0 (later estimated at around epsilon = 1/90). We present an algorithm that for every epsilon > 0 approximates the Densest k-Subgraph problem within a ratio of n(1/4+epsilon) in time n(O(1/epsilon)). If allowed to run for time n(O(log n)), the algorithm achieves an approximation ratio of O(n(1/4)). Our algorithm is inspired by studying an average-case version of the problem where the goal is to distinguish random graphs from random graphs with planted dense subgraphs - the approximation, ratio we achieve for the general case matches the \"distinguishing ratio\" we obtain for this planted Problem. At a high level, our algorithms involve cleverly counting appropriately defined trees of constant size in G, and using these counts to identify the vertices of the dense subgraph. We say that a graph G(V, E) has log-density alpha if its average degree is Theta(vertical bar V vertical bar(alpha))in The algorithmic core of our result is a procedure to output a k-subgraph of 'nontrivial' density whenever the log-density of the densest k-subgraph is larger than the log-density of the host graph. We outline an extension to our approximation algorithm which achieves an O(n(1/4-epsilon))-approximation in O(2(nO(epsilon))) time. We also show that, for certain parameter ranges, eigenvalue and SDP based techniques can outperform our basic distinguishing algorithm for random instances (in polynomial time), though without improving upon the O(n(1/4)) guarantee overall. We outline an extension to our approximation algorithm which achieves an O(n(1/4-epsilon))-approximation in O(2(nO(epsilon))) time. We also show that, for certain parameter ranges, eigenvalue and SDP based techniques can outperform our basic distinguishing algorithm for random instances (in polynomial time), though without improving upon the O(n(1/4)) guarantee overall.","Title: Modeling LSH for performance tuning\nYear: 2008\n\nAbstract: Although Locality-Sensitive Hashing (LSH) is a promising approach to similarity search in high-dimensional spaces, it has not been considered practical partly because its search quality is sensitive to several parameters that are quite data dependent. Previous research on LSH, though obtained interesting asymptotic results, provides little guidance on how these parameters should be chosen, and tuning parameters for a given dataset remains a tedious process. To address this problem, we present a statistical performance model of Multi-probe LSH, a state-of-the-art variance of LSH. Our model can accurately predict the average search quality and latency given a small sample dataset. Apart from automatic parameter tuning with the performance model, we also use the model to devise an adaptive LSH search algorithm to determine the probing parameter dynamically for each query. The adaptive probing method addresses the problem that even though the average performance is tuned for optimal, the variance of the performance is extremely high. We experimented with three different datasets including audio, images and 3D shapes to evaluate our methods. The results show the accuracy of the proposed model: the recall errors predicted are within 5% from the real values for most cases; the adaptive search method reduces the standard deviation of recall by about 50% over the existing method.","Title: On the advantage of network coding for improving network throughput\nYear: 2004\n\nAbstract: Given a data network with link capacities, we consider the throughput of the network for a multicast session involving a source node and a given set of terminals. It is known that network coding can improve the throughput of the network. We study the coding advantage, i.e. the ratio of the throughput using network coding to that without using network coding. We show that the maximum coding advantage for a given network is equal to the integrality gap of certain linear programming (LP) formulations for a Steiner tree. This holds for both directed as well as undirected networks. For directed networks, the coding advantage is equal to the integrality gap of the directed Steiner tree LP formulation; for undirected networks, the coding advantage is equal to the integrality gap of the bidirected cut LP formulation for the Steiner tree. This relates the coding advantage to well studied notions in combinatorial optimization. Further, this connection improves the known bounds on the coding advantage for both undirected as well directed networks.","Title: Clustering to minimize the sum of cluster diameters\nYear: 2004\n\nAbstract: We study the problem of clustering points in a metric space so as to minimize the sum of cluster diameters or the sum of cluster radii. Significantly improving on previous results, we present a primal-dual based constant factor approximation algorithm for this problem. We present a simple greedy algorithm that achieves a logarithmic approximation. This also applies when the distance function is asymmetric and the objective is to minimize the sum of cluster radii. The previous best-known result obtained a logarithmic approximation with a constant factor blowup in the number of clusters. We also obtain an incremental clustering algorithm that maintains a solution whose cost is at most a constant factor times that of optimal with a constant factor blowup in the number of clusters.","Title: Vertex Sparsifiers and Abstract Rounding Algorithms\nYear: 2010\n\nAbstract: The notion of vertex sparsification (in particular cut-sparsification) is introduced in (Moitra, 2009), where it was shown that for any graph $G = (V, E)$ and any subset of $k$ terminals $K \\subset V$, there is a polynomial time algorithm to construct a graph $H = (K, E_H)$ \\emph{on just the terminal set} so that simultaneously for all cuts $(A, K-A)$, the value of the minimum cut in $G$ separating $A$ from $K -A$ is approximately the same as the value of the corresponding cut in $H$. Then approximation algorithms can be run directly on $H$ as a proxy for running on $G$. We give the first super-constant lower bounds for how well a cut-sparsifier $H$ can simultaneously approximate all minimum cuts in $G$. %In fact, we prove that in general we cannot hope for approximation factors better than We prove a lower bound of $\\Omega(\\log^{1/4} k)$ – this is polynomially-related to the known upper bound of $O(\\log k/\\log \\log k)$. Independently, a similar lower bound is given in (Makarychev, Makarychev, 2010). This is an exponential improvement on the $\\Omega(\\log \\log k)$ bound given in (Leighton, Moitra, 2010) which in fact was for a stronger vertex sparsification guarantee, and did not apply to cut sparsifiers. Despite this negative result, we show that for many natural optimization problems, we do not need to incur a multiplicative penalty for our reduction. Roughly, we show that any rounding algorithm which also works for the $0$-extension relaxation can be used to construct good vertex-sparsifiers for which the optimization problem is easy. Using this, we obtain optimal $O(\\log k)$-competitive Steiner oblivious routing schemes, which generalize the results in (Raecke, 2008). We also demonstrate that for a wide range of graph packing problems (which includes maximum concurrent flow, maximum multiflow and multicast routing, among others, as a special case), the integrality gap of the linear program is always at most $O(\\log k)$ times the integrality gap restricted to trees. Lastly, we use our ideas to give an efficient construction for vertex-sparsifiers that match the current best existential results – this was previously open. Our algorithm makes novel use of Earth-mover constraints.","Title: Tight hardness results for minimizing discrepancy\nYear: 2011\n\nAbstract: In the Discrepancy problem, we are given M sets {S1,..., SM} on N elements. Our goal is to find an assignment χ of {−1, + 1} values to elements, so as to minimize the maximum discrepancy maxj | ΣiεSj χ(i)|. Recently, Bansal gave an efficient algorithm for achieving O(√N) discrepancy for any set system where M = O(N) [Ban10], giving a constructive version of Spencer's proof that the discrepancy of any set system is at most O(√N) for this range of M [Spe85]. We show that from the perspective of computational efficiency, these results are tight for general set systems where M = O(N). Specifically, we show that it is NP-hard to distinguish between such set systems with discrepancy zero and those with discrepancy Ω(√N). This means that even if the optimal solution has discrepancy zero, we cannot hope to efficiently find a coloring with discrepancy o(√N). We also consider the hardness of the Discrepancy problem on sets with bounded shatter function, and show that the upper bounds due to Matoušek [Mat95] are tight for these sets systems as well. The hardness results in both settings are obtained from a common framework: we compose a family of high discrepancy set systems with set systems for which it is NP-hard to distinguish instances with discrepancy zero from instances in which a large number of the sets (i.e. constant fraction of the sets) have non-zero discrepancy. Our composition amplifies this zero versus non-zero gap.","Title: On the impossibility of dimension reduction in l1\nYear: 2003\n\nAbstract: The Johnson--Lindenstrauss lemma shows that any n points in Euclidean space (i.e., ℝn with distances measured under the ℓ2 norm) may be mapped down to O((log n)/ε2) dimensions such that no pairwise distance is distorted by more than a (1 + ε) factor. Determining whether such dimension reduction is possible in ℓ1 has been an intriguing open question. We show strong lower bounds for general dimension reduction in ℓ1. We give an explicit family of n points in ℓ1 such that any embedding with constant distortion D requires nΩ(1/D2) dimensions. This proves that there is no analog of the Johnson--Lindenstrauss lemma for ℓ1; in fact, embedding with any constant distortion requires nΩ(1) dimensions. Further, embedding the points into ℓ1 with (1+ε) distortion requires n½−O(ε log(1/ε)) dimensions. Our proof establishes this lower bound for shortest path metrics of series-parallel graphs. We make extensive use of linear programming and duality in devising our bounds. We expect that the tools and techniques we develop will be useful for future investigations of embeddings into ℓ1.","Title: Smoothed analysis of tensor decompositions\nYear: 2013\n\nAbstract: Low rank decomposition of tensors is a powerful tool for learning generative models. The uniqueness results that hold for tensors give them a significant advantage over matrices. However, tensors pose serious algorithmic challenges; in particular, much of the matrix algebra toolkit fails to generalize to tensors. Efficient decomposition in the overcomplete case (where rank exceeds dimension) is particularly challenging. We introduce a smoothed analysis model for studying these questions and develop an efficient algorithm for tensor decomposition in the highly overcomplete case (rank polynomial in the dimension). In this setting, we show that our algorithm is robust to inverse polynomial error -- a crucial property for applications in learning since we are only allowed a polynomial number of samples. While algorithms are known for exact tensor decomposition in some overcomplete settings, our main contribution is in analyzing their stability in the framework of smoothed analysis. Our main technical contribution is to show that tensor products of perturbed vectors are linearly independent in a robust sense (i.e. the associated matrix has singular values that are at least an inverse polynomial). This key result paves the way for applying tensor methods to learning problems in the smoothed setting. In particular, we use it to obtain results for learning multi-view models and mixtures of axis-aligned Gaussians where there are many more \\\"components\\\" than dimensions. The assumption here is that the model is not adversarially chosen, which we formalize by thinking of the model parameters as being perturbed. We believe this an appealing way to analyze realistic instances of learning problems, since this framework allows us to overcome many of the usual limitations of using tensor methods.","Title: Sampling bounds for stochastic optimization\nYear: 2005\n\nAbstract: A large class of stochastic optimization problems can be modeled as minimizing an objective function f that depends on a choice of a vector x ∈ X, as well as on a random external parameter ω∈ Ω given by a probability distribution π. The value of the objective function is a random variable and often the goal is to find an x ∈ X to minimize the expected cost Eω[fω(x)]. Each ω is referred to as a scenario. We consider the case when Ω is large or infinite and we are allowed to sample from π in a black-box fashion. A common method, known as the SAA method (sample average approximation), is to pick sufficiently many independent samples from π and use them to approximate π and correspondingly Eω[fω(x)]. This is one of several scenario reduction methods used in practice. There has been substantial recent interest in two-stage stochastic versions of combinatorial optimization problems which can be modeled by the framework described above. In particular, we are interested in the model where a parameter λ bounds the relative factor by which costs increase if decisions are delayed to the second stage. Although the SAA method has been widely analyzed, the known bounds on the number of samples required for a (1+ε) approximation depend on the variance of π even when λ is assumed to be a fixed constant. Shmoys and Swamy [13,14] proved that a polynomial number of samples suffice when f can be modeled as a linear or convex program. They used modifications to the ellipsoid method to prove this. In this paper we give a different proof, based on earlier methods of Kleywegt, Shapiro, Homem-De-Mello [6] and others, that a polynomial number of samples suffice for the SAA method. Our proof is not based on computational properties of f and hence also applies to integer programs. We further show that small variations of the SAA method suffice to obtain a bound on the sample size even when we have only an approximation algorithm to solve the sampled problem. We are thus able to extend a number of algorithms designed for the case when π is given explicitly to the case when π is given as a black-box sampling oracle.","Title: Efficient filtering with sketches in the ferret toolkit\nYear: 2006\n\nAbstract: Ferret is a toolkit for building content-based similarity search systems for feature-rich data types such as audio, video, and digital photos.The key component of this toolkit is a content-based similarity search engine for generic, multi-feature object representations. This paper describes the filtering mechanism used in the Ferret toolkit and experimental results with several datasets. The filtering mechanism uses approximation algorithms to generate a candidate set, and then ranks the objects in the candidate set with a more sophisticated multi-feature distance measure. The paper compared two filtering methods: using segment feature vectors and sketches constructed from segment feature vectors. Our experimental results show that filtering can substantially speedup the search process and reduce memory requirement while maintaining good search quality. To help systems designers choose the filtering parameters, we have developed a rank-based analytical model for the filtering algorithm using sketches. Our experiments show that the model gives conservative and good prediction for different datasets.","Title: Approximating min-sum k-clustering in metric spaces\nYear: 2001\n\nAbstract: The min-sum k-clustering problem in a metric space is to find a partition of the space into k clusters as to minimize the total sum of distances between pairs of points assigned to the same cluster. We give the first polynomial time non-trivial approximation algorithm for this problem. The algorithm provides an $\\ratio$ approximation to the min-sum k-clustering problem in general metric spaces, with running time $\\runtime$. The result is based on embedding of metric spaces into hierarchically separated trees. We also provide a bicriteria approximation result that provides a constant approximation factor solution with only a constant factor increase in the number of clusters. This result is obtained by modifying and drawing ideas from recently developed primal dual approximation algorithms for facility location.","Title: On the Integrality Ratio for the Asymmetric Traveling Salesman Problem\nYear: 2006\n\nAbstract: We improve the lower bound on the integrality ratio of the Held-Karp bound for asymmetric TSP with triangle inequality from 4/3 to 2.","Title: Directed metrics and directed graph partitioning problems\nYear: 2006\n\nAbstract: The theory of embeddings of finite metrics has provided a powerful toolkit for graph partitioning problems in undirected graphs. The connection comes from the fact that the integrality gaps of mathematical programming relaxations for sparsest cut in undirected graphs is exactly equal to the minimum distortion required to embed certain metrics into l1. No analog of this metric embedding theory exists for directed (asymmetric) metrics, the natural distance functions that arise in considering mathematical relaxations for directed graph partioning problems. We initiate a study of metric embeddings for directed metrics, motivated by understanding directed variants of sparsest cut.It turns out that there are two different ways to formulate sparsest cut in directed graphs (depending on whether one insists on partitioning the graph into two pieces or not). Different subclasses of directed metrics arise in the consideration of mathematical relaxations for these two formulations and the embedding questions that result are quite different. Unlike in the undirected case, where the natural host space is l1, the host space in the directed case is not obvious and depends on the problem formulation. Our work is a first step at understanding this space of directed metrics, the resulting embedding questions and their relationships to directed graph partitioning problems.","Title: Beating the Random Ordering Is Hard: Every Ordering CSP Is Approximation Resistant\nYear: 2011\n\nAbstract: We prove that, assuming the Unique Games conjecture (UGC), every problem in the class of ordering constraint satisfaction problems (OCSPs) where each constraint has constant arity is approximation resistant. In other words, we show that if $\\rho$ is the expected fraction of constraints satisfied by a random ordering, then obtaining a $\\rho'$ approximation for any $\\rho'\\rho$ is UG-hard. For the simplest OCSP, the Maximum Acyclic Subgraph (MAS) problem, this implies that obtaining a $\\rho$-approximation for any constant $\\rho1/2$ is UG-hard. Specifically, for every constant $\\varepsilon0$ the following holds: given a directed graph $G$ that has an acyclic subgraph consisting of a fraction $(1-\\varepsilon)$ of its edges, it is UG-hard to find one with more than $(1/2+\\varepsilon)$ of its edges. Note that it is trivial to find an acyclic subgraph with $1/2$ the edges by taking either the forward or backward edges in an arbitrary ordering of the vertices of $G$. The MAS problem has been well studied, and beating the random ordering for MAS has been a basic open problem. An OCSP of arity $k$ is specified by a subset $\\Pi\\subseteq S_k$ of permutations on $\\{1,2,\\dots,k\\}$. An instance of such an OCSP is a set $V$ and a collection of constraints, each of which is an ordered $k$-tuple of $V$. The objective is to find a global linear ordering of $V$ while maximizing the number of constraints ordered as in $\\Pi$. A random ordering of $V$ is expected to satisfy a $\\rho=\\frac{|\\Pi|}{k!}$ fraction. We show that, for any fixed $k$, it is hard to obtain a $\\rho'$-approximation for $\\Pi$-OCSP for any $\\rho'\\rho$. The result is in fact stronger: we show that for every $\\Lambda\\subseteq\\Pi\\subseteq S_k$, and an arbitrarily small $\\varepsilon$, it is hard to distinguish instances where a $(1-\\varepsilon)$ fraction of the constraints can be ordered according to $\\Lambda$ from instances where at most a $(\\rho+\\varepsilon)$ fraction can be ordered as in $\\Pi$. A special case of our result is that the Betweenness problem is hard to approximate beyond a factor $1/3$. The results naturally generalize to OCSPs which assign a payoff to the different permutations. Finally, our results imply (unconditionally) that a simple semidefinite relaxation for MAS does not suffice to obtain a better approximation.","Title: Delayed information and action in on-line algorithms\nYear: 1998\n\nAbstract: Most on-line analysis assumes that, at each time step, all relevant information up to that time step is available and a decision has an immediate effect. In many on-line problems, however, the time when relevant information is available and the time a decision has an effect may be decoupled. For example, when making an investment, one might not have completely up-to-date information on market prices. Similarly, a buy or sell order might only be executed some time in the future. We introduce and explore natural delayed models for several well-known on-line problems. Our analyses demonstrate the importance of considering timeliness in determining the competitive ratio of an on-line algorithm. For many problems, we demonstrate that there exist algorithms with small competitive ratios even when large delays affect the timeliness of information and the effect of decisions. Copyright 2001 Academic Press.","Title: The Finite Capacity Dial-A-Ride Problem\nYear: 1998\n\nAbstract: We give the first non-trivial approximation algorithm for the Capacitated Dial-a-Ride problem: given a collection of objects located at points in a metric space, a specified destination point for each object, and a vehicle with a capacity of at most k objects, the goal is to compute a shortest tour for the vehicle in which all objects can be delivered to their destinations while ensuring that the vehicle carries at most k objects at any point in time. The problem is known under several names, including the Stacker Crane problem and the Dial-a-Ride problem. No theoretical approximation guarantees were known for this problem other than for the cases k=1,\\infty and the trivial O(k) approximation for general capacity k. We give an algorithm with approximation ratio O(sqrt{k}) for special instances on a class of tree metrics called height-balanced trees. Using Bartal's recent results on the probabilistic approximation of metric spaces by tree metrics, we obtain an approximation ratio of O(sqrt{k} log n log log n)$ for arbitrary n point metric spaces. When the points lie on a line (line metric), we provide a 2-approximation algorithm.We also consider the Dial-a-Ride problem in another framework: when the vehicle is allowed to leave objects at intermediate locations and pick them up at a later time and deliver them. For this model, we design an approximation algorithm whose performance ratio is O(1) for tree metrics and O(log n log log n) for arbitrary metrics.We also study the ratio between the values of the optimal solutions for the two versions of the problem. We show that unlike in k-delivery TSP in which all the objects are identical, this ratio is not bounded by a constant for the Dial-a-Ride problem, and it could be as large as \\Omega(k^{2/3}).","Title: Fitting Tree Metrics: Hierarchical Clustering and Phylogeny\nYear: 2011\n\nAbstract: Given dissimilarity data on pairs of objects in a set, we study the problem of fitting a tree metric to this data so as to minimize additive error (i.e. some measure of the difference between the tree metric and the given data). This problem arises in constructing an M -level hierarchical clustering of objects (or an ultrametric on objects) so as to match the given dissimilarity data - a basic problem in statistics. Viewed in this way, the problem is a generalization of the correlation clustering problem (which corresponds to M = 1). We give a very simple randomized combinatorial algorithm for the M - level hierarchical clustering problem that achieves an approximation ratio of M +2. This is a generalization of a previous factor 3 algorithm for correlation clustering on complete graphs. The problem of fitting tree metrics also arises in phylogeny where the objective is to learn the evolution tree by fitting a tree to dissimilarity data on taxa. The quality of the fit is measured by taking the 'p norm of the difference between the tree metric con- structed and the given data. Previous results obtained a factor 3 approximation for finding the closest tree tree metric under the '1 norm. No non-trivial approxima- tion for general 'p norms was known before. We present a novel LP formulation for this problem and obtain an O((log n log log n) 1=p ) approximation using this. En route, we obtain an O((log n log log n) 1=p ) approxima- tion for the closest ultrametric under the 'p norm. Our techniques are based on representing and viewing an ul- trametric as a hierarchy of clusterings, and may be use- ful in other contexts.","Title: Every Permutation CSP of arity 3 is Approximation Resistant\nYear: 2009\n\nAbstract: A permutation constraint satisfaction problem (permCSP) of arity k is specified by a subset Lambda of permutations on $\\{1,2,\\dots,k\\}$. An instance of such a permCSP consists of a set of variables $V$ and a collection of constraints each of which is an ordered $k$-tuple of $V$. The objective is to find a global ordering $\\sigma$ of the variables that maximizes the number of constraint tuples whose ordering (under $\\sigma$) follows a permutation in $\\Lambda$. This is just the natural extension of constraint satisfaction problems over finite domains (such as Boolean CSPs) to the world of ordering problems. The simplest permCSP corresponds to the case when $\\Lambda$ consists of the identity permutation on two variables. This is just the Maximum Acyclic Subgraph (\\mas) problem. It was recently shown that the \\mas\\ problem is Unique-Games hard to approximate within a factor better than the trivial $1/2$ achieved by a random ordering [GMR08]. Building on this work, in this paper we show that for *every* permCSP of arity $3$, beating the random ordering is Unique-Games hard. The result is in fact stronger: we show that for every $\\Lambda \\subseteq \\Pi \\subseteq S_3$, given an instance of permCSP$(\\Lambda)$ that is almost-satisfiable, it is hard to find an ordering that satisfies more than $\\frac{|\\Pi|}{6} +\\eps$ of the constraints even under the relaxed constraint $\\Pi$ (for arbitrary $\\eps 0$). A special case of our result is that the *Betweenness* problem is hard to approximate beyond a factor $1/3$. Interestingly, for *satisfiable* instances of Betweenness, a factor $1/2$ approximation algorithm is known. Thus, every permutation CSP of arity up to $3$ resists approximation beyond the trivial random ordering threshold. In contrast, for Boolean CSPs, there are both approximation resistant and non-trivially approximable CSPs of arity $3$.","Title: Limits of Approximation Algorithms: PCPs and Unique Games (DIMACS Tutorial Lecture Notes)\nYear: 2010\n\nAbstract: These are the lecture notes for the DIMACS Tutorial \"Limits of Approximation\nAlgorithms: PCPs and Unique Games\" held at the DIMACS Center, CoRE Building,\nRutgers University on 20-21 July, 2009. This tutorial was jointly sponsored by\nthe DIMACS Special Focus on Hardness of Approximation, the DIMACS Special Focus\non Algorithmic Foundations of the Internet, and the Center for Computational\nIntractability with support from the National Security Agency and the National\nScience Foundation.\n The speakers at the tutorial were Matthew Andrews, Sanjeev Arora, Moses\nCharikar, Prahladh Harsha, Subhash Khot, Dana Moshkovitz and Lisa Zhang. The\nsribes were Ashkan Aazami, Dev Desai, Igor Gorodezky, Geetha Jagannathan,\nAlexander S. Kulikov, Darakhshan J. Mir, Alantha Newman, Aleksandar Nikolov,\nDavid Pritchard and Gwen Spencer.","Title: Greedy approximation algorithms for finding dense components in a graph\nYear: 2000\n\nAbstract: We study the problem of finding highly connected subgraphs of undirected and directed graphs. For undirected graphs, the notion of density of a subgraph we use is the average degree of the subgraph. For directed graphs, a corresponding notion of density was introduced recently by Kannan and Vinay. This is designed to quantify highly connectedness of substructures in a sparse directed graph such as the web graph. We study the optimization problems of finding subgraphs maximizing these notions of density for undirected and directed graphs. This paper gives simple greedy approximation algorithms for these optimization problems. We also answer an open question about the complexity of the optimization problem for directed graphs.","Title: Approximating the smallest grammar: Kolmogorov complexity in natural models\nYear: 2002\n\nAbstract: We consider the problem of finding the smallest context-free grammar that generates exactly one given string of length n. The size of this grammar is of theoretical interest as an efficiently computable variant of Kolmogorov complexity. The problem is of practical importance in areas such as data compression and pattern extraction.The smallest grammar is known to be hard to approximate to within a constant factor, and an o(logn/log logn) approximation would require progress on a long-standing algebraic problem [10]. Previously, the best proved approximation ratio was O(n1/2) for the Bisection algorithm [8]. Our main result is an exponential improvement of this ratio; we give an O(log (n/g*)) approximation algorithm, where g* is the size of the smallest grammar.We then consider other computable variants of Kolomogorov complexity. In particular we give an O(log2 n) approximation for the smallest non-deterministic finite automaton with advice that produces a given string. We also apply our techniques to \"advice-grammars\" and \"edit-grammars\", two other natural models of string complexity.","Title: Integrality gaps for Sherali-Adams relaxations\nYear: 2009\n\nAbstract: We prove strong lower bounds on integrality gaps of Sherali-Adams relaxations for MAX CUT, Vertex Cover, Sparsest Cut and other problems. Our constructions show gaps for Sherali-Adams relaxations that survive nδ rounds of lift and project. For MAX CUT and Vertex Cover, these show that even nδ rounds of Sherali-Adams do not yield a better than 2-ε approximation. The main combinatorial challenge in constructing these gap examples is the construction of a fractional solution that is far from an integer solution, but yet admits consistent distributions of local solutions for all small subsets of variables. Satisfying this consistency requirement is one of the major hurdles to constructing Sherali-Adams gap examples. We present a modular recipe for achieving this, building on previous work on metrics with a local-global structure. We develop a conceptually simple geometric approach to constructing Sherali-Adams gap examples via constructions of consistent local SDP solutions. This geometric approach is surprisingly versatile. We construct Sherali-Adams gap examples for Unique Games based on our construction for MAX CUT together with a parallel repetition like procedure. This in turn allows us to obtain Sherali-Adams gap examples for any problem that has a Unique Games based hardness result (with some additional conditions on the reduction from Unique Games). Using this, we construct 2-ε gap examples for Maximum Acyclic Subgraph that rules out any family of linear constraints with support at most nδ.","Title: Approximating a Finite Metric by a Small Number of Tree Metrics\nYear: 1998\n\nAbstract: Bartal gave a randomized polynomial time algorithm that given any n point metric G, constructs a tree T such that the expected stretch (distortion) of any edge is at most O(log n log log n). His result has found several applications and in particular has resulted in approximation algorithms for many graph optimization problems. However approximation algorithms based on his result are inherently randomized. In this paper we derandomize the use of Bartal's algorithm in the design of approximation algorithms.We give an efficient polynomial time algorithm that given a finite n point metric G, constructs O(n log n) trees and a probability distribution \\mu on them such that the expected stretch of any edge of G in a tree chosen according to \\mu is at most O(log n log log n). Our result establishes that finite metrics can be probabilistically approximated by a small number of tree metrics. We obtain the first deterministic approximation algorithms for buy-at-bulk network design and vehicle routing; in addition we subsume results from our earlier work on derandomization. Our main result is obtained by a novel view of probabilistic approximation of metric spaces as a deterministic optimization problem via linear programming. This view also provides a new proof of Bartal's result that might be easier to generalize.We also show that graphs induced by points in \\Re^d_p (d-dimensional real normed space equipped with the l_p norm) can be O(f(d,p) log n)- -probabilistically approximated by tree metrics where f(d,p) = d^{1/p} for 1","Title: Relax, No Need to Round: Integrality of Clustering Formulations\nYear: 2014\n\nAbstract: We study exact recovery conditions for convex relaxations of point cloud clustering problems, focusing on two of the most common optimization problems for unsupervised clustering: k-means and k-median clustering. Motivations for focusing on convex relaxations are: (a) they come with a certificate of optimality, and (b) they are generic tools which are relatively parameter-free, not tailored to specific assumptions over the input. More precisely, we consider the distributional setting where there are k clusters in Rm and data from each cluster consists of n points sampled from a symmetric distribution within a ball of unit radius. We ask: what is the minimal separation distance between cluster centers needed for convex relaxations to exactly recover these k clusters as the optimal integral solution? For the k-median linear programming relaxation we show a tight bound: exact recovery is obtained given arbitrarily small pairwise separation ε > O between the balls. In other words, the pairwise center separation is δ > 2+ε. Under the same distributional model, the k-means LP relaxation fails to recover such clusters at separation as large as δ = 4. Yet, if we enforce PSD constraints on the k-means LP, we get exact cluster recovery at separation as low as δ > min{2 + √2k/m}, 2+√2 + 2/m} + ε. In contrast, common heuristics such as Lloyd's algorithm (a.k.a. the k means algorithm) can fail to recover clusters in this setting; even with arbitrarily large cluster separation, k-means++ with overseeding by any constant factor fails with high probability at exact cluster recovery. To complement the theoretical analysis, we provide an experimental study of the recovery guarantees for these various methods, and discuss several open problems which these experiments suggest.","Title: Online Bipartite Matching with Decomposable Weights.\nYear: 2014\n\nAbstract: We study a weighted online bipartite matching problem: G(V-1, V-2, E) is a weighted bipartite graph where V-1 is known beforehand and the vertices of V-2 arrive online. The goal is to match vertices of V-2 as they arrive to vertices in V-1, so as to maximize the sum of weights of edges in the matching. If assignments to V-1 cannot be changed, no bounded competitive ratio is achievable. We study the weighted online matching problem with free disposal, where vertices in V-1 can be assigned multiple times, but only get credit for the maximum weight edge assigned to them over the course of the algorithm. For this problem, the greedy algorithm is 0.5-competitive and determining whether a better competitive ratio is achievable is a well known open problem. We identify an interesting special case where the edge weights are decomposable as the product of two factors, one corresponding to each end point of the edge. This is analogous to the well studied related machines model in the scheduling literature, although the objective functions are different. For this case of decomposable edge weights, we design a 0.5664 competitive randomized algorithm in complete bipartite graphs. We show that such instances with decomposable weights are non-trivial by establishing upper bounds of 0.618 for deterministic and 0.8 for randomized algorithms. A tight competitive ratio of 1 - 1/e approximate to 0.632 was known previously for both the 0-1 case as well as the case where edge weights depend on the offline vertices only, but for these cases, reassignments cannot change the quality of the solution. Beating 0.5 for weighted matching where reassignments are necessary has been a significant challenge. We thus give the first online algorithm with competitive ratio strictly better than 0.5 for a non-trivial case of weighted matching with free disposal.","Title: Resource optimization in QoS multicast routing of real-time multimedia\nYear: 2004\n\nAbstract: We consider a network design problem, where applications require various levels of Quality-of-Service (QoS) while connections have limited performance. Suppose that a source needs to send a message to a heterogeneous set of receivers. The objective is to design a low-cost multicast tree from the source that would provide the QoS levels (e.g., bandwidth) requested by the receivers. We assume that the QoS level required on a link is the maximum among the QoS levels of the receivers that are connected to the source through the link. In accordance, we define the cost of a link to be a function of the QoS level that it provides. This definition of cost makes this optimization problem more general than the classical Steiner tree problem. We consider several variants of this problem all of which are proved to be NP-Hard. For the variant where QoS levels of a link can vary arbitrarily and the cost function is linear in its QoS level, we give a heuristic that achieves a multicast tree with cost at most a constant times the cost of an optimal multicast tree. The constant depends on the best constant approximation ratio of the classical Steiner tree problem. For the more general variant, where each link has a given QoS level and cost we present a heuristic that generates a multicast tree with cost O(min {log r, k}) times the cost of an optimal tree, where r denotes the number of receivers, and k denotes the number of different levels of QoS required. We generalize this result to hold for the case of many multicast groups.","Title: Maximizing quadratic programs: extending Grothendieck's inequality\nYear: 2004\n\nAbstract: This paper considers the following type of quadratic programming problem. Given an arbitrary matrix A, whose diagonal elements are zero, find x 驴 {-1, 1}^n such that x^TAx is maximized. Our approximation algorithm for this problem uses the canonical semidefinite relaxation and returns a solution whose ratio to the optimum is in 驴(1/log n). This quadratic programming problem can be seen as an extension to that of maximizing x^TAy (where y's components are also 卤1). Grothendieck's inequality states that the ratio of the optimum value of the latter problem to the optimum of its canonical semidefinite relaxation is bounded below by a constant. The study of this type of quadratic program arose from a desire to approximate the maximum correlation in correlation clustering. Nothing substantive was known about this problem; we present an 驴(1/log n) approximation, based on our quadratic programming algorithm. We can also guarantee that our quadratic programming algorithm returns a solution to the MAXCUT problem that has a significant advantage over a random assignment.","Title: Minimum outage transmission over fading channels with delay constraint\nYear: 2000\n\nAbstract: We consider a block flat fading channel, where both the transmitter and receiver have perfect knowledge of the channel gain of the current block, but have no knowledge of future blocks. For a delay constraint of K blocks, and a target rate R0, we derive the optimum power adaptation strategy that would minimize the probability of outage, which is equivalent to finding the outage capacity. Both, short term and long term power constraints are considered. Significant power gains are afforded by the strategy for all SNRs, even for small K","Title: The Hardness of Approximation of Euclidean k-means.\nYear: 2015\n\nAbstract: The Euclidean $k$-means problem is a classical problem that has been extensively studied in the theoretical computer science, machine learning and the computational geometry communities. In this problem, we are given a set of $n$ points in Euclidean space $R^d$, and the goal is to choose $k$ centers in $R^d$ so that the sum of squared distances of each point to its nearest center is minimized. The best approximation algorithms for this problem include a polynomial time constant factor approximation for general $k$ and a $(1+\\epsilon)$-approximation which runs in time $poly(n) 2^{O(k/\\epsilon)}$. At the other extreme, the only known computational complexity result for this problem is NP-hardness [ADHP'09]. The main difficulty in obtaining hardness results stems from the Euclidean nature of the problem, and the fact that any point in $R^d$ can be a potential center. This gap in understanding left open the intriguing possibility that the problem might admit a PTAS for all $k,d$. In this paper we provide the first hardness of approximation for the Euclidean $k$-means problem. Concretely, we show that there exists a constant $\\epsilon > 0$ such that it is NP-hard to approximate the $k$-means objective to within a factor of $(1+\\epsilon)$. We show this via an efficient reduction from the vertex cover problem on triangle-free graphs: given a triangle-free graph, the goal is to choose the fewest number of vertices which are incident on all the edges. Additionally, we give a proof that the current best hardness results for vertex cover can be carried over to triangle-free graphs. To show this we transform $G$, a known hard vertex cover instance, by taking a graph product with a suitably chosen graph $H$, and showing that the size of the (normalized) maximum independent set is almost exactly preserved in the product graph using a spectral analysis, which might be of independent interest.","Title: Label optimal regret bounds for online local learning.\nYear: 2015\n\nAbstract: We resolve an open question from (Christiano, 2014b) posed in COLT'14 regarding the optimal dependency of the regret achievable for online local learning on the size of the label set. In this framework the algorithm is shown a pair of items at each step, chosen from a set of $n$ items. The learner then predicts a label for each item, from a label set of size $L$ and receives a real valued payoff. This is a natural framework which captures many interesting scenarios such as collaborative filtering, online gambling, and online max cut among others. (Christiano, 2014a) designed an efficient online learning algorithm for this problem achieving a regret of $O(\\sqrt{nL^3T})$, where $T$ is the number of rounds. Information theoretically, one can achieve a regret of $O(\\sqrt{n \\log L T})$. One of the main open questions left in this framework concerns closing the above gap. In this work, we provide a complete answer to the question above via two main results. We show, via a tighter analysis, that the semi-definite programming based algorithm of (Christiano, 2014a), in fact achieves a regret of $O(\\sqrt{nLT})$. Second, we show a matching computational lower bound. Namely, we show that a polynomial time algorithm for online local learning with lower regret would imply a polynomial time algorithm for the planted clique problem which is widely believed to be hard. We prove a similar hardness result under a related conjecture concerning planted dense subgraphs that we put forth. Unlike planted clique, the planted dense subgraph problem does not have any known quasi-polynomial time algorithms. Computational lower bounds for online learning are relatively rare, and we hope that the ideas developed in this work will lead to lower bounds for other online learning scenarios as well.","Title: Spectral Embedding Of K-Cliques, Graph Partitioning And K-Means\nYear: 2016\n\nAbstract: We introduce and study a new notion of graph partitioning, intimately connected to spectral clustering and k-means clustering. Formally, given a graph G on n vertices, we ask to find a graph H that is the union of k cliques on n vertices, such that LG >=lambda L-H where ? is maximized. Here L-G and L-H are the (normalized) Laplacians of the graphs G and H respectively. Informally, our graph partitioning objective asks for the optimal spectral simplification of a given graph as a disjoint union of k cliques.We justify this objective function in several ways. First and foremost, we show that a commonly used spectral clustering algorithm implicitly optimizes this objective function, up to a factor of O(k). Using this connection, we immediately get an O(k)-approximation algorithm to our new objective function by simply using the spectral clustering algorithm on G. Next, we demonstrate another application of our objective function: we use it as a means to proving that simple spectral clustering algorithms can solve some well-studied graph partitioning problems (such as partitioning into expanders). Additionally, we also show that (a relaxation of) this optimization problem naturally arises as the dual problem to the question of finding the worst-case integrality gap instance for the classical k-means SDP. Finally, owing to these close connection between some classical clustering techniques (such as k-means and spectral clustering), we argue that a more complete understanding of this optimization problem could lead to new algorithmic insights and techniques for the area of graph partitioning.","Title: On Approximating Target Set Selection.\nYear: 2016\n\nAbstract: We study the Target Set Selection (TSS) problem introduced by Kempe, Kleinberg, and Tardos (2003). This problem models the propagation of influence in a network, in a sequence of rounds. A set of nodes is made active initially. In each subsequent round, a vertex is activated if at least a certain number of its neighbors are (already) active. In the minimization version, the goal is to activate a small set of vertices initially - a seed, or target, set - so that activation spreads to the entire graph. In the absence of a sublinear-factor algorithm for the general version, we provide a (sublinear) approximation algorithm for the bounded-round version, where the goal is to activate all the vertices in r rounds. Assuming a known conjecture on the hardness of Planted Dense Subgraph, we establish hardness-of-approximation results for the bounded-round version. We show that they translate to general Target Set Selection, leading to a hardness factor of n^(1/2-epsilon) for all epsilon u003e 0. This is the first polynomial hardness result for Target Set Selection, and the strongest conditional result known for a large class of monotone satisfiability problems. In the maximization version of TSS, the goal is to pick a target set of size k so as to maximize the number of nodes eventually active. We show an n^(1-epsilon) hardness result for the undirected maximization version of the problem, thus establishing that the undirected case is as hard as the directed case. Finally, we demonstrate an SETH lower bound for the exact computation of the optimal seed set.","Title: Learning from Untrusted Data.\nYear: 2017\n\nAbstract: The vast majority of theoretical results in machine learning and statistics assume that the training data is a reliable reflection of the phenomena to be learned. Similarly, most learning techniques used in practice are brittle to the presence of large amounts of biased or malicious data. Motivated by this, we consider two frameworks for studying estimation, learning, and optimization in the presence of significant fractions of arbitrary data. The first framework, list-decodable learning, asks whether it is possible to return a list of answers such that at least one is accurate. For example, given a dataset of n points for which an unknown subset of α n points are drawn from a distribution of interest, and no assumptions are made about the remaining (1âα)n points, is it possible to return a list of poly(1/α) answers? The second framework, which we term the semi-verified model, asks whether a small dataset of trusted data (drawn from the distribution in question) can be used to extract accurate information from a much larger but untrusted dataset (of which only an α-fraction is drawn from the distribution). We show strong positive results in both settings, and provide an algorithm for robust learning in a very general stochastic optimization setting. This result has immediate implications for robustly estimating the mean of distributions with bounded second moments, robustly learning mixtures of such distributions, and robustly finding planted partitions in random graphs in which significant portions of the graph have been perturbed by an adversary.","Title: Approximate Hierarchical Clustering via Sparsest Cut and Spreading Metrics.\nYear: 2016\n\nAbstract: Dasgupta recently introduced a cost function for the hierarchical clustering of a set of points given pairwise similarities between them. He showed that this function is NP-hard to optimize, but a top-down recursive partitioning heuristic based on an αn-approximation algorithm for uniform sparsest cut gives an approximation of O(αn log n) (the current best algorithm has [EQUATION]. We show that the aforementioned sparsest cut heuristic in fact obtains an O(αn)-approximation. The algorithm also applies to a generalized cost function studied by Dasgupta. Moreover, we obtain a strong inapproximability result, showing that the Hierarchical Clustering objective is hard to approximate to within any constant factor assuming the Small-Set Expansion (SSE) Hypothesis. Finally, we discuss approximation algorithms based on convex relaxations. We present a spreading metric SDP relaxation for the problem and show that it has integrality gap at most [EQUATION]. The advantage of the SDP relative to the sparsest cut heuristic is that it provides an explicit lower bound on the optimal solution and could potentially yield an even better approximation for hierarchical clustering. In fact our analysis of this SDP served as the inspiration for our improved analysis of the sparsest cut heuristic. We also show that a spreading metric LP relaxation gives an O(log n)-approximation.","Title: Local Guarantees In Graph Cuts And Clustering\nYear: 2017\n\nAbstract: Correlation Clustering is an elegant model that captures fundamental graph cut problems such as Min s - t Cut, Multiway Cut, and Multicut, extensively studied in combinatorial optimization. Here, we are given a graph with edges labeled + or - and the goal is to produce a clustering that agrees with the labels as much as possible: + edges within clusters and - edges across clusters. The classical approach towards Correlation Clustering (and other graph cut problems) is to optimize a global objective. We depart from this and study local objectives: minimizing the maximum number of disagreements for edges incident on a single node, and the analogous max min agreements objective. This naturally gives rise to a family of basic min-max graph cut problems. A prototypical representative is Min Max s-t Cut: find an s-t cut minimizing the largest number of cut edges incident on any node. We present the following results: (1) an O(root n)-approximation for the problem of minimizing the maximum total weight of disagreement edges incident on any node (thus providing the first known approximation for the above family of min-max graph cut problems), (2) a remarkably simple 7-approximation for minimizing local disagreements in complete graphs (improving upon the previous best known approximation of 48), and (3) a 1/(2+epsilon)-approximation for maximizing the minimum total weight of agreement edges incident on any node, hence improving upon the 1/(4+epsilon)-approximation that follows from the study of approximate pure Nash equilibria in cut and party affiliation games.","Title: Resilience: A Criterion for Learning in the Presence of Arbitrary Outliers.\nYear: 2018\n\nAbstract: We introduce a criterion, resilience, which allows properties of a dataset (such as its mean or best low rank approximation) to be robustly computed, even in the presence of a large fraction of arbitrary additional data. Resilience is a weaker condition than most other properties considered so far in the literature, and yet enables robust estimation in a broader variety of settings. We provide new information-theoretic results on robust distribution learning, robust estimation of stochastic block models, and robust mean estimation under bounded kth moments. We also provide new algorithmic results on robust distribution learning, as well as robust mean estimation in p-norms. Among our proof techniques is a method for pruning a high-dimensional distribution with bounded 1st moments to a stable core with bounded 2nd moments, which may be of independent interest.","Title: Intelligent probing for locality sensitive hashing: multi-probe LSH and beyond\nYear: 2017\n\nAbstract: AbstractThe past decade has been marked by the (continued) explosion of diverse data content and the fast development of intelligent data analytics techniques. One problem we identified in the mid-2000s was similarity search of feature-rich data. The challenge here was achieving both high accuracy and high efficiency in high-dimensional spaces. Locality sensitive hashing (LSH), which uses certain random space partitions and hash table lookups to find approximate nearest neighbors, was a promising approach with theoretical guarantees. But LSH alone was insufficient since a large number of hash tables were required to achieve good search quality. Building on an idea of Panigrahy, our multi-probe LSH method introduced the idea of intelligent probing. Given a query object, we strategically probe its neighboring hash buckets (in a query-dependent fashion) by calculating the statistical probabilities of similar objects falling into each bucket. Such intelligent probing can significantly reduce the number of hash tables while achieving high quality. In this paper, we revisit the problem motivation, the challenges, the key design considerations of multi-probe LSH, as well as discuss recent developments in this space and some questions for further research.","Title: Min-Cost Bipartite Perfect Matching with Delays.\nYear: 2017\n\nAbstract: In the min-cost bipartite perfect matching with delays (MBPMD) problem, requests arrive online at points of a finite metric space. Each request is either positive or negative and has to be matched to a request of opposite polarity. As opposed to traditional online matching problems, the algorithm does not have to serve requests as they arrive, and may choose to match them later at a cost. Our objective is to minimize the sum of the distances between matched pairs of requests (the connection cost) and the sum of the waiting times of the requests (the delay cost). This objective exhibits a natural tradeoff between minimizing the distances and the cost of waiting for better matches. This tradeoff appears in many real-life scenarios, notably, ride-sharing platforms. MBPMD is related to its non-bipartite variant, min-cost perfect matching with delays (MPMD), in which each request can be matched to any other request. MPMD was introduced by Emek et al. (STOCu002716), who showed an O(log^2(n)+log(Delta))-competitive randomized algorithm on n-point metric spaces with aspect ratio Delta.Our contribution is threefold. First, we present a new lower bound construction for MPMD and MBPMD. We get a lower bound of Omega(sqrt(log(n)/log(log(n)))) on the competitive ratio of any randomized algorithm for MBPMD. For MPMD, we improve the lower bound from Omega(sqrt(log(n))) (shown by Azar et al., SODAu002717) to Omega(log(n)/log(log(n))), thus, almost matching their upper bound of O(log(n)). Second, we adapt the algorithm of Emek et al. to the bipartite case, and provide a simplified analysis that improves the competitive ratio to O(log(n)). The key ingredient of the algorithm is an O(h)-competitive randomized algorithm for MBPMD on weighted trees of height h. Third, we provide an O(h)-competitive deterministic algorithm for MBPMD on weighted trees of height h. This algorithm is obtained by adapting the algorithm for MPMD by Azar et al. to the apparently more complicated bipartite setting.","Title: Hashing-Based-Estimators for Kernel Density in High Dimensions\nYear: 2018\n\nAbstract: Given a set of points P ⊂ ℝ\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">d</sup>\n and a kernel k, the Kernel Density Estimate at a point x ∈ ℝ\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">d</sup>\n is defined as KDE\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">P</sub>\n (x) = 1/|P| Σy\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">∈P</sub>\n k(x, y). We study the problem of designing a data structure that given a data set P and a kernel function, returns approximations to the kernel density of a query point in sublinear time. We introduce a class of unbiased estimators for kernel density implemented through locality-sensitive hashing, and give general theorems bounding the variance of such estimators. These estimators give rise to efficient data structures for estimating the kernel density in high dimensions for a variety of commonly used kernels. Our work is the first to provide data-structures with theoretical guarantees that improve upon simple random sampling in high dimensions.","Title: Fully Dynamic Almost-Maximal Matching: Breaking the Polynomial Barrier for Worst-Case Time Bounds.\nYear: 2017\n\nAbstract: Despite significant research efforts, the state-of-the-art algorithm for maintaining an approximate matching in fully dynamic graphs has a polynomial emph{worst-case} update time, even for very poor approximation guarantees. a recent breakthrough, Bhattacharya, Henzinger and Nanongkai showed how to maintain a constant approximation to the minimum vertex cover, and thus also a constant-factor estimate of the maximum matching size, with polylogarithmic worst-case update time. Later (in SODAu002717 Proc.) they improved the approximation factor all the way to $2+eps$. Nevertheless, the longstanding fundamental problem of emph{maintaining} an approximate matching with sub-polynomial worst-case time bounds remained open. In this work we present a randomized algorithm for maintaining an emph{almost-maximal} matching in fully dynamic graphs with polylogarithmic worst-case update time. Such a matching provides $(2+eps)$-approximations for both the maximum matching and the minimum vertex cover, for any $eps u003e 0$. Our result was done independently of the SODAu002717 $(2+eps)$-approximation result of Bhattacharya et al., so it provides the first $(2+eps)$-approximation for minimum vertex cover (together with Bhattacharya et al.u0027s result) and the first $(2+eps)$-approximation for maximum (integral) matching. The worst-case update time of our algorithm, namely $O(poly(log n,eps^{-1}))$, holds deterministically, while the almost-maximality guarantee holds with high probability. Moreover, this guarantee also bounds the number of changes (replacements) to our matching in the worst-case. This result not only settles the aforementioned problem on dynamic matchings, but also provides essentially the best possible (under the unique games conjecture) approximation guarantee for dynamic vertex cover.","Title: On Finding Dense Common Subgraphs.\nYear: 2018\n\nAbstract: We study the recently introduced problem of finding dense common subgraphs: Given a sequence of graphs that share the same vertex set, the goal is to find a subset of vertices $S$ that maximizes some aggregate measure of the density of the subgraphs induced by $S$ in each of the given graphs. Different choices for the aggregation function give rise to variants of the problem that were studied recently. We settle many of the questions left open by previous works, showing NP-hardness, hardness of approximation, non-trivial approximation algorithms, and an integrality gap for a natural relaxation.","Title: On Estimating Edit Distance: Alignment, Dimension Reduction, and Embeddings.\nYear: 2018\n\nAbstract: Edit distance is a fundamental measure of distance between strings and has been widely studied in computer science. While the problem of estimating edit distance has been studied extensively, the equally important question of actually producing an alignment (i.e., the sequence of edits) has received far less attention. Somewhat surprisingly, we show that any algorithm to estimate edit distance can be used in a black-box fashion to produce an approximate alignment of strings, with modest loss in approximation factor and small loss in run time. Plugging in the result of Andoni, Krauthgamer, and Onak, we obtain an alignment that is a $(log n)^{O(1/varepsilon^2)}$ approximation in time $tilde{O}(n^{1 + varepsilon})$. Closely related to the study of approximation algorithms is the study of metric embeddings for edit distance. We show that min-hash techniques can be useful in designing edit distance embeddings through three results: (1) An embedding from Ulam distance (edit distance over permutations) to Hamming space that matches the best known distortion of $O(log n)$ and also implicitly encodes a sequence of edits between the strings; (2) In the case where the edit distance between the input strings is known to have an upper bound $K$, we show that embeddings of edit distance into Hamming space with distortion $f(n)$ can be modified in a black-box fashion to give distortion $O(f(operatorname{poly}(K)))$ for a class of periodic-free strings; (3) A randomized dimension-reduction map with contraction $c$ and asymptotically optimal expected distortion $O(c)$, improving on the previous $tilde{O}(c^{1 + 2 / log log log n})$ distortion result of Batu, Ergun, and Sahinalp.","Title: Hierarchical Clustering with Structural Constraints.\nYear: 2018\n\nAbstract: Hierarchical clustering is a popular unsupervised data analysis method. For many real-world applications, we would like to exploit prior information about the data that imposes constraints on the clustering hierarchy, and is not captured by the set of features available to the algorithm. This gives rise to the problem of clustering with structural constraints. Structural constraints pose major challenges for bottom-up approaches like average/single linkage and even though they can be naturally incorporated into top-down divisive algorithms, no formal guarantees exist on the quality of their output. In this paper, we provide provable approximation guarantees for two simple top-down algorithms, using a recently introduced optimization viewpoint of hierarchical clustering with pairwise similarity information [Dasgupta, 2016]. We show how to find good solutions even in the presence of conflicting prior information, by formulating a constraint-based regularization of the objective. We further explore a variation of this objective for dissimilarity information [Cohen-Addad et al., 2018] and improve upon current techniques. Finally, we demonstrate our approach on a real dataset for the taxonomy application.","Title: Local Density Estimation in High Dimensions.\nYear: 2018\n\nAbstract: An important question that arises in the study of high dimensional vector representations learned from data is: given a set $mathcal{D}$ of vectors and a query $q$, estimate the number of points within a specified distance threshold of $q$. We develop two estimators, LSH Count and Multi-Probe Count that use locality sensitive hashing to preprocess the data to accurately and efficiently estimate the answers to such questions via importance sampling. A key innovation is the ability to maintain a small number of hash tables via preprocessing data structures and algorithms that sample from multiple buckets in each hash table. We give bounds on the space requirements and sample complexity of our schemes, and demonstrate their effectiveness in experiments on a standard word embedding dataset.","Title: Hierarchical Clustering better than Average-Linkage.\nYear: 2019\n\nAbstract: Hierarchical Clustering (HC) is a widely studied problem in exploratory data analysis, usually tackled by simple agglomerative procedures like average-linkage, single-linkage or complete-linkage. In this paper we focus on two objectives, introduced recently to give insight into the performance of average-linkage clustering: a similarity based HC objective proposed by [21] and a dissimilarity based HC objective proposed by [9]. In both cases, we present tight counterexamples showing that average-linkage cannot obtain better than 1/3 and 2/3 approximations respectively (in the worst-case), settling an open question raised in [21]. This matches the approximation ratio of a random solution, raising a natural question: can we beat average-linkage for these objectives? We answer this in the affirmative, giving two new algorithms based on semidefinite programming with provably better guarantees.","Title: A sampling framework for counting temporal motifs.\nYear: 2018\n\nAbstract: Pattern counting in graphs is fundamental to network science tasks, and there are many scalable methods for approximating counts of small patterns, often called motifs, in large graphs. However, modern graph datasets now contain richer structure, and incorporating temporal information in particular has become a critical part of network analysis. Temporal motifs, which are generalizations of small subgraph patterns that incorporate temporal ordering on edges, are an emerging part of the network analysis toolbox. However, there are no algorithms for fast estimation of temporal motifs counts; moreover, we show that even counting simple temporal star motifs is NP-complete. Thus, there is a need for fast and approximate algorithms. Here, we present the first frequency estimation algorithms for counting temporal motifs. More specifically, we develop a sampling framework that sits as a layer on top of existing exact counting algorithms and enables fast and accurate memory-efficient estimates of temporal motif counts. Our results show that we can achieve one to two orders of magnitude speedups with minimal and controllable loss in accuracy on a number of datasets.","Title: Recovery Guarantees for Quadratic Tensors with Limited Observations.\nYear: 2018\n\nAbstract: We consider the tensor completion problem of predicting the missing entries of a tensor. The commonly used CP model has a triple product form, but an alternate family of quadratic models which are the sum of pairwise products instead of a triple product have emerged from applications such as recommendation systems. Non-convex methods are the method of choice for learning quadratic models, and this work examines their sample complexity and error guarantee. Our main result is that with the number of samples being only linear in the dimension, all local minima of the mean squared error objective are global minima and recover the original tensor. We substantiate our theoretical results with experiments on synthetic and real-world data.","Title: Efficient Density Evaluation for Smooth Kernels\nYear: 2018\n\nAbstract: Given a kernel function k(.,.) and a dataset P⊂ R^d, the kernel density function of P at a point x∈ R\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">d</sup>\n is equal to KDF\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">P</sub>\n(x):= 1/|P| Σy∈P k(x, y). Kernel density evaluation has numerous applications, in scientific computing, statistics, computer vision, machine learning and other fields. In all of them it is necessary to evaluate KDF\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">P(x)</sub>\n quickly, often for many inputs x and large point-sets P. In this paper we present a collection of algorithms for efficient KDF evaluation under the assumptions that the kernel k is \"smooth\", i.e. the value changes at most polynomially with the distance. This assumption is satisfied by several well-studied kernels, including the (generalized) t-student kernel and rational quadratic kernel. For smooth kernels, we give a data structure that, after O(dn log (Φ n)/ε^2) preprocessing, estimates KDF\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">P(x)</sub>\n up to a factor of 1 ± ε in O(dlog (Φ n)/ε\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sup>\n) time, where Phi; is the aspect ratio. The log(Φn) term can be further replaced by log n under an additional decay condition on k, which is satisfied by the aforementioned examples. We further extend the results in two ways. First, we use low-distortion embeddings to extend the results to kernels defined for spaces other than ℓ_2. The key feature of this reduction is that the distortion of the embedding affects only the running time of the algorithm, not the accuracy of the estimation. As a result, we obtain (1+ε)-approximate estimation algorithms for kernels over other ℓ\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">p</sub>\n norms, Earth-Mover Distance, and other metric spaces. Second, for smooth kernels that are decreasing with distance, we present a general reduction from density estimation to approximate near neighbor in the underlying space. This allows us to construct algorithms for general doubling metrics, as well as alternative algorithms for l\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">p</sub>\n norms and other spaces.","Title: Sampling Methods for Counting Temporal Motifs.\nYear: 2019\n\nAbstract: Pattern counting in graphs is fundamental to several network sci- ence tasks, and there is an abundance of scalable methods for estimating counts of small patterns, often called motifs, in large graphs. However, modern graph datasets now contain richer structure, and incorporating temporal information in particular has become a key part of network analysis. Consequently, temporal motifs, which are generalizations of small subgraph patterns that incorporate temporal ordering on edges, are an emerging part of the network analysis toolbox. However, there are no algorithms for fast estimation of temporal motifs counts; moreover, we show that even counting simple temporal star motifs is NP-complete. Thus, there is a need for fast and approximate algorithms. Here, we present the first frequency estimation algorithms for counting temporal motifs. More specifically, we develop a sampling framework that sits as a layer on top of existing exact counting algorithms and enables fast and accurate memory-efficient estimates of temporal motif counts. Our results show that we can achieve one to two orders of magnitude speedups over existing algorithms with minimal and controllable loss in accuracy on a number of datasets.","Title: Local Global Tradeoffs in Metric Embeddings\nYear: 2010\n\nAbstract: Suppose that every k points in a metric space X are D-distortion embeddable into \\ell _1. We give upper and lower bounds on the distortion required to embed the entire space X into \\ell _1. This is a natural mathematical question and is also motivated by the study of relaxations obtained by lift-and-project methods for graph partitioning problems. In this setting, we show that X can be embedded into \\ell _1 with distortion {\\rm O}(D \\times \\log (\\left| X \\right|/k)). Moreover, we give a lower bound showing that this result is tight if D is bounded away from 1. For D = 1 + \\delta we give a lower bound of \\Omega (\\log (\\left| X \\right|/k)/\\log (1/\\delta )); and for D = 1, we give a lower bound of \\Omega (\\log \\left| X \\right|/(\\log k + \\log \\log \\left| X \\right|)). Our bounds significantly improve on the results of Arora, Lovész, Newman, Rabani, Rabinovich and Vempala, who initiated a study of these questions.","Title: A Hitting Time Analysis of Stochastic Gradient Langevin Dynamics.\nYear: 2017\n\nAbstract: We study the Stochastic Gradient Langevin Dynamics (SGLD) algorithm for non-convex optimization. The algorithm performs stochastic gradient descent, where in each step it injects appropriately scaled Gaussian noise to the update. We analyze the algorithmu0027s hitting time to an arbitrary subset of the parameter space. Two results follow from our general theory: First, we prove that for empirical risk minimization, if the empirical risk is point-wise close to the (smooth) population risk, then the algorithm achieves an approximate local minimum of the population risk in polynomial time, escaping suboptimal local minima that only exist in the empirical risk. Second, we show that SGLD improves on one of the best known learnability results for learning linear classifiers under the zero-one loss.","Title: Multi-Commodity Flow with In-Network Processing.\nYear: 2018\n\nAbstract: Modern networks run that offer services ranging from network address translation and server load balancing to firewalls, encryption, and compression. In an industry trend known as Network Functions Virtualization (NFV), these middleboxes run as virtual machines on any commodity server, and the switches steer traffic through the relevant chain of services. Network administrators must decide how many middleboxes to run, where to place them, and how to direct traffic through them, based on the traffic load and the server and network capacity. Rather than placing specific kinds of middleboxes on each processing node, we argue that server virtualization allows each server node to host all middlebox functions, and simply vary the fraction of resources devoted to each one. This extra flexibility fundamentally changes the optimization problem the network administrators must solve to a new kind of multi-commodity flow problem, where the traffic flows consume bandwidth on the links as well as processing resources on the nodes. We show that allocating resources to maximize the processed flow can be optimized exactly via a linear programming formulation, and to arbitrary accuracy via an efficient combinatorial algorithm. Our experiments with real traffic and topologies show that a joint optimization of node and link resources leads to an efficient use of bandwidth and processing capacity. We also study a class of design problems that decide where to provide node capacity to best process and route a given set of demands, and demonstrate both approximation algorithms and hardness results for these problems.","Title: The One-Way Communication Complexity of Dynamic Time Warping Distance.\nYear: 2019\n\nAbstract: We resolve the randomized one-way communication complexity of Dynamic Time Warping (DTW) distance. We show that there is an efficient one-way communication protocol using $widetilde{O}(n/alpha)$ bits for the problem of computing an $alpha$-approximation for DTW between strings $x$ and $y$ of length $n$, and we prove a lower bound of $Omega(n / alpha)$ bits for the same problem. Our communication protocol works for strings over an arbitrary metric of polynomial size and aspect ratio, and we optimize the logarithmic factors depending on properties of the underlying metric, such as when the points are low-dimensional integer vectors equipped with various metrics or have bounded doubling dimension. We also consider linear sketches of DTW, showing that such sketches must have size $Omega(n)$.","Title: Efficient Profile Maximum Likelihood for Universal Symmetric Property Estimation.\nYear: 2019\n\nAbstract: Estimating symmetric properties of a distribution, e.g. support size, coverage, entropy, distance to uniformity, are among the most fundamental problems in algorithmic statistics. While these properties have been studied extensively and separate optimal estimators have been produced, in striking recent work Acharya et al. provided a single estimator that is competitive for each. They showed that the value of the property on the distribution that approximately maximizes profile likelihood (PML), i.e. the probability of observed frequency of frequencies, is sample competitive with respect to a broad class of estimators. Unfortunately, prior to this work, there was no known polynomial time algorithm to compute such an approximation or use PML to obtain a universal plug-in estimator. \n\nIn this paper we provide an algorithm that, given n samples from a distribution, computes an approximate PML distribution up to a multiplicative error of exp(n2/3 poly log(n)) in nearly linear time. Generalizing work of Acharya et al. we show that our algorithm yields a universal plug-in estimator that is competitive with a broad range of estimators up to accuracy є = Ω(n−0.166). Further, we provide efficient polynomial-time algorithms for computing a d-dimensional generalization of PML (for constant d) that allows for universal plug-in estimation of symmetric relationships between distributions.","Title: Rehashing Kernel Evaluation in High Dimensions\nYear: 2019\n\nAbstract: Kernel methods are effective but do not scale well to large scale data, especially in high dimensions where the geometric data structures used to accelerate kernel evaluation suffer from the curse of dimensionality. Recent theoretical advances have proposed fast kernel evaluation algorithms leveraging hashing techniques with worst-case asymptotic improvements. However, these advances are largely confined to the theoretical realm due to concerns such as super-linear preprocessing time and diminishing gains in non-worst case datasets. In this paper, we close the gap between theory and practice by addressing these challenges via provable and practical procedures for adaptive sample size selection, preprocessing time reduction, and refined variance bounds that quantify the data-dependent performance of random sampling and hashing-based kernel evaluation methods. Our experiments show that these new tools offer up to $10\\times$ improvement in evaluation time on a range of synthetic and real-world datasets.","Title: Brief Announcement: A Randomness-efficient Massively Parallel Algorithm for Connectivity\nYear: 2021\n\nAbstract: ABSTRACTWe give a randomness-efficient Massively Parallel Computation (MPC) algorithm for deciding whether an undirected graph is connected. For Connectivity on n-vertex, m-edge graphs whose components have diameter at most D = 2o(log n/ log log n), our algorithm runs in R = O(log D + log logm/n,.n) rounds and uses a total of (log n)O(R) random bits, O(m) machines, and n1-Ω(1) space per machine with good probability.1 With good probability means with probability at least 1 - 1/poly ((m log n)/n), which is the same as in Liu, Tarjan, and Zhong (SPAA '20). Our algorithm achieves a super-polynomial saving in randomness complexity as compared to the breakthrough algorithm of Andoni et al. (FOCS '18) and the subsequent improvement by Behnezhad et al. (FOCS '19). Our algorithm has the same round complexity as that of Behnezhad et al., but uses more total space. Our Connectivity algorithm is an instantiation of a general method we develop for converting randomized algorithms in the PRAM model to highly randomness-efficient MPC algorithms. We show that for k = o(log n/log log n) and p = nO(1), any time-k p-processor randomized PRAM algorithm computing a function on n input bits can be converted to an equivalent strongly sublinear MPC algorithm with O(k) rounds and only a total of (log n)O(k) random bits. Our Connectivity algorithm follows from applying this method to the recent CRCW PRAM algorithm of Liu, Tarjan, and Zhong (SPAA '20). Our approach is based on the design of a pseudorandom generator for PRAM algorithms. The analysis of our generator is built on classic and influential results in circuit complexity (Hå stad '86; Nisan and Wigderson '88), which we generalize from the setting of small-depth circuits to the more powerful setting of PRAM algorithms. The parameters that we achieve are optimal given the current state of the art in complexity theory, in the sense that further improvements will imply ≠ NC1.","Title: Metric Distortion Bounds for Randomized Social Choice\nYear: 2022\n\nAbstract: Consider the following social choice problem. Suppose we have a set of $n$ voters and $m$ candidates that lie in a metric space. The goal is to design a mechanism to choose a candidate whose average distance to the voters is as small as possible. However, the mechanism does not get direct access to the metric space. Instead, it gets each voter's ordinal ranking of the candidates by distance. Given only this partial information, what is the smallest worst-case approximation ratio (known as the distortion) that a mechanism can guarantee? A simple example shows that no deterministic mechanism can guarantee distortion better than $3$, and no randomized mechanism can guarantee distortion better than $2$. It has been conjectured that both of these lower bounds are optimal, and recently, Gkatzelis, Halpern, and Shah proved this conjecture for deterministic mechanisms. We disprove the conjecture for randomized mechanisms for $m \\geq 3$ by constructing elections for which no randomized mechanism can guarantee distortion better than $2.0261$ for $m = 3$, $2.0496$ for $m = 4$, up to $2.1126$ as $m \\to \\infty$. We obtain our lower bounds by identifying a class of simple metrics that appear to capture much of the hardness of the problem, and we show that any randomized mechanism must have high distortion on one of these metrics. We provide a nearly matching upper bound for this restricted class of metrics as well. Finally, we conjecture that these bounds give the optimal distortion for every $m$, and provide a proof for $m = 3$, thereby resolving that case.","Title: Polylogarithmic Sketches for Clustering\nYear: 2022\n\nAbstract: Given $n$ points in $\\ell_p^d$, we consider the problem of partitioning points into $k$ clusters with associated centers. The cost of a clustering is the sum of $p^{\\text{th}}$ powers of distances of points to their cluster centers. For $p \\in [1,2]$, we design sketches of size poly$(\\log(nd),k,1/\\epsilon)$ such that the cost of the optimal clustering can be estimated to within factor $1+\\epsilon$, despite the fact that the compressed representation does not contain enough information to recover the cluster centers or the partition into clusters. This leads to a streaming algorithm for estimating the clustering cost with space poly$(\\log(nd),k,1/\\epsilon)$. We also obtain a distributed memory algorithm, where the $n$ points are arbitrarily partitioned amongst $m$ machines, each of which sends information to a central party who then computes an approximation of the clustering cost. Prior to this work, no such streaming or distributed-memory algorithm was known with sublinear dependence on $d$ for $p \\in [1,2)$.","Title: Almost 3-Approximate Correlation Clustering in Constant Rounds\nYear: 2022\n\nAbstract: We study parallel algorithms for correlation clustering. Each pair among n objects is labeled as either “similar” or “dissimilar”. The goal is to partition the objects into arbitrarily many clusters while minimizing the number of disagreements with the labels.Our main result is an algorithm that for any $\\varepsilon>0$ obtains a (3 + $\\varepsilon$)-approximation in $O(1/\\varepsilon$) rounds (of models such as massively parallel computation, local, and semi-streaming). This is a culminating point for the rich literature on parallel correlation clustering. On the one hand, the approximation (almost) matches a natural barrier of 3 for combinatorial algorithms. On the other hand, the algorithm’s round-complexity is essentially constant.To achieve this result, we introduce a simple $O(1/\\varepsilon$)-round parallel algorithm. Our main result is to provide an analysis of this algorithm, showing that it achieves a (3 + $\\varepsilon$)-approximation. Our analysis draws on new connections to sublinear-time algorithms. Specifically, it builds on the work of Yoshida, Yamamoto, and Ito [1] on bounding the “query complexity” of greedy maximal independent set. To our knowledge, this is the first application of this method in analyzing the approximation ratio of any algorithm.Full version. Due to the page limit, this version of the paper does not include all the proofs. The full version of the paper is available at [2]."],"string":"[\n \"Title: Better algorithms and hardness for broadcast scheduling via a discrepancy approach\\nYear: 2014\\n\\nAbstract: We study the broadcast scheduling problem with the objective of minimizing the average response time. There is a single server that can hold n pages of unit size, and multiple requests for these pages arrive over time. At each time slot the server can broadcast one page which satisfies all the outstanding requests for this page at that time. The goal is to find a schedule to minimize the average response time of the requests, i.e. the duration since a request arrives until it is satisfied. We give an Õ(log1.5 n) approximation algorithm for the problem improving upon the previous Õ(log2 n) approximation. We also show an Ω(log1/2-ε n) hardness result, and an integrality gap of Ω(log n) for the natural LP relaxation for the problem. Prior to our work, only NP-Hardness and a (tiny) constant integrality gap was known. These results are based on establishing a close connection to the discrepancy minimization problem for permutation set-systems. Specifically, our improved approximation is based on using recent algorithmic ideas developed for discrepancy minimization. Our integrality gap is obtained from the Ω(log n)-lower bound on the discrepancy of 3-permutations, while our hardness result is based on establishing the first hardness result for the discrepancy of ℓ-permutations.\",\n \"Title: Uniqueness of Tensor Decompositions with Applications to Polynomial Identifiability\\nYear: 2013\\n\\nAbstract: We give a robust version of the celebrated result of Kruskal on the uniqueness of tensor decompositions: we prove that given a tensor whose decomposition satisfies a robust form of Kruskal's rank condition, it is possible to approximately recover the decomposition if the tensor is known up to a sufficiently small (inverse polynomial) error. Kruskal's theorem has found many applications in proving the identifiability of parameters for various latent variable models and mixture models such as Hidden Markov models, topic models etc. Our robust version immediately implies identifiability using only polynomially many samples in many of these settings. This polynomial identifiability is an essential first step towards efficient learning algorithms for these models. Recently, algorithms based on tensor decompositions have been used to estimate the parameters of various hidden variable models efficiently in special cases as long as they satisfy certain \\\"non-degeneracy\\\" properties. Our methods give a way to go beyond this non-degeneracy barrier, and establish polynomial identifiability of the parameters under much milder conditions. Given the importance of Kruskal's theorem in the tensor literature, we expect that this robust version will have several applications beyond the settings we explore in this work.\",\n \"Title: Improved Approximation Algorithms for Label Cover Problems\\nYear: 2011\\n\\nAbstract: In this paper we consider both the maximization variant Max Rep and the minimization variant Min Rep of the famous Label Cover problem. So far the best approximation ratios known for these two problems were $O(\\\\\\\\sqrt{n})$ and indeed some authors suggested the possibility that this ratio is the best approximation factor for these two problems. We show, in fact, that there are a O(n1/3)-approximation algorithm for Max Rep and a O(n1/3log¿2/3n)-approximation algorithm for Min Rep. In addition, we also exhibit a randomized reduction from Densestk-Subgraph to Max Rep, showing that any approximation factor for Max Rep implies the same factor (up to a constant) for Densestk-Subgraph.\",\n \"Title: On the Advantage over Random for Maximum Acyclic Subgraph\\nYear: 2007\\n\\nAbstract: In this paper we present a new approximation algorithm for the MAX ACYCLIC SUBGRAPH problem. Given an instance where the maximum acyclic subgraph contains 1/2 + \\\\delta fraction of all edges, our algorithm finds an acyclic subgraph with 1/2 + \\\\Omega (\\\\delta /\\\\log n) fraction of all edges.\",\n \"Title: Combinatorial feature selection problems\\nYear: 2000\\n\\nAbstract: Motivated by frequently recurring themes in information retrieval and related disciplines, we define a genre of problems called combinatorial feature selection problems. Given a set S of multidimensional objects, the goal is to select a subset K of relevant dimensions (or features) such that some desired property /spl Pi/ holds for the set S restricted to K. Depending on /spl Pi/, the goal could be to either maximize or minimize the size of the subset K. Several well-studied feature selection problems can be cast in this form. We study the problems in this class derived from several natural and interesting properties /spl Pi/, including variants of the classical p-center problem as well as problems akin to determining the VC-dimension of a set system. Our main contribution is a theoretical framework for studying combinatorial feature selection, providing (in most cases essentially tight) approximation algorithms and hardness results for several instances of these problems.\",\n \"Title: Clustering with Qualitative Information\\nYear: 2005\\n\\nAbstract: We consider the problem of clustering a collection of elements based on pairwise judgments of similarity and dissimilarity. Bansal, Blum and Chawla [1] cast the problem thus: given a graph G whose edges are labeled \\\"+\\\" (similar) or \\\"-\\\" (dissimilar), partition the vertices into clusters so that the number of pairs correctly (resp. incorrectly) classified with respect to the input labeling is maximized (resp. minimized). Complete graphs, where the classifier labelsevery edge, and general graphs, where some edges are not labeled, are both worth studying. We answer several questions left open in [1] and provide a sound overview of clustering with qualitative information.We give a factor 4 approximation for minimization on complete graphs, and a factor O(log n) approximation for general graphs. For the maximization version, a PTAS for complete graphs is shown in [1]; we give a factor 0.7664 approximation for general graphs, noting that a PTAS is unlikely by proving APX-hardness. We also prove the APX-hardness of minimization on complete graphs.\",\n \"Title: Constrained TSP and Low-Power Computing\\nYear: 1997\\n\\nAbstract: In the precedence-constrained traveling salesman problem (PTSP ) we are given a partial order on nodes, each of which is labeled by one of points in a metric space. We are to find a visit order consistent with the precedence constraints that minimizes the total cost of the corresponding path in th e metric space. We give negative results on approximability by relating the proble m to the Shortest Com- mon Supersequence problem, helping to explain why there has been very little successin approximation algorithms for this problem. We also give approximation algorithms for a number of special cases, included cases appropriate for a problem in low-power computing; in the process, we show that algorithms for the -server problem and the traveling salesman problem can be used to derive approxima- tion algorithms for the PTSP. We give tight bounds on the approximation ratios achieved by natural classes of algorithms for this optimiza tion problem (which include algorithms proposed and used in empirical studies of this problem). We briefly summarize results of experiments with several algor ithms on a standard set of compiler benchmarks, comparing several known and new algorithms.\",\n \"Title: Min-wise independent permutations\\nYear: 2000\\n\\nAbstract: Abstract We define and study the notion of min-wise independent families of permutations. We say that F⊆ Sn is min-wise independent if for any set X ⊆ [n] and any x ∈ X ,w henπ is chosen at random in F we have Pr(min{π(X)} = π(x)) = 1\",\n \"Title: Note on MAX 2SAT\\nYear: 2006\\n\\nAbstract: Abstract In this note we present an approximation algorithm for MAX 2SAT that given a (1 \\\") satisfiable instance finds an assignment of variables satisfying a 1 O( p \\\" ) fraction of all constraints. This result is optimal assuming the Unique Games Conjecture. The best previously known result, due to Zwick, was 1 O(\\\",/3). We believe that the analysis of our algorithm is much simpler than the analysis of Zwick’s algorithm.\",\n \"Title: Minimizing wirelength in zero and bounded skew clock trees\\nYear: 2004\\n\\nAbstract: An important problem in VLSI design is distributing a clock signal to svnchronous elements in a VLSI circuit so that the signal arrives at ail elements simultaneously. The signai is distributed 6y means of a clock routing tree rooted at a global clock source. The difference in length between the longest and shortest root-leaf path is called the skav of the tree. The problem is to construct a clock tree with zero skew (to achieve synchronicity) and minimal sum of edge lengths (so that circuit area and clock tree capacitance are minimized). We give the first constant-factor approximation algorithms for this problem and its variants that arise in the VLSI context. For the zero skew problem in genera1 metric spaces, we give an approximation algorithm with a performance guarantee of 2e. For the L1 version on the plane, we give an (8/ In 2)-approximation algorithm.\",\n \"Title: The dynamic servers problem\\nYear: 1998\\n\\nAbstract: We present a generalization of the k-server problem, calleddynamic servers, where the number of servers is not fixed apriori; rather, the algorithm is free to increase and decreasethe number of servers at will, but it is required to pay arental cost for each active server at designated times. Thisnew problem is a simultaneous abstraction for problems arisingin a variety of applications, particularly the informationdelivery problem for video-on-demand, web server management,and the...\",\n \"Title: Filtering Image Spam with Near-Duplicate Detection\\nYear: 2007\\n\\nAbstract: A new trend in email spam is the emergence of image spam. Although current anti-spam tech- nologies are quite successful in filtering text-based spam emails, the new image spams are substan- tially more dicult to detect, as they employ a variety of image creation and randomization al- gorithms. Spam image creation algorithms are designed to defeat well-known vision algorithms such as optical character recognition (OCR) al- gorithms whereas randomization techniques en- sure the uniqueness of each image. We observe that image spam is often sent in batches that con- sist of visually similar images that dier only due to the application of randomization algorithms. Based on this observation, we propose an image spam detection system that uses near-duplicate detection to detect spam images. We rely on traditional anti-spam methods to detect a sub- set of spam images and then use multiple image spam filters to detect all the spam images that \\\"look\\\" like the spam caught by traditional meth- ods. We have implemented a prototype system to achieve high detection rate while having a less than 0.001% false positive rate.\",\n \"Title: On targeting Markov segments\\nYear: 1999\\n\\nAbstract: Consider two user populations, of which one is targeted and the other is not. Users in the targeted population follow a Markov chain on a space of states. The un- targeted population follows another Markov chain, also defined on the same set of states. Each time a user ar- rives at a state, he/she is presented with information ap- propriate for the targeted population (an advertisement, or a recommendation) with some probability. Present- ing the advertisement incurs a cost. Notice that while the revenue grows in proportion to the flow of targeted users through the state, the cost grows in proportion to the total flow (targeted and untargeted) through the state. How can we compute the best advertisement pol- icy? The world-wide web is a natural setting for such a problem. Internet service providers have trail informa- tion for building such Markovian user models where states correspond to pages on the web. In this paper we study the simple problem above, as well as the vari- ants with multiple targetable segments. In some set- tings the policy need not be a static probability distri- bution on states. Instead, we can dynamically vary the policy based on the user's path through the states.\",\n \"Title: Efficiently matching sets of features with random histograms\\nYear: 2008\\n\\nAbstract: As the commonly used representation of a feature-rich data object has evolved from a single feature vector to a set of feature vectors, a key challenge in building a content-based search engine for feature-rich data is to match feature-sets efficiently. Although substantial progress has been made during the past few years, existing approaches are still inefficient and inflexible for building a search engine for massive datasets. This paper presents a randomized algorithm to embed a set of features into a single high-dimensional vector to simplify the feature-set matching problem. The main idea is to project feature vectors into an auxiliary space using locality sensitive hashing and to represent a set of features as a histogram in the auxiliary space. A histogram is simply a high dimensional vector, and efficient similarity measures like L1 and L2 distances can be employed to approximate feature-set distance measures. We evaluated the proposed approach under three different task settings, i.e. content-based image search, image object recognition and near-duplicate video clip detection. The experimental results show that the proposed approach is indeed effective and flexible. It can achieve accuracy comparable to the feature-set matching methods, while requiring significantly less space and time. For object recognition with Caltech 101 dataset, our method runs 25 times faster to achieve the same precision as Pyramid Matching Kernel, the state-of-the-art feature-set matching method.\",\n \"Title: On semidefinite programming relaxations for graph coloring and vertex cover\\nYear: 2002\\n\\nAbstract: We investigate the power of a strengthened SDP relaxation for graph coloring whose value is equal to a variant of the Lovász ϑ-function. We show families of graphs where the value of the relaxation is 2 + ε for any fixed ε 0, yet the chromatic number is nδ for some fixed δ 0, which is a function of ε. This demonstrates the bound provided by the SDP is not strong enough to color a 3-colorable graph with no(1) colors.Kleinberg and Goemans considered an SDP relaxation for vertex cover whose value is n - ϑ1/2 (ϑ1/2 being the variant of the ϑ-function introduced by Schrijver). They asked whether this is within a ratio of 2 - ε of the optimal vertex cover for any ε 0. Our construction answers this question negatively.\",\n \"Title: Multi-probe LSH: efficient indexing for high-dimensional similarity search\\nYear: 2007\\n\\nAbstract: Similarity indices for high-dimensional data are very desirable for building content-based search systems for feature-rich data such as audio, images, videos, and other sensor data. Recently, locality sensitive hashing (LSH) and its variations have been proposed as indexing techniques for approximate similarity search. A significant drawback of these approaches is the requirement for a large number of hash tables in order to achieve good search quality. This paper proposes a new indexing scheme called multi-probe LSH that overcomes this drawback. Multi-probe LSH is built on the well-known LSH technique, but it intelligently probes multiple buckets that are likely to contain query results in a hash table. Our method is inspired by and improves upon recent theoretical work on entropy-based LSH designed to reduce the space requirement of the basic LSH method. We have implemented the multi-probe LSH method and evaluated the implementation with two different high-dimensional datasets. Our evaluation shows that the multi-probe LSH method substantially improves upon previously proposed methods in both space and time efficiency. To achieve the same search quality, multi-probe LSH has a similar time-efficiency as the basic LSH method while reducing the number of hash tables by an order of magnitude. In comparison with the entropy-based LSH method, to achieve the same search quality, multi-probe LSH uses less query time and 5 to 8 times fewer number of hash tables.\",\n \"Title: Near-optimal algorithms for unique games\\nYear: 2006\\n\\nAbstract: Unique games are constraint satisfaction problems that can be viewed as a generalization of Max-Cut to a larger domain size. The Unique Games Conjecture states that it is hard to distinguish between instances of unique games where almost all constraints are satisfiable and those where almost none are satisfiable. It has been shown to imply a number of inapproximability results for fundamental problems that seem difficult to obtain by more standard complexity assumptions. Thus, proving or refuting this conjecture is an important goal. We present significantly improved approximation algorithms for unique games. For instances with domain size k where the optimal solution satisfies 1-ε fraction of all constraints, our algorithms satisfy roughly k-ε/(2-ε) and 1- O(√εlog k) fraction of all constraints. Our algorithms are based on rounding a natural semidefinite programming relaxation for the problem and their performance almost matches the integrality gap of this relaxation. Our results are near optimal if the Unique Games Conjecture is true, i.e. any improvement (beyond low order terms) would refute the conjecture.\",\n \"Title: A constant-factor approximation algorithm for the k-median problem\\nYear: 2002\\n\\nAbstract: We present the first constant-factor approximation algorithm for the metric k-median problem. The k-median problem is one of the most well-studied clustering problems, i.e., those problems in which the aim is to partition a given set of points into clusters so that the points within a cluster are relatively close with respect to some measure. For the metric k-median problem, we are given n points in a metric space. We select k of these to be cluster centers and then assign each point to its closest selected center. If point j is assigned to a center i, the cost incurred is proportional to the distance between i and j. The goal is to select the k centers that minimize the sum of the assignment costs. We give a 62/3-approximation algorithm for this problem. This improves upon the best previously known result of O(log k log log k), which was obtained by refining and derandomizing a randomized O(log n log log n)-approximation algorithm of Bartal.\",\n \"Title: Aggregating inconsistent information: ranking and clustering\\nYear: 2005\\n\\nAbstract: We address optimization problems in which we are given contradictory pieces of input information and the goal is to find a globally consistent solution that minimizes the number of disagreements with the respective inputs. Specifically, the problems we address are rank aggregation, the feedback arc set problem on tournaments, and correlation and consensus clustering. We show that for all these problems (and various weighted versions of them), we can obtain improved approximation factors using essentially the same remarkably simple algorithm. Additionally, we almost settle a long-standing conjecture of Bang-Jensen and Thomassen and show that unless NP⊆BPP, there is no polynomial time algorithm for the problem of minimum feedback arc set in tournaments.\",\n \"Title: Approximating the average response time in broadcast scheduling\\nYear: 2005\\n\\nAbstract: We consider the problem of approximating the minimum average response time in on-demand data broadcasting systems. The best approximation factors known for this problem involve resource augmentation. We provide the first non-trivial approximation factors in the absence of resource augmentation, achieving an additive O(√n)-approximation, where n is the number of distinct pages. Our result can be extended, for any ε 0, to a (1 + ε)-speed, additive O(1/ε)-approximation algorithm. Prior to our work, no non-trivial approximation factor was known for the case of ε\",\n \"Title: Embedding the Ulam metric into l1\\nYear: 2006\\n\\nAbstract: Edit distance is a fundamental measure of distance between strings, the ex- tensive study of which has recently focused on computational problems such as nearest neighbor search, sketching and fast approximation. A very powerful paradigm is to map the metric space induced by the edit distance into a normed space (e. g., '1) with small dis- tortion, and then use the rich algorithmic toolkit known for normed spaces. Although the minimum distortion required to embed edit distance into '1 has received a lot of attention lately, there is a large gap between known upper and lower bounds. We make progress on this question by considering large, well-structured submetrics of the edit distance metric space. Our main technical result is that the Ulam metric, namely, the edit distance on permu- tations of length at most n, embeds into '1 with distortion O(log n). This immediately leads to sketching algorithms with constant size sketches, and to efficient approximate nearest neighbor search algorithms, with approximation factor O(log n). The embedding and its algorithmic consequences present a big improvement over those previously known for the Ulam metric, and they are significantly better than the state of the art for edit distance in general. Further, we extend these results for the Ulam metric to edit distance on strings that are (locally) non-repetitive, i. e., strings where (close by) substrings are distinct.\",\n \"Title: Polynomial integrality gaps for strong SDP relaxations of Densest k-subgraph\\nYear: 2012\\n\\nAbstract: The Densest k-subgraph problem (i.e. find a size k subgraph with maximum number of edges), is one of the notorious problems in approximation algorithms. There is a significant gap between known upper and lower bounds for Densest k-subgraph: the current best algorithm gives an ≈ O(n1/4) approximation, while even showing a small constant factor hardness requires significantly stronger assumptions than P ≠ NP. In addition to interest in designing better algorithms, a number of recent results have exploited the conjectured hardness of Densest k-subgraph and its variants. Thus, understanding the approximability of Densest k-subgraph is an important challenge. In this work, we give evidence for the hardness of approximating Densest k-subgraph within polynomial factors. Specifically, we expose the limitations of strong semidefinite programs from SDP hierarchies in solving Densest k-subgraph. Our results include: • A lower bound of Ω(n1/4/log3 n) on the integrality gap for Ω(log n/log log n) rounds of the Sherali-Adams relaxation for Densest k-subgraph. This also holds for the relaxation obtained from Sherali-Adams with an added SDP constraint. Our gap instances are in fact Erdös-Renyi random graphs. • For every ε 0, a lower bound of n2/53−ε on the integrality gap of nΩ(ε) rounds of the Lasserre SDP relaxation for Densest k-subgraph, and an nΩε(1) gap for n1−ε rounds. Our construction proceeds via a reduction from random instances of a certain Max-CSP over large domains. In the absence of inapproximability results for Densest k-subgraph, our results show that beating a factor of nΩ(1) is a barrier for even the most powerful SDPs, and in fact even beating the best known n1/4 factor is a barrier for current techniques. Our results indicate that approximating Densest k-subgraph within a polynomial factor might be a harder problem than Unique Games or Small Set Expansion, since these problems were recently shown to be solvable using nεΩ(1) rounds of the Lasserre hierarchy, where ε is the completeness parameter in Unique Games and Small Set Expansion.\",\n \"Title: A divide and conquer algorithm for d-dimensional arrangement\\nYear: 2007\\n\\nAbstract: We give an O(√log n)-approximation algorithm for d-dimensional arrangement - the problem of mapping a graph to a d-dimensional grid (for constant d ≥ 2) to minimize the sum of edge lengths. This improves the previous best O(log n log log n) approximation of Even, Naor, Rao and Schieber. The d = 1 case is the well studied Minimum Linear Arrangement problem. The problem is equivalent to the question of mapping a graph to integer points on a line so as to minimize the sum of edge costs, where edge costs are measured by edge lengths raised to the exponent α = 1/d. We give a simple recursive partitioning algorithm for this variant of linear arrangement for any exponent α ε (0, 1). Our analysis also applies to a directed version of the problem: given a directed graph, the goal is to map vertices to the line so as to minimize the sum of costs of forward edges. As before, edge costs are edge lengths raised to the exponent α. The α = 0 case is the well known Minimum Feedback Arc Set problem, and the α = 1 case is essentially the Minimum Storage-Time Product problem. We analyze an extremely simple divide and conquer algorithm that uses a balanced cut subroutine with approximation ratio β to recursively partition the graph. Our analysis shows that this approach gives an approximation ratio of O(β) for the minimum linear arrangement problem with exponent α for any fixed α ε (0, 1).\",\n \"Title: On the Integrality Ratio for Asymmetric TSP\\nYear: 2004\\n\\nAbstract: We improve the lower bound on the integrality ratio of the Held-Karp bound for asymmetric TSP (with triangle inequality) from 4/3 to 2.\",\n \"Title: High-confidence near-duplicate image detection\\nYear: 2012\\n\\nAbstract: In this paper, we propose two techniques for near-duplicate image detection at high confidence and large scale. First, we show that entropy-based filtering eliminates ambiguous SIFT features that cause most of the false positives, and enables claiming near-duplicity with a single match of the retained high-quality features. Second, we show that graph cut can be used for query expansion with a duplicity graph computed offline to substantially improve search quality. Evaluation with web images show that when combined with sketch embedding [6], our methods achieve false positive rate orders of magnitude lower than the standard visual word approach. We demonstrate the proposed techniques with a large-scale image search engine which, using indexing data structure offline computed with a Hadoop cluster, is capable of serving more than 50 million web images with a single commodity server.\",\n \"Title: On non-uniform multicommodity buy-at-bulk network design\\nYear: 2005\\n\\nAbstract: We study the multicommodity buy-at-bulk network design problem in which we seek to design a network that satisfies the demands between terminals from a given set of source-sink pairs. The key characteristic of this problem is the fact that the cost functions associated with the edges of the graph are sub-additive monotone and hence experience economies of scale. In the non-uniform case, each edge has its own cost function -- possibly different from other edges. Special cases of this problem have been studied extensively: there are approximation algorithms when the edge cost functions are identical or when all source-sink pairs share the same source. We present the first non-trivial approximation algorithm for the general case. Our algorithm is an extremely simple randomized greedy algorithm and has an approximation guarantee of exp(O√ln n ln ln n)) when the instance has at most n source-sink pairs with unit demands. In the case of general demands, this yields an approximation factor of exp(O √ln N ln ln N)), where N is the sum of all demands.\",\n \"Title: On quadratic programming with a ratio objective\\nYear: 2012\\n\\nAbstract: Quadratic Programming (QP) is the well-studied problem of maximizing over {−1,1} values the quadratic form ∑i≠jaijxixj. QP captures many known combinatorial optimization problems, and assuming the Unique Games conjecture, Semidefinite Programming (SDP) techniques give optimal approximation algorithms. We extend this body of work by initiating the study of Quadratic Programming problems where the variables take values in the domain {−1,0,1}. The specific problem we study is $$\\\\begin{aligned} \\\\textsf{QP-Ratio} &: \\\\mbox{\\\\ \\\\ } \\\\max_{\\\\{-1,0,1\\\\}^n} \\\\frac{\\\\sum_{i \\\\not = j} a_{ij} x_i x_j}{\\\\sum x_i^2} \\\\end{aligned}$$ This is a natural relative of several well studied problems (in fact Trevisan introduced a normalized variant as a stepping stone towards a spectral algorithm for Max Cut Gain). Quadratic ratio problems are good testbeds for both algorithms and complexity because the techniques used for quadratic problems for the {−1,1} and {0,1} domains do not seem to carry over to the {−1,0,1} domain. We give approximation algorithms and evidence for the hardness of approximating these problems. We consider an SDP relaxation obtained by adding constraints to the natural eigenvalue (or SDP) relaxation for this problem. Using this, we obtain an $\\\\tilde{O}(n^{1/3})$ approximation algorithm for QP-ratio. We also give a $\\\\tilde{O}(n^{1/4})$ approximation for bipartite graphs, and better algorithms for special cases. As with other problems with ratio objectives (e.g. uniform sparsest cut), it seems difficult to obtain inapproximability results based on P ≠NP . We give two results that indicate that QP-Ratio is hard to approximate to within any constant factor: one is based on the assumption that random instances of Max k-AND are hard to approximate, and the other makes a connection to a ratio version of Unique Games. We also give a natural distribution on instances of QP-Ratio for which an nε approximation (for ε roughly 1/10) seems out of reach of current techniques.\",\n \"Title: Improved Combinatorial Algorithms for the Facility Location and k-Median Problems\\nYear: 1999\\n\\nAbstract: We present improved combinatorial approximation algorithms for the uncapacitated facility location and k-median problems. Two central ideas in most of our results are cost scaling and greedy improvement. We present a simple greedy local search algorithm which achieves an approximation ratio of \\\\math in \\\\math time. This also yields a bicriteria approximation tradeoff of \\\\math for facility cost versus service cost which is better than previously known tradeoffs and close to the best possible. Combining greedy improvement and cost scaling with a recent primal dual algorithm for facility location due to Jain and Vazirani, we get an approximation ratio of 1.853 in \\\\math time. This is already very close to the approximation guarantee of the best known algorithm which is LP-based. Further, combined with the best known LP-based algorithm for facility location, we get a very slight improvement in the approximation factor for facility location, achieving 1.728. We present improved approximation algorithms for capacitated facility location and a variant.We also present a 4-approximation for the k-median problem, using similar ideas, building on the 6-approximation of Jain and Vazirani. The algorithm runs in \\\\math time.\",\n \"Title: A robust maximum completion time measure for scheduling\\nYear: 2006\\n\\nAbstract: One popular measure for evaluating the performance of scheduling algorithms, is the maximum response time of any job (makespan). Typically the objective is to find a schedule that minimizes the maximum response time over all jobs. One drawback of this measure is that a relatively small number of jobs in the request set could cause the maximum response time to be very high. Thus, this measure reflects local rather than global properties of the request set. In this paper we consider a robust generalization of this measure. Our goal is to minimize T, such that a given fraction of jobs can be scheduled with a response time of at most T. We demonstrate the applicability of this measure in the context of broadcast scheduling. We show that in the online setting no constant factor online approximation is possible for the problem of minimizing the maximum response time for a given fraction of jobs in the context of broadcast scheduling. We give a factor 5, polynomial time offline approximation algorithm for the problem of minimizing the maximum response time for a given fraction of jobs in the context of broadcast scheduling.\",\n \"Title: Ferret: a toolkit for content-based similarity search of feature-rich data\\nYear: 2006\\n\\nAbstract: Building content-based search tools for feature-rich data has been a challenging problem because feature-rich data such as audio recordings, digital images, and sensor data are inherently noisy and high dimensional. Comparing noisy data requires comparisons based on similarity instead of exact matches, and thus searching for noisy data requires similarity search instead of exact search.The Ferret toolkit is designed to help system builders quickly construct content-based similarity search systems for feature-rich data types. The key component of the toolkit is a content-based similarity search engine for generic, multi-feature object representations. To solve the similarity search problem in high-dimensional spaces, we have developed approximation methods inspired by recent theoretical results on dimension reduction. The search engine constructs sketches from feature vectors as highly compact data structures for matching, filtering and ranking data objects. The toolkit also includes several other components to help system builders address search system infrastructure issues. We have implemented the toolkit and used it to successfully construct content-based similarity search systems for four data types: audio recordings, digital photos, 3D shape models and genomic microarray data.\",\n \"Title: MaxMin allocation via degree lower-bounded arborescences\\nYear: 2009\\n\\nAbstract: We consider the problem of MaxMin allocation of indivisible goods. There are m items to be distributed among n players. Each player $i$ has a nonnegative valuation pij for an item j, and the goal is to allocate items to players so as to maximize the minimum total valuation received by each player. There is a large gap in our understanding of this problem. The best known positive result is an ~O(√ n)-approximation algorithm, while there is only a factor 2 hardness known. Better algorithms are known for the restricted assignment case where each item has exactly one nonzero value for the players. We study the effect of bounded degree for items: each item has a nonzero value for at most D players. We show that essentially the case D = 3 is equivalent to the general case, and give a 4-approximation algorithm for D = 2. The current algorithmic results for MaxMin Allocation are based on a complicated LP relaxation called the configuration LP. We present a much simpler LP which is equivalent in power to the configuration LP. We focus on a special case of MaxMin Allocation-a family of instances on which this LP has a polynomially large gap. The technical core of our result for this case comes from an algorithm for an interesting new optimization problem on directed graphs, MaxMinDegree Arborescence, where the goal is to produce an arborescence of large outdegree. We develop an nε-approximation for this problem that runs in nO(1/ε) time and obtain a a polylogarithmic approximation that runs in quasipolynomial time, using a lift-and-project inspired LP formulation. In fact, we show that our results imply a rounding algorithm for the relaxations obtained by t rounds of the Sherali-Adams hierarchy applied to a natural LP relaxation of the problem. Roughly speaking, the integrality gap of the relaxation obtained from t rounds of Sherali-Adams is at most n1/t. We are able to extend the latter result to a more general class of instances. Along the way, we prove a result about the existence of a perfect matching in a probabilistically pruned graph which may be of independent interest.\",\n \"Title: On-line load balancing for related machines\\nYear: 1997\\n\\nAbstract: We consider the problem of scheduling permanent jobs on related machines in anon-line fashion. We design a new algorithm that achieves the competitive ratio of 3+p8 5:828 for the deterministic version, and 3:31= ln 2:155 4:311 for its randomizedvariant, improving the previous competitive ratios of 8 and 2e 5:436. We also provelower bounds of 2:4380 on the competitive ratio of deterministic algorithms and 1:8372on the competitive ratio of randomized algorithms for this problem.Dept....\",\n \"Title: Finding frequent items in data streams\\nYear: 2004\\n\\nAbstract: We present a 1-pass algorithm for estimating the most frequent items in a data stream using limited storage space. Our method relies on a data structure called a COUNT SKETCH, which allows us to reliably estimate the frequencies of frequent items in the stream. Our algorithm achieves better space bounds than the previously known best algorithms for this problem for several natural distributions on the item frequencies. In addition, our algorithm leads directly to a 2-pass algorithm for the problem of estimating the items with the largest (absolute) change in frequency between two data streams. To our knowledge, this latter problem has not been previously studied in the literature.\",\n \"Title: Sizing sketches: a rank-based analysis for similarity search\\nYear: 2007\\n\\nAbstract: Sketches are compact data structures that can be used to estimate properties of the original data in building large-scale search engines and data analysis systems. Recent theoretical and experimental studies have shown that sketches constructed from feature vectors using randomized projections can effectively approximate L1 distance on the feature vectors with the Hamming distance on their sketches. Furthermore, such sketches can achieve good filtering accuracy while reducing the metadata space requirement and speeding up similarity searches by an order of magnitude. However, it is not clear how to choose the size of the sketches since it depends ondata type, dataset size, and desired filtering quality. In real systems designs, it is necessary to understand how to choose sketch size without the dataset, or at least without the whole datase. This paper presents an analytical model and experimental results to help system designers make such design decisions. We present arank-based filtering model that describes the relationship between sketch size and data set size based on the dataset distance distribution. Our experimental results with several datasets including images, audio, and 3D shapes show that the model yields good, conservative predictions. We show that the parameters of the model can be set with a small sample data set and the resulting model can make good predictions for a large dataset. We illustrate how to apply the approach with a concrete example.\",\n \"Title: Towards estimation error guarantees for distinct values\\nYear: 2000\\n\\nAbstract: We consider the problem of estimating the number of distinct values in a column of a table. For large tables without an index on the column, random sampling appears to be the only scalable approach for estimating the number of distinct values. We establish a powerful negative result stating that no estimator can guarantee small error across all input distributions, unless it examines a large fraction of the input data. In fact, any estimator must incur a significant error on at least some of a natural class of distributions. We then provide a new estimator which is provably optimal, in that its error is guaranteed to essentially match our negative result. A drawback of this estimator is that while its worst-case error is reasonable, it does not necessarily give the best possible error bound on any given distribution. Therefore, we develop heuristic estimators that are optimized for a class of typical input distributions. While these estimators lack strong guarantees on distribution-independent worst-case error, our extensive empirical comparison indicate their effectiveness both on real data sets and on synthetic data sets.\",\n \"Title: Algorithms for facility location problems with outliers\\nYear: 2001\\n\\nAbstract: Facility location problems are traditionally investigated with the assumption that all the clients are to be provided service. A significant shortcoming of this formulation is that a few very distant clients, called outliers, can exert a disproportionately strong influence over the final solution. In this paper we explore a generalization of various facility location problems (K-center, K-median, uncapacitated facility location etc) to the case when only a specified fraction of the customers are to be served. What makes the problems harder is that we have to also select the subset that should get service. We provide generalizations of various approximation algorithms to deal with this added constraint.\",\n \"Title: Dimension Reduction in the \\\\ell _1 Norm\\nYear: 2002\\n\\nAbstract: The Johnson-Lindenstrauss Lemma shows that any set of n points in Euclidean space can be mapped linearly down to O0({{(\\\\log n)} \\\\mathord{\\\\left/ {\\\\vphantom {{(\\\\log n)} {\\\\varepsilon ^2 }}} \\\\right. \\\\kern-\\\\nulldelimiterspace} {\\\\varepsilon ^2 }}) dimensions such that all pairwise distances are distorted by at most 1 + \\\\varepsilon. We study the following basic question: Does there exist an analogue of the Johnson-Lindenstrauss Lemma for the \\\\ell _1 norm?Note that Johnson-Lindenstrauss Lemma gives a linear embedding which is independent of the point set. For the \\\\ell _1 norm, we show that one cannot hope to use linear embeddingsas a dimensionality reduction tool for general point sets, even if the linear embedding is chosen as a function of the given point set. In particular, we construct a set of O(n) points in n\\\\ell _1^n such that any linear embedding into \\\\ell _1^d must incur a distortion of \\\\Omega (\\\\sqrt {{n \\\\mathord{\\\\left/ {\\\\vphantom {n d}} \\\\right. \\\\kern-\\\\nulldelimiterspace} d}}). This bound is tight up to a log n factor. We then initiate a systematic study of general classes of \\\\ell _1 embeddable metrics that admit low dimensional, small distortion embeddings. In particular, we show dimensionality reduction theorems for tree metrics, circular-decomposable metrics, and metrics supported on K2,3-free graphs, giving embeddings into \\\\ell _1 withconstant distortion. Finally, we also present lower bounds on dimension reduction techniques for other \\\\ell _p norms.Our work suggests that the notion of a stretch-limited embedding, where no distance is stretched by more than a factor d in any dimension, is important to the study of dimension reduction for \\\\ell _1. We use such stretch limited embeddings as a tool for proving lower bounds for dimension reduction and also as an algorithmic tool for proving positive results.\",\n \"Title: Algorithms for Capacitated Vehicle Routing\\nYear: 2001\\n\\nAbstract: Given n identical objects (pegs), placed at arbitrary initial locations, we consider the problem of transporting them efficiently to n target locations (slots) with a vehicle that can carry at most k pegs at a time. This problem is referred to as k-delivery TSP, and it is a generalization of the traveling salesman problem. We give a 5-approximation algorithm for the problem of minimizing the total distance traveled by the vehicle.There are two kinds of transportations possible---one that could drop pegs at intermediate locations and pick them up later in the route for delivery (preemptive) and one that transports pegs to their targets directly (nonpreemptive). In the former case, by exploiting the freedom to drop, one may be able to find a shorter delivery route. We construct a nonpreemptive tour that is within a factor 5 of the optimal preemptive tour. In addition we show that the ratio of the distances traveled by an optimal nonpreemptive tour versus a preemptive tour is bounded by 4.\",\n \"Title: On page migration and other relaxed task systems\\nYear: 2001\\n\\nAbstract: This paper is concerned with the page migration (or file migration) problem (Black and Sleator, Technical Report CMU-CS-89-201, Department of Computer Science, Carnegie-Mellon University, 1989) as part of a large class of on-line problems. The page migration problem deals with the management of pages residing in a network of processors. In the classical problem there is only one copy of each page which is accessed by different processors over time. The page is allowed to be migrated between processors. However a migration incurs higher communication cost than an access (proportionally to the page size). The problem is that of deciding when and where to migrate the page in order to lower access costs. A more general setting is the k-page migration problem where we wish to maintain k copies of the page. The page migration problems are concerned with a dilemma common to many on-line problems: determining when it is beneficial to make configuration changes. We deal with the relaxed task systems model which captures a large class of problems of this type, that can be described as the generalization of some original task system problem (Borodin et al., J. ACM 39(4) (1992) 745-763). Given a c-competitive algorithm for a task system we show how to obtain a deterministic O(c2) and randomized O(c) competitive algorithms for the corresponding relaxed task system. The result implies deterministic algorithms for k-page migration by using k-server (Manasse et al., J. Algorithms 11(2) (1990) 208-230) algorithms, and for network leasing by using generalized Steiner tree algorithms (Awerbuch et al., Proc 7th Ann. ACM-SIAM Symp. on Discrete Algorithms, January 1996, pp. 68-74), as well as providing solutions for natural generalizations of other problems (e.g. storage rearrangement (Fiat et al., Proc. 36th Ann. IEEE Symp. on Foundations of Computer Science, October 1995, pp. 392-403)). We further study some special cases of the k-page migration problem and get optimal deterministic algorithms. For the classical page migration problem we present a deterministic algorithm that achieves a competitive ratio of ~ 4:086, improving upon the previously best competitive ratio of 7 (Awerbuch et al., Proc. 25th ACM Symp. on Theory of Computing, May 1993, pp. 164-173). (The current lower bound on the problem is ~ 3:148 (Chrobak et al., J. Algorithms 24(1) (1997) 124-157). Copyright 2001 Elsevier Science B.V.\",\n \"Title: Query strategies for priced information\\nYear: 2002\\n\\nAbstract: We consider a class of problems in which an algorithm seeks to compute a function f over a set of n inputs, where each input has an associated price. The algorithm queries inputs sequentially, trying to learn the value of the function for the minimum cost. We apply the competitive analysis of algorithms to this framework, designing algorithms that incur large cost only when the cost of the cheapest \\\"proof\\\" for the value of f is also large. We provide algorithms that achieve the optimal competitive ratio for functions that include arbitrary Boolean AND/OR trees, and for the problem of searching in a sorted array. We also investigate a model for pricing in this framework and construct, for every AND/OR tree, a set of prices that satisfies a very strong type of equilibrium property.\",\n \"Title: Online multicast with egalitarian cost sharing\\nYear: 2008\\n\\nAbstract: We consider a multicast game played by a set of selfish noncooperative players (i.e., nodes) on a rooted undirected graph. Players arrive one by one and each connects to the root by greedily choosing a path minimizing its cost; the cost of using an edge is split equally among all users using the edge. How large can the sum of the players' costs be, compared to the cost of a \\\"socially optimal\\\" solution, defined to be a minimum Steiner tree connecting the players to the root? We show that the ratio is O(log2 n) and ©(log n), when there are n players. One can view this multicast game as a variant of Online Steiner Tree with a different cost sharing mechanism. Furthermore, we consider what happens if the players, in a second phase, are allowed to change their paths in order to decrease their costs. Thus, in the second phase players play best response dynamics until eventually a Nash equilibrium is reached. We show that the price of anarchy is O(log 3 n) and ©(log n). We also make progress towards understanding the challenging case where arrivals and path changes by existing terminals are interleaved. In particular, we analyze the interesting special case where the terminals fire in random order and prove that the cost of the solution produced (with arbitrary interleaving of actions) is at most O(polylog(n)√n) times the optimum.\",\n \"Title: Image similarity search with compact data structures\\nYear: 2004\\n\\nAbstract: The recent theoretical advances on compact data structures (also called \\\"sketches\\\") have raised the question of whether they can effectively be applied to content-based image retrieval systems. The main challenge is to derive an algorithm that achieves high-quality similarity searches while using compact metadata. This paper proposes a new similarity search method consisting of three parts. The first is a new region feature representation with weighted $=1 distance function, and EMD* match, an improved EMD match, to compute image similarity. The second is a thresholding and transformation algorithm to convert feature vectors into very compact data structures. The third is an EMD embedding based filtering method to speed up the query process. We have implemented a prototype system with the proposed method and performed experiments with a 10,000 image database. Our results show that the proposed method can achieve more effective similarity searches than previous approaches with metadata 3 to 72 times more compact than previous systems. The experiments also show that our EMD embedding based filtering technique can speed up the query process by a factor of 5 or more with little loss in query effectiveness.\",\n \"Title: A dependent LP-rounding approach for the k-median problem\\nYear: 2012\\n\\nAbstract: In this paper, we revisit the classical k-median problem. Using the standard LP relaxation for k-median, we give an efficient algorithm to construct a probability distribution on sets of k centers that matches the marginals specified by the optimal LP solution. Analyzing the approximation ratio of our algorithm presents significant technical difficulties: we are able to show an upper bound of 3.25. While this is worse than the current best known 3+ε guarantee of [2], because: (1) it leads to 3.25 approximation algorithms for some generalizations of the k-median problem, including the k-facility location problem introduced in [10], (2) our algorithm runs in $\\\\tilde{O}(k^3 n^2/\\\\delta^2)$ time to achieve 3.25(1+δ)-approximation compared to the O(n8) time required by the local search algorithm of [2] to guarantee a 3.25 approximation, and (3) our approach has the potential to beat the decade old bound of 3+ε for k-median. We also give a 34-approximation for the knapsack median problem, which greatly improves the approximation constant in [13]. Using the same technique, we also give a 9-approximation for matroid median problem introduced in [11], improving on their 16-approximation.\",\n \"Title: Improved Combinatorial Algorithms for Facility Location Problems\\nYear: 2005\\n\\nAbstract: We present improved combinatorial approximation algorithms for the uncapacitated facility location problem. Two central ideas in most of our results are cost scaling and greedy improvement. We present a simple greedy local search algorithm which achieves an approximation ratio of $2.414+\\\\epsilon$ in $\\\\tilde{O}(n^2/\\\\epsilon)$ time. This also yields a bicriteria approximation tradeoff of $(1+\\\\gamma,1+2/\\\\gamma)$ for facility cost versus service cost which is better than previously known tradeoffs and close to the best possible. Combining greedy improvement and cost scaling with a recent primal-dual algorithm for facility location due to Jain and Vazirani, we get an approximation ratio of $1.853$ in $\\\\tilde{O}(n^3)$ time. This is very close to the approximation guarantee of the best known algorithm which is linear programming (LP)-based. Further, combined with the best known LP-based algorithm for facility location, we get a very slight improvement in the approximation factor for facility location, achieving $1.728$. We also consider a variant of the capacitated facility location problem and present improved approximation algorithms for this.\",\n \"Title: Better streaming algorithms for clustering problems\\nYear: 2003\\n\\nAbstract: We study clustering problems in the streaming model, where the goal is to cluster a set of points by making one pass (or a few passes) over the data using a small amount of storage space. Our main result is a randomized algorithm for the k--Median problem which produces a constant factor approximation in one pass using storage space O(k poly log n). This is a significant improvement of the previous best algorithm which yielded a 2O(1/ε) approximation using O(nε) space. Next we give a streaming algorithm for the k--Median problem with an arbitrary distance function. We also study algorithms for clustering problems with outliers in the streaming model. Here, we give bicriterion guarantees, producing constant factor approximations by increasing the allowed fraction of outliers slightly.\",\n \"Title: Incremental Clustering and Dynamic Information Retrieval\\nYear: 2004\\n\\nAbstract: Motivated by applications such as document and image classification in information retrieval, we consider the problem of clustering dynamic point sets in a metric space. We propose a model called incremental clustering which is based on a careful analysis of the requirements of the information retrieval application, and which should also be useful in other applications. The goal is to efficiently maintain clusters of small diameter as new points are inserted. We analyze several natural greedy algorithms and demonstrate that they perform poorly. We propose new deterministic and randomized incremental clustering algorithms which have a provably good performance, and which we believe should also perform well in practice. We complement our positive results with lower bounds on the performance of incremental algorithms. Finally, we consider the dual clustering problem where the clusters are of fixed diameter, and the goal is to minimize the number of clusters.\",\n \"Title: A Derandomization Using Min-Wise Independent Permutations\\nYear: 1998\\n\\nAbstract: Min-wise independence is a recently introduced notion of limited independence, similar in spirit to pairwise independence. The later has proven essential for the derandomization of many algorithms. Here we show that approximate min-wise independence allows similar uses, by presenting a derandomization of the RNC algorithm for approximate set cover due to S. Rajagopalan and V. Vazirani. We also discuss how to derandomize their set multi-cover and multi-set multi-cover algorithms in restricted cases. The multi-cover case leads us to discuss the concept of k-minima-wise independence, a natural counterpart to k-wise independence.\",\n \"Title: Multireference alignment using semidefinite programming\\nYear: 2014\\n\\nAbstract: The multireference alignment problem consists of estimating a signal from multiple noisy shifted observations. Inspired by existing Unique-Games approximation algorithms, we provide a semidefinite program (SDP) based relaxation which approximates the maximum likelihood estimator (MLE) for the multireference alignment problem. Although we show this MLE problem is Unique-Games hard to approximate within any constant, we observe that our poly-time approximation algorithm for this problem appears to perform quite well in typical instances, outperforming existing methods. In an attempt to explain this behavior we provide stability guarantees for our SDP under a random noise model on the observations. This case is more challenging to analyze than traditional semi-random instances of Unique-Games: the noise model is on vertices of a graph and translates into dependent noise on the edges. Interestingly, we show that if certain positivity constraints in the relaxation are dropped, its solution becomes equivalent to performing phase correlation, a popular method used for pairwise alignment in imaging applications. Finally, we describe how symmetry reduction techniques from matrix representation theory can greatly decrease the computational cost of the SDP considered.\",\n \"Title: New Algorithms for Subset Query, Partial Match, Orthogonal Range Searching, and Related Problems\\nYear: 2002\\n\\nAbstract: We consider the subset query problem, defined as follows: given a set P of N subsets of a universe U, |U| = m, build a data structure, which for any query set Q 驴 U detects if there is any P 驴 P such that Q 驴 P. This is essentially equivalent to the partial match problem and is a fundamental problem in many areas. In this paper we present the first (to our knowledge) algorithms, which achieve non-trivial space and query time bounds for m = 驴(log N). In particular, we present two algorithms with the following tradeoffs: - N 驴 2O (mlog2 m 驴c/ log N) space, and O(N/2c) time, for any c - Nmc space and O(mN/c) query time, for any c 驴 N We extend these results to the more general problem of orthogonal range searching (both exact and approximate versions), approximate orthogonal range intersection and the exact and approximate versions of the nearest neighbor problem in l驴.\",\n \"Title: Near-optimal algorithms for maximum constraint satisfaction problems\\nYear: 2009\\n\\nAbstract: In this article, we present two approximation algorithms for the maximum constraint satisfaction problem with k variables in each constraint (MAX k-CSP). Given a (1 − ϵ) satisfiable 2CSP our first algorithm finds an assignment of variables satisfying a 1 − O(&sqrt;ϵ) fraction of all constraints. The best previously known result, due to Zwick, was 1 − O(ϵ1/3). The second algorithm finds a ck/2k approximation for the MAX k-CSP problem (where c 0.44 is an absolute constant). This result improves the previously best known algorithm by Hast, which had an approximation guarantee of Ω(k/(2k log k)). Both results are optimal assuming the unique games conjecture and are based on rounding natural semidefinite programming relaxations. We also believe that our algorithms and their analysis are simpler than those previously known.\",\n \"Title: Asymmetric distance estimation with sketches for similarity search in high-dimensional spaces\\nYear: 2008\\n\\nAbstract: Efficient similarity search in high-dimensional spaces is important to content-based retrieval systems. Recent studies have shown that sketches can effectively approximate L1 distance in high-dimensional spaces, and that filtering with sketches can speed up similarity search by an order of magnitude. It is a challenge to further reduce the size of sketches, which are already compact, without compromising accuracy of distance estimation. This paper presents an efficient sketch algorithm for similarity search with L2 distances and a novel asymmetric distance estimation technique. Our new asymmetric estimator takes advantage of the original feature vector of the query to boost the distance estimation accuracy. We also apply this asymmetric method to existing sketches for cosine similarity and L1 distance. Evaluations with datasets extracted from images and telephone records show that our L2 sketch outperforms existing methods, and the asymmetric estimators consistently improve the accuracy of different sketch methods. To achieve the same search quality, asymmetric estimators can reduce the sketch size by 10% to 40%.\",\n \"Title: Detecting High Log-Densities -- an O(n^1/4) Approximation for Densest k-Subgraph\\nYear: 2010\\n\\nAbstract: In the Densest k-Subgraph problem, given a graph G and a parameter k, one needs to find a subgraph of G induced on k vertices that contains the largest number of edges. There is a significant gap between the best known upper and lower bounds for this problem. It is NP-hard, and does not have a PTAS unless NP has subexponential time algorithms. On the other hand, the current best known algorithm of Feige, Kortsarz and Peleg [10], gives an approximation ratio of n(1/3-epsilon) for some fixed epsilon > 0 (later estimated at around epsilon = 1/90). We present an algorithm that for every epsilon > 0 approximates the Densest k-Subgraph problem within a ratio of n(1/4+epsilon) in time n(O(1/epsilon)). If allowed to run for time n(O(log n)), the algorithm achieves an approximation ratio of O(n(1/4)). Our algorithm is inspired by studying an average-case version of the problem where the goal is to distinguish random graphs from random graphs with planted dense subgraphs - the approximation, ratio we achieve for the general case matches the \\\"distinguishing ratio\\\" we obtain for this planted Problem. At a high level, our algorithms involve cleverly counting appropriately defined trees of constant size in G, and using these counts to identify the vertices of the dense subgraph. We say that a graph G(V, E) has log-density alpha if its average degree is Theta(vertical bar V vertical bar(alpha))in The algorithmic core of our result is a procedure to output a k-subgraph of 'nontrivial' density whenever the log-density of the densest k-subgraph is larger than the log-density of the host graph. We outline an extension to our approximation algorithm which achieves an O(n(1/4-epsilon))-approximation in O(2(nO(epsilon))) time. We also show that, for certain parameter ranges, eigenvalue and SDP based techniques can outperform our basic distinguishing algorithm for random instances (in polynomial time), though without improving upon the O(n(1/4)) guarantee overall. We outline an extension to our approximation algorithm which achieves an O(n(1/4-epsilon))-approximation in O(2(nO(epsilon))) time. We also show that, for certain parameter ranges, eigenvalue and SDP based techniques can outperform our basic distinguishing algorithm for random instances (in polynomial time), though without improving upon the O(n(1/4)) guarantee overall.\",\n \"Title: Modeling LSH for performance tuning\\nYear: 2008\\n\\nAbstract: Although Locality-Sensitive Hashing (LSH) is a promising approach to similarity search in high-dimensional spaces, it has not been considered practical partly because its search quality is sensitive to several parameters that are quite data dependent. Previous research on LSH, though obtained interesting asymptotic results, provides little guidance on how these parameters should be chosen, and tuning parameters for a given dataset remains a tedious process. To address this problem, we present a statistical performance model of Multi-probe LSH, a state-of-the-art variance of LSH. Our model can accurately predict the average search quality and latency given a small sample dataset. Apart from automatic parameter tuning with the performance model, we also use the model to devise an adaptive LSH search algorithm to determine the probing parameter dynamically for each query. The adaptive probing method addresses the problem that even though the average performance is tuned for optimal, the variance of the performance is extremely high. We experimented with three different datasets including audio, images and 3D shapes to evaluate our methods. The results show the accuracy of the proposed model: the recall errors predicted are within 5% from the real values for most cases; the adaptive search method reduces the standard deviation of recall by about 50% over the existing method.\",\n \"Title: On the advantage of network coding for improving network throughput\\nYear: 2004\\n\\nAbstract: Given a data network with link capacities, we consider the throughput of the network for a multicast session involving a source node and a given set of terminals. It is known that network coding can improve the throughput of the network. We study the coding advantage, i.e. the ratio of the throughput using network coding to that without using network coding. We show that the maximum coding advantage for a given network is equal to the integrality gap of certain linear programming (LP) formulations for a Steiner tree. This holds for both directed as well as undirected networks. For directed networks, the coding advantage is equal to the integrality gap of the directed Steiner tree LP formulation; for undirected networks, the coding advantage is equal to the integrality gap of the bidirected cut LP formulation for the Steiner tree. This relates the coding advantage to well studied notions in combinatorial optimization. Further, this connection improves the known bounds on the coding advantage for both undirected as well directed networks.\",\n \"Title: Clustering to minimize the sum of cluster diameters\\nYear: 2004\\n\\nAbstract: We study the problem of clustering points in a metric space so as to minimize the sum of cluster diameters or the sum of cluster radii. Significantly improving on previous results, we present a primal-dual based constant factor approximation algorithm for this problem. We present a simple greedy algorithm that achieves a logarithmic approximation. This also applies when the distance function is asymmetric and the objective is to minimize the sum of cluster radii. The previous best-known result obtained a logarithmic approximation with a constant factor blowup in the number of clusters. We also obtain an incremental clustering algorithm that maintains a solution whose cost is at most a constant factor times that of optimal with a constant factor blowup in the number of clusters.\",\n \"Title: Vertex Sparsifiers and Abstract Rounding Algorithms\\nYear: 2010\\n\\nAbstract: The notion of vertex sparsification (in particular cut-sparsification) is introduced in (Moitra, 2009), where it was shown that for any graph $G = (V, E)$ and any subset of $k$ terminals $K \\\\subset V$, there is a polynomial time algorithm to construct a graph $H = (K, E_H)$ \\\\emph{on just the terminal set} so that simultaneously for all cuts $(A, K-A)$, the value of the minimum cut in $G$ separating $A$ from $K -A$ is approximately the same as the value of the corresponding cut in $H$. Then approximation algorithms can be run directly on $H$ as a proxy for running on $G$. We give the first super-constant lower bounds for how well a cut-sparsifier $H$ can simultaneously approximate all minimum cuts in $G$. %In fact, we prove that in general we cannot hope for approximation factors better than We prove a lower bound of $\\\\Omega(\\\\log^{1/4} k)$ – this is polynomially-related to the known upper bound of $O(\\\\log k/\\\\log \\\\log k)$. Independently, a similar lower bound is given in (Makarychev, Makarychev, 2010). This is an exponential improvement on the $\\\\Omega(\\\\log \\\\log k)$ bound given in (Leighton, Moitra, 2010) which in fact was for a stronger vertex sparsification guarantee, and did not apply to cut sparsifiers. Despite this negative result, we show that for many natural optimization problems, we do not need to incur a multiplicative penalty for our reduction. Roughly, we show that any rounding algorithm which also works for the $0$-extension relaxation can be used to construct good vertex-sparsifiers for which the optimization problem is easy. Using this, we obtain optimal $O(\\\\log k)$-competitive Steiner oblivious routing schemes, which generalize the results in (Raecke, 2008). We also demonstrate that for a wide range of graph packing problems (which includes maximum concurrent flow, maximum multiflow and multicast routing, among others, as a special case), the integrality gap of the linear program is always at most $O(\\\\log k)$ times the integrality gap restricted to trees. Lastly, we use our ideas to give an efficient construction for vertex-sparsifiers that match the current best existential results – this was previously open. Our algorithm makes novel use of Earth-mover constraints.\",\n \"Title: Tight hardness results for minimizing discrepancy\\nYear: 2011\\n\\nAbstract: In the Discrepancy problem, we are given M sets {S1,..., SM} on N elements. Our goal is to find an assignment χ of {−1, + 1} values to elements, so as to minimize the maximum discrepancy maxj | ΣiεSj χ(i)|. Recently, Bansal gave an efficient algorithm for achieving O(√N) discrepancy for any set system where M = O(N) [Ban10], giving a constructive version of Spencer's proof that the discrepancy of any set system is at most O(√N) for this range of M [Spe85]. We show that from the perspective of computational efficiency, these results are tight for general set systems where M = O(N). Specifically, we show that it is NP-hard to distinguish between such set systems with discrepancy zero and those with discrepancy Ω(√N). This means that even if the optimal solution has discrepancy zero, we cannot hope to efficiently find a coloring with discrepancy o(√N). We also consider the hardness of the Discrepancy problem on sets with bounded shatter function, and show that the upper bounds due to Matoušek [Mat95] are tight for these sets systems as well. The hardness results in both settings are obtained from a common framework: we compose a family of high discrepancy set systems with set systems for which it is NP-hard to distinguish instances with discrepancy zero from instances in which a large number of the sets (i.e. constant fraction of the sets) have non-zero discrepancy. Our composition amplifies this zero versus non-zero gap.\",\n \"Title: On the impossibility of dimension reduction in l1\\nYear: 2003\\n\\nAbstract: The Johnson--Lindenstrauss lemma shows that any n points in Euclidean space (i.e., ℝn with distances measured under the ℓ2 norm) may be mapped down to O((log n)/ε2) dimensions such that no pairwise distance is distorted by more than a (1 + ε) factor. Determining whether such dimension reduction is possible in ℓ1 has been an intriguing open question. We show strong lower bounds for general dimension reduction in ℓ1. We give an explicit family of n points in ℓ1 such that any embedding with constant distortion D requires nΩ(1/D2) dimensions. This proves that there is no analog of the Johnson--Lindenstrauss lemma for ℓ1; in fact, embedding with any constant distortion requires nΩ(1) dimensions. Further, embedding the points into ℓ1 with (1+ε) distortion requires n½−O(ε log(1/ε)) dimensions. Our proof establishes this lower bound for shortest path metrics of series-parallel graphs. We make extensive use of linear programming and duality in devising our bounds. We expect that the tools and techniques we develop will be useful for future investigations of embeddings into ℓ1.\",\n \"Title: Smoothed analysis of tensor decompositions\\nYear: 2013\\n\\nAbstract: Low rank decomposition of tensors is a powerful tool for learning generative models. The uniqueness results that hold for tensors give them a significant advantage over matrices. However, tensors pose serious algorithmic challenges; in particular, much of the matrix algebra toolkit fails to generalize to tensors. Efficient decomposition in the overcomplete case (where rank exceeds dimension) is particularly challenging. We introduce a smoothed analysis model for studying these questions and develop an efficient algorithm for tensor decomposition in the highly overcomplete case (rank polynomial in the dimension). In this setting, we show that our algorithm is robust to inverse polynomial error -- a crucial property for applications in learning since we are only allowed a polynomial number of samples. While algorithms are known for exact tensor decomposition in some overcomplete settings, our main contribution is in analyzing their stability in the framework of smoothed analysis. Our main technical contribution is to show that tensor products of perturbed vectors are linearly independent in a robust sense (i.e. the associated matrix has singular values that are at least an inverse polynomial). This key result paves the way for applying tensor methods to learning problems in the smoothed setting. In particular, we use it to obtain results for learning multi-view models and mixtures of axis-aligned Gaussians where there are many more \\\\\\\"components\\\\\\\" than dimensions. The assumption here is that the model is not adversarially chosen, which we formalize by thinking of the model parameters as being perturbed. We believe this an appealing way to analyze realistic instances of learning problems, since this framework allows us to overcome many of the usual limitations of using tensor methods.\",\n \"Title: Sampling bounds for stochastic optimization\\nYear: 2005\\n\\nAbstract: A large class of stochastic optimization problems can be modeled as minimizing an objective function f that depends on a choice of a vector x ∈ X, as well as on a random external parameter ω∈ Ω given by a probability distribution π. The value of the objective function is a random variable and often the goal is to find an x ∈ X to minimize the expected cost Eω[fω(x)]. Each ω is referred to as a scenario. We consider the case when Ω is large or infinite and we are allowed to sample from π in a black-box fashion. A common method, known as the SAA method (sample average approximation), is to pick sufficiently many independent samples from π and use them to approximate π and correspondingly Eω[fω(x)]. This is one of several scenario reduction methods used in practice. There has been substantial recent interest in two-stage stochastic versions of combinatorial optimization problems which can be modeled by the framework described above. In particular, we are interested in the model where a parameter λ bounds the relative factor by which costs increase if decisions are delayed to the second stage. Although the SAA method has been widely analyzed, the known bounds on the number of samples required for a (1+ε) approximation depend on the variance of π even when λ is assumed to be a fixed constant. Shmoys and Swamy [13,14] proved that a polynomial number of samples suffice when f can be modeled as a linear or convex program. They used modifications to the ellipsoid method to prove this. In this paper we give a different proof, based on earlier methods of Kleywegt, Shapiro, Homem-De-Mello [6] and others, that a polynomial number of samples suffice for the SAA method. Our proof is not based on computational properties of f and hence also applies to integer programs. We further show that small variations of the SAA method suffice to obtain a bound on the sample size even when we have only an approximation algorithm to solve the sampled problem. We are thus able to extend a number of algorithms designed for the case when π is given explicitly to the case when π is given as a black-box sampling oracle.\",\n \"Title: Efficient filtering with sketches in the ferret toolkit\\nYear: 2006\\n\\nAbstract: Ferret is a toolkit for building content-based similarity search systems for feature-rich data types such as audio, video, and digital photos.The key component of this toolkit is a content-based similarity search engine for generic, multi-feature object representations. This paper describes the filtering mechanism used in the Ferret toolkit and experimental results with several datasets. The filtering mechanism uses approximation algorithms to generate a candidate set, and then ranks the objects in the candidate set with a more sophisticated multi-feature distance measure. The paper compared two filtering methods: using segment feature vectors and sketches constructed from segment feature vectors. Our experimental results show that filtering can substantially speedup the search process and reduce memory requirement while maintaining good search quality. To help systems designers choose the filtering parameters, we have developed a rank-based analytical model for the filtering algorithm using sketches. Our experiments show that the model gives conservative and good prediction for different datasets.\",\n \"Title: Approximating min-sum k-clustering in metric spaces\\nYear: 2001\\n\\nAbstract: The min-sum k-clustering problem in a metric space is to find a partition of the space into k clusters as to minimize the total sum of distances between pairs of points assigned to the same cluster. We give the first polynomial time non-trivial approximation algorithm for this problem. The algorithm provides an $\\\\ratio$ approximation to the min-sum k-clustering problem in general metric spaces, with running time $\\\\runtime$. The result is based on embedding of metric spaces into hierarchically separated trees. We also provide a bicriteria approximation result that provides a constant approximation factor solution with only a constant factor increase in the number of clusters. This result is obtained by modifying and drawing ideas from recently developed primal dual approximation algorithms for facility location.\",\n \"Title: On the Integrality Ratio for the Asymmetric Traveling Salesman Problem\\nYear: 2006\\n\\nAbstract: We improve the lower bound on the integrality ratio of the Held-Karp bound for asymmetric TSP with triangle inequality from 4/3 to 2.\",\n \"Title: Directed metrics and directed graph partitioning problems\\nYear: 2006\\n\\nAbstract: The theory of embeddings of finite metrics has provided a powerful toolkit for graph partitioning problems in undirected graphs. The connection comes from the fact that the integrality gaps of mathematical programming relaxations for sparsest cut in undirected graphs is exactly equal to the minimum distortion required to embed certain metrics into l1. No analog of this metric embedding theory exists for directed (asymmetric) metrics, the natural distance functions that arise in considering mathematical relaxations for directed graph partioning problems. We initiate a study of metric embeddings for directed metrics, motivated by understanding directed variants of sparsest cut.It turns out that there are two different ways to formulate sparsest cut in directed graphs (depending on whether one insists on partitioning the graph into two pieces or not). Different subclasses of directed metrics arise in the consideration of mathematical relaxations for these two formulations and the embedding questions that result are quite different. Unlike in the undirected case, where the natural host space is l1, the host space in the directed case is not obvious and depends on the problem formulation. Our work is a first step at understanding this space of directed metrics, the resulting embedding questions and their relationships to directed graph partitioning problems.\",\n \"Title: Beating the Random Ordering Is Hard: Every Ordering CSP Is Approximation Resistant\\nYear: 2011\\n\\nAbstract: We prove that, assuming the Unique Games conjecture (UGC), every problem in the class of ordering constraint satisfaction problems (OCSPs) where each constraint has constant arity is approximation resistant. In other words, we show that if $\\\\rho$ is the expected fraction of constraints satisfied by a random ordering, then obtaining a $\\\\rho'$ approximation for any $\\\\rho'\\\\rho$ is UG-hard. For the simplest OCSP, the Maximum Acyclic Subgraph (MAS) problem, this implies that obtaining a $\\\\rho$-approximation for any constant $\\\\rho1/2$ is UG-hard. Specifically, for every constant $\\\\varepsilon0$ the following holds: given a directed graph $G$ that has an acyclic subgraph consisting of a fraction $(1-\\\\varepsilon)$ of its edges, it is UG-hard to find one with more than $(1/2+\\\\varepsilon)$ of its edges. Note that it is trivial to find an acyclic subgraph with $1/2$ the edges by taking either the forward or backward edges in an arbitrary ordering of the vertices of $G$. The MAS problem has been well studied, and beating the random ordering for MAS has been a basic open problem. An OCSP of arity $k$ is specified by a subset $\\\\Pi\\\\subseteq S_k$ of permutations on $\\\\{1,2,\\\\dots,k\\\\}$. An instance of such an OCSP is a set $V$ and a collection of constraints, each of which is an ordered $k$-tuple of $V$. The objective is to find a global linear ordering of $V$ while maximizing the number of constraints ordered as in $\\\\Pi$. A random ordering of $V$ is expected to satisfy a $\\\\rho=\\\\frac{|\\\\Pi|}{k!}$ fraction. We show that, for any fixed $k$, it is hard to obtain a $\\\\rho'$-approximation for $\\\\Pi$-OCSP for any $\\\\rho'\\\\rho$. The result is in fact stronger: we show that for every $\\\\Lambda\\\\subseteq\\\\Pi\\\\subseteq S_k$, and an arbitrarily small $\\\\varepsilon$, it is hard to distinguish instances where a $(1-\\\\varepsilon)$ fraction of the constraints can be ordered according to $\\\\Lambda$ from instances where at most a $(\\\\rho+\\\\varepsilon)$ fraction can be ordered as in $\\\\Pi$. A special case of our result is that the Betweenness problem is hard to approximate beyond a factor $1/3$. The results naturally generalize to OCSPs which assign a payoff to the different permutations. Finally, our results imply (unconditionally) that a simple semidefinite relaxation for MAS does not suffice to obtain a better approximation.\",\n \"Title: Delayed information and action in on-line algorithms\\nYear: 1998\\n\\nAbstract: Most on-line analysis assumes that, at each time step, all relevant information up to that time step is available and a decision has an immediate effect. In many on-line problems, however, the time when relevant information is available and the time a decision has an effect may be decoupled. For example, when making an investment, one might not have completely up-to-date information on market prices. Similarly, a buy or sell order might only be executed some time in the future. We introduce and explore natural delayed models for several well-known on-line problems. Our analyses demonstrate the importance of considering timeliness in determining the competitive ratio of an on-line algorithm. For many problems, we demonstrate that there exist algorithms with small competitive ratios even when large delays affect the timeliness of information and the effect of decisions. Copyright 2001 Academic Press.\",\n \"Title: The Finite Capacity Dial-A-Ride Problem\\nYear: 1998\\n\\nAbstract: We give the first non-trivial approximation algorithm for the Capacitated Dial-a-Ride problem: given a collection of objects located at points in a metric space, a specified destination point for each object, and a vehicle with a capacity of at most k objects, the goal is to compute a shortest tour for the vehicle in which all objects can be delivered to their destinations while ensuring that the vehicle carries at most k objects at any point in time. The problem is known under several names, including the Stacker Crane problem and the Dial-a-Ride problem. No theoretical approximation guarantees were known for this problem other than for the cases k=1,\\\\infty and the trivial O(k) approximation for general capacity k. We give an algorithm with approximation ratio O(sqrt{k}) for special instances on a class of tree metrics called height-balanced trees. Using Bartal's recent results on the probabilistic approximation of metric spaces by tree metrics, we obtain an approximation ratio of O(sqrt{k} log n log log n)$ for arbitrary n point metric spaces. When the points lie on a line (line metric), we provide a 2-approximation algorithm.We also consider the Dial-a-Ride problem in another framework: when the vehicle is allowed to leave objects at intermediate locations and pick them up at a later time and deliver them. For this model, we design an approximation algorithm whose performance ratio is O(1) for tree metrics and O(log n log log n) for arbitrary metrics.We also study the ratio between the values of the optimal solutions for the two versions of the problem. We show that unlike in k-delivery TSP in which all the objects are identical, this ratio is not bounded by a constant for the Dial-a-Ride problem, and it could be as large as \\\\Omega(k^{2/3}).\",\n \"Title: Fitting Tree Metrics: Hierarchical Clustering and Phylogeny\\nYear: 2011\\n\\nAbstract: Given dissimilarity data on pairs of objects in a set, we study the problem of fitting a tree metric to this data so as to minimize additive error (i.e. some measure of the difference between the tree metric and the given data). This problem arises in constructing an M -level hierarchical clustering of objects (or an ultrametric on objects) so as to match the given dissimilarity data - a basic problem in statistics. Viewed in this way, the problem is a generalization of the correlation clustering problem (which corresponds to M = 1). We give a very simple randomized combinatorial algorithm for the M - level hierarchical clustering problem that achieves an approximation ratio of M +2. This is a generalization of a previous factor 3 algorithm for correlation clustering on complete graphs. The problem of fitting tree metrics also arises in phylogeny where the objective is to learn the evolution tree by fitting a tree to dissimilarity data on taxa. The quality of the fit is measured by taking the 'p norm of the difference between the tree metric con- structed and the given data. Previous results obtained a factor 3 approximation for finding the closest tree tree metric under the '1 norm. No non-trivial approxima- tion for general 'p norms was known before. We present a novel LP formulation for this problem and obtain an O((log n log log n) 1=p ) approximation using this. En route, we obtain an O((log n log log n) 1=p ) approxima- tion for the closest ultrametric under the 'p norm. Our techniques are based on representing and viewing an ul- trametric as a hierarchy of clusterings, and may be use- ful in other contexts.\",\n \"Title: Every Permutation CSP of arity 3 is Approximation Resistant\\nYear: 2009\\n\\nAbstract: A permutation constraint satisfaction problem (permCSP) of arity k is specified by a subset Lambda of permutations on $\\\\{1,2,\\\\dots,k\\\\}$. An instance of such a permCSP consists of a set of variables $V$ and a collection of constraints each of which is an ordered $k$-tuple of $V$. The objective is to find a global ordering $\\\\sigma$ of the variables that maximizes the number of constraint tuples whose ordering (under $\\\\sigma$) follows a permutation in $\\\\Lambda$. This is just the natural extension of constraint satisfaction problems over finite domains (such as Boolean CSPs) to the world of ordering problems. The simplest permCSP corresponds to the case when $\\\\Lambda$ consists of the identity permutation on two variables. This is just the Maximum Acyclic Subgraph (\\\\mas) problem. It was recently shown that the \\\\mas\\\\ problem is Unique-Games hard to approximate within a factor better than the trivial $1/2$ achieved by a random ordering [GMR08]. Building on this work, in this paper we show that for *every* permCSP of arity $3$, beating the random ordering is Unique-Games hard. The result is in fact stronger: we show that for every $\\\\Lambda \\\\subseteq \\\\Pi \\\\subseteq S_3$, given an instance of permCSP$(\\\\Lambda)$ that is almost-satisfiable, it is hard to find an ordering that satisfies more than $\\\\frac{|\\\\Pi|}{6} +\\\\eps$ of the constraints even under the relaxed constraint $\\\\Pi$ (for arbitrary $\\\\eps 0$). A special case of our result is that the *Betweenness* problem is hard to approximate beyond a factor $1/3$. Interestingly, for *satisfiable* instances of Betweenness, a factor $1/2$ approximation algorithm is known. Thus, every permutation CSP of arity up to $3$ resists approximation beyond the trivial random ordering threshold. In contrast, for Boolean CSPs, there are both approximation resistant and non-trivially approximable CSPs of arity $3$.\",\n \"Title: Limits of Approximation Algorithms: PCPs and Unique Games (DIMACS Tutorial Lecture Notes)\\nYear: 2010\\n\\nAbstract: These are the lecture notes for the DIMACS Tutorial \\\"Limits of Approximation\\nAlgorithms: PCPs and Unique Games\\\" held at the DIMACS Center, CoRE Building,\\nRutgers University on 20-21 July, 2009. This tutorial was jointly sponsored by\\nthe DIMACS Special Focus on Hardness of Approximation, the DIMACS Special Focus\\non Algorithmic Foundations of the Internet, and the Center for Computational\\nIntractability with support from the National Security Agency and the National\\nScience Foundation.\\n The speakers at the tutorial were Matthew Andrews, Sanjeev Arora, Moses\\nCharikar, Prahladh Harsha, Subhash Khot, Dana Moshkovitz and Lisa Zhang. The\\nsribes were Ashkan Aazami, Dev Desai, Igor Gorodezky, Geetha Jagannathan,\\nAlexander S. Kulikov, Darakhshan J. Mir, Alantha Newman, Aleksandar Nikolov,\\nDavid Pritchard and Gwen Spencer.\",\n \"Title: Greedy approximation algorithms for finding dense components in a graph\\nYear: 2000\\n\\nAbstract: We study the problem of finding highly connected subgraphs of undirected and directed graphs. For undirected graphs, the notion of density of a subgraph we use is the average degree of the subgraph. For directed graphs, a corresponding notion of density was introduced recently by Kannan and Vinay. This is designed to quantify highly connectedness of substructures in a sparse directed graph such as the web graph. We study the optimization problems of finding subgraphs maximizing these notions of density for undirected and directed graphs. This paper gives simple greedy approximation algorithms for these optimization problems. We also answer an open question about the complexity of the optimization problem for directed graphs.\",\n \"Title: Approximating the smallest grammar: Kolmogorov complexity in natural models\\nYear: 2002\\n\\nAbstract: We consider the problem of finding the smallest context-free grammar that generates exactly one given string of length n. The size of this grammar is of theoretical interest as an efficiently computable variant of Kolmogorov complexity. The problem is of practical importance in areas such as data compression and pattern extraction.The smallest grammar is known to be hard to approximate to within a constant factor, and an o(logn/log logn) approximation would require progress on a long-standing algebraic problem [10]. Previously, the best proved approximation ratio was O(n1/2) for the Bisection algorithm [8]. Our main result is an exponential improvement of this ratio; we give an O(log (n/g*)) approximation algorithm, where g* is the size of the smallest grammar.We then consider other computable variants of Kolomogorov complexity. In particular we give an O(log2 n) approximation for the smallest non-deterministic finite automaton with advice that produces a given string. We also apply our techniques to \\\"advice-grammars\\\" and \\\"edit-grammars\\\", two other natural models of string complexity.\",\n \"Title: Integrality gaps for Sherali-Adams relaxations\\nYear: 2009\\n\\nAbstract: We prove strong lower bounds on integrality gaps of Sherali-Adams relaxations for MAX CUT, Vertex Cover, Sparsest Cut and other problems. Our constructions show gaps for Sherali-Adams relaxations that survive nδ rounds of lift and project. For MAX CUT and Vertex Cover, these show that even nδ rounds of Sherali-Adams do not yield a better than 2-ε approximation. The main combinatorial challenge in constructing these gap examples is the construction of a fractional solution that is far from an integer solution, but yet admits consistent distributions of local solutions for all small subsets of variables. Satisfying this consistency requirement is one of the major hurdles to constructing Sherali-Adams gap examples. We present a modular recipe for achieving this, building on previous work on metrics with a local-global structure. We develop a conceptually simple geometric approach to constructing Sherali-Adams gap examples via constructions of consistent local SDP solutions. This geometric approach is surprisingly versatile. We construct Sherali-Adams gap examples for Unique Games based on our construction for MAX CUT together with a parallel repetition like procedure. This in turn allows us to obtain Sherali-Adams gap examples for any problem that has a Unique Games based hardness result (with some additional conditions on the reduction from Unique Games). Using this, we construct 2-ε gap examples for Maximum Acyclic Subgraph that rules out any family of linear constraints with support at most nδ.\",\n \"Title: Approximating a Finite Metric by a Small Number of Tree Metrics\\nYear: 1998\\n\\nAbstract: Bartal gave a randomized polynomial time algorithm that given any n point metric G, constructs a tree T such that the expected stretch (distortion) of any edge is at most O(log n log log n). His result has found several applications and in particular has resulted in approximation algorithms for many graph optimization problems. However approximation algorithms based on his result are inherently randomized. In this paper we derandomize the use of Bartal's algorithm in the design of approximation algorithms.We give an efficient polynomial time algorithm that given a finite n point metric G, constructs O(n log n) trees and a probability distribution \\\\mu on them such that the expected stretch of any edge of G in a tree chosen according to \\\\mu is at most O(log n log log n). Our result establishes that finite metrics can be probabilistically approximated by a small number of tree metrics. We obtain the first deterministic approximation algorithms for buy-at-bulk network design and vehicle routing; in addition we subsume results from our earlier work on derandomization. Our main result is obtained by a novel view of probabilistic approximation of metric spaces as a deterministic optimization problem via linear programming. This view also provides a new proof of Bartal's result that might be easier to generalize.We also show that graphs induced by points in \\\\Re^d_p (d-dimensional real normed space equipped with the l_p norm) can be O(f(d,p) log n)- -probabilistically approximated by tree metrics where f(d,p) = d^{1/p} for 1\",\n \"Title: Relax, No Need to Round: Integrality of Clustering Formulations\\nYear: 2014\\n\\nAbstract: We study exact recovery conditions for convex relaxations of point cloud clustering problems, focusing on two of the most common optimization problems for unsupervised clustering: k-means and k-median clustering. Motivations for focusing on convex relaxations are: (a) they come with a certificate of optimality, and (b) they are generic tools which are relatively parameter-free, not tailored to specific assumptions over the input. More precisely, we consider the distributional setting where there are k clusters in Rm and data from each cluster consists of n points sampled from a symmetric distribution within a ball of unit radius. We ask: what is the minimal separation distance between cluster centers needed for convex relaxations to exactly recover these k clusters as the optimal integral solution? For the k-median linear programming relaxation we show a tight bound: exact recovery is obtained given arbitrarily small pairwise separation ε > O between the balls. In other words, the pairwise center separation is δ > 2+ε. Under the same distributional model, the k-means LP relaxation fails to recover such clusters at separation as large as δ = 4. Yet, if we enforce PSD constraints on the k-means LP, we get exact cluster recovery at separation as low as δ > min{2 + √2k/m}, 2+√2 + 2/m} + ε. In contrast, common heuristics such as Lloyd's algorithm (a.k.a. the k means algorithm) can fail to recover clusters in this setting; even with arbitrarily large cluster separation, k-means++ with overseeding by any constant factor fails with high probability at exact cluster recovery. To complement the theoretical analysis, we provide an experimental study of the recovery guarantees for these various methods, and discuss several open problems which these experiments suggest.\",\n \"Title: Online Bipartite Matching with Decomposable Weights.\\nYear: 2014\\n\\nAbstract: We study a weighted online bipartite matching problem: G(V-1, V-2, E) is a weighted bipartite graph where V-1 is known beforehand and the vertices of V-2 arrive online. The goal is to match vertices of V-2 as they arrive to vertices in V-1, so as to maximize the sum of weights of edges in the matching. If assignments to V-1 cannot be changed, no bounded competitive ratio is achievable. We study the weighted online matching problem with free disposal, where vertices in V-1 can be assigned multiple times, but only get credit for the maximum weight edge assigned to them over the course of the algorithm. For this problem, the greedy algorithm is 0.5-competitive and determining whether a better competitive ratio is achievable is a well known open problem. We identify an interesting special case where the edge weights are decomposable as the product of two factors, one corresponding to each end point of the edge. This is analogous to the well studied related machines model in the scheduling literature, although the objective functions are different. For this case of decomposable edge weights, we design a 0.5664 competitive randomized algorithm in complete bipartite graphs. We show that such instances with decomposable weights are non-trivial by establishing upper bounds of 0.618 for deterministic and 0.8 for randomized algorithms. A tight competitive ratio of 1 - 1/e approximate to 0.632 was known previously for both the 0-1 case as well as the case where edge weights depend on the offline vertices only, but for these cases, reassignments cannot change the quality of the solution. Beating 0.5 for weighted matching where reassignments are necessary has been a significant challenge. We thus give the first online algorithm with competitive ratio strictly better than 0.5 for a non-trivial case of weighted matching with free disposal.\",\n \"Title: Resource optimization in QoS multicast routing of real-time multimedia\\nYear: 2004\\n\\nAbstract: We consider a network design problem, where applications require various levels of Quality-of-Service (QoS) while connections have limited performance. Suppose that a source needs to send a message to a heterogeneous set of receivers. The objective is to design a low-cost multicast tree from the source that would provide the QoS levels (e.g., bandwidth) requested by the receivers. We assume that the QoS level required on a link is the maximum among the QoS levels of the receivers that are connected to the source through the link. In accordance, we define the cost of a link to be a function of the QoS level that it provides. This definition of cost makes this optimization problem more general than the classical Steiner tree problem. We consider several variants of this problem all of which are proved to be NP-Hard. For the variant where QoS levels of a link can vary arbitrarily and the cost function is linear in its QoS level, we give a heuristic that achieves a multicast tree with cost at most a constant times the cost of an optimal multicast tree. The constant depends on the best constant approximation ratio of the classical Steiner tree problem. For the more general variant, where each link has a given QoS level and cost we present a heuristic that generates a multicast tree with cost O(min {log r, k}) times the cost of an optimal tree, where r denotes the number of receivers, and k denotes the number of different levels of QoS required. We generalize this result to hold for the case of many multicast groups.\",\n \"Title: Maximizing quadratic programs: extending Grothendieck's inequality\\nYear: 2004\\n\\nAbstract: This paper considers the following type of quadratic programming problem. Given an arbitrary matrix A, whose diagonal elements are zero, find x 驴 {-1, 1}^n such that x^TAx is maximized. Our approximation algorithm for this problem uses the canonical semidefinite relaxation and returns a solution whose ratio to the optimum is in 驴(1/log n). This quadratic programming problem can be seen as an extension to that of maximizing x^TAy (where y's components are also 卤1). Grothendieck's inequality states that the ratio of the optimum value of the latter problem to the optimum of its canonical semidefinite relaxation is bounded below by a constant. The study of this type of quadratic program arose from a desire to approximate the maximum correlation in correlation clustering. Nothing substantive was known about this problem; we present an 驴(1/log n) approximation, based on our quadratic programming algorithm. We can also guarantee that our quadratic programming algorithm returns a solution to the MAXCUT problem that has a significant advantage over a random assignment.\",\n \"Title: Minimum outage transmission over fading channels with delay constraint\\nYear: 2000\\n\\nAbstract: We consider a block flat fading channel, where both the transmitter and receiver have perfect knowledge of the channel gain of the current block, but have no knowledge of future blocks. For a delay constraint of K blocks, and a target rate R0, we derive the optimum power adaptation strategy that would minimize the probability of outage, which is equivalent to finding the outage capacity. Both, short term and long term power constraints are considered. Significant power gains are afforded by the strategy for all SNRs, even for small K\",\n \"Title: The Hardness of Approximation of Euclidean k-means.\\nYear: 2015\\n\\nAbstract: The Euclidean $k$-means problem is a classical problem that has been extensively studied in the theoretical computer science, machine learning and the computational geometry communities. In this problem, we are given a set of $n$ points in Euclidean space $R^d$, and the goal is to choose $k$ centers in $R^d$ so that the sum of squared distances of each point to its nearest center is minimized. The best approximation algorithms for this problem include a polynomial time constant factor approximation for general $k$ and a $(1+\\\\epsilon)$-approximation which runs in time $poly(n) 2^{O(k/\\\\epsilon)}$. At the other extreme, the only known computational complexity result for this problem is NP-hardness [ADHP'09]. The main difficulty in obtaining hardness results stems from the Euclidean nature of the problem, and the fact that any point in $R^d$ can be a potential center. This gap in understanding left open the intriguing possibility that the problem might admit a PTAS for all $k,d$. In this paper we provide the first hardness of approximation for the Euclidean $k$-means problem. Concretely, we show that there exists a constant $\\\\epsilon > 0$ such that it is NP-hard to approximate the $k$-means objective to within a factor of $(1+\\\\epsilon)$. We show this via an efficient reduction from the vertex cover problem on triangle-free graphs: given a triangle-free graph, the goal is to choose the fewest number of vertices which are incident on all the edges. Additionally, we give a proof that the current best hardness results for vertex cover can be carried over to triangle-free graphs. To show this we transform $G$, a known hard vertex cover instance, by taking a graph product with a suitably chosen graph $H$, and showing that the size of the (normalized) maximum independent set is almost exactly preserved in the product graph using a spectral analysis, which might be of independent interest.\",\n \"Title: Label optimal regret bounds for online local learning.\\nYear: 2015\\n\\nAbstract: We resolve an open question from (Christiano, 2014b) posed in COLT'14 regarding the optimal dependency of the regret achievable for online local learning on the size of the label set. In this framework the algorithm is shown a pair of items at each step, chosen from a set of $n$ items. The learner then predicts a label for each item, from a label set of size $L$ and receives a real valued payoff. This is a natural framework which captures many interesting scenarios such as collaborative filtering, online gambling, and online max cut among others. (Christiano, 2014a) designed an efficient online learning algorithm for this problem achieving a regret of $O(\\\\sqrt{nL^3T})$, where $T$ is the number of rounds. Information theoretically, one can achieve a regret of $O(\\\\sqrt{n \\\\log L T})$. One of the main open questions left in this framework concerns closing the above gap. In this work, we provide a complete answer to the question above via two main results. We show, via a tighter analysis, that the semi-definite programming based algorithm of (Christiano, 2014a), in fact achieves a regret of $O(\\\\sqrt{nLT})$. Second, we show a matching computational lower bound. Namely, we show that a polynomial time algorithm for online local learning with lower regret would imply a polynomial time algorithm for the planted clique problem which is widely believed to be hard. We prove a similar hardness result under a related conjecture concerning planted dense subgraphs that we put forth. Unlike planted clique, the planted dense subgraph problem does not have any known quasi-polynomial time algorithms. Computational lower bounds for online learning are relatively rare, and we hope that the ideas developed in this work will lead to lower bounds for other online learning scenarios as well.\",\n \"Title: Spectral Embedding Of K-Cliques, Graph Partitioning And K-Means\\nYear: 2016\\n\\nAbstract: We introduce and study a new notion of graph partitioning, intimately connected to spectral clustering and k-means clustering. Formally, given a graph G on n vertices, we ask to find a graph H that is the union of k cliques on n vertices, such that LG >=lambda L-H where ? is maximized. Here L-G and L-H are the (normalized) Laplacians of the graphs G and H respectively. Informally, our graph partitioning objective asks for the optimal spectral simplification of a given graph as a disjoint union of k cliques.We justify this objective function in several ways. First and foremost, we show that a commonly used spectral clustering algorithm implicitly optimizes this objective function, up to a factor of O(k). Using this connection, we immediately get an O(k)-approximation algorithm to our new objective function by simply using the spectral clustering algorithm on G. Next, we demonstrate another application of our objective function: we use it as a means to proving that simple spectral clustering algorithms can solve some well-studied graph partitioning problems (such as partitioning into expanders). Additionally, we also show that (a relaxation of) this optimization problem naturally arises as the dual problem to the question of finding the worst-case integrality gap instance for the classical k-means SDP. Finally, owing to these close connection between some classical clustering techniques (such as k-means and spectral clustering), we argue that a more complete understanding of this optimization problem could lead to new algorithmic insights and techniques for the area of graph partitioning.\",\n \"Title: On Approximating Target Set Selection.\\nYear: 2016\\n\\nAbstract: We study the Target Set Selection (TSS) problem introduced by Kempe, Kleinberg, and Tardos (2003). This problem models the propagation of influence in a network, in a sequence of rounds. A set of nodes is made active initially. In each subsequent round, a vertex is activated if at least a certain number of its neighbors are (already) active. In the minimization version, the goal is to activate a small set of vertices initially - a seed, or target, set - so that activation spreads to the entire graph. In the absence of a sublinear-factor algorithm for the general version, we provide a (sublinear) approximation algorithm for the bounded-round version, where the goal is to activate all the vertices in r rounds. Assuming a known conjecture on the hardness of Planted Dense Subgraph, we establish hardness-of-approximation results for the bounded-round version. We show that they translate to general Target Set Selection, leading to a hardness factor of n^(1/2-epsilon) for all epsilon u003e 0. This is the first polynomial hardness result for Target Set Selection, and the strongest conditional result known for a large class of monotone satisfiability problems. In the maximization version of TSS, the goal is to pick a target set of size k so as to maximize the number of nodes eventually active. We show an n^(1-epsilon) hardness result for the undirected maximization version of the problem, thus establishing that the undirected case is as hard as the directed case. Finally, we demonstrate an SETH lower bound for the exact computation of the optimal seed set.\",\n \"Title: Learning from Untrusted Data.\\nYear: 2017\\n\\nAbstract: The vast majority of theoretical results in machine learning and statistics assume that the training data is a reliable reflection of the phenomena to be learned. Similarly, most learning techniques used in practice are brittle to the presence of large amounts of biased or malicious data. Motivated by this, we consider two frameworks for studying estimation, learning, and optimization in the presence of significant fractions of arbitrary data. The first framework, list-decodable learning, asks whether it is possible to return a list of answers such that at least one is accurate. For example, given a dataset of n points for which an unknown subset of α n points are drawn from a distribution of interest, and no assumptions are made about the remaining (1âα)n points, is it possible to return a list of poly(1/α) answers? The second framework, which we term the semi-verified model, asks whether a small dataset of trusted data (drawn from the distribution in question) can be used to extract accurate information from a much larger but untrusted dataset (of which only an α-fraction is drawn from the distribution). We show strong positive results in both settings, and provide an algorithm for robust learning in a very general stochastic optimization setting. This result has immediate implications for robustly estimating the mean of distributions with bounded second moments, robustly learning mixtures of such distributions, and robustly finding planted partitions in random graphs in which significant portions of the graph have been perturbed by an adversary.\",\n \"Title: Approximate Hierarchical Clustering via Sparsest Cut and Spreading Metrics.\\nYear: 2016\\n\\nAbstract: Dasgupta recently introduced a cost function for the hierarchical clustering of a set of points given pairwise similarities between them. He showed that this function is NP-hard to optimize, but a top-down recursive partitioning heuristic based on an αn-approximation algorithm for uniform sparsest cut gives an approximation of O(αn log n) (the current best algorithm has [EQUATION]. We show that the aforementioned sparsest cut heuristic in fact obtains an O(αn)-approximation. The algorithm also applies to a generalized cost function studied by Dasgupta. Moreover, we obtain a strong inapproximability result, showing that the Hierarchical Clustering objective is hard to approximate to within any constant factor assuming the Small-Set Expansion (SSE) Hypothesis. Finally, we discuss approximation algorithms based on convex relaxations. We present a spreading metric SDP relaxation for the problem and show that it has integrality gap at most [EQUATION]. The advantage of the SDP relative to the sparsest cut heuristic is that it provides an explicit lower bound on the optimal solution and could potentially yield an even better approximation for hierarchical clustering. In fact our analysis of this SDP served as the inspiration for our improved analysis of the sparsest cut heuristic. We also show that a spreading metric LP relaxation gives an O(log n)-approximation.\",\n \"Title: Local Guarantees In Graph Cuts And Clustering\\nYear: 2017\\n\\nAbstract: Correlation Clustering is an elegant model that captures fundamental graph cut problems such as Min s - t Cut, Multiway Cut, and Multicut, extensively studied in combinatorial optimization. Here, we are given a graph with edges labeled + or - and the goal is to produce a clustering that agrees with the labels as much as possible: + edges within clusters and - edges across clusters. The classical approach towards Correlation Clustering (and other graph cut problems) is to optimize a global objective. We depart from this and study local objectives: minimizing the maximum number of disagreements for edges incident on a single node, and the analogous max min agreements objective. This naturally gives rise to a family of basic min-max graph cut problems. A prototypical representative is Min Max s-t Cut: find an s-t cut minimizing the largest number of cut edges incident on any node. We present the following results: (1) an O(root n)-approximation for the problem of minimizing the maximum total weight of disagreement edges incident on any node (thus providing the first known approximation for the above family of min-max graph cut problems), (2) a remarkably simple 7-approximation for minimizing local disagreements in complete graphs (improving upon the previous best known approximation of 48), and (3) a 1/(2+epsilon)-approximation for maximizing the minimum total weight of agreement edges incident on any node, hence improving upon the 1/(4+epsilon)-approximation that follows from the study of approximate pure Nash equilibria in cut and party affiliation games.\",\n \"Title: Resilience: A Criterion for Learning in the Presence of Arbitrary Outliers.\\nYear: 2018\\n\\nAbstract: We introduce a criterion, resilience, which allows properties of a dataset (such as its mean or best low rank approximation) to be robustly computed, even in the presence of a large fraction of arbitrary additional data. Resilience is a weaker condition than most other properties considered so far in the literature, and yet enables robust estimation in a broader variety of settings. We provide new information-theoretic results on robust distribution learning, robust estimation of stochastic block models, and robust mean estimation under bounded kth moments. We also provide new algorithmic results on robust distribution learning, as well as robust mean estimation in p-norms. Among our proof techniques is a method for pruning a high-dimensional distribution with bounded 1st moments to a stable core with bounded 2nd moments, which may be of independent interest.\",\n \"Title: Intelligent probing for locality sensitive hashing: multi-probe LSH and beyond\\nYear: 2017\\n\\nAbstract: AbstractThe past decade has been marked by the (continued) explosion of diverse data content and the fast development of intelligent data analytics techniques. One problem we identified in the mid-2000s was similarity search of feature-rich data. The challenge here was achieving both high accuracy and high efficiency in high-dimensional spaces. Locality sensitive hashing (LSH), which uses certain random space partitions and hash table lookups to find approximate nearest neighbors, was a promising approach with theoretical guarantees. But LSH alone was insufficient since a large number of hash tables were required to achieve good search quality. Building on an idea of Panigrahy, our multi-probe LSH method introduced the idea of intelligent probing. Given a query object, we strategically probe its neighboring hash buckets (in a query-dependent fashion) by calculating the statistical probabilities of similar objects falling into each bucket. Such intelligent probing can significantly reduce the number of hash tables while achieving high quality. In this paper, we revisit the problem motivation, the challenges, the key design considerations of multi-probe LSH, as well as discuss recent developments in this space and some questions for further research.\",\n \"Title: Min-Cost Bipartite Perfect Matching with Delays.\\nYear: 2017\\n\\nAbstract: In the min-cost bipartite perfect matching with delays (MBPMD) problem, requests arrive online at points of a finite metric space. Each request is either positive or negative and has to be matched to a request of opposite polarity. As opposed to traditional online matching problems, the algorithm does not have to serve requests as they arrive, and may choose to match them later at a cost. Our objective is to minimize the sum of the distances between matched pairs of requests (the connection cost) and the sum of the waiting times of the requests (the delay cost). This objective exhibits a natural tradeoff between minimizing the distances and the cost of waiting for better matches. This tradeoff appears in many real-life scenarios, notably, ride-sharing platforms. MBPMD is related to its non-bipartite variant, min-cost perfect matching with delays (MPMD), in which each request can be matched to any other request. MPMD was introduced by Emek et al. (STOCu002716), who showed an O(log^2(n)+log(Delta))-competitive randomized algorithm on n-point metric spaces with aspect ratio Delta.Our contribution is threefold. First, we present a new lower bound construction for MPMD and MBPMD. We get a lower bound of Omega(sqrt(log(n)/log(log(n)))) on the competitive ratio of any randomized algorithm for MBPMD. For MPMD, we improve the lower bound from Omega(sqrt(log(n))) (shown by Azar et al., SODAu002717) to Omega(log(n)/log(log(n))), thus, almost matching their upper bound of O(log(n)). Second, we adapt the algorithm of Emek et al. to the bipartite case, and provide a simplified analysis that improves the competitive ratio to O(log(n)). The key ingredient of the algorithm is an O(h)-competitive randomized algorithm for MBPMD on weighted trees of height h. Third, we provide an O(h)-competitive deterministic algorithm for MBPMD on weighted trees of height h. This algorithm is obtained by adapting the algorithm for MPMD by Azar et al. to the apparently more complicated bipartite setting.\",\n \"Title: Hashing-Based-Estimators for Kernel Density in High Dimensions\\nYear: 2018\\n\\nAbstract: Given a set of points P ⊂ ℝ\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">d</sup>\\n and a kernel k, the Kernel Density Estimate at a point x ∈ ℝ\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">d</sup>\\n is defined as KDE\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">P</sub>\\n (x) = 1/|P| Σy\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">∈P</sub>\\n k(x, y). We study the problem of designing a data structure that given a data set P and a kernel function, returns approximations to the kernel density of a query point in sublinear time. We introduce a class of unbiased estimators for kernel density implemented through locality-sensitive hashing, and give general theorems bounding the variance of such estimators. These estimators give rise to efficient data structures for estimating the kernel density in high dimensions for a variety of commonly used kernels. Our work is the first to provide data-structures with theoretical guarantees that improve upon simple random sampling in high dimensions.\",\n \"Title: Fully Dynamic Almost-Maximal Matching: Breaking the Polynomial Barrier for Worst-Case Time Bounds.\\nYear: 2017\\n\\nAbstract: Despite significant research efforts, the state-of-the-art algorithm for maintaining an approximate matching in fully dynamic graphs has a polynomial emph{worst-case} update time, even for very poor approximation guarantees. a recent breakthrough, Bhattacharya, Henzinger and Nanongkai showed how to maintain a constant approximation to the minimum vertex cover, and thus also a constant-factor estimate of the maximum matching size, with polylogarithmic worst-case update time. Later (in SODAu002717 Proc.) they improved the approximation factor all the way to $2+eps$. Nevertheless, the longstanding fundamental problem of emph{maintaining} an approximate matching with sub-polynomial worst-case time bounds remained open. In this work we present a randomized algorithm for maintaining an emph{almost-maximal} matching in fully dynamic graphs with polylogarithmic worst-case update time. Such a matching provides $(2+eps)$-approximations for both the maximum matching and the minimum vertex cover, for any $eps u003e 0$. Our result was done independently of the SODAu002717 $(2+eps)$-approximation result of Bhattacharya et al., so it provides the first $(2+eps)$-approximation for minimum vertex cover (together with Bhattacharya et al.u0027s result) and the first $(2+eps)$-approximation for maximum (integral) matching. The worst-case update time of our algorithm, namely $O(poly(log n,eps^{-1}))$, holds deterministically, while the almost-maximality guarantee holds with high probability. Moreover, this guarantee also bounds the number of changes (replacements) to our matching in the worst-case. This result not only settles the aforementioned problem on dynamic matchings, but also provides essentially the best possible (under the unique games conjecture) approximation guarantee for dynamic vertex cover.\",\n \"Title: On Finding Dense Common Subgraphs.\\nYear: 2018\\n\\nAbstract: We study the recently introduced problem of finding dense common subgraphs: Given a sequence of graphs that share the same vertex set, the goal is to find a subset of vertices $S$ that maximizes some aggregate measure of the density of the subgraphs induced by $S$ in each of the given graphs. Different choices for the aggregation function give rise to variants of the problem that were studied recently. We settle many of the questions left open by previous works, showing NP-hardness, hardness of approximation, non-trivial approximation algorithms, and an integrality gap for a natural relaxation.\",\n \"Title: On Estimating Edit Distance: Alignment, Dimension Reduction, and Embeddings.\\nYear: 2018\\n\\nAbstract: Edit distance is a fundamental measure of distance between strings and has been widely studied in computer science. While the problem of estimating edit distance has been studied extensively, the equally important question of actually producing an alignment (i.e., the sequence of edits) has received far less attention. Somewhat surprisingly, we show that any algorithm to estimate edit distance can be used in a black-box fashion to produce an approximate alignment of strings, with modest loss in approximation factor and small loss in run time. Plugging in the result of Andoni, Krauthgamer, and Onak, we obtain an alignment that is a $(log n)^{O(1/varepsilon^2)}$ approximation in time $tilde{O}(n^{1 + varepsilon})$. Closely related to the study of approximation algorithms is the study of metric embeddings for edit distance. We show that min-hash techniques can be useful in designing edit distance embeddings through three results: (1) An embedding from Ulam distance (edit distance over permutations) to Hamming space that matches the best known distortion of $O(log n)$ and also implicitly encodes a sequence of edits between the strings; (2) In the case where the edit distance between the input strings is known to have an upper bound $K$, we show that embeddings of edit distance into Hamming space with distortion $f(n)$ can be modified in a black-box fashion to give distortion $O(f(operatorname{poly}(K)))$ for a class of periodic-free strings; (3) A randomized dimension-reduction map with contraction $c$ and asymptotically optimal expected distortion $O(c)$, improving on the previous $tilde{O}(c^{1 + 2 / log log log n})$ distortion result of Batu, Ergun, and Sahinalp.\",\n \"Title: Hierarchical Clustering with Structural Constraints.\\nYear: 2018\\n\\nAbstract: Hierarchical clustering is a popular unsupervised data analysis method. For many real-world applications, we would like to exploit prior information about the data that imposes constraints on the clustering hierarchy, and is not captured by the set of features available to the algorithm. This gives rise to the problem of clustering with structural constraints. Structural constraints pose major challenges for bottom-up approaches like average/single linkage and even though they can be naturally incorporated into top-down divisive algorithms, no formal guarantees exist on the quality of their output. In this paper, we provide provable approximation guarantees for two simple top-down algorithms, using a recently introduced optimization viewpoint of hierarchical clustering with pairwise similarity information [Dasgupta, 2016]. We show how to find good solutions even in the presence of conflicting prior information, by formulating a constraint-based regularization of the objective. We further explore a variation of this objective for dissimilarity information [Cohen-Addad et al., 2018] and improve upon current techniques. Finally, we demonstrate our approach on a real dataset for the taxonomy application.\",\n \"Title: Local Density Estimation in High Dimensions.\\nYear: 2018\\n\\nAbstract: An important question that arises in the study of high dimensional vector representations learned from data is: given a set $mathcal{D}$ of vectors and a query $q$, estimate the number of points within a specified distance threshold of $q$. We develop two estimators, LSH Count and Multi-Probe Count that use locality sensitive hashing to preprocess the data to accurately and efficiently estimate the answers to such questions via importance sampling. A key innovation is the ability to maintain a small number of hash tables via preprocessing data structures and algorithms that sample from multiple buckets in each hash table. We give bounds on the space requirements and sample complexity of our schemes, and demonstrate their effectiveness in experiments on a standard word embedding dataset.\",\n \"Title: Hierarchical Clustering better than Average-Linkage.\\nYear: 2019\\n\\nAbstract: Hierarchical Clustering (HC) is a widely studied problem in exploratory data analysis, usually tackled by simple agglomerative procedures like average-linkage, single-linkage or complete-linkage. In this paper we focus on two objectives, introduced recently to give insight into the performance of average-linkage clustering: a similarity based HC objective proposed by [21] and a dissimilarity based HC objective proposed by [9]. In both cases, we present tight counterexamples showing that average-linkage cannot obtain better than 1/3 and 2/3 approximations respectively (in the worst-case), settling an open question raised in [21]. This matches the approximation ratio of a random solution, raising a natural question: can we beat average-linkage for these objectives? We answer this in the affirmative, giving two new algorithms based on semidefinite programming with provably better guarantees.\",\n \"Title: A sampling framework for counting temporal motifs.\\nYear: 2018\\n\\nAbstract: Pattern counting in graphs is fundamental to network science tasks, and there are many scalable methods for approximating counts of small patterns, often called motifs, in large graphs. However, modern graph datasets now contain richer structure, and incorporating temporal information in particular has become a critical part of network analysis. Temporal motifs, which are generalizations of small subgraph patterns that incorporate temporal ordering on edges, are an emerging part of the network analysis toolbox. However, there are no algorithms for fast estimation of temporal motifs counts; moreover, we show that even counting simple temporal star motifs is NP-complete. Thus, there is a need for fast and approximate algorithms. Here, we present the first frequency estimation algorithms for counting temporal motifs. More specifically, we develop a sampling framework that sits as a layer on top of existing exact counting algorithms and enables fast and accurate memory-efficient estimates of temporal motif counts. Our results show that we can achieve one to two orders of magnitude speedups with minimal and controllable loss in accuracy on a number of datasets.\",\n \"Title: Recovery Guarantees for Quadratic Tensors with Limited Observations.\\nYear: 2018\\n\\nAbstract: We consider the tensor completion problem of predicting the missing entries of a tensor. The commonly used CP model has a triple product form, but an alternate family of quadratic models which are the sum of pairwise products instead of a triple product have emerged from applications such as recommendation systems. Non-convex methods are the method of choice for learning quadratic models, and this work examines their sample complexity and error guarantee. Our main result is that with the number of samples being only linear in the dimension, all local minima of the mean squared error objective are global minima and recover the original tensor. We substantiate our theoretical results with experiments on synthetic and real-world data.\",\n \"Title: Efficient Density Evaluation for Smooth Kernels\\nYear: 2018\\n\\nAbstract: Given a kernel function k(.,.) and a dataset P⊂ R^d, the kernel density function of P at a point x∈ R\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">d</sup>\\n is equal to KDF\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">P</sub>\\n(x):= 1/|P| Σy∈P k(x, y). Kernel density evaluation has numerous applications, in scientific computing, statistics, computer vision, machine learning and other fields. In all of them it is necessary to evaluate KDF\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">P(x)</sub>\\n quickly, often for many inputs x and large point-sets P. In this paper we present a collection of algorithms for efficient KDF evaluation under the assumptions that the kernel k is \\\"smooth\\\", i.e. the value changes at most polynomially with the distance. This assumption is satisfied by several well-studied kernels, including the (generalized) t-student kernel and rational quadratic kernel. For smooth kernels, we give a data structure that, after O(dn log (Φ n)/ε^2) preprocessing, estimates KDF\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">P(x)</sub>\\n up to a factor of 1 ± ε in O(dlog (Φ n)/ε\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sup>\\n) time, where Phi; is the aspect ratio. The log(Φn) term can be further replaced by log n under an additional decay condition on k, which is satisfied by the aforementioned examples. We further extend the results in two ways. First, we use low-distortion embeddings to extend the results to kernels defined for spaces other than ℓ_2. The key feature of this reduction is that the distortion of the embedding affects only the running time of the algorithm, not the accuracy of the estimation. As a result, we obtain (1+ε)-approximate estimation algorithms for kernels over other ℓ\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">p</sub>\\n norms, Earth-Mover Distance, and other metric spaces. Second, for smooth kernels that are decreasing with distance, we present a general reduction from density estimation to approximate near neighbor in the underlying space. This allows us to construct algorithms for general doubling metrics, as well as alternative algorithms for l\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">p</sub>\\n norms and other spaces.\",\n \"Title: Sampling Methods for Counting Temporal Motifs.\\nYear: 2019\\n\\nAbstract: Pattern counting in graphs is fundamental to several network sci- ence tasks, and there is an abundance of scalable methods for estimating counts of small patterns, often called motifs, in large graphs. However, modern graph datasets now contain richer structure, and incorporating temporal information in particular has become a key part of network analysis. Consequently, temporal motifs, which are generalizations of small subgraph patterns that incorporate temporal ordering on edges, are an emerging part of the network analysis toolbox. However, there are no algorithms for fast estimation of temporal motifs counts; moreover, we show that even counting simple temporal star motifs is NP-complete. Thus, there is a need for fast and approximate algorithms. Here, we present the first frequency estimation algorithms for counting temporal motifs. More specifically, we develop a sampling framework that sits as a layer on top of existing exact counting algorithms and enables fast and accurate memory-efficient estimates of temporal motif counts. Our results show that we can achieve one to two orders of magnitude speedups over existing algorithms with minimal and controllable loss in accuracy on a number of datasets.\",\n \"Title: Local Global Tradeoffs in Metric Embeddings\\nYear: 2010\\n\\nAbstract: Suppose that every k points in a metric space X are D-distortion embeddable into \\\\ell _1. We give upper and lower bounds on the distortion required to embed the entire space X into \\\\ell _1. This is a natural mathematical question and is also motivated by the study of relaxations obtained by lift-and-project methods for graph partitioning problems. In this setting, we show that X can be embedded into \\\\ell _1 with distortion {\\\\rm O}(D \\\\times \\\\log (\\\\left| X \\\\right|/k)). Moreover, we give a lower bound showing that this result is tight if D is bounded away from 1. For D = 1 + \\\\delta we give a lower bound of \\\\Omega (\\\\log (\\\\left| X \\\\right|/k)/\\\\log (1/\\\\delta )); and for D = 1, we give a lower bound of \\\\Omega (\\\\log \\\\left| X \\\\right|/(\\\\log k + \\\\log \\\\log \\\\left| X \\\\right|)). Our bounds significantly improve on the results of Arora, Lovész, Newman, Rabani, Rabinovich and Vempala, who initiated a study of these questions.\",\n \"Title: A Hitting Time Analysis of Stochastic Gradient Langevin Dynamics.\\nYear: 2017\\n\\nAbstract: We study the Stochastic Gradient Langevin Dynamics (SGLD) algorithm for non-convex optimization. The algorithm performs stochastic gradient descent, where in each step it injects appropriately scaled Gaussian noise to the update. We analyze the algorithmu0027s hitting time to an arbitrary subset of the parameter space. Two results follow from our general theory: First, we prove that for empirical risk minimization, if the empirical risk is point-wise close to the (smooth) population risk, then the algorithm achieves an approximate local minimum of the population risk in polynomial time, escaping suboptimal local minima that only exist in the empirical risk. Second, we show that SGLD improves on one of the best known learnability results for learning linear classifiers under the zero-one loss.\",\n \"Title: Multi-Commodity Flow with In-Network Processing.\\nYear: 2018\\n\\nAbstract: Modern networks run that offer services ranging from network address translation and server load balancing to firewalls, encryption, and compression. In an industry trend known as Network Functions Virtualization (NFV), these middleboxes run as virtual machines on any commodity server, and the switches steer traffic through the relevant chain of services. Network administrators must decide how many middleboxes to run, where to place them, and how to direct traffic through them, based on the traffic load and the server and network capacity. Rather than placing specific kinds of middleboxes on each processing node, we argue that server virtualization allows each server node to host all middlebox functions, and simply vary the fraction of resources devoted to each one. This extra flexibility fundamentally changes the optimization problem the network administrators must solve to a new kind of multi-commodity flow problem, where the traffic flows consume bandwidth on the links as well as processing resources on the nodes. We show that allocating resources to maximize the processed flow can be optimized exactly via a linear programming formulation, and to arbitrary accuracy via an efficient combinatorial algorithm. Our experiments with real traffic and topologies show that a joint optimization of node and link resources leads to an efficient use of bandwidth and processing capacity. We also study a class of design problems that decide where to provide node capacity to best process and route a given set of demands, and demonstrate both approximation algorithms and hardness results for these problems.\",\n \"Title: The One-Way Communication Complexity of Dynamic Time Warping Distance.\\nYear: 2019\\n\\nAbstract: We resolve the randomized one-way communication complexity of Dynamic Time Warping (DTW) distance. We show that there is an efficient one-way communication protocol using $widetilde{O}(n/alpha)$ bits for the problem of computing an $alpha$-approximation for DTW between strings $x$ and $y$ of length $n$, and we prove a lower bound of $Omega(n / alpha)$ bits for the same problem. Our communication protocol works for strings over an arbitrary metric of polynomial size and aspect ratio, and we optimize the logarithmic factors depending on properties of the underlying metric, such as when the points are low-dimensional integer vectors equipped with various metrics or have bounded doubling dimension. We also consider linear sketches of DTW, showing that such sketches must have size $Omega(n)$.\",\n \"Title: Efficient Profile Maximum Likelihood for Universal Symmetric Property Estimation.\\nYear: 2019\\n\\nAbstract: Estimating symmetric properties of a distribution, e.g. support size, coverage, entropy, distance to uniformity, are among the most fundamental problems in algorithmic statistics. While these properties have been studied extensively and separate optimal estimators have been produced, in striking recent work Acharya et al. provided a single estimator that is competitive for each. They showed that the value of the property on the distribution that approximately maximizes profile likelihood (PML), i.e. the probability of observed frequency of frequencies, is sample competitive with respect to a broad class of estimators. Unfortunately, prior to this work, there was no known polynomial time algorithm to compute such an approximation or use PML to obtain a universal plug-in estimator. \\n\\nIn this paper we provide an algorithm that, given n samples from a distribution, computes an approximate PML distribution up to a multiplicative error of exp(n2/3 poly log(n)) in nearly linear time. Generalizing work of Acharya et al. we show that our algorithm yields a universal plug-in estimator that is competitive with a broad range of estimators up to accuracy є = Ω(n−0.166). Further, we provide efficient polynomial-time algorithms for computing a d-dimensional generalization of PML (for constant d) that allows for universal plug-in estimation of symmetric relationships between distributions.\",\n \"Title: Rehashing Kernel Evaluation in High Dimensions\\nYear: 2019\\n\\nAbstract: Kernel methods are effective but do not scale well to large scale data, especially in high dimensions where the geometric data structures used to accelerate kernel evaluation suffer from the curse of dimensionality. Recent theoretical advances have proposed fast kernel evaluation algorithms leveraging hashing techniques with worst-case asymptotic improvements. However, these advances are largely confined to the theoretical realm due to concerns such as super-linear preprocessing time and diminishing gains in non-worst case datasets. In this paper, we close the gap between theory and practice by addressing these challenges via provable and practical procedures for adaptive sample size selection, preprocessing time reduction, and refined variance bounds that quantify the data-dependent performance of random sampling and hashing-based kernel evaluation methods. Our experiments show that these new tools offer up to $10\\\\times$ improvement in evaluation time on a range of synthetic and real-world datasets.\",\n \"Title: Brief Announcement: A Randomness-efficient Massively Parallel Algorithm for Connectivity\\nYear: 2021\\n\\nAbstract: ABSTRACTWe give a randomness-efficient Massively Parallel Computation (MPC) algorithm for deciding whether an undirected graph is connected. For Connectivity on n-vertex, m-edge graphs whose components have diameter at most D = 2o(log n/ log log n), our algorithm runs in R = O(log D + log logm/n,.n) rounds and uses a total of (log n)O(R) random bits, O(m) machines, and n1-Ω(1) space per machine with good probability.1 With good probability means with probability at least 1 - 1/poly ((m log n)/n), which is the same as in Liu, Tarjan, and Zhong (SPAA '20). Our algorithm achieves a super-polynomial saving in randomness complexity as compared to the breakthrough algorithm of Andoni et al. (FOCS '18) and the subsequent improvement by Behnezhad et al. (FOCS '19). Our algorithm has the same round complexity as that of Behnezhad et al., but uses more total space. Our Connectivity algorithm is an instantiation of a general method we develop for converting randomized algorithms in the PRAM model to highly randomness-efficient MPC algorithms. We show that for k = o(log n/log log n) and p = nO(1), any time-k p-processor randomized PRAM algorithm computing a function on n input bits can be converted to an equivalent strongly sublinear MPC algorithm with O(k) rounds and only a total of (log n)O(k) random bits. Our Connectivity algorithm follows from applying this method to the recent CRCW PRAM algorithm of Liu, Tarjan, and Zhong (SPAA '20). Our approach is based on the design of a pseudorandom generator for PRAM algorithms. The analysis of our generator is built on classic and influential results in circuit complexity (Hå stad '86; Nisan and Wigderson '88), which we generalize from the setting of small-depth circuits to the more powerful setting of PRAM algorithms. The parameters that we achieve are optimal given the current state of the art in complexity theory, in the sense that further improvements will imply ≠ NC1.\",\n \"Title: Metric Distortion Bounds for Randomized Social Choice\\nYear: 2022\\n\\nAbstract: Consider the following social choice problem. Suppose we have a set of $n$ voters and $m$ candidates that lie in a metric space. The goal is to design a mechanism to choose a candidate whose average distance to the voters is as small as possible. However, the mechanism does not get direct access to the metric space. Instead, it gets each voter's ordinal ranking of the candidates by distance. Given only this partial information, what is the smallest worst-case approximation ratio (known as the distortion) that a mechanism can guarantee? A simple example shows that no deterministic mechanism can guarantee distortion better than $3$, and no randomized mechanism can guarantee distortion better than $2$. It has been conjectured that both of these lower bounds are optimal, and recently, Gkatzelis, Halpern, and Shah proved this conjecture for deterministic mechanisms. We disprove the conjecture for randomized mechanisms for $m \\\\geq 3$ by constructing elections for which no randomized mechanism can guarantee distortion better than $2.0261$ for $m = 3$, $2.0496$ for $m = 4$, up to $2.1126$ as $m \\\\to \\\\infty$. We obtain our lower bounds by identifying a class of simple metrics that appear to capture much of the hardness of the problem, and we show that any randomized mechanism must have high distortion on one of these metrics. We provide a nearly matching upper bound for this restricted class of metrics as well. Finally, we conjecture that these bounds give the optimal distortion for every $m$, and provide a proof for $m = 3$, thereby resolving that case.\",\n \"Title: Polylogarithmic Sketches for Clustering\\nYear: 2022\\n\\nAbstract: Given $n$ points in $\\\\ell_p^d$, we consider the problem of partitioning points into $k$ clusters with associated centers. The cost of a clustering is the sum of $p^{\\\\text{th}}$ powers of distances of points to their cluster centers. For $p \\\\in [1,2]$, we design sketches of size poly$(\\\\log(nd),k,1/\\\\epsilon)$ such that the cost of the optimal clustering can be estimated to within factor $1+\\\\epsilon$, despite the fact that the compressed representation does not contain enough information to recover the cluster centers or the partition into clusters. This leads to a streaming algorithm for estimating the clustering cost with space poly$(\\\\log(nd),k,1/\\\\epsilon)$. We also obtain a distributed memory algorithm, where the $n$ points are arbitrarily partitioned amongst $m$ machines, each of which sends information to a central party who then computes an approximation of the clustering cost. Prior to this work, no such streaming or distributed-memory algorithm was known with sublinear dependence on $d$ for $p \\\\in [1,2)$.\",\n \"Title: Almost 3-Approximate Correlation Clustering in Constant Rounds\\nYear: 2022\\n\\nAbstract: We study parallel algorithms for correlation clustering. Each pair among n objects is labeled as either “similar” or “dissimilar”. The goal is to partition the objects into arbitrarily many clusters while minimizing the number of disagreements with the labels.Our main result is an algorithm that for any $\\\\varepsilon>0$ obtains a (3 + $\\\\varepsilon$)-approximation in $O(1/\\\\varepsilon$) rounds (of models such as massively parallel computation, local, and semi-streaming). This is a culminating point for the rich literature on parallel correlation clustering. On the one hand, the approximation (almost) matches a natural barrier of 3 for combinatorial algorithms. On the other hand, the algorithm’s round-complexity is essentially constant.To achieve this result, we introduce a simple $O(1/\\\\varepsilon$)-round parallel algorithm. Our main result is to provide an analysis of this algorithm, showing that it achieves a (3 + $\\\\varepsilon$)-approximation. Our analysis draws on new connections to sublinear-time algorithms. Specifically, it builds on the work of Yoshida, Yamamoto, and Ito [1] on bounding the “query complexity” of greedy maximal independent set. To our knowledge, this is the first application of this method in analyzing the approximation ratio of any algorithm.Full version. Due to the page limit, this version of the paper does not include all the proofs. The full version of the paper is available at [2].\"\n]","isConversational":false},"profile_size":{"kind":"number","value":110,"string":"110"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":243,"string":"243"}}},{"rowIdx":244,"cells":{"question_id":{"kind":"string","value":"David E Culler"},"question":{"kind":"string","value":"Generate an abstract for the title \"Quantitative methods for comparing different HVAC control schemes\" using the following items: 1. Energy usage \n2. Comfort characteristics \n3. Controllers \n4. HVAC systems \n5. Experimental case studies"},"answer":{"kind":"string","value":"Experimentally comparing the energy usage and comfort characteristics of different controllers in heating, ventilation, and air-conditioning (HVAC) systems is difficult because variations in weather and occupancy conditions preclude the possibility of establishing equivalent experimental conditions across the order of hours, days, and weeks. This paper is concerned with defining quantitative metrics of energy usage and occupant comfort, which can be computed and compared in a rigorous manner that is capable of determining whether differences between controllers are statistically significant in the presence of such environmental fluctuations. Experimental case studies are presented that compare two alternative controllers (a schedule controller and a hybrid system learning-based model predictive controller) to the default controller in a building-wide HVAC system. Lastly, we discuss how our proposed methodology may also be able to quantify the efficiency of other building automation systems."},"correct_answer":{"kind":"string","value":"Experimentally comparing the energy usage and comfort characteristics of different controllers in heating, ventilation, and air-conditioning (HVAC) systems is difficult because variations in weather and occupancy conditions preclude the possibility of establishing equivalent experimental conditions across the order of hours, days, and weeks. This paper is concerned with defining quantitative metrics of energy usage and occupant comfort, which can be computed and compared in a rigorous manner that is capable of determining whether differences between controllers are statistically significant in the presence of such environmental fluctuations. Experimental case studies are presented that compare two alternative controllers (a schedule controller and a hybrid system learning-based model predictive controller) to the default controller in a building-wide HVAC system. Lastly, we discuss how our proposed methodology may also be able to quantify the efficiency of other building automation systems."},"documents":{"kind":"list like","value":["Title: TAM—a compiler controlled threaded abstract machine\nYear: 1993\n\nAbstract: The Threaded Abstract Machine (TAM) refines dataflow execution models to address the critical constraints that modern parallel architectures place on th e compilation of general-purpose parallel programming languages. TAM defines a self-scheduled machine language ofparallel threads, which provides a path from dataflow- graph program representations to conventional control flow . The most important feature of TAM is the way it exposes the interaction between the handling of asynchronous message events, the scheduling of computation, and the utilizati on of the storage hierarchy. This paper provides a complete description of TAM and codifies the model in terms of a pseudo machine language TL0. Issues in compilation from a high level parallel language to TL0 are discussed in general and specifically in regard to the Id90 language. The implementation of TL0 on the CM-5 multiprocessor is explained in detail. Using this implementation, a cost model is developed for the various TAM primitives. The TAM approach is evaluated on sizable Id90 programs on a 64 processor system. The scheduling hierarchy of quanta and threads is shown to provide substantial locality while tolerating long latencies. Thi s allows the average thread scheduling cost to be extremely l ow.","Title: Active Sensor Networks\nYear: 2005\n\nAbstract: We propose using application specific virtual machines (ASVMs) to reprogram deployed wireless sensor networks. ASVMs provide a way for a user to define an application- specific boundary between virtual code and the VM en- gine. This allows programs to be very concise (tens to hundreds of bytes), making program installation fast and inexpensive. Additionally, concise programs interpret few instructions, imposing very little interpretation over- head. We evaluate ASVMs against current proposals for network programming runtimes and show that ASVMs are more energy efficient by as much as 20%. We also evaluate ASVMs against hand built TinyOS applications and show that while interpretation imposes a significant execution overhead, the low duty cycles of realistic ap- plications make the actual cost effectively unmeasurable.","Title: The firecracker protocol\nYear: 2004\n\nAbstract: We propose the Firecracker protocol for data dissemi- nation in wireless sensor networks. Firecracker uses a combination of routing and broadcasts to rapidly deliver a piece of data to every node in a network. To start dis- semination, the data source sends data to distant points in the network. Once the data reaches its destinations, broadcast-based dissemination begins along the paths, like a string of firecrackers. By using an initial routing phase, Firecracker can dis- seminate at a faster rate than scalable broadcasts while sending fewer packets. The selection of points to route to has a large effect on performance, indicating possible requirements for any-to-any routing protocols in wireless sensor networks.","Title: Scheduling with implicit information in distributed systems\nYear: 1998\n\nAbstract: Implicit coscheduling is a distributed algorithm for time-sharing communicating processes in a cluster of workstations. By observing and reacting to implicit information, local schedulers in the system make independent decisions that dynamically coordinate the scheduling of communicating processes. The principal mechanism involved is two-phase spin-blocking: a process waiting for a message response spins for some amount of time, and then relinquishes the processor if the response does not arrive.In this paper, we describe our experience implementing implicit coscheduling on a cluster of 16 UltraSPARC I workstations; this has led to contributions in three main areas. First, we more rigorously analyze the two-phase spin-block algorithm and show that spin time should be increased when a process is receiving messages. Second, we present performance measurements for a wide range of synthetic benchmarks and for seven Split-C parallel applications. Finally, we show how implicit coscheduling behaves under different job layouts and scaling, and discuss preliminary results for achieving fairness.","Title: Design Of An Application-Cooperative Management System For Wireless Sensor Networks\nYear: 2005\n\nAbstract: This paper argues for the usefulness of an application-cooperative interactive management system for wireless sensor networks, and presents SNMS, a Sensor Network Management System. SNMS is designed to be simple and have minimal impact on memory and network traffic, while remaining open and flexible. The system is evaluated in light of issues derived from real deployment experiences.","Title: Assessing Fast Network Interfaces\nYear: 1996\n\nAbstract: Assessing the performance of emerging high-speed networks is difficult. Our communication microbenchmark evaluates design changes in a communications system. Our microbenchmark generates a graphical signature from which we extract communication performance parameters for the hardware-software tandem. We use the LogP conceptual model for communication systems. (LogP stands for the parameters latency, overhead, gap, and processors). We study three important platforms that represent diverse points in the network interface design space: the Intel Paragon, Meiko CS-2, and a cluster of Sparcstation-20s connected by Myrinet switches using LANai SBus cards. Our study views each machine as a gray box supporting Active Messages and conforming to the LogP framework. We devise a simple set of communication microbenchmarks and measure the performance on each platform to obtain the LogP parameters","Title: Modeling communication pipeline latency\nYear: 1998\n\nAbstract: In this paper, we study how to minimize the latency of a message through a network that consists of a number of store-and-forward stages. This research is especially relevant for today's low overhead communication systems that employ dedicated processing elements for protocol processing. We develop an abstract pipeline model that reveals a crucial performance tradeoff involving the effects of the overhead of the bottleneck stage and the bandwidth of the remaining stages. We exploit this tradeoff to develop a suite of fragmentation algorithms designed to minimize message latency. We also provide an experimental methodology that enables the construction of customized pipeline algorithms that can adapt to the specific system characteristics and application workloads. By applying this methodology to the Myrinet-GAM system, we have improved its latency by up to 51%. Our theoretical framework is also applicable to pipelined systems beyond the context of high speed networks.","Title: Wide Area Cluster Monitoring With Ganglia\nYear: 2003\n\nAbstract: In this paper, we present a structure for monitoring a large set of computational clusters. We illustrate methods for scaling a monitor network comprised of many clusters while keeping processing requirements low. A design for presenting high-level web-based summaries of the monitor network is provided, along with a generalization to a distributed, multiple-resolution monitoring tree. Emphasis is placed on scalability, fast query response, fault tolerance, and grid compatibility. Experimental evidence is presented that demonstrates the performance of our design.","Title: The explicit token store\nYear: 1990\n\nAbstract: This paper presents an unusually simple approach to dynamic dataflow execution, called the Explicit Token Store (ETS) architecture, and its current realization in Monsoon. The essence of dynamic dataflow execution is captured by a simple transition on state bits associated with storage local to a processor. Low-level storage management is performed by the compiler in assigning nodes to slots in an activation frame, rather than dynamically in hardware. The processor is simple, highly pipelined, and quite general. There is exactly one instruction executed for each action on the dataflow graph. Thus, the machine-oriented ETS model provides new insight into the real cost of direct execution of dataflow graphs.","Title: The Mantis parallel debugger\nYear: 1996\n\nAbstract: Parallel tools often fail to integrate effectively with other parallel systems, exacerbating the inherent difficulty of programming a massively parallel machine. Successful parallel debugging requires the rethinking of traditional debugging goals in the context of parallelism. The following four objectives: rapid focus, scalability, economy of presentation, and portability, represent the more difficult aspects of parallel debugging. In light of these specific goals, this paper presents Mantis,...","Title: Analysis of multithreaded microprocessors under multiprogramming\nYear: 1992\n\nAbstract: We examine multithreading to improve uniprocessor cost/performance on multiple processes. Processor utilization and cache behavior are studied analytically and under simulation by interleaving reference traces to model timesharing and multithreading. Multithreading a small number of threads is superior with large on-chip caches and significant memory latency. The switch need not be extremely fast. Surprisingly, miss ratios under multithreading may be lower than under timesharing, because switch-on-miss multithreading favors processes with better cache behavior.","Title: Searching for the sorting record: experiences in tuning NOW-Sort\nYear: 1998\n\nAbstract: We present our experiences in developing and tuning the performanceof NOW-Sort, a parallel, disk-to-disk sorting algorithm.NOW-Sort currently holds two world records in databaseindustrystandard benchmarks. Critical to the tuning processwas the setting of expectations, which tell the programmer bothwhere to tune and when to stop. We found three categories ofuseful tools: tools that help set expectations and configurethe application to different hardware parameters, visualizationtools...","Title: Effects of communication latency, overhead, and bandwidth in a cluster architecture\nYear: 1997\n\nAbstract: This work provides a systematic study of the impact of communication performance on parallel applications in a high performance network of workstations. We develop an experimental system in which the communication latency, overhead, and bandwidth can be independently varied to observe the effects on a wide range of applications. Our results indicate that current efforts to improve cluster communication performance to that of tightly integrated parallel machines results in significantly improved application performance. We show that applications demonstrate strong sensitivity to overhead, slowing down by a factor of 60 on 32 processors when overhead is increased from 3 to 103 µs. Applications in this study are also sensitive to per-message bandwidth, but are surprisingly tolerant of increased latency and lower per-byte bandwidth. Finally, most applications demonstrate a highly linear dependence to both overhead and per-message bandwidth, indicating that further improvements in communication performance will continue to improve application performance.","Title: An Analysis Of Vi Architecture Primitives In Support Of Parallel And Distributed Communication\nYear: 2002\n\nAbstract: We present the results of a detailed study of the Virtual Interface (VI) paradigm as a communication foundation for a distributed computing environment. Using Active Messages and the Split-C global memory model, we analyze the inherent costs of using VI primitives to implement these high-level communication abstractions. We demonstrate a minimum mapping cost (i.e. the host processing required to map one abstraction to a lower abstraction) of 5.4 mus for both Active Messages and Split-C using four-way 550 MHz Pentium III SMPs and the Myrinet network. We break down this cost to the use of individual VI primitives in supporting flow control, buffer management and event processing and identify the completion queue as the source of the highest overhead. Bulk transfer performance plateaus at 44 Mbytes/s for both implementations are due to the addition of fragmentation requirements. Based on this analysis, we present the implications for the VI successor, Infiniband. Copyright (C) 2002 John Wiley Sons, Ltd.","Title: A Network-Centric Approach to Embedded Software for Tiny Devices\nYear: 2001\n\nAbstract: The ability to incorporate low-power, wireless communication into embedded devices gives rise to a newgenre of embedded software that is distributed, dynamic, and adaptive. This paper describes the network-centric approach to designing software for highly constrained devices embodied in TinyOS. It develops a tiny Active Message communication model and shows how it is used to build non-blocking applications and higher level networking capabilities, such as multihop ad hoc routing. It shows how the TinyOS event-driven approach is used to tackle challenges in implementing the communication model with very limited storage and the radio channel modulated directly in software in an energy efficient manner. The open, component-based design allows many novel relationships between system and application.","Title: A blueprint for introducing disruptive technology into the Internet\nYear: 2003\n\nAbstract: This paper argues that a new class of geographically distributed network services is emerging, and that the most effective way to design, evaluate, and deploy these services is by using an overlay-based testbed. Unlike conventional network testbeds, however, we advocate an approach that supports both researchers that want to develop new services, and clients that want to use them. This dual use, in turn, suggests four design principles that are not widely supported in existing testbeds: services should be able to run continuously and access a slice of the overlay's resources, control over resources should be distributed, overlay management services should be unbundled and run in their own slices, and APIs should be designed to promote application development. We believe a testbed that supports these design principles will facilitate the emergence of a new service-oriented network architecture. Towards this end, the paper also briefly describes PlanetLab, an overlay network being designed with these four principles in mind.","Title: Effective distributed scheduling of parallel workloads\nYear: 1996\n\nAbstract: We present a distributed algorithm for time-sharing parallel workloads that is competitive with coscheduling. Implicit scheduling allows each local scheduler in the system to make independent decisions that dynamically coordinate the scheduling of cooperating processes across processors. Of particular importance is the blocking algorithm which decides the action of a process waiting for a communication or synchronization event to complete. Through simulation of bulk-synchronous parallel applications, we find that a simple two-phase fixed-spin blocking algorithm performs well; a two-phase adaptive algorithm that gathers run-time data on barrier wait-times performs slightly better. Our results hold for a range of machine parameters and parallel program characteristics. These findings are in direct contrast to the literature that states explicit coscheduling is necessary for fine-grained programs. We show that the choice of the local scheduler is crucial, with a priority-based scheduler performing two to three times better than a round-robin scheduler. Overall, we find that the performance of implicit scheduling is near that of coscheduling (+/- 35%), without the requirement of explicit, global coordination.","Title: The impact of flexible loads in increasingly renewable grids.\nYear: 2013\n\nAbstract: We develop a flexible and responsive electrical load in the form of domestic refrigerators augmented with a thermal storage system, a wireless sensor network for monitoring and actuation, and a controller that enables response to external controls. Using this, we investigate the potential of such loads for two applications: price-responsive demand and supply-following. Our prototype shows that with a 13% increase in refrigerator electricity consumption, we are able to avoid electricity consumption for over six hours. We employ a methodology for creating models of electricity grids with high renewables penetration, and study the effects of deploying variable populations of flexible energy storage refrigerators in grids at variable levels of renewables penetration. Our results show that our prototype can respond to time-of-use price tariffs to reduce summer refrigeration electricity cost by up to 13% on the consumer side, while substantially reducing the capital investment on the utility side by smoothing the peak. At higher levels of renewables penetration, with 20% of refrigerators in California adopting this technology and acting as supply-following electricity loads, flexible refrigerators can shave off 5% of peak capacity needs. The approach naturally extends to similar applications in thermal management of buildings and would operate in concert with other load management efforts such as smart vehicle charging.","Title: A transmission control scheme for media access in sensor networks\nYear: 2001\n\nAbstract: We study the problem of media access control in the novel regime of sensor networks, where unique application behavior and tight constraints in computation power, storage, energy resources, and radio technology have shaped this design space to be very different from that found in traditional mobile computing regime. Media access control in sensor networks must not only be energy efficient but should also allow fair bandwidth allocation to the infrastructure for all nodes in a multihop network. We propose an adaptive rate control mechanism aiming to support these two goals and find that such a scheme is most effective in achieving our fairness goal while being energy efficient for both low and high duty cycle of network traffic.","Title: Lessons from a Sensor Network Expedition\nYear: 2004\n\nAbstract: Habitat monitoring is an important driving application for wireless sensor networks (WSNs). Although researchers anticipate some challenges arising in the real-world deployments of sensor networks, a number of problems can be discovered only through experience. This paper evaluates a sensor network system described in an earlier work and presents a set of experiences from a four month long deployment on a remote island off the coast of Maine. We present an in-depth analysis of the environmental and node health data. The close integration of WSNs with. their environment provides biological data at densities previous impossible; however, we show that the sensor data is also useful for predicting system operation and network failures. Based on over one million data and health readings, we analyze the node and network design and develop network reliability profiles and failure models.","Title: Cluster I/O with River: making the fast case common\nYear: 1999\n\nAbstract: We introduce River, a data-flow programming environment and I/O substrate for clusters of computers. River is designed to provide max- imum performance in the common case — even in the face of non- uniformities in hardware, software, and workload. River is based on two simple design features: a high-performance distributed queue, and a storage redundancy mechanism called graduated declustering. We have implemented a number of data-intensive applications on River, which validate our design with near-ideal performance in a variety of non-uniform performance scenarios.","Title: Guest Editors' Introduction: Overview of Sensor Networks\nYear: 2004\n\nAbstract: Wireless sensor networks could advance many scientific pursuits while providing a vehicle for enhancing various forms of productivity, including manufacturing, agriculture, construction, and transportation.","Title: Operating system support for planetary-scale network services\nYear: 2004\n\nAbstract: PlanetLab is a geographically distributed overlay network designed to support the deployment and evaluation of planetary-scale network services. Two high-level goals shape its design. First, to enable a large research community to share the infrastructure, PlanetLab provides distributed virtualization, whereby each service runs in an isolated slice of PlanetLab's global resources. Second, to support competition among multiple network services, PlanetLab decouples the operating system running on each node from the network-wide services that define PlanetLab, a principle referred to as unbundled management. This paper describes how Planet-Lab realizes the goals of distributed virtualization and unbundled management, with a focus on the OS running on each node.","Title: Ninja: A Framework for Network Services\nYear: 2002\n\nAbstract: Ninja is a new framework that makes it easy to create robust scalable Internet services. We introduce a new programming model based on the natural parallelism qflarge-scale services, and show how to implement the model. The first key aspect of the model is intelligent connection management, which enables high availability, load balancing, graceful degradation and online evolution. The second key aspect is support for shared persistent state that is automatically partitioned for scalability and replicated for fault tolerance. We discuss two versions of shared state, a cluster-based hash table with transparent replication and novel features that reduce lock contention, and a cluster-based file system that provides local transactions and cluster-wide namespaces and replication. Using several applications we show that the framework enables the creation of scalable, highly available services with persistent data, with very little application code - as little as one-tenth the code size of comparable stand-alone applications.","Title: Separation constraint partitioning: a new algorithm for partitioning non-strict programs into sequential threads\nYear: 1995\n\nAbstract: In this paper we present substantially improved thread partitioning algorithms for modern implicitly parallel languages. We present a new block partitioning algorithm, separation constraint partitioning, which is both more powerful and more flexible than previous algorithms. Our algorithm is guaranteed to derive maximal threads. We present a theoretical framework for proving the correctness of our partitioning approach, and we show how separation constraint partitioning makes interprocedural partitioning viable.We have implemented the partitioning algorithms in an Id90 compiler for workstations and parallel machines. Using this experimental platform, we quantify the effectiveness of different partitioning schemes on whole applications.","Title: Lazy threads: implementing a fast parallel call\nYear: 1996\n\nAbstract: In this paper, we describe lazy threads, a new approach for implementing multithreaded execution models on conventional machines. We show how they can implement a parallel call at nearly the efficiency of a sequential call. The central idea is to specialize the representation of a parallel call so that it can execute as a parallel-ready sequential call. This allows excess parallelism to degrade into sequential calls with the attendant efficient stack management and direct transfer of control and data, yet a call that truly needs to execute in parallel, gets its own thread of control. The efficiency of lazy threads is achieved through a careful attention to storage management and a code generation strategy that allows us to represent potential parallel work with no overhead. © 1996 Academic Press, Inc.","Title: PlanetLab: an overlay testbed for broad-coverage services\nYear: 2003\n\nAbstract: PlanetLab is a global overlay network for developing and accessing broad-coverage network services. Our goal is to grow to 1000 geographically distributed nodes, connected by a disverse collection of links. PlanetLab allows multiple service to run concurrently and continuously, each in its own slice of PlanetLab. This paper discribes our initial implementation of PlanetLab, including the mechanisms used to impelment virtualization, and the collection of core services used to manage PlanetLab.","Title: Empirical evaluation of the CRAY-T3D: a compiler perspective\nYear: 1995\n\nAbstract: Most recent MPP systems employ a fast microprocessor surrounded by a shell of communication and synchronization logic. The CRAY-T3D provides an elaborate shell to support global-memory access, prefetch, atomic operations, barriers, and block transfers. We provide a detailed empirical performance characterization of these primitives using micro-benchmarks and evaluate their utility in compiling for a parallel language. We have found that the raw performance of the machine is quite impressive and the most effective forms of communication are prefetch and write. Other shell provisions, such as the bulk transfer engine and the external Annex register set, are cumbersome and of little use. By evaluating the system in the context of a language implementation, we shed light on important trade-offs and pitfalls in the machine architecture.","Title: Integrating concurrency control and energy management in device drivers\nYear: 2007\n\nAbstract: Energy management is a critical concern in wireless sensornets. Despite its importance, sensor network operating systems today provide minimal energy management support, requiring applications to explicitly manage system power states. To address this problem, we present ICEM, a device driver architecture that enables simple, energy efficient wireless sensornet applications. The key insight behind ICEMis that the most valuable information an application can give the OS for energy management is its concurrency. Using ICEM, a low-rate sensing application requires only a single line of energy management code and has an efficiency within 1.6% of a hand-tuned implementation. ICEM's effectiveness questions the assumption that sensornet applications must be responsible for all power management and sensornets cannot have a standardized OS with a simple API.","Title: Flexibility of Commercial Building HVAC Fan as Ancillary Service for Smart Grid.\nYear: 2013\n\nAbstract: In this paper, we model energy use in commercial buildings using empirical data captured through sMAP, a campus building data portal at UC Berkeley. We conduct at-scale experiments in a newly constructed building on campus. By modulating the supply duct static pressure (SDSP) for the main supply air duct, we induce a response on the main supply fan and determine how much ancillary power flexibility can be provided by a typical commercial building. We show that the consequent intermittent fluctuations in the air mass flow into the building does not influence the building climate in a human-noticeable way. We estimate that at least 4 GW of regulation reserve is readily available only through commercial buildings in the US. Based on predictions this value will reach to 5.6 GW in 2035. We also show how thermal slack can be leveraged to provide an ancillary service to deal with transient frequency fluctuations in the grid. We consider a simplified model of the grid power system with time varying demand and generation and present a simple control scheme to direct the ancillary service power flow from buildings to improve on the classical automatic generation control (AGC)-based approach. Simulation results are provided to show the effectiveness of the proposed methodology for enhancing grid frequency regulation.","Title: Building MPI for Multi-Programming Systems Using Implicit Information\nYear: 1999\n\nAbstract: With the growing importance of fast system area networks in the parallel community, it is becoming common for message passing programs to run in multi-programming environments. Competing sequential and parallel jobs can distort the global coordination of communicating processes. In this paper, we describe our implementation of MPI using implicit information for global coscheduling. Our results show that MPI program performance is, indeed, sensitive to local scheduling variations. Further, the integration of implicit co-scheduling with the MPI runtime system achieves robust performance in a multiprogramming environment, without compromising performance in dedicated use.","Title: Data Compression Technology Dedicated to Distribution and Embedded Systems\nYear: 2010\n\nAbstract: Summary form only given. In distribution and embedded systems, data compression is often used to reduce the size of flash RAM and transmission data, while a rapid decompression speed enables faster rebooting of the compressed program code. We have developed a new data compression algorithm with a high decompression speed and a good compression rate that is equivalent to zlib, the standard technology in use today. We created a LZSS-based algorithm by optimizing the parsing of data strings. LZSS is known as a high decompression speed algorithm useful for embedded systems, and optimal parsing is well known as a method for improving compression rates. Previously, this combination had not been implemented because statistical code length varies during optimal parsing. Our algorithm overcomes this problem by calculating the probability of the literal or the code ( distance and length ) solving the shortest path problem first. It then constructs a simple code set that enables fast decompression using those probabilities and solves the shortest path problem again. Experiments on the standard evaluation data and wireless sensor network program demonstrated that we can achieve a high compression rate equivalent to zlib and a decompression speed that is twice as fast.","Title: Compiler-controlled multithreading for lenient parallel languages\nYear: 1991\n\nAbstract: Tolerance to communication latency and inexpensive synchronization are critical for general-purpose computing on large multiprocessors. Fast dynamic scheduling is required for powerful non-strict parallel languages. However, machines that support rapid switching between multiple execution threads remain a design challenge. This paper explores how multithreaded execution can be addressed as a compilation problem, to achieve switching rates approaching what hardware mechanisms might provide. Compiler-controlled multithreading is examined through compilation of a lenient parallel language, Id90, for a threaded abstract machine, TAM. A key feature of TAM is that synchronization is explicit and occurs only at the start of a thread, so that a simple cost model can be applied. A scheduling hierarchy allows the compiler to schedule logically related threads closely together in time and to use registers across threads. Remote communication is via message sends and split-phase memory accesses. Messages and memory replies are received by compiler-generated message handlers which rapidly integrate these events with thread scheduling. To compile Id90for TAM, we employ a new parallel intermediate form, dual-graphs, with distinct control and data arcs. This provides a clean framework for partitioning the program into threads, scheduling threads, and managing registers under asynchronous execution. The compilation process is described and preliminary measurements show that the cost of compiler-controlled multithreading is within a small factor of the cost of control flow in sequential languages.","Title: Introduction to the Special Section on Dependable Network Computing\nYear: 2001\n\nAbstract: First Page of the Article","Title: U-Net/SLE: A Java-based user-customizable virtual network interface\nYear: 1999\n\nAbstract: We describe U-Net/SLE (Safe Language Extensions), a user-level network interface architecture which enables per-application customization of communication semantics through downloading of user extension applets, implemented as Java classfiles, to the network interface. This architecture permits applications to safely specify code to be executed within the NI on message transmission and reception. By leveraging the existing U-Net model, applications may implement protocol code at the user level, within the NI, or using some combination of the two. Our current implementation, using the Myricom Myrinet interface and a small Java Virtual Machine subset, allows host communication overhead to be reduced and improves the overlap of communication and computation during protocol processing.","Title: Achieving Robust, Scalable Cluster I/O in Java\nYear: 2000\n\nAbstract: We present Tigris, a high-performance computation and I/O substrate for clusters of workstations that is implemented entirely in Java. Tigris automatically balances resource load across the cluster as a whole, shielding applications from asymmetries in CPU, I/O, and network performance. This is accomplished through the use of a dataflow programming model coupled with a work-balancing distributed queue. To meet the performance challenges of implementing such a system in Java, Tigris relies on Jaguar, a system that enables direct, protected access to hardware resources, including fast network interfaces and disk I/O. Jaguar yields an order-of-magnitude performance boost over the Java Native Interface for Java bindings to system resources. We demonstrate the applicability of Tigris through a one-pass, parallel, disk-to-disk sort exhibiting high performance.","Title: IP is dead, long live IP for wireless sensor networks\nYear: 2008\n\nAbstract: A decade ago as wireless sensor network research took off many researchers in the field denounced the use of IP as inadequate and in contradiction to the needs of wireless sensor networking. Since then the field has matured, standard links have emerged, and IP has evolved. In this paper, we present the design of a complete IPv6-based network architecture for wireless sensor networks. We validate the architecture with a production-quality implementation that incorporates many techniques pioneered in the sensor network community, including duty-cycled link protocols, header compression, hop-by-hop forwarding, and efficient routing with effective link estimation. In addition to providing interoperability with existing IP devices, this implementation was able to achieve an average duty-cycle of 0.65%, average per-hop latency of 62ms, and a data reception rate of 99.98% over a period of 4 weeks in a real-world home-monitoring application where each node generates one application packet per minute. Our results outperform existing systems that do not adhere to any particular standard or architecture. In light of this demonstration of full IPv6 capability, we review the central arguments that led the field away from IP. We believe that the presence of an architecture, specifically an IPv6-based one, provides a strong foundation for wireless sensor networks going forward.","Title: The Ten Hottest Topics in Parallel and Distributed Computing for the Next Millennium\nYear: 2000\n\nAbstract: What will be the fundamental issues and ideas that will define parallel and distributed computing during the next millennium? In this panel, a group of distinguished researchers will make the case for their candidates. You decide whether you agree, or stand up and make the case for the ideas that you think are important! The panelists include noted and opinionated experts in parallel computing, distributed-computing, and applications, so the discussion is guaranteed to be lively and informative.","Title: Design And Implementation Of A Sensor Network System For Vehicle Tracking And Autonomous Interception\nYear: 2005\n\nAbstract: We describe the design and implementation of PEG, a networked system of distributed sensor nodes that detects an uncooperative agent called the evader and assists an autonomous robot called the pursuer in capturing the evader. PEG requires embedded network services such as leader election, routing, network aggregation, and closed loop control. Instead of using general purpose distributed system solutions for these services, we employ whole-system analysis and rely on spatial and physical properties to create simple and efficient mechanisms. We believe this approach advances sensor network design, yielding pragmatic solutions that leverage physical properties to simplify design of embedded distributed systems.We deployed PEG on a 400 square meter field using 100 sensor nodes, and successfully intercepted the evader in all runs. We confronted practical issues such as node breakage, packaging decisions, in situ debugging, network reprogramming, and system reconfiguration. We discuss the approaches we took to cope with these issues and share our experiences in deploying a realistic outdoor sensor network system.","Title: Software design patterns for TinyOS\nYear: 2007\n\nAbstract: We present design patterns used by software components in the TinyOS sensor network operating system. They differ significantly from traditional software design patterns because of the constraints of sensor networks and to TinyOS's focus on static allocation and whole-program composition. We describe how nesC has evolved to support these design patterns by including a few simple language primitives and optimizations.","Title: Architectural requirements and scalability of the NAS parallel benchmarks\nYear: 1999\n\nAbstract: We present a study of the architectural requirements and scalability of the NAS Parallel Benchmarks. Through direct measurements and simulations, we identify the factors which affect the scalability of benchmark codes on two relevant and distinct platforms; a cluster of workstations and a ccNUMA SGI Origin 2000. We find that the benefit of increased global cache size is pronounced in certain applications and often offsets the communication cost. By constructing the working set profile of the benchmarks, we are able to visualize the improvement of computational efficiency under constant-problem-size scaling. We also find that, while the Origin MPI has better point-to-point performance, the cluster MPI layer is more scalable with communication load. However, communication performance within the applications is often much lower than what would be achieved by micro-benchmarks. We show that the communication protocols used by MPI runtime library are influential to the communication performance in applications, and that the benchmark codes have a wide spectrum of communication requirements.","Title: User-Centric Performance Analysis of Market-Based Cluster Batch Schedulers\nYear: 2002\n\nAbstract: This paper presents a performance analysis of market-basedbatch schedulers for clusters of workstations.In contrast to previous work, we use user-centric performance metrics as the basis for system evaluation.Each user is modeled as having a utility function for each job which measures value delivered to the user as function of execution time.Summing over all utility functions in the workload, we use aggregate utility as a measure of overall value delivered to users.With aggregate utility as the performance metric, simulations are used to quantify the performance of both market-based and traditional batch scheduling algorithms under a variety of synthetic work-loads.Results show that an auction-based batch scheduling algorithm improves performance by a factor of up to2-5x for sequential workloads and up to 14x for highly parallelworkloads compared to traditional scheduling algorithms.","Title: Toward the sensor network macroscope\nYear: 2005\n\nAbstract: The Macroscope is a conceptual instrument for perceiving complex interactions, such as what occurs is ecosystems, social systems, and large-scale industrial settings. Sensor networks are a significant step toward such an instrument, because of the fidelity they offer in monitoring large regions of space and large collections of things. This talk describes our experiences in developing and deploying a large sensor network for microclimate monitoring of coastal redwood forests as a basis for studies in redwood ecophysiology. It summarizes the architecture, its implementation, and the many lessons and surprises encountered along the way. The effort produced unprecedented recordings of the microclimate dynamics indicating how these huge organisms interact with their environment.","Title: Design challenges of virtual networks: fast, general-purpose communication\nYear: 1999\n\nAbstract: Virtual networks provide applications with the illusion of having their own dedicated, high-performance networks, although network interfaces posses limited, shared resources. We present the design of a large-scale virtual network system and examine the integration of communication programming interface, system resource management, and network interface operation. Our implementation on a cluster of 100 workstations quantifies the impact of virtualization on small message latencies and throughputs, shows full hardware performance is delivered to dedicated applications and time-shared workloads, and shows robust performance under demanding workloads that overcommit interface resources.","Title: Reducing Transient and Steady State Electricity Consumption in HVAC Using Learning-Based Model-Predictive Control.\nYear: 2012\n\nAbstract: Heating, ventilation, and air conditioning (HVAC) systems are an important target for efficiency improvements through new equipment and retrofitting because of their large energy footprint. One type of equipment that is common in homes and some offices is an electrical, single-stage heat pump air conditioner (AC). To study this setup, we have built the Berkeley Retrofitted and Inexpensive HVAC Tes...","Title: The Architectural Costs of Streaming I/O: A Comparison of Workstations, Clusters, and SMPs\nYear: 1998\n\nAbstract: We investigate resource usage while performing streaming I/O by con- trasting three architectures, a single workstation, a cluster, and an SMP, under various I/O benchmarks. We derive analytical and empirically- based models of resource usage during data transfer, examining the I/O bus, memory bus, network, and processor of each system. By investigating each resource in detail, we assess what comprises a well- balanced system for these workloads. We find that the architectures we study are not well balanced for streaming I/O applications. Across the platforms, the main limitation to attaining peak performance is the CPU, due to lack of data locality. Increasing processor performance (especially with improved block op- eration performance) will be of great aid for these workloads in the future. For a cluster workstation, the I/O bus is a major system bot- tleneck, because of the increased load placed on it from network com- munication. A well-balanced cluster workstation should have copious I/O bus bandwidth, perhaps via multiple I/O busses. The SMP suffers from poor memory-system performance; even when there is true par- allelism in the benchmark, contention in the shared-memory system leads to reduced performance. As a result, the clustered workstations provide higher absolute performance for streaming I/O workloads.","Title: Evaluation of mechanisms for fine-grained parallel programs in the J-machine and the CM-5\nYear: 1993\n\nAbstract: This paper uses an abstract machine approach to compare the mechanisms of two parallel machines: the J-Machine and the CM-5. High-level parallel programs are translated by a single optimizing compiler to a fine-grained abstract parallel machine, TAM. A final compilation step is unique to each machine and optimizes for specifics of the architecture. By determining the cost of the primitives and weighting them by their dynamic frequency in parallel programs, we quantify the effectiveness of the following mechanisms individually and in combination. Efficient processor/network coupling proves valuable. Message dispatch is found to be less valuable without atomic operations that allow the scheduling levels to cooperate. Multiple hardware contexts are of small value when the contexts cooperate and the compiler can partition the register set. Tagged memory provides little gain. Finally, the performance of the overall system is strongly influenced by the performance of the memory system and the frequency of control operations.","Title: Energy Savings and the “Software-Defined” Building\nYear: 2012\n\nAbstract: In the US buildings consume 70% of electricity, but the sector exhibits little innovation for reducing its consumption. Efficiency is not yet evaluated to the same standard as comfort and reliability, but with better user input, control policy, and awareness of the building's state, energy consumption can be intelligently reduced. It is argued that what is needed is a shift to Software-Defined Buildings: flexible, multi-service, and open Building Operating System (BOS) that allows third-party applications to run securely and reliably in a sandboxed environment. A BOS is not limited to a single building but distributed among multi-building campuses. It provides the core functionality of sensor and actuator access, access management, metadata, archiving, and discovery. The runtime environment enables multiple simultaneously running programs. As in a computer OS, these run with various privilege levels, with access to different resources, yet are multiplexed on the same physical resources. It can extend to the Cloud or to other buildings, outsourcing expensive or proprietary operations as well as load sharing, but does so safely with fail-over to local systems when connectivity is disrupted. Building operators have supervisory control over all programs, controlling the separation physically (access different controls), temporally (change controls at different times), informationally (what information leaves the building), and logically (what actions or sequences thereof are allowable).","Title: Incremental network programming for wireless sensors\nYear: 2004\n\nAbstract: We present an incremental network programming mechanism which re programs wireless sensors quickly by transmitting the incremental changes for the new program version. Using the Rsync algorithm we generate the difference of the two program images, which allows us to distribute just the key changes of the program. Unlike previous approaches, our design does not assume any prior knowledge of the program code structure and can be applied to any hardware platform. To meet the resource constraints of wireless sensors we tuned the Rsync algorithm which was originally made for updating binary files among computationally powerful machines. In our design, the sensor node processes the delivery and the decoding of the difference script in separate steps. This makes it easy to extend for multi-hop network programming. We are able to achieve the speedup of 9.1 for changing a constant and 2.1 to 2.5 for changing a few lines in the source code over the non-incremental delivery.","Title: Global analysis for partitioning non-strict programs into sequential threads\nYear: 1992\n\nAbstract: In this paper we present a new solution to the problem of compiling an eager, non-strict language into multiple sequential threads. The solution is described using an intermediate program form developed for the programming language Id [Nik90], a functional language extended with I-structures [ANP86] and M-structures [BNA91]. A similar intermediate form has also been suggested for imperative languages [BP89], as a way of exposing parallelism in those languages. With suitable restrictions, we believe our method is also appropriate for lazy, purely functional languages such as Haskell [HWe90]. Throughout this paper, a thread will mean a subset of the instructions comprising a procedure body, such that: 1. A compile-time instruction ordering can be determined for the thread which is valid for all contexts in which the containing procedure can be invoked.","Title: Flexible Hardware Abstraction For Wireless Sensor Networks\nYear: 2005\n\nAbstract: We present a flexible Hardware Abstraction Architecture (HAA) that balances conflicting requirements of Wireless Sensor Networks (WSNs) applications and the desire for increased portability and streamlined development of applications. Our three-layer design gradually adapts the capabilities of the underlying hardware platforms to the selected platform-independent hardware interface between the operating system core and the application code. At the same time, it allows the applications to utilize a platform's full capabilities - exported at the second layer, when the performance requirements outweigh the need for cross-platform compatibility. We demonstrate the practical value of our approach by presenting how it can be applied to the most important hardware modules that are found in a typical WSN platform. We support our claims using concrete examples from existing hardware abstractions in TinyOS and our implementation of the MSP430 platform that follows the architecture proposed in this paper.","Title: The ganglia distributed monitoring system: design, implementation, and experience\nYear: 2004\n\nAbstract: Ganglia is a scalable distributed monitoring system for high performance computing systems such as clusters and Grids. It is based on a hierarchical design targeted at federations of clusters. It relies on a multicast-based listen/announce protocol to monitor state within clusters and uses a tree of point-to-point connections amongst representative cluster nodes to federate clusters and aggregate their state. It leverages widely used technologies such as XML for data representation, XDR for compact, portable data transport, and RRDtool for data storage and visualization. It uses carefully engineered data structures and algorithms to achieve very low per-node overheads and high concurrency. The implementation is robust, has been ported to an extensive set of operating systems and processor architectures, and is currently in use on over 500 clusters around the world. This paper presents the design, implementation, and evaluation of Ganglia along with experience gained through real world deployments on systems of widely varying scale, configurations, and target application domains over the last two and a half years.","Title: NFS sensitivity to high performance networks\nYear: 1999\n\nAbstract: This paper examines NFS sensitivity to performance characteristics of emerging networks. We adopt an unusual method of inserting controlled delays into live systems to measure sensitivity to basic network parameters. We develop a simple queuing model of an NFS server and show that it reasonably characterizes our two live systems running the SPECsfs benchmark. Using the techniques in this work, we can infer the structure of servers from published SPEC results. Our results show that NFS servers are most sensitive to processor overhead; it can be the limiting factor with even a modest number of disks. Continued reductions in processor overhead will be necessary to realize performance gains from future multigigabit networks. NFS can tolerate network latency in the regime of newer LANs and IP switches. Due to NFS’s historic high mix of small metadata operations, NFS is quite insensitive to network bandwidth. Finally, we find that the protocol enhancements in NFS version 3 tolerate high latencies better than version 2 of the protocol.","Title: Towards modeling the performance of a fast connected components algorithm on parallel machines\nYear: 1995\n\nAbstract: We present and analyze a portable, high-performance algorithm for finding connected components on modern distributed memory multiprocessors. The algorithm is a hybrid of the classic DFS on the subgraph local to each processor and a variant of the Shiloach-Vishkin PRAM algorithm on the global collection of subgraphs. We implement the algorithm in Split-C and measure performance on the the Cray T3D, the Meiko CS-2, and the Thinking Machines CM-5 using a class of graphs derived from cluster dynamics methods in computational physics. On a 256 processor Cray T3D, the implementation outperforms all previous solutions by an order of magnitude. A characterization of graph parameters allows us to select graphs that highlight key performance features. We study the effects of these parameters and machine characteristics on the balance of time between the local and global phases of the algorithm and find that edge density, surface-to-volume ratio, and relative communication cost dominate performance. By understanding the effect of machine characteristics on performance, the study sheds light on the impact of improvements in computational and/or communication performance on this challenging problem.","Title: High-performance sorting on networks of workstations\nYear: 1997\n\nAbstract: We report the performance of NOW-Sort, a collection of sorting implementations on a Network of Workstations (NOW). We find that parallel sorting on a NOW is competitive to sorting on the large-scale SMPs that have traditionally held the performance records. On a 64-node cluster, we sort 6.0 GB in just under one minute, while a 32-node cluster finishes the Datamation benchmark in 2.41 seconds.Our implementations can be applied to a variety of disk, memory, and processor configurations; we highlight salient issues for tuning each component of the system. We evaluate the use of commodity operating systems and hardware for parallel sorting. We find existing OS primitives for memory management and file access adequate. Due to aggregate communication and disk bandwidth requirements, the bottleneck of our system is the workstation I/O bus.","Title: REXEC: A Decentralized, Secure Remote Execution Environment for Clusters\nYear: 2000\n\nAbstract: Bringing clusters of computers into the mainstream as general-purpose computing systems requires that better fa- cilities for transparent remote execution of parallel and se- quential applications be developed. While much research has been done in this area, most of this work remains inaccessible for clusters built using contemporary hardware and operating systems. Implementations are either too old and/or not pub- licly available, require use of operating systems which are not supported by modern hardware, or simply do not meet the functional requirements demanded by practical use in re- al world settings. To address these issues, we designed REX- EC, a decentralized, secure remote execution facility. It pro- vides high availability, scalability, transparent remote execu- tion, dynamic cluster configuration, decoupled node discov- ery and selection, a well-defined failure and cleanup model, parallel and distributed program support, and strong authen- tication and encryption. The system is implemented and is currently installed and in use on a 32-node cluster of 2-way SMPs running the Linux 2.2.5 operating system.","Title: Connecting low-power and lossy networks to the internet.\nYear: 2011\n\nAbstract: Many applications, ranging from wireless healthcare to energy metering on the smart grid, have emerged from a decade of research in wireless sensor networks. However, the lack of an IP-based network architecture precluded sensor networks from interoperating with the Internet, limiting their real-world impact. Given this disconnect, the IETF chartered the 6LoWPAN and RoLL working groups to specify ...","Title: IPv6 in Low-Power Wireless Networks.\nYear: 2010\n\nAbstract: With deeply embedded wireless sensors, a new tier of the Internet is emerging that will extend into the physical world. These wireless sensor nodes are expected to vastly outnumber conventional computer hosts as we see them today, but their strict resource constraints are unlike other technologies already common to the Internet. As wireless sensor network research took off, many in the field esche...","Title: An information-centric energy infrastructure: The Berkeley view\nYear: 2011\n\nAbstract: We describe an approach for how to design an essentially more scalable, flexible and resilient electric power infrastructure – one that encourages efficient use, integrates local generation, and manages demand through omnipresent awareness of energy availability and use over time. We are inspired by how the Internet has revolutionized communications infrastructure, by pushing intelligence to the edges while hiding the diversity of underlying technologies through well-defined interfaces. Any end device is a traffic source or sink and intelligent endpoints adapt their traffic to what the infrastructure can support. Our challenge is to understand how these principles can be suitably applied in formulating a new information-centric energy network for the 21st Century. We believe that an information-centric approach can achieve significant efficiencies in how electrical energy is distributed and used. The existing Grid assumes energy is cheap and information about its generation, distribution and use is expensive. Looking forward, energy will be dear, but pervasive information will allow us to use it more effectively, by agilely dispatching it to where it is needed, integrating intermittent renewable sources and intelligently adapting loads to match the available energy.","Title: SPINS: security protocols for sensor networks\nYear: 2002\n\nAbstract: As sensor networks edge closer towards wide-spread deployment, security issues become a central concern. So far, much research has focused on making sensor networks feasible and useful, and has not concentrated on security.We present a suite of security building blocks optimized for resource-constrained environments and wireless communication. SPINS has two secure building blocks: SNEP and &mgr;TESLA SNEP provides the following important baseline security primitives: Data confidentiality, two-party data authentication, and data freshness. A particularly hard problem is to provide efficient broadcast authentication, which is an important mechanism for sensor networks. &mgr;TESLA is a new protocol which provides authenticated broadcast for severely resource-constrained environments. We implemented the above protocols, and show that they are practical even on minimal hardware: the performance of the protocol suite easily matches the data rate of our network. Additionally, we demonstrate that the suite can be used for building higher level protocols.","Title: Securing the deluge Network programming system\nYear: 2006\n\nAbstract: A number of multi-hop, wireless, network programming systems have emerged for sensor network retasking but none of these systems support a cryptographically-strong, public-key-based system for source authentication and integrity verification. The traditional technique for authenticating a program binary, namely a digital signature of the program hash, is poorly suited to resource-contrained sensor nodes. Our solution to the secure programming problem leverages authenticated streams, is consistent with the limited resources of a typical sensor node, and can be used to secure existing network programming systems. Under our scheme, a program binary consists of several code and data segments that are mapped to a series of messages for transmission over the network. An advertisement, consisting of the program name, version number, and a hash of the very first message, is digitally signed and transmitted first. The advertisement authenticates the first message, which in turn contains a hash of the second message. Similarly, the second message contains a hash of the third message, and so on, binding each message to the one logically preceding it in the series through the hash chain. We augmented the Deluge network programming system with our protocol and evaluated the resulting system performance.","Title: BUSICO 3D: building simulation and control in unity 3D\nYear: 2014\n\nAbstract: In this demonstration, we present a novel system of building control and simulation focused on the integration of the physical and virtual worlds. Actuations and schedules can be manifested either in a physical space or in a virtualization of that space, allowing for more natural interactions with simulations and easier transferring of schedules and configurations from the simulated virtual environment to a real-world deployment. We provide an implementation using a widely used game engine (Unity 3D) and sMAP (Simple Measurement and Actuation Profile), a developed time series database and metadata store.","Title: A networked embedded system platform for the post-mote era\nYear: 2014\n\nAbstract: For the last fifteen years, research explored the hardware, software, sensing, communication abstractions, languages, and protocols that could make networks of small, embedded devices---motes---sample and report data for long periods of time unattended. Today, the application and technological landscapes have shifted, introducing new requirements and new capabilities. Hardware has evolved past 8 and 16 bit microcontrollers: there are now 32 bit processors with lower energy budgets and greater computing capability. New wireless link layers have emerged, creating protocols that support rapid and efficient setup and teardown but introduce novel limitations that systems must consider. The time has come to look beyond optimizing networks of motes. We look towards new technologies such as Bluetooth Low Energy, Cortex M processors, and capable energy harvesting, with new application spaces such as personal area networks, and new capabilities and requirements in security and privacy to inform contemporary hardware and software platforms. It is time for a new, open experimental platform in this post-mote era.","Title: Mica: a wireless platform for deeply embedded networks\nYear: 2002\n\nAbstract: Low-power integration of sensing, communication, and computation requires a new approach to wireless design. Flexible interfaces and primitive accelerators enable aggressive system-level optimizations. Mica's flexible design serves as a building block for creating efficient application-specific protocols. Instead of defining narrow, standardized application interfaces, Mica provides a set of richly interconnected primitives (such as data serializers and timing extractors) to facilitate cross-layer optimizations. To explore novel systems approaches, researchers can develop customized protocols tailored to their application; Mica does not require use of predefined protocols.","Title: A case for NOW (Networks of Workstations)\nYear: 1995\n\nAbstract: In this paper, we argue that because of recent technology advances, networks of workstations (NOWs) are poised to become the primary computing infrastructure for science and engineering, from low end interactive computing to demanding sequential and parallel applications. We identify three opportunities for NOWs that will benefit end- users: dramatically improving virtual memory and file system performance by using the aggregate DRAM of a NOW as a giant cache for disk; achieving cheap, highly available, and scalable file storage by using redundant arrays of workstation disks, using the LAN as the I/O backplane; and finally, multiple CPUs for parallel computing. We describe the technical challenges in exploiting these opportunities - namely, efficient communication hardware and software, global coordination of multiple workstation operating systems, and enterprise-scale network file systems. We are currently building a 100-node NOW prototype to demonstrate that practical solutions exist to these technical challenges.","Title: Fast parallel sorting under LogP: experience with the CM-5\nYear: 1996\n\nAbstract: In this paper, we analyze four parallel sorting algorithms (bitonic, column, radix, and sample sort) with the LogP model. LogP characterizes the performance of modern parallel machines with a small set of parameters: the communication latency (L), overhead (o), bandwidth (g), and the number of processors (P). We develop implementations of these algorithms in Split-C, a parallel extension to C, and compare the performance predicted by LogP to actual performance on a CM-5 of 32 to 512 processors for a range of problem sizes. We evaluate the robustness of the algorithms by varying the distribution and ordering of the key values. We also briefly examine the sensitivity of the algorithms to the communication parameters. We show that the LogP model is a valuable guide in the development of parallel algorithms and a good predictor of implementation performance. The model encourages the use of data layouts which minimize communication and balanced communication schedules which avoid contention. With an empirical model of local processor performance, LogP predictions closely match observed execution times on uniformly distributed keys across a broad range of problem and machine sizes. We find that communication performance is oblivious to the distribution of the key values, whereas the local processor performance is not; some communication phases are sensitive to the ordering of keys due to contention. Finally, our analysis shows that overhead is the most critical communication parameter in the sorting algorithms","Title: Benchmarking message passing performance using MPI\nYear: 1996\n\nAbstract: This paper describes a set of microbenchmarks for measuring the performance characteristics of MPI implementations. We explain the rationale behind the benchmarks and present the benchmark results on the Intel Paragon, IBM SP2, and SGI Power Challenge. Our measurements reveal how the hardware architecture and the underlying MPI implementation affect the message passing performance on the three platforms","Title: Virtual network transport protocols for Myrinet\nYear: 1998\n\nAbstract: Bringing direct and protected network multiprogramming into mainstream cluster computing requires innovations in three key areas: application programming interfaces, network virtualization systems, and lightweight communication protocols for high-speed interconnects. The AM-II API extends traditional active messages with support for client-server computing and facilitates the construction of parallel clients and distributed servers. Our virtual network segment driver enables a large number of arbitrary sequential and parallel applications to access network interface resources directly in a concurrent but fully protected manner. The NIC-to-NIC communication protocols provide reliable and at-most-once message delivery between communication endpoints. The NIC-to-NIC protocols perform well as the number of endpoints and the number of hosts in the cluster are scaled. The flexibility afforded by the underlying protocols enables a diverse set of timely research efforts. Other Berkeley researchers are actively using this system to investigate implicit techniques for the coscheduling of communicating processes, an essential part of high-performance communications in multiprogrammed clusters of uni- and multiprocessor servers. Other researchers are extending the active message protocols described here for clusters of symmetric multiprocessors, using so-called multiprotocol techniques and multiple network interfaces per machine","Title: Distributed Computation in the Physical World\nYear: 2005\n\nAbstract: Summary form only given. Networks of intelligent sensors that are distributed through the physical world will revolutionize practices in the life sciences, civil engineering, manufacturing, security, agriculture, ubiquitous computing, and many other areas. They also present an opportunity and a need to explore distributed algorithms that are wedded to the noisy, localized, time varying physical world. Bandwidth, storage, and energy limitations make in-network processing essential - within the node and among collections of nodes. The algorithms should be resource efficient, but also deal with noise, uncertainty and dynamically changing connectivity. A broad research community has been exploring these issues in the context of TinyOS and the Berkeley motes. This talk will highlight novel distributed algorithms coming out of these efforts and discuss issues in making such networks robust and programmable","Title: Extending IP to Low-Power, Wireless Personal Area Networks\nYear: 2008\n\nAbstract: Extending IP to low-power, wireless personal area networks (LoWPANs) was once considered impractical because these networks are highly constrained and must operate unattended for multiyear lifetimes on modest batteries. Many vendors embraced proprietary protocols, assuming that IP was too resource-intensive to be scaled down to operate on the microcontrollers and low-power wireless links used in LoWPAN settings. However, 6LoWPAN radically alters the calculation by introducing an adaptation layer that enables efficient IPv6 communication over IEEE 802.15.4 LoWPAN links.","Title: Keynote 2: Pervasive communication and interaction to make the built environment better and more sustainable\nYear: 2013\n\nAbstract: Over the past 15 years we have created a robust base of embedded networking technology to enable the `macroscope' - the ability to observe complex interactions of physical systems over a substantial extent of space and time. Created to understand the ecophysiology of natural systems, this technology is finding many natural applications in the quest to improve the sustainability of the built environment. In this talk we explore the role of pervasive computing and communications in buildings - where, in the US, we spend 90% of our time, over 70% of our electrical energy, and nearly 50% of our GHG emissions. We examine how pervasive monitoring serves to identify waste and opportunities for energy efficiency; how diverse sources of physical information can be homogenized to enable an innovative application ecosystem; and how a building operating system and services can provide a foundation for advanced control techniques that operate in concert with external factors, such as energy availability and weather, and for personalized environmental conditioning. To be quaint, ”there's a building app for that\".","Title: Classification of sidewalks in street view images\nYear: 2013\n\nAbstract: Mapping sidewalks in urban environments is key in the creation of pedestrian-friendly, sustainable cities. Currently, urban planners are hindered by a lack of information available in a format suitable for the large-scale analysis of sidewalk design. To demonstrate the impact that information technology could have in this area, we leverage techniques from machine learning and computer vision to gather information about the presence and quality of sidewalks in map images. In particular, we identify sidewalk segments in street view images using a random forest classifier, utilizing a set of local and global features that include geometric context, presence of lanes, pixel color, and location. Our results illustrate that this approach is effective in classifying sidewalk segments in a large set of street view images. This algorithm can be easily extended to other datasets, and can be automated to gather complete, fine-grained details about sidewalks for arbitrarily large urban environments.","Title: Enabling advanced environmental conditioning with a building application stack\nYear: 2013\n\nAbstract: There is enormous potential for building-focused applications to improve operation and sustainability, both for classical uses like modeling or fault detection as well as innovative ones like occupant-driven control or grid-aware energy management. We show that a building application stack - that addresses shortcomings of existing antiquated architectures by democratizing sensor data, constructing a framework for reliable and fault-tolerant operation of concurrent applications, and establishing an application programming interface to promote portability throughout the building stock - enables development of advanced applications. We observe the growing importance of applications that integrate sensors and actuators from the building infrastructure with those from “add-on” networks, and show how this design pattern is further empowered by the architecture. To prove the efficacy of the approach, we implement two advanced environmental conditioning applications on a large, commercial building that was not designed for either of them: a demand-controlled ventilation (DCV) system for balancing air quality considerations and energy use in conference and class room settings and a demand-controlled filtration (DCF) system for conserving recirculating fan energy in an intermittently occupied cleanroom setting. The DCV application is able to reduce air quality threshold violations by over 95% and concurrently reduce ventilation energy consumption by over 80%, while the DCF application can reduce recirculating fan power consumption by half with no repercussions on air quality when the room is occupied. Further, the portability of these applications highlights the potential of the architecture to enable widespread and rapid application development throughout the building stock.","Title: A comparative study of high renewables penetration electricity grids\nYear: 2013\n\nAbstract: Electricity grids are transforming as renewables proliferate, yet operational concerns due to fluctuations in renewables sources could limit the ultimate potential for high penetrations of renewables. In this paper, we compare three electricity grids - California, Germany, and Ontario - studying the effects of relative cost of solar and wind generation on the selection of the renewables mix, and examine the resulting excess generation. We then observe the effects of the renewables mix and the use of baseload energy generation on the limits to renewables penetration, quantifying what proportion of delivered energy can be provided by renewables. Our study shows that the optimal renewables mix, from the perspective of minimizing total cost of generation, is highly dependent on the relative costs of technology, and that above a certain penetration rate, different for each grid, the optimal mix must contain both solar and wind generation.","Title: E-mission: Automated transportation emission calculation using smartphones\nYear: 2015\n\nAbstract: Tracking travel patterns and modes is useful on many levels. Prior efforts to collect this information have been stymied by low accuracies or reliance on supplementary devices. One technique to overcome low accuracies is to use prompted recall, in which the user is prompted to supply the ground truth for automatically generated information. However, prompted recall increases the burden on the user, which could lead to low adoption or high drop out rates. Using techniques from behavioral economics, and prompting directly on the smartphone can reduce user burden, and also increase engagement for ongoing data collection. In this paper, we describe a system that improves accuracy by using behavioral techniques for prompted recall on the smartphone, and aggregates the information to help detect large scale patterns. We also present the evaluation of a prototype implementation that was used to collect data from 44 unpaid volunteers in the San Francisco Bay Area over 3 months and compute their transportation carbon footprint.","Title: DISTIL: Design and implementation of a scalable synchrophasor data processing system\nYear: 2015\n\nAbstract: The introduction and deployment of cheap, high precision, high-sample-rate next-generation synchrophasors en masse in both the transmission and distribution tier - while invaluable for event diagnosis, situational awareness and capacity planning - poses a problem for existing methods of phasor data analysis and storage. Addressing this, we present the design and implementation of a novel architecture for synchrophasor data analysis on distributed commodity hardware. At the core is a new feature-rich timeseries store, BTrDB. Capable of sustained writes and reads in excess of 16 million points per second per cluster node, advanced query functionality and highly efficient storage, this database enables novel analysis and visualization techniques. Leveraging this, a distillate framework has been developed that enables agile development of scalable analysis pipelines with strict guarantees on result integrity despite asynchronous changes in data or out of order arrival. Finally, the system is evaluated in a pilot deployment, archiving more than 216 billion raw datapoints and 515 billion derived datapoints from 13 devices in just 3.9TB. We show that the system is capable of scaling to handle complex analytics and storage for tens of thousands of next-generation synchrophasors on off-the-shelf servers.","Title: Ownership is theft: experiences building an embedded OS in rust\nYear: 2015\n\nAbstract: Rust, a new systems programming language, provides compile-time memory safety checks to help eliminate runtime bugs that manifest from improper memory management. This feature is advantageous for operating system development, and especially for embedded OS development, where recovery and debugging are particularly challenging. However, embedded platforms are highly event-based, and Rust's memory safety mechanisms largely presume threads. In our experience developing an operating system for embedded systems in Rust, we have found that Rust's ownership model prevents otherwise safe resource sharing common in the embedded domain, conflicts with the reality of hardware resources, and hinders using closures for programming asynchronously. We describe these experiences and how they relate to memory safety as well as illustrate our workarounds that preserve the safety guarantees to the largest extent possible. In addition, we draw from our experience to propose a new language extension to Rust that would enable it to provide better memory safety tools for event-driven platforms.","Title: BTrDB: Optimizing Storage System Design for Timeseries Processing.\nYear: 2016\n\nAbstract: The increase in high-precision, high-sample-rate telemetry timeseries poses a problem for existing timeseries databases which can neither cope with the throughput demands of these streams nor provide the necessary primitives for effective analysis of them. We present a novel abstraction for telemetry timeseries data and a data structure for providing this abstraction: a time-partitioning version-annotated copy-on-write tree. An implementation in Go is shown to outperform existing solutions, demonstrating a throughput of 53 million inserted values per second and 119 million queried values per second on a four-node cluster. The system achieves a 2.9× compression ratio and satisfies statistical queries spanning a year of data in under 200ms, as demonstrated on a year-long production deployment storing 2.1 trillion data points. The principles and design of this database are generally applicable to a large variety of timeseries types and represent a significant advance in the development of technology for the Internet of Things.","Title: Short Paper: A Method for Discovering Functional Relationships Between Air Handling Units and Variable-Air-Volume Boxes From Sensor Data.\nYear: 2015\n\nAbstract: In Building Automation Systems contextual information about sensors is frequently missing or hard-coded in the control code. Retrieving this data is time consuming and error-prone, but necessary to write any type of control application. Automating metadata acquisition is a new and active area of research. Methods to infer metadata from sensor labels or from recorded data have been previously proposed. However, these methods are ineffective in uncovering the association between HVAC components. In fact, measured variables (pressures, temperatures, flows, valve positions) have slow and attenuated responses to changes in input variables, thus impairing the efficacy of correlation methods. In addition, sensor readings are frequently constrained between physical limits and kept around setpoints by nested control loops. For this reason, pure statistical methods fail to capture the differences between sensor streams and are unable to classify them. In this article, we propose a new method for discovering functional relationships between Air Handling Units and Variable-Air-Volume Boxes from sensor data. The method utilizes perturbations of subsystem variables, while guaranteeing that the building zones remain within comfort boundaries. When applied to an existing building, our proposed method reveals correct associations in ~80% of the cases, and outperforms other methods.","Title: Automated Metadata Construction to Support Portable Building Applications\nYear: 2015\n\nAbstract: Commercial buildings consume nearly 19\\\\% of delivered energy in the U.S, nearly half (42%) of which is consumed in buildings with digital control systems comprised of wired sensor networks. These sensors have scant metadata, and are represented by ``tags'' which are obscure, building-specific and not machine parseable. We develop a human-in-the-loop synthesis technique which uses syntactic and data-driven steps to parse these sensor tags into a common namespace, which can enable portable building applications. We show that our technique allows an expert to fully parse a large fraction (~70%) of the tags with 24, 15 and 43 examples for three large commercial buildings comprising 1586, 2522 and 1865 sensors respectively, and deploy three portable applications on two buildings with less than 30 examples.","Title: Poster Abstract: XBOS: An Extensible Building Operating System.\nYear: 2015\n\nAbstract: We present XBOS, an eXtensible Building Operating System for integrated management of previously isolated building subsystems. The key contribution of XBOS is the Building Profile, a canonical, executable description of a building and its subsystems that changes with a building and evolves control processes and applications accordingly. The design and implementation of XBOS addresses the six dimensions of an effective BAS -- hardware presentation layer, canonical metadata, control process management, building evolution management, security, scalable UX and API.","Title: Poster Abstract: Well-Connected Microzones for Increased Building Efficiency and Occupant Comfort.\nYear: 2015\n\nAbstract: Personal Comfort Systems (PCS) are capable of maintaining occupant comfort in buildings despite large deviations from recommended \\\"comfortable\\\" temperatures. We present a novel digital controller for a well-studied (previously analog) PCS, allowing it to report real-time telemetry and respond to programmatic actuation requests. This enables the established capabilities of a PCS to be synergistically combined with occupant-aware building applications, providing new methods of comfort and energy efficiency maximization.","Title: BearLoc: A Composable Distributed Framework for Indoor Localization Systems\nYear: 2015\n\nAbstract: Many indoor localization algorithms have been proposed to enable location-based applications in indoor environments. However, these systems are monolithic and not component-based. We present BearLoc, a distributed modular framework for indoor localization systems that provides (1) natural development abstractions for sensor, algorithm, and application components, and (2) easy and flexible component composition. We demonstrate the merits of BearLoc with an example use case. Our evaluation shows we can reduce developer lines of code by 60% while introducing acceptable network delay overhead.","Title: System Design for a Synergistic, Low Power Mote/BLE Embedded Platform.\nYear: 2016\n\nAbstract: Modern IoT prototyping platforms fall short in terms of energy efficiency, connectivity and software programming practices. We present the design of a new hardware and software platform that addresses these shortcomings by bringing together Mobile, Wearable, Maker and Wireless Sensor Network technologies to enable rapid prototyping with a high degree of synergy and energy efficiency. This is achieved in part by leveraging the Memory Protection Unit on modern microcontrollers along with a novel syscall interface to provide kernel / user isolation and a clean concurrency model. Such a design allows a wide range of languages to be used for application development without significant adaptation. We demonstrate how careful choice of application language allows the naturally asynchronous nature of embedded programming to be expressed cleanly and powerfully. Finally we evaluate the platform in several integrated use cases, providing examples of the capabilities introduced by Synergy.","Title: Enabling Synergy in IoT: Platform to Service and Beyond\nYear: 2017\n\nAbstract: To enable a prosperous Internet of Things, devices and services must be extensible and adapt to changes in the environment or user interaction patterns. These requirements manifest as a set of design principles for each of the layers in an IoT ecosystem, from hardware to cloud services. This paper gives concrete guidelines learned from building a full-stack Synergistic IoT platform.","Title: The Once And Future Internet Of Everything.\nYear: 2016\n\nAbstract: I am often asked these days, \\\"Is IoT really as transformative as all the buzz suggests, or is it a lot of hype?\\\" My answer is simply, \\\"Yes.\\\" And the road to here has been a fascinating interplay of academic research accomplishments, industry advances (often with other drivers), and standardization processes (for lack of a better term). It was predictable that today we would be poised for the \\\"next tier\\\" of the Internet to take off, but the endgame seems to be even messier than expected.","Title: Optimizing The Diamond Lane: A More Tractable Carpool Problem And Algorithms\nYear: 2016\n\nAbstract: Carpooling has been long deemed a promising approach to better utilizing existing transportation infrastructure. However, there are several reasons carpooling is still not the preferred mode of commute in the United States: first, complex human factors, including time constraints and not having right incentive structures, discourage the sharing of rides; second, algorithmic and technical barriers inhibit the development of online services for matching riders. In this work, we study algorithms for 3+ high-occupancy vehicle (HOV) lanes, which permit vehicles that hold three or more people. We focus on the technical barriers but also address the aforementioned human factors. We formulate the HOV3 Carpool problem, and show that it is NP-Complete. We thus pose the relaxed problem HOV3-Carpool problem, allowing groups of up to size three, and propose several methods for solving the problem of finding globally optimal carpool groups that may utilize these 3-HOV lanes. Our methods include local search, integer programming, and dynamic programming. Our local search methods include sampling-based (hill-climbing and simulated annealing), classical neighborhood search, and a hybrid random neighborhood search. We assess the methods numerically in terms of objective value and scalability. Our findings show that our sampling-based local search methods scale up to 100K agents, thereby improving upon related previous work (which studies up to 1000 agents). The hill climbing local search method converges significantly closer and faster towards a naive lower bound on cumulative carpooling cost.","Title: Challenging the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL): A Survey.\nYear: 2017\n\nAbstract: RPL is the IPv6 routing protocol for low-power and lossy networks, standardized by IETF in 2012 as RFC6550. Specifically, RPL is designed to be a simple and inter-operable networking protocol for resource-constrained devices in industrial, home, and urban environments, intended to support the vision of the Internet of Things with thousands of devices interconnected through multihop mesh networks. ...","Title: Do Not Lose Bandwidth: Adaptive Transmission Power and Multihop Topology Control.\nYear: 2017\n\nAbstract: We show that a multihop wireless network can achieve better bandwidth and routing stability when transmission power and routing topology are jointly and adaptively controlled. Our experiments show that the predominant u0027fixed and uniformu0027 transmission power strategy with u0027link quality and hop distanceu0027-based routing topology construction loses significant bandwidth due to hidden terminal and load imbalance problems. We design an adaptive and distributed control mechanism for transmission power and routing topology, PCRPL, within the standard RPL routing protocol. We implement PC-RPL on real embedded devices and evaluate its performance on a 49-node multihop testbed. PC-RPL reduces total end-to-end packet losses ~7-fold without increasing hop distance compared to RPL with the highest transmission power, resulting in 17% improvement in aggregate bandwidth and 64% for the worst-case node.","Title: HodDB: a query processor for brick\nYear: 2017\n\nAbstract: Brick [1] is a recent effort to design a metadata schema for describing building components, subsystems and the relationships between them. With growing interest in Brick, it is important to characterize how suitable Brick is for embedding in real building applications. This demonstration will present HodDB [3], a new database and query processor for Brick models. Attendees will use HodDB to query and explore real Brick models using a variety of textual and graphical query interfaces, and see how HodDB can embed Brick queries in real applications.","Title: Hamilton: a cost-effective, low power networked sensor for indoor environment monitoring\nYear: 2017\n\nAbstract: Operating buildings can be challenging, especially with poor instrumentation of the indoor environment. There are several wireless sensor platforms on the market but most are too difficult to deploy en-masse, requiring the end-user to program devices, or manage infrastructure. Many rely on smart-phones and do not work when unattended. The Hamilton wireless sensor node is a full-stack solution providing a low-cost and low-power high-resolution sensor that operates for more than five years on a battery, along with all the cloud infrastructure required to interact with the data. It is pre-programmed and ready to use, but the firmware can be easily modified by using the standard C language.","Title: Democratizing authority in the built environment.\nYear: 2018\n\nAbstract: Operating systems and applications in the built environment have relied upon central authorization and management mechanisms that restrict their scalability, especially with respect to administrative overhead. We propose a new set of primitives encompassing syndication, security, and service execution that unifies the management of applications and services across the built environment, while enabling participants to individually delegate privilege across multiple administrative domains with no loss of security or manageability. We show how to leverage a decentralized authorization syndication platform to extend the design of building operating systems beyond the single administrative domain of a building. The authorization system leveraged is based on blockchain smart contracts to permit decentralized and democratized delegation of authorization without central trust. Upon this, a publish/subscribe syndication tier and a containerized service execution environment are constructed. Combined, these mechanisms solve problems of delegation, federation, device protection and service execution that arise throughout the built environment. We leverage a high-fidelity city-scale emulation to verify the scalability of the authorization tier, and briefly describe a prototypical democratized operating system for the built environment using this foundation.\n\nThis is an extension of work presented in Ref. [3].","Title: System Architecture Directions for Post-SoC/32-bit Networked Sensors.\nYear: 2018\n\nAbstract: The emergence of low-power 32-bit Systems-on-Chip (SoCs), which integrate a 32-bit MCU, radio, and flash, presents an opportunity to re-examine design points and trade-offs at all levels of the system architecture of networked sensors. To this end, we develop a post-SoC/32-bit design point called Hamilton, showing that using integrated components enables a ~$7 core and shifts hardware modularity to design time. We study the interaction between hardware and embedded operating systems, identifying that (1) post-SoC motes provide lower idle current (5.9 μA) than traditional 16-bit motes, (2) 32-bit MCUs are a major energy consumer (e.g., tick increases idle current >50 times), comparable to radios, and (3) thread-based concurrency is viable, requiring only 8.3 μs of context switch time. We design a system architecture, based on a tickless multithreading operating system, with cooperative/adaptive clocking, advanced sensor abstraction, and preemptive packet processing. Its efficient MCU control improves concurrency with ~30% less energy consumption. Together, these developments set the system architecture for networked sensors in a new direction.","Title: Bringing Full-Scale TCP to Low-Power Networks.\nYear: 2018\n\nAbstract: Although TCP has widespread adoption in the Internet, wireless sensor networks (WSNs) generally use simpler UDP-based protocols. The few existing TCP implementations for sensor network operating systems do not support all of the features of TCP. We present a full-scale TCP implementation for sensor networks, called TCPlp, based on the TCP protocol logic of the FreeBSD Operating System. Our implementation demonstrates that full-scale TCP can run within the resource constraints of a modern WSN platform, and serves as a vehicle to explore the benefits of using a full TCP stack in the WSN setting. We showcase TCPlp via three applications of TCP: (1) reliable data collection in the context of an application, (2) an interactive configuration/debug shell, and (3) a mote-based web server.","Title: MARVEL: Enabling Mobile Augmented Reality with Low Energy and Low Latency.\nYear: 2018\n\nAbstract: This paper presents MARVEL, a mobile augmented reality (MAR) system which provides a notation display service with imperceptible latency (<100 ms) and low energy consumption on regular mobile devices. In contrast to conventional MAR systems, which recognize objects using image-based computations performed in the cloud, MARVEL mainly utilizes a mobile device's local inertial sensors for recognizing and tracking multiple objects, while computing local optical flow and offloading images only when necessary. We propose a system architecture which uses local inertial tracking, local optical flow, and visual tracking in the cloud synergistically. On top of that, we investigate how to minimize the overhead for image computation and offloading. We have implemented and deployed a holistic prototype system in a commercial building and evaluate MARVEL's performance. The efficient use of a mobile device's capabilities lowers latency and energy consumption without sacrificing accuracy.","Title: Mortar: an open testbed for portable building analytics.\nYear: 2018\n\nAbstract: Access to large amounts of real-world data has long been a barrier to the development and evaluation of analytics applications for the built environment. Open data sets exist, but they are limited in their span (how much data is available) and context (what kind of data is available and how it is described). Evaluation of such analytics is also limited by how the analytics themselves are implemented, often using hard-coded names of building components, points and locations, or unique input data formats.\n\nTo advance the methodology for how such analytics are implemented and evaluated, we present Mortar: an open testbed for portable building analytics, currently spanning 90 buildings and containing over 9.1 billion data points. All buildings in the testbed are described using Brick, a recently developed metadata schema, providing rich functional descriptions of building assets and subsystems. We also propose a simple architecture for writing portable analytics applications that are robust to the diversity of buildings and can configure themselves based on context. We demonstrate the utility of Mortar by implementing 11 applications from the literature.","Title: TCPlp: System Design and Analysis of Full-Scale TCP in Low-Power Networks.\nYear: 2018\n\nAbstract: Low power and lossy networks (LLNs) enable diverse applications integrating many embedded devices, often requiring interconnectivity between LLNs and existing TCP/IP networks. However, the sensor network community has been reluctant to adopt TCP, providing only highly simplified TCP implementations on sensor platforms and, instead, developing LLN-specific protocols to provide connectivity. We present a full-scale TCP implementation, based on the TCP protocol logic in FreeBSD, capable of operating over IEEE 802.15.4 within the memory constraints of Cortex-M0+ based platforms. We systematically investigate the behavior of a full-featured TCP implementation in the LLN setting. It provides a 5x to 40x improvement in throughput compared to prior studies. Moreover, we find that TCP is more robust in LLNs than studies of TCP over traditional WLANs would suggest. We empirically demonstrate that, in a lossy environment typical of LLNs, TCP can achieve power consumption comparable to CoAP, a representative LLN-specific reliability protocol. We discuss the potential role of TCP in sensor networks, observing that gateway-free, retransmission-based reliable transport would be an asset to sensor network applications. We conclude that TCP should have a place in the LLN architecture moving forward.","Title: A composable framework for secure multi-modal access to internet services from Post-PC devices\nYear: 2000\n\nAbstract: The Post-PC revolution is bringing information access to a wide range of devices beyond the desktop, such as public kiosks, and mobile devices like cellular telephones, PDAs, and voice based vehicle telematics. However, existing deployed Internet services are geared toward the secure rich interface of private desktop computers. We propose the use of an infrastructure-based secure proxy architecture to bridge the gap between the capabilities of Post-PC devices and the requirements of Internet services. By combining generic content and security transformation functions with service-specific rules, the architecture decouples device capabilities from service requirements and simplifies the addition of new devices and services. Security and protocol specifics are abstracted into reusable components. Additionally, the architecture offers the novel ability to deal with untrusted public Internet access points by providing fine-grain control over the content and functionality exposed to the end device, as well as support for using trusted and untrusted devices in tandem. Adding support for a deployed Internet service requires a few hundred lines of scraping scripts. Similarly, adding support for a new device requires a few hundred lines of stylesheets for the device format. The average latency added by proxy transformations is around three seconds in our unoptimized Java implementation.","Title: Design and analysis of a query processor for brick.\nYear: 2018\n\nAbstract: Brick is a recently proposed metadata schema and ontology for describing building components and the relationships between them. It represents buildings as directed labeled graphs using the RDF data model. Using the SPARQL query language, building-agnostic applications query a Brick graph to discover the set of resources and relationships they require to operate. Latency-sensitive applications, such as user interfaces, demand response, and model-predictive control, require fast queries—conventionally less than 100ms.\n\nWe benchmark a set of popular open source and commercial SPARQL databases against three real Brick models using seven application queries and find that none of them meet this performance target. This lack of performance can be attributed to design decisions that optimize for queries over large graphs consisting of billions of triples but give poor spatial locality and join performance on the small dense graphs typical of Brick. We present the design and evaluation of HodDB, a RDF/SPARQL database for Brick built over a node-based index structure. HodDB performs Brick queries 3--700× faster than leading SPARQL databases and consistently meets the 100ms threshold, enabling the portability of important latency-sensitive building applications.\n\nThis article is an extension of a previously published work [16].","Title: Jedi: Many-To-Many End-To-End Encryption And Key Delegation For Iot\nYear: 2019\n\nAbstract: As the Internet of Things (IoT) emerges over the next decade, developing secure communication for IoT devices is of paramount importance. Achieving end-to-end encryption for large-scale IoT systems, like smart buildings or smart cities, is challenging because multiple principals typically interact indirectly via intermediaries, meaning that the recipient of a message is not known in advance. This paper proposes JEDI (Joining Encryption and Delegation for IoT), a many-to-many end-to-end encryption protocol for IoT. JEDI encrypts and signs messages end-to-end, while conforming to the decoupled communication model typical of IoT systems. JEDI's keys support expiry and fine-grained access to data, common in IoT. Furthermore, JEDI allows principals to delegate their keys, restricted in expiry or scope, to other principals, thereby granting access to data and managing access control in a scalable, distributed way. Through careful protocol design and implementation, JEDI can run across the spectrum of IoT devices, including ultra low-power deeply embedded sensors severely constrained in CPU, memory, and energy consumption. We apply JEDI to an existing IoT messaging system and demonstrate that its overhead is modest.","Title: Thread/OpenThread: A Compromise in Low-Power Wireless Multihop Network Architecture for the Internet of Things\nYear: 2019\n\nAbstract: Extending an Internet subnet by connecting resource-constrained nodes (e.g., embedded sensors and actuators) over multiple wireless hops is necessary to support the future Internet of Things (IoT). RPL, the IPv6 routing standard for low-power and lossy networks, tried to achieve this goal but has not seen wide adoption in practice. As an alternative, Thread is a recently standardized low-power network protocol for IoT, driven by the Thread group, an industry consortium led by Google/Nest. We provide a comparative analysis of the technical aspects of RPL and Thread based on their specifications, explaining why using Thread, as opposed to RPL, may make sense for the future Internet. Specifically, the fundamental differences between RPL and Thread are their respective scopes and multihop network architectures, which result in Thread's unique design and advantages over RPL. Lastly, we evaluate Thread in an indoor multihop wireless testbed using OpenThread, an official open source implementation of Thread. This work serves as the first analysis of the Thread protocol in academia.","Title: Mage: Nearly Zero-Cost Virtual Memory For Secure Computation\nYear: 2021\n\nAbstract: Secure Computation (SC) is a family of cryptographic primitives for computing on encrypted data in single-party and multi-party settings. SC is being increasingly adopted by industry for a variety of applications. A significant obstacle to using SC for practical applications is the memory overhead of the underlying cryptography. We develop MAGE, an execution engine for SC that efficiently runs SC computations that do not fit in memory. We observe that, due to their intended security guarantees, SC schemes are inherently oblivioustheir memory access patterns are independent of the input data. Using this property, MAGE calculates the memory access pattern ahead of time and uses it to produce a memory management plan. This formulation of memory management, which we call memory programming, is a generalization of paging that allows MAGE to provide a highly efficient virtual memory abstraction for SC. MAGE outperforms the OS virtual memory system by up to an order of magnitude, and in many cases, runs SC computations that do not fit in memory at nearly the same speed as if the underlying machines had unbounded physical memory to fit the entire computation."],"string":"[\n \"Title: TAM—a compiler controlled threaded abstract machine\\nYear: 1993\\n\\nAbstract: The Threaded Abstract Machine (TAM) refines dataflow execution models to address the critical constraints that modern parallel architectures place on th e compilation of general-purpose parallel programming languages. TAM defines a self-scheduled machine language ofparallel threads, which provides a path from dataflow- graph program representations to conventional control flow . The most important feature of TAM is the way it exposes the interaction between the handling of asynchronous message events, the scheduling of computation, and the utilizati on of the storage hierarchy. This paper provides a complete description of TAM and codifies the model in terms of a pseudo machine language TL0. Issues in compilation from a high level parallel language to TL0 are discussed in general and specifically in regard to the Id90 language. The implementation of TL0 on the CM-5 multiprocessor is explained in detail. Using this implementation, a cost model is developed for the various TAM primitives. The TAM approach is evaluated on sizable Id90 programs on a 64 processor system. The scheduling hierarchy of quanta and threads is shown to provide substantial locality while tolerating long latencies. Thi s allows the average thread scheduling cost to be extremely l ow.\",\n \"Title: Active Sensor Networks\\nYear: 2005\\n\\nAbstract: We propose using application specific virtual machines (ASVMs) to reprogram deployed wireless sensor networks. ASVMs provide a way for a user to define an application- specific boundary between virtual code and the VM en- gine. This allows programs to be very concise (tens to hundreds of bytes), making program installation fast and inexpensive. Additionally, concise programs interpret few instructions, imposing very little interpretation over- head. We evaluate ASVMs against current proposals for network programming runtimes and show that ASVMs are more energy efficient by as much as 20%. We also evaluate ASVMs against hand built TinyOS applications and show that while interpretation imposes a significant execution overhead, the low duty cycles of realistic ap- plications make the actual cost effectively unmeasurable.\",\n \"Title: The firecracker protocol\\nYear: 2004\\n\\nAbstract: We propose the Firecracker protocol for data dissemi- nation in wireless sensor networks. Firecracker uses a combination of routing and broadcasts to rapidly deliver a piece of data to every node in a network. To start dis- semination, the data source sends data to distant points in the network. Once the data reaches its destinations, broadcast-based dissemination begins along the paths, like a string of firecrackers. By using an initial routing phase, Firecracker can dis- seminate at a faster rate than scalable broadcasts while sending fewer packets. The selection of points to route to has a large effect on performance, indicating possible requirements for any-to-any routing protocols in wireless sensor networks.\",\n \"Title: Scheduling with implicit information in distributed systems\\nYear: 1998\\n\\nAbstract: Implicit coscheduling is a distributed algorithm for time-sharing communicating processes in a cluster of workstations. By observing and reacting to implicit information, local schedulers in the system make independent decisions that dynamically coordinate the scheduling of communicating processes. The principal mechanism involved is two-phase spin-blocking: a process waiting for a message response spins for some amount of time, and then relinquishes the processor if the response does not arrive.In this paper, we describe our experience implementing implicit coscheduling on a cluster of 16 UltraSPARC I workstations; this has led to contributions in three main areas. First, we more rigorously analyze the two-phase spin-block algorithm and show that spin time should be increased when a process is receiving messages. Second, we present performance measurements for a wide range of synthetic benchmarks and for seven Split-C parallel applications. Finally, we show how implicit coscheduling behaves under different job layouts and scaling, and discuss preliminary results for achieving fairness.\",\n \"Title: Design Of An Application-Cooperative Management System For Wireless Sensor Networks\\nYear: 2005\\n\\nAbstract: This paper argues for the usefulness of an application-cooperative interactive management system for wireless sensor networks, and presents SNMS, a Sensor Network Management System. SNMS is designed to be simple and have minimal impact on memory and network traffic, while remaining open and flexible. The system is evaluated in light of issues derived from real deployment experiences.\",\n \"Title: Assessing Fast Network Interfaces\\nYear: 1996\\n\\nAbstract: Assessing the performance of emerging high-speed networks is difficult. Our communication microbenchmark evaluates design changes in a communications system. Our microbenchmark generates a graphical signature from which we extract communication performance parameters for the hardware-software tandem. We use the LogP conceptual model for communication systems. (LogP stands for the parameters latency, overhead, gap, and processors). We study three important platforms that represent diverse points in the network interface design space: the Intel Paragon, Meiko CS-2, and a cluster of Sparcstation-20s connected by Myrinet switches using LANai SBus cards. Our study views each machine as a gray box supporting Active Messages and conforming to the LogP framework. We devise a simple set of communication microbenchmarks and measure the performance on each platform to obtain the LogP parameters\",\n \"Title: Modeling communication pipeline latency\\nYear: 1998\\n\\nAbstract: In this paper, we study how to minimize the latency of a message through a network that consists of a number of store-and-forward stages. This research is especially relevant for today's low overhead communication systems that employ dedicated processing elements for protocol processing. We develop an abstract pipeline model that reveals a crucial performance tradeoff involving the effects of the overhead of the bottleneck stage and the bandwidth of the remaining stages. We exploit this tradeoff to develop a suite of fragmentation algorithms designed to minimize message latency. We also provide an experimental methodology that enables the construction of customized pipeline algorithms that can adapt to the specific system characteristics and application workloads. By applying this methodology to the Myrinet-GAM system, we have improved its latency by up to 51%. Our theoretical framework is also applicable to pipelined systems beyond the context of high speed networks.\",\n \"Title: Wide Area Cluster Monitoring With Ganglia\\nYear: 2003\\n\\nAbstract: In this paper, we present a structure for monitoring a large set of computational clusters. We illustrate methods for scaling a monitor network comprised of many clusters while keeping processing requirements low. A design for presenting high-level web-based summaries of the monitor network is provided, along with a generalization to a distributed, multiple-resolution monitoring tree. Emphasis is placed on scalability, fast query response, fault tolerance, and grid compatibility. Experimental evidence is presented that demonstrates the performance of our design.\",\n \"Title: The explicit token store\\nYear: 1990\\n\\nAbstract: This paper presents an unusually simple approach to dynamic dataflow execution, called the Explicit Token Store (ETS) architecture, and its current realization in Monsoon. The essence of dynamic dataflow execution is captured by a simple transition on state bits associated with storage local to a processor. Low-level storage management is performed by the compiler in assigning nodes to slots in an activation frame, rather than dynamically in hardware. The processor is simple, highly pipelined, and quite general. There is exactly one instruction executed for each action on the dataflow graph. Thus, the machine-oriented ETS model provides new insight into the real cost of direct execution of dataflow graphs.\",\n \"Title: The Mantis parallel debugger\\nYear: 1996\\n\\nAbstract: Parallel tools often fail to integrate effectively with other parallel systems, exacerbating the inherent difficulty of programming a massively parallel machine. Successful parallel debugging requires the rethinking of traditional debugging goals in the context of parallelism. The following four objectives: rapid focus, scalability, economy of presentation, and portability, represent the more difficult aspects of parallel debugging. In light of these specific goals, this paper presents Mantis,...\",\n \"Title: Analysis of multithreaded microprocessors under multiprogramming\\nYear: 1992\\n\\nAbstract: We examine multithreading to improve uniprocessor cost/performance on multiple processes. Processor utilization and cache behavior are studied analytically and under simulation by interleaving reference traces to model timesharing and multithreading. Multithreading a small number of threads is superior with large on-chip caches and significant memory latency. The switch need not be extremely fast. Surprisingly, miss ratios under multithreading may be lower than under timesharing, because switch-on-miss multithreading favors processes with better cache behavior.\",\n \"Title: Searching for the sorting record: experiences in tuning NOW-Sort\\nYear: 1998\\n\\nAbstract: We present our experiences in developing and tuning the performanceof NOW-Sort, a parallel, disk-to-disk sorting algorithm.NOW-Sort currently holds two world records in databaseindustrystandard benchmarks. Critical to the tuning processwas the setting of expectations, which tell the programmer bothwhere to tune and when to stop. We found three categories ofuseful tools: tools that help set expectations and configurethe application to different hardware parameters, visualizationtools...\",\n \"Title: Effects of communication latency, overhead, and bandwidth in a cluster architecture\\nYear: 1997\\n\\nAbstract: This work provides a systematic study of the impact of communication performance on parallel applications in a high performance network of workstations. We develop an experimental system in which the communication latency, overhead, and bandwidth can be independently varied to observe the effects on a wide range of applications. Our results indicate that current efforts to improve cluster communication performance to that of tightly integrated parallel machines results in significantly improved application performance. We show that applications demonstrate strong sensitivity to overhead, slowing down by a factor of 60 on 32 processors when overhead is increased from 3 to 103 µs. Applications in this study are also sensitive to per-message bandwidth, but are surprisingly tolerant of increased latency and lower per-byte bandwidth. Finally, most applications demonstrate a highly linear dependence to both overhead and per-message bandwidth, indicating that further improvements in communication performance will continue to improve application performance.\",\n \"Title: An Analysis Of Vi Architecture Primitives In Support Of Parallel And Distributed Communication\\nYear: 2002\\n\\nAbstract: We present the results of a detailed study of the Virtual Interface (VI) paradigm as a communication foundation for a distributed computing environment. Using Active Messages and the Split-C global memory model, we analyze the inherent costs of using VI primitives to implement these high-level communication abstractions. We demonstrate a minimum mapping cost (i.e. the host processing required to map one abstraction to a lower abstraction) of 5.4 mus for both Active Messages and Split-C using four-way 550 MHz Pentium III SMPs and the Myrinet network. We break down this cost to the use of individual VI primitives in supporting flow control, buffer management and event processing and identify the completion queue as the source of the highest overhead. Bulk transfer performance plateaus at 44 Mbytes/s for both implementations are due to the addition of fragmentation requirements. Based on this analysis, we present the implications for the VI successor, Infiniband. Copyright (C) 2002 John Wiley Sons, Ltd.\",\n \"Title: A Network-Centric Approach to Embedded Software for Tiny Devices\\nYear: 2001\\n\\nAbstract: The ability to incorporate low-power, wireless communication into embedded devices gives rise to a newgenre of embedded software that is distributed, dynamic, and adaptive. This paper describes the network-centric approach to designing software for highly constrained devices embodied in TinyOS. It develops a tiny Active Message communication model and shows how it is used to build non-blocking applications and higher level networking capabilities, such as multihop ad hoc routing. It shows how the TinyOS event-driven approach is used to tackle challenges in implementing the communication model with very limited storage and the radio channel modulated directly in software in an energy efficient manner. The open, component-based design allows many novel relationships between system and application.\",\n \"Title: A blueprint for introducing disruptive technology into the Internet\\nYear: 2003\\n\\nAbstract: This paper argues that a new class of geographically distributed network services is emerging, and that the most effective way to design, evaluate, and deploy these services is by using an overlay-based testbed. Unlike conventional network testbeds, however, we advocate an approach that supports both researchers that want to develop new services, and clients that want to use them. This dual use, in turn, suggests four design principles that are not widely supported in existing testbeds: services should be able to run continuously and access a slice of the overlay's resources, control over resources should be distributed, overlay management services should be unbundled and run in their own slices, and APIs should be designed to promote application development. We believe a testbed that supports these design principles will facilitate the emergence of a new service-oriented network architecture. Towards this end, the paper also briefly describes PlanetLab, an overlay network being designed with these four principles in mind.\",\n \"Title: Effective distributed scheduling of parallel workloads\\nYear: 1996\\n\\nAbstract: We present a distributed algorithm for time-sharing parallel workloads that is competitive with coscheduling. Implicit scheduling allows each local scheduler in the system to make independent decisions that dynamically coordinate the scheduling of cooperating processes across processors. Of particular importance is the blocking algorithm which decides the action of a process waiting for a communication or synchronization event to complete. Through simulation of bulk-synchronous parallel applications, we find that a simple two-phase fixed-spin blocking algorithm performs well; a two-phase adaptive algorithm that gathers run-time data on barrier wait-times performs slightly better. Our results hold for a range of machine parameters and parallel program characteristics. These findings are in direct contrast to the literature that states explicit coscheduling is necessary for fine-grained programs. We show that the choice of the local scheduler is crucial, with a priority-based scheduler performing two to three times better than a round-robin scheduler. Overall, we find that the performance of implicit scheduling is near that of coscheduling (+/- 35%), without the requirement of explicit, global coordination.\",\n \"Title: The impact of flexible loads in increasingly renewable grids.\\nYear: 2013\\n\\nAbstract: We develop a flexible and responsive electrical load in the form of domestic refrigerators augmented with a thermal storage system, a wireless sensor network for monitoring and actuation, and a controller that enables response to external controls. Using this, we investigate the potential of such loads for two applications: price-responsive demand and supply-following. Our prototype shows that with a 13% increase in refrigerator electricity consumption, we are able to avoid electricity consumption for over six hours. We employ a methodology for creating models of electricity grids with high renewables penetration, and study the effects of deploying variable populations of flexible energy storage refrigerators in grids at variable levels of renewables penetration. Our results show that our prototype can respond to time-of-use price tariffs to reduce summer refrigeration electricity cost by up to 13% on the consumer side, while substantially reducing the capital investment on the utility side by smoothing the peak. At higher levels of renewables penetration, with 20% of refrigerators in California adopting this technology and acting as supply-following electricity loads, flexible refrigerators can shave off 5% of peak capacity needs. The approach naturally extends to similar applications in thermal management of buildings and would operate in concert with other load management efforts such as smart vehicle charging.\",\n \"Title: A transmission control scheme for media access in sensor networks\\nYear: 2001\\n\\nAbstract: We study the problem of media access control in the novel regime of sensor networks, where unique application behavior and tight constraints in computation power, storage, energy resources, and radio technology have shaped this design space to be very different from that found in traditional mobile computing regime. Media access control in sensor networks must not only be energy efficient but should also allow fair bandwidth allocation to the infrastructure for all nodes in a multihop network. We propose an adaptive rate control mechanism aiming to support these two goals and find that such a scheme is most effective in achieving our fairness goal while being energy efficient for both low and high duty cycle of network traffic.\",\n \"Title: Lessons from a Sensor Network Expedition\\nYear: 2004\\n\\nAbstract: Habitat monitoring is an important driving application for wireless sensor networks (WSNs). Although researchers anticipate some challenges arising in the real-world deployments of sensor networks, a number of problems can be discovered only through experience. This paper evaluates a sensor network system described in an earlier work and presents a set of experiences from a four month long deployment on a remote island off the coast of Maine. We present an in-depth analysis of the environmental and node health data. The close integration of WSNs with. their environment provides biological data at densities previous impossible; however, we show that the sensor data is also useful for predicting system operation and network failures. Based on over one million data and health readings, we analyze the node and network design and develop network reliability profiles and failure models.\",\n \"Title: Cluster I/O with River: making the fast case common\\nYear: 1999\\n\\nAbstract: We introduce River, a data-flow programming environment and I/O substrate for clusters of computers. River is designed to provide max- imum performance in the common case — even in the face of non- uniformities in hardware, software, and workload. River is based on two simple design features: a high-performance distributed queue, and a storage redundancy mechanism called graduated declustering. We have implemented a number of data-intensive applications on River, which validate our design with near-ideal performance in a variety of non-uniform performance scenarios.\",\n \"Title: Guest Editors' Introduction: Overview of Sensor Networks\\nYear: 2004\\n\\nAbstract: Wireless sensor networks could advance many scientific pursuits while providing a vehicle for enhancing various forms of productivity, including manufacturing, agriculture, construction, and transportation.\",\n \"Title: Operating system support for planetary-scale network services\\nYear: 2004\\n\\nAbstract: PlanetLab is a geographically distributed overlay network designed to support the deployment and evaluation of planetary-scale network services. Two high-level goals shape its design. First, to enable a large research community to share the infrastructure, PlanetLab provides distributed virtualization, whereby each service runs in an isolated slice of PlanetLab's global resources. Second, to support competition among multiple network services, PlanetLab decouples the operating system running on each node from the network-wide services that define PlanetLab, a principle referred to as unbundled management. This paper describes how Planet-Lab realizes the goals of distributed virtualization and unbundled management, with a focus on the OS running on each node.\",\n \"Title: Ninja: A Framework for Network Services\\nYear: 2002\\n\\nAbstract: Ninja is a new framework that makes it easy to create robust scalable Internet services. We introduce a new programming model based on the natural parallelism qflarge-scale services, and show how to implement the model. The first key aspect of the model is intelligent connection management, which enables high availability, load balancing, graceful degradation and online evolution. The second key aspect is support for shared persistent state that is automatically partitioned for scalability and replicated for fault tolerance. We discuss two versions of shared state, a cluster-based hash table with transparent replication and novel features that reduce lock contention, and a cluster-based file system that provides local transactions and cluster-wide namespaces and replication. Using several applications we show that the framework enables the creation of scalable, highly available services with persistent data, with very little application code - as little as one-tenth the code size of comparable stand-alone applications.\",\n \"Title: Separation constraint partitioning: a new algorithm for partitioning non-strict programs into sequential threads\\nYear: 1995\\n\\nAbstract: In this paper we present substantially improved thread partitioning algorithms for modern implicitly parallel languages. We present a new block partitioning algorithm, separation constraint partitioning, which is both more powerful and more flexible than previous algorithms. Our algorithm is guaranteed to derive maximal threads. We present a theoretical framework for proving the correctness of our partitioning approach, and we show how separation constraint partitioning makes interprocedural partitioning viable.We have implemented the partitioning algorithms in an Id90 compiler for workstations and parallel machines. Using this experimental platform, we quantify the effectiveness of different partitioning schemes on whole applications.\",\n \"Title: Lazy threads: implementing a fast parallel call\\nYear: 1996\\n\\nAbstract: In this paper, we describe lazy threads, a new approach for implementing multithreaded execution models on conventional machines. We show how they can implement a parallel call at nearly the efficiency of a sequential call. The central idea is to specialize the representation of a parallel call so that it can execute as a parallel-ready sequential call. This allows excess parallelism to degrade into sequential calls with the attendant efficient stack management and direct transfer of control and data, yet a call that truly needs to execute in parallel, gets its own thread of control. The efficiency of lazy threads is achieved through a careful attention to storage management and a code generation strategy that allows us to represent potential parallel work with no overhead. © 1996 Academic Press, Inc.\",\n \"Title: PlanetLab: an overlay testbed for broad-coverage services\\nYear: 2003\\n\\nAbstract: PlanetLab is a global overlay network for developing and accessing broad-coverage network services. Our goal is to grow to 1000 geographically distributed nodes, connected by a disverse collection of links. PlanetLab allows multiple service to run concurrently and continuously, each in its own slice of PlanetLab. This paper discribes our initial implementation of PlanetLab, including the mechanisms used to impelment virtualization, and the collection of core services used to manage PlanetLab.\",\n \"Title: Empirical evaluation of the CRAY-T3D: a compiler perspective\\nYear: 1995\\n\\nAbstract: Most recent MPP systems employ a fast microprocessor surrounded by a shell of communication and synchronization logic. The CRAY-T3D provides an elaborate shell to support global-memory access, prefetch, atomic operations, barriers, and block transfers. We provide a detailed empirical performance characterization of these primitives using micro-benchmarks and evaluate their utility in compiling for a parallel language. We have found that the raw performance of the machine is quite impressive and the most effective forms of communication are prefetch and write. Other shell provisions, such as the bulk transfer engine and the external Annex register set, are cumbersome and of little use. By evaluating the system in the context of a language implementation, we shed light on important trade-offs and pitfalls in the machine architecture.\",\n \"Title: Integrating concurrency control and energy management in device drivers\\nYear: 2007\\n\\nAbstract: Energy management is a critical concern in wireless sensornets. Despite its importance, sensor network operating systems today provide minimal energy management support, requiring applications to explicitly manage system power states. To address this problem, we present ICEM, a device driver architecture that enables simple, energy efficient wireless sensornet applications. The key insight behind ICEMis that the most valuable information an application can give the OS for energy management is its concurrency. Using ICEM, a low-rate sensing application requires only a single line of energy management code and has an efficiency within 1.6% of a hand-tuned implementation. ICEM's effectiveness questions the assumption that sensornet applications must be responsible for all power management and sensornets cannot have a standardized OS with a simple API.\",\n \"Title: Flexibility of Commercial Building HVAC Fan as Ancillary Service for Smart Grid.\\nYear: 2013\\n\\nAbstract: In this paper, we model energy use in commercial buildings using empirical data captured through sMAP, a campus building data portal at UC Berkeley. We conduct at-scale experiments in a newly constructed building on campus. By modulating the supply duct static pressure (SDSP) for the main supply air duct, we induce a response on the main supply fan and determine how much ancillary power flexibility can be provided by a typical commercial building. We show that the consequent intermittent fluctuations in the air mass flow into the building does not influence the building climate in a human-noticeable way. We estimate that at least 4 GW of regulation reserve is readily available only through commercial buildings in the US. Based on predictions this value will reach to 5.6 GW in 2035. We also show how thermal slack can be leveraged to provide an ancillary service to deal with transient frequency fluctuations in the grid. We consider a simplified model of the grid power system with time varying demand and generation and present a simple control scheme to direct the ancillary service power flow from buildings to improve on the classical automatic generation control (AGC)-based approach. Simulation results are provided to show the effectiveness of the proposed methodology for enhancing grid frequency regulation.\",\n \"Title: Building MPI for Multi-Programming Systems Using Implicit Information\\nYear: 1999\\n\\nAbstract: With the growing importance of fast system area networks in the parallel community, it is becoming common for message passing programs to run in multi-programming environments. Competing sequential and parallel jobs can distort the global coordination of communicating processes. In this paper, we describe our implementation of MPI using implicit information for global coscheduling. Our results show that MPI program performance is, indeed, sensitive to local scheduling variations. Further, the integration of implicit co-scheduling with the MPI runtime system achieves robust performance in a multiprogramming environment, without compromising performance in dedicated use.\",\n \"Title: Data Compression Technology Dedicated to Distribution and Embedded Systems\\nYear: 2010\\n\\nAbstract: Summary form only given. In distribution and embedded systems, data compression is often used to reduce the size of flash RAM and transmission data, while a rapid decompression speed enables faster rebooting of the compressed program code. We have developed a new data compression algorithm with a high decompression speed and a good compression rate that is equivalent to zlib, the standard technology in use today. We created a LZSS-based algorithm by optimizing the parsing of data strings. LZSS is known as a high decompression speed algorithm useful for embedded systems, and optimal parsing is well known as a method for improving compression rates. Previously, this combination had not been implemented because statistical code length varies during optimal parsing. Our algorithm overcomes this problem by calculating the probability of the literal or the code ( distance and length ) solving the shortest path problem first. It then constructs a simple code set that enables fast decompression using those probabilities and solves the shortest path problem again. Experiments on the standard evaluation data and wireless sensor network program demonstrated that we can achieve a high compression rate equivalent to zlib and a decompression speed that is twice as fast.\",\n \"Title: Compiler-controlled multithreading for lenient parallel languages\\nYear: 1991\\n\\nAbstract: Tolerance to communication latency and inexpensive synchronization are critical for general-purpose computing on large multiprocessors. Fast dynamic scheduling is required for powerful non-strict parallel languages. However, machines that support rapid switching between multiple execution threads remain a design challenge. This paper explores how multithreaded execution can be addressed as a compilation problem, to achieve switching rates approaching what hardware mechanisms might provide. Compiler-controlled multithreading is examined through compilation of a lenient parallel language, Id90, for a threaded abstract machine, TAM. A key feature of TAM is that synchronization is explicit and occurs only at the start of a thread, so that a simple cost model can be applied. A scheduling hierarchy allows the compiler to schedule logically related threads closely together in time and to use registers across threads. Remote communication is via message sends and split-phase memory accesses. Messages and memory replies are received by compiler-generated message handlers which rapidly integrate these events with thread scheduling. To compile Id90for TAM, we employ a new parallel intermediate form, dual-graphs, with distinct control and data arcs. This provides a clean framework for partitioning the program into threads, scheduling threads, and managing registers under asynchronous execution. The compilation process is described and preliminary measurements show that the cost of compiler-controlled multithreading is within a small factor of the cost of control flow in sequential languages.\",\n \"Title: Introduction to the Special Section on Dependable Network Computing\\nYear: 2001\\n\\nAbstract: First Page of the Article\",\n \"Title: U-Net/SLE: A Java-based user-customizable virtual network interface\\nYear: 1999\\n\\nAbstract: We describe U-Net/SLE (Safe Language Extensions), a user-level network interface architecture which enables per-application customization of communication semantics through downloading of user extension applets, implemented as Java classfiles, to the network interface. This architecture permits applications to safely specify code to be executed within the NI on message transmission and reception. By leveraging the existing U-Net model, applications may implement protocol code at the user level, within the NI, or using some combination of the two. Our current implementation, using the Myricom Myrinet interface and a small Java Virtual Machine subset, allows host communication overhead to be reduced and improves the overlap of communication and computation during protocol processing.\",\n \"Title: Achieving Robust, Scalable Cluster I/O in Java\\nYear: 2000\\n\\nAbstract: We present Tigris, a high-performance computation and I/O substrate for clusters of workstations that is implemented entirely in Java. Tigris automatically balances resource load across the cluster as a whole, shielding applications from asymmetries in CPU, I/O, and network performance. This is accomplished through the use of a dataflow programming model coupled with a work-balancing distributed queue. To meet the performance challenges of implementing such a system in Java, Tigris relies on Jaguar, a system that enables direct, protected access to hardware resources, including fast network interfaces and disk I/O. Jaguar yields an order-of-magnitude performance boost over the Java Native Interface for Java bindings to system resources. We demonstrate the applicability of Tigris through a one-pass, parallel, disk-to-disk sort exhibiting high performance.\",\n \"Title: IP is dead, long live IP for wireless sensor networks\\nYear: 2008\\n\\nAbstract: A decade ago as wireless sensor network research took off many researchers in the field denounced the use of IP as inadequate and in contradiction to the needs of wireless sensor networking. Since then the field has matured, standard links have emerged, and IP has evolved. In this paper, we present the design of a complete IPv6-based network architecture for wireless sensor networks. We validate the architecture with a production-quality implementation that incorporates many techniques pioneered in the sensor network community, including duty-cycled link protocols, header compression, hop-by-hop forwarding, and efficient routing with effective link estimation. In addition to providing interoperability with existing IP devices, this implementation was able to achieve an average duty-cycle of 0.65%, average per-hop latency of 62ms, and a data reception rate of 99.98% over a period of 4 weeks in a real-world home-monitoring application where each node generates one application packet per minute. Our results outperform existing systems that do not adhere to any particular standard or architecture. In light of this demonstration of full IPv6 capability, we review the central arguments that led the field away from IP. We believe that the presence of an architecture, specifically an IPv6-based one, provides a strong foundation for wireless sensor networks going forward.\",\n \"Title: The Ten Hottest Topics in Parallel and Distributed Computing for the Next Millennium\\nYear: 2000\\n\\nAbstract: What will be the fundamental issues and ideas that will define parallel and distributed computing during the next millennium? In this panel, a group of distinguished researchers will make the case for their candidates. You decide whether you agree, or stand up and make the case for the ideas that you think are important! The panelists include noted and opinionated experts in parallel computing, distributed-computing, and applications, so the discussion is guaranteed to be lively and informative.\",\n \"Title: Design And Implementation Of A Sensor Network System For Vehicle Tracking And Autonomous Interception\\nYear: 2005\\n\\nAbstract: We describe the design and implementation of PEG, a networked system of distributed sensor nodes that detects an uncooperative agent called the evader and assists an autonomous robot called the pursuer in capturing the evader. PEG requires embedded network services such as leader election, routing, network aggregation, and closed loop control. Instead of using general purpose distributed system solutions for these services, we employ whole-system analysis and rely on spatial and physical properties to create simple and efficient mechanisms. We believe this approach advances sensor network design, yielding pragmatic solutions that leverage physical properties to simplify design of embedded distributed systems.We deployed PEG on a 400 square meter field using 100 sensor nodes, and successfully intercepted the evader in all runs. We confronted practical issues such as node breakage, packaging decisions, in situ debugging, network reprogramming, and system reconfiguration. We discuss the approaches we took to cope with these issues and share our experiences in deploying a realistic outdoor sensor network system.\",\n \"Title: Software design patterns for TinyOS\\nYear: 2007\\n\\nAbstract: We present design patterns used by software components in the TinyOS sensor network operating system. They differ significantly from traditional software design patterns because of the constraints of sensor networks and to TinyOS's focus on static allocation and whole-program composition. We describe how nesC has evolved to support these design patterns by including a few simple language primitives and optimizations.\",\n \"Title: Architectural requirements and scalability of the NAS parallel benchmarks\\nYear: 1999\\n\\nAbstract: We present a study of the architectural requirements and scalability of the NAS Parallel Benchmarks. Through direct measurements and simulations, we identify the factors which affect the scalability of benchmark codes on two relevant and distinct platforms; a cluster of workstations and a ccNUMA SGI Origin 2000. We find that the benefit of increased global cache size is pronounced in certain applications and often offsets the communication cost. By constructing the working set profile of the benchmarks, we are able to visualize the improvement of computational efficiency under constant-problem-size scaling. We also find that, while the Origin MPI has better point-to-point performance, the cluster MPI layer is more scalable with communication load. However, communication performance within the applications is often much lower than what would be achieved by micro-benchmarks. We show that the communication protocols used by MPI runtime library are influential to the communication performance in applications, and that the benchmark codes have a wide spectrum of communication requirements.\",\n \"Title: User-Centric Performance Analysis of Market-Based Cluster Batch Schedulers\\nYear: 2002\\n\\nAbstract: This paper presents a performance analysis of market-basedbatch schedulers for clusters of workstations.In contrast to previous work, we use user-centric performance metrics as the basis for system evaluation.Each user is modeled as having a utility function for each job which measures value delivered to the user as function of execution time.Summing over all utility functions in the workload, we use aggregate utility as a measure of overall value delivered to users.With aggregate utility as the performance metric, simulations are used to quantify the performance of both market-based and traditional batch scheduling algorithms under a variety of synthetic work-loads.Results show that an auction-based batch scheduling algorithm improves performance by a factor of up to2-5x for sequential workloads and up to 14x for highly parallelworkloads compared to traditional scheduling algorithms.\",\n \"Title: Toward the sensor network macroscope\\nYear: 2005\\n\\nAbstract: The Macroscope is a conceptual instrument for perceiving complex interactions, such as what occurs is ecosystems, social systems, and large-scale industrial settings. Sensor networks are a significant step toward such an instrument, because of the fidelity they offer in monitoring large regions of space and large collections of things. This talk describes our experiences in developing and deploying a large sensor network for microclimate monitoring of coastal redwood forests as a basis for studies in redwood ecophysiology. It summarizes the architecture, its implementation, and the many lessons and surprises encountered along the way. The effort produced unprecedented recordings of the microclimate dynamics indicating how these huge organisms interact with their environment.\",\n \"Title: Design challenges of virtual networks: fast, general-purpose communication\\nYear: 1999\\n\\nAbstract: Virtual networks provide applications with the illusion of having their own dedicated, high-performance networks, although network interfaces posses limited, shared resources. We present the design of a large-scale virtual network system and examine the integration of communication programming interface, system resource management, and network interface operation. Our implementation on a cluster of 100 workstations quantifies the impact of virtualization on small message latencies and throughputs, shows full hardware performance is delivered to dedicated applications and time-shared workloads, and shows robust performance under demanding workloads that overcommit interface resources.\",\n \"Title: Reducing Transient and Steady State Electricity Consumption in HVAC Using Learning-Based Model-Predictive Control.\\nYear: 2012\\n\\nAbstract: Heating, ventilation, and air conditioning (HVAC) systems are an important target for efficiency improvements through new equipment and retrofitting because of their large energy footprint. One type of equipment that is common in homes and some offices is an electrical, single-stage heat pump air conditioner (AC). To study this setup, we have built the Berkeley Retrofitted and Inexpensive HVAC Tes...\",\n \"Title: The Architectural Costs of Streaming I/O: A Comparison of Workstations, Clusters, and SMPs\\nYear: 1998\\n\\nAbstract: We investigate resource usage while performing streaming I/O by con- trasting three architectures, a single workstation, a cluster, and an SMP, under various I/O benchmarks. We derive analytical and empirically- based models of resource usage during data transfer, examining the I/O bus, memory bus, network, and processor of each system. By investigating each resource in detail, we assess what comprises a well- balanced system for these workloads. We find that the architectures we study are not well balanced for streaming I/O applications. Across the platforms, the main limitation to attaining peak performance is the CPU, due to lack of data locality. Increasing processor performance (especially with improved block op- eration performance) will be of great aid for these workloads in the future. For a cluster workstation, the I/O bus is a major system bot- tleneck, because of the increased load placed on it from network com- munication. A well-balanced cluster workstation should have copious I/O bus bandwidth, perhaps via multiple I/O busses. The SMP suffers from poor memory-system performance; even when there is true par- allelism in the benchmark, contention in the shared-memory system leads to reduced performance. As a result, the clustered workstations provide higher absolute performance for streaming I/O workloads.\",\n \"Title: Evaluation of mechanisms for fine-grained parallel programs in the J-machine and the CM-5\\nYear: 1993\\n\\nAbstract: This paper uses an abstract machine approach to compare the mechanisms of two parallel machines: the J-Machine and the CM-5. High-level parallel programs are translated by a single optimizing compiler to a fine-grained abstract parallel machine, TAM. A final compilation step is unique to each machine and optimizes for specifics of the architecture. By determining the cost of the primitives and weighting them by their dynamic frequency in parallel programs, we quantify the effectiveness of the following mechanisms individually and in combination. Efficient processor/network coupling proves valuable. Message dispatch is found to be less valuable without atomic operations that allow the scheduling levels to cooperate. Multiple hardware contexts are of small value when the contexts cooperate and the compiler can partition the register set. Tagged memory provides little gain. Finally, the performance of the overall system is strongly influenced by the performance of the memory system and the frequency of control operations.\",\n \"Title: Energy Savings and the “Software-Defined” Building\\nYear: 2012\\n\\nAbstract: In the US buildings consume 70% of electricity, but the sector exhibits little innovation for reducing its consumption. Efficiency is not yet evaluated to the same standard as comfort and reliability, but with better user input, control policy, and awareness of the building's state, energy consumption can be intelligently reduced. It is argued that what is needed is a shift to Software-Defined Buildings: flexible, multi-service, and open Building Operating System (BOS) that allows third-party applications to run securely and reliably in a sandboxed environment. A BOS is not limited to a single building but distributed among multi-building campuses. It provides the core functionality of sensor and actuator access, access management, metadata, archiving, and discovery. The runtime environment enables multiple simultaneously running programs. As in a computer OS, these run with various privilege levels, with access to different resources, yet are multiplexed on the same physical resources. It can extend to the Cloud or to other buildings, outsourcing expensive or proprietary operations as well as load sharing, but does so safely with fail-over to local systems when connectivity is disrupted. Building operators have supervisory control over all programs, controlling the separation physically (access different controls), temporally (change controls at different times), informationally (what information leaves the building), and logically (what actions or sequences thereof are allowable).\",\n \"Title: Incremental network programming for wireless sensors\\nYear: 2004\\n\\nAbstract: We present an incremental network programming mechanism which re programs wireless sensors quickly by transmitting the incremental changes for the new program version. Using the Rsync algorithm we generate the difference of the two program images, which allows us to distribute just the key changes of the program. Unlike previous approaches, our design does not assume any prior knowledge of the program code structure and can be applied to any hardware platform. To meet the resource constraints of wireless sensors we tuned the Rsync algorithm which was originally made for updating binary files among computationally powerful machines. In our design, the sensor node processes the delivery and the decoding of the difference script in separate steps. This makes it easy to extend for multi-hop network programming. We are able to achieve the speedup of 9.1 for changing a constant and 2.1 to 2.5 for changing a few lines in the source code over the non-incremental delivery.\",\n \"Title: Global analysis for partitioning non-strict programs into sequential threads\\nYear: 1992\\n\\nAbstract: In this paper we present a new solution to the problem of compiling an eager, non-strict language into multiple sequential threads. The solution is described using an intermediate program form developed for the programming language Id [Nik90], a functional language extended with I-structures [ANP86] and M-structures [BNA91]. A similar intermediate form has also been suggested for imperative languages [BP89], as a way of exposing parallelism in those languages. With suitable restrictions, we believe our method is also appropriate for lazy, purely functional languages such as Haskell [HWe90]. Throughout this paper, a thread will mean a subset of the instructions comprising a procedure body, such that: 1. A compile-time instruction ordering can be determined for the thread which is valid for all contexts in which the containing procedure can be invoked.\",\n \"Title: Flexible Hardware Abstraction For Wireless Sensor Networks\\nYear: 2005\\n\\nAbstract: We present a flexible Hardware Abstraction Architecture (HAA) that balances conflicting requirements of Wireless Sensor Networks (WSNs) applications and the desire for increased portability and streamlined development of applications. Our three-layer design gradually adapts the capabilities of the underlying hardware platforms to the selected platform-independent hardware interface between the operating system core and the application code. At the same time, it allows the applications to utilize a platform's full capabilities - exported at the second layer, when the performance requirements outweigh the need for cross-platform compatibility. We demonstrate the practical value of our approach by presenting how it can be applied to the most important hardware modules that are found in a typical WSN platform. We support our claims using concrete examples from existing hardware abstractions in TinyOS and our implementation of the MSP430 platform that follows the architecture proposed in this paper.\",\n \"Title: The ganglia distributed monitoring system: design, implementation, and experience\\nYear: 2004\\n\\nAbstract: Ganglia is a scalable distributed monitoring system for high performance computing systems such as clusters and Grids. It is based on a hierarchical design targeted at federations of clusters. It relies on a multicast-based listen/announce protocol to monitor state within clusters and uses a tree of point-to-point connections amongst representative cluster nodes to federate clusters and aggregate their state. It leverages widely used technologies such as XML for data representation, XDR for compact, portable data transport, and RRDtool for data storage and visualization. It uses carefully engineered data structures and algorithms to achieve very low per-node overheads and high concurrency. The implementation is robust, has been ported to an extensive set of operating systems and processor architectures, and is currently in use on over 500 clusters around the world. This paper presents the design, implementation, and evaluation of Ganglia along with experience gained through real world deployments on systems of widely varying scale, configurations, and target application domains over the last two and a half years.\",\n \"Title: NFS sensitivity to high performance networks\\nYear: 1999\\n\\nAbstract: This paper examines NFS sensitivity to performance characteristics of emerging networks. We adopt an unusual method of inserting controlled delays into live systems to measure sensitivity to basic network parameters. We develop a simple queuing model of an NFS server and show that it reasonably characterizes our two live systems running the SPECsfs benchmark. Using the techniques in this work, we can infer the structure of servers from published SPEC results. Our results show that NFS servers are most sensitive to processor overhead; it can be the limiting factor with even a modest number of disks. Continued reductions in processor overhead will be necessary to realize performance gains from future multigigabit networks. NFS can tolerate network latency in the regime of newer LANs and IP switches. Due to NFS’s historic high mix of small metadata operations, NFS is quite insensitive to network bandwidth. Finally, we find that the protocol enhancements in NFS version 3 tolerate high latencies better than version 2 of the protocol.\",\n \"Title: Towards modeling the performance of a fast connected components algorithm on parallel machines\\nYear: 1995\\n\\nAbstract: We present and analyze a portable, high-performance algorithm for finding connected components on modern distributed memory multiprocessors. The algorithm is a hybrid of the classic DFS on the subgraph local to each processor and a variant of the Shiloach-Vishkin PRAM algorithm on the global collection of subgraphs. We implement the algorithm in Split-C and measure performance on the the Cray T3D, the Meiko CS-2, and the Thinking Machines CM-5 using a class of graphs derived from cluster dynamics methods in computational physics. On a 256 processor Cray T3D, the implementation outperforms all previous solutions by an order of magnitude. A characterization of graph parameters allows us to select graphs that highlight key performance features. We study the effects of these parameters and machine characteristics on the balance of time between the local and global phases of the algorithm and find that edge density, surface-to-volume ratio, and relative communication cost dominate performance. By understanding the effect of machine characteristics on performance, the study sheds light on the impact of improvements in computational and/or communication performance on this challenging problem.\",\n \"Title: High-performance sorting on networks of workstations\\nYear: 1997\\n\\nAbstract: We report the performance of NOW-Sort, a collection of sorting implementations on a Network of Workstations (NOW). We find that parallel sorting on a NOW is competitive to sorting on the large-scale SMPs that have traditionally held the performance records. On a 64-node cluster, we sort 6.0 GB in just under one minute, while a 32-node cluster finishes the Datamation benchmark in 2.41 seconds.Our implementations can be applied to a variety of disk, memory, and processor configurations; we highlight salient issues for tuning each component of the system. We evaluate the use of commodity operating systems and hardware for parallel sorting. We find existing OS primitives for memory management and file access adequate. Due to aggregate communication and disk bandwidth requirements, the bottleneck of our system is the workstation I/O bus.\",\n \"Title: REXEC: A Decentralized, Secure Remote Execution Environment for Clusters\\nYear: 2000\\n\\nAbstract: Bringing clusters of computers into the mainstream as general-purpose computing systems requires that better fa- cilities for transparent remote execution of parallel and se- quential applications be developed. While much research has been done in this area, most of this work remains inaccessible for clusters built using contemporary hardware and operating systems. Implementations are either too old and/or not pub- licly available, require use of operating systems which are not supported by modern hardware, or simply do not meet the functional requirements demanded by practical use in re- al world settings. To address these issues, we designed REX- EC, a decentralized, secure remote execution facility. It pro- vides high availability, scalability, transparent remote execu- tion, dynamic cluster configuration, decoupled node discov- ery and selection, a well-defined failure and cleanup model, parallel and distributed program support, and strong authen- tication and encryption. The system is implemented and is currently installed and in use on a 32-node cluster of 2-way SMPs running the Linux 2.2.5 operating system.\",\n \"Title: Connecting low-power and lossy networks to the internet.\\nYear: 2011\\n\\nAbstract: Many applications, ranging from wireless healthcare to energy metering on the smart grid, have emerged from a decade of research in wireless sensor networks. However, the lack of an IP-based network architecture precluded sensor networks from interoperating with the Internet, limiting their real-world impact. Given this disconnect, the IETF chartered the 6LoWPAN and RoLL working groups to specify ...\",\n \"Title: IPv6 in Low-Power Wireless Networks.\\nYear: 2010\\n\\nAbstract: With deeply embedded wireless sensors, a new tier of the Internet is emerging that will extend into the physical world. These wireless sensor nodes are expected to vastly outnumber conventional computer hosts as we see them today, but their strict resource constraints are unlike other technologies already common to the Internet. As wireless sensor network research took off, many in the field esche...\",\n \"Title: An information-centric energy infrastructure: The Berkeley view\\nYear: 2011\\n\\nAbstract: We describe an approach for how to design an essentially more scalable, flexible and resilient electric power infrastructure – one that encourages efficient use, integrates local generation, and manages demand through omnipresent awareness of energy availability and use over time. We are inspired by how the Internet has revolutionized communications infrastructure, by pushing intelligence to the edges while hiding the diversity of underlying technologies through well-defined interfaces. Any end device is a traffic source or sink and intelligent endpoints adapt their traffic to what the infrastructure can support. Our challenge is to understand how these principles can be suitably applied in formulating a new information-centric energy network for the 21st Century. We believe that an information-centric approach can achieve significant efficiencies in how electrical energy is distributed and used. The existing Grid assumes energy is cheap and information about its generation, distribution and use is expensive. Looking forward, energy will be dear, but pervasive information will allow us to use it more effectively, by agilely dispatching it to where it is needed, integrating intermittent renewable sources and intelligently adapting loads to match the available energy.\",\n \"Title: SPINS: security protocols for sensor networks\\nYear: 2002\\n\\nAbstract: As sensor networks edge closer towards wide-spread deployment, security issues become a central concern. So far, much research has focused on making sensor networks feasible and useful, and has not concentrated on security.We present a suite of security building blocks optimized for resource-constrained environments and wireless communication. SPINS has two secure building blocks: SNEP and &mgr;TESLA SNEP provides the following important baseline security primitives: Data confidentiality, two-party data authentication, and data freshness. A particularly hard problem is to provide efficient broadcast authentication, which is an important mechanism for sensor networks. &mgr;TESLA is a new protocol which provides authenticated broadcast for severely resource-constrained environments. We implemented the above protocols, and show that they are practical even on minimal hardware: the performance of the protocol suite easily matches the data rate of our network. Additionally, we demonstrate that the suite can be used for building higher level protocols.\",\n \"Title: Securing the deluge Network programming system\\nYear: 2006\\n\\nAbstract: A number of multi-hop, wireless, network programming systems have emerged for sensor network retasking but none of these systems support a cryptographically-strong, public-key-based system for source authentication and integrity verification. The traditional technique for authenticating a program binary, namely a digital signature of the program hash, is poorly suited to resource-contrained sensor nodes. Our solution to the secure programming problem leverages authenticated streams, is consistent with the limited resources of a typical sensor node, and can be used to secure existing network programming systems. Under our scheme, a program binary consists of several code and data segments that are mapped to a series of messages for transmission over the network. An advertisement, consisting of the program name, version number, and a hash of the very first message, is digitally signed and transmitted first. The advertisement authenticates the first message, which in turn contains a hash of the second message. Similarly, the second message contains a hash of the third message, and so on, binding each message to the one logically preceding it in the series through the hash chain. We augmented the Deluge network programming system with our protocol and evaluated the resulting system performance.\",\n \"Title: BUSICO 3D: building simulation and control in unity 3D\\nYear: 2014\\n\\nAbstract: In this demonstration, we present a novel system of building control and simulation focused on the integration of the physical and virtual worlds. Actuations and schedules can be manifested either in a physical space or in a virtualization of that space, allowing for more natural interactions with simulations and easier transferring of schedules and configurations from the simulated virtual environment to a real-world deployment. We provide an implementation using a widely used game engine (Unity 3D) and sMAP (Simple Measurement and Actuation Profile), a developed time series database and metadata store.\",\n \"Title: A networked embedded system platform for the post-mote era\\nYear: 2014\\n\\nAbstract: For the last fifteen years, research explored the hardware, software, sensing, communication abstractions, languages, and protocols that could make networks of small, embedded devices---motes---sample and report data for long periods of time unattended. Today, the application and technological landscapes have shifted, introducing new requirements and new capabilities. Hardware has evolved past 8 and 16 bit microcontrollers: there are now 32 bit processors with lower energy budgets and greater computing capability. New wireless link layers have emerged, creating protocols that support rapid and efficient setup and teardown but introduce novel limitations that systems must consider. The time has come to look beyond optimizing networks of motes. We look towards new technologies such as Bluetooth Low Energy, Cortex M processors, and capable energy harvesting, with new application spaces such as personal area networks, and new capabilities and requirements in security and privacy to inform contemporary hardware and software platforms. It is time for a new, open experimental platform in this post-mote era.\",\n \"Title: Mica: a wireless platform for deeply embedded networks\\nYear: 2002\\n\\nAbstract: Low-power integration of sensing, communication, and computation requires a new approach to wireless design. Flexible interfaces and primitive accelerators enable aggressive system-level optimizations. Mica's flexible design serves as a building block for creating efficient application-specific protocols. Instead of defining narrow, standardized application interfaces, Mica provides a set of richly interconnected primitives (such as data serializers and timing extractors) to facilitate cross-layer optimizations. To explore novel systems approaches, researchers can develop customized protocols tailored to their application; Mica does not require use of predefined protocols.\",\n \"Title: A case for NOW (Networks of Workstations)\\nYear: 1995\\n\\nAbstract: In this paper, we argue that because of recent technology advances, networks of workstations (NOWs) are poised to become the primary computing infrastructure for science and engineering, from low end interactive computing to demanding sequential and parallel applications. We identify three opportunities for NOWs that will benefit end- users: dramatically improving virtual memory and file system performance by using the aggregate DRAM of a NOW as a giant cache for disk; achieving cheap, highly available, and scalable file storage by using redundant arrays of workstation disks, using the LAN as the I/O backplane; and finally, multiple CPUs for parallel computing. We describe the technical challenges in exploiting these opportunities - namely, efficient communication hardware and software, global coordination of multiple workstation operating systems, and enterprise-scale network file systems. We are currently building a 100-node NOW prototype to demonstrate that practical solutions exist to these technical challenges.\",\n \"Title: Fast parallel sorting under LogP: experience with the CM-5\\nYear: 1996\\n\\nAbstract: In this paper, we analyze four parallel sorting algorithms (bitonic, column, radix, and sample sort) with the LogP model. LogP characterizes the performance of modern parallel machines with a small set of parameters: the communication latency (L), overhead (o), bandwidth (g), and the number of processors (P). We develop implementations of these algorithms in Split-C, a parallel extension to C, and compare the performance predicted by LogP to actual performance on a CM-5 of 32 to 512 processors for a range of problem sizes. We evaluate the robustness of the algorithms by varying the distribution and ordering of the key values. We also briefly examine the sensitivity of the algorithms to the communication parameters. We show that the LogP model is a valuable guide in the development of parallel algorithms and a good predictor of implementation performance. The model encourages the use of data layouts which minimize communication and balanced communication schedules which avoid contention. With an empirical model of local processor performance, LogP predictions closely match observed execution times on uniformly distributed keys across a broad range of problem and machine sizes. We find that communication performance is oblivious to the distribution of the key values, whereas the local processor performance is not; some communication phases are sensitive to the ordering of keys due to contention. Finally, our analysis shows that overhead is the most critical communication parameter in the sorting algorithms\",\n \"Title: Benchmarking message passing performance using MPI\\nYear: 1996\\n\\nAbstract: This paper describes a set of microbenchmarks for measuring the performance characteristics of MPI implementations. We explain the rationale behind the benchmarks and present the benchmark results on the Intel Paragon, IBM SP2, and SGI Power Challenge. Our measurements reveal how the hardware architecture and the underlying MPI implementation affect the message passing performance on the three platforms\",\n \"Title: Virtual network transport protocols for Myrinet\\nYear: 1998\\n\\nAbstract: Bringing direct and protected network multiprogramming into mainstream cluster computing requires innovations in three key areas: application programming interfaces, network virtualization systems, and lightweight communication protocols for high-speed interconnects. The AM-II API extends traditional active messages with support for client-server computing and facilitates the construction of parallel clients and distributed servers. Our virtual network segment driver enables a large number of arbitrary sequential and parallel applications to access network interface resources directly in a concurrent but fully protected manner. The NIC-to-NIC communication protocols provide reliable and at-most-once message delivery between communication endpoints. The NIC-to-NIC protocols perform well as the number of endpoints and the number of hosts in the cluster are scaled. The flexibility afforded by the underlying protocols enables a diverse set of timely research efforts. Other Berkeley researchers are actively using this system to investigate implicit techniques for the coscheduling of communicating processes, an essential part of high-performance communications in multiprogrammed clusters of uni- and multiprocessor servers. Other researchers are extending the active message protocols described here for clusters of symmetric multiprocessors, using so-called multiprotocol techniques and multiple network interfaces per machine\",\n \"Title: Distributed Computation in the Physical World\\nYear: 2005\\n\\nAbstract: Summary form only given. Networks of intelligent sensors that are distributed through the physical world will revolutionize practices in the life sciences, civil engineering, manufacturing, security, agriculture, ubiquitous computing, and many other areas. They also present an opportunity and a need to explore distributed algorithms that are wedded to the noisy, localized, time varying physical world. Bandwidth, storage, and energy limitations make in-network processing essential - within the node and among collections of nodes. The algorithms should be resource efficient, but also deal with noise, uncertainty and dynamically changing connectivity. A broad research community has been exploring these issues in the context of TinyOS and the Berkeley motes. This talk will highlight novel distributed algorithms coming out of these efforts and discuss issues in making such networks robust and programmable\",\n \"Title: Extending IP to Low-Power, Wireless Personal Area Networks\\nYear: 2008\\n\\nAbstract: Extending IP to low-power, wireless personal area networks (LoWPANs) was once considered impractical because these networks are highly constrained and must operate unattended for multiyear lifetimes on modest batteries. Many vendors embraced proprietary protocols, assuming that IP was too resource-intensive to be scaled down to operate on the microcontrollers and low-power wireless links used in LoWPAN settings. However, 6LoWPAN radically alters the calculation by introducing an adaptation layer that enables efficient IPv6 communication over IEEE 802.15.4 LoWPAN links.\",\n \"Title: Keynote 2: Pervasive communication and interaction to make the built environment better and more sustainable\\nYear: 2013\\n\\nAbstract: Over the past 15 years we have created a robust base of embedded networking technology to enable the `macroscope' - the ability to observe complex interactions of physical systems over a substantial extent of space and time. Created to understand the ecophysiology of natural systems, this technology is finding many natural applications in the quest to improve the sustainability of the built environment. In this talk we explore the role of pervasive computing and communications in buildings - where, in the US, we spend 90% of our time, over 70% of our electrical energy, and nearly 50% of our GHG emissions. We examine how pervasive monitoring serves to identify waste and opportunities for energy efficiency; how diverse sources of physical information can be homogenized to enable an innovative application ecosystem; and how a building operating system and services can provide a foundation for advanced control techniques that operate in concert with external factors, such as energy availability and weather, and for personalized environmental conditioning. To be quaint, ”there's a building app for that\\\".\",\n \"Title: Classification of sidewalks in street view images\\nYear: 2013\\n\\nAbstract: Mapping sidewalks in urban environments is key in the creation of pedestrian-friendly, sustainable cities. Currently, urban planners are hindered by a lack of information available in a format suitable for the large-scale analysis of sidewalk design. To demonstrate the impact that information technology could have in this area, we leverage techniques from machine learning and computer vision to gather information about the presence and quality of sidewalks in map images. In particular, we identify sidewalk segments in street view images using a random forest classifier, utilizing a set of local and global features that include geometric context, presence of lanes, pixel color, and location. Our results illustrate that this approach is effective in classifying sidewalk segments in a large set of street view images. This algorithm can be easily extended to other datasets, and can be automated to gather complete, fine-grained details about sidewalks for arbitrarily large urban environments.\",\n \"Title: Enabling advanced environmental conditioning with a building application stack\\nYear: 2013\\n\\nAbstract: There is enormous potential for building-focused applications to improve operation and sustainability, both for classical uses like modeling or fault detection as well as innovative ones like occupant-driven control or grid-aware energy management. We show that a building application stack - that addresses shortcomings of existing antiquated architectures by democratizing sensor data, constructing a framework for reliable and fault-tolerant operation of concurrent applications, and establishing an application programming interface to promote portability throughout the building stock - enables development of advanced applications. We observe the growing importance of applications that integrate sensors and actuators from the building infrastructure with those from “add-on” networks, and show how this design pattern is further empowered by the architecture. To prove the efficacy of the approach, we implement two advanced environmental conditioning applications on a large, commercial building that was not designed for either of them: a demand-controlled ventilation (DCV) system for balancing air quality considerations and energy use in conference and class room settings and a demand-controlled filtration (DCF) system for conserving recirculating fan energy in an intermittently occupied cleanroom setting. The DCV application is able to reduce air quality threshold violations by over 95% and concurrently reduce ventilation energy consumption by over 80%, while the DCF application can reduce recirculating fan power consumption by half with no repercussions on air quality when the room is occupied. Further, the portability of these applications highlights the potential of the architecture to enable widespread and rapid application development throughout the building stock.\",\n \"Title: A comparative study of high renewables penetration electricity grids\\nYear: 2013\\n\\nAbstract: Electricity grids are transforming as renewables proliferate, yet operational concerns due to fluctuations in renewables sources could limit the ultimate potential for high penetrations of renewables. In this paper, we compare three electricity grids - California, Germany, and Ontario - studying the effects of relative cost of solar and wind generation on the selection of the renewables mix, and examine the resulting excess generation. We then observe the effects of the renewables mix and the use of baseload energy generation on the limits to renewables penetration, quantifying what proportion of delivered energy can be provided by renewables. Our study shows that the optimal renewables mix, from the perspective of minimizing total cost of generation, is highly dependent on the relative costs of technology, and that above a certain penetration rate, different for each grid, the optimal mix must contain both solar and wind generation.\",\n \"Title: E-mission: Automated transportation emission calculation using smartphones\\nYear: 2015\\n\\nAbstract: Tracking travel patterns and modes is useful on many levels. Prior efforts to collect this information have been stymied by low accuracies or reliance on supplementary devices. One technique to overcome low accuracies is to use prompted recall, in which the user is prompted to supply the ground truth for automatically generated information. However, prompted recall increases the burden on the user, which could lead to low adoption or high drop out rates. Using techniques from behavioral economics, and prompting directly on the smartphone can reduce user burden, and also increase engagement for ongoing data collection. In this paper, we describe a system that improves accuracy by using behavioral techniques for prompted recall on the smartphone, and aggregates the information to help detect large scale patterns. We also present the evaluation of a prototype implementation that was used to collect data from 44 unpaid volunteers in the San Francisco Bay Area over 3 months and compute their transportation carbon footprint.\",\n \"Title: DISTIL: Design and implementation of a scalable synchrophasor data processing system\\nYear: 2015\\n\\nAbstract: The introduction and deployment of cheap, high precision, high-sample-rate next-generation synchrophasors en masse in both the transmission and distribution tier - while invaluable for event diagnosis, situational awareness and capacity planning - poses a problem for existing methods of phasor data analysis and storage. Addressing this, we present the design and implementation of a novel architecture for synchrophasor data analysis on distributed commodity hardware. At the core is a new feature-rich timeseries store, BTrDB. Capable of sustained writes and reads in excess of 16 million points per second per cluster node, advanced query functionality and highly efficient storage, this database enables novel analysis and visualization techniques. Leveraging this, a distillate framework has been developed that enables agile development of scalable analysis pipelines with strict guarantees on result integrity despite asynchronous changes in data or out of order arrival. Finally, the system is evaluated in a pilot deployment, archiving more than 216 billion raw datapoints and 515 billion derived datapoints from 13 devices in just 3.9TB. We show that the system is capable of scaling to handle complex analytics and storage for tens of thousands of next-generation synchrophasors on off-the-shelf servers.\",\n \"Title: Ownership is theft: experiences building an embedded OS in rust\\nYear: 2015\\n\\nAbstract: Rust, a new systems programming language, provides compile-time memory safety checks to help eliminate runtime bugs that manifest from improper memory management. This feature is advantageous for operating system development, and especially for embedded OS development, where recovery and debugging are particularly challenging. However, embedded platforms are highly event-based, and Rust's memory safety mechanisms largely presume threads. In our experience developing an operating system for embedded systems in Rust, we have found that Rust's ownership model prevents otherwise safe resource sharing common in the embedded domain, conflicts with the reality of hardware resources, and hinders using closures for programming asynchronously. We describe these experiences and how they relate to memory safety as well as illustrate our workarounds that preserve the safety guarantees to the largest extent possible. In addition, we draw from our experience to propose a new language extension to Rust that would enable it to provide better memory safety tools for event-driven platforms.\",\n \"Title: BTrDB: Optimizing Storage System Design for Timeseries Processing.\\nYear: 2016\\n\\nAbstract: The increase in high-precision, high-sample-rate telemetry timeseries poses a problem for existing timeseries databases which can neither cope with the throughput demands of these streams nor provide the necessary primitives for effective analysis of them. We present a novel abstraction for telemetry timeseries data and a data structure for providing this abstraction: a time-partitioning version-annotated copy-on-write tree. An implementation in Go is shown to outperform existing solutions, demonstrating a throughput of 53 million inserted values per second and 119 million queried values per second on a four-node cluster. The system achieves a 2.9× compression ratio and satisfies statistical queries spanning a year of data in under 200ms, as demonstrated on a year-long production deployment storing 2.1 trillion data points. The principles and design of this database are generally applicable to a large variety of timeseries types and represent a significant advance in the development of technology for the Internet of Things.\",\n \"Title: Short Paper: A Method for Discovering Functional Relationships Between Air Handling Units and Variable-Air-Volume Boxes From Sensor Data.\\nYear: 2015\\n\\nAbstract: In Building Automation Systems contextual information about sensors is frequently missing or hard-coded in the control code. Retrieving this data is time consuming and error-prone, but necessary to write any type of control application. Automating metadata acquisition is a new and active area of research. Methods to infer metadata from sensor labels or from recorded data have been previously proposed. However, these methods are ineffective in uncovering the association between HVAC components. In fact, measured variables (pressures, temperatures, flows, valve positions) have slow and attenuated responses to changes in input variables, thus impairing the efficacy of correlation methods. In addition, sensor readings are frequently constrained between physical limits and kept around setpoints by nested control loops. For this reason, pure statistical methods fail to capture the differences between sensor streams and are unable to classify them. In this article, we propose a new method for discovering functional relationships between Air Handling Units and Variable-Air-Volume Boxes from sensor data. The method utilizes perturbations of subsystem variables, while guaranteeing that the building zones remain within comfort boundaries. When applied to an existing building, our proposed method reveals correct associations in ~80% of the cases, and outperforms other methods.\",\n \"Title: Automated Metadata Construction to Support Portable Building Applications\\nYear: 2015\\n\\nAbstract: Commercial buildings consume nearly 19\\\\\\\\% of delivered energy in the U.S, nearly half (42%) of which is consumed in buildings with digital control systems comprised of wired sensor networks. These sensors have scant metadata, and are represented by ``tags'' which are obscure, building-specific and not machine parseable. We develop a human-in-the-loop synthesis technique which uses syntactic and data-driven steps to parse these sensor tags into a common namespace, which can enable portable building applications. We show that our technique allows an expert to fully parse a large fraction (~70%) of the tags with 24, 15 and 43 examples for three large commercial buildings comprising 1586, 2522 and 1865 sensors respectively, and deploy three portable applications on two buildings with less than 30 examples.\",\n \"Title: Poster Abstract: XBOS: An Extensible Building Operating System.\\nYear: 2015\\n\\nAbstract: We present XBOS, an eXtensible Building Operating System for integrated management of previously isolated building subsystems. The key contribution of XBOS is the Building Profile, a canonical, executable description of a building and its subsystems that changes with a building and evolves control processes and applications accordingly. The design and implementation of XBOS addresses the six dimensions of an effective BAS -- hardware presentation layer, canonical metadata, control process management, building evolution management, security, scalable UX and API.\",\n \"Title: Poster Abstract: Well-Connected Microzones for Increased Building Efficiency and Occupant Comfort.\\nYear: 2015\\n\\nAbstract: Personal Comfort Systems (PCS) are capable of maintaining occupant comfort in buildings despite large deviations from recommended \\\\\\\"comfortable\\\\\\\" temperatures. We present a novel digital controller for a well-studied (previously analog) PCS, allowing it to report real-time telemetry and respond to programmatic actuation requests. This enables the established capabilities of a PCS to be synergistically combined with occupant-aware building applications, providing new methods of comfort and energy efficiency maximization.\",\n \"Title: BearLoc: A Composable Distributed Framework for Indoor Localization Systems\\nYear: 2015\\n\\nAbstract: Many indoor localization algorithms have been proposed to enable location-based applications in indoor environments. However, these systems are monolithic and not component-based. We present BearLoc, a distributed modular framework for indoor localization systems that provides (1) natural development abstractions for sensor, algorithm, and application components, and (2) easy and flexible component composition. We demonstrate the merits of BearLoc with an example use case. Our evaluation shows we can reduce developer lines of code by 60% while introducing acceptable network delay overhead.\",\n \"Title: System Design for a Synergistic, Low Power Mote/BLE Embedded Platform.\\nYear: 2016\\n\\nAbstract: Modern IoT prototyping platforms fall short in terms of energy efficiency, connectivity and software programming practices. We present the design of a new hardware and software platform that addresses these shortcomings by bringing together Mobile, Wearable, Maker and Wireless Sensor Network technologies to enable rapid prototyping with a high degree of synergy and energy efficiency. This is achieved in part by leveraging the Memory Protection Unit on modern microcontrollers along with a novel syscall interface to provide kernel / user isolation and a clean concurrency model. Such a design allows a wide range of languages to be used for application development without significant adaptation. We demonstrate how careful choice of application language allows the naturally asynchronous nature of embedded programming to be expressed cleanly and powerfully. Finally we evaluate the platform in several integrated use cases, providing examples of the capabilities introduced by Synergy.\",\n \"Title: Enabling Synergy in IoT: Platform to Service and Beyond\\nYear: 2017\\n\\nAbstract: To enable a prosperous Internet of Things, devices and services must be extensible and adapt to changes in the environment or user interaction patterns. These requirements manifest as a set of design principles for each of the layers in an IoT ecosystem, from hardware to cloud services. This paper gives concrete guidelines learned from building a full-stack Synergistic IoT platform.\",\n \"Title: The Once And Future Internet Of Everything.\\nYear: 2016\\n\\nAbstract: I am often asked these days, \\\\\\\"Is IoT really as transformative as all the buzz suggests, or is it a lot of hype?\\\\\\\" My answer is simply, \\\\\\\"Yes.\\\\\\\" And the road to here has been a fascinating interplay of academic research accomplishments, industry advances (often with other drivers), and standardization processes (for lack of a better term). It was predictable that today we would be poised for the \\\\\\\"next tier\\\\\\\" of the Internet to take off, but the endgame seems to be even messier than expected.\",\n \"Title: Optimizing The Diamond Lane: A More Tractable Carpool Problem And Algorithms\\nYear: 2016\\n\\nAbstract: Carpooling has been long deemed a promising approach to better utilizing existing transportation infrastructure. However, there are several reasons carpooling is still not the preferred mode of commute in the United States: first, complex human factors, including time constraints and not having right incentive structures, discourage the sharing of rides; second, algorithmic and technical barriers inhibit the development of online services for matching riders. In this work, we study algorithms for 3+ high-occupancy vehicle (HOV) lanes, which permit vehicles that hold three or more people. We focus on the technical barriers but also address the aforementioned human factors. We formulate the HOV3 Carpool problem, and show that it is NP-Complete. We thus pose the relaxed problem HOV3-Carpool problem, allowing groups of up to size three, and propose several methods for solving the problem of finding globally optimal carpool groups that may utilize these 3-HOV lanes. Our methods include local search, integer programming, and dynamic programming. Our local search methods include sampling-based (hill-climbing and simulated annealing), classical neighborhood search, and a hybrid random neighborhood search. We assess the methods numerically in terms of objective value and scalability. Our findings show that our sampling-based local search methods scale up to 100K agents, thereby improving upon related previous work (which studies up to 1000 agents). The hill climbing local search method converges significantly closer and faster towards a naive lower bound on cumulative carpooling cost.\",\n \"Title: Challenging the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL): A Survey.\\nYear: 2017\\n\\nAbstract: RPL is the IPv6 routing protocol for low-power and lossy networks, standardized by IETF in 2012 as RFC6550. Specifically, RPL is designed to be a simple and inter-operable networking protocol for resource-constrained devices in industrial, home, and urban environments, intended to support the vision of the Internet of Things with thousands of devices interconnected through multihop mesh networks. ...\",\n \"Title: Do Not Lose Bandwidth: Adaptive Transmission Power and Multihop Topology Control.\\nYear: 2017\\n\\nAbstract: We show that a multihop wireless network can achieve better bandwidth and routing stability when transmission power and routing topology are jointly and adaptively controlled. Our experiments show that the predominant u0027fixed and uniformu0027 transmission power strategy with u0027link quality and hop distanceu0027-based routing topology construction loses significant bandwidth due to hidden terminal and load imbalance problems. We design an adaptive and distributed control mechanism for transmission power and routing topology, PCRPL, within the standard RPL routing protocol. We implement PC-RPL on real embedded devices and evaluate its performance on a 49-node multihop testbed. PC-RPL reduces total end-to-end packet losses ~7-fold without increasing hop distance compared to RPL with the highest transmission power, resulting in 17% improvement in aggregate bandwidth and 64% for the worst-case node.\",\n \"Title: HodDB: a query processor for brick\\nYear: 2017\\n\\nAbstract: Brick [1] is a recent effort to design a metadata schema for describing building components, subsystems and the relationships between them. With growing interest in Brick, it is important to characterize how suitable Brick is for embedding in real building applications. This demonstration will present HodDB [3], a new database and query processor for Brick models. Attendees will use HodDB to query and explore real Brick models using a variety of textual and graphical query interfaces, and see how HodDB can embed Brick queries in real applications.\",\n \"Title: Hamilton: a cost-effective, low power networked sensor for indoor environment monitoring\\nYear: 2017\\n\\nAbstract: Operating buildings can be challenging, especially with poor instrumentation of the indoor environment. There are several wireless sensor platforms on the market but most are too difficult to deploy en-masse, requiring the end-user to program devices, or manage infrastructure. Many rely on smart-phones and do not work when unattended. The Hamilton wireless sensor node is a full-stack solution providing a low-cost and low-power high-resolution sensor that operates for more than five years on a battery, along with all the cloud infrastructure required to interact with the data. It is pre-programmed and ready to use, but the firmware can be easily modified by using the standard C language.\",\n \"Title: Democratizing authority in the built environment.\\nYear: 2018\\n\\nAbstract: Operating systems and applications in the built environment have relied upon central authorization and management mechanisms that restrict their scalability, especially with respect to administrative overhead. We propose a new set of primitives encompassing syndication, security, and service execution that unifies the management of applications and services across the built environment, while enabling participants to individually delegate privilege across multiple administrative domains with no loss of security or manageability. We show how to leverage a decentralized authorization syndication platform to extend the design of building operating systems beyond the single administrative domain of a building. The authorization system leveraged is based on blockchain smart contracts to permit decentralized and democratized delegation of authorization without central trust. Upon this, a publish/subscribe syndication tier and a containerized service execution environment are constructed. Combined, these mechanisms solve problems of delegation, federation, device protection and service execution that arise throughout the built environment. We leverage a high-fidelity city-scale emulation to verify the scalability of the authorization tier, and briefly describe a prototypical democratized operating system for the built environment using this foundation.\\n\\nThis is an extension of work presented in Ref. [3].\",\n \"Title: System Architecture Directions for Post-SoC/32-bit Networked Sensors.\\nYear: 2018\\n\\nAbstract: The emergence of low-power 32-bit Systems-on-Chip (SoCs), which integrate a 32-bit MCU, radio, and flash, presents an opportunity to re-examine design points and trade-offs at all levels of the system architecture of networked sensors. To this end, we develop a post-SoC/32-bit design point called Hamilton, showing that using integrated components enables a ~$7 core and shifts hardware modularity to design time. We study the interaction between hardware and embedded operating systems, identifying that (1) post-SoC motes provide lower idle current (5.9 μA) than traditional 16-bit motes, (2) 32-bit MCUs are a major energy consumer (e.g., tick increases idle current >50 times), comparable to radios, and (3) thread-based concurrency is viable, requiring only 8.3 μs of context switch time. We design a system architecture, based on a tickless multithreading operating system, with cooperative/adaptive clocking, advanced sensor abstraction, and preemptive packet processing. Its efficient MCU control improves concurrency with ~30% less energy consumption. Together, these developments set the system architecture for networked sensors in a new direction.\",\n \"Title: Bringing Full-Scale TCP to Low-Power Networks.\\nYear: 2018\\n\\nAbstract: Although TCP has widespread adoption in the Internet, wireless sensor networks (WSNs) generally use simpler UDP-based protocols. The few existing TCP implementations for sensor network operating systems do not support all of the features of TCP. We present a full-scale TCP implementation for sensor networks, called TCPlp, based on the TCP protocol logic of the FreeBSD Operating System. Our implementation demonstrates that full-scale TCP can run within the resource constraints of a modern WSN platform, and serves as a vehicle to explore the benefits of using a full TCP stack in the WSN setting. We showcase TCPlp via three applications of TCP: (1) reliable data collection in the context of an application, (2) an interactive configuration/debug shell, and (3) a mote-based web server.\",\n \"Title: MARVEL: Enabling Mobile Augmented Reality with Low Energy and Low Latency.\\nYear: 2018\\n\\nAbstract: This paper presents MARVEL, a mobile augmented reality (MAR) system which provides a notation display service with imperceptible latency (<100 ms) and low energy consumption on regular mobile devices. In contrast to conventional MAR systems, which recognize objects using image-based computations performed in the cloud, MARVEL mainly utilizes a mobile device's local inertial sensors for recognizing and tracking multiple objects, while computing local optical flow and offloading images only when necessary. We propose a system architecture which uses local inertial tracking, local optical flow, and visual tracking in the cloud synergistically. On top of that, we investigate how to minimize the overhead for image computation and offloading. We have implemented and deployed a holistic prototype system in a commercial building and evaluate MARVEL's performance. The efficient use of a mobile device's capabilities lowers latency and energy consumption without sacrificing accuracy.\",\n \"Title: Mortar: an open testbed for portable building analytics.\\nYear: 2018\\n\\nAbstract: Access to large amounts of real-world data has long been a barrier to the development and evaluation of analytics applications for the built environment. Open data sets exist, but they are limited in their span (how much data is available) and context (what kind of data is available and how it is described). Evaluation of such analytics is also limited by how the analytics themselves are implemented, often using hard-coded names of building components, points and locations, or unique input data formats.\\n\\nTo advance the methodology for how such analytics are implemented and evaluated, we present Mortar: an open testbed for portable building analytics, currently spanning 90 buildings and containing over 9.1 billion data points. All buildings in the testbed are described using Brick, a recently developed metadata schema, providing rich functional descriptions of building assets and subsystems. We also propose a simple architecture for writing portable analytics applications that are robust to the diversity of buildings and can configure themselves based on context. We demonstrate the utility of Mortar by implementing 11 applications from the literature.\",\n \"Title: TCPlp: System Design and Analysis of Full-Scale TCP in Low-Power Networks.\\nYear: 2018\\n\\nAbstract: Low power and lossy networks (LLNs) enable diverse applications integrating many embedded devices, often requiring interconnectivity between LLNs and existing TCP/IP networks. However, the sensor network community has been reluctant to adopt TCP, providing only highly simplified TCP implementations on sensor platforms and, instead, developing LLN-specific protocols to provide connectivity. We present a full-scale TCP implementation, based on the TCP protocol logic in FreeBSD, capable of operating over IEEE 802.15.4 within the memory constraints of Cortex-M0+ based platforms. We systematically investigate the behavior of a full-featured TCP implementation in the LLN setting. It provides a 5x to 40x improvement in throughput compared to prior studies. Moreover, we find that TCP is more robust in LLNs than studies of TCP over traditional WLANs would suggest. We empirically demonstrate that, in a lossy environment typical of LLNs, TCP can achieve power consumption comparable to CoAP, a representative LLN-specific reliability protocol. We discuss the potential role of TCP in sensor networks, observing that gateway-free, retransmission-based reliable transport would be an asset to sensor network applications. We conclude that TCP should have a place in the LLN architecture moving forward.\",\n \"Title: A composable framework for secure multi-modal access to internet services from Post-PC devices\\nYear: 2000\\n\\nAbstract: The Post-PC revolution is bringing information access to a wide range of devices beyond the desktop, such as public kiosks, and mobile devices like cellular telephones, PDAs, and voice based vehicle telematics. However, existing deployed Internet services are geared toward the secure rich interface of private desktop computers. We propose the use of an infrastructure-based secure proxy architecture to bridge the gap between the capabilities of Post-PC devices and the requirements of Internet services. By combining generic content and security transformation functions with service-specific rules, the architecture decouples device capabilities from service requirements and simplifies the addition of new devices and services. Security and protocol specifics are abstracted into reusable components. Additionally, the architecture offers the novel ability to deal with untrusted public Internet access points by providing fine-grain control over the content and functionality exposed to the end device, as well as support for using trusted and untrusted devices in tandem. Adding support for a deployed Internet service requires a few hundred lines of scraping scripts. Similarly, adding support for a new device requires a few hundred lines of stylesheets for the device format. The average latency added by proxy transformations is around three seconds in our unoptimized Java implementation.\",\n \"Title: Design and analysis of a query processor for brick.\\nYear: 2018\\n\\nAbstract: Brick is a recently proposed metadata schema and ontology for describing building components and the relationships between them. It represents buildings as directed labeled graphs using the RDF data model. Using the SPARQL query language, building-agnostic applications query a Brick graph to discover the set of resources and relationships they require to operate. Latency-sensitive applications, such as user interfaces, demand response, and model-predictive control, require fast queries—conventionally less than 100ms.\\n\\nWe benchmark a set of popular open source and commercial SPARQL databases against three real Brick models using seven application queries and find that none of them meet this performance target. This lack of performance can be attributed to design decisions that optimize for queries over large graphs consisting of billions of triples but give poor spatial locality and join performance on the small dense graphs typical of Brick. We present the design and evaluation of HodDB, a RDF/SPARQL database for Brick built over a node-based index structure. HodDB performs Brick queries 3--700× faster than leading SPARQL databases and consistently meets the 100ms threshold, enabling the portability of important latency-sensitive building applications.\\n\\nThis article is an extension of a previously published work [16].\",\n \"Title: Jedi: Many-To-Many End-To-End Encryption And Key Delegation For Iot\\nYear: 2019\\n\\nAbstract: As the Internet of Things (IoT) emerges over the next decade, developing secure communication for IoT devices is of paramount importance. Achieving end-to-end encryption for large-scale IoT systems, like smart buildings or smart cities, is challenging because multiple principals typically interact indirectly via intermediaries, meaning that the recipient of a message is not known in advance. This paper proposes JEDI (Joining Encryption and Delegation for IoT), a many-to-many end-to-end encryption protocol for IoT. JEDI encrypts and signs messages end-to-end, while conforming to the decoupled communication model typical of IoT systems. JEDI's keys support expiry and fine-grained access to data, common in IoT. Furthermore, JEDI allows principals to delegate their keys, restricted in expiry or scope, to other principals, thereby granting access to data and managing access control in a scalable, distributed way. Through careful protocol design and implementation, JEDI can run across the spectrum of IoT devices, including ultra low-power deeply embedded sensors severely constrained in CPU, memory, and energy consumption. We apply JEDI to an existing IoT messaging system and demonstrate that its overhead is modest.\",\n \"Title: Thread/OpenThread: A Compromise in Low-Power Wireless Multihop Network Architecture for the Internet of Things\\nYear: 2019\\n\\nAbstract: Extending an Internet subnet by connecting resource-constrained nodes (e.g., embedded sensors and actuators) over multiple wireless hops is necessary to support the future Internet of Things (IoT). RPL, the IPv6 routing standard for low-power and lossy networks, tried to achieve this goal but has not seen wide adoption in practice. As an alternative, Thread is a recently standardized low-power network protocol for IoT, driven by the Thread group, an industry consortium led by Google/Nest. We provide a comparative analysis of the technical aspects of RPL and Thread based on their specifications, explaining why using Thread, as opposed to RPL, may make sense for the future Internet. Specifically, the fundamental differences between RPL and Thread are their respective scopes and multihop network architectures, which result in Thread's unique design and advantages over RPL. Lastly, we evaluate Thread in an indoor multihop wireless testbed using OpenThread, an official open source implementation of Thread. This work serves as the first analysis of the Thread protocol in academia.\",\n \"Title: Mage: Nearly Zero-Cost Virtual Memory For Secure Computation\\nYear: 2021\\n\\nAbstract: Secure Computation (SC) is a family of cryptographic primitives for computing on encrypted data in single-party and multi-party settings. SC is being increasingly adopted by industry for a variety of applications. A significant obstacle to using SC for practical applications is the memory overhead of the underlying cryptography. We develop MAGE, an execution engine for SC that efficiently runs SC computations that do not fit in memory. We observe that, due to their intended security guarantees, SC schemes are inherently oblivioustheir memory access patterns are independent of the input data. Using this property, MAGE calculates the memory access pattern ahead of time and uses it to produce a memory management plan. This formulation of memory management, which we call memory programming, is a generalization of paging that allows MAGE to provide a highly efficient virtual memory abstraction for SC. MAGE outperforms the OS virtual memory system by up to an order of magnitude, and in many cases, runs SC computations that do not fit in memory at nearly the same speed as if the underlying machines had unbounded physical memory to fit the entire computation.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":102,"string":"102"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":244,"string":"244"}}},{"rowIdx":245,"cells":{"question_id":{"kind":"string","value":"Antonio Bucchiarone"},"question":{"kind":"string","value":"Generate an abstract for the title \"BIKE2WORK: A Shift Towards Sustainable Mobility\" using the following items: 1. Sustainable mobility \n2. Active modes \n3. Commuter-generated traffic \n4. Transportation demand management \n5. Mobility Manager"},"answer":{"kind":"string","value":"Encouraging a shift towards sustainable mobility habits based on active mobility is a key challenge for many cities, since they are increasingly facing problems of traffic congestion, road safety, energy dependency and air pollution. Active modes, as cycling, which are also the least polluting, should be particularly encouraged, especially for local recurrent journeys (i.e., home-to-school, home-to-work). In this context, addressing and mitigating commuter-generated traffic requires engaging public and private stakeholders through new innovative and collaborative approaches that focus not only on supply (e.g., roads and vehicles), but also on transportation demand management. In this paper we propose an approach to home-to-work mobility able to support the company Mobility Manager (MM) acting on the promotion of sustainable mobility and transport demand management by analysing the problems, needs and habits of employees, and trying to orient them towards new sustainable transport habits."},"correct_answer":{"kind":"string","value":"Encouraging a shift towards sustainable mobility habits based on active mobility is a key challenge for many cities, since they are increasingly facing problems of traffic congestion, road safety, energy dependency and air pollution. Active modes, as cycling, which are also the least polluting, should be particularly encouraged, especially for local recurrent journeys (i.e., home-to-school, home-to-work). In this context, addressing and mitigating commuter-generated traffic requires engaging public and private stakeholders through new innovative and collaborative approaches that focus not only on supply (e.g., roads and vehicles), but also on transportation demand management. In this paper we propose an approach to home-to-work mobility able to support the company Mobility Manager (MM) acting on the promotion of sustainable mobility and transport demand management by analysing the problems, needs and habits of employees, and trying to orient them towards new sustainable transport habits."},"documents":{"kind":"list like","value":["Title: A car logistics scenario for context-aware adaptive service-based systems\nYear: 2012\n\nAbstract: We present a logistic scenario, based on the sea port of Bremen, and a context-aware dynamic service-based system to support its operation. We also show how we have used it to evaluate our automated adaptation techniques.","Title: A practical architecture-centric analysis process\nYear: 2006\n\nAbstract: When engineering complex and distributed software and hardware systems (increasingly used in many sectors, such as manufacturing, aerospace, transportation, communication, energy and health-care), dependability has became a must, since failures can have economics consequences and can also endanger human life. Software Architectures (SA) can help improving the overall system dependability, providing a system blueprint that can be validated and that can guide all phases of the system development. Even if much work has been done on this direction, three important topics require major investigation: how different analysis techniques can be integrated together, how results obtained with SA-based analysis can be related to requirements and coding, and how to integrate new methodologies in the industrial software development life-cycle. In this paper we propose an architecture-centric analysis process which allows formal analysis driven by model-based architectural specifications. This analysis process satisfies the industrial requirements, since it is tool supported and based on semi-formal (UML-based) specifications.","Title: A Variable Context Model for Adaptable Service-Based Applications\nYear: 2012\n\nAbstract: Service-based applications SBAs rely on the invocation of services. The use of the service paradigm usually guarantees a high level of flexibility. In fact, applications can be easily reconfigured in order to continuously offer functionalities also in dynamic execution environments. This happens by changing the service selection and their composition. This flexibility can be exploited to design adaptable SBAs able to react to events that could happen during the application lifecycle. The execution flow of adaptable SBAs automatically changes on the basis of the context in which they are executing. The context includes information ranging from the situation in which users access the service-based applications to the status of the components involved in the execution of such applications. In this paper the authors propose a way to use context information to adapt SBAs. In particular, their goal is to discuss the way in which the context should be defined and managed in order to be exploited in the various activities related to the adaptation of service-based applications.","Title: A context-driven adaptation process for service-based applications\nYear: 2010\n\nAbstract: When building service-oriented systems the evolution of requirements and context is the norm rather than the exception. Therefore, it is important to make sure that the system is able to evolve as well without necessarily starting a completely new development process, and possibly on the fly. In this paper we specifically focus on the role of the context in the adaptation activities. For us context has various different facets as it includes information ranging from the situation in which users exploit a service-based application to the conditions under which the component services can be exploited. We elaborate on how and when the context should be defined, exploited, and evolved, and on the impact it has on the various activities related to adaptation of service-based applications. We use a case study to exemplify our first findings on this subject.","Title: On-the-Fly Adaptation of Dynamic Service-Based Systems: Incrementality, Reduction and Reuse.\nYear: 2013\n\nAbstract: On-the-fly adaptation is where adaptation activities are not explicitly represented at design time but are discovered and managed at run time considering all aspect of the execution environments. In this paper we present a comprehensive framework for the on-the-fly adaptation of highly dynamic service-based systems. The framework relies on advanced context-aware adaptation techniques that allow for i) incremental handling of complex adaptation problems by interleaving problem solving and solution execution, ii) reduction in the complexity of each adaptation problem by minimizing the search space according to the specific execution context, and iii) reuse of adaptation solutions by learning from past executions. We evaluate the applicability of the proposed approach on a real world scenario based on the operation of the Bremen sea port.","Title: A Formalisation of Adaptable Pervasive Flows\nYear: 2009\n\nAbstract: Adaptable Pervasive Flows is a novel workflow-based paradigm for the design and execution of pervasive applications, where dynamic workflows situated in the real world are able to modify their execution in order to adapt to changes in their environment. In this paper, we study a formalisation of such flows by means of a formal flow language. More precisely, we define APFoL (Adaptable Pervasive Flow Language) and formalise its textual notation by encoding it in Blite, a formalisation of WS-BPEL. The encoding in Blite equips the language with a formal semantics and enables the use of automated verification techniques. We illustrate the approach with an example of a Warehouse Case Study.","Title: Model-Checking Plus Testing: From Software Architecture Analysis to Code Testing\nYear: 2004\n\nAbstract: Software Model-Checking and Testing are some of the most used techniques to analyze software systems and identify hidden faults. While software model-checking allows for an exhaustive and automatic analysis of the system expressed through a model, software testing is based on a clever selection of \"relevant\" test cases, which may be manually or automatically run over the system. In this paper we analyze how those two analysis techniques may be integrated in a specific context, where a Software Architecture (SA) specification of the system is available, model-checking techniques axe used to validate the SA model conformance with respect to selected properties, while testing techniques are used to validate the implementation conformance to the SA model. The results of this research axe applied to an SDH Telecommunication system architecture designed by Siemens CNX.","Title: Modelling Dynamic Software Architectures using Typed Graph Grammars\nYear: 2008\n\nAbstract: Several recent research efforts have focused on the dynamic aspects of software architectures providing suitable models and techniques for handling the run-time modification of the structure of a system. A large number of heterogeneous proposals for addressing dynamic architectures at many different levels of abstraction have been provided, such as programmable, ad-hoc, self-healing and self-repairing among others. It is then important to have a clear picture of the relations among these proposals by formulating them into a uniform framework and contrasting the different verification aspects that can be reasonably addressed by each proposal. Our work is a contribution in this line. In particular, we map several notions of dynamicity into the same formal framework in order to distill the similarities and differences among them. As a result we explain different styles of architectural dynamisms in term of graph grammars and get some better insights on the kinds of formal properties that can be naturally associated to such different specification styles. We take a simple automotive scenario as a running example to illustrate main ideas.","Title: Graph-Based Design and Analysis of Dynamic Software Architectures\nYear: 2008\n\nAbstract: We illustrate two ways to address the specification, modelling and analysis of dynamic software architectures using: i) ordinary typed graph transformation techniques implemented in Alloy; ii) a process algebraic presentation of graph transformation implemented in Maude. The two approaches are compared by showing how different aspects can be tackled, including representation issues, modelling phases, property specification and analysis.","Title: Web Service Composition Approaches: From Industrial Standards to Formal Methods\nYear: 2007\n\nAbstract: Ensuring dependability and security of Peer-to- Peer (P2P) systems is an intricate task due to the autonomous and volatile nature of peers and the decentralization that characterizes such systems. Dynamic verification provides the means of monitoring ...","Title: A Graph-based Design Framework for Global Computing Systems\nYear: 2009\n\nAbstract: We present a framework for designing and analyzing Global Computing Systems using Dynamic Software Architectures. The framework, called TGG\"A, integrates typed graph grammars and the Alloy modeling language to specify Programmed Dynamic Software Architectures that represent systems that evolve their topology at runtime. We demonstrate the benefits of the framework by applying it to the study of an Automotive Software System.","Title: Design for adaptation of service-based applications: main issues and requirements\nYear: 2009\n\nAbstract: Service-based applications are considered a promising technology since they are able to offer complex and flexible functionalities in widely distributed environments by composing different types of services. These applications have to be adaptable to unforeseen changes in the functionality offered by component services and to their unavailability or decreasing performances. Furthermore, when applications are made available to a high number of potential users, they should also be able to dynamically adapt to the current context of use as well as to specific requirements and needs of the specific users. In order to address these issues, mechanisms that enable adaptation should be introduced in the life-cycle of applications, both in the design and in the runtime phases. In this paper we propose an extension of a basic iterative service-based applications lifecycle with elements able to deal with the adaptation-specific needs. We focus, in particular, on the design phase and suggest a number of design principles and guidelines that are suitable to enable adaptation. We discuss about the effectiveness of the proposed methodology by means of real-world scenarios over various types of service-based applications.","Title: A framework for rule-based dynamic adaptation\nYear: 2010\n\nAbstract: We propose a new approach to dynamic adaptation, based on the combination of adaptation hooks provided by the adaptable application specifying where adaptation can happen, and adaptation rules external to the application, specifying when and how adaptation can be performed. We discuss different design choices that have to be considered when using such an approach, and then we propose a possible solution. We describe the solution in details, we apply it to a sample scenario and we implement it on top of the language Jolie.","Title: Towards an architectural approach for the dynamic and automatic composition of software components\nYear: 2006\n\nAbstract: In a component-based software system the components are specified, designed and implemented with the intention to be reused, and are assembled in various contexts in order to produce a multitude of software systems. However, this ideal scenario is not always the case, e.g., the integration with legacy components. In this context, one main problem in component assembly arises. It is related to the ability to automatically and efficiently (i.e., by reducing the state-explosion phenomenon) synthesize an assembly code for a set of, possibly incompatible, software components. Moreover, this assembly should be able to evolve when things change and to be correct-by-construction, i.e., despite the changes, it always ensures a set of properties of interest. In this paper we propose a Software Architecture (SA) based approach in which architectural analysis and code synthesis are combined together in order to efficiently and correctly assemble a system out of a set of already implemented components. The approach can be equally applied to efficiently manage the whole re-factoring of the system when one or more components needs to be substituted, still maintaining the required properties. The specified and validated system SA is used as starting point for the derivation of adaptors required to correctly replace components in the composed system. The approach is applied and validated over an explanatory example concerning with a \"cooling water pipe\" system.","Title: SOAdapt: A process reference model for developing adaptable service-based applications\nYear: 2012\n\nAbstract: Context: The loose coupling of services and Service-Based Applications (SBAs) have made them the ideal platform for context-based run-time adaptation. There has been a lot of research into implementation techniques for adapting SBAs, without much effort focused on the software process required to guide the adaptation. Objective: This paper aims to bridge that gap by providing an empirically grounded software process model that can be used by software practitioners who want to build adaptable SBAs. The process model will focus only on the adaptation specific issues. Method: The process model presented in this paper is based on data collected through interviews with 10 practitioners occupying various roles within eight different companies. The data was analyzed using qualitative data analysis techniques. We used the output to develop a set of activities, tasks, stakeholders and artifacts that were used to construct the process model. Results: The outcome of the data analysis process was a process model identifying nine sets of adaptation process attributes. These can be used in conjunction with an organisation's existing development life-cycle or another reference life-cycle. Conclusion: The process model developed in this paper provides a solid reference for practitioners who are planning to develop adaptable SBAs. It has advantages over similar approaches in that it focuses on software process rather than the specific adaptation mechanism implementation techniques.","Title: TESTOR: deriving test sequences from model-based specifications\nYear: 2005\n\nAbstract: The dependability analysis of a component-based system may be driven by the components/system implementation or by the model-based specification provided prior to or together with the implementation. In particular, model-based specifications of a component-based system allows to explicitly model the structure and behavior of components and their integration, while model-based testing allows to derive test sequences which can be successively refined into test cases and then run onto the system implementation. Several techniques have been proposed so far to allow model-based testing. However, very few of them show certain characteristics which are peculiar for use in industrial contexts. We here describe TeStor, a TEst Sequence generaTOR algorithm which allows to extract test sequences from both state machine and scenario diagrams. We detail the algorithm, we apply it to a system study and we provide a link to its implementation.","Title: An experience in using a tool for evaluating a large set of natural language requirements\nYear: 2010\n\nAbstract: Requirements analysis is an important phase in a software project. It is often performed in an informal way by specialists who review documents looking for ambiguities, technical inconsistencies and incompleteness. Automatic evaluation of Natural Language (NL) requirements documents has been proposed as a means to improve the quality of the system under development. We show how the tool QuARS Express, introduced in a quality analysis process, is able to manage complex and structured requirement documents containing metadata, and to produce an analysis report rich of categorized information that points out linguistic defects and indications about the writing style of NL requirements. In this paper we report our experience using this tool in the automatic analysis of a large collection of natural language requirements, produced inside the MODCONTROL project.","Title: An architectural approach to the correct and automatic assembly of evolving component-based systems\nYear: 2008\n\nAbstract: Software components are specified, designed and implemented with the intention to be reused, and they are assembled in various contexts in order to produce a multitude of software systems. However, in the practice of software development, this ideal scenario is often unrealistic. This is mainly due to the lack of an automatic and efficient support to predict properties of the assembly code by only assuming a limited knowledge of the properties of single components. Moreover, to make effective the component-based vision, the assembly code should evolve when things change, i.e., the properties guaranteed by the assembly, before a change occurs, must hold also after the change. Glue code synthesis approaches technically permit one to construct an assembly of components that guarantees specific properties but, practically, they may suffer from the state-space explosion phenomenon. In this paper, we propose a Software Architecture (SA) based approach in which the usage of the system SA and of SA verification techniques allows the system assembler to design architectural components whose interaction is verified with respect to the specified properties. By exploiting this validation, the system assembler can perform code synthesis by only focusing on each single architectural component, hence refining it as an assembly of actual components which respect the architectural component observable behaviour. In this way code synthesis is performed locally on each architectural component, instead of globally on the whole system interactions, hence reducing the state-space explosion phenomenon. The approach can be equally well applied to efficiently manage the whole reconfiguration of the system when one or more components need to be updated, still maintaining the required properties. The specified and verified system SA is used as starting point for the derivation of glue adaptors that are required to apply changes in the composed system. The approach is firstly illustrated over an explanatory example and is then applied and validated over a real-world industrial case study.","Title: QoS Composition of Services for Data-Intensive Application\nYear: 2007\n\nAbstract: Ensuring dependability and security of Peer-to- Peer (P2P) systems is an intricate task due to the autonomous and volatile nature of peers and the decentralization that characterizes such systems. Dynamic verification provides the means of monitoring ...","Title: Formal analysis and verification of self-healing systems\nYear: 2010\n\nAbstract: Self-healing (SH-)systems are characterized by an automatic discovery of system failures, and techniques how to recover from these situations. In this paper, we show how to model SH-systems using algebraic graph transformation. These systems are modeled as typed graph grammars enriched with graph constraints. This allows not only for formal modeling of consistency and operational properties, but also for their analysis and verification using the tool AGG. We present sufficient static conditions for self-healing properties, deadlock-freeness and liveness of SH-systems. The overall approach is applied to a traffic light system case study, where the corresponding properties are verified.","Title: Adaptation of service-based business processes by context-aware replanning\nYear: 2011\n\nAbstract: Service-based business processes are typically used by organizations to achieve business goals through the coordinated execution of a set of activities implemented as services and service compositions. Since they are executed in dynamic, open and non-deterministic environments, business processes often need to be adapted to exogenous context changes and execution problems. In this paper we provide an adaptation approach that can automatically adapt business processes to run-time context changes that impede achievement of a business goal. We define a formal framework that adopts planning techniques to automatically derive necessary adaptation activities on demand. The adaptation consists in identifying recovery activities that guarantee that the execution of a business process can be successfully resumed and, as a consequence, the business goals are achieved. The solution proposed is evaluated on a real-world scenario from the logistics domain.","Title: Automatic synthesis of coordinators for COTS group-ware applications: an example\nYear: 2003\n\nAbstract: The coordination of concurrent activities in collaborativeenvironments is a very important and difficult task.Many approaches for the construction of large-scale flexiblegroup-ware applications there exist in the literature. Theyprovide valid support to modelling, analysis and to a white-boxdeveloping of coordination protocols for computer supportedcooperative applications. Little attention has beendedicated so far to group-ware applications built by assemblingthird-party components. In this paper by means ofan explanatory example, we apply a software architecturebased approach to the group-ware systems development.The software architecture imposed on the coordinating partof the system, allows for detection and recovery of possibleand unpredictable concurrent activities conflicts. Moreover,the approach allows the enforcing of coordination policieson the composed system by automatically synthesizing thepolicy-satisfying assembly code.","Title: Dynamic Software Architecture Development: Towards an Automated Process\nYear: 2009\n\nAbstract: We propose a software engineering process to aid the development of Dynamic Software Architectures (DSAs). This process is based on the sequential application of a number of formal methods and tools, and it can support software architects throughout the design, analysis and code generation of software systems. To illustrate the process, we apply it to an industrial case study from the Service Oriented Computing (SOC) domain.","Title: ASTRO-CAptEvo: Dynamic Context-Aware Adaptation for Service-Based Systems\nYear: 2012\n\nAbstract: Adaptivity is a key feature of service-based systems to fully exploit the advantages offered by the service paradigm. In this paper we present a comprehensive framework that can be used to define and support highly adaptable context-aware service-based business processes. In our approach, all the adaptation-related tasks, from detecting an adaptation problem to finding a solution and applying it to a running process instance, are performed automatically at run time. We also show how the framework has been implemented and applied to a real-world scenario from the logistics domain.","Title: Domain Objects for Continuous Context-Aware Adaptation of Service-Based Systems\nYear: 2013\n\nAbstract: The idea to build systems based on services, by reusing and combining software made available independently via different technologies and channels and dynamically organizing them into coherent processes, has a very well recognized potential. Achieving this potential stands crucially on the ability to recognize and exploit the context in which such applications operate, in terms of the available services, of the actual setup at run-time, and of the interaction with human actors. Changing contexts require run-time reaction, by adapting the ongoing overall process enacted by the service-based system to unexpected deviations. Continuous context-aware adaptation is hencefore a strong requirement in this setting. In this paper, we propose a service delivery platform designed for the continuous context-aware adaptation of service-based systems, based on the idea of monitoring the underlying context via a hierarchical model, and using the context to drive the choice and execution of adaptive pervasive flows. We describe the approach through an example from the smart cities e-mobility domain.","Title: Dynamic Adaptation of Fragment-Based and Context-Aware Business Processes\nYear: 2012\n\nAbstract: We propose a comprehensive framework for adaptivity of service-based applications, which exploits the concept of process fragments as a way to model reusable process knowledge and to allow for the dynamic, incremental, context- aware composition of such fragments into adaptable service-based applications. The framework provides a set of adaptation mechanisms that, combined through adaptation strategies, are able to solve complex adaptation problems. An implementation of the proposed solution is presented and evaluated on a real world scenario from the logistics domain.","Title: CAptEvo: context-aware adaptation and evolution of business processes\nYear: 2011\n\nAbstract: CAptEvo is a framework for the adaptation and evolution of service-based business processes operating in dynamic execution environments. In this demonstration, we apply the CAptEvo to a case study from the logistics domain and show its advantages in handling highly complex dynamic real-world business applications.","Title: Architecting Fault-tolerant Component-based Systems: from requirements to testing\nYear: 2007\n\nAbstract: Fault tolerance is one of the most important means to avoid service failure in the presence of faults, so to guarantee they will not interrupt the service delivery. Software testing, instead, is one of the major fault removal techniques, realized in order to detect and remove software faults during software development so that they will not be present in the final product. This paper shows how fault tolerance and testing can be used to validate component-based systems. Fault tolerance requirements guide the construction of a fault-tolerant architecture, which is successively validated with respect to requirements and submitted to testing. The theory is applied over a mining control system running example.","Title: Using a Lifecycle Model for Developing and Executing Adaptable Interactive Distributed Applications\nYear: 2010\n\nAbstract: We describe a case study on using the generic Lifecycle Model developed in the S-Cube project for a novel class of Real-time Online Interactive Applications (ROIA), which include distributed simulations (e.g. massively-multiplayer online games), e-learning and training. We describe how the Lifecycle Model supports application development by addressing the specific challenges of ROIA: a large number of concurrent users connected to a single application instance, frequent real-time user interactions, enforcement of Quality of Service (QoS) parameters, adaptivity to changing loads, and competition-oriented interaction between users, other actors, and services. We describe the implementation aspects of the application development and adaptation using the RTF (Real-Time Framework) middleware, and report experimental results for a sample online game application.","Title: An architecture-centric approach for producing quality systems\nYear: 2005\n\nAbstract: Software architecture has been advocated as an effective means to produce quality systems. In this paper, we argue that integration between analysis conducted at different stages of development is still lacking. Hence we propose an architecture-centric approach which, by combining different technologies and tools for analysis and testing, supports a seamless tool-supported approach to validate required properties. The idea is to start from the requirements, produce a validated model of the SA, and then use the SA to derive a set of conformance test cases. In this paper, we outline the process, and discuss how some existing tools, namely QuARS,ModTest, CowTest and UIT, could be exploited to support the approach. The integrated framework is under development.","Title: From Requirements to code: an Architecture-centric Approach for producing Quality Systems\nYear: 2009\n\nAbstract: When engineering complex and distributed software and hardware systems\n(increasingly used in many sectors, such as manufacturing, aerospace,\ntransportation, communication, energy, and health-care), quality has become a\nbig issue, since failures can have economics consequences and can also endanger\nhuman life. Model-based specifications of a component-based system permit to\nexplicitly model the structure and behaviour of components and their\nintegration. In particular Software Architectures (SA) has been advocated as an\neffective means to produce quality systems. In this chapter by combining\ndifferent technologies and tools for analysis and development, we propose an\narchitecture-centric model-driven approach to validate required properties and\nto generate the system code. Functional requirements are elicited and used for\nidentifying expected properties the architecture shall express. The\narchitectural compliance to the properties is formally demonstrated, and the\nproduced architectural model is used to automatically generate the Java code.\nSuitable transformations assure that the code is conforming to both structural\nand behavioural SA constraints. This chapter describes the process and\ndiscusses how some existing tools and languages can be exploited to support the\napproach.","Title: Dynamic Software Architectures Verification using DynAlloy\nYear: 2008\n\nAbstract: Graph Grammars have been often used for modeling dynamic changes in software architectures. In particular, we have previously characterized some classes of dynamicity in terms of particular aspects of graph grammars. Moreover we have identified classes of properties that can be naturally associated to any of such kinds of dynamicities. In this paper we approach the problem of verifying such prop- erties over graph grammars specifications. In particular, we use DYNALLOY for attempting this task and we have concentrated on proving properties associated to a particular programmable dynamic software architecture.","Title: Evaluation Of Natural Language Requirements In The Modcontrol Project\nYear: 2008\n\nAbstract: We describe QuARS (Quality Analyzer for Requirement Specifications) Express, a customized version of the QuARS tool. It is designed to evaluate natural language requirements, can handle complex and structured data formats containing metadata, and is able to produce an analysis report with categorized information.","Title: A Context-Aware Framework for Business Processes Evolution\nYear: 2011\n\nAbstract: Run-time adaptability is a key feature of dynamic business environments, where the processes need to be constantly refined and restructured to deal with exceptional situations and changing requirements. The execution of such a system results in a set of adapted process variants instantiated on the same process model but dynamically restructured to handle specific contexts. Process evolution exploits the information on process variants to identify the best performing recurring adaptations and adopt them as general solutions in the process model. However, process variants are strictly related to specific execution contexts and cannot be adopted as general solutions. We propose a framework supporting context-aware evolution of business processes based on process instance execution and adaptation history. Instead of looking for recurring adaptations, we propose to look for recurring adaptation needs (i.e., process instances with the same context constraint violation and system configuration). Based on the analysis of adapted instances, we automatically construct and rank corrective evolution variants which can handle the problematic context. At the same time, we try to identify preventive evolution variants by constructing process variants which can prevent the adaptation need. We demonstrate the benefits of our approach using a car logistics scenario.","Title: Towards Modeling and Execution of Collective Adaptive Systems.\nYear: 2013\n\nAbstract: Collective Adaptive Systems comprise large numbers of heterogeneous entities that can join and leave the system at any time depending on their own objectives. In the scope of pervasive computing, both physical and virtual entities may exist, e. g., buses and their passengers using mobile devices, as well as citywide traffic coordination systems. In this paper we introduce a novel conceptual framework that enables Collective Adaptive Systems based on well-founded and widely accepted paradigms and technologies like service orientation, distributed systems, context-aware computing and adaptation of composite systems. Toward achieving this goal, we also present an architecture that underpins the envisioned framework, discuss the current state of our implementation effort, and we outline the open issues and challenges in the field.","Title: Adaptivity in dynamic service-based systems\nYear: 2012\n\nAbstract: Adaptivity for service-based systems is one of the most challenging research problems to fully exploit the dinamicity promised by the service paradigm. In this paper we present the research results achieved by the FBK SOA unit within the S-Cube Network, aiming at addressing key challenges in this area: context-aware adaptation, user-centric adaptation, cross- and multi-layer adaptation.","Title: Domain Objects for Dynamic and Incremental Service Composition.\nYear: 2014\n\nAbstract: A key feature of service-based applications (SBAs) is the capacity to dynamically define the composition of services independently available, which is required to achieve user goals. For this reason, to effectively deal with the obstacles due to continuous context changes, an incremental refinement of provided services is needed. We propose a new model that allows service functionalities to be defined partially, through the use of abstract activities. The refinement of these activities is postponed and performed incrementally at runtime, using the actual context as a guide. Our approach lets a service provider avoid the hard-coding of all service functionalities and their possible compositions at design time, delaying their refinement until the execution phase. Consequently the whole SBA's design becomes modular and flexible to better meet the typical dynamism of SBA. We illustrate the approach through an example scenario from the urban mobility domain.","Title: Research challenges on multi-layer and mixed-initiative monitoring and adaptation for service-based systems\nYear: 2012\n\nAbstract: Adaptation of complex service-based systems is one of the most challenging research problems for the Future Internet. A considerable effort has been dedicated in recent years to address this problem. However, there are still several important issues that call for concrete solutions. In this paper, we present a set of research challenges for muti-layer and mixed-initiative adaptation and monitoring that may guide the research in this area for the next 5-10 years.","Title: A Goal Model for Collective Adaptive Systems\nYear: 2014\n\nAbstract: A collective adaptive system is composed of large numbers of autonomous and self-adaptive entities which are able to provide benefits for other participants and have to cooperate with each other to accomplish their individual goals. When entities adapt their own behaviour due to unexpected situations, this may result in breaking the overall collaboration if these are not executed simultaneously and do not respect some collective constraints. The objective of this paper is to present a goal model that allows to express requirements for collective adaptability. It includes (i) how to specify the behaviour of the entities that encodes cooperation with other entities, (ii) how to link collaborative goals and individual goals, and (iii) how to specify constraints that are imposed on different entities to preserve some form of collective consistency while they are adapted.","Title: Self-Repairing systems modeling and verification using AGG\nYear: 2009\n\nAbstract: Self-repairing (or healing) systems are systems equipped with a mechanism that monitors the system behaviour to determine whether it behaves within prefixed parameters. If a deviation exists, then the system itself is in charge of adapting its configuration. In this paper we show how to model self-repairing systems by means of dynamic software architectures (DSAs). DSAs are formalized as typed (hyper) graph grammars (TGGs) and this formalization enables verification of correctness and completeness of self-repairing systems. DSAs are modeled and verified by using the attributed graph grammar system (AGG). The overall approach is applied to a traffic light system case study.","Title: All Together Now: Collective Intelligence for Computer-Supported Collective Action\nYear: 2015\n\nAbstract: In this position paper, we argue that a new methodological paradigm and software platform is required for developing citizen-oriented social computing applications. The platform that we propose is based on the idea of 'Collective Intelligence as a Service', and is grounded in the formalisation of computational models derived from an empirical analysis of psychological processes and social practices. This in turn provides the enablers for developing radically innovative tools for computational sustainability and computer-supported collective action in smart communities (e.g. Smart cities). Our vision is illustrated with two exemplars, one a healthcare application for patients with peripheral arterial disease, and the other an application for collaborative energy conservation to meet targets set out in a city's Sustainable Energy Action Plan.","Title: An Approach for Collective Adaptation in Socio-Technical Systems\nYear: 2015\n\nAbstract: Socio-technical systems are systems where autonomous humans and computational entities collectively collaborate with each other to satisfy their goals in a dynamic environment. To be resilient, such systems need to adapt to unexpected human behaviours and exogenous changes in the environment. In this paper, we describe a framework for the development of social-technical systems where adaptation is itself a collective process driven by the awareness of capabilities, goals, constraints and preferences of humans and entities, and knowledge of the environment. The adaptation is controlled by a multi-criteria decision making function combined with an analytic hierarchic process (AHP). We present our approach, the collective adaptation algorithm, and its application to a smart mobility scenario.","Title: Sustainable Safety in Mobile Multi-robot Systems via Collective Adaptation\nYear: 2015\n\nAbstract: To be safe, mobile multi-robots systems need to be able to adapt to unexpected behaviours of robots as well as to exogenous changes in the environment. In this paper, we describe a novel approach for the development of multi-robots systems where robots collectively collaborate with each other to satisfy their goals and to adapt their behaviour in a collective way satisfying the overall system safety. Safety-specific self-adaptation capabilities of the approach are generic and independent from the functional behaviour of the robots. An example dealing with safety for autonomous UAV is provided as well.","Title: Design for Adaptation of Distributed Service-Based Systems.\nYear: 2015\n\nAbstract: Internet of Services applications need to cope with a continuously changing environment, both in terms of the context in which they operate, and of the services, users and providers involved. In this setting, adaptivity is to be considered an intrinsic characteristic of applications rather than an exception to be handled. In this paper we propose a design for adaptation approach that fully exploits the advantages of the service-oriented paradigm to support the development and operation of service-based applications operating in highly dynamic environments. The approach is based on dynamic and incremental service composition and re-configuration techniques and is evaluated on a real-world scenario in the Smart Cities domain.","Title: Distributed Service Co-evolution Based on Domain Objects.\nYear: 2015\n\nAbstract: Service evolution is a critical ingredient of the service lifecycle. The more our society depends on large-scale, complex service environments including cloud and mobile services, the more pressing becomes the question of how to evolve a service on the fly at runtime, without bringing whole systems to a halt, due to unintended percolation of evolution effects through service inter-dependency chains. Thus, there is an urgent need for coordinated service evolution (co-evolution). This paper contributes a conceptual solution for dynamic, on-the-fly co-evolution of services, as well as a framework that supports the engineering of such co-evolution support. Our solution is built on top of the Domain Objects architectural concept and service-oriented computing model. We also analyze the types of changes that might happen in a service and their potential impact on dependent clients and servers, and discuss the benefits of our approach on those service co-evolution scenarios.","Title: Preface to DAS 2016\nYear: 2016\n\nAbstract: Presents the introductory welcome message from the conference proceedings. May include the conference officers' congratulations to all involved with the conference event and publication of the proceedings record.","Title: Incremental Composition for Adaptive By-Design Service Based Systems\nYear: 2016\n\nAbstract: A key challenge posed by the Internet of Services is that applications need to cope with a continuously changing environment, both in terms of the context in which they operate and of the services, users and providers involved. Differently from applications where traditional change detection and adaptation mechanisms can be used, the Internet of Services requires systems that are adaptive by design. In this paper we present a design for adaptation framework supporting the modeling, development and operation of service based applications operating in highly dynamic environments. The approach exploits advanced techniques for dynamic and incremental service composition, allowing to effectively deal with changes occurring at different levels in the system. An implementation of the proposed solution is presented and evaluated on a real-world scenario from the Smart Urban Mobility domain.","Title: SMART: A process-oriented methodology for resilient smart cities.\nYear: 2016\n\nAbstract: Cities are engines of economic prosperity and social development. Rapid urbanization and the impacts of climate change have resulted in increased vulnerabilities in cities. On the other hand, the increasing proliferation of connected devices and distributed monitoring of the environment around us has opened up an opportunity to transform the way we create and manage cities. Contextual evidence of performance, outcome and efficiency can now be readily collected at a higher resolution to aid multi-disciplinary and multi-objective decision-making, enabling optimal evolution of cities against the backdrop of constrained resources and intensified vulnerabilities. This paper first argues that distributed and ubiquitous monitoring is at the heart of smart cities. Insights can be inferred from the gathered data with potential for evidence-based decisions at the required spatial and temporal scales. The paper then discusses the development of a comprehensive but concise frameworks called DICES (data, insights, citizen, evidence and standards) for conceptualizing smart cities. The dimensions of DICES are then translated into a process oriented methodology called SMART (specify, monitor, analyze, resolve and transform) by formalizing key aspects of the smart city process. Generality and scalability of DICES and SMART are demonstrated through the development of REPRO, a risk- and evidence-based platform for resilient and optimal design of buildings and infrastructure in a smart city.","Title: Leveraging Collective Run-Time Adaptation for UAV-Based Systems\nYear: 2016\n\nAbstract: UAV-based systems are systems that are composed of a team of drones, various devices (like movable cameras, sensors), and human agents, which collaborate each other to accomplish defined missions. Since humans are constituent part of these systems, UAV-based systems are both mission-critical and safety-critical. Moreover, these systems are requested to operate in potentially unpredictable and unknown environments. A model of the environment describing, e.g. obstacles, no-fly zones, wind and weather conditions might be available, however, the assumption that such model is both correct and complete is often wrong. In this paper, we describe a novel approach for managing the run-time adaptation of UAV-based systems. Our approach is based on a generic collective adaptation engine that addresses collective adaptation problems in a decentralized fashion, operates at run-time, and enables the addition of new entities at any time. Moreover, our approach dynamically understands which parts of the system should be selected to solve an adaptation issue. The feasibility and scalability of the approach have been empirically evaluated in the context of a private company surveillance scenario.","Title: A context-aware framework for dynamic composition of process fragments in the internet of services.\nYear: 2017\n\nAbstract: In the last decade, many approaches to automated service composition have been proposed. However, most of them do not fully exploit the opportunities offered by the Internet of Services (IoS). In this article, we focus on the dynamicity of the execution environment, that is, any change occurring at run-time that might affect the system, such as changes in service availability, service behavior, or characteristics of the execution context. We indicate that any IoS-based application strongly requires a composition framework that supports for the automation of all the phases of the composition life cycle, from requirements derivation, to synthesis, deployment and execution. Our solution to this ambitious problem is an AI planning-based composition framework that features abstract composition requirements and context-awareness. In the proposed approach most human-dependent tasks can be accomplished at design time and the few human intervention required at run time do not affect the system execution. To demonstrate our approach in action and evaluate it, we exploit the ASTRO-CAptEvo framework, simulating the operation of a fully automated IoS-based car logistics scenario in the Bremerhaven harbor.","Title: Combining Self-Organisation and Autonomic Computing in CASs with Aggregate-MAPE\nYear: 2016\n\nAbstract: Aggregate computing is a recently proposed framework to build CASs (collective adaptive systems) by focussing on direct programming of ensembles so as to abstract away from individual devices and their single interaction acts: this approach is shown to streamline the identification of highly reusable block components, and support reasoning about their resiliency properties. Following this paradigm, in this paper we present a framework for bridging the gap between the MAPE (Monitor-Analyse-Plan-Execute) loop of autonomic computing managers, and fully-distributed self-organising CASs. This is achieved by seeing the collection of M components of each agent as an aggregate, amenable to a direct specification as overall CAS Monitoring behaviour, and similarly for A, P and E. As a result, a self-organising CAS can be programmed by clearly separating the M, A, P, and E parts of it, though each is expressed in terms of a collective behaviour. The proposed approach is exemplified with an application scenario of crowd dispersal in a large-scale smart-mobility application.","Title: Towards learning domain-independent planning heuristics.\nYear: 2017\n\nAbstract: Automated planning remains one of the most general paradigms in Artificial Intelligence, providing means of solving problems coming from a wide variety of domains. One of the key factors restricting the applicability of planning is its computational complexity resulting from exponentially large search spaces. Heuristic approaches are necessary to solve all but the simplest problems. In this work, we explore the possibility of obtaining domain-independent heuristic functions using machine learning. This is a part of a wider research program whose objective is to improve practical applicability of planning in systems for which the planning domains evolve at run time. The challenge is therefore the learning of (corrections of) domain-independent heuristics that can be reused across different planning domains.","Title: DeMOCAS: Domain Objects for Service-Based Collective Adaptive Systems.\nYear: 2016\n\nAbstract: DeMOCAS is a framework for the modeling and execution of service-based collective adaptive systems operating in dynamic environments. In this framework, we apply the Domain Object model and a Collective Adaptation algorithm to a case study from the mobility domain and we show its advantages in handling large-scale, decentralized and adaptive applications.","Title: Decentralized Dynamic Adaptation for Service-Based Collective Adaptive Systems.\nYear: 2016\n\nAbstract: Modern service-based systems are progressively becoming more heterogeneous. They form a socio-technical system, composed of distributed entities, software and human participants, interacting with and within the environment. These systems operate under constant perturbations that are due to unexpected changes in the environment and to the unpredictable behavior of the participants. We argue that for a service-based system to be resilient, adaptation must be collective. Multiple participants must adapt their behavior in concert to respond to critical runtime impediments. In this work, we present a framework for the modeling and execution of large-scale service-based Collective Adaptive Systems, where adaptation needs are solved in a decentralized and collective manner.","Title: Towards a Domain Specific Language for Engineering Collective Adaptive Systems\nYear: 2017\n\nAbstract: Heterogeneous agents that cooperate to accomplish collective tasks constitute Collective Adaptive Systems (CAS). Engineering a CAS not only involves the definition of the individual agents, but also their roles in achieving a collective task and adaptation strategies to counteract to environmental changes. Current solutions for specifying CAS typically tackle the problem at a low level of abstraction (e.g., writing XML files), making this task time-consuming and error-prone. Moreover, such a low level of abstraction hinders the understandability of the specification. Model-Driven Engineering (MDE) proposes to reduce the complexity of development by adopting models as first class artifacts in the process. In this respect, this work proposes a MDE approach to enhance CAS specification. In particular, we introduce a domain-specific language (DSL) made-up of three main views: one devoted to adaptive systems design; one addressing ensembles definition; and one tackling the collective adaptation. These three separate aspects are woven seamlessly by the DSL to constitute a complete CAS design. While the different views allow us to exploit separation-of-concerns to reduce complexity and focus on a specific aspect of the system, facing CAS specification at a higher-level of abstraction permits to use concepts closer to the experts of the involved domains. Moreover, the precise definition of modeling concepts through corresponding meta-models enables correctness-by-construction of the system specification.","Title: CAStlE: A Tool for Collective Adaptive Systems Engineering\nYear: 2017\n\nAbstract: In this paper we propose CAStlE, a MDE approach to enhance Collective Adaptive System (CAS) specification. In particular, we introduce a domain-specific language (DSL) made-up of three main views: one devoted to adaptive systems design; one addressing ensembles definition; and one tackling the collective adaptation. These three separate aspects are woven seamlessly by the DSL to constitute a complete CAS design. Moreover, each of the defined views conveys the creation of a corresponding model editor, which allows for the three aspects of a CAS to be independently designed by CAStlE.","Title: Domain Objects and Microservices for Systems Development: a roadmap.\nYear: 2016\n\nAbstract: This paper discusses a roadmap to investigate Domain Objects being an adequate formalism to capture the peculiarity of microservice architecture, and to support Software development since the early stages. It provides a survey of both Microservices and Domain Objects, and it discusses plans and reflections on how to investigate whether a modeling approach suited to adaptable service- based components can also be applied with success to the microservice scenario.","Title: From Monolithic to Microservices: An Experience Report from the Banking Domain.\nYear: 2018\n\nAbstract: Microservices have seen their popularity blossoming with an explosion of concrete applications in real-life software. Several companies are currently involved in a major refactoring of their back-end systems in order to improve scalability. This article presents an experience report of a real-world case study, from the banking domain, in order to demonstrate how scalability is positively affected ...","Title: Collective Adaptation Through Concurrent Planning: The Case Of Sustainable Urban Mobility\nYear: 2018\n\nAbstract: In this paper we address the challenges that impede collective adaptation in smart mobility systems by proposing a notion of ensembles. Ensembles enable systems with collective adaptability to be built as emergent aggregations of autonomous and self-adaptive agents. Adaptation in these systems is triggered by a run-time occurrence, which is known as an issue. The novel aspect of our approach is, it allows agents affected by an issue in the context of a smart mobility scenario to adapt collaboratively with minimal impact on their own preferences through an issue resolution process based on concurrent planning algorithms.","Title: Carpool: Collective Adaptation Using Concurrent Planning\nYear: 2018\n\nAbstract: In this paper we present the CARPooL demonstrator, an implementation of a Collective Adaptation Engine (CAE) that addresses the challenge of collective adaptation in the smart mobility domain. CARPooL resolves adaptation issues via concurrent planning techniques. It also allows to interact with the provided solutions by adding new issues or analyzing the actions done by each agent.","Title: Enacting Emergent Configurations in the IoT Through Domain Objects.\nYear: 2018\n\nAbstract: The Internet of Things (IoT) pervades more and more aspects of our lives and often involves many types of smart connected objects and devices. User’s IoT environment changes dynamically, e.g., due to the mobility of the user and devices. Users can fully benefit from the IoT only when they can effortlessly interact with it. To accomplish this in a dynamic and heterogenous environment, we make use of Emergent Configurations (ECs), which consist of a set of things that connect and cooperate temporarily through their functionalities, applications, and services, to achieve a user goal. In this paper, we: (i) present the IoT-FED architectural approach to enable the automated formation and enactment of ECs. IoT-FED exploits heterogeneous and independently developed things, IoT services, and applications which are modeled as Domain Objects (DOs), a service-based formalism. Additionally, we (ii) discuss the prototype we developed and the experiments run in our IoT lab, for validation purposes.","Title: Using a lifecycle model for developing and executing real-time online applications on clouds\nYear: 2011\n\nAbstract: We describe how the generic Lifecycle Model developed in the S-Cube project for the design and management of service-based applications (SBA) can be utilized in the context of Cloud Computing. In particular, we focus on the fact that the Infrastructure-as-a-Service approach enables the development of Real-Time Online Interactive Applications (ROIA), which include multi-player online computer games, interactive e-learning and training applications and high-performance simulations in virtual environments. We illustrate how the Lifecycle Model expresses the major design and execution aspects of ROIA on Clouds by addressing the specific characteristics of ROIA: a large number of concurrent users connected to a single application instance, enforcement of Quality of Service (QoS) parameters, adaptivity to changing loads, and frequent real-time interactions between users and services. We describe how our novel resource management system RTF-RMS implements concrete mechanisms that support the developer in designing adaptable ROIA on Clouds according to the different phases of the Lifecycle Model. Our experimental results demonstrate the influence of the proposed adaptation mechanisms on the application performance.","Title: ATLAS: A World-Wide Travel Assistant Exploiting Service-Based Adaptive Technologies.\nYear: 2017\n\nAbstract: Nowadays, users can count on a large amount of mobility services offering disparate functionalities and providing all needed information. Yet, from a user perspective, properly exploiting the available mobility services to organize journeys meeting personal expectations, is becoming a complex task. Indeed, discover and select the appropriate services in an open and constantly expanding domain, is a challenging and time-consuming task. We claim that a uniform and easy way for exploiting these services while moving around, getting accurate and personalized information is still missing. In this paper we propose a platform for the definition of value-added mobility services by (i) enhancing interoperability among the existing services, (ii) supporting their execution via run-time adaptation, (iii) through the definition of multi-channel front-end applications. On top of the platform, we have implemented and evaluated a world-wide travel assistant.","Title: Cyber-Storms Come from Clouds: Security of Cloud Computing in the IoT Era.\nYear: 2019\n\nAbstract: The Internet of Things (IoT) is rapidly changing our society to a world where every thing is connected to the Internet, making computing pervasive like never before. This tsunami of connectivity and data collection relies more and more on the Cloud, where data analytics and intelligence actually reside. Cloud computing has indeed revolutionized the way computational resources and services can be used and accessed, implementing the concept of utility computing whose advantages are undeniable for every business. However, despite the benefits in terms of flexibility, economic savings, and support of new services, its widespread adoption is hindered by the security issues arising with its usage. From a security perspective, the technological revolution introduced by IoT and Cloud computing can represent a disaster, as each object might become inherently remotely hackable and, as a consequence, controllable by malicious actors. While the literature mostly focuses on the security of IoT and Cloud computing as separate entities, in this article we provide an up-to-date and well-structured survey of the security issues of cloud computing in the IoT era. We give a clear picture of where security issues occur and what their potential impact is. As a result, we claim that it is not enough to secure IoT devices, as cyber-storms come from Clouds.","Title: The Resilience of \"Planes, Trains, and Automobiles\": Comment on \"Driverless Cars Will Make Passenger Rail Obsolete, \" by Yair Wiseman [Opinion].\nYear: 2019\n\nAbstract: Reports on transportation systems in smart cities. Modern cities are complex socio-technical entities that exist to provide services effectively to their residents and visitors. In the mobility context, people need to travel quickly and conveniently between locations at different scales, ranging from a trip of a few blocks to a journey across town or further. Each trip has its set of requirements....","Title: Microservices: Migration of a Mission Critical System\nYear: 2021\n\nAbstract: An increasing interest is growing around the idea of microservices and the promise of improving scalability when compared to monolithic systems. Several companies are evaluating pros and cons of a complex migration. In particular, financial institutions are positioned in a difficult situation due to the economic climate and the appearance of agile competitors that can navigate in a more flexible l...","Title: Preface of the 15th International Workshop on Models@run.time’21\nYear: 2021\n\nAbstract: After a break in 2020, this year the 15th edition of the workshop Models@run.time is held at the 24th International Conference on Model Driven Engineering Languages and Systems. The workshop takes place virtually due to the Covid-19 pandemic on the 11th of October 2021. The workshop is organized by Sebastian Götz, Antonio Bucchiarone and Nelly Bencomo. Here, we present some highlights of the works...","Title: POLYGLOT for Gamified Education: Mixing Modelling and Programming Exercises\nYear: 2021\n\nAbstract: Gamification refers to the employment of gaming mechanisms for non-gaming purposes. Its aim is promoting the engagement of target users in pursuing certain goals, e.g. completing education paths. In this paper we present POLYGLOT, a gamified notebook-like programming environment. The gamification extension was built to target programming languages education, and in this work we illustrate how the ...","Title: How to merge gamification efforts for programming and modelling: a tool implementation perspective\nYear: 2021\n\nAbstract: Gamification, that is the use of gaming elements into non-game contexts, has gained a lot of interests in all those settings where the engagement of target users needs to be stimulated. Education and training have been historically struggling with keeping \"students\" motivated to pursue the completion of their learning paths. Lately these issues have been exacerbated by distance education: on the one hand, virtual participation to courses makes education far more accessible than requiring students to seat in the same classroom (and at the same time); on the other hand, the missing \"community building\" conveyed by physically attending the same course remarkably reduces students' engagement. In this respect, gamification has been applied as an engagement tool, e.g. in programming courses, by introducing challenges, awards, leader boards, and so forth, with the aim of motivating the students in keeping their efforts for completing their studies. In this paper we describe and compare our experiences in gamification solutions for programming and modelling. In particular, we distinguish some desirable features to have in gamification solutions for modelling courses, and illustrate our experiences in realizing them concretely. Our observations testify that while in principle many of the gamification elements coming from programming courses could be suitable also to engage students in modelling, there exist still remarkable obstacles in realizing them in practice.","Title: Towards a Framework to Assist Iterative and Adaptive Design in Gameful Systems\nYear: 2021\n\nAbstract: Over the years, gamification gained consensus among researchers and practitioners as a tool to motivate people to perform activities deemed as tedious or unexciting. Hence, there exist many and heterogeneous application domains that may benefit from gamification. However, the domain expert and the designer are often separate individuals with dissimilar backgrounds, skills, and understanding. Thus,...","Title: MeetDurian: Can Location-Based Games be Used to Improve COVID-19 Hygiene Habits?\nYear: 2022\n\nAbstract: The COVID-19 problem has not gone away with the passing of the seasons. Although most countries have achieved remarkable results in fighting against epidemic diseases and controlling viruses, the general public is still far from understanding the new crown virus and lack imagination on its transmission law. Location-based games (LBGs) have been challenged during the on-going pandemic. No research has shown that LBGs can be used to help prevent COVID-19 infection. Therefore, we designed the game MeetDurian, which integrates entertainment, sports, and education. For investigating factors influencing intention to play the MeetDurian, we proposed some comparative evaluation. Data were gathered from participants who participated in capturing virtual durians and completed questionnaires about immersion into the game, workload assessment, user's emotions, learning outcomes, and personal hygiene. These results proved the acceptability and usability of the mobile game-based MeetDurian for preventing the infection and severity of the COVID-19 pandemic.","Title: A MAPE-K Approach to Autonomic Microservices\nYear: 2022\n\nAbstract: Microservices are an emerging architectural style advocating for small loosely-coupled services in order to maximize scalability and adaptability. In order to help IT personnel, adaptability can be put (completely or partially) under the responsibility of the system using autonomic techniques, e.g., underpinned by a MAPE-K control loop. This paper discusses possible trade-offs, challenges and support techniques for soft-ware architects involved in building autonomic microservice-based systems.","Title: ROUTE: A Framework for Customizable Smart Mobility Planners\nYear: 2022\n\nAbstract: Multimodal journey planners are used worldwide to support travelers in planning and executing their journeys. Generated travel plans usually involve local mobility service providers, consider some travelers’ preferences, and provide travelers information about the routes’ current status and expected delays. However, those planners cannot fully consider the special situations of individual cities when providing travel planning services. Specifically, authorities of different cities might define customizable regulations or constraints of movements in the cities (e.g., due to construction works or pandemics). Moreover, with the transformation of traditional cities into smart cities, travel planners could leverage advanced monitoring features. Finally, most planners do not consider relevant information impacting travel plans, for instance, information that might be provided by travelers (e.g., a crowded square) or by mobility service providers (e.g., changing the timetable of a bus). To address the aforementioned shortcomings, in this paper, we propose ROUTE, a framework for customizable smart mobility planners that better serve the needs of travelers, local authorities, and mobility service providers in the dynamic ecosystem of smart cities. ROUTE is composed of an architecture, a process, and a prototype developed to validate the feasibility of the framework. Experiments’ results show that the framework scales well in both centralized and distributed deployment settings."],"string":"[\n \"Title: A car logistics scenario for context-aware adaptive service-based systems\\nYear: 2012\\n\\nAbstract: We present a logistic scenario, based on the sea port of Bremen, and a context-aware dynamic service-based system to support its operation. We also show how we have used it to evaluate our automated adaptation techniques.\",\n \"Title: A practical architecture-centric analysis process\\nYear: 2006\\n\\nAbstract: When engineering complex and distributed software and hardware systems (increasingly used in many sectors, such as manufacturing, aerospace, transportation, communication, energy and health-care), dependability has became a must, since failures can have economics consequences and can also endanger human life. Software Architectures (SA) can help improving the overall system dependability, providing a system blueprint that can be validated and that can guide all phases of the system development. Even if much work has been done on this direction, three important topics require major investigation: how different analysis techniques can be integrated together, how results obtained with SA-based analysis can be related to requirements and coding, and how to integrate new methodologies in the industrial software development life-cycle. In this paper we propose an architecture-centric analysis process which allows formal analysis driven by model-based architectural specifications. This analysis process satisfies the industrial requirements, since it is tool supported and based on semi-formal (UML-based) specifications.\",\n \"Title: A Variable Context Model for Adaptable Service-Based Applications\\nYear: 2012\\n\\nAbstract: Service-based applications SBAs rely on the invocation of services. The use of the service paradigm usually guarantees a high level of flexibility. In fact, applications can be easily reconfigured in order to continuously offer functionalities also in dynamic execution environments. This happens by changing the service selection and their composition. This flexibility can be exploited to design adaptable SBAs able to react to events that could happen during the application lifecycle. The execution flow of adaptable SBAs automatically changes on the basis of the context in which they are executing. The context includes information ranging from the situation in which users access the service-based applications to the status of the components involved in the execution of such applications. In this paper the authors propose a way to use context information to adapt SBAs. In particular, their goal is to discuss the way in which the context should be defined and managed in order to be exploited in the various activities related to the adaptation of service-based applications.\",\n \"Title: A context-driven adaptation process for service-based applications\\nYear: 2010\\n\\nAbstract: When building service-oriented systems the evolution of requirements and context is the norm rather than the exception. Therefore, it is important to make sure that the system is able to evolve as well without necessarily starting a completely new development process, and possibly on the fly. In this paper we specifically focus on the role of the context in the adaptation activities. For us context has various different facets as it includes information ranging from the situation in which users exploit a service-based application to the conditions under which the component services can be exploited. We elaborate on how and when the context should be defined, exploited, and evolved, and on the impact it has on the various activities related to adaptation of service-based applications. We use a case study to exemplify our first findings on this subject.\",\n \"Title: On-the-Fly Adaptation of Dynamic Service-Based Systems: Incrementality, Reduction and Reuse.\\nYear: 2013\\n\\nAbstract: On-the-fly adaptation is where adaptation activities are not explicitly represented at design time but are discovered and managed at run time considering all aspect of the execution environments. In this paper we present a comprehensive framework for the on-the-fly adaptation of highly dynamic service-based systems. The framework relies on advanced context-aware adaptation techniques that allow for i) incremental handling of complex adaptation problems by interleaving problem solving and solution execution, ii) reduction in the complexity of each adaptation problem by minimizing the search space according to the specific execution context, and iii) reuse of adaptation solutions by learning from past executions. We evaluate the applicability of the proposed approach on a real world scenario based on the operation of the Bremen sea port.\",\n \"Title: A Formalisation of Adaptable Pervasive Flows\\nYear: 2009\\n\\nAbstract: Adaptable Pervasive Flows is a novel workflow-based paradigm for the design and execution of pervasive applications, where dynamic workflows situated in the real world are able to modify their execution in order to adapt to changes in their environment. In this paper, we study a formalisation of such flows by means of a formal flow language. More precisely, we define APFoL (Adaptable Pervasive Flow Language) and formalise its textual notation by encoding it in Blite, a formalisation of WS-BPEL. The encoding in Blite equips the language with a formal semantics and enables the use of automated verification techniques. We illustrate the approach with an example of a Warehouse Case Study.\",\n \"Title: Model-Checking Plus Testing: From Software Architecture Analysis to Code Testing\\nYear: 2004\\n\\nAbstract: Software Model-Checking and Testing are some of the most used techniques to analyze software systems and identify hidden faults. While software model-checking allows for an exhaustive and automatic analysis of the system expressed through a model, software testing is based on a clever selection of \\\"relevant\\\" test cases, which may be manually or automatically run over the system. In this paper we analyze how those two analysis techniques may be integrated in a specific context, where a Software Architecture (SA) specification of the system is available, model-checking techniques axe used to validate the SA model conformance with respect to selected properties, while testing techniques are used to validate the implementation conformance to the SA model. The results of this research axe applied to an SDH Telecommunication system architecture designed by Siemens CNX.\",\n \"Title: Modelling Dynamic Software Architectures using Typed Graph Grammars\\nYear: 2008\\n\\nAbstract: Several recent research efforts have focused on the dynamic aspects of software architectures providing suitable models and techniques for handling the run-time modification of the structure of a system. A large number of heterogeneous proposals for addressing dynamic architectures at many different levels of abstraction have been provided, such as programmable, ad-hoc, self-healing and self-repairing among others. It is then important to have a clear picture of the relations among these proposals by formulating them into a uniform framework and contrasting the different verification aspects that can be reasonably addressed by each proposal. Our work is a contribution in this line. In particular, we map several notions of dynamicity into the same formal framework in order to distill the similarities and differences among them. As a result we explain different styles of architectural dynamisms in term of graph grammars and get some better insights on the kinds of formal properties that can be naturally associated to such different specification styles. We take a simple automotive scenario as a running example to illustrate main ideas.\",\n \"Title: Graph-Based Design and Analysis of Dynamic Software Architectures\\nYear: 2008\\n\\nAbstract: We illustrate two ways to address the specification, modelling and analysis of dynamic software architectures using: i) ordinary typed graph transformation techniques implemented in Alloy; ii) a process algebraic presentation of graph transformation implemented in Maude. The two approaches are compared by showing how different aspects can be tackled, including representation issues, modelling phases, property specification and analysis.\",\n \"Title: Web Service Composition Approaches: From Industrial Standards to Formal Methods\\nYear: 2007\\n\\nAbstract: Ensuring dependability and security of Peer-to- Peer (P2P) systems is an intricate task due to the autonomous and volatile nature of peers and the decentralization that characterizes such systems. Dynamic verification provides the means of monitoring ...\",\n \"Title: A Graph-based Design Framework for Global Computing Systems\\nYear: 2009\\n\\nAbstract: We present a framework for designing and analyzing Global Computing Systems using Dynamic Software Architectures. The framework, called TGG\\\"A, integrates typed graph grammars and the Alloy modeling language to specify Programmed Dynamic Software Architectures that represent systems that evolve their topology at runtime. We demonstrate the benefits of the framework by applying it to the study of an Automotive Software System.\",\n \"Title: Design for adaptation of service-based applications: main issues and requirements\\nYear: 2009\\n\\nAbstract: Service-based applications are considered a promising technology since they are able to offer complex and flexible functionalities in widely distributed environments by composing different types of services. These applications have to be adaptable to unforeseen changes in the functionality offered by component services and to their unavailability or decreasing performances. Furthermore, when applications are made available to a high number of potential users, they should also be able to dynamically adapt to the current context of use as well as to specific requirements and needs of the specific users. In order to address these issues, mechanisms that enable adaptation should be introduced in the life-cycle of applications, both in the design and in the runtime phases. In this paper we propose an extension of a basic iterative service-based applications lifecycle with elements able to deal with the adaptation-specific needs. We focus, in particular, on the design phase and suggest a number of design principles and guidelines that are suitable to enable adaptation. We discuss about the effectiveness of the proposed methodology by means of real-world scenarios over various types of service-based applications.\",\n \"Title: A framework for rule-based dynamic adaptation\\nYear: 2010\\n\\nAbstract: We propose a new approach to dynamic adaptation, based on the combination of adaptation hooks provided by the adaptable application specifying where adaptation can happen, and adaptation rules external to the application, specifying when and how adaptation can be performed. We discuss different design choices that have to be considered when using such an approach, and then we propose a possible solution. We describe the solution in details, we apply it to a sample scenario and we implement it on top of the language Jolie.\",\n \"Title: Towards an architectural approach for the dynamic and automatic composition of software components\\nYear: 2006\\n\\nAbstract: In a component-based software system the components are specified, designed and implemented with the intention to be reused, and are assembled in various contexts in order to produce a multitude of software systems. However, this ideal scenario is not always the case, e.g., the integration with legacy components. In this context, one main problem in component assembly arises. It is related to the ability to automatically and efficiently (i.e., by reducing the state-explosion phenomenon) synthesize an assembly code for a set of, possibly incompatible, software components. Moreover, this assembly should be able to evolve when things change and to be correct-by-construction, i.e., despite the changes, it always ensures a set of properties of interest. In this paper we propose a Software Architecture (SA) based approach in which architectural analysis and code synthesis are combined together in order to efficiently and correctly assemble a system out of a set of already implemented components. The approach can be equally applied to efficiently manage the whole re-factoring of the system when one or more components needs to be substituted, still maintaining the required properties. The specified and validated system SA is used as starting point for the derivation of adaptors required to correctly replace components in the composed system. The approach is applied and validated over an explanatory example concerning with a \\\"cooling water pipe\\\" system.\",\n \"Title: SOAdapt: A process reference model for developing adaptable service-based applications\\nYear: 2012\\n\\nAbstract: Context: The loose coupling of services and Service-Based Applications (SBAs) have made them the ideal platform for context-based run-time adaptation. There has been a lot of research into implementation techniques for adapting SBAs, without much effort focused on the software process required to guide the adaptation. Objective: This paper aims to bridge that gap by providing an empirically grounded software process model that can be used by software practitioners who want to build adaptable SBAs. The process model will focus only on the adaptation specific issues. Method: The process model presented in this paper is based on data collected through interviews with 10 practitioners occupying various roles within eight different companies. The data was analyzed using qualitative data analysis techniques. We used the output to develop a set of activities, tasks, stakeholders and artifacts that were used to construct the process model. Results: The outcome of the data analysis process was a process model identifying nine sets of adaptation process attributes. These can be used in conjunction with an organisation's existing development life-cycle or another reference life-cycle. Conclusion: The process model developed in this paper provides a solid reference for practitioners who are planning to develop adaptable SBAs. It has advantages over similar approaches in that it focuses on software process rather than the specific adaptation mechanism implementation techniques.\",\n \"Title: TESTOR: deriving test sequences from model-based specifications\\nYear: 2005\\n\\nAbstract: The dependability analysis of a component-based system may be driven by the components/system implementation or by the model-based specification provided prior to or together with the implementation. In particular, model-based specifications of a component-based system allows to explicitly model the structure and behavior of components and their integration, while model-based testing allows to derive test sequences which can be successively refined into test cases and then run onto the system implementation. Several techniques have been proposed so far to allow model-based testing. However, very few of them show certain characteristics which are peculiar for use in industrial contexts. We here describe TeStor, a TEst Sequence generaTOR algorithm which allows to extract test sequences from both state machine and scenario diagrams. We detail the algorithm, we apply it to a system study and we provide a link to its implementation.\",\n \"Title: An experience in using a tool for evaluating a large set of natural language requirements\\nYear: 2010\\n\\nAbstract: Requirements analysis is an important phase in a software project. It is often performed in an informal way by specialists who review documents looking for ambiguities, technical inconsistencies and incompleteness. Automatic evaluation of Natural Language (NL) requirements documents has been proposed as a means to improve the quality of the system under development. We show how the tool QuARS Express, introduced in a quality analysis process, is able to manage complex and structured requirement documents containing metadata, and to produce an analysis report rich of categorized information that points out linguistic defects and indications about the writing style of NL requirements. In this paper we report our experience using this tool in the automatic analysis of a large collection of natural language requirements, produced inside the MODCONTROL project.\",\n \"Title: An architectural approach to the correct and automatic assembly of evolving component-based systems\\nYear: 2008\\n\\nAbstract: Software components are specified, designed and implemented with the intention to be reused, and they are assembled in various contexts in order to produce a multitude of software systems. However, in the practice of software development, this ideal scenario is often unrealistic. This is mainly due to the lack of an automatic and efficient support to predict properties of the assembly code by only assuming a limited knowledge of the properties of single components. Moreover, to make effective the component-based vision, the assembly code should evolve when things change, i.e., the properties guaranteed by the assembly, before a change occurs, must hold also after the change. Glue code synthesis approaches technically permit one to construct an assembly of components that guarantees specific properties but, practically, they may suffer from the state-space explosion phenomenon. In this paper, we propose a Software Architecture (SA) based approach in which the usage of the system SA and of SA verification techniques allows the system assembler to design architectural components whose interaction is verified with respect to the specified properties. By exploiting this validation, the system assembler can perform code synthesis by only focusing on each single architectural component, hence refining it as an assembly of actual components which respect the architectural component observable behaviour. In this way code synthesis is performed locally on each architectural component, instead of globally on the whole system interactions, hence reducing the state-space explosion phenomenon. The approach can be equally well applied to efficiently manage the whole reconfiguration of the system when one or more components need to be updated, still maintaining the required properties. The specified and verified system SA is used as starting point for the derivation of glue adaptors that are required to apply changes in the composed system. The approach is firstly illustrated over an explanatory example and is then applied and validated over a real-world industrial case study.\",\n \"Title: QoS Composition of Services for Data-Intensive Application\\nYear: 2007\\n\\nAbstract: Ensuring dependability and security of Peer-to- Peer (P2P) systems is an intricate task due to the autonomous and volatile nature of peers and the decentralization that characterizes such systems. Dynamic verification provides the means of monitoring ...\",\n \"Title: Formal analysis and verification of self-healing systems\\nYear: 2010\\n\\nAbstract: Self-healing (SH-)systems are characterized by an automatic discovery of system failures, and techniques how to recover from these situations. In this paper, we show how to model SH-systems using algebraic graph transformation. These systems are modeled as typed graph grammars enriched with graph constraints. This allows not only for formal modeling of consistency and operational properties, but also for their analysis and verification using the tool AGG. We present sufficient static conditions for self-healing properties, deadlock-freeness and liveness of SH-systems. The overall approach is applied to a traffic light system case study, where the corresponding properties are verified.\",\n \"Title: Adaptation of service-based business processes by context-aware replanning\\nYear: 2011\\n\\nAbstract: Service-based business processes are typically used by organizations to achieve business goals through the coordinated execution of a set of activities implemented as services and service compositions. Since they are executed in dynamic, open and non-deterministic environments, business processes often need to be adapted to exogenous context changes and execution problems. In this paper we provide an adaptation approach that can automatically adapt business processes to run-time context changes that impede achievement of a business goal. We define a formal framework that adopts planning techniques to automatically derive necessary adaptation activities on demand. The adaptation consists in identifying recovery activities that guarantee that the execution of a business process can be successfully resumed and, as a consequence, the business goals are achieved. The solution proposed is evaluated on a real-world scenario from the logistics domain.\",\n \"Title: Automatic synthesis of coordinators for COTS group-ware applications: an example\\nYear: 2003\\n\\nAbstract: The coordination of concurrent activities in collaborativeenvironments is a very important and difficult task.Many approaches for the construction of large-scale flexiblegroup-ware applications there exist in the literature. Theyprovide valid support to modelling, analysis and to a white-boxdeveloping of coordination protocols for computer supportedcooperative applications. Little attention has beendedicated so far to group-ware applications built by assemblingthird-party components. In this paper by means ofan explanatory example, we apply a software architecturebased approach to the group-ware systems development.The software architecture imposed on the coordinating partof the system, allows for detection and recovery of possibleand unpredictable concurrent activities conflicts. Moreover,the approach allows the enforcing of coordination policieson the composed system by automatically synthesizing thepolicy-satisfying assembly code.\",\n \"Title: Dynamic Software Architecture Development: Towards an Automated Process\\nYear: 2009\\n\\nAbstract: We propose a software engineering process to aid the development of Dynamic Software Architectures (DSAs). This process is based on the sequential application of a number of formal methods and tools, and it can support software architects throughout the design, analysis and code generation of software systems. To illustrate the process, we apply it to an industrial case study from the Service Oriented Computing (SOC) domain.\",\n \"Title: ASTRO-CAptEvo: Dynamic Context-Aware Adaptation for Service-Based Systems\\nYear: 2012\\n\\nAbstract: Adaptivity is a key feature of service-based systems to fully exploit the advantages offered by the service paradigm. In this paper we present a comprehensive framework that can be used to define and support highly adaptable context-aware service-based business processes. In our approach, all the adaptation-related tasks, from detecting an adaptation problem to finding a solution and applying it to a running process instance, are performed automatically at run time. We also show how the framework has been implemented and applied to a real-world scenario from the logistics domain.\",\n \"Title: Domain Objects for Continuous Context-Aware Adaptation of Service-Based Systems\\nYear: 2013\\n\\nAbstract: The idea to build systems based on services, by reusing and combining software made available independently via different technologies and channels and dynamically organizing them into coherent processes, has a very well recognized potential. Achieving this potential stands crucially on the ability to recognize and exploit the context in which such applications operate, in terms of the available services, of the actual setup at run-time, and of the interaction with human actors. Changing contexts require run-time reaction, by adapting the ongoing overall process enacted by the service-based system to unexpected deviations. Continuous context-aware adaptation is hencefore a strong requirement in this setting. In this paper, we propose a service delivery platform designed for the continuous context-aware adaptation of service-based systems, based on the idea of monitoring the underlying context via a hierarchical model, and using the context to drive the choice and execution of adaptive pervasive flows. We describe the approach through an example from the smart cities e-mobility domain.\",\n \"Title: Dynamic Adaptation of Fragment-Based and Context-Aware Business Processes\\nYear: 2012\\n\\nAbstract: We propose a comprehensive framework for adaptivity of service-based applications, which exploits the concept of process fragments as a way to model reusable process knowledge and to allow for the dynamic, incremental, context- aware composition of such fragments into adaptable service-based applications. The framework provides a set of adaptation mechanisms that, combined through adaptation strategies, are able to solve complex adaptation problems. An implementation of the proposed solution is presented and evaluated on a real world scenario from the logistics domain.\",\n \"Title: CAptEvo: context-aware adaptation and evolution of business processes\\nYear: 2011\\n\\nAbstract: CAptEvo is a framework for the adaptation and evolution of service-based business processes operating in dynamic execution environments. In this demonstration, we apply the CAptEvo to a case study from the logistics domain and show its advantages in handling highly complex dynamic real-world business applications.\",\n \"Title: Architecting Fault-tolerant Component-based Systems: from requirements to testing\\nYear: 2007\\n\\nAbstract: Fault tolerance is one of the most important means to avoid service failure in the presence of faults, so to guarantee they will not interrupt the service delivery. Software testing, instead, is one of the major fault removal techniques, realized in order to detect and remove software faults during software development so that they will not be present in the final product. This paper shows how fault tolerance and testing can be used to validate component-based systems. Fault tolerance requirements guide the construction of a fault-tolerant architecture, which is successively validated with respect to requirements and submitted to testing. The theory is applied over a mining control system running example.\",\n \"Title: Using a Lifecycle Model for Developing and Executing Adaptable Interactive Distributed Applications\\nYear: 2010\\n\\nAbstract: We describe a case study on using the generic Lifecycle Model developed in the S-Cube project for a novel class of Real-time Online Interactive Applications (ROIA), which include distributed simulations (e.g. massively-multiplayer online games), e-learning and training. We describe how the Lifecycle Model supports application development by addressing the specific challenges of ROIA: a large number of concurrent users connected to a single application instance, frequent real-time user interactions, enforcement of Quality of Service (QoS) parameters, adaptivity to changing loads, and competition-oriented interaction between users, other actors, and services. We describe the implementation aspects of the application development and adaptation using the RTF (Real-Time Framework) middleware, and report experimental results for a sample online game application.\",\n \"Title: An architecture-centric approach for producing quality systems\\nYear: 2005\\n\\nAbstract: Software architecture has been advocated as an effective means to produce quality systems. In this paper, we argue that integration between analysis conducted at different stages of development is still lacking. Hence we propose an architecture-centric approach which, by combining different technologies and tools for analysis and testing, supports a seamless tool-supported approach to validate required properties. The idea is to start from the requirements, produce a validated model of the SA, and then use the SA to derive a set of conformance test cases. In this paper, we outline the process, and discuss how some existing tools, namely QuARS,ModTest, CowTest and UIT, could be exploited to support the approach. The integrated framework is under development.\",\n \"Title: From Requirements to code: an Architecture-centric Approach for producing Quality Systems\\nYear: 2009\\n\\nAbstract: When engineering complex and distributed software and hardware systems\\n(increasingly used in many sectors, such as manufacturing, aerospace,\\ntransportation, communication, energy, and health-care), quality has become a\\nbig issue, since failures can have economics consequences and can also endanger\\nhuman life. Model-based specifications of a component-based system permit to\\nexplicitly model the structure and behaviour of components and their\\nintegration. In particular Software Architectures (SA) has been advocated as an\\neffective means to produce quality systems. In this chapter by combining\\ndifferent technologies and tools for analysis and development, we propose an\\narchitecture-centric model-driven approach to validate required properties and\\nto generate the system code. Functional requirements are elicited and used for\\nidentifying expected properties the architecture shall express. The\\narchitectural compliance to the properties is formally demonstrated, and the\\nproduced architectural model is used to automatically generate the Java code.\\nSuitable transformations assure that the code is conforming to both structural\\nand behavioural SA constraints. This chapter describes the process and\\ndiscusses how some existing tools and languages can be exploited to support the\\napproach.\",\n \"Title: Dynamic Software Architectures Verification using DynAlloy\\nYear: 2008\\n\\nAbstract: Graph Grammars have been often used for modeling dynamic changes in software architectures. In particular, we have previously characterized some classes of dynamicity in terms of particular aspects of graph grammars. Moreover we have identified classes of properties that can be naturally associated to any of such kinds of dynamicities. In this paper we approach the problem of verifying such prop- erties over graph grammars specifications. In particular, we use DYNALLOY for attempting this task and we have concentrated on proving properties associated to a particular programmable dynamic software architecture.\",\n \"Title: Evaluation Of Natural Language Requirements In The Modcontrol Project\\nYear: 2008\\n\\nAbstract: We describe QuARS (Quality Analyzer for Requirement Specifications) Express, a customized version of the QuARS tool. It is designed to evaluate natural language requirements, can handle complex and structured data formats containing metadata, and is able to produce an analysis report with categorized information.\",\n \"Title: A Context-Aware Framework for Business Processes Evolution\\nYear: 2011\\n\\nAbstract: Run-time adaptability is a key feature of dynamic business environments, where the processes need to be constantly refined and restructured to deal with exceptional situations and changing requirements. The execution of such a system results in a set of adapted process variants instantiated on the same process model but dynamically restructured to handle specific contexts. Process evolution exploits the information on process variants to identify the best performing recurring adaptations and adopt them as general solutions in the process model. However, process variants are strictly related to specific execution contexts and cannot be adopted as general solutions. We propose a framework supporting context-aware evolution of business processes based on process instance execution and adaptation history. Instead of looking for recurring adaptations, we propose to look for recurring adaptation needs (i.e., process instances with the same context constraint violation and system configuration). Based on the analysis of adapted instances, we automatically construct and rank corrective evolution variants which can handle the problematic context. At the same time, we try to identify preventive evolution variants by constructing process variants which can prevent the adaptation need. We demonstrate the benefits of our approach using a car logistics scenario.\",\n \"Title: Towards Modeling and Execution of Collective Adaptive Systems.\\nYear: 2013\\n\\nAbstract: Collective Adaptive Systems comprise large numbers of heterogeneous entities that can join and leave the system at any time depending on their own objectives. In the scope of pervasive computing, both physical and virtual entities may exist, e. g., buses and their passengers using mobile devices, as well as citywide traffic coordination systems. In this paper we introduce a novel conceptual framework that enables Collective Adaptive Systems based on well-founded and widely accepted paradigms and technologies like service orientation, distributed systems, context-aware computing and adaptation of composite systems. Toward achieving this goal, we also present an architecture that underpins the envisioned framework, discuss the current state of our implementation effort, and we outline the open issues and challenges in the field.\",\n \"Title: Adaptivity in dynamic service-based systems\\nYear: 2012\\n\\nAbstract: Adaptivity for service-based systems is one of the most challenging research problems to fully exploit the dinamicity promised by the service paradigm. In this paper we present the research results achieved by the FBK SOA unit within the S-Cube Network, aiming at addressing key challenges in this area: context-aware adaptation, user-centric adaptation, cross- and multi-layer adaptation.\",\n \"Title: Domain Objects for Dynamic and Incremental Service Composition.\\nYear: 2014\\n\\nAbstract: A key feature of service-based applications (SBAs) is the capacity to dynamically define the composition of services independently available, which is required to achieve user goals. For this reason, to effectively deal with the obstacles due to continuous context changes, an incremental refinement of provided services is needed. We propose a new model that allows service functionalities to be defined partially, through the use of abstract activities. The refinement of these activities is postponed and performed incrementally at runtime, using the actual context as a guide. Our approach lets a service provider avoid the hard-coding of all service functionalities and their possible compositions at design time, delaying their refinement until the execution phase. Consequently the whole SBA's design becomes modular and flexible to better meet the typical dynamism of SBA. We illustrate the approach through an example scenario from the urban mobility domain.\",\n \"Title: Research challenges on multi-layer and mixed-initiative monitoring and adaptation for service-based systems\\nYear: 2012\\n\\nAbstract: Adaptation of complex service-based systems is one of the most challenging research problems for the Future Internet. A considerable effort has been dedicated in recent years to address this problem. However, there are still several important issues that call for concrete solutions. In this paper, we present a set of research challenges for muti-layer and mixed-initiative adaptation and monitoring that may guide the research in this area for the next 5-10 years.\",\n \"Title: A Goal Model for Collective Adaptive Systems\\nYear: 2014\\n\\nAbstract: A collective adaptive system is composed of large numbers of autonomous and self-adaptive entities which are able to provide benefits for other participants and have to cooperate with each other to accomplish their individual goals. When entities adapt their own behaviour due to unexpected situations, this may result in breaking the overall collaboration if these are not executed simultaneously and do not respect some collective constraints. The objective of this paper is to present a goal model that allows to express requirements for collective adaptability. It includes (i) how to specify the behaviour of the entities that encodes cooperation with other entities, (ii) how to link collaborative goals and individual goals, and (iii) how to specify constraints that are imposed on different entities to preserve some form of collective consistency while they are adapted.\",\n \"Title: Self-Repairing systems modeling and verification using AGG\\nYear: 2009\\n\\nAbstract: Self-repairing (or healing) systems are systems equipped with a mechanism that monitors the system behaviour to determine whether it behaves within prefixed parameters. If a deviation exists, then the system itself is in charge of adapting its configuration. In this paper we show how to model self-repairing systems by means of dynamic software architectures (DSAs). DSAs are formalized as typed (hyper) graph grammars (TGGs) and this formalization enables verification of correctness and completeness of self-repairing systems. DSAs are modeled and verified by using the attributed graph grammar system (AGG). The overall approach is applied to a traffic light system case study.\",\n \"Title: All Together Now: Collective Intelligence for Computer-Supported Collective Action\\nYear: 2015\\n\\nAbstract: In this position paper, we argue that a new methodological paradigm and software platform is required for developing citizen-oriented social computing applications. The platform that we propose is based on the idea of 'Collective Intelligence as a Service', and is grounded in the formalisation of computational models derived from an empirical analysis of psychological processes and social practices. This in turn provides the enablers for developing radically innovative tools for computational sustainability and computer-supported collective action in smart communities (e.g. Smart cities). Our vision is illustrated with two exemplars, one a healthcare application for patients with peripheral arterial disease, and the other an application for collaborative energy conservation to meet targets set out in a city's Sustainable Energy Action Plan.\",\n \"Title: An Approach for Collective Adaptation in Socio-Technical Systems\\nYear: 2015\\n\\nAbstract: Socio-technical systems are systems where autonomous humans and computational entities collectively collaborate with each other to satisfy their goals in a dynamic environment. To be resilient, such systems need to adapt to unexpected human behaviours and exogenous changes in the environment. In this paper, we describe a framework for the development of social-technical systems where adaptation is itself a collective process driven by the awareness of capabilities, goals, constraints and preferences of humans and entities, and knowledge of the environment. The adaptation is controlled by a multi-criteria decision making function combined with an analytic hierarchic process (AHP). We present our approach, the collective adaptation algorithm, and its application to a smart mobility scenario.\",\n \"Title: Sustainable Safety in Mobile Multi-robot Systems via Collective Adaptation\\nYear: 2015\\n\\nAbstract: To be safe, mobile multi-robots systems need to be able to adapt to unexpected behaviours of robots as well as to exogenous changes in the environment. In this paper, we describe a novel approach for the development of multi-robots systems where robots collectively collaborate with each other to satisfy their goals and to adapt their behaviour in a collective way satisfying the overall system safety. Safety-specific self-adaptation capabilities of the approach are generic and independent from the functional behaviour of the robots. An example dealing with safety for autonomous UAV is provided as well.\",\n \"Title: Design for Adaptation of Distributed Service-Based Systems.\\nYear: 2015\\n\\nAbstract: Internet of Services applications need to cope with a continuously changing environment, both in terms of the context in which they operate, and of the services, users and providers involved. In this setting, adaptivity is to be considered an intrinsic characteristic of applications rather than an exception to be handled. In this paper we propose a design for adaptation approach that fully exploits the advantages of the service-oriented paradigm to support the development and operation of service-based applications operating in highly dynamic environments. The approach is based on dynamic and incremental service composition and re-configuration techniques and is evaluated on a real-world scenario in the Smart Cities domain.\",\n \"Title: Distributed Service Co-evolution Based on Domain Objects.\\nYear: 2015\\n\\nAbstract: Service evolution is a critical ingredient of the service lifecycle. The more our society depends on large-scale, complex service environments including cloud and mobile services, the more pressing becomes the question of how to evolve a service on the fly at runtime, without bringing whole systems to a halt, due to unintended percolation of evolution effects through service inter-dependency chains. Thus, there is an urgent need for coordinated service evolution (co-evolution). This paper contributes a conceptual solution for dynamic, on-the-fly co-evolution of services, as well as a framework that supports the engineering of such co-evolution support. Our solution is built on top of the Domain Objects architectural concept and service-oriented computing model. We also analyze the types of changes that might happen in a service and their potential impact on dependent clients and servers, and discuss the benefits of our approach on those service co-evolution scenarios.\",\n \"Title: Preface to DAS 2016\\nYear: 2016\\n\\nAbstract: Presents the introductory welcome message from the conference proceedings. May include the conference officers' congratulations to all involved with the conference event and publication of the proceedings record.\",\n \"Title: Incremental Composition for Adaptive By-Design Service Based Systems\\nYear: 2016\\n\\nAbstract: A key challenge posed by the Internet of Services is that applications need to cope with a continuously changing environment, both in terms of the context in which they operate and of the services, users and providers involved. Differently from applications where traditional change detection and adaptation mechanisms can be used, the Internet of Services requires systems that are adaptive by design. In this paper we present a design for adaptation framework supporting the modeling, development and operation of service based applications operating in highly dynamic environments. The approach exploits advanced techniques for dynamic and incremental service composition, allowing to effectively deal with changes occurring at different levels in the system. An implementation of the proposed solution is presented and evaluated on a real-world scenario from the Smart Urban Mobility domain.\",\n \"Title: SMART: A process-oriented methodology for resilient smart cities.\\nYear: 2016\\n\\nAbstract: Cities are engines of economic prosperity and social development. Rapid urbanization and the impacts of climate change have resulted in increased vulnerabilities in cities. On the other hand, the increasing proliferation of connected devices and distributed monitoring of the environment around us has opened up an opportunity to transform the way we create and manage cities. Contextual evidence of performance, outcome and efficiency can now be readily collected at a higher resolution to aid multi-disciplinary and multi-objective decision-making, enabling optimal evolution of cities against the backdrop of constrained resources and intensified vulnerabilities. This paper first argues that distributed and ubiquitous monitoring is at the heart of smart cities. Insights can be inferred from the gathered data with potential for evidence-based decisions at the required spatial and temporal scales. The paper then discusses the development of a comprehensive but concise frameworks called DICES (data, insights, citizen, evidence and standards) for conceptualizing smart cities. The dimensions of DICES are then translated into a process oriented methodology called SMART (specify, monitor, analyze, resolve and transform) by formalizing key aspects of the smart city process. Generality and scalability of DICES and SMART are demonstrated through the development of REPRO, a risk- and evidence-based platform for resilient and optimal design of buildings and infrastructure in a smart city.\",\n \"Title: Leveraging Collective Run-Time Adaptation for UAV-Based Systems\\nYear: 2016\\n\\nAbstract: UAV-based systems are systems that are composed of a team of drones, various devices (like movable cameras, sensors), and human agents, which collaborate each other to accomplish defined missions. Since humans are constituent part of these systems, UAV-based systems are both mission-critical and safety-critical. Moreover, these systems are requested to operate in potentially unpredictable and unknown environments. A model of the environment describing, e.g. obstacles, no-fly zones, wind and weather conditions might be available, however, the assumption that such model is both correct and complete is often wrong. In this paper, we describe a novel approach for managing the run-time adaptation of UAV-based systems. Our approach is based on a generic collective adaptation engine that addresses collective adaptation problems in a decentralized fashion, operates at run-time, and enables the addition of new entities at any time. Moreover, our approach dynamically understands which parts of the system should be selected to solve an adaptation issue. The feasibility and scalability of the approach have been empirically evaluated in the context of a private company surveillance scenario.\",\n \"Title: A context-aware framework for dynamic composition of process fragments in the internet of services.\\nYear: 2017\\n\\nAbstract: In the last decade, many approaches to automated service composition have been proposed. However, most of them do not fully exploit the opportunities offered by the Internet of Services (IoS). In this article, we focus on the dynamicity of the execution environment, that is, any change occurring at run-time that might affect the system, such as changes in service availability, service behavior, or characteristics of the execution context. We indicate that any IoS-based application strongly requires a composition framework that supports for the automation of all the phases of the composition life cycle, from requirements derivation, to synthesis, deployment and execution. Our solution to this ambitious problem is an AI planning-based composition framework that features abstract composition requirements and context-awareness. In the proposed approach most human-dependent tasks can be accomplished at design time and the few human intervention required at run time do not affect the system execution. To demonstrate our approach in action and evaluate it, we exploit the ASTRO-CAptEvo framework, simulating the operation of a fully automated IoS-based car logistics scenario in the Bremerhaven harbor.\",\n \"Title: Combining Self-Organisation and Autonomic Computing in CASs with Aggregate-MAPE\\nYear: 2016\\n\\nAbstract: Aggregate computing is a recently proposed framework to build CASs (collective adaptive systems) by focussing on direct programming of ensembles so as to abstract away from individual devices and their single interaction acts: this approach is shown to streamline the identification of highly reusable block components, and support reasoning about their resiliency properties. Following this paradigm, in this paper we present a framework for bridging the gap between the MAPE (Monitor-Analyse-Plan-Execute) loop of autonomic computing managers, and fully-distributed self-organising CASs. This is achieved by seeing the collection of M components of each agent as an aggregate, amenable to a direct specification as overall CAS Monitoring behaviour, and similarly for A, P and E. As a result, a self-organising CAS can be programmed by clearly separating the M, A, P, and E parts of it, though each is expressed in terms of a collective behaviour. The proposed approach is exemplified with an application scenario of crowd dispersal in a large-scale smart-mobility application.\",\n \"Title: Towards learning domain-independent planning heuristics.\\nYear: 2017\\n\\nAbstract: Automated planning remains one of the most general paradigms in Artificial Intelligence, providing means of solving problems coming from a wide variety of domains. One of the key factors restricting the applicability of planning is its computational complexity resulting from exponentially large search spaces. Heuristic approaches are necessary to solve all but the simplest problems. In this work, we explore the possibility of obtaining domain-independent heuristic functions using machine learning. This is a part of a wider research program whose objective is to improve practical applicability of planning in systems for which the planning domains evolve at run time. The challenge is therefore the learning of (corrections of) domain-independent heuristics that can be reused across different planning domains.\",\n \"Title: DeMOCAS: Domain Objects for Service-Based Collective Adaptive Systems.\\nYear: 2016\\n\\nAbstract: DeMOCAS is a framework for the modeling and execution of service-based collective adaptive systems operating in dynamic environments. In this framework, we apply the Domain Object model and a Collective Adaptation algorithm to a case study from the mobility domain and we show its advantages in handling large-scale, decentralized and adaptive applications.\",\n \"Title: Decentralized Dynamic Adaptation for Service-Based Collective Adaptive Systems.\\nYear: 2016\\n\\nAbstract: Modern service-based systems are progressively becoming more heterogeneous. They form a socio-technical system, composed of distributed entities, software and human participants, interacting with and within the environment. These systems operate under constant perturbations that are due to unexpected changes in the environment and to the unpredictable behavior of the participants. We argue that for a service-based system to be resilient, adaptation must be collective. Multiple participants must adapt their behavior in concert to respond to critical runtime impediments. In this work, we present a framework for the modeling and execution of large-scale service-based Collective Adaptive Systems, where adaptation needs are solved in a decentralized and collective manner.\",\n \"Title: Towards a Domain Specific Language for Engineering Collective Adaptive Systems\\nYear: 2017\\n\\nAbstract: Heterogeneous agents that cooperate to accomplish collective tasks constitute Collective Adaptive Systems (CAS). Engineering a CAS not only involves the definition of the individual agents, but also their roles in achieving a collective task and adaptation strategies to counteract to environmental changes. Current solutions for specifying CAS typically tackle the problem at a low level of abstraction (e.g., writing XML files), making this task time-consuming and error-prone. Moreover, such a low level of abstraction hinders the understandability of the specification. Model-Driven Engineering (MDE) proposes to reduce the complexity of development by adopting models as first class artifacts in the process. In this respect, this work proposes a MDE approach to enhance CAS specification. In particular, we introduce a domain-specific language (DSL) made-up of three main views: one devoted to adaptive systems design; one addressing ensembles definition; and one tackling the collective adaptation. These three separate aspects are woven seamlessly by the DSL to constitute a complete CAS design. While the different views allow us to exploit separation-of-concerns to reduce complexity and focus on a specific aspect of the system, facing CAS specification at a higher-level of abstraction permits to use concepts closer to the experts of the involved domains. Moreover, the precise definition of modeling concepts through corresponding meta-models enables correctness-by-construction of the system specification.\",\n \"Title: CAStlE: A Tool for Collective Adaptive Systems Engineering\\nYear: 2017\\n\\nAbstract: In this paper we propose CAStlE, a MDE approach to enhance Collective Adaptive System (CAS) specification. In particular, we introduce a domain-specific language (DSL) made-up of three main views: one devoted to adaptive systems design; one addressing ensembles definition; and one tackling the collective adaptation. These three separate aspects are woven seamlessly by the DSL to constitute a complete CAS design. Moreover, each of the defined views conveys the creation of a corresponding model editor, which allows for the three aspects of a CAS to be independently designed by CAStlE.\",\n \"Title: Domain Objects and Microservices for Systems Development: a roadmap.\\nYear: 2016\\n\\nAbstract: This paper discusses a roadmap to investigate Domain Objects being an adequate formalism to capture the peculiarity of microservice architecture, and to support Software development since the early stages. It provides a survey of both Microservices and Domain Objects, and it discusses plans and reflections on how to investigate whether a modeling approach suited to adaptable service- based components can also be applied with success to the microservice scenario.\",\n \"Title: From Monolithic to Microservices: An Experience Report from the Banking Domain.\\nYear: 2018\\n\\nAbstract: Microservices have seen their popularity blossoming with an explosion of concrete applications in real-life software. Several companies are currently involved in a major refactoring of their back-end systems in order to improve scalability. This article presents an experience report of a real-world case study, from the banking domain, in order to demonstrate how scalability is positively affected ...\",\n \"Title: Collective Adaptation Through Concurrent Planning: The Case Of Sustainable Urban Mobility\\nYear: 2018\\n\\nAbstract: In this paper we address the challenges that impede collective adaptation in smart mobility systems by proposing a notion of ensembles. Ensembles enable systems with collective adaptability to be built as emergent aggregations of autonomous and self-adaptive agents. Adaptation in these systems is triggered by a run-time occurrence, which is known as an issue. The novel aspect of our approach is, it allows agents affected by an issue in the context of a smart mobility scenario to adapt collaboratively with minimal impact on their own preferences through an issue resolution process based on concurrent planning algorithms.\",\n \"Title: Carpool: Collective Adaptation Using Concurrent Planning\\nYear: 2018\\n\\nAbstract: In this paper we present the CARPooL demonstrator, an implementation of a Collective Adaptation Engine (CAE) that addresses the challenge of collective adaptation in the smart mobility domain. CARPooL resolves adaptation issues via concurrent planning techniques. It also allows to interact with the provided solutions by adding new issues or analyzing the actions done by each agent.\",\n \"Title: Enacting Emergent Configurations in the IoT Through Domain Objects.\\nYear: 2018\\n\\nAbstract: The Internet of Things (IoT) pervades more and more aspects of our lives and often involves many types of smart connected objects and devices. User’s IoT environment changes dynamically, e.g., due to the mobility of the user and devices. Users can fully benefit from the IoT only when they can effortlessly interact with it. To accomplish this in a dynamic and heterogenous environment, we make use of Emergent Configurations (ECs), which consist of a set of things that connect and cooperate temporarily through their functionalities, applications, and services, to achieve a user goal. In this paper, we: (i) present the IoT-FED architectural approach to enable the automated formation and enactment of ECs. IoT-FED exploits heterogeneous and independently developed things, IoT services, and applications which are modeled as Domain Objects (DOs), a service-based formalism. Additionally, we (ii) discuss the prototype we developed and the experiments run in our IoT lab, for validation purposes.\",\n \"Title: Using a lifecycle model for developing and executing real-time online applications on clouds\\nYear: 2011\\n\\nAbstract: We describe how the generic Lifecycle Model developed in the S-Cube project for the design and management of service-based applications (SBA) can be utilized in the context of Cloud Computing. In particular, we focus on the fact that the Infrastructure-as-a-Service approach enables the development of Real-Time Online Interactive Applications (ROIA), which include multi-player online computer games, interactive e-learning and training applications and high-performance simulations in virtual environments. We illustrate how the Lifecycle Model expresses the major design and execution aspects of ROIA on Clouds by addressing the specific characteristics of ROIA: a large number of concurrent users connected to a single application instance, enforcement of Quality of Service (QoS) parameters, adaptivity to changing loads, and frequent real-time interactions between users and services. We describe how our novel resource management system RTF-RMS implements concrete mechanisms that support the developer in designing adaptable ROIA on Clouds according to the different phases of the Lifecycle Model. Our experimental results demonstrate the influence of the proposed adaptation mechanisms on the application performance.\",\n \"Title: ATLAS: A World-Wide Travel Assistant Exploiting Service-Based Adaptive Technologies.\\nYear: 2017\\n\\nAbstract: Nowadays, users can count on a large amount of mobility services offering disparate functionalities and providing all needed information. Yet, from a user perspective, properly exploiting the available mobility services to organize journeys meeting personal expectations, is becoming a complex task. Indeed, discover and select the appropriate services in an open and constantly expanding domain, is a challenging and time-consuming task. We claim that a uniform and easy way for exploiting these services while moving around, getting accurate and personalized information is still missing. In this paper we propose a platform for the definition of value-added mobility services by (i) enhancing interoperability among the existing services, (ii) supporting their execution via run-time adaptation, (iii) through the definition of multi-channel front-end applications. On top of the platform, we have implemented and evaluated a world-wide travel assistant.\",\n \"Title: Cyber-Storms Come from Clouds: Security of Cloud Computing in the IoT Era.\\nYear: 2019\\n\\nAbstract: The Internet of Things (IoT) is rapidly changing our society to a world where every thing is connected to the Internet, making computing pervasive like never before. This tsunami of connectivity and data collection relies more and more on the Cloud, where data analytics and intelligence actually reside. Cloud computing has indeed revolutionized the way computational resources and services can be used and accessed, implementing the concept of utility computing whose advantages are undeniable for every business. However, despite the benefits in terms of flexibility, economic savings, and support of new services, its widespread adoption is hindered by the security issues arising with its usage. From a security perspective, the technological revolution introduced by IoT and Cloud computing can represent a disaster, as each object might become inherently remotely hackable and, as a consequence, controllable by malicious actors. While the literature mostly focuses on the security of IoT and Cloud computing as separate entities, in this article we provide an up-to-date and well-structured survey of the security issues of cloud computing in the IoT era. We give a clear picture of where security issues occur and what their potential impact is. As a result, we claim that it is not enough to secure IoT devices, as cyber-storms come from Clouds.\",\n \"Title: The Resilience of \\\"Planes, Trains, and Automobiles\\\": Comment on \\\"Driverless Cars Will Make Passenger Rail Obsolete, \\\" by Yair Wiseman [Opinion].\\nYear: 2019\\n\\nAbstract: Reports on transportation systems in smart cities. Modern cities are complex socio-technical entities that exist to provide services effectively to their residents and visitors. In the mobility context, people need to travel quickly and conveniently between locations at different scales, ranging from a trip of a few blocks to a journey across town or further. Each trip has its set of requirements....\",\n \"Title: Microservices: Migration of a Mission Critical System\\nYear: 2021\\n\\nAbstract: An increasing interest is growing around the idea of microservices and the promise of improving scalability when compared to monolithic systems. Several companies are evaluating pros and cons of a complex migration. In particular, financial institutions are positioned in a difficult situation due to the economic climate and the appearance of agile competitors that can navigate in a more flexible l...\",\n \"Title: Preface of the 15th International Workshop on Models@run.time’21\\nYear: 2021\\n\\nAbstract: After a break in 2020, this year the 15th edition of the workshop Models@run.time is held at the 24th International Conference on Model Driven Engineering Languages and Systems. The workshop takes place virtually due to the Covid-19 pandemic on the 11th of October 2021. The workshop is organized by Sebastian Götz, Antonio Bucchiarone and Nelly Bencomo. Here, we present some highlights of the works...\",\n \"Title: POLYGLOT for Gamified Education: Mixing Modelling and Programming Exercises\\nYear: 2021\\n\\nAbstract: Gamification refers to the employment of gaming mechanisms for non-gaming purposes. Its aim is promoting the engagement of target users in pursuing certain goals, e.g. completing education paths. In this paper we present POLYGLOT, a gamified notebook-like programming environment. The gamification extension was built to target programming languages education, and in this work we illustrate how the ...\",\n \"Title: How to merge gamification efforts for programming and modelling: a tool implementation perspective\\nYear: 2021\\n\\nAbstract: Gamification, that is the use of gaming elements into non-game contexts, has gained a lot of interests in all those settings where the engagement of target users needs to be stimulated. Education and training have been historically struggling with keeping \\\"students\\\" motivated to pursue the completion of their learning paths. Lately these issues have been exacerbated by distance education: on the one hand, virtual participation to courses makes education far more accessible than requiring students to seat in the same classroom (and at the same time); on the other hand, the missing \\\"community building\\\" conveyed by physically attending the same course remarkably reduces students' engagement. In this respect, gamification has been applied as an engagement tool, e.g. in programming courses, by introducing challenges, awards, leader boards, and so forth, with the aim of motivating the students in keeping their efforts for completing their studies. In this paper we describe and compare our experiences in gamification solutions for programming and modelling. In particular, we distinguish some desirable features to have in gamification solutions for modelling courses, and illustrate our experiences in realizing them concretely. Our observations testify that while in principle many of the gamification elements coming from programming courses could be suitable also to engage students in modelling, there exist still remarkable obstacles in realizing them in practice.\",\n \"Title: Towards a Framework to Assist Iterative and Adaptive Design in Gameful Systems\\nYear: 2021\\n\\nAbstract: Over the years, gamification gained consensus among researchers and practitioners as a tool to motivate people to perform activities deemed as tedious or unexciting. Hence, there exist many and heterogeneous application domains that may benefit from gamification. However, the domain expert and the designer are often separate individuals with dissimilar backgrounds, skills, and understanding. Thus,...\",\n \"Title: MeetDurian: Can Location-Based Games be Used to Improve COVID-19 Hygiene Habits?\\nYear: 2022\\n\\nAbstract: The COVID-19 problem has not gone away with the passing of the seasons. Although most countries have achieved remarkable results in fighting against epidemic diseases and controlling viruses, the general public is still far from understanding the new crown virus and lack imagination on its transmission law. Location-based games (LBGs) have been challenged during the on-going pandemic. No research has shown that LBGs can be used to help prevent COVID-19 infection. Therefore, we designed the game MeetDurian, which integrates entertainment, sports, and education. For investigating factors influencing intention to play the MeetDurian, we proposed some comparative evaluation. Data were gathered from participants who participated in capturing virtual durians and completed questionnaires about immersion into the game, workload assessment, user's emotions, learning outcomes, and personal hygiene. These results proved the acceptability and usability of the mobile game-based MeetDurian for preventing the infection and severity of the COVID-19 pandemic.\",\n \"Title: A MAPE-K Approach to Autonomic Microservices\\nYear: 2022\\n\\nAbstract: Microservices are an emerging architectural style advocating for small loosely-coupled services in order to maximize scalability and adaptability. In order to help IT personnel, adaptability can be put (completely or partially) under the responsibility of the system using autonomic techniques, e.g., underpinned by a MAPE-K control loop. This paper discusses possible trade-offs, challenges and support techniques for soft-ware architects involved in building autonomic microservice-based systems.\",\n \"Title: ROUTE: A Framework for Customizable Smart Mobility Planners\\nYear: 2022\\n\\nAbstract: Multimodal journey planners are used worldwide to support travelers in planning and executing their journeys. Generated travel plans usually involve local mobility service providers, consider some travelers’ preferences, and provide travelers information about the routes’ current status and expected delays. However, those planners cannot fully consider the special situations of individual cities when providing travel planning services. Specifically, authorities of different cities might define customizable regulations or constraints of movements in the cities (e.g., due to construction works or pandemics). Moreover, with the transformation of traditional cities into smart cities, travel planners could leverage advanced monitoring features. Finally, most planners do not consider relevant information impacting travel plans, for instance, information that might be provided by travelers (e.g., a crowded square) or by mobility service providers (e.g., changing the timetable of a bus). To address the aforementioned shortcomings, in this paper, we propose ROUTE, a framework for customizable smart mobility planners that better serve the needs of travelers, local authorities, and mobility service providers in the dynamic ecosystem of smart cities. ROUTE is composed of an architecture, a process, and a prototype developed to validate the feasibility of the framework. Experiments’ results show that the framework scales well in both centralized and distributed deployment settings.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":73,"string":"73"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":245,"string":"245"}}},{"rowIdx":246,"cells":{"question_id":{"kind":"string","value":"Chung Wei Lin"},"question":{"kind":"string","value":"Generate an abstract for the title \"Current path analysis for electrostatic discharge protection\" using the following items: ESD, IC pads, protection circuit, current paths, algorithm."},"answer":{"kind":"string","value":"The electrostatic discharge (ESD) problem has become a challenging reliability issue in nanometer circuit design. High voltages resulted from ESD might cause high current densities in a small device and burn it out, so on-chip protection circuits for IC pads are required. To reduce the design cost, the protection circuit should be added only for the IC pads with an ESD current path, which arises the ESD current path analysis problem. In this paper, we first introduce the analysis problem for ESD protection in circuit design. We then model the circuit as a constrained graph, decompose ESD connected components linked with the pads, and apply the breadth-first search (BFS) to identify the ESD connected components in each constrained graph and thus the current paths. Experimental results show that our algorithm can detect all ESD paths very efficiently and economically. To our best knowledge, our algorithm is the first point tool available to the public for the ESD analysis."},"correct_answer":{"kind":"string","value":"The electrostatic discharge (ESD) problem has become a challenging reliability issue in nanometer circuit design. High voltages resulted from ESD might cause high current densities in a small device and burn it out, so on-chip protection circuits for IC pads are required. To reduce the design cost, the protection circuit should be added only for the IC pads with an ESD current path, which arises the ESD current path analysis problem. In this paper, we first introduce the analysis problem for ESD protection in circuit design. We then model the circuit as a constrained graph, decompose ESD connected components linked with the pads, and apply the breadth-first search (BFS) to identify the ESD connected components in each constrained graph and thus the current paths. Experimental results show that our algorithm can detect all ESD paths very efficiently and economically. To our best knowledge, our algorithm is the first point tool available to the public for the ESD analysis."},"documents":{"kind":"list like","value":["Title: Calculate Golf Swing Trajectories from IMU Sensing Data\nYear: 2012\n\nAbstract: In the process of sport learning, learners spend a lot of time on practicing in order to develop correct action habit. Take golf practice as an example. Without the supervising of coaches, novices may keep practicing wrong swing actions, and that will cost more time later on to correct the wrong habit. It would be helpful to let learners can be aware of incorrect swing actions in self-training. In this work, we propose an IMU-based solution to help learners by allowing them to review their swing trajectories and also learn key features of the swings. In the proposed system, an IMU composed of an accelerometer, a magnetometer and a gyroscope is installed on the golf club to collect inertial motion data. From the collected data, swing trajectories can be calculated and swing features can also be extracted.","Title: Location Management of Correlated Mobile Users in the UMTS\nYear: 2005\n\nAbstract: In this paper, we propose concurrently searching for correlated mobile users in mobile communications networks. Previous work either focuses on locating a single mobile user or assumes that the locations of mobile users are statistically independent. We first propose a mobility model in which the movements of mobile users are statistically correlated. Next, we use the theory of Markov chain to derive the joint probability density function of the locations of mobile users. In addition, we propose a novel approach to discover the correlations among the locations of mobile users without explicitly calculating the joint probability density function. Our simulation results indicate that exploring the correlations among the locations of mobile users could significantly reduce the average paging delay and increase the maximum stable throughput.","Title: Cyber-Security for the Controller Area Network (CAN) Communication Protocol\nYear: 2012\n\nAbstract: We propose a security mechanism to help prevent cyber-attacks (masquerade and replay) in vehicles with architecture based on Controller Area Network (CAN). We focus on CAN as it will likely continue being used in upcoming in-vehicle architectures. The CAN protocol contains no direct support for secure communications. Retrofitting the protocol with security mechanisms poses several challenges given the very limited data rates available (e.g., 500kbps) since bus utilization may significantly increase. In this paper, we focus on a security mechanism which keeps the bus utilization as low as possible. Through our experimental results, we show that our security mechanism can achieve high security levels while keeping communication overheads (e.g., bus load and message latency) at reasonable levels.","Title: Obstacle-Avoiding Rectilinear Steiner Tree Construction Based on Spanning Graphs\nYear: 2008\n\nAbstract: Given a set of pins and a set of obstacles on a plane, an obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) connects these pins, possibly through some additional points (called the Steiner points), and avoids running through any obstacle to construct a tree with a minimal total wirelength. The OARSMT problem becomes more important than ever for modern nanometer IC designs which need to consider numerous routing obstacles incurred from power networks, prerouted nets, IP blocks, feature patterns for manufacturability improvement, antenna jumpers for reliability enhancement, etc. Consequently, the OARSMT problem has received dramatically increasing attention recently. Nevertheless, considering obstacles significantly increases the problem complexity, and thus, most previous works suffer from either poor quality or expensive running time. Based on the obstacle-avoiding spanning graph, this paper presents an efficient algorithm with some theoretical optimality guarantees for the OARSMT construction. Unlike previous heuristics, our algorithm guarantees to find an optimal OARSMT for any two-pin net and many higher pin nets. Extensive experiments show that our algorithm results in significantly shorter wirelengths than all state-of-the-art works.","Title: Timing analysis of process graphs with finite communication buffers\nYear: 2013\n\nAbstract: Real-Time Calculus (RTC) is a modular performance analysis framework for real-time embedded systems. It can be used to compute the worst-case and best-case response times of tasks with general activation patterns and configurations, such as pipelines of tasks that are connected via finite buffers. In this paper, we extend the existing RTC framework to analyze arbitrary graph configurations of tasks and messages, with mixed periodic and event-based activation models and finite buffers between any pair of nodes. Our extension also improves upon several sources of pessimism in the existing analysis. We present an application of the extended RTC to the Loosely Time-Triggered Architecture (LTTA) implementation of synchronous models, commonly used in the development of embedded automotive, avionics and control systems. We show how our method can be used to model scheduling and communication delays in an LTTA mapping, which gives tighter analysis bounds on the output rate and the latency compared to existing techniques. The evaluation on automotive workloads shows that our approach is scalable and outperforms existing techniques in terms of analysis accuracy.","Title: Efficient multi-layer obstacle-avoiding rectilinear Steiner tree construction\nYear: 2007\n\nAbstract: Given a set of pins and a set of obstacles on routing layers, a multi-layer obstacle-avoiding rectilinear Steiner minimal tree (ML-OARSMT) connects these pins by rectilinear edges within layers and vias between layers, and avoids running through any obstacle to construct a Steiner tree with a minimal total cost. The ML-OARSMT problem is very important for many VLSI designs with pins being located in multiple routing layers that contain numerous routing obstacles incurred from IP blocks, power networks, prerouted nets, etc. Therefore, it is desired to develop an effective algorithm for the ML-OARSMT problem. However, there is no existing work on the MLOARSMT problem. In this paper, we first formulate the MLOARSMT problem and identify key different properties of the problem from its single-layer counterpart. Based on the multi-layer obstacle-avoiding spanning graph (ML-OASG), we present the first algorithm to solve the ML-OARSMT problem. Our algorithm can guarantee an optimal solution for any 2-pin net and many higher-pin nets. Experiments show that our algorithm results in 33% smaller total costs on average than a construction-by-correction heuristic which is widely used for Steiner-tree construction in the recent literature.","Title: Recent Research and Emerging Challenges in Physical Design for Manufacturability/Reliability\nYear: 2007\n\nAbstract: As IC process geometries scale down to the nanometer territory, the industry faces severe challenges of manufacturing limitations. To guarantee yield and reliability, physical design for manufacturability and reliability has played a pivotal role in resolution and thus yield enhancement for the imperfect manufacturing process. In this paper, we introduce major challenges arising from nanometer process technology, survey key existing techniques for handling the challenges, and provide some future research directions in physical design for manufacturability and reliability.","Title: AR-Based Positioning for Mobile Devices\nYear: 2011\n\nAbstract: Augmented Reality (AR) that can be considered as a form of location-based services is a technique utilizing position and orientation information and a location database of POIs to enrich video or photographs by adding on graphics or text objects. The AR technique can be used to develop Pedestrian Navigation Systems (PNSs), but high-precision positioning is needed for displaying AR objects at proper places. However, the required level of accuracy is far beyond current commercial positioning solutions, e.g., outdoor GPS and indoor RF systems. In this paper, we propose an AR-based positioning technique for AR users to position their locations. First, by utilizing a coarse positioning system, AR objects can be roughly displayed on the touch screen of a AR device. Then, AR objects can be matched with their images on the display via drag-and-drop operations by users. Thus, both the coordinates of the AR objects in the image and in the real world can be known. Based on the coordinates along with the knowledge of the camera focal length, the location at which the photograph was taken can be known. The location of the camera can be treated as the location of the user. The proposed positioning technique is very helpful in developing high-precision PNSs.","Title: A multilayered audiovisual streaming system using the network bandwidth adaptation and the two-phase synchronization\nYear: 2009\n\nAbstract: Synchronous audiovisual streaming and playout are two of the major issues in the multimedia communication network. However, the past corresponding researches of media synchronization mainly focused on the mono-quality and single-layer (nonscalable) audiovisual data. To overcome challenges of ubiquitous multimedia streaming, a scalable audiovisual coder that can provide flexible scalabilities and adaptive streaming control to adapt to complicated network situations are both required. This paper proposes a multilayered audiovisual streaming scheme to deliver layered audiovisual data synchronously, which is called ML-AVSS. Fine-granular scalability (FGS) and bit-sliced arithmetic coding (BSAC) techniques are used to segment video and audio data into one base-layer and multiple enhancement-layer bitstreams. With advantages of audiovisual layer coding, a de-jitter procedure, a conditional retransmission mechanism and a playout synchronization mechanism are designed to transmit hybrid multilayered audiovisual bitstreams in consideration of the result of a network bandwidth adaptation and the distinct decoding time-complexity. Experimental results show that the proposed ML-AVSS is a feasible streaming scheme to overcome challenges of ubiquitous multimedia streaming, e.g., constrained channel bandwidth, quality degradation, unsmooth playout, etc.","Title: An Efficient Pre-Assignment Routing Algorithm for Flip-Chip Designs\nYear: 2012\n\nAbstract: The flip-chip package is introduced for modern integrated circuit (IC) designs with higher integration density and larger I/O counts. In this paper, we consider the pre-assignment flip-chip routing problem with predefined connections between driver pads and bump pads. This problem has been shown to be much more difficult than the free-assignment one, but is more popular in real-world designs because the connections between driver pads and bump pads are typically predetermined by IC or packaging designers. Based on the concept of routing sequence exchange, we propose a very efficient approach to guide the global routing by computing the longest common subsequence and the maximum planar subset of chords for pre-assignment flip-chips. We observe that the existing work over-constrains the capacity of a routing tile, which might miss some critical solution space with a better routing solution (e.g., smaller wirelength), and provide a remedy for this insufficiency to identify a better solution in a more complete solution space. We also develop a constant-time routability analyzer to check if a given set of wires can pass through a tile. Experimental results show that our router can achieve a $125\\times$ speedup with even better solution quality (same routability with slightly smaller wirelength), compared with a state-of-the-art flip-chip router based on integer linear programming.","Title: A multi-core based parallel streaming mechanism for concurrent video-on-demand applications\nYear: 2009\n\nAbstract: In this paper, we design a novel Multi-Core based Parallel Streaming Mechanism for concurrently streaming the scalable extension of H.264/AVC videos, which is called MCPSM. MC-PSM is able to serve lots of heterogeneous users who may utilize distinct terminals through distinct network interfaces to get on-demand videos from an ISP streaming server at meanwhile. With the concept of CPU scheduling- SJF (Shortest- Job-First) and multi-core based parallel programming, multiple streaming tasks can be executed in parallel using a proposed task dispatcher based on network connection speeds, video bit-rate and users' waiting time. Comparing with a normal-threading streaming approach, the average execution time can decrease effectively and CPU resources can be utilized more fully.","Title: Multilayer Obstacle-Avoiding Rectilinear Steiner Tree Construction Based on Spanning Graphs\nYear: 2008\n\nAbstract: Given a set of pins and a set of obstacles on routing layers, a multilayer obstacle-avoiding rectilinear Steiner minimal tree (ML-OARSMT) connects these pins by rectilinear edges within layers and vias between layers and avoids running through any obstacle to construct a Steiner tree with a minimal total cost. The ML-OARSMT problem is very important for many very large scale integration designs with pins being located in multiple routing layers that contain numerous routing obstacles incurred from IP blocks, power networks, prerouted nets, etc. As a fundamental problem with extensive practical applications to routing and wirelength/congestion/timing estimations in early design stages, it is desired to develop an effective algorithm for the ML-OARSMT problem to facilitate the design flow. However, there is no existing work on this ML-OARSMT problem. In this paper, we first formulate the ML-OARSMT problem with rectangular obstacles and then identify key different properties of this problem from its single-layer counterpart. Based on the multilayer obstacle-avoiding spanning graph, we present the first algorithm to solve the ML-OARSMT problem. Our algorithm can guarantee an optimal solution for any two-pin net and many multiple-pin nets. Experiments show that our algorithm results in 33% smaller total costs on average than a construction-by-correction heuristic which is widely used for Steiner-tree construction in the recent literature.","Title: Mobility Management for Video Streaming on Heterogeneous Networks\nYear: 2010\n\nAbstract: This article discusses how ubiquitous video streaming platform can let people enjoy continuous multimedia services at any time, in any location, and with any computing device. There are several technical challenges to be met in the process of achieving this goal. These challenges entail developing sophisticated session handoff control, session descriptions, communication signaling, and adaptive video streaming, among other factors.","Title: An Efficient Wire Routing and Wire Sizing Algorithm for Weight Minimization of Automotive Systems\nYear: 2014\n\nAbstract: As the complexities of automotive systems increase, designing a system is a difficult task that cannot be done manually. In this paper, we propose an algorithm for weight minimization of wires used for connecting electronic devices in a system. The wire routing problem is formulated as a Steiner tree problem with capacity constraints, and the location of a Steiner vertex is selected for adding a splice connecting more than two wires. Besides wire routing, wire sizing is also done to satisfy resistance constraints and minimize the total wiring weight. Experimental results show the effectiveness and efficiency of our algorithm.","Title: A Hybrid Spatial-Temporal Fine Granular Scalable Coding for Adaptive QoS Internet Video\nYear: 2005\n\nAbstract: In a ubiquitous multimedia space, a video streaming service is requested to be continuous and uninterrupted even if a client may change her/his client device, network link and preferences at any time and anywhere. Thus, a video coder that can provide more wide range quality-of-service (QoS) and more flexible control is urgently required. This paper presents a hybrid coder structure that integrates spatial-, temporal- and SNR-scalabilities to handle MPEG-4 videos. Using the proposed hybrid coder, different presentation qualities, including spatial-temporal resolution and SNR quality, can be rendered when frames are decoded from the base-layer (BL) and partial enhancement-layer (EL) subbitstreams. Besides, a refined rate-adaptation approach in the MPEG-4 FGS scheme and a buffer control mechanism are also devised to increase the bandwidth utilization and to prevent buffer instability. According to the experiments results, the proposed hybrid coder shows outperformances over classic non-scalable MPEG-2 and MPEG-4 FGS coder in consideration of the flexible QoS for Internet video streaming.","Title: A Predictive Video-on-Demand Bandwidth Management Using the Kalman Filter over Heterogeneous Networks\nYear: 2009\n\nAbstract: In order to adapt the quality of an on-demand video stream over a time-varying bandwidth channel, a network-aware bandwidth estimation and rate control scheme are required. This paper proposes a predictive video-on-demand (VoD) bandwidth management and a feedback-based buffer control scheme for streaming fine granular scalability videos over wired/WLAN/3G networks. The predictive VoD bandwidth management includes two parts: bandwidth estimation and rate adaptation. According to the measured information of packet round-trip-time, loss-rate, delay jitter and received bit-rate, an improved Kalman filter is proposed to predict an available bandwidth recursively, and to determine a proper transmission rate in consideration of buffer fullness of a decoder. The optimal parameters of the Kalman filter, e.g. a transition matrix and error covariances, can be initialized, converged and adapted to characteristics of the current network. In our experiments, distinct network traffic models are simulated in comparison with pathChirp and one Republic of China patent. The corresponding estimation results with respect to network information are also exhibited in the real networks.","Title: A Multiple Layered Audiovisual Streaming System Using the Two-Phase Synchronization and FGS/BSAC Techniques\nYear: 2008\n\nAbstract: For a ubiquitous multimedia streaming, an adaptive multimedia streaming scheme with multiple layered audiovisual (AV) coding is required over heterogeneous networks. This paper proposes a multiple layered audiovisual streaming scheme denoted ML-AVSS to deliver layered audiovisual data. Fine-granular scalability (FGS) and bit sliced arithmetic coding (BSAC) techniques are used to segment video and audio data into individual base-layer and multiple enhancement-layer bitstreams. With advantages of layered coding, two phases of streaming synchronization, including a human-perceptual based transmission scheme, de-jitter procedure, conditional retransmission and play- out synchronization, are proposed to transmit hybrid multiple layered audiovisual bitstreams. Experiment results show that the proposed ML-AVSS is a feasible streaming scheme to overcome challenges of the ubiquitous multimedia streaming, e.g., constrained available bandwidth, quality degradation, unsmooth playback, etc.","Title: A Navigation System for Brain Surgery Using Computer Vision Technology\nYear: 2008\n\nAbstract: In this paper, a surgical navigation system based on stereo-vision has been proposed. With the help of a projector, surface point data of a patient are firstly captured from two cameras by using the stereo-vision technique. Next, these point data is then registered by another surface point data obtained from the patient's pre-stored CT images using Feature-added ICP algorithm. For surgical navigation, a stereo-vision-based tracker is also designed in this system. In this manner, the anatomical information obtained from CT is fused on the images captured by the cameras and the tracker can be mounted to any surgical device for further surgical applications. Compared to conventional image guided surgeries, the proposed system has the advantage of fusing the visual and anatomical information such that it is more accurate and convenient.","Title: Efficient obstacle-avoiding rectilinear steiner tree construction\nYear: 2007\n\nAbstract: Given a set of pins and a set of obstacles on a plane, an obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) connects these pins, possibly through some additional points (called Steiner points), and avoids running through any obstacle to construct a tree with a minimal total wirelength. The OARSMT problem becomes more important than ever for modern nanometer IC designs which need to consider numerous routing obstacles incurred from power networks, prerouted nets, IP blocks, feature patterns for manufacturability improvement, antenna jumpers for reliability enhancement, etc. Consequently, the OARSMT problem has received dramatically increasing attention recently. Nevertheless, considering obstacles significantly increases the problem complexity, and thus most previous works suffer from either poor quality or expensive running time. Based on the obstacle-avoiding spanning graph (OASG), this paper presents an efficient algorithm with some theoretical optimality guarantees for the OARSMT construction. Unlike previous heuristics, our algorithm guarantees to find an optimal OARSMT for any 2-pin net and many higher-pin nets. Extensive experiments show that our algorithm results in significantly shorter wirelengths than all state-of-the-art works.","Title: Efficient provably good OPC modeling and its applications to interconnect optimization\nYear: 2010\n\nAbstract: Optical Proximity Correction (OPC) is the most popular technique to handle design shape distortions arising from subwavelength lithography. Existing OPC models are typically very computationally expensive and thus not efficient to be incorporated for layout optimization. In this paper, we present an efficient, yet sufficiently accurate OPC cost model which can predict the optimal location of a wire segment for OPC optimization and give an upper bound of the interference amount, guaranteeing that the interference amount is never underestimated. Based on this cost model, we propose an OPC-aware wire perturbation algorithm for post-layout interconnect optimization. We show that the effects of wire perturbation have the concavity or monotonicity property which can dramatically reduce the search space for finding the optimal location of each wire for OPC optimization. Further, we can incrementally update the OPC cost of a wire by recomputing only the affected wires because of the property of superposition of our model. Experimental results show that our algorithm can efficiently obtain much better OPC results than a state-of-the-art OPC-friendly router, based on a leading commercial OPC tool.","Title: A Novel 4-D Perceptual Quantization Modeling for H.264 Bit-Rate Control\nYear: 2007\n\nAbstract: Bit-rate control plays a major role In video coding and multimedia streaming. A well-designed bit-rate control mechanism can achieve line visual qualities and avoid network congestion over a time-varying channel. This paper proposes an H.264 bit-rate control using a 4D perceptual quantization modeling (PQrc), including two major encoding modules: the perceptual frame-level bit-allocation using a 1D temporal pattern and the macroblock-level quantizer decision using a 3D rate pattern. The temporal pattern is used to predict frame complexity and determine proper budget bits further. The rate pattern is depicted as a bit-complexity-quantization (B.C.Q.) model, in which a tangent slope of a B.C.Q. curve is a piece of unique information to find a proper quantizer. For newly generated video clips, the B.C.Q. model is updated continuously using a weighted least-square estimation. In comparison with the latest H.264 JM10.2, our experiment results show that the proposed PQrc can: 1) keep stable buffer fullness and 2) improve the SNR quality and control accuracy effectively.","Title: Simultaneous OPC- and CMP-aware routing based on accurate closed-form modeling\nYear: 2013\n\nAbstract: As the process technology advances to the nanometer nodes, Optical Proximity Correction (OPC) is the most popular Resolution-Enhancement Technique (RET) in industry for subwavelength lithography, and the inter-level dielectric (ILD) thickness variation caused by the planarization step of the Chemical-Mechanical Polishing (CMP) process also plays a key role for interconnect yield. Considering the OPC and CMP effects simultaneously during the routing stage can significantly alleviate the width and thickness variations (and thus the whole 3D geometry variations) of post-layout RET and CMP operations. In this paper, we first present an efficient, yet sufficiently accurate closed-form formula for printed width computation and dummy-insertion-aware routing cost derivation. The formula provides a cost modeling for post-layout OPC and CMP optimization during routing. Incorporating the OPC and CMP costs, the router can be guided to optimize the effects of layout correction and planarization. Compared with the state-of-the-art OPC-friendly router, QL-MGR (which does not consider CMP), the experimental results show that our approach can achieve respective 19% and 6% reductions in the maximum and average layout distortions. Compared with the state-of-the-art CMP-aware router, TTR (which does not consider OPC), the experimental results show that our approach can achieve respective 19% and 25% reductions in the peak-to-peak thickness and thickness variance. These results indicate that our simultaneous OPC- and CMP-aware router contributes a significant improvement for layout integrity.","Title: Security-aware mapping for CAN-based real-time distributed automotive systems\nYear: 2013\n\nAbstract: Cyber-security is a rising issue for automotive electronic systems, and it is critical to system safety and dependability. Current in-vehicles architectures, such as those based on the Controller Area Network (CAN), do not provide direct support for secure communications. When retrofitting these architectures with security mechanisms, a major challenge is to ensure that system safety will not be hindered, given the limited computation and communication resources. We apply Message Authentication Codes (MACs) to protect against masquerade and replay attacks on CAN networks, and propose an optimal Mixed Integer Linear Programming (MILP) formulation for solving the mapping problem from a functional model to the CAN-based platform while meeting both the security and the safety requirements. We also develop an efficient heuristic for the mapping problem under security and safety constraints. To the best of our knowledge, this is the first work to address security and safety in an integrated formulation in the design automation of automotive electronic systems. Experimental results of an industrial case study show the effectiveness of our approach.","Title: Security-Aware Modeling and Efficient Mapping for CAN-Based Real-Time Distributed Automotive Systems\nYear: 2015\n\nAbstract: Security has become a critical issue for automotive electronic systems. To protect against attacks, security mechanisms have to be applied, but the overhead of those mechanisms may impede system performance and cause violations of design constraints. To remedy this problem, we proposed an integrated mixed integer linear programming (MILP) formulation that is the first to address both security and safety constraints during system mapping for controller area network (CAN) based systems . However, its signal-based security constraints do not fully reflect real security requirements, and its objective function is to minimize functional path latencies rather than minimize security risk. Furthermore, its MILP-based approach has high computation complexity. In this work, we present a new formulation that defines path-based security constraints and minimizes security risk directly, and propose a new heuristic algorithm to solve the formulation efficiently. Experiments on an industrial example show that our new algorithm achieves comparable solution quality as the MILP-based approach with much better efficiency.","Title: Intra-vehicle network routing algorithm for wiring weight and wireless transmit power minimization\nYear: 2015\n\nAbstract: As the complexity of vehicular distributed systems increases rapidly, several hundreds of devices (sensors, actuators, etc.) are being placed in a modern automotive system. With the increase in wiring cables connecting these devices, the weight of a car increases significantly, which degrades the fuel efficiency in driving. In order to reduce the weight of a car, wireless communication has been introduced to replace wiring cables between some devices. However, the extra energy consumption for packet transmissions by wireless devices requires frequent maintenance, e.g., recharging of batteries. In this paper, we propose an intra-vehicle network routing algorithm to simultaneously minimize the wiring weight and the transmit power for wireless communication. Experimental results show that the proposed method can effectively minimize the wiring weight and the transmit power for wireless communication.","Title: Security-aware mapping for TDMA-based real-time distributed systems\nYear: 2014\n\nAbstract: Cyber-security has become a critical issue for real-time distributed embedded systems in domains such as automotive, avionics, and industrial automation. However, in many of such systems, tight resource constraints and strict timing requirements make it difficult or even impossible to add security mechanisms after the initial design stages. To produce secure and safe systems with desired performance, security must be considered together with other objectives at the system level and from the beginning of the design. In this paper, we focus on security-aware design for Time Division Multiple Access (TDMA) based real-time distributed systems. The TDMA-based protocol we consider is an abstraction of many time-triggered protocols that are being adopted in various safety-critical systems for their more predictable timing behavior, such as FlexRay, Time-Triggered Protocol, and Time-Triggered Ethernet. To protect against attacks on TDMA-based real-time distributed systems, we apply a message authentication mechanism with time-delayed release of keys, which provides a good balance between security and computational overhead but needs sophisticated network scheduling to ensure that the increased latencies due to delayed key releases will not violate timing requirements. We propose formulations and an algorithm to optimize the task allocation, priority assignment, network scheduling, and key-release interval length during the mapping process, while meeting both security and timing requirements. Experimental results of an automotive case study and a synthetic example show the effectiveness and efficiency of our approach.","Title: Buffered clock tree synthesis considering self-heating effects\nYear: 2014\n\nAbstract: A clock tree typically consumes substantial dynamic power, and thus the considerable heat generated by itself can cause serious clock-skew variations. In this paper, we propose a self-heating-aware buffered clock tree synthesis flow. A mixed integer linear programming (MILP) formulation is proposed to simultaneously model heat spreading, place buffers, and determine a temperature-aware clock tree topology. The formulation is then transformed into a succession of low-complexity feasibility problems to further reduce the runtime. In addition, a fast superposition approach is proposed to incrementally update thermal profiles to reduce simulation time. Experimental results show that our synthesis flow can achieve averagely 50.57% worst-case clock skew reduction, compared with the original symmetrical clock tree.","Title: Efficient Wire Routing and Wire Sizing for Weight Minimization of Automotive Systems\nYear: 2015\n\nAbstract: As the complexities of automotive systems increase, designing a system is a difficult task that cannot be done manually. In this paper, we focus on wire routing and wire sizing for weight minimization to deal with more and more connections between devices in automotive systems. The wire routing problem is formulated as a minimal Steiner tree problem with capacity constraints, and the location of a Steiner vertex is selected to add a splice which is used to connect more than two wires. We modify the KMB algorithm [12] to efficiently construct Steiner trees and propose an Integer Linear Programming (ILP) formulation to relocate Steiner vertices and satisfy capacity constraints. The ILP formulation is relaxed to a Linear Programming (LP) formulation which has the same optimal objective and can be solved more efficiently. Besides wire routing, wire sizing is also performed to satisfy resistance constraints and minimize the total wiring weight. To the best of our knowledge, this is the first work in the literature to formulate the automotive routing problem as a minimal Steiner tree problem with capacity constraints and perform wire routing and wire sizing for weight minimization. An industrial case study shows the effectiveness and efficiency of our algorithm which provides an efficient, flexible, and scalable approach for the design optimization of automotive systems.","Title: The dynamic influence of emotions on game-based creativity: An integrated analysis of emotional valence, activation strength, and regulation focus.\nYear: 2016\n\nAbstract: Emotion has been identified as an important predictor of creativity, but little attention has been put on investigating how emotion, especially that considers regulation focus, may dynamically influence male and female students' creativity in game-based situations. To explore the dynamic relationship between various types of emotions and creativity during game playing, 266 college students were included and the Creativity Game-based Evaluation System (CGES) was developed in this study. Four types of emotions integrating perspectives of valence (positive vs. negative), activation (high vs. low), and regulatory focus (prevention vs. promotion) were investigated in this study: the positive-low activation-prevention emotion (P-L-Pre) (calm and relaxed), the positive-high activation-promotion emotion (P-H-Pro) (happy and elated), the negative-high activation-prevention emotion (N-H-Pre) (nervous and anxious), and the negative-high activation-promotion emotion (N-H-Pro) (frustrated and angry). The results revealed that, although there was a slight gender difference in game-based creativity, the prediction patterns of emotions in game-based creativity were very similar among participants with different genders. Specifically, emotions during game playing can better predict creativity than those of the baseline; moreover, the P-H-Pro emotion can facilitate performance on creativity, whereas the N-H-Pro emotion can decrease creativity performance. Thus, providing appropriate challenges to induce highly-activated and promotion-focused positive emotions are critical for the success of games designed to improve creativity.","Title: Security-Aware Design Methodology and Optimization for Automotive Systems\nYear: 2015\n\nAbstract: In this article, we address both security and safety requirements and solve security-aware design problems for the controller area network (CAN) protocol and time division multiple access (TDMA)-based protocols. To provide insights and guidelines for other similar security problems with limited resources and strict timing constraints, we propose a general security-aware design methodology to address security with other design constraints in a holistic framework and optimize design objectives. The security-aware design methodology is further applied to solve a security-aware design problem for vehicle-to-vehicle (V2V) communications with dedicated short-range communication (DSRC) technology. Experimental results demonstrate the effectiveness of our approaches in system design without violating design constraints and indicate that it is necessary to consider security together with other metrics during design stages.","Title: Invited - Cooperation or competition?: coexistence of safety and security in next-generation ethernet-based automotive networks\nYear: 2016\n\nAbstract: Safety is traditionally the most relevant property for automotive systems, and it is further enhanced by Advanced Driver Assistance Systems (ADAS) in modern automotive systems. To support ADAS and other advanced autonomous functions, automotive electronic systems become more distributed and connected than ever, with in-vehicle architecture or Vehicle-to-X (V2X) communication. These connections create a variety of interfaces which become breeding grounds for security attacks. Accordingly, security becomes a rising issue for automotive systems. In this paper, we address safety and security together, especially their interactions, in Ethernet-based automotive networks which are believed to be the next-generation automotive networks since they are able to provide high bandwidths, certain timing guarantees, and well-developed technologies. We discuss the interactions between safety and security in three problems: secret key management, frame replication and elimination, and Virtual Local Area Network (VLAN) segmentation. We demonstrate that safety and security can work together, but sometimes there is a trade-off between them. This indicates that safety cannot stand alone without considering security, and network security is a necessary component of system security. Towards safer and securer automotive systems, safety and security should be considered together during design stages of automotive systems.","Title: Next Generation Automotive Architecture Modeling and Exploration for Autonomous Driving\nYear: 2016\n\nAbstract: To support emerging applications in autonomous and semi-autonomous driving, next-generation automotive systems will be equipped with an increasing number of heterogeneous components (sensors, actuators and computation units connected through various buses), and have to process a high volume of data to percept the environment accurately and efficiently. Challenges for such systems include system integration, prediction, verification and validation. In this work, we propose an architecture modeling and exploration framework for evaluating various software and hardware architecture options. The framework will facilitate system integration and optimization, and enable validation of various design metrics such as timing, reliability, security and performance.","Title: CONVINCE: a cross-layer modeling, exploration and validation framework for next-generation connected vehicles.\nYear: 2016\n\nAbstract: Next-generation autonomous and semi-autonomous vehicles will not only precept the environment with their own sensors, but also communicate with other vehicles and surrounding infrastructures for vehicle safety and transportation efficiency. The design, analysis and validation of various vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) applications involve multiple layers, from V2V/V2I communication networks down to software and hardware of individual vehicles, and concern with stringent requirements on multiple metrics such as timing, security, reliability and fault tolerance. To cope with these challenges, we have been developing CONVINCE, a cross-layer modeling, exploration and validation framework for connected vehicles. The framework includes mathematical models, synthesis and validation algorithms, and a heterogeneous simulator for inter-vehicle communications and intra-vehicle software and hardware in a holistic environment. It explores various design options with respect to constraints and objectives on system safety, security, reliability, cost, etc. A V2V application is used in the case study to demonstrate the effectiveness of the proposed framework.","Title: Platform-Based Plug and Play of Automotive Safety Features: Challenges and Directions (Invited Paper).\nYear: 2016\n\nAbstract: Optional software-based features are increasingly becoming an important cost driver in automotive systems. These include features pertaining to active safety, infotainment, etc. Currently, these optional features are integrated into the vehicles at the factory during assembly. This severely restricts the flexibility of the customer to select and use features on-demand and therefore, the customer will either have to be satisfied with an available set of feature options or pre-order a car with the required features from the manufacturer resulting in considerable delay. In order to increase flexibility and reduce the delay, it is necessary to provide the option to configure the vehicle on-demand at the dealership or remotely. In this paper, we present our vision and challenges involved in developing a platform infrastructure that allows on-demand deployment of automotive safety features and ensures their correct execution.","Title: Design space exploration for deterministic ethernet-based architecture of automotive systems\nYear: 2016\n\nAbstract: Time Triggered Ethernet (TTE) is a time-triggered network technology with large bandwidth and services for deterministic, safety-relevant communication. Hence, it has gained increasing attention from domains such as aerospace, automotive and industrial applications. In this work, we aim to solve the problem of task mapping and communication scheduling in automotive design. The system model is a dataflow task communication model mapped to a target architecture based on TIE. The design variables are the mapping of tasks onto the end systems in the architecture and the scheduling of all frames. The constraints include the schedulability of tasks and signals, as well as the latency constraints of the critical paths as specified by the designer. It can be shown that the problem is NP· hard. Therefore, we develop a heuristic to solve this problem. The heuristic contains four steps and all of them (except scheduling) are formulated using Integer Linear Programming (ILP). We present experimental results on an industrial benchmark and two synthetic benchmarks which show the efficiency and scalability of our approach.","Title: An Amanat-Based Multi-party Certification Protocol for Outsourced Software in Automotive Systems\nYear: 2016\n\nAbstract: As autonomous features advance, it is believed that most behaviors, including safety-critical functions, of future automotive systems will be defined by software. Due to the safety-critical nature, correctness and quality of automotive software draw more and more concerns, and software certification should integrate verification, simulation, and testing results in systematic and rigorous ways to prove the fulfillment of governments' regulations, reduce system designers' liability, and enhance customers' confidence. Expecting that software certification will become a necessary step in future automotive design, we resolve a conflict between certification issuers and software suppliers and developers in this paper. Based on the Amanat protocol [6], we address its challenges in the automotive domain and propose a protocol which guarantees authenticity to certification issuers and confidentiality to software suppliers and developers. Authenticity means that only authenticated results from compilers and analysis tools (verification, simulation, and/or testing) are considered by the certification issuers in the certification process, and confidentiality means that sensitive source codes of the software suppliers and developers are not released to certification issuers. The proposed protocol is an important step towards the realization of practical automotive software certification.","Title: Delay-Bounded Intravehicle Network Routing Algorithm for Minimization of Wiring Weight and Wireless Transmit Power.\nYear: 2017\n\nAbstract: As the complexity of vehicular distributed systems increases rapidly, several hundreds of devices are being placed in a modern automotive system. With the increase in wiring cables connecting these devices, the weight of a vehicle increases significantly and degrades the fuel efficiency during driving. In order to reduce the wiring weight, wireless communication has been introduced to replace wiring cables between some devices. However, the extra energy consumption and the transmission delay due to wireless communication need to be considered because they may result in frequent maintenance (e.g., recharging of batteries) and deadline violation, respectively. In this paper, we propose an intravehicle network routing algorithm to simultaneously minimize the wiring weight and the wireless transmit power while considering the transmission delay in automotive systems. Experimental results show that the proposed method can effectively minimize the wiring weight and the wireless transmit power and satisfy other design constraints.","Title: Accurate High-level Modeling and Automated Hardware/Software Co-design for Effective SoC Design Space Exploration.\nYear: 2017\n\nAbstract: A desirable feature of a development tool for SoC design is that, given the important applications in the domain to be targeted by the SoC, a powerful hardware-software partitioning engine is available to determine which function(s) shall be mapped to hardware. However, to provide high-quality partitioning, this engine must be able to consider a rich design space of possible alternate hardware and software implementations for each program region candidate for hardware acceleration, in turn making the task of finding the optimal mapping very difficult given the number of design points to consider and the need for accurate modeling of latency, power and area. In this work we propose a novel framework to enable hardware acceleration of performance-critical parts of an application, by addressing the problem of hardware/software partitioning under power and area constraints to minimize the overall program latency. Our flow is based on the LLVM compiler, and focuses on building a scalable compile-time partitioning algorithm while considering large sets of alternative hardware and software implementations for a particular region. To this end we develop a hybrid approach based on mixing semi-random selection of hardware design points and an Integer Linear Programming formulation of the mapping decision, along with iterative refinements of the solution. Experimental results demonstrate the capability of our approach to consider complex designs and yet output near-optimal partitioning decision. Our package is named RIP (Randomized ILP-based Partitioning), and is open source to benefit the research community.","Title: Delay-Aware Design, Analysis and Verification of Intelligent Intersection Management\nYear: 2017\n\nAbstract: With the rapid advancement of autonomous driving and vehicular communication technology, intelligent intersection management has shown great promise in improving transportation efficiency. In a typical intelligent intersection, an intersection manager communicates with autonomous vehicles wirelessly and schedules their crossing of the intersection. Previous system designs, however, do not address the possible communication delays due to network congestion or security attacks, and could lead to unsafe or deadlocked systems. In this work, we propose a delay- tolerant protocol for intelligent intersection management, and develop a modeling, simulation and verification framework for analyzing the protocol's safety, liveness and performance. Experiments demonstrate the advantages of our proposed protocol over traditional traffic light control, and more importantly, demonstrate the importance and effectiveness of using this framework to address timing (delay) in vehicular network applications. This work is the first step towards a comprehensive delay-aware design and verification framework for practical vehicular network applications.","Title: Principles for Systematic Development of an Assurance Case Template from ISO 26262\nYear: 2017\n\nAbstract: A failure in a critical system can cause death, injury, financial loss, and environmental damage. To develop safe and trustworthy systems, we need to plan the development and assessment of system functionality in advance. Assurance Cases are a generalization of Safety Cases, and are gaining momentum as a preferred way of demonstrating assurance of critical properties in complex software-intensive systems. To cope with the lack of standardized assurance structures, and to encourage safety assessment prior to development, we previously proposed the use of an assurance case template. The principles presented here can be used to build an assurance case template that complies with the functional safety standard, ISO 26262 in a cost-effective way. In the future, such principles may lead to semi-automated development of these templates.","Title: Reliable Intersection Control in Non-cooperative Environments.\nYear: 2018\n\nAbstract: We propose a reliable intersection control mechanism for strategic autonomous and connected vehicles (agents) in non-cooperative environments. Each agent has access to his/her earliest possible and desired passing times, and reports a passing time to the intersection manager, who allocates the intersection temporally to the agents in a First-Come-First-Serve basis. However, the agents might have conflicting interests and can take actions strategically. To this end, we analyze the strategic behaviors of the agents and formulate Nash equilibria for all possible scenarios. Furthermore, among all Nash equilibria we identify a socially optimal equilibrium that leads to a fair intersection allocation, and correspondingly we describe a strategy-proof intersection mechanism, which achieves reliable intersection control such that the strategic agents do not have any incentive to misreport their passing times strategically.","Title: Distributed Conflict Resolution for Connected Autonomous Vehicles.\nYear: 2018\n\nAbstract: This paper proposes a novel communication-enabled distributed conflict resolution mechanism in order for a group of connected autonomous vehicles to navigate safely and efficiently in intersections without any traffic manager. The conflict resolution strategy for individual vehicle is decoupled temporally. In a decision maker, the vehicle computes the desired time slots to pass the conflict zones ...","Title: Runtime monitoring for safety of intelligent vehicles\nYear: 2018\n\nAbstract: Advanced driver-assistance systems (ADAS), autonomous driving, and connectivity have enabled a range of new features, but also made automotive design more complex than ever. Formal verification can be applied to establish functional correctness, but its scalability is limited due to the sheer complexity of a modern automotive system. To manage high complexity and limited development resources, one alternative is to apply runtime monitoring techniques to detect when the system transitions into an unsafe state (i.e., one where it violates a critical safety requirement). In this paper, we report on our experience integrating runtime monitoring into a development workflow and present practical design considerations on languages and tools from an industrial perspective. Using signal temporal logic (STL) [12] and the Breach [6] monitoring tool, we perform a case study showing how monitoring can be used to detect undesirable interactions between two ADAS features called Cooperative Pile-up Mitigation System (CPMS) and False-Start Prevention System (FPS). This is an initial step to utilize runtime monitoring to achieve high assurance in the design of intelligent vehicles.","Title: Threat Detection for Collaborative Adaptive Cruise Control in Connected Cars.\nYear: 2018\n\nAbstract: We study collaborative adaptive cruise control as a representative application for safety services provided by autonomous cars. We provide a detailed analysis of attacks that can be conducted by a motivated attacker targeting the collaborative adaptive cruise control algorithm, by influencing the acceleration reported by another car, or the local LIDAR and RADAR sensors. The attacks have a strong impact on passenger comfort, efficiency and safety, with two of such attacks being able to cause crashes. We also present two detection methods rooted in physical-based constraints and machine learning algorithms. We show the effectiveness of these solutions through simulations and discuss their limitations.","Title: Distributed file allocation using matching game in mobile fog-caching service network\nYear: 2018\n\nAbstract: The fog-caching enabled radio access network has been identified as an effective solution to reduce content down-loading latency of mobile users (MUs). The quality of service (QoS) can be dramatically enhanced by caching popular files into the storages of femto-cell access points (FAPs) adjacent to MUs. However, file allocation is challenging when the mobility of users is considered. In this scenario, the serving users of each FAP are not fixed, and they vary from time to time. In order to address this, we design distributed algorithms, using two separate matching games, with the aim to minimize the system file downloading latency. To be specific, we first allocate files to each FAP and then associate an MU with a proper FAP, considering the mobility of users. At last, numerical results are presented to demonstrate the effectiveness of the proposed algorithms. It is verified that the proposed algorithms outperform the benchmark in terms of achieving a lower transmission delay.","Title: Bandwidth Optimal Data/Service Delivery for Connected Vehicles via Edges\nYear: 2018\n\nAbstract: The paradigm of connected vehicles is fast gaining lot of attraction in the automotive industry. Recently, a lot of technological innovation has been pushed through to realize this paradigm using vehicle to cloud (V2C), infrastructure (V2I) and vehicle (V2V) communications. This has also opened the doors for efficient delivery of data/service to the vehicles via edge devices that are closer to the vehicles. In this work, we propose an optimization framework that can be used to deliver data/service to the connected vehicles such that a bandwidth cost objective is optimized. For the first time, we also integrate a vehicle flow model in the optimization framework to model the traffic flow in the coverage area of the edges. Using the optimization framework, we study the variation of the optimal bandwidth cost for varying problem sizes and vehicle flow model parameter values for both data and service delivery.","Title: Property-Driven Runtime Resolution Of Feature Interactions\nYear: 2018\n\nAbstract: The feature interaction problem occurs when two or more features interact and possibly conflict with each other in unexpected ways, resulting in undesirable system behaviors. Common approaches to resolving feature interactions are based on priorities, which are ineffective in scenarios where the set of features may evolve past the design phase, and where desirability of features may change dynamically depending on the state of the environment. This paper introduces a property-driven approach to feature-interaction resolution, where a desired system property is leveraged to determine which feature action should be enabled at a given context. Compared to existing approaches, our approach is capable of (1) providing resolutions even if the system evolves with new or modified features, and (2) handling complex resolution scenarios where the preference of one feature over the others may change dynamically. We demonstrate the effectiveness of our approach through a case study involving resolution of safety-critical features in an intelligent vehicle.","Title: Network and system level security in connected vehicle applications\nYear: 2018\n\nAbstract: Connected vehicle applications such as autonomous intersections and intelligent traffic signals have shown great promises in improving transportation safety and efficiency. However, security is a major concern in these systems, as vehicles and surrounding infrastructures communicate through ad-hoc networks. In this paper, we will first review security vulnerabilities in connected vehicle applications. We will then introduce and discuss some of the defense mechanisms at network and system levels, including (1) the Security Credential Management System (SCMS) proposed by the United States Department of Transportation, (2) an intrusion detection system (IDS) that we are developing and its application on collaborative adaptive cruise control, and (3) a partial consensus mechanism and its application on lane merging. These mechanisms can assist to improve the security of connected vehicle applications.","Title: Quotient for Assume-Guarantee Contracts.\nYear: 2018\n\nAbstract: We introduce a novel notion of quotient set for a pair of contracts and the operation of quotient for assume-guarantee contracts. The quotient set and its related operation can be used in any compositional methodology where design requirements are mapped into a set of components in a library. In particular, they can be used for the so called missing component problem, where the given components are not capable of discharging the obligations of the requirements. In this case, the quotient operation identifies the contract for a component that, if added to the original set, makes the resulting system fulfill the requirements.","Title: Platform-Independent QoS Parameters and Primitive APIs for Automotive Software\nYear: 2018\n\nAbstract: Modern ITS (Intelligent Transportation System) applications are becoming increasingly sophisticated and diverse, following the growing trends of connectivity and autonomous driving. For example, a vehicle can be equipped with advanced sensors (e.g., LIDAR, camera or radar) to perform complex driving maneuvers by itself and/or communicate with other vehicles or road-side infrastructures to assist drivers in safer driving. Since the operation of an automotive application is closely tied to the underlying platform characteristics, it requires significant integration effort when the application needs to operate on a wide range of platforms such as other vehicle types or road-side infrastructures. To reduce such effort, we propose a method to implement automotive applications in a platform-independent way. Our approach is to define the automotive domain-specific QoS (Quality of Service) parameters that allow an application to specify the expected quality of sensor input or actuator output independent of a particular platform for safe operation. The application interacts with a platform through several primitive APIs to inform QoS requirements, to read/write sensors/actuators values according to the specified QoS, and to handle exceptions upon any QoS violation. We implement a multi-mode ACC (Adaptive Cruise Control) application on a RC-car platform to demonstrate how an automotive application can be implemented based on the proposed QoS parameters and primitives.","Title: Poster: Formal QoS Compatibility Verification for Components on Time-Sensitive Networking\nYear: 2018\n\nAbstract: System integration has became more challenging than ever. In this poster, we propose to use a formal approach to verify the Quality of Service (QoS) compatibility of components connected by the Time-Sensitive Networking (TSN) [6]. We demonstrate that the formal approach, if realized, is applicable to various stages including specification definition of components to be developed, integration with existing components, runtime monitoring with adaptive components, and maintenance of components.","Title: Information-Driven Autonomous Intersection Control via Incentive Compatible Mechanisms\nYear: 2019\n\nAbstract: We propose a new information-driven intersection control to enhance the quality of transportation by using communication between vehicles and roadside units. The state-of-the-art solutions for intersection control only have access to the sensor data that is collected by vehicles or roadside units. However, congestion at intersections can have different impact on different drivers, and yet such an impact cannot be measured by sensors. An effective intersection control can consider such driver-exclusive differences based on the information reported by the drivers, which can substantially enhance the quality of transportation. However, such information is driver-exclusive, i.e., not verifiable easily, and therefore prone to be misreported strategically. We propose strategy-proof intersection control addressing such issues via a payment-based incentive-compatible mechanism. Particularly, vehicles at close proximity of the intersection report their driver-exclusive utility functions that they want to maximize (not necessarily truthfully), while the roadside unit seeks to maximize the sum of those utilities, i.e., social welfare, by scheduling intersection usage and charging each vehicle an amount of time-tokens corresponding to their impact on other drivers. This approach, based on the Vickrey-Clarke-Groove mechanism, \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">guarantees</italic>\n truthful utility reporting by the vehicles and, correspondingly, \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">maximizes</italic>\n the social welfare. The proposed scheme is universal such that it can be implemented based on various utility functions or intersection control constraints. We also provide a practical implementation to analyze the performance via numerical simulations.","Title: Timing and security analysis of VANET-based intelligent transportation systems: (Invited paper).\nYear: 2017\n\nAbstract: With the fast development of autonomous driving and vehicular communication technologies, intelligent transportation systems that are based on VANET (Vehicular Ad-Hoc Network) have shown great promise. For instance, through V2V (Vehicle-to-Vehicle) and V2I (Vehicle-to-Infrastructure) communication, intelligent intersections allow more fine-grained control of vehicle crossings and significantly enhance traffic efficiency. However, the performance and safety of these VANET-based systems could be seriously impaired by communication delays and packet losses, which may be caused by network congestion or by malicious attacks that target communication timing behavior. In this paper, we quantitatively model and analyze some of the timing and security issues in transportation networks with VANET-based intelligent intersections. In particular, we demonstrate how communication delays may affect the performance and safety of a single intersection and of multiple interconnected intersections, and present our delay-tolerant intersection management protocols. We also discuss the issues of such protocols when the vehicles are non-cooperative and how they may be addressed with game theory.","Title: Improving Efficiency Of Autonomous Vehicles By V2v Communication\nYear: 2018\n\nAbstract: Autonomous vehicles are widely regarded as a promising technology to improve the safety of transportation systems. However, the efficiency of vehicles may be compromised to ensure safety when there are large uncertainties in perception and prediction of the behaviors of other road participants due to limitations in sensors. To remedy this problem, vehicle to vehicle (V2V) communication is applied to improve efficiency of autonomous vehicles during interactions with other vehicles. By requiring the vehicles to communicate their intentions with one another, the efficiency of the vehicles can be improved in terms of smaller variations in their speed profiles and smaller delay as demonstrated in the simulations.","Title: From Electronic Design Automation to Automotive Design Automation.\nYear: 2019\n\nAbstract: Advanced driver assistance systems (ADAS), autonomous functions, and connected applications bring a revolution to automotive systems, but they also make automotive design, especially software and electronics, more complex than ever. The complexity introduces significant challenges to automotive industry, and thus design automation, model-based design, and platform-based design can assist system designers to verify design correctness, improve design quality, accelerate design development, reduce design cost, and prevent redesign or recall. Sharing similar concepts with electronic design automation, automotive design automation can be categorized into three core parts: modeling, design (including synthesis and optimization), and analysis (including verification, simulation, and testing).\n\nIn this talk, we first go through some examples of modeling, design, and analysis in both of electronic design automation and automotive design automation. Next, we present two routing problems, one applicable to circuit physical design and automotive harness design and the other one applicable to microfluidic biochip design and intersection management, and discuss their similarities and differences. Then, we bring out four design-time problems in the automotive domain: (1) placement which allocates tasks onto automotive systems, edges, and the cloud, (2) verification which checks the compatibility of automotive sub-systems, (3) software integrity which aims to comply with an automotive functional safety standard, ISO 26262, and (4) security-aware design and analysis which provide decisions at the early stages in the V-model.\n\nBesides the existing solutions and research challenges of these problems, how the techniques in electronic design automation can facilitate addressing these problems is also covered. We believe that the techniques can not only contribute solutions to integrated circuit design and automotive design but also give insights to the design of embedded systems, cyber-physical systems, and other complex systems.","Title: Vehicle Sequence Reordering With Cooperative Adaptive Cruise Control\nYear: 2019\n\nAbstract: With Cooperative Adaptive Cruise Control (CACC) systems, vehicles are allowed to communicate and cooperate with each other to form platoons and improve the traffic throughput, traffic performance, and energy efficiency. In this paper, we take into account the braking factors of different vehicles so that there is a desired platoon sequence which minimizes the platoon length. We formulate the vehicle sequence reordering problem and propose an algorithm to reorder vehicles to their desired platoon sequence.","Title: A Game Theoretical Error-Correction Framework for Secure Traffic-Sign Classification.\nYear: 2019\n\nAbstract: We introduce a game theoretical error-correction framework to design classification algorithms that are reliable even in adversarial environments, with a specific focus on traffic-sign classification. Machine learning algorithms possess inherent vulnerabilities against maliciously crafted inputs especially at high dimensional input spaces. We seek to achieve reliable and timely performance in classification by redesigning the input space physically to significantly lower dimensions. Traffic-sign classification is an important use-case enabling the redesign of the inputs since traffic-signs have already been designed for their easy recognition by human drivers. We encode the original input samples to, e.g., strings of bits, through error-correction methods that can provide certain distance guarantees in-between any two different encoded inputs. And we model the interaction between the defense and the adversary as a game. Then, we analyze the underlying game using the concept of hierarchical equilibrium, where the defense strategies are designed by taking into account the best possible attack against them. At large scale, for computational simplicity, we provide an approximate solution, where we transform the problem into an efficient linear program with substantially small size compared to the original size of the entire input space. Finally, we examine the performance of the proposed scheme over different traffic-sign classification scenarios.","Title: Human-Robot Cooperation for Autonomous Vehicles and Human Drivers: Challenges and Solutions\nYear: 2021\n\nAbstract: Connected and automated vehicles (CAVs) are becoming increasingly feasible, and these vehicles are expected to enhance road safety, traffic throughput, energy efficiency, and human comfort, especially at road intersections and for lane changing, merging, and unprotected turning maneuvers. However, there is likely to be a long transition period before human-driven vehicles are completely replaced b...","Title: Efficient Mandatory Lane Changing of Connected and Autonomous Vehicles\nYear: 2021\n\nAbstract: In a mandatory lane-changing scenario, vehicles need to move to their target lanes before the end of a road segment. Mandatory lane changing usually happens near a highway ramp, and it is one major source of traffic congestion and delay. The advance of connected and autonomous vehicles supports to solve the problem in a centralized and precise way. We formulate a mandatory lane-changing problem and propose a Mixed-Integer Linear Programming (MILP) approach to find an optimal solution. We then propose an MILP-based incremental-window algorithm to solve the problem efficiently. Experimental results show that the MILP-based incremental-window algorithm can take much less computation time and achieve almost the same solution quality, compared with the original MILP approach. The advantage of efficiency yet sufficient effectiveness matches the need of high-level control (decision of passing order) well.","Title: Compatibility Checking for Autonomous Lane-Changing Assistance Systems\nYear: 2022\n\nAbstract: Different types of lane-changing assistance systems are usually developed separately by different automotive makers or suppliers. A lane-changing model can meet its own requirements, but it may be incompatible with another lane-changing model. In this paper, we verify if two lane-changing models are compatible so that the two corresponding vehicles on different lanes can exchange their lanes successfully. We propose a methodology and an algorithm to perform the verification on the combinations of four lane-changing models. Experimental results demonstrate the compatibility (or incompatibility) between the models. The verification results can be utilized during runtime to prevent incompatible vehicles from entering a lane-changing road segment. To the best of our knowledge, this is the first work considering the compatibility issue for lane-changing models.","Title: Deadlock Analysis and Prevention for Intersection Management Based on Colored Timed Petri Nets\nYear: 2022\n\nAbstract: We propose a Colored Timed Petri Net (CTPN) based model for intersection management. With the expressiveness of the CTPN-based model, we can consider timing, vehicle-specific information, and different types of vehicles. We then design deadlock-free policies and guarantee deadlock-freeness for intersection management. To the best of our knowledge, this is the first work on CTPN-based deadlock analysis and prevention for intersection management.","Title: Deadlock Resolution for Intelligent Intersection Management with Changeable Trajectories\nYear: 2022\n\nAbstract: Intelligent intersection management aims to schedule vehicles so that vehicles can pass through an intersection efficiently and safely. However, inaccurate control, imperfect communication, and malicious information or behavior lead to robustness issues of intelligent intersection management. In this work, we focus on improving robustness against deadlocks by changing the trajectories of vehicles. To guarantee the resolvability of deadlocks, we limit the number of vehicles in an intersection to be smaller than or equal to an intersection-specific value called the maximal deadlock-free load. We develop an algorithm to compute the maximal deadlock-free load. We further reduce the computation time by computing the loads which are pessimistic (smaller) but still deadlock-free. Since the maximal deadlock-free load only depends on the given intersection, it can be integrated with different scheduling algorithms. Experimental results demonstrate that, by changing the trajectories of vehicles and limiting the number of vehicles under maximal deadlock-free loads, our approach can guarantee deadlock-freeness and maintain good traffic efficiency.","Title: Deep-Learning-Based Anomaly Detection for Lane-Changing Decisions\nYear: 2022\n\nAbstract: Vehicles can utilize their sensors or receive messages from other vehicles to acquire information about the surrounding environments. However, the information may be inaccurate, faulty, or maliciously compromised due to sensor failures, communication faults, or security attacks. The goal of this work is to detect if a lane-changing decision and the sensed or received information are anomalous. We develop three anomaly detection approaches based on deep learning: a classifier approach, a predictor approach, and a hybrid approach combining the classifier and the predictor. All of them do not need anomalous data nor lateral features so that they can generally consider lane-changing decisions before the vehicles start moving along the lateral axis. They achieve at least 82% and up to 93% F-1 scores against anomaly on data from Simulation of Urban MObility (SUMO) [1] and HighD [2]. We also examine system properties and verify that the detected anomaly includes more dangerous scenarios."],"string":"[\n \"Title: Calculate Golf Swing Trajectories from IMU Sensing Data\\nYear: 2012\\n\\nAbstract: In the process of sport learning, learners spend a lot of time on practicing in order to develop correct action habit. Take golf practice as an example. Without the supervising of coaches, novices may keep practicing wrong swing actions, and that will cost more time later on to correct the wrong habit. It would be helpful to let learners can be aware of incorrect swing actions in self-training. In this work, we propose an IMU-based solution to help learners by allowing them to review their swing trajectories and also learn key features of the swings. In the proposed system, an IMU composed of an accelerometer, a magnetometer and a gyroscope is installed on the golf club to collect inertial motion data. From the collected data, swing trajectories can be calculated and swing features can also be extracted.\",\n \"Title: Location Management of Correlated Mobile Users in the UMTS\\nYear: 2005\\n\\nAbstract: In this paper, we propose concurrently searching for correlated mobile users in mobile communications networks. Previous work either focuses on locating a single mobile user or assumes that the locations of mobile users are statistically independent. We first propose a mobility model in which the movements of mobile users are statistically correlated. Next, we use the theory of Markov chain to derive the joint probability density function of the locations of mobile users. In addition, we propose a novel approach to discover the correlations among the locations of mobile users without explicitly calculating the joint probability density function. Our simulation results indicate that exploring the correlations among the locations of mobile users could significantly reduce the average paging delay and increase the maximum stable throughput.\",\n \"Title: Cyber-Security for the Controller Area Network (CAN) Communication Protocol\\nYear: 2012\\n\\nAbstract: We propose a security mechanism to help prevent cyber-attacks (masquerade and replay) in vehicles with architecture based on Controller Area Network (CAN). We focus on CAN as it will likely continue being used in upcoming in-vehicle architectures. The CAN protocol contains no direct support for secure communications. Retrofitting the protocol with security mechanisms poses several challenges given the very limited data rates available (e.g., 500kbps) since bus utilization may significantly increase. In this paper, we focus on a security mechanism which keeps the bus utilization as low as possible. Through our experimental results, we show that our security mechanism can achieve high security levels while keeping communication overheads (e.g., bus load and message latency) at reasonable levels.\",\n \"Title: Obstacle-Avoiding Rectilinear Steiner Tree Construction Based on Spanning Graphs\\nYear: 2008\\n\\nAbstract: Given a set of pins and a set of obstacles on a plane, an obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) connects these pins, possibly through some additional points (called the Steiner points), and avoids running through any obstacle to construct a tree with a minimal total wirelength. The OARSMT problem becomes more important than ever for modern nanometer IC designs which need to consider numerous routing obstacles incurred from power networks, prerouted nets, IP blocks, feature patterns for manufacturability improvement, antenna jumpers for reliability enhancement, etc. Consequently, the OARSMT problem has received dramatically increasing attention recently. Nevertheless, considering obstacles significantly increases the problem complexity, and thus, most previous works suffer from either poor quality or expensive running time. Based on the obstacle-avoiding spanning graph, this paper presents an efficient algorithm with some theoretical optimality guarantees for the OARSMT construction. Unlike previous heuristics, our algorithm guarantees to find an optimal OARSMT for any two-pin net and many higher pin nets. Extensive experiments show that our algorithm results in significantly shorter wirelengths than all state-of-the-art works.\",\n \"Title: Timing analysis of process graphs with finite communication buffers\\nYear: 2013\\n\\nAbstract: Real-Time Calculus (RTC) is a modular performance analysis framework for real-time embedded systems. It can be used to compute the worst-case and best-case response times of tasks with general activation patterns and configurations, such as pipelines of tasks that are connected via finite buffers. In this paper, we extend the existing RTC framework to analyze arbitrary graph configurations of tasks and messages, with mixed periodic and event-based activation models and finite buffers between any pair of nodes. Our extension also improves upon several sources of pessimism in the existing analysis. We present an application of the extended RTC to the Loosely Time-Triggered Architecture (LTTA) implementation of synchronous models, commonly used in the development of embedded automotive, avionics and control systems. We show how our method can be used to model scheduling and communication delays in an LTTA mapping, which gives tighter analysis bounds on the output rate and the latency compared to existing techniques. The evaluation on automotive workloads shows that our approach is scalable and outperforms existing techniques in terms of analysis accuracy.\",\n \"Title: Efficient multi-layer obstacle-avoiding rectilinear Steiner tree construction\\nYear: 2007\\n\\nAbstract: Given a set of pins and a set of obstacles on routing layers, a multi-layer obstacle-avoiding rectilinear Steiner minimal tree (ML-OARSMT) connects these pins by rectilinear edges within layers and vias between layers, and avoids running through any obstacle to construct a Steiner tree with a minimal total cost. The ML-OARSMT problem is very important for many VLSI designs with pins being located in multiple routing layers that contain numerous routing obstacles incurred from IP blocks, power networks, prerouted nets, etc. Therefore, it is desired to develop an effective algorithm for the ML-OARSMT problem. However, there is no existing work on the MLOARSMT problem. In this paper, we first formulate the MLOARSMT problem and identify key different properties of the problem from its single-layer counterpart. Based on the multi-layer obstacle-avoiding spanning graph (ML-OASG), we present the first algorithm to solve the ML-OARSMT problem. Our algorithm can guarantee an optimal solution for any 2-pin net and many higher-pin nets. Experiments show that our algorithm results in 33% smaller total costs on average than a construction-by-correction heuristic which is widely used for Steiner-tree construction in the recent literature.\",\n \"Title: Recent Research and Emerging Challenges in Physical Design for Manufacturability/Reliability\\nYear: 2007\\n\\nAbstract: As IC process geometries scale down to the nanometer territory, the industry faces severe challenges of manufacturing limitations. To guarantee yield and reliability, physical design for manufacturability and reliability has played a pivotal role in resolution and thus yield enhancement for the imperfect manufacturing process. In this paper, we introduce major challenges arising from nanometer process technology, survey key existing techniques for handling the challenges, and provide some future research directions in physical design for manufacturability and reliability.\",\n \"Title: AR-Based Positioning for Mobile Devices\\nYear: 2011\\n\\nAbstract: Augmented Reality (AR) that can be considered as a form of location-based services is a technique utilizing position and orientation information and a location database of POIs to enrich video or photographs by adding on graphics or text objects. The AR technique can be used to develop Pedestrian Navigation Systems (PNSs), but high-precision positioning is needed for displaying AR objects at proper places. However, the required level of accuracy is far beyond current commercial positioning solutions, e.g., outdoor GPS and indoor RF systems. In this paper, we propose an AR-based positioning technique for AR users to position their locations. First, by utilizing a coarse positioning system, AR objects can be roughly displayed on the touch screen of a AR device. Then, AR objects can be matched with their images on the display via drag-and-drop operations by users. Thus, both the coordinates of the AR objects in the image and in the real world can be known. Based on the coordinates along with the knowledge of the camera focal length, the location at which the photograph was taken can be known. The location of the camera can be treated as the location of the user. The proposed positioning technique is very helpful in developing high-precision PNSs.\",\n \"Title: A multilayered audiovisual streaming system using the network bandwidth adaptation and the two-phase synchronization\\nYear: 2009\\n\\nAbstract: Synchronous audiovisual streaming and playout are two of the major issues in the multimedia communication network. However, the past corresponding researches of media synchronization mainly focused on the mono-quality and single-layer (nonscalable) audiovisual data. To overcome challenges of ubiquitous multimedia streaming, a scalable audiovisual coder that can provide flexible scalabilities and adaptive streaming control to adapt to complicated network situations are both required. This paper proposes a multilayered audiovisual streaming scheme to deliver layered audiovisual data synchronously, which is called ML-AVSS. Fine-granular scalability (FGS) and bit-sliced arithmetic coding (BSAC) techniques are used to segment video and audio data into one base-layer and multiple enhancement-layer bitstreams. With advantages of audiovisual layer coding, a de-jitter procedure, a conditional retransmission mechanism and a playout synchronization mechanism are designed to transmit hybrid multilayered audiovisual bitstreams in consideration of the result of a network bandwidth adaptation and the distinct decoding time-complexity. Experimental results show that the proposed ML-AVSS is a feasible streaming scheme to overcome challenges of ubiquitous multimedia streaming, e.g., constrained channel bandwidth, quality degradation, unsmooth playout, etc.\",\n \"Title: An Efficient Pre-Assignment Routing Algorithm for Flip-Chip Designs\\nYear: 2012\\n\\nAbstract: The flip-chip package is introduced for modern integrated circuit (IC) designs with higher integration density and larger I/O counts. In this paper, we consider the pre-assignment flip-chip routing problem with predefined connections between driver pads and bump pads. This problem has been shown to be much more difficult than the free-assignment one, but is more popular in real-world designs because the connections between driver pads and bump pads are typically predetermined by IC or packaging designers. Based on the concept of routing sequence exchange, we propose a very efficient approach to guide the global routing by computing the longest common subsequence and the maximum planar subset of chords for pre-assignment flip-chips. We observe that the existing work over-constrains the capacity of a routing tile, which might miss some critical solution space with a better routing solution (e.g., smaller wirelength), and provide a remedy for this insufficiency to identify a better solution in a more complete solution space. We also develop a constant-time routability analyzer to check if a given set of wires can pass through a tile. Experimental results show that our router can achieve a $125\\\\times$ speedup with even better solution quality (same routability with slightly smaller wirelength), compared with a state-of-the-art flip-chip router based on integer linear programming.\",\n \"Title: A multi-core based parallel streaming mechanism for concurrent video-on-demand applications\\nYear: 2009\\n\\nAbstract: In this paper, we design a novel Multi-Core based Parallel Streaming Mechanism for concurrently streaming the scalable extension of H.264/AVC videos, which is called MCPSM. MC-PSM is able to serve lots of heterogeneous users who may utilize distinct terminals through distinct network interfaces to get on-demand videos from an ISP streaming server at meanwhile. With the concept of CPU scheduling- SJF (Shortest- Job-First) and multi-core based parallel programming, multiple streaming tasks can be executed in parallel using a proposed task dispatcher based on network connection speeds, video bit-rate and users' waiting time. Comparing with a normal-threading streaming approach, the average execution time can decrease effectively and CPU resources can be utilized more fully.\",\n \"Title: Multilayer Obstacle-Avoiding Rectilinear Steiner Tree Construction Based on Spanning Graphs\\nYear: 2008\\n\\nAbstract: Given a set of pins and a set of obstacles on routing layers, a multilayer obstacle-avoiding rectilinear Steiner minimal tree (ML-OARSMT) connects these pins by rectilinear edges within layers and vias between layers and avoids running through any obstacle to construct a Steiner tree with a minimal total cost. The ML-OARSMT problem is very important for many very large scale integration designs with pins being located in multiple routing layers that contain numerous routing obstacles incurred from IP blocks, power networks, prerouted nets, etc. As a fundamental problem with extensive practical applications to routing and wirelength/congestion/timing estimations in early design stages, it is desired to develop an effective algorithm for the ML-OARSMT problem to facilitate the design flow. However, there is no existing work on this ML-OARSMT problem. In this paper, we first formulate the ML-OARSMT problem with rectangular obstacles and then identify key different properties of this problem from its single-layer counterpart. Based on the multilayer obstacle-avoiding spanning graph, we present the first algorithm to solve the ML-OARSMT problem. Our algorithm can guarantee an optimal solution for any two-pin net and many multiple-pin nets. Experiments show that our algorithm results in 33% smaller total costs on average than a construction-by-correction heuristic which is widely used for Steiner-tree construction in the recent literature.\",\n \"Title: Mobility Management for Video Streaming on Heterogeneous Networks\\nYear: 2010\\n\\nAbstract: This article discusses how ubiquitous video streaming platform can let people enjoy continuous multimedia services at any time, in any location, and with any computing device. There are several technical challenges to be met in the process of achieving this goal. These challenges entail developing sophisticated session handoff control, session descriptions, communication signaling, and adaptive video streaming, among other factors.\",\n \"Title: An Efficient Wire Routing and Wire Sizing Algorithm for Weight Minimization of Automotive Systems\\nYear: 2014\\n\\nAbstract: As the complexities of automotive systems increase, designing a system is a difficult task that cannot be done manually. In this paper, we propose an algorithm for weight minimization of wires used for connecting electronic devices in a system. The wire routing problem is formulated as a Steiner tree problem with capacity constraints, and the location of a Steiner vertex is selected for adding a splice connecting more than two wires. Besides wire routing, wire sizing is also done to satisfy resistance constraints and minimize the total wiring weight. Experimental results show the effectiveness and efficiency of our algorithm.\",\n \"Title: A Hybrid Spatial-Temporal Fine Granular Scalable Coding for Adaptive QoS Internet Video\\nYear: 2005\\n\\nAbstract: In a ubiquitous multimedia space, a video streaming service is requested to be continuous and uninterrupted even if a client may change her/his client device, network link and preferences at any time and anywhere. Thus, a video coder that can provide more wide range quality-of-service (QoS) and more flexible control is urgently required. This paper presents a hybrid coder structure that integrates spatial-, temporal- and SNR-scalabilities to handle MPEG-4 videos. Using the proposed hybrid coder, different presentation qualities, including spatial-temporal resolution and SNR quality, can be rendered when frames are decoded from the base-layer (BL) and partial enhancement-layer (EL) subbitstreams. Besides, a refined rate-adaptation approach in the MPEG-4 FGS scheme and a buffer control mechanism are also devised to increase the bandwidth utilization and to prevent buffer instability. According to the experiments results, the proposed hybrid coder shows outperformances over classic non-scalable MPEG-2 and MPEG-4 FGS coder in consideration of the flexible QoS for Internet video streaming.\",\n \"Title: A Predictive Video-on-Demand Bandwidth Management Using the Kalman Filter over Heterogeneous Networks\\nYear: 2009\\n\\nAbstract: In order to adapt the quality of an on-demand video stream over a time-varying bandwidth channel, a network-aware bandwidth estimation and rate control scheme are required. This paper proposes a predictive video-on-demand (VoD) bandwidth management and a feedback-based buffer control scheme for streaming fine granular scalability videos over wired/WLAN/3G networks. The predictive VoD bandwidth management includes two parts: bandwidth estimation and rate adaptation. According to the measured information of packet round-trip-time, loss-rate, delay jitter and received bit-rate, an improved Kalman filter is proposed to predict an available bandwidth recursively, and to determine a proper transmission rate in consideration of buffer fullness of a decoder. The optimal parameters of the Kalman filter, e.g. a transition matrix and error covariances, can be initialized, converged and adapted to characteristics of the current network. In our experiments, distinct network traffic models are simulated in comparison with pathChirp and one Republic of China patent. The corresponding estimation results with respect to network information are also exhibited in the real networks.\",\n \"Title: A Multiple Layered Audiovisual Streaming System Using the Two-Phase Synchronization and FGS/BSAC Techniques\\nYear: 2008\\n\\nAbstract: For a ubiquitous multimedia streaming, an adaptive multimedia streaming scheme with multiple layered audiovisual (AV) coding is required over heterogeneous networks. This paper proposes a multiple layered audiovisual streaming scheme denoted ML-AVSS to deliver layered audiovisual data. Fine-granular scalability (FGS) and bit sliced arithmetic coding (BSAC) techniques are used to segment video and audio data into individual base-layer and multiple enhancement-layer bitstreams. With advantages of layered coding, two phases of streaming synchronization, including a human-perceptual based transmission scheme, de-jitter procedure, conditional retransmission and play- out synchronization, are proposed to transmit hybrid multiple layered audiovisual bitstreams. Experiment results show that the proposed ML-AVSS is a feasible streaming scheme to overcome challenges of the ubiquitous multimedia streaming, e.g., constrained available bandwidth, quality degradation, unsmooth playback, etc.\",\n \"Title: A Navigation System for Brain Surgery Using Computer Vision Technology\\nYear: 2008\\n\\nAbstract: In this paper, a surgical navigation system based on stereo-vision has been proposed. With the help of a projector, surface point data of a patient are firstly captured from two cameras by using the stereo-vision technique. Next, these point data is then registered by another surface point data obtained from the patient's pre-stored CT images using Feature-added ICP algorithm. For surgical navigation, a stereo-vision-based tracker is also designed in this system. In this manner, the anatomical information obtained from CT is fused on the images captured by the cameras and the tracker can be mounted to any surgical device for further surgical applications. Compared to conventional image guided surgeries, the proposed system has the advantage of fusing the visual and anatomical information such that it is more accurate and convenient.\",\n \"Title: Efficient obstacle-avoiding rectilinear steiner tree construction\\nYear: 2007\\n\\nAbstract: Given a set of pins and a set of obstacles on a plane, an obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) connects these pins, possibly through some additional points (called Steiner points), and avoids running through any obstacle to construct a tree with a minimal total wirelength. The OARSMT problem becomes more important than ever for modern nanometer IC designs which need to consider numerous routing obstacles incurred from power networks, prerouted nets, IP blocks, feature patterns for manufacturability improvement, antenna jumpers for reliability enhancement, etc. Consequently, the OARSMT problem has received dramatically increasing attention recently. Nevertheless, considering obstacles significantly increases the problem complexity, and thus most previous works suffer from either poor quality or expensive running time. Based on the obstacle-avoiding spanning graph (OASG), this paper presents an efficient algorithm with some theoretical optimality guarantees for the OARSMT construction. Unlike previous heuristics, our algorithm guarantees to find an optimal OARSMT for any 2-pin net and many higher-pin nets. Extensive experiments show that our algorithm results in significantly shorter wirelengths than all state-of-the-art works.\",\n \"Title: Efficient provably good OPC modeling and its applications to interconnect optimization\\nYear: 2010\\n\\nAbstract: Optical Proximity Correction (OPC) is the most popular technique to handle design shape distortions arising from subwavelength lithography. Existing OPC models are typically very computationally expensive and thus not efficient to be incorporated for layout optimization. In this paper, we present an efficient, yet sufficiently accurate OPC cost model which can predict the optimal location of a wire segment for OPC optimization and give an upper bound of the interference amount, guaranteeing that the interference amount is never underestimated. Based on this cost model, we propose an OPC-aware wire perturbation algorithm for post-layout interconnect optimization. We show that the effects of wire perturbation have the concavity or monotonicity property which can dramatically reduce the search space for finding the optimal location of each wire for OPC optimization. Further, we can incrementally update the OPC cost of a wire by recomputing only the affected wires because of the property of superposition of our model. Experimental results show that our algorithm can efficiently obtain much better OPC results than a state-of-the-art OPC-friendly router, based on a leading commercial OPC tool.\",\n \"Title: A Novel 4-D Perceptual Quantization Modeling for H.264 Bit-Rate Control\\nYear: 2007\\n\\nAbstract: Bit-rate control plays a major role In video coding and multimedia streaming. A well-designed bit-rate control mechanism can achieve line visual qualities and avoid network congestion over a time-varying channel. This paper proposes an H.264 bit-rate control using a 4D perceptual quantization modeling (PQrc), including two major encoding modules: the perceptual frame-level bit-allocation using a 1D temporal pattern and the macroblock-level quantizer decision using a 3D rate pattern. The temporal pattern is used to predict frame complexity and determine proper budget bits further. The rate pattern is depicted as a bit-complexity-quantization (B.C.Q.) model, in which a tangent slope of a B.C.Q. curve is a piece of unique information to find a proper quantizer. For newly generated video clips, the B.C.Q. model is updated continuously using a weighted least-square estimation. In comparison with the latest H.264 JM10.2, our experiment results show that the proposed PQrc can: 1) keep stable buffer fullness and 2) improve the SNR quality and control accuracy effectively.\",\n \"Title: Simultaneous OPC- and CMP-aware routing based on accurate closed-form modeling\\nYear: 2013\\n\\nAbstract: As the process technology advances to the nanometer nodes, Optical Proximity Correction (OPC) is the most popular Resolution-Enhancement Technique (RET) in industry for subwavelength lithography, and the inter-level dielectric (ILD) thickness variation caused by the planarization step of the Chemical-Mechanical Polishing (CMP) process also plays a key role for interconnect yield. Considering the OPC and CMP effects simultaneously during the routing stage can significantly alleviate the width and thickness variations (and thus the whole 3D geometry variations) of post-layout RET and CMP operations. In this paper, we first present an efficient, yet sufficiently accurate closed-form formula for printed width computation and dummy-insertion-aware routing cost derivation. The formula provides a cost modeling for post-layout OPC and CMP optimization during routing. Incorporating the OPC and CMP costs, the router can be guided to optimize the effects of layout correction and planarization. Compared with the state-of-the-art OPC-friendly router, QL-MGR (which does not consider CMP), the experimental results show that our approach can achieve respective 19% and 6% reductions in the maximum and average layout distortions. Compared with the state-of-the-art CMP-aware router, TTR (which does not consider OPC), the experimental results show that our approach can achieve respective 19% and 25% reductions in the peak-to-peak thickness and thickness variance. These results indicate that our simultaneous OPC- and CMP-aware router contributes a significant improvement for layout integrity.\",\n \"Title: Security-aware mapping for CAN-based real-time distributed automotive systems\\nYear: 2013\\n\\nAbstract: Cyber-security is a rising issue for automotive electronic systems, and it is critical to system safety and dependability. Current in-vehicles architectures, such as those based on the Controller Area Network (CAN), do not provide direct support for secure communications. When retrofitting these architectures with security mechanisms, a major challenge is to ensure that system safety will not be hindered, given the limited computation and communication resources. We apply Message Authentication Codes (MACs) to protect against masquerade and replay attacks on CAN networks, and propose an optimal Mixed Integer Linear Programming (MILP) formulation for solving the mapping problem from a functional model to the CAN-based platform while meeting both the security and the safety requirements. We also develop an efficient heuristic for the mapping problem under security and safety constraints. To the best of our knowledge, this is the first work to address security and safety in an integrated formulation in the design automation of automotive electronic systems. Experimental results of an industrial case study show the effectiveness of our approach.\",\n \"Title: Security-Aware Modeling and Efficient Mapping for CAN-Based Real-Time Distributed Automotive Systems\\nYear: 2015\\n\\nAbstract: Security has become a critical issue for automotive electronic systems. To protect against attacks, security mechanisms have to be applied, but the overhead of those mechanisms may impede system performance and cause violations of design constraints. To remedy this problem, we proposed an integrated mixed integer linear programming (MILP) formulation that is the first to address both security and safety constraints during system mapping for controller area network (CAN) based systems . However, its signal-based security constraints do not fully reflect real security requirements, and its objective function is to minimize functional path latencies rather than minimize security risk. Furthermore, its MILP-based approach has high computation complexity. In this work, we present a new formulation that defines path-based security constraints and minimizes security risk directly, and propose a new heuristic algorithm to solve the formulation efficiently. Experiments on an industrial example show that our new algorithm achieves comparable solution quality as the MILP-based approach with much better efficiency.\",\n \"Title: Intra-vehicle network routing algorithm for wiring weight and wireless transmit power minimization\\nYear: 2015\\n\\nAbstract: As the complexity of vehicular distributed systems increases rapidly, several hundreds of devices (sensors, actuators, etc.) are being placed in a modern automotive system. With the increase in wiring cables connecting these devices, the weight of a car increases significantly, which degrades the fuel efficiency in driving. In order to reduce the weight of a car, wireless communication has been introduced to replace wiring cables between some devices. However, the extra energy consumption for packet transmissions by wireless devices requires frequent maintenance, e.g., recharging of batteries. In this paper, we propose an intra-vehicle network routing algorithm to simultaneously minimize the wiring weight and the transmit power for wireless communication. Experimental results show that the proposed method can effectively minimize the wiring weight and the transmit power for wireless communication.\",\n \"Title: Security-aware mapping for TDMA-based real-time distributed systems\\nYear: 2014\\n\\nAbstract: Cyber-security has become a critical issue for real-time distributed embedded systems in domains such as automotive, avionics, and industrial automation. However, in many of such systems, tight resource constraints and strict timing requirements make it difficult or even impossible to add security mechanisms after the initial design stages. To produce secure and safe systems with desired performance, security must be considered together with other objectives at the system level and from the beginning of the design. In this paper, we focus on security-aware design for Time Division Multiple Access (TDMA) based real-time distributed systems. The TDMA-based protocol we consider is an abstraction of many time-triggered protocols that are being adopted in various safety-critical systems for their more predictable timing behavior, such as FlexRay, Time-Triggered Protocol, and Time-Triggered Ethernet. To protect against attacks on TDMA-based real-time distributed systems, we apply a message authentication mechanism with time-delayed release of keys, which provides a good balance between security and computational overhead but needs sophisticated network scheduling to ensure that the increased latencies due to delayed key releases will not violate timing requirements. We propose formulations and an algorithm to optimize the task allocation, priority assignment, network scheduling, and key-release interval length during the mapping process, while meeting both security and timing requirements. Experimental results of an automotive case study and a synthetic example show the effectiveness and efficiency of our approach.\",\n \"Title: Buffered clock tree synthesis considering self-heating effects\\nYear: 2014\\n\\nAbstract: A clock tree typically consumes substantial dynamic power, and thus the considerable heat generated by itself can cause serious clock-skew variations. In this paper, we propose a self-heating-aware buffered clock tree synthesis flow. A mixed integer linear programming (MILP) formulation is proposed to simultaneously model heat spreading, place buffers, and determine a temperature-aware clock tree topology. The formulation is then transformed into a succession of low-complexity feasibility problems to further reduce the runtime. In addition, a fast superposition approach is proposed to incrementally update thermal profiles to reduce simulation time. Experimental results show that our synthesis flow can achieve averagely 50.57% worst-case clock skew reduction, compared with the original symmetrical clock tree.\",\n \"Title: Efficient Wire Routing and Wire Sizing for Weight Minimization of Automotive Systems\\nYear: 2015\\n\\nAbstract: As the complexities of automotive systems increase, designing a system is a difficult task that cannot be done manually. In this paper, we focus on wire routing and wire sizing for weight minimization to deal with more and more connections between devices in automotive systems. The wire routing problem is formulated as a minimal Steiner tree problem with capacity constraints, and the location of a Steiner vertex is selected to add a splice which is used to connect more than two wires. We modify the KMB algorithm [12] to efficiently construct Steiner trees and propose an Integer Linear Programming (ILP) formulation to relocate Steiner vertices and satisfy capacity constraints. The ILP formulation is relaxed to a Linear Programming (LP) formulation which has the same optimal objective and can be solved more efficiently. Besides wire routing, wire sizing is also performed to satisfy resistance constraints and minimize the total wiring weight. To the best of our knowledge, this is the first work in the literature to formulate the automotive routing problem as a minimal Steiner tree problem with capacity constraints and perform wire routing and wire sizing for weight minimization. An industrial case study shows the effectiveness and efficiency of our algorithm which provides an efficient, flexible, and scalable approach for the design optimization of automotive systems.\",\n \"Title: The dynamic influence of emotions on game-based creativity: An integrated analysis of emotional valence, activation strength, and regulation focus.\\nYear: 2016\\n\\nAbstract: Emotion has been identified as an important predictor of creativity, but little attention has been put on investigating how emotion, especially that considers regulation focus, may dynamically influence male and female students' creativity in game-based situations. To explore the dynamic relationship between various types of emotions and creativity during game playing, 266 college students were included and the Creativity Game-based Evaluation System (CGES) was developed in this study. Four types of emotions integrating perspectives of valence (positive vs. negative), activation (high vs. low), and regulatory focus (prevention vs. promotion) were investigated in this study: the positive-low activation-prevention emotion (P-L-Pre) (calm and relaxed), the positive-high activation-promotion emotion (P-H-Pro) (happy and elated), the negative-high activation-prevention emotion (N-H-Pre) (nervous and anxious), and the negative-high activation-promotion emotion (N-H-Pro) (frustrated and angry). The results revealed that, although there was a slight gender difference in game-based creativity, the prediction patterns of emotions in game-based creativity were very similar among participants with different genders. Specifically, emotions during game playing can better predict creativity than those of the baseline; moreover, the P-H-Pro emotion can facilitate performance on creativity, whereas the N-H-Pro emotion can decrease creativity performance. Thus, providing appropriate challenges to induce highly-activated and promotion-focused positive emotions are critical for the success of games designed to improve creativity.\",\n \"Title: Security-Aware Design Methodology and Optimization for Automotive Systems\\nYear: 2015\\n\\nAbstract: In this article, we address both security and safety requirements and solve security-aware design problems for the controller area network (CAN) protocol and time division multiple access (TDMA)-based protocols. To provide insights and guidelines for other similar security problems with limited resources and strict timing constraints, we propose a general security-aware design methodology to address security with other design constraints in a holistic framework and optimize design objectives. The security-aware design methodology is further applied to solve a security-aware design problem for vehicle-to-vehicle (V2V) communications with dedicated short-range communication (DSRC) technology. Experimental results demonstrate the effectiveness of our approaches in system design without violating design constraints and indicate that it is necessary to consider security together with other metrics during design stages.\",\n \"Title: Invited - Cooperation or competition?: coexistence of safety and security in next-generation ethernet-based automotive networks\\nYear: 2016\\n\\nAbstract: Safety is traditionally the most relevant property for automotive systems, and it is further enhanced by Advanced Driver Assistance Systems (ADAS) in modern automotive systems. To support ADAS and other advanced autonomous functions, automotive electronic systems become more distributed and connected than ever, with in-vehicle architecture or Vehicle-to-X (V2X) communication. These connections create a variety of interfaces which become breeding grounds for security attacks. Accordingly, security becomes a rising issue for automotive systems. In this paper, we address safety and security together, especially their interactions, in Ethernet-based automotive networks which are believed to be the next-generation automotive networks since they are able to provide high bandwidths, certain timing guarantees, and well-developed technologies. We discuss the interactions between safety and security in three problems: secret key management, frame replication and elimination, and Virtual Local Area Network (VLAN) segmentation. We demonstrate that safety and security can work together, but sometimes there is a trade-off between them. This indicates that safety cannot stand alone without considering security, and network security is a necessary component of system security. Towards safer and securer automotive systems, safety and security should be considered together during design stages of automotive systems.\",\n \"Title: Next Generation Automotive Architecture Modeling and Exploration for Autonomous Driving\\nYear: 2016\\n\\nAbstract: To support emerging applications in autonomous and semi-autonomous driving, next-generation automotive systems will be equipped with an increasing number of heterogeneous components (sensors, actuators and computation units connected through various buses), and have to process a high volume of data to percept the environment accurately and efficiently. Challenges for such systems include system integration, prediction, verification and validation. In this work, we propose an architecture modeling and exploration framework for evaluating various software and hardware architecture options. The framework will facilitate system integration and optimization, and enable validation of various design metrics such as timing, reliability, security and performance.\",\n \"Title: CONVINCE: a cross-layer modeling, exploration and validation framework for next-generation connected vehicles.\\nYear: 2016\\n\\nAbstract: Next-generation autonomous and semi-autonomous vehicles will not only precept the environment with their own sensors, but also communicate with other vehicles and surrounding infrastructures for vehicle safety and transportation efficiency. The design, analysis and validation of various vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) applications involve multiple layers, from V2V/V2I communication networks down to software and hardware of individual vehicles, and concern with stringent requirements on multiple metrics such as timing, security, reliability and fault tolerance. To cope with these challenges, we have been developing CONVINCE, a cross-layer modeling, exploration and validation framework for connected vehicles. The framework includes mathematical models, synthesis and validation algorithms, and a heterogeneous simulator for inter-vehicle communications and intra-vehicle software and hardware in a holistic environment. It explores various design options with respect to constraints and objectives on system safety, security, reliability, cost, etc. A V2V application is used in the case study to demonstrate the effectiveness of the proposed framework.\",\n \"Title: Platform-Based Plug and Play of Automotive Safety Features: Challenges and Directions (Invited Paper).\\nYear: 2016\\n\\nAbstract: Optional software-based features are increasingly becoming an important cost driver in automotive systems. These include features pertaining to active safety, infotainment, etc. Currently, these optional features are integrated into the vehicles at the factory during assembly. This severely restricts the flexibility of the customer to select and use features on-demand and therefore, the customer will either have to be satisfied with an available set of feature options or pre-order a car with the required features from the manufacturer resulting in considerable delay. In order to increase flexibility and reduce the delay, it is necessary to provide the option to configure the vehicle on-demand at the dealership or remotely. In this paper, we present our vision and challenges involved in developing a platform infrastructure that allows on-demand deployment of automotive safety features and ensures their correct execution.\",\n \"Title: Design space exploration for deterministic ethernet-based architecture of automotive systems\\nYear: 2016\\n\\nAbstract: Time Triggered Ethernet (TTE) is a time-triggered network technology with large bandwidth and services for deterministic, safety-relevant communication. Hence, it has gained increasing attention from domains such as aerospace, automotive and industrial applications. In this work, we aim to solve the problem of task mapping and communication scheduling in automotive design. The system model is a dataflow task communication model mapped to a target architecture based on TIE. The design variables are the mapping of tasks onto the end systems in the architecture and the scheduling of all frames. The constraints include the schedulability of tasks and signals, as well as the latency constraints of the critical paths as specified by the designer. It can be shown that the problem is NP· hard. Therefore, we develop a heuristic to solve this problem. The heuristic contains four steps and all of them (except scheduling) are formulated using Integer Linear Programming (ILP). We present experimental results on an industrial benchmark and two synthetic benchmarks which show the efficiency and scalability of our approach.\",\n \"Title: An Amanat-Based Multi-party Certification Protocol for Outsourced Software in Automotive Systems\\nYear: 2016\\n\\nAbstract: As autonomous features advance, it is believed that most behaviors, including safety-critical functions, of future automotive systems will be defined by software. Due to the safety-critical nature, correctness and quality of automotive software draw more and more concerns, and software certification should integrate verification, simulation, and testing results in systematic and rigorous ways to prove the fulfillment of governments' regulations, reduce system designers' liability, and enhance customers' confidence. Expecting that software certification will become a necessary step in future automotive design, we resolve a conflict between certification issuers and software suppliers and developers in this paper. Based on the Amanat protocol [6], we address its challenges in the automotive domain and propose a protocol which guarantees authenticity to certification issuers and confidentiality to software suppliers and developers. Authenticity means that only authenticated results from compilers and analysis tools (verification, simulation, and/or testing) are considered by the certification issuers in the certification process, and confidentiality means that sensitive source codes of the software suppliers and developers are not released to certification issuers. The proposed protocol is an important step towards the realization of practical automotive software certification.\",\n \"Title: Delay-Bounded Intravehicle Network Routing Algorithm for Minimization of Wiring Weight and Wireless Transmit Power.\\nYear: 2017\\n\\nAbstract: As the complexity of vehicular distributed systems increases rapidly, several hundreds of devices are being placed in a modern automotive system. With the increase in wiring cables connecting these devices, the weight of a vehicle increases significantly and degrades the fuel efficiency during driving. In order to reduce the wiring weight, wireless communication has been introduced to replace wiring cables between some devices. However, the extra energy consumption and the transmission delay due to wireless communication need to be considered because they may result in frequent maintenance (e.g., recharging of batteries) and deadline violation, respectively. In this paper, we propose an intravehicle network routing algorithm to simultaneously minimize the wiring weight and the wireless transmit power while considering the transmission delay in automotive systems. Experimental results show that the proposed method can effectively minimize the wiring weight and the wireless transmit power and satisfy other design constraints.\",\n \"Title: Accurate High-level Modeling and Automated Hardware/Software Co-design for Effective SoC Design Space Exploration.\\nYear: 2017\\n\\nAbstract: A desirable feature of a development tool for SoC design is that, given the important applications in the domain to be targeted by the SoC, a powerful hardware-software partitioning engine is available to determine which function(s) shall be mapped to hardware. However, to provide high-quality partitioning, this engine must be able to consider a rich design space of possible alternate hardware and software implementations for each program region candidate for hardware acceleration, in turn making the task of finding the optimal mapping very difficult given the number of design points to consider and the need for accurate modeling of latency, power and area. In this work we propose a novel framework to enable hardware acceleration of performance-critical parts of an application, by addressing the problem of hardware/software partitioning under power and area constraints to minimize the overall program latency. Our flow is based on the LLVM compiler, and focuses on building a scalable compile-time partitioning algorithm while considering large sets of alternative hardware and software implementations for a particular region. To this end we develop a hybrid approach based on mixing semi-random selection of hardware design points and an Integer Linear Programming formulation of the mapping decision, along with iterative refinements of the solution. Experimental results demonstrate the capability of our approach to consider complex designs and yet output near-optimal partitioning decision. Our package is named RIP (Randomized ILP-based Partitioning), and is open source to benefit the research community.\",\n \"Title: Delay-Aware Design, Analysis and Verification of Intelligent Intersection Management\\nYear: 2017\\n\\nAbstract: With the rapid advancement of autonomous driving and vehicular communication technology, intelligent intersection management has shown great promise in improving transportation efficiency. In a typical intelligent intersection, an intersection manager communicates with autonomous vehicles wirelessly and schedules their crossing of the intersection. Previous system designs, however, do not address the possible communication delays due to network congestion or security attacks, and could lead to unsafe or deadlocked systems. In this work, we propose a delay- tolerant protocol for intelligent intersection management, and develop a modeling, simulation and verification framework for analyzing the protocol's safety, liveness and performance. Experiments demonstrate the advantages of our proposed protocol over traditional traffic light control, and more importantly, demonstrate the importance and effectiveness of using this framework to address timing (delay) in vehicular network applications. This work is the first step towards a comprehensive delay-aware design and verification framework for practical vehicular network applications.\",\n \"Title: Principles for Systematic Development of an Assurance Case Template from ISO 26262\\nYear: 2017\\n\\nAbstract: A failure in a critical system can cause death, injury, financial loss, and environmental damage. To develop safe and trustworthy systems, we need to plan the development and assessment of system functionality in advance. Assurance Cases are a generalization of Safety Cases, and are gaining momentum as a preferred way of demonstrating assurance of critical properties in complex software-intensive systems. To cope with the lack of standardized assurance structures, and to encourage safety assessment prior to development, we previously proposed the use of an assurance case template. The principles presented here can be used to build an assurance case template that complies with the functional safety standard, ISO 26262 in a cost-effective way. In the future, such principles may lead to semi-automated development of these templates.\",\n \"Title: Reliable Intersection Control in Non-cooperative Environments.\\nYear: 2018\\n\\nAbstract: We propose a reliable intersection control mechanism for strategic autonomous and connected vehicles (agents) in non-cooperative environments. Each agent has access to his/her earliest possible and desired passing times, and reports a passing time to the intersection manager, who allocates the intersection temporally to the agents in a First-Come-First-Serve basis. However, the agents might have conflicting interests and can take actions strategically. To this end, we analyze the strategic behaviors of the agents and formulate Nash equilibria for all possible scenarios. Furthermore, among all Nash equilibria we identify a socially optimal equilibrium that leads to a fair intersection allocation, and correspondingly we describe a strategy-proof intersection mechanism, which achieves reliable intersection control such that the strategic agents do not have any incentive to misreport their passing times strategically.\",\n \"Title: Distributed Conflict Resolution for Connected Autonomous Vehicles.\\nYear: 2018\\n\\nAbstract: This paper proposes a novel communication-enabled distributed conflict resolution mechanism in order for a group of connected autonomous vehicles to navigate safely and efficiently in intersections without any traffic manager. The conflict resolution strategy for individual vehicle is decoupled temporally. In a decision maker, the vehicle computes the desired time slots to pass the conflict zones ...\",\n \"Title: Runtime monitoring for safety of intelligent vehicles\\nYear: 2018\\n\\nAbstract: Advanced driver-assistance systems (ADAS), autonomous driving, and connectivity have enabled a range of new features, but also made automotive design more complex than ever. Formal verification can be applied to establish functional correctness, but its scalability is limited due to the sheer complexity of a modern automotive system. To manage high complexity and limited development resources, one alternative is to apply runtime monitoring techniques to detect when the system transitions into an unsafe state (i.e., one where it violates a critical safety requirement). In this paper, we report on our experience integrating runtime monitoring into a development workflow and present practical design considerations on languages and tools from an industrial perspective. Using signal temporal logic (STL) [12] and the Breach [6] monitoring tool, we perform a case study showing how monitoring can be used to detect undesirable interactions between two ADAS features called Cooperative Pile-up Mitigation System (CPMS) and False-Start Prevention System (FPS). This is an initial step to utilize runtime monitoring to achieve high assurance in the design of intelligent vehicles.\",\n \"Title: Threat Detection for Collaborative Adaptive Cruise Control in Connected Cars.\\nYear: 2018\\n\\nAbstract: We study collaborative adaptive cruise control as a representative application for safety services provided by autonomous cars. We provide a detailed analysis of attacks that can be conducted by a motivated attacker targeting the collaborative adaptive cruise control algorithm, by influencing the acceleration reported by another car, or the local LIDAR and RADAR sensors. The attacks have a strong impact on passenger comfort, efficiency and safety, with two of such attacks being able to cause crashes. We also present two detection methods rooted in physical-based constraints and machine learning algorithms. We show the effectiveness of these solutions through simulations and discuss their limitations.\",\n \"Title: Distributed file allocation using matching game in mobile fog-caching service network\\nYear: 2018\\n\\nAbstract: The fog-caching enabled radio access network has been identified as an effective solution to reduce content down-loading latency of mobile users (MUs). The quality of service (QoS) can be dramatically enhanced by caching popular files into the storages of femto-cell access points (FAPs) adjacent to MUs. However, file allocation is challenging when the mobility of users is considered. In this scenario, the serving users of each FAP are not fixed, and they vary from time to time. In order to address this, we design distributed algorithms, using two separate matching games, with the aim to minimize the system file downloading latency. To be specific, we first allocate files to each FAP and then associate an MU with a proper FAP, considering the mobility of users. At last, numerical results are presented to demonstrate the effectiveness of the proposed algorithms. It is verified that the proposed algorithms outperform the benchmark in terms of achieving a lower transmission delay.\",\n \"Title: Bandwidth Optimal Data/Service Delivery for Connected Vehicles via Edges\\nYear: 2018\\n\\nAbstract: The paradigm of connected vehicles is fast gaining lot of attraction in the automotive industry. Recently, a lot of technological innovation has been pushed through to realize this paradigm using vehicle to cloud (V2C), infrastructure (V2I) and vehicle (V2V) communications. This has also opened the doors for efficient delivery of data/service to the vehicles via edge devices that are closer to the vehicles. In this work, we propose an optimization framework that can be used to deliver data/service to the connected vehicles such that a bandwidth cost objective is optimized. For the first time, we also integrate a vehicle flow model in the optimization framework to model the traffic flow in the coverage area of the edges. Using the optimization framework, we study the variation of the optimal bandwidth cost for varying problem sizes and vehicle flow model parameter values for both data and service delivery.\",\n \"Title: Property-Driven Runtime Resolution Of Feature Interactions\\nYear: 2018\\n\\nAbstract: The feature interaction problem occurs when two or more features interact and possibly conflict with each other in unexpected ways, resulting in undesirable system behaviors. Common approaches to resolving feature interactions are based on priorities, which are ineffective in scenarios where the set of features may evolve past the design phase, and where desirability of features may change dynamically depending on the state of the environment. This paper introduces a property-driven approach to feature-interaction resolution, where a desired system property is leveraged to determine which feature action should be enabled at a given context. Compared to existing approaches, our approach is capable of (1) providing resolutions even if the system evolves with new or modified features, and (2) handling complex resolution scenarios where the preference of one feature over the others may change dynamically. We demonstrate the effectiveness of our approach through a case study involving resolution of safety-critical features in an intelligent vehicle.\",\n \"Title: Network and system level security in connected vehicle applications\\nYear: 2018\\n\\nAbstract: Connected vehicle applications such as autonomous intersections and intelligent traffic signals have shown great promises in improving transportation safety and efficiency. However, security is a major concern in these systems, as vehicles and surrounding infrastructures communicate through ad-hoc networks. In this paper, we will first review security vulnerabilities in connected vehicle applications. We will then introduce and discuss some of the defense mechanisms at network and system levels, including (1) the Security Credential Management System (SCMS) proposed by the United States Department of Transportation, (2) an intrusion detection system (IDS) that we are developing and its application on collaborative adaptive cruise control, and (3) a partial consensus mechanism and its application on lane merging. These mechanisms can assist to improve the security of connected vehicle applications.\",\n \"Title: Quotient for Assume-Guarantee Contracts.\\nYear: 2018\\n\\nAbstract: We introduce a novel notion of quotient set for a pair of contracts and the operation of quotient for assume-guarantee contracts. The quotient set and its related operation can be used in any compositional methodology where design requirements are mapped into a set of components in a library. In particular, they can be used for the so called missing component problem, where the given components are not capable of discharging the obligations of the requirements. In this case, the quotient operation identifies the contract for a component that, if added to the original set, makes the resulting system fulfill the requirements.\",\n \"Title: Platform-Independent QoS Parameters and Primitive APIs for Automotive Software\\nYear: 2018\\n\\nAbstract: Modern ITS (Intelligent Transportation System) applications are becoming increasingly sophisticated and diverse, following the growing trends of connectivity and autonomous driving. For example, a vehicle can be equipped with advanced sensors (e.g., LIDAR, camera or radar) to perform complex driving maneuvers by itself and/or communicate with other vehicles or road-side infrastructures to assist drivers in safer driving. Since the operation of an automotive application is closely tied to the underlying platform characteristics, it requires significant integration effort when the application needs to operate on a wide range of platforms such as other vehicle types or road-side infrastructures. To reduce such effort, we propose a method to implement automotive applications in a platform-independent way. Our approach is to define the automotive domain-specific QoS (Quality of Service) parameters that allow an application to specify the expected quality of sensor input or actuator output independent of a particular platform for safe operation. The application interacts with a platform through several primitive APIs to inform QoS requirements, to read/write sensors/actuators values according to the specified QoS, and to handle exceptions upon any QoS violation. We implement a multi-mode ACC (Adaptive Cruise Control) application on a RC-car platform to demonstrate how an automotive application can be implemented based on the proposed QoS parameters and primitives.\",\n \"Title: Poster: Formal QoS Compatibility Verification for Components on Time-Sensitive Networking\\nYear: 2018\\n\\nAbstract: System integration has became more challenging than ever. In this poster, we propose to use a formal approach to verify the Quality of Service (QoS) compatibility of components connected by the Time-Sensitive Networking (TSN) [6]. We demonstrate that the formal approach, if realized, is applicable to various stages including specification definition of components to be developed, integration with existing components, runtime monitoring with adaptive components, and maintenance of components.\",\n \"Title: Information-Driven Autonomous Intersection Control via Incentive Compatible Mechanisms\\nYear: 2019\\n\\nAbstract: We propose a new information-driven intersection control to enhance the quality of transportation by using communication between vehicles and roadside units. The state-of-the-art solutions for intersection control only have access to the sensor data that is collected by vehicles or roadside units. However, congestion at intersections can have different impact on different drivers, and yet such an impact cannot be measured by sensors. An effective intersection control can consider such driver-exclusive differences based on the information reported by the drivers, which can substantially enhance the quality of transportation. However, such information is driver-exclusive, i.e., not verifiable easily, and therefore prone to be misreported strategically. We propose strategy-proof intersection control addressing such issues via a payment-based incentive-compatible mechanism. Particularly, vehicles at close proximity of the intersection report their driver-exclusive utility functions that they want to maximize (not necessarily truthfully), while the roadside unit seeks to maximize the sum of those utilities, i.e., social welfare, by scheduling intersection usage and charging each vehicle an amount of time-tokens corresponding to their impact on other drivers. This approach, based on the Vickrey-Clarke-Groove mechanism, \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">guarantees</italic>\\n truthful utility reporting by the vehicles and, correspondingly, \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">maximizes</italic>\\n the social welfare. The proposed scheme is universal such that it can be implemented based on various utility functions or intersection control constraints. We also provide a practical implementation to analyze the performance via numerical simulations.\",\n \"Title: Timing and security analysis of VANET-based intelligent transportation systems: (Invited paper).\\nYear: 2017\\n\\nAbstract: With the fast development of autonomous driving and vehicular communication technologies, intelligent transportation systems that are based on VANET (Vehicular Ad-Hoc Network) have shown great promise. For instance, through V2V (Vehicle-to-Vehicle) and V2I (Vehicle-to-Infrastructure) communication, intelligent intersections allow more fine-grained control of vehicle crossings and significantly enhance traffic efficiency. However, the performance and safety of these VANET-based systems could be seriously impaired by communication delays and packet losses, which may be caused by network congestion or by malicious attacks that target communication timing behavior. In this paper, we quantitatively model and analyze some of the timing and security issues in transportation networks with VANET-based intelligent intersections. In particular, we demonstrate how communication delays may affect the performance and safety of a single intersection and of multiple interconnected intersections, and present our delay-tolerant intersection management protocols. We also discuss the issues of such protocols when the vehicles are non-cooperative and how they may be addressed with game theory.\",\n \"Title: Improving Efficiency Of Autonomous Vehicles By V2v Communication\\nYear: 2018\\n\\nAbstract: Autonomous vehicles are widely regarded as a promising technology to improve the safety of transportation systems. However, the efficiency of vehicles may be compromised to ensure safety when there are large uncertainties in perception and prediction of the behaviors of other road participants due to limitations in sensors. To remedy this problem, vehicle to vehicle (V2V) communication is applied to improve efficiency of autonomous vehicles during interactions with other vehicles. By requiring the vehicles to communicate their intentions with one another, the efficiency of the vehicles can be improved in terms of smaller variations in their speed profiles and smaller delay as demonstrated in the simulations.\",\n \"Title: From Electronic Design Automation to Automotive Design Automation.\\nYear: 2019\\n\\nAbstract: Advanced driver assistance systems (ADAS), autonomous functions, and connected applications bring a revolution to automotive systems, but they also make automotive design, especially software and electronics, more complex than ever. The complexity introduces significant challenges to automotive industry, and thus design automation, model-based design, and platform-based design can assist system designers to verify design correctness, improve design quality, accelerate design development, reduce design cost, and prevent redesign or recall. Sharing similar concepts with electronic design automation, automotive design automation can be categorized into three core parts: modeling, design (including synthesis and optimization), and analysis (including verification, simulation, and testing).\\n\\nIn this talk, we first go through some examples of modeling, design, and analysis in both of electronic design automation and automotive design automation. Next, we present two routing problems, one applicable to circuit physical design and automotive harness design and the other one applicable to microfluidic biochip design and intersection management, and discuss their similarities and differences. Then, we bring out four design-time problems in the automotive domain: (1) placement which allocates tasks onto automotive systems, edges, and the cloud, (2) verification which checks the compatibility of automotive sub-systems, (3) software integrity which aims to comply with an automotive functional safety standard, ISO 26262, and (4) security-aware design and analysis which provide decisions at the early stages in the V-model.\\n\\nBesides the existing solutions and research challenges of these problems, how the techniques in electronic design automation can facilitate addressing these problems is also covered. We believe that the techniques can not only contribute solutions to integrated circuit design and automotive design but also give insights to the design of embedded systems, cyber-physical systems, and other complex systems.\",\n \"Title: Vehicle Sequence Reordering With Cooperative Adaptive Cruise Control\\nYear: 2019\\n\\nAbstract: With Cooperative Adaptive Cruise Control (CACC) systems, vehicles are allowed to communicate and cooperate with each other to form platoons and improve the traffic throughput, traffic performance, and energy efficiency. In this paper, we take into account the braking factors of different vehicles so that there is a desired platoon sequence which minimizes the platoon length. We formulate the vehicle sequence reordering problem and propose an algorithm to reorder vehicles to their desired platoon sequence.\",\n \"Title: A Game Theoretical Error-Correction Framework for Secure Traffic-Sign Classification.\\nYear: 2019\\n\\nAbstract: We introduce a game theoretical error-correction framework to design classification algorithms that are reliable even in adversarial environments, with a specific focus on traffic-sign classification. Machine learning algorithms possess inherent vulnerabilities against maliciously crafted inputs especially at high dimensional input spaces. We seek to achieve reliable and timely performance in classification by redesigning the input space physically to significantly lower dimensions. Traffic-sign classification is an important use-case enabling the redesign of the inputs since traffic-signs have already been designed for their easy recognition by human drivers. We encode the original input samples to, e.g., strings of bits, through error-correction methods that can provide certain distance guarantees in-between any two different encoded inputs. And we model the interaction between the defense and the adversary as a game. Then, we analyze the underlying game using the concept of hierarchical equilibrium, where the defense strategies are designed by taking into account the best possible attack against them. At large scale, for computational simplicity, we provide an approximate solution, where we transform the problem into an efficient linear program with substantially small size compared to the original size of the entire input space. Finally, we examine the performance of the proposed scheme over different traffic-sign classification scenarios.\",\n \"Title: Human-Robot Cooperation for Autonomous Vehicles and Human Drivers: Challenges and Solutions\\nYear: 2021\\n\\nAbstract: Connected and automated vehicles (CAVs) are becoming increasingly feasible, and these vehicles are expected to enhance road safety, traffic throughput, energy efficiency, and human comfort, especially at road intersections and for lane changing, merging, and unprotected turning maneuvers. However, there is likely to be a long transition period before human-driven vehicles are completely replaced b...\",\n \"Title: Efficient Mandatory Lane Changing of Connected and Autonomous Vehicles\\nYear: 2021\\n\\nAbstract: In a mandatory lane-changing scenario, vehicles need to move to their target lanes before the end of a road segment. Mandatory lane changing usually happens near a highway ramp, and it is one major source of traffic congestion and delay. The advance of connected and autonomous vehicles supports to solve the problem in a centralized and precise way. We formulate a mandatory lane-changing problem and propose a Mixed-Integer Linear Programming (MILP) approach to find an optimal solution. We then propose an MILP-based incremental-window algorithm to solve the problem efficiently. Experimental results show that the MILP-based incremental-window algorithm can take much less computation time and achieve almost the same solution quality, compared with the original MILP approach. The advantage of efficiency yet sufficient effectiveness matches the need of high-level control (decision of passing order) well.\",\n \"Title: Compatibility Checking for Autonomous Lane-Changing Assistance Systems\\nYear: 2022\\n\\nAbstract: Different types of lane-changing assistance systems are usually developed separately by different automotive makers or suppliers. A lane-changing model can meet its own requirements, but it may be incompatible with another lane-changing model. In this paper, we verify if two lane-changing models are compatible so that the two corresponding vehicles on different lanes can exchange their lanes successfully. We propose a methodology and an algorithm to perform the verification on the combinations of four lane-changing models. Experimental results demonstrate the compatibility (or incompatibility) between the models. The verification results can be utilized during runtime to prevent incompatible vehicles from entering a lane-changing road segment. To the best of our knowledge, this is the first work considering the compatibility issue for lane-changing models.\",\n \"Title: Deadlock Analysis and Prevention for Intersection Management Based on Colored Timed Petri Nets\\nYear: 2022\\n\\nAbstract: We propose a Colored Timed Petri Net (CTPN) based model for intersection management. With the expressiveness of the CTPN-based model, we can consider timing, vehicle-specific information, and different types of vehicles. We then design deadlock-free policies and guarantee deadlock-freeness for intersection management. To the best of our knowledge, this is the first work on CTPN-based deadlock analysis and prevention for intersection management.\",\n \"Title: Deadlock Resolution for Intelligent Intersection Management with Changeable Trajectories\\nYear: 2022\\n\\nAbstract: Intelligent intersection management aims to schedule vehicles so that vehicles can pass through an intersection efficiently and safely. However, inaccurate control, imperfect communication, and malicious information or behavior lead to robustness issues of intelligent intersection management. In this work, we focus on improving robustness against deadlocks by changing the trajectories of vehicles. To guarantee the resolvability of deadlocks, we limit the number of vehicles in an intersection to be smaller than or equal to an intersection-specific value called the maximal deadlock-free load. We develop an algorithm to compute the maximal deadlock-free load. We further reduce the computation time by computing the loads which are pessimistic (smaller) but still deadlock-free. Since the maximal deadlock-free load only depends on the given intersection, it can be integrated with different scheduling algorithms. Experimental results demonstrate that, by changing the trajectories of vehicles and limiting the number of vehicles under maximal deadlock-free loads, our approach can guarantee deadlock-freeness and maintain good traffic efficiency.\",\n \"Title: Deep-Learning-Based Anomaly Detection for Lane-Changing Decisions\\nYear: 2022\\n\\nAbstract: Vehicles can utilize their sensors or receive messages from other vehicles to acquire information about the surrounding environments. However, the information may be inaccurate, faulty, or maliciously compromised due to sensor failures, communication faults, or security attacks. The goal of this work is to detect if a lane-changing decision and the sensed or received information are anomalous. We develop three anomaly detection approaches based on deep learning: a classifier approach, a predictor approach, and a hybrid approach combining the classifier and the predictor. All of them do not need anomalous data nor lateral features so that they can generally consider lane-changing decisions before the vehicles start moving along the lateral axis. They achieve at least 82% and up to 93% F-1 scores against anomaly on data from Simulation of Urban MObility (SUMO) [1] and HighD [2]. We also examine system properties and verify that the detected anomaly includes more dangerous scenarios.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":63,"string":"63"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":246,"string":"246"}}},{"rowIdx":247,"cells":{"question_id":{"kind":"string","value":"Davy Preuveneers"},"question":{"kind":"string","value":"Generate an abstract for the title \"QoC2 Breaker: intelligent software circuit breakers for fault-tolerant distributed context-aware applications.\" using the following items: reliability, context-aware applications, fault-tolerant behavior, Design for Failure, QoC Breaker framework."},"answer":{"kind":"string","value":"Reliability is a key concern when distributed context-aware applications assist end-users in intelligent environments. As these adaptive applications are never deployed in isolation, delivering failsafe behavior is a non-trivial challenge. Indeed, they usually operate well in the cool comfort of a lab environment, but may not behave as expected in the real world due to unforeseen circumstances. Furthermore, intelligent environments continuously evolve as end-users install and interconnect new sensors, actuators or other appliances. These observations make it challenging for software engineers to design, develop and deploy context-aware distributed applications that guarantee fault-tolerant behavior under all possible situations. In this work, we advocate a ‘Design for Failure’ approach to build applications that are expected to handle faults gracefully. We use enhanced software circuit breakers for distributed context-aware applications to deliver fault-tolerant intelligent environments. Our QoC \\(^{2}\\) Breaker framework specializes circuit breakers with notions of Quality of Context to offer context-aware applications a greater stability and resilience against different types of faults. The evaluation of our framework on a prototypical case study shows that it can mitigate circumstances where isolated or transient errors can cascade into catastrophic failures throughout the whole intelligent environment, and this with a limited performance overhead."},"correct_answer":{"kind":"string","value":"Reliability is a key concern when distributed context-aware applications assist end-users in intelligent environments. As these adaptive applications are never deployed in isolation, delivering failsafe behavior is a non-trivial challenge. Indeed, they usually operate well in the cool comfort of a lab environment, but may not behave as expected in the real world due to unforeseen circumstances. Furthermore, intelligent environments continuously evolve as end-users install and interconnect new sensors, actuators or other appliances. These observations make it challenging for software engineers to design, develop and deploy context-aware distributed applications that guarantee fault-tolerant behavior under all possible situations. In this work, we advocate a ‘Design for Failure’ approach to build applications that are expected to handle faults gracefully. We use enhanced software circuit breakers for distributed context-aware applications to deliver fault-tolerant intelligent environments. Our QoC \\(^{2}\\) Breaker framework specializes circuit breakers with notions of Quality of Context to offer context-aware applications a greater stability and resilience against different types of faults. The evaluation of our framework on a prototypical case study shows that it can mitigate circumstances where isolated or transient errors can cascade into catastrophic failures throughout the whole intelligent environment, and this with a limited performance overhead."},"documents":{"kind":"list like","value":["Title: Formal modelling, knowledge representation and reasoning for design and development of user-centric pervasive software: a meta-review\nYear: 2011\n\nAbstract: Increasing demand for large scale and highly complex systems and applications, particularly with the emergence of pervasive computing and the impact of adaptive systems, introduces significant challenges for software development, as well as for user-machine interaction. Therefore, a perspective shift on software development and user-machine interaction is required. An amalgamation of model driven development and ontologies has been envisaged as a promising direction in recent literature. In this paper, we investigate this merged approach and conclude that a merger of both approaches, from formal modelling and knowledge representation perspective, on the one hand enables use of ontologies at run-time together with rules, prominently in terms of run-time reasoning, dynamic adaptations, software intelligibility, self-expressiveness, user involvement, and user situation awareness; and on the other hand at development time, prominently in terms of automated and incremental code generation, requirement adaptability, preservation of application knowledge, and validation and verification of structural and behavioural properties of the software. The core contribution of this paper lies in providing an elaborate and exploratory discussion of the problem and solution spaces along with a multidisciplinary meta-review and identification of complementary efforts in literature required to realise a merged approach.","Title: A reconfigurable component model with semantic type system for dynamic WSN applications.\nYear: 2012\n\nAbstract: Runtime reconfigurable component models provide several attractions with regard to the management of wireless sensor network (WSN) applications operating in dynamic environments and under evolving application requirements. One such attraction is the runtime discovery of suitable components for reuse in changing application compositions. Syntactic interface typing, provided by contemporary component models, however only supports exact interface matching. This causes limited reuse of components and complicates management of WSN applications. We argue that more flexibility is required to efficiently manage the complex, large-scale and dynamic WSN deployments of the future. In this paper, we describe the addition of semantic service descriptions to component interfaces to support compatibility and subtype testing. This allows rich discovery and reuse of third-party functionality and reasoning at the level of equivalent service types. We report on the incorporation of these semantic interface definitions in the Loosely Coupled Component Infrastructure (LooCI). Evaluation thereof shows that the scheme imposes minimal computational and memory overhead, while significantly reducing the complexity and cost of reconfiguration.","Title: Mobile phones assisting with health self-care: a diabetes case study\nYear: 2008\n\nAbstract: The applicability of pervasive and mobile computing in the health care sector is beyond dispute. This paper explores the use of the mobile phone as a tool for personalized health care assistance for individuals diagnosed with diabetes. By monitoring user location and activity on the mobile phone, recognizing past behavior and augmenting the logging of blood glucose levels with context data, our prototype application assists with taking well-informed decisions on daily drug dosage to achieve and maintain stable blood glucose levels. Evaluation of the prototype application indicate that a brief training of the application suffices to capture patterns in the user's relevant context that simplify glucose level trends analysis. We describe some of the details of the user study and the prototype application, and conclude with plans to investigate context-driven activity prediction to further improve the decision support for the user.","Title: Memory and communication driven spatio-temporal scheduling on MPSoCs\nYear: 2012\n\nAbstract: Scheduling and executing software efficiently on contemporary embedded systems, featuring heterogeneous multi-processors, multiple power modes, complex memory hierarchies and advanced interconnects, is a daunting task. State-of-the-art tools that schedule software tasks to hardware resources face limitations: (1) either they do not take into account the interdependancies among processing, memory and communication constraints (2) or they decouple the problem of spatial assignment from temporal scheduling. As a result existing tools make sub-optimal spatio-temporal scheduling decisions. This paper presents a technique to find globally optimized solutions by co-exploring spatio-temporal schedules for computation, data storage and communication simultaneously, considering the interdependencies between them. Experiments on mapping exploration of an image processing application on a heterogeneous MPSoC platform show that this co-exploration methodology finds schedules that are more energy efficient, when compared to decoupled exploration techniques for the particular application and target platform.","Title: Modeling Human Actors in an Intelligent Automated Warehouse\nYear: 2009\n\nAbstract: Warehouse automation has progressed at a rapid pace over the last decade. While the tendency has been to implement fully automated solutions, most warehouses today exist as a mixture of manually operated and fully automated material handling sections. In such a hybrid warehouse, men and machines move around goods in between sections in order to retrieve, transport and stack goods according to their nature and quantity. The biggest challenge in hybrid warehouses is to optimize the alignment of manual and automatic processes in order to improve the flow of materials between storage areas and distribution centers. Integrating individuals as human actors in an automation solution is not straightforward due to unpredictable human behavior. In this paper, we will investigate how we can model the characteristics of human actors within an automation solution and how software systems can unify human actors with automated business processes to coordinate both as first class entities for logistics activities within a hybrid warehouse.","Title: Teamwork on the Road: Efficient Collaboration in VANETs with Context-based Grouping.\nYear: 2011\n\nAbstract: There is an emerging trend nowadays for vehicles to be equipped with an embedded on-board computing unit with communication capabilities to enhance the overall driving experience. Such a system enables vehicle-to-vehicle and vehicle-to-infrastructure communication and provides vehicles with up-to-date route and traffic information. However, as this information is not relevant for all vehicles, context-aware communication is considered to be vital for more intelligent inter-vehicular communication. Traditional network addressing schemes are not well suited because they do not take into account contextual properties such as location, direction, speed, time and information interest for group-based communication in large scale vehicular networks. The conventional network paradigms of multicasting and broadcasting to define groups cause too much overhead. First, there is no way to optimize network traffic based on the contextual characteristics of the nodes. Second, they do not take into account the mobility patterns of the vehicles and the road layouts. We propose a context-based grouping mechanism in which only relevant information is shared among the vehicles in a group. We evaluate our approach by formulating groups based on common spatialtemporal characteristics and shared interests. The simulated experiments show that by inducing our context-based grouping mechanism we can significantly reduce the irrelevant/redundant information flows and the overall network traffic usage.","Title: Geo-social interaction: context-aware help in large scale public spaces\nYear: 2010\n\nAbstract: We present an approach to exploit social and spatio-temporal context in order to improve information dissemination in dynamic large-scale public spaces. We illustrate it by applying a proposed measure of geo-social relevance of each individual in a simulated vehicular network and by comparing the performance of different network message passing techniques in an inter-vehicle 'help-me-best-and-do-it-fast' communication scenario. We conclude that the use of social networking capabilities of an individual combined with knowledge about their spatio-temporal context information significantly improves purposeful interaction between individuals in terms of both the efficiency of the network data dissemination and the quality of the delivered information.","Title: Context-driven migration and diffusion of pervasive services on the OSGi framework\nYear: 2010\n\nAbstract: The ubiquity of wireless ad hoc networks and the benefits of loosely coupled services have fostered a growing interest in service-oriented architectures for pervasive computing. Context-aware services and runtime adaptation are key to expedite human interaction with dynamic pervasive computing environments. We explore two types of live service mobility to avoid service disruptions in mobile ad hoc networks. Service migration moves a service at runtime from one host to another including its state, while service diffusion replicates the service and the state on multiple hosts. We analyse the basic requirements for service mobility and evaluate our OSGi-based implementation for service mobility with real life experiments. Our results show that the overhead of state transfer and synchronisation is limited for relatively small applications and that the delay for handing over to a replicated service in a small scale network with enforced network failures remains minimal.","Title: An Intelligent Domotics System to Automate User Actions\nYear: 2010\n\nAbstract: Home automation systems are ambient intelligence systems that are designed to help people proactively, but sensibly. In this paper we propose a system that learns and automates patterns in the interactions of the user with the home automation devices. We will show our approach and architecture. We use an event processing tool to handle the events from the home automation devices, prediction algorithms to predict the next action and reinforcement learning to decide which action are suitable to be automated.","Title: Context-aware optimized information dissemination in large scale vehicular networks\nYear: 2010\n\nAbstract: Context-aware inter-vehicular communication is considered to be vital for inducing intelligence through the use of embedded computing devices inside vehicles. Vehicles in a scalable environment may disseminate information about certain road traffic conditions, traffic incidents, free parking space or other relevant information to the neighboring vehicles in the vicinity. In this paper, we optimize the dissemination of such context information by predicting traffic patterns in a geographical region, including traffic hotspots. We optimized the relevance backpropagation algorithm with prediction capabilities to efficiently disseminate information. We evaluate our approach with the OMNET++ network simulator using realistic large scale data sets. Our experimental results show that by optimizing information dissemination we significantly improve the Network Traffic, availability and relevant information delivery in a large scale vehicular network.","Title: The Future of Mobile E-health Application Development: Exploring HTML5 for Context-aware Diabetes Monitoring.\nYear: 2013\n\nAbstract: According to predictions of information technology research and advisory firms, such as Gartner, hybrid HTML5 appli- cations will be the future for mobile application development. In this paper, we explore the feasibility of using HTML5 and related web application standards for the development of mobile e-health applications, using a diabetes monitoring application as a practical use case. Context-awareness and visualizing multivariate data with parallel coordinates for decision support are key features of this mobile e-health application. We compare the strengths and weaknesses of the hybrid HTML5 approach with native mobile applications, and report on practical experiences with the development and usage of the application. Our experiments show that developers of fairly advanced context-aware mobile applications can definitely benefit from the HTML5 application portability across different mobile platforms. However, compared to native applications, they should be aware of missing features such as secure storage, non-negligible performance penalties of JavaScript business logic on a mobile platform, and an inferior user experience.","Title: Comparative Evaluation of Converged Service-Oriented Architectures\nYear: 2007\n\nAbstract: In this paper we evaluate and compare five commercial off-the-shelf platforms for building converged service-oriented architectures in an ambient computing environment. To this end, we have identified several categories of requirements that support the always-connected digital lifestyle of the mobile user. Key requirements are providing convergence -- joining the worlds of web services and telecom services -- and offering context awareness in order to tailor services better to the user's environment, preferences and needs. Our evaluation shows that currently none of the investigated architectures completely fulfills the two aforementioned requirements in order to deploy a variety of future converged mobile and context-aware services. However, the resulting comparison can be used as a practical guideline for decision-makers to select a platform to build a service-oriented architecture adjusted to the specific requirements within their application domain.","Title: Adaptive context management using a component-based approach\nYear: 2005\n\nAbstract: Context-awareness has become a necessity for adaptable intelligent applications and services. It is crucial for ubiquitous and pervasive computing because the context of a user or device serves as the source of information to adapt services. In this paper, we propose a modular context management system that is able to collect, transform, reason on and use context information to adapt services. By employing a component-based approach, we enable our infrastructure not only to support context-aware adaptation of services, but also to support adaptation of the context management system itself at deployment time and at runtime. This self-adaptation is based upon the service requirements and the current context of the device, such as the current resource usage or other devices in the neighborhood, resulting in an adaptive context management system for improved quality of service.","Title: Semantic and syntactic modeling of component-based services for context-aware pervasive systems using OWL-s\nYear: 2005\n\nAbstract: http://www.cs.kuleuven.ac.be Abstract. In this paper, we present a service design methodology and specification as a basis for a pervasive context-aware service infrastruc- ture. The service specification is based on the OWL-s specification, a standard proposed to add a semantic layer on top of WSDL web ser- vice descriptions. We have defined a set of OWL-s concepts that make it possible to express various pervasive service related properties, including service adaptation, relocation, personalization, deployment and runtime requirements. Though not straightforward to parse within strict resource boundaries, OWL-s provides an open, flexible specification language for expressing syntactic and semantic pervasive service characteristics and it increases service interoperability.","Title: Towards context-aware and resource-driven self-adaptation for mobile handheld applications\nYear: 2007\n\nAbstract: Mobile handheld computing is gaining momentum as more and more wireless handheld devices are being used to accomplish various computing tasks. Context-awareness can help to adapt and personalize applications or to optimize resource usage. However, many existing context infrastructures by themselves impose heavy resource requirements for deployment or highly affect the limited autonomy of the mobile device. In this paper we describe how resource-driven self-adaptation is used in our layered context-driven application middleware in order to enable deployment on a mobile device and optimize resource usage. Our evaluation shows that the introspection and intercession capabilities of the self-adapting middleware provide the necessary flexibility to achieve a balanced resource usage between the context-driven application middleware and the context-aware applications, and that the resource-driven self-adaptation is able to more than double the battery lifetime in real life scenarios.","Title: Pervasive Services on the Move: Smart Service Diffusion on the OSGi Framework\nYear: 2008\n\nAbstract: The ubiquity of wireless ad hoc networks and the benefits of loosely coupled services have fostered a growing interest in service oriented architectures for mobile and pervasive computing. Many architectures have been proposed that implement context-sensitive service discovery, selection and composition, or that use a component-based software engineering methodology to facilitate runtime adaptation to changing circumstances. This paper explores live service mobility in pervasive computing environments as a way to mitigate the risk of disconnections during service provision in mobile ad hoc networks. It focuses on context-aware service migration and diffusion to multiple hosts to increase accessibility and expedite human interaction with the service. We analyze the basic requirements for service mobility and discuss an implementation on top of OSGi. Finally, we evaluate our approach to service mobility and illustrate its effectiveness by means of a real-life scenario.","Title: Architectural backpropagation support for managing ambiguous context in smart environments\nYear: 2007\n\nAbstract: The evolution to ubiquitous information and communication networks is evident. Technology is emerging that connects everyday objects and embeds intelligence in our environment. In the Internet of Things, smart objects collect context information from various sources to turn a static environment into a smart and proactive one. Managing the ambiguous nature of context information will be crucial to select relevant information for the tasks at hand. In this paper we present a vector space model that uses context quality parameters to manage context ambiguity and to identity irrelevant context providers. We also discuss backpropagation applied in the network architecture to filter unused context information in the network as close to the source as possible. Experiments show that our contribution not only reduces the amount of useless information a smart object deals with, but also the distribution of unused context information throughout the network architecture.","Title: Towards an Extensible Context Ontology for Ambient Intelligence\nYear: 2004\n\nAbstract: To realise an Ambient Intelligence environment, it is paramount that applications can dispose of information about the context in which they operate, preferably in a very general manner. For this purpose various types of information should be assembled to form a representation of the context of the device on which aforementioned applications run. To allow interoperability in an Ambient Intelligence environment, it is necessary that the context terminology is commonly understood by all participating devices. In this paper we propose an adaptable and extensible context ontology for creating context-awaxe computing infrastructures, ranging from small embedded devices to high-end service platforms. The ontology has been designed to solve several key challenges in Ambient Intelligence, such as application adaptation, automatic code generation and code mobility, and generation of device specific user interfaces.","Title: Suitability Of Existing Service Discovery Protocols For Mobile Users In An Ambient Intelligence Environment\nYear: 2004\n\nAbstract: Service discovery enables users to access information, resources and services anytime, anywhere. This involves a client, a service provider and an infrastructure for service registration and lookup. Clients use service discovery protocols (SDPs) to issue a service request to a service registry or an individual service provider. In this paper we investigate the suitability of existing SDPs for mobile users in an ambient intelligence context. After reviewing the most well-known SDPs, common problems in the domain of user mobility and solutions that are currently available are discussed.","Title: A Loosely Coupled and Distributed Bayesian Framework for Multi-context Recognition in Dynamic Ubiquitous Environments\nYear: 2013\n\nAbstract: Today's ubiquitous environments are characterized by smart applications with variable context requirements on the one hand and a dynamic availability of heterogeneous sensors on the other hand. Currently, many existing systems pursue a structured ad-hoc approach with rigid mappings between the applications and the context sources, adversely affecting the performance of these applications when the availability of the context sources drops. Furthermore, such ad-hoc and tightly coupled approaches suffer from reduced flexibility when simultaneously handling multiple smart applications in dynamic environments characterized by a high sensor churn rate. We present a loosely coupled Bayesian-based learning framework that addresses these challenges by allowing dynamic many to many relations between smart applications and context sources with support for recognizing diverse contexts more reliably in the presence of disappearing sensors. Our approach is able to lift these limitations by leveraging the availability of multiple co occurring contexts and their conditional dependencies. On the one hand, the framework exhibits flexibility to dynamically add and remove contexts through autonomic learning of individual contexts appropriate for the spatially distributed ubiquitous infrastructures. On the other hand, it incorporates the advantages of multi-view learning by boot-strapping and fusing multiple heterogeneous context information streams. Our experimental evaluation using a personal assistant application demonstrates the performance and robustness of the proposed framework with significant adaptability and resilience to missing data and partial observability.","Title: The Right Thing to Do: Automating Support for Assisted Living with Dynamic Decision Networks\nYear: 2013\n\nAbstract: In an era where ubiquitous systems will be mainstream, users will take a more passive role and these systems will have to make smart decisions on behalf of their users. Automating these decisions in a continuously evolving dynamic context can be challenging. First of all, the right thing to do usually depends on the circumstances and context at hand. What might be a good decision today, could be a bad one tomorrow. Secondly, the system should be made aware of the impact of its decisions over time so that it can learn from its mistakes as humans do. In this paper, we formulate a technique for decision support systems to mitigate runtime uncertainty in the observed context, and demonstrate our context-driven probabilistic framework for ubiquitous systems that addresses the above mentioned challenges. Our framework incorporates end-to-end Quality of Context (QoC) as a key ingredient to make well-informed decisions. It leverages Dynamic Decision Networks (DDN) to deal with the presence of uncertainty and the partial observability of context information, as well as the temporal effects of the decisions. Our experiments with the framework demonstrate the feasibility of our approach and potential benefits to automatically make the best decision in the presence of a changing environment.","Title: Architectural styles for opportunistic mobile communication: requirements and design patterns\nYear: 2008\n\nAbstract: Mobile computing has been in the research epicenter for several decades. We have seen drastic shifts with mobile computing systems and wireless ad hoc networks dynamically adapting to create co-operating nodes that provide the right services at the right time. One aspect of such systems that has been poorly addressed is the complexity of developing applications for mobile users that require group interactions in large scale networks, especially between people unfamiliar with one another but with similar goals. Such systems need to know the type of social interaction, the context of all participants and nodes in the network, and a proper architectural design to implement scalability up to city wide networks. In this paper, we analyze which architectural styles and design patterns are the best suited the implement the various interaction requirements. We address scalability for interactions in large-scale networks from a software architectural perspective and focus on event-driven service oriented architectures to make the design of context-aware systems for large-scale mobile interactions a less complex task.","Title: Adaptive context mediation in dynamic and large scale vehicular networks using relevance backpropagation\nYear: 2008\n\nAbstract: Adaptive context mediation in large scale vehicle networks leads towards telematics which refers to the concept of vehicles equipped with context-aware embedded smart computing devices with communication capabilities over certain networks. With the use of telematics we can make use of wide range of smart inter-vehicle communication applications like emergency message transmission, collision avoidance, congestion monitoring and intelligent parking space locator. In this paper we present certain requirements for adaptive context-aware information mediation in large scale vehicle networks. We make use of quality attributes for context information and network properties of large scale vehicle networks and experiment with real time data collected using a car simulator. We simulate flooding and other dissemination based communication techniques with relevance backpropagation for large scale vehicle networks using OMNET++ to analyze the flow of context information. Our simulation results show that our context-aware and adaptive directed diffusion of information using relevance backpropagation increases the performance of the nodes in a large scale vehicle network with less communication overhead.","Title: Walking in the Clouds: Deployment and Performance Trade-Offs of Smart Mobile Applications for Intelligent Environments.\nYear: 2013\n\nAbstract: Cloud computing is still surfing the hype wave of emerging technologies. Delivering hardware, software and resources as a service over the network, the paradigm is also attracting a good deal of excitement in the mobile computing space. In this work, we challenge the proclaimed benefits of mobile cloud computing using smartphones as thin clients to access remote running applications, especially for applications that require contextual intelligence. Our experiments using mobile healthcare applications show that many resource and performance trade-offs exist and that current deployment schemes for these kind of applications are rough around the edges. We show how a modular design philosophy for mobile applications enables more optimal deployment and performance when leveraging cloud technology.","Title: Efficient Synchronization For Stencil Computations Using Dynamic Task Graphs\nYear: 2013\n\nAbstract: Executing stencil computations constitutes a significant portion of execution time for many numerical simulations running on high performance computing systems. Most parallel implementations of these stencil operations suffer from a substantial synchronization overhead. Furthermore, with the rapidly increasing number of cores these synchronization costs keep rising. This paper presents a novel approach for reducing the synchronization overhead of stencil computations by leveraging dynamic task graphs to avoid global barriers and minimizing spin-waiting, and exploiting basic properties of stencil operations to optimize the execution and memory management. Our experiments show a reduction in synchronization overhead by at least a factor four when compared to state-of-the-art stencil compilers like Pochoir and Patus.","Title: Multi-dimensional Dependency and Conflict Resolution for Self-adaptable Context-aware Systems\nYear: 2006\n\nAbstract: Self-adaptable systems dynamically adapt to satisfy new functionality requirements, to optimize performance and to adapt to variable runtime conditions. Context-aware systems acquire and utilize information about the context of a user and a device to provide personalized applications. Adaptation in a transparent way for the user is an important concern for both systems. To decrease the adaptation complexity of self-adaptable context-aware systems, we propose to model self-adaptation across three layers of abstractions: the runtime infrastructure, the context middleware and the user applications. The aim is to achieve per layer selfadaptation of the composition or behavior of these layers without jeopardizing the integrity and usability of the overall system. We discuss a multi-dimensional dependency and conflict resolution mechanism to guide self-adaptation and find a stable reconfiguration of the system at runtime.","Title: Evaluation framework for adaptive context-aware routing in large scale mobile peer-to-peer systems\nYear: 2011\n\nAbstract: The proliferation of novel wireless network technologies creates new opportunities for complex peer-to-peer information dissemination\n systems. A key challenge that remains in this area is how to select the best algorithms and protocols to communicate effectively\n on a large scale. In this paper, we focus in particular on large scale mobile networks where effectiveness depends on the\n requirements of the application at hand and on the context of the peers in the network. We propose a framework for context-aware\n adaptive information sharing that allows the evaluation of and comparison with alternative information routing protocols using\n network metrics to measure a variety of quality attributes of the information dissemination protocols. These metrics can then\n be used to verify which protocol is best suited for a particular application. We illustrate our evaluation framework with\n different information dissemination protocols in an inter-vehicle communication scenario.","Title: Encoding Semantic Awareness in Resource-Constrained Devices\nYear: 2008\n\nAbstract: With the Semantic Web relying on ontologies to establish online machine-interpretable information, the Internet is growing into a semantically aware computing paradigm that facilitates Web entities' discovery of the knowledge and resources they need. Ambient intelligence aims to enable smart interaction beyond the Internet by embedding intelligence into our environment to unobtrusively support users' daily activities. To accomplish these goals, ontologies and semantic awareness are crucial for better understanding a user's context. While interest in the Semantic Web has spurred the development of large-scale semantic grid architectures, expanding the Semantic Web to the other end of the computing spectrum is a complex undertaking. The techniques and tools that support the Semantic Web aren't designed to deal with the resource-constrained devices with which people frequently interact in an ambient-intelligence environment. A proposed coding scheme for ontologies embeds semantic awareness in devices with limited memory and processing capabilities, such as sensory nodes and smart phones. This scheme provides a compact representation of an ontology and is enhanced with an efficient and effective semantic-matching algorithm similar to subsumption testing in many ontology reasoners.","Title: A survey of software engineering best practices for the development of smart applications in Ambient Intelligence\nYear: 2012\n\nAbstract: Over the past decade, the world of Ambient Intelligence and smart environments has brought us a wide variety of novel applications with potential for exhibiting sophisticated intelligent behavior. These applications are called smart because they can sense, anticipate and adapt themselves to the context, desires and intentions of their users. However, the unpredictability of human behavior, the unanticipated circumstances of execution and a growing heterogeneity of future operational environments impose significant development challenges if these innovative applications are to gain wide acceptance in our daily life. Therefore, applying well-established software engineering methodologies is a fundamental prerequisite for delivering high quality and robust smart software applications. This survey provides a illustrative presentation of software engineering best practices in the area of smart environments and Ambient Intelligence. The aim of this survey is not to explore and compare every possible related work in detail, but to offer insights into the latest developments in this domain and to further the research into the successful design, development and evaluation of Ambient Intelligence frameworks and applications. (This research is partially funded by the Interuniversity Attraction Poles Programme Belgian State, Belgian Science Policy, and by the Research Fund KU Leuven.)","Title: Intelligent Widgets for Intuitive Interaction and Coordination in Smart Home Environments\nYear: 2012\n\nAbstract: The intelligent home environment is a well-established example of the Ambient Intelligence application domain. A variety of sensors and actuators can be used to have the home environment adapt towards changing circumstances and user preferences. However, the complexity of how these intelligent home automation systems operate is often beyond the comprehension of non-technical users, and adding new technology to an existing infrastructure is often a burden. In this paper, we present a home automation framework designed based on smart widgets with a model driven methodology that raises the level of abstraction to configure home automation equipment. It aims to simplify user-level home automation management by mapping high-level home automation concepts onto a low-level composition and configuration of the automation building blocks with a reverse mapping to simplify the integration of new equipment into existing home automation systems. Experiments have shown that the mappings we proposed are sufficient to represent household appliances to the end user in a simple way and that new mappings can easily be added to our framework.","Title: EASY: Efficient semAntic Service discoverY in pervasive computing environments with QoS and context support\nYear: 2008\n\nAbstract: Pervasive computing environments are populated with networked software and hardware resources providing various functionalities that are abstracted, thanks to the Service Oriented Architecture paradigm, as services. Within these environments, service discovery enabled by service discovery protocols (SDPs) is a critical functionality for establishing ad hoc associations between service providers and service requesters. Furthermore, the dynamics, the openness and the user-centric vision aimed at by the pervasive computing paradigm call for solutions that enable rich, semantic, context- and QoS-aware service discovery. Although the semantic Web paradigm envisions to achieve such support, current solutions are hardly deployable in the pervasive environment due to the costly underlying semantic reasoning with ontologies. In this article, we present EASY to support efficient, semantic, context- and QoS-aware service discovery on top of existing SDPs. EASY provides EASY-L, a language for semantic specification of functional and non-functional service properties, as well as EASY-M, a corresponding set of conformance relations. Furthermore, EASY provides solutions to efficiently assess conformance between service capabilities. These solutions are based on an efficient encoding technique, as well as on an efficient organization of service repositories (caches), which enables both fast service advertising and discovery. Experimental results show that the deployment of EASY on top of an existing SDP, namely Ariadne, enhancing it only with slight changes to EASY-Ariadne, enables rich semantic, context- and QoS-aware service discovery, which furthermore performs better than the classical, rigid, syntactic matching, and improves the scalability of Ariadne.","Title: Where people and cars meet: social interactions to improve information sharing in large scale vehicular networks\nYear: 2010\n\nAbstract: Efficient delivery of information in vehicular networks is crucial for the creation of useful and usable applications that need to cope with nomadic large-scale environments. Context-awareness is often key to improve efficiency of a vehicle network since it allows to make informed decisions on the data routing, data locality and data necessity for different moving objects. In this paper we show how the social network of vehicle residents, as part of the overall context, allows us to improve the information sharing in the vehicular network significantly. We demonstrate this by deploying a social ubiquitous-help-system (UHS) on top of a vehicular network. We analyze how UHS operates in a vehicular network using a network simulation of realistic large scale vehicular movement data and show that the social interactions increases the efficiency, relevance and quality of information in data delivery.","Title: A DSL for Context Quality Modeling in Context-Aware Applications.\nYear: 2011\n\nAbstract: Developing reliable context-aware applications remains a big challenge, even after a decade of research in this area. Usually a lot of code is required to handle an application's correct behavior in a variety of different situations. Along with a growing amount of code, also increases the risk of programming errors that may lead to an undesired behavior in particular situations. In this paper we present a domain specific language (DSL) for developing context-aware applications. It allows creating context quality models which are transformed into software artifacts of the final application. This code generation saves time and effort, and helps to ensure an appropriate autonomic behavior at runtime in inherently uncertain situations.","Title: A notion of event quality for contextualized planning and decision support systems\nYear: 2011\n\nAbstract: This paper presents an approach for contextualizing an event-based decision support system for scheduling patient assessments in a hospital. To cope with unexpected delays, patient coordinators often pursue a worst case scenario when scheduling patient assessments, leading to an underutilization of human resources and equipment when the procedure went without complications. We present a context-based decision support system for patient planning that helps the patient coordinator with taking well-informed rescheduling decisions and anticipating changes in other patients' schedules. The system uses information and events produced by medical equipment. As these events can be nondeterministic, we demonstrate how our domain specific context model can be used to contextualize events to enhance their quality and ascertain their meaning.","Title: A User-Oriented and Context-Aware Service Orchestration Framework for Dynamic Home Automation Systems\nYear: 2010\n\nAbstract: The home environment has become increasingly sophisticated. Sensors and actuators allow a house to he programmed so that it can intelligently adapt to user needs. Unfortunately it has not become any easier for the user to manage all these devices. Our ontology driven framework describes a user-oriented automation system to help with this process by not only orchestrating home automation devices, but also by integrating new equipment and automating them as much as possible. By combining devices with a common functionality in a given context, relevant devices are pulled together in an intuitive user interface in which one can express preferences at a high level of abstraction. The big advantage is that our framework allows for the home environment to be adjusted without the user having to know about the technical details of devices in the home automation system.","Title: Quality Extensions and Uncertainty Handling for Context Ontologies\nYear: 2006\n\nAbstract: Context, by nature, involves real world entities and is therefore subject to uncertainty and inaccuracies. Ontologies are of- ten used to model context in a formal way in order to achieve a shared semantic understanding of concepts and the relationships that hold among them. However, they lack support for representing am- biguous context and appropriate comparison algorithms. As such, context-aware applications may make the assumption that the con- text they use is completely accurate. In this paper we propose a sim- ple and lightweight yet generic approach to extend context ontolo- gies with quality of context properties and discuss the use of these quality properties for context ontology matching under uncertainty using fuzzy set theory. We illustrate the proposed extensions and un- certainty mechanisms with a small example where uncertain spatio- temporal coverage is combined with other contextual properties.","Title: Analyzing the efficiency of context-based grouping on collaboration in VANETs with large-scale simulation.\nYear: 2014\n\nAbstract: Vehicle-to-vehicle and vehicle-to-infrastructure communication systems enable vehicles to share information captured by their local sensors with other interested vehicles. To ensure that this information is delivered at the right time and location, context-aware routing is vital for intelligent inter-vehicular communication. Traditional network addressing and routing schemes do not scale well for large vehicular networks. The conventional network multicasting and broadcasting cause significant overhead due to a large amount of irrelevant and redundant transmissions. To address these challenges, we first take into account contextual properties such as location, direction, and information interest to reduce the network traffic overhead. Second, to improve the relevancy of the received information we leverage the mobility patterns of vehicles and the road layouts to further optimize the peer-to-peer routing of the information. Third, to ensure our approach is scalable, we propose a context-based grouping mechanism in which relevant information is shared in an intelligent way within and between the groups. We evaluate our approach based on groups with common spatio-temporal characteristics. Our simulation experiments show that our context-based routing scheme and grouping mechanism significantly reduces the propagation of irrelevant and redundant information.","Title: Learning distributed deployment and configuration trade-offs for context-aware applications in Intelligent Environments.\nYear: 2014\n\nAbstract: The Internet of Things (IoT) is rapidly gaining ground as can be witnessed by the pervasive presence of the many things or objects around us that turn our surroundings into Intelligent Environments. These objects interact on a large scale in wired and wireless sensor and actuator networks using advanced communication protocols. Hence, IoT is an open ended and highly dynamic ecosystem with heterogeneous workloads and fluctuating resource availability. Distributed intelligence for smart objects and platforms is a vital enabling factor for IoT, but finding the best strategy to deploy and configure applications - especially those that require contextual intelligence - in a smart environment with dynamic and heterogeneous resource availability is far from straightforward. Our experiments using context-aware applications for Intelligent Environments show that many resource and performance trade-offs exist and that current deployment schemes for these kind of applications are rough around the edges. We illustrate how a modular design philosophy for smart IoT applications enables a more optimal deployments. Furthermore, we present a methodology to inspect and learn the trade-offs of different deployment schemes of IoT applications in order to autonomously optimize their configuration. We validated our methodology on different use cases and scenarios, and the results demonstrate the feasibility of our approach to automate the efficient deployment of IoT applications in the presence of multiple conflicting Quality of Service (QoS) objectives and varying runtime circumstances.","Title: A Quality-aware Federated Framework for Smart Mobile Applications in the Cloud.\nYear: 2014\n\nAbstract: Mobile Cloud Computing is an active research domain to investigate the ways of achieving a federation between mobile computing and cloud computing. Whereas, Ambient Intelligence aims to teach our mobile devices how to behave smart in our environment, narrowing the gap between people, their devices and the environment. These two domains behave as backbone for ubiquitous environment around us where everything is connected by sharing information and resources. Mobile devices use cloud resources to cope with ever-growing computing and storage demands for smart applications. Context provisioning in the cloud and mobile connectivity will give rise to new interactions with cloud infrastructure to effectively manage context information. However, as a lot of contextual information is being sensed and captured by mobile devices, it is not always clear whether it makes sense to upload all the raw sensed data to the cloud and have it processed there. Many resource and performance trade-offs exist for federated deployment of smart mobile applications. In this paper, we present a quality-aware federated framework to overcome the challenges for smart applications and to support the development and deployment of these applications, while opportunistically using cloud computing. The framework highlights the aspects of Quality-of-Context (QoC) provisioning and dynamic adaptability under uncertain context.","Title: Enabling Self-learning in Dynamic and Open IoT Environments.\nYear: 2014\n\nAbstract: The next big thing in computing is the Internet of Things (IoT), referring to dynamic and ever-evolving environments, generating high-volume streams of heterogeneous yet correlated contextual information of varying quality and complexity. Moreover, the increase in user mobility and unreliable sensor availability in IoT, necessitates the context-aware applications to dynamically adapt their behavior at run time. In this paper, we elicit the need for different self-learning techniques to tackle the openness of the IoT environments and propose enabling algorithms to achieve them. First, we present possible application scenarios which can benefit from both supervised and unsupervised self-learning. Later, we propose correlation mining algorithms based on Kullback-Leibler (KL) divergence and frequent set mining that exploits correlated contexts to enable unsupervised self-learning. These algorithms help to identify alternate sources for a context and semantically describe the previously unseen contexts in terms of already known contexts. We have realized the proposed algorithms on top of a Bayesian framework (HARD-BN) which supports autonomous learning. Our experiments demonstrate the applicability of the proposed correlation mining algorithms and their feasibility to enable self-learning in open and ever-evolving IoT environments.","Title: Types in Their Prime: Sub-typing of Data in Resource Constrained Environments.\nYear: 2013\n\nAbstract: Sub-typing of data improves reuse and allows for reasoning at different levels of abstraction; however, it is seldom applied in resource constrained environments. The key reason behind this is the increase in overhead that is caused by including hierarchical information in data types as compared to a flat list. Where hierarchical data typing is used, it is often represented using verbose textual identifiers or numerical encodings that are suboptimal with regards to space. In this paper, we present an encoding function for hierarchically typed information, based on the properties of prime numbers. It provides a compact representation of types, fast subsumption testing even on resource constrained platforms and support for the evolution of the data type hierarchy. We demonstrate the feasibility of our approach on two representative communication models in constrained environments; a publish/subscribe event bus and a RESTful application protocol. We evaluate the performance of our encoding function and show that it has limited overhead compared to a flat list of data types and that this overhead is outweighed by reduced memory and communication overhead once applied.","Title: Design for Failure: Intelligent Systems Learning from Their Mistakes.\nYear: 2014\n\nAbstract: Smart environments aim to make the life of their inhabitants more comfortable by having context-aware systems continuously work together to assist people with their daily tasks. However, all too often these assistive technologies are naively or optimistically developed assuming that systems can always anticipate what users want. Furthermore, the more these smart systems grow in complexity, the more prone to failure they become. The overall goal of this paper is to define new concepts and methodologies for the development of more reliable smart applications, and propose middleware support to analyze failures in context-aware behavior, culminating in a software-based safeguard that improves robustness against unforeseen human interventions, exceptional circumstances and unexpected events.","Title: Scalar: A Distributed Scalability Analysis Framework\nYear: 2014\n\nAbstract: Analyzing the scalability and quality of service of large scale distributed systems, such as cloud based services, requires a systematic benchmarking framework that is at least as scalable to sufficiently stress the system under test. This paper summarizes Scalar, our distributed, extensible load testing tool that can generate high request volumes using multiple coordinated nodes. It has support for communication and synchronization between user threads, and built-in node monitoring to detect resource bottlenecks in the benchmark framework deployment itself. Furthermore, it offers highly scalable results analysis that exploits data locality and characterizes the overall system scalability in terms of the Universal Scalability Law.","Title: Scalability Analysis of the OpenAM Access Control System with the Universal Scalability Law\nYear: 2014\n\nAbstract: The scalability of a software system is greatly impacted by the scalability of the underlying access control system, which makes analyzing the scalability of that access control system paramount. However, this is not trivial, as contemporary access control systems have a myriad of architectural deployment variations, each of which has a potentially large impact on overall system throughput. There is a need for a systematic approach to map these architectural variations to a reference model which allows to make comparisons and to identify trade-offs. This work provides a piece of the puzzle by demonstrating how this can be achieved by systematically applying the Universal Scalability Law (USL). We illustrate our approach by performing a rigorous scalability analysis of the OpenAM access control system for various deployment alternatives in the domain of authentication. We conclude that the approach is able to provide both qualitative and quantitative results which can be translated into practical operational recommendations for the envisioned types of system deployments.","Title: Scalar: Systematic Scalability Analysis with the Universal Scalability Law\nYear: 2014\n\nAbstract: Analyzing the scalability and quality of service of large scale distributed systems requires a highly scalable benchmarking framework with built-in communication and synchronisation functionality, which are features that are lacking in current load generation tools. This paper documents Scalar, our distributed, extensible scalability analysis tool that can generate high request volumes using multiple communicating, coordinated nodes. We show how Scalar offers analytics capabilities that support the Universal Scalability Law. We illustrate Scalar on an electronic payment case study, and find that the framework supports complex work flows and is able to characterize and give predictive insights into the quality of service and relative capacity of the system under test in function of the user load.","Title: SAMURAI: A Streaming Multi-tenant Context-Management Architecture for Intelligent and Scalable Internet of Things Applications\nYear: 2014\n\nAbstract: In the Internet of Things, heterogeneous and distributed streams of sensor events is a driver for context-aware behavior in intelligent environments. However, processing the event data usually cross-cuts the business logic of IoT applications and offering such reusable functionality as a service towards a variety of customers with different needs is often faced with scalability concerns. We present SAMURAI, a multi-tenant streaming context architecture that integrates and exposes well-known components for complex event processing, machine learning, knowledge representation, NoSQL persistence and in-memory data grids. SAMURAI pursues a twofold approach to achieve scalability: (1) distributed deployment with horizontal scalability, (2) shared resources through multi-tenancy. For the scenario used in the experimental evaluation of our architecture, the results show little overhead to support multi-tenancy, with near-linear scalability and flexible elasticity for deployment schemes with data partitioning per tenant.","Title: When efficiency matters: Towards quality of context-aware peers for adaptive communication in VANETs\nYear: 2011\n\nAbstract: In the near future vehicles will be equipped with embedded communication capabilities in order to perform context-sensitive tasks such as traffic flow control and incident avoidance. In large scale vehicular networks it is of vital importance that the information exchanged between the vehicles meets a certain level of quality so that they can make informed automated decisions. In this paper we define Quality of Context (QoC) and Peer Reputation (PR) for nodes in vehicular networks and propose ways to apply them for efficient communication. Thus, we provide a two-fold solution in which on the one hand we focus on the quality of the information and on the other hand we aim at determining the reputation of the nodes involved in the communication. This helps to eliminate the use of erroneous, ambiguous and imprecise information provided by unknown entities. Our simulated experiments show that our mechanism significantly reduces network traffic usage, eases out the decision making process and guarantees a minimum level of quality.","Title: SAMURAI: A batch and streaming context architecture for large-scale intelligent applications and environments.\nYear: 2016\n\nAbstract: Over the past decade intelligent environments have grown in sophistication. Many recent paradigm shifts - such as the Internet of Things (IoT), Ambient Assisted Living (AAL), e-health and telemedicine - envision large distributed networks of intelligent devices, applications and services that are sensitive to the presence of people and responsive to their needs. Cutting edge technologies will autonomously and collectively operate on a growing volume of information arriving at ever increasing velocities to transparently and non-intrusively support users during their activities. Especially the escalating variety of information that applications have to deal with is a non-trivial concern. Making sense out of heterogeneous and pervasive streams of sensor events to anticipate and address the needs of users is a ubiquitous challenge that many interactive context-aware applications in intelligent environments frequently face. Furthermore, software solutions that continuously interpret the tasks and contexts of a variety of individuals with different needs are often faced with scalability concerns. We present SAMURAI, a batch and streaming context architecture that integrates and exposes well-known components for complex event processing, machine learning, and knowledge representation. SAMURAI builds upon key concepts of the Lambda architecture and big data enabling technologies to achieve horizontal scalability and responsive interaction with its users. Two application cases validate the feasibility and performance of our context architecture, demonstrating near-linear scalability, flexible elasticity and smooth interaction capabilities.","Title: Mobile device fingerprinting considered harmful for risk-based authentication\nYear: 2015\n\nAbstract: In this paper, we present a critical assessment of the use of device fingerprinting for risk-based authentication in a state-of-practice identity and access management system. Risk-based authentication automatically elevates the level of authentication whenever a particular risk threshold is exceeded. Contemporary identity and access management systems frequently leverage browser-based device fingerprints to recognize trusted devices of a certain individual. We analyzed the variability and the predictability of mobile device fingerprints. Our research shows that particularly for mobile devices the fingerprints carry a lot of similarity, even across models and brands, making them less reliable for risk assessment and step-up authentication.","Title: PRISM: Policy-driven Risk-based Implicit locking for improving the Security of Mobile end-user devices.\nYear: 2015\n\nAbstract: Nowadays, most mobile applications rely on device screen locking mechanisms for ensuring practical security, which expects the users to explicitly authenticate with a PIN or biometric irrespective of the perceived threats. Owing to this usability issues, many avoid using device locks potentially compromising the security. To overcome the limitations of this binary approach, we present an implicit authentication framework called PRISM (Policy-driven Risk-based Implicit locking for improving the Security of Mobile end-user devices). It provides risk based authentication by detecting anomalies in the usual behavior patterns of the users which include their expected locations, activities and application usage. Its device unlocking decisions are driven by policies that are defined either automatically by mining sensor data or manually by the end-users. Our experiments show that PRISM is able to discover useful behavior patterns efficiently even with limited data. The number of required explicit authentications is significantly reduced while assuring the preferred security for everyday scenarios.","Title: SmartAuth: dynamic context fingerprinting for continuous user authentication\nYear: 2015\n\nAbstract: As recent incidents have shown, weak passwords are a severe security risk for authenticating users and granting access to protected resources. Additionally, strong passwords score low on usability, especially on mobile devices. In this work, we present SmartAuth, a scalable context-aware authentication framework built on top of OpenAM, a state-of-practice identity and access management suite. It uses adaptive and dynamic context fingerprinting based on Hoeffding trees to continuously ascertain whether a user's identity is authentic or not, and it respects privacy preferences by adopting consent-driven use of context information. We assess our approach from both an offensive and defensive security perspective. Our results show that dynamic context fingerprinting has good potential for a zero-interaction authentication scheme, with a minimal performance overhead compared to traditional authentication schemes.","Title: To cloud or not to cloud: a context-aware deployment perspective of augmented reality mobile applications\nYear: 2015\n\nAbstract: The resource limitations of mobile devices continue to impose constraints on the development of complex mobile applications. Performance and resource efficiency remains a challenge. We have examined resource utilization and performance trade-offs when extending an Augmented Reality (AR) application with context-awareness and cloud computing. The hypothesis is that the cost of these technologies is worth the benefits they result in. Our measurements show that filtered image datasets obtained through context-awareness result in lower latency and a reduced memory load when performing all AR computations on the mobile device. However, a cloud computing AR application does not benefit from in-depth context-awareness, as no part of the dataset is stored locally and the latency is approximately constant, relative to the Internet connectivity.","Title: SparkXS: Efficient Access Control for Intelligent and Large-Scale Streaming Data Applications\nYear: 2015\n\nAbstract: The exponential data growth in intelligent environments fuelled by the Internet of Things is not only a major push behind distributed programming frameworks for big data, it also magnifies security and privacy concerns about unauthorized access to data. The huge diversity and the streaming nature of data raises the demand for new enabling technologies for scalable access control that can deal with the growing velocity, volume and variety of volatile data. This paper presents SparkXS, an attribute-based access control solution with the ability to define access control policies on streaming latent data, i.e. hidden information made explicit through data analytics, such as aggregation, transformation and filtering. Experimental results show that SparkXS can enforce access control in a horizontally scalable way with minimal performance overheads.","Title: Change Impact Analysis for Context-Aware Applications in Intelligent Environments.\nYear: 2015\n\nAbstract: As software systems for context-aware applications and intelligent environments become increasingly complex and adaptive, the need to understand and predict the impact of changes grows. Such changes may manifest themselves (1) as alterations in the way users behave, (2) as software customizations to handle new requirements, and (3) as variations on the dynamic context in which intelligent environment systems are deployed and operate. Such internal and external changes may be anticipated or unforeseen in nature. With reliability being a key concern for intelligent environments, we revisit in this work the state-of-practice on change impact analysis (CIA) - a well-known methodology in software engineering - and investigate to what extent it can be applied and enhanced to contribute to the development of more reliable context-aware adaptive applications to increase the confidence in intelligent environment systems.","Title: Accelerometer-Based Device Fingerprinting for Multi-factor Mobile Authentication.\nYear: 2016\n\nAbstract: Due to the numerous data breaches, often resulting in the disclosure of a substantial amount of user passwords, the classic authentication scheme where just a password is required to log in, has become inadequate. As a result, many popular web services now employ risk-based authentication systems where various bits of information are requested in order to determine the authenticity of the authentication request. In this risk assessment process, values consisting of geo-location, IP address and browser-fingerprint information, are typically used to detect anomalies in comparison with the user's regular behavior. In this paper, we focus on risk-based authentication mechanisms in the setting of mobile devices, which are known to fall short of providing reliable device-related information that can be used in the risk analysis process. More specifically, we present a web-based and low-effort system that leverages accelerometer data generated by a mobile device for the purpose of device re-identification. Furthermore, we evaluate the performance of these techniques and assess the viability of embedding such a system as part of existing risk-based authentication processes.","Title: Adaptive Dissemination For Mobile Electronic Health Record Applications With Proactive Situational Awareness\nYear: 2016\n\nAbstract: Bring Your Own Device (BYOD) has been an emerging trend in the enterprise, including the healthcare domain. However, efficient and personalized content delivery for data intensive applications remains a technical challenge. In this work, we explore a mobile electronic health record (EHR) web application for general practitioners (GPs) on the mad for patient visits. Keeping all the health records up to date on a tablet is impossible due to resource constraints of the device, and dynamic planning of home visits. We therefore investigate how to deliver the right information at the right time under variable connectivity and limited resource availability. We present a flexible framework that capitalizes on situational awareness for proactive and adaptive content delivery to mobile applications. It leverages distributed probabilistic models and dynamic decision networks to improve the overall user experience with better on-device resource utilization. The added value is that it lifts the burden from the GP to customize and personalize the application by learning data consumption patterns in different contexts. Compared to baseline scenarios for this particular use case, our framework shows an improvement in the precision and recall with an acceptable runtime overhead for memory and CPU.","Title: Feature-Based Variability Management For Scalable Enterprise Applications: Experiences With An E-Payment Case\nYear: 2016\n\nAbstract: In today's world of electronic payments, which includes credit cards, gift cards, stored value accounts, and micro payments on mobile devices, successful payment services need to be sufficiently scalable and support diverging use cases to be successful. However, the interaction between horizontal scalability, feature variability and stringent performance and security concerns for these heterogeneous payment applications and stakeholders is not always cleat; which creates tension (and sometimes interference) in the successful development of these services. In this work, we identify crucial nonfunctional requirements for payment services and present a simple framework to map these requirements to existing approaches to achieve both horizontal and vertical scalability. We report on experiences with applying a service line engineering (SLE) approach towards payment services that combines cloud computing and SPL to support feature customization in a multi tenant payment service. We conclude with practical experiences and several lessons learned after applying this SPL engineering methodology on our industrial e-payment use case.","Title: Mascot: Self-Adaptive Opportunistic Offloading For Cloud-Enabled Smart Mobile Applications With Probabilistic Graphical Models At Runtime\nYear: 2016\n\nAbstract: Although extensive progress has been made in Mobile Cloud Augmentation, automated decision support on the device that enables the opportunistic and intelligent use of cloud resources is missing. Furthermore, we need solutions with reflective capabilities that can handle a changing environment and runtime variability. To simplify the deployment of smart mobile applications, we present a framework with retrospective decision support based on reinforcement learning to cater for various resource-performance trade-offs. We have adopted the MAPE-K (Monitor-Analyse-Plan-Execute-Knowledge) control loop architecture and realized the loop with Dynamic Decision Networks to manage self-adaptation at runtime. Our experiments show that our framework is capable of intelligently inferring appropriate decisions with an acceptable performance overhead of 10 milliseconds on mobile devices.","Title: Security and privacy controls for streaming data in extended intelligent environments.\nYear: 2016\n\nAbstract: Intelligent environments collect and process personal information to assist individuals with their daily activities, enhance their experiences and adapt to their needs and intentions. The prosperity of paradigms like the Internet of Things (IoT) will boost the development of intelligent environments, but the envisioned exponential data growth will give rise to serious security and privacy concerns. Already in the domains of smart homes and healthcare one can observe a growing trend of intelligent environments being extended with third party smart service and technology providers-such as cloud and Big Data analytics services-that analyze and visualize sensitive information as a means to offer new insights to their customers, but that typically cross the personal space or privacy boundaries of the intelligent environment. The challenge addressed in this work is how to offer Big Data processing capabilities as a service with appropriate data protection safeguards in order to protect the individual's privacy in the extended intelligent environment. In this paper, we present SparkXS, a framework which offers granular and scalable access and data protection control on streaming data that can deal with the growing velocity, volume and variety of volatile data of IoT, integrated on top of our SAMURAI lambda architecture for Big Data processing. Driven by upcoming legislation and obligations, such as the EU General Data Protection Regulation (GDPR), our framework applies Privacy by Design (PbD) strategies and offers security controls that empower users to better control their personal data. Experimental results with motivating use cases and large data sets demonstrate the feasibility and scalability of our SparkXS framework while operating with acceptable performance overheads.","Title: Privacy-enabled remote health monitoring applications for resource constrained wearable devices.\nYear: 2016\n\nAbstract: Recent computing paradigms like cloud computing and big data have become very appealing to outsource computation and storage, making it easier to realize personalized and patient centric healthcare through real-time analytics on user data. Although these technologies can significantly complement resource constrained mobile and wearable devices to store and process personal health information, privacy concerns are keeping patients from reaping the full benefits. In this paper, we present and evaluate a practical smart-watch based lifelog application for diabetics that leverages the cloud and homomorphic encryption for caregivers to analyze blood glucose, insulin values, and other parameters in a privacy friendly manner to ensure confidentiality such that even a curious cloud service provider remains oblivious of sensitive health data.","Title: A model-driven approach for quality of context in pervasive systems.\nYear: 2016\n\nAbstract: A proposal for modeling quality of context (QoC) for pervasive systems is presented.The MLContext modeling language is extended to support QoC.A Model-Driven approach is applied to generate software artefacts related to QoC.The proposal has been validated for the COSMOS and SAMURAI context-aware frameworks. Handling context is a crucial activity in context-aware systems. In building such systems, the creation of models helps developers to understand and reason on the context information. The quality of context information is required to achieve these systems behavior according to the requirements. Therefore, context models should not only represent the context information but also the quality of context (QoC). MLContext is a textual domain-specific language (DSL) designed to model context, which has been used to automatically generate software artifacts related to the context management for some context-aware frameworks. In this article we present an MLContext extension for modeling QoC. The QoC added features include constructs to express context situations (i.e. constraints on context information), quality requirements and quality levels. The new constructs have been mapped to code for two frameworks supporting QoC (COSMOS and SAMURAI). These mappings have been validated by means of a case study.","Title: Data Protection Compliance Regulations and Implications for Smart Factories of the Future\nYear: 2016\n\nAbstract: Context-aware systems in intelligent environments digest large amounts of data and personal information to gain situational awareness as a way to assist individuals with their daily activities, enhance their experiences and adapt to their needs and intention, whenever and wherever they are. Large amounts of data drive these environments, motivating the adoption of big data and cloud technologies. A similar digital transformation is taking place in the Factory of the Future and Industry 4.0, two paradigms on creating smart products through smart processes and procedures. As the attack surface for security and privacy threats grows, it is no surprise that new regulations and directives will be put in place to protect the privacy of individuals. In this paper, we discuss the foundational principles of Privacy by Design and key obligations of the upcoming EU General Data Protection Regulation (GDPR), and highlight how they impact the design and development of context-aware intelligent environments. We provide technical guidelines for better compliance with these regulatory frameworks.","Title: Leveraging Battery Usage from Mobile Devices for Active Authentication.\nYear: 2017\n\nAbstract: Active authentication is the practice of continuously verifying the identity of users, based on their context, interactions with a system, and information provided by that system. In this paper, we investigate if battery charge readings from mobile devices can be used as an extra factor to improve active authentication. We make use of a large data set of battery charge readings from real users and construct two computationally inexpensive machine learning classifiers to predict if a user session is authentic: the first one only based on the battery charge at a certain time of day; the second one predicts the authenticity of the user session when a previous, recent battery charge reading is available. Our research shows that a simple two-figure battery charge value can make a useful albeit minor contribution to active authentication.","Title: The intelligent industry of the future: A survey on emerging trends, research challenges and opportunities in Industry 4.0.\nYear: 2017\n\nAbstract: Strongly rooted in the Internet of Things and Cyber-Physical Systems-enabled manufacturing, disruptive paradigms like the Factory of the Future and Industry 4.0 envision knowledge-intensive industrial intelligent environments where smart personalized products are created through smart processes and procedures. The 4th industrial revolution will be based on Cyber-Physical Systems that will monitor, analyze and automate business processes, transforming production and logistic processes into smart factory environments where big data capabilities, cloud services and smart predictive decision support tools are used to increase productivity and efficiency. This survey provides insights into the latest developments in these domains, and identifies relevant research challenges and opportunities to shape the future of intelligent manufacturing environments.","Title: Quality Parameters as Modeling Language Abstractions for Context-Aware Applications: An AAL Case Study.\nYear: 2017\n\nAbstract: The quality of context information is still one of the most overlooked factors by developers and end-users, and this makes context-aware applications less reliable. While there is recent work in this area that focuses on identifying and modeling relevant quality parameters for context information, software developers still have not yet adopted these solutions at large because they do not offer the right set of abstractions that they are familiar with. This paper presents model and language constructs, as well as software engineering tools to address these quality of context concerns. We demonstrate our overarching solution on a non-trivial Ambient Assisted Living scenario involving assistance services for the elderly supported by indoor localization technologies.","Title: Enhanced fraud detection as a service supporting merchant-specific runtime customization.\nYear: 2017\n\nAbstract: We present a customizable, yet scalable data processing architecture for payment processors that aim to offer fraud detection as a service to e-commerce merchants. Due to the increasing complexity of payment solutions and the continuous evolution of fraud patterns, rule-based detection of fraudulent payments is no longer adequate. Our solution is implemented as a K-architecture for streaming big data, augmented with semantic web techniques to enable constrained customization for merchants. Our evaluation shows that our data processing architecture meets the stringent real-time processing limits of payment transactions, while offering runtime customization for multiple merchants.","Title: Identity management for cyber-physical production workflows and individualized manufacturing in industry 4.0.\nYear: 2017\n\nAbstract: Industry 4.0 envisions a digital transformation in the enterprise, entwining the cyber-physical world and real world of manufacturing to deliver networked production with enhanced process transparency. Production systems, smart products, data analytics and business processes in the cloud will interact directly with customers to realize the ambitious goal of single lot individualized manufacturing. An immediate consequence of the paradigm shift is an increased risk for cyber-security breaches. This paper presents and evaluates the performance and scalability of an identity management solution for dataflow-oriented processes to guarantee the authenticity and trustworthy access of users, machines, products and business processes in Industry 4.0 production workflows that operate across the organizational boundaries of the enterprise.","Title: CEML: Mixing and moving complex event processing and machine learning to the edge of the network for IoT applications.\nYear: 2016\n\nAbstract: The Internet of Things (IoT) is a growing field which is expected to generate and collect data everywhere at any time. Highly scalable cloud analytics systems are frequently being used to handle this data explosion. However, the ubiquitous nature of the IoT data imposes new technical and non-technical requirements which are difficult to address with a cloud deployment. To solve these problems, we need a new set of development technologies such as Distributed Data Mining and Ubiquitous Data Mining targeted and optimized towards IoT applications. In this paper, we present the Complex Event Machine Learning framework which proposes a set of tools for automatic distributed machine learning in (near-) real-time, automatic continuous evaluation tools, and automatic rules management for deployment of rules. These features are implemented for a deployment at the edge of the network instead of the cloud. We evaluate and validate our approach with a well-known classification problem.","Title: A dynamic decision fusion middleware for trustworthy context-aware IoT applications.\nYear: 2017\n\nAbstract: Internet of Things (IoT) devices offer new sources of contextual information, which can be leveraged by applications to make smart decisions. However, due to the decentralized and heterogeneous nature of such devices - each only having a partial view of their surroundings - there is an inherent risk of uncertain, unreliable and inconsistent observations. This is a serious concern for applications making security related decisions, such as context-aware authentication. We propose and evaluate a middleware for IoT that provides trustworthy context for a collaborative authentication use case. It abstracts a dynamic and distributed fusion scheme that extends the Chair-Varshney (CV) optimal decision fusion rule such that it can be used in a highly dynamic IoT environment. We compare performance and cost trade-offs against regular CV. Experimental evaluation demonstrates that our solution outperforms CV with 10% in a highly dynamic IoT environments, with the ability to detect and mitigate unreliable sensors.","Title: Automated Feature Extraction for Website Fingerprinting through Deep Learning.\nYear: 2017\n\nAbstract: Several studies have shown that the network traffic that is generated by a visit to a website over Tor reveals information specific to the website through the timing and sizes of network packets. By capturing traffic traces between users and their Tor entry guard, a network eavesdropper can leverage this meta-data to reveal which website Tor users are visiting. The success of such attacks heavily depends on the particular set of traffic features that are used to construct the fingerprint. Typically, these features are manually engineered and, as such, any change introduced to the Tor network can render these carefully constructed features ineffective. In this paper, we show that an adversary can automate the feature engineering process, and thus automatically deanonymize Tor traffic by applying our novel method based on deep learning. We evaluate our approach on a dataset comprised of more than three million network traces, which is the largest dataset of web traffic ever gathered for website fingerprinting, and find that the performance achieved by deep learning techniques is comparable to known approaches which include various research efforts spanning over multiple years. Furthermore, it eliminates the need for feature design and selection which is a tedious work and has been one of the main focus of prior work. We conclude that the ability to automatically construct the most relevant traffic features and perform accurate traffic recognition makes our deep learning based approach an efficient, flexible and robust technique for website fingerprinting.","Title: Trustworthy Data-Driven Networked Production For Customer-Centric Plants\nYear: 2017\n\nAbstract: Purpose - Industry 4.0 envisions a future of networked production where interconnected machines and business processes running in the cloud will communicate with one another to optimize production and enable more efficient and sustainable individualized/mass manufacturing. However, the openness and process transparency of networked production in hyperconnected manufacturing enterprises pose severe cyber-security threats and information security challenges that need to be dealt with. The paper aims to discuss these issues.Design/methodology/approach - This paper presents a distributed trust model and middleware for collaborative and decentralized access control to guarantee data transparency, integrity, authenticity and authorization of dataflow-oriented Industry 4.0 processes.Findings - The results of a performance study indicate that private blockchains are capable of securing IoT-enabled dataflow-oriented networked production processes across the trust boundaries of the Industry 4.0 manufacturing enterprise.Originality/value - This paper contributes a decentralized identity and relationship management for users, sensors, actuators, gateways and cloud services to support processes that cross the trust boundaries of the manufacturing enterprise, while offering protection against malicious adversaries gaining unauthorized access to systems, services and information.","Title: Access Control with Delegated Authorization Policy Evaluation for Data-Driven Microservice Workflows.\nYear: 2017\n\nAbstract: Microservices offer a compelling competitive advantage for building data flow systems as a choreography of self-contained data endpoints that each implement a specific data processing functionality. Such a 'single responsibility principle' design makes them well suited for constructing scalable and flexible data integration and real-time data flow applications. In this paper, we investigate microservice based data processing workflows from a security point of view, i.e., (1) how to constrain data processing workflows with respect to dynamic authorization policies granting or denying access to certain microservice results depending on the flow of the data; (2) how to let multiple microservices contribute to a collective data-driven authorization decision and (3) how to put adequate measures in place such that the data within each individual microservice is protected against illegitimate access from unauthorized users or other microservices. Due to this multifold objective, enforcing access control on the data endpoints to prevent information leakage or preserve one's privacy becomes far more challenging, as authorization policies can have dependencies and decision outcomes cross-cutting data in multiple microservices. To address this challenge, we present and evaluate a workflow-oriented authorization framework that enforces authorization policies in a decentralized manner and where the delegated policy evaluation leverages feature toggles that are managed at runtime by software circuit breakers to secure the distributed data processing workflows. The benefit of our solution is that, on the one hand, authorization policies restrict access to the data endpoints of the microservices, and on the other hand, microservices can safely rely on other data endpoints to collectively evaluate cross-cutting access control decisions without having to rely on a shared storage backend holding all the necessary information for the policy evaluation.","Title: Privacy-Preserving Behavioral Authentication on Smartphones.\nYear: 2017\n\nAbstract: User behavior analytics is playing a growing role in security decisions that grant or deny access to online services. Smartphone sensors can enhance PIN and pattern based mobile authentication by continuously monitoring user behavior. However, these schemes pose a privacy risk when sensitive data is disclosed to online service providers who desire to continuously assess the risk. In this paper we enhance behavioral authentication based on keystroke dynamics with privacy. To prevent service providers from reconstructing the original text typed by consumers, we implement and evaluate 3 privacy-preserving techniques: permutation, substitution and suppression. Applying the permutation technique leads to no measurable change in Equal Error Rate (EER). Thus, the EER while using permutation is the same as when no privacy preserving techniques are used, i.e. 16% for the 'user classification' and 18% for 'user clustering'. Adopting substitution, leads to an absolute increase in EER of 15% for the first task, and 11% for the second one, which gives a total of 31% and 39% respectively. For the suppression technique, the EER increases linearly with the number of keystrokes suppressed.","Title: Frictionless Authentication Systems: Emerging Trends, Research Challenges and Opportunities.\nYear: 2018\n\nAbstract: Authentication and authorization are critical security layers to protect a wide range of online systems, services and content. However, the increased prevalence of wearable and mobile devices, the expectations of a frictionless experience and the diverse user environments will challenge the way users are authenticated. Consumers demand secure and privacy-aware access from any device, whenever and wherever they are, without any obstacles. This paper reviews emerging trends and challenges with frictionless authentication systems and identifies opportunities for further research related to the enrollment of users, the usability of authentication schemes, as well as security and privacy trade-offs of mobile and wearable continuous authentication systems.","Title: Policy reconciliation for access control in dynamic cross-enterprise collaborations.\nYear: 2018\n\nAbstract: In dynamic cross-enterprise collaborations, different enterprises form a - possibly temporary - business relationship. To integrate their business processes, enterprises may need to grant each other limited access to their information systems. Authentication and authorization are key to secure information handling. However, access control policies often rely on non-standardized attributes to describe the roles and permissions of their employees which convolutes cross-organizational authorization when business relationships evolve quickly. Our framework addresses the managerial overhead of continuous updates to access control policies for enterprise information systems to accommodate disparate attribute usage. By inferring attribute relationships, our framework facilitates attribute and policy reconciliation, and automatically aligns dynamic entitlements during the evaluation of authorization decisions. We validate our framework with a Industry 4.0 motivating scenario on networked production where such dynamic cross-enterprise collaborations are quintessential. The evaluation reveals the capabilities and performance of our framework, and illustrates the feasibility of liberating the security administrator from manually provisioning and aligning attributes, and verifying the consistency of access control policies for cross-enterprise collaborations.","Title: K8-Scalar: a workbench to compare autoscalers for container-orchestrated services (Artifact).\nYear: 2018\n\nAbstract: This artifact is an easy-to-use and extensible workbench exemplar, named K8-Scalar, which allows researchers to implement and evaluate different self-adaptive approaches to autoscaling container-orchestrated services. The workbench is based on Docker, a popular technology for easing the deployment of containerized software that also has been positioned as an enabler for reproducible research. The workbench also relies on a container orchestration framework: Kubernetes (K8s), the de-facto industry standard for orchestration and monitoring of elastically scalable container-based services. Finally, it integrates and extends Scalar, a generic testbed for evaluating the scalability of large-scale systems with support for evaluating the performance of autoscalers for database clusters. \r\n\r\nThe associated scholarly paper presents (i) the architecture and implementation of K8-Scalar and how a particular autoscaler can be plugged in, (ii) sketches the design of a Riemann-based autoscaler for database clusters, (iii) illustrates how to design, setup and analyze a series of experiments to configure and evaluate the performance of this autoscaler for a particular database (i.e., Cassandra) and a particular workload type, (iv) and validates the effectiveness of K8-scalar as a workbench for accurately comparing the performance of different auto-scaling strategies. Future work includes extending K8-Scalar with an improved research data management repository.","Title: Automated Website Fingerprinting through Deep Learning.\nYear: 2018\n\nAbstract: Several studies have shown that the network traffic that is generated by a visit to a website over Tor reveals information specific to the website through the timing and sizes of network packets. By capturing traffic traces between users and their Tor entry guard, a network eavesdropper can leverage this meta-data to reveal which website Tor users are visiting. The success of such attacks heavily depends on the particular set of traffic features that are used to construct the fingerprint. Typically, these features are manually engineered and, as such, any change introduced to the Tor network can render these carefully constructed features ineffective. In this paper, we show that an adversary can automate the feature engineering process, and thus automatically deanonymize Tor traffic by applying our novel method based on deep learning. We collect a dataset comprised of more than three million network traces, which is the largest dataset of web traffic ever used for website fingerprinting, and find that the performance achieved by our deep learning approaches is comparable to known methods which include various research efforts spanning over multiple years. The obtained success rate exceeds 96% for a closed world of 100 websites and 94% for our biggest closed world of 900 classes. In our open world evaluation, the most performant deep learning model is 2% more accurate than the state-of-the-art attack. Furthermore, we show that the implicit features automatically learned by our approach are far more resilient to dynamic changes of web content over time. We conclude that the ability to automatically construct the most relevant traffic features and perform accurate traffic recognition makes our deep learning based approach an efficient, flexible and robust technique for website fingerprinting.","Title: Semantic analysis and verification of context-driven adaptive applications in intelligent environments.\nYear: 2016\n\nAbstract: With the advent of the Internet of Things (IoT) and Cyber-Physical Systems (CPS), assistive applications and smart environments can tap into a growing amount of context information to learn about their users, their surroundings and typical behavior. This information is useful to adapt intelligently, autonomously and non-intrusively to a myriad of circumstances. However, trustworthiness and reliable adaptation to changes in line with user expectations—especially to situations that the developers did not anticipate—remain key concerns. Understanding the impact of changes from a developer (design time) and system (runtime) perspective, and ensuring that no undesired side effects take place are two non-trivial research challenges to increase the adoption of such applications. Given the limited tool support for anticipating change at design time and runtime, we present our change impact analysis (CIA) methodology—found in the formal semantic modeling of intelligent environments and rule-based application behavior—to contribute to the development and deployment of reliable context-aware adaptive applications. We validate our contributions on non-trivial smart home and office scenarios, and demonstrate how our framework helps increase trust in intelligent environment applications by anticipating change implications upfront at design time and by minimizing the occurrence of undesired side effects at runtime.","Title: Robust Digital Twin Compositions for Industry 4.0 Smart Manufacturing Systems\nYear: 2018\n\nAbstract: Industry 4.0 is an emerging business paradigm that is reaping the benefits of enabling technologies driving intelligent systems and environments. By acquiring, processing and acting upon various kinds of relevant context information, smart automated manufacturing systems can make well-informed decisions to adapt and optimize their production processes at runtime. To manage this complexity, the manufacturing world is proposing the 'Digital Twin' model to represent physical products in the real space and their virtual counterparts in the virtual space, with data connections to tie the virtual and real products together for an augmented view of the manufacturing workflow. The benefits of such representations are simplified process simulations and efficiency optimizations, predictions, early warnings, etc. However, the robustness and fidelity of digital twins are a critical concern, especially when independently developed production systems and corresponding digital twins interfere with one another in a manufacturing workflow and jeopardize the proper behavior of production systems. We therefore evaluate the addition of safeguards to digital twins for smart cyber-physical production systems (CPPS) in an Industry 4.0 manufacturing workflow in the form of feature toggles that are managed at runtime by software circuit breakers. Our evaluation shows how these improvements can increase the robustness of interacting digital twins by avoiding local errors from cascading through the distributed production or manufacturing workflow.","Title: Gait template protection using HMM-UBM\nYear: 2018\n\nAbstract: This paper presents a hidden Markov model-Universal background model gait authentication system, which is also incorporated into a template protection based on a fuzzy commitment scheme. We show that with limited enrollment data the HMM-UBM system achieves a very competitive equal error rate of ≈1% using one sensor. The proposed template protection scheme benefits from eigen-features coming from multiple Universal background model systems fused with a novel technique that minimizes the bit error rate for genuine attempts. This allows the protected system to achieve a false rejection rate below 5% with an effective key length of 64 bits.","Title: Internet of Things for enabling smart environments: A technology-centric perspective.\nYear: 2019\n\nAbstract: The Internet of Things (IoT) is a computing paradigm whereby everyday life objects are augmented with computational and wireless communication capabilities, typically through the incorporation of resource-constrained devices including sensors and actuators, which enable their connection to the Internet. The IoT is seen as the key ingredient for the development of smart environments. Nevertheless, the current IoT ecosystem offers many alternative communication solutions with diverse performance characteristics. This situation presents a major challenge to identifying the most suitable IoT communication solution(s) for a particular smart environment. In this paper we consider the distinct requirements of key smart environments, namely the smart home, smart health, smart cities and smart factories, and relate them to current IoT communication solutions. Specifically, we describe the core characteristics of these smart environments and then proceed to provide a comprehensive survey of relevant IoT communication technologies and architectures. We conclude with our reflections on the crucial features of IoT solutions in this setting and a discussion of challenges that remain open for research.","Title: Managing distributed trust relationships for multi-modal authentication.\nYear: 2018\n\nAbstract: Multi-modal active authentication schemes fuse decisions of multiple behavioral biometrics (behaviometrics) to reduce identity verification errors. The challenge that we address in this work is the security risk caused by these decision fusion schemes making invalid assumptions, such as a fixed probability of (in)correct recognition and a temporal congruence of behaviometrics. To mitigate this risk, this paper presents a formal trust model that drives the behaviometric selection and composition. Our trust model adopts a hybrid approach combining policy and reputation based knowledge representation techniques. Our model and framework (1) externalizes trust knowledge from the authentication logic to achieve loosely coupled trust management, and (2) formalizes this knowledge in description logic to reason upon and broker complex distributed trust relationships to make risk-adaptive decisions for multi-modal authentication. The evaluation of our proof-of-concept illustrates an acceptable performance overhead while lifting the burden of manual trust and behaviometric management for multi-modal authentication.","Title: Detection of algorithmically generated domain names used by botnets - a dual arms race.\nYear: 2019\n\nAbstract: Malware typically uses Domain Generation Algorithms (DGAs) as a mechanism to contact their Command and Control server. In recent years, different approaches to automatically detect generated domain names have been proposed, based on machine learning. The first problem that we address is the difficulty to systematically compare these DGA detection algorithms due to the lack of an independent benchmark. The second problem that we investigate is the difficulty for an adversary to circumvent these classifiers when the machine learning models backing these DGA-detectors are known. In this paper we compare two different approaches on the same set of DGAs: classical machine learning using manually engineered features and a 'deep learning' recurrent neural network. We show that the deep learning approach performs consistently better on all of the tested DGAs, with an average classification accuracy of 98.7% versus 93.8% for the manually engineered features. We also show that one of the dangers of manual feature engineering is that DGAs can adapt their strategy, based on knowledge of the features used to detect them. To demonstrate this, we use the knowledge of the used feature set to design a new DGA which makes the random forest classifier powerless with a classification accuracy of 59.9%. The deep learning classifier is also (albeit less) affected, reducing its accuracy to 85.5%.","Title: Special Issue: Big Data for context-aware applications and intelligent environments\nYear: 2019\n\nAbstract: Disruptive paradigm shifts such as the Internet of Things (IoT) and Cyber–Physical Systems (CPS) are creating a wealth of streaming context information. Large-scale context-awareness combining IoT and Big Data drive the creation of smarter application ecosystems in diverse vertical domains, including smart health, finance, smart grids and cities, transportation, Industry 4.0, etc. This special issue addresses core topics on the design, the use and the evaluation of Big Data enabling technologies to build next-generation context-aware applications and computing systems for future intelligent environments.","Title: A Systematic Comparison of Age and Gender Prediction on IMU Sensor-Based Gait Traces.\nYear: 2019\n\nAbstract: Sensors provide the foundation of many smart applications and cyber-physical systems by measuring and processing information upon which applications can make intelligent decisions or inform their users. Inertial measurement unit (IMU) sensors-and accelerometers and gyroscopes in particular-are readily available on contemporary smartphones and wearable devices. They have been widely adopted in the area of activity recognition, with fall detection and step counting applications being prominent examples in this field. However, these sensors may also incidentally reveal sensitive information in a way that is not easily envisioned upfront by developers. Far worse, the leakage of sensitive information to third parties, such as recommender systems or targeted advertising applications, may cause privacy concerns for unsuspecting end-users. In this paper, we explore the elicitation of age and gender information from gait traces obtained from IMU sensors, and systematically compare different feature engineering and machine learning algorithms, including both traditional and deep learning methods. We describe in detail the prediction methods that our team used in the OU-ISIR Wearable Sensor-based Gait Challenge: Age and Gender (GAG 2019) at the 12th IAPR International Conference on Biometrics. In these two competitions, our team obtained the best solutions amongst all international participants, and this for both the age and gender predictions. Our research shows that it is feasible to predict age and gender with a reasonable accuracy on gait traces of just a few seconds. Furthermore, it illustrates the need to put in place adequate measures in order to mitigate unintended information leakage by abusing sensors as an unanticipated side channel for sensitive information or private traits.","Title: AuthGuide: Analyzing Security, Privacy and Usability Trade-Offs in Multi-factor Authentication\nYear: 2021\n\nAbstract: Multi-factor authentication (MFA) reduces the risk of compromised credentials. However, selecting, configuring and combining different authentication factors is a challenge for both security administrators and end-users, as the configuration possibilities are large and the implications of choices on security, privacy and usability are not always well understood. This concern is further aggravated when the security administrator grants the end-user some flexibility for the selection of authentication factors, or when the latter are combined in a risk-adaptive manner. In this work, we present AUTHGUIDE, an authentication knowledge and configuration framework that increases the awareness about these trade-offs. Additionally, it raises the level of abstraction to configure MFA for a given identity and access management (IAM) platform through a series of questions by mapping the responses onto the IAM's workflow of authentication steps for registration and login. We implemented AUTHGUIDE, validated it on top of the open source Keycloak IAM, and evaluated the effectiveness of our framework to analyze the security, privacy and usability trade-offs.","Title: On the Security of Biometrics and Fuzzy Commitment Cryptosystems: A Study on Gait Authentication\nYear: 2021\n\nAbstract: As biometric templates consist of highly correlated features, the real security level offered by biometric authentication systems remains an open research question. In this work we provide new approximations and a lower bound of the security offered by fuzzy commitment schemes. Fuzzy commitment cryptosystems and in general biometric template protection schemes play an important role in allowing for remote storage and processing of biometric data, as they mitigate the threat of biometric template leakage. The use of such schemes would alleviate some of the usability constraints imposed by the state-of-practice local use of biometrics. As such we conduct an in-depth security analysis for IMU based gait authentication systems, where we evaluate the effectiveness of attacks within the scope of two well-defined threat models that target both unprotected and protected systems. A pivotal enabler of our analysis is the development of nine different approaches to gait authentication, which allows us to perform intramodal fusion on these distinct, yet highly correlated biometric templates, and to protect them with a strengthened fuzzy commitment scheme. Our analysis clearly demonstrates the high correlation between the different biometric templates, which, among others, further showcases the threat of biometric template leakage. Furthermore, as our analysis incorporates a threat model that assumes biometric template leakage, it provides metrics for the security provided by the biometric modality itself.","Title: Applying Machine Learning to use security oracles: a case study in virus and malware detection\nYear: 2022\n\nAbstract: Machine Learning (ML) has a significant potential to enhance the security posture of an organization by improving threat detection and discovery. The growing quality and quantity of data through measurements creates opportunities in this context. However, when an organization does not have sufficient labeled data to make predictions, it can rely on third parties for expert advise. In this work, we present a real-world case study of a company offering security services to other businesses on top of its portfolio of internal security assets. The security provider adopts ML to learn when to cost-effectively invoke a third party service/oracle (i.e. VirusTotal), first to boost its own detection rate in order to protect its customers, and second to obtain new ground truth to further optimize its future oracle use, all under fixed query budget constraints. While the decision making of the ML system was very successful in terms of avoiding false positives and false negatives, we nonetheless identified several security challenges when adopting ML for a cost-effective use of security oracles. We evaluate our ML solution on real data, elicit various lessons learned about the increased attack surface when using ML in security applications, and identify countermeasures to secure this ML pipeline.","Title: Captcha me if you can: Imitation Games with Reinforcement Learning\nYear: 2022\n\nAbstract: Since their inception, Captchas have been widely used as reverse Turing tests for combating bot proliferation on the web. This has resulted in an arms race between bot developers that automate Captcha solvers and Captcha services that adjust the challenges accordingly or come up with new ones altogether. Ultimately, older generations could be bypassed consistently, and thus in the third version of reCAPTCHA, Google offers zero user friction. The intent in the new system is not only to avoid interrupting user experience but to also obfuscate the nature of the challenge itself, being much less prominent than a text or image recognition task. We introduce a methodology that learns through interaction how to evade detection, while collecting and analyzing reCAPTCHA v3 scores over fifteen months and various web environments. With reinforcement learning as the backbone, we build models that can simulate human-like web browsing behaviour by using the returned score as an informative signal. Our study exposes an important vulnerability: while the score is influenced by a multitude of undisclosed factors, it is easily accessible and it enables adversaries to learn and perfect evasive models. Notably, we demonstrate that our automation models, which integrate general web browsing capabilities, transfer between websites with an evasion rate up to 99.6%."],"string":"[\n \"Title: Formal modelling, knowledge representation and reasoning for design and development of user-centric pervasive software: a meta-review\\nYear: 2011\\n\\nAbstract: Increasing demand for large scale and highly complex systems and applications, particularly with the emergence of pervasive computing and the impact of adaptive systems, introduces significant challenges for software development, as well as for user-machine interaction. Therefore, a perspective shift on software development and user-machine interaction is required. An amalgamation of model driven development and ontologies has been envisaged as a promising direction in recent literature. In this paper, we investigate this merged approach and conclude that a merger of both approaches, from formal modelling and knowledge representation perspective, on the one hand enables use of ontologies at run-time together with rules, prominently in terms of run-time reasoning, dynamic adaptations, software intelligibility, self-expressiveness, user involvement, and user situation awareness; and on the other hand at development time, prominently in terms of automated and incremental code generation, requirement adaptability, preservation of application knowledge, and validation and verification of structural and behavioural properties of the software. The core contribution of this paper lies in providing an elaborate and exploratory discussion of the problem and solution spaces along with a multidisciplinary meta-review and identification of complementary efforts in literature required to realise a merged approach.\",\n \"Title: A reconfigurable component model with semantic type system for dynamic WSN applications.\\nYear: 2012\\n\\nAbstract: Runtime reconfigurable component models provide several attractions with regard to the management of wireless sensor network (WSN) applications operating in dynamic environments and under evolving application requirements. One such attraction is the runtime discovery of suitable components for reuse in changing application compositions. Syntactic interface typing, provided by contemporary component models, however only supports exact interface matching. This causes limited reuse of components and complicates management of WSN applications. We argue that more flexibility is required to efficiently manage the complex, large-scale and dynamic WSN deployments of the future. In this paper, we describe the addition of semantic service descriptions to component interfaces to support compatibility and subtype testing. This allows rich discovery and reuse of third-party functionality and reasoning at the level of equivalent service types. We report on the incorporation of these semantic interface definitions in the Loosely Coupled Component Infrastructure (LooCI). Evaluation thereof shows that the scheme imposes minimal computational and memory overhead, while significantly reducing the complexity and cost of reconfiguration.\",\n \"Title: Mobile phones assisting with health self-care: a diabetes case study\\nYear: 2008\\n\\nAbstract: The applicability of pervasive and mobile computing in the health care sector is beyond dispute. This paper explores the use of the mobile phone as a tool for personalized health care assistance for individuals diagnosed with diabetes. By monitoring user location and activity on the mobile phone, recognizing past behavior and augmenting the logging of blood glucose levels with context data, our prototype application assists with taking well-informed decisions on daily drug dosage to achieve and maintain stable blood glucose levels. Evaluation of the prototype application indicate that a brief training of the application suffices to capture patterns in the user's relevant context that simplify glucose level trends analysis. We describe some of the details of the user study and the prototype application, and conclude with plans to investigate context-driven activity prediction to further improve the decision support for the user.\",\n \"Title: Memory and communication driven spatio-temporal scheduling on MPSoCs\\nYear: 2012\\n\\nAbstract: Scheduling and executing software efficiently on contemporary embedded systems, featuring heterogeneous multi-processors, multiple power modes, complex memory hierarchies and advanced interconnects, is a daunting task. State-of-the-art tools that schedule software tasks to hardware resources face limitations: (1) either they do not take into account the interdependancies among processing, memory and communication constraints (2) or they decouple the problem of spatial assignment from temporal scheduling. As a result existing tools make sub-optimal spatio-temporal scheduling decisions. This paper presents a technique to find globally optimized solutions by co-exploring spatio-temporal schedules for computation, data storage and communication simultaneously, considering the interdependencies between them. Experiments on mapping exploration of an image processing application on a heterogeneous MPSoC platform show that this co-exploration methodology finds schedules that are more energy efficient, when compared to decoupled exploration techniques for the particular application and target platform.\",\n \"Title: Modeling Human Actors in an Intelligent Automated Warehouse\\nYear: 2009\\n\\nAbstract: Warehouse automation has progressed at a rapid pace over the last decade. While the tendency has been to implement fully automated solutions, most warehouses today exist as a mixture of manually operated and fully automated material handling sections. In such a hybrid warehouse, men and machines move around goods in between sections in order to retrieve, transport and stack goods according to their nature and quantity. The biggest challenge in hybrid warehouses is to optimize the alignment of manual and automatic processes in order to improve the flow of materials between storage areas and distribution centers. Integrating individuals as human actors in an automation solution is not straightforward due to unpredictable human behavior. In this paper, we will investigate how we can model the characteristics of human actors within an automation solution and how software systems can unify human actors with automated business processes to coordinate both as first class entities for logistics activities within a hybrid warehouse.\",\n \"Title: Teamwork on the Road: Efficient Collaboration in VANETs with Context-based Grouping.\\nYear: 2011\\n\\nAbstract: There is an emerging trend nowadays for vehicles to be equipped with an embedded on-board computing unit with communication capabilities to enhance the overall driving experience. Such a system enables vehicle-to-vehicle and vehicle-to-infrastructure communication and provides vehicles with up-to-date route and traffic information. However, as this information is not relevant for all vehicles, context-aware communication is considered to be vital for more intelligent inter-vehicular communication. Traditional network addressing schemes are not well suited because they do not take into account contextual properties such as location, direction, speed, time and information interest for group-based communication in large scale vehicular networks. The conventional network paradigms of multicasting and broadcasting to define groups cause too much overhead. First, there is no way to optimize network traffic based on the contextual characteristics of the nodes. Second, they do not take into account the mobility patterns of the vehicles and the road layouts. We propose a context-based grouping mechanism in which only relevant information is shared among the vehicles in a group. We evaluate our approach by formulating groups based on common spatialtemporal characteristics and shared interests. The simulated experiments show that by inducing our context-based grouping mechanism we can significantly reduce the irrelevant/redundant information flows and the overall network traffic usage.\",\n \"Title: Geo-social interaction: context-aware help in large scale public spaces\\nYear: 2010\\n\\nAbstract: We present an approach to exploit social and spatio-temporal context in order to improve information dissemination in dynamic large-scale public spaces. We illustrate it by applying a proposed measure of geo-social relevance of each individual in a simulated vehicular network and by comparing the performance of different network message passing techniques in an inter-vehicle 'help-me-best-and-do-it-fast' communication scenario. We conclude that the use of social networking capabilities of an individual combined with knowledge about their spatio-temporal context information significantly improves purposeful interaction between individuals in terms of both the efficiency of the network data dissemination and the quality of the delivered information.\",\n \"Title: Context-driven migration and diffusion of pervasive services on the OSGi framework\\nYear: 2010\\n\\nAbstract: The ubiquity of wireless ad hoc networks and the benefits of loosely coupled services have fostered a growing interest in service-oriented architectures for pervasive computing. Context-aware services and runtime adaptation are key to expedite human interaction with dynamic pervasive computing environments. We explore two types of live service mobility to avoid service disruptions in mobile ad hoc networks. Service migration moves a service at runtime from one host to another including its state, while service diffusion replicates the service and the state on multiple hosts. We analyse the basic requirements for service mobility and evaluate our OSGi-based implementation for service mobility with real life experiments. Our results show that the overhead of state transfer and synchronisation is limited for relatively small applications and that the delay for handing over to a replicated service in a small scale network with enforced network failures remains minimal.\",\n \"Title: An Intelligent Domotics System to Automate User Actions\\nYear: 2010\\n\\nAbstract: Home automation systems are ambient intelligence systems that are designed to help people proactively, but sensibly. In this paper we propose a system that learns and automates patterns in the interactions of the user with the home automation devices. We will show our approach and architecture. We use an event processing tool to handle the events from the home automation devices, prediction algorithms to predict the next action and reinforcement learning to decide which action are suitable to be automated.\",\n \"Title: Context-aware optimized information dissemination in large scale vehicular networks\\nYear: 2010\\n\\nAbstract: Context-aware inter-vehicular communication is considered to be vital for inducing intelligence through the use of embedded computing devices inside vehicles. Vehicles in a scalable environment may disseminate information about certain road traffic conditions, traffic incidents, free parking space or other relevant information to the neighboring vehicles in the vicinity. In this paper, we optimize the dissemination of such context information by predicting traffic patterns in a geographical region, including traffic hotspots. We optimized the relevance backpropagation algorithm with prediction capabilities to efficiently disseminate information. We evaluate our approach with the OMNET++ network simulator using realistic large scale data sets. Our experimental results show that by optimizing information dissemination we significantly improve the Network Traffic, availability and relevant information delivery in a large scale vehicular network.\",\n \"Title: The Future of Mobile E-health Application Development: Exploring HTML5 for Context-aware Diabetes Monitoring.\\nYear: 2013\\n\\nAbstract: According to predictions of information technology research and advisory firms, such as Gartner, hybrid HTML5 appli- cations will be the future for mobile application development. In this paper, we explore the feasibility of using HTML5 and related web application standards for the development of mobile e-health applications, using a diabetes monitoring application as a practical use case. Context-awareness and visualizing multivariate data with parallel coordinates for decision support are key features of this mobile e-health application. We compare the strengths and weaknesses of the hybrid HTML5 approach with native mobile applications, and report on practical experiences with the development and usage of the application. Our experiments show that developers of fairly advanced context-aware mobile applications can definitely benefit from the HTML5 application portability across different mobile platforms. However, compared to native applications, they should be aware of missing features such as secure storage, non-negligible performance penalties of JavaScript business logic on a mobile platform, and an inferior user experience.\",\n \"Title: Comparative Evaluation of Converged Service-Oriented Architectures\\nYear: 2007\\n\\nAbstract: In this paper we evaluate and compare five commercial off-the-shelf platforms for building converged service-oriented architectures in an ambient computing environment. To this end, we have identified several categories of requirements that support the always-connected digital lifestyle of the mobile user. Key requirements are providing convergence -- joining the worlds of web services and telecom services -- and offering context awareness in order to tailor services better to the user's environment, preferences and needs. Our evaluation shows that currently none of the investigated architectures completely fulfills the two aforementioned requirements in order to deploy a variety of future converged mobile and context-aware services. However, the resulting comparison can be used as a practical guideline for decision-makers to select a platform to build a service-oriented architecture adjusted to the specific requirements within their application domain.\",\n \"Title: Adaptive context management using a component-based approach\\nYear: 2005\\n\\nAbstract: Context-awareness has become a necessity for adaptable intelligent applications and services. It is crucial for ubiquitous and pervasive computing because the context of a user or device serves as the source of information to adapt services. In this paper, we propose a modular context management system that is able to collect, transform, reason on and use context information to adapt services. By employing a component-based approach, we enable our infrastructure not only to support context-aware adaptation of services, but also to support adaptation of the context management system itself at deployment time and at runtime. This self-adaptation is based upon the service requirements and the current context of the device, such as the current resource usage or other devices in the neighborhood, resulting in an adaptive context management system for improved quality of service.\",\n \"Title: Semantic and syntactic modeling of component-based services for context-aware pervasive systems using OWL-s\\nYear: 2005\\n\\nAbstract: http://www.cs.kuleuven.ac.be Abstract. In this paper, we present a service design methodology and specification as a basis for a pervasive context-aware service infrastruc- ture. The service specification is based on the OWL-s specification, a standard proposed to add a semantic layer on top of WSDL web ser- vice descriptions. We have defined a set of OWL-s concepts that make it possible to express various pervasive service related properties, including service adaptation, relocation, personalization, deployment and runtime requirements. Though not straightforward to parse within strict resource boundaries, OWL-s provides an open, flexible specification language for expressing syntactic and semantic pervasive service characteristics and it increases service interoperability.\",\n \"Title: Towards context-aware and resource-driven self-adaptation for mobile handheld applications\\nYear: 2007\\n\\nAbstract: Mobile handheld computing is gaining momentum as more and more wireless handheld devices are being used to accomplish various computing tasks. Context-awareness can help to adapt and personalize applications or to optimize resource usage. However, many existing context infrastructures by themselves impose heavy resource requirements for deployment or highly affect the limited autonomy of the mobile device. In this paper we describe how resource-driven self-adaptation is used in our layered context-driven application middleware in order to enable deployment on a mobile device and optimize resource usage. Our evaluation shows that the introspection and intercession capabilities of the self-adapting middleware provide the necessary flexibility to achieve a balanced resource usage between the context-driven application middleware and the context-aware applications, and that the resource-driven self-adaptation is able to more than double the battery lifetime in real life scenarios.\",\n \"Title: Pervasive Services on the Move: Smart Service Diffusion on the OSGi Framework\\nYear: 2008\\n\\nAbstract: The ubiquity of wireless ad hoc networks and the benefits of loosely coupled services have fostered a growing interest in service oriented architectures for mobile and pervasive computing. Many architectures have been proposed that implement context-sensitive service discovery, selection and composition, or that use a component-based software engineering methodology to facilitate runtime adaptation to changing circumstances. This paper explores live service mobility in pervasive computing environments as a way to mitigate the risk of disconnections during service provision in mobile ad hoc networks. It focuses on context-aware service migration and diffusion to multiple hosts to increase accessibility and expedite human interaction with the service. We analyze the basic requirements for service mobility and discuss an implementation on top of OSGi. Finally, we evaluate our approach to service mobility and illustrate its effectiveness by means of a real-life scenario.\",\n \"Title: Architectural backpropagation support for managing ambiguous context in smart environments\\nYear: 2007\\n\\nAbstract: The evolution to ubiquitous information and communication networks is evident. Technology is emerging that connects everyday objects and embeds intelligence in our environment. In the Internet of Things, smart objects collect context information from various sources to turn a static environment into a smart and proactive one. Managing the ambiguous nature of context information will be crucial to select relevant information for the tasks at hand. In this paper we present a vector space model that uses context quality parameters to manage context ambiguity and to identity irrelevant context providers. We also discuss backpropagation applied in the network architecture to filter unused context information in the network as close to the source as possible. Experiments show that our contribution not only reduces the amount of useless information a smart object deals with, but also the distribution of unused context information throughout the network architecture.\",\n \"Title: Towards an Extensible Context Ontology for Ambient Intelligence\\nYear: 2004\\n\\nAbstract: To realise an Ambient Intelligence environment, it is paramount that applications can dispose of information about the context in which they operate, preferably in a very general manner. For this purpose various types of information should be assembled to form a representation of the context of the device on which aforementioned applications run. To allow interoperability in an Ambient Intelligence environment, it is necessary that the context terminology is commonly understood by all participating devices. In this paper we propose an adaptable and extensible context ontology for creating context-awaxe computing infrastructures, ranging from small embedded devices to high-end service platforms. The ontology has been designed to solve several key challenges in Ambient Intelligence, such as application adaptation, automatic code generation and code mobility, and generation of device specific user interfaces.\",\n \"Title: Suitability Of Existing Service Discovery Protocols For Mobile Users In An Ambient Intelligence Environment\\nYear: 2004\\n\\nAbstract: Service discovery enables users to access information, resources and services anytime, anywhere. This involves a client, a service provider and an infrastructure for service registration and lookup. Clients use service discovery protocols (SDPs) to issue a service request to a service registry or an individual service provider. In this paper we investigate the suitability of existing SDPs for mobile users in an ambient intelligence context. After reviewing the most well-known SDPs, common problems in the domain of user mobility and solutions that are currently available are discussed.\",\n \"Title: A Loosely Coupled and Distributed Bayesian Framework for Multi-context Recognition in Dynamic Ubiquitous Environments\\nYear: 2013\\n\\nAbstract: Today's ubiquitous environments are characterized by smart applications with variable context requirements on the one hand and a dynamic availability of heterogeneous sensors on the other hand. Currently, many existing systems pursue a structured ad-hoc approach with rigid mappings between the applications and the context sources, adversely affecting the performance of these applications when the availability of the context sources drops. Furthermore, such ad-hoc and tightly coupled approaches suffer from reduced flexibility when simultaneously handling multiple smart applications in dynamic environments characterized by a high sensor churn rate. We present a loosely coupled Bayesian-based learning framework that addresses these challenges by allowing dynamic many to many relations between smart applications and context sources with support for recognizing diverse contexts more reliably in the presence of disappearing sensors. Our approach is able to lift these limitations by leveraging the availability of multiple co occurring contexts and their conditional dependencies. On the one hand, the framework exhibits flexibility to dynamically add and remove contexts through autonomic learning of individual contexts appropriate for the spatially distributed ubiquitous infrastructures. On the other hand, it incorporates the advantages of multi-view learning by boot-strapping and fusing multiple heterogeneous context information streams. Our experimental evaluation using a personal assistant application demonstrates the performance and robustness of the proposed framework with significant adaptability and resilience to missing data and partial observability.\",\n \"Title: The Right Thing to Do: Automating Support for Assisted Living with Dynamic Decision Networks\\nYear: 2013\\n\\nAbstract: In an era where ubiquitous systems will be mainstream, users will take a more passive role and these systems will have to make smart decisions on behalf of their users. Automating these decisions in a continuously evolving dynamic context can be challenging. First of all, the right thing to do usually depends on the circumstances and context at hand. What might be a good decision today, could be a bad one tomorrow. Secondly, the system should be made aware of the impact of its decisions over time so that it can learn from its mistakes as humans do. In this paper, we formulate a technique for decision support systems to mitigate runtime uncertainty in the observed context, and demonstrate our context-driven probabilistic framework for ubiquitous systems that addresses the above mentioned challenges. Our framework incorporates end-to-end Quality of Context (QoC) as a key ingredient to make well-informed decisions. It leverages Dynamic Decision Networks (DDN) to deal with the presence of uncertainty and the partial observability of context information, as well as the temporal effects of the decisions. Our experiments with the framework demonstrate the feasibility of our approach and potential benefits to automatically make the best decision in the presence of a changing environment.\",\n \"Title: Architectural styles for opportunistic mobile communication: requirements and design patterns\\nYear: 2008\\n\\nAbstract: Mobile computing has been in the research epicenter for several decades. We have seen drastic shifts with mobile computing systems and wireless ad hoc networks dynamically adapting to create co-operating nodes that provide the right services at the right time. One aspect of such systems that has been poorly addressed is the complexity of developing applications for mobile users that require group interactions in large scale networks, especially between people unfamiliar with one another but with similar goals. Such systems need to know the type of social interaction, the context of all participants and nodes in the network, and a proper architectural design to implement scalability up to city wide networks. In this paper, we analyze which architectural styles and design patterns are the best suited the implement the various interaction requirements. We address scalability for interactions in large-scale networks from a software architectural perspective and focus on event-driven service oriented architectures to make the design of context-aware systems for large-scale mobile interactions a less complex task.\",\n \"Title: Adaptive context mediation in dynamic and large scale vehicular networks using relevance backpropagation\\nYear: 2008\\n\\nAbstract: Adaptive context mediation in large scale vehicle networks leads towards telematics which refers to the concept of vehicles equipped with context-aware embedded smart computing devices with communication capabilities over certain networks. With the use of telematics we can make use of wide range of smart inter-vehicle communication applications like emergency message transmission, collision avoidance, congestion monitoring and intelligent parking space locator. In this paper we present certain requirements for adaptive context-aware information mediation in large scale vehicle networks. We make use of quality attributes for context information and network properties of large scale vehicle networks and experiment with real time data collected using a car simulator. We simulate flooding and other dissemination based communication techniques with relevance backpropagation for large scale vehicle networks using OMNET++ to analyze the flow of context information. Our simulation results show that our context-aware and adaptive directed diffusion of information using relevance backpropagation increases the performance of the nodes in a large scale vehicle network with less communication overhead.\",\n \"Title: Walking in the Clouds: Deployment and Performance Trade-Offs of Smart Mobile Applications for Intelligent Environments.\\nYear: 2013\\n\\nAbstract: Cloud computing is still surfing the hype wave of emerging technologies. Delivering hardware, software and resources as a service over the network, the paradigm is also attracting a good deal of excitement in the mobile computing space. In this work, we challenge the proclaimed benefits of mobile cloud computing using smartphones as thin clients to access remote running applications, especially for applications that require contextual intelligence. Our experiments using mobile healthcare applications show that many resource and performance trade-offs exist and that current deployment schemes for these kind of applications are rough around the edges. We show how a modular design philosophy for mobile applications enables more optimal deployment and performance when leveraging cloud technology.\",\n \"Title: Efficient Synchronization For Stencil Computations Using Dynamic Task Graphs\\nYear: 2013\\n\\nAbstract: Executing stencil computations constitutes a significant portion of execution time for many numerical simulations running on high performance computing systems. Most parallel implementations of these stencil operations suffer from a substantial synchronization overhead. Furthermore, with the rapidly increasing number of cores these synchronization costs keep rising. This paper presents a novel approach for reducing the synchronization overhead of stencil computations by leveraging dynamic task graphs to avoid global barriers and minimizing spin-waiting, and exploiting basic properties of stencil operations to optimize the execution and memory management. Our experiments show a reduction in synchronization overhead by at least a factor four when compared to state-of-the-art stencil compilers like Pochoir and Patus.\",\n \"Title: Multi-dimensional Dependency and Conflict Resolution for Self-adaptable Context-aware Systems\\nYear: 2006\\n\\nAbstract: Self-adaptable systems dynamically adapt to satisfy new functionality requirements, to optimize performance and to adapt to variable runtime conditions. Context-aware systems acquire and utilize information about the context of a user and a device to provide personalized applications. Adaptation in a transparent way for the user is an important concern for both systems. To decrease the adaptation complexity of self-adaptable context-aware systems, we propose to model self-adaptation across three layers of abstractions: the runtime infrastructure, the context middleware and the user applications. The aim is to achieve per layer selfadaptation of the composition or behavior of these layers without jeopardizing the integrity and usability of the overall system. We discuss a multi-dimensional dependency and conflict resolution mechanism to guide self-adaptation and find a stable reconfiguration of the system at runtime.\",\n \"Title: Evaluation framework for adaptive context-aware routing in large scale mobile peer-to-peer systems\\nYear: 2011\\n\\nAbstract: The proliferation of novel wireless network technologies creates new opportunities for complex peer-to-peer information dissemination\\n systems. A key challenge that remains in this area is how to select the best algorithms and protocols to communicate effectively\\n on a large scale. In this paper, we focus in particular on large scale mobile networks where effectiveness depends on the\\n requirements of the application at hand and on the context of the peers in the network. We propose a framework for context-aware\\n adaptive information sharing that allows the evaluation of and comparison with alternative information routing protocols using\\n network metrics to measure a variety of quality attributes of the information dissemination protocols. These metrics can then\\n be used to verify which protocol is best suited for a particular application. We illustrate our evaluation framework with\\n different information dissemination protocols in an inter-vehicle communication scenario.\",\n \"Title: Encoding Semantic Awareness in Resource-Constrained Devices\\nYear: 2008\\n\\nAbstract: With the Semantic Web relying on ontologies to establish online machine-interpretable information, the Internet is growing into a semantically aware computing paradigm that facilitates Web entities' discovery of the knowledge and resources they need. Ambient intelligence aims to enable smart interaction beyond the Internet by embedding intelligence into our environment to unobtrusively support users' daily activities. To accomplish these goals, ontologies and semantic awareness are crucial for better understanding a user's context. While interest in the Semantic Web has spurred the development of large-scale semantic grid architectures, expanding the Semantic Web to the other end of the computing spectrum is a complex undertaking. The techniques and tools that support the Semantic Web aren't designed to deal with the resource-constrained devices with which people frequently interact in an ambient-intelligence environment. A proposed coding scheme for ontologies embeds semantic awareness in devices with limited memory and processing capabilities, such as sensory nodes and smart phones. This scheme provides a compact representation of an ontology and is enhanced with an efficient and effective semantic-matching algorithm similar to subsumption testing in many ontology reasoners.\",\n \"Title: A survey of software engineering best practices for the development of smart applications in Ambient Intelligence\\nYear: 2012\\n\\nAbstract: Over the past decade, the world of Ambient Intelligence and smart environments has brought us a wide variety of novel applications with potential for exhibiting sophisticated intelligent behavior. These applications are called smart because they can sense, anticipate and adapt themselves to the context, desires and intentions of their users. However, the unpredictability of human behavior, the unanticipated circumstances of execution and a growing heterogeneity of future operational environments impose significant development challenges if these innovative applications are to gain wide acceptance in our daily life. Therefore, applying well-established software engineering methodologies is a fundamental prerequisite for delivering high quality and robust smart software applications. This survey provides a illustrative presentation of software engineering best practices in the area of smart environments and Ambient Intelligence. The aim of this survey is not to explore and compare every possible related work in detail, but to offer insights into the latest developments in this domain and to further the research into the successful design, development and evaluation of Ambient Intelligence frameworks and applications. (This research is partially funded by the Interuniversity Attraction Poles Programme Belgian State, Belgian Science Policy, and by the Research Fund KU Leuven.)\",\n \"Title: Intelligent Widgets for Intuitive Interaction and Coordination in Smart Home Environments\\nYear: 2012\\n\\nAbstract: The intelligent home environment is a well-established example of the Ambient Intelligence application domain. A variety of sensors and actuators can be used to have the home environment adapt towards changing circumstances and user preferences. However, the complexity of how these intelligent home automation systems operate is often beyond the comprehension of non-technical users, and adding new technology to an existing infrastructure is often a burden. In this paper, we present a home automation framework designed based on smart widgets with a model driven methodology that raises the level of abstraction to configure home automation equipment. It aims to simplify user-level home automation management by mapping high-level home automation concepts onto a low-level composition and configuration of the automation building blocks with a reverse mapping to simplify the integration of new equipment into existing home automation systems. Experiments have shown that the mappings we proposed are sufficient to represent household appliances to the end user in a simple way and that new mappings can easily be added to our framework.\",\n \"Title: EASY: Efficient semAntic Service discoverY in pervasive computing environments with QoS and context support\\nYear: 2008\\n\\nAbstract: Pervasive computing environments are populated with networked software and hardware resources providing various functionalities that are abstracted, thanks to the Service Oriented Architecture paradigm, as services. Within these environments, service discovery enabled by service discovery protocols (SDPs) is a critical functionality for establishing ad hoc associations between service providers and service requesters. Furthermore, the dynamics, the openness and the user-centric vision aimed at by the pervasive computing paradigm call for solutions that enable rich, semantic, context- and QoS-aware service discovery. Although the semantic Web paradigm envisions to achieve such support, current solutions are hardly deployable in the pervasive environment due to the costly underlying semantic reasoning with ontologies. In this article, we present EASY to support efficient, semantic, context- and QoS-aware service discovery on top of existing SDPs. EASY provides EASY-L, a language for semantic specification of functional and non-functional service properties, as well as EASY-M, a corresponding set of conformance relations. Furthermore, EASY provides solutions to efficiently assess conformance between service capabilities. These solutions are based on an efficient encoding technique, as well as on an efficient organization of service repositories (caches), which enables both fast service advertising and discovery. Experimental results show that the deployment of EASY on top of an existing SDP, namely Ariadne, enhancing it only with slight changes to EASY-Ariadne, enables rich semantic, context- and QoS-aware service discovery, which furthermore performs better than the classical, rigid, syntactic matching, and improves the scalability of Ariadne.\",\n \"Title: Where people and cars meet: social interactions to improve information sharing in large scale vehicular networks\\nYear: 2010\\n\\nAbstract: Efficient delivery of information in vehicular networks is crucial for the creation of useful and usable applications that need to cope with nomadic large-scale environments. Context-awareness is often key to improve efficiency of a vehicle network since it allows to make informed decisions on the data routing, data locality and data necessity for different moving objects. In this paper we show how the social network of vehicle residents, as part of the overall context, allows us to improve the information sharing in the vehicular network significantly. We demonstrate this by deploying a social ubiquitous-help-system (UHS) on top of a vehicular network. We analyze how UHS operates in a vehicular network using a network simulation of realistic large scale vehicular movement data and show that the social interactions increases the efficiency, relevance and quality of information in data delivery.\",\n \"Title: A DSL for Context Quality Modeling in Context-Aware Applications.\\nYear: 2011\\n\\nAbstract: Developing reliable context-aware applications remains a big challenge, even after a decade of research in this area. Usually a lot of code is required to handle an application's correct behavior in a variety of different situations. Along with a growing amount of code, also increases the risk of programming errors that may lead to an undesired behavior in particular situations. In this paper we present a domain specific language (DSL) for developing context-aware applications. It allows creating context quality models which are transformed into software artifacts of the final application. This code generation saves time and effort, and helps to ensure an appropriate autonomic behavior at runtime in inherently uncertain situations.\",\n \"Title: A notion of event quality for contextualized planning and decision support systems\\nYear: 2011\\n\\nAbstract: This paper presents an approach for contextualizing an event-based decision support system for scheduling patient assessments in a hospital. To cope with unexpected delays, patient coordinators often pursue a worst case scenario when scheduling patient assessments, leading to an underutilization of human resources and equipment when the procedure went without complications. We present a context-based decision support system for patient planning that helps the patient coordinator with taking well-informed rescheduling decisions and anticipating changes in other patients' schedules. The system uses information and events produced by medical equipment. As these events can be nondeterministic, we demonstrate how our domain specific context model can be used to contextualize events to enhance their quality and ascertain their meaning.\",\n \"Title: A User-Oriented and Context-Aware Service Orchestration Framework for Dynamic Home Automation Systems\\nYear: 2010\\n\\nAbstract: The home environment has become increasingly sophisticated. Sensors and actuators allow a house to he programmed so that it can intelligently adapt to user needs. Unfortunately it has not become any easier for the user to manage all these devices. Our ontology driven framework describes a user-oriented automation system to help with this process by not only orchestrating home automation devices, but also by integrating new equipment and automating them as much as possible. By combining devices with a common functionality in a given context, relevant devices are pulled together in an intuitive user interface in which one can express preferences at a high level of abstraction. The big advantage is that our framework allows for the home environment to be adjusted without the user having to know about the technical details of devices in the home automation system.\",\n \"Title: Quality Extensions and Uncertainty Handling for Context Ontologies\\nYear: 2006\\n\\nAbstract: Context, by nature, involves real world entities and is therefore subject to uncertainty and inaccuracies. Ontologies are of- ten used to model context in a formal way in order to achieve a shared semantic understanding of concepts and the relationships that hold among them. However, they lack support for representing am- biguous context and appropriate comparison algorithms. As such, context-aware applications may make the assumption that the con- text they use is completely accurate. In this paper we propose a sim- ple and lightweight yet generic approach to extend context ontolo- gies with quality of context properties and discuss the use of these quality properties for context ontology matching under uncertainty using fuzzy set theory. We illustrate the proposed extensions and un- certainty mechanisms with a small example where uncertain spatio- temporal coverage is combined with other contextual properties.\",\n \"Title: Analyzing the efficiency of context-based grouping on collaboration in VANETs with large-scale simulation.\\nYear: 2014\\n\\nAbstract: Vehicle-to-vehicle and vehicle-to-infrastructure communication systems enable vehicles to share information captured by their local sensors with other interested vehicles. To ensure that this information is delivered at the right time and location, context-aware routing is vital for intelligent inter-vehicular communication. Traditional network addressing and routing schemes do not scale well for large vehicular networks. The conventional network multicasting and broadcasting cause significant overhead due to a large amount of irrelevant and redundant transmissions. To address these challenges, we first take into account contextual properties such as location, direction, and information interest to reduce the network traffic overhead. Second, to improve the relevancy of the received information we leverage the mobility patterns of vehicles and the road layouts to further optimize the peer-to-peer routing of the information. Third, to ensure our approach is scalable, we propose a context-based grouping mechanism in which relevant information is shared in an intelligent way within and between the groups. We evaluate our approach based on groups with common spatio-temporal characteristics. Our simulation experiments show that our context-based routing scheme and grouping mechanism significantly reduces the propagation of irrelevant and redundant information.\",\n \"Title: Learning distributed deployment and configuration trade-offs for context-aware applications in Intelligent Environments.\\nYear: 2014\\n\\nAbstract: The Internet of Things (IoT) is rapidly gaining ground as can be witnessed by the pervasive presence of the many things or objects around us that turn our surroundings into Intelligent Environments. These objects interact on a large scale in wired and wireless sensor and actuator networks using advanced communication protocols. Hence, IoT is an open ended and highly dynamic ecosystem with heterogeneous workloads and fluctuating resource availability. Distributed intelligence for smart objects and platforms is a vital enabling factor for IoT, but finding the best strategy to deploy and configure applications - especially those that require contextual intelligence - in a smart environment with dynamic and heterogeneous resource availability is far from straightforward. Our experiments using context-aware applications for Intelligent Environments show that many resource and performance trade-offs exist and that current deployment schemes for these kind of applications are rough around the edges. We illustrate how a modular design philosophy for smart IoT applications enables a more optimal deployments. Furthermore, we present a methodology to inspect and learn the trade-offs of different deployment schemes of IoT applications in order to autonomously optimize their configuration. We validated our methodology on different use cases and scenarios, and the results demonstrate the feasibility of our approach to automate the efficient deployment of IoT applications in the presence of multiple conflicting Quality of Service (QoS) objectives and varying runtime circumstances.\",\n \"Title: A Quality-aware Federated Framework for Smart Mobile Applications in the Cloud.\\nYear: 2014\\n\\nAbstract: Mobile Cloud Computing is an active research domain to investigate the ways of achieving a federation between mobile computing and cloud computing. Whereas, Ambient Intelligence aims to teach our mobile devices how to behave smart in our environment, narrowing the gap between people, their devices and the environment. These two domains behave as backbone for ubiquitous environment around us where everything is connected by sharing information and resources. Mobile devices use cloud resources to cope with ever-growing computing and storage demands for smart applications. Context provisioning in the cloud and mobile connectivity will give rise to new interactions with cloud infrastructure to effectively manage context information. However, as a lot of contextual information is being sensed and captured by mobile devices, it is not always clear whether it makes sense to upload all the raw sensed data to the cloud and have it processed there. Many resource and performance trade-offs exist for federated deployment of smart mobile applications. In this paper, we present a quality-aware federated framework to overcome the challenges for smart applications and to support the development and deployment of these applications, while opportunistically using cloud computing. The framework highlights the aspects of Quality-of-Context (QoC) provisioning and dynamic adaptability under uncertain context.\",\n \"Title: Enabling Self-learning in Dynamic and Open IoT Environments.\\nYear: 2014\\n\\nAbstract: The next big thing in computing is the Internet of Things (IoT), referring to dynamic and ever-evolving environments, generating high-volume streams of heterogeneous yet correlated contextual information of varying quality and complexity. Moreover, the increase in user mobility and unreliable sensor availability in IoT, necessitates the context-aware applications to dynamically adapt their behavior at run time. In this paper, we elicit the need for different self-learning techniques to tackle the openness of the IoT environments and propose enabling algorithms to achieve them. First, we present possible application scenarios which can benefit from both supervised and unsupervised self-learning. Later, we propose correlation mining algorithms based on Kullback-Leibler (KL) divergence and frequent set mining that exploits correlated contexts to enable unsupervised self-learning. These algorithms help to identify alternate sources for a context and semantically describe the previously unseen contexts in terms of already known contexts. We have realized the proposed algorithms on top of a Bayesian framework (HARD-BN) which supports autonomous learning. Our experiments demonstrate the applicability of the proposed correlation mining algorithms and their feasibility to enable self-learning in open and ever-evolving IoT environments.\",\n \"Title: Types in Their Prime: Sub-typing of Data in Resource Constrained Environments.\\nYear: 2013\\n\\nAbstract: Sub-typing of data improves reuse and allows for reasoning at different levels of abstraction; however, it is seldom applied in resource constrained environments. The key reason behind this is the increase in overhead that is caused by including hierarchical information in data types as compared to a flat list. Where hierarchical data typing is used, it is often represented using verbose textual identifiers or numerical encodings that are suboptimal with regards to space. In this paper, we present an encoding function for hierarchically typed information, based on the properties of prime numbers. It provides a compact representation of types, fast subsumption testing even on resource constrained platforms and support for the evolution of the data type hierarchy. We demonstrate the feasibility of our approach on two representative communication models in constrained environments; a publish/subscribe event bus and a RESTful application protocol. We evaluate the performance of our encoding function and show that it has limited overhead compared to a flat list of data types and that this overhead is outweighed by reduced memory and communication overhead once applied.\",\n \"Title: Design for Failure: Intelligent Systems Learning from Their Mistakes.\\nYear: 2014\\n\\nAbstract: Smart environments aim to make the life of their inhabitants more comfortable by having context-aware systems continuously work together to assist people with their daily tasks. However, all too often these assistive technologies are naively or optimistically developed assuming that systems can always anticipate what users want. Furthermore, the more these smart systems grow in complexity, the more prone to failure they become. The overall goal of this paper is to define new concepts and methodologies for the development of more reliable smart applications, and propose middleware support to analyze failures in context-aware behavior, culminating in a software-based safeguard that improves robustness against unforeseen human interventions, exceptional circumstances and unexpected events.\",\n \"Title: Scalar: A Distributed Scalability Analysis Framework\\nYear: 2014\\n\\nAbstract: Analyzing the scalability and quality of service of large scale distributed systems, such as cloud based services, requires a systematic benchmarking framework that is at least as scalable to sufficiently stress the system under test. This paper summarizes Scalar, our distributed, extensible load testing tool that can generate high request volumes using multiple coordinated nodes. It has support for communication and synchronization between user threads, and built-in node monitoring to detect resource bottlenecks in the benchmark framework deployment itself. Furthermore, it offers highly scalable results analysis that exploits data locality and characterizes the overall system scalability in terms of the Universal Scalability Law.\",\n \"Title: Scalability Analysis of the OpenAM Access Control System with the Universal Scalability Law\\nYear: 2014\\n\\nAbstract: The scalability of a software system is greatly impacted by the scalability of the underlying access control system, which makes analyzing the scalability of that access control system paramount. However, this is not trivial, as contemporary access control systems have a myriad of architectural deployment variations, each of which has a potentially large impact on overall system throughput. There is a need for a systematic approach to map these architectural variations to a reference model which allows to make comparisons and to identify trade-offs. This work provides a piece of the puzzle by demonstrating how this can be achieved by systematically applying the Universal Scalability Law (USL). We illustrate our approach by performing a rigorous scalability analysis of the OpenAM access control system for various deployment alternatives in the domain of authentication. We conclude that the approach is able to provide both qualitative and quantitative results which can be translated into practical operational recommendations for the envisioned types of system deployments.\",\n \"Title: Scalar: Systematic Scalability Analysis with the Universal Scalability Law\\nYear: 2014\\n\\nAbstract: Analyzing the scalability and quality of service of large scale distributed systems requires a highly scalable benchmarking framework with built-in communication and synchronisation functionality, which are features that are lacking in current load generation tools. This paper documents Scalar, our distributed, extensible scalability analysis tool that can generate high request volumes using multiple communicating, coordinated nodes. We show how Scalar offers analytics capabilities that support the Universal Scalability Law. We illustrate Scalar on an electronic payment case study, and find that the framework supports complex work flows and is able to characterize and give predictive insights into the quality of service and relative capacity of the system under test in function of the user load.\",\n \"Title: SAMURAI: A Streaming Multi-tenant Context-Management Architecture for Intelligent and Scalable Internet of Things Applications\\nYear: 2014\\n\\nAbstract: In the Internet of Things, heterogeneous and distributed streams of sensor events is a driver for context-aware behavior in intelligent environments. However, processing the event data usually cross-cuts the business logic of IoT applications and offering such reusable functionality as a service towards a variety of customers with different needs is often faced with scalability concerns. We present SAMURAI, a multi-tenant streaming context architecture that integrates and exposes well-known components for complex event processing, machine learning, knowledge representation, NoSQL persistence and in-memory data grids. SAMURAI pursues a twofold approach to achieve scalability: (1) distributed deployment with horizontal scalability, (2) shared resources through multi-tenancy. For the scenario used in the experimental evaluation of our architecture, the results show little overhead to support multi-tenancy, with near-linear scalability and flexible elasticity for deployment schemes with data partitioning per tenant.\",\n \"Title: When efficiency matters: Towards quality of context-aware peers for adaptive communication in VANETs\\nYear: 2011\\n\\nAbstract: In the near future vehicles will be equipped with embedded communication capabilities in order to perform context-sensitive tasks such as traffic flow control and incident avoidance. In large scale vehicular networks it is of vital importance that the information exchanged between the vehicles meets a certain level of quality so that they can make informed automated decisions. In this paper we define Quality of Context (QoC) and Peer Reputation (PR) for nodes in vehicular networks and propose ways to apply them for efficient communication. Thus, we provide a two-fold solution in which on the one hand we focus on the quality of the information and on the other hand we aim at determining the reputation of the nodes involved in the communication. This helps to eliminate the use of erroneous, ambiguous and imprecise information provided by unknown entities. Our simulated experiments show that our mechanism significantly reduces network traffic usage, eases out the decision making process and guarantees a minimum level of quality.\",\n \"Title: SAMURAI: A batch and streaming context architecture for large-scale intelligent applications and environments.\\nYear: 2016\\n\\nAbstract: Over the past decade intelligent environments have grown in sophistication. Many recent paradigm shifts - such as the Internet of Things (IoT), Ambient Assisted Living (AAL), e-health and telemedicine - envision large distributed networks of intelligent devices, applications and services that are sensitive to the presence of people and responsive to their needs. Cutting edge technologies will autonomously and collectively operate on a growing volume of information arriving at ever increasing velocities to transparently and non-intrusively support users during their activities. Especially the escalating variety of information that applications have to deal with is a non-trivial concern. Making sense out of heterogeneous and pervasive streams of sensor events to anticipate and address the needs of users is a ubiquitous challenge that many interactive context-aware applications in intelligent environments frequently face. Furthermore, software solutions that continuously interpret the tasks and contexts of a variety of individuals with different needs are often faced with scalability concerns. We present SAMURAI, a batch and streaming context architecture that integrates and exposes well-known components for complex event processing, machine learning, and knowledge representation. SAMURAI builds upon key concepts of the Lambda architecture and big data enabling technologies to achieve horizontal scalability and responsive interaction with its users. Two application cases validate the feasibility and performance of our context architecture, demonstrating near-linear scalability, flexible elasticity and smooth interaction capabilities.\",\n \"Title: Mobile device fingerprinting considered harmful for risk-based authentication\\nYear: 2015\\n\\nAbstract: In this paper, we present a critical assessment of the use of device fingerprinting for risk-based authentication in a state-of-practice identity and access management system. Risk-based authentication automatically elevates the level of authentication whenever a particular risk threshold is exceeded. Contemporary identity and access management systems frequently leverage browser-based device fingerprints to recognize trusted devices of a certain individual. We analyzed the variability and the predictability of mobile device fingerprints. Our research shows that particularly for mobile devices the fingerprints carry a lot of similarity, even across models and brands, making them less reliable for risk assessment and step-up authentication.\",\n \"Title: PRISM: Policy-driven Risk-based Implicit locking for improving the Security of Mobile end-user devices.\\nYear: 2015\\n\\nAbstract: Nowadays, most mobile applications rely on device screen locking mechanisms for ensuring practical security, which expects the users to explicitly authenticate with a PIN or biometric irrespective of the perceived threats. Owing to this usability issues, many avoid using device locks potentially compromising the security. To overcome the limitations of this binary approach, we present an implicit authentication framework called PRISM (Policy-driven Risk-based Implicit locking for improving the Security of Mobile end-user devices). It provides risk based authentication by detecting anomalies in the usual behavior patterns of the users which include their expected locations, activities and application usage. Its device unlocking decisions are driven by policies that are defined either automatically by mining sensor data or manually by the end-users. Our experiments show that PRISM is able to discover useful behavior patterns efficiently even with limited data. The number of required explicit authentications is significantly reduced while assuring the preferred security for everyday scenarios.\",\n \"Title: SmartAuth: dynamic context fingerprinting for continuous user authentication\\nYear: 2015\\n\\nAbstract: As recent incidents have shown, weak passwords are a severe security risk for authenticating users and granting access to protected resources. Additionally, strong passwords score low on usability, especially on mobile devices. In this work, we present SmartAuth, a scalable context-aware authentication framework built on top of OpenAM, a state-of-practice identity and access management suite. It uses adaptive and dynamic context fingerprinting based on Hoeffding trees to continuously ascertain whether a user's identity is authentic or not, and it respects privacy preferences by adopting consent-driven use of context information. We assess our approach from both an offensive and defensive security perspective. Our results show that dynamic context fingerprinting has good potential for a zero-interaction authentication scheme, with a minimal performance overhead compared to traditional authentication schemes.\",\n \"Title: To cloud or not to cloud: a context-aware deployment perspective of augmented reality mobile applications\\nYear: 2015\\n\\nAbstract: The resource limitations of mobile devices continue to impose constraints on the development of complex mobile applications. Performance and resource efficiency remains a challenge. We have examined resource utilization and performance trade-offs when extending an Augmented Reality (AR) application with context-awareness and cloud computing. The hypothesis is that the cost of these technologies is worth the benefits they result in. Our measurements show that filtered image datasets obtained through context-awareness result in lower latency and a reduced memory load when performing all AR computations on the mobile device. However, a cloud computing AR application does not benefit from in-depth context-awareness, as no part of the dataset is stored locally and the latency is approximately constant, relative to the Internet connectivity.\",\n \"Title: SparkXS: Efficient Access Control for Intelligent and Large-Scale Streaming Data Applications\\nYear: 2015\\n\\nAbstract: The exponential data growth in intelligent environments fuelled by the Internet of Things is not only a major push behind distributed programming frameworks for big data, it also magnifies security and privacy concerns about unauthorized access to data. The huge diversity and the streaming nature of data raises the demand for new enabling technologies for scalable access control that can deal with the growing velocity, volume and variety of volatile data. This paper presents SparkXS, an attribute-based access control solution with the ability to define access control policies on streaming latent data, i.e. hidden information made explicit through data analytics, such as aggregation, transformation and filtering. Experimental results show that SparkXS can enforce access control in a horizontally scalable way with minimal performance overheads.\",\n \"Title: Change Impact Analysis for Context-Aware Applications in Intelligent Environments.\\nYear: 2015\\n\\nAbstract: As software systems for context-aware applications and intelligent environments become increasingly complex and adaptive, the need to understand and predict the impact of changes grows. Such changes may manifest themselves (1) as alterations in the way users behave, (2) as software customizations to handle new requirements, and (3) as variations on the dynamic context in which intelligent environment systems are deployed and operate. Such internal and external changes may be anticipated or unforeseen in nature. With reliability being a key concern for intelligent environments, we revisit in this work the state-of-practice on change impact analysis (CIA) - a well-known methodology in software engineering - and investigate to what extent it can be applied and enhanced to contribute to the development of more reliable context-aware adaptive applications to increase the confidence in intelligent environment systems.\",\n \"Title: Accelerometer-Based Device Fingerprinting for Multi-factor Mobile Authentication.\\nYear: 2016\\n\\nAbstract: Due to the numerous data breaches, often resulting in the disclosure of a substantial amount of user passwords, the classic authentication scheme where just a password is required to log in, has become inadequate. As a result, many popular web services now employ risk-based authentication systems where various bits of information are requested in order to determine the authenticity of the authentication request. In this risk assessment process, values consisting of geo-location, IP address and browser-fingerprint information, are typically used to detect anomalies in comparison with the user's regular behavior. In this paper, we focus on risk-based authentication mechanisms in the setting of mobile devices, which are known to fall short of providing reliable device-related information that can be used in the risk analysis process. More specifically, we present a web-based and low-effort system that leverages accelerometer data generated by a mobile device for the purpose of device re-identification. Furthermore, we evaluate the performance of these techniques and assess the viability of embedding such a system as part of existing risk-based authentication processes.\",\n \"Title: Adaptive Dissemination For Mobile Electronic Health Record Applications With Proactive Situational Awareness\\nYear: 2016\\n\\nAbstract: Bring Your Own Device (BYOD) has been an emerging trend in the enterprise, including the healthcare domain. However, efficient and personalized content delivery for data intensive applications remains a technical challenge. In this work, we explore a mobile electronic health record (EHR) web application for general practitioners (GPs) on the mad for patient visits. Keeping all the health records up to date on a tablet is impossible due to resource constraints of the device, and dynamic planning of home visits. We therefore investigate how to deliver the right information at the right time under variable connectivity and limited resource availability. We present a flexible framework that capitalizes on situational awareness for proactive and adaptive content delivery to mobile applications. It leverages distributed probabilistic models and dynamic decision networks to improve the overall user experience with better on-device resource utilization. The added value is that it lifts the burden from the GP to customize and personalize the application by learning data consumption patterns in different contexts. Compared to baseline scenarios for this particular use case, our framework shows an improvement in the precision and recall with an acceptable runtime overhead for memory and CPU.\",\n \"Title: Feature-Based Variability Management For Scalable Enterprise Applications: Experiences With An E-Payment Case\\nYear: 2016\\n\\nAbstract: In today's world of electronic payments, which includes credit cards, gift cards, stored value accounts, and micro payments on mobile devices, successful payment services need to be sufficiently scalable and support diverging use cases to be successful. However, the interaction between horizontal scalability, feature variability and stringent performance and security concerns for these heterogeneous payment applications and stakeholders is not always cleat; which creates tension (and sometimes interference) in the successful development of these services. In this work, we identify crucial nonfunctional requirements for payment services and present a simple framework to map these requirements to existing approaches to achieve both horizontal and vertical scalability. We report on experiences with applying a service line engineering (SLE) approach towards payment services that combines cloud computing and SPL to support feature customization in a multi tenant payment service. We conclude with practical experiences and several lessons learned after applying this SPL engineering methodology on our industrial e-payment use case.\",\n \"Title: Mascot: Self-Adaptive Opportunistic Offloading For Cloud-Enabled Smart Mobile Applications With Probabilistic Graphical Models At Runtime\\nYear: 2016\\n\\nAbstract: Although extensive progress has been made in Mobile Cloud Augmentation, automated decision support on the device that enables the opportunistic and intelligent use of cloud resources is missing. Furthermore, we need solutions with reflective capabilities that can handle a changing environment and runtime variability. To simplify the deployment of smart mobile applications, we present a framework with retrospective decision support based on reinforcement learning to cater for various resource-performance trade-offs. We have adopted the MAPE-K (Monitor-Analyse-Plan-Execute-Knowledge) control loop architecture and realized the loop with Dynamic Decision Networks to manage self-adaptation at runtime. Our experiments show that our framework is capable of intelligently inferring appropriate decisions with an acceptable performance overhead of 10 milliseconds on mobile devices.\",\n \"Title: Security and privacy controls for streaming data in extended intelligent environments.\\nYear: 2016\\n\\nAbstract: Intelligent environments collect and process personal information to assist individuals with their daily activities, enhance their experiences and adapt to their needs and intentions. The prosperity of paradigms like the Internet of Things (IoT) will boost the development of intelligent environments, but the envisioned exponential data growth will give rise to serious security and privacy concerns. Already in the domains of smart homes and healthcare one can observe a growing trend of intelligent environments being extended with third party smart service and technology providers-such as cloud and Big Data analytics services-that analyze and visualize sensitive information as a means to offer new insights to their customers, but that typically cross the personal space or privacy boundaries of the intelligent environment. The challenge addressed in this work is how to offer Big Data processing capabilities as a service with appropriate data protection safeguards in order to protect the individual's privacy in the extended intelligent environment. In this paper, we present SparkXS, a framework which offers granular and scalable access and data protection control on streaming data that can deal with the growing velocity, volume and variety of volatile data of IoT, integrated on top of our SAMURAI lambda architecture for Big Data processing. Driven by upcoming legislation and obligations, such as the EU General Data Protection Regulation (GDPR), our framework applies Privacy by Design (PbD) strategies and offers security controls that empower users to better control their personal data. Experimental results with motivating use cases and large data sets demonstrate the feasibility and scalability of our SparkXS framework while operating with acceptable performance overheads.\",\n \"Title: Privacy-enabled remote health monitoring applications for resource constrained wearable devices.\\nYear: 2016\\n\\nAbstract: Recent computing paradigms like cloud computing and big data have become very appealing to outsource computation and storage, making it easier to realize personalized and patient centric healthcare through real-time analytics on user data. Although these technologies can significantly complement resource constrained mobile and wearable devices to store and process personal health information, privacy concerns are keeping patients from reaping the full benefits. In this paper, we present and evaluate a practical smart-watch based lifelog application for diabetics that leverages the cloud and homomorphic encryption for caregivers to analyze blood glucose, insulin values, and other parameters in a privacy friendly manner to ensure confidentiality such that even a curious cloud service provider remains oblivious of sensitive health data.\",\n \"Title: A model-driven approach for quality of context in pervasive systems.\\nYear: 2016\\n\\nAbstract: A proposal for modeling quality of context (QoC) for pervasive systems is presented.The MLContext modeling language is extended to support QoC.A Model-Driven approach is applied to generate software artefacts related to QoC.The proposal has been validated for the COSMOS and SAMURAI context-aware frameworks. Handling context is a crucial activity in context-aware systems. In building such systems, the creation of models helps developers to understand and reason on the context information. The quality of context information is required to achieve these systems behavior according to the requirements. Therefore, context models should not only represent the context information but also the quality of context (QoC). MLContext is a textual domain-specific language (DSL) designed to model context, which has been used to automatically generate software artifacts related to the context management for some context-aware frameworks. In this article we present an MLContext extension for modeling QoC. The QoC added features include constructs to express context situations (i.e. constraints on context information), quality requirements and quality levels. The new constructs have been mapped to code for two frameworks supporting QoC (COSMOS and SAMURAI). These mappings have been validated by means of a case study.\",\n \"Title: Data Protection Compliance Regulations and Implications for Smart Factories of the Future\\nYear: 2016\\n\\nAbstract: Context-aware systems in intelligent environments digest large amounts of data and personal information to gain situational awareness as a way to assist individuals with their daily activities, enhance their experiences and adapt to their needs and intention, whenever and wherever they are. Large amounts of data drive these environments, motivating the adoption of big data and cloud technologies. A similar digital transformation is taking place in the Factory of the Future and Industry 4.0, two paradigms on creating smart products through smart processes and procedures. As the attack surface for security and privacy threats grows, it is no surprise that new regulations and directives will be put in place to protect the privacy of individuals. In this paper, we discuss the foundational principles of Privacy by Design and key obligations of the upcoming EU General Data Protection Regulation (GDPR), and highlight how they impact the design and development of context-aware intelligent environments. We provide technical guidelines for better compliance with these regulatory frameworks.\",\n \"Title: Leveraging Battery Usage from Mobile Devices for Active Authentication.\\nYear: 2017\\n\\nAbstract: Active authentication is the practice of continuously verifying the identity of users, based on their context, interactions with a system, and information provided by that system. In this paper, we investigate if battery charge readings from mobile devices can be used as an extra factor to improve active authentication. We make use of a large data set of battery charge readings from real users and construct two computationally inexpensive machine learning classifiers to predict if a user session is authentic: the first one only based on the battery charge at a certain time of day; the second one predicts the authenticity of the user session when a previous, recent battery charge reading is available. Our research shows that a simple two-figure battery charge value can make a useful albeit minor contribution to active authentication.\",\n \"Title: The intelligent industry of the future: A survey on emerging trends, research challenges and opportunities in Industry 4.0.\\nYear: 2017\\n\\nAbstract: Strongly rooted in the Internet of Things and Cyber-Physical Systems-enabled manufacturing, disruptive paradigms like the Factory of the Future and Industry 4.0 envision knowledge-intensive industrial intelligent environments where smart personalized products are created through smart processes and procedures. The 4th industrial revolution will be based on Cyber-Physical Systems that will monitor, analyze and automate business processes, transforming production and logistic processes into smart factory environments where big data capabilities, cloud services and smart predictive decision support tools are used to increase productivity and efficiency. This survey provides insights into the latest developments in these domains, and identifies relevant research challenges and opportunities to shape the future of intelligent manufacturing environments.\",\n \"Title: Quality Parameters as Modeling Language Abstractions for Context-Aware Applications: An AAL Case Study.\\nYear: 2017\\n\\nAbstract: The quality of context information is still one of the most overlooked factors by developers and end-users, and this makes context-aware applications less reliable. While there is recent work in this area that focuses on identifying and modeling relevant quality parameters for context information, software developers still have not yet adopted these solutions at large because they do not offer the right set of abstractions that they are familiar with. This paper presents model and language constructs, as well as software engineering tools to address these quality of context concerns. We demonstrate our overarching solution on a non-trivial Ambient Assisted Living scenario involving assistance services for the elderly supported by indoor localization technologies.\",\n \"Title: Enhanced fraud detection as a service supporting merchant-specific runtime customization.\\nYear: 2017\\n\\nAbstract: We present a customizable, yet scalable data processing architecture for payment processors that aim to offer fraud detection as a service to e-commerce merchants. Due to the increasing complexity of payment solutions and the continuous evolution of fraud patterns, rule-based detection of fraudulent payments is no longer adequate. Our solution is implemented as a K-architecture for streaming big data, augmented with semantic web techniques to enable constrained customization for merchants. Our evaluation shows that our data processing architecture meets the stringent real-time processing limits of payment transactions, while offering runtime customization for multiple merchants.\",\n \"Title: Identity management for cyber-physical production workflows and individualized manufacturing in industry 4.0.\\nYear: 2017\\n\\nAbstract: Industry 4.0 envisions a digital transformation in the enterprise, entwining the cyber-physical world and real world of manufacturing to deliver networked production with enhanced process transparency. Production systems, smart products, data analytics and business processes in the cloud will interact directly with customers to realize the ambitious goal of single lot individualized manufacturing. An immediate consequence of the paradigm shift is an increased risk for cyber-security breaches. This paper presents and evaluates the performance and scalability of an identity management solution for dataflow-oriented processes to guarantee the authenticity and trustworthy access of users, machines, products and business processes in Industry 4.0 production workflows that operate across the organizational boundaries of the enterprise.\",\n \"Title: CEML: Mixing and moving complex event processing and machine learning to the edge of the network for IoT applications.\\nYear: 2016\\n\\nAbstract: The Internet of Things (IoT) is a growing field which is expected to generate and collect data everywhere at any time. Highly scalable cloud analytics systems are frequently being used to handle this data explosion. However, the ubiquitous nature of the IoT data imposes new technical and non-technical requirements which are difficult to address with a cloud deployment. To solve these problems, we need a new set of development technologies such as Distributed Data Mining and Ubiquitous Data Mining targeted and optimized towards IoT applications. In this paper, we present the Complex Event Machine Learning framework which proposes a set of tools for automatic distributed machine learning in (near-) real-time, automatic continuous evaluation tools, and automatic rules management for deployment of rules. These features are implemented for a deployment at the edge of the network instead of the cloud. We evaluate and validate our approach with a well-known classification problem.\",\n \"Title: A dynamic decision fusion middleware for trustworthy context-aware IoT applications.\\nYear: 2017\\n\\nAbstract: Internet of Things (IoT) devices offer new sources of contextual information, which can be leveraged by applications to make smart decisions. However, due to the decentralized and heterogeneous nature of such devices - each only having a partial view of their surroundings - there is an inherent risk of uncertain, unreliable and inconsistent observations. This is a serious concern for applications making security related decisions, such as context-aware authentication. We propose and evaluate a middleware for IoT that provides trustworthy context for a collaborative authentication use case. It abstracts a dynamic and distributed fusion scheme that extends the Chair-Varshney (CV) optimal decision fusion rule such that it can be used in a highly dynamic IoT environment. We compare performance and cost trade-offs against regular CV. Experimental evaluation demonstrates that our solution outperforms CV with 10% in a highly dynamic IoT environments, with the ability to detect and mitigate unreliable sensors.\",\n \"Title: Automated Feature Extraction for Website Fingerprinting through Deep Learning.\\nYear: 2017\\n\\nAbstract: Several studies have shown that the network traffic that is generated by a visit to a website over Tor reveals information specific to the website through the timing and sizes of network packets. By capturing traffic traces between users and their Tor entry guard, a network eavesdropper can leverage this meta-data to reveal which website Tor users are visiting. The success of such attacks heavily depends on the particular set of traffic features that are used to construct the fingerprint. Typically, these features are manually engineered and, as such, any change introduced to the Tor network can render these carefully constructed features ineffective. In this paper, we show that an adversary can automate the feature engineering process, and thus automatically deanonymize Tor traffic by applying our novel method based on deep learning. We evaluate our approach on a dataset comprised of more than three million network traces, which is the largest dataset of web traffic ever gathered for website fingerprinting, and find that the performance achieved by deep learning techniques is comparable to known approaches which include various research efforts spanning over multiple years. Furthermore, it eliminates the need for feature design and selection which is a tedious work and has been one of the main focus of prior work. We conclude that the ability to automatically construct the most relevant traffic features and perform accurate traffic recognition makes our deep learning based approach an efficient, flexible and robust technique for website fingerprinting.\",\n \"Title: Trustworthy Data-Driven Networked Production For Customer-Centric Plants\\nYear: 2017\\n\\nAbstract: Purpose - Industry 4.0 envisions a future of networked production where interconnected machines and business processes running in the cloud will communicate with one another to optimize production and enable more efficient and sustainable individualized/mass manufacturing. However, the openness and process transparency of networked production in hyperconnected manufacturing enterprises pose severe cyber-security threats and information security challenges that need to be dealt with. The paper aims to discuss these issues.Design/methodology/approach - This paper presents a distributed trust model and middleware for collaborative and decentralized access control to guarantee data transparency, integrity, authenticity and authorization of dataflow-oriented Industry 4.0 processes.Findings - The results of a performance study indicate that private blockchains are capable of securing IoT-enabled dataflow-oriented networked production processes across the trust boundaries of the Industry 4.0 manufacturing enterprise.Originality/value - This paper contributes a decentralized identity and relationship management for users, sensors, actuators, gateways and cloud services to support processes that cross the trust boundaries of the manufacturing enterprise, while offering protection against malicious adversaries gaining unauthorized access to systems, services and information.\",\n \"Title: Access Control with Delegated Authorization Policy Evaluation for Data-Driven Microservice Workflows.\\nYear: 2017\\n\\nAbstract: Microservices offer a compelling competitive advantage for building data flow systems as a choreography of self-contained data endpoints that each implement a specific data processing functionality. Such a 'single responsibility principle' design makes them well suited for constructing scalable and flexible data integration and real-time data flow applications. In this paper, we investigate microservice based data processing workflows from a security point of view, i.e., (1) how to constrain data processing workflows with respect to dynamic authorization policies granting or denying access to certain microservice results depending on the flow of the data; (2) how to let multiple microservices contribute to a collective data-driven authorization decision and (3) how to put adequate measures in place such that the data within each individual microservice is protected against illegitimate access from unauthorized users or other microservices. Due to this multifold objective, enforcing access control on the data endpoints to prevent information leakage or preserve one's privacy becomes far more challenging, as authorization policies can have dependencies and decision outcomes cross-cutting data in multiple microservices. To address this challenge, we present and evaluate a workflow-oriented authorization framework that enforces authorization policies in a decentralized manner and where the delegated policy evaluation leverages feature toggles that are managed at runtime by software circuit breakers to secure the distributed data processing workflows. The benefit of our solution is that, on the one hand, authorization policies restrict access to the data endpoints of the microservices, and on the other hand, microservices can safely rely on other data endpoints to collectively evaluate cross-cutting access control decisions without having to rely on a shared storage backend holding all the necessary information for the policy evaluation.\",\n \"Title: Privacy-Preserving Behavioral Authentication on Smartphones.\\nYear: 2017\\n\\nAbstract: User behavior analytics is playing a growing role in security decisions that grant or deny access to online services. Smartphone sensors can enhance PIN and pattern based mobile authentication by continuously monitoring user behavior. However, these schemes pose a privacy risk when sensitive data is disclosed to online service providers who desire to continuously assess the risk. In this paper we enhance behavioral authentication based on keystroke dynamics with privacy. To prevent service providers from reconstructing the original text typed by consumers, we implement and evaluate 3 privacy-preserving techniques: permutation, substitution and suppression. Applying the permutation technique leads to no measurable change in Equal Error Rate (EER). Thus, the EER while using permutation is the same as when no privacy preserving techniques are used, i.e. 16% for the 'user classification' and 18% for 'user clustering'. Adopting substitution, leads to an absolute increase in EER of 15% for the first task, and 11% for the second one, which gives a total of 31% and 39% respectively. For the suppression technique, the EER increases linearly with the number of keystrokes suppressed.\",\n \"Title: Frictionless Authentication Systems: Emerging Trends, Research Challenges and Opportunities.\\nYear: 2018\\n\\nAbstract: Authentication and authorization are critical security layers to protect a wide range of online systems, services and content. However, the increased prevalence of wearable and mobile devices, the expectations of a frictionless experience and the diverse user environments will challenge the way users are authenticated. Consumers demand secure and privacy-aware access from any device, whenever and wherever they are, without any obstacles. This paper reviews emerging trends and challenges with frictionless authentication systems and identifies opportunities for further research related to the enrollment of users, the usability of authentication schemes, as well as security and privacy trade-offs of mobile and wearable continuous authentication systems.\",\n \"Title: Policy reconciliation for access control in dynamic cross-enterprise collaborations.\\nYear: 2018\\n\\nAbstract: In dynamic cross-enterprise collaborations, different enterprises form a - possibly temporary - business relationship. To integrate their business processes, enterprises may need to grant each other limited access to their information systems. Authentication and authorization are key to secure information handling. However, access control policies often rely on non-standardized attributes to describe the roles and permissions of their employees which convolutes cross-organizational authorization when business relationships evolve quickly. Our framework addresses the managerial overhead of continuous updates to access control policies for enterprise information systems to accommodate disparate attribute usage. By inferring attribute relationships, our framework facilitates attribute and policy reconciliation, and automatically aligns dynamic entitlements during the evaluation of authorization decisions. We validate our framework with a Industry 4.0 motivating scenario on networked production where such dynamic cross-enterprise collaborations are quintessential. The evaluation reveals the capabilities and performance of our framework, and illustrates the feasibility of liberating the security administrator from manually provisioning and aligning attributes, and verifying the consistency of access control policies for cross-enterprise collaborations.\",\n \"Title: K8-Scalar: a workbench to compare autoscalers for container-orchestrated services (Artifact).\\nYear: 2018\\n\\nAbstract: This artifact is an easy-to-use and extensible workbench exemplar, named K8-Scalar, which allows researchers to implement and evaluate different self-adaptive approaches to autoscaling container-orchestrated services. The workbench is based on Docker, a popular technology for easing the deployment of containerized software that also has been positioned as an enabler for reproducible research. The workbench also relies on a container orchestration framework: Kubernetes (K8s), the de-facto industry standard for orchestration and monitoring of elastically scalable container-based services. Finally, it integrates and extends Scalar, a generic testbed for evaluating the scalability of large-scale systems with support for evaluating the performance of autoscalers for database clusters. \\r\\n\\r\\nThe associated scholarly paper presents (i) the architecture and implementation of K8-Scalar and how a particular autoscaler can be plugged in, (ii) sketches the design of a Riemann-based autoscaler for database clusters, (iii) illustrates how to design, setup and analyze a series of experiments to configure and evaluate the performance of this autoscaler for a particular database (i.e., Cassandra) and a particular workload type, (iv) and validates the effectiveness of K8-scalar as a workbench for accurately comparing the performance of different auto-scaling strategies. Future work includes extending K8-Scalar with an improved research data management repository.\",\n \"Title: Automated Website Fingerprinting through Deep Learning.\\nYear: 2018\\n\\nAbstract: Several studies have shown that the network traffic that is generated by a visit to a website over Tor reveals information specific to the website through the timing and sizes of network packets. By capturing traffic traces between users and their Tor entry guard, a network eavesdropper can leverage this meta-data to reveal which website Tor users are visiting. The success of such attacks heavily depends on the particular set of traffic features that are used to construct the fingerprint. Typically, these features are manually engineered and, as such, any change introduced to the Tor network can render these carefully constructed features ineffective. In this paper, we show that an adversary can automate the feature engineering process, and thus automatically deanonymize Tor traffic by applying our novel method based on deep learning. We collect a dataset comprised of more than three million network traces, which is the largest dataset of web traffic ever used for website fingerprinting, and find that the performance achieved by our deep learning approaches is comparable to known methods which include various research efforts spanning over multiple years. The obtained success rate exceeds 96% for a closed world of 100 websites and 94% for our biggest closed world of 900 classes. In our open world evaluation, the most performant deep learning model is 2% more accurate than the state-of-the-art attack. Furthermore, we show that the implicit features automatically learned by our approach are far more resilient to dynamic changes of web content over time. We conclude that the ability to automatically construct the most relevant traffic features and perform accurate traffic recognition makes our deep learning based approach an efficient, flexible and robust technique for website fingerprinting.\",\n \"Title: Semantic analysis and verification of context-driven adaptive applications in intelligent environments.\\nYear: 2016\\n\\nAbstract: With the advent of the Internet of Things (IoT) and Cyber-Physical Systems (CPS), assistive applications and smart environments can tap into a growing amount of context information to learn about their users, their surroundings and typical behavior. This information is useful to adapt intelligently, autonomously and non-intrusively to a myriad of circumstances. However, trustworthiness and reliable adaptation to changes in line with user expectations—especially to situations that the developers did not anticipate—remain key concerns. Understanding the impact of changes from a developer (design time) and system (runtime) perspective, and ensuring that no undesired side effects take place are two non-trivial research challenges to increase the adoption of such applications. Given the limited tool support for anticipating change at design time and runtime, we present our change impact analysis (CIA) methodology—found in the formal semantic modeling of intelligent environments and rule-based application behavior—to contribute to the development and deployment of reliable context-aware adaptive applications. We validate our contributions on non-trivial smart home and office scenarios, and demonstrate how our framework helps increase trust in intelligent environment applications by anticipating change implications upfront at design time and by minimizing the occurrence of undesired side effects at runtime.\",\n \"Title: Robust Digital Twin Compositions for Industry 4.0 Smart Manufacturing Systems\\nYear: 2018\\n\\nAbstract: Industry 4.0 is an emerging business paradigm that is reaping the benefits of enabling technologies driving intelligent systems and environments. By acquiring, processing and acting upon various kinds of relevant context information, smart automated manufacturing systems can make well-informed decisions to adapt and optimize their production processes at runtime. To manage this complexity, the manufacturing world is proposing the 'Digital Twin' model to represent physical products in the real space and their virtual counterparts in the virtual space, with data connections to tie the virtual and real products together for an augmented view of the manufacturing workflow. The benefits of such representations are simplified process simulations and efficiency optimizations, predictions, early warnings, etc. However, the robustness and fidelity of digital twins are a critical concern, especially when independently developed production systems and corresponding digital twins interfere with one another in a manufacturing workflow and jeopardize the proper behavior of production systems. We therefore evaluate the addition of safeguards to digital twins for smart cyber-physical production systems (CPPS) in an Industry 4.0 manufacturing workflow in the form of feature toggles that are managed at runtime by software circuit breakers. Our evaluation shows how these improvements can increase the robustness of interacting digital twins by avoiding local errors from cascading through the distributed production or manufacturing workflow.\",\n \"Title: Gait template protection using HMM-UBM\\nYear: 2018\\n\\nAbstract: This paper presents a hidden Markov model-Universal background model gait authentication system, which is also incorporated into a template protection based on a fuzzy commitment scheme. We show that with limited enrollment data the HMM-UBM system achieves a very competitive equal error rate of ≈1% using one sensor. The proposed template protection scheme benefits from eigen-features coming from multiple Universal background model systems fused with a novel technique that minimizes the bit error rate for genuine attempts. This allows the protected system to achieve a false rejection rate below 5% with an effective key length of 64 bits.\",\n \"Title: Internet of Things for enabling smart environments: A technology-centric perspective.\\nYear: 2019\\n\\nAbstract: The Internet of Things (IoT) is a computing paradigm whereby everyday life objects are augmented with computational and wireless communication capabilities, typically through the incorporation of resource-constrained devices including sensors and actuators, which enable their connection to the Internet. The IoT is seen as the key ingredient for the development of smart environments. Nevertheless, the current IoT ecosystem offers many alternative communication solutions with diverse performance characteristics. This situation presents a major challenge to identifying the most suitable IoT communication solution(s) for a particular smart environment. In this paper we consider the distinct requirements of key smart environments, namely the smart home, smart health, smart cities and smart factories, and relate them to current IoT communication solutions. Specifically, we describe the core characteristics of these smart environments and then proceed to provide a comprehensive survey of relevant IoT communication technologies and architectures. We conclude with our reflections on the crucial features of IoT solutions in this setting and a discussion of challenges that remain open for research.\",\n \"Title: Managing distributed trust relationships for multi-modal authentication.\\nYear: 2018\\n\\nAbstract: Multi-modal active authentication schemes fuse decisions of multiple behavioral biometrics (behaviometrics) to reduce identity verification errors. The challenge that we address in this work is the security risk caused by these decision fusion schemes making invalid assumptions, such as a fixed probability of (in)correct recognition and a temporal congruence of behaviometrics. To mitigate this risk, this paper presents a formal trust model that drives the behaviometric selection and composition. Our trust model adopts a hybrid approach combining policy and reputation based knowledge representation techniques. Our model and framework (1) externalizes trust knowledge from the authentication logic to achieve loosely coupled trust management, and (2) formalizes this knowledge in description logic to reason upon and broker complex distributed trust relationships to make risk-adaptive decisions for multi-modal authentication. The evaluation of our proof-of-concept illustrates an acceptable performance overhead while lifting the burden of manual trust and behaviometric management for multi-modal authentication.\",\n \"Title: Detection of algorithmically generated domain names used by botnets - a dual arms race.\\nYear: 2019\\n\\nAbstract: Malware typically uses Domain Generation Algorithms (DGAs) as a mechanism to contact their Command and Control server. In recent years, different approaches to automatically detect generated domain names have been proposed, based on machine learning. The first problem that we address is the difficulty to systematically compare these DGA detection algorithms due to the lack of an independent benchmark. The second problem that we investigate is the difficulty for an adversary to circumvent these classifiers when the machine learning models backing these DGA-detectors are known. In this paper we compare two different approaches on the same set of DGAs: classical machine learning using manually engineered features and a 'deep learning' recurrent neural network. We show that the deep learning approach performs consistently better on all of the tested DGAs, with an average classification accuracy of 98.7% versus 93.8% for the manually engineered features. We also show that one of the dangers of manual feature engineering is that DGAs can adapt their strategy, based on knowledge of the features used to detect them. To demonstrate this, we use the knowledge of the used feature set to design a new DGA which makes the random forest classifier powerless with a classification accuracy of 59.9%. The deep learning classifier is also (albeit less) affected, reducing its accuracy to 85.5%.\",\n \"Title: Special Issue: Big Data for context-aware applications and intelligent environments\\nYear: 2019\\n\\nAbstract: Disruptive paradigm shifts such as the Internet of Things (IoT) and Cyber–Physical Systems (CPS) are creating a wealth of streaming context information. Large-scale context-awareness combining IoT and Big Data drive the creation of smarter application ecosystems in diverse vertical domains, including smart health, finance, smart grids and cities, transportation, Industry 4.0, etc. This special issue addresses core topics on the design, the use and the evaluation of Big Data enabling technologies to build next-generation context-aware applications and computing systems for future intelligent environments.\",\n \"Title: A Systematic Comparison of Age and Gender Prediction on IMU Sensor-Based Gait Traces.\\nYear: 2019\\n\\nAbstract: Sensors provide the foundation of many smart applications and cyber-physical systems by measuring and processing information upon which applications can make intelligent decisions or inform their users. Inertial measurement unit (IMU) sensors-and accelerometers and gyroscopes in particular-are readily available on contemporary smartphones and wearable devices. They have been widely adopted in the area of activity recognition, with fall detection and step counting applications being prominent examples in this field. However, these sensors may also incidentally reveal sensitive information in a way that is not easily envisioned upfront by developers. Far worse, the leakage of sensitive information to third parties, such as recommender systems or targeted advertising applications, may cause privacy concerns for unsuspecting end-users. In this paper, we explore the elicitation of age and gender information from gait traces obtained from IMU sensors, and systematically compare different feature engineering and machine learning algorithms, including both traditional and deep learning methods. We describe in detail the prediction methods that our team used in the OU-ISIR Wearable Sensor-based Gait Challenge: Age and Gender (GAG 2019) at the 12th IAPR International Conference on Biometrics. In these two competitions, our team obtained the best solutions amongst all international participants, and this for both the age and gender predictions. Our research shows that it is feasible to predict age and gender with a reasonable accuracy on gait traces of just a few seconds. Furthermore, it illustrates the need to put in place adequate measures in order to mitigate unintended information leakage by abusing sensors as an unanticipated side channel for sensitive information or private traits.\",\n \"Title: AuthGuide: Analyzing Security, Privacy and Usability Trade-Offs in Multi-factor Authentication\\nYear: 2021\\n\\nAbstract: Multi-factor authentication (MFA) reduces the risk of compromised credentials. However, selecting, configuring and combining different authentication factors is a challenge for both security administrators and end-users, as the configuration possibilities are large and the implications of choices on security, privacy and usability are not always well understood. This concern is further aggravated when the security administrator grants the end-user some flexibility for the selection of authentication factors, or when the latter are combined in a risk-adaptive manner. In this work, we present AUTHGUIDE, an authentication knowledge and configuration framework that increases the awareness about these trade-offs. Additionally, it raises the level of abstraction to configure MFA for a given identity and access management (IAM) platform through a series of questions by mapping the responses onto the IAM's workflow of authentication steps for registration and login. We implemented AUTHGUIDE, validated it on top of the open source Keycloak IAM, and evaluated the effectiveness of our framework to analyze the security, privacy and usability trade-offs.\",\n \"Title: On the Security of Biometrics and Fuzzy Commitment Cryptosystems: A Study on Gait Authentication\\nYear: 2021\\n\\nAbstract: As biometric templates consist of highly correlated features, the real security level offered by biometric authentication systems remains an open research question. In this work we provide new approximations and a lower bound of the security offered by fuzzy commitment schemes. Fuzzy commitment cryptosystems and in general biometric template protection schemes play an important role in allowing for remote storage and processing of biometric data, as they mitigate the threat of biometric template leakage. The use of such schemes would alleviate some of the usability constraints imposed by the state-of-practice local use of biometrics. As such we conduct an in-depth security analysis for IMU based gait authentication systems, where we evaluate the effectiveness of attacks within the scope of two well-defined threat models that target both unprotected and protected systems. A pivotal enabler of our analysis is the development of nine different approaches to gait authentication, which allows us to perform intramodal fusion on these distinct, yet highly correlated biometric templates, and to protect them with a strengthened fuzzy commitment scheme. Our analysis clearly demonstrates the high correlation between the different biometric templates, which, among others, further showcases the threat of biometric template leakage. Furthermore, as our analysis incorporates a threat model that assumes biometric template leakage, it provides metrics for the security provided by the biometric modality itself.\",\n \"Title: Applying Machine Learning to use security oracles: a case study in virus and malware detection\\nYear: 2022\\n\\nAbstract: Machine Learning (ML) has a significant potential to enhance the security posture of an organization by improving threat detection and discovery. The growing quality and quantity of data through measurements creates opportunities in this context. However, when an organization does not have sufficient labeled data to make predictions, it can rely on third parties for expert advise. In this work, we present a real-world case study of a company offering security services to other businesses on top of its portfolio of internal security assets. The security provider adopts ML to learn when to cost-effectively invoke a third party service/oracle (i.e. VirusTotal), first to boost its own detection rate in order to protect its customers, and second to obtain new ground truth to further optimize its future oracle use, all under fixed query budget constraints. While the decision making of the ML system was very successful in terms of avoiding false positives and false negatives, we nonetheless identified several security challenges when adopting ML for a cost-effective use of security oracles. We evaluate our ML solution on real data, elicit various lessons learned about the increased attack surface when using ML in security applications, and identify countermeasures to secure this ML pipeline.\",\n \"Title: Captcha me if you can: Imitation Games with Reinforcement Learning\\nYear: 2022\\n\\nAbstract: Since their inception, Captchas have been widely used as reverse Turing tests for combating bot proliferation on the web. This has resulted in an arms race between bot developers that automate Captcha solvers and Captcha services that adjust the challenges accordingly or come up with new ones altogether. Ultimately, older generations could be bypassed consistently, and thus in the third version of reCAPTCHA, Google offers zero user friction. The intent in the new system is not only to avoid interrupting user experience but to also obfuscate the nature of the challenge itself, being much less prominent than a text or image recognition task. We introduce a methodology that learns through interaction how to evade detection, while collecting and analyzing reCAPTCHA v3 scores over fifteen months and various web environments. With reinforcement learning as the backbone, we build models that can simulate human-like web browsing behaviour by using the returned score as an informative signal. Our study exposes an important vulnerability: while the score is influenced by a multitude of undisclosed factors, it is easily accessible and it enables adversaries to learn and perfect evasive models. Notably, we demonstrate that our automation models, which integrate general web browsing capabilities, transfer between websites with an evasion rate up to 99.6%.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":89,"string":"89"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":247,"string":"247"}}},{"rowIdx":248,"cells":{"question_id":{"kind":"string","value":"Jian Yao"},"question":{"kind":"string","value":"Generate an abstract for the title \"Segmentation-based classification for 3D urban point clouds\" using the following items: Unified classification framework, 3D urban point clouds, segmentation approach, features extraction, contextual constraints."},"answer":{"kind":"string","value":"In this paper, we propose a unified classification framework for 3D urban point clouds. First of all, an efficient segmentation approach is utilized to segment 3D point clouds. For comparison, we employed two recently developed point clouds segmentation approaches. The first one is a region-growing-based segmentation algorithm by using robust saliency features and another one is a hierarchical-clustering-based algorithm. The former will produce large and complete segments while the latter will generate more small pieces of segments. Secondly, we extract a set of features from each segment for training and testing by using an effective classifier. For comparison, we employed two popularly used classifiers, Naïve Bayes (NB) classifier and support vector machine (SVM). Thirdly, the contextual constraints among objects is used to further refine the classification results based on segments via graph cuts optimization. Experimental results on 3D urban point clouds acquired by a vehicle LiDAR system illustrate that our proposed classification framework is effective."},"correct_answer":{"kind":"string","value":"In this paper, we propose a unified classification framework for 3D urban point clouds. First of all, an efficient segmentation approach is utilized to segment 3D point clouds. For comparison, we employed two recently developed point clouds segmentation approaches. The first one is a region-growing-based segmentation algorithm by using robust saliency features and another one is a hierarchical-clustering-based algorithm. The former will produce large and complete segments while the latter will generate more small pieces of segments. Secondly, we extract a set of features from each segment for training and testing by using an effective classifier. For comparison, we employed two popularly used classifiers, Naïve Bayes (NB) classifier and support vector machine (SVM). Thirdly, the contextual constraints among objects is used to further refine the classification results based on segments via graph cuts optimization. Experimental results on 3D urban point clouds acquired by a vehicle LiDAR system illustrate that our proposed classification framework is effective."},"documents":{"kind":"list like","value":["Title: Multi-Layer Background Subtraction Based On Color And Texture\nYear: 2007\n\nAbstract: In this paper, we propose a robust multi-layer background subtraction technique which takes advantages of local texture features represented by local binary patterns (LBP) and photometric invariant color measurements in RGB color space. LBP can work robustly with respective to light variation on rich texture regions but not so efficiently on uniform regions. In the latter case, color information should overcome LBPs limitation. Due to the illumination invariance of both the LBP feature and the selected color feature, the method is able to handle local illumination changes such as cast shadows from moving objects. Due to the use of a simple layer-based strategy, the approach can model moving background pixels with quasi-periodic flickering as well as background scenes which may vary over time due to the addition and removal of long-time stationary objects. Finally, the use of a cross-bilateral filter allows to implicitely smooth detection results over regions of similar intensity and preserve object boundaries. Numerical and qualitative experimental results on both simulated and real data demonstrate the robustness of the proposed method.","Title: Automatic laser-based identification for UF6 cylinders.\nYear: 2013\n\nAbstract: We present a laser item identification system (L2IS), installed in a real facility on trial, that is capable of automatically monitoring all transfers of uranium hexafluoride (UF) cylinders between different process areas. Each cylinder has a unique ‘fingerprint’ represented by the 3D micro-structure of its surface which remains intact even under extreme environmental conditions. L2IS automatically identifies each cylinder through exploring the 3D frontal surface acquired by the laser scanner. The system is composed of a portable unit (operated in attended mode) and a fixed installed unit (operated without inspector presence). The efficiency and accuracy of our identification system were evaluated on a large dataset acquired during several years including a full year of field testing.","Title: Global Uniform Synchronization With Estimated Error Under Transmission Channel Noise\nYear: 2009\n\nAbstract: This paper investigates the problem of estimating synchronization errors and its application to global uniform synchronization with an estimated error bound for the master-slave chaos synchronization scheme via linear control input, which is possibly subject to disturbances by unknown but bounded channel noise and time-delay. Based on Lyapunov function, Razumikhin technique, nonlinear parametric v...","Title: Fast Individual Facial Animation\nYear: 2005\n\nAbstract: We present a fast approach to generate individual face model and to produce relevant facial animation. Firstly, a frontal face image is captured with an ordinary video camera, and 85 key points are automatically detected. Then the points are used for RBF network to deform a generic model to an individual model. The texture is generated from the same image and texture coordinates are interpolated. Finally we transfer the original vertex motion vectors to the individual model in real time. All the procedure can be implemented with minimal or even without manual tuning. The result shows that our method is fast enough for common applications.","Title: Systematic Static Shadow Detection\nYear: 2004\n\nAbstract: A systematic static shadow detection algorithm for color images is presented in this paper. The image is modeled by an undirected graph and the shadow detection is achieved through maximizing the graph probability using the EM algorithm. Further analysis shows the connection between our model and the relaxation labeling (RL) model. Experiments clearly indicate that our method is superior to a state-of-the-art shadow detection algorithm.","Title: Efficient importance sampling for high-sigma yield analysis with adaptive online surrogate modeling\nYear: 2013\n\nAbstract: Massively repeated structures such as SRAM cells usually require extremely low failure rate. This brings on a challenging issue for Monte Carlo based statistical yield analysis, as huge amount of samples have to be drawn in order to observe one single failure. Fast Monte Carlo methods, e.g. importance sampling methods, are still quite expensive as the anticipated failure rate is very low. In this paper, a new method is proposed to tackle this issue. The key idea is to improve traditional importance sampling method with an efficient online surrogate model. The proposed method improves the performance for both stages in importance sampling, i.e. finding the distorted probability density function, and the distorted sampling. Experimental results show that the proposed method is 1e2X~1e5X faster than the standard Monte Carlo approach and achieves 5X~22X speedup over existing state-of-the-art techniques without sacrificing estimation accuracy.","Title: Automatic medical image annotation and retrieval\nYear: 2008\n\nAbstract: The demand for automatically annotating and retrieving medical images is growing faster than ever. In this paper, we present a novel medical image retrieval method for a special medical image retrieval problem where the images in the retrieval database can be annotated into one of the pre-defined labels. Even more, a user may query the database with an image that is close to but not exactly what he/she expects. The retrieval consists of the deducible retrieval and the traditional retrieval. The deducible retrieval is a special semantic retrieval and is to retrieve the label that a user expects while the traditional retrieval is to retrieve the images in the database which belong to this label and are most similar to the query image in appearance. The deducible retrieval is achieved using SEMI-supervised Semantic Error-Correcting output Codes (SEMI-SECC). The active learning method is also exploited to further reduce the number of the required ground truthed training images. Relevance feedbacks (RFs) are used in both retrieval steps: in the deducible retrieval, RF acts as a short-term memory feedback and helps identify the label that a user expects; in the traditional retrieval, RF acts as a long-term memory feedback and helps ground truth the unlabelled training images in the database. The experimental results on IMAGECLEF 2005 [] annotation data set clearly show the strength and the promise of the presented methods.","Title: Cournot Equilibrium in Price-Capped Two-Settlement Electricity Markets\nYear: 2005\n\nAbstract: We compare two alternative mechanisms for capping prices in two-settlement electricity markets. With sufficient lead time and competitive entry opportunities, forward market prices are implicitly capped by competitive pressure of potential entry that will occur when forward prices rise above a certain level. Another more direct approach is to cap spot prices through regulatory intervention. In this paper we explore the implications of the two alternative mechanisms in a two settlement Cournot equilibrium framework. We formulate the market equilibrium as a stochastic equilibrium problem with equilibrium constraints (EPEC) capturing congestion effects, probabilistic contingencies and market power. As an illustrative test case we use the 53-bus Belgian electricity network with representative generator cost but hypothetical demand and ownership assumptions. When compared to two-settlement systems without price caps we find that either of the price capping alternatives results in reduced forward contracting. Furthermore the reduction in spot prices due to forward contracting is smaller.","Title: Hybrid group search optimiser with quadratic interpolation method and its application\nYear: 2011\n\nAbstract: Group Search Optimiser (GSO) is a new swarm intelligence optimiser algorithm inspired by animal social behaviours. In this paper, we proposed two variants of GSO to improve its search capability, and applied them to solving non-linear equations. Producers in the GSO are like the eyes of animals, which determine the \"ï戮聵food' position and the movement direction of scroungers. However, due to the random sample mechanism, the computational efficiency is poor. To improve its search efficiency, a new GSO based on quadratic interpolation method (QIGSO) is proposed, in which the estimated position with quadratic interpolation theory is used to replace the random point in each iteration to increase the speed of convergence. Furthermore, the steepest gradient descent method is also incorporated into QIGSO (QIGSO_SDO) to improve the local search capability. Numerical simulation and a special problem about radar detection are used to test the proposed two variants.","Title: An efficient image-based rendering method\nYear: 2004\n\nAbstract: Given a set of images of the same scene, we propose an efficient method for realistically synthesizing a new image seen from a new viewpoint. Compared with some existing techniques which explicitly reconstruct the 3D geometry of the scene, we directly reconstruct the colour of each pixel in the new image by utilizing a weighted photoconsistency constraint. Global photoconsistency constraint of one pixel is firstly utilized to generate a list of plausible colours for each rendered pixel in the new image. Considering the existing of partial occlusion or the deficiencies in the image-formation model, we iteratively update the colour for each rendered pixel based on local texture statistics similar to the input images. Experimental results on the generation of a new image from a new viewing position from a set of input images show that our proposed method is promising and satisfactory.","Title: Cournot Equilibria In Two-Settlement Electricity Markets With System Contingencies\nYear: 2007\n\nAbstract: We study Nash equilibrium in two-settlement competitive electricity markets with horizontal market power, flow congestion, demand uncertainties and probabilistic system contingencies. The equilibrium is formulated as a stochastic Equilibrium Problem with Equilibrium Constraints (EPEC) in which each firm solves a stochastic Mathematical Programme with Equilibrium Constraints (MPEC). We assume a no-arbitrage relationship between the forward prices and the spot prices. We find that, with two settlements, the generation firms have incentives to commit forward contracts, which increase social surplus and decrease spot energy prices. Furthermore, these effects are amplified when the markets become less concentrated.","Title: Image-based modeling and rendering from multiple views: a multiple cues based propagation approach\nYear: 2005\n\nAbstract: In this paper we present a method for modeling a complex scene from a small set of images and then synthesizing a new view. Consider one of input images as the reference image, a small set of reliable pixel matches are initially selected and then propagated to neighboring pixels based on the clustering-based light invariant photoconsistency constraint and the data-driven depth smoothness constraint, which are integrated into a pixel matching quality function to deal with occlusions, light changes and depth discontinuity. The mismatched points in propagation are then iteratively rectified. Thus, the 3D structures of the scene are expressed by a large set of densely matched 3D points. For a new view, we initialize it by projecting these matched points. Both match propagation and mismatch rectification are used to complete the whole rendering task.","Title: A video based personalized face model generation approach for network 3d games\nYear: 2005\n\nAbstract: We have developed a fast generation system for personalized 3D face model and plan to apply it in network 3D games. This system uses one video camera to capture player’s frontal face image for 3D modeling and dose not need calibration and plentiful manual tuning. The 3D face model in games is represented by a 3D geometry mesh and a 2D texture image. The personalized geometry mesh is obtained by deforming an original mesh with the relative positions of the player’s facial features, which are automatically detected from the frontal image. The relevant texture image is also obtained from the same image. In order to save storage space and network bandwidth, only the feature data and texture data from each player are sent to the game server and then to other clients. Finally, players can see their own faces in multiplayer games.","Title: Sparse Key Points Controlled Animation for Individual Face Model\nYear: 2008\n\nAbstract: We use RBF deformation and normal projection to regulate the scanned facial model, which makes their topology equivalent to a regular grid mesh and can generate principle components. Then the synthesized individual face model can be directly flatten to a regular plan, so the motion vectors of vertexes can be interpolated with barycentric coordinate. The regulation and animation remapping needs less than 40 key points and can work in real-time","Title: Importance Boundary Sampling for SRAM Yield Analysis With Multiple Failure Regions\nYear: 2014\n\nAbstract: SRAM cells generally require an extremely low failure rate (i.e., high yield) in the per cell basis to ensure a reasonably moderate yield for the whole chip. Existing yield analysis methods still encounter issues related to multiple failure regions resulting from high-dimensional process parameter space and/or multiple performance specifications. This paper proposes a new method that combines the advantages of existing importance sampling and boundary searching methods, and avoids issues in both. The key idea is to first find all likely failure regions and then, do importance sampling on these regions. Surrogate models are used to further accelerate the method so that SPICE-simulations can be highly reduced. Experimental results show that the proposed method is suitable for handling problems with multiple failure regions. Meanwhile, it can provide $5{\\rm X}{\\sim}20{\\rm X}$ speed-up over other existing techniques.","Title: A multimodal approach to time-invariant scene retrieval from single overhead image\nYear: 2004\n\nAbstract: We investigate a practical problem of time-invariant scene retrieval from single airport overhead image. A multimodal approach is developed to solving for the problem, in which an efficient method using image modality data is developed for time-specific object detection, and a method using graphics modality data is developed for removal of the detected objects. Theoretical analyses and experimental evaluations show the efficiency and the effectiveness of the approach.","Title: A unified fuzzy feature indexing scheme for region based online image querying\nYear: 2003\n\nAbstract: We describe a novel indexing and retrieval methodology integrating color, texture and shape information for content-based image retrieval in online image databases. This methodology, called PicSearcher, applies unsupervised image segmentation to partition an image into a set of regions, then fuzzy color histogram as well as fuzzy texture and shape properties of each region is calculated to be part of their signatures. The fuzzification procedures resolve the recognition uncertainty stemming from color quantization and human perception of colors. At the same time, this unified fuzzy scheme incorporates the segmentation-related uncertainties into the retrieval algorithm. Then an adaptive and effective measure for the overall similarity between images is developed by integrating properties of all the regions in the image. An implemented prototype system of PicSearcher has demonstrated a promising retrieval performance for an online test database containing 10,000 general-purpose color images, as compared with its peer systems in the literature.","Title: Object Detection in Aerial Imagery Based on Enhanced Semi-Supervised Learning\nYear: 2005\n\nAbstract: Object detection in aerial imagery has been well studied in computer vision for years. However, given the complexity of large variations of the appearance of the object and the background in a typical aerial image, a robust and efficient detection is still considered as an open and challenging problem. In this paper, we present the Enhanced Semi-Supervised Learning (ESL) framework and apply this framework to revising an object detection methodology we have developed in a previous effort. Theoretic analysis and experimental evaluation using the UCI machine learning repository clearly indicate the superiority of the ESL framework. The performance evaluations of the revised object detection methodology against the original one clearly demonstrate the promise and superiority of this approach.","Title: \"Automatic\" multimodal medical image fusion\nYear: 2003\n\nAbstract: This paper addresses the multimodal medical image fusion problem. To deliver the expected fusion accuracy, most of the state-of-the-art fusion algorithms have the typical requirement - a set of fiducial points between the two modalities of the images to \"guide\" the fusion. This paper aims at removing this requirement, resulting in an \"automatic\" multimodal medical image fusion methodology based on an innovative model using Electro Static Equilibrium theory called ESE that can be used in clinical diagnoses and evaluations with accepted fusion accuracy. By \"automatic\", it is meant that the fusion algorithm per se does not require fiducial points; it does require a certain form of human interactions in terms of providing users a list of parameter settings at the beginning of the fusion, that are case-based, anatomy-based, and image-modality-based, and it does even allow users to have an option to change the specific values of the parameter settings to accommodate specific clinical needs. This \"automatic\" approach allows radiologists to save their time/effort in identifying and marking the fiducial points in the images, allows physicians and radiologists to apply their domain expertise more intelligently in \"playing with\" different parameter settings in a higher level when running this algorithm in diagnoses, and also allows patients to avoid the inconvenience to be placed under the fiducial markings. Preliminary evaluations against one of the existing fusion methods have shown that ESE holds a great promise in future medical applications.","Title: 3D modeling and rendering from multiple wide-baseline images by match propagation\nYear: 2006\n\nAbstract: In this paper, we present a method for modeling a complex scene from a small set of input images taken from widely separated viewpoints and then synthesizing novel views. First, we find sparse correspondences across multiple input images and calibrate these input images taken with unknown cameras. Then one of the input images is chosen as the reference image for modeling by match propagation. A sparse set of reliably matched pixels in the reference image is initially selected and then propagated to neighboring pixels based on both the clustering-based light invariant photoconsistency constraint and the data-driven depth smoothness constraint, which are integrated into a pixel matching quality function to efficiently deal with occlusions, light changes and depth discontinuity. Finally, a novel view rendering algorithm is developed to fast synthesize a novel view by match propagation again. Experimental results show that the proposed method can produce good scene models from a small set of widely separated images and synthesize novel views in good quality.","Title: Analyzing Semantic Segmentation Using Hybrid Human-Machine CRFs\nYear: 2013\n\nAbstract: Recent trends in semantic image segmentation have pushed for holistic scene understanding models that jointly reason about various tasks such as object detection, scene recognition, shape analysis, contextual reasoning. In this work, we are interested in understanding the roles of these different tasks in aiding semantic segmentation. Towards this goal, we \"plug-in\" human subjects for each of the various components in a state-of-the-art conditional random field model (CRF) on the MSRC dataset. Comparisons among various hybrid human-machine CRFs give us indications of how much \"head room\" there is to improve segmentation by focusing research efforts on each of the tasks. One of the interesting findings from our slew of studies was that human classification of isolated super-pixels, while being worse than current machine classifiers, provides a significant boost in performance when plugged into the CRF! Fascinated by this finding, we conducted in depth analysis of the human generated potentials. This inspired a new machine potential which significantly improves state-of-the-art performance on the MRSC dataset.","Title: A fast individual face modeling and facial animation system\nYear: 2006\n\nAbstract: In this paper, we present a fast individual face modeling and animation system. The input of the system is a single frontal face image, which is captured by an ordinary video camera. And the output is 3D individual facial animation. Firstly, an Adaboost method is used to detect the face in the image. Then the key points of the face are located with the inverse compositional algorithm based active appearance models (AAM). The 3D geometry mesh of the individual face is then generated with morphable models. Finally, the direction and magnitude of existed motion vectors are adjusted according to different 3D face shapes using expression cloning technique. With this system, we can achieve realistic 3D facial animation with minimal and often no manual tuning. The experiments show that our system is fast enough for common applications.","Title: Fast human detection from joint appearance and foreground feature subset covariances\nYear: 2011\n\nAbstract: We present a fast method to detect humans from stationary surveillance videos. It is based on a cascade of LogitBoost classifiers which use covariance matrices as object descriptors. We have made several contributions. First, our method learns the correlation between appearance and foreground features and show that the human shape information contained in foreground observations can dramatically improve performance when used jointly with appearance cues. This contrasts with traditional approaches that exploit background subtraction as an attentive filter, by applying still image detectors only on foreground regions. As a second contribution, we show that using the covariance matrices of feature subsets rather than of the full set in boosting provides similar or better performance while significantly reducing the computation load. The last contribution is a simple image rectification scheme that removes the slant of people in images when dealing with wide angle cameras, allowing for the appropriate use of integral images. Extensive experiments on a large video set show that our approach performs much better than the attentive filter paradigm while processing 5–20 frames/s. The efficiency of our subset approach with state-of-the-art results is also demonstrated on the INRIA human (static image) database.","Title: Robust multi-view feature matching from multiple unordered views\nYear: 2007\n\nAbstract: This paper explores the problem of multi-view feature matching from an unordered set of widely separated views. A set of local invariant features is extracted independently from each view. First we propose a new view-ordering algorithm that organizes all the unordered views into clusters of related (i.e. the same scene) views by efficiently computing the view-similarity values of all view pairs by reasonably selecting part of extracted features to match. Second a robust two-view matching algorithm is developed to find initial matches, then detect the outliers and finally incrementally find more reliable feature matches under the epipolar constraint between two views from dense to sparse based on an assumption that changes of both motion and feature characteristics of one match are consistent with those of neighbors. Third we establish the reliable multi-view matches across related views by reconstructing missing matches in a neighboring triple of views and efficiently determining the states of matches between view pairs. Finally, the reliable multi-view matches thus obtained are used to automatically track all the views by using a self-calibration method. The proposed methods were tested on several sets of real images. Experimental results show that it is efficient and can track a large set of multi-view feature matches across multiple widely separated views.","Title: Two-settlement electricity markets with price caps and Cournot generation firms\nYear: 2007\n\nAbstract: We compare two alternative mechanisms for capping prices in two-settlement electricity markets. With sufficient lead time, forward market prices are implicitly capped by competitive pressure of potential entry that will occur when forward prices rise above some backstop price. Another more direct approach is to cap spot prices through a regulatory intervention. In this paper we explore the implications of these two alternative mechanisms in a two-settlement Cournot equilibrium framework. We formulate the market equilibrium as a stochastic equilibrium problem with equilibrium constraints (EPEC) capturing congestion effects, probabilistic contingencies and horizontal market power. As an illustrative test case, we use the 53-bus Belgian electricity network with representative generator costs but hypothetical demand and ownership structure. Compared to a price-uncapped two-settlement system, a forward cap increases firms’ incentives for forward contracting, whereas a spot cap reduces such incentives. Moreover, in both cases, more forward contracts are committed as the generation resource ownership structure becomes more diversified.","Title: Efficient model-based linear head motion recovery from movies\nYear: 2004\n\nAbstract: In this paper, we propose an efficient method that estimates the motion parameters of a human head from a video sequence by using a three-layer linear iterative process. In the innermost layer, we estimate the motion of each input face image in a video sequence based on a generic face model and a small set of feature points. A fast iterative least-square method is used to recover these motion parameters. After that, we iteratively estimate three model scaling factors using multiple frames with the recovered poses in the middle layer. Finally, we update 3D coordinates of the feature points on the generic face model in the outermost layer. Since all iterative processes can be solved linearly, the computational cost is low. Tests on synthetic data under noisy conditions and two real video sequences have been performed. Experimental results show that the proposed method is robust and has good performance.","Title: Robust range image registration using 3D lines\nYear: 2010\n\nAbstract: We present an efficient method for accurate automatic registration of two geometrically complex 3D range scans by using 3D lines. We first detect edges from the associated 2D reflectance images and collect 3D edge contours by only taking into account valid foreground points. Then we use an efficient split-and-merge line fitting algorithm to detect 3D lines. We build a fast search codebook to efficiently match the two sets of 3D lines. This is done by computing the orientation angle and distance of pairs of 3D lines in each set, both of which are invariant under rigid transformations. Finally we recover the rigid transformation between two scans using an efficient RANSAC algorithm with robust transformation estimation that exploits two sets of corresponding 3D lines. We conclude presenting experimental results that demonstrate efficiency and accuracy of our proposed method.","Title: Semi-supervised learning based object detection in aerial imagery\nYear: 2005\n\nAbstract: Object detection in aerial imagery has been well studied in computer vision for years. However, given the complexity of large variations of the appearance of the object and the background in a typical aerial image, a robust and efficient detection is still considered as an open and challenging problem. In this paper, we have developed a theoretic foundation for aerial imagery object detection using semi-supervised learning algorithms. Based on this theory, we have proposed a context-based object detection methodology. Both theoretic analyses and experimental evaluations have successfully demonstrated the great promise of the developed theory and the related detection methodology.","Title: 3D modeling from multiple images\nYear: 2010\n\nAbstract: Although the visual perception of 3D shape from 2D images is a basic capability of human beings, it remains challenging to computers Hence, one goal of vision research is to computationally understand and model the latent 3D scene from the captured images, and provide human-like visual system for machines In this paper, we present a method that is capable of building a realistic 3D model for the latent scene from multiple images taken at different viewpoints Specifically, the reconstruction proceeds in two steps First, generate dense depth map for each input image by a Bayesian-based inference model Second, build a complete 3D model for the latent scene by integrating all reliable 3D information embedded in the depth maps Experiments are conducted to demonstrate the effectiveness of the proposed approach.","Title: Complex and photo-realistic scene representation based on range planar segmentation and model fusion\nYear: 2011\n\nAbstract: We present an efficient 3D scene representation method from a set of 3D range scans captured from a large-scale indoor or outdoor scene based on range planar segmentation and model fusion. In our method, range images are partitioned into planar patches and non-planar regions. We first partition the range image into a set of rectangle blocks and fit a planar patch to all points of each block. Blocks that are not successfully fitted as planar patches, are iteratively partitioned into sub-blocks until reaching a minimum size. Second, we iteratively merge the planar patches and identify unclassified rectangle blocks or points. The segmentation is then refined by relabelling the boundary points of fitted planar patches with respect to the neighbouring planar patches. We further simplify the scene model representation by fusing range scans and welding neighbouring planar patches with clean straight boundaries. An efficient texture mapping approach is proposed to automatically map the reflectance/colour images onto the fused scene model composed of a set of planar patches. Finally we successfully demonstrate the performance of our algorithms on several challenging range data sets.","Title: Automatic Medical Image Annotation and Retrieval Using SECC\nYear: 2006\n\nAbstract: The demand for automatically annotating and retrieving medical images is growing faster than ever. In this paper, we present a novel medical image annotation method based on the proposed Semantic Error-Correcting output Codes (SECC). With this annotation method, we present a new semantic image retrieval method, which exploits the high level semantic similarity. For example, a user may query the system using an image of arm while he/she expects images of hand. This cannot be realized by traditional retrieval methods. The experimental results on the IMAGECLEF 2005 annotation data set clearly show the strength and the promise of the presented methods.","Title: Hierarchical shadow detection for color aerial images\nYear: 2006\n\nAbstract: A hierarchical shadow detection algorithm for color aerial images is presented in this paper to meet two challenges for static shadow detection in the literature: different brightness and illumination conditions in different images and the complexity of aerial images. The hierarchical algorithm consists of two levels of processing: the pixel level classification, achieved through modelling an image as a reliable graph (RG) and maximizing the graph reliability using the EM algorithm, and the region level verification, achieved through minimizing the Bayesian error by further exploiting the domain knowledge. Further analyses show that MRF model based segmentation is a special case of the RG model. The relationship between the RG model and the relaxation labeling model is also discussed. A quantitative comparison between this method and a state-of-the-art shadow detection algorithm clearly indicates that this method is promising for delivering effective shadow detection performance under different illumination and brightness conditions.","Title: Robust surface registration using N-points approximate congruentsets\nYear: 2011\n\nAbstract: Scans acquired by 3D sensors are typically represented in a local coordinate system. When multiple scans, taken from different locations, represent the same scene these must be registered to a common reference frame. We propose a fast and robust registration approach to automatically align two scans by finding two sets of N-points, that are approximately congruent under rigid transformation and leading to a good estimate of the transformation between their corresponding point clouds. Given two scans, our algorithm randomly searches for the best sets of congruent groups of points using a RANSAC-based approach. To successfully and reliably align two scans when there is only a small overlap, we improve the basic RANSAC random selection step by employing a weight function that approximates the probability of each pair of points in one scan to match one pair in the other. The search time to find pairs of congruent sets of N-points is greatly reduced by employing a fast search codebook based on both binary and multi-dimensional lookup tables. Moreover, we introduce a novel indicator of the overlapping region quality which is used to verify the estimated rigid transformation and to improve the alignment robustness. Our framework is general enough to incorporate and efficiently combine different point descriptors derived from geometric and texture-based feature points or scene geometrical characteristics. We also present a method to improve the matching effectiveness of texture feature descriptors by extracting them from an atlas of rectified images recovered from the scan reflectance image. Our algorithm is robust with respect to different sampling densities and also resilient to noise and outliers. We demonstrate its robustness and efficiency on several challenging scan datasets with varying degree of noise, outliers, extent of overlap, acquired from indoor and outdoor scenarios.","Title: Automatic Medical Image Annotation And Retrieval Using Semi-Secc\nYear: 2006\n\nAbstract: The demand for automatically annotating and retrieving medical images is growing faster than ever. In this paper, we present a novel medical image retrieval method based on SEMI-supervised Semantic Error-Correcting output Codes (SEMI-SECC). The experimental results on IMAGECLEF 2005 [1] annotation data set clearly show the strength and the promise of the presented methods.","Title: Clustering-based match propagation for image-based rendering from multiple images\nYear: 2004\n\nAbstract: In this paper we propose a novel method for rendering a new view from multiple input images. A set of reliable pixel matches are initially selected and then propagated to neighboring pixels based on the piecewise smooth assumption in the spatial domain and the clustering-based photoconsistency constraint which is applied to handle pixel occlusion, partial pixel effects and lighting effects between images. Experimental results show that the proposed algorithm is promising and satisfactory.","Title: Automatic marker detection from X-ray images\nYear: 2013\n\nAbstract: In this paper, we present a novel automatic marker detection method for X-ray images in the framework of machine learning, which is different from those approaches using traditional template matching or fitting algorithms based on prior knowledge. First we propose to use the covariance-based descriptors to effectively represent the marker features in X-ray images. Then we utilize the cascade of LogitBoost classifiers based on covariance features to learn the marker detector, which automatically locates the markers on a X-ray image with a high detection rate and a low false alarm rate. Finally a large amount of experimental results demonstrate that our proposed approach is quite suitable and effective for the marker detection in X-ray images.","Title: Modeling and Computing Two-Settlement Oligopolistic Equilibrium in a Congested Electricity Network\nYear: 2008\n\nAbstract: A model of two-settlement electricity markets is introduced, which accounts for flow congestion, demand uncertainty, system contingencies, and market power. We formulate the subgame perfect Nash equilibrium for this model as an equilibrium problem with equilibrium constraints (EPEC), in which each firm solves a mathematical program with equilibrium constraints (MPEC). The model assumes linear demand functions, quadratic generation cost functions, and a lossless DC network, resulting in equilibrium constraints as a parametric linear complementarity problem (LCP). We introduce an iterative procedure for solving this EPEC through repeated application of an MPEC algorithm. This MPEC algorithm is based on solving quadratic programming subproblems and on parametric LCP pivoting. Numerical examples demonstrate the effectiveness of the MPEC and EPEC algorithms and the tractability of the model for realistic-size power systems.","Title: Fusing color and texture features for stereo matching\nYear: 2013\n\nAbstract: This paper presents a novel method for stereo matching by fusing color and texture features. Instead of using color features only, which is very similar to most of stereo matching algorithms proposed in recent years, we propose to integrate color features and texture ones in the matching cost function. In this way, more reliable matches can be found in the stereo matching. Firstly we introduce a new texture descriptor, namely, the multi-layer Local Ternary Patterns (LTP), in the matching cost function. Different from the original LTP, our multi-layer descriptor can represent the pixel as specific as possible. Secondly a recently proposed filtering method called the adaptive manifolds filtering is adopted as the cost aggregation strategy. This filtering is a high-dimensional real-time filter operator, which has been verified to be very effective in many image processing fields while is firstly utilized in stereo matching. Finally experiments conducted in the Middlebury benchmark sufficiently verify the effectiveness of our proposed stereo matching algorithm.","Title: Pedestrian detection from still images based on multi-feature covariances\nYear: 2013\n\nAbstract: This paper targets the detection of pedestrians from still images, which focuses on developing robust feature representations that encode image regions as covariance matrices to support high accuracy pedestrian/non-pedestrian decisions. Firstly we utilize a fast method for computation of covariances based on integral images. By integrating the advantages of both covariance-based object detection and HOG-and FDF-based pedestrian detection, we then introduce four new feature representations for training a pedestrian detector: Covariance-based first-order Histogram of Oriented Gradient (Cov-HOG1), Covariance-based second-order Histogram of Oriented Gradient (Cov-HOG2), Covariance-based first-order Four Directional Features (Cov-FDF1), and Covariance-based second-order Four Directional Features (Cov-FDF2). To test our feature sets, we adopt a relatively simple learning framework that uses LogitBoost algorithm to classify each possible image region as a pedestrian or as a non-pedestrian. The experimental results show that the proposed algorithm obtains satisfactory pedestrian detection performances on the INRIA person datasets as well as images collected from Google and Flickr websites.","Title: Scalable Compact Modeling for On-Chip Passive Elements with Correlated Parameter Extraction and Adaptive Boundary Compression\nYear: 2014\n\nAbstract: Scalable compact models for passive elements are important in the Analog/RF circuit design and optimization. Traditional scalable modeling methods are mainly physical and manual based methods, which usually require deep physical insight and extensive human intervention. In this paper, an automatic scalable compact modeling method for generic passive elements is established. The proposed method is a unified parameter extraction and scalable modeling scheme with novel inner-loop correlated parameter extraction and outer-loop adaptive boundary compression techniques. Experimental results show that both accuracy and scalability have been achieved by the proposed method for industrial inductors and transformers with an acceptable computational cost.","Title: Scale selection based on Moran's I for segmentation of high resolution remotely sensed images\nYear: 2014\n\nAbstract: Image segmentation is a prerequisite for object-based image analysis (OBIA). However, selecting an optimal segmentation scale is often time consuming and needs trial-and-error. This paper presents an unsupervised scale selection method based on the rate of change of a spatial autocorrelation indicator - the global Moran's I for segmentation of high resolution remotely sensed images. It was compared with other two scale selection methods and its effectiveness is validated through both visual analysis and by referencing to multiple manual segmentations. Experimental results on our own data and statistical data from an external reference showed that the optimal scale could be easily selected through the proposed method.","Title: Robust Line Matching Based On Ray-Point-Ray Structure Descriptor\nYear: 2014\n\nAbstract: In this paper, we propose a novel two-view line matching method through converting matching line segments extracted from two uncalibrated images to matching the introduced Ray-Point-Ray (RPR) structures. The method first recovers the partial connectivity of line segments through sufficiently exploiting the gradient map. To efficiently matching line segments, we introduce the Ray-Point-Ray (RPR) structure consisting of a joint point and two rays (line segments) connected to the point. Two sets of RPRs are constructed from the connected line segments extracted from two images. These RPRs are then described with the proposed SIFT-like descriptor for efficient initial matching to recover the fundamental matrix. Based on initial RPR matches and the recovered fundamental matrix, we propose a match propagation scheme consisting of two stages to refine and find more RPR matches. The first stage is to propagate matches among those initially formed RPRs, while the second stage is to propagate matches among newly formed RPRs constructed by intersecting unmatched line segments with those matched ones. In both stages, candidate matches are evaluated by comprehensively considering their descriptors, the epipolar line constraint, and the topological consistency with neighbor point matches. Experimental results demonstrate the good performance of the proposed method as well as its superiority to the state-of-the-art methods.","Title: Estimating Drivable Collision-Free Space from Monocular Video\nYear: 2015\n\nAbstract: In this paper we propose a novel algorithm for estimating the drivable collision-free space for autonomous navigation of on-road and on-water vehicles. In contrast to previous approaches that use stereo cameras or LIDAR, we show a method to solve this problem using a single camera. Inspired by the success of many vision algorithms that employ dynamic programming for efficient inference, we reduce the free space estimation task to an inference problem on a 1D graph, where each node represents a column in the image and its label denotes a position that separates the free space from the obstacles. Our algorithm exploits several image and geometric features based on edges, color, and homography to define potential functions on the 1D graph, whose parameters are learned through structured SVM. We show promising results on the challenging KITTI dataset as well as video collected from boats.","Title: An efficient time step control method in transient simulation for DAE system\nYear: 2014\n\nAbstract: Adaptive time step control is very important or even crucial in transient simulation for the efficiency of a circuit simulator. Existing methods are mainly based on the formula of the local truncation error (LTE) for solving ordinary differential equations (ODEs), which is an approximation for the circuit simulator solving a system of nonlinear differential algebraic equations (DAEs). In this work, we derived the formula of LTE for DAE system and proposed a new time step control method. Experimental results show that the proposed method works well for industrial circuits.","Title: An Efficient SRAM Yield Analysis and Optimization Method With Adaptive Online Surrogate Modeling\nYear: 2015\n\nAbstract: SRAM cells usually require extremely low failure rate or equivalently extremely high production yield, making it impractical to perform yield analysis using Monte Carlo (MC) method as huge amount of samples are needed. Fast MC methods, e.g., importance sampling methods, are still too expensive as the anticipated failure rate is very low. In this paper, a new SRAM yield analysis method is proposed to tackle this issue. The key idea is to improve traditional importance sampling method with an efficient online surrogate model. Experimental results show that the proposed yield analysis method achieves – speedup over existing state-of-the-art techniques without sacrificing estimation accuracy. Sigma distribution and schmoo plot can be quickly generated by the proposed method, which is very useful for realistic applications. Based on the proposed yield analysis method, an efficient yield optimization method has been developed to further automate the SRAM cell design procedure where process variations can be fully considered. Experimental results show that a fully automatic yield optimization for SRAM cells can be done within only a few hours.","Title: Alterations of the human gut microbiome in liver cirrhosis.\nYear: 2014\n\nAbstract: Liver cirrhosis occurs as a consequence of many chronic liver diseases that are prevalent worldwide. Here we characterize the gut microbiome in liver cirrhosis by comparing 98 patients and 83 healthy control individuals. We build a reference gene set for the cohort containing 2.69 million genes, 36.1% of which are novel. Quantitative metagenomics reveals 75,245 genes that differ in abundance between the patients and healthy individuals (false discovery rate < 0.0001) and can be grouped into 66 clusters representing cognate bacterial species; 28 are enriched in patients and 38 in control individuals. Most (54%) of the patient-enriched, taxonomically assigned species are of buccal origin, suggesting an invasion of the gut from the mouth in liver cirrhosis. Biomarkers specific to liver cirrhosis at gene and function levels are revealed by a comparison with those for type 2 diabetes and inflammatory bowel disease. On the basis of only 15 biomarkers, a highly accurate patient discrimination index is created and validated on an independent cohort. Thus microbiota-targeted biomarkers may be a powerful tool for diagnosis of different diseases.","Title: Hierarchical line matching based on Line-Junction-Line structure descriptor and local homography estimation.\nYear: 2016\n\nAbstract: This paper presents a hierarchical method for matching line segments from two images. Line segments are matched first in groups and then in individuals. While matched in groups, the line segments lying adjacently are intersected to form junctions. At the places of the junctions, the structures are constructed called Line–Junction–Line (LJL), which consists of two adjacent line segments and their intersecting junction. To reliably deal with the possible scale change between the two images to be matched, we propose to describe LJLs by a robust descriptor in the multi-scale pyramids of images constructed from two original images. By evaluating the description vector distances of LJLs from the two images, some candidate LJL matches are obtained, which are then refined and expanded by an effective match-propagation strategy. The line segments used to construct LJLs are matched when the LJLs they formed are matched. For those left unmatched line segments, we match them in individuals by utilizing the local homographies estimated from their neighboring matched LJLs. Experiments demonstrate the superiorities of the proposed method to the state-of-the-art methods for its robustness in more difficult situations, the larger amounts of correct matches, and the higher accuracy in most cases.","Title: Accurate Text Localization in Natural Image with Cascaded Convolutional Text Network.\nYear: 2016\n\nAbstract: We introduce a new top-down pipeline for scene text detection. We propose a novel Cascaded Convolutional Text Network (CCTN) that joints two customized convolutional networks for coarse-to-fine text localization. The CCTN fast detects text regions roughly from a low-resolution image, and then accurately localizes text lines from each enlarged region. We cast previous character based detection into direct text region estimation, avoiding multiple bottom- up post-processing steps. It exhibits surprising robustness and discriminative power by considering whole text region as detection object which provides strong semantic information. We customize convolutional network by develop- ing rectangle convolutions and multiple in-network fusions. This enables it to handle multi-shape and multi-scale text efficiently. Furthermore, the CCTN is computationally efficient by sharing convolutional computations, and high-level property allows it to be invariant to various languages and multiple orientations. It achieves 0.84 and 0.86 F-measures on the ICDAR 2011 and ICDAR 2013, delivering substantial improvements over state-of-the-art results [23, 1].","Title: Adaptive Human Behavior Modeling for Air Combat Simulation.\nYear: 2015\n\nAbstract: Military simulations, especially those for personnel training and equipment effectiveness analysis, require proper human behavior models (HBMs) to play blue or red. Traditionally, the HBMs are controlled through rule based scripts. However, the doctrine-driven behavior is rigid and predictable, and more often than not unable to adapt to new situations. In most cases, the subject matter experts (SMEs) review, re-design a large amount of HBM scripts for new scenarios or training tasks, which is challenging and time-consuming. Therefore, a study of using Grammatical Evolution (GE) to generate adaptive HBMs for air combat simulation is conducted in this work. Expert knowledge is encoded with modular behavior trees (BTs) for the compatibility with the operators in genetic algorithm (GA). GE maps HBMs represented with BTs to binary strings, and uses GA to evolve HBMs with the performance fed back from simulation. Beyond visual range air combat experiments between adaptive HBMs and none-adaptive baseline HBMs are conducted to study the evolutionary process. The experimental results show that the GE is an efficient framework to generate adaptive HBMs in BTs formalism and evolve them with GA.","Title: MULTI-CAMERA 3D PERSON TRACKING WITH PARTICLE FILTER IN A SURVEILLANCE ENVIRONMENT\nYear: 2008\n\nAbstract: In this work we present and evaluate a novel 3D approach to track single people in surveillance scenarios, using multiple cameras. The problem is formulated in a Bayesian filtering framework, and solved through sampling approximations (i.e. using a particle fil- ter). Rather than relying on a 2D state to represent people, as is most commonly done, we directly exploit 3D knowledge by track- ing people in the 3D world. A novel dynamical model is presented that accurately models the coupling between people orientation and motion direction. In addition, people are represented by three 3D elliptic cylinders which allow to introduce a spatial color layout useful to discriminate the tracked person from potential distractors. Thanks to the particle filter approach, integrating background sub- traction and color observations from multiple cameras is straight- forward. Alltogether, the approach is quite robust to occlusion and large variations in people appearence, even when using a single camera, as demonstrated by numerical performance evaluation on real and challenging data from an underground station.","Title: Model-architecture oriented combat system effectiveness simulation.\nYear: 2015\n\nAbstract: Combat system effectiveness simulation (CESS) is a special type of complex system simulation. Three non-functional requirements (NFRs), i.e. model composability, domain-specific modeling, and model evolvability are gaining higher priority from CESS users when evaluating different modeling methodologies for CESS. Traditional CESS modeling methodologies are either domain-neutral (lack of domain characteristics consideration and limited support for model composability) or domain-oriented (lack of openness and evolvability) and fall short of the three NFRs. Inspired by the concept of architecture in systems engineering and software engineering fields, we extend it into a concept of model architecture for complex simulation systems, and propose a model-architecture oriented modeling methodology in which model architecture plays a central role in achieving the three NFRs. Various model-driven engineering (MDE) approaches and technologies, including SMP, UML, DSM, and so forth, are applied where possible in representing the CESS model architecture and its components' behaviors from physical and cognitive domain aspects.","Title: Magnetic-Gravity Gradient Inversion For Underwater Object Detection\nYear: 2015\n\nAbstract: A new underwater object detection method based on joint Gravity-Gradient and Magnetic-Gradient Inversion algorithms is proposed in this paper. Magnetic gradient and gravity gradient anomalies induced by an underwater object can be measured and inversed to estimate the relative changes in distance between underwater object and underwater vehicle. The weight least squares estimation is introduced to combine equations of magnetic gradient and gravity gradient inversion. Therefore, the joint inversion method gets an optimal relative position of underwater object using two kinds of data. Simulation results show that the proposed method is more efficient than the previous Joint gravity - gradient tensor inversion and magnetic gradient tensor inversion respectively.","Title: Strong Authentication Scheme Based On Hand Geometry And Smart Card Factors\nYear: 2016\n\nAbstract: In 2009, Xu et al. presented a safe, dynamic, id-based on remote user authentication method that has several advantages such as freely chosen passwords and mutual authentication. In this paper, we review the Xu-Zhu-Feng scheme and indicate many shortcomings in their scheme. Impersonation attacks and insider attacks could be effective. To overcome these drawbacks, we propose a secure biometric-based remote authentication scheme using biometric characteristics of hand-geometry, which is aimed at withstanding well-known attacks and achieving good performance. Furthermore, our work contains many crucial merits such as mutual authentication, user anonymity, freely chosen passwords, secure password changes, session key agreements, revocation by using personal biometrics, and does not need extra device or software for hand geometry in the login phase. Additionally, our scheme is highly efficient and withstands existing known attacks like password guessing, server impersonation, insider attacks, denial of service (DOS) attacks, replay attacks, and parallel-session attacks. Compared with the other related schemes, our work is powerful both in communications and computation costs.","Title: Line Segment Matching: A Benchmark\nYear: 2016\n\nAbstract: As the vital procedure for exploiting line segments extracted from images for solving computer vision problems, Line Segment Matching (LSM) has received growing attentions from researcher in recent years, and a considerable number of methods have been proposed. However, no one has attempted to solve two major problems in this area. The first is how to evaluate different methods in an unbiased way. All proposed methods were evaluated using images and line segment detectors selected by the authors themselves, making the conclusions based on the somewhat biased experiments less convincing. The second problem is that there is no reliably automatic way to access the correctness of obtained line segment matches, which can often be up to hundreds in quantity. Checking them one by one by visual inspection is the only reliable, but very tedious and error-prone way. In this paper, we target to solve the two problems. We introduce a benchmark which provides the ground truth matches among 30 pairs of line segment sets extracted from 15 representative image pairs using two state-of-the-art line segment detectors. With the benchmark, we evaluated some of the existing LSM methods.","Title: Joint Point And Line Segment Matching On Wide-Baseline Stereo Images\nYear: 2016\n\nAbstract: This paper presents an method that matches points and line segments jointly on wide-baseline stereo images. In both two images to be matched, line segments are extracted and those spatially adjacent ones are intersected to generate V-junctions. To match V-junctions from the two images, we extract for each of them an affine and scale invariant local region and describe it with SIFT. The putative V-junction matches obtained from evaluating their description vectors are refined subsequently by the epipolar line constraint and topological distribution constraint among neighbor V-junctions. Since once a pair of V-junctions are matched, the two pairs of line segments forming them are matched accordingly. A part of line segments from the two images are therefore matched along with V-junction matches. To get more line segment matches, we further match those left unmatched line segments by the local homographies estimated from their adjacent V-junction matches. Experiments verify the robustness of the proposed method and its superiority to both some famous point and line segment matching methods on wide-baseline stereo images. In addition, we also show the proposed method can make it easier for 3D line segment reconstruction.","Title: Motion-free exposure fusion based on inter-consistency and intra-consistency.\nYear: 2017\n\nAbstract: Exposure fusion often suffers from ghost artifacts, which are caused by the movement of objects when a dynamic scene is captured. In this paper, two types of consistency concepts are introduced for enforcing the guidance of a reference image for motion detection and ghost removal. Specifically, the inter-consistency, which represents the similarities of pixel intensities among different exposures, is weakened by the use of different exposure settings. Histogram matching is employed to recover the inter-consistency. Following this, pixel differences are mostly the result of changes in content caused by object movements, so motion can easily be detected. To further restrain the weights of outliers in fusion, motion detection is performed at a super-pixel level, to ensure that pixels with similar intensities and structures share similar fusion weights. This is referred to as intra-consistency. Experiments in various dynamic scenes demonstrate that the proposed algorithm can determine the motion more effectively than existing methods, and produce high quality fusion results that are free of ghost artifacts.","Title: A Unified Framework for Street-View Panorama Stitching.\nYear: 2017\n\nAbstract: In this paper, we propose a unified framework to generate a pleasant and high-quality street-view panorama by stitching multiple panoramic images captured from the cameras mounted on the mobile platform. Our proposed framework is comprised of four major steps: image warping, color correction, optimal seam line detection and image blending. Since the input images are captured without a precisely common projection center from the scenes with the depth differences with respect to the cameras to different extents, such images cannot be precisely aligned in geometry. Therefore, an efficient image warping method based on the dense optical flow field is proposed to greatly suppress the influence of large geometric misalignment at first. Then, to lessen the influence of photometric inconsistencies caused by the illumination variations and different exposure settings, we propose an efficient color correction algorithm via matching extreme points of histograms to greatly decrease color differences between warped images. After that, the optimal seam lines between adjacent input images are detected via the graph cut energy minimization framework. At last, the Laplacian pyramid blending algorithm is applied to further eliminate the stitching artifacts along the optimal seam lines. Experimental results on a large set of challenging street-view panoramic images captured form the real world illustrate that the proposed system is capable of creating high-quality panoramas.","Title: Learning to Refine Object Contours with a Top-Down Fully Convolutional Encoder-Decoder Network.\nYear: 2017\n\nAbstract: We develop a novel deep contour detection algorithm with a top-down fully convolutional encoder-decoder network. Our proposed method, named TD-CEDN, solves two important issues in this low-level vision problem: (1) learning multi-scale and multi-level features; and (2) applying an effective top-down refined approach in the networks. TD-CEDN performs the pixel-wise prediction by means of leveraging features at all layers of the net. Unlike skip connections and previous encoder-decoder methods, we first learn a coarse feature map after the encoder stage in a feedforward pass, and then refine this feature map in a top-down strategy during the decoder stage utilizing features at successively lower layers. Therefore, the deconvolutional process is conducted stepwise, which is guided by Deeply-Supervision Net providing the integrated direct supervision. The above proposed technologies lead to a more precise and clearer prediction. Our proposed algorithm achieved the state-of-the-art on the BSDS500 dataset (ODS F-score of 0.788), the PASCAL VOC2012 dataset (ODS F-score of 0.588), and and the NYU Depth dataset (ODS F-score of 0.735).","Title: Globally consistent alignment for planar mosaicking via topology analysis.\nYear: 2017\n\nAbstract: In this paper, we propose a generic framework for globally consistent alignment of images captured from approximately planar scenes via topology analysis, capable of resisting the perspective distortion meanwhile preserving the local alignment accuracy. Firstly, to estimate the topological relations of images efficiently, we search for a main chain connecting all images over a fast built similarity table of image pairs (mainly for the unordered image sequence), along which the potential overlapping pairs are incrementally detected according to the gradually recovered geometric positions and orientations. Secondly, all the sequential images are organized as a spanning tree through applying a graph algorithm on the topological graph, so as to find the optimal reference image which minimizes the total number of error propagation. Thirdly, the global alignment under topology analysis is performed in the strategy that images are initially aligned by groups via the affine model, followed by the homography refinement under the anti-perspective constraint, which manages to keep the optimal balance between aligning precision and global consistency. Finally, experimental results on two challenging aerial image sets illustrate the superiority of the proposed approach. HighlightsA generic framework for mosaicking (ordered and unordered) images captured from an approximately planar scene is proposed.Method finding a valid main chain of unordered images efficiently by the Minimum Spanning Tree (MST) algorithm is proposed.A global alignment strategy able to keep an optimal balance between global consistency and aligning accuracy is proposed.","Title: 2-Line Exhaustive Searching for Real-Time Vanishing Point Estimation in Manhattan World\nYear: 2017\n\nAbstract: This paper presents a very simple and efficient algorithm to estimate 1, 2 or 3 orthogonal vanishing point(s) on a calibrated image in Manhattan world. Unlike the traditional methods which apply 1, 3, 4, or 6 line(s) to generate vanishing point hypotheses, we propose to use 2 lines to get the first vanishing point v1, then uniformly take sample of the second vanishing point v2 on the great circle of v1 on the equivalent sphere, and finally calculate the third vanishing point v3 by the cross-product of v1 and v2. There are three advantages of the proposed method over traditional multi-line method. First, the 2-line model is much more robust and reliable than the multi-line method, which can be applied in the scene with 1, 2 or 3 orthogonal vanishing point(s). Second, the probability of the 2-line model being formed of inner line segments can be calculated given the outlier ratio, which means that the number of iterations can be determined, and thus the estimation of vanishing points can be performed in a very simple exhaustive way instead of the traditional RANSAC method. Third, the real-time performance is achieved by building a polar grid for the line intersection points, which functions as a lookup table for the validation of vanishing point hypotheses. Our algorithm has been validated successfully in the YUD dataset and sets of challenging real images.","Title: Optimal Seamline Detection for Orthoimage Mosaicking by Combining Deep Convolutional Neural Network and Graph Cuts.\nYear: 2017\n\nAbstract: When mosaicking orthoimages, especially in urban areas with various obvious ground objects like buildings, roads, cars or trees, the detection of optimal seamlines is one of the key technologies for creating seamless and pleasant image mosaics. In this paper, we propose a new approach to detect optimal seamlines for orthoimage mosaicking with the use of deep convolutional neural network (CNN) and graph cuts. Deep CNNs have been widely used in many fields of computer vision and photogrammetry in recent years, and graph cuts is one of the most widely used energy optimization frameworks. We first propose a deep CNN for land cover semantic segmentation in overlap regions between two adjacent images. Then, the energy cost of each pixel in the overlap regions is defined based on the classification probabilities of belonging to each of the specified classes. To find the optimal seamlines globally, we fuse the CNN-classified energy costs of all pixels into the graph cuts energy minimization framework. The main advantage of our proposed method is that the pixel similarity energy costs between two images are defined using the classification results of the CNN based semantic segmentation instead of using the image informations of color, gradient or texture as traditional methods do. Another advantage of our proposed method is that the semantic informations are fully used to guide the process of optimal seamline detection, which is more reasonable than only using the hand designed features defined to represent the image differences. Finally, the experimental results on several groups of challenging orthoimages show that the proposed method is capable of finding high-quality seamlines among urban and non-urban orthoimages, and outperforms the state-of-the-art algorithms and the commercial software based on the visual comparison, statistical evaluation and quantitative evaluation based on the structural similarity (SSIM) index.","Title: Optimal seamline detection in dynamic scenes via graph cuts for image mosaicking.\nYear: 2017\n\nAbstract: In this paper, we present a novel method for creating a seamless mosaic from a set of geometrically aligned images captured from the scene with dynamic objects at different times. The artifacts caused by dynamic objects and geometric misalignments can be effectively concealed in our proposed seamline detection algorithm. In addition, we simultaneously compensate the image regions of dynamic objects based on the optimal seamline detection in the graph cuts energy minimization framework and create the mosaic with a relatively clean background. To ensure the high quality of the optimal seamline, the energy functions adopted in graph cuts combine the pixel-level similarities of image characteristics, including intensity and gradient, and the texture complexity. To successfully compensate the image regions covered by dynamic objects for creating a mosaic with a relatively clean background, we initially detect them in overlap regions between images based on pixel-level and region-level similarities, then refine them based on segments, and determine their image source in probability based on contour matching. We finally integrate all of these into the energy minimization framework to detect optimal seamlines. Experimental results on different dynamic scenes demonstrate that our proposed method is capable of generating high-quality mosaics with relatively clean backgrounds based on the detected optimal seamlines.","Title: Low-Cost High-Accuracy Variation Characterization For Nanoscale Ic Technologies Via Novel Learning-Based Techniques\nYear: 2018\n\nAbstract: Faster and more accurate variation characterizations of semiconductor devices/circuits are in great demand as process technologies scale down to Fin-FET era. Traditional methods with intensive data testing are extremely costly. In this paper, we propose a novel learning-based high-accuracy data prediction framework inspired by learning methods from computer vision to efficiently characterize variabilities of device/circuit behaviors induced by manufacturing process variations. The key idea is to adaptively learn the underlying data pattern among data with variations from a small set of already obtained data and utilize it to accurately predict the unmeasured data with minimum physical measurement cost. To realize this idea, novel regression modeling techniques based on Gaussian process regression and partial least squares regression with feature extraction and matching are developed. We applied our approach to real-time variation characterization for transistors with multiple geometries from a foundry 28nm CMOS process. The results show that the framework achieves about 14x time speed-up with on average 0.1 A error for variation data prediction and under 0.3% error for statistical extraction compared to traditional physical measurements, which demonstrates the efficacy of the framework for accurate and fast variation analysis and statistical modeling.","Title: Fine-grained Video Attractiveness Prediction Using Multimodal Deep Learning on a Large Real-world Dataset.\nYear: 2018\n\nAbstract: Nowadays, billions of videos are online ready to be viewed and shared. Among an enormous volume of videos, some popular ones are widely viewed by online users while the majority attract little attention. Furthermore, within each video, different segments may attract significantly different numbers of views. This phenomenon leads to a challenging yet important problem, namely fine-grained video attractiveness prediction, which only relies on video contents to forecast video attractiveness at fine-grained levels, specifically video segments of several second length in this paper. However, one major obstacle for such a challenging problem is that no suitable benchmark dataset currently exists. To this end, we construct the first fine-grained video attractiveness dataset (FVAD), which is collected from one of the most popular video websites in the world. In total, the constructed FVAD consists of 1,019 drama episodes with 780.6 hours covering different categories and a wide variety of video contents. Apart from the large amount of videos, hundreds of millions of user behaviors during watching videos are also included, such as view counts, \"fast-forward, \"fast-rewind, and so on, where \"view counts\" reflects the video attractiveness while other engagements capture the interactions between the viewers and videos. First, we demonstrate that video attractiveness and different engagements present different relationships. Second, FVAD provides us an opportunity to study the fine-grained video attractiveness prediction problem. We design different sequential models to perform video attractiveness prediction by relying solely on video contents. The sequential models exploit the multimodal relationships between visual and audio components of the video contents at different levels. Experimental results demonstrate the effectiveness of our proposed sequential models with different visual and audio representations, the necessity of incorporating the two modalities, and the complementary behaviors of the sequential prediction models at different levels.","Title: Edge-Enhanced Optimal Seamline Detection for Orthoimage Mosaicking.\nYear: 2018\n\nAbstract: In this letter, we propose a novel algorithm to detect the optimal seamline by using the edge-enhanced energy function for orthoimage mosaicking. First, we generate the energy cost map by using traditional intensity and gradient difference. Then, to ensure that the detected optimal seamlines avoid crossing the obvious objects, the energy map is enhanced in the regions of valid edge segments around...","Title: Tactics Exploration Framework Based On Genetic Programming\nYear: 2017\n\nAbstract: Engagement-level simulation is a quantitative way to evaluate the effectiveness of weapon systems before construction and acquisition, minimizing the risk of investment. Though contractors have built simulation systems with high fidelity models of weapon systems and battlefields, developing competent tactics to give full play to new weapon systems in simulation experiments is labor intensive, as most classical tactics tend to be out of date. In this work, we proposed a tactics exploration framework (TEF) that applied grammar-based genetic programming (GP) to generating and evolving tactics in the engagement-level simulation. Tactics are represented with modular behavior trees (BTs) for compatibility with the genetic operators. Experiments to explore submarine tactics have been conducted to observe and study the exploration process. The experimental results show that the TEF based on GP is efficient to explore tactics in the formalism of BTs.","Title: Relaxed two points projection method for solving the multiple-sets split equality problem.\nYear: 2018\n\nAbstract: The multiple-sets split equality problem, a generalization and extension of the split feasibility problem, has a variety of specific applications in real world, such as medical care, image reconstruction, and signal processing. It can be a model for many inverse problems where constraints are imposed on the solutions in the domains of two linear operators as well as in the operators’ ranges simultaneously. Although, for the split equality problem, there exist many algorithms, there are but few algorithms for the multiple-sets split equality problem. Hence, in this paper, we present a relaxed two points projection method to solve the problem; under some suitable conditions, we show the weak convergence and give a remark for the strong convergence method in the Hilbert space. The interest of our algorithm is that we transfer the problem to an optimization problem, then, based on the model, we present a modified gradient projection algorithm by selecting two different initial points in different sets for the problem (we call the algorithm as two points algorithm). During the process of iteration, we employ subgradient projections, not use the orthogonal projection, which makes the method implementable. Numerical experiments manifest the algorithm is efficient.","Title: Generalized Content-Preserving Warps for Image Stitching.\nYear: 2018\n\nAbstract: Local misalignment caused by global homography is a common issue in image stitching task. Content-Preserving Warping (CPW) is a typical method to deal with this issue, in which geometric and photometric constraints are imposed to guide the warping process. One of its essential condition however, is colour consistency, and an elusive goal in real world applications. In this paper, we propose a Generalized Content-Preserving Warping (GCPW) method to alleviate this problem. GCPW extends the original CPW by applying a colour model that expresses the colour transformation between images locally, thus meeting the photometric constraint requirements for effective image stitching. We combine the photometric and geometric constraints and jointly estimate the colour transformation and the warped mesh vertexes, simultaneously. We align images locally with an optimal grid mesh generated by our GCPW method. Experiments on both synthetic and real images demonstrate that our new method is robust to colour variations, outperforming other state-of-the-art CPW-based image stitching methods.","Title: Subtracted Histogram: Utilizing Mutual Relation Between Features for Thresholding.\nYear: 2018\n\nAbstract: In this paper, we propose a thresholding method utilizing the mutual relation between the two used features, which should be both robust and of low correlation. The mutual relation is exploited through a histogram subtraction transformation, which tries to reduce only the background part of each of the histograms for the features so that we can easily differentiate between the background part and ...","Title: Single Image Haze Removal via Joint Estimation of Detail and Transmission\nYear: 2018\n\nAbstract: Single image haze removal is an important task in computer vision. However, haze removal is an extremely challenging problem due to it is massively ill-posed, which is that we need to estimate the transmission and the corresponding haze-free pixel from a single color measurement at each pixel. In this paper, we propose a new deep learning based method for removing haze from single input image. First, we estimate a transmission map via joint estimation of clear image details and transmission map, which is different from traditional methods which only estimating a transmission map for a hazy image. Second, we use a global regularization method to eliminate the halos and artifacts. Experimental results demonstrate that our method outperforms the other state-of-the-art dehazing methods.","Title: Video Stitching With Extended-Meshflow\nYear: 2018\n\nAbstract: In this paper, we present a method that stitches multiple videos captured with a fixed camera rig. We propose an Extended-MeshFlow motion model for video stitching. Firstly, uniform features are detected and matched at the overlapping region, from which the Exended-MeshFlow model is estimated. The model then warps the adjacent views to the common central view to eliminate the spatial misalignment. The motions located on the feature positions are interpolated to the mesh vertexes by Multilevel B-Spline Approximation(MBA). Collecting the motions on the vertexes form the vertex profiles, which are smoothed for temporal consistency. During the smoothing, only previous frames are required, thus the proposed method can stitch videos in an online mode. Experimental results on various of videos demonstrate that the proposed method can produce comparable stitching results in aspects of spatial alignment and temporal coherence.","Title: Generalized Content-Preserving Warp: Direct Photometric Alignment Beyond Color Consistency.\nYear: 2018\n\nAbstract: Motion estimation is vital in many computer vision applications. Most existing methods require high quality and large quantity of feature correspondence and may fail for images with few textures. In this paper, a photometric alignment method is proposed to obtain better motion estimation result. Since the adopted photometric constraints are usually limited to the required illumination or color consistency assumption, a new generalized content-preserving warp (GCPW) framework, therefore, is designed to perform photometric alignment beyond color consistency. Similar to conventional content-preserving warp (CPW), GCPW is also a mesh-based framework, but it extends CPW by appending a local color transformation model for every mesh quad, which expresses the color transformation from a source image to a target image within the quad. Motion-related mesh vertexes and color-related mapping parameters are optimized jointly in GCPW to get more robust motion estimation results. Evaluation of tens of videos reveals that the proposed method achieves more accurate motion estimation results. More importantly, it is robust to significant color variation. Besides, this paper explores the performance of GCPW in two popular computer vision applications: image stitching and video stabilization. Experimental results demonstrate GCPW's effectiveness in dealing with typical challenging scenes for these two applications.","Title: Robust Camera Pose Estimation Via Consensus On Ray Bundle And Vector Field\nYear: 2018\n\nAbstract: Estimating the camera pose requires point correspondences. However, in practice, correspondences are inevitably corrupted by outliers, which affects the pose estimation. We propose a general and accurate outlier removal strategy for robust camera pose estimation. The proposed strategy can detect outliers by leveraging the fact that only inliers comply with two effective consensuses, i.e., 3D ray bundle consensus and 2D vector field consensus. Our strategy has a nested structure. First, the outer module utilizes the 3D ray bundle consensus. We define the likelihood based on the probabilistic mixture model and maximize it by the expectation-maximization (EM) algorithm. The inlier probability of each correspondence and the camera pose are determined alternately. Second, the inner module exploits the 2D vector field consensus to refine the probabilities obtained by the outer module. The refinement based on the Bayesian rule facilitates the convergence of the outer module and improves the accuracy of the entire framework. Our strategy can be integrated into various existing camera pose estimation methods which are originally vulnerable to outliers. Experiments on both synthesized data and real images have shown that our approach outperforms state-of-the-art outlier rejection methods in terms of accuracy and robustness.","Title: Evaluation Model of the Artist Based on Fuzzy Membership to Improve the Principal Component Analysis of Robust Kernel\nYear: 2016\n\nAbstract: Principal component analysis is a number of related indexes into a multivariate statistical method a fewrelated indicators, often used in data compression and feature extraction are widely used in industry, agriculture, economy, biology, medicine, astronomy, geography and other fields. In the classical principal component analysis, each training data in construction the main ingredient is the same. However, in many practical problems, the significance and effect of the training data is different, usually some of the data than other data is moreimportant. We should pay more attention to the important data, should play a greater role in the construction of the main components, and the data may be not credible is the abnormal data, should limit its role. In this paper, each training data gives a confidence weight to the training data as fuzzy points in the sample space, based on the research Principal component analysis and kernel principal component analysis of fuzzy point data. In this paper, an analysis method based on the principal component analysis of the objective weight is presented, and the method is applied to the evaluation of the value of the artist's creation. The paper analyses the in kernel principal component analysis KPCA, input data space X reflect the shoot diameter: R P, h is projected onto a new high-dimensional feature space h after, although you can achieve nonlinear feature extraction, but still in the presence of outliers. In feature space, we can reduce the effect of outliers, and avoid the effect of the traditionalprinciple component analysis, so it has the advantages of robust and nonlinear. In fact, we show that the fuzzy membership degree of fuzzy membership degree is improved, and the accuracy rate is 84%.We use the kernel principal component analysis method to improve the original foundation, and realize the construction of the artist evaluation model, and improve the accuracy.","Title: Superpixel-Based Optimal Seamline Detection Via Graph Cuts For Panoramic Images\nYear: 2016\n\nAbstract: In this paper, we present a novel method for seamlessly mosaicking panoramic images based on superpixels in the graph cuts energy minimization framework. To effectively ensure that all seamlines are detected in the laterally continuous regions with the high image similarity and the low object dislocation, the energy functions adopted in graph cuts combine the pixel-level similarities of image characteristics, including intensity and gradient, and the texture complexity. Instead of finding the optimal solution of seamlines in overlap regions via graph cuts among the entire set of pixels, we find it among superpixels created from input images, which greatly improves the efficiency of the global graph cuts energy optimization because the number of elements in graph cuts dramatically decreases. Experimental results demonstrate that the superpixel-based method is capable of generating high-quality seamlines as the pixel-based method but greatly reduces the computation time.","Title: 3d Line Segment Reconstruction In Structured Scenes Via Coplanar Line Segment Clustering\nYear: 2016\n\nAbstract: This paper presents a new algorithm aiming for 3D Line Segment (LS) reconstruction in structured scenes that are comprised of a set of planes. Due to location imprecision of image LSs, it often produces many erroneous reconstructions when reconstructing 3D LSs by triangulating corresponding LSs from two images. We propose to solve this problem by first recovering space planes and then back-projecting image LSs onto the recovered space planes to get reliable 3D LSs. Given LS matches identified from two images, we estimate a set of planar homographies and use them to cluster the LS matches into groups such that LS matches in each group are related by the same homography induced by a space plane. In each LS match group, the corresponding space plane can be recovered from the 3D LSs obtained by triangulating all the LS correspondences. To reduce the incidence of incorrect LS match grouping, we formulate to solve the LS match grouping problem into solving a multi-label optimization problem. The advantages of the proposed algorithm over others in this area are that it can generate more complete and detailed 3D models of scenes using much fewer images and can recover the space planes where the reconstructed 3D LSs lie, which is beneficial for upper level applications, like scene understanding and building facade extraction.","Title: Multi-Oriented and Scale-Invariant License Plate Detection Based on Convolutional Neural Networks.\nYear: 2019\n\nAbstract: License plate detection (LPD) is the first and key step in license plate recognition. State-of-the-art object-detection algorithms based on deep learning provide a promising form of LPD. However, there still exist two main challenges. First, existing methods often enclose objects with horizontal rectangles. However, horizontal rectangles are not always suitable since license plates in images are multi-oriented, reflected by rotation and perspective distortion. Second, the scale of license plates often varies, leading to the difficulty of multi-scale detection. To address the aforementioned problems, we propose a novel method of multi-oriented and scale-invariant license plate detection (MOSI-LPD) based on convolutional neural networks. Our MOSI-LPD tightly encloses the multi-oriented license plates with bounding parallelograms, regardless of the license plate scales. To obtain bounding parallelograms, we first parameterize the edge points of license plates by relative positions. Next, we design mapping functions between oriented regions and horizontal proposals. Then, we enforce the symmetry constraints in the loss function and train the model with a multi-task loss. Finally, we map region proposals to three edge points of a nearby license plate, and infer the fourth point to form bounding parallelograms. To achieve scale invariance, we first design anchor boxes based on inherent shapes of license plates. Next, we search different layers to generate region proposals with multiple scales. Finally, we up-sample the last layer and combine proposal features extracted from different layers to recognize true license plates. Experimental results have demonstrated that the proposed method outperforms existing approaches in terms of detecting license plates with different orientations and multiple scales.","Title: Single Image Dehazing Using Deep Convolution Neural Networks.\nYear: 2017\n\nAbstract: Haze removal is urgently desired in multi-media system. A deep learning-based method, called dehazingCNN, is proposed to estimate an approximate clear image. The proposed learning model is different from traditional learning based method. We adopts Deep Convolution Neural Networks (CNN) to take a hazy image as the input and outputs the corresponding clear image directly. The output of the network is high quality except some block artifacts and color distortions. We can remove the color distortion in the approximate clear image via atmospheric scattering model and guided filter effectively. Experimental results on different type of images, such as synthetic and benchmark of hazy images, demonstrate that the proposed method is comparative to and even better than many complex state-of-the-art methods.","Title: Multiple Combined Constraints For Image Stitching\nYear: 2018\n\nAbstract: Several approaches to image stitching use different constraints to estimate the motion model between image pairs. These constraints can be roughly divided into two categories: geometric constraints and photometric constraints. In this paper, geometric and photometric constraints are combined to improve the alignment quality, which is based on the observation that these two kinds of constraints are complementary. On the one hand, geometric constraints (e.g., point and line correspondences) are usually spatially biased and are insufficient in some extreme scenes, while photometric constraints are always evenly and densely distributed. On the other hand, photometric constraints are sensitive to displacements and are not suitable for images with large parallaxes, while geometric constraints are usually imposed by feature matching and are more robust to handle parallaxes. The proposed method therefore combines them together in an efficient mesh-based image warping framework. It achieves better alignment quality than methods only with geometric constraints, and can handle larger parallax than photometric-constraint-based method. Experimental results on various images illustrate that the proposed method outperforms representative state-of-the-art image stitching methods reported in the literature.","Title: Feed-Net: Fully End-to-End Dehazing.\nYear: 2018\n\nAbstract: This paper proposes an image dehazing model built with a fully convolutional neural network (CNN), called Fully End-to-End Dehazing Network (FEED-Net). In contrast to estimate the transmission map and the atmospheric light separately as most previous deep learning methods, FEED-Net recovers the hazy-free image directly from a hazy image via a light-weight CNN. In addition, we introduce contextual information into dehazing via dilated convolution and use dense skip connection for feature fusion, which makes end-to-end dehazing possible. Experimental results show our method outperforms the state-of-the-art algorithms on both synthetic dataset and real-world images.","Title: RoadNet: Learning to Comprehensively Analyze Road Networks in Complex Urban Scenes from High-Resolution Remotely Sensed Images\nYear: 2019\n\nAbstract: It is a classical task to automatically extract road networks from very high-resolution (VHR) images in remote sensing. This paper presents a novel method for extracting road networks from VHR remotely sensed images in complex urban scenes. Inspired by image segmentation, edge detection, and object skeleton extraction, we develop a multitask convolutional neural network (CNN), called RoadNet, to simultaneously predict road surfaces, edges, and centerlines, which is the first work in such field. The RoadNet solves seven important issues in this vision problem: 1) automatically learning multiscale and multilevel features [gained by the deeply supervised nets (DSN) providing integrated direct supervision] to cope with the roads in various scenes and scales; 2) holistically training the mentioned tasks in a cascaded end-to-end CNN model; 3) correlating the predictions of road surfaces, edges, and centerlines in a network model to improve the multitask prediction; 4) designing elaborate architecture and loss function, by which the well-trained model produces approximately single-pixel width road edges/centerlines without nonmaximum suppression postprocessing; 5) cropping and bilinear blending to deal with the large VHR images with finite-computing resources; 6) introducing rough and simple user interaction to obtain desired predictions in the challenging regions; and 7) establishing a benchmark data set which consists of a series of VHR remote sensing images with pixelwise annotation. Different from the previous works, we pay more attention to the challenging situations, in which there are lots of shadows and occlusions along the road regions. Experimental results on two benchmark data sets show the superiority of our proposed approaches.","Title: DeepCrack: A deep hierarchical feature learning architecture for crack segmentation.\nYear: 2019\n\nAbstract: Automatic crack detection from images of various scenes is a useful and challenging task in practice. In this paper, we propose a deep hierarchical convolutional neural network (CNN), called as DeepCrack, to predict pixel-wise crack segmentation in an end-to-end method. DeepCrack consists of the extended Fully Convolutional Networks (FCN) and the Deeply-Supervised Nets (DSN). During the training, the elaborately designed model learns and aggregates multi-scale and multi-level features from the low convolutional layers to the high-level convolutional layers, which is different from the standard approaches of only using the last convolutional layer. DSN provides integrated direct supervision for features of each convolutional stage. We apply both guided filtering and Conditional Random Fields (CRFs) methods to refine the final prediction results. A benchmark dataset consisting of 537 images with manual annotation maps are built to verify the effectiveness of our proposed method. Our method achieved state-of-the-art performances on the proposed dataset (mean I/U of 85.9, best F-score of 86.5, and 0.1 s per image).","Title: Joint learning of image detail and transmission map for single image dehazing\nYear: 2020\n\nAbstract: Single image haze removal is an important task in computer vision. However, haze removal is an extremely challenging problem due to its massively ill-posed, which is that at each pixel we must estimate the transmission and the global atmospheric light from a single color measurement. In this paper, we propose a new deep learning-based method for removing haze from single input image. First, we estimate a transmission map via joint estimation of clear image detail and transmission map, which is different from traditional methods only estimating a transmission map for a hazy image. Second, we use a global regularization method to eliminate the halos and artifacts. Experimental results on synthetic dataset and real-world images show our method outperforms the other state-of-the-art methods.","Title: Cooperative Data Sharing for Mobile Cloudlets under Heterogeneous Environments\nYear: 2019\n\nAbstract: As accessing remote cloud via cellular network is costly due to the lower bandwidth, higher wide area network (WAN) latency, and higher energy consumption, mobile cloudlet that formed by several edge mobile devices has become an emerging computing paradigm and attracted increasing attention recently. Being different from the existing studies that mainly focus on the issue of computation offloading...","Title: SeeIME: a Chinese mobile IME for Chinese learners based on hybrid Pinyin code\nYear: 2019\n\nAbstract: For foreign Chinese learners, learning Pinyin is much easier than Chinese characters. Traditional Chinese input methods (IMEs) that are intended for Chinese people are not suitable for Chinese learners whose mother language is non-Chinese. In general, different languages can be translated into each other. By this feature and the relevant knowledge of existing IMEs, we take Chinese and English as an example to propose a hybrid encoding that combines Pinyin and the first two letters of its translation. We implement SeeIME with this hybrid Pinyin code. SeeIME can effectively reduce the number of candidate words and help users recognize Chinese characters better via a three-block display method. Using this code for sentence generation can improve the hit rate, which increases from 58% to 84%. The implemented IME is already available for the Android system.","Title: The Realization Of Load Balancing Algorithm In Cloud Computing\nYear: 2018\n\nAbstract: Due(1) to the large number, the length and the processing time of cloud tasks, the cloud task scheduling is unbalanced and it has the problem that the cloud computing service response will be delayed and inefficient in the cloud computing environment. This paper mainly studies the bee colony load balancing algorithm(BCLB) and establishes the mathematical model of the bee colony load balancing algorithm. The mathematical model of the Bee colony balancing algorithm is established and applied in cloud computing. It designs the algorithm implementation process and cloud task scheduling scheme. Finally, through the simulation in the CloudSim, the application of bee colony load balancing algorithm is realized in cloud computing, the experiments show that the BCLB algorithm has greater advantages than random algorithms and greedy load balancing algorithm.","Title: The Research And Implementation Of Middleware In Cloud Computing\nYear: 2018\n\nAbstract: In order to ensure(1) the security and reliability of cloud computing services, this paper uses the advantages of middleware in processing heterogeneous systems to establish a cloud middleware model. It realizes the organic combination of software platform and infrastructure platform and proposes a load balancing mechanism based on middleware. It determines the weights of various parameters based on the middleware load conditions and proposes a load balancing algorithm in middleware. It achieves more granular load balancing and ensures the security of cloud services. Finally, a cloud computer distributed system simulation platform is established. The experimental simulation shows that the middleware load balancing mechanism has good performance in cloud load balancing.","Title: VIC-Net: Voxelization Information Compensation Network for Point Cloud 3D Object Detection\nYear: 2021\n\nAbstract: Voxel-based methods have been widely used in point cloud 3D object detection. These methods usually transform points into voxels while suffering from information loss during point cloud voxelization. To address this problem, we propose a novel one-stage Voxelization Information Compensation Network (VIC-Net), which has the ability of loss-free feature extraction. The whole framework consists of a point branch for geometry detail extraction and a voxel branch for efficient proposals generation. Firstly, PointNet++ is adopted to efficiently encode geometry structure features from the raw point clouds. Then based on the encoded point features, two Point2Voxel (P2V) feature fusion modules are proposed to fuse point features with a voxel backbone, including Local P2V and Multi-Scale P2V. The P2V modules respectively integrate local detail features and multi-scale semantic contexts into a sparse voxel backbone. Thirdly, an auxiliary reconstruction loss is employed on the point branch to explicitly guide the point backbone to be aware of real geometry structures. In addition, we extend VIC-Net to a two-stage approach, namely VIC-RCNN, which further utilizes the fine geometry features to refine object locations. Experiments on the KITTI dataset demonstrate that our proposed VIC-Net outperforms other one-stage methods and our two-stage method VIC-RCNN achieves new state-of-the-art performance.","Title: Multi-scale retinex-based adaptive gray-scale transformation method for underwater image enhancement\nYear: 2022\n\nAbstract: Underwater images play an irreplaceable role as one of the carriers of underwater information acquisition. Underwater degraded images are usually affected by the color cast, noise, and blurred details, which are difficult to apply to various vision tasks. We propose a multi-scale retinex adaptive grayscale transformation underwater image enhancement method, which includes three parts: color correction, image denoising, and detail enhancement. Firstly, the multi-scale Retinex algorithm is adopted to extract the lighting components. Mean and mean square errors were introduced through linear quantization, and color recovery factors were adopted to adjust the three channels for color correction. Second, by treating the image as an anisotropic thermal field diffusing in all direction,image noise is eliminated and edge details are preserved. Finally, for different underwater degraded images, a simulated annealing optimization algorithm is introduced to perform adaptive gray-scale transformation on the image to enhance image details. The results show that the proposed method can comprehensively solve the problems of color distortion, noise, and low contrast. Compared with the state-of-the-art underwater image enhancement and restoration methods, our method has achieved better visual effects.","Title: JPV-Net: Joint Point-Voxel Representations for Accurate 3D Object Detection.\nYear: 2022\n\nAbstract: Voxel and point representations are widely applied in recent 3D object detection tasks from LiDAR point clouds. Voxel representations contribute to efficiently and rapidly locating objects, whereas point representations are capable of describing intra-object spatial relationship for detection refinement. In this work, we aim to exploit the strengths of both two representations, and present a novel two-stage detector, named Joint Point-Voxel Network (JPV-Net). Specifically, our framework is equipped with a Dual Encoders-Fusion Decoder, which consists of the dual encoders to extract voxel features of sketchy 3D scenes and point features rich in geometric context, respectively, and the Feature Propagation Fusion (FP-Fusion) decoder to attentively fuse them from coarse to fine. By making use of the advantages of these features, the refinement network can effectively eliminate false detection and provide better accuracy. Besides, to further develop the perception characteristics of voxel CNN and point backbone, we design two novel intersection-over-union (IoU) estimation modules for proposal generation and refinement, both of which can alleviate the misalignment between the localization and the classification confidence. Extensive experiments on the KITTI dataset and ONCE dataset demonstrate that our proposed JPV-Net outperforms other state-of-the-art methods with remarkable margins.","Title: Practical Issues and Challenges in CSI-based Integrated Sensing and Communication\nYear: 2022\n\nAbstract: Next-generation mobile communication network (i.e., 6G) has been envisioned to go beyond classical communication functionality and provide integrated sensing and communication (ISAC) capability to enable more emerging applications, such as smart cities, connected vehicles, AIoT and health care/elder care. Among all the ISAC proposals, the most practical and promising approach is to empower existing wireless network (e.g., WiFi, 4G/5G) with the augmented ability to sense the surrounding human and environment, and evolve wireless communication networks into intelligent communication and sensing network (e.g., 6G). In this paper, based on our experience on CSI-based wireless sensing with WiFi/4G/5G signals, we intend to identify ten major practical and theoretical problems that hinder real deployment of ISAC applications, and provide possible solutions to those critical challenges. Hopefully, this work will inspire further research to evolve existing WiFi/4G/5G networks into next-generation intelligent wireless network (i.e., 6G).","Title: Global Color Consistency Correction for Large-Scale Images in 3-D Reconstruction\nYear: 2022\n\nAbstract: Global color consistency correction for multiview images in three-dimensional (3-D) reconstruction is an important problem. The color differences between the images will affect the result of dense matching, thereby reducing the geometric accuracy of the mesh model. Moreover, it will also affect the result of texture mapping, causing color differences in the textured model. The color correction method based on global optimization is mainly used to solve this problem. And existing methods usually use sparse matching points as the color correspondences, but the correction results are not accurate enough as a result of the sparsity of the points. Besides, their efficiency of solving large-scale images globally is low. This article proposes a novel color correction method to eliminate the color differences between large-scale multiview images effectively. The core idea of our method is to group images by graph partition algorithm, and then perform intragroup correction and intergroup correction in sequence. First, for each pair of images, we calculate the reliable matching regions around the sparse points as the color correspondences according to the local homography principle. Compared with sparse matching points, our strategy can achieve more accurate color correction results. Next, for large-scale images, we partition them into many groups. For each group of images, the correction parameters are solved to eliminate the color differences of the images included in the group. Finally, we eliminate the color differences between groups by intergroup correction to achieve overall color consistency. Experimental results on typical datasets demonstrate that the proposed method is better than the current representative methods. The proposed method shows better color consistency in the extreme cases, and also exhibits higher computational efficiency on large-scale image sets.","Title: Research and Implementation of Fast-LPRNet Algorithm for License Plate Recognition\nYear: 2021\n\nAbstract: The license plate recognition is an important part of the intelligent traffic management system, and the application of deep learning to the license plate recognition system can effectively improve the speed and accuracy of recognition. Aiming at the problems of traditional license plate recognition algorithms such as the low accuracy, slow speed, and the recognition rate being easily affected by the environment, a Convolutional Neural Network- (CNN-) based license plate recognition algorithm-Fast-LPRNet is proposed. This algorithm uses the nonsegment recognition method, removes the fully connected layer, and reduces the number of parameters. The algorithm-which has strong generalization ability, scalability, and robustness-performs license plate recognition on the FPGA hardware. Increaseing the depth of network on the basis of the Fast-LPRNet structure, the dataset of Chinese City Parking Dataset (CCPD) can be recognized with an accuracy beyond 90%. The experimental results show that the license plate recognition algorithm has high recognition accuracy, strong generalization ability, and good robustness.","Title: Research on energy saving algorithm of field animal monitoring based on cluster sensor network\nYear: 2022\n\nAbstract: Monitoring the diversity of wild animals is a core part of the research and protection of wild animals. Due to the harsh outdoor environment, researchers cannot squat in the deep forest for a long time. Therefore, designing a sensor network system for wildlife monitoring is of great value to wildlife research, protection, and management. When deploying a wildlife monitoring network in the wild environment, it is necessary to solve the problem of the effective use of energy. To this end, this paper proposes an energy-saving optimization method for node scheduling and a wake-up scheme based on a cultural genetic algorithm. This method achieves the purpose of energy saving by making redundant nodes fall asleep and waking up sleep nodes to repair the coverage blind area caused by dead nodes. Simulation results show that this method can activate fewer sensor nodes to monitor the required sensing area, and its performance is better than other known solutions.","Title: Contrast-Aware Color Consistency Correction for Multiple Images\nYear: 2022\n\nAbstract: Color consistency optimization for multiple images is a challenging task in remote sensing and computer vision. To ensure that the visual quality of corrected images is satisfactory, not only should the color discrepancies between multiple images be invisible but also the contrast of individual images should be visually appealing. Most color correction approaches focus on eliminating drastic color discrepancies, but ignore the problem of image contrast enhancement. Some color correction approaches even tend to degrade the image contrast to ensure that the image tones are consistent especially when the contrast of input images is low. To solve this problem, we present a contrast-aware color consistency correction approach in this article. We attempt to eliminate the drastic color differences and enhance the contrast of input images simultaneously. We creatively integrate the problems of color consistency correction and image contrast enhancement into the same global energy optimization framework, and we also design a special cost function to minimize the color discrepancies and enhance the image contrast using the original color information. Thus, although the contrast of input images is low, our approach can still generate the corrected images with consistent tones and visually appealing contrast. At last, we select several challenging datasets to evaluate our approach. The experimental results visually and quantitatively demonstrate the effectiveness and superiority of the proposed contrast-aware color consistency correction approach. The results also demonstrate that our approach significantly outperforms the existing approaches, especially when the contrast of the input images is low.","Title: An adaptive clonal selection algorithm with multiple differential evolution strategies\nYear: 2022\n\nAbstract: •An adaptive clonal selection algorithm with multiple differential evolution strategies is proposed.•An adaptive strategy pool with three differential evolution is employed to guide the evolution process.•A linear population size reduction method is adopted to accelerate convergence speed.•A premature convergence detection method and a stagnation detection method are proposed.•Experimental results show the effectiveness of the proposed method for numerical optimization.","Title: Optimizing Local Alignment along the Seamline for Parallax-Tolerant Orthoimage Mosaicking\nYear: 2022\n\nAbstract: Orthoimage mosaicking with obvious parallax caused by geometric misalignment is a challenging problem in the field of remote sensing. Because the obvious objects are not included in the digital terrain model (DTM), large parallax exists in these objects. A common strategy is to search an optimal seamline between orthoimages, avoiding the majority of obvious objects. However, stitching artifacts may remain because (1) the seamline may still cross several obvious objects and (2) the orthoimages may not be precisely aligned in geometry when the accuracy of the DTM is low. While applying general image warping methods to orthoimages can improve the local geometric consistency of adjacent images, these methods usually significantly modify the geometric properties of orthophoto maps. To the best of our knowledge, no approach has been proposed in the field of remote sensing to solve the problem of local geometric misalignments after orthoimage mosaicking with obvious parallax. In this paper, we creatively propose a method to optimize local alignment along the seamline after seamline detection. It consists of the following main processes. First, we locate regions with geometric misalignments along the seamline based on the similarity measure. Second, for any one region, we find one-dimensional (1D) feature matches along the seamline using a semi-global matching approach. The deformation vectors are calculated for these matches. Third, these deformation vectors are robustly and smoothly propagated into the buffer region centered on the seamline by minimizing the associated energy function. Finally, we directly warp the orthoimages to eliminate the local parallax under the guidance of dense deformation vectors. The experimental results on several groups of orthoimages show that our proposed approach is capable of eliminating the local parallax existing in the seamline while preserving most geometric properties of digital orthophoto maps, and that it outperforms state-of-the-art approaches in terms of both visual quality and quantitative metrics.","Title: DeepMLE: A Robust Deep Maximum Likelihood Estimator for Two-view Structure from Motion.\nYear: 2022\n\nAbstract: Two-view structure from motion (SfM) is the cornerstone of 3D reconstruction and visual SLAM (vSLAM). Many existing end-to-end learning-based methods usually formulate it as a brute regression problem. However, the inadequate utilization of traditional geometry model makes the model not robust in unseen environments. To improve the generalization capability and robustness of end-to-end two-view SfM network, we formulate the two-view SfM problem as a maximum likelihood estimation (MLE) and solve it with the proposed framework, denoted as DeepMLE. First, we propose to take the deep multi-scale correlation maps to depict the visual similarities of 2D image matches decided by ego-motion. In addition, in order to increase the robustness of our framework, we formulate the likelihood function of the correlations of 2D image matches as a Gaussian and Uniform mixture distribution which takes the uncertainty caused by illumination changes, image noise and moving objects into account. Meanwhile, an uncertainty prediction module is presented to predict the pixel-wise distribution parameters. Finally, we iteratively refine the depth and relative camera pose using the gradient-like information to maximize the likelihood function of the correlations. Extensive experimental results on several datasets prove that our method significantly outperforms the state-of-the-art end-to-end two-view SfM approaches in accuracy and generalization capability.","Title: A discrete clonal selection algorithm for filter-based local feature selection\nYear: 2022\n\nAbstract: Feature selection algorithms aim to improve the per-formance of machine learning algorithms by removing irrelevant and redundant features. Various feature selection algorithms have been proposed, but most of them select a global feature subset for characterizing the entire sample space. In contrast, this study proposes an efficient discrete clonal selection algorithm for local feature selection called DCSA-LFS with three features: (1) local sample behaviors are considered, and a local clustering-based evaluation criterion is used to select a distinct optimized feature subset for each different sample region; (2) an improved discrete clonal selection algorithm is proposed, which uses a differential evolution-based mutation operator to enhance the search capability of clonal selection algorithms; and (3) a two-part antibody representation is adopted to automatically adjust the weight-related parameter. Experimental results on twelve UCI datasets show that DCSA-LFS is competitive with traditional filter-based feature selection algorithms and a clonal selection algorithm-based local feature selection algorithm.","Title: An Improved Waste Detection and Classification Model Based on YOLOV5\nYear: 2022\n\nAbstract: The improvement in people's lives has resulted in a significant rise in the amount of household garbage created on a daily basis, to the point where waste separation can no longer be disregarded, especially for the series of problems: manual waste classification is time-consuming and laborious, and human waste classification errors are caused by a lack of knowledge reserve related to waste classification. To address these issues, we propose a waste classification network YOLO-CG optimized on the basis of YOLOV5 network structure in campus scene. Firstly, YOLO-CG draws lessons from the optimization idea of Transformer performance improvement by stacking the ConvNeXt Blocks in the ratio of 3:3:9:3 as backbone, adding the big size kernel and other adjustments, upgrading the mean average precision (mAP) of the network model by 5%. Then, to maintain the original accuracy while reducing the number of parameters, a computationally reduced cheap operation is introduced, which employs a simple 3 * 3 convolution to achieve a low-cost acquisition of redundant feature maps, resulting in a reduction of 12% in parameter count while also increasing the mAP. Both theoretical analysis and experiments demonstrate the effectiveness of the improved network model."],"string":"[\n \"Title: Multi-Layer Background Subtraction Based On Color And Texture\\nYear: 2007\\n\\nAbstract: In this paper, we propose a robust multi-layer background subtraction technique which takes advantages of local texture features represented by local binary patterns (LBP) and photometric invariant color measurements in RGB color space. LBP can work robustly with respective to light variation on rich texture regions but not so efficiently on uniform regions. In the latter case, color information should overcome LBPs limitation. Due to the illumination invariance of both the LBP feature and the selected color feature, the method is able to handle local illumination changes such as cast shadows from moving objects. Due to the use of a simple layer-based strategy, the approach can model moving background pixels with quasi-periodic flickering as well as background scenes which may vary over time due to the addition and removal of long-time stationary objects. Finally, the use of a cross-bilateral filter allows to implicitely smooth detection results over regions of similar intensity and preserve object boundaries. Numerical and qualitative experimental results on both simulated and real data demonstrate the robustness of the proposed method.\",\n \"Title: Automatic laser-based identification for UF6 cylinders.\\nYear: 2013\\n\\nAbstract: We present a laser item identification system (L2IS), installed in a real facility on trial, that is capable of automatically monitoring all transfers of uranium hexafluoride (UF) cylinders between different process areas. Each cylinder has a unique ‘fingerprint’ represented by the 3D micro-structure of its surface which remains intact even under extreme environmental conditions. L2IS automatically identifies each cylinder through exploring the 3D frontal surface acquired by the laser scanner. The system is composed of a portable unit (operated in attended mode) and a fixed installed unit (operated without inspector presence). The efficiency and accuracy of our identification system were evaluated on a large dataset acquired during several years including a full year of field testing.\",\n \"Title: Global Uniform Synchronization With Estimated Error Under Transmission Channel Noise\\nYear: 2009\\n\\nAbstract: This paper investigates the problem of estimating synchronization errors and its application to global uniform synchronization with an estimated error bound for the master-slave chaos synchronization scheme via linear control input, which is possibly subject to disturbances by unknown but bounded channel noise and time-delay. Based on Lyapunov function, Razumikhin technique, nonlinear parametric v...\",\n \"Title: Fast Individual Facial Animation\\nYear: 2005\\n\\nAbstract: We present a fast approach to generate individual face model and to produce relevant facial animation. Firstly, a frontal face image is captured with an ordinary video camera, and 85 key points are automatically detected. Then the points are used for RBF network to deform a generic model to an individual model. The texture is generated from the same image and texture coordinates are interpolated. Finally we transfer the original vertex motion vectors to the individual model in real time. All the procedure can be implemented with minimal or even without manual tuning. The result shows that our method is fast enough for common applications.\",\n \"Title: Systematic Static Shadow Detection\\nYear: 2004\\n\\nAbstract: A systematic static shadow detection algorithm for color images is presented in this paper. The image is modeled by an undirected graph and the shadow detection is achieved through maximizing the graph probability using the EM algorithm. Further analysis shows the connection between our model and the relaxation labeling (RL) model. Experiments clearly indicate that our method is superior to a state-of-the-art shadow detection algorithm.\",\n \"Title: Efficient importance sampling for high-sigma yield analysis with adaptive online surrogate modeling\\nYear: 2013\\n\\nAbstract: Massively repeated structures such as SRAM cells usually require extremely low failure rate. This brings on a challenging issue for Monte Carlo based statistical yield analysis, as huge amount of samples have to be drawn in order to observe one single failure. Fast Monte Carlo methods, e.g. importance sampling methods, are still quite expensive as the anticipated failure rate is very low. In this paper, a new method is proposed to tackle this issue. The key idea is to improve traditional importance sampling method with an efficient online surrogate model. The proposed method improves the performance for both stages in importance sampling, i.e. finding the distorted probability density function, and the distorted sampling. Experimental results show that the proposed method is 1e2X~1e5X faster than the standard Monte Carlo approach and achieves 5X~22X speedup over existing state-of-the-art techniques without sacrificing estimation accuracy.\",\n \"Title: Automatic medical image annotation and retrieval\\nYear: 2008\\n\\nAbstract: The demand for automatically annotating and retrieving medical images is growing faster than ever. In this paper, we present a novel medical image retrieval method for a special medical image retrieval problem where the images in the retrieval database can be annotated into one of the pre-defined labels. Even more, a user may query the database with an image that is close to but not exactly what he/she expects. The retrieval consists of the deducible retrieval and the traditional retrieval. The deducible retrieval is a special semantic retrieval and is to retrieve the label that a user expects while the traditional retrieval is to retrieve the images in the database which belong to this label and are most similar to the query image in appearance. The deducible retrieval is achieved using SEMI-supervised Semantic Error-Correcting output Codes (SEMI-SECC). The active learning method is also exploited to further reduce the number of the required ground truthed training images. Relevance feedbacks (RFs) are used in both retrieval steps: in the deducible retrieval, RF acts as a short-term memory feedback and helps identify the label that a user expects; in the traditional retrieval, RF acts as a long-term memory feedback and helps ground truth the unlabelled training images in the database. The experimental results on IMAGECLEF 2005 [] annotation data set clearly show the strength and the promise of the presented methods.\",\n \"Title: Cournot Equilibrium in Price-Capped Two-Settlement Electricity Markets\\nYear: 2005\\n\\nAbstract: We compare two alternative mechanisms for capping prices in two-settlement electricity markets. With sufficient lead time and competitive entry opportunities, forward market prices are implicitly capped by competitive pressure of potential entry that will occur when forward prices rise above a certain level. Another more direct approach is to cap spot prices through regulatory intervention. In this paper we explore the implications of the two alternative mechanisms in a two settlement Cournot equilibrium framework. We formulate the market equilibrium as a stochastic equilibrium problem with equilibrium constraints (EPEC) capturing congestion effects, probabilistic contingencies and market power. As an illustrative test case we use the 53-bus Belgian electricity network with representative generator cost but hypothetical demand and ownership assumptions. When compared to two-settlement systems without price caps we find that either of the price capping alternatives results in reduced forward contracting. Furthermore the reduction in spot prices due to forward contracting is smaller.\",\n \"Title: Hybrid group search optimiser with quadratic interpolation method and its application\\nYear: 2011\\n\\nAbstract: Group Search Optimiser (GSO) is a new swarm intelligence optimiser algorithm inspired by animal social behaviours. In this paper, we proposed two variants of GSO to improve its search capability, and applied them to solving non-linear equations. Producers in the GSO are like the eyes of animals, which determine the \\\"ï戮聵food' position and the movement direction of scroungers. However, due to the random sample mechanism, the computational efficiency is poor. To improve its search efficiency, a new GSO based on quadratic interpolation method (QIGSO) is proposed, in which the estimated position with quadratic interpolation theory is used to replace the random point in each iteration to increase the speed of convergence. Furthermore, the steepest gradient descent method is also incorporated into QIGSO (QIGSO_SDO) to improve the local search capability. Numerical simulation and a special problem about radar detection are used to test the proposed two variants.\",\n \"Title: An efficient image-based rendering method\\nYear: 2004\\n\\nAbstract: Given a set of images of the same scene, we propose an efficient method for realistically synthesizing a new image seen from a new viewpoint. Compared with some existing techniques which explicitly reconstruct the 3D geometry of the scene, we directly reconstruct the colour of each pixel in the new image by utilizing a weighted photoconsistency constraint. Global photoconsistency constraint of one pixel is firstly utilized to generate a list of plausible colours for each rendered pixel in the new image. Considering the existing of partial occlusion or the deficiencies in the image-formation model, we iteratively update the colour for each rendered pixel based on local texture statistics similar to the input images. Experimental results on the generation of a new image from a new viewing position from a set of input images show that our proposed method is promising and satisfactory.\",\n \"Title: Cournot Equilibria In Two-Settlement Electricity Markets With System Contingencies\\nYear: 2007\\n\\nAbstract: We study Nash equilibrium in two-settlement competitive electricity markets with horizontal market power, flow congestion, demand uncertainties and probabilistic system contingencies. The equilibrium is formulated as a stochastic Equilibrium Problem with Equilibrium Constraints (EPEC) in which each firm solves a stochastic Mathematical Programme with Equilibrium Constraints (MPEC). We assume a no-arbitrage relationship between the forward prices and the spot prices. We find that, with two settlements, the generation firms have incentives to commit forward contracts, which increase social surplus and decrease spot energy prices. Furthermore, these effects are amplified when the markets become less concentrated.\",\n \"Title: Image-based modeling and rendering from multiple views: a multiple cues based propagation approach\\nYear: 2005\\n\\nAbstract: In this paper we present a method for modeling a complex scene from a small set of images and then synthesizing a new view. Consider one of input images as the reference image, a small set of reliable pixel matches are initially selected and then propagated to neighboring pixels based on the clustering-based light invariant photoconsistency constraint and the data-driven depth smoothness constraint, which are integrated into a pixel matching quality function to deal with occlusions, light changes and depth discontinuity. The mismatched points in propagation are then iteratively rectified. Thus, the 3D structures of the scene are expressed by a large set of densely matched 3D points. For a new view, we initialize it by projecting these matched points. Both match propagation and mismatch rectification are used to complete the whole rendering task.\",\n \"Title: A video based personalized face model generation approach for network 3d games\\nYear: 2005\\n\\nAbstract: We have developed a fast generation system for personalized 3D face model and plan to apply it in network 3D games. This system uses one video camera to capture player’s frontal face image for 3D modeling and dose not need calibration and plentiful manual tuning. The 3D face model in games is represented by a 3D geometry mesh and a 2D texture image. The personalized geometry mesh is obtained by deforming an original mesh with the relative positions of the player’s facial features, which are automatically detected from the frontal image. The relevant texture image is also obtained from the same image. In order to save storage space and network bandwidth, only the feature data and texture data from each player are sent to the game server and then to other clients. Finally, players can see their own faces in multiplayer games.\",\n \"Title: Sparse Key Points Controlled Animation for Individual Face Model\\nYear: 2008\\n\\nAbstract: We use RBF deformation and normal projection to regulate the scanned facial model, which makes their topology equivalent to a regular grid mesh and can generate principle components. Then the synthesized individual face model can be directly flatten to a regular plan, so the motion vectors of vertexes can be interpolated with barycentric coordinate. The regulation and animation remapping needs less than 40 key points and can work in real-time\",\n \"Title: Importance Boundary Sampling for SRAM Yield Analysis With Multiple Failure Regions\\nYear: 2014\\n\\nAbstract: SRAM cells generally require an extremely low failure rate (i.e., high yield) in the per cell basis to ensure a reasonably moderate yield for the whole chip. Existing yield analysis methods still encounter issues related to multiple failure regions resulting from high-dimensional process parameter space and/or multiple performance specifications. This paper proposes a new method that combines the advantages of existing importance sampling and boundary searching methods, and avoids issues in both. The key idea is to first find all likely failure regions and then, do importance sampling on these regions. Surrogate models are used to further accelerate the method so that SPICE-simulations can be highly reduced. Experimental results show that the proposed method is suitable for handling problems with multiple failure regions. Meanwhile, it can provide $5{\\\\rm X}{\\\\sim}20{\\\\rm X}$ speed-up over other existing techniques.\",\n \"Title: A multimodal approach to time-invariant scene retrieval from single overhead image\\nYear: 2004\\n\\nAbstract: We investigate a practical problem of time-invariant scene retrieval from single airport overhead image. A multimodal approach is developed to solving for the problem, in which an efficient method using image modality data is developed for time-specific object detection, and a method using graphics modality data is developed for removal of the detected objects. Theoretical analyses and experimental evaluations show the efficiency and the effectiveness of the approach.\",\n \"Title: A unified fuzzy feature indexing scheme for region based online image querying\\nYear: 2003\\n\\nAbstract: We describe a novel indexing and retrieval methodology integrating color, texture and shape information for content-based image retrieval in online image databases. This methodology, called PicSearcher, applies unsupervised image segmentation to partition an image into a set of regions, then fuzzy color histogram as well as fuzzy texture and shape properties of each region is calculated to be part of their signatures. The fuzzification procedures resolve the recognition uncertainty stemming from color quantization and human perception of colors. At the same time, this unified fuzzy scheme incorporates the segmentation-related uncertainties into the retrieval algorithm. Then an adaptive and effective measure for the overall similarity between images is developed by integrating properties of all the regions in the image. An implemented prototype system of PicSearcher has demonstrated a promising retrieval performance for an online test database containing 10,000 general-purpose color images, as compared with its peer systems in the literature.\",\n \"Title: Object Detection in Aerial Imagery Based on Enhanced Semi-Supervised Learning\\nYear: 2005\\n\\nAbstract: Object detection in aerial imagery has been well studied in computer vision for years. However, given the complexity of large variations of the appearance of the object and the background in a typical aerial image, a robust and efficient detection is still considered as an open and challenging problem. In this paper, we present the Enhanced Semi-Supervised Learning (ESL) framework and apply this framework to revising an object detection methodology we have developed in a previous effort. Theoretic analysis and experimental evaluation using the UCI machine learning repository clearly indicate the superiority of the ESL framework. The performance evaluations of the revised object detection methodology against the original one clearly demonstrate the promise and superiority of this approach.\",\n \"Title: \\\"Automatic\\\" multimodal medical image fusion\\nYear: 2003\\n\\nAbstract: This paper addresses the multimodal medical image fusion problem. To deliver the expected fusion accuracy, most of the state-of-the-art fusion algorithms have the typical requirement - a set of fiducial points between the two modalities of the images to \\\"guide\\\" the fusion. This paper aims at removing this requirement, resulting in an \\\"automatic\\\" multimodal medical image fusion methodology based on an innovative model using Electro Static Equilibrium theory called ESE that can be used in clinical diagnoses and evaluations with accepted fusion accuracy. By \\\"automatic\\\", it is meant that the fusion algorithm per se does not require fiducial points; it does require a certain form of human interactions in terms of providing users a list of parameter settings at the beginning of the fusion, that are case-based, anatomy-based, and image-modality-based, and it does even allow users to have an option to change the specific values of the parameter settings to accommodate specific clinical needs. This \\\"automatic\\\" approach allows radiologists to save their time/effort in identifying and marking the fiducial points in the images, allows physicians and radiologists to apply their domain expertise more intelligently in \\\"playing with\\\" different parameter settings in a higher level when running this algorithm in diagnoses, and also allows patients to avoid the inconvenience to be placed under the fiducial markings. Preliminary evaluations against one of the existing fusion methods have shown that ESE holds a great promise in future medical applications.\",\n \"Title: 3D modeling and rendering from multiple wide-baseline images by match propagation\\nYear: 2006\\n\\nAbstract: In this paper, we present a method for modeling a complex scene from a small set of input images taken from widely separated viewpoints and then synthesizing novel views. First, we find sparse correspondences across multiple input images and calibrate these input images taken with unknown cameras. Then one of the input images is chosen as the reference image for modeling by match propagation. A sparse set of reliably matched pixels in the reference image is initially selected and then propagated to neighboring pixels based on both the clustering-based light invariant photoconsistency constraint and the data-driven depth smoothness constraint, which are integrated into a pixel matching quality function to efficiently deal with occlusions, light changes and depth discontinuity. Finally, a novel view rendering algorithm is developed to fast synthesize a novel view by match propagation again. Experimental results show that the proposed method can produce good scene models from a small set of widely separated images and synthesize novel views in good quality.\",\n \"Title: Analyzing Semantic Segmentation Using Hybrid Human-Machine CRFs\\nYear: 2013\\n\\nAbstract: Recent trends in semantic image segmentation have pushed for holistic scene understanding models that jointly reason about various tasks such as object detection, scene recognition, shape analysis, contextual reasoning. In this work, we are interested in understanding the roles of these different tasks in aiding semantic segmentation. Towards this goal, we \\\"plug-in\\\" human subjects for each of the various components in a state-of-the-art conditional random field model (CRF) on the MSRC dataset. Comparisons among various hybrid human-machine CRFs give us indications of how much \\\"head room\\\" there is to improve segmentation by focusing research efforts on each of the tasks. One of the interesting findings from our slew of studies was that human classification of isolated super-pixels, while being worse than current machine classifiers, provides a significant boost in performance when plugged into the CRF! Fascinated by this finding, we conducted in depth analysis of the human generated potentials. This inspired a new machine potential which significantly improves state-of-the-art performance on the MRSC dataset.\",\n \"Title: A fast individual face modeling and facial animation system\\nYear: 2006\\n\\nAbstract: In this paper, we present a fast individual face modeling and animation system. The input of the system is a single frontal face image, which is captured by an ordinary video camera. And the output is 3D individual facial animation. Firstly, an Adaboost method is used to detect the face in the image. Then the key points of the face are located with the inverse compositional algorithm based active appearance models (AAM). The 3D geometry mesh of the individual face is then generated with morphable models. Finally, the direction and magnitude of existed motion vectors are adjusted according to different 3D face shapes using expression cloning technique. With this system, we can achieve realistic 3D facial animation with minimal and often no manual tuning. The experiments show that our system is fast enough for common applications.\",\n \"Title: Fast human detection from joint appearance and foreground feature subset covariances\\nYear: 2011\\n\\nAbstract: We present a fast method to detect humans from stationary surveillance videos. It is based on a cascade of LogitBoost classifiers which use covariance matrices as object descriptors. We have made several contributions. First, our method learns the correlation between appearance and foreground features and show that the human shape information contained in foreground observations can dramatically improve performance when used jointly with appearance cues. This contrasts with traditional approaches that exploit background subtraction as an attentive filter, by applying still image detectors only on foreground regions. As a second contribution, we show that using the covariance matrices of feature subsets rather than of the full set in boosting provides similar or better performance while significantly reducing the computation load. The last contribution is a simple image rectification scheme that removes the slant of people in images when dealing with wide angle cameras, allowing for the appropriate use of integral images. Extensive experiments on a large video set show that our approach performs much better than the attentive filter paradigm while processing 5–20 frames/s. The efficiency of our subset approach with state-of-the-art results is also demonstrated on the INRIA human (static image) database.\",\n \"Title: Robust multi-view feature matching from multiple unordered views\\nYear: 2007\\n\\nAbstract: This paper explores the problem of multi-view feature matching from an unordered set of widely separated views. A set of local invariant features is extracted independently from each view. First we propose a new view-ordering algorithm that organizes all the unordered views into clusters of related (i.e. the same scene) views by efficiently computing the view-similarity values of all view pairs by reasonably selecting part of extracted features to match. Second a robust two-view matching algorithm is developed to find initial matches, then detect the outliers and finally incrementally find more reliable feature matches under the epipolar constraint between two views from dense to sparse based on an assumption that changes of both motion and feature characteristics of one match are consistent with those of neighbors. Third we establish the reliable multi-view matches across related views by reconstructing missing matches in a neighboring triple of views and efficiently determining the states of matches between view pairs. Finally, the reliable multi-view matches thus obtained are used to automatically track all the views by using a self-calibration method. The proposed methods were tested on several sets of real images. Experimental results show that it is efficient and can track a large set of multi-view feature matches across multiple widely separated views.\",\n \"Title: Two-settlement electricity markets with price caps and Cournot generation firms\\nYear: 2007\\n\\nAbstract: We compare two alternative mechanisms for capping prices in two-settlement electricity markets. With sufficient lead time, forward market prices are implicitly capped by competitive pressure of potential entry that will occur when forward prices rise above some backstop price. Another more direct approach is to cap spot prices through a regulatory intervention. In this paper we explore the implications of these two alternative mechanisms in a two-settlement Cournot equilibrium framework. We formulate the market equilibrium as a stochastic equilibrium problem with equilibrium constraints (EPEC) capturing congestion effects, probabilistic contingencies and horizontal market power. As an illustrative test case, we use the 53-bus Belgian electricity network with representative generator costs but hypothetical demand and ownership structure. Compared to a price-uncapped two-settlement system, a forward cap increases firms’ incentives for forward contracting, whereas a spot cap reduces such incentives. Moreover, in both cases, more forward contracts are committed as the generation resource ownership structure becomes more diversified.\",\n \"Title: Efficient model-based linear head motion recovery from movies\\nYear: 2004\\n\\nAbstract: In this paper, we propose an efficient method that estimates the motion parameters of a human head from a video sequence by using a three-layer linear iterative process. In the innermost layer, we estimate the motion of each input face image in a video sequence based on a generic face model and a small set of feature points. A fast iterative least-square method is used to recover these motion parameters. After that, we iteratively estimate three model scaling factors using multiple frames with the recovered poses in the middle layer. Finally, we update 3D coordinates of the feature points on the generic face model in the outermost layer. Since all iterative processes can be solved linearly, the computational cost is low. Tests on synthetic data under noisy conditions and two real video sequences have been performed. Experimental results show that the proposed method is robust and has good performance.\",\n \"Title: Robust range image registration using 3D lines\\nYear: 2010\\n\\nAbstract: We present an efficient method for accurate automatic registration of two geometrically complex 3D range scans by using 3D lines. We first detect edges from the associated 2D reflectance images and collect 3D edge contours by only taking into account valid foreground points. Then we use an efficient split-and-merge line fitting algorithm to detect 3D lines. We build a fast search codebook to efficiently match the two sets of 3D lines. This is done by computing the orientation angle and distance of pairs of 3D lines in each set, both of which are invariant under rigid transformations. Finally we recover the rigid transformation between two scans using an efficient RANSAC algorithm with robust transformation estimation that exploits two sets of corresponding 3D lines. We conclude presenting experimental results that demonstrate efficiency and accuracy of our proposed method.\",\n \"Title: Semi-supervised learning based object detection in aerial imagery\\nYear: 2005\\n\\nAbstract: Object detection in aerial imagery has been well studied in computer vision for years. However, given the complexity of large variations of the appearance of the object and the background in a typical aerial image, a robust and efficient detection is still considered as an open and challenging problem. In this paper, we have developed a theoretic foundation for aerial imagery object detection using semi-supervised learning algorithms. Based on this theory, we have proposed a context-based object detection methodology. Both theoretic analyses and experimental evaluations have successfully demonstrated the great promise of the developed theory and the related detection methodology.\",\n \"Title: 3D modeling from multiple images\\nYear: 2010\\n\\nAbstract: Although the visual perception of 3D shape from 2D images is a basic capability of human beings, it remains challenging to computers Hence, one goal of vision research is to computationally understand and model the latent 3D scene from the captured images, and provide human-like visual system for machines In this paper, we present a method that is capable of building a realistic 3D model for the latent scene from multiple images taken at different viewpoints Specifically, the reconstruction proceeds in two steps First, generate dense depth map for each input image by a Bayesian-based inference model Second, build a complete 3D model for the latent scene by integrating all reliable 3D information embedded in the depth maps Experiments are conducted to demonstrate the effectiveness of the proposed approach.\",\n \"Title: Complex and photo-realistic scene representation based on range planar segmentation and model fusion\\nYear: 2011\\n\\nAbstract: We present an efficient 3D scene representation method from a set of 3D range scans captured from a large-scale indoor or outdoor scene based on range planar segmentation and model fusion. In our method, range images are partitioned into planar patches and non-planar regions. We first partition the range image into a set of rectangle blocks and fit a planar patch to all points of each block. Blocks that are not successfully fitted as planar patches, are iteratively partitioned into sub-blocks until reaching a minimum size. Second, we iteratively merge the planar patches and identify unclassified rectangle blocks or points. The segmentation is then refined by relabelling the boundary points of fitted planar patches with respect to the neighbouring planar patches. We further simplify the scene model representation by fusing range scans and welding neighbouring planar patches with clean straight boundaries. An efficient texture mapping approach is proposed to automatically map the reflectance/colour images onto the fused scene model composed of a set of planar patches. Finally we successfully demonstrate the performance of our algorithms on several challenging range data sets.\",\n \"Title: Automatic Medical Image Annotation and Retrieval Using SECC\\nYear: 2006\\n\\nAbstract: The demand for automatically annotating and retrieving medical images is growing faster than ever. In this paper, we present a novel medical image annotation method based on the proposed Semantic Error-Correcting output Codes (SECC). With this annotation method, we present a new semantic image retrieval method, which exploits the high level semantic similarity. For example, a user may query the system using an image of arm while he/she expects images of hand. This cannot be realized by traditional retrieval methods. The experimental results on the IMAGECLEF 2005 annotation data set clearly show the strength and the promise of the presented methods.\",\n \"Title: Hierarchical shadow detection for color aerial images\\nYear: 2006\\n\\nAbstract: A hierarchical shadow detection algorithm for color aerial images is presented in this paper to meet two challenges for static shadow detection in the literature: different brightness and illumination conditions in different images and the complexity of aerial images. The hierarchical algorithm consists of two levels of processing: the pixel level classification, achieved through modelling an image as a reliable graph (RG) and maximizing the graph reliability using the EM algorithm, and the region level verification, achieved through minimizing the Bayesian error by further exploiting the domain knowledge. Further analyses show that MRF model based segmentation is a special case of the RG model. The relationship between the RG model and the relaxation labeling model is also discussed. A quantitative comparison between this method and a state-of-the-art shadow detection algorithm clearly indicates that this method is promising for delivering effective shadow detection performance under different illumination and brightness conditions.\",\n \"Title: Robust surface registration using N-points approximate congruentsets\\nYear: 2011\\n\\nAbstract: Scans acquired by 3D sensors are typically represented in a local coordinate system. When multiple scans, taken from different locations, represent the same scene these must be registered to a common reference frame. We propose a fast and robust registration approach to automatically align two scans by finding two sets of N-points, that are approximately congruent under rigid transformation and leading to a good estimate of the transformation between their corresponding point clouds. Given two scans, our algorithm randomly searches for the best sets of congruent groups of points using a RANSAC-based approach. To successfully and reliably align two scans when there is only a small overlap, we improve the basic RANSAC random selection step by employing a weight function that approximates the probability of each pair of points in one scan to match one pair in the other. The search time to find pairs of congruent sets of N-points is greatly reduced by employing a fast search codebook based on both binary and multi-dimensional lookup tables. Moreover, we introduce a novel indicator of the overlapping region quality which is used to verify the estimated rigid transformation and to improve the alignment robustness. Our framework is general enough to incorporate and efficiently combine different point descriptors derived from geometric and texture-based feature points or scene geometrical characteristics. We also present a method to improve the matching effectiveness of texture feature descriptors by extracting them from an atlas of rectified images recovered from the scan reflectance image. Our algorithm is robust with respect to different sampling densities and also resilient to noise and outliers. We demonstrate its robustness and efficiency on several challenging scan datasets with varying degree of noise, outliers, extent of overlap, acquired from indoor and outdoor scenarios.\",\n \"Title: Automatic Medical Image Annotation And Retrieval Using Semi-Secc\\nYear: 2006\\n\\nAbstract: The demand for automatically annotating and retrieving medical images is growing faster than ever. In this paper, we present a novel medical image retrieval method based on SEMI-supervised Semantic Error-Correcting output Codes (SEMI-SECC). The experimental results on IMAGECLEF 2005 [1] annotation data set clearly show the strength and the promise of the presented methods.\",\n \"Title: Clustering-based match propagation for image-based rendering from multiple images\\nYear: 2004\\n\\nAbstract: In this paper we propose a novel method for rendering a new view from multiple input images. A set of reliable pixel matches are initially selected and then propagated to neighboring pixels based on the piecewise smooth assumption in the spatial domain and the clustering-based photoconsistency constraint which is applied to handle pixel occlusion, partial pixel effects and lighting effects between images. Experimental results show that the proposed algorithm is promising and satisfactory.\",\n \"Title: Automatic marker detection from X-ray images\\nYear: 2013\\n\\nAbstract: In this paper, we present a novel automatic marker detection method for X-ray images in the framework of machine learning, which is different from those approaches using traditional template matching or fitting algorithms based on prior knowledge. First we propose to use the covariance-based descriptors to effectively represent the marker features in X-ray images. Then we utilize the cascade of LogitBoost classifiers based on covariance features to learn the marker detector, which automatically locates the markers on a X-ray image with a high detection rate and a low false alarm rate. Finally a large amount of experimental results demonstrate that our proposed approach is quite suitable and effective for the marker detection in X-ray images.\",\n \"Title: Modeling and Computing Two-Settlement Oligopolistic Equilibrium in a Congested Electricity Network\\nYear: 2008\\n\\nAbstract: A model of two-settlement electricity markets is introduced, which accounts for flow congestion, demand uncertainty, system contingencies, and market power. We formulate the subgame perfect Nash equilibrium for this model as an equilibrium problem with equilibrium constraints (EPEC), in which each firm solves a mathematical program with equilibrium constraints (MPEC). The model assumes linear demand functions, quadratic generation cost functions, and a lossless DC network, resulting in equilibrium constraints as a parametric linear complementarity problem (LCP). We introduce an iterative procedure for solving this EPEC through repeated application of an MPEC algorithm. This MPEC algorithm is based on solving quadratic programming subproblems and on parametric LCP pivoting. Numerical examples demonstrate the effectiveness of the MPEC and EPEC algorithms and the tractability of the model for realistic-size power systems.\",\n \"Title: Fusing color and texture features for stereo matching\\nYear: 2013\\n\\nAbstract: This paper presents a novel method for stereo matching by fusing color and texture features. Instead of using color features only, which is very similar to most of stereo matching algorithms proposed in recent years, we propose to integrate color features and texture ones in the matching cost function. In this way, more reliable matches can be found in the stereo matching. Firstly we introduce a new texture descriptor, namely, the multi-layer Local Ternary Patterns (LTP), in the matching cost function. Different from the original LTP, our multi-layer descriptor can represent the pixel as specific as possible. Secondly a recently proposed filtering method called the adaptive manifolds filtering is adopted as the cost aggregation strategy. This filtering is a high-dimensional real-time filter operator, which has been verified to be very effective in many image processing fields while is firstly utilized in stereo matching. Finally experiments conducted in the Middlebury benchmark sufficiently verify the effectiveness of our proposed stereo matching algorithm.\",\n \"Title: Pedestrian detection from still images based on multi-feature covariances\\nYear: 2013\\n\\nAbstract: This paper targets the detection of pedestrians from still images, which focuses on developing robust feature representations that encode image regions as covariance matrices to support high accuracy pedestrian/non-pedestrian decisions. Firstly we utilize a fast method for computation of covariances based on integral images. By integrating the advantages of both covariance-based object detection and HOG-and FDF-based pedestrian detection, we then introduce four new feature representations for training a pedestrian detector: Covariance-based first-order Histogram of Oriented Gradient (Cov-HOG1), Covariance-based second-order Histogram of Oriented Gradient (Cov-HOG2), Covariance-based first-order Four Directional Features (Cov-FDF1), and Covariance-based second-order Four Directional Features (Cov-FDF2). To test our feature sets, we adopt a relatively simple learning framework that uses LogitBoost algorithm to classify each possible image region as a pedestrian or as a non-pedestrian. The experimental results show that the proposed algorithm obtains satisfactory pedestrian detection performances on the INRIA person datasets as well as images collected from Google and Flickr websites.\",\n \"Title: Scalable Compact Modeling for On-Chip Passive Elements with Correlated Parameter Extraction and Adaptive Boundary Compression\\nYear: 2014\\n\\nAbstract: Scalable compact models for passive elements are important in the Analog/RF circuit design and optimization. Traditional scalable modeling methods are mainly physical and manual based methods, which usually require deep physical insight and extensive human intervention. In this paper, an automatic scalable compact modeling method for generic passive elements is established. The proposed method is a unified parameter extraction and scalable modeling scheme with novel inner-loop correlated parameter extraction and outer-loop adaptive boundary compression techniques. Experimental results show that both accuracy and scalability have been achieved by the proposed method for industrial inductors and transformers with an acceptable computational cost.\",\n \"Title: Scale selection based on Moran's I for segmentation of high resolution remotely sensed images\\nYear: 2014\\n\\nAbstract: Image segmentation is a prerequisite for object-based image analysis (OBIA). However, selecting an optimal segmentation scale is often time consuming and needs trial-and-error. This paper presents an unsupervised scale selection method based on the rate of change of a spatial autocorrelation indicator - the global Moran's I for segmentation of high resolution remotely sensed images. It was compared with other two scale selection methods and its effectiveness is validated through both visual analysis and by referencing to multiple manual segmentations. Experimental results on our own data and statistical data from an external reference showed that the optimal scale could be easily selected through the proposed method.\",\n \"Title: Robust Line Matching Based On Ray-Point-Ray Structure Descriptor\\nYear: 2014\\n\\nAbstract: In this paper, we propose a novel two-view line matching method through converting matching line segments extracted from two uncalibrated images to matching the introduced Ray-Point-Ray (RPR) structures. The method first recovers the partial connectivity of line segments through sufficiently exploiting the gradient map. To efficiently matching line segments, we introduce the Ray-Point-Ray (RPR) structure consisting of a joint point and two rays (line segments) connected to the point. Two sets of RPRs are constructed from the connected line segments extracted from two images. These RPRs are then described with the proposed SIFT-like descriptor for efficient initial matching to recover the fundamental matrix. Based on initial RPR matches and the recovered fundamental matrix, we propose a match propagation scheme consisting of two stages to refine and find more RPR matches. The first stage is to propagate matches among those initially formed RPRs, while the second stage is to propagate matches among newly formed RPRs constructed by intersecting unmatched line segments with those matched ones. In both stages, candidate matches are evaluated by comprehensively considering their descriptors, the epipolar line constraint, and the topological consistency with neighbor point matches. Experimental results demonstrate the good performance of the proposed method as well as its superiority to the state-of-the-art methods.\",\n \"Title: Estimating Drivable Collision-Free Space from Monocular Video\\nYear: 2015\\n\\nAbstract: In this paper we propose a novel algorithm for estimating the drivable collision-free space for autonomous navigation of on-road and on-water vehicles. In contrast to previous approaches that use stereo cameras or LIDAR, we show a method to solve this problem using a single camera. Inspired by the success of many vision algorithms that employ dynamic programming for efficient inference, we reduce the free space estimation task to an inference problem on a 1D graph, where each node represents a column in the image and its label denotes a position that separates the free space from the obstacles. Our algorithm exploits several image and geometric features based on edges, color, and homography to define potential functions on the 1D graph, whose parameters are learned through structured SVM. We show promising results on the challenging KITTI dataset as well as video collected from boats.\",\n \"Title: An efficient time step control method in transient simulation for DAE system\\nYear: 2014\\n\\nAbstract: Adaptive time step control is very important or even crucial in transient simulation for the efficiency of a circuit simulator. Existing methods are mainly based on the formula of the local truncation error (LTE) for solving ordinary differential equations (ODEs), which is an approximation for the circuit simulator solving a system of nonlinear differential algebraic equations (DAEs). In this work, we derived the formula of LTE for DAE system and proposed a new time step control method. Experimental results show that the proposed method works well for industrial circuits.\",\n \"Title: An Efficient SRAM Yield Analysis and Optimization Method With Adaptive Online Surrogate Modeling\\nYear: 2015\\n\\nAbstract: SRAM cells usually require extremely low failure rate or equivalently extremely high production yield, making it impractical to perform yield analysis using Monte Carlo (MC) method as huge amount of samples are needed. Fast MC methods, e.g., importance sampling methods, are still too expensive as the anticipated failure rate is very low. In this paper, a new SRAM yield analysis method is proposed to tackle this issue. The key idea is to improve traditional importance sampling method with an efficient online surrogate model. Experimental results show that the proposed yield analysis method achieves – speedup over existing state-of-the-art techniques without sacrificing estimation accuracy. Sigma distribution and schmoo plot can be quickly generated by the proposed method, which is very useful for realistic applications. Based on the proposed yield analysis method, an efficient yield optimization method has been developed to further automate the SRAM cell design procedure where process variations can be fully considered. Experimental results show that a fully automatic yield optimization for SRAM cells can be done within only a few hours.\",\n \"Title: Alterations of the human gut microbiome in liver cirrhosis.\\nYear: 2014\\n\\nAbstract: Liver cirrhosis occurs as a consequence of many chronic liver diseases that are prevalent worldwide. Here we characterize the gut microbiome in liver cirrhosis by comparing 98 patients and 83 healthy control individuals. We build a reference gene set for the cohort containing 2.69 million genes, 36.1% of which are novel. Quantitative metagenomics reveals 75,245 genes that differ in abundance between the patients and healthy individuals (false discovery rate < 0.0001) and can be grouped into 66 clusters representing cognate bacterial species; 28 are enriched in patients and 38 in control individuals. Most (54%) of the patient-enriched, taxonomically assigned species are of buccal origin, suggesting an invasion of the gut from the mouth in liver cirrhosis. Biomarkers specific to liver cirrhosis at gene and function levels are revealed by a comparison with those for type 2 diabetes and inflammatory bowel disease. On the basis of only 15 biomarkers, a highly accurate patient discrimination index is created and validated on an independent cohort. Thus microbiota-targeted biomarkers may be a powerful tool for diagnosis of different diseases.\",\n \"Title: Hierarchical line matching based on Line-Junction-Line structure descriptor and local homography estimation.\\nYear: 2016\\n\\nAbstract: This paper presents a hierarchical method for matching line segments from two images. Line segments are matched first in groups and then in individuals. While matched in groups, the line segments lying adjacently are intersected to form junctions. At the places of the junctions, the structures are constructed called Line–Junction–Line (LJL), which consists of two adjacent line segments and their intersecting junction. To reliably deal with the possible scale change between the two images to be matched, we propose to describe LJLs by a robust descriptor in the multi-scale pyramids of images constructed from two original images. By evaluating the description vector distances of LJLs from the two images, some candidate LJL matches are obtained, which are then refined and expanded by an effective match-propagation strategy. The line segments used to construct LJLs are matched when the LJLs they formed are matched. For those left unmatched line segments, we match them in individuals by utilizing the local homographies estimated from their neighboring matched LJLs. Experiments demonstrate the superiorities of the proposed method to the state-of-the-art methods for its robustness in more difficult situations, the larger amounts of correct matches, and the higher accuracy in most cases.\",\n \"Title: Accurate Text Localization in Natural Image with Cascaded Convolutional Text Network.\\nYear: 2016\\n\\nAbstract: We introduce a new top-down pipeline for scene text detection. We propose a novel Cascaded Convolutional Text Network (CCTN) that joints two customized convolutional networks for coarse-to-fine text localization. The CCTN fast detects text regions roughly from a low-resolution image, and then accurately localizes text lines from each enlarged region. We cast previous character based detection into direct text region estimation, avoiding multiple bottom- up post-processing steps. It exhibits surprising robustness and discriminative power by considering whole text region as detection object which provides strong semantic information. We customize convolutional network by develop- ing rectangle convolutions and multiple in-network fusions. This enables it to handle multi-shape and multi-scale text efficiently. Furthermore, the CCTN is computationally efficient by sharing convolutional computations, and high-level property allows it to be invariant to various languages and multiple orientations. It achieves 0.84 and 0.86 F-measures on the ICDAR 2011 and ICDAR 2013, delivering substantial improvements over state-of-the-art results [23, 1].\",\n \"Title: Adaptive Human Behavior Modeling for Air Combat Simulation.\\nYear: 2015\\n\\nAbstract: Military simulations, especially those for personnel training and equipment effectiveness analysis, require proper human behavior models (HBMs) to play blue or red. Traditionally, the HBMs are controlled through rule based scripts. However, the doctrine-driven behavior is rigid and predictable, and more often than not unable to adapt to new situations. In most cases, the subject matter experts (SMEs) review, re-design a large amount of HBM scripts for new scenarios or training tasks, which is challenging and time-consuming. Therefore, a study of using Grammatical Evolution (GE) to generate adaptive HBMs for air combat simulation is conducted in this work. Expert knowledge is encoded with modular behavior trees (BTs) for the compatibility with the operators in genetic algorithm (GA). GE maps HBMs represented with BTs to binary strings, and uses GA to evolve HBMs with the performance fed back from simulation. Beyond visual range air combat experiments between adaptive HBMs and none-adaptive baseline HBMs are conducted to study the evolutionary process. The experimental results show that the GE is an efficient framework to generate adaptive HBMs in BTs formalism and evolve them with GA.\",\n \"Title: MULTI-CAMERA 3D PERSON TRACKING WITH PARTICLE FILTER IN A SURVEILLANCE ENVIRONMENT\\nYear: 2008\\n\\nAbstract: In this work we present and evaluate a novel 3D approach to track single people in surveillance scenarios, using multiple cameras. The problem is formulated in a Bayesian filtering framework, and solved through sampling approximations (i.e. using a particle fil- ter). Rather than relying on a 2D state to represent people, as is most commonly done, we directly exploit 3D knowledge by track- ing people in the 3D world. A novel dynamical model is presented that accurately models the coupling between people orientation and motion direction. In addition, people are represented by three 3D elliptic cylinders which allow to introduce a spatial color layout useful to discriminate the tracked person from potential distractors. Thanks to the particle filter approach, integrating background sub- traction and color observations from multiple cameras is straight- forward. Alltogether, the approach is quite robust to occlusion and large variations in people appearence, even when using a single camera, as demonstrated by numerical performance evaluation on real and challenging data from an underground station.\",\n \"Title: Model-architecture oriented combat system effectiveness simulation.\\nYear: 2015\\n\\nAbstract: Combat system effectiveness simulation (CESS) is a special type of complex system simulation. Three non-functional requirements (NFRs), i.e. model composability, domain-specific modeling, and model evolvability are gaining higher priority from CESS users when evaluating different modeling methodologies for CESS. Traditional CESS modeling methodologies are either domain-neutral (lack of domain characteristics consideration and limited support for model composability) or domain-oriented (lack of openness and evolvability) and fall short of the three NFRs. Inspired by the concept of architecture in systems engineering and software engineering fields, we extend it into a concept of model architecture for complex simulation systems, and propose a model-architecture oriented modeling methodology in which model architecture plays a central role in achieving the three NFRs. Various model-driven engineering (MDE) approaches and technologies, including SMP, UML, DSM, and so forth, are applied where possible in representing the CESS model architecture and its components' behaviors from physical and cognitive domain aspects.\",\n \"Title: Magnetic-Gravity Gradient Inversion For Underwater Object Detection\\nYear: 2015\\n\\nAbstract: A new underwater object detection method based on joint Gravity-Gradient and Magnetic-Gradient Inversion algorithms is proposed in this paper. Magnetic gradient and gravity gradient anomalies induced by an underwater object can be measured and inversed to estimate the relative changes in distance between underwater object and underwater vehicle. The weight least squares estimation is introduced to combine equations of magnetic gradient and gravity gradient inversion. Therefore, the joint inversion method gets an optimal relative position of underwater object using two kinds of data. Simulation results show that the proposed method is more efficient than the previous Joint gravity - gradient tensor inversion and magnetic gradient tensor inversion respectively.\",\n \"Title: Strong Authentication Scheme Based On Hand Geometry And Smart Card Factors\\nYear: 2016\\n\\nAbstract: In 2009, Xu et al. presented a safe, dynamic, id-based on remote user authentication method that has several advantages such as freely chosen passwords and mutual authentication. In this paper, we review the Xu-Zhu-Feng scheme and indicate many shortcomings in their scheme. Impersonation attacks and insider attacks could be effective. To overcome these drawbacks, we propose a secure biometric-based remote authentication scheme using biometric characteristics of hand-geometry, which is aimed at withstanding well-known attacks and achieving good performance. Furthermore, our work contains many crucial merits such as mutual authentication, user anonymity, freely chosen passwords, secure password changes, session key agreements, revocation by using personal biometrics, and does not need extra device or software for hand geometry in the login phase. Additionally, our scheme is highly efficient and withstands existing known attacks like password guessing, server impersonation, insider attacks, denial of service (DOS) attacks, replay attacks, and parallel-session attacks. Compared with the other related schemes, our work is powerful both in communications and computation costs.\",\n \"Title: Line Segment Matching: A Benchmark\\nYear: 2016\\n\\nAbstract: As the vital procedure for exploiting line segments extracted from images for solving computer vision problems, Line Segment Matching (LSM) has received growing attentions from researcher in recent years, and a considerable number of methods have been proposed. However, no one has attempted to solve two major problems in this area. The first is how to evaluate different methods in an unbiased way. All proposed methods were evaluated using images and line segment detectors selected by the authors themselves, making the conclusions based on the somewhat biased experiments less convincing. The second problem is that there is no reliably automatic way to access the correctness of obtained line segment matches, which can often be up to hundreds in quantity. Checking them one by one by visual inspection is the only reliable, but very tedious and error-prone way. In this paper, we target to solve the two problems. We introduce a benchmark which provides the ground truth matches among 30 pairs of line segment sets extracted from 15 representative image pairs using two state-of-the-art line segment detectors. With the benchmark, we evaluated some of the existing LSM methods.\",\n \"Title: Joint Point And Line Segment Matching On Wide-Baseline Stereo Images\\nYear: 2016\\n\\nAbstract: This paper presents an method that matches points and line segments jointly on wide-baseline stereo images. In both two images to be matched, line segments are extracted and those spatially adjacent ones are intersected to generate V-junctions. To match V-junctions from the two images, we extract for each of them an affine and scale invariant local region and describe it with SIFT. The putative V-junction matches obtained from evaluating their description vectors are refined subsequently by the epipolar line constraint and topological distribution constraint among neighbor V-junctions. Since once a pair of V-junctions are matched, the two pairs of line segments forming them are matched accordingly. A part of line segments from the two images are therefore matched along with V-junction matches. To get more line segment matches, we further match those left unmatched line segments by the local homographies estimated from their adjacent V-junction matches. Experiments verify the robustness of the proposed method and its superiority to both some famous point and line segment matching methods on wide-baseline stereo images. In addition, we also show the proposed method can make it easier for 3D line segment reconstruction.\",\n \"Title: Motion-free exposure fusion based on inter-consistency and intra-consistency.\\nYear: 2017\\n\\nAbstract: Exposure fusion often suffers from ghost artifacts, which are caused by the movement of objects when a dynamic scene is captured. In this paper, two types of consistency concepts are introduced for enforcing the guidance of a reference image for motion detection and ghost removal. Specifically, the inter-consistency, which represents the similarities of pixel intensities among different exposures, is weakened by the use of different exposure settings. Histogram matching is employed to recover the inter-consistency. Following this, pixel differences are mostly the result of changes in content caused by object movements, so motion can easily be detected. To further restrain the weights of outliers in fusion, motion detection is performed at a super-pixel level, to ensure that pixels with similar intensities and structures share similar fusion weights. This is referred to as intra-consistency. Experiments in various dynamic scenes demonstrate that the proposed algorithm can determine the motion more effectively than existing methods, and produce high quality fusion results that are free of ghost artifacts.\",\n \"Title: A Unified Framework for Street-View Panorama Stitching.\\nYear: 2017\\n\\nAbstract: In this paper, we propose a unified framework to generate a pleasant and high-quality street-view panorama by stitching multiple panoramic images captured from the cameras mounted on the mobile platform. Our proposed framework is comprised of four major steps: image warping, color correction, optimal seam line detection and image blending. Since the input images are captured without a precisely common projection center from the scenes with the depth differences with respect to the cameras to different extents, such images cannot be precisely aligned in geometry. Therefore, an efficient image warping method based on the dense optical flow field is proposed to greatly suppress the influence of large geometric misalignment at first. Then, to lessen the influence of photometric inconsistencies caused by the illumination variations and different exposure settings, we propose an efficient color correction algorithm via matching extreme points of histograms to greatly decrease color differences between warped images. After that, the optimal seam lines between adjacent input images are detected via the graph cut energy minimization framework. At last, the Laplacian pyramid blending algorithm is applied to further eliminate the stitching artifacts along the optimal seam lines. Experimental results on a large set of challenging street-view panoramic images captured form the real world illustrate that the proposed system is capable of creating high-quality panoramas.\",\n \"Title: Learning to Refine Object Contours with a Top-Down Fully Convolutional Encoder-Decoder Network.\\nYear: 2017\\n\\nAbstract: We develop a novel deep contour detection algorithm with a top-down fully convolutional encoder-decoder network. Our proposed method, named TD-CEDN, solves two important issues in this low-level vision problem: (1) learning multi-scale and multi-level features; and (2) applying an effective top-down refined approach in the networks. TD-CEDN performs the pixel-wise prediction by means of leveraging features at all layers of the net. Unlike skip connections and previous encoder-decoder methods, we first learn a coarse feature map after the encoder stage in a feedforward pass, and then refine this feature map in a top-down strategy during the decoder stage utilizing features at successively lower layers. Therefore, the deconvolutional process is conducted stepwise, which is guided by Deeply-Supervision Net providing the integrated direct supervision. The above proposed technologies lead to a more precise and clearer prediction. Our proposed algorithm achieved the state-of-the-art on the BSDS500 dataset (ODS F-score of 0.788), the PASCAL VOC2012 dataset (ODS F-score of 0.588), and and the NYU Depth dataset (ODS F-score of 0.735).\",\n \"Title: Globally consistent alignment for planar mosaicking via topology analysis.\\nYear: 2017\\n\\nAbstract: In this paper, we propose a generic framework for globally consistent alignment of images captured from approximately planar scenes via topology analysis, capable of resisting the perspective distortion meanwhile preserving the local alignment accuracy. Firstly, to estimate the topological relations of images efficiently, we search for a main chain connecting all images over a fast built similarity table of image pairs (mainly for the unordered image sequence), along which the potential overlapping pairs are incrementally detected according to the gradually recovered geometric positions and orientations. Secondly, all the sequential images are organized as a spanning tree through applying a graph algorithm on the topological graph, so as to find the optimal reference image which minimizes the total number of error propagation. Thirdly, the global alignment under topology analysis is performed in the strategy that images are initially aligned by groups via the affine model, followed by the homography refinement under the anti-perspective constraint, which manages to keep the optimal balance between aligning precision and global consistency. Finally, experimental results on two challenging aerial image sets illustrate the superiority of the proposed approach. HighlightsA generic framework for mosaicking (ordered and unordered) images captured from an approximately planar scene is proposed.Method finding a valid main chain of unordered images efficiently by the Minimum Spanning Tree (MST) algorithm is proposed.A global alignment strategy able to keep an optimal balance between global consistency and aligning accuracy is proposed.\",\n \"Title: 2-Line Exhaustive Searching for Real-Time Vanishing Point Estimation in Manhattan World\\nYear: 2017\\n\\nAbstract: This paper presents a very simple and efficient algorithm to estimate 1, 2 or 3 orthogonal vanishing point(s) on a calibrated image in Manhattan world. Unlike the traditional methods which apply 1, 3, 4, or 6 line(s) to generate vanishing point hypotheses, we propose to use 2 lines to get the first vanishing point v1, then uniformly take sample of the second vanishing point v2 on the great circle of v1 on the equivalent sphere, and finally calculate the third vanishing point v3 by the cross-product of v1 and v2. There are three advantages of the proposed method over traditional multi-line method. First, the 2-line model is much more robust and reliable than the multi-line method, which can be applied in the scene with 1, 2 or 3 orthogonal vanishing point(s). Second, the probability of the 2-line model being formed of inner line segments can be calculated given the outlier ratio, which means that the number of iterations can be determined, and thus the estimation of vanishing points can be performed in a very simple exhaustive way instead of the traditional RANSAC method. Third, the real-time performance is achieved by building a polar grid for the line intersection points, which functions as a lookup table for the validation of vanishing point hypotheses. Our algorithm has been validated successfully in the YUD dataset and sets of challenging real images.\",\n \"Title: Optimal Seamline Detection for Orthoimage Mosaicking by Combining Deep Convolutional Neural Network and Graph Cuts.\\nYear: 2017\\n\\nAbstract: When mosaicking orthoimages, especially in urban areas with various obvious ground objects like buildings, roads, cars or trees, the detection of optimal seamlines is one of the key technologies for creating seamless and pleasant image mosaics. In this paper, we propose a new approach to detect optimal seamlines for orthoimage mosaicking with the use of deep convolutional neural network (CNN) and graph cuts. Deep CNNs have been widely used in many fields of computer vision and photogrammetry in recent years, and graph cuts is one of the most widely used energy optimization frameworks. We first propose a deep CNN for land cover semantic segmentation in overlap regions between two adjacent images. Then, the energy cost of each pixel in the overlap regions is defined based on the classification probabilities of belonging to each of the specified classes. To find the optimal seamlines globally, we fuse the CNN-classified energy costs of all pixels into the graph cuts energy minimization framework. The main advantage of our proposed method is that the pixel similarity energy costs between two images are defined using the classification results of the CNN based semantic segmentation instead of using the image informations of color, gradient or texture as traditional methods do. Another advantage of our proposed method is that the semantic informations are fully used to guide the process of optimal seamline detection, which is more reasonable than only using the hand designed features defined to represent the image differences. Finally, the experimental results on several groups of challenging orthoimages show that the proposed method is capable of finding high-quality seamlines among urban and non-urban orthoimages, and outperforms the state-of-the-art algorithms and the commercial software based on the visual comparison, statistical evaluation and quantitative evaluation based on the structural similarity (SSIM) index.\",\n \"Title: Optimal seamline detection in dynamic scenes via graph cuts for image mosaicking.\\nYear: 2017\\n\\nAbstract: In this paper, we present a novel method for creating a seamless mosaic from a set of geometrically aligned images captured from the scene with dynamic objects at different times. The artifacts caused by dynamic objects and geometric misalignments can be effectively concealed in our proposed seamline detection algorithm. In addition, we simultaneously compensate the image regions of dynamic objects based on the optimal seamline detection in the graph cuts energy minimization framework and create the mosaic with a relatively clean background. To ensure the high quality of the optimal seamline, the energy functions adopted in graph cuts combine the pixel-level similarities of image characteristics, including intensity and gradient, and the texture complexity. To successfully compensate the image regions covered by dynamic objects for creating a mosaic with a relatively clean background, we initially detect them in overlap regions between images based on pixel-level and region-level similarities, then refine them based on segments, and determine their image source in probability based on contour matching. We finally integrate all of these into the energy minimization framework to detect optimal seamlines. Experimental results on different dynamic scenes demonstrate that our proposed method is capable of generating high-quality mosaics with relatively clean backgrounds based on the detected optimal seamlines.\",\n \"Title: Low-Cost High-Accuracy Variation Characterization For Nanoscale Ic Technologies Via Novel Learning-Based Techniques\\nYear: 2018\\n\\nAbstract: Faster and more accurate variation characterizations of semiconductor devices/circuits are in great demand as process technologies scale down to Fin-FET era. Traditional methods with intensive data testing are extremely costly. In this paper, we propose a novel learning-based high-accuracy data prediction framework inspired by learning methods from computer vision to efficiently characterize variabilities of device/circuit behaviors induced by manufacturing process variations. The key idea is to adaptively learn the underlying data pattern among data with variations from a small set of already obtained data and utilize it to accurately predict the unmeasured data with minimum physical measurement cost. To realize this idea, novel regression modeling techniques based on Gaussian process regression and partial least squares regression with feature extraction and matching are developed. We applied our approach to real-time variation characterization for transistors with multiple geometries from a foundry 28nm CMOS process. The results show that the framework achieves about 14x time speed-up with on average 0.1 A error for variation data prediction and under 0.3% error for statistical extraction compared to traditional physical measurements, which demonstrates the efficacy of the framework for accurate and fast variation analysis and statistical modeling.\",\n \"Title: Fine-grained Video Attractiveness Prediction Using Multimodal Deep Learning on a Large Real-world Dataset.\\nYear: 2018\\n\\nAbstract: Nowadays, billions of videos are online ready to be viewed and shared. Among an enormous volume of videos, some popular ones are widely viewed by online users while the majority attract little attention. Furthermore, within each video, different segments may attract significantly different numbers of views. This phenomenon leads to a challenging yet important problem, namely fine-grained video attractiveness prediction, which only relies on video contents to forecast video attractiveness at fine-grained levels, specifically video segments of several second length in this paper. However, one major obstacle for such a challenging problem is that no suitable benchmark dataset currently exists. To this end, we construct the first fine-grained video attractiveness dataset (FVAD), which is collected from one of the most popular video websites in the world. In total, the constructed FVAD consists of 1,019 drama episodes with 780.6 hours covering different categories and a wide variety of video contents. Apart from the large amount of videos, hundreds of millions of user behaviors during watching videos are also included, such as view counts, \\\"fast-forward, \\\"fast-rewind, and so on, where \\\"view counts\\\" reflects the video attractiveness while other engagements capture the interactions between the viewers and videos. First, we demonstrate that video attractiveness and different engagements present different relationships. Second, FVAD provides us an opportunity to study the fine-grained video attractiveness prediction problem. We design different sequential models to perform video attractiveness prediction by relying solely on video contents. The sequential models exploit the multimodal relationships between visual and audio components of the video contents at different levels. Experimental results demonstrate the effectiveness of our proposed sequential models with different visual and audio representations, the necessity of incorporating the two modalities, and the complementary behaviors of the sequential prediction models at different levels.\",\n \"Title: Edge-Enhanced Optimal Seamline Detection for Orthoimage Mosaicking.\\nYear: 2018\\n\\nAbstract: In this letter, we propose a novel algorithm to detect the optimal seamline by using the edge-enhanced energy function for orthoimage mosaicking. First, we generate the energy cost map by using traditional intensity and gradient difference. Then, to ensure that the detected optimal seamlines avoid crossing the obvious objects, the energy map is enhanced in the regions of valid edge segments around...\",\n \"Title: Tactics Exploration Framework Based On Genetic Programming\\nYear: 2017\\n\\nAbstract: Engagement-level simulation is a quantitative way to evaluate the effectiveness of weapon systems before construction and acquisition, minimizing the risk of investment. Though contractors have built simulation systems with high fidelity models of weapon systems and battlefields, developing competent tactics to give full play to new weapon systems in simulation experiments is labor intensive, as most classical tactics tend to be out of date. In this work, we proposed a tactics exploration framework (TEF) that applied grammar-based genetic programming (GP) to generating and evolving tactics in the engagement-level simulation. Tactics are represented with modular behavior trees (BTs) for compatibility with the genetic operators. Experiments to explore submarine tactics have been conducted to observe and study the exploration process. The experimental results show that the TEF based on GP is efficient to explore tactics in the formalism of BTs.\",\n \"Title: Relaxed two points projection method for solving the multiple-sets split equality problem.\\nYear: 2018\\n\\nAbstract: The multiple-sets split equality problem, a generalization and extension of the split feasibility problem, has a variety of specific applications in real world, such as medical care, image reconstruction, and signal processing. It can be a model for many inverse problems where constraints are imposed on the solutions in the domains of two linear operators as well as in the operators’ ranges simultaneously. Although, for the split equality problem, there exist many algorithms, there are but few algorithms for the multiple-sets split equality problem. Hence, in this paper, we present a relaxed two points projection method to solve the problem; under some suitable conditions, we show the weak convergence and give a remark for the strong convergence method in the Hilbert space. The interest of our algorithm is that we transfer the problem to an optimization problem, then, based on the model, we present a modified gradient projection algorithm by selecting two different initial points in different sets for the problem (we call the algorithm as two points algorithm). During the process of iteration, we employ subgradient projections, not use the orthogonal projection, which makes the method implementable. Numerical experiments manifest the algorithm is efficient.\",\n \"Title: Generalized Content-Preserving Warps for Image Stitching.\\nYear: 2018\\n\\nAbstract: Local misalignment caused by global homography is a common issue in image stitching task. Content-Preserving Warping (CPW) is a typical method to deal with this issue, in which geometric and photometric constraints are imposed to guide the warping process. One of its essential condition however, is colour consistency, and an elusive goal in real world applications. In this paper, we propose a Generalized Content-Preserving Warping (GCPW) method to alleviate this problem. GCPW extends the original CPW by applying a colour model that expresses the colour transformation between images locally, thus meeting the photometric constraint requirements for effective image stitching. We combine the photometric and geometric constraints and jointly estimate the colour transformation and the warped mesh vertexes, simultaneously. We align images locally with an optimal grid mesh generated by our GCPW method. Experiments on both synthetic and real images demonstrate that our new method is robust to colour variations, outperforming other state-of-the-art CPW-based image stitching methods.\",\n \"Title: Subtracted Histogram: Utilizing Mutual Relation Between Features for Thresholding.\\nYear: 2018\\n\\nAbstract: In this paper, we propose a thresholding method utilizing the mutual relation between the two used features, which should be both robust and of low correlation. The mutual relation is exploited through a histogram subtraction transformation, which tries to reduce only the background part of each of the histograms for the features so that we can easily differentiate between the background part and ...\",\n \"Title: Single Image Haze Removal via Joint Estimation of Detail and Transmission\\nYear: 2018\\n\\nAbstract: Single image haze removal is an important task in computer vision. However, haze removal is an extremely challenging problem due to it is massively ill-posed, which is that we need to estimate the transmission and the corresponding haze-free pixel from a single color measurement at each pixel. In this paper, we propose a new deep learning based method for removing haze from single input image. First, we estimate a transmission map via joint estimation of clear image details and transmission map, which is different from traditional methods which only estimating a transmission map for a hazy image. Second, we use a global regularization method to eliminate the halos and artifacts. Experimental results demonstrate that our method outperforms the other state-of-the-art dehazing methods.\",\n \"Title: Video Stitching With Extended-Meshflow\\nYear: 2018\\n\\nAbstract: In this paper, we present a method that stitches multiple videos captured with a fixed camera rig. We propose an Extended-MeshFlow motion model for video stitching. Firstly, uniform features are detected and matched at the overlapping region, from which the Exended-MeshFlow model is estimated. The model then warps the adjacent views to the common central view to eliminate the spatial misalignment. The motions located on the feature positions are interpolated to the mesh vertexes by Multilevel B-Spline Approximation(MBA). Collecting the motions on the vertexes form the vertex profiles, which are smoothed for temporal consistency. During the smoothing, only previous frames are required, thus the proposed method can stitch videos in an online mode. Experimental results on various of videos demonstrate that the proposed method can produce comparable stitching results in aspects of spatial alignment and temporal coherence.\",\n \"Title: Generalized Content-Preserving Warp: Direct Photometric Alignment Beyond Color Consistency.\\nYear: 2018\\n\\nAbstract: Motion estimation is vital in many computer vision applications. Most existing methods require high quality and large quantity of feature correspondence and may fail for images with few textures. In this paper, a photometric alignment method is proposed to obtain better motion estimation result. Since the adopted photometric constraints are usually limited to the required illumination or color consistency assumption, a new generalized content-preserving warp (GCPW) framework, therefore, is designed to perform photometric alignment beyond color consistency. Similar to conventional content-preserving warp (CPW), GCPW is also a mesh-based framework, but it extends CPW by appending a local color transformation model for every mesh quad, which expresses the color transformation from a source image to a target image within the quad. Motion-related mesh vertexes and color-related mapping parameters are optimized jointly in GCPW to get more robust motion estimation results. Evaluation of tens of videos reveals that the proposed method achieves more accurate motion estimation results. More importantly, it is robust to significant color variation. Besides, this paper explores the performance of GCPW in two popular computer vision applications: image stitching and video stabilization. Experimental results demonstrate GCPW's effectiveness in dealing with typical challenging scenes for these two applications.\",\n \"Title: Robust Camera Pose Estimation Via Consensus On Ray Bundle And Vector Field\\nYear: 2018\\n\\nAbstract: Estimating the camera pose requires point correspondences. However, in practice, correspondences are inevitably corrupted by outliers, which affects the pose estimation. We propose a general and accurate outlier removal strategy for robust camera pose estimation. The proposed strategy can detect outliers by leveraging the fact that only inliers comply with two effective consensuses, i.e., 3D ray bundle consensus and 2D vector field consensus. Our strategy has a nested structure. First, the outer module utilizes the 3D ray bundle consensus. We define the likelihood based on the probabilistic mixture model and maximize it by the expectation-maximization (EM) algorithm. The inlier probability of each correspondence and the camera pose are determined alternately. Second, the inner module exploits the 2D vector field consensus to refine the probabilities obtained by the outer module. The refinement based on the Bayesian rule facilitates the convergence of the outer module and improves the accuracy of the entire framework. Our strategy can be integrated into various existing camera pose estimation methods which are originally vulnerable to outliers. Experiments on both synthesized data and real images have shown that our approach outperforms state-of-the-art outlier rejection methods in terms of accuracy and robustness.\",\n \"Title: Evaluation Model of the Artist Based on Fuzzy Membership to Improve the Principal Component Analysis of Robust Kernel\\nYear: 2016\\n\\nAbstract: Principal component analysis is a number of related indexes into a multivariate statistical method a fewrelated indicators, often used in data compression and feature extraction are widely used in industry, agriculture, economy, biology, medicine, astronomy, geography and other fields. In the classical principal component analysis, each training data in construction the main ingredient is the same. However, in many practical problems, the significance and effect of the training data is different, usually some of the data than other data is moreimportant. We should pay more attention to the important data, should play a greater role in the construction of the main components, and the data may be not credible is the abnormal data, should limit its role. In this paper, each training data gives a confidence weight to the training data as fuzzy points in the sample space, based on the research Principal component analysis and kernel principal component analysis of fuzzy point data. In this paper, an analysis method based on the principal component analysis of the objective weight is presented, and the method is applied to the evaluation of the value of the artist's creation. The paper analyses the in kernel principal component analysis KPCA, input data space X reflect the shoot diameter: R P, h is projected onto a new high-dimensional feature space h after, although you can achieve nonlinear feature extraction, but still in the presence of outliers. In feature space, we can reduce the effect of outliers, and avoid the effect of the traditionalprinciple component analysis, so it has the advantages of robust and nonlinear. In fact, we show that the fuzzy membership degree of fuzzy membership degree is improved, and the accuracy rate is 84%.We use the kernel principal component analysis method to improve the original foundation, and realize the construction of the artist evaluation model, and improve the accuracy.\",\n \"Title: Superpixel-Based Optimal Seamline Detection Via Graph Cuts For Panoramic Images\\nYear: 2016\\n\\nAbstract: In this paper, we present a novel method for seamlessly mosaicking panoramic images based on superpixels in the graph cuts energy minimization framework. To effectively ensure that all seamlines are detected in the laterally continuous regions with the high image similarity and the low object dislocation, the energy functions adopted in graph cuts combine the pixel-level similarities of image characteristics, including intensity and gradient, and the texture complexity. Instead of finding the optimal solution of seamlines in overlap regions via graph cuts among the entire set of pixels, we find it among superpixels created from input images, which greatly improves the efficiency of the global graph cuts energy optimization because the number of elements in graph cuts dramatically decreases. Experimental results demonstrate that the superpixel-based method is capable of generating high-quality seamlines as the pixel-based method but greatly reduces the computation time.\",\n \"Title: 3d Line Segment Reconstruction In Structured Scenes Via Coplanar Line Segment Clustering\\nYear: 2016\\n\\nAbstract: This paper presents a new algorithm aiming for 3D Line Segment (LS) reconstruction in structured scenes that are comprised of a set of planes. Due to location imprecision of image LSs, it often produces many erroneous reconstructions when reconstructing 3D LSs by triangulating corresponding LSs from two images. We propose to solve this problem by first recovering space planes and then back-projecting image LSs onto the recovered space planes to get reliable 3D LSs. Given LS matches identified from two images, we estimate a set of planar homographies and use them to cluster the LS matches into groups such that LS matches in each group are related by the same homography induced by a space plane. In each LS match group, the corresponding space plane can be recovered from the 3D LSs obtained by triangulating all the LS correspondences. To reduce the incidence of incorrect LS match grouping, we formulate to solve the LS match grouping problem into solving a multi-label optimization problem. The advantages of the proposed algorithm over others in this area are that it can generate more complete and detailed 3D models of scenes using much fewer images and can recover the space planes where the reconstructed 3D LSs lie, which is beneficial for upper level applications, like scene understanding and building facade extraction.\",\n \"Title: Multi-Oriented and Scale-Invariant License Plate Detection Based on Convolutional Neural Networks.\\nYear: 2019\\n\\nAbstract: License plate detection (LPD) is the first and key step in license plate recognition. State-of-the-art object-detection algorithms based on deep learning provide a promising form of LPD. However, there still exist two main challenges. First, existing methods often enclose objects with horizontal rectangles. However, horizontal rectangles are not always suitable since license plates in images are multi-oriented, reflected by rotation and perspective distortion. Second, the scale of license plates often varies, leading to the difficulty of multi-scale detection. To address the aforementioned problems, we propose a novel method of multi-oriented and scale-invariant license plate detection (MOSI-LPD) based on convolutional neural networks. Our MOSI-LPD tightly encloses the multi-oriented license plates with bounding parallelograms, regardless of the license plate scales. To obtain bounding parallelograms, we first parameterize the edge points of license plates by relative positions. Next, we design mapping functions between oriented regions and horizontal proposals. Then, we enforce the symmetry constraints in the loss function and train the model with a multi-task loss. Finally, we map region proposals to three edge points of a nearby license plate, and infer the fourth point to form bounding parallelograms. To achieve scale invariance, we first design anchor boxes based on inherent shapes of license plates. Next, we search different layers to generate region proposals with multiple scales. Finally, we up-sample the last layer and combine proposal features extracted from different layers to recognize true license plates. Experimental results have demonstrated that the proposed method outperforms existing approaches in terms of detecting license plates with different orientations and multiple scales.\",\n \"Title: Single Image Dehazing Using Deep Convolution Neural Networks.\\nYear: 2017\\n\\nAbstract: Haze removal is urgently desired in multi-media system. A deep learning-based method, called dehazingCNN, is proposed to estimate an approximate clear image. The proposed learning model is different from traditional learning based method. We adopts Deep Convolution Neural Networks (CNN) to take a hazy image as the input and outputs the corresponding clear image directly. The output of the network is high quality except some block artifacts and color distortions. We can remove the color distortion in the approximate clear image via atmospheric scattering model and guided filter effectively. Experimental results on different type of images, such as synthetic and benchmark of hazy images, demonstrate that the proposed method is comparative to and even better than many complex state-of-the-art methods.\",\n \"Title: Multiple Combined Constraints For Image Stitching\\nYear: 2018\\n\\nAbstract: Several approaches to image stitching use different constraints to estimate the motion model between image pairs. These constraints can be roughly divided into two categories: geometric constraints and photometric constraints. In this paper, geometric and photometric constraints are combined to improve the alignment quality, which is based on the observation that these two kinds of constraints are complementary. On the one hand, geometric constraints (e.g., point and line correspondences) are usually spatially biased and are insufficient in some extreme scenes, while photometric constraints are always evenly and densely distributed. On the other hand, photometric constraints are sensitive to displacements and are not suitable for images with large parallaxes, while geometric constraints are usually imposed by feature matching and are more robust to handle parallaxes. The proposed method therefore combines them together in an efficient mesh-based image warping framework. It achieves better alignment quality than methods only with geometric constraints, and can handle larger parallax than photometric-constraint-based method. Experimental results on various images illustrate that the proposed method outperforms representative state-of-the-art image stitching methods reported in the literature.\",\n \"Title: Feed-Net: Fully End-to-End Dehazing.\\nYear: 2018\\n\\nAbstract: This paper proposes an image dehazing model built with a fully convolutional neural network (CNN), called Fully End-to-End Dehazing Network (FEED-Net). In contrast to estimate the transmission map and the atmospheric light separately as most previous deep learning methods, FEED-Net recovers the hazy-free image directly from a hazy image via a light-weight CNN. In addition, we introduce contextual information into dehazing via dilated convolution and use dense skip connection for feature fusion, which makes end-to-end dehazing possible. Experimental results show our method outperforms the state-of-the-art algorithms on both synthetic dataset and real-world images.\",\n \"Title: RoadNet: Learning to Comprehensively Analyze Road Networks in Complex Urban Scenes from High-Resolution Remotely Sensed Images\\nYear: 2019\\n\\nAbstract: It is a classical task to automatically extract road networks from very high-resolution (VHR) images in remote sensing. This paper presents a novel method for extracting road networks from VHR remotely sensed images in complex urban scenes. Inspired by image segmentation, edge detection, and object skeleton extraction, we develop a multitask convolutional neural network (CNN), called RoadNet, to simultaneously predict road surfaces, edges, and centerlines, which is the first work in such field. The RoadNet solves seven important issues in this vision problem: 1) automatically learning multiscale and multilevel features [gained by the deeply supervised nets (DSN) providing integrated direct supervision] to cope with the roads in various scenes and scales; 2) holistically training the mentioned tasks in a cascaded end-to-end CNN model; 3) correlating the predictions of road surfaces, edges, and centerlines in a network model to improve the multitask prediction; 4) designing elaborate architecture and loss function, by which the well-trained model produces approximately single-pixel width road edges/centerlines without nonmaximum suppression postprocessing; 5) cropping and bilinear blending to deal with the large VHR images with finite-computing resources; 6) introducing rough and simple user interaction to obtain desired predictions in the challenging regions; and 7) establishing a benchmark data set which consists of a series of VHR remote sensing images with pixelwise annotation. Different from the previous works, we pay more attention to the challenging situations, in which there are lots of shadows and occlusions along the road regions. Experimental results on two benchmark data sets show the superiority of our proposed approaches.\",\n \"Title: DeepCrack: A deep hierarchical feature learning architecture for crack segmentation.\\nYear: 2019\\n\\nAbstract: Automatic crack detection from images of various scenes is a useful and challenging task in practice. In this paper, we propose a deep hierarchical convolutional neural network (CNN), called as DeepCrack, to predict pixel-wise crack segmentation in an end-to-end method. DeepCrack consists of the extended Fully Convolutional Networks (FCN) and the Deeply-Supervised Nets (DSN). During the training, the elaborately designed model learns and aggregates multi-scale and multi-level features from the low convolutional layers to the high-level convolutional layers, which is different from the standard approaches of only using the last convolutional layer. DSN provides integrated direct supervision for features of each convolutional stage. We apply both guided filtering and Conditional Random Fields (CRFs) methods to refine the final prediction results. A benchmark dataset consisting of 537 images with manual annotation maps are built to verify the effectiveness of our proposed method. Our method achieved state-of-the-art performances on the proposed dataset (mean I/U of 85.9, best F-score of 86.5, and 0.1 s per image).\",\n \"Title: Joint learning of image detail and transmission map for single image dehazing\\nYear: 2020\\n\\nAbstract: Single image haze removal is an important task in computer vision. However, haze removal is an extremely challenging problem due to its massively ill-posed, which is that at each pixel we must estimate the transmission and the global atmospheric light from a single color measurement. In this paper, we propose a new deep learning-based method for removing haze from single input image. First, we estimate a transmission map via joint estimation of clear image detail and transmission map, which is different from traditional methods only estimating a transmission map for a hazy image. Second, we use a global regularization method to eliminate the halos and artifacts. Experimental results on synthetic dataset and real-world images show our method outperforms the other state-of-the-art methods.\",\n \"Title: Cooperative Data Sharing for Mobile Cloudlets under Heterogeneous Environments\\nYear: 2019\\n\\nAbstract: As accessing remote cloud via cellular network is costly due to the lower bandwidth, higher wide area network (WAN) latency, and higher energy consumption, mobile cloudlet that formed by several edge mobile devices has become an emerging computing paradigm and attracted increasing attention recently. Being different from the existing studies that mainly focus on the issue of computation offloading...\",\n \"Title: SeeIME: a Chinese mobile IME for Chinese learners based on hybrid Pinyin code\\nYear: 2019\\n\\nAbstract: For foreign Chinese learners, learning Pinyin is much easier than Chinese characters. Traditional Chinese input methods (IMEs) that are intended for Chinese people are not suitable for Chinese learners whose mother language is non-Chinese. In general, different languages can be translated into each other. By this feature and the relevant knowledge of existing IMEs, we take Chinese and English as an example to propose a hybrid encoding that combines Pinyin and the first two letters of its translation. We implement SeeIME with this hybrid Pinyin code. SeeIME can effectively reduce the number of candidate words and help users recognize Chinese characters better via a three-block display method. Using this code for sentence generation can improve the hit rate, which increases from 58% to 84%. The implemented IME is already available for the Android system.\",\n \"Title: The Realization Of Load Balancing Algorithm In Cloud Computing\\nYear: 2018\\n\\nAbstract: Due(1) to the large number, the length and the processing time of cloud tasks, the cloud task scheduling is unbalanced and it has the problem that the cloud computing service response will be delayed and inefficient in the cloud computing environment. This paper mainly studies the bee colony load balancing algorithm(BCLB) and establishes the mathematical model of the bee colony load balancing algorithm. The mathematical model of the Bee colony balancing algorithm is established and applied in cloud computing. It designs the algorithm implementation process and cloud task scheduling scheme. Finally, through the simulation in the CloudSim, the application of bee colony load balancing algorithm is realized in cloud computing, the experiments show that the BCLB algorithm has greater advantages than random algorithms and greedy load balancing algorithm.\",\n \"Title: The Research And Implementation Of Middleware In Cloud Computing\\nYear: 2018\\n\\nAbstract: In order to ensure(1) the security and reliability of cloud computing services, this paper uses the advantages of middleware in processing heterogeneous systems to establish a cloud middleware model. It realizes the organic combination of software platform and infrastructure platform and proposes a load balancing mechanism based on middleware. It determines the weights of various parameters based on the middleware load conditions and proposes a load balancing algorithm in middleware. It achieves more granular load balancing and ensures the security of cloud services. Finally, a cloud computer distributed system simulation platform is established. The experimental simulation shows that the middleware load balancing mechanism has good performance in cloud load balancing.\",\n \"Title: VIC-Net: Voxelization Information Compensation Network for Point Cloud 3D Object Detection\\nYear: 2021\\n\\nAbstract: Voxel-based methods have been widely used in point cloud 3D object detection. These methods usually transform points into voxels while suffering from information loss during point cloud voxelization. To address this problem, we propose a novel one-stage Voxelization Information Compensation Network (VIC-Net), which has the ability of loss-free feature extraction. The whole framework consists of a point branch for geometry detail extraction and a voxel branch for efficient proposals generation. Firstly, PointNet++ is adopted to efficiently encode geometry structure features from the raw point clouds. Then based on the encoded point features, two Point2Voxel (P2V) feature fusion modules are proposed to fuse point features with a voxel backbone, including Local P2V and Multi-Scale P2V. The P2V modules respectively integrate local detail features and multi-scale semantic contexts into a sparse voxel backbone. Thirdly, an auxiliary reconstruction loss is employed on the point branch to explicitly guide the point backbone to be aware of real geometry structures. In addition, we extend VIC-Net to a two-stage approach, namely VIC-RCNN, which further utilizes the fine geometry features to refine object locations. Experiments on the KITTI dataset demonstrate that our proposed VIC-Net outperforms other one-stage methods and our two-stage method VIC-RCNN achieves new state-of-the-art performance.\",\n \"Title: Multi-scale retinex-based adaptive gray-scale transformation method for underwater image enhancement\\nYear: 2022\\n\\nAbstract: Underwater images play an irreplaceable role as one of the carriers of underwater information acquisition. Underwater degraded images are usually affected by the color cast, noise, and blurred details, which are difficult to apply to various vision tasks. We propose a multi-scale retinex adaptive grayscale transformation underwater image enhancement method, which includes three parts: color correction, image denoising, and detail enhancement. Firstly, the multi-scale Retinex algorithm is adopted to extract the lighting components. Mean and mean square errors were introduced through linear quantization, and color recovery factors were adopted to adjust the three channels for color correction. Second, by treating the image as an anisotropic thermal field diffusing in all direction,image noise is eliminated and edge details are preserved. Finally, for different underwater degraded images, a simulated annealing optimization algorithm is introduced to perform adaptive gray-scale transformation on the image to enhance image details. The results show that the proposed method can comprehensively solve the problems of color distortion, noise, and low contrast. Compared with the state-of-the-art underwater image enhancement and restoration methods, our method has achieved better visual effects.\",\n \"Title: JPV-Net: Joint Point-Voxel Representations for Accurate 3D Object Detection.\\nYear: 2022\\n\\nAbstract: Voxel and point representations are widely applied in recent 3D object detection tasks from LiDAR point clouds. Voxel representations contribute to efficiently and rapidly locating objects, whereas point representations are capable of describing intra-object spatial relationship for detection refinement. In this work, we aim to exploit the strengths of both two representations, and present a novel two-stage detector, named Joint Point-Voxel Network (JPV-Net). Specifically, our framework is equipped with a Dual Encoders-Fusion Decoder, which consists of the dual encoders to extract voxel features of sketchy 3D scenes and point features rich in geometric context, respectively, and the Feature Propagation Fusion (FP-Fusion) decoder to attentively fuse them from coarse to fine. By making use of the advantages of these features, the refinement network can effectively eliminate false detection and provide better accuracy. Besides, to further develop the perception characteristics of voxel CNN and point backbone, we design two novel intersection-over-union (IoU) estimation modules for proposal generation and refinement, both of which can alleviate the misalignment between the localization and the classification confidence. Extensive experiments on the KITTI dataset and ONCE dataset demonstrate that our proposed JPV-Net outperforms other state-of-the-art methods with remarkable margins.\",\n \"Title: Practical Issues and Challenges in CSI-based Integrated Sensing and Communication\\nYear: 2022\\n\\nAbstract: Next-generation mobile communication network (i.e., 6G) has been envisioned to go beyond classical communication functionality and provide integrated sensing and communication (ISAC) capability to enable more emerging applications, such as smart cities, connected vehicles, AIoT and health care/elder care. Among all the ISAC proposals, the most practical and promising approach is to empower existing wireless network (e.g., WiFi, 4G/5G) with the augmented ability to sense the surrounding human and environment, and evolve wireless communication networks into intelligent communication and sensing network (e.g., 6G). In this paper, based on our experience on CSI-based wireless sensing with WiFi/4G/5G signals, we intend to identify ten major practical and theoretical problems that hinder real deployment of ISAC applications, and provide possible solutions to those critical challenges. Hopefully, this work will inspire further research to evolve existing WiFi/4G/5G networks into next-generation intelligent wireless network (i.e., 6G).\",\n \"Title: Global Color Consistency Correction for Large-Scale Images in 3-D Reconstruction\\nYear: 2022\\n\\nAbstract: Global color consistency correction for multiview images in three-dimensional (3-D) reconstruction is an important problem. The color differences between the images will affect the result of dense matching, thereby reducing the geometric accuracy of the mesh model. Moreover, it will also affect the result of texture mapping, causing color differences in the textured model. The color correction method based on global optimization is mainly used to solve this problem. And existing methods usually use sparse matching points as the color correspondences, but the correction results are not accurate enough as a result of the sparsity of the points. Besides, their efficiency of solving large-scale images globally is low. This article proposes a novel color correction method to eliminate the color differences between large-scale multiview images effectively. The core idea of our method is to group images by graph partition algorithm, and then perform intragroup correction and intergroup correction in sequence. First, for each pair of images, we calculate the reliable matching regions around the sparse points as the color correspondences according to the local homography principle. Compared with sparse matching points, our strategy can achieve more accurate color correction results. Next, for large-scale images, we partition them into many groups. For each group of images, the correction parameters are solved to eliminate the color differences of the images included in the group. Finally, we eliminate the color differences between groups by intergroup correction to achieve overall color consistency. Experimental results on typical datasets demonstrate that the proposed method is better than the current representative methods. The proposed method shows better color consistency in the extreme cases, and also exhibits higher computational efficiency on large-scale image sets.\",\n \"Title: Research and Implementation of Fast-LPRNet Algorithm for License Plate Recognition\\nYear: 2021\\n\\nAbstract: The license plate recognition is an important part of the intelligent traffic management system, and the application of deep learning to the license plate recognition system can effectively improve the speed and accuracy of recognition. Aiming at the problems of traditional license plate recognition algorithms such as the low accuracy, slow speed, and the recognition rate being easily affected by the environment, a Convolutional Neural Network- (CNN-) based license plate recognition algorithm-Fast-LPRNet is proposed. This algorithm uses the nonsegment recognition method, removes the fully connected layer, and reduces the number of parameters. The algorithm-which has strong generalization ability, scalability, and robustness-performs license plate recognition on the FPGA hardware. Increaseing the depth of network on the basis of the Fast-LPRNet structure, the dataset of Chinese City Parking Dataset (CCPD) can be recognized with an accuracy beyond 90%. The experimental results show that the license plate recognition algorithm has high recognition accuracy, strong generalization ability, and good robustness.\",\n \"Title: Research on energy saving algorithm of field animal monitoring based on cluster sensor network\\nYear: 2022\\n\\nAbstract: Monitoring the diversity of wild animals is a core part of the research and protection of wild animals. Due to the harsh outdoor environment, researchers cannot squat in the deep forest for a long time. Therefore, designing a sensor network system for wildlife monitoring is of great value to wildlife research, protection, and management. When deploying a wildlife monitoring network in the wild environment, it is necessary to solve the problem of the effective use of energy. To this end, this paper proposes an energy-saving optimization method for node scheduling and a wake-up scheme based on a cultural genetic algorithm. This method achieves the purpose of energy saving by making redundant nodes fall asleep and waking up sleep nodes to repair the coverage blind area caused by dead nodes. Simulation results show that this method can activate fewer sensor nodes to monitor the required sensing area, and its performance is better than other known solutions.\",\n \"Title: Contrast-Aware Color Consistency Correction for Multiple Images\\nYear: 2022\\n\\nAbstract: Color consistency optimization for multiple images is a challenging task in remote sensing and computer vision. To ensure that the visual quality of corrected images is satisfactory, not only should the color discrepancies between multiple images be invisible but also the contrast of individual images should be visually appealing. Most color correction approaches focus on eliminating drastic color discrepancies, but ignore the problem of image contrast enhancement. Some color correction approaches even tend to degrade the image contrast to ensure that the image tones are consistent especially when the contrast of input images is low. To solve this problem, we present a contrast-aware color consistency correction approach in this article. We attempt to eliminate the drastic color differences and enhance the contrast of input images simultaneously. We creatively integrate the problems of color consistency correction and image contrast enhancement into the same global energy optimization framework, and we also design a special cost function to minimize the color discrepancies and enhance the image contrast using the original color information. Thus, although the contrast of input images is low, our approach can still generate the corrected images with consistent tones and visually appealing contrast. At last, we select several challenging datasets to evaluate our approach. The experimental results visually and quantitatively demonstrate the effectiveness and superiority of the proposed contrast-aware color consistency correction approach. The results also demonstrate that our approach significantly outperforms the existing approaches, especially when the contrast of the input images is low.\",\n \"Title: An adaptive clonal selection algorithm with multiple differential evolution strategies\\nYear: 2022\\n\\nAbstract: •An adaptive clonal selection algorithm with multiple differential evolution strategies is proposed.•An adaptive strategy pool with three differential evolution is employed to guide the evolution process.•A linear population size reduction method is adopted to accelerate convergence speed.•A premature convergence detection method and a stagnation detection method are proposed.•Experimental results show the effectiveness of the proposed method for numerical optimization.\",\n \"Title: Optimizing Local Alignment along the Seamline for Parallax-Tolerant Orthoimage Mosaicking\\nYear: 2022\\n\\nAbstract: Orthoimage mosaicking with obvious parallax caused by geometric misalignment is a challenging problem in the field of remote sensing. Because the obvious objects are not included in the digital terrain model (DTM), large parallax exists in these objects. A common strategy is to search an optimal seamline between orthoimages, avoiding the majority of obvious objects. However, stitching artifacts may remain because (1) the seamline may still cross several obvious objects and (2) the orthoimages may not be precisely aligned in geometry when the accuracy of the DTM is low. While applying general image warping methods to orthoimages can improve the local geometric consistency of adjacent images, these methods usually significantly modify the geometric properties of orthophoto maps. To the best of our knowledge, no approach has been proposed in the field of remote sensing to solve the problem of local geometric misalignments after orthoimage mosaicking with obvious parallax. In this paper, we creatively propose a method to optimize local alignment along the seamline after seamline detection. It consists of the following main processes. First, we locate regions with geometric misalignments along the seamline based on the similarity measure. Second, for any one region, we find one-dimensional (1D) feature matches along the seamline using a semi-global matching approach. The deformation vectors are calculated for these matches. Third, these deformation vectors are robustly and smoothly propagated into the buffer region centered on the seamline by minimizing the associated energy function. Finally, we directly warp the orthoimages to eliminate the local parallax under the guidance of dense deformation vectors. The experimental results on several groups of orthoimages show that our proposed approach is capable of eliminating the local parallax existing in the seamline while preserving most geometric properties of digital orthophoto maps, and that it outperforms state-of-the-art approaches in terms of both visual quality and quantitative metrics.\",\n \"Title: DeepMLE: A Robust Deep Maximum Likelihood Estimator for Two-view Structure from Motion.\\nYear: 2022\\n\\nAbstract: Two-view structure from motion (SfM) is the cornerstone of 3D reconstruction and visual SLAM (vSLAM). Many existing end-to-end learning-based methods usually formulate it as a brute regression problem. However, the inadequate utilization of traditional geometry model makes the model not robust in unseen environments. To improve the generalization capability and robustness of end-to-end two-view SfM network, we formulate the two-view SfM problem as a maximum likelihood estimation (MLE) and solve it with the proposed framework, denoted as DeepMLE. First, we propose to take the deep multi-scale correlation maps to depict the visual similarities of 2D image matches decided by ego-motion. In addition, in order to increase the robustness of our framework, we formulate the likelihood function of the correlations of 2D image matches as a Gaussian and Uniform mixture distribution which takes the uncertainty caused by illumination changes, image noise and moving objects into account. Meanwhile, an uncertainty prediction module is presented to predict the pixel-wise distribution parameters. Finally, we iteratively refine the depth and relative camera pose using the gradient-like information to maximize the likelihood function of the correlations. Extensive experimental results on several datasets prove that our method significantly outperforms the state-of-the-art end-to-end two-view SfM approaches in accuracy and generalization capability.\",\n \"Title: A discrete clonal selection algorithm for filter-based local feature selection\\nYear: 2022\\n\\nAbstract: Feature selection algorithms aim to improve the per-formance of machine learning algorithms by removing irrelevant and redundant features. Various feature selection algorithms have been proposed, but most of them select a global feature subset for characterizing the entire sample space. In contrast, this study proposes an efficient discrete clonal selection algorithm for local feature selection called DCSA-LFS with three features: (1) local sample behaviors are considered, and a local clustering-based evaluation criterion is used to select a distinct optimized feature subset for each different sample region; (2) an improved discrete clonal selection algorithm is proposed, which uses a differential evolution-based mutation operator to enhance the search capability of clonal selection algorithms; and (3) a two-part antibody representation is adopted to automatically adjust the weight-related parameter. Experimental results on twelve UCI datasets show that DCSA-LFS is competitive with traditional filter-based feature selection algorithms and a clonal selection algorithm-based local feature selection algorithm.\",\n \"Title: An Improved Waste Detection and Classification Model Based on YOLOV5\\nYear: 2022\\n\\nAbstract: The improvement in people's lives has resulted in a significant rise in the amount of household garbage created on a daily basis, to the point where waste separation can no longer be disregarded, especially for the series of problems: manual waste classification is time-consuming and laborious, and human waste classification errors are caused by a lack of knowledge reserve related to waste classification. To address these issues, we propose a waste classification network YOLO-CG optimized on the basis of YOLOV5 network structure in campus scene. Firstly, YOLO-CG draws lessons from the optimization idea of Transformer performance improvement by stacking the ConvNeXt Blocks in the ratio of 3:3:9:3 as backbone, adding the big size kernel and other adjustments, upgrading the mean average precision (mAP) of the network model by 5%. Then, to maintain the original accuracy while reducing the number of parameters, a computationally reduced cheap operation is introduced, which employs a simple 3 * 3 convolution to achieve a low-cost acquisition of redundant feature maps, resulting in a reduction of 12% in parameter count while also increasing the mAP. Both theoretical analysis and experiments demonstrate the effectiveness of the improved network model.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":100,"string":"100"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":248,"string":"248"}}},{"rowIdx":249,"cells":{"question_id":{"kind":"string","value":"Jian Jiao"},"question":{"kind":"string","value":"Generate an abstract for the title \"Design of one-stop and on-demand remote sensing integrated services platform\" using the following items: Remote sensing, China, collaboration, platform, integrated services."},"answer":{"kind":"string","value":"Many research institutes in China have reached the consensus that remote sensing resource sharing and application expanding can be achieved by means of extensive and sustainable cooperation and collaboration. Considering the current status of remote sensing in China and some existing systems in the world, Quantitative Remote Sensing Integrated Services Platform (QRSISP) is recently proposed and researched to promote remote sensing service for public users, facilitate the development of the remote sensing industry and improve the ability to deal with the national disasters. This paper designs the architecture, subsystems and interfaces of QRSISP and describes the major service workflows. Through combining to the ecommerce, QRSISP has tried to change the traditional mode of remote sensing applications and provide one-stop and on-demand integrated services."},"correct_answer":{"kind":"string","value":"Many research institutes in China have reached the consensus that remote sensing resource sharing and application expanding can be achieved by means of extensive and sustainable cooperation and collaboration. Considering the current status of remote sensing in China and some existing systems in the world, Quantitative Remote Sensing Integrated Services Platform (QRSISP) is recently proposed and researched to promote remote sensing service for public users, facilitate the development of the remote sensing industry and improve the ability to deal with the national disasters. This paper designs the architecture, subsystems and interfaces of QRSISP and describes the major service workflows. Through combining to the ecommerce, QRSISP has tried to change the traditional mode of remote sensing applications and provide one-stop and on-demand integrated services."},"documents":{"kind":"list like","value":["Title: Smart active object: a new object-oriented programming paradigm for developing multithreaded applications\nYear: 2002\n\nAbstract: Multithreaded programming has been widely used nowadays, but developing mutlithreaded applications is still a tough task. To alleviate such kind of work we propose a new concept, Smart Active Object, an extension to the normal object in object-oriented technology. Smart Active Object runs concurrently with the main execution logic of the program, leveraging multithreading mechanisms and meanwhile leaves only sequential interfaces for programmers to insert application-specific parts, masking details of multithreading, which eventually enhances programming productivity. To support our claims, we design and implement a framework comprising a collection of cooperative Smart Active Objects for stateful applications, a typical problem in telecom world. Using this framework, we easily solve a toy problem, derived from the behavior of SIP stateful proxy servers within much shorter time than a conventional C version counterpart.","Title: Rimless wheel with asymmetric flat feet.\nYear: 2010\n\nAbstract: The purpose of this paper is to have a better understanding of the function of human flat foot. To analyze its dynamics, we propose a passive rimless wheel with asymmetric flat feet. The model has a point mass in center and massless spokes. The rigid asymmetric flat feet were equipped at the end of spokes. The walking process of this model which has \"heel-strike\" and \"toe-strike\" is similar to human walking which has two peaks of vertical contact force in one stride. The stability was analyzed through eigenvalues of the linearized return map. The energy efficiency was analyzed in two ways, one from CoM trajectory and collision angle, another one from speed and step length. The proposed model has faster walking speed, higher energy efficiency, but lower local stability, compared with regular rimless wheel. © 2010 IEEE.","Title: A Robust Boosting Regression Tree with Applications in Quantitative Structure-Activity Relationship Studies of Organic Compounds.\nYear: 2011\n\nAbstract: A regression tree (RT) was extensively utilized in quantitative structure activity relationship studies (QSAR), due to its inherently promising attributes. The issues of instability and inclination to overfitting and suboptima, however, often occur in RT. In the present study, a robust version of boosting was invoked to simultaneously improve the stability and generalization ability of RT, forming a new method called robust boosting regression tree (RBRT). RBRT works by sequentially employing the RT method to model the robustly reweighted versions of the original training set and then aggregating these resultant predictors via weighted median. The designed RBRT was applied to predict the bioactivities of flavoniod derivatives and the anti-HIV activities of HIV-1 inhibitors, compared with boosting RT (BRT) and RT. The results of these two data sets demonstrated that the introduction of robust boosting drastically enhances the stability and generalization ability of RT, and RBRT is superior to BRT in QSAR studies.","Title: A tactical intelligence production model of computer network self-organizing operations\nYear: 2010\n\nAbstract: In this paper, we define the concepts of target's information and intelligence activities for Computer Network Self-organizing Operations, propose a tactical intelligence production model of computer network self-organization operation and prove its reachability. In order to verify the model, we present the evaluating, analysis and interpreting algorithm based on rule-based reasoning. Then, we design and implement the tactical intelligence production prototype to verify the validity of the CNSOO-TIPM and algorithms. The experiment results show that the prototype provides timely and accurate intelligence information for the CNO decision and meets the most basic needs of cooperative operations between the CNO agents.","Title: Burst mode to strip-map mode SAR interferometry of ALOS PALSAR\nYear: 2010\n\nAbstract: A complete processing flow is proposed to implement burst mode to strip-map mode interferometry for ALOS PALSAR data. The processing flow is applied to an interferometric pair comprised of FBD (High Resolution mode [Dual polarization], belonging to strip-map mode) and WB1 (Wide observation mode, belonging to burst mode) mode of PALSAR. Interferometric products including differential interferometric phase and DEM are generated. The evaluation of these products shows satisfactory precision.","Title: The Application of BP Neural Network in the Fault Diagnosis of Rotating Machinery\nYear: 2011\n\nAbstract: BP neural network is effective for deaLing with non-Linear mapping which could satisfactorily describe the non-Linear relations between frequency character and diagnosis results. So the de-noising and feature extraction methods of rotating machinery is discussed in this paper, and a diagnosis model for rotating machinery based on BP neural network is proposed and set up. Then, emulates the model of diagnosis of BP neural network through using MATLAB. Experiment results show that the proposed method based on BP neural network has high practical value in the rotating machinery fault diagnosis.","Title: Modified particle swarm optimization algorithm for adaptively configuring globally optimal classification and regression trees.\nYear: 2009\n\nAbstract: The configuration of classification and regression trees (CART) used to include tree-growing by greedy recursive partitioning, which selects the splitting parameters (i.e., splitting variables and values) involved in tree, and tree-pruning, which aims to obtain a final tree of right size. This method is successful for most applications; however, it presents some well-known limitations and drawbacks, such as, less comprehensibility, inclination to overfitting, and suboptima. In the present study, the modified discrete particle swarm optimization method was invoked to adaptively configure the globally optimal CART (MPSOCART) via simultaneously selecting the optimal splitting parameters in CART and the appropriate structure of CART. A new objective function was formulated to decide the appropriate CART architecture and the optimum splitting parameters. The proposed MPSOCART was applied to predict the bioactivities of flavonoid derivatives and inhibitory activities of inhibitors of epidermal growth factor receptor tyrosine kinase, compared with partial least-squares and CART induced by greedy recursive partitioning. The comparison revealed that MPSO was a useful tool for inducing a globally optimal CART, which converges fast to the optimal solution and avoid overfitting in great extent.","Title: An Assessment of ScanSAR Interferometric Processing Using Full-Aperture Approach\nYear: 2014\n\nAbstract: Scanning synthetic aperture radar (ScanSAR) interferometry using full-aperture approach has been used in the geophysical community when a standard ScanSAR interferometric processor is not available. Although interferograms can routinely be produced as well, some concerns about the full-aperture processing still remain. In this letter, we assess the quality of the interferogram produced by this approach. After theoretical analyses, we compare interferograms produced by the full-aperture approach and the standard burst-by-burst approach. Comparison results show that the difference between the final interferograms produced by the two approaches is small. For the data processed, the mean value and standard deviation of the difference phase are 8.36 ×10-4 rad and 3.60 ×10-1 rad, respectively. These results confirm the availability of full-aperture processing for most of the geophysical applications using ScanSAR interferometry.","Title: ExpertRank: A topic-aware expert finding algorithm for online knowledge communities\nYear: 2013\n\nAbstract: With increasing knowledge demands and limited availability of expertise and resources within organizations, professionals often rely on external sources when seeking knowledge. Online knowledge communities are Internet based virtual communities that specialize in knowledge seeking and sharing. They provide a virtual media environment where individuals with common interests seek and share knowledge across time and space. A large online community may have millions of participants who have accrued a large knowledge repository with millions of text documents. However, due to the low information quality of user-generated content, it is very challenging to develop an effective knowledge management system for facilitating knowledge seeking and sharing in online communities. Knowledge management literature suggests that effective knowledge management should make accessible not only written knowledge but also experts who are a source of information and can perform a given organizational or social function. Existing expert finding systems evaluate one's expertise based on either the contents of authored documents or one's social status within his or her knowledge community. However, very few studies consider both indicators collectively. In addition, very few studies focus on virtual communities where information quality is often poorer than that in organizational knowledge repositories. In this study we propose a novel expert finding algorithm, ExpertRank, that evaluates expertise based on both document-based relevance and one's authority in his or her knowledge community. We modify the PageRank algorithm to evaluate one's authority so that it reduces the effect of certain biasing communication behavior in online communities. We explore three different expert ranking strategies that combine document-based relevance and authority: linear combination, cascade ranking, and multiplication scaling. We evaluate ExpertRank using a popular online knowledge community. Experiments show that the proposed algorithm achieves the best performance when both document-based relevance and authority are considered.","Title: Real Scene Oriented Chinese Text Automatic Proofreading Technology.\nYear: 2013\n\nAbstract: Traditional Chinese text automatic proofreading technology is mainly focused on one or more pre-set error types, the proofreading performance in a real scene needs to be improved. This paper proposes a real scene oriented Chinese text proofreading system model for Chinese text automatic proofreading. Real scene oriented Chinese text automatic proofreading strategy is provided after analyzing performance requirements of automatic proofreading system for the real scene. The model is expected to provide new thoughts for future development of proofreading for Chinese text. © 2013 Springer-Verlag.","Title: Application for Artificial Bee Colony Algorithm in Migration of Mobile Agent\nYear: 2010\n\nAbstract: The traveling agent problem is a complex combinatorial optimization problem, which solves the problem of planning out an optimal migration path according to the tasks when agents migrate to several hosts in the shortest time. Evolutionary algorithm such as ACO has the well characteristic for heuristic search and robustness. But it has the limitation for the stagnation in the searching. This problem will cause the agent wasting more time in tasking. To avoid it an improved algorithm based on artificial bee colony is introduced. This algorithm uses three kinds of roles: Blaze, Reconnaissance and Follow to routing and finishing the tasks. Agents of the role exchange the information to adopt their own path. The whole group can get the more efficiency path during migration. The experiments show this algorithm has better results in some aspects which needs less times and load for host comparing with the other evolutionary algorithm.","Title: On the Phase Compensation of Short ScanSAR Burst Focused by Long Matched Filter for Interferometric Processing\nYear: 2014\n\nAbstract: Scanning synthetic aperture radar (ScanSAR) uses a burst technique to image very large swaths and is widely used in spaceborne SARs. Many algorithms have been proposed to focus ScanSAR burst with its phase preserved so that the focused burst can be used in interferometry to acquire large scale geophysical information, such as land deformation and digital elevation model. However, nearly all of the algorithms leave the focused burst with an additional quadratic phase term that will affect subsequent interferometric processing in the case of short burst. With this phase term, the spectrum of the focused burst is altered according to the principle of stationary phase. Therefore, some processing, such as bandpass filtering, cannot produce desired results if routinely performed. To avoid the effects of the phase term and the nonstationary azimuth spectrum of the burst, a phase compensation scheme is suggested, combining with current focusing algorithms. Simulation experiments are designed to show the effects of the phase term on bandpass filtering. These effects are further verified by a few experiments using real SAR data in unsynchronized signal removal that is frequently required in repeat-pass ScanSAR interferometry. The new phase compensation scheme is tested in real SAR data experiments and works well.","Title: Vehicle defect discovery from social media\nYear: 2012\n\nAbstract: A pressing need of vehicle quality management professionals is decision support for the vehicle defect discovery and classification process. In this paper, we employ text mining on a popular social medium used by vehicle enthusiasts: online discussion forums. We find that sentiment analysis, a conventional technique for consumer complaint detection, is insufficient for finding, categorizing, and prioritizing vehicle defects discussed in online forums, and we describe and evaluate a new process and decision support system for automotive defect identification and prioritization. Our findings provide managerial insights into how social media analytics can improve automotive quality management.","Title: Calibration of airborne interferometric SAR data by external dem without artificial calibrators\nYear: 2012\n\nAbstract: It is necessary to calibrate interferometric system parameters in order to achieve high accuracy of DEM. The traditional calibration method use a lot of ground artificial calibrators as ground control points. However, the number of calibrators is limited and the distribution is difficult in some mountainous areas. The paper presents a calibration method based on an external DEM without any artificial calibrators. A simulated SAR image was generated with the aid of this reference DEM and a number of tie points were selected to be ground control points. This calibration method can improve the DEM accuracy, and this paper also illustrates its efficient application to airborne interferometric SAR data.","Title: What's buzzing in the blizzard of buzz? Automotive component isolation in social media postings\nYear: 2013\n\nAbstract: In the blizzard of social media postings, isolating what is important to a corporation is a huge challenge. In the consumer-related manufacturing industry, for instance, manufacturers and distributors are faced with an unrelenting, accumulating snow of millions of discussion forum postings. In this paper, we describe and evaluate text mining tools for categorizing this user-generated content and distilling valuable intelligence frozen in the mound of postings. Using the automotive industry as an example, we implement and tune the parameters of a text-mining model for component diagnostics from social media. Our model can automatically and accurately isolate the vehicle component that is the subject of a user discussion. The procedure described also rapidly identifies the most distinctive terms for each component category, which provides further marketing and competitive intelligence to manufacturers, distributors, service centers, and suppliers.","Title: ScanSAR interferometric processing using existing standard InSAR software for measuring large scale land deformation\nYear: 2013\n\nAbstract: Scanning synthetic aperture radar (ScanSAR) mode is an efficient way to map large scale geophysical phenomena at low cost. The work presented in this paper is dedicated to ScanSAR interferometric processing and its implementation by making full use of existing standard interferometric synthetic aperture radar (InSAR) software. We first discuss the properties of the ScanSAR signal and its phase-preserved focusing using the full aperture algorithm in terms of interferometry. Then a complete interferometric processing flow is proposed. The standard ScanSAR product is decoded subswath by subswath with burst gaps padded with zero-pulses, followed by a Doppler centroid frequency estimation for each subswath and a polynomial fit of all of the subswaths for the whole scene. The burst synchronization of the interferometric pair is then calculated, and only the synchronized pulses are kept for further interferometric processing. After the complex conjugate multiplication of the interferometric pair, the residual non-integer pulse repetition interval (PRI) part between adjacent bursts caused by zero padding is compensated by resampling using a sinc kernel. The subswath interferograms are then mosaicked, in which a method is proposed to remove the subswath discontinuities in the overlap area. Then the following interferometric processing goes back to the traditional stripmap processing flow. A processor written with C and Fortran languages and controlled by Perl scripts is developed to implement these algorithms and processing flow based on the JPL/Caltech Repeat Orbit Interferometry PACkage (ROI_PAC). Finally, we use the processor to process ScanSAR data from the Envisat and ALOS satellites and obtain large scale deformation maps in the radar line-of-sight (LOS) direction.","Title: Design and realization of local oscillator for VHF survival receiver.\nYear: 2010\n\nAbstract: Local oscillator is an important device for survival radio system receiver. In this paper, a simple design and flexible configuration, local oscillator using DDS (Direct Digital Frequency Synthesis) technology has been designed and realized. Concerning with double conversion superheterodyne RF Front-End for the receiver, the local oscillator is to generate two channel sinusoidal signals whose frequencies are 130 and 70 MHz separately. The local oscillator consists of a CPLD (complex programmable logic device), two DDS chips, two crystal oscillators, and two low pass filters. The CPLD serving as the controller controls the operation of two DDS chips. The control parameters are stored in the UFM (User Flash Memory) block embedded in the CPLD. The complexity of the circuit is reduced effectively by synchronous serial communication protocol scheme applied between the CPLD and two DDS chips. Simulation and experiment results show that the logic circuit design of the controller is correct and the local oscillator has a good performance. © 2010 IEEE.","Title: A New Method of Removing Unsynchronized Signal for ScanSAR Interferometry\nYear: 2013\n\nAbstract: We have analyzed most of the commonly used burst-mode focusing algorithms and chose the one that can be easily combined with unsynchronized-signal removal. In order to remove the unsynchronized signal in scanning synthetic aperture radar (ScanSAR) interferometry, we calculate the burst synchronization using satellite state vectors at first. Then, based on the focusing algorithm chosen and the synchronization calculated, we propose a method to remove the unsynchronized signal. The method rejects the unsynchronized phase and keeps all of the magnitude information. It has been tested with simulated Envisat Advanced Synthetic Aperture Radar ScanSAR data, and the result demonstrated that the method could effectively remove the unsynchronized signal for ScanSAR interferometric processing.","Title: Geometric calibration and geolocation of airborne SAR images\nYear: 2012\n\nAbstract: The research focuses on airborne SAR geometric calibration. Based on Range-Doppler (RD) model, mathematical model of airborne SAR image pixel direct geolocation was derived and objective calibration parameters were determined. A whole geometric calibration procedure was proposed, whose critical techniques had been studied. Through the experiment in Guizhou province, China, the calibration parameters were calculated and validated.","Title: Investigating co-seismic deformation of the 2008 Wenchuan earthquake with ALOS SCANSAR interferometric observations.\nYear: 2010\n\nAbstract: On May 12th, 2008, a destructive earthquake of magnitude 8.0 struck Wenchuan. The seismic region is located at the transition zone between Qinghai-Tibet Plateau and the Sichuan Basin, which has a complex geological tectonic background. In this paper, we intend to investigate the Wenchuan earthquake using the Differential Interferometric SAR(D-InSAR) technique. Due to the large scale of the crustal deformation affected by the disastrous earthquake, SCANSAR images show more advantages than conventional strip-map mode images. And taking account the vegetation conditions, the L band images are suitable than the C band images for our study. Therefore, we choose to use ALOS SCANSAR interferometric observations to obtain a preliminary co-seismic displacement filed of the Wenchuan earthquake.","Title: Determination of vertical antenna pattern of high-resolution airborne SAR and radiometric calibration\nYear: 2012\n\nAbstract: An external calibration experiment was held for an airborne SAR. The paper describes the calibration experiment that uses a series of trihedral corner reflectors to calibrate the high-resolution SAR images, including antenna pattern correction and absolute radiometric calibration. In this paper, we specifically address the determination of vertical antenna pattern with multi-flight SAR imaging geometry, and discussion of the absolute calibration methods. First, three images acquired with variable off-nadir angle from 67.9~78.3, 70.9~78.4, and 72.5~79.8 degree respectively are combined to measure the antenna pattern with off-nadir angle from 67~80 degree. And then three images were relatively calibrated on the uniform standard based on the uniform antenna pattern. Secondly, the absolute calibration factor is inferred with two methods called average method and linear regression method, and the result is compared and analyzed. The experimental results show that our calibration method with several images together to acquire the large antenna pattern is feasible. And these images achieve a uniform relative calibration even though the different images have different imaging geometry and radiometric characteristics. After absolute calibration, the estimated RCS of each corner reflector basically reached agreement with the actual RCS, and the estimated error from the calibrated image for most of corner reflectors is less than 1.0dB.","Title: A Novel Hybrid Method To Unwrapping Interferometric Phase\nYear: 2004\n\nAbstract: Phase Unwrapping is the most difficult and unavoidable problem in the interferometric synthetic aperture radar (InSAR) processing procedures. lntensive researches have been done and the methods proposed were summaried into two categories: path following and minimum norm. Unwrapping result by path following is congruent with wrapped phase and require less time and memory. While minimum norm method usually could not obtain congruent result directly and take more Computing resource. Weighting could improve base unwrapping result much if the suspicious region could be correctivelty separated out by weighting function. However, common used weighting such as coherence or phase gradiant could not serve this purpose very well. In this paper, we proposed a novel method to unwrap phase, which combined the advantages of both categories, and set weight based on phase unwrapping consistence. We demonstrated the method with real InSAR phase. The unwrapping result showed the novel method could recover the dynamic range of phase than least square method while keep correct trend.","Title: Simulation And Analysis Of Microwave Emissivity And Opacity Of Winter Wheat By Radiation Transfer Method\nYear: 2003\n\nAbstract: Measuring soil moisture is very important for monitoring global water cycle. In past years more than two decades, measuring soil moisture by passive and active microwave remote sensing has been intensively researched [3, 4, 6, 7]. The significant advancements has been made in measuring soil moisture in bare soil field or less vegetation covered region. To measure soil moisture with vegetation cover, vegetation emissivity and opacity have to be included as two parameters to character radiation in vegetation layer. In this paper, we reviewed the phenomenological model to treat radiation transfer in media comprised of vegetation and underlying soil surface. And then simulation of vegetation emissivity and opacity based on radiation transfer theory and combined with input of geometrical parameters and water content measured in winter wheat field was presented. Finally, the relationships between them, in particular of different frequencies and polarization, were been dug out and examined.","Title: A dynamic stochastic frontier model to evaluate regional financial efficiency: Evidence from Chinese county-level panel data.\nYear: 2015\n\nAbstract: Studies have widely used stochastic frontier models to assess financial efficiency; however, traditional static approaches do not take dynamic characteristics of financial systems into account. This article develops a dynamic stochastic frontier model to evaluate regional financial efficiency and provides an empirical test of the model by using panel data of 62 Chinese counties during the 2001–2010 period. The model measures the dynamic impact of the input–output variables and environmental variables on financial efficiency, and allows for the separation of technical change from the change in technical efficiency. The results show that the dynamic model provides a better fit to the data than the static model. In addition, a gradient difference emerges in the regional financial efficiency among the six major regions of China. The results offer practical implications for the development of regional financial services in China, as well as other developing countries and emerging economies.","Title: Improvement of PS-InSAR atmospheric phase estimation by using WRF model\nYear: 2014\n\nAbstract: As a component of interferometric phase, atmospheric phase influences accuracy of millimetric land deformation measurement. Though Atmospheric Phase Screen (APS) can be estimated by Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technology, they are pseudo without consideration of actual atmospheric state and topography. This paper researches into ineffective separation of atmospheric phase in PS-InSAR methods when applied to extended cloudy area, and proposes an improved PS-InSAR processing flow by introducing Weather Research Forecast (WRF) simulations to remove atmospheric phase before interferometric phase analysis of PSI technique to obtain accurate land deformation velocity.","Title: A new user-oriented remote sensing information service model based on integrated platform\nYear: 2014\n\nAbstract: In this paper, we propose a novel user-oriented information service model for the development trend of remote sensing information service industrialization. Traditional remote sensing information service model is often a typical product-oriented service model, which is unable to make the most use of the existing resource nowadays. From the perspective of information service model, this research analyzes the defects of traditional remote sensing service model and the technical development of remote sensing service, puts forward the new remote sensing information service model based on integrated platform, and notes its advantages than the traditional model. At last, this paper explores the possible technical difficulties for the implement of the new service model.","Title: Fusion of multi-frequency interferometric results by using Kalman filter to generate high quality DEM\nYear: 2014\n\nAbstract: Using conventional two-pass interferometry to generate DEM with high frequency SAR data may be confronted with the problem of poor coherence in areas covered by dense vegetation, while DEM generated from low frequency SAR data interferometry is less sensitive to the topographic relief. Therefore, this article aims at generating high quality DEM by fusing multi-frequency interferometric results obtained from two-pass interferometry by using Kalman filter. Meanwhile, a process of coregistration of multi-frequency SAR data which are of different pixel sizes and imaging geometries is proposed. And data from Envisat ASAR and TerraSAR-X are used for case study and the accuracy of fused DEM are verified by ASTER GDEM.","Title: Research of InSAR atmospheric correction using WRF model simulated result and MERIS product\nYear: 2012\n\nAbstract: Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to study the co-seismic displacement field of earthquakes. With the development of D-InSAR technique, the removal of the atmospheric effect has been the main focus points of research to reduce the InSAR LOS displacement measurement error. Previous studies have shown that the MERIS water vapor product is one of the best choices for ASAR data to reduce the atmospheric effect in cloudless weather conditions. In this paper, we use the combination of the simulated results with WRF model and MERIS water vapor product to reduce the atmospheric effect in some cloudy weather condition.","Title: Error correction method based on data transformational GM(1, 1) and application on tax forecasting.\nYear: 2015\n\nAbstract: This paper provides an overview of the existing prediction methods, and then put forward a new approach for the improvement of prediction accuracy by introducing error correction. The characteristics of this method are to make full use of some valuable information contained in the error value. Its main idea is that the accelerated translation transforms and weighting mean value generating transforms are introduced to deal with prediction error sequence, so as to analyze the distribution of the prediction error and construct the error correction method based on data transformational GM(1,1),which is used to predict the subsequent error. And then, the predictive value of error is used to adjust the initial predicted revenue. After data transformation, the new sequences are much less volatile than before, and the smooth degree also becomes small. And to be more credible, case study verifies that this method has a better fitting effect and higher prediction precision. An error correction method is proposed to improve forecasting accuracy.This algorithm is integrated with LS-SVR and data transformation GM(1,1).This method emphasizes on the importance of making full use of error informationProposed algorithm is well suited for the characteristics of prediction error.The approach is superior to traditional forecasting methods. Accurate tax forecast is very important to carry on the macroscopic regulation efficiently under the market economy. However, experience shows that it is very difficult to improve the accuracy of forecasting by setting up a single forecasting model. This article describes the deficiencies of the present forecasting methods and puts forward a new approach to improve the accuracy of prediction by introducing error correction. First, this paper carries out initial prediction of tax revenue by using the LS-SVR model. Second, the accelerated translation transform and weighting mean value generating transform are introduced to process the error sequence. On the basis of the processed data, the error predictive method based on data transformational GM(1,1) is constructed and predicts the subsequent error. Third, the correction of preliminary prediction values is calibrated. The case study based on Chinese tax revenue during the last 30 years shows that the presented approach improves the accuracy of forecasting significantly compared with the prediction accuracy before correction, and then the validity of the model is verified.","Title: A Novel Approach To Building Collapse Detection From Post-Seismic Polarimetric Sar Imagery By Using Optimization Of Polarimetric Contrast Enhancement\nYear: 2015\n\nAbstract: A novel approach is proposed in this paper for earthquake-induced building collapse extraction based on the optimization of polarimetric contrast enhancement (OPCE). This method can realize a quick building damage assessment since the data it requires is one post-event fully polarimetric Synthetic Aperture Radar (PolSAR) image. In this method, collapsed building is recognized as clutter and the optimal polarization states are determined based on building samples with different orientation angles. For comparison, another contrast enhancement methodology, polarization synthesis technology is also utilized. We tested these two methods by using one Radasat-2 PolSAR image from Yushu earthquake in Qinghai province of China occurred in 2010. Results were validated by manual interpretation results of very high resolution (VHR) optical image. Experiments shows that collapsed building detection accuracy of OPCE method can be 66.53% in average, which is higher than that of polarization synthesis technology (42.7%) for the reason that building orientation is considered in the data processing of OPCE method.","Title: Study On The Production Cost Pricing Model Of Quantitative Remote Sensing Products\nYear: 2015\n\nAbstract: Since the forming of sustainable business models of remote-sensing products and services will be an inevitable development trend, it is necessary to design the specific and rational pricing model for quantitative remote sensing products (QRSPs). Based on the production procedures, this paper presents a production cost pricing model of QRSPs, to achieve the conversion from abstract factors of production cost to the pricing parameters that can be operated in the actual cost pricing. The pricing model is devised as the addition model so that it can fulfill the diverse acquirements of customized production. The valuation of common products of China Remote Sensing Network indicated that the pricing model could be well-operated in theory.","Title: High Precision Airborne Sar Geometric Calibration And Geolocation Based On An Improved Near Range Model\nYear: 2015\n\nAbstract: The research focuses on high precision airborne SAR geometric calibration (GC) and geolocation (GL) on the condition of long flight time.The experiment was conducted in Inner Mongolia, China, and based on image pixels' GL model, calibration parameters and procedure proposed in literature [1], two systematic parameters (near range R-0 and slant range resolution rho(r)) were calculated and validated. But, compared with the method in literature [1], improvements were mainly made on two aspects: firstly, Cubic spline rather than simple polynomial was used in this research to fit POS data so as to get a more accurate SAR antenna's position and velocity at zero Doppler time; secondly, through analysis of distribution of corner reflectors' GL errors, slant range (or near range) error was identified as main factor affecting GL, then an improved near range model was computed, validated and used to improve the accuracy of GL.Through the experiment in Inner Mongolia, the accuracy of GL in X and Y direction was 1m and 0.26m respectively, and after introducing the improved near range model, the accuracy of GL can be increased by about 10%.","Title: A New Method For Building Collapse Detection Jointly Using Interferometric And Polarimetric Information\nYear: 2015\n\nAbstract: Earthquake is one of the most catastrophic disasters to affect mankind especially in urban areas. Reliable and fast collapsed building detection is vitally important to timely rescue and scientific decision making. A modified detection method for collapsed buildings is proposed in this paper by jointly using interferometric information and polarimetric information. The method was tested on two single-polarimetric ALOS PALSAR images and one fully polarimetric Radarsat-2 image from Yushu earthquake in Qinghai province of China occurred in 2010. After compared with manual interpretation results of very high resolution (VHR) optical image, collapsed building detection accuracy can be 72.77%. The accuracy is improved by about 30% compared with that of only coherence based method.","Title: Deep Crossing: Web-Scale Modeling without Manually Crafted Combinatorial Features\nYear: 2016\n\nAbstract: Manually crafted combinatorial features have been the \\\"secret sauce\\\" behind many successful models. For web-scale applications, however, the variety and volume of features make these manually crafted features expensive to create, maintain, and deploy. This paper proposes the Deep Crossing model which is a deep neural network that automatically combines features to produce superior models. The input of Deep Crossing is a set of individual features that can be either dense or sparse. The important crossing features are discovered implicitly by the networks, which are comprised of an embedding and stacking layer, as well as a cascade of Residual Units. Deep Crossing is implemented with a modeling tool called the Computational Network Tool Kit (CNTK), powered by a multi-GPU platform. It was able to build, from scratch, two web-scale models for a major paid search engine, and achieve superior results with only a sub-set of the features used in the production models. This demonstrates the potential of using Deep Crossing as a general modeling paradigm to improve existing products, as well as to speed up the development of new models with a fraction of the investment in feature engineering and acquisition of deep domain knowledge.","Title: Force Maintenance Accuracy Using a Tool: Effects of Magnitude and Feedback.\nYear: 2016\n\nAbstract: The ability to precisely produce a force via a hand-held tool is crucial in fine manipulations. In this paper, we study the error in maintaining a target force ranging from 0.5 to 5 N under two concurrent feedback conditions: pure haptic feedback (H), and visual plus haptic feedback (V + H). The results show that absolute error (AE) increases along with the increasing force magnitudes under both f...","Title: A Geocoding Method For Sar Image Based On Tin Lookup Table\nYear: 2016\n\nAbstract: A geocoding method for SAR image based on Triangulated Irregular Network (TIN) lookup table is proposed in this paper. Firstly, TIN DEM is generated from Grid DEM. Then, each node in TIN DEM is geocoded by Range-Doppler model to produce a TIN lookup table. Finally, geocoded image is resampled by TIN lookup table. Experimental results show TIN lookup table can reduce file size with losing less precision, which compared with original Grid lookup table. Although TIN lookup table takes some time to create TIN DEM from Grid DEM, it takes less time than original lookup table in geocoding process. So it could save running time for large number of SAR images geocoding in the same area. TIN lookup table can balance between precision and file size, when its height tolerance approximately is less than accuracy of DEM products.","Title: Measurement Crustal Movement Along Altyn Tagh Fault By Using Multimode Insar Time Series Analysis\nYear: 2016\n\nAbstract: High-coherent pixels detection and spatial coverage restriction are the key difficulties when applying the InSAR time series analysis in Altyn Tagh Fault (ATF) system based on stripmap SAR data. In this paper, a modified InSAR time series analysis method combining PS and DS is presented in order to increase the number of selected high-coherent pixels. Then a displacement velocities merging strategy by fitting least squares surfaces is proposed, which could decrease the velocities differences in overlap area between adjacent stripmap SAR tracks, so as to acquire the deformation results of the whole research area. Moreover, in order to avoid the merging problem caused by the inconsistent measurements between adjacent stripmap SAR tracks, processing strategies of ScanSAR PS-InSAR and ScanSAR SBAS are presented respectively. All of the methodology we proposed have been applied to the crustal movement measurement along the west section of ATF and reliable results have been acquired.","Title: A New Framework Of Building Collapse Extraction Based On Azimuth Time-Frequency Analysis\nYear: 2016\n\nAbstract: Rapidly obtaining building damage information after the earthquake is vitally important to earthquake rescue and decision making. In this paper, we propose a new framework of building collapse extraction by combining polarimetric information and azimuth time-frequency analysis. The proposed framework consists of two main steps, i.e. open area removal and intact building identification. In the first step, we introduce the Shannon entropy to polarimetric parameters derived from H/Lambda/alpha decomposition to remove open areas. Since intact buildings with orientation angles present a similar scattering mechanism to collapsed buildings, it seriously hampers the building collapse extraction accuracy. To solve this problem, in the second step we try to use azimuth time-frequency analysis to eliminate this deficiency. In the azimuth direction, sub-aperture images are obtained by spectrum splitting, which corresponds to observe the targets from different azimuth look angles. The nonstationary discrimination method is used combined with the SPAN parameter to identify intact buildings including intact buildings with orientation angles. The feasibility of the second step has been demonstrated by using E-SAR PolSAR data. The potential advantage of the proposed framework when we apply it to the earthquake-induced building collapse extraction includes that only one post-earthquake polarimetric SAR (PolSAR) image is needed. Moreover, orientated intact buildings can be identified and the final accuracy of building collapse extraction can be probably improved as a result.","Title: Quantitative Analysis Of The Water Vaopr Effects On The Interferometric Measurements\nYear: 2016\n\nAbstract: The water vapor plays an important role on the microwave propagation. Plenty of methods to reduce its effects in the differential InSAR technique have been put forward, such as using MERIS, MODIS, GPS and the weather models. In order to analyze the water vapor effects quantitatively, we selected several time-series related Envisat ASAR images with their corresponding synchronous MERIS Full Resolution water vapor products. First of all, we analyze the quantitative relationship between the water vapor delay and the local elevation and find that there is no obvious linear correlation between water vapor and elevation. Then, we make a comparison between the InSAR measurements without water vapor correction and measurements with water vapor correction. The results indicate that the removal of the water vapor delay and the baseline refinement are coupled together. And at the same time, the influence of water vapor can lead to error of at least 10 mm.","Title: Throughput-Optimal Scheduling for Multi-Hop Networked Transportation Systems With Switch-Over Delay.\nYear: 2017\n\nAbstract: The emerging connected-vehicle technology provides a new dimension for developing more intelligent traffic control algorithms for signalized intersections. An important challenge for scheduling in networked transportation systems is the switchover delay caused by the guard time before any traffic signal change. The switch-over delay can result in significant loss of system capacity and hence needs to be accommodated in the scheduling design. To tackle this challenge, we propose a distributed online scheduling policy that extends the well-known Max-Pressure policy to address switch-over delay by introducing a bias factor favoring the current schedule. We prove that the proposed policy is throughput-optimal with switch-over delay. Furthermore, the proposed policy remains optimal when there are both connected signalized intersections and conventional fixed-time ones in the system. With connected-vehicle technology, the proposed policy can be easily incorporated into the current transportation systems without additional infrastructure. Through extensive simulation in VISSIM, we show that our policy indeed outperforms the existing popular policies.","Title: On the Pixel Expansion of Visual Cryptography Scheme.\nYear: 2017\n\nAbstract: In this paper, we first follow Ateniese et al.'s work that provides upper bounds of the pixel expansion of visual cryptography schemesVCSs for more kinds of graph access structures, in which we require that a subset of parties can determine the secret if they contain an edge of the graph G. The constructive upper bounds are derived by the graph decomposition technique. Then we generalize Ateniese et al.'s method of comparing the optimal pixel expansion of VCSs with two different access structures.","Title: Absolute and discrimination thresholds of a flexible texture display\nYear: 2017\n\nAbstract: We present a flexible tactile interface, FlexTouch, for simulating texture of fabrics. The FlexTouch displays virtual texture on fingertips based on electrovibration principle. To exam human factors in using FlexTouch, we measured absolute detection thresholds of input voltage with respect to frequencies ranging from 30 to 300 Hz. The measured thresholds formed a U-shaped curve indicating a minimum value of 23 Vpp at the frequency of 169 Hz. We then measured the just-noticeable-differences (JNDs) of the voltage amplitudes ranging from 71 to 225 V at the most sensitive frequency, i.e. 169 Hz. The result suggests that the JNDs depend linearly on the amplitude of stimulus signal. These measures provide guidelines to design interfaces and applications using FlexTouch.","Title: Rate-Compatible Transmission Schemes Based on Parallel Concatenated Punctured Polar Codes.\nYear: 2017\n\nAbstract: In this paper, an improved random puncturing pattern of polar codes is proposed, where only the frozen bits can be selected to puncture. Compared to the existing random puncturing schemes, our improved random puncturing scheme can achieve 0.2-1dB decoding performance improvement. Then, an optimized rate-compatible hybrid automatic repeat request (HARQ) transmission scheme is proposed based on parallel concatenated punctured (PCP) polar codes. By analyzing the overhead of the previous successful decoded coding block in our rate-compatible HARQ scheme, two methods of determining the optimal initial code-rate of each new PCP polar coding block are proposed over a time-varying channel. Simulation results show that the average number of retransmissions is about 1.5 times in our proposed rate-compatible HARQ schemes with a 2-level PCP polar encoding construct, which reduces half of the average number of retransmissions than the existing rate-compatible polar coding scheme.","Title: Resilience Optimization for Complex Engineered Systems Based on the Multi-Dimensional Resilience Concept.\nYear: 2017\n\nAbstract: Most traditional engineered systems are designed with a passive and fixed reliability capability and just required to achieve a possibly low level of failure occurrence. However, as the complexity at spatial-temporal scales and integrations increases, modern complex engineered systems (CESs) are facing new challenges of inherent risk and bottleneck for a successful and safe operation through the system life cycle when potential expected or unexpected disruptive events happen. As a prototype for ensuring the successful operation of inherently risky systems, resilience has demonstrated itself to be a promising concept to address the above-mentioned challenges. A standard multi-dimensional resilience triangle model is first presented based on the concept of the three-phase system resilience cycle, which can provide a theoretical foundation for indicating the utility objectives of resilience design. Then, the resilience design problem for CESs is proposed as a multi-objective optimization model, in which the three objectives are to maximize the survival probability, to maximize the reactive timeliness and to minimize the total budgeted cost. Furthermore, the proposed multi-objective optimization programming is solved based on the efficient multi-objective evolutionary algorithm NSGA-II. Finally, the effectiveness of the proposed models and solving procedure is illustrated with an engineered electro-hydrostatic aircraft control actuator resilience design problem, a comparative analysis on the case study is also carried out with respect to previous works. This work can provide an effective tradeoff foundation to improve the resilience of CESs.","Title: Bounds on the error probability of finite-length RaptorQ codes.\nYear: 2017\n\nAbstract: Massive machine-to-machine (mM2M) communication requires data transmission in short packets, but at present, the theory of short length code design and optimazation is still incompletely. In this paper, we analyze the maximum likelihood (ML) decoding failure probability (DFP) of finite length RaptorQ codes, and propose a theoretical performance bound of DFP on the RaptorQ codes under ML decoding algorithm by investigating the rank of the product of two random coefficient matrices. Moreover, we verify the accuracy of derived theoretical bounds through the Monte Carlo simulations over varied Galois field order. The high accuracy bounds can be used to design near-optimum RaptorQ codes with short and moderate lengths.","Title: Design and analysis of LTP-HARQ transmission scheme in OSTBC-MIMO systems for SINs.\nYear: 2017\n\nAbstract: Recently, distributed/virtual multiple-input multiple-output (MIMO) technology over satellites have attracted considerable research interest due to the development of Ka-band high throughput satellites (HTS) and space information networks (SINs). In this paper, a novel performance analysis framework is proposed for MIMO with orthogonal space-time block coding (OSTBC) under Licklider transmission protocol (LTP) for emerging SINs, where we derive the closed-form expressions of the mean number of transmission rounds by using Laplace transform for reliable data delivery in automatic repeat request (ARQ) and hybrid-ARQ (HARQ) schemes. Furthermore, we derive the throughput expressions for lossless-and truncated-(H)ARQ schemes, and obtain the maximum throughput value on information rate. We also investigate the file delivery time in LTP over Rayleigh and Rician fading channels. Simulations results are provided to demonstrate the validity of our theoretical results, and show the effect of antenna number on the system performance.","Title: Efficient HARQ scheme based on rate-compatible punctured polar codes.\nYear: 2017\n\nAbstract: In this paper, an optimized parallel concatenated punctured polar (OPCPP) coding scheme is designed to realise the rate-compatible property of polar codes. First, an improved random puncturing pattern of polar codes is proposed to achieve better performance than the random puncturing scheme, which can obtain about 0.2–1dB better than the random puncturing scheme. Then, by analyzing the performance of HARQ transmission scheme via OPCPP coding blocks over slow fading channels, the optimal initial code rate of each new OPCPP coding block can be determined by the overhead of the previous successful decoded coding block. Simulation results show that the mean number of retransmissions in our proposed rate-compatible HARQ scheme is about 1.5 times with the encoding construct of a 2-level OPCPP codes, which can reduce half of the number of retransmissions than the existing rate-compatible polar coding scheme.","Title: Behavior Intention Derivation of Android Malware Using Ontology Inference.\nYear: 2018\n\nAbstract: Previous researches on Android malware mainly focus on malware detection, and malware's evolution makes the process face certain hysteresis. The information presented by these detected results (malice judgment, family classification, and behavior characterization) is limited for analysts. Therefore, a method is needed to restore the intention of malware, which reflects the relation between multiple behaviors of complex malware and its ultimate purpose. This paper proposes a novel description and derivation model of Android malware intention based on the theory of intention and malware reverse engineering. This approach creates ontology for malware intention to model the semantic relation between behaviors and its objects and automates the process of intention derivation by using SWRL rules transformed from intention model and Jess inference engine. Experiments on 75 typical samples show that the inference system can perform derivation of malware intention effectively, and 89.3% of the inference results are consistent with artificial analysis, which proves the feasibility and effectiveness of our theory and inference system.","Title: Performance Analysis of Space Information Networks with Backbone Satellite Relaying for Vehicular Networks.\nYear: 2017\n\nAbstract: Space Information Network (SIN) with backbone satellites relaying for vehicular network (VN) communications is regarded as an effective strategy to provide diverse vehicular services in a seamless, efficient, and cost-effective manner in rural areas and highways. In this paper, we investigate the performance of SIN return channel cooperative communications via an amplify-and-forward (AF) backbone satellite relaying for VN communications, where we assume that both of the source-destination and relay-destination links undergo Shadowed-Rician fading and the source-relay link follows Rician fading, respectively. In this SIN-assisted VN communication scenario, we first obtain the approximate statistical distributions of the equivalent end-to-end signal-to-noise ratio (SNR) of the system. Then, we derive the closed-form expressions to efficiently evaluate the average symbol error rate (ASER) of the system. Furthermore, the ASER expressions are taking into account the effect of satellite perturbation of the backbone relaying satellite, which reveal the accumulated error of the antenna pointing error. Finally, simulation results are provided to verify the accuracy of our theoretical analysis and show the impact of various parameters on the system performance.","Title: A Novel High-Rate Polar-Staircase Coding Scheme.\nYear: 2018\n\nAbstract: The long-haul communication systems can offer ultra high-speed data transfer rates but suffer from burst errors. The high-rate and high-performance staircase codes provide an efficient way for long-haul transmission. The staircase coding scheme is a concatenation structure, which provides the opportunity to improve the performance of high-rate polar codes. At the same time, the polar codes make the staircase structure more reliable. Thus, a high-rate polar-staircase coding scheme is proposed, where the systematic polar codes are applied as the component codes. The soft cancellation decoding of the systematic polar codes is proposed as a basic ingredient. The encoding of the polar-staircase codes is designed with the help of density evolution, where the unreliable parts of the polar codes are enhanced. The corresponding decoding is proposed with low complexity, and is also optimized for burst error channels. With the well designed encoding and decoding algorithms, the polar-staircase codes perform well on both AWGN channels and burst error channels.","Title: Social-Aware D2d Caching Content Deployment Strategy Over Edge Computing Wireless Networks\nYear: 2018\n\nAbstract: Caching the popular files in mobile terminal equipments and transferring those files via Device-to-Device (D2D) communication technology can offload the traffic from the Base Station(BS) over edge computing wierless network. The user equipments(UE) are mobile and the D2D communication links may drop any instant. In addition, UEs are carried by people with social attributes. Considering those information about mobile terminals when we study the D2D caching content deployment strategy can improve the caching efficiency. In order to reduce the probability of requesting files from BS, we design an efficient social-aware caching content deployment strategy, which includes the community discovery mechanism, the caching nodes selection algorithm and the file caching probability determination algorithm. Simulation experiments are provided to prove that our D2D caching content deployment strategy can improve the traffic offload rate in edge computing wireless networks.","Title: Availability Analysis and Optimal Design of Multistate Weighted k-Out-of-n Systems With Component Performance Requirements.\nYear: 2018\n\nAbstract: As one of the most typical multistate systems, weighted k-out-of-n system has been extensively studied in recent years. This paper presents a new kind of multistate weighted k-out-of-n system, which simultaneously considers performance requirements of each component and the system performance (cumulative performance threshold of all components). Then, we establish a new dynamic availability model by combining the Markov process and universal generating function. Moreover, an optimal design is proposed to achieve a tradeoff between system reliability/availability and cost. Non-dominated sorting genetic algorithm-II is used to optimize the probability and performance of components in different states. Finally, an example is illustrated to evaluate system availability and optimize component design. The optimization design can be referred as an optimal standard in system update.","Title: A Smart Post-Rectification Algorithm Based on an ANN Considering Reflectivity and Distance for Indoor Scenario Reconstruction.\nYear: 2018\n\nAbstract: Indoor scene reconstruction is important for robot positioning and navigation in scenario reconstruction, especially in constructing a semantic map. In previous research, RGB-D cameras have been utilized to obtain a semantic map. However, because of indoor objects and depth sensors, the accuracy and precision of the depth values could be improved, which is a key factor in reconstructing indoor scenarios. Moreover, there is a relationship between reflectivity and depth accuracy. Therefore, to obtain depth information that is better than that obtained in our previous research, we present a smart post rectification algorithm based on an artificial neural network (ANN). The algorithm improves the accuracy and precision of depth values by simultaneously considering reflectivity, distances, and different mechanisms of measuring depth. First, we analyze the RGB-D cameras' characteristics, including the pinhole camera model, lens distortions, and the types of error factors due to the types of RGB-D cameras used. Then, this paper proposes a smart post-rectification algorithm for depth images based on an ANN considering the depth error caused by reflectivity, the distance-related depth error, and different mechanisms for measuring depth. Finally, we perform experiments to evaluate the accuracy and precision of the proposed post-rectification approach by using different types of depth sensors. To evaluate the performance of our proposed algorithm, the proposed approach is applied to RGB-D SLAM, which is tested in different indoor environments. The experimental results show that applying our post-rectification algorithm to indoor scenario reconstruction can result in more accurate and more detailed 3-D reconstruction of objects than other state-of-the-art methods, highlighting the robustness and efficiency of our proposed algorithm.","Title: MagicVO: End-to-End Monocular Visual Odometry through Deep Bi-directional Recurrent Convolutional Neural Network.\nYear: 2018\n\nAbstract: This paper proposes a new framework to solve the problem of monocular visual odometry, called MagicVO . Based on Convolutional Neural Network (CNN) and Bi-directional LSTM (Bi-LSTM), MagicVO outputs a 6-DoF absolute-scale pose at each position of the camera with a sequence of continuous monocular images as input. It not only utilizes the outstanding performance of CNN in image feature processing to extract the rich features of image frames fully but also learns the geometric relationship from image sequences pre and post through Bi-LSTM to get a more accurate prediction. A pipeline of the MagicVO is shown in Fig. 1. The MagicVO system is end-to-end, and the results of experiments on the KITTI dataset and the ETH-asl cla dataset show that MagicVO has a better performance than traditional visual odometry (VO) systems in the accuracy of pose and the generalization ability.","Title: Detection and Discrimination Thresholds for Haptic Gratings on Electrostatic Tactile Displays.\nYear: 2019\n\nAbstract: Designing algorithms for rendering haptic texture on electrostatic tactile displays requires a quantitative understanding of human perception. In this paper, we report detection and discrimination thresholds for haptic gratings rendered on such displays based on the waveform and amplitude of the applied voltage. The haptic gratings consist of functions that describe the variation in voltage amplitude as a function of the position of finger on the display. Four types of virtual haptic gratings are considered in two experiments. In Experiment I, we estimate the absolute detection thresholds of haptic gratings for four different voltage amplitude functions, consisting of spatial waveforms with sinusoidal, square, triangle, or sawtooth shape. In Experiment II, we report discrimination thresholds for haptic gratings at five reference values of the voltage amplitude (80, 120, 160, 200, and 240 Vpp) for each of the voltage amplitude functions used in Experiment I. The results indicate that the detection thresholds for the four virtual haptic gratings are between 30 and 36 Vpp, and that the JND increases with the increase of voltage amplitudes. In addition, the JNDs of the four virtual gratings differ significantly, with the lowest and highest values being given by the triangle and sawtooth waveform, respectively.","Title: Outage Analysis of Multirelay Multiuser Hybrid Satellite-Terrestrial Millimeter-Wave Networks.\nYear: 2018\n\nAbstract: In this letter, we investigate the outage probability (OP) performance of a multirelay multiuser hybrid satellite-terrestrial relay network operating at millimeter wave (mmWave) bands. Considering the dominant fading factor of the mmWave band is rain attenuation, we combine the long-term rain attenuation model with the statistical channel model to describe the mmWave channel. Then we utilize expec...","Title: Performance Analysis of Uplink Uncoordinated Code-Domain NOMA for SINs\nYear: 2018\n\nAbstract: Space information networks (SINs) are regarded as an effective solution to enable a broadband access capability in a global coverage and cost-effective manner for massive machine type communications (mMTC). A collision often occurs when two or more user equipments (UEs) select the same pilot in mMTCs, and the received colliding signals are treated as interference. In this paper, we first analyze the problem of pilot collision for uplink mMTCs in SIN, then we investigate the performance of an uncoordinated code domain non-orthogonal multiple access (NOMA) protocol. Moreover, to recover the information in collisions, we adopt successive interference cancellation (SIC) and successive joint decoding (SJD) under a shadowed-Rician fading and path loss satellite-ground channel model, and derive the expressions of the outage probability and maximum system throughput for SIC and SJD, respectively. Numerical and simulation results validate our analytical results and show that the maximum system throughput of SJD is almost double that of SIC.","Title: The Effect of Applied Normal Force on the Electrovibration.\nYear: 2019\n\nAbstract: Electrovibration has become one of the promising approaches for adding tactile feedback on touchscreen. Previous studies revealed that the normal force applied on the touchscreen by the finger affects significantly the electrostatic force. It is obvious that the normal force affects the electrostatic force if it changes the contact area between the finger and the touchscreen. However, it is unclear whether the normal force affects the electrostatic force when the apparent contact area is constant. In this paper, we estimated the electrostatic force via measuring the tangential force of the finger sliding on a 3M touchscreen at different normal forces under the constant apparent contact area. We found that the electrostatic force increases significantly as the normal force increases from 0.5 to 4.5N. We explained the experimental results using the most recently proposed electrostatic force model, which considers the effect of air gap. We estimated the averaged air gap thickness using the electrostatic force model. The results showed that the relationship between the air gap thickness and the normal force follows a power function. Our experiment suggests that the normal force has a significant effect on the air gap thickness, thus require consideration in the design of tactile feedback.","Title: Power Allocation Optimization of Multibeam Satellites for Integrated Satellite-Terrestrial Networks\nYear: 2018\n\nAbstract: The increasing demand for high data rate services over the integrated satellite-terrestrial network has pushed for the development of millimeter-wave (mmWave) band high throughput satellites (HTS) with multibeams. However, existing multibeam HTS is with predetermined beam connection. Considering the mmWave channel is much more sensitive to the weather conditions than the conventional S/C/X band channels, it is important to allocate the limited transmission power to the beams that connect to the ground station in good state. Moreover, due to the huge distance and long propagation delay in the integrated satellite-terrestrial networks, the multibeam HTS can only obtain delayed Channel State Information (CSI) from feedback. In this paper, we model this problem as a Partially Observable Markov Decision Process (POMDP), and propose a power allocation optimization over two identical Gilbert-Elliott beams HTS communication, which can partly mitigate the negative effects of adverse weather conditions. The key thresholds for selecting the optimal power allocation method in the multibeam HTS communications are derived. The effectiveness and potentialities of our proposed scheme is verified through simulation results.","Title: Design and Analysis of NCed-HARQ Transmission Scheme for Space Information Networks\nYear: 2018\n\nAbstract: With the development of high throughput satellites and space information networks (SINs), broadband satellite communication networks is viewed as an important component to improve system coverage and throughput in the upcoming fifth generation (5G) networks. In this paper, we propose a network coded (NCed) hybrid automatic repeat request (HARQ) transmission scheme for the backbone high throughput satellites in SINs, in order to satisfy the ever-increasing broadband communication service demands. We first present our NCed-HARQ transmission scheme for multiple unicast flows in a practical SIN downlink scenario. Then the mean number of NCed-HARQ transmission rounds is derived. Moreover, a new representation and calculation method by using the Laplace transform for reliable data delivery in NCed-HARQ is also presented, where the derivation of throughput expressions is in a matrix exponential distribution form. Finally, we compare the throughput performance of our NCed-HARQ with NCed-ARQ scheme and HARQ transmission scheme. Simulation results show that our NCed-HARQ transmission scheme can enhance the throughput, especially in the high signal-to-noise region.","Title: An Efficient Construction Method for Ultra-Reliable Finite Length Analog Fountain Codes\nYear: 2018\n\nAbstract: Ultra-reliable low latency communication (URLLC) is defined by the the third generation partnership project (3GPP) for the fifth generation (5G) mobile systems. In order to realize the stringent requirements of ultra-high reliability and low latency, the data block length needs to be small. However, most of the state-of-art channel codes are designed and optimized for long block length. Analog fountain code (AFC) is a capacity-approaching self-adaptive code on wireless channels with linear encoding/decoding complexity. In this paper, we study the optimization of AFC in the finite length regime. We first analyze the effect of average degree on decoding performance of AFC in the finite length regime. Then, based on the characteristic of weight coefficient in AFC, we proposed a joint design of weight optimization (WO) progressive edge growth (PEG)-AFC algorithm to improve the decoding performance in the finite length regime, named PEG-AFC algorithm. Simulation results show that the proposed PEG-AFC algorithm can achieve lower bit error rate (BER) in a wide range of signal to noise ratio (SNR).","Title: Recurrent Binary Embedding for GPU-Enabled Exhaustive Retrieval from Billion-Scale Semantic Vectors.\nYear: 2018\n\nAbstract: Rapid advances in GPU hardware and multiple areas of Deep Learning open up a new opportunity for billion-scale information retrieval with exhaustive search. Building on top of the powerful concept of semantic learning, this paper proposes a Recurrent Binary Embedding (RBE) model that learns compact representations for real-time retrieval. The model has the unique ability to refine a base binary vector by progressively adding binary residual vectors to meet the desired accuracy. The refined vector enables efficient implementation of exhaustive similarity computation with bit-wise operations, followed by a near-lossless k-NN selection algorithm, also proposed in this paper. The proposed algorithms are integrated into an end-to-end multi-GPU system that retrieves thousands of top items from over a billion candidates in real-time. The RBE model and the retrieval system were evaluated with data from a major paid search engine. When measured against the state-of-the-art model for binary representation and the full precision model for semantic embedding, RBE significantly outperformed the former, and filled in over 80% of the AUC gap in-between. Experiments comparing with our production retrieval system also demonstrated superior performance. While the primary focus of this paper is to build RBE based on a particular class of semantic models, generalizing to other types is straightforward, as exemplified by two different models at the end of the paper.","Title: Efficient Design of Polar Coded STTD Systems over Rician MIMO Channels\nYear: 2017\n\nAbstract: In this paper, a polar coded space-time transmit diversity (STTD) scheme is proposed in order to improve the performance of MIMO system. In Rician fading MIMO channels, the corresponding polar coded STTD system can be equivalent to a single transmission channel for each polar code bit. Density evolutions for the polar coded STTD systems are proposed based on the analyses of the single transmission channel. The proposed density evolutions provide preferable guidance to construct polar codes for the polar coded STTD systems. Simulation results show that the BER performance of polar coded STTD system is significantly improved as the number of antennas increases. The proposed 2 x 2 polar coded STTD system can provide better FER performance than LDPC-based system under low and mid code rates.","Title: Optimal Transmission Policy Based on POMDP over Ka-Band Channels in SINs\nYear: 2017\n\nAbstract: The Ka-band channels can provide an appealing capacity for the future deep-space communications and space information networks (SINs). In this paper, the noise temperature of time-varying rain attenuation at Ka-band channels is modeled to two states Gilbert-Elliot channel, to capture the channel capacity that randomly ranging from good to bad state. An optimal transmission scheme based on Partially Observable Markov Decision Processes (POMDP) is proposed, and the key thresholds for selecting the optimal transmission method for space information networks (SIN) are derived. Simulation results show that our proposed scheme can effectively improve the throughput.","Title: Performance Analysis of MIMO-HARQ Schemes in LTP for Space Information Networks\nYear: 2017\n\nAbstract: Recently, with the development of Ka/Q/V mmWave band high throughput satellites (HTS) and space information networks (SIN), distributed/virtual multiple-input multiple-output (MIMO) over satellite have attracted considerable research interest. In this paper, we propose a novel performance analysis framework for MIMO with orthogonal space-time block coding (OSTBC) under Licklider transmission protocol (LTP) in upcoming SINs, that the closed-form expressions of the mean number of transmission rounds for reliable data delivery in automatic repeat request (ARQ) and hybrid-ARQ (HARQ) schemes is derived by using Laplace transform. Furthermore, we derive throughput expressions for lossless- and truncated-HARQ schemes, and investigate the data delivery delay in LTP over Rayleigh and Rician fading channels. We also verify the accuracy of our derived closed-form expressions of mean number of transmission rounds through the Monte Carlo simulations.","Title: Design of Rateless Transmission Scheme Based on Punctured Polar Codes\nYear: 2017\n\nAbstract: In this paper, a parallel concatenated punctured polar (PCPP) codes is designed to realise the rateless property of polar codes. First, an improved random puncturing pattern of polar codes is proposed to archive better performance than random puncturing. Then, the optimal initial code rate is analyzed for multiple PCPP code blocks transmission in slow fading channels, which the optimal initial code rate of each new PCPP code block is determined by the overhead of the previous successful decoded code block and each packet can be transmitted with encoding construct of a 2-level PCPP codes.","Title: Intermediate Performance of Rateless Codes over Dying Erasure Channel\nYear: 2017\n\nAbstract: In this paper, we propose a new rateless coding scheme for dying erasure channels with random channel lengths and time-varying packet error rates. Firstly, we propose a heuristic approach for suboptimal degree distributions based on AND-OR tree technique to achieve higher intermediate performance. Secondly, the optimal code length for the maximum average date delivery ratio is derived and analyzed. Simulation results demonstrate that our coding scheme outperforms existing conventional rateless codes with significantly better performance, which can be employed as a solution to the efficient large bulk transmission on dynamical and unreliable channels.","Title: Bounds on the Finite-Length RaptorQ Codes Under Maximum Likelihood Decoding\nYear: 2017\n\nAbstract: In this paper, we analysis the maximum likelihood (ML) decoding failure probability (DFP) of finite length RaptorQ codes with a high-order low density generator-matrix (LDGM) code as the pre-code. By investigating the rank of the product of two random coefficient matrices, we derive upper and lower bounds of DFP on the RaptorQ codes under ML decoding algorithm. Finally, we verify the accuracy of derived theoretical bounds through the Monte Carlo simulations with different degree distributions. The high accuracy bounds can be used to design near-optimum RaptorQ codes with short and moderate lengths.","Title: Outage Performance of Cooperative Deep-Space Downlink with Backbone Relaying in SBINs\nYear: 2017\n\nAbstract: In this paper, we investigate the performance of cooperative deep-space downlink with an amplify-and-forward (AF) backbone relaying in Space-based Information Networks (SBINs). In this SBINs communication scenario, we assume both the source-destination and relay-destination links undergo the shadowed-Rician fading, and the source-relay link follows the Rician fading distributions, respectively. Moreover, the effect of satellite perturbation of backbone relaying satellite is considered, and the maximum ratio combining is implemented at the terrestrial destination. Based on this setup, we first derive the approximate statistical distributions of signal-to-noise ratio of the system, then the closed-form expressions are obtained to efficiently evaluate the outage probability (OP) of the system. Finally, some simulation results are provided to verify our analysis.","Title: Rateless Coding Scheme Based on Autoregressive-Moving-Average Model over Ka-Band Links\nYear: 2017\n\nAbstract: Future deep space explorations and spatial information networks (SINs) are with the increasing demands for high data rate services, the application of Ka-band channel is viewed as a primary solution. However, the Ka-band channel is much more sensitive to the weather conditions than S/C/X-band channels. In this paper, the noise temperature on Ka-band channel is modeled as N-states Markov channel, and a practical time-varying rain attenuation prediction model is proposed based on the Autoregressive-Moving-Average (ARMA) model. By considering the tradeoffs between transmission latency, reliability and power allocations consumptions, we design an adaptive rateless coding scheme based on the analog fountain codes. Simulation results show that our proposed scheme can effectively improve the throughput and efficiency.","Title: Learning to Match Using Siamese Network for Object Tracking.\nYear: 2018\n\nAbstract: The general object tracking problem traditionally been tackled by modeling the object's appearance. In this paper we consider object tracking as a similarity measurement problem. We focus on learning a matching mechanism with great generalization ability. We present a Siamese convolutional neural network as a matching function to perform object tracking. First we simply match the exemplary target in previous frame with the candidates in a new frame using cosine similarity and return the most similar one by the learnt matching function. Then we perform bounding box regression to refine the target position given by the network as the final result. Extensive experiments on real-world benchmark datasets validate the superior performance of our approach.","Title: XML-based modeling method of phased-mission systems subject to probabilistic common cause failures.\nYear: 2019\n\nAbstract: With the increasing of system scale and the growing of functional requirements and interactions within and/or among system hierarchies, there are more difficulties for safety engineers to carry out their works. Especially, the research on phased mission system (PMS) with probabilistic common cause failures (PCCFs) is still in the initial stage and has a lot of limitations, because the current researches have not yet considered the dynamic characteristics of PMSs. In this paper, a modular method is proposed as the theoretical basis to construct the components model in the PMS with PCCF. The relationships between common cause events were discussed and the probabilistic model of CCFs is extended, so that the model can fit for different statistical relations, and a module-based modeling and analysis method using binary decision diagram (BDD) and Markov model were proposed to deal with static and dynamic module in PMS respectively. Moreover, a standardization of description method for modular method using extensible markup language (XML) is given, based on which the system reliability model can be constructed by computer aided. Finally, the proposed method is demonstrated through a case study.","Title: A Three-Hierarchy Evaluation of Polarimetric Performance of GF-3, Compared with ALOS-2/PALSAR-2 and RADARSAT-2.\nYear: 2019\n\nAbstract: GaoFen-3 (GF-3) is the first Chinese civilian multi-polarization synthetic aperture radar (SAR) satellite, launched on 10 August of 2016, and put into operation at the end of January 2017. The polarimetric SAR (PolSAR) system of GF-3 is able to provide quad-polarization (quad-pol) images in a variety of geophysical research and applications. However, this ability increases the complexity of maintaining image quality and calibration. As a result, to evaluate the quality of polarimetric data, polarimetric signatures are necessary to guarantee accuracy. Compared with some other operational space-borne PolSAR systems, such as ALOS-2/PALSAR-2 (ALOS-2) and RADARSAT-2, GF-3 has less reported calibration and image quality files, forcing users to validate the quality of polarimetric imagery of GF-3 before quantitative applications. In this study, without the validation data obtained from a calibration infrastructure, an innovative, three-hierarchy strategy was proposed to assess PolSAR data quality, in which the performance of GF-3 data was evaluated with ALOS-2 and RADARSAT-2 data as references. Experimental results suggested that: (1) PolSAR data of GF-3 satisfied backscatter reciprocity, similar with that of RADARSAT-2; (2) most of the GF-3 PolSAR images had no signs of polarimetric distortion affecting decomposition, and the system of GF-3 may have been improved around May 2017; and (3) the classification accuracy of GF-3 varied from 75.0% to 91.4% because of changing image-acquiring situations. In conclusion, the proposed three-hierarchy approach has the ability to evaluate polarimetric performance. It proved that the residual polarimetric distortion of calibrated GF-3 PolSAR data remained at an insignificant level, with reference to that of ALOS-2 and RADARSAT-2, and imposed no significant impact on the polarimetric decomposition components and classification accuracy.","Title: ARM: Adaptive Random-Selected Multi-Beamforming Estimation Scheme for Satellite-Based Internet of Things.\nYear: 2019\n\nAbstract: In this paper, we focus on the millimeter-wave (mmWave) band multiple-input and multiple-output (MIMO) channel estimation in the satellite-based Internet of Things (S-IoT). At first, we establish a sparse geometric-based mmWave MIMO channel model between a high throughput satellite (HTS) and multiple terrestrial user equipments (UEs) for the S-IoT downlink system. By exploiting the sparsity inherent to themmWave band channel, we propose an efficient adaptive random-selected multi-beamforming (ARM) estimation scheme, which can simultaneously estimate themmWave MIMO channel state information (CSI) for multiple UEs in angle domain. The ARM estimation scheme measures of the CSI between the HTS and multiple UEs by utilizing a series of random combinations of transmitting beamforming vectors and receiving UEs' antennas and the required number of measurements can adaptively reduce as well as the signal-to-noise ratios (SNR) increases. To further improve the performance of ARM estimation scheme, the number of each beamforming been selected for the channel measurement is buffered, and modify the probability of the random selection of beams and UEs. Two improved ARM estimation schemes are proposed, one is ARM forcing adaptation beam selection (ARM-FABS) scheme, and the other is ARM partially estimated beam selection (ARM-PEBS) scheme. The simulation results show that the proposed ARM estimation schemes can reduce the required number of measurements and achieve a better tracking performance over a wide range of SNRs.","Title: Deep Learning-Based Long-Term Power Allocation Scheme for NOMA Downlink System in S-IoT.\nYear: 2019\n\nAbstract: In this paper, we formulate a long-term resource allocation problem of non-orthogonal multiple access (NOMA) downlink system for the satellite-based Internet of Things (S-IoT) to achieve the optimal decoding order and power allocation. This long-term resource allocation problem of the satellite NOMA downlink system can be decomposed into two subproblems, i.e., a rate control subproblem and a power allocation subproblem. The latter is a non-convex problem and the solution of which relies on both queue state and channel state. However, the queue state and the channel state continually change from one time slot to another, which makes it extremely strenuous to characterize the optimal decoding order of successive interference cancellation (SIC). Therefore, we explore the weight relationship between the queue state and the channel state to derive an optimal decoding order by leveraging deep learning. The proposed deep learning-based long-term power allocation (DL-PA) scheme can efficiently derive a more accurate decoding order than the conventional solution. The simulation results show that the DL-PA scheme can improve the performance of the S-IoT NOMA downlink system, in terms of long-term network utility, average arriving rate, and queuing delay.","Title: Joint Power Allocation and Rate Control for NOMA-based Space Information Networks\nYear: 2019\n\nAbstract: In this paper, we propose a novel power allocation scheme of downlink non-orthogonal multiple access (NOMA) system for space information networks (SINS). Since the communication resources such as power and storage on satellites are limited, we focus on an optimization policy of long-term resource allocation to meet these practical constraints. To address this problem, we convert the long-term optimization problem into a series of online power allocation and rate control problems by leveraging the Lyapunov optimization framework. Then, we employ the particle swarm optimization (PSO) algorithm to derive a globally optimal solution for this joint optimization problem, with a linear computational complexity. Simulation results show that the proposed joint optimization allocation NOMA scheme for SIN can outperform OMA and multiple sub-optimal NOMA benchmark schemes, in terms of long-term network utility, average arriving rate and queuing delay.","Title: Optimized Puncturing for the Spinal Codes\nYear: 2019\n\nAbstract: As a type of newly invented rateless codes, Spinal codes can achieve the capacity of both additive white Gaussian noise (AWGN) channel and binary symmetric channel (BSC) with short message length and pseudo-random like codewords. In this paper, a novel puncturing pattern called inverted triangle-shaped puncturing is proposed for Spinal codes. We prove a lemma as theoretical support for the proposed inverted triangle-shaped puncturing. Compared with the uniform puncturing pattern, Spinal codes can be punctured to achieve both high and finer-grained rates by the inverted triangle-shaped puncturing, without increasing the cost of decoding. Extensive simulations are carried out to verify the effectiveness of the proposed pattern. Results show that the inverted triangle-shaped puncturing pattern can increase the code rate significantly without any harming to the bit error rate (BER) performance.","Title: GalaXC: Graph Neural Networks with Labelwise Attention for Extreme Classification\nYear: 2021\n\nAbstract: ABSTRACT This paper develops the GalaXC algorithm for Extreme Classification, where the task is to annotate a document with the most relevant subset of labels from an extremely large label set. Extreme classification has been successfully applied to several real world web-scale applications such as web search, product recommendation, query rewriting, etc. GalaXC identifies two critical deficiencies in leading extreme classification algorithms. First, existing approaches generally assume that documents and labels reside in disjoint sets, even though in several applications, labels and documents cohabit the same space. Second, several approaches, albeit scalable, do not utilize various forms of metadata offered by applications, such as label text and label correlations. To remedy these, GalaXC presents a framework that enables collaborative learning over joint document-label graphs at massive scales, in a way that naturally allows various auxiliary sources of information, including label metadata, to be incorporated. GalaXC also introduces a novel label-wise attention mechanism to meld high-capacity extreme classifiers with its framework. An efficient end-to-end implementation of GalaXC is presented that could be trained on a dataset with 50M labels and 97M training documents in less than 100 hours on 4 × V100 GPUs. This allowed GalaXC to not only scale to applications with several millions of labels, but also be up to 18% more accurate than leading deep extreme classifiers, while being upto 2-50 × faster to train and 10 × faster to predict on benchmark datasets. GalaXC is particularly well-suited to warm-start scenarios where predictions need to be made on data points with partially revealed label sets, and was found to be up to 25% more accurate than extreme classification algorithms specifically designed for warm start settings. In A/B tests conducted on the Bing search engine, GalaXC could improve the Click Yield (CY) and coverage by 1.52% and 1.11% respectively. Code for GalaXC is available at https://github.com/Extreme-classification/GalaXC","Title: An Adaptive Decomposition Approach With Dipole Aggregation Model For Polarimetric Sar Data\nYear: 2021\n\nAbstract: Polarimetric synthetic aperture radar (PolSAR) has attracted lots of attention from remote sensing scientists because of its various advantages, e.g., all-weather, all-time, penetrating capability, and multi-polarimetry. The three-component scattering model proposed by Freeman and Durden (FDD) has bridged the data and observed target with physical scattering model, whose simplicity and practicality have advanced remote sensing applications. However, the three-component scattering model also has some disadvantages, such as negative powers and a scattering model unfitted to observed target, which can be improved by adaptive methods. In this paper, we propose a novel adaptive decomposition approach in which we established a dipole aggregation model to fit every pixel in PolSAR image to an independent volume scattering mechanism, resulting in a reduction of negative powers and an improved adaptive capability of decomposition models. Compared with existing adaptive methods, the proposed approach is fast because it does not utilize any time-consuming algorithm of iterative optimization, is simple because it does not complicate the original three-component scattering model, and is clear for each model being fitted to explicit physical meaning, i.e., the determined adaptive parameter responds to the scattering mechanism of observed target. The simulation results indicated that this novel approach reduced the possibility of the occurrence of negative powers. The experiments on ALOS-2 and RADARSAT-2 PolSAR images showed that the increasing of adaptive parameter reflected more effective scatterers aggregating at the 45 degrees direction corresponding to high cross-polarized property, which always appeared in the 45 degrees oriented buildings. Moreover, the random volume scattering model used in the FDD could be expressed by the novel dipole aggregation model with an adaptive parameter equal to one that always appeared in the forest area.","Title: Age-optimal Transmission Policy for Intelligent HARQ-CC aided NOMA Systems\nYear: 2021\n\nAbstract: This paper investigates the timeliness performance of a downlink wireless communication system with a base station (BS) serving two users under the non-orthogonal multiple access (NOMA) system. The hybrid automatic repeat request with chase combining (HARQ-CC) in finite blocklength is considered. For minimizing the information freshness which is characterized by Age of Information (AoI), an intelligent system is adopted. The BS can adjust the power allocation to each user in NOMA, and decide to transmit old or new packets to each user, according to the users' current AoI status and the positive/negative acknowledgement (ACK/NACK) feedback signal. First, the closed-form of the individual user's outage probability with arbitrary power allocation combination of HARQ-CC aided NOMA system is derived. Based on the outage probability, the optimization of the system average AoI is achieved by minimizing the Lyapunov Drift function of each time slot. By introducing the HARQ-CC mechanism into the NOMA scheme, a trade-off between reliability and timeliness can be achieved, which is found that this policy can improve the AoI performance of NOMA scheme in low signal-noise ratio (SNR) and outperform existing works on NOMA and orthogonal multiple access (OMA).","Title: Age-optimal Power Allocation Policies for NOMA and Hybrid NOMA/OMA Systems\nYear: 2021\n\nAbstract: In this paper, we study downlink short-packet communication in wireless networks, where a base station (BS) sends time-sensitive status updates to users via non-orthogonal multiple access (NOMA) or Adaptive NOMA/orthogonal multiple access (OMA). The Age of Information (AoI), namely the amount of time that elapsed since the most recently delivered packet was generated, captures the freshness of the information. We aim to minimize the Expected Weighted Sum AoI (EWSAoI) by optimizing the power allocation. First, a low-complexity power allocation policy, namely Stationary Power Allocation policy is proposed in NOMA. In this policy, the BS allocates fixed power to each user and we obtain the closed-form expression of the optimal allocation factor to minimize the EWSAoI. Then, we propose an Adaptive NOMA/OMA policy based on Lyapunov Optimization in which the BS can adaptively switch between NOMA and OMA and dynamically allocate power for users to keep the EWSAoI low. Numerical results demonstrate the advantages of the proposed policies, which provide useful insights for practical system designs.","Title: Age-Optimal Power Allocation Scheme for NOMA-based S-IoT Downlink Network\nYear: 2021\n\nAbstract: In this paper, we consider a non-orthogonal multiple access (NOMA)-based satellite-integrated internet of things (S-IoT) network, where a satellite transmits timely status updates to multiple user equipments (UEs). To keep the freshness of status updates in this network, we formulate an age of information (AoI) optimization problem subject to long/short-term power and throughput constraints. We leverage tools from Lyapunov optimization to transform the optimization problem into a sequence of online power allocation problems. Since the original optimization problem is non-convex and hard to find the optimal solution, we utilize the particle swarm optimization (PSO) algorithm to obtain an optimal solution within a linear computational complexity. Simulation results show that our proposed NOMA-AoI scheme outperforms the benchmark schemes with regard to AoI performance. Furthermore, we also discuss the impact of importance weight V on the AoI and power consumption and validate the tradeoff.","Title: Efficient Ordered Statistics Decoder for Ultra-Reliable Low Latency Communications\nYear: 2021\n\nAbstract: Short length channel coding and low complexity decoding is essential for 5G ultra-reliable low latency communications (uRLLC). In this paper, au efficient ordered statistics decoder (E-OSD) scheme is proposed for finite length non-binary Raptor code (NBRC) towards uRLLC. The segmentation and discarding rules of test error patterns, and the stop criteria are designed for the proposed E-OSD scheme to reduce the decoding complexity. A block error rate (BLER) upper bound of the NBRC under OSD is derived to estimate the number of NBRC symbols required for achieving the desired BLER performance. Simulation results show that the complexity of the proposed E-OSD scheme is greatly reduced compared to the existing OSD schemes, and it can achieve the BLER lower than 10(-5) in the finite length regime (<256 bits), satisfying the requirements of uRLLC.","Title: Random Access with and without Sensing in Non-Terrestrial Networks for Timely Updates\nYear: 2021\n\nAbstract: The growing boom in time-critical applications such as remote sensing and monitoring has made low latency of information an important requirement. Age of information (AoI) has been proposed to measure the freshness of information from the receiver side. In this paper, we analyze that multiple sources transmit their status packets to a remote controller for timely updates. Characterized by long transmission distances, satellite networks are commonly using Aloha as a random access protocol by preconceiving channel sensing is low efficient. Yet, for some non-terrestrial networks where the propagation delay is comparable to the transmission time, the performance comparison between Aloha and CSMA requires more detailed consideration. By building the node-centric discrete-time Markov chain, we quantify the performance of Aloha and CSMA on AoI and give the performance break-even point. Only when the ratio of propagation delay to transmission time is larger than this point, Aloha performs better on the timeliness metric. Furthermore, we derive the optimal attempt probability of CSMA to achieve the lowest latency. In the end, simulation results confirmed the validity of the theoretical analysis.","Title: Scheduling Strategy Design Framework For Cyber-Physical System With Non-Negligible Propagation Delay\nYear: 2021\n\nAbstract: Cyber-physical systems (CPS) have been widely employed as wireless control networks. There is a special type of CPS which is developed from the wireless networked control systems (WNCS). They usually include two communication links: Uplink transmission and downlink transmission. Those two links form a closed-loop. When such CPS are deployed for time-sensitive applications such as remote control, the uplink and downlink propagation delay are non-negligible. However, existing studies on CPS/WNCS usually ignore the propagation delay of the uplink and downlink channels. In order to achieve the best balance between uplink and downlink transmissions under such circumstances, we propose a heuristic framework to obtain the optimal scheduling strategy that can minimize the long-term average control cost. We model the optimization problem as a Markov decision process (MDP), and then give the sufficient conditions for the existence of the optimal scheduling strategy. We propose the semi-predictive framework to eliminate the impact of the coupling characteristic between the uplink and downlink data packets. Then we obtain the lookup table-based optimal offline strategy and the neural network-based suboptimal online strategy. Numerical simulation shows that the scheduling strategies obtained by this framework can bring significant performance improvements over the existing strategies.","Title: MSPA: Multislot Pilot Allocation Random Access Protocol for mMTC-Enabled IoT System\nYear: 2021\n\nAbstract: To provide massive connectivity in massive machine-type communications (mMTCs) for the Internet of Things (IoT) system, a novel grant free random access protocol, called multislot pilot allocation (MSPA) is proposed in this article, where the user equipments (UEs) are permitted to jointly transmit randomly chosen pilot sequences along with their data packets over multislot to resolve intracell pil...","Title: An Age Optimized Hybrid ARQ Scheme for Polar Codes via Gaussian Approximation\nYear: 2021\n\nAbstract: In this letter, we take the lead in investigating the average AoI performance for polar coded status updates over the additive white Gaussian noise (AWGN) channels. Compared with the non-automatic repeat request (non-ARQ) scheme, the hybrid ARQ with chase combining (HARQ-CC) scheme can effectively reduce the average AoI, especially in the low signal-to-noise ratio (SNR) region. Then, to improve th...","Title: Taming Sparsely Activated Transformer with Stochastic Experts.\nYear: 2022\n\nAbstract: Sparsely activated models (SAMs), such as Mixture-of-Experts (MoE), can easily scale to have outrageously large amounts of parameters without significant increase in computational cost. However, SAMs are reported to be parameter inefficient such that larger models do not always lead to better performance. While most on-going research focuses on improving SAMs models by exploring methods of routing inputs to experts, our analysis reveals that such research might not lead to the solution we expect, i.e., the commonly-used routing methods based on gating mechanisms do not work better than randomly routing inputs to experts. In this paper, we propose a new expert-based model, THOR (Transformer witH StOchastic ExpeRts). Unlike classic expert-based models, such as the Switch Transformer, experts in THOR are randomly activated for each input during training and inference. THOR models are trained using a consistency regularized loss, where experts learn not only from training data but also from other experts as teachers, such that all the experts make consistent predictions. We validate the effectiveness of THOR on machine translation tasks. Results show that THOR models are more parameter efficient in that they significantly outperform the Transformer and MoE models across various settings. For example, in multilingual translation, THOR outperforms the Switch Transformer by 2 BLEU scores, and obtains the same BLEU score as that of a state-of-the-art MoE model that is 18 times larger. Our code is publicly available at: github.com/microsoft/Stochastic-Mixture-of-Experts.","Title: Massive Access in Space-Based Internet of Things: Challenges, Opportunities, and Future Directions\nYear: 2021\n\nAbstract: The integration of fifth generation (5G) mobile network and satellite communication promises a promotion on the interconnection of everything, and has become one of the key development directions of beyond 5G and even 6G. As an inevitable development trend of mobile communication, the space-based Internet of Things (S-IoT) is expected to be commercially available in building an integrated informat...","Title: Adjustable Ordered Statistic Decoder for Short Block Length Code towards URLLC\nYear: 2021\n\nAbstract: The fifth generation (5G) ultra-reliable low latency communications (uRLLC) needs short block length codes to ensure the low latency requirement, which also brings the challenge in the design of maximum likelihood decoder (MLD) with practical complexity. In this paper, an adjustable-ordered statistics decoder (OSD) algorithm is proposed for short block length code to achieve the MLD performance wi...","Title: Spinal Codes Over Fading Channel: Error Probability Analysis and Encoding Structure Improvement\nYear: 2021\n\nAbstract: In order to facilitate the reliability of data transmission of Spinal codes over the fading channel, performance analysis of Spinal codes is conducted, and an improved encoding structure is proposed. First, we derive an approximate frame error rate (FER) upper bound for Spinal codes over the Rayleigh fading channel in the finite block length (FBL) regime. Then, inspired by the FER analysis process...","Title: Freshness-Critical Transmission Scheme with IR-HARQ over Multi-Hop Satellite-IoT\nYear: 2021\n\nAbstract: With the development of low earth orbits (LEO) high throughput satellite (HTS), satellite-Internet of Things (S-IoT) has become a crucial direction in beyond 5G (B5G) and future sixth generation (6G) mobile system due to the ubiquitous coverage and broadband access capability inherited from the HTS. Several S-IoT applications for monitoring status updates can be seen as classic cases of real time transmission, where the main performance parameters are the information freshness and fairness of the network, i.e., the age of information (AoI) and Jain's Fairness Index (JFI), respectively. In this paper, we propose a freshness-critical incremental-redundancy hybrid automatic repeat request (FCIR-HARQ) multi-hop transmission scheme to improve the AoI and JFI performance, where each hop adopts the Last Come First Serve with preemption only in waiting (LCFS-W) policy with a buffer only store the latest file. In particular, we derive the closed form expression of average AoI (AAoI) in the above multi-hop S-IoT, and analyze the corresponding JFI in each hop. Simulation results validate the accuracy of our derivations, and show that the proposed FCIR-HARQ multi-hop transmission scheme with LCFS- W policy outperforms the existing First Come First Serve (FCFS) policy in terms of AAoI.","Title: Age-Critical Blockchain Resource Allocation over Satellite-based Internet of Things\nYear: 2021\n\nAbstract: With the development of next generation of mobile communications, the access of massive Internet of Things (IoT) devices need a more intelligent and secure network. Blockchain has become an emerging technology due to its characteristics of decentralization, stability and transparency. Thus, the combination of blockchain and IoT has attracted the focus of researches. However, the conventional blockchain based on terrestrial network are limited to the scalability and latency. With the support of the wide coverage of satellite, satellite-based Internet of Things (S-IoT) can solve the defect of large consensus latency of blockchain in terrestrial networks. In this paper, considering the limitation of system power and to improve the freshness of information, i.e., the age of information (AoI), we propose a power allocation scheme to accelerate the blockchain consensus over the S-IoT network. Then, we derive the closed-form expressions to the latency and power consumption of blockchain consensus over the S-IoT network. Moreover, we formulate an average AoI (AAoI) optimization problem subject to the total power constraints and solve it by genetic algorithm. Simulation results show that the proposed power allocation scheme has a superior performance in terms of AAoI and throughput compared to the conventional blockchain schemes.","Title: Age-Critical Frameless ALOHA Protocol for Grant-Free Massive Access\nYear: 2021\n\nAbstract: In this paper, we analyze the freshness of information in grant-free massive access via a new metrics named age of information (AoI), and propose an age-critical frameless ALOHA (ACFA) random access protocol, where the average AoI (AAoI) is implicitly reduced by banning the transmission of activated user equipments (UEs) recovery successful in the last frame. In particular, in order to analyze the AAoI performance of the ACFA random access protocol, we define two metrics named the average channel load and packets recovery rate (PRR) of ACFA protocol, and tracking the evolution of the number of access-allowed UEs in each frame. Then we derive an analytical expression of AAoI as a function of the frame length and the PRR in the ACFA random access protocol. Simulation results validate the accuracy of our theoretical analysis and show the great potential of ACFA random access protocol in minimizing AAoI.","Title: Age-Critical Pilot Allocation Random Access Protocol for Space-Air-Ground Integrated Networks\nYear: 2021\n\nAbstract: Due to ubiquitous coverage inherited from the satellites, space-air-ground integrated networks (SAGIN) has been viewed as a promising enabler to provide \"anywhere and anytime\" broadband access for the next generation of mobile network. Nevertheless, the status updating to the satellite of terrestrial sensing devices could be hindered by the propagation delay. As a result, it becomes crucial to investigate the timeliness of information for massive machine type communications (mMTC) random access in SAGIN. In this paper, we analyse the timeliness of information for the mMTC random access scenario via a new performance metric named age of information (AoI), and propose an age-critical pilot allocation (ACPA) random access protocol aiming to lower the system average Aol (AAoI). By tracking the Aol evolution of each device via Markovian analysis, the closed-form expression of the system AAoI is derived, then we conduct an optimal number of slots to achieve the lowest system AAoI with the increasing of the system load. Simulation results validate the accuracy of our theoretical analysis, and also show that our ACPA protocol can significantly outperform other relevant random access protocols in terms of reducing the AAoI in overload cases.","Title: Self-Adaptive Ordered Statistics Decoder for Finite Block Length Raptor Codes Toward URLLC\nYear: 2022\n\nAbstract: Rateless codes can adapt to the wireless channel conditions without accurate channel state information (CSI) at the transmitter side, avoiding CSI feedback and retransmission, and thus are a promising channel coding approach to meet the stringent requirements of ultrareliable low-latency communications (uRLLCs). This article investigates a self-adaptive ordered statistics decoder (S-OSD) scheme fo...","Title: CS-LTP-Spinal: a cross-layer optimized rate-adaptive image transmission system for deep-space exploration\nYear: 2022\n\nAbstract: Reliable and efficient image transmission is crucial for deep-space exploration. However, the extremely long distance and complex deep-space environment introduce severe design and implementation challenges. In this work, we propose a novel high-efficiency system, CS-LTP-Spinal, to address the challenges encountered in deep-space image transmission. CS-LTP-Spinal is designed to work over the Licklider transmission protocol (LTP) of the delay-tolerant network (DTN). By incorporating compressed sensing (CS) and the Spinal codes as the application and physical layer techniques, CS-LTP-Spinal can satisfy the constraints originating from resource asymmetry between the space vehicles and the ground station. To match the time-varying deep-space channels, two coarse-grained rate-adaptive transmission strategies are designed that employ different CS decompression mechanisms based on erasure-tolerant and error-tolerant decompression, respectively, to exploit the robustness of CS reconstruction to erasures and errors. Then, the rates of CS compression and Spinal coding are optimized over the application, transport, and physical layers. A semi-physical deep-space communication platform is built, and extensive simulations on the Mars-to-Earth scenario are conducted. The results demonstrate that the designed CS-LTP-Spinal system with cross-layer optimized rate-adaptive transmission strategies has significant performance advantages over its counterparts by achieving near-ideal image transmission efficiency.","Title: Real-Time Aeromagnetic Compensation With Compressed and Accelerated Neural Networks\nYear: 2022\n\nAbstract: As neural networks become an increasingly popular technique in the field of aeromagnetic compensation, there is an increasing demand for hardware systems with more computing power. Compared with the linear regression method, applying a neural network to the task of real-time compensation is difficult because of insufficient computing resources in the unmanned aerial vehicle (UAV) flight detection platform. To perform real-time compensation calculations with limited computing resources, we optimized back propagation neural network (OBPNN) through model compression and acceleration. In this study, we found that the most time-consuming part of network training is the iterative updating of the weights in the BPNN interference model. Using transfer learning, we replace the randomly initialized weights (RWs) with pretrained weights, thereby greatly reducing the number of iterations required. We also apply other model compression and acceleration algorithms. In a case study of our new technique, we implement the fast training of the OBPNN on a Raspberry Pi 4B system. This network processes approximately 316 samples per 0.1 s, which is fast enough to complete aeromagnetic compensation in real time.","Title: On the Prediction Policy for Timely Status Updates in Space-Air-Ground Integrated Transportation Systems\nYear: 2022\n\nAbstract: In this paper, we investigate the timeliness of the vehicular status updates in space-air-ground integrated networks (SAGIN) for intelligent transportation systems (ITS). The Age of Information (AoI) is introduced to capture the timeliness of the vehicular status updates. To overcome the inherent end-to-end latency taken by the long-distance communications in SAGIN for ITS, prediction has attracte...","Title: Tradeoff Optimization Technology of Effectiveness-Cost for Satellite-Based on CAIV Method\nYear: 2022\n\nAbstract: The tradeoff of effectiveness and cost is a vital problem for complex industrial systems, mainly applied in the weapons and aviation fields. As a typical complex industrial system, the effectiveness-cost tradeoff of the satellites becomes challenging and interesting. This paper takes a remote sensing satellite as a research object, and an integrated approach to assess and optimize its effectiveness and cost is proposed. The characteristic parameters are selected according to an analysis of its structure and mission. Furthermore, the effectiveness evaluation model is established based on the Availability-Dependability-Capability (ADC) model, and the cost parameter model is developed using historical data and regression analysis. According to the Cost as Independent Variable (CAIV) method, the objective function of the satellite effectiveness-cost with the effectiveness-cost tradeoff space is established. The objective function is solved and optimized using a genetic algorithm to achieve a more efficient and economical satellite design scheme.","Title: Grant Free Age-Optimal Random Access Protocol for Satellite-Based Internet of Things\nYear: 2022\n\nAbstract: In satellite-based Internet of Things (S-IoT) system, the timely status updating of terrestrial sensing user equipments (UEs) to satellite could be hampered by the long propagation delay, especially in massive machine type communications (mMTC). To guarantee the information freshness in S-IoT, a new performance indicator called age of information (AoI) is exploited to analyze the average AoI (AAoI) in the overload case of mMTC, and a grant free age-optimal (GFAO) random access protocol is proposed to lower the AAoI. Specifically, the closed-form expression of AAoI is derived by tracing the instantaneous AoI evolution of each UE through Markov analysis. Then, the proposed GFAO random access protocol is proved to achieve a minimum AAoI and a maximum throughput in S-IoT, by adjusting the number of access time slots in each transmission frame in the overload case of mMTC. Extensive simulations are conducted to validate the theoretical analysis, and show that there exists different optimal value of access time slots in system load region from 0.2 to 3, which can minimize AAoI and maximize throughput in the proposed GFAO random access protocol.","Title: On Scheduling Policy for Multi-process Cyber-Physical System with Edge Computing\nYear: 2022\n\nAbstract: In this paper, we consider a cyber-physical system (CPS) with multiple Internet of Things (IoT) devices. There are multiple independent linear time-invariant processes in the system, which are sampled by sensors, scheduled by controllers and controlled by actuators. In the literature of wireless control CPS, commonly assume that the system just have one controller and ignore the processing time on server. In this work we employ the edge computing, the controllers are facilitated by edge server and cloud server. The processing time of status update depends on the characteristic of different processes and servers. By taking into account such conditions, we mainly investigate how to choose the destination of status updates (i.e., edge server or cloud server) to minimize the average Mean Square Error (MSE) of the entire system. To address this issue, we formulate a Markov Decision Process (MDP) problem and obtain the optimal scheduling policy. The threshold property of the optimal scheduling policy is proved, and a suboptimal policy is proposed to overcome the curse of dimensionality. The simulation results illustrate that the selection of controller is related to the timeliness of process and show the superiority of the proposed policies.","Title: Partial Self-Concatenation Structure and Performance Analysis of Spinal Codes Over Rayleigh Fading Channel\nYear: 2022\n\nAbstract: Spinal codes are a new family of rateless codes which have been proved to be capacity-achieving over both the additive white Gaussian noise (AWGN) channel and the binary symmetric channel (BSC). However, over the Rayleigh fading channel between the vehicle nodes, the error performance of Spinal codes is not satisfactory since the tail message blocks of Spinal codes are prone to error. To solve this issue, this paper proposes a new practical partial self-concatenation coding structure of Spinal codes, named \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$N$</tex-math></inline-formula>\n tail-protected Spinal codes, to pointedly protect tail message blocks of Spinal codes over the flat Rayleigh fading channel. Theoretical performance analysis and simulation results are also provided to validate and verify the effectiveness of the proposed \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$N$</tex-math></inline-formula>\n tail-protected Spinal codes.","Title: Short Analog Fountain Code With Quasi-Gray Constellation Mapping Modulation Towards uRLLC\nYear: 2022\n\nAbstract: In this paper, a capacity-approaching rateless coded modulation towards ultra-reliable low latency communications (uRLLC) is proposed, including the joint design of short block-length analog fountain code (AFC) and quasi-gray constellation mapping (QGCM) modulation at the transmitter, and a limited feedback mechanism for the receiver. First, based on the nonlinear constellation and quasi-gray mapping, we design a novel rateless coded modulation scheme called AFC-QGCM, and prove it can approach to the Shannon capacity. Further, the theoretical evaluation framework of information density between the achievable rate and signal-to-noise (SNR) of the AFC-QGCM schemes is derived under short block-length. Based on the analysis, we propose a rateless transmission scheme with a limited feedback link over the fading channel without precise channel state information (CSI) at the transmitter, which could utilize the theoretical analysis to determine the optimal coding and modulation parameters during the transmission. Both analysis and simulation results shown that the proposed scheme could approaching to the Polyanskiy-Poor-Verdu (PPV) meta converse benchmark in a wide range SNRs.","Title: Age-Oriented Transmission Protocol Design in Space-Air-Ground Integrated Networks\nYear: 2022\n\nAbstract: In this paper, we study the age-oriented hybrid automatic repeat request (HARQ) protocol design in space-air-ground integrated networks (SAGINs) scenarios. A real-time communication system, where the updates are delivered from the remote nodes to terrestrial devices, is formulated. As the end-to-end latency \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$D$ </tex-math></inline-formula>\n is nontrivial, the traditional HARQ with frequent feedbacks is not always beneficial to timely transmission. Intuitively, there is a threshold \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$D^{*}$ </tex-math></inline-formula>\n of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$D$ </tex-math></inline-formula>\n, only within which retransmission is advantageous to age. Inspired by this, we formulate an age-optimal redundancy allocation problem and derive the explicit expression of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$D^{*}$ </tex-math></inline-formula>\n for advantageous retransmissions. Besides, to further increase the timeliness of the system, we propose a fast incremental redundancy hybrid ARQ protocol (fast IR-HARQ), where successive decoding and feedback operations are omitted based on channel estimation. Considering the shadowed Rician fading channel and finite blocklength regime, we derive expressions of the average age for the standard IR-HARQ and fast IR-HARQ setups. As expected, the proposed fast IR-HARQ scheme reduces the average age significantly compared with the IR-HARQ strategy. Further, we evaluate the influence of different parameters on the age performance of the fast IR-HARQ scheme. The results demonstrate the superiority of the proposed fast IR-HARQ protocol without loss of reliability.","Title: A Weighted Graph-Based Handover Strategy for Aeronautical Traffic in LEO SatCom Networks\nYear: 2022\n\nAbstract: With the development of space-air-ground integrated network (SAGIN), the Low Earth Orbit Satellite Communication (LEO SatCom) network has great potential to provide high rate communication services for aeronautical traffic. To overcome the frequency handovers between aircraft and LEO satellites, we generated a global aeronautical traffic demand map and utilized the graph-based handover (GBH) framework and the multi-attribute decision making (MADM) algorithm jointly to optimize the overall throughput. Moreover, we further propose a new parameter, called channel reservation order (CRO), for MADM algorithm. Simulation results indicate our strategy improves the performance in terms of overall throughput and access failure probability.","Title: On Scheduling Policy for Multiprocess Cyber–Physical System With Edge Computing\nYear: 2022\n\nAbstract: In this article, we consider a cyber–physical system (CPS) with multiple Internet of Things (IoT) devices. There are multiple independent linear time-invariant processes in the system, which are sampled by sensors, scheduled by controllers, and controlled by actuators. In the literature of wireless control CPS, commonly assume that the system just have one controller and ignore the processing time on server. In this work we employ the edge computing, the controllers are facilitated by edge server and cloud server. The processing time of status update depends on the characteristic of different servers and processes. By taking into account such conditions, we mainly investigate how to choose the destination of status updates (i.e., edge server or cloud server) to minimize the average mean square error (MSE) of the entire system. To address this issue, we formulate a Markov decision process (MDP) problem and obtain the optimal scheduling policy. The threshold property of the optimal scheduling policy is proved, and a suboptimal policy is proposed to overcome the curse of dimensionality. Furthermore, the processing preemption mechanism is considered to schedule the status updates more flexibly, and its consistency property is proved. The simulation results illustrate that the selection of controller is related to the timeliness of process and show the superiority of the proposed policies.","Title: Analysis and Optimization of the HARQ-Based Spinal Coded Timely Status Update System\nYear: 2022\n\nAbstract: The age of information (AoI) is a new metric to measure the timeliness of various status update systems, and hybrid automatic repeat request (HARQ) transmission scheme is usually applied to ensure higher timeliness. However, little research considers encoding delay, propagation delay, decoding delay and feedback delay in the HARQ-based coded status update system. To the best of our knowledge, in this paper, the HARQ-based Spinal coded timely status update system with all the practical delay elements is considered for the first time. We derive the average AoI expression of the system and analyze the monotony of the AoI expression to give an average AoI upper bound. Then we optimize the HARQ transmission scheme to minimize the AoI. To decrease the complexity of the optimization algorithm, we separate it into two steps. First, we optimize the puncturing pattern of Spinal codes and propose a transmission scheme under incremental tail transmission puncturing (ITTP) pattern. Second, we optimize the number of symbols in each round under the ITTP transmission scheme, and propose the optimal transmission scheme under the coarse-grained ITTP pattern. Simulation results show that the proposed transmission scheme can significantly decrease the AoI compared to the baseline transmission schemes."],"string":"[\n \"Title: Smart active object: a new object-oriented programming paradigm for developing multithreaded applications\\nYear: 2002\\n\\nAbstract: Multithreaded programming has been widely used nowadays, but developing mutlithreaded applications is still a tough task. To alleviate such kind of work we propose a new concept, Smart Active Object, an extension to the normal object in object-oriented technology. Smart Active Object runs concurrently with the main execution logic of the program, leveraging multithreading mechanisms and meanwhile leaves only sequential interfaces for programmers to insert application-specific parts, masking details of multithreading, which eventually enhances programming productivity. To support our claims, we design and implement a framework comprising a collection of cooperative Smart Active Objects for stateful applications, a typical problem in telecom world. Using this framework, we easily solve a toy problem, derived from the behavior of SIP stateful proxy servers within much shorter time than a conventional C version counterpart.\",\n \"Title: Rimless wheel with asymmetric flat feet.\\nYear: 2010\\n\\nAbstract: The purpose of this paper is to have a better understanding of the function of human flat foot. To analyze its dynamics, we propose a passive rimless wheel with asymmetric flat feet. The model has a point mass in center and massless spokes. The rigid asymmetric flat feet were equipped at the end of spokes. The walking process of this model which has \\\"heel-strike\\\" and \\\"toe-strike\\\" is similar to human walking which has two peaks of vertical contact force in one stride. The stability was analyzed through eigenvalues of the linearized return map. The energy efficiency was analyzed in two ways, one from CoM trajectory and collision angle, another one from speed and step length. The proposed model has faster walking speed, higher energy efficiency, but lower local stability, compared with regular rimless wheel. © 2010 IEEE.\",\n \"Title: A Robust Boosting Regression Tree with Applications in Quantitative Structure-Activity Relationship Studies of Organic Compounds.\\nYear: 2011\\n\\nAbstract: A regression tree (RT) was extensively utilized in quantitative structure activity relationship studies (QSAR), due to its inherently promising attributes. The issues of instability and inclination to overfitting and suboptima, however, often occur in RT. In the present study, a robust version of boosting was invoked to simultaneously improve the stability and generalization ability of RT, forming a new method called robust boosting regression tree (RBRT). RBRT works by sequentially employing the RT method to model the robustly reweighted versions of the original training set and then aggregating these resultant predictors via weighted median. The designed RBRT was applied to predict the bioactivities of flavoniod derivatives and the anti-HIV activities of HIV-1 inhibitors, compared with boosting RT (BRT) and RT. The results of these two data sets demonstrated that the introduction of robust boosting drastically enhances the stability and generalization ability of RT, and RBRT is superior to BRT in QSAR studies.\",\n \"Title: A tactical intelligence production model of computer network self-organizing operations\\nYear: 2010\\n\\nAbstract: In this paper, we define the concepts of target's information and intelligence activities for Computer Network Self-organizing Operations, propose a tactical intelligence production model of computer network self-organization operation and prove its reachability. In order to verify the model, we present the evaluating, analysis and interpreting algorithm based on rule-based reasoning. Then, we design and implement the tactical intelligence production prototype to verify the validity of the CNSOO-TIPM and algorithms. The experiment results show that the prototype provides timely and accurate intelligence information for the CNO decision and meets the most basic needs of cooperative operations between the CNO agents.\",\n \"Title: Burst mode to strip-map mode SAR interferometry of ALOS PALSAR\\nYear: 2010\\n\\nAbstract: A complete processing flow is proposed to implement burst mode to strip-map mode interferometry for ALOS PALSAR data. The processing flow is applied to an interferometric pair comprised of FBD (High Resolution mode [Dual polarization], belonging to strip-map mode) and WB1 (Wide observation mode, belonging to burst mode) mode of PALSAR. Interferometric products including differential interferometric phase and DEM are generated. The evaluation of these products shows satisfactory precision.\",\n \"Title: The Application of BP Neural Network in the Fault Diagnosis of Rotating Machinery\\nYear: 2011\\n\\nAbstract: BP neural network is effective for deaLing with non-Linear mapping which could satisfactorily describe the non-Linear relations between frequency character and diagnosis results. So the de-noising and feature extraction methods of rotating machinery is discussed in this paper, and a diagnosis model for rotating machinery based on BP neural network is proposed and set up. Then, emulates the model of diagnosis of BP neural network through using MATLAB. Experiment results show that the proposed method based on BP neural network has high practical value in the rotating machinery fault diagnosis.\",\n \"Title: Modified particle swarm optimization algorithm for adaptively configuring globally optimal classification and regression trees.\\nYear: 2009\\n\\nAbstract: The configuration of classification and regression trees (CART) used to include tree-growing by greedy recursive partitioning, which selects the splitting parameters (i.e., splitting variables and values) involved in tree, and tree-pruning, which aims to obtain a final tree of right size. This method is successful for most applications; however, it presents some well-known limitations and drawbacks, such as, less comprehensibility, inclination to overfitting, and suboptima. In the present study, the modified discrete particle swarm optimization method was invoked to adaptively configure the globally optimal CART (MPSOCART) via simultaneously selecting the optimal splitting parameters in CART and the appropriate structure of CART. A new objective function was formulated to decide the appropriate CART architecture and the optimum splitting parameters. The proposed MPSOCART was applied to predict the bioactivities of flavonoid derivatives and inhibitory activities of inhibitors of epidermal growth factor receptor tyrosine kinase, compared with partial least-squares and CART induced by greedy recursive partitioning. The comparison revealed that MPSO was a useful tool for inducing a globally optimal CART, which converges fast to the optimal solution and avoid overfitting in great extent.\",\n \"Title: An Assessment of ScanSAR Interferometric Processing Using Full-Aperture Approach\\nYear: 2014\\n\\nAbstract: Scanning synthetic aperture radar (ScanSAR) interferometry using full-aperture approach has been used in the geophysical community when a standard ScanSAR interferometric processor is not available. Although interferograms can routinely be produced as well, some concerns about the full-aperture processing still remain. In this letter, we assess the quality of the interferogram produced by this approach. After theoretical analyses, we compare interferograms produced by the full-aperture approach and the standard burst-by-burst approach. Comparison results show that the difference between the final interferograms produced by the two approaches is small. For the data processed, the mean value and standard deviation of the difference phase are 8.36 ×10-4 rad and 3.60 ×10-1 rad, respectively. These results confirm the availability of full-aperture processing for most of the geophysical applications using ScanSAR interferometry.\",\n \"Title: ExpertRank: A topic-aware expert finding algorithm for online knowledge communities\\nYear: 2013\\n\\nAbstract: With increasing knowledge demands and limited availability of expertise and resources within organizations, professionals often rely on external sources when seeking knowledge. Online knowledge communities are Internet based virtual communities that specialize in knowledge seeking and sharing. They provide a virtual media environment where individuals with common interests seek and share knowledge across time and space. A large online community may have millions of participants who have accrued a large knowledge repository with millions of text documents. However, due to the low information quality of user-generated content, it is very challenging to develop an effective knowledge management system for facilitating knowledge seeking and sharing in online communities. Knowledge management literature suggests that effective knowledge management should make accessible not only written knowledge but also experts who are a source of information and can perform a given organizational or social function. Existing expert finding systems evaluate one's expertise based on either the contents of authored documents or one's social status within his or her knowledge community. However, very few studies consider both indicators collectively. In addition, very few studies focus on virtual communities where information quality is often poorer than that in organizational knowledge repositories. In this study we propose a novel expert finding algorithm, ExpertRank, that evaluates expertise based on both document-based relevance and one's authority in his or her knowledge community. We modify the PageRank algorithm to evaluate one's authority so that it reduces the effect of certain biasing communication behavior in online communities. We explore three different expert ranking strategies that combine document-based relevance and authority: linear combination, cascade ranking, and multiplication scaling. We evaluate ExpertRank using a popular online knowledge community. Experiments show that the proposed algorithm achieves the best performance when both document-based relevance and authority are considered.\",\n \"Title: Real Scene Oriented Chinese Text Automatic Proofreading Technology.\\nYear: 2013\\n\\nAbstract: Traditional Chinese text automatic proofreading technology is mainly focused on one or more pre-set error types, the proofreading performance in a real scene needs to be improved. This paper proposes a real scene oriented Chinese text proofreading system model for Chinese text automatic proofreading. Real scene oriented Chinese text automatic proofreading strategy is provided after analyzing performance requirements of automatic proofreading system for the real scene. The model is expected to provide new thoughts for future development of proofreading for Chinese text. © 2013 Springer-Verlag.\",\n \"Title: Application for Artificial Bee Colony Algorithm in Migration of Mobile Agent\\nYear: 2010\\n\\nAbstract: The traveling agent problem is a complex combinatorial optimization problem, which solves the problem of planning out an optimal migration path according to the tasks when agents migrate to several hosts in the shortest time. Evolutionary algorithm such as ACO has the well characteristic for heuristic search and robustness. But it has the limitation for the stagnation in the searching. This problem will cause the agent wasting more time in tasking. To avoid it an improved algorithm based on artificial bee colony is introduced. This algorithm uses three kinds of roles: Blaze, Reconnaissance and Follow to routing and finishing the tasks. Agents of the role exchange the information to adopt their own path. The whole group can get the more efficiency path during migration. The experiments show this algorithm has better results in some aspects which needs less times and load for host comparing with the other evolutionary algorithm.\",\n \"Title: On the Phase Compensation of Short ScanSAR Burst Focused by Long Matched Filter for Interferometric Processing\\nYear: 2014\\n\\nAbstract: Scanning synthetic aperture radar (ScanSAR) uses a burst technique to image very large swaths and is widely used in spaceborne SARs. Many algorithms have been proposed to focus ScanSAR burst with its phase preserved so that the focused burst can be used in interferometry to acquire large scale geophysical information, such as land deformation and digital elevation model. However, nearly all of the algorithms leave the focused burst with an additional quadratic phase term that will affect subsequent interferometric processing in the case of short burst. With this phase term, the spectrum of the focused burst is altered according to the principle of stationary phase. Therefore, some processing, such as bandpass filtering, cannot produce desired results if routinely performed. To avoid the effects of the phase term and the nonstationary azimuth spectrum of the burst, a phase compensation scheme is suggested, combining with current focusing algorithms. Simulation experiments are designed to show the effects of the phase term on bandpass filtering. These effects are further verified by a few experiments using real SAR data in unsynchronized signal removal that is frequently required in repeat-pass ScanSAR interferometry. The new phase compensation scheme is tested in real SAR data experiments and works well.\",\n \"Title: Vehicle defect discovery from social media\\nYear: 2012\\n\\nAbstract: A pressing need of vehicle quality management professionals is decision support for the vehicle defect discovery and classification process. In this paper, we employ text mining on a popular social medium used by vehicle enthusiasts: online discussion forums. We find that sentiment analysis, a conventional technique for consumer complaint detection, is insufficient for finding, categorizing, and prioritizing vehicle defects discussed in online forums, and we describe and evaluate a new process and decision support system for automotive defect identification and prioritization. Our findings provide managerial insights into how social media analytics can improve automotive quality management.\",\n \"Title: Calibration of airborne interferometric SAR data by external dem without artificial calibrators\\nYear: 2012\\n\\nAbstract: It is necessary to calibrate interferometric system parameters in order to achieve high accuracy of DEM. The traditional calibration method use a lot of ground artificial calibrators as ground control points. However, the number of calibrators is limited and the distribution is difficult in some mountainous areas. The paper presents a calibration method based on an external DEM without any artificial calibrators. A simulated SAR image was generated with the aid of this reference DEM and a number of tie points were selected to be ground control points. This calibration method can improve the DEM accuracy, and this paper also illustrates its efficient application to airborne interferometric SAR data.\",\n \"Title: What's buzzing in the blizzard of buzz? Automotive component isolation in social media postings\\nYear: 2013\\n\\nAbstract: In the blizzard of social media postings, isolating what is important to a corporation is a huge challenge. In the consumer-related manufacturing industry, for instance, manufacturers and distributors are faced with an unrelenting, accumulating snow of millions of discussion forum postings. In this paper, we describe and evaluate text mining tools for categorizing this user-generated content and distilling valuable intelligence frozen in the mound of postings. Using the automotive industry as an example, we implement and tune the parameters of a text-mining model for component diagnostics from social media. Our model can automatically and accurately isolate the vehicle component that is the subject of a user discussion. The procedure described also rapidly identifies the most distinctive terms for each component category, which provides further marketing and competitive intelligence to manufacturers, distributors, service centers, and suppliers.\",\n \"Title: ScanSAR interferometric processing using existing standard InSAR software for measuring large scale land deformation\\nYear: 2013\\n\\nAbstract: Scanning synthetic aperture radar (ScanSAR) mode is an efficient way to map large scale geophysical phenomena at low cost. The work presented in this paper is dedicated to ScanSAR interferometric processing and its implementation by making full use of existing standard interferometric synthetic aperture radar (InSAR) software. We first discuss the properties of the ScanSAR signal and its phase-preserved focusing using the full aperture algorithm in terms of interferometry. Then a complete interferometric processing flow is proposed. The standard ScanSAR product is decoded subswath by subswath with burst gaps padded with zero-pulses, followed by a Doppler centroid frequency estimation for each subswath and a polynomial fit of all of the subswaths for the whole scene. The burst synchronization of the interferometric pair is then calculated, and only the synchronized pulses are kept for further interferometric processing. After the complex conjugate multiplication of the interferometric pair, the residual non-integer pulse repetition interval (PRI) part between adjacent bursts caused by zero padding is compensated by resampling using a sinc kernel. The subswath interferograms are then mosaicked, in which a method is proposed to remove the subswath discontinuities in the overlap area. Then the following interferometric processing goes back to the traditional stripmap processing flow. A processor written with C and Fortran languages and controlled by Perl scripts is developed to implement these algorithms and processing flow based on the JPL/Caltech Repeat Orbit Interferometry PACkage (ROI_PAC). Finally, we use the processor to process ScanSAR data from the Envisat and ALOS satellites and obtain large scale deformation maps in the radar line-of-sight (LOS) direction.\",\n \"Title: Design and realization of local oscillator for VHF survival receiver.\\nYear: 2010\\n\\nAbstract: Local oscillator is an important device for survival radio system receiver. In this paper, a simple design and flexible configuration, local oscillator using DDS (Direct Digital Frequency Synthesis) technology has been designed and realized. Concerning with double conversion superheterodyne RF Front-End for the receiver, the local oscillator is to generate two channel sinusoidal signals whose frequencies are 130 and 70 MHz separately. The local oscillator consists of a CPLD (complex programmable logic device), two DDS chips, two crystal oscillators, and two low pass filters. The CPLD serving as the controller controls the operation of two DDS chips. The control parameters are stored in the UFM (User Flash Memory) block embedded in the CPLD. The complexity of the circuit is reduced effectively by synchronous serial communication protocol scheme applied between the CPLD and two DDS chips. Simulation and experiment results show that the logic circuit design of the controller is correct and the local oscillator has a good performance. © 2010 IEEE.\",\n \"Title: A New Method of Removing Unsynchronized Signal for ScanSAR Interferometry\\nYear: 2013\\n\\nAbstract: We have analyzed most of the commonly used burst-mode focusing algorithms and chose the one that can be easily combined with unsynchronized-signal removal. In order to remove the unsynchronized signal in scanning synthetic aperture radar (ScanSAR) interferometry, we calculate the burst synchronization using satellite state vectors at first. Then, based on the focusing algorithm chosen and the synchronization calculated, we propose a method to remove the unsynchronized signal. The method rejects the unsynchronized phase and keeps all of the magnitude information. It has been tested with simulated Envisat Advanced Synthetic Aperture Radar ScanSAR data, and the result demonstrated that the method could effectively remove the unsynchronized signal for ScanSAR interferometric processing.\",\n \"Title: Geometric calibration and geolocation of airborne SAR images\\nYear: 2012\\n\\nAbstract: The research focuses on airborne SAR geometric calibration. Based on Range-Doppler (RD) model, mathematical model of airborne SAR image pixel direct geolocation was derived and objective calibration parameters were determined. A whole geometric calibration procedure was proposed, whose critical techniques had been studied. Through the experiment in Guizhou province, China, the calibration parameters were calculated and validated.\",\n \"Title: Investigating co-seismic deformation of the 2008 Wenchuan earthquake with ALOS SCANSAR interferometric observations.\\nYear: 2010\\n\\nAbstract: On May 12th, 2008, a destructive earthquake of magnitude 8.0 struck Wenchuan. The seismic region is located at the transition zone between Qinghai-Tibet Plateau and the Sichuan Basin, which has a complex geological tectonic background. In this paper, we intend to investigate the Wenchuan earthquake using the Differential Interferometric SAR(D-InSAR) technique. Due to the large scale of the crustal deformation affected by the disastrous earthquake, SCANSAR images show more advantages than conventional strip-map mode images. And taking account the vegetation conditions, the L band images are suitable than the C band images for our study. Therefore, we choose to use ALOS SCANSAR interferometric observations to obtain a preliminary co-seismic displacement filed of the Wenchuan earthquake.\",\n \"Title: Determination of vertical antenna pattern of high-resolution airborne SAR and radiometric calibration\\nYear: 2012\\n\\nAbstract: An external calibration experiment was held for an airborne SAR. The paper describes the calibration experiment that uses a series of trihedral corner reflectors to calibrate the high-resolution SAR images, including antenna pattern correction and absolute radiometric calibration. In this paper, we specifically address the determination of vertical antenna pattern with multi-flight SAR imaging geometry, and discussion of the absolute calibration methods. First, three images acquired with variable off-nadir angle from 67.9~78.3, 70.9~78.4, and 72.5~79.8 degree respectively are combined to measure the antenna pattern with off-nadir angle from 67~80 degree. And then three images were relatively calibrated on the uniform standard based on the uniform antenna pattern. Secondly, the absolute calibration factor is inferred with two methods called average method and linear regression method, and the result is compared and analyzed. The experimental results show that our calibration method with several images together to acquire the large antenna pattern is feasible. And these images achieve a uniform relative calibration even though the different images have different imaging geometry and radiometric characteristics. After absolute calibration, the estimated RCS of each corner reflector basically reached agreement with the actual RCS, and the estimated error from the calibrated image for most of corner reflectors is less than 1.0dB.\",\n \"Title: A Novel Hybrid Method To Unwrapping Interferometric Phase\\nYear: 2004\\n\\nAbstract: Phase Unwrapping is the most difficult and unavoidable problem in the interferometric synthetic aperture radar (InSAR) processing procedures. lntensive researches have been done and the methods proposed were summaried into two categories: path following and minimum norm. Unwrapping result by path following is congruent with wrapped phase and require less time and memory. While minimum norm method usually could not obtain congruent result directly and take more Computing resource. Weighting could improve base unwrapping result much if the suspicious region could be correctivelty separated out by weighting function. However, common used weighting such as coherence or phase gradiant could not serve this purpose very well. In this paper, we proposed a novel method to unwrap phase, which combined the advantages of both categories, and set weight based on phase unwrapping consistence. We demonstrated the method with real InSAR phase. The unwrapping result showed the novel method could recover the dynamic range of phase than least square method while keep correct trend.\",\n \"Title: Simulation And Analysis Of Microwave Emissivity And Opacity Of Winter Wheat By Radiation Transfer Method\\nYear: 2003\\n\\nAbstract: Measuring soil moisture is very important for monitoring global water cycle. In past years more than two decades, measuring soil moisture by passive and active microwave remote sensing has been intensively researched [3, 4, 6, 7]. The significant advancements has been made in measuring soil moisture in bare soil field or less vegetation covered region. To measure soil moisture with vegetation cover, vegetation emissivity and opacity have to be included as two parameters to character radiation in vegetation layer. In this paper, we reviewed the phenomenological model to treat radiation transfer in media comprised of vegetation and underlying soil surface. And then simulation of vegetation emissivity and opacity based on radiation transfer theory and combined with input of geometrical parameters and water content measured in winter wheat field was presented. Finally, the relationships between them, in particular of different frequencies and polarization, were been dug out and examined.\",\n \"Title: A dynamic stochastic frontier model to evaluate regional financial efficiency: Evidence from Chinese county-level panel data.\\nYear: 2015\\n\\nAbstract: Studies have widely used stochastic frontier models to assess financial efficiency; however, traditional static approaches do not take dynamic characteristics of financial systems into account. This article develops a dynamic stochastic frontier model to evaluate regional financial efficiency and provides an empirical test of the model by using panel data of 62 Chinese counties during the 2001–2010 period. The model measures the dynamic impact of the input–output variables and environmental variables on financial efficiency, and allows for the separation of technical change from the change in technical efficiency. The results show that the dynamic model provides a better fit to the data than the static model. In addition, a gradient difference emerges in the regional financial efficiency among the six major regions of China. The results offer practical implications for the development of regional financial services in China, as well as other developing countries and emerging economies.\",\n \"Title: Improvement of PS-InSAR atmospheric phase estimation by using WRF model\\nYear: 2014\\n\\nAbstract: As a component of interferometric phase, atmospheric phase influences accuracy of millimetric land deformation measurement. Though Atmospheric Phase Screen (APS) can be estimated by Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technology, they are pseudo without consideration of actual atmospheric state and topography. This paper researches into ineffective separation of atmospheric phase in PS-InSAR methods when applied to extended cloudy area, and proposes an improved PS-InSAR processing flow by introducing Weather Research Forecast (WRF) simulations to remove atmospheric phase before interferometric phase analysis of PSI technique to obtain accurate land deformation velocity.\",\n \"Title: A new user-oriented remote sensing information service model based on integrated platform\\nYear: 2014\\n\\nAbstract: In this paper, we propose a novel user-oriented information service model for the development trend of remote sensing information service industrialization. Traditional remote sensing information service model is often a typical product-oriented service model, which is unable to make the most use of the existing resource nowadays. From the perspective of information service model, this research analyzes the defects of traditional remote sensing service model and the technical development of remote sensing service, puts forward the new remote sensing information service model based on integrated platform, and notes its advantages than the traditional model. At last, this paper explores the possible technical difficulties for the implement of the new service model.\",\n \"Title: Fusion of multi-frequency interferometric results by using Kalman filter to generate high quality DEM\\nYear: 2014\\n\\nAbstract: Using conventional two-pass interferometry to generate DEM with high frequency SAR data may be confronted with the problem of poor coherence in areas covered by dense vegetation, while DEM generated from low frequency SAR data interferometry is less sensitive to the topographic relief. Therefore, this article aims at generating high quality DEM by fusing multi-frequency interferometric results obtained from two-pass interferometry by using Kalman filter. Meanwhile, a process of coregistration of multi-frequency SAR data which are of different pixel sizes and imaging geometries is proposed. And data from Envisat ASAR and TerraSAR-X are used for case study and the accuracy of fused DEM are verified by ASTER GDEM.\",\n \"Title: Research of InSAR atmospheric correction using WRF model simulated result and MERIS product\\nYear: 2012\\n\\nAbstract: Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to study the co-seismic displacement field of earthquakes. With the development of D-InSAR technique, the removal of the atmospheric effect has been the main focus points of research to reduce the InSAR LOS displacement measurement error. Previous studies have shown that the MERIS water vapor product is one of the best choices for ASAR data to reduce the atmospheric effect in cloudless weather conditions. In this paper, we use the combination of the simulated results with WRF model and MERIS water vapor product to reduce the atmospheric effect in some cloudy weather condition.\",\n \"Title: Error correction method based on data transformational GM(1, 1) and application on tax forecasting.\\nYear: 2015\\n\\nAbstract: This paper provides an overview of the existing prediction methods, and then put forward a new approach for the improvement of prediction accuracy by introducing error correction. The characteristics of this method are to make full use of some valuable information contained in the error value. Its main idea is that the accelerated translation transforms and weighting mean value generating transforms are introduced to deal with prediction error sequence, so as to analyze the distribution of the prediction error and construct the error correction method based on data transformational GM(1,1),which is used to predict the subsequent error. And then, the predictive value of error is used to adjust the initial predicted revenue. After data transformation, the new sequences are much less volatile than before, and the smooth degree also becomes small. And to be more credible, case study verifies that this method has a better fitting effect and higher prediction precision. An error correction method is proposed to improve forecasting accuracy.This algorithm is integrated with LS-SVR and data transformation GM(1,1).This method emphasizes on the importance of making full use of error informationProposed algorithm is well suited for the characteristics of prediction error.The approach is superior to traditional forecasting methods. Accurate tax forecast is very important to carry on the macroscopic regulation efficiently under the market economy. However, experience shows that it is very difficult to improve the accuracy of forecasting by setting up a single forecasting model. This article describes the deficiencies of the present forecasting methods and puts forward a new approach to improve the accuracy of prediction by introducing error correction. First, this paper carries out initial prediction of tax revenue by using the LS-SVR model. Second, the accelerated translation transform and weighting mean value generating transform are introduced to process the error sequence. On the basis of the processed data, the error predictive method based on data transformational GM(1,1) is constructed and predicts the subsequent error. Third, the correction of preliminary prediction values is calibrated. The case study based on Chinese tax revenue during the last 30 years shows that the presented approach improves the accuracy of forecasting significantly compared with the prediction accuracy before correction, and then the validity of the model is verified.\",\n \"Title: A Novel Approach To Building Collapse Detection From Post-Seismic Polarimetric Sar Imagery By Using Optimization Of Polarimetric Contrast Enhancement\\nYear: 2015\\n\\nAbstract: A novel approach is proposed in this paper for earthquake-induced building collapse extraction based on the optimization of polarimetric contrast enhancement (OPCE). This method can realize a quick building damage assessment since the data it requires is one post-event fully polarimetric Synthetic Aperture Radar (PolSAR) image. In this method, collapsed building is recognized as clutter and the optimal polarization states are determined based on building samples with different orientation angles. For comparison, another contrast enhancement methodology, polarization synthesis technology is also utilized. We tested these two methods by using one Radasat-2 PolSAR image from Yushu earthquake in Qinghai province of China occurred in 2010. Results were validated by manual interpretation results of very high resolution (VHR) optical image. Experiments shows that collapsed building detection accuracy of OPCE method can be 66.53% in average, which is higher than that of polarization synthesis technology (42.7%) for the reason that building orientation is considered in the data processing of OPCE method.\",\n \"Title: Study On The Production Cost Pricing Model Of Quantitative Remote Sensing Products\\nYear: 2015\\n\\nAbstract: Since the forming of sustainable business models of remote-sensing products and services will be an inevitable development trend, it is necessary to design the specific and rational pricing model for quantitative remote sensing products (QRSPs). Based on the production procedures, this paper presents a production cost pricing model of QRSPs, to achieve the conversion from abstract factors of production cost to the pricing parameters that can be operated in the actual cost pricing. The pricing model is devised as the addition model so that it can fulfill the diverse acquirements of customized production. The valuation of common products of China Remote Sensing Network indicated that the pricing model could be well-operated in theory.\",\n \"Title: High Precision Airborne Sar Geometric Calibration And Geolocation Based On An Improved Near Range Model\\nYear: 2015\\n\\nAbstract: The research focuses on high precision airborne SAR geometric calibration (GC) and geolocation (GL) on the condition of long flight time.The experiment was conducted in Inner Mongolia, China, and based on image pixels' GL model, calibration parameters and procedure proposed in literature [1], two systematic parameters (near range R-0 and slant range resolution rho(r)) were calculated and validated. But, compared with the method in literature [1], improvements were mainly made on two aspects: firstly, Cubic spline rather than simple polynomial was used in this research to fit POS data so as to get a more accurate SAR antenna's position and velocity at zero Doppler time; secondly, through analysis of distribution of corner reflectors' GL errors, slant range (or near range) error was identified as main factor affecting GL, then an improved near range model was computed, validated and used to improve the accuracy of GL.Through the experiment in Inner Mongolia, the accuracy of GL in X and Y direction was 1m and 0.26m respectively, and after introducing the improved near range model, the accuracy of GL can be increased by about 10%.\",\n \"Title: A New Method For Building Collapse Detection Jointly Using Interferometric And Polarimetric Information\\nYear: 2015\\n\\nAbstract: Earthquake is one of the most catastrophic disasters to affect mankind especially in urban areas. Reliable and fast collapsed building detection is vitally important to timely rescue and scientific decision making. A modified detection method for collapsed buildings is proposed in this paper by jointly using interferometric information and polarimetric information. The method was tested on two single-polarimetric ALOS PALSAR images and one fully polarimetric Radarsat-2 image from Yushu earthquake in Qinghai province of China occurred in 2010. After compared with manual interpretation results of very high resolution (VHR) optical image, collapsed building detection accuracy can be 72.77%. The accuracy is improved by about 30% compared with that of only coherence based method.\",\n \"Title: Deep Crossing: Web-Scale Modeling without Manually Crafted Combinatorial Features\\nYear: 2016\\n\\nAbstract: Manually crafted combinatorial features have been the \\\\\\\"secret sauce\\\\\\\" behind many successful models. For web-scale applications, however, the variety and volume of features make these manually crafted features expensive to create, maintain, and deploy. This paper proposes the Deep Crossing model which is a deep neural network that automatically combines features to produce superior models. The input of Deep Crossing is a set of individual features that can be either dense or sparse. The important crossing features are discovered implicitly by the networks, which are comprised of an embedding and stacking layer, as well as a cascade of Residual Units. Deep Crossing is implemented with a modeling tool called the Computational Network Tool Kit (CNTK), powered by a multi-GPU platform. It was able to build, from scratch, two web-scale models for a major paid search engine, and achieve superior results with only a sub-set of the features used in the production models. This demonstrates the potential of using Deep Crossing as a general modeling paradigm to improve existing products, as well as to speed up the development of new models with a fraction of the investment in feature engineering and acquisition of deep domain knowledge.\",\n \"Title: Force Maintenance Accuracy Using a Tool: Effects of Magnitude and Feedback.\\nYear: 2016\\n\\nAbstract: The ability to precisely produce a force via a hand-held tool is crucial in fine manipulations. In this paper, we study the error in maintaining a target force ranging from 0.5 to 5 N under two concurrent feedback conditions: pure haptic feedback (H), and visual plus haptic feedback (V + H). The results show that absolute error (AE) increases along with the increasing force magnitudes under both f...\",\n \"Title: A Geocoding Method For Sar Image Based On Tin Lookup Table\\nYear: 2016\\n\\nAbstract: A geocoding method for SAR image based on Triangulated Irregular Network (TIN) lookup table is proposed in this paper. Firstly, TIN DEM is generated from Grid DEM. Then, each node in TIN DEM is geocoded by Range-Doppler model to produce a TIN lookup table. Finally, geocoded image is resampled by TIN lookup table. Experimental results show TIN lookup table can reduce file size with losing less precision, which compared with original Grid lookup table. Although TIN lookup table takes some time to create TIN DEM from Grid DEM, it takes less time than original lookup table in geocoding process. So it could save running time for large number of SAR images geocoding in the same area. TIN lookup table can balance between precision and file size, when its height tolerance approximately is less than accuracy of DEM products.\",\n \"Title: Measurement Crustal Movement Along Altyn Tagh Fault By Using Multimode Insar Time Series Analysis\\nYear: 2016\\n\\nAbstract: High-coherent pixels detection and spatial coverage restriction are the key difficulties when applying the InSAR time series analysis in Altyn Tagh Fault (ATF) system based on stripmap SAR data. In this paper, a modified InSAR time series analysis method combining PS and DS is presented in order to increase the number of selected high-coherent pixels. Then a displacement velocities merging strategy by fitting least squares surfaces is proposed, which could decrease the velocities differences in overlap area between adjacent stripmap SAR tracks, so as to acquire the deformation results of the whole research area. Moreover, in order to avoid the merging problem caused by the inconsistent measurements between adjacent stripmap SAR tracks, processing strategies of ScanSAR PS-InSAR and ScanSAR SBAS are presented respectively. All of the methodology we proposed have been applied to the crustal movement measurement along the west section of ATF and reliable results have been acquired.\",\n \"Title: A New Framework Of Building Collapse Extraction Based On Azimuth Time-Frequency Analysis\\nYear: 2016\\n\\nAbstract: Rapidly obtaining building damage information after the earthquake is vitally important to earthquake rescue and decision making. In this paper, we propose a new framework of building collapse extraction by combining polarimetric information and azimuth time-frequency analysis. The proposed framework consists of two main steps, i.e. open area removal and intact building identification. In the first step, we introduce the Shannon entropy to polarimetric parameters derived from H/Lambda/alpha decomposition to remove open areas. Since intact buildings with orientation angles present a similar scattering mechanism to collapsed buildings, it seriously hampers the building collapse extraction accuracy. To solve this problem, in the second step we try to use azimuth time-frequency analysis to eliminate this deficiency. In the azimuth direction, sub-aperture images are obtained by spectrum splitting, which corresponds to observe the targets from different azimuth look angles. The nonstationary discrimination method is used combined with the SPAN parameter to identify intact buildings including intact buildings with orientation angles. The feasibility of the second step has been demonstrated by using E-SAR PolSAR data. The potential advantage of the proposed framework when we apply it to the earthquake-induced building collapse extraction includes that only one post-earthquake polarimetric SAR (PolSAR) image is needed. Moreover, orientated intact buildings can be identified and the final accuracy of building collapse extraction can be probably improved as a result.\",\n \"Title: Quantitative Analysis Of The Water Vaopr Effects On The Interferometric Measurements\\nYear: 2016\\n\\nAbstract: The water vapor plays an important role on the microwave propagation. Plenty of methods to reduce its effects in the differential InSAR technique have been put forward, such as using MERIS, MODIS, GPS and the weather models. In order to analyze the water vapor effects quantitatively, we selected several time-series related Envisat ASAR images with their corresponding synchronous MERIS Full Resolution water vapor products. First of all, we analyze the quantitative relationship between the water vapor delay and the local elevation and find that there is no obvious linear correlation between water vapor and elevation. Then, we make a comparison between the InSAR measurements without water vapor correction and measurements with water vapor correction. The results indicate that the removal of the water vapor delay and the baseline refinement are coupled together. And at the same time, the influence of water vapor can lead to error of at least 10 mm.\",\n \"Title: Throughput-Optimal Scheduling for Multi-Hop Networked Transportation Systems With Switch-Over Delay.\\nYear: 2017\\n\\nAbstract: The emerging connected-vehicle technology provides a new dimension for developing more intelligent traffic control algorithms for signalized intersections. An important challenge for scheduling in networked transportation systems is the switchover delay caused by the guard time before any traffic signal change. The switch-over delay can result in significant loss of system capacity and hence needs to be accommodated in the scheduling design. To tackle this challenge, we propose a distributed online scheduling policy that extends the well-known Max-Pressure policy to address switch-over delay by introducing a bias factor favoring the current schedule. We prove that the proposed policy is throughput-optimal with switch-over delay. Furthermore, the proposed policy remains optimal when there are both connected signalized intersections and conventional fixed-time ones in the system. With connected-vehicle technology, the proposed policy can be easily incorporated into the current transportation systems without additional infrastructure. Through extensive simulation in VISSIM, we show that our policy indeed outperforms the existing popular policies.\",\n \"Title: On the Pixel Expansion of Visual Cryptography Scheme.\\nYear: 2017\\n\\nAbstract: In this paper, we first follow Ateniese et al.'s work that provides upper bounds of the pixel expansion of visual cryptography schemesVCSs for more kinds of graph access structures, in which we require that a subset of parties can determine the secret if they contain an edge of the graph G. The constructive upper bounds are derived by the graph decomposition technique. Then we generalize Ateniese et al.'s method of comparing the optimal pixel expansion of VCSs with two different access structures.\",\n \"Title: Absolute and discrimination thresholds of a flexible texture display\\nYear: 2017\\n\\nAbstract: We present a flexible tactile interface, FlexTouch, for simulating texture of fabrics. The FlexTouch displays virtual texture on fingertips based on electrovibration principle. To exam human factors in using FlexTouch, we measured absolute detection thresholds of input voltage with respect to frequencies ranging from 30 to 300 Hz. The measured thresholds formed a U-shaped curve indicating a minimum value of 23 Vpp at the frequency of 169 Hz. We then measured the just-noticeable-differences (JNDs) of the voltage amplitudes ranging from 71 to 225 V at the most sensitive frequency, i.e. 169 Hz. The result suggests that the JNDs depend linearly on the amplitude of stimulus signal. These measures provide guidelines to design interfaces and applications using FlexTouch.\",\n \"Title: Rate-Compatible Transmission Schemes Based on Parallel Concatenated Punctured Polar Codes.\\nYear: 2017\\n\\nAbstract: In this paper, an improved random puncturing pattern of polar codes is proposed, where only the frozen bits can be selected to puncture. Compared to the existing random puncturing schemes, our improved random puncturing scheme can achieve 0.2-1dB decoding performance improvement. Then, an optimized rate-compatible hybrid automatic repeat request (HARQ) transmission scheme is proposed based on parallel concatenated punctured (PCP) polar codes. By analyzing the overhead of the previous successful decoded coding block in our rate-compatible HARQ scheme, two methods of determining the optimal initial code-rate of each new PCP polar coding block are proposed over a time-varying channel. Simulation results show that the average number of retransmissions is about 1.5 times in our proposed rate-compatible HARQ schemes with a 2-level PCP polar encoding construct, which reduces half of the average number of retransmissions than the existing rate-compatible polar coding scheme.\",\n \"Title: Resilience Optimization for Complex Engineered Systems Based on the Multi-Dimensional Resilience Concept.\\nYear: 2017\\n\\nAbstract: Most traditional engineered systems are designed with a passive and fixed reliability capability and just required to achieve a possibly low level of failure occurrence. However, as the complexity at spatial-temporal scales and integrations increases, modern complex engineered systems (CESs) are facing new challenges of inherent risk and bottleneck for a successful and safe operation through the system life cycle when potential expected or unexpected disruptive events happen. As a prototype for ensuring the successful operation of inherently risky systems, resilience has demonstrated itself to be a promising concept to address the above-mentioned challenges. A standard multi-dimensional resilience triangle model is first presented based on the concept of the three-phase system resilience cycle, which can provide a theoretical foundation for indicating the utility objectives of resilience design. Then, the resilience design problem for CESs is proposed as a multi-objective optimization model, in which the three objectives are to maximize the survival probability, to maximize the reactive timeliness and to minimize the total budgeted cost. Furthermore, the proposed multi-objective optimization programming is solved based on the efficient multi-objective evolutionary algorithm NSGA-II. Finally, the effectiveness of the proposed models and solving procedure is illustrated with an engineered electro-hydrostatic aircraft control actuator resilience design problem, a comparative analysis on the case study is also carried out with respect to previous works. This work can provide an effective tradeoff foundation to improve the resilience of CESs.\",\n \"Title: Bounds on the error probability of finite-length RaptorQ codes.\\nYear: 2017\\n\\nAbstract: Massive machine-to-machine (mM2M) communication requires data transmission in short packets, but at present, the theory of short length code design and optimazation is still incompletely. In this paper, we analyze the maximum likelihood (ML) decoding failure probability (DFP) of finite length RaptorQ codes, and propose a theoretical performance bound of DFP on the RaptorQ codes under ML decoding algorithm by investigating the rank of the product of two random coefficient matrices. Moreover, we verify the accuracy of derived theoretical bounds through the Monte Carlo simulations over varied Galois field order. The high accuracy bounds can be used to design near-optimum RaptorQ codes with short and moderate lengths.\",\n \"Title: Design and analysis of LTP-HARQ transmission scheme in OSTBC-MIMO systems for SINs.\\nYear: 2017\\n\\nAbstract: Recently, distributed/virtual multiple-input multiple-output (MIMO) technology over satellites have attracted considerable research interest due to the development of Ka-band high throughput satellites (HTS) and space information networks (SINs). In this paper, a novel performance analysis framework is proposed for MIMO with orthogonal space-time block coding (OSTBC) under Licklider transmission protocol (LTP) for emerging SINs, where we derive the closed-form expressions of the mean number of transmission rounds by using Laplace transform for reliable data delivery in automatic repeat request (ARQ) and hybrid-ARQ (HARQ) schemes. Furthermore, we derive the throughput expressions for lossless-and truncated-(H)ARQ schemes, and obtain the maximum throughput value on information rate. We also investigate the file delivery time in LTP over Rayleigh and Rician fading channels. Simulations results are provided to demonstrate the validity of our theoretical results, and show the effect of antenna number on the system performance.\",\n \"Title: Efficient HARQ scheme based on rate-compatible punctured polar codes.\\nYear: 2017\\n\\nAbstract: In this paper, an optimized parallel concatenated punctured polar (OPCPP) coding scheme is designed to realise the rate-compatible property of polar codes. First, an improved random puncturing pattern of polar codes is proposed to achieve better performance than the random puncturing scheme, which can obtain about 0.2–1dB better than the random puncturing scheme. Then, by analyzing the performance of HARQ transmission scheme via OPCPP coding blocks over slow fading channels, the optimal initial code rate of each new OPCPP coding block can be determined by the overhead of the previous successful decoded coding block. Simulation results show that the mean number of retransmissions in our proposed rate-compatible HARQ scheme is about 1.5 times with the encoding construct of a 2-level OPCPP codes, which can reduce half of the number of retransmissions than the existing rate-compatible polar coding scheme.\",\n \"Title: Behavior Intention Derivation of Android Malware Using Ontology Inference.\\nYear: 2018\\n\\nAbstract: Previous researches on Android malware mainly focus on malware detection, and malware's evolution makes the process face certain hysteresis. The information presented by these detected results (malice judgment, family classification, and behavior characterization) is limited for analysts. Therefore, a method is needed to restore the intention of malware, which reflects the relation between multiple behaviors of complex malware and its ultimate purpose. This paper proposes a novel description and derivation model of Android malware intention based on the theory of intention and malware reverse engineering. This approach creates ontology for malware intention to model the semantic relation between behaviors and its objects and automates the process of intention derivation by using SWRL rules transformed from intention model and Jess inference engine. Experiments on 75 typical samples show that the inference system can perform derivation of malware intention effectively, and 89.3% of the inference results are consistent with artificial analysis, which proves the feasibility and effectiveness of our theory and inference system.\",\n \"Title: Performance Analysis of Space Information Networks with Backbone Satellite Relaying for Vehicular Networks.\\nYear: 2017\\n\\nAbstract: Space Information Network (SIN) with backbone satellites relaying for vehicular network (VN) communications is regarded as an effective strategy to provide diverse vehicular services in a seamless, efficient, and cost-effective manner in rural areas and highways. In this paper, we investigate the performance of SIN return channel cooperative communications via an amplify-and-forward (AF) backbone satellite relaying for VN communications, where we assume that both of the source-destination and relay-destination links undergo Shadowed-Rician fading and the source-relay link follows Rician fading, respectively. In this SIN-assisted VN communication scenario, we first obtain the approximate statistical distributions of the equivalent end-to-end signal-to-noise ratio (SNR) of the system. Then, we derive the closed-form expressions to efficiently evaluate the average symbol error rate (ASER) of the system. Furthermore, the ASER expressions are taking into account the effect of satellite perturbation of the backbone relaying satellite, which reveal the accumulated error of the antenna pointing error. Finally, simulation results are provided to verify the accuracy of our theoretical analysis and show the impact of various parameters on the system performance.\",\n \"Title: A Novel High-Rate Polar-Staircase Coding Scheme.\\nYear: 2018\\n\\nAbstract: The long-haul communication systems can offer ultra high-speed data transfer rates but suffer from burst errors. The high-rate and high-performance staircase codes provide an efficient way for long-haul transmission. The staircase coding scheme is a concatenation structure, which provides the opportunity to improve the performance of high-rate polar codes. At the same time, the polar codes make the staircase structure more reliable. Thus, a high-rate polar-staircase coding scheme is proposed, where the systematic polar codes are applied as the component codes. The soft cancellation decoding of the systematic polar codes is proposed as a basic ingredient. The encoding of the polar-staircase codes is designed with the help of density evolution, where the unreliable parts of the polar codes are enhanced. The corresponding decoding is proposed with low complexity, and is also optimized for burst error channels. With the well designed encoding and decoding algorithms, the polar-staircase codes perform well on both AWGN channels and burst error channels.\",\n \"Title: Social-Aware D2d Caching Content Deployment Strategy Over Edge Computing Wireless Networks\\nYear: 2018\\n\\nAbstract: Caching the popular files in mobile terminal equipments and transferring those files via Device-to-Device (D2D) communication technology can offload the traffic from the Base Station(BS) over edge computing wierless network. The user equipments(UE) are mobile and the D2D communication links may drop any instant. In addition, UEs are carried by people with social attributes. Considering those information about mobile terminals when we study the D2D caching content deployment strategy can improve the caching efficiency. In order to reduce the probability of requesting files from BS, we design an efficient social-aware caching content deployment strategy, which includes the community discovery mechanism, the caching nodes selection algorithm and the file caching probability determination algorithm. Simulation experiments are provided to prove that our D2D caching content deployment strategy can improve the traffic offload rate in edge computing wireless networks.\",\n \"Title: Availability Analysis and Optimal Design of Multistate Weighted k-Out-of-n Systems With Component Performance Requirements.\\nYear: 2018\\n\\nAbstract: As one of the most typical multistate systems, weighted k-out-of-n system has been extensively studied in recent years. This paper presents a new kind of multistate weighted k-out-of-n system, which simultaneously considers performance requirements of each component and the system performance (cumulative performance threshold of all components). Then, we establish a new dynamic availability model by combining the Markov process and universal generating function. Moreover, an optimal design is proposed to achieve a tradeoff between system reliability/availability and cost. Non-dominated sorting genetic algorithm-II is used to optimize the probability and performance of components in different states. Finally, an example is illustrated to evaluate system availability and optimize component design. The optimization design can be referred as an optimal standard in system update.\",\n \"Title: A Smart Post-Rectification Algorithm Based on an ANN Considering Reflectivity and Distance for Indoor Scenario Reconstruction.\\nYear: 2018\\n\\nAbstract: Indoor scene reconstruction is important for robot positioning and navigation in scenario reconstruction, especially in constructing a semantic map. In previous research, RGB-D cameras have been utilized to obtain a semantic map. However, because of indoor objects and depth sensors, the accuracy and precision of the depth values could be improved, which is a key factor in reconstructing indoor scenarios. Moreover, there is a relationship between reflectivity and depth accuracy. Therefore, to obtain depth information that is better than that obtained in our previous research, we present a smart post rectification algorithm based on an artificial neural network (ANN). The algorithm improves the accuracy and precision of depth values by simultaneously considering reflectivity, distances, and different mechanisms of measuring depth. First, we analyze the RGB-D cameras' characteristics, including the pinhole camera model, lens distortions, and the types of error factors due to the types of RGB-D cameras used. Then, this paper proposes a smart post-rectification algorithm for depth images based on an ANN considering the depth error caused by reflectivity, the distance-related depth error, and different mechanisms for measuring depth. Finally, we perform experiments to evaluate the accuracy and precision of the proposed post-rectification approach by using different types of depth sensors. To evaluate the performance of our proposed algorithm, the proposed approach is applied to RGB-D SLAM, which is tested in different indoor environments. The experimental results show that applying our post-rectification algorithm to indoor scenario reconstruction can result in more accurate and more detailed 3-D reconstruction of objects than other state-of-the-art methods, highlighting the robustness and efficiency of our proposed algorithm.\",\n \"Title: MagicVO: End-to-End Monocular Visual Odometry through Deep Bi-directional Recurrent Convolutional Neural Network.\\nYear: 2018\\n\\nAbstract: This paper proposes a new framework to solve the problem of monocular visual odometry, called MagicVO . Based on Convolutional Neural Network (CNN) and Bi-directional LSTM (Bi-LSTM), MagicVO outputs a 6-DoF absolute-scale pose at each position of the camera with a sequence of continuous monocular images as input. It not only utilizes the outstanding performance of CNN in image feature processing to extract the rich features of image frames fully but also learns the geometric relationship from image sequences pre and post through Bi-LSTM to get a more accurate prediction. A pipeline of the MagicVO is shown in Fig. 1. The MagicVO system is end-to-end, and the results of experiments on the KITTI dataset and the ETH-asl cla dataset show that MagicVO has a better performance than traditional visual odometry (VO) systems in the accuracy of pose and the generalization ability.\",\n \"Title: Detection and Discrimination Thresholds for Haptic Gratings on Electrostatic Tactile Displays.\\nYear: 2019\\n\\nAbstract: Designing algorithms for rendering haptic texture on electrostatic tactile displays requires a quantitative understanding of human perception. In this paper, we report detection and discrimination thresholds for haptic gratings rendered on such displays based on the waveform and amplitude of the applied voltage. The haptic gratings consist of functions that describe the variation in voltage amplitude as a function of the position of finger on the display. Four types of virtual haptic gratings are considered in two experiments. In Experiment I, we estimate the absolute detection thresholds of haptic gratings for four different voltage amplitude functions, consisting of spatial waveforms with sinusoidal, square, triangle, or sawtooth shape. In Experiment II, we report discrimination thresholds for haptic gratings at five reference values of the voltage amplitude (80, 120, 160, 200, and 240 Vpp) for each of the voltage amplitude functions used in Experiment I. The results indicate that the detection thresholds for the four virtual haptic gratings are between 30 and 36 Vpp, and that the JND increases with the increase of voltage amplitudes. In addition, the JNDs of the four virtual gratings differ significantly, with the lowest and highest values being given by the triangle and sawtooth waveform, respectively.\",\n \"Title: Outage Analysis of Multirelay Multiuser Hybrid Satellite-Terrestrial Millimeter-Wave Networks.\\nYear: 2018\\n\\nAbstract: In this letter, we investigate the outage probability (OP) performance of a multirelay multiuser hybrid satellite-terrestrial relay network operating at millimeter wave (mmWave) bands. Considering the dominant fading factor of the mmWave band is rain attenuation, we combine the long-term rain attenuation model with the statistical channel model to describe the mmWave channel. Then we utilize expec...\",\n \"Title: Performance Analysis of Uplink Uncoordinated Code-Domain NOMA for SINs\\nYear: 2018\\n\\nAbstract: Space information networks (SINs) are regarded as an effective solution to enable a broadband access capability in a global coverage and cost-effective manner for massive machine type communications (mMTC). A collision often occurs when two or more user equipments (UEs) select the same pilot in mMTCs, and the received colliding signals are treated as interference. In this paper, we first analyze the problem of pilot collision for uplink mMTCs in SIN, then we investigate the performance of an uncoordinated code domain non-orthogonal multiple access (NOMA) protocol. Moreover, to recover the information in collisions, we adopt successive interference cancellation (SIC) and successive joint decoding (SJD) under a shadowed-Rician fading and path loss satellite-ground channel model, and derive the expressions of the outage probability and maximum system throughput for SIC and SJD, respectively. Numerical and simulation results validate our analytical results and show that the maximum system throughput of SJD is almost double that of SIC.\",\n \"Title: The Effect of Applied Normal Force on the Electrovibration.\\nYear: 2019\\n\\nAbstract: Electrovibration has become one of the promising approaches for adding tactile feedback on touchscreen. Previous studies revealed that the normal force applied on the touchscreen by the finger affects significantly the electrostatic force. It is obvious that the normal force affects the electrostatic force if it changes the contact area between the finger and the touchscreen. However, it is unclear whether the normal force affects the electrostatic force when the apparent contact area is constant. In this paper, we estimated the electrostatic force via measuring the tangential force of the finger sliding on a 3M touchscreen at different normal forces under the constant apparent contact area. We found that the electrostatic force increases significantly as the normal force increases from 0.5 to 4.5N. We explained the experimental results using the most recently proposed electrostatic force model, which considers the effect of air gap. We estimated the averaged air gap thickness using the electrostatic force model. The results showed that the relationship between the air gap thickness and the normal force follows a power function. Our experiment suggests that the normal force has a significant effect on the air gap thickness, thus require consideration in the design of tactile feedback.\",\n \"Title: Power Allocation Optimization of Multibeam Satellites for Integrated Satellite-Terrestrial Networks\\nYear: 2018\\n\\nAbstract: The increasing demand for high data rate services over the integrated satellite-terrestrial network has pushed for the development of millimeter-wave (mmWave) band high throughput satellites (HTS) with multibeams. However, existing multibeam HTS is with predetermined beam connection. Considering the mmWave channel is much more sensitive to the weather conditions than the conventional S/C/X band channels, it is important to allocate the limited transmission power to the beams that connect to the ground station in good state. Moreover, due to the huge distance and long propagation delay in the integrated satellite-terrestrial networks, the multibeam HTS can only obtain delayed Channel State Information (CSI) from feedback. In this paper, we model this problem as a Partially Observable Markov Decision Process (POMDP), and propose a power allocation optimization over two identical Gilbert-Elliott beams HTS communication, which can partly mitigate the negative effects of adverse weather conditions. The key thresholds for selecting the optimal power allocation method in the multibeam HTS communications are derived. The effectiveness and potentialities of our proposed scheme is verified through simulation results.\",\n \"Title: Design and Analysis of NCed-HARQ Transmission Scheme for Space Information Networks\\nYear: 2018\\n\\nAbstract: With the development of high throughput satellites and space information networks (SINs), broadband satellite communication networks is viewed as an important component to improve system coverage and throughput in the upcoming fifth generation (5G) networks. In this paper, we propose a network coded (NCed) hybrid automatic repeat request (HARQ) transmission scheme for the backbone high throughput satellites in SINs, in order to satisfy the ever-increasing broadband communication service demands. We first present our NCed-HARQ transmission scheme for multiple unicast flows in a practical SIN downlink scenario. Then the mean number of NCed-HARQ transmission rounds is derived. Moreover, a new representation and calculation method by using the Laplace transform for reliable data delivery in NCed-HARQ is also presented, where the derivation of throughput expressions is in a matrix exponential distribution form. Finally, we compare the throughput performance of our NCed-HARQ with NCed-ARQ scheme and HARQ transmission scheme. Simulation results show that our NCed-HARQ transmission scheme can enhance the throughput, especially in the high signal-to-noise region.\",\n \"Title: An Efficient Construction Method for Ultra-Reliable Finite Length Analog Fountain Codes\\nYear: 2018\\n\\nAbstract: Ultra-reliable low latency communication (URLLC) is defined by the the third generation partnership project (3GPP) for the fifth generation (5G) mobile systems. In order to realize the stringent requirements of ultra-high reliability and low latency, the data block length needs to be small. However, most of the state-of-art channel codes are designed and optimized for long block length. Analog fountain code (AFC) is a capacity-approaching self-adaptive code on wireless channels with linear encoding/decoding complexity. In this paper, we study the optimization of AFC in the finite length regime. We first analyze the effect of average degree on decoding performance of AFC in the finite length regime. Then, based on the characteristic of weight coefficient in AFC, we proposed a joint design of weight optimization (WO) progressive edge growth (PEG)-AFC algorithm to improve the decoding performance in the finite length regime, named PEG-AFC algorithm. Simulation results show that the proposed PEG-AFC algorithm can achieve lower bit error rate (BER) in a wide range of signal to noise ratio (SNR).\",\n \"Title: Recurrent Binary Embedding for GPU-Enabled Exhaustive Retrieval from Billion-Scale Semantic Vectors.\\nYear: 2018\\n\\nAbstract: Rapid advances in GPU hardware and multiple areas of Deep Learning open up a new opportunity for billion-scale information retrieval with exhaustive search. Building on top of the powerful concept of semantic learning, this paper proposes a Recurrent Binary Embedding (RBE) model that learns compact representations for real-time retrieval. The model has the unique ability to refine a base binary vector by progressively adding binary residual vectors to meet the desired accuracy. The refined vector enables efficient implementation of exhaustive similarity computation with bit-wise operations, followed by a near-lossless k-NN selection algorithm, also proposed in this paper. The proposed algorithms are integrated into an end-to-end multi-GPU system that retrieves thousands of top items from over a billion candidates in real-time. The RBE model and the retrieval system were evaluated with data from a major paid search engine. When measured against the state-of-the-art model for binary representation and the full precision model for semantic embedding, RBE significantly outperformed the former, and filled in over 80% of the AUC gap in-between. Experiments comparing with our production retrieval system also demonstrated superior performance. While the primary focus of this paper is to build RBE based on a particular class of semantic models, generalizing to other types is straightforward, as exemplified by two different models at the end of the paper.\",\n \"Title: Efficient Design of Polar Coded STTD Systems over Rician MIMO Channels\\nYear: 2017\\n\\nAbstract: In this paper, a polar coded space-time transmit diversity (STTD) scheme is proposed in order to improve the performance of MIMO system. In Rician fading MIMO channels, the corresponding polar coded STTD system can be equivalent to a single transmission channel for each polar code bit. Density evolutions for the polar coded STTD systems are proposed based on the analyses of the single transmission channel. The proposed density evolutions provide preferable guidance to construct polar codes for the polar coded STTD systems. Simulation results show that the BER performance of polar coded STTD system is significantly improved as the number of antennas increases. The proposed 2 x 2 polar coded STTD system can provide better FER performance than LDPC-based system under low and mid code rates.\",\n \"Title: Optimal Transmission Policy Based on POMDP over Ka-Band Channels in SINs\\nYear: 2017\\n\\nAbstract: The Ka-band channels can provide an appealing capacity for the future deep-space communications and space information networks (SINs). In this paper, the noise temperature of time-varying rain attenuation at Ka-band channels is modeled to two states Gilbert-Elliot channel, to capture the channel capacity that randomly ranging from good to bad state. An optimal transmission scheme based on Partially Observable Markov Decision Processes (POMDP) is proposed, and the key thresholds for selecting the optimal transmission method for space information networks (SIN) are derived. Simulation results show that our proposed scheme can effectively improve the throughput.\",\n \"Title: Performance Analysis of MIMO-HARQ Schemes in LTP for Space Information Networks\\nYear: 2017\\n\\nAbstract: Recently, with the development of Ka/Q/V mmWave band high throughput satellites (HTS) and space information networks (SIN), distributed/virtual multiple-input multiple-output (MIMO) over satellite have attracted considerable research interest. In this paper, we propose a novel performance analysis framework for MIMO with orthogonal space-time block coding (OSTBC) under Licklider transmission protocol (LTP) in upcoming SINs, that the closed-form expressions of the mean number of transmission rounds for reliable data delivery in automatic repeat request (ARQ) and hybrid-ARQ (HARQ) schemes is derived by using Laplace transform. Furthermore, we derive throughput expressions for lossless- and truncated-HARQ schemes, and investigate the data delivery delay in LTP over Rayleigh and Rician fading channels. We also verify the accuracy of our derived closed-form expressions of mean number of transmission rounds through the Monte Carlo simulations.\",\n \"Title: Design of Rateless Transmission Scheme Based on Punctured Polar Codes\\nYear: 2017\\n\\nAbstract: In this paper, a parallel concatenated punctured polar (PCPP) codes is designed to realise the rateless property of polar codes. First, an improved random puncturing pattern of polar codes is proposed to archive better performance than random puncturing. Then, the optimal initial code rate is analyzed for multiple PCPP code blocks transmission in slow fading channels, which the optimal initial code rate of each new PCPP code block is determined by the overhead of the previous successful decoded code block and each packet can be transmitted with encoding construct of a 2-level PCPP codes.\",\n \"Title: Intermediate Performance of Rateless Codes over Dying Erasure Channel\\nYear: 2017\\n\\nAbstract: In this paper, we propose a new rateless coding scheme for dying erasure channels with random channel lengths and time-varying packet error rates. Firstly, we propose a heuristic approach for suboptimal degree distributions based on AND-OR tree technique to achieve higher intermediate performance. Secondly, the optimal code length for the maximum average date delivery ratio is derived and analyzed. Simulation results demonstrate that our coding scheme outperforms existing conventional rateless codes with significantly better performance, which can be employed as a solution to the efficient large bulk transmission on dynamical and unreliable channels.\",\n \"Title: Bounds on the Finite-Length RaptorQ Codes Under Maximum Likelihood Decoding\\nYear: 2017\\n\\nAbstract: In this paper, we analysis the maximum likelihood (ML) decoding failure probability (DFP) of finite length RaptorQ codes with a high-order low density generator-matrix (LDGM) code as the pre-code. By investigating the rank of the product of two random coefficient matrices, we derive upper and lower bounds of DFP on the RaptorQ codes under ML decoding algorithm. Finally, we verify the accuracy of derived theoretical bounds through the Monte Carlo simulations with different degree distributions. The high accuracy bounds can be used to design near-optimum RaptorQ codes with short and moderate lengths.\",\n \"Title: Outage Performance of Cooperative Deep-Space Downlink with Backbone Relaying in SBINs\\nYear: 2017\\n\\nAbstract: In this paper, we investigate the performance of cooperative deep-space downlink with an amplify-and-forward (AF) backbone relaying in Space-based Information Networks (SBINs). In this SBINs communication scenario, we assume both the source-destination and relay-destination links undergo the shadowed-Rician fading, and the source-relay link follows the Rician fading distributions, respectively. Moreover, the effect of satellite perturbation of backbone relaying satellite is considered, and the maximum ratio combining is implemented at the terrestrial destination. Based on this setup, we first derive the approximate statistical distributions of signal-to-noise ratio of the system, then the closed-form expressions are obtained to efficiently evaluate the outage probability (OP) of the system. Finally, some simulation results are provided to verify our analysis.\",\n \"Title: Rateless Coding Scheme Based on Autoregressive-Moving-Average Model over Ka-Band Links\\nYear: 2017\\n\\nAbstract: Future deep space explorations and spatial information networks (SINs) are with the increasing demands for high data rate services, the application of Ka-band channel is viewed as a primary solution. However, the Ka-band channel is much more sensitive to the weather conditions than S/C/X-band channels. In this paper, the noise temperature on Ka-band channel is modeled as N-states Markov channel, and a practical time-varying rain attenuation prediction model is proposed based on the Autoregressive-Moving-Average (ARMA) model. By considering the tradeoffs between transmission latency, reliability and power allocations consumptions, we design an adaptive rateless coding scheme based on the analog fountain codes. Simulation results show that our proposed scheme can effectively improve the throughput and efficiency.\",\n \"Title: Learning to Match Using Siamese Network for Object Tracking.\\nYear: 2018\\n\\nAbstract: The general object tracking problem traditionally been tackled by modeling the object's appearance. In this paper we consider object tracking as a similarity measurement problem. We focus on learning a matching mechanism with great generalization ability. We present a Siamese convolutional neural network as a matching function to perform object tracking. First we simply match the exemplary target in previous frame with the candidates in a new frame using cosine similarity and return the most similar one by the learnt matching function. Then we perform bounding box regression to refine the target position given by the network as the final result. Extensive experiments on real-world benchmark datasets validate the superior performance of our approach.\",\n \"Title: XML-based modeling method of phased-mission systems subject to probabilistic common cause failures.\\nYear: 2019\\n\\nAbstract: With the increasing of system scale and the growing of functional requirements and interactions within and/or among system hierarchies, there are more difficulties for safety engineers to carry out their works. Especially, the research on phased mission system (PMS) with probabilistic common cause failures (PCCFs) is still in the initial stage and has a lot of limitations, because the current researches have not yet considered the dynamic characteristics of PMSs. In this paper, a modular method is proposed as the theoretical basis to construct the components model in the PMS with PCCF. The relationships between common cause events were discussed and the probabilistic model of CCFs is extended, so that the model can fit for different statistical relations, and a module-based modeling and analysis method using binary decision diagram (BDD) and Markov model were proposed to deal with static and dynamic module in PMS respectively. Moreover, a standardization of description method for modular method using extensible markup language (XML) is given, based on which the system reliability model can be constructed by computer aided. Finally, the proposed method is demonstrated through a case study.\",\n \"Title: A Three-Hierarchy Evaluation of Polarimetric Performance of GF-3, Compared with ALOS-2/PALSAR-2 and RADARSAT-2.\\nYear: 2019\\n\\nAbstract: GaoFen-3 (GF-3) is the first Chinese civilian multi-polarization synthetic aperture radar (SAR) satellite, launched on 10 August of 2016, and put into operation at the end of January 2017. The polarimetric SAR (PolSAR) system of GF-3 is able to provide quad-polarization (quad-pol) images in a variety of geophysical research and applications. However, this ability increases the complexity of maintaining image quality and calibration. As a result, to evaluate the quality of polarimetric data, polarimetric signatures are necessary to guarantee accuracy. Compared with some other operational space-borne PolSAR systems, such as ALOS-2/PALSAR-2 (ALOS-2) and RADARSAT-2, GF-3 has less reported calibration and image quality files, forcing users to validate the quality of polarimetric imagery of GF-3 before quantitative applications. In this study, without the validation data obtained from a calibration infrastructure, an innovative, three-hierarchy strategy was proposed to assess PolSAR data quality, in which the performance of GF-3 data was evaluated with ALOS-2 and RADARSAT-2 data as references. Experimental results suggested that: (1) PolSAR data of GF-3 satisfied backscatter reciprocity, similar with that of RADARSAT-2; (2) most of the GF-3 PolSAR images had no signs of polarimetric distortion affecting decomposition, and the system of GF-3 may have been improved around May 2017; and (3) the classification accuracy of GF-3 varied from 75.0% to 91.4% because of changing image-acquiring situations. In conclusion, the proposed three-hierarchy approach has the ability to evaluate polarimetric performance. It proved that the residual polarimetric distortion of calibrated GF-3 PolSAR data remained at an insignificant level, with reference to that of ALOS-2 and RADARSAT-2, and imposed no significant impact on the polarimetric decomposition components and classification accuracy.\",\n \"Title: ARM: Adaptive Random-Selected Multi-Beamforming Estimation Scheme for Satellite-Based Internet of Things.\\nYear: 2019\\n\\nAbstract: In this paper, we focus on the millimeter-wave (mmWave) band multiple-input and multiple-output (MIMO) channel estimation in the satellite-based Internet of Things (S-IoT). At first, we establish a sparse geometric-based mmWave MIMO channel model between a high throughput satellite (HTS) and multiple terrestrial user equipments (UEs) for the S-IoT downlink system. By exploiting the sparsity inherent to themmWave band channel, we propose an efficient adaptive random-selected multi-beamforming (ARM) estimation scheme, which can simultaneously estimate themmWave MIMO channel state information (CSI) for multiple UEs in angle domain. The ARM estimation scheme measures of the CSI between the HTS and multiple UEs by utilizing a series of random combinations of transmitting beamforming vectors and receiving UEs' antennas and the required number of measurements can adaptively reduce as well as the signal-to-noise ratios (SNR) increases. To further improve the performance of ARM estimation scheme, the number of each beamforming been selected for the channel measurement is buffered, and modify the probability of the random selection of beams and UEs. Two improved ARM estimation schemes are proposed, one is ARM forcing adaptation beam selection (ARM-FABS) scheme, and the other is ARM partially estimated beam selection (ARM-PEBS) scheme. The simulation results show that the proposed ARM estimation schemes can reduce the required number of measurements and achieve a better tracking performance over a wide range of SNRs.\",\n \"Title: Deep Learning-Based Long-Term Power Allocation Scheme for NOMA Downlink System in S-IoT.\\nYear: 2019\\n\\nAbstract: In this paper, we formulate a long-term resource allocation problem of non-orthogonal multiple access (NOMA) downlink system for the satellite-based Internet of Things (S-IoT) to achieve the optimal decoding order and power allocation. This long-term resource allocation problem of the satellite NOMA downlink system can be decomposed into two subproblems, i.e., a rate control subproblem and a power allocation subproblem. The latter is a non-convex problem and the solution of which relies on both queue state and channel state. However, the queue state and the channel state continually change from one time slot to another, which makes it extremely strenuous to characterize the optimal decoding order of successive interference cancellation (SIC). Therefore, we explore the weight relationship between the queue state and the channel state to derive an optimal decoding order by leveraging deep learning. The proposed deep learning-based long-term power allocation (DL-PA) scheme can efficiently derive a more accurate decoding order than the conventional solution. The simulation results show that the DL-PA scheme can improve the performance of the S-IoT NOMA downlink system, in terms of long-term network utility, average arriving rate, and queuing delay.\",\n \"Title: Joint Power Allocation and Rate Control for NOMA-based Space Information Networks\\nYear: 2019\\n\\nAbstract: In this paper, we propose a novel power allocation scheme of downlink non-orthogonal multiple access (NOMA) system for space information networks (SINS). Since the communication resources such as power and storage on satellites are limited, we focus on an optimization policy of long-term resource allocation to meet these practical constraints. To address this problem, we convert the long-term optimization problem into a series of online power allocation and rate control problems by leveraging the Lyapunov optimization framework. Then, we employ the particle swarm optimization (PSO) algorithm to derive a globally optimal solution for this joint optimization problem, with a linear computational complexity. Simulation results show that the proposed joint optimization allocation NOMA scheme for SIN can outperform OMA and multiple sub-optimal NOMA benchmark schemes, in terms of long-term network utility, average arriving rate and queuing delay.\",\n \"Title: Optimized Puncturing for the Spinal Codes\\nYear: 2019\\n\\nAbstract: As a type of newly invented rateless codes, Spinal codes can achieve the capacity of both additive white Gaussian noise (AWGN) channel and binary symmetric channel (BSC) with short message length and pseudo-random like codewords. In this paper, a novel puncturing pattern called inverted triangle-shaped puncturing is proposed for Spinal codes. We prove a lemma as theoretical support for the proposed inverted triangle-shaped puncturing. Compared with the uniform puncturing pattern, Spinal codes can be punctured to achieve both high and finer-grained rates by the inverted triangle-shaped puncturing, without increasing the cost of decoding. Extensive simulations are carried out to verify the effectiveness of the proposed pattern. Results show that the inverted triangle-shaped puncturing pattern can increase the code rate significantly without any harming to the bit error rate (BER) performance.\",\n \"Title: GalaXC: Graph Neural Networks with Labelwise Attention for Extreme Classification\\nYear: 2021\\n\\nAbstract: ABSTRACT This paper develops the GalaXC algorithm for Extreme Classification, where the task is to annotate a document with the most relevant subset of labels from an extremely large label set. Extreme classification has been successfully applied to several real world web-scale applications such as web search, product recommendation, query rewriting, etc. GalaXC identifies two critical deficiencies in leading extreme classification algorithms. First, existing approaches generally assume that documents and labels reside in disjoint sets, even though in several applications, labels and documents cohabit the same space. Second, several approaches, albeit scalable, do not utilize various forms of metadata offered by applications, such as label text and label correlations. To remedy these, GalaXC presents a framework that enables collaborative learning over joint document-label graphs at massive scales, in a way that naturally allows various auxiliary sources of information, including label metadata, to be incorporated. GalaXC also introduces a novel label-wise attention mechanism to meld high-capacity extreme classifiers with its framework. An efficient end-to-end implementation of GalaXC is presented that could be trained on a dataset with 50M labels and 97M training documents in less than 100 hours on 4 × V100 GPUs. This allowed GalaXC to not only scale to applications with several millions of labels, but also be up to 18% more accurate than leading deep extreme classifiers, while being upto 2-50 × faster to train and 10 × faster to predict on benchmark datasets. GalaXC is particularly well-suited to warm-start scenarios where predictions need to be made on data points with partially revealed label sets, and was found to be up to 25% more accurate than extreme classification algorithms specifically designed for warm start settings. In A/B tests conducted on the Bing search engine, GalaXC could improve the Click Yield (CY) and coverage by 1.52% and 1.11% respectively. Code for GalaXC is available at https://github.com/Extreme-classification/GalaXC\",\n \"Title: An Adaptive Decomposition Approach With Dipole Aggregation Model For Polarimetric Sar Data\\nYear: 2021\\n\\nAbstract: Polarimetric synthetic aperture radar (PolSAR) has attracted lots of attention from remote sensing scientists because of its various advantages, e.g., all-weather, all-time, penetrating capability, and multi-polarimetry. The three-component scattering model proposed by Freeman and Durden (FDD) has bridged the data and observed target with physical scattering model, whose simplicity and practicality have advanced remote sensing applications. However, the three-component scattering model also has some disadvantages, such as negative powers and a scattering model unfitted to observed target, which can be improved by adaptive methods. In this paper, we propose a novel adaptive decomposition approach in which we established a dipole aggregation model to fit every pixel in PolSAR image to an independent volume scattering mechanism, resulting in a reduction of negative powers and an improved adaptive capability of decomposition models. Compared with existing adaptive methods, the proposed approach is fast because it does not utilize any time-consuming algorithm of iterative optimization, is simple because it does not complicate the original three-component scattering model, and is clear for each model being fitted to explicit physical meaning, i.e., the determined adaptive parameter responds to the scattering mechanism of observed target. The simulation results indicated that this novel approach reduced the possibility of the occurrence of negative powers. The experiments on ALOS-2 and RADARSAT-2 PolSAR images showed that the increasing of adaptive parameter reflected more effective scatterers aggregating at the 45 degrees direction corresponding to high cross-polarized property, which always appeared in the 45 degrees oriented buildings. Moreover, the random volume scattering model used in the FDD could be expressed by the novel dipole aggregation model with an adaptive parameter equal to one that always appeared in the forest area.\",\n \"Title: Age-optimal Transmission Policy for Intelligent HARQ-CC aided NOMA Systems\\nYear: 2021\\n\\nAbstract: This paper investigates the timeliness performance of a downlink wireless communication system with a base station (BS) serving two users under the non-orthogonal multiple access (NOMA) system. The hybrid automatic repeat request with chase combining (HARQ-CC) in finite blocklength is considered. For minimizing the information freshness which is characterized by Age of Information (AoI), an intelligent system is adopted. The BS can adjust the power allocation to each user in NOMA, and decide to transmit old or new packets to each user, according to the users' current AoI status and the positive/negative acknowledgement (ACK/NACK) feedback signal. First, the closed-form of the individual user's outage probability with arbitrary power allocation combination of HARQ-CC aided NOMA system is derived. Based on the outage probability, the optimization of the system average AoI is achieved by minimizing the Lyapunov Drift function of each time slot. By introducing the HARQ-CC mechanism into the NOMA scheme, a trade-off between reliability and timeliness can be achieved, which is found that this policy can improve the AoI performance of NOMA scheme in low signal-noise ratio (SNR) and outperform existing works on NOMA and orthogonal multiple access (OMA).\",\n \"Title: Age-optimal Power Allocation Policies for NOMA and Hybrid NOMA/OMA Systems\\nYear: 2021\\n\\nAbstract: In this paper, we study downlink short-packet communication in wireless networks, where a base station (BS) sends time-sensitive status updates to users via non-orthogonal multiple access (NOMA) or Adaptive NOMA/orthogonal multiple access (OMA). The Age of Information (AoI), namely the amount of time that elapsed since the most recently delivered packet was generated, captures the freshness of the information. We aim to minimize the Expected Weighted Sum AoI (EWSAoI) by optimizing the power allocation. First, a low-complexity power allocation policy, namely Stationary Power Allocation policy is proposed in NOMA. In this policy, the BS allocates fixed power to each user and we obtain the closed-form expression of the optimal allocation factor to minimize the EWSAoI. Then, we propose an Adaptive NOMA/OMA policy based on Lyapunov Optimization in which the BS can adaptively switch between NOMA and OMA and dynamically allocate power for users to keep the EWSAoI low. Numerical results demonstrate the advantages of the proposed policies, which provide useful insights for practical system designs.\",\n \"Title: Age-Optimal Power Allocation Scheme for NOMA-based S-IoT Downlink Network\\nYear: 2021\\n\\nAbstract: In this paper, we consider a non-orthogonal multiple access (NOMA)-based satellite-integrated internet of things (S-IoT) network, where a satellite transmits timely status updates to multiple user equipments (UEs). To keep the freshness of status updates in this network, we formulate an age of information (AoI) optimization problem subject to long/short-term power and throughput constraints. We leverage tools from Lyapunov optimization to transform the optimization problem into a sequence of online power allocation problems. Since the original optimization problem is non-convex and hard to find the optimal solution, we utilize the particle swarm optimization (PSO) algorithm to obtain an optimal solution within a linear computational complexity. Simulation results show that our proposed NOMA-AoI scheme outperforms the benchmark schemes with regard to AoI performance. Furthermore, we also discuss the impact of importance weight V on the AoI and power consumption and validate the tradeoff.\",\n \"Title: Efficient Ordered Statistics Decoder for Ultra-Reliable Low Latency Communications\\nYear: 2021\\n\\nAbstract: Short length channel coding and low complexity decoding is essential for 5G ultra-reliable low latency communications (uRLLC). In this paper, au efficient ordered statistics decoder (E-OSD) scheme is proposed for finite length non-binary Raptor code (NBRC) towards uRLLC. The segmentation and discarding rules of test error patterns, and the stop criteria are designed for the proposed E-OSD scheme to reduce the decoding complexity. A block error rate (BLER) upper bound of the NBRC under OSD is derived to estimate the number of NBRC symbols required for achieving the desired BLER performance. Simulation results show that the complexity of the proposed E-OSD scheme is greatly reduced compared to the existing OSD schemes, and it can achieve the BLER lower than 10(-5) in the finite length regime (<256 bits), satisfying the requirements of uRLLC.\",\n \"Title: Random Access with and without Sensing in Non-Terrestrial Networks for Timely Updates\\nYear: 2021\\n\\nAbstract: The growing boom in time-critical applications such as remote sensing and monitoring has made low latency of information an important requirement. Age of information (AoI) has been proposed to measure the freshness of information from the receiver side. In this paper, we analyze that multiple sources transmit their status packets to a remote controller for timely updates. Characterized by long transmission distances, satellite networks are commonly using Aloha as a random access protocol by preconceiving channel sensing is low efficient. Yet, for some non-terrestrial networks where the propagation delay is comparable to the transmission time, the performance comparison between Aloha and CSMA requires more detailed consideration. By building the node-centric discrete-time Markov chain, we quantify the performance of Aloha and CSMA on AoI and give the performance break-even point. Only when the ratio of propagation delay to transmission time is larger than this point, Aloha performs better on the timeliness metric. Furthermore, we derive the optimal attempt probability of CSMA to achieve the lowest latency. In the end, simulation results confirmed the validity of the theoretical analysis.\",\n \"Title: Scheduling Strategy Design Framework For Cyber-Physical System With Non-Negligible Propagation Delay\\nYear: 2021\\n\\nAbstract: Cyber-physical systems (CPS) have been widely employed as wireless control networks. There is a special type of CPS which is developed from the wireless networked control systems (WNCS). They usually include two communication links: Uplink transmission and downlink transmission. Those two links form a closed-loop. When such CPS are deployed for time-sensitive applications such as remote control, the uplink and downlink propagation delay are non-negligible. However, existing studies on CPS/WNCS usually ignore the propagation delay of the uplink and downlink channels. In order to achieve the best balance between uplink and downlink transmissions under such circumstances, we propose a heuristic framework to obtain the optimal scheduling strategy that can minimize the long-term average control cost. We model the optimization problem as a Markov decision process (MDP), and then give the sufficient conditions for the existence of the optimal scheduling strategy. We propose the semi-predictive framework to eliminate the impact of the coupling characteristic between the uplink and downlink data packets. Then we obtain the lookup table-based optimal offline strategy and the neural network-based suboptimal online strategy. Numerical simulation shows that the scheduling strategies obtained by this framework can bring significant performance improvements over the existing strategies.\",\n \"Title: MSPA: Multislot Pilot Allocation Random Access Protocol for mMTC-Enabled IoT System\\nYear: 2021\\n\\nAbstract: To provide massive connectivity in massive machine-type communications (mMTCs) for the Internet of Things (IoT) system, a novel grant free random access protocol, called multislot pilot allocation (MSPA) is proposed in this article, where the user equipments (UEs) are permitted to jointly transmit randomly chosen pilot sequences along with their data packets over multislot to resolve intracell pil...\",\n \"Title: An Age Optimized Hybrid ARQ Scheme for Polar Codes via Gaussian Approximation\\nYear: 2021\\n\\nAbstract: In this letter, we take the lead in investigating the average AoI performance for polar coded status updates over the additive white Gaussian noise (AWGN) channels. Compared with the non-automatic repeat request (non-ARQ) scheme, the hybrid ARQ with chase combining (HARQ-CC) scheme can effectively reduce the average AoI, especially in the low signal-to-noise ratio (SNR) region. Then, to improve th...\",\n \"Title: Taming Sparsely Activated Transformer with Stochastic Experts.\\nYear: 2022\\n\\nAbstract: Sparsely activated models (SAMs), such as Mixture-of-Experts (MoE), can easily scale to have outrageously large amounts of parameters without significant increase in computational cost. However, SAMs are reported to be parameter inefficient such that larger models do not always lead to better performance. While most on-going research focuses on improving SAMs models by exploring methods of routing inputs to experts, our analysis reveals that such research might not lead to the solution we expect, i.e., the commonly-used routing methods based on gating mechanisms do not work better than randomly routing inputs to experts. In this paper, we propose a new expert-based model, THOR (Transformer witH StOchastic ExpeRts). Unlike classic expert-based models, such as the Switch Transformer, experts in THOR are randomly activated for each input during training and inference. THOR models are trained using a consistency regularized loss, where experts learn not only from training data but also from other experts as teachers, such that all the experts make consistent predictions. We validate the effectiveness of THOR on machine translation tasks. Results show that THOR models are more parameter efficient in that they significantly outperform the Transformer and MoE models across various settings. For example, in multilingual translation, THOR outperforms the Switch Transformer by 2 BLEU scores, and obtains the same BLEU score as that of a state-of-the-art MoE model that is 18 times larger. Our code is publicly available at: github.com/microsoft/Stochastic-Mixture-of-Experts.\",\n \"Title: Massive Access in Space-Based Internet of Things: Challenges, Opportunities, and Future Directions\\nYear: 2021\\n\\nAbstract: The integration of fifth generation (5G) mobile network and satellite communication promises a promotion on the interconnection of everything, and has become one of the key development directions of beyond 5G and even 6G. As an inevitable development trend of mobile communication, the space-based Internet of Things (S-IoT) is expected to be commercially available in building an integrated informat...\",\n \"Title: Adjustable Ordered Statistic Decoder for Short Block Length Code towards URLLC\\nYear: 2021\\n\\nAbstract: The fifth generation (5G) ultra-reliable low latency communications (uRLLC) needs short block length codes to ensure the low latency requirement, which also brings the challenge in the design of maximum likelihood decoder (MLD) with practical complexity. In this paper, an adjustable-ordered statistics decoder (OSD) algorithm is proposed for short block length code to achieve the MLD performance wi...\",\n \"Title: Spinal Codes Over Fading Channel: Error Probability Analysis and Encoding Structure Improvement\\nYear: 2021\\n\\nAbstract: In order to facilitate the reliability of data transmission of Spinal codes over the fading channel, performance analysis of Spinal codes is conducted, and an improved encoding structure is proposed. First, we derive an approximate frame error rate (FER) upper bound for Spinal codes over the Rayleigh fading channel in the finite block length (FBL) regime. Then, inspired by the FER analysis process...\",\n \"Title: Freshness-Critical Transmission Scheme with IR-HARQ over Multi-Hop Satellite-IoT\\nYear: 2021\\n\\nAbstract: With the development of low earth orbits (LEO) high throughput satellite (HTS), satellite-Internet of Things (S-IoT) has become a crucial direction in beyond 5G (B5G) and future sixth generation (6G) mobile system due to the ubiquitous coverage and broadband access capability inherited from the HTS. Several S-IoT applications for monitoring status updates can be seen as classic cases of real time transmission, where the main performance parameters are the information freshness and fairness of the network, i.e., the age of information (AoI) and Jain's Fairness Index (JFI), respectively. In this paper, we propose a freshness-critical incremental-redundancy hybrid automatic repeat request (FCIR-HARQ) multi-hop transmission scheme to improve the AoI and JFI performance, where each hop adopts the Last Come First Serve with preemption only in waiting (LCFS-W) policy with a buffer only store the latest file. In particular, we derive the closed form expression of average AoI (AAoI) in the above multi-hop S-IoT, and analyze the corresponding JFI in each hop. Simulation results validate the accuracy of our derivations, and show that the proposed FCIR-HARQ multi-hop transmission scheme with LCFS- W policy outperforms the existing First Come First Serve (FCFS) policy in terms of AAoI.\",\n \"Title: Age-Critical Blockchain Resource Allocation over Satellite-based Internet of Things\\nYear: 2021\\n\\nAbstract: With the development of next generation of mobile communications, the access of massive Internet of Things (IoT) devices need a more intelligent and secure network. Blockchain has become an emerging technology due to its characteristics of decentralization, stability and transparency. Thus, the combination of blockchain and IoT has attracted the focus of researches. However, the conventional blockchain based on terrestrial network are limited to the scalability and latency. With the support of the wide coverage of satellite, satellite-based Internet of Things (S-IoT) can solve the defect of large consensus latency of blockchain in terrestrial networks. In this paper, considering the limitation of system power and to improve the freshness of information, i.e., the age of information (AoI), we propose a power allocation scheme to accelerate the blockchain consensus over the S-IoT network. Then, we derive the closed-form expressions to the latency and power consumption of blockchain consensus over the S-IoT network. Moreover, we formulate an average AoI (AAoI) optimization problem subject to the total power constraints and solve it by genetic algorithm. Simulation results show that the proposed power allocation scheme has a superior performance in terms of AAoI and throughput compared to the conventional blockchain schemes.\",\n \"Title: Age-Critical Frameless ALOHA Protocol for Grant-Free Massive Access\\nYear: 2021\\n\\nAbstract: In this paper, we analyze the freshness of information in grant-free massive access via a new metrics named age of information (AoI), and propose an age-critical frameless ALOHA (ACFA) random access protocol, where the average AoI (AAoI) is implicitly reduced by banning the transmission of activated user equipments (UEs) recovery successful in the last frame. In particular, in order to analyze the AAoI performance of the ACFA random access protocol, we define two metrics named the average channel load and packets recovery rate (PRR) of ACFA protocol, and tracking the evolution of the number of access-allowed UEs in each frame. Then we derive an analytical expression of AAoI as a function of the frame length and the PRR in the ACFA random access protocol. Simulation results validate the accuracy of our theoretical analysis and show the great potential of ACFA random access protocol in minimizing AAoI.\",\n \"Title: Age-Critical Pilot Allocation Random Access Protocol for Space-Air-Ground Integrated Networks\\nYear: 2021\\n\\nAbstract: Due to ubiquitous coverage inherited from the satellites, space-air-ground integrated networks (SAGIN) has been viewed as a promising enabler to provide \\\"anywhere and anytime\\\" broadband access for the next generation of mobile network. Nevertheless, the status updating to the satellite of terrestrial sensing devices could be hindered by the propagation delay. As a result, it becomes crucial to investigate the timeliness of information for massive machine type communications (mMTC) random access in SAGIN. In this paper, we analyse the timeliness of information for the mMTC random access scenario via a new performance metric named age of information (AoI), and propose an age-critical pilot allocation (ACPA) random access protocol aiming to lower the system average Aol (AAoI). By tracking the Aol evolution of each device via Markovian analysis, the closed-form expression of the system AAoI is derived, then we conduct an optimal number of slots to achieve the lowest system AAoI with the increasing of the system load. Simulation results validate the accuracy of our theoretical analysis, and also show that our ACPA protocol can significantly outperform other relevant random access protocols in terms of reducing the AAoI in overload cases.\",\n \"Title: Self-Adaptive Ordered Statistics Decoder for Finite Block Length Raptor Codes Toward URLLC\\nYear: 2022\\n\\nAbstract: Rateless codes can adapt to the wireless channel conditions without accurate channel state information (CSI) at the transmitter side, avoiding CSI feedback and retransmission, and thus are a promising channel coding approach to meet the stringent requirements of ultrareliable low-latency communications (uRLLCs). This article investigates a self-adaptive ordered statistics decoder (S-OSD) scheme fo...\",\n \"Title: CS-LTP-Spinal: a cross-layer optimized rate-adaptive image transmission system for deep-space exploration\\nYear: 2022\\n\\nAbstract: Reliable and efficient image transmission is crucial for deep-space exploration. However, the extremely long distance and complex deep-space environment introduce severe design and implementation challenges. In this work, we propose a novel high-efficiency system, CS-LTP-Spinal, to address the challenges encountered in deep-space image transmission. CS-LTP-Spinal is designed to work over the Licklider transmission protocol (LTP) of the delay-tolerant network (DTN). By incorporating compressed sensing (CS) and the Spinal codes as the application and physical layer techniques, CS-LTP-Spinal can satisfy the constraints originating from resource asymmetry between the space vehicles and the ground station. To match the time-varying deep-space channels, two coarse-grained rate-adaptive transmission strategies are designed that employ different CS decompression mechanisms based on erasure-tolerant and error-tolerant decompression, respectively, to exploit the robustness of CS reconstruction to erasures and errors. Then, the rates of CS compression and Spinal coding are optimized over the application, transport, and physical layers. A semi-physical deep-space communication platform is built, and extensive simulations on the Mars-to-Earth scenario are conducted. The results demonstrate that the designed CS-LTP-Spinal system with cross-layer optimized rate-adaptive transmission strategies has significant performance advantages over its counterparts by achieving near-ideal image transmission efficiency.\",\n \"Title: Real-Time Aeromagnetic Compensation With Compressed and Accelerated Neural Networks\\nYear: 2022\\n\\nAbstract: As neural networks become an increasingly popular technique in the field of aeromagnetic compensation, there is an increasing demand for hardware systems with more computing power. Compared with the linear regression method, applying a neural network to the task of real-time compensation is difficult because of insufficient computing resources in the unmanned aerial vehicle (UAV) flight detection platform. To perform real-time compensation calculations with limited computing resources, we optimized back propagation neural network (OBPNN) through model compression and acceleration. In this study, we found that the most time-consuming part of network training is the iterative updating of the weights in the BPNN interference model. Using transfer learning, we replace the randomly initialized weights (RWs) with pretrained weights, thereby greatly reducing the number of iterations required. We also apply other model compression and acceleration algorithms. In a case study of our new technique, we implement the fast training of the OBPNN on a Raspberry Pi 4B system. This network processes approximately 316 samples per 0.1 s, which is fast enough to complete aeromagnetic compensation in real time.\",\n \"Title: On the Prediction Policy for Timely Status Updates in Space-Air-Ground Integrated Transportation Systems\\nYear: 2022\\n\\nAbstract: In this paper, we investigate the timeliness of the vehicular status updates in space-air-ground integrated networks (SAGIN) for intelligent transportation systems (ITS). The Age of Information (AoI) is introduced to capture the timeliness of the vehicular status updates. To overcome the inherent end-to-end latency taken by the long-distance communications in SAGIN for ITS, prediction has attracte...\",\n \"Title: Tradeoff Optimization Technology of Effectiveness-Cost for Satellite-Based on CAIV Method\\nYear: 2022\\n\\nAbstract: The tradeoff of effectiveness and cost is a vital problem for complex industrial systems, mainly applied in the weapons and aviation fields. As a typical complex industrial system, the effectiveness-cost tradeoff of the satellites becomes challenging and interesting. This paper takes a remote sensing satellite as a research object, and an integrated approach to assess and optimize its effectiveness and cost is proposed. The characteristic parameters are selected according to an analysis of its structure and mission. Furthermore, the effectiveness evaluation model is established based on the Availability-Dependability-Capability (ADC) model, and the cost parameter model is developed using historical data and regression analysis. According to the Cost as Independent Variable (CAIV) method, the objective function of the satellite effectiveness-cost with the effectiveness-cost tradeoff space is established. The objective function is solved and optimized using a genetic algorithm to achieve a more efficient and economical satellite design scheme.\",\n \"Title: Grant Free Age-Optimal Random Access Protocol for Satellite-Based Internet of Things\\nYear: 2022\\n\\nAbstract: In satellite-based Internet of Things (S-IoT) system, the timely status updating of terrestrial sensing user equipments (UEs) to satellite could be hampered by the long propagation delay, especially in massive machine type communications (mMTC). To guarantee the information freshness in S-IoT, a new performance indicator called age of information (AoI) is exploited to analyze the average AoI (AAoI) in the overload case of mMTC, and a grant free age-optimal (GFAO) random access protocol is proposed to lower the AAoI. Specifically, the closed-form expression of AAoI is derived by tracing the instantaneous AoI evolution of each UE through Markov analysis. Then, the proposed GFAO random access protocol is proved to achieve a minimum AAoI and a maximum throughput in S-IoT, by adjusting the number of access time slots in each transmission frame in the overload case of mMTC. Extensive simulations are conducted to validate the theoretical analysis, and show that there exists different optimal value of access time slots in system load region from 0.2 to 3, which can minimize AAoI and maximize throughput in the proposed GFAO random access protocol.\",\n \"Title: On Scheduling Policy for Multi-process Cyber-Physical System with Edge Computing\\nYear: 2022\\n\\nAbstract: In this paper, we consider a cyber-physical system (CPS) with multiple Internet of Things (IoT) devices. There are multiple independent linear time-invariant processes in the system, which are sampled by sensors, scheduled by controllers and controlled by actuators. In the literature of wireless control CPS, commonly assume that the system just have one controller and ignore the processing time on server. In this work we employ the edge computing, the controllers are facilitated by edge server and cloud server. The processing time of status update depends on the characteristic of different processes and servers. By taking into account such conditions, we mainly investigate how to choose the destination of status updates (i.e., edge server or cloud server) to minimize the average Mean Square Error (MSE) of the entire system. To address this issue, we formulate a Markov Decision Process (MDP) problem and obtain the optimal scheduling policy. The threshold property of the optimal scheduling policy is proved, and a suboptimal policy is proposed to overcome the curse of dimensionality. The simulation results illustrate that the selection of controller is related to the timeliness of process and show the superiority of the proposed policies.\",\n \"Title: Partial Self-Concatenation Structure and Performance Analysis of Spinal Codes Over Rayleigh Fading Channel\\nYear: 2022\\n\\nAbstract: Spinal codes are a new family of rateless codes which have been proved to be capacity-achieving over both the additive white Gaussian noise (AWGN) channel and the binary symmetric channel (BSC). However, over the Rayleigh fading channel between the vehicle nodes, the error performance of Spinal codes is not satisfactory since the tail message blocks of Spinal codes are prone to error. To solve this issue, this paper proposes a new practical partial self-concatenation coding structure of Spinal codes, named \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$N$</tex-math></inline-formula>\\n tail-protected Spinal codes, to pointedly protect tail message blocks of Spinal codes over the flat Rayleigh fading channel. Theoretical performance analysis and simulation results are also provided to validate and verify the effectiveness of the proposed \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$N$</tex-math></inline-formula>\\n tail-protected Spinal codes.\",\n \"Title: Short Analog Fountain Code With Quasi-Gray Constellation Mapping Modulation Towards uRLLC\\nYear: 2022\\n\\nAbstract: In this paper, a capacity-approaching rateless coded modulation towards ultra-reliable low latency communications (uRLLC) is proposed, including the joint design of short block-length analog fountain code (AFC) and quasi-gray constellation mapping (QGCM) modulation at the transmitter, and a limited feedback mechanism for the receiver. First, based on the nonlinear constellation and quasi-gray mapping, we design a novel rateless coded modulation scheme called AFC-QGCM, and prove it can approach to the Shannon capacity. Further, the theoretical evaluation framework of information density between the achievable rate and signal-to-noise (SNR) of the AFC-QGCM schemes is derived under short block-length. Based on the analysis, we propose a rateless transmission scheme with a limited feedback link over the fading channel without precise channel state information (CSI) at the transmitter, which could utilize the theoretical analysis to determine the optimal coding and modulation parameters during the transmission. Both analysis and simulation results shown that the proposed scheme could approaching to the Polyanskiy-Poor-Verdu (PPV) meta converse benchmark in a wide range SNRs.\",\n \"Title: Age-Oriented Transmission Protocol Design in Space-Air-Ground Integrated Networks\\nYear: 2022\\n\\nAbstract: In this paper, we study the age-oriented hybrid automatic repeat request (HARQ) protocol design in space-air-ground integrated networks (SAGINs) scenarios. A real-time communication system, where the updates are delivered from the remote nodes to terrestrial devices, is formulated. As the end-to-end latency \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$D$ </tex-math></inline-formula>\\n is nontrivial, the traditional HARQ with frequent feedbacks is not always beneficial to timely transmission. Intuitively, there is a threshold \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$D^{*}$ </tex-math></inline-formula>\\n of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$D$ </tex-math></inline-formula>\\n, only within which retransmission is advantageous to age. Inspired by this, we formulate an age-optimal redundancy allocation problem and derive the explicit expression of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$D^{*}$ </tex-math></inline-formula>\\n for advantageous retransmissions. Besides, to further increase the timeliness of the system, we propose a fast incremental redundancy hybrid ARQ protocol (fast IR-HARQ), where successive decoding and feedback operations are omitted based on channel estimation. Considering the shadowed Rician fading channel and finite blocklength regime, we derive expressions of the average age for the standard IR-HARQ and fast IR-HARQ setups. As expected, the proposed fast IR-HARQ scheme reduces the average age significantly compared with the IR-HARQ strategy. Further, we evaluate the influence of different parameters on the age performance of the fast IR-HARQ scheme. The results demonstrate the superiority of the proposed fast IR-HARQ protocol without loss of reliability.\",\n \"Title: A Weighted Graph-Based Handover Strategy for Aeronautical Traffic in LEO SatCom Networks\\nYear: 2022\\n\\nAbstract: With the development of space-air-ground integrated network (SAGIN), the Low Earth Orbit Satellite Communication (LEO SatCom) network has great potential to provide high rate communication services for aeronautical traffic. To overcome the frequency handovers between aircraft and LEO satellites, we generated a global aeronautical traffic demand map and utilized the graph-based handover (GBH) framework and the multi-attribute decision making (MADM) algorithm jointly to optimize the overall throughput. Moreover, we further propose a new parameter, called channel reservation order (CRO), for MADM algorithm. Simulation results indicate our strategy improves the performance in terms of overall throughput and access failure probability.\",\n \"Title: On Scheduling Policy for Multiprocess Cyber–Physical System With Edge Computing\\nYear: 2022\\n\\nAbstract: In this article, we consider a cyber–physical system (CPS) with multiple Internet of Things (IoT) devices. There are multiple independent linear time-invariant processes in the system, which are sampled by sensors, scheduled by controllers, and controlled by actuators. In the literature of wireless control CPS, commonly assume that the system just have one controller and ignore the processing time on server. In this work we employ the edge computing, the controllers are facilitated by edge server and cloud server. The processing time of status update depends on the characteristic of different servers and processes. By taking into account such conditions, we mainly investigate how to choose the destination of status updates (i.e., edge server or cloud server) to minimize the average mean square error (MSE) of the entire system. To address this issue, we formulate a Markov decision process (MDP) problem and obtain the optimal scheduling policy. The threshold property of the optimal scheduling policy is proved, and a suboptimal policy is proposed to overcome the curse of dimensionality. Furthermore, the processing preemption mechanism is considered to schedule the status updates more flexibly, and its consistency property is proved. The simulation results illustrate that the selection of controller is related to the timeliness of process and show the superiority of the proposed policies.\",\n \"Title: Analysis and Optimization of the HARQ-Based Spinal Coded Timely Status Update System\\nYear: 2022\\n\\nAbstract: The age of information (AoI) is a new metric to measure the timeliness of various status update systems, and hybrid automatic repeat request (HARQ) transmission scheme is usually applied to ensure higher timeliness. However, little research considers encoding delay, propagation delay, decoding delay and feedback delay in the HARQ-based coded status update system. To the best of our knowledge, in this paper, the HARQ-based Spinal coded timely status update system with all the practical delay elements is considered for the first time. We derive the average AoI expression of the system and analyze the monotony of the AoI expression to give an average AoI upper bound. Then we optimize the HARQ transmission scheme to minimize the AoI. To decrease the complexity of the optimization algorithm, we separate it into two steps. First, we optimize the puncturing pattern of Spinal codes and propose a transmission scheme under incremental tail transmission puncturing (ITTP) pattern. Second, we optimize the number of symbols in each round under the ITTP transmission scheme, and propose the optimal transmission scheme under the coarse-grained ITTP pattern. Simulation results show that the proposed transmission scheme can significantly decrease the AoI compared to the baseline transmission schemes.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":108,"string":"108"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":249,"string":"249"}}},{"rowIdx":250,"cells":{"question_id":{"kind":"string","value":"Marco Mattavelli"},"question":{"kind":"string","value":"Generate an abstract for the title \"Programming Models and Methods for Heterogeneous Parallel Embedded Systems\" using the following items: 1. Digital Signal Processing \n2. Higher-level programming models \n3. Dataflow programs \n4. Implementing and optimizing complex signal processing \n5. Heterogeneous and massive parallel embedded systems"},"answer":{"kind":"string","value":"The growing complexity of digital signal processing applications makes a compelling case for the adoption of higher-level programming models such as dataflow for the implementation of applications on programmable logic devices and many/multi-core embedded processors. Past research works have shown that raising the level of abstraction of design stages does not necessarily come at penalties in results in terms of performance or resource requirements. Dataflow programs provide a high-level behavioral descriptions capable of expressing both sequential and parallel components of application algorithms and enable natural design abstractions, modularity, and portability. This paper presents an overview of the main features, recent achievements and results of a design-flow, entirely dataflow based, and the associated tools capable of implementing and optimizing complex signal processing system applications on heterogeneous and massive parallel embedded systems."},"correct_answer":{"kind":"string","value":"The growing complexity of digital signal processing applications makes a compelling case for the adoption of higher-level programming models such as dataflow for the implementation of applications on programmable logic devices and many/multi-core embedded processors. Past research works have shown that raising the level of abstraction of design stages does not necessarily come at penalties in results in terms of performance or resource requirements. Dataflow programs provide a high-level behavioral descriptions capable of expressing both sequential and parallel components of application algorithms and enable natural design abstractions, modularity, and portability. This paper presents an overview of the main features, recent achievements and results of a design-flow, entirely dataflow based, and the associated tools capable of implementing and optimizing complex signal processing system applications on heterogeneous and massive parallel embedded systems."},"documents":{"kind":"list like","value":["Title: Algorithm/architecture co-exploration of visual computing on emergent platforms: overview and future prospects\nYear: 2009\n\nAbstract: Concurrently exploring both algorithmic and architectural optimizations is a new design paradigm. This survey paper addresses the latest research and future perspectives on the simultaneous development of video coding, processing, and computing algorithms with emerging platforms that have multiple cores and reconfigurable architecture. As the algorithms in forthcoming visual systems become increasingly complex, many applications must have different profiles with different levels of performance. Hence, with expectations that the visual experience in the future will become continuously better, it is critical that advanced platforms provide higher performance, better flexibility, and lower power consumption. To achieve these goals, algorithm and architecture co-design is significant for characterizing the algorithmic complexity used to optimize targeted architecture. This paper shows that seamless weaving of the development of previously autonomous visual computing algorithms and multicore or reconfigurable architectures will unavoidably become the leading trend in the future of video technology.","Title: A Parallel Multimedia Processor For Macroblock Based Compression Standards\nYear: 1997\n\nAbstract: This paper presents a multimedia processor based on a SIMD architecture optimized for block based video processing algorithms.The processor, called DGP (Digital Generic Processor), is a generic system architecture, constituted by an array of pixel processors (SIMD) and a RISC controller. It is able to execute various video processing algorithms such as digital filtering, video effects, window clipping, and to perform video compression according to standards such as H.261, H.263, MPEG-1 and MPEG-2. The processor can be programmed in order to run the code corresponding to each specific algorithm.","Title: Reconfigurable video coding: objectives and technologies\nYear: 2009\n\nAbstract: The main objective of the MPEG Reconfigurable Video Coding (RVC) standard is to establish a framework for a more flexible usage of standard video coding technology. The framework not only supports multiple standards and new coding configurations, but also provides an incremental and modular approach to innovation in video compression development and design. This paper provides an overview of the main objectives of RVC, standard accompanied with a presentation of the components of the framework for both normative parts and supporting tools useful for the final implementation of RVC codecs. These elements include: the Video Tool Library (VTL), the new standard RVC-CAL language used for the specification of the library, the Bitstream Syntax Description (BSD) used for the specification of the compressed bitstreams, as well as the Functional unit Network Description (FND) that constitutes the specification of a modular library. Technologies and tools that support the RVC standard are also briefly introduced.","Title: Hardware and software synthesis of heterogeneous systems from dataflow programs\nYear: 2012\n\nAbstract: The new generation of multicore processors and reconfigurable hardware platforms provides a dramatic increase of the available parallelism and processing capabilities. However, one obstacle for exploiting all the promises of such platforms is deeply rooted in sequential thinking. The sequential programming model does not naturally expose potential parallelism that effectively permits to build parallel applications that can be efficiently mapped on different kind of platforms. A shift of paradigmis necessary at all levels of application development to yield portable and scalable implementations on the widest range of heterogeneous platforms. This paper presents a design flow for the hardware and software synthesis of heterogeneous systems allowing to automatically generate hardware and software components as well as appropriate interfaces, from a unique high-level description of the application, based on the dataflow paradigm, running onto heterogeneous architectures composed by reconfigurable hardware units and multicore processors. Experimental results based on the implementation of several video coding algorithms onto heterogeneous platforms are also provided to show the effectiveness of the approach both in terms of portability and scalability.","Title: A Simplified 8 × 8 Transformation and Quantization Real-Time IP-Block for MPEG-4 H.264/AVC Applications: a New Design Flow Approach\nYear: 2007\n\nAbstract: Current multimedia design processes suffer from the excessively large time spent on testing new IP-blocks with references based on large video encoders specifications ( usually several thousands lines of code). The appropriate testing of a single IP-block may require the conversion of the overall encoder from software to hardware, which is dificult to complete in the short time required by the competition-driven reduced time-to-market demanded for the adoption of a new video coding standard. This paper presents a new design flow to accelerate the conformance testing of an IP-block using the H. 264/AVC software reference model. An example block of the simplified 8 x 8 transformation and quantization, which is adopted in FRExt, is provided as a case study demonstrating the effectiveness of the approach.","Title: Reconfigurable video coding: a stream programming approach to the specification of new video coding standards\nYear: 2010\n\nAbstract: Current video coding standards, and their reference implementations, are architected as large monolithic and sequential algorithms, in spite of the considerable overlap of functionality between standards, and the fact that they are frequently implemented on highly parallel computing platforms. The former leads to unnecessary complexity in the standardization process, while the latter implies that implementations have to be rebuilt from the ground up to reflect the parallel nature of the target. The upcoming Reconfigurable Video Coding (RVC) standard currently developed at MPEG attempts to address these issues by building a framework that supports the construction of video standards as libraries of coding tools. These libraries can be incrementally updated and extended, and the tools in them can be aggregated to form complete codecs using a streaming (or dataflow) programming model, which preserves the inherent parallelism of the coding algorithm. This paper presents the RVC framework and its underlying data flow programming model, along with the tool support and initial results.","Title: Static and quasi-static compositions of stream processing applications from dynamic dataflow programs.\nYear: 2013\n\nAbstract: Dynamic dataflow models for their expressiveness properties have shown to represent more adequate and attractive solutions for describing state of the art signal processing applications. However, they are known to present potential run-time penalties when implementations are obtained by mapping and scheduling a dataflow network partition on a processing unit. In general terms, a completely static scheduling at compile-time of dynamic dataflow programs remains an unsolved problem. Several approaches for the composition of actors are promising approach that can significantly reduce the potential penalty of run-time scheduling thus increasing the overall performance of the system. This paper presents static and quasi-static composition techniques that results in a reduction of the portion of dynamic dataflow networks, by applying appropriate transformations to network partitions that after a specific analysis demonstrate to possess a predictable behaviour. Some experiments based on a video processing application ported on several system-on-chips show the achievable speedup corresponding to the reduction of the number of run-time scheduling decisions.","Title: Methodology for the hardware/software co-design of dataflow programs\nYear: 2011\n\nAbstract: New generations of multi-core processors and reconfigurable hardware platforms are expected to provide a dramatic increase of processing capabilities. However, one obstacle for exploiting all the promises of such new platforms is the legacy of current applications and the development methodologies used, which is deeply rooted in a sequential way of thinking. A paradigm shift is necessary at all levels of application development to yield portable and efficient implementations, capable of exploiting the full potential of such platforms. Dataflow programming is an alternative approach that address the problem of providing portable and scalable parallel applications. Dataflow programming is able to explicitly expose the intrinsic parallelism of applications. This paper presents a hardware/software co-design methodology that starting from a unique dataflow program enables, by the direct synthesis of both hardware (HDL) and software components (C/C++), to map a signal processing application onto heterogeneous systems architectures composed by reconfigurable hardware and multi-core processors. Experimental results based on the implementation of the MPEG-4 Simple Profile decoder onto an heterogeneous platform are also provided to show the capabilities and flexibility of the approach.","Title: Reconfigurable Media Coding: A New Specification Model for Multimedia Coders\nYear: 2007\n\nAbstract: Multimedia coding technology, after about 20 years of active research, has delivered a rich variety of different and complex coding algorithms. Selecting an appropriate subset of these algorithms would, in principle, enable a designer to produce the codec supporting any desired functionality as well as any desired trade-off between compression performance and im- plementation complexity. Currently, interoperability demands that this selection process be hard-wired into the normative descriptions of the codec, or at a lower level, into a predefined number of choices, known as profiles, codified within each standard specification. This paper presents an alternative paradigm for codec deployment that is currently under development by MPEG, known as Reconfigurable Media Coding (RMC). Using the RMC framework, arbitrary combinations of fundamental al- gorithms may be assembled, without predefined standardiza- tion, because everything necessary for specifying the decoding process is delivered alongside the content itself. This side- information consists of a description of the bitstream syntax, as well as a description of the decoder configuration. Decoder configuration information is provided as a description of the interconnections between algorithmic blocks. The approach has been validated by development of an RMC format that matches MPEG-4 Video, and then extending the format by adding new chroma-subsampling patterns.","Title: A platform for mixed HW/SW algorithm specifications for the exploration of SW and HW partitioning\nYear: 2007\n\nAbstract: The increasing complexity in particular of video and multimedia processing has lead to the need of developing the algorithms specification using software implementations that become in practice generic reference implementations. Mapping directly such software models in platforms made of processors and dedicated HW elements becomes harder and harder for the complexity of the models and for the large choice of possible partitioning options. This paper describes a new platform aiming at supporting the mapping of software specifications into mixed SW and HW implementations. The platform is supported by profiling capabilities specifically conceived to study data transfers between SW and HW modules. Such optimization capabilities can be used to achieve different objectives such as optimization of memory architectures or low power designs by the minimization of data transfers.","Title: Multimedia terminal architecture: An inter-operable approach\nYear: 2008\n\nAbstract: This paper addresses the inter-operability problem of multimedia terminal in media content delivery over heterogeneous networks and devices. We design and implement a terminal which includes a content browser providing presentation, navigation and interaction with MPEG-21 Digital Item Declaration (MPEG-21 DID) in order to support universal media access (UMA). We optimized the architecture in a client-server distributed approach with Web Service support. This terminal enables the MPEG-21 standard compliant content accessible on different terminal devices via common Web browsers. Such a design strategy illustrates a next-generation multimedia terminal supporting inter-operability in multimedia content adaptation over a heterogeneous delivery chain.","Title: Secure computing with the MPEG RVC framework\nYear: 2013\n\nAbstract: Recently, ISO/IEC standardized a dataflow-programming framework called Reconfigurable Video Coding (RVC) for the specification of video codecs. The RVC framework aims at providing the specification of a system at a high abstraction level so that the functionality (or behavior) of the system become independent of implementation details. The idea is to specify a system so that only intrinsic features of the algorithms are explicitly expressed, whereas implementation choices can then be made only once specific target platforms have been chosen. With this system design approach, one abstract design can be used to automatically create implementations towards multiple target platforms. In this paper, we report our investigations on applying the methodology standardized by the MPEG RVC framework to develop secure computing in the domains of cryptography and multimedia security, leading to the conclusion that the RVC framework can successfully be applied as a general-purpose framework to other fields beyond multimedia coding. This paper also highlights the challenges we faced in conducting our study, and how our study helped the RVC and the secure computing communities benefited from each other. Our investigations started with the development of a Crypto Tools Library (CTL) based on RVC, which covers a number of widely used ciphers and cryptographic hash functions such as AES, Triple DES, ARC4 and SHA-2. Performance benchmarking results on the RVC-based AES and SHA-2 implementations in both C and Java revealed that the automatically generated implementations can achieve a comparable performance to some manually written reference implementations. We also demonstrated that the RVC framework can easily produce implementations with multi-core support without any change to the RVC code. A security protocol for mutual authentication was also implemented to demonstrate how one can build heterogeneous systems easily with RVC. By combining CTL with Video Tool Library (a standard library defined by the RVC standard), a non-standard RVC-based H.264/AVC encoder and a non-standard RVC-based JPEG codec, we further demonstrated the benefits of using RVC to develop different kinds of multimedia security applications, which include joint multimedia encryption-compression schemes, digital watermarking and image steganography in JPEG compressed domain. Our study has shown that RVC can be used as a general-purpose implementation-independent development framework for diverse data-driven applications with different complexities.","Title: High level extraction of SoC architectural information from generic C algorithmic descriptions\nYear: 2005\n\nAbstract: The complexity of nowadays, algorithms in terms of number of lines of codes and cross-relations among processing algorithms that are activated by specific input signals, goes far beyond what the designer can reasonably grasp from the \"pencil and paper\" analysis of the (software) specifications. Moreover, depending on the implementation goal different measures and metrics are required at different steps of the implementation methodology or design flow of SoC. The process of extracting the desired measures needs to be supported by appropriate automatic tools, since code rewriting, at each design stage, may result resource consuming and error prone. This paper presents an integrated tool for automatic analysis capable of producing complexity results based on rich and customizable metrics. The tool is based on a C virtual machine that allows extracting from any C program execution the operations and data-flow information, according to the defined metrics. The tool capabilities include the simulation of virtual memory architectures.","Title: Automatic Synthesis of Parsers and Validation of Bitstreams Within the MPEG Reconfigurable Video Coding Framework\nYear: 2011\n\nAbstract: Video coding technology has evolved in the past years into a variety of different and complex algorithms. So far the specifications of such standard algorithms have been done case by case, providing monolithic textual and reference software specifications, but without paying any attention to the possibility of further improvements of such monolithic standards. The MPEG Reconfigurable Video Coding (RVC) framework is a new ISO/IEC standard, currently under its final stage of development aiming at providing video codec specifications at the level of coding tools instead of monolithic descriptions. The possibility to select a subset of standard video coding algorithms to specify a decoder that satisfies application specific constraints is very attractive. However, such possibility to reconfigure codecs requires systematic procedures and tools capable of describing the new bitstream syntaxes of such new codecs. Moreover, it becomes also necessary to generate the associated parsers, capable of parsing the new bitstreams. This paper further explains the problem and describes the technologies used to describe new bitstream syntaxes. Additionally, the paper describes the methodologies and the tools for the validation of bitstream syntaxes descriptions as well as a systematic procedure for automatically synthesizing parsers from the bitstream descriptions.","Title: High-level algorithmic complexity evaluation for system design\nYear: 2003\n\nAbstract: The increasing complexity of processing algorithms has led to the need of more and more intensive specification and validation by means of software implementations. As the complexity grows, the intuitive understanding of the specific processing needs becomes harder and harder. Hence, the architectural implementation choices or the choices between different possible software/hardware partitioning become extremely difficult tasks. Moreover, it is also desirable to understand and measure the algorithm complexity at the highest possible level near to the algorithmic level so as to be able to take the more appropriate actions. Automatic tools to perform such analysis become nowadays a fundamental need.In this paper, the requirements of a suitable algorithmic complexity evaluation technology are discussed, with a particular emphasis to the problem of the analysis of multimedia systems and signal processing algorithms. A brief review about limitations and weaknesses of existing tools is given, specifying the characteristics of ideal \"complexity evaluation systems\". A new approach is described, called here Software Instrumentation Tool, SIT, yielding an automatic software tool able to extract information not depending on the simulation platform, keeping into account specific input data and resulting in a good and useful measure of the desired high-level algorithmic complexity.","Title: Methods to explore design space for MPEG RMC codec specifications\nYear: 2013\n\nAbstract: The recent MPEG Reconfigurable Media Coding (RMC) standard aims at defining media processing specifications (e.g. video codecs) in a form that abstracts from the implementation platform, but at the same time is an appropriate starting point for implementation on specific targets. To this end, the RMC framework has standardized both an asynchronous dataflow model of computation and an associated specification language. Either are providing the formalism and the theoretical foundation for multimedia specifications. Even though these specifications are abstract and platform-independent the new approach of developing implementations from such initial specifications presents obvious advantages over the approaches based on classical sequential specifications. The advantages appear particularly appealing when targeting the current and emerging homogeneous and heterogeneous manycore or multicore processing platforms. These highly parallel computing machines are gradually replacing single-core processors, particularly when the system design aims at reducing power dissipation or at increasing throughput. However, a straightforward mapping of an abstract dataflow specification onto a concurrent and heterogeneous platform does often not produce an efficient result. Before an abstract specification can be translated into an efficient implementation in software and hardware, the dataflow networks need to be partitioned and then mapped to individual processing elements. Moreover, system performance requirements need to be accounted for in the design optimization process. This paper discusses the state of the art of the combinatorial problems that need to be faced at this design space exploration step. Some recent developments and experimental results for image and video coding applications are illustrated. Both well-known and novel heuristics for problems such as mapping, scheduling and buffer minimization are investigated in the specific context of exploring the design space of dataflow program implementations.","Title: A Multimedia Terminal Supporting Adaptation for QoS Control\nYear: 2008\n\nAbstract: This paper addresses the End-to-End Quality of Service (QoS) guarantees and control for multimedia content delivery over heterogeneous networks, with a particular focus on end user terminal perspective. A multimedia terminal which embeds different probes to monitor network conditions and end user perceptual characteristics has been conceived and implemented. A series of QoS mapping between perception and adaptation spaces are yielded by means of the parameters provided by the QoS probes, facilitating content adaptation enabled by any generic adaptation server or intermediate service. Such a design approach illustrates a possible architecture for next-generation multimedia end user system supporting QoS control and content adaptation over a heterogeneous delivery chain.","Title: Overlapped motion compensation for subband coding of video sequences\nYear: 1996\n\nAbstract: Block motion compensation (MC) is widely used in hybrid coding schemes. The presence of motion discontinuities inside the blocks introduces inefficiencies that reduce the performances of MC methods. Moreover the displaced frame difference (DFD) image shows block discontinuities. This fact is the main difficulty in using block-based MC in subband coding systems. This limitation does not appear in transform-based algorithms, where the boundaries of the transform support coincide with the MC block boundaries. Overlapped window motion estimation and compensation have been proposed to overcome these limitations leading to a reduction of the DFD energy and of the blocking artifacts. Overlapped MC is eqivalent to a linear combination of predictors based on neighboring block motion vectors. In this paper we describe a motion compensation scheme with new overlapped window modes. We report the improvements achieved in terms of DFD energy reduction and block boundaries reduction. Then a complete coding system based on subband decomposition is defined to evaluate the performances of the extended MC scheme in terms of bit rate reduction, SNR, and perceived visual quality. Simulation results have shown noticeable gains of the overlapped motion compensation over the MPEG2 MC scheme used for subband coding increasing only the complexity of the MC part.","Title: A Co-Design Platform For Algorithm/Architecture Design Exploration\nYear: 2008\n\nAbstract: The efficient implementation of multimedia algorithms, for the ever increasing complexity of the specifications and the emergence of the new generation of processing platforms characterized by multicore and multicomponent parallel architectures, requires appropriate design space exploration procedures as preliminary step for any implementation. This paper describes a new platform aiming at supporting the algorithm and architecture co-exploration starting by a pure software specification that is gradually transformed into a possibly mixed SW and HW implementation. The process is based on profiling capabilities supported by the new platform specifically conceived to study and optimize data flows and data transfers between SW and HW modules. Different explicit or implicit (i.e. virtual memory extensions) data transfer modes can be profiled in the co-exploration process, by using minimal SW reconfiguration, thus minimizing any SW/HW re-writing effort in the co-exploration stage. Such optimization capabilities can be used to achieve different optimization objectives such as the optimization of memory architectures or low power designs by appropriate minimization of data transfers. Experimental results and an example of the usage of the platform are provided for the design case of a motion estimation module for video encoding.","Title: Pipeline synthesis and optimization of FPGA-based video processing applications with CAL.\nYear: 2011\n\nAbstract: This article describes a pipeline synthesis and optimization technique that increases data throughput of FPGA-based system using minimum pipeline resources. The technique is applied on CAL dataflow language, and designed based on relations, matrices, and graphs. First, the initial as-soon-as-possible (ASAP) and as-late-as-possible (ALAP) schedules, and the corresponding mobility of operators are generated. From this, operator coloring technique is used on conflict and nonconflict directed graphs using recursive functions and explicit stack mechanisms. For each feasible number of pipeline stages, a pipeline schedule with minimum total register width is taken as an optimal coloring, which is then automatically transformed to a description in CAL. The generated pipelined CAL descriptions are finally synthesized to hardware description languages for FPGA implementation. Experimental results of three video processing applications demonstrate up to 3.9× higher throughput for pipelined compared to non-pipelined implementations, and average total pipeline register width reduction of up to 39.6 and 49.9% between the optimal, and ASAP and ALAP pipeline schedules, respectively.","Title: Smart camera based on embedded HW/SW coprocessor\nYear: 2008\n\nAbstract: This paper describes an image acquisition and a processing system based on a new coprocessor architecture designed for CMOS sensor imaging. The system exploits the full potential CMOS selective access imaging technology because the coprocessor unit is integrated into the image acquisition loop. The acquisition and coprocessing architecture are compatible with the majority of CMOS sensors. It enables the dynamic selection of a wide variety of acquisition modes as well as the reconfiguration and implementation of high-performance image preprocessing algorithms (calibration, filtering, denoising, binarization, pattern recognition). Furthermore, the processing and data transfer, from the CMOS sensor to the processor, can be operated simultaneously to increase achievable performances. The coprocessor architecture has been designed so as to obtain a unit that can be configured on the fly, in terms of type and number of chained processing stages (up to 8 successive predefined preprocessing stages), during the image acquisition process that can be defined by the user according to each specific application requirement. Examples of acquisition and processing performances are reported and compared to classical image acquisition systems based on standard modular PC platforms. The experimental results show a considerable increase of the achievable performances.","Title: An efficient motion estimation algorithm based on tracing techniques on large search windows\nYear: 1998\n\nAbstract: Motion estimation represents the most computationally intensive task for all efficient motion compensated compression standards. This fact, despite the several efforts aiming at reducing its complexity, still constitutes a serious obstacle for obtaining the highest quality results theoretically achievable by the standard. This is particularly evident when critical conditions occur, such as when very large search windows are needed to have efficient motion prediction for sequences containing large displacements. In this paper we present a new block motion estimation technique, based on the combination of the tracing of trajectories obtained from the already coded motion field and a genetic heuristic search. This technique can be applied to any group of picture structure of any block based compression standard, with a complexity reduction factor up to more than two orders of magnitude at optimal coding results","Title: A Platform for the Development and the Validation of HW IP Components Starting from Reference Software Specifications\nYear: 2008\n\nAbstract: Signal processing algorithms become more and more performing and efficient as result of new developments or at the release of new standards. This fact is particularly true in the field of multimedia and video compression. However, at each improvement in efficiency and functionality the complexity of the algorithms is also increasing. Textual specifications, that in the past were the original form of specifications, have been sub- stituted by reference software packages which have become the starting point of any design flow leading to the implementation of the algorithm. Therefore designing an embedded application has become equivalent to port a generic SW on a, possibly heterogeneous, embedded platform. Such operation is getting more and more difficult and resource consuming for the increased algorithm complexity and for the wide range of architectural solutions provided by a plethora of heterogeneous SW/HW embedded platforms. This paper describes a new platform aiming at supporting a step-by-step mapping of a reference software (i.e. generic and non optimized sequential software specification) into a SW and HW implementation. The platform provides a seamless interface between the software and hardware environments and in addition is supported by profiling capabilities able to analyze the transfers of data between HW and SW parts of the algorithm. Such profiling capabilities can help the designer to achieve different implementations aiming at specific objectives such as the optimization of hardware processing resources, of the memory architectures, or the minimization of data transfers to reach low power designs.","Title: Reconfigurable media coding: An overview\nYear: 2013\n\nAbstract: This paper provides an overview of the rationale of the Reconfigurable Media Coding framework developed by MPEG standardization committee to overcome the limits of traditional ways of providing decoder specifications. Such framework is an extension of the Reconfigurable Video coding framework now encompassing also 3D Graphics coding standard. The idea of this approach is to specify decoders using an actor dataflow based representation consisting of self-contained processing units (coding tools) connected altogether and communicating by explicitly exchanging data. Such representation provides a specification for which several properties of the algorithms interesting for codec implementations are explicitly exposed and can be used for exploring different implementation objectives.","Title: Reconfigurable video coding on multicore\nYear: 2009\n\nAbstract: This article provides an overview of the main objectives of the new RVC standard, with an emphasis on the features that enable efficient implementation on platforms with multiple cores. A brief introduction to the methodologies that efficiently map RVC codec specifications to multicore platforms is accompanied with an example of the possible breakthroughs that are expected to occur in the design a...","Title: Building multimedia security applications in the MPEG reconfigurable video coding (RVC) framework\nYear: 2011\n\nAbstract: Although used by most of system developers, imperative languages are known for not being able to provide easily reconfigurable, platform independent and strictly modular applications. ISO/IEC has recently developed a new video coding standard called Reconfigurable Video Coding (RVC), with the objective of providing modular and concurrent specifications of complex video codecs that constitute a better starting point for implementation of applications using video compression. Multimedia security applications are traditionally developed in imperative languages mainly because the required multimedia codecs were only available in specification and implementations based on imperative languages. Therefore, aside from the technical challenges inherited from multimedia codecs, multimedia security applications also face a number of other challenges which are only specific to them. Since a number of multimedia codecs are already available in the RVC framework, multimedia security applications can now also be developed using this new development framework. This paper explains why the RVC framework approach can be used to efficiently overcome those technical challenges better than existing imperative languages. In addition, the paper demonstrates how the RVC framework can be used to quickly develop multimedia security applications by presenting some examples including a joint H.264/AVC video encryption-encoding system, a joint JPEG image encryption-encoding system and a image watermarking system in JPEG compressed-domain.","Title: Special Issue: Algorithm/Architecture Co-Exploration of Visual Computing on Emerging Platforms\nYear: 2009\n\nAbstract: Provides notice of upcoming special issue(s) of interest to practitioners and researchers.","Title: Reconfigurable Media Coding: Self-Describing Multimedia Bitstreams\nYear: 2007\n\nAbstract: The development of MP3 and JPEG sparked an explosion in digital content on the internet. These early encoding formats have since been joined by many others, including Quicktime, Ogg, MPEG-2 and MPEG-4, which poses an escalating challenge to vendors wishing to develop devices that interoperate with as much content as possible. This paper presents aspects of Reconfigurable Media Coding (RMC), a project currently underway at MPEG to define a self-describing bitstream format. In other words, an RMC bitstream contains metadata to assemble a decoder from a fundamental building-blocks, as well as a schema that describes the syntax of the content data, and how it may be parsed. RMC makes it easy to extend (reconfigure) existing codecs, for example adding error resilience or new chroma-subsampling profiles, or to build entirely new codecs. This paper addresses the bitstream syntax component of RMC, validating the approach by applying it to the recent MPEG-4 Video simple profile coder.","Title: A hybrid decoder configuration of MPEG-4 and AVS in reconfigurable video coding framework\nYear: 2009\n\nAbstract: This demonstration shows that the RVC framework offers a great flexibility in selecting coding tools for decoder reconfigurations to satisfy a wide variety of different applications by showing a hybrid decoder reconfiguration using coding tools from MPEG and AVS Video Tool Library (VTL). Compared with the original MPEG-4 simple profile (SP), complexity of the reconfigured decoder is reduced whereas the performance is improved gradually as the bitrate increases.","Title: Video decoder reconfigurations and AVS extensions in the new MPEG reconfigurable video coding framework\nYear: 2008\n\nAbstract: Multimedia devices are now required to support multiple coding standards. Supporting seamlessly both interoperability between standards and flexibility for application specific optimizations is a great challenge for current video coding technology. After a brief description of the new MPEG reconfigurable video coding (RVC) framework, this paper describes possible decoder reconfigurations within this framework. The essential idea behind this framework is to reuse as most as possible the algorithms or architectures which are common to several different standards and to reconfigure video decoders in a flexible way at the coding tool level. A coding tool is an encapsulated piece of algorithm. Reconfiguration can address specific optimization objectives such as improvement in colour reproduction or higher performance at high bitrate. These simple examples show that the tool level definition of the video tool library is flexible enough to support the incremental introduction of new coding algorithms, the usage of algorithms taken from different video standards (i.e. AVS is provided in one example), and the possibility of high level reconfigurations. Thus, this paper demonstrates that the RVC framework offers a great flexibility in selecting coding tools for decoder reconfigurations to satisfy a wide variety of different applications.","Title: An Integrated Environment For Hw/Sw Co-Design Based On A Cal Specification And Hw/Sw Code Generators\nYear: 2009\n\nAbstract: This demonstration presents an integrated environment that translates a CAL-based dataflow specification [1] into a heterogeneous implementation, composed by HDL and C codes. The demonstration focuses on the capability of the co-design environment to automatically build an executable heterogeneous system implementation running on a platform composed of a processor and a FPGA from the annotation of the CAL specification. The possibility of direct synthesis from a high level specification is a crucial issue for enabling efficient re-design cycles that include rapid prototyping and validation of performances of the final implementation. The design approach enabled by such integrated environment is particularly suited for development of complex processing systems such as video codecs. As a case study, the demonstration provides the analysis and validation of different software and hardware partitioning of a MPEG-4 Simple Profile decoder.","Title: Real-Time Constraints and Prediction of Video Decoding Time for Multimedia Systems\nYear: 1998\n\nAbstract: The implementation of software based video/audio decoders is an advantageous solution over traditional dedicated hardware systems. However, simultaneously guaranteeing real-time performance, needed for processing video/audio bit-streams, and an efficient use of the processing power, remains a very difficult task. In this paper, we briefly discuss the main reasons of such difficulties and we present a new technique able to predict the decoding time of compressed video bit-streams without the need of the actual decoding. This result can be obtained when appropriate statistics about the actual decoding process are included and transmitted with the compressed video data. We also show how such results can be used to implement new efficient processing resource allocation strategies. New possible schemes of intelligent interactions, and in particular an efficient implementation of Computational Graceful Degradation, between the encoder and the real-time OS are also proposed. An example of results obtained implementing the proposed technique for the MPEG-4 VM6 video algorithm is presented. Although the techniques and concepts presented in this paper are of general application, they can only be used for video compression standards capable of transmitting in any appropriate form the associated statistical coding information. This capability has been included in the new defined MPEG-4 standard.","Title: Performance Benchmarking Of Rvc Based Multimedia Specifications\nYear: 2013\n\nAbstract: The Reconfigurable Video Coding (RVC) framework was developed to specify video codecs as abstract and as much as possible implementation-agnostic descriptions, which are supposed to be processed by code synthesis tools to automatically generate implementations for different target languages and platforms. However, there are still questions about if the run-time performance of these automatically generated RVC-based codec implementations is good enough to run efficiently on different target platforms. In this paper, we present a performance benchmarking study on various RVC-based multimedia specifications (H.264/AVC and JPEG codecs, and four multimedia security systems based on these codecs), which covers the following two aspects: 1) the run-time performance against their corresponding non-RVC implementations on a single-core machine; 2) the performance gain these RVC-based implementations on a dual-core machine. Based on our benchmarking results, which show that RVC-based multimedia implementations achieve adequate/acceptable performance, we conclude that RVC has the potential to become a general-purpose but still performance-efficient development framework for many application domains.","Title: The MIN PFS problem and piecewise linear model estimation\nYear: 2002\n\nAbstract: We consider a new combinatorial optimization problem related to linear systems (MIN PFS) that consists, given an infeasible system, in finding a partition into a minimum number of feasible subsystems. MIN PFS allows formalization of the fundamental problem of piecewise linear model estimation, which is an attractive alternative when modeling a wide range of nonlinear phenomena. Since MIN PFS turns out to be NP-hard to approximate within every factor strictly smaller than 3/2 and we are mainly interested in real-time applications, we propose a greedy strategy based on randomized and thermal variants of the classical Agmon-Motzkin-Schoenberg relaxation method for solving systems of linear inequalities. Our method provides good approximate solutions in a short amount of time. The potential of our approach and the performance of our algorithm are demonstrated on two challenging problems from image and signal processing. The first one is that of detecting line segments in digital images and the second one that of modeling time-series using piecewise linear autoregressive models. In both cases the MIN PFS-based approach presents various advantages with respect to conventional alternatives, including wider range of applicability, lower computational requirements and no need for a priori assumptions regarding the underlying structure of the data.","Title: A computationally efficient method for polyphonic pitch estimation\nYear: 2009\n\nAbstract: This paper presents a computationally efficient method for polyphonic pitch estimation. The method employs the Fast Resonator Time-Frequency Image (RTFI) as the basic time-frequency analysis tool. The approach is composed of two main stages. First, a preliminary pitch estimation is obtained by means of a simple peak-picking procedure in the pitch energy spectrum. Such spectrum is calculated from the original RTFI energy spectrum according to harmonic grouping principles. Then the incorrect estimations are removed according to spectral irregularity and knowledge of the harmonic structures of the music notes played on commonly used music instruments. The new approach is compared with a variety of other frame-based polyphonic pitch estimation methods, and results demonstrate the high performance and computational efficiency of the approach.","Title: CAL Dataflow Components for an MPEG RVC AVC Baseline Encoder\nYear: 2011\n\nAbstract: In this paper, an efficient H.264/AVC baseline encoder, described in RVC-CAL actor language, is introduced. The main aim of the paper is twofold: a) to demonstrate the flexibility and ease that is provided by RVC-CAL, which allows for efficient implementation of the presented encoder, and b) to shed light on the advantages that can be brought into the RVC framework by including such encoding tools. The main modules of the designed encoder include: Inter Frame Prediction (Motion Estimation/Compensation), Intra Frame Prediction, and Entropy Coding. Descriptions of the designed modules, accompanied with RVC-CAL design issues are provided. A comparison between different development approaches is also provided. The obtained results show that specifying complex video codecs (e.g. H.264/AVC encoder) using RVC-CAL followed by automatic translation into HDL, which is achievable by the tools that support the standard, results in more efficient HW implementation compared to the traditional HW design flow. A discussion that explains the reasons behind such results concludes the paper.","Title: Techniques for Optimization of Net Algorithms\nYear: 2002\n\nAbstract: In this paper, techniques for optimization of net algorithms describing parallel asynchronous computations and derived from cycling and branching behavioral descriptions are presented. The parallelization level of the algorithms is defined by a set of parallel operator pairs. The optimization techniques cover the two key steps of parallelization flow: the generation of an optimal initial set of parallel operator pairs to meet the constraints on the execution time or implementation cost, and the generation of the final set of pairs to solve the net algorithm existence problem. The quality of the proposed techniques is evaluated by experimental results. The techniques based on the minimization of the net algorithm critical paths estimated using the maximal weight cliques of the sequential and parallel operator graphs constitute the most efficient approach to the generation of the initial and final sets of parallel operator pairs.","Title: High-level dataflow design of signal processing systems for reconfigurable and multicore heterogeneous platforms\nYear: 2014\n\nAbstract: The potential computational power of today multicore processors has drastically improved compared to the single processor architecture. Since the trend of increasing the processor frequency is almost over, the competition for increased performance has moved on the number of cores. Consequently, the fundamental feature of system designs and their associated design flows and tools need to change, so that, to support the scalable parallelism and the design portability. The same feature can be exploited to design reconfigurable hardware, such as FPGAs, which leads to rethink the mapping of sequential algorithms to HDL. The sequential programming paradigm, widely used for programming single processor systems, does not naturally provide explicit or implicit forms of scalable parallelism. Conversely, dataflow programming is an approach that naturally provides parallelism and the potential to unify SW and HDL designs on heterogeneous platforms. This study describes a dataflow-based design methodology aiming at a unified co-design and co-synthesis of heterogeneous systems. Experimental results on the implementation of a JPEG codec and a MPEG 4 SP decoder on heterogeneous platforms demonstrate the flexibility and capabilities of this design approach.","Title: Representing Guard Dependencies in Dataflow Execution Traces\nYear: 2013\n\nAbstract: Heterogeneous parallel systems are becoming mainstream computing platforms nowadays. One of the main challenges the development community is currently facing is how to fully exploit the available computational power when porting existing programs or developing new ones with available techniques. In this direction, several design space exploration methods have been presented and extensively adopted. However, defining the feasible design space of a dynamic dataflow program still remains an open issue. This paper proposes a novel methodology for defining such a space through a serial execution. Homotopy theoretic methods are used to demonstrate how the design space of a program can be reconstructed from its serial execution trajectory. Moreover, the concept of dependencies graph of a dataflow program defined in the literature is extended with the definition of two new kinds of dependencies - the Guard Enable and Disable - and the 3-tuple notion needed to represent them.","Title: Overview of the MPEG Reconfigurable Video Coding Framework\nYear: 2011\n\nAbstract: Video coding technology in the last 20 years has evolved producing a variety of different and complex algorithms and coding standards. So far the specification of such standards, and of the algorithms that build them, has been done case by case providing monolithic textual and reference software specifications in different forms and programming languages. However, very little attention has been given to provide a specification formalism that explicitly presents common components between standards, and the incremental modifications of such monolithic standards. The MPEG Reconfigurable Video Coding (RVC) framework is a new ISO standard currently under its final stage of standardization, aiming at providing video codec specifications at the level of library components instead of monolithic algorithms. The new concept is to be able to specify a decoder of an existing standard or a completely new configuration that may better satisfy application-specific constraints by selecting standard components from a library of standard coding algorithms. The possibility of dynamic configuration and reconfiguration of codecs also requires new methodologies and new tools for describing the new bitstream syntaxes and the parsers of such new codecs. The RVC framework is based on the usage of a new actor/ dataflow oriented language called CAL for the specification of the standard library and instantiation of the RVC decoder model. This language has been specifically designed for modeling complex signal processing systems. CAL dataflow models expose the intrinsic concurrency of the algorithms by employing the notions of actor programming and dataflow. The paper gives an overview of the concepts and technologies building the standard RVC framework and the non standard tools supporting the RVC model from the instantiation and simulation of the CAL model to software and/or hardware code synthesis.","Title: OpenDF: a dataflow toolset for reconfigurable hardware and multicore systems\nYear: 2008\n\nAbstract: This paper presents the OpenDF framework and recalls that dataflow programming was once invented to address the problem of parallel computing. We discuss the problems with an imperative style, von Neumann programs, and present what we believe are the advantages of using a dataflow programming model. The CAL actor language is briefly presented and its role in the ISO/MPEG standard is discussed. The Dataflow Interchange Format (DIF) and related tools can be used for analysis of actors and networks, demonstrating the advantages of a dataflow approach. Finally, an overview of a case study implementing an MPEG- 4 decoder is given.","Title: Fast Line Detection Algorithms Based on Combinatorial Optimization\nYear: 2001\n\nAbstract: In this paper we present a new class of algorithms for detecting lines in digital images. The approach is based on a general formulation of a combinatorial optimization problem. It aims at estimating piecewise linear models. A linear system is constructed with the coordinates of all contour points in the image as coefficients and the line parameters as unknowns. The resulting linear system is then partitioned into a close-to-minimum number of consistent subsystems using a greedy strategy based on a thermal variant of the perceptron algorithm. While the partition into consistent subsystems yields the classification of the corresponding image points into a close-to-minimum number of lines. A comparison with the standard Hough Transform and the Randomized Hough Transform shows the considerable advantages of our combinatorial optimization approach in terms of memory requirements, time complexity, robustness with respect to noise, possibility of introducing \"a priori\" knowledge, and quality of the solutions regardless of the algorithm parameter settings.","Title: Quasi-Static Scheduling of CAL Actor Networks for Reconfigurable Video Coding\nYear: 2011\n\nAbstract: The upcoming Reconfigurable Video Coding (RVC) standard from MPEG (ISO / IEC SC29WG11) defines a library of coding tools to specify existing or new compressed video formats and decoders. The coding tool library has been written in a dataflow/actor-oriented language named CAL. Each coding tool (actor) can be represented with an extended finite state machine and the data communication between the tools are described as dataflow graphs. This paper proposes an approach to model the CAL actor network with Parameterized Synchronous Data Flow and to derive a quasi-static multiprocessor execution schedule for the system. In addition to proposing a scheduling approach for RVC, an extension to the well-known permutation flow shop scheduling problem that enables rapid run-time scheduling of RVC tasks, is introduced.","Title: A Software/Hardware Platform for Rapid Prototyping of Video and Multimedia Designs\nYear: 2005\n\nAbstract: Traditional design and test of complex multimedia systems involves a large number of test vectors and is a difficult and time-consuming task. The simulation times are prohibitively long on current desktop computers. Driving actual design scenarios and timing burst behavior which produce real-time effects is difficult to do with current simulation environments. This paper describes a rapid emulation framework for accessing multiple hardware IP blocks on an FPGA. This solution involves an abstraction of the FPGA platform by having a virtual socket layer that resides between the design and the test vehicles. A rapid prototyping platform is thus created, and its use with complex video and multimedia systems is described.","Title: The Reconfigurable Video Coding Standard [Standards in a Nutshell]\nYear: 2010\n\nAbstract: More than two decades of research in digital video technologies, together with the emergence of successful international standards for digital video compression, have led to a wide variety of digital video products using video compression for professional and consumer applications. Although many of these video compression standards share common and/or similar coding tools, there is currently no explicit way to exploit such commonalities at the level of the specifications nor at the level of implementations. Moreover, the possibility of taking advantage of the benefits of the continuous improvements of coding technology is only possible by replacing an old standard with a new one. This usually results in the replacement of the existing multimedia devices with new ones capable of handling the new deployed standards. Such necessity is not always well accept-ed by the public and professionals for obvious reasons.","Title: A new time-frequency representation for music signal analysis: Resonator time-frequency image\nYear: 2007\n\nAbstract: Most of music related tasks need a joint time-frequency analysis because a music signal varies with time. The existing time-frequency analysis approaches show some serious limitations for application in music signal processing. This paper presents an original frequency-dependent time-frequency analysis tool called the Resonator Time-Frequency Image (RTFI). The RTFI is implemented by a first-order complex resonator bank so as to be computation-efficient. Different music analysis tasks may have different time-frequency resolution requirements. Using the RTFI, one can select different time-frequency resolutions, such as uniform analysis, constant-Q analysis, or ear-like analysis by simply setting different parameters; and letting the RTFI generalize all these analyses in one framework. An example of using the RTFI in music onset detection is introduced.","Title: A Perceptron-Based Approach to Piecewise Linear Modeling with an Application to Time Series\nYear: 1997\n\nAbstract: . Piecewise linear models are attractive when modeling a widerange of nonlinear phenomena but determining simultaneously the datapartition and the parameter values of the corresponding submodels is achallenging problem. We show that this problem can be formulated asthat of partitioning an inconsistent linear system into a minimum numberof consistent subsystems and we describe a greedy algorithm, basedon a simple variant of the perceptron procedure, which provides goodapproximate...","Title: SMIL to MPEG-4 BIFS Conversion\nYear: 2006\n\nAbstract: The current trend in the evolution of the Web is towards an every increasing demand for personalized Web contents. Tailoring Web resources to the characteristics of heterogeneous client devices and user preferences opens two main novel issues in the ...","Title: Actor Merging for Dataflow Process Networks\nYear: 2015\n\nAbstract: Dataflow process networks provide a versatile model of computation for specifying signal processing applications in a platform independent fashion. This attractive feature of dataflow has lately been realized in dataflow programming tools that allow synthesizing the same application specification as both fixed hardware circuits and as software for programmable processors. However, in practice, the specification granularity of the dataflow program remains an arbitrary choice of the designer. Dataflow specifications of the same application with equivalent I/O behaviour can range from a single dataflow actor to a very fine grained network composed of elementary processing operations. A very fine grained dataflow specification might result into a high performance implementation when synthesized as hardware, but might perform poorly when executed on a programmable processor. This article presents actor merging as one solution for this performance portability problem of dataflow programs. In contrast to previous work around actor merging, this article presents a methodology that can merge also dynamic dataflow actors. To support these claims, results of experiments on several processing platforms and application examples ranging from telecommunications to video compression are reported.","Title: Image visual quality restoration by cancellation of the unmasked noise\nYear: 1994\n\nAbstract: The aim of image restoration is to find an estimate of the ideal image using a priori information about blur and/or noise and/or the ideal image. Classical criterion are minimum least square, minimum mean square error or maximum a posteriori probability. The choice of the criterion used to measure the estimation quality is crucial for the design of the restoration algorithm. The authors propose a new criterion based on a visual model: it is based on perceptual masking. Thereafter, they propose a new restoration algorithm dealing only with additive noise. The perceptual components of the image to restore which are corrupted by an additive noise above a visibility threshold are simply set to zero. Some results obtained for the post-processing of JPEG images are presented","Title: Exploring MPEG HEVC decoder parallelism for the efficient porting onto many-core platforms.\nYear: 2014\n\nAbstract: MPEG High Efficient Video Coding (HEVC) is likely to emerge as the video coding standard for HD and Ultra-HD TV resolutions. The two elements that push HEVC beyond the previous standards are a higher compression efficiency of about a factor of two, and the introduction of new coding tools, tiles and wavefront that are intended to ease the largely increased encoding complexity particularly for Ultra HD resolutions such as 4K and 8K. However, for HEVC decoder implementations, the achievement of the desired performance on massive parallel platforms cannot rely on the use of such optional (not enforced by MPEG profiles) tools. This paper reports results about the intrinsic parallelism of compliant HEVC decoding algorithms obtained by analyzing a dataflow implementation written using the standard language specified in ISO/IEC 23001-4 and structured attempting to maximize the algorithmic potential parallelism. The experimental results show what is the parallelism achieved by different dataflow architectures and how it can be further combined with the parallelism achieved by relying on tiles and wavefront, whenever they would be available, for porting a compliant HEVC decoder on massive parallel many-core platforms.","Title: Characterizing communication behavior of dataflow programs using trace analysis\nYear: 2014\n\nAbstract: This paper investigates the relationship between two ways of analyzing streaming systems: trace analysis for dataflow programs with firing, and network calculus for network flows. While the former focuses on the structure of the dataflow computation while idealizing the interaction with the environment, the latter characterizes the temporal properties of flows of data, largely abstracting from the computations that connect them. In this work, we show how a trace analysis can be used to derive a description of communication behavior of a dataflow program in terms of network calculus, which is then applied to answering a question about the buffer sizing. The example being studied is an MPEG-4 video decoder.","Title: A methodology for optimizing buffer sizes of dynamic dataflow fpgas implementations\nYear: 2014\n\nAbstract: Minimizing buffer sizes of dynamic dataflow implementations without introducing deadlocks or reducing the design performance is in general an important and useful design objective. Indeed, buffer sizes that are too small causing a system to deadlock during execution, or dimensioning unnecessarily large sizes leading to a resource inefficient design are both not a desired design option. This paper presents an implementation, validation, and comparison of several buffer size optimization techniques for the generic class of dynamic dataflow model of computation called the dataflow process network. The paper presents an heuristic capable of finding a close-to-minimum buffer size configuration for deadlock-free executions, and a methodology to efficiently explore different configurations for feasible design alternatives. The approach is demonstrated using as experimental design case, an MPEG-4 AVC/H.264 decoder implemented on an FPGA.","Title: Profiling of Dataflow Programs Using Post Mortem Causation Traces\nYear: 2012\n\nAbstract: The natural representation of data streams, parallelism, and composition has made dataflow an attractive programming model for expressing a wide range of stream and media processing applications, and has led MPEG and ISO to base their latest video coding standards on this model. This paper describes and compares methodologies and metrics for the optimization of signal processing algorithms represented as dataflow programs. Our approach is based on the analysis of traces and addresses some of the complexity challenges that arise from the very large data sets that are required for evaluating real-world applications. The methodology and experimental results are demonstrated and evaluated in two at-size case studies, an MPEG-4 SP and an AVC/H.264 video decoders.","Title: A Virtual Socket Framework for Rapid Emulation of Video and Multimedia Designs\nYear: 2005\n\nAbstract: Traditional design and test of complex multimedia systems involves a large number of test vectors and is a difficult and time-consuming task. The simulation times are prohibitively long on current desktop computers. Driving actual design scenarios and timing burst behavior which produce real-time effects is difficult to do with current simulation environments. This paper describes a rapid emulation framework for accessing multiple hardware IP blocks on an FPGA. This solution involves an abstraction of the FPGA platform by having a virtual socket layer that resides between the design and the test vehicles. A rapid prototyping platform is thus created, and its use with complex video and multimedia systems is described.","Title: Configurable motion-estimation hardware accelerator module for the MPEG-4 reference hardware description platform\nYear: 2005\n\nAbstract: This paper describes a motion estimation co-processor architecture that explicitly separates the implementation stages consisting of data access to the search window and the evaluation of the matching criterion from the implementation of the search strategy. The architecture is modular and can be re-configured according to the different MPEG video coding profiles and level parameters. Although the architectural solutions described here can be in principle applied to any SoC implementation technologies, the solution presented here is expressly conceived and validated on FPGA co- processing architectures supporting mixed SW/HW implementations of video encoders such as generic PC platforms with a standard PCMCIA FPGA cards. The module has been developed in the framework of the MPEG reference hardware description activity.","Title: Optimization of portable parallel signal processing applications by design space exploration of dataflow programs\nYear: 2011\n\nAbstract: This paper describes a methodology for the optimization of portable parallel signal processing applications specified by dataflow programs. The use of dataflow as a programming model for signal processing applications targeting parallel platforms provides an important advantage versus the traditional sequential programming paradigm: the portability of parallelism. The paper introduce a design space exploration methodology for exploring alternative implementations in which abstract traces of a program, representing the actual data dependencies of its parts, are first constructed and then analyzed to guide the refactoring and mapping and of the signal processing applications to best match its intended parallel target. The methodology is demonstrated and evaluated in an at-size case study of an MPEG-4 video decoder.","Title: Scheduling of dynamic dataflow programs based on state space analysis\nYear: 2012\n\nAbstract: Compile-time scheduling of dynamic dataflow programs is still an open problem. This paper presents how scheduling of dynamic portions of asynchronous dataflow networks described using CAL language can be determined before execution by the analysis of the state space of network partitions. Experiments show that the number of run-time operations employed by dynamic schedulers is largely reduced when the schedules extracted by the state analysis are employed.","Title: High level design space exploration of RVC codec specifications for multi-core heterogeneous platforms\nYear: 2010\n\nAbstract: Nowadays, the design flow of complex signal processing embedded systems starts with a specification of the application by means of a large and sequential program (usually in C/C++). As we are entering in the multicore era, sequential programs are no longer the most appropriate way to specify algorithms targeted to run on several processing units. The new ISO/MPEG Reconfigurable Video Coding (RVC) standard is proposing a new paradigm for specifying and designing complex signal processing systems. The RVC standard enables specifying new codecs by assembling blocks, or so called Functional Units (FUs) from a standard Video Tool Library (VTL). Flexibility, reusability, and modularity are the key features of RVC. This new way of specifying algorithms clearly simplifies the task of designing future video coding applications by allowing software and hardware reuse across multiple video coding standards. Specifications are provided in the form of an actor and dataflow-based language called CAL. Although the RVC standard does not imply any specific implementation design flow, it is an appropriate starting point for targeting multiple processing units platforms. This paper describes a new model-driven design flow which considers both algorithm and architecture to map RVC codec specifications onto heterogeneous and multi-core systems.","Title: Systems design space exploration by serial dataflow program execution\nYear: 2013\n\nAbstract: The increasing ubiquity of heterogeneous parallel computing platforms nowadays creates the challenge to fully exploit the available computational power when porting existing programs or developing new applications with portability in mind. Existing design space exploration methods focus on specialized applications amenable to compile-time analysis. Real-world applications, however, tend to exhibit complex behavior that depends on input data and even timing. This paper proposes a methodology for creating a finite (approximate) representation of the design space of general streaming applications, based on detailed tracking of a serial run of the program. Homotopy theoretic methods are used to demonstrate how the design space of a program can be reconstructed from its serial execution trajectory. Moreover, the concept of a dependency graph of a dataflow program defined in the literature is extended with the definition of two new kinds of dependencies - the Guard Enable and Disable - and the 3-tuple notion needed to represent them.","Title: Buffer optimization based on critical path analysis of a dataflow program design\nYear: 2013\n\nAbstract: The trade-off between throughput and memory constraints is a common design problem in embedded systems, and especially for streaming applications, where the memory in question usually occurs in the form of buffers for streams of data. This paper presents a methodology, based on the post-processing of dataflow execution traces, that enables designers to make principled choices in the design space for arbitrary streaming applications in a scalable manner. It significantly extends the class of applications over traditional compile-time-only techniques, and effectively enables designers to find a close-to-minimum solution for this NP-complete problem. A heuristic algorithm exploring different buffer size configurations lets designers choose appropriate alternatives and enables them to rapidly navigate the design space. Methodology and experimental results are demonstrated in an at-size scenario using a real-world MPEG-4 SP decoder.","Title: Dataflow program analysis and refactoring techniques for design space exploration: MPEG-4 AVC/H.264 decoder implementation case study\nYear: 2013\n\nAbstract: This paper presents a methodology to perform design space exploration of complex signal processing systems implemented using the CAL dataflow language. In the course of space exploration, critical path in dataflow programs is first presented, and then analyzed using a new strategy for computational load reduction. These techniques, together with detecting design bottlenecks, point to the most efficient optimization directions in a complex network. Following these analysis, several new refactoring techniques are introduced and applied on the dataflow program in order to obtain feasible design points in the exploration space. For a MPEG-4 AVC/H.264 decoder software and hardware implementation, the multi-dimensional space can be explored effectively for throughput, resource, and frequency, with real-time decoding range from QCIF to HD resolutions.","Title: Modeling control tokens for composition of CAL actors\nYear: 2013\n\nAbstract: Dataflow programming is typically used as an intuitive representation for describing multimedia and signal processing applications as computation nodes which communicate through FIFO queues. To run a dataflow network, consisting of several nodes, either run-time or compile-time scheduling is required. Compile-time scheduling techniques are typically based on token rates between nodes and for languages such as CAL, which are expressive enough to describe an actor with any behavior, run-time scheduling is needed in the general case, introducing an overhead. However, the well defined structure of dataflow programs enables analysis of the dependencies of the program and partitions with piecewise static schedules can be derived. In this paper we describe how actor partitions with control tokens can be modeled such that a correct scheduler, where most scheduling decisions are taken at compile-time, can be derived for the resulting composed actor.","Title: Turnus: A unified dataflow design space exploration framework for heterogeneous parallel systems\nYear: 2013\n\nAbstract: This paper presents the main features of the TURNUS co-exploration environment, an unified design space exploration framework suitable for heterogeneous parallel systems designed using an high level dataflow representation. The main functions of this tool are illustrated through the analysis of a video decoder implemented in the RVC-CAL dataflow language.","Title: A Methodology For Profiling And Partitioning Stream Programs On Many-Core Architectures\nYear: 2015\n\nAbstract: Maximizing the data throughput is a very common implementation objective for several streaming applications. Such task is particularly challenging for implementations based on many-core and multi-core target platforms because, in general, it implies tackling several NP-complete combinatorial problems. Moreover, an efficient design space exploration requires an accurate evaluation on the basis of dataflow program execution profiling. The focus of the paper is on the methodology challenges for obtaining accurate profiling measures. Experimental results validate a many-core platform built by an array of Transport Triggered Architecture processors for exploring the partitioning search space based on the execution trace analysis.","Title: Execution Trace Graph Based Multi-Criteria Partitioning Of Stream Programs\nYear: 2015\n\nAbstract: One of the problems proven to be NP-hard in the field of many-core architectures is the partitioning of stream programs. In order to maximize the execution parallelism and obtain the maximal data throughput for a streaming application it is essential to find an appropriate actors assignment. The paper proposes a novel approach for finding a close-to-optimal partitioning configuration which is based on the execution trace graph of a dataflow network and its analysis. We present some aspects of dataflow programming that make the partitioning problem different in this paradigm and build the heuristic methodology on them. Our optimization criteria include: balancing the total processing workload with regards to data dependencies, actors idle time minimization and reduction of data exchanges between processing units. Finally, we validate our approach with experimental results for a video decoder design case and compare them with some state-of-the-art solutions.","Title: Execution trace graph analysis of dataflow programs: Bounded buffer scheduling and deadlock recovery using model predictive control\nYear: 2014\n\nAbstract: Execution trace graph analysis of dataflow programs has been demonstrated to be an effective way for exploring and optimizing the design space of many core applications. In this work a novel transformation from the execution trace graph to an event driven linear system is proposed. It is also illustrated how the trace space of can be effectively reduced and well known system control techniques can be efficiently used in order to find close to optimal solutions. In particular, the problem of finding a bounded buffer size configuration is proposed and solved using a model predictive controller. Two design examples, a JPEG and an MPEG HEVC decoder have been used to demonstrate the effectiveness of the approach.","Title: TURNUS: An open-source design space exploration framework for dynamic stream programs\nYear: 2014\n\nAbstract: Although the research on the design of heterogeneous concurrent systems has a long and rich history, a unified design methodology and tool support have not emerged so far. Therefore, the creation of such systems remains a difficult, time-consuming and error-prone process. The absence of principled support for system evaluation and optimization at high level of abstraction makes the quality of the resulting implementation strongly dependent on the experience or individual preferences of the designer. In this work we are presenting TURNUS, a unified dataflow design space exploration framework for heterogeneous parallel systems. This open source framework represents a decade of research on high-level modelling and simulation methods and tools for system level performance estimation and optimization. Last year we presented heuristic algorithms that were focused on the results of exploration in terms of algorithmic optimization, rapid performance estimation, application throughput, buffer size dimensioning and power optimization. This year we are presenting the novelties that have been introduced in TURNUS such as clock gating, pipelining optimization, kernel splitting algorithms, advanced partitioning algorithms and scheduling optimization based on model predictive control techniques.","Title: Tabu Search for Partitioning Dynamic Dataflow Programs.\nYear: 2016\n\nAbstract: An important challenge of dataflow programming is the problem of partitioning dataflow components onto a target architecture. A common objective function associated to this problem is to find the maximum data processing throughput. This NP-complete problem is very difficult to solve with high quality close-to-optimal solutions for the very large size of the design space and the possibly large variability of input data. This paper introduces four variants of the tabu search metaheuristic expressly developed for partitioning components of a dataflow program. The approach relies on the use of a simulation tool, capable of estimating the performance for any partitioning configuration exploiting a model of the target architecture and the profiling results. The partitioning solutions generated with tabu search are validated for consistency and high accuracy with experimental platform executions.","Title: A Partition Scheduler Model for Dynamic Dataflow Programs.\nYear: 2016\n\nAbstract: The definition of an efficient scheduling policy is an important, difficult and open design problem for the implementation of applications based on dynamic dataflow programs for which optimal closed-form solutions do not exist. This paper describes an approach based on the study of the execution of a dynamic dataflow program on a target architecture with different scheduling policies. The method is based on a representation of the execution of a dataflow program with the associated dependencies, and on the cost of using scheduling policy, expressed as a number of conditions that need to be verified to have a successful execution within each partition. The relation between the potential gain of the overall execution satisfying intrinsic data dependencies and the runtime cost of finding an admissible schedule is a key issue to find close-to-optimal solutions for the scheduling problem of dynamic dataflow applications.","Title: Performance Estimation Based Multicriteria Partitioning Approach for Dynamic Dataflow Programs\nYear: 2016\n\nAbstract: AbstractThe problem of partitioning a dataflow program onto a target architecture is a difficult challenge for any application design. In general, since the problem is NP-complete, it consists of looking for high quality solutions in terms of maximizing the achievable data throughput. The difficulty is given by the exploration of the design space which results in being extremely large for parallel platforms. The paper describes a heuristic partitioning methodology applicable to dynamic dataflow programs. The methodology is based on two elements: an execution model of the dynamic dataflow program which is used as estimation of the performance for the exploration of the large design space and several partitioning algorithms competing to lead to specific high quality solutions. Experimental results are validated with executions on a virtual platform.","Title: An Evaluation Framework for Lossy Compression of Genome Sequencing Quality Values\nYear: 2016\n\nAbstract: This paper provides the specification and an initial validation of an evaluation framework for the comparison of lossy compressors of genome sequencing quality values. The goal is to define reference data, test sets, tools and metrics that shall be used to evaluate the impact of lossy compression of quality values on human genome variant calling. The functionality of the framework is validated referring to two state-of-the-art genomic compressors. This work has been spurred by the current activity within the ISO/IEC SC29/WG11 technical committee (a.k.a. MPEG), which is investigating the possibility of starting a standardization activity for genomic information representation.","Title: Performance estimation of program partitions on multi-core platforms\nYear: 2016\n\nAbstract: The exploration of different design configurations of dynamic dataflow programs executed on many-core or multi-core platforms is, in general, a very difficult task. Determining a close-to-optimal partitioning, scheduling and buffer dimensioning configuration, when associated with a performance optimization function, belongs to the class of NP-complete problems. In order to explore the space of feasible solutions with efficient heuristics looking for solutions of good quality, it is important to be able to evaluate the design points in terms of the performance optimization function with sufficient precision without having to physically execute the program on the platform. This paper presents a performance estimation approach and an associated SW tool capable of exploring, with a high level of accuracy, the space of feasible solutions by using only a limited set of measurements from the physical processing platform. Moreover, the estimation model allows an identification of possible improvements that can be applied to different configurations. The results reported validate the accuracy of the methodology using examples of dataflow implementations of dynamic video codec designs for two different classes of platforms: Transport Triggered Architecture and Intel platforms.","Title: High-level synthesis of dynamic dataflow programs on heterogeneous MPSoC platforms\nYear: 2016\n\nAbstract: The growing complexity of digital signal processing applications make a compelling case the use of high-level design and synthesis methodologies for the implementation on programmable logic devices and embedded processors. Past research has shown that, for complex systems, raising the level of abstraction of design stages does not necessarily come at a penalty in terms of performance or resource requirements. Dataflow programs provide behavioral descriptions capable of expressing both sequential and parallel components of application algorithms and enable natural design abstractions, modularity, and portability. In this paper, an open source tool, implementing dataflow programs onto embedded heterogeneous platforms by means of high-level synthesis, software synthesis and interface synthesis is presented Experimental design results demonstrate the capability and the effectiveness of the tool for implementing a wide range of applications when combined with Vivado HLS.","Title: High-Precision Performance Estimation of Dynamic Dataflow Programs\nYear: 2016\n\nAbstract: An important challenge for a dataflow designer is to efficiently explore the design space in order to find a set of configurations that satisfy the defined objective function. The exploration directions may involve the partitioning, scheduling and buffer dimensioning, and all together should drive the designer to maximally benefit from the potential parallelism of an application. Successful exploration can be strongly facilitated by means of performance estimation. This paper presents a tool that allows a high-precision estimation of a program execution on a given platform, when various sets of configurations can be applied. It demonstrates which information related to the multi-core program execution can be extracted and successfully used to drive the optimization procedures. The experimental results are confirmed by an actual execution on different types of platforms.","Title: Clock-Gating of Streaming Applications for Energy Efficient Implementations on FPGAs.\nYear: 2017\n\nAbstract: This paper investigates the reduction of dynamic power for streaming applications yielded by asynchronous dataflow designs by using clock gating techniques. Streaming applications constitute a very broad class of computing algorithms in areas such as signal processing, digital media coding, cryptography, video analytics, network routing, packet processing, etc. This paper introduces a set of techniques that, considering the dynamic streaming behavior of algorithms, can achieve power savings by selectively switching off parts of the circuits when they are temporarily inactive. The techniques being independent from the semantic of the application can be applied to any application and can be integrated into the synthesis stage of a high-level dataflow design flow. Experimental results of at-size applications synthesized on field-programmable gate arrays platforms demonstrate power reductions achievable with no loss in data throughput.","Title: On the Development and Optimization of HEVC Video Decoders Using High-Level Dataflow Modeling.\nYear: 2017\n\nAbstract: With the emergence of the High Efficiency Video Coding (HEVC) standard, a dataflow description of the decoder part was developed as part of the MPEG-B standard. This dataflow description presented modest framerate results which led us to propose methodologies to improve the performance. In this paper, we introduce architectural improvements by exposing more parallelism using YUV and frame-based parallel decoding. We also present platform optimizations based on the use of SIMD functions and cache efficient FIFOs. Results show an average acceleration factor of 5.8 in the decoding framerate over the reference architecture.","Title: Differential Gene Expression with Lossy Compression of Quality Scores in RNA-Seq Data\nYear: 2017\n\nAbstract: High-throughput sequencing of RNA molecules has enabled the quantitative analysis of the expression of genes at the expense of storage space and processing power. To help alleviate these problems, lossy compression methods of the quality scores associated to RNA sequence data have recently been proposed, and the evaluation of their impact on downstream analysis is gaining attention. This work presents a first assessment of the impact of lossly compressed quality scores in RNA sequence data on the performance of some of the most recent tools used for differential gene expression.","Title: High-level system synthesis and optimization of dataflow programs for MPSoCs\nYear: 2016\n\nAbstract: The growing complexity of digital signal processing applications make a compelling case the use of high-level design and synthesis methodologies for the implementation on reconfigurable and embedded devices. Past research has shown that raising the level of abstraction of design stages does not necessarily gives penalties in terms of performance or resources. Dataflow programs provide behavioral descriptions capable of expressing both sequential and parallel algorithms and enable natural design abstractions, modularity, and portability. In this paper, a tool implementing dataflow programs onto embedded heterogeneous platforms by means of high-level synthesis, software synthesis and interface synthesis is presented for MPSoCs platfroms.","Title: Trace-based manycore partitioning of stream-processing applications\nYear: 2016\n\nAbstract: Application performance on these processor array platforms is highly sensitive to how functionality is physically placed on the device, as this choice crucially determines communication latencies and congestion patterns of the on-chip inter-core communication. The problem of identifying the best, or just a good enough, partitioning and placement does not, in general, admit to an analytic solution, and its combinatorial nature makes solving it by pure experimentation impractical. This paper presents an approach that maps stream programs onto processor arrays using trace analysis as a technique for evaluating candidate solutions and for suggesting alternatives.","Title: Buffer dimensioning for throughput improvement of dynamic dataflow signal processing applications on multi-core platforms.\nYear: 2017\n\nAbstract: Executing a dataflow program on a parallel platform requires assigning to each buffer a given size so that correct program executions take place without introducing any deadlock. Furthermore, in the case of dynamic dataflow programs, specific buffer size assignments lead to significant differences in the throughput, hence a more appropriate optimization problem is to specify the buffer sizes so that the throughput is maximized and the used resources are minimized. This paper introduces a new heuristic methodology for the buffer dimensioning of dynamic dataflow programs, which is considered as a stage of a more general design space exploration process.","Title: Design Space Exploration Of Dataflow-Based Smith-Waterman Fpga Implementations\nYear: 2017\n\nAbstract: The paper presents the results of design space explorations for the implementation of the Smith-Waterman (S-W) algorithm performing DNA and protein sequences alignment. Both design explorations studies and FPGA implementations are obtained by developing a dynamic dataflow program implementing the algorithm and by direct high-level synthesis (HLS) to FPGA HDL. The main feature of the obtained implementation is a low-latency, pipelinable multistage processing element (PE), providing a substantial decrease in resource utilization and increase in computation throughput when compared to state of the art solutions. The implementation solution is also fully scalable and can be efficiently reconfigured according to the DNA sequence sizes and performance requirements of the system architecture. The implementation solution presented in the paper can efficiently scale up to 250MHz obtaining 14746 Alignments/s using a single S-W core with 4 PEs, and up to 31.8 MegaAlignments/min using 36 S-W cores on the same FPGA for sequences of 160 x 100 nucleotides.","Title: Lossy Compression of Quality Scores in Differential Gene Expression: A First Assessment and Impact Analysis\nYear: 2018\n\nAbstract: High-throughput sequencing of RNA molecules has enabled the quantitative analysis of gene expression at the expense of storage space and processing power. To alleviate these problems, lossy compression methods of the quality scores associated to RNA sequencing data have recently been proposed, and the evaluation of their impact on downstream analyses is gaining attention. In this context, this work presents a first assessment of the impact of lossily compressed quality scores in RNA sequencing data on the performance of some of the most recent tools used for differential gene expression.","Title: High-Precision Performance Estimation for the Design Space Exploration of Dynamic Dataflow Programs.\nYear: 2018\n\nAbstract: The implementation and optimization of dynamic dataflow programs on multi/many-core platforms require solving a very difficult problem: how to partition and schedule the processing elements and dimension their interconnecting buffers according to given optimization functions in terms of throughput, memory usage, and energy consumption. This problem is NP-hard even for two cores. Thus, finding a cl...","Title: Execution Trace Graph of Dataflow Process Networks.\nYear: 2018\n\nAbstract: The paper introduces and specifies a formalism that provides complete representations of dataflow process network (DPN) program executions, by means of directed acyclic graphs. Such graphs, also known as execution trace graphs (ETG), are composed of nodes representing each action firing and by directed arcs representing the dataflow program execution constraints between two action firings. Action ...","Title: Shared-variable Synchronization Approaches for Dynamic Data Flow Programs\nYear: 2018\n\nAbstract: This paper presents shared-variable synchronization approaches for dataflow programming. The mechanisms do not require any substantial model of computation (MoC) modifi-cation, and is portable across both for hardware (HW) and software (SW) low-level code synthesis. With the shared-variable formalization, the benefits of the dataflow MoC are maintained, however the space and energy efficiency of an application can be significantly improved. The approach targets Dynamic Process Network (DPN) dataflow applications, thus making them also suitable for less expressive models e.g. synchronous and cyclo-static dataflow that DPN subsumes. The approach is validated through the analysis and optimization of a High-Efficiency Video Coding (HEVC) decoder implemented in the RVC-CAL dataflow language targeting a multi-core platform. Experimental results show how, starting from an initial design that does not use the shared-variable formalism, frames per second throughput performance is increased by a factor of 21.","Title: Efficient Dynamic Optimisation Heuristics for Dataflow Pipelines\nYear: 2018\n\nAbstract: Large dataflow designs appear as a result of functional specification of modern complex digital systems and/or a result of unfolding and behavioral transformation of looped and branched programs. Since deep-submicron silicon technology provides large amounts of available resources, pipelining optimization without resource sharing can give significant advantages in performance. In this work, we propose a novel pipeline optimization heuristic algorithm, which is named HADD. It is suitable for very large dataflow programs and makes use of efficient dynamic heuristics and a random search on the set of solutions. For a pipeline-stage time-period, it quickly minimizes the number of stages and successively finds the assignment of operators to stages with the objective of minimizing the overall pipeline registers size. The experimental results show that HADD gives solutions that are very close to accurate solutions with only 2% of the difference and overcomes by about 10% on average the best-known heuristic technique HT, which uses mixed static-dynamic heuristics on large designs. Moreover, HADD is c.a. 10 times faster on average against HT.","Title: An Heterogeneous Compiler Of Dataflow Programs For Zynq Platforms\nYear: 2019\n\nAbstract: In recent years, the number and variety of heterogeneous multiprocessor system-on-chip MPSoCs, such as for instance Zynq platforms, has sensibly increased. However, today all design flow solutions capable of programming the different components of such platforms require to the designer either to modify the software or hardware based designs to obtain higher performance implementations. Thus, the developer needs to either rewrite functional blocks in HDL or to use high-level synthesis of C-like sequential languages with platform locked extensions. In this paper, a compiler infrastructure that takes as input a single behavioral representation, expressed in high-level dataflow RVC-CAL language, is proposed for programming any of the components of heterogeneous Zynq MPSoCs platforms without the need of modifying any line of code on the design.","Title: Composite Data Types In Dynamic Dataflow Languages As Copyless Memory Sharing Mechanism\nYear: 2019\n\nAbstract: This paper presents new optimization approaches aiming at reducing the impact of memory accesses on the performance of dataflow programs. The approach is based on introducing a high level management of composite data types in dynamic dataflow programming language for the memory processing of data tokens. It does not require essential changes to the model of computation (MOC) or to the dataflow program itself. The objective of the approach is to remove the unnecessary constraints of memory isolations without introducing limitations to the scalability and composability properties of the dataflow paradigm. Thus the identified optimizations allow to keep the same design and programming philosophy of dataflow, whereas aiming at improving the performance of the specific configuration implementation. The different optimizations can be integrated into the current RVC-CAL design flows and synthesis tools and can be applied to different sub-networks partitions of the dataflow program. The paper introduces the context, the definition of the optimization problem and describes how it can be applied to dataflow designs. Some examples of the optimizations are provided.","Title: An Introduction to MPEG-G: The First Open ISO/IEC Standard for the Compression and Exchange of Genomic Sequencing Data\nYear: 2021\n\nAbstract: The development and progress of high-throughput sequencing technologies have transformed the sequencing of DNA from a scientific research challenge to practice. With the release of the latest generation of sequencing machines, the cost of sequencing a whole human genome has dropped to less than $\\$ $ 600. Such achievements open the door to personalized medicine, where it is expected that genomic information of patients will be analyzed as a standard practice. However, the associated costs, related to storing, transmitting, and processing the large volumes of data, are already comparable to the costs of sequencing. To support the design of new and interoperable solutions for the representation, compression, and management of genomic sequencing data, the Moving Picture Experts Group (MPEG) jointly with working group 5 of ISO/TC276 “Biotechnology” has started to produce the ISO/IEC 23092 series, known as MPEG-G. MPEG-G does not only offer higher levels of compression compared with the state of the art but it also provides new functionalities, such as built-in support for random access in the compressed domain, support for data protection mechanisms, flexible storage, and streaming capabilities. MPEG-G only specifies the decoding syntax of compressed bitstreams, as well as a file format and a transport format. This allows for the development of new encoding solutions with higher degrees of optimization while maintaining compatibility with any existing MPEG-G decoder.","Title: A 0.4 nJ Excitation Energy Bridge-to-Digital Converter for Implantable Pulmonary Artery Pressure Monitoring\nYear: 2021\n\nAbstract: This paper presents an energy-efficient, duty-cycled, and spinning excitation bridge-to-digital converter (BDC) suitable for measuring the pulmonary artery pressure of heart failure patients with an implantable system. The duty-cycled bridge uses resistances of 6.2 kΩ and, with a supply of 1.2 V, consumes 0.4 nJ excitation energy. A novel spinning method is applied to the bridge and the capacitive...","Title: Performance Estimation of High-Level Dataflow Program on Heterogeneous Platforms\nYear: 2021\n\nAbstract: The performance of programs written in languages following the dataflow model of computation (MoC) largely depends on the configuration (partitioning, mapping, scheduling, buffer dimensioning) chosen during the synthesis stages. Furthermore, this programming paradigm is particularly well suited for heterogeneous parallel systems because it is inherently free of memory contention and exposes parallel opportunities. Both of these statements show the necessity for a way to easily and automatically evaluate and find good design configurations. The paper describes the methodology required for clock-accurate profiling of high-level dataflow programs written in RVL-CAL when synthesized on heterogeneous CPU/GPU co-processing platforms. It also extends to the heterogeneous paradigm an existing methodology for qualitatively estimating the performance of such programs as a function of the provided configuration. This, without the need to synthesize and profile every single configuration on the actual hardware platform. This approach is validated using two application programs and several configurations.","Title: SIMD Parallel Execution on GPU from High-Level Dataflow Synthesis\nYear: 2021\n\nAbstract: Writing and optimizing application software for heterogeneous platforms including GPU units is a very difficult task that requires designer efforts and resources to consider several key elements to obtain good performance. Dataflow programming has shown to be a good approach for accomplishing such a difficult task for its properties of portability and the possibility of arbitrary partitioning a dataflow network on each unit of heterogeneous platforms. However, such a design methodology is not sufficient by itself to obtain good performance. The paper describes some methodological steps for improving the performance of dataflow programs written in RVC-CAL and synthesized to execute on heterogeneous CPU/GPU co-processing platforms. The steps do include the optimization of the performance of the communication tasks between processing elements, a strategy for the efficient scheduling of independent GPU partitions, and the introduction of dynamic programming for leveraging the SIMD nature of GPU platforms. The approach is validated qualitatively and quantitatively using dataflow application program examples executed by applying several partitioning configurations.","Title: Methodologies for Synthesizing and Analyzing Dynamic Dataflow Programs in Heterogeneous Systems for Edge Computing\nYear: 2021\n\nAbstract: The possibility of using the increasing computing power available in cloud infrastructures requires the development of new approaches for application software development and optimization. Emerging edge computing paradigms offer the possibility of reducing bandwidth needs and of optimizing latency, features particularly relevant for Big Data applications, by bringing computation closer to the user and to the data generation processes. However, edge computing approaches pose several challenges in terms of how to be able to efficiently take advantage of a distributed network of heterogeneous processing nodes. This paper deals with this problem by extending a dynamic dataflow software development framework and related design flow tools to support heterogeneous platforms. The paper describes the methodology steps for the synthesis of application software executing on heterogeneous CPU/GPU co-processing nodes. The steps do include the optimization of the communication between heterogeneous processing elements, a technique for the efficient mapping and parallelization of computation on independent GPU partitions, and the introduction of dynamic programming approach for leveraging the SIMD nature of GPU computing. To complete the methodology of seamless porting of dataflow software and partition on CPU or GPU computing nodes, an automated methodology for exploring the configuration space and to identify high performance working points is developed.","Title: The impact of NFT profile pictures within social network communities.\nYear: 2022\n\nAbstract: This paper presents an analysis of the role of social media, specifically Twitter, in the context of non-fungible tokens, better known as NFTs. Such emerging technology framing the creation and exchange of digital object, started years ago with early projects such as \"CryptoPunks\" and since early 2021, has received an increasing interest by a community of people creating, buying, selling NFT's and by the media reporting to the general public. In this work it is shown how the landscape of one class of projects, specifically those used as social media profile pictures, has become mainstream with leading projects such as \"Bored Ape Yacht Club\", \"Cool Cats\" and \"Doodles\". This work illustrates how heterogeneous data was collected from the Ethereum blockchain and Twitter and then analysed using algorithms and state-of-art metrics related to graphs. The initial results show that from a social network perspective, the collections of most popular NFTs can be considered as a single community around NFTs. Thus, while each project has its own value and volume of exchange, on a social level all of them are primarily influenced by the evolution of values and trades of \"Bored Ape Yacht Club\" collection.","Title: A Benchmark of Entropy Coders for the Compression of Genome Sequencing Data\nYear: 2022\n\nAbstract: Genomic sequencing data contain three different data fields: read names, quality values, and nucleotide sequences. In this work, a variety of entropy encoders and com-pression algorithms were benchmarked in terms of compression-decompression rates and times separately for each data field as raw data from FASTQ files (implemented in the Fastq analysis script) and in MPEG-G uncompressed descriptor symbols de-coded from MPEG-G bitstreams (implemented in the symbols analysis script). The result of this benchmark is then compared to the performance of CABAC, which is the encoder used in first edition of the ISO /IEC MPEG-G standard for all types of descriptors, since CABAC was the best performing in terms of compression rates for the three types of data, thus providing overall better compression rates compared to other entropy coders in total. However, in some use cases encoding and decoding speed might be of higher interest than compression, and for specific datasets, types of data, or descriptor streams, other entropy coders might provide higher speed and/or better compression performance than CABAC.","Title: MPEG-G Reference-Based Compression of Unaligned Reads Through Ultra-Fast Alignments\nYear: 2022\n\nAbstract: With the widespread application of next generation sequencing technologies, the volume of sequencing data became comparable to that of big data domains. The compression of sequencing reads (nucleotide sequences, quality values, read names), in both raw and aligned data, is a way to alleviate bandwidth, transfer, and storage requirements of genomics pipelines. ISO/IEC MPEG-G standardizes the compressed representation (i.e. storage and streaming) of structured, indexed sets of genomic sequencing data for both raw and aligned data. For the latter, reference-based compression is a strategy used to compress nucleotide sequences of sequencing reads by using alignment information to a reference sequence, which can be used to represent nucleotide sequences by storing the starting position of the alignment on the reference sequence, and the differences between the reference and the actual read. This general scheme is implemented in different ways by genomic data compressors, such as DeeZ, Quip, and CRAM, which apply to aligned reads.","Title: A Capacitively-Coupled Chopper Instrumentation Amplifier for Implantable Bridge Sensor Systems\nYear: 2022\n\nAbstract: This paper presents an energy and area efficient capacitively-coupled chopper instrumentation amplifier (CCIA) dedicated to implantable bridge sensor systems. Chopper stabilization is employed to decrease its offset and 1/f noise and the resulting ripple due to the up-modulated offset and 1/f noise is suppressed by a switched-capacitor ripple reduction loop. The gain of the instrumentation amplifier is defined by a programmable capacitive feedback network with a gain range from 40 V/V to 116 V/V, which is suitable for use with bridge sensors having different output voltages. The proposed CCIA has been fabricated in a standard 0.18 µm CMOS process. It achieves an input noise of 88.2 nV/√Hz, a worst-case input offset of 5 µV, and an output ripple of less than 185 μV. The CCIA occupies only 0.17 mm\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sup>\n chip area and draws 3.3 μA current from a 1.2 V supply."],"string":"[\n \"Title: Algorithm/architecture co-exploration of visual computing on emergent platforms: overview and future prospects\\nYear: 2009\\n\\nAbstract: Concurrently exploring both algorithmic and architectural optimizations is a new design paradigm. This survey paper addresses the latest research and future perspectives on the simultaneous development of video coding, processing, and computing algorithms with emerging platforms that have multiple cores and reconfigurable architecture. As the algorithms in forthcoming visual systems become increasingly complex, many applications must have different profiles with different levels of performance. Hence, with expectations that the visual experience in the future will become continuously better, it is critical that advanced platforms provide higher performance, better flexibility, and lower power consumption. To achieve these goals, algorithm and architecture co-design is significant for characterizing the algorithmic complexity used to optimize targeted architecture. This paper shows that seamless weaving of the development of previously autonomous visual computing algorithms and multicore or reconfigurable architectures will unavoidably become the leading trend in the future of video technology.\",\n \"Title: A Parallel Multimedia Processor For Macroblock Based Compression Standards\\nYear: 1997\\n\\nAbstract: This paper presents a multimedia processor based on a SIMD architecture optimized for block based video processing algorithms.The processor, called DGP (Digital Generic Processor), is a generic system architecture, constituted by an array of pixel processors (SIMD) and a RISC controller. It is able to execute various video processing algorithms such as digital filtering, video effects, window clipping, and to perform video compression according to standards such as H.261, H.263, MPEG-1 and MPEG-2. The processor can be programmed in order to run the code corresponding to each specific algorithm.\",\n \"Title: Reconfigurable video coding: objectives and technologies\\nYear: 2009\\n\\nAbstract: The main objective of the MPEG Reconfigurable Video Coding (RVC) standard is to establish a framework for a more flexible usage of standard video coding technology. The framework not only supports multiple standards and new coding configurations, but also provides an incremental and modular approach to innovation in video compression development and design. This paper provides an overview of the main objectives of RVC, standard accompanied with a presentation of the components of the framework for both normative parts and supporting tools useful for the final implementation of RVC codecs. These elements include: the Video Tool Library (VTL), the new standard RVC-CAL language used for the specification of the library, the Bitstream Syntax Description (BSD) used for the specification of the compressed bitstreams, as well as the Functional unit Network Description (FND) that constitutes the specification of a modular library. Technologies and tools that support the RVC standard are also briefly introduced.\",\n \"Title: Hardware and software synthesis of heterogeneous systems from dataflow programs\\nYear: 2012\\n\\nAbstract: The new generation of multicore processors and reconfigurable hardware platforms provides a dramatic increase of the available parallelism and processing capabilities. However, one obstacle for exploiting all the promises of such platforms is deeply rooted in sequential thinking. The sequential programming model does not naturally expose potential parallelism that effectively permits to build parallel applications that can be efficiently mapped on different kind of platforms. A shift of paradigmis necessary at all levels of application development to yield portable and scalable implementations on the widest range of heterogeneous platforms. This paper presents a design flow for the hardware and software synthesis of heterogeneous systems allowing to automatically generate hardware and software components as well as appropriate interfaces, from a unique high-level description of the application, based on the dataflow paradigm, running onto heterogeneous architectures composed by reconfigurable hardware units and multicore processors. Experimental results based on the implementation of several video coding algorithms onto heterogeneous platforms are also provided to show the effectiveness of the approach both in terms of portability and scalability.\",\n \"Title: A Simplified 8 × 8 Transformation and Quantization Real-Time IP-Block for MPEG-4 H.264/AVC Applications: a New Design Flow Approach\\nYear: 2007\\n\\nAbstract: Current multimedia design processes suffer from the excessively large time spent on testing new IP-blocks with references based on large video encoders specifications ( usually several thousands lines of code). The appropriate testing of a single IP-block may require the conversion of the overall encoder from software to hardware, which is dificult to complete in the short time required by the competition-driven reduced time-to-market demanded for the adoption of a new video coding standard. This paper presents a new design flow to accelerate the conformance testing of an IP-block using the H. 264/AVC software reference model. An example block of the simplified 8 x 8 transformation and quantization, which is adopted in FRExt, is provided as a case study demonstrating the effectiveness of the approach.\",\n \"Title: Reconfigurable video coding: a stream programming approach to the specification of new video coding standards\\nYear: 2010\\n\\nAbstract: Current video coding standards, and their reference implementations, are architected as large monolithic and sequential algorithms, in spite of the considerable overlap of functionality between standards, and the fact that they are frequently implemented on highly parallel computing platforms. The former leads to unnecessary complexity in the standardization process, while the latter implies that implementations have to be rebuilt from the ground up to reflect the parallel nature of the target. The upcoming Reconfigurable Video Coding (RVC) standard currently developed at MPEG attempts to address these issues by building a framework that supports the construction of video standards as libraries of coding tools. These libraries can be incrementally updated and extended, and the tools in them can be aggregated to form complete codecs using a streaming (or dataflow) programming model, which preserves the inherent parallelism of the coding algorithm. This paper presents the RVC framework and its underlying data flow programming model, along with the tool support and initial results.\",\n \"Title: Static and quasi-static compositions of stream processing applications from dynamic dataflow programs.\\nYear: 2013\\n\\nAbstract: Dynamic dataflow models for their expressiveness properties have shown to represent more adequate and attractive solutions for describing state of the art signal processing applications. However, they are known to present potential run-time penalties when implementations are obtained by mapping and scheduling a dataflow network partition on a processing unit. In general terms, a completely static scheduling at compile-time of dynamic dataflow programs remains an unsolved problem. Several approaches for the composition of actors are promising approach that can significantly reduce the potential penalty of run-time scheduling thus increasing the overall performance of the system. This paper presents static and quasi-static composition techniques that results in a reduction of the portion of dynamic dataflow networks, by applying appropriate transformations to network partitions that after a specific analysis demonstrate to possess a predictable behaviour. Some experiments based on a video processing application ported on several system-on-chips show the achievable speedup corresponding to the reduction of the number of run-time scheduling decisions.\",\n \"Title: Methodology for the hardware/software co-design of dataflow programs\\nYear: 2011\\n\\nAbstract: New generations of multi-core processors and reconfigurable hardware platforms are expected to provide a dramatic increase of processing capabilities. However, one obstacle for exploiting all the promises of such new platforms is the legacy of current applications and the development methodologies used, which is deeply rooted in a sequential way of thinking. A paradigm shift is necessary at all levels of application development to yield portable and efficient implementations, capable of exploiting the full potential of such platforms. Dataflow programming is an alternative approach that address the problem of providing portable and scalable parallel applications. Dataflow programming is able to explicitly expose the intrinsic parallelism of applications. This paper presents a hardware/software co-design methodology that starting from a unique dataflow program enables, by the direct synthesis of both hardware (HDL) and software components (C/C++), to map a signal processing application onto heterogeneous systems architectures composed by reconfigurable hardware and multi-core processors. Experimental results based on the implementation of the MPEG-4 Simple Profile decoder onto an heterogeneous platform are also provided to show the capabilities and flexibility of the approach.\",\n \"Title: Reconfigurable Media Coding: A New Specification Model for Multimedia Coders\\nYear: 2007\\n\\nAbstract: Multimedia coding technology, after about 20 years of active research, has delivered a rich variety of different and complex coding algorithms. Selecting an appropriate subset of these algorithms would, in principle, enable a designer to produce the codec supporting any desired functionality as well as any desired trade-off between compression performance and im- plementation complexity. Currently, interoperability demands that this selection process be hard-wired into the normative descriptions of the codec, or at a lower level, into a predefined number of choices, known as profiles, codified within each standard specification. This paper presents an alternative paradigm for codec deployment that is currently under development by MPEG, known as Reconfigurable Media Coding (RMC). Using the RMC framework, arbitrary combinations of fundamental al- gorithms may be assembled, without predefined standardiza- tion, because everything necessary for specifying the decoding process is delivered alongside the content itself. This side- information consists of a description of the bitstream syntax, as well as a description of the decoder configuration. Decoder configuration information is provided as a description of the interconnections between algorithmic blocks. The approach has been validated by development of an RMC format that matches MPEG-4 Video, and then extending the format by adding new chroma-subsampling patterns.\",\n \"Title: A platform for mixed HW/SW algorithm specifications for the exploration of SW and HW partitioning\\nYear: 2007\\n\\nAbstract: The increasing complexity in particular of video and multimedia processing has lead to the need of developing the algorithms specification using software implementations that become in practice generic reference implementations. Mapping directly such software models in platforms made of processors and dedicated HW elements becomes harder and harder for the complexity of the models and for the large choice of possible partitioning options. This paper describes a new platform aiming at supporting the mapping of software specifications into mixed SW and HW implementations. The platform is supported by profiling capabilities specifically conceived to study data transfers between SW and HW modules. Such optimization capabilities can be used to achieve different objectives such as optimization of memory architectures or low power designs by the minimization of data transfers.\",\n \"Title: Multimedia terminal architecture: An inter-operable approach\\nYear: 2008\\n\\nAbstract: This paper addresses the inter-operability problem of multimedia terminal in media content delivery over heterogeneous networks and devices. We design and implement a terminal which includes a content browser providing presentation, navigation and interaction with MPEG-21 Digital Item Declaration (MPEG-21 DID) in order to support universal media access (UMA). We optimized the architecture in a client-server distributed approach with Web Service support. This terminal enables the MPEG-21 standard compliant content accessible on different terminal devices via common Web browsers. Such a design strategy illustrates a next-generation multimedia terminal supporting inter-operability in multimedia content adaptation over a heterogeneous delivery chain.\",\n \"Title: Secure computing with the MPEG RVC framework\\nYear: 2013\\n\\nAbstract: Recently, ISO/IEC standardized a dataflow-programming framework called Reconfigurable Video Coding (RVC) for the specification of video codecs. The RVC framework aims at providing the specification of a system at a high abstraction level so that the functionality (or behavior) of the system become independent of implementation details. The idea is to specify a system so that only intrinsic features of the algorithms are explicitly expressed, whereas implementation choices can then be made only once specific target platforms have been chosen. With this system design approach, one abstract design can be used to automatically create implementations towards multiple target platforms. In this paper, we report our investigations on applying the methodology standardized by the MPEG RVC framework to develop secure computing in the domains of cryptography and multimedia security, leading to the conclusion that the RVC framework can successfully be applied as a general-purpose framework to other fields beyond multimedia coding. This paper also highlights the challenges we faced in conducting our study, and how our study helped the RVC and the secure computing communities benefited from each other. Our investigations started with the development of a Crypto Tools Library (CTL) based on RVC, which covers a number of widely used ciphers and cryptographic hash functions such as AES, Triple DES, ARC4 and SHA-2. Performance benchmarking results on the RVC-based AES and SHA-2 implementations in both C and Java revealed that the automatically generated implementations can achieve a comparable performance to some manually written reference implementations. We also demonstrated that the RVC framework can easily produce implementations with multi-core support without any change to the RVC code. A security protocol for mutual authentication was also implemented to demonstrate how one can build heterogeneous systems easily with RVC. By combining CTL with Video Tool Library (a standard library defined by the RVC standard), a non-standard RVC-based H.264/AVC encoder and a non-standard RVC-based JPEG codec, we further demonstrated the benefits of using RVC to develop different kinds of multimedia security applications, which include joint multimedia encryption-compression schemes, digital watermarking and image steganography in JPEG compressed domain. Our study has shown that RVC can be used as a general-purpose implementation-independent development framework for diverse data-driven applications with different complexities.\",\n \"Title: High level extraction of SoC architectural information from generic C algorithmic descriptions\\nYear: 2005\\n\\nAbstract: The complexity of nowadays, algorithms in terms of number of lines of codes and cross-relations among processing algorithms that are activated by specific input signals, goes far beyond what the designer can reasonably grasp from the \\\"pencil and paper\\\" analysis of the (software) specifications. Moreover, depending on the implementation goal different measures and metrics are required at different steps of the implementation methodology or design flow of SoC. The process of extracting the desired measures needs to be supported by appropriate automatic tools, since code rewriting, at each design stage, may result resource consuming and error prone. This paper presents an integrated tool for automatic analysis capable of producing complexity results based on rich and customizable metrics. The tool is based on a C virtual machine that allows extracting from any C program execution the operations and data-flow information, according to the defined metrics. The tool capabilities include the simulation of virtual memory architectures.\",\n \"Title: Automatic Synthesis of Parsers and Validation of Bitstreams Within the MPEG Reconfigurable Video Coding Framework\\nYear: 2011\\n\\nAbstract: Video coding technology has evolved in the past years into a variety of different and complex algorithms. So far the specifications of such standard algorithms have been done case by case, providing monolithic textual and reference software specifications, but without paying any attention to the possibility of further improvements of such monolithic standards. The MPEG Reconfigurable Video Coding (RVC) framework is a new ISO/IEC standard, currently under its final stage of development aiming at providing video codec specifications at the level of coding tools instead of monolithic descriptions. The possibility to select a subset of standard video coding algorithms to specify a decoder that satisfies application specific constraints is very attractive. However, such possibility to reconfigure codecs requires systematic procedures and tools capable of describing the new bitstream syntaxes of such new codecs. Moreover, it becomes also necessary to generate the associated parsers, capable of parsing the new bitstreams. This paper further explains the problem and describes the technologies used to describe new bitstream syntaxes. Additionally, the paper describes the methodologies and the tools for the validation of bitstream syntaxes descriptions as well as a systematic procedure for automatically synthesizing parsers from the bitstream descriptions.\",\n \"Title: High-level algorithmic complexity evaluation for system design\\nYear: 2003\\n\\nAbstract: The increasing complexity of processing algorithms has led to the need of more and more intensive specification and validation by means of software implementations. As the complexity grows, the intuitive understanding of the specific processing needs becomes harder and harder. Hence, the architectural implementation choices or the choices between different possible software/hardware partitioning become extremely difficult tasks. Moreover, it is also desirable to understand and measure the algorithm complexity at the highest possible level near to the algorithmic level so as to be able to take the more appropriate actions. Automatic tools to perform such analysis become nowadays a fundamental need.In this paper, the requirements of a suitable algorithmic complexity evaluation technology are discussed, with a particular emphasis to the problem of the analysis of multimedia systems and signal processing algorithms. A brief review about limitations and weaknesses of existing tools is given, specifying the characteristics of ideal \\\"complexity evaluation systems\\\". A new approach is described, called here Software Instrumentation Tool, SIT, yielding an automatic software tool able to extract information not depending on the simulation platform, keeping into account specific input data and resulting in a good and useful measure of the desired high-level algorithmic complexity.\",\n \"Title: Methods to explore design space for MPEG RMC codec specifications\\nYear: 2013\\n\\nAbstract: The recent MPEG Reconfigurable Media Coding (RMC) standard aims at defining media processing specifications (e.g. video codecs) in a form that abstracts from the implementation platform, but at the same time is an appropriate starting point for implementation on specific targets. To this end, the RMC framework has standardized both an asynchronous dataflow model of computation and an associated specification language. Either are providing the formalism and the theoretical foundation for multimedia specifications. Even though these specifications are abstract and platform-independent the new approach of developing implementations from such initial specifications presents obvious advantages over the approaches based on classical sequential specifications. The advantages appear particularly appealing when targeting the current and emerging homogeneous and heterogeneous manycore or multicore processing platforms. These highly parallel computing machines are gradually replacing single-core processors, particularly when the system design aims at reducing power dissipation or at increasing throughput. However, a straightforward mapping of an abstract dataflow specification onto a concurrent and heterogeneous platform does often not produce an efficient result. Before an abstract specification can be translated into an efficient implementation in software and hardware, the dataflow networks need to be partitioned and then mapped to individual processing elements. Moreover, system performance requirements need to be accounted for in the design optimization process. This paper discusses the state of the art of the combinatorial problems that need to be faced at this design space exploration step. Some recent developments and experimental results for image and video coding applications are illustrated. Both well-known and novel heuristics for problems such as mapping, scheduling and buffer minimization are investigated in the specific context of exploring the design space of dataflow program implementations.\",\n \"Title: A Multimedia Terminal Supporting Adaptation for QoS Control\\nYear: 2008\\n\\nAbstract: This paper addresses the End-to-End Quality of Service (QoS) guarantees and control for multimedia content delivery over heterogeneous networks, with a particular focus on end user terminal perspective. A multimedia terminal which embeds different probes to monitor network conditions and end user perceptual characteristics has been conceived and implemented. A series of QoS mapping between perception and adaptation spaces are yielded by means of the parameters provided by the QoS probes, facilitating content adaptation enabled by any generic adaptation server or intermediate service. Such a design approach illustrates a possible architecture for next-generation multimedia end user system supporting QoS control and content adaptation over a heterogeneous delivery chain.\",\n \"Title: Overlapped motion compensation for subband coding of video sequences\\nYear: 1996\\n\\nAbstract: Block motion compensation (MC) is widely used in hybrid coding schemes. The presence of motion discontinuities inside the blocks introduces inefficiencies that reduce the performances of MC methods. Moreover the displaced frame difference (DFD) image shows block discontinuities. This fact is the main difficulty in using block-based MC in subband coding systems. This limitation does not appear in transform-based algorithms, where the boundaries of the transform support coincide with the MC block boundaries. Overlapped window motion estimation and compensation have been proposed to overcome these limitations leading to a reduction of the DFD energy and of the blocking artifacts. Overlapped MC is eqivalent to a linear combination of predictors based on neighboring block motion vectors. In this paper we describe a motion compensation scheme with new overlapped window modes. We report the improvements achieved in terms of DFD energy reduction and block boundaries reduction. Then a complete coding system based on subband decomposition is defined to evaluate the performances of the extended MC scheme in terms of bit rate reduction, SNR, and perceived visual quality. Simulation results have shown noticeable gains of the overlapped motion compensation over the MPEG2 MC scheme used for subband coding increasing only the complexity of the MC part.\",\n \"Title: A Co-Design Platform For Algorithm/Architecture Design Exploration\\nYear: 2008\\n\\nAbstract: The efficient implementation of multimedia algorithms, for the ever increasing complexity of the specifications and the emergence of the new generation of processing platforms characterized by multicore and multicomponent parallel architectures, requires appropriate design space exploration procedures as preliminary step for any implementation. This paper describes a new platform aiming at supporting the algorithm and architecture co-exploration starting by a pure software specification that is gradually transformed into a possibly mixed SW and HW implementation. The process is based on profiling capabilities supported by the new platform specifically conceived to study and optimize data flows and data transfers between SW and HW modules. Different explicit or implicit (i.e. virtual memory extensions) data transfer modes can be profiled in the co-exploration process, by using minimal SW reconfiguration, thus minimizing any SW/HW re-writing effort in the co-exploration stage. Such optimization capabilities can be used to achieve different optimization objectives such as the optimization of memory architectures or low power designs by appropriate minimization of data transfers. Experimental results and an example of the usage of the platform are provided for the design case of a motion estimation module for video encoding.\",\n \"Title: Pipeline synthesis and optimization of FPGA-based video processing applications with CAL.\\nYear: 2011\\n\\nAbstract: This article describes a pipeline synthesis and optimization technique that increases data throughput of FPGA-based system using minimum pipeline resources. The technique is applied on CAL dataflow language, and designed based on relations, matrices, and graphs. First, the initial as-soon-as-possible (ASAP) and as-late-as-possible (ALAP) schedules, and the corresponding mobility of operators are generated. From this, operator coloring technique is used on conflict and nonconflict directed graphs using recursive functions and explicit stack mechanisms. For each feasible number of pipeline stages, a pipeline schedule with minimum total register width is taken as an optimal coloring, which is then automatically transformed to a description in CAL. The generated pipelined CAL descriptions are finally synthesized to hardware description languages for FPGA implementation. Experimental results of three video processing applications demonstrate up to 3.9× higher throughput for pipelined compared to non-pipelined implementations, and average total pipeline register width reduction of up to 39.6 and 49.9% between the optimal, and ASAP and ALAP pipeline schedules, respectively.\",\n \"Title: Smart camera based on embedded HW/SW coprocessor\\nYear: 2008\\n\\nAbstract: This paper describes an image acquisition and a processing system based on a new coprocessor architecture designed for CMOS sensor imaging. The system exploits the full potential CMOS selective access imaging technology because the coprocessor unit is integrated into the image acquisition loop. The acquisition and coprocessing architecture are compatible with the majority of CMOS sensors. It enables the dynamic selection of a wide variety of acquisition modes as well as the reconfiguration and implementation of high-performance image preprocessing algorithms (calibration, filtering, denoising, binarization, pattern recognition). Furthermore, the processing and data transfer, from the CMOS sensor to the processor, can be operated simultaneously to increase achievable performances. The coprocessor architecture has been designed so as to obtain a unit that can be configured on the fly, in terms of type and number of chained processing stages (up to 8 successive predefined preprocessing stages), during the image acquisition process that can be defined by the user according to each specific application requirement. Examples of acquisition and processing performances are reported and compared to classical image acquisition systems based on standard modular PC platforms. The experimental results show a considerable increase of the achievable performances.\",\n \"Title: An efficient motion estimation algorithm based on tracing techniques on large search windows\\nYear: 1998\\n\\nAbstract: Motion estimation represents the most computationally intensive task for all efficient motion compensated compression standards. This fact, despite the several efforts aiming at reducing its complexity, still constitutes a serious obstacle for obtaining the highest quality results theoretically achievable by the standard. This is particularly evident when critical conditions occur, such as when very large search windows are needed to have efficient motion prediction for sequences containing large displacements. In this paper we present a new block motion estimation technique, based on the combination of the tracing of trajectories obtained from the already coded motion field and a genetic heuristic search. This technique can be applied to any group of picture structure of any block based compression standard, with a complexity reduction factor up to more than two orders of magnitude at optimal coding results\",\n \"Title: A Platform for the Development and the Validation of HW IP Components Starting from Reference Software Specifications\\nYear: 2008\\n\\nAbstract: Signal processing algorithms become more and more performing and efficient as result of new developments or at the release of new standards. This fact is particularly true in the field of multimedia and video compression. However, at each improvement in efficiency and functionality the complexity of the algorithms is also increasing. Textual specifications, that in the past were the original form of specifications, have been sub- stituted by reference software packages which have become the starting point of any design flow leading to the implementation of the algorithm. Therefore designing an embedded application has become equivalent to port a generic SW on a, possibly heterogeneous, embedded platform. Such operation is getting more and more difficult and resource consuming for the increased algorithm complexity and for the wide range of architectural solutions provided by a plethora of heterogeneous SW/HW embedded platforms. This paper describes a new platform aiming at supporting a step-by-step mapping of a reference software (i.e. generic and non optimized sequential software specification) into a SW and HW implementation. The platform provides a seamless interface between the software and hardware environments and in addition is supported by profiling capabilities able to analyze the transfers of data between HW and SW parts of the algorithm. Such profiling capabilities can help the designer to achieve different implementations aiming at specific objectives such as the optimization of hardware processing resources, of the memory architectures, or the minimization of data transfers to reach low power designs.\",\n \"Title: Reconfigurable media coding: An overview\\nYear: 2013\\n\\nAbstract: This paper provides an overview of the rationale of the Reconfigurable Media Coding framework developed by MPEG standardization committee to overcome the limits of traditional ways of providing decoder specifications. Such framework is an extension of the Reconfigurable Video coding framework now encompassing also 3D Graphics coding standard. The idea of this approach is to specify decoders using an actor dataflow based representation consisting of self-contained processing units (coding tools) connected altogether and communicating by explicitly exchanging data. Such representation provides a specification for which several properties of the algorithms interesting for codec implementations are explicitly exposed and can be used for exploring different implementation objectives.\",\n \"Title: Reconfigurable video coding on multicore\\nYear: 2009\\n\\nAbstract: This article provides an overview of the main objectives of the new RVC standard, with an emphasis on the features that enable efficient implementation on platforms with multiple cores. A brief introduction to the methodologies that efficiently map RVC codec specifications to multicore platforms is accompanied with an example of the possible breakthroughs that are expected to occur in the design a...\",\n \"Title: Building multimedia security applications in the MPEG reconfigurable video coding (RVC) framework\\nYear: 2011\\n\\nAbstract: Although used by most of system developers, imperative languages are known for not being able to provide easily reconfigurable, platform independent and strictly modular applications. ISO/IEC has recently developed a new video coding standard called Reconfigurable Video Coding (RVC), with the objective of providing modular and concurrent specifications of complex video codecs that constitute a better starting point for implementation of applications using video compression. Multimedia security applications are traditionally developed in imperative languages mainly because the required multimedia codecs were only available in specification and implementations based on imperative languages. Therefore, aside from the technical challenges inherited from multimedia codecs, multimedia security applications also face a number of other challenges which are only specific to them. Since a number of multimedia codecs are already available in the RVC framework, multimedia security applications can now also be developed using this new development framework. This paper explains why the RVC framework approach can be used to efficiently overcome those technical challenges better than existing imperative languages. In addition, the paper demonstrates how the RVC framework can be used to quickly develop multimedia security applications by presenting some examples including a joint H.264/AVC video encryption-encoding system, a joint JPEG image encryption-encoding system and a image watermarking system in JPEG compressed-domain.\",\n \"Title: Special Issue: Algorithm/Architecture Co-Exploration of Visual Computing on Emerging Platforms\\nYear: 2009\\n\\nAbstract: Provides notice of upcoming special issue(s) of interest to practitioners and researchers.\",\n \"Title: Reconfigurable Media Coding: Self-Describing Multimedia Bitstreams\\nYear: 2007\\n\\nAbstract: The development of MP3 and JPEG sparked an explosion in digital content on the internet. These early encoding formats have since been joined by many others, including Quicktime, Ogg, MPEG-2 and MPEG-4, which poses an escalating challenge to vendors wishing to develop devices that interoperate with as much content as possible. This paper presents aspects of Reconfigurable Media Coding (RMC), a project currently underway at MPEG to define a self-describing bitstream format. In other words, an RMC bitstream contains metadata to assemble a decoder from a fundamental building-blocks, as well as a schema that describes the syntax of the content data, and how it may be parsed. RMC makes it easy to extend (reconfigure) existing codecs, for example adding error resilience or new chroma-subsampling profiles, or to build entirely new codecs. This paper addresses the bitstream syntax component of RMC, validating the approach by applying it to the recent MPEG-4 Video simple profile coder.\",\n \"Title: A hybrid decoder configuration of MPEG-4 and AVS in reconfigurable video coding framework\\nYear: 2009\\n\\nAbstract: This demonstration shows that the RVC framework offers a great flexibility in selecting coding tools for decoder reconfigurations to satisfy a wide variety of different applications by showing a hybrid decoder reconfiguration using coding tools from MPEG and AVS Video Tool Library (VTL). Compared with the original MPEG-4 simple profile (SP), complexity of the reconfigured decoder is reduced whereas the performance is improved gradually as the bitrate increases.\",\n \"Title: Video decoder reconfigurations and AVS extensions in the new MPEG reconfigurable video coding framework\\nYear: 2008\\n\\nAbstract: Multimedia devices are now required to support multiple coding standards. Supporting seamlessly both interoperability between standards and flexibility for application specific optimizations is a great challenge for current video coding technology. After a brief description of the new MPEG reconfigurable video coding (RVC) framework, this paper describes possible decoder reconfigurations within this framework. The essential idea behind this framework is to reuse as most as possible the algorithms or architectures which are common to several different standards and to reconfigure video decoders in a flexible way at the coding tool level. A coding tool is an encapsulated piece of algorithm. Reconfiguration can address specific optimization objectives such as improvement in colour reproduction or higher performance at high bitrate. These simple examples show that the tool level definition of the video tool library is flexible enough to support the incremental introduction of new coding algorithms, the usage of algorithms taken from different video standards (i.e. AVS is provided in one example), and the possibility of high level reconfigurations. Thus, this paper demonstrates that the RVC framework offers a great flexibility in selecting coding tools for decoder reconfigurations to satisfy a wide variety of different applications.\",\n \"Title: An Integrated Environment For Hw/Sw Co-Design Based On A Cal Specification And Hw/Sw Code Generators\\nYear: 2009\\n\\nAbstract: This demonstration presents an integrated environment that translates a CAL-based dataflow specification [1] into a heterogeneous implementation, composed by HDL and C codes. The demonstration focuses on the capability of the co-design environment to automatically build an executable heterogeneous system implementation running on a platform composed of a processor and a FPGA from the annotation of the CAL specification. The possibility of direct synthesis from a high level specification is a crucial issue for enabling efficient re-design cycles that include rapid prototyping and validation of performances of the final implementation. The design approach enabled by such integrated environment is particularly suited for development of complex processing systems such as video codecs. As a case study, the demonstration provides the analysis and validation of different software and hardware partitioning of a MPEG-4 Simple Profile decoder.\",\n \"Title: Real-Time Constraints and Prediction of Video Decoding Time for Multimedia Systems\\nYear: 1998\\n\\nAbstract: The implementation of software based video/audio decoders is an advantageous solution over traditional dedicated hardware systems. However, simultaneously guaranteeing real-time performance, needed for processing video/audio bit-streams, and an efficient use of the processing power, remains a very difficult task. In this paper, we briefly discuss the main reasons of such difficulties and we present a new technique able to predict the decoding time of compressed video bit-streams without the need of the actual decoding. This result can be obtained when appropriate statistics about the actual decoding process are included and transmitted with the compressed video data. We also show how such results can be used to implement new efficient processing resource allocation strategies. New possible schemes of intelligent interactions, and in particular an efficient implementation of Computational Graceful Degradation, between the encoder and the real-time OS are also proposed. An example of results obtained implementing the proposed technique for the MPEG-4 VM6 video algorithm is presented. Although the techniques and concepts presented in this paper are of general application, they can only be used for video compression standards capable of transmitting in any appropriate form the associated statistical coding information. This capability has been included in the new defined MPEG-4 standard.\",\n \"Title: Performance Benchmarking Of Rvc Based Multimedia Specifications\\nYear: 2013\\n\\nAbstract: The Reconfigurable Video Coding (RVC) framework was developed to specify video codecs as abstract and as much as possible implementation-agnostic descriptions, which are supposed to be processed by code synthesis tools to automatically generate implementations for different target languages and platforms. However, there are still questions about if the run-time performance of these automatically generated RVC-based codec implementations is good enough to run efficiently on different target platforms. In this paper, we present a performance benchmarking study on various RVC-based multimedia specifications (H.264/AVC and JPEG codecs, and four multimedia security systems based on these codecs), which covers the following two aspects: 1) the run-time performance against their corresponding non-RVC implementations on a single-core machine; 2) the performance gain these RVC-based implementations on a dual-core machine. Based on our benchmarking results, which show that RVC-based multimedia implementations achieve adequate/acceptable performance, we conclude that RVC has the potential to become a general-purpose but still performance-efficient development framework for many application domains.\",\n \"Title: The MIN PFS problem and piecewise linear model estimation\\nYear: 2002\\n\\nAbstract: We consider a new combinatorial optimization problem related to linear systems (MIN PFS) that consists, given an infeasible system, in finding a partition into a minimum number of feasible subsystems. MIN PFS allows formalization of the fundamental problem of piecewise linear model estimation, which is an attractive alternative when modeling a wide range of nonlinear phenomena. Since MIN PFS turns out to be NP-hard to approximate within every factor strictly smaller than 3/2 and we are mainly interested in real-time applications, we propose a greedy strategy based on randomized and thermal variants of the classical Agmon-Motzkin-Schoenberg relaxation method for solving systems of linear inequalities. Our method provides good approximate solutions in a short amount of time. The potential of our approach and the performance of our algorithm are demonstrated on two challenging problems from image and signal processing. The first one is that of detecting line segments in digital images and the second one that of modeling time-series using piecewise linear autoregressive models. In both cases the MIN PFS-based approach presents various advantages with respect to conventional alternatives, including wider range of applicability, lower computational requirements and no need for a priori assumptions regarding the underlying structure of the data.\",\n \"Title: A computationally efficient method for polyphonic pitch estimation\\nYear: 2009\\n\\nAbstract: This paper presents a computationally efficient method for polyphonic pitch estimation. The method employs the Fast Resonator Time-Frequency Image (RTFI) as the basic time-frequency analysis tool. The approach is composed of two main stages. First, a preliminary pitch estimation is obtained by means of a simple peak-picking procedure in the pitch energy spectrum. Such spectrum is calculated from the original RTFI energy spectrum according to harmonic grouping principles. Then the incorrect estimations are removed according to spectral irregularity and knowledge of the harmonic structures of the music notes played on commonly used music instruments. The new approach is compared with a variety of other frame-based polyphonic pitch estimation methods, and results demonstrate the high performance and computational efficiency of the approach.\",\n \"Title: CAL Dataflow Components for an MPEG RVC AVC Baseline Encoder\\nYear: 2011\\n\\nAbstract: In this paper, an efficient H.264/AVC baseline encoder, described in RVC-CAL actor language, is introduced. The main aim of the paper is twofold: a) to demonstrate the flexibility and ease that is provided by RVC-CAL, which allows for efficient implementation of the presented encoder, and b) to shed light on the advantages that can be brought into the RVC framework by including such encoding tools. The main modules of the designed encoder include: Inter Frame Prediction (Motion Estimation/Compensation), Intra Frame Prediction, and Entropy Coding. Descriptions of the designed modules, accompanied with RVC-CAL design issues are provided. A comparison between different development approaches is also provided. The obtained results show that specifying complex video codecs (e.g. H.264/AVC encoder) using RVC-CAL followed by automatic translation into HDL, which is achievable by the tools that support the standard, results in more efficient HW implementation compared to the traditional HW design flow. A discussion that explains the reasons behind such results concludes the paper.\",\n \"Title: Techniques for Optimization of Net Algorithms\\nYear: 2002\\n\\nAbstract: In this paper, techniques for optimization of net algorithms describing parallel asynchronous computations and derived from cycling and branching behavioral descriptions are presented. The parallelization level of the algorithms is defined by a set of parallel operator pairs. The optimization techniques cover the two key steps of parallelization flow: the generation of an optimal initial set of parallel operator pairs to meet the constraints on the execution time or implementation cost, and the generation of the final set of pairs to solve the net algorithm existence problem. The quality of the proposed techniques is evaluated by experimental results. The techniques based on the minimization of the net algorithm critical paths estimated using the maximal weight cliques of the sequential and parallel operator graphs constitute the most efficient approach to the generation of the initial and final sets of parallel operator pairs.\",\n \"Title: High-level dataflow design of signal processing systems for reconfigurable and multicore heterogeneous platforms\\nYear: 2014\\n\\nAbstract: The potential computational power of today multicore processors has drastically improved compared to the single processor architecture. Since the trend of increasing the processor frequency is almost over, the competition for increased performance has moved on the number of cores. Consequently, the fundamental feature of system designs and their associated design flows and tools need to change, so that, to support the scalable parallelism and the design portability. The same feature can be exploited to design reconfigurable hardware, such as FPGAs, which leads to rethink the mapping of sequential algorithms to HDL. The sequential programming paradigm, widely used for programming single processor systems, does not naturally provide explicit or implicit forms of scalable parallelism. Conversely, dataflow programming is an approach that naturally provides parallelism and the potential to unify SW and HDL designs on heterogeneous platforms. This study describes a dataflow-based design methodology aiming at a unified co-design and co-synthesis of heterogeneous systems. Experimental results on the implementation of a JPEG codec and a MPEG 4 SP decoder on heterogeneous platforms demonstrate the flexibility and capabilities of this design approach.\",\n \"Title: Representing Guard Dependencies in Dataflow Execution Traces\\nYear: 2013\\n\\nAbstract: Heterogeneous parallel systems are becoming mainstream computing platforms nowadays. One of the main challenges the development community is currently facing is how to fully exploit the available computational power when porting existing programs or developing new ones with available techniques. In this direction, several design space exploration methods have been presented and extensively adopted. However, defining the feasible design space of a dynamic dataflow program still remains an open issue. This paper proposes a novel methodology for defining such a space through a serial execution. Homotopy theoretic methods are used to demonstrate how the design space of a program can be reconstructed from its serial execution trajectory. Moreover, the concept of dependencies graph of a dataflow program defined in the literature is extended with the definition of two new kinds of dependencies - the Guard Enable and Disable - and the 3-tuple notion needed to represent them.\",\n \"Title: Overview of the MPEG Reconfigurable Video Coding Framework\\nYear: 2011\\n\\nAbstract: Video coding technology in the last 20 years has evolved producing a variety of different and complex algorithms and coding standards. So far the specification of such standards, and of the algorithms that build them, has been done case by case providing monolithic textual and reference software specifications in different forms and programming languages. However, very little attention has been given to provide a specification formalism that explicitly presents common components between standards, and the incremental modifications of such monolithic standards. The MPEG Reconfigurable Video Coding (RVC) framework is a new ISO standard currently under its final stage of standardization, aiming at providing video codec specifications at the level of library components instead of monolithic algorithms. The new concept is to be able to specify a decoder of an existing standard or a completely new configuration that may better satisfy application-specific constraints by selecting standard components from a library of standard coding algorithms. The possibility of dynamic configuration and reconfiguration of codecs also requires new methodologies and new tools for describing the new bitstream syntaxes and the parsers of such new codecs. The RVC framework is based on the usage of a new actor/ dataflow oriented language called CAL for the specification of the standard library and instantiation of the RVC decoder model. This language has been specifically designed for modeling complex signal processing systems. CAL dataflow models expose the intrinsic concurrency of the algorithms by employing the notions of actor programming and dataflow. The paper gives an overview of the concepts and technologies building the standard RVC framework and the non standard tools supporting the RVC model from the instantiation and simulation of the CAL model to software and/or hardware code synthesis.\",\n \"Title: OpenDF: a dataflow toolset for reconfigurable hardware and multicore systems\\nYear: 2008\\n\\nAbstract: This paper presents the OpenDF framework and recalls that dataflow programming was once invented to address the problem of parallel computing. We discuss the problems with an imperative style, von Neumann programs, and present what we believe are the advantages of using a dataflow programming model. The CAL actor language is briefly presented and its role in the ISO/MPEG standard is discussed. The Dataflow Interchange Format (DIF) and related tools can be used for analysis of actors and networks, demonstrating the advantages of a dataflow approach. Finally, an overview of a case study implementing an MPEG- 4 decoder is given.\",\n \"Title: Fast Line Detection Algorithms Based on Combinatorial Optimization\\nYear: 2001\\n\\nAbstract: In this paper we present a new class of algorithms for detecting lines in digital images. The approach is based on a general formulation of a combinatorial optimization problem. It aims at estimating piecewise linear models. A linear system is constructed with the coordinates of all contour points in the image as coefficients and the line parameters as unknowns. The resulting linear system is then partitioned into a close-to-minimum number of consistent subsystems using a greedy strategy based on a thermal variant of the perceptron algorithm. While the partition into consistent subsystems yields the classification of the corresponding image points into a close-to-minimum number of lines. A comparison with the standard Hough Transform and the Randomized Hough Transform shows the considerable advantages of our combinatorial optimization approach in terms of memory requirements, time complexity, robustness with respect to noise, possibility of introducing \\\"a priori\\\" knowledge, and quality of the solutions regardless of the algorithm parameter settings.\",\n \"Title: Quasi-Static Scheduling of CAL Actor Networks for Reconfigurable Video Coding\\nYear: 2011\\n\\nAbstract: The upcoming Reconfigurable Video Coding (RVC) standard from MPEG (ISO / IEC SC29WG11) defines a library of coding tools to specify existing or new compressed video formats and decoders. The coding tool library has been written in a dataflow/actor-oriented language named CAL. Each coding tool (actor) can be represented with an extended finite state machine and the data communication between the tools are described as dataflow graphs. This paper proposes an approach to model the CAL actor network with Parameterized Synchronous Data Flow and to derive a quasi-static multiprocessor execution schedule for the system. In addition to proposing a scheduling approach for RVC, an extension to the well-known permutation flow shop scheduling problem that enables rapid run-time scheduling of RVC tasks, is introduced.\",\n \"Title: A Software/Hardware Platform for Rapid Prototyping of Video and Multimedia Designs\\nYear: 2005\\n\\nAbstract: Traditional design and test of complex multimedia systems involves a large number of test vectors and is a difficult and time-consuming task. The simulation times are prohibitively long on current desktop computers. Driving actual design scenarios and timing burst behavior which produce real-time effects is difficult to do with current simulation environments. This paper describes a rapid emulation framework for accessing multiple hardware IP blocks on an FPGA. This solution involves an abstraction of the FPGA platform by having a virtual socket layer that resides between the design and the test vehicles. A rapid prototyping platform is thus created, and its use with complex video and multimedia systems is described.\",\n \"Title: The Reconfigurable Video Coding Standard [Standards in a Nutshell]\\nYear: 2010\\n\\nAbstract: More than two decades of research in digital video technologies, together with the emergence of successful international standards for digital video compression, have led to a wide variety of digital video products using video compression for professional and consumer applications. Although many of these video compression standards share common and/or similar coding tools, there is currently no explicit way to exploit such commonalities at the level of the specifications nor at the level of implementations. Moreover, the possibility of taking advantage of the benefits of the continuous improvements of coding technology is only possible by replacing an old standard with a new one. This usually results in the replacement of the existing multimedia devices with new ones capable of handling the new deployed standards. Such necessity is not always well accept-ed by the public and professionals for obvious reasons.\",\n \"Title: A new time-frequency representation for music signal analysis: Resonator time-frequency image\\nYear: 2007\\n\\nAbstract: Most of music related tasks need a joint time-frequency analysis because a music signal varies with time. The existing time-frequency analysis approaches show some serious limitations for application in music signal processing. This paper presents an original frequency-dependent time-frequency analysis tool called the Resonator Time-Frequency Image (RTFI). The RTFI is implemented by a first-order complex resonator bank so as to be computation-efficient. Different music analysis tasks may have different time-frequency resolution requirements. Using the RTFI, one can select different time-frequency resolutions, such as uniform analysis, constant-Q analysis, or ear-like analysis by simply setting different parameters; and letting the RTFI generalize all these analyses in one framework. An example of using the RTFI in music onset detection is introduced.\",\n \"Title: A Perceptron-Based Approach to Piecewise Linear Modeling with an Application to Time Series\\nYear: 1997\\n\\nAbstract: . Piecewise linear models are attractive when modeling a widerange of nonlinear phenomena but determining simultaneously the datapartition and the parameter values of the corresponding submodels is achallenging problem. We show that this problem can be formulated asthat of partitioning an inconsistent linear system into a minimum numberof consistent subsystems and we describe a greedy algorithm, basedon a simple variant of the perceptron procedure, which provides goodapproximate...\",\n \"Title: SMIL to MPEG-4 BIFS Conversion\\nYear: 2006\\n\\nAbstract: The current trend in the evolution of the Web is towards an every increasing demand for personalized Web contents. Tailoring Web resources to the characteristics of heterogeneous client devices and user preferences opens two main novel issues in the ...\",\n \"Title: Actor Merging for Dataflow Process Networks\\nYear: 2015\\n\\nAbstract: Dataflow process networks provide a versatile model of computation for specifying signal processing applications in a platform independent fashion. This attractive feature of dataflow has lately been realized in dataflow programming tools that allow synthesizing the same application specification as both fixed hardware circuits and as software for programmable processors. However, in practice, the specification granularity of the dataflow program remains an arbitrary choice of the designer. Dataflow specifications of the same application with equivalent I/O behaviour can range from a single dataflow actor to a very fine grained network composed of elementary processing operations. A very fine grained dataflow specification might result into a high performance implementation when synthesized as hardware, but might perform poorly when executed on a programmable processor. This article presents actor merging as one solution for this performance portability problem of dataflow programs. In contrast to previous work around actor merging, this article presents a methodology that can merge also dynamic dataflow actors. To support these claims, results of experiments on several processing platforms and application examples ranging from telecommunications to video compression are reported.\",\n \"Title: Image visual quality restoration by cancellation of the unmasked noise\\nYear: 1994\\n\\nAbstract: The aim of image restoration is to find an estimate of the ideal image using a priori information about blur and/or noise and/or the ideal image. Classical criterion are minimum least square, minimum mean square error or maximum a posteriori probability. The choice of the criterion used to measure the estimation quality is crucial for the design of the restoration algorithm. The authors propose a new criterion based on a visual model: it is based on perceptual masking. Thereafter, they propose a new restoration algorithm dealing only with additive noise. The perceptual components of the image to restore which are corrupted by an additive noise above a visibility threshold are simply set to zero. Some results obtained for the post-processing of JPEG images are presented\",\n \"Title: Exploring MPEG HEVC decoder parallelism for the efficient porting onto many-core platforms.\\nYear: 2014\\n\\nAbstract: MPEG High Efficient Video Coding (HEVC) is likely to emerge as the video coding standard for HD and Ultra-HD TV resolutions. The two elements that push HEVC beyond the previous standards are a higher compression efficiency of about a factor of two, and the introduction of new coding tools, tiles and wavefront that are intended to ease the largely increased encoding complexity particularly for Ultra HD resolutions such as 4K and 8K. However, for HEVC decoder implementations, the achievement of the desired performance on massive parallel platforms cannot rely on the use of such optional (not enforced by MPEG profiles) tools. This paper reports results about the intrinsic parallelism of compliant HEVC decoding algorithms obtained by analyzing a dataflow implementation written using the standard language specified in ISO/IEC 23001-4 and structured attempting to maximize the algorithmic potential parallelism. The experimental results show what is the parallelism achieved by different dataflow architectures and how it can be further combined with the parallelism achieved by relying on tiles and wavefront, whenever they would be available, for porting a compliant HEVC decoder on massive parallel many-core platforms.\",\n \"Title: Characterizing communication behavior of dataflow programs using trace analysis\\nYear: 2014\\n\\nAbstract: This paper investigates the relationship between two ways of analyzing streaming systems: trace analysis for dataflow programs with firing, and network calculus for network flows. While the former focuses on the structure of the dataflow computation while idealizing the interaction with the environment, the latter characterizes the temporal properties of flows of data, largely abstracting from the computations that connect them. In this work, we show how a trace analysis can be used to derive a description of communication behavior of a dataflow program in terms of network calculus, which is then applied to answering a question about the buffer sizing. The example being studied is an MPEG-4 video decoder.\",\n \"Title: A methodology for optimizing buffer sizes of dynamic dataflow fpgas implementations\\nYear: 2014\\n\\nAbstract: Minimizing buffer sizes of dynamic dataflow implementations without introducing deadlocks or reducing the design performance is in general an important and useful design objective. Indeed, buffer sizes that are too small causing a system to deadlock during execution, or dimensioning unnecessarily large sizes leading to a resource inefficient design are both not a desired design option. This paper presents an implementation, validation, and comparison of several buffer size optimization techniques for the generic class of dynamic dataflow model of computation called the dataflow process network. The paper presents an heuristic capable of finding a close-to-minimum buffer size configuration for deadlock-free executions, and a methodology to efficiently explore different configurations for feasible design alternatives. The approach is demonstrated using as experimental design case, an MPEG-4 AVC/H.264 decoder implemented on an FPGA.\",\n \"Title: Profiling of Dataflow Programs Using Post Mortem Causation Traces\\nYear: 2012\\n\\nAbstract: The natural representation of data streams, parallelism, and composition has made dataflow an attractive programming model for expressing a wide range of stream and media processing applications, and has led MPEG and ISO to base their latest video coding standards on this model. This paper describes and compares methodologies and metrics for the optimization of signal processing algorithms represented as dataflow programs. Our approach is based on the analysis of traces and addresses some of the complexity challenges that arise from the very large data sets that are required for evaluating real-world applications. The methodology and experimental results are demonstrated and evaluated in two at-size case studies, an MPEG-4 SP and an AVC/H.264 video decoders.\",\n \"Title: A Virtual Socket Framework for Rapid Emulation of Video and Multimedia Designs\\nYear: 2005\\n\\nAbstract: Traditional design and test of complex multimedia systems involves a large number of test vectors and is a difficult and time-consuming task. The simulation times are prohibitively long on current desktop computers. Driving actual design scenarios and timing burst behavior which produce real-time effects is difficult to do with current simulation environments. This paper describes a rapid emulation framework for accessing multiple hardware IP blocks on an FPGA. This solution involves an abstraction of the FPGA platform by having a virtual socket layer that resides between the design and the test vehicles. A rapid prototyping platform is thus created, and its use with complex video and multimedia systems is described.\",\n \"Title: Configurable motion-estimation hardware accelerator module for the MPEG-4 reference hardware description platform\\nYear: 2005\\n\\nAbstract: This paper describes a motion estimation co-processor architecture that explicitly separates the implementation stages consisting of data access to the search window and the evaluation of the matching criterion from the implementation of the search strategy. The architecture is modular and can be re-configured according to the different MPEG video coding profiles and level parameters. Although the architectural solutions described here can be in principle applied to any SoC implementation technologies, the solution presented here is expressly conceived and validated on FPGA co- processing architectures supporting mixed SW/HW implementations of video encoders such as generic PC platforms with a standard PCMCIA FPGA cards. The module has been developed in the framework of the MPEG reference hardware description activity.\",\n \"Title: Optimization of portable parallel signal processing applications by design space exploration of dataflow programs\\nYear: 2011\\n\\nAbstract: This paper describes a methodology for the optimization of portable parallel signal processing applications specified by dataflow programs. The use of dataflow as a programming model for signal processing applications targeting parallel platforms provides an important advantage versus the traditional sequential programming paradigm: the portability of parallelism. The paper introduce a design space exploration methodology for exploring alternative implementations in which abstract traces of a program, representing the actual data dependencies of its parts, are first constructed and then analyzed to guide the refactoring and mapping and of the signal processing applications to best match its intended parallel target. The methodology is demonstrated and evaluated in an at-size case study of an MPEG-4 video decoder.\",\n \"Title: Scheduling of dynamic dataflow programs based on state space analysis\\nYear: 2012\\n\\nAbstract: Compile-time scheduling of dynamic dataflow programs is still an open problem. This paper presents how scheduling of dynamic portions of asynchronous dataflow networks described using CAL language can be determined before execution by the analysis of the state space of network partitions. Experiments show that the number of run-time operations employed by dynamic schedulers is largely reduced when the schedules extracted by the state analysis are employed.\",\n \"Title: High level design space exploration of RVC codec specifications for multi-core heterogeneous platforms\\nYear: 2010\\n\\nAbstract: Nowadays, the design flow of complex signal processing embedded systems starts with a specification of the application by means of a large and sequential program (usually in C/C++). As we are entering in the multicore era, sequential programs are no longer the most appropriate way to specify algorithms targeted to run on several processing units. The new ISO/MPEG Reconfigurable Video Coding (RVC) standard is proposing a new paradigm for specifying and designing complex signal processing systems. The RVC standard enables specifying new codecs by assembling blocks, or so called Functional Units (FUs) from a standard Video Tool Library (VTL). Flexibility, reusability, and modularity are the key features of RVC. This new way of specifying algorithms clearly simplifies the task of designing future video coding applications by allowing software and hardware reuse across multiple video coding standards. Specifications are provided in the form of an actor and dataflow-based language called CAL. Although the RVC standard does not imply any specific implementation design flow, it is an appropriate starting point for targeting multiple processing units platforms. This paper describes a new model-driven design flow which considers both algorithm and architecture to map RVC codec specifications onto heterogeneous and multi-core systems.\",\n \"Title: Systems design space exploration by serial dataflow program execution\\nYear: 2013\\n\\nAbstract: The increasing ubiquity of heterogeneous parallel computing platforms nowadays creates the challenge to fully exploit the available computational power when porting existing programs or developing new applications with portability in mind. Existing design space exploration methods focus on specialized applications amenable to compile-time analysis. Real-world applications, however, tend to exhibit complex behavior that depends on input data and even timing. This paper proposes a methodology for creating a finite (approximate) representation of the design space of general streaming applications, based on detailed tracking of a serial run of the program. Homotopy theoretic methods are used to demonstrate how the design space of a program can be reconstructed from its serial execution trajectory. Moreover, the concept of a dependency graph of a dataflow program defined in the literature is extended with the definition of two new kinds of dependencies - the Guard Enable and Disable - and the 3-tuple notion needed to represent them.\",\n \"Title: Buffer optimization based on critical path analysis of a dataflow program design\\nYear: 2013\\n\\nAbstract: The trade-off between throughput and memory constraints is a common design problem in embedded systems, and especially for streaming applications, where the memory in question usually occurs in the form of buffers for streams of data. This paper presents a methodology, based on the post-processing of dataflow execution traces, that enables designers to make principled choices in the design space for arbitrary streaming applications in a scalable manner. It significantly extends the class of applications over traditional compile-time-only techniques, and effectively enables designers to find a close-to-minimum solution for this NP-complete problem. A heuristic algorithm exploring different buffer size configurations lets designers choose appropriate alternatives and enables them to rapidly navigate the design space. Methodology and experimental results are demonstrated in an at-size scenario using a real-world MPEG-4 SP decoder.\",\n \"Title: Dataflow program analysis and refactoring techniques for design space exploration: MPEG-4 AVC/H.264 decoder implementation case study\\nYear: 2013\\n\\nAbstract: This paper presents a methodology to perform design space exploration of complex signal processing systems implemented using the CAL dataflow language. In the course of space exploration, critical path in dataflow programs is first presented, and then analyzed using a new strategy for computational load reduction. These techniques, together with detecting design bottlenecks, point to the most efficient optimization directions in a complex network. Following these analysis, several new refactoring techniques are introduced and applied on the dataflow program in order to obtain feasible design points in the exploration space. For a MPEG-4 AVC/H.264 decoder software and hardware implementation, the multi-dimensional space can be explored effectively for throughput, resource, and frequency, with real-time decoding range from QCIF to HD resolutions.\",\n \"Title: Modeling control tokens for composition of CAL actors\\nYear: 2013\\n\\nAbstract: Dataflow programming is typically used as an intuitive representation for describing multimedia and signal processing applications as computation nodes which communicate through FIFO queues. To run a dataflow network, consisting of several nodes, either run-time or compile-time scheduling is required. Compile-time scheduling techniques are typically based on token rates between nodes and for languages such as CAL, which are expressive enough to describe an actor with any behavior, run-time scheduling is needed in the general case, introducing an overhead. However, the well defined structure of dataflow programs enables analysis of the dependencies of the program and partitions with piecewise static schedules can be derived. In this paper we describe how actor partitions with control tokens can be modeled such that a correct scheduler, where most scheduling decisions are taken at compile-time, can be derived for the resulting composed actor.\",\n \"Title: Turnus: A unified dataflow design space exploration framework for heterogeneous parallel systems\\nYear: 2013\\n\\nAbstract: This paper presents the main features of the TURNUS co-exploration environment, an unified design space exploration framework suitable for heterogeneous parallel systems designed using an high level dataflow representation. The main functions of this tool are illustrated through the analysis of a video decoder implemented in the RVC-CAL dataflow language.\",\n \"Title: A Methodology For Profiling And Partitioning Stream Programs On Many-Core Architectures\\nYear: 2015\\n\\nAbstract: Maximizing the data throughput is a very common implementation objective for several streaming applications. Such task is particularly challenging for implementations based on many-core and multi-core target platforms because, in general, it implies tackling several NP-complete combinatorial problems. Moreover, an efficient design space exploration requires an accurate evaluation on the basis of dataflow program execution profiling. The focus of the paper is on the methodology challenges for obtaining accurate profiling measures. Experimental results validate a many-core platform built by an array of Transport Triggered Architecture processors for exploring the partitioning search space based on the execution trace analysis.\",\n \"Title: Execution Trace Graph Based Multi-Criteria Partitioning Of Stream Programs\\nYear: 2015\\n\\nAbstract: One of the problems proven to be NP-hard in the field of many-core architectures is the partitioning of stream programs. In order to maximize the execution parallelism and obtain the maximal data throughput for a streaming application it is essential to find an appropriate actors assignment. The paper proposes a novel approach for finding a close-to-optimal partitioning configuration which is based on the execution trace graph of a dataflow network and its analysis. We present some aspects of dataflow programming that make the partitioning problem different in this paradigm and build the heuristic methodology on them. Our optimization criteria include: balancing the total processing workload with regards to data dependencies, actors idle time minimization and reduction of data exchanges between processing units. Finally, we validate our approach with experimental results for a video decoder design case and compare them with some state-of-the-art solutions.\",\n \"Title: Execution trace graph analysis of dataflow programs: Bounded buffer scheduling and deadlock recovery using model predictive control\\nYear: 2014\\n\\nAbstract: Execution trace graph analysis of dataflow programs has been demonstrated to be an effective way for exploring and optimizing the design space of many core applications. In this work a novel transformation from the execution trace graph to an event driven linear system is proposed. It is also illustrated how the trace space of can be effectively reduced and well known system control techniques can be efficiently used in order to find close to optimal solutions. In particular, the problem of finding a bounded buffer size configuration is proposed and solved using a model predictive controller. Two design examples, a JPEG and an MPEG HEVC decoder have been used to demonstrate the effectiveness of the approach.\",\n \"Title: TURNUS: An open-source design space exploration framework for dynamic stream programs\\nYear: 2014\\n\\nAbstract: Although the research on the design of heterogeneous concurrent systems has a long and rich history, a unified design methodology and tool support have not emerged so far. Therefore, the creation of such systems remains a difficult, time-consuming and error-prone process. The absence of principled support for system evaluation and optimization at high level of abstraction makes the quality of the resulting implementation strongly dependent on the experience or individual preferences of the designer. In this work we are presenting TURNUS, a unified dataflow design space exploration framework for heterogeneous parallel systems. This open source framework represents a decade of research on high-level modelling and simulation methods and tools for system level performance estimation and optimization. Last year we presented heuristic algorithms that were focused on the results of exploration in terms of algorithmic optimization, rapid performance estimation, application throughput, buffer size dimensioning and power optimization. This year we are presenting the novelties that have been introduced in TURNUS such as clock gating, pipelining optimization, kernel splitting algorithms, advanced partitioning algorithms and scheduling optimization based on model predictive control techniques.\",\n \"Title: Tabu Search for Partitioning Dynamic Dataflow Programs.\\nYear: 2016\\n\\nAbstract: An important challenge of dataflow programming is the problem of partitioning dataflow components onto a target architecture. A common objective function associated to this problem is to find the maximum data processing throughput. This NP-complete problem is very difficult to solve with high quality close-to-optimal solutions for the very large size of the design space and the possibly large variability of input data. This paper introduces four variants of the tabu search metaheuristic expressly developed for partitioning components of a dataflow program. The approach relies on the use of a simulation tool, capable of estimating the performance for any partitioning configuration exploiting a model of the target architecture and the profiling results. The partitioning solutions generated with tabu search are validated for consistency and high accuracy with experimental platform executions.\",\n \"Title: A Partition Scheduler Model for Dynamic Dataflow Programs.\\nYear: 2016\\n\\nAbstract: The definition of an efficient scheduling policy is an important, difficult and open design problem for the implementation of applications based on dynamic dataflow programs for which optimal closed-form solutions do not exist. This paper describes an approach based on the study of the execution of a dynamic dataflow program on a target architecture with different scheduling policies. The method is based on a representation of the execution of a dataflow program with the associated dependencies, and on the cost of using scheduling policy, expressed as a number of conditions that need to be verified to have a successful execution within each partition. The relation between the potential gain of the overall execution satisfying intrinsic data dependencies and the runtime cost of finding an admissible schedule is a key issue to find close-to-optimal solutions for the scheduling problem of dynamic dataflow applications.\",\n \"Title: Performance Estimation Based Multicriteria Partitioning Approach for Dynamic Dataflow Programs\\nYear: 2016\\n\\nAbstract: AbstractThe problem of partitioning a dataflow program onto a target architecture is a difficult challenge for any application design. In general, since the problem is NP-complete, it consists of looking for high quality solutions in terms of maximizing the achievable data throughput. The difficulty is given by the exploration of the design space which results in being extremely large for parallel platforms. The paper describes a heuristic partitioning methodology applicable to dynamic dataflow programs. The methodology is based on two elements: an execution model of the dynamic dataflow program which is used as estimation of the performance for the exploration of the large design space and several partitioning algorithms competing to lead to specific high quality solutions. Experimental results are validated with executions on a virtual platform.\",\n \"Title: An Evaluation Framework for Lossy Compression of Genome Sequencing Quality Values\\nYear: 2016\\n\\nAbstract: This paper provides the specification and an initial validation of an evaluation framework for the comparison of lossy compressors of genome sequencing quality values. The goal is to define reference data, test sets, tools and metrics that shall be used to evaluate the impact of lossy compression of quality values on human genome variant calling. The functionality of the framework is validated referring to two state-of-the-art genomic compressors. This work has been spurred by the current activity within the ISO/IEC SC29/WG11 technical committee (a.k.a. MPEG), which is investigating the possibility of starting a standardization activity for genomic information representation.\",\n \"Title: Performance estimation of program partitions on multi-core platforms\\nYear: 2016\\n\\nAbstract: The exploration of different design configurations of dynamic dataflow programs executed on many-core or multi-core platforms is, in general, a very difficult task. Determining a close-to-optimal partitioning, scheduling and buffer dimensioning configuration, when associated with a performance optimization function, belongs to the class of NP-complete problems. In order to explore the space of feasible solutions with efficient heuristics looking for solutions of good quality, it is important to be able to evaluate the design points in terms of the performance optimization function with sufficient precision without having to physically execute the program on the platform. This paper presents a performance estimation approach and an associated SW tool capable of exploring, with a high level of accuracy, the space of feasible solutions by using only a limited set of measurements from the physical processing platform. Moreover, the estimation model allows an identification of possible improvements that can be applied to different configurations. The results reported validate the accuracy of the methodology using examples of dataflow implementations of dynamic video codec designs for two different classes of platforms: Transport Triggered Architecture and Intel platforms.\",\n \"Title: High-level synthesis of dynamic dataflow programs on heterogeneous MPSoC platforms\\nYear: 2016\\n\\nAbstract: The growing complexity of digital signal processing applications make a compelling case the use of high-level design and synthesis methodologies for the implementation on programmable logic devices and embedded processors. Past research has shown that, for complex systems, raising the level of abstraction of design stages does not necessarily come at a penalty in terms of performance or resource requirements. Dataflow programs provide behavioral descriptions capable of expressing both sequential and parallel components of application algorithms and enable natural design abstractions, modularity, and portability. In this paper, an open source tool, implementing dataflow programs onto embedded heterogeneous platforms by means of high-level synthesis, software synthesis and interface synthesis is presented Experimental design results demonstrate the capability and the effectiveness of the tool for implementing a wide range of applications when combined with Vivado HLS.\",\n \"Title: High-Precision Performance Estimation of Dynamic Dataflow Programs\\nYear: 2016\\n\\nAbstract: An important challenge for a dataflow designer is to efficiently explore the design space in order to find a set of configurations that satisfy the defined objective function. The exploration directions may involve the partitioning, scheduling and buffer dimensioning, and all together should drive the designer to maximally benefit from the potential parallelism of an application. Successful exploration can be strongly facilitated by means of performance estimation. This paper presents a tool that allows a high-precision estimation of a program execution on a given platform, when various sets of configurations can be applied. It demonstrates which information related to the multi-core program execution can be extracted and successfully used to drive the optimization procedures. The experimental results are confirmed by an actual execution on different types of platforms.\",\n \"Title: Clock-Gating of Streaming Applications for Energy Efficient Implementations on FPGAs.\\nYear: 2017\\n\\nAbstract: This paper investigates the reduction of dynamic power for streaming applications yielded by asynchronous dataflow designs by using clock gating techniques. Streaming applications constitute a very broad class of computing algorithms in areas such as signal processing, digital media coding, cryptography, video analytics, network routing, packet processing, etc. This paper introduces a set of techniques that, considering the dynamic streaming behavior of algorithms, can achieve power savings by selectively switching off parts of the circuits when they are temporarily inactive. The techniques being independent from the semantic of the application can be applied to any application and can be integrated into the synthesis stage of a high-level dataflow design flow. Experimental results of at-size applications synthesized on field-programmable gate arrays platforms demonstrate power reductions achievable with no loss in data throughput.\",\n \"Title: On the Development and Optimization of HEVC Video Decoders Using High-Level Dataflow Modeling.\\nYear: 2017\\n\\nAbstract: With the emergence of the High Efficiency Video Coding (HEVC) standard, a dataflow description of the decoder part was developed as part of the MPEG-B standard. This dataflow description presented modest framerate results which led us to propose methodologies to improve the performance. In this paper, we introduce architectural improvements by exposing more parallelism using YUV and frame-based parallel decoding. We also present platform optimizations based on the use of SIMD functions and cache efficient FIFOs. Results show an average acceleration factor of 5.8 in the decoding framerate over the reference architecture.\",\n \"Title: Differential Gene Expression with Lossy Compression of Quality Scores in RNA-Seq Data\\nYear: 2017\\n\\nAbstract: High-throughput sequencing of RNA molecules has enabled the quantitative analysis of the expression of genes at the expense of storage space and processing power. To help alleviate these problems, lossy compression methods of the quality scores associated to RNA sequence data have recently been proposed, and the evaluation of their impact on downstream analysis is gaining attention. This work presents a first assessment of the impact of lossly compressed quality scores in RNA sequence data on the performance of some of the most recent tools used for differential gene expression.\",\n \"Title: High-level system synthesis and optimization of dataflow programs for MPSoCs\\nYear: 2016\\n\\nAbstract: The growing complexity of digital signal processing applications make a compelling case the use of high-level design and synthesis methodologies for the implementation on reconfigurable and embedded devices. Past research has shown that raising the level of abstraction of design stages does not necessarily gives penalties in terms of performance or resources. Dataflow programs provide behavioral descriptions capable of expressing both sequential and parallel algorithms and enable natural design abstractions, modularity, and portability. In this paper, a tool implementing dataflow programs onto embedded heterogeneous platforms by means of high-level synthesis, software synthesis and interface synthesis is presented for MPSoCs platfroms.\",\n \"Title: Trace-based manycore partitioning of stream-processing applications\\nYear: 2016\\n\\nAbstract: Application performance on these processor array platforms is highly sensitive to how functionality is physically placed on the device, as this choice crucially determines communication latencies and congestion patterns of the on-chip inter-core communication. The problem of identifying the best, or just a good enough, partitioning and placement does not, in general, admit to an analytic solution, and its combinatorial nature makes solving it by pure experimentation impractical. This paper presents an approach that maps stream programs onto processor arrays using trace analysis as a technique for evaluating candidate solutions and for suggesting alternatives.\",\n \"Title: Buffer dimensioning for throughput improvement of dynamic dataflow signal processing applications on multi-core platforms.\\nYear: 2017\\n\\nAbstract: Executing a dataflow program on a parallel platform requires assigning to each buffer a given size so that correct program executions take place without introducing any deadlock. Furthermore, in the case of dynamic dataflow programs, specific buffer size assignments lead to significant differences in the throughput, hence a more appropriate optimization problem is to specify the buffer sizes so that the throughput is maximized and the used resources are minimized. This paper introduces a new heuristic methodology for the buffer dimensioning of dynamic dataflow programs, which is considered as a stage of a more general design space exploration process.\",\n \"Title: Design Space Exploration Of Dataflow-Based Smith-Waterman Fpga Implementations\\nYear: 2017\\n\\nAbstract: The paper presents the results of design space explorations for the implementation of the Smith-Waterman (S-W) algorithm performing DNA and protein sequences alignment. Both design explorations studies and FPGA implementations are obtained by developing a dynamic dataflow program implementing the algorithm and by direct high-level synthesis (HLS) to FPGA HDL. The main feature of the obtained implementation is a low-latency, pipelinable multistage processing element (PE), providing a substantial decrease in resource utilization and increase in computation throughput when compared to state of the art solutions. The implementation solution is also fully scalable and can be efficiently reconfigured according to the DNA sequence sizes and performance requirements of the system architecture. The implementation solution presented in the paper can efficiently scale up to 250MHz obtaining 14746 Alignments/s using a single S-W core with 4 PEs, and up to 31.8 MegaAlignments/min using 36 S-W cores on the same FPGA for sequences of 160 x 100 nucleotides.\",\n \"Title: Lossy Compression of Quality Scores in Differential Gene Expression: A First Assessment and Impact Analysis\\nYear: 2018\\n\\nAbstract: High-throughput sequencing of RNA molecules has enabled the quantitative analysis of gene expression at the expense of storage space and processing power. To alleviate these problems, lossy compression methods of the quality scores associated to RNA sequencing data have recently been proposed, and the evaluation of their impact on downstream analyses is gaining attention. In this context, this work presents a first assessment of the impact of lossily compressed quality scores in RNA sequencing data on the performance of some of the most recent tools used for differential gene expression.\",\n \"Title: High-Precision Performance Estimation for the Design Space Exploration of Dynamic Dataflow Programs.\\nYear: 2018\\n\\nAbstract: The implementation and optimization of dynamic dataflow programs on multi/many-core platforms require solving a very difficult problem: how to partition and schedule the processing elements and dimension their interconnecting buffers according to given optimization functions in terms of throughput, memory usage, and energy consumption. This problem is NP-hard even for two cores. Thus, finding a cl...\",\n \"Title: Execution Trace Graph of Dataflow Process Networks.\\nYear: 2018\\n\\nAbstract: The paper introduces and specifies a formalism that provides complete representations of dataflow process network (DPN) program executions, by means of directed acyclic graphs. Such graphs, also known as execution trace graphs (ETG), are composed of nodes representing each action firing and by directed arcs representing the dataflow program execution constraints between two action firings. Action ...\",\n \"Title: Shared-variable Synchronization Approaches for Dynamic Data Flow Programs\\nYear: 2018\\n\\nAbstract: This paper presents shared-variable synchronization approaches for dataflow programming. The mechanisms do not require any substantial model of computation (MoC) modifi-cation, and is portable across both for hardware (HW) and software (SW) low-level code synthesis. With the shared-variable formalization, the benefits of the dataflow MoC are maintained, however the space and energy efficiency of an application can be significantly improved. The approach targets Dynamic Process Network (DPN) dataflow applications, thus making them also suitable for less expressive models e.g. synchronous and cyclo-static dataflow that DPN subsumes. The approach is validated through the analysis and optimization of a High-Efficiency Video Coding (HEVC) decoder implemented in the RVC-CAL dataflow language targeting a multi-core platform. Experimental results show how, starting from an initial design that does not use the shared-variable formalism, frames per second throughput performance is increased by a factor of 21.\",\n \"Title: Efficient Dynamic Optimisation Heuristics for Dataflow Pipelines\\nYear: 2018\\n\\nAbstract: Large dataflow designs appear as a result of functional specification of modern complex digital systems and/or a result of unfolding and behavioral transformation of looped and branched programs. Since deep-submicron silicon technology provides large amounts of available resources, pipelining optimization without resource sharing can give significant advantages in performance. In this work, we propose a novel pipeline optimization heuristic algorithm, which is named HADD. It is suitable for very large dataflow programs and makes use of efficient dynamic heuristics and a random search on the set of solutions. For a pipeline-stage time-period, it quickly minimizes the number of stages and successively finds the assignment of operators to stages with the objective of minimizing the overall pipeline registers size. The experimental results show that HADD gives solutions that are very close to accurate solutions with only 2% of the difference and overcomes by about 10% on average the best-known heuristic technique HT, which uses mixed static-dynamic heuristics on large designs. Moreover, HADD is c.a. 10 times faster on average against HT.\",\n \"Title: An Heterogeneous Compiler Of Dataflow Programs For Zynq Platforms\\nYear: 2019\\n\\nAbstract: In recent years, the number and variety of heterogeneous multiprocessor system-on-chip MPSoCs, such as for instance Zynq platforms, has sensibly increased. However, today all design flow solutions capable of programming the different components of such platforms require to the designer either to modify the software or hardware based designs to obtain higher performance implementations. Thus, the developer needs to either rewrite functional blocks in HDL or to use high-level synthesis of C-like sequential languages with platform locked extensions. In this paper, a compiler infrastructure that takes as input a single behavioral representation, expressed in high-level dataflow RVC-CAL language, is proposed for programming any of the components of heterogeneous Zynq MPSoCs platforms without the need of modifying any line of code on the design.\",\n \"Title: Composite Data Types In Dynamic Dataflow Languages As Copyless Memory Sharing Mechanism\\nYear: 2019\\n\\nAbstract: This paper presents new optimization approaches aiming at reducing the impact of memory accesses on the performance of dataflow programs. The approach is based on introducing a high level management of composite data types in dynamic dataflow programming language for the memory processing of data tokens. It does not require essential changes to the model of computation (MOC) or to the dataflow program itself. The objective of the approach is to remove the unnecessary constraints of memory isolations without introducing limitations to the scalability and composability properties of the dataflow paradigm. Thus the identified optimizations allow to keep the same design and programming philosophy of dataflow, whereas aiming at improving the performance of the specific configuration implementation. The different optimizations can be integrated into the current RVC-CAL design flows and synthesis tools and can be applied to different sub-networks partitions of the dataflow program. The paper introduces the context, the definition of the optimization problem and describes how it can be applied to dataflow designs. Some examples of the optimizations are provided.\",\n \"Title: An Introduction to MPEG-G: The First Open ISO/IEC Standard for the Compression and Exchange of Genomic Sequencing Data\\nYear: 2021\\n\\nAbstract: The development and progress of high-throughput sequencing technologies have transformed the sequencing of DNA from a scientific research challenge to practice. With the release of the latest generation of sequencing machines, the cost of sequencing a whole human genome has dropped to less than $\\\\$ $ 600. Such achievements open the door to personalized medicine, where it is expected that genomic information of patients will be analyzed as a standard practice. However, the associated costs, related to storing, transmitting, and processing the large volumes of data, are already comparable to the costs of sequencing. To support the design of new and interoperable solutions for the representation, compression, and management of genomic sequencing data, the Moving Picture Experts Group (MPEG) jointly with working group 5 of ISO/TC276 “Biotechnology” has started to produce the ISO/IEC 23092 series, known as MPEG-G. MPEG-G does not only offer higher levels of compression compared with the state of the art but it also provides new functionalities, such as built-in support for random access in the compressed domain, support for data protection mechanisms, flexible storage, and streaming capabilities. MPEG-G only specifies the decoding syntax of compressed bitstreams, as well as a file format and a transport format. This allows for the development of new encoding solutions with higher degrees of optimization while maintaining compatibility with any existing MPEG-G decoder.\",\n \"Title: A 0.4 nJ Excitation Energy Bridge-to-Digital Converter for Implantable Pulmonary Artery Pressure Monitoring\\nYear: 2021\\n\\nAbstract: This paper presents an energy-efficient, duty-cycled, and spinning excitation bridge-to-digital converter (BDC) suitable for measuring the pulmonary artery pressure of heart failure patients with an implantable system. The duty-cycled bridge uses resistances of 6.2 kΩ and, with a supply of 1.2 V, consumes 0.4 nJ excitation energy. A novel spinning method is applied to the bridge and the capacitive...\",\n \"Title: Performance Estimation of High-Level Dataflow Program on Heterogeneous Platforms\\nYear: 2021\\n\\nAbstract: The performance of programs written in languages following the dataflow model of computation (MoC) largely depends on the configuration (partitioning, mapping, scheduling, buffer dimensioning) chosen during the synthesis stages. Furthermore, this programming paradigm is particularly well suited for heterogeneous parallel systems because it is inherently free of memory contention and exposes parallel opportunities. Both of these statements show the necessity for a way to easily and automatically evaluate and find good design configurations. The paper describes the methodology required for clock-accurate profiling of high-level dataflow programs written in RVL-CAL when synthesized on heterogeneous CPU/GPU co-processing platforms. It also extends to the heterogeneous paradigm an existing methodology for qualitatively estimating the performance of such programs as a function of the provided configuration. This, without the need to synthesize and profile every single configuration on the actual hardware platform. This approach is validated using two application programs and several configurations.\",\n \"Title: SIMD Parallel Execution on GPU from High-Level Dataflow Synthesis\\nYear: 2021\\n\\nAbstract: Writing and optimizing application software for heterogeneous platforms including GPU units is a very difficult task that requires designer efforts and resources to consider several key elements to obtain good performance. Dataflow programming has shown to be a good approach for accomplishing such a difficult task for its properties of portability and the possibility of arbitrary partitioning a dataflow network on each unit of heterogeneous platforms. However, such a design methodology is not sufficient by itself to obtain good performance. The paper describes some methodological steps for improving the performance of dataflow programs written in RVC-CAL and synthesized to execute on heterogeneous CPU/GPU co-processing platforms. The steps do include the optimization of the performance of the communication tasks between processing elements, a strategy for the efficient scheduling of independent GPU partitions, and the introduction of dynamic programming for leveraging the SIMD nature of GPU platforms. The approach is validated qualitatively and quantitatively using dataflow application program examples executed by applying several partitioning configurations.\",\n \"Title: Methodologies for Synthesizing and Analyzing Dynamic Dataflow Programs in Heterogeneous Systems for Edge Computing\\nYear: 2021\\n\\nAbstract: The possibility of using the increasing computing power available in cloud infrastructures requires the development of new approaches for application software development and optimization. Emerging edge computing paradigms offer the possibility of reducing bandwidth needs and of optimizing latency, features particularly relevant for Big Data applications, by bringing computation closer to the user and to the data generation processes. However, edge computing approaches pose several challenges in terms of how to be able to efficiently take advantage of a distributed network of heterogeneous processing nodes. This paper deals with this problem by extending a dynamic dataflow software development framework and related design flow tools to support heterogeneous platforms. The paper describes the methodology steps for the synthesis of application software executing on heterogeneous CPU/GPU co-processing nodes. The steps do include the optimization of the communication between heterogeneous processing elements, a technique for the efficient mapping and parallelization of computation on independent GPU partitions, and the introduction of dynamic programming approach for leveraging the SIMD nature of GPU computing. To complete the methodology of seamless porting of dataflow software and partition on CPU or GPU computing nodes, an automated methodology for exploring the configuration space and to identify high performance working points is developed.\",\n \"Title: The impact of NFT profile pictures within social network communities.\\nYear: 2022\\n\\nAbstract: This paper presents an analysis of the role of social media, specifically Twitter, in the context of non-fungible tokens, better known as NFTs. Such emerging technology framing the creation and exchange of digital object, started years ago with early projects such as \\\"CryptoPunks\\\" and since early 2021, has received an increasing interest by a community of people creating, buying, selling NFT's and by the media reporting to the general public. In this work it is shown how the landscape of one class of projects, specifically those used as social media profile pictures, has become mainstream with leading projects such as \\\"Bored Ape Yacht Club\\\", \\\"Cool Cats\\\" and \\\"Doodles\\\". This work illustrates how heterogeneous data was collected from the Ethereum blockchain and Twitter and then analysed using algorithms and state-of-art metrics related to graphs. The initial results show that from a social network perspective, the collections of most popular NFTs can be considered as a single community around NFTs. Thus, while each project has its own value and volume of exchange, on a social level all of them are primarily influenced by the evolution of values and trades of \\\"Bored Ape Yacht Club\\\" collection.\",\n \"Title: A Benchmark of Entropy Coders for the Compression of Genome Sequencing Data\\nYear: 2022\\n\\nAbstract: Genomic sequencing data contain three different data fields: read names, quality values, and nucleotide sequences. In this work, a variety of entropy encoders and com-pression algorithms were benchmarked in terms of compression-decompression rates and times separately for each data field as raw data from FASTQ files (implemented in the Fastq analysis script) and in MPEG-G uncompressed descriptor symbols de-coded from MPEG-G bitstreams (implemented in the symbols analysis script). The result of this benchmark is then compared to the performance of CABAC, which is the encoder used in first edition of the ISO /IEC MPEG-G standard for all types of descriptors, since CABAC was the best performing in terms of compression rates for the three types of data, thus providing overall better compression rates compared to other entropy coders in total. However, in some use cases encoding and decoding speed might be of higher interest than compression, and for specific datasets, types of data, or descriptor streams, other entropy coders might provide higher speed and/or better compression performance than CABAC.\",\n \"Title: MPEG-G Reference-Based Compression of Unaligned Reads Through Ultra-Fast Alignments\\nYear: 2022\\n\\nAbstract: With the widespread application of next generation sequencing technologies, the volume of sequencing data became comparable to that of big data domains. The compression of sequencing reads (nucleotide sequences, quality values, read names), in both raw and aligned data, is a way to alleviate bandwidth, transfer, and storage requirements of genomics pipelines. ISO/IEC MPEG-G standardizes the compressed representation (i.e. storage and streaming) of structured, indexed sets of genomic sequencing data for both raw and aligned data. For the latter, reference-based compression is a strategy used to compress nucleotide sequences of sequencing reads by using alignment information to a reference sequence, which can be used to represent nucleotide sequences by storing the starting position of the alignment on the reference sequence, and the differences between the reference and the actual read. This general scheme is implemented in different ways by genomic data compressors, such as DeeZ, Quip, and CRAM, which apply to aligned reads.\",\n \"Title: A Capacitively-Coupled Chopper Instrumentation Amplifier for Implantable Bridge Sensor Systems\\nYear: 2022\\n\\nAbstract: This paper presents an energy and area efficient capacitively-coupled chopper instrumentation amplifier (CCIA) dedicated to implantable bridge sensor systems. Chopper stabilization is employed to decrease its offset and 1/f noise and the resulting ripple due to the up-modulated offset and 1/f noise is suppressed by a switched-capacitor ripple reduction loop. The gain of the instrumentation amplifier is defined by a programmable capacitive feedback network with a gain range from 40 V/V to 116 V/V, which is suitable for use with bridge sensors having different output voltages. The proposed CCIA has been fabricated in a standard 0.18 µm CMOS process. It achieves an input noise of 88.2 nV/√Hz, a worst-case input offset of 5 µV, and an output ripple of less than 185 μV. The CCIA occupies only 0.17 mm\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sup>\\n chip area and draws 3.3 μA current from a 1.2 V supply.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":98,"string":"98"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":250,"string":"250"}}},{"rowIdx":251,"cells":{"question_id":{"kind":"string","value":"Jianda Han"},"question":{"kind":"string","value":"Generate an abstract for the title \"Experimental study of cooperative obstacle avoidance between aerial and ground vehicles using multi-RFRs testbed.\" using the following items: 1) Multiple-Rotor-Flying-Robot\n2) IROS 2011\n3) Experimental platform\n4) New-designed\n5) Video summary"},"answer":{"kind":"string","value":"This manuscript gives a summary of the contributed video, submitted to IROS 2011, on a new-designed Multiple-Rotor-Flying-Robot experimental platform. © 2011 IEEE."},"correct_answer":{"kind":"string","value":"This manuscript gives a summary of the contributed video, submitted to IROS 2011, on a new-designed Multiple-Rotor-Flying-Robot experimental platform. © 2011 IEEE."},"documents":{"kind":"list like","value":["Title: UKF based estimation and tracking control of nonholonomic mobile robots with slipping\nYear: 2007\n\nAbstract: A kinematic model of tracked vehicles is established in this paper, in which both longitudinal and lateral slipping is considered and processed as three time-varying parameters. Unscented Kalman filter is then introduced to real time estimate the pose and slipping parameters jointly. A stable tracking control law for this nonholonomic system is proposed and the asymptotic stability is guaranteed by Lyapunov theory. Simulation results show the efficiency and robustness of the proposed method.","Title: Artificial Potential Guided Evolutionary Path Plan for Multi-Vehicle Multi-Target Pursuit.\nYear: 2004\n\nAbstract: Path planning for multi-vehicle multi-target pursuit (MVMTP) is studied in this paper. With respect to equal number of vehicles and obstacles, a global cost function (GCF) is proposed and an optimal one-vehicle-one-target-pair appointment is specified based on the GCF. The artificial potential (AP)-guided evolutionary algorithm (EA) is used by each appointed pair to search the path that will allow the vehicle to catch the target at a specified criterion while avoiding obstacles. Both the targets and obstacles are moving in the environment, and the pair appointment can be updated regularly according to the snapshot of the uncertain environment. The integration of AP into EA is intended to achieve a convergent, fast and efficient trajectory searching mechanism that can be installed in real time. ©2004 IEEE.","Title: A Double-Side Filter Based Power Line Recognition Method For Uav Vision System\nYear: 2013\n\nAbstract: Automatic power line recognition from cluttered background is an important and challenging task for a vision based unmanned aerial vehicles (UAVs) power line inspection system. In this paper, we propose a power line recognition method based on liner object enhancement and parallel lines constraint. A new double-side filter is proposed to enhance the power lines, and then the radon transform is used to find the parallel lines as the power line recognition results. Our experiments on real image data captured from UAV demonstrate our method is effective for automatic power line recognition.","Title: The New Evolution For Sia Rotorcraft Uav Project\nYear: 2010\n\nAbstract: This paper describes recent research on the design, implement, and testing of a new small-scaled rotorcraft Unmanned Aerial Vehicle (RUAV) system-ServoHeli-40. A turbine-powered UAV weighted less than 15 kg was designed, and its major components were tested at the Shenyang Institute of Automation, Chinese Academy of Sciences in Shenyang, China. The aircraft was designed to reach a top speed of more than 20 mps, flying a distance of more than 10 kilometers, and it is going to be used as a test-bed for experimentally evaluating advanced control methodologies dedicated on improving the maneuverability, reliability, as well as autonomy of RUAV. Sensors and controller are all onboard. The full system has been tested successfully in the autonomous mode using the multichannel active modeling controller. The results show that in a real windy environment the rotorcraft UAV can follow the trajectory which was assigned by the ground control station exactly, and the new control method is obviously more effective than the one in the past year's research.","Title: Tracking Control of Unmanned Trimaran Surface Vehicle: Using Adaptive Unscented Kalman Filter to Estimate the Uncertain Parameters\nYear: 2008\n\nAbstract: This paper proposes an adaptive unscented Kalman filter (UKF) based tracking controller to force underactuated nonlinear autonomous ships to follow a reference path under constant disturbances induced by wave, wind and ocean-current. The controller development is based on MIT based UKF and backstepping techniques. The AUKF is used to update the estimation of the uncertain parameters online to avoid the parameters' drift due to time-varying added mass matrices. Along the way of tracking control, we obtain a new stability result for nonlinear underactuated systems with non-vanishing uncertainties. Simulations conducted with respect to the tracking control of unmanned ship illustrate the effectiveness of our proposed controller.","Title: Helicopter velocity tracking control by adaptive actor-critic reinforcement method\nYear: 2011\n\nAbstract: A robotic helicopter is an aircraft equipped with a sensing, computing, actuation, and communication infrastructure that allows it to execute a variety of tasks with autonomous mode. In this paper, we present an adaptive actor-critic reinforcement method to obtain near optimal controller for small autonomous helicopter. A network based on Q-value performs the critic and is trained by SARSA algorithm. A BP neural network, which is the actor network, generates control signal of helicopter dynamics. First, the proposed actor-critic reinforcement controller is introduced, then the algorithm is applied to an unmanned helicopter known as a highly nonlinear and complex system and the simulation results are presented.","Title: Aggressive Manuevering of Unmanned Helicopters: Learning from Human Based on Neural Networks.\nYear: 2012\n\nAbstract: Teaching by Showing control of a small helicopter's aggressive maneuvering often needs inner aided controllers based on helicopter's dynamics, which is very complex to identify. In this paper, a neural network based control is proposed, based on the identification of the relationship between the pilot's control and flight states, and it is a model-free control method. Flight test is done in simulation environment based on real flight data. The results show the effectiveness of the neural network based controller for aggressive flight control.","Title: The analysis and synthesis of PID controller based on closed loop response characteristics\nYear: 2012\n\nAbstract: In this paper, a new PID parameter tuning method is proposed. First, extensive analysis of the PID frequency properties is conducted. Based on the analysis results, the concept of characteristic frequency of the PID controller is proposed, which builds a relationship between the PID parameters and the oscillation characteristics of the closed loop response of the PID control system. This relationship makes it possible to adjust the PID parameters according to the oscillation characteristics of the closed loop response of the PID control system. Based on the characteristic frequency of the PID controller and the corresponding analysis results, three tuning rules of the PID parameters are proposed, which are based on the characteristics of the closed loop response. The merits of these tuning rules are: only the characteristics of the closed loop response of the control system are required in the tuning process, while the system model of the controlled object is not required. The effectiveness of these tuning rules is verified by the simulation results for several models of the controlled objects.","Title: Trajectory Planning Of Manipulator For A Hitting Task With Autonomous Incremental Learning\nYear: 2007\n\nAbstract: A new approach based on genetic algorithm (GA) and autonomous mental development for trajectory planning of robot manipulator is presented in this paper. The trajectory for the manipulator is optimized by the GA. To make the trajectory planning used in real time application, a developmental learning algorithm is proposed to generate an incremental hierarchical discriminating regression (IHDR) tree to form the mapping from the state space to the action space. Just like the human brain from infancy to adulthood, the algorithm develops its cognitive and behavioral skills through online learning from the samples obtained from the GA-based method. When the IHDR tree is generated, it can perform the trajectory planning in real time by retrieving in its knowledge database.","Title: Kinematics/statics and workspace analysis of a 3-leg 5-dof parallel manipulator with a upu-type composite active constrained leg\nYear: 2013\n\nAbstract: A novel 3-leg 5-DoF parallel manipulator PM with a UPU-type composite active constrained leg is proposed and its kinematics and statics are analyzed systematically. First, the formulae are derived for solving the inverse/forward displacements, inverse/forward velocities, and active/constraint forces. Second, the formulae are derived for solving inverse/forward accelerations. Third, a simulation mechanism of this PM is created and its workspace is constructed and analyzed. Finally, the analytic results are verified by its simulation mechanism.","Title: Hierarchical projection regression for online estimation of elbow joint angle using EMG signals.\nYear: 2013\n\nAbstract: Exoskeletons offer great facilities to the elderly and disabled people with respect to extending their moving ranges and reacting to certain physical activities. Electromyogram (EMG) signals, which are derived from the neuromuscular system, provide an important access to the human-robot interface. On one hand, EMG signals can be used for real-time estimation of the motion intention of human body, e.g., the current joint angle status. On the other hand, however, the process of the mass EMG data, which are captured instantaneously from skin surface, challenges the state-of-the-art technology. Because its non-stationary and randomness, it is difficult to extract the valuable and stable features from the raw EMG signals. This paper investigates into the learning process of high dimensional EMG signals with a hierarchical mechanism that projects the original data into a lower feature space to achieve a local refined mapping from the EMG signals to the motion states of the human body. This hierarchically projected regression algorithm constructs incrementally a tree-based knowledge library, whose components represent local regression models. The components will be retrieved online efficiently and contribute to the estimation of the motion states. A great number of experiments are carried out to evaluate the accuracy of this novel algorithm. © 2012 Springer-Verlag London Limited.","Title: Trajectory Generation in Relative Velocity Coordinates Using Mixed Integer Linear Programming with IHDR Guidance\nYear: 2007\n\nAbstract: Mixed-integer linear programming (MILP) for trajectory generation of mobile robot suffers from nonlinear constraints due to complex obstacle contours and dynamic environment. In this paper, firstly, we introduce a relative velocity coordinates MILP (RVCs-MILP) for solving the nonlinear constraints problem in the trajectory generation of the target pursuit and multiple-obstacle avoidance (TPMOA). The computational load of the RVCs-MILP does not increase with the complexity of obstacle contour but only relates to the number of the obstacles. It can be applied in real time when the number of the obstacles is small. For the large numbers of obstacles avoidance, further, we propose an IHDR based online learning mechanism. It sets up a \"scenario-action mapping\" knowledge base by continuously offline training and online updating. For a trajectory generation task, it will search a best match path of the current state in the knowledge base according to the external environments and the state of the robot in real time. Simulations are presented in comparison with the evolution algorithms (EA) and IHDR. The former shows significant improvement in a number of aspects. The latter confirms the validation of the proposed IHDR methods.","Title: Modeling a Small-size Unmanned Helicopter Using Optimal Estimation in The Frequency Domain\nYear: 2010\n\nAbstract: In this paper, a semi-decoupled state space model of a small-size helicopter is developed for hovering conditions in order to simplify the model identification process. An optimal estimation algorithm in frequency domain is proposed and implemented to estimate the parameters in the state space model using real flight data collected from a SERVOHELI-40 small-size unmanned helicopter. The accuracy of the identified model is verified by simulation in time domain, using a different set of hovering flight data. The results have shown the accuracy of the developed semi-decoupled model and the effectiveness of the proposed optimal estimation algorithm in frequency domain.","Title: Dynamical vision sensors based active cooperative observation in three dimensional environment\nYear: 2013\n\nAbstract: Vision based observation of a moving target is one of the important problems and hot issues of mobile robot system. Dynamical vision sensors which is constituted with multiple robots to obtain improved observational results has been shown to be a good substitution of single vision sensors. Thus, a new active cooperative observation (ACO) method based on two dynamical vision sensors is proposed. The most characteristics of the proposed method is that data fusion and path planning algorithm are simultaneously implemented and combined with each other by the optimal observation formation so that the influence of relative positions among MVSs and target on the cooperative observation result can be fully considered to improve the observation result. Finally, for verifying the validity and feasibility of the proposed method, experiments on a multiple rotor flying robots test-bed are conducted and analyzed, respectively.","Title: Decentralized receding horizon control for multiple unmanned helicopters considering dynamics model\nYear: 2009\n\nAbstract: In this paper, the formation flight of multiple Unmanned Helicopter (UH) systems is researched and a new decentralized receding horizon formation control algorithm is supposed. The formulation of formation control problem is firstly given where a local tracking controller for each helicopter system is supposed and the flight trajectories are taken as optimizing variables. Secondly, full dynamics of UH system is introduced into the formation control algorithm by a new concept of Formation Control Lyapunov Functions (FCLF). Subsequently, the convergence of the proposed formation control algorithm is ensured by combining the concept of FCLF and some constraints with respect to the optimized variables. Finally, in order to verify the feasibility and validity of the proposed algorithm, the formation flight simulations of 3 UH systems are conducted.","Title: The ServoHeli-20 Rotorcraft UAV Project\nYear: 2010\n\nAbstract: This paper describes research on the design, implement and testing of a small-scaled rotorcraft unmanned aerial vehicle (RUAV) system - ServoHeli-20. A turbine-powered UAV weighted less than 10 kg was designed, and its major components tested by a group of undergraduate students at Shenyang Institute of Automation, Chinese Academy of Sciences in Shenyang, China. The aircraft was designed to reach a top speed of more than 20 mps and fly a distance of more than 10 kilometers and then is going to be used as a testbed for experimentally evaluating advanced control methodologies dedicated on improving the maneuverability, reliability as well as autonomy of RUAV. Sensors and controller are implemented onboard. The full system has been tested successfully in the autonomous mode using the multi-channel decoupling PID controller. The results show that the rotorcraft UAV can follow the trajectory which assigned by the ground control station exactly in the real windy environment.","Title: Binocular Based Moving Target Tracking for Mobile Robot\nYear: 2009\n\nAbstract: Moving target tracking is an important application of computer vision. A binocular based method is presented for mobile robot to track target reliably under the effect of occlusion, transform and rotation in unstructured environment. Point features are extracted for representing the target and environment background under middle distortion, and then are matched and tracked through consecutive stereo frames by our improved MNCC algorithm. The point features are reconstructed and utilized to estimate the relative motion by Least-Square algorithm. Because the relative motion between the point features of target and robot is inconsistent to that of environment background and robot, the point features of environment background and the errors in feature tracking are removed by RANSAC algorithm. Experiment results validate the efficiency of our method.","Title: Rotorcraft UAV actuator failure detection based on a new adaptive set-membership filter\nYear: 2012\n\nAbstract: Actuator failure detection method based on a new Adaptive Extended Set-Membership Filter (AESMF) is proposed for Rotorcraft Unmanned Aerial Vehicle (RUAV). The AEMSF proposed in this paper is based on MIT method to optimize the set boundaries of process noises which may be incorrect in modeling or time-variant in operation; estimation stability and boundaries accuracy can be improved compared to the conventional ESMF. Actuator Healthy Coefficients (AHCs) is introduced into the dynamics of RUAV to denote the actuator failure model. Based on AESMF, online estimation of the AHCs can be obtained along with the flight state. With the estimated AHCs, actuator failure can be detected as soon as possible which provide valuable information for fault tolerant control. Efficiency and improvement of this method compared with other online parameters estimation methods is demonstrated by simulation using ServoHeli-20 model.","Title: A new real-time algorithm for off-road terrain estimation using laser data.\nYear: 2009\n\nAbstract: Gaussian mixture algorithm (GMA) is an effective approach for off-road terrain estimation, but still suffers from some difficulties\n in practical applications, such as complex calculation and object abstraction. In this paper, GMA ismodified to improve its\n real-time performance and to provide it with a potential ability of obstacle detection. First, a selection window is designed\n based on the dominant-ellipse-principle to limit the probability distribution area of each measurement point, therefore avoiding\n the calculation on the cells outside the dominant ellipse. Second, a clustering approach is proposed in order to distinguish\n objects efficiently and decrease the operation area of one laser scan. Third, a virtual point vector is introduced to further\n reduce the computational load of the mean square error matrix. The modified GMA is experimented on a tracked mobile robot,\n and its improved performance is shown in comparison to the original GMA.","Title: Feedback control for yaw angle with input nonlinearity via input-state linearization\nYear: 2006\n\nAbstract: This paper discusses the yaw control of small-size unmanned helicopter. The yaw dynamics of helicopter involve input nonlinearity, time-varying parameters and the couplings between main and tail rotor. With respect to such a complicated dynamics, the normal PID control is difficult to realize good tracking performance while maintaining stability and robustness simultaneously. In this paper, a valid control is proposed by applying the derivative of the nonlinear function, the original system is to be extended a new system with a pseudostate variable. This approach makes it possible to avoid using the inverse of the nonlinear function and reduces the calculation load. The simulation results further demonstrate the improvements of the proposed algorithm.","Title: A Review on Fault Diagnosis and Fault Tolerant Control Methods for Single-rotor Aerial Vehicles\nYear: 2014\n\nAbstract: Faults or failures are inevitable to occur and their prompt detection and isolation are essential for the dependability of various systems and for avoiding damages to the system itself, persons and the environment. Therefore, the safety of helicopter platforms have attracted the attention of many researchers in the past two decades. In order to deal with these problems, this paper presents an overview of the recent development and current researches in the field of fault diagnosis, including analytical/model-based, signal processing-based and knowledge-based techniques, and also passive/active fault- tolerant control approaches. Among various helicopters, single-rotor aerial vehicles, i.e. manned helicopters, unmanned helicopters, two and three degree-of-freedom unmanned helicopter experimental platforms, are considered for providing an overall picture of the fault diagnosis and fault-tolerant control approaches based on the review of journal articles in last two decades, conference articles in last several years and some books.","Title: Design And Implement Of A Rotorcraft Uav Testbed\nYear: 2006\n\nAbstract: This paper describes recent research on the design and implement of a small-scaled rotorcraft Unmanned Aerial Vehicle (RUAV) system. This platform is going to be used as a testbed for experimentally evaluating advanced control methodologies dedicated on improving the maneuverability, reliability as well as autonomy of RUAV. Sensors and controller are implemented onboard. The full system has been tested successfully in the remote-controlled mode. A control scheme based on a simplified thrust-torque model, which is for the initial flight test, is also presented.","Title: A New Fast Histogram Matching Algorithm For Laser Scan Data\nYear: 2008\n\nAbstract: This paper presents a new fast histogram matching algorithm for tracking the position and orientation of robots without the help of any odometers. Histogram avoids extracting geometrical primitives from the sensor data, acts independently from odometers, and is easy to be implemented. Here, the authors employ it to analyze laser scan data. A new concept named \"hierarchical histogram structure\" is introduced for constructing and matching histograms. This structure makes full use of the information in a laser scan and speeds up the histogram matching to a satisfying level. Computational complexity analysis and experiments show the feasibility of the new algorithm both mathematically and factually.","Title: A General Closed-Loop Framework for Multi-dimensional Sequence Processing.\nYear: 2012\n\nAbstract: A novel closed-loop framework for multidimensional sequence processing is proposed in this paper. Traditional sequence-driven models are always forward, so no information is feedback to correct their outputs, which may deviate from the true values gradually due to the estimation error accumulating. To overcome the problem, the multidimensional vector in the input sequence is divided into two vectors based on its data attribute. One vector sequence generated from the original input sequence is considered as the new input sequence, and the other is considered as the measurement output sequence. The original output sequence is treated as the state sequence. Then, a closed-loop model in the state-space form is constructed, with which the states can be estimated online by filtering algorithms The feasibility of the proposed framework has been verified by using the robot inverse kinematics.","Title: LP-based Optimal Path Planning in Acceleration Space\nYear: 2006\n\nAbstract: This paper proposed acceleration space linear programming (ASLP) method for the path planning of target pursuit and obstacles avoidance (TPOA) problem in dynamic and uncertain environment. The acceleration space for TPOA problem is defined and LP algorithm is introduced into it. LP is a powerful tool for optimization but exhibits weakness when there exist nonlinear constraints or objective function. In the proposed acceleration space, the constraints and objective function of TOPA problems are inherently described as linear inequalities that can be directly solved by LP. Also, the complexity in obstacle contour does not increase the computational burden of the ASLP. Simulations are conduced with respect to the TPOA scenario including one moving target and multiple moving obstacles. The results obtained by ASLP are presented and compared with those of artificial potential guided evolution algorithm (APEA). Significant superior is demonstrated in many aspects by the comparison.","Title: A Full-functional Simulation and Test Platform for Rotorcraft Unmanned Aerial Vehicle Autonomous Control.\nYear: 2012\n\nAbstract: In this paper, a prototype Hardware in the loop (HIL) simulation and test platform for ServoHeli40 and ServoHeil120 rotorcraft unmanned aerial vehicles have been developed in Shenyang Institute of Automation, Chinese Academy of Science. This simulation system includes a 3D flight and scenery simulator, a flight control systems, a ground control station, and a RC pilot controller. Based on a semi-decoupled flight dynamic model, which is acquired from a frequency domain system identification method using real flight hovering data, an autonomous PID controller is implemented and verified in both simulation and real flight tests. To fulfill agricultural, marine and industrial applications, the application oriented functionalities of the flight control system has been developed and fully tested before deployment in the field. And it is also beneficial to further research such as human factors in operating UAV systems and UAV task load issues. © 2013 Springer-Verlag.","Title: Noise Covariance Identification Based Adaptive Ukf With Application To Mobile Robot Systems\nYear: 2007\n\nAbstract: A novel adaptive Unscented Kalman Filter (UKF) based on dual estimation structure is proposed. The filter is composed of two parallel master-slave UIKFs, while the master one estimates the states and the slave one estimates the diagonal elements of the noise covariance matrix for the master UKF. By estimating the noise covariance online, the proposed method 1 able to compensate the errors resulting from the change of the noise statistics. Such a mechanism improves the adaptive ability of the UKF and enlarges its application scope. Simulations conducted on the dynamics of an omni-directional mobile robot indicate that the performance of the adaptive UKF is superior to the standard one in terms of fast convergence and estimation accuracy.","Title: Three-dimensional path planning for unmanned aerial vehicle based on linear programming\nYear: 2012\n\nAbstract: In this paper, an approach based on linear programming (LP) is proposed for path planning in three-dimensional space, in which an aerial vehicle is requested to pursue a target while avoiding static or dynamic obstacles. This problem is very meaningful for many aerial robots, such as unmanned aerial vehicles. First, the tasks of target-pursuit and obstacle-avoidance are modelled with linear constraints in relative coordination according to LP formulation. Then, two weighted cost functions, representing the optimal velocity resolution, are integrated into the final objective function. This resolution, defined to achieve the optimal velocity, deals with the optimization of a pair of orthogonal vectors. Some constraints, such as boundaries of the vehicle velocity, acceleration, sensor range, and flying height, are considered in this method. A number of simulations, under static and dynamic environments, are carried out to validate the performance of generating optimal trajectory in real time. Compared with ant colony optimization algorithm and genetic algorithm, our method has less parameters to tune and can achieve better performance in real-time application.","Title: An Adaptive UKF Algorithm and Its Application in Mobile Robot Control\nYear: 2006\n\nAbstract: In order to improve the performance of the UKF a novel adaptive filter method is proposed. The error between the covariance matrices of innovation measurements and their corresponding estimations/predictions is utilized as the cost function. Based on the MIT rule, an adaptive algorithm is designed to online update the covariance of the process uncertainties by minimizing the cost function. The updated covariance is further fed back into the normal UKF. Such an adaptive mechanism is intended to compensate the lack on the priori knowledge of process uncertainty distribution and improve the performance of UKF for the applications such as active state and parameter estimations. Simulations are conducted with respect to the dynamics of an omni-directional mobile robot, and the results obtained by the proposed AUKF are compared with those by normal UKF to demonstrate the effectiveness and improvements.","Title: Dynamic Feedback Tracking Control Of Tracked Mobile Robots With Estimated Slipping Parameters\nYear: 2008\n\nAbstract: The trajectory tracking control problem of a tracked vehicle with slipping is considered in this paper. The slipping effects are analyzed and modeled as three time-varying parameters, which can be estimated simultaneously with robot's pose using nonlinear estimators such as unscented Kalman filter. Dynamic feedback linearization integrated with a globally exponential stabilizing state feedback is applied to achieve the tracking control objective. Simulation results are provided to demonstrate the effectiveness of proposed method.","Title: Robust H-2 Control With Adaptive Mechanism For The Yaw Control Of Small-Scale Helicopter\nYear: 2006\n\nAbstract: This paper presents a robust H-2 controller design approach to the yaw control of a small-scale helicopter mounted on an experimental platform. The yaw dynamic system is linearized into a linear system, which is modelled by an affine uncertainty model. A new robust H-2 feedback controller with adaptive mechanisms is proposed for the linear system. The feedback gains are obtained by the solutions of a series of linear matrix inequalities (LMIs). The design approach reduces conservatism inherent in robust control with a fixed gain controller and improves performances in time-response. Numerical simulations illustrate the effectiveness of the proposed methods.","Title: An Adaptive Threshold Neural-Network Scheme for Rotorcraft UAV Sensor Failure Diagnosis\nYear: 2007\n\nAbstract: This paper presents an adaptive threshold neural-network scheme for Rotorcraft Unmanned Aerial Vehicle (RUAV) sensor failure diagnosis. The approach based on adaptive threshold has the advantages of better detection and identification ability compared with traditional neural-network-based scheme. In this paper, the proposed scheme is demonstrated using the model of a RUAV and the results show that the adaptive threshold neural-network method is an effective tool for sensor fault detection of a RUAV.","Title: ESMF based multiple UAVs active cooperative observation method in relative velocity coordinates\nYear: 2009\n\nAbstract: Based on extended set-membership filter (ESMF) and the path planning method in relative velocity coordinates (RVCs), a new 3D multiple Unmanned Aerial Vehicle (UAV) systems active cooperative observation method, high precision cooperative observing a moving target by proper planning the behavior of each member vehicle, is proposed. The new method combines the ESMF based cooperative observation method and the LP-based trajectory generation method in RVCs, where the ESMF based cooperative method is used to obtain the moving target's motion state which is further used as part of the cost function to plan the UAV's behavior by using the planning method in RVCs. The contribution of this paper is: (1) the computational burden of the proposed cooperative algorithm is comparable to single ESMF algorithm; (2) the high precision observation of moving target is always obtainable by considering the optimal observation condition during trajectory planning; (3) the planning algorithm in RVCs, where the trajectory planning can be modeled as a LP problem, is used to optimize the UAV's behavior, thus, in company with (Gu, et al; 2006), the fast application of the new proposed active cooperative observation method is desirable. Finally, the simulations in 3D environments are conducted to verify the feasibility and validity of the method.","Title: A New Nonlinear Controller Design Method Based on Control Lyapunov Function\nYear: 2006\n\nAbstract: A new formulation of nonlinear controller design method based on control Lyapunov function, called generalized pointwise min-norm (GPMN) controller, is introduced in this paper by generalizing the pointwise min-norm (PMN) controller presented by Freeman etc. And combining the GPMN controller with design-via-linearization approach of nonlinear system, we can obtain a new nonlinear controller design method, which can enlarge the stability region of the design-via-linearization approach and reserve the local performance of it. And a respectively robust and constrained version of this kind of controller is also introduced by considering both model uncertainty and input constraints.","Title: Design, implementation and experimental tests of a new generation of Antarctic rover\nYear: 2012\n\nAbstract: The Arctic and Antarctic, as the harshest environments on the earth, are of great importance to the nation. The extreme environments can be harmful, even fatal, to human beings and mobile robots. To execute missions on the Antarctic in place of human, the State Key Laboratory of Robotics of Shenyang Institute of Automation, Chinese Academy of Sciences has designed three generations of Antarctic rovers. The hardware and software design and implementation of the third generation of Antarctic rover, which has been tested on the Antarctic during the 28th Chinese National Antarctic Research Expedition in 2011, will be presented in this paper. The preliminary experimental results, as introduced in the last part of the paper, suggest that the design and implementation of the hardware and software system can ensure efficiency and reliability of the rover working on the Antarctic.","Title: A solution of mixed integer linear programming for obstacle-avoided pursuit problem.\nYear: 2008\n\nAbstract: In this paper the path planning for obstacle-avoided pursuit problem (OAP) is studied. The OAP models based on the mixed integer linear programming (MILP) is presented. In the OAP models, the dynamic equation of mass point with linear damping is taken as the state equation of vehicle's motion. Integer variables are used to describe the relative position of vehicle and obstacles. \"Expansible Target Size\" is proposed to describe the pursuit process for target step-by-step. \"Pursuit Direction\" of vehicle is defined. The Isometric Plane Method selected integer variables is used to solve MILP pursuit problem. How to select the integer variables of inner point is also given. Finally, simulations are given to show the efficiency of the method.","Title: Design and implementation of a compact RUAV navigation system.\nYear: 2010\n\nAbstract: A small, low-cost, light-weight, and compact GPS/INS navigation system for a Rotorcraft UAV (RUAV) was designed and implemented on an ARM9 LPC3250 platform, and the process is discussed in this paper. Based on the characteristics of the sensors, a two-stage Extended Kalman Filter (EKF) is embedded to estimate the flight states, get rid of online noise, and fed back the results to the flight controller. Some practical problems about realizing the algorithm have been addressed. The full system has been tested successfully on a ServorHeli-40 RUAV platform. Based on this navigation system, further research in navigation and control theory can be implemented and tested experimentally. © 2010 IEEE.","Title: Unsupervised progressive structure-from-motion for unordered images\nYear: 2012\n\nAbstract: A robust progressive structure from motion (PSFM) method is proposed for unordered images. Our method can reduce accumulative error efficiently during scene dense recovery and camera motion estimation. The whole unordered images are divided into two classes: key frames and non-key frames. For key frames, superior features are selected and tracked to initialize the parameters of PSFM reliably and reduce the accumulative errors. During the implementation of PSFM, several novel and efficient strategies are proposed to detect the parameter estimation errors and remove the outliers in feature tracking. A local on-demand scheme is proposed to dramatically reduce the computing cost of sparse bundle adjustment. The experimental results from different scenes show that our method is efficient and robust in scene dense recovery and camera motion estimation.","Title: Hovering control of UAV based on autonomous mapping approach.\nYear: 2010\n\nAbstract: The autonomous learning capability of UAV (unmanned aerial vehicle) has gained more and more attentions of researchers. As far as helicopter steering is concerned, instead of calculating dynamics of UAV in a relative short interval, pilots just take their experience and consciousness instantaneously, known as similar status has similar action, to keep the helicopter hovering. The experience and the consciousness of pilots store the mapping from the similar environment to the corresponding similar decisions. Motivated by the process, we establish the UAV mapping base from environment to decision with IHDR (Incremental Hierarchical Discriminant Regression) algorithm. UAV learns to build the mapping relation offline and online alternatively. The retrieval process from the mapping base has higher efficiency for its less mathematics complexity. Simulation results show that the approach we proposed in this paper has better performance than traditional neural network. © 2010 IEEE.","Title: Adaptive Robust Control Techniques Applied to the Yaw Control of a Small-scale Helicopter\nYear: 2006\n\nAbstract: This paper presents a new robust controller design approach to the yaw control of a small-scale helicopter mounted on an experimental platform. The yaw dynamic system is linearized into a linear system, which is modelled by an affine uncertainty model. We proposed a novel robust Hinfin feedback controller with adaptive mechanisms for the linear system with guaranteed control performances. The feedback gains are obtained by the solutions of a series of linear matrix inequalities (LMIs). The design approach reduces conservatism inherent in robust control with a fixed gain controller and improves performances in time-response. Numerical simulations illustrate the theoretical results","Title: Acceleration Feedback Control For Direct-Drive Motor System\nYear: 2000\n\nAbstract: In this study, classical PD control for direct drive motor system is enhanced to suppress disturbing torque by incorporating an acceleration feedback loop. This intends to achieve a stable and high stiffness control without the need of adjusting the PD controller; either the structure or the parameters. The acceleration feedback control is presented with a focus on designing the acceleration closed-loop in terms of its stability and ability in resisting the dynamic disturbances. The sensing and modeling of angular acceleration via servo-type linear accelerometers is dealt with in viewpoint of practical implementation Extensive experiments are conducted on the second joint of a three-link direct drive robot. Results are given against those obtained by classical PD control without the acceleration feedback loop, to mainly investigate the ability of the acceleration feedback control in resisting disturbing torque, and its influence to the conventional PD control.","Title: A novel HCI based on EMG and IMU\nYear: 2011\n\nAbstract: The technology of human-computer interaction (HCI) is developing rapidly in tandem with the advancement of information and biological technologies. Many new types input device are introduced into this field; some of them are aimed to benefit special groups of people like old or disabled persons. In the meantime, Electromyography (EMG) and Inertia Measure Unit (IMU) have been readily available and extensively applied in control systems in many fields. In this paper, we propose a novel EMG-IMU based mouse controller that controls cursor movements based on IMU signals. The displacement of the cursor is determined by integrating the acceleration signal from the IMU, which moves with the operator's arm. The mouse operations such as left click, right click and wheel scroll, are commanded through EMG signals. The pattern recognition algorithm, Linear Discriminant Analysis (LDA), is adopted to classify the EMG data into several clusters, which correspond to the pre-defined mouse operations. Experimental results have indicated that the proposed mouse controller can achieve an accuracy of 88%.","Title: Experimental study of vision sensor based multiple robots active cooperative observation using multi-RFRs testbed\nYear: 2011\n\nAbstract: An experimental study of an active cooperative observation approach based on Extended Set-Membership Filter (ESMF) is completed. In the experiment, the two RFRs can keep the optimal observation formation while achieving the cooperative observation so that the observation accuracy is improved further. The most attracting advantages in this video is that the experimental results on the testbed showed the proposed method can achieve data fusion well to improve the observation accuracy and the real time performance and observation accuracy can meet the requirement of on-line application.","Title: Active Model-Based Predictive Control and Experimental Investigation on Unmanned Helicopters in Full Flight Envelope\nYear: 2013\n\nAbstract: For the control of unmanned helicopters in full flight envelope, an active model based predictive control scheme is developed in this brief. Dynamics in full envelope is modeled, with uncertainties represented by the system model error and process noise. The model error depends on both helicopter dynamics and flight mode, and the process noise is assumed unknown but bounded. Based on the set-membership filter, an active modeling based stationary increment predictive control, based on the estimated model error and its boundary to optimally compensate the model error, as well as the aerodynamics time delay, is proposed. The proposed method has been implemented on the ServoHeli-40 unmanned helicopter platform and experimentally tested; the results have demonstrated its effectiveness.","Title: Laser scan matching using multiplex histograms with feature components\nYear: 2009\n\nAbstract: A new laser scan matching algorithm is proposed in this paper. By constructing multiplex histograms, the new algorithm offers a simple way for importing geometrical features into the histogram method, obtaining more geometrical information from the laser scan data, and carrying out more accurate matching results. Also, an optimal maximum selection mechanism is employed to filter out the incorrect matching results, which further guarantees the matching precision. With the satisfactory matching results, the new algorithm shows a promising application prospect to the self-localization of robots. Experiments are performed to prove the feasibility and accuracy of the new algorithm.","Title: Energy-aware utility optimisation for joint multi-path routing and MAC layer retransmission control in TDMA-based wireless sensor networks\nYear: 2013\n\nAbstract: This paper formulates a novel energy-aware utility optimisation EUO problem for joint multi-path routing and medium access control MAC layer retransmission control in time division multiple access TDMA-based wireless sensor networks WSNs. As the EUO problem is non-convex and inseparable, we propose a heuristic method called Successive Alternating Convex Approximation SACA to approximately solve the problem. More precisely, we decompose the EUO problem into two alternating convex sub-problems, namely energy-aware multi-path routing and retransmission control. On one hand, given the time slot allocation, the multi-path routing balances the energy consumption within WSNs. On the other hand, provided the traffic distribution, retransmission control enhances the data reliability in the most energy-efficient way. These two sub-problems are solved recursively by means of dual decomposition. The sequence of optimal solutions to these two sub-problems is shown to converge to some steady-state point that approximates a solution to the EUO problem.","Title: Dynamic Tracking Of Minimally Invasive Spine Surgery Robot\nYear: 2013\n\nAbstract: In order to exhibit the surgery instruments in intraoperative image, the tracking system must be introduced so that it may finally achieve the image guide surgery on minimally invasive spine surgery (MISS). To exhibit the tip of the instrument, the transform of the CARM(a device which generates X-ray images) and CT image, the transform of the world and CARM. The more transforms of different space happen, the more errors will be introduced into the system. This paper is focused on the surgery robot tracking problem, especially for the tracking of the position and posture of the surgery instruments. We introduce a method which could establish the robot model of the surgery and show the projection of the surgery instruments on intraoperative images which could help surgeon estimate the relative position of the surgery instrument and patient's spine.","Title: Motion planning for flexible needle in multilayer tissue environment with obstacles\nYear: 2012\n\nAbstract: Flexible needle with bevel tip offers greater mobility for puncture surgery. This would expand the scope of the puncture surgery. However, motion planning for flexible needle is still a challenge due to its non-holonomic property and the complicated interactions with soft tissues. In this paper, a multilayer tissue model is constructed to simulate human tissue, and a dynamic programming is employed to plan the motion of flexible needle in the multilayer environment. In order to improve the security of the puncture process, the obstacles are fuzzed up. Then, an optimal algorithm is developed to determine a more suitable puncture angle. In addition, to deal with more complex environment, we develop a reverse algorithm to confirm the entry point in line with the target. Finally, we take some simulations to verify the proposed algorithms, and analyze the results.","Title: Kinematics, Statics And Stiffness Analysis Of N(4-Sps+Sp) S-Pm\nYear: 2012\n\nAbstract: A novel n(4-SPS+SP) serial-parallel manipulator (S-PM) formed by n 4-SPS+SP PMs with four degrees of freedom (DOF) connected in series is proposed in this paper. The kinematics, statics and stiffness model of this serial-PM is established. First; the forward kinematics of 4-SPS+SP (spherical joint-prismatic joint-revolute+spherical joint-prismatic joint) PM is derived and the kinematics of n(4-SPS+SP) S-PM is studied combined with the kinematics result of single 4-SPS+SP PM. Second, the statics; deformation and stiffness of n(4-SPS+SP) S-PM are studied. Finally, an analytically solved example is given for 3(4-SPS+SP) formed by three 4-SPS+SP PMs. The method for this mechanism is fit for other S-PMs.","Title: Design and implementation of multiple-rotorcraft-flying-robot testbed\nYear: 2011\n\nAbstract: In this paper, a multiple-rotorcraft-flying-robot (MRFR) testbed is introduced. Firstly, physical structure, as well as hardware and software system, is described in detail. Subsequently, in order to realize the autonomous flight of each single rotorcraft-flying-robot (RFR), modeling, identification and flight control experiments are conducted. Then, formation flying demonstration is presented to verify the basic functions of the new-designed MRFR testbed. Finally, two points should be emphasized: 1) both cooperation/coordination algorithm of MRFR and advanced flight control algorithm of single RFR can be verified on this testbed; 2) experiments on this testbed can approach real flight test much better because three real RFR systems are used.","Title: Theoretical and experimental study of uncertain set based moving target localization using multiple robots.\nYear: 2011\n\nAbstract: In this paper, multiple robots cooperation based moving target localization problem is researched. Different from traditional statistics based architecture, the concept of uncertain set is utilized in this paper to formulate the so called Cooperative Enhanced Set Membership Filter based cooperative localization algorithm. One of the most attracting advantages of this method is that it assumes the measurement errors are modeling as unknown-but-bounded set, instead of requiring the errors' covariance to be obtainable beforehand, which is general in statistics based algorithm, such as Kalman Filter and Particle Filter. Furthermore, some strategies, which is originated from the update process of the ESMF algorithm itself, are proposed to improve the computational efficiency and localization accuracy. Finally, an original experimental scenario is designed with respect to an indoor multiple-rotorcraft-platform and the results are listed out and analyzed in detail to verify the feasibility and validity of the proposed algorithm. © 2011 IEEE.","Title: Feasibility of EMG-based ANN controller for a real-time virtual reality simulation\nYear: 2012\n\nAbstract: Estimation of the joint angle from the surface electromyography (sEMG) is a quite complex task due to the complicated relationship between the kinematical variables and the raw sEMG. In this paper, we build a sEMG-to-motion model with the artificial neural network (ANN). EMG features, including Integral of absolute value (IAV), Zero crossing (ZC), Auto-regression coefficients (ARC), Median frequency (MDF), are extracted as the input of the ANN, and the output of the ANN is the operator's elbow joint angle and the wrist motion. In addition, a 3D upper extremity model, which is built in SolidWorks and then transformed into MATLAB, will imitate the operator's motion simultaneously with the estimations of the ANN. Thus, we accomplish a virtual reality system to realize the real-time simulation and validate the effectiveness of the sEMG-to-motion model. Experiment results show that the system achieves well in model accuracy, hardware compatibility and real time performance with a small mean square error of 1.921 degrees.","Title: High voltage transmission line detection for uav based routing inspection\nYear: 2013\n\nAbstract: The Hough Transform (HT), the Radon Transform (RT) and the Line Segment Detector (LSD) are the most well-known methods for line detection. But the HT and RT methods cost large computing consumption and always resulting a poor performance with many outliers. The LSD method is not effective to the real application of complex background condition. In this paper, a boundary search radon transform (BSRT) approach is proposed for high voltage transmission line detection in Unmanned Aerial Vehicle (UAV) based routing inspection. The core idea assumes that the initial point of an integral line is on one of the four image boundaries, so it isn't always necessary to analyze all points in an image and a new line detection strategy is designed. Comparing to the HT, RT and LSD methods, our method is validated by the experimental results to be fast, efficient and reliable to complex environments.","Title: High gain disturbance observer and its application in robust control attenuation\nYear: 2013\n\nAbstract: High gain observer (HGO) has been proved to be a good method to estimate states of Lipschitz nonlinear systems. In this paper, we focus on the HGO based external input (disturbance) estimator and disturbance attenuation control scheme. Firstly, a robust control scheme is proposed to attenuate the disturbance with the assumption that it is obtainable; subsequently, HGO is designed to estimate both the states and the disturbances, and the convergence is ensured under some conditions; then, it is shown that if the gain of the HGO is selected properly, the BIBO stability of the whole system (nonlinear closed system with observer) can be guaranteed; finally, simulation with respect to an inverted pendulum is carried out and the results verify the validity of the proposed scheme.","Title: Establishing dynamic model for mobile CARM\nYear: 2013\n\nAbstract: Mobile CARM is a more and more important device for spine surgery navigation. The accuracy of the intraoperative image has a huge influence on the surgery success rate. For the purposes to achieve the surgery, the image capture device should be modeled by an accurate method. This paper describes the problems of establishing the CARM model. By analysis the structure of the mobile CARM, we establish the static model of the CARM. Next by kinematics analysis, we establish the dynamic model which could guarantee the accuracy of the CARM. Last we confirm the deviation of CARM images.","Title: Power Line Detection Based On Symmetric Partial Derivative Distribution Prior\nYear: 2013\n\nAbstract: In this paper, we propose a simple but effective image prior-symmetry partial derivative distribution to detect power lines in aerial image for UAVs. The symmetry partial derivative distribution is a kind of statistics of the images. It is based on a key observation-most nature images have symmetry partial derivative distributing. Based on this prior knowledge, we use radon transformation in partial derivative image and recognize the power lines in the aerial image. The experiment results demonstrate our method is effective for automatic power line detection.","Title: A Novel Adaptive Unscented Kalman Filter For Nonlinear Estimation\nYear: 2007\n\nAbstract: The normal unscented Kalman filter (UKF) suffers from performance degradation and even divergence while mismatch between the noise distribution assumed to be known as a priori by UKF and the true ones in a real system. In this paper, a novel adaptive UKF (AUKF) is developed and applied to nonlinear joint estimation of both time-varying states and parameters. A cost function is built based on the error between the covariance matrices of innovation and their corresponding estimations. An adaptive algorithm is then designed to online update the covariance of the process noise by minimizing the cost function. The updated covariance is further fed back into the normal UKF. As a result of using such an adaptive mechanism, the robustness of conventional UKF is substantially improved with respect to the uncertain and time-varying noise covariance in the real system. To illustrate this mechanism, simulations are conducted on the dynamics of an unmanned helicopter by jointly estimating both the states and model errors. The improvements of the proposed AUKF are demonstrated by comparing the results with and without the adaptive mechanism.","Title: An Enhanced Adaptive Set-Membership Filter For Nonlinear Ellipsoidal Estimation\nYear: 2007\n\nAbstract: The extended set-membership filter (ESMF) for nonlinear ellipsoidal estimation suffers from numerical instability, computation complexity, as well as the difficulty in filter parameter selection. In this paper, a UD factorization-based adaptive set-membership filter (AESMF) is developed and applied to nonlinear joint estimation of both time-varying states and parameters. As the result of using the proposed UD factorization, combined with a new sequential and selective measurement update strategy, the numerical stability and real-time applicability of conventional ESMF are substantially improved. Furthermore, an adaptive selection scheme of the filter parameters is derived to reduce the computation complexity and achieve sub-optimal estimation. Simulation results have shown the efficiency and robustness of the proposed method.","Title: Nonlinear model predictive control enhanced by generalized pointwise min-norm scheme\nYear: 2007\n\nAbstract: Nonlinear Model predictive control (NMPC) suffers from the problems of closed loop instability and computation complexity, which greatly limits its application in mechatronic systems involving fast time-varying dynamics. In this paper, a new NMPC enhanced by generalized pointwise min-norm (GPMN) scheme is presented. First, a generalized min-norm control algorithm is developed by introducing a guide function into Freeman's pointwise min-norm control (PMN) algorithm in order to obtain a stable controller based on a known CLF. Then, the guide function is parameterized according to the Bellman's optimization principle and the GPMN scheme is further integrated into normal NMPC strategy. As a result, the closed loop stability of NMPC is guaranteed and the real-time applicability is substantially improved. Simulation results have shown the efficiency of the proposed method.","Title: Yaw Control of Small-scale Helicopter with Time-varying Uncertainty: an Adaptive Robust H2 Control Approach\nYear: 2007\n\nAbstract: This paper is concerned with the robust H2 tracking control problem for the yaw control of a small-scaled helicopter with time-varying uncertainty. The proposed controller incorporates an adaptation mechanism, which improves the performance of system compared with conventional robust controller with a fixed gain. Simulation results of the yaw control of a small-scaled helicopter mounted on an experiment platform have demonstrated the theoretic results.","Title: Milp-Based Trajectory Generation In Relative Velocity Coordinates\nYear: 2007\n\nAbstract: Mixed-integer linear programming (MILP) for trajectory generation of mobile robot suffers from nonlinear constraints due to complex obstacle contours and dynamic environment. In this paper, relative velocity coordinates (RVCs) are proposed for solving the target pursuit and multiple-obstacle avoidance (TPMOA) problem. In the proposed RVCs, nonlinear constraints can be inherently described as linear inequalities, which allow MILP to be utilized to find the optimal trajectory satisfying the linear inequalities. The complexity of obstacle contour does not increase the computational load of the proposed approach. Simulation results are presented in comparison with those of evolutionary algorithm (EA), showing significant improvement in a number of aspects.","Title: Rotorcraft UAV actuator failure estimation with KF-based adaptive UKF algorithm\nYear: 2008\n\nAbstract: A new adaptive Unscented Kalman Filter (UKF) algorithm for actuator failure estimation is proposed. The novel filter method with adaptability to statistical characteristic of noise is presented to improve the estimation accuracy of traditional UKF. The algorithm with the adaptability to statistical characteristic of noise, named Kalman Filter (KF) -based adaptive UKF, is proposed to improve the UKF performance. Such an adaptive mechanism is intended to compensate the lack of a prior knowledge. The asymptotic property of the adaptive UKF is discussed. The Actuator Healthy Coefficients (AHCs) is introduced to denote the actuator failure model while the adaptive UKF is employed for on-line estimation of both the flight states and the AHCs parameters of rotorcraft UAV (RUAV). Simulations are conducted using the model of SIA- Heli-90 RUAV of Shenyang Institute of Automation, CAS. The results are compared with those obtained by normal UKF to demonstrate the effectiveness and improvements of the adaptive UKF algorithm. Besides, we also compare this algorithm with the MIT-based one which we propose in previous research.","Title: LP-based path planning for target pursuit and obstacle avoidance in 3D relative coordinates\nYear: 2010\n\nAbstract: A linear programming (LP) based approach is proposed for the trajectory generation in three dimensional space in which a vehicle is requested to pursue a moving target and avoid static or dynamic obstacles simultaneously. The target pursuit and obstacle avoidance (TPOA) are modeled in relative velocity coordinates, respectively, with linear constraints, according to the LP framework. Two objective functions are defined in terms of relative distance and relative velocity for the optimization. Other constraints, such as those from kinematics, dynamics, and sensor range are fully considered in the proposed method. Simulations are carried out to validate the method.","Title: Knowledge-driven path planning for mobile robots: relative state tree\nYear: 2015\n\nAbstract: Path planning is important in the field of mobile robot. However, traditional path planning techniques optimize the navigation path solely based on the models of the robot and the environments. Owing to the time-varying environment, the robot is expected to launch the replanning procedure in real-time continuously. It is slow and wastes computing resources for repeated decisions. In this study, a new perspective is adopted which utilizes a knowledge-driven approach for path planning. The concept of relative state tree is proposed to develop an incremental learning method based on a path planning knowledge base. The knowledge library, which stores a collection of the mappings from environmental information to robot decisions, can be established by offline or online learnings. As the robot plans online, its movement is guided by the optimal decision that is retrieved from the library based on the information which matches mostly the current environment. A large number of simulations are executed to verify the proposed method. When comparing to $$k$$ k -d tree, this novel method has shown to use smaller storage space and have higher efficiency.","Title: Missing-data Classification with the Extended Full-dimensional Gaussian Mixture Model: Applications to EMG-based Motion Recognition\nYear: 2015\n\nAbstract: Missing data is a common drawback that pattern recognition techniques need to handle when solving reallife classification tasks. This paper first discusses problems in handling high-dimensional samples with missing values by the Gaussian mixture model (GMM). Since fitting the GMM by directly using high-dimensional samples as inputs is difficult due to the convergence and stability issues, a novel method is proposed to build the high-dimensional GMM by extending a reduced-dimensional GMM to the full-dimensional space. Based on the extended full-dimensional GMM, two approaches, namely, marginalization and conditional-mean imputation, are proposed to classify samples with missing-data in online phase. Then, the proposed methods were employed to recognize hand motions from surface electromyography (sEMG) signals, and more than 75% of classification accuracy of motions can be obtained even if 50% of sEMG signals were missing. Comparisons with normal mean and zero imputations also demonstrate the improvements of the proposed methods. Finally, a control scheme for a myoelectric hand was designed by involving the novel methods, and online experiments confirm the ability of the proposed methods to improve the safety and stability of practical systems.","Title: Active Persistent Localization of A 3D Moving Target under Set-Membership Uncertainty Description through Cooperation of Multiple Mobile Robots\nYear: 2015\n\nAbstract: The persistent localization of moving targets is one of the most important applications of mobile robot systems. However, the sensors on each individual robot are often not sufficiently accurate for this task, presenting a severe limitation on the application of robots to many situations. To overcome this problem, systems of multiple robots have been established. These systems improve the localization accuracy of mobile targets by fusing together multiple sensing data. Numerous studies have demonstrated that the relative motion (or specifically, the relative pose) between the robot and the target, as well as that among different robots, strongly influences the final localization accuracy of the data fusion algorithm. In other words, the regulation of motion in a multiple robot system will lead to better localization results. Thus, in this paper, a new active persistent localization (APL) scheme is proposed. The underlying concept of this scheme is based on set-membership descriptions of uncertainties. The basic problem is formulated in the framework of an enhanced set-membership filter, and a new data fusion algorithm with improved accuracy and convergence properties is designed. A motion planning algorithm is then incorporated under the socalled optimal localization condition to complete the APL scheme. Simulations using multiple 3D mobile robot systems and experiments on a multiple rotor-flying-robot testbed show that the proposed algorithm successfully enhances the accuracy of the persistent localization of moving target.","Title: Identification of tissue types and boundaries with a fiber optic force sensor.\nYear: 2014\n\nAbstract: The absence of tactile force information at the tip of a medical instrument makes precise minimally invasive surgery difficult and is prone to resulting in serious outcomes. In this paper, a fiber optic force sensor is fabricated based on Fabry-Perot interferometry and integrated with a puncture needle. The force sensor is attached to the needle tip, where interactive force arises as it inserts into soft tissue. Needle insertion experiments have been conducted on ex vivo swine liver and belly with the calibrated force sensor. Using wavelet transform method, the acquired force data are analyzed and used to identify layered tissue types and boundaries. We found that the force amplitudes are not always identical, but the patterns of forces are almost the same, which enables us to identify layered tissues and to realize a safe needle insertion procedure under robot control.","Title: Coordinative Dynamics Analysis Of A Parallel Manipulator With Three Grippers\nYear: 2014\n\nAbstract: A kinetostatic model and a dynamics model of a parallel manipulator (PM) with three grippers are established and analyzed in the light of its application. First, the coordinative kinematics of this manipulator and three grippers are analyzed. Second, the kinetostatic formulae are derived for transforming the coordinative kinematics and forces applied on the grippers into the workloads applied on the moving platform and the active/constrained forces and torques applied onto active legs. Third, the dynamics formulae are derived for solving dynamic active wrench of grippers and PM by considering inertial mass of the grippers, legs and platform. Finally, a numerical example is given for illustrating application of kinetostatic model and dynamics formulae, and the dynamics solutions of this manipulator are verified by simulation.","Title: Stiffness And Elastic Deformation Of A 3-Leg 5-Dof Parallel Manipulator With One Composite Leg\nYear: 2014\n\nAbstract: The stiffness and elastic deformation of a 3-leg 5-DoF parallel manipulator (PM) with asymmetrical structure and composite active legs are studied systematically. First, a 3-leg 5-DoF 2SPS + PRRPR PM with asymmetrical structure and composite active legs is constructed and its structure constraint characteristics are analyzed. Second, the formulae are derived for solving the elastic deformation and the compliance matrix of the asymmetrical active legs, an asymmetrical stiffness matrix is established for this PM and the elastic deformations of moving platform and legs are solved and analyzed. Finally, a finite element (FE) model of this PM is constructed and the simulation solutions of the elastic deformations of the moving platform are obtained and analyzed. The analytic solutions of the elastic deformations of this PM are verified by its FE simulation solutions.","Title: Simultaneous state and parameter estimation based actuator fault detection and diagnosis for an unmanned helicopter\nYear: 2015\n\nAbstract: AbstractAbstract Simultaneous state and parameter estimation based actuator fault detection and diagnosis FDD for single-rotor unmanned helicopters UHs is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on actuator healthy coefficients AHCs, which are introduced to represent actuator faults, a combined dynamic model is established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for fault tolerant control FTC. Based on the existing widely used nonlinear estimation methods such as the unscented Kalman filter UKF and the extended set-membership filter ESMF, three kinds of adaptive schemes KF-UKF, MIT-UKF and MIT-ESMF are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to unmanned helicopter actuator FDD.","Title: Kernel-Reliability-Based K-Means (Krkm) Clustering Algorithm And Image Processing\nYear: 2014\n\nAbstract: In this paper, we introduced a novel Kernel-Reliability-based K-Means (KRKM) clustering algorithm for categorizing an unknown dataset under noisy condition. Compared with the conventional clustering algorithms, the proposed KRKM algorithm will measure both the reliability and the similarity for classifying data into its neighbor clusters by the dynamic kernel functions, where the noisy data will be rejected by being given low reliability. The reliability for classifying data is measured by a dynamic kernel function whose window size will be determined by the triangular relationship from this data to its two nearest clusters. The similarity from a data item to its neighbor clusters is measured by another adaptive kernel function which takes into account not only the similarity from data to clusters but also that between its two nearest clusters. The main contribution of this work lies in introducing the dynamic kernel functions to evaluate both the reliability and similarity for clustering, which makes the proposed algorithm more efficient in dealing with very strong noisy data. Through various experiments, the efficiency and effectiveness of proposed algorithm have been confirmed.","Title: Quartic Bézier curve based trajectory generation for autonomous vehicles with curvature and velocity constraints\nYear: 2014\n\nAbstract: To generate local trajectory between initial states and target states for autonomous vehicles, a feasible trajectory generation algorithm based on quartic Bézier curve is proposed. The problem of trajectory generation is firstly separated into generating continuous and bounded curvature profile to shape the trajectory and generating linear velocity profile to execute the trajectory. The curvature profile generation is further converted to an optimization problem with only 3 parameters owing to the specific properties of quartic Bézier curve. Sequential quadratic programming is employed to find optimal solution with respect to specific objective function. To avoid sideslip and ensure velocity-continuity and acceleration limits, the framework of linear velocity profile generation is also proposed. A simple profile with constant acceleration is also provided as an example. Simulation results on lane keeping and changing and path following demonstrate the capability and the real-time performance of the proposed algorithm.","Title: A comparative study on PCA and LDA based EMG pattern recognition for anthropomorphic robotic hand\nYear: 2014\n\nAbstract: A multifunctional myoelectric prosthetic hand is a perfect gift for an upper-limb amputee, however, the myoelectric control for a prosthetic hand is not so good now. Here, the paper presents a comparative study on electromyography (EMG) pattern recognition based on PCA and LDA for an anthropomorphic robotic hand. Four channels of surface EMG (sEMG) signals were recorded from the subject's forearm. Time-domain analysis, frequency-domain analysis, wavelet transform analysis, nonlinear entropy analysis and fractal analysis were done and fourteen kinds of features were extracted from sEMG signals. The features were divided into four groups, and the performances of the four groups were compared and analyzed. In the feature projection stage, three schemes were proposed and their performances were compared with each other. The first one only used the principal component analysis (PCA) for dimension reduction. And the second one only used the linear discriminant analysis (LDA) for dimension reduction. The third one used PCA for the first step of dimensionality reduction, and then used LDA for the next step of dimensionality reduction. In the classification stage, minimum distance classifier (MDC) was employed for identifying nine kinds of hand/wrist motions in the projected space. Comparative experiments of four groups of features and three projection schemes were done and evaluated. The online experiment of real-time myoelectric control for an anthropomorphic robotic hand was done as well.","Title: Quasi-LPV modeling and identification for a water-jet propulsion USV: An experimental study\nYear: 2014\n\nAbstract: For an Unmanned Surface Vehicle (USV) system, it is difficult to obtain a precise system model. This is mainly because the USV system is, (1) of extensively complicated and thus presents huge nonlinearities, and (2) easily to be influenced by extensive hydrodynamics. In this paper, our main motivation is to construct a quasi-Linear Parameter Varying (qLPV) dynamical model for a water-jet propulsion USV. The main content of this paper includes two steps: first, theoretical deduction of the qLPV model structure of the USV system is given in detailed including the hydrodynamics; after that, experiments are conducted and the parameter identification results are analyzed to show the priority of the qLPV model compared to some other often referred to models.","Title: Dynamics modeling and performance comparisons of two different rotor flying manipulators: Main-tail-rotor vs eight-rotor\nYear: 2014\n\nAbstract: Rotor flying manipulator (RFM) is a system composed of a rotorcraft and a manipulator. RFM possesses great potential applications and thus has got much concern of the researchers all over the world. However, controller design of the RFM is challenging because of the dynamical coupling between the rotorcraft and the manipulator perplexes the whole system model structure, so the flight performance of the system is more sensitive to some uncertainty factors. Generally, the rotorcraft system of the RFM can be a main-tail-rotor helicopter or multi-rotor aircrafts, which are of completely different flight characteristics. Thus, it is valuable to conduct quantitative coupling analysis of the RFM with different flight platforms. This paper is aimed at this problem. We first construct the dynamics model of the RFM system with respect to different flight platforms, respectively. Then, coupling force and moment are computed quantitatively, and the comparative analysis on the influence of the motion state on them is conducted. Finally, some conclusions are given to show different performances of different kinds of RFM systems.","Title: Two time-scale model based adaptive control for helicopter under unknown wind conditions\nYear: 2014\n\nAbstract: Two time-scale model based adaptive control method is proposed for a helicopter to overcome wind disturbances in this paper. Wind disturbances are considered as a mixture of four sinusoidal signals with unknown frequencies, amplitudes and phases. The controller is designed based on the concept of time-scale separation, which has the advantage of decoupling of the rotational and translational dynamics. Backstepping control and inverse dynamic control method are used to design the fast controller and the slow controller individually and different control intervals are used for the two models. Unscented Kalman filter (UKF) is used for online estimation of wind disturbances. The results from UKF are used for the adaptive reconfiguration of the two time-scaled model based controller. Simulation results show that the adaptive control method reduces the impact of wind disturbances and achieves good performance.","Title: SSVEP based brain-computer interface controlled functional electrical stimulation system for upper extremity rehabilitation\nYear: 2014\n\nAbstract: Brain-computer interface (BCI) is currently developed as an alternative technology with a potential to restore lost motor function in patients with neurological injuries. In this paper, we describe an integrated system of a non-invasive electroencephalogram (EEG)-based BCI with a non-invasive functional electrical stimulation (FES). This system enables the direct brain control of upper limbs to achieve motor rehabilitation. The EEG signals based on steady-state visual evoked potential (SSVEP) were used in the BCI. The classifier of linear discriminant analysis was applied to deal with the frequency domain characteristics and recognize intentions. The identified intentions were transformed into instructions to trigger FES which was controlled with iterative learning control method to stimulate the relevant muscles of upper limbs for motor recovery. Results show that the integration of BCI with an upper-extremity FES is feasible with an average accuracy of about 73.9% over five able-bodied subjects.","Title: Detection of collapsed buildings with the aerial images captured from UAV\nYear: 2016\n\nAbstract: Abstract In this paper, we present a method of detecting the collapsed buildings with the aerial images which are captured by an unmanned aerial vehicle (UAV) for the postseismic evaluation. Different from the conventional methods that apply the satellite images or the high-altitude UAV for the coarse disaster evaluation over large area, the purpose of this work is to achieve the accurate detection of collapsed buildings in small area from low altitude. By combining the motion and appearance features of collapsed buildings extracted from successive aerial images, each pixel in the input image will be measured by a statistical method where the background pixels will be penalized and the ones of collapsed buildings will be assigned with high value. The candidates of collapsed buildings will be established by integrating the extracted feature points into local groups with the online clustering algorithm. To reduce the false alarm caused by the complex background noise, each predicted candidate will be further verified by the temporal tracking framework where both the trajectory and the appearance of a candidate will be measured. The candidate of collapsed buildings that can survive through long time will be considered as true positive, otherwise rejected as a false alarm. Through extensive experiments, the efficiency and the effectiveness of proposed algorithm have been proved.","Title: sEMG based quantitative assessment of acupuncture on Bell’s palsy: an experimental study\nYear: 2015\n\nAbstract: Acupuncture is a traditional Chinese therapeutic method, recognized by western medicine as an important complementary therapy. However, the efficacy assessment of this traditional intervention has been mainly empirical rather than scientific. In this paper, we propose a surface electromyography (sEMG) based approach for quantitative assessment of acupuncture on Bell’s palsy. The assessment is made by comparing the muscle activities of healthy with diseased ones. A feature-vector of four individual sEMG features is introduced for more comprehensive representation of muscle activity. A clustering technique is then proposed to calculate quantitative differences between the muscle activities of the healthy and diseased sides. A regressive model is also proposed to predict the recovery trend of a patient based on the quantitative assessments during his/her clinical acupuncture history. As reported in the paper, a total of 20 selected Bell’s palsy patients have participated in the extensive experiments that were conducted to verify the performance of the proposed method.","Title: Digital Comparator In Excitable Chemical Media\nYear: 2015\n\nAbstract: It is well established that spatial excitable media can be used for information processing. A single excitation pulse can represent one bit of information and a group of excitations forms a message. Different structures designed can realize different functions of infonnation processing. In this paper, we systematically designed structures of digital comparator, and numerical simulations have been carried out to show that these structures can realize the function of digital comparator well. Firstly we designed one-bit and two-bit digital comparator, and then we successfully designed three-bit digital comparator in two different ways, thus we demonstrated two expanding ways to realize the multi-bit digital comparator: nesting way and cascading way. We believe that the realization of digital comparator is helpful for the constructions of other logic and arithmetic functions, and ultimately can bring great potential applications for the implementation of chemical computer and other intelligent systems.","Title: Wave-Based Tracking Control of a Flexible Arm Using Lumped Model.\nYear: 2014\n\nAbstract: A wave control is presented to suppress vibration at the distal end of a flexible robotic arm while achieving accurate tracking control. It assumes the arm with an actuator at one end and a load at the other, and interprets the arm's dynamics with a lumped model in terms of mechanical waves entering and leaving the arm at the actuator-arm interface. Control input to the actuator is then resolved into two superposed waves, which the actuator launches and absorbs simultaneously. From the motion start-up, the launch wave is assigned to the actuator, to which the absorbing wave is added. The absorbing wave is computed with the delayed tip motion. It absorbs the vibratory energy within the arm, and prevents the wave returning from the arm tip from entering the control system again. The control system's properties are investigated, and it works pretty well for trajectory tracking control, as demonstrated in the numerical results.","Title: Assessment of the Effectiveness of Acupuncture on Facial Paralysis Based on sEMG Decomposition.\nYear: 2014\n\nAbstract: Although acupuncture has been extensively and routinely applied in clinic around the world, its use is conventionally based on empirical knowledge rather than scientific evidence. In this paper, we investigate the surface electromyographic (sEMG) activity on the face of patients with facial paralysis to validate the effectiveness of acupuncture. sEMG decomposition method is employed to quantify of the differences between the healthy and diseased sides, which includes 2 parts: to decompose sEMG into motor units action potential trains (MUAPTs) with Gaussian Mixture Model (GMM); to assess the recovery of patients with facial paralysis according to the differences between the MUAPTs of healthy and diseased sides. Finally, an auto-regression model is used to predict the recovery trends. Results indicate that the proposed method can assess the effectiveness of acupuncture on facial paralysis and achieve a high accuracy of 90.94% to predict the recovery trends.","Title: Shape Reconstruction And Attitude Estimation Of Bevel-Tip Needle Via Ct-Guidance\nYear: 2015\n\nAbstract: The bevel-tip flexible needle is an improvement of the traditional rigid needle and has the potential to reduce traumas, improve the controllability and reach multi-targets in one insertion. The needle steering robot system has the ability to deal with complex puncture environment and to improve the puncture precision, but it requires a precise feedback of needle tip's position and attitude. Computerized tomography (CT) is a widely available imaging system that provides precise and clear images. Unfortunately, CT is not a real-time system and it is impossible to fetch the attitude of bevel-tip needle from CT image. A new method is proposed to estimate the attitude, in which the unscented kalman filter is employed. We extract the positions of the needle in CT images, reconstruct the needle shape, calculate the control quantity according to the insert distance and then estimate the attitude of the needle tip. Simulations and experiments demonstrate that the method proposed is effective. Implementation of shape reconstruction and attitude estimation of the bevel-tip needle in biological tissue is a significant step toward the precise control of bevel-tip needles.","Title: Invariant-Set-Based Planning Approach For Obstacle Avoidance Under Vehicle Dynamic Constraints\nYear: 2015\n\nAbstract: Autonomous vehicles require the ability to safely operate under both external environment constraints such as obstacles, and their own limits such as dynamic conditions. The problem of planning feasible control reference inputs against both constraints is still an open question. In this paper, the contribution is to propose an Invariant-Set-Based Planning (ISBP) approach which can move a vehicle from an initial point to a goal point by calculating feasible control reference inputs with satisfying both constraints simultaneously. A series of invariant sets will be calculated to cover feasible path and system input constraints will be novelly modified to calculate each invariant set. Finally, ISBP approach will be achieved by solving a set of linear matrix inequalities (LMIs).","Title: Input-Output Response Based Simultaneous Tracking And Disturbance Attenuation Control For Helicopter Image Stabilizers\nYear: 2015\n\nAbstract: Image stabilizer is important for most unmanned helicopter system. Usually it should be able to drive the video sensor to track some targets precisely under heavy vibration due to the high speed rotation of the rotor. This is the so-called simultaneous tracking and disturbance attenuation control (STDA) problem. In this paper, a new 2DOF control strategy is proposed aiming at the STDA problem. The proposed control is composed of inner loop control, which is used to attenuate the disturbance due to helicopter's vibration, and a prefilter, which is outside the closed loop and used to ensure the transient performance of the whole system. One of the most absorbing advantages of the new proposed method is that the two parts are decoupled completely and thus can be designed separately. For inner loop control, an AFC enhanced PID control is proposed to realize disturbance suppression, while for the prefilter, a new parameter optimization algorithm is introduced to ensure optimal step tracking without influencing the disturbance attenuation performance. Furthermore, it should be pointed out that the whole controller is designed based on only input-output response independent on accurate model information of the system. Finally, experiments are conducted on a real image stabilizer with simulated vibration, and the results show the feasibility and validity of the proposed method.","Title: Multi-Relation Octomap Based Heuristic Icp For Air/Surface Robots Cooperation\nYear: 2015\n\nAbstract: In this paper, we focus on the problem of fast and accurate featureless registration of outdoor large scale 3D point-clouds which possess great differences in the aspects of both resolution and view of point. There are two main methods generally used to solve this problem: feature based algorithm and point based one. However, feature based method can only be used in very special environments with clear geometric structure, while traditional point based method can only obtain a relative coarse estimation and is sensitive to initial alignment. Thus, in this paper, a registration algorithm, called Octree Based Multiresolution Heuristic ICP, is proposed.Without relying on the good initial registration and marked features, hybrid-ICP combines different ICP algorithms, and improve the alignments using finer levels of representation.In our outdoor riverside environments experiments, our method outperform the classical point based registration algorithm with an accuracy of 7 times better than classical Generalized-ICP and a speedup 1.6 times.","Title: Real-Time Data Acquisition and Model Identification for Powered Parafoil UAV.\nYear: 2015\n\nAbstract: Powered Parafoil UAV PPUAV is a kind of different aircraft from common UAVs. It consists of parafoil canopy, payload and suspension lines and has the adventages of simple structure, low cost and high load weigh ratio, which is suitable for large-area and long-time surveillance and airdrop missions. This type of UAV has the problems of adding mass and flexible connection, and it is not easy to build the accurate model, which brings challenges to theoretical study and practical applications. This paper designs the structure of PPUAV and real-time data acquisition system, obtains flight data for modeling, identifies and validates the transfer functions using Matlab System Identification Toolbox. Finally the model of PPUAV is obtained, which gives a practicable method of PPUAV modeling and does a preliminary work for the following controller design and mission planning.","Title: SSVEP-Based Brain-Computer Interface Controlled Functional Electrical Stimulation System for Upper Extremity Rehabilitation.\nYear: 2016\n\nAbstract: Traditional rehabilitation techniques have limited effects on the recovery of patients with tetraplegia. A brain–computer interface (BCI) provides an interactive channel that does not depend on the normal output of peripheral nerves and muscles. In this paper, an integrated framework of a noninvasive electroencephalogram (EEG)-based BCI with a noninvasive functional electrical stimulation (FES) is established, which can potentially enable the upper limbs to achieve more effective motor rehabilitation. The EEG signals based on steady-state visual evoked potential are used in the BCI. Their frequency domain characteristics identified by the pattern recognition method are utilized to recognize intentions of five subjects with average accuracy of 73.9%. Furthermore the movement intentions are transformed into instructions to trigger FES, which is controlled with iterative learning control method, to stimulate the relevant muscles of upper limbs tracking desired velocity and position. It is a useful technology with potential to restore, reinforce or replace lost motor function of patients with neurological injuries. Experiments with five healthy subjects demonstrate the feasibility of BCI integrated with upper extremity FES toward improved function restoration for an individual with upper limb disabilities, especially for patients with tetraplegia.","Title: Enhanced ICP for the Registration of Large-Scale 3D Environment Models: An Experimental Study.\nYear: 2016\n\nAbstract: One of the main applications of mobile robots is the large-scale perception of the outdoor environment. One of the main challenges of this application is fusing environmental data obtained by multiple robots, especially heterogeneous robots. This paper proposes an enhanced iterative closest point (ICP) method for the fast and accurate registration of 3D environmental models. First, a hierarchical searching scheme is combined with the octree-based ICP algorithm. Second, an early-warning mechanism is used to perceive the local minimum problem. Third, a heuristic escape scheme based on sampled potential transformation vectors is used to avoid local minima and achieve optimal registration. Experiments involving one unmanned aerial vehicle and one unmanned surface vehicle were conducted to verify the proposed technique. The experimental results were compared with those of normal ICP registration algorithms to demonstrate the superior performance of the proposed method.","Title: Active Model-Based Control for Pneumatic Artificial Muscle.\nYear: 2017\n\nAbstract: In this paper, an active model-based control scheme is developed for the pneumatic artificial muscle (PAM), to compensate for the uncertainties in the dynamics model of the PAM. First, a simplified three-element model with respect to a specific range of pressure is formulated as the reference model. Second, a Kalman filter is adopted to actively estimate the errors involved in the reference model,...","Title: Self-Healing Control Design under Actuator Fault Occurrence on Single-rotor Unmanned Helicopters.\nYear: 2016\n\nAbstract: Actuator faults are inevitable but affect reliability and safety of unmanned helicopters (UHs), especially when there are actuator constraints. In this paper, self-healing control, which is an extended active fault-tolerant control (FTC) method with reference redesign on-line, is proposed to analyze and to guarantee the safety of single-rotor UHs (SUHs) under both actuator faults and constraints. The safety includes body safety and mission safety. More specifically, body safety represents the stability of SUH itself and mission safety represents mission accomplishment with acceptable performance, furthermore, set-point tracking mission is considered. The main contribution of this paper is to analyze and to guarantee the safety of SUHs by solving a set of Linear Matrix Inequalities (LMIs) at one time. The set of LMIs includes saturation compensator design and stability guaranty with a given controller in the absence of actuator constraints, actuator fault compensation analysis, reference reachability analysis and reference redesign. On the other hand, by adding swashplate configuration, SUH model with real actuator outputs as control inputs is constructed which can describe actuator faults more clearly compared to SUH models with nominal control inputs. Finally, the proposed self-healing control method is illustrated by simulation with a nonlinear SUH model.","Title: Design and Analysis of a Mutual Inductance Coupling-Based Microdeformation Sensor.\nYear: 2017\n\nAbstract: Mutual inductance coupling-based electromagnetic sensors utilize the quasi-static or dynamic magnetic excitation and sensing signals to detect the multiaxis deformation. The compact size and high sensitivity allow their application in tiny and precise measurement systems, such as space-confined minimally invasive surgery. Until now, however, there has not been any theoretical derivation of the rel...","Title: Nonlinear Modeling for a Water-Jet Propulsion USV: An Experimental Study.\nYear: 2017\n\nAbstract: Although unmanned surface vehicles (USVs) have been extensively researched and applied to many typical scenarios, high-performance autonomous control is still an open problem. One of their major problem stems from the difficulty in constructing a sufficient accurate and sufficient simple control-oriented dynamics model. Owing to the highly complicated physical mechanisms of hydrodynamics, USV syst...","Title: Gpu-Based Heuristic Escape For Outdoo Large Scale Registration\nYear: 2016\n\nAbstract: heterogeneous robot introduce a higher perception ability than single type robots in outdoor environments. One key problem is to making the 3D environmental model from the cooperated robots in real time, especially in the unstructured environment. Based on our previous work on outdoor environment registration method, in this paper, we introduce a CPU based Enhanced ICP method for large-scale heterogeneous robot registration. First, we combine the GPU-based nearest neighbor search in the traditional ICP framework. Second, we proposed a measurement and estimation model for the local minima problem. Third, we proposed a CPU-based heuristic escape method to generate the escaping transformation in real time. Experiments involving one unmanned aerial vehicle and one unmanned surface vehicle were conducted to verify the proposed technique. The experimental results were compared with those of normal ICP registration algorithms to demonstrate the performance of the proposed method.","Title: Robust Tracking Of Dexterous Continuum Robots: Fusing Fbg Shape Sensing And Stereo Vision\nYear: 2017\n\nAbstract: Robust and efficient tracking of continuum robots is important for improving patient safety during space-confined minimally invasive surgery, however, it has been a particularly challenging task for researchers. In this paper, we present a novel tracking scheme by fusing fiber Bragg grating (FBG) shape sensing and stereo vision to estimate the position of continuum robots. Previous visual tracking easily suffers from the lack of robustness and leads to failure, while the FBG shape sensor can only reconstruct the local shape with integral cumulative error. The proposed fusion is anticipated to compensate for their shortcomings and improve the tracking accuracy. To verify its effectiveness, the robots' centerline is recognized by morphology operation and reconstructed by stereo matching algorithm. The shape obtained by FBG sensor is transformed into distal tip position with respect to the camera coordinate system through previously calibrated registration matrices. An experimental platform was set up and repeated tracking experiments were carried out. The accuracy estimated by averaging the absolute positioning errors between shape sensing and stereo vision is 0.67 +/- 0.65 mm, 0.41 +/- 0.25 mm, 0.72 +/- 0.43 mm for x, y and z, respectively. Results indicate that the proposed fusion is feasible and can be used for closed-loop control of continuum robots.","Title: A Novel Real-Time Gesture Recognition Algorithm For Human-Robot Interaction On The Uav\nYear: 2017\n\nAbstract: This paper provides a new real-time gesture recognition technology for Unmanned Aerial Vehicle (UAV) Control. Despite of the tradition robot controlling system that uses the pre-defined program to control the UAV, this system allows the users to on-line design and control the UAV to finish the abrupt urgent task with different gestures. The system is composed of three parts: On-line personal feature training system, Gesture recognition system and UAV motion control system. In the first part, we collect and analyze user gestures, extract features data and train the recognition program in real time. In the second part, a multi-feature hierarchical filtering algorithm is applied to guarantee both the accuracy and real-time processing speed of our gesture recognition method. In the last part, the gesture recognition result is translated to a UAV through a data transmitter based on Mavlink protocol to achieve the human on-line control for the UAV. Through two extensive experiments, the effectiveness and efficiency of our method has been confirmed.","Title: Artificial compound eye: a survey of the state-of-the-art.\nYear: 2017\n\nAbstract: An artificial compound eye system is the bionic system of natural compound eyes with much wider field-of-view, better capacity to detect moving objects and higher sensitivity to light intensity than ordinary single-aperture eyes. In recent years, renewed attention has been paid to the artificial compound eyes, due to their better characteristics inheriting from insect compound eyes than ordinary optical imaging systems. This paper provides a comprehensive survey of the state-of-the-art work on artificial compound eyes. This review starts from natural compound eyes to artificial compound eyes including their system design, theoretical development and applications. The survey of artificial compound eyes is developed in terms of two main types: planar and curved artificial compound eyes. Finally, the most promising future research developments are highlighted.","Title: Condition directed Multi-domain Adversarial Learning for Loop Closure Detection.\nYear: 2017\n\nAbstract: Loop closure detection (LCD) is the key module in appearance based simultaneously localization and mapping (SLAM). However, in the real life, the appearance of visual inputs are usually affected by the illumination changes and texture changes under different weather conditions. Traditional methods in LCD usually rely on handcraft features, however, such methods are unable to capture the common descriptions under different weather conditions, such as rainy, foggy and sunny. Furthermore, traditional handcraft features could not capture the highly level understanding for the local scenes. In this paper, we proposed a novel condition directed multi-domain adversarial learning method, where we use the weather condition as the direction for feature inference. Based on the generative adversarial networks (GANs) and a classification networks, the proposed method could extract the high-level weather-invariant features directly from the raw data. The only labels required here are the weather condition of each visual input. Experiments are conducted in the GTAV game simulator, which could generated lifelike outdoor scenes under different weather conditions. The performance of LCD results shows that our method outperforms the state-of-arts significantly.","Title: Towards Stable Adversarial Feature Learning for LiDAR based Loop Closure Detection.\nYear: 2017\n\nAbstract: Stable feature extraction is the key for the Loop closure detection (LCD) task in the simultaneously localization and mapping (SLAM) framework. In our paper, the feature extraction is operated by using a generative adversarial networks (GANs) based unsupervised learning. GANs are powerful generative models, however, GANs based adversarial learning suffers from training instability. We find that the data-code joint distribution in the adversarial learning is a more complex manifold than in the original GANs. And the loss function that drive the attractive force between synthesis and target distributions is unable for efficient latent code learning for LCD task. To relieve this problem, we combines the original adversarial learning with an inner cycle restriction module and a side updating module. To our best knowledge, we are the first to extract the adversarial features from the light detection and ranging (LiDAR) based inputs, which is invariant to the changes caused by illumination and appearance as in the visual inputs. We use the KITTI odometry datasets to investigate the performance of our method. The extensive experiments results shows that, with the same LiDAR projection maps, the proposed features are more stable in training, and could significantly improve the robustness on viewpoints differences than other state-of-art methods.","Title: An active fault-tolerant control framework against actuator stuck failures under input saturations\nYear: 2017\n\nAbstract: AbstractAbstract In this paper, a control framework including active fault-tolerant control FTC and reference redesign is developed subject to actuator stuck failures under input saturations. FTC synthesis and reference redesign approaches are proposed to guarantee post-fault system safety and reference reachability. Then, these features are analyzed under both actuator stuck failures and constraints before fault-tolerant controller switches. As the main contribution, actuator stuck failures and constraints are unified so that they can be easily considered simultaneously. By means of transforming stuck failures into actuator constraints, the post-fault system can be regarded as an equivalent system with only asymmetrical actuator constraints. Thus, methods against actuator saturations can be used to guarantee regional stability and produce the stability region. Based on this region, stuck compensation is analyzed. Specifically, an unstable open-loop system is considered, which is more challenging. Furthermore, the method is extended to a set-point tracking problem where the reachability of the original reference can be evaluated. Then, a new optimal reference will be computed for the post-fault system if the original one is unreachable. Finally, simulation examples are shown to illustrate the theoretical results.","Title: Synchronous Adversarial Feature Learning for LiDAR based Loop Closure Detection\nYear: 2018\n\nAbstract: Loop C losure Detection (LCD) is the essential module in the simultaneous localization and mapping (SLAM) task. In the current appearance-based SLAM methods, the visual inputs are usually affected by illumination, appearance and viewpoints changes. Comparing to the visual inputs, with the active property, light detection and ranging (LiDAR) based point-cloud inputs are invariant to the illumination and appearance changes. In this paper, we extract 3D voxel maps and 2D top view maps from LiDAR inputs, and the former could capture the local geometry into a simplified 3D voxel format, the later could capture the local road structure into a 2D image format. However, the most challenge problem is to obtain efficient features from 3D and 2D maps to against the viewpoints difference. In this paper, we proposed a synchronous adversarial feature learning method for the LCD task, which could learn the higher level abstract features from different domains without any label data. To the best of our knowledge, this work is the first to extract multi-domain adversarial features for the LCD task in real time. To investigate the performance, we test the proposed method on the KITTI odometry dataset. The extensive experiments results show that, the proposed method could largely improve LCD accuracy even under huge viewpoints differences.","Title: Vibration Control of a Flexible Robotic Arm by Wave Absorption Based on a Lumped Dynamic Model.\nYear: 2016\n\nAbstract: A wave absorption control strategy is proposed to suppress vibration at the distal end of a flexible robotic arm while achieving accurate position control. It assumes the flexible arm with an actuator at one end and a load at the other, and interprets the arm's dynamics with a lumped model in terms of mechanical waves entering and leaving the arm at the actuator-arm interface. Control input to the actuator is thus resolved into two superposed waves, which the actuator launches and absorbs simultaneously. From the motion start-up, the launch wave is assigned to the actuator, to which the absorbing wave is added subsequently. The absorbing wave is computed with the delayed tip motion. It absorbs the vibratory energy within the arm, and prevents the wave returning from the arm tip from entering the control system again. The properties of the control scheme proposed are studied throughout. It works very well under uncertainty, and is stable and robust, for tip positioning and trajectory tracking control, as demonstrated in the numerical results.","Title: An inter-subject model to reduce the calibration time for motion imagination-based brain-computer interface.\nYear: 2019\n\nAbstract: A major factor blocking the practical application of brain-computer interfaces (BCI) is the long calibration time. To obtain enough training trials, participants must spend a long time in the calibration stage. In this paper, we propose a new framework to reduce the calibration time through knowledge transferred from the electroencephalogram (EEG) of other subjects. We trained the motor recognition model for the target subject using both the target's EEG signal and the EEG signals of other subjects. To reduce the individual variation of different datasets, we proposed two data mapping methods. These two methods separately diminished the variation caused by dissimilarities in the brain activation region and the strength of the brain activation in different subjects. After these data mapping stages, we adopted an ensemble method to aggregate the EEG signals from all subjects into a final model. We compared our method with other methods that reduce the calibration time. The results showed that our method achieves a satisfactory recognition accuracy using very few training trials (32 samples). Compared with existing methods using few training trials, our method achieved much greater accuracy. Graphical abstract The framework of the proposed method. The workflow of the framework have three steps: 1, process each subjects EEG signals according to the target subject's EEG signal. 2, generate models from each subjects' processed signals. 3, ensemble these models to a final model, the final model is a model for the target subject.","Title: Contact Force Control Of An Aerial Manipulator In Pressing An Emergency Switch Process\nYear: 2018\n\nAbstract: The dangerous work situation in industrial leakage accidents urgently needs a flexible and small robot to help workers perform operations and to protect them from being injured. An aerial manipulator system consisting of a hexa-rotor UAV and a one-DOF manipulator is developed, and is used to press an emergency switch to shut off machinery in an emergency. In practical application, an aerial manipulator usually performs contact operations as the UAV platform is in hover flight. The hovering UAV acting as a spring-mass-damper system is firstly proved. Then, based on the derived spring-mass-damper system model and the impedance control algorithm, the force-sensorless contact force control method is presented. That is, the force is indirectly controlled through controlling the UAV's position error and pitch angle simultaneously. The practical operation experiment of pressing an emergency button shows that the proposed method is able to control the contact force as the aerial manipulator interacts with the external environment.","Title: Path-tracking control of bevel-tip needles using Model Predictive Control\nYear: 2016\n\nAbstract: The bevel-tip flexible needle is an improvement of the clinical puncture needle and has the potential to reduce surgery traumas and improve puncture accuracy. Due to the nonholonomic kinematics model, it is difficult to drive flexible needles to track a pre-plan path. In this paper, we propose an effective path tracking control method based on Model Predictive Control (MPC). The kinematics model of flexible needles is described firstly, according to which the control method is designed. Then, the path tracking control method is presented in detail. The finite prediction horizon of MPC is extended to infinite in order to obtain a global optimal solution. Due to the nonlinear model, the objective function of receding horizon optimization is also nonlinear, and Particle Swarm Optimization (PSO) is employed to search optimal predictive control series. At last, simulations are conducted and results illustrate that the proposed controller performs well to precisely drive the flexible needle to track a desired path.","Title: Separated adaptive control scheme of a rotor-flying manipulator\nYear: 2016\n\nAbstract: Rotor flying manipulator (RFM), a new kind of mobile robot system being composed of a rotor flying robot (RFR) and a (several) manipulator(s), has absorbed great attentions in recent years because it enables a RFR to complete active tasks such as mastering and transporting objects. However, steady control of the RFM during both maneuvering and operating is of great difficulty due to the heavy force/moment coupling between the RFR and the manipulator, which introduce high nonlinearity and complexity to the system model. In this paper, a new control scheme of the RFM is proposed to ensure the steady flight. Firstly, the nonlinear mathematical model is derived, which is followed by the coupling analysis to show how the movement of the manipulator influences the whole system's behavior. Subsequently, based on these analyses, a new control scheme is designed with obtainable coupling force/moment. The basic idea of the controller is to take the coupling as a disturbance and separately control the RFR and the manipulator, and the stability is ensured to properly design the controller parameters. Finally, simulations are conducted and the results show the feasibility and validity of the proposed controller.","Title: Natural Growth-Inspired Distributed Self-Reconfiguration of UBot Robots.\nYear: 2019\n\nAbstract: The decentralized self-reconfiguration of modular robots has been a challenging problem. This work proposed a biological method inspired by the plant growth for the distributed self-reconfiguration of UBot systems. L-systems are implemented to construct target topology, and turtle interpretation is extended to lead the self-reconfiguration process. Parametric reproduction rules introduce the external influence to the reconfiguration process by distributed modules' local sensing. Each module can move independently to change relative positions, and robotic structures develop in the natural growth style. This leads to a convergent and environmentally sensitive control method for the distributed self-reconfiguration. Reconfiguration processes can converge to desired configuration and are scalable to module numbers by reproducing predefined substructures in principle. The overall performance of the proposed strategy is evaluated with simulations and 11 experiments. Simulation and experimental results turn out to be convergent and environmentally sensitive.","Title: Active modeling for pneumatic artificial muscle\nYear: 2016\n\nAbstract: In this paper, an active modeling approach for a pneumatic artificial muscle (PAM) is being considered. The PAM's nonlinearity, hysteresis and time-varying characteristics cause difficulties in modeling its behavior and designing high-performance controllers. Here, a generalized three-element model of a PAM is proposed to obtain the reference model in the reference mode (in a given small pressure range). The equivalent state space representation of the reference model is obtained by applying the linearization approach. The model error is introduced to the equivalent state space model, and the joint estimation is adopted to estimate the system state and the model error simultaneously. Experimental studies are conducted to demonstrate the existence of the model error, and verify the necessity of introducing the model error to the reference model, and evaluate the effect of the proposed active modeling approach in changing modes (not in the given pressure range).","Title: Mechanical Design And Control Method Of A Hollow Modular Joint For Minimally Invasive Spinal Surgery\nYear: 2018\n\nAbstract: Design of the hollow modular joint plays an important role in modern robot layout, fixation, and wiring. In this paper, a hollow modular joint that meets the requirement of a minimally invasive surgical robot is proposed. The mechanical and control design is sequentially illustrated, and the torque sensor and its optimization are provided. Furthermore, a free-force control method is introduced. To analyze the designed module, the simulation of the redundant robot, comprised of the designed joint in seven degrees of freedom, is presented. The results of analyses showed that the designed hollow modular joint is valid and effective.","Title: Closed-loop control of bevel-tip needles based on path planning.\nYear: 2018\n\nAbstract: Bevel-tip needles have the potential to improve paracentetic precision and decrease paracentetic traumas. In order to drive bevel-tip needles precisely with the constrains of path length and path dangerousness, we propose a closed-loop control method that only requires the position of the needle tip and can be easily applied in a clinical setting. The control method is based on the path planning method proposed in this paper. To establish the closed-loop control method, a kinematic model of bevel-tip needles is first presented, and the relationship between the puncture path and controlled variables is established. Second, we transform the path planning method into a multi-objective optimization problem, which takes the path error, path length and path dangerousness into account. Multi-objective particle swarm optimization is employed to solve the optimization problem. Then, a control method based on path planning is presented. The current needle tip attitude is essential to plan an insertion path. We analyze two methods to obtain the tip attitude and compare their effects using both simulations and experiments. In the end, simulations and experiments in phantom tissue are executed and analyzed, the results show that our methods have high accuracy and have the ability to deal with the model parameter uncertainty.","Title: Kf-Based Active Modeling For A Quadrotor Slung Load System\nYear: 2018\n\nAbstract: The control of quadrotor slung load (QSL) systems is a challenging task as a result of some distinguishing features like the multiple nonlinearities and time-varying load swing. To design an effective control scheme, the top priority is to establish an excellent model. In this paper, a practical active modeling method based on the Kalman Filter (KF) for a QSL system is developed to compensate uncertainties in system dynamics. First, a simplified quadrotor model is formulated as the reference model. Second, modeling errors are introduced and the KF is adopted to actively estimate the errors involved in the reference model. Finally, some experiments are conducted to validate the remarkable performance of the proposed modeling strategy in terms of uncertainties as well as disturbances in the dynamic model.","Title: Force Feedback Control of a Robotic Needle Insertion into Layered Soft Tissues\nYear: 2018\n\nAbstract: In this study, a feedback control law is proposed to steer a robotic needle using force information from a fiber optic sensor. This sensor is integrated into the lumen at the distal end of the needle to measure the needle insertion force. The force signals are analyzed via wavelet transform to identify the boundaries of layered soft tissues in real time. The boundaries information is then used in the robotic needle steering scheme to reduce as much as possible the insertion force, and mitigate the risk of tissue injury. Porcine belly tissue phantoms are herein used in the ex vivo tests of robotic needle insertion, and comparative study has been done with and without insertion force feedback. Experimental results show that the force feedback control approach proposed reduces effectively the insertion force.","Title: Path Planning of UGV Based on Bézier Curves\nYear: 2019\n\nAbstract: An effective path planner is critical for autonomous traversal of unmanned ground vehicles (UGVs) in harsh environments. This paper describes a novel path planning method considering Bezier curves and a two-layer planning framework. In the two-layer framework, a road centerline (RCL) estimator located on the upper layer works as a global planner to obtain the local target for the bottom local planner. The RCL is estimated from a series of candidate Bezier curves based on a safety criterion. In the bottom layer, an optimal trajectory planner and a speed planner make up the local planner to obtain the desired steering turning angle and linear speed. The criteria for optimal trajectory selection are designed for comfortable driving. Road safety is considered in the speed planner for robust driving. Three sets of simulations are used to evaluate and quantify the relative performance of variations of our path planning algorithm. The proposed path planning method is implemented on a modified Polaris RZR 800 UGV, too. Two experiments based on this UGV are set up in the country road environment to demonstrate the viability of the proposed method.","Title: A novel ESMF-based observer and control scheme for a type of tendon-sheath hysteresis system\nYear: 2021\n\nAbstract: Due to the backlash hysteresis, robust and accurate tracking control of a hysteresis system is a challenging problem. We propose in this paper an active observer based robust control scheme to reject the influence of hysteresis. Firstly, the normal piecewise C–H model of hysteresis plant was modified into a continuous form so that an active observer could be applied on. Secondly, an observer was designed based on the extended set-membership filter (ESMF). This intends to take the advantages of ESMF on the bound-guaranteed estimation and the unknown but bounded (UBB) noise tolerance. Thirdly, a robust controller was constructed using both the magnitude and the bounds of the hysteresis uncertainty estimated by the observer. The stability of the control scheme was theoretically proved. Experiments were conducted on a robotic flexible ureteroscope test-bed. The performance of the modified model, the ESMF-based observer, and the robust control were extensively verified, and the improvements benefited from this proposed scheme were demonstrated.","Title: A BAS-Based Strategy for Redundant Manipulator Tracking Continuous Moving Object in 3D Relative Velocity Coordinate\nYear: 2021\n\nAbstract: The ability of real-time tracking of manipulator end-effect is critical for intelligent manipulators. This paper presents a control strategy for tracking the continuous moving object. Our research aims at converting the problem of tracking moving object to a planning problem of relative velocity vector by establishing Relative Velocity Coordinate (RVC) on manipulator end-effect. The key novelty of the proposed strategy about constructing the optimization problem lies in considering both relative velocity and relative position simultaneously. The Beetle Antennae Search (BAS) algorithm is introduced to tackle the formulated optimization function. Theory analysis and different simulation experiments are provided to illustrate the feasibility and efficiency of the proposed control strategy.","Title: Design and Development of a Portable Electrical Impedance Tomography System\nYear: 2021\n\nAbstract: Electrical impedance tomography (EIT) is a non-invasive detection technique for human tissue imaging. However, most of the current EIT systems are complex and expensive in design. In this paper, we have developed a portable and economic EIT system, which just consists of five parts, including a data acquisition card (DAQ), a power module, a signal generator, a voltage-controlled current source, and a multiplexer module. The fast Fourier transform is used to extract the amplitude of the voltage signals collected by the DAQ. The Tikhonov regularization algorithm is adopted to reconstruct the image of conductivity distribution. Experiments on a practical phantom were designed and conducted to validate the performance of the system. The results showed that the developed system has an average signal-to-noise ratio of 65 dB for measurement channels and a high imaging signal accuracy of 0.99. The conductivity distribution in the phantom was successfully reconstructed by the developed EIT system.","Title: Continuous Estimation of Knee Angles from Decomposition of Single Channel Surface Electromyography Signals\nYear: 2021\n\nAbstract: Multiple surface electromyography (sEMG) channels used in motion estimation would increase implementation complexity. However, reduced sEMG channels would lead to insufficient information and deteriorate the estimation performance. This paper studies the problem of motion estimation based on single-channel sEMG signals by combining a decomposition method into a state-space model. More precisely, t...","Title: Active Modeling and Control for Manipulators\nYear: 2021\n\nAbstract: In this paper, an active model-based control scheme is proposed for the manipulators with parameter uncertainties and disturbances. Firstly the Euler-Lagrange dynamic model of n-link manipulator is linearized by Lie derivation. Then Kalman Filter is utilized to estimate the model error in real-time. Moreover, an active model enhanced state feedback controller is proposed based on the estimated mod...","Title: Modeling and Robust Adaptive Control for Tendon-Driven with Bending Tip Systems\nYear: 2021\n\nAbstract: Tendon-driven with bending tip (TDBT) mechanisms were extensively applied in the field of surgery and rescue robotics. TDBT has exposed many complicated characteristics, such as complex hysteresis, motion backlash and rate-dependent behavior, etc., which bring great challenges to the modeling and control subject of the bending angle. In this research, the TDBT's dynamics model was established with...","Title: Preliminary Design and Performance Test of an Origami Actuator Inspired by Yoshimura Pattern\nYear: 2021\n\nAbstract: Origami has been inspiring roboticists to create new devices. Here, we present a preliminary design and performance test of a novel origami actuator inspired by Yoshimura pattern. This actuator is in a hexagonal configuration made of a single piece of paper. Driven by the threads, the origami actuator can bend and shorten. The design of its folding pattern is presented, and the folding procedure i...","Title: Active Model-Based Hysteresis Compensation and Tracking Control of Pneumatic Artificial Muscle\nYear: 2022\n\nAbstract: The hysteretic nonlinearity of pneumatic artificial muscle (PAM) is the main factor that degrades its tracking accuracy. This paper proposes an efficient hysteresis compensation method based on the active modeling control (AMC). Firstly, the Bouc-Wen model is adopted as the reference model to describe the hysteresis of the PAM. Secondly, the modeling errors are introduced into the reference model, and the unscented Kalman filter is used to estimate the state of the system and the modeling errors. Finally, a hysteresis compensation strategy is designed based on AMC. The compensation performances of the nominal controller with without AMC were experimentally tested on a PAM. The experimental results show that the proposed controller is more robust when tracking different types of trajectories. In the transient, both the overshoot and oscillation can be successfully attenuated, and fast convergence is achieved. In the steady-state, the proposed controller is more robust against external disturbances and measurement noise. The proposed controller is effective and robust in hysteresis compensation, thus improving the tracking performance of the PAM.","Title: Active Modeling Based Control for Aerial Manipulator Systems\nYear: 2021\n\nAbstract: Expanding an unmanned aerial vehicle (UAV) with an equipped robotic arm increases the ability of the UAV to actively interact with the environment. During the process of active tasks, precise motion control under model uncertainties and external disturbances is a challenging issue. To solve this issue, an active modeling based control scheme is proposed in this paper. In this scheme, the aerial manipulator system (AMS) is modeled with consideration of various uncertainties represented by the model error and the process noise. The model error caused by the gravity and movement of the manipulator is estimated by the unscented kalman filter (UKF). The estimation is further integrated into a nominal controller to achieve high-precision motion control. Detailed experimental results on the self-bulit testbed illustrate the effectiveness and good performance of the proposed method.","Title: Plantar pressure-based temporal analysis of gait disturbance in idiopathic normal pressure hydrocephalus: Indications from a pilot longitudinal study\nYear: 2022\n\nAbstract: Background and Objective: Idiopathic normal pressure hydrocephalus (iNPH) is a common yet poten-tially reversible neurodegenerative disease, and gait disturbance is a major symptom. Lots of methodolog-ical and clinical work has been conducted on gait disturbance analysis for differential diagnosis, presur-gical test, and postsurgery assessment of iNPH. Nevertheless, the verification analysis was mostly lacking for surgery response, and the temporal characteristics of ground reaction force has been rarely investi-gated.Methods: In this work, we propose that plantar pressure features fundamentally signifies iNPH gait dis-turbance and improvement after cerebrospinal fluid (CSF) drainage by lumbar puncture tap test as well as surgical shunt implantation. The plantar pressure signals of six iNPH patients and eight healthy controls were collected, and an online database of sixteen healthy controls were used. For patients, data were collected in five periods, which are the baseline before the tap test, 8, 24, and 72 hours after the tap test, and one month after the shunt implantation surgery, respectively. Fast dynamic time warping (DTW) with an improved DTW barycenter averaging (DBA) method was proposed for temporal analysis with the measured and online plantar pressure data. An plantar-pressure variation index (PPVI) was formulated to characterize the temporal dynamic stability of walking.Results: The PPVI based on temporal analysis of plantar pressure well discriminated the impaired gait (baseline, 24 and 72 hours after tap test) with the improved gait (8 hours after tap test and follow up after surgery) of the patients. Further, the PPVI was close for the improved gait of the patients and the healthy gait measured in our study as well as in the online database.Conclusions: Plantar pressure-based temporal features are promisingly effective for clinical examination and treatment of iNPH. (c) 2022 Elsevier B.V. All rights reserved.","Title: Simultaneous Calibration of the Hand-Eye, Flange-Tool and Robot-Robot Relationship in Dual-Robot Collaboration Systems\nYear: 2022\n\nAbstract: A multi-robot collaboration system can complete more complex tasks than a single robot system. Ensuring the calibration accuracy between robots in the system is a prerequisite for the effective inter-robot cooperation. This paper presents a dual-robot system for orthopedic surgeries, where the relationships between hand-eye, flange-tool, and robot-robot need to be calibrated. This calibration problem can be summarized to the solution of the matrix equation of AXB=YCZ. A combined solution is proposed to solve the unknown parameters in the equation of AXB=YCZ, which consists of the dual quaternion closed-form method and the iterative method based on Levenberg-Marquardt (LM) algorithm. The closed-form method is used to quickly obtain the initial value for the iterative method so as to increase the convergence speed and calibration accuracy of the iterative method. Simulation and experimental analyses are carried out to verify the accuracy and effectiveness of the proposed method.","Title: A supervised independent component analysis algorithm for motion imagery-based brain computer interface\nYear: 2022\n\nAbstract: Recognizing the corresponding neural activities of independent components(ICs) obtained by independent component analysis(ICA) is of prime importance to take use of ICA in EEG analysis. There are many methods trying to solve this problem. But most of them combining ICA, a unsupervised method, and recognition of ICs in a separate way. In this paper, we propose a supervised method to extract the independent components corresponding to different motion imagery(MI) activities in the brain. By designing a new optimization objective and solving it, we combine the idea of ICA with principle of MI in an individual algorithm. From the perspective of event-related desynchronization and synchronization (ERD/ERS), specific frequency band power of the motion-related component should be enhanced or suppressed when executing or imaging movement of body. Therefore, the new optimization function extract the components that satisfy both independence and band power maximization for specific motions. Then, we solve this optimization problem based on the fixed-point iteration scheme. In the experimental stages, we show that our methods can extract motion-related independent components without losing independence. Experimental results show that, although basing on the principle of ERD/ERS, our methods’ effectiveness can be verified in the perspective of movement-related potential (MRP). Additionally, by identifying features in the extracted motion-related independent components, we can achieve better motion recognition accuracy. When using the proposed algorithms with different schema, the results yielded significant accuracy imporvements of 6.9%(p < 0.001) and 7.9%(p < 0.01).","Title: Incremental Learning Framework for Autonomous Robots Based on Q-Learning and the Adaptive Kernel Linear Model\nYear: 2022\n\nAbstract: The performance of autonomous robots in varying environments needs to be improved. For such incremental improvement, here we propose an incremental learning framework based on $Q$ -learning and the adaptive kernel linear (AKL) model. The AKL model is used for storing behavioral policies that are learned by <te...","Title: Direct Inverse Hysteresis Compensation of Piezoelectric Actuators Using Adaptive Kalman Filter\nYear: 2022\n\nAbstract: The hysteresis of the piezoelectric actuator exhibits obvious rate dependence, especially in fast scanning or tracking. This article proposes an adaptive hysteresis compensation method that integrates the direct inverse modeling (DIM) method and an adaptive Kalman filter (AKF). DIM is adopted to directly obtain the inverse hysteresis model and use it as the hysteresis compensator. AKF is utilized ...","Title: Unmanned Aerial Transportation System With Flexible Connection Between the Quadrotor and the Payload: Modeling, Controller Design, and Experimental Validation\nYear: 2023\n\nAbstract: Aerial delivery is becoming a reality due to the development of microelectronics and communication technology. Most existing methods for cable-suspended transportation systems utilize fixed-length cable to connect the unmanned aerial vehicle quadrotor and the payload. Such aerial transportation systems present underactuated property, which is caused by the indirectly controllable payload motion and the underactuation of the quadrotor itself. In practical applications, payload hoisting and lowering motion independent of the quadrotor altitude will further expand the application scope in such areas as limited space crossing and offshore sample collection. To realize the aforementioned objectives, a flexible connection between the quadrotor and the payload is realized by mounting an actuator beneath the fuselage. Suffering from strong nonlinearity and complex dynamic coupling, the control problem becomes extremely challenging and more cumbersome, as the system’s degree of freedom (DOF) increases. To deal with these problems, in this article, a nonlinear control approach is presented by energy-based analysis, which achieves simultaneous quadrotor positioning, payload swing elimination and hoisting\n<bold xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">/</b>\nlowering. Lyapunov techniques and LaSalle’s Invariance theorem are utilized to prove the asymptotic convergence of the equilibrium point. Finally, a series of hardware experiments are conducted on a self-built aerial transportation platform. As far as we know, this article provides the first mechanism and control solution for payload hoisting/lowering independent of the quadrotor altitude.","Title: fNIRS Feature Extraction and Classification in Grip-Force Tasks\nYear: 2021\n\nAbstract: It has been of increasing interest to decode the movements based on the changes in hemoglobin concentration in the cerebral cortex that can be measured by functional near-infrared spectroscopy (fNIRS). Existing work were mainly focused on motor imagery tasks for the advantages of fNIRS on cognitive activation detection, and motor tasks were not well studied. This paper investigated fNIRS feature e...","Title: An sEMG-based Hill-type Model for Estimation of Swallowing Motion\nYear: 2021\n\nAbstract: Dysphagia is a common clinical symptom which can cause dehydration, malnutrition, pneumonia, and even death. Surface electromyography (sEMG) signals, which can be obtained in a non-invasive way, have been used for screening dysphagia, and estimation of the swallowing motion based on the sEMG signals is essential. In this paper, we propose an sEMG-based Hill-type model for estimation of swallowing ...","Title: An hFFNN-LM Based Real-Time and High Precision Magnet Localization Method\nYear: 2022\n\nAbstract: Magnet tracking is an emerging tracking method for medical instruments and biological tissues, such as endoscopes and catheters. Traditional magnet tracking technology typically uses an optimization algorithm or heuristic algorithm to estimate the pose of a permanent magnet according to the measured magnetic induction intensity. However, this technology is limited by the high delay and the poor quality of the initial solution. This article proposes a new magnetic localization method, i.e., a hybrid feedforward neural network and Levenberg-Marquardt (hFFNN-LM) algorithm. FFNN provides an adjusted initial solution to the LM algorithm for solving the nonlinear inverse magnetic problem. The hFFNN-LM algorithm is promising for real-time magnetic tracking as it provides satisfactory tolerance for initially estimated parameters and fast search speed. The average single localization time is 1.07 ms. The experimental results show that the proposed method has a very low tracking delay compared to some other popular LM-based methods. The proposed hFFNN-LM algorithm achieves superior localization performances, i.e., the mean position and orientation errors are tested to be 0.70 mm and 0.90 degrees, respectively.","Title: A non-contact system for intraoperative quantitative assessment of bradykinesia in deep brain stimulation surgery\nYear: 2022\n\nAbstract: •A compact optical sensor measures patient voluntary movement without interfering.•A software monitors, analyzes and displays the movement and bradykinesia features.•The system was technically validated, and applied for 20 patients in DBS surgery.•This brings an effective solution for DBS intraoperative assessment of bradykinesia.","Title: Active model-based nonlinear system identification of quad tilt-rotor UAV with flight experiments\nYear: 2022\n\nAbstract: To propose an accurate and less complex model of a special unmanned aerial vehicle (UAV), namely tilt-rotor UAV (TRUAV), this study identifies the active model-based nonlinear system of a quad-TRUAV. First, a nominal nonlinear model of the vehicle is formulated. Some unstructured nonlinearities are ignored to reduce the complexity of the model. Then, due to the unstable dynamics of the open-loop system, the format of this nominal model is considered to design an innovative smooth-switch attitude control via interconnection and damping assignment passivity-based control (IDA-PBC). Active model-based nonlinear system identification is studied for the vehicle with the designed control method and flight experiments. The model error vector is defined and estimated by the unscented Kalman filter (UKF) to improve the accuracy of the model. The main contribution of this paper is to identify the nominal nonlinear model and to develop an active model method of the quad-TRUAV. The attitude control method with an innovative smooth-switch structure is another contribution to flight experiments. Numerical results are displayed to present the experimental results and effectiveness of the proposed nonlinear models.","Title: Modeling and Robust Control for Tendon–Sheath Artificial Muscle System <italic/>Twist<italic/> With Time-Varying Parameters and Input Constraints: An Exploratory Research\nYear: 2023\n\nAbstract: Tendon–sheath artificial muscle (TSAM) is a type of artificial muscle, which is widely used in robotic flexible endoscopies. The characteristics of the tendon force/position transmission were studied recently, but the control issue of the TSAM \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"/>\ntwist\n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"/>\n is still barely concerned. In this article, an effective robust control scheme is proposed for the TSAM \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"/>\ntwist\n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"/>\n, which achieves satisfactory tracking performance. First, a rigorous model was developed for the TSAM \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"/>\ntwist\n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"/>\n with consideration of parameters uncertainty and actuator input constraints, moreover, the disturbance of the discontinuous friction (Coulomb friction) was analyzed. Next, by applying some signal operation methods, a nonlinear robust controller was designed. In addition, the stability of the control strategy was proven theoretically by utilizing Lyapunov-based theory. Finally, a series of hardware experiments were conducted on a robotic flexible ureteroscope test-bed. The feasibility of the proposed model, the effectiveness and robustness of the designed control method were extensively validated."],"string":"[\n \"Title: UKF based estimation and tracking control of nonholonomic mobile robots with slipping\\nYear: 2007\\n\\nAbstract: A kinematic model of tracked vehicles is established in this paper, in which both longitudinal and lateral slipping is considered and processed as three time-varying parameters. Unscented Kalman filter is then introduced to real time estimate the pose and slipping parameters jointly. A stable tracking control law for this nonholonomic system is proposed and the asymptotic stability is guaranteed by Lyapunov theory. Simulation results show the efficiency and robustness of the proposed method.\",\n \"Title: Artificial Potential Guided Evolutionary Path Plan for Multi-Vehicle Multi-Target Pursuit.\\nYear: 2004\\n\\nAbstract: Path planning for multi-vehicle multi-target pursuit (MVMTP) is studied in this paper. With respect to equal number of vehicles and obstacles, a global cost function (GCF) is proposed and an optimal one-vehicle-one-target-pair appointment is specified based on the GCF. The artificial potential (AP)-guided evolutionary algorithm (EA) is used by each appointed pair to search the path that will allow the vehicle to catch the target at a specified criterion while avoiding obstacles. Both the targets and obstacles are moving in the environment, and the pair appointment can be updated regularly according to the snapshot of the uncertain environment. The integration of AP into EA is intended to achieve a convergent, fast and efficient trajectory searching mechanism that can be installed in real time. ©2004 IEEE.\",\n \"Title: A Double-Side Filter Based Power Line Recognition Method For Uav Vision System\\nYear: 2013\\n\\nAbstract: Automatic power line recognition from cluttered background is an important and challenging task for a vision based unmanned aerial vehicles (UAVs) power line inspection system. In this paper, we propose a power line recognition method based on liner object enhancement and parallel lines constraint. A new double-side filter is proposed to enhance the power lines, and then the radon transform is used to find the parallel lines as the power line recognition results. Our experiments on real image data captured from UAV demonstrate our method is effective for automatic power line recognition.\",\n \"Title: The New Evolution For Sia Rotorcraft Uav Project\\nYear: 2010\\n\\nAbstract: This paper describes recent research on the design, implement, and testing of a new small-scaled rotorcraft Unmanned Aerial Vehicle (RUAV) system-ServoHeli-40. A turbine-powered UAV weighted less than 15 kg was designed, and its major components were tested at the Shenyang Institute of Automation, Chinese Academy of Sciences in Shenyang, China. The aircraft was designed to reach a top speed of more than 20 mps, flying a distance of more than 10 kilometers, and it is going to be used as a test-bed for experimentally evaluating advanced control methodologies dedicated on improving the maneuverability, reliability, as well as autonomy of RUAV. Sensors and controller are all onboard. The full system has been tested successfully in the autonomous mode using the multichannel active modeling controller. The results show that in a real windy environment the rotorcraft UAV can follow the trajectory which was assigned by the ground control station exactly, and the new control method is obviously more effective than the one in the past year's research.\",\n \"Title: Tracking Control of Unmanned Trimaran Surface Vehicle: Using Adaptive Unscented Kalman Filter to Estimate the Uncertain Parameters\\nYear: 2008\\n\\nAbstract: This paper proposes an adaptive unscented Kalman filter (UKF) based tracking controller to force underactuated nonlinear autonomous ships to follow a reference path under constant disturbances induced by wave, wind and ocean-current. The controller development is based on MIT based UKF and backstepping techniques. The AUKF is used to update the estimation of the uncertain parameters online to avoid the parameters' drift due to time-varying added mass matrices. Along the way of tracking control, we obtain a new stability result for nonlinear underactuated systems with non-vanishing uncertainties. Simulations conducted with respect to the tracking control of unmanned ship illustrate the effectiveness of our proposed controller.\",\n \"Title: Helicopter velocity tracking control by adaptive actor-critic reinforcement method\\nYear: 2011\\n\\nAbstract: A robotic helicopter is an aircraft equipped with a sensing, computing, actuation, and communication infrastructure that allows it to execute a variety of tasks with autonomous mode. In this paper, we present an adaptive actor-critic reinforcement method to obtain near optimal controller for small autonomous helicopter. A network based on Q-value performs the critic and is trained by SARSA algorithm. A BP neural network, which is the actor network, generates control signal of helicopter dynamics. First, the proposed actor-critic reinforcement controller is introduced, then the algorithm is applied to an unmanned helicopter known as a highly nonlinear and complex system and the simulation results are presented.\",\n \"Title: Aggressive Manuevering of Unmanned Helicopters: Learning from Human Based on Neural Networks.\\nYear: 2012\\n\\nAbstract: Teaching by Showing control of a small helicopter's aggressive maneuvering often needs inner aided controllers based on helicopter's dynamics, which is very complex to identify. In this paper, a neural network based control is proposed, based on the identification of the relationship between the pilot's control and flight states, and it is a model-free control method. Flight test is done in simulation environment based on real flight data. The results show the effectiveness of the neural network based controller for aggressive flight control.\",\n \"Title: The analysis and synthesis of PID controller based on closed loop response characteristics\\nYear: 2012\\n\\nAbstract: In this paper, a new PID parameter tuning method is proposed. First, extensive analysis of the PID frequency properties is conducted. Based on the analysis results, the concept of characteristic frequency of the PID controller is proposed, which builds a relationship between the PID parameters and the oscillation characteristics of the closed loop response of the PID control system. This relationship makes it possible to adjust the PID parameters according to the oscillation characteristics of the closed loop response of the PID control system. Based on the characteristic frequency of the PID controller and the corresponding analysis results, three tuning rules of the PID parameters are proposed, which are based on the characteristics of the closed loop response. The merits of these tuning rules are: only the characteristics of the closed loop response of the control system are required in the tuning process, while the system model of the controlled object is not required. The effectiveness of these tuning rules is verified by the simulation results for several models of the controlled objects.\",\n \"Title: Trajectory Planning Of Manipulator For A Hitting Task With Autonomous Incremental Learning\\nYear: 2007\\n\\nAbstract: A new approach based on genetic algorithm (GA) and autonomous mental development for trajectory planning of robot manipulator is presented in this paper. The trajectory for the manipulator is optimized by the GA. To make the trajectory planning used in real time application, a developmental learning algorithm is proposed to generate an incremental hierarchical discriminating regression (IHDR) tree to form the mapping from the state space to the action space. Just like the human brain from infancy to adulthood, the algorithm develops its cognitive and behavioral skills through online learning from the samples obtained from the GA-based method. When the IHDR tree is generated, it can perform the trajectory planning in real time by retrieving in its knowledge database.\",\n \"Title: Kinematics/statics and workspace analysis of a 3-leg 5-dof parallel manipulator with a upu-type composite active constrained leg\\nYear: 2013\\n\\nAbstract: A novel 3-leg 5-DoF parallel manipulator PM with a UPU-type composite active constrained leg is proposed and its kinematics and statics are analyzed systematically. First, the formulae are derived for solving the inverse/forward displacements, inverse/forward velocities, and active/constraint forces. Second, the formulae are derived for solving inverse/forward accelerations. Third, a simulation mechanism of this PM is created and its workspace is constructed and analyzed. Finally, the analytic results are verified by its simulation mechanism.\",\n \"Title: Hierarchical projection regression for online estimation of elbow joint angle using EMG signals.\\nYear: 2013\\n\\nAbstract: Exoskeletons offer great facilities to the elderly and disabled people with respect to extending their moving ranges and reacting to certain physical activities. Electromyogram (EMG) signals, which are derived from the neuromuscular system, provide an important access to the human-robot interface. On one hand, EMG signals can be used for real-time estimation of the motion intention of human body, e.g., the current joint angle status. On the other hand, however, the process of the mass EMG data, which are captured instantaneously from skin surface, challenges the state-of-the-art technology. Because its non-stationary and randomness, it is difficult to extract the valuable and stable features from the raw EMG signals. This paper investigates into the learning process of high dimensional EMG signals with a hierarchical mechanism that projects the original data into a lower feature space to achieve a local refined mapping from the EMG signals to the motion states of the human body. This hierarchically projected regression algorithm constructs incrementally a tree-based knowledge library, whose components represent local regression models. The components will be retrieved online efficiently and contribute to the estimation of the motion states. A great number of experiments are carried out to evaluate the accuracy of this novel algorithm. © 2012 Springer-Verlag London Limited.\",\n \"Title: Trajectory Generation in Relative Velocity Coordinates Using Mixed Integer Linear Programming with IHDR Guidance\\nYear: 2007\\n\\nAbstract: Mixed-integer linear programming (MILP) for trajectory generation of mobile robot suffers from nonlinear constraints due to complex obstacle contours and dynamic environment. In this paper, firstly, we introduce a relative velocity coordinates MILP (RVCs-MILP) for solving the nonlinear constraints problem in the trajectory generation of the target pursuit and multiple-obstacle avoidance (TPMOA). The computational load of the RVCs-MILP does not increase with the complexity of obstacle contour but only relates to the number of the obstacles. It can be applied in real time when the number of the obstacles is small. For the large numbers of obstacles avoidance, further, we propose an IHDR based online learning mechanism. It sets up a \\\"scenario-action mapping\\\" knowledge base by continuously offline training and online updating. For a trajectory generation task, it will search a best match path of the current state in the knowledge base according to the external environments and the state of the robot in real time. Simulations are presented in comparison with the evolution algorithms (EA) and IHDR. The former shows significant improvement in a number of aspects. The latter confirms the validation of the proposed IHDR methods.\",\n \"Title: Modeling a Small-size Unmanned Helicopter Using Optimal Estimation in The Frequency Domain\\nYear: 2010\\n\\nAbstract: In this paper, a semi-decoupled state space model of a small-size helicopter is developed for hovering conditions in order to simplify the model identification process. An optimal estimation algorithm in frequency domain is proposed and implemented to estimate the parameters in the state space model using real flight data collected from a SERVOHELI-40 small-size unmanned helicopter. The accuracy of the identified model is verified by simulation in time domain, using a different set of hovering flight data. The results have shown the accuracy of the developed semi-decoupled model and the effectiveness of the proposed optimal estimation algorithm in frequency domain.\",\n \"Title: Dynamical vision sensors based active cooperative observation in three dimensional environment\\nYear: 2013\\n\\nAbstract: Vision based observation of a moving target is one of the important problems and hot issues of mobile robot system. Dynamical vision sensors which is constituted with multiple robots to obtain improved observational results has been shown to be a good substitution of single vision sensors. Thus, a new active cooperative observation (ACO) method based on two dynamical vision sensors is proposed. The most characteristics of the proposed method is that data fusion and path planning algorithm are simultaneously implemented and combined with each other by the optimal observation formation so that the influence of relative positions among MVSs and target on the cooperative observation result can be fully considered to improve the observation result. Finally, for verifying the validity and feasibility of the proposed method, experiments on a multiple rotor flying robots test-bed are conducted and analyzed, respectively.\",\n \"Title: Decentralized receding horizon control for multiple unmanned helicopters considering dynamics model\\nYear: 2009\\n\\nAbstract: In this paper, the formation flight of multiple Unmanned Helicopter (UH) systems is researched and a new decentralized receding horizon formation control algorithm is supposed. The formulation of formation control problem is firstly given where a local tracking controller for each helicopter system is supposed and the flight trajectories are taken as optimizing variables. Secondly, full dynamics of UH system is introduced into the formation control algorithm by a new concept of Formation Control Lyapunov Functions (FCLF). Subsequently, the convergence of the proposed formation control algorithm is ensured by combining the concept of FCLF and some constraints with respect to the optimized variables. Finally, in order to verify the feasibility and validity of the proposed algorithm, the formation flight simulations of 3 UH systems are conducted.\",\n \"Title: The ServoHeli-20 Rotorcraft UAV Project\\nYear: 2010\\n\\nAbstract: This paper describes research on the design, implement and testing of a small-scaled rotorcraft unmanned aerial vehicle (RUAV) system - ServoHeli-20. A turbine-powered UAV weighted less than 10 kg was designed, and its major components tested by a group of undergraduate students at Shenyang Institute of Automation, Chinese Academy of Sciences in Shenyang, China. The aircraft was designed to reach a top speed of more than 20 mps and fly a distance of more than 10 kilometers and then is going to be used as a testbed for experimentally evaluating advanced control methodologies dedicated on improving the maneuverability, reliability as well as autonomy of RUAV. Sensors and controller are implemented onboard. The full system has been tested successfully in the autonomous mode using the multi-channel decoupling PID controller. The results show that the rotorcraft UAV can follow the trajectory which assigned by the ground control station exactly in the real windy environment.\",\n \"Title: Binocular Based Moving Target Tracking for Mobile Robot\\nYear: 2009\\n\\nAbstract: Moving target tracking is an important application of computer vision. A binocular based method is presented for mobile robot to track target reliably under the effect of occlusion, transform and rotation in unstructured environment. Point features are extracted for representing the target and environment background under middle distortion, and then are matched and tracked through consecutive stereo frames by our improved MNCC algorithm. The point features are reconstructed and utilized to estimate the relative motion by Least-Square algorithm. Because the relative motion between the point features of target and robot is inconsistent to that of environment background and robot, the point features of environment background and the errors in feature tracking are removed by RANSAC algorithm. Experiment results validate the efficiency of our method.\",\n \"Title: Rotorcraft UAV actuator failure detection based on a new adaptive set-membership filter\\nYear: 2012\\n\\nAbstract: Actuator failure detection method based on a new Adaptive Extended Set-Membership Filter (AESMF) is proposed for Rotorcraft Unmanned Aerial Vehicle (RUAV). The AEMSF proposed in this paper is based on MIT method to optimize the set boundaries of process noises which may be incorrect in modeling or time-variant in operation; estimation stability and boundaries accuracy can be improved compared to the conventional ESMF. Actuator Healthy Coefficients (AHCs) is introduced into the dynamics of RUAV to denote the actuator failure model. Based on AESMF, online estimation of the AHCs can be obtained along with the flight state. With the estimated AHCs, actuator failure can be detected as soon as possible which provide valuable information for fault tolerant control. Efficiency and improvement of this method compared with other online parameters estimation methods is demonstrated by simulation using ServoHeli-20 model.\",\n \"Title: A new real-time algorithm for off-road terrain estimation using laser data.\\nYear: 2009\\n\\nAbstract: Gaussian mixture algorithm (GMA) is an effective approach for off-road terrain estimation, but still suffers from some difficulties\\n in practical applications, such as complex calculation and object abstraction. In this paper, GMA ismodified to improve its\\n real-time performance and to provide it with a potential ability of obstacle detection. First, a selection window is designed\\n based on the dominant-ellipse-principle to limit the probability distribution area of each measurement point, therefore avoiding\\n the calculation on the cells outside the dominant ellipse. Second, a clustering approach is proposed in order to distinguish\\n objects efficiently and decrease the operation area of one laser scan. Third, a virtual point vector is introduced to further\\n reduce the computational load of the mean square error matrix. The modified GMA is experimented on a tracked mobile robot,\\n and its improved performance is shown in comparison to the original GMA.\",\n \"Title: Feedback control for yaw angle with input nonlinearity via input-state linearization\\nYear: 2006\\n\\nAbstract: This paper discusses the yaw control of small-size unmanned helicopter. The yaw dynamics of helicopter involve input nonlinearity, time-varying parameters and the couplings between main and tail rotor. With respect to such a complicated dynamics, the normal PID control is difficult to realize good tracking performance while maintaining stability and robustness simultaneously. In this paper, a valid control is proposed by applying the derivative of the nonlinear function, the original system is to be extended a new system with a pseudostate variable. This approach makes it possible to avoid using the inverse of the nonlinear function and reduces the calculation load. The simulation results further demonstrate the improvements of the proposed algorithm.\",\n \"Title: A Review on Fault Diagnosis and Fault Tolerant Control Methods for Single-rotor Aerial Vehicles\\nYear: 2014\\n\\nAbstract: Faults or failures are inevitable to occur and their prompt detection and isolation are essential for the dependability of various systems and for avoiding damages to the system itself, persons and the environment. Therefore, the safety of helicopter platforms have attracted the attention of many researchers in the past two decades. In order to deal with these problems, this paper presents an overview of the recent development and current researches in the field of fault diagnosis, including analytical/model-based, signal processing-based and knowledge-based techniques, and also passive/active fault- tolerant control approaches. Among various helicopters, single-rotor aerial vehicles, i.e. manned helicopters, unmanned helicopters, two and three degree-of-freedom unmanned helicopter experimental platforms, are considered for providing an overall picture of the fault diagnosis and fault-tolerant control approaches based on the review of journal articles in last two decades, conference articles in last several years and some books.\",\n \"Title: Design And Implement Of A Rotorcraft Uav Testbed\\nYear: 2006\\n\\nAbstract: This paper describes recent research on the design and implement of a small-scaled rotorcraft Unmanned Aerial Vehicle (RUAV) system. This platform is going to be used as a testbed for experimentally evaluating advanced control methodologies dedicated on improving the maneuverability, reliability as well as autonomy of RUAV. Sensors and controller are implemented onboard. The full system has been tested successfully in the remote-controlled mode. A control scheme based on a simplified thrust-torque model, which is for the initial flight test, is also presented.\",\n \"Title: A New Fast Histogram Matching Algorithm For Laser Scan Data\\nYear: 2008\\n\\nAbstract: This paper presents a new fast histogram matching algorithm for tracking the position and orientation of robots without the help of any odometers. Histogram avoids extracting geometrical primitives from the sensor data, acts independently from odometers, and is easy to be implemented. Here, the authors employ it to analyze laser scan data. A new concept named \\\"hierarchical histogram structure\\\" is introduced for constructing and matching histograms. This structure makes full use of the information in a laser scan and speeds up the histogram matching to a satisfying level. Computational complexity analysis and experiments show the feasibility of the new algorithm both mathematically and factually.\",\n \"Title: A General Closed-Loop Framework for Multi-dimensional Sequence Processing.\\nYear: 2012\\n\\nAbstract: A novel closed-loop framework for multidimensional sequence processing is proposed in this paper. Traditional sequence-driven models are always forward, so no information is feedback to correct their outputs, which may deviate from the true values gradually due to the estimation error accumulating. To overcome the problem, the multidimensional vector in the input sequence is divided into two vectors based on its data attribute. One vector sequence generated from the original input sequence is considered as the new input sequence, and the other is considered as the measurement output sequence. The original output sequence is treated as the state sequence. Then, a closed-loop model in the state-space form is constructed, with which the states can be estimated online by filtering algorithms The feasibility of the proposed framework has been verified by using the robot inverse kinematics.\",\n \"Title: LP-based Optimal Path Planning in Acceleration Space\\nYear: 2006\\n\\nAbstract: This paper proposed acceleration space linear programming (ASLP) method for the path planning of target pursuit and obstacles avoidance (TPOA) problem in dynamic and uncertain environment. The acceleration space for TPOA problem is defined and LP algorithm is introduced into it. LP is a powerful tool for optimization but exhibits weakness when there exist nonlinear constraints or objective function. In the proposed acceleration space, the constraints and objective function of TOPA problems are inherently described as linear inequalities that can be directly solved by LP. Also, the complexity in obstacle contour does not increase the computational burden of the ASLP. Simulations are conduced with respect to the TPOA scenario including one moving target and multiple moving obstacles. The results obtained by ASLP are presented and compared with those of artificial potential guided evolution algorithm (APEA). Significant superior is demonstrated in many aspects by the comparison.\",\n \"Title: A Full-functional Simulation and Test Platform for Rotorcraft Unmanned Aerial Vehicle Autonomous Control.\\nYear: 2012\\n\\nAbstract: In this paper, a prototype Hardware in the loop (HIL) simulation and test platform for ServoHeli40 and ServoHeil120 rotorcraft unmanned aerial vehicles have been developed in Shenyang Institute of Automation, Chinese Academy of Science. This simulation system includes a 3D flight and scenery simulator, a flight control systems, a ground control station, and a RC pilot controller. Based on a semi-decoupled flight dynamic model, which is acquired from a frequency domain system identification method using real flight hovering data, an autonomous PID controller is implemented and verified in both simulation and real flight tests. To fulfill agricultural, marine and industrial applications, the application oriented functionalities of the flight control system has been developed and fully tested before deployment in the field. And it is also beneficial to further research such as human factors in operating UAV systems and UAV task load issues. © 2013 Springer-Verlag.\",\n \"Title: Noise Covariance Identification Based Adaptive Ukf With Application To Mobile Robot Systems\\nYear: 2007\\n\\nAbstract: A novel adaptive Unscented Kalman Filter (UKF) based on dual estimation structure is proposed. The filter is composed of two parallel master-slave UIKFs, while the master one estimates the states and the slave one estimates the diagonal elements of the noise covariance matrix for the master UKF. By estimating the noise covariance online, the proposed method 1 able to compensate the errors resulting from the change of the noise statistics. Such a mechanism improves the adaptive ability of the UKF and enlarges its application scope. Simulations conducted on the dynamics of an omni-directional mobile robot indicate that the performance of the adaptive UKF is superior to the standard one in terms of fast convergence and estimation accuracy.\",\n \"Title: Three-dimensional path planning for unmanned aerial vehicle based on linear programming\\nYear: 2012\\n\\nAbstract: In this paper, an approach based on linear programming (LP) is proposed for path planning in three-dimensional space, in which an aerial vehicle is requested to pursue a target while avoiding static or dynamic obstacles. This problem is very meaningful for many aerial robots, such as unmanned aerial vehicles. First, the tasks of target-pursuit and obstacle-avoidance are modelled with linear constraints in relative coordination according to LP formulation. Then, two weighted cost functions, representing the optimal velocity resolution, are integrated into the final objective function. This resolution, defined to achieve the optimal velocity, deals with the optimization of a pair of orthogonal vectors. Some constraints, such as boundaries of the vehicle velocity, acceleration, sensor range, and flying height, are considered in this method. A number of simulations, under static and dynamic environments, are carried out to validate the performance of generating optimal trajectory in real time. Compared with ant colony optimization algorithm and genetic algorithm, our method has less parameters to tune and can achieve better performance in real-time application.\",\n \"Title: An Adaptive UKF Algorithm and Its Application in Mobile Robot Control\\nYear: 2006\\n\\nAbstract: In order to improve the performance of the UKF a novel adaptive filter method is proposed. The error between the covariance matrices of innovation measurements and their corresponding estimations/predictions is utilized as the cost function. Based on the MIT rule, an adaptive algorithm is designed to online update the covariance of the process uncertainties by minimizing the cost function. The updated covariance is further fed back into the normal UKF. Such an adaptive mechanism is intended to compensate the lack on the priori knowledge of process uncertainty distribution and improve the performance of UKF for the applications such as active state and parameter estimations. Simulations are conducted with respect to the dynamics of an omni-directional mobile robot, and the results obtained by the proposed AUKF are compared with those by normal UKF to demonstrate the effectiveness and improvements.\",\n \"Title: Dynamic Feedback Tracking Control Of Tracked Mobile Robots With Estimated Slipping Parameters\\nYear: 2008\\n\\nAbstract: The trajectory tracking control problem of a tracked vehicle with slipping is considered in this paper. The slipping effects are analyzed and modeled as three time-varying parameters, which can be estimated simultaneously with robot's pose using nonlinear estimators such as unscented Kalman filter. Dynamic feedback linearization integrated with a globally exponential stabilizing state feedback is applied to achieve the tracking control objective. Simulation results are provided to demonstrate the effectiveness of proposed method.\",\n \"Title: Robust H-2 Control With Adaptive Mechanism For The Yaw Control Of Small-Scale Helicopter\\nYear: 2006\\n\\nAbstract: This paper presents a robust H-2 controller design approach to the yaw control of a small-scale helicopter mounted on an experimental platform. The yaw dynamic system is linearized into a linear system, which is modelled by an affine uncertainty model. A new robust H-2 feedback controller with adaptive mechanisms is proposed for the linear system. The feedback gains are obtained by the solutions of a series of linear matrix inequalities (LMIs). The design approach reduces conservatism inherent in robust control with a fixed gain controller and improves performances in time-response. Numerical simulations illustrate the effectiveness of the proposed methods.\",\n \"Title: An Adaptive Threshold Neural-Network Scheme for Rotorcraft UAV Sensor Failure Diagnosis\\nYear: 2007\\n\\nAbstract: This paper presents an adaptive threshold neural-network scheme for Rotorcraft Unmanned Aerial Vehicle (RUAV) sensor failure diagnosis. The approach based on adaptive threshold has the advantages of better detection and identification ability compared with traditional neural-network-based scheme. In this paper, the proposed scheme is demonstrated using the model of a RUAV and the results show that the adaptive threshold neural-network method is an effective tool for sensor fault detection of a RUAV.\",\n \"Title: ESMF based multiple UAVs active cooperative observation method in relative velocity coordinates\\nYear: 2009\\n\\nAbstract: Based on extended set-membership filter (ESMF) and the path planning method in relative velocity coordinates (RVCs), a new 3D multiple Unmanned Aerial Vehicle (UAV) systems active cooperative observation method, high precision cooperative observing a moving target by proper planning the behavior of each member vehicle, is proposed. The new method combines the ESMF based cooperative observation method and the LP-based trajectory generation method in RVCs, where the ESMF based cooperative method is used to obtain the moving target's motion state which is further used as part of the cost function to plan the UAV's behavior by using the planning method in RVCs. The contribution of this paper is: (1) the computational burden of the proposed cooperative algorithm is comparable to single ESMF algorithm; (2) the high precision observation of moving target is always obtainable by considering the optimal observation condition during trajectory planning; (3) the planning algorithm in RVCs, where the trajectory planning can be modeled as a LP problem, is used to optimize the UAV's behavior, thus, in company with (Gu, et al; 2006), the fast application of the new proposed active cooperative observation method is desirable. Finally, the simulations in 3D environments are conducted to verify the feasibility and validity of the method.\",\n \"Title: A New Nonlinear Controller Design Method Based on Control Lyapunov Function\\nYear: 2006\\n\\nAbstract: A new formulation of nonlinear controller design method based on control Lyapunov function, called generalized pointwise min-norm (GPMN) controller, is introduced in this paper by generalizing the pointwise min-norm (PMN) controller presented by Freeman etc. And combining the GPMN controller with design-via-linearization approach of nonlinear system, we can obtain a new nonlinear controller design method, which can enlarge the stability region of the design-via-linearization approach and reserve the local performance of it. And a respectively robust and constrained version of this kind of controller is also introduced by considering both model uncertainty and input constraints.\",\n \"Title: Design, implementation and experimental tests of a new generation of Antarctic rover\\nYear: 2012\\n\\nAbstract: The Arctic and Antarctic, as the harshest environments on the earth, are of great importance to the nation. The extreme environments can be harmful, even fatal, to human beings and mobile robots. To execute missions on the Antarctic in place of human, the State Key Laboratory of Robotics of Shenyang Institute of Automation, Chinese Academy of Sciences has designed three generations of Antarctic rovers. The hardware and software design and implementation of the third generation of Antarctic rover, which has been tested on the Antarctic during the 28th Chinese National Antarctic Research Expedition in 2011, will be presented in this paper. The preliminary experimental results, as introduced in the last part of the paper, suggest that the design and implementation of the hardware and software system can ensure efficiency and reliability of the rover working on the Antarctic.\",\n \"Title: A solution of mixed integer linear programming for obstacle-avoided pursuit problem.\\nYear: 2008\\n\\nAbstract: In this paper the path planning for obstacle-avoided pursuit problem (OAP) is studied. The OAP models based on the mixed integer linear programming (MILP) is presented. In the OAP models, the dynamic equation of mass point with linear damping is taken as the state equation of vehicle's motion. Integer variables are used to describe the relative position of vehicle and obstacles. \\\"Expansible Target Size\\\" is proposed to describe the pursuit process for target step-by-step. \\\"Pursuit Direction\\\" of vehicle is defined. The Isometric Plane Method selected integer variables is used to solve MILP pursuit problem. How to select the integer variables of inner point is also given. Finally, simulations are given to show the efficiency of the method.\",\n \"Title: Design and implementation of a compact RUAV navigation system.\\nYear: 2010\\n\\nAbstract: A small, low-cost, light-weight, and compact GPS/INS navigation system for a Rotorcraft UAV (RUAV) was designed and implemented on an ARM9 LPC3250 platform, and the process is discussed in this paper. Based on the characteristics of the sensors, a two-stage Extended Kalman Filter (EKF) is embedded to estimate the flight states, get rid of online noise, and fed back the results to the flight controller. Some practical problems about realizing the algorithm have been addressed. The full system has been tested successfully on a ServorHeli-40 RUAV platform. Based on this navigation system, further research in navigation and control theory can be implemented and tested experimentally. © 2010 IEEE.\",\n \"Title: Unsupervised progressive structure-from-motion for unordered images\\nYear: 2012\\n\\nAbstract: A robust progressive structure from motion (PSFM) method is proposed for unordered images. Our method can reduce accumulative error efficiently during scene dense recovery and camera motion estimation. The whole unordered images are divided into two classes: key frames and non-key frames. For key frames, superior features are selected and tracked to initialize the parameters of PSFM reliably and reduce the accumulative errors. During the implementation of PSFM, several novel and efficient strategies are proposed to detect the parameter estimation errors and remove the outliers in feature tracking. A local on-demand scheme is proposed to dramatically reduce the computing cost of sparse bundle adjustment. The experimental results from different scenes show that our method is efficient and robust in scene dense recovery and camera motion estimation.\",\n \"Title: Hovering control of UAV based on autonomous mapping approach.\\nYear: 2010\\n\\nAbstract: The autonomous learning capability of UAV (unmanned aerial vehicle) has gained more and more attentions of researchers. As far as helicopter steering is concerned, instead of calculating dynamics of UAV in a relative short interval, pilots just take their experience and consciousness instantaneously, known as similar status has similar action, to keep the helicopter hovering. The experience and the consciousness of pilots store the mapping from the similar environment to the corresponding similar decisions. Motivated by the process, we establish the UAV mapping base from environment to decision with IHDR (Incremental Hierarchical Discriminant Regression) algorithm. UAV learns to build the mapping relation offline and online alternatively. The retrieval process from the mapping base has higher efficiency for its less mathematics complexity. Simulation results show that the approach we proposed in this paper has better performance than traditional neural network. © 2010 IEEE.\",\n \"Title: Adaptive Robust Control Techniques Applied to the Yaw Control of a Small-scale Helicopter\\nYear: 2006\\n\\nAbstract: This paper presents a new robust controller design approach to the yaw control of a small-scale helicopter mounted on an experimental platform. The yaw dynamic system is linearized into a linear system, which is modelled by an affine uncertainty model. We proposed a novel robust Hinfin feedback controller with adaptive mechanisms for the linear system with guaranteed control performances. The feedback gains are obtained by the solutions of a series of linear matrix inequalities (LMIs). The design approach reduces conservatism inherent in robust control with a fixed gain controller and improves performances in time-response. Numerical simulations illustrate the theoretical results\",\n \"Title: Acceleration Feedback Control For Direct-Drive Motor System\\nYear: 2000\\n\\nAbstract: In this study, classical PD control for direct drive motor system is enhanced to suppress disturbing torque by incorporating an acceleration feedback loop. This intends to achieve a stable and high stiffness control without the need of adjusting the PD controller; either the structure or the parameters. The acceleration feedback control is presented with a focus on designing the acceleration closed-loop in terms of its stability and ability in resisting the dynamic disturbances. The sensing and modeling of angular acceleration via servo-type linear accelerometers is dealt with in viewpoint of practical implementation Extensive experiments are conducted on the second joint of a three-link direct drive robot. Results are given against those obtained by classical PD control without the acceleration feedback loop, to mainly investigate the ability of the acceleration feedback control in resisting disturbing torque, and its influence to the conventional PD control.\",\n \"Title: A novel HCI based on EMG and IMU\\nYear: 2011\\n\\nAbstract: The technology of human-computer interaction (HCI) is developing rapidly in tandem with the advancement of information and biological technologies. Many new types input device are introduced into this field; some of them are aimed to benefit special groups of people like old or disabled persons. In the meantime, Electromyography (EMG) and Inertia Measure Unit (IMU) have been readily available and extensively applied in control systems in many fields. In this paper, we propose a novel EMG-IMU based mouse controller that controls cursor movements based on IMU signals. The displacement of the cursor is determined by integrating the acceleration signal from the IMU, which moves with the operator's arm. The mouse operations such as left click, right click and wheel scroll, are commanded through EMG signals. The pattern recognition algorithm, Linear Discriminant Analysis (LDA), is adopted to classify the EMG data into several clusters, which correspond to the pre-defined mouse operations. Experimental results have indicated that the proposed mouse controller can achieve an accuracy of 88%.\",\n \"Title: Experimental study of vision sensor based multiple robots active cooperative observation using multi-RFRs testbed\\nYear: 2011\\n\\nAbstract: An experimental study of an active cooperative observation approach based on Extended Set-Membership Filter (ESMF) is completed. In the experiment, the two RFRs can keep the optimal observation formation while achieving the cooperative observation so that the observation accuracy is improved further. The most attracting advantages in this video is that the experimental results on the testbed showed the proposed method can achieve data fusion well to improve the observation accuracy and the real time performance and observation accuracy can meet the requirement of on-line application.\",\n \"Title: Active Model-Based Predictive Control and Experimental Investigation on Unmanned Helicopters in Full Flight Envelope\\nYear: 2013\\n\\nAbstract: For the control of unmanned helicopters in full flight envelope, an active model based predictive control scheme is developed in this brief. Dynamics in full envelope is modeled, with uncertainties represented by the system model error and process noise. The model error depends on both helicopter dynamics and flight mode, and the process noise is assumed unknown but bounded. Based on the set-membership filter, an active modeling based stationary increment predictive control, based on the estimated model error and its boundary to optimally compensate the model error, as well as the aerodynamics time delay, is proposed. The proposed method has been implemented on the ServoHeli-40 unmanned helicopter platform and experimentally tested; the results have demonstrated its effectiveness.\",\n \"Title: Laser scan matching using multiplex histograms with feature components\\nYear: 2009\\n\\nAbstract: A new laser scan matching algorithm is proposed in this paper. By constructing multiplex histograms, the new algorithm offers a simple way for importing geometrical features into the histogram method, obtaining more geometrical information from the laser scan data, and carrying out more accurate matching results. Also, an optimal maximum selection mechanism is employed to filter out the incorrect matching results, which further guarantees the matching precision. With the satisfactory matching results, the new algorithm shows a promising application prospect to the self-localization of robots. Experiments are performed to prove the feasibility and accuracy of the new algorithm.\",\n \"Title: Energy-aware utility optimisation for joint multi-path routing and MAC layer retransmission control in TDMA-based wireless sensor networks\\nYear: 2013\\n\\nAbstract: This paper formulates a novel energy-aware utility optimisation EUO problem for joint multi-path routing and medium access control MAC layer retransmission control in time division multiple access TDMA-based wireless sensor networks WSNs. As the EUO problem is non-convex and inseparable, we propose a heuristic method called Successive Alternating Convex Approximation SACA to approximately solve the problem. More precisely, we decompose the EUO problem into two alternating convex sub-problems, namely energy-aware multi-path routing and retransmission control. On one hand, given the time slot allocation, the multi-path routing balances the energy consumption within WSNs. On the other hand, provided the traffic distribution, retransmission control enhances the data reliability in the most energy-efficient way. These two sub-problems are solved recursively by means of dual decomposition. The sequence of optimal solutions to these two sub-problems is shown to converge to some steady-state point that approximates a solution to the EUO problem.\",\n \"Title: Dynamic Tracking Of Minimally Invasive Spine Surgery Robot\\nYear: 2013\\n\\nAbstract: In order to exhibit the surgery instruments in intraoperative image, the tracking system must be introduced so that it may finally achieve the image guide surgery on minimally invasive spine surgery (MISS). To exhibit the tip of the instrument, the transform of the CARM(a device which generates X-ray images) and CT image, the transform of the world and CARM. The more transforms of different space happen, the more errors will be introduced into the system. This paper is focused on the surgery robot tracking problem, especially for the tracking of the position and posture of the surgery instruments. We introduce a method which could establish the robot model of the surgery and show the projection of the surgery instruments on intraoperative images which could help surgeon estimate the relative position of the surgery instrument and patient's spine.\",\n \"Title: Motion planning for flexible needle in multilayer tissue environment with obstacles\\nYear: 2012\\n\\nAbstract: Flexible needle with bevel tip offers greater mobility for puncture surgery. This would expand the scope of the puncture surgery. However, motion planning for flexible needle is still a challenge due to its non-holonomic property and the complicated interactions with soft tissues. In this paper, a multilayer tissue model is constructed to simulate human tissue, and a dynamic programming is employed to plan the motion of flexible needle in the multilayer environment. In order to improve the security of the puncture process, the obstacles are fuzzed up. Then, an optimal algorithm is developed to determine a more suitable puncture angle. In addition, to deal with more complex environment, we develop a reverse algorithm to confirm the entry point in line with the target. Finally, we take some simulations to verify the proposed algorithms, and analyze the results.\",\n \"Title: Kinematics, Statics And Stiffness Analysis Of N(4-Sps+Sp) S-Pm\\nYear: 2012\\n\\nAbstract: A novel n(4-SPS+SP) serial-parallel manipulator (S-PM) formed by n 4-SPS+SP PMs with four degrees of freedom (DOF) connected in series is proposed in this paper. The kinematics, statics and stiffness model of this serial-PM is established. First; the forward kinematics of 4-SPS+SP (spherical joint-prismatic joint-revolute+spherical joint-prismatic joint) PM is derived and the kinematics of n(4-SPS+SP) S-PM is studied combined with the kinematics result of single 4-SPS+SP PM. Second, the statics; deformation and stiffness of n(4-SPS+SP) S-PM are studied. Finally, an analytically solved example is given for 3(4-SPS+SP) formed by three 4-SPS+SP PMs. The method for this mechanism is fit for other S-PMs.\",\n \"Title: Design and implementation of multiple-rotorcraft-flying-robot testbed\\nYear: 2011\\n\\nAbstract: In this paper, a multiple-rotorcraft-flying-robot (MRFR) testbed is introduced. Firstly, physical structure, as well as hardware and software system, is described in detail. Subsequently, in order to realize the autonomous flight of each single rotorcraft-flying-robot (RFR), modeling, identification and flight control experiments are conducted. Then, formation flying demonstration is presented to verify the basic functions of the new-designed MRFR testbed. Finally, two points should be emphasized: 1) both cooperation/coordination algorithm of MRFR and advanced flight control algorithm of single RFR can be verified on this testbed; 2) experiments on this testbed can approach real flight test much better because three real RFR systems are used.\",\n \"Title: Theoretical and experimental study of uncertain set based moving target localization using multiple robots.\\nYear: 2011\\n\\nAbstract: In this paper, multiple robots cooperation based moving target localization problem is researched. Different from traditional statistics based architecture, the concept of uncertain set is utilized in this paper to formulate the so called Cooperative Enhanced Set Membership Filter based cooperative localization algorithm. One of the most attracting advantages of this method is that it assumes the measurement errors are modeling as unknown-but-bounded set, instead of requiring the errors' covariance to be obtainable beforehand, which is general in statistics based algorithm, such as Kalman Filter and Particle Filter. Furthermore, some strategies, which is originated from the update process of the ESMF algorithm itself, are proposed to improve the computational efficiency and localization accuracy. Finally, an original experimental scenario is designed with respect to an indoor multiple-rotorcraft-platform and the results are listed out and analyzed in detail to verify the feasibility and validity of the proposed algorithm. © 2011 IEEE.\",\n \"Title: Feasibility of EMG-based ANN controller for a real-time virtual reality simulation\\nYear: 2012\\n\\nAbstract: Estimation of the joint angle from the surface electromyography (sEMG) is a quite complex task due to the complicated relationship between the kinematical variables and the raw sEMG. In this paper, we build a sEMG-to-motion model with the artificial neural network (ANN). EMG features, including Integral of absolute value (IAV), Zero crossing (ZC), Auto-regression coefficients (ARC), Median frequency (MDF), are extracted as the input of the ANN, and the output of the ANN is the operator's elbow joint angle and the wrist motion. In addition, a 3D upper extremity model, which is built in SolidWorks and then transformed into MATLAB, will imitate the operator's motion simultaneously with the estimations of the ANN. Thus, we accomplish a virtual reality system to realize the real-time simulation and validate the effectiveness of the sEMG-to-motion model. Experiment results show that the system achieves well in model accuracy, hardware compatibility and real time performance with a small mean square error of 1.921 degrees.\",\n \"Title: High voltage transmission line detection for uav based routing inspection\\nYear: 2013\\n\\nAbstract: The Hough Transform (HT), the Radon Transform (RT) and the Line Segment Detector (LSD) are the most well-known methods for line detection. But the HT and RT methods cost large computing consumption and always resulting a poor performance with many outliers. The LSD method is not effective to the real application of complex background condition. In this paper, a boundary search radon transform (BSRT) approach is proposed for high voltage transmission line detection in Unmanned Aerial Vehicle (UAV) based routing inspection. The core idea assumes that the initial point of an integral line is on one of the four image boundaries, so it isn't always necessary to analyze all points in an image and a new line detection strategy is designed. Comparing to the HT, RT and LSD methods, our method is validated by the experimental results to be fast, efficient and reliable to complex environments.\",\n \"Title: High gain disturbance observer and its application in robust control attenuation\\nYear: 2013\\n\\nAbstract: High gain observer (HGO) has been proved to be a good method to estimate states of Lipschitz nonlinear systems. In this paper, we focus on the HGO based external input (disturbance) estimator and disturbance attenuation control scheme. Firstly, a robust control scheme is proposed to attenuate the disturbance with the assumption that it is obtainable; subsequently, HGO is designed to estimate both the states and the disturbances, and the convergence is ensured under some conditions; then, it is shown that if the gain of the HGO is selected properly, the BIBO stability of the whole system (nonlinear closed system with observer) can be guaranteed; finally, simulation with respect to an inverted pendulum is carried out and the results verify the validity of the proposed scheme.\",\n \"Title: Establishing dynamic model for mobile CARM\\nYear: 2013\\n\\nAbstract: Mobile CARM is a more and more important device for spine surgery navigation. The accuracy of the intraoperative image has a huge influence on the surgery success rate. For the purposes to achieve the surgery, the image capture device should be modeled by an accurate method. This paper describes the problems of establishing the CARM model. By analysis the structure of the mobile CARM, we establish the static model of the CARM. Next by kinematics analysis, we establish the dynamic model which could guarantee the accuracy of the CARM. Last we confirm the deviation of CARM images.\",\n \"Title: Power Line Detection Based On Symmetric Partial Derivative Distribution Prior\\nYear: 2013\\n\\nAbstract: In this paper, we propose a simple but effective image prior-symmetry partial derivative distribution to detect power lines in aerial image for UAVs. The symmetry partial derivative distribution is a kind of statistics of the images. It is based on a key observation-most nature images have symmetry partial derivative distributing. Based on this prior knowledge, we use radon transformation in partial derivative image and recognize the power lines in the aerial image. The experiment results demonstrate our method is effective for automatic power line detection.\",\n \"Title: A Novel Adaptive Unscented Kalman Filter For Nonlinear Estimation\\nYear: 2007\\n\\nAbstract: The normal unscented Kalman filter (UKF) suffers from performance degradation and even divergence while mismatch between the noise distribution assumed to be known as a priori by UKF and the true ones in a real system. In this paper, a novel adaptive UKF (AUKF) is developed and applied to nonlinear joint estimation of both time-varying states and parameters. A cost function is built based on the error between the covariance matrices of innovation and their corresponding estimations. An adaptive algorithm is then designed to online update the covariance of the process noise by minimizing the cost function. The updated covariance is further fed back into the normal UKF. As a result of using such an adaptive mechanism, the robustness of conventional UKF is substantially improved with respect to the uncertain and time-varying noise covariance in the real system. To illustrate this mechanism, simulations are conducted on the dynamics of an unmanned helicopter by jointly estimating both the states and model errors. The improvements of the proposed AUKF are demonstrated by comparing the results with and without the adaptive mechanism.\",\n \"Title: An Enhanced Adaptive Set-Membership Filter For Nonlinear Ellipsoidal Estimation\\nYear: 2007\\n\\nAbstract: The extended set-membership filter (ESMF) for nonlinear ellipsoidal estimation suffers from numerical instability, computation complexity, as well as the difficulty in filter parameter selection. In this paper, a UD factorization-based adaptive set-membership filter (AESMF) is developed and applied to nonlinear joint estimation of both time-varying states and parameters. As the result of using the proposed UD factorization, combined with a new sequential and selective measurement update strategy, the numerical stability and real-time applicability of conventional ESMF are substantially improved. Furthermore, an adaptive selection scheme of the filter parameters is derived to reduce the computation complexity and achieve sub-optimal estimation. Simulation results have shown the efficiency and robustness of the proposed method.\",\n \"Title: Nonlinear model predictive control enhanced by generalized pointwise min-norm scheme\\nYear: 2007\\n\\nAbstract: Nonlinear Model predictive control (NMPC) suffers from the problems of closed loop instability and computation complexity, which greatly limits its application in mechatronic systems involving fast time-varying dynamics. In this paper, a new NMPC enhanced by generalized pointwise min-norm (GPMN) scheme is presented. First, a generalized min-norm control algorithm is developed by introducing a guide function into Freeman's pointwise min-norm control (PMN) algorithm in order to obtain a stable controller based on a known CLF. Then, the guide function is parameterized according to the Bellman's optimization principle and the GPMN scheme is further integrated into normal NMPC strategy. As a result, the closed loop stability of NMPC is guaranteed and the real-time applicability is substantially improved. Simulation results have shown the efficiency of the proposed method.\",\n \"Title: Yaw Control of Small-scale Helicopter with Time-varying Uncertainty: an Adaptive Robust H2 Control Approach\\nYear: 2007\\n\\nAbstract: This paper is concerned with the robust H2 tracking control problem for the yaw control of a small-scaled helicopter with time-varying uncertainty. The proposed controller incorporates an adaptation mechanism, which improves the performance of system compared with conventional robust controller with a fixed gain. Simulation results of the yaw control of a small-scaled helicopter mounted on an experiment platform have demonstrated the theoretic results.\",\n \"Title: Milp-Based Trajectory Generation In Relative Velocity Coordinates\\nYear: 2007\\n\\nAbstract: Mixed-integer linear programming (MILP) for trajectory generation of mobile robot suffers from nonlinear constraints due to complex obstacle contours and dynamic environment. In this paper, relative velocity coordinates (RVCs) are proposed for solving the target pursuit and multiple-obstacle avoidance (TPMOA) problem. In the proposed RVCs, nonlinear constraints can be inherently described as linear inequalities, which allow MILP to be utilized to find the optimal trajectory satisfying the linear inequalities. The complexity of obstacle contour does not increase the computational load of the proposed approach. Simulation results are presented in comparison with those of evolutionary algorithm (EA), showing significant improvement in a number of aspects.\",\n \"Title: Rotorcraft UAV actuator failure estimation with KF-based adaptive UKF algorithm\\nYear: 2008\\n\\nAbstract: A new adaptive Unscented Kalman Filter (UKF) algorithm for actuator failure estimation is proposed. The novel filter method with adaptability to statistical characteristic of noise is presented to improve the estimation accuracy of traditional UKF. The algorithm with the adaptability to statistical characteristic of noise, named Kalman Filter (KF) -based adaptive UKF, is proposed to improve the UKF performance. Such an adaptive mechanism is intended to compensate the lack of a prior knowledge. The asymptotic property of the adaptive UKF is discussed. The Actuator Healthy Coefficients (AHCs) is introduced to denote the actuator failure model while the adaptive UKF is employed for on-line estimation of both the flight states and the AHCs parameters of rotorcraft UAV (RUAV). Simulations are conducted using the model of SIA- Heli-90 RUAV of Shenyang Institute of Automation, CAS. The results are compared with those obtained by normal UKF to demonstrate the effectiveness and improvements of the adaptive UKF algorithm. Besides, we also compare this algorithm with the MIT-based one which we propose in previous research.\",\n \"Title: LP-based path planning for target pursuit and obstacle avoidance in 3D relative coordinates\\nYear: 2010\\n\\nAbstract: A linear programming (LP) based approach is proposed for the trajectory generation in three dimensional space in which a vehicle is requested to pursue a moving target and avoid static or dynamic obstacles simultaneously. The target pursuit and obstacle avoidance (TPOA) are modeled in relative velocity coordinates, respectively, with linear constraints, according to the LP framework. Two objective functions are defined in terms of relative distance and relative velocity for the optimization. Other constraints, such as those from kinematics, dynamics, and sensor range are fully considered in the proposed method. Simulations are carried out to validate the method.\",\n \"Title: Knowledge-driven path planning for mobile robots: relative state tree\\nYear: 2015\\n\\nAbstract: Path planning is important in the field of mobile robot. However, traditional path planning techniques optimize the navigation path solely based on the models of the robot and the environments. Owing to the time-varying environment, the robot is expected to launch the replanning procedure in real-time continuously. It is slow and wastes computing resources for repeated decisions. In this study, a new perspective is adopted which utilizes a knowledge-driven approach for path planning. The concept of relative state tree is proposed to develop an incremental learning method based on a path planning knowledge base. The knowledge library, which stores a collection of the mappings from environmental information to robot decisions, can be established by offline or online learnings. As the robot plans online, its movement is guided by the optimal decision that is retrieved from the library based on the information which matches mostly the current environment. A large number of simulations are executed to verify the proposed method. When comparing to $$k$$ k -d tree, this novel method has shown to use smaller storage space and have higher efficiency.\",\n \"Title: Missing-data Classification with the Extended Full-dimensional Gaussian Mixture Model: Applications to EMG-based Motion Recognition\\nYear: 2015\\n\\nAbstract: Missing data is a common drawback that pattern recognition techniques need to handle when solving reallife classification tasks. This paper first discusses problems in handling high-dimensional samples with missing values by the Gaussian mixture model (GMM). Since fitting the GMM by directly using high-dimensional samples as inputs is difficult due to the convergence and stability issues, a novel method is proposed to build the high-dimensional GMM by extending a reduced-dimensional GMM to the full-dimensional space. Based on the extended full-dimensional GMM, two approaches, namely, marginalization and conditional-mean imputation, are proposed to classify samples with missing-data in online phase. Then, the proposed methods were employed to recognize hand motions from surface electromyography (sEMG) signals, and more than 75% of classification accuracy of motions can be obtained even if 50% of sEMG signals were missing. Comparisons with normal mean and zero imputations also demonstrate the improvements of the proposed methods. Finally, a control scheme for a myoelectric hand was designed by involving the novel methods, and online experiments confirm the ability of the proposed methods to improve the safety and stability of practical systems.\",\n \"Title: Active Persistent Localization of A 3D Moving Target under Set-Membership Uncertainty Description through Cooperation of Multiple Mobile Robots\\nYear: 2015\\n\\nAbstract: The persistent localization of moving targets is one of the most important applications of mobile robot systems. However, the sensors on each individual robot are often not sufficiently accurate for this task, presenting a severe limitation on the application of robots to many situations. To overcome this problem, systems of multiple robots have been established. These systems improve the localization accuracy of mobile targets by fusing together multiple sensing data. Numerous studies have demonstrated that the relative motion (or specifically, the relative pose) between the robot and the target, as well as that among different robots, strongly influences the final localization accuracy of the data fusion algorithm. In other words, the regulation of motion in a multiple robot system will lead to better localization results. Thus, in this paper, a new active persistent localization (APL) scheme is proposed. The underlying concept of this scheme is based on set-membership descriptions of uncertainties. The basic problem is formulated in the framework of an enhanced set-membership filter, and a new data fusion algorithm with improved accuracy and convergence properties is designed. A motion planning algorithm is then incorporated under the socalled optimal localization condition to complete the APL scheme. Simulations using multiple 3D mobile robot systems and experiments on a multiple rotor-flying-robot testbed show that the proposed algorithm successfully enhances the accuracy of the persistent localization of moving target.\",\n \"Title: Identification of tissue types and boundaries with a fiber optic force sensor.\\nYear: 2014\\n\\nAbstract: The absence of tactile force information at the tip of a medical instrument makes precise minimally invasive surgery difficult and is prone to resulting in serious outcomes. In this paper, a fiber optic force sensor is fabricated based on Fabry-Perot interferometry and integrated with a puncture needle. The force sensor is attached to the needle tip, where interactive force arises as it inserts into soft tissue. Needle insertion experiments have been conducted on ex vivo swine liver and belly with the calibrated force sensor. Using wavelet transform method, the acquired force data are analyzed and used to identify layered tissue types and boundaries. We found that the force amplitudes are not always identical, but the patterns of forces are almost the same, which enables us to identify layered tissues and to realize a safe needle insertion procedure under robot control.\",\n \"Title: Coordinative Dynamics Analysis Of A Parallel Manipulator With Three Grippers\\nYear: 2014\\n\\nAbstract: A kinetostatic model and a dynamics model of a parallel manipulator (PM) with three grippers are established and analyzed in the light of its application. First, the coordinative kinematics of this manipulator and three grippers are analyzed. Second, the kinetostatic formulae are derived for transforming the coordinative kinematics and forces applied on the grippers into the workloads applied on the moving platform and the active/constrained forces and torques applied onto active legs. Third, the dynamics formulae are derived for solving dynamic active wrench of grippers and PM by considering inertial mass of the grippers, legs and platform. Finally, a numerical example is given for illustrating application of kinetostatic model and dynamics formulae, and the dynamics solutions of this manipulator are verified by simulation.\",\n \"Title: Stiffness And Elastic Deformation Of A 3-Leg 5-Dof Parallel Manipulator With One Composite Leg\\nYear: 2014\\n\\nAbstract: The stiffness and elastic deformation of a 3-leg 5-DoF parallel manipulator (PM) with asymmetrical structure and composite active legs are studied systematically. First, a 3-leg 5-DoF 2SPS + PRRPR PM with asymmetrical structure and composite active legs is constructed and its structure constraint characteristics are analyzed. Second, the formulae are derived for solving the elastic deformation and the compliance matrix of the asymmetrical active legs, an asymmetrical stiffness matrix is established for this PM and the elastic deformations of moving platform and legs are solved and analyzed. Finally, a finite element (FE) model of this PM is constructed and the simulation solutions of the elastic deformations of the moving platform are obtained and analyzed. The analytic solutions of the elastic deformations of this PM are verified by its FE simulation solutions.\",\n \"Title: Simultaneous state and parameter estimation based actuator fault detection and diagnosis for an unmanned helicopter\\nYear: 2015\\n\\nAbstract: AbstractAbstract Simultaneous state and parameter estimation based actuator fault detection and diagnosis FDD for single-rotor unmanned helicopters UHs is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on actuator healthy coefficients AHCs, which are introduced to represent actuator faults, a combined dynamic model is established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for fault tolerant control FTC. Based on the existing widely used nonlinear estimation methods such as the unscented Kalman filter UKF and the extended set-membership filter ESMF, three kinds of adaptive schemes KF-UKF, MIT-UKF and MIT-ESMF are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to unmanned helicopter actuator FDD.\",\n \"Title: Kernel-Reliability-Based K-Means (Krkm) Clustering Algorithm And Image Processing\\nYear: 2014\\n\\nAbstract: In this paper, we introduced a novel Kernel-Reliability-based K-Means (KRKM) clustering algorithm for categorizing an unknown dataset under noisy condition. Compared with the conventional clustering algorithms, the proposed KRKM algorithm will measure both the reliability and the similarity for classifying data into its neighbor clusters by the dynamic kernel functions, where the noisy data will be rejected by being given low reliability. The reliability for classifying data is measured by a dynamic kernel function whose window size will be determined by the triangular relationship from this data to its two nearest clusters. The similarity from a data item to its neighbor clusters is measured by another adaptive kernel function which takes into account not only the similarity from data to clusters but also that between its two nearest clusters. The main contribution of this work lies in introducing the dynamic kernel functions to evaluate both the reliability and similarity for clustering, which makes the proposed algorithm more efficient in dealing with very strong noisy data. Through various experiments, the efficiency and effectiveness of proposed algorithm have been confirmed.\",\n \"Title: Quartic Bézier curve based trajectory generation for autonomous vehicles with curvature and velocity constraints\\nYear: 2014\\n\\nAbstract: To generate local trajectory between initial states and target states for autonomous vehicles, a feasible trajectory generation algorithm based on quartic Bézier curve is proposed. The problem of trajectory generation is firstly separated into generating continuous and bounded curvature profile to shape the trajectory and generating linear velocity profile to execute the trajectory. The curvature profile generation is further converted to an optimization problem with only 3 parameters owing to the specific properties of quartic Bézier curve. Sequential quadratic programming is employed to find optimal solution with respect to specific objective function. To avoid sideslip and ensure velocity-continuity and acceleration limits, the framework of linear velocity profile generation is also proposed. A simple profile with constant acceleration is also provided as an example. Simulation results on lane keeping and changing and path following demonstrate the capability and the real-time performance of the proposed algorithm.\",\n \"Title: A comparative study on PCA and LDA based EMG pattern recognition for anthropomorphic robotic hand\\nYear: 2014\\n\\nAbstract: A multifunctional myoelectric prosthetic hand is a perfect gift for an upper-limb amputee, however, the myoelectric control for a prosthetic hand is not so good now. Here, the paper presents a comparative study on electromyography (EMG) pattern recognition based on PCA and LDA for an anthropomorphic robotic hand. Four channels of surface EMG (sEMG) signals were recorded from the subject's forearm. Time-domain analysis, frequency-domain analysis, wavelet transform analysis, nonlinear entropy analysis and fractal analysis were done and fourteen kinds of features were extracted from sEMG signals. The features were divided into four groups, and the performances of the four groups were compared and analyzed. In the feature projection stage, three schemes were proposed and their performances were compared with each other. The first one only used the principal component analysis (PCA) for dimension reduction. And the second one only used the linear discriminant analysis (LDA) for dimension reduction. The third one used PCA for the first step of dimensionality reduction, and then used LDA for the next step of dimensionality reduction. In the classification stage, minimum distance classifier (MDC) was employed for identifying nine kinds of hand/wrist motions in the projected space. Comparative experiments of four groups of features and three projection schemes were done and evaluated. The online experiment of real-time myoelectric control for an anthropomorphic robotic hand was done as well.\",\n \"Title: Quasi-LPV modeling and identification for a water-jet propulsion USV: An experimental study\\nYear: 2014\\n\\nAbstract: For an Unmanned Surface Vehicle (USV) system, it is difficult to obtain a precise system model. This is mainly because the USV system is, (1) of extensively complicated and thus presents huge nonlinearities, and (2) easily to be influenced by extensive hydrodynamics. In this paper, our main motivation is to construct a quasi-Linear Parameter Varying (qLPV) dynamical model for a water-jet propulsion USV. The main content of this paper includes two steps: first, theoretical deduction of the qLPV model structure of the USV system is given in detailed including the hydrodynamics; after that, experiments are conducted and the parameter identification results are analyzed to show the priority of the qLPV model compared to some other often referred to models.\",\n \"Title: Dynamics modeling and performance comparisons of two different rotor flying manipulators: Main-tail-rotor vs eight-rotor\\nYear: 2014\\n\\nAbstract: Rotor flying manipulator (RFM) is a system composed of a rotorcraft and a manipulator. RFM possesses great potential applications and thus has got much concern of the researchers all over the world. However, controller design of the RFM is challenging because of the dynamical coupling between the rotorcraft and the manipulator perplexes the whole system model structure, so the flight performance of the system is more sensitive to some uncertainty factors. Generally, the rotorcraft system of the RFM can be a main-tail-rotor helicopter or multi-rotor aircrafts, which are of completely different flight characteristics. Thus, it is valuable to conduct quantitative coupling analysis of the RFM with different flight platforms. This paper is aimed at this problem. We first construct the dynamics model of the RFM system with respect to different flight platforms, respectively. Then, coupling force and moment are computed quantitatively, and the comparative analysis on the influence of the motion state on them is conducted. Finally, some conclusions are given to show different performances of different kinds of RFM systems.\",\n \"Title: Two time-scale model based adaptive control for helicopter under unknown wind conditions\\nYear: 2014\\n\\nAbstract: Two time-scale model based adaptive control method is proposed for a helicopter to overcome wind disturbances in this paper. Wind disturbances are considered as a mixture of four sinusoidal signals with unknown frequencies, amplitudes and phases. The controller is designed based on the concept of time-scale separation, which has the advantage of decoupling of the rotational and translational dynamics. Backstepping control and inverse dynamic control method are used to design the fast controller and the slow controller individually and different control intervals are used for the two models. Unscented Kalman filter (UKF) is used for online estimation of wind disturbances. The results from UKF are used for the adaptive reconfiguration of the two time-scaled model based controller. Simulation results show that the adaptive control method reduces the impact of wind disturbances and achieves good performance.\",\n \"Title: SSVEP based brain-computer interface controlled functional electrical stimulation system for upper extremity rehabilitation\\nYear: 2014\\n\\nAbstract: Brain-computer interface (BCI) is currently developed as an alternative technology with a potential to restore lost motor function in patients with neurological injuries. In this paper, we describe an integrated system of a non-invasive electroencephalogram (EEG)-based BCI with a non-invasive functional electrical stimulation (FES). This system enables the direct brain control of upper limbs to achieve motor rehabilitation. The EEG signals based on steady-state visual evoked potential (SSVEP) were used in the BCI. The classifier of linear discriminant analysis was applied to deal with the frequency domain characteristics and recognize intentions. The identified intentions were transformed into instructions to trigger FES which was controlled with iterative learning control method to stimulate the relevant muscles of upper limbs for motor recovery. Results show that the integration of BCI with an upper-extremity FES is feasible with an average accuracy of about 73.9% over five able-bodied subjects.\",\n \"Title: Detection of collapsed buildings with the aerial images captured from UAV\\nYear: 2016\\n\\nAbstract: Abstract In this paper, we present a method of detecting the collapsed buildings with the aerial images which are captured by an unmanned aerial vehicle (UAV) for the postseismic evaluation. Different from the conventional methods that apply the satellite images or the high-altitude UAV for the coarse disaster evaluation over large area, the purpose of this work is to achieve the accurate detection of collapsed buildings in small area from low altitude. By combining the motion and appearance features of collapsed buildings extracted from successive aerial images, each pixel in the input image will be measured by a statistical method where the background pixels will be penalized and the ones of collapsed buildings will be assigned with high value. The candidates of collapsed buildings will be established by integrating the extracted feature points into local groups with the online clustering algorithm. To reduce the false alarm caused by the complex background noise, each predicted candidate will be further verified by the temporal tracking framework where both the trajectory and the appearance of a candidate will be measured. The candidate of collapsed buildings that can survive through long time will be considered as true positive, otherwise rejected as a false alarm. Through extensive experiments, the efficiency and the effectiveness of proposed algorithm have been proved.\",\n \"Title: sEMG based quantitative assessment of acupuncture on Bell’s palsy: an experimental study\\nYear: 2015\\n\\nAbstract: Acupuncture is a traditional Chinese therapeutic method, recognized by western medicine as an important complementary therapy. However, the efficacy assessment of this traditional intervention has been mainly empirical rather than scientific. In this paper, we propose a surface electromyography (sEMG) based approach for quantitative assessment of acupuncture on Bell’s palsy. The assessment is made by comparing the muscle activities of healthy with diseased ones. A feature-vector of four individual sEMG features is introduced for more comprehensive representation of muscle activity. A clustering technique is then proposed to calculate quantitative differences between the muscle activities of the healthy and diseased sides. A regressive model is also proposed to predict the recovery trend of a patient based on the quantitative assessments during his/her clinical acupuncture history. As reported in the paper, a total of 20 selected Bell’s palsy patients have participated in the extensive experiments that were conducted to verify the performance of the proposed method.\",\n \"Title: Digital Comparator In Excitable Chemical Media\\nYear: 2015\\n\\nAbstract: It is well established that spatial excitable media can be used for information processing. A single excitation pulse can represent one bit of information and a group of excitations forms a message. Different structures designed can realize different functions of infonnation processing. In this paper, we systematically designed structures of digital comparator, and numerical simulations have been carried out to show that these structures can realize the function of digital comparator well. Firstly we designed one-bit and two-bit digital comparator, and then we successfully designed three-bit digital comparator in two different ways, thus we demonstrated two expanding ways to realize the multi-bit digital comparator: nesting way and cascading way. We believe that the realization of digital comparator is helpful for the constructions of other logic and arithmetic functions, and ultimately can bring great potential applications for the implementation of chemical computer and other intelligent systems.\",\n \"Title: Wave-Based Tracking Control of a Flexible Arm Using Lumped Model.\\nYear: 2014\\n\\nAbstract: A wave control is presented to suppress vibration at the distal end of a flexible robotic arm while achieving accurate tracking control. It assumes the arm with an actuator at one end and a load at the other, and interprets the arm's dynamics with a lumped model in terms of mechanical waves entering and leaving the arm at the actuator-arm interface. Control input to the actuator is then resolved into two superposed waves, which the actuator launches and absorbs simultaneously. From the motion start-up, the launch wave is assigned to the actuator, to which the absorbing wave is added. The absorbing wave is computed with the delayed tip motion. It absorbs the vibratory energy within the arm, and prevents the wave returning from the arm tip from entering the control system again. The control system's properties are investigated, and it works pretty well for trajectory tracking control, as demonstrated in the numerical results.\",\n \"Title: Assessment of the Effectiveness of Acupuncture on Facial Paralysis Based on sEMG Decomposition.\\nYear: 2014\\n\\nAbstract: Although acupuncture has been extensively and routinely applied in clinic around the world, its use is conventionally based on empirical knowledge rather than scientific evidence. In this paper, we investigate the surface electromyographic (sEMG) activity on the face of patients with facial paralysis to validate the effectiveness of acupuncture. sEMG decomposition method is employed to quantify of the differences between the healthy and diseased sides, which includes 2 parts: to decompose sEMG into motor units action potential trains (MUAPTs) with Gaussian Mixture Model (GMM); to assess the recovery of patients with facial paralysis according to the differences between the MUAPTs of healthy and diseased sides. Finally, an auto-regression model is used to predict the recovery trends. Results indicate that the proposed method can assess the effectiveness of acupuncture on facial paralysis and achieve a high accuracy of 90.94% to predict the recovery trends.\",\n \"Title: Shape Reconstruction And Attitude Estimation Of Bevel-Tip Needle Via Ct-Guidance\\nYear: 2015\\n\\nAbstract: The bevel-tip flexible needle is an improvement of the traditional rigid needle and has the potential to reduce traumas, improve the controllability and reach multi-targets in one insertion. The needle steering robot system has the ability to deal with complex puncture environment and to improve the puncture precision, but it requires a precise feedback of needle tip's position and attitude. Computerized tomography (CT) is a widely available imaging system that provides precise and clear images. Unfortunately, CT is not a real-time system and it is impossible to fetch the attitude of bevel-tip needle from CT image. A new method is proposed to estimate the attitude, in which the unscented kalman filter is employed. We extract the positions of the needle in CT images, reconstruct the needle shape, calculate the control quantity according to the insert distance and then estimate the attitude of the needle tip. Simulations and experiments demonstrate that the method proposed is effective. Implementation of shape reconstruction and attitude estimation of the bevel-tip needle in biological tissue is a significant step toward the precise control of bevel-tip needles.\",\n \"Title: Invariant-Set-Based Planning Approach For Obstacle Avoidance Under Vehicle Dynamic Constraints\\nYear: 2015\\n\\nAbstract: Autonomous vehicles require the ability to safely operate under both external environment constraints such as obstacles, and their own limits such as dynamic conditions. The problem of planning feasible control reference inputs against both constraints is still an open question. In this paper, the contribution is to propose an Invariant-Set-Based Planning (ISBP) approach which can move a vehicle from an initial point to a goal point by calculating feasible control reference inputs with satisfying both constraints simultaneously. A series of invariant sets will be calculated to cover feasible path and system input constraints will be novelly modified to calculate each invariant set. Finally, ISBP approach will be achieved by solving a set of linear matrix inequalities (LMIs).\",\n \"Title: Input-Output Response Based Simultaneous Tracking And Disturbance Attenuation Control For Helicopter Image Stabilizers\\nYear: 2015\\n\\nAbstract: Image stabilizer is important for most unmanned helicopter system. Usually it should be able to drive the video sensor to track some targets precisely under heavy vibration due to the high speed rotation of the rotor. This is the so-called simultaneous tracking and disturbance attenuation control (STDA) problem. In this paper, a new 2DOF control strategy is proposed aiming at the STDA problem. The proposed control is composed of inner loop control, which is used to attenuate the disturbance due to helicopter's vibration, and a prefilter, which is outside the closed loop and used to ensure the transient performance of the whole system. One of the most absorbing advantages of the new proposed method is that the two parts are decoupled completely and thus can be designed separately. For inner loop control, an AFC enhanced PID control is proposed to realize disturbance suppression, while for the prefilter, a new parameter optimization algorithm is introduced to ensure optimal step tracking without influencing the disturbance attenuation performance. Furthermore, it should be pointed out that the whole controller is designed based on only input-output response independent on accurate model information of the system. Finally, experiments are conducted on a real image stabilizer with simulated vibration, and the results show the feasibility and validity of the proposed method.\",\n \"Title: Multi-Relation Octomap Based Heuristic Icp For Air/Surface Robots Cooperation\\nYear: 2015\\n\\nAbstract: In this paper, we focus on the problem of fast and accurate featureless registration of outdoor large scale 3D point-clouds which possess great differences in the aspects of both resolution and view of point. There are two main methods generally used to solve this problem: feature based algorithm and point based one. However, feature based method can only be used in very special environments with clear geometric structure, while traditional point based method can only obtain a relative coarse estimation and is sensitive to initial alignment. Thus, in this paper, a registration algorithm, called Octree Based Multiresolution Heuristic ICP, is proposed.Without relying on the good initial registration and marked features, hybrid-ICP combines different ICP algorithms, and improve the alignments using finer levels of representation.In our outdoor riverside environments experiments, our method outperform the classical point based registration algorithm with an accuracy of 7 times better than classical Generalized-ICP and a speedup 1.6 times.\",\n \"Title: Real-Time Data Acquisition and Model Identification for Powered Parafoil UAV.\\nYear: 2015\\n\\nAbstract: Powered Parafoil UAV PPUAV is a kind of different aircraft from common UAVs. It consists of parafoil canopy, payload and suspension lines and has the adventages of simple structure, low cost and high load weigh ratio, which is suitable for large-area and long-time surveillance and airdrop missions. This type of UAV has the problems of adding mass and flexible connection, and it is not easy to build the accurate model, which brings challenges to theoretical study and practical applications. This paper designs the structure of PPUAV and real-time data acquisition system, obtains flight data for modeling, identifies and validates the transfer functions using Matlab System Identification Toolbox. Finally the model of PPUAV is obtained, which gives a practicable method of PPUAV modeling and does a preliminary work for the following controller design and mission planning.\",\n \"Title: SSVEP-Based Brain-Computer Interface Controlled Functional Electrical Stimulation System for Upper Extremity Rehabilitation.\\nYear: 2016\\n\\nAbstract: Traditional rehabilitation techniques have limited effects on the recovery of patients with tetraplegia. A brain–computer interface (BCI) provides an interactive channel that does not depend on the normal output of peripheral nerves and muscles. In this paper, an integrated framework of a noninvasive electroencephalogram (EEG)-based BCI with a noninvasive functional electrical stimulation (FES) is established, which can potentially enable the upper limbs to achieve more effective motor rehabilitation. The EEG signals based on steady-state visual evoked potential are used in the BCI. Their frequency domain characteristics identified by the pattern recognition method are utilized to recognize intentions of five subjects with average accuracy of 73.9%. Furthermore the movement intentions are transformed into instructions to trigger FES, which is controlled with iterative learning control method, to stimulate the relevant muscles of upper limbs tracking desired velocity and position. It is a useful technology with potential to restore, reinforce or replace lost motor function of patients with neurological injuries. Experiments with five healthy subjects demonstrate the feasibility of BCI integrated with upper extremity FES toward improved function restoration for an individual with upper limb disabilities, especially for patients with tetraplegia.\",\n \"Title: Enhanced ICP for the Registration of Large-Scale 3D Environment Models: An Experimental Study.\\nYear: 2016\\n\\nAbstract: One of the main applications of mobile robots is the large-scale perception of the outdoor environment. One of the main challenges of this application is fusing environmental data obtained by multiple robots, especially heterogeneous robots. This paper proposes an enhanced iterative closest point (ICP) method for the fast and accurate registration of 3D environmental models. First, a hierarchical searching scheme is combined with the octree-based ICP algorithm. Second, an early-warning mechanism is used to perceive the local minimum problem. Third, a heuristic escape scheme based on sampled potential transformation vectors is used to avoid local minima and achieve optimal registration. Experiments involving one unmanned aerial vehicle and one unmanned surface vehicle were conducted to verify the proposed technique. The experimental results were compared with those of normal ICP registration algorithms to demonstrate the superior performance of the proposed method.\",\n \"Title: Active Model-Based Control for Pneumatic Artificial Muscle.\\nYear: 2017\\n\\nAbstract: In this paper, an active model-based control scheme is developed for the pneumatic artificial muscle (PAM), to compensate for the uncertainties in the dynamics model of the PAM. First, a simplified three-element model with respect to a specific range of pressure is formulated as the reference model. Second, a Kalman filter is adopted to actively estimate the errors involved in the reference model,...\",\n \"Title: Self-Healing Control Design under Actuator Fault Occurrence on Single-rotor Unmanned Helicopters.\\nYear: 2016\\n\\nAbstract: Actuator faults are inevitable but affect reliability and safety of unmanned helicopters (UHs), especially when there are actuator constraints. In this paper, self-healing control, which is an extended active fault-tolerant control (FTC) method with reference redesign on-line, is proposed to analyze and to guarantee the safety of single-rotor UHs (SUHs) under both actuator faults and constraints. The safety includes body safety and mission safety. More specifically, body safety represents the stability of SUH itself and mission safety represents mission accomplishment with acceptable performance, furthermore, set-point tracking mission is considered. The main contribution of this paper is to analyze and to guarantee the safety of SUHs by solving a set of Linear Matrix Inequalities (LMIs) at one time. The set of LMIs includes saturation compensator design and stability guaranty with a given controller in the absence of actuator constraints, actuator fault compensation analysis, reference reachability analysis and reference redesign. On the other hand, by adding swashplate configuration, SUH model with real actuator outputs as control inputs is constructed which can describe actuator faults more clearly compared to SUH models with nominal control inputs. Finally, the proposed self-healing control method is illustrated by simulation with a nonlinear SUH model.\",\n \"Title: Design and Analysis of a Mutual Inductance Coupling-Based Microdeformation Sensor.\\nYear: 2017\\n\\nAbstract: Mutual inductance coupling-based electromagnetic sensors utilize the quasi-static or dynamic magnetic excitation and sensing signals to detect the multiaxis deformation. The compact size and high sensitivity allow their application in tiny and precise measurement systems, such as space-confined minimally invasive surgery. Until now, however, there has not been any theoretical derivation of the rel...\",\n \"Title: Nonlinear Modeling for a Water-Jet Propulsion USV: An Experimental Study.\\nYear: 2017\\n\\nAbstract: Although unmanned surface vehicles (USVs) have been extensively researched and applied to many typical scenarios, high-performance autonomous control is still an open problem. One of their major problem stems from the difficulty in constructing a sufficient accurate and sufficient simple control-oriented dynamics model. Owing to the highly complicated physical mechanisms of hydrodynamics, USV syst...\",\n \"Title: Gpu-Based Heuristic Escape For Outdoo Large Scale Registration\\nYear: 2016\\n\\nAbstract: heterogeneous robot introduce a higher perception ability than single type robots in outdoor environments. One key problem is to making the 3D environmental model from the cooperated robots in real time, especially in the unstructured environment. Based on our previous work on outdoor environment registration method, in this paper, we introduce a CPU based Enhanced ICP method for large-scale heterogeneous robot registration. First, we combine the GPU-based nearest neighbor search in the traditional ICP framework. Second, we proposed a measurement and estimation model for the local minima problem. Third, we proposed a CPU-based heuristic escape method to generate the escaping transformation in real time. Experiments involving one unmanned aerial vehicle and one unmanned surface vehicle were conducted to verify the proposed technique. The experimental results were compared with those of normal ICP registration algorithms to demonstrate the performance of the proposed method.\",\n \"Title: Robust Tracking Of Dexterous Continuum Robots: Fusing Fbg Shape Sensing And Stereo Vision\\nYear: 2017\\n\\nAbstract: Robust and efficient tracking of continuum robots is important for improving patient safety during space-confined minimally invasive surgery, however, it has been a particularly challenging task for researchers. In this paper, we present a novel tracking scheme by fusing fiber Bragg grating (FBG) shape sensing and stereo vision to estimate the position of continuum robots. Previous visual tracking easily suffers from the lack of robustness and leads to failure, while the FBG shape sensor can only reconstruct the local shape with integral cumulative error. The proposed fusion is anticipated to compensate for their shortcomings and improve the tracking accuracy. To verify its effectiveness, the robots' centerline is recognized by morphology operation and reconstructed by stereo matching algorithm. The shape obtained by FBG sensor is transformed into distal tip position with respect to the camera coordinate system through previously calibrated registration matrices. An experimental platform was set up and repeated tracking experiments were carried out. The accuracy estimated by averaging the absolute positioning errors between shape sensing and stereo vision is 0.67 +/- 0.65 mm, 0.41 +/- 0.25 mm, 0.72 +/- 0.43 mm for x, y and z, respectively. Results indicate that the proposed fusion is feasible and can be used for closed-loop control of continuum robots.\",\n \"Title: A Novel Real-Time Gesture Recognition Algorithm For Human-Robot Interaction On The Uav\\nYear: 2017\\n\\nAbstract: This paper provides a new real-time gesture recognition technology for Unmanned Aerial Vehicle (UAV) Control. Despite of the tradition robot controlling system that uses the pre-defined program to control the UAV, this system allows the users to on-line design and control the UAV to finish the abrupt urgent task with different gestures. The system is composed of three parts: On-line personal feature training system, Gesture recognition system and UAV motion control system. In the first part, we collect and analyze user gestures, extract features data and train the recognition program in real time. In the second part, a multi-feature hierarchical filtering algorithm is applied to guarantee both the accuracy and real-time processing speed of our gesture recognition method. In the last part, the gesture recognition result is translated to a UAV through a data transmitter based on Mavlink protocol to achieve the human on-line control for the UAV. Through two extensive experiments, the effectiveness and efficiency of our method has been confirmed.\",\n \"Title: Artificial compound eye: a survey of the state-of-the-art.\\nYear: 2017\\n\\nAbstract: An artificial compound eye system is the bionic system of natural compound eyes with much wider field-of-view, better capacity to detect moving objects and higher sensitivity to light intensity than ordinary single-aperture eyes. In recent years, renewed attention has been paid to the artificial compound eyes, due to their better characteristics inheriting from insect compound eyes than ordinary optical imaging systems. This paper provides a comprehensive survey of the state-of-the-art work on artificial compound eyes. This review starts from natural compound eyes to artificial compound eyes including their system design, theoretical development and applications. The survey of artificial compound eyes is developed in terms of two main types: planar and curved artificial compound eyes. Finally, the most promising future research developments are highlighted.\",\n \"Title: Condition directed Multi-domain Adversarial Learning for Loop Closure Detection.\\nYear: 2017\\n\\nAbstract: Loop closure detection (LCD) is the key module in appearance based simultaneously localization and mapping (SLAM). However, in the real life, the appearance of visual inputs are usually affected by the illumination changes and texture changes under different weather conditions. Traditional methods in LCD usually rely on handcraft features, however, such methods are unable to capture the common descriptions under different weather conditions, such as rainy, foggy and sunny. Furthermore, traditional handcraft features could not capture the highly level understanding for the local scenes. In this paper, we proposed a novel condition directed multi-domain adversarial learning method, where we use the weather condition as the direction for feature inference. Based on the generative adversarial networks (GANs) and a classification networks, the proposed method could extract the high-level weather-invariant features directly from the raw data. The only labels required here are the weather condition of each visual input. Experiments are conducted in the GTAV game simulator, which could generated lifelike outdoor scenes under different weather conditions. The performance of LCD results shows that our method outperforms the state-of-arts significantly.\",\n \"Title: Towards Stable Adversarial Feature Learning for LiDAR based Loop Closure Detection.\\nYear: 2017\\n\\nAbstract: Stable feature extraction is the key for the Loop closure detection (LCD) task in the simultaneously localization and mapping (SLAM) framework. In our paper, the feature extraction is operated by using a generative adversarial networks (GANs) based unsupervised learning. GANs are powerful generative models, however, GANs based adversarial learning suffers from training instability. We find that the data-code joint distribution in the adversarial learning is a more complex manifold than in the original GANs. And the loss function that drive the attractive force between synthesis and target distributions is unable for efficient latent code learning for LCD task. To relieve this problem, we combines the original adversarial learning with an inner cycle restriction module and a side updating module. To our best knowledge, we are the first to extract the adversarial features from the light detection and ranging (LiDAR) based inputs, which is invariant to the changes caused by illumination and appearance as in the visual inputs. We use the KITTI odometry datasets to investigate the performance of our method. The extensive experiments results shows that, with the same LiDAR projection maps, the proposed features are more stable in training, and could significantly improve the robustness on viewpoints differences than other state-of-art methods.\",\n \"Title: An active fault-tolerant control framework against actuator stuck failures under input saturations\\nYear: 2017\\n\\nAbstract: AbstractAbstract In this paper, a control framework including active fault-tolerant control FTC and reference redesign is developed subject to actuator stuck failures under input saturations. FTC synthesis and reference redesign approaches are proposed to guarantee post-fault system safety and reference reachability. Then, these features are analyzed under both actuator stuck failures and constraints before fault-tolerant controller switches. As the main contribution, actuator stuck failures and constraints are unified so that they can be easily considered simultaneously. By means of transforming stuck failures into actuator constraints, the post-fault system can be regarded as an equivalent system with only asymmetrical actuator constraints. Thus, methods against actuator saturations can be used to guarantee regional stability and produce the stability region. Based on this region, stuck compensation is analyzed. Specifically, an unstable open-loop system is considered, which is more challenging. Furthermore, the method is extended to a set-point tracking problem where the reachability of the original reference can be evaluated. Then, a new optimal reference will be computed for the post-fault system if the original one is unreachable. Finally, simulation examples are shown to illustrate the theoretical results.\",\n \"Title: Synchronous Adversarial Feature Learning for LiDAR based Loop Closure Detection\\nYear: 2018\\n\\nAbstract: Loop C losure Detection (LCD) is the essential module in the simultaneous localization and mapping (SLAM) task. In the current appearance-based SLAM methods, the visual inputs are usually affected by illumination, appearance and viewpoints changes. Comparing to the visual inputs, with the active property, light detection and ranging (LiDAR) based point-cloud inputs are invariant to the illumination and appearance changes. In this paper, we extract 3D voxel maps and 2D top view maps from LiDAR inputs, and the former could capture the local geometry into a simplified 3D voxel format, the later could capture the local road structure into a 2D image format. However, the most challenge problem is to obtain efficient features from 3D and 2D maps to against the viewpoints difference. In this paper, we proposed a synchronous adversarial feature learning method for the LCD task, which could learn the higher level abstract features from different domains without any label data. To the best of our knowledge, this work is the first to extract multi-domain adversarial features for the LCD task in real time. To investigate the performance, we test the proposed method on the KITTI odometry dataset. The extensive experiments results show that, the proposed method could largely improve LCD accuracy even under huge viewpoints differences.\",\n \"Title: Vibration Control of a Flexible Robotic Arm by Wave Absorption Based on a Lumped Dynamic Model.\\nYear: 2016\\n\\nAbstract: A wave absorption control strategy is proposed to suppress vibration at the distal end of a flexible robotic arm while achieving accurate position control. It assumes the flexible arm with an actuator at one end and a load at the other, and interprets the arm's dynamics with a lumped model in terms of mechanical waves entering and leaving the arm at the actuator-arm interface. Control input to the actuator is thus resolved into two superposed waves, which the actuator launches and absorbs simultaneously. From the motion start-up, the launch wave is assigned to the actuator, to which the absorbing wave is added subsequently. The absorbing wave is computed with the delayed tip motion. It absorbs the vibratory energy within the arm, and prevents the wave returning from the arm tip from entering the control system again. The properties of the control scheme proposed are studied throughout. It works very well under uncertainty, and is stable and robust, for tip positioning and trajectory tracking control, as demonstrated in the numerical results.\",\n \"Title: An inter-subject model to reduce the calibration time for motion imagination-based brain-computer interface.\\nYear: 2019\\n\\nAbstract: A major factor blocking the practical application of brain-computer interfaces (BCI) is the long calibration time. To obtain enough training trials, participants must spend a long time in the calibration stage. In this paper, we propose a new framework to reduce the calibration time through knowledge transferred from the electroencephalogram (EEG) of other subjects. We trained the motor recognition model for the target subject using both the target's EEG signal and the EEG signals of other subjects. To reduce the individual variation of different datasets, we proposed two data mapping methods. These two methods separately diminished the variation caused by dissimilarities in the brain activation region and the strength of the brain activation in different subjects. After these data mapping stages, we adopted an ensemble method to aggregate the EEG signals from all subjects into a final model. We compared our method with other methods that reduce the calibration time. The results showed that our method achieves a satisfactory recognition accuracy using very few training trials (32 samples). Compared with existing methods using few training trials, our method achieved much greater accuracy. Graphical abstract The framework of the proposed method. The workflow of the framework have three steps: 1, process each subjects EEG signals according to the target subject's EEG signal. 2, generate models from each subjects' processed signals. 3, ensemble these models to a final model, the final model is a model for the target subject.\",\n \"Title: Contact Force Control Of An Aerial Manipulator In Pressing An Emergency Switch Process\\nYear: 2018\\n\\nAbstract: The dangerous work situation in industrial leakage accidents urgently needs a flexible and small robot to help workers perform operations and to protect them from being injured. An aerial manipulator system consisting of a hexa-rotor UAV and a one-DOF manipulator is developed, and is used to press an emergency switch to shut off machinery in an emergency. In practical application, an aerial manipulator usually performs contact operations as the UAV platform is in hover flight. The hovering UAV acting as a spring-mass-damper system is firstly proved. Then, based on the derived spring-mass-damper system model and the impedance control algorithm, the force-sensorless contact force control method is presented. That is, the force is indirectly controlled through controlling the UAV's position error and pitch angle simultaneously. The practical operation experiment of pressing an emergency button shows that the proposed method is able to control the contact force as the aerial manipulator interacts with the external environment.\",\n \"Title: Path-tracking control of bevel-tip needles using Model Predictive Control\\nYear: 2016\\n\\nAbstract: The bevel-tip flexible needle is an improvement of the clinical puncture needle and has the potential to reduce surgery traumas and improve puncture accuracy. Due to the nonholonomic kinematics model, it is difficult to drive flexible needles to track a pre-plan path. In this paper, we propose an effective path tracking control method based on Model Predictive Control (MPC). The kinematics model of flexible needles is described firstly, according to which the control method is designed. Then, the path tracking control method is presented in detail. The finite prediction horizon of MPC is extended to infinite in order to obtain a global optimal solution. Due to the nonlinear model, the objective function of receding horizon optimization is also nonlinear, and Particle Swarm Optimization (PSO) is employed to search optimal predictive control series. At last, simulations are conducted and results illustrate that the proposed controller performs well to precisely drive the flexible needle to track a desired path.\",\n \"Title: Separated adaptive control scheme of a rotor-flying manipulator\\nYear: 2016\\n\\nAbstract: Rotor flying manipulator (RFM), a new kind of mobile robot system being composed of a rotor flying robot (RFR) and a (several) manipulator(s), has absorbed great attentions in recent years because it enables a RFR to complete active tasks such as mastering and transporting objects. However, steady control of the RFM during both maneuvering and operating is of great difficulty due to the heavy force/moment coupling between the RFR and the manipulator, which introduce high nonlinearity and complexity to the system model. In this paper, a new control scheme of the RFM is proposed to ensure the steady flight. Firstly, the nonlinear mathematical model is derived, which is followed by the coupling analysis to show how the movement of the manipulator influences the whole system's behavior. Subsequently, based on these analyses, a new control scheme is designed with obtainable coupling force/moment. The basic idea of the controller is to take the coupling as a disturbance and separately control the RFR and the manipulator, and the stability is ensured to properly design the controller parameters. Finally, simulations are conducted and the results show the feasibility and validity of the proposed controller.\",\n \"Title: Natural Growth-Inspired Distributed Self-Reconfiguration of UBot Robots.\\nYear: 2019\\n\\nAbstract: The decentralized self-reconfiguration of modular robots has been a challenging problem. This work proposed a biological method inspired by the plant growth for the distributed self-reconfiguration of UBot systems. L-systems are implemented to construct target topology, and turtle interpretation is extended to lead the self-reconfiguration process. Parametric reproduction rules introduce the external influence to the reconfiguration process by distributed modules' local sensing. Each module can move independently to change relative positions, and robotic structures develop in the natural growth style. This leads to a convergent and environmentally sensitive control method for the distributed self-reconfiguration. Reconfiguration processes can converge to desired configuration and are scalable to module numbers by reproducing predefined substructures in principle. The overall performance of the proposed strategy is evaluated with simulations and 11 experiments. Simulation and experimental results turn out to be convergent and environmentally sensitive.\",\n \"Title: Active modeling for pneumatic artificial muscle\\nYear: 2016\\n\\nAbstract: In this paper, an active modeling approach for a pneumatic artificial muscle (PAM) is being considered. The PAM's nonlinearity, hysteresis and time-varying characteristics cause difficulties in modeling its behavior and designing high-performance controllers. Here, a generalized three-element model of a PAM is proposed to obtain the reference model in the reference mode (in a given small pressure range). The equivalent state space representation of the reference model is obtained by applying the linearization approach. The model error is introduced to the equivalent state space model, and the joint estimation is adopted to estimate the system state and the model error simultaneously. Experimental studies are conducted to demonstrate the existence of the model error, and verify the necessity of introducing the model error to the reference model, and evaluate the effect of the proposed active modeling approach in changing modes (not in the given pressure range).\",\n \"Title: Mechanical Design And Control Method Of A Hollow Modular Joint For Minimally Invasive Spinal Surgery\\nYear: 2018\\n\\nAbstract: Design of the hollow modular joint plays an important role in modern robot layout, fixation, and wiring. In this paper, a hollow modular joint that meets the requirement of a minimally invasive surgical robot is proposed. The mechanical and control design is sequentially illustrated, and the torque sensor and its optimization are provided. Furthermore, a free-force control method is introduced. To analyze the designed module, the simulation of the redundant robot, comprised of the designed joint in seven degrees of freedom, is presented. The results of analyses showed that the designed hollow modular joint is valid and effective.\",\n \"Title: Closed-loop control of bevel-tip needles based on path planning.\\nYear: 2018\\n\\nAbstract: Bevel-tip needles have the potential to improve paracentetic precision and decrease paracentetic traumas. In order to drive bevel-tip needles precisely with the constrains of path length and path dangerousness, we propose a closed-loop control method that only requires the position of the needle tip and can be easily applied in a clinical setting. The control method is based on the path planning method proposed in this paper. To establish the closed-loop control method, a kinematic model of bevel-tip needles is first presented, and the relationship between the puncture path and controlled variables is established. Second, we transform the path planning method into a multi-objective optimization problem, which takes the path error, path length and path dangerousness into account. Multi-objective particle swarm optimization is employed to solve the optimization problem. Then, a control method based on path planning is presented. The current needle tip attitude is essential to plan an insertion path. We analyze two methods to obtain the tip attitude and compare their effects using both simulations and experiments. In the end, simulations and experiments in phantom tissue are executed and analyzed, the results show that our methods have high accuracy and have the ability to deal with the model parameter uncertainty.\",\n \"Title: Kf-Based Active Modeling For A Quadrotor Slung Load System\\nYear: 2018\\n\\nAbstract: The control of quadrotor slung load (QSL) systems is a challenging task as a result of some distinguishing features like the multiple nonlinearities and time-varying load swing. To design an effective control scheme, the top priority is to establish an excellent model. In this paper, a practical active modeling method based on the Kalman Filter (KF) for a QSL system is developed to compensate uncertainties in system dynamics. First, a simplified quadrotor model is formulated as the reference model. Second, modeling errors are introduced and the KF is adopted to actively estimate the errors involved in the reference model. Finally, some experiments are conducted to validate the remarkable performance of the proposed modeling strategy in terms of uncertainties as well as disturbances in the dynamic model.\",\n \"Title: Force Feedback Control of a Robotic Needle Insertion into Layered Soft Tissues\\nYear: 2018\\n\\nAbstract: In this study, a feedback control law is proposed to steer a robotic needle using force information from a fiber optic sensor. This sensor is integrated into the lumen at the distal end of the needle to measure the needle insertion force. The force signals are analyzed via wavelet transform to identify the boundaries of layered soft tissues in real time. The boundaries information is then used in the robotic needle steering scheme to reduce as much as possible the insertion force, and mitigate the risk of tissue injury. Porcine belly tissue phantoms are herein used in the ex vivo tests of robotic needle insertion, and comparative study has been done with and without insertion force feedback. Experimental results show that the force feedback control approach proposed reduces effectively the insertion force.\",\n \"Title: Path Planning of UGV Based on Bézier Curves\\nYear: 2019\\n\\nAbstract: An effective path planner is critical for autonomous traversal of unmanned ground vehicles (UGVs) in harsh environments. This paper describes a novel path planning method considering Bezier curves and a two-layer planning framework. In the two-layer framework, a road centerline (RCL) estimator located on the upper layer works as a global planner to obtain the local target for the bottom local planner. The RCL is estimated from a series of candidate Bezier curves based on a safety criterion. In the bottom layer, an optimal trajectory planner and a speed planner make up the local planner to obtain the desired steering turning angle and linear speed. The criteria for optimal trajectory selection are designed for comfortable driving. Road safety is considered in the speed planner for robust driving. Three sets of simulations are used to evaluate and quantify the relative performance of variations of our path planning algorithm. The proposed path planning method is implemented on a modified Polaris RZR 800 UGV, too. Two experiments based on this UGV are set up in the country road environment to demonstrate the viability of the proposed method.\",\n \"Title: A novel ESMF-based observer and control scheme for a type of tendon-sheath hysteresis system\\nYear: 2021\\n\\nAbstract: Due to the backlash hysteresis, robust and accurate tracking control of a hysteresis system is a challenging problem. We propose in this paper an active observer based robust control scheme to reject the influence of hysteresis. Firstly, the normal piecewise C–H model of hysteresis plant was modified into a continuous form so that an active observer could be applied on. Secondly, an observer was designed based on the extended set-membership filter (ESMF). This intends to take the advantages of ESMF on the bound-guaranteed estimation and the unknown but bounded (UBB) noise tolerance. Thirdly, a robust controller was constructed using both the magnitude and the bounds of the hysteresis uncertainty estimated by the observer. The stability of the control scheme was theoretically proved. Experiments were conducted on a robotic flexible ureteroscope test-bed. The performance of the modified model, the ESMF-based observer, and the robust control were extensively verified, and the improvements benefited from this proposed scheme were demonstrated.\",\n \"Title: A BAS-Based Strategy for Redundant Manipulator Tracking Continuous Moving Object in 3D Relative Velocity Coordinate\\nYear: 2021\\n\\nAbstract: The ability of real-time tracking of manipulator end-effect is critical for intelligent manipulators. This paper presents a control strategy for tracking the continuous moving object. Our research aims at converting the problem of tracking moving object to a planning problem of relative velocity vector by establishing Relative Velocity Coordinate (RVC) on manipulator end-effect. The key novelty of the proposed strategy about constructing the optimization problem lies in considering both relative velocity and relative position simultaneously. The Beetle Antennae Search (BAS) algorithm is introduced to tackle the formulated optimization function. Theory analysis and different simulation experiments are provided to illustrate the feasibility and efficiency of the proposed control strategy.\",\n \"Title: Design and Development of a Portable Electrical Impedance Tomography System\\nYear: 2021\\n\\nAbstract: Electrical impedance tomography (EIT) is a non-invasive detection technique for human tissue imaging. However, most of the current EIT systems are complex and expensive in design. In this paper, we have developed a portable and economic EIT system, which just consists of five parts, including a data acquisition card (DAQ), a power module, a signal generator, a voltage-controlled current source, and a multiplexer module. The fast Fourier transform is used to extract the amplitude of the voltage signals collected by the DAQ. The Tikhonov regularization algorithm is adopted to reconstruct the image of conductivity distribution. Experiments on a practical phantom were designed and conducted to validate the performance of the system. The results showed that the developed system has an average signal-to-noise ratio of 65 dB for measurement channels and a high imaging signal accuracy of 0.99. The conductivity distribution in the phantom was successfully reconstructed by the developed EIT system.\",\n \"Title: Continuous Estimation of Knee Angles from Decomposition of Single Channel Surface Electromyography Signals\\nYear: 2021\\n\\nAbstract: Multiple surface electromyography (sEMG) channels used in motion estimation would increase implementation complexity. However, reduced sEMG channels would lead to insufficient information and deteriorate the estimation performance. This paper studies the problem of motion estimation based on single-channel sEMG signals by combining a decomposition method into a state-space model. More precisely, t...\",\n \"Title: Active Modeling and Control for Manipulators\\nYear: 2021\\n\\nAbstract: In this paper, an active model-based control scheme is proposed for the manipulators with parameter uncertainties and disturbances. Firstly the Euler-Lagrange dynamic model of n-link manipulator is linearized by Lie derivation. Then Kalman Filter is utilized to estimate the model error in real-time. Moreover, an active model enhanced state feedback controller is proposed based on the estimated mod...\",\n \"Title: Modeling and Robust Adaptive Control for Tendon-Driven with Bending Tip Systems\\nYear: 2021\\n\\nAbstract: Tendon-driven with bending tip (TDBT) mechanisms were extensively applied in the field of surgery and rescue robotics. TDBT has exposed many complicated characteristics, such as complex hysteresis, motion backlash and rate-dependent behavior, etc., which bring great challenges to the modeling and control subject of the bending angle. In this research, the TDBT's dynamics model was established with...\",\n \"Title: Preliminary Design and Performance Test of an Origami Actuator Inspired by Yoshimura Pattern\\nYear: 2021\\n\\nAbstract: Origami has been inspiring roboticists to create new devices. Here, we present a preliminary design and performance test of a novel origami actuator inspired by Yoshimura pattern. This actuator is in a hexagonal configuration made of a single piece of paper. Driven by the threads, the origami actuator can bend and shorten. The design of its folding pattern is presented, and the folding procedure i...\",\n \"Title: Active Model-Based Hysteresis Compensation and Tracking Control of Pneumatic Artificial Muscle\\nYear: 2022\\n\\nAbstract: The hysteretic nonlinearity of pneumatic artificial muscle (PAM) is the main factor that degrades its tracking accuracy. This paper proposes an efficient hysteresis compensation method based on the active modeling control (AMC). Firstly, the Bouc-Wen model is adopted as the reference model to describe the hysteresis of the PAM. Secondly, the modeling errors are introduced into the reference model, and the unscented Kalman filter is used to estimate the state of the system and the modeling errors. Finally, a hysteresis compensation strategy is designed based on AMC. The compensation performances of the nominal controller with without AMC were experimentally tested on a PAM. The experimental results show that the proposed controller is more robust when tracking different types of trajectories. In the transient, both the overshoot and oscillation can be successfully attenuated, and fast convergence is achieved. In the steady-state, the proposed controller is more robust against external disturbances and measurement noise. The proposed controller is effective and robust in hysteresis compensation, thus improving the tracking performance of the PAM.\",\n \"Title: Active Modeling Based Control for Aerial Manipulator Systems\\nYear: 2021\\n\\nAbstract: Expanding an unmanned aerial vehicle (UAV) with an equipped robotic arm increases the ability of the UAV to actively interact with the environment. During the process of active tasks, precise motion control under model uncertainties and external disturbances is a challenging issue. To solve this issue, an active modeling based control scheme is proposed in this paper. In this scheme, the aerial manipulator system (AMS) is modeled with consideration of various uncertainties represented by the model error and the process noise. The model error caused by the gravity and movement of the manipulator is estimated by the unscented kalman filter (UKF). The estimation is further integrated into a nominal controller to achieve high-precision motion control. Detailed experimental results on the self-bulit testbed illustrate the effectiveness and good performance of the proposed method.\",\n \"Title: Plantar pressure-based temporal analysis of gait disturbance in idiopathic normal pressure hydrocephalus: Indications from a pilot longitudinal study\\nYear: 2022\\n\\nAbstract: Background and Objective: Idiopathic normal pressure hydrocephalus (iNPH) is a common yet poten-tially reversible neurodegenerative disease, and gait disturbance is a major symptom. Lots of methodolog-ical and clinical work has been conducted on gait disturbance analysis for differential diagnosis, presur-gical test, and postsurgery assessment of iNPH. Nevertheless, the verification analysis was mostly lacking for surgery response, and the temporal characteristics of ground reaction force has been rarely investi-gated.Methods: In this work, we propose that plantar pressure features fundamentally signifies iNPH gait dis-turbance and improvement after cerebrospinal fluid (CSF) drainage by lumbar puncture tap test as well as surgical shunt implantation. The plantar pressure signals of six iNPH patients and eight healthy controls were collected, and an online database of sixteen healthy controls were used. For patients, data were collected in five periods, which are the baseline before the tap test, 8, 24, and 72 hours after the tap test, and one month after the shunt implantation surgery, respectively. Fast dynamic time warping (DTW) with an improved DTW barycenter averaging (DBA) method was proposed for temporal analysis with the measured and online plantar pressure data. An plantar-pressure variation index (PPVI) was formulated to characterize the temporal dynamic stability of walking.Results: The PPVI based on temporal analysis of plantar pressure well discriminated the impaired gait (baseline, 24 and 72 hours after tap test) with the improved gait (8 hours after tap test and follow up after surgery) of the patients. Further, the PPVI was close for the improved gait of the patients and the healthy gait measured in our study as well as in the online database.Conclusions: Plantar pressure-based temporal features are promisingly effective for clinical examination and treatment of iNPH. (c) 2022 Elsevier B.V. All rights reserved.\",\n \"Title: Simultaneous Calibration of the Hand-Eye, Flange-Tool and Robot-Robot Relationship in Dual-Robot Collaboration Systems\\nYear: 2022\\n\\nAbstract: A multi-robot collaboration system can complete more complex tasks than a single robot system. Ensuring the calibration accuracy between robots in the system is a prerequisite for the effective inter-robot cooperation. This paper presents a dual-robot system for orthopedic surgeries, where the relationships between hand-eye, flange-tool, and robot-robot need to be calibrated. This calibration problem can be summarized to the solution of the matrix equation of AXB=YCZ. A combined solution is proposed to solve the unknown parameters in the equation of AXB=YCZ, which consists of the dual quaternion closed-form method and the iterative method based on Levenberg-Marquardt (LM) algorithm. The closed-form method is used to quickly obtain the initial value for the iterative method so as to increase the convergence speed and calibration accuracy of the iterative method. Simulation and experimental analyses are carried out to verify the accuracy and effectiveness of the proposed method.\",\n \"Title: A supervised independent component analysis algorithm for motion imagery-based brain computer interface\\nYear: 2022\\n\\nAbstract: Recognizing the corresponding neural activities of independent components(ICs) obtained by independent component analysis(ICA) is of prime importance to take use of ICA in EEG analysis. There are many methods trying to solve this problem. But most of them combining ICA, a unsupervised method, and recognition of ICs in a separate way. In this paper, we propose a supervised method to extract the independent components corresponding to different motion imagery(MI) activities in the brain. By designing a new optimization objective and solving it, we combine the idea of ICA with principle of MI in an individual algorithm. From the perspective of event-related desynchronization and synchronization (ERD/ERS), specific frequency band power of the motion-related component should be enhanced or suppressed when executing or imaging movement of body. Therefore, the new optimization function extract the components that satisfy both independence and band power maximization for specific motions. Then, we solve this optimization problem based on the fixed-point iteration scheme. In the experimental stages, we show that our methods can extract motion-related independent components without losing independence. Experimental results show that, although basing on the principle of ERD/ERS, our methods’ effectiveness can be verified in the perspective of movement-related potential (MRP). Additionally, by identifying features in the extracted motion-related independent components, we can achieve better motion recognition accuracy. When using the proposed algorithms with different schema, the results yielded significant accuracy imporvements of 6.9%(p < 0.001) and 7.9%(p < 0.01).\",\n \"Title: Incremental Learning Framework for Autonomous Robots Based on Q-Learning and the Adaptive Kernel Linear Model\\nYear: 2022\\n\\nAbstract: The performance of autonomous robots in varying environments needs to be improved. For such incremental improvement, here we propose an incremental learning framework based on $Q$ -learning and the adaptive kernel linear (AKL) model. The AKL model is used for storing behavioral policies that are learned by <te...\",\n \"Title: Direct Inverse Hysteresis Compensation of Piezoelectric Actuators Using Adaptive Kalman Filter\\nYear: 2022\\n\\nAbstract: The hysteresis of the piezoelectric actuator exhibits obvious rate dependence, especially in fast scanning or tracking. This article proposes an adaptive hysteresis compensation method that integrates the direct inverse modeling (DIM) method and an adaptive Kalman filter (AKF). DIM is adopted to directly obtain the inverse hysteresis model and use it as the hysteresis compensator. AKF is utilized ...\",\n \"Title: Unmanned Aerial Transportation System With Flexible Connection Between the Quadrotor and the Payload: Modeling, Controller Design, and Experimental Validation\\nYear: 2023\\n\\nAbstract: Aerial delivery is becoming a reality due to the development of microelectronics and communication technology. Most existing methods for cable-suspended transportation systems utilize fixed-length cable to connect the unmanned aerial vehicle quadrotor and the payload. Such aerial transportation systems present underactuated property, which is caused by the indirectly controllable payload motion and the underactuation of the quadrotor itself. In practical applications, payload hoisting and lowering motion independent of the quadrotor altitude will further expand the application scope in such areas as limited space crossing and offshore sample collection. To realize the aforementioned objectives, a flexible connection between the quadrotor and the payload is realized by mounting an actuator beneath the fuselage. Suffering from strong nonlinearity and complex dynamic coupling, the control problem becomes extremely challenging and more cumbersome, as the system’s degree of freedom (DOF) increases. To deal with these problems, in this article, a nonlinear control approach is presented by energy-based analysis, which achieves simultaneous quadrotor positioning, payload swing elimination and hoisting\\n<bold xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">/</b>\\nlowering. Lyapunov techniques and LaSalle’s Invariance theorem are utilized to prove the asymptotic convergence of the equilibrium point. Finally, a series of hardware experiments are conducted on a self-built aerial transportation platform. As far as we know, this article provides the first mechanism and control solution for payload hoisting/lowering independent of the quadrotor altitude.\",\n \"Title: fNIRS Feature Extraction and Classification in Grip-Force Tasks\\nYear: 2021\\n\\nAbstract: It has been of increasing interest to decode the movements based on the changes in hemoglobin concentration in the cerebral cortex that can be measured by functional near-infrared spectroscopy (fNIRS). Existing work were mainly focused on motor imagery tasks for the advantages of fNIRS on cognitive activation detection, and motor tasks were not well studied. This paper investigated fNIRS feature e...\",\n \"Title: An sEMG-based Hill-type Model for Estimation of Swallowing Motion\\nYear: 2021\\n\\nAbstract: Dysphagia is a common clinical symptom which can cause dehydration, malnutrition, pneumonia, and even death. Surface electromyography (sEMG) signals, which can be obtained in a non-invasive way, have been used for screening dysphagia, and estimation of the swallowing motion based on the sEMG signals is essential. In this paper, we propose an sEMG-based Hill-type model for estimation of swallowing ...\",\n \"Title: An hFFNN-LM Based Real-Time and High Precision Magnet Localization Method\\nYear: 2022\\n\\nAbstract: Magnet tracking is an emerging tracking method for medical instruments and biological tissues, such as endoscopes and catheters. Traditional magnet tracking technology typically uses an optimization algorithm or heuristic algorithm to estimate the pose of a permanent magnet according to the measured magnetic induction intensity. However, this technology is limited by the high delay and the poor quality of the initial solution. This article proposes a new magnetic localization method, i.e., a hybrid feedforward neural network and Levenberg-Marquardt (hFFNN-LM) algorithm. FFNN provides an adjusted initial solution to the LM algorithm for solving the nonlinear inverse magnetic problem. The hFFNN-LM algorithm is promising for real-time magnetic tracking as it provides satisfactory tolerance for initially estimated parameters and fast search speed. The average single localization time is 1.07 ms. The experimental results show that the proposed method has a very low tracking delay compared to some other popular LM-based methods. The proposed hFFNN-LM algorithm achieves superior localization performances, i.e., the mean position and orientation errors are tested to be 0.70 mm and 0.90 degrees, respectively.\",\n \"Title: A non-contact system for intraoperative quantitative assessment of bradykinesia in deep brain stimulation surgery\\nYear: 2022\\n\\nAbstract: •A compact optical sensor measures patient voluntary movement without interfering.•A software monitors, analyzes and displays the movement and bradykinesia features.•The system was technically validated, and applied for 20 patients in DBS surgery.•This brings an effective solution for DBS intraoperative assessment of bradykinesia.\",\n \"Title: Active model-based nonlinear system identification of quad tilt-rotor UAV with flight experiments\\nYear: 2022\\n\\nAbstract: To propose an accurate and less complex model of a special unmanned aerial vehicle (UAV), namely tilt-rotor UAV (TRUAV), this study identifies the active model-based nonlinear system of a quad-TRUAV. First, a nominal nonlinear model of the vehicle is formulated. Some unstructured nonlinearities are ignored to reduce the complexity of the model. Then, due to the unstable dynamics of the open-loop system, the format of this nominal model is considered to design an innovative smooth-switch attitude control via interconnection and damping assignment passivity-based control (IDA-PBC). Active model-based nonlinear system identification is studied for the vehicle with the designed control method and flight experiments. The model error vector is defined and estimated by the unscented Kalman filter (UKF) to improve the accuracy of the model. The main contribution of this paper is to identify the nominal nonlinear model and to develop an active model method of the quad-TRUAV. The attitude control method with an innovative smooth-switch structure is another contribution to flight experiments. Numerical results are displayed to present the experimental results and effectiveness of the proposed nonlinear models.\",\n \"Title: Modeling and Robust Control for Tendon–Sheath Artificial Muscle System <italic/>Twist<italic/> With Time-Varying Parameters and Input Constraints: An Exploratory Research\\nYear: 2023\\n\\nAbstract: Tendon–sheath artificial muscle (TSAM) is a type of artificial muscle, which is widely used in robotic flexible endoscopies. The characteristics of the tendon force/position transmission were studied recently, but the control issue of the TSAM \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"/>\\ntwist\\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"/>\\n is still barely concerned. In this article, an effective robust control scheme is proposed for the TSAM \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"/>\\ntwist\\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"/>\\n, which achieves satisfactory tracking performance. First, a rigorous model was developed for the TSAM \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"/>\\ntwist\\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"/>\\n with consideration of parameters uncertainty and actuator input constraints, moreover, the disturbance of the discontinuous friction (Coulomb friction) was analyzed. Next, by applying some signal operation methods, a nonlinear robust controller was designed. In addition, the stability of the control strategy was proven theoretically by utilizing Lyapunov-based theory. Finally, a series of hardware experiments were conducted on a robotic flexible ureteroscope test-bed. The feasibility of the proposed model, the effectiveness and robustness of the designed control method were extensively validated.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":134,"string":"134"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":251,"string":"251"}}},{"rowIdx":252,"cells":{"question_id":{"kind":"string","value":"Houda Labiod"},"question":{"kind":"string","value":"Generate an abstract for the title \"VOPP: A VANET offloading potential prediction model.\" using the following items: 1. Intelligent Transportation Systems \n2. Cellular traffic offloading \n3. Vehicular Network (VANET) \n4. Optimization problem formulation \n5. Data offloading fraction."},"answer":{"kind":"string","value":"In this work, we investigate upon the potential of considering the Intelligent Transportation Systems (ITS) for cellular traffic offloading as an alternative to Wi-Fi and femtoCells approaches. We propose an analytical study based on an optimization problem formulation called VOPP where the objective is to elect the maximum number of data flows that could be routed to the downloaders through the Vehicular Network (VANET). VOPP considers the link availability between the infrastructure and the downloader, the medium contention, interferences, data volume, gateways capacity and the channel aggregation to evaluate the VANET capacity to support additional traffics. Numerical results of our analytical approach show that the data offloading fraction is closely tied to the data volume of the flows and to the vehicles positions and VANET topology."},"correct_answer":{"kind":"string","value":"In this work, we investigate upon the potential of considering the Intelligent Transportation Systems (ITS) for cellular traffic offloading as an alternative to Wi-Fi and femtoCells approaches. We propose an analytical study based on an optimization problem formulation called VOPP where the objective is to elect the maximum number of data flows that could be routed to the downloaders through the Vehicular Network (VANET). VOPP considers the link availability between the infrastructure and the downloader, the medium contention, interferences, data volume, gateways capacity and the channel aggregation to evaluate the VANET capacity to support additional traffics. Numerical results of our analytical approach show that the data offloading fraction is closely tied to the data volume of the flows and to the vehicles positions and VANET topology."},"documents":{"kind":"list like","value":["Title: A Performance Comparison of Position-Based Routing Approaches for Mobile Ad Hoc Networks\nYear: 2007\n\nAbstract: In this work we present a performance comparison study between SIFT (Simple Forwarding over Trajectory), an innovative and scalable trajectory-based approach, and DREAM (Distance Routing Effect Algorithm for Mobility), a stable, largely tested position-based scheme. In the literature, the latest studies indicate that control overhead is the most important drawback that routing protocols must face. Classical ad hoc routing schemes do not perform well in MANETS (Mobile Ad hoc Networks) because they were not designed to handle efficiently mobility handicaps. Position-based forwarding techniques perform better in highly dynamic scenarios, reducing control overhead consequences, but there may be some highly dynamic scenarios where they do not perform efficiently. Trajectory-based forwarding protocols solve the overhead problem and, thus, they perform efficiently in MANETS. Our study demonstrates that SIFT performs better than DREAM concerning delivery ratio, control overhead and route length in terms of number of hops. Its main handicap could be, a priori, the delivery delay. However, even if delay may be high in SIFT, control overhead may also causes even higher delivery delay in DREAM.","Title: A Layer-2 Multi-Hop Authentication and Credential Delivery Scheme for Vehicular Networks\nYear: 2008\n\nAbstract: In this paper we introduce a novel security architecture and security mechanisms for vehicular networks environments. Our approach provides a layer-2 multi-hop authentication and credential delivery scheme between vehicles and the network operator authentication server. We analyze the performance of the proposed solution through extensive simulations, showing the success of our scheme (compared to the legacy single-hop scheme) in providing a robust and efficient authentication and credential delivery to vehicles. Based on the obtained performance analysis, we derive some guidelines aiming to optimize our solution under various vehicles densities.","Title: Exploiting power-law node degree distribution in Chord overlays\nYear: 2009\n\nAbstract: In this paper, we propose to extend the topology of Chord to a bidirectional graph to provide a super-peer based lookup algorithm and a scalable broadcast search support. We consider routing algorithms for a bidirectional variant of Chord network and show how the resulting structure extends the search region and provides an efficient resource lookup service at a very little additional cost.","Title: A Distributed Hybrid Channel Selection and Routing Technique for Wireless Sensor Networks.\nYear: 2011\n\nAbstract: In this paper, we propose Well-Connected Dominating Set Channel Assignment (WCDS - CA), a distributed hybrid algorithm that uses a well-connected dominating set to perform a selection of communication channels in wireless sensor networks in such a way that the number of channels used and interference among sensor nodes remains minimal. Since the network topology allows each sensor node to be equipped with several radio interfaces, a set of parents and leaves are statically assigned to a single fixed channel. The routers are assigned to several orthogonal channels using the corresponding radio interfaces in such a way that they can switch dynamically to the static channels of parent nodes in order to minimize network interference. The tree based on Breadth-First Search is built out from the sink, with the result that the shortest between each sensor and the sink is established. This allows the data to be efficiently propagated from parent to router to parent towards the sink in order to reduce the number of individual transmissions. We compare the results obtained with those for a single channel by taking the common links used by each node on each channel and packets transmitted as performance criteria, and show that our proposal gives better results in dense wireless sensor networks.","Title: A New Access Control Solution for a Multi-Provider Wireless Environment\nYear: 2005\n\nAbstract: The fundamental goal in future 4G mobile multi-service networks is to provide an efficient mobile computing environment. We presume that future terminals will be equipped with multiple heterogeneous wireless interfaces. We want to enable each user to seamlessly move between different providers' networks. Besides seamless roaming, a key consideration is also devoted to quality-of-service provision. In this article, we propose a model and an architectural framework for supporting quality of service in the context of interconnected multi-provider wireless systems. The proposed integrated COPS-based management and RADIUS-based access control architecture will allow providers to offer multimedia services while optimizing the use of the underlying network resources. We suggest new concepts and protocols to provide solutions to these challenges and describe the French national research project named MMQoS aiming on building such future networks.","Title: Exploiting routing unfairness in DHT overlays\nYear: 2009\n\nAbstract: Peer-to-Peer overlays have become a popular paradigm for building distributed systems, aiming to provide resource localization and sharing in large-scale networks. To design an overlay network, the first step is to choose an overlay topology connecting all the overlay nodes. Many proposed distributed hash table schemes for peer-to-peer network are based on some traditional calculated interconnection topologies. In this paper, we propose to extend the DHT topology to a bidirectional graph to provide a super-peer based lookup algorithm and a scalable resource localization support. We consider bidirectional routing algorithms and show how the resulting unfair routing structure extends the search region and provides an efficient resource lookup service at a very little additional cost.","Title: Performance Comparison Of Multipath Reactive Ad Hoc Routing Protocols\nYear: 2008\n\nAbstract: The recent proliferation of wireless devices extends the scope of Mobile Ad hoc NETworks (MANETs) applications beyond the military domain to include civil and commercial application scenarios. Since MANETs are composed of mobile terminals with limited resources, guaranteeing their security remains an unsolved and motivating challenge. Due to advantageous features like infrastructureless and spontaneous deployment, MANETs offer an opportunity to set up temporary, dynamic and local networks for low cost. However, some of their characteristics like unreliability of wireless links, dynamic topology, and absence of underlying infrastructure raise serious problems which become critical when security is also considered. Multipath routing scheme enhances the robustness of routing protocols and offers a mean to mitigate networks mobility impact and node misbehaviors. In this paper we compare the performances of five multipath routing protocols: three node-disjoint multipath routing protocols and two routing protocols based on a Untrusted Node Disjoint (UND) path scheme. Comparisons between these protocols highlight the improvements raised by the UND scheme under different attack configurations.","Title: A performance comparison of multicast routing protocols in ad hoc networks.\nYear: 2003\n\nAbstract: Multicast Routing in Mobile Ad hoc NETworks (MANETs) is a recent research topic. In this paper, we present a performance study of three multicast protocols: ODMRP, ADMR, and SRMP. Source Routing-based Multicast Protocol (SRMP) is a new on-demand multicast routing protocol that applies a source routing mechanism and constructs a mesh to connect group members. The strength of SRMP lies on its nodes selection criteria during mesh construction. Instead of using the shortest path as most of the other protocols, SRMP provides paths in terms of connectivity strength, higher battery life, and links' availability. A performance comparison with ODMRP and ADMR shows that SRMP provides better route lifetime and battery lifetime.","Title: Hybrid architecture for resource reservation in IP based mobile networks\nYear: 2010\n\nAbstract: User mobility management is one of the important components of mobile multimedia systems. In an IP-based mobility case, a mobile node should be able to seamlessly obtain reserved resources after handover to a new access router. This is essential for both service continuity and quality of service assurance. In this paper, we introduce a hybrid architecture which allows a mobile node to seamlessly obtain reserved resources from its new location (seamless reservation), as well as to quickly release obsolete resources along the old path. In this architecture, reservation on access networks is performed by using path-decoupled approach, while path-coupled approach is used on backbone networks. Moreover, instead of using sender-initiated or receiver-initiated approach, mobile-node-initiated approach is used in this architecture to further improve reservation performance. In our performance analysis, we analyze advance reservation delay and release delay, as well as reservation underutilization.","Title: Adaptive path energy conserving routing in MANETs\nYear: 2005\n\nAbstract: The specific features of mobile ad hoc networks (MANETs) impose new requirements for routing protocols. The aim of this paper is to present an approach that enhances routing performance by integrating ad hoc related characteristics. We propose a loop-free adaptive path energy conserving scheme which attempts to minimize both routing and storage overhead in order to efficiently provide robustness to host mobility, adaptability to wireless channel fluctuations and optimization of network resources use in large-scale networks. The strength of our scheme, based on source routing approach, named Energy Conserving Dynamic Source Routing (EC-DSR), is to handle network state related constraints such as node's energy consumption, links' availability and paths' quality. The performance of the proposed scheme is evaluated via simulation and is compared to DSR protocol. Better results are obtained with EC-DSR in terms of control overhead. Furthermore, EC-DSR shows significant improvements in delay and forwarding efficiency for large scalable networks.","Title: Prioritizing and Enhancing Vehicular Networks Authentication Process Using DSRC Channels Diversity\nYear: 2008\n\nAbstract: In this paper we introduce a prioritization scheme for enhancing the performance of the authentication process in vehicular networks using Dedicated Short Range Communications (DSRC). We consider the authentication as a service that should be required by each user in order to gain access to the network and to the offered services. Instead of using a unique channel to transmit the messages of the authentication service as in the case of the legacy DSRC model, our scheme extends this latter through exploiting the various DSRC channels based on a channel sensing approach that aims to prioritize the transmission of the authentication messages (with respect to the transmission of other DSRC services messages of the same priority as the authentication service). We implemented our proposed solution under the GrooveNet vehicular network simulator, where we analyze its performance impact on a previously proposed vehicular network authentication mechanism. Extensive simulations show the success of our proposed scheme in providing a more efficient and robust authentication in the presence of other services' traffics.","Title: Resaco: An Open And Programmable Multi-Domain Platform For Cooperative And Auto-Configurable Networks\nYear: 2004\n\nAbstract: This paper presents a set of studies and proposals related to cooperative, auto-configurable and adaptive networks. It summarizes some extensions and experiments performed within the RESACO project. The objective of this project is to propose viable architectures and tools that enable and enhance Quality-of-Service (QoS), mobility, service discovery and security aspects over multidomain and heterogeneous networks. The proposed extensions are based on the use of programmable software-based edge routers and access points. Additional features that enable are adaptability, auto-configuration and cooperation are experimented.","Title: Mobility And Qos Of 802.11 And 802.11e Wireless Lan Standards\nYear: 2009\n\nAbstract: Quality of service is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN are the most widely used WLAN standards today, and the IEEE 802.11e quality of service enhancement standard exists and introduces quality of service support for multimedia applications. This paper compares the propositions of standard IEEE 802.11e with the standard IEEE 802.11 without quality of set-vice, a simulation of these standards is performed by using the network simulator simulator. We test also the mobility and the roaming of stations. A discussion is presented in detail using simulation-based evaluations and we let its confirm the quality of service of IEEE 802.11 e compared to IEEE 802.11, but we have detected some weaknesses of 802.11e. It starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate Of weight of queues, so there is an unbalance enters the flows with high priorities.","Title: Design of New Aggregation Techniques for Wireless Sensor Networks\nYear: 2010\n\nAbstract: This paper compares different alternative aggregation techniques for Wireless Sensor Networks Optimization based on tree construction. The main idea is to efficiently elect parent nodes responsible of data aggregation according to their connectivity degree. Thus, the quantity of data transmitted on the network remains minimal during the transfer from all sensors towards the sink. Simulations have shown that our new approach provides a better performance than existing techniques such as BFS, DFS and flooding, especially in terms of quantity of data packets transmitted from all sensor towards the sink.","Title: Analytical study of intradomain handover in multiple-mobile-routers-based multihomed NEMO networks\nYear: 2010\n\nAbstract: The need to stay connected to the Internet ''anytime'' and ''anywhere'' is becoming more and more required in the recent years with the development of wireless networks. The NEMO basic support protocol was developed to grant the Internet connection for an entire mobile network, like vehicle or aircraft network. In NEMO a Mobile Router manages the mobility of the entire network on behalf of the other nodes in order to reduce the overhead of signaling messages. The critical part of mobility support is to reduce the handover latency, particularly when a Mobile Router is not reachable. This handover period degrades the performance of most delay sensitive applications. Referring to our proposition for NEMO handover improvement which is conceived for multiple-mobile-routers-based multihomed NEMO network, we find out a mathematical model to study the intradomain handover performance. We derive the mathematical model to analyze interruption interval (the time interval during which none of mobile routers can transport packets) during the intradomain handover. We study the impact of varying critical parameters, like vehicle speed, overlapping coverage distance, distance between mobile routers, and scanning frequency. The obtained results reveal that the seamless handover can be achieved if network configuration parameters are correctly chosen.","Title: Power-law chord architecture in P2P overlays\nYear: 2008\n\nAbstract: In this paper, we propose to extend the topology of Chord to a bidirectional graph to provide a super-peer based lookup algorithm and an efficient resource localization service at a very little additional cost.","Title: On Analyzing the Potential of a Layer-2 Multi-hop Authentication and Credential Delivery Scheme for Vehicular Communications\nYear: 2009\n\nAbstract: In this paper we introduce a new security architecture and security mechanisms for vehicular networks providing a layer-2\n multi-hop authentication and credential delivery scheme between vehicles and the network operator authentication server. We\n present a performance analysis of the proposed solution under various vehicles and Access Points (APs) densities, showing\n the potential of our scheme in providing a more efficient, robust and scalable authentication and credential delivery to vehicles\n when compared against the classical single-hop scheme.","Title: Advance reservation optimization in IP-based mobile networks\nYear: 2009\n\nAbstract: To provide continuous Quality-of-Service in mobility scenarios, advance reservation should be performed at the location to which a mobile node is expected to move. However, since these reserved resources in advance are not used before the arrival of the mobile node (or only can be used by best effort flows), resource waste is involved. The issue how to minimize this waste is addressed in this paper. We propose, firstly, that advance reservation is triggered when the mobile node's distance to the edge of its serving access router's coverage area is optimal. A mathematical model is developed to calculate this optimal distance. In our analysis, we investigate the impact of some parameters on the optimal distance. Second, we demonstrate that path-decoupled reservation technique can provide better performance than path-coupled reservation when being adopted for mobility scenarios, because path-decoupled reservation incurs much less setup delay. The impact of the reservation delay on session's success probability and access router's capacity is analyzed","Title: Event Based Mobility Model for Subway Scenarios\nYear: 2007\n\nAbstract: High cost and complexity of Mobile Ad hoc NETworks (MANETs) testbeds let simulation as the best solution to experiment MANETs protocols and applications. Thus improving current simulation tools become crucial to provide valuable results. Mobility and propagation models are key element to realistically simulate user's behaviour and wave propagations and therefore assure the validity of the simulations results. Unfortunately, accurate mobility models are complex and consider a wide range of parameters. Indeed to reflect reality every detail which may modify the mobility of users has to be included in the models. Consequently most of the realistic simulations models are not scalable and involve excessive computation time. Furthermore, these models are very generic and fail to capture the impact of event in real environments. In this paper we present an accurate Subway Mobility Model which requires only few parameters. Moreover the simulated environment represents an application prolific context which can easily be set up. Finally we provide average simulation execution time for large networks and a comparison with the Random Waypoint model","Title: RVP: A New Policy for Aggregate Reservation\nYear: 2008\n\nAbstract: Reservation aggregation provides scalability to the IETF Integrated Services (IntServ) by reducing the high number of states stored at internal routers and the number of signalling messages processed at these routers. However, the latter benefit will be lost if the bandwidth of aggregate reservation changes frequently. Hence, previous works either hold resource requests during a waiting period before sending a single aggregate reservation for all received requests, or reserve maximum resources which will be requested in the following period. However these works involve an assumption of arrival distribution of resource requests. In this paper, we design a policy for enhancing the reservation aggregation performance, which is independent of arrival distribution. From the results of simulation, we observe that this policy outperforms other policies.","Title: Opportunistic Trajectory-Based Routing For V2v Communications\nYear: 2011\n\nAbstract: In this paper, we propose enhanced Simple Forwarding over Trajectory (eSIFT), a novel opportunistic trajectory-based routing protocol for Vehicular Ad hoc Networks (VANETs), based on Simple Forwarding over Trajectory (SIFT). eSIFT is designed to operate in highly dynamic vehicular networks for data dissemination. eSIFT presents advantages such as no discovery step and low overhead. We also present performance evaluation results of eSIFT, in comparison to SIFT. Simulations show that eSIFT improves SIFT, in particular in term of delay, and slightly in term of hop count and packet delivery ratio.","Title: Performance Evaluation of Hybrid Channel Assignment for Wireless Sensor Networks\nYear: 2012\n\nAbstract: Data transmission in Wireless Sensor Networks (WSNs) is physically constrained by interference, throughput, latency and many other physical phenomena. We propose a distributed hybrid algorithm to perform the selection of communication channels in such a way that overall throughput, latency, energy and overhead are improved. A tree structure is built out from the sink, in order to elect sensors with the highest degree of connectivity as parents, and sensors with the lowest degree of connectivity as leaves. A set of parents and leaves are assigned to a single fixed channel. Specific sensors, called mediators, are assigned to several orthogonal channels. So, they can switch dynamically to the static channels of parents for collecting the data. This allows the data to be efficiently propagated in parallel on multiple channels from parent to mediator to parent towards the sink. We compare the results obtained with those for single and multiple channels by taking sink throughput, broadcast latency, energy consumption and routing overhead as performance criteria. We show that our method provides better results.","Title: CATS: An adaptive traffic signal system based on car-to-car communication.\nYear: 2013\n\nAbstract: Traffic signal controls play an important role in regulating vehicular flow at road intersections. Traditional systems are not capable of adjusting the timing pattern in accordance with vehicular demand. This results in excessive delays for road users. Hence it is necessary to develop dynamic systems that can adjust the timing patterns according to traffic demand. In this paper, the design and implementation of an adaptive traffic signal control system based on car-to-car communication is presented. Also, a clustering algorithm is defined which will assist in estimating the density of vehicles approaching an intersection. The cycle time, which is calculated using the estimated density of vehicular traffic, helps in reducing both the waiting time for vehicles at intersections and queue length. It is also shown that the proposed solution is collision free at intersections. The proposed system is compared with a classic pre-timed system and an adaptive fuzzy logic system. The simulations also show that the data convergence time and the communication delay between vehicles and traffic signals do not compromise the efficiency of the system.","Title: Aggregation methods for integrated services\nYear: 2011\n\nAbstract: Reservation aggregation provides scalability to the IETF Integrated Services (IntServ) by reducing the high number of states stored at internal routers and the number of signaling messages processed at these routers. However, in the case of frequent joining and leaving of individual flows, the latter benefit will be lost due to frequent adjustment of aggregation size. In this paper, to reduce aggregation adjustment frequency, we focus on investigating two critical parameters: aggregation size and the lower threshold. We propose two policies to find out the optimal values of these criteria. One policy called Two Bounded operating Policy (TBP) is parameter-based policy and the other called Resource request Variance Policy (RVP) is measure-based policy. The calculation of these optimal values considers three costs: underutilization cost, signaling cost and holding cost. In our evaluation study, we compare the proposed two policies with two others, Temporal Operating Policy (TOP) and Cardinal Operating Policy (COP). This study shows that our mechanisms outperform the previous propositions in terms of cost and blocking ratio. Copyright © 2011 John Wiley & Sons, Ltd.","Title: Performance analysis of position-based routing approaches in VANETS.\nYear: 2007\n\nAbstract: This article presents a performance analysis between two location-based routing protocols: SIFT (SImple Forwarding over Trajectory), a novel, scalable, spatial-aware, trajectory-based approach, and DREAM (Distance Routing Effect Algorithm for Mobility), a stable, largely tested position-based scheme. The study was accomplished under a realistic urban mobility model for VANETS (Vehicular Ad hoc NETworks), within a highly deployed evaluation network of up to 1000 nodes. Classical ad hoc routing schemes do not perform well in VANETS because they were not designed to handle efficiently mobility handicaps. Position-based techniques perform better in dynamic scenarios, but in some highly dynamic scenarios, like VANETS, they do not always perform efficiently. Trajectory-based protocols perform more efficiently in VANETS since they are spatial-aware. We demonstrate that SIFT performs better than DREAM in a realistic VANET scenario concerning delivery ratio, control overhead, delivery delay, and route length.","Title: Cooperation Optimized Design for Information Dissemination in Vehicular Networks using Evolutionary Game Theory\nYear: 2013\n\nAbstract: We present an evolutionary game theoretic approach to study node cooperation behavior in wireless ad hoc networks. Evolutionary game theory (EGT) has been used to study the conditions governing the growth of cooperation behavior in biological and social networks. We propose a model of node cooperation behavior in dynamic wireless networks such as vehicular networks. Our work is motivated by the fact that, similar to existing EGT studies, node behavior in dynamic wireless networks is characterized by decision making that only depends on the immediate neighborhood. We adapt our model to study cooperation behavior in the context of information dissemination in wireless networks. We obtain conditions that determine whether a network evolves to a state of complete cooperation from all nodes. Finally, we use our model to study the evolution of cooperation behavior and its impact on content downloading in vehicular networks, taking into consideration realistic network conditions.","Title: ScatterPastry: An Overlay Routing Using a DHT over Wireless Sensor Networks\nYear: 2007\n\nAbstract: Using Distributed Hash Tables (DHTs) over ad-hoc wireless sensor networks (WSNs) has gained a lot of attention in the research arena in last years. In WSN's world, the most important issue in routing is to gather the routed information coming from sensor nodes to the sink node regardless of the identity of the donating node. The problem in this context is to locate efficiently the sensor node, which holds the data item with the minimum number of intermediate nodes to save network energy. DHTs based on the Internet are used for this purpose. This paper presents a ScatterPastry platform based on Pastry DHT as an overlay routing platform for distributed applications over WSNs using Scatterweb nodes, a real-world wireless sensor platform.","Title: VANET Inherent Capacity for Offloading Wireless Cellular Infrastructure: An Analytical Study.\nYear: 2014\n\nAbstract: Due to the high user traffic demand increase, offloading cellular traffic through other kinds of networks, such as Wi-Fi hotspots and femtoCells has been highly studied. In this paper, we investigate upon the possibility to use Vehicular ad hoc Networks (VANETs) for the offloading the cellular infrastructure. We present an analytical study based on an optimization problem formulation where the aim is to select a maximum target set of flows that could be routed to the destination downloader node through the VANET network. The offloading decision considers the vehicular link availability, channel load by considering medium contention, vehicle to vehicle link quality and the link connectivity duration between the VANET node and the road side unit. Simulation results of our analytical approach show that the data offloading fraction is closely affected by the data volume of the flows, the channel load and by the link quality. Results show also that the offload of best effort data traffics could reach 100 percent for low data volumes.","Title: A global security architecture for operated hybrid WLAN mesh networks\nYear: 2010\n\nAbstract: Hybrid Wireless Mesh Network (HWMN) is a new wireless networking paradigm. Unlike traditional wireless networks, in HWMNs, hosts may rely on each other to keep the network connected. Operators and wireless internet service providers are choosing HWMNs to offer Internet connectivity, as it allows fast, easy and affordable network deployments. One main challenge in design of these networks is their vulnerability to security attacks. In this paper, we investigate the main security issues focusing on the most vulnerable part of the hybrid WLAN mesh infrastructure which concerns the ad hoc network part. Through our proposed architecture, Security Architecture for Operator's Hybrid WLAN Mesh Network (SATHAME), we identify the new challenges and opportunities posed by this emerging networking environment and explore approaches to secure users, data and communications. From the analysis of strengths and weaknesses of secured routing protocols, we designed a new robust routing structure called MacroGraph (MG). MG structure is extracted from the mesh ad hoc network for each communication to be established between a source and a destination. Especially, MG is a robust structure based on node-disjoint path routing scheme and dynamic trust management that can be adapted to respond to applications' security requirements. We present a performance analysis of our efficient, robust and scalable multipath reactive secured routing protocol. We investigate the behavior of our proposed scheme under two attack scenarios: Packet Dropping and Route Error attacks in dense network configurations.","Title: An Efficient Scalable Trajectory Based Forwarding Scheme for VANETs\nYear: 2010\n\nAbstract: The past few years have seen an increasing interest in the development of vehicular ad hoc networks resulting in many routing protocols proposals. Scalability issues in such networks are attracting increasing attention these days. To improve data delivery performance in large scale networks, we propose SIFT, a trajectory based routing scheme that requires sparse infrastructure and rely on low quality information. It merely uses the trajectory and the location of the last node that forwarded the packet to forward a data packet from a source to a destination. SIFT is evaluated against DREAM, a well-known routing protocol from the literature through realistic simulations using Omnet++. Simulation results demonstrate that under dense deployment, using a realistic mobility model scenario, the proposed scheme performs better in terms of delivery ratio, end-to-end delay and route length.","Title: Symmetric replication for efficient flooding in DHTs\nYear: 2008\n\nAbstract: To support complex queries and broadcast in DHTs, we propose an algorithm for an effective flooding that we implement and compare in a Chord DHT. We use flooding and replication that exploit structural constraints to achieve lower overhead and higher reliability.","Title: ASMA : Towards Adaptive Secured Multipath in MANETs\nYear: 2006\n\nAbstract: As they are used to create open communities, Mobile Ad hoc NETworks (MANETs) are not favourable environments to establish trust, which is necessary to provide security. Multipath routing mechanisms within infrastructureless networks environment seems appropriate and useful to enhance security protection. In fact, the level of trust can be increased so as many of potential security attacks are detected, revealed and stopped. Nevertheless an excessive control overhead is always generated. In this paper, we propose a global framework that integrates a set of concepts and mechanisms aiming at enhancing security in highly dynamic decentralized ad hoc networks. Our solution focuses on authentication, routing securing, trust management with reliable estimation of trust. A large panoply of attacks are prevented using our various mechanisms.","Title: MA-WATM: a new approach towards an adaptive wireless ATM network\nYear: 1999\n\nAbstract: In a cellular multimedia network like wireless ATM (WATM), self control seems primordial. Our new approach is based on the application of DAI (distributed artificial intelligence) techniques in order to build a self-adaptive network within random non-uniform traffic conditions. Attempting to achieve a high network capacity in terms of resource allocation and air interface BER (bit error rate), we propose to apply intelligent agent features to enhance the architecture of WATM systems. In fact, the intelligent platform MA-WATM (multi-agent wireless ATM) is used to provide a flexible integration of the multi-agent technique in wireless entities, BSs (base stations), MSs (mobile stations) and MSCs (mobile switching centers). Two applications are investigated and explored by simulations in order to bear out the feasibility of the multi-agent approach.","Title: A construction scheme for scale free DHT-based networks\nYear: 2009\n\nAbstract: In this paper, we propose PowerDHT, a novel scheme to extend the classic DHT-based overlay to a network with scale free-like properties. PowerDHT has a distributed rewiring method to improve the structure of the overlay network to a power-law-like graph. Our scheme is characterized through minimal, typically local-only, changes. Through simulations, we show that our proposal constructs an overlay network with an extended peer's neighborhood knowledge and a reduced network diameter at no additional cost and that it supports a more effective flooding e.g. for generic search.","Title: Effect of Sink Location on Aggregation Based on Degree of Connectivity for Wireless Sensor Networks\nYear: 2011\n\nAbstract: In this paper we study the effect of sink location on aggregation through many random Wireless Sensor Network topologies based on tree construction. The key idea is to build the tree out from the sink, taking into account node's degree of connectivity, in order to elect the node with the highest degree of connectivity as a parent, and the node with lowest degree of connectivity as a leaf. The shortest path between each sensor and the sink is established. Thus, the data transmitted on the network remains minimal and will propagate from parent to parent towards the sink. We then select the best location of the sink in order to obtain the minimal number of packets transmitted from all sensors towards the sink, and the maximum number of leaves. Simulations have shown that our new method provides promising results that are better than existing algorithms such as BFS, DFS and flooding.","Title: An efficient qos based gateway selection algorithm for VANET to LTE advanced hybrid cellular network\nYear: 2012\n\nAbstract: In this paper, we address the gateway selection issue in a hybrid system composed of a VANET network and a 4G LTE Advanced infrastructure. The VANET network is structured via a clustering scheme. Our algorithm is based on a multi-criteria and QoS related attributes approach used to make a decision of the appropriate gateway that might be used to connect a source vehicle to the LTE Advanced infrastructure. Considered criteria for making the decision include load, Received Signal Strength and Link Connectivity Duration of the cluster head and other candidate gateways. Simulation results demonstrate that our algorithm makes efficient decisions for electing the appropriate gateway with the best VANET and infrastructure features.","Title: Performance evaluation of replication strategies in DHTs under churn\nYear: 2007\n\nAbstract: This paper presents a comparative analysis of replication algorithms for DHT (Distributed Hash Table) architectures. These algorithms are applicable to all existing structured peer-to-peer systems, and can be implemented on top of any DHT. The performance of these algorithms is examined using emulation through virtualization. Significant differences are identified in terms of delays, control overhead, success rate, and overlay route length.","Title: Energy Consumption Routing for Mobile Ad Hoc Networks\nYear: 2003\n\nAbstract: The specific features of mobile ad hoc networks (MANETs) impose new requirements for routing protocols. The aim of this paper is to present an approach that enhances routing performance by integrating ad hoc related characteristics. We propose a loop-free adaptive path energy conserving scheme which attempts to minimize both routing and storage overhead in order to provide efficiently robustness to host mobility, adaptability to wireless channel fluctuations and optimization of network resources use in large-scale networks. The strength of our scheme, based on source routing approach, named Energy Conserving Routing (ECR), is to handle network state related constraints such as node's energy consumption, link availability and path quality. The performance of the proposed scheme is evaluated via simulation and is compared to DSR protocol. Better results are obtained with ECR in terms of path lifetime, forwarding efficiency, delay, and total overhead.","Title: Symmetric routing in DHT overlays\nYear: 2011\n\nAbstract: In this paper, we propose to extend the DHT topology to a bidirectional graph to provide a super-peer based lookup algorithm and a scalable search support. We consider routing algorithms for a bidirectional variant of the DHT network and show how the resulting structure extends the search region and provides an efficient resource lookup service at a very little additional cost.","Title: Mini-sink mobility with diversity-based routing in wireless sensor networks\nYear: 2011\n\nAbstract: The performance of Wireless Sensor Networks (WSNs) is constrained by congestion, latency, data loss and other phenomena. In this paper, we propose a model based on the use of Mini-Sinks (MSs), each with considerable storage capacity, instead of a single sink for collecting the data. The idea is that one or more MS are mobile and move according to an arbitrary mobility model inside the sensor field to collect data within their coverage areas and forward it towards the sink. Energy Conserving Routing Protocol (ECRP), based on route diversity, is implemented in MSs and sensors in order to optimize the transmission cost of the forwarding scheme. A set of multiple paths between MSs and sensors is generated to reduce local congestion phenomena and to distribute the global traffic over the entire network. Since a topology incorporating MSs changes constantly due to their mobility, we analyze the impact of global connectivity for a given WSN. Simulations were performed in order to validate the performance of our model. We compare the results obtained with those for a single static sink, and show that our model gives better results in terms of lower congestion, energy consumption and broadcast latency.","Title: LTE Advanced Relaying Standard: A Survey\nYear: 2013\n\nAbstract: Long term evolution (LTE) Advanced is a well designed system that meets the requirements of 4G cellular systems. Its standard specification has been lately released. One of its main features is supporting relaying topology inspired from ad hoc multihop networks. This paper is a survey upon the relaying architecture of LTE Advanced standard based on 3GPP Release 10 specifications. A comparison with other relaying architectures, i.e. IEEE 802.16m and IEEE 802.11s is handled. The originality of this work is in involving comparison with multihop architecture supported by IEEE 802.11s based wireless mesh networks. Several similarities are noted and differences are pointed out.","Title: A Fuzzy Multi-Metric QoS-Balancing Gateway Selection Algorithm in a Clustered VANET to LTE Advanced Hybrid Cellular Network\nYear: 2015\n\nAbstract: Intelligent transportation systems are currently attracting the attention of the research community and the automotive industry, which both aim to provide not only more safety in the transportation systems but other high-quality services and applications for their customers as well. In this paper, we propose a cooperative traffic transmission algorithm in a joint vehicular ad hoc network-Long Term Evolution Advanced (LTE Advanced) hybrid network architecture that elects a gateway to connect the source vehicle to the LTE Advanced infrastructure under the scope of vehicle-to-infrastructure (V2I) communications. The originality of the proposed fuzzy quality-of-service (QoS)-balancing gateway selection (FQGwS) algorithm is the consideration of QoS traffic class constraints for electing the gateway. Our algorithm is a multicriteria and QoS-based scheme optimized by performing the fuzzy logic to make the decision on the appropriate gateway. Criteria are related to the received signal strength (RSS) and load of the cluster head (CH) and gateway candidates (GwCs), as well as the vehicle-to-vehicle link connectivity duration (LCD). Simulation results demonstrate that our algorithm gets better results than the deterministic scheme for gateway selection. Moreover, results show the efficiency of the FQGwS algorithm as it adapts its gateway selection decision to the cluster density and the relative velocity of the source node.","Title: Performance analysis of a cross-layered incremental redundancy hybrid automatic repeat request (CL IR-HARQ) mechanism\nYear: 2014\n\nAbstract: The performance of Hybrid Automatic Repeat reQuest (HARQ) in wireless networks has been extensively studied in recent years. Most of the HARQ performance results reported in the literature have been based on cross-layer techniques making use of Media Access Control (MAC) and physical layer information. In contrast, we present a performance analysis of a cross-layer approach that uses MAC and Internet Protocol (IP) layer information to efficiently control packet retransmissions in wireless networks. Evaluation results (using performance metrics such as packet error rate, retransmission efficiency, delay) obtained at the IP layer, using a two-state Gilbert Elliott channel model, demonstrate the significant performance improvements of the (MAC-IP) cross-layer strategy.","Title: FQGwS: A gateway selection algorithm in a hybrid clustered VANET LTE-advanced network: Complexity and performances.\nYear: 2014\n\nAbstract: In this paper, we propose a cooperative traffic transmission algorithm in a joint cellular and vehicular ad hoc hybrid network architecture. We focus on defining an algorithm aiming to select the appropriate gateway for a given source vehicle under the scope of vehicle to infrastructure communications. We consider the LTE Advanced infrastructure and propose a multi-criteria and attribute scheme named FQGwS algorithm. It is a QoS-balancing gateway selection algorithm where the decision over the gateway depends on the class of traffics to be transmitted to the infrastructure. A study of the complexity and the convergence of the algorithm is handled. Moreover, simulation results show that the packet loss is always lower than 1% and that the average delay never exceeds the delay constraint of the QoS class unlike when using the deterministic scheme.","Title: Hybrid Handover Optimization For Multiple Mobile Routers-Based Multihomed Nemo Networks\nYear: 2007\n\nAbstract: Network mobility (NEMO) provides continuous connectivity to the Internet to a mobile network when moving from one access router to another. Because of link switching delay and IP protocol operation, packets destined to a mobile network can be delayed or lost during handover period. This paper proposes a solution to improve NEMO handover performance for one kind of multihomed NEMO configuration (multiple mobile routers are located in a mobile network). To manage the traffic between access routers and mobile routers, a new control entity is introduced in order to provide low latency and no packet loss. This entity is also responsible to select the next access point for mobile router when the latter detects its movement. Using this hybrid approach, mobile router can predict a handover and has the best knowledge regarding its current location and state to initiate the handover. In addition, thanks to this entity, mobile router can, based on its current state, perform handover with different strategies, so as to improve handover performance. Despite this new mechanism, no additional function is required to mobile router in our proposition.We have carried out a comparison study of handover performance with NEMO basic protocol, and showed that our proposed scheme provides near-optimal performance in both intradomain and interdomain handover. Furthermore, certain parameters, the distance between two related MRs, the distance of overlapping area and the mobile network speed, which affect the performance of our proposition have also been studied. The results show that seamless handover can be achieved if these parameters are rightly configured.","Title: A traffic QoS aware approach for cellular infrastructure offloading using VANETs.\nYear: 2014\n\nAbstract: Offloading a part of cellular traffic through other kinds of networks, such as Wi-Fi hotspots and femtoCells represents an interesting solution for operators to cope with the high user traffic demand increase. In this paper, we propose to use the Vehicular ad hoc Networks (VANETs) for the same purpose. We present an analytical study based on an optimization problem formulation to evaluate the potential of VANET to vehicle part of the cellular traffic. The offloading decision considers several constraints related to vehicle-to-infrastructure link availability, channel and medium contention, vehicle-to-vehicle link capacity and quality, data flows volume and the link connectivity duration between the vehicle and the road side unit. Moreover, the originality of this work is the consideration of flow's service class in the offloading decision. Numerical results show that the data offloading fraction is closely affected by the data volume of the flows and by vehicular link quality. Results show also that best effort and background traffics have more priority to be offloaded than the video streaming traffics.","Title: Information dissemination in vehicular networks via evolutionary game theory\nYear: 2014\n\nAbstract: We study the problem of information dissemination in vehicular networks in this paper. Crucial information, such as traffic jamming status, is usually broadcasted inside the network. Each vehicle in the network has its own choice to either forward or drop packets for others. Although the energy consumption in general is not an issue in vehicular networks, forwarding every received packets is still not preferred as it may result in congestion in transmission. We model this problem via evolutionary game theory to investigate the cooperative behavior among vehicles. Simulation results show that, the cooperation ratio in the network is proportional to the setting of synergy factor for the evolutionary game. When nodes change their strategies according to the evolutionary game, information can be disseminated as fast as flooding scheme, while more bandwidth can be reserved.","Title: Towards a Cooperative ITS Vehicle Application Oriented Security Framework\nYear: 2014\n\nAbstract: Automotive industry is interested to ITS as it provides attractive services for connected vehicles aiming at creating a new and very promising business market. However, the security remains a major challenge for the ITS deployment as several critical threats has been identified. In this paper, we present our Cooperative ITS Vehicle Application Oriented Security Framework CIVAS for vehicle ITS stations. Our focus is given first to ITS vehicle security requirements and constraints. Then, we provide an overview of the “Defense-in-Depth” model that we adapted for securing ITS vehicle. The proposed security framework follows a modular design and is application oriented. To illustrate the interaction between designed CIVAS layers, we consider a vehicle stationary as example of a road safety use case.","Title: A performance analysis of source routing-based multicast protocol (SRMP) using different mobility models\nYear: 2004\n\nAbstract: We focus on one critical issue in mobile ad hoc networks (MANETs) that is multicast routing. In fact, optimal routes, stable links, power conservation, loop freedom, and reduced channel overhead are the main features to be addressed in a more efficient multicast mechanism. MANETs are often analyzed through simulations and their performance results depend slightly on simulation network parameters including traffic generation models, radio transmission parameters and mobility models. In this paper we evaluate the performance of our proposed multicast routing protocol, named source routing-based multicast protocol (SRMP). SRMP constructs a mesh to connect group members, providing robustness against mobility. It also provides stable paths based on links availability according to future prediction of links state, and higher battery life paths tending to power conserving. We present a full performance evaluation and analysis for SRMP under realistic conditions including, realistic movements of mobile nodes in the form of different mobility models. We present our simulation results that illustrate the importance of choosing a mobility model in the simulation. Specifically, we illustrate the effect of choosing the mobility model on the performance results.","Title: An efficient micromobility implementation for 802.1X WLANs\nYear: 2004\n\nAbstract: We analyze the implications of the integration of the current IP micromobility concepts with the 802.1X access control. We show that the independent user location tracking of IP micromobility and 802.1X provokes a significant additional handover delay and signaling load degrading the overall performance. To overcome these difficulties, we propose a system architecture which uses EAP as a general signaling protocol. We then discuss the new opportunities of our approach. Finally, we show that our system architecture can be applied in almost all access networks by exploiting the generality of the 802.1X approach.","Title: KMS: a key management system for multi-provider interconnected Wi-Fi WLANs\nYear: 2004\n\nAbstract: The fundamental goal in future mobile multiservice networks is to provide an efficient mobile computing environment which enables a user with a portable computer equipped with multiple wireless access interfaces to move seamlessly between different providers' networks. In particular, if these networks are Wi-Fi WLANs (wireless fidelity wireless local area networks), security features should be defined precisely taking into account seamless roaming. The paper considers one of the most critical security issues in Wi-Fi networks -key management. We propose a centralized approach to deal with key management in the case of an interconnection of remoted Wi-Fi networks based on using a key management server. Security goals and system architecture guidelines are outlined. In respect to the IEEE 802.11i standard, the changing of keys requires only 3 messages and the roaming situation allows the establishment of a new secure 802.11 wireless channel by exchanging only 5 messages against at least 20 messages.","Title: Hybrid Wireless Networks: Applications, Architectures and New Perspectives\nYear: 2006\n\nAbstract: With the advent and ubiquitous of wireless technology, a wide range of advanced services are expected to be supported including appealing services that currently exist in wired systems. Nevertheless, the resource constraints in wireless environment may render difficulty to realizing all the desirable services. Consequently, an infrastructure with high data rate is necessary to complement the resource constraints and to act as anchor points linking mobile nodes to other fixed networks as the Internet. Hybrid wireless networks have emerged as a promising solution, allowing mobile clients to achieve higher performance and service access in a seamless manner independent of their existence in wireless LAN (WLAN) communication range. In this paper we address the benefits of hybrid wireless networks, showing their possible applications and presenting a classification for their emerging architectures. Also, we identify the research challenge arising from the problem of applying the grid computing concept in such hybrid wireless environment, showing the expected benefits from the aggregated fixed-mobile capacity. Finally, we propose our vision for a potential architectural model, which is expected to provide useful services by the network operator or the service provider in such a hybrid environment","Title: A Bayesian Filter to Detect Misbehaving Nodes in MANETs\nYear: 2008\n\nAbstract: Composed of mobile nodes, MANETs rely on the entire collaboration of nodes to provide routing and forwarding functions. Most MANET security solutions identify and exclude malicious and selfish nodes. These mechanisms rely on local monitoring tools to detect untrustworthy nodes and then spread trust information through recommendations. In this paper we apply a Bayesian model [1] to improve MANET security. We classify nodes behavior relying on a decision based on a probabilistic Bayesian model. The novelty of our approach is that it classifies nodes based on distant observations. We describe statistical parameters like Accuracy, Error and the Total Cost Ratio that are used to evaluate the efficiency of the filter through a set of simulations of an attacked pure ad hoc network.","Title: A cross layer attack against MANET cooperation enforcement tools\nYear: 2008\n\nAbstract: Composed of mobile nodes, MANETs rely on the entire collaboration of nodes to provide routing and forwarding functions. Many solutions have been proposed to enforce the collaboration of nodes in MANETs. Most of them rely on monitoring mechanisms to detect selfish or malicious behaviors. These mechanisms have in common the implicit use of MAC layer information in their detection process. This paper presents a new attack scheme against MANET monitoring tools. Our attack scheme takes advantage of MAC layer absence of authentication to spoof the identity of honest nodes and ruin their reputations. Simulations have been carried out to evaluate the potential of the attack on current cooperation mechanisms. Results emphasize the high vulnerability of current monitoring mechanisms and underline the necessity for cooperation enforcement tools to rely only on authenticated information.","Title: ECTC: Energy effiCient topology control algorithm for wireless sensor networks\nYear: 2009\n\nAbstract: Sensor network which operates on battery are used to gather data in a variety of environments. The data collected by each node is communicated through the network to the sink, which uses all reported data to determine characteristics of the environment or detect an event. Prolonging sensor's operable lifetime is a main design challenge of these networks. A good energy saving technique in this direction is to schedule nodes sleep interval with the communication radio turned off. In this paper, we propose a distributed topology control algorithm, termed ECTC, which uses a clustering approach. It is built on the notion that when a region of a shared channel wireless sensor network has a sufficient density of nodes, significant energy saving is obtained by allowing redundant nodes to sleep. Using the two-hop neighborhood information, certain nodes sequentially select a subset of nodes to be active among all nodes in the neighborhood, to ensure connectivity. Moreover, to ensure fairness, the role of active nodes is rotated periodically to ensure energy-balanced operations. Results from stochastic geometry are used to derive solutions for the values of parameters of our algorithm that minimize the total energy spent in the network when all sensor nodes report data through the cluster heads to the sink.","Title: Controlled data collection of Mini-Sinks for maximizing packet delivery ratio and throughput using multiple paths in Wireless Sensor Networks\nYear: 2012\n\nAbstract: We propose a new approach based on the use of many data collectors, which we designate Mini-Sinks (MSs), instead of a single sink in order to improve Wireless Sensor Network (WSN) performances. One or more MSs are mobile and move according to an arbitrary mobility model inside the sensor field in order to maintain a fully-connected network topology, collecting data based on the controlled Energy Conserving Routing Protocol (ECRP) within their coverage areas and forwarding it towards the single main sink. ECRP, based on route diversity, is implemented in MSs and sensors in order to optimize the transmission cost of the forwarding scheme. A set of multiple paths between MSs and sensors is generated to distribute the global traffic over the entire network. Simulations were performed in order to validate the performance of our new approach. We compare the results obtained with those for a single static sink and mobile sink, and show that our approach can achieve better results in terms of packet delivery ratio, throughput, end-to-end delay and multiple paths overhead.","Title: A performance analysis of VANETs routing protocols using different mobility models\nYear: 2010\n\nAbstract: In order to evaluate a vehicular network performance it is important to develop and use mobility models that accurately capture the realistic mobility characteristics of moving vehicles. In this paper, we present performance evaluation of various routing protocols including SIFT, GPSR and GOSR using different mobility models such as Random Waypoint Model (RWM), Fluid Traffic Model (FTM) and Intelligent Driver Model with Intersection Management (IDM-IM). We present simulation results that illustrate the importance of choosing a mobility model in the simulation of a vehicular network protocol. We illustrate how the performance results considerably change as a result of changing the simulated mobility model. We show how unreliable results can be obtained by using some models such as RWM and FTM. In addition, we demonstrate how more realistic mobility models such as IDM-IM often lead to more accurate results.","Title: Safety message dissemination in VANETs: Flooding or trajectory-based?\nYear: 2010\n\nAbstract: In this paper, we address the reliable alarm message dissemination in Vehicular Ad hoc NETworks (VANETs) environment. We study various techniques to disseminate emergency data, after a car crash, within a group of vehicles. We consider a trajectory-based data dissemination technique to perform broadcast flooding task optimization, and compare it with a pure flooding scheme. For the evaluation, we examine various parameters such as inter-vehicle distance, transmission radio range and traffic load. Experimental results, obtained by several simulations implemented on VanetMobiSim/NS-2 platform, show the effectiveness of trajectory-based solutions for efficient dissemination of emergency messages in VANETs. We also conclude that a simple flooding technique is not always considered harmful, and can outperform more complicated schemes in high density VANETs environment.","Title: VANET Based Adaptive Traffic Signal Control\nYear: 2011\n\nAbstract: In urban scenarios traffic signal controls are the main mechanism to control vehicular flow at the intersections. However, traditional systems fail to adjust the timing pattern in accordance to the time variability. An alternative to such systems is to develop dynamic systems which will alter the timing patterns according to the traffic demand. In this paper, an adaptive traffic signal control system based on car-to-car communication is designed and developed. This system reduces the waiting time of the vehicles at the intersection along with the reduction in queue length. It's also verified that the proposed solution is collision free at the intersections. The proposed system is compared with a classical pre-timed system. The simulations also show that the data convergence time and the communication delay between vehicle and traffic signal do not compromise the efficiency of the system.","Title: A stable clustering algorithm for efficiency applications in VANETs\nYear: 2011\n\nAbstract: Efficiency applications in VANETs are focused on increasing the productivity of the road resources by managing the traffic flow and monitoring the road conditions. The performance of most such applications is dependent on an effective density estimation of the vehicles in the surroundings. Of the various methods, clustering demonstrates to be an effective concept to implement this. However due to high mobility a stable cluster, within a vehicular framework, is difficult to implement. In this work, we propose a direction based clustering algorithm with a clusterhead switching mechanism. This mechanism is aimed to overcome the influence of overtaking within the clusters. The proposed algorithm facilitates to attain better stability and thus accurate density estimation within the clusters. Simulation results show that the proposed clustering algorithm is rendered stability through switching mechanism and hence provides a better accuracy in density estimation.","Title: A multi-metric QoS-balancing scheme for gateway selection in a clustered hybrid VANET network\nYear: 2012\n\nAbstract: In this paper, we propose a cooperative traffic transmission algorithm in a joint cellular and mobile ad hoc hybrid network architecture. The mobile ad hoc network is based on IEEE 802.11p standard. The focus of this paper is on defining an algorithm aiming to select the appropriate gateway for a given source vehicle under the scope of V2I communications. In this work, we consider the LTE Advanced infrastructure. We propose a multi-criteria and attribute scheme used to make a decision over the appropriate gateway to connect a source vehicle to the LTE Advanced infrastructure. It is a QoS-balancing gateway selection algorithm where the decision over the gateway depends on the traffic to be transmitted to the infrastructure. Other criteria are also considered such as loads, Received Signal Strengths (RSS) and Link Connectivity Durations of the cluster head and other gateway candidates. Simulation results demonstrate that our algorithm makes efficient decisions for electing the appropriate gateway that fits best the cluster and infrastructure features. An improvement of the RSS and the Link Connectivity Durations, while comparing to the commonly used gateway selection scheme, is noted.","Title: Direction based clustering algorithm for data dissemination in vehicular networks\nYear: 2009\n\nAbstract: Vehicular ad hoc networks (VANETs) are important component for the development of Intelligent Transportation System. Due to the features of VANET, data dissemination is an important issue that has to be addressed. In this paper we propose a direction based clustering algorithm for data dissemination. This protocol is used to estimate the density of vehicles on a given road. As in any clustering algorithm, the formation of the cluster and the use of the bandwidth are important tasks. In the proposed solution the packet is forwarded to vehicles only if they are moving along the same direction. The simulations show that the proposed protocol reduces the number of broadcast packets being sent on the network. To choose the best technology for VANET applications, the technologies 802.11p and 802.11b are compared with TCP/IP and Wireless Access Vehicular Environment (WAVE) stack protocols. This results obtained shows that WAVE stack is better than TCP/IP stack, in terms of performance, in vehicular environment.","Title: Physical rate and contention window based admission control (PRCW) for 802.11 WLANs\nYear: 2010\n\nAbstract: Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents a class based admission control algorithm for 802.11e based wireless local area networks. The strengths of our admission control is dynamicity and flexibility of the algorithm, which adapts to the situation of the BSS, like global load, number of best effort AC, and position of QSTA by report of QAP, thing that have never been taken together, but each solutions have used a point of sight separately. Thus it achieves higher throughput than other admission control for 802.11 e. The idea which consists of changing parameters [AIFSN, CWmin and CWmax] of best effort flows, for decreasing collisions, is used, so we think that it is an efficient way to protect QoS flows from best effort flows, and to allow reducing then number of collisions. So we increase AIFSN [best effort flow], CWmin and CWmax only at 70% of load of network, to prevent starvations of best effort flows, and so we increase rate utilization of channel. We also use the current rate transmission of QSTAs, according to their positions, instead of the minimum rate transmission used by standard 802.11e, for calculate the load of network and derived the TXOPi necessary for all the stations, with i=1 to number of active stations. The 802.11e standard starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities. A discussion is presented in detail using simulation-based evaluations, with an aim of comparing results of our admission control algorithm, with the 802.11e standard and the F- - HCF algorithm. Results reveal an improvement of the network load and a decrease of the number of collisions.","Title: Cellular Content Download through a Vehicular Network: I2V Link Estimation\nYear: 2015\n\nAbstract: Cellular networks are facing serious traffic overload problems due to the high users traffic demands, emphasized by the important penetration of smart phones and their greedy applications. The originality of this paper is to investigate upon the use of Intelligent Transportation Systems (ITS) for offloading the cellular infrastructure. We provide an analytical study based on an optimization problem formulation where the aim is to select a maximum target set of flows to route through the Vehicular Ad hoc Network (VANET). Offloading decision considers the VANET link availability, channel load (using contention), vehicle to vehicle link quality and the maximum volume that could be offloaded from the road side unit to the vehicular nodes. Simulation results show that the data offloading fraction is closely tied to the data volume of the flows, to the channel load and to the path quality. Results show also that 100% of best effort data traffics could be offloaded in some specific scenarios.","Title: Security of C-ITS messages: A practical solution the ISE project demonstrator\nYear: 2015\n\nAbstract: Cooperative Intelligent Transport Systems (C-ITS) offer innovative ways of wireless communication between Intelligent Transport Systems (ITS) stations and ITS road-side stations. They favour the development of ITS applications to improve traffic management, road safety, mobility and other comfort services. C-ITS systems have to guarantee communication security, especially in heterogeneous network environments. Safety critical applications require authentication to avoid attackers to send spoofed or reforged information, nevertheless, cars and drivers privacy must be maintained. We present a demonstration of the C-ITS security management infrastructure of the ITS-Security (ISE) project [1]. Through our demonstrator we show how ISE provides message authentication without violating cars and drivers privacy. Our demonstrator allows the public to run an attack scenario with and without the ISE security system, making evident importance of securing ITS communications.","Title: RACE: Risk analysis for cooperative engines\nYear: 2015\n\nAbstract: Nowadays, Cooperative Intelligent Transport Systems (C-ITS) are not fiction anymore. Prototypes of self-driving vehicles are flourishing everywhere, e.g. Google driverless car. These new generation vehicles are not only intelligent as they do not need human intervention during cruise, but they also communicate together creating a cooperative network. However, C-ITS are becoming the prey of hackers and the target of cyberattacks. Consequently, a reliable risk analysis method needs to be defined to prevent C-ITS threats and to assess their vulnerabilities. In this paper, we define a simple and efficient risk analysis method called RACE. We compare it to two of main risk analysis methods, namely TVRA and EVITA.","Title: A new mobility-based clustering algorithm for vehicular ad hoc networks (VANETs).\nYear: 2016\n\nAbstract: Clustering in vehicular ad hoc networks (VANETs) is a challenging issue due to the highly dynamic vehicle mobility and frequent communication disconnections problems. Recent years' research have proven that mobility-based clustering mechanisms considering speed, moving direction, position, destination and density, were more effective in improving cluster stability. In this paper, we propose a new mobility-based and stability-based clustering algorithm (MSCA) for urban city scenario, which makes use of vehicle's moving direction, relative position and link lifetime estimation. We evaluate the performance of our proposed algorithm in terms of changing maximum lane speed and traffic flow rate. Our proposed algorithm performs well in terms of average cluster head lifetime and average number of clusters.","Title: A joint active time and flow selection model for cellular content retrieval through ITS.\nYear: 2016\n\nAbstract: Operators need to address increased data demands to meet subscribers' growing requirements by offloading a portion of cellular traffic onto other types of networks. In this paper, we investigate the possibility of using vehicular ad hoc networks (VANETs) for this purpose. We study joint data flow selection and contention resolution in a hybrid VANET-cellular system. We formulate the problem as an optimization problem called FOSAA, which considers vehicle-to-vehicle and vehicle-to-infrastructure link quality, channel access, inter-nodal interference and node active time. The problem is solved through an iterative approach. FOSAA is compared to other proposed schemes. The performance results show that offloading fraction is significantly affected by the data volume, vehicle density and number of hops from the infrastructure to the downloader vehicles.","Title: A Secure and Authenticated Key Management Protocol (SA-KMP) for Vehicular Networks.\nYear: 2017\n\nAbstract: Public key infrastructure (PKI) is the most widely used security mechanism for securing communications over the network. However, there are known performance issues, making it unsuitable for use in vehicular networks. In this paper, we propose a secure and authenticated key management protocol (SA-KMP) to overcome the shortcomings of the PKI. The SA-KMP scheme distributes repository containing the...","Title: A New Service Advertisement Message for ETSI ITS Environments: CAM-Infrastructure\nYear: 2016\n\nAbstract: Collaborative Intelligent Transportation Systems are almost part of our everyday life. A C-ITS environment can provide numerous services that soon will become essential to roads' users. The latter resides in improvement of road safety, entertainment, and commercial services. However to provide such services, the C-ITS environment needs an advertisement and dissemination service of the latter. Indeed, users have to be aware of the available services in order to request them if needed. Actual standards of service announcement show their limits, especially regarding the support of several communication profiles. For this reason, this paper, describes a new service advertisement message called CAM-Infrastructure. The latter is compliant with ETSI standards and is deployed in a nationwide scale project.","Title: Energy Efficient Multi-Layer Femtocell Networks\nYear: 2016\n\nAbstract: In this paper, we present an energy efficient routing algorithm for multi-layer femtocell networks. We consider a four-layered architecture that consists users, femtocells, relays, and macro base stations. The traffic to/from users passes through this architecture and is aggregated from/to the Internet through gateways in the relay layer. The traffic demand from users changes from time to time, so that some relays can be put into sleep mode in non-peak time to save energy. We propose a simple and effective routing algorithm to decide routes and active relays, to satisfy user traffic demand and save energy. Simulation results show that our proposed method outperforms benchmark schemes.","Title: Performance Evaluation of Link Metrics in Vehicle Networks: A Study from the Cologne Case.\nYear: 2016\n\nAbstract: In vehicle ad hoc networks, the link duration is an important concept for clustering and dissemination. Many link metrics are proposed to predict it based on the vehicles' velocities and distance between vehicles. However, there is a lack of comparison of these metrics under the same framework. In this paper, we compare several common adopted link metrics, LLT (link life time), SLS (spatial locality similarity), and SF (similarity function), in the performance of link duration prediction, according to a real vehicular mobility trace of the city of Cologne, Germany. We find that there exists a large gap in between the predicted link duration order and real link duration order for the real traffic trace, and there is no winning link metric in all scenarios. Furthermore, as an example, we show that, by combining existing link metrics intelligently, it is possible to create a new link metric that predicts link duration better.","Title: A non-biased trust model for wireless mesh networks.\nYear: 2017\n\nAbstract: Trust models that rely on recommendation trusts are vulnerable to badmouthing and ballot-stuffing attacks. To cope with these attacks, existing trust models use different trust aggregation techniques to process the recommendation trusts and combine them with the direct trust values to form a combined trust value. However, these trust models are biased as recommendation trusts that deviate too much from oneu0027s own opinion are discarded. In this paper, we propose a non-biased trust model that considers every recommendation trusts available regardless they are good or bad. Our trust model is based on a combination of 2 techniques: the dissimilarity test and the Dempster-Shafer Theory. The dissimilarity test determines the amount of conflict between 2 trust records, whereas the Dempster-Shafer Theory assigns belief functions based on the results of the dissimilarity test. Numerical results show that our trust model is robust against reputation-based attacks when compared to trust aggregation techniques such as the linear opinion pooling, subjective logic model, entropy-based probability model, and regression analysis. In addition, our model has been extensively tested using network simulator NS-3 in an Infrastructure-based wireless mesh networks and a Hybrid-based wireless mesh networks to demonstrate that it can mitigate blackhole and grayhole attacks.","Title: ASN.1 Specification for ETSI Certificates and Encoding Performance Study\nYear: 2017\n\nAbstract: Cooperative Intelligent Transportation Systems (C-ITS) are gaining ground and are almost part of our everyday life. Within these environments, huge amounts of messages are exchanged. Besides, these messages should be secure in order to ensure users' privacy. Public Key Infrastructures (PKI) represent the most common security solution. Due to the vehicles speed, the communication with the PKI should be fully optimized. The European Telecommunications Standards Institute (ETSI) proposes a PKI architecture for C-ITS environments. However, unlike most of security standards as IEEE 1609.2, there is no Abstract Syntax Notation One (ASN.1) specification for the used certificates. For this reason, in this paper, we propose an ASN.1 definition for the ETSI certificate to help developers in its implementation. In addition, we provide an extensive comparative study of the different encoding schemes, applied to this proposal.","Title: Tls For Cooperative Its Services\nYear: 2017\n\nAbstract: TLS is currently receiving much attention and seems to be the most promising candidate as a secure protocol for the current and future online services. Many security protocols have been developed to handle security problems in various circumstances. However, these protocols are often limited and related to precised contexts and architectures and cannot answer special application and networks needs such as securing transactions between several vehicles in vehicular networks. In this paper, we propose to extend the Transport Layer Security (TLS) protocol by using ETSI and IEEE certificates to securely exchange data between multiple vehicular network components through a single TLS session. We propose a formal validation of our extension with the HLPSL language using AVISPA. The proposed extension is currently being implemented over OPENSSL.","Title: A mobility-based scheme for dynamic clustering in vehicular ad-hoc networks (VANETs).\nYear: 2017\n\nAbstract: Vehicle clustering is an efficient approach to improve the scalability of networking protocols in vehicular ad-hoc networks (VANETs). However, some characteristics, like highly dynamic topology and intermittent connections, may affect the performance of the clustering. Establishing and maintaining stable clusters is becoming one of big challenging issues in VANETs. Recent years' researches prove that mobility metric based clustering schemes show better performance in improving cluster stability. Mobility metrics, including moving direction, vehicle density, relative velocity and relative distance, etc., are more suitable for VANETs instead of the received radio strength (RSS) and identifier number metrics, which are applied for MANETs clustering. In this paper, a new dynamic mobility-based and stability-based clustering scheme is introduced for urban city scenario. The proposed scheme applies vehicle's moving direction, relative position and link lifetime estimation. We compared the performance of our scheme with Lowest-ID and the most recent and the most cited clustering algorithm VMaSC in terms of cluster head duration, cluster member duration, number of clusters, cluster head change rate and number of state changes. The extensive simulation results showed that our proposed scheme shows a better stability performance.","Title: Link Duration Prediction in VANETs via AdaBoost.\nYear: 2017\n\nAbstract: In this paper, we present a link duration prediction method in VANETs. It utilizes AdaBoost algorithm to combine several link metrics, such as distance, difference in velocities, link lifetime, and etc., to form a predictor with a higher accuracy. The proposed method is applicable to different traffic scenarios and does not rely on any assumption of vehicles' velocity distribution. We evaluate the performance of this Adaboost-based link duration prediction algorithm by various traffic traces generated by SUMO that represents different typical scenarios. The evaluation result shows that, the proposed method effectively improve link prediction accuracy. Compared with other machine learning based solutions such as linear regression and support vector regression, the proposed method also shows less prediction error consistently.","Title: TEDS: A Trusted Entropy and Dempster Shafer Mechanism for Routing in Wireless Mesh Networks.\nYear: 2017\n\nAbstract: Wireless Mesh Networks (WMNs) have emerged as a key technology for the next generation of wireless networking due to its self-forming, self-organizing and self-healing properties. However, due to the multi-hop nature of communications in WMN, we cannot assume that all nodes in the network are cooperative. Nodes may drop all of the data packets they received to mount a Denial of Service (DoS) attack. In this paper, we proposed a lightweight trust detection mechanism called Trusted Entropy and Dempster Shafer (TEDS) to mitigate the effects of blackhole attacks. This novel idea combines entropy function and Dempster Shafer belief theory to derive a trust rating for a node. If the trust rating of a node is less than a threshold, it will be blacklisted and isolated from the network. In this way, the network can be assured of a secure end to end path free of malicious nodes for data forwarding. Our proposed idea has been extensively tested in simulation using network simulator NS-3 and simulation results show that we are able to improve the packet delivery ratio with slight increase in normalized routing overhead.","Title: SARA: Security Automotive Risk Analysis Method.\nYear: 2018\n\nAbstract: Connected and automated vehicles aim to improve the comfort and the safety of the driver and passengers. To this end, car manufacturers continually improve actual standardized methods to ensure their customers safety, privacy, and vehicles security. However, these methods do not support fully autonomous vehicles, linkability and confusion threats. To address such gaps, we propose a systematic threat analysis and risk assessment framework, SARA, which comprises an improved threat model, a new attack method/asset map, the involvement of the attacker in the attack tree, and a new driving system observation metric. Finally, we demonstrate its feasibility in assessing risk with two use cases: Vehicle Tracking and Comfortable Emergency Brake Failure.","Title: A Unified Framework of Clustering Approach in Vehicular Ad Hoc Networks.\nYear: 2018\n\nAbstract: Effective clustering algorithms are indispensable in order to solve the scalability problem in vehicular ad hoc networks. Although current existing clustering algorithms show increased cluster stability under some certain traffic scenarios, it is still hard to address which clustering metric performs the best. In this paper, we propose a unified framework of clustering approach (UFC), composed of ...","Title: Slicing-Based Offloading in Vehicular Edge Computing\nYear: 2021\n\nAbstract: Vehicular edge computing (VEC) provides an environment for offloading tasks from vehicles. Indeed, the advantage through VEC is to push power computational and storage capacities at the edge nodes near the vehicles to handle the enormous resources required by some applications. On the other hand, in order to manage efficiently these resources, it would be necessary to partition them into several p...","Title: An Analytical Model of Bluetooth Performance Considering Physical and MAC Layers’ Effects\nYear: 2021\n\nAbstract: This paper presents an analytical model for the average Packet Error Rate (PER) of Bluetooth in Basic Rate (BR) mode. The effects of the physical layer and the MAC layer are taken into account. A Nakagami-m block fading is considered to take into account the effects of wireless channel fading. A Gaussian Frequency Shift Keying (GFSK) modulation scheme is used. Also, Forward Error Control (FEC) cod...","Title: Dynamic Graph Convolutional LSTM application for traffic flow estimation from error-prone measurements: results and transferability analysis\nYear: 2021\n\nAbstract: The technological advances in the transportation and automotive industry led to the use of new types of sensing systems more cost-effective and adapted to large-scale dense deployment. Those sensing techniques allow continuously gathering traffic measurements times series in different geospatial locations. The accuracy of the obtained raw measurements is often hindered by different factors related...","Title: Dynamic Graph Convolutional LSTM application for traffic flow estimation from error-prone measurements: results and transferability analysis\nYear: 2021\n\nAbstract: The technological advances in the transportation and automotive industry led to the use of new types of sensing systems more cost-effective and adapted to large-scale dense deployment. Those sensing techniques allow continuously gathering traffic measurements times series in different geospatial locations. The accuracy of the obtained raw measurements is often hindered by different factors related to the sensing environment and the sensing process itself and thus fail to capture the short-term traffic variations crucial for real-time traffic monitoring. In this paper, we propose the DGC-LSTM model for area-wide traffic estimation from error-prone measurements time series. The backbone of the DGC-LSTM model is a graph convolutional Long Short Term Memory model with a dynamic adjacency matrix. The adjacency matrix is learned and optimized during the model training. The adjacency matrix values are estimated from the set of contextual features that impact the dynamicity of the dependencies in both the spatial and temporal dimensions. Experiments on a realistic synthetic labelled Bluetooth counts dataset is used for model evaluation. Lastly, we highlight the importance of transfer learning methods to improve the model applicability by ensuring model adaptation to the new deployment site while avoiding the extensive data-labelling effort.","Title: Joint Content-Prefetching, Transmission Scheduling, and Rate Adaptation in Vehicular Networks\nYear: 2022\n\nAbstract: Content prefetching at road side units (RSUs) in vehicular networks can improve users’ experience by reducing the average data access latency. Prefetching algorithms proposed in the literature usually rely on a fixed modulation scheme, that corresponds to the lowest possible data rate for RSU-to-vehicles transmission. As a consequence, the network bandwidth is often inefficiently used. In this art...","Title: Network slicing with load-balancing for task offloading in vehicular edge computing\nYear: 2022\n\nAbstract: The support of edge computing for vehicular technologies gained increasing momentum with 5G to fulfill efficient offloading tasks from vehicles towards the edge nodes. Accordingly, vehicles demanding powerful computation and large storage resources will be directed to communicate with the nearest edge computing nodes hosted at a wireless 5G new generation nodes (gNBs) or a road side units (RSUs). To efficiently utilize the edge nodes' resources, network slicing and load-balancing features can greatly help in that, therefore, this paper proposes an algorithm for Vehicular Edge Computing (VEC) with network slicing and load-balancing based on resources utilization, denoted as VECSlic-LB, specifically dedicated for offloading tasks from vehicles to edge nodes at gNBs or RSUs. The algorithm can holistically view and manage the whole network, and use network function virtualization framework to manage the data plane. VECSlic-LB can handle a mix of slicing configurations, capable of balancing the loads between various slices per node, and can support multiple edge computing nodes. Several simulations were conducted comparing the performance of the proposed algorithm to the optimal solution, resulting on very close acceptance ratios as the optimal solution, and also was evaluated against a recent reference algorithm, providing more efficient resource utilizations ratios, saving up to 48% of the resources better than the state-of-art algorithm. (c) 2021 Elsevier Inc. All rights reserved.","Title: Blockchain-Based Collaborative Certificate Revocation Systems Using Clustering\nYear: 2022\n\nAbstract: Despite the decisive contribution of intelligent transport systems in road safety, they also open new vulnerabilities to cyber-attacks, particularly vehicle position-linked attacks. For that reason, centralized systems are becoming increasingly vulnerable to the growth of the connected-vehicle fleets as it becomes more challenging to revoke certificates in real-time. We have proposed a new method that integrates a decentralized, collaborative system to meet these challenges. This method efficiently allows Blockchain integration for vehicular network's cyber security by dynamically creating communities to revoke malicious vehicles in real-time. This article presents analytical models of the system of real-time revoking certificates and examines our solution's impact on two important types of attacks in V2X communications, Sybil and the faking position attacks. Our experiments using real V2X hardware demonstrated the feasibility and benefits of real-time revocation via vehicle communities. The results were obtained from consensus implementation in a vehicular network comprising three communicating vehicles and a single roadside unit. In parallel, simulations showed feasibility in large-scale communications. As a result, the exposure and detection times of our solution meet real-time requirements.","Title: Toward Multiple-Phase MDP Model for Charging Station Recommendation\nYear: 2022\n\nAbstract: There is an increasing need for charging station recommendation to minimize the overall charging time for electric vehicles and balance load for the charging stations. To grant this need, we model the recommendation problem as a Markov Decision Process (MDP) problem. However, the traditional MDP model has the issue of ‘curse of dimensionality’. To address this issue, we propose an extension of MDP: multiple-phase MDP, in which the state transition of MDP is decomposing into several phases, so as to reduce the state space and state transition complexities. This is done by introducing two states other than the normal state defined in MDP: post decision state and intermediate decision state. Then, we propose an online learning based algorithm to solve the formulated multiple-phase MDP model. Thanks to the reduced complexities of the state space and state transition, the proposed online algorithm can converge fast. By comparing to other recommendation mechanisms, such as game theory based recommendation and Q-learning based recommendation, our simulation evaluation demonstrates that our proposition can bring good performance."],"string":"[\n \"Title: A Performance Comparison of Position-Based Routing Approaches for Mobile Ad Hoc Networks\\nYear: 2007\\n\\nAbstract: In this work we present a performance comparison study between SIFT (Simple Forwarding over Trajectory), an innovative and scalable trajectory-based approach, and DREAM (Distance Routing Effect Algorithm for Mobility), a stable, largely tested position-based scheme. In the literature, the latest studies indicate that control overhead is the most important drawback that routing protocols must face. Classical ad hoc routing schemes do not perform well in MANETS (Mobile Ad hoc Networks) because they were not designed to handle efficiently mobility handicaps. Position-based forwarding techniques perform better in highly dynamic scenarios, reducing control overhead consequences, but there may be some highly dynamic scenarios where they do not perform efficiently. Trajectory-based forwarding protocols solve the overhead problem and, thus, they perform efficiently in MANETS. Our study demonstrates that SIFT performs better than DREAM concerning delivery ratio, control overhead and route length in terms of number of hops. Its main handicap could be, a priori, the delivery delay. However, even if delay may be high in SIFT, control overhead may also causes even higher delivery delay in DREAM.\",\n \"Title: A Layer-2 Multi-Hop Authentication and Credential Delivery Scheme for Vehicular Networks\\nYear: 2008\\n\\nAbstract: In this paper we introduce a novel security architecture and security mechanisms for vehicular networks environments. Our approach provides a layer-2 multi-hop authentication and credential delivery scheme between vehicles and the network operator authentication server. We analyze the performance of the proposed solution through extensive simulations, showing the success of our scheme (compared to the legacy single-hop scheme) in providing a robust and efficient authentication and credential delivery to vehicles. Based on the obtained performance analysis, we derive some guidelines aiming to optimize our solution under various vehicles densities.\",\n \"Title: Exploiting power-law node degree distribution in Chord overlays\\nYear: 2009\\n\\nAbstract: In this paper, we propose to extend the topology of Chord to a bidirectional graph to provide a super-peer based lookup algorithm and a scalable broadcast search support. We consider routing algorithms for a bidirectional variant of Chord network and show how the resulting structure extends the search region and provides an efficient resource lookup service at a very little additional cost.\",\n \"Title: A Distributed Hybrid Channel Selection and Routing Technique for Wireless Sensor Networks.\\nYear: 2011\\n\\nAbstract: In this paper, we propose Well-Connected Dominating Set Channel Assignment (WCDS - CA), a distributed hybrid algorithm that uses a well-connected dominating set to perform a selection of communication channels in wireless sensor networks in such a way that the number of channels used and interference among sensor nodes remains minimal. Since the network topology allows each sensor node to be equipped with several radio interfaces, a set of parents and leaves are statically assigned to a single fixed channel. The routers are assigned to several orthogonal channels using the corresponding radio interfaces in such a way that they can switch dynamically to the static channels of parent nodes in order to minimize network interference. The tree based on Breadth-First Search is built out from the sink, with the result that the shortest between each sensor and the sink is established. This allows the data to be efficiently propagated from parent to router to parent towards the sink in order to reduce the number of individual transmissions. We compare the results obtained with those for a single channel by taking the common links used by each node on each channel and packets transmitted as performance criteria, and show that our proposal gives better results in dense wireless sensor networks.\",\n \"Title: A New Access Control Solution for a Multi-Provider Wireless Environment\\nYear: 2005\\n\\nAbstract: The fundamental goal in future 4G mobile multi-service networks is to provide an efficient mobile computing environment. We presume that future terminals will be equipped with multiple heterogeneous wireless interfaces. We want to enable each user to seamlessly move between different providers' networks. Besides seamless roaming, a key consideration is also devoted to quality-of-service provision. In this article, we propose a model and an architectural framework for supporting quality of service in the context of interconnected multi-provider wireless systems. The proposed integrated COPS-based management and RADIUS-based access control architecture will allow providers to offer multimedia services while optimizing the use of the underlying network resources. We suggest new concepts and protocols to provide solutions to these challenges and describe the French national research project named MMQoS aiming on building such future networks.\",\n \"Title: Exploiting routing unfairness in DHT overlays\\nYear: 2009\\n\\nAbstract: Peer-to-Peer overlays have become a popular paradigm for building distributed systems, aiming to provide resource localization and sharing in large-scale networks. To design an overlay network, the first step is to choose an overlay topology connecting all the overlay nodes. Many proposed distributed hash table schemes for peer-to-peer network are based on some traditional calculated interconnection topologies. In this paper, we propose to extend the DHT topology to a bidirectional graph to provide a super-peer based lookup algorithm and a scalable resource localization support. We consider bidirectional routing algorithms and show how the resulting unfair routing structure extends the search region and provides an efficient resource lookup service at a very little additional cost.\",\n \"Title: Performance Comparison Of Multipath Reactive Ad Hoc Routing Protocols\\nYear: 2008\\n\\nAbstract: The recent proliferation of wireless devices extends the scope of Mobile Ad hoc NETworks (MANETs) applications beyond the military domain to include civil and commercial application scenarios. Since MANETs are composed of mobile terminals with limited resources, guaranteeing their security remains an unsolved and motivating challenge. Due to advantageous features like infrastructureless and spontaneous deployment, MANETs offer an opportunity to set up temporary, dynamic and local networks for low cost. However, some of their characteristics like unreliability of wireless links, dynamic topology, and absence of underlying infrastructure raise serious problems which become critical when security is also considered. Multipath routing scheme enhances the robustness of routing protocols and offers a mean to mitigate networks mobility impact and node misbehaviors. In this paper we compare the performances of five multipath routing protocols: three node-disjoint multipath routing protocols and two routing protocols based on a Untrusted Node Disjoint (UND) path scheme. Comparisons between these protocols highlight the improvements raised by the UND scheme under different attack configurations.\",\n \"Title: A performance comparison of multicast routing protocols in ad hoc networks.\\nYear: 2003\\n\\nAbstract: Multicast Routing in Mobile Ad hoc NETworks (MANETs) is a recent research topic. In this paper, we present a performance study of three multicast protocols: ODMRP, ADMR, and SRMP. Source Routing-based Multicast Protocol (SRMP) is a new on-demand multicast routing protocol that applies a source routing mechanism and constructs a mesh to connect group members. The strength of SRMP lies on its nodes selection criteria during mesh construction. Instead of using the shortest path as most of the other protocols, SRMP provides paths in terms of connectivity strength, higher battery life, and links' availability. A performance comparison with ODMRP and ADMR shows that SRMP provides better route lifetime and battery lifetime.\",\n \"Title: Hybrid architecture for resource reservation in IP based mobile networks\\nYear: 2010\\n\\nAbstract: User mobility management is one of the important components of mobile multimedia systems. In an IP-based mobility case, a mobile node should be able to seamlessly obtain reserved resources after handover to a new access router. This is essential for both service continuity and quality of service assurance. In this paper, we introduce a hybrid architecture which allows a mobile node to seamlessly obtain reserved resources from its new location (seamless reservation), as well as to quickly release obsolete resources along the old path. In this architecture, reservation on access networks is performed by using path-decoupled approach, while path-coupled approach is used on backbone networks. Moreover, instead of using sender-initiated or receiver-initiated approach, mobile-node-initiated approach is used in this architecture to further improve reservation performance. In our performance analysis, we analyze advance reservation delay and release delay, as well as reservation underutilization.\",\n \"Title: Adaptive path energy conserving routing in MANETs\\nYear: 2005\\n\\nAbstract: The specific features of mobile ad hoc networks (MANETs) impose new requirements for routing protocols. The aim of this paper is to present an approach that enhances routing performance by integrating ad hoc related characteristics. We propose a loop-free adaptive path energy conserving scheme which attempts to minimize both routing and storage overhead in order to efficiently provide robustness to host mobility, adaptability to wireless channel fluctuations and optimization of network resources use in large-scale networks. The strength of our scheme, based on source routing approach, named Energy Conserving Dynamic Source Routing (EC-DSR), is to handle network state related constraints such as node's energy consumption, links' availability and paths' quality. The performance of the proposed scheme is evaluated via simulation and is compared to DSR protocol. Better results are obtained with EC-DSR in terms of control overhead. Furthermore, EC-DSR shows significant improvements in delay and forwarding efficiency for large scalable networks.\",\n \"Title: Prioritizing and Enhancing Vehicular Networks Authentication Process Using DSRC Channels Diversity\\nYear: 2008\\n\\nAbstract: In this paper we introduce a prioritization scheme for enhancing the performance of the authentication process in vehicular networks using Dedicated Short Range Communications (DSRC). We consider the authentication as a service that should be required by each user in order to gain access to the network and to the offered services. Instead of using a unique channel to transmit the messages of the authentication service as in the case of the legacy DSRC model, our scheme extends this latter through exploiting the various DSRC channels based on a channel sensing approach that aims to prioritize the transmission of the authentication messages (with respect to the transmission of other DSRC services messages of the same priority as the authentication service). We implemented our proposed solution under the GrooveNet vehicular network simulator, where we analyze its performance impact on a previously proposed vehicular network authentication mechanism. Extensive simulations show the success of our proposed scheme in providing a more efficient and robust authentication in the presence of other services' traffics.\",\n \"Title: Resaco: An Open And Programmable Multi-Domain Platform For Cooperative And Auto-Configurable Networks\\nYear: 2004\\n\\nAbstract: This paper presents a set of studies and proposals related to cooperative, auto-configurable and adaptive networks. It summarizes some extensions and experiments performed within the RESACO project. The objective of this project is to propose viable architectures and tools that enable and enhance Quality-of-Service (QoS), mobility, service discovery and security aspects over multidomain and heterogeneous networks. The proposed extensions are based on the use of programmable software-based edge routers and access points. Additional features that enable are adaptability, auto-configuration and cooperation are experimented.\",\n \"Title: Mobility And Qos Of 802.11 And 802.11e Wireless Lan Standards\\nYear: 2009\\n\\nAbstract: Quality of service is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN are the most widely used WLAN standards today, and the IEEE 802.11e quality of service enhancement standard exists and introduces quality of service support for multimedia applications. This paper compares the propositions of standard IEEE 802.11e with the standard IEEE 802.11 without quality of set-vice, a simulation of these standards is performed by using the network simulator simulator. We test also the mobility and the roaming of stations. A discussion is presented in detail using simulation-based evaluations and we let its confirm the quality of service of IEEE 802.11 e compared to IEEE 802.11, but we have detected some weaknesses of 802.11e. It starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate Of weight of queues, so there is an unbalance enters the flows with high priorities.\",\n \"Title: Design of New Aggregation Techniques for Wireless Sensor Networks\\nYear: 2010\\n\\nAbstract: This paper compares different alternative aggregation techniques for Wireless Sensor Networks Optimization based on tree construction. The main idea is to efficiently elect parent nodes responsible of data aggregation according to their connectivity degree. Thus, the quantity of data transmitted on the network remains minimal during the transfer from all sensors towards the sink. Simulations have shown that our new approach provides a better performance than existing techniques such as BFS, DFS and flooding, especially in terms of quantity of data packets transmitted from all sensor towards the sink.\",\n \"Title: Analytical study of intradomain handover in multiple-mobile-routers-based multihomed NEMO networks\\nYear: 2010\\n\\nAbstract: The need to stay connected to the Internet ''anytime'' and ''anywhere'' is becoming more and more required in the recent years with the development of wireless networks. The NEMO basic support protocol was developed to grant the Internet connection for an entire mobile network, like vehicle or aircraft network. In NEMO a Mobile Router manages the mobility of the entire network on behalf of the other nodes in order to reduce the overhead of signaling messages. The critical part of mobility support is to reduce the handover latency, particularly when a Mobile Router is not reachable. This handover period degrades the performance of most delay sensitive applications. Referring to our proposition for NEMO handover improvement which is conceived for multiple-mobile-routers-based multihomed NEMO network, we find out a mathematical model to study the intradomain handover performance. We derive the mathematical model to analyze interruption interval (the time interval during which none of mobile routers can transport packets) during the intradomain handover. We study the impact of varying critical parameters, like vehicle speed, overlapping coverage distance, distance between mobile routers, and scanning frequency. The obtained results reveal that the seamless handover can be achieved if network configuration parameters are correctly chosen.\",\n \"Title: Power-law chord architecture in P2P overlays\\nYear: 2008\\n\\nAbstract: In this paper, we propose to extend the topology of Chord to a bidirectional graph to provide a super-peer based lookup algorithm and an efficient resource localization service at a very little additional cost.\",\n \"Title: On Analyzing the Potential of a Layer-2 Multi-hop Authentication and Credential Delivery Scheme for Vehicular Communications\\nYear: 2009\\n\\nAbstract: In this paper we introduce a new security architecture and security mechanisms for vehicular networks providing a layer-2\\n multi-hop authentication and credential delivery scheme between vehicles and the network operator authentication server. We\\n present a performance analysis of the proposed solution under various vehicles and Access Points (APs) densities, showing\\n the potential of our scheme in providing a more efficient, robust and scalable authentication and credential delivery to vehicles\\n when compared against the classical single-hop scheme.\",\n \"Title: Advance reservation optimization in IP-based mobile networks\\nYear: 2009\\n\\nAbstract: To provide continuous Quality-of-Service in mobility scenarios, advance reservation should be performed at the location to which a mobile node is expected to move. However, since these reserved resources in advance are not used before the arrival of the mobile node (or only can be used by best effort flows), resource waste is involved. The issue how to minimize this waste is addressed in this paper. We propose, firstly, that advance reservation is triggered when the mobile node's distance to the edge of its serving access router's coverage area is optimal. A mathematical model is developed to calculate this optimal distance. In our analysis, we investigate the impact of some parameters on the optimal distance. Second, we demonstrate that path-decoupled reservation technique can provide better performance than path-coupled reservation when being adopted for mobility scenarios, because path-decoupled reservation incurs much less setup delay. The impact of the reservation delay on session's success probability and access router's capacity is analyzed\",\n \"Title: Event Based Mobility Model for Subway Scenarios\\nYear: 2007\\n\\nAbstract: High cost and complexity of Mobile Ad hoc NETworks (MANETs) testbeds let simulation as the best solution to experiment MANETs protocols and applications. Thus improving current simulation tools become crucial to provide valuable results. Mobility and propagation models are key element to realistically simulate user's behaviour and wave propagations and therefore assure the validity of the simulations results. Unfortunately, accurate mobility models are complex and consider a wide range of parameters. Indeed to reflect reality every detail which may modify the mobility of users has to be included in the models. Consequently most of the realistic simulations models are not scalable and involve excessive computation time. Furthermore, these models are very generic and fail to capture the impact of event in real environments. In this paper we present an accurate Subway Mobility Model which requires only few parameters. Moreover the simulated environment represents an application prolific context which can easily be set up. Finally we provide average simulation execution time for large networks and a comparison with the Random Waypoint model\",\n \"Title: RVP: A New Policy for Aggregate Reservation\\nYear: 2008\\n\\nAbstract: Reservation aggregation provides scalability to the IETF Integrated Services (IntServ) by reducing the high number of states stored at internal routers and the number of signalling messages processed at these routers. However, the latter benefit will be lost if the bandwidth of aggregate reservation changes frequently. Hence, previous works either hold resource requests during a waiting period before sending a single aggregate reservation for all received requests, or reserve maximum resources which will be requested in the following period. However these works involve an assumption of arrival distribution of resource requests. In this paper, we design a policy for enhancing the reservation aggregation performance, which is independent of arrival distribution. From the results of simulation, we observe that this policy outperforms other policies.\",\n \"Title: Opportunistic Trajectory-Based Routing For V2v Communications\\nYear: 2011\\n\\nAbstract: In this paper, we propose enhanced Simple Forwarding over Trajectory (eSIFT), a novel opportunistic trajectory-based routing protocol for Vehicular Ad hoc Networks (VANETs), based on Simple Forwarding over Trajectory (SIFT). eSIFT is designed to operate in highly dynamic vehicular networks for data dissemination. eSIFT presents advantages such as no discovery step and low overhead. We also present performance evaluation results of eSIFT, in comparison to SIFT. Simulations show that eSIFT improves SIFT, in particular in term of delay, and slightly in term of hop count and packet delivery ratio.\",\n \"Title: Performance Evaluation of Hybrid Channel Assignment for Wireless Sensor Networks\\nYear: 2012\\n\\nAbstract: Data transmission in Wireless Sensor Networks (WSNs) is physically constrained by interference, throughput, latency and many other physical phenomena. We propose a distributed hybrid algorithm to perform the selection of communication channels in such a way that overall throughput, latency, energy and overhead are improved. A tree structure is built out from the sink, in order to elect sensors with the highest degree of connectivity as parents, and sensors with the lowest degree of connectivity as leaves. A set of parents and leaves are assigned to a single fixed channel. Specific sensors, called mediators, are assigned to several orthogonal channels. So, they can switch dynamically to the static channels of parents for collecting the data. This allows the data to be efficiently propagated in parallel on multiple channels from parent to mediator to parent towards the sink. We compare the results obtained with those for single and multiple channels by taking sink throughput, broadcast latency, energy consumption and routing overhead as performance criteria. We show that our method provides better results.\",\n \"Title: CATS: An adaptive traffic signal system based on car-to-car communication.\\nYear: 2013\\n\\nAbstract: Traffic signal controls play an important role in regulating vehicular flow at road intersections. Traditional systems are not capable of adjusting the timing pattern in accordance with vehicular demand. This results in excessive delays for road users. Hence it is necessary to develop dynamic systems that can adjust the timing patterns according to traffic demand. In this paper, the design and implementation of an adaptive traffic signal control system based on car-to-car communication is presented. Also, a clustering algorithm is defined which will assist in estimating the density of vehicles approaching an intersection. The cycle time, which is calculated using the estimated density of vehicular traffic, helps in reducing both the waiting time for vehicles at intersections and queue length. It is also shown that the proposed solution is collision free at intersections. The proposed system is compared with a classic pre-timed system and an adaptive fuzzy logic system. The simulations also show that the data convergence time and the communication delay between vehicles and traffic signals do not compromise the efficiency of the system.\",\n \"Title: Aggregation methods for integrated services\\nYear: 2011\\n\\nAbstract: Reservation aggregation provides scalability to the IETF Integrated Services (IntServ) by reducing the high number of states stored at internal routers and the number of signaling messages processed at these routers. However, in the case of frequent joining and leaving of individual flows, the latter benefit will be lost due to frequent adjustment of aggregation size. In this paper, to reduce aggregation adjustment frequency, we focus on investigating two critical parameters: aggregation size and the lower threshold. We propose two policies to find out the optimal values of these criteria. One policy called Two Bounded operating Policy (TBP) is parameter-based policy and the other called Resource request Variance Policy (RVP) is measure-based policy. The calculation of these optimal values considers three costs: underutilization cost, signaling cost and holding cost. In our evaluation study, we compare the proposed two policies with two others, Temporal Operating Policy (TOP) and Cardinal Operating Policy (COP). This study shows that our mechanisms outperform the previous propositions in terms of cost and blocking ratio. Copyright © 2011 John Wiley & Sons, Ltd.\",\n \"Title: Performance analysis of position-based routing approaches in VANETS.\\nYear: 2007\\n\\nAbstract: This article presents a performance analysis between two location-based routing protocols: SIFT (SImple Forwarding over Trajectory), a novel, scalable, spatial-aware, trajectory-based approach, and DREAM (Distance Routing Effect Algorithm for Mobility), a stable, largely tested position-based scheme. The study was accomplished under a realistic urban mobility model for VANETS (Vehicular Ad hoc NETworks), within a highly deployed evaluation network of up to 1000 nodes. Classical ad hoc routing schemes do not perform well in VANETS because they were not designed to handle efficiently mobility handicaps. Position-based techniques perform better in dynamic scenarios, but in some highly dynamic scenarios, like VANETS, they do not always perform efficiently. Trajectory-based protocols perform more efficiently in VANETS since they are spatial-aware. We demonstrate that SIFT performs better than DREAM in a realistic VANET scenario concerning delivery ratio, control overhead, delivery delay, and route length.\",\n \"Title: Cooperation Optimized Design for Information Dissemination in Vehicular Networks using Evolutionary Game Theory\\nYear: 2013\\n\\nAbstract: We present an evolutionary game theoretic approach to study node cooperation behavior in wireless ad hoc networks. Evolutionary game theory (EGT) has been used to study the conditions governing the growth of cooperation behavior in biological and social networks. We propose a model of node cooperation behavior in dynamic wireless networks such as vehicular networks. Our work is motivated by the fact that, similar to existing EGT studies, node behavior in dynamic wireless networks is characterized by decision making that only depends on the immediate neighborhood. We adapt our model to study cooperation behavior in the context of information dissemination in wireless networks. We obtain conditions that determine whether a network evolves to a state of complete cooperation from all nodes. Finally, we use our model to study the evolution of cooperation behavior and its impact on content downloading in vehicular networks, taking into consideration realistic network conditions.\",\n \"Title: ScatterPastry: An Overlay Routing Using a DHT over Wireless Sensor Networks\\nYear: 2007\\n\\nAbstract: Using Distributed Hash Tables (DHTs) over ad-hoc wireless sensor networks (WSNs) has gained a lot of attention in the research arena in last years. In WSN's world, the most important issue in routing is to gather the routed information coming from sensor nodes to the sink node regardless of the identity of the donating node. The problem in this context is to locate efficiently the sensor node, which holds the data item with the minimum number of intermediate nodes to save network energy. DHTs based on the Internet are used for this purpose. This paper presents a ScatterPastry platform based on Pastry DHT as an overlay routing platform for distributed applications over WSNs using Scatterweb nodes, a real-world wireless sensor platform.\",\n \"Title: VANET Inherent Capacity for Offloading Wireless Cellular Infrastructure: An Analytical Study.\\nYear: 2014\\n\\nAbstract: Due to the high user traffic demand increase, offloading cellular traffic through other kinds of networks, such as Wi-Fi hotspots and femtoCells has been highly studied. In this paper, we investigate upon the possibility to use Vehicular ad hoc Networks (VANETs) for the offloading the cellular infrastructure. We present an analytical study based on an optimization problem formulation where the aim is to select a maximum target set of flows that could be routed to the destination downloader node through the VANET network. The offloading decision considers the vehicular link availability, channel load by considering medium contention, vehicle to vehicle link quality and the link connectivity duration between the VANET node and the road side unit. Simulation results of our analytical approach show that the data offloading fraction is closely affected by the data volume of the flows, the channel load and by the link quality. Results show also that the offload of best effort data traffics could reach 100 percent for low data volumes.\",\n \"Title: A global security architecture for operated hybrid WLAN mesh networks\\nYear: 2010\\n\\nAbstract: Hybrid Wireless Mesh Network (HWMN) is a new wireless networking paradigm. Unlike traditional wireless networks, in HWMNs, hosts may rely on each other to keep the network connected. Operators and wireless internet service providers are choosing HWMNs to offer Internet connectivity, as it allows fast, easy and affordable network deployments. One main challenge in design of these networks is their vulnerability to security attacks. In this paper, we investigate the main security issues focusing on the most vulnerable part of the hybrid WLAN mesh infrastructure which concerns the ad hoc network part. Through our proposed architecture, Security Architecture for Operator's Hybrid WLAN Mesh Network (SATHAME), we identify the new challenges and opportunities posed by this emerging networking environment and explore approaches to secure users, data and communications. From the analysis of strengths and weaknesses of secured routing protocols, we designed a new robust routing structure called MacroGraph (MG). MG structure is extracted from the mesh ad hoc network for each communication to be established between a source and a destination. Especially, MG is a robust structure based on node-disjoint path routing scheme and dynamic trust management that can be adapted to respond to applications' security requirements. We present a performance analysis of our efficient, robust and scalable multipath reactive secured routing protocol. We investigate the behavior of our proposed scheme under two attack scenarios: Packet Dropping and Route Error attacks in dense network configurations.\",\n \"Title: An Efficient Scalable Trajectory Based Forwarding Scheme for VANETs\\nYear: 2010\\n\\nAbstract: The past few years have seen an increasing interest in the development of vehicular ad hoc networks resulting in many routing protocols proposals. Scalability issues in such networks are attracting increasing attention these days. To improve data delivery performance in large scale networks, we propose SIFT, a trajectory based routing scheme that requires sparse infrastructure and rely on low quality information. It merely uses the trajectory and the location of the last node that forwarded the packet to forward a data packet from a source to a destination. SIFT is evaluated against DREAM, a well-known routing protocol from the literature through realistic simulations using Omnet++. Simulation results demonstrate that under dense deployment, using a realistic mobility model scenario, the proposed scheme performs better in terms of delivery ratio, end-to-end delay and route length.\",\n \"Title: Symmetric replication for efficient flooding in DHTs\\nYear: 2008\\n\\nAbstract: To support complex queries and broadcast in DHTs, we propose an algorithm for an effective flooding that we implement and compare in a Chord DHT. We use flooding and replication that exploit structural constraints to achieve lower overhead and higher reliability.\",\n \"Title: ASMA : Towards Adaptive Secured Multipath in MANETs\\nYear: 2006\\n\\nAbstract: As they are used to create open communities, Mobile Ad hoc NETworks (MANETs) are not favourable environments to establish trust, which is necessary to provide security. Multipath routing mechanisms within infrastructureless networks environment seems appropriate and useful to enhance security protection. In fact, the level of trust can be increased so as many of potential security attacks are detected, revealed and stopped. Nevertheless an excessive control overhead is always generated. In this paper, we propose a global framework that integrates a set of concepts and mechanisms aiming at enhancing security in highly dynamic decentralized ad hoc networks. Our solution focuses on authentication, routing securing, trust management with reliable estimation of trust. A large panoply of attacks are prevented using our various mechanisms.\",\n \"Title: MA-WATM: a new approach towards an adaptive wireless ATM network\\nYear: 1999\\n\\nAbstract: In a cellular multimedia network like wireless ATM (WATM), self control seems primordial. Our new approach is based on the application of DAI (distributed artificial intelligence) techniques in order to build a self-adaptive network within random non-uniform traffic conditions. Attempting to achieve a high network capacity in terms of resource allocation and air interface BER (bit error rate), we propose to apply intelligent agent features to enhance the architecture of WATM systems. In fact, the intelligent platform MA-WATM (multi-agent wireless ATM) is used to provide a flexible integration of the multi-agent technique in wireless entities, BSs (base stations), MSs (mobile stations) and MSCs (mobile switching centers). Two applications are investigated and explored by simulations in order to bear out the feasibility of the multi-agent approach.\",\n \"Title: A construction scheme for scale free DHT-based networks\\nYear: 2009\\n\\nAbstract: In this paper, we propose PowerDHT, a novel scheme to extend the classic DHT-based overlay to a network with scale free-like properties. PowerDHT has a distributed rewiring method to improve the structure of the overlay network to a power-law-like graph. Our scheme is characterized through minimal, typically local-only, changes. Through simulations, we show that our proposal constructs an overlay network with an extended peer's neighborhood knowledge and a reduced network diameter at no additional cost and that it supports a more effective flooding e.g. for generic search.\",\n \"Title: Effect of Sink Location on Aggregation Based on Degree of Connectivity for Wireless Sensor Networks\\nYear: 2011\\n\\nAbstract: In this paper we study the effect of sink location on aggregation through many random Wireless Sensor Network topologies based on tree construction. The key idea is to build the tree out from the sink, taking into account node's degree of connectivity, in order to elect the node with the highest degree of connectivity as a parent, and the node with lowest degree of connectivity as a leaf. The shortest path between each sensor and the sink is established. Thus, the data transmitted on the network remains minimal and will propagate from parent to parent towards the sink. We then select the best location of the sink in order to obtain the minimal number of packets transmitted from all sensors towards the sink, and the maximum number of leaves. Simulations have shown that our new method provides promising results that are better than existing algorithms such as BFS, DFS and flooding.\",\n \"Title: An efficient qos based gateway selection algorithm for VANET to LTE advanced hybrid cellular network\\nYear: 2012\\n\\nAbstract: In this paper, we address the gateway selection issue in a hybrid system composed of a VANET network and a 4G LTE Advanced infrastructure. The VANET network is structured via a clustering scheme. Our algorithm is based on a multi-criteria and QoS related attributes approach used to make a decision of the appropriate gateway that might be used to connect a source vehicle to the LTE Advanced infrastructure. Considered criteria for making the decision include load, Received Signal Strength and Link Connectivity Duration of the cluster head and other candidate gateways. Simulation results demonstrate that our algorithm makes efficient decisions for electing the appropriate gateway with the best VANET and infrastructure features.\",\n \"Title: Performance evaluation of replication strategies in DHTs under churn\\nYear: 2007\\n\\nAbstract: This paper presents a comparative analysis of replication algorithms for DHT (Distributed Hash Table) architectures. These algorithms are applicable to all existing structured peer-to-peer systems, and can be implemented on top of any DHT. The performance of these algorithms is examined using emulation through virtualization. Significant differences are identified in terms of delays, control overhead, success rate, and overlay route length.\",\n \"Title: Energy Consumption Routing for Mobile Ad Hoc Networks\\nYear: 2003\\n\\nAbstract: The specific features of mobile ad hoc networks (MANETs) impose new requirements for routing protocols. The aim of this paper is to present an approach that enhances routing performance by integrating ad hoc related characteristics. We propose a loop-free adaptive path energy conserving scheme which attempts to minimize both routing and storage overhead in order to provide efficiently robustness to host mobility, adaptability to wireless channel fluctuations and optimization of network resources use in large-scale networks. The strength of our scheme, based on source routing approach, named Energy Conserving Routing (ECR), is to handle network state related constraints such as node's energy consumption, link availability and path quality. The performance of the proposed scheme is evaluated via simulation and is compared to DSR protocol. Better results are obtained with ECR in terms of path lifetime, forwarding efficiency, delay, and total overhead.\",\n \"Title: Symmetric routing in DHT overlays\\nYear: 2011\\n\\nAbstract: In this paper, we propose to extend the DHT topology to a bidirectional graph to provide a super-peer based lookup algorithm and a scalable search support. We consider routing algorithms for a bidirectional variant of the DHT network and show how the resulting structure extends the search region and provides an efficient resource lookup service at a very little additional cost.\",\n \"Title: Mini-sink mobility with diversity-based routing in wireless sensor networks\\nYear: 2011\\n\\nAbstract: The performance of Wireless Sensor Networks (WSNs) is constrained by congestion, latency, data loss and other phenomena. In this paper, we propose a model based on the use of Mini-Sinks (MSs), each with considerable storage capacity, instead of a single sink for collecting the data. The idea is that one or more MS are mobile and move according to an arbitrary mobility model inside the sensor field to collect data within their coverage areas and forward it towards the sink. Energy Conserving Routing Protocol (ECRP), based on route diversity, is implemented in MSs and sensors in order to optimize the transmission cost of the forwarding scheme. A set of multiple paths between MSs and sensors is generated to reduce local congestion phenomena and to distribute the global traffic over the entire network. Since a topology incorporating MSs changes constantly due to their mobility, we analyze the impact of global connectivity for a given WSN. Simulations were performed in order to validate the performance of our model. We compare the results obtained with those for a single static sink, and show that our model gives better results in terms of lower congestion, energy consumption and broadcast latency.\",\n \"Title: LTE Advanced Relaying Standard: A Survey\\nYear: 2013\\n\\nAbstract: Long term evolution (LTE) Advanced is a well designed system that meets the requirements of 4G cellular systems. Its standard specification has been lately released. One of its main features is supporting relaying topology inspired from ad hoc multihop networks. This paper is a survey upon the relaying architecture of LTE Advanced standard based on 3GPP Release 10 specifications. A comparison with other relaying architectures, i.e. IEEE 802.16m and IEEE 802.11s is handled. The originality of this work is in involving comparison with multihop architecture supported by IEEE 802.11s based wireless mesh networks. Several similarities are noted and differences are pointed out.\",\n \"Title: A Fuzzy Multi-Metric QoS-Balancing Gateway Selection Algorithm in a Clustered VANET to LTE Advanced Hybrid Cellular Network\\nYear: 2015\\n\\nAbstract: Intelligent transportation systems are currently attracting the attention of the research community and the automotive industry, which both aim to provide not only more safety in the transportation systems but other high-quality services and applications for their customers as well. In this paper, we propose a cooperative traffic transmission algorithm in a joint vehicular ad hoc network-Long Term Evolution Advanced (LTE Advanced) hybrid network architecture that elects a gateway to connect the source vehicle to the LTE Advanced infrastructure under the scope of vehicle-to-infrastructure (V2I) communications. The originality of the proposed fuzzy quality-of-service (QoS)-balancing gateway selection (FQGwS) algorithm is the consideration of QoS traffic class constraints for electing the gateway. Our algorithm is a multicriteria and QoS-based scheme optimized by performing the fuzzy logic to make the decision on the appropriate gateway. Criteria are related to the received signal strength (RSS) and load of the cluster head (CH) and gateway candidates (GwCs), as well as the vehicle-to-vehicle link connectivity duration (LCD). Simulation results demonstrate that our algorithm gets better results than the deterministic scheme for gateway selection. Moreover, results show the efficiency of the FQGwS algorithm as it adapts its gateway selection decision to the cluster density and the relative velocity of the source node.\",\n \"Title: Performance analysis of a cross-layered incremental redundancy hybrid automatic repeat request (CL IR-HARQ) mechanism\\nYear: 2014\\n\\nAbstract: The performance of Hybrid Automatic Repeat reQuest (HARQ) in wireless networks has been extensively studied in recent years. Most of the HARQ performance results reported in the literature have been based on cross-layer techniques making use of Media Access Control (MAC) and physical layer information. In contrast, we present a performance analysis of a cross-layer approach that uses MAC and Internet Protocol (IP) layer information to efficiently control packet retransmissions in wireless networks. Evaluation results (using performance metrics such as packet error rate, retransmission efficiency, delay) obtained at the IP layer, using a two-state Gilbert Elliott channel model, demonstrate the significant performance improvements of the (MAC-IP) cross-layer strategy.\",\n \"Title: FQGwS: A gateway selection algorithm in a hybrid clustered VANET LTE-advanced network: Complexity and performances.\\nYear: 2014\\n\\nAbstract: In this paper, we propose a cooperative traffic transmission algorithm in a joint cellular and vehicular ad hoc hybrid network architecture. We focus on defining an algorithm aiming to select the appropriate gateway for a given source vehicle under the scope of vehicle to infrastructure communications. We consider the LTE Advanced infrastructure and propose a multi-criteria and attribute scheme named FQGwS algorithm. It is a QoS-balancing gateway selection algorithm where the decision over the gateway depends on the class of traffics to be transmitted to the infrastructure. A study of the complexity and the convergence of the algorithm is handled. Moreover, simulation results show that the packet loss is always lower than 1% and that the average delay never exceeds the delay constraint of the QoS class unlike when using the deterministic scheme.\",\n \"Title: Hybrid Handover Optimization For Multiple Mobile Routers-Based Multihomed Nemo Networks\\nYear: 2007\\n\\nAbstract: Network mobility (NEMO) provides continuous connectivity to the Internet to a mobile network when moving from one access router to another. Because of link switching delay and IP protocol operation, packets destined to a mobile network can be delayed or lost during handover period. This paper proposes a solution to improve NEMO handover performance for one kind of multihomed NEMO configuration (multiple mobile routers are located in a mobile network). To manage the traffic between access routers and mobile routers, a new control entity is introduced in order to provide low latency and no packet loss. This entity is also responsible to select the next access point for mobile router when the latter detects its movement. Using this hybrid approach, mobile router can predict a handover and has the best knowledge regarding its current location and state to initiate the handover. In addition, thanks to this entity, mobile router can, based on its current state, perform handover with different strategies, so as to improve handover performance. Despite this new mechanism, no additional function is required to mobile router in our proposition.We have carried out a comparison study of handover performance with NEMO basic protocol, and showed that our proposed scheme provides near-optimal performance in both intradomain and interdomain handover. Furthermore, certain parameters, the distance between two related MRs, the distance of overlapping area and the mobile network speed, which affect the performance of our proposition have also been studied. The results show that seamless handover can be achieved if these parameters are rightly configured.\",\n \"Title: A traffic QoS aware approach for cellular infrastructure offloading using VANETs.\\nYear: 2014\\n\\nAbstract: Offloading a part of cellular traffic through other kinds of networks, such as Wi-Fi hotspots and femtoCells represents an interesting solution for operators to cope with the high user traffic demand increase. In this paper, we propose to use the Vehicular ad hoc Networks (VANETs) for the same purpose. We present an analytical study based on an optimization problem formulation to evaluate the potential of VANET to vehicle part of the cellular traffic. The offloading decision considers several constraints related to vehicle-to-infrastructure link availability, channel and medium contention, vehicle-to-vehicle link capacity and quality, data flows volume and the link connectivity duration between the vehicle and the road side unit. Moreover, the originality of this work is the consideration of flow's service class in the offloading decision. Numerical results show that the data offloading fraction is closely affected by the data volume of the flows and by vehicular link quality. Results show also that best effort and background traffics have more priority to be offloaded than the video streaming traffics.\",\n \"Title: Information dissemination in vehicular networks via evolutionary game theory\\nYear: 2014\\n\\nAbstract: We study the problem of information dissemination in vehicular networks in this paper. Crucial information, such as traffic jamming status, is usually broadcasted inside the network. Each vehicle in the network has its own choice to either forward or drop packets for others. Although the energy consumption in general is not an issue in vehicular networks, forwarding every received packets is still not preferred as it may result in congestion in transmission. We model this problem via evolutionary game theory to investigate the cooperative behavior among vehicles. Simulation results show that, the cooperation ratio in the network is proportional to the setting of synergy factor for the evolutionary game. When nodes change their strategies according to the evolutionary game, information can be disseminated as fast as flooding scheme, while more bandwidth can be reserved.\",\n \"Title: Towards a Cooperative ITS Vehicle Application Oriented Security Framework\\nYear: 2014\\n\\nAbstract: Automotive industry is interested to ITS as it provides attractive services for connected vehicles aiming at creating a new and very promising business market. However, the security remains a major challenge for the ITS deployment as several critical threats has been identified. In this paper, we present our Cooperative ITS Vehicle Application Oriented Security Framework CIVAS for vehicle ITS stations. Our focus is given first to ITS vehicle security requirements and constraints. Then, we provide an overview of the “Defense-in-Depth” model that we adapted for securing ITS vehicle. The proposed security framework follows a modular design and is application oriented. To illustrate the interaction between designed CIVAS layers, we consider a vehicle stationary as example of a road safety use case.\",\n \"Title: A performance analysis of source routing-based multicast protocol (SRMP) using different mobility models\\nYear: 2004\\n\\nAbstract: We focus on one critical issue in mobile ad hoc networks (MANETs) that is multicast routing. In fact, optimal routes, stable links, power conservation, loop freedom, and reduced channel overhead are the main features to be addressed in a more efficient multicast mechanism. MANETs are often analyzed through simulations and their performance results depend slightly on simulation network parameters including traffic generation models, radio transmission parameters and mobility models. In this paper we evaluate the performance of our proposed multicast routing protocol, named source routing-based multicast protocol (SRMP). SRMP constructs a mesh to connect group members, providing robustness against mobility. It also provides stable paths based on links availability according to future prediction of links state, and higher battery life paths tending to power conserving. We present a full performance evaluation and analysis for SRMP under realistic conditions including, realistic movements of mobile nodes in the form of different mobility models. We present our simulation results that illustrate the importance of choosing a mobility model in the simulation. Specifically, we illustrate the effect of choosing the mobility model on the performance results.\",\n \"Title: An efficient micromobility implementation for 802.1X WLANs\\nYear: 2004\\n\\nAbstract: We analyze the implications of the integration of the current IP micromobility concepts with the 802.1X access control. We show that the independent user location tracking of IP micromobility and 802.1X provokes a significant additional handover delay and signaling load degrading the overall performance. To overcome these difficulties, we propose a system architecture which uses EAP as a general signaling protocol. We then discuss the new opportunities of our approach. Finally, we show that our system architecture can be applied in almost all access networks by exploiting the generality of the 802.1X approach.\",\n \"Title: KMS: a key management system for multi-provider interconnected Wi-Fi WLANs\\nYear: 2004\\n\\nAbstract: The fundamental goal in future mobile multiservice networks is to provide an efficient mobile computing environment which enables a user with a portable computer equipped with multiple wireless access interfaces to move seamlessly between different providers' networks. In particular, if these networks are Wi-Fi WLANs (wireless fidelity wireless local area networks), security features should be defined precisely taking into account seamless roaming. The paper considers one of the most critical security issues in Wi-Fi networks -key management. We propose a centralized approach to deal with key management in the case of an interconnection of remoted Wi-Fi networks based on using a key management server. Security goals and system architecture guidelines are outlined. In respect to the IEEE 802.11i standard, the changing of keys requires only 3 messages and the roaming situation allows the establishment of a new secure 802.11 wireless channel by exchanging only 5 messages against at least 20 messages.\",\n \"Title: Hybrid Wireless Networks: Applications, Architectures and New Perspectives\\nYear: 2006\\n\\nAbstract: With the advent and ubiquitous of wireless technology, a wide range of advanced services are expected to be supported including appealing services that currently exist in wired systems. Nevertheless, the resource constraints in wireless environment may render difficulty to realizing all the desirable services. Consequently, an infrastructure with high data rate is necessary to complement the resource constraints and to act as anchor points linking mobile nodes to other fixed networks as the Internet. Hybrid wireless networks have emerged as a promising solution, allowing mobile clients to achieve higher performance and service access in a seamless manner independent of their existence in wireless LAN (WLAN) communication range. In this paper we address the benefits of hybrid wireless networks, showing their possible applications and presenting a classification for their emerging architectures. Also, we identify the research challenge arising from the problem of applying the grid computing concept in such hybrid wireless environment, showing the expected benefits from the aggregated fixed-mobile capacity. Finally, we propose our vision for a potential architectural model, which is expected to provide useful services by the network operator or the service provider in such a hybrid environment\",\n \"Title: A Bayesian Filter to Detect Misbehaving Nodes in MANETs\\nYear: 2008\\n\\nAbstract: Composed of mobile nodes, MANETs rely on the entire collaboration of nodes to provide routing and forwarding functions. Most MANET security solutions identify and exclude malicious and selfish nodes. These mechanisms rely on local monitoring tools to detect untrustworthy nodes and then spread trust information through recommendations. In this paper we apply a Bayesian model [1] to improve MANET security. We classify nodes behavior relying on a decision based on a probabilistic Bayesian model. The novelty of our approach is that it classifies nodes based on distant observations. We describe statistical parameters like Accuracy, Error and the Total Cost Ratio that are used to evaluate the efficiency of the filter through a set of simulations of an attacked pure ad hoc network.\",\n \"Title: A cross layer attack against MANET cooperation enforcement tools\\nYear: 2008\\n\\nAbstract: Composed of mobile nodes, MANETs rely on the entire collaboration of nodes to provide routing and forwarding functions. Many solutions have been proposed to enforce the collaboration of nodes in MANETs. Most of them rely on monitoring mechanisms to detect selfish or malicious behaviors. These mechanisms have in common the implicit use of MAC layer information in their detection process. This paper presents a new attack scheme against MANET monitoring tools. Our attack scheme takes advantage of MAC layer absence of authentication to spoof the identity of honest nodes and ruin their reputations. Simulations have been carried out to evaluate the potential of the attack on current cooperation mechanisms. Results emphasize the high vulnerability of current monitoring mechanisms and underline the necessity for cooperation enforcement tools to rely only on authenticated information.\",\n \"Title: ECTC: Energy effiCient topology control algorithm for wireless sensor networks\\nYear: 2009\\n\\nAbstract: Sensor network which operates on battery are used to gather data in a variety of environments. The data collected by each node is communicated through the network to the sink, which uses all reported data to determine characteristics of the environment or detect an event. Prolonging sensor's operable lifetime is a main design challenge of these networks. A good energy saving technique in this direction is to schedule nodes sleep interval with the communication radio turned off. In this paper, we propose a distributed topology control algorithm, termed ECTC, which uses a clustering approach. It is built on the notion that when a region of a shared channel wireless sensor network has a sufficient density of nodes, significant energy saving is obtained by allowing redundant nodes to sleep. Using the two-hop neighborhood information, certain nodes sequentially select a subset of nodes to be active among all nodes in the neighborhood, to ensure connectivity. Moreover, to ensure fairness, the role of active nodes is rotated periodically to ensure energy-balanced operations. Results from stochastic geometry are used to derive solutions for the values of parameters of our algorithm that minimize the total energy spent in the network when all sensor nodes report data through the cluster heads to the sink.\",\n \"Title: Controlled data collection of Mini-Sinks for maximizing packet delivery ratio and throughput using multiple paths in Wireless Sensor Networks\\nYear: 2012\\n\\nAbstract: We propose a new approach based on the use of many data collectors, which we designate Mini-Sinks (MSs), instead of a single sink in order to improve Wireless Sensor Network (WSN) performances. One or more MSs are mobile and move according to an arbitrary mobility model inside the sensor field in order to maintain a fully-connected network topology, collecting data based on the controlled Energy Conserving Routing Protocol (ECRP) within their coverage areas and forwarding it towards the single main sink. ECRP, based on route diversity, is implemented in MSs and sensors in order to optimize the transmission cost of the forwarding scheme. A set of multiple paths between MSs and sensors is generated to distribute the global traffic over the entire network. Simulations were performed in order to validate the performance of our new approach. We compare the results obtained with those for a single static sink and mobile sink, and show that our approach can achieve better results in terms of packet delivery ratio, throughput, end-to-end delay and multiple paths overhead.\",\n \"Title: A performance analysis of VANETs routing protocols using different mobility models\\nYear: 2010\\n\\nAbstract: In order to evaluate a vehicular network performance it is important to develop and use mobility models that accurately capture the realistic mobility characteristics of moving vehicles. In this paper, we present performance evaluation of various routing protocols including SIFT, GPSR and GOSR using different mobility models such as Random Waypoint Model (RWM), Fluid Traffic Model (FTM) and Intelligent Driver Model with Intersection Management (IDM-IM). We present simulation results that illustrate the importance of choosing a mobility model in the simulation of a vehicular network protocol. We illustrate how the performance results considerably change as a result of changing the simulated mobility model. We show how unreliable results can be obtained by using some models such as RWM and FTM. In addition, we demonstrate how more realistic mobility models such as IDM-IM often lead to more accurate results.\",\n \"Title: Safety message dissemination in VANETs: Flooding or trajectory-based?\\nYear: 2010\\n\\nAbstract: In this paper, we address the reliable alarm message dissemination in Vehicular Ad hoc NETworks (VANETs) environment. We study various techniques to disseminate emergency data, after a car crash, within a group of vehicles. We consider a trajectory-based data dissemination technique to perform broadcast flooding task optimization, and compare it with a pure flooding scheme. For the evaluation, we examine various parameters such as inter-vehicle distance, transmission radio range and traffic load. Experimental results, obtained by several simulations implemented on VanetMobiSim/NS-2 platform, show the effectiveness of trajectory-based solutions for efficient dissemination of emergency messages in VANETs. We also conclude that a simple flooding technique is not always considered harmful, and can outperform more complicated schemes in high density VANETs environment.\",\n \"Title: VANET Based Adaptive Traffic Signal Control\\nYear: 2011\\n\\nAbstract: In urban scenarios traffic signal controls are the main mechanism to control vehicular flow at the intersections. However, traditional systems fail to adjust the timing pattern in accordance to the time variability. An alternative to such systems is to develop dynamic systems which will alter the timing patterns according to the traffic demand. In this paper, an adaptive traffic signal control system based on car-to-car communication is designed and developed. This system reduces the waiting time of the vehicles at the intersection along with the reduction in queue length. It's also verified that the proposed solution is collision free at the intersections. The proposed system is compared with a classical pre-timed system. The simulations also show that the data convergence time and the communication delay between vehicle and traffic signal do not compromise the efficiency of the system.\",\n \"Title: A stable clustering algorithm for efficiency applications in VANETs\\nYear: 2011\\n\\nAbstract: Efficiency applications in VANETs are focused on increasing the productivity of the road resources by managing the traffic flow and monitoring the road conditions. The performance of most such applications is dependent on an effective density estimation of the vehicles in the surroundings. Of the various methods, clustering demonstrates to be an effective concept to implement this. However due to high mobility a stable cluster, within a vehicular framework, is difficult to implement. In this work, we propose a direction based clustering algorithm with a clusterhead switching mechanism. This mechanism is aimed to overcome the influence of overtaking within the clusters. The proposed algorithm facilitates to attain better stability and thus accurate density estimation within the clusters. Simulation results show that the proposed clustering algorithm is rendered stability through switching mechanism and hence provides a better accuracy in density estimation.\",\n \"Title: A multi-metric QoS-balancing scheme for gateway selection in a clustered hybrid VANET network\\nYear: 2012\\n\\nAbstract: In this paper, we propose a cooperative traffic transmission algorithm in a joint cellular and mobile ad hoc hybrid network architecture. The mobile ad hoc network is based on IEEE 802.11p standard. The focus of this paper is on defining an algorithm aiming to select the appropriate gateway for a given source vehicle under the scope of V2I communications. In this work, we consider the LTE Advanced infrastructure. We propose a multi-criteria and attribute scheme used to make a decision over the appropriate gateway to connect a source vehicle to the LTE Advanced infrastructure. It is a QoS-balancing gateway selection algorithm where the decision over the gateway depends on the traffic to be transmitted to the infrastructure. Other criteria are also considered such as loads, Received Signal Strengths (RSS) and Link Connectivity Durations of the cluster head and other gateway candidates. Simulation results demonstrate that our algorithm makes efficient decisions for electing the appropriate gateway that fits best the cluster and infrastructure features. An improvement of the RSS and the Link Connectivity Durations, while comparing to the commonly used gateway selection scheme, is noted.\",\n \"Title: Direction based clustering algorithm for data dissemination in vehicular networks\\nYear: 2009\\n\\nAbstract: Vehicular ad hoc networks (VANETs) are important component for the development of Intelligent Transportation System. Due to the features of VANET, data dissemination is an important issue that has to be addressed. In this paper we propose a direction based clustering algorithm for data dissemination. This protocol is used to estimate the density of vehicles on a given road. As in any clustering algorithm, the formation of the cluster and the use of the bandwidth are important tasks. In the proposed solution the packet is forwarded to vehicles only if they are moving along the same direction. The simulations show that the proposed protocol reduces the number of broadcast packets being sent on the network. To choose the best technology for VANET applications, the technologies 802.11p and 802.11b are compared with TCP/IP and Wireless Access Vehicular Environment (WAVE) stack protocols. This results obtained shows that WAVE stack is better than TCP/IP stack, in terms of performance, in vehicular environment.\",\n \"Title: Physical rate and contention window based admission control (PRCW) for 802.11 WLANs\\nYear: 2010\\n\\nAbstract: Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents a class based admission control algorithm for 802.11e based wireless local area networks. The strengths of our admission control is dynamicity and flexibility of the algorithm, which adapts to the situation of the BSS, like global load, number of best effort AC, and position of QSTA by report of QAP, thing that have never been taken together, but each solutions have used a point of sight separately. Thus it achieves higher throughput than other admission control for 802.11 e. The idea which consists of changing parameters [AIFSN, CWmin and CWmax] of best effort flows, for decreasing collisions, is used, so we think that it is an efficient way to protect QoS flows from best effort flows, and to allow reducing then number of collisions. So we increase AIFSN [best effort flow], CWmin and CWmax only at 70% of load of network, to prevent starvations of best effort flows, and so we increase rate utilization of channel. We also use the current rate transmission of QSTAs, according to their positions, instead of the minimum rate transmission used by standard 802.11e, for calculate the load of network and derived the TXOPi necessary for all the stations, with i=1 to number of active stations. The 802.11e standard starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities. A discussion is presented in detail using simulation-based evaluations, with an aim of comparing results of our admission control algorithm, with the 802.11e standard and the F- - HCF algorithm. Results reveal an improvement of the network load and a decrease of the number of collisions.\",\n \"Title: Cellular Content Download through a Vehicular Network: I2V Link Estimation\\nYear: 2015\\n\\nAbstract: Cellular networks are facing serious traffic overload problems due to the high users traffic demands, emphasized by the important penetration of smart phones and their greedy applications. The originality of this paper is to investigate upon the use of Intelligent Transportation Systems (ITS) for offloading the cellular infrastructure. We provide an analytical study based on an optimization problem formulation where the aim is to select a maximum target set of flows to route through the Vehicular Ad hoc Network (VANET). Offloading decision considers the VANET link availability, channel load (using contention), vehicle to vehicle link quality and the maximum volume that could be offloaded from the road side unit to the vehicular nodes. Simulation results show that the data offloading fraction is closely tied to the data volume of the flows, to the channel load and to the path quality. Results show also that 100% of best effort data traffics could be offloaded in some specific scenarios.\",\n \"Title: Security of C-ITS messages: A practical solution the ISE project demonstrator\\nYear: 2015\\n\\nAbstract: Cooperative Intelligent Transport Systems (C-ITS) offer innovative ways of wireless communication between Intelligent Transport Systems (ITS) stations and ITS road-side stations. They favour the development of ITS applications to improve traffic management, road safety, mobility and other comfort services. C-ITS systems have to guarantee communication security, especially in heterogeneous network environments. Safety critical applications require authentication to avoid attackers to send spoofed or reforged information, nevertheless, cars and drivers privacy must be maintained. We present a demonstration of the C-ITS security management infrastructure of the ITS-Security (ISE) project [1]. Through our demonstrator we show how ISE provides message authentication without violating cars and drivers privacy. Our demonstrator allows the public to run an attack scenario with and without the ISE security system, making evident importance of securing ITS communications.\",\n \"Title: RACE: Risk analysis for cooperative engines\\nYear: 2015\\n\\nAbstract: Nowadays, Cooperative Intelligent Transport Systems (C-ITS) are not fiction anymore. Prototypes of self-driving vehicles are flourishing everywhere, e.g. Google driverless car. These new generation vehicles are not only intelligent as they do not need human intervention during cruise, but they also communicate together creating a cooperative network. However, C-ITS are becoming the prey of hackers and the target of cyberattacks. Consequently, a reliable risk analysis method needs to be defined to prevent C-ITS threats and to assess their vulnerabilities. In this paper, we define a simple and efficient risk analysis method called RACE. We compare it to two of main risk analysis methods, namely TVRA and EVITA.\",\n \"Title: A new mobility-based clustering algorithm for vehicular ad hoc networks (VANETs).\\nYear: 2016\\n\\nAbstract: Clustering in vehicular ad hoc networks (VANETs) is a challenging issue due to the highly dynamic vehicle mobility and frequent communication disconnections problems. Recent years' research have proven that mobility-based clustering mechanisms considering speed, moving direction, position, destination and density, were more effective in improving cluster stability. In this paper, we propose a new mobility-based and stability-based clustering algorithm (MSCA) for urban city scenario, which makes use of vehicle's moving direction, relative position and link lifetime estimation. We evaluate the performance of our proposed algorithm in terms of changing maximum lane speed and traffic flow rate. Our proposed algorithm performs well in terms of average cluster head lifetime and average number of clusters.\",\n \"Title: A joint active time and flow selection model for cellular content retrieval through ITS.\\nYear: 2016\\n\\nAbstract: Operators need to address increased data demands to meet subscribers' growing requirements by offloading a portion of cellular traffic onto other types of networks. In this paper, we investigate the possibility of using vehicular ad hoc networks (VANETs) for this purpose. We study joint data flow selection and contention resolution in a hybrid VANET-cellular system. We formulate the problem as an optimization problem called FOSAA, which considers vehicle-to-vehicle and vehicle-to-infrastructure link quality, channel access, inter-nodal interference and node active time. The problem is solved through an iterative approach. FOSAA is compared to other proposed schemes. The performance results show that offloading fraction is significantly affected by the data volume, vehicle density and number of hops from the infrastructure to the downloader vehicles.\",\n \"Title: A Secure and Authenticated Key Management Protocol (SA-KMP) for Vehicular Networks.\\nYear: 2017\\n\\nAbstract: Public key infrastructure (PKI) is the most widely used security mechanism for securing communications over the network. However, there are known performance issues, making it unsuitable for use in vehicular networks. In this paper, we propose a secure and authenticated key management protocol (SA-KMP) to overcome the shortcomings of the PKI. The SA-KMP scheme distributes repository containing the...\",\n \"Title: A New Service Advertisement Message for ETSI ITS Environments: CAM-Infrastructure\\nYear: 2016\\n\\nAbstract: Collaborative Intelligent Transportation Systems are almost part of our everyday life. A C-ITS environment can provide numerous services that soon will become essential to roads' users. The latter resides in improvement of road safety, entertainment, and commercial services. However to provide such services, the C-ITS environment needs an advertisement and dissemination service of the latter. Indeed, users have to be aware of the available services in order to request them if needed. Actual standards of service announcement show their limits, especially regarding the support of several communication profiles. For this reason, this paper, describes a new service advertisement message called CAM-Infrastructure. The latter is compliant with ETSI standards and is deployed in a nationwide scale project.\",\n \"Title: Energy Efficient Multi-Layer Femtocell Networks\\nYear: 2016\\n\\nAbstract: In this paper, we present an energy efficient routing algorithm for multi-layer femtocell networks. We consider a four-layered architecture that consists users, femtocells, relays, and macro base stations. The traffic to/from users passes through this architecture and is aggregated from/to the Internet through gateways in the relay layer. The traffic demand from users changes from time to time, so that some relays can be put into sleep mode in non-peak time to save energy. We propose a simple and effective routing algorithm to decide routes and active relays, to satisfy user traffic demand and save energy. Simulation results show that our proposed method outperforms benchmark schemes.\",\n \"Title: Performance Evaluation of Link Metrics in Vehicle Networks: A Study from the Cologne Case.\\nYear: 2016\\n\\nAbstract: In vehicle ad hoc networks, the link duration is an important concept for clustering and dissemination. Many link metrics are proposed to predict it based on the vehicles' velocities and distance between vehicles. However, there is a lack of comparison of these metrics under the same framework. In this paper, we compare several common adopted link metrics, LLT (link life time), SLS (spatial locality similarity), and SF (similarity function), in the performance of link duration prediction, according to a real vehicular mobility trace of the city of Cologne, Germany. We find that there exists a large gap in between the predicted link duration order and real link duration order for the real traffic trace, and there is no winning link metric in all scenarios. Furthermore, as an example, we show that, by combining existing link metrics intelligently, it is possible to create a new link metric that predicts link duration better.\",\n \"Title: A non-biased trust model for wireless mesh networks.\\nYear: 2017\\n\\nAbstract: Trust models that rely on recommendation trusts are vulnerable to badmouthing and ballot-stuffing attacks. To cope with these attacks, existing trust models use different trust aggregation techniques to process the recommendation trusts and combine them with the direct trust values to form a combined trust value. However, these trust models are biased as recommendation trusts that deviate too much from oneu0027s own opinion are discarded. In this paper, we propose a non-biased trust model that considers every recommendation trusts available regardless they are good or bad. Our trust model is based on a combination of 2 techniques: the dissimilarity test and the Dempster-Shafer Theory. The dissimilarity test determines the amount of conflict between 2 trust records, whereas the Dempster-Shafer Theory assigns belief functions based on the results of the dissimilarity test. Numerical results show that our trust model is robust against reputation-based attacks when compared to trust aggregation techniques such as the linear opinion pooling, subjective logic model, entropy-based probability model, and regression analysis. In addition, our model has been extensively tested using network simulator NS-3 in an Infrastructure-based wireless mesh networks and a Hybrid-based wireless mesh networks to demonstrate that it can mitigate blackhole and grayhole attacks.\",\n \"Title: ASN.1 Specification for ETSI Certificates and Encoding Performance Study\\nYear: 2017\\n\\nAbstract: Cooperative Intelligent Transportation Systems (C-ITS) are gaining ground and are almost part of our everyday life. Within these environments, huge amounts of messages are exchanged. Besides, these messages should be secure in order to ensure users' privacy. Public Key Infrastructures (PKI) represent the most common security solution. Due to the vehicles speed, the communication with the PKI should be fully optimized. The European Telecommunications Standards Institute (ETSI) proposes a PKI architecture for C-ITS environments. However, unlike most of security standards as IEEE 1609.2, there is no Abstract Syntax Notation One (ASN.1) specification for the used certificates. For this reason, in this paper, we propose an ASN.1 definition for the ETSI certificate to help developers in its implementation. In addition, we provide an extensive comparative study of the different encoding schemes, applied to this proposal.\",\n \"Title: Tls For Cooperative Its Services\\nYear: 2017\\n\\nAbstract: TLS is currently receiving much attention and seems to be the most promising candidate as a secure protocol for the current and future online services. Many security protocols have been developed to handle security problems in various circumstances. However, these protocols are often limited and related to precised contexts and architectures and cannot answer special application and networks needs such as securing transactions between several vehicles in vehicular networks. In this paper, we propose to extend the Transport Layer Security (TLS) protocol by using ETSI and IEEE certificates to securely exchange data between multiple vehicular network components through a single TLS session. We propose a formal validation of our extension with the HLPSL language using AVISPA. The proposed extension is currently being implemented over OPENSSL.\",\n \"Title: A mobility-based scheme for dynamic clustering in vehicular ad-hoc networks (VANETs).\\nYear: 2017\\n\\nAbstract: Vehicle clustering is an efficient approach to improve the scalability of networking protocols in vehicular ad-hoc networks (VANETs). However, some characteristics, like highly dynamic topology and intermittent connections, may affect the performance of the clustering. Establishing and maintaining stable clusters is becoming one of big challenging issues in VANETs. Recent years' researches prove that mobility metric based clustering schemes show better performance in improving cluster stability. Mobility metrics, including moving direction, vehicle density, relative velocity and relative distance, etc., are more suitable for VANETs instead of the received radio strength (RSS) and identifier number metrics, which are applied for MANETs clustering. In this paper, a new dynamic mobility-based and stability-based clustering scheme is introduced for urban city scenario. The proposed scheme applies vehicle's moving direction, relative position and link lifetime estimation. We compared the performance of our scheme with Lowest-ID and the most recent and the most cited clustering algorithm VMaSC in terms of cluster head duration, cluster member duration, number of clusters, cluster head change rate and number of state changes. The extensive simulation results showed that our proposed scheme shows a better stability performance.\",\n \"Title: Link Duration Prediction in VANETs via AdaBoost.\\nYear: 2017\\n\\nAbstract: In this paper, we present a link duration prediction method in VANETs. It utilizes AdaBoost algorithm to combine several link metrics, such as distance, difference in velocities, link lifetime, and etc., to form a predictor with a higher accuracy. The proposed method is applicable to different traffic scenarios and does not rely on any assumption of vehicles' velocity distribution. We evaluate the performance of this Adaboost-based link duration prediction algorithm by various traffic traces generated by SUMO that represents different typical scenarios. The evaluation result shows that, the proposed method effectively improve link prediction accuracy. Compared with other machine learning based solutions such as linear regression and support vector regression, the proposed method also shows less prediction error consistently.\",\n \"Title: TEDS: A Trusted Entropy and Dempster Shafer Mechanism for Routing in Wireless Mesh Networks.\\nYear: 2017\\n\\nAbstract: Wireless Mesh Networks (WMNs) have emerged as a key technology for the next generation of wireless networking due to its self-forming, self-organizing and self-healing properties. However, due to the multi-hop nature of communications in WMN, we cannot assume that all nodes in the network are cooperative. Nodes may drop all of the data packets they received to mount a Denial of Service (DoS) attack. In this paper, we proposed a lightweight trust detection mechanism called Trusted Entropy and Dempster Shafer (TEDS) to mitigate the effects of blackhole attacks. This novel idea combines entropy function and Dempster Shafer belief theory to derive a trust rating for a node. If the trust rating of a node is less than a threshold, it will be blacklisted and isolated from the network. In this way, the network can be assured of a secure end to end path free of malicious nodes for data forwarding. Our proposed idea has been extensively tested in simulation using network simulator NS-3 and simulation results show that we are able to improve the packet delivery ratio with slight increase in normalized routing overhead.\",\n \"Title: SARA: Security Automotive Risk Analysis Method.\\nYear: 2018\\n\\nAbstract: Connected and automated vehicles aim to improve the comfort and the safety of the driver and passengers. To this end, car manufacturers continually improve actual standardized methods to ensure their customers safety, privacy, and vehicles security. However, these methods do not support fully autonomous vehicles, linkability and confusion threats. To address such gaps, we propose a systematic threat analysis and risk assessment framework, SARA, which comprises an improved threat model, a new attack method/asset map, the involvement of the attacker in the attack tree, and a new driving system observation metric. Finally, we demonstrate its feasibility in assessing risk with two use cases: Vehicle Tracking and Comfortable Emergency Brake Failure.\",\n \"Title: A Unified Framework of Clustering Approach in Vehicular Ad Hoc Networks.\\nYear: 2018\\n\\nAbstract: Effective clustering algorithms are indispensable in order to solve the scalability problem in vehicular ad hoc networks. Although current existing clustering algorithms show increased cluster stability under some certain traffic scenarios, it is still hard to address which clustering metric performs the best. In this paper, we propose a unified framework of clustering approach (UFC), composed of ...\",\n \"Title: Slicing-Based Offloading in Vehicular Edge Computing\\nYear: 2021\\n\\nAbstract: Vehicular edge computing (VEC) provides an environment for offloading tasks from vehicles. Indeed, the advantage through VEC is to push power computational and storage capacities at the edge nodes near the vehicles to handle the enormous resources required by some applications. On the other hand, in order to manage efficiently these resources, it would be necessary to partition them into several p...\",\n \"Title: An Analytical Model of Bluetooth Performance Considering Physical and MAC Layers’ Effects\\nYear: 2021\\n\\nAbstract: This paper presents an analytical model for the average Packet Error Rate (PER) of Bluetooth in Basic Rate (BR) mode. The effects of the physical layer and the MAC layer are taken into account. A Nakagami-m block fading is considered to take into account the effects of wireless channel fading. A Gaussian Frequency Shift Keying (GFSK) modulation scheme is used. Also, Forward Error Control (FEC) cod...\",\n \"Title: Dynamic Graph Convolutional LSTM application for traffic flow estimation from error-prone measurements: results and transferability analysis\\nYear: 2021\\n\\nAbstract: The technological advances in the transportation and automotive industry led to the use of new types of sensing systems more cost-effective and adapted to large-scale dense deployment. Those sensing techniques allow continuously gathering traffic measurements times series in different geospatial locations. The accuracy of the obtained raw measurements is often hindered by different factors related...\",\n \"Title: Dynamic Graph Convolutional LSTM application for traffic flow estimation from error-prone measurements: results and transferability analysis\\nYear: 2021\\n\\nAbstract: The technological advances in the transportation and automotive industry led to the use of new types of sensing systems more cost-effective and adapted to large-scale dense deployment. Those sensing techniques allow continuously gathering traffic measurements times series in different geospatial locations. The accuracy of the obtained raw measurements is often hindered by different factors related to the sensing environment and the sensing process itself and thus fail to capture the short-term traffic variations crucial for real-time traffic monitoring. In this paper, we propose the DGC-LSTM model for area-wide traffic estimation from error-prone measurements time series. The backbone of the DGC-LSTM model is a graph convolutional Long Short Term Memory model with a dynamic adjacency matrix. The adjacency matrix is learned and optimized during the model training. The adjacency matrix values are estimated from the set of contextual features that impact the dynamicity of the dependencies in both the spatial and temporal dimensions. Experiments on a realistic synthetic labelled Bluetooth counts dataset is used for model evaluation. Lastly, we highlight the importance of transfer learning methods to improve the model applicability by ensuring model adaptation to the new deployment site while avoiding the extensive data-labelling effort.\",\n \"Title: Joint Content-Prefetching, Transmission Scheduling, and Rate Adaptation in Vehicular Networks\\nYear: 2022\\n\\nAbstract: Content prefetching at road side units (RSUs) in vehicular networks can improve users’ experience by reducing the average data access latency. Prefetching algorithms proposed in the literature usually rely on a fixed modulation scheme, that corresponds to the lowest possible data rate for RSU-to-vehicles transmission. As a consequence, the network bandwidth is often inefficiently used. In this art...\",\n \"Title: Network slicing with load-balancing for task offloading in vehicular edge computing\\nYear: 2022\\n\\nAbstract: The support of edge computing for vehicular technologies gained increasing momentum with 5G to fulfill efficient offloading tasks from vehicles towards the edge nodes. Accordingly, vehicles demanding powerful computation and large storage resources will be directed to communicate with the nearest edge computing nodes hosted at a wireless 5G new generation nodes (gNBs) or a road side units (RSUs). To efficiently utilize the edge nodes' resources, network slicing and load-balancing features can greatly help in that, therefore, this paper proposes an algorithm for Vehicular Edge Computing (VEC) with network slicing and load-balancing based on resources utilization, denoted as VECSlic-LB, specifically dedicated for offloading tasks from vehicles to edge nodes at gNBs or RSUs. The algorithm can holistically view and manage the whole network, and use network function virtualization framework to manage the data plane. VECSlic-LB can handle a mix of slicing configurations, capable of balancing the loads between various slices per node, and can support multiple edge computing nodes. Several simulations were conducted comparing the performance of the proposed algorithm to the optimal solution, resulting on very close acceptance ratios as the optimal solution, and also was evaluated against a recent reference algorithm, providing more efficient resource utilizations ratios, saving up to 48% of the resources better than the state-of-art algorithm. (c) 2021 Elsevier Inc. All rights reserved.\",\n \"Title: Blockchain-Based Collaborative Certificate Revocation Systems Using Clustering\\nYear: 2022\\n\\nAbstract: Despite the decisive contribution of intelligent transport systems in road safety, they also open new vulnerabilities to cyber-attacks, particularly vehicle position-linked attacks. For that reason, centralized systems are becoming increasingly vulnerable to the growth of the connected-vehicle fleets as it becomes more challenging to revoke certificates in real-time. We have proposed a new method that integrates a decentralized, collaborative system to meet these challenges. This method efficiently allows Blockchain integration for vehicular network's cyber security by dynamically creating communities to revoke malicious vehicles in real-time. This article presents analytical models of the system of real-time revoking certificates and examines our solution's impact on two important types of attacks in V2X communications, Sybil and the faking position attacks. Our experiments using real V2X hardware demonstrated the feasibility and benefits of real-time revocation via vehicle communities. The results were obtained from consensus implementation in a vehicular network comprising three communicating vehicles and a single roadside unit. In parallel, simulations showed feasibility in large-scale communications. As a result, the exposure and detection times of our solution meet real-time requirements.\",\n \"Title: Toward Multiple-Phase MDP Model for Charging Station Recommendation\\nYear: 2022\\n\\nAbstract: There is an increasing need for charging station recommendation to minimize the overall charging time for electric vehicles and balance load for the charging stations. To grant this need, we model the recommendation problem as a Markov Decision Process (MDP) problem. However, the traditional MDP model has the issue of ‘curse of dimensionality’. To address this issue, we propose an extension of MDP: multiple-phase MDP, in which the state transition of MDP is decomposing into several phases, so as to reduce the state space and state transition complexities. This is done by introducing two states other than the normal state defined in MDP: post decision state and intermediate decision state. Then, we propose an online learning based algorithm to solve the formulated multiple-phase MDP model. Thanks to the reduced complexities of the state space and state transition, the proposed online algorithm can converge fast. By comparing to other recommendation mechanisms, such as game theory based recommendation and Q-learning based recommendation, our simulation evaluation demonstrates that our proposition can bring good performance.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":88,"string":"88"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":252,"string":"252"}}},{"rowIdx":253,"cells":{"question_id":{"kind":"string","value":"Marinella Petrocchi"},"question":{"kind":"string","value":"Generate an abstract for the title \"Formal Modelling And Verification In Service-Oriented Computing\" using the following items: Formal methods, computer network protocols, correctness properties, automatic tools, analysis."},"answer":{"kind":"string","value":"Formal methods and tools are a popular means of analysing the correctness properties of computer network protocols, such as safety, liveness and security. First the protocol under scrutiny is described in a formal language, which often results in a more precise definition of its function. Subsequently, the properties to be analysed are specified in a suitable logic. Finally, to decide whether or not the protocol fulfils certain properties, automatic tools are used to analyse it. The outcome either proves the protocol to be correct with respect to the relevant properties or shows there to be a problem."},"correct_answer":{"kind":"string","value":"Formal methods and tools are a popular means of analysing the correctness properties of computer network protocols, such as safety, liveness and security. First the protocol under scrutiny is described in a formal language, which often results in a more precise definition of its function. Subsequently, the properties to be analysed are specified in a suitable logic. Finally, to decide whether or not the protocol fulfils certain properties, automatic tools are used to analyse it. The outcome either proves the protocol to be correct with respect to the relevant properties or shows there to be a problem."},"documents":{"kind":"list like","value":["Title: Evaluating the Trust of Android Applications through an Adaptive and Distributed Multi-criteria Approach\nYear: 2013\n\nAbstract: New generation mobile devices, and their app stores, lack of a methodology to associate a level of trust to applications to faithfully represent their potential security risks. This problem is even more critical with newly published applications, for which either user reviews are missing or the number of downloads is still low. In this scenario, users may not fully estimate the risk associated with downloading apps found on on-line stores. Hence, here we propose a methodology for evaluating the trust level of an application through an adaptive, flexible, and dynamic framework. The evaluation of an application trust is performed using both static and dynamic parameters, which consider the application meta-data, its run-time behavior and the reports of users with respect to the software critical operations. We have validated the proposed approach by testing it on more than 180 real applications found both on official and unofficial markets by showing that it correctly categorizes applications as trusted or untrusted in 94% of the cases and it is resilient to poisoning attacks.","Title: Authenticity in a reliable protocol for mobile computing\nYear: 2003\n\nAbstract: We consider a known protocol for reliable multicast in distributed mobile systems where mobile hosts communicate with a wired infrastructure by means of wireless technology. The original specification of the protocol does not take into consideration any notion of computer security: an adversary may eavesdrop on communications between hosts and inject packets over the wireless links. We suggest a secured version of the protocol providing authenticity and integrity of packets over the wireless links. The secure mechanisms introduced rely on two different techniques: secure wireless channels and 1-time signature schemes. Further, we outline the formal verification of part of the secured protocol.","Title: A prototype for solving conflicts in XACML-based e-Health policies.\nYear: 2013\n\nAbstract: The Electronic Patient Record (EPR) enables the sharing of medical documents among several and widespread healthcare organizations. To guarantee privacy properties, access control policies should be defined, regulating how the documents can be shared. Conflicts may occur among policies applicable to the same access request. We present a running prototype, based on an XACML engine, that implements a conflict resolution strategy as an extension to the standard combining algorithms of the XACML engine. We evaluate the efficiency of our proposal in terms of execution time, on a variable number of conflicting rules.","Title: Subjective review-based reputation\nYear: 2012\n\nAbstract: The choice of a product or a service is often influenced by its reputation, which is usually calculated from existing reviews of this product or service. A review can be either objective, for instance when referring to concrete features of a product, or subjective, for instance when referring to the feeling of the reviewer about one aspect. Subjective reviews are potentially biased by the characteristics of the reviewers, and therefore two subjective reviews should not be treated equally. We propose in this paper a model of reputation compensating the subjective bias of di?erent categories of reviewers. We firstly calculate this bias by analyzing the ratio between reviews coming from different categories, and then we project a subjective reputation for a given category of reviewer. We demonstrate the accuracy of our bias calculation with an experimentation on public reviews for hotels, and two specific categories of users.","Title: Formal Anaylsis of Some Timed Security Properties in Wireless Protocols\nYear: 2003\n\nAbstract: We show how a recent language for the description of cryptographic protocols in a real time setting may be suitable to formally verify security aspects of wireless protocols. We define also a compositional proof rule for establishing security properties;of such protocols. The effectiveness of our approach is shown by defining and studying the timed integrity property for muTESLA, a well-known protocol for wireless sensor networks. We are able to deal with protocol specifications with an arbitrary number of agents (senders as well as receivers) running the protocol.","Title: Formal Models and Analysis of Secure Multicast in Wired and Wireless Networks\nYear: 2008\n\nAbstract: The spreading of multicast technology enables the development of group communication and so dealing with digital streams becomes more and more common over the Internet. Given the flourishing of security threats, the distribution of streamed data must be equipped with sufficient security guarantees. To this aim, some architectures have been proposed, to supply the distribution of the stream with guarantees of, e.g., authenticity, integrity, and confidentiality of the digital contents. This paper shows a formal capability of capturing some features of secure multicast protocols. In particular, both the modeling and the analysis of some case studies are shown, starting from basic schemes for signing digital streams, passing through protocols dealing with packet loss and time-synchronization requirements, concluding with a secure distribution of a secret key. A process-algebraic framework will be exploited, equipped with schemata for analysing security properties and compositional principles for evaluating if a property is satisfied over a system with more than two components.","Title: On Relating and Integrating Two Trust Management Frameworks\nYear: 2007\n\nAbstract: In this paper, we continue our line of research for defining an integrated framework for the specification and analysis of security and trust, aimed at providing the basis for the modeling and analysis of security and trust aspects of emergent dynamic coalitions (e.g., mobile ad hoc networks, peer to peer systems, web services). In particular, we consider two well-known languages: 1) the Role-based Trust-management framework (RT) and, in particular, its most basic language RT\"0, and 2) the transitive trust model, for defining trust and recommendation relationships. First, we show an encoding of the transitive trust model into part of RT\"0; then, this subset is mapped into the inference construct of the Crypto-CCS process algebra. Also, we introduce in the languages operators dealing with levels of trust. The relationships among these languages could allow us to model and analyze trust and recommendation issues in distributed systems by means of standard formal techniques, based on inference systems.","Title: Formal analysis of some secure procedures for certificate delivery\nYear: 2006\n\nAbstract: This paper describes and formally analyses two communication protocols that manage the secure emission of digital certificates. The formal analysis is carried out by means of a software tool for the automatic verification of cryptographic protocols with finite behaviour. The tool is able to discover, at a conceptual level, attacks against security procedures. The methodology is general enough to be applied to several kinds of cryptographic procedures and protocols. It is the opinion of the authors that this approach contributes towards a better understanding of the structure and aims of a protocol, for developers, analysers and final users. Copyright (C) 2005 John Wiley & Sons, Ltd.","Title: Towards an executable algebra for product lines\nYear: 2012\n\nAbstract: We propose the Controlled Language for Software Product Lines CL4SPL with the twofold aim of ensuring simplicity of use for product line engineers and safe translations to executable languages amenable for automated verification. We show an implementation of CL4SPL in Maude, a well-known rewrite engine, thus allowing formal analyses over product families specified with CL4SPL. We illustrate our approach with a toy family of coffee machines.","Title: A Uniform Framework for Security and Trust Modeling and Analysis with Crypto-CCS\nYear: 2007\n\nAbstract: In this paper, we present our line of research for defining an integrated framework for the specification and analysis of security and trust in complex and dynamic scenarios. We aim at showing how the same machinery applied for the formal verification of security protocols may be useful to model and analyze trust management procedures.","Title: Modelling a Secure Agent with Team Automata\nYear: 2006\n\nAbstract: We use Team Automata in order to model a protocol by Cachin et al. for securing agents in a hostile environment. Our study focuses on privacy properties of the agents. We use the framework to prove a result from the work by Cachin et al. As a by-product, our analysis gives some initial insight on the limits of the protocol. From a different perspective, this study continues a line of research on the expressive power and modelling capabilities of Team Automata. To the best of our knowledge, this is the first attempt to use Team Automata for the analysis of privacy properties.","Title: SEAS: A Secure E-Voting Applet System\nYear: 2003\n\nAbstract: This paper presents SEAS, the Secure E-voting Applet System, a protocol for implementing a secure and private system for polling over computer networks, usable in distributed organizations whose members may range up to dozens of thousands. We consider an architecture requiring the minimum number of servers involved in the validation and voting phases. Sensus, [7], a well known e-voting protocol, requires only two servers, namely a validator and a tallier. Even if satisfying most of the security requirements of an e-voting system, Sensus suffers of a vulnerability that allows one of the entities involved in the election process to cast its own votes in place of those that abstain from the vote. SEAS is a portable and flexible system that preserves the lightness of Sensus, but it avoids the mentioned weakness. We propose a prototype implementation of SEAS based on Java applet and XML technology.","Title: Automated Analysis of Some Security Mechanisms of SCEP\nYear: 2002\n\nAbstract: The paper analyzes SCEP, the Simple Certificate Enrollment Procedure, a two-way communication protocol to manage the secure emission of digital certificates to network devices. The protocol provides a consistent method of requesting and receiving certificates from different Certification Authorities by offering an open and scalable solution for deploying certificates which can be beneficial to all network devices and IPSEC software solutions.We formally analyze SCEP through a software tool for the automatic analysis of cryptographic protocols able to discover, at a conceptual level, attacks against security procedures. Our method of survey contributes towards a better understanding of the structure and aims of a protocol both for developers, analyzers and final users.","Title: Signed and Weighted Trust Credentials in Fraglets.\nYear: 2008\n\nAbstract: We continue our line of research by extending the Fraglets computation model with digital signature and security credentials dealing with a quantitative notion of trust. We also give a modeling example where trust credentials are managed at fraglets level.","Title: Compositional Verification of Secure Streamed Data: A Case Study with EMSS\nYear: 2003\n\nAbstract: We consider an instance of the EMSS protocol proposed in [19], authenticating streamed data in the presence of packet loss. We formally prove the integrity property of the instance by applying a compositional proof rule that allows us to check a specification with an arbitrary number of parallel processes. We argue that our approach may be applied to a wider class of stream signature protocols.","Title: Executable Specification of Cryptofraglets in Maude for Security Verification.\nYear: 2009\n\nAbstract: Fraglets are computation fragments flowing through a computer network. They implement a chemical reaction model where computations are carried out by having fraglets react with each other. The strong connection between their way of transforming and reacting and some formal rewriting system makes a fraglet program amenable to verification. Starting from a threat model which we intend to use for modeling secure communication protocols with fraglets, we propose an executable specification of fraglets (and fraglets-based cryptographic protocols) in the rewriting logic-based Maude interpreter.","Title: Mobile Implementation and Formal Verification of an e-Voting System\nYear: 2008\n\nAbstract: We propose a mobile implementation of an e-voting protocol. We also provide a formal analysis to validate a security property of our system.","Title: A team automaton scenario for the analysis of security properties of communication protocols\nYear: 2006\n\nAbstract: Formal methods are a popular means to specify and verify security properties of a variety of communication protocols. In this article we take a step towards the use of team automata for the analysis of security aspects in such protocols. To this aim, we define an insecure communication scenario for team automata that is general enough to encompass various communication protocols. We then reformulate the Generalized Non-Deducibility on Compositions schema -originally introduced in the context of process algebrae -in terms of team automata. Based on the resulting team automata framework, we subsequently develop two analysis strategies that can be used to verify security properties of communication protocols. Indeed, the paper concludes with two case studies in which we show how our framework can be used to prove integrity and secrecy in two different settings: We show how integrity is guaranteed in a team automaton model of a particular instance of the Efficient Multi-chained Stream Signature protocol, a communication protocol for signing digital streams that provides some robustness against packet loss, and we show how secrecy is preserved when a member of a multicast group leaves the group in a particular run of the complementary variable approach to the N-Root/Leaf pairwise keys protocol.","Title: Team Automata for Security: - A Survey -.\nYear: 2005\n\nAbstract: In [Kleijn, J., Team Automata for CSCW – A Survey –, Petri Net Technology for Communication-Based Systems—Advances in Petri Nets, LNCS 2472, Springer, 2003, 295–320], Kleijn presented a survey of the use of team automata for the specification and analysis of phenomena from the field of computer supported cooperative work, in particular notions related to groupware systems. In this paper we present a survey of the use of team automata for the specification and analysis of some issues from the field of security. In particular, we show how team automata can adequately be used to model and verify various access control policies, multicast/broadcast communication protocols, and general (cryptographic) communication protocols.","Title: Combining declarative and procedural views in the specification and analysis of product families\nYear: 2013\n\nAbstract: We introduce the feature-oriented language FLan as a proof of concept for specifying both declarative aspects of product families, namely constraints on their features, and procedural aspects, namely feature configuration and run-time behaviour. FLan is inspired by the concurrent constraint programming paradigm. A store of constraints allows one to specify in a declarative way all common constraints on features, including inter-feature constraints. A standard yet rich set of process-algebraic operators allows one to specify in a procedural way the configuration and behaviour of products. There is a close interaction between both views: (i) the execution of a process is constrained by its store to forbid undesired configurations; (ii) a process can query a store to resolve design and behavioural choices; (iii) a process can update the store by adding new features. An implementation in the Maude framework allows for a variety of formal automated analyses of product families specified in FLan, ranging from consistency checking to model checking.","Title: A design phase for data sharing agreements\nYear: 2011\n\nAbstract: The number of factories, service providers, retailers, and final users that create networks and establish collaborations for increasing their productivity and competitiveness is constantly growing, especially by effect of the globalization and outsourcing of industrial activities. This trend introduces new complexities in the value supply chain, not last the need for secure and private data sharing among the collaborating parties. A Data Sharing Agreement (DSA) represents a flexible means to assure privacy and security of electronic data exchange. DSA is a formal document regulating data exchange in a controlled manner, by defining a set of policies specifying what parties are allowed, or required, or denied to do with respect to data covered by the agreement. A key factor in the adoption of DSAs is their usability. Here, we propose an approach for a consistent and automated design phase of the agreements. In particular, we present an authoring tool for a user-friendly and cooperative editing of DSA and an analysis tool to identify possible conflicts or incompatibilities among the DSA policies.","Title: Automated Synthesis and Ranking of Secure BPMN Orchestrators\nYear: 2014\n\nAbstract: The authors describe a formal methodology for the automatic synthesis of a secure orchestrator for a set of BPMN processes. The synthesized orchestrator is able to guarantee that all the processes that are started reach their end, and the resulting orchestrator process is secure, that is, it does not allow the disclosure of certain secret messages. The authors present an implementation of a forth and back translation from BPMN to Crypto-CCS, that permits them to exploit the previously existing PaMoChSA tool to synthesize BPMN orchestrators. Furthermore, they study the problem of ranking orchestrators based on quantitative valuations of a process, the temporal evolution of such valuations, and their security, as a function of the knowledge of the attacker.","Title: Discriminating Between The Wheat And The Chaff In Online Recommendation Systems\nYear: 2014\n\nAbstract: MyChoice is an ambitious research project that aims to model, detect, and isolate outliers (aka fake) in online recommendation systems, as well as in online social networks. The final outcome of the project will be the prototype of an automated engine able to recognize fake information, such as reviews, and fake friends/followers, and able to filter out malicious material, in order to return reliable and genuine content to the user.","Title: Compositional Verification of Integrity for Digital Stream Signature Protocols\nYear: 2003\n\nAbstract: We investigate the application of concurrency theory notions as simulation relations and compositional proof rules for verifying digital stream signature protocols. In particular, we formally prove the integrity of the Gennaro-Rohatgi protocols in [7]. As a peculiarity, our technique is able to check a protocol with an unbounded number of parallel processes. We argue also that our approach may be applied to a wider class of stream signature protocols.","Title: CNL4DSA: a controlled natural language for data sharing agreements\nYear: 2010\n\nAbstract: A Data Sharing Agreement (DSA) is an agreement among contracting parties regulating how they share data. A DSA represents a flexible mean to assure privacy of data exchanged on the Web. As an example, a set of intelligent user agents may interact with each other, and by means of DSA, may negotiate privacy requirements on behalf of human users. However, a key factor for the adoption of privacy's technologies is not only their reliability, but also their usability. Here, we propose CNL4DSA, a Controlled Natural Language for DSA aiming at lowering the barrier to adoption of DSA, and, at the same time, ensuring mapping to formal languages that enable the automatic verification of agreements.","Title: Fast certificate-based authentication scheme in multi-operator maintained wireless mesh networks\nYear: 2010\n\nAbstract: In this paper, we consider QoS aware mesh networks that are maintained by multiple operators and they cooperate in the provision of networking services to the mesh clients. In order to support mobile users and seamless handover between the access points, the authentication delay has to be reduced. Many proposed fast authentication schemes rely on trust models that are not appropriate in a multi-operator environment. In this paper, we propose two certificate-based authentication schemes such that the authentication is performed locally between the access point and the mesh client. We assume that the access point is always a constrained device, and we propose different mechanisms for mesh clients with different computational performance. For constrained devices, we propose a mechanism where weak keys are used for digital signatures to decrease the latency of the authentication. The authenticity of the weak keys are provided by short-term certificates issued by the owner of the key. The short-term certificate has the digital signature generated by the owner's long-term key. We prove formally that the use of our weak key mechanism on the mesh client side is as secure as the use of some stronger keys. We perform a detailed performance evaluation on our proof-of-concept implementation, and we also compare our solution to the current standard methods.","Title: SEAS, a secure e-voting protocol: Design and implementation\nYear: 2005\n\nAbstract: This paper presents SEAS, the Secure E-voting Applet System, a protocol for implementing a secure system for polling over computer networks, usable in distributed organizations whose members may range up to dozens of thousands. We consider an architecture requiring the minimum number of servers involved in the validation and voting phases. Sensus, [Cranor L, Cytron RK. Sensor: a security-conscious electronic polling system for the internet. In: Proceedings of HICSS'97. IEEE; 1997. p. 561-70], a well-known e-voting protocol, requires only two servers, namely a validator and a tallier. Even if satisfying most of the security requirements of an e-voting system, Sensus suffers from a vulnerability that allows one of the entities involved in the election process to cast its own votes in place of those that abstain from the vote. SEAS is a portable and flexible system that preserves the limited number of servers of Sensus, but it avoids the mentioned vulnerability. We propose a prototype implementation of SEAS based on Java applet and XML technology.","Title: A Formalization of Credit and Responsibility Within the GNDC Schema\nYear: 2006\n\nAbstract: We formally define a notion of credit and responsibility within the Generalized Non Deducibility on Compositions framework. We investigate the validity of our definitions through some examples discussed in the literature.","Title: Towards Security Analyses of an Identity Federation Protocol for Web Services in Convergent Networks\nYear: 2007\n\nAbstract: We describe a formal approach to the analysis of security aspects of an identity federation protocol for web services in convergent networks. This network protocol was proposed by Telecom Italia as a solution to allow end users to access services on the web through different access networks without explicitly providing any credentials, while the service providers can trust the user's identity information provided by the access networks and access some user data. As a first step towards a full-blown formal security analysis of the protocol, we specify three user scenarios in the process algebra Crypto-CCS and verify the vulnerability of one of these specifications w.r.t. a man-in-the-middle attack with the model checker PaMoChSA.","Title: Security and Trust Management: 8th International Workshop, STM 2012, Pisa, Italy, September 13-14, 2012, Revised Selected Papers\nYear: 2013\n\nAbstract: This book constitutes the thoroughly refereed post-conference proceedings of the 8th International Workshop on Security and Trust Management, STM 2012, held in Pisa, Italy, in September 2012 - in conjunction with the 17th European Symposium Research in Computer Security (ESORICS 2012). The 20 revised full papers were carefully reviewed and selected from 57 submissions. The papers are organized into topical sections on policy enforcement and monitoring; access control; trust, reputation, and privacy; distributed systems and physical security; authentication and security policies.","Title: Cryptofraglets Reloaded - Bioinspired Security Modeling of a RFID Protocol and Properties.\nYear: 2014\n\nAbstract: Fraglets represent an execution model for communication protocols that resembles the chemical reactions in living organisms. The strong connection between their way of transforming and reacting and formal rewriting systems makes a fraglet program amenable to automatic verification. Starting from past work where the model has been enriched and executed to specify security protocols and properties (leading to the definition of cryptofraglets), this paper updates cryptofraglets and gives examples of concrete sample analyses over a secure RFID protocol.","Title: Engineering the Lifecycle of Data Sharing Agreements.\nYear: 2015\n\nAbstract: Sharing data among groups of organizations and/or individuals is essential in a modern web-based society, being at the very core of scientific and business transactions. Data sharing, however, poses several problems including trust, privacy, data misuse and/or abuse, and uncontrolled propagation of data. We describe an approach to preserve privacy whilst data sharing based on scientific Data Sharing Agreements (DSA).","Title: A Lot Of Slots - Outliers Confinement In Review-Based Systems\nYear: 2014\n\nAbstract: Review-based websites such as, e.g., Amazon, eBay, Trip-Advisor, and Booking have gained an extraordinary popularity, with millions of users daily consulting online reviews to choose the best services and products fitting their needs. Some of the most popular review-based websites rank products by sorting them aggregating the single ratings through their arithmetic mean. In contrast, recent studies have proved that the median is a more robust aggregator, in terms of ad hoc injections of outlier ratings. In this paper, we focus on four different types of ratings aggregators. We propose to the slotted mean and the slotted median, and we compare their mathematical properties with the mean and the median. The results of our experiments highlight advantages and drawbacks of relying on each of these quality indexes. Our experiments have been carried out on a large data set of hotel reviews collected from Booking. com, while our proposed solutions are rooted on sound statistical theory. The results shown in this paper, other than being interesting on their own, also call for further investigations.","Title: Access Control Mechanisms For Fraglets\nYear: 2007\n\nAbstract: The paper describes a revised version of Crypto-fraglets, and an enhancement of the framework with access control mechanisms. Fraglets is an interesting computing model that has connections with communication protocols, formal rewriting systems and biological systems. Indeed, fraglets basic mechanisms resemble bio-chemical reactions.","Title: Crypto-fraglets: Networking, Biology and Security\nYear: 2006\n\nAbstract: The paper describes connections between two models dealing with communication protocols, the fraglet model and the formal language of MultiSet Rewriting, which has very good inspiration from biology. By starting from similarities in their capabilities of modeling (indeed, their strong analogies in modeling biological systems), the programming language of the first model is translated into rule of the second model. Moreover, we propose an extended version of fraglets, namely Crypto-fraglets, as an initial step towards the intent of enlarging the set of communication protocols that this framework is currently able to describe, model and simulate.","Title: An Expertise-Driven Authoring Tool for E-Health Data Policies\nYear: 2014\n\nAbstract: Data sharing is crucial in many aspects of nowadays life, from economy to leisure, from public administration to healthcare. However, it implies several privacy issues that have to be managed. Definition of appropriate policies helps to safeguard the data privacy. This paper describes an expertise-driven authoring tool for privacy policies to be applied to the healthcare scenario. The tool exhibits two different interfaces, designed according to specific expertise of the policy authors. It is part of a general framework for editing, analysis, and enforcement of privacy policies. Furthermore, this serves as a first brick for a usability study on such tools.","Title: Fame for sale: Efficient detection of fake Twitter followers.\nYear: 2015\n\nAbstract: Fake followers are those Twitter accounts specifically created to inflate the number of followers of a target account. Fake followers are dangerous for the social platform and beyond, since they may alter concepts like popularity and influence in the Twittersphere—hence impacting on economy, politics, and society. In this paper, we contribute along different dimensions. First, we review some of the most relevant existing features and rules (proposed by Academia and Media) for anomalous Twitter accounts detection. Second, we create a baseline dataset of verified human and fake follower accounts. Such baseline dataset is publicly available to the scientific community. Then, we exploit the baseline dataset to train a set of machine-learning classifiers built over the reviewed rules and features. Our results show that most of the rules proposed by Media provide unsatisfactory performance in revealing fake followers, while features proposed in the past by Academia for spam detection provide good results. Building on the most promising features, we revise the classifiers both in terms of reduction of overfitting and cost for gathering the data needed to compute the features. The final result is a novel Class A classifier, general enough to thwart overfitting, lightweight thanks to the usage of the less costly features, and still able to correctly classify more than 95% of the accounts of the original training set. We ultimately perform an information fusion-based sensitivity analysis, to assess the global sensitivity of each of the features employed by the classifier.","Title: A Matter Of Words: Nlp For Quality Evaluation Of Wikipedia Medical Articles\nYear: 2016\n\nAbstract: Automatic quality evaluation of Web information is a task with many fields of applications and of great relevance, especially in critical domains, like the medical one. We move from the intuition that the quality of content of medical Web documents is affected by features related with the specific domain. First, the usage of a specific vocabulary (Domain Informativeness); then, the adoption of specific codes (like those used in the infoboxes of Wikipedia articles) and the type of document (e.g., historical and technical ones). In this paper, we propose to leverage specific domain features to improve the results of the evaluation of Wikipedia medical articles, relying on Natural Language Processing (NLP) and dictionaries-based techniques. The results of our experiments confirm that, by considering domain-oriented features, it is possible to improve existing solutions, mainly with those articles that other approaches have less correctly classified.","Title: DNA-inspired online behavioral modeling and its application to spambot detection.\nYear: 2016\n\nAbstract: A novel, simple, and effective approach to modeling online user behavior extracts and analyzes digital DNA sequences from user online actions and uses Twitter as a benchmark to test the proposal. Specifically, the model obtains an incisive and compact DNA-inspired characterization of user actions. Then, standard DNA analysis techniques discriminate between genuine and spambot accounts on Twitter. ...","Title: Domain-Specific Queries And Web Search Personalization: Some Investigations\nYear: 2015\n\nAbstract: Major search engines deploy personalized Web results to enhance users' experience, by showing them data supposed to be relevant to their interests. Even if this process may bring benefits to users while browsing, it also raises concerns on the selection of the search results. In particular, users may be unknowingly trapped by search engines in protective information bubbles, called \"filter bubbles\", which can have the undesired effect of separating users from information that does not fit their preferences. This paper moves from early results on quantification of personalization over Google search query results. Inspired by previous works, we have carried out some experiments consisting of search queries performed by a battery of Google accounts with differently prepared profiles. Matching query results, we quantify the level of personalization, according to topics of the queries and the profile of the accounts. This work reports initial results and it is a first step a for more extensive investigation to measure Web search personalization.","Title: A quality model for social networks populated with web services\nYear: 2015\n\nAbstract: This paper presents the development and evaluation of a $$\\mathcal {Q}$$Qo$$\\mathcal {SN}$$SN (standing for $$\\mathcal {Q}$$Quality of $$\\mathcal {S}$$Social $$\\mathcal {N}$$Network) model for social networks populated with Web services. These Web services are given the opportunity to select the networks in which they would like to sign in taking into account their concerns (in fact their providers' concerns) like better protection to their details and better exposure to potential users. To support Web services selection, the $$\\mathcal {Q}$$Qo$$\\mathcal {SN}$$SN model is built upon four criteria including robustness, trust, fairness, and traceability. The computation of these criteria uses a cryptographic technique known as secure multi-party computation. Different experiments showing how the networks react to Web services' actions (e.g., attack, join, and kick out) are also presented in the paper.","Title: Towards safer information sharing in the cloud.\nYear: 2015\n\nAbstract: Web interactions usually require the exchange of personal and confidential information for a variety of purposes, including enabling business transactions and the provisioning of services. A key issue affecting these interactions is the lack of trust and control on how data are going to be used and processed by the entities that receive it. In the traditional world, this problem is addressed using contractual agreements, those are signed by the involved parties, and law enforcement. This could be done electronically as well but, in addition to the trust issue, there is currently a major gap between the definition of legal contracts regulating the sharing of data, and the software infrastructure required to support and enforce them. How to enable organisations to provide more automation in this process? How to ensure that legal contracts can be actually enforced by the underlying IT infrastructure? How to enable end-users to express their preferences and constraints within these contracts? This article describes our R&D work to make progress towards addressing this gap via the usage of electronic Data Sharing Agreements (e-DSA). The aim is to share our vision, discuss the involved challenges and stimulate further research and development in this space. We specifically focus on a cloud scenario because it provides a rich set of use cases involving interactions and information sharing among multiple stakeholders, including users and service providers.","Title: Bioinspired Security Analysis of Wireless Protocols.\nYear: 2016\n\nAbstract: Fraglets represent an execution model for communication protocols that resembles the chemical reactions in living organisms. The strong connection between their way of transforming and reacting and formal rewriting systems makes a fraglet program amenable to automatic verification. Grounded on past work, this paper investigates feasibility of adopting fraglets as model for specifying security protocols and analysing their properties. In particular, we give concrete sample analyses over a secure RFID protocol, showing evolution of the protocol run as chemical dynamics and simulating an adversary trying to circumvent the intended steps. The results of our analysis confirm the effectiveness of the cryptofraglets framework for the model and analysis of security properties and eventually show its potential to identify and uncover protocol flaws.","Title: Legal and Technical Perspectives in Data Sharing Agreements Definition.\nYear: 2015\n\nAbstract: An electronic Data Sharing Agreement (DSA) is a human-readable, yet machine-processable contract, regulating how organizations and/or individuals share data. In this paper, we shed light on DSA engineering, i.e., the process of studying how data sharing is ruled in traditional legal human-readable contracts and mapping their fields (and rules) into formats that are machine-processable, leading to the transposition of the traditional contract into the electronic DSA. Tangible creation of the electronic DSA is possible through the design and implementation of a three-step DSA definition phase, with an associated authoring tool. The tool is specifically tailored for encoding not only the terms of law but also the rules that an organization may have put in place (e.g., corporate internal policies, or privacy policies, or data processing agreements) to manage the data, as well as end users’ privacy preferences.","Title: VISIO: A Visual Approach for Singularity Detection in Recommendation Systems\nYear: 2015\n\nAbstract: Reviews are a powerful decision-making tool for potential new customers, since they can significantly influence consumer purchase decisions, hence resulting in financial gains or losses for businesses. In striving for trustworthy review systems, validating reviews that could negatively or positively bias new customers is of utmost importance. To this goal, we propose VISIO: a visualization based representation of reviews that enables quick analysis and elicitation of interesting patterns and singularities. In fact, VISIO is meant to amplify cognition, supporting the process of singling out those reviews that require further analysis. VISIO is based on a theoretically sound approach, while its effectiveness and viability is demonstrated applying it to real data extracted from Tripadvisor and Booking.com.","Title: Using Incentives To Analyze Social Web Services' Behaviors\nYear: 2014\n\nAbstract: This paper discusses how incentives allow social networks to attract more members and reward those that are honest by retaining them. These members referred to as social Web services process users' requests in return for a certain usage fee and also expose certain behaviors in return of the incentives they receive. The usage fee is linked to a performance level that the social Web service needs to maintain at run time. In the case of any discrepancy between the usage fee and performance level the social Web service is expected to compensate users. However the compensation might not always take place. Simulation results illustrate why honesty is rewarding for social Web services, which has a positive impact on both their performance and the performance of the networks to which they belong.","Title: 1st international workshop on TEchnical and LEgal aspects of data pRIvacy and SEcurity (TELERISE 2015)\nYear: 2015\n\nAbstract: This paper is the report on the 1st International Workshop on TEchnical and LEgal aspects of data pRIvacy and SEcurity (TELERISE 2015) at the 37th International Conference on Software Engineering (ICSE 2015). TELERISE investigates privacy and security issues in data sharing from a technical and legal perspective. Keynote speech as well as selected papers presented at the event fit the topics of the workshop. This report gives the rationale of TELERISE and it provides a provisional program.","Title: Visual detection of singularities in review platforms\nYear: 2015\n\nAbstract: Product and service reviews can markedly influence consumer purchase decisions, leading to financial gains or losses for businesses. Therefore, there is a growing interest towards techniques for bringing out reviews that could negatively or positively bias new customers. To this goal, we propose a visual analysis of reviews that enables quick elicitation of interesting patterns and singularities. The proposed approach is based on a theoretically sound framework, while its effectiveness and viability is demonstrated by its application to real data extracted from Tripadvisor and Booking.com.","Title: TRAP: Using Targeted ads to unveil Google personal profiles\nYear: 2015\n\nAbstract: In the last decade, the advertisement market spread significantly in the web and mobile app system. Its effectiveness is also due thanks to the possibility to target the advertisement on the specific interests of the actual user, other than on the content of the website hosting the advertisement. In this scenario, became of great value services that collect and hence can provide information about the browsing user, like Facebook and Google. In this paper, we show how to maliciously exploit the Google Targeted Advertising system to infer personal information in Google user profiles. In particular, the attack we consider is external from Google and relies on combining data from Google AdWords with other data collected from a website of the Google Display Network. We validate the effectiveness of our proposed attack, also discussing possible application scenarios. The result of our research shows a significant practical privacy issue behind such type of targeted advertising service, and call for further investigation and the design of more privacy-aware solutions, possibly without impeding the current business model involved in online advertisement.","Title: Twitlang(er): Interactions Modeling Language (and Interpreter) for Twitter\nYear: 2015\n\nAbstract: Online social networks are widespread means to enact interactive collaboration among people by, e.g., planning events, diffusing information, and enabling discussions. Twitter provides one of the most illustrative example of how people can effectively interact without resorting to traditional communication media. For example, the platform has acted as a unique medium for reliable communication in emergency or for organising cooperative mass actions. This use of Twitter in a cooperative, possibly critical, setting calls for a more precise awareness of the dynamics regulating message spreading. To this aim, in this paper, we propose Twitlang, a formal language to model interactions among Twitter accounts. The operational semantics associated to the language allows users to clearly and precisely determine the effects of actions performed by Twitter accounts, such as post, retweet, reply-to or delete tweets. The language is implemented in the form of a Maude interpreter, Twitlanger, which takes a language term as an input and, automatically or interactively, explores the computations arising from the term. By relying on this interpreter, automatic verification of communication properties of Twitter accounts can be carried out via the analysis tools provided by the Maude framework. We illustrate the benefits of our executable formalisation by means of few simple, yet typical, examples of Twitter interactions, whose effects are somehow subtle.","Title: Spotting the diffusion of New Psychoactive Substances over the Internet.\nYear: 2016\n\nAbstract: Online availability and diffusion of New Psychoactive Substances (NPS) represent an emerging threat to healthcare systems. In this work, we analyse drugs forums, online shops, and Twitter. By mining the data from these sources, it is possible to understand the dynamics of drugs diffusion and their endorsement, as well as timely detecting new substances. We propose a set of visual analytics tools to support analysts in tackling NPS spreading and provide a better insight about drugs market and analysis.","Title: Semi-supervised knowledge extraction for detection of drugs and their effects.\nYear: 2016\n\nAbstract: New Psychoactive Substances (NPS) are drugs that lay in a grey area of legislation, since they are not internationally and officially banned, possibly leading to their not prosecutable trade. The exacerbation of the phenomenon is that NPS can be easily sold and bought online. Here, we consider large corpora of textual posts, published on online forums specialized on drug discussions, plus a small set of known substances and associated effects, which we call seeds. We propose a semi-supervised approach to knowledge extraction, applied to the detection of drugs (comprising NPS) and effects from the corpora under investigation. Based on the very small set of initial seeds, the work highlights how a contrastive approach and context deduction are effective in detecting substances and effects from the corpora. Our promising results, which feature a F1 score close to 0.9, pave the way for shortening the detection time of new psychoactive substances, once these are discussed and advertised on the Internet.","Title: Data Sharing Agreements: How to Glue Definition, Analysis and Mapping Together.\nYear: 2016\n\nAbstract: An electronic data sharing agreement (DSA) is a human-readable, yet machine-processable contract, regulating how organisations and/or individuals share data. Its smooth definition and fluid lifecycle management are key aspects for enabling data protection in various contexts, from e-government to the provision of business and healthcare services, for example.","Title: Social Fingerprinting - or the Truth About You.\nYear: 2016\n\nAbstract: Inspired by biological DNA, we model the behaviour of online users as \"Digital DNA\" sequences, introducing a strikingly novel, simple, and effective approach to discriminate between genuine and spambot online accounts.","Title: A Lifecycle For Data Sharing Agreements: How It Works Out\nYear: 2016\n\nAbstract: An electronic Data Sharing Agreement (DSA) is a humanreadable, yet machine-processable contract, regulating how organizations and/or individuals share data. In past work, we have shed light on DSA engineering, i.e., the process of studying how data sharing is ruled in traditional legal human-readable contracts and mapping their fields (and rules) into formats that are machine-processable, leading to the transposition of a traditional legal contract into the electronic DSA. However, the definition of an electronic DSA is only the starting point of a complex DSA lifecycle, driving the contract from its creation to (1) an analysis phase, where the DSA rules are checked against conflicts; and (2) a mapping phase, where the analysed rules are transposed into privacy policies expressed in enforceable languages. This paper presents our vision for the architectural definition of a DSA system, where a lifecycle manager orchestrates: an authoring tool for legal experts, policy experts, and end users; an analyser for checking consistency of the DSA rules; a mapper for encoding rules in a low level language amenable for enforcement.","Title: The paradigm-shift of social spambots: Evidence, theories, and tools for the arms race.\nYear: 2017\n\nAbstract: Recent studies in social media spam and automation provide anecdotal argumentation of the rise of a new generation of spambots, so-called social spambots. Here, for the first time, we extensively study this novel phenomenon on Twitter and we provide quantitative evidence that a paradigm-shift exists in spambot design. First, we measure current Twitter's capabilities of detecting the new social spambots. Later, we assess the human performance in discriminating between genuine accounts, social spambots, and traditional spambots. Then, we benchmark several state-of-the-art techniques proposed by the academic literature. Results show that neither Twitter, nor humans, nor cutting-edge applications are currently capable of accurately detecting the new social spambots. Our results call for new approaches capable of turning the tide in the fight against this raising phenomenon. We conclude by reviewing the latest literature on spambots detection and we highlight an emerging common research trend based on the analysis of collective behaviors. Insights derived from both our extensive experimental campaign and survey shed light on the most promising directions of research and lay the foundations for the arms race against the novel social spambots. Finally, to foster research on this novel phenomenon, we make publicly available to the scientific community all the datasets used in this study.","Title: A language-based approach to modelling and analysis of Twitter interactions.\nYear: 2017\n\nAbstract: More than a personal microblogging site, Twitter has been transformed by common use to an information publishing venue, which public characters, media channels and common people daily rely on for, e.g., news reporting and consumption, marketing, and social messaging. The use of Twitter in a cooperative and interactive setting calls for the precise awareness of the dynamics regulating message spreading. In this paper, we describe Twitlang, a language for modelling the interactions among Twitter accounts. The associated operational semantics allows users to precisely determine the effects of their actions on Twitter, such as post, reply-to or delete tweets. The language is implemented in the form of a Maude interpreter, Twitlanger, which takes a language term as an input and explores the computations arising from the term. By combining the strength of Twitlanger and the Maude model checker, it is possible to automatically verify communication properties of Twitter accounts. We illustrate the benefits of our executable formalisation by means of an application scenario inspired from real life. While the scenario highlights the benefits of adopting Twitter for a cooperative use in the everyday life, our analysis shows that appropriate settings are essential for a proper usage of the platform, in respect of fulfilling those communication properties expected within collaborative and interactive contexts.","Title: Social Fingerprinting: detection of spambot groups through DNA-inspired behavioral modeling.\nYear: 2018\n\nAbstract: Spambot detection in online social networks is a long-lasting challenge involving the study and design of detection techniques capable of efficiently identifying ever-evolving spammers. Recently, a new wave of social spambots has emerged, with advanced human-like characteristics that allow them to go undetected even by current state-of-the-art algorithms. In this paper, we show that efficient spam...","Title: Mining Worse and Better Opinions. Unsupervised and Agnostic Aggregation of Online Reviews.\nYear: 2017\n\nAbstract: In this paper, we propose a novel approach for aggregating online reviews, according to the opinions they express. Our methodology is unsupervised - due to the fact that it does not rely on pre-labeled reviews - and it is agnostic - since it does not make any assumption about the domain or the language of the review content. We measure the adherence of a review content to the domain terminology extracted from a review set. First, we demonstrate the informativeness of the adherence metric with respect to the score associated with a review. Then, we exploit the metric values to group reviews, according to the opinions they express. Our experimental campaign has been carried out on two large datasets collected from Booking and Amazon, respectively.","Title: Analysis Of Data Sharing Agreements\nYear: 2017\n\nAbstract: An electronic Data Sharing Agreement (DSA) is the machine-processable transposition of a traditional paper contract regulating data sharing among different organizations. DSA conveys different information, like the purpose of data sharing, the parties stipulating the contract, the kind of data, and a set of rules stating which actions are authorized, prohibited, and obliged on such data. Possibly edited by different actors from various perspectives - such as the legal and the business ones - a DSA could quite naturally include conflictual data sharing rules: the same data access request could be permitted according to some rules and denied according to others. Starting from the DSA definition, this paper describes the design of a DSA analysis framework and the development of the associated analysis tool. The DSA-Analyser proposed here evaluates the DSA rules by simulating all the possible contextual conditions, which may occur at access request time and which are linked to the vocabulary associated to the rules themselves. The output of the tool conveniently guides the editor, pointing to those rules, which are potentially conflicting, and highlighting the reasons leading to those conflicts. We have experimented the DSA-Analyser performances in terms of execution time, by varying the number of rules in the DSA, as well as the terms in the DSA vocabulary. Our findings highlight the capability of the analyser to deal with hundreds of rules and dozens of contexts in a reasonable amount of time. These results pave the way to the employment of the analyser in a real-use context.","Title: A study on text-score disagreement in online reviews.\nYear: 2017\n\nAbstract: In this paper, we focus on online reviews and employ artificial intelligence tools, taken from the cognitive computing field, to help understand the relationships between the textual part of the review and the assigned numerical score. We move from the intuitions that (1) a set of textual reviews expressing different sentiments may feature the same score (and vice-versa), and (2) detecting and analyzing the mismatches between the review content and the actual score may benefit both service providers and consumers, by highlighting specific factors of satisfaction (and dissatisfaction) in texts. To prove the intuitions, we adopt sentiment analysis techniques and we concentrate on hotel reviews, to find polarity mismatches therein. In particular, we first train a text classifier with a set of annotated hotel reviews, taken from the website. Then, we analyze a large dataset, with around 160k hotel reviews collected from , with the aim of detecting a polarity mismatch, indicating if the textual content of the review is in line, or not, with the associated score. Using well-established artificial intelligence techniques and analyzing in depth the reviews featuring a mismatch between the text polarity and the score, we find that—on a scale of five stars—those reviews ranked with middle scores include a mixture of positive and negative aspects. The approach proposed here, beside acting as a polarity detector, provides an effective selection of reviews—on an initial very large dataset—that may allow both consumers and providers to focus directly on the review subset featuring a text/score disagreement,which conveniently convey to the user a summary of positive and negative features of the review target.","Title: Exploiting Digital DNA for the Analysis of Similarities in Twitter Behaviours\nYear: 2017\n\nAbstract: Recently, DNA-inspired online behavioral modeling and analysis techniques have been proposed and successfully applied to a broad range of tasks. In this paper, we employ a DNA-inspired technique to investigate the fundamental laws that drive the occurrence of similarities among Twitter users. The achieved results are multifold. First, we demonstrate that, despite apparently showing little to no similarities, the online behaviors of Twitter users are far from being uniformly random. Then, we perform a set of simulations to benchmark different behavioral models and to identify the models that better resemble human behaviors in Twitter. Finally, we demonstrate that the number and the extent of behavioral similarities within a group of Twitter users obey a log-normal distribution. Our results shed light on the fundamental properties that drive behaviors of groups of Twitter users, through the lenses of DNA-inspired behavioral modeling techniques. Our datasets are publicly available to the scientific community to further explore analytics of online behaviors.","Title: Risk analysis of Android applications: A user-centric solution.\nYear: 2018\n\nAbstract: Android applications (apps) pose many risks to their users, e.g., by including code that may threaten user privacy or system integrity. Most of the current security countermeasures for detecting dangerous apps show some weaknesses, mainly related to users’ understanding and acceptance. Hence, users would benefit from an effective but simple technique that indicates whether an app is safe or risky to be installed. In this paper, we present MAETROID (Multi-criteria App Evaluator of TRust for AndrOID), a framework to evaluate the trustworthiness of Android apps, i.e., the amount of risk they pose to users, e.g., in terms of confidentiality and integrity. MAETROID performs a multi-criteria analysis of an app at deploy-time and returns a single easy-to-understand evaluation of the app’s risk level (i.e., Trusted, Medium Risk, and High Risk), aimed at driving the user decision on whether or not installing a new app. The criteria include the set of requested permissions and a set of metadata retrieved from the marketplace, denoting the app quality and popularity. We have tested MAETROID on a set of 11,000 apps both coming from Google Play and from a database of known malicious apps. The results show a good accuracy in both identifying the malicious apps and in terms of false positive rate.","Title: From Reaction to Proaction: Unexplored Ways to the Detection of Evolving Spambots.\nYear: 2018\n\nAbstract: We envisage a revolutionary change in the approach to spambot detection: instead of taking countermeasures only after having collected evidence of new spambot mischiefs, in a near future techniques will be able to anticipate the ever-evolving spammers.","Title: Who framed Roger Reindeer? De-censorship of Facebook posts by snippet classification.\nYear: 2018\n\nAbstract: This paper considers online news censorship and it concentrates on censorship of identities. Obfuscating identities may occur for disparate reasons, from military to judiciary ones. In the majority of cases, this happens to protect individuals from being identified and persecuted by hostile people. However, being the collaborative web characterised by a redundancy of information, it is not unusual that the same fact is reported by multiple sources, which may not apply the same restriction policies in terms of censorship. Also, the proven aptitude of social network users to disclose personal information leads to the phenomenon that comments to news can reveal the data withheld in the news itself. This gives us a mean to figure out who the subject of the censored news is. We propose an adaptation of a text analysis approach to unveil censored identities. The approach is tested on a synthesised scenario, which however resembles a real use case. Leveraging a text analysis based on a context classifier trained over snippets from posts and comments of Facebook pages, we achieve promising results. Despite the quite constrained settings in which we operate – such as considering only snippets of very short length – our system successfully detects the censored name, choosing among 10 different candidate names, in more than 50% of the investigated cases. This outperforms the results of two reference baselines. The findings reported in this paper, other than being supported by a thorough experimental methodology and interesting on their own, also pave the way for further investigation on the insidious issues of censorship on the web.","Title: Efficient Detection of Conflicts in Data Sharing Agreements.\nYear: 2017\n\nAbstract: This paper considers Data Sharing Agreements and their management as a key aspect for a secure, private and controlled access and usage of data. Starting from describing formats and languages for the agreements, we then focus on the design, development, and performance evaluation of an analysis tool, to spot potential conflicts within the data privacy policies constituting the agreement. The promising results achieved in terms of the execution time, by varying the number of rules in the agreements, and number of terms in the rules vocabulary, pave the way for the employment of the analyser in a real-use context.","Title: Contributions from ADBIS 2018 Workshops.\nYear: 2018\n\nAbstract: The ADBIS conferences provide an international forum for the presentation of research on database theory, development of advanced DBMS technologies, and their applications. The 22nd edition of ADBIS, held on September 2–5, 2018, in Budapest, Hungary, includes six thematic workshops collecting contributions from various domains representing new trends in the broad research areas of databases and information systems.","Title: An effective Decision Support System for social media listening based on cross-source sentiment analysis models.\nYear: 2019\n\nAbstract: Nowadays, companies and enterprises are more and more incline to exploit the pervasive action of on-line social media, such as Facebook, Twitter and Instagram. Indeed, several promotional and marketing campaigns are carried out by concurrently adopting several social medial channels. These campaigns reach very quickly a wide range of different categories of users, since many people spend most of their time on on-line social media during the day.","Title: Transparency in Keyword Faceted Search - An Investigation on Google Shopping.\nYear: 2019\n\nAbstract: The most popular e-commerce search engines allow the user to run a keyword search, to find relevant results and to narrow down the results by mean of filters. The engines can also keep track of data and activities of the users, to provide personalized content, thus filtering automatically out a part of the results. Issues occur when personalization is not transparent and interferes with the user choices. Indeed, it has been noticed that, in some cases, a different ordering of search results is shown to different users. This becomes particularly critical when search results are associated with prices. Changing the order of search results according to prices is known as price steering. This study investigates if and how price steering exists, considering queries on Google Shopping by users searching from different geographic locations, distinguishable by their values of Gross Domestic Product.","Title: A study on online travel reviews through intelligent data analysis.\nYear: 2018\n\nAbstract: The purpose of this paper is to show the application of a set of intelligent data analysis techniques to about 7 million of online travel reviews, with the aim of automatically extracting useful information. The reviews, collected from two popular online tourism-related review platforms, are all those posted by reviewers about one specific Italian location, from 2010 to 2017. To carry out the study, the following methodology is applied: a preliminary statistical analysis is performed to acquire general knowledge about the datasets, such as the geographical distribution of reviewers, their activities, and a comparison among the time of visits and the average scores of the reviews. Then, Natural Language Processing techniques are applied to extract and compare the most frequent words used in the two platforms. Finally, an Association Rule Learning algorithm is applied, to extract preferred destinations for distinct groups of reviewers, by mining interesting associations among the countries of origin of the reviewers and the most frequent destinations visited. By elaborating the available data, it is possible to automatically disclose valuable information for consumers and providers. The information automatically extracted can be exploited, for example, to build a recommender system for customers or a market analysis tool for service providers.","Title: Better Safe Than Sorry: An Adversarial Approach to Improve Social Bot Detection.\nYear: 2019\n\nAbstract: The arm race between spambots and spambot-detectors is made of several cycles (or generations): a new wave of spambots is created (and new spam is spread), new spambot filters are derived and old spambots mutate (or evolve) to new species. Recently, with the diffusion of the adversarial learning approach, a new practice is emerging: to manipulate on purpose target samples in order to make stronger detection models. Here, we manipulate generations of Twitter social bots, to obtain - and study - their possible future evolutions, with the aim of eventually deriving more effective detection techniques. In detail, we propose and experiment with a novel genetic algorithm for the synthesis of online accounts. The algorithm allows to create synthetic evolved versions of current state-of-the-art social bots. Results demonstrate that synthetic bots really escape current detection techniques. However, they give all the needed elements to improve such techniques, making possible a proactive approach for the design of social bot detection systems.","Title: On the capability of evolved spambots to evade detection via genetic engineering.\nYear: 2019\n\nAbstract: Since decades, genetic algorithms have been used as an effective heuristic to solve optimization problems. However, in order to be applied, genetic algorithms may require a string-based genetic encoding of information, which severely limited their applicability when dealing with online accounts. Remarkably, a behavioral modeling technique inspired by biological DNA has been recently proposed – and successfully applied – for monitoring and detecting spambots in Online Social Networks. In this so-called digital DNA representation, the behavioral lifetime of an account is encoded as a sequence of characters, namely a digital DNA sequence. In a previous work, the authors proposed to create synthetic digital DNA sequences that resemble the characteristics of the digital DNA sequences of real accounts. The combination of (i) the capability to model the accounts’ behaviors as digital DNA sequences, (ii) the possibility to create synthetic digital DNA sequences, and (iii) the evolutionary simulations allowed by genetic algorithms, open up the unprecedented opportunity to study – and even anticipate – the evolutionary patterns of modern social spambots. In this paper, we experiment with a novel ad-hoc genetic algorithm that allows to obtain behaviorally evolved spambots. By varying the different parameters of the genetic algorithm, we are able to evaluate the capability of the evolved spambots to escape a state-of-art behavior-based detection technique. Notably, despite such detection technique achieved excellent performances in the recent past, a number of our spambot evolutions manage to escape detection. Our analysis, if carried out at large-scale, would allow to proactively identify possible spambot evolutions capable of evading current detection techniques.","Title: The Role Of Bot Squads In The Political Propaganda On Twitter\nYear: 2019\n\nAbstract: Nowadays, Social Media are a privileged channel for news spreading, information exchange, and fact checking. Unexpectedly for many users, automated accounts, known as social bots, contribute more and more to this process of information diffusion. Using Twitter as a benchmark, we consider the traffic exchanged, over one month of observation, on the migration flux from Northern Africa to Italy. We measure the significant traffic of tweets only, by implementing an entropy-based null model that discounts the activity of users and the virality of tweets. Results show that social bots play a central role in the exchange of significant content. Indeed, not only the strongest hubs have a number of bots among their followers higher than expected, but furthermore a group of them, that can be assigned to the same political tendency, share a common set of bots as followers. The retweeting activity of such automated accounts amplifies the hubs' messages.","Title: On the efficacy of old features for the detection of new bots\nYear: 2021\n\nAbstract: For more than a decade now, academicians and online platform administrators have been studying solutions to the problem of bot detection. Bots are computer algorithms whose use is far from being benign: malicious bots are purposely created to distribute spam, sponsor public characters and, ultimately, induce a bias within the public opinion. To fight the bot invasion on our online ecosystem, several approaches have been implemented, mostly based on (supervised and unsupervised) classifiers, which adopt the most varied account features, from the simplest to the most expensive ones to be extracted from the raw data obtainable through the Twitter public APIs. In this exploratory study, using Twitter as a benchmark, we compare the performances of four state-of-art feature sets in detecting novel bots: one of the output scores of the popular bot detector Botometer, which considers more than 1,000 features of an account to take a decision; two feature sets based on the account profile and timeline; and the information about the Twitter client from which the user tweets. The results of our analysis, conducted on six recently released datasets of Twitter accounts, hint at the possible use of general-purpose classifiers and cheap-to-compute account features for the detection of evolved bots.","Title: Adversarial Machine Learning for Protecting Against Online Manipulation\nYear: 2022\n\nAbstract: Adversarial examples are inputs to a machine learning system that result in an incorrect output from that system. Attacks launched through this type of input can cause severe consequences: for example, in the field of image recognition, a stop signal can be misclassified as a speed limit indication. However, adversarial examples also represent the fuel for a flurry of research directions in different domains and applications. Here, we give an overview of how they can be profitably exploited as powerful tools to build stronger learning models, capable of better-withstanding attacks, for two crucial tasks: fake news and social bot detection.","Title: A Structured Analysis of Journalistic Evaluations for News Source Reliability.\nYear: 2022\n\nAbstract: In today's era of information disorder, many organizations are moving to verify the veracity of news published on the web and social media. In particular, some agencies are exploring the world of online media and, through a largely manual process, ranking the credibility and transparency of news sources around the world. In this paper, we evaluate two procedures for assessing the risk of online media exposing their readers to m/disinformation. The procedures have been dictated by NewsGuard and The Global Disinformation Index, two well-known organizations combating d/misinformation via practices of good journalism. Specifically, considering a fixed set of media outlets, we examine how many of them were rated equally by the two procedures, and which aspects led to disagreement in the assessment. The result of our analysis shows a good degree of agreement, which in our opinion has a double value: it fortifies the correctness of the procedures and lays the groundwork for their automation.","Title: ROMCIR 2022: Overview of the 2nd Workshop on Reducing Online Misinformation Through Credible Information Retrieval\nYear: 2022\n\nAbstract: The ROMCIR 2022 workshop is focused on discussing and addressing issues related to information disorder, a new term that holistically encompasses all forms of communication pollution. In particular, the aim of ROMCIR is reducing such clutter, from false content to incorrect correlations, from misinformation to disinformation, through Information Retrieval solutions, by providing users with access to genuine information. This topic is very broad, as it concerns different contents (e.g., Web pages, news, reviews, medical information, online accounts, etc.), different Web and social media platforms (e.g., microblogging platforms, social networking services, social question-answering systems, etc.), and different purposes (e.g., identifying false information, accessing and retrieving information based on its genuineness, providing explainable solutions to users, etc.). Therefore, interdisciplinary input to ROMCIR is more than welcome."],"string":"[\n \"Title: Evaluating the Trust of Android Applications through an Adaptive and Distributed Multi-criteria Approach\\nYear: 2013\\n\\nAbstract: New generation mobile devices, and their app stores, lack of a methodology to associate a level of trust to applications to faithfully represent their potential security risks. This problem is even more critical with newly published applications, for which either user reviews are missing or the number of downloads is still low. In this scenario, users may not fully estimate the risk associated with downloading apps found on on-line stores. Hence, here we propose a methodology for evaluating the trust level of an application through an adaptive, flexible, and dynamic framework. The evaluation of an application trust is performed using both static and dynamic parameters, which consider the application meta-data, its run-time behavior and the reports of users with respect to the software critical operations. We have validated the proposed approach by testing it on more than 180 real applications found both on official and unofficial markets by showing that it correctly categorizes applications as trusted or untrusted in 94% of the cases and it is resilient to poisoning attacks.\",\n \"Title: Authenticity in a reliable protocol for mobile computing\\nYear: 2003\\n\\nAbstract: We consider a known protocol for reliable multicast in distributed mobile systems where mobile hosts communicate with a wired infrastructure by means of wireless technology. The original specification of the protocol does not take into consideration any notion of computer security: an adversary may eavesdrop on communications between hosts and inject packets over the wireless links. We suggest a secured version of the protocol providing authenticity and integrity of packets over the wireless links. The secure mechanisms introduced rely on two different techniques: secure wireless channels and 1-time signature schemes. Further, we outline the formal verification of part of the secured protocol.\",\n \"Title: A prototype for solving conflicts in XACML-based e-Health policies.\\nYear: 2013\\n\\nAbstract: The Electronic Patient Record (EPR) enables the sharing of medical documents among several and widespread healthcare organizations. To guarantee privacy properties, access control policies should be defined, regulating how the documents can be shared. Conflicts may occur among policies applicable to the same access request. We present a running prototype, based on an XACML engine, that implements a conflict resolution strategy as an extension to the standard combining algorithms of the XACML engine. We evaluate the efficiency of our proposal in terms of execution time, on a variable number of conflicting rules.\",\n \"Title: Subjective review-based reputation\\nYear: 2012\\n\\nAbstract: The choice of a product or a service is often influenced by its reputation, which is usually calculated from existing reviews of this product or service. A review can be either objective, for instance when referring to concrete features of a product, or subjective, for instance when referring to the feeling of the reviewer about one aspect. Subjective reviews are potentially biased by the characteristics of the reviewers, and therefore two subjective reviews should not be treated equally. We propose in this paper a model of reputation compensating the subjective bias of di?erent categories of reviewers. We firstly calculate this bias by analyzing the ratio between reviews coming from different categories, and then we project a subjective reputation for a given category of reviewer. We demonstrate the accuracy of our bias calculation with an experimentation on public reviews for hotels, and two specific categories of users.\",\n \"Title: Formal Anaylsis of Some Timed Security Properties in Wireless Protocols\\nYear: 2003\\n\\nAbstract: We show how a recent language for the description of cryptographic protocols in a real time setting may be suitable to formally verify security aspects of wireless protocols. We define also a compositional proof rule for establishing security properties;of such protocols. The effectiveness of our approach is shown by defining and studying the timed integrity property for muTESLA, a well-known protocol for wireless sensor networks. We are able to deal with protocol specifications with an arbitrary number of agents (senders as well as receivers) running the protocol.\",\n \"Title: Formal Models and Analysis of Secure Multicast in Wired and Wireless Networks\\nYear: 2008\\n\\nAbstract: The spreading of multicast technology enables the development of group communication and so dealing with digital streams becomes more and more common over the Internet. Given the flourishing of security threats, the distribution of streamed data must be equipped with sufficient security guarantees. To this aim, some architectures have been proposed, to supply the distribution of the stream with guarantees of, e.g., authenticity, integrity, and confidentiality of the digital contents. This paper shows a formal capability of capturing some features of secure multicast protocols. In particular, both the modeling and the analysis of some case studies are shown, starting from basic schemes for signing digital streams, passing through protocols dealing with packet loss and time-synchronization requirements, concluding with a secure distribution of a secret key. A process-algebraic framework will be exploited, equipped with schemata for analysing security properties and compositional principles for evaluating if a property is satisfied over a system with more than two components.\",\n \"Title: On Relating and Integrating Two Trust Management Frameworks\\nYear: 2007\\n\\nAbstract: In this paper, we continue our line of research for defining an integrated framework for the specification and analysis of security and trust, aimed at providing the basis for the modeling and analysis of security and trust aspects of emergent dynamic coalitions (e.g., mobile ad hoc networks, peer to peer systems, web services). In particular, we consider two well-known languages: 1) the Role-based Trust-management framework (RT) and, in particular, its most basic language RT\\\"0, and 2) the transitive trust model, for defining trust and recommendation relationships. First, we show an encoding of the transitive trust model into part of RT\\\"0; then, this subset is mapped into the inference construct of the Crypto-CCS process algebra. Also, we introduce in the languages operators dealing with levels of trust. The relationships among these languages could allow us to model and analyze trust and recommendation issues in distributed systems by means of standard formal techniques, based on inference systems.\",\n \"Title: Formal analysis of some secure procedures for certificate delivery\\nYear: 2006\\n\\nAbstract: This paper describes and formally analyses two communication protocols that manage the secure emission of digital certificates. The formal analysis is carried out by means of a software tool for the automatic verification of cryptographic protocols with finite behaviour. The tool is able to discover, at a conceptual level, attacks against security procedures. The methodology is general enough to be applied to several kinds of cryptographic procedures and protocols. It is the opinion of the authors that this approach contributes towards a better understanding of the structure and aims of a protocol, for developers, analysers and final users. Copyright (C) 2005 John Wiley & Sons, Ltd.\",\n \"Title: Towards an executable algebra for product lines\\nYear: 2012\\n\\nAbstract: We propose the Controlled Language for Software Product Lines CL4SPL with the twofold aim of ensuring simplicity of use for product line engineers and safe translations to executable languages amenable for automated verification. We show an implementation of CL4SPL in Maude, a well-known rewrite engine, thus allowing formal analyses over product families specified with CL4SPL. We illustrate our approach with a toy family of coffee machines.\",\n \"Title: A Uniform Framework for Security and Trust Modeling and Analysis with Crypto-CCS\\nYear: 2007\\n\\nAbstract: In this paper, we present our line of research for defining an integrated framework for the specification and analysis of security and trust in complex and dynamic scenarios. We aim at showing how the same machinery applied for the formal verification of security protocols may be useful to model and analyze trust management procedures.\",\n \"Title: Modelling a Secure Agent with Team Automata\\nYear: 2006\\n\\nAbstract: We use Team Automata in order to model a protocol by Cachin et al. for securing agents in a hostile environment. Our study focuses on privacy properties of the agents. We use the framework to prove a result from the work by Cachin et al. As a by-product, our analysis gives some initial insight on the limits of the protocol. From a different perspective, this study continues a line of research on the expressive power and modelling capabilities of Team Automata. To the best of our knowledge, this is the first attempt to use Team Automata for the analysis of privacy properties.\",\n \"Title: SEAS: A Secure E-Voting Applet System\\nYear: 2003\\n\\nAbstract: This paper presents SEAS, the Secure E-voting Applet System, a protocol for implementing a secure and private system for polling over computer networks, usable in distributed organizations whose members may range up to dozens of thousands. We consider an architecture requiring the minimum number of servers involved in the validation and voting phases. Sensus, [7], a well known e-voting protocol, requires only two servers, namely a validator and a tallier. Even if satisfying most of the security requirements of an e-voting system, Sensus suffers of a vulnerability that allows one of the entities involved in the election process to cast its own votes in place of those that abstain from the vote. SEAS is a portable and flexible system that preserves the lightness of Sensus, but it avoids the mentioned weakness. We propose a prototype implementation of SEAS based on Java applet and XML technology.\",\n \"Title: Automated Analysis of Some Security Mechanisms of SCEP\\nYear: 2002\\n\\nAbstract: The paper analyzes SCEP, the Simple Certificate Enrollment Procedure, a two-way communication protocol to manage the secure emission of digital certificates to network devices. The protocol provides a consistent method of requesting and receiving certificates from different Certification Authorities by offering an open and scalable solution for deploying certificates which can be beneficial to all network devices and IPSEC software solutions.We formally analyze SCEP through a software tool for the automatic analysis of cryptographic protocols able to discover, at a conceptual level, attacks against security procedures. Our method of survey contributes towards a better understanding of the structure and aims of a protocol both for developers, analyzers and final users.\",\n \"Title: Signed and Weighted Trust Credentials in Fraglets.\\nYear: 2008\\n\\nAbstract: We continue our line of research by extending the Fraglets computation model with digital signature and security credentials dealing with a quantitative notion of trust. We also give a modeling example where trust credentials are managed at fraglets level.\",\n \"Title: Compositional Verification of Secure Streamed Data: A Case Study with EMSS\\nYear: 2003\\n\\nAbstract: We consider an instance of the EMSS protocol proposed in [19], authenticating streamed data in the presence of packet loss. We formally prove the integrity property of the instance by applying a compositional proof rule that allows us to check a specification with an arbitrary number of parallel processes. We argue that our approach may be applied to a wider class of stream signature protocols.\",\n \"Title: Executable Specification of Cryptofraglets in Maude for Security Verification.\\nYear: 2009\\n\\nAbstract: Fraglets are computation fragments flowing through a computer network. They implement a chemical reaction model where computations are carried out by having fraglets react with each other. The strong connection between their way of transforming and reacting and some formal rewriting system makes a fraglet program amenable to verification. Starting from a threat model which we intend to use for modeling secure communication protocols with fraglets, we propose an executable specification of fraglets (and fraglets-based cryptographic protocols) in the rewriting logic-based Maude interpreter.\",\n \"Title: Mobile Implementation and Formal Verification of an e-Voting System\\nYear: 2008\\n\\nAbstract: We propose a mobile implementation of an e-voting protocol. We also provide a formal analysis to validate a security property of our system.\",\n \"Title: A team automaton scenario for the analysis of security properties of communication protocols\\nYear: 2006\\n\\nAbstract: Formal methods are a popular means to specify and verify security properties of a variety of communication protocols. In this article we take a step towards the use of team automata for the analysis of security aspects in such protocols. To this aim, we define an insecure communication scenario for team automata that is general enough to encompass various communication protocols. We then reformulate the Generalized Non-Deducibility on Compositions schema -originally introduced in the context of process algebrae -in terms of team automata. Based on the resulting team automata framework, we subsequently develop two analysis strategies that can be used to verify security properties of communication protocols. Indeed, the paper concludes with two case studies in which we show how our framework can be used to prove integrity and secrecy in two different settings: We show how integrity is guaranteed in a team automaton model of a particular instance of the Efficient Multi-chained Stream Signature protocol, a communication protocol for signing digital streams that provides some robustness against packet loss, and we show how secrecy is preserved when a member of a multicast group leaves the group in a particular run of the complementary variable approach to the N-Root/Leaf pairwise keys protocol.\",\n \"Title: Team Automata for Security: - A Survey -.\\nYear: 2005\\n\\nAbstract: In [Kleijn, J., Team Automata for CSCW – A Survey –, Petri Net Technology for Communication-Based Systems—Advances in Petri Nets, LNCS 2472, Springer, 2003, 295–320], Kleijn presented a survey of the use of team automata for the specification and analysis of phenomena from the field of computer supported cooperative work, in particular notions related to groupware systems. In this paper we present a survey of the use of team automata for the specification and analysis of some issues from the field of security. In particular, we show how team automata can adequately be used to model and verify various access control policies, multicast/broadcast communication protocols, and general (cryptographic) communication protocols.\",\n \"Title: Combining declarative and procedural views in the specification and analysis of product families\\nYear: 2013\\n\\nAbstract: We introduce the feature-oriented language FLan as a proof of concept for specifying both declarative aspects of product families, namely constraints on their features, and procedural aspects, namely feature configuration and run-time behaviour. FLan is inspired by the concurrent constraint programming paradigm. A store of constraints allows one to specify in a declarative way all common constraints on features, including inter-feature constraints. A standard yet rich set of process-algebraic operators allows one to specify in a procedural way the configuration and behaviour of products. There is a close interaction between both views: (i) the execution of a process is constrained by its store to forbid undesired configurations; (ii) a process can query a store to resolve design and behavioural choices; (iii) a process can update the store by adding new features. An implementation in the Maude framework allows for a variety of formal automated analyses of product families specified in FLan, ranging from consistency checking to model checking.\",\n \"Title: A design phase for data sharing agreements\\nYear: 2011\\n\\nAbstract: The number of factories, service providers, retailers, and final users that create networks and establish collaborations for increasing their productivity and competitiveness is constantly growing, especially by effect of the globalization and outsourcing of industrial activities. This trend introduces new complexities in the value supply chain, not last the need for secure and private data sharing among the collaborating parties. A Data Sharing Agreement (DSA) represents a flexible means to assure privacy and security of electronic data exchange. DSA is a formal document regulating data exchange in a controlled manner, by defining a set of policies specifying what parties are allowed, or required, or denied to do with respect to data covered by the agreement. A key factor in the adoption of DSAs is their usability. Here, we propose an approach for a consistent and automated design phase of the agreements. In particular, we present an authoring tool for a user-friendly and cooperative editing of DSA and an analysis tool to identify possible conflicts or incompatibilities among the DSA policies.\",\n \"Title: Automated Synthesis and Ranking of Secure BPMN Orchestrators\\nYear: 2014\\n\\nAbstract: The authors describe a formal methodology for the automatic synthesis of a secure orchestrator for a set of BPMN processes. The synthesized orchestrator is able to guarantee that all the processes that are started reach their end, and the resulting orchestrator process is secure, that is, it does not allow the disclosure of certain secret messages. The authors present an implementation of a forth and back translation from BPMN to Crypto-CCS, that permits them to exploit the previously existing PaMoChSA tool to synthesize BPMN orchestrators. Furthermore, they study the problem of ranking orchestrators based on quantitative valuations of a process, the temporal evolution of such valuations, and their security, as a function of the knowledge of the attacker.\",\n \"Title: Discriminating Between The Wheat And The Chaff In Online Recommendation Systems\\nYear: 2014\\n\\nAbstract: MyChoice is an ambitious research project that aims to model, detect, and isolate outliers (aka fake) in online recommendation systems, as well as in online social networks. The final outcome of the project will be the prototype of an automated engine able to recognize fake information, such as reviews, and fake friends/followers, and able to filter out malicious material, in order to return reliable and genuine content to the user.\",\n \"Title: Compositional Verification of Integrity for Digital Stream Signature Protocols\\nYear: 2003\\n\\nAbstract: We investigate the application of concurrency theory notions as simulation relations and compositional proof rules for verifying digital stream signature protocols. In particular, we formally prove the integrity of the Gennaro-Rohatgi protocols in [7]. As a peculiarity, our technique is able to check a protocol with an unbounded number of parallel processes. We argue also that our approach may be applied to a wider class of stream signature protocols.\",\n \"Title: CNL4DSA: a controlled natural language for data sharing agreements\\nYear: 2010\\n\\nAbstract: A Data Sharing Agreement (DSA) is an agreement among contracting parties regulating how they share data. A DSA represents a flexible mean to assure privacy of data exchanged on the Web. As an example, a set of intelligent user agents may interact with each other, and by means of DSA, may negotiate privacy requirements on behalf of human users. However, a key factor for the adoption of privacy's technologies is not only their reliability, but also their usability. Here, we propose CNL4DSA, a Controlled Natural Language for DSA aiming at lowering the barrier to adoption of DSA, and, at the same time, ensuring mapping to formal languages that enable the automatic verification of agreements.\",\n \"Title: Fast certificate-based authentication scheme in multi-operator maintained wireless mesh networks\\nYear: 2010\\n\\nAbstract: In this paper, we consider QoS aware mesh networks that are maintained by multiple operators and they cooperate in the provision of networking services to the mesh clients. In order to support mobile users and seamless handover between the access points, the authentication delay has to be reduced. Many proposed fast authentication schemes rely on trust models that are not appropriate in a multi-operator environment. In this paper, we propose two certificate-based authentication schemes such that the authentication is performed locally between the access point and the mesh client. We assume that the access point is always a constrained device, and we propose different mechanisms for mesh clients with different computational performance. For constrained devices, we propose a mechanism where weak keys are used for digital signatures to decrease the latency of the authentication. The authenticity of the weak keys are provided by short-term certificates issued by the owner of the key. The short-term certificate has the digital signature generated by the owner's long-term key. We prove formally that the use of our weak key mechanism on the mesh client side is as secure as the use of some stronger keys. We perform a detailed performance evaluation on our proof-of-concept implementation, and we also compare our solution to the current standard methods.\",\n \"Title: SEAS, a secure e-voting protocol: Design and implementation\\nYear: 2005\\n\\nAbstract: This paper presents SEAS, the Secure E-voting Applet System, a protocol for implementing a secure system for polling over computer networks, usable in distributed organizations whose members may range up to dozens of thousands. We consider an architecture requiring the minimum number of servers involved in the validation and voting phases. Sensus, [Cranor L, Cytron RK. Sensor: a security-conscious electronic polling system for the internet. In: Proceedings of HICSS'97. IEEE; 1997. p. 561-70], a well-known e-voting protocol, requires only two servers, namely a validator and a tallier. Even if satisfying most of the security requirements of an e-voting system, Sensus suffers from a vulnerability that allows one of the entities involved in the election process to cast its own votes in place of those that abstain from the vote. SEAS is a portable and flexible system that preserves the limited number of servers of Sensus, but it avoids the mentioned vulnerability. We propose a prototype implementation of SEAS based on Java applet and XML technology.\",\n \"Title: A Formalization of Credit and Responsibility Within the GNDC Schema\\nYear: 2006\\n\\nAbstract: We formally define a notion of credit and responsibility within the Generalized Non Deducibility on Compositions framework. We investigate the validity of our definitions through some examples discussed in the literature.\",\n \"Title: Towards Security Analyses of an Identity Federation Protocol for Web Services in Convergent Networks\\nYear: 2007\\n\\nAbstract: We describe a formal approach to the analysis of security aspects of an identity federation protocol for web services in convergent networks. This network protocol was proposed by Telecom Italia as a solution to allow end users to access services on the web through different access networks without explicitly providing any credentials, while the service providers can trust the user's identity information provided by the access networks and access some user data. As a first step towards a full-blown formal security analysis of the protocol, we specify three user scenarios in the process algebra Crypto-CCS and verify the vulnerability of one of these specifications w.r.t. a man-in-the-middle attack with the model checker PaMoChSA.\",\n \"Title: Security and Trust Management: 8th International Workshop, STM 2012, Pisa, Italy, September 13-14, 2012, Revised Selected Papers\\nYear: 2013\\n\\nAbstract: This book constitutes the thoroughly refereed post-conference proceedings of the 8th International Workshop on Security and Trust Management, STM 2012, held in Pisa, Italy, in September 2012 - in conjunction with the 17th European Symposium Research in Computer Security (ESORICS 2012). The 20 revised full papers were carefully reviewed and selected from 57 submissions. The papers are organized into topical sections on policy enforcement and monitoring; access control; trust, reputation, and privacy; distributed systems and physical security; authentication and security policies.\",\n \"Title: Cryptofraglets Reloaded - Bioinspired Security Modeling of a RFID Protocol and Properties.\\nYear: 2014\\n\\nAbstract: Fraglets represent an execution model for communication protocols that resembles the chemical reactions in living organisms. The strong connection between their way of transforming and reacting and formal rewriting systems makes a fraglet program amenable to automatic verification. Starting from past work where the model has been enriched and executed to specify security protocols and properties (leading to the definition of cryptofraglets), this paper updates cryptofraglets and gives examples of concrete sample analyses over a secure RFID protocol.\",\n \"Title: Engineering the Lifecycle of Data Sharing Agreements.\\nYear: 2015\\n\\nAbstract: Sharing data among groups of organizations and/or individuals is essential in a modern web-based society, being at the very core of scientific and business transactions. Data sharing, however, poses several problems including trust, privacy, data misuse and/or abuse, and uncontrolled propagation of data. We describe an approach to preserve privacy whilst data sharing based on scientific Data Sharing Agreements (DSA).\",\n \"Title: A Lot Of Slots - Outliers Confinement In Review-Based Systems\\nYear: 2014\\n\\nAbstract: Review-based websites such as, e.g., Amazon, eBay, Trip-Advisor, and Booking have gained an extraordinary popularity, with millions of users daily consulting online reviews to choose the best services and products fitting their needs. Some of the most popular review-based websites rank products by sorting them aggregating the single ratings through their arithmetic mean. In contrast, recent studies have proved that the median is a more robust aggregator, in terms of ad hoc injections of outlier ratings. In this paper, we focus on four different types of ratings aggregators. We propose to the slotted mean and the slotted median, and we compare their mathematical properties with the mean and the median. The results of our experiments highlight advantages and drawbacks of relying on each of these quality indexes. Our experiments have been carried out on a large data set of hotel reviews collected from Booking. com, while our proposed solutions are rooted on sound statistical theory. The results shown in this paper, other than being interesting on their own, also call for further investigations.\",\n \"Title: Access Control Mechanisms For Fraglets\\nYear: 2007\\n\\nAbstract: The paper describes a revised version of Crypto-fraglets, and an enhancement of the framework with access control mechanisms. Fraglets is an interesting computing model that has connections with communication protocols, formal rewriting systems and biological systems. Indeed, fraglets basic mechanisms resemble bio-chemical reactions.\",\n \"Title: Crypto-fraglets: Networking, Biology and Security\\nYear: 2006\\n\\nAbstract: The paper describes connections between two models dealing with communication protocols, the fraglet model and the formal language of MultiSet Rewriting, which has very good inspiration from biology. By starting from similarities in their capabilities of modeling (indeed, their strong analogies in modeling biological systems), the programming language of the first model is translated into rule of the second model. Moreover, we propose an extended version of fraglets, namely Crypto-fraglets, as an initial step towards the intent of enlarging the set of communication protocols that this framework is currently able to describe, model and simulate.\",\n \"Title: An Expertise-Driven Authoring Tool for E-Health Data Policies\\nYear: 2014\\n\\nAbstract: Data sharing is crucial in many aspects of nowadays life, from economy to leisure, from public administration to healthcare. However, it implies several privacy issues that have to be managed. Definition of appropriate policies helps to safeguard the data privacy. This paper describes an expertise-driven authoring tool for privacy policies to be applied to the healthcare scenario. The tool exhibits two different interfaces, designed according to specific expertise of the policy authors. It is part of a general framework for editing, analysis, and enforcement of privacy policies. Furthermore, this serves as a first brick for a usability study on such tools.\",\n \"Title: Fame for sale: Efficient detection of fake Twitter followers.\\nYear: 2015\\n\\nAbstract: Fake followers are those Twitter accounts specifically created to inflate the number of followers of a target account. Fake followers are dangerous for the social platform and beyond, since they may alter concepts like popularity and influence in the Twittersphere—hence impacting on economy, politics, and society. In this paper, we contribute along different dimensions. First, we review some of the most relevant existing features and rules (proposed by Academia and Media) for anomalous Twitter accounts detection. Second, we create a baseline dataset of verified human and fake follower accounts. Such baseline dataset is publicly available to the scientific community. Then, we exploit the baseline dataset to train a set of machine-learning classifiers built over the reviewed rules and features. Our results show that most of the rules proposed by Media provide unsatisfactory performance in revealing fake followers, while features proposed in the past by Academia for spam detection provide good results. Building on the most promising features, we revise the classifiers both in terms of reduction of overfitting and cost for gathering the data needed to compute the features. The final result is a novel Class A classifier, general enough to thwart overfitting, lightweight thanks to the usage of the less costly features, and still able to correctly classify more than 95% of the accounts of the original training set. We ultimately perform an information fusion-based sensitivity analysis, to assess the global sensitivity of each of the features employed by the classifier.\",\n \"Title: A Matter Of Words: Nlp For Quality Evaluation Of Wikipedia Medical Articles\\nYear: 2016\\n\\nAbstract: Automatic quality evaluation of Web information is a task with many fields of applications and of great relevance, especially in critical domains, like the medical one. We move from the intuition that the quality of content of medical Web documents is affected by features related with the specific domain. First, the usage of a specific vocabulary (Domain Informativeness); then, the adoption of specific codes (like those used in the infoboxes of Wikipedia articles) and the type of document (e.g., historical and technical ones). In this paper, we propose to leverage specific domain features to improve the results of the evaluation of Wikipedia medical articles, relying on Natural Language Processing (NLP) and dictionaries-based techniques. The results of our experiments confirm that, by considering domain-oriented features, it is possible to improve existing solutions, mainly with those articles that other approaches have less correctly classified.\",\n \"Title: DNA-inspired online behavioral modeling and its application to spambot detection.\\nYear: 2016\\n\\nAbstract: A novel, simple, and effective approach to modeling online user behavior extracts and analyzes digital DNA sequences from user online actions and uses Twitter as a benchmark to test the proposal. Specifically, the model obtains an incisive and compact DNA-inspired characterization of user actions. Then, standard DNA analysis techniques discriminate between genuine and spambot accounts on Twitter. ...\",\n \"Title: Domain-Specific Queries And Web Search Personalization: Some Investigations\\nYear: 2015\\n\\nAbstract: Major search engines deploy personalized Web results to enhance users' experience, by showing them data supposed to be relevant to their interests. Even if this process may bring benefits to users while browsing, it also raises concerns on the selection of the search results. In particular, users may be unknowingly trapped by search engines in protective information bubbles, called \\\"filter bubbles\\\", which can have the undesired effect of separating users from information that does not fit their preferences. This paper moves from early results on quantification of personalization over Google search query results. Inspired by previous works, we have carried out some experiments consisting of search queries performed by a battery of Google accounts with differently prepared profiles. Matching query results, we quantify the level of personalization, according to topics of the queries and the profile of the accounts. This work reports initial results and it is a first step a for more extensive investigation to measure Web search personalization.\",\n \"Title: A quality model for social networks populated with web services\\nYear: 2015\\n\\nAbstract: This paper presents the development and evaluation of a $$\\\\mathcal {Q}$$Qo$$\\\\mathcal {SN}$$SN (standing for $$\\\\mathcal {Q}$$Quality of $$\\\\mathcal {S}$$Social $$\\\\mathcal {N}$$Network) model for social networks populated with Web services. These Web services are given the opportunity to select the networks in which they would like to sign in taking into account their concerns (in fact their providers' concerns) like better protection to their details and better exposure to potential users. To support Web services selection, the $$\\\\mathcal {Q}$$Qo$$\\\\mathcal {SN}$$SN model is built upon four criteria including robustness, trust, fairness, and traceability. The computation of these criteria uses a cryptographic technique known as secure multi-party computation. Different experiments showing how the networks react to Web services' actions (e.g., attack, join, and kick out) are also presented in the paper.\",\n \"Title: Towards safer information sharing in the cloud.\\nYear: 2015\\n\\nAbstract: Web interactions usually require the exchange of personal and confidential information for a variety of purposes, including enabling business transactions and the provisioning of services. A key issue affecting these interactions is the lack of trust and control on how data are going to be used and processed by the entities that receive it. In the traditional world, this problem is addressed using contractual agreements, those are signed by the involved parties, and law enforcement. This could be done electronically as well but, in addition to the trust issue, there is currently a major gap between the definition of legal contracts regulating the sharing of data, and the software infrastructure required to support and enforce them. How to enable organisations to provide more automation in this process? How to ensure that legal contracts can be actually enforced by the underlying IT infrastructure? How to enable end-users to express their preferences and constraints within these contracts? This article describes our R&D work to make progress towards addressing this gap via the usage of electronic Data Sharing Agreements (e-DSA). The aim is to share our vision, discuss the involved challenges and stimulate further research and development in this space. We specifically focus on a cloud scenario because it provides a rich set of use cases involving interactions and information sharing among multiple stakeholders, including users and service providers.\",\n \"Title: Bioinspired Security Analysis of Wireless Protocols.\\nYear: 2016\\n\\nAbstract: Fraglets represent an execution model for communication protocols that resembles the chemical reactions in living organisms. The strong connection between their way of transforming and reacting and formal rewriting systems makes a fraglet program amenable to automatic verification. Grounded on past work, this paper investigates feasibility of adopting fraglets as model for specifying security protocols and analysing their properties. In particular, we give concrete sample analyses over a secure RFID protocol, showing evolution of the protocol run as chemical dynamics and simulating an adversary trying to circumvent the intended steps. The results of our analysis confirm the effectiveness of the cryptofraglets framework for the model and analysis of security properties and eventually show its potential to identify and uncover protocol flaws.\",\n \"Title: Legal and Technical Perspectives in Data Sharing Agreements Definition.\\nYear: 2015\\n\\nAbstract: An electronic Data Sharing Agreement (DSA) is a human-readable, yet machine-processable contract, regulating how organizations and/or individuals share data. In this paper, we shed light on DSA engineering, i.e., the process of studying how data sharing is ruled in traditional legal human-readable contracts and mapping their fields (and rules) into formats that are machine-processable, leading to the transposition of the traditional contract into the electronic DSA. Tangible creation of the electronic DSA is possible through the design and implementation of a three-step DSA definition phase, with an associated authoring tool. The tool is specifically tailored for encoding not only the terms of law but also the rules that an organization may have put in place (e.g., corporate internal policies, or privacy policies, or data processing agreements) to manage the data, as well as end users’ privacy preferences.\",\n \"Title: VISIO: A Visual Approach for Singularity Detection in Recommendation Systems\\nYear: 2015\\n\\nAbstract: Reviews are a powerful decision-making tool for potential new customers, since they can significantly influence consumer purchase decisions, hence resulting in financial gains or losses for businesses. In striving for trustworthy review systems, validating reviews that could negatively or positively bias new customers is of utmost importance. To this goal, we propose VISIO: a visualization based representation of reviews that enables quick analysis and elicitation of interesting patterns and singularities. In fact, VISIO is meant to amplify cognition, supporting the process of singling out those reviews that require further analysis. VISIO is based on a theoretically sound approach, while its effectiveness and viability is demonstrated applying it to real data extracted from Tripadvisor and Booking.com.\",\n \"Title: Using Incentives To Analyze Social Web Services' Behaviors\\nYear: 2014\\n\\nAbstract: This paper discusses how incentives allow social networks to attract more members and reward those that are honest by retaining them. These members referred to as social Web services process users' requests in return for a certain usage fee and also expose certain behaviors in return of the incentives they receive. The usage fee is linked to a performance level that the social Web service needs to maintain at run time. In the case of any discrepancy between the usage fee and performance level the social Web service is expected to compensate users. However the compensation might not always take place. Simulation results illustrate why honesty is rewarding for social Web services, which has a positive impact on both their performance and the performance of the networks to which they belong.\",\n \"Title: 1st international workshop on TEchnical and LEgal aspects of data pRIvacy and SEcurity (TELERISE 2015)\\nYear: 2015\\n\\nAbstract: This paper is the report on the 1st International Workshop on TEchnical and LEgal aspects of data pRIvacy and SEcurity (TELERISE 2015) at the 37th International Conference on Software Engineering (ICSE 2015). TELERISE investigates privacy and security issues in data sharing from a technical and legal perspective. Keynote speech as well as selected papers presented at the event fit the topics of the workshop. This report gives the rationale of TELERISE and it provides a provisional program.\",\n \"Title: Visual detection of singularities in review platforms\\nYear: 2015\\n\\nAbstract: Product and service reviews can markedly influence consumer purchase decisions, leading to financial gains or losses for businesses. Therefore, there is a growing interest towards techniques for bringing out reviews that could negatively or positively bias new customers. To this goal, we propose a visual analysis of reviews that enables quick elicitation of interesting patterns and singularities. The proposed approach is based on a theoretically sound framework, while its effectiveness and viability is demonstrated by its application to real data extracted from Tripadvisor and Booking.com.\",\n \"Title: TRAP: Using Targeted ads to unveil Google personal profiles\\nYear: 2015\\n\\nAbstract: In the last decade, the advertisement market spread significantly in the web and mobile app system. Its effectiveness is also due thanks to the possibility to target the advertisement on the specific interests of the actual user, other than on the content of the website hosting the advertisement. In this scenario, became of great value services that collect and hence can provide information about the browsing user, like Facebook and Google. In this paper, we show how to maliciously exploit the Google Targeted Advertising system to infer personal information in Google user profiles. In particular, the attack we consider is external from Google and relies on combining data from Google AdWords with other data collected from a website of the Google Display Network. We validate the effectiveness of our proposed attack, also discussing possible application scenarios. The result of our research shows a significant practical privacy issue behind such type of targeted advertising service, and call for further investigation and the design of more privacy-aware solutions, possibly without impeding the current business model involved in online advertisement.\",\n \"Title: Twitlang(er): Interactions Modeling Language (and Interpreter) for Twitter\\nYear: 2015\\n\\nAbstract: Online social networks are widespread means to enact interactive collaboration among people by, e.g., planning events, diffusing information, and enabling discussions. Twitter provides one of the most illustrative example of how people can effectively interact without resorting to traditional communication media. For example, the platform has acted as a unique medium for reliable communication in emergency or for organising cooperative mass actions. This use of Twitter in a cooperative, possibly critical, setting calls for a more precise awareness of the dynamics regulating message spreading. To this aim, in this paper, we propose Twitlang, a formal language to model interactions among Twitter accounts. The operational semantics associated to the language allows users to clearly and precisely determine the effects of actions performed by Twitter accounts, such as post, retweet, reply-to or delete tweets. The language is implemented in the form of a Maude interpreter, Twitlanger, which takes a language term as an input and, automatically or interactively, explores the computations arising from the term. By relying on this interpreter, automatic verification of communication properties of Twitter accounts can be carried out via the analysis tools provided by the Maude framework. We illustrate the benefits of our executable formalisation by means of few simple, yet typical, examples of Twitter interactions, whose effects are somehow subtle.\",\n \"Title: Spotting the diffusion of New Psychoactive Substances over the Internet.\\nYear: 2016\\n\\nAbstract: Online availability and diffusion of New Psychoactive Substances (NPS) represent an emerging threat to healthcare systems. In this work, we analyse drugs forums, online shops, and Twitter. By mining the data from these sources, it is possible to understand the dynamics of drugs diffusion and their endorsement, as well as timely detecting new substances. We propose a set of visual analytics tools to support analysts in tackling NPS spreading and provide a better insight about drugs market and analysis.\",\n \"Title: Semi-supervised knowledge extraction for detection of drugs and their effects.\\nYear: 2016\\n\\nAbstract: New Psychoactive Substances (NPS) are drugs that lay in a grey area of legislation, since they are not internationally and officially banned, possibly leading to their not prosecutable trade. The exacerbation of the phenomenon is that NPS can be easily sold and bought online. Here, we consider large corpora of textual posts, published on online forums specialized on drug discussions, plus a small set of known substances and associated effects, which we call seeds. We propose a semi-supervised approach to knowledge extraction, applied to the detection of drugs (comprising NPS) and effects from the corpora under investigation. Based on the very small set of initial seeds, the work highlights how a contrastive approach and context deduction are effective in detecting substances and effects from the corpora. Our promising results, which feature a F1 score close to 0.9, pave the way for shortening the detection time of new psychoactive substances, once these are discussed and advertised on the Internet.\",\n \"Title: Data Sharing Agreements: How to Glue Definition, Analysis and Mapping Together.\\nYear: 2016\\n\\nAbstract: An electronic data sharing agreement (DSA) is a human-readable, yet machine-processable contract, regulating how organisations and/or individuals share data. Its smooth definition and fluid lifecycle management are key aspects for enabling data protection in various contexts, from e-government to the provision of business and healthcare services, for example.\",\n \"Title: Social Fingerprinting - or the Truth About You.\\nYear: 2016\\n\\nAbstract: Inspired by biological DNA, we model the behaviour of online users as \\\"Digital DNA\\\" sequences, introducing a strikingly novel, simple, and effective approach to discriminate between genuine and spambot online accounts.\",\n \"Title: A Lifecycle For Data Sharing Agreements: How It Works Out\\nYear: 2016\\n\\nAbstract: An electronic Data Sharing Agreement (DSA) is a humanreadable, yet machine-processable contract, regulating how organizations and/or individuals share data. In past work, we have shed light on DSA engineering, i.e., the process of studying how data sharing is ruled in traditional legal human-readable contracts and mapping their fields (and rules) into formats that are machine-processable, leading to the transposition of a traditional legal contract into the electronic DSA. However, the definition of an electronic DSA is only the starting point of a complex DSA lifecycle, driving the contract from its creation to (1) an analysis phase, where the DSA rules are checked against conflicts; and (2) a mapping phase, where the analysed rules are transposed into privacy policies expressed in enforceable languages. This paper presents our vision for the architectural definition of a DSA system, where a lifecycle manager orchestrates: an authoring tool for legal experts, policy experts, and end users; an analyser for checking consistency of the DSA rules; a mapper for encoding rules in a low level language amenable for enforcement.\",\n \"Title: The paradigm-shift of social spambots: Evidence, theories, and tools for the arms race.\\nYear: 2017\\n\\nAbstract: Recent studies in social media spam and automation provide anecdotal argumentation of the rise of a new generation of spambots, so-called social spambots. Here, for the first time, we extensively study this novel phenomenon on Twitter and we provide quantitative evidence that a paradigm-shift exists in spambot design. First, we measure current Twitter's capabilities of detecting the new social spambots. Later, we assess the human performance in discriminating between genuine accounts, social spambots, and traditional spambots. Then, we benchmark several state-of-the-art techniques proposed by the academic literature. Results show that neither Twitter, nor humans, nor cutting-edge applications are currently capable of accurately detecting the new social spambots. Our results call for new approaches capable of turning the tide in the fight against this raising phenomenon. We conclude by reviewing the latest literature on spambots detection and we highlight an emerging common research trend based on the analysis of collective behaviors. Insights derived from both our extensive experimental campaign and survey shed light on the most promising directions of research and lay the foundations for the arms race against the novel social spambots. Finally, to foster research on this novel phenomenon, we make publicly available to the scientific community all the datasets used in this study.\",\n \"Title: A language-based approach to modelling and analysis of Twitter interactions.\\nYear: 2017\\n\\nAbstract: More than a personal microblogging site, Twitter has been transformed by common use to an information publishing venue, which public characters, media channels and common people daily rely on for, e.g., news reporting and consumption, marketing, and social messaging. The use of Twitter in a cooperative and interactive setting calls for the precise awareness of the dynamics regulating message spreading. In this paper, we describe Twitlang, a language for modelling the interactions among Twitter accounts. The associated operational semantics allows users to precisely determine the effects of their actions on Twitter, such as post, reply-to or delete tweets. The language is implemented in the form of a Maude interpreter, Twitlanger, which takes a language term as an input and explores the computations arising from the term. By combining the strength of Twitlanger and the Maude model checker, it is possible to automatically verify communication properties of Twitter accounts. We illustrate the benefits of our executable formalisation by means of an application scenario inspired from real life. While the scenario highlights the benefits of adopting Twitter for a cooperative use in the everyday life, our analysis shows that appropriate settings are essential for a proper usage of the platform, in respect of fulfilling those communication properties expected within collaborative and interactive contexts.\",\n \"Title: Social Fingerprinting: detection of spambot groups through DNA-inspired behavioral modeling.\\nYear: 2018\\n\\nAbstract: Spambot detection in online social networks is a long-lasting challenge involving the study and design of detection techniques capable of efficiently identifying ever-evolving spammers. Recently, a new wave of social spambots has emerged, with advanced human-like characteristics that allow them to go undetected even by current state-of-the-art algorithms. In this paper, we show that efficient spam...\",\n \"Title: Mining Worse and Better Opinions. Unsupervised and Agnostic Aggregation of Online Reviews.\\nYear: 2017\\n\\nAbstract: In this paper, we propose a novel approach for aggregating online reviews, according to the opinions they express. Our methodology is unsupervised - due to the fact that it does not rely on pre-labeled reviews - and it is agnostic - since it does not make any assumption about the domain or the language of the review content. We measure the adherence of a review content to the domain terminology extracted from a review set. First, we demonstrate the informativeness of the adherence metric with respect to the score associated with a review. Then, we exploit the metric values to group reviews, according to the opinions they express. Our experimental campaign has been carried out on two large datasets collected from Booking and Amazon, respectively.\",\n \"Title: Analysis Of Data Sharing Agreements\\nYear: 2017\\n\\nAbstract: An electronic Data Sharing Agreement (DSA) is the machine-processable transposition of a traditional paper contract regulating data sharing among different organizations. DSA conveys different information, like the purpose of data sharing, the parties stipulating the contract, the kind of data, and a set of rules stating which actions are authorized, prohibited, and obliged on such data. Possibly edited by different actors from various perspectives - such as the legal and the business ones - a DSA could quite naturally include conflictual data sharing rules: the same data access request could be permitted according to some rules and denied according to others. Starting from the DSA definition, this paper describes the design of a DSA analysis framework and the development of the associated analysis tool. The DSA-Analyser proposed here evaluates the DSA rules by simulating all the possible contextual conditions, which may occur at access request time and which are linked to the vocabulary associated to the rules themselves. The output of the tool conveniently guides the editor, pointing to those rules, which are potentially conflicting, and highlighting the reasons leading to those conflicts. We have experimented the DSA-Analyser performances in terms of execution time, by varying the number of rules in the DSA, as well as the terms in the DSA vocabulary. Our findings highlight the capability of the analyser to deal with hundreds of rules and dozens of contexts in a reasonable amount of time. These results pave the way to the employment of the analyser in a real-use context.\",\n \"Title: A study on text-score disagreement in online reviews.\\nYear: 2017\\n\\nAbstract: In this paper, we focus on online reviews and employ artificial intelligence tools, taken from the cognitive computing field, to help understand the relationships between the textual part of the review and the assigned numerical score. We move from the intuitions that (1) a set of textual reviews expressing different sentiments may feature the same score (and vice-versa), and (2) detecting and analyzing the mismatches between the review content and the actual score may benefit both service providers and consumers, by highlighting specific factors of satisfaction (and dissatisfaction) in texts. To prove the intuitions, we adopt sentiment analysis techniques and we concentrate on hotel reviews, to find polarity mismatches therein. In particular, we first train a text classifier with a set of annotated hotel reviews, taken from the website. Then, we analyze a large dataset, with around 160k hotel reviews collected from , with the aim of detecting a polarity mismatch, indicating if the textual content of the review is in line, or not, with the associated score. Using well-established artificial intelligence techniques and analyzing in depth the reviews featuring a mismatch between the text polarity and the score, we find that—on a scale of five stars—those reviews ranked with middle scores include a mixture of positive and negative aspects. The approach proposed here, beside acting as a polarity detector, provides an effective selection of reviews—on an initial very large dataset—that may allow both consumers and providers to focus directly on the review subset featuring a text/score disagreement,which conveniently convey to the user a summary of positive and negative features of the review target.\",\n \"Title: Exploiting Digital DNA for the Analysis of Similarities in Twitter Behaviours\\nYear: 2017\\n\\nAbstract: Recently, DNA-inspired online behavioral modeling and analysis techniques have been proposed and successfully applied to a broad range of tasks. In this paper, we employ a DNA-inspired technique to investigate the fundamental laws that drive the occurrence of similarities among Twitter users. The achieved results are multifold. First, we demonstrate that, despite apparently showing little to no similarities, the online behaviors of Twitter users are far from being uniformly random. Then, we perform a set of simulations to benchmark different behavioral models and to identify the models that better resemble human behaviors in Twitter. Finally, we demonstrate that the number and the extent of behavioral similarities within a group of Twitter users obey a log-normal distribution. Our results shed light on the fundamental properties that drive behaviors of groups of Twitter users, through the lenses of DNA-inspired behavioral modeling techniques. Our datasets are publicly available to the scientific community to further explore analytics of online behaviors.\",\n \"Title: Risk analysis of Android applications: A user-centric solution.\\nYear: 2018\\n\\nAbstract: Android applications (apps) pose many risks to their users, e.g., by including code that may threaten user privacy or system integrity. Most of the current security countermeasures for detecting dangerous apps show some weaknesses, mainly related to users’ understanding and acceptance. Hence, users would benefit from an effective but simple technique that indicates whether an app is safe or risky to be installed. In this paper, we present MAETROID (Multi-criteria App Evaluator of TRust for AndrOID), a framework to evaluate the trustworthiness of Android apps, i.e., the amount of risk they pose to users, e.g., in terms of confidentiality and integrity. MAETROID performs a multi-criteria analysis of an app at deploy-time and returns a single easy-to-understand evaluation of the app’s risk level (i.e., Trusted, Medium Risk, and High Risk), aimed at driving the user decision on whether or not installing a new app. The criteria include the set of requested permissions and a set of metadata retrieved from the marketplace, denoting the app quality and popularity. We have tested MAETROID on a set of 11,000 apps both coming from Google Play and from a database of known malicious apps. The results show a good accuracy in both identifying the malicious apps and in terms of false positive rate.\",\n \"Title: From Reaction to Proaction: Unexplored Ways to the Detection of Evolving Spambots.\\nYear: 2018\\n\\nAbstract: We envisage a revolutionary change in the approach to spambot detection: instead of taking countermeasures only after having collected evidence of new spambot mischiefs, in a near future techniques will be able to anticipate the ever-evolving spammers.\",\n \"Title: Who framed Roger Reindeer? De-censorship of Facebook posts by snippet classification.\\nYear: 2018\\n\\nAbstract: This paper considers online news censorship and it concentrates on censorship of identities. Obfuscating identities may occur for disparate reasons, from military to judiciary ones. In the majority of cases, this happens to protect individuals from being identified and persecuted by hostile people. However, being the collaborative web characterised by a redundancy of information, it is not unusual that the same fact is reported by multiple sources, which may not apply the same restriction policies in terms of censorship. Also, the proven aptitude of social network users to disclose personal information leads to the phenomenon that comments to news can reveal the data withheld in the news itself. This gives us a mean to figure out who the subject of the censored news is. We propose an adaptation of a text analysis approach to unveil censored identities. The approach is tested on a synthesised scenario, which however resembles a real use case. Leveraging a text analysis based on a context classifier trained over snippets from posts and comments of Facebook pages, we achieve promising results. Despite the quite constrained settings in which we operate – such as considering only snippets of very short length – our system successfully detects the censored name, choosing among 10 different candidate names, in more than 50% of the investigated cases. This outperforms the results of two reference baselines. The findings reported in this paper, other than being supported by a thorough experimental methodology and interesting on their own, also pave the way for further investigation on the insidious issues of censorship on the web.\",\n \"Title: Efficient Detection of Conflicts in Data Sharing Agreements.\\nYear: 2017\\n\\nAbstract: This paper considers Data Sharing Agreements and their management as a key aspect for a secure, private and controlled access and usage of data. Starting from describing formats and languages for the agreements, we then focus on the design, development, and performance evaluation of an analysis tool, to spot potential conflicts within the data privacy policies constituting the agreement. The promising results achieved in terms of the execution time, by varying the number of rules in the agreements, and number of terms in the rules vocabulary, pave the way for the employment of the analyser in a real-use context.\",\n \"Title: Contributions from ADBIS 2018 Workshops.\\nYear: 2018\\n\\nAbstract: The ADBIS conferences provide an international forum for the presentation of research on database theory, development of advanced DBMS technologies, and their applications. The 22nd edition of ADBIS, held on September 2–5, 2018, in Budapest, Hungary, includes six thematic workshops collecting contributions from various domains representing new trends in the broad research areas of databases and information systems.\",\n \"Title: An effective Decision Support System for social media listening based on cross-source sentiment analysis models.\\nYear: 2019\\n\\nAbstract: Nowadays, companies and enterprises are more and more incline to exploit the pervasive action of on-line social media, such as Facebook, Twitter and Instagram. Indeed, several promotional and marketing campaigns are carried out by concurrently adopting several social medial channels. These campaigns reach very quickly a wide range of different categories of users, since many people spend most of their time on on-line social media during the day.\",\n \"Title: Transparency in Keyword Faceted Search - An Investigation on Google Shopping.\\nYear: 2019\\n\\nAbstract: The most popular e-commerce search engines allow the user to run a keyword search, to find relevant results and to narrow down the results by mean of filters. The engines can also keep track of data and activities of the users, to provide personalized content, thus filtering automatically out a part of the results. Issues occur when personalization is not transparent and interferes with the user choices. Indeed, it has been noticed that, in some cases, a different ordering of search results is shown to different users. This becomes particularly critical when search results are associated with prices. Changing the order of search results according to prices is known as price steering. This study investigates if and how price steering exists, considering queries on Google Shopping by users searching from different geographic locations, distinguishable by their values of Gross Domestic Product.\",\n \"Title: A study on online travel reviews through intelligent data analysis.\\nYear: 2018\\n\\nAbstract: The purpose of this paper is to show the application of a set of intelligent data analysis techniques to about 7 million of online travel reviews, with the aim of automatically extracting useful information. The reviews, collected from two popular online tourism-related review platforms, are all those posted by reviewers about one specific Italian location, from 2010 to 2017. To carry out the study, the following methodology is applied: a preliminary statistical analysis is performed to acquire general knowledge about the datasets, such as the geographical distribution of reviewers, their activities, and a comparison among the time of visits and the average scores of the reviews. Then, Natural Language Processing techniques are applied to extract and compare the most frequent words used in the two platforms. Finally, an Association Rule Learning algorithm is applied, to extract preferred destinations for distinct groups of reviewers, by mining interesting associations among the countries of origin of the reviewers and the most frequent destinations visited. By elaborating the available data, it is possible to automatically disclose valuable information for consumers and providers. The information automatically extracted can be exploited, for example, to build a recommender system for customers or a market analysis tool for service providers.\",\n \"Title: Better Safe Than Sorry: An Adversarial Approach to Improve Social Bot Detection.\\nYear: 2019\\n\\nAbstract: The arm race between spambots and spambot-detectors is made of several cycles (or generations): a new wave of spambots is created (and new spam is spread), new spambot filters are derived and old spambots mutate (or evolve) to new species. Recently, with the diffusion of the adversarial learning approach, a new practice is emerging: to manipulate on purpose target samples in order to make stronger detection models. Here, we manipulate generations of Twitter social bots, to obtain - and study - their possible future evolutions, with the aim of eventually deriving more effective detection techniques. In detail, we propose and experiment with a novel genetic algorithm for the synthesis of online accounts. The algorithm allows to create synthetic evolved versions of current state-of-the-art social bots. Results demonstrate that synthetic bots really escape current detection techniques. However, they give all the needed elements to improve such techniques, making possible a proactive approach for the design of social bot detection systems.\",\n \"Title: On the capability of evolved spambots to evade detection via genetic engineering.\\nYear: 2019\\n\\nAbstract: Since decades, genetic algorithms have been used as an effective heuristic to solve optimization problems. However, in order to be applied, genetic algorithms may require a string-based genetic encoding of information, which severely limited their applicability when dealing with online accounts. Remarkably, a behavioral modeling technique inspired by biological DNA has been recently proposed – and successfully applied – for monitoring and detecting spambots in Online Social Networks. In this so-called digital DNA representation, the behavioral lifetime of an account is encoded as a sequence of characters, namely a digital DNA sequence. In a previous work, the authors proposed to create synthetic digital DNA sequences that resemble the characteristics of the digital DNA sequences of real accounts. The combination of (i) the capability to model the accounts’ behaviors as digital DNA sequences, (ii) the possibility to create synthetic digital DNA sequences, and (iii) the evolutionary simulations allowed by genetic algorithms, open up the unprecedented opportunity to study – and even anticipate – the evolutionary patterns of modern social spambots. In this paper, we experiment with a novel ad-hoc genetic algorithm that allows to obtain behaviorally evolved spambots. By varying the different parameters of the genetic algorithm, we are able to evaluate the capability of the evolved spambots to escape a state-of-art behavior-based detection technique. Notably, despite such detection technique achieved excellent performances in the recent past, a number of our spambot evolutions manage to escape detection. Our analysis, if carried out at large-scale, would allow to proactively identify possible spambot evolutions capable of evading current detection techniques.\",\n \"Title: The Role Of Bot Squads In The Political Propaganda On Twitter\\nYear: 2019\\n\\nAbstract: Nowadays, Social Media are a privileged channel for news spreading, information exchange, and fact checking. Unexpectedly for many users, automated accounts, known as social bots, contribute more and more to this process of information diffusion. Using Twitter as a benchmark, we consider the traffic exchanged, over one month of observation, on the migration flux from Northern Africa to Italy. We measure the significant traffic of tweets only, by implementing an entropy-based null model that discounts the activity of users and the virality of tweets. Results show that social bots play a central role in the exchange of significant content. Indeed, not only the strongest hubs have a number of bots among their followers higher than expected, but furthermore a group of them, that can be assigned to the same political tendency, share a common set of bots as followers. The retweeting activity of such automated accounts amplifies the hubs' messages.\",\n \"Title: On the efficacy of old features for the detection of new bots\\nYear: 2021\\n\\nAbstract: For more than a decade now, academicians and online platform administrators have been studying solutions to the problem of bot detection. Bots are computer algorithms whose use is far from being benign: malicious bots are purposely created to distribute spam, sponsor public characters and, ultimately, induce a bias within the public opinion. To fight the bot invasion on our online ecosystem, several approaches have been implemented, mostly based on (supervised and unsupervised) classifiers, which adopt the most varied account features, from the simplest to the most expensive ones to be extracted from the raw data obtainable through the Twitter public APIs. In this exploratory study, using Twitter as a benchmark, we compare the performances of four state-of-art feature sets in detecting novel bots: one of the output scores of the popular bot detector Botometer, which considers more than 1,000 features of an account to take a decision; two feature sets based on the account profile and timeline; and the information about the Twitter client from which the user tweets. The results of our analysis, conducted on six recently released datasets of Twitter accounts, hint at the possible use of general-purpose classifiers and cheap-to-compute account features for the detection of evolved bots.\",\n \"Title: Adversarial Machine Learning for Protecting Against Online Manipulation\\nYear: 2022\\n\\nAbstract: Adversarial examples are inputs to a machine learning system that result in an incorrect output from that system. Attacks launched through this type of input can cause severe consequences: for example, in the field of image recognition, a stop signal can be misclassified as a speed limit indication. However, adversarial examples also represent the fuel for a flurry of research directions in different domains and applications. Here, we give an overview of how they can be profitably exploited as powerful tools to build stronger learning models, capable of better-withstanding attacks, for two crucial tasks: fake news and social bot detection.\",\n \"Title: A Structured Analysis of Journalistic Evaluations for News Source Reliability.\\nYear: 2022\\n\\nAbstract: In today's era of information disorder, many organizations are moving to verify the veracity of news published on the web and social media. In particular, some agencies are exploring the world of online media and, through a largely manual process, ranking the credibility and transparency of news sources around the world. In this paper, we evaluate two procedures for assessing the risk of online media exposing their readers to m/disinformation. The procedures have been dictated by NewsGuard and The Global Disinformation Index, two well-known organizations combating d/misinformation via practices of good journalism. Specifically, considering a fixed set of media outlets, we examine how many of them were rated equally by the two procedures, and which aspects led to disagreement in the assessment. The result of our analysis shows a good degree of agreement, which in our opinion has a double value: it fortifies the correctness of the procedures and lays the groundwork for their automation.\",\n \"Title: ROMCIR 2022: Overview of the 2nd Workshop on Reducing Online Misinformation Through Credible Information Retrieval\\nYear: 2022\\n\\nAbstract: The ROMCIR 2022 workshop is focused on discussing and addressing issues related to information disorder, a new term that holistically encompasses all forms of communication pollution. In particular, the aim of ROMCIR is reducing such clutter, from false content to incorrect correlations, from misinformation to disinformation, through Information Retrieval solutions, by providing users with access to genuine information. This topic is very broad, as it concerns different contents (e.g., Web pages, news, reviews, medical information, online accounts, etc.), different Web and social media platforms (e.g., microblogging platforms, social networking services, social question-answering systems, etc.), and different purposes (e.g., identifying false information, accessing and retrieving information based on its genuineness, providing explainable solutions to users, etc.). Therefore, interdisciplinary input to ROMCIR is more than welcome.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":77,"string":"77"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":253,"string":"253"}}},{"rowIdx":254,"cells":{"question_id":{"kind":"string","value":"Jindi Wang"},"question":{"kind":"string","value":"Generate an abstract for the title \"Using Crop Simulation Model To Study The Time Lag Between Precipitation And Ndvi And Its Effect On Ndvi Based Agricultural Applications\" using the following items: NDVI, time lag, precipitation, CERES-Wheat model, agricultural applications."},"answer":{"kind":"string","value":"One of the problems in normalized difference vegetation index (NDVI) based agricultural applications is the time lag between precipitation and NDVI. In this study, the CERES-Wheat model under decision support system for agrotechnology transfer shell was used to simulate the time lag between precipitation and NDVI under rainfed conditions in the Guanzbong, Plain, China. The results showed that there were about 14 to 37 days' time lags between precipitation and NDVI, and the time lags depended on the growing stages of winter wheat. The time lag was about 14 days at the crop's tasselling stage, while it was about 37 days for the crop's reviving stage. The results also indicated that there were year to year variations of the time lags and the time lag should be considered for NDVI based agricultural applications."},"correct_answer":{"kind":"string","value":"One of the problems in normalized difference vegetation index (NDVI) based agricultural applications is the time lag between precipitation and NDVI. In this study, the CERES-Wheat model under decision support system for agrotechnology transfer shell was used to simulate the time lag between precipitation and NDVI under rainfed conditions in the Guanzbong, Plain, China. The results showed that there were about 14 to 37 days' time lags between precipitation and NDVI, and the time lags depended on the growing stages of winter wheat. The time lag was about 14 days at the crop's tasselling stage, while it was about 37 days for the crop's reviving stage. The results also indicated that there were year to year variations of the time lags and the time lag should be considered for NDVI based agricultural applications."},"documents":{"kind":"list like","value":["Title: A Simple Interpretation Of Ndvi-Ts Space Combining - Lai And Evapotranspiration\nYear: 2004\n\nAbstract: The paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and analyzing transformation condition and the physical connotation and ecological meaning of the vegetation index-surface temperature feature space. Further, using the Temperature-Vegetation Dryness Index (TVDI), we explain the existent meaning of a triangular shape after NDVI arrives at saturated state (NDVI=1) by analyzing the relationship between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts will help us validate and update land surface models well.","Title: Land surface leaf area index estimation based on time series multi-angular remote sensing data\nYear: 2013\n\nAbstract: Time series leaf area index (LAI) derived from remote sensing data is a key parameter for environment researches especially on dynamic changes of land surface. In this study, a new approach was developed to retrieve LAI from time series Moderate Resolution Imaging Spectroradiometer (MODIS) multi-angular remote sensing data. Based on radiative transfer theory, we used Ross Thick-Li Sparse Reciprocal (RTLSR) kernel driven model to generate specific directional BRFs and corresponding anisotropy information, employed Scattering by Arbitrarily Inclined Leaves with Hotspot (SAILH) model to fill in missing data and Data-Based Mechanistic modeling (DBM) procedure to model and estimate time series vegetation LAI. The preliminary results indicated that the LAIs derived in this study have good agreement with ground LAI measurements and their continuity of the time series are superior to MODIS LAI product.","Title: Landscape structure based super-resolution mapping from remotely sensed imagery\nYear: 2011\n\nAbstract: Spatial resolution is one of the central issues in land cover mapping from remote sensing imagery, and sub-pixel land cover mapping is difficult and challenging in this domain. Soft classification can provide more information than hard classification. However, the spatial location of land cover compositions within each pixel is unknown. To solve this problem, super-resolution mapping methods have been developed in recent years. In this paper, a landscape structure based approach for super-resolution land cover mapping is introduced to generate super-resolution land cover maps from remote sensing data. The method was used to map simulated target images and a real landscape and the results indicate that this approach has the ability to reconstruct complicated landscape with linear features, and large or small patches relative to the pixel size.","Title: Estimating leaf area index by coupling radiative transfer model and a dynamic model from multi-source remote sensing data\nYear: 2009\n\nAbstract: Satellite remote sensing enables derivation of LAI globally at available spatial resolution and temporal frequency, and several LAI products have been produced. However, there are problems for the current global or regional LAI products, which restrict the application of these products. On the one hand, there are gaps between the large number of parameters of physical models and the small amount of data obtained by single sensor, which may cause the decrease in accuracy that LAI products should have. On the other hand, there are gaps between instantaneous observation of remote sensing and parameters which have change rules. Custom methods to retrieve LAI from remote sensing data are just involving the transient observations, discarding the information about process. To resolve these problems, we develop a methodology to retrieve LAI by involving diverse data from multiple sensor and LAI change rule. The methodology can take full advantage of the different band and angle information of time series MODIS and MISR data to improve the accuracy of the retrieved LAI over the MODIS LAI product compared to the field measured LAI data. And the retrieved LAI is also temporally continuous.","Title: Study On The Albedo Of Winter Wheat At Growing Period With Different Spatial Scales\nYear: 2004\n\nAbstract: This paper presents a general method and some preliminary results on validating MODIS albedo products, and how albedo changedingy in the winter-wheat's growing period. The available albedo observations are with different scales, including ground measurements and MODIS Albedo products. The study results show that the winter wheat's albedo of both the satellite observation scale anti ground measurements scale have the same trend at every growth stage.","Title: Retrieval of forest canopy LAI directly from airborne full-waveform lidar data\nYear: 2013\n\nAbstract: Forest canopy LAI is an important variable to the modeling of energy over regional and global scales. This paper explored the method to retrieve LAI and FAVD directly from full-waveform LiDAR data. At first, he full-waveform LiDAR data, including emitting and return laser waves, were denoised and decomposed. Based on the interaction model between LiDAR and forest, and the parameters of Gaussian decomposition, the forest FAVD was then inverted. Besides, the missing LiDAR data caused by high density forest and LiDAR system restrictions was filled based on the existing LiDARdata and CHM. At last, LAI of the research area was retrieved from the inversed FAVD, and validated by the LAI field measurement (r = 0.73, RMSE = 0.67).","Title: The Bidirectional Reflectance Signature of Typical Land Surfaces and Comparison of MISR and MODIS BRDF Products\nYear: 2008\n\nAbstract: The bidirectional reflectance distribution function (BRDF) of land surfaces specifies the behavior of surface directional reflectance as a function of illumination and viewing angles. The Moderate resolution Imaging Spectroradiometer (MODIS) and The Multiangle Imaging Spectroradiometer (MISR) provide their BRDF model parameters products respectively. Since the BRDF model parameters products are inverted from the observations with limited viewing directions for a given pixel, it is necessary to evaluate whether they can effectively characterize the directional reflectance in other viewing directions. In this study, we choose BRDF products data on four land cover types to learn their bidirectional reflectance signatures and to analyze the representation of MISR and MODIS BRDF model parameters products. The results show that: the MISR BRDF product shows hot spot more clearly than MODIS product, and both BRDF models' representative ability for extrapolating the reflectance at those directions without viewing dada tends to weaken when the viewing zenith angle increases.","Title: Application of red edge variables in winter wheat nutrition diagnosis\nYear: 2004\n\nAbstract: Remote sensing offers the potential to determine rapidly the physiological condition of crop over large areas. Canopy reflectance data selected at key growth stages of winter wheat were analyzed. It indicated that winter wheat growth phonological changes can be evaluated by red edge variables (REV) characteristics. Regression equations between chlorophyll concentration, nitrogen concentration, soluble sugar were established, prediction of foliar soluble sugar and chlorophyll concentration by red edge position, foliar nitrogen concentration by the amplitude of red edge, starch concentration by the near infrared plateau, leaf area index by the area of red edge peak are successful and feasible. For this purpose red edge variables can play a vital role in providing time-specific and time-critical information for precision farming, due to their capabilities in measuring canopy spectrum variability","Title: A Temporally Integrated Inversion Method for Estimating Leaf Area Index From MODIS Data\nYear: 2009\n\nAbstract: Multiple leaf area index (LAI) products have been generated from remote-sensing data. Among them, the Moderate-Resolution Imaging Spectroradiometer (MODIS) LAI product (MOD15A2) is now routinely derived from data acquired by MODIS sensors onboard Terra and Aqua satellite platforms. However, the MODIS LAI product is not spatially and temporally continuous and is inaccurate in many areas for some vegetation types. In this paper, a new algorithm is developed to estimate LAI from time-series MODIS reflectance data (MOD09A1). A radiative-transfer model is coupled with a double-logistic LAI temporal-profile model, and the shuffled complex evolution optimization method, developed at the University of Arizona, is used to estimate the parameters of the coupled model from the temporal signature in a given time window. Preliminary analysis using MODIS surface-reflectance data at flux sites was performed to validate this method. The results show that the new algorithm is able to construct a temporally continuous LAI product efficiently, and the accuracy has been significantly improved over the MODIS LAI product as compared to field-measured LAI data.","Title: A Brief Introduction To The Standardized Spectral Database Of Typical Ground Objects\nYear: 2004\n\nAbstract: The construction of standardized spectral database for typical objects of land surface aims to push development and application of quantitative remote sensing. The database is composed of four main parts including spectral database, model database, prior knowledgebase, and image database. The spectral database contains collection of existed spectral data, with quality evaluation, and collection of new spectral data together with corresponding parameters based on the new standard and criterion. The image database mainly contains a set of typical pica image data, which are synchronous to the ground spectral measurements obtained by different sensors. The prior, knowledgebase widely includes such as data of LULC in different scales, DEM data, phenology data etc.. The model database mainly contains models for spectral simulation, and includes also some general models for processing images. The model database is a key part of the spectral database. Though model simulation, database can provide characteristic spectral curves in different phases, scales and states. Furthermore, this database also includes demonstration of typical applications, which can make user to master application method of database quickly and exploit the application field of spectral database according to the detailed requirements. The construction of spectral database mainly provide some functions according to different users as follows: user management, upload and download of spectral data, management and transfer of prior knowledge, query of spectral data and corresponding parameters, model computing, query of remote sensing image, application demonstration, system management, user communication and so on.. The core product of database is to provide measured and simulated spectral data of typical ground objects.","Title: Modeling directional effects from nonisothermal land surfaces in wideband thermal infrared measurements\nYear: 2001\n\nAbstract: We present an algorithm to retrieve land surface temperatures from wideband thermal infrared measurements using the model of Li et al. (1999). Forward simulation and inversion demonstrates the method to be stable in the presence of observation noise. Results from inversions performed using field measurements show that errors are generally less than the uncertainty in the observations","Title: Study On Scale Scope And Regional Consistency Of Earth Scene Heterogeneity\nYear: 2004\n\nAbstract: ln our former research, we raised the concept of histo-variogram to describe the spatial heterogeneity among the earth objects compactly based on the analysis of the characteristics of other spatial analyzing methods such as variogram, information entropy. Just like all the other nature phenomenon, the spatial heterogeneity is also scale depended. That is, the heterogeneity of one kind of earth scene at a certain scale may become homogeneous at the other scale and vice versa. In current research, we want to find: 1. if there exists one scale scope in which the heterogeneity keeps relative stabilization. 2. if the heterogeneity of specific earth scent has regional coherence. This is very important for model selection or parameter adjustaion during inversion of quantitative remote sensing. We use the concept of \"total fractal dimension\" that rose in our former research to measure the hetero-eneitv of earth scene. The data source we used is stochastic sampled sub-regions from LUCC of Beijing district with different scales. The preparatory result shows that the heterogeneity of different earth scene has its specific scale scope and heterogeneity of most earth scenes have regional coherence.","Title: Comparison of Radiative Transfer Models for Simulating Snow Surface Thermal Infrared Emissivity\nYear: 2010\n\nAbstract: In this study, three analytical radiative transfer (RT) models and a numerical RT model are used to simulate the thermal-infrared (8-13 μm) emissivity spectra of snow surfaces. The single-scattering albedo and asymmetry factor calculated by Mie theory, in conjunction with that modified by two existing packing correction methods, are used as inputs to these RT models. The simulated snow emissivity spectra are compared with in situ measurements. The best models for simulating snow emissivity spectra are identified at the conclusion of this paper.","Title: An approach on improving MODIS albedo product by using the information from MODIS LAI product\nYear: 2012\n\nAbstract: Surface albedo is an important parameter in modeling climate processes as it determines the energy budget of the earth's surface. Operational surface albedo products are available from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. However, due to the factors associated with weather, sensors and algorithms, albedo products from satellite observations often have many gaps. In this paper, we reformed the semi-empirical kernel-driven model to express the relation between the bidirectional reflectance distribution function (BRDF) and the Leaf Area Index (LAI). Within a small region, the soil properties under plant canopies are similar, therefore the reflectance is unanimous. When the land cover types are identical and the LAI values are same, the canopy top reflectance should be same. Thus, within a small region, the pixels of same properties have the same reflectance. For one pixel, if the MODIS albedo product has no retrieval but MODIS LAI product has high quality retrieval, the LAI information can be used to filled the MODIS albedo data gaps. A comparison indicates that the filled data conform well with the in-situ measurements albedo.","Title: Study On Forest Vegetation Classification Based On Multi-Temporal Remote Sensing Images\nYear: 2008\n\nAbstract: It is very difficult to classify forest vegetation in mountain areas because of the impact of complex terrain. A new method, classification of forest vegetation based on multi-temporal remote sensing, is proposed in this paper. The forest vegetation could get better classification precision by avoiding the interactions of different plants with multi-temporal images. So it enhanced the separability of coniferous forest and broad leaf forest. The classification result showed that the accuracy Could be greatly improved by using multi-temporal remote sensing images. The overall accuracy and kappa coefficient were 81.3% and 0.72, respectively. So the method delivered in this essay has obviously technological advantages and important application potentiality in forest vegetation classification.","Title: Kernel -based vegetation index and its validation with different-scale BRDF data sets.\nYear: 2004\n\nAbstract: Traditional vegetation indices are usually constructed by using red and near-infrared band reflectance data under single solar incidence-observation geometry. However, because of the anisotropy of the earth surface's reflectance, vegetation indices acquired from different solar- incidence observation geometries exhibit lots of variances. Meanwhile, most of those indices only utilize vegetation's spectral information, and anisotropic reflectance of vegetation is considered as a disturbing factor rather than a source of vegetation's structural information. In this paper, kernel-based vegetation index (KVI) is constructed based on the semi-empirical kernel-based BRDF model parameters. Validation results of ground measured bidirectional reflection data of different vegetation types show: kernel-based vegetation index has better linear relationship with corresponding vegetation's leaf area index (LAI) than widely used normalized difference vegetation index does. The results of upscaling KVI from local scale to global large scale suggests the effect of scale needs to be considered when using it to different scale data sets. This study suggests that KVI provides a new method of better using multi-spectrum and multi-angle reflectance data, and has certain potential for multi-angular remote sensing applications.","Title: Comparison and analysis of two fractal dimension computing algorithms for upscaling remote sensing Leaf Area Index map\nYear: 2012\n\nAbstract: The Leaf Area Index (LAI) values derived from remote sensing images with different resolutions can be different, because of the heterogeneity of land surface. To validate the coarse resolution LAI product, the in situ LAI measurements and the high resolution LAI map need to be upscaled to the coarse resolution(such as 1 km). As the principle of fractal geometry has been applied to describe the irregular distribution of vegetation, the measured LAI can be upscaled using Fractal Dimension (FD) which is the key parameter of fractal geometry. In this paper two FD computing algorithms, Triangular Prism Surface Area method (TPSA) and Differential Box Counting algorithm (DBC), were compared in two aspects. One aspect was the ability of describing heterogeneity of LAI in different landscapes; another was the spatial distribution of FD and upscaled LAI. The log-log curves of computing algorithms showed that TPSA performs better to capture the difference between different landscapes than DBC algorithm does. Also TPSA can detect the scale inflexion of LAI spatial distribution but the DBC can't. The pattern of FD and upscaled LAI map using TPSA is similar with the real pattern of vegetation, while the FD and upscaled LAI map using DBC algorithm cannot capture the real pattern of vegetation.","Title: Comparison of the inversion ability in extrapolating forest canopy height by integration of LiDAR data and different optical remote sensing products\nYear: 2012\n\nAbstract: Forest canopy height is an important variable to the modeling of energy over regional and global scales. This paper first examined the relationship between field-surveyed canopy height and LiDAR-derived canopy height, regression between them had an RMSE and R2 value of 0.94 m and 0.64. To extrapolate the LiDAR height to a continuous area, we compared the ability of four sources of optical remote sensing data (MODIS BRFs, MODIS NBAR, MISR and SPOT data) in predicting the LiDAR measured canopy height. Multivariate linear regression and single variable nonlinear regression models were developed, and the best model accurately predicted the LiDAR height using MODIS BRFs data (RMSE=1.2 m, R2= 0.67). This model was applied to the whole study area and finally the canopy height map of the study area was generated.","Title: Studies on methods for quality assessment of crop spectral data\nYear: 2004\n\nAbstract: In the process of measurement, a number of factors will affect the quality of data. Therefore, data must be verified and assessed before their applications. This paper discussed some methods for quality assessment of crop spectral data, which include methods of analysis of spectral characteristics, statistical test and spectral simulation. The method of spectral analysis compares measured spectra with the reference spectrum, and analyzes the location of wave crest, wave trough and the shape, intensity of spectral reflectance curves. The method of statistical test consists of shape similarity test and intensity test. The shape similarity test analyzes the correlation between measured spectral data and the reference spectral datum over the special wavelength range and assesses quality of the measured data by the correlation coefficients. The intensity test calculates the mean value and standard deviation of spectral data, and forms a spectral zone around the mean value. We consider it as the abnormal one if one spectral curve goes beyond the spectrum zone. The method of spectral simulation mainly compares measured spectra with simulated spectra by combined PROSPECT-SAIL model. Results show these methods of quality assessment are feasible","Title: Land Surface Parameters Retrieval Using Time Series Remotely Sensed Observations\nYear: 2007\n\nAbstract: Leaf area index (LAI) is an important parameter for estimating growth status of crops. An important method for retrieving LAI from remotely sensed observations is by the canopy reflectance model inversion. But many model inversion methods didn't take into account the relationship between estimated LAIs in different crop growth stages. In this research, we consider the crop growth model which describe how LAI change with crop growth stages. The main method for this research is assimilating multiple crop's canopy reflectance observed in different growth stages into the cost function for LAI retrieval. Data assimilation algorithm we used in this study is the variation algorithm. The model inversion results have showed that time series observations of canopy reflectance can decrease uncertainty of estimated LAI in model inversion.","Title: Estimating leaf area index by fusing MODIS and MISR data]\nYear: 2006\n\nAbstract: Moderate-resolution imaging spectrometer (MODIS) and multi-angle imaging spectroradiometer (MISR) are two important sensors on TERRA satellite. The authors can have more spectral and multi-angular observations on the land surface objects by combining these two datasets. In the present paper, both MODIS and MISR observations were combined to estimate leaf area index (LAI) of land surface. The adjoining model and trust-region optimal algorithm were introduced into the framework of physical model inversion to speed up the running of the model inversion algorithm. And the algorithm allows the prior knowledge on the retrieved parameters to be input into the inversion procedure. The uncertainty and sensitivity matrix (USM) based analysis is helpful for selecting the observed data subset with more information and less noise to retrieve LAI. The measured LAI in situ and estimated LAI from ETM data were scaling-up to MODIS/MISR LAI product scale, and were taken as the ground truth to evaluate the new approach. The result suggests that combining two sensors datasets can improve the accuracy of LAI estimation, and the developed inversion method in this paper can be applied to the large area remote sensed image data effectively.","Title: An Improved Algorithm to Produce Spatio-Temporally Continuous MODIS Albedo Product in China\nYear: 2008\n\nAbstract: Surface albedo is one of the key radiation parameters required for modeling of the Earth's energy budget, and many ecological and climate models usually require high quality consistent surface albedo as inputs and validation sources. The Moderate Resolution Imaging Spectroradiometer (MODIS) has been providing surface albedo products periodically. However, due to influence of weather, sensors and algorithms, MODIS albedo products often have many gaps and low quality pixels. This paper proposed an improved spatio-temporal smoothing algorithm utilizing multilevel procedure that combines spatial interpolation and tempora smoothing to get better albedo products based on multiyear observations and high quality neighboring pixels. Compared with field measurements, the improved albedo products in China based on MOD43B3 show better correlation with the measured surface albedo with the overall root mean squared errors around 0.0767. The generated albedo products may be applied in land surface models.","Title: Uncertain data mining from spectra library under Bayesian network model\nYear: 2004\n\nAbstract: Uncertainty is an inherent property of Remotely Sensed data. Under the architecture of Bayesian network, which can integrate the quantitative and qualitative knowledge into a comprehensive probabilistic knowledge representation and inference environment, this paper presents a model for data mining from spectra library. Using the filed measured data to drive the model, we obtain the crop structure variables such as Leaf Area Index (LAI) information, e.g. its probability distribution, which can be looked as the priori knowledge of the parameter during the process of inversion.","Title: Uncertainty Analysis For Ndvi Using The Physical Models\nYear: 2004\n\nAbstract: NDVI is the most widely applied vegetation index, it can indicate the information of growth status, LAI, et al. However, NDVI is also affected by the atmosphere conditions, soil background, view conditions and so on. In the Paper, we analyses the effects of chlorophyll, surface soil moisture, the ratio of sky light, view zenith and sun zenith on NDVI under different LAI using the leaf radiative transfer model PROSPECT and canopy reflectance model SAIL., and find the sensitive factors and ranges.","Title: Development of the Adjoint Model of a Canopy Radiative Transfer Model for Sensitivity Study and Inversion of Leaf Area Index\nYear: 2008\n\nAbstract: Many canopy reflectance models have been developed in the last decades and used for estimating land surface biogeophysical variables, such as leaf area index (LAI), from satellite observations through optimization procedures. In most studies, the derivative information of the canopy reflectance model has not been used effectively, which limits this approach for regional and global applications. Th...","Title: A new algorithm on delineation of management zone\nYear: 2005\n\nAbstract: The delineation of management zones is an economical and effective measure for the variable-rate application in precision agriculture. The methods of empirical and unsupervised classification have been used by many researchers in the delineation of management zones, but these methods are only built upon the information of attributes in every spatial cell, and the spatial relationships and their spatial interaction between cells are not considered. AS a result, there are many isolated cells or patches in the zoned map, this is not advantageous for the operation of the variable-rate application. Based on the traditional k-means cluster (K-M) and the spatial autocorrelation, a new method, spatial contiguous k-means clustering algorithm (SC-KM), was developed in this study. According to the spatial variability of wheat growth under within-field level extracted from OMIS image of the key growth stage, management zones were delineated by using K-M and SC-KM methods. Two evaluation indices were employed to evaluate the zoned results of the above mentioned two methods .The results showed that the sum of the weighted variance of the corresponding within-zones based on the two methods appeared no significant difference, and that the SC-KM method could remove lots of isolated cells or patches and improved the continuity of the corresponding management zone map, compared with the K-M method. The zoned result based on the SC-KM method can be used as the variable management unit for precision agriculture and can be used to advise the sampling of subsequent soil or crop.","Title: Studies on urban areas extraction from landsat TM images\nYear: 2005\n\nAbstract: In this paper, extracting urban areas from Landsat TM images is studied. We proposed a new method for urban and rural residential areas extraction. A classification example based on barren index(BI) is given in this article. We classified the image with several methods and compared the classification results. The result indicates this proposed method based on BI has obvious advantages over conventional multi-band spectral data classification. Classification map created by this method suffers less from a lack of spatial coherency and has a high classification accuracy. © 2005 IEEE.","Title: Validation of BRF data based on computer simulation model.\nYear: 2005\n\nAbstract: At present, modeling bi-direction reflectance of vegetation canopy scene, produced by computer simulation and a radiosity-graphics combined method (RGM), has already made preliminary progress. In order to qualify the simulated data, in this paper, taking winter wheat as an example, besides comparing computer simulated data with measured data, we also use anther method: regarding simulated data as the prior-data and condition data of SAIL model to inverse the structure parameters of vegetation canopy, such as LAI, ALA and component spectrum, which were the input parameters of computer simulation. Next, comparing these SAIL modeled data with the input data of computer simulation. Thus we can get the precision of LAI, and validate the reliability of BRF data based on computer simulation. On the other hand, evaluating the quality of algorithms and models used by computer simulation. Some conclusions are drawn from the investigation:(1) LAI is the important structure parameter for vegetation canopy scene, and we can control the whole scene and Its radiation regime only using LAI;(2)BRF data based on computer simulation model is reliable and its precision can meet the actual demands. So these BRF data can be considered as measured data to carry on research under certain conditions. ©2005 IEEE.","Title: Leaf area index estimation from MODIS data using the ensemble Kalman smoother method\nYear: 2010\n\nAbstract: The new data assimilation algorithm is developed to estimate LAI from time-series MODIS reflectance data (MOD09A1). The canopy radiative transfer model (ACRM) is coupled with an empirical LAI dynamic model, and the ensemble Kalman smoother (EnKS) is used to estimate the parameters of the coupled model from MOD09A1 data. The preliminary analysis using MODIS surface reflectance data at some AmeriFlux network sites was performed to validate this method. The results show that the algorithm is helpful to produce the temporally continuous LAI estimation of cropland efficiently. By comparing with the field measured LAI, the retrieved LAI has been significantly improved and shown more smooth in time series than the MODIS LAI product.","Title: Use of General Regression Neural Networks for Generating the GLASS Leaf Area Index Product From Time-Series MODIS Surface Reflectance\nYear: 2014\n\nAbstract: Leaf area index (LAI) products at regional and global scales are being routinely generated from individual instrument data acquired at a specific time. As a result of cloud contamination and other factors, these LAI products are spatially and temporally discontinuous and are also inaccurate for some vegetation types in many areas. A better strategy is to use multi-temporal data. In this paper, a method was developed to estimate LAI from time-series remote sensing data using general regression neural networks (GRNNs). A database was generated from Moderate-Resolution Imaging Spectroradiometer (MODIS) and CYCLOPES LAI products as well as MODIS reflectance products of the BELMANIP sites during the period from 2001-2003. The effective CYCLOPES LAI was first converted to true LAI, which was then combined with the MODIS LAI according to their uncertainties determined from the ground-measured true LAI. The MODIS reflectance was reprocessed to remove remaining effects. GRNNs were then trained over the fused LAI and reprocessed MODIS reflectance for each biome type to retrieve LAI from time-series remote sensing data. The reprocessed MODIS reflectance data from an entire year were inputted into the GRNNs to estimate the 1-year LAI profiles. Extensive validations for all biome types were carried out, and it was demonstrated that the method is able to estimate temporally continuous LAI profiles with much improved accuracy compared with that of the current MODIS and CYCLOPES LAI products. This new method is being used to produce the Global Land Surface Satellite LAI products in China.","Title: Validation Of Scale Effect Based On Computer Simulation Model\nYear: 2004\n\nAbstract: With the developing of satellite technology, more and more sensors, based on various resolutions and functions, are launched to the sky to perform their missions. Enormous data are sent back to the earth stations. In deriving surface parameters using these remotely sensed data, the transportability of algorithms from one resolution to another often cause the scale effect because of the surface heterogeneity on the earth which can induce the change of reflectance.The problem, that the change of reflectance data affected by discontinuity as part of surface heterogeneity impacts the retrieval of vegetation leaf area index (LAI), is addressed in this paper. Two cases, inducing the scaling issue in deriving surface parameters of interest, are considered here. One is the discontinuity between contrasting cover types within a mixed scene, the other is the non-linear relationship of NDVI and LAI. Therefore, it is necessary to apply the correction based on NDVI-LAI relationships to modify scaling problem.In the processing, considering the field of wheat, firstly a series of 3D scenes with wheat and soil mixed are made based on the field measurement; secondly, computer simulation model--the method of radiosity, which can calculate the balance of light energy in the simulated scenes, is used to model BRF(Bi-directional Reflectance Factor) of these scenes. If the NDVI-LAI relationship from homogeneous scenes can be taken as standard, the relationship from heterogeneous scenes will be modified according to contextural parameter. Some conclusions are drawn from the investigation: (1) different distributional contextures of vegetation even with the same LAI affect the reflectance heavily; (2) we compare the reflectance simulated by the method of radiosity with the mean reflectance calculated using the area-weighted linear relationship of reflectance from components, and find that the accuracy of the mean reflectance can be accepted so that the linear equation to calculate the reflectance of mixed pixels is reasonable to relate images with high and low resolution; (3) using contextural parameter for quantifying the scale effect can get promising results.","Title: A data-based mechanistic assimilation method to estimate time series LAI\nYear: 2013\n\nAbstract: In recent years, time series remote sensing data products have been assimilated into the coupled crop growth model and the radiative transfer model to improve the time series LAI estimation. However, due to the large number of input parameters to the crop growth model, the applications of the crop growth models for regional use is restricted. This paper proposed a data-based mechanistic assimilation method for estimation of the time series LAI from Moderate Resolution Imaging Spectroradiometer (MODIS) data. By coupling a revised universal data-based mechanistic model (LAI_UDBM) with a vegetation canopy radiative transfer model (PROSAIL), The proposed method applies the Ensemble Kalman Filter (ENKF) method to improve the estimation accuracy. Results indicate that the time series LAI estimated by this approach is superior to the MODIS LAI. Furthermore, because the model does not require the historical observation of every pixel, it is applicable over a wider range of uses.","Title: An Angular Index to Indicate Surface Heterogeneous Behaviors from MODIS\nYear: 2008\n\nAbstract: An anisotropic flat index (AFX) is among the operational BRDF and albedo products offered in both the V004 and V005 reprocessed versions. We examine this BRDF shape indicator with 20 ground multiangular data sets as well as MODIS satellite samples, and find that the AFX routinely captures the BRDF shape. An AFX < 1.0 indicates a dome shaped anisotropic pattern with prominent backscatter peak reflectances, and strong retro solar view angle (hotspot) maximum reflectances; an AFX = 1.0 approximately indicates a Lambertian surface; and an AFX > 1.0 corresponds to a bowl shaped anisotropy pattern. For green vegetation, the BRDF shape is related to canopy architecture. Therefore, the behavior of the AFX provides an opportunity to infer canopy structure of the surface cover that produces the anisotropic effect.","Title: Monitoring of wheat yellow rust with dynamic hyperspectral data\nYear: 2004\n\nAbstract: The objective in this study was to develop proper vegetation indices for prediction of soil irrigation demanding under vegetation covering conditions. The traditional method for the winter wheat yellow rust field survey is time consuming. It was discussed of the selection method of characteristic spectral bands and the establishing of inversion model to monitor winter wheat yellow rust using hyperspectral data in this study. The correlation coefficients between selected vegetation index and disease incidence (DI) at infected stages. Inversion models between DI and vegetation index such as normalized difference vegetation index (NDVI), ratio vegetation index (RVI), transformed vegetation index (TVI) were used to monitor yellow rust. The multi-temporal hyperspectral airborne images were acquired from winter booting stage to milking stage, and the yellow rust disease of winter wheat was analyzed using hyperspectral images. Compared with healthy wheat, spectral reflectance of disease wheat was higher in 560-670 nm bands but lower in near infrared bands and the absorption depth of chlorophyll in red band and reflectance peak in green band are relatively reduced. A novel spectral index for yellow rust indices was presented, and the degree and area of yellow rust disease were successfully remotely sensed from the multi-temporal hyperspectral data based on spectral index","Title: Comparison of three indirect field measuring methods for forest canopy leaf area index estimation\nYear: 2009\n\nAbstract: The Effective Plant Area Index (PAIe) of forest canopy is an important parameter in the canopy reflectance modeling and validation. PAIe can be transformed to leaf area index (LAI) with clumping index. But it is still very difficult to obtain its ground truth value by in situ measurement. In this study, we measured PAIe of 3 typical wood land sites in China by means of three indirect optical techniques: plant canopy analyzer LAI-2000, TRAC, and Digital Fisheye Camera. The 5 measured stands include Qinghai spruce, peach, poplar, willow and silver chain. In this paper, the forest canopy PAIe measured by those three instruments is compared firstly. Then our new approach is how to use the three measured data to get the better PAIe estimation with less overall error. The method of minimizing overall error is adopted to produce PAIe of the sample plots in our study sites, which has less overall error comparing with the PAIe measured by each individual instrument. This approach is also validated by using computer simulated wide-angle viewing pictures when true LAI/PAIe values are given.","Title: A Stepwise Refining Algorithm of Temperature and Emissivity Separation for Hyperspectral Thermal Infrared Data\nYear: 2010\n\nAbstract: Land surface temperature (LST) and land surface emissivity (LSE) are two key parameters in numerous environmental studies. In this paper, a stepwise refining temperature and emissivity separation (SRTES) algorithm is proposed based on the analysis of the relationship between surface self-emission and atmospheric downward spectral radiance in a narrow spectral region. The SRTES algorithm utilizes t...","Title: A method of upscaling ground measurements of Leaf Area Index based on Taylor Series expansion Model\nYear: 2012\n\nAbstract: The ground measurements of Leaf Area Index (LAI) are usually used to validate the LAI estimated using remote sensing observations. The main problem encountered in the validation is the scale mismatch between the sampling area of ground measurements and coarse-resolution image pixel, especially when those sampling area are not ideal homogenous. This study introduced a new approach of upscaling ground measurements to the coarse-resolution scale for the validation of LAI estimations. This upscaling method was based on the Taylor Series expansion Model (TSM). The high-resolution images were used to provide auxiliary information at the sub-pixel scale of coarse-resolution image pixel. The possible error associated with this method is derived from the neglection of the third- and higher-order TSM terms and the uncertainty of the empirical model. The upscaled ground measurements with upscaling error smaller than half of eigenaccuracy could be used for validation of LAI estimations with coarse resolution.","Title: Use of an ensemble Kalman filter for real-time inversion of leaf area index from MODIS time series data\nYear: 2009\n\nAbstract: It is an urgent need for natural disaster monitoring to generate biophysical variables data with high accuracy timely from remotely sensed data. A real-time inversion method to estimate leaf area index (LAI) using MODIS time series reflectance data (MOD09A1) is developed in this paper. A seasonal autoregressive integrated moving average (SARIMA) model is used to derive LAI climatology. A dynamic model is then constructed based on the climatology from the SARIMA model to evolve LAI in time, and used to provide the short-range forecast of LAI. Predictions from the model are used with the ensemble Kalman filter (EnKF) techniques to recursively update biophysical variables as new observations arrive. The validation results show that the real-time inversion method is able to produce a relatively smooth LAI product efficiently, and the accuracy is significantly improved over the MODIS LAI product.","Title: A Simple Data Assimilation Method for Improving Estimation of MODIS LAI Time-series Data Products Based on the 2-Dimensional LMS Adaptive Filter\nYear: 2006\n\nAbstract: Leaf area index (LAI) is an important parameter for describing vegetation canopy structure in the terrestrial ecosystem on the global, continental and regional scales. In this paper, a simple data assimilation method for improving estimation of MODIS LAI time-series data products based on a new 2-D LMS (two-dimensional least mean square) adaptive filter was proposed. Firstly, The new 2-D LMS adaptive filter algorithm is introduced and analyzed. Secondly, A simple data assimilation method for improving estimation of MODIS LAI time-series data products based on the new 2-D LMS adaptive filter and quality control data of MODIS LAI is proposed. Finally, the experiments are performed based on the simple data assimilation method using MODIS LAI data products from 2000 to 2005 of southwestern China.","Title: Crop Leaf Area Index Observations With a Wireless Sensor Network and Its Potential for Validating Remote Sensing Products\nYear: 2014\n\nAbstract: The collection of ground measurements for validating remotely sensed crop leaf area index (LAI) is labor and time intensive. This paper presents an automatic measuring system that was designed based on a wireless sensor network (WSN). The corn LAI was continuously observed from June 25 to August 24, 2012. Approximately, 42 in situ WSN measurement nodes were used in a 4 ×4 km2 area in the Heihe watershed of northwest China. The data were analyzed in three ways: 1) a comparison with LAI-2000, 2) a daily and 5-day aggregated time series analysis, and 3) a comparison with a Moderate Resolution Imaging Spectroradiometer (MODIS) LAI using both a ground LAINet LAI and a scaled-up LAI through inversion of Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) data. The preliminary results indicated that the measured LAI values from the LAINet were correlated with the values derived from LAI-2000 (R2 from 0.27 to 0.96 with an average of 0.42). When compared with the daily crop LAI growth trajectory, the performance of the measurement system was improved by using the data that were aggregated over a 5-day window. When compared with MODIS LAI, we found that the spatial aggregation values of the ground LAINet observations and the scaled-up ASTER LAI were identical or similar to the MODIS LAI values over time. With its low-cost and low-energy consumption, the proposed WSN observation system is a promising method for collecting ground crop LAI in flexible time and space for validating the remote sensing land products.","Title: Uncertainty of remote sensing model inversion and a synthetical inverse scenario\nYear: 2002\n\nAbstract: The sources of the inverse error of remote sensing physical models are analyzed and divided into two groups. From the point of view of controlling these errors, a synthetic inverse scenario is put forward. A case study using simulated data shows that this scenario is better than ordinary methods in robustness and global convergency.","Title: Approach and validation on land surface albedo retrieval using multiangular remote sensing observations\nYear: 2002\n\nAbstract: The main problem in the validation is that the field-measured albedo is different in scale from the albedo estimated using remote sensing data. The albedo-meter based field measurement is over a small area. On the contrary, the spatial resolution of the MODIS albedo production is about 1 km. Another problem is the different wavebands or albedo-meter and MODIS sensor. As a solution, we suggest to use the field multiangular measurements data that is captured in a small field of view (FOV) to retrieve the albedo by Ambrals model inversion. As a result, the retrieved albedo is comparable with that measured by albedo-meter since they have the same scale. At the same time, the effect of wavebands difference is also corrected. In the second step, we extend this method to the airborne MARS observations of the same target. Scaling-up can be considered based on the two inverted albedos. The retrieved albedo from airborne data can be validated using field measurement too. Finally, the airborne retrieved albedo can be used to validate the MODIS albedo production. In this framework, the field measured data sets come from a large satellite-airborne-ground synchronous experiment that was taken in Shunyi, which is in the north of Beijing, in April of 2001.","Title: A priori knowledge in the inversion of linear kernel-driven BRDF models\nYear: 2002\n\nAbstract: A priori knowledge can come from field measurements of bidirectional reflectance factors for various surface cover types. How to express and use this kind of knowledge is very important currently. 73 sets of field observations are used to explore the possible expression of a priori knowledge in linear kernel-driven BRDF models in this paper.","Title: BRDF modeling and inversion of structure parameters for sparse vegetation canopy\nYear: 2002\n\nAbstract: Multi-angular remote sensing became a hot topic after the non-Lambert characteristic of the Earth's surface had been accepted popularly. A large amount of multi-angular remote sensing data has been obtained with the launch of multi-angle remote sensing sensors. Therefore, modeling of the bi-directional reflectance distribution function (BRDF) for the Earth objects is one of the main subjects at present. A large satellite-airborne-ground synchronous remote sensing experiment was carried out during March 29 to May 10, 2001 at Shunyi, China. The main observation target in this experiment is focused on winter wheat. To describe the BRDF of winter wheat in its early growing stages, we propose a geometric-optical model that is suitable for sparse vegetation, and then try to retrieve the structure parameters based on this model using the field measurements. The purport of the model and its inversion is to inspect the ravages of drought on the wheat just as it is turning green. The winter wheat in our measurement field is sparse and disperses without clear row structures in its turning-green stage. Typical row structure based models and uniform structure based models are not suitable. Our model is developed based on the Li-Strahler geometrical-optical model proposed in 1985. Each cluster of wheat is treated as a hemi-ellipsoid in this model. All of the leaves in the cluster are assumed to cover the hemi-ellipsoid randomly. Leaf area index and leaf angle distribution are two important parameters that are related to the surface area of the hemi-ellipsoid and the leaf distribution on this surface respectively. Leaf angle distribution is also related to the shape of the hemi-ellipsoid. Due to the large uncertainty of the number of hemi-ellipsoids in a unit area, we retrieve this parameter based on our model using the most sensitive samples first, and then treat it as a priori knowledge in the later inversion. The next stage is studying how to use multi-angle remote sensing data to invert vegetation structure parameters.","Title: The BRDF model and analysis of hotspot effect of row crops\nYear: 2002\n\nAbstract: According to the Li-Strahler model, a BRDF model of row structure with gap, in which three components and six paths are taken into account, is established through analysis of the process of radiation transfer. The model is verified by the data obtained in the Satellite-Airborne-Ground Synchronous Quantitative Remote Sensing Experiment implemented from March 29 to May 10 in 2001, in Shunyi, Beijing, China. As is shown, the model can demonstrate effectively the reflection of crops with row structure.","Title: A thermal bidirectional gap model for row crop canopies\nYear: 2002\n\nAbstract: We propose a thermal bidirectional gap model to describe the thermal directional emission from row crop canopies. An important concept of overlap index is used in this model to express the correlation between the gaps in the Sun and view directions. Detailed directional thermal emissions, row structure, LAI, component temperatures were measured in the experiment taken in Shunyi China, 2001. These data are used to validate our model. As an illustration, we compared our bidirectional gap model with the model that doesn't consider gaps (Kimes model) and the model only consider gaps in view direction. It is found that our model gives out the closest results to the field measurements.","Title: Local statistic-based fusion of MIVIS VNIR and simulated TIR images\nYear: 2002\n\nAbstract: Local statistic-based fusion algorithms are discussed, which can be applied to fuse high-resolution VNIR images and a single low-resolution TIR image. These algorithms are based the experiments that structural information of observed objects in visible and near-infrared spectral range (VNIR) is essentially correlated with the environmental information (especially moisture information) in thermal infrared spectral range (TIR). The local is performed at three scales. This algorithm can be useful method to merge the TIR image and VNIR images.","Title: Design and implementation of knowledge base for quantitative remote sensing\nYear: 2002\n\nAbstract: The remotely sensed images can be understood and analyzed better through comparing the remote sensing spectrum and the spectrum with known land surface structure and physical chemistry parameters. It is unavoidable to compute land surface spectrum based on prior knowledge and remote sensing physical models when we cannot obtain the measured spectrum on suitable time and pixel size. The remote sensing knowledge base integrates data, image, and physical models for quantitative remote sensing. Here in our remote sensing spectral knowledge base, the digital elevation model, land cover and land cover maps and soil map are restored in the spatial database. The climatic changes and spatial patterns of vegetation are restored in the expert system. And component spectrum of vegetation, soil, water, snow, minerals, man-made object are measured and also stored in the database. It is apparent that they themselves have data systems and the systems usually are different with input and output parameter systems of remote sensing physical models. In order to solve the discrepancies, metadata of data and model are put forward. About design of the knowledge base, defining and organizing metadata is key task. Accordingly to data, image and model in the knowledge base, the metadata also consists of metadata about data, metadata about image, and metadata about model. Metadata describes formation, quality and meaning of data, image and model. Data exchanges between database, image base and model base are found on the metadata, and is coordinated by an expert system based on rule, so data extraction and re-organizing will obtain flexible as large as possible. The data-engine extracts data from databases and transfers the data between database and model base, and the model-agent selects suitable models to extend the structure and physical chemistry parameters, and extract land surface facts, finally compute the land surface spectrum on multi-temporal & spatial scales.","Title: Modeling the albedo of mixed vegetation canopy and snow\nYear: 2002\n\nAbstract: Predictions of climate change typically use a GCM linked to a land surface model. Land surface models, e.g. Biosphere-Atmosphere Transfer Scheme (BATS), estimate the albedo of trees over snow roughly with the parameters of roughness length, z0, and snow depth, d. Based on their work, we further consider the difference in directional-to-hemisphere albedo for different solar zenith angle (SZA), and leaf area index (LAI) dependence. In order to keep the basic feature of the BATS model and to add these two new features, we simplified the geometric optical and radiative transfer (GORT) hybrid model of Li, et al. [1995] to reach this purpose. This model can be rather simple to retrieve the albedo of remote sensing pixel. It can be a strong tool to understand the climate system.","Title: Information content of multi-angular remote sensing data\nYear: 2002\n\nAbstract: In this paper, we take the kernel-driven model as an example, focus on the information contents definition and calculation of multi-angular remote sensing (MARS) data. We study four methods to measure the information content of MARS data: Fisher statistic, information entropy, determinant and sum of the diagonal elements of the information matrix, how to use the Fisher statistic theory and information entropy to measure the information contents of MARS data, to calculate the information contents of the dataset on the three unknowns for different subset of the data. The analyses show that information entropy is a good tool for measuring information content of MARS data.","Title: Analyses Of The Relationship Between Atmospheric Temperature Structure And Eofs\nYear: 2003\n\nAbstract: EOF (Empirical Orthogonal Function) technique is usually used in thermal remote sensing in order to reduce the number of the parameters to be inversed. Few researchers put emphases on the physical meaning of the eigenvectors. Our study shows that different eigenvector corresponds with different atmospheric layer. It is necessary to study the physical meaning of the eigenvectors in remote sensing inversion, especially when we put emphases on one or some original unknown parameter(s), which is a common need in remote sensing inversion. First, one EOF choice scheme is proposed in our paper. It not only satisfies the need of whole explained variance but also considers the partial variance related with the parameter we are interested in. The inversion result shows that the scheme is useable to the special unknown parameters. At last, the physical meanings of EOFs have been discussed based on the large sample.","Title: Atmospheric correction for AMTIS single-channel multi-angular thermal-infrared imagery\nYear: 2003\n\nAbstract: This paper presents the atmospheric correction algorithm for the TIR band of Airborne Multi-angle TIR/VNIR Imaging System (AMTIS) assumed that no atmospheric profile is available. Under the assumption that the surface emissivity is isotropic, two atmospheric parameters are needed to remove the atmospheric effect: the water vapor content (W) and the effective mean atmosphere temperature (T a). T a can be estimated from the muti-angular observations of the pixel with \"minimum standard deviation\" of brightness temperatures. After T a is known, W can be retrieved from the pixels with multi-angular observations under the assumption of isotropic emissivity and horizontal uniform atmosphere. Then the atmospheric effect can be removed after the two atmospheric parameters are known. Through the sensitivity analysis of the algorithm to emissivity and transmittance, it can be found that W is very sensitive to the error of emissivity. However, it can also be estimated using the pixel with known surface temperature and emissivity measured synchronously.","Title: Leaf Area Index Inversion Using Multiangular And Multispectral Data Sets\nYear: 2003\n\nAbstract: Leaf area index (LAI) is an important parameter for describing vegetation canopy structure in the terrestrial ecosystem. LAI is closely related to plant transpiration, sunlight intercept, photosynthesis and Net Primary Productivity. Multiangular remote sensing is capable of providing more three-dimension information of vegetation, and it is powerful in solving the problem of the same object with different spectrum or vice versa. As a result, multiangular remote sensing and Bidirectional Reflectance Distribution Function (BRDF) model based inversion may be more suitable for Leaf Area index (LAI) retrieval over row crop canopies. However, it's still difficult to get LAI without enough a priori knowledge due to the underdetermined problems in inversion. We use the multispectral information to get the a priori estimation of LAI, and then perform BRDF model inversion. Different from the general one channel based BRDF model inversion methods, our new methods use the muiltiangular and multispectral data sets together to increase the available information in inversion, i.e., it is a synthetic method. From the inversion results we found that the new synthetic method is more effective in LAI inversion.","Title: An Iterative Temperature Inversion Method For Nonisothermal Land Surfaces\nYear: 2003\n\nAbstract: We propose an iterative multistage inversion (IMI) algorithm to retrieve the land surface component temperatures for nonisothermal vegetation canopy. Our algorithm is based on a thermal emission model that can simulate the directional effects from the nonisothermal surfaces. Our IMI algorithm just inverts the most uncertain and most sensitive parameters at each step using the most sensitive observation samples, and then adjusts the initial values based on the retrieval results. This inversion process is repeated until convergence condition is satisfied. Compared with the inversion method that try to invert all of the parameters at the same time, the IMI algorithm tends to give more accurate mean values for the parameters and is more stable when the noise level is relative low.","Title: Retrieval Of Aerosol Optical Depth And Single Scattering Albedo From Amtis Imagery\nYear: 2003\n\nAbstract: Airborne Multi-angle TIR/VNIR Imaging System (AMTIS) that sample the surface at a number of view angles offer the potential of retrieval of atmospheric aerosol properties, land surface bidirectional reflectance etc. This paper presents the retrieval algorithm of aerosol optical depth and single scattering albedo from visual and near-infrared bands of AMTIS based on a simplified path radiance model. Atmospheric parameters such as molecule scattering and absorption are calculated using MODTRAN4. Under the assumption that the aerosol optical depth above the sensor is not affected by the surface, the aerosol optical depth above the sensor (4.2Km) is also calculated using MODTRAN4. The path radiance is divided into two components: the singly scattered radiance and multiple-scattering radiance. The AMTIS images acquired on Apr. 11, 2001 in the Shunyi experiment are used in the retrieval. The algorithm performs best over the dark surfaces, such as water. The retrieved aerosol optical depth is close to the result from the synchronous Sun photometer data with an error about 0.05similar to0.1. Retrieved single scattering albedo is very close to that of the continental aerosol model of 6S.","Title: The maximum entropy algorithm for the determination of the Tikhonov regularization parameter in quantitative remote sensing inversion\nYear: 2003\n\nAbstract: Remote sensing inversion problem is always ill-posed. However, regularization aims at turning the ill-posed problems into certainty. In this paper, taking the linear kernel-driven model as an example, we put forward the maximum entropy algorithm based on information theory to determine the Tikhonov regularization parameter. Then, analyse and compare it with other mature methods. Result shows that the maximum entropy algorithm has advantages when the variance of the observations' noise is small or uncertainty of the prior knowledge is not too large.","Title: Atmospheric correction for AMTIS VIS/NIR bands imagery based on BRDF loop and MODTRAN4\nYear: 2003\n\nAbstract: This paper describes the atmospheric correction algorithm for the Airborne Multi-angle TIR/VNIR Imaging System (AMTIS) in VIS/NIR bands. The method is named as a BRDF loop based algorithm. Under the assumption of that the ground cover is non-Lambertian, MODTRAN4 is used to calculate the atmosphere parameters, and the parameters used to decouple the multi-bouncing effect such as direct-hemisphere reflectance and hemisphere-direct reflectance are estimated in the loop correction process. The BRDF model used to calculate albedo is the kernel-driven model. To accelerate the atmospheric correction, all the atmospheric parameters used in this algorithm are pre-computed used MODTRAN4.1 and saved in the look-up table. A prior knowledge is used in the inversion of kernel-driven model when the multi-angle sampling is not enough. The atmospheric correction result is validated using the synchronous ground measurements. From the comparison with the general Lambert assumption based method, it is found that our BRDF loop based method can partly remove the atmospheric smoothing effect.","Title: Study on energy balance over different surfaces\nYear: 2003\n\nAbstract: Eddy covariance and Bowen ratio measurements were carried out over different surfaces, and used to characterize the daily variation of energy fluxes and energy balance under different weather condition. These will be used to identify the phenomena to be addressed in future modeling works. Results show that (1) The diurnal variation characteristics of the fluxes were different over different surfaces, especially the latent heat flux, (2) The energy imbalance persisted in different surfaces with an average about 20%; the energy balance closure was better in the afternoon than in the morning averagely, possibly suggesting the underestimation of storage terms, which are usually larger in the morning.","Title: Validation Of Modis Albedo Product By Using Field Measurements And Airborne Multi-Angular Remote Sensing Observations\nYear: 2003\n\nAbstract: dAlbedo is a key parameter in monitoring the energy exchanges between the solar radiations and the land,surfaces. The MODIS team generates the albedo products every 16 days. The products need to be validated by ground truths under different environmental conditions. In this study, we developed a 3-step validation procedure. The Ambrals (Algorithm for Modeling Bidirectional Reflectance Anisotropies of the Land Surface) model inversion was used to retrieve the albedo from the measured BRDF data over the winter wheat fields at the point/plot scale. And then, as our second step, the albedo values from the Airborne Multiangular Thermal-infrared Imaging System (AMTIS) over the same target area were estimated and validated using the ground point measurements. Finally, the retrieved albedo from airborne data were aggregated and compared with the MODIS albedo products. Our validation procedure has demonstrated a practical method to validate that albedo from spacebrone remotely sensed data (e.g., MODIS). The validation results show that the MODIS albedo products are reasonably good.","Title: The construction of J2EE-based Spectrum Knowledge Base System for Typical Object in China\nYear: 2003\n\nAbstract: The Spectrum Knowledge Base System (SKBS) for Typical Object in China, built up by taking advantage of J2EE technology, is capable of providing the functionalities in spectrum analysis, query and comparison. More importantly, the spectrum scale effect, especially the scale extension, can be achieved in SKBS, which is based on the model-driven theory with the support of the prior knowledge.","Title: Practice of quantitative remote sensing model library based on COM technique\nYear: 2003\n\nAbstract: With the development of remote sensing, new models are available continuously. In order to extend the practicability of the model library, the authors introduce component object model (COM) technique. COM is a software architecture that allows the components made by different software vendors to be combined into a variety of applications. Remote sensing model library is composed of three parts, common objects, model objects and accessorial objects. Common objects include input/output procedure, solar angle calculating procedure in bi-directional reflectance, and metadata about all the models. Model objects include the models contributing to quantitative remote sensing applications, which comprise system models, simulant models and application models. Accessorial objects include prior knowledge, measurement data and image data. In the article, the executable project is validated with an instance in the end. The spectrum of typical land surface observed in nadir viewing direction is simulated in pixel scale. In this process, crop model, PROSPECT model and SAIL model are used to calculate the spectrum character of the pixel. Crop model is used to simulate leaf area index, and PROSPECT model is to simulate reflectance and transmission of leaves. The final result is calculated with SAIL model. We simulated the spectrum of winter wheat in given growing season. In the work, each model and each common object are designed to be components. The model library based on COM technique adapts to the progress and is propitious to be expanded and modified.","Title: Using Path Analysis To Study Correlation And Causation In Remote Sensing Inversion\nYear: 2003\n\nAbstract: One problem in quantitative remote sensing inversion is the correlations between variables. Path analysis is a statistical technique that differentiates between correlation and causation, features multiple linear regressions, and generates path coefficients. In this paper, path analysis was applied to study the correlations and causations of two cases in remote sensing reversion. One is the retrieval of land surface temperature, and another is to explain the results of land surface moisture estimation. We found that path analysis can be used to study the direct effect and the indirect effects of a variable in remote sensing inversion, and gave a better explanation of the results of multiple linear regression analysis.","Title: Using the NDVI Contribution Ratio at Different Growth Stages to Estimate Winter Wheat Yield\nYear: 2003\n\nAbstract: This paper mainly proposed using multi-temporal spectral data with given weight to estimate yield using contribution ratios of different stages to improve yield estimation, then use stepwise regression to build models for yield estimation. The contribution ratio is calculated by principal component analysis respectively. Result show that this methodology reflects the crop growth status, physiological characters at different stages, and improves the accuracy obviously.","Title: An Approach On Lai Assimilation Between Field Measurement And Crop Model Simulation\nYear: 2003\n\nAbstract: LAI (Leaf Area Index) is an important parameter for plant growth status detecting. The traditional method to measure leaves' area in field is time and labor consuming. In some remote sensing applications, LAI might be needed more intensively such as daily and weekly. Crop simulation models can be effective tools for simulating LAI, crop and soil water statuses, crop growth and development parameters at the daily step.Ground LAI measurements for winter wheat were carried out in several fields of Shunyi county, Beijing, China at several days' interval during the crop growth season. The CERES-wheat model is run under local soil, weather and management conditions of a field site to simulate daily LAI values. The simulated LAI corresponded comparatively well with the measured ones at the early stage. The results suggested that the technique might be promising for estimating LAI, this make it possible to develop an approach to assimilate LAI of winter wheat between ground measurements and CERES-wheat simulation.","Title: Class-Based Kernels Selection For Albedo Inversion By Kernel-Driven Brdf Model\nYear: 2003\n\nAbstract: The kernels are always pre-determined in current kernel-driven model application, but it seems to have a bit disadvantages to the requirement of more accurate remote sensing because it used one kernel combination for all land cover types' inversion. In this paper, we used the 28 different multi-angular data sets, which represent major types of land cover, to find out the relations of different kernels' selection with land cover types firstly. The kernels combinations in the models we compared are volume kernels of Ross-Thick, Ross-Thin and geometric optical kernels of Li-Transit, Li-SparseR and Li-Dense. Then, and the airborne multi-angle TIR/VNIR image system (AMTIS) data set, which was got at Shunyi county of Beijing, China in April 2002, was used to inverse. The inversion results of pre-determined kernels selection and class-based kernels selection were compared, respectively.","Title: Correlation Analysis Between Hyperspectral Feature And Foliage Water Content In The Growth Period Of Winter Wheat\nYear: 2003\n\nAbstract: At XiaoTangShan Precision Agriculture Experiment Base, suburban of Beijing city, we obtained the hyperspectral data of wheat canopy by field measurement and synchronal relative foliage water content (RFWC) at lab, according to the different growth stage of wheat, in the spring of 2002. In this paper, we extracted spectral feature parameters firstly. Then, the correlation analysis between the spectral features parameters and RFWC was made. two spectral feature parameters, which have good relativity to foliage water content, to make linear regression models between RFWC and spectral feature parameter according to the growth stages of wheat.","Title: Monitoring the seasonal bare soil areas in Beijing using multi-temporal TM images\nYear: 2004\n\nAbstract: Recently, there were many strong sandstorms occurred in North China, which became a severely economical, social and environmental problem, especially for Beijing City. The bare soil is an important source of sandstorm, and the croplands naked in winter in 55 counties around Beijing City became the main source of the sandstorm. It is very important to monitor the seasonal bare soil areas using remote sensing data. The multitemporal TM images of Beijing area in May 16, 1997, April 7, 2003, May 25, 2003, October 24, 2003 and January 28, 2004 were selected. Firstly, the smoothing filter-based intensity modulation (SFIM) completed the image fusion. Secondly, the multistage classification approach was adopted. The multisource data, such as DEM, NDVI, bare soil index (BI), shadow index (SI), were integrated and applied in classification, and the seasonal bare soil areas, such as wasteland, cropland, were successfully extracted. Thirdly, the seasonal and inter-annual dynamic changes of the bare soil areas were also analyzed.","Title: A Framework for Consistent Estimation of Leaf Area Index, Fraction of Absorbed Photosynthetically Active Radiation, and Surface Albedo from MODIS Time-Series Data\nYear: 2015\n\nAbstract: Currently available land-surface parameter products are generated using parameter-specific algorithms from various satellite data and contain several inconsistencies. This paper developed a new data assimilation framework for consistent estimation of multiple land-surface parameters from time-series MODerate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. If the reflectance data showed snow-free areas, an ensemble Kalman filter (EnKF) technique was used to estimate leaf area index (LAI) for a two-layer canopy reflectance model (ACRM) by combining predictions from a phenology model and the MODIS surface reflectance data. The estimated LAI values were then input into the ACRM to calculate the surface albedo and the fraction of absorbed photosynthetically active radiation (FAPAR). For snow-covered areas, the surface albedo was calculated as the underlying vegetation canopy albedo plus the weighted distance between the underlying vegetation canopy albedo and the albedo over deep snow. The LAI/FAPAR and surface albedo values estimated using this framework were compared with MODIS collection 5 eight-day 1-km LAI/FAPAR products (MOD15A2) and 500-m surface albedo product (MCD43A3), and GEOV1 LAI/FAPAR products at 1/112° spatial resolution and a ten-day frequency, respectively, and validated by ground measurement data from several sites with different vegetation types. The results demonstrate that this new data assimilation framework can estimate temporally complete land-surface parameter profiles from MODIS time-series reflectance data even if some of the reflectance data are contaminated by residual cloud or are missing and that the retrieved LAI, FAPAR, and surface albedo values are physically consistent. The root mean square errors of the retrieved LAI, FAPAR, and surface albedo against ground measurements are 0.5791, 0.0453, and 0.0190, respectively.","Title: The exploring research of a geometric optical canopy reflectance model (GOMS) for retrieving leaf area index directly\nYear: 2014\n\nAbstract: Forest canopy leaf area index (LAI) is an important biological parameter and an evaluation index of the vegetation canopy. It is difficult to get LAI through direct inversion using Li-Strahler geometric-optical model (GOMS)[1,2]. In this paper, LAI is introduced into the GOMS model as an independent variable to substitute other canopy structure parameters. The verification results well demonstrated the accuracy of the modified GOMS model.","Title: Direct validation of MODIS spectral Abledo product with field measurement\nYear: 2014\n\nAbstract: Land surface albedo is a key input parameter required in the current general circulation models (GCMs). The accurate validation of albedo products is very important for use in various applications by the scientific community. The most common validation methods compare motely sensed albedo products directly with ground-based observed broadband albedo values without considering the band width inconsistency and the narrow-to-broad band transformation error of these products. Unlike previous validation approaches, we propose a spectral albedo direct validation method. By applying the novel instrument of multi-band albedometer, it is possible to obtain MODIS visible and near-infrared bands albedo measurements. The in-field measured data combined with a 16-day interval is compared directly with MODIS narrow band albedo products. The results indicate that the multi-band albedometer measurement and the MODIS narrow band white and black sky albedo has a good consistency. It is an efficient way to get rid of the errors induced by the band conversion and is a labor-saving technique of making possible time series measurements.","Title: Modeling MODIS NBAR time series of vegetated surfaces and its use in LAI recursive estimation\nYear: 2014\n\nAbstract: The inconsistent data quality of remote sensing observation, which is mainly caused by atmospheric conditions, presents problems in the application of these data. For the land cover types that cycle yearly, the variations in surface reflectance usually have temporal periodic characteristics. In this study, we modeled the temporal feature of Moderate-Resolution Imaging Spectroradiometer (MODIS) Nadir BRDF-adjusted reflectance (NBAR) time series data of the typical vegetated area using the season-trend statistical method. The fitting values of season-trend model were applied to the recursive estimation of leaf area index (LAI) time series based on nonlinear autoregressive exogenous (NARX) neural network. The results of MODIS NBAR modeling indicate that the season-trend method is effective to model the NBAR time series of the vegetation surface. The NARX neural network works well using the improved NBAR time series as input, and the estimated LAI time series is more continuous than the MODIS LAI.","Title: Quantitative remote sensing research on the vegetation 3-D visual simulation based on object oriented technique\nYear: 2003\n\nAbstract: In the field of remote sensing, it is important to understand interaction between light and vegetation. The interrelation of them has been addressed in many works, and many different radiant models of vegetation have been proposed, such as: geometrical optical models, turbid medium models, hybrid models and computer simulation models. With developing of quantitative remote sensing research, computer simulation models, for example, Monte Carlo simulation model and Radiosity show their importance in analyzing the experimental data. In order to continue calculating the reflectivity from the vegetation by using a computer simulation model, it is essential to build the 3D structure of the vegetation. Therefore, many 3D structure data and optical parameters about the real winter wheat were measured firstly, i.e. height of stem, positions and sizes of the leaves, distributions on the field of wheat. Because these data are numerous and discrete, it is very difficult to simulate the virtual scene with them directly. To cope with it, we arranged all data and parameters in several layers based on the object oriented technique. Moreover, in order to simplify and deduce the structural variables that will be applied to build the 3D visual winter wheat model, we analyzed experimental data statistically in the process of realistic structural model. Several geometric and logical relations about structural variables were developed subsequently, and some variables varying with season were summarized to get the simple regulation with the purpose of simulating growing process of the winter wheat. The extended Lindenmayer system (L-system) method is then used to simulate the virtual scene of winter wheat by giving a few structural variables simplified before. Once the simulation is correct, scattering and reflectance from the 3D structural scene can be calculated using the Monte Carlo simulation model or Radiosity and so on. Our results show that (a) our lighting simulation system efficiently provides the required information at the desired level of accuracy, and (b) the plant growth model is extremely well calibrated against real plants. Furthermore, the method and the relations developed in this paper can be used in other subjects, such as computer graphics.","Title: MLAOS: a multi-point linear array of optical sensors for coniferous foliage clumping index measurement.\nYear: 2014\n\nAbstract: The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8-10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy.","Title: Improving Space-Time Forest Canopy Lai Simulation By Fusing Forest Growth Model (3-Pg) With Remote Sensing Data\nYear: 2015\n\nAbstract: Leaf area index (LAI) is an important biophysical variable indicating forest growth. A major challenge is to improve the LAI estimates for large forest-covered areas. One way to obtain LAI value is using current LAI products. Current LAI products contain many uncertainties and need improvement. This paper aims to improve forest LAI estimates by combining satellite reflectance derived LAI with forest growth model (physiological principals predicting growth, 3-PG) estimates of LAI. 3-PG can give an accurate estimation of forest inter-annual growing trend, while remote sensing data can provide long time series observation of seasonal variations of forest phenology. We applied this method to Chinese fir forest in China, where the detailed data are available. The combined results were more accurate than either the satellite or the 3-PG estimates. We conclude that we can improve the space-time forest canopy LAI estimates by combining forest growth model with satellite imagery.","Title: Long-Time-Series Global Land Surface Satellite Leaf Area Index Product Derived From MODIS and AVHRR Surface Reflectance.\nYear: 2016\n\nAbstract: Leaf area index (LAI) is an important vegetation biophysical variable and has been widely used for crop growth monitoring and yield estimation, land-surface process simulation, and global change studies. Several LAI products currently exist, but most have limited temporal coverage. A long-term high-quality global LAI product is required for greatly expanded application of LAI data. In this paper, ...","Title: Bias Analysis In Validation Of Modis Lai Product: A Case Study In Cropland Of Huailai, Northern China\nYear: 2016\n\nAbstract: In the validation of MODIS LAI product, much attention has been paid to directly compare the product data and the reference values, few efforts have been made to analyze the bias of validation result comprehensively. In this paper, based on the evaluation of MODIS LAI product, we further divide the bias into three aspects: algorithm, reflectance data and clumping effect. Moreover, the individual influence on the total bias is quantified. The results of assessment indicate MODIS LAI product has an obvious underestimate, as much as 34.14% in this area compared with reference LAI. Individual influence on the total deviation of each bias is 57.50%, 28.33% and 14.17%, respectively.","Title: Multiscale Estimation of Leaf Area Index from Satellite Observations Based on an Ensemble Multiscale Filter.\nYear: 2016\n\nAbstract: Currently, multiple leaf area index (LAI) products retrieved from remote sensing data are widely used in crop growth monitoring, land-surface process simulation and studies of climate change. However, most LAI products are only retrieved from individual satellite observations, which may result in spatial-temporal discontinuities and low accuracy in these products. In this paper, a new method was developed to simultaneously retrieve multiscale LAI data from satellite observations with different spatial resolutions based on an ensemble multiscale filter (EnMsF). The LAI average values corresponding to the date of satellite observations were calculated from the multi-year Moderate Resolution Imaging Spectroradiometer (MODIS) LAI product and were used as a priori knowledge for LAI in order to construct an initial ensemble multiscale tree (EnMsT). Satellite observations obtained at different spatial resolutions were then applied to update the LAI values at each node of the EnMsT using a two-sweep filtering procedure. Next, the retrieved LAI values at the finest scale were used as a priori knowledge for LAI for the new round of construction and updating of the EnMsT, until the sum of the difference of LAI values at each node of the EnMsT between two adjacent updates is less than a given threshold. The method was tested using Thematic Mapper (TM) or Enhanced Thematic Mapper Plus (ETM+) surface reflectance data and MODIS surface reflectance data from five sites that have different vegetation types. The results demonstrate that the retrieved LAI values for each spatial resolution were in good agreement with the aggregated LAI reference map values for the corresponding spatial resolution. The retrieved LAI values at the coarsest scale provided better accuracy with the aggregated LAI reference map values (root mean square error (RMSE) = 0.45) compared with that obtained from the MODIS LAI values (RMSE = 1.30).","Title: Bayesian Method for Building Frequent Landsat-Like NDVI Datasets by Integrating MODIS and Landsat NDVI.\nYear: 2016\n\nAbstract: Studies related to vegetation dynamics in heterogeneous landscapes often require Normalized Difference Vegetation Index (NDVI) datasets with both high spatial resolution and frequent coverage, which cannot be satisfied by a single sensor due to technical limitations. In this study, we propose a new method called NDVI-Bayesian Spatiotemporal Fusion Model (NDVI-BSFM) for accurately and effectively building frequent high spatial resolution Landsat-like NDVI datasets by integrating Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat NDVI. Experimental comparisons with the results obtained using other popular methods (i.e., the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM), and the Flexible Spatiotemporal DAta Fusion (FSDAF) method) showed that our proposed method has the following advantages: (1) it can obtain more accurate estimates; (2) it can retain more spatial detail; (3) its prediction accuracy is less dependent on the quality of the MODIS NDVI on the specific prediction date; and (4) it produces smoother NDVI time series profiles. All of these advantages demonstrate the strengths and the robustness of the proposed NDVI-BSFM in providing reliable high spatial and temporal resolution NDVI datasets to support other land surface process studies.","Title: Comparison and Evaluation of Three Methods for Estimating Forest above Ground Biomass Using TM and GLAS Data.\nYear: 2017\n\nAbstract: Medium spatial resolution biomass is a crucial link from the plot to regional and global scales. Although remote-sensing data-based methods have become a primary approach in estimating forest above ground biomass (AGB), many difficulties remain in data resources and prediction approaches. Each kind of sensor type and prediction method has its own merits and limitations. To select the proper estimation algorithm and remote-sensing data source, several forest AGB models were developed using different remote-sensing data sources (Geoscience Laser Altimeter System (GLAS) data and Thematic Mapper (TM) data) and 108 field measurements. Three modeling methods (stepwise regression (SR), support vector regression (SVR) and random forest (RF)) were used to estimate forest AGB over the Daxing'anling Mountains in northeastern China. The results of models using different datasets and three approaches were compared. The random forest AGB model using Landsat5/TM as input data was shown the acceptable modeling accuracy (R-2 = 0.95 RMSE = 17.73 Mg/ha) and it was also shown to estimate AGB reliably by cross validation (R-2 = 0.71 RMSE = 39.60 Mg/ha). The results also indicated that adding GLAS data significantly improved AGB predictions for the SVR and SR AGB models. In the case of the RF AGB models, including GLAS data no longer led to significant improvement. Finally, a forest biomass map with spatial resolution of 30 m over the Daxing'anling Mountains was generated using the obtained optimal model.","Title: Extended Data-Based Mechanistic Method for Improving Leaf Area Index Time Series Estimation with Satellite Data.\nYear: 2017\n\nAbstract: Leaf area index (LAI) is one of the key parameters in crop growth monitoring and global change studies. Multiple LAI products have been generated from satellite observations, many of which suffer from data discontinuities due to persistent cloud contamination and retrieval algorithm inaccuracies. This study proposes an extended data-based mechanistic method (EDBM) for estimating LAI time series from Moderate Resolution Imaging Spectroradiometer (MODIS) data. The data-based mechanistic model is universalized to supply the LAI background information, and then the vegetation canopy radiative-transfer model (PROSAIL) is coupled to calculate reflectances with the same observation geometry as MODIS reflectance data. The ensemble Kalman filter (ENKF) is introduced to improve LAI estimation based on the difference between simulated and observed reflectances. Field measurements from seven Benchmark Land Multisite Analysis and Intercomparison of Products (BELMANIP) sites and reference maps from the Imagine-S project La Albufera, Spain site were used to validate the model. The results demonstrate that when compared with field measurements, the LAI time-series estimates obtained using this approach were superior to those obtained with the MODIS 500 m resolution LAI product. The root mean square errors (RMSE) of the MODIS LAI product and of the LAI estimated with the proposed method were 1.26 and 0.5, respectively. When compared with reference LAI maps, the results indicate that the estimated LAI is spatially and temporally consistent with LAI reference maps. The average differences between EDBM and the LAI reference map on the selected four days was 0.32.","Title: Detecting Forest Disturbance in Northeast China from GLASS LAI Time Series Data Using a Dynamic Model.\nYear: 2017\n\nAbstract: Large-scale forest disturbance often leads to changes in forest cover and structure, which imposes a great uncertainty in the estimation of the forest carbon cycle and biomass and affects other applications. In northeastern China, the Daxinganling region has abundant forest resources, where the forest coverage is about 30%. The Global LAnd Surface Satellite (GLASS) leaf area index (LAI) time series data provide important information to monitor the possible change of forests. In this study, we developed a new method to detect forest disturbances using GLASS LAI data over the Daxinganling region of Northeast China. As a dynamic model, the season-trend model has a higher sensitivity toward a seasonal change in LAI. Based on the accumulation of multi-year GLASS LAI products from 1997 to 2002, the dynamic model of LAI time series for each pixel is established first. The time-stepping modeling (TSM) process was designed by using the season-trend method, and sequential tests for detecting disturbances from a time series of pixels. Significant changes in the model parameters were captured as disturbance signals. Then, the near-infrared and shortwave-infrared bands of Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance are used as auxiliary information to distinguish the types of forest disturbances. Here, the algorithm led to the detection of two different types of disturbances: fire and other (e.g., insect, drought, deforestation). In this study, we took the forest region as the study area, used the 8-day composite GLASS LAI data at 1000-m spatial resolution to identify each pixel as a fire disturbance, other disturbance, or non-disturbance. Validation was performed using reference burned area data derived from Landsat 30 m imagery. Results were also compared with the MCD64 product. The validation results were based on confusion matrices showing the overall accuracy (OA) exceeded 92% for our method and the MCD64 product. Statistical tests identified that TSM's product accuracy is higher than that of MCD64. This study demonstrated that the TSM algorithm using a season-trend model provides a simple and automated approach to identify and map forest disturbance.","Title: Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests.\nYear: 2018\n\nAbstract: Significant gaps exist in our knowledge of the impact of leaf aging on canopy signal variability, which limits our understanding of vegetation status based on remotely sensed data. To understand the effects of leaf aging at the leaf and canopy scales, a combination of field, remote-sensing and physical modeling techniques was adopted to assess the canopy spectral signals of evergreen Cunninghamia forests. We observed an approximately 10% increase in Near-Infrared (NIR) reflectance for new leaves and a 35% increase in NIR transmittance for mature leaves from May to October. When variations in leaf optical properties (LOPs) of only mature leaves, or both new and mature leaves were considered, the Geometric Optical and Radiative Transfer (GORT) model-simulated canopy reflectance trajectory was more consistent with Landsat observations (R-2 increased from 0.37 to 0.82 similar to 0.89 for NIR reflectance, and from 0.35 to 0.67 similar to 0.88 for EVI2, with a small RMSE (0.01 to 0.02)). This study highlights the importance of leaf age on leaf spectral signatures, and provides evidence of age-dependent LOPs that have important impacts on canopy reflectance in the NIR band and EVI2, which are used to monitor canopy dynamics and productivity, with important implications for RS and forest ecosystem ecology.","Title: From Geometric-Optical Remote Sensing Modeling to Quantitative Remote Sensing Science - In Memory of Academician Xiaowen Li.\nYear: 2018\n\nAbstract: The academician Xiaowen Li devoted much of his life to pursuing fundamental research in remote sensing. A pioneer in the geometric-optical modeling of vegetation canopies, his work is held in high regard by the international remote sensing community. He codeveloped the Li-Strahler geometric-optic model, and this paper was selected by a member of the International Society for Optical Engineering (SPIE) milestone series. As a chief scientist, Xiaowen Li led a scientific team that made outstanding advances in bidirectional reflectance distribution modeling, directional thermal emission modeling, comprehensive experiments, and the understanding of spatial and temporal scale effects in remote sensing information, and of quantitative inversions utilizing remote sensing data. In addition to his broad research activities, he was noted for his humility and his dedication in making science more accessible for the general public. Here, the life and academic contributions of Xiaowen Li to the field of quantitative remote sensing science are briefly reviewed.","Title: The 3d Simulation Database Setup For The Realistic Scene Of The Typical Crops\nYear: 2004\n\nAbstract: Computer simulation is one of the vegetation canopy reflectance modeling method, which can realistically simulate the radiation interaction process within vegetation canopies and their dependence on various canopy structural parameters. In this paper, we mainly use the computer simulation methods, combined computer graphics with radiosity equation to simulate the radiative transfer process of the scene in both visible and near-infrared regions. There are five components in our 3D model: computer graphics technique to generate 3D objects; radiosity equation to describe the radiation exchange among the 3D objects, graphics based methods to compute view factors; radiosity computation and 3D image display of the objects; lastly introduced our 3D simulation database built up to put all information in it, such as simulated vegetation canopy's 3D structure files and the spectral data information of the vegetation and scene, in order to convenience users to query and retrieve correlating spectral information.","Title: A Prior Knowledge-Based Method to Derivate High-Resolution Leaf Area Index Maps with Limited Field Measurements.\nYear: 2017\n\nAbstract: High-resolution leaf area index (LAI) maps from remote sensing data largely depend on empirical models, which link field LAI measurements to the vegetation index. The existing empirical methods often require the field measurements to be sufficient for constructing a reliable model. However, in many regions of the world, there are limited field measurements available. This paper presents a prior knowledge-based (PKB) method to derivate LAI with limited field measurements, in an effort to improve the accuracy of empirical model. Based on the assumption that the experimental sites with the same vegetation type can be represented by similar models, a priori knowledge for crops was extracted from the published models in various cropland sites. The knowledge, composed of an initial guess of each model parameter with the associated uncertainty, was then combined with the local field measurements to determine a semi-empirical model using the Bayesian inversion method. The proposed method was evaluated at a cropland site in the Huailai region of Hebei Province, China. Compared with the regression method, the proposed PKB method can effectively improve the accuracy of empirical model and LAI estimation, when the field measurements were limited. The results demonstrate that a priori knowledge extracted from the universal sites can provide important auxiliary information to improve the representativeness of the empirical model in a given study area.","Title: Design of a Novel Spectral Albedometer for Validating the MODerate Resolution Imaging Spectroradiometer Spectral Albedo Product.\nYear: 2018\n\nAbstract: Land surface shortwave broadband albedo is a key parameter in general circulation models and surface energy budget models. Multispectral satellite data are typically used to generate broadband albedo products in a three-step process: atmospheric correction, for converting the top-of-atmosphere observations to surface directional reflectance; angular modeling, for converting the surface directional reflectance to spectral albedo of each individual band; and finally, narrowband-to-broadband conversion, for transforming the spectral albedos to broadband albedos. Spectroradiometers can be used for validating surface directional reflectance products and pyranometers or broadband albedometers, for validating broadband albedo products, but spectral albedo products are rarely validated using ground measurements. In this study, we designed a new type of albedometer that can measure spectral albedos. It consists of multiple interference filters and a silicon detector, for measuring irradiance from 400-1100 nm. The linearity of the sensors is 99%, and the designed albedometer exhibits consistency up to 0.993, with a widely-used commercial instrument. A field experiment for measuring spectral albedo of grassland using this new albedometer was conducted in Yudaokou, China and the measurements are used for validating the MODerate Resolution Imaging Spectroradiometer (MODIS) spectral albedos. The results show that the biases of the MODIS spectral albedos of the first four bands are -0.0094, 0.0065, 0.0159, and -0.0001, respectively. This new instrument provides an effective technique for validating spectral albedos of any satellite sensor in this spectral range, which is critical for improving satellite broadband albedo products.","Title: A Recursive Update Model for Estimating High-Resolution LAI Based on the NARX Neural Network and MODIS Times Series.\nYear: 2019\n\nAbstract: Leaf area index (LAI) remote sensing data products with a high resolution (HR) and long time series are in demand in a wide variety of applications. Compared with long time series LAI products with 1 km resolution, LAI products with high spatial resolution are difficult to acquire because of the lack of remote sensing observations in long-term sequences and the lack of estimation methods applicable to highly variable land-cover types. To address these problems, we proposed a recursive update model to estimate 30 m resolution LAI based on the updated Nonlinear Auto-Regressive with Exogenous Inputs (NARX) neural network and MODIS time series. First, we used a variety of HR satellite remote sensing observations to produce HR datasets for recent years. Historical low spatial resolution MODIS products were employed as background information and used to calculate the initial parameters of the NARX neural network for each pixel. Subsequently, one year's reflectance from the HR dataset was used as the new observation that was input into the NARX model to estimate the HR LAI of that year, and the background and HR data were then used for remodeling to update the NARX model parameters. This procedure was recursively repeated year by year until both MODIS background data and all HR data were involved in the modeling. Finally, we obtained an LAI time series with 30 m resolution. In the cropland study area in Hebei Province, China, the results were compared with LAI measurements from ground sites in 2013 and 2014. A high degree of similarity existed between the results for the two study years (RMSE2013 = 0.288 and RMSE2014 = 0.296). The HR LAI estimates showed favorable spatiotemporal continuity and were in good agreement with the multisample ground survey LAI measurements. The results indicated that for data with a rapid revisit cycle and high spatial resolution, the recursive update model based on the NARX neural network has excellent LAI estimation performance and fairly strong fault-tolerance capability.","Title: Evaluating the Spatial Representativeness of the MODerate Resolution Image Spectroradiometer Albedo Product (MCD43) at AmeriFlux Sites.\nYear: 2019\n\nAbstract: Land surface albedo is a key parameter in regulating surface radiation budgets. The gridded remote sensing albedo product often represents information concerning an area larger than the nominal spatial resolution because of the large viewing angles of the observations. It is essential to quantify the spatial representativeness of remote sensing products to better guide the sampling strategy in field experiments and match products from different sources. This study quantifies the spatial representativeness of the MODerate Resolution Image Spectroradiometer (MODIS) (collection V006) 500 m daily albedo product (MCD43A3) using the high-resolution product as intermediate data for different land cover types. A total of 1820 paired high-resolution Landsat Thematic Mapper (TM) and coarse-resolution (MODIS) albedo data from five land cover types were used. The TM albedo data was used as the spatial-complete high resolution data to evaluate the spatial representativeness of the MODIS albedo product. Semivarioagrams were estimated from 30 m Landsat data at different spatial scales. Surface heterogeneity was evaluated with sill value and relative coefficient of variation. The 30 m Landsat albedo data was aggregated to 450 m-1800 m using two different methods and compared with MODIS albedo product. The spatial representativeness of MODIS albedo product was determined according to the surface heterogeneity and the consistency of MODIS data and the aggregated TM value. Results indicated that for evergreen broadleaf forests, deciduous broadleaf forests, open shrub lands, woody savannas and grasslands, the MODIS 500 m daily albedo product represents a spatial scale of approximately 630 m. For mixed forests and croplands, the representative spatial scale was approximately 690 m. The difference obtained was primarily because of the complexity of the landscape structure. For mixed forests and croplands, the structure of the landscape was relatively complex due to the presence of different forest and plant types in the pixel area, whereas the other landscape structures were considerably simpler.","Title: Time Series High-Resolution Land Surface Albedo Estimation Based on the Ensemble Kalman Filter Algorithm.\nYear: 2019\n\nAbstract: Continuous, long-term sequence, land surface albedo data have crucial significance for climate simulations and land surface process research. Sensors such as the Moderate-Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer (VIIRS) provide global albedo product data sets with a spatial resolution of 500 m over long time periods. There is demand for new high-resolution albedo data for regional applications. High-resolution observations are often unavailable due to cloud contamination, which makes it difficult to obtain time series albedo estimations. This paper proposes an amalgamation albedo approach to generate daily land surface shortwave albedo with 30 m spatial resolution using Landsat data and the MODIS Bidirectional Reflectance Distribution Functions (BRDF)/Albedo product MCD43A3 (V006). Historical MODIS land surface albedo products were averaged to obtain an albedo estimation background, which was used to construct the albedo dynamic model. The Thematic Mapper (TM) albedo derived via direct estimation approach was then introduced to generate high spatial-temporal resolution albedo data based on the Ensemble Kalman Filter algorithm (EnKF). Estimation results were compared to field observations for cropland, deciduous broadleaf forest, evergreen needleleaf forest, grassland, and evergreen broadleaf forest domains. The results indicated that for all land cover types, the estimated albedos coincided with ground measurements at a root mean squared error (RMSE) of 0.0085-0.0152. The proposed algorithm was then applied to regional time series albedo estimation; the results indicated that it captured spatial and temporal variation patterns for each site. Taken together, our results suggest that the amalgamation albedo approach is a feasible solution to generate albedo data sets with high spatio-temporal resolution.","Title: Spectral collocation methods for nonlinear coupled time fractional Nernst–Planck equations in two dimensions and its convergence analysis\nYear: 2019\n\nAbstract: In this paper, a nonlinear coupled time fractional Nernst–Planck equation in two dimensions space is considered. Using properties of the Caputo fractional derivative and Riemann–Liouville fractional integral, the time fractional Nernst–Planck problem is transformed into a Volterra integral model with singular kernel equivalently. We propose a novelty spectral collocation method in time and space with a spectral expansion of Jacobi interpolation polynomial to discretize the model. We also derive the optimal rate of convergence of this method. Numerical results are presented to verify efficiency of collocation methods and spectral accuracy theory.","Title: A Novel Semantic Recognition Framework Of Urban Functional Zones Supporting Urban Land Structure Analytics Based On Open-Source Data\nYear: 2021\n\nAbstract: To solve problems related to urban land development, protection, and management, urban planners focus on achieving high precision and currency for fine-grained semantic recognition of urban functional zones (UFZs). The classification of discrete functional zones and qualitative recognition of UFZs have been well studied, but the precise recognition of UFZs with explicit depictions of socioeconomic urban functions has seldom been addressed. Thus, we propose a novel open-source data-guided semantic urban function recognition (OSD-SFR) framework to analyze UFZs and quantitatively link open-source data (OSD) with the Chinese national urban function classification code. The spatial relationship between the combined semantic database and the segmented urban zones data set was measured, graded, and categorized. Kernel density and statistical methods based on a single data source of points-of interest were used for comparative experiments. The results indicate that OSD-SFR yields more fine-grained delineations between urban functions and achieves more accurate recognition. Critical semantic information from different OSD sources is deeply integrated. This study provides a realistic reference, including detailed descriptions of the spatial distribution and morphological structure of UFZs, to support long-term city planning.","Title: Identifying Spatial and Temporal Characteristics of Land Surface Albedo Using GF-1 WFV Data\nYear: 2021\n\nAbstract: Land surface albedo (LSA) is an important parameter that affects surface-air interactions and controls the surface radiation energy budget. The spatial and temporal variation characteristics of LSA reflect land surface changes and further influence the local climate. Ganzhou District, which belongs to the middle of the Hexi Corridor, is a typical irrigated agricultural and desert area in Northwest China. The study of the interaction of LSA and the land surface is of great significance for understanding the land surface energy budget and for ground measurements. In this study, high spatial and temporal resolution GF-1 wide field view (WFV) data were used to explore the spatial and temporal variation characteristics of LSA in Ganzhou District. First, the surface albedo of Ganzhou District was estimated by the GF-1 WFV. Then, the estimated results were verified by the surface measured data, and the temporal and spatial variation characteristics of surface albedo from 2014 to 2018 were analyzed. The interaction between albedo and precipitation or temperature was analyzed based on precipitation and temperature data. The results show that the estimation of surface albedo based on GF-1 WFV data was of high accuracy, which can meet the accuracy requirements of spatial and temporal variation characteristic analysis of albedo. There are obvious geographic differences in the spatial distribution of surface albedo in Ganzhou, with the overall distribution characteristics being high in the north and low in the middle. The interannual variation in annual average surface albedo in Ganzhou shows a trend of slow fluctuations and gradual increases. The variation in annual albedo is characterized by \"double peaks and a single valley \", with the peaks occurring from December to February at the end and beginning of the year, and the valley occurring from June to August. Surface albedo was negatively correlated with precipitation and temperature in most areas of Ganzhou.","Title: Land Surface Albedo Estimation With Chinese GF-1 WFV Data in Northwest China\nYear: 2022\n\nAbstract: Land surface albedo (LSA) is one of the driving factors in the energy balance of surface radiation and the interaction between the earth and atmosphere. LSA is an important parameter that is widely used in surface energy balance, medium- and long-term weather forecasting, and global change studies. GF-1 wide field view (WFV) data provide a spatial resolution of 16 m and temporally intensive land surface observations, but efficient algorithm was still lacking for quantitatively land surface parameters estimation. It is essential to improve the data use ability by generating efficient land surface parameter retrieval algorithms. This study proposed an LSA retrieval algorithm by using GF-1 WFV data. Land surface bidirectional reflectance distribution function characteristic parameters were used to represent the non-Lambertian characteristic of land surface. The top of atmosphere (TOA) reflectance is simulated by the 6S radiative transfer model by considering non-Lambertian land surfaces. Linear regression is applied in the TOA reflectance, and LSA is simulated with the surface bidirectional reflectance characteristic parameters to build a lookup table. The proposed algorithm can estimate LSA with high accuracy according to the TOA reflectance without the complex multistep inversion process. The validation results of ground measurements in Northwest China for different land cover types show that the algorithm is effective, and the overall root mean square error was 0.036 when compared with field observation. The algorithm also shows great consistency with Landsat albedo data. The proposed algorithm is of great significance for improving GF data utilization.","Title: Compatible L2 norm convergence of variable-step L1 scheme for the time-fractional MBE model with slope selection\nYear: 2022\n\nAbstract: •An L2 norm error estimate is proven under a CSS-consistent time-step condition.•Time-step sizes for convergence, solvability and stability are of the same order.•Our estimate is robust and asymptotically compatible as the order α→1−.•The L1 scheme with an adaptive time-stepping strategy is practically reliable.","Title: Two energy stable variable-step L1 schemes for the time-fractional MBE model without slope selection\nYear: 2023\n\nAbstract: A variable-step L1 scheme is proposed for the time-fractional molecular beam epitaxy model without slope selection. By taking advantage of the convex splitting of nonlinear bulk, a sharp L2 norm error estimate is established under a convergence–solvability–stability (CSS) consistent time-step constraint, that is, the maximum step-size limit required for convergence is of the same order to that for solvability and stability (in certain norms) as the small interface parameter ϵ→0+. By using the discrete gradient structure of L1 formula, we build up a discrete variational energy dissipation law, which is asymptotically compatible with the classical energy dissipation law, as the fractional order α→1−. The stability and convergence of the stabilized convex splitting scheme are also investigated. The resulting scheme is shown to unconditionally preserve the variational energy dissipation law by adding a (2−α)-order stabilization term like τn1−α(ϕn−ϕn−1). Numerical experiments are presented to support our theoretical results."],"string":"[\n \"Title: A Simple Interpretation Of Ndvi-Ts Space Combining - Lai And Evapotranspiration\\nYear: 2004\\n\\nAbstract: The paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and analyzing transformation condition and the physical connotation and ecological meaning of the vegetation index-surface temperature feature space. Further, using the Temperature-Vegetation Dryness Index (TVDI), we explain the existent meaning of a triangular shape after NDVI arrives at saturated state (NDVI=1) by analyzing the relationship between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts will help us validate and update land surface models well.\",\n \"Title: Land surface leaf area index estimation based on time series multi-angular remote sensing data\\nYear: 2013\\n\\nAbstract: Time series leaf area index (LAI) derived from remote sensing data is a key parameter for environment researches especially on dynamic changes of land surface. In this study, a new approach was developed to retrieve LAI from time series Moderate Resolution Imaging Spectroradiometer (MODIS) multi-angular remote sensing data. Based on radiative transfer theory, we used Ross Thick-Li Sparse Reciprocal (RTLSR) kernel driven model to generate specific directional BRFs and corresponding anisotropy information, employed Scattering by Arbitrarily Inclined Leaves with Hotspot (SAILH) model to fill in missing data and Data-Based Mechanistic modeling (DBM) procedure to model and estimate time series vegetation LAI. The preliminary results indicated that the LAIs derived in this study have good agreement with ground LAI measurements and their continuity of the time series are superior to MODIS LAI product.\",\n \"Title: Landscape structure based super-resolution mapping from remotely sensed imagery\\nYear: 2011\\n\\nAbstract: Spatial resolution is one of the central issues in land cover mapping from remote sensing imagery, and sub-pixel land cover mapping is difficult and challenging in this domain. Soft classification can provide more information than hard classification. However, the spatial location of land cover compositions within each pixel is unknown. To solve this problem, super-resolution mapping methods have been developed in recent years. In this paper, a landscape structure based approach for super-resolution land cover mapping is introduced to generate super-resolution land cover maps from remote sensing data. The method was used to map simulated target images and a real landscape and the results indicate that this approach has the ability to reconstruct complicated landscape with linear features, and large or small patches relative to the pixel size.\",\n \"Title: Estimating leaf area index by coupling radiative transfer model and a dynamic model from multi-source remote sensing data\\nYear: 2009\\n\\nAbstract: Satellite remote sensing enables derivation of LAI globally at available spatial resolution and temporal frequency, and several LAI products have been produced. However, there are problems for the current global or regional LAI products, which restrict the application of these products. On the one hand, there are gaps between the large number of parameters of physical models and the small amount of data obtained by single sensor, which may cause the decrease in accuracy that LAI products should have. On the other hand, there are gaps between instantaneous observation of remote sensing and parameters which have change rules. Custom methods to retrieve LAI from remote sensing data are just involving the transient observations, discarding the information about process. To resolve these problems, we develop a methodology to retrieve LAI by involving diverse data from multiple sensor and LAI change rule. The methodology can take full advantage of the different band and angle information of time series MODIS and MISR data to improve the accuracy of the retrieved LAI over the MODIS LAI product compared to the field measured LAI data. And the retrieved LAI is also temporally continuous.\",\n \"Title: Study On The Albedo Of Winter Wheat At Growing Period With Different Spatial Scales\\nYear: 2004\\n\\nAbstract: This paper presents a general method and some preliminary results on validating MODIS albedo products, and how albedo changedingy in the winter-wheat's growing period. The available albedo observations are with different scales, including ground measurements and MODIS Albedo products. The study results show that the winter wheat's albedo of both the satellite observation scale anti ground measurements scale have the same trend at every growth stage.\",\n \"Title: Retrieval of forest canopy LAI directly from airborne full-waveform lidar data\\nYear: 2013\\n\\nAbstract: Forest canopy LAI is an important variable to the modeling of energy over regional and global scales. This paper explored the method to retrieve LAI and FAVD directly from full-waveform LiDAR data. At first, he full-waveform LiDAR data, including emitting and return laser waves, were denoised and decomposed. Based on the interaction model between LiDAR and forest, and the parameters of Gaussian decomposition, the forest FAVD was then inverted. Besides, the missing LiDAR data caused by high density forest and LiDAR system restrictions was filled based on the existing LiDARdata and CHM. At last, LAI of the research area was retrieved from the inversed FAVD, and validated by the LAI field measurement (r = 0.73, RMSE = 0.67).\",\n \"Title: The Bidirectional Reflectance Signature of Typical Land Surfaces and Comparison of MISR and MODIS BRDF Products\\nYear: 2008\\n\\nAbstract: The bidirectional reflectance distribution function (BRDF) of land surfaces specifies the behavior of surface directional reflectance as a function of illumination and viewing angles. The Moderate resolution Imaging Spectroradiometer (MODIS) and The Multiangle Imaging Spectroradiometer (MISR) provide their BRDF model parameters products respectively. Since the BRDF model parameters products are inverted from the observations with limited viewing directions for a given pixel, it is necessary to evaluate whether they can effectively characterize the directional reflectance in other viewing directions. In this study, we choose BRDF products data on four land cover types to learn their bidirectional reflectance signatures and to analyze the representation of MISR and MODIS BRDF model parameters products. The results show that: the MISR BRDF product shows hot spot more clearly than MODIS product, and both BRDF models' representative ability for extrapolating the reflectance at those directions without viewing dada tends to weaken when the viewing zenith angle increases.\",\n \"Title: Application of red edge variables in winter wheat nutrition diagnosis\\nYear: 2004\\n\\nAbstract: Remote sensing offers the potential to determine rapidly the physiological condition of crop over large areas. Canopy reflectance data selected at key growth stages of winter wheat were analyzed. It indicated that winter wheat growth phonological changes can be evaluated by red edge variables (REV) characteristics. Regression equations between chlorophyll concentration, nitrogen concentration, soluble sugar were established, prediction of foliar soluble sugar and chlorophyll concentration by red edge position, foliar nitrogen concentration by the amplitude of red edge, starch concentration by the near infrared plateau, leaf area index by the area of red edge peak are successful and feasible. For this purpose red edge variables can play a vital role in providing time-specific and time-critical information for precision farming, due to their capabilities in measuring canopy spectrum variability\",\n \"Title: A Temporally Integrated Inversion Method for Estimating Leaf Area Index From MODIS Data\\nYear: 2009\\n\\nAbstract: Multiple leaf area index (LAI) products have been generated from remote-sensing data. Among them, the Moderate-Resolution Imaging Spectroradiometer (MODIS) LAI product (MOD15A2) is now routinely derived from data acquired by MODIS sensors onboard Terra and Aqua satellite platforms. However, the MODIS LAI product is not spatially and temporally continuous and is inaccurate in many areas for some vegetation types. In this paper, a new algorithm is developed to estimate LAI from time-series MODIS reflectance data (MOD09A1). A radiative-transfer model is coupled with a double-logistic LAI temporal-profile model, and the shuffled complex evolution optimization method, developed at the University of Arizona, is used to estimate the parameters of the coupled model from the temporal signature in a given time window. Preliminary analysis using MODIS surface-reflectance data at flux sites was performed to validate this method. The results show that the new algorithm is able to construct a temporally continuous LAI product efficiently, and the accuracy has been significantly improved over the MODIS LAI product as compared to field-measured LAI data.\",\n \"Title: A Brief Introduction To The Standardized Spectral Database Of Typical Ground Objects\\nYear: 2004\\n\\nAbstract: The construction of standardized spectral database for typical objects of land surface aims to push development and application of quantitative remote sensing. The database is composed of four main parts including spectral database, model database, prior knowledgebase, and image database. The spectral database contains collection of existed spectral data, with quality evaluation, and collection of new spectral data together with corresponding parameters based on the new standard and criterion. The image database mainly contains a set of typical pica image data, which are synchronous to the ground spectral measurements obtained by different sensors. The prior, knowledgebase widely includes such as data of LULC in different scales, DEM data, phenology data etc.. The model database mainly contains models for spectral simulation, and includes also some general models for processing images. The model database is a key part of the spectral database. Though model simulation, database can provide characteristic spectral curves in different phases, scales and states. Furthermore, this database also includes demonstration of typical applications, which can make user to master application method of database quickly and exploit the application field of spectral database according to the detailed requirements. The construction of spectral database mainly provide some functions according to different users as follows: user management, upload and download of spectral data, management and transfer of prior knowledge, query of spectral data and corresponding parameters, model computing, query of remote sensing image, application demonstration, system management, user communication and so on.. The core product of database is to provide measured and simulated spectral data of typical ground objects.\",\n \"Title: Modeling directional effects from nonisothermal land surfaces in wideband thermal infrared measurements\\nYear: 2001\\n\\nAbstract: We present an algorithm to retrieve land surface temperatures from wideband thermal infrared measurements using the model of Li et al. (1999). Forward simulation and inversion demonstrates the method to be stable in the presence of observation noise. Results from inversions performed using field measurements show that errors are generally less than the uncertainty in the observations\",\n \"Title: Study On Scale Scope And Regional Consistency Of Earth Scene Heterogeneity\\nYear: 2004\\n\\nAbstract: ln our former research, we raised the concept of histo-variogram to describe the spatial heterogeneity among the earth objects compactly based on the analysis of the characteristics of other spatial analyzing methods such as variogram, information entropy. Just like all the other nature phenomenon, the spatial heterogeneity is also scale depended. That is, the heterogeneity of one kind of earth scene at a certain scale may become homogeneous at the other scale and vice versa. In current research, we want to find: 1. if there exists one scale scope in which the heterogeneity keeps relative stabilization. 2. if the heterogeneity of specific earth scent has regional coherence. This is very important for model selection or parameter adjustaion during inversion of quantitative remote sensing. We use the concept of \\\"total fractal dimension\\\" that rose in our former research to measure the hetero-eneitv of earth scene. The data source we used is stochastic sampled sub-regions from LUCC of Beijing district with different scales. The preparatory result shows that the heterogeneity of different earth scene has its specific scale scope and heterogeneity of most earth scenes have regional coherence.\",\n \"Title: Comparison of Radiative Transfer Models for Simulating Snow Surface Thermal Infrared Emissivity\\nYear: 2010\\n\\nAbstract: In this study, three analytical radiative transfer (RT) models and a numerical RT model are used to simulate the thermal-infrared (8-13 μm) emissivity spectra of snow surfaces. The single-scattering albedo and asymmetry factor calculated by Mie theory, in conjunction with that modified by two existing packing correction methods, are used as inputs to these RT models. The simulated snow emissivity spectra are compared with in situ measurements. The best models for simulating snow emissivity spectra are identified at the conclusion of this paper.\",\n \"Title: An approach on improving MODIS albedo product by using the information from MODIS LAI product\\nYear: 2012\\n\\nAbstract: Surface albedo is an important parameter in modeling climate processes as it determines the energy budget of the earth's surface. Operational surface albedo products are available from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. However, due to the factors associated with weather, sensors and algorithms, albedo products from satellite observations often have many gaps. In this paper, we reformed the semi-empirical kernel-driven model to express the relation between the bidirectional reflectance distribution function (BRDF) and the Leaf Area Index (LAI). Within a small region, the soil properties under plant canopies are similar, therefore the reflectance is unanimous. When the land cover types are identical and the LAI values are same, the canopy top reflectance should be same. Thus, within a small region, the pixels of same properties have the same reflectance. For one pixel, if the MODIS albedo product has no retrieval but MODIS LAI product has high quality retrieval, the LAI information can be used to filled the MODIS albedo data gaps. A comparison indicates that the filled data conform well with the in-situ measurements albedo.\",\n \"Title: Study On Forest Vegetation Classification Based On Multi-Temporal Remote Sensing Images\\nYear: 2008\\n\\nAbstract: It is very difficult to classify forest vegetation in mountain areas because of the impact of complex terrain. A new method, classification of forest vegetation based on multi-temporal remote sensing, is proposed in this paper. The forest vegetation could get better classification precision by avoiding the interactions of different plants with multi-temporal images. So it enhanced the separability of coniferous forest and broad leaf forest. The classification result showed that the accuracy Could be greatly improved by using multi-temporal remote sensing images. The overall accuracy and kappa coefficient were 81.3% and 0.72, respectively. So the method delivered in this essay has obviously technological advantages and important application potentiality in forest vegetation classification.\",\n \"Title: Kernel -based vegetation index and its validation with different-scale BRDF data sets.\\nYear: 2004\\n\\nAbstract: Traditional vegetation indices are usually constructed by using red and near-infrared band reflectance data under single solar incidence-observation geometry. However, because of the anisotropy of the earth surface's reflectance, vegetation indices acquired from different solar- incidence observation geometries exhibit lots of variances. Meanwhile, most of those indices only utilize vegetation's spectral information, and anisotropic reflectance of vegetation is considered as a disturbing factor rather than a source of vegetation's structural information. In this paper, kernel-based vegetation index (KVI) is constructed based on the semi-empirical kernel-based BRDF model parameters. Validation results of ground measured bidirectional reflection data of different vegetation types show: kernel-based vegetation index has better linear relationship with corresponding vegetation's leaf area index (LAI) than widely used normalized difference vegetation index does. The results of upscaling KVI from local scale to global large scale suggests the effect of scale needs to be considered when using it to different scale data sets. This study suggests that KVI provides a new method of better using multi-spectrum and multi-angle reflectance data, and has certain potential for multi-angular remote sensing applications.\",\n \"Title: Comparison and analysis of two fractal dimension computing algorithms for upscaling remote sensing Leaf Area Index map\\nYear: 2012\\n\\nAbstract: The Leaf Area Index (LAI) values derived from remote sensing images with different resolutions can be different, because of the heterogeneity of land surface. To validate the coarse resolution LAI product, the in situ LAI measurements and the high resolution LAI map need to be upscaled to the coarse resolution(such as 1 km). As the principle of fractal geometry has been applied to describe the irregular distribution of vegetation, the measured LAI can be upscaled using Fractal Dimension (FD) which is the key parameter of fractal geometry. In this paper two FD computing algorithms, Triangular Prism Surface Area method (TPSA) and Differential Box Counting algorithm (DBC), were compared in two aspects. One aspect was the ability of describing heterogeneity of LAI in different landscapes; another was the spatial distribution of FD and upscaled LAI. The log-log curves of computing algorithms showed that TPSA performs better to capture the difference between different landscapes than DBC algorithm does. Also TPSA can detect the scale inflexion of LAI spatial distribution but the DBC can't. The pattern of FD and upscaled LAI map using TPSA is similar with the real pattern of vegetation, while the FD and upscaled LAI map using DBC algorithm cannot capture the real pattern of vegetation.\",\n \"Title: Comparison of the inversion ability in extrapolating forest canopy height by integration of LiDAR data and different optical remote sensing products\\nYear: 2012\\n\\nAbstract: Forest canopy height is an important variable to the modeling of energy over regional and global scales. This paper first examined the relationship between field-surveyed canopy height and LiDAR-derived canopy height, regression between them had an RMSE and R2 value of 0.94 m and 0.64. To extrapolate the LiDAR height to a continuous area, we compared the ability of four sources of optical remote sensing data (MODIS BRFs, MODIS NBAR, MISR and SPOT data) in predicting the LiDAR measured canopy height. Multivariate linear regression and single variable nonlinear regression models were developed, and the best model accurately predicted the LiDAR height using MODIS BRFs data (RMSE=1.2 m, R2= 0.67). This model was applied to the whole study area and finally the canopy height map of the study area was generated.\",\n \"Title: Studies on methods for quality assessment of crop spectral data\\nYear: 2004\\n\\nAbstract: In the process of measurement, a number of factors will affect the quality of data. Therefore, data must be verified and assessed before their applications. This paper discussed some methods for quality assessment of crop spectral data, which include methods of analysis of spectral characteristics, statistical test and spectral simulation. The method of spectral analysis compares measured spectra with the reference spectrum, and analyzes the location of wave crest, wave trough and the shape, intensity of spectral reflectance curves. The method of statistical test consists of shape similarity test and intensity test. The shape similarity test analyzes the correlation between measured spectral data and the reference spectral datum over the special wavelength range and assesses quality of the measured data by the correlation coefficients. The intensity test calculates the mean value and standard deviation of spectral data, and forms a spectral zone around the mean value. We consider it as the abnormal one if one spectral curve goes beyond the spectrum zone. The method of spectral simulation mainly compares measured spectra with simulated spectra by combined PROSPECT-SAIL model. Results show these methods of quality assessment are feasible\",\n \"Title: Land Surface Parameters Retrieval Using Time Series Remotely Sensed Observations\\nYear: 2007\\n\\nAbstract: Leaf area index (LAI) is an important parameter for estimating growth status of crops. An important method for retrieving LAI from remotely sensed observations is by the canopy reflectance model inversion. But many model inversion methods didn't take into account the relationship between estimated LAIs in different crop growth stages. In this research, we consider the crop growth model which describe how LAI change with crop growth stages. The main method for this research is assimilating multiple crop's canopy reflectance observed in different growth stages into the cost function for LAI retrieval. Data assimilation algorithm we used in this study is the variation algorithm. The model inversion results have showed that time series observations of canopy reflectance can decrease uncertainty of estimated LAI in model inversion.\",\n \"Title: Estimating leaf area index by fusing MODIS and MISR data]\\nYear: 2006\\n\\nAbstract: Moderate-resolution imaging spectrometer (MODIS) and multi-angle imaging spectroradiometer (MISR) are two important sensors on TERRA satellite. The authors can have more spectral and multi-angular observations on the land surface objects by combining these two datasets. In the present paper, both MODIS and MISR observations were combined to estimate leaf area index (LAI) of land surface. The adjoining model and trust-region optimal algorithm were introduced into the framework of physical model inversion to speed up the running of the model inversion algorithm. And the algorithm allows the prior knowledge on the retrieved parameters to be input into the inversion procedure. The uncertainty and sensitivity matrix (USM) based analysis is helpful for selecting the observed data subset with more information and less noise to retrieve LAI. The measured LAI in situ and estimated LAI from ETM data were scaling-up to MODIS/MISR LAI product scale, and were taken as the ground truth to evaluate the new approach. The result suggests that combining two sensors datasets can improve the accuracy of LAI estimation, and the developed inversion method in this paper can be applied to the large area remote sensed image data effectively.\",\n \"Title: An Improved Algorithm to Produce Spatio-Temporally Continuous MODIS Albedo Product in China\\nYear: 2008\\n\\nAbstract: Surface albedo is one of the key radiation parameters required for modeling of the Earth's energy budget, and many ecological and climate models usually require high quality consistent surface albedo as inputs and validation sources. The Moderate Resolution Imaging Spectroradiometer (MODIS) has been providing surface albedo products periodically. However, due to influence of weather, sensors and algorithms, MODIS albedo products often have many gaps and low quality pixels. This paper proposed an improved spatio-temporal smoothing algorithm utilizing multilevel procedure that combines spatial interpolation and tempora smoothing to get better albedo products based on multiyear observations and high quality neighboring pixels. Compared with field measurements, the improved albedo products in China based on MOD43B3 show better correlation with the measured surface albedo with the overall root mean squared errors around 0.0767. The generated albedo products may be applied in land surface models.\",\n \"Title: Uncertain data mining from spectra library under Bayesian network model\\nYear: 2004\\n\\nAbstract: Uncertainty is an inherent property of Remotely Sensed data. Under the architecture of Bayesian network, which can integrate the quantitative and qualitative knowledge into a comprehensive probabilistic knowledge representation and inference environment, this paper presents a model for data mining from spectra library. Using the filed measured data to drive the model, we obtain the crop structure variables such as Leaf Area Index (LAI) information, e.g. its probability distribution, which can be looked as the priori knowledge of the parameter during the process of inversion.\",\n \"Title: Uncertainty Analysis For Ndvi Using The Physical Models\\nYear: 2004\\n\\nAbstract: NDVI is the most widely applied vegetation index, it can indicate the information of growth status, LAI, et al. However, NDVI is also affected by the atmosphere conditions, soil background, view conditions and so on. In the Paper, we analyses the effects of chlorophyll, surface soil moisture, the ratio of sky light, view zenith and sun zenith on NDVI under different LAI using the leaf radiative transfer model PROSPECT and canopy reflectance model SAIL., and find the sensitive factors and ranges.\",\n \"Title: Development of the Adjoint Model of a Canopy Radiative Transfer Model for Sensitivity Study and Inversion of Leaf Area Index\\nYear: 2008\\n\\nAbstract: Many canopy reflectance models have been developed in the last decades and used for estimating land surface biogeophysical variables, such as leaf area index (LAI), from satellite observations through optimization procedures. In most studies, the derivative information of the canopy reflectance model has not been used effectively, which limits this approach for regional and global applications. Th...\",\n \"Title: A new algorithm on delineation of management zone\\nYear: 2005\\n\\nAbstract: The delineation of management zones is an economical and effective measure for the variable-rate application in precision agriculture. The methods of empirical and unsupervised classification have been used by many researchers in the delineation of management zones, but these methods are only built upon the information of attributes in every spatial cell, and the spatial relationships and their spatial interaction between cells are not considered. AS a result, there are many isolated cells or patches in the zoned map, this is not advantageous for the operation of the variable-rate application. Based on the traditional k-means cluster (K-M) and the spatial autocorrelation, a new method, spatial contiguous k-means clustering algorithm (SC-KM), was developed in this study. According to the spatial variability of wheat growth under within-field level extracted from OMIS image of the key growth stage, management zones were delineated by using K-M and SC-KM methods. Two evaluation indices were employed to evaluate the zoned results of the above mentioned two methods .The results showed that the sum of the weighted variance of the corresponding within-zones based on the two methods appeared no significant difference, and that the SC-KM method could remove lots of isolated cells or patches and improved the continuity of the corresponding management zone map, compared with the K-M method. The zoned result based on the SC-KM method can be used as the variable management unit for precision agriculture and can be used to advise the sampling of subsequent soil or crop.\",\n \"Title: Studies on urban areas extraction from landsat TM images\\nYear: 2005\\n\\nAbstract: In this paper, extracting urban areas from Landsat TM images is studied. We proposed a new method for urban and rural residential areas extraction. A classification example based on barren index(BI) is given in this article. We classified the image with several methods and compared the classification results. The result indicates this proposed method based on BI has obvious advantages over conventional multi-band spectral data classification. Classification map created by this method suffers less from a lack of spatial coherency and has a high classification accuracy. © 2005 IEEE.\",\n \"Title: Validation of BRF data based on computer simulation model.\\nYear: 2005\\n\\nAbstract: At present, modeling bi-direction reflectance of vegetation canopy scene, produced by computer simulation and a radiosity-graphics combined method (RGM), has already made preliminary progress. In order to qualify the simulated data, in this paper, taking winter wheat as an example, besides comparing computer simulated data with measured data, we also use anther method: regarding simulated data as the prior-data and condition data of SAIL model to inverse the structure parameters of vegetation canopy, such as LAI, ALA and component spectrum, which were the input parameters of computer simulation. Next, comparing these SAIL modeled data with the input data of computer simulation. Thus we can get the precision of LAI, and validate the reliability of BRF data based on computer simulation. On the other hand, evaluating the quality of algorithms and models used by computer simulation. Some conclusions are drawn from the investigation:(1) LAI is the important structure parameter for vegetation canopy scene, and we can control the whole scene and Its radiation regime only using LAI;(2)BRF data based on computer simulation model is reliable and its precision can meet the actual demands. So these BRF data can be considered as measured data to carry on research under certain conditions. ©2005 IEEE.\",\n \"Title: Leaf area index estimation from MODIS data using the ensemble Kalman smoother method\\nYear: 2010\\n\\nAbstract: The new data assimilation algorithm is developed to estimate LAI from time-series MODIS reflectance data (MOD09A1). The canopy radiative transfer model (ACRM) is coupled with an empirical LAI dynamic model, and the ensemble Kalman smoother (EnKS) is used to estimate the parameters of the coupled model from MOD09A1 data. The preliminary analysis using MODIS surface reflectance data at some AmeriFlux network sites was performed to validate this method. The results show that the algorithm is helpful to produce the temporally continuous LAI estimation of cropland efficiently. By comparing with the field measured LAI, the retrieved LAI has been significantly improved and shown more smooth in time series than the MODIS LAI product.\",\n \"Title: Use of General Regression Neural Networks for Generating the GLASS Leaf Area Index Product From Time-Series MODIS Surface Reflectance\\nYear: 2014\\n\\nAbstract: Leaf area index (LAI) products at regional and global scales are being routinely generated from individual instrument data acquired at a specific time. As a result of cloud contamination and other factors, these LAI products are spatially and temporally discontinuous and are also inaccurate for some vegetation types in many areas. A better strategy is to use multi-temporal data. In this paper, a method was developed to estimate LAI from time-series remote sensing data using general regression neural networks (GRNNs). A database was generated from Moderate-Resolution Imaging Spectroradiometer (MODIS) and CYCLOPES LAI products as well as MODIS reflectance products of the BELMANIP sites during the period from 2001-2003. The effective CYCLOPES LAI was first converted to true LAI, which was then combined with the MODIS LAI according to their uncertainties determined from the ground-measured true LAI. The MODIS reflectance was reprocessed to remove remaining effects. GRNNs were then trained over the fused LAI and reprocessed MODIS reflectance for each biome type to retrieve LAI from time-series remote sensing data. The reprocessed MODIS reflectance data from an entire year were inputted into the GRNNs to estimate the 1-year LAI profiles. Extensive validations for all biome types were carried out, and it was demonstrated that the method is able to estimate temporally continuous LAI profiles with much improved accuracy compared with that of the current MODIS and CYCLOPES LAI products. This new method is being used to produce the Global Land Surface Satellite LAI products in China.\",\n \"Title: Validation Of Scale Effect Based On Computer Simulation Model\\nYear: 2004\\n\\nAbstract: With the developing of satellite technology, more and more sensors, based on various resolutions and functions, are launched to the sky to perform their missions. Enormous data are sent back to the earth stations. In deriving surface parameters using these remotely sensed data, the transportability of algorithms from one resolution to another often cause the scale effect because of the surface heterogeneity on the earth which can induce the change of reflectance.The problem, that the change of reflectance data affected by discontinuity as part of surface heterogeneity impacts the retrieval of vegetation leaf area index (LAI), is addressed in this paper. Two cases, inducing the scaling issue in deriving surface parameters of interest, are considered here. One is the discontinuity between contrasting cover types within a mixed scene, the other is the non-linear relationship of NDVI and LAI. Therefore, it is necessary to apply the correction based on NDVI-LAI relationships to modify scaling problem.In the processing, considering the field of wheat, firstly a series of 3D scenes with wheat and soil mixed are made based on the field measurement; secondly, computer simulation model--the method of radiosity, which can calculate the balance of light energy in the simulated scenes, is used to model BRF(Bi-directional Reflectance Factor) of these scenes. If the NDVI-LAI relationship from homogeneous scenes can be taken as standard, the relationship from heterogeneous scenes will be modified according to contextural parameter. Some conclusions are drawn from the investigation: (1) different distributional contextures of vegetation even with the same LAI affect the reflectance heavily; (2) we compare the reflectance simulated by the method of radiosity with the mean reflectance calculated using the area-weighted linear relationship of reflectance from components, and find that the accuracy of the mean reflectance can be accepted so that the linear equation to calculate the reflectance of mixed pixels is reasonable to relate images with high and low resolution; (3) using contextural parameter for quantifying the scale effect can get promising results.\",\n \"Title: A data-based mechanistic assimilation method to estimate time series LAI\\nYear: 2013\\n\\nAbstract: In recent years, time series remote sensing data products have been assimilated into the coupled crop growth model and the radiative transfer model to improve the time series LAI estimation. However, due to the large number of input parameters to the crop growth model, the applications of the crop growth models for regional use is restricted. This paper proposed a data-based mechanistic assimilation method for estimation of the time series LAI from Moderate Resolution Imaging Spectroradiometer (MODIS) data. By coupling a revised universal data-based mechanistic model (LAI_UDBM) with a vegetation canopy radiative transfer model (PROSAIL), The proposed method applies the Ensemble Kalman Filter (ENKF) method to improve the estimation accuracy. Results indicate that the time series LAI estimated by this approach is superior to the MODIS LAI. Furthermore, because the model does not require the historical observation of every pixel, it is applicable over a wider range of uses.\",\n \"Title: An Angular Index to Indicate Surface Heterogeneous Behaviors from MODIS\\nYear: 2008\\n\\nAbstract: An anisotropic flat index (AFX) is among the operational BRDF and albedo products offered in both the V004 and V005 reprocessed versions. We examine this BRDF shape indicator with 20 ground multiangular data sets as well as MODIS satellite samples, and find that the AFX routinely captures the BRDF shape. An AFX < 1.0 indicates a dome shaped anisotropic pattern with prominent backscatter peak reflectances, and strong retro solar view angle (hotspot) maximum reflectances; an AFX = 1.0 approximately indicates a Lambertian surface; and an AFX > 1.0 corresponds to a bowl shaped anisotropy pattern. For green vegetation, the BRDF shape is related to canopy architecture. Therefore, the behavior of the AFX provides an opportunity to infer canopy structure of the surface cover that produces the anisotropic effect.\",\n \"Title: Monitoring of wheat yellow rust with dynamic hyperspectral data\\nYear: 2004\\n\\nAbstract: The objective in this study was to develop proper vegetation indices for prediction of soil irrigation demanding under vegetation covering conditions. The traditional method for the winter wheat yellow rust field survey is time consuming. It was discussed of the selection method of characteristic spectral bands and the establishing of inversion model to monitor winter wheat yellow rust using hyperspectral data in this study. The correlation coefficients between selected vegetation index and disease incidence (DI) at infected stages. Inversion models between DI and vegetation index such as normalized difference vegetation index (NDVI), ratio vegetation index (RVI), transformed vegetation index (TVI) were used to monitor yellow rust. The multi-temporal hyperspectral airborne images were acquired from winter booting stage to milking stage, and the yellow rust disease of winter wheat was analyzed using hyperspectral images. Compared with healthy wheat, spectral reflectance of disease wheat was higher in 560-670 nm bands but lower in near infrared bands and the absorption depth of chlorophyll in red band and reflectance peak in green band are relatively reduced. A novel spectral index for yellow rust indices was presented, and the degree and area of yellow rust disease were successfully remotely sensed from the multi-temporal hyperspectral data based on spectral index\",\n \"Title: Comparison of three indirect field measuring methods for forest canopy leaf area index estimation\\nYear: 2009\\n\\nAbstract: The Effective Plant Area Index (PAIe) of forest canopy is an important parameter in the canopy reflectance modeling and validation. PAIe can be transformed to leaf area index (LAI) with clumping index. But it is still very difficult to obtain its ground truth value by in situ measurement. In this study, we measured PAIe of 3 typical wood land sites in China by means of three indirect optical techniques: plant canopy analyzer LAI-2000, TRAC, and Digital Fisheye Camera. The 5 measured stands include Qinghai spruce, peach, poplar, willow and silver chain. In this paper, the forest canopy PAIe measured by those three instruments is compared firstly. Then our new approach is how to use the three measured data to get the better PAIe estimation with less overall error. The method of minimizing overall error is adopted to produce PAIe of the sample plots in our study sites, which has less overall error comparing with the PAIe measured by each individual instrument. This approach is also validated by using computer simulated wide-angle viewing pictures when true LAI/PAIe values are given.\",\n \"Title: A Stepwise Refining Algorithm of Temperature and Emissivity Separation for Hyperspectral Thermal Infrared Data\\nYear: 2010\\n\\nAbstract: Land surface temperature (LST) and land surface emissivity (LSE) are two key parameters in numerous environmental studies. In this paper, a stepwise refining temperature and emissivity separation (SRTES) algorithm is proposed based on the analysis of the relationship between surface self-emission and atmospheric downward spectral radiance in a narrow spectral region. The SRTES algorithm utilizes t...\",\n \"Title: A method of upscaling ground measurements of Leaf Area Index based on Taylor Series expansion Model\\nYear: 2012\\n\\nAbstract: The ground measurements of Leaf Area Index (LAI) are usually used to validate the LAI estimated using remote sensing observations. The main problem encountered in the validation is the scale mismatch between the sampling area of ground measurements and coarse-resolution image pixel, especially when those sampling area are not ideal homogenous. This study introduced a new approach of upscaling ground measurements to the coarse-resolution scale for the validation of LAI estimations. This upscaling method was based on the Taylor Series expansion Model (TSM). The high-resolution images were used to provide auxiliary information at the sub-pixel scale of coarse-resolution image pixel. The possible error associated with this method is derived from the neglection of the third- and higher-order TSM terms and the uncertainty of the empirical model. The upscaled ground measurements with upscaling error smaller than half of eigenaccuracy could be used for validation of LAI estimations with coarse resolution.\",\n \"Title: Use of an ensemble Kalman filter for real-time inversion of leaf area index from MODIS time series data\\nYear: 2009\\n\\nAbstract: It is an urgent need for natural disaster monitoring to generate biophysical variables data with high accuracy timely from remotely sensed data. A real-time inversion method to estimate leaf area index (LAI) using MODIS time series reflectance data (MOD09A1) is developed in this paper. A seasonal autoregressive integrated moving average (SARIMA) model is used to derive LAI climatology. A dynamic model is then constructed based on the climatology from the SARIMA model to evolve LAI in time, and used to provide the short-range forecast of LAI. Predictions from the model are used with the ensemble Kalman filter (EnKF) techniques to recursively update biophysical variables as new observations arrive. The validation results show that the real-time inversion method is able to produce a relatively smooth LAI product efficiently, and the accuracy is significantly improved over the MODIS LAI product.\",\n \"Title: A Simple Data Assimilation Method for Improving Estimation of MODIS LAI Time-series Data Products Based on the 2-Dimensional LMS Adaptive Filter\\nYear: 2006\\n\\nAbstract: Leaf area index (LAI) is an important parameter for describing vegetation canopy structure in the terrestrial ecosystem on the global, continental and regional scales. In this paper, a simple data assimilation method for improving estimation of MODIS LAI time-series data products based on a new 2-D LMS (two-dimensional least mean square) adaptive filter was proposed. Firstly, The new 2-D LMS adaptive filter algorithm is introduced and analyzed. Secondly, A simple data assimilation method for improving estimation of MODIS LAI time-series data products based on the new 2-D LMS adaptive filter and quality control data of MODIS LAI is proposed. Finally, the experiments are performed based on the simple data assimilation method using MODIS LAI data products from 2000 to 2005 of southwestern China.\",\n \"Title: Crop Leaf Area Index Observations With a Wireless Sensor Network and Its Potential for Validating Remote Sensing Products\\nYear: 2014\\n\\nAbstract: The collection of ground measurements for validating remotely sensed crop leaf area index (LAI) is labor and time intensive. This paper presents an automatic measuring system that was designed based on a wireless sensor network (WSN). The corn LAI was continuously observed from June 25 to August 24, 2012. Approximately, 42 in situ WSN measurement nodes were used in a 4 ×4 km2 area in the Heihe watershed of northwest China. The data were analyzed in three ways: 1) a comparison with LAI-2000, 2) a daily and 5-day aggregated time series analysis, and 3) a comparison with a Moderate Resolution Imaging Spectroradiometer (MODIS) LAI using both a ground LAINet LAI and a scaled-up LAI through inversion of Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) data. The preliminary results indicated that the measured LAI values from the LAINet were correlated with the values derived from LAI-2000 (R2 from 0.27 to 0.96 with an average of 0.42). When compared with the daily crop LAI growth trajectory, the performance of the measurement system was improved by using the data that were aggregated over a 5-day window. When compared with MODIS LAI, we found that the spatial aggregation values of the ground LAINet observations and the scaled-up ASTER LAI were identical or similar to the MODIS LAI values over time. With its low-cost and low-energy consumption, the proposed WSN observation system is a promising method for collecting ground crop LAI in flexible time and space for validating the remote sensing land products.\",\n \"Title: Uncertainty of remote sensing model inversion and a synthetical inverse scenario\\nYear: 2002\\n\\nAbstract: The sources of the inverse error of remote sensing physical models are analyzed and divided into two groups. From the point of view of controlling these errors, a synthetic inverse scenario is put forward. A case study using simulated data shows that this scenario is better than ordinary methods in robustness and global convergency.\",\n \"Title: Approach and validation on land surface albedo retrieval using multiangular remote sensing observations\\nYear: 2002\\n\\nAbstract: The main problem in the validation is that the field-measured albedo is different in scale from the albedo estimated using remote sensing data. The albedo-meter based field measurement is over a small area. On the contrary, the spatial resolution of the MODIS albedo production is about 1 km. Another problem is the different wavebands or albedo-meter and MODIS sensor. As a solution, we suggest to use the field multiangular measurements data that is captured in a small field of view (FOV) to retrieve the albedo by Ambrals model inversion. As a result, the retrieved albedo is comparable with that measured by albedo-meter since they have the same scale. At the same time, the effect of wavebands difference is also corrected. In the second step, we extend this method to the airborne MARS observations of the same target. Scaling-up can be considered based on the two inverted albedos. The retrieved albedo from airborne data can be validated using field measurement too. Finally, the airborne retrieved albedo can be used to validate the MODIS albedo production. In this framework, the field measured data sets come from a large satellite-airborne-ground synchronous experiment that was taken in Shunyi, which is in the north of Beijing, in April of 2001.\",\n \"Title: A priori knowledge in the inversion of linear kernel-driven BRDF models\\nYear: 2002\\n\\nAbstract: A priori knowledge can come from field measurements of bidirectional reflectance factors for various surface cover types. How to express and use this kind of knowledge is very important currently. 73 sets of field observations are used to explore the possible expression of a priori knowledge in linear kernel-driven BRDF models in this paper.\",\n \"Title: BRDF modeling and inversion of structure parameters for sparse vegetation canopy\\nYear: 2002\\n\\nAbstract: Multi-angular remote sensing became a hot topic after the non-Lambert characteristic of the Earth's surface had been accepted popularly. A large amount of multi-angular remote sensing data has been obtained with the launch of multi-angle remote sensing sensors. Therefore, modeling of the bi-directional reflectance distribution function (BRDF) for the Earth objects is one of the main subjects at present. A large satellite-airborne-ground synchronous remote sensing experiment was carried out during March 29 to May 10, 2001 at Shunyi, China. The main observation target in this experiment is focused on winter wheat. To describe the BRDF of winter wheat in its early growing stages, we propose a geometric-optical model that is suitable for sparse vegetation, and then try to retrieve the structure parameters based on this model using the field measurements. The purport of the model and its inversion is to inspect the ravages of drought on the wheat just as it is turning green. The winter wheat in our measurement field is sparse and disperses without clear row structures in its turning-green stage. Typical row structure based models and uniform structure based models are not suitable. Our model is developed based on the Li-Strahler geometrical-optical model proposed in 1985. Each cluster of wheat is treated as a hemi-ellipsoid in this model. All of the leaves in the cluster are assumed to cover the hemi-ellipsoid randomly. Leaf area index and leaf angle distribution are two important parameters that are related to the surface area of the hemi-ellipsoid and the leaf distribution on this surface respectively. Leaf angle distribution is also related to the shape of the hemi-ellipsoid. Due to the large uncertainty of the number of hemi-ellipsoids in a unit area, we retrieve this parameter based on our model using the most sensitive samples first, and then treat it as a priori knowledge in the later inversion. The next stage is studying how to use multi-angle remote sensing data to invert vegetation structure parameters.\",\n \"Title: The BRDF model and analysis of hotspot effect of row crops\\nYear: 2002\\n\\nAbstract: According to the Li-Strahler model, a BRDF model of row structure with gap, in which three components and six paths are taken into account, is established through analysis of the process of radiation transfer. The model is verified by the data obtained in the Satellite-Airborne-Ground Synchronous Quantitative Remote Sensing Experiment implemented from March 29 to May 10 in 2001, in Shunyi, Beijing, China. As is shown, the model can demonstrate effectively the reflection of crops with row structure.\",\n \"Title: A thermal bidirectional gap model for row crop canopies\\nYear: 2002\\n\\nAbstract: We propose a thermal bidirectional gap model to describe the thermal directional emission from row crop canopies. An important concept of overlap index is used in this model to express the correlation between the gaps in the Sun and view directions. Detailed directional thermal emissions, row structure, LAI, component temperatures were measured in the experiment taken in Shunyi China, 2001. These data are used to validate our model. As an illustration, we compared our bidirectional gap model with the model that doesn't consider gaps (Kimes model) and the model only consider gaps in view direction. It is found that our model gives out the closest results to the field measurements.\",\n \"Title: Local statistic-based fusion of MIVIS VNIR and simulated TIR images\\nYear: 2002\\n\\nAbstract: Local statistic-based fusion algorithms are discussed, which can be applied to fuse high-resolution VNIR images and a single low-resolution TIR image. These algorithms are based the experiments that structural information of observed objects in visible and near-infrared spectral range (VNIR) is essentially correlated with the environmental information (especially moisture information) in thermal infrared spectral range (TIR). The local is performed at three scales. This algorithm can be useful method to merge the TIR image and VNIR images.\",\n \"Title: Design and implementation of knowledge base for quantitative remote sensing\\nYear: 2002\\n\\nAbstract: The remotely sensed images can be understood and analyzed better through comparing the remote sensing spectrum and the spectrum with known land surface structure and physical chemistry parameters. It is unavoidable to compute land surface spectrum based on prior knowledge and remote sensing physical models when we cannot obtain the measured spectrum on suitable time and pixel size. The remote sensing knowledge base integrates data, image, and physical models for quantitative remote sensing. Here in our remote sensing spectral knowledge base, the digital elevation model, land cover and land cover maps and soil map are restored in the spatial database. The climatic changes and spatial patterns of vegetation are restored in the expert system. And component spectrum of vegetation, soil, water, snow, minerals, man-made object are measured and also stored in the database. It is apparent that they themselves have data systems and the systems usually are different with input and output parameter systems of remote sensing physical models. In order to solve the discrepancies, metadata of data and model are put forward. About design of the knowledge base, defining and organizing metadata is key task. Accordingly to data, image and model in the knowledge base, the metadata also consists of metadata about data, metadata about image, and metadata about model. Metadata describes formation, quality and meaning of data, image and model. Data exchanges between database, image base and model base are found on the metadata, and is coordinated by an expert system based on rule, so data extraction and re-organizing will obtain flexible as large as possible. The data-engine extracts data from databases and transfers the data between database and model base, and the model-agent selects suitable models to extend the structure and physical chemistry parameters, and extract land surface facts, finally compute the land surface spectrum on multi-temporal & spatial scales.\",\n \"Title: Modeling the albedo of mixed vegetation canopy and snow\\nYear: 2002\\n\\nAbstract: Predictions of climate change typically use a GCM linked to a land surface model. Land surface models, e.g. Biosphere-Atmosphere Transfer Scheme (BATS), estimate the albedo of trees over snow roughly with the parameters of roughness length, z0, and snow depth, d. Based on their work, we further consider the difference in directional-to-hemisphere albedo for different solar zenith angle (SZA), and leaf area index (LAI) dependence. In order to keep the basic feature of the BATS model and to add these two new features, we simplified the geometric optical and radiative transfer (GORT) hybrid model of Li, et al. [1995] to reach this purpose. This model can be rather simple to retrieve the albedo of remote sensing pixel. It can be a strong tool to understand the climate system.\",\n \"Title: Information content of multi-angular remote sensing data\\nYear: 2002\\n\\nAbstract: In this paper, we take the kernel-driven model as an example, focus on the information contents definition and calculation of multi-angular remote sensing (MARS) data. We study four methods to measure the information content of MARS data: Fisher statistic, information entropy, determinant and sum of the diagonal elements of the information matrix, how to use the Fisher statistic theory and information entropy to measure the information contents of MARS data, to calculate the information contents of the dataset on the three unknowns for different subset of the data. The analyses show that information entropy is a good tool for measuring information content of MARS data.\",\n \"Title: Analyses Of The Relationship Between Atmospheric Temperature Structure And Eofs\\nYear: 2003\\n\\nAbstract: EOF (Empirical Orthogonal Function) technique is usually used in thermal remote sensing in order to reduce the number of the parameters to be inversed. Few researchers put emphases on the physical meaning of the eigenvectors. Our study shows that different eigenvector corresponds with different atmospheric layer. It is necessary to study the physical meaning of the eigenvectors in remote sensing inversion, especially when we put emphases on one or some original unknown parameter(s), which is a common need in remote sensing inversion. First, one EOF choice scheme is proposed in our paper. It not only satisfies the need of whole explained variance but also considers the partial variance related with the parameter we are interested in. The inversion result shows that the scheme is useable to the special unknown parameters. At last, the physical meanings of EOFs have been discussed based on the large sample.\",\n \"Title: Atmospheric correction for AMTIS single-channel multi-angular thermal-infrared imagery\\nYear: 2003\\n\\nAbstract: This paper presents the atmospheric correction algorithm for the TIR band of Airborne Multi-angle TIR/VNIR Imaging System (AMTIS) assumed that no atmospheric profile is available. Under the assumption that the surface emissivity is isotropic, two atmospheric parameters are needed to remove the atmospheric effect: the water vapor content (W) and the effective mean atmosphere temperature (T a). T a can be estimated from the muti-angular observations of the pixel with \\\"minimum standard deviation\\\" of brightness temperatures. After T a is known, W can be retrieved from the pixels with multi-angular observations under the assumption of isotropic emissivity and horizontal uniform atmosphere. Then the atmospheric effect can be removed after the two atmospheric parameters are known. Through the sensitivity analysis of the algorithm to emissivity and transmittance, it can be found that W is very sensitive to the error of emissivity. However, it can also be estimated using the pixel with known surface temperature and emissivity measured synchronously.\",\n \"Title: Leaf Area Index Inversion Using Multiangular And Multispectral Data Sets\\nYear: 2003\\n\\nAbstract: Leaf area index (LAI) is an important parameter for describing vegetation canopy structure in the terrestrial ecosystem. LAI is closely related to plant transpiration, sunlight intercept, photosynthesis and Net Primary Productivity. Multiangular remote sensing is capable of providing more three-dimension information of vegetation, and it is powerful in solving the problem of the same object with different spectrum or vice versa. As a result, multiangular remote sensing and Bidirectional Reflectance Distribution Function (BRDF) model based inversion may be more suitable for Leaf Area index (LAI) retrieval over row crop canopies. However, it's still difficult to get LAI without enough a priori knowledge due to the underdetermined problems in inversion. We use the multispectral information to get the a priori estimation of LAI, and then perform BRDF model inversion. Different from the general one channel based BRDF model inversion methods, our new methods use the muiltiangular and multispectral data sets together to increase the available information in inversion, i.e., it is a synthetic method. From the inversion results we found that the new synthetic method is more effective in LAI inversion.\",\n \"Title: An Iterative Temperature Inversion Method For Nonisothermal Land Surfaces\\nYear: 2003\\n\\nAbstract: We propose an iterative multistage inversion (IMI) algorithm to retrieve the land surface component temperatures for nonisothermal vegetation canopy. Our algorithm is based on a thermal emission model that can simulate the directional effects from the nonisothermal surfaces. Our IMI algorithm just inverts the most uncertain and most sensitive parameters at each step using the most sensitive observation samples, and then adjusts the initial values based on the retrieval results. This inversion process is repeated until convergence condition is satisfied. Compared with the inversion method that try to invert all of the parameters at the same time, the IMI algorithm tends to give more accurate mean values for the parameters and is more stable when the noise level is relative low.\",\n \"Title: Retrieval Of Aerosol Optical Depth And Single Scattering Albedo From Amtis Imagery\\nYear: 2003\\n\\nAbstract: Airborne Multi-angle TIR/VNIR Imaging System (AMTIS) that sample the surface at a number of view angles offer the potential of retrieval of atmospheric aerosol properties, land surface bidirectional reflectance etc. This paper presents the retrieval algorithm of aerosol optical depth and single scattering albedo from visual and near-infrared bands of AMTIS based on a simplified path radiance model. Atmospheric parameters such as molecule scattering and absorption are calculated using MODTRAN4. Under the assumption that the aerosol optical depth above the sensor is not affected by the surface, the aerosol optical depth above the sensor (4.2Km) is also calculated using MODTRAN4. The path radiance is divided into two components: the singly scattered radiance and multiple-scattering radiance. The AMTIS images acquired on Apr. 11, 2001 in the Shunyi experiment are used in the retrieval. The algorithm performs best over the dark surfaces, such as water. The retrieved aerosol optical depth is close to the result from the synchronous Sun photometer data with an error about 0.05similar to0.1. Retrieved single scattering albedo is very close to that of the continental aerosol model of 6S.\",\n \"Title: The maximum entropy algorithm for the determination of the Tikhonov regularization parameter in quantitative remote sensing inversion\\nYear: 2003\\n\\nAbstract: Remote sensing inversion problem is always ill-posed. However, regularization aims at turning the ill-posed problems into certainty. In this paper, taking the linear kernel-driven model as an example, we put forward the maximum entropy algorithm based on information theory to determine the Tikhonov regularization parameter. Then, analyse and compare it with other mature methods. Result shows that the maximum entropy algorithm has advantages when the variance of the observations' noise is small or uncertainty of the prior knowledge is not too large.\",\n \"Title: Atmospheric correction for AMTIS VIS/NIR bands imagery based on BRDF loop and MODTRAN4\\nYear: 2003\\n\\nAbstract: This paper describes the atmospheric correction algorithm for the Airborne Multi-angle TIR/VNIR Imaging System (AMTIS) in VIS/NIR bands. The method is named as a BRDF loop based algorithm. Under the assumption of that the ground cover is non-Lambertian, MODTRAN4 is used to calculate the atmosphere parameters, and the parameters used to decouple the multi-bouncing effect such as direct-hemisphere reflectance and hemisphere-direct reflectance are estimated in the loop correction process. The BRDF model used to calculate albedo is the kernel-driven model. To accelerate the atmospheric correction, all the atmospheric parameters used in this algorithm are pre-computed used MODTRAN4.1 and saved in the look-up table. A prior knowledge is used in the inversion of kernel-driven model when the multi-angle sampling is not enough. The atmospheric correction result is validated using the synchronous ground measurements. From the comparison with the general Lambert assumption based method, it is found that our BRDF loop based method can partly remove the atmospheric smoothing effect.\",\n \"Title: Study on energy balance over different surfaces\\nYear: 2003\\n\\nAbstract: Eddy covariance and Bowen ratio measurements were carried out over different surfaces, and used to characterize the daily variation of energy fluxes and energy balance under different weather condition. These will be used to identify the phenomena to be addressed in future modeling works. Results show that (1) The diurnal variation characteristics of the fluxes were different over different surfaces, especially the latent heat flux, (2) The energy imbalance persisted in different surfaces with an average about 20%; the energy balance closure was better in the afternoon than in the morning averagely, possibly suggesting the underestimation of storage terms, which are usually larger in the morning.\",\n \"Title: Validation Of Modis Albedo Product By Using Field Measurements And Airborne Multi-Angular Remote Sensing Observations\\nYear: 2003\\n\\nAbstract: dAlbedo is a key parameter in monitoring the energy exchanges between the solar radiations and the land,surfaces. The MODIS team generates the albedo products every 16 days. The products need to be validated by ground truths under different environmental conditions. In this study, we developed a 3-step validation procedure. The Ambrals (Algorithm for Modeling Bidirectional Reflectance Anisotropies of the Land Surface) model inversion was used to retrieve the albedo from the measured BRDF data over the winter wheat fields at the point/plot scale. And then, as our second step, the albedo values from the Airborne Multiangular Thermal-infrared Imaging System (AMTIS) over the same target area were estimated and validated using the ground point measurements. Finally, the retrieved albedo from airborne data were aggregated and compared with the MODIS albedo products. Our validation procedure has demonstrated a practical method to validate that albedo from spacebrone remotely sensed data (e.g., MODIS). The validation results show that the MODIS albedo products are reasonably good.\",\n \"Title: The construction of J2EE-based Spectrum Knowledge Base System for Typical Object in China\\nYear: 2003\\n\\nAbstract: The Spectrum Knowledge Base System (SKBS) for Typical Object in China, built up by taking advantage of J2EE technology, is capable of providing the functionalities in spectrum analysis, query and comparison. More importantly, the spectrum scale effect, especially the scale extension, can be achieved in SKBS, which is based on the model-driven theory with the support of the prior knowledge.\",\n \"Title: Practice of quantitative remote sensing model library based on COM technique\\nYear: 2003\\n\\nAbstract: With the development of remote sensing, new models are available continuously. In order to extend the practicability of the model library, the authors introduce component object model (COM) technique. COM is a software architecture that allows the components made by different software vendors to be combined into a variety of applications. Remote sensing model library is composed of three parts, common objects, model objects and accessorial objects. Common objects include input/output procedure, solar angle calculating procedure in bi-directional reflectance, and metadata about all the models. Model objects include the models contributing to quantitative remote sensing applications, which comprise system models, simulant models and application models. Accessorial objects include prior knowledge, measurement data and image data. In the article, the executable project is validated with an instance in the end. The spectrum of typical land surface observed in nadir viewing direction is simulated in pixel scale. In this process, crop model, PROSPECT model and SAIL model are used to calculate the spectrum character of the pixel. Crop model is used to simulate leaf area index, and PROSPECT model is to simulate reflectance and transmission of leaves. The final result is calculated with SAIL model. We simulated the spectrum of winter wheat in given growing season. In the work, each model and each common object are designed to be components. The model library based on COM technique adapts to the progress and is propitious to be expanded and modified.\",\n \"Title: Using Path Analysis To Study Correlation And Causation In Remote Sensing Inversion\\nYear: 2003\\n\\nAbstract: One problem in quantitative remote sensing inversion is the correlations between variables. Path analysis is a statistical technique that differentiates between correlation and causation, features multiple linear regressions, and generates path coefficients. In this paper, path analysis was applied to study the correlations and causations of two cases in remote sensing reversion. One is the retrieval of land surface temperature, and another is to explain the results of land surface moisture estimation. We found that path analysis can be used to study the direct effect and the indirect effects of a variable in remote sensing inversion, and gave a better explanation of the results of multiple linear regression analysis.\",\n \"Title: Using the NDVI Contribution Ratio at Different Growth Stages to Estimate Winter Wheat Yield\\nYear: 2003\\n\\nAbstract: This paper mainly proposed using multi-temporal spectral data with given weight to estimate yield using contribution ratios of different stages to improve yield estimation, then use stepwise regression to build models for yield estimation. The contribution ratio is calculated by principal component analysis respectively. Result show that this methodology reflects the crop growth status, physiological characters at different stages, and improves the accuracy obviously.\",\n \"Title: An Approach On Lai Assimilation Between Field Measurement And Crop Model Simulation\\nYear: 2003\\n\\nAbstract: LAI (Leaf Area Index) is an important parameter for plant growth status detecting. The traditional method to measure leaves' area in field is time and labor consuming. In some remote sensing applications, LAI might be needed more intensively such as daily and weekly. Crop simulation models can be effective tools for simulating LAI, crop and soil water statuses, crop growth and development parameters at the daily step.Ground LAI measurements for winter wheat were carried out in several fields of Shunyi county, Beijing, China at several days' interval during the crop growth season. The CERES-wheat model is run under local soil, weather and management conditions of a field site to simulate daily LAI values. The simulated LAI corresponded comparatively well with the measured ones at the early stage. The results suggested that the technique might be promising for estimating LAI, this make it possible to develop an approach to assimilate LAI of winter wheat between ground measurements and CERES-wheat simulation.\",\n \"Title: Class-Based Kernels Selection For Albedo Inversion By Kernel-Driven Brdf Model\\nYear: 2003\\n\\nAbstract: The kernels are always pre-determined in current kernel-driven model application, but it seems to have a bit disadvantages to the requirement of more accurate remote sensing because it used one kernel combination for all land cover types' inversion. In this paper, we used the 28 different multi-angular data sets, which represent major types of land cover, to find out the relations of different kernels' selection with land cover types firstly. The kernels combinations in the models we compared are volume kernels of Ross-Thick, Ross-Thin and geometric optical kernels of Li-Transit, Li-SparseR and Li-Dense. Then, and the airborne multi-angle TIR/VNIR image system (AMTIS) data set, which was got at Shunyi county of Beijing, China in April 2002, was used to inverse. The inversion results of pre-determined kernels selection and class-based kernels selection were compared, respectively.\",\n \"Title: Correlation Analysis Between Hyperspectral Feature And Foliage Water Content In The Growth Period Of Winter Wheat\\nYear: 2003\\n\\nAbstract: At XiaoTangShan Precision Agriculture Experiment Base, suburban of Beijing city, we obtained the hyperspectral data of wheat canopy by field measurement and synchronal relative foliage water content (RFWC) at lab, according to the different growth stage of wheat, in the spring of 2002. In this paper, we extracted spectral feature parameters firstly. Then, the correlation analysis between the spectral features parameters and RFWC was made. two spectral feature parameters, which have good relativity to foliage water content, to make linear regression models between RFWC and spectral feature parameter according to the growth stages of wheat.\",\n \"Title: Monitoring the seasonal bare soil areas in Beijing using multi-temporal TM images\\nYear: 2004\\n\\nAbstract: Recently, there were many strong sandstorms occurred in North China, which became a severely economical, social and environmental problem, especially for Beijing City. The bare soil is an important source of sandstorm, and the croplands naked in winter in 55 counties around Beijing City became the main source of the sandstorm. It is very important to monitor the seasonal bare soil areas using remote sensing data. The multitemporal TM images of Beijing area in May 16, 1997, April 7, 2003, May 25, 2003, October 24, 2003 and January 28, 2004 were selected. Firstly, the smoothing filter-based intensity modulation (SFIM) completed the image fusion. Secondly, the multistage classification approach was adopted. The multisource data, such as DEM, NDVI, bare soil index (BI), shadow index (SI), were integrated and applied in classification, and the seasonal bare soil areas, such as wasteland, cropland, were successfully extracted. Thirdly, the seasonal and inter-annual dynamic changes of the bare soil areas were also analyzed.\",\n \"Title: A Framework for Consistent Estimation of Leaf Area Index, Fraction of Absorbed Photosynthetically Active Radiation, and Surface Albedo from MODIS Time-Series Data\\nYear: 2015\\n\\nAbstract: Currently available land-surface parameter products are generated using parameter-specific algorithms from various satellite data and contain several inconsistencies. This paper developed a new data assimilation framework for consistent estimation of multiple land-surface parameters from time-series MODerate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. If the reflectance data showed snow-free areas, an ensemble Kalman filter (EnKF) technique was used to estimate leaf area index (LAI) for a two-layer canopy reflectance model (ACRM) by combining predictions from a phenology model and the MODIS surface reflectance data. The estimated LAI values were then input into the ACRM to calculate the surface albedo and the fraction of absorbed photosynthetically active radiation (FAPAR). For snow-covered areas, the surface albedo was calculated as the underlying vegetation canopy albedo plus the weighted distance between the underlying vegetation canopy albedo and the albedo over deep snow. The LAI/FAPAR and surface albedo values estimated using this framework were compared with MODIS collection 5 eight-day 1-km LAI/FAPAR products (MOD15A2) and 500-m surface albedo product (MCD43A3), and GEOV1 LAI/FAPAR products at 1/112° spatial resolution and a ten-day frequency, respectively, and validated by ground measurement data from several sites with different vegetation types. The results demonstrate that this new data assimilation framework can estimate temporally complete land-surface parameter profiles from MODIS time-series reflectance data even if some of the reflectance data are contaminated by residual cloud or are missing and that the retrieved LAI, FAPAR, and surface albedo values are physically consistent. The root mean square errors of the retrieved LAI, FAPAR, and surface albedo against ground measurements are 0.5791, 0.0453, and 0.0190, respectively.\",\n \"Title: The exploring research of a geometric optical canopy reflectance model (GOMS) for retrieving leaf area index directly\\nYear: 2014\\n\\nAbstract: Forest canopy leaf area index (LAI) is an important biological parameter and an evaluation index of the vegetation canopy. It is difficult to get LAI through direct inversion using Li-Strahler geometric-optical model (GOMS)[1,2]. In this paper, LAI is introduced into the GOMS model as an independent variable to substitute other canopy structure parameters. The verification results well demonstrated the accuracy of the modified GOMS model.\",\n \"Title: Direct validation of MODIS spectral Abledo product with field measurement\\nYear: 2014\\n\\nAbstract: Land surface albedo is a key input parameter required in the current general circulation models (GCMs). The accurate validation of albedo products is very important for use in various applications by the scientific community. The most common validation methods compare motely sensed albedo products directly with ground-based observed broadband albedo values without considering the band width inconsistency and the narrow-to-broad band transformation error of these products. Unlike previous validation approaches, we propose a spectral albedo direct validation method. By applying the novel instrument of multi-band albedometer, it is possible to obtain MODIS visible and near-infrared bands albedo measurements. The in-field measured data combined with a 16-day interval is compared directly with MODIS narrow band albedo products. The results indicate that the multi-band albedometer measurement and the MODIS narrow band white and black sky albedo has a good consistency. It is an efficient way to get rid of the errors induced by the band conversion and is a labor-saving technique of making possible time series measurements.\",\n \"Title: Modeling MODIS NBAR time series of vegetated surfaces and its use in LAI recursive estimation\\nYear: 2014\\n\\nAbstract: The inconsistent data quality of remote sensing observation, which is mainly caused by atmospheric conditions, presents problems in the application of these data. For the land cover types that cycle yearly, the variations in surface reflectance usually have temporal periodic characteristics. In this study, we modeled the temporal feature of Moderate-Resolution Imaging Spectroradiometer (MODIS) Nadir BRDF-adjusted reflectance (NBAR) time series data of the typical vegetated area using the season-trend statistical method. The fitting values of season-trend model were applied to the recursive estimation of leaf area index (LAI) time series based on nonlinear autoregressive exogenous (NARX) neural network. The results of MODIS NBAR modeling indicate that the season-trend method is effective to model the NBAR time series of the vegetation surface. The NARX neural network works well using the improved NBAR time series as input, and the estimated LAI time series is more continuous than the MODIS LAI.\",\n \"Title: Quantitative remote sensing research on the vegetation 3-D visual simulation based on object oriented technique\\nYear: 2003\\n\\nAbstract: In the field of remote sensing, it is important to understand interaction between light and vegetation. The interrelation of them has been addressed in many works, and many different radiant models of vegetation have been proposed, such as: geometrical optical models, turbid medium models, hybrid models and computer simulation models. With developing of quantitative remote sensing research, computer simulation models, for example, Monte Carlo simulation model and Radiosity show their importance in analyzing the experimental data. In order to continue calculating the reflectivity from the vegetation by using a computer simulation model, it is essential to build the 3D structure of the vegetation. Therefore, many 3D structure data and optical parameters about the real winter wheat were measured firstly, i.e. height of stem, positions and sizes of the leaves, distributions on the field of wheat. Because these data are numerous and discrete, it is very difficult to simulate the virtual scene with them directly. To cope with it, we arranged all data and parameters in several layers based on the object oriented technique. Moreover, in order to simplify and deduce the structural variables that will be applied to build the 3D visual winter wheat model, we analyzed experimental data statistically in the process of realistic structural model. Several geometric and logical relations about structural variables were developed subsequently, and some variables varying with season were summarized to get the simple regulation with the purpose of simulating growing process of the winter wheat. The extended Lindenmayer system (L-system) method is then used to simulate the virtual scene of winter wheat by giving a few structural variables simplified before. Once the simulation is correct, scattering and reflectance from the 3D structural scene can be calculated using the Monte Carlo simulation model or Radiosity and so on. Our results show that (a) our lighting simulation system efficiently provides the required information at the desired level of accuracy, and (b) the plant growth model is extremely well calibrated against real plants. Furthermore, the method and the relations developed in this paper can be used in other subjects, such as computer graphics.\",\n \"Title: MLAOS: a multi-point linear array of optical sensors for coniferous foliage clumping index measurement.\\nYear: 2014\\n\\nAbstract: The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8-10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy.\",\n \"Title: Improving Space-Time Forest Canopy Lai Simulation By Fusing Forest Growth Model (3-Pg) With Remote Sensing Data\\nYear: 2015\\n\\nAbstract: Leaf area index (LAI) is an important biophysical variable indicating forest growth. A major challenge is to improve the LAI estimates for large forest-covered areas. One way to obtain LAI value is using current LAI products. Current LAI products contain many uncertainties and need improvement. This paper aims to improve forest LAI estimates by combining satellite reflectance derived LAI with forest growth model (physiological principals predicting growth, 3-PG) estimates of LAI. 3-PG can give an accurate estimation of forest inter-annual growing trend, while remote sensing data can provide long time series observation of seasonal variations of forest phenology. We applied this method to Chinese fir forest in China, where the detailed data are available. The combined results were more accurate than either the satellite or the 3-PG estimates. We conclude that we can improve the space-time forest canopy LAI estimates by combining forest growth model with satellite imagery.\",\n \"Title: Long-Time-Series Global Land Surface Satellite Leaf Area Index Product Derived From MODIS and AVHRR Surface Reflectance.\\nYear: 2016\\n\\nAbstract: Leaf area index (LAI) is an important vegetation biophysical variable and has been widely used for crop growth monitoring and yield estimation, land-surface process simulation, and global change studies. Several LAI products currently exist, but most have limited temporal coverage. A long-term high-quality global LAI product is required for greatly expanded application of LAI data. In this paper, ...\",\n \"Title: Bias Analysis In Validation Of Modis Lai Product: A Case Study In Cropland Of Huailai, Northern China\\nYear: 2016\\n\\nAbstract: In the validation of MODIS LAI product, much attention has been paid to directly compare the product data and the reference values, few efforts have been made to analyze the bias of validation result comprehensively. In this paper, based on the evaluation of MODIS LAI product, we further divide the bias into three aspects: algorithm, reflectance data and clumping effect. Moreover, the individual influence on the total bias is quantified. The results of assessment indicate MODIS LAI product has an obvious underestimate, as much as 34.14% in this area compared with reference LAI. Individual influence on the total deviation of each bias is 57.50%, 28.33% and 14.17%, respectively.\",\n \"Title: Multiscale Estimation of Leaf Area Index from Satellite Observations Based on an Ensemble Multiscale Filter.\\nYear: 2016\\n\\nAbstract: Currently, multiple leaf area index (LAI) products retrieved from remote sensing data are widely used in crop growth monitoring, land-surface process simulation and studies of climate change. However, most LAI products are only retrieved from individual satellite observations, which may result in spatial-temporal discontinuities and low accuracy in these products. In this paper, a new method was developed to simultaneously retrieve multiscale LAI data from satellite observations with different spatial resolutions based on an ensemble multiscale filter (EnMsF). The LAI average values corresponding to the date of satellite observations were calculated from the multi-year Moderate Resolution Imaging Spectroradiometer (MODIS) LAI product and were used as a priori knowledge for LAI in order to construct an initial ensemble multiscale tree (EnMsT). Satellite observations obtained at different spatial resolutions were then applied to update the LAI values at each node of the EnMsT using a two-sweep filtering procedure. Next, the retrieved LAI values at the finest scale were used as a priori knowledge for LAI for the new round of construction and updating of the EnMsT, until the sum of the difference of LAI values at each node of the EnMsT between two adjacent updates is less than a given threshold. The method was tested using Thematic Mapper (TM) or Enhanced Thematic Mapper Plus (ETM+) surface reflectance data and MODIS surface reflectance data from five sites that have different vegetation types. The results demonstrate that the retrieved LAI values for each spatial resolution were in good agreement with the aggregated LAI reference map values for the corresponding spatial resolution. The retrieved LAI values at the coarsest scale provided better accuracy with the aggregated LAI reference map values (root mean square error (RMSE) = 0.45) compared with that obtained from the MODIS LAI values (RMSE = 1.30).\",\n \"Title: Bayesian Method for Building Frequent Landsat-Like NDVI Datasets by Integrating MODIS and Landsat NDVI.\\nYear: 2016\\n\\nAbstract: Studies related to vegetation dynamics in heterogeneous landscapes often require Normalized Difference Vegetation Index (NDVI) datasets with both high spatial resolution and frequent coverage, which cannot be satisfied by a single sensor due to technical limitations. In this study, we propose a new method called NDVI-Bayesian Spatiotemporal Fusion Model (NDVI-BSFM) for accurately and effectively building frequent high spatial resolution Landsat-like NDVI datasets by integrating Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat NDVI. Experimental comparisons with the results obtained using other popular methods (i.e., the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM), and the Flexible Spatiotemporal DAta Fusion (FSDAF) method) showed that our proposed method has the following advantages: (1) it can obtain more accurate estimates; (2) it can retain more spatial detail; (3) its prediction accuracy is less dependent on the quality of the MODIS NDVI on the specific prediction date; and (4) it produces smoother NDVI time series profiles. All of these advantages demonstrate the strengths and the robustness of the proposed NDVI-BSFM in providing reliable high spatial and temporal resolution NDVI datasets to support other land surface process studies.\",\n \"Title: Comparison and Evaluation of Three Methods for Estimating Forest above Ground Biomass Using TM and GLAS Data.\\nYear: 2017\\n\\nAbstract: Medium spatial resolution biomass is a crucial link from the plot to regional and global scales. Although remote-sensing data-based methods have become a primary approach in estimating forest above ground biomass (AGB), many difficulties remain in data resources and prediction approaches. Each kind of sensor type and prediction method has its own merits and limitations. To select the proper estimation algorithm and remote-sensing data source, several forest AGB models were developed using different remote-sensing data sources (Geoscience Laser Altimeter System (GLAS) data and Thematic Mapper (TM) data) and 108 field measurements. Three modeling methods (stepwise regression (SR), support vector regression (SVR) and random forest (RF)) were used to estimate forest AGB over the Daxing'anling Mountains in northeastern China. The results of models using different datasets and three approaches were compared. The random forest AGB model using Landsat5/TM as input data was shown the acceptable modeling accuracy (R-2 = 0.95 RMSE = 17.73 Mg/ha) and it was also shown to estimate AGB reliably by cross validation (R-2 = 0.71 RMSE = 39.60 Mg/ha). The results also indicated that adding GLAS data significantly improved AGB predictions for the SVR and SR AGB models. In the case of the RF AGB models, including GLAS data no longer led to significant improvement. Finally, a forest biomass map with spatial resolution of 30 m over the Daxing'anling Mountains was generated using the obtained optimal model.\",\n \"Title: Extended Data-Based Mechanistic Method for Improving Leaf Area Index Time Series Estimation with Satellite Data.\\nYear: 2017\\n\\nAbstract: Leaf area index (LAI) is one of the key parameters in crop growth monitoring and global change studies. Multiple LAI products have been generated from satellite observations, many of which suffer from data discontinuities due to persistent cloud contamination and retrieval algorithm inaccuracies. This study proposes an extended data-based mechanistic method (EDBM) for estimating LAI time series from Moderate Resolution Imaging Spectroradiometer (MODIS) data. The data-based mechanistic model is universalized to supply the LAI background information, and then the vegetation canopy radiative-transfer model (PROSAIL) is coupled to calculate reflectances with the same observation geometry as MODIS reflectance data. The ensemble Kalman filter (ENKF) is introduced to improve LAI estimation based on the difference between simulated and observed reflectances. Field measurements from seven Benchmark Land Multisite Analysis and Intercomparison of Products (BELMANIP) sites and reference maps from the Imagine-S project La Albufera, Spain site were used to validate the model. The results demonstrate that when compared with field measurements, the LAI time-series estimates obtained using this approach were superior to those obtained with the MODIS 500 m resolution LAI product. The root mean square errors (RMSE) of the MODIS LAI product and of the LAI estimated with the proposed method were 1.26 and 0.5, respectively. When compared with reference LAI maps, the results indicate that the estimated LAI is spatially and temporally consistent with LAI reference maps. The average differences between EDBM and the LAI reference map on the selected four days was 0.32.\",\n \"Title: Detecting Forest Disturbance in Northeast China from GLASS LAI Time Series Data Using a Dynamic Model.\\nYear: 2017\\n\\nAbstract: Large-scale forest disturbance often leads to changes in forest cover and structure, which imposes a great uncertainty in the estimation of the forest carbon cycle and biomass and affects other applications. In northeastern China, the Daxinganling region has abundant forest resources, where the forest coverage is about 30%. The Global LAnd Surface Satellite (GLASS) leaf area index (LAI) time series data provide important information to monitor the possible change of forests. In this study, we developed a new method to detect forest disturbances using GLASS LAI data over the Daxinganling region of Northeast China. As a dynamic model, the season-trend model has a higher sensitivity toward a seasonal change in LAI. Based on the accumulation of multi-year GLASS LAI products from 1997 to 2002, the dynamic model of LAI time series for each pixel is established first. The time-stepping modeling (TSM) process was designed by using the season-trend method, and sequential tests for detecting disturbances from a time series of pixels. Significant changes in the model parameters were captured as disturbance signals. Then, the near-infrared and shortwave-infrared bands of Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance are used as auxiliary information to distinguish the types of forest disturbances. Here, the algorithm led to the detection of two different types of disturbances: fire and other (e.g., insect, drought, deforestation). In this study, we took the forest region as the study area, used the 8-day composite GLASS LAI data at 1000-m spatial resolution to identify each pixel as a fire disturbance, other disturbance, or non-disturbance. Validation was performed using reference burned area data derived from Landsat 30 m imagery. Results were also compared with the MCD64 product. The validation results were based on confusion matrices showing the overall accuracy (OA) exceeded 92% for our method and the MCD64 product. Statistical tests identified that TSM's product accuracy is higher than that of MCD64. This study demonstrated that the TSM algorithm using a season-trend model provides a simple and automated approach to identify and map forest disturbance.\",\n \"Title: Impacts of Leaf Age on Canopy Spectral Signature Variation in Evergreen Chinese Fir Forests.\\nYear: 2018\\n\\nAbstract: Significant gaps exist in our knowledge of the impact of leaf aging on canopy signal variability, which limits our understanding of vegetation status based on remotely sensed data. To understand the effects of leaf aging at the leaf and canopy scales, a combination of field, remote-sensing and physical modeling techniques was adopted to assess the canopy spectral signals of evergreen Cunninghamia forests. We observed an approximately 10% increase in Near-Infrared (NIR) reflectance for new leaves and a 35% increase in NIR transmittance for mature leaves from May to October. When variations in leaf optical properties (LOPs) of only mature leaves, or both new and mature leaves were considered, the Geometric Optical and Radiative Transfer (GORT) model-simulated canopy reflectance trajectory was more consistent with Landsat observations (R-2 increased from 0.37 to 0.82 similar to 0.89 for NIR reflectance, and from 0.35 to 0.67 similar to 0.88 for EVI2, with a small RMSE (0.01 to 0.02)). This study highlights the importance of leaf age on leaf spectral signatures, and provides evidence of age-dependent LOPs that have important impacts on canopy reflectance in the NIR band and EVI2, which are used to monitor canopy dynamics and productivity, with important implications for RS and forest ecosystem ecology.\",\n \"Title: From Geometric-Optical Remote Sensing Modeling to Quantitative Remote Sensing Science - In Memory of Academician Xiaowen Li.\\nYear: 2018\\n\\nAbstract: The academician Xiaowen Li devoted much of his life to pursuing fundamental research in remote sensing. A pioneer in the geometric-optical modeling of vegetation canopies, his work is held in high regard by the international remote sensing community. He codeveloped the Li-Strahler geometric-optic model, and this paper was selected by a member of the International Society for Optical Engineering (SPIE) milestone series. As a chief scientist, Xiaowen Li led a scientific team that made outstanding advances in bidirectional reflectance distribution modeling, directional thermal emission modeling, comprehensive experiments, and the understanding of spatial and temporal scale effects in remote sensing information, and of quantitative inversions utilizing remote sensing data. In addition to his broad research activities, he was noted for his humility and his dedication in making science more accessible for the general public. Here, the life and academic contributions of Xiaowen Li to the field of quantitative remote sensing science are briefly reviewed.\",\n \"Title: The 3d Simulation Database Setup For The Realistic Scene Of The Typical Crops\\nYear: 2004\\n\\nAbstract: Computer simulation is one of the vegetation canopy reflectance modeling method, which can realistically simulate the radiation interaction process within vegetation canopies and their dependence on various canopy structural parameters. In this paper, we mainly use the computer simulation methods, combined computer graphics with radiosity equation to simulate the radiative transfer process of the scene in both visible and near-infrared regions. There are five components in our 3D model: computer graphics technique to generate 3D objects; radiosity equation to describe the radiation exchange among the 3D objects, graphics based methods to compute view factors; radiosity computation and 3D image display of the objects; lastly introduced our 3D simulation database built up to put all information in it, such as simulated vegetation canopy's 3D structure files and the spectral data information of the vegetation and scene, in order to convenience users to query and retrieve correlating spectral information.\",\n \"Title: A Prior Knowledge-Based Method to Derivate High-Resolution Leaf Area Index Maps with Limited Field Measurements.\\nYear: 2017\\n\\nAbstract: High-resolution leaf area index (LAI) maps from remote sensing data largely depend on empirical models, which link field LAI measurements to the vegetation index. The existing empirical methods often require the field measurements to be sufficient for constructing a reliable model. However, in many regions of the world, there are limited field measurements available. This paper presents a prior knowledge-based (PKB) method to derivate LAI with limited field measurements, in an effort to improve the accuracy of empirical model. Based on the assumption that the experimental sites with the same vegetation type can be represented by similar models, a priori knowledge for crops was extracted from the published models in various cropland sites. The knowledge, composed of an initial guess of each model parameter with the associated uncertainty, was then combined with the local field measurements to determine a semi-empirical model using the Bayesian inversion method. The proposed method was evaluated at a cropland site in the Huailai region of Hebei Province, China. Compared with the regression method, the proposed PKB method can effectively improve the accuracy of empirical model and LAI estimation, when the field measurements were limited. The results demonstrate that a priori knowledge extracted from the universal sites can provide important auxiliary information to improve the representativeness of the empirical model in a given study area.\",\n \"Title: Design of a Novel Spectral Albedometer for Validating the MODerate Resolution Imaging Spectroradiometer Spectral Albedo Product.\\nYear: 2018\\n\\nAbstract: Land surface shortwave broadband albedo is a key parameter in general circulation models and surface energy budget models. Multispectral satellite data are typically used to generate broadband albedo products in a three-step process: atmospheric correction, for converting the top-of-atmosphere observations to surface directional reflectance; angular modeling, for converting the surface directional reflectance to spectral albedo of each individual band; and finally, narrowband-to-broadband conversion, for transforming the spectral albedos to broadband albedos. Spectroradiometers can be used for validating surface directional reflectance products and pyranometers or broadband albedometers, for validating broadband albedo products, but spectral albedo products are rarely validated using ground measurements. In this study, we designed a new type of albedometer that can measure spectral albedos. It consists of multiple interference filters and a silicon detector, for measuring irradiance from 400-1100 nm. The linearity of the sensors is 99%, and the designed albedometer exhibits consistency up to 0.993, with a widely-used commercial instrument. A field experiment for measuring spectral albedo of grassland using this new albedometer was conducted in Yudaokou, China and the measurements are used for validating the MODerate Resolution Imaging Spectroradiometer (MODIS) spectral albedos. The results show that the biases of the MODIS spectral albedos of the first four bands are -0.0094, 0.0065, 0.0159, and -0.0001, respectively. This new instrument provides an effective technique for validating spectral albedos of any satellite sensor in this spectral range, which is critical for improving satellite broadband albedo products.\",\n \"Title: A Recursive Update Model for Estimating High-Resolution LAI Based on the NARX Neural Network and MODIS Times Series.\\nYear: 2019\\n\\nAbstract: Leaf area index (LAI) remote sensing data products with a high resolution (HR) and long time series are in demand in a wide variety of applications. Compared with long time series LAI products with 1 km resolution, LAI products with high spatial resolution are difficult to acquire because of the lack of remote sensing observations in long-term sequences and the lack of estimation methods applicable to highly variable land-cover types. To address these problems, we proposed a recursive update model to estimate 30 m resolution LAI based on the updated Nonlinear Auto-Regressive with Exogenous Inputs (NARX) neural network and MODIS time series. First, we used a variety of HR satellite remote sensing observations to produce HR datasets for recent years. Historical low spatial resolution MODIS products were employed as background information and used to calculate the initial parameters of the NARX neural network for each pixel. Subsequently, one year's reflectance from the HR dataset was used as the new observation that was input into the NARX model to estimate the HR LAI of that year, and the background and HR data were then used for remodeling to update the NARX model parameters. This procedure was recursively repeated year by year until both MODIS background data and all HR data were involved in the modeling. Finally, we obtained an LAI time series with 30 m resolution. In the cropland study area in Hebei Province, China, the results were compared with LAI measurements from ground sites in 2013 and 2014. A high degree of similarity existed between the results for the two study years (RMSE2013 = 0.288 and RMSE2014 = 0.296). The HR LAI estimates showed favorable spatiotemporal continuity and were in good agreement with the multisample ground survey LAI measurements. The results indicated that for data with a rapid revisit cycle and high spatial resolution, the recursive update model based on the NARX neural network has excellent LAI estimation performance and fairly strong fault-tolerance capability.\",\n \"Title: Evaluating the Spatial Representativeness of the MODerate Resolution Image Spectroradiometer Albedo Product (MCD43) at AmeriFlux Sites.\\nYear: 2019\\n\\nAbstract: Land surface albedo is a key parameter in regulating surface radiation budgets. The gridded remote sensing albedo product often represents information concerning an area larger than the nominal spatial resolution because of the large viewing angles of the observations. It is essential to quantify the spatial representativeness of remote sensing products to better guide the sampling strategy in field experiments and match products from different sources. This study quantifies the spatial representativeness of the MODerate Resolution Image Spectroradiometer (MODIS) (collection V006) 500 m daily albedo product (MCD43A3) using the high-resolution product as intermediate data for different land cover types. A total of 1820 paired high-resolution Landsat Thematic Mapper (TM) and coarse-resolution (MODIS) albedo data from five land cover types were used. The TM albedo data was used as the spatial-complete high resolution data to evaluate the spatial representativeness of the MODIS albedo product. Semivarioagrams were estimated from 30 m Landsat data at different spatial scales. Surface heterogeneity was evaluated with sill value and relative coefficient of variation. The 30 m Landsat albedo data was aggregated to 450 m-1800 m using two different methods and compared with MODIS albedo product. The spatial representativeness of MODIS albedo product was determined according to the surface heterogeneity and the consistency of MODIS data and the aggregated TM value. Results indicated that for evergreen broadleaf forests, deciduous broadleaf forests, open shrub lands, woody savannas and grasslands, the MODIS 500 m daily albedo product represents a spatial scale of approximately 630 m. For mixed forests and croplands, the representative spatial scale was approximately 690 m. The difference obtained was primarily because of the complexity of the landscape structure. For mixed forests and croplands, the structure of the landscape was relatively complex due to the presence of different forest and plant types in the pixel area, whereas the other landscape structures were considerably simpler.\",\n \"Title: Time Series High-Resolution Land Surface Albedo Estimation Based on the Ensemble Kalman Filter Algorithm.\\nYear: 2019\\n\\nAbstract: Continuous, long-term sequence, land surface albedo data have crucial significance for climate simulations and land surface process research. Sensors such as the Moderate-Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer (VIIRS) provide global albedo product data sets with a spatial resolution of 500 m over long time periods. There is demand for new high-resolution albedo data for regional applications. High-resolution observations are often unavailable due to cloud contamination, which makes it difficult to obtain time series albedo estimations. This paper proposes an amalgamation albedo approach to generate daily land surface shortwave albedo with 30 m spatial resolution using Landsat data and the MODIS Bidirectional Reflectance Distribution Functions (BRDF)/Albedo product MCD43A3 (V006). Historical MODIS land surface albedo products were averaged to obtain an albedo estimation background, which was used to construct the albedo dynamic model. The Thematic Mapper (TM) albedo derived via direct estimation approach was then introduced to generate high spatial-temporal resolution albedo data based on the Ensemble Kalman Filter algorithm (EnKF). Estimation results were compared to field observations for cropland, deciduous broadleaf forest, evergreen needleleaf forest, grassland, and evergreen broadleaf forest domains. The results indicated that for all land cover types, the estimated albedos coincided with ground measurements at a root mean squared error (RMSE) of 0.0085-0.0152. The proposed algorithm was then applied to regional time series albedo estimation; the results indicated that it captured spatial and temporal variation patterns for each site. Taken together, our results suggest that the amalgamation albedo approach is a feasible solution to generate albedo data sets with high spatio-temporal resolution.\",\n \"Title: Spectral collocation methods for nonlinear coupled time fractional Nernst–Planck equations in two dimensions and its convergence analysis\\nYear: 2019\\n\\nAbstract: In this paper, a nonlinear coupled time fractional Nernst–Planck equation in two dimensions space is considered. Using properties of the Caputo fractional derivative and Riemann–Liouville fractional integral, the time fractional Nernst–Planck problem is transformed into a Volterra integral model with singular kernel equivalently. We propose a novelty spectral collocation method in time and space with a spectral expansion of Jacobi interpolation polynomial to discretize the model. We also derive the optimal rate of convergence of this method. Numerical results are presented to verify efficiency of collocation methods and spectral accuracy theory.\",\n \"Title: A Novel Semantic Recognition Framework Of Urban Functional Zones Supporting Urban Land Structure Analytics Based On Open-Source Data\\nYear: 2021\\n\\nAbstract: To solve problems related to urban land development, protection, and management, urban planners focus on achieving high precision and currency for fine-grained semantic recognition of urban functional zones (UFZs). The classification of discrete functional zones and qualitative recognition of UFZs have been well studied, but the precise recognition of UFZs with explicit depictions of socioeconomic urban functions has seldom been addressed. Thus, we propose a novel open-source data-guided semantic urban function recognition (OSD-SFR) framework to analyze UFZs and quantitatively link open-source data (OSD) with the Chinese national urban function classification code. The spatial relationship between the combined semantic database and the segmented urban zones data set was measured, graded, and categorized. Kernel density and statistical methods based on a single data source of points-of interest were used for comparative experiments. The results indicate that OSD-SFR yields more fine-grained delineations between urban functions and achieves more accurate recognition. Critical semantic information from different OSD sources is deeply integrated. This study provides a realistic reference, including detailed descriptions of the spatial distribution and morphological structure of UFZs, to support long-term city planning.\",\n \"Title: Identifying Spatial and Temporal Characteristics of Land Surface Albedo Using GF-1 WFV Data\\nYear: 2021\\n\\nAbstract: Land surface albedo (LSA) is an important parameter that affects surface-air interactions and controls the surface radiation energy budget. The spatial and temporal variation characteristics of LSA reflect land surface changes and further influence the local climate. Ganzhou District, which belongs to the middle of the Hexi Corridor, is a typical irrigated agricultural and desert area in Northwest China. The study of the interaction of LSA and the land surface is of great significance for understanding the land surface energy budget and for ground measurements. In this study, high spatial and temporal resolution GF-1 wide field view (WFV) data were used to explore the spatial and temporal variation characteristics of LSA in Ganzhou District. First, the surface albedo of Ganzhou District was estimated by the GF-1 WFV. Then, the estimated results were verified by the surface measured data, and the temporal and spatial variation characteristics of surface albedo from 2014 to 2018 were analyzed. The interaction between albedo and precipitation or temperature was analyzed based on precipitation and temperature data. The results show that the estimation of surface albedo based on GF-1 WFV data was of high accuracy, which can meet the accuracy requirements of spatial and temporal variation characteristic analysis of albedo. There are obvious geographic differences in the spatial distribution of surface albedo in Ganzhou, with the overall distribution characteristics being high in the north and low in the middle. The interannual variation in annual average surface albedo in Ganzhou shows a trend of slow fluctuations and gradual increases. The variation in annual albedo is characterized by \\\"double peaks and a single valley \\\", with the peaks occurring from December to February at the end and beginning of the year, and the valley occurring from June to August. Surface albedo was negatively correlated with precipitation and temperature in most areas of Ganzhou.\",\n \"Title: Land Surface Albedo Estimation With Chinese GF-1 WFV Data in Northwest China\\nYear: 2022\\n\\nAbstract: Land surface albedo (LSA) is one of the driving factors in the energy balance of surface radiation and the interaction between the earth and atmosphere. LSA is an important parameter that is widely used in surface energy balance, medium- and long-term weather forecasting, and global change studies. GF-1 wide field view (WFV) data provide a spatial resolution of 16 m and temporally intensive land surface observations, but efficient algorithm was still lacking for quantitatively land surface parameters estimation. It is essential to improve the data use ability by generating efficient land surface parameter retrieval algorithms. This study proposed an LSA retrieval algorithm by using GF-1 WFV data. Land surface bidirectional reflectance distribution function characteristic parameters were used to represent the non-Lambertian characteristic of land surface. The top of atmosphere (TOA) reflectance is simulated by the 6S radiative transfer model by considering non-Lambertian land surfaces. Linear regression is applied in the TOA reflectance, and LSA is simulated with the surface bidirectional reflectance characteristic parameters to build a lookup table. The proposed algorithm can estimate LSA with high accuracy according to the TOA reflectance without the complex multistep inversion process. The validation results of ground measurements in Northwest China for different land cover types show that the algorithm is effective, and the overall root mean square error was 0.036 when compared with field observation. The algorithm also shows great consistency with Landsat albedo data. The proposed algorithm is of great significance for improving GF data utilization.\",\n \"Title: Compatible L2 norm convergence of variable-step L1 scheme for the time-fractional MBE model with slope selection\\nYear: 2022\\n\\nAbstract: •An L2 norm error estimate is proven under a CSS-consistent time-step condition.•Time-step sizes for convergence, solvability and stability are of the same order.•Our estimate is robust and asymptotically compatible as the order α→1−.•The L1 scheme with an adaptive time-stepping strategy is practically reliable.\",\n \"Title: Two energy stable variable-step L1 schemes for the time-fractional MBE model without slope selection\\nYear: 2023\\n\\nAbstract: A variable-step L1 scheme is proposed for the time-fractional molecular beam epitaxy model without slope selection. By taking advantage of the convex splitting of nonlinear bulk, a sharp L2 norm error estimate is established under a convergence–solvability–stability (CSS) consistent time-step constraint, that is, the maximum step-size limit required for convergence is of the same order to that for solvability and stability (in certain norms) as the small interface parameter ϵ→0+. By using the discrete gradient structure of L1 formula, we build up a discrete variational energy dissipation law, which is asymptotically compatible with the classical energy dissipation law, as the fractional order α→1−. The stability and convergence of the stabilized convex splitting scheme are also investigated. The resulting scheme is shown to unconditionally preserve the variational energy dissipation law by adding a (2−α)-order stabilization term like τn1−α(ϕn−ϕn−1). Numerical experiments are presented to support our theoretical results.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":95,"string":"95"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":254,"string":"254"}}},{"rowIdx":255,"cells":{"question_id":{"kind":"string","value":"Marian K Kazimierczuk"},"question":{"kind":"string","value":"Generate an abstract for the title \"Two-Switch Flyback Pwm Dc-Dc Converter In Continuous-Conduction Mode\" using the following items: 1. Two-switch flyback converter\n2. Clamping diodes\n3. Steady-state analysis\n4. Power loss comparison\n5. Experimental validation"},"answer":{"kind":"string","value":"The two-switch flyback DC-DC converter is an extended version of the conventional single-switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single-switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two-switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed steady-state analysis and design procedure of the diode-clamped two-switch flyback converter operated in continuous-conduction mode (CCM). The power loss in each component of the two-switch flyback converter is compared with those of the single-switch flyback converters with and without RCD clamp, and is presented in a tabular form. The two-switch flyback converter was bread-boarded to validate the theoretical analysis. Experimental results from a 10?V/30?W, 100?kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright (c) 2010 John Wiley & Sons, Ltd."},"correct_answer":{"kind":"string","value":"The two-switch flyback DC-DC converter is an extended version of the conventional single-switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single-switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two-switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed steady-state analysis and design procedure of the diode-clamped two-switch flyback converter operated in continuous-conduction mode (CCM). The power loss in each component of the two-switch flyback converter is compared with those of the single-switch flyback converters with and without RCD clamp, and is presented in a tabular form. The two-switch flyback converter was bread-boarded to validate the theoretical analysis. Experimental results from a 10?V/30?W, 100?kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright (c) 2010 John Wiley & Sons, Ltd."},"documents":{"kind":"list like","value":["Title: Modelling Winding Losses in High-Frequency Power inductors.\nYear: 1995\n\nAbstract: A high-frequency model of iron-powder-core inductors is studied. The skin and proximity effects that cause the winding parasitic resistance to increase with the operating frequency are considered. The inductor self-resonance due to the parasitic capacitances is taken into account as well. The frequency response of the inductor model is compared to that of an experimentally tested iron-powder-core inductor. Expressions giving the ac resistance as a function of the operating frequency are given. These expressions allow for an accurate prediction of the inductor power loss over a wide frequency range. The measured and calculated values of the inductor impedance magnitude and phase, the real and imaginary parts of the inductor impedance, the inductance, and the inductor quality factor are plotted versus frequency and compared. Theoretical results were in good agreement with those experimentally measured. A design procedure for solid wire winding inductors based on the results of the inductor modelling is also given in the paper.","Title: Sample And Hold Effect In Pwm Dc-Dc Converters With Peak Current-Mode Control\nYear: 2004\n\nAbstract: The sample and hold effect, or quasi-digital (discrete) behavior, of constant-frequency peak current-mode control (PCM) in pulse-width modulated DC-DC converters is presented in a manner consistent with the physical behavior of the circuit. This approach developes a transfer function using control theory that captures the quasi-digital behavior encountered when the current control loop is closed in PCM. The new transfer function accurately captures the current loop behavior, leading the way for a complete linear time-invariant system circuit for PWM DC-DC converters. This work improves upon previous derivations by remaining true to the physical behavior of the circuit while resulting in a rational transfer function that can be used in a mutliple loop complete linear system circuit to accurately predict converter behavior due to changes in input voltage, output current, and reference voltage.","Title: Bandwidth of Current Transformers\nYear: 2009\n\nAbstract: Bandwidth is one of the important performance parameters of current transformers. Transformers are required to have adequate bandwidth to regenerate the measured current, apart from uncertainties that are caused by the nonsinusoidal waveforms along with harmonics. An expression for the transresistance of the current transformer in terms of parasitic components is derived. Approximate expressions f...","Title: Voltage-Loop Power-Stage Transfer Functions With MOSFET Delay for Boost PWM Converter Operating in CCM\nYear: 2007\n\nAbstract: Open-loop transfer functions can be used to create closed-loop models of pulsewidth-modulated (PWM) converters. The closed-loop small-signal model can be used to design a controller for the switching converter with well-known linear control theory. The dynamics of the power stage for boost PWM dc-dc converter operating in continuous-conduction mode (CCM) are studied. The transfer functions from ou...","Title: Measurement of open-loop small-signal control-to-output transfer function of a PWM boost converter operated in DCM\nYear: 2002\n\nAbstract: A practical procedure for measuring the control-to-output transfer function of a PWM boost converter operated in discontinuous conduction mode (DCM) is given. It is shown that a simple, low cost measurement setup can be used to test a boost converter and verify a small-signal model of PWM boost converter.The results of this work shows that a frequency-domain description of a PWM dc-dc boost converter can be achieved by using a simple measurement setup. Moreover, the frequency behavior of the model considered here yields accurate results for small-signal, frequency-domain representation of the converter.Therefore, the model can be used to derive the expressions and Bode plots of the control-to-output transfer function. Finally, the proposed method can be utilized in designing an appropriate feedback loop of the converter.","Title: Small-signal duty cycle to inductor current transfer function for boost PWM DC-DC converter in continuous conduction mode\nYear: 2004\n\nAbstract: The small-signal transfer function from duty cycle to inductor current is derived for the boost DC-DC converter operating in continuous conduction mode (CCM). The transfer function is found for two cases, the converter with a resistive load, and with a current sink load. The derivations are performed using an averaged circuit small-signal model of the boost converter for CCM. The transfer function can be used to model the current loop of boost PWM converters with peak current-mode control (PCM).","Title: Analysis and design of class DE amplifier with nonlinear shunt capacitances\nYear: 2009\n\nAbstract: In this paper, equations for waveforms and design relationships are derived for class DE amplifiers with nonlinear shunt capacitances. Using the analytical waveform equations, it is shown that the nonlinearity of the shunt capacitances affects the waveforms only during the dead-time intervals. Additionally, the waveforms with nonlinear and linear shunt capacitances are not very different if class E zero-voltage switching/zero-derivative switching conditions are satisfied. The operation of a class DE amplifier has two dead-time intervals in one period. The switch-voltage waveforms for both dead-time intervals exhibit symmetry. Therefore, the nonlinearity does not have any effect on the series-resonant-circuit elements. As a result, analytical design equations indicate that the series-resonant-circuit elements are independent of the nonlinearity of the shunt capacitances when the supply voltage and the output power are given as design specifications, which is an important result of this paper. The validity of our analysis is confirmed by PSpice simulations and the circuit experiment.","Title: Class-N high-frequency power amplifier\nYear: 2002\n\nAbstract: A new class of high-efficiency amplification is introduced. It based on reducing of time-average dissipated in transistor power instead of state-of-the-art reducing of instantaneous dissipated power. It becomes possible due the influence of capacitances currents that produce a negative collector current swing during a part of ac- period. In this case, along with always-positive collector- emitter voltage, the instant dissipated power also is negative. A high-efficiency BJT power amplifier was simulated in order to demonstrate a new class features.","Title: Design of Class-E Amplifier With MOSFET Linear Gate-to-Drain and Nonlinear Drain-to-Source Capacitances.\nYear: 2011\n\nAbstract: This paper presents expressions for the waveforms and design equations to satisfy the ZVS/ZDS conditions in the class-E power amplifier, taking into account the MOSFET gate-to-drain linear parasitic capacitance and the drain-to-source nonlinear parasitic capacitance. Expressions are given for power output capability and power conversion efficiency. Design examples are presented along with the PSpi...","Title: Experimental Results for the Small-Signal Study of the PWM Boost DC-DC converter with an integral-lead Controller.\nYear: 1995\n\nAbstract: An experimental verification of previously derived small-signal low-frequency open- and closed-loop characteristics and step responses of a voltage-mode-controlled pulse-width-modulated (PWM) boost DC-DC converter is presented. The Bode plots of the voltage transfer function of the control circuit, the converter and the PWM modulator, the open-loop control-to-output and input-to-output transfer functions, the loop gain, and the closed-loop control-to-output and input-to-output transfer functions are measured. The step responses to the changes in the input voltage, the duty cycle, and the reference voltage are measured. The theoretical results were in good agreement with the measured results. The small-signal model of the converter is experimentally verified.","Title: Waveform Equations, Output Power, and Power Conversion Efficiency for Class-E Inverter Outside Nominal Operation\nYear: 2014\n\nAbstract: This paper presents analytical expressions for steady-state waveforms, output power, and power conversion efficiency for the class-E inverter outside the class-E zero-voltage switching and zero-derivative switching conditions. The analytical expressions in this paper include the MOSFET-body-diode effect. By carrying out PSpice simulations and circuit experiments, it is shown that the analytical predictions agree with the simulated and experimental results quantitatively, which indicates the validity of the analytical expressions. Additionally, the switching-pattern distribution maps are also given by using the analytical waveform equations.","Title: Analysis of PWM Z-Source DC-DC Converter in CCM for Steady State.\nYear: 2012\n\nAbstract: Steady-state analysis of pulse-width modulated (PWM) Z-source dc-dc converter operating in continuous conduction mode (CCM) is presented. Voltage and current waveforms, and their corresponding expressions describing the steady-state operation of the PWM Z-source dc-dc converter have been presented. The input-to-output dc voltage transfer functions, both for ideal and non-ideal PWM Z-source dc-dc c...","Title: Single-Loop Current-Mode Control of a PWM Boost DC-to-DC converter with a Non-Symmetric phase Controller.\nYear: 1995\n\nAbstract: An extensive small-signal analysis of a single-loop current-mode control strategy for a pulse-width-modulated (PWM) boost DC-to-DC power converter operating in continuous conduction mode (CCM) is proposed using a new non-symmetric phase controller. To model the boost power stage, a linear circuit model is used which includes all parasitic components such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor ON-resistance, and the diode forward resistance and offset voltage. A boost power stage design example gives component design equations and will serve to illustrate the closed-loop converter design. A design procedure for the new non-symmetric phase controller is presented. Open-loop and closed-loop circuit models and transfer functions are derived for the boost PWM converter and illustrated by Bode plots. An approach is presented for simplifying closed-loop transfer functions, using Euler's identity, into a format which is conducive so modeling in any high level programming language on a personal computer. Bode plots are obtained using a data analysis software package Axum 3.0 which combines a programming language, spread sheet, and publication quality technical graphics. The proposed control scheme directly controls the inductor current and indirectly controls the load current and output voltage. The closed-loop transfer functions of the proposed control scheme do not contain a right-half plane (RHP) zero, in contrast to the closed-loop transfer functions of a single-loop voltage-mode control scheme. The absence of the RHP zero provides better stability by making it easier to obtain large or specified gain and phase margins.","Title: Design Equations For Sub-Optimum Operation Of Class E Amplifier With Nonlinear Shunt Capacitance\nYear: 2004\n\nAbstract: Design equations for satisfying sub-optimum operating conditions of Class E amplifier with a nonlinear shunt capacitance with a grading coefficient of 0.5 at the duty cycle D = 0.5 are derived. By exploiting sub-optimum class E operation, various amplifier parameters such as input voltage, operating frequency, output power, and load resistance can be set as design specifications. An example of a design procedure of the class E amplifier is given. The theoretical results were verified with PSpice simulation.","Title: Open- and Closed-Loop DC and Small-Signal Characteristics of PWM buck-Boost converter for CCM.\nYear: 1995\n\nAbstract: DC and small-signal circuit models of the PWM buck-boost converter for the continuous conduction mode (CCM) are derived. The models take into account parasitic components, such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor on-resistance, and the diode forward resistance and offset voltage. The component values and the parasitics were measured for a prototype converter. The de voltage transfer function and the efficiency of the converter are derived from the de model. Small-signal open-loop transfer functions are derived from the small-signal model. The derivation of the transfer function for an integral-lead controller with the loading effect of the voltage divider network in the feedback loop is given. Small-signal closed-loop transfer functions are derived. Bode plots are given for various transfer functions of the converter.","Title: Sub-Optimum Operation Of Class E Amplifier With Nonlinear Shunt Capacitance At Any Duty Cycle\nYear: 2006\n\nAbstract: An analysis is given for sub-optimum conditions of Class E amplifier with a nonlinear shunt capacitance with a grading coefficient of 0,5 at any duty cycle. By exploiting sub-optimum class E operation, various amplifier parameters such as input voltage, operating frequency, output power, and load resistance can be set as design specifications. An example of a design procedure of the class E amplifier is given. The theoretical results were verified with Pspice simulation using SPICE MOSFET model.","Title: Experimental Static and Dynamic Characteristics of MOS-Controlled Thyristors for Resistive Loads.\nYear: 1995\n\nAbstract: Experimental results are given for a PMOS-controlled thyristor (PMCT). The static I-A-V-AK characteristics of a PMCT were measured using a programmable high power curve tracer for both forward and reverse anode-to-cathode voltage V-AK at different temperatures. The characteristics are similar to the I-D-V-D characteristics of typical p-n junction diodes. The device has a low forward voltage drop at high-current levels, e.g. V-F(AK) = 1.6 V at I-A = 200 A. The dynamic behavior of the PMCT was measured in a single switch configuration under resistive loading. The transient waveforms of anode current i(A), gate current i(G), anode-to-cathode voltage v(AK), and gate-to-anode drive voltage v(GA) were observed at turn-on and turn-off for power levels up to 5 kW. The measured turn-on time was 0.3 mu s and the measured turn-off time was 2.2 mu s. The switching power loss and the conduction power loss were 3 W and 18 W, respectively.","Title: Cmos Zero Cross-Conduction Low-Power Driver And Power Mosfets For Integrated Synchronous Buck Converter\nYear: 2006\n\nAbstract: This paper presents a circuit and a design of a CMOS zero cross-conduction low-power driver for an integrated synchronous buck converter. The circuit has a zero cross-conduction, yielding low-power dissipation and high efficiency. We used the Cadence design tool with 0.18 mu M CMOS technology to implement and verify the functionalities of the low-power buck converter driver. The design criteria of these drivers depend on the power dissipation, delay, and physical size. The DC input voltage of this design is 1.2 V, the DC output voltage is IV, the output current is 120 mA, and the maximum operating frequency is up to 100 MHz. The total size of the driver is around 140 micron(2) Plus the area of an inductor and a capacitor. The designed converter achieved the required specification, and its efficiency is up to 97.9%. This circuit is more efficient than other previous low-power buck converter drivers. The proposed circuit is better than Lee's et al. and ours recent design in terms of efficiency, speed, and layout area. The new circuit is more than 4 times smaller than Lee's circuit. The circuit can be also used in I/O pads for high-current and low-power IC applications.","Title: Derivation of the buck-boost PWM DC-DC converter circuit topology\nYear: 2002\n\nAbstract: The derivation of the buck-boost PWM DC-DC converter circuit is presented. The buck and boost converter circuits are cascaded through an inverting stage. Circuit theory and manipulation will be used to simplify the cascaded circuit into the familiar inverting buck-boost PWM DC-DC converter topology.","Title: Integration Of Class De Inverter For On-Chip Dc-Dc Power Supplies\nYear: 2006\n\nAbstract: A 12.5 mW, 500 MHz class DE power inverter was designed and simulated as an inverter part of dc-dc converters to realize a fully integrated switching power supply using a 1.2 mu m CMOS process. A 20 nH spiral inductor was used in the resonant circuit. The class DE inverter requires lower inductance than PWM buck converter. Soft switching operation enables high conversion efficiency at high operating frequencies. The class DE inverter can be an excellent candidate for on-chip switching converters because of very high efficiency, smaller passive elements, and low peak switch voltage.","Title: Isolated Two-Transistor Zeta Converter With Reduced Transistor Voltage Stress.\nYear: 2011\n\nAbstract: This brief introduces an isolated two-switch Zeta dc-dc converter, along with the steady-state analysis and experimentation. The high transistor voltage stress due to the ringing caused by the resonance of the transformer leakage inductance and the transistor output capacitance is a major drawback in the conventional isolated Zeta converter. With the incorporation of an additional transistor and t...","Title: Active-clamp ZVS two-switch flyback converter\nYear: 2011\n\nAbstract: This paper introduces a zero voltage switching (ZVS) two-switch flyback pulse-width modulated (PWM) DC-DC converter along with the principle of circuit operation and steady-state analysis. The proposed converter topology is the result of incorporating an auxiliary circuit in place of the clamping diodes on the primary side of the conventional hard- switching two-switch flyback converter, resulting in a soft- switching two-switch flyback converter with reduced switch voltage stresses. The auxiliary circuit is an active-clamp circuit made up of two switches and a clamp capacitor. The active clamp circuit recycles the energy stored in the parasitic transformer leakage inductance, facilitates the ZVS operation of all active switches, and limits the voltage stresses of all the active switches to a value less than or equal to the DC input voltage VI. Circuit description, principle of operation, steady-state analysis, and simulation results of the proposed converter are presented.","Title: Feedforward Control With Reference Voltage Modulation\nYear: 1999\n\nAbstract: A feedforward control technique with reference voltage modulation is introduced for PWM buck converter operated in the continuous conduction mode (CCM). The reference voltage is proportional to the de converter input voltage. A steady-state analysis is performed. Experimental results are given. The measured open-loop line voltage regulation was 1.32%/V.","Title: Two-switch flyback PWM DC–DC converter in discontinuous-conduction mode\nYear: 2011\n\nAbstract: The two-switch flyback DC–DC converter is an extended version of the conventional single-switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single-switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two-switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed analysis and design procedure of the diode-clamped two-switch flyback converter operated in discontinuous-conduction mode (DCM). A comparison of power losses of the two-switch and the single-switch flyback converters is given. The two-switch flyback converter was bread-boarded to validate the theoretical analysis. Experimental results from a 20-V/30-W, 100-kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright © 2010 John Wiley & Sons, Ltd.","Title: Margins Of Stability Of Inner-Current Loop Of Peak Current-Mode Controlled Pwm Dc-Dc Converters\nYear: 2009\n\nAbstract: This paper presents expressions for the limiting value of the duty cycle and the minimum value of the slope compensation for marginally stable operation as well as for the normalized crossover frequency, the maximum duty cycle, and the value of the slope compensation at a required phase margin. These quantities describe the performance of the inner-current loop in peak current-mode controlled PWAI dc-dc converters. The derivations are based on the Pade approximation of z = exp(sTs). The results of this paper can be used for the design of the inner-current loop with a specified phase margin.","Title: Derivation of the Cuk PWM DC-DC converter circuit topology\nYear: 2003\n\nAbstract: The derivation of the transformerless Cuk PWM DC-DC converter circuit is presented. Boost and buck PWM DC-DC converter circuits are cascaded through a unity-gain inverting stage. Circuit theory and manipulations I are used to simplify the cascaded circuit into the Cuk PWM DC-DC converter topology.","Title: Two-switch flyback-forward PWM DC-DC converter with reduced switch voltage stress\nYear: 2010\n\nAbstract: This paper introduces a two-switch flyback-forward pulse-width modulated (PWM) DC-DC converter along with the steady-state analysis, simplified design procedure, and experimental verification. The proposed converter topology is the result of integrating the secondary sides of the two-switch flyback and the two-switch forward converters in an anti-parallel connection, while retaining the two-main switches and the clamping diodes on a single winding primary side. The hybrid two-switch flyback-forward converter shares the semiconductor devices on the primary side and the magnetic component on the secondary side resulting in a low volume DC-DC converter with reduced switch voltage stress. Simulation and experimental results are given for a 10-V/30-W, 100 kHz laboratory prototype to verify the theoretical analysis.","Title: Analysis and Design of Class- Power Amplifier\nYear: 2014\n\nAbstract: This paper presents analytical expressions for the class-EM power amplifier, taking into account the fundamental-frequency and harmonic components of output currents in the main and auxiliary circuits. By using the proposed expressions, design values for satisfying not only the class-EM ZVS/ZDVS/ZCS/ZDCS conditions of the main circuit, but also the ZVS condition of the auxiliary circuit can be achieved without applying any tuning process. The analytical predictions agreed with experimental and PSpice-simulation results quantitatively, which showed the validity of analytical expressions given in this paper.","Title: Design Of Class-De Amplifier With Linear And Nonlinear Shunt Capacitances For 25 % Duty Ratio\nYear: 2009\n\nAbstract: The class-E ZVS/ZDS operation within the class-DE amplifier can be easily achieved by adding external shunt capacintaces. This paper presents the analytical expressions for the design of the class-DE amplifier with the shunt capacitances composed of the linear and nonlinear capacitances for the switch-on duty ratio D = 0.25. In the analysis, an equivalent linear shunt capacitance of nonlinear MOSFET output capacitance are defined and derived. The analytical results show good agreement with the experimental ones, which validates our analysis.","Title: Static Characteristics of MOS-Controlled Thyristors - Analysis, Simulation, and Experimental Results.\nYear: 1995\n\nAbstract: An equation for the i(K)-v(AK) static forward characteristic of an MOS-controlled thyristor (MCT) is derived using a four-transistor equivalent model of the device. The Ebers-Moll large-signal model is used for n-p-n and p-n-p bipolar transistors. The equation is similar to that for forward-biased diodes. The equivalent saturation current of the MCT is a function of both the saturation currents and the forward and reverse current gains of the n-p-n and p-n-p transistors. Effects of these parameters on the MCT equivalent saturation current are investigated. Voltages and currents of all transistors that form the MCT equivalent model are simulated using SPICE to explain the behavior of the device in the forward-biased region. Finally, the experimental i(K)-v(AK) characteristics are presented. The calculated and measured i(K)-v(AK) characteristics were in good agreement. The measured ON-voltage drop was 1.6 V at a cathode current of 200 A and a temperature of 300 K. MCTs are especially useful power devices for electric car applications.","Title: Reverse Recovery of Power PN Junction diodes.\nYear: 1995\n\nAbstract: A quasi-steady state approximation is used to derive expressions for the waveforms of minority carrier charge stored in p(+)nn(+) power junction diodes driven by large-signal sinusoidal and ramp voltages. These waveforms are derived by solving a diode charge-control differential equation. Using the charge waveforms, the storage time is determined and the diode current and voltage waveforms are predicted. It is shown that three frequency ranges can be distinguished: (1) low-frequency range in which the reverse recovery is negligible, (2) mid-frequency range in which the reverse recovery is detrimental, but the diode is still of practical value, and (3) high-frequency range where the diode does not exhibit its rectifying properties. A simple method for measuring the minority carrier lifetime is proposed. Experimental results are given for an MR826 East-recovery pn junction diode and a 31DQ06 Schottky diode for operating frequencies of up to 10 MHz. The theoretical and experimental results were in good agreement.","Title: Maximum Drain Efficiency Class F-3 Rf Power Amplifier\nYear: 2011\n\nAbstract: This paper presents a design procedure for the class F-3 RF power amplifier. The required range of the drain current conduction angle for the class F-3 power amplifier is specified. Additionally, an equation for the resistance of the third harmonic resonant circuit is given. Class F-3, AB, and C power amplifiers were designed and simulated to compare their respective performance in terms of efficiency.","Title: Effect of MOSFET gate-to-drain parasitic capacitance on class-E power amplifier\nYear: 2010\n\nAbstract: In this paper, we present analytical expressions for the waveforms and design equations for achieving the ZVS/ZDS conditions in the class-E power amplifier, taking into account the gate-to-drain parasitic capacitance of the MOSFET. We also give a design example along with PSpice simulation and experimental results. The voltage waveforms obtained from both the PSpice simulation and the circuit experiment achieved the class-E ZVS/ZDS conditions completely, which verify the analytical expressions. The results in this paper indicate that it is important to consider the effect of the MOSFET gate-to-drain capacitance for achieving the class E ZVS/ZDS conditions. The experimental power conversion efficiency achieved 92.8 % at output power Po = 4.06 W and operating frequency f = 7 MHz.","Title: Loop gain of the common-gate Colpitts oscillator\nYear: 2011\n\nAbstract: This study presents the derivations of the voltage transfer functions of the amplifier A, the feedback network β, the loop gain T, the closed-loop gain Af and also the characteristic equation for the common-gate (CG) Colpitts oscillator, using the small-signal model of the metal-oxide-semiconductor field-effect transistor (MOSFET) CG Colpitts oscillator. Using the characteristic equation, the expressions for the oscillation frequency of the sinusoidal output voltage and the condition for oscillation in steady state are derived. The characteristic equation is also used to obtain a plot of trajectories of the closed-loop poles of the CG Colpitts oscillator by varying the MOSFET small-signal transconductance gm. The locations of the complex conjugate poles of closed-loop gain that depict the starting and steady-state conditions for oscillations are presented. Nyquist plots of the loop gain are given to illustrate the startup and steady-state conditions of oscillations. Simulation and experimental results to verify the theory are also given.","Title: Design Equations For Off-Nominal Operation Of Class E Amplifier With Nonlinear Shunt Capacitance At D=0.5\nYear: 2013\n\nAbstract: Design equations for satisfying off-nominal operating conditions of the class E amplifier with a nonlinear shunt capacitance for a grading coefficient of 0.5 and the duty cycle D = 0.5 are derived. By exploiting the off-nominal class E operation, various amplifier parameters such as input voltage, operating frequency, output power, and load resistance can be set as design specifications. As a result of the analysis in this paper, the following extension of the usability of the class E amplifier was achieved. With rising up the de supply voltage, the shunt capacitance which achieves the off-nominal operation can be increased. This means that a transistor with higher output capacitance can be used for ZVS operation. This also means that maximum operating frequency which achieves ZVS can be increased. An example of a design procedure of the class E amplifier is given. The theoretical results were verified with an experiment.","Title: Output Characteristics Of Class E Amplifier With Nonlinear Shunt Capacitance Versus Supply Voltage\nYear: 2007\n\nAbstract: Due to the nonlinearity of shunt capacitance of the class E amplifier, the output amplitude of the class E amplifier is not a linear function of the dc supply voltage of the class E amplifier. Estimating this nonlinearity is important to maintain ZVS operation in a situation of variable dc supply voltage, e.g., for a amplitude modulated (AM) power amplifier. However, there are no research results for the output amplitude of class E amplifier with nonlinear shunt capacitance. In this paper, the circuit behavior of the class E amplifier with nonlinear shunt capacitance outside designed nominal conditions is obtained using mathematical processing software MathCAD.","Title: Generalized Design Considerations and Analysis of Class-E Amplifier for Sinusoidal and Square Input Voltage Waveforms\nYear: 2015\n\nAbstract: In this paper, analytical expressions and design equations are presented for a class-E amplifier with MOSFET nonlinear drain-source capacitance and linear gate-drain parasitic capacitance, along with external linear shunt capacitance. The class-E amplifier characteristics are presented as functions of the ratio of the sum of the external linear shunt capacitance and the MOSFET linear gate-drain capacitance to the MOSFET drain-source junction capacitance when the switch voltage is zero. Although the effect of the MOSFET linear gate-drain capacitance is similar to that of the external linear shunt capacitance on the design of the class-E amplifier with a square input voltage, the difference between their effects should be considered for the sinusoidal input voltage, which is one of the most important suggestions in this paper. Additionally, analytical expressions of the output power capability is given, which is considerably affected by the external linear shunt capacitance. Two design examples are presented, taking into account as design specification the output power of 8.7 W and the operating frequency of 4 MHz, along with the PSpice-simulations and experimental waveforms.","Title: Closed-Loop Characteristics of voltage-Mode-Controlled PWM Boost DC-DC converter with an integral-lead Controller.\nYear: 1994\n\nAbstract: A complete analysis of a voltage-mode-controlled pulse-width-modulated (PWM) boost DC-DC power converter is presented using a previously derived small-signal model for continuous conduction mode (CCM). All parasitic components such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor on-resistance, and the diode forward resistance and offset voltage are included in the model. A design procedure for an integral-lead controller including the loading effect of the voltage divider in the feedback loop is given. The Bode plots of the closed-loop control-to-output transfer function, input-to-output transfer function, input impedance, and output impedance are determined and illustrated for three values of the duty cycle. Step response plots of the PWM boost converter in the open-loop and closed-loop cases are shown for changes in line voltage and duty cycle.","Title: Dynamic Performance of MCTS under Inductive Load conditions.\nYear: 1994\n\nAbstract: PMOS-controlled thyristors (PMCTs) were tested in a single-switch configuration under inductive-load hard-switching conditions. The transient current and voltage waveforms during the turn-on and turn-off transitions were observed for 50 A/1000 V devices. The experimental waveforms are given for the anode current, the inductor current, the anode-to-cathode voltage, and the gate-to-anode drive voltage. These waveforms were obtained for periodic gate drive voltage at 6.5 kHz. The test circuit was operated at power levels of up to 370 W. The measured turn-on time was 0.255 mus at an anode-to-cathode voltage of 270 V and the measured turn-off time was 1.6 mus at an anode current of 16 A. The measured storage time was 1 mus. The measured input capacitance of the MCT was 13.5 nF and the output capacitance was 66.7 nF. It was found that the input and output capacitances of PMCTs are approximately linear.","Title: Analysis Of Dynamic And Transient Response Of Frequency Modulated Class E Amplifier\nYear: 2014\n\nAbstract: The dynamic characteristics of the class E power amplifier with frequency modulation are derived. Such an analysis is essential for designing amplitude and frequency modulated amplifier systems such as an EER scheme. Conventionally, an analytical expression for the frequency response of a frequency modulated class E amplifier has not been derived yet. This omission is rectified here by modeling the circuit with both a low-frequency model and a high-frequency model. Further, a time domain waveform is derived from the frequency domain transfer function for some typical time varying drive signals. The analytical results for the frequency response of a 1-MHz class E amplifier are shown to match PSpice simulations and measured values well.","Title: Multiphase resonant inverters with common resonant circuit\nYear: 2014\n\nAbstract: A new family of Class D resonant inverters is proposed in this paper. Multiple identical series resonant inverters are paralleled using intercell transformers to form phase-controlled multiphase resonant inverter with a common resonant circuit. Inverters can operate at constant frequency utilizing phase-shift control to regulate output. A frequency-domain analysis of the proposed family is performed. An experimental prototype of a three-phase resonant inverter with common resonant circuit was built and extensively tested at an output power of 550 W and switching frequency of 167 kHz.","Title: Analytical design procedure for resonant inductively coupled wireless power transfer system with class-E2 DC-DC converter\nYear: 2014\n\nAbstract: This paper presents a resonant inductive coupling wireless power transfer (RIC-WPT) system with a class-E2 dc-dc converter along with its analytical design procedure. By using the class-E inverter as a transmitter and the class-E rectifier as a receiver, the designed WPT system can achieve a high power-conversion efficiency because of the class-E ZVS/ZDS conditions satisfied in both the inverter and the rectifier. In the simulation results, the system achieved 65.9 % overall efficiency at 5 W (50 Ω) output power, coil distance 30 cm, and 5 MHz operating frequency. Additionally, the simulation results showed good agreement with the design specifications, which indicates the validity of the design procedure.","Title: Modeling and Analysis of Class-E Amplifier With a Shunt Inductor at Sub-Nominal Operation for Any Duty Ratio\nYear: 2014\n\nAbstract: This paper presents analytical expressions for the sub-nominal operation, which is only the zero current switching (ZCS) condition, of the class-E power amplifier with a shunt inductor at any duty ratio. The duty ratio is considered not only as a design specification but also as an adjustment parameter. In the sub-nominal operation with any duty ratio, both the peak switch voltage and the peak switch current can be set as design specifications due to two more degrees of design freedom in comparison with the class-E nominal amplifier at the fixed duty ratio. Additionally, it is also seen that the duty ratio affects the maximum operating frequency and the output power capability with ZCS condition. A design example of the class-E ZCS amplifier with a shunt inductor under the specifications of peak switch voltage and peak switch current is given. The measurement and a simulation by circuit simulator results agreed with the analytical expressions quantitatively, which show the validity of our analytical expressions.","Title: Voltage-clamped class E amplifier with a Zener diode across the switch\nYear: 2002\n\nAbstract: The class E amplifier with a clamped switch peak voltage using a Zener diode is proposed and analyzed A higher output power is obtained when the maximum switch voltage is clamped. Design equations are derived for the output power and power losses. The effect of the Zener diode on the switch voltage waveform, output power, and efficiency are examined. The experimental verification is presented using a prototype circuit.","Title: A method for predicting the ZVS condition for the class E amplifier\nYear: 2002\n\nAbstract: A method for predicting the ZVS condition before turning the switch on is presented for the class E amplifier operating with D=0.5. The prediction is obtained in real- time by observing the switch current waveform and the shunt capacitor current waveform with a simple analog- digital circuit. Using this method, a control circuit that ensures ZVS condition becomes feasible.","Title: Class-E MOSFET low-voltage power oscillator\nYear: 2002\n\nAbstract: A class-E oscillator based on the Motorola MTP3055E power MOSFET was analyzed, designed, built, and tested. The supply voltage was 4.5 V, while the output power was 1 W. The oscillator feedback network per- mits the use of MOSFETs with a high gate-source volt- age. The efficiency and output power versus frequency, and the frequency versus the voltage supply were measured.","Title: Voltage-clamped class E amplifier with a Zener diode across the choke coil\nYear: 2002\n\nAbstract: A class E amplifier with a clamped switch peak voltage with a Zener diode across the choke inductor is proposed and analyzed. Power loss in the Zener diode is reduced to 2/3 of that in the amplifier with a Zener diode across the switch. The effect of the Zener diode on the switch voltage waveform, output power, and efficiency are examined and experimentally verified.","Title: Impact of boost converter parameters on open-loop dynamic performance for DCM\nYear: 2002\n\nAbstract: The impact of a PWM DC-DC boost converter parameters on its open-loop dynamic performance is studied. The parameters considered are: the load resistance R, the filter capacitor ESR rC, and the inductor ESR r. The principle of energy conservation approach is used to take into account parasitic resistances of the transistor and diode in the inductor ESR. The parameter impact has been evaluated by using a small-signal circuit model composed of current-controlled current sources. Bode plots of the control-to-output transfer function are given using R, rC, and r as parameters. Plots of poles and zeros are given as functions of these three resistances. These plots clearly show how the dynamic performance of the boost converter is affected by these parameters.","Title: High-efficiency microwave BJT power amplifier simulation\nYear: 2002\n\nAbstract: Simulation results of a Siemens BFP490 BJT power amplifier for a frequency range 8-11 GHz are presented. It was shown that the output network input impedance is inductive and the collector current is negative during a part of the AC cycle, when the amplifier operates in high-efficiency mode.","Title: Feasibility study of on-chip class E DC-DC converter\nYear: 2003\n\nAbstract: A 200 mW, 800 MHz class E DC-DC converter is designed using a 0.6 μm CMOS process and then simulated. A 22 nH spiral inductor is used in the resonant circuit. An integrated feedback controller with a VCO is used for the output voltage regulation. It is shown that the class E inverter is an excellent candidate for on-chip switching converters because of very high efficiency, and the inductor can be minimized at high operating frequencies. The simulated converter efficiency was 72% at 4.5 V output voltage, 200 mW output power, and 800 MHz switching frequency.","Title: Voltage-clamped class E amplifier with transmission-line transformer\nYear: 2005\n\nAbstract: A high switch peak voltage is a disadvantage of the class E amplifier in some applications. A lossless voltage clamp method with a transformer and a diode has been proposed as a remedy for the high peak switch voltage. However, this circuit suffers from a large ringing due to the transformer leakage inductance, which is superimposed on the clamped voltage and partially eliminates the effect of the voltage clamping. In this paper, a switch voltage clamping using a transmission-line transformer is proposed to reduce the ringing. The proposed concept was verified with an experimental voltage-clamped class E amplifier at 4 MHz and 2.9 W.","Title: DC and AC analysis of buck PWM DC-DC converter with peak-voltage-modulation feedforward control\nYear: 1999\n\nAbstract: DC and small-signal analyses are given for the open-loop buck pulse-width modulation (PWM) DC-DC converter with peak-voltage-modulation (PVM) feedforward control. A DC model is used to derive DC input-to-output transfer function taking into account parasitic components, such as the MOSFET on-resistance, diode forward resistance, and diode offset voltage. A small-signal model is used to derive the audiosusceptibility. It is shown that ideally the audiosusceptibility is zero for the buck converter with PVM feedforward control","Title: Power losses and efficiency of class E RF power amplifiers at any duty cycle\nYear: 2001\n\nAbstract: Class E RF power amplifiers offer very high efficiency with relatively few components. Component values used in class E circuit design are directly dependent upon the selection of duty cycle. This paper presents an analysis of the effect of duty cycle on power loss in each of the components and total efficiency, and includes experimental results","Title: Buck PWM DC-DC converter with reference-voltage-modulation feedforward control\nYear: 2001\n\nAbstract: DC and small-signal analyses are given for the open-loop buck pulse-width modulated (PWM) DC-DC converter with reference-voltage-modulation (RVM) feedforward control. A DC model is used to derive DC input-to-output transfer function taking into account parasitic components, such as the MOSFET on-resistance, diode forward resistance, and diode offset voltage. A small-signal model is used to derive the audiosusceptibility and input impedance","Title: Eddy-current power loss in laminated iron cores\nYear: 2001\n\nAbstract: This paper presents an analysis of power losses in gapless laminated iron cores at high frequencies. First, the magnetic field intensity is found. Next, the eddy current density is determined. Finally, expressions for the power loss density and the power loss per unit volume of an iron core are derived","Title: Low-voltage self-oscillating class E electronic ballast for fluorescent lamps\nYear: 2006\n\nAbstract: In this paper, electronic ballast based on the class E oscillator with a capacitive impedance inverter is presented. The ballast allows us to supply an instant-start fluorescent lamp from a 12 V dc power source. The class E oscillator allows for increasing the efficiency using a simple structure with only one switch without a driving circuit. Due to the anti-parallel diode integrated into the switch, the ZVS condition is satisfied in the ignition mode, maintaining high efficiency. One of the applications of the ballast is mobile equipment, where compact independent power sources are used, for example, batteries or solar cells. The ballast was designed with the following parameters: VDD = 12 V, Po = 18 W, fo = 440 kHz. The measured efficiency was 83%, the output power was 18.5 W, and the dc supply power was 22.3 W at the operating frequency of 444.44 kHz","Title: Off-Nominal Operation of Class-E Amplifier at Any Duty Ratio\nYear: 2007\n\nAbstract: Design equations for satisfying the suboptimum operating condition, i.e., only the zero-voltage switching (ZVS) condition, of a class-E amplifier with a linear shunt capacitance at any duty ratio are derived. By exploiting the suboptimum class-E operation, various amplifier parameters such as operating frequency, output power, load resistance, and component values can vary, while the ZVS operation and high efficiency can be achieved. An example of a design procedure of the class-E amplifier is given. The theoretical results were verified with PSpice simulation and an experiment.","Title: ZVS operating frequency versus duty ratio of class E amplifier with nonlinear shunt capacitance\nYear: 2008\n\nAbstract: The maximum operating frequency of the class E amplifier with nonlinear shunt capacitance depends on the transistor duty ratio. It varies with the duty ratio under zero- voltage switching (ZVS) and zero-derivative switching (ZDS) conditions at fixed values of the output power, dc supply voltage. Therefore, the design of the class E amplifier with given values of the shunt capacitance, the output power, dc supply voltage is possible by adjusting the operating frequency. The operating frequency has the maximum value when the duty ratio DON is approximately 0.36 at VDD/Vbi = 1 . It is also shown that the maximum operating frequency is higher when the dc supply voltage VDD is lower.","Title: Maximum Operating Frequency of Class-E Amplifier at Any Duty Ratio\nYear: 2008\n\nAbstract: This paper shows that the maximum operating frequency of the class-E power amplifier depends on the transistor duty ratio. The maximum operating frequency increases as the duty ratio decreases under zero-voltage switching and zero-derivative switching conditions at fixed values of the output power, dc supply voltage, and shunt capacitance.","Title: Analysis of dynamic frequency response of class E amplifier\nYear: 2009\n\nAbstract: A dynamic response of the output voltage to the input supply voltage VDD of a class E amplifier is derived with modeling the circuit by a low-frequency model and a high-frequency model. If the perturbation frequency is much lower than the switching frequency, the state-space averaging model of the class E amplifier can be approximated as a single-pole low-pass filter composed of the choke inductance LRFC and the parallel combination of the switch resistance and the shunt capacitor resistance. The analysis in this paper is based on the steady-state behavior outside the designed conditions given in. Hence, the derivation is applicable even if the class E amplifier is operated in off-tuned conditions. The analytical results for the frequency response of a 1 MHz class E amplifier matched well with Pspice simulations at the perturbation frequency less than 100 kHz.","Title: Power efficiency calculation of class E amplifier with nonlinear shunt capacitance\nYear: 2010\n\nAbstract: Power efficiency of a class E RF power amplifier versus dc supply voltage VDD when the shunt capacitance of the class E amplifier is a nonlinear capacitance with the grading coefficient m = 0.5 is obtained. In the calculation of power efficiency, switching loss due to non-zero turning on of the MOSFET, power loss due to forward voltage drop of the MOSFET body diode, and power loss due to MOSFET on-resistance are incorporated. It is found that the highest power efficiency is obtained at a lower dc supply voltage than the designed dc supply voltage, even though the circuit was designed to achieve the nominal operation at the designed dc supply voltage. The calculation was performed with Mathcad programming and the results were verified with Pspice simulations.","Title: Control-to-output and duty ratio-to-inductor current transfer functions of peak current-mode controlled dc-dc PWM buck converter in CCM\nYear: 2010\n\nAbstract: The control-to-output and the duty ratio-to-inductor current transfer functions of peak current-mode controlled PWM dc-dc buck converter in CCM are derived and illustrated. The closed inner-current loop and the power stage inductor current-to-output voltage transfer functions are used to derive the control-to-output transfer function of the peak current-mode controlled buck converter in CCM, which is essential for the outer-voltage loop controller design. A small-signal model including parasitic components and delay is used to derive the power stage transfer function, necessary for proper analysis of the power stage. The loop gain of the inner-current loop is derived and is shown that it is independent of converter topology.","Title: Comparison of Wide- and High-Frequency Duty-Ratio-to-Inductor-Current Transfer Functions of DC–DC PWM Buck Converter in CCM\nYear: 2012\n\nAbstract: Wide- (WF) and high-frequency (HF) small-signal models are presented for pulsewidth-modulated dc-dc buck converter power stage. An exact duty-ratio-to-inductor-current transfer function is derived using the WF model and compared to an approximate transfer function derived using the HF model for the buck converter power stage in continuous conduction mode. The theoretical results are validated using experimental results.","Title: Small-signal modeling of PWM Z-source converter by circuit-averaging technique\nYear: 2011\n\nAbstract: This paper presents the small-signal modeling of pulse-width modulated (PWM) Z-source converter (ZSC) operating in continuous conduction mode (CCM) by circuit averaging technique. The averaged large-signal, dc, and time-invariant linear small-signal circuit models of PWM ZSC power stage operating in CCM are derived. The small-signal modeling focuses on the dynamics introduced by the Z network present in the ZSC. Based on the small-signal model derived, the small-signal model required to derive the open-loop input-to-capacitor voltage transfer function is derived. The open-loop input-to-capacitor voltage transfer function is derived, and the associated theoretical Bode plots are illustrated using Matlab and is verified by circuit simulation. The theoretical results were in excellent agreement with the simulation results, validating the ac small-signal model and the derived input-to-capacitor voltage transfer function.","Title: Power conversion efficiency of class-E power amplifier outside nominal operation\nYear: 2011\n\nAbstract: This paper gives analytical expressions for the output power and the power conversion efficiency of the class-E power amplifier outside the class-E ZVS/ZDS switching conditions. The analytical predictions agreed with the experimental results quantitatively, which indicates the validity of the analytical expressions. Moreover, a design example applying the analytical expressions for the power conversion efficiency is given. By using the analytical expressions, it is possible to design the class-E amplifier, which improves the power conversion efficiency compared with that of the class-E amplifier satisfying the class-E ZVS/ZDS conditions.","Title: Analysis of Class-DE Amplifier With Linear and Nonlinear Shunt Capacitances at 25% Duty Ratio\nYear: 2010\n\nAbstract: The class-E zero-voltage switching/zero-derivative switching operation within class-DE amplifiers can be easily achieved by adding external shunt capacitances. This paper gives the analytical expressions for the designs of the class-DE amplifiers with the shunt capacitances composed of linear and nonlinear capacitances for any grading coefficient m of MOSFET body junction diodes at the switch-on duty ratio D = 0.25. In the analysis, an equivalent linear shunt capacitance of the nonlinear MOSFET drain-source parasitic capacitances is derived. Analytical results show good agreements with the simulation and experimental ones, which validate our analysis.","Title: Power Losses and Efficiency of Class-E Power Amplifier at Any Duty Ratio\nYear: 2004\n\nAbstract: This paper presents an analysis of the effect of duty ratio on power loss and efficiency of the Class-E amplifier. Conduction loss for each Class-E circuit component is derived and total amplifier losses and efficiency are expressed as functions of duty ratio. Two identical 300-W Class-E amplifiers operating at 7.29 MHz are designed, constructed, and tested in the laboratory. Dependence of total e...","Title: Frequency-Dependent Resistance Of Litz-Wire Square Solenoid Coils And Quality Factor Optimization For Wireless Power Transfer\nYear: 2016\n\nAbstract: In order to achieve the highest efficiency of wireless power transfer (WPT) systems, the quality factor of the resonant coil should be as high as possible. Due to the skin effect and the proximity effect, the coil resistance increases with the increase in the frequency. The highest quality factor exists for the optimal frequency together with the corresponding frequency-dependent inductor resistance. This paper employs the Biot-Savart law to calculate the magnetic field strength, which results in the proximity-effect resistance in single-layer litz-wire square solenoid coils without a magnetic core. A strand-number coefficient is introduced to reflect the influence of the strand number inside the wire bundle on the proximity-effect resistance. The coefficient is obtained through simple inductor resistance measurements for various numbers of litz-wire strands. The optimal frequency for the highest quality factor is derived based on the resistance evaluation. Several prototype coils were manufactured to verify the resistance analysis. Two 50 cm x 50 cm square coils were employed to construct a WPT prototype. The maximum dc-dc efficiency of this WPT was about 75% at 100-cm distance.","Title: Small-signal modeling of the PWM boost DC-DC converter at boundary-conduction mode by circuit averaging technique\nYear: 2015\n\nAbstract: This paper presents the derivation of the small-signal model of the boost converter operating in the boundary-conduction mode (BCM) using the circuit averaging technique. The essential transfer functions such as the input-to-output voltage transfer function M\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">v</inf>\n and the control-to-output transfer function T\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">p</inf>\n are derived using the linear small-signal model. Further, the characteristics of these transfer functions are analyzed using a representative design example. The switching circuit and the small-signal model are tested on a simulator to validate the proposed model.","Title: Transfer functions of a transformer at different values of coupling coefficient.\nYear: 2016\n\nAbstract: The low- and mid-frequency model of the transformer with resistive load is analysed for different values of coupling coefficients. The model comprising of coupling-dependent inductances is used to derive the following characteristics: voltage gain, current gain, bandwidth, input impedance, and transformer efficiency. It is shown that in the low- and mid-frequency range, the turns ratio between the...","Title: Analysis and design of class E power amplifier considering MOSFET parasitic input and output capacitances.\nYear: 2016\n\nAbstract: In this study, design theory and analysis for the class E power amplifier (PA), considering the metal oxide semiconductor field effect transistor (MOSFET) parasitic input and output capacitances, are proposed. The input resistance and capacitances cause non-ideal input voltage at gate terminal, which affect the specifications of the class E PA. In the proposed study, non-linear drain-to-source, li...","Title: Sensitivity of effective relative permeability for gapped magnetic cores with fringing effect.\nYear: 2017\n\nAbstract: Magnetic component tolerances are caused by variations in air-gap and core relative permeability. This study presents the derivation for sensitivity of effective relative permeability to variations in the relative core permeability and relative gap length for magnetic cores with and without fringing effect. The expressions for the fringing factor and effective relative permeability for the magneti...","Title: High switching frequency performance of E-GaN FETs and silicon MOSFETs.\nYear: 2017\n\nAbstract: This paper aims at achieving the following objectives: (a) evaluate and compare the power loss during switching transitions in the gallium nitride (GaN) FETs and silicon (Si) MOSFETs, (b) determine the frequency capability of the GaN and Si transistors, when used in hard-switching power electronic circuits, and (c) evaluate the power-performance of the synchronous buck (SB) dc-dc power converters employing GaN and Si transistors operating at different switching frequencies. The GaN transistors in EPC9037 switching network module are considered as the benchmark devices and their properties are compared with the silicon n-channel transistors with identical voltage and current ratings. Simulation results are provided for the SB converter illustrating the switching frequency limitation of the Si MOSFETs and the extended frequency capability of GaN FETS. Experimental results are provided to validate the analytical predictions.","Title: Analysis and Design of Choke Inductors for Switched-Mode Power Inverters.\nYear: 2018\n\nAbstract: This paper presents the design, analytical estimation of power losses, and experimental measurement of choke inductors for switched-mode power inverters. The described approach is applicable to a wide variety of circuits such as Class-E inverters and converters. The expressions required to design the magnetic core in the choke inductor using the area-product (Ap) method are given. The equations fo...","Title: Dc Analysis And Design Of A Pwm Buck Converter Operated As A Dynamic Power Supply\nYear: 2017\n\nAbstract: Modern energy transmission and signal reproduction techniques rely upon power amplifiers that must operate with high efficiency. An increasingly popular technique for addressing this problem involves replacing the fixed power amplifier supply voltage V-DD with a controlled, variable voltage provided by a dynamic power supply. Although pulse-width modulated dc-dc buck converters typically function as fixed-output supplies, this paper provides new theoretical dc analysis for operation wherein the output voltage is controlled and continuously variable over a wide range. A design procedure for the variable-output buck converter is derived. Key device parameters affecting converter speed and efficiency are identified. The dc analysis and design procedure are verified experimentally, with calculated and measured parameters shown to be in good agreement. Copyright (c) 2016 John Wiley & Sons, Ltd.","Title: Analytical Optimization Of Solid-Round-Wire Windings\nYear: 2013\n\nAbstract: In this paper, an analytical optimization of solid-round-wire windings conducting sinusoidal current is performed. New closed-form analytical equations are derived for the normalized solid-round-wire diameter to achieve minimum ac winding losses for sinusoidal current. Approximations of Dowell's equation are used to derive expressions for normalized diameter at the local minimum of winding ac resistance and normalized critical diameter. An equation for the winding ac resistance at the local minimum is derived. Additionally, equations for the normalized diameter at the local maximum of ac resistance and the normalized boundary diameter between low-and medium-frequency ranges are given. The formulas enable inductor and transformer designers to minimize winding loss without utilizing finite-element method analysis. Experimental verification of the presented theory is given.","Title: Subnominal Operation of Class-E Nonlinear Shunt Capacitance Power Amplifier at Any Duty Ratio and Grading Coefficient.\nYear: 2018\n\nAbstract: This paper presents an analytical model to design a class-E power amplifier under only zero-voltage-switching (ZVS) term with the MOSFET nonlinear drain-source shunt parasitic capacitance that is named as the subnominal operation. The presented analysis is performed under any grading coefficient m of MOSFET body junction diode and any duty ratio D. The grading coefficient m along with the switchin...","Title: Zero-Voltage Switching Operation of Transformer Class-E Inverter at Any Coupling Coefficient.\nYear: 2019\n\nAbstract: This paper presents a complete design methodology of a Class-E inverter with a loosely coupled transformer under zero-voltage switching conditions. At a selected maximum coupling coefficient, the inverter satisfies both zero-voltage switching (ZVS) and zero-derivative switching (ZDS) conditions to achieve a high efficiency. As the coupling coefficient is decreased from its maximum value to zero, t...","Title: MLMVNNN for Parameter Fault Detection in PWM DC-DC Converters and Its Applications for Buck and Boost DC-DC Converters.\nYear: 2019\n\nAbstract: This paper presents an effective approach to the fault diagnosis of pulsewidth modulated (PWM) DC-DC power converters. It is based on a multilayer multivalued neuron neural network with a complex QR decomposition. This network is used to identify the parameter values running out of tolerance range in two topologies of PWM DC-DC converters, namely, the buck and boost circuits. The proposed techniqu...","Title: Nonlinear Modelling And Control Of Pwm Dc-Dc Buck-Boost Converter For Ccm\nYear: 2018\n\nAbstract: In this paper, a nonlinear model of inverting pulse-width-modulated buck-boost converter for continuous conduction mode is introduced based on the large-signal averaging technique. The simulation of the nonlinear buck-boost model is performed in MATLAB/SIMULINK and compared with the corresponding circuit in SaberRD simulator for validation purpose. Additionally, a nonlinear control scheme of cascaded proportional-integral sliding-mode current controller is designed. The equivalent control law, existence, and stability conditions are introduced. The simulation results show that the proposed control system enhances the regulation performance, removes the steady-state error, and provides robust tracking against large disturbances.","Title: High-Frequency Single-Switch Zvs Inverter For Driving Capacitive Loads\nYear: 2018\n\nAbstract: This paper introduces a new switched-mode ZVS inverter that is suited to operate at high frequencies with rapid transitions. This topology includes small passive storage elements, low-voltage stress, and fast dynamic response. The single-switch inverter, which has a ground-ended transistor, can be implemented to achieve zero-voltage switching at switching frequencies of several MHz. A tuned resonant network is utilized to alleviate switch voltage stress. The resonant network, which has the desired drain-source impedance, shapes the switch voltage into a quasi-rectangular waveform. The principle of operation, design procedure, and power loss analysis of the proposed circuit are given. The new circuit prototype is designed, simulated, and built at 20 MHz. The performance of the topology is also demonstrated via experimental results. The proposed circuit can be used as a gate-drive circuit for high frequency applications.","Title: Averaged Small-Signal Model of PWM DC-DC Converters in CCM Including Switching Power Loss.\nYear: 2019\n\nAbstract: This brief proposes an improved averaged small-signal model of pulse-width modulated dc-dc power converters operated in continuous-conduction mode, which includes a resistance that corresponds to the switching power loss. Through this model, the switching power loss can be incorporated into existing averaged small-signal dynamic models. The proposed approach is based on the principle of conservation of energy. The expressions for the equivalent switching-loss resistance for the basic converter topologies are derived. The improved dc and small-signal models of the switching network are given. A boost dc-dc converter is considered as an example. The effect of the switching-loss resistance on the small-signal control-to-output transfer function is shown. Experimental results are given and the theoretical predictions have been validated.","Title: Fault detection of resonant inverters for wireless power transmission using MLMVNN\nYear: 2016\n\nAbstract: An effective approach, based on neural networks, to the fault diagnosis of dc-ac resonant inverters is presented. A MultiLayer MultiValued Neuron neural Network (MLMVNN) with a complex QR-decomposition is used to identify parameter value changing (i.e. fault detection) on a Class-E resonant inverter through steady state measurements of voltages and currents.","Title: Fault detection in Class-E 2 resonant converters\nYear: 2017\n\nAbstract: DC-DC converter reliability is of primary interest due to their key role in electronic systems. This paper proposes a diagnostic algorithm, which can be easily implemented in digital programmable device for MOSFET fault detection and identification. An improvement over the existing technique is presented, and its rapid fault detection capability is demonstrated. The two basic faults, namely the short circuit (SCF) and the open circuit fault (OCF) are identified by analyzing the current through the choke inductance. Upon identification of the fault signature, techniques to mitigate the after-effects are discussed. To validate the algorithm, a simulation on a Class-E 2 resonant converter is presented.","Title: Design of zero-voltage-ripple buck dc-dc converter\nYear: 2017\n\nAbstract: This paper presents the design of a zero-voltage-ripple (ZVR) buck dc-dc converter. The circuit uses an auto-transformer for ripple cancellation in the output voltage. The principle of operation is discussed in brief. The relationship between the currents through the magnetizing inductance and the auto-transformer windings is developed. The auxiliary inductance for ripple cancellation in series with the secondary winding is determined. The expression for the auxiliary inductance is derived. A laboratory prototype of a buck converter with supply voltage 12 V, output voltage voltage 5 V, switching frequency 500 kHz, and output power 10 W was built. Simulation and experimental results are provided validating the theoretical predictions.","Title: Semiconductor losses of PWM buck DC-AC converter operated as dynamic power supply\nYear: 2017\n\nAbstract: This paper presents a method for calculating the semiconductor losses in asynchronous and synchronous PWM buck converters when operated as a fixed-VI, fixed-RL, variable-Vo dynamic power supply. Equations are derived for MOSFET switching and conduction losses in both circuits, as well as diode conduction and forward-voltage losses. This work also compares the two topologies from the perspective of semiconductor losses to determine which circuit is inherently more efficient. The low-side MOSFET of the synchronous converter is shown via analysis and simulation to contribute the most significant power loss, thus demonstrating the asynchronous dc-ac converter topology is generally more efficient if designs are otherwise comparable.","Title: Audio-susceptibility of inner loop of true-average current-mode controlled buck dc-dc converter\nYear: 2017\n\nAbstract: The audio-susceptibility of the average current-mode controlled buck dc-dc converter in continuous-conduction mode is presented in this paper. The average current-mode control scheme used in this paper regulates the true average component of the sensed inductor current and is not affected by a high inductor current ripple at low duty ratios. The principle of negative feedback for converters with the average current-mode control is discussed in brief. The input voltage-to- inductor current disturbance transfer function is derived using the averaged, linear small-signal model. The loop gain transfer function has been analyzed to satisfy the closed-loop requirements. The closed-inner-loop input voltage-to-inductor current transfer function and the closed-inner-loop input-to-output voltage transfer functions are determined. An example buck converter is used and the characteristics are analyzed in detail. Simulation results are presented for the designed buck converter validating the theoretical predictions.","Title: Reliability analysis and electrical characterization of a Class-E resonant inverter\nYear: 2018\n\nAbstract: One of the most interesting challenges in power electronics is increasing the circuit reliability. This can be achieved by reducing the power losses and, therefore, increasing the power conversion efficiency. Conduction and switching losses in power MOSFETs are the major contributions to the converter overall power loss, which becomes a serious problem in high-power conversion applications. Resonant converters, which represent an interesting solution to reduce switching losses, are based on a resonant tank composed of inductors and capacitors tuned to resonate at a specific frequency. The resonance forms the voltage and/or current waveforms so that, under optimal conditions, the MOSFET turns on at zero-voltage switching (ZVS) and zero-derivative switching (ZCS). This drastically reduces the switching losses. Also, new semiconductor materials such as SiC or GaN are capable to operate at an increased switching frequency and reduced both conduction and switching losses. In this paper, the reliability of a Class-E resonant inverter is analyzed to identify the most critical elements of the circuit. The reliability prediction has been carried out based on MIL-HDBK-217 handbook. The Mean Time Between Failures (MTBF) and the failure rate λp are derived. Voltage and current values of all components utilized in this analysis are based on data achieved by experimental results.","Title: Design and Characterization of Single-Layer Solenoid Air-Core Inductors\nYear: 2019\n\nAbstract: This study presents the design and experimental characterisation of single-layer solenoid air-core inductors. The analytical expressions for the winding inductance, self-capacitance, and winding resistance are derived. The inductor properties are analysed up to the first self-resonant frequency. The procedure to design air-core inductors for high-frequency (HF) applications is provided. Experiment...","Title: Analysis of Class-DE PA Using MOSFET Devices With Non-Equally Grading Coefficient\nYear: 2019\n\nAbstract: The design and analysis of a new operation-mode of the class-DE power amplifier (PA) using two MOSFETs with the non-equal grading coefficient is introduced. The PA uses the optimum shunt capacitance for each MOSFET to achieve zero voltage switching (ZVS) condition and wide range for the load-resistance point of view. As compared with the conventional class-DE PA, this configuration has low value o...","Title: A Novel Design Methodology For Extended Continuous Class-F Power Amplifiers In Wireless Applications\nYear: 2021\n\nAbstract: In this paper, an extended continuous class-F power amplifier (PA) is investigated, designed, and fabricated. The new auxiliary parameter (beta + alpha cos(2)theta) , is proposed to increase the efficiency in comparison with the old auxiliary parameter (1 + delta cos theta). A novel methodology based on the smith chart design space and the proposed auxiliary parameter is introduced and analyzed. The design methodology, by controlling harmonic interferences, expands the amplifier bandwidth to below 1 GHz (up to 200 MHz). The laterally diffused metal-oxide-semiconductor (LDMOS) is selected, and an optimal bias point for its best performance is considered. Also, microstrip feedback based on the low-impedance coupled line is designed to accomplish transistor unconditional stability. Then, a ladder network based on the radial lines is designed as a harmonic control circuit, which controls harmonics up to 5th into the proposed design space. To verify this design approach, an extended continuous class-F power amplifier is designed and fabricated to operate at 0.2-1.7 GHz frequency range. Measurement results of the implemented PA shown that the output power of 38-40.2 dBm and the power gain of 13-15.2 dB were obtained. In addition, the final PA achieved a remarkable 53-79% drain efficiency over the whole operation bandwidth."],"string":"[\n \"Title: Modelling Winding Losses in High-Frequency Power inductors.\\nYear: 1995\\n\\nAbstract: A high-frequency model of iron-powder-core inductors is studied. The skin and proximity effects that cause the winding parasitic resistance to increase with the operating frequency are considered. The inductor self-resonance due to the parasitic capacitances is taken into account as well. The frequency response of the inductor model is compared to that of an experimentally tested iron-powder-core inductor. Expressions giving the ac resistance as a function of the operating frequency are given. These expressions allow for an accurate prediction of the inductor power loss over a wide frequency range. The measured and calculated values of the inductor impedance magnitude and phase, the real and imaginary parts of the inductor impedance, the inductance, and the inductor quality factor are plotted versus frequency and compared. Theoretical results were in good agreement with those experimentally measured. A design procedure for solid wire winding inductors based on the results of the inductor modelling is also given in the paper.\",\n \"Title: Sample And Hold Effect In Pwm Dc-Dc Converters With Peak Current-Mode Control\\nYear: 2004\\n\\nAbstract: The sample and hold effect, or quasi-digital (discrete) behavior, of constant-frequency peak current-mode control (PCM) in pulse-width modulated DC-DC converters is presented in a manner consistent with the physical behavior of the circuit. This approach developes a transfer function using control theory that captures the quasi-digital behavior encountered when the current control loop is closed in PCM. The new transfer function accurately captures the current loop behavior, leading the way for a complete linear time-invariant system circuit for PWM DC-DC converters. This work improves upon previous derivations by remaining true to the physical behavior of the circuit while resulting in a rational transfer function that can be used in a mutliple loop complete linear system circuit to accurately predict converter behavior due to changes in input voltage, output current, and reference voltage.\",\n \"Title: Bandwidth of Current Transformers\\nYear: 2009\\n\\nAbstract: Bandwidth is one of the important performance parameters of current transformers. Transformers are required to have adequate bandwidth to regenerate the measured current, apart from uncertainties that are caused by the nonsinusoidal waveforms along with harmonics. An expression for the transresistance of the current transformer in terms of parasitic components is derived. Approximate expressions f...\",\n \"Title: Voltage-Loop Power-Stage Transfer Functions With MOSFET Delay for Boost PWM Converter Operating in CCM\\nYear: 2007\\n\\nAbstract: Open-loop transfer functions can be used to create closed-loop models of pulsewidth-modulated (PWM) converters. The closed-loop small-signal model can be used to design a controller for the switching converter with well-known linear control theory. The dynamics of the power stage for boost PWM dc-dc converter operating in continuous-conduction mode (CCM) are studied. The transfer functions from ou...\",\n \"Title: Measurement of open-loop small-signal control-to-output transfer function of a PWM boost converter operated in DCM\\nYear: 2002\\n\\nAbstract: A practical procedure for measuring the control-to-output transfer function of a PWM boost converter operated in discontinuous conduction mode (DCM) is given. It is shown that a simple, low cost measurement setup can be used to test a boost converter and verify a small-signal model of PWM boost converter.The results of this work shows that a frequency-domain description of a PWM dc-dc boost converter can be achieved by using a simple measurement setup. Moreover, the frequency behavior of the model considered here yields accurate results for small-signal, frequency-domain representation of the converter.Therefore, the model can be used to derive the expressions and Bode plots of the control-to-output transfer function. Finally, the proposed method can be utilized in designing an appropriate feedback loop of the converter.\",\n \"Title: Small-signal duty cycle to inductor current transfer function for boost PWM DC-DC converter in continuous conduction mode\\nYear: 2004\\n\\nAbstract: The small-signal transfer function from duty cycle to inductor current is derived for the boost DC-DC converter operating in continuous conduction mode (CCM). The transfer function is found for two cases, the converter with a resistive load, and with a current sink load. The derivations are performed using an averaged circuit small-signal model of the boost converter for CCM. The transfer function can be used to model the current loop of boost PWM converters with peak current-mode control (PCM).\",\n \"Title: Analysis and design of class DE amplifier with nonlinear shunt capacitances\\nYear: 2009\\n\\nAbstract: In this paper, equations for waveforms and design relationships are derived for class DE amplifiers with nonlinear shunt capacitances. Using the analytical waveform equations, it is shown that the nonlinearity of the shunt capacitances affects the waveforms only during the dead-time intervals. Additionally, the waveforms with nonlinear and linear shunt capacitances are not very different if class E zero-voltage switching/zero-derivative switching conditions are satisfied. The operation of a class DE amplifier has two dead-time intervals in one period. The switch-voltage waveforms for both dead-time intervals exhibit symmetry. Therefore, the nonlinearity does not have any effect on the series-resonant-circuit elements. As a result, analytical design equations indicate that the series-resonant-circuit elements are independent of the nonlinearity of the shunt capacitances when the supply voltage and the output power are given as design specifications, which is an important result of this paper. The validity of our analysis is confirmed by PSpice simulations and the circuit experiment.\",\n \"Title: Class-N high-frequency power amplifier\\nYear: 2002\\n\\nAbstract: A new class of high-efficiency amplification is introduced. It based on reducing of time-average dissipated in transistor power instead of state-of-the-art reducing of instantaneous dissipated power. It becomes possible due the influence of capacitances currents that produce a negative collector current swing during a part of ac- period. In this case, along with always-positive collector- emitter voltage, the instant dissipated power also is negative. A high-efficiency BJT power amplifier was simulated in order to demonstrate a new class features.\",\n \"Title: Design of Class-E Amplifier With MOSFET Linear Gate-to-Drain and Nonlinear Drain-to-Source Capacitances.\\nYear: 2011\\n\\nAbstract: This paper presents expressions for the waveforms and design equations to satisfy the ZVS/ZDS conditions in the class-E power amplifier, taking into account the MOSFET gate-to-drain linear parasitic capacitance and the drain-to-source nonlinear parasitic capacitance. Expressions are given for power output capability and power conversion efficiency. Design examples are presented along with the PSpi...\",\n \"Title: Experimental Results for the Small-Signal Study of the PWM Boost DC-DC converter with an integral-lead Controller.\\nYear: 1995\\n\\nAbstract: An experimental verification of previously derived small-signal low-frequency open- and closed-loop characteristics and step responses of a voltage-mode-controlled pulse-width-modulated (PWM) boost DC-DC converter is presented. The Bode plots of the voltage transfer function of the control circuit, the converter and the PWM modulator, the open-loop control-to-output and input-to-output transfer functions, the loop gain, and the closed-loop control-to-output and input-to-output transfer functions are measured. The step responses to the changes in the input voltage, the duty cycle, and the reference voltage are measured. The theoretical results were in good agreement with the measured results. The small-signal model of the converter is experimentally verified.\",\n \"Title: Waveform Equations, Output Power, and Power Conversion Efficiency for Class-E Inverter Outside Nominal Operation\\nYear: 2014\\n\\nAbstract: This paper presents analytical expressions for steady-state waveforms, output power, and power conversion efficiency for the class-E inverter outside the class-E zero-voltage switching and zero-derivative switching conditions. The analytical expressions in this paper include the MOSFET-body-diode effect. By carrying out PSpice simulations and circuit experiments, it is shown that the analytical predictions agree with the simulated and experimental results quantitatively, which indicates the validity of the analytical expressions. Additionally, the switching-pattern distribution maps are also given by using the analytical waveform equations.\",\n \"Title: Analysis of PWM Z-Source DC-DC Converter in CCM for Steady State.\\nYear: 2012\\n\\nAbstract: Steady-state analysis of pulse-width modulated (PWM) Z-source dc-dc converter operating in continuous conduction mode (CCM) is presented. Voltage and current waveforms, and their corresponding expressions describing the steady-state operation of the PWM Z-source dc-dc converter have been presented. The input-to-output dc voltage transfer functions, both for ideal and non-ideal PWM Z-source dc-dc c...\",\n \"Title: Single-Loop Current-Mode Control of a PWM Boost DC-to-DC converter with a Non-Symmetric phase Controller.\\nYear: 1995\\n\\nAbstract: An extensive small-signal analysis of a single-loop current-mode control strategy for a pulse-width-modulated (PWM) boost DC-to-DC power converter operating in continuous conduction mode (CCM) is proposed using a new non-symmetric phase controller. To model the boost power stage, a linear circuit model is used which includes all parasitic components such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor ON-resistance, and the diode forward resistance and offset voltage. A boost power stage design example gives component design equations and will serve to illustrate the closed-loop converter design. A design procedure for the new non-symmetric phase controller is presented. Open-loop and closed-loop circuit models and transfer functions are derived for the boost PWM converter and illustrated by Bode plots. An approach is presented for simplifying closed-loop transfer functions, using Euler's identity, into a format which is conducive so modeling in any high level programming language on a personal computer. Bode plots are obtained using a data analysis software package Axum 3.0 which combines a programming language, spread sheet, and publication quality technical graphics. The proposed control scheme directly controls the inductor current and indirectly controls the load current and output voltage. The closed-loop transfer functions of the proposed control scheme do not contain a right-half plane (RHP) zero, in contrast to the closed-loop transfer functions of a single-loop voltage-mode control scheme. The absence of the RHP zero provides better stability by making it easier to obtain large or specified gain and phase margins.\",\n \"Title: Design Equations For Sub-Optimum Operation Of Class E Amplifier With Nonlinear Shunt Capacitance\\nYear: 2004\\n\\nAbstract: Design equations for satisfying sub-optimum operating conditions of Class E amplifier with a nonlinear shunt capacitance with a grading coefficient of 0.5 at the duty cycle D = 0.5 are derived. By exploiting sub-optimum class E operation, various amplifier parameters such as input voltage, operating frequency, output power, and load resistance can be set as design specifications. An example of a design procedure of the class E amplifier is given. The theoretical results were verified with PSpice simulation.\",\n \"Title: Open- and Closed-Loop DC and Small-Signal Characteristics of PWM buck-Boost converter for CCM.\\nYear: 1995\\n\\nAbstract: DC and small-signal circuit models of the PWM buck-boost converter for the continuous conduction mode (CCM) are derived. The models take into account parasitic components, such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor on-resistance, and the diode forward resistance and offset voltage. The component values and the parasitics were measured for a prototype converter. The de voltage transfer function and the efficiency of the converter are derived from the de model. Small-signal open-loop transfer functions are derived from the small-signal model. The derivation of the transfer function for an integral-lead controller with the loading effect of the voltage divider network in the feedback loop is given. Small-signal closed-loop transfer functions are derived. Bode plots are given for various transfer functions of the converter.\",\n \"Title: Sub-Optimum Operation Of Class E Amplifier With Nonlinear Shunt Capacitance At Any Duty Cycle\\nYear: 2006\\n\\nAbstract: An analysis is given for sub-optimum conditions of Class E amplifier with a nonlinear shunt capacitance with a grading coefficient of 0,5 at any duty cycle. By exploiting sub-optimum class E operation, various amplifier parameters such as input voltage, operating frequency, output power, and load resistance can be set as design specifications. An example of a design procedure of the class E amplifier is given. The theoretical results were verified with Pspice simulation using SPICE MOSFET model.\",\n \"Title: Experimental Static and Dynamic Characteristics of MOS-Controlled Thyristors for Resistive Loads.\\nYear: 1995\\n\\nAbstract: Experimental results are given for a PMOS-controlled thyristor (PMCT). The static I-A-V-AK characteristics of a PMCT were measured using a programmable high power curve tracer for both forward and reverse anode-to-cathode voltage V-AK at different temperatures. The characteristics are similar to the I-D-V-D characteristics of typical p-n junction diodes. The device has a low forward voltage drop at high-current levels, e.g. V-F(AK) = 1.6 V at I-A = 200 A. The dynamic behavior of the PMCT was measured in a single switch configuration under resistive loading. The transient waveforms of anode current i(A), gate current i(G), anode-to-cathode voltage v(AK), and gate-to-anode drive voltage v(GA) were observed at turn-on and turn-off for power levels up to 5 kW. The measured turn-on time was 0.3 mu s and the measured turn-off time was 2.2 mu s. The switching power loss and the conduction power loss were 3 W and 18 W, respectively.\",\n \"Title: Cmos Zero Cross-Conduction Low-Power Driver And Power Mosfets For Integrated Synchronous Buck Converter\\nYear: 2006\\n\\nAbstract: This paper presents a circuit and a design of a CMOS zero cross-conduction low-power driver for an integrated synchronous buck converter. The circuit has a zero cross-conduction, yielding low-power dissipation and high efficiency. We used the Cadence design tool with 0.18 mu M CMOS technology to implement and verify the functionalities of the low-power buck converter driver. The design criteria of these drivers depend on the power dissipation, delay, and physical size. The DC input voltage of this design is 1.2 V, the DC output voltage is IV, the output current is 120 mA, and the maximum operating frequency is up to 100 MHz. The total size of the driver is around 140 micron(2) Plus the area of an inductor and a capacitor. The designed converter achieved the required specification, and its efficiency is up to 97.9%. This circuit is more efficient than other previous low-power buck converter drivers. The proposed circuit is better than Lee's et al. and ours recent design in terms of efficiency, speed, and layout area. The new circuit is more than 4 times smaller than Lee's circuit. The circuit can be also used in I/O pads for high-current and low-power IC applications.\",\n \"Title: Derivation of the buck-boost PWM DC-DC converter circuit topology\\nYear: 2002\\n\\nAbstract: The derivation of the buck-boost PWM DC-DC converter circuit is presented. The buck and boost converter circuits are cascaded through an inverting stage. Circuit theory and manipulation will be used to simplify the cascaded circuit into the familiar inverting buck-boost PWM DC-DC converter topology.\",\n \"Title: Integration Of Class De Inverter For On-Chip Dc-Dc Power Supplies\\nYear: 2006\\n\\nAbstract: A 12.5 mW, 500 MHz class DE power inverter was designed and simulated as an inverter part of dc-dc converters to realize a fully integrated switching power supply using a 1.2 mu m CMOS process. A 20 nH spiral inductor was used in the resonant circuit. The class DE inverter requires lower inductance than PWM buck converter. Soft switching operation enables high conversion efficiency at high operating frequencies. The class DE inverter can be an excellent candidate for on-chip switching converters because of very high efficiency, smaller passive elements, and low peak switch voltage.\",\n \"Title: Isolated Two-Transistor Zeta Converter With Reduced Transistor Voltage Stress.\\nYear: 2011\\n\\nAbstract: This brief introduces an isolated two-switch Zeta dc-dc converter, along with the steady-state analysis and experimentation. The high transistor voltage stress due to the ringing caused by the resonance of the transformer leakage inductance and the transistor output capacitance is a major drawback in the conventional isolated Zeta converter. With the incorporation of an additional transistor and t...\",\n \"Title: Active-clamp ZVS two-switch flyback converter\\nYear: 2011\\n\\nAbstract: This paper introduces a zero voltage switching (ZVS) two-switch flyback pulse-width modulated (PWM) DC-DC converter along with the principle of circuit operation and steady-state analysis. The proposed converter topology is the result of incorporating an auxiliary circuit in place of the clamping diodes on the primary side of the conventional hard- switching two-switch flyback converter, resulting in a soft- switching two-switch flyback converter with reduced switch voltage stresses. The auxiliary circuit is an active-clamp circuit made up of two switches and a clamp capacitor. The active clamp circuit recycles the energy stored in the parasitic transformer leakage inductance, facilitates the ZVS operation of all active switches, and limits the voltage stresses of all the active switches to a value less than or equal to the DC input voltage VI. Circuit description, principle of operation, steady-state analysis, and simulation results of the proposed converter are presented.\",\n \"Title: Feedforward Control With Reference Voltage Modulation\\nYear: 1999\\n\\nAbstract: A feedforward control technique with reference voltage modulation is introduced for PWM buck converter operated in the continuous conduction mode (CCM). The reference voltage is proportional to the de converter input voltage. A steady-state analysis is performed. Experimental results are given. The measured open-loop line voltage regulation was 1.32%/V.\",\n \"Title: Two-switch flyback PWM DC–DC converter in discontinuous-conduction mode\\nYear: 2011\\n\\nAbstract: The two-switch flyback DC–DC converter is an extended version of the conventional single-switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single-switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two-switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed analysis and design procedure of the diode-clamped two-switch flyback converter operated in discontinuous-conduction mode (DCM). A comparison of power losses of the two-switch and the single-switch flyback converters is given. The two-switch flyback converter was bread-boarded to validate the theoretical analysis. Experimental results from a 20-V/30-W, 100-kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright © 2010 John Wiley & Sons, Ltd.\",\n \"Title: Margins Of Stability Of Inner-Current Loop Of Peak Current-Mode Controlled Pwm Dc-Dc Converters\\nYear: 2009\\n\\nAbstract: This paper presents expressions for the limiting value of the duty cycle and the minimum value of the slope compensation for marginally stable operation as well as for the normalized crossover frequency, the maximum duty cycle, and the value of the slope compensation at a required phase margin. These quantities describe the performance of the inner-current loop in peak current-mode controlled PWAI dc-dc converters. The derivations are based on the Pade approximation of z = exp(sTs). The results of this paper can be used for the design of the inner-current loop with a specified phase margin.\",\n \"Title: Derivation of the Cuk PWM DC-DC converter circuit topology\\nYear: 2003\\n\\nAbstract: The derivation of the transformerless Cuk PWM DC-DC converter circuit is presented. Boost and buck PWM DC-DC converter circuits are cascaded through a unity-gain inverting stage. Circuit theory and manipulations I are used to simplify the cascaded circuit into the Cuk PWM DC-DC converter topology.\",\n \"Title: Two-switch flyback-forward PWM DC-DC converter with reduced switch voltage stress\\nYear: 2010\\n\\nAbstract: This paper introduces a two-switch flyback-forward pulse-width modulated (PWM) DC-DC converter along with the steady-state analysis, simplified design procedure, and experimental verification. The proposed converter topology is the result of integrating the secondary sides of the two-switch flyback and the two-switch forward converters in an anti-parallel connection, while retaining the two-main switches and the clamping diodes on a single winding primary side. The hybrid two-switch flyback-forward converter shares the semiconductor devices on the primary side and the magnetic component on the secondary side resulting in a low volume DC-DC converter with reduced switch voltage stress. Simulation and experimental results are given for a 10-V/30-W, 100 kHz laboratory prototype to verify the theoretical analysis.\",\n \"Title: Analysis and Design of Class- Power Amplifier\\nYear: 2014\\n\\nAbstract: This paper presents analytical expressions for the class-EM power amplifier, taking into account the fundamental-frequency and harmonic components of output currents in the main and auxiliary circuits. By using the proposed expressions, design values for satisfying not only the class-EM ZVS/ZDVS/ZCS/ZDCS conditions of the main circuit, but also the ZVS condition of the auxiliary circuit can be achieved without applying any tuning process. The analytical predictions agreed with experimental and PSpice-simulation results quantitatively, which showed the validity of analytical expressions given in this paper.\",\n \"Title: Design Of Class-De Amplifier With Linear And Nonlinear Shunt Capacitances For 25 % Duty Ratio\\nYear: 2009\\n\\nAbstract: The class-E ZVS/ZDS operation within the class-DE amplifier can be easily achieved by adding external shunt capacintaces. This paper presents the analytical expressions for the design of the class-DE amplifier with the shunt capacitances composed of the linear and nonlinear capacitances for the switch-on duty ratio D = 0.25. In the analysis, an equivalent linear shunt capacitance of nonlinear MOSFET output capacitance are defined and derived. The analytical results show good agreement with the experimental ones, which validates our analysis.\",\n \"Title: Static Characteristics of MOS-Controlled Thyristors - Analysis, Simulation, and Experimental Results.\\nYear: 1995\\n\\nAbstract: An equation for the i(K)-v(AK) static forward characteristic of an MOS-controlled thyristor (MCT) is derived using a four-transistor equivalent model of the device. The Ebers-Moll large-signal model is used for n-p-n and p-n-p bipolar transistors. The equation is similar to that for forward-biased diodes. The equivalent saturation current of the MCT is a function of both the saturation currents and the forward and reverse current gains of the n-p-n and p-n-p transistors. Effects of these parameters on the MCT equivalent saturation current are investigated. Voltages and currents of all transistors that form the MCT equivalent model are simulated using SPICE to explain the behavior of the device in the forward-biased region. Finally, the experimental i(K)-v(AK) characteristics are presented. The calculated and measured i(K)-v(AK) characteristics were in good agreement. The measured ON-voltage drop was 1.6 V at a cathode current of 200 A and a temperature of 300 K. MCTs are especially useful power devices for electric car applications.\",\n \"Title: Reverse Recovery of Power PN Junction diodes.\\nYear: 1995\\n\\nAbstract: A quasi-steady state approximation is used to derive expressions for the waveforms of minority carrier charge stored in p(+)nn(+) power junction diodes driven by large-signal sinusoidal and ramp voltages. These waveforms are derived by solving a diode charge-control differential equation. Using the charge waveforms, the storage time is determined and the diode current and voltage waveforms are predicted. It is shown that three frequency ranges can be distinguished: (1) low-frequency range in which the reverse recovery is negligible, (2) mid-frequency range in which the reverse recovery is detrimental, but the diode is still of practical value, and (3) high-frequency range where the diode does not exhibit its rectifying properties. A simple method for measuring the minority carrier lifetime is proposed. Experimental results are given for an MR826 East-recovery pn junction diode and a 31DQ06 Schottky diode for operating frequencies of up to 10 MHz. The theoretical and experimental results were in good agreement.\",\n \"Title: Maximum Drain Efficiency Class F-3 Rf Power Amplifier\\nYear: 2011\\n\\nAbstract: This paper presents a design procedure for the class F-3 RF power amplifier. The required range of the drain current conduction angle for the class F-3 power amplifier is specified. Additionally, an equation for the resistance of the third harmonic resonant circuit is given. Class F-3, AB, and C power amplifiers were designed and simulated to compare their respective performance in terms of efficiency.\",\n \"Title: Effect of MOSFET gate-to-drain parasitic capacitance on class-E power amplifier\\nYear: 2010\\n\\nAbstract: In this paper, we present analytical expressions for the waveforms and design equations for achieving the ZVS/ZDS conditions in the class-E power amplifier, taking into account the gate-to-drain parasitic capacitance of the MOSFET. We also give a design example along with PSpice simulation and experimental results. The voltage waveforms obtained from both the PSpice simulation and the circuit experiment achieved the class-E ZVS/ZDS conditions completely, which verify the analytical expressions. The results in this paper indicate that it is important to consider the effect of the MOSFET gate-to-drain capacitance for achieving the class E ZVS/ZDS conditions. The experimental power conversion efficiency achieved 92.8 % at output power Po = 4.06 W and operating frequency f = 7 MHz.\",\n \"Title: Loop gain of the common-gate Colpitts oscillator\\nYear: 2011\\n\\nAbstract: This study presents the derivations of the voltage transfer functions of the amplifier A, the feedback network β, the loop gain T, the closed-loop gain Af and also the characteristic equation for the common-gate (CG) Colpitts oscillator, using the small-signal model of the metal-oxide-semiconductor field-effect transistor (MOSFET) CG Colpitts oscillator. Using the characteristic equation, the expressions for the oscillation frequency of the sinusoidal output voltage and the condition for oscillation in steady state are derived. The characteristic equation is also used to obtain a plot of trajectories of the closed-loop poles of the CG Colpitts oscillator by varying the MOSFET small-signal transconductance gm. The locations of the complex conjugate poles of closed-loop gain that depict the starting and steady-state conditions for oscillations are presented. Nyquist plots of the loop gain are given to illustrate the startup and steady-state conditions of oscillations. Simulation and experimental results to verify the theory are also given.\",\n \"Title: Design Equations For Off-Nominal Operation Of Class E Amplifier With Nonlinear Shunt Capacitance At D=0.5\\nYear: 2013\\n\\nAbstract: Design equations for satisfying off-nominal operating conditions of the class E amplifier with a nonlinear shunt capacitance for a grading coefficient of 0.5 and the duty cycle D = 0.5 are derived. By exploiting the off-nominal class E operation, various amplifier parameters such as input voltage, operating frequency, output power, and load resistance can be set as design specifications. As a result of the analysis in this paper, the following extension of the usability of the class E amplifier was achieved. With rising up the de supply voltage, the shunt capacitance which achieves the off-nominal operation can be increased. This means that a transistor with higher output capacitance can be used for ZVS operation. This also means that maximum operating frequency which achieves ZVS can be increased. An example of a design procedure of the class E amplifier is given. The theoretical results were verified with an experiment.\",\n \"Title: Output Characteristics Of Class E Amplifier With Nonlinear Shunt Capacitance Versus Supply Voltage\\nYear: 2007\\n\\nAbstract: Due to the nonlinearity of shunt capacitance of the class E amplifier, the output amplitude of the class E amplifier is not a linear function of the dc supply voltage of the class E amplifier. Estimating this nonlinearity is important to maintain ZVS operation in a situation of variable dc supply voltage, e.g., for a amplitude modulated (AM) power amplifier. However, there are no research results for the output amplitude of class E amplifier with nonlinear shunt capacitance. In this paper, the circuit behavior of the class E amplifier with nonlinear shunt capacitance outside designed nominal conditions is obtained using mathematical processing software MathCAD.\",\n \"Title: Generalized Design Considerations and Analysis of Class-E Amplifier for Sinusoidal and Square Input Voltage Waveforms\\nYear: 2015\\n\\nAbstract: In this paper, analytical expressions and design equations are presented for a class-E amplifier with MOSFET nonlinear drain-source capacitance and linear gate-drain parasitic capacitance, along with external linear shunt capacitance. The class-E amplifier characteristics are presented as functions of the ratio of the sum of the external linear shunt capacitance and the MOSFET linear gate-drain capacitance to the MOSFET drain-source junction capacitance when the switch voltage is zero. Although the effect of the MOSFET linear gate-drain capacitance is similar to that of the external linear shunt capacitance on the design of the class-E amplifier with a square input voltage, the difference between their effects should be considered for the sinusoidal input voltage, which is one of the most important suggestions in this paper. Additionally, analytical expressions of the output power capability is given, which is considerably affected by the external linear shunt capacitance. Two design examples are presented, taking into account as design specification the output power of 8.7 W and the operating frequency of 4 MHz, along with the PSpice-simulations and experimental waveforms.\",\n \"Title: Closed-Loop Characteristics of voltage-Mode-Controlled PWM Boost DC-DC converter with an integral-lead Controller.\\nYear: 1994\\n\\nAbstract: A complete analysis of a voltage-mode-controlled pulse-width-modulated (PWM) boost DC-DC power converter is presented using a previously derived small-signal model for continuous conduction mode (CCM). All parasitic components such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor on-resistance, and the diode forward resistance and offset voltage are included in the model. A design procedure for an integral-lead controller including the loading effect of the voltage divider in the feedback loop is given. The Bode plots of the closed-loop control-to-output transfer function, input-to-output transfer function, input impedance, and output impedance are determined and illustrated for three values of the duty cycle. Step response plots of the PWM boost converter in the open-loop and closed-loop cases are shown for changes in line voltage and duty cycle.\",\n \"Title: Dynamic Performance of MCTS under Inductive Load conditions.\\nYear: 1994\\n\\nAbstract: PMOS-controlled thyristors (PMCTs) were tested in a single-switch configuration under inductive-load hard-switching conditions. The transient current and voltage waveforms during the turn-on and turn-off transitions were observed for 50 A/1000 V devices. The experimental waveforms are given for the anode current, the inductor current, the anode-to-cathode voltage, and the gate-to-anode drive voltage. These waveforms were obtained for periodic gate drive voltage at 6.5 kHz. The test circuit was operated at power levels of up to 370 W. The measured turn-on time was 0.255 mus at an anode-to-cathode voltage of 270 V and the measured turn-off time was 1.6 mus at an anode current of 16 A. The measured storage time was 1 mus. The measured input capacitance of the MCT was 13.5 nF and the output capacitance was 66.7 nF. It was found that the input and output capacitances of PMCTs are approximately linear.\",\n \"Title: Analysis Of Dynamic And Transient Response Of Frequency Modulated Class E Amplifier\\nYear: 2014\\n\\nAbstract: The dynamic characteristics of the class E power amplifier with frequency modulation are derived. Such an analysis is essential for designing amplitude and frequency modulated amplifier systems such as an EER scheme. Conventionally, an analytical expression for the frequency response of a frequency modulated class E amplifier has not been derived yet. This omission is rectified here by modeling the circuit with both a low-frequency model and a high-frequency model. Further, a time domain waveform is derived from the frequency domain transfer function for some typical time varying drive signals. The analytical results for the frequency response of a 1-MHz class E amplifier are shown to match PSpice simulations and measured values well.\",\n \"Title: Multiphase resonant inverters with common resonant circuit\\nYear: 2014\\n\\nAbstract: A new family of Class D resonant inverters is proposed in this paper. Multiple identical series resonant inverters are paralleled using intercell transformers to form phase-controlled multiphase resonant inverter with a common resonant circuit. Inverters can operate at constant frequency utilizing phase-shift control to regulate output. A frequency-domain analysis of the proposed family is performed. An experimental prototype of a three-phase resonant inverter with common resonant circuit was built and extensively tested at an output power of 550 W and switching frequency of 167 kHz.\",\n \"Title: Analytical design procedure for resonant inductively coupled wireless power transfer system with class-E2 DC-DC converter\\nYear: 2014\\n\\nAbstract: This paper presents a resonant inductive coupling wireless power transfer (RIC-WPT) system with a class-E2 dc-dc converter along with its analytical design procedure. By using the class-E inverter as a transmitter and the class-E rectifier as a receiver, the designed WPT system can achieve a high power-conversion efficiency because of the class-E ZVS/ZDS conditions satisfied in both the inverter and the rectifier. In the simulation results, the system achieved 65.9 % overall efficiency at 5 W (50 Ω) output power, coil distance 30 cm, and 5 MHz operating frequency. Additionally, the simulation results showed good agreement with the design specifications, which indicates the validity of the design procedure.\",\n \"Title: Modeling and Analysis of Class-E Amplifier With a Shunt Inductor at Sub-Nominal Operation for Any Duty Ratio\\nYear: 2014\\n\\nAbstract: This paper presents analytical expressions for the sub-nominal operation, which is only the zero current switching (ZCS) condition, of the class-E power amplifier with a shunt inductor at any duty ratio. The duty ratio is considered not only as a design specification but also as an adjustment parameter. In the sub-nominal operation with any duty ratio, both the peak switch voltage and the peak switch current can be set as design specifications due to two more degrees of design freedom in comparison with the class-E nominal amplifier at the fixed duty ratio. Additionally, it is also seen that the duty ratio affects the maximum operating frequency and the output power capability with ZCS condition. A design example of the class-E ZCS amplifier with a shunt inductor under the specifications of peak switch voltage and peak switch current is given. The measurement and a simulation by circuit simulator results agreed with the analytical expressions quantitatively, which show the validity of our analytical expressions.\",\n \"Title: Voltage-clamped class E amplifier with a Zener diode across the switch\\nYear: 2002\\n\\nAbstract: The class E amplifier with a clamped switch peak voltage using a Zener diode is proposed and analyzed A higher output power is obtained when the maximum switch voltage is clamped. Design equations are derived for the output power and power losses. The effect of the Zener diode on the switch voltage waveform, output power, and efficiency are examined. The experimental verification is presented using a prototype circuit.\",\n \"Title: A method for predicting the ZVS condition for the class E amplifier\\nYear: 2002\\n\\nAbstract: A method for predicting the ZVS condition before turning the switch on is presented for the class E amplifier operating with D=0.5. The prediction is obtained in real- time by observing the switch current waveform and the shunt capacitor current waveform with a simple analog- digital circuit. Using this method, a control circuit that ensures ZVS condition becomes feasible.\",\n \"Title: Class-E MOSFET low-voltage power oscillator\\nYear: 2002\\n\\nAbstract: A class-E oscillator based on the Motorola MTP3055E power MOSFET was analyzed, designed, built, and tested. The supply voltage was 4.5 V, while the output power was 1 W. The oscillator feedback network per- mits the use of MOSFETs with a high gate-source volt- age. The efficiency and output power versus frequency, and the frequency versus the voltage supply were measured.\",\n \"Title: Voltage-clamped class E amplifier with a Zener diode across the choke coil\\nYear: 2002\\n\\nAbstract: A class E amplifier with a clamped switch peak voltage with a Zener diode across the choke inductor is proposed and analyzed. Power loss in the Zener diode is reduced to 2/3 of that in the amplifier with a Zener diode across the switch. The effect of the Zener diode on the switch voltage waveform, output power, and efficiency are examined and experimentally verified.\",\n \"Title: Impact of boost converter parameters on open-loop dynamic performance for DCM\\nYear: 2002\\n\\nAbstract: The impact of a PWM DC-DC boost converter parameters on its open-loop dynamic performance is studied. The parameters considered are: the load resistance R, the filter capacitor ESR rC, and the inductor ESR r. The principle of energy conservation approach is used to take into account parasitic resistances of the transistor and diode in the inductor ESR. The parameter impact has been evaluated by using a small-signal circuit model composed of current-controlled current sources. Bode plots of the control-to-output transfer function are given using R, rC, and r as parameters. Plots of poles and zeros are given as functions of these three resistances. These plots clearly show how the dynamic performance of the boost converter is affected by these parameters.\",\n \"Title: High-efficiency microwave BJT power amplifier simulation\\nYear: 2002\\n\\nAbstract: Simulation results of a Siemens BFP490 BJT power amplifier for a frequency range 8-11 GHz are presented. It was shown that the output network input impedance is inductive and the collector current is negative during a part of the AC cycle, when the amplifier operates in high-efficiency mode.\",\n \"Title: Feasibility study of on-chip class E DC-DC converter\\nYear: 2003\\n\\nAbstract: A 200 mW, 800 MHz class E DC-DC converter is designed using a 0.6 μm CMOS process and then simulated. A 22 nH spiral inductor is used in the resonant circuit. An integrated feedback controller with a VCO is used for the output voltage regulation. It is shown that the class E inverter is an excellent candidate for on-chip switching converters because of very high efficiency, and the inductor can be minimized at high operating frequencies. The simulated converter efficiency was 72% at 4.5 V output voltage, 200 mW output power, and 800 MHz switching frequency.\",\n \"Title: Voltage-clamped class E amplifier with transmission-line transformer\\nYear: 2005\\n\\nAbstract: A high switch peak voltage is a disadvantage of the class E amplifier in some applications. A lossless voltage clamp method with a transformer and a diode has been proposed as a remedy for the high peak switch voltage. However, this circuit suffers from a large ringing due to the transformer leakage inductance, which is superimposed on the clamped voltage and partially eliminates the effect of the voltage clamping. In this paper, a switch voltage clamping using a transmission-line transformer is proposed to reduce the ringing. The proposed concept was verified with an experimental voltage-clamped class E amplifier at 4 MHz and 2.9 W.\",\n \"Title: DC and AC analysis of buck PWM DC-DC converter with peak-voltage-modulation feedforward control\\nYear: 1999\\n\\nAbstract: DC and small-signal analyses are given for the open-loop buck pulse-width modulation (PWM) DC-DC converter with peak-voltage-modulation (PVM) feedforward control. A DC model is used to derive DC input-to-output transfer function taking into account parasitic components, such as the MOSFET on-resistance, diode forward resistance, and diode offset voltage. A small-signal model is used to derive the audiosusceptibility. It is shown that ideally the audiosusceptibility is zero for the buck converter with PVM feedforward control\",\n \"Title: Power losses and efficiency of class E RF power amplifiers at any duty cycle\\nYear: 2001\\n\\nAbstract: Class E RF power amplifiers offer very high efficiency with relatively few components. Component values used in class E circuit design are directly dependent upon the selection of duty cycle. This paper presents an analysis of the effect of duty cycle on power loss in each of the components and total efficiency, and includes experimental results\",\n \"Title: Buck PWM DC-DC converter with reference-voltage-modulation feedforward control\\nYear: 2001\\n\\nAbstract: DC and small-signal analyses are given for the open-loop buck pulse-width modulated (PWM) DC-DC converter with reference-voltage-modulation (RVM) feedforward control. A DC model is used to derive DC input-to-output transfer function taking into account parasitic components, such as the MOSFET on-resistance, diode forward resistance, and diode offset voltage. A small-signal model is used to derive the audiosusceptibility and input impedance\",\n \"Title: Eddy-current power loss in laminated iron cores\\nYear: 2001\\n\\nAbstract: This paper presents an analysis of power losses in gapless laminated iron cores at high frequencies. First, the magnetic field intensity is found. Next, the eddy current density is determined. Finally, expressions for the power loss density and the power loss per unit volume of an iron core are derived\",\n \"Title: Low-voltage self-oscillating class E electronic ballast for fluorescent lamps\\nYear: 2006\\n\\nAbstract: In this paper, electronic ballast based on the class E oscillator with a capacitive impedance inverter is presented. The ballast allows us to supply an instant-start fluorescent lamp from a 12 V dc power source. The class E oscillator allows for increasing the efficiency using a simple structure with only one switch without a driving circuit. Due to the anti-parallel diode integrated into the switch, the ZVS condition is satisfied in the ignition mode, maintaining high efficiency. One of the applications of the ballast is mobile equipment, where compact independent power sources are used, for example, batteries or solar cells. The ballast was designed with the following parameters: VDD = 12 V, Po = 18 W, fo = 440 kHz. The measured efficiency was 83%, the output power was 18.5 W, and the dc supply power was 22.3 W at the operating frequency of 444.44 kHz\",\n \"Title: Off-Nominal Operation of Class-E Amplifier at Any Duty Ratio\\nYear: 2007\\n\\nAbstract: Design equations for satisfying the suboptimum operating condition, i.e., only the zero-voltage switching (ZVS) condition, of a class-E amplifier with a linear shunt capacitance at any duty ratio are derived. By exploiting the suboptimum class-E operation, various amplifier parameters such as operating frequency, output power, load resistance, and component values can vary, while the ZVS operation and high efficiency can be achieved. An example of a design procedure of the class-E amplifier is given. The theoretical results were verified with PSpice simulation and an experiment.\",\n \"Title: ZVS operating frequency versus duty ratio of class E amplifier with nonlinear shunt capacitance\\nYear: 2008\\n\\nAbstract: The maximum operating frequency of the class E amplifier with nonlinear shunt capacitance depends on the transistor duty ratio. It varies with the duty ratio under zero- voltage switching (ZVS) and zero-derivative switching (ZDS) conditions at fixed values of the output power, dc supply voltage. Therefore, the design of the class E amplifier with given values of the shunt capacitance, the output power, dc supply voltage is possible by adjusting the operating frequency. The operating frequency has the maximum value when the duty ratio DON is approximately 0.36 at VDD/Vbi = 1 . It is also shown that the maximum operating frequency is higher when the dc supply voltage VDD is lower.\",\n \"Title: Maximum Operating Frequency of Class-E Amplifier at Any Duty Ratio\\nYear: 2008\\n\\nAbstract: This paper shows that the maximum operating frequency of the class-E power amplifier depends on the transistor duty ratio. The maximum operating frequency increases as the duty ratio decreases under zero-voltage switching and zero-derivative switching conditions at fixed values of the output power, dc supply voltage, and shunt capacitance.\",\n \"Title: Analysis of dynamic frequency response of class E amplifier\\nYear: 2009\\n\\nAbstract: A dynamic response of the output voltage to the input supply voltage VDD of a class E amplifier is derived with modeling the circuit by a low-frequency model and a high-frequency model. If the perturbation frequency is much lower than the switching frequency, the state-space averaging model of the class E amplifier can be approximated as a single-pole low-pass filter composed of the choke inductance LRFC and the parallel combination of the switch resistance and the shunt capacitor resistance. The analysis in this paper is based on the steady-state behavior outside the designed conditions given in. Hence, the derivation is applicable even if the class E amplifier is operated in off-tuned conditions. The analytical results for the frequency response of a 1 MHz class E amplifier matched well with Pspice simulations at the perturbation frequency less than 100 kHz.\",\n \"Title: Power efficiency calculation of class E amplifier with nonlinear shunt capacitance\\nYear: 2010\\n\\nAbstract: Power efficiency of a class E RF power amplifier versus dc supply voltage VDD when the shunt capacitance of the class E amplifier is a nonlinear capacitance with the grading coefficient m = 0.5 is obtained. In the calculation of power efficiency, switching loss due to non-zero turning on of the MOSFET, power loss due to forward voltage drop of the MOSFET body diode, and power loss due to MOSFET on-resistance are incorporated. It is found that the highest power efficiency is obtained at a lower dc supply voltage than the designed dc supply voltage, even though the circuit was designed to achieve the nominal operation at the designed dc supply voltage. The calculation was performed with Mathcad programming and the results were verified with Pspice simulations.\",\n \"Title: Control-to-output and duty ratio-to-inductor current transfer functions of peak current-mode controlled dc-dc PWM buck converter in CCM\\nYear: 2010\\n\\nAbstract: The control-to-output and the duty ratio-to-inductor current transfer functions of peak current-mode controlled PWM dc-dc buck converter in CCM are derived and illustrated. The closed inner-current loop and the power stage inductor current-to-output voltage transfer functions are used to derive the control-to-output transfer function of the peak current-mode controlled buck converter in CCM, which is essential for the outer-voltage loop controller design. A small-signal model including parasitic components and delay is used to derive the power stage transfer function, necessary for proper analysis of the power stage. The loop gain of the inner-current loop is derived and is shown that it is independent of converter topology.\",\n \"Title: Comparison of Wide- and High-Frequency Duty-Ratio-to-Inductor-Current Transfer Functions of DC–DC PWM Buck Converter in CCM\\nYear: 2012\\n\\nAbstract: Wide- (WF) and high-frequency (HF) small-signal models are presented for pulsewidth-modulated dc-dc buck converter power stage. An exact duty-ratio-to-inductor-current transfer function is derived using the WF model and compared to an approximate transfer function derived using the HF model for the buck converter power stage in continuous conduction mode. The theoretical results are validated using experimental results.\",\n \"Title: Small-signal modeling of PWM Z-source converter by circuit-averaging technique\\nYear: 2011\\n\\nAbstract: This paper presents the small-signal modeling of pulse-width modulated (PWM) Z-source converter (ZSC) operating in continuous conduction mode (CCM) by circuit averaging technique. The averaged large-signal, dc, and time-invariant linear small-signal circuit models of PWM ZSC power stage operating in CCM are derived. The small-signal modeling focuses on the dynamics introduced by the Z network present in the ZSC. Based on the small-signal model derived, the small-signal model required to derive the open-loop input-to-capacitor voltage transfer function is derived. The open-loop input-to-capacitor voltage transfer function is derived, and the associated theoretical Bode plots are illustrated using Matlab and is verified by circuit simulation. The theoretical results were in excellent agreement with the simulation results, validating the ac small-signal model and the derived input-to-capacitor voltage transfer function.\",\n \"Title: Power conversion efficiency of class-E power amplifier outside nominal operation\\nYear: 2011\\n\\nAbstract: This paper gives analytical expressions for the output power and the power conversion efficiency of the class-E power amplifier outside the class-E ZVS/ZDS switching conditions. The analytical predictions agreed with the experimental results quantitatively, which indicates the validity of the analytical expressions. Moreover, a design example applying the analytical expressions for the power conversion efficiency is given. By using the analytical expressions, it is possible to design the class-E amplifier, which improves the power conversion efficiency compared with that of the class-E amplifier satisfying the class-E ZVS/ZDS conditions.\",\n \"Title: Analysis of Class-DE Amplifier With Linear and Nonlinear Shunt Capacitances at 25% Duty Ratio\\nYear: 2010\\n\\nAbstract: The class-E zero-voltage switching/zero-derivative switching operation within class-DE amplifiers can be easily achieved by adding external shunt capacitances. This paper gives the analytical expressions for the designs of the class-DE amplifiers with the shunt capacitances composed of linear and nonlinear capacitances for any grading coefficient m of MOSFET body junction diodes at the switch-on duty ratio D = 0.25. In the analysis, an equivalent linear shunt capacitance of the nonlinear MOSFET drain-source parasitic capacitances is derived. Analytical results show good agreements with the simulation and experimental ones, which validate our analysis.\",\n \"Title: Power Losses and Efficiency of Class-E Power Amplifier at Any Duty Ratio\\nYear: 2004\\n\\nAbstract: This paper presents an analysis of the effect of duty ratio on power loss and efficiency of the Class-E amplifier. Conduction loss for each Class-E circuit component is derived and total amplifier losses and efficiency are expressed as functions of duty ratio. Two identical 300-W Class-E amplifiers operating at 7.29 MHz are designed, constructed, and tested in the laboratory. Dependence of total e...\",\n \"Title: Frequency-Dependent Resistance Of Litz-Wire Square Solenoid Coils And Quality Factor Optimization For Wireless Power Transfer\\nYear: 2016\\n\\nAbstract: In order to achieve the highest efficiency of wireless power transfer (WPT) systems, the quality factor of the resonant coil should be as high as possible. Due to the skin effect and the proximity effect, the coil resistance increases with the increase in the frequency. The highest quality factor exists for the optimal frequency together with the corresponding frequency-dependent inductor resistance. This paper employs the Biot-Savart law to calculate the magnetic field strength, which results in the proximity-effect resistance in single-layer litz-wire square solenoid coils without a magnetic core. A strand-number coefficient is introduced to reflect the influence of the strand number inside the wire bundle on the proximity-effect resistance. The coefficient is obtained through simple inductor resistance measurements for various numbers of litz-wire strands. The optimal frequency for the highest quality factor is derived based on the resistance evaluation. Several prototype coils were manufactured to verify the resistance analysis. Two 50 cm x 50 cm square coils were employed to construct a WPT prototype. The maximum dc-dc efficiency of this WPT was about 75% at 100-cm distance.\",\n \"Title: Small-signal modeling of the PWM boost DC-DC converter at boundary-conduction mode by circuit averaging technique\\nYear: 2015\\n\\nAbstract: This paper presents the derivation of the small-signal model of the boost converter operating in the boundary-conduction mode (BCM) using the circuit averaging technique. The essential transfer functions such as the input-to-output voltage transfer function M\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">v</inf>\\n and the control-to-output transfer function T\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">p</inf>\\n are derived using the linear small-signal model. Further, the characteristics of these transfer functions are analyzed using a representative design example. The switching circuit and the small-signal model are tested on a simulator to validate the proposed model.\",\n \"Title: Transfer functions of a transformer at different values of coupling coefficient.\\nYear: 2016\\n\\nAbstract: The low- and mid-frequency model of the transformer with resistive load is analysed for different values of coupling coefficients. The model comprising of coupling-dependent inductances is used to derive the following characteristics: voltage gain, current gain, bandwidth, input impedance, and transformer efficiency. It is shown that in the low- and mid-frequency range, the turns ratio between the...\",\n \"Title: Analysis and design of class E power amplifier considering MOSFET parasitic input and output capacitances.\\nYear: 2016\\n\\nAbstract: In this study, design theory and analysis for the class E power amplifier (PA), considering the metal oxide semiconductor field effect transistor (MOSFET) parasitic input and output capacitances, are proposed. The input resistance and capacitances cause non-ideal input voltage at gate terminal, which affect the specifications of the class E PA. In the proposed study, non-linear drain-to-source, li...\",\n \"Title: Sensitivity of effective relative permeability for gapped magnetic cores with fringing effect.\\nYear: 2017\\n\\nAbstract: Magnetic component tolerances are caused by variations in air-gap and core relative permeability. This study presents the derivation for sensitivity of effective relative permeability to variations in the relative core permeability and relative gap length for magnetic cores with and without fringing effect. The expressions for the fringing factor and effective relative permeability for the magneti...\",\n \"Title: High switching frequency performance of E-GaN FETs and silicon MOSFETs.\\nYear: 2017\\n\\nAbstract: This paper aims at achieving the following objectives: (a) evaluate and compare the power loss during switching transitions in the gallium nitride (GaN) FETs and silicon (Si) MOSFETs, (b) determine the frequency capability of the GaN and Si transistors, when used in hard-switching power electronic circuits, and (c) evaluate the power-performance of the synchronous buck (SB) dc-dc power converters employing GaN and Si transistors operating at different switching frequencies. The GaN transistors in EPC9037 switching network module are considered as the benchmark devices and their properties are compared with the silicon n-channel transistors with identical voltage and current ratings. Simulation results are provided for the SB converter illustrating the switching frequency limitation of the Si MOSFETs and the extended frequency capability of GaN FETS. Experimental results are provided to validate the analytical predictions.\",\n \"Title: Analysis and Design of Choke Inductors for Switched-Mode Power Inverters.\\nYear: 2018\\n\\nAbstract: This paper presents the design, analytical estimation of power losses, and experimental measurement of choke inductors for switched-mode power inverters. The described approach is applicable to a wide variety of circuits such as Class-E inverters and converters. The expressions required to design the magnetic core in the choke inductor using the area-product (Ap) method are given. The equations fo...\",\n \"Title: Dc Analysis And Design Of A Pwm Buck Converter Operated As A Dynamic Power Supply\\nYear: 2017\\n\\nAbstract: Modern energy transmission and signal reproduction techniques rely upon power amplifiers that must operate with high efficiency. An increasingly popular technique for addressing this problem involves replacing the fixed power amplifier supply voltage V-DD with a controlled, variable voltage provided by a dynamic power supply. Although pulse-width modulated dc-dc buck converters typically function as fixed-output supplies, this paper provides new theoretical dc analysis for operation wherein the output voltage is controlled and continuously variable over a wide range. A design procedure for the variable-output buck converter is derived. Key device parameters affecting converter speed and efficiency are identified. The dc analysis and design procedure are verified experimentally, with calculated and measured parameters shown to be in good agreement. Copyright (c) 2016 John Wiley & Sons, Ltd.\",\n \"Title: Analytical Optimization Of Solid-Round-Wire Windings\\nYear: 2013\\n\\nAbstract: In this paper, an analytical optimization of solid-round-wire windings conducting sinusoidal current is performed. New closed-form analytical equations are derived for the normalized solid-round-wire diameter to achieve minimum ac winding losses for sinusoidal current. Approximations of Dowell's equation are used to derive expressions for normalized diameter at the local minimum of winding ac resistance and normalized critical diameter. An equation for the winding ac resistance at the local minimum is derived. Additionally, equations for the normalized diameter at the local maximum of ac resistance and the normalized boundary diameter between low-and medium-frequency ranges are given. The formulas enable inductor and transformer designers to minimize winding loss without utilizing finite-element method analysis. Experimental verification of the presented theory is given.\",\n \"Title: Subnominal Operation of Class-E Nonlinear Shunt Capacitance Power Amplifier at Any Duty Ratio and Grading Coefficient.\\nYear: 2018\\n\\nAbstract: This paper presents an analytical model to design a class-E power amplifier under only zero-voltage-switching (ZVS) term with the MOSFET nonlinear drain-source shunt parasitic capacitance that is named as the subnominal operation. The presented analysis is performed under any grading coefficient m of MOSFET body junction diode and any duty ratio D. The grading coefficient m along with the switchin...\",\n \"Title: Zero-Voltage Switching Operation of Transformer Class-E Inverter at Any Coupling Coefficient.\\nYear: 2019\\n\\nAbstract: This paper presents a complete design methodology of a Class-E inverter with a loosely coupled transformer under zero-voltage switching conditions. At a selected maximum coupling coefficient, the inverter satisfies both zero-voltage switching (ZVS) and zero-derivative switching (ZDS) conditions to achieve a high efficiency. As the coupling coefficient is decreased from its maximum value to zero, t...\",\n \"Title: MLMVNNN for Parameter Fault Detection in PWM DC-DC Converters and Its Applications for Buck and Boost DC-DC Converters.\\nYear: 2019\\n\\nAbstract: This paper presents an effective approach to the fault diagnosis of pulsewidth modulated (PWM) DC-DC power converters. It is based on a multilayer multivalued neuron neural network with a complex QR decomposition. This network is used to identify the parameter values running out of tolerance range in two topologies of PWM DC-DC converters, namely, the buck and boost circuits. The proposed techniqu...\",\n \"Title: Nonlinear Modelling And Control Of Pwm Dc-Dc Buck-Boost Converter For Ccm\\nYear: 2018\\n\\nAbstract: In this paper, a nonlinear model of inverting pulse-width-modulated buck-boost converter for continuous conduction mode is introduced based on the large-signal averaging technique. The simulation of the nonlinear buck-boost model is performed in MATLAB/SIMULINK and compared with the corresponding circuit in SaberRD simulator for validation purpose. Additionally, a nonlinear control scheme of cascaded proportional-integral sliding-mode current controller is designed. The equivalent control law, existence, and stability conditions are introduced. The simulation results show that the proposed control system enhances the regulation performance, removes the steady-state error, and provides robust tracking against large disturbances.\",\n \"Title: High-Frequency Single-Switch Zvs Inverter For Driving Capacitive Loads\\nYear: 2018\\n\\nAbstract: This paper introduces a new switched-mode ZVS inverter that is suited to operate at high frequencies with rapid transitions. This topology includes small passive storage elements, low-voltage stress, and fast dynamic response. The single-switch inverter, which has a ground-ended transistor, can be implemented to achieve zero-voltage switching at switching frequencies of several MHz. A tuned resonant network is utilized to alleviate switch voltage stress. The resonant network, which has the desired drain-source impedance, shapes the switch voltage into a quasi-rectangular waveform. The principle of operation, design procedure, and power loss analysis of the proposed circuit are given. The new circuit prototype is designed, simulated, and built at 20 MHz. The performance of the topology is also demonstrated via experimental results. The proposed circuit can be used as a gate-drive circuit for high frequency applications.\",\n \"Title: Averaged Small-Signal Model of PWM DC-DC Converters in CCM Including Switching Power Loss.\\nYear: 2019\\n\\nAbstract: This brief proposes an improved averaged small-signal model of pulse-width modulated dc-dc power converters operated in continuous-conduction mode, which includes a resistance that corresponds to the switching power loss. Through this model, the switching power loss can be incorporated into existing averaged small-signal dynamic models. The proposed approach is based on the principle of conservation of energy. The expressions for the equivalent switching-loss resistance for the basic converter topologies are derived. The improved dc and small-signal models of the switching network are given. A boost dc-dc converter is considered as an example. The effect of the switching-loss resistance on the small-signal control-to-output transfer function is shown. Experimental results are given and the theoretical predictions have been validated.\",\n \"Title: Fault detection of resonant inverters for wireless power transmission using MLMVNN\\nYear: 2016\\n\\nAbstract: An effective approach, based on neural networks, to the fault diagnosis of dc-ac resonant inverters is presented. A MultiLayer MultiValued Neuron neural Network (MLMVNN) with a complex QR-decomposition is used to identify parameter value changing (i.e. fault detection) on a Class-E resonant inverter through steady state measurements of voltages and currents.\",\n \"Title: Fault detection in Class-E 2 resonant converters\\nYear: 2017\\n\\nAbstract: DC-DC converter reliability is of primary interest due to their key role in electronic systems. This paper proposes a diagnostic algorithm, which can be easily implemented in digital programmable device for MOSFET fault detection and identification. An improvement over the existing technique is presented, and its rapid fault detection capability is demonstrated. The two basic faults, namely the short circuit (SCF) and the open circuit fault (OCF) are identified by analyzing the current through the choke inductance. Upon identification of the fault signature, techniques to mitigate the after-effects are discussed. To validate the algorithm, a simulation on a Class-E 2 resonant converter is presented.\",\n \"Title: Design of zero-voltage-ripple buck dc-dc converter\\nYear: 2017\\n\\nAbstract: This paper presents the design of a zero-voltage-ripple (ZVR) buck dc-dc converter. The circuit uses an auto-transformer for ripple cancellation in the output voltage. The principle of operation is discussed in brief. The relationship between the currents through the magnetizing inductance and the auto-transformer windings is developed. The auxiliary inductance for ripple cancellation in series with the secondary winding is determined. The expression for the auxiliary inductance is derived. A laboratory prototype of a buck converter with supply voltage 12 V, output voltage voltage 5 V, switching frequency 500 kHz, and output power 10 W was built. Simulation and experimental results are provided validating the theoretical predictions.\",\n \"Title: Semiconductor losses of PWM buck DC-AC converter operated as dynamic power supply\\nYear: 2017\\n\\nAbstract: This paper presents a method for calculating the semiconductor losses in asynchronous and synchronous PWM buck converters when operated as a fixed-VI, fixed-RL, variable-Vo dynamic power supply. Equations are derived for MOSFET switching and conduction losses in both circuits, as well as diode conduction and forward-voltage losses. This work also compares the two topologies from the perspective of semiconductor losses to determine which circuit is inherently more efficient. The low-side MOSFET of the synchronous converter is shown via analysis and simulation to contribute the most significant power loss, thus demonstrating the asynchronous dc-ac converter topology is generally more efficient if designs are otherwise comparable.\",\n \"Title: Audio-susceptibility of inner loop of true-average current-mode controlled buck dc-dc converter\\nYear: 2017\\n\\nAbstract: The audio-susceptibility of the average current-mode controlled buck dc-dc converter in continuous-conduction mode is presented in this paper. The average current-mode control scheme used in this paper regulates the true average component of the sensed inductor current and is not affected by a high inductor current ripple at low duty ratios. The principle of negative feedback for converters with the average current-mode control is discussed in brief. The input voltage-to- inductor current disturbance transfer function is derived using the averaged, linear small-signal model. The loop gain transfer function has been analyzed to satisfy the closed-loop requirements. The closed-inner-loop input voltage-to-inductor current transfer function and the closed-inner-loop input-to-output voltage transfer functions are determined. An example buck converter is used and the characteristics are analyzed in detail. Simulation results are presented for the designed buck converter validating the theoretical predictions.\",\n \"Title: Reliability analysis and electrical characterization of a Class-E resonant inverter\\nYear: 2018\\n\\nAbstract: One of the most interesting challenges in power electronics is increasing the circuit reliability. This can be achieved by reducing the power losses and, therefore, increasing the power conversion efficiency. Conduction and switching losses in power MOSFETs are the major contributions to the converter overall power loss, which becomes a serious problem in high-power conversion applications. Resonant converters, which represent an interesting solution to reduce switching losses, are based on a resonant tank composed of inductors and capacitors tuned to resonate at a specific frequency. The resonance forms the voltage and/or current waveforms so that, under optimal conditions, the MOSFET turns on at zero-voltage switching (ZVS) and zero-derivative switching (ZCS). This drastically reduces the switching losses. Also, new semiconductor materials such as SiC or GaN are capable to operate at an increased switching frequency and reduced both conduction and switching losses. In this paper, the reliability of a Class-E resonant inverter is analyzed to identify the most critical elements of the circuit. The reliability prediction has been carried out based on MIL-HDBK-217 handbook. The Mean Time Between Failures (MTBF) and the failure rate λp are derived. Voltage and current values of all components utilized in this analysis are based on data achieved by experimental results.\",\n \"Title: Design and Characterization of Single-Layer Solenoid Air-Core Inductors\\nYear: 2019\\n\\nAbstract: This study presents the design and experimental characterisation of single-layer solenoid air-core inductors. The analytical expressions for the winding inductance, self-capacitance, and winding resistance are derived. The inductor properties are analysed up to the first self-resonant frequency. The procedure to design air-core inductors for high-frequency (HF) applications is provided. Experiment...\",\n \"Title: Analysis of Class-DE PA Using MOSFET Devices With Non-Equally Grading Coefficient\\nYear: 2019\\n\\nAbstract: The design and analysis of a new operation-mode of the class-DE power amplifier (PA) using two MOSFETs with the non-equal grading coefficient is introduced. The PA uses the optimum shunt capacitance for each MOSFET to achieve zero voltage switching (ZVS) condition and wide range for the load-resistance point of view. As compared with the conventional class-DE PA, this configuration has low value o...\",\n \"Title: A Novel Design Methodology For Extended Continuous Class-F Power Amplifiers In Wireless Applications\\nYear: 2021\\n\\nAbstract: In this paper, an extended continuous class-F power amplifier (PA) is investigated, designed, and fabricated. The new auxiliary parameter (beta + alpha cos(2)theta) , is proposed to increase the efficiency in comparison with the old auxiliary parameter (1 + delta cos theta). A novel methodology based on the smith chart design space and the proposed auxiliary parameter is introduced and analyzed. The design methodology, by controlling harmonic interferences, expands the amplifier bandwidth to below 1 GHz (up to 200 MHz). The laterally diffused metal-oxide-semiconductor (LDMOS) is selected, and an optimal bias point for its best performance is considered. Also, microstrip feedback based on the low-impedance coupled line is designed to accomplish transistor unconditional stability. Then, a ladder network based on the radial lines is designed as a harmonic control circuit, which controls harmonics up to 5th into the proposed design space. To verify this design approach, an extended continuous class-F power amplifier is designed and fabricated to operate at 0.2-1.7 GHz frequency range. Measurement results of the implemented PA shown that the output power of 38-40.2 dBm and the power gain of 13-15.2 dB were obtained. In addition, the final PA achieved a remarkable 53-79% drain efficiency over the whole operation bandwidth.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":91,"string":"91"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":255,"string":"255"}}},{"rowIdx":256,"cells":{"question_id":{"kind":"string","value":"Tim G neysu"},"question":{"kind":"string","value":"Generate an abstract for the title \"High-Performance Ideal Lattice-Based Cryptography on 8-Bit ATxmega Microcontrollers\" using the following items: lattice-based cryptography, implementation issues, constrained platforms, NTT, feasibility"},"answer":{"kind":"string","value":"Over the last years lattice-based cryptography has received much attention due to versatile average-case problems like Ring-LWE or Ring-SIS that appear to be intractable by quantum computers. But despite of promising constructions, only few results have been published on implementation issues on very constrained platforms. In this work we therefore study and compare implementations of Ring-LWE encryption and the Bimodal Lattice Signature Scheme BLISS on an 8-bit Atmel ATxmega128 microcontroller. Since the number theoretic transform NTT is one of the core components in implementations of lattice-based cryptosystems, we review the application of the NTT in previous implementations and present an improved approach that significantly lowers the runtime for polynomial multiplication. Our implementation of Ring-LWE encryption takes 27﾿ms for encryption and 6.7﾿ms for decryption. To compute a BLISS signature, our software takes 329﾿ms and 88﾿ms for verification. These results outperform implementations on similar platforms and underline the feasibility of lattice-based cryptography on constrained devices."},"correct_answer":{"kind":"string","value":"Over the last years lattice-based cryptography has received much attention due to versatile average-case problems like Ring-LWE or Ring-SIS that appear to be intractable by quantum computers. But despite of promising constructions, only few results have been published on implementation issues on very constrained platforms. In this work we therefore study and compare implementations of Ring-LWE encryption and the Bimodal Lattice Signature Scheme BLISS on an 8-bit Atmel ATxmega128 microcontroller. Since the number theoretic transform NTT is one of the core components in implementations of lattice-based cryptosystems, we review the application of the NTT in previous implementations and present an improved approach that significantly lowers the runtime for polynomial multiplication. Our implementation of Ring-LWE encryption takes 27﾿ms for encryption and 6.7﾿ms for decryption. To compute a BLISS signature, our software takes 329﾿ms and 88﾿ms for verification. These results outperform implementations on similar platforms and underline the feasibility of lattice-based cryptography on constrained devices."},"documents":{"kind":"list like","value":["Title: Cryptanalysis with COPACOBANA\nYear: 2008\n\nAbstract: Cryptanalysis of ciphers usually involves massive computations. The security parameters of cryptographic algorithms are commonly chosen so that attacks are infeasible with available computing resources. This contribution presents a variety of cryptanalytical applications utilizing the COPACOBANA (Cost-Optimized Parallel Code Breaker) machine which is a high-performance, low-cost cluster consisting of 120 Field Programmable Gate Arrays (FPGA). COPACOBANA appears to be the only such reconfigurable parallel FPGA machine optimized for code breaking tasks reported in the open literature. Depending on the actual algorithm, the parallel hardware architecture can outperform conventional computers by several orders of magnitude. In this work, we will focus on novel implementations of cryptanalytical algorithms, utilizing the impressive computational power of COPACOBANA. We describe various exhaustive key search attacks on symmetric ciphers and demonstrate an attack on a security mechanism employed in the electronic passport. Furthermore, we describe time-memory tradeoff techniques which can, e.g., be used for attacking the popular A5/1 algorithm used in GSM voice encryption. In addition, we introduce efficient implementations of more complex cryptanalysis on asymmetric cryptosystems, e.g., Elliptic Curve Cryptosystems (ECC) and number co-factorization for RSA.","Title: Kryptografie auf programmierbarer Hardware.\nYear: 2010\n\nAbstract: Zusammenfassung Sicherheitsmechanismen und kryptografische Verfahren werden mittlerweile in sehr vielen eingebetteten Systemen eingesetzt.\n Beim Entwurf solcher Systeme ist neben dem Schutz von Daten und der Nachrichtenauthentizität oft zu berücksichtigen, dass\n die implementierten Sicherheitsmechanismen keine Einschränkungen der Leistungsfähigkeit der Systeme zur Folge haben. Der Beitrag\n beleuchtet, wie derartige Anforderungen mit Hilfe von programmierbarer Hardware umgesetzt werden können.","Title: Enhanced Lattice-Based Signatures on Reconfigurable Hardware\nYear: 2014\n\nAbstract: The recent Bimodal Lattice Signature Scheme Bliss showed that lattice-based constructions have evolved to practical alternatives to RSA or ECC. Besides reasonably small signatures with 5600 bits for a 128-bit level of security, Bliss enables extremely fast signing and signature verification in software. However, due to the complex sampling of Gaussian noise with high precision, it is not clear whether this scheme can be mapped efficiently to embedded devices. Even though the authors of Bliss also proposed a new sampling algorithm using Bernoulli variables this approach is more complex than previous methods using large precomputed tables. The clear disadvantage of using large tables for high performance is that they cannot be used on constrained computing environments, such as FPGAs, with limited memory. In this work we thus present techniques for an efficient Cumulative Distribution Table CDT based Gaussian sampler on reconfigurable hardware involving Peikert's convolution lemma and the Kullback-Leibler divergence. Based on our enhanced sampler design, we provide a first Bliss architecture for Xilinx Spartan-6 FPGAs that integrates fast FFT/NTT-based polynomial multiplication, sparse multiplication, and a Keccak hash function. Additionally, we compare the CDT with the Bernoulli approach and show that for the particular Bliss-I parameter set the improved CDT approach is faster with lower area consumption. Our core uses 2,431 slices, 7.5 BRAMs, and 6 DSPs and performs a signing operation in 126 μs on average. Verification takes even less with 70 μs.","Title: Towards one cycle per bit asymmetric encryption: code-based cryptography on reconfigurable hardware\nYear: 2012\n\nAbstract: Most advanced security systems rely on public-key schemes based either on the factorization or the discrete logarithm problem. Since both problems are known to be closely related, a major breakthrough in cryptanalysis tackling one of those problems could render a large set of cryptosystems completely useless. Code-based public-key schemes are based on the alternative security assumption that decoding generic linear binary codes is NP-complete. In the past, most researchers focused on the McEliece cryptosystem, neglecting the fact that the scheme by Niederreiter has some important advantages. Smaller keys, more practical plain and ciphertext sizes and less computations. In this work we describe a novel FPGA implementation of the Niederreiter scheme, showing that its advantages can result a very efficient design for an asymmetric cryptosystem that can encrypt more than 1.5 million plaintexts per seconds on a Xilinx Virtex-6 FPGA, outperforming all other popular public key cryptosystems by far.","Title: Trojan Side-Channels: Lightweight Hardware Trojans through Side-Channel Engineering\nYear: 2009\n\nAbstract: The general trend in semiconductor industry to separate design from fabrication leads to potential threats from untrusted integrated circuit foundries. In particular, malicious hardware components can be covertly inserted at the foundry to implement hidden backdoors for unauthorized exposure of secret information. This paper proposes a new class of hardware Trojans which intentionally induce physical side-channels to convey secret information. We demonstrate power side-channels engineered to leak information below the effective noise power level of the device. Two concepts of very small implementations of Trojan side-channels (TSC) are introduced and evaluated with respect to their feasibility on Xilinx FPGAs. Their lightweight implementations indicate a high resistance to detection by conventional test and inspection methods. Furthermore, the proposed TSCs come with a physical encryption property, so that even a successful detection of the artificially introduced side-channel will not allow unhindered access to the secret information.","Title: DSPs, BRAMs, and a Pinch of Logic: Extended Recipes for AES on FPGAs\nYear: 2010\n\nAbstract: We present three lookup-table-based AES implementations that efficiently use the BlockRAM and DSP units embedded within Xilinx Virtex-5 FPGAs. An iterative module outputs a 32-bit AES round column every clock cycle, with a throughput of 1.67 Gbit/s when processing two 128-bit inputs. This construct is then replicated four times to provide a complete AES round per cycle with 6.7 Gbit/s throughput when processing eight input streams. This, in turn, is replicated ten times for a fully unrolled design providing over 52 Gbit/s of throughput. We also present implementations of a BRAM-based AES key-expansion, CMAC, and CTR modes of operation. Results for designs where DSPs are replaced by regular logic are also presented. The combination and arrangement of the specialized embedded functions available in the FPGA allows us to implement our designs using very few traditional user logic elements such as flip-flops and lookup tables, yet still achieve these high throughputs. HDL source code, simulation testbenches, and software tool commands to reproduce reported results for the three AES variants and CMAC mode are made publicly available. Our contribution concludes with a discussion on comparing cipher implementations in the literature, and why these comparisons can be meaningless without a common reporting methodology, or within the context of a constrained target application.","Title: PRINCE - A Low-Latency Block Cipher for Pervasive Computing Applications - Extended Abstract.\nYear: 2012\n\nAbstract: This paper presents a block cipher that is optimized with respect to latency when implemented in hardware. Such ciphers are desirable for many future pervasive applications with real-time security needs. Our cipher, named PRINCE, allows encryption of data within one clock cycle with a very competitive chip area compared to known solutions. The fully unrolled fashion in which such algorithms need to be implemented calls for innovative design choices. The number of rounds must be moderate and rounds must have short delays in hardware. At the same time, the traditional need that a cipher has to be iterative with very similar round functions disappears, an observation that increases the design space for the algorithm. An important further requirement is that realizing decryption and encryption results in minimum additional costs. PRINCE is designed in such a way that the overhead for decryption on top of encryption is negligible. More precisely for our cipher it holds that decryption for one key corresponds to encryption with a related key. This property we refer to as alpha-reflection is of independent interest and we prove its soundness against generic attacks.","Title: Efficient Hash Collision Search Strategies on Special-Purpose Hardware\nYear: 2007\n\nAbstract: Hash functions play an important role in various cryptographic applications. Modern cryptography relies on a few but supposedly well analyzed hash functions which are mostly members of the so-called MD4-family. This work shows whether it is possible to significantly speedup collision search for MD4-family hash functions using special-purpose hardware. A thorough analysis of the computational requirements for MD4-family hash functions and corresponding collision attacks reveals that a microprocessor based architecture is best suited for the implementation of collision search algorithms. Consequently, we designed and implemented a (concerning MD4-family hash-functions) general-purpose microprocessor with minimal area requirements and, based on this, a full collision search unit. Comparing the performance characteristics of both ASICs with standard PC processors and clusters, it turns out that our design, massively parallelized, is nearly four times more cost-efficient than parallelized standard PCs. Although with further optimizations this factor can certainly be improved, we believe that special-purpose hardware does not provide a too significant benefit for hash collision search algorithms with respect to modern off-the-shelf general-purpose processors.","Title: Ultra High Performance ECC over NIST Primes on Commercial FPGAs\nYear: 2008\n\nAbstract: Elliptic Curve Cryptosystems (ECC) have gained increasing acceptance in practice due to their significantly smaller bit size of the operands compared to other public-key cryptosystems. Since their computational complexity is often lower than in the case of RSA or discrete logarithm schemes, ECC are often chosen for high performance public-key applications. However, despite a wealth of research regarding high-speed software and high-speed FPGA implementation of ECC since the mid 1990s, providing truly high-performance ECC on readily available (i.e., non-ASIC) platforms remains an open challenge. This holds especially for ECC over prime fields, which are often preferred over binary fields due to standards in Europe and the US.This work presents a new architecture for an FPGA-based ultra high performance ECC implementation over prime fields. Our architecture makes intensive use of the DSP blocks in modern FPGAs, which are embedded arithmetic units actually intended to accelerate digital signal processing algorithms. We describe a novel architecture and algorithms for performing ECC arithmetic and describe the actual implementation of standard compliant ECC based on the NIST primes P-224 and P-256. We show that ECC on Xilinx's Virtex-4 SX55 FPGA can be performed at a rate of more than 37,000 point multiplications per second. Our architecture outperforms all single-chip hardware implementations over prime fields in the open literature by a wide margin.","Title: Full lattice basis reduction on graphics cards\nYear: 2011\n\nAbstract: Recent lattice enumeration GPU implementations are very useful to find shortest vectors within a given lattice but are also highly dependent on a lattice basis reduction that still runs on a CPU. Therefore we present an implementation of a full lattice basis reduction that makes exclusive use of GPUs to close this gap. Hence, we show that GPUs are, as well, suited to apply lattice basis reduction algorithms that were merely of theoretical interest so far due to their enormous computational effort. We modified and optimized these algorithms to fit the architecture of graphics cards, in particular we focused on Givens Rotations and the All-swap reduction method. Eventually, our GPU implementation achieved a significant speed-up for given lattice challenges compared to the NTL implementation running on an CPU of about 18, providing at least the same reduction quality.","Title: Smaller keys for code-based cryptography: QC-MDPC mceliece implementations on embedded devices\nYear: 2013\n\nAbstract: In the last years code-based cryptosystems were established as promising alternatives for asymmetric cryptography since they base their security on well-known NP-hard problems and still show decent performance on a wide range of computing platforms. The main drawback of code-based schemes, including the popular proposals by McEliece and Niederreiter, are the large keys whose size is inherently determined by the underlying code. In a very recent approach, Misoczki et al. proposed to use quasi-cyclic MDPC (QC-MDPC) codes that allow for a very compact key representation. In this work, we investigate novel implementations of the McEliece scheme using such QC-MDPC codes tailored for embedded devices, namely a Xilinx Virtex-6 FPGA and an 8-bit AVR microcontroller. In particular, we evaluate and improve different approaches to decode QC-MDPC codes. Besides competitive performance for encryption and decryption on the FPGA, we achieved a very compact implementation on the microcontroller using only 4,800 and 9,600 bits for the public and secret key at 80 bits of equivalent symmetric security.","Title: Parallel Computing with Low-Cost FPGAs: A Framework for COPACOBANA\nYear: 2007\n\nAbstract: In many disciplines such as applied sciences or computer science, computationally challenging problems demand for extraordinary computing power, mostly provided by super computers or clusters of conventional desktop CPUs. During the last decides, several flavours of super computers have evolved. most of which are suitable for a specific type of problem. In general. dedicated clusters and super computers suffer from their extremely high cost per computation and are, due to the lack of cheap alternatives, currently the only possible solution to computational hard problems. More recently. emerging low-cost FPGAs tend to be a very cost-effective alternative to conventional CPUs for solving at least sonic of the computational hard problems such as those appearing in cryptanalysis and bio-informatics. In cryptanalysis, breaking symmetric or asymmetric ciphers is computationally extremely demanding. Since the security parameters (in particular the key length) of almost all practical crypto algorithms are chosen such that attacks with conventional computers are computationally infeasible. the only promising way to tackle existing ciphers (assuming no mathematical breakthrough) is to build Special-purpose hardware. Dedicating those machines to the task of cryptanalysis holds the promise of a dramatically improved cost-performance ratio so that breaking of commercial ciphers comes within reach. This contribution presents the realization of a very genetic framework for the COPACOBANA (Cost-Optimized Parallel Code Breaker) machine(1). COPACOBANA consists of up to 120 low-cost FPGAs and call be realized for US$ 10,000 while being able to outperform conventional computers by several orders in magnitude, depending oil the application. The presented framework allows for a simple distribution of parallelizable tasks and corresponding control mechanisms. With the framework at hand. the overhead and. as a consequence, the time to deploy custom made applications on the COPACOBANA platform is minimized. Exemplarily. we show how cryptanalytical applications can be based on top of the framework. resulting ill a very low cost per computation.","Title: Towards Practical Lattice-Based Public-Key Encryption on Reconfigurable Hardware.\nYear: 2013\n\nAbstract: With this work we provide further evidence that lattice-based cryptography is a promising and efficient alternative to secure embedded applications. So far it is known for solid security reductions but implementations of specific instances have often been reported to be too complex beyond any practicability. In this work, we present an efficient and scalable micro-code engine for Ring-LWE encryption that combines polynomial multiplication based on the Number Theoretic Transform (NTT), polynomial addition, subtraction, and Gaussian sampling in a single unit. This unit can encrypt and decrypt a block in 26.19 mu s and 16.80 mu s on a Virtex-6 LX75T FPGA, respectively - at moderate resource requirements of about 1506 slices and a few block RAMs. Additionally, we provide solutions for several practical issues with Ring-LWE encryption, including the reduction of ciphertext expansion, error rate and constant-time operation. We hope that this contribution helps to pave the way for the deployment of ideal lattice-based encryption in future real-world systems.","Title: Lightweight code-based cryptography: QC-MDPC McEliece encryption on reconfigurable devices\nYear: 2014\n\nAbstract: With the break of RSA and ECC cryptosystems in an era of quantum computing, asymmetric code-based cryptography is an established alternative that can be a potential replacement. A major drawback are large keys in the range between 50kByte to several MByte that prevented real-world applications of code-based cryptosystems so far. A recent proposal by Misoczki et al. showed that quasi-cyclic moderate density parity-check (QC-MDPC) codes can be used in McEliece encryption -- reducing the public key to just 0.6 kByte to achieve a 80-bit security level. Despite of reasonably small key sizes that could also enable small designs, previous work only report high-performance implementations with high resource consumptions of more than 13,000 slices on a large Xilinx Virtex-6 FPGA for a combined en-/decryption unit. In this work we focus on lightweight implementations of code-based cryptography and demonstrate that McEliece encryption using QC-MDPC codes can be implemented with a significantly smaller resource footprint -- still achieving reasonable performance sufficient for many applications, e.g., challenge-response protocols or hybrid firmware encryption. More precisely, our design requires just 68 slices for the encryption and around 150 slices for the decryption unit and is able to en-/decrypt an input block in 2.2ms and 13.4 ms, respectively.","Title: Transforming write collisions in block RAMs into security applications\nYear: 2009\n\nAbstract: Due to their versatile and generic structure, field programmable gate arrays (FPGA) allow dynamic reconfiguration of their logical resources just by loading configuration files. However, this flexibility also opens up the threat of theft of intellectual property (IP) since these configuration files can be easily extracted and cloned. In this context, the ability to bind a configuration to a specific device is an important step to prevent product counterfeiting. In this paper, we present a novel strategy to identify and authenticate FPGAs in applications using intrinsic, device-specific information (also known as physically unclonable functions). Our solution is based on the output of intentionally induced write collisions in synchronous dual-port block RAM (BRAM). We show that the output of such write collisions can be used to create unique device signatures. In addition to applications for chip identification and authentication, we also propose a solution to efficiently create secret keys on-chip. As a last contribution, we outline how to transform our idea into a circuit for true random number generation (TRNG).","Title: Compact implementation and performance evaluation of hash functions in ATtiny devices\nYear: 2012\n\nAbstract: The pervasive diffusion of electronic devices in security and privacy sensitive applications has boosted research in cryptography. In this context, the study of lightweight algorithms has been a very active direction over the last years. In general, symmetric cryptographic primitives are good candidates for low-cost implementations. For example, several previous works have investigated the performance of block ciphers on various platforms. Motivated by the recent SHA3 competition, this paper extends these studies to another family of cryptographic primitives, namely hash functions. We implemented different algorithms on an ATMEL AVR ATtiny45 8-bit microcontroller, and provide their performance evaluation. All the implementations were carried out with the goal of minimizing the code size and memory utilization, and are evaluated using a common interface. As part of our contribution, we make all the corresponding source codes available on a web page, under an open-source license. We hope that this paper provides a good basis for researchers and embedded system designers who need to include more and more functionalities in next generation smart devices.","Title: Code-based cryptography on reconfigurable hardware: tweaking Niederreiter encryption for performance.\nYear: 2013\n\nAbstract: Today’s public-key schemes that are either based on the factorization or the discrete logarithm problem. Since both problems are closely related, a major breakthrough in cryptanalysis (e.g., with the advent of quantum computing will render nearly all currently employed security system useless. Code-based public-key schemes rely on the alternative security assumption that decoding generic linear binary codes is NP-complete. Two code-based schemes for public-key encryption are available due to McEliece and Niederreiter. Although most researchers analyzed and implemented McEliece’s cryptosystem, we show in this work that the scheme by Niederreiter has some important advantages, such as smaller keys, more practical plain and ciphertext sizes and less computation complexity. In particular, we propose an efficient FPGA implementation of Niederreiter’s scheme that can encrypt more than 1.5 million plaintexts per seconds on a Xilinx Virtex-6 FPGA—outperforming all known implementations of other popular public-key cryptosystems so far.","Title: An experimentally verified attack on full grain-128 using dedicated reconfigurable hardware\nYear: 2011\n\nAbstract: In this paper we describe the first single-key attack which can recover the full key of the full version of Grain-128 for arbitrary keys by an algorithm which is significantly faster than exhaustive search (by a factor of about 238). It is based on a new version of a cube tester, which uses an improved choice of dynamic variables to eliminate the previously made assumption that ten particular key bits are zero. In addition, the new attack is much faster than the previous weak-key attack, and has a simpler key recovery process. Since it is extremely difficult to mathematically analyze the expected behavior of such attacks, we implemented it on RIVYERA, which is a new massively parallel reconfigurable hardware, and tested its main components for dozens of random keys. These tests experimentally verified the correctness and expected complexity of the attack, by finding a very significant bias in our new cube tester for about 7.5% of the keys we tested. This is the first time that the main components of a complex analytical attack are successfully realized against a full-size cipher with a special-purpose machine. Moreover, it is also the first attack that truly exploits the configurable nature of an FPGA-based cryptanalytical hardware.","Title: Using Data Contention in Dual-ported Memories for Security Applications\nYear: 2012\n\nAbstract: Field Programmable Gate Arrays (FPGA) provide the invaluable feature of dynamic hardware reconfiguration by loading configuration bit files. However, this flexibility also opens up the threat of theft of Intellectual Property (IP) since these configuration files can be easily extracted and cloned. In this context, the ability to bind an application configuration to a specific device is an important step to prevent product counterfeiting. Furthermore, such a technology can also enable advanced business models such as device-specific feature activation. In this work, we present a new technique to generate entropy on FPGA device--based on data contention in the hardware circuitry. For this entropy, we use the output of intentionally generated write collisions in synchronous dual-ported block RAMs (BRAM). We show that the parts of this output generated by such write collisions can be either probabilistic but also deterministic and device-specific. The characteristics of such an entropy source can be used for a large variety of security applications, such as chip identification and device authentication. In addition to that, we also propose a solution to efficiently create cryptographic keys on-chip at runtime. As a last contribution, we eventually present a strategy how to transform this entropy source into a circuit for True Random Number Generation (TRNG).","Title: Reconfigurable trusted computing in hardware\nYear: 2007\n\nAbstract: Trusted Computing (TC) is an emerging technology towards building trustworthy computing platforms. The TrustedComputing Group (TCG) has proposed several specifications to implement TC functionalities by extensions to common computing platforms, particularly the underlying hardware with a Trusted Platform Module (TPM). However, actual TPMs are mostly available for workstations and servers nowadays and rather for specific domainapplications and not primarily for embedded systems. Further, the TPM specifications are becoming monolithic andmore complex while the applications demand a scalable and flexible usage of TPM functionalities. In this paper we propose a reconfigurable (hardware) architecture with TC functionalities where we focus on TPMsas proposed by the TCG specifically designed for embedded platforms. Our approach allows for (i) an efficient andscalable design and update of TPM functionalities, in particular for hardware-based crypto engines and accelerators, (ii) establishing a minimal trusted computing base in hardware, (iii) including the TPM as well as its functionalities into the chain of trust that enables to bind sensitive data to the underlying reconfigurable hardware, and (iv) designing a manufacturer independent TPM. We discuss possible implementations based on current FPGAs and point out the associated challenges, in particular with respect to protection of the internal TPM state since it must not be subject to manipulation, replay, and cloning","Title: Attacking atmel's cryptomemory EEPROM with special-purpose hardware\nYear: 2013\n\nAbstract: Atmel's CryptoMemory devices are non-volatile memories with cryptographically secured access control. Recently, the authentication mechanism of these devices have been shown to be severely vulnerable. More precisely, to recover the secret key the published attack requires only two to six days of computation on a cluster involving 200 CPU cores. In this work, we identified and applied theoretical improvements to this attack and mapped it to a reconfigurable computing cluster, known as RIVYERA. Our solution provides significantly higher performance exceeding the previous implementation by a factor of 7.27, revealing the secret key obtained from the internal state in 0.55 days on average using only 30 authentication frames.","Title: MicroEliece: McEliece for Embedded Devices\nYear: 2009\n\nAbstract: Most advanced security systems rely on public-key schemes based either on the factorization or the discrete logarithm problem. Since both problems are known to be closely related, a major breakthrough in cryptanalysis tackling one of those problems could render a large set of cryptosystems completely useless. The McEliece public-key scheme is based on the alternative security assumption that decoding unknown linear binary codes is NP-complete. In this work, we investigate the efficient implementation of the McEliece scheme on embedded systems what was --- up to date --- considered a challenge due to the required storage of its large keys. To the best of our knowledge, this is the first time that the McEliece encryption scheme is implemented on a low-cost 8-bit AVR microprocessor and a Xilinx Spartan-3AN FPGA.","Title: DSPs, BRAMs and a Pinch of Logic: New Recipes for AES on FPGAs\nYear: 2008\n\nAbstract: We present an AES cipher implementation that is based on the BlockRAM and DSP units embedded within Xilinx's Virtex-5 FPGAs. An iterative \"basic\" module outputs a 32 bit column of an AES round each clock cycle, with a throughput of 1.76 Gbit/s when processing two 128 bit inputs. This construct is replicated four times for a 128 bit datapath for a full AES round with 6.21 Gbit/s throughput when processing eight inputs. Finally, the \"round\" module is replicated ten times for a fully unrolled design that yields over 55 Gbit/s of throughput. The combination and arrangement of the specialized embedded functions available in the FPGA allows us to implement our designs using very few traditional user logic elements such as flip-flops and lookup tables, yet still achieve these high throughputs. The complete source code for these designs is made publicly available for use in further research and for replicating our results. Our contribution ends with a discussion of comparing cipher implementations in the literature, and why these comparisons can be meaningless without a common reporting style, platform, or within the context of a specific constrained application.","Title: Breaking Legacy Banking Standards with Special-Purpose Hardware\nYear: 2008\n\nAbstract: In the field of eCommerce, online-banking is one of the major application requiring the usage of modern cryptography to protect the confidentiality and integrity of financial transactions between users and the banking system. In banking applications of some countries, the authorization of user transactions is performed with support of cryptographic One-Time-Password (OTP) tokens implementing ANSI X9.9-based challenge-response protocols.The legacy ANSI X9.9 standard is a DES-based authentication method on which we will demonstrate an attack based on a special-purpose hardware cluster. In this work we show how to break such an OTP-token with little effort in terms of costs and time. With an investment of about US $ 10,000 we are able to perform an attack which computes the key of a DES-based OTP token in less than a week having only three challenge-response pairs. Our attack can even be scaled linearly according to the budget of the attacker resulting in even faster breaking times. With this work, we want to point out once more that the immediate migration from legacy products using the DES algorithm is absolutely mandatory for security critical applications.","Title: True random number generation in block memories of reconfigurable devices\nYear: 2010\n\nAbstract: We present concepts and implementations to transform write collisions in memory blocks into an entropy source for random number generation. Write collisions in dual-ported block memories occur when both memory ports write simultaneously different data at the same memory location. After a thorough analysis of this effect, we present a robust methodology to generate digitized noise and randomness from such write collisions and also provide details how to implement post-processing methods for efficient bias and correlation removal. Finally, we present three concepts and implementations for random number generators stages that can deliver random data at an output rate of more than 100 MBit/s.","Title: Side channels as building blocks.\nYear: 2012\n\nAbstract: Since the introduction of the first side-channel analyses in academia about 15 years ago, several physical attacks have been presented that exploit side-channel leakages to break implementations of cryptographic algorithms. This article deals with the same physical property of electronic devices, but focuses on the art of tailoring it for constructive uses. More precisely, two scenarios, i.e., hardware Trojans and IP watermarking, are illustrated in which the designer of an electronic circuit can add functionality by considering side channels as part of the available design space. Both applications use the same concept, i.e., deliberately leaking a secret through a side channel while keeping the introduced side channel hidden from adversaries and attackers. This article provides a broad overview of the existing works for both applications and should serve as a comprehensible introduction to the underlying field of research. This includes many subtle details that have not been discussed in literature yet, including existing shortcomings and possible improvements to the existing works. The solutions summarized in this article provide general guidelines for theorists and practitioners to use side channels constructively to achieve designs that are robust against detection and removal. Furthermore, we present an entirely new design of a Trojan side-channel. This architecture demonstrates the potential of a Trojan side-channel that is neatly tailored to the targeted implementation. The new design removes all non-invasive starting points a third party could use to analyze or get access to the secret-channel.","Title: Securely sealing Multi-FPGA systems\nYear: 2012\n\nAbstract: The importance of hardware security of electronic systems is rapidly increasing due to (1) the increasing reliance of mass-produced and mission-critical systems on embedded electronics, and (2) the ever-growing supply chains that disentangle chip designers and manufacturers from OEMs. Our work shows how to dramatically reduce vulnerability to Trojan-horse injection and in-field component replacement. We propose methods to verify the authenticity and integrity of an FPGA configuration during startup and at runtime. We also developed efficient protocols for electronic sealing of a multi-FPGA system, which automatically enforces the system configuration detected upon power-up and bans further modifications.","Title: The future of high-speed cryptography: new computing platforms and new ciphers\nYear: 2011\n\nAbstract: Almost all of today's security systems rely on cryptographic primitives as core components which are usually considered the most trusted part of the system. The realization of these primitives on the underlying processing platform plays a crucial role for any real-world deployment. In this work, we discuss new trends in public-key cryptography that could potentially establish as alternatives to the currently used RSA and ECC cryptosystems. Analyzing these trends from a developer's perspective, we identify the requirements for optimal processing architectures. Moreover, we investigate if these requirements are already satisfied with latest processing platforms, i.e., which of the streaming, hybrid, multi-core or application-specific instructions processors provide a most promising target architecture.","Title: New Protection Mechanisms for Intellectual Property in Reconfigurable Logic\nYear: 2007\n\nAbstract: The distinct advantage of SRAM-based Field Programmable Gate Arrays (FPGA) is their flexibility for configuration changes. But this opens up the threat of Intellectual Property (IP) theft since the system configuration is stored in easy-to-access Flash memory. High-end FPGAs have already been extended with symmetric-key decryption engines used to load an encrypted version of the configuration that cannot simply be copied and used without knowledge of the secret key. However, with respect to business and licensing processes, this protection system lacks a convenient scheme for key transport and installation. We propose a new protection scheme for the IP of circuits in configuration bit files that provides a significant improvement to the current unsatisfying situation. It uses both public-key and symmetric cryptography, but does not burden FPGAs with the usual overhead of public-key cryptography: While it needs hard-wired symmetric cryptography, the public-key functionality is moved into a temporary configuration bit stream for a one-time setup procedure. This approach requires only very few modifications to current FPGA technology. Using five basic stages, the new protection scheme allows new accounting models for volume licensing of IP, with automated key installation on FPGAs taking place at the customer's site.","Title: IPSecco: A lightweight and reconfigurable IPSec core\nYear: 2012\n\nAbstract: In this paper we propose a reconfigurable lightweight Internet Protocol Security (IPSec) hardware core. Our architecture supports the main IPSec protocols; namely Authentication Header (AH), Encapsulating Security Payload (ESP), and Internet Key Exchange (IKE). In this work, the cryptographic algorithms and their modes of operation, which are at the heart of the IPSec protocols, are implemented in hardware. Instead of re-implementing common IPSec configurations, which are deemed “too heavy” for pervasive devices, we evaluate efficient implementations of standardized and/or well-known lightweight and hardware-friendly algorithms. In particular, we examine different versions of Present, Grøstl, Photon, and a very compact ECC core. As a consequence, we present IPSecco, a core with adequate security and only moderate resource requirements, making it suitable for lightweight devices. We selected the Xilinx Spartan family of Field Programmable Gate Arrays (FPGA) as target platform due its low-power footprint and reduced costs compared to other FPGAs. Our results show that it is possible to realize a high performance IPSec core even on members of the Spartan-3 family.","Title: Towards efficient arithmetic for lattice-based cryptography on reconfigurable hardware\nYear: 2012\n\nAbstract: In recent years lattice-based cryptography has emerged as quantum secure and theoretically elegant alternative to classical cryptographic schemes (like ECC or RSA). In addition to that, lattices are a versatile tool and play an important role in the development of efficient fully or somewhat homomorphic encryption (SHE/FHE) schemes. In practice, ideal lattices defined in the polynomial ring ℤp[x]/〈xn+1〉 allow the reduction of the generally very large key sizes of lattice constructions. Another advantage of ideal lattices is that polynomial multiplication is a basic operation that has, in theory, only quasi-linear time complexity of ${\\mathcal O}(n \\log{n})$ in ℤp[x]/〈xn+1〉. However, few is known about the practical performance of the FFT in this specific application domain and whether it is really an alternative. In this work we make a first step towards efficient FFT-based arithmetic for lattice-based cryptography and show that the FFT can be implemented efficiently on reconfigurable hardware. We give instantiations of recently proposed parameter sets for homomorphic and public-key encryption. In a generic setting we are able to multiply polynomials with up to 4096 coefficients and a 17-bit prime in less than 0.5 milliseconds. For a parameter set of a SHE scheme (n=1024,p=1061093377) our implementation performs 9063 polynomial multiplications per second on a mid-range Spartan-6.","Title: Exploiting the Power of GPUs for Asymmetric Cryptography\nYear: 2008\n\nAbstract: Modern Graphics Processing Units (GPU) have reached a dimension with respect to performance and gate count exceeding conventional Central Processing Units (CPU) by far. Many modern computer systems include --- beside a CPU --- such a powerful GPU which runs idle most of the time and might be used as cheap and instantly available co-processor for general purpose applications.In this contribution, we focus on the efficient realisation of the computationally expensive operations in asymmetric cryptosystems on such off-the-shelf GPUs. More precisely, we present improved and novel implementations employing GPUs as accelerator for RSA and DSA cryptosystems as well as for Elliptic Curve Cryptography (ECC). Using a recent Nvidia 8800GTS graphics card, we are able to compute 813 modular exponentiations per second for RSA or DSA-based systems with 1024 bit integers. Moreover, our design for ECC over the prime field P-224 even achieves the throughput of 1412 point multiplications per second.","Title: Special-Purpose Hardware for Solving the Elliptic Curve Discrete Logarithm Problem\nYear: 2008\n\nAbstract: The resistance against powerful index-calculus attacks makes Elliptic Curve Cryptosystems (ECC) an interesting alternative to conventional asymmetric cryptosystems, like RSA. Operands in ECC require significantly less bits at the same level of security, resulting in a higher computational efficiency compared to RSA. With growing computational capabilities and continuous technological improvements over the years, however, the question of the security of ECC against attacks based on special-purpose hardware arises. In this context, recently emerged low-cost FPGAs demand for attention in the domain of hardware-based cryptanalysis: the extraordinary efficiency of modern programmable hardware devices allow for a low-budget implementation of hardware-based ECC attacks---without the requirement of the expensive development of ASICs. With focus on the aspect of cost-efficiency, this contribution presents and analyzes an FPGA-based architecture of an attack against ECC over prime fields. A multi-processing hardware architecture for Pollard's Rho method is described. We provide results on actually used key lengths of ECC (128 bits and above) and estimate the expected runtime for a successful attack. As a first result, currently used elliptic curve cryptosystems with a security of 160 bit and above turn out to be infeasible to break with available computational and financial resources. However, some of the security standards proposed by the Standards for Efficient Cryptography Group (SECG) become subject to attacks based on low-cost FPGAs.","Title: Generic side-channel countermeasures for reconfigurable devices\nYear: 2011\n\nAbstract: In this work, we propose and evaluate generic hardware countermeasures against DPA attacks for recent FPGA devices. The proposed set of FPGA-specific countermeasures can be combined to resist a large variety of first-order DPA attacks, even with 100 million recorded power traces. This set includes generic and resource-efficient countermeasures for on-chip noise generation, random-data processing delays and S-box scrambling using dual-ported block memories. In particular, it is possible to build many of these countermeasures into a single IP-core or hard macro that then provides basic protection for any cryptographic implementation just by its inclusion in the design process - what is particularly useful for engineers with no or little background on security and side-channel attacks.","Title: Two Ip Protection Schemes For Multi-Fpga Systems\nYear: 2012\n\nAbstract: This paper proposes two novel protection schemes for multi-FPGA systems providing high security of IP designs licensed by IP vendors to system integrators and installed remotely in a hostile environment. In the first scheme, these useful properties are achieved by storing two different configuration keys inside an FPGA, while in the second scheme, they are obtained using a hardware white-box cipher for creating a trusted environment. Thanks to the proposed principles, FPGA configurations coming from different IP owners cannot be cloned or reverse-engineered by any involved party, including system integrator and other IP owners. The proposed schemes can be directly implemented in recent FPGAs such as Xilinx Spartan 6 and Virtex 6.","Title: Software Speed Records For Lattice-Based Signatures\nYear: 2013\n\nAbstract: Novel public-key cryptosystems beyond RSA and ECC are urgently required to ensure long-term security in the era of quantum computing. The most critical issue on the construction of such cryptosystems is to achieve security and practicability at the same time. Recently, lattice-based constructions were proposed that combine both properties, such as the lattice-based digital signature scheme presented at CHES 2012. In this work, we present a first highly-optimized SIMD-based software implementation of that signature scheme targeting Intel's Sandy Bridge and Ivy Bridge microarchitectures. This software computes a signature in only 634988 cycles on average on an Intel Core i5-3210M (Ivy Bridge) processor. Signature verification takes only 45036 cycles. This performance is achieved with full protection against timing attacks.","Title: Establishing Chain of Trust in Reconfigurable Hardware\nYear: 2007\n\nAbstract: Facing ubiquitous threats like computer viruses, trojans and theft of intellectual property, Trusted Computing (TC) is an emerging technology towards building trustworthy computing platforms. A recent initiative by the Trusted Computing Group (TCG) specifies the use of Trusted Platform Modules (TPM), currently implemented as dedicated, cost-effective crypto-chips mounted on the main board of computer systems. In this paper we propose implementations for TC functionalities based on more flexible and versatile approaches for reconfigurable and embedded architectures. Our approach allows for (i) a scalable design and update of TPM functionalities in embedded systems, (ii) the integration of the TPM hardware in the chain of trust to bind applications to the underlying TPM and the reconfigurable hardware, and (iii) the design of vendor independent TPMs.","Title: Achieving side-channel protection with dynamic logic reconfiguration on modern FPGAs\nYear: 2015\n\nAbstract: Reconfigurability is a unique feature of modern FPGA devices to load hardware circuits just on demand. This also implies that a completely different set of circuits might operate at the exact same location of the FPGA at different time slots, making it difficult for an external observer or attacker to predict what will happen at what time. In this work we present and evaluate a novel hardware implementation of the lightweight cipher PRESENT with built-in side-channel countermeasures based on dynamic logic reconfiguration. In our design we make use of Configurable Look-Up Tables (CFGLUT) integrated in modern Xilinx FPGAs to nearly instantaneously change hardware internals of our cipher implementation for improved resistance against side-channel attacks. We provide evidence from practical experiments based on a Spartan-6 platform that even with 10 million recorded power traces we were unable to detect a first-order leakage using the state-of-the-art leakage assessment.","Title: Evaluating the Duplication of Dual-Rail Precharge Logics on FPGAs.\nYear: 2015\n\nAbstract: Power-equalization schemes for digital circuits aim to harden cryptographic designs against power analysis attacks. With respect to dual-rail logics most of these schemes have originally been designed for ASIC platforms, but much efforts have been spent to map them to FPGAs as well. A particular challenge is here to apply those schemes to the predefined logic structures of FPGAs i.e., slices, LUTs, FFs, and routing switch boxes for which special tools are required. Due to the absence of such routing tools Yu and Schaumont presented the idea of duplicating i.e., dualizing a fully-placed-and-routed dual-rail precharge circuit with equivalent routing structures on an FPGA. They adopted such architecture from WDDL providing the Double WDDL DWDDL scheme. In this work we show that this general technique --- regardless of the underlying dual-rail logic --- is incapable to properly prevent side-channel leakages. Besides theoretical investigations on this issue we present practical evaluations on a Spartan-6 FPGA to demonstrate the flaws in such an approach. In detail, we consider an AES-128 encryption module realized by three dual-rail precharge logic styles as a case study and show that none of those schemes can provide the desired level of protection.","Title: GliFreD: Glitch-Free Duplication - Towards Power-Equalized Circuits on FPGAs.\nYear: 2018\n\nAbstract: Designers of secure hardware are required to harden their implementations against physical threats, such as power analysis attacks. In particular, cryptographic hardware circuits need to decorrelate their current consumption from the information inferred by processing (secret) data. A common technique to achieve this goal is the use of special logic styles that aim at equalizing the current consum...","Title: High-Speed Signatures From Standard Lattices\nYear: 2014\n\nAbstract: At CT-RSA 2014 Bai and Galbraith proposed a lattice-based signature scheme optimized for short signatures and with a security reduction to hard standard lattice problems. In this work we first refine the security analysis of the original work and propose a new 128-bit secure parameter set chosen for software efficiency. Moreover, we increase the acceptance probability of the signing algorithm through an improved rejection condition on the secret keys. Our software implementation targeting Intel CPUs with AVX/AVX2 and ARM CPUs with NEON vector instructions shows that even though we do not rely on ideal lattices, we are able to achieve high performance. For this we optimize the matrix-vector operations and several other aspects of the scheme and finally compare our work with the state of the art.","Title: Towards Side-Channel Resistant Implementations Of Qc-Mdpc Mceliece Encryption On Constrained Devices\nYear: 2014\n\nAbstract: Recent advances in code-based cryptography paved new ways for efficient asymmetric cryptosystems that combine decent performance with moderate key sizes. In this context, Misoczki et al. recently proposed the use of quasi-cyclic MDPC (QC-MDPC) codes for the McEliece cryptosystem. It was shown that these codes can provide both compact key representations and solid performance on high-end computing platforms. However, for widely used low-end microcontrollers only slow implementations for this promising construction have been presented so far.In this work we present an implementation of QC-MDPC McEliece encryption providing 80 bits of equivalent symmetric security on low-cost ARM Cortex-M4-based microcontrollers with a reasonable performance of 42 ms for encryption and 251-558 ms for decryption. Besides practical issues such as random error generation, we demonstrate side-channel attacks on a straightforward implementation of this scheme and finally propose timing-and instruction-invariant coding strategies and countermeasures to strengthen it against timing attacks as well as simple power analysis.","Title: Enabling SRAM-PUFs on Xilinx FPGAs\nYear: 2014\n\nAbstract: Physically Unclonable Functions (PUFs) based on the evaluation of uninitialized SRAM are one of the most promising PUF candidates to date. However, transferring their concept to Xilinx FPGAs is not straightforward since all SRAM-based block memories in these FPGAs are automatically cleared on power-up, destroying the desired initial bits of information. In this work we therefore propose a novel strategy to convert block memories of 28nm Xilinx FPGAs into SRAM-PUFs by exploiting their recently introduced feature of power-gating and partial reconfiguration.","Title: THOR - The hardware onion router\nYear: 2014\n\nAbstract: Security and privacy of data traversing internet have always been a major concern for all users. In this context, The Onion Routing (Tor) is the most successful protocol to anonymize global Internet traffic and is widely deployed as software on many personal computers or servers. In this paper, we explore the potential of modern reconfigurable devices to efficiently realize the Tor protocol on embedded devices. In particular, this targets the acceleration of the complex cryptographic operations involved in the handshake of routing nodes and the data stream encryption. Our hardware-based implementation on the Xilinx Zynq platform outperforms previous embedded solutions by more than a factor of 9 with respect to the cryptographic handshake - ultimately enabling quite inexpensive but highly efficient routers. Hence, we consider our work as a further milestone towards the development and the dissemination of low-cost and high performance onion relays that hopefully ultimately leads again to a more private Internet.","Title: Area optimization of lightweight lattice-based encryption on reconfigurable hardware\nYear: 2014\n\nAbstract: Ideal lattice-based cryptography gained significant attraction in the last years due to its versatility, simplicity and performance in implementations. Nevertheless, existing implementations of encryption schemes reported only results trimmed for high-performance what is certainly not sufficient for all applications in practice. To the contrary, in this work we investigate lightweight aspects and suitable parameter sets for Ring-LWE encryption and show optimizations that enable implementations even with very few resources on a reconfigurable hardware device. Despite of this restriction, we still achieve reasonable throughput that is sufficient for many today's and future applications.","Title: Lattice-Based Signatures: Optimization and Implementation on Reconfigurable Hardware\nYear: 2015\n\nAbstract: Nearly all of the currently used signature schemes, such as RSA or DSA, are based either on the factoring assumption or the presumed intractability of the discrete logarithm problem. As a consequence, the appearance of quantum computers or algorithmic advances on these problems may lead to the unpleasant situation that a large number of today’s schemes will most likely need to be replaced with more secure alternatives. In this work we present such an alternative—an efficient signature scheme whose security is derived from the hardness of lattice problems. It is based on recent theoretical advances in lattice-based cryptography and is highly optimized for practicability and use in embedded systems. The public and secret keys are roughly kB and kB long, while the signature size is approximately kB for a security level of around bits. We provide implementation results on reconfigurable hardware (Spartan/Virtex-6) and demonstrate that the scheme is scalable, has low area consumption, and even outperforms classical schemes.","Title: Fault Sensitivity Analysis Meets Zero-Value Attack\nYear: 2014\n\nAbstract: Previous works have shown that the combinatorial path delay of a cryptographic function, e.g., The AES S-box, depends on its input value. Since the relation between critical path delay and input value seems to be relatively random and highly dependent on the routing of the circuit, up to now only template or some collision attacks could reliably extract the used secret key of implementations not protected against fault attacks. Here we present a new attack which is based on the fact that, because of the zero-to-zero mapping of the AES Sbox inversion circuit, the critical path when processing the zero input is notably shorter than for all other inputs. Applying the attack to an AES design protected by an state-of-the-art fault detection scheme, we are able to fully recover the secret key in less than eight hours. Note that we neither require a known key measurement step (template case) nor a high similarity between different S-box instances (collision case). The only information gathered from the device is whether a fault occurred when processing a chosen plaintext.","Title: Enhancing COPACOBANA for advanced applications in cryptography and cryptanalysis\nYear: 2008\n\nAbstract: Cryptanalysis of symmetric and asymmetric ciphers is a challenging task due to the enormous amount of involved computations. To tackle this computa- tional complexity, usually the employment of special- purpose hardware is considered as best approach. We have built a massively parallel cluster system (COPA- COBANA) based on low-cost FPGAs as a cost-efficient platform primarily targeting cryptanalytical operations with these high computational efforts but low communi- cation and memory requirements. However, some par- allel applications in the field of cryptography are too complex for low-cost FPGAs and also require the avail- ability of at least moderate communication and memory facilities. Particularly, this holds true for arithmetic intensive application as well as ones with a highly com- plex data flow. In this contribution, we describe a novel architecture for a more versatile and reliable COPACOBANA ca- pable to host advanced cryptographic applications like high-performance digital signature generation accord- ing to the Elliptic Curve Digital Signature Algorithm (ECDSA) and integer factorization based on the Ellip- tic Curve Method (ECM). In addition to that, the new cluster design allows even to run more supercomputing applications beyond the field of cryptography.","Title: Security analysis of index-based syndrome coding for PUF-based key generation\nYear: 2015\n\nAbstract: Physical Unclonable Functions (PUFs) as secure providers for cryptographic keys have gained significant research interest in recent years. Since plain PUF responses are typically unreliable, error-correcting mechanisms are employed to transform a fuzzy PUF response into a deterministic cryptographic key. In this context, Index-Based Syndrome Coding (IBS) has been reported as being provably secure in case of identical and independently distributed PUF responses and is therefore an interesting option to implement a highly secure key provider. In this paper we analyze the security of IBS in combination with a k-sum PUF as proposed at CHES 2011. Since for a k-sum PUF the assumption of identical and independently distributed responses does not hold, the notion of leaked bits was introduced at CHES 2011 to capture the security of such constructions. Based on a refined analysis using hamming distance characterization and machine learning techniques, we show that the entropy of the key obtained is significantly lower than expected. More precisely, we obtained from our findings that even the construction from CHES with the highest security claims only achieves a bit entropy rate of 0.39.","Title: Utilizing hard cores of modern FPGA devices for high-performance cryptography\nYear: 2011\n\nAbstract: This article presents a unique design approach for the implementation of standardized symmetric and asymmetric cryptosystems\n on modern FPGA devices. In contrast to many other FPGA implementations that algorithmically optimize the cryptosystems for\n being optimally placed in the generic array logic, our primary implementation goal is to shift as many cryptographic operations\n as possible into specific hard cores that have become available on many reconfigurable devices. For example, some of these\n dedicated functions are designed to provide large blocks of memory or fast arithmetic functions for Digital Signal Processing\n applications that can also be adopted for efficient cryptographic implementations. Based on these dedicated functions, we\n present specific design approaches that enable a performance for the symmetric AES block cipher (FIPS 197) of up to 55 GBit/s\n and a throughput of more than 30.000 scalar multiplications per second for asymmetric Elliptic Curve Cryptography over NIST’s\n P-224 prime (FIPS 186-3).","Title: Affine Equivalence and its Application to Tightening Threshold Implementations.\nYear: 2015\n\nAbstract: Motivated by the development of Side-Channel Analysis SCA countermeasures which can provide security up﾿to a certain order, defeating higher-order attacks has become amongst the most challenging issues. For instance, Threshold Implementation TI which nicely solves the problem of glitches in masked hardware designs is able to avoid first-order leakages. Hence, its extension to higher orders aims at counteracting SCA attacks at higher orders, that might be limited to univariate scenarios. Although with respect to the number of traces as well as sensitivity to noise the higher the order, the harder it is to mount the attack, a d-order TI design is vulnerable to an attack at order $$d+1$$d+1. In this work we look at the feasibility of higher-order attacks on first-order TI from another perspective. Instead of increasing the order of resistance by employing higher-order TIs, we go toward introducing structured randomness into the implementation. Our construction, which is a combination of masking and hiding, is dedicated to TI designs and deals with the concept of \\\"affine equivalence\\\" of Boolean functions. Such a combination hardens a design practically against higher-order attacks so that these attacks cannot be successfully mounted. We show that the area overhead of our construction is paid off by its ability to avoid higher-order leakages to be practically exploitable.","Title: Implementing Curve25519 for Side-Channel-Protected Elliptic Curve Cryptography.\nYear: 2015\n\nAbstract: For security-critical embedded applications Elliptic Curve Cryptography (ECC) has become the predominant cryptographic system for efficient key agreement and digital signatures. However, ECC still involves complex modular arithmetic that is a particular burden for small processors. In this context, Bernstein proposed the highly efficient ECC instance Curve25519 that particularly enables efficient software implementations at a security level comparable to AES-128 with inherent resistance to simple power analysis (SPA) and timing attacks. In this work, we show that Curve25519 is likewise competitive on FPGAs even when countermeasures to thwart side-channel power analysis are included. Our basic multicore DSP-based architectures achieves a maximal performance of more than 32,000 point multiplications per second on a Xilinx Zynq 7020 FPGA. Including a mix of side-channel countermeasures to impede simple and differential power analysis, we still achieve more than 27,500 point multiplications per second with a moderate increase in logic resources.","Title: Implementing QC-MDPC McEliece Encryption\nYear: 2015\n\nAbstract: With respect to performance, asymmetric code-based cryptography based on binary Goppa codes has been reported as a highly interesting alternative to RSA and ECC. A major drawback is still the large keys in the range between 50 and 100KB that prevented real-world applications of code-based cryptosystems so far. A recent proposal by Misoczki et al. showed that quasi-cyclic moderate-density parity-check (QC-MDPC) codes can be used in McEliece encryption, reducing the public key to just 0.6KB to achieve an 80-bit security level. In this article, we provide optimized decoding techniques for MDPC codes and survey several efficient implementations of the QC-MDPC McEliece cryptosystem. This includes high-speed and lightweight architectures for reconfigurable hardware, efficient coding styles for ARM’s Cortex-M4 microcontroller, and novel high-performance software implementations that fully employ vector instructions. Finally, we conclude that McEliece encryption in combination with QC-MDPC codes not only enables high-performance implementations but also allows for lightweight designs on a wide range of different platforms.","Title: Practical Lattice-Based Digital Signature Schemes\nYear: 2015\n\nAbstract: Digital signatures are an important primitive for building secure systems and are used in most real-world security protocols. However, almost all popular signature schemes are either based on the factoring assumption (RSA) or the hardness of the discrete logarithm problem (DSA/ECDSA). In the case of classical cryptanalytic advances or progress on the development of quantum computers, the hardness of these closely related problems might be seriously weakened. A potential alternative approach is the construction of signature schemes based on the hardness of certain lattice problems that are assumed to be intractable by quantum computers. Due to significant research advancements in recent years, lattice-based schemes have now become practical and appear to be a very viable alternative to number-theoretic cryptography. In this article, we focus on recent developments and the current state of the art in lattice-based digital signatures and provide a comprehensive survey discussing signature schemes with respect to practicality. Additionally, we discuss future research areas that are essential for the continued development of lattice-based cryptography.","Title: IND-CCA Secure Hybrid Encryption from QC-MDPC Niederreiter.\nYear: 2016\n\nAbstract: QC-MDPC McEliece attracted significant attention as promising alternative public-key encryption scheme believed to be resistant against quantum computing attacks. Compared to binary Goppa codes, it achieves practical key sizes and was shown to perform well on constrained platforms such as embedded microcontrollers and FPGAs. However, so far none of the published QC-MDPC McEliece/Niederreiter implementations provide indistinguishability under chosen plaintext or chosen ciphertext attacks. Common ways for the McEliece and Niederreiter encryption schemes to achieve IND-CPA/IND-CCA security are surrounding constructions that convert them into secured schemes. In this work we take a slightly different approach presenting 1 an efficient implementation of QC-MDPC Niederreiter for ARM Cortex-M4 microcontrollers and 2 the first implementation of Persichetti's IND-CCA hybrid encryption scheme from PQCrypto'13 instantiated with QC-MDPC Niederreiter for key encapsulation and AES-CBC/AES-CMAC for data encapsulation. Both implementations achieve practical performance for embedded microcontrollers, at 80-bit security hybrid encryption takes 16.5ï¾źms, decryption 111ï¾źms and key-generation 386.4ï¾źms.","Title: New ASIC/FPGA Cost Estimates for SHA-1 Collisions\nYear: 2015\n\nAbstract: SHA-1 remains, till date, the most widely used hash function, in spite of several successful cryptanalytic attacks against it. These attacks, however, remain impractical due to high computation complexity and associated cost. We endeavor to do cost-time product estimation for an attack by the aid of application-specific hardware acceleration. This work proposes an Application-Specific Instruction-set Processor (ASIP), named Cracken. Cracken is aimed to efficiently realize near collision attack on SHA-1. The estimations of the physical attack complexity is done using 65nm standard CMOS technology and commercial FPGA devices. It is estimated, with post-layout simulations, that Stevens' differential attack with an estimated complexity of 2^57.5, can be executed in 46 days using 4096 Cracken cores at a cost of Euros 15m. Estimation for real collision with complexity 2^61 is also done. Our cost-time estimates reveal that an FPGA-based attack is more efficient compared to ASIC. Previously reported SHA-1 attacks based on ASIC and cloud computing platforms are also compiled and benchmarked for reference.","Title: Bridging the Gap: Advanced Tools for Side-Channel Leakage Estimation beyond Gaussian Templates and Histograms.\nYear: 2016\n\nAbstract: The accuracy and the fast convergence of a leakage model are both essential components for the efficiency of side-channel analysis. Thus for efficient leakage estimation an evaluator is requested to pick a Probability Density Function (PDF) that constitutes the optimal trade-off between both aspects. In the case of parametric estimation, Gaussian templates are a common choice due to their fast convergence, given that the actual leakages follow a Gaussian distribution (as in the case of an unprotected device). In contrast, histograms and kernel-based estimations are examples for non-parametric estimation that are capable to capture any distribution (even that of a protected device) at a slower convergence rate.","Title: High-Performance and Lightweight Lattice-Based Public-Key Encryption.\nYear: 2016\n\nAbstract: In the emerging Internet of Things, lightweight public-key cryptography is an essential component for many cost-efficient security solutions. Since conventional public-key schemes, such as ECC and RSA, remain expensive and energy hungry even after aggressive optimization, this work investigates a possible alternative. In particular, we show the practical potential of replacing the Gaussian noise distribution in the Ring-LWE based encryption scheme by Lindner and Peikert/Lyubashevsky et al. with a binary distribution. When parameters are carefully chosen, our construction is resistant against any state-of-the-art cryptanalytic techniques (e.g., attacks on original Ring-LWE or NTRU) and suitable for low-cost scenarios. In the end, our scheme can enable public-key encryption even on very small and low-cost 8-bit (ATXmega128) and 32-bit (Cortex-M0) microcontrollers.","Title: Secure architectures of future emerging cryptography SAFEcrypto.\nYear: 2016\n\nAbstract: Funded under the European Union's Horizon 2020 research and innovation programme, SAFEcrypto will provide a new generation of practical, robust and physically secure post-quantum cryptographic solutions that ensure long-term security for future ICT systems, services and applications. The project will focus on the remarkably versatile field of Lattice-based cryptography as the source of computational hardness, and will deliver optimised public key security primitives for digital signatures and authentication, as well identity based encryption (IBE) and attribute based encryption (ABE). This will involve algorithmic and design optimisations, and implementations of lattice-based cryptographic schemes addressing cost, energy consumption, performance and physical robustness. As the National Institute of Standards and Technology (NIST) prepares for the transition to a post-quantum cryptographic suite B, urging organisations that build systems and infrastructures that require long-term security to consider this transition in architectural designs; the SAFEcrypto project will provide Proof-of-concept demonstrators of schemes for three practical real-world case studies with long-term security requirements, in the application areas of satellite communications, network security and cloud. The goal is to affirm Lattice-based cryptography as an effective replacement for traditional number-theoretic public-key cryptography, by demonstrating that it can address the needs of resource-constrained embedded applications, such as mobile and battery-operated devices, and of real-time high performance applications for cloud and network management infrastructures.","Title: Information reconciliation schemes in physical-layer security: A survey.\nYear: 2016\n\nAbstract: Information reconciliation is an essential part of physical-layer based key agreement. It enables the equalization of similar, but disagreeing channel observations of respective communicating parties. Due to a broad variety of underlying mathematical constructions and a large parameter space, there is a lack of systematic classification of the individual schemes. To address this issue, we present an extensive survey of existing protocols. Furthermore, we derive a generalized layer model for information reconciliation, show how existing approaches map to this model and how it supports future research work in this field.","Title: Sixth International Workshop on Trustworthy Embedded Devices (TrustED 2016).\nYear: 2016\n\nAbstract: The Internet of Things (IoT) is expected to become a global information and communication infrastructure for cyber physical systems and to bring numerous value-added services for modern society. However, the integration of heterogeneous devices and service models into a cohesive system significantly increases the complexity of design and deployment and introduces the new challenges for the security of systems and processed as well as the privacy of the collected data. The Workshop on Trustworthy Embedded Devices (TrustED) addresses all aspects of security and privacy related to embedded systems and the IoT. TrustED 2016 is a continuation of previous workshops in this series, which were held in conjunction with ESORICS 2011, IEEE Security & Privacy 2012, ACM CCS 2013, ACM CCS 2014, and ACM CCS 2015 (see http://www.trusted-workshop.de for details). The goal of this workshop is to bring together experts from academia and research institutes, industry, and government in the field of security and privacy in cyber physical systems to discuss and investigate the problems, challenges, and recent scientific and technological developments.","Title: On the Energy Cost of Channel Based Key Agreement.\nYear: 2016\n\nAbstract: Besides security, energy consumption is a major concern for devices in the Internet of Things (IoT). We compare the energy consumption of two key agreement schemes -- Channel-Based Key Agreement (CBKA) and Elliptic Curve Diffie-Hellman (ECDH) -- in the IoT setting, using Wi-Fi as wireless communication interface. While ECDH is a well-studied protocol, CBKA has received attention only in recent years. Several publications proposed CBKA as a low-energy alternative to ECDH, but they did not address the energy cost of communication. For a fair comparison, we implemented the schemes on a 32-bit ARM Cortex M3-based IoT platform and measured the respective energy consumption for computation and communication. Our results show that the limiting factor for CBKA over Wi-Fi is the energy cost of communication, in particular the cost of acquiring the Received Signal Strength Indicator (RSSI) values. Even in an optimal scenario, CBKA must not measure more than ca. 300 RSSI values to be more energy efficient than ECDH. This is at most 1/5 of RSSI values required by CBKA implementations reported in the literature. As an optimization, we present a refined CBKA protocol which can save up to 25% of the energy compared to existing protocols by exploiting inherent data exchanges for entropy extraction.","Title: Practical CCA2-Secure and Masked Ring-LWE Implementation.\nYear: 2018\n\nAbstract: During the last years public-key encryption schemes based on the hardness of ring-LWE have gained significant popularity. For real-world security applications assuming strong adversary models, a number of practical issues still need to be addressed. In this work we thus present an instance of ring-LWE encryption that is protected against active attacks (i.e., adaptive chosen-ciphertext attacks) and equipped with countermeasures against side-channel analysis. Our solution is based on a postquantum variant of the Fujisaki-Okamoto (FO) transform combined with provably secure first-order masking. To protect the key and message during decryption, we developed a masked binomial sampler that secures the re-encryption process required by FO. Our work shows that CCA2-secured RLWE-based encryption can be achieved with reasonable performance on constrained devices but also stresses that the required transformation and handling of decryption errors implies a performance overhead that has been overlooked by the community so far. With parameters providing 233 bits of quantum security, our implementation requires 4,176,684 cycles for encryption and 25,640,380 cycles for decryption with masking and hiding countermeasures on a Cortex-M4F. The first-order security of our masked implementation is also practically verified using the non-specific t-test evaluation methodology.","Title: Hiding Higher-Order Side-Channel Leakage - Randomizing Cryptographic Implementations in Reconfigurable Hardware.\nYear: 2017\n\nAbstract: First-order secure Threshold Implementations (TI) of symmetric cryptosystems provide provable security at a moderate overhead; yet attacks using higher-order statistical moments are still feasible. Cryptographic instances compliant to Higher-Order Threshold Implementation (HO-TI) can prevent such attacks, however, usually at unacceptable implementation costs. As an alternative concept we investigate in this work the idea of dynamic hardware modification, i.e., random changes and transformations of cryptographic implementations in order to render higher-order attacks on first-order TI impractical. In a first step, we present a generic methodology which can be applied to (almost) every cryptographic implementation. In order to investigate the effectiveness of our proposed strategy, we use an instantiation of our methodology that adapts ideas from White-Box Cryptography and applies this construction to a first-order secure TI. Further, we show that dynamically updating cryptographic implementations during operation provides the ability to avoid higher-order leakages to be practically exploitable.","Title: A grain in the silicon: SCA-protected AES in less than 30 slices\nYear: 2016\n\nAbstract: AES is the predominant block cipher used worldwide in many cryptographic applications. Despite of the wealth of already available implementations, we here introduce an ultra-lightweight AES-128 implementation specifically tailored for reconfigurable hardware. Our basic proposal presents a full AES-128 providing 9.12 Mbit/s throughput and occupying just 21 slices of a Spartan-6 and no additional memories. We also show that this architecture almost, inherently supports shuffling as side-channel countermeasure and provide results of a practical evaluation. Our protected design fits into 24 slices providing 7.82 Mbit/s throughput. Finally, we present a complete AES core that combines previous results with random number generation which fits 28 slices at 4.35 Mbit/s throughput.","Title: Secure and Private, yet Lightweight, Authentication for the IoT via PUF and CBKA.\nYear: 2016\n\nAbstract: The Internet of Things IoT is boon and bane. It offers great potential for new business models and ecosystems, but raises major security and privacy concerns. Because many IoT systems collect, process, and store personal data, a secure and privacy-preserving identity management is of utmost significance. Yet, strong resource limitations of IoT devices render resource-hungry public-key cryptography infeasible. Additionally, the security model of IoT enforces solutions to work under memory-leakage attacks. Existing constructions address either the privacy issue or the lightweightness, but not both. Our work contributes towards bridging this gap by combining physically unclonable functions PUFs and channel-based key agreement CBKA: i We show a flaw in a PUF-based authentication protocol, when outsider chosen perturbation security cannot be guaranteed. ii We present a solution to this flaw by introducing CBKA with an improved definition. iii We propose a provably secure and lightweight authentication protocol by combining PUFs and CBKA.","Title: Strong 8-bit Sboxes with efficient masking in hardware extended version.\nYear: 2017\n\nAbstract: Block ciphers are arguably the most important cryptographic primitive in practice. While their security against mathematical attacks is rather well understood, physical threats such as side-channel analysis (SCA) still pose a major challenge for their security. An effective countermeasure to thwart SCA is using a cipher representation that applies the threshold implementation (TI) concept. However, there are hardly any results available on how this concept can be adopted for block ciphers with large (i.e., 8-bit) Sboxes. In this work we provide a systematic analysis on and search for 8-bit Sbox constructions that can intrinsically feature the TI concept, while still providing high resistance against cryptanalysis. Our study includes investigations on Sboxes constructed from smaller ones using Feistel, SPN, or MISTY network structures. As a result, we present a set of new Sboxes that not only provide strong cryptographic criteria, but are also optimized for TI. We believe that our results will find an inspiring basis for further research on high-security block ciphers that intrinsically feature protection against physical attacks.","Title: Cryptography for Next Generation TLS: Implementing the RFC 7748 Elliptic Curve448 Cryptosystem in Hardware.\nYear: 2017\n\nAbstract: With RFC 7748 the two elliptic curves Curve25519 and Curve448 were proposed for the next generation of TLS. Both curves were designed and optimized purely for software implementation; their implementation in hardware or physical protection against side-channel attacks were not considered in the design phase. Recently, it has been shown that for Curve25519 an efficient implementations in hardware along with side-channel protection is feasible -- yet results for the high-security Curve448 are missing. In this work we demonstrate that Curve448 can indeed be efficiently and securely implemented in hardware. We present a novel architecture for Curve448 that can compute more than 1000 point multiplications per second with 1580 logic slices and 33 DSP units of a Xilinx XC7Z020 FPGA.","Title: Lattice-based cryptography: From reconfigurable hardware to ASIC\nYear: 2016\n\nAbstract: As progress in technology is predicted to make quantum computers available in the next few decades, it is imperative to design public-key cryptosystems capable of resisting attacks that are perceived to be possible using these new platforms. Lattice-based cryptography is one of the most promising quantum-safe candidates being considered to replace current public-key systems. Thus, it has been extensively evaluated in terms of both hardware and software implementations. However, to date lattice-based hardware designs have only been proposed for reconfigurable FPGA devices, leaving ASIC designs unexplored. In this paper, we present and discuss the main challenges and opportunities in implementing lattice-based algorithms on dedicated ASIC devices.","Title: ParTI: Towards Combined Hardware Countermeasures against Side-Channeland Fault-Injection Attacks\nYear: 2016\n\nAbstract: Side-channel analysis and fault-injection attacks are known as major threats to any cryptographic implementation. Hardening cryptographic implementations with appropriate countermeasures is thus essential before they are deployed in the wild. However, countermeasures for both threats are of completely different nature: Side-channel analysis is mitigated by techniques that hide or mask key-dependent information while resistance against fault-injection attacks can be achieved by redundancy in the computation for immediate error detection. Since already the integration of any single countermeasure in cryptographic hardware comes with significant costs in terms of performance and area, a combination of multiple countermeasures is expensive and often associated with undesired side effects. In this work, we introduce a countermeasure for cryptographic hardware implementations that combines the concept of a provably-secure masking scheme i.e., threshold implementation with an error detecting approach against fault injection. As a case study, we apply our generic construction to the lightweight LED cipher. Our LED instance achieves first-order resistance against side-channel attacks combined with a fault detection capability that is superior to that of simple duplication for most error distributions at an increased area demand of 12﾿%.","Title: High-Performance Ideal Lattice-Based Cryptography on 8-Bit AVR Microcontrollers\nYear: 2017\n\nAbstract: Over recent years lattice-based cryptography has received much attention due to versatile average-case problems like Ring-LWE or Ring-SIS that appear to be intractable by quantum computers. In this work, we evaluate and compare implementations of Ring-LWE encryption and the bimodal lattice signature scheme (BLISS) on an 8-bit Atmel ATxmega128 microcontroller. Our implementation of Ring-LWE encryption provides comprehensive protection against timing side-channels and takes 24.9ms for encryption and 6.7ms for decryption. To compute a BLISS signature, our software takes 317ms and 86ms for verification. These results underline the feasibility of lattice-based cryptography on constrained devices.","Title: Confident Leakage Assessment - A Side-Channel Evaluation Framework Based On Confidence Intervals\nYear: 2018\n\nAbstract: Cryptographic devices that potentially operate in hostile physical environments need to be secured against side channel attacks. In order to ensure the effectiveness of the required countermeasures, scientists, developers, and evaluators need efficient methods to test the security level of a device. In this paper we propose a new framework based on confidence intervals that extends established t-test based approaches for test vector leakage assessment (TVLA). In comparison to previous TVLA approaches the new methodology does not only enable the detection of leakage but can also assert its absence. The framework is robust against noise in the evaluation system and thereby avoids false negatives. These improvements can be achieved without overhead in measurement complexity and with a minimum of additional computational costs compared to previous approaches.We evaluate our method under realistic conditions by applying it to a protected implementation of AES.","Title: Physical Protection of Lattice-Based Cryptography: Challenges and Solutions.\nYear: 2018\n\nAbstract: The impending realization of scalable quantum computers will have a significant impact on today's security infrastructure. With the advent of powerful quantum computers public key cryptographic schemes will become vulnerable to Shor's quantum algorithm, undermining the security current communications systems. Post-quantum (or quantum-resistant) cryptography is an active research area, endeavoring to develop novel and quantum resistant public key cryptography. Amongst the various classes of quantum-resistant cryptography schemes, lattice-based cryptography is emerging as one of the most viable options. Its efficient implementation on software and on commodity hardware has already been shown to compete and even excel the performance of current classical security public-key schemes. This work discusses the next step in terms of their practical deployment, i.e., addressing the physical security of lattice-based cryptographic implementations. We survey the state-of-the-art in terms of side channel attacks (SCA), both invasive and passive attacks, and proposed countermeasures. Although the weaknesses exposed have led to countermeasures for these schemes, the cost, practicality and effectiveness of these on multiple implementation platforms, however, remains under-studied.","Title: Exploring RFC 7748 for Hardware Implementation: Curve25519 and Curve448 with Side-Channel Protection\nYear: 2018\n\nAbstract: Recent revelations on manipulations and back-doors in modern ECC have initiated the revision of existing schemes and led to the selection of two new solutions for next-generation TLS proposed in RFC 7748: Curve25519 and Curve448. Unfortunately, both curves were designed and optimized primarily for software implementations; their implementation in hardware and physical protection against SCA has been neglected during the design phase. In this work, we demonstrate that both curves can indeed be efficiently and securely mapped to hardware structures of modern FPGAs while including advanced protection mechanisms against physical attacks and still providing high performance and throughput. In particular, our Curve25519 architecture provides more than 1 700 point multiplications per second, using only 1 006 logic slices (LSs) and 20 digital signal processors (DSPs) of a mid-range Xilinx XC7Z020 FPGA. Furthermore, our Curve448 architecture still achieves more than 600 operations per second at a significantly higher security level of 224 bits, using not more than 1 985 LSs and 33 DSPs on the same device. In addition, we performed a practical, test-based leakage assessment for both architectures. More precisely, we investigated the detection of scalar- and base-point-dependable leakage individually while our designs were incorporated scalar blinding and point randomization countermeasures. Eventually, our findings prove with high confidence, that we cannot detect any scalar- and base-point-dependable leakage even after evaluating 1 000 000 power measurements.","Title: Profiled Power Analysis Attacks Using Convolutional Neural Networks with Domain Knowledge.\nYear: 2018\n\nAbstract: Evaluation of cryptographic implementations against profiled side-channel attacks plays a fundamental role in security testing nowadays. Recently, deep neural networks and especially Convolutional Neural Networks have been introduced as a new tool for that purpose. Although having several practical advantages over common Gaussian templates such as intrinsic feature extraction, the deep-learning-based profiling techniques proposed in literature still require a suitable leakage model for the implementation under test. Since this is a crucial task, we are introducing domain knowledge to exploit the full power of approximating very complex functions with neural networks. By doing so, we are able to attack the secret key directly without any assumption about the leakage behavior. Our experiments confirmed that our method is much more efficient than state-of-the-art profiling approaches when targeting an unprotected hardware and a protected software implementation of the AES.","Title: Evaluation of Lattice-Based Signature Schemes in Embedded Systems\nYear: 2018\n\nAbstract: Lattice-based cryptography is a promising candidate and remedy in public-key cryptography in case quantum computers become feasible or a major breakthrough in solving the factorization problem or the discrete logarithm problem is achieved. Due to ongoing research in this field, many schemes still lack implementations that examine their practicability, especially for embedded systems. In this work we discuss the potential of lattice-based signature schemes for practical applications on constrained devices in a post-quantum era. We focus on the schemes GLP, BLISS, and Dilithium and discuss their unique properties as well as challenges regarding their implementation on embedded devices. In this regard we present and review optimized implementations of these schemes for ARM Cortex-M4 microcontrollers to evaluate the practical performance of the schemes.","Title: Practical lattice-based cryptography: a signature scheme for embedded systems\nYear: 2012\n\nAbstract: Nearly all of the currently used and well-tested signature schemes (e.g. RSA or DSA) are based either on the factoring assumption or the presumed intractability of the discrete logarithm problem. Further algorithmic advances on these problems may lead to the unpleasant situation that a large number of schemes have to be replaced with alternatives. In this work we present such an alternative --- a signature scheme whose security is derived from the hardness of lattice problems. It is based on recent theoretical advances in lattice-based cryptography and is highly optimized for practicability and use in embedded systems. The public and secret keys are roughly 12000 and 2000 bits long, while the signature size is approximately 9000 bits for a security level of around 100 bits. The implementation results on reconfigurable hardware (Spartan/Virtex 6) are very promising and show that the scheme is scalable, has low area consumption, and even outperforms some classical schemes.","Title: Compact implementation and performance evaluation of block ciphers in ATtiny devices\nYear: 2012\n\nAbstract: The design of lightweight block ciphers has been a very active research topic over the last years. However, the lack of comparative source codes generally makes it hard to evaluate the extent to which implementations of different ciphers actually reach their low-cost goals on various platforms. This paper reports on an initiative aiming to relax this issue. First, we provide implementations of 12 block ciphers on an ATMEL AVR ATtiny45 8-bit microcontroller, and make the corresponding source code available on a web page. All implementations are made public under an open-source license. Common interfaces and design goals are followed by all designers to achieve comparable implementation results. Second, we evaluate performance figures of our implementations with respect to different metrics, including energy-consumption measurements and show our improvements compared to existing implementations.","Title: Standard Lattice-Based Key Encapsulation on Embedded Devices.\nYear: 2018\n\nAbstract: Lattice-based cryptography is one of the most promising candidates being considered to replace current public-key systems in the era of quantum computing. In 2016, Bos et al. proposed the key exchange scheme FrodoCCS, that is also a submission to the NIST post-quantum standardization process, modified as a key encapsulation mechanism (FrodoKEM). The security of the scheme is based on standard lattices and the learning with errors problem. Due to the large parameters, standard latticebased schemes have long been considered impractical on embedded devices. The FrodoKEM proposal actually comes with parameters that bring standard lattice-based cryptography within reach of being feasible on constrained devices. In this work, we take the final step of efficiently implementing the scheme on a low-cost FPGA and microcontroller devices and thus making conservative post-quantum cryptography practical on small devices. Our FPGA implementation of the decapsulation (the computationally most expensive operation) needs 7,220 look-up tables (LUTs), 3,549 flip-flops (FFs), a single DSP, and only 16 block RAM modules. The maximum clock frequency is 162 MHz and it takes 20.7 ms for the execution of the decapsulation. Our microcontroller implementation has a 66% reduced peak stack usage in comparison to the reference implementation and needs 266 ms for key pair generation, 284 ms for encapsulation, and 286 ms for decapsulation. Our results contribute to the practical evaluation of a post-quantum standardization candidate.","Title: Applications of machine learning techniques in side-channel attacks: a survey\nYear: 2020\n\nAbstract: With increasing expansion of the Internet of Things, embedded devices equipped with cryptographic modules become an important factor to protect sensitive data. Even though the employed algorithms in such devices are mathematically secure in theory, adversaries may still be able to compromise them by means of side-channel attacks. In power-based side-channel attacks, the instantaneous power consumption of the target is analyzed with statistical tools to draw conclusions about the secret keys that are used. There is a recent line of work that additionally makes use of techniques from the machine learning domain to attack cryptographic implementations. Since a complete review of this emerging field has not been done so far, this research aims to survey the current state of the art. We use a target-based classification to differentiate published work and drive general conclusions according to a common machine learning workflow. Furthermore, we outline the relationship between traditional power analysis techniques and machine learning-based attacks. This enables researchers to gain a better understanding of the topic in order to design new attack methods as well as potential countermeasures.","Title: Securing Cryptographic Circuits by Exploiting Implementation Diversity and Partial Reconfiguration on FPGAs\nYear: 2019\n\nAbstract: Adaptive and reconfigurable systems such as Field Programmable Gate Arrays (FPGAs) play an integral part of many complex embedded platforms. This implies the capability to perform runtime changes to hardware circuits on demand. In this work, we make use of this feature to propose a no-vel countermeasure against physical attacks of cryptographic implementations. In particular, we leverage exploration of the implementation space on FPGAs to create various circuits with different hardware layouts from a single design of the Advanced Encryption Standard (AES), that are dynamically exchanged during device operation. We provide evidence from practical experiments based on a modern Xilinx ZYNQ UltraScale+ FPGA that our approach increases the resistance against physical attacks by at least factor two. Furthermore, the genericness of our approach allows an easy adaption to other algorithms and combination with other countermeasures.","Title: Efficiently Masking Binomial Sampling at Arbitrary Orders for Lattice-Based Crypto\nYear: 2019\n\nAbstract: With the rising popularity of lattice-based cryptography, the Learning with Errors (LWE) problem has emerged as a fundamental core of numerous encryption and key exchange schemes. Many LWE-based schemes have in common that they require sampling from a discrete Gaussian distribution which comes with a number of challenges for the practical instantiation of those schemes. One of these is the inclusion of countermeasures against a physical side-channel adversary. While several works discuss the protection of samplers against timing leaks, only few publications explore resistance against other side-channels, e.g., power. The most recent example of a protected binomial sampler (as used in key encapsulation mechanisms to sufficiently approximate Gaussian distributions) from CHES 2018 is restricted to a first-order adversary and cannot be easily extended to higher protection orders.","Title: Write Me and I'll Tell You Secrets - Write-After-Write Effects On Intel CPUs.\nYear: 2022\n\nAbstract: There is a long history of side channels in the memory hierarchy of modern CPUs. Especially the cache side channel is widely used in the context of transient execution attacks and covert channels. Therefore, many secure cache architectures have been proposed. Most of these architectures aim to make the construction of eviction sets infeasible by randomizing the address-to-cache mapping. In this paper, we investigate the peculiarities of write instructions in recent CPUs. We identify Write+Write, a new side channel on Intel CPUs that leaks whether two addresses contend for the same cache set. We show how Write+Write can be used for rapid construction of eviction sets on current cache architectures. Moreover, we replicate the Write+Write effect in gem5 and demonstrate on the example of ScatterCache how it can be exploited to efficiently attack state-of-the-art cache randomization schemes. In addition to the Write+Write side channel, we show how Write-After-Write effects can be leveraged to efficiently synchronize covert channel communication across CPU cores. This yields the potential for much more stealthy covert channel communication than before."],"string":"[\n \"Title: Cryptanalysis with COPACOBANA\\nYear: 2008\\n\\nAbstract: Cryptanalysis of ciphers usually involves massive computations. The security parameters of cryptographic algorithms are commonly chosen so that attacks are infeasible with available computing resources. This contribution presents a variety of cryptanalytical applications utilizing the COPACOBANA (Cost-Optimized Parallel Code Breaker) machine which is a high-performance, low-cost cluster consisting of 120 Field Programmable Gate Arrays (FPGA). COPACOBANA appears to be the only such reconfigurable parallel FPGA machine optimized for code breaking tasks reported in the open literature. Depending on the actual algorithm, the parallel hardware architecture can outperform conventional computers by several orders of magnitude. In this work, we will focus on novel implementations of cryptanalytical algorithms, utilizing the impressive computational power of COPACOBANA. We describe various exhaustive key search attacks on symmetric ciphers and demonstrate an attack on a security mechanism employed in the electronic passport. Furthermore, we describe time-memory tradeoff techniques which can, e.g., be used for attacking the popular A5/1 algorithm used in GSM voice encryption. In addition, we introduce efficient implementations of more complex cryptanalysis on asymmetric cryptosystems, e.g., Elliptic Curve Cryptosystems (ECC) and number co-factorization for RSA.\",\n \"Title: Kryptografie auf programmierbarer Hardware.\\nYear: 2010\\n\\nAbstract: Zusammenfassung Sicherheitsmechanismen und kryptografische Verfahren werden mittlerweile in sehr vielen eingebetteten Systemen eingesetzt.\\n Beim Entwurf solcher Systeme ist neben dem Schutz von Daten und der Nachrichtenauthentizität oft zu berücksichtigen, dass\\n die implementierten Sicherheitsmechanismen keine Einschränkungen der Leistungsfähigkeit der Systeme zur Folge haben. Der Beitrag\\n beleuchtet, wie derartige Anforderungen mit Hilfe von programmierbarer Hardware umgesetzt werden können.\",\n \"Title: Enhanced Lattice-Based Signatures on Reconfigurable Hardware\\nYear: 2014\\n\\nAbstract: The recent Bimodal Lattice Signature Scheme Bliss showed that lattice-based constructions have evolved to practical alternatives to RSA or ECC. Besides reasonably small signatures with 5600 bits for a 128-bit level of security, Bliss enables extremely fast signing and signature verification in software. However, due to the complex sampling of Gaussian noise with high precision, it is not clear whether this scheme can be mapped efficiently to embedded devices. Even though the authors of Bliss also proposed a new sampling algorithm using Bernoulli variables this approach is more complex than previous methods using large precomputed tables. The clear disadvantage of using large tables for high performance is that they cannot be used on constrained computing environments, such as FPGAs, with limited memory. In this work we thus present techniques for an efficient Cumulative Distribution Table CDT based Gaussian sampler on reconfigurable hardware involving Peikert's convolution lemma and the Kullback-Leibler divergence. Based on our enhanced sampler design, we provide a first Bliss architecture for Xilinx Spartan-6 FPGAs that integrates fast FFT/NTT-based polynomial multiplication, sparse multiplication, and a Keccak hash function. Additionally, we compare the CDT with the Bernoulli approach and show that for the particular Bliss-I parameter set the improved CDT approach is faster with lower area consumption. Our core uses 2,431 slices, 7.5 BRAMs, and 6 DSPs and performs a signing operation in 126 μs on average. Verification takes even less with 70 μs.\",\n \"Title: Towards one cycle per bit asymmetric encryption: code-based cryptography on reconfigurable hardware\\nYear: 2012\\n\\nAbstract: Most advanced security systems rely on public-key schemes based either on the factorization or the discrete logarithm problem. Since both problems are known to be closely related, a major breakthrough in cryptanalysis tackling one of those problems could render a large set of cryptosystems completely useless. Code-based public-key schemes are based on the alternative security assumption that decoding generic linear binary codes is NP-complete. In the past, most researchers focused on the McEliece cryptosystem, neglecting the fact that the scheme by Niederreiter has some important advantages. Smaller keys, more practical plain and ciphertext sizes and less computations. In this work we describe a novel FPGA implementation of the Niederreiter scheme, showing that its advantages can result a very efficient design for an asymmetric cryptosystem that can encrypt more than 1.5 million plaintexts per seconds on a Xilinx Virtex-6 FPGA, outperforming all other popular public key cryptosystems by far.\",\n \"Title: Trojan Side-Channels: Lightweight Hardware Trojans through Side-Channel Engineering\\nYear: 2009\\n\\nAbstract: The general trend in semiconductor industry to separate design from fabrication leads to potential threats from untrusted integrated circuit foundries. In particular, malicious hardware components can be covertly inserted at the foundry to implement hidden backdoors for unauthorized exposure of secret information. This paper proposes a new class of hardware Trojans which intentionally induce physical side-channels to convey secret information. We demonstrate power side-channels engineered to leak information below the effective noise power level of the device. Two concepts of very small implementations of Trojan side-channels (TSC) are introduced and evaluated with respect to their feasibility on Xilinx FPGAs. Their lightweight implementations indicate a high resistance to detection by conventional test and inspection methods. Furthermore, the proposed TSCs come with a physical encryption property, so that even a successful detection of the artificially introduced side-channel will not allow unhindered access to the secret information.\",\n \"Title: DSPs, BRAMs, and a Pinch of Logic: Extended Recipes for AES on FPGAs\\nYear: 2010\\n\\nAbstract: We present three lookup-table-based AES implementations that efficiently use the BlockRAM and DSP units embedded within Xilinx Virtex-5 FPGAs. An iterative module outputs a 32-bit AES round column every clock cycle, with a throughput of 1.67 Gbit/s when processing two 128-bit inputs. This construct is then replicated four times to provide a complete AES round per cycle with 6.7 Gbit/s throughput when processing eight input streams. This, in turn, is replicated ten times for a fully unrolled design providing over 52 Gbit/s of throughput. We also present implementations of a BRAM-based AES key-expansion, CMAC, and CTR modes of operation. Results for designs where DSPs are replaced by regular logic are also presented. The combination and arrangement of the specialized embedded functions available in the FPGA allows us to implement our designs using very few traditional user logic elements such as flip-flops and lookup tables, yet still achieve these high throughputs. HDL source code, simulation testbenches, and software tool commands to reproduce reported results for the three AES variants and CMAC mode are made publicly available. Our contribution concludes with a discussion on comparing cipher implementations in the literature, and why these comparisons can be meaningless without a common reporting methodology, or within the context of a constrained target application.\",\n \"Title: PRINCE - A Low-Latency Block Cipher for Pervasive Computing Applications - Extended Abstract.\\nYear: 2012\\n\\nAbstract: This paper presents a block cipher that is optimized with respect to latency when implemented in hardware. Such ciphers are desirable for many future pervasive applications with real-time security needs. Our cipher, named PRINCE, allows encryption of data within one clock cycle with a very competitive chip area compared to known solutions. The fully unrolled fashion in which such algorithms need to be implemented calls for innovative design choices. The number of rounds must be moderate and rounds must have short delays in hardware. At the same time, the traditional need that a cipher has to be iterative with very similar round functions disappears, an observation that increases the design space for the algorithm. An important further requirement is that realizing decryption and encryption results in minimum additional costs. PRINCE is designed in such a way that the overhead for decryption on top of encryption is negligible. More precisely for our cipher it holds that decryption for one key corresponds to encryption with a related key. This property we refer to as alpha-reflection is of independent interest and we prove its soundness against generic attacks.\",\n \"Title: Efficient Hash Collision Search Strategies on Special-Purpose Hardware\\nYear: 2007\\n\\nAbstract: Hash functions play an important role in various cryptographic applications. Modern cryptography relies on a few but supposedly well analyzed hash functions which are mostly members of the so-called MD4-family. This work shows whether it is possible to significantly speedup collision search for MD4-family hash functions using special-purpose hardware. A thorough analysis of the computational requirements for MD4-family hash functions and corresponding collision attacks reveals that a microprocessor based architecture is best suited for the implementation of collision search algorithms. Consequently, we designed and implemented a (concerning MD4-family hash-functions) general-purpose microprocessor with minimal area requirements and, based on this, a full collision search unit. Comparing the performance characteristics of both ASICs with standard PC processors and clusters, it turns out that our design, massively parallelized, is nearly four times more cost-efficient than parallelized standard PCs. Although with further optimizations this factor can certainly be improved, we believe that special-purpose hardware does not provide a too significant benefit for hash collision search algorithms with respect to modern off-the-shelf general-purpose processors.\",\n \"Title: Ultra High Performance ECC over NIST Primes on Commercial FPGAs\\nYear: 2008\\n\\nAbstract: Elliptic Curve Cryptosystems (ECC) have gained increasing acceptance in practice due to their significantly smaller bit size of the operands compared to other public-key cryptosystems. Since their computational complexity is often lower than in the case of RSA or discrete logarithm schemes, ECC are often chosen for high performance public-key applications. However, despite a wealth of research regarding high-speed software and high-speed FPGA implementation of ECC since the mid 1990s, providing truly high-performance ECC on readily available (i.e., non-ASIC) platforms remains an open challenge. This holds especially for ECC over prime fields, which are often preferred over binary fields due to standards in Europe and the US.This work presents a new architecture for an FPGA-based ultra high performance ECC implementation over prime fields. Our architecture makes intensive use of the DSP blocks in modern FPGAs, which are embedded arithmetic units actually intended to accelerate digital signal processing algorithms. We describe a novel architecture and algorithms for performing ECC arithmetic and describe the actual implementation of standard compliant ECC based on the NIST primes P-224 and P-256. We show that ECC on Xilinx's Virtex-4 SX55 FPGA can be performed at a rate of more than 37,000 point multiplications per second. Our architecture outperforms all single-chip hardware implementations over prime fields in the open literature by a wide margin.\",\n \"Title: Full lattice basis reduction on graphics cards\\nYear: 2011\\n\\nAbstract: Recent lattice enumeration GPU implementations are very useful to find shortest vectors within a given lattice but are also highly dependent on a lattice basis reduction that still runs on a CPU. Therefore we present an implementation of a full lattice basis reduction that makes exclusive use of GPUs to close this gap. Hence, we show that GPUs are, as well, suited to apply lattice basis reduction algorithms that were merely of theoretical interest so far due to their enormous computational effort. We modified and optimized these algorithms to fit the architecture of graphics cards, in particular we focused on Givens Rotations and the All-swap reduction method. Eventually, our GPU implementation achieved a significant speed-up for given lattice challenges compared to the NTL implementation running on an CPU of about 18, providing at least the same reduction quality.\",\n \"Title: Smaller keys for code-based cryptography: QC-MDPC mceliece implementations on embedded devices\\nYear: 2013\\n\\nAbstract: In the last years code-based cryptosystems were established as promising alternatives for asymmetric cryptography since they base their security on well-known NP-hard problems and still show decent performance on a wide range of computing platforms. The main drawback of code-based schemes, including the popular proposals by McEliece and Niederreiter, are the large keys whose size is inherently determined by the underlying code. In a very recent approach, Misoczki et al. proposed to use quasi-cyclic MDPC (QC-MDPC) codes that allow for a very compact key representation. In this work, we investigate novel implementations of the McEliece scheme using such QC-MDPC codes tailored for embedded devices, namely a Xilinx Virtex-6 FPGA and an 8-bit AVR microcontroller. In particular, we evaluate and improve different approaches to decode QC-MDPC codes. Besides competitive performance for encryption and decryption on the FPGA, we achieved a very compact implementation on the microcontroller using only 4,800 and 9,600 bits for the public and secret key at 80 bits of equivalent symmetric security.\",\n \"Title: Parallel Computing with Low-Cost FPGAs: A Framework for COPACOBANA\\nYear: 2007\\n\\nAbstract: In many disciplines such as applied sciences or computer science, computationally challenging problems demand for extraordinary computing power, mostly provided by super computers or clusters of conventional desktop CPUs. During the last decides, several flavours of super computers have evolved. most of which are suitable for a specific type of problem. In general. dedicated clusters and super computers suffer from their extremely high cost per computation and are, due to the lack of cheap alternatives, currently the only possible solution to computational hard problems. More recently. emerging low-cost FPGAs tend to be a very cost-effective alternative to conventional CPUs for solving at least sonic of the computational hard problems such as those appearing in cryptanalysis and bio-informatics. In cryptanalysis, breaking symmetric or asymmetric ciphers is computationally extremely demanding. Since the security parameters (in particular the key length) of almost all practical crypto algorithms are chosen such that attacks with conventional computers are computationally infeasible. the only promising way to tackle existing ciphers (assuming no mathematical breakthrough) is to build Special-purpose hardware. Dedicating those machines to the task of cryptanalysis holds the promise of a dramatically improved cost-performance ratio so that breaking of commercial ciphers comes within reach. This contribution presents the realization of a very genetic framework for the COPACOBANA (Cost-Optimized Parallel Code Breaker) machine(1). COPACOBANA consists of up to 120 low-cost FPGAs and call be realized for US$ 10,000 while being able to outperform conventional computers by several orders in magnitude, depending oil the application. The presented framework allows for a simple distribution of parallelizable tasks and corresponding control mechanisms. With the framework at hand. the overhead and. as a consequence, the time to deploy custom made applications on the COPACOBANA platform is minimized. Exemplarily. we show how cryptanalytical applications can be based on top of the framework. resulting ill a very low cost per computation.\",\n \"Title: Towards Practical Lattice-Based Public-Key Encryption on Reconfigurable Hardware.\\nYear: 2013\\n\\nAbstract: With this work we provide further evidence that lattice-based cryptography is a promising and efficient alternative to secure embedded applications. So far it is known for solid security reductions but implementations of specific instances have often been reported to be too complex beyond any practicability. In this work, we present an efficient and scalable micro-code engine for Ring-LWE encryption that combines polynomial multiplication based on the Number Theoretic Transform (NTT), polynomial addition, subtraction, and Gaussian sampling in a single unit. This unit can encrypt and decrypt a block in 26.19 mu s and 16.80 mu s on a Virtex-6 LX75T FPGA, respectively - at moderate resource requirements of about 1506 slices and a few block RAMs. Additionally, we provide solutions for several practical issues with Ring-LWE encryption, including the reduction of ciphertext expansion, error rate and constant-time operation. We hope that this contribution helps to pave the way for the deployment of ideal lattice-based encryption in future real-world systems.\",\n \"Title: Lightweight code-based cryptography: QC-MDPC McEliece encryption on reconfigurable devices\\nYear: 2014\\n\\nAbstract: With the break of RSA and ECC cryptosystems in an era of quantum computing, asymmetric code-based cryptography is an established alternative that can be a potential replacement. A major drawback are large keys in the range between 50kByte to several MByte that prevented real-world applications of code-based cryptosystems so far. A recent proposal by Misoczki et al. showed that quasi-cyclic moderate density parity-check (QC-MDPC) codes can be used in McEliece encryption -- reducing the public key to just 0.6 kByte to achieve a 80-bit security level. Despite of reasonably small key sizes that could also enable small designs, previous work only report high-performance implementations with high resource consumptions of more than 13,000 slices on a large Xilinx Virtex-6 FPGA for a combined en-/decryption unit. In this work we focus on lightweight implementations of code-based cryptography and demonstrate that McEliece encryption using QC-MDPC codes can be implemented with a significantly smaller resource footprint -- still achieving reasonable performance sufficient for many applications, e.g., challenge-response protocols or hybrid firmware encryption. More precisely, our design requires just 68 slices for the encryption and around 150 slices for the decryption unit and is able to en-/decrypt an input block in 2.2ms and 13.4 ms, respectively.\",\n \"Title: Transforming write collisions in block RAMs into security applications\\nYear: 2009\\n\\nAbstract: Due to their versatile and generic structure, field programmable gate arrays (FPGA) allow dynamic reconfiguration of their logical resources just by loading configuration files. However, this flexibility also opens up the threat of theft of intellectual property (IP) since these configuration files can be easily extracted and cloned. In this context, the ability to bind a configuration to a specific device is an important step to prevent product counterfeiting. In this paper, we present a novel strategy to identify and authenticate FPGAs in applications using intrinsic, device-specific information (also known as physically unclonable functions). Our solution is based on the output of intentionally induced write collisions in synchronous dual-port block RAM (BRAM). We show that the output of such write collisions can be used to create unique device signatures. In addition to applications for chip identification and authentication, we also propose a solution to efficiently create secret keys on-chip. As a last contribution, we outline how to transform our idea into a circuit for true random number generation (TRNG).\",\n \"Title: Compact implementation and performance evaluation of hash functions in ATtiny devices\\nYear: 2012\\n\\nAbstract: The pervasive diffusion of electronic devices in security and privacy sensitive applications has boosted research in cryptography. In this context, the study of lightweight algorithms has been a very active direction over the last years. In general, symmetric cryptographic primitives are good candidates for low-cost implementations. For example, several previous works have investigated the performance of block ciphers on various platforms. Motivated by the recent SHA3 competition, this paper extends these studies to another family of cryptographic primitives, namely hash functions. We implemented different algorithms on an ATMEL AVR ATtiny45 8-bit microcontroller, and provide their performance evaluation. All the implementations were carried out with the goal of minimizing the code size and memory utilization, and are evaluated using a common interface. As part of our contribution, we make all the corresponding source codes available on a web page, under an open-source license. We hope that this paper provides a good basis for researchers and embedded system designers who need to include more and more functionalities in next generation smart devices.\",\n \"Title: Code-based cryptography on reconfigurable hardware: tweaking Niederreiter encryption for performance.\\nYear: 2013\\n\\nAbstract: Today’s public-key schemes that are either based on the factorization or the discrete logarithm problem. Since both problems are closely related, a major breakthrough in cryptanalysis (e.g., with the advent of quantum computing will render nearly all currently employed security system useless. Code-based public-key schemes rely on the alternative security assumption that decoding generic linear binary codes is NP-complete. Two code-based schemes for public-key encryption are available due to McEliece and Niederreiter. Although most researchers analyzed and implemented McEliece’s cryptosystem, we show in this work that the scheme by Niederreiter has some important advantages, such as smaller keys, more practical plain and ciphertext sizes and less computation complexity. In particular, we propose an efficient FPGA implementation of Niederreiter’s scheme that can encrypt more than 1.5 million plaintexts per seconds on a Xilinx Virtex-6 FPGA—outperforming all known implementations of other popular public-key cryptosystems so far.\",\n \"Title: An experimentally verified attack on full grain-128 using dedicated reconfigurable hardware\\nYear: 2011\\n\\nAbstract: In this paper we describe the first single-key attack which can recover the full key of the full version of Grain-128 for arbitrary keys by an algorithm which is significantly faster than exhaustive search (by a factor of about 238). It is based on a new version of a cube tester, which uses an improved choice of dynamic variables to eliminate the previously made assumption that ten particular key bits are zero. In addition, the new attack is much faster than the previous weak-key attack, and has a simpler key recovery process. Since it is extremely difficult to mathematically analyze the expected behavior of such attacks, we implemented it on RIVYERA, which is a new massively parallel reconfigurable hardware, and tested its main components for dozens of random keys. These tests experimentally verified the correctness and expected complexity of the attack, by finding a very significant bias in our new cube tester for about 7.5% of the keys we tested. This is the first time that the main components of a complex analytical attack are successfully realized against a full-size cipher with a special-purpose machine. Moreover, it is also the first attack that truly exploits the configurable nature of an FPGA-based cryptanalytical hardware.\",\n \"Title: Using Data Contention in Dual-ported Memories for Security Applications\\nYear: 2012\\n\\nAbstract: Field Programmable Gate Arrays (FPGA) provide the invaluable feature of dynamic hardware reconfiguration by loading configuration bit files. However, this flexibility also opens up the threat of theft of Intellectual Property (IP) since these configuration files can be easily extracted and cloned. In this context, the ability to bind an application configuration to a specific device is an important step to prevent product counterfeiting. Furthermore, such a technology can also enable advanced business models such as device-specific feature activation. In this work, we present a new technique to generate entropy on FPGA device--based on data contention in the hardware circuitry. For this entropy, we use the output of intentionally generated write collisions in synchronous dual-ported block RAMs (BRAM). We show that the parts of this output generated by such write collisions can be either probabilistic but also deterministic and device-specific. The characteristics of such an entropy source can be used for a large variety of security applications, such as chip identification and device authentication. In addition to that, we also propose a solution to efficiently create cryptographic keys on-chip at runtime. As a last contribution, we eventually present a strategy how to transform this entropy source into a circuit for True Random Number Generation (TRNG).\",\n \"Title: Reconfigurable trusted computing in hardware\\nYear: 2007\\n\\nAbstract: Trusted Computing (TC) is an emerging technology towards building trustworthy computing platforms. The TrustedComputing Group (TCG) has proposed several specifications to implement TC functionalities by extensions to common computing platforms, particularly the underlying hardware with a Trusted Platform Module (TPM). However, actual TPMs are mostly available for workstations and servers nowadays and rather for specific domainapplications and not primarily for embedded systems. Further, the TPM specifications are becoming monolithic andmore complex while the applications demand a scalable and flexible usage of TPM functionalities. In this paper we propose a reconfigurable (hardware) architecture with TC functionalities where we focus on TPMsas proposed by the TCG specifically designed for embedded platforms. Our approach allows for (i) an efficient andscalable design and update of TPM functionalities, in particular for hardware-based crypto engines and accelerators, (ii) establishing a minimal trusted computing base in hardware, (iii) including the TPM as well as its functionalities into the chain of trust that enables to bind sensitive data to the underlying reconfigurable hardware, and (iv) designing a manufacturer independent TPM. We discuss possible implementations based on current FPGAs and point out the associated challenges, in particular with respect to protection of the internal TPM state since it must not be subject to manipulation, replay, and cloning\",\n \"Title: Attacking atmel's cryptomemory EEPROM with special-purpose hardware\\nYear: 2013\\n\\nAbstract: Atmel's CryptoMemory devices are non-volatile memories with cryptographically secured access control. Recently, the authentication mechanism of these devices have been shown to be severely vulnerable. More precisely, to recover the secret key the published attack requires only two to six days of computation on a cluster involving 200 CPU cores. In this work, we identified and applied theoretical improvements to this attack and mapped it to a reconfigurable computing cluster, known as RIVYERA. Our solution provides significantly higher performance exceeding the previous implementation by a factor of 7.27, revealing the secret key obtained from the internal state in 0.55 days on average using only 30 authentication frames.\",\n \"Title: MicroEliece: McEliece for Embedded Devices\\nYear: 2009\\n\\nAbstract: Most advanced security systems rely on public-key schemes based either on the factorization or the discrete logarithm problem. Since both problems are known to be closely related, a major breakthrough in cryptanalysis tackling one of those problems could render a large set of cryptosystems completely useless. The McEliece public-key scheme is based on the alternative security assumption that decoding unknown linear binary codes is NP-complete. In this work, we investigate the efficient implementation of the McEliece scheme on embedded systems what was --- up to date --- considered a challenge due to the required storage of its large keys. To the best of our knowledge, this is the first time that the McEliece encryption scheme is implemented on a low-cost 8-bit AVR microprocessor and a Xilinx Spartan-3AN FPGA.\",\n \"Title: DSPs, BRAMs and a Pinch of Logic: New Recipes for AES on FPGAs\\nYear: 2008\\n\\nAbstract: We present an AES cipher implementation that is based on the BlockRAM and DSP units embedded within Xilinx's Virtex-5 FPGAs. An iterative \\\"basic\\\" module outputs a 32 bit column of an AES round each clock cycle, with a throughput of 1.76 Gbit/s when processing two 128 bit inputs. This construct is replicated four times for a 128 bit datapath for a full AES round with 6.21 Gbit/s throughput when processing eight inputs. Finally, the \\\"round\\\" module is replicated ten times for a fully unrolled design that yields over 55 Gbit/s of throughput. The combination and arrangement of the specialized embedded functions available in the FPGA allows us to implement our designs using very few traditional user logic elements such as flip-flops and lookup tables, yet still achieve these high throughputs. The complete source code for these designs is made publicly available for use in further research and for replicating our results. Our contribution ends with a discussion of comparing cipher implementations in the literature, and why these comparisons can be meaningless without a common reporting style, platform, or within the context of a specific constrained application.\",\n \"Title: Breaking Legacy Banking Standards with Special-Purpose Hardware\\nYear: 2008\\n\\nAbstract: In the field of eCommerce, online-banking is one of the major application requiring the usage of modern cryptography to protect the confidentiality and integrity of financial transactions between users and the banking system. In banking applications of some countries, the authorization of user transactions is performed with support of cryptographic One-Time-Password (OTP) tokens implementing ANSI X9.9-based challenge-response protocols.The legacy ANSI X9.9 standard is a DES-based authentication method on which we will demonstrate an attack based on a special-purpose hardware cluster. In this work we show how to break such an OTP-token with little effort in terms of costs and time. With an investment of about US $ 10,000 we are able to perform an attack which computes the key of a DES-based OTP token in less than a week having only three challenge-response pairs. Our attack can even be scaled linearly according to the budget of the attacker resulting in even faster breaking times. With this work, we want to point out once more that the immediate migration from legacy products using the DES algorithm is absolutely mandatory for security critical applications.\",\n \"Title: True random number generation in block memories of reconfigurable devices\\nYear: 2010\\n\\nAbstract: We present concepts and implementations to transform write collisions in memory blocks into an entropy source for random number generation. Write collisions in dual-ported block memories occur when both memory ports write simultaneously different data at the same memory location. After a thorough analysis of this effect, we present a robust methodology to generate digitized noise and randomness from such write collisions and also provide details how to implement post-processing methods for efficient bias and correlation removal. Finally, we present three concepts and implementations for random number generators stages that can deliver random data at an output rate of more than 100 MBit/s.\",\n \"Title: Side channels as building blocks.\\nYear: 2012\\n\\nAbstract: Since the introduction of the first side-channel analyses in academia about 15 years ago, several physical attacks have been presented that exploit side-channel leakages to break implementations of cryptographic algorithms. This article deals with the same physical property of electronic devices, but focuses on the art of tailoring it for constructive uses. More precisely, two scenarios, i.e., hardware Trojans and IP watermarking, are illustrated in which the designer of an electronic circuit can add functionality by considering side channels as part of the available design space. Both applications use the same concept, i.e., deliberately leaking a secret through a side channel while keeping the introduced side channel hidden from adversaries and attackers. This article provides a broad overview of the existing works for both applications and should serve as a comprehensible introduction to the underlying field of research. This includes many subtle details that have not been discussed in literature yet, including existing shortcomings and possible improvements to the existing works. The solutions summarized in this article provide general guidelines for theorists and practitioners to use side channels constructively to achieve designs that are robust against detection and removal. Furthermore, we present an entirely new design of a Trojan side-channel. This architecture demonstrates the potential of a Trojan side-channel that is neatly tailored to the targeted implementation. The new design removes all non-invasive starting points a third party could use to analyze or get access to the secret-channel.\",\n \"Title: Securely sealing Multi-FPGA systems\\nYear: 2012\\n\\nAbstract: The importance of hardware security of electronic systems is rapidly increasing due to (1) the increasing reliance of mass-produced and mission-critical systems on embedded electronics, and (2) the ever-growing supply chains that disentangle chip designers and manufacturers from OEMs. Our work shows how to dramatically reduce vulnerability to Trojan-horse injection and in-field component replacement. We propose methods to verify the authenticity and integrity of an FPGA configuration during startup and at runtime. We also developed efficient protocols for electronic sealing of a multi-FPGA system, which automatically enforces the system configuration detected upon power-up and bans further modifications.\",\n \"Title: The future of high-speed cryptography: new computing platforms and new ciphers\\nYear: 2011\\n\\nAbstract: Almost all of today's security systems rely on cryptographic primitives as core components which are usually considered the most trusted part of the system. The realization of these primitives on the underlying processing platform plays a crucial role for any real-world deployment. In this work, we discuss new trends in public-key cryptography that could potentially establish as alternatives to the currently used RSA and ECC cryptosystems. Analyzing these trends from a developer's perspective, we identify the requirements for optimal processing architectures. Moreover, we investigate if these requirements are already satisfied with latest processing platforms, i.e., which of the streaming, hybrid, multi-core or application-specific instructions processors provide a most promising target architecture.\",\n \"Title: New Protection Mechanisms for Intellectual Property in Reconfigurable Logic\\nYear: 2007\\n\\nAbstract: The distinct advantage of SRAM-based Field Programmable Gate Arrays (FPGA) is their flexibility for configuration changes. But this opens up the threat of Intellectual Property (IP) theft since the system configuration is stored in easy-to-access Flash memory. High-end FPGAs have already been extended with symmetric-key decryption engines used to load an encrypted version of the configuration that cannot simply be copied and used without knowledge of the secret key. However, with respect to business and licensing processes, this protection system lacks a convenient scheme for key transport and installation. We propose a new protection scheme for the IP of circuits in configuration bit files that provides a significant improvement to the current unsatisfying situation. It uses both public-key and symmetric cryptography, but does not burden FPGAs with the usual overhead of public-key cryptography: While it needs hard-wired symmetric cryptography, the public-key functionality is moved into a temporary configuration bit stream for a one-time setup procedure. This approach requires only very few modifications to current FPGA technology. Using five basic stages, the new protection scheme allows new accounting models for volume licensing of IP, with automated key installation on FPGAs taking place at the customer's site.\",\n \"Title: IPSecco: A lightweight and reconfigurable IPSec core\\nYear: 2012\\n\\nAbstract: In this paper we propose a reconfigurable lightweight Internet Protocol Security (IPSec) hardware core. Our architecture supports the main IPSec protocols; namely Authentication Header (AH), Encapsulating Security Payload (ESP), and Internet Key Exchange (IKE). In this work, the cryptographic algorithms and their modes of operation, which are at the heart of the IPSec protocols, are implemented in hardware. Instead of re-implementing common IPSec configurations, which are deemed “too heavy” for pervasive devices, we evaluate efficient implementations of standardized and/or well-known lightweight and hardware-friendly algorithms. In particular, we examine different versions of Present, Grøstl, Photon, and a very compact ECC core. As a consequence, we present IPSecco, a core with adequate security and only moderate resource requirements, making it suitable for lightweight devices. We selected the Xilinx Spartan family of Field Programmable Gate Arrays (FPGA) as target platform due its low-power footprint and reduced costs compared to other FPGAs. Our results show that it is possible to realize a high performance IPSec core even on members of the Spartan-3 family.\",\n \"Title: Towards efficient arithmetic for lattice-based cryptography on reconfigurable hardware\\nYear: 2012\\n\\nAbstract: In recent years lattice-based cryptography has emerged as quantum secure and theoretically elegant alternative to classical cryptographic schemes (like ECC or RSA). In addition to that, lattices are a versatile tool and play an important role in the development of efficient fully or somewhat homomorphic encryption (SHE/FHE) schemes. In practice, ideal lattices defined in the polynomial ring ℤp[x]/〈xn+1〉 allow the reduction of the generally very large key sizes of lattice constructions. Another advantage of ideal lattices is that polynomial multiplication is a basic operation that has, in theory, only quasi-linear time complexity of ${\\\\mathcal O}(n \\\\log{n})$ in ℤp[x]/〈xn+1〉. However, few is known about the practical performance of the FFT in this specific application domain and whether it is really an alternative. In this work we make a first step towards efficient FFT-based arithmetic for lattice-based cryptography and show that the FFT can be implemented efficiently on reconfigurable hardware. We give instantiations of recently proposed parameter sets for homomorphic and public-key encryption. In a generic setting we are able to multiply polynomials with up to 4096 coefficients and a 17-bit prime in less than 0.5 milliseconds. For a parameter set of a SHE scheme (n=1024,p=1061093377) our implementation performs 9063 polynomial multiplications per second on a mid-range Spartan-6.\",\n \"Title: Exploiting the Power of GPUs for Asymmetric Cryptography\\nYear: 2008\\n\\nAbstract: Modern Graphics Processing Units (GPU) have reached a dimension with respect to performance and gate count exceeding conventional Central Processing Units (CPU) by far. Many modern computer systems include --- beside a CPU --- such a powerful GPU which runs idle most of the time and might be used as cheap and instantly available co-processor for general purpose applications.In this contribution, we focus on the efficient realisation of the computationally expensive operations in asymmetric cryptosystems on such off-the-shelf GPUs. More precisely, we present improved and novel implementations employing GPUs as accelerator for RSA and DSA cryptosystems as well as for Elliptic Curve Cryptography (ECC). Using a recent Nvidia 8800GTS graphics card, we are able to compute 813 modular exponentiations per second for RSA or DSA-based systems with 1024 bit integers. Moreover, our design for ECC over the prime field P-224 even achieves the throughput of 1412 point multiplications per second.\",\n \"Title: Special-Purpose Hardware for Solving the Elliptic Curve Discrete Logarithm Problem\\nYear: 2008\\n\\nAbstract: The resistance against powerful index-calculus attacks makes Elliptic Curve Cryptosystems (ECC) an interesting alternative to conventional asymmetric cryptosystems, like RSA. Operands in ECC require significantly less bits at the same level of security, resulting in a higher computational efficiency compared to RSA. With growing computational capabilities and continuous technological improvements over the years, however, the question of the security of ECC against attacks based on special-purpose hardware arises. In this context, recently emerged low-cost FPGAs demand for attention in the domain of hardware-based cryptanalysis: the extraordinary efficiency of modern programmable hardware devices allow for a low-budget implementation of hardware-based ECC attacks---without the requirement of the expensive development of ASICs. With focus on the aspect of cost-efficiency, this contribution presents and analyzes an FPGA-based architecture of an attack against ECC over prime fields. A multi-processing hardware architecture for Pollard's Rho method is described. We provide results on actually used key lengths of ECC (128 bits and above) and estimate the expected runtime for a successful attack. As a first result, currently used elliptic curve cryptosystems with a security of 160 bit and above turn out to be infeasible to break with available computational and financial resources. However, some of the security standards proposed by the Standards for Efficient Cryptography Group (SECG) become subject to attacks based on low-cost FPGAs.\",\n \"Title: Generic side-channel countermeasures for reconfigurable devices\\nYear: 2011\\n\\nAbstract: In this work, we propose and evaluate generic hardware countermeasures against DPA attacks for recent FPGA devices. The proposed set of FPGA-specific countermeasures can be combined to resist a large variety of first-order DPA attacks, even with 100 million recorded power traces. This set includes generic and resource-efficient countermeasures for on-chip noise generation, random-data processing delays and S-box scrambling using dual-ported block memories. In particular, it is possible to build many of these countermeasures into a single IP-core or hard macro that then provides basic protection for any cryptographic implementation just by its inclusion in the design process - what is particularly useful for engineers with no or little background on security and side-channel attacks.\",\n \"Title: Two Ip Protection Schemes For Multi-Fpga Systems\\nYear: 2012\\n\\nAbstract: This paper proposes two novel protection schemes for multi-FPGA systems providing high security of IP designs licensed by IP vendors to system integrators and installed remotely in a hostile environment. In the first scheme, these useful properties are achieved by storing two different configuration keys inside an FPGA, while in the second scheme, they are obtained using a hardware white-box cipher for creating a trusted environment. Thanks to the proposed principles, FPGA configurations coming from different IP owners cannot be cloned or reverse-engineered by any involved party, including system integrator and other IP owners. The proposed schemes can be directly implemented in recent FPGAs such as Xilinx Spartan 6 and Virtex 6.\",\n \"Title: Software Speed Records For Lattice-Based Signatures\\nYear: 2013\\n\\nAbstract: Novel public-key cryptosystems beyond RSA and ECC are urgently required to ensure long-term security in the era of quantum computing. The most critical issue on the construction of such cryptosystems is to achieve security and practicability at the same time. Recently, lattice-based constructions were proposed that combine both properties, such as the lattice-based digital signature scheme presented at CHES 2012. In this work, we present a first highly-optimized SIMD-based software implementation of that signature scheme targeting Intel's Sandy Bridge and Ivy Bridge microarchitectures. This software computes a signature in only 634988 cycles on average on an Intel Core i5-3210M (Ivy Bridge) processor. Signature verification takes only 45036 cycles. This performance is achieved with full protection against timing attacks.\",\n \"Title: Establishing Chain of Trust in Reconfigurable Hardware\\nYear: 2007\\n\\nAbstract: Facing ubiquitous threats like computer viruses, trojans and theft of intellectual property, Trusted Computing (TC) is an emerging technology towards building trustworthy computing platforms. A recent initiative by the Trusted Computing Group (TCG) specifies the use of Trusted Platform Modules (TPM), currently implemented as dedicated, cost-effective crypto-chips mounted on the main board of computer systems. In this paper we propose implementations for TC functionalities based on more flexible and versatile approaches for reconfigurable and embedded architectures. Our approach allows for (i) a scalable design and update of TPM functionalities in embedded systems, (ii) the integration of the TPM hardware in the chain of trust to bind applications to the underlying TPM and the reconfigurable hardware, and (iii) the design of vendor independent TPMs.\",\n \"Title: Achieving side-channel protection with dynamic logic reconfiguration on modern FPGAs\\nYear: 2015\\n\\nAbstract: Reconfigurability is a unique feature of modern FPGA devices to load hardware circuits just on demand. This also implies that a completely different set of circuits might operate at the exact same location of the FPGA at different time slots, making it difficult for an external observer or attacker to predict what will happen at what time. In this work we present and evaluate a novel hardware implementation of the lightweight cipher PRESENT with built-in side-channel countermeasures based on dynamic logic reconfiguration. In our design we make use of Configurable Look-Up Tables (CFGLUT) integrated in modern Xilinx FPGAs to nearly instantaneously change hardware internals of our cipher implementation for improved resistance against side-channel attacks. We provide evidence from practical experiments based on a Spartan-6 platform that even with 10 million recorded power traces we were unable to detect a first-order leakage using the state-of-the-art leakage assessment.\",\n \"Title: Evaluating the Duplication of Dual-Rail Precharge Logics on FPGAs.\\nYear: 2015\\n\\nAbstract: Power-equalization schemes for digital circuits aim to harden cryptographic designs against power analysis attacks. With respect to dual-rail logics most of these schemes have originally been designed for ASIC platforms, but much efforts have been spent to map them to FPGAs as well. A particular challenge is here to apply those schemes to the predefined logic structures of FPGAs i.e., slices, LUTs, FFs, and routing switch boxes for which special tools are required. Due to the absence of such routing tools Yu and Schaumont presented the idea of duplicating i.e., dualizing a fully-placed-and-routed dual-rail precharge circuit with equivalent routing structures on an FPGA. They adopted such architecture from WDDL providing the Double WDDL DWDDL scheme. In this work we show that this general technique --- regardless of the underlying dual-rail logic --- is incapable to properly prevent side-channel leakages. Besides theoretical investigations on this issue we present practical evaluations on a Spartan-6 FPGA to demonstrate the flaws in such an approach. In detail, we consider an AES-128 encryption module realized by three dual-rail precharge logic styles as a case study and show that none of those schemes can provide the desired level of protection.\",\n \"Title: GliFreD: Glitch-Free Duplication - Towards Power-Equalized Circuits on FPGAs.\\nYear: 2018\\n\\nAbstract: Designers of secure hardware are required to harden their implementations against physical threats, such as power analysis attacks. In particular, cryptographic hardware circuits need to decorrelate their current consumption from the information inferred by processing (secret) data. A common technique to achieve this goal is the use of special logic styles that aim at equalizing the current consum...\",\n \"Title: High-Speed Signatures From Standard Lattices\\nYear: 2014\\n\\nAbstract: At CT-RSA 2014 Bai and Galbraith proposed a lattice-based signature scheme optimized for short signatures and with a security reduction to hard standard lattice problems. In this work we first refine the security analysis of the original work and propose a new 128-bit secure parameter set chosen for software efficiency. Moreover, we increase the acceptance probability of the signing algorithm through an improved rejection condition on the secret keys. Our software implementation targeting Intel CPUs with AVX/AVX2 and ARM CPUs with NEON vector instructions shows that even though we do not rely on ideal lattices, we are able to achieve high performance. For this we optimize the matrix-vector operations and several other aspects of the scheme and finally compare our work with the state of the art.\",\n \"Title: Towards Side-Channel Resistant Implementations Of Qc-Mdpc Mceliece Encryption On Constrained Devices\\nYear: 2014\\n\\nAbstract: Recent advances in code-based cryptography paved new ways for efficient asymmetric cryptosystems that combine decent performance with moderate key sizes. In this context, Misoczki et al. recently proposed the use of quasi-cyclic MDPC (QC-MDPC) codes for the McEliece cryptosystem. It was shown that these codes can provide both compact key representations and solid performance on high-end computing platforms. However, for widely used low-end microcontrollers only slow implementations for this promising construction have been presented so far.In this work we present an implementation of QC-MDPC McEliece encryption providing 80 bits of equivalent symmetric security on low-cost ARM Cortex-M4-based microcontrollers with a reasonable performance of 42 ms for encryption and 251-558 ms for decryption. Besides practical issues such as random error generation, we demonstrate side-channel attacks on a straightforward implementation of this scheme and finally propose timing-and instruction-invariant coding strategies and countermeasures to strengthen it against timing attacks as well as simple power analysis.\",\n \"Title: Enabling SRAM-PUFs on Xilinx FPGAs\\nYear: 2014\\n\\nAbstract: Physically Unclonable Functions (PUFs) based on the evaluation of uninitialized SRAM are one of the most promising PUF candidates to date. However, transferring their concept to Xilinx FPGAs is not straightforward since all SRAM-based block memories in these FPGAs are automatically cleared on power-up, destroying the desired initial bits of information. In this work we therefore propose a novel strategy to convert block memories of 28nm Xilinx FPGAs into SRAM-PUFs by exploiting their recently introduced feature of power-gating and partial reconfiguration.\",\n \"Title: THOR - The hardware onion router\\nYear: 2014\\n\\nAbstract: Security and privacy of data traversing internet have always been a major concern for all users. In this context, The Onion Routing (Tor) is the most successful protocol to anonymize global Internet traffic and is widely deployed as software on many personal computers or servers. In this paper, we explore the potential of modern reconfigurable devices to efficiently realize the Tor protocol on embedded devices. In particular, this targets the acceleration of the complex cryptographic operations involved in the handshake of routing nodes and the data stream encryption. Our hardware-based implementation on the Xilinx Zynq platform outperforms previous embedded solutions by more than a factor of 9 with respect to the cryptographic handshake - ultimately enabling quite inexpensive but highly efficient routers. Hence, we consider our work as a further milestone towards the development and the dissemination of low-cost and high performance onion relays that hopefully ultimately leads again to a more private Internet.\",\n \"Title: Area optimization of lightweight lattice-based encryption on reconfigurable hardware\\nYear: 2014\\n\\nAbstract: Ideal lattice-based cryptography gained significant attraction in the last years due to its versatility, simplicity and performance in implementations. Nevertheless, existing implementations of encryption schemes reported only results trimmed for high-performance what is certainly not sufficient for all applications in practice. To the contrary, in this work we investigate lightweight aspects and suitable parameter sets for Ring-LWE encryption and show optimizations that enable implementations even with very few resources on a reconfigurable hardware device. Despite of this restriction, we still achieve reasonable throughput that is sufficient for many today's and future applications.\",\n \"Title: Lattice-Based Signatures: Optimization and Implementation on Reconfigurable Hardware\\nYear: 2015\\n\\nAbstract: Nearly all of the currently used signature schemes, such as RSA or DSA, are based either on the factoring assumption or the presumed intractability of the discrete logarithm problem. As a consequence, the appearance of quantum computers or algorithmic advances on these problems may lead to the unpleasant situation that a large number of today’s schemes will most likely need to be replaced with more secure alternatives. In this work we present such an alternative—an efficient signature scheme whose security is derived from the hardness of lattice problems. It is based on recent theoretical advances in lattice-based cryptography and is highly optimized for practicability and use in embedded systems. The public and secret keys are roughly kB and kB long, while the signature size is approximately kB for a security level of around bits. We provide implementation results on reconfigurable hardware (Spartan/Virtex-6) and demonstrate that the scheme is scalable, has low area consumption, and even outperforms classical schemes.\",\n \"Title: Fault Sensitivity Analysis Meets Zero-Value Attack\\nYear: 2014\\n\\nAbstract: Previous works have shown that the combinatorial path delay of a cryptographic function, e.g., The AES S-box, depends on its input value. Since the relation between critical path delay and input value seems to be relatively random and highly dependent on the routing of the circuit, up to now only template or some collision attacks could reliably extract the used secret key of implementations not protected against fault attacks. Here we present a new attack which is based on the fact that, because of the zero-to-zero mapping of the AES Sbox inversion circuit, the critical path when processing the zero input is notably shorter than for all other inputs. Applying the attack to an AES design protected by an state-of-the-art fault detection scheme, we are able to fully recover the secret key in less than eight hours. Note that we neither require a known key measurement step (template case) nor a high similarity between different S-box instances (collision case). The only information gathered from the device is whether a fault occurred when processing a chosen plaintext.\",\n \"Title: Enhancing COPACOBANA for advanced applications in cryptography and cryptanalysis\\nYear: 2008\\n\\nAbstract: Cryptanalysis of symmetric and asymmetric ciphers is a challenging task due to the enormous amount of involved computations. To tackle this computa- tional complexity, usually the employment of special- purpose hardware is considered as best approach. We have built a massively parallel cluster system (COPA- COBANA) based on low-cost FPGAs as a cost-efficient platform primarily targeting cryptanalytical operations with these high computational efforts but low communi- cation and memory requirements. However, some par- allel applications in the field of cryptography are too complex for low-cost FPGAs and also require the avail- ability of at least moderate communication and memory facilities. Particularly, this holds true for arithmetic intensive application as well as ones with a highly com- plex data flow. In this contribution, we describe a novel architecture for a more versatile and reliable COPACOBANA ca- pable to host advanced cryptographic applications like high-performance digital signature generation accord- ing to the Elliptic Curve Digital Signature Algorithm (ECDSA) and integer factorization based on the Ellip- tic Curve Method (ECM). In addition to that, the new cluster design allows even to run more supercomputing applications beyond the field of cryptography.\",\n \"Title: Security analysis of index-based syndrome coding for PUF-based key generation\\nYear: 2015\\n\\nAbstract: Physical Unclonable Functions (PUFs) as secure providers for cryptographic keys have gained significant research interest in recent years. Since plain PUF responses are typically unreliable, error-correcting mechanisms are employed to transform a fuzzy PUF response into a deterministic cryptographic key. In this context, Index-Based Syndrome Coding (IBS) has been reported as being provably secure in case of identical and independently distributed PUF responses and is therefore an interesting option to implement a highly secure key provider. In this paper we analyze the security of IBS in combination with a k-sum PUF as proposed at CHES 2011. Since for a k-sum PUF the assumption of identical and independently distributed responses does not hold, the notion of leaked bits was introduced at CHES 2011 to capture the security of such constructions. Based on a refined analysis using hamming distance characterization and machine learning techniques, we show that the entropy of the key obtained is significantly lower than expected. More precisely, we obtained from our findings that even the construction from CHES with the highest security claims only achieves a bit entropy rate of 0.39.\",\n \"Title: Utilizing hard cores of modern FPGA devices for high-performance cryptography\\nYear: 2011\\n\\nAbstract: This article presents a unique design approach for the implementation of standardized symmetric and asymmetric cryptosystems\\n on modern FPGA devices. In contrast to many other FPGA implementations that algorithmically optimize the cryptosystems for\\n being optimally placed in the generic array logic, our primary implementation goal is to shift as many cryptographic operations\\n as possible into specific hard cores that have become available on many reconfigurable devices. For example, some of these\\n dedicated functions are designed to provide large blocks of memory or fast arithmetic functions for Digital Signal Processing\\n applications that can also be adopted for efficient cryptographic implementations. Based on these dedicated functions, we\\n present specific design approaches that enable a performance for the symmetric AES block cipher (FIPS 197) of up to 55 GBit/s\\n and a throughput of more than 30.000 scalar multiplications per second for asymmetric Elliptic Curve Cryptography over NIST’s\\n P-224 prime (FIPS 186-3).\",\n \"Title: Affine Equivalence and its Application to Tightening Threshold Implementations.\\nYear: 2015\\n\\nAbstract: Motivated by the development of Side-Channel Analysis SCA countermeasures which can provide security up﾿to a certain order, defeating higher-order attacks has become amongst the most challenging issues. For instance, Threshold Implementation TI which nicely solves the problem of glitches in masked hardware designs is able to avoid first-order leakages. Hence, its extension to higher orders aims at counteracting SCA attacks at higher orders, that might be limited to univariate scenarios. Although with respect to the number of traces as well as sensitivity to noise the higher the order, the harder it is to mount the attack, a d-order TI design is vulnerable to an attack at order $$d+1$$d+1. In this work we look at the feasibility of higher-order attacks on first-order TI from another perspective. Instead of increasing the order of resistance by employing higher-order TIs, we go toward introducing structured randomness into the implementation. Our construction, which is a combination of masking and hiding, is dedicated to TI designs and deals with the concept of \\\\\\\"affine equivalence\\\\\\\" of Boolean functions. Such a combination hardens a design practically against higher-order attacks so that these attacks cannot be successfully mounted. We show that the area overhead of our construction is paid off by its ability to avoid higher-order leakages to be practically exploitable.\",\n \"Title: Implementing Curve25519 for Side-Channel-Protected Elliptic Curve Cryptography.\\nYear: 2015\\n\\nAbstract: For security-critical embedded applications Elliptic Curve Cryptography (ECC) has become the predominant cryptographic system for efficient key agreement and digital signatures. However, ECC still involves complex modular arithmetic that is a particular burden for small processors. In this context, Bernstein proposed the highly efficient ECC instance Curve25519 that particularly enables efficient software implementations at a security level comparable to AES-128 with inherent resistance to simple power analysis (SPA) and timing attacks. In this work, we show that Curve25519 is likewise competitive on FPGAs even when countermeasures to thwart side-channel power analysis are included. Our basic multicore DSP-based architectures achieves a maximal performance of more than 32,000 point multiplications per second on a Xilinx Zynq 7020 FPGA. Including a mix of side-channel countermeasures to impede simple and differential power analysis, we still achieve more than 27,500 point multiplications per second with a moderate increase in logic resources.\",\n \"Title: Implementing QC-MDPC McEliece Encryption\\nYear: 2015\\n\\nAbstract: With respect to performance, asymmetric code-based cryptography based on binary Goppa codes has been reported as a highly interesting alternative to RSA and ECC. A major drawback is still the large keys in the range between 50 and 100KB that prevented real-world applications of code-based cryptosystems so far. A recent proposal by Misoczki et al. showed that quasi-cyclic moderate-density parity-check (QC-MDPC) codes can be used in McEliece encryption, reducing the public key to just 0.6KB to achieve an 80-bit security level. In this article, we provide optimized decoding techniques for MDPC codes and survey several efficient implementations of the QC-MDPC McEliece cryptosystem. This includes high-speed and lightweight architectures for reconfigurable hardware, efficient coding styles for ARM’s Cortex-M4 microcontroller, and novel high-performance software implementations that fully employ vector instructions. Finally, we conclude that McEliece encryption in combination with QC-MDPC codes not only enables high-performance implementations but also allows for lightweight designs on a wide range of different platforms.\",\n \"Title: Practical Lattice-Based Digital Signature Schemes\\nYear: 2015\\n\\nAbstract: Digital signatures are an important primitive for building secure systems and are used in most real-world security protocols. However, almost all popular signature schemes are either based on the factoring assumption (RSA) or the hardness of the discrete logarithm problem (DSA/ECDSA). In the case of classical cryptanalytic advances or progress on the development of quantum computers, the hardness of these closely related problems might be seriously weakened. A potential alternative approach is the construction of signature schemes based on the hardness of certain lattice problems that are assumed to be intractable by quantum computers. Due to significant research advancements in recent years, lattice-based schemes have now become practical and appear to be a very viable alternative to number-theoretic cryptography. In this article, we focus on recent developments and the current state of the art in lattice-based digital signatures and provide a comprehensive survey discussing signature schemes with respect to practicality. Additionally, we discuss future research areas that are essential for the continued development of lattice-based cryptography.\",\n \"Title: IND-CCA Secure Hybrid Encryption from QC-MDPC Niederreiter.\\nYear: 2016\\n\\nAbstract: QC-MDPC McEliece attracted significant attention as promising alternative public-key encryption scheme believed to be resistant against quantum computing attacks. Compared to binary Goppa codes, it achieves practical key sizes and was shown to perform well on constrained platforms such as embedded microcontrollers and FPGAs. However, so far none of the published QC-MDPC McEliece/Niederreiter implementations provide indistinguishability under chosen plaintext or chosen ciphertext attacks. Common ways for the McEliece and Niederreiter encryption schemes to achieve IND-CPA/IND-CCA security are surrounding constructions that convert them into secured schemes. In this work we take a slightly different approach presenting 1 an efficient implementation of QC-MDPC Niederreiter for ARM Cortex-M4 microcontrollers and 2 the first implementation of Persichetti's IND-CCA hybrid encryption scheme from PQCrypto'13 instantiated with QC-MDPC Niederreiter for key encapsulation and AES-CBC/AES-CMAC for data encapsulation. Both implementations achieve practical performance for embedded microcontrollers, at 80-bit security hybrid encryption takes 16.5ï¾źms, decryption 111ï¾źms and key-generation 386.4ï¾źms.\",\n \"Title: New ASIC/FPGA Cost Estimates for SHA-1 Collisions\\nYear: 2015\\n\\nAbstract: SHA-1 remains, till date, the most widely used hash function, in spite of several successful cryptanalytic attacks against it. These attacks, however, remain impractical due to high computation complexity and associated cost. We endeavor to do cost-time product estimation for an attack by the aid of application-specific hardware acceleration. This work proposes an Application-Specific Instruction-set Processor (ASIP), named Cracken. Cracken is aimed to efficiently realize near collision attack on SHA-1. The estimations of the physical attack complexity is done using 65nm standard CMOS technology and commercial FPGA devices. It is estimated, with post-layout simulations, that Stevens' differential attack with an estimated complexity of 2^57.5, can be executed in 46 days using 4096 Cracken cores at a cost of Euros 15m. Estimation for real collision with complexity 2^61 is also done. Our cost-time estimates reveal that an FPGA-based attack is more efficient compared to ASIC. Previously reported SHA-1 attacks based on ASIC and cloud computing platforms are also compiled and benchmarked for reference.\",\n \"Title: Bridging the Gap: Advanced Tools for Side-Channel Leakage Estimation beyond Gaussian Templates and Histograms.\\nYear: 2016\\n\\nAbstract: The accuracy and the fast convergence of a leakage model are both essential components for the efficiency of side-channel analysis. Thus for efficient leakage estimation an evaluator is requested to pick a Probability Density Function (PDF) that constitutes the optimal trade-off between both aspects. In the case of parametric estimation, Gaussian templates are a common choice due to their fast convergence, given that the actual leakages follow a Gaussian distribution (as in the case of an unprotected device). In contrast, histograms and kernel-based estimations are examples for non-parametric estimation that are capable to capture any distribution (even that of a protected device) at a slower convergence rate.\",\n \"Title: High-Performance and Lightweight Lattice-Based Public-Key Encryption.\\nYear: 2016\\n\\nAbstract: In the emerging Internet of Things, lightweight public-key cryptography is an essential component for many cost-efficient security solutions. Since conventional public-key schemes, such as ECC and RSA, remain expensive and energy hungry even after aggressive optimization, this work investigates a possible alternative. In particular, we show the practical potential of replacing the Gaussian noise distribution in the Ring-LWE based encryption scheme by Lindner and Peikert/Lyubashevsky et al. with a binary distribution. When parameters are carefully chosen, our construction is resistant against any state-of-the-art cryptanalytic techniques (e.g., attacks on original Ring-LWE or NTRU) and suitable for low-cost scenarios. In the end, our scheme can enable public-key encryption even on very small and low-cost 8-bit (ATXmega128) and 32-bit (Cortex-M0) microcontrollers.\",\n \"Title: Secure architectures of future emerging cryptography SAFEcrypto.\\nYear: 2016\\n\\nAbstract: Funded under the European Union's Horizon 2020 research and innovation programme, SAFEcrypto will provide a new generation of practical, robust and physically secure post-quantum cryptographic solutions that ensure long-term security for future ICT systems, services and applications. The project will focus on the remarkably versatile field of Lattice-based cryptography as the source of computational hardness, and will deliver optimised public key security primitives for digital signatures and authentication, as well identity based encryption (IBE) and attribute based encryption (ABE). This will involve algorithmic and design optimisations, and implementations of lattice-based cryptographic schemes addressing cost, energy consumption, performance and physical robustness. As the National Institute of Standards and Technology (NIST) prepares for the transition to a post-quantum cryptographic suite B, urging organisations that build systems and infrastructures that require long-term security to consider this transition in architectural designs; the SAFEcrypto project will provide Proof-of-concept demonstrators of schemes for three practical real-world case studies with long-term security requirements, in the application areas of satellite communications, network security and cloud. The goal is to affirm Lattice-based cryptography as an effective replacement for traditional number-theoretic public-key cryptography, by demonstrating that it can address the needs of resource-constrained embedded applications, such as mobile and battery-operated devices, and of real-time high performance applications for cloud and network management infrastructures.\",\n \"Title: Information reconciliation schemes in physical-layer security: A survey.\\nYear: 2016\\n\\nAbstract: Information reconciliation is an essential part of physical-layer based key agreement. It enables the equalization of similar, but disagreeing channel observations of respective communicating parties. Due to a broad variety of underlying mathematical constructions and a large parameter space, there is a lack of systematic classification of the individual schemes. To address this issue, we present an extensive survey of existing protocols. Furthermore, we derive a generalized layer model for information reconciliation, show how existing approaches map to this model and how it supports future research work in this field.\",\n \"Title: Sixth International Workshop on Trustworthy Embedded Devices (TrustED 2016).\\nYear: 2016\\n\\nAbstract: The Internet of Things (IoT) is expected to become a global information and communication infrastructure for cyber physical systems and to bring numerous value-added services for modern society. However, the integration of heterogeneous devices and service models into a cohesive system significantly increases the complexity of design and deployment and introduces the new challenges for the security of systems and processed as well as the privacy of the collected data. The Workshop on Trustworthy Embedded Devices (TrustED) addresses all aspects of security and privacy related to embedded systems and the IoT. TrustED 2016 is a continuation of previous workshops in this series, which were held in conjunction with ESORICS 2011, IEEE Security & Privacy 2012, ACM CCS 2013, ACM CCS 2014, and ACM CCS 2015 (see http://www.trusted-workshop.de for details). The goal of this workshop is to bring together experts from academia and research institutes, industry, and government in the field of security and privacy in cyber physical systems to discuss and investigate the problems, challenges, and recent scientific and technological developments.\",\n \"Title: On the Energy Cost of Channel Based Key Agreement.\\nYear: 2016\\n\\nAbstract: Besides security, energy consumption is a major concern for devices in the Internet of Things (IoT). We compare the energy consumption of two key agreement schemes -- Channel-Based Key Agreement (CBKA) and Elliptic Curve Diffie-Hellman (ECDH) -- in the IoT setting, using Wi-Fi as wireless communication interface. While ECDH is a well-studied protocol, CBKA has received attention only in recent years. Several publications proposed CBKA as a low-energy alternative to ECDH, but they did not address the energy cost of communication. For a fair comparison, we implemented the schemes on a 32-bit ARM Cortex M3-based IoT platform and measured the respective energy consumption for computation and communication. Our results show that the limiting factor for CBKA over Wi-Fi is the energy cost of communication, in particular the cost of acquiring the Received Signal Strength Indicator (RSSI) values. Even in an optimal scenario, CBKA must not measure more than ca. 300 RSSI values to be more energy efficient than ECDH. This is at most 1/5 of RSSI values required by CBKA implementations reported in the literature. As an optimization, we present a refined CBKA protocol which can save up to 25% of the energy compared to existing protocols by exploiting inherent data exchanges for entropy extraction.\",\n \"Title: Practical CCA2-Secure and Masked Ring-LWE Implementation.\\nYear: 2018\\n\\nAbstract: During the last years public-key encryption schemes based on the hardness of ring-LWE have gained significant popularity. For real-world security applications assuming strong adversary models, a number of practical issues still need to be addressed. In this work we thus present an instance of ring-LWE encryption that is protected against active attacks (i.e., adaptive chosen-ciphertext attacks) and equipped with countermeasures against side-channel analysis. Our solution is based on a postquantum variant of the Fujisaki-Okamoto (FO) transform combined with provably secure first-order masking. To protect the key and message during decryption, we developed a masked binomial sampler that secures the re-encryption process required by FO. Our work shows that CCA2-secured RLWE-based encryption can be achieved with reasonable performance on constrained devices but also stresses that the required transformation and handling of decryption errors implies a performance overhead that has been overlooked by the community so far. With parameters providing 233 bits of quantum security, our implementation requires 4,176,684 cycles for encryption and 25,640,380 cycles for decryption with masking and hiding countermeasures on a Cortex-M4F. The first-order security of our masked implementation is also practically verified using the non-specific t-test evaluation methodology.\",\n \"Title: Hiding Higher-Order Side-Channel Leakage - Randomizing Cryptographic Implementations in Reconfigurable Hardware.\\nYear: 2017\\n\\nAbstract: First-order secure Threshold Implementations (TI) of symmetric cryptosystems provide provable security at a moderate overhead; yet attacks using higher-order statistical moments are still feasible. Cryptographic instances compliant to Higher-Order Threshold Implementation (HO-TI) can prevent such attacks, however, usually at unacceptable implementation costs. As an alternative concept we investigate in this work the idea of dynamic hardware modification, i.e., random changes and transformations of cryptographic implementations in order to render higher-order attacks on first-order TI impractical. In a first step, we present a generic methodology which can be applied to (almost) every cryptographic implementation. In order to investigate the effectiveness of our proposed strategy, we use an instantiation of our methodology that adapts ideas from White-Box Cryptography and applies this construction to a first-order secure TI. Further, we show that dynamically updating cryptographic implementations during operation provides the ability to avoid higher-order leakages to be practically exploitable.\",\n \"Title: A grain in the silicon: SCA-protected AES in less than 30 slices\\nYear: 2016\\n\\nAbstract: AES is the predominant block cipher used worldwide in many cryptographic applications. Despite of the wealth of already available implementations, we here introduce an ultra-lightweight AES-128 implementation specifically tailored for reconfigurable hardware. Our basic proposal presents a full AES-128 providing 9.12 Mbit/s throughput and occupying just 21 slices of a Spartan-6 and no additional memories. We also show that this architecture almost, inherently supports shuffling as side-channel countermeasure and provide results of a practical evaluation. Our protected design fits into 24 slices providing 7.82 Mbit/s throughput. Finally, we present a complete AES core that combines previous results with random number generation which fits 28 slices at 4.35 Mbit/s throughput.\",\n \"Title: Secure and Private, yet Lightweight, Authentication for the IoT via PUF and CBKA.\\nYear: 2016\\n\\nAbstract: The Internet of Things IoT is boon and bane. It offers great potential for new business models and ecosystems, but raises major security and privacy concerns. Because many IoT systems collect, process, and store personal data, a secure and privacy-preserving identity management is of utmost significance. Yet, strong resource limitations of IoT devices render resource-hungry public-key cryptography infeasible. Additionally, the security model of IoT enforces solutions to work under memory-leakage attacks. Existing constructions address either the privacy issue or the lightweightness, but not both. Our work contributes towards bridging this gap by combining physically unclonable functions PUFs and channel-based key agreement CBKA: i We show a flaw in a PUF-based authentication protocol, when outsider chosen perturbation security cannot be guaranteed. ii We present a solution to this flaw by introducing CBKA with an improved definition. iii We propose a provably secure and lightweight authentication protocol by combining PUFs and CBKA.\",\n \"Title: Strong 8-bit Sboxes with efficient masking in hardware extended version.\\nYear: 2017\\n\\nAbstract: Block ciphers are arguably the most important cryptographic primitive in practice. While their security against mathematical attacks is rather well understood, physical threats such as side-channel analysis (SCA) still pose a major challenge for their security. An effective countermeasure to thwart SCA is using a cipher representation that applies the threshold implementation (TI) concept. However, there are hardly any results available on how this concept can be adopted for block ciphers with large (i.e., 8-bit) Sboxes. In this work we provide a systematic analysis on and search for 8-bit Sbox constructions that can intrinsically feature the TI concept, while still providing high resistance against cryptanalysis. Our study includes investigations on Sboxes constructed from smaller ones using Feistel, SPN, or MISTY network structures. As a result, we present a set of new Sboxes that not only provide strong cryptographic criteria, but are also optimized for TI. We believe that our results will find an inspiring basis for further research on high-security block ciphers that intrinsically feature protection against physical attacks.\",\n \"Title: Cryptography for Next Generation TLS: Implementing the RFC 7748 Elliptic Curve448 Cryptosystem in Hardware.\\nYear: 2017\\n\\nAbstract: With RFC 7748 the two elliptic curves Curve25519 and Curve448 were proposed for the next generation of TLS. Both curves were designed and optimized purely for software implementation; their implementation in hardware or physical protection against side-channel attacks were not considered in the design phase. Recently, it has been shown that for Curve25519 an efficient implementations in hardware along with side-channel protection is feasible -- yet results for the high-security Curve448 are missing. In this work we demonstrate that Curve448 can indeed be efficiently and securely implemented in hardware. We present a novel architecture for Curve448 that can compute more than 1000 point multiplications per second with 1580 logic slices and 33 DSP units of a Xilinx XC7Z020 FPGA.\",\n \"Title: Lattice-based cryptography: From reconfigurable hardware to ASIC\\nYear: 2016\\n\\nAbstract: As progress in technology is predicted to make quantum computers available in the next few decades, it is imperative to design public-key cryptosystems capable of resisting attacks that are perceived to be possible using these new platforms. Lattice-based cryptography is one of the most promising quantum-safe candidates being considered to replace current public-key systems. Thus, it has been extensively evaluated in terms of both hardware and software implementations. However, to date lattice-based hardware designs have only been proposed for reconfigurable FPGA devices, leaving ASIC designs unexplored. In this paper, we present and discuss the main challenges and opportunities in implementing lattice-based algorithms on dedicated ASIC devices.\",\n \"Title: ParTI: Towards Combined Hardware Countermeasures against Side-Channeland Fault-Injection Attacks\\nYear: 2016\\n\\nAbstract: Side-channel analysis and fault-injection attacks are known as major threats to any cryptographic implementation. Hardening cryptographic implementations with appropriate countermeasures is thus essential before they are deployed in the wild. However, countermeasures for both threats are of completely different nature: Side-channel analysis is mitigated by techniques that hide or mask key-dependent information while resistance against fault-injection attacks can be achieved by redundancy in the computation for immediate error detection. Since already the integration of any single countermeasure in cryptographic hardware comes with significant costs in terms of performance and area, a combination of multiple countermeasures is expensive and often associated with undesired side effects. In this work, we introduce a countermeasure for cryptographic hardware implementations that combines the concept of a provably-secure masking scheme i.e., threshold implementation with an error detecting approach against fault injection. As a case study, we apply our generic construction to the lightweight LED cipher. Our LED instance achieves first-order resistance against side-channel attacks combined with a fault detection capability that is superior to that of simple duplication for most error distributions at an increased area demand of 12﾿%.\",\n \"Title: High-Performance Ideal Lattice-Based Cryptography on 8-Bit AVR Microcontrollers\\nYear: 2017\\n\\nAbstract: Over recent years lattice-based cryptography has received much attention due to versatile average-case problems like Ring-LWE or Ring-SIS that appear to be intractable by quantum computers. In this work, we evaluate and compare implementations of Ring-LWE encryption and the bimodal lattice signature scheme (BLISS) on an 8-bit Atmel ATxmega128 microcontroller. Our implementation of Ring-LWE encryption provides comprehensive protection against timing side-channels and takes 24.9ms for encryption and 6.7ms for decryption. To compute a BLISS signature, our software takes 317ms and 86ms for verification. These results underline the feasibility of lattice-based cryptography on constrained devices.\",\n \"Title: Confident Leakage Assessment - A Side-Channel Evaluation Framework Based On Confidence Intervals\\nYear: 2018\\n\\nAbstract: Cryptographic devices that potentially operate in hostile physical environments need to be secured against side channel attacks. In order to ensure the effectiveness of the required countermeasures, scientists, developers, and evaluators need efficient methods to test the security level of a device. In this paper we propose a new framework based on confidence intervals that extends established t-test based approaches for test vector leakage assessment (TVLA). In comparison to previous TVLA approaches the new methodology does not only enable the detection of leakage but can also assert its absence. The framework is robust against noise in the evaluation system and thereby avoids false negatives. These improvements can be achieved without overhead in measurement complexity and with a minimum of additional computational costs compared to previous approaches.We evaluate our method under realistic conditions by applying it to a protected implementation of AES.\",\n \"Title: Physical Protection of Lattice-Based Cryptography: Challenges and Solutions.\\nYear: 2018\\n\\nAbstract: The impending realization of scalable quantum computers will have a significant impact on today's security infrastructure. With the advent of powerful quantum computers public key cryptographic schemes will become vulnerable to Shor's quantum algorithm, undermining the security current communications systems. Post-quantum (or quantum-resistant) cryptography is an active research area, endeavoring to develop novel and quantum resistant public key cryptography. Amongst the various classes of quantum-resistant cryptography schemes, lattice-based cryptography is emerging as one of the most viable options. Its efficient implementation on software and on commodity hardware has already been shown to compete and even excel the performance of current classical security public-key schemes. This work discusses the next step in terms of their practical deployment, i.e., addressing the physical security of lattice-based cryptographic implementations. We survey the state-of-the-art in terms of side channel attacks (SCA), both invasive and passive attacks, and proposed countermeasures. Although the weaknesses exposed have led to countermeasures for these schemes, the cost, practicality and effectiveness of these on multiple implementation platforms, however, remains under-studied.\",\n \"Title: Exploring RFC 7748 for Hardware Implementation: Curve25519 and Curve448 with Side-Channel Protection\\nYear: 2018\\n\\nAbstract: Recent revelations on manipulations and back-doors in modern ECC have initiated the revision of existing schemes and led to the selection of two new solutions for next-generation TLS proposed in RFC 7748: Curve25519 and Curve448. Unfortunately, both curves were designed and optimized primarily for software implementations; their implementation in hardware and physical protection against SCA has been neglected during the design phase. In this work, we demonstrate that both curves can indeed be efficiently and securely mapped to hardware structures of modern FPGAs while including advanced protection mechanisms against physical attacks and still providing high performance and throughput. In particular, our Curve25519 architecture provides more than 1 700 point multiplications per second, using only 1 006 logic slices (LSs) and 20 digital signal processors (DSPs) of a mid-range Xilinx XC7Z020 FPGA. Furthermore, our Curve448 architecture still achieves more than 600 operations per second at a significantly higher security level of 224 bits, using not more than 1 985 LSs and 33 DSPs on the same device. In addition, we performed a practical, test-based leakage assessment for both architectures. More precisely, we investigated the detection of scalar- and base-point-dependable leakage individually while our designs were incorporated scalar blinding and point randomization countermeasures. Eventually, our findings prove with high confidence, that we cannot detect any scalar- and base-point-dependable leakage even after evaluating 1 000 000 power measurements.\",\n \"Title: Profiled Power Analysis Attacks Using Convolutional Neural Networks with Domain Knowledge.\\nYear: 2018\\n\\nAbstract: Evaluation of cryptographic implementations against profiled side-channel attacks plays a fundamental role in security testing nowadays. Recently, deep neural networks and especially Convolutional Neural Networks have been introduced as a new tool for that purpose. Although having several practical advantages over common Gaussian templates such as intrinsic feature extraction, the deep-learning-based profiling techniques proposed in literature still require a suitable leakage model for the implementation under test. Since this is a crucial task, we are introducing domain knowledge to exploit the full power of approximating very complex functions with neural networks. By doing so, we are able to attack the secret key directly without any assumption about the leakage behavior. Our experiments confirmed that our method is much more efficient than state-of-the-art profiling approaches when targeting an unprotected hardware and a protected software implementation of the AES.\",\n \"Title: Evaluation of Lattice-Based Signature Schemes in Embedded Systems\\nYear: 2018\\n\\nAbstract: Lattice-based cryptography is a promising candidate and remedy in public-key cryptography in case quantum computers become feasible or a major breakthrough in solving the factorization problem or the discrete logarithm problem is achieved. Due to ongoing research in this field, many schemes still lack implementations that examine their practicability, especially for embedded systems. In this work we discuss the potential of lattice-based signature schemes for practical applications on constrained devices in a post-quantum era. We focus on the schemes GLP, BLISS, and Dilithium and discuss their unique properties as well as challenges regarding their implementation on embedded devices. In this regard we present and review optimized implementations of these schemes for ARM Cortex-M4 microcontrollers to evaluate the practical performance of the schemes.\",\n \"Title: Practical lattice-based cryptography: a signature scheme for embedded systems\\nYear: 2012\\n\\nAbstract: Nearly all of the currently used and well-tested signature schemes (e.g. RSA or DSA) are based either on the factoring assumption or the presumed intractability of the discrete logarithm problem. Further algorithmic advances on these problems may lead to the unpleasant situation that a large number of schemes have to be replaced with alternatives. In this work we present such an alternative --- a signature scheme whose security is derived from the hardness of lattice problems. It is based on recent theoretical advances in lattice-based cryptography and is highly optimized for practicability and use in embedded systems. The public and secret keys are roughly 12000 and 2000 bits long, while the signature size is approximately 9000 bits for a security level of around 100 bits. The implementation results on reconfigurable hardware (Spartan/Virtex 6) are very promising and show that the scheme is scalable, has low area consumption, and even outperforms some classical schemes.\",\n \"Title: Compact implementation and performance evaluation of block ciphers in ATtiny devices\\nYear: 2012\\n\\nAbstract: The design of lightweight block ciphers has been a very active research topic over the last years. However, the lack of comparative source codes generally makes it hard to evaluate the extent to which implementations of different ciphers actually reach their low-cost goals on various platforms. This paper reports on an initiative aiming to relax this issue. First, we provide implementations of 12 block ciphers on an ATMEL AVR ATtiny45 8-bit microcontroller, and make the corresponding source code available on a web page. All implementations are made public under an open-source license. Common interfaces and design goals are followed by all designers to achieve comparable implementation results. Second, we evaluate performance figures of our implementations with respect to different metrics, including energy-consumption measurements and show our improvements compared to existing implementations.\",\n \"Title: Standard Lattice-Based Key Encapsulation on Embedded Devices.\\nYear: 2018\\n\\nAbstract: Lattice-based cryptography is one of the most promising candidates being considered to replace current public-key systems in the era of quantum computing. In 2016, Bos et al. proposed the key exchange scheme FrodoCCS, that is also a submission to the NIST post-quantum standardization process, modified as a key encapsulation mechanism (FrodoKEM). The security of the scheme is based on standard lattices and the learning with errors problem. Due to the large parameters, standard latticebased schemes have long been considered impractical on embedded devices. The FrodoKEM proposal actually comes with parameters that bring standard lattice-based cryptography within reach of being feasible on constrained devices. In this work, we take the final step of efficiently implementing the scheme on a low-cost FPGA and microcontroller devices and thus making conservative post-quantum cryptography practical on small devices. Our FPGA implementation of the decapsulation (the computationally most expensive operation) needs 7,220 look-up tables (LUTs), 3,549 flip-flops (FFs), a single DSP, and only 16 block RAM modules. The maximum clock frequency is 162 MHz and it takes 20.7 ms for the execution of the decapsulation. Our microcontroller implementation has a 66% reduced peak stack usage in comparison to the reference implementation and needs 266 ms for key pair generation, 284 ms for encapsulation, and 286 ms for decapsulation. Our results contribute to the practical evaluation of a post-quantum standardization candidate.\",\n \"Title: Applications of machine learning techniques in side-channel attacks: a survey\\nYear: 2020\\n\\nAbstract: With increasing expansion of the Internet of Things, embedded devices equipped with cryptographic modules become an important factor to protect sensitive data. Even though the employed algorithms in such devices are mathematically secure in theory, adversaries may still be able to compromise them by means of side-channel attacks. In power-based side-channel attacks, the instantaneous power consumption of the target is analyzed with statistical tools to draw conclusions about the secret keys that are used. There is a recent line of work that additionally makes use of techniques from the machine learning domain to attack cryptographic implementations. Since a complete review of this emerging field has not been done so far, this research aims to survey the current state of the art. We use a target-based classification to differentiate published work and drive general conclusions according to a common machine learning workflow. Furthermore, we outline the relationship between traditional power analysis techniques and machine learning-based attacks. This enables researchers to gain a better understanding of the topic in order to design new attack methods as well as potential countermeasures.\",\n \"Title: Securing Cryptographic Circuits by Exploiting Implementation Diversity and Partial Reconfiguration on FPGAs\\nYear: 2019\\n\\nAbstract: Adaptive and reconfigurable systems such as Field Programmable Gate Arrays (FPGAs) play an integral part of many complex embedded platforms. This implies the capability to perform runtime changes to hardware circuits on demand. In this work, we make use of this feature to propose a no-vel countermeasure against physical attacks of cryptographic implementations. In particular, we leverage exploration of the implementation space on FPGAs to create various circuits with different hardware layouts from a single design of the Advanced Encryption Standard (AES), that are dynamically exchanged during device operation. We provide evidence from practical experiments based on a modern Xilinx ZYNQ UltraScale+ FPGA that our approach increases the resistance against physical attacks by at least factor two. Furthermore, the genericness of our approach allows an easy adaption to other algorithms and combination with other countermeasures.\",\n \"Title: Efficiently Masking Binomial Sampling at Arbitrary Orders for Lattice-Based Crypto\\nYear: 2019\\n\\nAbstract: With the rising popularity of lattice-based cryptography, the Learning with Errors (LWE) problem has emerged as a fundamental core of numerous encryption and key exchange schemes. Many LWE-based schemes have in common that they require sampling from a discrete Gaussian distribution which comes with a number of challenges for the practical instantiation of those schemes. One of these is the inclusion of countermeasures against a physical side-channel adversary. While several works discuss the protection of samplers against timing leaks, only few publications explore resistance against other side-channels, e.g., power. The most recent example of a protected binomial sampler (as used in key encapsulation mechanisms to sufficiently approximate Gaussian distributions) from CHES 2018 is restricted to a first-order adversary and cannot be easily extended to higher protection orders.\",\n \"Title: Write Me and I'll Tell You Secrets - Write-After-Write Effects On Intel CPUs.\\nYear: 2022\\n\\nAbstract: There is a long history of side channels in the memory hierarchy of modern CPUs. Especially the cache side channel is widely used in the context of transient execution attacks and covert channels. Therefore, many secure cache architectures have been proposed. Most of these architectures aim to make the construction of eviction sets infeasible by randomizing the address-to-cache mapping. In this paper, we investigate the peculiarities of write instructions in recent CPUs. We identify Write+Write, a new side channel on Intel CPUs that leaks whether two addresses contend for the same cache set. We show how Write+Write can be used for rapid construction of eviction sets on current cache architectures. Moreover, we replicate the Write+Write effect in gem5 and demonstrate on the example of ScatterCache how it can be exploited to efficiently attack state-of-the-art cache randomization schemes. In addition to the Write+Write side channel, we show how Write-After-Write effects can be leveraged to efficiently synchronize covert channel communication across CPU cores. This yields the potential for much more stealthy covert channel communication than before.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":83,"string":"83"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":256,"string":"256"}}},{"rowIdx":257,"cells":{"question_id":{"kind":"string","value":"Ye Zhao"},"question":{"kind":"string","value":"Generate an abstract for the title \"Detail-preserving compression for smoke-based flow visualization\" using the following items: Smoke, flows, visualization, compression, details"},"answer":{"kind":"string","value":"Smoke is a useful method to visualize flows from scientific experiments or physical simulations in many applications of science, engineering, graphics, and virtual reality. In visualizing flows, smoke evolution inside a flow field creates 3D, high-resolution, and time-varying data sets. The large data size imposes challenge on storing and transmitting the smoke animation results where good compression techniques are demanded. Furthermore, small-scale smoke details play important roles in visualizing and conveying realistic flow behavior. They should be well preserved in compression and reconstructed to create smooth animation effect in decompression. This requirement impairs the direct adaptation of existing techniques in video and volume compression. In this paper, we design new techniques to enable effective smoke visualization compression with smooth detail preservation. The motion estimation between key frames of density fields is implemented by a special bidirectional advection. The intermediate frames are built from advected key frames with specific blending. The advection is driven by motion vectors over nonuniform blocks, which are created with an adaptive simplification of velocity field to reflect the heterogeneous velocity variations. Moreover, pertinent intra-frame compression techniques are integrated. Our approach eventually achieves good compression performance and quality with easy control."},"correct_answer":{"kind":"string","value":"Smoke is a useful method to visualize flows from scientific experiments or physical simulations in many applications of science, engineering, graphics, and virtual reality. In visualizing flows, smoke evolution inside a flow field creates 3D, high-resolution, and time-varying data sets. The large data size imposes challenge on storing and transmitting the smoke animation results where good compression techniques are demanded. Furthermore, small-scale smoke details play important roles in visualizing and conveying realistic flow behavior. They should be well preserved in compression and reconstructed to create smooth animation effect in decompression. This requirement impairs the direct adaptation of existing techniques in video and volume compression. In this paper, we design new techniques to enable effective smoke visualization compression with smooth detail preservation. The motion estimation between key frames of density fields is implemented by a special bidirectional advection. The intermediate frames are built from advected key frames with specific blending. The advection is driven by motion vectors over nonuniform blocks, which are created with an adaptive simplification of velocity field to reflect the heterogeneous velocity variations. Moreover, pertinent intra-frame compression techniques are integrated. Our approach eventually achieves good compression performance and quality with easy control."},"documents":{"kind":"list like","value":["Title: Spectral Image Decolorization\nYear: 2010\n\nAbstract: We propose a novel method for decolorizing a color image to grayscale, which preserves the chromatic contrast to be lost if\n using a simple luminance mapping. Unlike previous work, the conversion performs in spectral domain after applying Fourier\n transforms on luminance and chromatic channels, and the resultant intensity is recovered from an inverse transform. Frequency\n spectra inherently provide the magnitude of changes (i.e. contrast) among the channels, in all spatial scales. Consequently,\n only simple arithmetic operations are needed to add chromatic differences to the final grayscale intensity, leading to realtime\n computational speed. Moreover, users can flexibly control the decolorization effects by interactively adjusting visually-intuitive\n parameters, in addition to our predefined values. The method has great potential to be incorporated in commercial software\n and printer drivers due to its simplicity, speed and repeatability.","Title: Voxels on Fire\nYear: 2003\n\nAbstract: We introduce a method for the animation of fire propagation and the burning consumption of objects represented as volumetric data sets. Our method uses a volumetric fire propagation model based on an enhanced distance field. It can simulate the spreading of multiple fire fronts over a specified isosurface without actually having to create that isosurface. The distance field is generated from a specific shell volume that rapidly creates narrow spatial bands around the virtual surface of any given isovalue. The complete distance field is then obtained by propagation from the initial bands. At each step multiple fire fronts can evolve simultaneously on the volumetric object. The flames of the fire are constructed from streams of particles whose movement is regulated by a velocity field generated with the hardware-accelerated Lattice Boltzmann Model (LBM). The LBM provides a physically-based simulation of the air flow around the burning object. The object voxels and the splats associated with the flame particles are rendered in the same pipeline so that the volume data with its external and internal structures can be displayed along with the fire.","Title: Discrete construction of order-k voronoi diagram\nYear: 2010\n\nAbstract: The order-k Voronoi diagrams are difficult to construct because of their complicated structures. In traditional algorithm, production process was extremely complex. While discrete algorithm is only concerned with positions of generators, so it is effective for constructing Voronoi diagrams with complicated shapes of Voronoi polygons. It can be applied to order- k Voronoi diagram with any generators, and can get over most shortcomings of traditional algorithm. So it is more useful and effective. Model is constructed with discrete algorithm. And the application example shows that the algorithm is both simple and useful, and it is of high potential value in practice.","Title: Discrete construction of power network voronoi diagram\nYear: 2011\n\nAbstract: Power Network Voronoi diagrams are difficult to construct when the position relation of road segments are complicated. In traditional algorithm, The distance between objects must be calculated by selecting the minimum distance to their shared borders and doubling this value. When road segments cross or coincide with each other, production process will be extremely complex because we have to consider separately these parts. In this paper, we use discrete construction of network Voronoi diagrams. The algorithm can get over all kinds of shortcomings that we have just mentioned. So it is more useful and effective than the traditional ones. We also construct model according the algorithm. And the application example shows that the algorithm is both simple and useful, and it is of high potential value in practice.","Title: Enhancing fluid animation with adaptive, controllable and intermittent turbulence\nYear: 2010\n\nAbstract: This paper proposes a new scheme for enhancing fluid animation with controllable turbulence. An existing fluid simulation from ordinary fluid solvers is fluctuated by turbulent variation modeled as a random process of forcing. The variation is precomputed as a sequence of solenoidal noise vector fields directly in the spectral domain, which is fast and easy to implement. The spectral generation enables flexible vortex scale and spectrum control following a user prescribed energy spectrum, e.g. Kolmogorov's cascade theory, so that the fields provide fluctuations in subgrid scales and/or in preferred large octaves. The vector fields are employed as turbulence forces to agitate the existing flow, where they act as a stimulus of turbulence inside the framework of the Navier-Stokes equations, leading to natural integration and temporal consistency. The scheme also facilitates adaptive turbulent enhancement steered by various physical or user-defined properties, such as strain rate, vorticity, distance to objects and scalar density, in critical local regions. Furthermore, an important feature of turbulent fluid, intermittency is created by applying turbulence control during randomly selected temporal periods.","Title: Incorporating stochastic turbulence in particle-based fluid simulation\nYear: 2012\n\nAbstract: We propose a new fluid modeling technique aimed at incorporating stochastic turbulence into a widely used Lagrangian fluid solver, the Smoothed Particle Hydrodynamics (SPH) method. We add to each SPH particle a swirling probability to model its likelihood to act as a swirling incentive particle (SIP). Particles are selected as a SIP randomly based on the probability, and a SIP spins its neighboring particles to rotate around itself by applying rotational force. The force is computed from a swirling vorticity of the SIP. We model the production, development, and spreading of the swirling probability and vorticity among all SPH particles. The algorithm inherently implements preferred turbulence evolution including vortex aggregation and decay. The turbulent effects are non-repeating and easily controlled by animators. Our method is fully integrated with the SPH scheme with minimal extra memory usage, computational load, and programming efforts.","Title: Discrete construction of Voronoi diagrams for cross generators\nYear: 2010\n\nAbstract: Voronoi diagrams for cross generators are difficult to construct because of their complicated position relation. In traditional algorithm, when generators cross or coincide with each other, production process will be extremely complex because we have to consider separately these parts. In this paper, we use discrete construction of Voronoi diagrams. The algorithm can get over all kinds of shortcomings that we have just mentioned. So it is more useful and effective than the traditional ones. We also construct model according the algorithm. And the application example shows that the algorithm is both simple and useful, and it is of high potential value in practice.","Title: Dispersion simulation and visualization for urban security\nYear: 2004\n\nAbstract: We present a system for simulating and visualizing the propagation of dispersive contaminants with an application to urban security. In particular, we simulate airborne contaminant propagation in open environments characterised by sky-scrapers and deep urban canyons. Our approach is based on the multiple relaxation time lattice Boltzmann model (MRTLBM), which can efficiently handle complex boundary conditions such as buildings. In addition, we model thermal effects on the flow field using the hybrid thermal MRTLBM. Our approach can also accommodate readings from various sensors distributed in the environment and adapt the simulation accordingly. We accelerate the computation and efficiently render many buildings with small textures on the GPU. We render streamlines and the contaminant smoke with self-shadowing composited with the textured buildings.","Title: Real-time visualization of streaming text with a force-based dynamic system.\nYear: 2012\n\nAbstract: Streamit lets users explore visualizations of text streams without prior knowledge of the data. It incorporates incoming documents from a continuous source into an existing visualization context with automatic grouping and separation based on document similarities. A powerful user interface allows in-depth data analysis.","Title: Visualizing clusters in parallel coordinates for visual knowledge discovery\nYear: 2012\n\nAbstract: Parallel coordinates is frequently used to visualize multi-dimensional data. In this paper, we are interested in how to effectively visualize clusters of multi-dimensional data in parallel coordinates for the purpose of facilitating knowledge discovery. In particular, we would like to efficiently find a good order of coordinates for different emphases on visual knowledge discovery. To solve this problem, we link it to the metric-space Hamiltonian path problem by defining the cost between every pair of coordinates as the number of inter-cluster or intra-cluster crossings. This definition connects to various efficient solutions and leads to very fast algorithms. In addition, to better observe cluster interactions, we also propose to shape clusters smoothly by an energy reduction model which provides both macro and micro view of clusters.","Title: Robust stability criterion for discrete-time uncertain Markovian jumping neural networks with defective statistics of modes transitions.\nYear: 2011\n\nAbstract: This brief is concerned with the robust stability problem for a class of discrete-time uncertain Markovian jumping neural networks with defective statistics of modes transitions. The parameter uncertainties are considered to be norm-bounded, and the stochastic perturbations are described in terms of Brownian motion. Defective statistics means that the transition probabilities of the multimode neural networks are not exactly known, as assumed usually. The scenario is more practical, and such defective transition probabilities comprise three types: known, uncertain, and unknown. By invoking the property of the transition probability matrix and the convexity of uncertain domains, a sufficient stability criterion for the underlying system is derived. Furthermore, a monotonicity is observed concerning the maximum value of a given scalar, which bounds the stochastic perturbation that the system can tolerate as the level of the defectiveness varies. Numerical examples are given to verify the effectiveness of the developed results.","Title: GPU accelerated lattice Boltzmann simulation for rotational turbulence\nYear: 2014\n\nAbstract: In this work, we numerically study decaying isotropic turbulence in periodic cubes with frame rotation using the lattice Boltzmann method (LBM) and present the results of rotation effects on turbulence. The implementation of LBM is on a GPU (Graphic Processing Unit) platform using CUDA (Compute Unified Device Architecture). Through the accelerated GPU-LBM simulation, we look into various effects of frame rotation on turbulence. It has been observed that rotation slows down the decay of kinetic energy and enstrophy. Rotation also breaks isotropy and induces vortex tubes in the direction of frame rotation. Characteristics related to velocity and its derivatives have been studied with and without rotation. Without rotation, the kinetic energy and enstrophy decay follow -10/7 and -17/7 scaling respectively whereas in the presence of rotation with the relatively small Rossby number (large rotation intensity), the energy decay slows down to -5/21 scaling when the initial isotropic turbulence energy spectrum is scaled to k^4. These scalings with and without rotation are in quantitative agreements with the predictions from Kolmogorov hypotheses respectively. The skewness and kurtosis are seen more fluctuating in rotational turbulence, which agrees with the results from NS-based computation. Using this accelerated and validated GPU-LBM computation tool, we are further studying the inverse energy transfer behavior with and without rotation aiming to quantify the effects of rotation on the inverse energy transfer to reveal underlying physics of a particular stage of the turbulence development. The results will be presented in near future.","Title: Gpu-Accelerated Surface Denoising And Morphing With Lattice Boltzmann Scheme\nYear: 2008\n\nAbstract: In this paper, we introduce a parallel numerical scheme, the lattice Boltzmann method, to shape modeling applications. The motivation of using this originally-designed fluid dynamics solver in surface modeling is its simplicity, locality, parallelism from the cellular-automata-originated updating rules, which can directly be mapped onto modem graphics hardware. A surface is implicitly represented by the signed distance field. The distances are then used in a modified LBM scheme as its computing primitive, instead of the densities in traditional LBM. The scheme can simulate curvature motions to smooth the surface with a diffusion process. Furthermore, an initial value level set method can be implemented for surface morphing. The distance difference between a morphing surface and a target surface defines the speed function of the evolving level sets, and is used as the driving force in the LBM. Our GPU-accelerated LBM algorithm has achieved outstanding performance for the denoising and morphing examples. It has the great potential to be further applied as a general GPU computing framework to many other solid and shape modeling applications.","Title: Spatial Density Voronoi Diagram And Construction\nYear: 2012\n\nAbstract: To fill a theory gap of Voronoi diagrams that there have been no reports of extended diagrams in spatial density so far. A new concept of spatial density Voronoi diagram was proposed. An important property was presented and proven. And a construction algorithm was presented. Spatial density can be used to indicate factors related to density such as conveyance and the traffic conditions. Some properties of spatial density Voronoi diagram were also introduced. In accordance with discrete construction method, achieved the construction of spatial density Voronoi diagram. Spatial density Voronoi diagram is a developed Voronoi diagram, and planar ordinary Voronoi diagram can be regarded as its special cases. It both perfected the theory about Voronoi diagrams, and extended the range of applications of Voronoi diagrams.","Title: Melting and flowing in multiphase environment\nYear: 2006\n\nAbstract: This paper presents a method to simulate the melting and flowing phenomena with different materials in multiple phases. In such a multiphase environment, solid objects are melted because of heating and the melted liquid flows while interacting with the ambient air flow. Our simulation is based on a modified lattice Boltzmann method (LBM), where the fluid dynamics of the air flow and the melted liquid is modeled within a common lattice framework. Therefore, no particular front tracking methods are required for the liquid–air interface. The liquid–solid and air–solid interfaces are implemented as curved boundaries in the LBM, which can accommodate arbitrarily shaped solid objects. Heat transfer is incorporated with a finite difference discretization of a standard diffusion–advection equation simulating the temperature evolution. The temperature and body forces (gravity and surface tension) are easily applied by adopting a new version of the LBM: multiple-relaxation-time LBM (MRTLBM). The melting and flowing behavior is controlled by the heat source, the viscosity and the body forces. All the numerical computations in our method are local and parallelizable, therefore, interactive speed is achieved by hardware acceleration on the contemporary graphics hardware (GPU).","Title: Lattice Boltzmann based PDE solver on the GPU\nYear: 2008\n\nAbstract: In this paper, we propose a hardware-accelerated PDE (partial differential equation) solver based on the lattice Boltzmann model (LBM). The LBM is initially designed to solve fluid dynamics by constructing simplified microscopic kinetic models. As an explicit numerical scheme with only local operations, it has the advantage of being easy to implement and especially suitable for graphics hardware (GPU) acceleration. Beyond the Navier–Stokes equation of fluid mechanics, a typical LBM can be modified to solve the parabolic diffusion equation, which is further used to solve the elliptic Laplace and Poisson equations with a diffusion process. These PDEs are widely used in modeling and manipulating images, surfaces and volumetric data sets. Therefore, the LBM scheme can be used as an GPU-based numerical solver to provide a fast and convenient alternative to traditional implicit iterative solvers. We apply this method to several examples in volume smoothing, surface fairing and image editing, achieving outstanding performance on contemporary graphics hardware. It has the great potential to be used as a general GPU computing framework for efficiently solving PDEs in image processing, computer graphics and visualization.","Title: Visual simulation of thermal fluid dynamics in a pressurized water reactor\nYear: 2009\n\nAbstract: We present a simulation and visualization system for a critical application—analysis of the thermal fluid dynamics inside a pressurized water reactor of a nuclear power plant when cold water is injected into the reactor vessel. We employ a hybrid thermal lattice Boltzmann method (HTLBM), which has the advantages of ease of parallelization and ease of handling complex simulation boundaries. For efficient computation and storage of the irregular-shaped simulation domain, we classify the domain into nonempty and empty cells and apply a novel packing technique to organize the nonempty cells. This method is implemented on a GPU cluster for acceleration. We demonstrate the formation of cold-water plumes in the reactor vessel. A set of interactive visualization tools, such as side-view slices, 3D volume rendering, thermal layers rendering, and panorama rendering, are provided to collectively visualize the structure and dynamics of the temperature field in the vessel. To the best of our knowledge, this is the first system that combines 3D simulation and visualization for analyzing thermal shock risk in a pressurized water reactor.","Title: Pattern-guided smoke animation with lagrangian coherent structure\nYear: 2011\n\nAbstract: Fluid animation practitioners face great challenges from the complexity of flow dynamics and the high cost of numerical simulation. A major hindrance is the uncertainty of fluid behavior after simulation resolution increases and extra turbulent effects are added. In this paper, we propose to regulate fluid animations with predesigned flow patterns. Animators can design their desired fluid behavior with fast, low-cost simulations. Flow patterns are then extracted from the results by the Lagrangian Coherent Structure (LCS) that represents major flow skeleton. Therefore, the final high-quality animation is confined towards the designed behavior by applying the patterns to drive high-resolution and turbulent simulations. The pattern regulation is easily computed and achieves controllable variance in the output. The method makes it easy to design special fluid effects, which increases the usability and scalability of various advanced fluid modeling technologies.","Title: Image matching by fast random sample consensus\nYear: 2013\n\nAbstract: The traditional Random Sample Consensus (RANSAC) algorithm tends to exhibit deficiencies when faced with large amounts of data. In this paper, we present an algorithm called fast Random Sample Consensus (abbr. F-RANSAC) which is able to improve computation efficiency and robustness. We first use the nearest neighbor algorithm to retrieve candidate match points with ranked matching scores. We then construct representative data sets by using a minimal number of optimal matches. Finally, the target homographic matrix is fitted based on the representative data set. Experiments on affine covariant region datasets demonstrate that F-RANSAC significantly enhances computation efficiency(3 times to 10 times) and slightly improves accuracy.","Title: Active Suspension Control With Frequency Band Constraints and Actuator Input Delay\nYear: 2012\n\nAbstract: This paper investigates the problem of vehicle active suspension control with frequency band constraints and actuator input delay. First, the mathematical model of suspension systems is established, and the problem of suspension control with finite-frequency constraints is formulated to match the characteristics of the human body. Then, the finite-frequency method is developed to deal with the problem of suspension control with actuator input delay, based on the generalized Kalman-Yakubovich-Popov lemma. Compared with the traditional entire-frequency approach for active suspension systems, the finite-frequency approach proposed in this paper achieves better disturbance attenuation performance for the chosen frequency range while the constraints required by real situation are guaranteed in the controller design. The effectiveness and merits of the proposed method are verified by a number of simulations with several types of road disturbances.","Title: DYNATOPS: a dynamic topic-based publish/subscribe architecture\nYear: 2013\n\nAbstract: Emerging societal scale notification applications call for a system that is able to efficiently support simple, yet changing subscriptions for a very large number of users. In this paper we propose DYNATOPS, a dynamic topic-based pub/sub architecture that provides efficient scalable societal scale event notifications for dynamic subscriptions via distributed broker networks. In DYNATOPS, users are moderately repositioned on brokers and brokers are moderately repositioned on the overlay structure for efficient event notifications, to adapt to the publications and subscription dynamics. In contrast to existing self-organized techniques, the broker network reconfiguration in DYNATOPS is executed in a planned manner utilizing a cost-driven reconfiguration process. With extensive experiments, we observe that under highly dynamic subscriptions DYNATOPS can still maintain an efficient dissemination structure that provides 30% less notification delay and overhead in general, and a reconfiguration cost reduction of 80% as compared to other state-of-the-art systems.","Title: GSFord: Towards a Reliable Geo-social Notification System\nYear: 2012\n\nAbstract: The eventual goal of any notification system is to deliver appropriate messages to all relevant recipients with very high reliability in a timely manner. In particular, we focus on notification in extreme situations (e.g. disasters) where geographically correlated failures hinder the ability to reach recipients inside the corresponding failed region. In this paper, we present GSFord, a reliable geo-social notification system that is aware of (a) the geographies in which the message needs to be disseminated and (b) the social network characteristics of the intended recipient, in order to maximize/increase the coverage and reliability. GSFord builds robust geo-aware P2P overlays to provide efficient location-based message delivery and reliable storage of geo-social information of recipients. When an event occurs, GSFord is able to efficiently deliver the message to recipients who are either (a) located in the event area or (b) socially correlated to the event (e.g. relatives/friends of those who are impacted by an event). Furthermore, GSFord leverages the geo-social information to trigger a social diffusion process, which operates through out-of band channels such as phone calls and human contacts, in order to reach recipients which are isolated in the failed region. Through extensive evaluations, we show that GSFord is reliable, the social diffusion process enhanced by GSFord reaches up to 99.9% of desired recipients even under massive geographically correlated regional failures. We also show that GSFord is efficient even under skewed distribution of user populations.","Title: Modeling path duration time in dynamic convergecast network\nYear: 2013\n\nAbstract: Estimating communication latency is challenging in dynamic settings, e.g mobile applications where the source and/or destination of the communication can move arbitrarily. In this paper, we explore a many-to-one communication pattern, called convergecast, where mobile sensors report their sensed values to one or more servers (data sinks) in a periodic or queried manner. Such ”convergecast” communication is becoming increasingly relevant in sensor monitoring and pervasive sensing applications. An important aspect of enabling accurate collection is to ensure small delays in the collection process. The path duration, i.e time between when a path from sensor to source is established and when it gets disrupted, is a key factor that affects end-to-end delay; much of the existing work on this topic is in the context of MANETs. We propose and evaluate a probabilistic model in convergecast to capture path duration times given models of the network/transmission, the scale of the network and mobility of network elements. We validate our model through simulations and verify that the proposed model can provide a reasonable representation for end-to-end delays in the convergecast network. Pervasive sensor networks of the future are likely to encompass multiple access technologies with varying network properties and transmission characteristics. The ability to model end-to-end network properties (such as path duration) can assist in improved utilization in such pervasive multinetworks.","Title: Visual simulation of heat shimmering and mirage.\nYear: 2007\n\nAbstract: We provide a physically-based framework for simulating the natural phenomena related to heat interaction between objects and the surrounding air. We introduce a heat transfer model between the heat source objects and the ambient flow environment, which includes conduction, convection, and radiation. The heat distribution of the objects is represented by a novel temperature texture. We simulate the thermal flow dynamics that models the air flow interacting with the heat by a hybrid thermal lattice Boltzmann model (HTLBM). The computational approach couples a multiple-relaxation-time LBM (MRTLBM) with a finite difference discretization of a standard advection-diffusion equation for temperature. In heat shimmering and mirage, the changes in the index of refraction of the surrounding air are attributed to temperature variation. A nonlinear ray tracing method is used for rendering. Interactive performance is achieved by accelerating the computation of both the MRTLBM and the heat transfer, as well as the rendering on contemporary graphics hardware (GPU).","Title: Optimum location on fuzzy clustering method\nYear: 2010\n\nAbstract: In this paper, fuzzy cluster method is presented to solve traditional optimum location problem. We consider objects of users as some discrete points. Points are classified by using fuzzy clustering method on condition of large number of them, because the distance between points can be tested by the similarity of axis of the given points. We discuss the single-objective location problem, and construct a model according to realistic situation. The method can also be used in the multi-objective location problem.","Title: Lattice-based flow field modeling.\nYear: 2004\n\nAbstract: We present an approach for simulating the natural dynamics that emerge from the interaction between a flow field and immersed objects. We model the flow field using the Lattice Boltzmann Model (LBM) with boundary conditions appropriate for moving objects and accelerate the computation on commodity graphics hardware (GPU) to achieve real-time performance. The boundary conditions mediate the exchange of momentum between the flow field and the moving objects resulting in forces exerted by the flow on the objects as well as the back-coupling on the flow. We demonstrate our approach using soap bubbles and a feather. The soap bubbles illustrate Fresnel reflection, reveal the dynamics of the unseen flow field in which they travel, and display spherical harmonics in their undulations. Our simulation allows the user to directly interact with the flow field to influence the dynamics in real time. The free feather flutters and gyrates in response to lift and drag forces created by its motion relative to the flow. Vortices are created as the free feather falls in an otherwise quiescent flow.","Title: PIWI: visually exploring graphs based on their community structure.\nYear: 2013\n\nAbstract: Community structure is an important characteristic of many real networks, which shows high concentrations of edges within special groups of vertices and low concentrations between these groups. Community related graph analysis, such as discovering relationships among communities, identifying attribute-structure relationships, and selecting a large number of vertices with desired structural features and attributes, are common tasks in knowledge discovery in such networks. The clutter and the lack of interactivity often hinder efforts to apply traditional graph visualization techniques in these tasks. In this paper, we propose PIWI, a novel graph visual analytics approach to these tasks. Instead of using Node-Link Diagrams (NLDs), PIWI provides coordinated, uncluttered visualizations, and novel interactions based on graph community structure. The novel features, applicability, and limitations of this new technique have been discussed in detail. A set of case studies and preliminary user studies have been conducted with real graphs containing thousands of vertices, which provide supportive evidence about the usefulness of PIWI in community related tasks.","Title: Stochastic modeling of light-weight floating objects\nYear: 2011\n\nAbstract: Light-weight objects floating inside a flow play a significant role in the liveliness of our world (e.g., leaves, dust, snowflakes, bubbles). They follow the flow and show complex and chaotic motion. First, animators usually add simple random noise to the streaming path. However, this method yields low-quality floating behavior since the random noise does not take into account the spatial and temporal distribution of underlying flow turbulence. For example, obstacle-induced oscillation cannot be easily created as a major source of the unique motion. Second, floating objects can be passively advected by flow velocities from physically-based simulation. A critical challenge is that modeling the important jiggling motion requires turbulent flow field, which is hard to achieve by direct numerical simulation (DNS) due to limited computational resources and numerical dissipation. This situation deteriorates severely when realtime performance and interactivity are demanded in a 3D gaming environment. Moreover, the floating motion has intrinsic stochastic nature, i.e., the repeated executions result in nonidentical dynamics, which is not achievable with deterministic simulation. Third, adding noise to fluid solvers can introduce chaotic flow velocities (e.g. [Pfaff et al. 2010]). In an approach, special Langevin particles affect fluid solver with forces [Chen et al. 2011]. However, such methods rely on DNS and apply chaotic addition to the whole fluid domain, which is inefficient in handling a group of floating objects inside.","Title: Flow simulation with locally-refined LBM\nYear: 2007\n\nAbstract: We simulate 3D fluid flow by a locally-refined lattice Boltzmann method (LBM) on graphics hardware. A low resolution LBM simulation running on a coarse grid models global flow behavior of the entire domain with low consumption of computational resources. For regions of interest where small visual details are desired, LBM simulations are performed on fine grids, which are separate grids superposed on the coarse one. The flow properties on boundaries of the fine grids are determined by the global simulation on the coarse grid. Thus, the locally refined fine-grid simulations follow the global fluid behavior, and model the desired small-scale and turbulent flow motion with their denser numerical discretization. A fine grid can be initiated and terminated at any time while the global simulation is running. It can also move inside the domain with a moving object to capture small-scale vortices caused by the object. Besides the performance improvement due to the adaptive simulation, the locally-refined LBM is suitable for acceleration on contemporary graphics hardware (GPU), since it involves only local and linear computations. Therefore, our approach achieves fast and adaptive 3D flow simulation for computer games and other interactive applications.","Title: Line–Line Fault Analysis and Protection Challenges in Solar Photovoltaic Arrays\nYear: 2013\n\nAbstract: Fault analysis in solar photovoltaic (PV) arrays is a fundamental task to protect PV modules from damage and to eliminate risks of safety hazards. This paper focuses on line-line faults in PV arrays that may be caused by short-circuit faults or double ground faults. The effect on fault current from a maximum-power-point tracking of a PV inverter is discussed and shown to, at times, prevent overcurrent protection devices (OCPDs) to operate properly. Furthermore, fault behavior of PV arrays is highly related to the fault location, fault impedance, irradiance level, and use of blocking diodes. Particularly, this paper examines the challenges to OCPD in a PV array brought by unique faults: One is a fault that occurs under low-irradiance conditions, and the other is a fault that occurs at night and evolves during “night-to-day” transition. In both circumstances, the faults might remain hidden in the PV system, no matter how irradiance changes afterward. These unique faults may subsequently lead to unexpected safety hazards, reduced system efficiency, and reduced reliability. A small-scale experimental PV system has been developed to further validate the conclusions.","Title: Parallel 3D Image Segmentation of Large Data Sets on a GPU Cluster\nYear: 2009\n\nAbstract: In this paper, we propose an inherent parallel scheme for 3D image segmentation of large volume data on a GPU cluster. This method originates from an extended Lattice Boltzmann Model (LBM), and provides a new numerical solution for solving the level set equation. As a local, explicit and parallel scheme, our method lends itself to several favorable features: (1) Very easy to implement with the core program only requiring a few lines of code; (2) Implicit computation of curvatures; (3) Flexible control of generating smooth segmentation results; (4) Strong amenability to parallel computing, especially on low-cost, powerful graphics hardware (GPU). The parallel computational scheme is well suited for cluster computing, leading to a good solution for segmenting very large data sets.","Title: Tile-Based Parallel Coordinates And Its Application In Financial Visualization\nYear: 2010\n\nAbstract: Parallel coordinates technique has been widely used in information visualization applications and it has achieved great success in visualizing multivariate data and perceiving their trends. Nevertheless, visual clutter usually weakens or even diminishes its ability when the data size increases. In this paper, we first propose a tile-based parallel coordinates, where the plotting area is divided into rectangular tiles. Each tile stores an intersection density that counts the total number of polylines intersecting with that tile. Consequently, the intersection density is mapped to optical attributes, such as color and opacity, by interactive transfer functions. The method visualizes the polylines efficiently and informatively in accordance with the density distribution, and thus, reduces visual cluttering and promotes knowledge discovery. The interactivity of our method allows the user to instantaneously manipulate the tiles distribution and the transfer functions. Specifically, the classic parallel coordinates rendering is a special case of our method when each tile represents only one pixel. A case study on a real world data set, U. S. stock mutual fund data of year 2006, is presented to show the capability of our method in visually analyzing financial data. The presented visual analysis is conducted by an expert in the domain of finance. Our method gains the support from professionals in the finance field, they embrace it as a potential investment analysis tool for mutual fund managers, financial planners, and investors.","Title: A visual analytics approach to exploring protein flexibility subspaces\nYear: 2013\n\nAbstract: Understanding what causes proteins to change shape and how the resulting shape influences function will expedite the design of more narrowly focused drugs and therapies. Shape alterations are often the result of flexibility changes in a set of localized neighborhoods that may or may not act in concert. Computational models have been developed to predict flexibility changes under varying empirical parameters. In this paper, we tackle a significant challenge facing scientists when analyzing outputs of a computational model, namely how to identify, examine, compare, and group interesting neighborhoods of proteins under different parameter sets. This is a difficult task since comparisons over protein subunits that comprise diverse neighborhoods are often too complex to characterize with a simple metric and too numerous to analyze manually. Here, we present a series of novel visual analytics approaches toward addressing this task. User scenarios illustrate the utility of these approaches and feedback from domain experts confirms their effectiveness.","Title: Langevin Particle: A Self-Adaptive Lagrangian Primitive for Flow Simulation Enhancement\nYear: 2011\n\nAbstract: We develop a new Lagrangian primitive, named Langevin particle, to incorporate turbulent flow details in fluid simulation. A group of the particles are distributed inside the simulation domain based on a turbulence energy model with turbulence viscosity. A particle in particular moves obeying the generalized Langevin equation, a well known stochastic differential equation that describes the particle's motion as a random Markov process. The resultant particle trajectory shows self-adapted fluctuation in accordance to the turbulence energy, while following the global flow dynamics. We then feed back Langevin forces to the simulation based on the stochastic trajectory, which drive the flow with necessary turbulence. The new hybrid flow simulation method features nonrestricted particle evolution requiring minimal extra manipulation after initiation. The flow turbulence is easily controlled and the total computational overhead of enhancement is minimal based on typical fluid solvers.","Title: Using Entropy-Related Measures in Categorical Data Visualization.\nYear: 2014\n\nAbstract: A wide variety of real-world applications generate massive high dimensional categorical datasets. These datasets contain categorical variables whose values comprise a set of discrete categories. Visually exploring these datasets for insights is of great interest and importance. However, their discrete nature often confounds the direct application of existing multidimensional visualization techniques. We use measures of entropy, mutual information, and joint entropy as a means of harnessing this discreteness to generate more effective visualizations. We conduct user studies to assess the benefits in visual knowledge discovery.","Title: Asynchronous Filtering of Discrete-Time Switched Linear Systems With Average Dwell Time\nYear: 2011\n\nAbstract: Switched dynamical systems can be found in many practical electronic circuits, such as various kinds of power converters, chaos generators, etc. This paper is concerned with the filter design problem for a class of switched system with average dwell time switching. Mode-dependent full-order filters are designed taking a more practical phenomenon, the asynchronous switching into account, where “asynchronous” means that the switching of the filters to be designed has a lag to the switching of the system modes. New results on the stability and l2-gain analyses for the systems are first given where the Lyapunov-like functions during the running time of subsystems are allowed to increase. In light of the proposed Lyapunov-like functions, the desired mode-dependent filters can be designed in that the unmatched filters are allowed to perform in the interval of the asynchronous switching before the matched ones are applied. In H∞ sense, the problem of asynchronous filtering for the underlying systems in linear cases is formulated and the conditions of the existence of admissible asynchronous filters are obtained. Two examples are provided to show the potential of the developed results.","Title: Visual Analysis of Mutual Fund Performance\nYear: 2009\n\nAbstract: Mutual funds are probably the most important investment instruments for investors. Their performance is mainly affected by their characteristics, such as asset size, turnover and fee structure. It is thus of the investors' highest priorities to understand the relation between fund performance and these properties. Typically, financial researchers use the linear regression technique to statistically assess the relation from massive fund performance data. Unfortunately, the prevailing methods may be confounded by the existence of on-linearity and outliers, and give conflicting conclusions. In this paper, we propose a visualization-based method to improve the mutual fund analysis, where a new visual analytical tool, the density-based distribution map, is applied. The new visual representations greatly help to understand the critical relations, reveal the deficiency of current analytical algorithms,and support mutual funds selection. The tool is used to perform an expert financial analysis, and establish a fund selection strategy from a real-world database of the US stock funds. Our method gains the admiration and support from professionals in the finance field, they embrace it as a potential investment analysis tool for mutual fund managers, financial planners, and investors.","Title: Visual analysis for mutual fund performance\nYear: 2008\n\nAbstract: Mutual funds are one of the most important investment instruments available. However, choosing among mutual funds is not an easy task because they vary in many different dimensions, such as asset size, turnover and fee structure, and these characteristics may affect fund returns. It is thus important to understand the relation between fund performance and these properties. In this work, we use a new visual analytical tool, the density-based distribution map, to assist in this task. By visualizing various important fund characteristics from a real-world database of the US stock funds, our new visual representations greatly help understand the relation between fund characteristics and returns.","Title: Visualizing Hidden Themes of Taxi Movement with Semantic Transformation\nYear: 2014\n\nAbstract: A new methodology is developed to discover and analyze the hidden knowledge of massive taxi trajectory data within a city. This approach creatively transforms the geographic coordinates (i.e. latitude and longitude) to street names reflecting contextual semantic information. Consequently, the movement of each taxi is studied as a document consisting of the taxi traversed street names, which enables semantic analysis of massive taxi data sets as document corpora. Hidden themes, namely taxi topics, are identified through textual topic modeling techniques. The taxi topics reflect urban mobility patterns and trends, which are displayed and analyzed through a visual analytics system. The system integrates interactive visualization tools, including taxi topic maps, topic routes, street clouds and parallel coordinates, to visualize the probability-based topical information. Urban planners, administration, travelers, and drivers can conduct their various knowledge discovery tasks with direct semantic and visual assists. The effectiveness of this approach is illustrated by case studies using a large taxi trajectory data set acquired from 21, 360 taxis in a city.","Title: A Three Dimensional Foot Placement Planner For Locomotion In Very Rough Terrains\nYear: 2012\n\nAbstract: Maneuvering through 3D structures nimbly is pivotal to the advancement of legged locomotion. However, few methods have been developed that can generate 3D gaits in those terrains and fewer if none can be generalized to control dynamic maneuvers. In this study, foot placement planning for dynamic locomotion traversing irregular terrains is explored in three dimensional space. Given boundary values of the center of mass' apexes during the gait, sagittal and lateral phase-plane trajectories are predicted based on multi-contact and inverted pendulum dynamics. To deal with the nonlinear dynamics of the contact motions and their dimensionality, we plan a geometric surface of motion beforehand and rely on numerical integration to solve the models. In particular, we combine multi-contact and prismatic inverted pendulum models to resolve feet transitions between steps, allowing to produce trajectory patterns similar to those observed in human locomotion. Our contributions lay in the following points: (1) the introduction of non planar surfaces to characterize the center of mass' geometric behavior; (2) an automatic gait planner that simultaneously resolves sagittal and lateral feet placements; (3) the introduction of multi-contact dynamics to smoothly transition between steps in the rough terrains.","Title: The magic volume lens: an interactive focus+context technique for volume rendering\nYear: 2005\n\nAbstract: The size and resolution of volume datasets in science and medicine are increasing at a rate much greater than the resolution of the screens used to view them. This limits the amount of data that can be viewed simultaneously, potentially leading to a loss of overall context of the data when the user views or zooms into a particular area of interest. We propose a focus+context framework that uses various standard and advanced magnification lens rendering techniques to magnify the features of interest, while compressing the remaining volume regions without clipping them away completely. Some of these lenses can be interactively configured by the user to specify the desired magnification patterns, while others are feature-adaptive. All our lenses are accelerated on the GPU. They allow the user to interactively manage the available screen area, dedicating more area to the more resolution-important features.","Title: STREAMIT: Dynamic visualization and interactive exploration of text streams\nYear: 2011\n\nAbstract: Text streams demand an effective, interactive, and on-the-fly method to explore the dynamic and massive data sets, and meanwhile extract valuable information for visual analysis. In this paper, we propose such an interactive visualization system that enables users to explore streaming-in text documents without prior knowledge of the data. The system can constantly incorporate incoming documents from a continuous source into existing visualization context, which is \"physically\" achieved by minimizing a potential energy defined from similarities between documents. Unlike most existing methods, our system uses dynamic keyword vectors to incorporate newly-introduced keywords from data streams. Furthermore, we propose a special keyword importance that makes it possible for users to adjust the similarity on-the-fly, and hence achieve their preferred visual effects in accordance to varying interests, which also helps to identify hot spots and outliers. We optimize the system performance through a similarity grid and with parallel implementation on graphics hardware (GPU), which achieves instantaneous animated visualization even for a very large data collection. Moreover, our system implements a powerful user interface enabling various user interactions for in-depth data analysis. Experiments and case studies are presented to illustrate our dynamic system for text stream exploration.","Title: Distance Field Transform with an Adaptive Iteration Method\nYear: 2009\n\nAbstract: We propose a novel distance field transform method based on an iterative method adaptively performed on an evolving active band. Our method utilizes a narrow band to store active grid points being computed. Unlike the conventional fast marching method, we do not maintain a priority queue, and instead, perform iterative computing inside the band. This new algorithm alleviates the programming complexity and the data-structure (e.g. a heap) maintenance overhead, and leads to a parallel amenable computational process. During the active band propagating from a starting boundary layer, each grid point stays in the band for a lifespan time, which is determined by analyzing the particular geometric property of the grid structure. In this way, we find the Face-Centered Cubic (FCC) grid is a good 3D structure for distance transform. We further develop a multiple-segment method for the band propagation, achieving the computational complexity of O(m . N) with a segment-related constant m.","Title: A Bistatic SAR Image Intensity Model for the Composite Ship–Ocean Scene\nYear: 2015\n\nAbstract: Based on the scattering mechanisms of multipath, a bistatic synthetic aperture radar (Bis-SAR) image intensity model for the composite ship-ocean (or other metallic targets with ocean) scene is developed in this paper through reasonably dealing with the path lengths of transmitter and receiver to the ship target. To get a Bis-SAR image intensity model for the composite ship-ocean scene, the Bis-SAR image intensity distribution for the ocean surface is analyzed, and the facet scattering model is used to give the individual returns from separate facets. In addition, the influence of velocity bunching (VB) modulation of long ocean waves on the distribution of radar cross section is also discussed. Finally, Bis-SAR imagery simulations of ocean wave and the composite ship-ocean scene are illustrated, and the results show that the proposed Bis-SAR image intensity model can be reasonable and the interaction effects between the ship and sea surface can make significant contributions to the Bis-SAR intensity.","Title: Assessing Whole-Body Operational Space Control in a Point-Foot Series Elastic Biped: Balance on Split Terrain and Undirected Walking.\nYear: 2015\n\nAbstract: In this paper we present advancements in control and trajectory generation for agile behavior in bipedal robots. We demonstrate that Whole-Body Operational Space Control (WBOSC), developed a few years ago, is well suited for achieving two types of agile behaviors, namely, balancing on a high pitch split terrain and achieving undirected walking on flat terrain. The work presented here is the first implementation of WBOSC on a biped robot, and more specifically a biped robot with series elastic actuators. We present and analyze a new algorithm that dynamically balances point foot robots by choosing footstep placements. Dealing with the naturally unstable dynamics of these type of systems is a difficult problem that requires both the controller and the trajectory generation algorithm to operate quickly and efficiently. We put forth a comprehensive development and integration effort: the design and construction of the biped system and experimental infrastructure, a customization of WBOSC for the agile behaviors, and new trajectory generation algorithms. Using this custom built controller, we conduct, for first time, an experiment in which a biped robot balances in a high pitch split terrain, demonstrating our ability to precisely regulate internal forces using force sensing feedback techniques. Finally, we demonstrate the stabilizing capabilities of our online trajectory generation algorithm in the physics-based simulator and through physical experiments with a planarized locomotion setup.","Title: A visual reasoning approach for data-driven transport assessment on urban roads\nYear: 2014\n\nAbstract: Transport assessment plays a vital role in urban planning and traffic control, which are influenced by multi-faceted traffic factors involving road infrastructure and traffic flow. Conventional solutions can hardly meet the requirements and expectations of domain experts. In this paper we present a data-driven solution by leveraging a visual analysis system to evaluate the real traffic situations based on taxi trajectory data. A sketch-based visual interface is designed to support dynamic query and visual reasoning of traffic situations within multiple coordinated views. In particular, we propose a novel road-based query model for analysts to interactively conduct evaluation tasks. This model is supported by a bi-directional hash structure, TripHash, which enables real-time responses to the data queries over a huge amount of trajectory data. Case studies with a real taxi GPS trajectory dataset (> 30GB) show that our system performs well for on-demand transport assessment and reasoning.","Title: Optimizing offline access to social network content on mobile devices\nYear: 2014\n\nAbstract: In this paper, we explore the problem of supporting efficient access to social media contents on social network sites for mobile devices without requiring mobile users to be online all the time. We propose and implement a broker/proxy based architecture that stages data at a broker/proxy, and selectively downloads to the mobile device only those contents that have a high likelihood of being viewed. The system determines the relevance of social media updates that continuously arrive (e.g., Facebook friend updates) for each user. Using knowledge of this relevance and current network/system conditions, we develop scheduling algorithms that determine which social contents are sent to the devices. We develop an Android app providing offline access to Facebook. Our experimental results indicate that our system is energy efficient, which saves energy by 6.9 times for WiFi and 9.1 times for cellular connections. We also use data traces gathered from our app to further drive extensive simulation based evaluations which show that our proposed algorithms provide efficient facilities for tuning the system's performance.","Title: Feedback parameter selection for impedance control of series elastic actuators\nYear: 2014\n\nAbstract: The interest of series elastic actuators (SEAs) for legged robots has recently increased to achieve compliant interactions and efficient gaits. However, control of legged robots with SEAs is difficult due to the need to design controllers that take into account both torque and impedance feedback loops. The work presented here addresses this issue by proposing a critically-damped fourth order system gain selection criterion for a cascaded SEA control structure with inner torque and outer impedance feedback loops. Velocity filtering and feedback delays are taken into consideration for stability and impedance performance analysis. We observe and analyze the interdependence between torque and impedance feedback gains to achieve the desired closed loop performance. Based on this analysis we derive a simple gain design criterion to maximize the tracking performance of SEAs. Our final goal is to maximize the output impedance capabilities of SEAs in order to fulfill a wide range of application needs. In contrast to low impedance design studies, we focus here specifically on achieving the highest possible impedance gains of SEAs. Finally, experiments using our UT-SEA are conducted to verify our proposed approach. This study serves as a stepping stone towards utilizing and designing humanoid robots with SEA actuators for mobile behaviors and interaction with cluttered and unknown environments.","Title: Parkinson Data Analysis and Interpretation with Data Visualization Methods.\nYear: 2014\n\nAbstract: Information Visualization has been used in many areas and now its applications are growing each day. Modelling and visualization psychological processes, based on the analysis of psychological data can be a real necessary for all experts in this field. In this article we use PCA and person fit statistical for analyzing data, and some visualization tools for modeling to provide some visualizations of the Parkinson patient's information. The results show some meaningful relations between BMI, Age in one side and percentage of some Parkinson patient features that can be appear in men and women on the other side.","Title: TenniVis: Visualization for Tennis Match Analysis\nYear: 2014\n\nAbstract: Existing research efforts into tennis visualization have primarily focused on using ball and player tracking data to enhance professional tennis broadcasts and to aid coaches in helping their students. Gathering and analyzing this data typically requires the use of an array of synchronized cameras, which are expensive for non-professional tennis matches. In this paper, we propose TenniVis, a novel tennis match visualization system that relies entirely on data that can be easily collected, such as score, point outcomes, point lengths, service information, and match videos that can be captured by one consumer-level camera. It provides two new visualizations to allow tennis coaches and players to quickly gain insights into match performance. It also provides rich interactions to support ad hoc hypothesis development and testing. We first demonstrate the usefulness of the system by analyzing the 2007 Australian Open men's singles final. We then validate its usability by two pilot user studies where two college tennis coaches analyzed the matches of their own players. The results indicate that useful insights can quickly be discovered and ad hoc hypotheses based on these insights can conveniently be tested through linked match videos.","Title: A Bistatic Synthetic Aperture Radar Imagery Simulation of Maritime Scene Using the Extended Nonlinear Chirp Scaling Algorithm\nYear: 2013\n\nAbstract: A bistatic synthetic aperture radar (Bis-SAR) imagery simulation of an extended maritime scene is presented. An efficient facet scattering model is developed to collect the raw coupling scattering data from a ship located on sea surface. Then, to avoid the inefficiency of time-domain algorithms and the azimuth-invariant limit of conventional frequency-domain (FD) methods in the bistatic case, an extended nonlinear chirp scaling (NLCS) algorithm is proposed to handle the bistatic data collected from this facet scattering model. The perfect Bis-SAR simulation results of the ship located on the sea surface could prove the validity of the proposed algorithms as well as the practicability of the model for the Bis-SAR imagery with large squint angle in the FD approach.","Title: TrajGraph: A Graph-Based Visual Analytics Approach to Studying Urban Network Centralities Using Taxi Trajectory Data\nYear: 2016\n\nAbstract: We propose TrajGraph, a new visual analytics method, for studying urban mobility patterns by integrating graph modeling and visual analysis with taxi trajectory data. A special graph is created to store and manifest real traffic information recorded by taxi trajectories over city streets. It conveys urban transportation dynamics which can be discovered by applying graph analysis algorithms. To support interactive, multiscale visual analytics, a graph partitioning algorithm is applied to create region-level graphs which have smaller size than the original street-level graph. Graph centralities, including Pagerank and betweenness, are computed to characterize the time-varying importance of different urban regions. The centralities are visualized by three coordinated views including a node-link graph view, a map view and a temporal information view. Users can interactively examine the importance of streets to discover and assess city traffic patterns. We have implemented a fully working prototype of this approach and evaluated it using massive taxi trajectories of Shenzhen, China. TrajGraph's capability in revealing the importance of city streets was evaluated by comparing the calculated centralities with the subjective evaluations from a group of drivers in Shenzhen. Feedback from a domain expert was collected. The effectiveness of the visual interface was evaluated through a formal user study. We also present several examples and a case study to demonstrate the usefulness of TrajGraph in urban transportation analysis.","Title: Visual summarization of image collections by fast RANSAC\nYear: 2016\n\nAbstract: In this paper we propose a novel approach to select a summary set of images from a large image collection by improved Random Sample Consensus (RANSAC) and Affinity Propagation (AP) clustering. It can automatically select a small set of representatives to highlight all the significant visual properties of a given image collection. The proposed framework mainly composes four stages. First, the scale-invariant feature of each image is extracted by Scale Invariant Feature Transform (SIFT). Second, keypoints of two images are matched and ranked based on nearest neighbor ratio. The representative dataset of RANSAC is established by a minimal number of optimal matches. Third, the target homographic matrix is fitted based on the representative dataset. Mismatches are filtered out via the homographic matrix. Finally, summarization is automatically formulated as an optimization framework by AP clustering. We conduct experiments on a set of Paris which is consisting of 1000 images downloaded from Flickr. The results show that the proposed approach significantly outperforms other methods.","Title: TrajGraph: A Graph-Based Visual Analytics Approach to Studying Urban Network Centralities Using Taxi Trajectory Data\nYear: 2016\n\nAbstract: AbstractWe propose TrajGraph, a new visual analytics method, for studying urban mobility patterns by integrating graph modeling and visual analysis with taxi trajectory data. A special graph is created to store and manifest real traffic information recorded by taxi trajectories over city streets. It conveys urban transportation dynamics which can be discovered by applying graph analysis algorithms. To support interactive, multiscale visual analytics, a graph partitioning algorithm is applied to create region-level graphs which have smaller size than the original street-level graph. Graph centralities, including Pagerank and betweenness, are computed to characterize the time-varying importance of different urban regions. The centralities are visualized by three coordinated views including a node-link graph view, a map view and a temporal information view. Users can interactively examine the importance of streets to discover and assess city traffic patterns. We have implemented a fully working prototype of this approach and evaluated it using massive taxi trajectories of Shenzhen, China. TrajGraph's capability in revealing the importance of city streets was evaluated by comparing the calculated centralities with the subjective evaluations from a group of drivers in Shenzhen. Feedback from a domain expert was collected. The effectiveness of the visual interface was evaluated through a formal user study. We also present several examples and a case study to demonstrate the usefulness of TrajGraph in urban transportation analysis.","Title: A Framework for Planning and Controlling Non-Periodic Bipedal Locomotion.\nYear: 2015\n\nAbstract: This study presents a theoretical framework for planning and controlling agile bipedal locomotion based on robustly tracking a set of non-periodic apex states. Based on the prismatic inverted pendulum model, we formulate a hybrid phase-space planning and control framework which includes the following key components: (1) a step transition solver that enables dynamically tracking non-periodic apex or keyframe states over various types of terrains, (2) a robust hybrid automaton to effectively formulate planning and control algorithms, (3) a phase-space metric to measure distance to the planned locomotion manifolds, and (4) a hybrid control method based on the previous distance metric to produce robust dynamic locomotion under external disturbances. Compared to other locomotion frameworks, we have a larger focus on non-periodic gait generation and robustness metrics to deal with disturbances. Such focus enables the proposed control framework to robustly track non-periodic apex states over various challenging terrains and under external disturbances as illustrated through several simulations. Additionally, it allows a bipedal robot to perform non-periodic bouncing maneuvers over disjointed terrains.","Title: Hybrid multi-contact dynamics for wedge jumping locomotion behaviors\nYear: 2015\n\nAbstract: Legged robots naturally exhibit continuous and discrete dynamics when maneuvering over level-ground and uneven terrains. In recent years, numerous studies have focused on locomotion hybrid dynamics. However, locomotion on more challenging terrains such as split wedges in Figure 1 has rarely been explored, let alone its hybrid dynamics. In this study, we specifically focus on a two-phase hybrid automaton formulation for this highly steep wedge locomotion. This automaton incorporates both multi-contact and flight single contact phase motions. To dynamically balance and jump upwards on this wedge, an aperiodic phase space planning is used for trajectory generations. Three control strategies are employed simultaneously: internal force control, linear and angular momentum control. Finally, simulation results are shown to verify our strategy's effectiveness.","Title: SmartSource: A Mobile Q&A Middleware Powered by Crowdsourcing.\nYear: 2015\n\nAbstract: In this paper, we introduce Smart Source, a crowd sourcing based mobile Question & Answer (Q&A) system that aims to provide mobile information seekers with timely, trustworthy and accurate answers while ensuring that information providers are not inappropriately burdened. We tackle this challenge by taking advantage of both static and dynamic context and semantics from mobile users (e.g., Geolocation, social network, expertise/interest, device sensor profiles, battery level) to identify sources of information (i.e., Workers) that are trusted by the user and accurate enough for the questions at hand. Given a question, the Smart Source broker middleware executes a scalable and efficient worker selection algorithm that uses a Lyapunov optimization framework to maximize the utility of worker selection while guaranteeing the stability of the overall system. An associated assignor selection is used to scale the selection process to a large number of users. We implement the Smart Source prototype system on an Android test bed and thoroughly evaluate the system using real world applications and data, in particular those that involve geospatial questions and answers. Evaluation results indicate that Smart Source is efficient and provides superior worker selection compared to baseline approaches. Smart Source is also highly customizable: it employs a general utility function and provides a control knob to tradeoff the optimality and responding time. We believe that Smart Source will pave a way for new mechanisms of interaction among mobile users.","Title: Enabling offline access to Facebook streams on mobile devices\nYear: 2013\n\nAbstract: The recent years have witnessed the wild success of social networks and social media sites such as Facebook, Twitter, LinkedIn, Google+, and Instagram -- indeed, many people rely on these social networks to communicate with their friends, family and community on a day to day basis. Via these sites, users exchange rich media contents, such as video, audio, and images for an enhanced user experience. With the growing popularity of mobile communications, users connect to these social networks using mobile devices (e.g., smartphones, tablets) and expect to derive the same experience no matter how and where they connect. It is reported that 93% of Android smartphone users in India use social networks on their smartphones [6]. Another survey, done in Canada, shows that 61% of users access Facebook through mobile devices [2]. These market reports indicate that social media streams, carrying rich content, have become key aspects of how people view information and how society interacts today.","Title: Blowing in the wind\nYear: 2003\n\nAbstract: We present an approach for simulating the natural dynamics that emerge from the coupling of a flow field to lightweight, mildly deformable objects immersed within it. We model the flow field using a Lattice Boltzmann Model (LBM) extended with a subgrid model and accelerate the computation on commodity graphics hardware to achieve real-time simulations. We demonstrate our approach using soap bubbles and a feather blown by wind fields, yet our approach is general enough to apply to other light-weight objects. The soap bubbles illustrate Fresnel reflection, reveal the dynamics of the unseen flow field in which they travel, and display spherical harmonics in their undulations. The free feather floats and flutters in response to lift and drag forces. Our single bubble simulation allows the user to directly interact with the wind field and thereby influence the dynamics in real time.","Title: RichNote: Adaptive Selection and Delivery of Rich Media Notifications to Mobile Users\nYear: 2016\n\nAbstract: In recent years, notification services for social networks, mobile apps, messaging systems and other electronic services have become truly ubiquitous. When a new content becomes available, the service sends an instant notification to the user. When the content is produced in massive quantities, and it includes both large-size media and a lot of meta-information, it gives rise to a major challenge of selecting content to notify about and information to include in such notifications. We tackle three important challenges in realizing rich notification delivery: (1) content and presentation utility modeling, (2) notification selection and (3) scheduling of delivery. We consider a number of progressive presentation levels for the content. Since utility is subjective and hard to model, we rely on real data and user surveys. We model the content utility by learning from large-scale real world data collected from Spotify music streaming service. For the utility of the presentation levels we rely on user surveys. Blending these two techniques together, we derive utility of notifications with different presentation levels. We then model the selection and delivery of rich notifications as an optimization problem with a goal to maximize the utility of notifications under resource budget constraints. We validate our system with large-scale simulations driven by the real-world de-identified traces obtained from Spotify. With the help of several baseline approaches we show that our solution is adaptive and resource efficient.","Title: A visual analytics approach to high-dimensional logistic regression modeling and its application to an environmental health study\nYear: 2016\n\nAbstract: In the domain of epidemiology, logistic regression modeling is widely used to explain the relationships among explanatory variables and dichotomous outcome variables. However, logistic regression modeling faces challenges such as overfitting, confounding, and multicollinearity when there is a large number of explanatory variables. For example, in the birth defect study presented in this paper, variable selection for building high quality models to identify risk factors from hundreds of pollutant variables is difficult. To address this problem, we propose a novel visual analytics approach to logistic regression modeling for high-dimensional datasets. It leverages the traditional modeling pipeline by providing (1) intuitive visualizations for inspecting statistical indicators and the relationships among the variables and (2) a seamless, effective dimension reduction pipeline for selecting variables for inclusion in high quality logistic regression models. A fully working prototype of this approach has been developed and successfully applied to the birth defect study, which illustrates its effectiveness and efficiency. Its application in an insurance policy study and feedback from domain experts further demonstrate its usefulness.","Title: Spot-tracking lens: A zoomable user interface for animated bubble charts\nYear: 2016\n\nAbstract: Zoomable user interfaces are widely used in static visualizations and have many benefits. However, they are not well supported in animated visualizations due to problems such as change blindness and information overload. We propose the spot-tracking lens, a new zoomable user interface for animated bubble charts, to tackle these problems. It couples zooming with automatic panning and provides a rich set of auxiliary techniques to enhance its effectiveness. Our preliminary user studies suggested that, besides allowing users to examine detail information, it can be an engaging approach to exploratory analysis for dynamic data.","Title: SemanticTraj: A New Approach to Interacting with Massive Taxi Trajectories.\nYear: 2017\n\nAbstract: Massive taxi trajectory data is exploited for knowledge discovery in transportation and urban planning. Existing tools typically require users to select and brush geospatial regions on a map when retrieving and exploring taxi trajectories and passenger trips. To answer seemingly simple questions such as “What were the taxi trips starting from Main Street and ending at Wall Street in the morning?” or “Where are the taxis arriving at the Art Museum at noon typically coming from?”, tedious and time consuming interactions are usually needed since the numeric GPS points of trajectories are not directly linked to the keywords such as “Main Street”, “Wall Street”, and “Art Museum”. In this paper, we present SemanticTraj, a new method for managing and visualizing taxi trajectory data in an intuitive, semantic rich, and efficient means. With SemanticTraj, domain and public users can find answers to the aforementioned questions easily through direct queries based on the terms. They can also interactively explore the retrieved data in visualizations enhanced by semantic information of the trajectories and trips. In particular, taxi trajectories are converted into taxi documents through a textualization transformation process. This process maps GPS points into a series of street/POI names and pick-up/drop-off locations. It also converts vehicle speeds into user-defined descriptive terms. Then, a corpus of taxi documents is formed and indexed to enable flexible semantic queries over a text search engine. Semantic labels and meta-summaries of the results are integrated with a set of visualizations in a SemanticTraj prototype, which helps users study taxi trajectories quickly and easily. A set of usage scenarios are presented to show the usability of the system. We also collected feedback from domain experts and conducted a preliminary user study to evaluate the visual system.","Title: VesselMap: A web interface to explore multivariate vascular data.\nYear: 2016\n\nAbstract: Abstract Hemodynamics plays a key role in the pathological evolution of vascular diseases such as vascular stenosis, plaques and aneurysms. Augmented visualization of relevant hemodynamic and geometric data accelerates engineering designs of diagnostic and therapeutic methods for those vascular diseases. However, four dimensional (4D) hemodynamic data are intrinsically complex. Consequently, exploration of this information has not been streamlined, despite its importance. In this paper, we propose a web interface to explore multivariate hemodynamic data, thereby facilitating the visualization of spatial and temporal relationships among those hemodynamic parameters of interest. The main thrust of this web system is the proposed VesselMap methodology, a 2D representation of vessel structures that provides an overview of all query results without any visual occlusions. Furthermore, in this framework, quantile–quantile plot was also used to compare spatial variations in parameter distributions, thereby greatly aiding in extracting local characteristics of hemodynamic parameters. Using “patient-specific” computational fluid dynamics (CFD) simulations, realistic flow velocity fields were obtained. Based on those CFD-simulated velocity fields, we performed an empirical evaluation to confirm the usefulness of our approach for biomedical engineering applications. We concluded that the proposed VesselMap methodology allowed users to rapidly interact with hemodynamic data of interest, enhancing efficacy of information retrieval.","Title: Crowdsourced Mobile Data Transfer with Delay Bound.\nYear: 2016\n\nAbstract: In this article, we design a crowdsourcing system, CrowdMAC, where mobile devices form a local community or marketplace to share network access and transfer data for each other. CrowdMAC enables (i) mobile clients to select and exploit multiple mobile hotspots in its vicinity for data transfer and (ii) mobile hotspots to open their cellular connectivity to admit/serve delay-bounded requests from mobile users for a fee. The evaluations of CrowdMAC indicate that (i) mobile clients can tune preferred trade-offs between cost and delay through a control knob, (ii) mobile hotspots comply with all delay bounds, and (iii) the system ensures stable and efficient transfer.","Title: Stabilizing Series-Elastic Point-Foot Bipeds Using Whole-Body Operational Space Control.\nYear: 2016\n\nAbstract: Whole-body operational space controllers (WBOSCs) are versatile and well suited for simultaneously controlling motion and force behaviors, which can enable sophisticated modes of locomotion and balance. In this paper, we formulate a WBOSC for point-foot bipeds with series-elastic actuators (SEA) and experiment with it using a teen-size SEA biped robot. Our main contributions are on devising a WBOS...","Title: A Planning and Control Framework for Humanoid Systems: Robust, Optimal, and Real-time Performance.\nYear: 2017\n\nAbstract: Humanoid robots are increasingly demanded to operate in interactive and human-surrounded environments while achieving sophisticated locomotion and manipulation tasks. To accomplish these tasks, roboticists unremittingly seek for advanced methods that generate whole-body coordination behaviors and meanwhile fulfill various planning and control objectives. Undoubtedly, these goals pose fundamental challenges to the robotics and control community. To take an incremental step towards reducing the performance gap between theoretical foundations and real implementations, we present a planning and control framework for the humanoid, especially legged robots, for achieving high performance and generating agile motions. A particular concentration is on the robust, optimal and real-time performance. This framework constitutes three hierarchical layers: First, we present a robust optimal phase-space planning framework for dynamic legged locomotion over rough terrain. This framework is a hybrid motion planner incorporating a series of pivotal components. Second, we take a step toward formally synthesizing high-level reactive planners for whole-body locomotion in constrained environments. We formulate a two-player temporal logic game between the contact planner and its possibly-adversarial environment. Third, we propose a distributed control architecture for the latency-prone humanoid robotic systems. A central experimental phenomenon is observed that the stability of high impedance distributed controllers is highly sensitive to damping feedback delay but much less to stiffness feedback delay. We pursue a detailed analysis of the distributed controllers where damping feedback effort is executed in proximity to the control plant, and stiffness feedback effort is implemented in a latency-prone centralized control process.","Title: High-Level Planner Synthesis For Whole-Body Locomotion In Unstructured Environments\nYear: 2016\n\nAbstract: Contact-based decision and planning methods are increasingly being sought for task execution in humanoid robots. However, formal methods from the verification and synthesis communities have not been yet incorporated into the motion planning sequence for complex mobility behaviors in humanoid robots. This study takes a step toward formally synthesizing high-level reactive task planners for whole-body locomotion in unstructured environments. We formulate a two player temporal logic game between the contact planner and its possibly adversarial environment. The resulting discrete planner satisfies the given task specifications expressed in a fragment of temporal logic. The resulting commands are executed by a low-level 3D phase-space motion planner algorithm. We devise various low-level locomotion modes based on centroidal momentum dynamics. Provable correctness of the low-level execution of the synthesized discrete task planner is guaranteed through the so-called simulation relations. Simulations of dynamic locomotion in unstructured environments support the effectiveness of the hierarchical planner protocol.","Title: Visual Analytics of Mobility and Transportation: State of the Art and Further Research Directions\nYear: 2017\n\nAbstract: AbstractMany cities and countries are now striving to create intelligent transportation systems that utilize the current abundance of multisource and multiform data related to the functionality and the use of transportation infrastructure to better support human mobility, interests, and lifestyles. Such intelligent transportation systems aim to provide novel services that can enable transportation consumers and managers to be better informed and make safer and more efficient use of the infrastructure. However, the transportation domain is characterized by both complex data and complex problems, which calls for visual analytics approaches. The science of visual analytics is continuing to develop principles, methods, and tools to enable synergistic work between humans and computers through interactive visual interfaces. Such interfaces support the unique capabilities of humans (such as the flexible application of prior knowledge and experiences, creative thinking, and insight) and couple these abilities with machines’ computational strengths, enabling the generation of new knowledge from large and complex data. In this paper, we describe recent developments in visual analytics that are related to the study of movement and transportation systems and discuss how visual analytics can enable and improve the intelligent transportation systems of the future. We provide a survey of literature from the visual analytics domain and organize the survey with respect to the different types of transportation data, movement and its relationship to infrastructure and behavior, and modeling and planning. We conclude with lessons learned and future directions, including social transportation, recommender systems, and policy implications.","Title: Reconstructing images corrupted by noise based on D-S evidence theory.\nYear: 2017\n\nAbstract: In this paper, a new algorithm of noise reduction for image based on evidence theory is proposed. The values of all pixels are restricted in interval [0, 1], and set of data in each column is a term of mass function, which can be calculated by D–S composition rule. Judging noise can be achieved by comparing with the value of pixel in middle and of the current one. The noise will be removed by substituting the current value with value computed. An improved accelerated algorithm is also presented by sample window of 2 × 2. As a measure of conflict K with greater value shows that there would be noises within the current sample window. At last, Experiment image “Lena” with additive noise shows as a test sample, that better result can be achieved with the algorithm.","Title: Coverage area detection based on Voronoi diagram in wireless sensor network of metro\nYear: 2016\n\nAbstract: The layout of sensor nodes has been playing an important role in health detection of metro tunnel. If the density of nodes are too much, the redundant information would be produced. Oppositely, the completeness cannot be ensured. The research of this paper is to detect the coverage area of wireless sensor network in metro tunnel, which is based on spatial density network Voronoi diagram. The new diagram is extended by classic Voronoi diagrams, and the discrete construction method is introduced. In the end of the paper, the real example indicated that the research has a practical meaning.","Title: UrbanFACET: Visually Profiling Cities from Mobile Device Recorded Movement Data of Millions of City Residents.\nYear: 2017\n\nAbstract: Cities are living systems where urban infrastructures and their functions are defined and evolved due to population behaviors. Profiling the cities and functional regions has been an important topic in urban design and planning. This paper studies a unique big data set which includes daily movement data of tens of millions of city residents, and develop a visual analytics system, namely UrbanFACET, to discover and visualize the dynamical profiles of multiple cities and their residents. This big user movement data set, acquired from mobile usersu0027 agnostic check-ins at thousands of phone APPs, is well utilized in an integrative study and visualization together with urban structure (e.g., road network) and POI (Point of Interest) distributions. In particular, we novelly develop a set of information-theory based metrics to characterize the mobility patterns of city areas and groups of residents. These multifaceted metrics including Fluidity, vibrAncy, Commutation, divErsity, and densiTy (FACET) which categorize and manifest hidden urban functions and behaviors. UrbanFACET system further allows users to visually analyze and compare the metrics over different areas and cities in metropolitan scales. The system is evaluated through both case studies on several big and heavily populated cities, and user studies involving real-world users.","Title: Guest Editorial Introduction to the Special Issue on Visual Analysis for ITS.\nYear: 2017\n\nAbstract: Sensing technologies, social media, and large-scale computing infrastructures have produced a variety of traffic and transportation data, e.g., human mobility, mobile trajectories, mobile phone calls, traffic, and geographical data. Despite the wealth of research on intelligent transportation systems, contemporary analytical tools are often inadequate for handling the data with the character of la...","Title: Towards understanding visually guided locomotion over complex and rough terrain: A phase-space planning method\nYear: 2017\n\nAbstract: As legged robots maneuver over increasingly complex and rough terrains, designing motion planners with the capability of predicting future footsteps becomes imperative. In turn, these planners provide a valuable tool for understanding the fundamental principles underlying human locomotion [2, 3]. In this study, we use our previously proposed phase-space planning framework [1] to analyze human walking over complex terrain. In particular, we highlight (i) the center of mass (CoM) apex-state-based feature of the phase-space planning, and (ii) the role of vision in CoM apex state selection during human walking over complex terrain [2].","Title: Robust optimal planning and control of non-periodic bipedal locomotion with a centroidal momentum model\nYear: 2017\n\nAbstract: AbstractThis study presents a theoretical method for planning and controlling agile bipedal locomotion based on robustly tracking a set of non-periodic keyframe states. Based on centroidal momentum dynamics, we formulate a hybrid phase-space planning and control method that includes the following key components: i a step transition solver that enables dynamically tracking non-periodic keyframe states over various types of terrain; ii a robust hybrid automaton to effectively formulate planning and control algorithms; iii a steering direction model to control the robot's heading; iv a phase-space metric to measure distance to the planned locomotion manifolds; and v a hybrid control method based on the previous distance metric to produce robust dynamic locomotion under external disturbances. Compared with other locomotion methodologies, we have a large focus on non-periodic gait generation and robustness metrics to deal with disturbances. This focus enables the proposed control method to track non-periodic keyframe states robustly over various challenging terrains and under external disturbances, as illustrated through several simulations.","Title: Using flow feature to extract pulsatile blood flow from 4D flow MRI images.\nYear: 2017\n\nAbstract: 4D flow MRI images make it possible to measure pulsatile blood flow inside deforming vessel, which is critical in accurate blood flow visualization, simulation, and evaluation. Such data has great potential to overcome problems in existing work, which usually does not reflect the dynamic nature of elastic vessels and blood flows in cardiac cycles. However, the 4D flow MRI data is often low-resolution and with strong noise. Due to these challenges, few efforts have been successfully conducted to extract dynamic blood flow fields and deforming artery over cardiac cycles, especially for small artery like carotid. In this paper, a robust flow feature, particularly the mean flow intensity is used to segment blood flow regions inside vessels from 4D flow MRI images in whole cardiac cycle. To estimate this flow feature more accurately, adaptive weights are added to the raw velocity vectors based on the noise strength of MRI imaging. Then, based on this feature, target arteries are tracked in at different time steps in a cardiac cycle. This method is applied to the clinical 4D flow MRI data in neck area. Dynamic vessel walls and blood flows are effectively generated in a cardiac cycle in the relatively small carotid arteries. Good image segmentation results on 2D slices are presented, together with the visualization of 3D arteries and blood flows. Evaluation of the method was performed by clinical doctors and by checking flow volume rates in the vertebral and carotid arteries.","Title: Impedance Control and Performance Measure of Series Elastic Actuators.\nYear: 2018\n\nAbstract: Series elastic actuators (SEAs) have become prevalent in torque-controlled robots in recent years to achieve compliant interactions with environments and humans. However, designing optimal impedance controllers and characterizing impedance performance for SEAs with time delays and filtering are still underexplored problems. This article addresses the controller design problem by devising a critica...","Title: Generating Chinese Poems from Images Based on Neural Network.\nYear: 2017\n\nAbstract: Chinese classical poetry generation from images is an overwhelmingly challenging work in the field of artificial intelligence. Inspired by recent advances in automatically generating description of an image and Chinese poem generation, in this paper, we present a generative model based on deep recurrent framework that describes images in the form of poems. Our model consists of two parts, one is to extract information according to the semantics presented in images, and the other is to generate each line of the poem incrementally according to the extracted semantic information from the images by a recurrent neural network. Experimental results thoroughly demonstrate the effectiveness of our approach by manual evaluation.","Title: Variable stiffness control of series elastic actuated biped locomotion.\nYear: 2018\n\nAbstract: This study investigates the problem of dynamic walking impact on a biped robot. Two online variable stiffness control algorithms, i.e., torque balance algorithm (TBA) and surface fitting algorithm (SFA), are proposed based on virtual spring leg to achieve compliant performance. These two algorithms target on solving the high nonlinearity commonly existing in legged robot actuators. A planar biped robot experiment platform is designed for testing the proposed variable stiffness control. The experiments compare the performance of TBA and SFA and verify that applying the variable stiffness control of a virtual spring leg is capable of effectively absorbing unforeseen ground impacts and thus improving stability and safety of walking biped robots.","Title: Enhancing Person Retrieval with Joint Person Detection, Attribute Learning, and Identification.\nYear: 2018\n\nAbstract: Person re-identification receives increasing attention in recent years. However, most works assume the persons have been well cropped from the whole scene images, and only focus on learning features and metrics. This paper considers the person re-identification problem in a real-world scenario, which should consider detection and identification simultaneously. This paper proposes a multi-task learning framework for person retrieval in the wild. Person attribute learning is exploited in our framework to enhance person retrieval. Our work consists of two main contributions: (1) we present a 11 image-level attribute annotations for each image in the large-scale PRW [ 27] dataset, and (2) we develop an end-to-end person retrieval framework which jointly learns person detector, attribute detectors, and visual embeddings in a multi-task learning manner. We evaluate the effectiveness of the proposed approach on two tasks, i.e. person attribute recognition and person re-identification. Experimental results have demonstrated the effectiveness of the proposed approach.","Title: A Battery Monitoring Ic With An Isolated Communication Interface For Electric Vehicles\nYear: 2018\n\nAbstract: This paper presents a Li-ion battery monitoring and protection IC suitable for monitoring 12 battery cells for clcctric vehicles (EVs). A two-wire, transformer based, isolated interface is proposed to provide the interface for the cascaded ICs. The interface uses the \"balanced\" two-wire technology and encodes the four SPI signals into DC-free pulse that can be coupled by a transformer, which features high-speed, low electromagnetic interference (EMI), and reliable data transmission. The IC was fabricated in a 0.18 mu m, 60 V BCD process, with a total chip area of 4.4 X 3.6 mm(2). Measurement results show that the proposed interface can achieve a data rate up to 1 Mbps. Meanwhile, the measured current consumption is less than 45 mu A in sleeping mode.","Title: Reactive Task and Motion Planning for Robust Whole-Body Dynamic Locomotion in Constrained Environments.\nYear: 2018\n\nAbstract: Contact-based decision and planning methods are becoming increasingly important to endow higher levels of autonomy for legged robots. Formal synthesis methods derived from symbolic systems have great potential for reasoning about high-level locomotion decisions and achieving complex maneuvering behaviors with correctness guarantees. This study takes a first step toward formally devising an architecture composed of task planning and control of whole-body dynamic locomotion behaviors in constrained and dynamically changing environments. At the high level, we formulate a two-player temporal logic game between the multi-limb locomotion planner and its dynamic environment to synthesize a winning strategy that delivers symbolic locomotion actions. These locomotion actions satisfy the desired high-level task specifications expressed in a fragment of temporal logic. Those actions are sent to a robust finite transition system that synthesizes a locomotion controller that fulfills state reachability constraints. This controller is further executed via a low-level motion planner that generates feasible locomotion trajectories. We construct a set of dynamic locomotion models for legged robots to serve as a template library for handling diverse environmental events. We devise a replanning strategy that takes into consideration sudden environmental changes or large state disturbances to increase the robustness of the resulting locomotion behaviors. We formally prove the correctness of the layered locomotion framework guaranteeing a robust implementation by the motion planning layer. Simulations of reactive locomotion behaviors in diverse environments indicate that our framework has the potential to serve as a theoretical foundation for intelligent locomotion behaviors.","Title: Distributed Impedance Control of Latency-Prone Robotic Systems with Series Elastic Actuation.\nYear: 2018\n\nAbstract: Robotic systems are increasingly relying on distributed feedback controllers to tackle complex and latency-prone sensing and decision problems. These demands come at the cost of a growing computational burden and, as a result, larger controller latencies. To maximize robustness to mechanical disturbances and achieve high control performance, we emphasize the necessity for executing damping feedback in close proximity to the control plant while allocating stiffness feedback in a latency-prone centralized control process. Additionally, series elastic actuators (SEAs) are becoming prevalent in torque-controlled robots during recent years to achieve compliant interactions with environments and humans. However, designing optimal impedance controllers and characterizing impedance performance for SEAs with time delays and filtering are still under-explored problems. The presented study addresses the optimal controller design problem by devising a critically-damped gain design method for a class of SEA cascaded control architectures, which is composed of outer-impedance and inner-torque feedback loops. Via the proposed controller design criterion, we adopt frequency-domain methods to thoroughly analyze the effects of time delays, filtering and load inertia on SEA impedance performance. These results are further validated through the analysis, simulation, and experimental testing on high-performance actuators and on an omnidirectional mobile base.","Title: Distributed filtering for time-varying networked systems with sensor gain degradation and energy constraint: a centralized finite-time communication protocol scheme.\nYear: 2018\n\nAbstract: This paper focuses on the distributed filtering problem for a class of time-varying networked systems with sensor gain degradation and energy constrained communication protocol. To satisfy the requirement of power consumption and reduce the schedule computing complexity, centralized cyclic finite-time communication strategy optimization is taken into account. The networked system considered in this paper consists of spatially distributed sensors linked to their neighbor sensors, where each sensor node suffers from different gain degradation, and the transmission decisions of all the communication channels obey the centralized transmission schedule strategy identically. First, we present scattered communication action based on single-sensor transmission modeling with an energy constraint. Subsequently, an optimal communication protocol considering expected average error covariance is derived between the target system and each sensor node over the distributed sensor systems, based on a centralized finite-time scheme. Finally, by transforming the overall estimation error covariance of the systems at each sampling time into quadratic form, a conditionally unbiased least-square recursive distributed filtering technique over the networked system is designed at each sensor node. The system stability condition under such an optimal schedule is also accomplished with bounded covariance. A numerical example is provided to demonstrate the utility and effectiveness of the distributed filtering technique using the proposed optimized energy constrained communication protocol.","Title: Novel Stability Analysis of Full Order Observer for Induction Motor Drive\nYear: 2018\n\nAbstract: Flux observation plays an important part in induction motor drive, among which full order observer is focused on mostly due to its excellent attributes, such as close loop simultaneous estimation of motor flux and speed, high immunity to motor parameter variation and so on. Just because flux observation and speed identification relate with each other, the system stability analysis is no easy to implement. So far, stability analysis was almost realized from the view of speed identification with flux amplitude though to be constant, which lacks in strict proof and not comprehensive, making flux observation stability not clear. In this paper, stability is made by decomposing observer system to two subsystem using two scale approach, with the rate of flux observation converging to its real counterpart differing from that of speed identification converging to its real counterpart substantially. Analysis is made of flux observation stability. Simulations validate the analysis.","Title: Efficient Numerical Full-Polarized Facet-Based Model for EM Scattering from Rough Sea Surface within a Wide Frequency Range.\nYear: 2019\n\nAbstract: A full-polarized facet based scattering model (FPFSM) for investigating the electromagnetic (EM) scattering by two-dimensional electrically large sea surfaces with high efficiency at high microwave bands is proposed. For this method, the scattering field over a large sea facet in a diffuse scattering region is numerically deduced according to the Bragg scattering mechanism. In regard to near specular directions, a novel approach is proposed to calculate the scattered field from a sea surface based on the second order small slope approximation (SSA-II), which saves computer memory considerably and is able to analyze the EM scattering by electrically large sea surfaces. The feasibility of this method in evaluating the radar returns from the sea surface is proved by comparing the normalized radar cross sections (NRCS) and the Doppler spectrum with the SSA-II. Then NRCS results in monostatic and bistatic configurations under different polarization states, scattering angles and wind speeds are analyzed as well as the Doppler spectrum at Ka-band. Numerical results show that the FPFSM is a reliable and efficient method to analyze the full-polarized scattering characteristics from electrically large sea surface within a wide frequency range.","Title: Adaptively Exploring Population Mobility Patterns in Flow Visualization.\nYear: 2017\n\nAbstract: Thanks to the ubiquitous cell phone use, we have never been so close to uncover population mobility patterns in urban area. While some researches utilize cellphone call records to mine population patterns, few works aim to depict population movement in adaptively spatial and temporal representations, i.e., from a community, a district in the city over an hour, a day to a week. In this paper, we co...","Title: Improved Rao-Blackwellised particle filter based on randomly weighted particle swarm optimization.\nYear: 2018\n\nAbstract: In this paper, a new Rao-Blackwellised particle filter simultaneous localization and mapping method based on randomly weighted particle swarm optimization is proposed in order to solve some problems in the Rao-Blackwellised particle filter, including the depletion of particles and the loss of the diversity in the process of resampling. The particle swarm optimization strategy is introduced in the modified algorithm, and the inertia weight is randomly set. Modified particle swarm optimization method is utilized to optimize the particle set in order to avoid particle degenerating and to keep the diversity. The proposed algorithm is simulated in the Qt platform. To verify the proposed method, the experiment is performed using turtlebot robots under the robot operating system. Results show that the proposed method is superior than extended Kalman filter based on simultaneous localization and mapping method.","Title: QuteVis: Visually Studying Transportation Patterns Using Multisketch Query of Joint Traffic Situations\nYear: 2021\n\nAbstract: QuteVis uses multisketch query and visualization to discover specific times and days in history with specified joint traffic patterns at different city locations. Users can use touch input devices to define, edit, and modify multiple sketches on a city map. A set of visualizations and interactions is provided to help users browse and compare retrieved traffic situations and discover potential influential factors. QuteVis is built upon a transport database that integrates heterogeneous data sources with an optimized spatial indexing and weighted similarity computation. An evaluation with real-world data and domain experts demonstrates that QuteVis is useful in urban transportation applications in modern cities.","Title: Fully parallelized Lattice Boltzmann scheme for fast extraction of biomedical geometry.\nYear: 2019\n\nAbstract: We develop a fully parallel numerical method which quickly performs 2D and 3D segmentation on GPU to extract anatomical structures from medical images. The algorithm solves the level set equations completely within a Lattice Boltzmann model (LBM). Compared with existing LBM-based segmentation approaches, a parallel distance field regularization is added to the LBM computing scheme to keep computation stable with large time step iteration. This approach also avoids external regularization which has been a major impediment to direct parallelization of level set evolution with LBM. It allows the whole computing process to be efficiently executed on GPU. Moreover, the method can be incorporated with different image features to adopt in various image segmentation tasks. Therefore, our method enables fully GPU accelerated geometric extraction from medical images, leading to high computing performance which is demanded in many practical applications. This method is used to exactly accurate 2D and 3D anatomical structures from many real world CT and MRI images. The achieved results can also directly feed required boundary information to LBM-based hemodynamics simulation.","Title: Sparsity-regularized feature selection for multi-class remote sensing image classification\nYear: 2020\n\nAbstract: Remote sensing image classification plays an important role in a wide range of applications and has caused widely concerns. During the last few years, great efforts have been made to develop a number of scene classification methods for remote sensing images. However, the existing remote sensing image classification methods do not perform satisfactorily in dealing with multi-class classification problems and rely heavily on the quality of data sets. These disadvantages seriously restrict the application of remote sensing image, including industrial research, analysis and calculation of land use and land coverage. To this end, this paper proposes a remote sensing image classification algorithm based on the sparse regularized feature learning method. Specifically, after constructing bag of features by using speeded up robust features extraction algorithm, direct sparsity optimization-based feature selection method is applied for selecting discriminative features, which is used for constructing support vector machine classifier model. The proposed algorithm has been evaluated and compared with other advanced feature selection methods on four public remote sensing image data sets. The experimental results demonstrate the effectiveness of our proposed image classification algorithm, which has been successfully applied to remote sensing image classification tasks.","Title: Robust Bipedal Locomotion Based on a Hierarchical Control Structure\nYear: 2019\n\nAbstract: To improve biped locomotion's robustness to internal and external disturbances, this study proposes a hierarchical structure with three control levels. At the high level, a foothold sequence is generated so that the Center of Mass (CoM) trajectory tracks a planned path. The planning procedure is simplified by selecting the midpoint between two consecutive Center of Pressure (CoP) points as the feature point. At the middle level, a novel robust hybrid controller is devised to drive perturbed system states back to the nominal trajectory within finite cycles without chattering. The novelty lies in that the hybrid controller is not subject to linear CoM dynamic constraints. The hybrid controller consists of two sub-controllers: an oscillation controller and a smoothing controller. For the oscillation controller, the desired CoM height is specified as a sine-shaped function, avoiding a new attractive limit cycle. However, this controller results in the inevitable chattering because of discontinuities. A smoothing controller provides continuous properties and thus can inhibit the chattering problem, but has a smaller region of attraction compared with the oscillation controller. A hybrid controller merges the two controllers for a smooth transition. At the low level, the desired CoM motion is defined as tasks and embedded in a whole body operational space (WBOS) controller to compute the joint torques analytically. The novelty of the low-level controller lies in that within the WBOS framework, CoM motion is not subject to fixed CoM dynamics and thus can be generalized.","Title: Unsupervised Video Summarization Via Clustering Validity Index\nYear: 2020\n\nAbstract: Although lots of the prior works have been proposed to solve the representative selection problem of video summarization, the main difficulty is still left for determining the optimal representatives' number of the raw videos that are not annotated. In this paper, we propose an unsupervised video summarization method by motion-based frame selection and a novel clustering validity indexes to determine the optimal representatives of the original video. The proposed framework segments shots and selects candidate frames by evaluating their forward and backward motion and can automatically select representatives to highlight all the significant visual properties. Shots are segmented uniformly and the frame with the largest motion is extracted in each segmentation to form the video candidate frame subset. Then Affinity Propagation combined with the validity index is used to automatically select the optimal representatives from the candidate frame subset. Our experimental result on several benchmark datasets demonstrates the robustness and effectiveness of our proposed method.","Title: Upsilon-Nonparallel Parametric Margin Fuzzy Support Vector Machine\nYear: 2021\n\nAbstract: Classification problem is an important research direction in machine learning. upsilon-nonparallel support vector machine (upsilon-NPSVM) is an important classifier used to solve classification problems. It is widely used because of its structural risk minimization principle, kernel trick, and sparsity. However, when solving classification problems, upsilon-NPSVM will encounter the problem of sample noises and heteroscedastic noise structure, which will affect its performance. In this paper, two improvements are made on the upsilon-NPSVM model, and a v-nonparallel parametric margin fuzzy support vector machine (parv-FNPSVM) is established. On the one hand, for the noises that may exist in the data set, the neighbor information is used to add fuzzy membership to the samples, so that the contribution of each sample to the classification is treated differently. On the other hand, in order to reduce the effect of heteroscedastic structure, an insensitive loss function is introduced. The advantages of the new model are verified through UCI machine learning standard data set experiments. Finally, Friedman test and Bonferroni-Dunn test are used to verify the statistical significance of it.","Title: Safe Reinforcement Learning With Stability Guarantee for Motion Planning of Autonomous Vehicles\nYear: 2021\n\nAbstract: Reinforcement learning with safety constraints is promising for autonomous vehicles, of which various failures may result in disastrous losses. In general, a safe policy is trained by constrained optimization algorithms, in which the average constraint return as a function of states and actions should be lower than a predefined bound. However, most existing safe learning-based algorithms capture s...","Title: A Visual Designer Of Layer-Wise Relevance Propagation Models\nYear: 2021\n\nAbstract: Layer-wise Relevance Propagation (LRP) is an emerging and widely-used method for interpreting the prediction results of convolutional neural networks (CNN). LRP developers often select and employ different relevance backpropagation rules and parameters, to compute relevance scores on input images. However, there exists no obvious solution to define a \"best\" LRP model. A satisfied model is highly reliant on pertinent images and designers' goals. We develop a visual model designer, named as VisLRPDesigner, to overcome the challenges in the design and use of LRP models. Various LRP rules are unified into an integrated framework with an intuitive workflow of parameter setup. VisLRPDesigner thus allows users to interactively configure and compare LRP models. It also facilitates relevance-based visual analysis with two important functions: relevance-based pixel flipping and neuron ablation. Several use cases illustrate the benefits of VisLRPDesigner. The usability and limitation of the visual designer is evaluated by LRP users.","Title: Terrain-Perception-Free Quadrupedal Spinning Locomotion on Versatile Terrains: Modeling, Analysis, and Experimental Validation\nYear: 2021\n\nAbstract: Dynamic quadrupedal locomotion over rough terrains reveals remarkable progress over the last few decades. Small-scale quadruped robots are adequately flexible and adaptable to traverse uneven terrains along the sagittal direction, such as slopes and stairs. To accomplish autonomous locomotion navigation in complex environments, spinning is a fundamental yet indispensable functionality for legged robots. However, spinning behaviors of quadruped robots on uneven terrain often exhibit position drifts. Motivated by this problem, this study presents an algorithmic method to enable accurate spinning motions over uneven terrain and constrain the spinning radius of the center of mass (CoM) to be bounded within a small range to minimize the drift risks. A modified spherical foot kinematics representation is proposed to improve the foot kinematic model and rolling dynamics of the quadruped during locomotion. A CoM planner is proposed to generate a stable spinning motion based on projected stability margins. Accurate motion tracking is accomplished with linear quadratic regulator (LQR) to bind the position drift during the spinning movement. Experiments are conducted on a small-scale quadruped robot and the effectiveness of the proposed method is verified on versatile terrains including flat ground, stairs, and slopes.","Title: Adversarially Regularized Policy Learning Guided by Trajectory Optimization.\nYear: 2022\n\nAbstract: Recent advancement in combining trajectory optimization with function approximation (especially neural networks) shows promise in learning complex control policies for diverse tasks in robot systems. Despite their great flexibility, the large neural networks for parameterizing control policies impose significant challenges. The learned neural control policies are often overcomplex and non-smooth, which can easily cause unexpected or diverging robot motions. Therefore, they often yield poor generalization performance in practice. To address this issue, we propose adVErsarially Regularized pOlicy learNIng guided by trajeCtory optimizAtion (VERONICA) for learning smooth control policies. Specifically, our proposed approach controls the smoothness (local Lipschitz continuity) of the neural control policies by stabilizing the output control with respect to the worst-case perturbation to the input state. Our experiments on robot manipulation show that our proposed approach not only improves the sample efficiency of neural policy learning but also enhances the robustness of the policy against various types of disturbances, including sensor noise, environmental uncertainty, and model mismatch.","Title: Geo-Context Aware Study of Vision-Based Autonomous Driving Models and Spatial Video Data\nYear: 2022\n\nAbstract: Vision-based deep learning (DL) methods have made great progress in learning autonomous driving models from large-scale crowd-sourced video datasets. They are trained to predict instantaneous driving behaviors from video data captured by on-vehicle cameras. In this paper, we develop a geo-context aware visualization system for the study of Autonomous Driving Model (ADM) predictions together with l...","Title: Reactive Locomotion Decision-Making and Robust Motion Planning for Real-Time Perturbation Recovery\nYear: 2022\n\nAbstract: In this paper, we examine the problem of push recovery for bipedal robot locomotion and present a reactive decision-making and robust planning framework for locomotion resilient to external perturbations. Rejecting perturbations is an essential capability of bipedal robots and has been widely studied in the locomotion literature. However, adversarial disturbances and aggressive turning can lead to negative lateral step width (i.e., crossed-leg scenarios) with unstable motions and self-collision risks. These motion planning problems are computationally difficult and have not been explored under a hierarchically integrated task and motion planning method. We explore a planning and decision-making framework that closely ties linear-temporal-logic-based reactive synthesis with trajectory optimization incorporating the robot's full-body dynamics, kinematics, and leg collision avoidance constraints. Between the high-level discrete symbolic decision-making and the low-level continuous motion planning, behavior trees serve as a reactive interface to handle perturbations occurring at any time of the locomotion process. Our experimental results show the efficacy of our method in generating resilient recovery behaviors in response to diverse perturbations from any direction with bounded magnitudes.","Title: Mass Estimation of a Moving Object Through Minimal Manipulation Interaction\nYear: 2021\n\nAbstract: In this paper, we study the problem of dynamic interaction between a robot and an unknown object (e.g., catching a ball, or handing off an object during locomotion). In particular, we propose a method for estimating the inertial parameters of an object during dynamic interaction, while minimally altering the trajectory of the object - a minimal interaction approach. Our method combines trajectory estimation (e.g., using standard methods from computer vision) with a model-based estimator that exploits the robot's known dynamic model. We first develop the method for a generalized three-dimensional problem, and then evaluate the method for the case of an object moving along a linear trajectory. We present experimental results obtained using a KUKA iiwa 7 interacting with rolling balls of varying mass. Our experiments demonstrate that the mass of the objects can be accurately estimated at the moment of impact when accurate object trajectory estimates are available, and that significant improvement can be obtained by incorporating force measurements at the contact point while following the object.","Title: Mediating Between Contact Feasibility and Robustness of Trajectory Optimization Through Chance Complementarity Constraints\nYear: 2021\n\nAbstract: As robots move from the laboratory into the real world, motion planning will need to account for model uncertainty and risk. For robot motions involving intermittent contact, planning for uncertainty in contact is especially important, as failure to successfully make and maintain contact can be catastrophic. Here, we model uncertainty in terrain geometry and friction characteristics, and combine a risk-sensitive objective with chance constraints to provide a trade-off between robustness to uncertainty and constraint satisfaction with an arbitrarily high feasibility guarantee. We evaluate our approach in two simple examples: a push-block system for benchmarking and a single-legged hopper. We demonstrate that chance constraints alone produce trajectories similar to those produced using strict complementarity constraints; however, when equipped with a robust objective, we show the chance constraints can mediate a trade-off between robustness to uncertainty and strict constraint satisfaction. Thus, our study may represent an important step towards reasoning about contact uncertainty in motion planning.","Title: A Low-Jitter Harmonic-Free All-Digital Delay-Locked Loop for Multi-Channel Vernier TDC\nYear: 2022\n\nAbstract: This paper presents a low jitter All-Digital Delay-Locked Loop (ADDLL) with fast lock time and process immunity. A coarse locking algorithm is proposed to prevent harmonic locking with just a small increase in hardware resources. In order to effectively solve the dithering phenomenon after locking, a replica delay line and a modified binary search algorithm with two modes were introduced in our ADDLL, which can significantly reduce the peak-to-peak jitter of the replica delay line. In addition, digital codes for a replica delay line can be conveniently applied to the delay line of multi-channel Vernier TDC while maintaining consistency between channels. The proposed ADDLL has been designed in 55 nm CMOS technology. In addition, the post-layout simulation results show that when operated at 1.2 V, the proposed ADDLL locks within 37 cycles and has a closed-loop characteristic, the peak-to-peak and root-mean-square jitter at 800 MHz are 6.5 ps and 1.18 ps, respectively. The active area is 0.024 mm(2) and the power consumption at 800 MHz is 6.92 mW. In order to verify the performance of the proposed ADDLL, an architecture of dual ADDLL is applied to Vernier TDC to stabilize the Vernier delay lines against the process, voltage, and temperature (PVT) variations. With a 600 MHz operating frequency, the TDC achieves a 10.7 ps resolution, and the proposed ADDLL can keep the resolution stable even if PVT varies.","Title: Safe Learning for Uncertainty-Aware Planning via Interval MDP Abstraction\nYear: 2022\n\nAbstract: We study the problem of refining satisfiability bounds for partially-known stochastic systems against planning specifications defined using syntactically co-safe Linear Temporal Logic (scLTL). We propose an abstraction-based approach that iteratively generates high-confidence Interval Markov Decision Process (IMDP) abstractions of the system from high-confidence bounds on the unknown component of the dynamics obtained via Gaussian process regression. In particular, we develop a synthesis strategy to sample the unknown dynamics by finding paths which avoid specification-violating states using a product IMDP. We further provide a heuristic to choose among various candidate paths to maximize the information gain. Finally, we propose an iterative algorithm to synthesize a satisfying control policy for the product IMDP system. We demonstrate our work with a case study on mobile robot navigation.","Title: Momentum-Aware Trajectory Optimization and Control for Agile Quadrupedal Locomotion\nYear: 2022\n\nAbstract: In this letter, we present a versatile hierarchical offline planning algorithm, along with an online control pipeline for agile quadrupedal locomotion. Our offline planner alternates between optimizing centroidal dynamics for a reduced-order model and whole-body trajectory optimization, with the aim of achieving dynamics consensus. Our novel momentum-inertia-aware centroidal optimization, which uses an equimomental ellipsoid parameterization, is able to generate highly acrobatic motions via \"inertia shaping\". Our whole-body optimization approach significantly improves upon the quality of standard DDP-based approaches by iteratively exploiting feedback from the centroidal level. For online control, we have developed a novel convex model predictive control scheme through a linear transformation of the full centroidal dynamics. Our controller can efficiently optimize for both contact forces and joint accelerations in single optimization, enabling more straightforward tracking for momentum-rich motions compared to existing quadrupedal MPC controllers. We demonstrate the capability and generality of our trajectory planner on four different dynamic maneuvers. We then present one hardware experiment on the MIT Mini Cheetah platform to demonstrate the performance of the entire planning and control pipeline on a twisting jump maneuver.","Title: Interactive Visualization and Capture of Geo-Coded Multimedia Data on Mobile Devices\nYear: 2021\n\nAbstract: In digital community applications, geo-coded multimedia data including spatial videos, speech, and geo-narratives are collected and utilized by community users and researchers from multiple fields. It is often preferred that these data can be captured, visualized, and explored directly on mobile phones and tablets interactively. In this paper, we present a Geo-Video Mobile Application (GVM App) that collects geo-coded multimedia data for experts to process and analyze over an interactive visual exploration. This mobile App integrates user interactivity, AI-based semantic image segmentation, and audio transcription for effective data extraction and utilization. Then visualization functions are designed to quickly present geographical, semantic, and street view visual information for knowledge discovery. The users of this tool can include community workers, teachers, and tourists, and also span across multiple social disciplines in digital humanity studies.","Title: Visual feature synthesis with semantic reconstructor for traditional and generalized zero-shot object classification\nYear: 2022\n\nAbstract: Zero-shot learning (ZSL) addresses the novel object recognition problem by leveraging semantic embedding to transfer knowledge from seen categories to unseen categories. Generative ZSL models synthesize the visual features of unseen classes and convert ZSL task into a classical supervised learning problem. These generative ZSL models are trained by using the seen classes. Although promising progress has been achieved in the ZSL and generalized zero-shot learning (GZSL) tasks. The existing approaches still suffer from a strong bias problem between unseen and seen classes, where unseen objects in the target domain tend to be recognized as seen classes in the source domain. To deal with the problem, we propose a novel named semantic consistent Wasserstein generative adversarial network (scWGAN), which uses a semantic reconstructor to reconstruct semantic embeddings from generated visual features by incorporating a novel Semantic Consistent Loss noted L rec. The Semantic Consistent Loss guides our proposed scWGAN to generate visual features that mirror the semantic relationships between seen and unseen classes. We also introduce a visual classifier to constrain visual feature generator. Extensive experiments show that the proposed approach is superior to previous state-of-the-art works under both traditional ZSL and challenging GZSL settings on six popular data sets AWA1, AWA2, CUB, APY, and SUN.","Title: Estimator-based iterative deviation-free residual generator for fault detection under random access protocol\nYear: 2022\n\nAbstract: This paper proposes an estimator-based iterative deviation-free residual generator (IDRG) for linear discrete-time stochastic systems. The communication between intelligent nodes and the remote estimator is realized by adopting a shared network. With the purpose of random access protocol (RAP) is utilized to schedule the data transmission process, according to which only one node at one instant is selected to get access to the communication network. The aim of the addressed problem is to detect the occurrence and disappearance of the faulty signal via utilizing the designed estimator. By solving an optimization problem subject to the deviation-free constraint, a novel batch estimator is firstly designed with finite response. Then, the IDRG is developed by extracting the residual signal out of the proposed estimator. By adopting the norm of the residual as the evaluation function, the Chebyshev inequalities are used to obtain the lower and upper stochastic thresholds. Finally, an illustrative example is given to demonstrate that the designed IDRG can detect the occurrence and disappearance of the faulty signals in a short transient stage, and is capable of reducing the false alarm rate in comparison to the benchmark Kalman filter residual generator (KFRG).","Title: Unbiasedness-constrained least squares state estimation for time-varying systems with missing measurements under round-robin protocol\nYear: 2022\n\nAbstract: In this paper, we present an unbiasedness-constrained approach to deal with the state estimation issue for a class of time-varying stochastic systems subject to missing measurements. The state estimates are generated from measurements collected by multiple sensing nodes whose information are transmitted via communication networks under scheduling of the Round-Robin protocol. The purpose of the addressed problem is to design an optimal state estimation algorithm in the sense of least mean square with an unknown initial condition in the existence of possible data missing. By resorting to the batch form technique, the optimal filter is proposed by minimising the estimation error covariance in the sense of matrix trace subject to the unbiasedness constraint. Then, a recursive computational algorithm is exploited for the optimal filter to facilitate practical realisation. Finally, simulations are carried out to demonstrate that the proposed method can be utilised to handle missing measurements in the multi-sensor systems when the initial states are unavailable, which outperforms the Kalman filter especially in the initial stage.","Title: A 7.4-Bit ENOB 600 MS/s FPGA-Based Online Calibrated Slope ADC without External Components\nYear: 2022\n\nAbstract: A slope analog-to-digital converter (ADC) amenable to be fully implemented on a digital field programmable gate array (FPGA) without requiring any external active or passive components is proposed in this paper. The amplitude information, encoded in the transition times of a standard LVDS differential input-driven by the analog input and by the reference slope generated by an FPGA output buffer-is retrieved by an FPGA time-to-digital converter. Along with the ADC, a new online calibration algorithm is developed to mitigate the influence of process, voltage, and temperature variations on its performance. Measurements on an ADC prototype reveal an analog input range from 0.3 V to 1.5 V, a least significant bit (LSB) of 2.6 mV, and an effective number of bits (ENOB) of 7.4-bit at 600 MS/s. The differential nonlinearity (DNL) is in the range between -0.78 and 0.70 LSB, and the integral nonlinearity (INL) is in the range from -0.72 to 0.78 LSB."],"string":"[\n \"Title: Spectral Image Decolorization\\nYear: 2010\\n\\nAbstract: We propose a novel method for decolorizing a color image to grayscale, which preserves the chromatic contrast to be lost if\\n using a simple luminance mapping. Unlike previous work, the conversion performs in spectral domain after applying Fourier\\n transforms on luminance and chromatic channels, and the resultant intensity is recovered from an inverse transform. Frequency\\n spectra inherently provide the magnitude of changes (i.e. contrast) among the channels, in all spatial scales. Consequently,\\n only simple arithmetic operations are needed to add chromatic differences to the final grayscale intensity, leading to realtime\\n computational speed. Moreover, users can flexibly control the decolorization effects by interactively adjusting visually-intuitive\\n parameters, in addition to our predefined values. The method has great potential to be incorporated in commercial software\\n and printer drivers due to its simplicity, speed and repeatability.\",\n \"Title: Voxels on Fire\\nYear: 2003\\n\\nAbstract: We introduce a method for the animation of fire propagation and the burning consumption of objects represented as volumetric data sets. Our method uses a volumetric fire propagation model based on an enhanced distance field. It can simulate the spreading of multiple fire fronts over a specified isosurface without actually having to create that isosurface. The distance field is generated from a specific shell volume that rapidly creates narrow spatial bands around the virtual surface of any given isovalue. The complete distance field is then obtained by propagation from the initial bands. At each step multiple fire fronts can evolve simultaneously on the volumetric object. The flames of the fire are constructed from streams of particles whose movement is regulated by a velocity field generated with the hardware-accelerated Lattice Boltzmann Model (LBM). The LBM provides a physically-based simulation of the air flow around the burning object. The object voxels and the splats associated with the flame particles are rendered in the same pipeline so that the volume data with its external and internal structures can be displayed along with the fire.\",\n \"Title: Discrete construction of order-k voronoi diagram\\nYear: 2010\\n\\nAbstract: The order-k Voronoi diagrams are difficult to construct because of their complicated structures. In traditional algorithm, production process was extremely complex. While discrete algorithm is only concerned with positions of generators, so it is effective for constructing Voronoi diagrams with complicated shapes of Voronoi polygons. It can be applied to order- k Voronoi diagram with any generators, and can get over most shortcomings of traditional algorithm. So it is more useful and effective. Model is constructed with discrete algorithm. And the application example shows that the algorithm is both simple and useful, and it is of high potential value in practice.\",\n \"Title: Discrete construction of power network voronoi diagram\\nYear: 2011\\n\\nAbstract: Power Network Voronoi diagrams are difficult to construct when the position relation of road segments are complicated. In traditional algorithm, The distance between objects must be calculated by selecting the minimum distance to their shared borders and doubling this value. When road segments cross or coincide with each other, production process will be extremely complex because we have to consider separately these parts. In this paper, we use discrete construction of network Voronoi diagrams. The algorithm can get over all kinds of shortcomings that we have just mentioned. So it is more useful and effective than the traditional ones. We also construct model according the algorithm. And the application example shows that the algorithm is both simple and useful, and it is of high potential value in practice.\",\n \"Title: Enhancing fluid animation with adaptive, controllable and intermittent turbulence\\nYear: 2010\\n\\nAbstract: This paper proposes a new scheme for enhancing fluid animation with controllable turbulence. An existing fluid simulation from ordinary fluid solvers is fluctuated by turbulent variation modeled as a random process of forcing. The variation is precomputed as a sequence of solenoidal noise vector fields directly in the spectral domain, which is fast and easy to implement. The spectral generation enables flexible vortex scale and spectrum control following a user prescribed energy spectrum, e.g. Kolmogorov's cascade theory, so that the fields provide fluctuations in subgrid scales and/or in preferred large octaves. The vector fields are employed as turbulence forces to agitate the existing flow, where they act as a stimulus of turbulence inside the framework of the Navier-Stokes equations, leading to natural integration and temporal consistency. The scheme also facilitates adaptive turbulent enhancement steered by various physical or user-defined properties, such as strain rate, vorticity, distance to objects and scalar density, in critical local regions. Furthermore, an important feature of turbulent fluid, intermittency is created by applying turbulence control during randomly selected temporal periods.\",\n \"Title: Incorporating stochastic turbulence in particle-based fluid simulation\\nYear: 2012\\n\\nAbstract: We propose a new fluid modeling technique aimed at incorporating stochastic turbulence into a widely used Lagrangian fluid solver, the Smoothed Particle Hydrodynamics (SPH) method. We add to each SPH particle a swirling probability to model its likelihood to act as a swirling incentive particle (SIP). Particles are selected as a SIP randomly based on the probability, and a SIP spins its neighboring particles to rotate around itself by applying rotational force. The force is computed from a swirling vorticity of the SIP. We model the production, development, and spreading of the swirling probability and vorticity among all SPH particles. The algorithm inherently implements preferred turbulence evolution including vortex aggregation and decay. The turbulent effects are non-repeating and easily controlled by animators. Our method is fully integrated with the SPH scheme with minimal extra memory usage, computational load, and programming efforts.\",\n \"Title: Discrete construction of Voronoi diagrams for cross generators\\nYear: 2010\\n\\nAbstract: Voronoi diagrams for cross generators are difficult to construct because of their complicated position relation. In traditional algorithm, when generators cross or coincide with each other, production process will be extremely complex because we have to consider separately these parts. In this paper, we use discrete construction of Voronoi diagrams. The algorithm can get over all kinds of shortcomings that we have just mentioned. So it is more useful and effective than the traditional ones. We also construct model according the algorithm. And the application example shows that the algorithm is both simple and useful, and it is of high potential value in practice.\",\n \"Title: Dispersion simulation and visualization for urban security\\nYear: 2004\\n\\nAbstract: We present a system for simulating and visualizing the propagation of dispersive contaminants with an application to urban security. In particular, we simulate airborne contaminant propagation in open environments characterised by sky-scrapers and deep urban canyons. Our approach is based on the multiple relaxation time lattice Boltzmann model (MRTLBM), which can efficiently handle complex boundary conditions such as buildings. In addition, we model thermal effects on the flow field using the hybrid thermal MRTLBM. Our approach can also accommodate readings from various sensors distributed in the environment and adapt the simulation accordingly. We accelerate the computation and efficiently render many buildings with small textures on the GPU. We render streamlines and the contaminant smoke with self-shadowing composited with the textured buildings.\",\n \"Title: Real-time visualization of streaming text with a force-based dynamic system.\\nYear: 2012\\n\\nAbstract: Streamit lets users explore visualizations of text streams without prior knowledge of the data. It incorporates incoming documents from a continuous source into an existing visualization context with automatic grouping and separation based on document similarities. A powerful user interface allows in-depth data analysis.\",\n \"Title: Visualizing clusters in parallel coordinates for visual knowledge discovery\\nYear: 2012\\n\\nAbstract: Parallel coordinates is frequently used to visualize multi-dimensional data. In this paper, we are interested in how to effectively visualize clusters of multi-dimensional data in parallel coordinates for the purpose of facilitating knowledge discovery. In particular, we would like to efficiently find a good order of coordinates for different emphases on visual knowledge discovery. To solve this problem, we link it to the metric-space Hamiltonian path problem by defining the cost between every pair of coordinates as the number of inter-cluster or intra-cluster crossings. This definition connects to various efficient solutions and leads to very fast algorithms. In addition, to better observe cluster interactions, we also propose to shape clusters smoothly by an energy reduction model which provides both macro and micro view of clusters.\",\n \"Title: Robust stability criterion for discrete-time uncertain Markovian jumping neural networks with defective statistics of modes transitions.\\nYear: 2011\\n\\nAbstract: This brief is concerned with the robust stability problem for a class of discrete-time uncertain Markovian jumping neural networks with defective statistics of modes transitions. The parameter uncertainties are considered to be norm-bounded, and the stochastic perturbations are described in terms of Brownian motion. Defective statistics means that the transition probabilities of the multimode neural networks are not exactly known, as assumed usually. The scenario is more practical, and such defective transition probabilities comprise three types: known, uncertain, and unknown. By invoking the property of the transition probability matrix and the convexity of uncertain domains, a sufficient stability criterion for the underlying system is derived. Furthermore, a monotonicity is observed concerning the maximum value of a given scalar, which bounds the stochastic perturbation that the system can tolerate as the level of the defectiveness varies. Numerical examples are given to verify the effectiveness of the developed results.\",\n \"Title: GPU accelerated lattice Boltzmann simulation for rotational turbulence\\nYear: 2014\\n\\nAbstract: In this work, we numerically study decaying isotropic turbulence in periodic cubes with frame rotation using the lattice Boltzmann method (LBM) and present the results of rotation effects on turbulence. The implementation of LBM is on a GPU (Graphic Processing Unit) platform using CUDA (Compute Unified Device Architecture). Through the accelerated GPU-LBM simulation, we look into various effects of frame rotation on turbulence. It has been observed that rotation slows down the decay of kinetic energy and enstrophy. Rotation also breaks isotropy and induces vortex tubes in the direction of frame rotation. Characteristics related to velocity and its derivatives have been studied with and without rotation. Without rotation, the kinetic energy and enstrophy decay follow -10/7 and -17/7 scaling respectively whereas in the presence of rotation with the relatively small Rossby number (large rotation intensity), the energy decay slows down to -5/21 scaling when the initial isotropic turbulence energy spectrum is scaled to k^4. These scalings with and without rotation are in quantitative agreements with the predictions from Kolmogorov hypotheses respectively. The skewness and kurtosis are seen more fluctuating in rotational turbulence, which agrees with the results from NS-based computation. Using this accelerated and validated GPU-LBM computation tool, we are further studying the inverse energy transfer behavior with and without rotation aiming to quantify the effects of rotation on the inverse energy transfer to reveal underlying physics of a particular stage of the turbulence development. The results will be presented in near future.\",\n \"Title: Gpu-Accelerated Surface Denoising And Morphing With Lattice Boltzmann Scheme\\nYear: 2008\\n\\nAbstract: In this paper, we introduce a parallel numerical scheme, the lattice Boltzmann method, to shape modeling applications. The motivation of using this originally-designed fluid dynamics solver in surface modeling is its simplicity, locality, parallelism from the cellular-automata-originated updating rules, which can directly be mapped onto modem graphics hardware. A surface is implicitly represented by the signed distance field. The distances are then used in a modified LBM scheme as its computing primitive, instead of the densities in traditional LBM. The scheme can simulate curvature motions to smooth the surface with a diffusion process. Furthermore, an initial value level set method can be implemented for surface morphing. The distance difference between a morphing surface and a target surface defines the speed function of the evolving level sets, and is used as the driving force in the LBM. Our GPU-accelerated LBM algorithm has achieved outstanding performance for the denoising and morphing examples. It has the great potential to be further applied as a general GPU computing framework to many other solid and shape modeling applications.\",\n \"Title: Spatial Density Voronoi Diagram And Construction\\nYear: 2012\\n\\nAbstract: To fill a theory gap of Voronoi diagrams that there have been no reports of extended diagrams in spatial density so far. A new concept of spatial density Voronoi diagram was proposed. An important property was presented and proven. And a construction algorithm was presented. Spatial density can be used to indicate factors related to density such as conveyance and the traffic conditions. Some properties of spatial density Voronoi diagram were also introduced. In accordance with discrete construction method, achieved the construction of spatial density Voronoi diagram. Spatial density Voronoi diagram is a developed Voronoi diagram, and planar ordinary Voronoi diagram can be regarded as its special cases. It both perfected the theory about Voronoi diagrams, and extended the range of applications of Voronoi diagrams.\",\n \"Title: Melting and flowing in multiphase environment\\nYear: 2006\\n\\nAbstract: This paper presents a method to simulate the melting and flowing phenomena with different materials in multiple phases. In such a multiphase environment, solid objects are melted because of heating and the melted liquid flows while interacting with the ambient air flow. Our simulation is based on a modified lattice Boltzmann method (LBM), where the fluid dynamics of the air flow and the melted liquid is modeled within a common lattice framework. Therefore, no particular front tracking methods are required for the liquid–air interface. The liquid–solid and air–solid interfaces are implemented as curved boundaries in the LBM, which can accommodate arbitrarily shaped solid objects. Heat transfer is incorporated with a finite difference discretization of a standard diffusion–advection equation simulating the temperature evolution. The temperature and body forces (gravity and surface tension) are easily applied by adopting a new version of the LBM: multiple-relaxation-time LBM (MRTLBM). The melting and flowing behavior is controlled by the heat source, the viscosity and the body forces. All the numerical computations in our method are local and parallelizable, therefore, interactive speed is achieved by hardware acceleration on the contemporary graphics hardware (GPU).\",\n \"Title: Lattice Boltzmann based PDE solver on the GPU\\nYear: 2008\\n\\nAbstract: In this paper, we propose a hardware-accelerated PDE (partial differential equation) solver based on the lattice Boltzmann model (LBM). The LBM is initially designed to solve fluid dynamics by constructing simplified microscopic kinetic models. As an explicit numerical scheme with only local operations, it has the advantage of being easy to implement and especially suitable for graphics hardware (GPU) acceleration. Beyond the Navier–Stokes equation of fluid mechanics, a typical LBM can be modified to solve the parabolic diffusion equation, which is further used to solve the elliptic Laplace and Poisson equations with a diffusion process. These PDEs are widely used in modeling and manipulating images, surfaces and volumetric data sets. Therefore, the LBM scheme can be used as an GPU-based numerical solver to provide a fast and convenient alternative to traditional implicit iterative solvers. We apply this method to several examples in volume smoothing, surface fairing and image editing, achieving outstanding performance on contemporary graphics hardware. It has the great potential to be used as a general GPU computing framework for efficiently solving PDEs in image processing, computer graphics and visualization.\",\n \"Title: Visual simulation of thermal fluid dynamics in a pressurized water reactor\\nYear: 2009\\n\\nAbstract: We present a simulation and visualization system for a critical application—analysis of the thermal fluid dynamics inside a pressurized water reactor of a nuclear power plant when cold water is injected into the reactor vessel. We employ a hybrid thermal lattice Boltzmann method (HTLBM), which has the advantages of ease of parallelization and ease of handling complex simulation boundaries. For efficient computation and storage of the irregular-shaped simulation domain, we classify the domain into nonempty and empty cells and apply a novel packing technique to organize the nonempty cells. This method is implemented on a GPU cluster for acceleration. We demonstrate the formation of cold-water plumes in the reactor vessel. A set of interactive visualization tools, such as side-view slices, 3D volume rendering, thermal layers rendering, and panorama rendering, are provided to collectively visualize the structure and dynamics of the temperature field in the vessel. To the best of our knowledge, this is the first system that combines 3D simulation and visualization for analyzing thermal shock risk in a pressurized water reactor.\",\n \"Title: Pattern-guided smoke animation with lagrangian coherent structure\\nYear: 2011\\n\\nAbstract: Fluid animation practitioners face great challenges from the complexity of flow dynamics and the high cost of numerical simulation. A major hindrance is the uncertainty of fluid behavior after simulation resolution increases and extra turbulent effects are added. In this paper, we propose to regulate fluid animations with predesigned flow patterns. Animators can design their desired fluid behavior with fast, low-cost simulations. Flow patterns are then extracted from the results by the Lagrangian Coherent Structure (LCS) that represents major flow skeleton. Therefore, the final high-quality animation is confined towards the designed behavior by applying the patterns to drive high-resolution and turbulent simulations. The pattern regulation is easily computed and achieves controllable variance in the output. The method makes it easy to design special fluid effects, which increases the usability and scalability of various advanced fluid modeling technologies.\",\n \"Title: Image matching by fast random sample consensus\\nYear: 2013\\n\\nAbstract: The traditional Random Sample Consensus (RANSAC) algorithm tends to exhibit deficiencies when faced with large amounts of data. In this paper, we present an algorithm called fast Random Sample Consensus (abbr. F-RANSAC) which is able to improve computation efficiency and robustness. We first use the nearest neighbor algorithm to retrieve candidate match points with ranked matching scores. We then construct representative data sets by using a minimal number of optimal matches. Finally, the target homographic matrix is fitted based on the representative data set. Experiments on affine covariant region datasets demonstrate that F-RANSAC significantly enhances computation efficiency(3 times to 10 times) and slightly improves accuracy.\",\n \"Title: Active Suspension Control With Frequency Band Constraints and Actuator Input Delay\\nYear: 2012\\n\\nAbstract: This paper investigates the problem of vehicle active suspension control with frequency band constraints and actuator input delay. First, the mathematical model of suspension systems is established, and the problem of suspension control with finite-frequency constraints is formulated to match the characteristics of the human body. Then, the finite-frequency method is developed to deal with the problem of suspension control with actuator input delay, based on the generalized Kalman-Yakubovich-Popov lemma. Compared with the traditional entire-frequency approach for active suspension systems, the finite-frequency approach proposed in this paper achieves better disturbance attenuation performance for the chosen frequency range while the constraints required by real situation are guaranteed in the controller design. The effectiveness and merits of the proposed method are verified by a number of simulations with several types of road disturbances.\",\n \"Title: DYNATOPS: a dynamic topic-based publish/subscribe architecture\\nYear: 2013\\n\\nAbstract: Emerging societal scale notification applications call for a system that is able to efficiently support simple, yet changing subscriptions for a very large number of users. In this paper we propose DYNATOPS, a dynamic topic-based pub/sub architecture that provides efficient scalable societal scale event notifications for dynamic subscriptions via distributed broker networks. In DYNATOPS, users are moderately repositioned on brokers and brokers are moderately repositioned on the overlay structure for efficient event notifications, to adapt to the publications and subscription dynamics. In contrast to existing self-organized techniques, the broker network reconfiguration in DYNATOPS is executed in a planned manner utilizing a cost-driven reconfiguration process. With extensive experiments, we observe that under highly dynamic subscriptions DYNATOPS can still maintain an efficient dissemination structure that provides 30% less notification delay and overhead in general, and a reconfiguration cost reduction of 80% as compared to other state-of-the-art systems.\",\n \"Title: GSFord: Towards a Reliable Geo-social Notification System\\nYear: 2012\\n\\nAbstract: The eventual goal of any notification system is to deliver appropriate messages to all relevant recipients with very high reliability in a timely manner. In particular, we focus on notification in extreme situations (e.g. disasters) where geographically correlated failures hinder the ability to reach recipients inside the corresponding failed region. In this paper, we present GSFord, a reliable geo-social notification system that is aware of (a) the geographies in which the message needs to be disseminated and (b) the social network characteristics of the intended recipient, in order to maximize/increase the coverage and reliability. GSFord builds robust geo-aware P2P overlays to provide efficient location-based message delivery and reliable storage of geo-social information of recipients. When an event occurs, GSFord is able to efficiently deliver the message to recipients who are either (a) located in the event area or (b) socially correlated to the event (e.g. relatives/friends of those who are impacted by an event). Furthermore, GSFord leverages the geo-social information to trigger a social diffusion process, which operates through out-of band channels such as phone calls and human contacts, in order to reach recipients which are isolated in the failed region. Through extensive evaluations, we show that GSFord is reliable, the social diffusion process enhanced by GSFord reaches up to 99.9% of desired recipients even under massive geographically correlated regional failures. We also show that GSFord is efficient even under skewed distribution of user populations.\",\n \"Title: Modeling path duration time in dynamic convergecast network\\nYear: 2013\\n\\nAbstract: Estimating communication latency is challenging in dynamic settings, e.g mobile applications where the source and/or destination of the communication can move arbitrarily. In this paper, we explore a many-to-one communication pattern, called convergecast, where mobile sensors report their sensed values to one or more servers (data sinks) in a periodic or queried manner. Such ”convergecast” communication is becoming increasingly relevant in sensor monitoring and pervasive sensing applications. An important aspect of enabling accurate collection is to ensure small delays in the collection process. The path duration, i.e time between when a path from sensor to source is established and when it gets disrupted, is a key factor that affects end-to-end delay; much of the existing work on this topic is in the context of MANETs. We propose and evaluate a probabilistic model in convergecast to capture path duration times given models of the network/transmission, the scale of the network and mobility of network elements. We validate our model through simulations and verify that the proposed model can provide a reasonable representation for end-to-end delays in the convergecast network. Pervasive sensor networks of the future are likely to encompass multiple access technologies with varying network properties and transmission characteristics. The ability to model end-to-end network properties (such as path duration) can assist in improved utilization in such pervasive multinetworks.\",\n \"Title: Visual simulation of heat shimmering and mirage.\\nYear: 2007\\n\\nAbstract: We provide a physically-based framework for simulating the natural phenomena related to heat interaction between objects and the surrounding air. We introduce a heat transfer model between the heat source objects and the ambient flow environment, which includes conduction, convection, and radiation. The heat distribution of the objects is represented by a novel temperature texture. We simulate the thermal flow dynamics that models the air flow interacting with the heat by a hybrid thermal lattice Boltzmann model (HTLBM). The computational approach couples a multiple-relaxation-time LBM (MRTLBM) with a finite difference discretization of a standard advection-diffusion equation for temperature. In heat shimmering and mirage, the changes in the index of refraction of the surrounding air are attributed to temperature variation. A nonlinear ray tracing method is used for rendering. Interactive performance is achieved by accelerating the computation of both the MRTLBM and the heat transfer, as well as the rendering on contemporary graphics hardware (GPU).\",\n \"Title: Optimum location on fuzzy clustering method\\nYear: 2010\\n\\nAbstract: In this paper, fuzzy cluster method is presented to solve traditional optimum location problem. We consider objects of users as some discrete points. Points are classified by using fuzzy clustering method on condition of large number of them, because the distance between points can be tested by the similarity of axis of the given points. We discuss the single-objective location problem, and construct a model according to realistic situation. The method can also be used in the multi-objective location problem.\",\n \"Title: Lattice-based flow field modeling.\\nYear: 2004\\n\\nAbstract: We present an approach for simulating the natural dynamics that emerge from the interaction between a flow field and immersed objects. We model the flow field using the Lattice Boltzmann Model (LBM) with boundary conditions appropriate for moving objects and accelerate the computation on commodity graphics hardware (GPU) to achieve real-time performance. The boundary conditions mediate the exchange of momentum between the flow field and the moving objects resulting in forces exerted by the flow on the objects as well as the back-coupling on the flow. We demonstrate our approach using soap bubbles and a feather. The soap bubbles illustrate Fresnel reflection, reveal the dynamics of the unseen flow field in which they travel, and display spherical harmonics in their undulations. Our simulation allows the user to directly interact with the flow field to influence the dynamics in real time. The free feather flutters and gyrates in response to lift and drag forces created by its motion relative to the flow. Vortices are created as the free feather falls in an otherwise quiescent flow.\",\n \"Title: PIWI: visually exploring graphs based on their community structure.\\nYear: 2013\\n\\nAbstract: Community structure is an important characteristic of many real networks, which shows high concentrations of edges within special groups of vertices and low concentrations between these groups. Community related graph analysis, such as discovering relationships among communities, identifying attribute-structure relationships, and selecting a large number of vertices with desired structural features and attributes, are common tasks in knowledge discovery in such networks. The clutter and the lack of interactivity often hinder efforts to apply traditional graph visualization techniques in these tasks. In this paper, we propose PIWI, a novel graph visual analytics approach to these tasks. Instead of using Node-Link Diagrams (NLDs), PIWI provides coordinated, uncluttered visualizations, and novel interactions based on graph community structure. The novel features, applicability, and limitations of this new technique have been discussed in detail. A set of case studies and preliminary user studies have been conducted with real graphs containing thousands of vertices, which provide supportive evidence about the usefulness of PIWI in community related tasks.\",\n \"Title: Stochastic modeling of light-weight floating objects\\nYear: 2011\\n\\nAbstract: Light-weight objects floating inside a flow play a significant role in the liveliness of our world (e.g., leaves, dust, snowflakes, bubbles). They follow the flow and show complex and chaotic motion. First, animators usually add simple random noise to the streaming path. However, this method yields low-quality floating behavior since the random noise does not take into account the spatial and temporal distribution of underlying flow turbulence. For example, obstacle-induced oscillation cannot be easily created as a major source of the unique motion. Second, floating objects can be passively advected by flow velocities from physically-based simulation. A critical challenge is that modeling the important jiggling motion requires turbulent flow field, which is hard to achieve by direct numerical simulation (DNS) due to limited computational resources and numerical dissipation. This situation deteriorates severely when realtime performance and interactivity are demanded in a 3D gaming environment. Moreover, the floating motion has intrinsic stochastic nature, i.e., the repeated executions result in nonidentical dynamics, which is not achievable with deterministic simulation. Third, adding noise to fluid solvers can introduce chaotic flow velocities (e.g. [Pfaff et al. 2010]). In an approach, special Langevin particles affect fluid solver with forces [Chen et al. 2011]. However, such methods rely on DNS and apply chaotic addition to the whole fluid domain, which is inefficient in handling a group of floating objects inside.\",\n \"Title: Flow simulation with locally-refined LBM\\nYear: 2007\\n\\nAbstract: We simulate 3D fluid flow by a locally-refined lattice Boltzmann method (LBM) on graphics hardware. A low resolution LBM simulation running on a coarse grid models global flow behavior of the entire domain with low consumption of computational resources. For regions of interest where small visual details are desired, LBM simulations are performed on fine grids, which are separate grids superposed on the coarse one. The flow properties on boundaries of the fine grids are determined by the global simulation on the coarse grid. Thus, the locally refined fine-grid simulations follow the global fluid behavior, and model the desired small-scale and turbulent flow motion with their denser numerical discretization. A fine grid can be initiated and terminated at any time while the global simulation is running. It can also move inside the domain with a moving object to capture small-scale vortices caused by the object. Besides the performance improvement due to the adaptive simulation, the locally-refined LBM is suitable for acceleration on contemporary graphics hardware (GPU), since it involves only local and linear computations. Therefore, our approach achieves fast and adaptive 3D flow simulation for computer games and other interactive applications.\",\n \"Title: Line–Line Fault Analysis and Protection Challenges in Solar Photovoltaic Arrays\\nYear: 2013\\n\\nAbstract: Fault analysis in solar photovoltaic (PV) arrays is a fundamental task to protect PV modules from damage and to eliminate risks of safety hazards. This paper focuses on line-line faults in PV arrays that may be caused by short-circuit faults or double ground faults. The effect on fault current from a maximum-power-point tracking of a PV inverter is discussed and shown to, at times, prevent overcurrent protection devices (OCPDs) to operate properly. Furthermore, fault behavior of PV arrays is highly related to the fault location, fault impedance, irradiance level, and use of blocking diodes. Particularly, this paper examines the challenges to OCPD in a PV array brought by unique faults: One is a fault that occurs under low-irradiance conditions, and the other is a fault that occurs at night and evolves during “night-to-day” transition. In both circumstances, the faults might remain hidden in the PV system, no matter how irradiance changes afterward. These unique faults may subsequently lead to unexpected safety hazards, reduced system efficiency, and reduced reliability. A small-scale experimental PV system has been developed to further validate the conclusions.\",\n \"Title: Parallel 3D Image Segmentation of Large Data Sets on a GPU Cluster\\nYear: 2009\\n\\nAbstract: In this paper, we propose an inherent parallel scheme for 3D image segmentation of large volume data on a GPU cluster. This method originates from an extended Lattice Boltzmann Model (LBM), and provides a new numerical solution for solving the level set equation. As a local, explicit and parallel scheme, our method lends itself to several favorable features: (1) Very easy to implement with the core program only requiring a few lines of code; (2) Implicit computation of curvatures; (3) Flexible control of generating smooth segmentation results; (4) Strong amenability to parallel computing, especially on low-cost, powerful graphics hardware (GPU). The parallel computational scheme is well suited for cluster computing, leading to a good solution for segmenting very large data sets.\",\n \"Title: Tile-Based Parallel Coordinates And Its Application In Financial Visualization\\nYear: 2010\\n\\nAbstract: Parallel coordinates technique has been widely used in information visualization applications and it has achieved great success in visualizing multivariate data and perceiving their trends. Nevertheless, visual clutter usually weakens or even diminishes its ability when the data size increases. In this paper, we first propose a tile-based parallel coordinates, where the plotting area is divided into rectangular tiles. Each tile stores an intersection density that counts the total number of polylines intersecting with that tile. Consequently, the intersection density is mapped to optical attributes, such as color and opacity, by interactive transfer functions. The method visualizes the polylines efficiently and informatively in accordance with the density distribution, and thus, reduces visual cluttering and promotes knowledge discovery. The interactivity of our method allows the user to instantaneously manipulate the tiles distribution and the transfer functions. Specifically, the classic parallel coordinates rendering is a special case of our method when each tile represents only one pixel. A case study on a real world data set, U. S. stock mutual fund data of year 2006, is presented to show the capability of our method in visually analyzing financial data. The presented visual analysis is conducted by an expert in the domain of finance. Our method gains the support from professionals in the finance field, they embrace it as a potential investment analysis tool for mutual fund managers, financial planners, and investors.\",\n \"Title: A visual analytics approach to exploring protein flexibility subspaces\\nYear: 2013\\n\\nAbstract: Understanding what causes proteins to change shape and how the resulting shape influences function will expedite the design of more narrowly focused drugs and therapies. Shape alterations are often the result of flexibility changes in a set of localized neighborhoods that may or may not act in concert. Computational models have been developed to predict flexibility changes under varying empirical parameters. In this paper, we tackle a significant challenge facing scientists when analyzing outputs of a computational model, namely how to identify, examine, compare, and group interesting neighborhoods of proteins under different parameter sets. This is a difficult task since comparisons over protein subunits that comprise diverse neighborhoods are often too complex to characterize with a simple metric and too numerous to analyze manually. Here, we present a series of novel visual analytics approaches toward addressing this task. User scenarios illustrate the utility of these approaches and feedback from domain experts confirms their effectiveness.\",\n \"Title: Langevin Particle: A Self-Adaptive Lagrangian Primitive for Flow Simulation Enhancement\\nYear: 2011\\n\\nAbstract: We develop a new Lagrangian primitive, named Langevin particle, to incorporate turbulent flow details in fluid simulation. A group of the particles are distributed inside the simulation domain based on a turbulence energy model with turbulence viscosity. A particle in particular moves obeying the generalized Langevin equation, a well known stochastic differential equation that describes the particle's motion as a random Markov process. The resultant particle trajectory shows self-adapted fluctuation in accordance to the turbulence energy, while following the global flow dynamics. We then feed back Langevin forces to the simulation based on the stochastic trajectory, which drive the flow with necessary turbulence. The new hybrid flow simulation method features nonrestricted particle evolution requiring minimal extra manipulation after initiation. The flow turbulence is easily controlled and the total computational overhead of enhancement is minimal based on typical fluid solvers.\",\n \"Title: Using Entropy-Related Measures in Categorical Data Visualization.\\nYear: 2014\\n\\nAbstract: A wide variety of real-world applications generate massive high dimensional categorical datasets. These datasets contain categorical variables whose values comprise a set of discrete categories. Visually exploring these datasets for insights is of great interest and importance. However, their discrete nature often confounds the direct application of existing multidimensional visualization techniques. We use measures of entropy, mutual information, and joint entropy as a means of harnessing this discreteness to generate more effective visualizations. We conduct user studies to assess the benefits in visual knowledge discovery.\",\n \"Title: Asynchronous Filtering of Discrete-Time Switched Linear Systems With Average Dwell Time\\nYear: 2011\\n\\nAbstract: Switched dynamical systems can be found in many practical electronic circuits, such as various kinds of power converters, chaos generators, etc. This paper is concerned with the filter design problem for a class of switched system with average dwell time switching. Mode-dependent full-order filters are designed taking a more practical phenomenon, the asynchronous switching into account, where “asynchronous” means that the switching of the filters to be designed has a lag to the switching of the system modes. New results on the stability and l2-gain analyses for the systems are first given where the Lyapunov-like functions during the running time of subsystems are allowed to increase. In light of the proposed Lyapunov-like functions, the desired mode-dependent filters can be designed in that the unmatched filters are allowed to perform in the interval of the asynchronous switching before the matched ones are applied. In H∞ sense, the problem of asynchronous filtering for the underlying systems in linear cases is formulated and the conditions of the existence of admissible asynchronous filters are obtained. Two examples are provided to show the potential of the developed results.\",\n \"Title: Visual Analysis of Mutual Fund Performance\\nYear: 2009\\n\\nAbstract: Mutual funds are probably the most important investment instruments for investors. Their performance is mainly affected by their characteristics, such as asset size, turnover and fee structure. It is thus of the investors' highest priorities to understand the relation between fund performance and these properties. Typically, financial researchers use the linear regression technique to statistically assess the relation from massive fund performance data. Unfortunately, the prevailing methods may be confounded by the existence of on-linearity and outliers, and give conflicting conclusions. In this paper, we propose a visualization-based method to improve the mutual fund analysis, where a new visual analytical tool, the density-based distribution map, is applied. The new visual representations greatly help to understand the critical relations, reveal the deficiency of current analytical algorithms,and support mutual funds selection. The tool is used to perform an expert financial analysis, and establish a fund selection strategy from a real-world database of the US stock funds. Our method gains the admiration and support from professionals in the finance field, they embrace it as a potential investment analysis tool for mutual fund managers, financial planners, and investors.\",\n \"Title: Visual analysis for mutual fund performance\\nYear: 2008\\n\\nAbstract: Mutual funds are one of the most important investment instruments available. However, choosing among mutual funds is not an easy task because they vary in many different dimensions, such as asset size, turnover and fee structure, and these characteristics may affect fund returns. It is thus important to understand the relation between fund performance and these properties. In this work, we use a new visual analytical tool, the density-based distribution map, to assist in this task. By visualizing various important fund characteristics from a real-world database of the US stock funds, our new visual representations greatly help understand the relation between fund characteristics and returns.\",\n \"Title: Visualizing Hidden Themes of Taxi Movement with Semantic Transformation\\nYear: 2014\\n\\nAbstract: A new methodology is developed to discover and analyze the hidden knowledge of massive taxi trajectory data within a city. This approach creatively transforms the geographic coordinates (i.e. latitude and longitude) to street names reflecting contextual semantic information. Consequently, the movement of each taxi is studied as a document consisting of the taxi traversed street names, which enables semantic analysis of massive taxi data sets as document corpora. Hidden themes, namely taxi topics, are identified through textual topic modeling techniques. The taxi topics reflect urban mobility patterns and trends, which are displayed and analyzed through a visual analytics system. The system integrates interactive visualization tools, including taxi topic maps, topic routes, street clouds and parallel coordinates, to visualize the probability-based topical information. Urban planners, administration, travelers, and drivers can conduct their various knowledge discovery tasks with direct semantic and visual assists. The effectiveness of this approach is illustrated by case studies using a large taxi trajectory data set acquired from 21, 360 taxis in a city.\",\n \"Title: A Three Dimensional Foot Placement Planner For Locomotion In Very Rough Terrains\\nYear: 2012\\n\\nAbstract: Maneuvering through 3D structures nimbly is pivotal to the advancement of legged locomotion. However, few methods have been developed that can generate 3D gaits in those terrains and fewer if none can be generalized to control dynamic maneuvers. In this study, foot placement planning for dynamic locomotion traversing irregular terrains is explored in three dimensional space. Given boundary values of the center of mass' apexes during the gait, sagittal and lateral phase-plane trajectories are predicted based on multi-contact and inverted pendulum dynamics. To deal with the nonlinear dynamics of the contact motions and their dimensionality, we plan a geometric surface of motion beforehand and rely on numerical integration to solve the models. In particular, we combine multi-contact and prismatic inverted pendulum models to resolve feet transitions between steps, allowing to produce trajectory patterns similar to those observed in human locomotion. Our contributions lay in the following points: (1) the introduction of non planar surfaces to characterize the center of mass' geometric behavior; (2) an automatic gait planner that simultaneously resolves sagittal and lateral feet placements; (3) the introduction of multi-contact dynamics to smoothly transition between steps in the rough terrains.\",\n \"Title: The magic volume lens: an interactive focus+context technique for volume rendering\\nYear: 2005\\n\\nAbstract: The size and resolution of volume datasets in science and medicine are increasing at a rate much greater than the resolution of the screens used to view them. This limits the amount of data that can be viewed simultaneously, potentially leading to a loss of overall context of the data when the user views or zooms into a particular area of interest. We propose a focus+context framework that uses various standard and advanced magnification lens rendering techniques to magnify the features of interest, while compressing the remaining volume regions without clipping them away completely. Some of these lenses can be interactively configured by the user to specify the desired magnification patterns, while others are feature-adaptive. All our lenses are accelerated on the GPU. They allow the user to interactively manage the available screen area, dedicating more area to the more resolution-important features.\",\n \"Title: STREAMIT: Dynamic visualization and interactive exploration of text streams\\nYear: 2011\\n\\nAbstract: Text streams demand an effective, interactive, and on-the-fly method to explore the dynamic and massive data sets, and meanwhile extract valuable information for visual analysis. In this paper, we propose such an interactive visualization system that enables users to explore streaming-in text documents without prior knowledge of the data. The system can constantly incorporate incoming documents from a continuous source into existing visualization context, which is \\\"physically\\\" achieved by minimizing a potential energy defined from similarities between documents. Unlike most existing methods, our system uses dynamic keyword vectors to incorporate newly-introduced keywords from data streams. Furthermore, we propose a special keyword importance that makes it possible for users to adjust the similarity on-the-fly, and hence achieve their preferred visual effects in accordance to varying interests, which also helps to identify hot spots and outliers. We optimize the system performance through a similarity grid and with parallel implementation on graphics hardware (GPU), which achieves instantaneous animated visualization even for a very large data collection. Moreover, our system implements a powerful user interface enabling various user interactions for in-depth data analysis. Experiments and case studies are presented to illustrate our dynamic system for text stream exploration.\",\n \"Title: Distance Field Transform with an Adaptive Iteration Method\\nYear: 2009\\n\\nAbstract: We propose a novel distance field transform method based on an iterative method adaptively performed on an evolving active band. Our method utilizes a narrow band to store active grid points being computed. Unlike the conventional fast marching method, we do not maintain a priority queue, and instead, perform iterative computing inside the band. This new algorithm alleviates the programming complexity and the data-structure (e.g. a heap) maintenance overhead, and leads to a parallel amenable computational process. During the active band propagating from a starting boundary layer, each grid point stays in the band for a lifespan time, which is determined by analyzing the particular geometric property of the grid structure. In this way, we find the Face-Centered Cubic (FCC) grid is a good 3D structure for distance transform. We further develop a multiple-segment method for the band propagation, achieving the computational complexity of O(m . N) with a segment-related constant m.\",\n \"Title: A Bistatic SAR Image Intensity Model for the Composite Ship–Ocean Scene\\nYear: 2015\\n\\nAbstract: Based on the scattering mechanisms of multipath, a bistatic synthetic aperture radar (Bis-SAR) image intensity model for the composite ship-ocean (or other metallic targets with ocean) scene is developed in this paper through reasonably dealing with the path lengths of transmitter and receiver to the ship target. To get a Bis-SAR image intensity model for the composite ship-ocean scene, the Bis-SAR image intensity distribution for the ocean surface is analyzed, and the facet scattering model is used to give the individual returns from separate facets. In addition, the influence of velocity bunching (VB) modulation of long ocean waves on the distribution of radar cross section is also discussed. Finally, Bis-SAR imagery simulations of ocean wave and the composite ship-ocean scene are illustrated, and the results show that the proposed Bis-SAR image intensity model can be reasonable and the interaction effects between the ship and sea surface can make significant contributions to the Bis-SAR intensity.\",\n \"Title: Assessing Whole-Body Operational Space Control in a Point-Foot Series Elastic Biped: Balance on Split Terrain and Undirected Walking.\\nYear: 2015\\n\\nAbstract: In this paper we present advancements in control and trajectory generation for agile behavior in bipedal robots. We demonstrate that Whole-Body Operational Space Control (WBOSC), developed a few years ago, is well suited for achieving two types of agile behaviors, namely, balancing on a high pitch split terrain and achieving undirected walking on flat terrain. The work presented here is the first implementation of WBOSC on a biped robot, and more specifically a biped robot with series elastic actuators. We present and analyze a new algorithm that dynamically balances point foot robots by choosing footstep placements. Dealing with the naturally unstable dynamics of these type of systems is a difficult problem that requires both the controller and the trajectory generation algorithm to operate quickly and efficiently. We put forth a comprehensive development and integration effort: the design and construction of the biped system and experimental infrastructure, a customization of WBOSC for the agile behaviors, and new trajectory generation algorithms. Using this custom built controller, we conduct, for first time, an experiment in which a biped robot balances in a high pitch split terrain, demonstrating our ability to precisely regulate internal forces using force sensing feedback techniques. Finally, we demonstrate the stabilizing capabilities of our online trajectory generation algorithm in the physics-based simulator and through physical experiments with a planarized locomotion setup.\",\n \"Title: A visual reasoning approach for data-driven transport assessment on urban roads\\nYear: 2014\\n\\nAbstract: Transport assessment plays a vital role in urban planning and traffic control, which are influenced by multi-faceted traffic factors involving road infrastructure and traffic flow. Conventional solutions can hardly meet the requirements and expectations of domain experts. In this paper we present a data-driven solution by leveraging a visual analysis system to evaluate the real traffic situations based on taxi trajectory data. A sketch-based visual interface is designed to support dynamic query and visual reasoning of traffic situations within multiple coordinated views. In particular, we propose a novel road-based query model for analysts to interactively conduct evaluation tasks. This model is supported by a bi-directional hash structure, TripHash, which enables real-time responses to the data queries over a huge amount of trajectory data. Case studies with a real taxi GPS trajectory dataset (> 30GB) show that our system performs well for on-demand transport assessment and reasoning.\",\n \"Title: Optimizing offline access to social network content on mobile devices\\nYear: 2014\\n\\nAbstract: In this paper, we explore the problem of supporting efficient access to social media contents on social network sites for mobile devices without requiring mobile users to be online all the time. We propose and implement a broker/proxy based architecture that stages data at a broker/proxy, and selectively downloads to the mobile device only those contents that have a high likelihood of being viewed. The system determines the relevance of social media updates that continuously arrive (e.g., Facebook friend updates) for each user. Using knowledge of this relevance and current network/system conditions, we develop scheduling algorithms that determine which social contents are sent to the devices. We develop an Android app providing offline access to Facebook. Our experimental results indicate that our system is energy efficient, which saves energy by 6.9 times for WiFi and 9.1 times for cellular connections. We also use data traces gathered from our app to further drive extensive simulation based evaluations which show that our proposed algorithms provide efficient facilities for tuning the system's performance.\",\n \"Title: Feedback parameter selection for impedance control of series elastic actuators\\nYear: 2014\\n\\nAbstract: The interest of series elastic actuators (SEAs) for legged robots has recently increased to achieve compliant interactions and efficient gaits. However, control of legged robots with SEAs is difficult due to the need to design controllers that take into account both torque and impedance feedback loops. The work presented here addresses this issue by proposing a critically-damped fourth order system gain selection criterion for a cascaded SEA control structure with inner torque and outer impedance feedback loops. Velocity filtering and feedback delays are taken into consideration for stability and impedance performance analysis. We observe and analyze the interdependence between torque and impedance feedback gains to achieve the desired closed loop performance. Based on this analysis we derive a simple gain design criterion to maximize the tracking performance of SEAs. Our final goal is to maximize the output impedance capabilities of SEAs in order to fulfill a wide range of application needs. In contrast to low impedance design studies, we focus here specifically on achieving the highest possible impedance gains of SEAs. Finally, experiments using our UT-SEA are conducted to verify our proposed approach. This study serves as a stepping stone towards utilizing and designing humanoid robots with SEA actuators for mobile behaviors and interaction with cluttered and unknown environments.\",\n \"Title: Parkinson Data Analysis and Interpretation with Data Visualization Methods.\\nYear: 2014\\n\\nAbstract: Information Visualization has been used in many areas and now its applications are growing each day. Modelling and visualization psychological processes, based on the analysis of psychological data can be a real necessary for all experts in this field. In this article we use PCA and person fit statistical for analyzing data, and some visualization tools for modeling to provide some visualizations of the Parkinson patient's information. The results show some meaningful relations between BMI, Age in one side and percentage of some Parkinson patient features that can be appear in men and women on the other side.\",\n \"Title: TenniVis: Visualization for Tennis Match Analysis\\nYear: 2014\\n\\nAbstract: Existing research efforts into tennis visualization have primarily focused on using ball and player tracking data to enhance professional tennis broadcasts and to aid coaches in helping their students. Gathering and analyzing this data typically requires the use of an array of synchronized cameras, which are expensive for non-professional tennis matches. In this paper, we propose TenniVis, a novel tennis match visualization system that relies entirely on data that can be easily collected, such as score, point outcomes, point lengths, service information, and match videos that can be captured by one consumer-level camera. It provides two new visualizations to allow tennis coaches and players to quickly gain insights into match performance. It also provides rich interactions to support ad hoc hypothesis development and testing. We first demonstrate the usefulness of the system by analyzing the 2007 Australian Open men's singles final. We then validate its usability by two pilot user studies where two college tennis coaches analyzed the matches of their own players. The results indicate that useful insights can quickly be discovered and ad hoc hypotheses based on these insights can conveniently be tested through linked match videos.\",\n \"Title: A Bistatic Synthetic Aperture Radar Imagery Simulation of Maritime Scene Using the Extended Nonlinear Chirp Scaling Algorithm\\nYear: 2013\\n\\nAbstract: A bistatic synthetic aperture radar (Bis-SAR) imagery simulation of an extended maritime scene is presented. An efficient facet scattering model is developed to collect the raw coupling scattering data from a ship located on sea surface. Then, to avoid the inefficiency of time-domain algorithms and the azimuth-invariant limit of conventional frequency-domain (FD) methods in the bistatic case, an extended nonlinear chirp scaling (NLCS) algorithm is proposed to handle the bistatic data collected from this facet scattering model. The perfect Bis-SAR simulation results of the ship located on the sea surface could prove the validity of the proposed algorithms as well as the practicability of the model for the Bis-SAR imagery with large squint angle in the FD approach.\",\n \"Title: TrajGraph: A Graph-Based Visual Analytics Approach to Studying Urban Network Centralities Using Taxi Trajectory Data\\nYear: 2016\\n\\nAbstract: We propose TrajGraph, a new visual analytics method, for studying urban mobility patterns by integrating graph modeling and visual analysis with taxi trajectory data. A special graph is created to store and manifest real traffic information recorded by taxi trajectories over city streets. It conveys urban transportation dynamics which can be discovered by applying graph analysis algorithms. To support interactive, multiscale visual analytics, a graph partitioning algorithm is applied to create region-level graphs which have smaller size than the original street-level graph. Graph centralities, including Pagerank and betweenness, are computed to characterize the time-varying importance of different urban regions. The centralities are visualized by three coordinated views including a node-link graph view, a map view and a temporal information view. Users can interactively examine the importance of streets to discover and assess city traffic patterns. We have implemented a fully working prototype of this approach and evaluated it using massive taxi trajectories of Shenzhen, China. TrajGraph's capability in revealing the importance of city streets was evaluated by comparing the calculated centralities with the subjective evaluations from a group of drivers in Shenzhen. Feedback from a domain expert was collected. The effectiveness of the visual interface was evaluated through a formal user study. We also present several examples and a case study to demonstrate the usefulness of TrajGraph in urban transportation analysis.\",\n \"Title: Visual summarization of image collections by fast RANSAC\\nYear: 2016\\n\\nAbstract: In this paper we propose a novel approach to select a summary set of images from a large image collection by improved Random Sample Consensus (RANSAC) and Affinity Propagation (AP) clustering. It can automatically select a small set of representatives to highlight all the significant visual properties of a given image collection. The proposed framework mainly composes four stages. First, the scale-invariant feature of each image is extracted by Scale Invariant Feature Transform (SIFT). Second, keypoints of two images are matched and ranked based on nearest neighbor ratio. The representative dataset of RANSAC is established by a minimal number of optimal matches. Third, the target homographic matrix is fitted based on the representative dataset. Mismatches are filtered out via the homographic matrix. Finally, summarization is automatically formulated as an optimization framework by AP clustering. We conduct experiments on a set of Paris which is consisting of 1000 images downloaded from Flickr. The results show that the proposed approach significantly outperforms other methods.\",\n \"Title: TrajGraph: A Graph-Based Visual Analytics Approach to Studying Urban Network Centralities Using Taxi Trajectory Data\\nYear: 2016\\n\\nAbstract: AbstractWe propose TrajGraph, a new visual analytics method, for studying urban mobility patterns by integrating graph modeling and visual analysis with taxi trajectory data. A special graph is created to store and manifest real traffic information recorded by taxi trajectories over city streets. It conveys urban transportation dynamics which can be discovered by applying graph analysis algorithms. To support interactive, multiscale visual analytics, a graph partitioning algorithm is applied to create region-level graphs which have smaller size than the original street-level graph. Graph centralities, including Pagerank and betweenness, are computed to characterize the time-varying importance of different urban regions. The centralities are visualized by three coordinated views including a node-link graph view, a map view and a temporal information view. Users can interactively examine the importance of streets to discover and assess city traffic patterns. We have implemented a fully working prototype of this approach and evaluated it using massive taxi trajectories of Shenzhen, China. TrajGraph's capability in revealing the importance of city streets was evaluated by comparing the calculated centralities with the subjective evaluations from a group of drivers in Shenzhen. Feedback from a domain expert was collected. The effectiveness of the visual interface was evaluated through a formal user study. We also present several examples and a case study to demonstrate the usefulness of TrajGraph in urban transportation analysis.\",\n \"Title: A Framework for Planning and Controlling Non-Periodic Bipedal Locomotion.\\nYear: 2015\\n\\nAbstract: This study presents a theoretical framework for planning and controlling agile bipedal locomotion based on robustly tracking a set of non-periodic apex states. Based on the prismatic inverted pendulum model, we formulate a hybrid phase-space planning and control framework which includes the following key components: (1) a step transition solver that enables dynamically tracking non-periodic apex or keyframe states over various types of terrains, (2) a robust hybrid automaton to effectively formulate planning and control algorithms, (3) a phase-space metric to measure distance to the planned locomotion manifolds, and (4) a hybrid control method based on the previous distance metric to produce robust dynamic locomotion under external disturbances. Compared to other locomotion frameworks, we have a larger focus on non-periodic gait generation and robustness metrics to deal with disturbances. Such focus enables the proposed control framework to robustly track non-periodic apex states over various challenging terrains and under external disturbances as illustrated through several simulations. Additionally, it allows a bipedal robot to perform non-periodic bouncing maneuvers over disjointed terrains.\",\n \"Title: Hybrid multi-contact dynamics for wedge jumping locomotion behaviors\\nYear: 2015\\n\\nAbstract: Legged robots naturally exhibit continuous and discrete dynamics when maneuvering over level-ground and uneven terrains. In recent years, numerous studies have focused on locomotion hybrid dynamics. However, locomotion on more challenging terrains such as split wedges in Figure 1 has rarely been explored, let alone its hybrid dynamics. In this study, we specifically focus on a two-phase hybrid automaton formulation for this highly steep wedge locomotion. This automaton incorporates both multi-contact and flight single contact phase motions. To dynamically balance and jump upwards on this wedge, an aperiodic phase space planning is used for trajectory generations. Three control strategies are employed simultaneously: internal force control, linear and angular momentum control. Finally, simulation results are shown to verify our strategy's effectiveness.\",\n \"Title: SmartSource: A Mobile Q&A Middleware Powered by Crowdsourcing.\\nYear: 2015\\n\\nAbstract: In this paper, we introduce Smart Source, a crowd sourcing based mobile Question & Answer (Q&A) system that aims to provide mobile information seekers with timely, trustworthy and accurate answers while ensuring that information providers are not inappropriately burdened. We tackle this challenge by taking advantage of both static and dynamic context and semantics from mobile users (e.g., Geolocation, social network, expertise/interest, device sensor profiles, battery level) to identify sources of information (i.e., Workers) that are trusted by the user and accurate enough for the questions at hand. Given a question, the Smart Source broker middleware executes a scalable and efficient worker selection algorithm that uses a Lyapunov optimization framework to maximize the utility of worker selection while guaranteeing the stability of the overall system. An associated assignor selection is used to scale the selection process to a large number of users. We implement the Smart Source prototype system on an Android test bed and thoroughly evaluate the system using real world applications and data, in particular those that involve geospatial questions and answers. Evaluation results indicate that Smart Source is efficient and provides superior worker selection compared to baseline approaches. Smart Source is also highly customizable: it employs a general utility function and provides a control knob to tradeoff the optimality and responding time. We believe that Smart Source will pave a way for new mechanisms of interaction among mobile users.\",\n \"Title: Enabling offline access to Facebook streams on mobile devices\\nYear: 2013\\n\\nAbstract: The recent years have witnessed the wild success of social networks and social media sites such as Facebook, Twitter, LinkedIn, Google+, and Instagram -- indeed, many people rely on these social networks to communicate with their friends, family and community on a day to day basis. Via these sites, users exchange rich media contents, such as video, audio, and images for an enhanced user experience. With the growing popularity of mobile communications, users connect to these social networks using mobile devices (e.g., smartphones, tablets) and expect to derive the same experience no matter how and where they connect. It is reported that 93% of Android smartphone users in India use social networks on their smartphones [6]. Another survey, done in Canada, shows that 61% of users access Facebook through mobile devices [2]. These market reports indicate that social media streams, carrying rich content, have become key aspects of how people view information and how society interacts today.\",\n \"Title: Blowing in the wind\\nYear: 2003\\n\\nAbstract: We present an approach for simulating the natural dynamics that emerge from the coupling of a flow field to lightweight, mildly deformable objects immersed within it. We model the flow field using a Lattice Boltzmann Model (LBM) extended with a subgrid model and accelerate the computation on commodity graphics hardware to achieve real-time simulations. We demonstrate our approach using soap bubbles and a feather blown by wind fields, yet our approach is general enough to apply to other light-weight objects. The soap bubbles illustrate Fresnel reflection, reveal the dynamics of the unseen flow field in which they travel, and display spherical harmonics in their undulations. The free feather floats and flutters in response to lift and drag forces. Our single bubble simulation allows the user to directly interact with the wind field and thereby influence the dynamics in real time.\",\n \"Title: RichNote: Adaptive Selection and Delivery of Rich Media Notifications to Mobile Users\\nYear: 2016\\n\\nAbstract: In recent years, notification services for social networks, mobile apps, messaging systems and other electronic services have become truly ubiquitous. When a new content becomes available, the service sends an instant notification to the user. When the content is produced in massive quantities, and it includes both large-size media and a lot of meta-information, it gives rise to a major challenge of selecting content to notify about and information to include in such notifications. We tackle three important challenges in realizing rich notification delivery: (1) content and presentation utility modeling, (2) notification selection and (3) scheduling of delivery. We consider a number of progressive presentation levels for the content. Since utility is subjective and hard to model, we rely on real data and user surveys. We model the content utility by learning from large-scale real world data collected from Spotify music streaming service. For the utility of the presentation levels we rely on user surveys. Blending these two techniques together, we derive utility of notifications with different presentation levels. We then model the selection and delivery of rich notifications as an optimization problem with a goal to maximize the utility of notifications under resource budget constraints. We validate our system with large-scale simulations driven by the real-world de-identified traces obtained from Spotify. With the help of several baseline approaches we show that our solution is adaptive and resource efficient.\",\n \"Title: A visual analytics approach to high-dimensional logistic regression modeling and its application to an environmental health study\\nYear: 2016\\n\\nAbstract: In the domain of epidemiology, logistic regression modeling is widely used to explain the relationships among explanatory variables and dichotomous outcome variables. However, logistic regression modeling faces challenges such as overfitting, confounding, and multicollinearity when there is a large number of explanatory variables. For example, in the birth defect study presented in this paper, variable selection for building high quality models to identify risk factors from hundreds of pollutant variables is difficult. To address this problem, we propose a novel visual analytics approach to logistic regression modeling for high-dimensional datasets. It leverages the traditional modeling pipeline by providing (1) intuitive visualizations for inspecting statistical indicators and the relationships among the variables and (2) a seamless, effective dimension reduction pipeline for selecting variables for inclusion in high quality logistic regression models. A fully working prototype of this approach has been developed and successfully applied to the birth defect study, which illustrates its effectiveness and efficiency. Its application in an insurance policy study and feedback from domain experts further demonstrate its usefulness.\",\n \"Title: Spot-tracking lens: A zoomable user interface for animated bubble charts\\nYear: 2016\\n\\nAbstract: Zoomable user interfaces are widely used in static visualizations and have many benefits. However, they are not well supported in animated visualizations due to problems such as change blindness and information overload. We propose the spot-tracking lens, a new zoomable user interface for animated bubble charts, to tackle these problems. It couples zooming with automatic panning and provides a rich set of auxiliary techniques to enhance its effectiveness. Our preliminary user studies suggested that, besides allowing users to examine detail information, it can be an engaging approach to exploratory analysis for dynamic data.\",\n \"Title: SemanticTraj: A New Approach to Interacting with Massive Taxi Trajectories.\\nYear: 2017\\n\\nAbstract: Massive taxi trajectory data is exploited for knowledge discovery in transportation and urban planning. Existing tools typically require users to select and brush geospatial regions on a map when retrieving and exploring taxi trajectories and passenger trips. To answer seemingly simple questions such as “What were the taxi trips starting from Main Street and ending at Wall Street in the morning?” or “Where are the taxis arriving at the Art Museum at noon typically coming from?”, tedious and time consuming interactions are usually needed since the numeric GPS points of trajectories are not directly linked to the keywords such as “Main Street”, “Wall Street”, and “Art Museum”. In this paper, we present SemanticTraj, a new method for managing and visualizing taxi trajectory data in an intuitive, semantic rich, and efficient means. With SemanticTraj, domain and public users can find answers to the aforementioned questions easily through direct queries based on the terms. They can also interactively explore the retrieved data in visualizations enhanced by semantic information of the trajectories and trips. In particular, taxi trajectories are converted into taxi documents through a textualization transformation process. This process maps GPS points into a series of street/POI names and pick-up/drop-off locations. It also converts vehicle speeds into user-defined descriptive terms. Then, a corpus of taxi documents is formed and indexed to enable flexible semantic queries over a text search engine. Semantic labels and meta-summaries of the results are integrated with a set of visualizations in a SemanticTraj prototype, which helps users study taxi trajectories quickly and easily. A set of usage scenarios are presented to show the usability of the system. We also collected feedback from domain experts and conducted a preliminary user study to evaluate the visual system.\",\n \"Title: VesselMap: A web interface to explore multivariate vascular data.\\nYear: 2016\\n\\nAbstract: Abstract Hemodynamics plays a key role in the pathological evolution of vascular diseases such as vascular stenosis, plaques and aneurysms. Augmented visualization of relevant hemodynamic and geometric data accelerates engineering designs of diagnostic and therapeutic methods for those vascular diseases. However, four dimensional (4D) hemodynamic data are intrinsically complex. Consequently, exploration of this information has not been streamlined, despite its importance. In this paper, we propose a web interface to explore multivariate hemodynamic data, thereby facilitating the visualization of spatial and temporal relationships among those hemodynamic parameters of interest. The main thrust of this web system is the proposed VesselMap methodology, a 2D representation of vessel structures that provides an overview of all query results without any visual occlusions. Furthermore, in this framework, quantile–quantile plot was also used to compare spatial variations in parameter distributions, thereby greatly aiding in extracting local characteristics of hemodynamic parameters. Using “patient-specific” computational fluid dynamics (CFD) simulations, realistic flow velocity fields were obtained. Based on those CFD-simulated velocity fields, we performed an empirical evaluation to confirm the usefulness of our approach for biomedical engineering applications. We concluded that the proposed VesselMap methodology allowed users to rapidly interact with hemodynamic data of interest, enhancing efficacy of information retrieval.\",\n \"Title: Crowdsourced Mobile Data Transfer with Delay Bound.\\nYear: 2016\\n\\nAbstract: In this article, we design a crowdsourcing system, CrowdMAC, where mobile devices form a local community or marketplace to share network access and transfer data for each other. CrowdMAC enables (i) mobile clients to select and exploit multiple mobile hotspots in its vicinity for data transfer and (ii) mobile hotspots to open their cellular connectivity to admit/serve delay-bounded requests from mobile users for a fee. The evaluations of CrowdMAC indicate that (i) mobile clients can tune preferred trade-offs between cost and delay through a control knob, (ii) mobile hotspots comply with all delay bounds, and (iii) the system ensures stable and efficient transfer.\",\n \"Title: Stabilizing Series-Elastic Point-Foot Bipeds Using Whole-Body Operational Space Control.\\nYear: 2016\\n\\nAbstract: Whole-body operational space controllers (WBOSCs) are versatile and well suited for simultaneously controlling motion and force behaviors, which can enable sophisticated modes of locomotion and balance. In this paper, we formulate a WBOSC for point-foot bipeds with series-elastic actuators (SEA) and experiment with it using a teen-size SEA biped robot. Our main contributions are on devising a WBOS...\",\n \"Title: A Planning and Control Framework for Humanoid Systems: Robust, Optimal, and Real-time Performance.\\nYear: 2017\\n\\nAbstract: Humanoid robots are increasingly demanded to operate in interactive and human-surrounded environments while achieving sophisticated locomotion and manipulation tasks. To accomplish these tasks, roboticists unremittingly seek for advanced methods that generate whole-body coordination behaviors and meanwhile fulfill various planning and control objectives. Undoubtedly, these goals pose fundamental challenges to the robotics and control community. To take an incremental step towards reducing the performance gap between theoretical foundations and real implementations, we present a planning and control framework for the humanoid, especially legged robots, for achieving high performance and generating agile motions. A particular concentration is on the robust, optimal and real-time performance. This framework constitutes three hierarchical layers: First, we present a robust optimal phase-space planning framework for dynamic legged locomotion over rough terrain. This framework is a hybrid motion planner incorporating a series of pivotal components. Second, we take a step toward formally synthesizing high-level reactive planners for whole-body locomotion in constrained environments. We formulate a two-player temporal logic game between the contact planner and its possibly-adversarial environment. Third, we propose a distributed control architecture for the latency-prone humanoid robotic systems. A central experimental phenomenon is observed that the stability of high impedance distributed controllers is highly sensitive to damping feedback delay but much less to stiffness feedback delay. We pursue a detailed analysis of the distributed controllers where damping feedback effort is executed in proximity to the control plant, and stiffness feedback effort is implemented in a latency-prone centralized control process.\",\n \"Title: High-Level Planner Synthesis For Whole-Body Locomotion In Unstructured Environments\\nYear: 2016\\n\\nAbstract: Contact-based decision and planning methods are increasingly being sought for task execution in humanoid robots. However, formal methods from the verification and synthesis communities have not been yet incorporated into the motion planning sequence for complex mobility behaviors in humanoid robots. This study takes a step toward formally synthesizing high-level reactive task planners for whole-body locomotion in unstructured environments. We formulate a two player temporal logic game between the contact planner and its possibly adversarial environment. The resulting discrete planner satisfies the given task specifications expressed in a fragment of temporal logic. The resulting commands are executed by a low-level 3D phase-space motion planner algorithm. We devise various low-level locomotion modes based on centroidal momentum dynamics. Provable correctness of the low-level execution of the synthesized discrete task planner is guaranteed through the so-called simulation relations. Simulations of dynamic locomotion in unstructured environments support the effectiveness of the hierarchical planner protocol.\",\n \"Title: Visual Analytics of Mobility and Transportation: State of the Art and Further Research Directions\\nYear: 2017\\n\\nAbstract: AbstractMany cities and countries are now striving to create intelligent transportation systems that utilize the current abundance of multisource and multiform data related to the functionality and the use of transportation infrastructure to better support human mobility, interests, and lifestyles. Such intelligent transportation systems aim to provide novel services that can enable transportation consumers and managers to be better informed and make safer and more efficient use of the infrastructure. However, the transportation domain is characterized by both complex data and complex problems, which calls for visual analytics approaches. The science of visual analytics is continuing to develop principles, methods, and tools to enable synergistic work between humans and computers through interactive visual interfaces. Such interfaces support the unique capabilities of humans (such as the flexible application of prior knowledge and experiences, creative thinking, and insight) and couple these abilities with machines’ computational strengths, enabling the generation of new knowledge from large and complex data. In this paper, we describe recent developments in visual analytics that are related to the study of movement and transportation systems and discuss how visual analytics can enable and improve the intelligent transportation systems of the future. We provide a survey of literature from the visual analytics domain and organize the survey with respect to the different types of transportation data, movement and its relationship to infrastructure and behavior, and modeling and planning. We conclude with lessons learned and future directions, including social transportation, recommender systems, and policy implications.\",\n \"Title: Reconstructing images corrupted by noise based on D-S evidence theory.\\nYear: 2017\\n\\nAbstract: In this paper, a new algorithm of noise reduction for image based on evidence theory is proposed. The values of all pixels are restricted in interval [0, 1], and set of data in each column is a term of mass function, which can be calculated by D–S composition rule. Judging noise can be achieved by comparing with the value of pixel in middle and of the current one. The noise will be removed by substituting the current value with value computed. An improved accelerated algorithm is also presented by sample window of 2 × 2. As a measure of conflict K with greater value shows that there would be noises within the current sample window. At last, Experiment image “Lena” with additive noise shows as a test sample, that better result can be achieved with the algorithm.\",\n \"Title: Coverage area detection based on Voronoi diagram in wireless sensor network of metro\\nYear: 2016\\n\\nAbstract: The layout of sensor nodes has been playing an important role in health detection of metro tunnel. If the density of nodes are too much, the redundant information would be produced. Oppositely, the completeness cannot be ensured. The research of this paper is to detect the coverage area of wireless sensor network in metro tunnel, which is based on spatial density network Voronoi diagram. The new diagram is extended by classic Voronoi diagrams, and the discrete construction method is introduced. In the end of the paper, the real example indicated that the research has a practical meaning.\",\n \"Title: UrbanFACET: Visually Profiling Cities from Mobile Device Recorded Movement Data of Millions of City Residents.\\nYear: 2017\\n\\nAbstract: Cities are living systems where urban infrastructures and their functions are defined and evolved due to population behaviors. Profiling the cities and functional regions has been an important topic in urban design and planning. This paper studies a unique big data set which includes daily movement data of tens of millions of city residents, and develop a visual analytics system, namely UrbanFACET, to discover and visualize the dynamical profiles of multiple cities and their residents. This big user movement data set, acquired from mobile usersu0027 agnostic check-ins at thousands of phone APPs, is well utilized in an integrative study and visualization together with urban structure (e.g., road network) and POI (Point of Interest) distributions. In particular, we novelly develop a set of information-theory based metrics to characterize the mobility patterns of city areas and groups of residents. These multifaceted metrics including Fluidity, vibrAncy, Commutation, divErsity, and densiTy (FACET) which categorize and manifest hidden urban functions and behaviors. UrbanFACET system further allows users to visually analyze and compare the metrics over different areas and cities in metropolitan scales. The system is evaluated through both case studies on several big and heavily populated cities, and user studies involving real-world users.\",\n \"Title: Guest Editorial Introduction to the Special Issue on Visual Analysis for ITS.\\nYear: 2017\\n\\nAbstract: Sensing technologies, social media, and large-scale computing infrastructures have produced a variety of traffic and transportation data, e.g., human mobility, mobile trajectories, mobile phone calls, traffic, and geographical data. Despite the wealth of research on intelligent transportation systems, contemporary analytical tools are often inadequate for handling the data with the character of la...\",\n \"Title: Towards understanding visually guided locomotion over complex and rough terrain: A phase-space planning method\\nYear: 2017\\n\\nAbstract: As legged robots maneuver over increasingly complex and rough terrains, designing motion planners with the capability of predicting future footsteps becomes imperative. In turn, these planners provide a valuable tool for understanding the fundamental principles underlying human locomotion [2, 3]. In this study, we use our previously proposed phase-space planning framework [1] to analyze human walking over complex terrain. In particular, we highlight (i) the center of mass (CoM) apex-state-based feature of the phase-space planning, and (ii) the role of vision in CoM apex state selection during human walking over complex terrain [2].\",\n \"Title: Robust optimal planning and control of non-periodic bipedal locomotion with a centroidal momentum model\\nYear: 2017\\n\\nAbstract: AbstractThis study presents a theoretical method for planning and controlling agile bipedal locomotion based on robustly tracking a set of non-periodic keyframe states. Based on centroidal momentum dynamics, we formulate a hybrid phase-space planning and control method that includes the following key components: i a step transition solver that enables dynamically tracking non-periodic keyframe states over various types of terrain; ii a robust hybrid automaton to effectively formulate planning and control algorithms; iii a steering direction model to control the robot's heading; iv a phase-space metric to measure distance to the planned locomotion manifolds; and v a hybrid control method based on the previous distance metric to produce robust dynamic locomotion under external disturbances. Compared with other locomotion methodologies, we have a large focus on non-periodic gait generation and robustness metrics to deal with disturbances. This focus enables the proposed control method to track non-periodic keyframe states robustly over various challenging terrains and under external disturbances, as illustrated through several simulations.\",\n \"Title: Using flow feature to extract pulsatile blood flow from 4D flow MRI images.\\nYear: 2017\\n\\nAbstract: 4D flow MRI images make it possible to measure pulsatile blood flow inside deforming vessel, which is critical in accurate blood flow visualization, simulation, and evaluation. Such data has great potential to overcome problems in existing work, which usually does not reflect the dynamic nature of elastic vessels and blood flows in cardiac cycles. However, the 4D flow MRI data is often low-resolution and with strong noise. Due to these challenges, few efforts have been successfully conducted to extract dynamic blood flow fields and deforming artery over cardiac cycles, especially for small artery like carotid. In this paper, a robust flow feature, particularly the mean flow intensity is used to segment blood flow regions inside vessels from 4D flow MRI images in whole cardiac cycle. To estimate this flow feature more accurately, adaptive weights are added to the raw velocity vectors based on the noise strength of MRI imaging. Then, based on this feature, target arteries are tracked in at different time steps in a cardiac cycle. This method is applied to the clinical 4D flow MRI data in neck area. Dynamic vessel walls and blood flows are effectively generated in a cardiac cycle in the relatively small carotid arteries. Good image segmentation results on 2D slices are presented, together with the visualization of 3D arteries and blood flows. Evaluation of the method was performed by clinical doctors and by checking flow volume rates in the vertebral and carotid arteries.\",\n \"Title: Impedance Control and Performance Measure of Series Elastic Actuators.\\nYear: 2018\\n\\nAbstract: Series elastic actuators (SEAs) have become prevalent in torque-controlled robots in recent years to achieve compliant interactions with environments and humans. However, designing optimal impedance controllers and characterizing impedance performance for SEAs with time delays and filtering are still underexplored problems. This article addresses the controller design problem by devising a critica...\",\n \"Title: Generating Chinese Poems from Images Based on Neural Network.\\nYear: 2017\\n\\nAbstract: Chinese classical poetry generation from images is an overwhelmingly challenging work in the field of artificial intelligence. Inspired by recent advances in automatically generating description of an image and Chinese poem generation, in this paper, we present a generative model based on deep recurrent framework that describes images in the form of poems. Our model consists of two parts, one is to extract information according to the semantics presented in images, and the other is to generate each line of the poem incrementally according to the extracted semantic information from the images by a recurrent neural network. Experimental results thoroughly demonstrate the effectiveness of our approach by manual evaluation.\",\n \"Title: Variable stiffness control of series elastic actuated biped locomotion.\\nYear: 2018\\n\\nAbstract: This study investigates the problem of dynamic walking impact on a biped robot. Two online variable stiffness control algorithms, i.e., torque balance algorithm (TBA) and surface fitting algorithm (SFA), are proposed based on virtual spring leg to achieve compliant performance. These two algorithms target on solving the high nonlinearity commonly existing in legged robot actuators. A planar biped robot experiment platform is designed for testing the proposed variable stiffness control. The experiments compare the performance of TBA and SFA and verify that applying the variable stiffness control of a virtual spring leg is capable of effectively absorbing unforeseen ground impacts and thus improving stability and safety of walking biped robots.\",\n \"Title: Enhancing Person Retrieval with Joint Person Detection, Attribute Learning, and Identification.\\nYear: 2018\\n\\nAbstract: Person re-identification receives increasing attention in recent years. However, most works assume the persons have been well cropped from the whole scene images, and only focus on learning features and metrics. This paper considers the person re-identification problem in a real-world scenario, which should consider detection and identification simultaneously. This paper proposes a multi-task learning framework for person retrieval in the wild. Person attribute learning is exploited in our framework to enhance person retrieval. Our work consists of two main contributions: (1) we present a 11 image-level attribute annotations for each image in the large-scale PRW [ 27] dataset, and (2) we develop an end-to-end person retrieval framework which jointly learns person detector, attribute detectors, and visual embeddings in a multi-task learning manner. We evaluate the effectiveness of the proposed approach on two tasks, i.e. person attribute recognition and person re-identification. Experimental results have demonstrated the effectiveness of the proposed approach.\",\n \"Title: A Battery Monitoring Ic With An Isolated Communication Interface For Electric Vehicles\\nYear: 2018\\n\\nAbstract: This paper presents a Li-ion battery monitoring and protection IC suitable for monitoring 12 battery cells for clcctric vehicles (EVs). A two-wire, transformer based, isolated interface is proposed to provide the interface for the cascaded ICs. The interface uses the \\\"balanced\\\" two-wire technology and encodes the four SPI signals into DC-free pulse that can be coupled by a transformer, which features high-speed, low electromagnetic interference (EMI), and reliable data transmission. The IC was fabricated in a 0.18 mu m, 60 V BCD process, with a total chip area of 4.4 X 3.6 mm(2). Measurement results show that the proposed interface can achieve a data rate up to 1 Mbps. Meanwhile, the measured current consumption is less than 45 mu A in sleeping mode.\",\n \"Title: Reactive Task and Motion Planning for Robust Whole-Body Dynamic Locomotion in Constrained Environments.\\nYear: 2018\\n\\nAbstract: Contact-based decision and planning methods are becoming increasingly important to endow higher levels of autonomy for legged robots. Formal synthesis methods derived from symbolic systems have great potential for reasoning about high-level locomotion decisions and achieving complex maneuvering behaviors with correctness guarantees. This study takes a first step toward formally devising an architecture composed of task planning and control of whole-body dynamic locomotion behaviors in constrained and dynamically changing environments. At the high level, we formulate a two-player temporal logic game between the multi-limb locomotion planner and its dynamic environment to synthesize a winning strategy that delivers symbolic locomotion actions. These locomotion actions satisfy the desired high-level task specifications expressed in a fragment of temporal logic. Those actions are sent to a robust finite transition system that synthesizes a locomotion controller that fulfills state reachability constraints. This controller is further executed via a low-level motion planner that generates feasible locomotion trajectories. We construct a set of dynamic locomotion models for legged robots to serve as a template library for handling diverse environmental events. We devise a replanning strategy that takes into consideration sudden environmental changes or large state disturbances to increase the robustness of the resulting locomotion behaviors. We formally prove the correctness of the layered locomotion framework guaranteeing a robust implementation by the motion planning layer. Simulations of reactive locomotion behaviors in diverse environments indicate that our framework has the potential to serve as a theoretical foundation for intelligent locomotion behaviors.\",\n \"Title: Distributed Impedance Control of Latency-Prone Robotic Systems with Series Elastic Actuation.\\nYear: 2018\\n\\nAbstract: Robotic systems are increasingly relying on distributed feedback controllers to tackle complex and latency-prone sensing and decision problems. These demands come at the cost of a growing computational burden and, as a result, larger controller latencies. To maximize robustness to mechanical disturbances and achieve high control performance, we emphasize the necessity for executing damping feedback in close proximity to the control plant while allocating stiffness feedback in a latency-prone centralized control process. Additionally, series elastic actuators (SEAs) are becoming prevalent in torque-controlled robots during recent years to achieve compliant interactions with environments and humans. However, designing optimal impedance controllers and characterizing impedance performance for SEAs with time delays and filtering are still under-explored problems. The presented study addresses the optimal controller design problem by devising a critically-damped gain design method for a class of SEA cascaded control architectures, which is composed of outer-impedance and inner-torque feedback loops. Via the proposed controller design criterion, we adopt frequency-domain methods to thoroughly analyze the effects of time delays, filtering and load inertia on SEA impedance performance. These results are further validated through the analysis, simulation, and experimental testing on high-performance actuators and on an omnidirectional mobile base.\",\n \"Title: Distributed filtering for time-varying networked systems with sensor gain degradation and energy constraint: a centralized finite-time communication protocol scheme.\\nYear: 2018\\n\\nAbstract: This paper focuses on the distributed filtering problem for a class of time-varying networked systems with sensor gain degradation and energy constrained communication protocol. To satisfy the requirement of power consumption and reduce the schedule computing complexity, centralized cyclic finite-time communication strategy optimization is taken into account. The networked system considered in this paper consists of spatially distributed sensors linked to their neighbor sensors, where each sensor node suffers from different gain degradation, and the transmission decisions of all the communication channels obey the centralized transmission schedule strategy identically. First, we present scattered communication action based on single-sensor transmission modeling with an energy constraint. Subsequently, an optimal communication protocol considering expected average error covariance is derived between the target system and each sensor node over the distributed sensor systems, based on a centralized finite-time scheme. Finally, by transforming the overall estimation error covariance of the systems at each sampling time into quadratic form, a conditionally unbiased least-square recursive distributed filtering technique over the networked system is designed at each sensor node. The system stability condition under such an optimal schedule is also accomplished with bounded covariance. A numerical example is provided to demonstrate the utility and effectiveness of the distributed filtering technique using the proposed optimized energy constrained communication protocol.\",\n \"Title: Novel Stability Analysis of Full Order Observer for Induction Motor Drive\\nYear: 2018\\n\\nAbstract: Flux observation plays an important part in induction motor drive, among which full order observer is focused on mostly due to its excellent attributes, such as close loop simultaneous estimation of motor flux and speed, high immunity to motor parameter variation and so on. Just because flux observation and speed identification relate with each other, the system stability analysis is no easy to implement. So far, stability analysis was almost realized from the view of speed identification with flux amplitude though to be constant, which lacks in strict proof and not comprehensive, making flux observation stability not clear. In this paper, stability is made by decomposing observer system to two subsystem using two scale approach, with the rate of flux observation converging to its real counterpart differing from that of speed identification converging to its real counterpart substantially. Analysis is made of flux observation stability. Simulations validate the analysis.\",\n \"Title: Efficient Numerical Full-Polarized Facet-Based Model for EM Scattering from Rough Sea Surface within a Wide Frequency Range.\\nYear: 2019\\n\\nAbstract: A full-polarized facet based scattering model (FPFSM) for investigating the electromagnetic (EM) scattering by two-dimensional electrically large sea surfaces with high efficiency at high microwave bands is proposed. For this method, the scattering field over a large sea facet in a diffuse scattering region is numerically deduced according to the Bragg scattering mechanism. In regard to near specular directions, a novel approach is proposed to calculate the scattered field from a sea surface based on the second order small slope approximation (SSA-II), which saves computer memory considerably and is able to analyze the EM scattering by electrically large sea surfaces. The feasibility of this method in evaluating the radar returns from the sea surface is proved by comparing the normalized radar cross sections (NRCS) and the Doppler spectrum with the SSA-II. Then NRCS results in monostatic and bistatic configurations under different polarization states, scattering angles and wind speeds are analyzed as well as the Doppler spectrum at Ka-band. Numerical results show that the FPFSM is a reliable and efficient method to analyze the full-polarized scattering characteristics from electrically large sea surface within a wide frequency range.\",\n \"Title: Adaptively Exploring Population Mobility Patterns in Flow Visualization.\\nYear: 2017\\n\\nAbstract: Thanks to the ubiquitous cell phone use, we have never been so close to uncover population mobility patterns in urban area. While some researches utilize cellphone call records to mine population patterns, few works aim to depict population movement in adaptively spatial and temporal representations, i.e., from a community, a district in the city over an hour, a day to a week. In this paper, we co...\",\n \"Title: Improved Rao-Blackwellised particle filter based on randomly weighted particle swarm optimization.\\nYear: 2018\\n\\nAbstract: In this paper, a new Rao-Blackwellised particle filter simultaneous localization and mapping method based on randomly weighted particle swarm optimization is proposed in order to solve some problems in the Rao-Blackwellised particle filter, including the depletion of particles and the loss of the diversity in the process of resampling. The particle swarm optimization strategy is introduced in the modified algorithm, and the inertia weight is randomly set. Modified particle swarm optimization method is utilized to optimize the particle set in order to avoid particle degenerating and to keep the diversity. The proposed algorithm is simulated in the Qt platform. To verify the proposed method, the experiment is performed using turtlebot robots under the robot operating system. Results show that the proposed method is superior than extended Kalman filter based on simultaneous localization and mapping method.\",\n \"Title: QuteVis: Visually Studying Transportation Patterns Using Multisketch Query of Joint Traffic Situations\\nYear: 2021\\n\\nAbstract: QuteVis uses multisketch query and visualization to discover specific times and days in history with specified joint traffic patterns at different city locations. Users can use touch input devices to define, edit, and modify multiple sketches on a city map. A set of visualizations and interactions is provided to help users browse and compare retrieved traffic situations and discover potential influential factors. QuteVis is built upon a transport database that integrates heterogeneous data sources with an optimized spatial indexing and weighted similarity computation. An evaluation with real-world data and domain experts demonstrates that QuteVis is useful in urban transportation applications in modern cities.\",\n \"Title: Fully parallelized Lattice Boltzmann scheme for fast extraction of biomedical geometry.\\nYear: 2019\\n\\nAbstract: We develop a fully parallel numerical method which quickly performs 2D and 3D segmentation on GPU to extract anatomical structures from medical images. The algorithm solves the level set equations completely within a Lattice Boltzmann model (LBM). Compared with existing LBM-based segmentation approaches, a parallel distance field regularization is added to the LBM computing scheme to keep computation stable with large time step iteration. This approach also avoids external regularization which has been a major impediment to direct parallelization of level set evolution with LBM. It allows the whole computing process to be efficiently executed on GPU. Moreover, the method can be incorporated with different image features to adopt in various image segmentation tasks. Therefore, our method enables fully GPU accelerated geometric extraction from medical images, leading to high computing performance which is demanded in many practical applications. This method is used to exactly accurate 2D and 3D anatomical structures from many real world CT and MRI images. The achieved results can also directly feed required boundary information to LBM-based hemodynamics simulation.\",\n \"Title: Sparsity-regularized feature selection for multi-class remote sensing image classification\\nYear: 2020\\n\\nAbstract: Remote sensing image classification plays an important role in a wide range of applications and has caused widely concerns. During the last few years, great efforts have been made to develop a number of scene classification methods for remote sensing images. However, the existing remote sensing image classification methods do not perform satisfactorily in dealing with multi-class classification problems and rely heavily on the quality of data sets. These disadvantages seriously restrict the application of remote sensing image, including industrial research, analysis and calculation of land use and land coverage. To this end, this paper proposes a remote sensing image classification algorithm based on the sparse regularized feature learning method. Specifically, after constructing bag of features by using speeded up robust features extraction algorithm, direct sparsity optimization-based feature selection method is applied for selecting discriminative features, which is used for constructing support vector machine classifier model. The proposed algorithm has been evaluated and compared with other advanced feature selection methods on four public remote sensing image data sets. The experimental results demonstrate the effectiveness of our proposed image classification algorithm, which has been successfully applied to remote sensing image classification tasks.\",\n \"Title: Robust Bipedal Locomotion Based on a Hierarchical Control Structure\\nYear: 2019\\n\\nAbstract: To improve biped locomotion's robustness to internal and external disturbances, this study proposes a hierarchical structure with three control levels. At the high level, a foothold sequence is generated so that the Center of Mass (CoM) trajectory tracks a planned path. The planning procedure is simplified by selecting the midpoint between two consecutive Center of Pressure (CoP) points as the feature point. At the middle level, a novel robust hybrid controller is devised to drive perturbed system states back to the nominal trajectory within finite cycles without chattering. The novelty lies in that the hybrid controller is not subject to linear CoM dynamic constraints. The hybrid controller consists of two sub-controllers: an oscillation controller and a smoothing controller. For the oscillation controller, the desired CoM height is specified as a sine-shaped function, avoiding a new attractive limit cycle. However, this controller results in the inevitable chattering because of discontinuities. A smoothing controller provides continuous properties and thus can inhibit the chattering problem, but has a smaller region of attraction compared with the oscillation controller. A hybrid controller merges the two controllers for a smooth transition. At the low level, the desired CoM motion is defined as tasks and embedded in a whole body operational space (WBOS) controller to compute the joint torques analytically. The novelty of the low-level controller lies in that within the WBOS framework, CoM motion is not subject to fixed CoM dynamics and thus can be generalized.\",\n \"Title: Unsupervised Video Summarization Via Clustering Validity Index\\nYear: 2020\\n\\nAbstract: Although lots of the prior works have been proposed to solve the representative selection problem of video summarization, the main difficulty is still left for determining the optimal representatives' number of the raw videos that are not annotated. In this paper, we propose an unsupervised video summarization method by motion-based frame selection and a novel clustering validity indexes to determine the optimal representatives of the original video. The proposed framework segments shots and selects candidate frames by evaluating their forward and backward motion and can automatically select representatives to highlight all the significant visual properties. Shots are segmented uniformly and the frame with the largest motion is extracted in each segmentation to form the video candidate frame subset. Then Affinity Propagation combined with the validity index is used to automatically select the optimal representatives from the candidate frame subset. Our experimental result on several benchmark datasets demonstrates the robustness and effectiveness of our proposed method.\",\n \"Title: Upsilon-Nonparallel Parametric Margin Fuzzy Support Vector Machine\\nYear: 2021\\n\\nAbstract: Classification problem is an important research direction in machine learning. upsilon-nonparallel support vector machine (upsilon-NPSVM) is an important classifier used to solve classification problems. It is widely used because of its structural risk minimization principle, kernel trick, and sparsity. However, when solving classification problems, upsilon-NPSVM will encounter the problem of sample noises and heteroscedastic noise structure, which will affect its performance. In this paper, two improvements are made on the upsilon-NPSVM model, and a v-nonparallel parametric margin fuzzy support vector machine (parv-FNPSVM) is established. On the one hand, for the noises that may exist in the data set, the neighbor information is used to add fuzzy membership to the samples, so that the contribution of each sample to the classification is treated differently. On the other hand, in order to reduce the effect of heteroscedastic structure, an insensitive loss function is introduced. The advantages of the new model are verified through UCI machine learning standard data set experiments. Finally, Friedman test and Bonferroni-Dunn test are used to verify the statistical significance of it.\",\n \"Title: Safe Reinforcement Learning With Stability Guarantee for Motion Planning of Autonomous Vehicles\\nYear: 2021\\n\\nAbstract: Reinforcement learning with safety constraints is promising for autonomous vehicles, of which various failures may result in disastrous losses. In general, a safe policy is trained by constrained optimization algorithms, in which the average constraint return as a function of states and actions should be lower than a predefined bound. However, most existing safe learning-based algorithms capture s...\",\n \"Title: A Visual Designer Of Layer-Wise Relevance Propagation Models\\nYear: 2021\\n\\nAbstract: Layer-wise Relevance Propagation (LRP) is an emerging and widely-used method for interpreting the prediction results of convolutional neural networks (CNN). LRP developers often select and employ different relevance backpropagation rules and parameters, to compute relevance scores on input images. However, there exists no obvious solution to define a \\\"best\\\" LRP model. A satisfied model is highly reliant on pertinent images and designers' goals. We develop a visual model designer, named as VisLRPDesigner, to overcome the challenges in the design and use of LRP models. Various LRP rules are unified into an integrated framework with an intuitive workflow of parameter setup. VisLRPDesigner thus allows users to interactively configure and compare LRP models. It also facilitates relevance-based visual analysis with two important functions: relevance-based pixel flipping and neuron ablation. Several use cases illustrate the benefits of VisLRPDesigner. The usability and limitation of the visual designer is evaluated by LRP users.\",\n \"Title: Terrain-Perception-Free Quadrupedal Spinning Locomotion on Versatile Terrains: Modeling, Analysis, and Experimental Validation\\nYear: 2021\\n\\nAbstract: Dynamic quadrupedal locomotion over rough terrains reveals remarkable progress over the last few decades. Small-scale quadruped robots are adequately flexible and adaptable to traverse uneven terrains along the sagittal direction, such as slopes and stairs. To accomplish autonomous locomotion navigation in complex environments, spinning is a fundamental yet indispensable functionality for legged robots. However, spinning behaviors of quadruped robots on uneven terrain often exhibit position drifts. Motivated by this problem, this study presents an algorithmic method to enable accurate spinning motions over uneven terrain and constrain the spinning radius of the center of mass (CoM) to be bounded within a small range to minimize the drift risks. A modified spherical foot kinematics representation is proposed to improve the foot kinematic model and rolling dynamics of the quadruped during locomotion. A CoM planner is proposed to generate a stable spinning motion based on projected stability margins. Accurate motion tracking is accomplished with linear quadratic regulator (LQR) to bind the position drift during the spinning movement. Experiments are conducted on a small-scale quadruped robot and the effectiveness of the proposed method is verified on versatile terrains including flat ground, stairs, and slopes.\",\n \"Title: Adversarially Regularized Policy Learning Guided by Trajectory Optimization.\\nYear: 2022\\n\\nAbstract: Recent advancement in combining trajectory optimization with function approximation (especially neural networks) shows promise in learning complex control policies for diverse tasks in robot systems. Despite their great flexibility, the large neural networks for parameterizing control policies impose significant challenges. The learned neural control policies are often overcomplex and non-smooth, which can easily cause unexpected or diverging robot motions. Therefore, they often yield poor generalization performance in practice. To address this issue, we propose adVErsarially Regularized pOlicy learNIng guided by trajeCtory optimizAtion (VERONICA) for learning smooth control policies. Specifically, our proposed approach controls the smoothness (local Lipschitz continuity) of the neural control policies by stabilizing the output control with respect to the worst-case perturbation to the input state. Our experiments on robot manipulation show that our proposed approach not only improves the sample efficiency of neural policy learning but also enhances the robustness of the policy against various types of disturbances, including sensor noise, environmental uncertainty, and model mismatch.\",\n \"Title: Geo-Context Aware Study of Vision-Based Autonomous Driving Models and Spatial Video Data\\nYear: 2022\\n\\nAbstract: Vision-based deep learning (DL) methods have made great progress in learning autonomous driving models from large-scale crowd-sourced video datasets. They are trained to predict instantaneous driving behaviors from video data captured by on-vehicle cameras. In this paper, we develop a geo-context aware visualization system for the study of Autonomous Driving Model (ADM) predictions together with l...\",\n \"Title: Reactive Locomotion Decision-Making and Robust Motion Planning for Real-Time Perturbation Recovery\\nYear: 2022\\n\\nAbstract: In this paper, we examine the problem of push recovery for bipedal robot locomotion and present a reactive decision-making and robust planning framework for locomotion resilient to external perturbations. Rejecting perturbations is an essential capability of bipedal robots and has been widely studied in the locomotion literature. However, adversarial disturbances and aggressive turning can lead to negative lateral step width (i.e., crossed-leg scenarios) with unstable motions and self-collision risks. These motion planning problems are computationally difficult and have not been explored under a hierarchically integrated task and motion planning method. We explore a planning and decision-making framework that closely ties linear-temporal-logic-based reactive synthesis with trajectory optimization incorporating the robot's full-body dynamics, kinematics, and leg collision avoidance constraints. Between the high-level discrete symbolic decision-making and the low-level continuous motion planning, behavior trees serve as a reactive interface to handle perturbations occurring at any time of the locomotion process. Our experimental results show the efficacy of our method in generating resilient recovery behaviors in response to diverse perturbations from any direction with bounded magnitudes.\",\n \"Title: Mass Estimation of a Moving Object Through Minimal Manipulation Interaction\\nYear: 2021\\n\\nAbstract: In this paper, we study the problem of dynamic interaction between a robot and an unknown object (e.g., catching a ball, or handing off an object during locomotion). In particular, we propose a method for estimating the inertial parameters of an object during dynamic interaction, while minimally altering the trajectory of the object - a minimal interaction approach. Our method combines trajectory estimation (e.g., using standard methods from computer vision) with a model-based estimator that exploits the robot's known dynamic model. We first develop the method for a generalized three-dimensional problem, and then evaluate the method for the case of an object moving along a linear trajectory. We present experimental results obtained using a KUKA iiwa 7 interacting with rolling balls of varying mass. Our experiments demonstrate that the mass of the objects can be accurately estimated at the moment of impact when accurate object trajectory estimates are available, and that significant improvement can be obtained by incorporating force measurements at the contact point while following the object.\",\n \"Title: Mediating Between Contact Feasibility and Robustness of Trajectory Optimization Through Chance Complementarity Constraints\\nYear: 2021\\n\\nAbstract: As robots move from the laboratory into the real world, motion planning will need to account for model uncertainty and risk. For robot motions involving intermittent contact, planning for uncertainty in contact is especially important, as failure to successfully make and maintain contact can be catastrophic. Here, we model uncertainty in terrain geometry and friction characteristics, and combine a risk-sensitive objective with chance constraints to provide a trade-off between robustness to uncertainty and constraint satisfaction with an arbitrarily high feasibility guarantee. We evaluate our approach in two simple examples: a push-block system for benchmarking and a single-legged hopper. We demonstrate that chance constraints alone produce trajectories similar to those produced using strict complementarity constraints; however, when equipped with a robust objective, we show the chance constraints can mediate a trade-off between robustness to uncertainty and strict constraint satisfaction. Thus, our study may represent an important step towards reasoning about contact uncertainty in motion planning.\",\n \"Title: A Low-Jitter Harmonic-Free All-Digital Delay-Locked Loop for Multi-Channel Vernier TDC\\nYear: 2022\\n\\nAbstract: This paper presents a low jitter All-Digital Delay-Locked Loop (ADDLL) with fast lock time and process immunity. A coarse locking algorithm is proposed to prevent harmonic locking with just a small increase in hardware resources. In order to effectively solve the dithering phenomenon after locking, a replica delay line and a modified binary search algorithm with two modes were introduced in our ADDLL, which can significantly reduce the peak-to-peak jitter of the replica delay line. In addition, digital codes for a replica delay line can be conveniently applied to the delay line of multi-channel Vernier TDC while maintaining consistency between channels. The proposed ADDLL has been designed in 55 nm CMOS technology. In addition, the post-layout simulation results show that when operated at 1.2 V, the proposed ADDLL locks within 37 cycles and has a closed-loop characteristic, the peak-to-peak and root-mean-square jitter at 800 MHz are 6.5 ps and 1.18 ps, respectively. The active area is 0.024 mm(2) and the power consumption at 800 MHz is 6.92 mW. In order to verify the performance of the proposed ADDLL, an architecture of dual ADDLL is applied to Vernier TDC to stabilize the Vernier delay lines against the process, voltage, and temperature (PVT) variations. With a 600 MHz operating frequency, the TDC achieves a 10.7 ps resolution, and the proposed ADDLL can keep the resolution stable even if PVT varies.\",\n \"Title: Safe Learning for Uncertainty-Aware Planning via Interval MDP Abstraction\\nYear: 2022\\n\\nAbstract: We study the problem of refining satisfiability bounds for partially-known stochastic systems against planning specifications defined using syntactically co-safe Linear Temporal Logic (scLTL). We propose an abstraction-based approach that iteratively generates high-confidence Interval Markov Decision Process (IMDP) abstractions of the system from high-confidence bounds on the unknown component of the dynamics obtained via Gaussian process regression. In particular, we develop a synthesis strategy to sample the unknown dynamics by finding paths which avoid specification-violating states using a product IMDP. We further provide a heuristic to choose among various candidate paths to maximize the information gain. Finally, we propose an iterative algorithm to synthesize a satisfying control policy for the product IMDP system. We demonstrate our work with a case study on mobile robot navigation.\",\n \"Title: Momentum-Aware Trajectory Optimization and Control for Agile Quadrupedal Locomotion\\nYear: 2022\\n\\nAbstract: In this letter, we present a versatile hierarchical offline planning algorithm, along with an online control pipeline for agile quadrupedal locomotion. Our offline planner alternates between optimizing centroidal dynamics for a reduced-order model and whole-body trajectory optimization, with the aim of achieving dynamics consensus. Our novel momentum-inertia-aware centroidal optimization, which uses an equimomental ellipsoid parameterization, is able to generate highly acrobatic motions via \\\"inertia shaping\\\". Our whole-body optimization approach significantly improves upon the quality of standard DDP-based approaches by iteratively exploiting feedback from the centroidal level. For online control, we have developed a novel convex model predictive control scheme through a linear transformation of the full centroidal dynamics. Our controller can efficiently optimize for both contact forces and joint accelerations in single optimization, enabling more straightforward tracking for momentum-rich motions compared to existing quadrupedal MPC controllers. We demonstrate the capability and generality of our trajectory planner on four different dynamic maneuvers. We then present one hardware experiment on the MIT Mini Cheetah platform to demonstrate the performance of the entire planning and control pipeline on a twisting jump maneuver.\",\n \"Title: Interactive Visualization and Capture of Geo-Coded Multimedia Data on Mobile Devices\\nYear: 2021\\n\\nAbstract: In digital community applications, geo-coded multimedia data including spatial videos, speech, and geo-narratives are collected and utilized by community users and researchers from multiple fields. It is often preferred that these data can be captured, visualized, and explored directly on mobile phones and tablets interactively. In this paper, we present a Geo-Video Mobile Application (GVM App) that collects geo-coded multimedia data for experts to process and analyze over an interactive visual exploration. This mobile App integrates user interactivity, AI-based semantic image segmentation, and audio transcription for effective data extraction and utilization. Then visualization functions are designed to quickly present geographical, semantic, and street view visual information for knowledge discovery. The users of this tool can include community workers, teachers, and tourists, and also span across multiple social disciplines in digital humanity studies.\",\n \"Title: Visual feature synthesis with semantic reconstructor for traditional and generalized zero-shot object classification\\nYear: 2022\\n\\nAbstract: Zero-shot learning (ZSL) addresses the novel object recognition problem by leveraging semantic embedding to transfer knowledge from seen categories to unseen categories. Generative ZSL models synthesize the visual features of unseen classes and convert ZSL task into a classical supervised learning problem. These generative ZSL models are trained by using the seen classes. Although promising progress has been achieved in the ZSL and generalized zero-shot learning (GZSL) tasks. The existing approaches still suffer from a strong bias problem between unseen and seen classes, where unseen objects in the target domain tend to be recognized as seen classes in the source domain. To deal with the problem, we propose a novel named semantic consistent Wasserstein generative adversarial network (scWGAN), which uses a semantic reconstructor to reconstruct semantic embeddings from generated visual features by incorporating a novel Semantic Consistent Loss noted L rec. The Semantic Consistent Loss guides our proposed scWGAN to generate visual features that mirror the semantic relationships between seen and unseen classes. We also introduce a visual classifier to constrain visual feature generator. Extensive experiments show that the proposed approach is superior to previous state-of-the-art works under both traditional ZSL and challenging GZSL settings on six popular data sets AWA1, AWA2, CUB, APY, and SUN.\",\n \"Title: Estimator-based iterative deviation-free residual generator for fault detection under random access protocol\\nYear: 2022\\n\\nAbstract: This paper proposes an estimator-based iterative deviation-free residual generator (IDRG) for linear discrete-time stochastic systems. The communication between intelligent nodes and the remote estimator is realized by adopting a shared network. With the purpose of random access protocol (RAP) is utilized to schedule the data transmission process, according to which only one node at one instant is selected to get access to the communication network. The aim of the addressed problem is to detect the occurrence and disappearance of the faulty signal via utilizing the designed estimator. By solving an optimization problem subject to the deviation-free constraint, a novel batch estimator is firstly designed with finite response. Then, the IDRG is developed by extracting the residual signal out of the proposed estimator. By adopting the norm of the residual as the evaluation function, the Chebyshev inequalities are used to obtain the lower and upper stochastic thresholds. Finally, an illustrative example is given to demonstrate that the designed IDRG can detect the occurrence and disappearance of the faulty signals in a short transient stage, and is capable of reducing the false alarm rate in comparison to the benchmark Kalman filter residual generator (KFRG).\",\n \"Title: Unbiasedness-constrained least squares state estimation for time-varying systems with missing measurements under round-robin protocol\\nYear: 2022\\n\\nAbstract: In this paper, we present an unbiasedness-constrained approach to deal with the state estimation issue for a class of time-varying stochastic systems subject to missing measurements. The state estimates are generated from measurements collected by multiple sensing nodes whose information are transmitted via communication networks under scheduling of the Round-Robin protocol. The purpose of the addressed problem is to design an optimal state estimation algorithm in the sense of least mean square with an unknown initial condition in the existence of possible data missing. By resorting to the batch form technique, the optimal filter is proposed by minimising the estimation error covariance in the sense of matrix trace subject to the unbiasedness constraint. Then, a recursive computational algorithm is exploited for the optimal filter to facilitate practical realisation. Finally, simulations are carried out to demonstrate that the proposed method can be utilised to handle missing measurements in the multi-sensor systems when the initial states are unavailable, which outperforms the Kalman filter especially in the initial stage.\",\n \"Title: A 7.4-Bit ENOB 600 MS/s FPGA-Based Online Calibrated Slope ADC without External Components\\nYear: 2022\\n\\nAbstract: A slope analog-to-digital converter (ADC) amenable to be fully implemented on a digital field programmable gate array (FPGA) without requiring any external active or passive components is proposed in this paper. The amplitude information, encoded in the transition times of a standard LVDS differential input-driven by the analog input and by the reference slope generated by an FPGA output buffer-is retrieved by an FPGA time-to-digital converter. Along with the ADC, a new online calibration algorithm is developed to mitigate the influence of process, voltage, and temperature variations on its performance. Measurements on an ADC prototype reveal an analog input range from 0.3 V to 1.5 V, a least significant bit (LSB) of 2.6 mV, and an effective number of bits (ENOB) of 7.4-bit at 600 MS/s. The differential nonlinearity (DNL) is in the range between -0.78 and 0.70 LSB, and the integral nonlinearity (INL) is in the range from -0.72 to 0.78 LSB.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":110,"string":"110"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":257,"string":"257"}}},{"rowIdx":258,"cells":{"question_id":{"kind":"string","value":"Darius Burschka"},"question":{"kind":"string","value":"Generate an abstract for the title \"Efficient camera-based pose estimation for real-time applications\" using the following items: Mobile robotics, image-based localization, single camera, robust pose estimation, online capability."},"answer":{"kind":"string","value":"Accurate online localization is crucial for mobile robotics. In this paper, we describe a real-time image-based localization technique, which is based on a single calibrated camera. This can be supported by a second camera to improve accuracy and to provide the correct translational scale. Our goal is a robust and unbiased pose estimation in highly dynamic scenes on resource-limited systems. The presented approach is characterized through significantly improved robustness of the pose estimation, a novel approach for stereo subpixel accurate landmark initialization, and the speed-up of conventional tracking routines to achieve online capability. Although the algorithm is designed for accurate, online short-range egomotion estimation in hand-held scanning devices, it can be used for any mobile robot application as shown in this paper. Various tests and experimental results with a mobile platform and a hand-held 3D modeler are presented and discussed."},"correct_answer":{"kind":"string","value":"Accurate online localization is crucial for mobile robotics. In this paper, we describe a real-time image-based localization technique, which is based on a single calibrated camera. This can be supported by a second camera to improve accuracy and to provide the correct translational scale. Our goal is a robust and unbiased pose estimation in highly dynamic scenes on resource-limited systems. The presented approach is characterized through significantly improved robustness of the pose estimation, a novel approach for stereo subpixel accurate landmark initialization, and the speed-up of conventional tracking routines to achieve online capability. Although the algorithm is designed for accurate, online short-range egomotion estimation in hand-held scanning devices, it can be used for any mobile robot application as shown in this paper. Various tests and experimental results with a mobile platform and a hand-held 3D modeler are presented and discussed."},"documents":{"kind":"list like","value":["Title: The 4D Touchpad: Unencumbered HCI With VICs.\nYear: 2003\n\nAbstract: Abstract, We present a platform for human-machine in-terfaces that provides functionality for robust, unencumbered interaction: the 4D Touchpad (4DT). The goal is direct in-teraction with interface components through intuitive actions and gestures. The 4DT is based on the 3D-2D Projection-based mode of the VICs framework. The fundamental idea behind VICs is that expensive global image processing with user modeling and tracking is not necessary in general vision-based HCI. Instead, interface components operating under simple-to-complex rules in local image regions provide more robust and less costly functionality with 3 spatial dimensions and 1 temporal dimension. A prototype realization of the 4DT platform is presented; it operates through a set of planar","Title: Stochastic global optimization for robust point set registration\nYear: 2011\n\nAbstract: In this paper, we propose a new algorithm for pairwise rigid point set registration with unknown point correspondences. The main properties of our method are noise robustness, outlier resistance and global optimal alignment. The problem of registering two point clouds is converted to a minimization of a nonlinear cost function. We propose a new cost function based on an inverse distance kernel that significantly reduces the impact of noise and outliers. In order to achieve a global optimal registration without the need of any initial alignment, we develop a new stochastic approach for global minimization. It is an adaptive sampling method which uses a generalized BSP tree and allows for minimizing nonlinear scalar fields over complex shaped search spaces like, e.g., the space of rotations. We introduce a new technique for a hierarchical decomposition of the rotation space in disjoint equally sized parts called spherical boxes. Furthermore, a procedure for uniform point sampling from spherical boxes is presented. Tests on a variety of point sets show that the proposed registration method performs very well on noisy, outlier corrupted and incomplete data. For comparison, we report how two state-of-the-art registration algorithms perform on the same data sets.","Title: Real time landscape modelling and visualization\nYear: 2007\n\nAbstract: With the rapid development of information and communication technology and widely spreading of internet, digital landscape becomes a high topic recently. This paper presents a landscape modeling- and visualizationssystem. The first part of this paper focuses on the real time 3D-model- lingsprocess out of large point-clouds. Diverse experiments have been done on the reconstruction of various famous regions of Bavaria with tourist features. And the second part concentrates on the interactive online visualizationssystem for massive meshes. To enable an efficient interactive online visualization of these large meshes, we convert them firstly with a multi-resolution hierarchy, and then display them progressively. As a preprocessing for the inter-active rendering, we generate a hierarchical tree of bounding spheres from triangle meshes and write it to disk. It will be used for view frustum culling, backface culling and level-of-detail control. We use a recursive algorithm for display. And the traverse-depth in the tree is decided by the projected size of the current node on the screen. By an interactive rendering, once the user stops moving the mouse, the scene will be redrawn with successively smaller thresholds until a size of one pixel is reached.","Title: Navigating inner space: 3-D assistance for minimally invasive surgery\nYear: 2005\n\nAbstract: Since its inception about three decades ago, modern minimally invasive surgery has made huge advances in both technique and technology. However, the minimally invasive surgeon is still faced with daunting challenges in terms of visualization and hand-eye coordination.","Title: Estimation of spatio-temporal object properties for manipulation tasks from observation of humans\nYear: 2010\n\nAbstract: We propose a system for vision-based estimation of manipulation-relevant properties of objects in natural scenes based on observation of human actions. The system consists of an a-priori (Atlas) knowledge about known generic objects in the scene and classifies the scene into mission relevant objects and background geometry that is important only for collision avoidance. We present the object-centric structure of our system consisting of an Atlas representation and a Working Memory storing the current knowledge about the scene, the manipulated objects and actions applied to them in the local environment.We present experimental results how the system maintains the information in the database and we show the quality of the results that can be obtained with our system.","Title: A novel approach to automatic registration of point clouds\nYear: 2007\n\nAbstract: For the 3D reconstruction inside historic buildings, we need a marker-free automatic registration approach to align different views together, because GPS does not work indoors and markers are not allowed to paste on the walls. This paper presents an automatic matching process, which employs a novel algorithm, Dynamic Matching Tree technique, for a fast and stable coarse-matching to achieve the automatic pre-alignment of two point clouds and uses modified ICP to do a fine matching efficiently. The whole process can be divided in the following stages: preprocessing, 2-View matching and N-View matching. To validate our method, various experiments has been done on reconstruction of historic sites and industrial objects.","Title: Automation of Manual Tasks for Minimally Invasive Surgery\nYear: 2008\n\nAbstract: We have developed an experimental system for minimally invasive surgery providing force feedback and automation of recurring task. The system consists of four robotic arms, which can be equipped with either minimally invasive instruments or a stereo camera.The master console provides a stereo view of the field of operation and two input devices can feed back forces to the user. We have utilized this system to assess the possibility of automating difficult handling tasks like surgical knot tying. In order to achieve this, a novel approach for human-machine skill transfer was developed. It constitutes an extension to learning by demonstration, which is a well known paradigm of robotic learning.","Title: Vision-Based 3d Scene Analysis For Driver Assistance\nYear: 2005\n\nAbstract: We present a vision-based system for traffic sign detection and ego-motion estimation in road scenarios. The system is capable of autonomous scene reconstruction and classification. It is used to pre-select candidate surfaces in the vicinity of the road that should be inspected more closely by a sign recognition system.We compare two approaches based on a binocular and a monocular camera system, respectively. We discuss their advantages and disadvantages for applications in driver assistance systems.","Title: Fusion of laserscannner and video based lanemarking detection for robust lateral vehicle control and lane change maneuvers.\nYear: 2011\n\nAbstract: The knowledge about lanes and the exact position on the road is fundamental for many advanced driver assistance systems. In this paper, a novel iterative histogram based approach with occupancy grids for the detection of multiple lanes is proposed. In highway scenarios, our approach is highly suitable to determine the correct number of all existing lanes on the road. Additionally, the output of the laserscannner based lane detection is fused with a production-available vision based system. It is shown that both sensor systems perfectly complement each other to increase the robustness of a lane tracking system. The achieved accuracy of the fusion system, the laserscannner and video based system is evaluated with a highly accurate DGPS to investigate the performance with respect to lateral vehicle control applications.","Title: A dynamic 3D environmental model with real-time access functions for use in autonomous mobile robots\nYear: 1995\n\nAbstract: A model of the environment is a mandatory requirement for the autonomy of a mobile robot. In this paper, we present a framework for the prediction of expected sensor images on feature level, which is based on a-priori knowledge about the geometry of the environment. Our algorithm is capable to serve all distance and image measuring sensors typically found on mobile robots in real time. Fast prediction is achieved by using concepts from database technology and computer graphics. By incorporating differences between the expected and sensed image, the model can be adapted to changes and uncertainties in the environment. So the predicted features can be attributed with uncertainties to support and enhance the match process.","Title: Real-time 3D Surface Tracking and Its Applications\nYear: 2004\n\nAbstract: We present a general technique for directly estimating and tracking surfaces from a stream of rectified stereo pairs in real-time. These techniques are based on the iterative updating of surface representations directly from image information and use no disparity search except during initialization. We perform the tracking through an iteratively re-weighted least squares minimization wherein a mask is incorporated to increase robustness to occlusion. The algorithms are formulated for a general family of linear in parameters surface models and discussed for the cases of planar surfaces and tensor product surfaces. These algorithms have been implemented on standard hardware and run at or near frame rate, with accuracy on the order of 1/20 of a pixel. We discuss applications of the technique including mobile robot localization, general deforming surface tracking, and biometry of biological surfaces.","Title: Fast recovery of weakly textured surfaces from monocular image sequences\nYear: 2010\n\nAbstract: We present a method for vision-based recovery of threedimensional structures through simultaneous model reconstruction and camera position tracking from monocular images. Our approach does not rely on robust feature detecting schemes (such as SIFT, KLT etc.), but works directly on intensity values in the captured images. Thus, it is well-suited for reconstruction of surfaces that exhibit only minimal texture due to partial homogeneity of the surfaces. Our method is based on a well-known optimization technique, which has been implemented in an efficient yet flexible way, in order to achieve high performance while ensuring extensibility.","Title: Direct pose estimation with a monocular camera\nYear: 2008\n\nAbstract: We present a direct method to calculate a 6DoF pose change of a monocular camera for mobile navigation. The calculated pose is estimated up to a constant unknown scale parameter that is kept constant over the entire reconstruction process. This method allows a direct calculation of the metric position and rotation without any necessity to fuse the information in a probabilistic approach over longer frame sequence as it is the case in most currently used VSLAM approaches. The algorithm provides two novel aspects to the field of monocular navigation. It allows a direct pose estimation without any a-priori knowledge about the world directly from any two images and it provides a quality measure for the estimated motion parameters that allows to fuse the resulting information in Kalman Filters. We present the mathematical formulation of the approach together with experimental validation on real scene images.","Title: VICs: a modular vision-based HCI framework\nYear: 2003\n\nAbstract: Many Vision-Based Human-Computer Interaction (VBHCI) systems are based on the tracking of user actions. Examples include gaze-tracking, head-tracking, finger-tracking, and so forth. In this paper, we present a framework that employs no user-tracking; instead, all interface components continuously observe and react to changes within a local image neighborhood. More specifically, components expect a pre-defined sequence of visual events called Visual Interface Cues (VICs). VICs include color, texture, motion and geometric elements, arranged to maximize the veridicality of the resulting interface element. A component is executed when this stream of cues has been satisfied. We present a general architecture for an interface system operating under the VIC-Based HCI paradigm, and then focus specifically on an appearance-based system in which a Hidden Markov Model (HMM) is employed to learn the gesture dynamics. Our implementation of the system successfully recognizes a button-push with a 96% success rate. The system operates at frame-rate on standard PCs.","Title: Modeling kinematics of mobile C-arm and operating table as an integrated six degrees of freedom imaging system\nYear: 2010\n\nAbstract: Maneuvering mobile C-arms to a desired position and orientation during surgery is not only a routine surgical task, e.g. for C-arm repositioning, but also an indispensable step for advanced X-ray imaging techniques, e.g. parallax-free X-ray image stitching. Standard mobile C-arms have only five degrees of freedom (DOF), which definitely restricts their motions that have six DOF in 3D Cartesian space. In this paper, we enable the mobile C-arm to have six DOF relative to the patient's table by integrating a translational movement of the patient's table into the mobile C-arm kinematics. We present a novel method to model the kinematics of the mobile C-arm and operating table as an integrated 6DOF C-arm X-ray imaging system. Kinematic singularities of the 6DOF C-arm model are determined by analyzing its manipulator Jacobian matrix. Inverse kinematic analysis is employed in order to find the required joint values to move the C-arm into the desired position and orientation. Our proposed 6DOF C-arm modeling paves the way for advanced applications in the fields of surgical navigation and advanced X-ray imaging that require C-arms to be precisely positioned or repositioned relative to the patient's table with six DOF. In our implementation, we employ a visual planar marker pattern and a standard mobile C-arm augmented by a video camera in order to obtain a relationship between the C-arm system and the patient's table. C-arm repositioning experiments on phantom study demonstrate the practicality and accuracy of our developed 6DOF C-arm system, and show the improved accuracy of C-arm repositioning by using the 6DOF C-arm model over the 5DOF C-arm model.","Title: Real-time Image-based Localization for Hand-held 3D-modeling\nYear: 2010\n\nAbstract: We present a self-referencing hand-held scanning device for vision-based close-range 3D-modeling. Our approach replaces external\n global tracking devices with ego-motion estimation directly from the camera used for reconstruction. The system is capable\n of online estimation of the 6DoF pose on hand-held devices with high motion dynamics especially in rotational components.\n Inertial information supports directly the tracking process to allow for robust tracking and feature management in highly\n dynamic environments. We introduce a weighting function for landmarks that contribute to the pose estimation increasing the\n accuracy of the localization and filtering outliers in the tracking process. We validate our approach with experimental results\n showing the robustness and accuracy of the algorithm. We compare the results to external global referencing solutions used\n in current modeling systems.","Title: An efficient RANSAC for 3D object recognition in noisy and occluded scenes\nYear: 2010\n\nAbstract: In this paper, we present an efficient algorithm for 3D object recognition in presence of clutter and occlusions in noisy, sparse and unsegmented range data. The method uses a robust geometric descriptor, a hashing technique and an efficient RANSAC-like sampling strategy. We assume that each object is represented by a model consisting of a set of points with corresponding surface normals. Our method recognizes multiple model instances and estimates their position and orientation in the scene. The algorithm scales well with the number of models and its main procedure runs in linear time in the number of scene points. Moreover, the approach is conceptually simple and easy to implement. Tests on a variety of real data sets show that the proposed method performs well on noisy and cluttered scenes in which only small parts of the objects are visible.","Title: Toward a Fully Autonomous UAV: Research Platform for Indoor and Outdoor Urban Search and Rescue.\nYear: 2012\n\nAbstract: Urban search and rescue missions raise special requirements on robotic systems. Small aerial systems provide essential support to human task forces in situation assessment and surveillance. As external infrastructure for navigation and communication is usually not available, robotic systems must be able to operate autonomously. A limited payload of small aerial systems poses a great challenge to the system design. The optimal tradeoff between flight performance, sensors, and computing resources has to be found. Communication to external computers cannot be guaranteed; therefore, all processing and decision making has to be done on board. In this article, we present an unmanned aircraft system design fulfilling these requirements. The components of our system are structured into groups to encapsulate their functionality and interfaces. We use both laser and stereo vision odometry to enable seamless indoor and outdoor navigation. The odometry is fused with an inertial measurement unit in an extended Kalman filter. Navigation is supported by a module that recognizes known objects in the environment. A distributed computation approach is adopted to address the computational requirements of the used algorithms. The capabilities of the system are validated in flight experiments, using a quadrotor.","Title: DaVinci canvas: a telerobotic surgical system with integrated, robot-assisted, laparoscopic ultrasound capability.\nYear: 2005\n\nAbstract: We present daVinci Canvas: a telerobotic surgical system with integrated robot-assisted laparoscopic ultrasound capability. DaVinci Canvas consists of the integration of a rigid laparoscopic ultrasound probe with the daVinci robot, video tracking of ultrasound probe motions, endoscope and ultrasound calibration and registration, autonomous robot motions, and the display of registered 2D and 3D ultrasound images. Although we used laparoscopic liver cancer surgery as a focusing application, our broader aim was the development of a versatile system that would be useful for many procedures.","Title: Dynamic composition of tracking primitives for interactive vision-guided navigation\nYear: 2001\n\nAbstract: We present a system architecture for robust target following with a mobile robot. The system is based on tracking multiple cues in binocular stereo images using the XVision toolkit [1]. Fusion of complementary information in the images, including texture, color and depth, combined with a fast optimized processing reduces the possibility of loosing the tracked object in a dynamic scene with several moving targets on intersecting paths. The presented system is capable of detecting objects obstructing its way as well as gaps. It supports application in more cluttered terrain. where a wheel drive of mobile robot cannot take the same path as a walking person. We describe the basic principles of the fast feature extraction and tracking in the luminance, chrominance and disparity domain. The optimized tracking algorithms compensate for illumination variations and perspective distortions as already presented in our previous publications about the XVision system.","Title: Epipolar-Based Stereo Tracking Without Explicit 3D Reconstruction\nYear: 2010\n\nAbstract: We present a general framework for tracking image regions in two views simultaneously based on sum-of-squared differences (SSD) minimization. Our method allows for motion models up to affine transformations. Contrary to earlier approaches, we incorporate the well-known epipolar constraints directly into the SSD optimization process. Since the epipolar geometry can be computed from the image directly, no prior calibration is necessary. Our algorithm has been tested in different applications including camera localization, wide-baseline stereo, object tracking and medical imaging. We show experimental results on robustness and accuracy compared to the known ground truth given by a conventional tracking device.","Title: Deformable 3D Shape Registration Based on Local Similarity Transforms.\nYear: 2011\n\nAbstract: In this paper, a new method for deformable 3D shape registration is proposed. The algorithm computes shape transitions based on local similarity transforms which allows to model not only as-rigid-as-possible deformations but also local and global scale. We formulate an ordinary differential equation (ODE) which describes the transition of a source shape towards a target shape. We assume that both shapes are roughly pre-aligned (e. g., frames of a motion sequence). The ODE consists of two terms. The first one causes the deformation by pulling the source shape points towards corresponding points on the target shape. Initial correspondences are estimated by closest-point search and then refined by an efficient smoothing scheme. The second term regularizes the deformation by drawing the points towards locally defined rest positions. These are given by the optimal similarity transform which matches the initial (undeformed) neighborhood of a source point to its current (deformed) neighborhood. The proposed ODE allows for a very efficient explicit numerical integration. This avoids the repeated solution of large linear systems usually done when solving the registration problem within general-purpose non-linear optimization frameworks. We experimentally validate the proposed method on a variety of real data and perform a comparison with several state-of-the-art approaches.","Title: Identification of 3D Reference Structures for Video-Based Localization\nYear: 1998\n\nAbstract: The bootstrap--problem of self--localization in indoor environments is a demandingtask for initial localization and topological navigation. The ability to determinethe position in an a priori known or already explored environment allows unsuperviseduse of mobile robots in environments such as private households. Thispaper presents our approach to identify a given set of known reference structuresin a three--dimensional map of the local environment. This map is constructedfrom the data...","Title: Robust Feature Correspondences For Vision-Based Navigation With Slow Frame-Rate Cameras\nYear: 2006\n\nAbstract: We propose a vision-based inertial system that overcomes the problems associated with slow update rates in navigation systems based on high-resolution cameras. Due to bandwidth limitations in current camera interfaces, like Firewire or USB, an increase in the camera resolution results in a drop of the effective frame-rate from the sensor. This increases the correspondence problem for point features in consecutive images due to significant motion of the features. We solve the correspondence problem for very significant motion of point features between consecutive images by analyzing the motion blur to estimate the current motion parameters.The proposed algorithm can be used to track the position of point features in video images originating from slow frame-rate cameras. The system is validated on real images from a camera moved by a mobile system, but it can be used for any type of motion ranging from flying systems to mobile robots operating in outdoor or indoor environments.","Title: Scale-invariant registration of monocular endoscopic images to CT-scans for sinus surgery.\nYear: 2005\n\nAbstract: In this paper, we present a novel method for intra-operative registration directly from monocular endoscopic images. This technique has the potential to provide a more accurate surface registration at the surgical site than existing methods. It can operate autonomously from as few as two images and can be particularly useful in revision cases where surgical landmarks may be absent. A by-product of video registration is an estimate of the local surface structure of the anatomy, thus providing the opportunity to dynamically update anatomical models as the surgery progresses.","Title: Recent Methods for Image-Based Modeling and Rendering\nYear: 2003\n\nAbstract: A long-standing goal in image-based modeling and rendering is to capture a scene fromcamera images and construct a sufficient model to allow photo-realistic rendering of new views.With the confluence of computer graphics and vision, the combination of research on recoveringgeometric structure from uncalibrated cameras with modeling and rendering has yieldednumerous new methods. Yet, many challenging issues remain to be addressed before asufficiently general and robust system could be built to (for instance) allow an average user tomodel their home and garden from camcorder video. This tutorial aims to give researchers andstudents in computer graphics a working knowledge of relevant theory and techniques coveringthe steps from real-time vision for tracking and the capture of scene geometry and appearance, tothe efficient representation and real-time rendering of image-based models. It also includeshands-on demos of real-time visual tracking, modeling and rendering systems.","Title: VICs: A modular HCI framework using spatiotemporal dynamics\nYear: 2004\n\nAbstract: Many vision-based human-computer interaction systems are based on the tracking of user actions. Examples include gaze tracking, head tracking, finger tracking, etc. In this paper, we present a framework that employs no user tracking; instead, all interface components continuously observe and react to changes within a local neighborhood. More specifically, components expect a predefined sequence of visual events called visual interface cues (VICs). VICs include color, texture, motion, and geometric elements, arranged to maximize the veridicality of the resulting interface element. A component is executed when this stream of cues has been satisfied. We present a general architecture for an interface system operating under the VIC-based HCI paradigm and then focus specifically on an appearance-based system in which a hidden Markov model (HMM) is employed to learn the gesture dynamics. Our implementation of the system successfully recognizes a button push with a 96% success rate.","Title: Dynamic Augmented Reality For Sensory Substitution In Robot-Assisted Surgical Systems\nYear: 2006\n\nAbstract: Teleoperated robot-assisted surgical systems provide surgeons with improved precision, dexterity, and visualization over traditional minimally invasive surgery. The addition of haptic (force and/or tactile) feedback has been proposed as a way to further enhance the performance of these systems. However, due to limitations in sensing and control technologies, implementing direct haptic feedback to the surgeon's hands remains impractical for clinical application. A new, intuitive augmented reality system for presentation of force information through sensory substitution has been developed and evaluated. The augmented reality system consists or force-sensing robotic instruments, a kinematic tool tracker, and a graphic display that overlays a visual representation of force levels on top of the moving instrument lips. The system is integrated with the da Vinci Surgical System (Intuitive Surgical, Inc.) and tested by several users in a phantom knot tying task. The augmented reality system decreases the number of broken sutures, decreases the number of loose knots, and results in more consistent application of forces.","Title: Adaptive and generic corner detection based on the accelerated segment test\nYear: 2010\n\nAbstract: The efficient detection of interesting features is a crucial step for various tasks in Computer Vision. Corners are favored cues due to their two dimensional constraint and fast algorithms to detect them. Recently, a novel corner detection approach, FAST, has been presentedwhich outperforms previous algorithms in both computational performance and repeatability. We will show how the accelerated segment test, which underlies FAST, can be significantly improved by making it more generic while increasing its performance.We do so by finding the optimal decision tree in an extended configuration space, and demonstrating how specialized trees can be combined to yield an adaptive and generic accelerated segment test. The resulting method provides high performance for arbitrary environments and so unlike FAST does not have to be adapted to a specific scene structure. We will also discuss how different test patterns affect the corner response of the accelerated segment test.","Title: Illumination-invariant image-based novelty detection in a cognitive mobile robot's environment\nYear: 2010\n\nAbstract: Image-based scene representations enable a mobile robot to make a realistic prediction of its environment. Hence, it is able to rapidly detect changes in its surroundings by comparing a virtual image generated from previously acquired reference images and its current observation. This facilitates attentional control to novel events. However, illumination effects can impair attentional control if the robot does not take them into account. To address this issue, we present in this paper an approach for the acquisition of illumination-invariant scene representations. Using multiple spatial image sequences which are captured under varying illumination conditions the robot computes an illumination-invariant image-based environment model. With this representation and statistical models about the illumination behavior, the robot is able to robustly detect texture changes in its environment under different lighting. Experimental results show high-quality images which are free of illumination effects as well as more robust novelty detection compared to state-of-the-art methods.","Title: Vision Based Control of Mobile Robots\nYear: 2001\n\nAbstract: Abstract: This paper presents an approach for direct controlof a mobile robot to keep it on a pre-taught path basedsolely on the perception from a monocular CCD camera.In particular, we present a novel vision-basedcontrol algorithm for mobile systems equipped with aconventional camera and a pan-tilt head or with anomnidirection camera. This algorithm avoids numericalinstabilities of previously reported approaches. Theexperimental performance of the method as well as itspractical limitations are...","Title: Rgb-D Sensor Data Correction And Enhancement By Introduction Of An Additional Rgb View\nYear: 2013\n\nAbstract: RGB-D sensors are becoming more and more vital to robotics. Sensors such as the Microsoft Kinect and time of flight cameras provide 3D colored point-clouds in real time can play a crucial role in Robot Vision. However these sensors suffer from precision deficiencies, and often the density of the point-clouds they provide is insufficient. In this paper, we present a multi-camera system for correction and enhancement of the data acquired from an RGB-D sensor. Our system consists of two sensors, the RGB-D sensor (main sensor) and a regular RGB camera (auxiliary sensor). We perform the correction and the enhancement of the data acquired from the RGB-D sensor by placing the auxiliary sensor in a close proximity to the target object and taking advantage of the established epipolar geometry. We have managed to reduce the relative error of the raw point-cloud from a Microsoft Kinect RGB-D sensor by 74.5% and increase its density up to 2.5 times.","Title: Stochastic Optimization for Rigid Point Set Registration\nYear: 2009\n\nAbstract: In this paper we propose a new method for pairwise rigid point set registration. We pay special attention to noise robustness, outlier resistance and global optimal alignment. The problem of registering two point clouds in space is converted to a minimization of a nonlinear cost function. We propose a cost function that aims to reduce the impact of noise and outliers. Its definition is based on the input point sets and is directly related to the quality of a concrete rigid transform between them. In order to achieve a global optimal registration, without the need of a good initial alignment, we develop a new stochastic approach for global minimization. Tests on a variety of point sets show that the proposed registration algorithm performs very well on noisy, outlier corrupted and incomplete data.","Title: Rigid 3D geometry matching for grasping of known objects in cluttered scenes\nYear: 2012\n\nAbstract: In this paper, we present an efficient 3D object recognition and pose estimation approach for grasping procedures in cluttered and occluded environments. In contrast to common appearance-based approaches, we rely solely on 3D geometry information. Our method is based on a robust geometric descriptor, a hashing technique and an efficient, localized RANSAC-like sampling strategy. We assume that each object is represented by a model consisting of a set of points with corresponding surface normals. Our method simultaneously recognizes multiple model instances and estimates their pose in the scene. A variety of tests shows that the proposed method performs well on noisy, cluttered and unsegmented range scans in which only small parts of the objects are visible. The main procedure of the algorithm has a linear time complexity resulting in a high recognition speed which allows a direct integration of the method into a continuous manipulation task. The experimental validation with a seven-degree-of-freedom Cartesian impedance controlled robot shows how the method can be used for grasping objects from a complex random stack. This application demonstrates how the integration of computer vision and soft-robotics leads to a robotic system capable of acting in unstructured and occluded environments.","Title: A biologically inspired navigation concept based on the Landmark-Tree map for efficient long-distance robot navigation.\nYear: 2014\n\nAbstract: Map-based navigation is a crucial task for any mobile robot. Usually, in an unknown environment, this problem is addressed by applying Simultaneous Localization and Mapping based on metric grid-maps. However, such maps are in general rather computational expensive and do not scale well. Insects are able to cover large distances and reliably find back to their nests, although they are quite limited in their resources. Inspired by theories on insect navigation, we developed a data structure which is highly scalable and efficiently adapts to the available memory during run-time. Positions in space are memorized as snapshots, which are unique configurations of landmarks. Unlike conventional snapshot or visual map approaches, we do not simply store the landmarks as a set, but we arrange them in a tree-like structure according to the relevance of their information. The resulting navigation solely relies on the direction measurements of arbitrary landmarks. In this work, we present the concept of the Landmark-Tree (LT) map and apply it to a mobile platform equipped with an omnidirectional camera. We verify the reliability and robustness of the LT-map concept in simulations as well as by experiments with the robotic platform.","Title: A Practical Paradigm and Platform for Video-Based Human-Computer Interaction\nYear: 2008\n\nAbstract: New technologies that use multimodal input, human experience, and modern hardware's full computational power could mitigate current limitations in human-computer interaction. The 4D Touchpad, a video-based interaction platform, makes robust, natural interaction between humans and computers possible.","Title: 3D reconstruction of dynamic scenes from two asynchronous video-streams\nYear: 2014\n\nAbstract: We present an algorithm for reconstruction of dynamic scenes from a video input of an asynchronous stereo-pair. Our method presumes that the timestamps of the frame acquisitions and the intrinsic parameters of the stereo cameras are known, as well as, that the extrinsic parameters can be estimated from static regions of the scene. It computes the 3D trajectory of each individual point by modeling its motion parameters. Our algorithm requires in addition to the two asynchronous images from the camera pair, two additional images from one of the cameras for its processing. Since dynamic scene elements cause wrong reconstructions, here we introduce a two stage process in which the directions of the possible motion components are estimated prior to the 3D pose estimation of the corresponding point.","Title: Dense and Deformable Motion Extraction in Dynamic Scenes Based on Hierarchical MRF Optimization in RGB-D Images\nYear: 2015\n\nAbstract: We present a novel hierarchical MRFs optimization method for dense and deformable motion extraction in dynamic scenes. In particular, this hierarchical MRFs structure consists of two layers, the segmentation and the correspondence layer. Firstly, dynamic RGB-D foreground data is segmented through a pixel-level MRF in the segmentation layer. Subsequently, the extracted foreground data is transformed into a 3D point-level MRF in the correspondence layer. A new surface descriptor named deformable color and shape histogram is proposed. It is combined with photometric and geometric features to represent a deformable surface. Finally, the dynamic scene motion is retrieved from correspondences established in the image sequence. Discrete optimization schemes are used for the binary classification and multi-labeling problems. We provide an RGB-D dataset of dynamic scenes, which involves different motion patterns and surface properties of foreground objects. The effectiveness and efficiency of our proposed approach for high accurate foreground segmentation and motion extraction is validated in experiments.","Title: Local reference filter for life-long vision aided inertial navigation\nYear: 2014\n\nAbstract: Filter based system state estimation is widely used for hard-realtime applications. In long-term filter operation the estimation of unobservable system states can lead to numerical instability due to unbounded state uncertainties. We introduce a filter concept that estimates system states in respect to changing local references instead of one global reference. In this way unbounded state covariances can be reset in a consistent way. We show how local reference (LR) filtering can be integrated into filter prediction to be used in square root filter implementations. The concept of LR-filtering is applied to the problem of vision aided inertial navigation (LR-INS). The results of a simulated 24 h quadrotor flight using the LR-INS demonstrate longterm filter stability. Real quadrotor flight experiments show the usability of the LR-INS for a highly dynamic system with limited computational resources.","Title: A framework for dynamic sensory substitution\nYear: 2014\n\nAbstract: In this paper we present a framework for dynamic substitution of different sensory modalities with existing physical sensors. Our system is capable of finding the most optimal set of mathematical and physical transformations between two modalities of physical and virtual sensors. It allows a creation of new virtual sensors from given set of physical sensors. The virtual sensing may extend to new sensing modalities for which no direct physical sensors exist. The framework optimizes for a minimal error and optimal observation in the resulting fusion. It is processing the chain for a given spatial measurement and measurement range. The framework is capable of increasing the reliability of acquired data in multi-sensor systems by being able to asses the amount of accumulated errors. We give two examples of real-world applications of this framework in robotic environments.","Title: Stereo-based obstacle avoidance in indoor environments with active sensor re-calibration\nYear: 2002\n\nAbstract: We present a stereo-based obstacle avoidance sys- tem for mobile vehicles. The system operates in three steps. First, it models the surface geometry of support- ing surface and removes the supporting surface from the scene. Next, it segments the remaining stereo dis- parities into connected components in image and dis- parity space. Finally, it projects the resulting con- nected components onto the supporting surface and plans a path around them. One interesting aspect of this system is that it can detect both positive and \\neg- ative\" obstacles (e.g. stairways) in its path. The algorithms we have developed have been imple- mented on a mobile robot equipped with a real-time stereo system. We present experimental results on indoor environments with planar supporting surfaces that show the algorithms to be both fast and robust.","Title: Scene classification from dense disparity maps in indoor environments\nYear: 2002\n\nAbstract: We present our approach for scene classification in dense disparity maps from a binocular stereo system. The classification result is used for tracking and navigation purposes. The presented system is capable of foreground-background separation classifying room structures. The 3D model of the scene is derived directly from the disparity image. This approach is used for initial target selection and scene classification in mobile navigation. It is used on our mobile system for target tracking, but can also be used for localization as described in this paper. We describe the basic principles of our object detection and classification using disparity information from a binocular stereo system. The theoretical derivation is supported by results from the binocular stereo sensor system on our mobile robot.","Title: Advances in computational stereo\nYear: 2003\n\nAbstract: Extraction of three-dimensional structure of a scene from stereo images is a problem that has been studied by the computer vision community for decades. Early work focused on the fundamentals of image correspondence and stereo geometry. Stereo research has matured significantly throughout the years and many advances in computational stereo continue to be made, allowing stereo to be applied to new and more demanding problems. In this paper, we review recent advances in computational stereo, focusing primarily on three important topics: correspondence methods, methods for occlusion, and real-time implementations. Throughout, we present tables that summarize and draw distinctions among key ideas and approaches. Where available, we provide comparative analyses and we make suggestions for analyses yet to be done.","Title: Optimal landmark configuration for vision-based control of mobile robots\nYear: 2003\n\nAbstract: Abstract, We analyze the problem of finding the optimal placement of tracked primitives for robust vision-based con-trol of a mobile robot. The analysis evaluates the properties of the Image Jacobian matrix, used for direct generation of the control signals from the error signal in the image, and the accuracy of the underlying sensor system. The analysis is then used to select optimal tracking primitives that ensure good observability and controllability of the mobile system for a variety of sensor system configurations. The theoretical results are validated with our mobile robot for system configurations that use standard video cameras mounted on a pan-tilt head and catadioptric systems.","Title: Direct plane tracking in stereo images for mobile navigation\nYear: 2003\n\nAbstract: We present a novel plane tracking algorithm based on the direct update of surface parameters from two stereo images. The plane tracking algorithm is posed as an optimization problem, and maintains an iteratively re-weighted least squares approximation of the plane's orientation using direct pixel measurements. To facilitate autonomous operation, we include an algorithm for robust detection of significant planes in the environment. The algorithms have been implemented in a robot navigation system.","Title: V-GPS - image-based control for 3D guidance systems\nYear: 2003\n\nAbstract: We present our approach for pose verification with monocular cameras in 3-dimensional space based on the image-based control paradigm. We describe the extensions to our previous control system for mobile navigation that allow us to estimate the complete set of pose parameters in space. The major contribution of this approach is a sensor- independent formulation of the image formation that allows a flexible configuration with a variety of sensor systems including standard cameras, omnidirectional cameras and laser systems. Our second contribution is a way to re- initialize the tracked landmarks during a multi-segment navigation in applications with significant deviations from the pre-taught trajectory as it is the case for handheld systems and flying robots. The presented system can be used as a guidance system for visitors. The localization is based on known landmarks that are in our case natural landmarks in the environment. These landmarks correspond to the satellites of a GPS system. We call it V-GPS (vision-based GPS) because of this similarity in the concept. A camera carried by a person allows to navigate along pre-specified paths through environments, like galleries, hospitals, parks, and other public places.","Title: Scale-invariant registration of monocular stereo images to 3D surface models\nYear: 2004\n\nAbstract: We present an approach for scale recovery from monocular stereo images of an endoscopic camera with simul- taneous registration to dense 3D surface models. We assume the camera motion to be unknown or at least uncertain. An example application is the registration of endoscope images to pre-operative CT scans that allows instrument navigation during surgical procedures. The application field is not restricted to the medical field. It can be extended to registration of monocular video images to laser-based surface reconstructions in, e.g., mobile navigation area or to autonomous aircraft navigation from topological surveys. A novel way for depth estimation from arbitrary camera motion is presented. In this paper, we focus on the robust initialization of the system and on the scale recovery for the reconstructed 3D point clouds with accurate registration to the candidate surfaces extracted from the CT data. We provide experimen- tal validation of the algorithm with data obtained from our experiments with a phantom skull. I. MOTIVATION In endonasal surgery and other medical minimally inva- sive procedures, an endoscopic camera is used to provide information about the current instrument location to the surgeon. Since some sinus surgical procedures are close to optic nerves, the eyes, and the brain, surgeons require the best possible information during the surgery to guide the surgical instruments inside of the nasal cavities (Fig. 1). Fig. 1. Endoscopic inspection of the nasal Sinus cavities depicting the limited information provided to the surgeon. The necessary information is supplied primarily through the endoscope requiring from the surgeon a good knowl- edge of anatomy. Computer Integrated Surgery techniques has been em- ployed in the endonasal approach. Image-guided surgery system (IGS), that integrates pre-operative medical images with the endoscope information, supplies valuable infor- mation beyond what the endoscope alone can provide. In IGS, data from a preoperative CT scan is downloaded into the computer in the operating room and localizers are attached to surgical instruments. Once the patient's head position is registered, the software provides the surgeon with the 3D location of the tip of the instrument visualized relative to the pre-operative CT-scan. The current frame- less registration method for IGS is based on anatomic fiducial points or based on contour mapping (6). The accuracy of registration is crucial for any image-guided system. If registration errors occur, the localization ac- curacy suffers. Therefore, the operating surgeon must re- align the registration at several points in the operative field throughout the procedure.","Title: Perception-based motion planning for indoor exploration\nYear: 1999\n\nAbstract: This paper proposes an approach for motion planning in indoor environments based on incomplete and uncertain information from a line-based binocular stereo system. The primary goal of the planning process is to plan an optimal path through an unknown or partially known environment, depending on the information gained from exploration and the current mission goal. This paper presents an adaptable motion planner that supports sensor-based map construction, object recognition and navigation in an unknown environment while carrying out a mission. Also presented are some preliminary experimental results that demonstrate the utility of the approach","Title: Visual homing and surprise detection for cognitive mobile robots using image-based environment representations\nYear: 2009\n\nAbstract: One important feature of a cognitive system is to perceive and understand its environment and to adapt its actions to changes and unforeseen situations. In this paper, we propose a scheme for visual surprise detection in cognitive mobile robots. With the robot's observation and a set of reference images previously acquired near its current viewpoint, a pixel-wise surprise trigger is computed using Bayesian probabilistic inference techniques. With appropriate mathematical approximations this algorithm can be implemented on modern graphics hardware which nearly allows for real-time surprise detection. In order to refer to prior observations, a mobile robot has to be able to re-localize itself with respect to its environment. Thus, we also present two online image-based homing algorithms which both facilitate the computation of location-independent surprise triggers. Experiments show acceptable results in terms of robust and fast detection of unexpected changes in the environment.","Title: State estimation for highly dynamic flying systems using key frame odometry with varying time delays\nYear: 2012\n\nAbstract: System state estimation is an essential part for robot navigation and control. A combination of Inertial Navigation Systems (INS) and further exteroceptive sensors such as cameras or laser scanners is widely used. On small robotic systems with limitations in payload, power consumption and computational resources the processing of exteroceptive sensor data often introduces time delays which have to be considered in the sensor data fusion process. These time delays are especially critical in the estimation of system velocity. In this paper we present a state estimation framework fusing an INS with time delayed, relative exteroceptive sensor measurements. We evaluate its performance for a highly dynamic flight system trajectory including a flip. The evolution of velocity and position errors for varying measurement frequencies from 15Hz to 1Hz and time delays up to 1s is shown in Monte Carlo simulations. The filter algorithm with key frame based odometry permits an optimal, local drift free navigation while still being computationally tractable on small onboard computers. Finally, we present the results of the algorithm applied to a real quadrotor by flying from inside a house out through the window.","Title: Efficient occupancy grid computation on the GPU with lidar and radar for road boundary detection\nYear: 2010\n\nAbstract: Accurate maps of the static environment are essential for many advanced driver-assistance systems. In this paper a new method for the fast computation of occupancy grid maps with laser range-finders and radar sensors is proposed. The approach utilizes the Graphics Processing Unit to overcome the limitations of classical occupancy grid computation in automotive environments. It is possible to generate highly accurate grid maps in just a few milliseconds without the loss of sensor precision. Moreover, in the case of a lower resolution radar sensor it is shown that it is suitable to apply super-resolution algorithms to achieve the accuracy of a higher resolution laser-scanner. Finally, a novel histogram based approach for road boundary detection with lidar and radar sensors is presented.","Title: Path optimization for abstractly represented tasks with respect to efficient control\nYear: 2013\n\nAbstract: In order to be able to replace a human operator, a robotic manipulation system needs to deal with a variety of possible actions. These actions may be more or less constrained in their motion profile and in the accuracy of the transport goals. The robotic system can make use of some of this variation to simplify the control to improve the efficiency of the generated motion. Nevertheless, the human's intention behind the manipulation may not change. We introduce the Elastic Power Path to optimize paths with respect to efficient control in the context of abstractly represented tasks. Our experiments show, that the proposed Elastic Power Path is an efficient method to achieve this aim. The magnitude and the number of turnarounds of the accelerations along the path are significantly reduced.","Title: Analysis of manipulator structures under joint-failure with respect to efficient control in task-specific contexts\nYear: 2013\n\nAbstract: Robots are meanwhile able to perform several tasks. But what happens, if one or multiple of the robot's joints fail? Is the robot still able to perform the required tasks? Which capabilities of the robot get limited and which ones are lost? We propose an analysis of manipulator structures for the comparison of a robot's capabilities with respect to efficient control. The comparison is processed (1) within a robot in the case of joint failures and (2) between robots with or without joint failures. It is important, that the analysis can be processed independently of the structure of the manipulator. The results have to be comparable between different manipulator structures. Therefore, an abstract representation of the robot's dynamic capabilities is necessary. We introduce the Maneuverability Volume and the Spinning Pencil for this purpose. The Maneuverability Volume shows, how efficiently the end-effector can be moved to any other position. The Spinning Pencil reflects the robot's capability to change its end-effector orientation efficiently. Our experiments show not only the different capabilities of two manipulator structures, but also the change of the capabilities if one or multiple joints fail.","Title: Monocular ego-motion estimation with a compact omnidirectional camera\nYear: 2010\n\nAbstract: We present a generalization of the Koenderink-van Doorn (KvD) algorithm that allows robust monocular localization with large motion between the camera frames for a wide range of optical systems including omnidirectional systems and standard perspective cameras. The KvD algorithm estimates simultaneously ego-motion parameters, i.e. rotation, translation, and object distances in an iterative way. However due to the linearization of the rotational component of optic flow, the original algorithm fails for larger rotations. We present a generalization of the algorithm to arbitrary rotations that is especially suited for omnidirectional cameras where features can be tracked for long sequences. This reduces the need for vector summation of several individual motion estimates that leads to accumulation of odometry errors. The significant improvement in the performance of the proposed generalized algorithm compared to the original KvD implementation is validated using simulated data. The algorithm is also tested in a real-world experiment with ground-truth data obtained from an external tracking system. The experiment was carried out using a novel compact omnidirectional camera that is designed for small aerial vehicles. It consists of an off-the-shelf webcam that is combined with a reflective surface machined into acrylic glass.","Title: Sparse keypoint models for 6D object pose estimation\nYear: 2013\n\nAbstract: In this paper, we present an approach to generate sparse object models for keypoint-based 6D object pose estimation. Keypoint-based object models usually consist of thousands of keypoints. Our approach generates sparse models by identifying and removing keypoints that are not relevant to the object localization. It applies data association to detect duplicate keypoints and applies statistical analysis to identify keypoints that have not been detected reliably during model generation. Our approach furthermore ensures that keypoints are well distributed across the volume of the object model. We evaluated our approach using a SIFT-based 6D object localization system on the basis of real world datasets. In our experiments, we achieved a reduction of the model sizes to approximately 1% of the original model size without a substantial loss of localization performance.","Title: Spatio-temporal prediction of collision candidates for static and dynamic objects in monocular image sequences\nYear: 2013\n\nAbstract: This paper presents a novel approach for reactive obstacle avoidance for static and dynamic objects using monocular image sequences. A sparse motion field is calculated by tracking point features using the Kanade-Lucas-Tomasi method. The rotational component of this sparse optical flow due to ego motion of the camera is compensated using motion parameters estimated directly from the images. A robust method for detection of static and dynamic objects in the scene is applied to identify collision candidates. The approach operates entirely in the image space of a monocular camera and does not require any extrinsic information about the configuration of the sensor or speed of the camera. The system prioritizes the detected collision candidates by their time to collision. Additionally, the spatial distribution of the candidates is calculated for non-degenerated conditions. We present the mathematical framework and the experimental validation of the suggested approach on simulated and real-world data.","Title: Motion Estimated-Compensated Reconstruction With Preserved-Features In Free-Breathing Cardiac Mri\nYear: 2016\n\nAbstract: To develop an efficient motion-compensated reconstruction technique for free-breathing cardiac magnetic resonance imaging (MRI) that allows high-quality images to be reconstructed from multiple undersampled single-shot acquisitions. The proposed method is a joint image reconstruction and motion correction method consisting of several steps, including a non-rigid motion extraction and a motion-compensated reconstruction. The reconstruction includes a denoising with the Beltrami regularization, which offers an ideal compromise between feature preservation and staircasing reduction. Results were assessed in simulation, phantom and volunteer experiments. The proposed joint image reconstruction and motion correction method exhibits visible quality improvement over previous methods while reconstructing sharper edges. Moreover, when the acceleration factor increases, standard methods show blurry results while the proposed method preserves image quality. The method was applied to free-breathing single-shot cardiac MRI, successfully achieving high image quality and higher spatial resolution than conventional segmented methods, with the potential to offer high-quality delayed enhancement scans in challenging patients.","Title: Effectiveness of Grasp Attributes and Motion-Constraints for Fine-Grained Recognition of Object Manipulation Actions.\nYear: 2016\n\nAbstract: In this work, we consider the problem of recognition of object manipulation actions. This is a challenging task for real everyday actions, as the same object can be grasped and moved in different ways depending on its functions and geometric constraints of the task. We propose to leverage grasp and motion-constraints information, using a suitable representation, to recognize and understand action intention with different objects. We also provide an extensive experimental evaluation on the recent Yale Human Grasping dataset consisting of large set of 455 manipulation actions. The evaluation involves a) Different contemporary multi-class classifiers, and binary classifiers with one-vs-one multi-class voting scheme, and b) Differential comparisons results based on subsets of attributes involving information of grasp and motion-constraints. Our results clearly demonstrate the usefulness of grasp characteristics and motion-constraints, to understand actions intended with an object.","Title: Reactive Obstacle Avoidance for Highly Maneuverable Vehicles Based on a Two-Stage Optical Flow Clustering.\nYear: 2017\n\nAbstract: This paper proposes a reactive obstacle avoidance approach based solely on image data from a monocular camera stream. By clustering and analyzing the optical flow, this approach is able to identify potential collisions with dynamic obstacles. Epipolar geometry is exploited to derive velocity commands that ensure a collision-free path for a highly maneuverable autonomous vehicle via a real-time opt...","Title: Monocular Navigation in Large Scale Dynamic Environments.\nYear: 2017\n\nAbstract: present a processing technique for a robust reconstruction of motion properties for single points in large scale, dynamic environments. assume that the acquisition camera is moving and that there are other independently moving agents in a large environment, like road scenarios. The separation of direction and magnitude of the reconstructed motion allows for robust reconstruction of the dynamic state of the objects in situations, where conventional binocular systems fail due to a small signal (disparity) from the images due to a constant detection error, and where structure from motion approaches fail due to unobserved motion of other agents between the camera frames. We present the mathematical framework and the sensitivity analysis for the resulting system.","Title: A vectorized Levenberg-Marquardt model fitting algorithm for efficient post-processing of cardiac T1 mapping MRI.\nYear: 2018\n\nAbstract: We have proposed a vectorized curve fitting algorithm allowing spatial regularization, which could improve the robustness of the curve fitting, especially for myocardial T mapping with SR sequences.","Title: Interaction-Aware Probabilistic Behavior Prediction In Urban Environments\nYear: 2018\n\nAbstract: Planning for autonomous driving in complex, urban scenarios requires accurate prediction of the trajectories of surrounding traffic participants. Their future behavior depends on their route intentions, the road-geometry, traffic rules and mutual interaction, resulting in interdependencies between their trajectories. We present a probabilistic prediction framework based on a dynamic Bayesian network, which represents the state of the complete scene including all agents and respects the aforementioned dependencies. We propose Markovian, context-dependent motion models to define the interaction-aware behavior of drivers. At first, the state of the dynamic Bayesian network is estimated over time by tracking the single agents via sequential Monte Carlo inference. Secondly, we perform a probabilistic forward simulation of the network's estimated belief state to generate the different combinatorial scene developments. This provides the corresponding trajectories for the set of possible, future scenes. Our framework can handle various road layouts and number of traffic participants. We evaluate the approach in online simulations and real-world scenarios. It is shown that our interaction-aware prediction outperforms interaction-unaware physics-and map-based approaches.","Title: Classifying Object Manipulation Actions based on Grasp-types and Motion-Constraints.\nYear: 2018\n\nAbstract: In this work, we address a challenging problem of fine-grained and coarse-grained recognition of object manipulation actions. Due to the variations in geometrical and motion constraints, there are different manipulations actions possible to perform different sets of actions with an object. Also, there are subtle movements involved to complete most of object manipulation actions. This makes the task of object manipulation action recognition difficult with only just the motion information. We propose to use grasp and motion-constraints information to recognise and understand action intention with different objects. We also provide an extensive experimental evaluation on the recent Yale Human Grasping dataset consisting of large set of 455 manipulation actions. The evaluation involves a) Different contemporary multi-class classifiers, and binary classifiers with one-vs-one multi- class voting scheme, b) Differential comparisons results based on subsets of attributes involving information of grasp and motion-constraints, c) Fine-grained and Coarse-grained object manipulation action recognition based on fine-grained as well as coarse-grained grasp type information, and d) Comparison between Instance level and Sequence level modeling of object manipulation actions. Our results justifies the efficacy of grasp attributes for the task of fine-grained and coarse-grained object manipulation action recognition.","Title: Isotropic Reconstruction of MR Images Using 3D Patch-Based Self-Similarity Learning.\nYear: 2018\n\nAbstract: Isotropic three-dimensional (3D) acquisition is a challenging task in magnetic resonance imaging (MRI). Particularly in cardiac MRI, due to hardware and time limitations, current 3D acquisitions are limited by low-resolution, especially in the through-plane direction, leading to poor image quality in that dimension. To overcome this problem, super-resolution (SR) techniques have been proposed to r...","Title: GPU implementation of Levenberg-Marquardt optimization for Ti mapping\nYear: 2017\n\nAbstract: T\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n mapping is an emerging MRI research tool to characterize diseased myocardial tissue. The T\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</sub>\n map is generated by fitting an exponential relaxation curve to the acquired image data. Levenberg-Marquardt algorithm is a standard way to solve this nonlinear curve fitting problem. However, the execution on the standard CPU can be time-consuming and incompatible with clinical routine. In this paper, a GPU implementation is performed to reduce the computation time of the standard T\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n mapping. In addition, a new vectorized approach is proposed to include spatial regularization in the curve fitting process to improve the robustness. The GPU implementation is validated on NVIDIA K42000 GPU using cardiac T1 data from 16 volunteers. The computation time shows significant decrease in both pixel-wise and vectorized curve fitting. The pixel-wise curve fitting is accelerated by a factor of 30+ compared to the standard sequential C code and the vectorized curve fitting is improved by a factor of 47 and 38 for 3-parameter and 2-parameter curve fitting compared to the Matlab code.","Title: Context-Aware 3D Visualization of the Dynamic Environment\nYear: 2019\n\nAbstract: We present a graphical interface that provides context-dependent information about possible interactions with a complex cluttered environment, which can be used as a video overlay system in Head Mounted Devices (HMDs) in Augmented Reality applications. The system identifies task relevant objects in a cluttered scene, learns the typical interaction patterns with them in a teaching phase, and supports the user with information about the object functionality and handling in the interaction phase. The underlying systen is capable of identification of objects in cluttered environment, providing information about possible task-dependent grasps, tracking object motion with high frame-rate and prediction of possible actions from a learned action graph that represents possible handling variants for a specific object. The system can be used to train a novice in an unknown environment providing expert knowledge. We present our implementation of the system in a service scenario of a kitchen environment, where the system supports the user while performing the actions.","Title: Robust Event Detection based on Spatio-Temporal Latent Action Unit using Skeletal Information\nYear: 2021\n\nAbstract: This paper proposes a novel dictionary learning approach to detect event anomalities using skeletal information extracted from RGBD video. The event action is represented as several latent action atoms and composed of latent spatial and temporal attributes. We aim to construct a network able to learn from few examples and also rules defined by the user. The skeleton frames are clustered by an initial K-means method. Each skeleton frame is assigned with a varying weight parameter and fed into our Gradual Online Dictionary Learning (GODL) algorithm. During the training process, outlier frames will be gradually filtered by reducing the weight that is inversely proportional to a cost. To strictly distinguish the event action from similar actions and robustly acquire its action units, we build a latent unit temporal structure for each sub-action. We validate the method at the example of fall event detection on NTU RGB+D dataset, because it provides a benchmark available for comparison. We present the experimental validation of the achieved accuracy, recall, and precision. Our approach achieves the best performance in precision and accuracy of human fall event detection, compared with other existing dictionary learning methods. Our method remains the highest accuracy and the lowest variance, with increasing noise ratio.","Title: Direct Image Based Traffic Junction Crossing System for Autonomous Vehicles\nYear: 2021\n\nAbstract: One of the most common traffic scenario when navigating in urban area is the traffic junction. Crossing a traffic junction is not trivial for an autonomous vehicle as it needs to perform both scene understanding and decision making tasks. In this work we introduce a two-stage vision-based system for an autonomous vehicle that is capable of deciding when to cross a traffic junction safely. The firs...","Title: Estimating Dense Optical Flow of Objects for Autonomous Vehicles\nYear: 2021\n\nAbstract: Autonomous vehicles need to be able to perceive both the presence and motion of objects in the surrounding environment to navigate in the real world. In this work, we propose to solve the tasks of identifying objects and estimating the corresponding motion by viewing them as a single unified task known as instance flow. Instance flow provides the pixel-wise instance mask of an object and the dense optical flow within it. To achieve this, we extended the state of the art object detection model to include a dense optical flow estimator. The estimator is used to estimate the optical flow for each region of interest only, instead of the entire image. We tested the approach by carrying out experiments on publicly available datasets for autonomous driving research, VKITTI, KITTI and HD1K. Furthermore, we also introduced a new instance flow quality metric to evaluate the instance flow estimation.","Title: A Dual Doctor-Patient Twin Paradigm for Transparent Remote Examination, Diagnosis, and Rehabilitation\nYear: 2021\n\nAbstract: The need for comprehensive telemedicine solutions is becoming increasingly relevant due to challenges associated with the ageing population, the increasing shortage of healthcare providers, and, more recently, the global pandemic. Existing solutions primarily focus on, e.g., electronic medical records, audiovisual connections, and, in some cases, robotic systems with very basic capabilities. Here we present a fundamentally new, holistic approach to a remote doctor visit, which enables transparent remote examination, anomaly detection, diagnosis, and rehabilitation. Our dual doctor-patient twin paradigm involves two robotic systems: one representing the doctor to the patient (\"GARMI\") and one representing the patient to the doctor (\"MUCKI\"). Through bidirectional telepresence control, this system enables transparent, natural, remote haptic interaction between doctor and patient. The control, interaction, and knowledge transfer to the doctor is enhanced by AI-based visual motion and facial expression analysis as well as a digital twin of the patient. Thus, each stage of a doctor visit can be replicated in the context of telemedicine and shared autonomy: from first assessment to observation-based and remote physical examination, to a better-informed doctor diagnosis and robot-assisted telerehabilitation.","Title: Joint prediction of monocular depth and structure using planar and parallax geometry\nYear: 2022\n\nAbstract: •Joint prediction of depth and structure.•A promising plane and parallax pipeline.•Enhance depth prediction on thin objects and edges.•Enhance structure prediction at epipole and without ego motion."],"string":"[\n \"Title: The 4D Touchpad: Unencumbered HCI With VICs.\\nYear: 2003\\n\\nAbstract: Abstract, We present a platform for human-machine in-terfaces that provides functionality for robust, unencumbered interaction: the 4D Touchpad (4DT). The goal is direct in-teraction with interface components through intuitive actions and gestures. The 4DT is based on the 3D-2D Projection-based mode of the VICs framework. The fundamental idea behind VICs is that expensive global image processing with user modeling and tracking is not necessary in general vision-based HCI. Instead, interface components operating under simple-to-complex rules in local image regions provide more robust and less costly functionality with 3 spatial dimensions and 1 temporal dimension. A prototype realization of the 4DT platform is presented; it operates through a set of planar\",\n \"Title: Stochastic global optimization for robust point set registration\\nYear: 2011\\n\\nAbstract: In this paper, we propose a new algorithm for pairwise rigid point set registration with unknown point correspondences. The main properties of our method are noise robustness, outlier resistance and global optimal alignment. The problem of registering two point clouds is converted to a minimization of a nonlinear cost function. We propose a new cost function based on an inverse distance kernel that significantly reduces the impact of noise and outliers. In order to achieve a global optimal registration without the need of any initial alignment, we develop a new stochastic approach for global minimization. It is an adaptive sampling method which uses a generalized BSP tree and allows for minimizing nonlinear scalar fields over complex shaped search spaces like, e.g., the space of rotations. We introduce a new technique for a hierarchical decomposition of the rotation space in disjoint equally sized parts called spherical boxes. Furthermore, a procedure for uniform point sampling from spherical boxes is presented. Tests on a variety of point sets show that the proposed registration method performs very well on noisy, outlier corrupted and incomplete data. For comparison, we report how two state-of-the-art registration algorithms perform on the same data sets.\",\n \"Title: Real time landscape modelling and visualization\\nYear: 2007\\n\\nAbstract: With the rapid development of information and communication technology and widely spreading of internet, digital landscape becomes a high topic recently. This paper presents a landscape modeling- and visualizationssystem. The first part of this paper focuses on the real time 3D-model- lingsprocess out of large point-clouds. Diverse experiments have been done on the reconstruction of various famous regions of Bavaria with tourist features. And the second part concentrates on the interactive online visualizationssystem for massive meshes. To enable an efficient interactive online visualization of these large meshes, we convert them firstly with a multi-resolution hierarchy, and then display them progressively. As a preprocessing for the inter-active rendering, we generate a hierarchical tree of bounding spheres from triangle meshes and write it to disk. It will be used for view frustum culling, backface culling and level-of-detail control. We use a recursive algorithm for display. And the traverse-depth in the tree is decided by the projected size of the current node on the screen. By an interactive rendering, once the user stops moving the mouse, the scene will be redrawn with successively smaller thresholds until a size of one pixel is reached.\",\n \"Title: Navigating inner space: 3-D assistance for minimally invasive surgery\\nYear: 2005\\n\\nAbstract: Since its inception about three decades ago, modern minimally invasive surgery has made huge advances in both technique and technology. However, the minimally invasive surgeon is still faced with daunting challenges in terms of visualization and hand-eye coordination.\",\n \"Title: Estimation of spatio-temporal object properties for manipulation tasks from observation of humans\\nYear: 2010\\n\\nAbstract: We propose a system for vision-based estimation of manipulation-relevant properties of objects in natural scenes based on observation of human actions. The system consists of an a-priori (Atlas) knowledge about known generic objects in the scene and classifies the scene into mission relevant objects and background geometry that is important only for collision avoidance. We present the object-centric structure of our system consisting of an Atlas representation and a Working Memory storing the current knowledge about the scene, the manipulated objects and actions applied to them in the local environment.We present experimental results how the system maintains the information in the database and we show the quality of the results that can be obtained with our system.\",\n \"Title: A novel approach to automatic registration of point clouds\\nYear: 2007\\n\\nAbstract: For the 3D reconstruction inside historic buildings, we need a marker-free automatic registration approach to align different views together, because GPS does not work indoors and markers are not allowed to paste on the walls. This paper presents an automatic matching process, which employs a novel algorithm, Dynamic Matching Tree technique, for a fast and stable coarse-matching to achieve the automatic pre-alignment of two point clouds and uses modified ICP to do a fine matching efficiently. The whole process can be divided in the following stages: preprocessing, 2-View matching and N-View matching. To validate our method, various experiments has been done on reconstruction of historic sites and industrial objects.\",\n \"Title: Automation of Manual Tasks for Minimally Invasive Surgery\\nYear: 2008\\n\\nAbstract: We have developed an experimental system for minimally invasive surgery providing force feedback and automation of recurring task. The system consists of four robotic arms, which can be equipped with either minimally invasive instruments or a stereo camera.The master console provides a stereo view of the field of operation and two input devices can feed back forces to the user. We have utilized this system to assess the possibility of automating difficult handling tasks like surgical knot tying. In order to achieve this, a novel approach for human-machine skill transfer was developed. It constitutes an extension to learning by demonstration, which is a well known paradigm of robotic learning.\",\n \"Title: Vision-Based 3d Scene Analysis For Driver Assistance\\nYear: 2005\\n\\nAbstract: We present a vision-based system for traffic sign detection and ego-motion estimation in road scenarios. The system is capable of autonomous scene reconstruction and classification. It is used to pre-select candidate surfaces in the vicinity of the road that should be inspected more closely by a sign recognition system.We compare two approaches based on a binocular and a monocular camera system, respectively. We discuss their advantages and disadvantages for applications in driver assistance systems.\",\n \"Title: Fusion of laserscannner and video based lanemarking detection for robust lateral vehicle control and lane change maneuvers.\\nYear: 2011\\n\\nAbstract: The knowledge about lanes and the exact position on the road is fundamental for many advanced driver assistance systems. In this paper, a novel iterative histogram based approach with occupancy grids for the detection of multiple lanes is proposed. In highway scenarios, our approach is highly suitable to determine the correct number of all existing lanes on the road. Additionally, the output of the laserscannner based lane detection is fused with a production-available vision based system. It is shown that both sensor systems perfectly complement each other to increase the robustness of a lane tracking system. The achieved accuracy of the fusion system, the laserscannner and video based system is evaluated with a highly accurate DGPS to investigate the performance with respect to lateral vehicle control applications.\",\n \"Title: A dynamic 3D environmental model with real-time access functions for use in autonomous mobile robots\\nYear: 1995\\n\\nAbstract: A model of the environment is a mandatory requirement for the autonomy of a mobile robot. In this paper, we present a framework for the prediction of expected sensor images on feature level, which is based on a-priori knowledge about the geometry of the environment. Our algorithm is capable to serve all distance and image measuring sensors typically found on mobile robots in real time. Fast prediction is achieved by using concepts from database technology and computer graphics. By incorporating differences between the expected and sensed image, the model can be adapted to changes and uncertainties in the environment. So the predicted features can be attributed with uncertainties to support and enhance the match process.\",\n \"Title: Real-time 3D Surface Tracking and Its Applications\\nYear: 2004\\n\\nAbstract: We present a general technique for directly estimating and tracking surfaces from a stream of rectified stereo pairs in real-time. These techniques are based on the iterative updating of surface representations directly from image information and use no disparity search except during initialization. We perform the tracking through an iteratively re-weighted least squares minimization wherein a mask is incorporated to increase robustness to occlusion. The algorithms are formulated for a general family of linear in parameters surface models and discussed for the cases of planar surfaces and tensor product surfaces. These algorithms have been implemented on standard hardware and run at or near frame rate, with accuracy on the order of 1/20 of a pixel. We discuss applications of the technique including mobile robot localization, general deforming surface tracking, and biometry of biological surfaces.\",\n \"Title: Fast recovery of weakly textured surfaces from monocular image sequences\\nYear: 2010\\n\\nAbstract: We present a method for vision-based recovery of threedimensional structures through simultaneous model reconstruction and camera position tracking from monocular images. Our approach does not rely on robust feature detecting schemes (such as SIFT, KLT etc.), but works directly on intensity values in the captured images. Thus, it is well-suited for reconstruction of surfaces that exhibit only minimal texture due to partial homogeneity of the surfaces. Our method is based on a well-known optimization technique, which has been implemented in an efficient yet flexible way, in order to achieve high performance while ensuring extensibility.\",\n \"Title: Direct pose estimation with a monocular camera\\nYear: 2008\\n\\nAbstract: We present a direct method to calculate a 6DoF pose change of a monocular camera for mobile navigation. The calculated pose is estimated up to a constant unknown scale parameter that is kept constant over the entire reconstruction process. This method allows a direct calculation of the metric position and rotation without any necessity to fuse the information in a probabilistic approach over longer frame sequence as it is the case in most currently used VSLAM approaches. The algorithm provides two novel aspects to the field of monocular navigation. It allows a direct pose estimation without any a-priori knowledge about the world directly from any two images and it provides a quality measure for the estimated motion parameters that allows to fuse the resulting information in Kalman Filters. We present the mathematical formulation of the approach together with experimental validation on real scene images.\",\n \"Title: VICs: a modular vision-based HCI framework\\nYear: 2003\\n\\nAbstract: Many Vision-Based Human-Computer Interaction (VBHCI) systems are based on the tracking of user actions. Examples include gaze-tracking, head-tracking, finger-tracking, and so forth. In this paper, we present a framework that employs no user-tracking; instead, all interface components continuously observe and react to changes within a local image neighborhood. More specifically, components expect a pre-defined sequence of visual events called Visual Interface Cues (VICs). VICs include color, texture, motion and geometric elements, arranged to maximize the veridicality of the resulting interface element. A component is executed when this stream of cues has been satisfied. We present a general architecture for an interface system operating under the VIC-Based HCI paradigm, and then focus specifically on an appearance-based system in which a Hidden Markov Model (HMM) is employed to learn the gesture dynamics. Our implementation of the system successfully recognizes a button-push with a 96% success rate. The system operates at frame-rate on standard PCs.\",\n \"Title: Modeling kinematics of mobile C-arm and operating table as an integrated six degrees of freedom imaging system\\nYear: 2010\\n\\nAbstract: Maneuvering mobile C-arms to a desired position and orientation during surgery is not only a routine surgical task, e.g. for C-arm repositioning, but also an indispensable step for advanced X-ray imaging techniques, e.g. parallax-free X-ray image stitching. Standard mobile C-arms have only five degrees of freedom (DOF), which definitely restricts their motions that have six DOF in 3D Cartesian space. In this paper, we enable the mobile C-arm to have six DOF relative to the patient's table by integrating a translational movement of the patient's table into the mobile C-arm kinematics. We present a novel method to model the kinematics of the mobile C-arm and operating table as an integrated 6DOF C-arm X-ray imaging system. Kinematic singularities of the 6DOF C-arm model are determined by analyzing its manipulator Jacobian matrix. Inverse kinematic analysis is employed in order to find the required joint values to move the C-arm into the desired position and orientation. Our proposed 6DOF C-arm modeling paves the way for advanced applications in the fields of surgical navigation and advanced X-ray imaging that require C-arms to be precisely positioned or repositioned relative to the patient's table with six DOF. In our implementation, we employ a visual planar marker pattern and a standard mobile C-arm augmented by a video camera in order to obtain a relationship between the C-arm system and the patient's table. C-arm repositioning experiments on phantom study demonstrate the practicality and accuracy of our developed 6DOF C-arm system, and show the improved accuracy of C-arm repositioning by using the 6DOF C-arm model over the 5DOF C-arm model.\",\n \"Title: Real-time Image-based Localization for Hand-held 3D-modeling\\nYear: 2010\\n\\nAbstract: We present a self-referencing hand-held scanning device for vision-based close-range 3D-modeling. Our approach replaces external\\n global tracking devices with ego-motion estimation directly from the camera used for reconstruction. The system is capable\\n of online estimation of the 6DoF pose on hand-held devices with high motion dynamics especially in rotational components.\\n Inertial information supports directly the tracking process to allow for robust tracking and feature management in highly\\n dynamic environments. We introduce a weighting function for landmarks that contribute to the pose estimation increasing the\\n accuracy of the localization and filtering outliers in the tracking process. We validate our approach with experimental results\\n showing the robustness and accuracy of the algorithm. We compare the results to external global referencing solutions used\\n in current modeling systems.\",\n \"Title: An efficient RANSAC for 3D object recognition in noisy and occluded scenes\\nYear: 2010\\n\\nAbstract: In this paper, we present an efficient algorithm for 3D object recognition in presence of clutter and occlusions in noisy, sparse and unsegmented range data. The method uses a robust geometric descriptor, a hashing technique and an efficient RANSAC-like sampling strategy. We assume that each object is represented by a model consisting of a set of points with corresponding surface normals. Our method recognizes multiple model instances and estimates their position and orientation in the scene. The algorithm scales well with the number of models and its main procedure runs in linear time in the number of scene points. Moreover, the approach is conceptually simple and easy to implement. Tests on a variety of real data sets show that the proposed method performs well on noisy and cluttered scenes in which only small parts of the objects are visible.\",\n \"Title: Toward a Fully Autonomous UAV: Research Platform for Indoor and Outdoor Urban Search and Rescue.\\nYear: 2012\\n\\nAbstract: Urban search and rescue missions raise special requirements on robotic systems. Small aerial systems provide essential support to human task forces in situation assessment and surveillance. As external infrastructure for navigation and communication is usually not available, robotic systems must be able to operate autonomously. A limited payload of small aerial systems poses a great challenge to the system design. The optimal tradeoff between flight performance, sensors, and computing resources has to be found. Communication to external computers cannot be guaranteed; therefore, all processing and decision making has to be done on board. In this article, we present an unmanned aircraft system design fulfilling these requirements. The components of our system are structured into groups to encapsulate their functionality and interfaces. We use both laser and stereo vision odometry to enable seamless indoor and outdoor navigation. The odometry is fused with an inertial measurement unit in an extended Kalman filter. Navigation is supported by a module that recognizes known objects in the environment. A distributed computation approach is adopted to address the computational requirements of the used algorithms. The capabilities of the system are validated in flight experiments, using a quadrotor.\",\n \"Title: DaVinci canvas: a telerobotic surgical system with integrated, robot-assisted, laparoscopic ultrasound capability.\\nYear: 2005\\n\\nAbstract: We present daVinci Canvas: a telerobotic surgical system with integrated robot-assisted laparoscopic ultrasound capability. DaVinci Canvas consists of the integration of a rigid laparoscopic ultrasound probe with the daVinci robot, video tracking of ultrasound probe motions, endoscope and ultrasound calibration and registration, autonomous robot motions, and the display of registered 2D and 3D ultrasound images. Although we used laparoscopic liver cancer surgery as a focusing application, our broader aim was the development of a versatile system that would be useful for many procedures.\",\n \"Title: Dynamic composition of tracking primitives for interactive vision-guided navigation\\nYear: 2001\\n\\nAbstract: We present a system architecture for robust target following with a mobile robot. The system is based on tracking multiple cues in binocular stereo images using the XVision toolkit [1]. Fusion of complementary information in the images, including texture, color and depth, combined with a fast optimized processing reduces the possibility of loosing the tracked object in a dynamic scene with several moving targets on intersecting paths. The presented system is capable of detecting objects obstructing its way as well as gaps. It supports application in more cluttered terrain. where a wheel drive of mobile robot cannot take the same path as a walking person. We describe the basic principles of the fast feature extraction and tracking in the luminance, chrominance and disparity domain. The optimized tracking algorithms compensate for illumination variations and perspective distortions as already presented in our previous publications about the XVision system.\",\n \"Title: Epipolar-Based Stereo Tracking Without Explicit 3D Reconstruction\\nYear: 2010\\n\\nAbstract: We present a general framework for tracking image regions in two views simultaneously based on sum-of-squared differences (SSD) minimization. Our method allows for motion models up to affine transformations. Contrary to earlier approaches, we incorporate the well-known epipolar constraints directly into the SSD optimization process. Since the epipolar geometry can be computed from the image directly, no prior calibration is necessary. Our algorithm has been tested in different applications including camera localization, wide-baseline stereo, object tracking and medical imaging. We show experimental results on robustness and accuracy compared to the known ground truth given by a conventional tracking device.\",\n \"Title: Deformable 3D Shape Registration Based on Local Similarity Transforms.\\nYear: 2011\\n\\nAbstract: In this paper, a new method for deformable 3D shape registration is proposed. The algorithm computes shape transitions based on local similarity transforms which allows to model not only as-rigid-as-possible deformations but also local and global scale. We formulate an ordinary differential equation (ODE) which describes the transition of a source shape towards a target shape. We assume that both shapes are roughly pre-aligned (e. g., frames of a motion sequence). The ODE consists of two terms. The first one causes the deformation by pulling the source shape points towards corresponding points on the target shape. Initial correspondences are estimated by closest-point search and then refined by an efficient smoothing scheme. The second term regularizes the deformation by drawing the points towards locally defined rest positions. These are given by the optimal similarity transform which matches the initial (undeformed) neighborhood of a source point to its current (deformed) neighborhood. The proposed ODE allows for a very efficient explicit numerical integration. This avoids the repeated solution of large linear systems usually done when solving the registration problem within general-purpose non-linear optimization frameworks. We experimentally validate the proposed method on a variety of real data and perform a comparison with several state-of-the-art approaches.\",\n \"Title: Identification of 3D Reference Structures for Video-Based Localization\\nYear: 1998\\n\\nAbstract: The bootstrap--problem of self--localization in indoor environments is a demandingtask for initial localization and topological navigation. The ability to determinethe position in an a priori known or already explored environment allows unsuperviseduse of mobile robots in environments such as private households. Thispaper presents our approach to identify a given set of known reference structuresin a three--dimensional map of the local environment. This map is constructedfrom the data...\",\n \"Title: Robust Feature Correspondences For Vision-Based Navigation With Slow Frame-Rate Cameras\\nYear: 2006\\n\\nAbstract: We propose a vision-based inertial system that overcomes the problems associated with slow update rates in navigation systems based on high-resolution cameras. Due to bandwidth limitations in current camera interfaces, like Firewire or USB, an increase in the camera resolution results in a drop of the effective frame-rate from the sensor. This increases the correspondence problem for point features in consecutive images due to significant motion of the features. We solve the correspondence problem for very significant motion of point features between consecutive images by analyzing the motion blur to estimate the current motion parameters.The proposed algorithm can be used to track the position of point features in video images originating from slow frame-rate cameras. The system is validated on real images from a camera moved by a mobile system, but it can be used for any type of motion ranging from flying systems to mobile robots operating in outdoor or indoor environments.\",\n \"Title: Scale-invariant registration of monocular endoscopic images to CT-scans for sinus surgery.\\nYear: 2005\\n\\nAbstract: In this paper, we present a novel method for intra-operative registration directly from monocular endoscopic images. This technique has the potential to provide a more accurate surface registration at the surgical site than existing methods. It can operate autonomously from as few as two images and can be particularly useful in revision cases where surgical landmarks may be absent. A by-product of video registration is an estimate of the local surface structure of the anatomy, thus providing the opportunity to dynamically update anatomical models as the surgery progresses.\",\n \"Title: Recent Methods for Image-Based Modeling and Rendering\\nYear: 2003\\n\\nAbstract: A long-standing goal in image-based modeling and rendering is to capture a scene fromcamera images and construct a sufficient model to allow photo-realistic rendering of new views.With the confluence of computer graphics and vision, the combination of research on recoveringgeometric structure from uncalibrated cameras with modeling and rendering has yieldednumerous new methods. Yet, many challenging issues remain to be addressed before asufficiently general and robust system could be built to (for instance) allow an average user tomodel their home and garden from camcorder video. This tutorial aims to give researchers andstudents in computer graphics a working knowledge of relevant theory and techniques coveringthe steps from real-time vision for tracking and the capture of scene geometry and appearance, tothe efficient representation and real-time rendering of image-based models. It also includeshands-on demos of real-time visual tracking, modeling and rendering systems.\",\n \"Title: VICs: A modular HCI framework using spatiotemporal dynamics\\nYear: 2004\\n\\nAbstract: Many vision-based human-computer interaction systems are based on the tracking of user actions. Examples include gaze tracking, head tracking, finger tracking, etc. In this paper, we present a framework that employs no user tracking; instead, all interface components continuously observe and react to changes within a local neighborhood. More specifically, components expect a predefined sequence of visual events called visual interface cues (VICs). VICs include color, texture, motion, and geometric elements, arranged to maximize the veridicality of the resulting interface element. A component is executed when this stream of cues has been satisfied. We present a general architecture for an interface system operating under the VIC-based HCI paradigm and then focus specifically on an appearance-based system in which a hidden Markov model (HMM) is employed to learn the gesture dynamics. Our implementation of the system successfully recognizes a button push with a 96% success rate.\",\n \"Title: Dynamic Augmented Reality For Sensory Substitution In Robot-Assisted Surgical Systems\\nYear: 2006\\n\\nAbstract: Teleoperated robot-assisted surgical systems provide surgeons with improved precision, dexterity, and visualization over traditional minimally invasive surgery. The addition of haptic (force and/or tactile) feedback has been proposed as a way to further enhance the performance of these systems. However, due to limitations in sensing and control technologies, implementing direct haptic feedback to the surgeon's hands remains impractical for clinical application. A new, intuitive augmented reality system for presentation of force information through sensory substitution has been developed and evaluated. The augmented reality system consists or force-sensing robotic instruments, a kinematic tool tracker, and a graphic display that overlays a visual representation of force levels on top of the moving instrument lips. The system is integrated with the da Vinci Surgical System (Intuitive Surgical, Inc.) and tested by several users in a phantom knot tying task. The augmented reality system decreases the number of broken sutures, decreases the number of loose knots, and results in more consistent application of forces.\",\n \"Title: Adaptive and generic corner detection based on the accelerated segment test\\nYear: 2010\\n\\nAbstract: The efficient detection of interesting features is a crucial step for various tasks in Computer Vision. Corners are favored cues due to their two dimensional constraint and fast algorithms to detect them. Recently, a novel corner detection approach, FAST, has been presentedwhich outperforms previous algorithms in both computational performance and repeatability. We will show how the accelerated segment test, which underlies FAST, can be significantly improved by making it more generic while increasing its performance.We do so by finding the optimal decision tree in an extended configuration space, and demonstrating how specialized trees can be combined to yield an adaptive and generic accelerated segment test. The resulting method provides high performance for arbitrary environments and so unlike FAST does not have to be adapted to a specific scene structure. We will also discuss how different test patterns affect the corner response of the accelerated segment test.\",\n \"Title: Illumination-invariant image-based novelty detection in a cognitive mobile robot's environment\\nYear: 2010\\n\\nAbstract: Image-based scene representations enable a mobile robot to make a realistic prediction of its environment. Hence, it is able to rapidly detect changes in its surroundings by comparing a virtual image generated from previously acquired reference images and its current observation. This facilitates attentional control to novel events. However, illumination effects can impair attentional control if the robot does not take them into account. To address this issue, we present in this paper an approach for the acquisition of illumination-invariant scene representations. Using multiple spatial image sequences which are captured under varying illumination conditions the robot computes an illumination-invariant image-based environment model. With this representation and statistical models about the illumination behavior, the robot is able to robustly detect texture changes in its environment under different lighting. Experimental results show high-quality images which are free of illumination effects as well as more robust novelty detection compared to state-of-the-art methods.\",\n \"Title: Vision Based Control of Mobile Robots\\nYear: 2001\\n\\nAbstract: Abstract: This paper presents an approach for direct controlof a mobile robot to keep it on a pre-taught path basedsolely on the perception from a monocular CCD camera.In particular, we present a novel vision-basedcontrol algorithm for mobile systems equipped with aconventional camera and a pan-tilt head or with anomnidirection camera. This algorithm avoids numericalinstabilities of previously reported approaches. Theexperimental performance of the method as well as itspractical limitations are...\",\n \"Title: Rgb-D Sensor Data Correction And Enhancement By Introduction Of An Additional Rgb View\\nYear: 2013\\n\\nAbstract: RGB-D sensors are becoming more and more vital to robotics. Sensors such as the Microsoft Kinect and time of flight cameras provide 3D colored point-clouds in real time can play a crucial role in Robot Vision. However these sensors suffer from precision deficiencies, and often the density of the point-clouds they provide is insufficient. In this paper, we present a multi-camera system for correction and enhancement of the data acquired from an RGB-D sensor. Our system consists of two sensors, the RGB-D sensor (main sensor) and a regular RGB camera (auxiliary sensor). We perform the correction and the enhancement of the data acquired from the RGB-D sensor by placing the auxiliary sensor in a close proximity to the target object and taking advantage of the established epipolar geometry. We have managed to reduce the relative error of the raw point-cloud from a Microsoft Kinect RGB-D sensor by 74.5% and increase its density up to 2.5 times.\",\n \"Title: Stochastic Optimization for Rigid Point Set Registration\\nYear: 2009\\n\\nAbstract: In this paper we propose a new method for pairwise rigid point set registration. We pay special attention to noise robustness, outlier resistance and global optimal alignment. The problem of registering two point clouds in space is converted to a minimization of a nonlinear cost function. We propose a cost function that aims to reduce the impact of noise and outliers. Its definition is based on the input point sets and is directly related to the quality of a concrete rigid transform between them. In order to achieve a global optimal registration, without the need of a good initial alignment, we develop a new stochastic approach for global minimization. Tests on a variety of point sets show that the proposed registration algorithm performs very well on noisy, outlier corrupted and incomplete data.\",\n \"Title: Rigid 3D geometry matching for grasping of known objects in cluttered scenes\\nYear: 2012\\n\\nAbstract: In this paper, we present an efficient 3D object recognition and pose estimation approach for grasping procedures in cluttered and occluded environments. In contrast to common appearance-based approaches, we rely solely on 3D geometry information. Our method is based on a robust geometric descriptor, a hashing technique and an efficient, localized RANSAC-like sampling strategy. We assume that each object is represented by a model consisting of a set of points with corresponding surface normals. Our method simultaneously recognizes multiple model instances and estimates their pose in the scene. A variety of tests shows that the proposed method performs well on noisy, cluttered and unsegmented range scans in which only small parts of the objects are visible. The main procedure of the algorithm has a linear time complexity resulting in a high recognition speed which allows a direct integration of the method into a continuous manipulation task. The experimental validation with a seven-degree-of-freedom Cartesian impedance controlled robot shows how the method can be used for grasping objects from a complex random stack. This application demonstrates how the integration of computer vision and soft-robotics leads to a robotic system capable of acting in unstructured and occluded environments.\",\n \"Title: A biologically inspired navigation concept based on the Landmark-Tree map for efficient long-distance robot navigation.\\nYear: 2014\\n\\nAbstract: Map-based navigation is a crucial task for any mobile robot. Usually, in an unknown environment, this problem is addressed by applying Simultaneous Localization and Mapping based on metric grid-maps. However, such maps are in general rather computational expensive and do not scale well. Insects are able to cover large distances and reliably find back to their nests, although they are quite limited in their resources. Inspired by theories on insect navigation, we developed a data structure which is highly scalable and efficiently adapts to the available memory during run-time. Positions in space are memorized as snapshots, which are unique configurations of landmarks. Unlike conventional snapshot or visual map approaches, we do not simply store the landmarks as a set, but we arrange them in a tree-like structure according to the relevance of their information. The resulting navigation solely relies on the direction measurements of arbitrary landmarks. In this work, we present the concept of the Landmark-Tree (LT) map and apply it to a mobile platform equipped with an omnidirectional camera. We verify the reliability and robustness of the LT-map concept in simulations as well as by experiments with the robotic platform.\",\n \"Title: A Practical Paradigm and Platform for Video-Based Human-Computer Interaction\\nYear: 2008\\n\\nAbstract: New technologies that use multimodal input, human experience, and modern hardware's full computational power could mitigate current limitations in human-computer interaction. The 4D Touchpad, a video-based interaction platform, makes robust, natural interaction between humans and computers possible.\",\n \"Title: 3D reconstruction of dynamic scenes from two asynchronous video-streams\\nYear: 2014\\n\\nAbstract: We present an algorithm for reconstruction of dynamic scenes from a video input of an asynchronous stereo-pair. Our method presumes that the timestamps of the frame acquisitions and the intrinsic parameters of the stereo cameras are known, as well as, that the extrinsic parameters can be estimated from static regions of the scene. It computes the 3D trajectory of each individual point by modeling its motion parameters. Our algorithm requires in addition to the two asynchronous images from the camera pair, two additional images from one of the cameras for its processing. Since dynamic scene elements cause wrong reconstructions, here we introduce a two stage process in which the directions of the possible motion components are estimated prior to the 3D pose estimation of the corresponding point.\",\n \"Title: Dense and Deformable Motion Extraction in Dynamic Scenes Based on Hierarchical MRF Optimization in RGB-D Images\\nYear: 2015\\n\\nAbstract: We present a novel hierarchical MRFs optimization method for dense and deformable motion extraction in dynamic scenes. In particular, this hierarchical MRFs structure consists of two layers, the segmentation and the correspondence layer. Firstly, dynamic RGB-D foreground data is segmented through a pixel-level MRF in the segmentation layer. Subsequently, the extracted foreground data is transformed into a 3D point-level MRF in the correspondence layer. A new surface descriptor named deformable color and shape histogram is proposed. It is combined with photometric and geometric features to represent a deformable surface. Finally, the dynamic scene motion is retrieved from correspondences established in the image sequence. Discrete optimization schemes are used for the binary classification and multi-labeling problems. We provide an RGB-D dataset of dynamic scenes, which involves different motion patterns and surface properties of foreground objects. The effectiveness and efficiency of our proposed approach for high accurate foreground segmentation and motion extraction is validated in experiments.\",\n \"Title: Local reference filter for life-long vision aided inertial navigation\\nYear: 2014\\n\\nAbstract: Filter based system state estimation is widely used for hard-realtime applications. In long-term filter operation the estimation of unobservable system states can lead to numerical instability due to unbounded state uncertainties. We introduce a filter concept that estimates system states in respect to changing local references instead of one global reference. In this way unbounded state covariances can be reset in a consistent way. We show how local reference (LR) filtering can be integrated into filter prediction to be used in square root filter implementations. The concept of LR-filtering is applied to the problem of vision aided inertial navigation (LR-INS). The results of a simulated 24 h quadrotor flight using the LR-INS demonstrate longterm filter stability. Real quadrotor flight experiments show the usability of the LR-INS for a highly dynamic system with limited computational resources.\",\n \"Title: A framework for dynamic sensory substitution\\nYear: 2014\\n\\nAbstract: In this paper we present a framework for dynamic substitution of different sensory modalities with existing physical sensors. Our system is capable of finding the most optimal set of mathematical and physical transformations between two modalities of physical and virtual sensors. It allows a creation of new virtual sensors from given set of physical sensors. The virtual sensing may extend to new sensing modalities for which no direct physical sensors exist. The framework optimizes for a minimal error and optimal observation in the resulting fusion. It is processing the chain for a given spatial measurement and measurement range. The framework is capable of increasing the reliability of acquired data in multi-sensor systems by being able to asses the amount of accumulated errors. We give two examples of real-world applications of this framework in robotic environments.\",\n \"Title: Stereo-based obstacle avoidance in indoor environments with active sensor re-calibration\\nYear: 2002\\n\\nAbstract: We present a stereo-based obstacle avoidance sys- tem for mobile vehicles. The system operates in three steps. First, it models the surface geometry of support- ing surface and removes the supporting surface from the scene. Next, it segments the remaining stereo dis- parities into connected components in image and dis- parity space. Finally, it projects the resulting con- nected components onto the supporting surface and plans a path around them. One interesting aspect of this system is that it can detect both positive and \\\\neg- ative\\\" obstacles (e.g. stairways) in its path. The algorithms we have developed have been imple- mented on a mobile robot equipped with a real-time stereo system. We present experimental results on indoor environments with planar supporting surfaces that show the algorithms to be both fast and robust.\",\n \"Title: Scene classification from dense disparity maps in indoor environments\\nYear: 2002\\n\\nAbstract: We present our approach for scene classification in dense disparity maps from a binocular stereo system. The classification result is used for tracking and navigation purposes. The presented system is capable of foreground-background separation classifying room structures. The 3D model of the scene is derived directly from the disparity image. This approach is used for initial target selection and scene classification in mobile navigation. It is used on our mobile system for target tracking, but can also be used for localization as described in this paper. We describe the basic principles of our object detection and classification using disparity information from a binocular stereo system. The theoretical derivation is supported by results from the binocular stereo sensor system on our mobile robot.\",\n \"Title: Advances in computational stereo\\nYear: 2003\\n\\nAbstract: Extraction of three-dimensional structure of a scene from stereo images is a problem that has been studied by the computer vision community for decades. Early work focused on the fundamentals of image correspondence and stereo geometry. Stereo research has matured significantly throughout the years and many advances in computational stereo continue to be made, allowing stereo to be applied to new and more demanding problems. In this paper, we review recent advances in computational stereo, focusing primarily on three important topics: correspondence methods, methods for occlusion, and real-time implementations. Throughout, we present tables that summarize and draw distinctions among key ideas and approaches. Where available, we provide comparative analyses and we make suggestions for analyses yet to be done.\",\n \"Title: Optimal landmark configuration for vision-based control of mobile robots\\nYear: 2003\\n\\nAbstract: Abstract, We analyze the problem of finding the optimal placement of tracked primitives for robust vision-based con-trol of a mobile robot. The analysis evaluates the properties of the Image Jacobian matrix, used for direct generation of the control signals from the error signal in the image, and the accuracy of the underlying sensor system. The analysis is then used to select optimal tracking primitives that ensure good observability and controllability of the mobile system for a variety of sensor system configurations. The theoretical results are validated with our mobile robot for system configurations that use standard video cameras mounted on a pan-tilt head and catadioptric systems.\",\n \"Title: Direct plane tracking in stereo images for mobile navigation\\nYear: 2003\\n\\nAbstract: We present a novel plane tracking algorithm based on the direct update of surface parameters from two stereo images. The plane tracking algorithm is posed as an optimization problem, and maintains an iteratively re-weighted least squares approximation of the plane's orientation using direct pixel measurements. To facilitate autonomous operation, we include an algorithm for robust detection of significant planes in the environment. The algorithms have been implemented in a robot navigation system.\",\n \"Title: V-GPS - image-based control for 3D guidance systems\\nYear: 2003\\n\\nAbstract: We present our approach for pose verification with monocular cameras in 3-dimensional space based on the image-based control paradigm. We describe the extensions to our previous control system for mobile navigation that allow us to estimate the complete set of pose parameters in space. The major contribution of this approach is a sensor- independent formulation of the image formation that allows a flexible configuration with a variety of sensor systems including standard cameras, omnidirectional cameras and laser systems. Our second contribution is a way to re- initialize the tracked landmarks during a multi-segment navigation in applications with significant deviations from the pre-taught trajectory as it is the case for handheld systems and flying robots. The presented system can be used as a guidance system for visitors. The localization is based on known landmarks that are in our case natural landmarks in the environment. These landmarks correspond to the satellites of a GPS system. We call it V-GPS (vision-based GPS) because of this similarity in the concept. A camera carried by a person allows to navigate along pre-specified paths through environments, like galleries, hospitals, parks, and other public places.\",\n \"Title: Scale-invariant registration of monocular stereo images to 3D surface models\\nYear: 2004\\n\\nAbstract: We present an approach for scale recovery from monocular stereo images of an endoscopic camera with simul- taneous registration to dense 3D surface models. We assume the camera motion to be unknown or at least uncertain. An example application is the registration of endoscope images to pre-operative CT scans that allows instrument navigation during surgical procedures. The application field is not restricted to the medical field. It can be extended to registration of monocular video images to laser-based surface reconstructions in, e.g., mobile navigation area or to autonomous aircraft navigation from topological surveys. A novel way for depth estimation from arbitrary camera motion is presented. In this paper, we focus on the robust initialization of the system and on the scale recovery for the reconstructed 3D point clouds with accurate registration to the candidate surfaces extracted from the CT data. We provide experimen- tal validation of the algorithm with data obtained from our experiments with a phantom skull. I. MOTIVATION In endonasal surgery and other medical minimally inva- sive procedures, an endoscopic camera is used to provide information about the current instrument location to the surgeon. Since some sinus surgical procedures are close to optic nerves, the eyes, and the brain, surgeons require the best possible information during the surgery to guide the surgical instruments inside of the nasal cavities (Fig. 1). Fig. 1. Endoscopic inspection of the nasal Sinus cavities depicting the limited information provided to the surgeon. The necessary information is supplied primarily through the endoscope requiring from the surgeon a good knowl- edge of anatomy. Computer Integrated Surgery techniques has been em- ployed in the endonasal approach. Image-guided surgery system (IGS), that integrates pre-operative medical images with the endoscope information, supplies valuable infor- mation beyond what the endoscope alone can provide. In IGS, data from a preoperative CT scan is downloaded into the computer in the operating room and localizers are attached to surgical instruments. Once the patient's head position is registered, the software provides the surgeon with the 3D location of the tip of the instrument visualized relative to the pre-operative CT-scan. The current frame- less registration method for IGS is based on anatomic fiducial points or based on contour mapping (6). The accuracy of registration is crucial for any image-guided system. If registration errors occur, the localization ac- curacy suffers. Therefore, the operating surgeon must re- align the registration at several points in the operative field throughout the procedure.\",\n \"Title: Perception-based motion planning for indoor exploration\\nYear: 1999\\n\\nAbstract: This paper proposes an approach for motion planning in indoor environments based on incomplete and uncertain information from a line-based binocular stereo system. The primary goal of the planning process is to plan an optimal path through an unknown or partially known environment, depending on the information gained from exploration and the current mission goal. This paper presents an adaptable motion planner that supports sensor-based map construction, object recognition and navigation in an unknown environment while carrying out a mission. Also presented are some preliminary experimental results that demonstrate the utility of the approach\",\n \"Title: Visual homing and surprise detection for cognitive mobile robots using image-based environment representations\\nYear: 2009\\n\\nAbstract: One important feature of a cognitive system is to perceive and understand its environment and to adapt its actions to changes and unforeseen situations. In this paper, we propose a scheme for visual surprise detection in cognitive mobile robots. With the robot's observation and a set of reference images previously acquired near its current viewpoint, a pixel-wise surprise trigger is computed using Bayesian probabilistic inference techniques. With appropriate mathematical approximations this algorithm can be implemented on modern graphics hardware which nearly allows for real-time surprise detection. In order to refer to prior observations, a mobile robot has to be able to re-localize itself with respect to its environment. Thus, we also present two online image-based homing algorithms which both facilitate the computation of location-independent surprise triggers. Experiments show acceptable results in terms of robust and fast detection of unexpected changes in the environment.\",\n \"Title: State estimation for highly dynamic flying systems using key frame odometry with varying time delays\\nYear: 2012\\n\\nAbstract: System state estimation is an essential part for robot navigation and control. A combination of Inertial Navigation Systems (INS) and further exteroceptive sensors such as cameras or laser scanners is widely used. On small robotic systems with limitations in payload, power consumption and computational resources the processing of exteroceptive sensor data often introduces time delays which have to be considered in the sensor data fusion process. These time delays are especially critical in the estimation of system velocity. In this paper we present a state estimation framework fusing an INS with time delayed, relative exteroceptive sensor measurements. We evaluate its performance for a highly dynamic flight system trajectory including a flip. The evolution of velocity and position errors for varying measurement frequencies from 15Hz to 1Hz and time delays up to 1s is shown in Monte Carlo simulations. The filter algorithm with key frame based odometry permits an optimal, local drift free navigation while still being computationally tractable on small onboard computers. Finally, we present the results of the algorithm applied to a real quadrotor by flying from inside a house out through the window.\",\n \"Title: Efficient occupancy grid computation on the GPU with lidar and radar for road boundary detection\\nYear: 2010\\n\\nAbstract: Accurate maps of the static environment are essential for many advanced driver-assistance systems. In this paper a new method for the fast computation of occupancy grid maps with laser range-finders and radar sensors is proposed. The approach utilizes the Graphics Processing Unit to overcome the limitations of classical occupancy grid computation in automotive environments. It is possible to generate highly accurate grid maps in just a few milliseconds without the loss of sensor precision. Moreover, in the case of a lower resolution radar sensor it is shown that it is suitable to apply super-resolution algorithms to achieve the accuracy of a higher resolution laser-scanner. Finally, a novel histogram based approach for road boundary detection with lidar and radar sensors is presented.\",\n \"Title: Path optimization for abstractly represented tasks with respect to efficient control\\nYear: 2013\\n\\nAbstract: In order to be able to replace a human operator, a robotic manipulation system needs to deal with a variety of possible actions. These actions may be more or less constrained in their motion profile and in the accuracy of the transport goals. The robotic system can make use of some of this variation to simplify the control to improve the efficiency of the generated motion. Nevertheless, the human's intention behind the manipulation may not change. We introduce the Elastic Power Path to optimize paths with respect to efficient control in the context of abstractly represented tasks. Our experiments show, that the proposed Elastic Power Path is an efficient method to achieve this aim. The magnitude and the number of turnarounds of the accelerations along the path are significantly reduced.\",\n \"Title: Analysis of manipulator structures under joint-failure with respect to efficient control in task-specific contexts\\nYear: 2013\\n\\nAbstract: Robots are meanwhile able to perform several tasks. But what happens, if one or multiple of the robot's joints fail? Is the robot still able to perform the required tasks? Which capabilities of the robot get limited and which ones are lost? We propose an analysis of manipulator structures for the comparison of a robot's capabilities with respect to efficient control. The comparison is processed (1) within a robot in the case of joint failures and (2) between robots with or without joint failures. It is important, that the analysis can be processed independently of the structure of the manipulator. The results have to be comparable between different manipulator structures. Therefore, an abstract representation of the robot's dynamic capabilities is necessary. We introduce the Maneuverability Volume and the Spinning Pencil for this purpose. The Maneuverability Volume shows, how efficiently the end-effector can be moved to any other position. The Spinning Pencil reflects the robot's capability to change its end-effector orientation efficiently. Our experiments show not only the different capabilities of two manipulator structures, but also the change of the capabilities if one or multiple joints fail.\",\n \"Title: Monocular ego-motion estimation with a compact omnidirectional camera\\nYear: 2010\\n\\nAbstract: We present a generalization of the Koenderink-van Doorn (KvD) algorithm that allows robust monocular localization with large motion between the camera frames for a wide range of optical systems including omnidirectional systems and standard perspective cameras. The KvD algorithm estimates simultaneously ego-motion parameters, i.e. rotation, translation, and object distances in an iterative way. However due to the linearization of the rotational component of optic flow, the original algorithm fails for larger rotations. We present a generalization of the algorithm to arbitrary rotations that is especially suited for omnidirectional cameras where features can be tracked for long sequences. This reduces the need for vector summation of several individual motion estimates that leads to accumulation of odometry errors. The significant improvement in the performance of the proposed generalized algorithm compared to the original KvD implementation is validated using simulated data. The algorithm is also tested in a real-world experiment with ground-truth data obtained from an external tracking system. The experiment was carried out using a novel compact omnidirectional camera that is designed for small aerial vehicles. It consists of an off-the-shelf webcam that is combined with a reflective surface machined into acrylic glass.\",\n \"Title: Sparse keypoint models for 6D object pose estimation\\nYear: 2013\\n\\nAbstract: In this paper, we present an approach to generate sparse object models for keypoint-based 6D object pose estimation. Keypoint-based object models usually consist of thousands of keypoints. Our approach generates sparse models by identifying and removing keypoints that are not relevant to the object localization. It applies data association to detect duplicate keypoints and applies statistical analysis to identify keypoints that have not been detected reliably during model generation. Our approach furthermore ensures that keypoints are well distributed across the volume of the object model. We evaluated our approach using a SIFT-based 6D object localization system on the basis of real world datasets. In our experiments, we achieved a reduction of the model sizes to approximately 1% of the original model size without a substantial loss of localization performance.\",\n \"Title: Spatio-temporal prediction of collision candidates for static and dynamic objects in monocular image sequences\\nYear: 2013\\n\\nAbstract: This paper presents a novel approach for reactive obstacle avoidance for static and dynamic objects using monocular image sequences. A sparse motion field is calculated by tracking point features using the Kanade-Lucas-Tomasi method. The rotational component of this sparse optical flow due to ego motion of the camera is compensated using motion parameters estimated directly from the images. A robust method for detection of static and dynamic objects in the scene is applied to identify collision candidates. The approach operates entirely in the image space of a monocular camera and does not require any extrinsic information about the configuration of the sensor or speed of the camera. The system prioritizes the detected collision candidates by their time to collision. Additionally, the spatial distribution of the candidates is calculated for non-degenerated conditions. We present the mathematical framework and the experimental validation of the suggested approach on simulated and real-world data.\",\n \"Title: Motion Estimated-Compensated Reconstruction With Preserved-Features In Free-Breathing Cardiac Mri\\nYear: 2016\\n\\nAbstract: To develop an efficient motion-compensated reconstruction technique for free-breathing cardiac magnetic resonance imaging (MRI) that allows high-quality images to be reconstructed from multiple undersampled single-shot acquisitions. The proposed method is a joint image reconstruction and motion correction method consisting of several steps, including a non-rigid motion extraction and a motion-compensated reconstruction. The reconstruction includes a denoising with the Beltrami regularization, which offers an ideal compromise between feature preservation and staircasing reduction. Results were assessed in simulation, phantom and volunteer experiments. The proposed joint image reconstruction and motion correction method exhibits visible quality improvement over previous methods while reconstructing sharper edges. Moreover, when the acceleration factor increases, standard methods show blurry results while the proposed method preserves image quality. The method was applied to free-breathing single-shot cardiac MRI, successfully achieving high image quality and higher spatial resolution than conventional segmented methods, with the potential to offer high-quality delayed enhancement scans in challenging patients.\",\n \"Title: Effectiveness of Grasp Attributes and Motion-Constraints for Fine-Grained Recognition of Object Manipulation Actions.\\nYear: 2016\\n\\nAbstract: In this work, we consider the problem of recognition of object manipulation actions. This is a challenging task for real everyday actions, as the same object can be grasped and moved in different ways depending on its functions and geometric constraints of the task. We propose to leverage grasp and motion-constraints information, using a suitable representation, to recognize and understand action intention with different objects. We also provide an extensive experimental evaluation on the recent Yale Human Grasping dataset consisting of large set of 455 manipulation actions. The evaluation involves a) Different contemporary multi-class classifiers, and binary classifiers with one-vs-one multi-class voting scheme, and b) Differential comparisons results based on subsets of attributes involving information of grasp and motion-constraints. Our results clearly demonstrate the usefulness of grasp characteristics and motion-constraints, to understand actions intended with an object.\",\n \"Title: Reactive Obstacle Avoidance for Highly Maneuverable Vehicles Based on a Two-Stage Optical Flow Clustering.\\nYear: 2017\\n\\nAbstract: This paper proposes a reactive obstacle avoidance approach based solely on image data from a monocular camera stream. By clustering and analyzing the optical flow, this approach is able to identify potential collisions with dynamic obstacles. Epipolar geometry is exploited to derive velocity commands that ensure a collision-free path for a highly maneuverable autonomous vehicle via a real-time opt...\",\n \"Title: Monocular Navigation in Large Scale Dynamic Environments.\\nYear: 2017\\n\\nAbstract: present a processing technique for a robust reconstruction of motion properties for single points in large scale, dynamic environments. assume that the acquisition camera is moving and that there are other independently moving agents in a large environment, like road scenarios. The separation of direction and magnitude of the reconstructed motion allows for robust reconstruction of the dynamic state of the objects in situations, where conventional binocular systems fail due to a small signal (disparity) from the images due to a constant detection error, and where structure from motion approaches fail due to unobserved motion of other agents between the camera frames. We present the mathematical framework and the sensitivity analysis for the resulting system.\",\n \"Title: A vectorized Levenberg-Marquardt model fitting algorithm for efficient post-processing of cardiac T1 mapping MRI.\\nYear: 2018\\n\\nAbstract: We have proposed a vectorized curve fitting algorithm allowing spatial regularization, which could improve the robustness of the curve fitting, especially for myocardial T mapping with SR sequences.\",\n \"Title: Interaction-Aware Probabilistic Behavior Prediction In Urban Environments\\nYear: 2018\\n\\nAbstract: Planning for autonomous driving in complex, urban scenarios requires accurate prediction of the trajectories of surrounding traffic participants. Their future behavior depends on their route intentions, the road-geometry, traffic rules and mutual interaction, resulting in interdependencies between their trajectories. We present a probabilistic prediction framework based on a dynamic Bayesian network, which represents the state of the complete scene including all agents and respects the aforementioned dependencies. We propose Markovian, context-dependent motion models to define the interaction-aware behavior of drivers. At first, the state of the dynamic Bayesian network is estimated over time by tracking the single agents via sequential Monte Carlo inference. Secondly, we perform a probabilistic forward simulation of the network's estimated belief state to generate the different combinatorial scene developments. This provides the corresponding trajectories for the set of possible, future scenes. Our framework can handle various road layouts and number of traffic participants. We evaluate the approach in online simulations and real-world scenarios. It is shown that our interaction-aware prediction outperforms interaction-unaware physics-and map-based approaches.\",\n \"Title: Classifying Object Manipulation Actions based on Grasp-types and Motion-Constraints.\\nYear: 2018\\n\\nAbstract: In this work, we address a challenging problem of fine-grained and coarse-grained recognition of object manipulation actions. Due to the variations in geometrical and motion constraints, there are different manipulations actions possible to perform different sets of actions with an object. Also, there are subtle movements involved to complete most of object manipulation actions. This makes the task of object manipulation action recognition difficult with only just the motion information. We propose to use grasp and motion-constraints information to recognise and understand action intention with different objects. We also provide an extensive experimental evaluation on the recent Yale Human Grasping dataset consisting of large set of 455 manipulation actions. The evaluation involves a) Different contemporary multi-class classifiers, and binary classifiers with one-vs-one multi- class voting scheme, b) Differential comparisons results based on subsets of attributes involving information of grasp and motion-constraints, c) Fine-grained and Coarse-grained object manipulation action recognition based on fine-grained as well as coarse-grained grasp type information, and d) Comparison between Instance level and Sequence level modeling of object manipulation actions. Our results justifies the efficacy of grasp attributes for the task of fine-grained and coarse-grained object manipulation action recognition.\",\n \"Title: Isotropic Reconstruction of MR Images Using 3D Patch-Based Self-Similarity Learning.\\nYear: 2018\\n\\nAbstract: Isotropic three-dimensional (3D) acquisition is a challenging task in magnetic resonance imaging (MRI). Particularly in cardiac MRI, due to hardware and time limitations, current 3D acquisitions are limited by low-resolution, especially in the through-plane direction, leading to poor image quality in that dimension. To overcome this problem, super-resolution (SR) techniques have been proposed to r...\",\n \"Title: GPU implementation of Levenberg-Marquardt optimization for Ti mapping\\nYear: 2017\\n\\nAbstract: T\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n mapping is an emerging MRI research tool to characterize diseased myocardial tissue. The T\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</sub>\\n map is generated by fitting an exponential relaxation curve to the acquired image data. Levenberg-Marquardt algorithm is a standard way to solve this nonlinear curve fitting problem. However, the execution on the standard CPU can be time-consuming and incompatible with clinical routine. In this paper, a GPU implementation is performed to reduce the computation time of the standard T\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n mapping. In addition, a new vectorized approach is proposed to include spatial regularization in the curve fitting process to improve the robustness. The GPU implementation is validated on NVIDIA K42000 GPU using cardiac T1 data from 16 volunteers. The computation time shows significant decrease in both pixel-wise and vectorized curve fitting. The pixel-wise curve fitting is accelerated by a factor of 30+ compared to the standard sequential C code and the vectorized curve fitting is improved by a factor of 47 and 38 for 3-parameter and 2-parameter curve fitting compared to the Matlab code.\",\n \"Title: Context-Aware 3D Visualization of the Dynamic Environment\\nYear: 2019\\n\\nAbstract: We present a graphical interface that provides context-dependent information about possible interactions with a complex cluttered environment, which can be used as a video overlay system in Head Mounted Devices (HMDs) in Augmented Reality applications. The system identifies task relevant objects in a cluttered scene, learns the typical interaction patterns with them in a teaching phase, and supports the user with information about the object functionality and handling in the interaction phase. The underlying systen is capable of identification of objects in cluttered environment, providing information about possible task-dependent grasps, tracking object motion with high frame-rate and prediction of possible actions from a learned action graph that represents possible handling variants for a specific object. The system can be used to train a novice in an unknown environment providing expert knowledge. We present our implementation of the system in a service scenario of a kitchen environment, where the system supports the user while performing the actions.\",\n \"Title: Robust Event Detection based on Spatio-Temporal Latent Action Unit using Skeletal Information\\nYear: 2021\\n\\nAbstract: This paper proposes a novel dictionary learning approach to detect event anomalities using skeletal information extracted from RGBD video. The event action is represented as several latent action atoms and composed of latent spatial and temporal attributes. We aim to construct a network able to learn from few examples and also rules defined by the user. The skeleton frames are clustered by an initial K-means method. Each skeleton frame is assigned with a varying weight parameter and fed into our Gradual Online Dictionary Learning (GODL) algorithm. During the training process, outlier frames will be gradually filtered by reducing the weight that is inversely proportional to a cost. To strictly distinguish the event action from similar actions and robustly acquire its action units, we build a latent unit temporal structure for each sub-action. We validate the method at the example of fall event detection on NTU RGB+D dataset, because it provides a benchmark available for comparison. We present the experimental validation of the achieved accuracy, recall, and precision. Our approach achieves the best performance in precision and accuracy of human fall event detection, compared with other existing dictionary learning methods. Our method remains the highest accuracy and the lowest variance, with increasing noise ratio.\",\n \"Title: Direct Image Based Traffic Junction Crossing System for Autonomous Vehicles\\nYear: 2021\\n\\nAbstract: One of the most common traffic scenario when navigating in urban area is the traffic junction. Crossing a traffic junction is not trivial for an autonomous vehicle as it needs to perform both scene understanding and decision making tasks. In this work we introduce a two-stage vision-based system for an autonomous vehicle that is capable of deciding when to cross a traffic junction safely. The firs...\",\n \"Title: Estimating Dense Optical Flow of Objects for Autonomous Vehicles\\nYear: 2021\\n\\nAbstract: Autonomous vehicles need to be able to perceive both the presence and motion of objects in the surrounding environment to navigate in the real world. In this work, we propose to solve the tasks of identifying objects and estimating the corresponding motion by viewing them as a single unified task known as instance flow. Instance flow provides the pixel-wise instance mask of an object and the dense optical flow within it. To achieve this, we extended the state of the art object detection model to include a dense optical flow estimator. The estimator is used to estimate the optical flow for each region of interest only, instead of the entire image. We tested the approach by carrying out experiments on publicly available datasets for autonomous driving research, VKITTI, KITTI and HD1K. Furthermore, we also introduced a new instance flow quality metric to evaluate the instance flow estimation.\",\n \"Title: A Dual Doctor-Patient Twin Paradigm for Transparent Remote Examination, Diagnosis, and Rehabilitation\\nYear: 2021\\n\\nAbstract: The need for comprehensive telemedicine solutions is becoming increasingly relevant due to challenges associated with the ageing population, the increasing shortage of healthcare providers, and, more recently, the global pandemic. Existing solutions primarily focus on, e.g., electronic medical records, audiovisual connections, and, in some cases, robotic systems with very basic capabilities. Here we present a fundamentally new, holistic approach to a remote doctor visit, which enables transparent remote examination, anomaly detection, diagnosis, and rehabilitation. Our dual doctor-patient twin paradigm involves two robotic systems: one representing the doctor to the patient (\\\"GARMI\\\") and one representing the patient to the doctor (\\\"MUCKI\\\"). Through bidirectional telepresence control, this system enables transparent, natural, remote haptic interaction between doctor and patient. The control, interaction, and knowledge transfer to the doctor is enhanced by AI-based visual motion and facial expression analysis as well as a digital twin of the patient. Thus, each stage of a doctor visit can be replicated in the context of telemedicine and shared autonomy: from first assessment to observation-based and remote physical examination, to a better-informed doctor diagnosis and robot-assisted telerehabilitation.\",\n \"Title: Joint prediction of monocular depth and structure using planar and parallax geometry\\nYear: 2022\\n\\nAbstract: •Joint prediction of depth and structure.•A promising plane and parallax pipeline.•Enhance depth prediction on thin objects and edges.•Enhance structure prediction at epipole and without ego motion.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":71,"string":"71"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":258,"string":"258"}}},{"rowIdx":259,"cells":{"question_id":{"kind":"string","value":"Zhaolong Ning"},"question":{"kind":"string","value":"Generate an abstract for the title \"Social-oriented adaptive transmission in wireless ad hoc networks\" using the following items: 1. Cooperation \n2. Social-oriented adaptive transmission \n3. Double auction-based social awareness mechanism \n4. Relay-aided transmissions \n5. Significant advantages in social welfare and throughput improvement."},"answer":{"kind":"string","value":"Cooperation among nodes plays an important role in the commercial development of wireless networks. Efficient cooperation should include not only encouraging selfish nodes to forward packets for one another but also selecting optimal transmission methods. Therefore, in this paper, in order to improve network performance, we propose a social-oriented adaptive transmission scheme for wireless ad hoc networks. Firstly, next-hop node for each transmission is decided by a double auction-based social awareness mechanism. Then in the case of relay-aided transmissions, optimal relaying method is selected by jointly considering network coding and spectrum spatial reuse. Simulation results demonstrate that the proposed scheme has significant advantages in social welfare and throughput improvement."},"correct_answer":{"kind":"string","value":"Cooperation among nodes plays an important role in the commercial development of wireless networks. Efficient cooperation should include not only encouraging selfish nodes to forward packets for one another but also selecting optimal transmission methods. Therefore, in this paper, in order to improve network performance, we propose a social-oriented adaptive transmission scheme for wireless ad hoc networks. Firstly, next-hop node for each transmission is decided by a double auction-based social awareness mechanism. Then in the case of relay-aided transmissions, optimal relaying method is selected by jointly considering network coding and spectrum spatial reuse. Simulation results demonstrate that the proposed scheme has significant advantages in social welfare and throughput improvement."},"documents":{"kind":"list like","value":["Title: Markov-based vertical handoff decision algorithms in heterogeneous wireless networks\nYear: 2014\n\nAbstract: In this paper, we propose a received signal strength (RSS)-based single-attribute handoff decision algorithm at first, and investigate handoff decision model based on connection lifetime, which can keep mobile terminals (MTs) staying long enough in the preferred network. Since the preferred quality of service (QoS) parameters may be distinct among different MTs, we then formulate the vertical handoff decision problem as a Markov decision process, with the objectives of maximizing the expected total reward and minimizing average number of handoffs. A reward function is constructed to assess the QoS during each connection, and the G1 and entropy methods are applied in an iterative way, by which we can work out a stationary deterministic handoff decision policy. Numerical results demonstrate the superiority of our proposed schemes compared with other existing algorithms.","Title: Communication Networks Survivable routing algorithm with mixed shared protection in fault-tolerant GMPLS multi-layered optical networks\nYear: 2010\n\nAbstract: In this paper, we studied survivability in general multi-protocol label switching (GMPLS) multi-layered optical networks and proposed a novel mixed shared protection algorithm (MSPA) based on the integrated layered graph (ILG) to tolerate single-fibre link failure. The ILG is composed of one virtual topology layer (VTL), corresponding to IP/MPLS layer; multiple wavelength-plane layers (WPLs), corresponding to the wavelength-division multiplexing (WDM) optical layer; and some virtual links that connect the VTL to each WPL in order to solve the problem on routing, wavelength assignment and low-speed traffic grooming. For every connection request, the MSPA first computes a single-hop or multi-hop label switching path (LSP) pair, involving a working LSP and a physical link-disjoint backup LSP in the VTL. If the LSP pair is not found in the VTL, the MSPA computes the new LSP pair in the WPL. Conversely, if the new LSP pair is not detected in the WPL, the MSPA computes the hybrid multi-hop LSP pair in the ILG. In the MSPA, if the two working LSPs are in physical link-disjoint, their corresponding backup LSPs can share the backup bandwidth. In addition, the working LSPs and the backup LSPs can also share the same mixed of wavelength, in which the different bandwidths can be assigned to different working and backup LSPs. Simulation results show that, compared to previous algorithm, the MSPA can obtain a better bandwidth utilisation ratio (BUR) with a lower blocking probability. Copyright (C) 2010 John Wiley & Sons, Ltd.","Title: Joint scheduling and routing algorithm with load balancing in wireless mesh network\nYear: 2012\n\nAbstract: Wireless mesh network (WMN) is a promising solution for last mile broadband internet access. Mesh nodes or mesh routers are connected via wireless links to form a multi-hop backbone infrastructure and improving throughput is the primary goal. While previous works mainly focused on either link level protocol design or complex mathematical model, in this paper, we investigate the performance gains from jointly optimizing scheduling and routing in a multi-radio, multi-channel and multi-hop wireless mesh network. Then, two optimization objectives are addressed by considering wireless media contention and spatial multiplexing. The first objective is to maximize throughput by exploiting spatial reuse while the second one is to ensure fairness among different links. We design a cross-layer algorithm by considering both MAC layer and network layer. Simulation results show that our joint optimization algorithm can significantly increase throughput as well as fairness.","Title: Joint power control and spectrum access in cognitive radio networks.\nYear: 2014\n\nAbstract: Cognitive Radio (CR) is proposed to overcome the problem of spectrum underutilization and congestion caused by the increasing demand of wireless services and applications. It is still a challenge to improve the spectrum efficiency of the secondary network for Secondary (unlicensed) Users (SUs) and avoid imposing interference to the Primary (licensed) Users (PUs). In this paper, we propose a joint power control and spectrum access scheme for the CR network. By addressing the power allocation problem and exploiting a Dynamic Spectrum Access (DSA) scheme (which is based on the power allocation and also aims at improving the secondary network throughput) from a cooperative-game perspective, our joint scheme can improve the throughput of the secondary network and guarantee the SUs׳ fairness, without imposing overlarge interference to the PUs. Numerical results reflect that, compared with previous studies, our joint power control and spectrum access scheme presents advantages in comprehensive performance (e.g., spectrum efficiency, fairness and throughput). Beyond a theoretical framework, we solve the optimization problem with the Differential Evolution (DE) algorithm which is more feasible to be implemented in practice.","Title: Subcarrier allocation in multi-hop orthogonal frequency division multiple access wireless networks\nYear: 2014\n\nAbstract: Orthogonal frequency division multiplexing (OFDM) has been widely considered as a key technique for next generation mobile communication systems. Meanwhile, relaying technologies can improve users' quality of service, increase network capacity and enlarge cellular coverage at a low cost. In this paper, we focus on subcarrier allocation and utilization in multi-hop OFDM access (OFDMA) wireless networks, and propose two efficient subcarrier allocation schemes aiming to increase network throughput and subcarrier utilization. The first scheme selects suitable links for data transmission from base stations to terminals at the beginning. Then, interference-free links are included into the same group for network resource reuse. For the purpose of global optimization, we propose a Tabu-based searching algorithm as the second subcarrier allocation scheme. Simulation results demonstrate that our proposed algorithms outperform other schemes in both network throughput and subcarrier utilization.","Title: A novel scheduling algorithm for physical-layer network coding under Markov model in wireless multi-hop network\nYear: 2013\n\nAbstract: Physical-layer network coding (PNC) is a promising approach for wireless networks: it allows nodes to transmit simultaneously and encode packets by superposing signals at the physical layer, which can improve throughput. Because of the difficulty in scheduling simultaneous transmissions, we propose an opportunistic scheduling algorithm in the media access control (MAC) layer and analyze the achievable throughput of the Denoise-and-Forward (DF) PNC scheme for both symmetric and asymmetric channel statuses, where random errors may occur for both BPSK and QPSK modulation techniques. Simulation results show that our algorithm cannot only improve throughput but can also adapt to varying channel conditions. It is further revealed that for the same throughput, our algorithm is more power-efficient with an asymmetric channel status than with a symmetric channel status.","Title: A channel estimation based opportunistic scheduling scheme in wireless bidirectional networks\nYear: 2014\n\nAbstract: Generally speaking, there are two assumptions in the previous bidirectional networks. The first one is assuming that no direct transmission paths exist between the source and destination nodes due to high shadow fading or large separation. The second one is assuming that either channel parameters are pre-established or perfect global channel state information (CSI) can be obtained by the relay nodes. In this paper, we get rid of these limitations and estimate channel gains for both analog network coding (ANC) and time division broadcasting (TDBC) schemes based on outage probability. As the channel gain of each link varies from time to time in wireless networks, we first estimate the channel gain according to outage probability, then propose an opportunistic scheduling scheme to optimize the sum rate values by maximizing the minimum link transmission rate. Simulation results are presented to demonstrate the effectiveness of our channel estimation scheme, and the performance of our proposed opportunistic scheduling scheme is compared with the round robin scheduling (RRS) scheme for both ANC and TDBC schemes.","Title: Link stability estimation based on link connectivity changes in mobile ad-hoc networks\nYear: 2012\n\nAbstract: Link stability issue is significant in many aspects, especially for the route selection process in mobile ad-hoc networks (MANETs). Most previous works focus on the link stability in static environments, with fixed sampling windows which are only suitable for certain network topologies. In this paper, we propose a scheme to estimate the link stability based on link connectivity changes, which can be performed on the network layer, without the need of peripheral devices or low layer data. We adopt a variable sized sampling window and propose a method to estimate the link transition rates. The estimation scheme is not restricted to specific network topologies or mobility models. After that, we propose a routing method which adjusts its operating mode based on the estimated link stability. Simulation results show that the proposed scheme can provide correct estimation in both stationary and non-stationary scenarios, and the presented routing protocol outperforms conventional routing schemes without link stability estimation.","Title: Deployment of survivable fiber-wireless access for converged optical and data center networks.\nYear: 2014\n\nAbstract: As a promising solution for the bandwidth bottleneck of Data Center (DC) network, the converged optical and DC networks have gained an increasing popularity due to their advantages in rich bandwidth and high reliability. Although the converged optical and DC networks bring the opportunity for high-speed transmission of DC traffic, they also impose more severe challenge on the survivability design, because the network component failure will cause greater data loss. Some works focus on the survivability of core network for the convergence of optical and DC networks and remain less touched on that of access network. In fact, access network plays an important role in the reliable transmission of the traffic between end-users and DC, which accounts for considerable portion of all DC traffic. However, since the vulnerability to component failure, the traditional Passive Optical Network (PON) may no longer satisfy the higher survivability requirement. As an emerging broadband access technology, Fiber-Wireless (FiWi) may be a preferable candidate for the survivable access of converged optical and DC networks. In FiWi access network, the Wireless Mesh Network (WMN) at front-end can protect the Passive Optical Network (PON) at back-end by wirelessly rerouting. This paper focuses on the deployment of survivable FiWi access network against single distribution fiber failure, which is a typical failure scenario in optical access network. We propose a new protection approach called Wireless Rerouting with Backup Radios (WRBR) for the deployment of survivable FiWi access network. In WRBR, we deal with the optimization of wireless routers placement and backup radios configuration. Both Integer Linear Programming (ILP) and heuristic approach are proposed, aiming to minimize the deployment cost. Simulation results demonstrate the advantage of WRBR in saving deployment cost of FiWi access for converged optical and DC networks over the previous works.","Title: CITS 2017 general chairs' message\nYear: 2017\n\nAbstract: Welcome to the 2017 International Conference on Computer, Information and Telecommunication Systems (CITS 2017). This year's conference marks the sixth CITS, which is being held on annual basis.","Title: Interference-aware spectrum sensing mechanisms in cognitive radio networks\nYear: 2015\n\nAbstract: Throughput vs. spectrum sensing time under high (left) and moderate (right) usage of spectrum.Display Omitted Study spectrum sensing mechanisms by the optimization of network parameters and strategies.The proposed mechanisms have fewer sensing overhead.SUs can access into the spectrum holes efficiently, and transmit with a low power. This paper focuses on the spectrum sensing mechanisms, which could improve network throughput through the sensing strategy optimization and cooperative spectrum sensing methods. In order to guarantee an integrated and effective research, we take the whole channel scenarios into consideration, i.e., Single Secondary user with Single and Multiple Channels (SSSC and SSMC), Multiple Secondary users with Single and Multiple Channels (MSSC and MSMC). Moreover, according to the specific feature of each scenario, different sensing methods are adopted, i.e., optimal sensing period to maximize network throughput for SSSC, a novel sensing method to minimize searching time for SSMC, partial cooperative spectrum sensing mechanism for MSMC, and setting a spectrum pool in the fusion center to record the channel states for MSMC. Simulation results demonstrate that our methods can improve spectrum efficiency, network throughput and channel utilization, especially when the spectrum is utilized inadequately.","Title: A novel adaptive spectrum allocation scheme for multi-channel multi-radio wireless mesh networks\nYear: 2015\n\nAbstract: The rapidly developed wireless services and applications have an increasing demand of spectrum resource, which is actually limited. Therefore, how to allocate spectrum resource effectively for network throughput improvement is an urgent issue. Although the utilization of spectrum can be enhanced by link scheduling for spatial reuse, Network Coding (NC) for broadcast transmission, multicast transmission and multi-channel multi-radio techniques, their interactions cannot be ignored. This is because on one hand, the achieved network performance by NC is strongly dependent on the MAC layer, and greedy NC method may in fact reduce network throughput owing to the reduction of spectrum spatial reuse. On the other hand, channel assignment faces more challenges brought by NC and multicast transmission since the broadcast or multicast links are dominated by the link with the worst channel state. In order to utilize the spectrum resource adaptively while not bringing additional constraints, we present a two-phase solution approach. On the first step, we formulate the NC-aware scheduling scheme to an optimization problem, by which the interference-free links are allocated into the same link set and can be activated in the same time slot and channel. Then, we assign different channels to the link sets according to the radio constraints in a heuristic method, which can further increase the utilization of spectrum resource. Finally, simulation results demonstrate that our proposed method can largely increase the utilization of spectrum resource and improve network throughput.","Title: Integration of scheduling and network coding in multi-rate wireless mesh networks: Optimization models and algorithms\nYear: 2016\n\nAbstract: In order to fully utilize spectrum resource in wireless mesh networks (WMNs), we propose a combination of some popular communication techniques, including link scheduling, spatial reuse, power and rate adaptation and network coding (NC), to activate as many transmission links as possible during one scheduling period, so that the total scheduling length can be minimized and network throughput can be maximized. Different from previous studies, we consider the interplay among these techniques and present an optimal NC-aware link scheduling mechanism in multi-rate WMNs, which relies on the enumeration of all possible schedules. Due to the high computational complexity of our proposed model, we utilize a column generation (CG)-based method to resolve the optimization problem and decompose it into a master problem (MP) and a pricing problem (PP). Furthermore, we present a distributed power control algorithm for PP, by which the computational complexity of the CG-based scheme can be largely reduced. Simulation results demonstrate the superiority of our method under various network situations.","Title: Design of Dynamic Traffic Grooming Algorithm in Software-Defined Wireless Mesh Networks\nYear: 2015\n\nAbstract: Software-Defined Networking (SDN) separates the network control plane from the packet forwarding plane, and provides the upper applications with an global view of the distributed networks state. By making the network device software programmable, this newly emerging networking paradigm can contribute to change the large and highly complex situation of current networks protocol architecture. SDN enabled Wireless Mesh Networks (WMNs) will apply SDN technology into WMNs. By separating network control logic from data forwarding, automatic control and update functions would be achieved by software-driven control logic, which improves network performance and shortens the cycle of network innovation. Traffic engineering problem involves in the task of mapping network traffic distribution to existing physical topology. It can control network resources utilization and fair traffic allocation, which will optimize the utilization of network resources, and solve the imbalance problem of network resources, so that the network will reach a high degree of reliability, robustness and operability. Therefore, the design of dynamic traffic grooming algorithm in SDN enabled Wireless Mesh Networks is of important theoretical significance and practical value. This article focuses on traffic engineering technology in software defined networking. Aiming at the dynamic routing problem, the SDN controller dynamic traffic grooming algorithm is designed, which takes into account both the path length and link utilization to determine routing establishment, so as to achieve the network load balance and reduce the network congestion. Simulation results demonstrate that our proposed dynamic traffic grooming algorithm performs better in terms of average end-to-end throughput, average end-to-end delay and packet loss probability than traditional scheme.","Title: A Dynamic Cooperative Monitor Node Selection Algorithm in Wireless Mesh Networks\nYear: 2015\n\nAbstract: Wireless Mesh Network (WMN) is developed as an emerging key solution for wireless broadband connectivity through a flexible and cost-effective way. However, due to the lack of a physical line of defense, the security in such a network is a big concern. Intrusion Detection System (IDS) is considered as one of the most effective security mechanisms in WMN. Traditionally, IDS is operated on the monitor nodes that cooperatively identify and assess intrusions by analyzing their collected network data. Therefore, most IDS mechanisms need to choose a large number of monitor nodes for good rapidity and accuracy, which increases overhead and degrades network performance. In this paper, we propose a dynamic cooperative monitor node selection scheme based on social network analysis to solve the above issue. In the scheme, we choose the monitor nodes according to their influence in the network, which is evaluated by the relationship among the nodes and the analysis of mutual information. Then, the nodes with similar information are divided into the same monitor area. Simulation results show that the proposed scheme can effectively reduce network cost compared with the traditional node section schemes.","Title: A Novel Hybrid Routing Forwarding Algorithm in SDN Enabled Wireless Mesh Networks\nYear: 2015\n\nAbstract: As an essential part of next generation Internet, Wireless Mesh Networks (WMNs) have attracted much research attention due to its potential advantages including low up-front cost, ease of deployment, enhanced capacity and service coverage. However, the inherit features of wireless multi-hop networks have put forward a severe challenge for traffic engineering problem. Conventional traffic engineering techniques either locally manipulate network traffic or adopt unreliable best-effort delivery mechanism. Software Defined Networking (SDN) is a new networking paradigm that separates the network control plane from the packet forwarding plane and provides applications with an abstracted centralized view of the distributed network state. A logically centralized controller that has a global network view is responsible for all the control decisions and it communicates with the network-wide distributed forwarding elements via standardized interfaces. Considering the current price of SDN equipments and deployment cost, this paper proposes an idea that gradually increases the number of SDN forwarding element in the networks. In other words, partly deployment of the SDN forwarding element in the networks can achieve fast forwarding traffic. On this basis, a new traffic engineering algorithms named Hybrid Routing Forwarding Algorithm (HRFA) which is based on SDN forwarding and OSPF (Open Shortest Path First) protocol is designed. This hybrid routing scheme divides the network nodes into conventional nodes and SDN forwarding elements (SDN-FE), and chooses effective forwarding strategies for different network elements, which will improve the overall performance of the networks. In order to verify the performance of the proposed algorithms, a number of simulation experiments are carried out in the NS-2 simulation platform. The results show that compared with the traditional routing forwarding method, HRFA can well increase the normalized throughput, and reduce the delay and packet loss.","Title: Hierarchic Topology Management by Decision Model and Smart Agents in Space Information Networks\nYear: 2015\n\nAbstract: Space information network, which is envisioned as a new type of self-organizing networks constituted by information systems of land, sea, air, and space, has attracted tremendous interest recently. In this paper, to improve the data delivery performance and the network scalability of space information networks, a new hierarchic topology management scheme based on decision model and smart agents is proposed. Different from the schemes studied in mobile ad hoc networks and wireless sensor networks, the proposed algorithm in space information networks introduces a decision model based on analytic hierarchy process (AHP) to first select cluster heads, and then forms non-overlapping k-hop clusters. The proposed dynamical self-maintenance mechanisms take not only the node mobility but also the cluster equalization into consideration. Smart mobile agents are used to migrate and duplicate functions of cluster heads in a recruiting way, besides of cluster merger/partition disposal, reaffiliation management and adaptive adjustment of information update period. Simulation experiments are performed to evaluate the performance of the proposed algorithm in terms of network scalability, overhead of clustering and reaffiliation frequency. It is shown from the analytical and simulation results that the proposed hierarchic topology management algorithm significantly improves the performance and the scalability of space information networks.","Title: A Trust-Based User Assignment Scheme in Ad Hoc Social Networks\nYear: 2015\n\nAbstract: Although cooperation among individuals plays a key factor in the commercial development of wireless networks, trust is an important factor due to the uncertainty and uncontrollability caused by the self-organizing character of different entities. In this paper, we present a trust-based user assignment scheme by considering node sociality, the reason behind is that effective user assignment should not only build a reliable system basing on the behavior of network individuals, but also encourage selfish nodes to forward packets for one another. At first, a model for trustworthiness management is built up by considering social relationship. Then, user assignment for each transmission is decided by a double auction-based mechanism. Simulation result demonstrates that our scheme is able to obtain better network performance than the existing method in link connectivity and social welfare.","Title: PNCOIRank: Evaluating the Impact of Scholarly Articles with Positive and Negative Citations.\nYear: 2016\n\nAbstract: Evaluating the impact of an article is a significant topic and has attracted extensive attention. Citation-based assessment methods currently face a limitation, i.e. the anomalous citations patterns still remain poorly understand. To remedy this drawback, we propose a Positive and Negative Conflict of Interest (COI)-based Rank algorithm, named PNCOIRank, to acquire positive COI, negative COI, positive suspected COI and negative suspected COI relationships. We investigate the citation relationships by the following scholarly factors: citing times, the interval of citing time, collaboration times, the interval of collaboration time, and team of citing authors with the purpose of weakening the COI relationships in citation network. A weighted PageRank is finally constructed and employed, with HITS algorithm to assess the impact of articles. Through experiments on American Physical Society (APS) dataset, we show that PNCOIRank significantly outperforms the existing methods in terms of recommendation intensity.","Title: Location-Recommendation-Aware Virtual Network Embedding in Energy-Efficient Optical-Wireless Hybrid Networks Supporting 5G Models.\nYear: 2016\n\nAbstract: Given the possibility of ubiquitous 5G wireless access, location data bridge the gap between the physical world and digital online social networking services and also reflect user preferences and even interdependence among users. Owing to this interdependence, the advertiser can push corresponding products to users according to location recommendations, i.e., advertisement targeting. To achieve this mobile cloud computing service, after moving the computing capacity away from end devices to data centres (DCs), the converged infrastructure integrating optical metro and ubiquitous wireless access technologies is proposed in accordance with the 5G model. To minimize energy consumption, we propose a novel design framework of location-recommendation-aware virtual network embedding. This design framework determines the interdependency among user groups so that we can embed the virtual networks owned by user groups with a high interdependence into the same DC of the substrate optical-wireless hybrid infrastructure. Thus, the adviser can locally push the corresponding products to user groups at a single DC instead of consuming a large amount of energy to build inter-DC paths. The simulation results show that our design framework has greater energy efficiency and more profitable advertisement targeting compared with the benchmark, and the result of our heuristic is very close to the upper bound.","Title: Geo-Social Distance-Based Data Dissemination for Socially Aware Networking.\nYear: 2016\n\nAbstract: The Internet of Things (IoT), which could connect everything in the world, is promising for the realization of smart cities. However, vehicles connected in the IoT challenges data collection and transmission. Socially aware networking is an emerging paradigm for high-efficiency data dissemination. Existing protocols take advantage of mobile nodes' social characteristics (e.g., user interest) to improve dissemination performance. However, they have not exploited enough of what relations are valuable between user interests and how these relations can affect the dissemination of social IoTs. This paper takes advantage of interest inclusion and intersection to solve the dissemination problem in a conference scenario. By constructing the structure of the Interest Tree to solely represent the relations of interest inclusion and interest intersection, we integrate vehicles' social factors into their geographical information, and introduce the concept of geo-social distance (GSD) as the basis of the proposed strategy. Simulation results demonstrate the superiority of our presented method by comparing with two other existing protocols in terms of four objective metrics, which include delivery ratio, overhead, hop-count, and average latency.","Title: Who are the Rising Stars in Academia?\nYear: 2016\n\nAbstract: This paper proposes a novel method named ScholarRank to evaluate the scientific impact of rising stars. Our proposed ScholarRank integrates the merits of both statistical indicators and influence calculation algorithms in heterogeneous academic networks. The ScholarRank method considers three factors, which are the citation counts of authors, the mutual influence among coauthors and the mutual reinforce process among different entities in heterogeneous academic networks. Through experiments on real datasets, we demonstrate that our ScholarRank can efficiently select more top ranking rising stars than other methods.","Title: Collaboration Prediction in Heterogeneous Information Networks\nYear: 2015\n\nAbstract: To reveal the information hiding in the scholarly Big Data, relationship analysis among academic entities has been studied from different perspectives in recent years. In this paper, we focus on the problem of collaboration relationship prediction between authors in heterogeneous information networks, and a new method called MACP, i.e., Meta path and author Attribute based Collaboration Prediction model, is proposed to solve this problem. We use a two-phase collaboration probability learning approach. First, topological features with author attributes are extracted from the network, and then a supervised learning algorithm is employed to find the best weight associated with each feature to determine the collaboration relationship. We present the experiments on a real information network, namely the APS network, which shows that our proposed model can generate more accurate results compared with the method only considering structural features.","Title: Social-Oriented Resource Management in Cloud-Based Mobile Networks.\nYear: 2016\n\nAbstract: One of the predominant challenges for cloud-based services is the coordination of resources in the application and network layers to provide adaptive service delivery and an acceptable user experience. This article surveys resource management in cloud-based networks. The authors suggest that consideration of users' social associations can improve link connectivity and service delivery, and that us...","Title: A secure routing scheme based on social network analysis in wireless mesh networks.\nYear: 2016\n\nAbstract: As an extension of wireless ad hoc and sensor networks, wireless mesh networks (WMNs) are employed as an emerging key solution for wireless broadband connectivity improvement. Due to the lack of physical security guarantees, WMNs are susceptible to various kinds of attack. In this paper, we focus on node social selfish attack, which decreases network performance significantly. Since this type of attack is not obvious to detect, we propose a security routing scheme based on social network and reputation evaluation to solve this attack issue. First, we present a dynamic reputation model to evaluate a nodeu0027s routing behavior, from which we can identify selfish attacks and selfish nodes. Furthermore, a social characteristic evaluation model is studied to evaluate the social relationship among nodes. Groups are built based on the similarity of node social status and we can get a secure routing based on these social groups of nodes. In addition, in our scheme, nodes are encouraged to enter into multiple groups and friend nodes are recommended to join into groups to reduce the possibility of isolated nodes. Simulation results demonstrate that our scheme is able to reflect node security status, and routings are chosen and adjusted according to security status timely and accurately so that the safety and reliability of routing are improved.","Title: A Hybrid Mechanism for Innovation Diffusion in Social Networks.\nYear: 2016\n\nAbstract: Innovation diffusion is the process of adopting novel things, which is deemed as the diffusion of human behaviors. Previous studies mainly posit an unclear distinction with information diffusion. However, there exist critical differences in both social and economic areas. Inspired by this observation, we propose a practical method for innovation diffusion based on the process of behavior diffusion, which integrates threshold model with social imitation strategy. The primary goal of our proposed model is to combine individuals' economic as well as social characteristics to study innovation diffusion. The interplay of these two strategies is studied in the context of a coordination game. According to the simulation results on Erdos-Renyi random networks and small-world networks, we find that the conjunction of these two approaches can greatly improve the efficiency of innovation diffusion. In addition, we further study the impacts of varied initial seeds' selection strategies on the overall performance of innovation diffusion using our proposed model.","Title: Toward Efficient 5G Transmission: SER Performance Analysis for Asynchronous Physical-Layer Network Coding.\nYear: 2016\n\nAbstract: People's pursuit of higher quality communication has never ceased, which challenges the layout of 5G networks. Physical-layer network coding (PNC), as a key technology for 5G, supplies a powerful platform through leveraging the broadcast nature of wireless media. However, the symbol error rate (SER) of PNC is not well investigated, which would seriously influence user's quality of experience due to packet loss in wireless environment. In this paper, considering both phase and symbol misalignments, we perform analysis on SER of asynchronous PNC. By assuming part of information is known to the relay, and we derive the lower bound for SER. Afterward, through applying the concept of error vector and eliminating redundant terms, we derive the upper bound for SER. Both the lower and upper bounds are applicable to either multiuser detection-based network coding or belief propagation-based maximum a posteriori decoding. Finally, Monte Carlo simulation verifies our results and demonstrates that the bounds are relatively tight. The analytical results derived in this paper can facilitate future studies of practical and theoretical issues on PNC.","Title: Cooperative Mechanism for Energy Transportation and Storage in Internet of Energy\nYear: 2017\n\nAbstract: To improve the energy conversion ability and well utilize renewable resources, J. Rifkin first put forward the concept of Internet of energy IoE). Although a peer-to-peer energy sharing mechanism is achieved through bi-directional energy transportation, the approach to solving cooperative energy transportation and storage still needs improving. Traditionally, the redundant energy will be wasted if it cannot be consumed by power load. In fact, the redundant energy can be stored to supply power loads in the future. For this end, we investigate cooperative energy transportation and storage for IoEs in terms of problem analysis, algorithm design, and platform development. After demonstrating the feasibility condition and proving the NP-hard of our problem, we derive the optimal solution by the reduction from a classic knapsack problem. We also design novel heuristics followed by different energy storage strategies. In addition, based on software-defined networking (SDN), a complementary platform is developed to make an effective decision for cooperative energy transportation and storage using heuristics above. Both simulation and experimental results demonstrate the effectiveness of our solutions.","Title: CAIS: A Copy Adjustable Incentive Scheme in Community-Based Socially Aware Networking\nYear: 2017\n\nAbstract: Socially aware networking (SAN) is a new communication paradigm, in which the social characteristics of mobile nodes are exploited to improve the performance of data distribution. In SAN, mobile carriers may exhibit selfish behaviors and refuse to relay messages for others for various reasons, such as limited resources (e.g., buffer, energy, and bandwidth) or social relationships. Several incentiv...","Title: Vehicular Social Networks: Enabling Smart Mobility.\nYear: 2017\n\nAbstract: Vehicular transportation is an essential part of modern cities. However, the ever increasing number of road accidents, traffic congestion, and other such issues become obstacles for the realization of smart cities. As the integration of the Internet of Vehicles and social networks, vehicular social networks (VSNs) are promising to solve the above-mentioned problems by enabling smart mobility in modern cities, which are likely to pave the way for sustainable development by promoting transportation efficiency. In this article, the definition of and a brief introduction to VSNs are presented first. Existing supporting communication technologies are then summarized. Furthermore, we introduce an application scenario on trajectory data-analysis-based traffic anomaly detection for VSNs. Finally, several research challenges and open issues are highlighted and discussed.","Title: Social-Oriented Adaptive Transmission in Opportunistic Internet of Smartphones.\nYear: 2017\n\nAbstract: Stable and reliable wireless communication is one of the critical demands for smart cities to connect people and devices. Although intelligent terminals can be leveraged to deliver and exchange data through Internet, poor network coverage and expensive network access challenge the deployment of network infrastructure. In this paper, we propose a social-oriented smartphone-based adaptive transmissi...","Title: Sustainable Strategy for Recycling Edge Devices in Internet of Everything Networks.\nYear: 2017\n\nAbstract: Internet of Everything (IoE) devices have different operation principles, which weakens the network scalability and data interoperability. Virtualization is an economic way of solving this problem. The data-collected by different vendors' sensors-can share the same computing program encapsulated by the Virtual Machine (VM), thus neglecting the physical-layer difference. To eliminate the extreme cost and long delay of transferring VMs to the remote cloud, the Edge Device (ED) preliminary processes its running VMs. Currently, the recycling of IoE devices become a major dilemma for individuals, since it is not simply a matter of concern for environmental damage or a solution to an environmental problem. Therefore, the sustainable strategy for recycling EDs is an important way to safeguard the network sustainability. To improve the recycling efficiency, most of the EDs should be upgraded simultaneously during one batch by migrating their running VMs to others for the service continuity. We investigate the least upgrade batch for recycling EDs in IoE networks. A two-step algorithm called MSBP (Minimized upgrade batch VM Scheduling and Bandwidth Planning) is designed to minimize the number of upgrade batches. Because migrating VM brings the bandwidth consumption along trajectories, MSBP has two strategies-Shortest Trajectory First (STF) and Least Bandwidth Utilization First (LBUF)-of allocating bandwidth and trajectories. The simulation results show that: 1) MSBP has the optimal recycling efficiency (least number of upgrade batches) for EDs; 2) LBUF more effectively mitigates the phenomenon where VM migration trajectories compete for the common link bandwidth, thus achieving a lower negative impact of path contention level on the recycling efficiency; 3) the battery power is not exhausted for the ED functioned as the sensor head of data transferring, thus prolonging the network lifetime. In summary, our solution well improves the network, social, economic and ecological sustainability.","Title: Green Virtual Network Embedding for Collaborative Edge Computing in Environment-Friendly Optical-Wireless Networks.\nYear: 2017\n\nAbstract: To reduce the cost and delay caused by transferring data to the remote cloud, the trend is to design an intelligent Edge Device (ED) for preliminary data processing, i.e., edge computing. Some EDs usually form a group where they wirelessly communicate with each other. Different ED groups are interconnected by optical fiber cables. Through coordinating the use of ED groups, we can perform a collaborative edge computing in a hybrid network where a cost-efficient optical-wireless convergence is achieved by virtualization. In this paper, we use the virtual network to describe one computing-application's requirement for the substrate resource, and we investigate how embed multiple virtual networks onto the common network infrastructure. In our approach, a graph-cutting algorithm is firstly utilized to embed as many virtual networks as possible onto the specified EDs within the same group. However, a single ED group cannot handle all computing applications competing for limited wireless and computing resources. To solve this challenging problem, we transform the virtual networks-impossibly embedded onto the same ED group into new ones processed by ED groups. Simulations results demonstrate the green feature of our solution: 1) the total transmitting power assigned for EDs is effectively reduced using the graph cutting algorithm provided that all of computing applications can be solved by a single ED group; 2) our method accepts more virtual networks with the improvement ratio of 77%, through the coordination of ED groups. In addition, there is a good match between the algorithm result and the optimal number of consumed wavelengths per optical fiber cable.","Title: Poster: Emotion-Aware Smart Tips for Healthy and Happy Sleep.\nYear: 2017\n\nAbstract: People spend up to one-third of lives asleep, and healthy sleep habits can make a big difference in their quality of life. But in modern society, many people have unhealthy sleep diaries and suffer from various sleep disorders, which may result in irregular mood fluctuations or even mental health problems such as anxiety and depression. We propose the Emotion-Aware Smart Tips (EAST), a novel approach that could help to inform users about their irregular emotional states with smart tips to improve their sleep qualities. EAST aims at helping users keep healthy sleep schedules and emotional states by providing smart tips through a novel model that combines multivariate regression, random forest, and neural network to quantify the relations between sleep patterns and emotional states. Prototype implementation and initial experiments of EAST in mobile phones have demonstrated its desired functionality and practicality for real-world deployment.","Title: Joint Encoding and Grouping Multiple Node Pairs for Physical-Layer Network Coding With Low-Complexity Algorithm.\nYear: 2017\n\nAbstract: How to put fifth-generation (5G) into the commercial service by 2020 is still challenging. Since physical-layer network coding (PNC) does not bring unnecessary redundancy and offers satisfactory end-to-end services, it is promising to provide network services in 5G networks. Existing works on PNC mainly focus on the case that two packets are simultaneously sent by a node pair for information excha...","Title: The Role of Positive and Negative Citations in Scientific Evaluation.\nYear: 2017\n\nAbstract: Quantifying the impact of scientific papers objectively is crucial for research output assessment, which subsequently affects institution and country rankings, research funding allocations, academic recruitment, and national/international scientific priorities. While most of the assessment schemes based on publication citations may potentially be manipulated through negative citations, in this paper, we explore the conflict of interest (COI) relationships and discover negative citations and subsequently weaken the associated citation strength. Positive and negative COI- distinguished objective rank algorithm (PANDORA) has been developed, which captures the positive and negative COI, together with the positive and negative suspected COI relationships. In order to alleviate the influence caused by negative COI relationship, collaboration times, collaboration time span, citation times, and citation time span are employed to determine the citing strength; while for positive COI relationship, we regard it as normal citation relationship. Furthermore, we calculate the impact of scholarly papers by PageRank and HITS algorithms, based on a credit allocation algorithm which is utilized to assess the impact of institutions fairly and objectively. Experiments are conducted on the publication data set from American Physical Society data set, and the results demonstrate that our method significantly outperforms the current solutions in recommendation intensity of list R at top-K and Spearman's rank correlation coefficient at top-K.","Title: An Overview On Evaluating And Predicting Scholarly Article Impact\nYear: 2017\n\nAbstract: Scholarly article impact reflects the significance of academic output recognised by academic peers, and it often plays a crucial role in assessing the scientific achievements of researchers, teams, institutions and countries. It is also used for addressing various needs in the academic and scientific arena, such as recruitment decisions, promotions, and funding allocations. This article provides a comprehensive review of recent progresses related to article impact assessment and prediction. The review starts by sharing some insight into the article impact research and outlines current research status. Some core methods and recent progress are presented to outline how article impact metrics and prediction have evolved to consider integrating multiple networks. Key techniques, including statistical analysis, machine learning, data mining and network science, are discussed. In particular, we highlight important applications of each technique in article impact research. Subsequently, we discuss the open issues and challenges of article impact research. At the same time, this review points out some important research directions, including article impact evaluation by considering Conflict of Interest, time and location information, various distributions of scholarly entities, and rising stars.","Title: A Hierarchical Routing Algorithm for Satellite Networks Considering FSO Communication\nYear: 2017\n\nAbstract: Insufficient ground stations promote the emergence of inter-satellite links (ISLs). Nowadays, adopting free space optical (FSO) ISLs has been a new trend for data communications. However, FSO ISLs across the atmosphere may perform worse in adverse weather such as fog or snow. In addition, using ordinary flat routing causes an excessive processing overhead, and diverse quality of experiences (QoEs) cannot be well satisfied. To solve these problems, we propose a Hierarchical Routing protocol for low/medium earth orbit (LEO/MEO) Satellite RF( radio frequency)/FSO Communication Networks (HR-SFCN). The entire network is divided into several LEO-satellite clusters, and each cluster treats the MEO satellite as the manager. To satisfy diverse QoE requirements, we propose the optimization algorithm for data interactions within the cluster. To reduce the processing overhead, we utilize MEO satellites as relay nodes for inter-cluster communications. To guarantee the link availability, we also perform adaptive RF/FSO link switching according to weather conditions. Given a STK(satellite tool kit)-based satellite communication network model, simulation results demonstrate that our HR-SFCN achieves a good trade-off among packet loss rate, path cost and end-to-end delay. Our RF/FSO hybrid system also increases the link availability up to 99.999%.","Title: A cloud-supported cps approach to control decision of process manufacturing: 3D ONoC\nYear: 2017\n\nAbstract: The Cyber-Physical System (CPS) concept is now attracting attention in systems engineering, and it is being applied to a fully automated factory control in processes such as semiconductor fabrication. In this paper, we propose a novel control decision structure for process manufacturing, designated as the 3D Optical Network-on-Chip (ONoC) multi-core system, based on the cloud-supported CPS concept. We first construct a task graph - which includes interconnected Virtual Machines (VMs)-to represent the interaction between industrial-physical processes and cyber states. Given the task graph, the control decision process becomes into the problem of the on-chip VM placement. We then design a highly reliable on-chip VM placement scheduling to find the optimal control strategy while guaranteeing the reliability of the 3D ONoC structure. The simulation results demonstrate that our scheme achieves a higher reliability of the 3D ONoC structure when we make the control decision for process manufacturing.","Title: An Improved Apriori-Based Algorithm For Friends Recommendation In Microblog\nYear: 2018\n\nAbstract: With the rapid development of Internet, the world has come into a new era of network interaction. Internet development in China makes various kinds of software available to users, by which relatives, close friends, and partners can achieve real-time interactions. It is acknowledged that the recommended issues and persons are the most important parts for user experience. This study concentrates on how to provide a recommendation for users with a common interest in Microblog. We first illustrate some recommended algorithms based on data mining, and the implementation process of friend-recommended system is then stated. After that, by integrating the characteristics of the user information, the forwarding and comments on information to associated users, we present an improved Apriori-based algorithm to rank the recommended information with confidence interval. Simulation results demonstrate the superiority and efficiency of our method.","Title: Team Recognition in Big Scholarly Data: Exploring Collaboration Intensity.\nYear: 2017\n\nAbstract: The scale of scholarly data has been expanded due to the fact that scientific productions are increasing rapidly and new scholars affiliate academia incessantly. Scholars are shifting their research patterns from individual research to academic teamwork due to the complexity of scientific issues. In order to achieve higher reputations and better performance, academic teams with leaders are constructed to speed up knowledge sharing and problem solving. It is significant to explore team-based issues with the increasing interests of information exploration in big scholarly data. However, existing academic team definitions are commonly not quantitative, which makes it difficult to identify real academic teams. In this work, we propose a collaboration relationship evaluation index called Collaboration Intensity Index (CII), which is a two-way and quantitative index to evaluate collaboration intensity between two scholars in the network. Then, we construct a new type of co-author network with edges weighted by CII, which differs from the original co-author networks. This network reflects the newly scientific research patterns inside or outside academic teams. Furthermore, we propose TRAC (Team Recognition Algorithm based on CII) to identify academic teams from large co-author networks. Finally, we use DBLP data set, which contains 1,250,440 scholars and 1,575,949 published papers, to identify teams by TRAC. Comparing with fast unfolding algorithm and real team data, the effectiveness of our method can be demonstrated.","Title: Green Survivable Collaborative Edge Computing in Smart Cities.\nYear: 2018\n\nAbstract: As an integrated environment deployed with wired and wireless infrastructures, the smart city heavily relies on the wireless-optical broadband access network. The information flows captured by indoor devices are sent to optical network units through front-end wireless mesh sensor networks (WMNs) and, finally, reach the optical line terminal for industrial/commercial decision making via the passive...","Title: A Collaborative Filtering Recommendation-Based Scheme for WLANs With Differentiated Access Service.\nYear: 2018\n\nAbstract: As the deployment of WLANs becomes extensive, users commonly have to select one access point (AP) for association among multiple available APs. However, the existing AP selection policies are not sufficient enough due to their drawbacks (e.g., imbalanced load and time consuming for association). In this paper, we present a collaborative filtering (CF) recommendation-based AP selection strategy in ...","Title: Vehicular Social Networks: A survey.\nYear: 2018\n\nAbstract: A Vehicular Social Network (VSN) is an emerging field of communication where relevant concepts are being borrowed from two different disciplines, i.e., vehicular ad-hoc networks (VANETs) and mobile social networks (MSNs). This emerging paradigm presents new research fields for content sharing, data dissemination, and delivery services. Based on social network analysis (SNA) applications and methodologies, interdependencies of network entities can be exploited in VSNs for prospective applications. VSNs involve social interactions of commuters having similar objectives, interests, or mobility patterns in the virtual community of vehicles, passengers, and drivers on the roads. In this paper, considering social networking in a vehicular environment, we investigate the prospective applications of VSNs and communication architecture. VSNs benefit from the social behaviors and mobility of nodes to develop novel recommendation systems and route planning. We present a state-of-the-art literature review on socially-aware applications of VSNs, data dissemination, and mobility modeling. Further, we give an overview of different recommendation systems and path planning protocols based on crowdsourcing and cloud-computing with future research directions.","Title: A Social-Aware Group Formation Framework for Information Diffusion in Narrowband Internet of Things.\nYear: 2018\n\nAbstract: Due to the heterogeneous and resource-constrained characters of Internet of Things (IoT), how to guarantee ubiquitous network connectivity is challenging. Although LTE cellular technology is the most promising solution to provide network connectivity in IoTs, information diffusion by cellular network not only occupies its saturating bandwidth, but also costs additional fees. Recently, NarrowBand-I...","Title: SDN-Enabled Social-Aware Clustering in 5G-VANET Systems.\nYear: 2018\n\nAbstract: Nowadays, vehicular applications for traffic safety, traffic efficiency, and entertainment have put forward higher requirements to vehicular communication systems. The fifth-generation (5G) cellular networks are potential to provide high-capacity low-latency communications for vehicles in highly mobile environments. In addition, the IEEE 802.11p-based dedicated short-range communication technology is proposed to form vehicular ad hoc networks (VANETs). Integrating cluster-based VANETs with 5G cellular networks is beneficial for saving scarce spectrum resources, preventing network congestion, and reducing packet loss. However, it is a challenging problem to find an effective clustering algorithm that has high stability adapting to dynamic VANETs. Considering the advantages of software-defined networking (SDN), in this paper, we present an SDN-enabled social-aware clustering algorithm in the 5G-VANET system, which exploits a social pattern (i.e., vehicles' future routes) prediction model in order to enhance the stability of clusters. Each vehicle's movement is modeled as a discrete time-homogeneous semi-Markov model, where the state transition probability and sojourn time probability distribution are inputs and each vehicle's social pattern is output. The predicted social patterns are subsequently used to create clusters so that vehicles in the same cluster tend to share the same routes. Cluster heads are selected based on the metrics of inter vehicle distance, relative speed, and vehicle attributes. We evaluate our algorithm and the results show that it performs better in terms of cluster lifetime and clustering overhead compared with traditional clustering algorithms.","Title: A Survey on Human-Centric Communications in Non-Cooperative Wireless Relay Networks.\nYear: 2018\n\nAbstract: The performance of data delivery in wireless relay networks (WRNs), such as delay-tolerant networks and device-to-device communications heavily relies on the cooperation of mobile nodes (i.e., users and their carried devices). However, selfish nodes may refuse to relay data to others or share their resources with them due to various reasons, such as resource limitations or social preferences. Mean...","Title: AIRank: Author Impact Ranking through Positions in Collaboration Networks.\nYear: 2018\n\nAbstract: Citation is a universally acknowledged way for scientific impact evaluation. However, due to its easy manipulability, simply relying on citation cannot objectively reflect the actual impact of scholars. Instead of citation, we utilize the academic networks, in virtue of their available and abundant academic information, to evaluate the scientific impact of scholars in this paper. Through the collaboration among scholars in academic networks, we notice an interesting phenomenon that scholars in some special positions can access more kinds of information and connect researchers from different groups to promote the scientific collaborations. However, this important fact is generally ignored by the existing approaches. Motivated by the observations above, we propose the novel method AIRank to evaluate the scientific impact of scholars. Our method not only considers the impact of scholars through the mutual reinforcement process in heterogeneous academic networks, but also integrates the structural holes theory and information entropy theory to depict the benefit that scholars obtain via their positions in the network. The experimental results demonstrate the effectiveness of AIRank in evaluating the impact of scholars more comprehensively and finding more top ranking scholars with interdisciplinary nature.","Title: Combinative hypergraph learning in subspace for cross-modal ranking.\nYear: 2018\n\nAbstract: Recent years have witnessed a surge of interests in cross-modal ranking. To bridge the gap between heterogeneous modalities, many projection based methods have been studied to learn common subspace where the correlation across different modalities can be directly measured. However, these methods generally consider pair-wise relationship merely, while ignoring the high-order relationship. In this paper, a combinative hypergraph learning in subspace for cross-modal ranking (CHLS) is proposed to enhance the performance of cross-modal ranking by capturing high-order relationship. We formulate the cross-modal ranking as a hypergraph learning problem in latent subspace where the high-order relationship among ranking instances can be captured. Furthermore, we propose a combinative hypergraph based on fused similarity information to encode both the intra-similarity in each modality and the inter-similarity across different modalities into the compact subspace representation, which can further enhance the performance of cross-modal ranking. Experiments on three representative cross-modal datasets show the effectiveness of the proposed method for cross-modal ranking. Furthermore, the ranking results achieved by the proposed CHLS can recall 80% of the relevant cross-modal instances at a much earlier stage compared against state-of-the-art methods for both cross-modal ranking tasks, i.e. image query text and text query image.","Title: Energy-Latency Tradeoff for Energy-Aware Offloading in Mobile Edge Computing Networks.\nYear: 2018\n\nAbstract: Mobile edge computing (MEC) brings computation capacity to the edge of mobile networks in close proximity to smart mobile devices (SMDs) and contributes to energy saving compared with local computing, but resulting in increased network load and transmission latency. To investigate the tradeoff between energy consumption and latency, we present an energy-aware offloading scheme, which jointly optim...","Title: A Cooperative Quality-Aware Service Access System for Social Internet of Vehicles.\nYear: 2018\n\nAbstract: Because of the enormous potential to guarantee road safety and improve driving experience, social Internet of Vehicle (SIoV) is becoming a hot research topic in both academic and industrial circles. As the ever-increasing variety, quantity, and intelligence of on-board equipment, along with the evergrowing demand for service quality of automobiles, the way to provide users with a range of security...","Title: A Demand-Supply Oriented Taxi Recommendation System for Vehicular Social Networks.\nYear: 2018\n\nAbstract: To realize the construction of intelligent transportation system, data mining based on large-scale taxi traces has become a hot research topic. A crucial direction for analyzing taxi GPS data set is to recommend cruising areas for taxi drivers. Most of the existing researches merely concentrate on how to maximize drivers' profits while overlooking the benefit of passengers. Such imbalance makes the existing solutions do not work well in a real-world environment. In this paper, we construct a recommendation system by jointly considering the profits of both drivers and passengers. Specifically, we first investigate the real-time demand-supply level for taxis and then make an adaptive tradeoff between the utilities of drivers and passengers for different hotspots. At last, the qualified candidates are recommended to drivers based on the analysis results. Simulation results indicate that the constructed recommendation system can achieve a remarkable improvement on the global utility and make equilibrium between the utilities of drivers and passengers, simultaneously.","Title: Novel Framework of Risk-Aware Virtual Network Embedding in Optical Data Center Networks.\nYear: 2018\n\nAbstract: The traffic between geographically distributed data centers (DCs) becomes bandwidth hungry. Since the optical interconnection has a high capacity, the optical data center network (ODCN)-where DCs are located at the edge of the optical backbone-emerges. By virtualization, the virtual networks-representing service requirements-are embedded onto the same part of the substrate ODCN. Each virtual netwo...","Title: A City-Wide Real-Time Traffic Management System: Enabling Crowdsensing in Social Internet of Vehicles.\nYear: 2018\n\nAbstract: As an emerging platform based on ITS, SIoV is promising for applications of traffic management and road safety in smart cities. However, the endto- end delay is large in store-carry-and-forwardbased vehicular networks, which has become the main obstacle for the implementation of large-scale SIoV. With the extensive applications of mobile devices, crowdsensing is promising to enable realtime conten...","Title: Quick Answer for Big Data in Sharing Economy: Innovative Computer Architecture Design Facilitating Optimal Service-Demand Matching.\nYear: 2018\n\nAbstract: In sharing economy, people offer idle social resources to others in a sharing manner. Through community-based online platforms, the people offering services can earn commission while others can enjoy a better life via renting social resources. Consequently, the value-in-use of services is expectedly strengthened within the unit time, although the total amount of social resources remains constant. ...","Title: Heterogeneous visual features integration for image recognition optimization in internet of things.\nYear: 2018\n\nAbstract: •A multimodal deep learning approach for image recognition optimization is proposed.•A back propagation optimization algorithm with shared weights is designed.•Results show our scheme has superior performance on image recognition.","Title: Robust Caching Control In Crowdsourced Content-Centric Mobile Networking\nYear: 2018\n\nAbstract: As the global mobile data traffic grows dramatically in recent years, mobile services are shifting from connection-centric communications to content-centric communications. Content-Centric Networking is a promising clean-slate paradigm with the features of named data and in-network caching. However, the content caching and sharing among mobile clients is not yet considered in Content-Centric Mobile Networking (CCMN). In this paper, to supply a stable high quality of service for content distribution, we design a novel crowdsourced CCMN framework firstly. The vicinal mobile users collaborate with each other by crowdsourcing their caching resources and radio links. Subsequently, we analyze the performance bound of crowdsourced CCMN in perspective of cached data. Furthermore, to guarantee the stability of service quality against user mobility, we propose a robust caching control scheme. We use Kullback-Leibler divergence to characterize user mobility distribution uncertainty and formulate the caching control problem into a chance-constrained robust optimization. By the evaluation results, we can see that the robust caching control mechanism can provide not only a more stable but also higher cache hit ratio than other strategies.","Title: Big Trajectory Data: A Survey of Applications and Services.\nYear: 2018\n\nAbstract: The rapid development of wireless infrastructure and data acquisition technologies contributes to the explosive growth of data, especially trajectory data with rich information. Trajectory data, which records locations of moving objects at certain moments, has long been an important means of studying human behavior and solving traffic problems. In this paper, we mainly introduce the trajectory data from the perspective of applications and services. According to the degree of data structured, we divide the trajectory data into explicit trajectory data and implicit trajectory data, and describe each type in detail. Then, we introduce the applications of trajectory data from travel behavior, travel patterns, and other aspects. Combined with case studies, we provide a description to the services of trajectory data in terms of transportation administration and commercial service. Finally, we focus on challenges in trajectory data, including privacy protection, human mobility causality, and emission reduction.","Title: On-Chip Hardware Accelerator for Automated Diagnosis Through Human-Machine Interactions in Healthcare Delivery.\nYear: 2019\n\nAbstract: The automated diagnosis helps us better understand the complex landscape of diseases, leading to more effective, early and reliable medical diagnosis and therapy. The human-machine interactions in healthcare delivery relying on automated cyber-physical systems (ACPSs) play an important role in the automated diagnosis. Currently, the multicore accelerator used for ACPS has utilized the network-on-c...","Title: Green and Sustainable Cloud of Things: Enabling Collaborative Edge Computing\nYear: 2019\n\nAbstract: The proliferation of IoTs beside the emergence of various cloud services push the horizon of edge computing. By offering cloud capabilities at the network edge closer to mobile devices, edge computing is a promising paradigm to resolve several vital challenges in IoTs, such as bandwidth saturation, energy constraints, low latency transmission, and data security and privacy. To provide a comprehensive understanding of edge computing supported by the integration of IoTs and cloud computing, that is, CoTs, this article first discusses some distinct research directions in CoTs with respect to edge computing. Given the significance of energy efficiency and sustainability of edge deployment in CoTs, we put forward a green and sustainable virtual network embedding framework for cooperative edge computing in wireless-optical broadband access networks. Specifically, we leverage a reliability function to confirm the number of backup edge devices, and embed virtual networks onto the suitable edge devices in CoTs. Finally, several research challenges and open issues are discussed.","Title: A Privacy-Preserving Message Forwarding Framework for Opportunistic Cloud of Things.\nYear: 2018\n\nAbstract: As an emerging communication platform, opportunistic Cloud of Things (CoT) is promising for clients to exchange messages through opportunistic contacts in cloud computing-enabled Internet of Things. Recently, numerous socially aware schemes have been put forward, leveraging users’ social attributes and contact history to predict future contacts with the purpose of improving message forwarding effi...","Title: The Impact Of Digital Alarm Sound To Human Emotions: A Case Study\nYear: 2018\n\nAbstract: In many people's daily life, alarm sounds play an important role, which reflects the fast paced life in the modern society. On most occasions, people uses alarm sounds to wake them up in the morning. Improper alarm sounds may make people feel terrible. In this paper, we mainly propose a smart alarm sound recommendation system and construct an application to study how alarm sounds can impact human emotions. The recommendation system is deployed on the cloud, working with smartphones to deliver smart alarm sounds by considering not only sleep patterns, but also context information such as weather. The designed system can recommend smart alarm sounds to users, orchestrate sensing data collected by multiple sensors on smartphones, and collaborate with the cloud to recommend preferable alarm sounds. An application is developed to demonstrate system effectiveness, which consists of the fore-end on Android OS and the back-end on the cloud. Experiments demonstrate that our system can recommend smart alarm sounds to wake participants up in the morning, and the participants give feedback about their emotional states. The results show that the system can improve people's emotion states by about 14.57%, compared to the traditional alarm sound delivery.","Title: Optimizing Content Dissemination for Real-Time Traffic Management in Large-Scale Internet of Vehicle Systems\nYear: 2019\n\nAbstract: As an application of “smart transport” for Internet of Things, Internet of Vehicle (IoV) has emerged as a new research field based on vehicular ad hoc networks (VANETs). With the development of smart vehicles and the integration of sensors, applications of traffic management and road safety in large-scale IoV systems have drawn great attentions. By sensing events occurred on roads, vehicles can broadcast messages to inform others about traffic jams or accidents. However, the store-carry-and-forward transmission pattern may cause a large transmission delay, making the implementation of large-scale traffic management difficult. In this paper, we put forward a feasible solution to minimize the response time for traffic management service, by enabling real-time content dissemination based on heterogeneous network access in IoV systems. We first design a crowdsensing-based system model for large-scale IoV systems. Then, a cluster-based optimization framework is investigated to provide timely responses for traffic management. Specifically, we estimate the message transmission delay by stochastic theory, which can provide a guideline for the next-hop relay selection in our delay-sensitive routing scheme. Furthermore, network performances are evaluated based on two city-road maps, and performance metrics, containing average delivery delay, average delivery ratio, average communication cost, and access ratio, demonstrate the superiority of our system. Finally, we conclude our work and discuss the further work.","Title: Vehicular Fog Computing: Enabling Real-Time Traffic Management for Smart Cities\nYear: 2019\n\nAbstract: Fog computing extends the facility of cloud computing from the center to edge networks. Although fog computing has the advantages of location awareness and low latency, the rising requirements of ubiquitous connectivity and ultra-low latency challenge real-time traffic management for smart cities. As an integration of fog computing and vehicular networks, vehicular fog computing (VFC) is promising to achieve real-time and location-aware network responses. Since the concept and use case of VFC are in the initial phase, this article first constructs a three-layer VFC model to enable distributed traffic management in order to minimize the response time of citywide events collected and reported by vehicles. Furthermore, the VFC-enabled offloading scheme is formulated as an optimization problem by leveraging moving and parked vehicles as fog nodes. A real-world taxi-trajectory-based performance analysis validates our model. Finally, some research challenges and open issues toward VFC-enabled traffic management are summarized and highlighted.","Title: Appropriate Service Degradability for Virtualized Inter-Data-Center Optical Networks.\nYear: 2018\n\nAbstract: Performing virtualization can further improve the infrastructure utilization of Inter-Data-Center Optical Networks (IDCONs). In virtualized IDCONs, a service requestor subscribes one lightpath for transferring the virtual machine to the specific server in the destination DC. However, the infrastructure overload leads to the denial of services. Thus, we design a novel service degradability (well-intentioned service degradation) framework, in order to minimize the number of service requirements declined by overloads, resulting in the maximal utility of the IDCON provider. We mathematically formulate the problem and determine the most appropriate degradation degree based on microeconomic theory. For heuristic algorithms, the availability-aware bandwidth degradability policy is invoked once there is the optical backbone overload; while for the server overload in DCs, the application-specific virtual machine degradability policy is considered. Finally, the simulation results demonstrate the effectiveness of our heuristic algorithms, and the optimal combination of degradation coefficients is achieved by microeconomic theory and LINGO.","Title: An Interference Coordination-Based Distributed Resource Allocation Scheme in Heterogeneous Cellular Networks.\nYear: 2017\n\nAbstract: As a result of the significant increase of overlapped coverage areas among base stations (BSs), interference coordination in heterogeneous cellular networks (HetCNets) becomes necessary, since interference would degrade network performance and even cause dropped calls. In addition, various types of BSs coexist in HetCNets, and BSs with low power (such as Pico BSs and Femto BSs) are deployed more arbitrarily than those in macrocell BSs (MBSs) so that the traditional anti-interference technologies are not enough in HetCNets. To reduce the interference between MBSs and low-power BSs within the coverage, a novel distributed resource allocation algorithm is proposed. First, an interference graph is established, by which the corresponding orthogonal resources can be assigned to different BSs, and the users can be classified into center and edge users, respectively. After that, users select appropriate resource blocks according to an improved proportional fair algorithm, and BSs distribute transmission power to different resource blocks to enhance network throughput further. Simulation results demonstrate the effectiveness of our proposed scheme in resource allocation and utilization.","Title: Temporal, Functional and Spatial Big Data Computing Framework for Large-Scale Smart Grid\nYear: 2019\n\nAbstract: With the deployment of monitoring devices, the smart grid is collecting large amounts of energy-related data at an unprecedented speed. The smart grid has become data-driven, which necessitates extracting meaningful data from a large dataset. The traditional approach of data extraction improves the computing efficiency in temporal dimension, but it is made for only one task in the smart grid. Moreover, the existing solutions neglect the geographical distribution of computing capacity in a large-scale smart grid. The future large-scale smart grid will run over the internet of energy where the dataset will be sent to a specific destination along power routers hop-by-hop. Consequently, we design a novel temporal, functional and spatial big data computing framework for large-scale smart grid. In functional dimension, we divide every dataset into sub-groups, each of which has data items shared by different tasks. In spatial dimension, we determine which location the power router should be placed to harvest computing resources used for extracting the sub-group of data items. Our method achieves a promising computing efficiency approaching to the optimal solution with 95% convergence ratio, and it saves the in-path bandwidth with 81% improvement ratio over benchmarks.","Title: Exploring time factors in measuring the scientific impact of scholars.\nYear: 2017\n\nAbstract: Taking advantage of the easy access to the rich and massive scholarly data, more and more researchers are focusing on the studies of analyzing and utilizing the scholarly big data. Among them, evaluating the scientific impact of scholars has significant importance. Measuring the scientific impact of scholars can not only provide basis for the applications of academic foundations and awards, but also shed light on the research directions for scholars. Currently, citation based methods and network based metrics are the most commonly used ways to evaluate the scientific impact. However, these approaches ignore several important facts, i.e. the dynamics of citations and the initial qualities of different articles. To alleviate the shortcomings of them, we propose a Time-aware Ranking algorithm (TRank) to evaluate the impact of scholars. Due to scholars' sustainable supreme concerns of academic innovations, the TRank algorithm gives more credits to the newly published scholarly papers as well as their references according to the representative time functions. Our method also combines the merits of random walk algorithms and heterogeneous network topology, i.e. the mutual influences among different scholarly entities in heterogeneous academic networks. To validate the suitable time function for TRank algorithm and explore its performance, we construct the experiments on two real datasets: (1) Digitial Bibliography and Library Project, and (2) American Physical Society. The experimental results demonstrate that our algorithm outperforms other methods in selecting outstanding scholars and the evaluation results on the overall impact of scholars.","Title: Social acquaintance based routing in Vehicular Social Networks.\nYear: 2019\n\nAbstract: The concept of Internet of Things (IoT) provides us the opportunity to interconnect different objects with the communication and processing capabilities for a diverse range of applications. Recently, Vehicular Social Networks (VSNs) have been introduced through the combination of relevant concepts from two primary disciplines, i.e., social networks and Vehicular Ad hoc Networks (VANETs). Inspired from the social acquaintance in our daily life, we present a Social Acquaintance based Routing Protocol (SARP) for VSNs, which collectively consider three social feature metrics to make a forwarding decision. Proposed protocol aims to reduce End-to-End delay and improve packet delivery ratio in VSNs. Additionally, SARP overcomes the shortcoming of topology based routing and optimum local situation of geographically based routing protocols by considering the global and local community acquaintance of nodes. We performed extensive simulations under constant node density with different mobility speed and constant speed with varying node density to study the effect of node mobility speed and density on end-to-end delay and packet delivery ratio. The simulation results show that SARP outperforms GPSR by 22% and 26% in terms of end-to-end delay and packet delivery ratio respectively. Also, SARP outperforms AOVD in terms of end-to-end delay.","Title: Rising Star Forecasting Based on Social Network Analysis.\nYear: 2017\n\nAbstract: With the development of cyber-physical-social networks, researches on evaluating social influence have drawn increasing interests. Social influence indicates the importance of people in social networks. As a typical type of social networks, how to evaluate scholar influence in the academic social network has been a practical issue for research institutions. In this paper, we aim at evaluating the latent influence of scholars to find academic rising stars, which refer to scholars that may have few papers and little impact currently, but he or she will become influential scholars in the future. Most of the current works focus on the assessment of rising stars. However, there exists a growth period for each scholar. It is unfair for young scholars with limited resources, who will make acquaintance at conferences and recommendations and who will learn from senior scholars. In this paper, we primarily propose StarRank, which is an improved PageRank method to calculate the initial values of rising stars, construct the social network via explicit and implicit links, and apply the neural network to predict scholars' rankings in the future. The experimental results on real data set demonstrate that our method has a better performance than the-state-of-the-art methods on the count of hitting rising stars and the spearman correlation coefficient.","Title: Mobility Dataset Generation for Vehicular Social Networks Based on Floating Car Data.\nYear: 2018\n\nAbstract: Vehicular social networks (VSNs) have attracted the research community due to its diverse applications ranging from safety to entertainment. Social vehicles standing for private cars and floating cars standing for taxis are two important components of VSN. However, the lack of social vehicles data causes some factors are neglected including social aspects and macroscopic features, which blocks res...","Title: Offloading in Internet of Vehicles: A Fog-Enabled Real-Time Traffic Management System.\nYear: 2018\n\nAbstract: Fog computing has been merged with Internet of Vehicle (IoV) systems to provide computational resources for end users, by which low latency can be guaranteed. In this paper, we put forward a feasible solution that enables offloading for real-time traffic management in fog-based IoV systems, aiming to minimize the average response time for events reported by vehicles. First, we construct a distribu...","Title: Service Degradability Supported by Forecasting System in Optical Data Center Networks\nYear: 2019\n\nAbstract: A large-scale distributed scientific computing develops rapidly, making the interconnection of data centers (DCs) become the focus in both academic and industrial communities. Since the fiber transmission has the characteristics of high capacity, low power consumption, and strong reliability, establishing the optical data center network (ODCN)—where DCs are interconnected via optical backbone—is an inevitable trend. In ODCNs, the oversize inter-DC traffic demand suffers from the denial-of-service caused by network overload. Therefore, we propose a provident service degradation (service degradability) framework based on the traffic-demand forecasting system. This forecasting system helps us to precisely know when service degradability becomes necessary, together with the exact location of overload. As a result, service degradability can be adopted at appropriate times and locations. Specifically, we perform bandwidth degradability to overcome the overload of optical backbone, while utilizing computing-resource degradability if there is a DC overload. We simulate and analyze the performance of our prediction system and service degradability algorithm. The simulation results show that the system's prediction result well matches actual traffic demand, and the average absolute relative error is merely 0.0507; and compared with benchmarks, our algorithm has the better performance on maximizing service provider profit via mitigating network congestion.","Title: Integration of Image Feature and Word Relevance: Toward Automatic Image Annotation in Cyber-Physical-Social Systems.\nYear: 2018\n\nAbstract: Image annotation is challenging due to the explosive increase of image data in cyber-physical-social systems. Because of the semantic gap between images and corresponding labels, it has attracted extensive attentions in recent years. However, most existing research neglects the imbalanced distribution of different classes and the internal relevance of image labels. Besides, the weak image labeling affects the annotation performance to some extent. To address these issues, we propose a learning model for image annotation through integrating deep features and label relevance of images. Specifically, we first employ a convolutional neural-network approach to extract the deep features of images and utilize the synthetic minority oversampling technique to deal with the problem of class imbalance. Furthermore, we exploit the correlations, including symbiotic and semantic relationships of labels, to compute the relevance of label sets. Then, we incorporate this relevance into one classifier to reconstruct the complete label sets, and learn the mapping from image features to the reconstructed label sets by the other classifier. In addition, a joint convex loss function is proposed, which combines the two classifiers via co-regularization and compels them to be consistent. We evaluate the proposed method on two benchmark data sets. The experimental results demonstrate that our method outperforms several state-of-the-art solutions.","Title: A Cooperative Partial Computation Offloading Scheme for Mobile Edge Computing Enabled Internet of Things\nYear: 2019\n\nAbstract: With the evolutionary development of latency sensitive applications, delay restriction is becoming an obstacle to run sophisticated applications on mobile devices. Partial computation offloading is promising to enable these applications to execute on mobile user equipments with low latency. However, most of the existing researches focus on either cloud computing or mobile edge computing (MEC) to o...","Title: Joint Resource Allocation for Latency-Sensitive Services over Mobile Edge Computing Networks with Caching\nYear: 2019\n\nAbstract: Mobile edge computing (MEC) has risen as a promising paradigm to provide high quality of experience via relocating the cloud server in close proximity to smart mobile devices (SMDs). In MEC networks, the MEC server with computation capability and storage resource can jointly execute the latency-sensitive offloading tasks and cache the contents requested by SMDs. In order to minimize the total late...","Title: Joint Computation Offloading, Power Allocation, and Channel Assignment for 5G-Enabled Traffic Management Systems\nYear: 2019\n\nAbstract: Due to the ever-increasing requirements of delay-sensitive and mission-critical applications in 5G, mobile edge computing is promising to react and support real-time interactive systems. However, it is still challenging to construct a 5G-enabled traffic management system, owing to the qualification of ultra-low latency and ubiquitous connectivity. Furthermore, the computing resources and storage capacities of edge nodes are limited, thus computation offloading is a fundamental issue for real-time traffic management. This paper puts forward a hybrid computation offloading framework for real-time traffic management in 5G networks. Specially, we consider both nonorthogonal-multiple-access-enabled and vehicle-to-vehicle-based traffic offloading. The investigated problem is formulated as a joint task distribution, subchannel assignment, and power allocation problem, with the objective of maximizing the sum offloading rate. After that, we prove its NP-hardness and decompose it into three subproblems, which can be solved iteratively. Performance evaluations illustrate the effectiveness of our framework.","Title: COMICS: a community property-based triangle motif clustering scheme.\nYear: 2019\n\nAbstract: With the development of science and technology, network scales of various fields have experienced an amazing growth. Networks in the fields of biology, economics and society contain rich hidden information of human beings in the form of connectivity structures. Network analysis is generally modeled as network partition and community detection problems. In this paper, we construct a community property-based triangle motif clustering scheme (COMICS) containing a series of high efficient graph partition procedures and triangle motif-based clustering techniques. In COMICS, four network cutting conditions are considered based on the network connectivity. We first divide the large-scale networks into many dense subgraphs under the cutting conditions before leveraging triangle motifs to refine and specify the partition results. To demonstrate the superiority of our method, we implement the experiments on three large-scale networks, including two co-authorship networks (the American Physical Society (APS) and the Microsoft Academic Graph (MAG)), and two social networks (Facebook and gemsec-Deezer networks). We then use two clustering metrics, compactness and separation, to illustrate the accuracy and runtime of clustering results. A case study is further carried out on APS and MAG data sets, in which we construct a connection between network structures and statistical data with triangle motifs. Results show that our method outperforms others in both runtime and accuracy, and the triangle motif structures can bridge network structures and statistical data in the academic collaboration area.","Title: Privacy-Preserving Content Dissemination for Vehicular Social Networks: Challenges and Solutions\nYear: 2019\n\nAbstract: Vehicular social networks (VSNs), viewed as the integration of traditional vehicular networks and social networks, are promising communication platforms based on the development of intelligent vehicles and deployment of intelligent transportation systems. Passengers can obtain information by searching over Internet or querying vehicles in proximity through intra-vehicle equipment. Hence, the performance of content dissemination in VSNs heavily relies on inter-vehicle communication and human behaviors. However, privacy preservation always conflicts with the usability of individual information in VSNs. The highly dynamic topology and increasing kinds of participants lead to potential threats for communication security and individual privacy. Therefore, the privacy-preserving solutions for content dissemination in VSNs have become extremely challenging, and numerous researches have been conducted recently. Compared with related surveys, this article provides the unique characteristics of privacy-preserving requirements and solutions for content dissemination in VSNs. It focuses on: 1) a comprehensive overview of content dissemination in VSNs; 2) the privacy issues and potential attacks related to content dissemination; and 3) the corresponding solutions based on privacy consideration. First, the characteristics of VSNs, content dissemination and its solutions in VSNs are revealed. Second, the privacy issues for content dissemination in the current VSN architecture are analyzed and classified according to their features. Various privacy-preserving content dissemination schemes, attempting to resist distinct attacks, are also discussed. Finally, the research challenges and open issues are summarized.","Title: Mobile Edge Computing-Enabled 5G Vehicular Networks: Toward the Integration of Communication and Computing\nYear: 2019\n\nAbstract: To meet the requirements of real-time and mission-critical applications in vehicular networks, mobile edge computing (MEC) has become an emerging ecosystem that extends the centralized cloud computing capability to the edge close to terminal devices. Although MEC can bring various benefits, such as high-efficiency use of mobile backhaul networks, coping with the ever-increasing demands of ubiquito...","Title: Local Electricity Storage for Blockchain-based Energy Trading in Industrial Internet of Things\nYear: 2019\n\nAbstract: The peer-to-peer energy trading has been achieved among nodes in industrial Internet of Things. To establish a secure private market, some meaningful works propose the concept of the energy chain, where one block is added in a linear and chronological order once the trading pair of nodes (buyer and seller) has a valid transaction verified by data audit (e.g., a hash value). Since the buyer applies...","Title: Wireless Power Transfer and Energy Harvesting: Current Status and Future Prospects\nYear: 2019\n\nAbstract: The rechargeable battery is the conventional power source for mobile devices. However, limited battery capacity and frequent recharging requires further research to find new ways to deliver power without the hassle of connecting cables. Novel wireless power supply methods, such as energy harvesting and wireless power transfer, are currently receiving considerable attention. In this article, an overview of recent advances in wireless power supply is provided, and several promising applications are presented to show the future trends. In addition, to efficiently schedule the harvested energy, an energy scheduling scheme in the EH-powered D2D relay network is proposed as a case study. To be specific, we first formulate an optimization problem for energy scheduling, and then propose a modified two stage directional water filling algorithm to resolve it.","Title: Smartphone-Based Intelligent Sleep Monitoring.\nYear: 2019\n\nAbstract: The sleeping quality is one of the most important factors to judge people's health status, and has drawn increasing attention of the public recently. However, the quantified results of sleeping quality can generally be achieved in labs with the help of high precision instrument, such as Actigraphy or professional graph like Polysomnography (PSG), and are thus not available for the general public. In this paper, we construct a novel way of sleep-scoring system implanted in the iSmile app. iSmile first collects the sounds recorded by smart phone recorder, then classifies the sound frames with a light weight decision tree algorithm. Based on the number and the average amplitude of sleep-related events, we score the users' sleeping quality in three aspects (respectively cough-score, snore-score and talk-score) using Pittsburgh Sleep Quality Index (PSQI) and Pediatric Sleep Questionnaire (PSQ). During users' sleeping period, iSmile also collects data from the accelerator sensor to predict the users' mood (presented in valence and arousal) and recommend smart alarm sounds to help improve their mood. For the experiment, we involved 5 participants (20 nights in total) and achieved high precision of predicting sleep events (above 89%), with the users' valence and arousal improved by 14.57%. From succinct chart of sleeping score on the App UI, users can see the visualized results of their sleeping quality.","Title: Intelligent Edge Computing in Internet of Vehicles: A Joint Computation Offloading and Caching Solution\nYear: 2021\n\nAbstract: Recently, Internet of Vehicles (IoV) has become one of the most active research fields in both academic and industry, which exploits resources of vehicles and Road Side Units (RSUs) to execute various vehicular applications. Due to the increasing number of vehicles and the asymmetrical distribution of traffic flows, it is essential for the network operator to design intelligent offloading strategies to improve network performance and provide high-quality services for users. However, the lack of global information and the time-variety of IoVs make it challenging to perform effective offloading and caching decisions under long-term energy constraints of RSUs. Since Artificial Intelligence (AI) and machine learning can greatly enhance the intelligence and the performance of IoVs, we push AI inspired computing, caching and communication resources to the proximity of smart vehicles, which jointly enable RSU peer offloading, vehicle-to-RSU offloading and content caching in the IoV framework. A Mix Integer Non-Linear Programming (MINLP) problem is formulated to minimize total network delay, consisting of communication delay, computation delay, network congestion delay and content downloading delay of all users. Then, we develop an online multi-decision making scheme (named OMEN) by leveraging Lyapunov optimization method to solve the formulated problem, and prove that OMEN achieves near-optimal performance. Leveraging strong cognition of AI, we put forward an imitation learning enabled branch-and-bound solution in edge intelligent IoVs to speed up the problem solving process with few training samples. Experimental results based on real-world traffic data demonstrate that our proposed method outperforms other methods from various aspects.","Title: Mobile Edge Computing Enabled 5G Health Monitoring for Internet of Medical Things: A Decentralized Game Theoretic Approach\nYear: 2021\n\nAbstract: The prompt evolution of Internet of Medical Things (IoMT) promotes pervasive in-home health monitoring networks. However, excessive requirements of patients result in insufficient spectrum resources and communication overload. Mobile Edge Computing (MEC) enabled 5G health monitoring is conceived as a favorable paradigm to tackle such an obstacle. In this paper, we construct a cost-efficient in-home health monitoring system for IoMT by dividing it into two sub-networks, i.e., intra-Wireless Body Area Networks (WBANs) and beyond-WBANs. Highlighting the characteristics of IoMT, the cost of patients depends on medical criticality, Age of Information (AoI) and energy consumption. For intra-WBANs, a cooperative game is formulated to allocate the wireless channel resources. While for beyond-WBANs, considering the individual rationality and potential selfishness, a decentralized non-cooperative game is proposed to minimize the system-wide cost in IoMT. We prove that the proposed algorithm can reach a Nash equilibrium. In addition, the upper bound of the algorithm time complexity and the number of patients benefiting from MEC is theoretically derived. Performance evaluations demonstrate the effectiveness of our proposed algorithm with respect to the system-wide cost and the number of patients benefiting from MEC.","Title: Joint User Pairing and Resource Allocation for SWIPT-Enabled Cooperative D2D Communications\nYear: 2021\n\nAbstract: This paper investigates the performance of cooperative device-to-device (C-D2D) communications in a cellular network, where the simultaneous wireless information and power transfer (SWIPT) technology is adopted by D2D transmitters (DTs). In this network, DTs can act as relays that consume a portion of energy harvested by a time switching (TS) strategy to satisfy the quality of service (QoS) requirements of cellular users (CUs) with poor channel conditions, in exchange for spectrum resources of CUs for D2D communications. To achieve the sum-throughput maximization of the network while guaranteeing the QoS requirements of both D2D and cellular links, we formulate a novel optimization problem that jointly determines user pairing between DTs and CI is. time allocation for energy harvesting and information transmission, and power allocation at DTs for relaying information and performing D2D communications. The formulated problem is a non-convex mixed-integer non-linear program (MINLP) problem which is computationally prohibitive. To overcome this issue, a two-step policy-based algorithm is proposed to solve the problem in polynomial time. Simulation results validate the convergence of the proposed algorithm and the effectiveness of the joint user pairing and resource allocation scheme for improving network throughput.","Title: Joint Computing and Caching in 5G-Envisioned Internet of Vehicles: A Deep Reinforcement Learning-Based Traffic Control System\nYear: 2021\n\nAbstract: Recent developments of edge computing and content caching in wireless networks enable the Intelligent Transportation System (ITS) to provide high-quality services for vehicles. However, a variety of vehicular applications and time-varying network status make it challenging for ITS to allocate resources efficiently. Artificial intelligence algorithms, owning the cognitive capability for diverse and time-varying features of Internet of Connected Vehicles (IoCVs), enable an intent-based networking for ITS to tackle the above-mentioned challenges. In this paper, we develop an intent-based traffic control system by investigating Deep Reinforcement Learning (DRL) for 5G-envisioned IoCVs, which can dynamically orchestrate edge computing and content caching to improve the profits of Mobile Network Operator (MNO). By jointly analyzing MNO's revenue and users' quality of experience, we define a profit function to calculate the MNO's profits. After that, we formulate a joint optimization problem to maximize MNO's profits, and develop an intelligent traffic control scheme by investigating DRL, which can improve system profits of the MNO and allocate network resources effectively. Experimental results based on real traffic data demonstrate our designed system is efficient and well-performed.","Title: Blockchain-Enabled Intelligent Transportation Systems: A Distributed Crowdsensing Framework\nYear: 2022\n\nAbstract: Intelligent Transportation System (ITS) is critical to cope with traffic events, e.g., traffic jams and accidents, and provide services for personal traveling. However, existing researches have not jointly considered the user data safety, utility and system latency comprehensively, to the best of our knowledge. Since both safe and efficient transmissions are significant for ITS, we construct a blockchain-enabled crowdsensing framework for distributed traffic management. First, we illustrate the system model and formulate a multi-objective optimization problem. Due to its complexity, we decompose it into two subproblems, and propose the corresponding schemes, i.e., a Deep Reinforcement Learning (DRL)-based algorithm and a DIstributed Alternating Direction mEthod of Multipliers (DIADEM) algorithm. Extensive experiments are carried out to evaluate the performance of our solutions, and experimental results demonstrate that the DRL-based algorithm can legitimately select active miners and transactions to make a satisfied trade-off between the blockchain safety and latency, and the DIADEM algorithm can effectively select task computation modes for vehicles in a distributed way to maximize their social welfare.","Title: Internet of UAVs Based Remote Health Monitoring: An Online eHealth System\nYear: 2021\n\nAbstract: The recent COVID-19 pandemic has brought significant challenges to the traditional healthcare industry. A novel eHealth system is required to cope with infectious and chronic diseases. This article proposes an online eHealth system to monitor patients and provides edge computing services based on the Internet of Unmanned Aerial Vehicles (UAVs). In order to minimize the health monitoring latency an...","Title: Edge Learning for Internet of Medical Things and Its COVID-19 Applications: A Distributed 3C Framework\nYear: 2021\n\nAbstract: With the global outbreak of COVID-19, the Internet of Medical Things (IoMT), as an extension of the Internet of Things (IoT), has received increasing attention due to its ability to remotely monitor the main symptoms. In addition, based on widely collected IoMT data, the spread and even the origin of a pandemic can be traced effectively. However, spectrum resources become scarce with the increasin...","Title: 5G-Enabled UAV-to-Community Offloading: Joint Trajectory Design and Task Scheduling\nYear: 2021\n\nAbstract: Due to line-of-sight communication links and distributed deployment, Unmanned Aerial Vehicles (UAVs) have attracted substantial interest in agile Mobile Edge Computing (MEC) service provision. In this paper, by clustering multiple users into independent communities based on their geographic locations, we design a 5G-enabled UAV-to-community offloading system. A system throughput maximization probl...","Title: Privacy-Preserved Electronic Medical Record Exchanging and Sharing: A Blockchain-Based Smart Healthcare System\nYear: 2022\n\nAbstract: The digitization of Electronic Medical Record (EMR) provides potential access to a wealth of medical information, but also presents new challenges in privacy-preserved EMR exchanging and sharing. In this paper, we propose a blockchain-based smart healthcare system with fine-grained privacy protection for reliable data exchanging and sharing among different users. We design a blockchain-enabled dyn...","Title: Distributed Task Scheduling for Wireless Powered Mobile Edge Computing: A Federated-Learning-Enabled Framework\nYear: 2021\n\nAbstract: Sixth generation (6G) wireless communication networks are expected to provide ultra-low latency and energy-efficient services for global users. The paradigm of wireless powered mobile edge computing (WP-MEC) provides a feasible framework to real-ize the above purposes by leveraging the advantage of both wireless power transfer and MEC. Howev-er, massive network traffic and control information over...","Title: Online Learning for Distributed Computation Offloading in Wireless Powered Mobile Edge Computing Networks\nYear: 2022\n\nAbstract: A novel paradigm named Wireless Powered Mobile Edge Computing (WP-MEC) emerges recently, which integrates Mobile Edge Computing (MEC) and Wireless Power Transfer (WPT) technologies. It enables mobile clients to both extend their computing capacities by task offloading, and charge from edge servers via energy transmission. Existing studies generally focus on the centralized design of task scheduling and energy charging in WP-MEC networks. To meet the decentralization requirement of the near-coming 6G network, we propose an online learning algorithm for computation offloading in WP-MEC networks with a distributed execution manner. Specifically, we first define the delay minimization problem by considering task deadline and energy constraints. Then, we transform it into a primal-dual optimization problem based on the Bellman equation. After that, we design a novel neural model that learns both offloading and time division decisions in each time slot to solve the formulated optimization problem. To train and execute the designed algorithm distributivity, we form multiple learning models decentralized on edge servers and they work coordinately to achieve parameter synchronization. At last, both theoretical and performance analyses show that the designed algorithm has significant advantages in comparison with other representative schemes.","Title: Blockchain-Enabled Electrical Fault Inspection and Secure Transmission in 5G Smart Grids\nYear: 2022\n\nAbstract: The maturity of the 5th-Generation (5G) communication technology promotes a new round of industrial revolution and supports the high-quality development of economic society. However, owing to the scarce communication resources, costly labor and complex geographic environment, inspecting and maintaining electrical faults accurately and timely in a remote grid is rather challenging. To solve this problem, we comprehensively consider secure and efficient signal transmissions to construct an automatic grid fault inspection system and formulate a multi-objective optimization problem. Due to its complexity, we decompose it into two sub-problems, propose a \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">b</u>\nlockchain-\n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">e</u>\nnabled \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">s</u>\necure \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">t</u>\nransmission scheme (BEST) and an \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</u>\nmproved \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">m</u>\narket \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">m</u>\natching (IMM) algorithm, correspondingly. Considering the latency magnitude difference between blockchain verification and intra-domain transmission, the BEST scheme integrates \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">d</u>\neep \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">r</u>\neinforcement learning-based \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</u>\nmproved \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">p</u>\nroximal policy optimization training algorithm (DRIP) and \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">A</u>\n*-based \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">b</u>\ni-\n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">o</u>\nbjective multi-destination \n<underline xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">o</u>\nptimization algorithm (ABOO) to achieve the intra-domain secure transmission. Based on the real city topology and the YouTube video service data statistics, our algorithms can optimize the network performance while guaranteeing the security of signal transmissions.","Title: Intelligent Fingerprint-Based Localization Scheme Using CSI Images for Internet of Things\nYear: 2022\n\nAbstract: Fingerprint-based indoor localization methods have become an important technology because of their wide availability, low hardware costs, and the rapidly growing demand for location-based services. However, it is low precision of positioning and time-consuming for retraining the model when the fingerprint database has changed with new input samples. In this paper, we propose a novel intelligence localization scheme utilizing incremental learning without retraining models based on channel state information (CSI), namely ILCL. CSI phase data are extracted through a modified device driver, and we convert them into CSI images, which are the input to a convolutional neural network for training the weights in the offline stage. The estimated location is obtained by a probabilistic method based on a broad learning system (BLS) that can continue to train rapidly on new input data in the online stage. The ILCL architecture can be characterized as “deep” and “broad” and can further extract features. Experimental results confirm the superiority of ILCL compared with five existing algorithms in two real-world indoor environments with a total area is over 200 \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">${m}^{2}$</tex-math></inline-formula>\n.","Title: Blockchain-Enabled Privacy-Preserving Access Control for Data Publishing and Sharing in the Internet of Medical Things\nYear: 2022\n\nAbstract: Recently, the rapid developments in the Internet of Medical Things (IoMT) enable smart devices to generate and transmit massive personal electronic medical records (EMRs). However, there are many sensitive attributes in an EMR, which could be accessed by external or internal unauthorized users for malicious purposes. In this article, we present a triple subject purpose-based access control (TS-PBAC) model, which is compatible with a blockchain-enabled reliable transaction network, and design an individual-centric security and privacy-preserving mechanism for access control with different purposes and roles in IoMT scenarios. Specifically, we design hierarchical purpose tree (HPT) and related policies to guarantee the legality of an external user with different purposes. To improve the privacy for sensitive attributes against an internal attacker, we design a local differential privacy (LDP)-based policy and role-based access control scheme in an edge computing paradigm to grant fine-granularity rights for authorized users. In addition, we introduce mutual evaluation metrics to evaluate data quality from a patient-and-medical-service level in an open anonymous network, only using logs kept in the blockchain. We test our approach by real-world EMRs with 100000 patients. The experimental results show that the proposed privacy-preserving scheme can better protect patient’s privacy than traditional access control policies in IoMT environments, and can make reliable and stable access control decisions between data publishers and data requesters with different purposes."],"string":"[\n \"Title: Markov-based vertical handoff decision algorithms in heterogeneous wireless networks\\nYear: 2014\\n\\nAbstract: In this paper, we propose a received signal strength (RSS)-based single-attribute handoff decision algorithm at first, and investigate handoff decision model based on connection lifetime, which can keep mobile terminals (MTs) staying long enough in the preferred network. Since the preferred quality of service (QoS) parameters may be distinct among different MTs, we then formulate the vertical handoff decision problem as a Markov decision process, with the objectives of maximizing the expected total reward and minimizing average number of handoffs. A reward function is constructed to assess the QoS during each connection, and the G1 and entropy methods are applied in an iterative way, by which we can work out a stationary deterministic handoff decision policy. Numerical results demonstrate the superiority of our proposed schemes compared with other existing algorithms.\",\n \"Title: Communication Networks Survivable routing algorithm with mixed shared protection in fault-tolerant GMPLS multi-layered optical networks\\nYear: 2010\\n\\nAbstract: In this paper, we studied survivability in general multi-protocol label switching (GMPLS) multi-layered optical networks and proposed a novel mixed shared protection algorithm (MSPA) based on the integrated layered graph (ILG) to tolerate single-fibre link failure. The ILG is composed of one virtual topology layer (VTL), corresponding to IP/MPLS layer; multiple wavelength-plane layers (WPLs), corresponding to the wavelength-division multiplexing (WDM) optical layer; and some virtual links that connect the VTL to each WPL in order to solve the problem on routing, wavelength assignment and low-speed traffic grooming. For every connection request, the MSPA first computes a single-hop or multi-hop label switching path (LSP) pair, involving a working LSP and a physical link-disjoint backup LSP in the VTL. If the LSP pair is not found in the VTL, the MSPA computes the new LSP pair in the WPL. Conversely, if the new LSP pair is not detected in the WPL, the MSPA computes the hybrid multi-hop LSP pair in the ILG. In the MSPA, if the two working LSPs are in physical link-disjoint, their corresponding backup LSPs can share the backup bandwidth. In addition, the working LSPs and the backup LSPs can also share the same mixed of wavelength, in which the different bandwidths can be assigned to different working and backup LSPs. Simulation results show that, compared to previous algorithm, the MSPA can obtain a better bandwidth utilisation ratio (BUR) with a lower blocking probability. Copyright (C) 2010 John Wiley & Sons, Ltd.\",\n \"Title: Joint scheduling and routing algorithm with load balancing in wireless mesh network\\nYear: 2012\\n\\nAbstract: Wireless mesh network (WMN) is a promising solution for last mile broadband internet access. Mesh nodes or mesh routers are connected via wireless links to form a multi-hop backbone infrastructure and improving throughput is the primary goal. While previous works mainly focused on either link level protocol design or complex mathematical model, in this paper, we investigate the performance gains from jointly optimizing scheduling and routing in a multi-radio, multi-channel and multi-hop wireless mesh network. Then, two optimization objectives are addressed by considering wireless media contention and spatial multiplexing. The first objective is to maximize throughput by exploiting spatial reuse while the second one is to ensure fairness among different links. We design a cross-layer algorithm by considering both MAC layer and network layer. Simulation results show that our joint optimization algorithm can significantly increase throughput as well as fairness.\",\n \"Title: Joint power control and spectrum access in cognitive radio networks.\\nYear: 2014\\n\\nAbstract: Cognitive Radio (CR) is proposed to overcome the problem of spectrum underutilization and congestion caused by the increasing demand of wireless services and applications. It is still a challenge to improve the spectrum efficiency of the secondary network for Secondary (unlicensed) Users (SUs) and avoid imposing interference to the Primary (licensed) Users (PUs). In this paper, we propose a joint power control and spectrum access scheme for the CR network. By addressing the power allocation problem and exploiting a Dynamic Spectrum Access (DSA) scheme (which is based on the power allocation and also aims at improving the secondary network throughput) from a cooperative-game perspective, our joint scheme can improve the throughput of the secondary network and guarantee the SUs׳ fairness, without imposing overlarge interference to the PUs. Numerical results reflect that, compared with previous studies, our joint power control and spectrum access scheme presents advantages in comprehensive performance (e.g., spectrum efficiency, fairness and throughput). Beyond a theoretical framework, we solve the optimization problem with the Differential Evolution (DE) algorithm which is more feasible to be implemented in practice.\",\n \"Title: Subcarrier allocation in multi-hop orthogonal frequency division multiple access wireless networks\\nYear: 2014\\n\\nAbstract: Orthogonal frequency division multiplexing (OFDM) has been widely considered as a key technique for next generation mobile communication systems. Meanwhile, relaying technologies can improve users' quality of service, increase network capacity and enlarge cellular coverage at a low cost. In this paper, we focus on subcarrier allocation and utilization in multi-hop OFDM access (OFDMA) wireless networks, and propose two efficient subcarrier allocation schemes aiming to increase network throughput and subcarrier utilization. The first scheme selects suitable links for data transmission from base stations to terminals at the beginning. Then, interference-free links are included into the same group for network resource reuse. For the purpose of global optimization, we propose a Tabu-based searching algorithm as the second subcarrier allocation scheme. Simulation results demonstrate that our proposed algorithms outperform other schemes in both network throughput and subcarrier utilization.\",\n \"Title: A novel scheduling algorithm for physical-layer network coding under Markov model in wireless multi-hop network\\nYear: 2013\\n\\nAbstract: Physical-layer network coding (PNC) is a promising approach for wireless networks: it allows nodes to transmit simultaneously and encode packets by superposing signals at the physical layer, which can improve throughput. Because of the difficulty in scheduling simultaneous transmissions, we propose an opportunistic scheduling algorithm in the media access control (MAC) layer and analyze the achievable throughput of the Denoise-and-Forward (DF) PNC scheme for both symmetric and asymmetric channel statuses, where random errors may occur for both BPSK and QPSK modulation techniques. Simulation results show that our algorithm cannot only improve throughput but can also adapt to varying channel conditions. It is further revealed that for the same throughput, our algorithm is more power-efficient with an asymmetric channel status than with a symmetric channel status.\",\n \"Title: A channel estimation based opportunistic scheduling scheme in wireless bidirectional networks\\nYear: 2014\\n\\nAbstract: Generally speaking, there are two assumptions in the previous bidirectional networks. The first one is assuming that no direct transmission paths exist between the source and destination nodes due to high shadow fading or large separation. The second one is assuming that either channel parameters are pre-established or perfect global channel state information (CSI) can be obtained by the relay nodes. In this paper, we get rid of these limitations and estimate channel gains for both analog network coding (ANC) and time division broadcasting (TDBC) schemes based on outage probability. As the channel gain of each link varies from time to time in wireless networks, we first estimate the channel gain according to outage probability, then propose an opportunistic scheduling scheme to optimize the sum rate values by maximizing the minimum link transmission rate. Simulation results are presented to demonstrate the effectiveness of our channel estimation scheme, and the performance of our proposed opportunistic scheduling scheme is compared with the round robin scheduling (RRS) scheme for both ANC and TDBC schemes.\",\n \"Title: Link stability estimation based on link connectivity changes in mobile ad-hoc networks\\nYear: 2012\\n\\nAbstract: Link stability issue is significant in many aspects, especially for the route selection process in mobile ad-hoc networks (MANETs). Most previous works focus on the link stability in static environments, with fixed sampling windows which are only suitable for certain network topologies. In this paper, we propose a scheme to estimate the link stability based on link connectivity changes, which can be performed on the network layer, without the need of peripheral devices or low layer data. We adopt a variable sized sampling window and propose a method to estimate the link transition rates. The estimation scheme is not restricted to specific network topologies or mobility models. After that, we propose a routing method which adjusts its operating mode based on the estimated link stability. Simulation results show that the proposed scheme can provide correct estimation in both stationary and non-stationary scenarios, and the presented routing protocol outperforms conventional routing schemes without link stability estimation.\",\n \"Title: Deployment of survivable fiber-wireless access for converged optical and data center networks.\\nYear: 2014\\n\\nAbstract: As a promising solution for the bandwidth bottleneck of Data Center (DC) network, the converged optical and DC networks have gained an increasing popularity due to their advantages in rich bandwidth and high reliability. Although the converged optical and DC networks bring the opportunity for high-speed transmission of DC traffic, they also impose more severe challenge on the survivability design, because the network component failure will cause greater data loss. Some works focus on the survivability of core network for the convergence of optical and DC networks and remain less touched on that of access network. In fact, access network plays an important role in the reliable transmission of the traffic between end-users and DC, which accounts for considerable portion of all DC traffic. However, since the vulnerability to component failure, the traditional Passive Optical Network (PON) may no longer satisfy the higher survivability requirement. As an emerging broadband access technology, Fiber-Wireless (FiWi) may be a preferable candidate for the survivable access of converged optical and DC networks. In FiWi access network, the Wireless Mesh Network (WMN) at front-end can protect the Passive Optical Network (PON) at back-end by wirelessly rerouting. This paper focuses on the deployment of survivable FiWi access network against single distribution fiber failure, which is a typical failure scenario in optical access network. We propose a new protection approach called Wireless Rerouting with Backup Radios (WRBR) for the deployment of survivable FiWi access network. In WRBR, we deal with the optimization of wireless routers placement and backup radios configuration. Both Integer Linear Programming (ILP) and heuristic approach are proposed, aiming to minimize the deployment cost. Simulation results demonstrate the advantage of WRBR in saving deployment cost of FiWi access for converged optical and DC networks over the previous works.\",\n \"Title: CITS 2017 general chairs' message\\nYear: 2017\\n\\nAbstract: Welcome to the 2017 International Conference on Computer, Information and Telecommunication Systems (CITS 2017). This year's conference marks the sixth CITS, which is being held on annual basis.\",\n \"Title: Interference-aware spectrum sensing mechanisms in cognitive radio networks\\nYear: 2015\\n\\nAbstract: Throughput vs. spectrum sensing time under high (left) and moderate (right) usage of spectrum.Display Omitted Study spectrum sensing mechanisms by the optimization of network parameters and strategies.The proposed mechanisms have fewer sensing overhead.SUs can access into the spectrum holes efficiently, and transmit with a low power. This paper focuses on the spectrum sensing mechanisms, which could improve network throughput through the sensing strategy optimization and cooperative spectrum sensing methods. In order to guarantee an integrated and effective research, we take the whole channel scenarios into consideration, i.e., Single Secondary user with Single and Multiple Channels (SSSC and SSMC), Multiple Secondary users with Single and Multiple Channels (MSSC and MSMC). Moreover, according to the specific feature of each scenario, different sensing methods are adopted, i.e., optimal sensing period to maximize network throughput for SSSC, a novel sensing method to minimize searching time for SSMC, partial cooperative spectrum sensing mechanism for MSMC, and setting a spectrum pool in the fusion center to record the channel states for MSMC. Simulation results demonstrate that our methods can improve spectrum efficiency, network throughput and channel utilization, especially when the spectrum is utilized inadequately.\",\n \"Title: A novel adaptive spectrum allocation scheme for multi-channel multi-radio wireless mesh networks\\nYear: 2015\\n\\nAbstract: The rapidly developed wireless services and applications have an increasing demand of spectrum resource, which is actually limited. Therefore, how to allocate spectrum resource effectively for network throughput improvement is an urgent issue. Although the utilization of spectrum can be enhanced by link scheduling for spatial reuse, Network Coding (NC) for broadcast transmission, multicast transmission and multi-channel multi-radio techniques, their interactions cannot be ignored. This is because on one hand, the achieved network performance by NC is strongly dependent on the MAC layer, and greedy NC method may in fact reduce network throughput owing to the reduction of spectrum spatial reuse. On the other hand, channel assignment faces more challenges brought by NC and multicast transmission since the broadcast or multicast links are dominated by the link with the worst channel state. In order to utilize the spectrum resource adaptively while not bringing additional constraints, we present a two-phase solution approach. On the first step, we formulate the NC-aware scheduling scheme to an optimization problem, by which the interference-free links are allocated into the same link set and can be activated in the same time slot and channel. Then, we assign different channels to the link sets according to the radio constraints in a heuristic method, which can further increase the utilization of spectrum resource. Finally, simulation results demonstrate that our proposed method can largely increase the utilization of spectrum resource and improve network throughput.\",\n \"Title: Integration of scheduling and network coding in multi-rate wireless mesh networks: Optimization models and algorithms\\nYear: 2016\\n\\nAbstract: In order to fully utilize spectrum resource in wireless mesh networks (WMNs), we propose a combination of some popular communication techniques, including link scheduling, spatial reuse, power and rate adaptation and network coding (NC), to activate as many transmission links as possible during one scheduling period, so that the total scheduling length can be minimized and network throughput can be maximized. Different from previous studies, we consider the interplay among these techniques and present an optimal NC-aware link scheduling mechanism in multi-rate WMNs, which relies on the enumeration of all possible schedules. Due to the high computational complexity of our proposed model, we utilize a column generation (CG)-based method to resolve the optimization problem and decompose it into a master problem (MP) and a pricing problem (PP). Furthermore, we present a distributed power control algorithm for PP, by which the computational complexity of the CG-based scheme can be largely reduced. Simulation results demonstrate the superiority of our method under various network situations.\",\n \"Title: Design of Dynamic Traffic Grooming Algorithm in Software-Defined Wireless Mesh Networks\\nYear: 2015\\n\\nAbstract: Software-Defined Networking (SDN) separates the network control plane from the packet forwarding plane, and provides the upper applications with an global view of the distributed networks state. By making the network device software programmable, this newly emerging networking paradigm can contribute to change the large and highly complex situation of current networks protocol architecture. SDN enabled Wireless Mesh Networks (WMNs) will apply SDN technology into WMNs. By separating network control logic from data forwarding, automatic control and update functions would be achieved by software-driven control logic, which improves network performance and shortens the cycle of network innovation. Traffic engineering problem involves in the task of mapping network traffic distribution to existing physical topology. It can control network resources utilization and fair traffic allocation, which will optimize the utilization of network resources, and solve the imbalance problem of network resources, so that the network will reach a high degree of reliability, robustness and operability. Therefore, the design of dynamic traffic grooming algorithm in SDN enabled Wireless Mesh Networks is of important theoretical significance and practical value. This article focuses on traffic engineering technology in software defined networking. Aiming at the dynamic routing problem, the SDN controller dynamic traffic grooming algorithm is designed, which takes into account both the path length and link utilization to determine routing establishment, so as to achieve the network load balance and reduce the network congestion. Simulation results demonstrate that our proposed dynamic traffic grooming algorithm performs better in terms of average end-to-end throughput, average end-to-end delay and packet loss probability than traditional scheme.\",\n \"Title: A Dynamic Cooperative Monitor Node Selection Algorithm in Wireless Mesh Networks\\nYear: 2015\\n\\nAbstract: Wireless Mesh Network (WMN) is developed as an emerging key solution for wireless broadband connectivity through a flexible and cost-effective way. However, due to the lack of a physical line of defense, the security in such a network is a big concern. Intrusion Detection System (IDS) is considered as one of the most effective security mechanisms in WMN. Traditionally, IDS is operated on the monitor nodes that cooperatively identify and assess intrusions by analyzing their collected network data. Therefore, most IDS mechanisms need to choose a large number of monitor nodes for good rapidity and accuracy, which increases overhead and degrades network performance. In this paper, we propose a dynamic cooperative monitor node selection scheme based on social network analysis to solve the above issue. In the scheme, we choose the monitor nodes according to their influence in the network, which is evaluated by the relationship among the nodes and the analysis of mutual information. Then, the nodes with similar information are divided into the same monitor area. Simulation results show that the proposed scheme can effectively reduce network cost compared with the traditional node section schemes.\",\n \"Title: A Novel Hybrid Routing Forwarding Algorithm in SDN Enabled Wireless Mesh Networks\\nYear: 2015\\n\\nAbstract: As an essential part of next generation Internet, Wireless Mesh Networks (WMNs) have attracted much research attention due to its potential advantages including low up-front cost, ease of deployment, enhanced capacity and service coverage. However, the inherit features of wireless multi-hop networks have put forward a severe challenge for traffic engineering problem. Conventional traffic engineering techniques either locally manipulate network traffic or adopt unreliable best-effort delivery mechanism. Software Defined Networking (SDN) is a new networking paradigm that separates the network control plane from the packet forwarding plane and provides applications with an abstracted centralized view of the distributed network state. A logically centralized controller that has a global network view is responsible for all the control decisions and it communicates with the network-wide distributed forwarding elements via standardized interfaces. Considering the current price of SDN equipments and deployment cost, this paper proposes an idea that gradually increases the number of SDN forwarding element in the networks. In other words, partly deployment of the SDN forwarding element in the networks can achieve fast forwarding traffic. On this basis, a new traffic engineering algorithms named Hybrid Routing Forwarding Algorithm (HRFA) which is based on SDN forwarding and OSPF (Open Shortest Path First) protocol is designed. This hybrid routing scheme divides the network nodes into conventional nodes and SDN forwarding elements (SDN-FE), and chooses effective forwarding strategies for different network elements, which will improve the overall performance of the networks. In order to verify the performance of the proposed algorithms, a number of simulation experiments are carried out in the NS-2 simulation platform. The results show that compared with the traditional routing forwarding method, HRFA can well increase the normalized throughput, and reduce the delay and packet loss.\",\n \"Title: Hierarchic Topology Management by Decision Model and Smart Agents in Space Information Networks\\nYear: 2015\\n\\nAbstract: Space information network, which is envisioned as a new type of self-organizing networks constituted by information systems of land, sea, air, and space, has attracted tremendous interest recently. In this paper, to improve the data delivery performance and the network scalability of space information networks, a new hierarchic topology management scheme based on decision model and smart agents is proposed. Different from the schemes studied in mobile ad hoc networks and wireless sensor networks, the proposed algorithm in space information networks introduces a decision model based on analytic hierarchy process (AHP) to first select cluster heads, and then forms non-overlapping k-hop clusters. The proposed dynamical self-maintenance mechanisms take not only the node mobility but also the cluster equalization into consideration. Smart mobile agents are used to migrate and duplicate functions of cluster heads in a recruiting way, besides of cluster merger/partition disposal, reaffiliation management and adaptive adjustment of information update period. Simulation experiments are performed to evaluate the performance of the proposed algorithm in terms of network scalability, overhead of clustering and reaffiliation frequency. It is shown from the analytical and simulation results that the proposed hierarchic topology management algorithm significantly improves the performance and the scalability of space information networks.\",\n \"Title: A Trust-Based User Assignment Scheme in Ad Hoc Social Networks\\nYear: 2015\\n\\nAbstract: Although cooperation among individuals plays a key factor in the commercial development of wireless networks, trust is an important factor due to the uncertainty and uncontrollability caused by the self-organizing character of different entities. In this paper, we present a trust-based user assignment scheme by considering node sociality, the reason behind is that effective user assignment should not only build a reliable system basing on the behavior of network individuals, but also encourage selfish nodes to forward packets for one another. At first, a model for trustworthiness management is built up by considering social relationship. Then, user assignment for each transmission is decided by a double auction-based mechanism. Simulation result demonstrates that our scheme is able to obtain better network performance than the existing method in link connectivity and social welfare.\",\n \"Title: PNCOIRank: Evaluating the Impact of Scholarly Articles with Positive and Negative Citations.\\nYear: 2016\\n\\nAbstract: Evaluating the impact of an article is a significant topic and has attracted extensive attention. Citation-based assessment methods currently face a limitation, i.e. the anomalous citations patterns still remain poorly understand. To remedy this drawback, we propose a Positive and Negative Conflict of Interest (COI)-based Rank algorithm, named PNCOIRank, to acquire positive COI, negative COI, positive suspected COI and negative suspected COI relationships. We investigate the citation relationships by the following scholarly factors: citing times, the interval of citing time, collaboration times, the interval of collaboration time, and team of citing authors with the purpose of weakening the COI relationships in citation network. A weighted PageRank is finally constructed and employed, with HITS algorithm to assess the impact of articles. Through experiments on American Physical Society (APS) dataset, we show that PNCOIRank significantly outperforms the existing methods in terms of recommendation intensity.\",\n \"Title: Location-Recommendation-Aware Virtual Network Embedding in Energy-Efficient Optical-Wireless Hybrid Networks Supporting 5G Models.\\nYear: 2016\\n\\nAbstract: Given the possibility of ubiquitous 5G wireless access, location data bridge the gap between the physical world and digital online social networking services and also reflect user preferences and even interdependence among users. Owing to this interdependence, the advertiser can push corresponding products to users according to location recommendations, i.e., advertisement targeting. To achieve this mobile cloud computing service, after moving the computing capacity away from end devices to data centres (DCs), the converged infrastructure integrating optical metro and ubiquitous wireless access technologies is proposed in accordance with the 5G model. To minimize energy consumption, we propose a novel design framework of location-recommendation-aware virtual network embedding. This design framework determines the interdependency among user groups so that we can embed the virtual networks owned by user groups with a high interdependence into the same DC of the substrate optical-wireless hybrid infrastructure. Thus, the adviser can locally push the corresponding products to user groups at a single DC instead of consuming a large amount of energy to build inter-DC paths. The simulation results show that our design framework has greater energy efficiency and more profitable advertisement targeting compared with the benchmark, and the result of our heuristic is very close to the upper bound.\",\n \"Title: Geo-Social Distance-Based Data Dissemination for Socially Aware Networking.\\nYear: 2016\\n\\nAbstract: The Internet of Things (IoT), which could connect everything in the world, is promising for the realization of smart cities. However, vehicles connected in the IoT challenges data collection and transmission. Socially aware networking is an emerging paradigm for high-efficiency data dissemination. Existing protocols take advantage of mobile nodes' social characteristics (e.g., user interest) to improve dissemination performance. However, they have not exploited enough of what relations are valuable between user interests and how these relations can affect the dissemination of social IoTs. This paper takes advantage of interest inclusion and intersection to solve the dissemination problem in a conference scenario. By constructing the structure of the Interest Tree to solely represent the relations of interest inclusion and interest intersection, we integrate vehicles' social factors into their geographical information, and introduce the concept of geo-social distance (GSD) as the basis of the proposed strategy. Simulation results demonstrate the superiority of our presented method by comparing with two other existing protocols in terms of four objective metrics, which include delivery ratio, overhead, hop-count, and average latency.\",\n \"Title: Who are the Rising Stars in Academia?\\nYear: 2016\\n\\nAbstract: This paper proposes a novel method named ScholarRank to evaluate the scientific impact of rising stars. Our proposed ScholarRank integrates the merits of both statistical indicators and influence calculation algorithms in heterogeneous academic networks. The ScholarRank method considers three factors, which are the citation counts of authors, the mutual influence among coauthors and the mutual reinforce process among different entities in heterogeneous academic networks. Through experiments on real datasets, we demonstrate that our ScholarRank can efficiently select more top ranking rising stars than other methods.\",\n \"Title: Collaboration Prediction in Heterogeneous Information Networks\\nYear: 2015\\n\\nAbstract: To reveal the information hiding in the scholarly Big Data, relationship analysis among academic entities has been studied from different perspectives in recent years. In this paper, we focus on the problem of collaboration relationship prediction between authors in heterogeneous information networks, and a new method called MACP, i.e., Meta path and author Attribute based Collaboration Prediction model, is proposed to solve this problem. We use a two-phase collaboration probability learning approach. First, topological features with author attributes are extracted from the network, and then a supervised learning algorithm is employed to find the best weight associated with each feature to determine the collaboration relationship. We present the experiments on a real information network, namely the APS network, which shows that our proposed model can generate more accurate results compared with the method only considering structural features.\",\n \"Title: Social-Oriented Resource Management in Cloud-Based Mobile Networks.\\nYear: 2016\\n\\nAbstract: One of the predominant challenges for cloud-based services is the coordination of resources in the application and network layers to provide adaptive service delivery and an acceptable user experience. This article surveys resource management in cloud-based networks. The authors suggest that consideration of users' social associations can improve link connectivity and service delivery, and that us...\",\n \"Title: A secure routing scheme based on social network analysis in wireless mesh networks.\\nYear: 2016\\n\\nAbstract: As an extension of wireless ad hoc and sensor networks, wireless mesh networks (WMNs) are employed as an emerging key solution for wireless broadband connectivity improvement. Due to the lack of physical security guarantees, WMNs are susceptible to various kinds of attack. In this paper, we focus on node social selfish attack, which decreases network performance significantly. Since this type of attack is not obvious to detect, we propose a security routing scheme based on social network and reputation evaluation to solve this attack issue. First, we present a dynamic reputation model to evaluate a nodeu0027s routing behavior, from which we can identify selfish attacks and selfish nodes. Furthermore, a social characteristic evaluation model is studied to evaluate the social relationship among nodes. Groups are built based on the similarity of node social status and we can get a secure routing based on these social groups of nodes. In addition, in our scheme, nodes are encouraged to enter into multiple groups and friend nodes are recommended to join into groups to reduce the possibility of isolated nodes. Simulation results demonstrate that our scheme is able to reflect node security status, and routings are chosen and adjusted according to security status timely and accurately so that the safety and reliability of routing are improved.\",\n \"Title: A Hybrid Mechanism for Innovation Diffusion in Social Networks.\\nYear: 2016\\n\\nAbstract: Innovation diffusion is the process of adopting novel things, which is deemed as the diffusion of human behaviors. Previous studies mainly posit an unclear distinction with information diffusion. However, there exist critical differences in both social and economic areas. Inspired by this observation, we propose a practical method for innovation diffusion based on the process of behavior diffusion, which integrates threshold model with social imitation strategy. The primary goal of our proposed model is to combine individuals' economic as well as social characteristics to study innovation diffusion. The interplay of these two strategies is studied in the context of a coordination game. According to the simulation results on Erdos-Renyi random networks and small-world networks, we find that the conjunction of these two approaches can greatly improve the efficiency of innovation diffusion. In addition, we further study the impacts of varied initial seeds' selection strategies on the overall performance of innovation diffusion using our proposed model.\",\n \"Title: Toward Efficient 5G Transmission: SER Performance Analysis for Asynchronous Physical-Layer Network Coding.\\nYear: 2016\\n\\nAbstract: People's pursuit of higher quality communication has never ceased, which challenges the layout of 5G networks. Physical-layer network coding (PNC), as a key technology for 5G, supplies a powerful platform through leveraging the broadcast nature of wireless media. However, the symbol error rate (SER) of PNC is not well investigated, which would seriously influence user's quality of experience due to packet loss in wireless environment. In this paper, considering both phase and symbol misalignments, we perform analysis on SER of asynchronous PNC. By assuming part of information is known to the relay, and we derive the lower bound for SER. Afterward, through applying the concept of error vector and eliminating redundant terms, we derive the upper bound for SER. Both the lower and upper bounds are applicable to either multiuser detection-based network coding or belief propagation-based maximum a posteriori decoding. Finally, Monte Carlo simulation verifies our results and demonstrates that the bounds are relatively tight. The analytical results derived in this paper can facilitate future studies of practical and theoretical issues on PNC.\",\n \"Title: Cooperative Mechanism for Energy Transportation and Storage in Internet of Energy\\nYear: 2017\\n\\nAbstract: To improve the energy conversion ability and well utilize renewable resources, J. Rifkin first put forward the concept of Internet of energy IoE). Although a peer-to-peer energy sharing mechanism is achieved through bi-directional energy transportation, the approach to solving cooperative energy transportation and storage still needs improving. Traditionally, the redundant energy will be wasted if it cannot be consumed by power load. In fact, the redundant energy can be stored to supply power loads in the future. For this end, we investigate cooperative energy transportation and storage for IoEs in terms of problem analysis, algorithm design, and platform development. After demonstrating the feasibility condition and proving the NP-hard of our problem, we derive the optimal solution by the reduction from a classic knapsack problem. We also design novel heuristics followed by different energy storage strategies. In addition, based on software-defined networking (SDN), a complementary platform is developed to make an effective decision for cooperative energy transportation and storage using heuristics above. Both simulation and experimental results demonstrate the effectiveness of our solutions.\",\n \"Title: CAIS: A Copy Adjustable Incentive Scheme in Community-Based Socially Aware Networking\\nYear: 2017\\n\\nAbstract: Socially aware networking (SAN) is a new communication paradigm, in which the social characteristics of mobile nodes are exploited to improve the performance of data distribution. In SAN, mobile carriers may exhibit selfish behaviors and refuse to relay messages for others for various reasons, such as limited resources (e.g., buffer, energy, and bandwidth) or social relationships. Several incentiv...\",\n \"Title: Vehicular Social Networks: Enabling Smart Mobility.\\nYear: 2017\\n\\nAbstract: Vehicular transportation is an essential part of modern cities. However, the ever increasing number of road accidents, traffic congestion, and other such issues become obstacles for the realization of smart cities. As the integration of the Internet of Vehicles and social networks, vehicular social networks (VSNs) are promising to solve the above-mentioned problems by enabling smart mobility in modern cities, which are likely to pave the way for sustainable development by promoting transportation efficiency. In this article, the definition of and a brief introduction to VSNs are presented first. Existing supporting communication technologies are then summarized. Furthermore, we introduce an application scenario on trajectory data-analysis-based traffic anomaly detection for VSNs. Finally, several research challenges and open issues are highlighted and discussed.\",\n \"Title: Social-Oriented Adaptive Transmission in Opportunistic Internet of Smartphones.\\nYear: 2017\\n\\nAbstract: Stable and reliable wireless communication is one of the critical demands for smart cities to connect people and devices. Although intelligent terminals can be leveraged to deliver and exchange data through Internet, poor network coverage and expensive network access challenge the deployment of network infrastructure. In this paper, we propose a social-oriented smartphone-based adaptive transmissi...\",\n \"Title: Sustainable Strategy for Recycling Edge Devices in Internet of Everything Networks.\\nYear: 2017\\n\\nAbstract: Internet of Everything (IoE) devices have different operation principles, which weakens the network scalability and data interoperability. Virtualization is an economic way of solving this problem. The data-collected by different vendors' sensors-can share the same computing program encapsulated by the Virtual Machine (VM), thus neglecting the physical-layer difference. To eliminate the extreme cost and long delay of transferring VMs to the remote cloud, the Edge Device (ED) preliminary processes its running VMs. Currently, the recycling of IoE devices become a major dilemma for individuals, since it is not simply a matter of concern for environmental damage or a solution to an environmental problem. Therefore, the sustainable strategy for recycling EDs is an important way to safeguard the network sustainability. To improve the recycling efficiency, most of the EDs should be upgraded simultaneously during one batch by migrating their running VMs to others for the service continuity. We investigate the least upgrade batch for recycling EDs in IoE networks. A two-step algorithm called MSBP (Minimized upgrade batch VM Scheduling and Bandwidth Planning) is designed to minimize the number of upgrade batches. Because migrating VM brings the bandwidth consumption along trajectories, MSBP has two strategies-Shortest Trajectory First (STF) and Least Bandwidth Utilization First (LBUF)-of allocating bandwidth and trajectories. The simulation results show that: 1) MSBP has the optimal recycling efficiency (least number of upgrade batches) for EDs; 2) LBUF more effectively mitigates the phenomenon where VM migration trajectories compete for the common link bandwidth, thus achieving a lower negative impact of path contention level on the recycling efficiency; 3) the battery power is not exhausted for the ED functioned as the sensor head of data transferring, thus prolonging the network lifetime. In summary, our solution well improves the network, social, economic and ecological sustainability.\",\n \"Title: Green Virtual Network Embedding for Collaborative Edge Computing in Environment-Friendly Optical-Wireless Networks.\\nYear: 2017\\n\\nAbstract: To reduce the cost and delay caused by transferring data to the remote cloud, the trend is to design an intelligent Edge Device (ED) for preliminary data processing, i.e., edge computing. Some EDs usually form a group where they wirelessly communicate with each other. Different ED groups are interconnected by optical fiber cables. Through coordinating the use of ED groups, we can perform a collaborative edge computing in a hybrid network where a cost-efficient optical-wireless convergence is achieved by virtualization. In this paper, we use the virtual network to describe one computing-application's requirement for the substrate resource, and we investigate how embed multiple virtual networks onto the common network infrastructure. In our approach, a graph-cutting algorithm is firstly utilized to embed as many virtual networks as possible onto the specified EDs within the same group. However, a single ED group cannot handle all computing applications competing for limited wireless and computing resources. To solve this challenging problem, we transform the virtual networks-impossibly embedded onto the same ED group into new ones processed by ED groups. Simulations results demonstrate the green feature of our solution: 1) the total transmitting power assigned for EDs is effectively reduced using the graph cutting algorithm provided that all of computing applications can be solved by a single ED group; 2) our method accepts more virtual networks with the improvement ratio of 77%, through the coordination of ED groups. In addition, there is a good match between the algorithm result and the optimal number of consumed wavelengths per optical fiber cable.\",\n \"Title: Poster: Emotion-Aware Smart Tips for Healthy and Happy Sleep.\\nYear: 2017\\n\\nAbstract: People spend up to one-third of lives asleep, and healthy sleep habits can make a big difference in their quality of life. But in modern society, many people have unhealthy sleep diaries and suffer from various sleep disorders, which may result in irregular mood fluctuations or even mental health problems such as anxiety and depression. We propose the Emotion-Aware Smart Tips (EAST), a novel approach that could help to inform users about their irregular emotional states with smart tips to improve their sleep qualities. EAST aims at helping users keep healthy sleep schedules and emotional states by providing smart tips through a novel model that combines multivariate regression, random forest, and neural network to quantify the relations between sleep patterns and emotional states. Prototype implementation and initial experiments of EAST in mobile phones have demonstrated its desired functionality and practicality for real-world deployment.\",\n \"Title: Joint Encoding and Grouping Multiple Node Pairs for Physical-Layer Network Coding With Low-Complexity Algorithm.\\nYear: 2017\\n\\nAbstract: How to put fifth-generation (5G) into the commercial service by 2020 is still challenging. Since physical-layer network coding (PNC) does not bring unnecessary redundancy and offers satisfactory end-to-end services, it is promising to provide network services in 5G networks. Existing works on PNC mainly focus on the case that two packets are simultaneously sent by a node pair for information excha...\",\n \"Title: The Role of Positive and Negative Citations in Scientific Evaluation.\\nYear: 2017\\n\\nAbstract: Quantifying the impact of scientific papers objectively is crucial for research output assessment, which subsequently affects institution and country rankings, research funding allocations, academic recruitment, and national/international scientific priorities. While most of the assessment schemes based on publication citations may potentially be manipulated through negative citations, in this paper, we explore the conflict of interest (COI) relationships and discover negative citations and subsequently weaken the associated citation strength. Positive and negative COI- distinguished objective rank algorithm (PANDORA) has been developed, which captures the positive and negative COI, together with the positive and negative suspected COI relationships. In order to alleviate the influence caused by negative COI relationship, collaboration times, collaboration time span, citation times, and citation time span are employed to determine the citing strength; while for positive COI relationship, we regard it as normal citation relationship. Furthermore, we calculate the impact of scholarly papers by PageRank and HITS algorithms, based on a credit allocation algorithm which is utilized to assess the impact of institutions fairly and objectively. Experiments are conducted on the publication data set from American Physical Society data set, and the results demonstrate that our method significantly outperforms the current solutions in recommendation intensity of list R at top-K and Spearman's rank correlation coefficient at top-K.\",\n \"Title: An Overview On Evaluating And Predicting Scholarly Article Impact\\nYear: 2017\\n\\nAbstract: Scholarly article impact reflects the significance of academic output recognised by academic peers, and it often plays a crucial role in assessing the scientific achievements of researchers, teams, institutions and countries. It is also used for addressing various needs in the academic and scientific arena, such as recruitment decisions, promotions, and funding allocations. This article provides a comprehensive review of recent progresses related to article impact assessment and prediction. The review starts by sharing some insight into the article impact research and outlines current research status. Some core methods and recent progress are presented to outline how article impact metrics and prediction have evolved to consider integrating multiple networks. Key techniques, including statistical analysis, machine learning, data mining and network science, are discussed. In particular, we highlight important applications of each technique in article impact research. Subsequently, we discuss the open issues and challenges of article impact research. At the same time, this review points out some important research directions, including article impact evaluation by considering Conflict of Interest, time and location information, various distributions of scholarly entities, and rising stars.\",\n \"Title: A Hierarchical Routing Algorithm for Satellite Networks Considering FSO Communication\\nYear: 2017\\n\\nAbstract: Insufficient ground stations promote the emergence of inter-satellite links (ISLs). Nowadays, adopting free space optical (FSO) ISLs has been a new trend for data communications. However, FSO ISLs across the atmosphere may perform worse in adverse weather such as fog or snow. In addition, using ordinary flat routing causes an excessive processing overhead, and diverse quality of experiences (QoEs) cannot be well satisfied. To solve these problems, we propose a Hierarchical Routing protocol for low/medium earth orbit (LEO/MEO) Satellite RF( radio frequency)/FSO Communication Networks (HR-SFCN). The entire network is divided into several LEO-satellite clusters, and each cluster treats the MEO satellite as the manager. To satisfy diverse QoE requirements, we propose the optimization algorithm for data interactions within the cluster. To reduce the processing overhead, we utilize MEO satellites as relay nodes for inter-cluster communications. To guarantee the link availability, we also perform adaptive RF/FSO link switching according to weather conditions. Given a STK(satellite tool kit)-based satellite communication network model, simulation results demonstrate that our HR-SFCN achieves a good trade-off among packet loss rate, path cost and end-to-end delay. Our RF/FSO hybrid system also increases the link availability up to 99.999%.\",\n \"Title: A cloud-supported cps approach to control decision of process manufacturing: 3D ONoC\\nYear: 2017\\n\\nAbstract: The Cyber-Physical System (CPS) concept is now attracting attention in systems engineering, and it is being applied to a fully automated factory control in processes such as semiconductor fabrication. In this paper, we propose a novel control decision structure for process manufacturing, designated as the 3D Optical Network-on-Chip (ONoC) multi-core system, based on the cloud-supported CPS concept. We first construct a task graph - which includes interconnected Virtual Machines (VMs)-to represent the interaction between industrial-physical processes and cyber states. Given the task graph, the control decision process becomes into the problem of the on-chip VM placement. We then design a highly reliable on-chip VM placement scheduling to find the optimal control strategy while guaranteeing the reliability of the 3D ONoC structure. The simulation results demonstrate that our scheme achieves a higher reliability of the 3D ONoC structure when we make the control decision for process manufacturing.\",\n \"Title: An Improved Apriori-Based Algorithm For Friends Recommendation In Microblog\\nYear: 2018\\n\\nAbstract: With the rapid development of Internet, the world has come into a new era of network interaction. Internet development in China makes various kinds of software available to users, by which relatives, close friends, and partners can achieve real-time interactions. It is acknowledged that the recommended issues and persons are the most important parts for user experience. This study concentrates on how to provide a recommendation for users with a common interest in Microblog. We first illustrate some recommended algorithms based on data mining, and the implementation process of friend-recommended system is then stated. After that, by integrating the characteristics of the user information, the forwarding and comments on information to associated users, we present an improved Apriori-based algorithm to rank the recommended information with confidence interval. Simulation results demonstrate the superiority and efficiency of our method.\",\n \"Title: Team Recognition in Big Scholarly Data: Exploring Collaboration Intensity.\\nYear: 2017\\n\\nAbstract: The scale of scholarly data has been expanded due to the fact that scientific productions are increasing rapidly and new scholars affiliate academia incessantly. Scholars are shifting their research patterns from individual research to academic teamwork due to the complexity of scientific issues. In order to achieve higher reputations and better performance, academic teams with leaders are constructed to speed up knowledge sharing and problem solving. It is significant to explore team-based issues with the increasing interests of information exploration in big scholarly data. However, existing academic team definitions are commonly not quantitative, which makes it difficult to identify real academic teams. In this work, we propose a collaboration relationship evaluation index called Collaboration Intensity Index (CII), which is a two-way and quantitative index to evaluate collaboration intensity between two scholars in the network. Then, we construct a new type of co-author network with edges weighted by CII, which differs from the original co-author networks. This network reflects the newly scientific research patterns inside or outside academic teams. Furthermore, we propose TRAC (Team Recognition Algorithm based on CII) to identify academic teams from large co-author networks. Finally, we use DBLP data set, which contains 1,250,440 scholars and 1,575,949 published papers, to identify teams by TRAC. Comparing with fast unfolding algorithm and real team data, the effectiveness of our method can be demonstrated.\",\n \"Title: Green Survivable Collaborative Edge Computing in Smart Cities.\\nYear: 2018\\n\\nAbstract: As an integrated environment deployed with wired and wireless infrastructures, the smart city heavily relies on the wireless-optical broadband access network. The information flows captured by indoor devices are sent to optical network units through front-end wireless mesh sensor networks (WMNs) and, finally, reach the optical line terminal for industrial/commercial decision making via the passive...\",\n \"Title: A Collaborative Filtering Recommendation-Based Scheme for WLANs With Differentiated Access Service.\\nYear: 2018\\n\\nAbstract: As the deployment of WLANs becomes extensive, users commonly have to select one access point (AP) for association among multiple available APs. However, the existing AP selection policies are not sufficient enough due to their drawbacks (e.g., imbalanced load and time consuming for association). In this paper, we present a collaborative filtering (CF) recommendation-based AP selection strategy in ...\",\n \"Title: Vehicular Social Networks: A survey.\\nYear: 2018\\n\\nAbstract: A Vehicular Social Network (VSN) is an emerging field of communication where relevant concepts are being borrowed from two different disciplines, i.e., vehicular ad-hoc networks (VANETs) and mobile social networks (MSNs). This emerging paradigm presents new research fields for content sharing, data dissemination, and delivery services. Based on social network analysis (SNA) applications and methodologies, interdependencies of network entities can be exploited in VSNs for prospective applications. VSNs involve social interactions of commuters having similar objectives, interests, or mobility patterns in the virtual community of vehicles, passengers, and drivers on the roads. In this paper, considering social networking in a vehicular environment, we investigate the prospective applications of VSNs and communication architecture. VSNs benefit from the social behaviors and mobility of nodes to develop novel recommendation systems and route planning. We present a state-of-the-art literature review on socially-aware applications of VSNs, data dissemination, and mobility modeling. Further, we give an overview of different recommendation systems and path planning protocols based on crowdsourcing and cloud-computing with future research directions.\",\n \"Title: A Social-Aware Group Formation Framework for Information Diffusion in Narrowband Internet of Things.\\nYear: 2018\\n\\nAbstract: Due to the heterogeneous and resource-constrained characters of Internet of Things (IoT), how to guarantee ubiquitous network connectivity is challenging. Although LTE cellular technology is the most promising solution to provide network connectivity in IoTs, information diffusion by cellular network not only occupies its saturating bandwidth, but also costs additional fees. Recently, NarrowBand-I...\",\n \"Title: SDN-Enabled Social-Aware Clustering in 5G-VANET Systems.\\nYear: 2018\\n\\nAbstract: Nowadays, vehicular applications for traffic safety, traffic efficiency, and entertainment have put forward higher requirements to vehicular communication systems. The fifth-generation (5G) cellular networks are potential to provide high-capacity low-latency communications for vehicles in highly mobile environments. In addition, the IEEE 802.11p-based dedicated short-range communication technology is proposed to form vehicular ad hoc networks (VANETs). Integrating cluster-based VANETs with 5G cellular networks is beneficial for saving scarce spectrum resources, preventing network congestion, and reducing packet loss. However, it is a challenging problem to find an effective clustering algorithm that has high stability adapting to dynamic VANETs. Considering the advantages of software-defined networking (SDN), in this paper, we present an SDN-enabled social-aware clustering algorithm in the 5G-VANET system, which exploits a social pattern (i.e., vehicles' future routes) prediction model in order to enhance the stability of clusters. Each vehicle's movement is modeled as a discrete time-homogeneous semi-Markov model, where the state transition probability and sojourn time probability distribution are inputs and each vehicle's social pattern is output. The predicted social patterns are subsequently used to create clusters so that vehicles in the same cluster tend to share the same routes. Cluster heads are selected based on the metrics of inter vehicle distance, relative speed, and vehicle attributes. We evaluate our algorithm and the results show that it performs better in terms of cluster lifetime and clustering overhead compared with traditional clustering algorithms.\",\n \"Title: A Survey on Human-Centric Communications in Non-Cooperative Wireless Relay Networks.\\nYear: 2018\\n\\nAbstract: The performance of data delivery in wireless relay networks (WRNs), such as delay-tolerant networks and device-to-device communications heavily relies on the cooperation of mobile nodes (i.e., users and their carried devices). However, selfish nodes may refuse to relay data to others or share their resources with them due to various reasons, such as resource limitations or social preferences. Mean...\",\n \"Title: AIRank: Author Impact Ranking through Positions in Collaboration Networks.\\nYear: 2018\\n\\nAbstract: Citation is a universally acknowledged way for scientific impact evaluation. However, due to its easy manipulability, simply relying on citation cannot objectively reflect the actual impact of scholars. Instead of citation, we utilize the academic networks, in virtue of their available and abundant academic information, to evaluate the scientific impact of scholars in this paper. Through the collaboration among scholars in academic networks, we notice an interesting phenomenon that scholars in some special positions can access more kinds of information and connect researchers from different groups to promote the scientific collaborations. However, this important fact is generally ignored by the existing approaches. Motivated by the observations above, we propose the novel method AIRank to evaluate the scientific impact of scholars. Our method not only considers the impact of scholars through the mutual reinforcement process in heterogeneous academic networks, but also integrates the structural holes theory and information entropy theory to depict the benefit that scholars obtain via their positions in the network. The experimental results demonstrate the effectiveness of AIRank in evaluating the impact of scholars more comprehensively and finding more top ranking scholars with interdisciplinary nature.\",\n \"Title: Combinative hypergraph learning in subspace for cross-modal ranking.\\nYear: 2018\\n\\nAbstract: Recent years have witnessed a surge of interests in cross-modal ranking. To bridge the gap between heterogeneous modalities, many projection based methods have been studied to learn common subspace where the correlation across different modalities can be directly measured. However, these methods generally consider pair-wise relationship merely, while ignoring the high-order relationship. In this paper, a combinative hypergraph learning in subspace for cross-modal ranking (CHLS) is proposed to enhance the performance of cross-modal ranking by capturing high-order relationship. We formulate the cross-modal ranking as a hypergraph learning problem in latent subspace where the high-order relationship among ranking instances can be captured. Furthermore, we propose a combinative hypergraph based on fused similarity information to encode both the intra-similarity in each modality and the inter-similarity across different modalities into the compact subspace representation, which can further enhance the performance of cross-modal ranking. Experiments on three representative cross-modal datasets show the effectiveness of the proposed method for cross-modal ranking. Furthermore, the ranking results achieved by the proposed CHLS can recall 80% of the relevant cross-modal instances at a much earlier stage compared against state-of-the-art methods for both cross-modal ranking tasks, i.e. image query text and text query image.\",\n \"Title: Energy-Latency Tradeoff for Energy-Aware Offloading in Mobile Edge Computing Networks.\\nYear: 2018\\n\\nAbstract: Mobile edge computing (MEC) brings computation capacity to the edge of mobile networks in close proximity to smart mobile devices (SMDs) and contributes to energy saving compared with local computing, but resulting in increased network load and transmission latency. To investigate the tradeoff between energy consumption and latency, we present an energy-aware offloading scheme, which jointly optim...\",\n \"Title: A Cooperative Quality-Aware Service Access System for Social Internet of Vehicles.\\nYear: 2018\\n\\nAbstract: Because of the enormous potential to guarantee road safety and improve driving experience, social Internet of Vehicle (SIoV) is becoming a hot research topic in both academic and industrial circles. As the ever-increasing variety, quantity, and intelligence of on-board equipment, along with the evergrowing demand for service quality of automobiles, the way to provide users with a range of security...\",\n \"Title: A Demand-Supply Oriented Taxi Recommendation System for Vehicular Social Networks.\\nYear: 2018\\n\\nAbstract: To realize the construction of intelligent transportation system, data mining based on large-scale taxi traces has become a hot research topic. A crucial direction for analyzing taxi GPS data set is to recommend cruising areas for taxi drivers. Most of the existing researches merely concentrate on how to maximize drivers' profits while overlooking the benefit of passengers. Such imbalance makes the existing solutions do not work well in a real-world environment. In this paper, we construct a recommendation system by jointly considering the profits of both drivers and passengers. Specifically, we first investigate the real-time demand-supply level for taxis and then make an adaptive tradeoff between the utilities of drivers and passengers for different hotspots. At last, the qualified candidates are recommended to drivers based on the analysis results. Simulation results indicate that the constructed recommendation system can achieve a remarkable improvement on the global utility and make equilibrium between the utilities of drivers and passengers, simultaneously.\",\n \"Title: Novel Framework of Risk-Aware Virtual Network Embedding in Optical Data Center Networks.\\nYear: 2018\\n\\nAbstract: The traffic between geographically distributed data centers (DCs) becomes bandwidth hungry. Since the optical interconnection has a high capacity, the optical data center network (ODCN)-where DCs are located at the edge of the optical backbone-emerges. By virtualization, the virtual networks-representing service requirements-are embedded onto the same part of the substrate ODCN. Each virtual netwo...\",\n \"Title: A City-Wide Real-Time Traffic Management System: Enabling Crowdsensing in Social Internet of Vehicles.\\nYear: 2018\\n\\nAbstract: As an emerging platform based on ITS, SIoV is promising for applications of traffic management and road safety in smart cities. However, the endto- end delay is large in store-carry-and-forwardbased vehicular networks, which has become the main obstacle for the implementation of large-scale SIoV. With the extensive applications of mobile devices, crowdsensing is promising to enable realtime conten...\",\n \"Title: Quick Answer for Big Data in Sharing Economy: Innovative Computer Architecture Design Facilitating Optimal Service-Demand Matching.\\nYear: 2018\\n\\nAbstract: In sharing economy, people offer idle social resources to others in a sharing manner. Through community-based online platforms, the people offering services can earn commission while others can enjoy a better life via renting social resources. Consequently, the value-in-use of services is expectedly strengthened within the unit time, although the total amount of social resources remains constant. ...\",\n \"Title: Heterogeneous visual features integration for image recognition optimization in internet of things.\\nYear: 2018\\n\\nAbstract: •A multimodal deep learning approach for image recognition optimization is proposed.•A back propagation optimization algorithm with shared weights is designed.•Results show our scheme has superior performance on image recognition.\",\n \"Title: Robust Caching Control In Crowdsourced Content-Centric Mobile Networking\\nYear: 2018\\n\\nAbstract: As the global mobile data traffic grows dramatically in recent years, mobile services are shifting from connection-centric communications to content-centric communications. Content-Centric Networking is a promising clean-slate paradigm with the features of named data and in-network caching. However, the content caching and sharing among mobile clients is not yet considered in Content-Centric Mobile Networking (CCMN). In this paper, to supply a stable high quality of service for content distribution, we design a novel crowdsourced CCMN framework firstly. The vicinal mobile users collaborate with each other by crowdsourcing their caching resources and radio links. Subsequently, we analyze the performance bound of crowdsourced CCMN in perspective of cached data. Furthermore, to guarantee the stability of service quality against user mobility, we propose a robust caching control scheme. We use Kullback-Leibler divergence to characterize user mobility distribution uncertainty and formulate the caching control problem into a chance-constrained robust optimization. By the evaluation results, we can see that the robust caching control mechanism can provide not only a more stable but also higher cache hit ratio than other strategies.\",\n \"Title: Big Trajectory Data: A Survey of Applications and Services.\\nYear: 2018\\n\\nAbstract: The rapid development of wireless infrastructure and data acquisition technologies contributes to the explosive growth of data, especially trajectory data with rich information. Trajectory data, which records locations of moving objects at certain moments, has long been an important means of studying human behavior and solving traffic problems. In this paper, we mainly introduce the trajectory data from the perspective of applications and services. According to the degree of data structured, we divide the trajectory data into explicit trajectory data and implicit trajectory data, and describe each type in detail. Then, we introduce the applications of trajectory data from travel behavior, travel patterns, and other aspects. Combined with case studies, we provide a description to the services of trajectory data in terms of transportation administration and commercial service. Finally, we focus on challenges in trajectory data, including privacy protection, human mobility causality, and emission reduction.\",\n \"Title: On-Chip Hardware Accelerator for Automated Diagnosis Through Human-Machine Interactions in Healthcare Delivery.\\nYear: 2019\\n\\nAbstract: The automated diagnosis helps us better understand the complex landscape of diseases, leading to more effective, early and reliable medical diagnosis and therapy. The human-machine interactions in healthcare delivery relying on automated cyber-physical systems (ACPSs) play an important role in the automated diagnosis. Currently, the multicore accelerator used for ACPS has utilized the network-on-c...\",\n \"Title: Green and Sustainable Cloud of Things: Enabling Collaborative Edge Computing\\nYear: 2019\\n\\nAbstract: The proliferation of IoTs beside the emergence of various cloud services push the horizon of edge computing. By offering cloud capabilities at the network edge closer to mobile devices, edge computing is a promising paradigm to resolve several vital challenges in IoTs, such as bandwidth saturation, energy constraints, low latency transmission, and data security and privacy. To provide a comprehensive understanding of edge computing supported by the integration of IoTs and cloud computing, that is, CoTs, this article first discusses some distinct research directions in CoTs with respect to edge computing. Given the significance of energy efficiency and sustainability of edge deployment in CoTs, we put forward a green and sustainable virtual network embedding framework for cooperative edge computing in wireless-optical broadband access networks. Specifically, we leverage a reliability function to confirm the number of backup edge devices, and embed virtual networks onto the suitable edge devices in CoTs. Finally, several research challenges and open issues are discussed.\",\n \"Title: A Privacy-Preserving Message Forwarding Framework for Opportunistic Cloud of Things.\\nYear: 2018\\n\\nAbstract: As an emerging communication platform, opportunistic Cloud of Things (CoT) is promising for clients to exchange messages through opportunistic contacts in cloud computing-enabled Internet of Things. Recently, numerous socially aware schemes have been put forward, leveraging users’ social attributes and contact history to predict future contacts with the purpose of improving message forwarding effi...\",\n \"Title: The Impact Of Digital Alarm Sound To Human Emotions: A Case Study\\nYear: 2018\\n\\nAbstract: In many people's daily life, alarm sounds play an important role, which reflects the fast paced life in the modern society. On most occasions, people uses alarm sounds to wake them up in the morning. Improper alarm sounds may make people feel terrible. In this paper, we mainly propose a smart alarm sound recommendation system and construct an application to study how alarm sounds can impact human emotions. The recommendation system is deployed on the cloud, working with smartphones to deliver smart alarm sounds by considering not only sleep patterns, but also context information such as weather. The designed system can recommend smart alarm sounds to users, orchestrate sensing data collected by multiple sensors on smartphones, and collaborate with the cloud to recommend preferable alarm sounds. An application is developed to demonstrate system effectiveness, which consists of the fore-end on Android OS and the back-end on the cloud. Experiments demonstrate that our system can recommend smart alarm sounds to wake participants up in the morning, and the participants give feedback about their emotional states. The results show that the system can improve people's emotion states by about 14.57%, compared to the traditional alarm sound delivery.\",\n \"Title: Optimizing Content Dissemination for Real-Time Traffic Management in Large-Scale Internet of Vehicle Systems\\nYear: 2019\\n\\nAbstract: As an application of “smart transport” for Internet of Things, Internet of Vehicle (IoV) has emerged as a new research field based on vehicular ad hoc networks (VANETs). With the development of smart vehicles and the integration of sensors, applications of traffic management and road safety in large-scale IoV systems have drawn great attentions. By sensing events occurred on roads, vehicles can broadcast messages to inform others about traffic jams or accidents. However, the store-carry-and-forward transmission pattern may cause a large transmission delay, making the implementation of large-scale traffic management difficult. In this paper, we put forward a feasible solution to minimize the response time for traffic management service, by enabling real-time content dissemination based on heterogeneous network access in IoV systems. We first design a crowdsensing-based system model for large-scale IoV systems. Then, a cluster-based optimization framework is investigated to provide timely responses for traffic management. Specifically, we estimate the message transmission delay by stochastic theory, which can provide a guideline for the next-hop relay selection in our delay-sensitive routing scheme. Furthermore, network performances are evaluated based on two city-road maps, and performance metrics, containing average delivery delay, average delivery ratio, average communication cost, and access ratio, demonstrate the superiority of our system. Finally, we conclude our work and discuss the further work.\",\n \"Title: Vehicular Fog Computing: Enabling Real-Time Traffic Management for Smart Cities\\nYear: 2019\\n\\nAbstract: Fog computing extends the facility of cloud computing from the center to edge networks. Although fog computing has the advantages of location awareness and low latency, the rising requirements of ubiquitous connectivity and ultra-low latency challenge real-time traffic management for smart cities. As an integration of fog computing and vehicular networks, vehicular fog computing (VFC) is promising to achieve real-time and location-aware network responses. Since the concept and use case of VFC are in the initial phase, this article first constructs a three-layer VFC model to enable distributed traffic management in order to minimize the response time of citywide events collected and reported by vehicles. Furthermore, the VFC-enabled offloading scheme is formulated as an optimization problem by leveraging moving and parked vehicles as fog nodes. A real-world taxi-trajectory-based performance analysis validates our model. Finally, some research challenges and open issues toward VFC-enabled traffic management are summarized and highlighted.\",\n \"Title: Appropriate Service Degradability for Virtualized Inter-Data-Center Optical Networks.\\nYear: 2018\\n\\nAbstract: Performing virtualization can further improve the infrastructure utilization of Inter-Data-Center Optical Networks (IDCONs). In virtualized IDCONs, a service requestor subscribes one lightpath for transferring the virtual machine to the specific server in the destination DC. However, the infrastructure overload leads to the denial of services. Thus, we design a novel service degradability (well-intentioned service degradation) framework, in order to minimize the number of service requirements declined by overloads, resulting in the maximal utility of the IDCON provider. We mathematically formulate the problem and determine the most appropriate degradation degree based on microeconomic theory. For heuristic algorithms, the availability-aware bandwidth degradability policy is invoked once there is the optical backbone overload; while for the server overload in DCs, the application-specific virtual machine degradability policy is considered. Finally, the simulation results demonstrate the effectiveness of our heuristic algorithms, and the optimal combination of degradation coefficients is achieved by microeconomic theory and LINGO.\",\n \"Title: An Interference Coordination-Based Distributed Resource Allocation Scheme in Heterogeneous Cellular Networks.\\nYear: 2017\\n\\nAbstract: As a result of the significant increase of overlapped coverage areas among base stations (BSs), interference coordination in heterogeneous cellular networks (HetCNets) becomes necessary, since interference would degrade network performance and even cause dropped calls. In addition, various types of BSs coexist in HetCNets, and BSs with low power (such as Pico BSs and Femto BSs) are deployed more arbitrarily than those in macrocell BSs (MBSs) so that the traditional anti-interference technologies are not enough in HetCNets. To reduce the interference between MBSs and low-power BSs within the coverage, a novel distributed resource allocation algorithm is proposed. First, an interference graph is established, by which the corresponding orthogonal resources can be assigned to different BSs, and the users can be classified into center and edge users, respectively. After that, users select appropriate resource blocks according to an improved proportional fair algorithm, and BSs distribute transmission power to different resource blocks to enhance network throughput further. Simulation results demonstrate the effectiveness of our proposed scheme in resource allocation and utilization.\",\n \"Title: Temporal, Functional and Spatial Big Data Computing Framework for Large-Scale Smart Grid\\nYear: 2019\\n\\nAbstract: With the deployment of monitoring devices, the smart grid is collecting large amounts of energy-related data at an unprecedented speed. The smart grid has become data-driven, which necessitates extracting meaningful data from a large dataset. The traditional approach of data extraction improves the computing efficiency in temporal dimension, but it is made for only one task in the smart grid. Moreover, the existing solutions neglect the geographical distribution of computing capacity in a large-scale smart grid. The future large-scale smart grid will run over the internet of energy where the dataset will be sent to a specific destination along power routers hop-by-hop. Consequently, we design a novel temporal, functional and spatial big data computing framework for large-scale smart grid. In functional dimension, we divide every dataset into sub-groups, each of which has data items shared by different tasks. In spatial dimension, we determine which location the power router should be placed to harvest computing resources used for extracting the sub-group of data items. Our method achieves a promising computing efficiency approaching to the optimal solution with 95% convergence ratio, and it saves the in-path bandwidth with 81% improvement ratio over benchmarks.\",\n \"Title: Exploring time factors in measuring the scientific impact of scholars.\\nYear: 2017\\n\\nAbstract: Taking advantage of the easy access to the rich and massive scholarly data, more and more researchers are focusing on the studies of analyzing and utilizing the scholarly big data. Among them, evaluating the scientific impact of scholars has significant importance. Measuring the scientific impact of scholars can not only provide basis for the applications of academic foundations and awards, but also shed light on the research directions for scholars. Currently, citation based methods and network based metrics are the most commonly used ways to evaluate the scientific impact. However, these approaches ignore several important facts, i.e. the dynamics of citations and the initial qualities of different articles. To alleviate the shortcomings of them, we propose a Time-aware Ranking algorithm (TRank) to evaluate the impact of scholars. Due to scholars' sustainable supreme concerns of academic innovations, the TRank algorithm gives more credits to the newly published scholarly papers as well as their references according to the representative time functions. Our method also combines the merits of random walk algorithms and heterogeneous network topology, i.e. the mutual influences among different scholarly entities in heterogeneous academic networks. To validate the suitable time function for TRank algorithm and explore its performance, we construct the experiments on two real datasets: (1) Digitial Bibliography and Library Project, and (2) American Physical Society. The experimental results demonstrate that our algorithm outperforms other methods in selecting outstanding scholars and the evaluation results on the overall impact of scholars.\",\n \"Title: Social acquaintance based routing in Vehicular Social Networks.\\nYear: 2019\\n\\nAbstract: The concept of Internet of Things (IoT) provides us the opportunity to interconnect different objects with the communication and processing capabilities for a diverse range of applications. Recently, Vehicular Social Networks (VSNs) have been introduced through the combination of relevant concepts from two primary disciplines, i.e., social networks and Vehicular Ad hoc Networks (VANETs). Inspired from the social acquaintance in our daily life, we present a Social Acquaintance based Routing Protocol (SARP) for VSNs, which collectively consider three social feature metrics to make a forwarding decision. Proposed protocol aims to reduce End-to-End delay and improve packet delivery ratio in VSNs. Additionally, SARP overcomes the shortcoming of topology based routing and optimum local situation of geographically based routing protocols by considering the global and local community acquaintance of nodes. We performed extensive simulations under constant node density with different mobility speed and constant speed with varying node density to study the effect of node mobility speed and density on end-to-end delay and packet delivery ratio. The simulation results show that SARP outperforms GPSR by 22% and 26% in terms of end-to-end delay and packet delivery ratio respectively. Also, SARP outperforms AOVD in terms of end-to-end delay.\",\n \"Title: Rising Star Forecasting Based on Social Network Analysis.\\nYear: 2017\\n\\nAbstract: With the development of cyber-physical-social networks, researches on evaluating social influence have drawn increasing interests. Social influence indicates the importance of people in social networks. As a typical type of social networks, how to evaluate scholar influence in the academic social network has been a practical issue for research institutions. In this paper, we aim at evaluating the latent influence of scholars to find academic rising stars, which refer to scholars that may have few papers and little impact currently, but he or she will become influential scholars in the future. Most of the current works focus on the assessment of rising stars. However, there exists a growth period for each scholar. It is unfair for young scholars with limited resources, who will make acquaintance at conferences and recommendations and who will learn from senior scholars. In this paper, we primarily propose StarRank, which is an improved PageRank method to calculate the initial values of rising stars, construct the social network via explicit and implicit links, and apply the neural network to predict scholars' rankings in the future. The experimental results on real data set demonstrate that our method has a better performance than the-state-of-the-art methods on the count of hitting rising stars and the spearman correlation coefficient.\",\n \"Title: Mobility Dataset Generation for Vehicular Social Networks Based on Floating Car Data.\\nYear: 2018\\n\\nAbstract: Vehicular social networks (VSNs) have attracted the research community due to its diverse applications ranging from safety to entertainment. Social vehicles standing for private cars and floating cars standing for taxis are two important components of VSN. However, the lack of social vehicles data causes some factors are neglected including social aspects and macroscopic features, which blocks res...\",\n \"Title: Offloading in Internet of Vehicles: A Fog-Enabled Real-Time Traffic Management System.\\nYear: 2018\\n\\nAbstract: Fog computing has been merged with Internet of Vehicle (IoV) systems to provide computational resources for end users, by which low latency can be guaranteed. In this paper, we put forward a feasible solution that enables offloading for real-time traffic management in fog-based IoV systems, aiming to minimize the average response time for events reported by vehicles. First, we construct a distribu...\",\n \"Title: Service Degradability Supported by Forecasting System in Optical Data Center Networks\\nYear: 2019\\n\\nAbstract: A large-scale distributed scientific computing develops rapidly, making the interconnection of data centers (DCs) become the focus in both academic and industrial communities. Since the fiber transmission has the characteristics of high capacity, low power consumption, and strong reliability, establishing the optical data center network (ODCN)—where DCs are interconnected via optical backbone—is an inevitable trend. In ODCNs, the oversize inter-DC traffic demand suffers from the denial-of-service caused by network overload. Therefore, we propose a provident service degradation (service degradability) framework based on the traffic-demand forecasting system. This forecasting system helps us to precisely know when service degradability becomes necessary, together with the exact location of overload. As a result, service degradability can be adopted at appropriate times and locations. Specifically, we perform bandwidth degradability to overcome the overload of optical backbone, while utilizing computing-resource degradability if there is a DC overload. We simulate and analyze the performance of our prediction system and service degradability algorithm. The simulation results show that the system's prediction result well matches actual traffic demand, and the average absolute relative error is merely 0.0507; and compared with benchmarks, our algorithm has the better performance on maximizing service provider profit via mitigating network congestion.\",\n \"Title: Integration of Image Feature and Word Relevance: Toward Automatic Image Annotation in Cyber-Physical-Social Systems.\\nYear: 2018\\n\\nAbstract: Image annotation is challenging due to the explosive increase of image data in cyber-physical-social systems. Because of the semantic gap between images and corresponding labels, it has attracted extensive attentions in recent years. However, most existing research neglects the imbalanced distribution of different classes and the internal relevance of image labels. Besides, the weak image labeling affects the annotation performance to some extent. To address these issues, we propose a learning model for image annotation through integrating deep features and label relevance of images. Specifically, we first employ a convolutional neural-network approach to extract the deep features of images and utilize the synthetic minority oversampling technique to deal with the problem of class imbalance. Furthermore, we exploit the correlations, including symbiotic and semantic relationships of labels, to compute the relevance of label sets. Then, we incorporate this relevance into one classifier to reconstruct the complete label sets, and learn the mapping from image features to the reconstructed label sets by the other classifier. In addition, a joint convex loss function is proposed, which combines the two classifiers via co-regularization and compels them to be consistent. We evaluate the proposed method on two benchmark data sets. The experimental results demonstrate that our method outperforms several state-of-the-art solutions.\",\n \"Title: A Cooperative Partial Computation Offloading Scheme for Mobile Edge Computing Enabled Internet of Things\\nYear: 2019\\n\\nAbstract: With the evolutionary development of latency sensitive applications, delay restriction is becoming an obstacle to run sophisticated applications on mobile devices. Partial computation offloading is promising to enable these applications to execute on mobile user equipments with low latency. However, most of the existing researches focus on either cloud computing or mobile edge computing (MEC) to o...\",\n \"Title: Joint Resource Allocation for Latency-Sensitive Services over Mobile Edge Computing Networks with Caching\\nYear: 2019\\n\\nAbstract: Mobile edge computing (MEC) has risen as a promising paradigm to provide high quality of experience via relocating the cloud server in close proximity to smart mobile devices (SMDs). In MEC networks, the MEC server with computation capability and storage resource can jointly execute the latency-sensitive offloading tasks and cache the contents requested by SMDs. In order to minimize the total late...\",\n \"Title: Joint Computation Offloading, Power Allocation, and Channel Assignment for 5G-Enabled Traffic Management Systems\\nYear: 2019\\n\\nAbstract: Due to the ever-increasing requirements of delay-sensitive and mission-critical applications in 5G, mobile edge computing is promising to react and support real-time interactive systems. However, it is still challenging to construct a 5G-enabled traffic management system, owing to the qualification of ultra-low latency and ubiquitous connectivity. Furthermore, the computing resources and storage capacities of edge nodes are limited, thus computation offloading is a fundamental issue for real-time traffic management. This paper puts forward a hybrid computation offloading framework for real-time traffic management in 5G networks. Specially, we consider both nonorthogonal-multiple-access-enabled and vehicle-to-vehicle-based traffic offloading. The investigated problem is formulated as a joint task distribution, subchannel assignment, and power allocation problem, with the objective of maximizing the sum offloading rate. After that, we prove its NP-hardness and decompose it into three subproblems, which can be solved iteratively. Performance evaluations illustrate the effectiveness of our framework.\",\n \"Title: COMICS: a community property-based triangle motif clustering scheme.\\nYear: 2019\\n\\nAbstract: With the development of science and technology, network scales of various fields have experienced an amazing growth. Networks in the fields of biology, economics and society contain rich hidden information of human beings in the form of connectivity structures. Network analysis is generally modeled as network partition and community detection problems. In this paper, we construct a community property-based triangle motif clustering scheme (COMICS) containing a series of high efficient graph partition procedures and triangle motif-based clustering techniques. In COMICS, four network cutting conditions are considered based on the network connectivity. We first divide the large-scale networks into many dense subgraphs under the cutting conditions before leveraging triangle motifs to refine and specify the partition results. To demonstrate the superiority of our method, we implement the experiments on three large-scale networks, including two co-authorship networks (the American Physical Society (APS) and the Microsoft Academic Graph (MAG)), and two social networks (Facebook and gemsec-Deezer networks). We then use two clustering metrics, compactness and separation, to illustrate the accuracy and runtime of clustering results. A case study is further carried out on APS and MAG data sets, in which we construct a connection between network structures and statistical data with triangle motifs. Results show that our method outperforms others in both runtime and accuracy, and the triangle motif structures can bridge network structures and statistical data in the academic collaboration area.\",\n \"Title: Privacy-Preserving Content Dissemination for Vehicular Social Networks: Challenges and Solutions\\nYear: 2019\\n\\nAbstract: Vehicular social networks (VSNs), viewed as the integration of traditional vehicular networks and social networks, are promising communication platforms based on the development of intelligent vehicles and deployment of intelligent transportation systems. Passengers can obtain information by searching over Internet or querying vehicles in proximity through intra-vehicle equipment. Hence, the performance of content dissemination in VSNs heavily relies on inter-vehicle communication and human behaviors. However, privacy preservation always conflicts with the usability of individual information in VSNs. The highly dynamic topology and increasing kinds of participants lead to potential threats for communication security and individual privacy. Therefore, the privacy-preserving solutions for content dissemination in VSNs have become extremely challenging, and numerous researches have been conducted recently. Compared with related surveys, this article provides the unique characteristics of privacy-preserving requirements and solutions for content dissemination in VSNs. It focuses on: 1) a comprehensive overview of content dissemination in VSNs; 2) the privacy issues and potential attacks related to content dissemination; and 3) the corresponding solutions based on privacy consideration. First, the characteristics of VSNs, content dissemination and its solutions in VSNs are revealed. Second, the privacy issues for content dissemination in the current VSN architecture are analyzed and classified according to their features. Various privacy-preserving content dissemination schemes, attempting to resist distinct attacks, are also discussed. Finally, the research challenges and open issues are summarized.\",\n \"Title: Mobile Edge Computing-Enabled 5G Vehicular Networks: Toward the Integration of Communication and Computing\\nYear: 2019\\n\\nAbstract: To meet the requirements of real-time and mission-critical applications in vehicular networks, mobile edge computing (MEC) has become an emerging ecosystem that extends the centralized cloud computing capability to the edge close to terminal devices. Although MEC can bring various benefits, such as high-efficiency use of mobile backhaul networks, coping with the ever-increasing demands of ubiquito...\",\n \"Title: Local Electricity Storage for Blockchain-based Energy Trading in Industrial Internet of Things\\nYear: 2019\\n\\nAbstract: The peer-to-peer energy trading has been achieved among nodes in industrial Internet of Things. To establish a secure private market, some meaningful works propose the concept of the energy chain, where one block is added in a linear and chronological order once the trading pair of nodes (buyer and seller) has a valid transaction verified by data audit (e.g., a hash value). Since the buyer applies...\",\n \"Title: Wireless Power Transfer and Energy Harvesting: Current Status and Future Prospects\\nYear: 2019\\n\\nAbstract: The rechargeable battery is the conventional power source for mobile devices. However, limited battery capacity and frequent recharging requires further research to find new ways to deliver power without the hassle of connecting cables. Novel wireless power supply methods, such as energy harvesting and wireless power transfer, are currently receiving considerable attention. In this article, an overview of recent advances in wireless power supply is provided, and several promising applications are presented to show the future trends. In addition, to efficiently schedule the harvested energy, an energy scheduling scheme in the EH-powered D2D relay network is proposed as a case study. To be specific, we first formulate an optimization problem for energy scheduling, and then propose a modified two stage directional water filling algorithm to resolve it.\",\n \"Title: Smartphone-Based Intelligent Sleep Monitoring.\\nYear: 2019\\n\\nAbstract: The sleeping quality is one of the most important factors to judge people's health status, and has drawn increasing attention of the public recently. However, the quantified results of sleeping quality can generally be achieved in labs with the help of high precision instrument, such as Actigraphy or professional graph like Polysomnography (PSG), and are thus not available for the general public. In this paper, we construct a novel way of sleep-scoring system implanted in the iSmile app. iSmile first collects the sounds recorded by smart phone recorder, then classifies the sound frames with a light weight decision tree algorithm. Based on the number and the average amplitude of sleep-related events, we score the users' sleeping quality in three aspects (respectively cough-score, snore-score and talk-score) using Pittsburgh Sleep Quality Index (PSQI) and Pediatric Sleep Questionnaire (PSQ). During users' sleeping period, iSmile also collects data from the accelerator sensor to predict the users' mood (presented in valence and arousal) and recommend smart alarm sounds to help improve their mood. For the experiment, we involved 5 participants (20 nights in total) and achieved high precision of predicting sleep events (above 89%), with the users' valence and arousal improved by 14.57%. From succinct chart of sleeping score on the App UI, users can see the visualized results of their sleeping quality.\",\n \"Title: Intelligent Edge Computing in Internet of Vehicles: A Joint Computation Offloading and Caching Solution\\nYear: 2021\\n\\nAbstract: Recently, Internet of Vehicles (IoV) has become one of the most active research fields in both academic and industry, which exploits resources of vehicles and Road Side Units (RSUs) to execute various vehicular applications. Due to the increasing number of vehicles and the asymmetrical distribution of traffic flows, it is essential for the network operator to design intelligent offloading strategies to improve network performance and provide high-quality services for users. However, the lack of global information and the time-variety of IoVs make it challenging to perform effective offloading and caching decisions under long-term energy constraints of RSUs. Since Artificial Intelligence (AI) and machine learning can greatly enhance the intelligence and the performance of IoVs, we push AI inspired computing, caching and communication resources to the proximity of smart vehicles, which jointly enable RSU peer offloading, vehicle-to-RSU offloading and content caching in the IoV framework. A Mix Integer Non-Linear Programming (MINLP) problem is formulated to minimize total network delay, consisting of communication delay, computation delay, network congestion delay and content downloading delay of all users. Then, we develop an online multi-decision making scheme (named OMEN) by leveraging Lyapunov optimization method to solve the formulated problem, and prove that OMEN achieves near-optimal performance. Leveraging strong cognition of AI, we put forward an imitation learning enabled branch-and-bound solution in edge intelligent IoVs to speed up the problem solving process with few training samples. Experimental results based on real-world traffic data demonstrate that our proposed method outperforms other methods from various aspects.\",\n \"Title: Mobile Edge Computing Enabled 5G Health Monitoring for Internet of Medical Things: A Decentralized Game Theoretic Approach\\nYear: 2021\\n\\nAbstract: The prompt evolution of Internet of Medical Things (IoMT) promotes pervasive in-home health monitoring networks. However, excessive requirements of patients result in insufficient spectrum resources and communication overload. Mobile Edge Computing (MEC) enabled 5G health monitoring is conceived as a favorable paradigm to tackle such an obstacle. In this paper, we construct a cost-efficient in-home health monitoring system for IoMT by dividing it into two sub-networks, i.e., intra-Wireless Body Area Networks (WBANs) and beyond-WBANs. Highlighting the characteristics of IoMT, the cost of patients depends on medical criticality, Age of Information (AoI) and energy consumption. For intra-WBANs, a cooperative game is formulated to allocate the wireless channel resources. While for beyond-WBANs, considering the individual rationality and potential selfishness, a decentralized non-cooperative game is proposed to minimize the system-wide cost in IoMT. We prove that the proposed algorithm can reach a Nash equilibrium. In addition, the upper bound of the algorithm time complexity and the number of patients benefiting from MEC is theoretically derived. Performance evaluations demonstrate the effectiveness of our proposed algorithm with respect to the system-wide cost and the number of patients benefiting from MEC.\",\n \"Title: Joint User Pairing and Resource Allocation for SWIPT-Enabled Cooperative D2D Communications\\nYear: 2021\\n\\nAbstract: This paper investigates the performance of cooperative device-to-device (C-D2D) communications in a cellular network, where the simultaneous wireless information and power transfer (SWIPT) technology is adopted by D2D transmitters (DTs). In this network, DTs can act as relays that consume a portion of energy harvested by a time switching (TS) strategy to satisfy the quality of service (QoS) requirements of cellular users (CUs) with poor channel conditions, in exchange for spectrum resources of CUs for D2D communications. To achieve the sum-throughput maximization of the network while guaranteeing the QoS requirements of both D2D and cellular links, we formulate a novel optimization problem that jointly determines user pairing between DTs and CI is. time allocation for energy harvesting and information transmission, and power allocation at DTs for relaying information and performing D2D communications. The formulated problem is a non-convex mixed-integer non-linear program (MINLP) problem which is computationally prohibitive. To overcome this issue, a two-step policy-based algorithm is proposed to solve the problem in polynomial time. Simulation results validate the convergence of the proposed algorithm and the effectiveness of the joint user pairing and resource allocation scheme for improving network throughput.\",\n \"Title: Joint Computing and Caching in 5G-Envisioned Internet of Vehicles: A Deep Reinforcement Learning-Based Traffic Control System\\nYear: 2021\\n\\nAbstract: Recent developments of edge computing and content caching in wireless networks enable the Intelligent Transportation System (ITS) to provide high-quality services for vehicles. However, a variety of vehicular applications and time-varying network status make it challenging for ITS to allocate resources efficiently. Artificial intelligence algorithms, owning the cognitive capability for diverse and time-varying features of Internet of Connected Vehicles (IoCVs), enable an intent-based networking for ITS to tackle the above-mentioned challenges. In this paper, we develop an intent-based traffic control system by investigating Deep Reinforcement Learning (DRL) for 5G-envisioned IoCVs, which can dynamically orchestrate edge computing and content caching to improve the profits of Mobile Network Operator (MNO). By jointly analyzing MNO's revenue and users' quality of experience, we define a profit function to calculate the MNO's profits. After that, we formulate a joint optimization problem to maximize MNO's profits, and develop an intelligent traffic control scheme by investigating DRL, which can improve system profits of the MNO and allocate network resources effectively. Experimental results based on real traffic data demonstrate our designed system is efficient and well-performed.\",\n \"Title: Blockchain-Enabled Intelligent Transportation Systems: A Distributed Crowdsensing Framework\\nYear: 2022\\n\\nAbstract: Intelligent Transportation System (ITS) is critical to cope with traffic events, e.g., traffic jams and accidents, and provide services for personal traveling. However, existing researches have not jointly considered the user data safety, utility and system latency comprehensively, to the best of our knowledge. Since both safe and efficient transmissions are significant for ITS, we construct a blockchain-enabled crowdsensing framework for distributed traffic management. First, we illustrate the system model and formulate a multi-objective optimization problem. Due to its complexity, we decompose it into two subproblems, and propose the corresponding schemes, i.e., a Deep Reinforcement Learning (DRL)-based algorithm and a DIstributed Alternating Direction mEthod of Multipliers (DIADEM) algorithm. Extensive experiments are carried out to evaluate the performance of our solutions, and experimental results demonstrate that the DRL-based algorithm can legitimately select active miners and transactions to make a satisfied trade-off between the blockchain safety and latency, and the DIADEM algorithm can effectively select task computation modes for vehicles in a distributed way to maximize their social welfare.\",\n \"Title: Internet of UAVs Based Remote Health Monitoring: An Online eHealth System\\nYear: 2021\\n\\nAbstract: The recent COVID-19 pandemic has brought significant challenges to the traditional healthcare industry. A novel eHealth system is required to cope with infectious and chronic diseases. This article proposes an online eHealth system to monitor patients and provides edge computing services based on the Internet of Unmanned Aerial Vehicles (UAVs). In order to minimize the health monitoring latency an...\",\n \"Title: Edge Learning for Internet of Medical Things and Its COVID-19 Applications: A Distributed 3C Framework\\nYear: 2021\\n\\nAbstract: With the global outbreak of COVID-19, the Internet of Medical Things (IoMT), as an extension of the Internet of Things (IoT), has received increasing attention due to its ability to remotely monitor the main symptoms. In addition, based on widely collected IoMT data, the spread and even the origin of a pandemic can be traced effectively. However, spectrum resources become scarce with the increasin...\",\n \"Title: 5G-Enabled UAV-to-Community Offloading: Joint Trajectory Design and Task Scheduling\\nYear: 2021\\n\\nAbstract: Due to line-of-sight communication links and distributed deployment, Unmanned Aerial Vehicles (UAVs) have attracted substantial interest in agile Mobile Edge Computing (MEC) service provision. In this paper, by clustering multiple users into independent communities based on their geographic locations, we design a 5G-enabled UAV-to-community offloading system. A system throughput maximization probl...\",\n \"Title: Privacy-Preserved Electronic Medical Record Exchanging and Sharing: A Blockchain-Based Smart Healthcare System\\nYear: 2022\\n\\nAbstract: The digitization of Electronic Medical Record (EMR) provides potential access to a wealth of medical information, but also presents new challenges in privacy-preserved EMR exchanging and sharing. In this paper, we propose a blockchain-based smart healthcare system with fine-grained privacy protection for reliable data exchanging and sharing among different users. We design a blockchain-enabled dyn...\",\n \"Title: Distributed Task Scheduling for Wireless Powered Mobile Edge Computing: A Federated-Learning-Enabled Framework\\nYear: 2021\\n\\nAbstract: Sixth generation (6G) wireless communication networks are expected to provide ultra-low latency and energy-efficient services for global users. The paradigm of wireless powered mobile edge computing (WP-MEC) provides a feasible framework to real-ize the above purposes by leveraging the advantage of both wireless power transfer and MEC. Howev-er, massive network traffic and control information over...\",\n \"Title: Online Learning for Distributed Computation Offloading in Wireless Powered Mobile Edge Computing Networks\\nYear: 2022\\n\\nAbstract: A novel paradigm named Wireless Powered Mobile Edge Computing (WP-MEC) emerges recently, which integrates Mobile Edge Computing (MEC) and Wireless Power Transfer (WPT) technologies. It enables mobile clients to both extend their computing capacities by task offloading, and charge from edge servers via energy transmission. Existing studies generally focus on the centralized design of task scheduling and energy charging in WP-MEC networks. To meet the decentralization requirement of the near-coming 6G network, we propose an online learning algorithm for computation offloading in WP-MEC networks with a distributed execution manner. Specifically, we first define the delay minimization problem by considering task deadline and energy constraints. Then, we transform it into a primal-dual optimization problem based on the Bellman equation. After that, we design a novel neural model that learns both offloading and time division decisions in each time slot to solve the formulated optimization problem. To train and execute the designed algorithm distributivity, we form multiple learning models decentralized on edge servers and they work coordinately to achieve parameter synchronization. At last, both theoretical and performance analyses show that the designed algorithm has significant advantages in comparison with other representative schemes.\",\n \"Title: Blockchain-Enabled Electrical Fault Inspection and Secure Transmission in 5G Smart Grids\\nYear: 2022\\n\\nAbstract: The maturity of the 5th-Generation (5G) communication technology promotes a new round of industrial revolution and supports the high-quality development of economic society. However, owing to the scarce communication resources, costly labor and complex geographic environment, inspecting and maintaining electrical faults accurately and timely in a remote grid is rather challenging. To solve this problem, we comprehensively consider secure and efficient signal transmissions to construct an automatic grid fault inspection system and formulate a multi-objective optimization problem. Due to its complexity, we decompose it into two sub-problems, propose a \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">b</u>\\nlockchain-\\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">e</u>\\nnabled \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">s</u>\\necure \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">t</u>\\nransmission scheme (BEST) and an \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</u>\\nmproved \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">m</u>\\narket \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">m</u>\\natching (IMM) algorithm, correspondingly. Considering the latency magnitude difference between blockchain verification and intra-domain transmission, the BEST scheme integrates \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">d</u>\\neep \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">r</u>\\neinforcement learning-based \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</u>\\nmproved \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">p</u>\\nroximal policy optimization training algorithm (DRIP) and \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">A</u>\\n*-based \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">b</u>\\ni-\\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">o</u>\\nbjective multi-destination \\n<underline xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">o</u>\\nptimization algorithm (ABOO) to achieve the intra-domain secure transmission. Based on the real city topology and the YouTube video service data statistics, our algorithms can optimize the network performance while guaranteeing the security of signal transmissions.\",\n \"Title: Intelligent Fingerprint-Based Localization Scheme Using CSI Images for Internet of Things\\nYear: 2022\\n\\nAbstract: Fingerprint-based indoor localization methods have become an important technology because of their wide availability, low hardware costs, and the rapidly growing demand for location-based services. However, it is low precision of positioning and time-consuming for retraining the model when the fingerprint database has changed with new input samples. In this paper, we propose a novel intelligence localization scheme utilizing incremental learning without retraining models based on channel state information (CSI), namely ILCL. CSI phase data are extracted through a modified device driver, and we convert them into CSI images, which are the input to a convolutional neural network for training the weights in the offline stage. The estimated location is obtained by a probabilistic method based on a broad learning system (BLS) that can continue to train rapidly on new input data in the online stage. The ILCL architecture can be characterized as “deep” and “broad” and can further extract features. Experimental results confirm the superiority of ILCL compared with five existing algorithms in two real-world indoor environments with a total area is over 200 \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">${m}^{2}$</tex-math></inline-formula>\\n.\",\n \"Title: Blockchain-Enabled Privacy-Preserving Access Control for Data Publishing and Sharing in the Internet of Medical Things\\nYear: 2022\\n\\nAbstract: Recently, the rapid developments in the Internet of Medical Things (IoMT) enable smart devices to generate and transmit massive personal electronic medical records (EMRs). However, there are many sensitive attributes in an EMR, which could be accessed by external or internal unauthorized users for malicious purposes. In this article, we present a triple subject purpose-based access control (TS-PBAC) model, which is compatible with a blockchain-enabled reliable transaction network, and design an individual-centric security and privacy-preserving mechanism for access control with different purposes and roles in IoMT scenarios. Specifically, we design hierarchical purpose tree (HPT) and related policies to guarantee the legality of an external user with different purposes. To improve the privacy for sensitive attributes against an internal attacker, we design a local differential privacy (LDP)-based policy and role-based access control scheme in an edge computing paradigm to grant fine-granularity rights for authorized users. In addition, we introduce mutual evaluation metrics to evaluate data quality from a patient-and-medical-service level in an open anonymous network, only using logs kept in the blockchain. We test our approach by real-world EMRs with 100000 patients. The experimental results show that the proposed privacy-preserving scheme can better protect patient’s privacy than traditional access control policies in IoMT environments, and can make reliable and stable access control decisions between data publishers and data requesters with different purposes.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":97,"string":"97"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":259,"string":"259"}}},{"rowIdx":260,"cells":{"question_id":{"kind":"string","value":"Shuzhong Zhang"},"question":{"kind":"string","value":"Generate an abstract for the title \"New complexity results for the Iri-Imai method\" using the following items: linear programming, Iri-Imai algorithm, main iterations, modification, primal-dual potential function."},"answer":{"kind":"string","value":"In this paper, we show that the number of main iterations required by the Iri-Imai algorithm to solve a linear programming problem isO(nL). Moreover, we show that a modification of this algorithm requires only\n<img src=\"/fulltext-image.asp?format=htmlnonpaginated&src=BT50T51333674X7M_html\\10479_2005_Article_BF02206829_TeX2GIFIE1.gif\" border=\"0\" alt=\"\n$$\\mathcal{O}(\\sqrt {nL} )$$\n\" /> main iterations. In this modification, we measure progress by means of a primal-dual potential function."},"correct_answer":{"kind":"string","value":"In this paper, we show that the number of main iterations required by the Iri-Imai algorithm to solve a linear programming problem isO(nL). Moreover, we show that a modification of this algorithm requires only\n<img src=\"/fulltext-image.asp?format=htmlnonpaginated&src=BT50T51333674X7M_html\\10479_2005_Article_BF02206829_TeX2GIFIE1.gif\" border=\"0\" alt=\"\n$$\\mathcal{O}(\\sqrt {nL} )$$\n\" /> main iterations. In this modification, we measure progress by means of a primal-dual potential function."},"documents":{"kind":"list like","value":["Title: A unified adaptive co-identification framework for high-d expression data\nYear: 2012\n\nAbstract: High-throughput techniques are producing large-scale high-dimensional (e.g., 4D with genes vs timepoints vs conditions vs tissues) genome-wide gene expression data. This induces increasing demands for effective methods for partitioning the data into biologically relevant groups. Current clustering and co-clustering approaches have limitations, which may be very time consuming and work for only low-dimensional expression datasets. In this work, we introduce a new notion of \"co-identification\", which allows systematical identification of genes participating different functional groups under different conditions or different development stages. The key contribution of our work is to build a unified computational framework of co-identification that enables clustering to be high-dimensional and adaptive. Our framework is based upon a generic optimization model and a general optimization method termed Maximum Block Improvement. Testing results on yeast and Arabidopsis expression data are presented to demonstrate high efficiency of our approach and its effectiveness.","Title: Approximation algorithms for homogeneous polynomial optimization with quadratic constraints\nYear: 2010\n\nAbstract: In this paper, we consider approximation algorithms for optimizing a generic multi-variate homogeneous polynomial function, subject to homogeneous quadratic constraints. Such optimization models have wide applications, e.g., in signal processing, magnetic resonance imaging (MRI), data training, approximation theory, and portfolio selection. Since polynomial functions are non-convex, the problems under consideration are all NP-hard in general. In this paper we shall focus on polynomial-time approximation algorithms. In particular, we first study optimization of a multi-linear tensor function over the Cartesian product of spheres. We shall propose approximation algorithms for such problem and derive worst-case performance ratios, which are shown to be dependent only on the dimensions of the model. The methods are then extended to optimize a generic multi-variate homogeneous polynomial function with spherical constraint. Likewise, approximation algorithms are proposed with provable approximation performance ratios. Furthermore, the constraint set is relaxed to be an intersection of co-centered ellipsoids; namely, we consider maximization of a homogeneous polynomial over the intersection of ellipsoids centered at the origin, and propose polynomial-time approximation algorithms with provable worst-case performance ratios. Numerical results are reported, illustrating the effectiveness of the approximation algorithms studied.","Title: Multivariate Nonnegative Quadratic Mappings\nYear: 2004\n\nAbstract: In this paper, we study several issues related to the characterization of specific classes of multivariate quadratic mappings that are nonnegative over a given domain, with nonnegativity defined by a prespecified conic order. In particular, we consider the set (cone) of nonnegative quadratic mappings, defined with respect to the positive semidefinite matrix cone, and study when it can be represented by linear matrix inequalities. We also discuss the applications of the results in robust optimization, especially the robust quadratic matrix inequalities and the robust linear programming models. In the latter application the implementational errors of the solution are taken into account, and the problem is formulated as a semidefinite program.","Title: Sequencing jobs that require common resources on a single machine: A solvable case of the TSP\nYear: 1998\n\nAbstract: In this paper a one-machine scheduling model is analyzed wheren different jobs are classified intoK groups depending on which additional resource they require. The change-over time from one job to another consists of the removal time or of the set-up time of the two jobs. It is sequence-dependent in the sense that the change-over time is determined by whether or not the two jobs belong to the same group. The objective is to minimize the makespan. This problem can be modeled as an asymmetric Traveling Salesman Problem (TSP) with a specially structured distance matrix. For this problem we give a polynomial time solution algorithm that runs in O(n logn) time. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.","Title: Approximation Bounds for Quadratic Optimization with Homogeneous Quadratic Constraints\nYear: 2007\n\nAbstract: We consider the NP-hard problem of finding a minimum norm vector in $n$-dimensional real or complex Euclidean space, subject to $m$ concave homogeneous quadratic constraints. We show that a semidefinite programming (SDP) relaxation for this nonconvex quadratically constrained quadratic program (QP) provides an $O(m^2)$ approximation in the real case and an $O(m)$ approximation in the complex case. Moreover, we show that these bounds are tight up to a constant factor. When the Hessian of each constraint function is of rank $1$ (namely, outer products of some given so-called steering vectors) and the phase spread of the entries of these steering vectors are bounded away from $\\pi/2$, we establish a certain “constant factor” approximation (depending on the phase spread but independent of $m$ and $n$) for both the SDP relaxation and a convex QP restriction of the original NP-hard problem. Finally, we consider a related problem of finding a maximum norm vector subject to $m$ convex homogeneous quadratic constraints. We show that an SDP relaxation for this nonconvex QP provides an $O(1/\\ln(m))$ approximation, which is analogous to a result of Nemirovski &etal; [Math. Program., 86 (1999), pp. 463-473] for the real case.","Title: A New Self-Dual Embedding Method for Convex Programming\nYear: 2004\n\nAbstract: In this paper we introduce a conic optimization formulation to solve constrained convex programming, and propose a self-dual embedding model for solving the resulting conic optimization problem. The primal and dual cones in this formulation are characterized by the original constraint functions and their corresponding conjugate functions respectively. Hence they are completely symmetric. This allows for a standard primal-dual path following approach for solving the embedded problem. Moreover, there are two immediate logarithmic barrier functions for the primal and dual cones. We show that these two logarithmic barrier functions are conjugate to each other. The explicit form of the conjugate functions are in fact not required to be known in the algorithm. An advantage of the new approach is that there is no need to assume an initial feasible solution to start with. To guarantee the polynomiality of the path-following procedure, we may apply the self-concordant barrier theory of Nesterov and Nemirovski. For this purpose, as one application, we prove that the barrier functions constructed this way are indeed self-concordant when the original constraint functions are convex and quadratic. We pose as an open question to find general conditions under which the constructed barrier functions are self-concordant.","Title: Recursive approximation of the high dimensional max function\nYear: 2005\n\nAbstract: This paper proposes a smoothing method for the general n-dimensional max function, based on a recursive extension of smoothing functions for the two-dimensional max function. A theoretical framework is introduced, and some applications are discussed. Finally, a numerical comparison with a well-known smoothing method is presented.","Title: Tracking a Financial Benchmark Using a Few Assets\nYear: 2006\n\nAbstract: We study the problem of tracking a financial benchmarka continuously compounded growth rate or a stock market indexby dynamically managing a portfolio consisting of a small number of traded stocks in the market. In either case, we formulate the tracking problem as an instance of the stochastic linear quadratic control (SLQ), involving indefinite cost matrices. As the SLQ formulation involves a discounted objective over an infinite horizon, we first address the issue of stabilizability. We then use semidefinite programming (SDP) as a computational tool to generate the optimal feedback control. We present numerical examples involving stocks traded at the Hong Kong and New York Stock Exchanges to illustrate the various features of the model and its performance.","Title: Separated Continuous Conic Programming: Strong Duality and an Approximation Algorithm\nYear: 2009\n\nAbstract: Motivated by recent applications in robust optimization and in sign-constrained linear-quadratic control, we study in this paper a new class of optimization problems called separated continuous conic programming (SCCP). Focusing on a symmetric primal-dual pair, we develop a strong duality theory for the SCCP. Our idea is to use discretization to connect the SCCP and its dual to two ordinary conic programs. We show if the latter are strongly feasible and with finite optimal values, a condition that is readily verifiable, then the strong duality holds for the SCCP. This approach also leads to a polynomial-time approximation algorithm that solves the SCCP to any required accuracy.","Title: Tight Bounds for Some Risk Measures, with Applications to Robust Portfolio Selection\nYear: 2011\n\nAbstract: In this paper we develop tight bounds on the expected values of several risk measures that are of interest to us. This work is motivated by the robust optimization models arising from portfolio selection problems. Indeed, the whole paper is centered around robust portfolio models and solutions. The basic setting is to find a portfolio that maximizes (respectively, minimizes) the expected utility (respectively, disutility) values in the midst of infinitely many possible ambiguous distributions of the investment returns fitting the given mean and variance estimations. First, we show that the single-stage portfolio selection problem within this framework, whenever the disutility function is in the form of lower partial moments (LPM), or conditional value-at-risk (CVaR), or value-at-risk (VaR), can be solved analytically. The results lead to the solutions for single-stage robust portfolio selection models. Furthermore, the results also lead to a multistage adjustable robust optimization (ARO) solution when the disutility function is the second-order LPM. Exploring beyond the confines of convex optimization, we also consider the so-called S-shaped value function, which plays a key role in the prospect theory of Kahneman and Tversky. The nonrobust version of the problem is shown to be NP-hard in general. However, we present an efficient procedure for solving the robust counterpart of the same portfolio selection problem. In this particular case, the consideration of the robustness actually helps to reduce the computational complexity. Finally, we consider the situation whereby we have some additional information about the chance that a quadratic function of the random distribution reaches a certain threshold. That information helps to further reduce the ambiguity in the robust model. We show that the robust optimization problem in that case can be solved by means of semidefinite programming (SDP), if no more than two additional chance inequalities are to be incorporated.","Title: Complex Matrix Decomposition and Quadratic Programming\nYear: 2007\n\nAbstract: This paper studies the possibilities of the linear matrix inequality characterization of the matrix cones formed by nonnegative complex Hermitian quadratic functions over specific domains in the complex space. In its real-case analog, such studies were conducted in Sturm and Zhang [Sturm, J. F., S. Zhang. 2003. On cones of nonnegative quadratic functions. Math. Oper. Res.28 246--267]. In this paper it is shown that stronger results can be obtained for the complex Hermitian case. In particular, we show that the matrix rank-one decomposition result of Sturm and Zhang [Sturm, J. F., S. Zhang. 2003. On cones of nonnegative quadratic functions. Math. Oper. Res.28 246--267] can be strengthened for the complex Hermitian matrices. As a consequence, it is possible to characterize several new matrix co-positive cones (over specific domains) by means of linear matrix inequality. As examples of the potential application of the new rank-one decomposition result, we present an upper bound on the lowest rank among all the optimal solutions for a standard complex semidefinite programming (SDP) problem, and offer alternative proofs for a result of Hausdorff [Hausdorff, F. 1919. Der Wertvorrat einer Bilinearform. Mathematische Zeitschrift3 314--316] and a result of Brickman [Brickman, L. 1961. On the field of values of a matrix. Proc. Amer. Math. Soc.12 61--66] on the joint numerical range.","Title: Pivot rules for linear programming: A survey on recent theoretical developments\nYear: 1993\n\nAbstract: The purpose of this paper is to discuss the various pivot rules of the simplex method and its variants that have been developed in the last two decades, starting from the appearance of the minimal index rule of Bland. We are mainly concerned with finiteness properties of simplex type pivot rules. Well known classical results concerning the simplex method are not considered in this survey, but the connection between the new pivot methods and the classical ones, if there is any, is discussed.","Title: Global Error Bounds for Convex Conic Problems\nYear: 2000\n\nAbstract: This paper aims at deriving and proving some Lipschitzian-type error bounds for convex conic problems in a simple way. First, it is shown that if the recession directions satisfy Slater's condition, then a global Lipschitzian-type error bound holds. Alternatively, if the feasible region is bounded, then the ordinary Slater condition guarantees a global Lipschitzian-type error bound. These can be considered as generalizations of previously known results for inequality systems, which also follow from general results by Bauschke and Borwein in [ SIAM Review, 38 (1996), pp. 367--426] and Bauschke, Borwein, and Li in a 1997 report. However, the proofs in the current paper are considerably simpler. Some of the results are generalized to the intersection of multiple shifted cones (with different shifts). Under Slater's condition alone, a global Lipschitzian-type error bound does not hold. It is shown, however, that such an error bound holds for a specific conic region. For linear systems we establish that the sharp constant involved in Hoffman's error bound is nothing but the condition number for linear programming as used by Vavasis and Ye in [ Math. Programming, 74 (1996), pp. 79--120].","Title: No-boundary thinking in bioinformatics research.\nYear: 2013\n\nAbstract: Currently there are definitions from many agencies and research societies defining \"bioinformatics\" as deriving knowledge from computational analysis of large volumes of biological and biomedical data. Should this be the bioinformatics research focus? We will discuss this issue in this review article. We would like to promote the idea of supporting human-infrastructure (HI) with no-boundary thinking (NT) in bioinformatics (HINT).","Title: An O$(\\sqrtn L)$ Iteration Primal-dual Path-following Method, Based on Wide Neighborhoods and Large Updates, for Monotone LCP\nYear: 2005\n\nAbstract: In this paper we propose a new class of primal-dual path-following interior point algorithms for solving monotone linear complementarity problems. At each iteration, the method would select a target on the central path with a large update from the current iterate, and then the Newton method is used to get the search directions, followed by adaptively choosing the step sizes, which are, e.g., the largest possible steps before leaving a neighborhood that is as wide as the given ${\\cal N}^-_{\\infty}$ neighborhood. The only deviation from the classical approach is that we treat the classical Newton direction as the sum of two other directions, corresponding to, respectively, the negative part and the positive part of the right-hand side. We show that if these two directions are equipped with different and appropriate step sizes, then the method enjoys the low iteration bound of $O(\\sqrt{n}\\log L)$, where $n$ is the dimension of the problem and $L=\\frac{(x^0)^Ts^0}{\\ep}$ with $\\ep$ the required precision and $(x^0,s^0)$ the initial interior solution. For a predictor-corrector variant of the method, we further prove that, besides the predictor steps, each corrector step also reduces the duality gap by a rate of $1-1/O(\\sqrt{n})$. Additionally, if the problem has a strict complementary solution, then the predictor steps converge Q-quadratically.","Title: Complex Quadratic Optimization and Semidefinite Programming\nYear: 2006\n\nAbstract: In this paper we study the approximation algorithms for a class of discrete quadratic optimization problems in the Hermitian complex form. A special case of the problem that we study corresponds to the max-3-cut model used in a recent paper of Goemans and Williamson J. Comput. System Sci., 68 (2004), pp. 442-470]. We first develop a closed-form formula to compute the probability of a complex-valued normally distributed bivariate random vector to be in a given angular region. This formula allows us to compute the expected value of a randomized (with a specific rounding rule) solution based on the optimal solution of the complex semidefinite programming relaxation problem. In particular, we present an $[m^2(1-\\cos\\frac{2\\pi}{m})/8\\pi]$-approximation algorithm, and then study the limit of that model, in which the problem remains NP-hard. We show that if the objective is to maximize a positive semidefinite Hermitian form, then the randomization-rounding procedure guarantees a worst-case performance ratio of $\\pi/4 \\approx 0.7854$, which is better than the ratio of $2/\\pi \\approx 0.6366$ for its counterpart in the real case due to Nesterov. Furthermore, if the objective matrix is real-valued positive semidefinite with nonpositive off-diagonal elements, then the performance ratio improves to 0.9349.","Title: Robust Multicast Beamforming for Spectrum Sharing-Based Cognitive Radios\nYear: 2012\n\nAbstract: We consider a robust downlink beamforming optimization problem for secondary multicast transmission in a multiple-input multiple-output (MIMO) spectrum sharing cognitive radio (CR) network. The minimization of transmit power is formulated subject to both quality-of-service (QoS) constraints on the secondary receivers and interference temperature constraints on the primary users, under the assumption of imperfect channel state information (CSI). The problem is a nonconvex quadratically constrained quadratic program (QCQP), and in general it is hard to achieve the global optimality. As a compromise, we present two randomized approximation algorithms for the problem via convex optimization techniques. Apart from the general setting of the robust beamforming problem, we identify one interesting special case, the robust problem of which can be solved efficiently. Simulation results are presented to demonstrate the performance gains of the proposed algorithms over an existing robust design.","Title: Maximum Block Improvement and Polynomial Optimization\nYear: 2012\n\nAbstract: In this paper we propose an efficient method for solving the spherically constrained homogeneous polynomial optimization problem. The new approach has the following three main ingredients. First, we establish a block coordinate descent type search method for nonlinear optimization, with the novelty being that we accept only a block update that achieves the maximum improvement, hence the name of our new search method: maximum block improvement (MBI). Convergence of the sequence produced by the MBI method to a stationary point is proved. Second, we establish that maximizing a homogeneous polynomial over a sphere is equivalent to its tensor relaxation problem; thus we can maximize a homogeneous polynomial function over a sphere by its tensor relaxation via the MBI approach. Third, we propose a scheme to reach a KKT point of the polynomial optimization, provided that a stationary solution for the relaxed tensor problem is available. Numerical experiments have shown that our new method works very efficiently: for a majority of the test instances that we have experimented with, the method finds the global optimal solution at a low computational cost.","Title: A new framework for co-clustering of gene expression data\nYear: 2011\n\nAbstract: A new framework is proposed to study the co-clustering of gene expression data. This framework is based on a generic tensor optimization model and an optimization method termed Maximum Block Improvement (MBI) recently developed in [3]. Not only can this framework be applied for co-clustering gene expression data with genes expressed at different conditions represented in 2D matrices, but it can also be readily applied for co-clustering more complex high-dimensional gene expression data with genes expressed at different tissues, different development stages, different time points, different stimulations, etc. Moreover, the new framework is so flexible that it poses no difficulty at all to incorporate a variety of clustering quality measurements. In this paper, we demonstrate the effectiveness of this new approach by providing the details of one specific implementation of the algorithm, and presenting the experimental testing on microarray gene expression datasets. Our results show that the new algorithm is very efficient and it performs well for identifying patterns in gene expression datasets.","Title: Bounding Probability of Small Deviation: A Fourth Moment Approach\nYear: 2010\n\nAbstract: In this paper we study the problem of upper bounding the probability that a random variable is above its expected value by a small amount (relative to the expected value), by means of the second and the fourth (central) moments of the random variable. In this particular context, many classical inequalities yield only trivial bounds. We obtain tight upper bounds by studying the primal-dual moments-generating conic optimization problems. As an application, we demonstrate that given the new probability bounds, a substantial sharpening and simplification of a recent result and its analysis by Feige (see Feige, U. 2006. On sums of independent random variables with unbounded variances, and estimating the average degree in a graph. SIAM J. Comput.35 964--984) can be obtained; also, these bounds lead to new properties of the distribution of the cut values for the max-cut problem. We expect the new probability bounds to be useful in many other applications.","Title: On a Wide Region of Centers and Primal-Dual Interior Point Algorithms for Linear Programming\nYear: 1997\n\nAbstract: In the adaptive step primal-dual interior point method for linear programming, polynomial algorithms are obtained by computing Newton directions towards targets on the central path, and restricting the iterates to a neighborhood of this central path. In this paper, the adaptive step methodology is extended, by considering targets in a certain central region, which contains the usual central path, and subsequently generating iterates in a neighborhood of this region. The size of the central region can vary from the central path to the whole feasible region by choosing a certain parameter. An O√nL iteration bound is obtained under mild conditions on the choice of the target points. In particular, we leave plenty of room for experimentation with search directions. The practical performance of the new primal-dual interior point method is measured on part of the Netlib test set for various sizes of the central region.","Title: An interior point method, based on rank-1 updates, for linear programming\nYear: 1998\n\nAbstract: We propose a polynomial time primal—dual potential reduction algorithm for linear programming. The algorithm generates sequencesdk andvk rather than a primal—dual interior point (x k ,s k ), where\\(d_i^k = \\sqrt {{{x_i^k } \\mathord{\\left/ {\\vphantom {{x_i^k } {s_i^k }}} \\right. \\kern-\\nulldelimiterspace} {s_i^k }}} \\) and\\(v_i^k = \\sqrt {x_i^k s_i^k }\\) fori = 1, 2,⋯,n. Only one element ofdk is changed in each iteration, so that the work per iteration is bounded by O(mn) using rank-1 updating techniques. The usual primal—dual iteratesxk andsk are not needed explicitly in the algorithm, whereasdk andvk are iterated so that the interior primal—dual solutions can always be recovered by aforementioned relations between (xk, sk) and (dk, vk) with improving primal—dual potential function values. Moreover, no approximation ofdk is needed in the computation of projection directions. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.","Title: Stochastic Linear-Quadratic Control via Primal-Dual Semidefinite Programming.\nYear: 2004\n\nAbstract: We study stochastic linear-quadratic (LQ) optimal control problems over an infinite time horizon, allowing the cost matrices to be indefinite. We develop a systematic approach based on semidefinite programming (SDP). A central issue is the stability of the feedback control. We show that this can be effectively examined through the complementary duality of the SDP. Furthermore, we establish several implication relations among the SDP complementary duality, the (generalized) Riccati equation, and the optimality of the LQ control problem. Based on these relations, we propose a numerical procedure that provides a thorough treatment of the LQ control problem via primal-dual SDP: it identifies a stabilizing feedback control that is optimal or determines that the problem possesses no optimal solution. For the latter case, we develop an E-approximation scheme that is asymptotically optimal.","Title: A $${\\mathsf{D}}$$-induced duality and its applications\nYear: 2008\n\nAbstract: This paper attempts to extend the notion of duality for convex cones, by basing it on a prescribed conic ordering and a fixed\n bilinear mapping. This is an extension of the standard definition of dual cones, in the sense that the nonnegativity of the inner-product is replaced by a pre-specified conic ordering, defined by a convex cone $${\\mathsf{D}}$$ , and the inner-product itself is replaced by a general multi-dimensional bilinear mapping. This new type of duality is termed\n the $${\\mathsf{D}}$$-induced duality in the paper. We further introduce the notion of $${\\mathsf{D}}$$-induced polar sets within the same framework, which can be viewed as a generalization of the $${\\mathsf{D}}$$-induced dual cones and is convenient to use for some practical applications. Properties of the extended duality, including\n the extended bi-polar theorem, are proven. Furthermore, attention is paid to the computation and approximation of the $${\\mathsf{D}}$$ -induced dual objects. We discuss, as examples, applications of the newly introduced $${\\mathsf{D}}$$-induced duality concepts in robust conic optimization and the duality theory for multi-objective conic optimization.","Title: On the long-step path-following method for semidefinite programming\nYear: 1998\n\nAbstract: It has been shown in various recent research reports that the analysis of short-step primal-dual path following algorithms for linear programming can be nicely generalized to semidefinite programming. However, the analysis of long-step path-following algorithms for semidefinite programming appeared to be less straightforward. For such an algorithm, Monteiro (1997) obtained an O(n^1^.^5log(1/@e)) iteration bound for obtaining an @e-optimal solution, where n is the order of the semidefinite decision variable. In this paper, we propose to use a different search direction, viz. the so-called V-space direction. It is shown that this modification reduces the iteration complexity to O(nlog(1/@e)). Independently, Monteiro and Y. Zhang obtained a similar result using Nesterov-Todd directions.","Title: Design of phase codes for radar performance optimization with a similarity constraint\nYear: 2009\n\nAbstract: This paper deals with the design of coded waveforms which optimize radar performances in the presence of colored Gaussian disturbance. We focus on the class of phase coded pulse trains and determine the radar code which approximately maximizes the detection performance under a similarity constraint with a prefixed radar code. This is tantamount to forcing a similarity between the ambiguity functions of the devised waveform and of the pulse train encoded with the prefixed sequence. We consider the cases of both continuous and finite phase alphabet, and formulate the code design in terms of a nonconvex, NP-hard quadratic optimization problem. In order to approximate the optimal solutions, we propose techniques (with polynomial computational complexity) based on the method of semidefinite program (SDP) relaxation and randomization. Moreover, we also derive approximation bounds yielding a \"measure of goodness\" of the devised algorithms. At the analysis stage, we assess the performance of the new encoding techniques both in terms of detection performance and ambiguity function, under different choices for the similarity parameter. We also show that the new algorithms achieve an accurate approximation of the optimal solution with a modest number of randomizations.","Title: Foreword: Special issue on large-scale nonlinear and semidefinite programming.\nYear: 2007\n\nAbstract: Without Abstract","Title: Sparse solutions to random standard quadratic optimization problems.\nYear: 2013\n\nAbstract: The standard quadratic optimization problem (StQP) refers to the problem of minimizing a quadratic form over the standard simplex. Such a problem arises from numerous applications and is known to be NP-hard. In this paper we focus on a special scenario of the StQP where all the elements of the data matrix Q are independently identically distributed and follow a certain distribution such as uniform or exponential distribution. We show that the probability that such a random StQP has a global optimal solution with k nonzero elements decays exponentially in k. Numerical evaluation of our theoretical finding is discussed as well.","Title: Strong Duality for the CDT Subproblem: A Necessary and Sufficient Condition\nYear: 2009\n\nAbstract: In this paper, we consider the problem of minimizing a nonconvex quadratic function, subject to two quadratic inequality constraints. As an application, such a quadratic program plays an important role in the trust region method for nonlinear optimization; such a problem is known as the Celis, Dennis, and Tapia (CDT) subproblem in the literature. The Lagrangian dual of the CDT subproblem is a semidefinite program (SDP), hence convex and solvable. However, a positive duality gap may exist between the CDT subproblem and its Lagrangian dual because the CDT subproblem itself is nonconvex. In this paper, we present a necessary and sufficient condition to characterize when the CDT subproblem and its Lagrangian dual admits no duality gap (i.e., the strong duality holds). This necessary and sufficient condition is easy verifiable and involves only one (any) optimal solution of the SDP relaxation for the CDT subproblem. Moreover, the condition reveals that it is actually rare to render a positive duality gap for the CDT subproblems in general. Moreover, if the strong duality holds, then an optimal solution for the CDT problem can be retrieved from an optimal solution of the SDP relaxation, by means of a matrix rank-one decomposition procedure. The same analysis is extended to the framework where the necessary and sufficient condition is presented in terms of the Lagrangian multipliers at a KKT point. Furthermore, we show that the condition is numerically easy to work with approximatively.","Title: On weighted centers for semidefinite programming\nYear: 2000\n\nAbstract: In this paper, we generalize the notion of weighted centers to semidefinite programming. Our analysis fits in the v-space framework, which is purely based on the symmetric primal–dual transformation and does not make use of barriers. Existence and scale invariance properties are proven for the weighted centers. Relations with other primal–dual maps are discussed.","Title: Robust secondary multicast transmit beamforming for cognitive radio networks under imperfect channel state information.\nYear: 2011\n\nAbstract: Consider a robust downlink beamforming optimization problem for secondary multicast transmission in a multiple-input multiple-output (MIMO) spectrum sharing cognitive radio (CR) network. The minimization problem of transmit power is formulated subject to both the quality-of-service (QoS) constraints on the secondary receivers and the interference temperature constraints on the primary users, under the assumption of imperfect channel state information (CSI). The problem is non-convex quadratically constrained quadratic program (QCQP), and it is hard to achieve the global optimality. As a compromise, we present a randomized approximation algorithm for the problem via convex optimization techniques. In particular, we point out that the robust beamforming problem is efficiently solvable when the number of primary and secondary links in the CR network is not larger than three. Simulation results are presented to demonstrate the performance gains of the proposed algorithm over an existing robust design.","Title: Duality gap estimation and polynomial time approximation for optimal spectrum management\nYear: 2009\n\nAbstract: Consider a communication system whereby multiple users share a common frequency band and must choose their transmit power spectra jointly in response to physical channel conditions including the effects of interference. The goal of the users is to maximize a system-wide utility function (e.g., weighted sum-rate of all users), subject to individual power constraints. A popular approach to solve the discretized version of this nonconvex problem is by Lagrangian dual relaxation. Unfortunately the discretized spectrum management problem is NP-hard and its Lagrangian dual is in general not equivalent to the primal formulation due to a positive duality gap. In this paper, we use a convexity result of Lyapunov to estimate the size of duality gap for the discretized spectrum management problem and show that the duality gap vanishes asymptotically at the rate O(1/√N), where N is the size of the uniform discretization of the shared spectrum. If the channels are frequency flat, the duality gap estimate improves to O(1/N). Moreover, when restricted to the FDMA spectrum sharing strategies, we show that the Lagrangian dual relaxation, combined with a linear programming scheme, can generate an ε-optimal solution for the continuous formulation of the spectrum management problem in polynomial time for any ε O.","Title: Quadratic maximization and semidefinite relaxation\nYear: 2000\n\nAbstract: . In this paper we study a class of quadratic maximization problems and their semidefinite programming (SDP) relaxation. For\n a special subclass of the problems we show that the SDP relaxation provides an exact optimal solution. Another subclass, which\n is ??-hard, guarantees that the SDP relaxation yields an approximate solution with a worst-case performance ratio of 0.87856....\n This is a generalization of the well-known result of Goemans and Williamson for the maximum-cut problem. Finally, we discuss\n extensions of these results in the presence of a certain type of sign restrictions.","Title: Semidefinite Relaxation Bounds for Indefinite Homogeneous Quadratic Optimization\nYear: 2008\n\nAbstract: This paper studies the relationship between the optimal value of a homogeneous quadratic optimization problem and its semidefinite programming (SDP) relaxation. We consider two quadratic optimization models: (1) $\\min \\{ x^* C x \\mid x^* A_k x \\ge 1, k=0,1,\\ldots,m, x\\in\\mathbb{F}^n\\}$ and (2) $\\max \\{ x^* C x \\mid x^* A_k x \\le 1, k=0,1,\\ldots,m, x\\in\\mathbb{F}^n\\}$, where $\\mathbb{F}$ is either the real field $\\mathbb{R}$ or the complex field $\\mathbb{C}$, and $A_k,C$ are symmetric matrices. For the minimization model (1), we prove that if the matrix $C$ and all but one of the $A_k$'s are positive semidefinite, then the ratio between the optimal value of (1) and its SDP relaxation is upper bounded by $O(m^2)$ when $\\mathbb{F}=\\mathbb{R}$, and by $O(m)$ when $\\mathbb{F}=\\mathbb{C}$. Moreover, when two or more of the $A_k$'s are indefinite, this ratio can be arbitrarily large. For the maximization model (2), we show that if $C$ and at most one of the $A_k$'s are indefinite while other $A_k$'s are positive semidefinite, then the ratio between the optimal value of (2) and its SDP relaxation is bounded from below by $O(1/\\log m)$ for both the real and the complex case. This result improves the bound based on the so-called approximate S-Lemma of Ben-Tal, Nemirovski, and Roos [SIAM J. Optim., 13 (2002), pp. 535-560]. When two or more of the $A_k$'s in (2) are indefinite, we derive a general bound in terms of the problem data and the SDP solution. For both optimization models, we present examples to show that the derived approximation bounds are essentially tight.","Title: New Results on Quadratic Minimization\nYear: 2003\n\nAbstract: In this paper we present several new results on minimizing an indefinite quadratic function under quadratic/linear constraints. The emphasis is placed on the case in which the constraints are two quadratic inequalities. This formulation is termed the extended trust region subproblem in this paper, to distinguish it from the ordinary trust region subproblem, in which the constraint is a single ellipsoid. The computational complexity of the extended trust region subproblem in general is still unknown. In this paper we consider several interesting cases related to this problem and show that for those cases the corresponding semidefinite programming relaxation admits no gap with the true optimal value, and consequently we obtain polynomial-time procedures for solving those special cases of quadratic optimization. For the extended trust region subproblem itself, we introduce a parameterized problem and prove the existence of a trajectory that will lead to an optimal solution. Combining this with a result obtained in the first part of the paper, we propose a polynomial-time solution procedure for the extended trust region subproblem arising from solving nonlinear programs with a single equality constraint.","Title: New results on Hermitian matrix rank-one decomposition\nYear: 2011\n\nAbstract: In this paper, we present several new rank-one decomposition theorems for Hermitian positive semidefinite matrices, which generalize our previous results in Huang and Zhang (Math Oper Res 32(3):758–768, 2007), Ai and Zhang (SIAM J Optim 19(4):1735–1756, 2009). The new matrix rank-one decomposition theorems appear to have wide applications in theory as well as in practice. On the theoretical side, for example, we show how to further extend some of the classical results including a lemma due to Yuan (Math Program 47:53–63, 1990), the classical results on the convexity of the joint numerical ranges (Pang and Zhang in Unpublished Manuscript, 2004; Au-Yeung and Poon in Southeast Asian Bull Math 3:85–92, 1979), and the so-called Finsler’s lemma (Bohnenblust in Unpublished Manuscript; Au-Yeung and Poon in Southeast Asian Bull Math 3:85–92, 1979). On the practical side, we show that the new results can be applied to solve two typical problems in signal processing and communication: one for radar code optimization and the other for robust beamforming. The new matrix decomposition theorems are proven by construction in this paper, and we demonstrate that the constructive procedures can be implemented efficiently, stably, and accurately. The URL of our Matlab programs is given in this paper. We strongly believe that the new decomposition procedures, as a means to solve non-convex quadratic optimization with a few quadratic constraints, are useful for many other potential engineering applications.","Title: On the Low Rank Solutions for Linear Matrix Inequalities\nYear: 2008\n\nAbstract: In this paper we present a polynomial-time procedure to find a low-rank solution for a system of linear matrix inequalities (LMI). The existence of such a low-rank solution was shown in the work of Au-Yeung and Poon and the work of Barvinok. In the approach of Au-Yeung and Poon an earlier unpublished manuscript of Bohnenblust played an essential role. Both proofs in the work of Au-Yeung and Poon and that of Barvinok are nonconstructive in nature. The aim of this paper is to provide a polynomial-time constructive procedure to find such a low-rank solution approximatively. Extensions of our new results and their relations to some of the known results in the literature are discussed.","Title: On distributional robust probability functions and their computations.\nYear: 2014\n\nAbstract: •Introduce “distributional robust probability function” with input moments.•Revisit worst case VaR-portfolio with a new concept (i.e. the existence of zeta).•Introduce new computational methods for joint probability moment bounds.•The new method is exact, while only approximation is available currently.•Three applications are introduced for risk management purposes.","Title: Robust portfolio selection based on a multi-stage scenario tree\nYear: 2008\n\nAbstract: The aim of this paper is to apply the concept of robust optimization introduced by Bel-Tal and Nemirovski to the portfolio selection problems based on multi-stage scenario trees. The objective of our portfolio selection is to maximize an expected utility function value (or equivalently, to minimize an expected disutility function value) as in a classical stochastic programming problem, except that we allow for ambiguities to exist in the probability distributions along the scenario tree. We show that such a problem can be formulated as a finite convex program in the conic form, on which general convex optimization techniques can be applied. In particular, if there is no short-selling, and the disutility function takes the form of semi-variance downside risk, and all the parameter ambiguity sets are ellipsoidal, then the problem becomes a second order cone program, thus tractable. We use SeDuMi to solve the resulting robust portfolio selection problem, and the simulation results show that the robust consideration helps to reduce the variability of the optimal values caused by the parameter ambiguity.","Title: The Role of Robust Optimization in Single-Leg Airline Revenue Management\nYear: 2009\n\nAbstract: In this paper, we introduce robust versions of the classical static and dynamic single-leg seat allocation models. These robust models take into account the inaccurate estimates of the underlying probability distributions. As observed by simulation experiments, it turns out that for these robust versions the variability compared to their classical counterparts is considerably reduced with a negligible decrease in average revenue.","Title: Code Design to Optimize Radar Detection Performance Under Accuracy and Similarity Constraints\nYear: 2008\n\nAbstract: This paper deals with the design of coded waveforms which optimize radar performances in the presence of colored Gaussian disturbance. We focus on the class of linearly coded pulse trains and determine the optimum radar code according to the following criterion: maximization of the detection performance under a control on the region of achievable Doppler estimation accuracies, and imposing a similarity constraint with a prefixed radar code. This last constraint is tantamount to requiring a similarity between the ambiguity functions of the devised waveform and of the pulse train encoded with the prefixed sequence. The resulting optimization problem is nonconvex and quadratic. In order to solve it, we propose a technique (with polynomial computational complexity) based on the relaxation of the original problem into a semidefinite program. Thus, the best code is determined through a rank-one decomposition of an optimal solution of the relaxed problem. At the analysis stage, we assess the performance of the new encoding technique in terms of detection performance, region of achievable Doppler estimation accuracies, and ambiguity function.","Title: On cones of nonnegative quadratic functions\nYear: 2003\n\nAbstract: We derive linear matrix inequality (LMI) characterizations and dual decomposition algorithms for certain matrix cones which are generated by a given set using generalized co-positivity. These matrix cones are in fact cones of nonconvex quadratic functions that are nonnegative on a certain domain. As a domain, we consider for instance the intersection of a (upper) level-set of a quadratic function and a half-plane. Consequently, we arrive at a generalization of Yakubovich's S-procedure result. Although the primary concern of this paper is to characterize the matrix cones by LMIs, we show, as an application of our results, that optimizing a general quadratic function over the intersection of an ellipsoid and a half-plane can be formulated as semidefinite programming (SDP), thus proving the polynomiality of this class of optimization problems, which arise, e.g., from the application of the trust region method for nonlinear programming. Other applications are in control theory and robust optimization.","Title: A Semidefinite Relaxation Scheme for Multivariate Quartic Polynomial Optimization with Quadratic Constraints\nYear: 2010\n\nAbstract: We present a general semidefinite relaxation scheme for general $n$-variate quartic polynomial optimization under homogeneous quadratic constraints. Unlike the existing sum-of-squares approach which relaxes the quartic optimization problems to a sequence of (typically large) linear semidefinite programs (SDP), our relaxation scheme leads to a (possibly nonconvex) quadratic optimization problem with linear constraints over the semidefinite matrix cone in $\\mathbb{R}^{n\\times n}$. It is shown that each $\\alpha$-factor approximate solution of the relaxed quadratic SDP can be used to generate in randomized polynomial time an $O(\\alpha)$-factor approximate solution for the original quartic optimization problem, where the constant in $O(\\cdot)$ depends only on problem dimension. In the case where only one positive definite quadratic constraint is present in the quartic optimization problem, we present a randomized polynomial time approximation algorithm which can provide a guaranteed relative approximation ratio of $(1-O(n^{-2}))$.","Title: Low-complexity algorithms for sequencing jobs with a fixed number of job-classes\nYear: 1996\n\nAbstract: In this paper we consider the problem of scheduling n jobs such that makespan is minimized. It is assumed that the jobs can be divided into K job-classes and that the change-over time between two consecutive jobs depends on the job-classes to which the two jobs belong. In this setting, we discuss the one machine scheduling problem with arbitrary processing times and the parallel machines scheduling problem with identical processing times. In both cases it is assumed that the number of job-classes K is fixed. By using an appropriate integer programming formulation with a fixed number of variables and constraints, it is shown that these two problems are solvable in polynomial time. For the one machine scheduling case it is shown that the complexity of our algorithm is linear in the number of jobs n . Moreover, if the problem is encoded according to the high multiplicity model of Hochbaum and Shamir, the time complexity of the algorithm is shown to be a polynomial in log n . In the parallel machine scheduling case, it is shown that if the number of machines is fixed the same results hold.","Title: Fractional QCQP With Applications in ML Steering Direction Estimation for Radar Detection\nYear: 2011\n\nAbstract: This paper deals with the problem of estimating the steering direction of a signal, embedded in Gaussian disturbance, under a general quadratic inequality constraint, representing the uncertainty region of the steering. We resort to the maximum likelihood (ML) criterion and focus on two scenarios. The former assumes that the complex amplitude of the useful signal component fluctuates from snapshot to snapshot. The latter supposes that the useful signal keeps a constant amplitude within all the snapshots. We prove that the ML criterion leads in both cases to a fractional quadratically constrained quadratic problem (QCQP). In order to solve it, we first relax the problem into a constrained fractional semidefinite programming (SDP) problem which is shown equivalent, via the Charnes-Cooper transformation, to an SDP problem. Then, exploiting a suitable rank-one decomposition, we show that the SDP relaxation is tight and give a procedure to construct (in polynomial time) an optimal solution of the original problem from an optimal solution of the fractional SDP. We also assess the quality of the derived estimator through a comparison between its performance and the constrained Cramer Rao lower Bound (CRB). Finally, we give two applications of the proposed theoretical framework in the context of radar detection.","Title: Lorentz-Positive Maps and Quadratic Matrix Inequalities With Applications to Robust MISO Transmit Beamforming\nYear: 2013\n\nAbstract: Consider a unicast downlink beamforming optimization problem with robust signal-to-interference-plus-noise ratio constraints to account for imperfect channel state information at the base station in a multiple-input single-output (MISO) communication system. The convexity of this robust beamforming problem remains unknown. A slightly conservative version of the robust beamforming problem is thus studied herein as a compromise. It is in the form of a semi-infinite second-order cone program (SOCP) and, more importantly, it possesses an equivalent and explicit convex reformulation, due to a linear matrix inequality (LMI) description of the cone of Lorentz-positive maps. Hence, the conservative robust beamforming problem can be efficiently solved by an optimization solver. Additional robust shaping constraints can also be easily handled to control the amount of interference generated on other co-existing users such as in cognitive radio systems.","Title: Lorentz-positive mapswith applications to robust MISO downlink beamforming\nYear: 2012\n\nAbstract: Consider a unicast downlink beamforming optimization problem with robust signal-to-interference-plus-noise ratio constraints to account for non-perfect channel state information at the base station. The convexity of the robust beamforming problem remains unknown. A slightly conservative version of the robust beamforming problem is thus studied herein as a compromise. It is in the form of a semi-infinite second-order cone program (SOCP), and more importantly, it possesses an equivalent and explicit convex reformulation, due to an linear matrix inequality description of the cone of Lorentz-positive maps. Hence the robust beamforming problem can be efficiently solved by an optimization solver. The simulation results show that the conservativeness of the robust form of semi-infinite SOCP is appropriate in terms of problem feasibility rate and the average transmission power.","Title: Optimal Linear Decentralized Estimation In A Bandwidth Constrained Sensor Network\nYear: 2005\n\nAbstract: Consider a bandwidth constrained sensor network in which a set of distributed sensors and a fusion center (FC) collaborate to estimate an unknown vector. Due to power and cost limitations, each sensor must compress its data in order to minimize the amount of information that need to be communicated to the FC. In this paper, we consider the design of a linear decentralized estimation scheme (DES) whereby each sensor transmits over a noisy channel to the FC a fixed number of real-valued messages which are linear functions of its observations, while the FC linearly combines the received messages to estimate the unknown parameter vector. Assuming each sensor collects data according to a local linear model, we propose to design optimal linear message functions and linear fusion function according to the minimum mean squared error (NMSE) criterion. We show that the resulting design problem is nonconvex and NP-hard in general, and identify two special cases for which the optimal linear DES design problem can be efficiently solved either in closed form or by Semi-definite programming (SDP).","Title: Stochastic Linear-Quadratic Control via Semidefinite Programming\nYear: 2001\n\nAbstract: We study stochastic linear-quadratic (LQ) optimal control problems over an infinite time horizon, allowing the cost matrices to be indefinite. We develop a systematic approach based on semidefinite programming (SDP). A central issue is the stability of the feedback control; and we show this can be effectively examined through the complementary duality of the SDP. Furthermore, we establish several implication relations among the SDP complementary duality, the (generalized) Riccati equation, and the optimality of the LQ control problem. Based on these relations, we propose a numerical procedure that provides a thorough treatment of the LQ control problem via primal-dual SDP: it identifies a stabilizing feedback control that is optimal or determines that the problem possesses no optimal solution. For the latter case, we develop an $\\epsilon$-approximation scheme that is asymptotically optimal.","Title: A Primal-Dual Decomposition Algorithm for Multistage Stochastic Convex Programming\nYear: 2005\n\nAbstract: This paper presents a new and high performance solution method for multistage stochastic convex programming. Stochastic programming is a quantitative tool developed in the field of optimization to cope with the problem of decision-making under uncertainty. Among others, stochastic programming has found many applications in finance, such as asset-liability and bond-portfolio management. However, many stochastic programming applications still remain computationally intractable because of their overwhelming dimensionality. In this paper we propose a new decomposition algorithm for multistage stochastic programming with a convex objective and stochastic recourse matrices, based on the path-following interior point method combined with the homogeneous self-dual embedding technique. Our preliminary numerical experiments show that this approach is very promising in many ways for solving generic multistage stochastic programming, including its superiority in terms of numerical efficiency, as well as the flexibility in testing and analyzing the model.","Title: Code design for radar STAP via optimization theory\nYear: 2010\n\nAbstract: In this paper, we deal with the problem of constrained code optimization for radar space-time adaptive processing (STAP) in the presence of colored Gaussian disturbance. At the design stage, we devise a code design algorithm complying with the following optimality criterion: maximization of the detection performance under a control on the regions of achievable values for the temporal and spatial Doppler estimation accuracy, and on the degree of similarity with a pre-fixed radar code. The resulting quadratic optimization problem is solved resorting to a convex relaxation that belongs to the semidefinite program (SDP) class. An optimal solution of the initial problem is then constructed through a suitable rank-one decomposition of an optimal solution of the relaxed one. At the analysis stage, we assess the performance of the new algorithm both on simulated data and on the standard challenging the Knowledge-Aided Sensor Signal Processing and Expert Reasoning (KASSPER) datacube.","Title: New variants of finite criss-cross pivot algorithms for linear programming\nYear: 1999\n\nAbstract: In this paper we generalize the so-called first-in-last-out pivot rule and the most-often-selected-variable pivot rule for the simplex method, as proposed in S. Zhang (Operations Research Letters 10 (1991) 189–192) to the criss-cross pivot setting where neither the primal nor the dual feasibility is preserved. The finiteness of the new criss-cross pivot variants is proven.","Title: On a Profit Maximizing Location Model\nYear: 2001\n\nAbstract: In this paper we discuss a locational model with a profit-maximizing objective. The model can be illustrated by the following situation. There is a set of potential customers in a given region. A firm enters the market and wants to sell a certain product to this set of customers. The location and demand of each potential customer are assumed to be known. In order to maximize its total profit, the firm has to decide: (1) where to locate its distribution warehouse to serve the customers; (2) the price for its product. Due to existence of competition, each customer holds a reservation price for the product. This reservation price is a decreasing function in the distance to the warehouse. If the actual price is higher than the reservation price, then the customer will turn to some other supplier and hence is lost from the firm's market. The problem of the firm is to find the best location for its warehouse and the best price for its product at the same time in order to maximize the total profit. We show that under certain assumptions on the complexity counts, a special case of this problem can be solved in polynomial time.","Title: Dynamic Spectrum Management: Complexity and Duality\nYear: 2008\n\nAbstract: Consider a communication system whereby multiple users share a common frequency band and must choose their transmit power spectral densities dynamically in response to physical channel conditions. Due to co-channel interference, the achievable data rate of each user depends on not only the power spectral density of its own, but also those of others in the system. Given any channel condition and as...","Title: Semidefinite Relaxation of Quadratic Optimization Problems\nYear: 2010\n\nAbstract: In this article, we have provided general, comprehensive coverage of the SDR technique, from its practical deployments and scope of applicability to key theoretical results. We have also showcased several representative applications, namely MIMO detection, B¿ shimming in MRI, and sensor network localization. Another important application, namely downlink transmit beamforming, is described in [1]. Due to space limitations, we are unable to cover many other beautiful applications of the SDR technique, although we have done our best to illustrate the key intuitive ideas that resulted in those applications. We hope that this introductory article will serve as a good starting point for readers who would like to apply the SDR technique to their applications, and to locate specific references either in applications or theory.","Title: Approximation algorithm for facility location with service installation costs\nYear: 2008\n\nAbstract: In this paper, we study the uncapacitated facility location problem with service installation costs depending on the type of service required. We propose a polynomial-time approximation algorithm with approximation ratio 1.808 which improves the previous approximation ratio of 2.391 of Shmoys, Swamy, and Levi.","Title: On a generalized Cournot oligopolistic competition game\nYear: 2013\n\nAbstract: We consider a model whereby players compete for a set of shared resources to produce and sell substitute products in the same market, which can be viewed as a generalization of the classical Cournot oligopolistic competition model, or, from a different angle, the Wardrop type routing model. In particular, we suppose that there are K players, who compete for the usage of resources as well as the sales of the end-products. Moreover, the unit costs of the shared resources and the selling prices of the products are assumed to be affine linear functions in the consumption/production quantities. We show that the price of anarchy in this case is lower bounded by 1/K, and this bound is essentially tight, which manifests the harsh nature of the competitive market for the producers.","Title: Polymatroid Optimization, Submodularity, and Joint Replenishment Games\nYear: 2012\n\nAbstract: In this paper we consider the problem of maximizing a separable concave function over a polymatroid. More specifically, we study the submodularity of its optimal objective value in the parameters of the objective function. This question is interesting in its own right and is encountered in many applications. But our research has been motivated mainly by a cooperative game associated with the well-known joint replenishment model. By applying our general results on polymatroid optimization, we prove that this cooperative game is submodular (i.e., its characteristic cost function is submodular) if the joint setup cost is a normalized and nondecreasing submodular function. Furthermore, the same result holds true for a more general one-warehouse multiple retailer game, which affirmatively answers an open question posed by Anily and Haviv [Anily, S., M. Haviv. 2007. The cost allocation problem for the first order interaction joint replenishment model. Oper. Res.55(2) 292--302].","Title: A Network Airline Revenue Management Framework Based on Decomposition by Origins and Destinations\nYear: 2014\n\nAbstract: We propose a framework for solving airline revenue management problems on large networks, where the main concern is to allocate the flight leg capacities to customer requests under fixed class fares. This framework is based on a mathematical programming model that decomposes the network into origin-destination pairs so that each pair can be treated as a single flight-leg problem. We first discuss that the proposed framework is quite generic in the sense that not only several well-known models from the literature fit into this framework, but also many single flight-leg models can be easily extended to a network setting through the prescribed construction. Then, we analyze the structure of the overall mathematical programming model and establish its relationship with other models frequently used in practice. The application of the proposed framework is illustrated through two examples based on static and dynamic single-leg models, respectively. These illustrative examples are then benchmarked against several existing methods on a set of real-life network problems.","Title: Tensor principal component analysis via convex optimization.\nYear: 2015\n\nAbstract: This paper is concerned with the computation of the principal components for a general tensor, known as the tensor principal component analysis (PCA) problem. We show that the general tensor PCA problem is reducible to its special case where the tensor in question is super-symmetric with an even degree. In that case, the tensor can be embedded into a symmetric matrix. We prove that if the tensor is rank-one, then the embedded matrix must be rank-one too, and vice versa. The tensor PCA problem can thus be solved by means of matrix optimization under a rank-one constraint, for which we propose two solution methods: (1) imposing a nuclear norm penalty in the objective to enforce a low-rank solution; (2) relaxing the rank-one constraint by semidefinite programming. Interestingly, our experiments show that both methods can yield a rank-one solution for almost all the randomly generated instances, in which case solving the original tensor PCA problem to optimality. To further cope with the size of the resulting convex optimization models, we propose to use the alternating direction method of multipliers, which reduces significantly the computational efforts. Various extensions of the model are considered as well.","Title: Approximation methods for complex polynomial optimization\nYear: 2014\n\nAbstract: Complex polynomial optimization problems arise from real-life applications including radar code design, MIMO beamforming, and quantum mechanics. In this paper, we study complex polynomial optimization models where the objective function takes one of the following three forms: (1) multilinear; (2) homogeneous polynomial; (3) symmetric conjugate form. On the constraint side, the decision variables belong to one of the following three sets: (1) the $$m$$ m -th roots of complex unity; (2) the complex unity; (3) the Euclidean sphere. We first discuss the multilinear objective function. Polynomial-time approximation algorithms are proposed for such problems with assured worst-case performance ratios, which depend only on the dimensions of the model. Then we introduce complex homogenous polynomial functions and establish key linkages between complex multilinear forms and the complex polynomial functions. Approximation algorithms for the above-mentioned complex polynomial optimization models with worst-case performance ratios are presented. Numerical results are reported to illustrate the effectiveness of the proposed approximation algorithms.","Title: On Convergence of the Maximum Block Improvement Method.\nYear: 2015\n\nAbstract: The MBI (maximum block improvement) method is a greedy approach to solving optimization problems where the decision variables can be grouped into a finite number of blocks. Assuming that optimizing over one block of variables while fixing all others is relatively easy, the MBI method updates the block of variables corresponding to the maximally improving block at each iteration, which is arguably a most natural and simple process to tackle block-structured problems with great potentials for engineering applications. In this paper we establish global and local linear convergence results for this method. The global convergence is established under the Lojasiewicz inequality assumption, while the local analysis invokes second-order assumptions. We study in particular the tensor optimization model with spherical constraints. Conditions for linear convergence of the famous power method for computing the maximum eigenvalue of a matrix follow in this framework as a special case. The condition is interpreted in various other forms for the rank-one tensor optimization model under spherical constraints. Numerical experiments are shown to support the convergence property of the MBI method.","Title: Inhomogeneous polynomial optimization over a convex set: An approximation approach.\nYear: 2015\n\nAbstract: In this paper, we consider computational methods for optimizing a multivariate inhomogeneous polynomial function over a general convex set. The focus is on the design and analysis of polynomial-time approximation algorithms. The methods are able to deal with optimization models with polynomial objective functions in any fixed degrees. In particular, we first study the problem of maximizing an inhomogeneous polynomial over the Euclidean ball. A polynomial-time approximation algorithm is proposed for this problem with an assured (relative) worst-case performance ratio, which is dependent only on the dimensions of the model. The method and approximation ratio are then generalized to optimize an inhomogeneous polynomial over the intersection of a finite number of co-centered ellipsoids. Furthermore, the constraint set is extended to a general convex compact set. Specifically, we propose a polynomial-time approximation algorithm with a (relative) worst-case performance ratio for polynomial optimization over some convex compact sets, e.g., a polytope. Finally, numerical results are reported, revealing good practical performance of the proposed algorithms for solving some randomly generated instances.","Title: Big data - a 21st century science Maginot Line? No-boundary thinking: shifting from the big data paradigm.\nYear: 2015\n\nAbstract: Whether your interests lie in scientific arenas, the corporate world, or in government, you have certainly heard the praises of big data: Big data will give you new insights, allow you to become more efficient, and/or will solve your problems. While big data has had some outstanding successes, many are now beginning to see that it is not the Silver Bullet that it has been touted to be. Here our main concern is the overall impact of big data; the current manifestation of big data is constructing a Maginot Line in science in the 21st century. Big data is not \"lots of data\" as a phenomena anymore; The big data paradigm is putting the spirit of the Maginot Line into lots of data. Big data overall is disconnecting researchers and science challenges. We propose No-Boundary Thinking (NBT), applying no-boundary thinking in problem defining to address science challenges.","Title: Probability Bounds for Polynomial Functions in Random Variables.\nYear: 2014\n\nAbstract: Random sampling is a simple but powerful method in statistics and in the design of randomized algorithms. In a typical application, random sampling can be applied to estimate an extreme value, say maximum, of a function f over a set S subset of R-n. To do so, one may select a simpler (even finite) subset S-0 subset of S, randomly take some samples over S-0 for a number of times, and pick the best sample. The hope is to find a good approximate solution with reasonable chance. This paper sets out to present a number of scenarios for f, S and S-0 where certain probability bounds can be established, leading to a quality assurance of the procedure. In our setting, f is a multivariate polynomial function. We prove that if f is a d-th order homogeneous polynomial in n variables and F is its corresponding super-symmetric tensor, and xi(i) (i = 1, 2, ..., n) are i.i.d. Bernoulli random variables taking 1 or -1 with equal probability, then Prob {f(xi(1), xi(2), ..., xi(n)) >= tau n(-d/2)parallel to F parallel to >= theta, where tau, theta > 0 are two universal constants and parallel to . parallel to(1) denotes the summation of the absolute values of all its entries. Several new inequalities concerning probabilities of the above nature are presented in this paper. Moreover, we show that the bounds are tight in most cases. Applications of our results in optimization are discussed as well.","Title: Moments Tensors, Hilbert's Identity, and k-wise Uncorrelated Random Variables.\nYear: 2014\n\nAbstract: In this paper, we introduce a notion to be called k-wise uncorrelated random variables, which is similar but not identical to the so-called k-wise independent random variables in the literature. We show how to construct k-wise uncorrelated random variables by a simple procedure. The constructed random variables can be applied, e.g., to express the quartic polynomial (x(T)Qx)(2), where Q is an n x n positive semidefinite matrix, by a sum of fourth powered polynomial terms, known as Hilbert's identity. By virtue of the proposed construction, the number of required terms is no more than 2n(4) + n. This implies that it is possible to find a (2n(4) + n)-point distribution whose fourth moments tensor is exactly the symmetrization of Q circle times Q. Moreover, we prove that the number of required fourth powered polynomial terms to express (x(T)Qx)(2) is at least n(n +1)/2. The result is applied to prove that computing the matrix 2 bar right arrow 4 norm is NP-hard. Extensions of the results to complex random variables are discussed as well.","Title: Characterizing Real-Valued Multivariate Complex Polynomials and Their Symmetric Tensor Representations.\nYear: 2016\n\nAbstract: In this paper we study multivariate polynomial functions in complex variables and their corresponding symmetric tensor representations. The focus is to find conditions under which such complex polynomials always take real values. We introduce the notion of symmetric conjugate forms and general conjugate forms, characterize the conditions for such complex polynomials to be real valued, and present their corresponding tensor representations. New notions of eigenvalues/eigenvectors for complex tensors are introduced, extending similar properties from the Hermitian matrices. Moreover, we study a property of the symmetric tensors, namely, the largest eigenvalue (in the absolute value sense) of a real symmetric tensor is equal to its largest singular value; the result is also known as Banach's theorem. We show that a similar result holds for the complex case as well. Finally, we discuss some applications of the new notion of eigenvalues/eigenvectors for the complex tensors.","Title: On implementation of a self-dual embedding method for convex programming\nYear: 2006\n\nAbstract: In this paper, we implement Zhang's method [Zhang, S., 2004, Journal of Global Optimization, 29, 479 - 496], which transforms a general convex optimization problem with smooth convex constraints into a convex conic optimization problem and then apply the techniques of self-dual embedding and central path-following for solving the resulting conic optimization model. A crucial advantage of the approach is that no initial solution is required and the method is particularly suitable when the feasibility status of the problem is unknown. In our implementation, we use a merit function approach proposed by Andersen and Ye [ Andersen, E. D. and Ye, Y., 1998, Computational Optimization and Applications, 10, 243 - 269] to determine the step-size along the search direction. We evaluate the efficiency of the proposed algorithm by observing its performance on some test problems, which include logarithmic functions, exponential functions and quadratic functions in the constraints. Furthermore, we consider in particular the geometric programming and L-p-programming problems. Numerical results of our algorithm on these classes of optimization problems are reported. We conclude that the algorithm is stable, efficient and easy-to-use in general. As the method allows the user to freely select the initial solution, it is natural to take advantage of this and apply the so-called warm-start strategy, whenever the data of a new problem is not too much different from a previously solved problem. This strategy turns out to be effective, according to our numerical experience.","Title: On the Global Linear Convergence of the ADMM with MultiBlock Variables.\nYear: 2015\n\nAbstract: The alternating direction method of multipliers (ADMM) has been widely used for solving structured convex optimization problems. In particular, the ADMM can solve convex programs that minimize the sum of N convex functions whose variables are linked by some linear constraints. While the convergence of the ADMM for N = 2 was well established in the literature, it remained an open problem for a long time whether the ADMM for N >= 3 is still convergent. Recently, it was shown in [Chen et al., Math. Program. (2014), DOI 10.1007/s10107-014-0826-5.] that without additional conditions the ADMM for N >= 3 generally fails to converge. In this paper, we show that under some easily verifiable and reasonable conditions the global linear convergence of the ADMM when N >= 3 can still be ensured, which is important since the ADMM is a popular method for solving large-scale multiblock optimization models and is known to perform very well in practice even when N >= 3. Our study aims to offer an explanation for this phenomenon.","Title: Local Linear Convergence of ISTA and FISTA on the LASSO Problem.\nYear: 2016\n\nAbstract: We use a model LASSO problem to analyze the convergence behavior of the ISTA and FISTA iterations, showing that both iterations satisfy local linear convergence rate bound when close enough to the solution. Using the observation that FISTA is an accelerated ISTA process, and a spectral analysis of the associated matrix operators, we show that FISTA's convergence rate can slow down as it proceeds, eventually becoming slower than ISTA. This observation leads to a proposed heuristic algorithm to take an ISTA step if it shows more progress compared to FISTA, as measured by the decrease in the objective function. We illustrate the results with some synthetic numerical examples.","Title: Improved Algorithms for Machine Allocation in Manufacturing Systems\nYear: 1994\n\nAbstract: In this paper we present two algorithms for a machine allocation problem occurring in manufacturing systems. For the two algorithms presented we prove worst-case performance ratios of 2 and 3/2, respectively. The machine allocation problem we consider is a general convex resource allocation problem, which makes the algorithms applicable to a variety of resource allocation problems. Numerical results are presented for two real-life manufacturing systems.","Title: Using duality to solve generalized fractional programming problems\nYear: 1996\n\nAbstract: In this paper we explore the relations between the standard dual problem of a convex generalized fractional programming problem and the “partial” dual problem proposed by Barros et al. (1994). Taking into account the similarities between these dual problems and using basic duality results we propose a new algorithm to directly solve the standard dual of a convex generalized fractional programming problem, and hence the original primal problem, if strong duality holds. This new algorithm works in a similar way as the algorithm proposed in Barros et al. (1994) to solve the “partial” dual problem. Although the convergence rates of both algorithms are similar, the new algorithm requires slightly more restrictive assumptions to ensure a superlinear convergence rate. An important characteristic of the new algorithm is that it extends to the nonlinear case the Dinkelbach-type algorithm of Crouzeix et al. (1985) applied to the standard dual problem of a generalized linear fractional program. Moreover, the general duality results derived for the nonlinear case, yield an alternative way to derive the standard dual of a generalized linear fractional program. The numerical results, in case of quadratic-linear ratios and linear constraints, show that solving the standard dual via the new algorithm is in most cases more efficient than applying directly the Dinkelbach-type algorithm to the original generalized fractional programming problem. However, the numerical results also indicate that solving the alternative dual (Barros et al., 1994) is in general more efficient than solving the standard dual.","Title: Convergence of Common Proximal Methods for L1-Regularized Least Squares.\nYear: 2015\n\nAbstract: We compare the convergence behavior of ADMM (alternating direction method of multipliers), [F]ISTA ([fast] iterative shrinkage and thresholding algorithm) and CD (coordinate descent) methods on the model l1-regularized least squares problem (aka LASSO). We use an eigenanalysis of the operators to compare their local convergence rates when close to the solution. We find that, when applicable, CD is often much faster than the other iterations, when close enough to the solution. When far from the solution, the spectral analysis implies that one can often get a sequence of iterates that appears to stagnate, but is actually taking small constant steps toward the solution. We also illustrate how the unaccelerated ISTA algorithm can sometimes be faster compared to FISTA when close enough to the solution.","Title: Radar code design with a Peak to average power Ratio constraint: A randomized approximate approach\nYear: 2011\n\nAbstract: This paper considers the problem of radar waveform design in the presence of colored Gaussian disturbance under a Peak to Average power Ratio (PAR) and an energy constraint. Firstly, we focus on the selection of the radar signal optimizing the Signal to Noise Power Ratio (SNR) for a given target Doppler frequency (Algorithm 1). Then, we devise its phase quantized version (Algorithm 2), which forces the waveform phase to lie within a finite alphabet. Both the problems are formulated in terms of NP-hard non-convex quadratic optimization programs; in order to solve them, we resort to Semidefinite Programming (SDP) relaxation and randomization techniques, providing provable-quality sub-optimal solutions with a polynomial time computational complexity. Finally, we analyze the performance in terms of detection capability and robustness with respect to Doppler shifts.","Title: Structured Nonconvex and Nonsmooth Optimization: Algorithms and Iteration Complexity Analysis.\nYear: 2019\n\nAbstract: Nonconvex and nonsmooth optimization problems are frequently encountered in much of statistics, business, science and engineering, but they are not yet widely recognized as a technology in the sense of scalability. A reason for this relatively low degree of popularity is the lack of a well developed system of theory and algorithms to support the applications, as is the case for its convex counterpart. This paper aims to take one step in the direction of disciplined nonconvex and nonsmooth optimization. In particular, we consider in this paper some constrained nonconvex optimization models in block decision variables, with or without coupled affine constraints. In the absence of coupled constraints, we show a sublinear rate of convergence to an \\(\\epsilon \\)-stationary solution in the form of variational inequality for a generalized conditional gradient method, where the convergence rate is dependent on the Hölderian continuity of the gradient of the smooth part of the objective. For the model with coupled affine constraints, we introduce corresponding \\(\\epsilon \\)-stationarity conditions, and apply two proximal-type variants of the ADMM to solve such a model, assuming the proximal ADMM updates can be implemented for all the block variables except for the last block, for which either a gradient step or a majorization–minimization step is implemented. We show an iteration complexity bound of \\(O(1/\\epsilon ^2)\\) to reach an \\(\\epsilon \\)-stationary solution for both algorithms. Moreover, we show that the same iteration complexity of a proximal BCD method follows immediately. Numerical results are provided to illustrate the efficacy of the proposed algorithms for tensor robust PCA and tensor sparse PCA problems.","Title: On New Classes of Nonnegative Symmetric Tensors.\nYear: 2017\n\nAbstract: In this paper we introduce three new classes of nonnegative forms (or equivalently, symmetric tensors) and their extensions. The newly identified nonnegative symmetric tensors constitute distinctive convex cones in the space of general symmetric tensors (order six or above). For the special case of quartic forms, they collapse into the set of convex quartic homogeneous polynomial functions. We discuss the properties and applications of the new classes of nonnegative symmetric tensors in the context of polynomial and tensor optimization. Numerical experiments for solving certain polynomial optimization models based on the new classes of nonnegative symmetric tensors are presented.","Title: A smoothing SQP framework for a class of composite $$L_q$$Lq minimization over polyhedron\nYear: 2016\n\nAbstract: The composite $$L_q~(0","Title: A Sparse Completely Positive Relaxation of the Modularity Maximization for Community Detection.\nYear: 2017\n\nAbstract: In this paper, we consider the community detection problem under either the stochastic block model (SBM) assumption or the degree-correlated SBM assumption. The modularity maximization formulation for the community detection problem is NP-hard in general. In this paper, we propose a sparse and low-rank completely positive relaxation for the modularity maximization problem, we then develop an efficient row-by-row (RBR)-type block coordinate descent algorithm to solve the relaxation and prove an O(1/root N) convergence rate to a stationary point, where N is the number of iterations. A fast rounding scheme is constructed to retrieve the community structure from a solution to the above relaxation. Nonasymptotic high probability bounds on the misclassification rate are established to justify our approach. We further develop an asynchronous parallel RBR algorithm to speed up the convergence. Extensive numerical experiments on both synthetic and real world networks show that the proposed approach enjoys advantages in both clustering accuracy and numerical efficiency. Our numerical results indicate that the newly proposed method is a competitive alternative for the community detection problem on sparse networks with over 50 million nodes.","Title: Highly Accurate Model For Prediction Of Lung Nodule Malignancy With Ct Scans\nYear: 2018\n\nAbstract: Computed tomography (CT) examinations are commonly used to predict lung nodule malignancy in patients, which are shown to improve noninvasive early diagnosis of lung cancer. It remains challenging for computational approaches to achieve performance comparable to experienced radiologists. Here we present NoduleX, a systematic approach to predict lung nodule malignancy from CT data, based on deep learning convolutional neural networks (CNN). For training and validation, we analyze >1000 lung nodules in images from the LIDC/IDRI cohort. All nodules were identified and classified by four experienced thoracic radiologists who participated in the LIDC project. NoduleX achieves high accuracy for nodule malignancy classification, with an AUC of similar to 0.99. This is commensurate with the analysis of the dataset by experienced radiologists. Our approach, NoduleX, provides an effective framework for highly accurate nodule malignancy prediction with the model trained on a large patient population. Our results are replicable with software available at http://bioinformatics.astate.edu/NoduleX.","Title: On the Information-Adaptive Variants of the ADMM: An Iteration Complexity Perspective.\nYear: 2018\n\nAbstract: Designing algorithms for an optimization model often amounts to maintaining a balance between the degree of information to request from the model on the one hand, and the computational speed to expect on the other hand. Naturally, the more information is available, the faster one can expect the algorithm to converge. The popular algorithm of ADMM demands that objective function is easy to optimize once the coupled constraints are shifted to the objective with multipliers. However, in many applications this assumption does not hold; instead, often only some noisy estimations of the gradient of the objective—or even only the objective itself—are available. This paper aims to bridge this gap. We present a suite of variants of the ADMM, where the trade-offs between the required information on the objective and the computational complexity are explicitly given. The new variants allow the method to be applicable on a much broader class of problems where only noisy estimations of the gradient or the function values are accessible, yet the flexibility is achieved without sacrificing the computational complexity bounds.","Title: Accelerated primal–dual proximal block coordinate updating methods for constrained convex optimization\nYear: 2018\n\nAbstract: Block coordinate update (BCU) methods enjoy low per-update computational complexity because every time only one or a few block variables would need to be updated among possibly a large number of blocks. They are also easily parallelized and thus have been particularly popular for solving problems involving large-scale dataset and/or variables. In this paper, we propose a primal---dual BCU method for solving linearly constrained convex program with multi-block variables. The method is an accelerated version of a primal---dual algorithm proposed by the authors, which applies randomization in selecting block variables to update and establishes an O(1 / t) convergence rate under convexity assumption. We show that the rate can be accelerated to $$O(1/t^2)$$O(1/t2) if the objective is strongly convex. In addition, if one block variable is independent of the others in the objective, we then show that the algorithm can be modified to achieve a linear rate of convergence. The numerical experiments show that the accelerated method performs stably with a single set of parameters while the original method needs to tune the parameters for different datasets in order to achieve a comparable level of performance.","Title: Low-M-Rank Tensor Completion and Robust Tensor PCA.\nYear: 2018\n\nAbstract: In this paper, we propose a new approach to solve low-rank tensor completion and robust tensor PCA. Our approach is based on some novel notion of (even-order) tensor ranks, to be called the M-rank, the symmetric M-rank, and the strongly symmetric M-rank. We discuss the connections between these new tensor ranks and the CP-rank and the symmetric CP-rank of an even-order tensor. We show that the M-r...","Title: An Optimal High-Order Tensor Method for Convex Optimization\nYear: 2019\n\nAbstract: This paper is concerned with finding an optimal algorithm for minimizing a composite convex objective function. The basic setting is that the objective is the sum of two convex functions: the first function is smooth with up to the dth-order derivative information available, and the second function is possibly nonsmooth, but its proximal tensor mappings can be computed approximately in an efficient manner. The problem is to find-in that setting-the best possible (optimal) iteration complexity for convex optimization. Along that line, for the smooth case (without the second nonsmooth part in the objective), Nesterov proposed an optimal algorithm for the first-order methods (d = 1) with iteration complexity O(1/k(2)), whereas high-order tensor algorithms (using up to general dth-order tensor information) with iteration complexity O(1/k(d+1)) were recently established. In this paper, we propose a new high-order tensor algorithm for the general composite case, with the iteration complexity of O(1/k((3d+1)/2)), which matches the lower bound for the dth-order methods as previously established and hence is optimal. Our approach is based on the accelerated hybrid proximal extragradient (A-HPE) framework proposed by Monteiro and Svaiter, where a bisection procedure is installed for each A-HPE iteration. At each bisection step, a proximal tensor subproblem is approximately solved, and the total number of bisection steps per A-HPE iteration is shown to be bounded by a logarithmic factor in the precision required.","Title: On lower iteration complexity bounds for the convex concave saddle point problems\nYear: 2022\n\nAbstract: In this paper, we study the lower iteration complexity bounds for finding the saddle point of a strongly convex and strongly concave saddle point problem: \n \n \n \n $$\\min _x\\max _yF(x,y)$$\n \n . We restrict the classes of algorithms in our investigation to be either pure first-order methods or methods using proximal mappings. For problems with gradient Lipschitz constants (\n \n \n \n $$L_x, L_y$$\n \n and \n \n \n \n $$L_{xy}$$\n \n ) and strong convexity/concavity constants (\n \n \n \n $$\\mu _x$$\n \n and \n \n \n \n $$\\mu _y$$\n \n ), the class of pure first-order algorithms with the linear span assumption is shown to have a lower iteration complexity bound of \n \n \n \n $$\\Omega \\,\\left( \\sqrt{\\frac{L_x}{\\mu _x}+\\frac{L_{xy}^2}{\\mu _x\\mu _y}+\\frac{L_y}{\\mu _y}}\\cdot \\ln \\left( \\frac{1}{\\epsilon }\\right) \\right) $$\n \n , where the term \n \n \n \n $$\\frac{L_{xy}^2}{\\mu _x\\mu _y}$$\n \n explains how the coupling influences the iteration complexity. Under several special parameter regimes, this lower bound has been achieved by corresponding optimal algorithms. However, whether or not the bound under the general parameter regime is optimal remains open. Additionally, for the special case of bilinear coupling problems, given the availability of certain proximal operators, a lower bound of \n \n \n \n $$\\Omega \\left( \\sqrt{\\frac{L_{xy}^2}{\\mu _x\\mu _y}}\\cdot \\ln (\\frac{1}{\\epsilon })\\right) $$\n \n is established under the linear span assumption, and optimal algorithms have already been developed in the literature. By exploiting the orthogonal invariance technique, we extend both lower bounds to the general pure first-order algorithm class and the proximal algorithm class without the linear span assumption. As an application, we apply proper scaling to the worst-case instances, and we derive the lower bounds for the general convex concave problems with \n \n \n \n $$\\mu _x = \\mu _y = 0$$\n \n . Several existing results in this case can be deduced from our results as special cases."],"string":"[\n \"Title: A unified adaptive co-identification framework for high-d expression data\\nYear: 2012\\n\\nAbstract: High-throughput techniques are producing large-scale high-dimensional (e.g., 4D with genes vs timepoints vs conditions vs tissues) genome-wide gene expression data. This induces increasing demands for effective methods for partitioning the data into biologically relevant groups. Current clustering and co-clustering approaches have limitations, which may be very time consuming and work for only low-dimensional expression datasets. In this work, we introduce a new notion of \\\"co-identification\\\", which allows systematical identification of genes participating different functional groups under different conditions or different development stages. The key contribution of our work is to build a unified computational framework of co-identification that enables clustering to be high-dimensional and adaptive. Our framework is based upon a generic optimization model and a general optimization method termed Maximum Block Improvement. Testing results on yeast and Arabidopsis expression data are presented to demonstrate high efficiency of our approach and its effectiveness.\",\n \"Title: Approximation algorithms for homogeneous polynomial optimization with quadratic constraints\\nYear: 2010\\n\\nAbstract: In this paper, we consider approximation algorithms for optimizing a generic multi-variate homogeneous polynomial function, subject to homogeneous quadratic constraints. Such optimization models have wide applications, e.g., in signal processing, magnetic resonance imaging (MRI), data training, approximation theory, and portfolio selection. Since polynomial functions are non-convex, the problems under consideration are all NP-hard in general. In this paper we shall focus on polynomial-time approximation algorithms. In particular, we first study optimization of a multi-linear tensor function over the Cartesian product of spheres. We shall propose approximation algorithms for such problem and derive worst-case performance ratios, which are shown to be dependent only on the dimensions of the model. The methods are then extended to optimize a generic multi-variate homogeneous polynomial function with spherical constraint. Likewise, approximation algorithms are proposed with provable approximation performance ratios. Furthermore, the constraint set is relaxed to be an intersection of co-centered ellipsoids; namely, we consider maximization of a homogeneous polynomial over the intersection of ellipsoids centered at the origin, and propose polynomial-time approximation algorithms with provable worst-case performance ratios. Numerical results are reported, illustrating the effectiveness of the approximation algorithms studied.\",\n \"Title: Multivariate Nonnegative Quadratic Mappings\\nYear: 2004\\n\\nAbstract: In this paper, we study several issues related to the characterization of specific classes of multivariate quadratic mappings that are nonnegative over a given domain, with nonnegativity defined by a prespecified conic order. In particular, we consider the set (cone) of nonnegative quadratic mappings, defined with respect to the positive semidefinite matrix cone, and study when it can be represented by linear matrix inequalities. We also discuss the applications of the results in robust optimization, especially the robust quadratic matrix inequalities and the robust linear programming models. In the latter application the implementational errors of the solution are taken into account, and the problem is formulated as a semidefinite program.\",\n \"Title: Sequencing jobs that require common resources on a single machine: A solvable case of the TSP\\nYear: 1998\\n\\nAbstract: In this paper a one-machine scheduling model is analyzed wheren different jobs are classified intoK groups depending on which additional resource they require. The change-over time from one job to another consists of the removal time or of the set-up time of the two jobs. It is sequence-dependent in the sense that the change-over time is determined by whether or not the two jobs belong to the same group. The objective is to minimize the makespan. This problem can be modeled as an asymmetric Traveling Salesman Problem (TSP) with a specially structured distance matrix. For this problem we give a polynomial time solution algorithm that runs in O(n logn) time. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.\",\n \"Title: Approximation Bounds for Quadratic Optimization with Homogeneous Quadratic Constraints\\nYear: 2007\\n\\nAbstract: We consider the NP-hard problem of finding a minimum norm vector in $n$-dimensional real or complex Euclidean space, subject to $m$ concave homogeneous quadratic constraints. We show that a semidefinite programming (SDP) relaxation for this nonconvex quadratically constrained quadratic program (QP) provides an $O(m^2)$ approximation in the real case and an $O(m)$ approximation in the complex case. Moreover, we show that these bounds are tight up to a constant factor. When the Hessian of each constraint function is of rank $1$ (namely, outer products of some given so-called steering vectors) and the phase spread of the entries of these steering vectors are bounded away from $\\\\pi/2$, we establish a certain “constant factor” approximation (depending on the phase spread but independent of $m$ and $n$) for both the SDP relaxation and a convex QP restriction of the original NP-hard problem. Finally, we consider a related problem of finding a maximum norm vector subject to $m$ convex homogeneous quadratic constraints. We show that an SDP relaxation for this nonconvex QP provides an $O(1/\\\\ln(m))$ approximation, which is analogous to a result of Nemirovski &etal; [Math. Program., 86 (1999), pp. 463-473] for the real case.\",\n \"Title: A New Self-Dual Embedding Method for Convex Programming\\nYear: 2004\\n\\nAbstract: In this paper we introduce a conic optimization formulation to solve constrained convex programming, and propose a self-dual embedding model for solving the resulting conic optimization problem. The primal and dual cones in this formulation are characterized by the original constraint functions and their corresponding conjugate functions respectively. Hence they are completely symmetric. This allows for a standard primal-dual path following approach for solving the embedded problem. Moreover, there are two immediate logarithmic barrier functions for the primal and dual cones. We show that these two logarithmic barrier functions are conjugate to each other. The explicit form of the conjugate functions are in fact not required to be known in the algorithm. An advantage of the new approach is that there is no need to assume an initial feasible solution to start with. To guarantee the polynomiality of the path-following procedure, we may apply the self-concordant barrier theory of Nesterov and Nemirovski. For this purpose, as one application, we prove that the barrier functions constructed this way are indeed self-concordant when the original constraint functions are convex and quadratic. We pose as an open question to find general conditions under which the constructed barrier functions are self-concordant.\",\n \"Title: Recursive approximation of the high dimensional max function\\nYear: 2005\\n\\nAbstract: This paper proposes a smoothing method for the general n-dimensional max function, based on a recursive extension of smoothing functions for the two-dimensional max function. A theoretical framework is introduced, and some applications are discussed. Finally, a numerical comparison with a well-known smoothing method is presented.\",\n \"Title: Tracking a Financial Benchmark Using a Few Assets\\nYear: 2006\\n\\nAbstract: We study the problem of tracking a financial benchmarka continuously compounded growth rate or a stock market indexby dynamically managing a portfolio consisting of a small number of traded stocks in the market. In either case, we formulate the tracking problem as an instance of the stochastic linear quadratic control (SLQ), involving indefinite cost matrices. As the SLQ formulation involves a discounted objective over an infinite horizon, we first address the issue of stabilizability. We then use semidefinite programming (SDP) as a computational tool to generate the optimal feedback control. We present numerical examples involving stocks traded at the Hong Kong and New York Stock Exchanges to illustrate the various features of the model and its performance.\",\n \"Title: Separated Continuous Conic Programming: Strong Duality and an Approximation Algorithm\\nYear: 2009\\n\\nAbstract: Motivated by recent applications in robust optimization and in sign-constrained linear-quadratic control, we study in this paper a new class of optimization problems called separated continuous conic programming (SCCP). Focusing on a symmetric primal-dual pair, we develop a strong duality theory for the SCCP. Our idea is to use discretization to connect the SCCP and its dual to two ordinary conic programs. We show if the latter are strongly feasible and with finite optimal values, a condition that is readily verifiable, then the strong duality holds for the SCCP. This approach also leads to a polynomial-time approximation algorithm that solves the SCCP to any required accuracy.\",\n \"Title: Tight Bounds for Some Risk Measures, with Applications to Robust Portfolio Selection\\nYear: 2011\\n\\nAbstract: In this paper we develop tight bounds on the expected values of several risk measures that are of interest to us. This work is motivated by the robust optimization models arising from portfolio selection problems. Indeed, the whole paper is centered around robust portfolio models and solutions. The basic setting is to find a portfolio that maximizes (respectively, minimizes) the expected utility (respectively, disutility) values in the midst of infinitely many possible ambiguous distributions of the investment returns fitting the given mean and variance estimations. First, we show that the single-stage portfolio selection problem within this framework, whenever the disutility function is in the form of lower partial moments (LPM), or conditional value-at-risk (CVaR), or value-at-risk (VaR), can be solved analytically. The results lead to the solutions for single-stage robust portfolio selection models. Furthermore, the results also lead to a multistage adjustable robust optimization (ARO) solution when the disutility function is the second-order LPM. Exploring beyond the confines of convex optimization, we also consider the so-called S-shaped value function, which plays a key role in the prospect theory of Kahneman and Tversky. The nonrobust version of the problem is shown to be NP-hard in general. However, we present an efficient procedure for solving the robust counterpart of the same portfolio selection problem. In this particular case, the consideration of the robustness actually helps to reduce the computational complexity. Finally, we consider the situation whereby we have some additional information about the chance that a quadratic function of the random distribution reaches a certain threshold. That information helps to further reduce the ambiguity in the robust model. We show that the robust optimization problem in that case can be solved by means of semidefinite programming (SDP), if no more than two additional chance inequalities are to be incorporated.\",\n \"Title: Complex Matrix Decomposition and Quadratic Programming\\nYear: 2007\\n\\nAbstract: This paper studies the possibilities of the linear matrix inequality characterization of the matrix cones formed by nonnegative complex Hermitian quadratic functions over specific domains in the complex space. In its real-case analog, such studies were conducted in Sturm and Zhang [Sturm, J. F., S. Zhang. 2003. On cones of nonnegative quadratic functions. Math. Oper. Res.28 246--267]. In this paper it is shown that stronger results can be obtained for the complex Hermitian case. In particular, we show that the matrix rank-one decomposition result of Sturm and Zhang [Sturm, J. F., S. Zhang. 2003. On cones of nonnegative quadratic functions. Math. Oper. Res.28 246--267] can be strengthened for the complex Hermitian matrices. As a consequence, it is possible to characterize several new matrix co-positive cones (over specific domains) by means of linear matrix inequality. As examples of the potential application of the new rank-one decomposition result, we present an upper bound on the lowest rank among all the optimal solutions for a standard complex semidefinite programming (SDP) problem, and offer alternative proofs for a result of Hausdorff [Hausdorff, F. 1919. Der Wertvorrat einer Bilinearform. Mathematische Zeitschrift3 314--316] and a result of Brickman [Brickman, L. 1961. On the field of values of a matrix. Proc. Amer. Math. Soc.12 61--66] on the joint numerical range.\",\n \"Title: Pivot rules for linear programming: A survey on recent theoretical developments\\nYear: 1993\\n\\nAbstract: The purpose of this paper is to discuss the various pivot rules of the simplex method and its variants that have been developed in the last two decades, starting from the appearance of the minimal index rule of Bland. We are mainly concerned with finiteness properties of simplex type pivot rules. Well known classical results concerning the simplex method are not considered in this survey, but the connection between the new pivot methods and the classical ones, if there is any, is discussed.\",\n \"Title: Global Error Bounds for Convex Conic Problems\\nYear: 2000\\n\\nAbstract: This paper aims at deriving and proving some Lipschitzian-type error bounds for convex conic problems in a simple way. First, it is shown that if the recession directions satisfy Slater's condition, then a global Lipschitzian-type error bound holds. Alternatively, if the feasible region is bounded, then the ordinary Slater condition guarantees a global Lipschitzian-type error bound. These can be considered as generalizations of previously known results for inequality systems, which also follow from general results by Bauschke and Borwein in [ SIAM Review, 38 (1996), pp. 367--426] and Bauschke, Borwein, and Li in a 1997 report. However, the proofs in the current paper are considerably simpler. Some of the results are generalized to the intersection of multiple shifted cones (with different shifts). Under Slater's condition alone, a global Lipschitzian-type error bound does not hold. It is shown, however, that such an error bound holds for a specific conic region. For linear systems we establish that the sharp constant involved in Hoffman's error bound is nothing but the condition number for linear programming as used by Vavasis and Ye in [ Math. Programming, 74 (1996), pp. 79--120].\",\n \"Title: No-boundary thinking in bioinformatics research.\\nYear: 2013\\n\\nAbstract: Currently there are definitions from many agencies and research societies defining \\\"bioinformatics\\\" as deriving knowledge from computational analysis of large volumes of biological and biomedical data. Should this be the bioinformatics research focus? We will discuss this issue in this review article. We would like to promote the idea of supporting human-infrastructure (HI) with no-boundary thinking (NT) in bioinformatics (HINT).\",\n \"Title: An O$(\\\\sqrtn L)$ Iteration Primal-dual Path-following Method, Based on Wide Neighborhoods and Large Updates, for Monotone LCP\\nYear: 2005\\n\\nAbstract: In this paper we propose a new class of primal-dual path-following interior point algorithms for solving monotone linear complementarity problems. At each iteration, the method would select a target on the central path with a large update from the current iterate, and then the Newton method is used to get the search directions, followed by adaptively choosing the step sizes, which are, e.g., the largest possible steps before leaving a neighborhood that is as wide as the given ${\\\\cal N}^-_{\\\\infty}$ neighborhood. The only deviation from the classical approach is that we treat the classical Newton direction as the sum of two other directions, corresponding to, respectively, the negative part and the positive part of the right-hand side. We show that if these two directions are equipped with different and appropriate step sizes, then the method enjoys the low iteration bound of $O(\\\\sqrt{n}\\\\log L)$, where $n$ is the dimension of the problem and $L=\\\\frac{(x^0)^Ts^0}{\\\\ep}$ with $\\\\ep$ the required precision and $(x^0,s^0)$ the initial interior solution. For a predictor-corrector variant of the method, we further prove that, besides the predictor steps, each corrector step also reduces the duality gap by a rate of $1-1/O(\\\\sqrt{n})$. Additionally, if the problem has a strict complementary solution, then the predictor steps converge Q-quadratically.\",\n \"Title: Complex Quadratic Optimization and Semidefinite Programming\\nYear: 2006\\n\\nAbstract: In this paper we study the approximation algorithms for a class of discrete quadratic optimization problems in the Hermitian complex form. A special case of the problem that we study corresponds to the max-3-cut model used in a recent paper of Goemans and Williamson J. Comput. System Sci., 68 (2004), pp. 442-470]. We first develop a closed-form formula to compute the probability of a complex-valued normally distributed bivariate random vector to be in a given angular region. This formula allows us to compute the expected value of a randomized (with a specific rounding rule) solution based on the optimal solution of the complex semidefinite programming relaxation problem. In particular, we present an $[m^2(1-\\\\cos\\\\frac{2\\\\pi}{m})/8\\\\pi]$-approximation algorithm, and then study the limit of that model, in which the problem remains NP-hard. We show that if the objective is to maximize a positive semidefinite Hermitian form, then the randomization-rounding procedure guarantees a worst-case performance ratio of $\\\\pi/4 \\\\approx 0.7854$, which is better than the ratio of $2/\\\\pi \\\\approx 0.6366$ for its counterpart in the real case due to Nesterov. Furthermore, if the objective matrix is real-valued positive semidefinite with nonpositive off-diagonal elements, then the performance ratio improves to 0.9349.\",\n \"Title: Robust Multicast Beamforming for Spectrum Sharing-Based Cognitive Radios\\nYear: 2012\\n\\nAbstract: We consider a robust downlink beamforming optimization problem for secondary multicast transmission in a multiple-input multiple-output (MIMO) spectrum sharing cognitive radio (CR) network. The minimization of transmit power is formulated subject to both quality-of-service (QoS) constraints on the secondary receivers and interference temperature constraints on the primary users, under the assumption of imperfect channel state information (CSI). The problem is a nonconvex quadratically constrained quadratic program (QCQP), and in general it is hard to achieve the global optimality. As a compromise, we present two randomized approximation algorithms for the problem via convex optimization techniques. Apart from the general setting of the robust beamforming problem, we identify one interesting special case, the robust problem of which can be solved efficiently. Simulation results are presented to demonstrate the performance gains of the proposed algorithms over an existing robust design.\",\n \"Title: Maximum Block Improvement and Polynomial Optimization\\nYear: 2012\\n\\nAbstract: In this paper we propose an efficient method for solving the spherically constrained homogeneous polynomial optimization problem. The new approach has the following three main ingredients. First, we establish a block coordinate descent type search method for nonlinear optimization, with the novelty being that we accept only a block update that achieves the maximum improvement, hence the name of our new search method: maximum block improvement (MBI). Convergence of the sequence produced by the MBI method to a stationary point is proved. Second, we establish that maximizing a homogeneous polynomial over a sphere is equivalent to its tensor relaxation problem; thus we can maximize a homogeneous polynomial function over a sphere by its tensor relaxation via the MBI approach. Third, we propose a scheme to reach a KKT point of the polynomial optimization, provided that a stationary solution for the relaxed tensor problem is available. Numerical experiments have shown that our new method works very efficiently: for a majority of the test instances that we have experimented with, the method finds the global optimal solution at a low computational cost.\",\n \"Title: A new framework for co-clustering of gene expression data\\nYear: 2011\\n\\nAbstract: A new framework is proposed to study the co-clustering of gene expression data. This framework is based on a generic tensor optimization model and an optimization method termed Maximum Block Improvement (MBI) recently developed in [3]. Not only can this framework be applied for co-clustering gene expression data with genes expressed at different conditions represented in 2D matrices, but it can also be readily applied for co-clustering more complex high-dimensional gene expression data with genes expressed at different tissues, different development stages, different time points, different stimulations, etc. Moreover, the new framework is so flexible that it poses no difficulty at all to incorporate a variety of clustering quality measurements. In this paper, we demonstrate the effectiveness of this new approach by providing the details of one specific implementation of the algorithm, and presenting the experimental testing on microarray gene expression datasets. Our results show that the new algorithm is very efficient and it performs well for identifying patterns in gene expression datasets.\",\n \"Title: Bounding Probability of Small Deviation: A Fourth Moment Approach\\nYear: 2010\\n\\nAbstract: In this paper we study the problem of upper bounding the probability that a random variable is above its expected value by a small amount (relative to the expected value), by means of the second and the fourth (central) moments of the random variable. In this particular context, many classical inequalities yield only trivial bounds. We obtain tight upper bounds by studying the primal-dual moments-generating conic optimization problems. As an application, we demonstrate that given the new probability bounds, a substantial sharpening and simplification of a recent result and its analysis by Feige (see Feige, U. 2006. On sums of independent random variables with unbounded variances, and estimating the average degree in a graph. SIAM J. Comput.35 964--984) can be obtained; also, these bounds lead to new properties of the distribution of the cut values for the max-cut problem. We expect the new probability bounds to be useful in many other applications.\",\n \"Title: On a Wide Region of Centers and Primal-Dual Interior Point Algorithms for Linear Programming\\nYear: 1997\\n\\nAbstract: In the adaptive step primal-dual interior point method for linear programming, polynomial algorithms are obtained by computing Newton directions towards targets on the central path, and restricting the iterates to a neighborhood of this central path. In this paper, the adaptive step methodology is extended, by considering targets in a certain central region, which contains the usual central path, and subsequently generating iterates in a neighborhood of this region. The size of the central region can vary from the central path to the whole feasible region by choosing a certain parameter. An O√nL iteration bound is obtained under mild conditions on the choice of the target points. In particular, we leave plenty of room for experimentation with search directions. The practical performance of the new primal-dual interior point method is measured on part of the Netlib test set for various sizes of the central region.\",\n \"Title: An interior point method, based on rank-1 updates, for linear programming\\nYear: 1998\\n\\nAbstract: We propose a polynomial time primal—dual potential reduction algorithm for linear programming. The algorithm generates sequencesdk andvk rather than a primal—dual interior point (x k ,s k ), where\\\\(d_i^k = \\\\sqrt {{{x_i^k } \\\\mathord{\\\\left/ {\\\\vphantom {{x_i^k } {s_i^k }}} \\\\right. \\\\kern-\\\\nulldelimiterspace} {s_i^k }}} \\\\) and\\\\(v_i^k = \\\\sqrt {x_i^k s_i^k }\\\\) fori = 1, 2,⋯,n. Only one element ofdk is changed in each iteration, so that the work per iteration is bounded by O(mn) using rank-1 updating techniques. The usual primal—dual iteratesxk andsk are not needed explicitly in the algorithm, whereasdk andvk are iterated so that the interior primal—dual solutions can always be recovered by aforementioned relations between (xk, sk) and (dk, vk) with improving primal—dual potential function values. Moreover, no approximation ofdk is needed in the computation of projection directions. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.\",\n \"Title: Stochastic Linear-Quadratic Control via Primal-Dual Semidefinite Programming.\\nYear: 2004\\n\\nAbstract: We study stochastic linear-quadratic (LQ) optimal control problems over an infinite time horizon, allowing the cost matrices to be indefinite. We develop a systematic approach based on semidefinite programming (SDP). A central issue is the stability of the feedback control. We show that this can be effectively examined through the complementary duality of the SDP. Furthermore, we establish several implication relations among the SDP complementary duality, the (generalized) Riccati equation, and the optimality of the LQ control problem. Based on these relations, we propose a numerical procedure that provides a thorough treatment of the LQ control problem via primal-dual SDP: it identifies a stabilizing feedback control that is optimal or determines that the problem possesses no optimal solution. For the latter case, we develop an E-approximation scheme that is asymptotically optimal.\",\n \"Title: A $${\\\\mathsf{D}}$$-induced duality and its applications\\nYear: 2008\\n\\nAbstract: This paper attempts to extend the notion of duality for convex cones, by basing it on a prescribed conic ordering and a fixed\\n bilinear mapping. This is an extension of the standard definition of dual cones, in the sense that the nonnegativity of the inner-product is replaced by a pre-specified conic ordering, defined by a convex cone $${\\\\mathsf{D}}$$ , and the inner-product itself is replaced by a general multi-dimensional bilinear mapping. This new type of duality is termed\\n the $${\\\\mathsf{D}}$$-induced duality in the paper. We further introduce the notion of $${\\\\mathsf{D}}$$-induced polar sets within the same framework, which can be viewed as a generalization of the $${\\\\mathsf{D}}$$-induced dual cones and is convenient to use for some practical applications. Properties of the extended duality, including\\n the extended bi-polar theorem, are proven. Furthermore, attention is paid to the computation and approximation of the $${\\\\mathsf{D}}$$ -induced dual objects. We discuss, as examples, applications of the newly introduced $${\\\\mathsf{D}}$$-induced duality concepts in robust conic optimization and the duality theory for multi-objective conic optimization.\",\n \"Title: On the long-step path-following method for semidefinite programming\\nYear: 1998\\n\\nAbstract: It has been shown in various recent research reports that the analysis of short-step primal-dual path following algorithms for linear programming can be nicely generalized to semidefinite programming. However, the analysis of long-step path-following algorithms for semidefinite programming appeared to be less straightforward. For such an algorithm, Monteiro (1997) obtained an O(n^1^.^5log(1/@e)) iteration bound for obtaining an @e-optimal solution, where n is the order of the semidefinite decision variable. In this paper, we propose to use a different search direction, viz. the so-called V-space direction. It is shown that this modification reduces the iteration complexity to O(nlog(1/@e)). Independently, Monteiro and Y. Zhang obtained a similar result using Nesterov-Todd directions.\",\n \"Title: Design of phase codes for radar performance optimization with a similarity constraint\\nYear: 2009\\n\\nAbstract: This paper deals with the design of coded waveforms which optimize radar performances in the presence of colored Gaussian disturbance. We focus on the class of phase coded pulse trains and determine the radar code which approximately maximizes the detection performance under a similarity constraint with a prefixed radar code. This is tantamount to forcing a similarity between the ambiguity functions of the devised waveform and of the pulse train encoded with the prefixed sequence. We consider the cases of both continuous and finite phase alphabet, and formulate the code design in terms of a nonconvex, NP-hard quadratic optimization problem. In order to approximate the optimal solutions, we propose techniques (with polynomial computational complexity) based on the method of semidefinite program (SDP) relaxation and randomization. Moreover, we also derive approximation bounds yielding a \\\"measure of goodness\\\" of the devised algorithms. At the analysis stage, we assess the performance of the new encoding techniques both in terms of detection performance and ambiguity function, under different choices for the similarity parameter. We also show that the new algorithms achieve an accurate approximation of the optimal solution with a modest number of randomizations.\",\n \"Title: Foreword: Special issue on large-scale nonlinear and semidefinite programming.\\nYear: 2007\\n\\nAbstract: Without Abstract\",\n \"Title: Sparse solutions to random standard quadratic optimization problems.\\nYear: 2013\\n\\nAbstract: The standard quadratic optimization problem (StQP) refers to the problem of minimizing a quadratic form over the standard simplex. Such a problem arises from numerous applications and is known to be NP-hard. In this paper we focus on a special scenario of the StQP where all the elements of the data matrix Q are independently identically distributed and follow a certain distribution such as uniform or exponential distribution. We show that the probability that such a random StQP has a global optimal solution with k nonzero elements decays exponentially in k. Numerical evaluation of our theoretical finding is discussed as well.\",\n \"Title: Strong Duality for the CDT Subproblem: A Necessary and Sufficient Condition\\nYear: 2009\\n\\nAbstract: In this paper, we consider the problem of minimizing a nonconvex quadratic function, subject to two quadratic inequality constraints. As an application, such a quadratic program plays an important role in the trust region method for nonlinear optimization; such a problem is known as the Celis, Dennis, and Tapia (CDT) subproblem in the literature. The Lagrangian dual of the CDT subproblem is a semidefinite program (SDP), hence convex and solvable. However, a positive duality gap may exist between the CDT subproblem and its Lagrangian dual because the CDT subproblem itself is nonconvex. In this paper, we present a necessary and sufficient condition to characterize when the CDT subproblem and its Lagrangian dual admits no duality gap (i.e., the strong duality holds). This necessary and sufficient condition is easy verifiable and involves only one (any) optimal solution of the SDP relaxation for the CDT subproblem. Moreover, the condition reveals that it is actually rare to render a positive duality gap for the CDT subproblems in general. Moreover, if the strong duality holds, then an optimal solution for the CDT problem can be retrieved from an optimal solution of the SDP relaxation, by means of a matrix rank-one decomposition procedure. The same analysis is extended to the framework where the necessary and sufficient condition is presented in terms of the Lagrangian multipliers at a KKT point. Furthermore, we show that the condition is numerically easy to work with approximatively.\",\n \"Title: On weighted centers for semidefinite programming\\nYear: 2000\\n\\nAbstract: In this paper, we generalize the notion of weighted centers to semidefinite programming. Our analysis fits in the v-space framework, which is purely based on the symmetric primal–dual transformation and does not make use of barriers. Existence and scale invariance properties are proven for the weighted centers. Relations with other primal–dual maps are discussed.\",\n \"Title: Robust secondary multicast transmit beamforming for cognitive radio networks under imperfect channel state information.\\nYear: 2011\\n\\nAbstract: Consider a robust downlink beamforming optimization problem for secondary multicast transmission in a multiple-input multiple-output (MIMO) spectrum sharing cognitive radio (CR) network. The minimization problem of transmit power is formulated subject to both the quality-of-service (QoS) constraints on the secondary receivers and the interference temperature constraints on the primary users, under the assumption of imperfect channel state information (CSI). The problem is non-convex quadratically constrained quadratic program (QCQP), and it is hard to achieve the global optimality. As a compromise, we present a randomized approximation algorithm for the problem via convex optimization techniques. In particular, we point out that the robust beamforming problem is efficiently solvable when the number of primary and secondary links in the CR network is not larger than three. Simulation results are presented to demonstrate the performance gains of the proposed algorithm over an existing robust design.\",\n \"Title: Duality gap estimation and polynomial time approximation for optimal spectrum management\\nYear: 2009\\n\\nAbstract: Consider a communication system whereby multiple users share a common frequency band and must choose their transmit power spectra jointly in response to physical channel conditions including the effects of interference. The goal of the users is to maximize a system-wide utility function (e.g., weighted sum-rate of all users), subject to individual power constraints. A popular approach to solve the discretized version of this nonconvex problem is by Lagrangian dual relaxation. Unfortunately the discretized spectrum management problem is NP-hard and its Lagrangian dual is in general not equivalent to the primal formulation due to a positive duality gap. In this paper, we use a convexity result of Lyapunov to estimate the size of duality gap for the discretized spectrum management problem and show that the duality gap vanishes asymptotically at the rate O(1/√N), where N is the size of the uniform discretization of the shared spectrum. If the channels are frequency flat, the duality gap estimate improves to O(1/N). Moreover, when restricted to the FDMA spectrum sharing strategies, we show that the Lagrangian dual relaxation, combined with a linear programming scheme, can generate an ε-optimal solution for the continuous formulation of the spectrum management problem in polynomial time for any ε O.\",\n \"Title: Quadratic maximization and semidefinite relaxation\\nYear: 2000\\n\\nAbstract: . In this paper we study a class of quadratic maximization problems and their semidefinite programming (SDP) relaxation. For\\n a special subclass of the problems we show that the SDP relaxation provides an exact optimal solution. Another subclass, which\\n is ??-hard, guarantees that the SDP relaxation yields an approximate solution with a worst-case performance ratio of 0.87856....\\n This is a generalization of the well-known result of Goemans and Williamson for the maximum-cut problem. Finally, we discuss\\n extensions of these results in the presence of a certain type of sign restrictions.\",\n \"Title: Semidefinite Relaxation Bounds for Indefinite Homogeneous Quadratic Optimization\\nYear: 2008\\n\\nAbstract: This paper studies the relationship between the optimal value of a homogeneous quadratic optimization problem and its semidefinite programming (SDP) relaxation. We consider two quadratic optimization models: (1) $\\\\min \\\\{ x^* C x \\\\mid x^* A_k x \\\\ge 1, k=0,1,\\\\ldots,m, x\\\\in\\\\mathbb{F}^n\\\\}$ and (2) $\\\\max \\\\{ x^* C x \\\\mid x^* A_k x \\\\le 1, k=0,1,\\\\ldots,m, x\\\\in\\\\mathbb{F}^n\\\\}$, where $\\\\mathbb{F}$ is either the real field $\\\\mathbb{R}$ or the complex field $\\\\mathbb{C}$, and $A_k,C$ are symmetric matrices. For the minimization model (1), we prove that if the matrix $C$ and all but one of the $A_k$'s are positive semidefinite, then the ratio between the optimal value of (1) and its SDP relaxation is upper bounded by $O(m^2)$ when $\\\\mathbb{F}=\\\\mathbb{R}$, and by $O(m)$ when $\\\\mathbb{F}=\\\\mathbb{C}$. Moreover, when two or more of the $A_k$'s are indefinite, this ratio can be arbitrarily large. For the maximization model (2), we show that if $C$ and at most one of the $A_k$'s are indefinite while other $A_k$'s are positive semidefinite, then the ratio between the optimal value of (2) and its SDP relaxation is bounded from below by $O(1/\\\\log m)$ for both the real and the complex case. This result improves the bound based on the so-called approximate S-Lemma of Ben-Tal, Nemirovski, and Roos [SIAM J. Optim., 13 (2002), pp. 535-560]. When two or more of the $A_k$'s in (2) are indefinite, we derive a general bound in terms of the problem data and the SDP solution. For both optimization models, we present examples to show that the derived approximation bounds are essentially tight.\",\n \"Title: New Results on Quadratic Minimization\\nYear: 2003\\n\\nAbstract: In this paper we present several new results on minimizing an indefinite quadratic function under quadratic/linear constraints. The emphasis is placed on the case in which the constraints are two quadratic inequalities. This formulation is termed the extended trust region subproblem in this paper, to distinguish it from the ordinary trust region subproblem, in which the constraint is a single ellipsoid. The computational complexity of the extended trust region subproblem in general is still unknown. In this paper we consider several interesting cases related to this problem and show that for those cases the corresponding semidefinite programming relaxation admits no gap with the true optimal value, and consequently we obtain polynomial-time procedures for solving those special cases of quadratic optimization. For the extended trust region subproblem itself, we introduce a parameterized problem and prove the existence of a trajectory that will lead to an optimal solution. Combining this with a result obtained in the first part of the paper, we propose a polynomial-time solution procedure for the extended trust region subproblem arising from solving nonlinear programs with a single equality constraint.\",\n \"Title: New results on Hermitian matrix rank-one decomposition\\nYear: 2011\\n\\nAbstract: In this paper, we present several new rank-one decomposition theorems for Hermitian positive semidefinite matrices, which generalize our previous results in Huang and Zhang (Math Oper Res 32(3):758–768, 2007), Ai and Zhang (SIAM J Optim 19(4):1735–1756, 2009). The new matrix rank-one decomposition theorems appear to have wide applications in theory as well as in practice. On the theoretical side, for example, we show how to further extend some of the classical results including a lemma due to Yuan (Math Program 47:53–63, 1990), the classical results on the convexity of the joint numerical ranges (Pang and Zhang in Unpublished Manuscript, 2004; Au-Yeung and Poon in Southeast Asian Bull Math 3:85–92, 1979), and the so-called Finsler’s lemma (Bohnenblust in Unpublished Manuscript; Au-Yeung and Poon in Southeast Asian Bull Math 3:85–92, 1979). On the practical side, we show that the new results can be applied to solve two typical problems in signal processing and communication: one for radar code optimization and the other for robust beamforming. The new matrix decomposition theorems are proven by construction in this paper, and we demonstrate that the constructive procedures can be implemented efficiently, stably, and accurately. The URL of our Matlab programs is given in this paper. We strongly believe that the new decomposition procedures, as a means to solve non-convex quadratic optimization with a few quadratic constraints, are useful for many other potential engineering applications.\",\n \"Title: On the Low Rank Solutions for Linear Matrix Inequalities\\nYear: 2008\\n\\nAbstract: In this paper we present a polynomial-time procedure to find a low-rank solution for a system of linear matrix inequalities (LMI). The existence of such a low-rank solution was shown in the work of Au-Yeung and Poon and the work of Barvinok. In the approach of Au-Yeung and Poon an earlier unpublished manuscript of Bohnenblust played an essential role. Both proofs in the work of Au-Yeung and Poon and that of Barvinok are nonconstructive in nature. The aim of this paper is to provide a polynomial-time constructive procedure to find such a low-rank solution approximatively. Extensions of our new results and their relations to some of the known results in the literature are discussed.\",\n \"Title: On distributional robust probability functions and their computations.\\nYear: 2014\\n\\nAbstract: •Introduce “distributional robust probability function” with input moments.•Revisit worst case VaR-portfolio with a new concept (i.e. the existence of zeta).•Introduce new computational methods for joint probability moment bounds.•The new method is exact, while only approximation is available currently.•Three applications are introduced for risk management purposes.\",\n \"Title: Robust portfolio selection based on a multi-stage scenario tree\\nYear: 2008\\n\\nAbstract: The aim of this paper is to apply the concept of robust optimization introduced by Bel-Tal and Nemirovski to the portfolio selection problems based on multi-stage scenario trees. The objective of our portfolio selection is to maximize an expected utility function value (or equivalently, to minimize an expected disutility function value) as in a classical stochastic programming problem, except that we allow for ambiguities to exist in the probability distributions along the scenario tree. We show that such a problem can be formulated as a finite convex program in the conic form, on which general convex optimization techniques can be applied. In particular, if there is no short-selling, and the disutility function takes the form of semi-variance downside risk, and all the parameter ambiguity sets are ellipsoidal, then the problem becomes a second order cone program, thus tractable. We use SeDuMi to solve the resulting robust portfolio selection problem, and the simulation results show that the robust consideration helps to reduce the variability of the optimal values caused by the parameter ambiguity.\",\n \"Title: The Role of Robust Optimization in Single-Leg Airline Revenue Management\\nYear: 2009\\n\\nAbstract: In this paper, we introduce robust versions of the classical static and dynamic single-leg seat allocation models. These robust models take into account the inaccurate estimates of the underlying probability distributions. As observed by simulation experiments, it turns out that for these robust versions the variability compared to their classical counterparts is considerably reduced with a negligible decrease in average revenue.\",\n \"Title: Code Design to Optimize Radar Detection Performance Under Accuracy and Similarity Constraints\\nYear: 2008\\n\\nAbstract: This paper deals with the design of coded waveforms which optimize radar performances in the presence of colored Gaussian disturbance. We focus on the class of linearly coded pulse trains and determine the optimum radar code according to the following criterion: maximization of the detection performance under a control on the region of achievable Doppler estimation accuracies, and imposing a similarity constraint with a prefixed radar code. This last constraint is tantamount to requiring a similarity between the ambiguity functions of the devised waveform and of the pulse train encoded with the prefixed sequence. The resulting optimization problem is nonconvex and quadratic. In order to solve it, we propose a technique (with polynomial computational complexity) based on the relaxation of the original problem into a semidefinite program. Thus, the best code is determined through a rank-one decomposition of an optimal solution of the relaxed problem. At the analysis stage, we assess the performance of the new encoding technique in terms of detection performance, region of achievable Doppler estimation accuracies, and ambiguity function.\",\n \"Title: On cones of nonnegative quadratic functions\\nYear: 2003\\n\\nAbstract: We derive linear matrix inequality (LMI) characterizations and dual decomposition algorithms for certain matrix cones which are generated by a given set using generalized co-positivity. These matrix cones are in fact cones of nonconvex quadratic functions that are nonnegative on a certain domain. As a domain, we consider for instance the intersection of a (upper) level-set of a quadratic function and a half-plane. Consequently, we arrive at a generalization of Yakubovich's S-procedure result. Although the primary concern of this paper is to characterize the matrix cones by LMIs, we show, as an application of our results, that optimizing a general quadratic function over the intersection of an ellipsoid and a half-plane can be formulated as semidefinite programming (SDP), thus proving the polynomiality of this class of optimization problems, which arise, e.g., from the application of the trust region method for nonlinear programming. Other applications are in control theory and robust optimization.\",\n \"Title: A Semidefinite Relaxation Scheme for Multivariate Quartic Polynomial Optimization with Quadratic Constraints\\nYear: 2010\\n\\nAbstract: We present a general semidefinite relaxation scheme for general $n$-variate quartic polynomial optimization under homogeneous quadratic constraints. Unlike the existing sum-of-squares approach which relaxes the quartic optimization problems to a sequence of (typically large) linear semidefinite programs (SDP), our relaxation scheme leads to a (possibly nonconvex) quadratic optimization problem with linear constraints over the semidefinite matrix cone in $\\\\mathbb{R}^{n\\\\times n}$. It is shown that each $\\\\alpha$-factor approximate solution of the relaxed quadratic SDP can be used to generate in randomized polynomial time an $O(\\\\alpha)$-factor approximate solution for the original quartic optimization problem, where the constant in $O(\\\\cdot)$ depends only on problem dimension. In the case where only one positive definite quadratic constraint is present in the quartic optimization problem, we present a randomized polynomial time approximation algorithm which can provide a guaranteed relative approximation ratio of $(1-O(n^{-2}))$.\",\n \"Title: Low-complexity algorithms for sequencing jobs with a fixed number of job-classes\\nYear: 1996\\n\\nAbstract: In this paper we consider the problem of scheduling n jobs such that makespan is minimized. It is assumed that the jobs can be divided into K job-classes and that the change-over time between two consecutive jobs depends on the job-classes to which the two jobs belong. In this setting, we discuss the one machine scheduling problem with arbitrary processing times and the parallel machines scheduling problem with identical processing times. In both cases it is assumed that the number of job-classes K is fixed. By using an appropriate integer programming formulation with a fixed number of variables and constraints, it is shown that these two problems are solvable in polynomial time. For the one machine scheduling case it is shown that the complexity of our algorithm is linear in the number of jobs n . Moreover, if the problem is encoded according to the high multiplicity model of Hochbaum and Shamir, the time complexity of the algorithm is shown to be a polynomial in log n . In the parallel machine scheduling case, it is shown that if the number of machines is fixed the same results hold.\",\n \"Title: Fractional QCQP With Applications in ML Steering Direction Estimation for Radar Detection\\nYear: 2011\\n\\nAbstract: This paper deals with the problem of estimating the steering direction of a signal, embedded in Gaussian disturbance, under a general quadratic inequality constraint, representing the uncertainty region of the steering. We resort to the maximum likelihood (ML) criterion and focus on two scenarios. The former assumes that the complex amplitude of the useful signal component fluctuates from snapshot to snapshot. The latter supposes that the useful signal keeps a constant amplitude within all the snapshots. We prove that the ML criterion leads in both cases to a fractional quadratically constrained quadratic problem (QCQP). In order to solve it, we first relax the problem into a constrained fractional semidefinite programming (SDP) problem which is shown equivalent, via the Charnes-Cooper transformation, to an SDP problem. Then, exploiting a suitable rank-one decomposition, we show that the SDP relaxation is tight and give a procedure to construct (in polynomial time) an optimal solution of the original problem from an optimal solution of the fractional SDP. We also assess the quality of the derived estimator through a comparison between its performance and the constrained Cramer Rao lower Bound (CRB). Finally, we give two applications of the proposed theoretical framework in the context of radar detection.\",\n \"Title: Lorentz-Positive Maps and Quadratic Matrix Inequalities With Applications to Robust MISO Transmit Beamforming\\nYear: 2013\\n\\nAbstract: Consider a unicast downlink beamforming optimization problem with robust signal-to-interference-plus-noise ratio constraints to account for imperfect channel state information at the base station in a multiple-input single-output (MISO) communication system. The convexity of this robust beamforming problem remains unknown. A slightly conservative version of the robust beamforming problem is thus studied herein as a compromise. It is in the form of a semi-infinite second-order cone program (SOCP) and, more importantly, it possesses an equivalent and explicit convex reformulation, due to a linear matrix inequality (LMI) description of the cone of Lorentz-positive maps. Hence, the conservative robust beamforming problem can be efficiently solved by an optimization solver. Additional robust shaping constraints can also be easily handled to control the amount of interference generated on other co-existing users such as in cognitive radio systems.\",\n \"Title: Lorentz-positive mapswith applications to robust MISO downlink beamforming\\nYear: 2012\\n\\nAbstract: Consider a unicast downlink beamforming optimization problem with robust signal-to-interference-plus-noise ratio constraints to account for non-perfect channel state information at the base station. The convexity of the robust beamforming problem remains unknown. A slightly conservative version of the robust beamforming problem is thus studied herein as a compromise. It is in the form of a semi-infinite second-order cone program (SOCP), and more importantly, it possesses an equivalent and explicit convex reformulation, due to an linear matrix inequality description of the cone of Lorentz-positive maps. Hence the robust beamforming problem can be efficiently solved by an optimization solver. The simulation results show that the conservativeness of the robust form of semi-infinite SOCP is appropriate in terms of problem feasibility rate and the average transmission power.\",\n \"Title: Optimal Linear Decentralized Estimation In A Bandwidth Constrained Sensor Network\\nYear: 2005\\n\\nAbstract: Consider a bandwidth constrained sensor network in which a set of distributed sensors and a fusion center (FC) collaborate to estimate an unknown vector. Due to power and cost limitations, each sensor must compress its data in order to minimize the amount of information that need to be communicated to the FC. In this paper, we consider the design of a linear decentralized estimation scheme (DES) whereby each sensor transmits over a noisy channel to the FC a fixed number of real-valued messages which are linear functions of its observations, while the FC linearly combines the received messages to estimate the unknown parameter vector. Assuming each sensor collects data according to a local linear model, we propose to design optimal linear message functions and linear fusion function according to the minimum mean squared error (NMSE) criterion. We show that the resulting design problem is nonconvex and NP-hard in general, and identify two special cases for which the optimal linear DES design problem can be efficiently solved either in closed form or by Semi-definite programming (SDP).\",\n \"Title: Stochastic Linear-Quadratic Control via Semidefinite Programming\\nYear: 2001\\n\\nAbstract: We study stochastic linear-quadratic (LQ) optimal control problems over an infinite time horizon, allowing the cost matrices to be indefinite. We develop a systematic approach based on semidefinite programming (SDP). A central issue is the stability of the feedback control; and we show this can be effectively examined through the complementary duality of the SDP. Furthermore, we establish several implication relations among the SDP complementary duality, the (generalized) Riccati equation, and the optimality of the LQ control problem. Based on these relations, we propose a numerical procedure that provides a thorough treatment of the LQ control problem via primal-dual SDP: it identifies a stabilizing feedback control that is optimal or determines that the problem possesses no optimal solution. For the latter case, we develop an $\\\\epsilon$-approximation scheme that is asymptotically optimal.\",\n \"Title: A Primal-Dual Decomposition Algorithm for Multistage Stochastic Convex Programming\\nYear: 2005\\n\\nAbstract: This paper presents a new and high performance solution method for multistage stochastic convex programming. Stochastic programming is a quantitative tool developed in the field of optimization to cope with the problem of decision-making under uncertainty. Among others, stochastic programming has found many applications in finance, such as asset-liability and bond-portfolio management. However, many stochastic programming applications still remain computationally intractable because of their overwhelming dimensionality. In this paper we propose a new decomposition algorithm for multistage stochastic programming with a convex objective and stochastic recourse matrices, based on the path-following interior point method combined with the homogeneous self-dual embedding technique. Our preliminary numerical experiments show that this approach is very promising in many ways for solving generic multistage stochastic programming, including its superiority in terms of numerical efficiency, as well as the flexibility in testing and analyzing the model.\",\n \"Title: Code design for radar STAP via optimization theory\\nYear: 2010\\n\\nAbstract: In this paper, we deal with the problem of constrained code optimization for radar space-time adaptive processing (STAP) in the presence of colored Gaussian disturbance. At the design stage, we devise a code design algorithm complying with the following optimality criterion: maximization of the detection performance under a control on the regions of achievable values for the temporal and spatial Doppler estimation accuracy, and on the degree of similarity with a pre-fixed radar code. The resulting quadratic optimization problem is solved resorting to a convex relaxation that belongs to the semidefinite program (SDP) class. An optimal solution of the initial problem is then constructed through a suitable rank-one decomposition of an optimal solution of the relaxed one. At the analysis stage, we assess the performance of the new algorithm both on simulated data and on the standard challenging the Knowledge-Aided Sensor Signal Processing and Expert Reasoning (KASSPER) datacube.\",\n \"Title: New variants of finite criss-cross pivot algorithms for linear programming\\nYear: 1999\\n\\nAbstract: In this paper we generalize the so-called first-in-last-out pivot rule and the most-often-selected-variable pivot rule for the simplex method, as proposed in S. Zhang (Operations Research Letters 10 (1991) 189–192) to the criss-cross pivot setting where neither the primal nor the dual feasibility is preserved. The finiteness of the new criss-cross pivot variants is proven.\",\n \"Title: On a Profit Maximizing Location Model\\nYear: 2001\\n\\nAbstract: In this paper we discuss a locational model with a profit-maximizing objective. The model can be illustrated by the following situation. There is a set of potential customers in a given region. A firm enters the market and wants to sell a certain product to this set of customers. The location and demand of each potential customer are assumed to be known. In order to maximize its total profit, the firm has to decide: (1) where to locate its distribution warehouse to serve the customers; (2) the price for its product. Due to existence of competition, each customer holds a reservation price for the product. This reservation price is a decreasing function in the distance to the warehouse. If the actual price is higher than the reservation price, then the customer will turn to some other supplier and hence is lost from the firm's market. The problem of the firm is to find the best location for its warehouse and the best price for its product at the same time in order to maximize the total profit. We show that under certain assumptions on the complexity counts, a special case of this problem can be solved in polynomial time.\",\n \"Title: Dynamic Spectrum Management: Complexity and Duality\\nYear: 2008\\n\\nAbstract: Consider a communication system whereby multiple users share a common frequency band and must choose their transmit power spectral densities dynamically in response to physical channel conditions. Due to co-channel interference, the achievable data rate of each user depends on not only the power spectral density of its own, but also those of others in the system. Given any channel condition and as...\",\n \"Title: Semidefinite Relaxation of Quadratic Optimization Problems\\nYear: 2010\\n\\nAbstract: In this article, we have provided general, comprehensive coverage of the SDR technique, from its practical deployments and scope of applicability to key theoretical results. We have also showcased several representative applications, namely MIMO detection, B¿ shimming in MRI, and sensor network localization. Another important application, namely downlink transmit beamforming, is described in [1]. Due to space limitations, we are unable to cover many other beautiful applications of the SDR technique, although we have done our best to illustrate the key intuitive ideas that resulted in those applications. We hope that this introductory article will serve as a good starting point for readers who would like to apply the SDR technique to their applications, and to locate specific references either in applications or theory.\",\n \"Title: Approximation algorithm for facility location with service installation costs\\nYear: 2008\\n\\nAbstract: In this paper, we study the uncapacitated facility location problem with service installation costs depending on the type of service required. We propose a polynomial-time approximation algorithm with approximation ratio 1.808 which improves the previous approximation ratio of 2.391 of Shmoys, Swamy, and Levi.\",\n \"Title: On a generalized Cournot oligopolistic competition game\\nYear: 2013\\n\\nAbstract: We consider a model whereby players compete for a set of shared resources to produce and sell substitute products in the same market, which can be viewed as a generalization of the classical Cournot oligopolistic competition model, or, from a different angle, the Wardrop type routing model. In particular, we suppose that there are K players, who compete for the usage of resources as well as the sales of the end-products. Moreover, the unit costs of the shared resources and the selling prices of the products are assumed to be affine linear functions in the consumption/production quantities. We show that the price of anarchy in this case is lower bounded by 1/K, and this bound is essentially tight, which manifests the harsh nature of the competitive market for the producers.\",\n \"Title: Polymatroid Optimization, Submodularity, and Joint Replenishment Games\\nYear: 2012\\n\\nAbstract: In this paper we consider the problem of maximizing a separable concave function over a polymatroid. More specifically, we study the submodularity of its optimal objective value in the parameters of the objective function. This question is interesting in its own right and is encountered in many applications. But our research has been motivated mainly by a cooperative game associated with the well-known joint replenishment model. By applying our general results on polymatroid optimization, we prove that this cooperative game is submodular (i.e., its characteristic cost function is submodular) if the joint setup cost is a normalized and nondecreasing submodular function. Furthermore, the same result holds true for a more general one-warehouse multiple retailer game, which affirmatively answers an open question posed by Anily and Haviv [Anily, S., M. Haviv. 2007. The cost allocation problem for the first order interaction joint replenishment model. Oper. Res.55(2) 292--302].\",\n \"Title: A Network Airline Revenue Management Framework Based on Decomposition by Origins and Destinations\\nYear: 2014\\n\\nAbstract: We propose a framework for solving airline revenue management problems on large networks, where the main concern is to allocate the flight leg capacities to customer requests under fixed class fares. This framework is based on a mathematical programming model that decomposes the network into origin-destination pairs so that each pair can be treated as a single flight-leg problem. We first discuss that the proposed framework is quite generic in the sense that not only several well-known models from the literature fit into this framework, but also many single flight-leg models can be easily extended to a network setting through the prescribed construction. Then, we analyze the structure of the overall mathematical programming model and establish its relationship with other models frequently used in practice. The application of the proposed framework is illustrated through two examples based on static and dynamic single-leg models, respectively. These illustrative examples are then benchmarked against several existing methods on a set of real-life network problems.\",\n \"Title: Tensor principal component analysis via convex optimization.\\nYear: 2015\\n\\nAbstract: This paper is concerned with the computation of the principal components for a general tensor, known as the tensor principal component analysis (PCA) problem. We show that the general tensor PCA problem is reducible to its special case where the tensor in question is super-symmetric with an even degree. In that case, the tensor can be embedded into a symmetric matrix. We prove that if the tensor is rank-one, then the embedded matrix must be rank-one too, and vice versa. The tensor PCA problem can thus be solved by means of matrix optimization under a rank-one constraint, for which we propose two solution methods: (1) imposing a nuclear norm penalty in the objective to enforce a low-rank solution; (2) relaxing the rank-one constraint by semidefinite programming. Interestingly, our experiments show that both methods can yield a rank-one solution for almost all the randomly generated instances, in which case solving the original tensor PCA problem to optimality. To further cope with the size of the resulting convex optimization models, we propose to use the alternating direction method of multipliers, which reduces significantly the computational efforts. Various extensions of the model are considered as well.\",\n \"Title: Approximation methods for complex polynomial optimization\\nYear: 2014\\n\\nAbstract: Complex polynomial optimization problems arise from real-life applications including radar code design, MIMO beamforming, and quantum mechanics. In this paper, we study complex polynomial optimization models where the objective function takes one of the following three forms: (1) multilinear; (2) homogeneous polynomial; (3) symmetric conjugate form. On the constraint side, the decision variables belong to one of the following three sets: (1) the $$m$$ m -th roots of complex unity; (2) the complex unity; (3) the Euclidean sphere. We first discuss the multilinear objective function. Polynomial-time approximation algorithms are proposed for such problems with assured worst-case performance ratios, which depend only on the dimensions of the model. Then we introduce complex homogenous polynomial functions and establish key linkages between complex multilinear forms and the complex polynomial functions. Approximation algorithms for the above-mentioned complex polynomial optimization models with worst-case performance ratios are presented. Numerical results are reported to illustrate the effectiveness of the proposed approximation algorithms.\",\n \"Title: On Convergence of the Maximum Block Improvement Method.\\nYear: 2015\\n\\nAbstract: The MBI (maximum block improvement) method is a greedy approach to solving optimization problems where the decision variables can be grouped into a finite number of blocks. Assuming that optimizing over one block of variables while fixing all others is relatively easy, the MBI method updates the block of variables corresponding to the maximally improving block at each iteration, which is arguably a most natural and simple process to tackle block-structured problems with great potentials for engineering applications. In this paper we establish global and local linear convergence results for this method. The global convergence is established under the Lojasiewicz inequality assumption, while the local analysis invokes second-order assumptions. We study in particular the tensor optimization model with spherical constraints. Conditions for linear convergence of the famous power method for computing the maximum eigenvalue of a matrix follow in this framework as a special case. The condition is interpreted in various other forms for the rank-one tensor optimization model under spherical constraints. Numerical experiments are shown to support the convergence property of the MBI method.\",\n \"Title: Inhomogeneous polynomial optimization over a convex set: An approximation approach.\\nYear: 2015\\n\\nAbstract: In this paper, we consider computational methods for optimizing a multivariate inhomogeneous polynomial function over a general convex set. The focus is on the design and analysis of polynomial-time approximation algorithms. The methods are able to deal with optimization models with polynomial objective functions in any fixed degrees. In particular, we first study the problem of maximizing an inhomogeneous polynomial over the Euclidean ball. A polynomial-time approximation algorithm is proposed for this problem with an assured (relative) worst-case performance ratio, which is dependent only on the dimensions of the model. The method and approximation ratio are then generalized to optimize an inhomogeneous polynomial over the intersection of a finite number of co-centered ellipsoids. Furthermore, the constraint set is extended to a general convex compact set. Specifically, we propose a polynomial-time approximation algorithm with a (relative) worst-case performance ratio for polynomial optimization over some convex compact sets, e.g., a polytope. Finally, numerical results are reported, revealing good practical performance of the proposed algorithms for solving some randomly generated instances.\",\n \"Title: Big data - a 21st century science Maginot Line? No-boundary thinking: shifting from the big data paradigm.\\nYear: 2015\\n\\nAbstract: Whether your interests lie in scientific arenas, the corporate world, or in government, you have certainly heard the praises of big data: Big data will give you new insights, allow you to become more efficient, and/or will solve your problems. While big data has had some outstanding successes, many are now beginning to see that it is not the Silver Bullet that it has been touted to be. Here our main concern is the overall impact of big data; the current manifestation of big data is constructing a Maginot Line in science in the 21st century. Big data is not \\\"lots of data\\\" as a phenomena anymore; The big data paradigm is putting the spirit of the Maginot Line into lots of data. Big data overall is disconnecting researchers and science challenges. We propose No-Boundary Thinking (NBT), applying no-boundary thinking in problem defining to address science challenges.\",\n \"Title: Probability Bounds for Polynomial Functions in Random Variables.\\nYear: 2014\\n\\nAbstract: Random sampling is a simple but powerful method in statistics and in the design of randomized algorithms. In a typical application, random sampling can be applied to estimate an extreme value, say maximum, of a function f over a set S subset of R-n. To do so, one may select a simpler (even finite) subset S-0 subset of S, randomly take some samples over S-0 for a number of times, and pick the best sample. The hope is to find a good approximate solution with reasonable chance. This paper sets out to present a number of scenarios for f, S and S-0 where certain probability bounds can be established, leading to a quality assurance of the procedure. In our setting, f is a multivariate polynomial function. We prove that if f is a d-th order homogeneous polynomial in n variables and F is its corresponding super-symmetric tensor, and xi(i) (i = 1, 2, ..., n) are i.i.d. Bernoulli random variables taking 1 or -1 with equal probability, then Prob {f(xi(1), xi(2), ..., xi(n)) >= tau n(-d/2)parallel to F parallel to >= theta, where tau, theta > 0 are two universal constants and parallel to . parallel to(1) denotes the summation of the absolute values of all its entries. Several new inequalities concerning probabilities of the above nature are presented in this paper. Moreover, we show that the bounds are tight in most cases. Applications of our results in optimization are discussed as well.\",\n \"Title: Moments Tensors, Hilbert's Identity, and k-wise Uncorrelated Random Variables.\\nYear: 2014\\n\\nAbstract: In this paper, we introduce a notion to be called k-wise uncorrelated random variables, which is similar but not identical to the so-called k-wise independent random variables in the literature. We show how to construct k-wise uncorrelated random variables by a simple procedure. The constructed random variables can be applied, e.g., to express the quartic polynomial (x(T)Qx)(2), where Q is an n x n positive semidefinite matrix, by a sum of fourth powered polynomial terms, known as Hilbert's identity. By virtue of the proposed construction, the number of required terms is no more than 2n(4) + n. This implies that it is possible to find a (2n(4) + n)-point distribution whose fourth moments tensor is exactly the symmetrization of Q circle times Q. Moreover, we prove that the number of required fourth powered polynomial terms to express (x(T)Qx)(2) is at least n(n +1)/2. The result is applied to prove that computing the matrix 2 bar right arrow 4 norm is NP-hard. Extensions of the results to complex random variables are discussed as well.\",\n \"Title: Characterizing Real-Valued Multivariate Complex Polynomials and Their Symmetric Tensor Representations.\\nYear: 2016\\n\\nAbstract: In this paper we study multivariate polynomial functions in complex variables and their corresponding symmetric tensor representations. The focus is to find conditions under which such complex polynomials always take real values. We introduce the notion of symmetric conjugate forms and general conjugate forms, characterize the conditions for such complex polynomials to be real valued, and present their corresponding tensor representations. New notions of eigenvalues/eigenvectors for complex tensors are introduced, extending similar properties from the Hermitian matrices. Moreover, we study a property of the symmetric tensors, namely, the largest eigenvalue (in the absolute value sense) of a real symmetric tensor is equal to its largest singular value; the result is also known as Banach's theorem. We show that a similar result holds for the complex case as well. Finally, we discuss some applications of the new notion of eigenvalues/eigenvectors for the complex tensors.\",\n \"Title: On implementation of a self-dual embedding method for convex programming\\nYear: 2006\\n\\nAbstract: In this paper, we implement Zhang's method [Zhang, S., 2004, Journal of Global Optimization, 29, 479 - 496], which transforms a general convex optimization problem with smooth convex constraints into a convex conic optimization problem and then apply the techniques of self-dual embedding and central path-following for solving the resulting conic optimization model. A crucial advantage of the approach is that no initial solution is required and the method is particularly suitable when the feasibility status of the problem is unknown. In our implementation, we use a merit function approach proposed by Andersen and Ye [ Andersen, E. D. and Ye, Y., 1998, Computational Optimization and Applications, 10, 243 - 269] to determine the step-size along the search direction. We evaluate the efficiency of the proposed algorithm by observing its performance on some test problems, which include logarithmic functions, exponential functions and quadratic functions in the constraints. Furthermore, we consider in particular the geometric programming and L-p-programming problems. Numerical results of our algorithm on these classes of optimization problems are reported. We conclude that the algorithm is stable, efficient and easy-to-use in general. As the method allows the user to freely select the initial solution, it is natural to take advantage of this and apply the so-called warm-start strategy, whenever the data of a new problem is not too much different from a previously solved problem. This strategy turns out to be effective, according to our numerical experience.\",\n \"Title: On the Global Linear Convergence of the ADMM with MultiBlock Variables.\\nYear: 2015\\n\\nAbstract: The alternating direction method of multipliers (ADMM) has been widely used for solving structured convex optimization problems. In particular, the ADMM can solve convex programs that minimize the sum of N convex functions whose variables are linked by some linear constraints. While the convergence of the ADMM for N = 2 was well established in the literature, it remained an open problem for a long time whether the ADMM for N >= 3 is still convergent. Recently, it was shown in [Chen et al., Math. Program. (2014), DOI 10.1007/s10107-014-0826-5.] that without additional conditions the ADMM for N >= 3 generally fails to converge. In this paper, we show that under some easily verifiable and reasonable conditions the global linear convergence of the ADMM when N >= 3 can still be ensured, which is important since the ADMM is a popular method for solving large-scale multiblock optimization models and is known to perform very well in practice even when N >= 3. Our study aims to offer an explanation for this phenomenon.\",\n \"Title: Local Linear Convergence of ISTA and FISTA on the LASSO Problem.\\nYear: 2016\\n\\nAbstract: We use a model LASSO problem to analyze the convergence behavior of the ISTA and FISTA iterations, showing that both iterations satisfy local linear convergence rate bound when close enough to the solution. Using the observation that FISTA is an accelerated ISTA process, and a spectral analysis of the associated matrix operators, we show that FISTA's convergence rate can slow down as it proceeds, eventually becoming slower than ISTA. This observation leads to a proposed heuristic algorithm to take an ISTA step if it shows more progress compared to FISTA, as measured by the decrease in the objective function. We illustrate the results with some synthetic numerical examples.\",\n \"Title: Improved Algorithms for Machine Allocation in Manufacturing Systems\\nYear: 1994\\n\\nAbstract: In this paper we present two algorithms for a machine allocation problem occurring in manufacturing systems. For the two algorithms presented we prove worst-case performance ratios of 2 and 3/2, respectively. The machine allocation problem we consider is a general convex resource allocation problem, which makes the algorithms applicable to a variety of resource allocation problems. Numerical results are presented for two real-life manufacturing systems.\",\n \"Title: Using duality to solve generalized fractional programming problems\\nYear: 1996\\n\\nAbstract: In this paper we explore the relations between the standard dual problem of a convex generalized fractional programming problem and the “partial” dual problem proposed by Barros et al. (1994). Taking into account the similarities between these dual problems and using basic duality results we propose a new algorithm to directly solve the standard dual of a convex generalized fractional programming problem, and hence the original primal problem, if strong duality holds. This new algorithm works in a similar way as the algorithm proposed in Barros et al. (1994) to solve the “partial” dual problem. Although the convergence rates of both algorithms are similar, the new algorithm requires slightly more restrictive assumptions to ensure a superlinear convergence rate. An important characteristic of the new algorithm is that it extends to the nonlinear case the Dinkelbach-type algorithm of Crouzeix et al. (1985) applied to the standard dual problem of a generalized linear fractional program. Moreover, the general duality results derived for the nonlinear case, yield an alternative way to derive the standard dual of a generalized linear fractional program. The numerical results, in case of quadratic-linear ratios and linear constraints, show that solving the standard dual via the new algorithm is in most cases more efficient than applying directly the Dinkelbach-type algorithm to the original generalized fractional programming problem. However, the numerical results also indicate that solving the alternative dual (Barros et al., 1994) is in general more efficient than solving the standard dual.\",\n \"Title: Convergence of Common Proximal Methods for L1-Regularized Least Squares.\\nYear: 2015\\n\\nAbstract: We compare the convergence behavior of ADMM (alternating direction method of multipliers), [F]ISTA ([fast] iterative shrinkage and thresholding algorithm) and CD (coordinate descent) methods on the model l1-regularized least squares problem (aka LASSO). We use an eigenanalysis of the operators to compare their local convergence rates when close to the solution. We find that, when applicable, CD is often much faster than the other iterations, when close enough to the solution. When far from the solution, the spectral analysis implies that one can often get a sequence of iterates that appears to stagnate, but is actually taking small constant steps toward the solution. We also illustrate how the unaccelerated ISTA algorithm can sometimes be faster compared to FISTA when close enough to the solution.\",\n \"Title: Radar code design with a Peak to average power Ratio constraint: A randomized approximate approach\\nYear: 2011\\n\\nAbstract: This paper considers the problem of radar waveform design in the presence of colored Gaussian disturbance under a Peak to Average power Ratio (PAR) and an energy constraint. Firstly, we focus on the selection of the radar signal optimizing the Signal to Noise Power Ratio (SNR) for a given target Doppler frequency (Algorithm 1). Then, we devise its phase quantized version (Algorithm 2), which forces the waveform phase to lie within a finite alphabet. Both the problems are formulated in terms of NP-hard non-convex quadratic optimization programs; in order to solve them, we resort to Semidefinite Programming (SDP) relaxation and randomization techniques, providing provable-quality sub-optimal solutions with a polynomial time computational complexity. Finally, we analyze the performance in terms of detection capability and robustness with respect to Doppler shifts.\",\n \"Title: Structured Nonconvex and Nonsmooth Optimization: Algorithms and Iteration Complexity Analysis.\\nYear: 2019\\n\\nAbstract: Nonconvex and nonsmooth optimization problems are frequently encountered in much of statistics, business, science and engineering, but they are not yet widely recognized as a technology in the sense of scalability. A reason for this relatively low degree of popularity is the lack of a well developed system of theory and algorithms to support the applications, as is the case for its convex counterpart. This paper aims to take one step in the direction of disciplined nonconvex and nonsmooth optimization. In particular, we consider in this paper some constrained nonconvex optimization models in block decision variables, with or without coupled affine constraints. In the absence of coupled constraints, we show a sublinear rate of convergence to an \\\\(\\\\epsilon \\\\)-stationary solution in the form of variational inequality for a generalized conditional gradient method, where the convergence rate is dependent on the Hölderian continuity of the gradient of the smooth part of the objective. For the model with coupled affine constraints, we introduce corresponding \\\\(\\\\epsilon \\\\)-stationarity conditions, and apply two proximal-type variants of the ADMM to solve such a model, assuming the proximal ADMM updates can be implemented for all the block variables except for the last block, for which either a gradient step or a majorization–minimization step is implemented. We show an iteration complexity bound of \\\\(O(1/\\\\epsilon ^2)\\\\) to reach an \\\\(\\\\epsilon \\\\)-stationary solution for both algorithms. Moreover, we show that the same iteration complexity of a proximal BCD method follows immediately. Numerical results are provided to illustrate the efficacy of the proposed algorithms for tensor robust PCA and tensor sparse PCA problems.\",\n \"Title: On New Classes of Nonnegative Symmetric Tensors.\\nYear: 2017\\n\\nAbstract: In this paper we introduce three new classes of nonnegative forms (or equivalently, symmetric tensors) and their extensions. The newly identified nonnegative symmetric tensors constitute distinctive convex cones in the space of general symmetric tensors (order six or above). For the special case of quartic forms, they collapse into the set of convex quartic homogeneous polynomial functions. We discuss the properties and applications of the new classes of nonnegative symmetric tensors in the context of polynomial and tensor optimization. Numerical experiments for solving certain polynomial optimization models based on the new classes of nonnegative symmetric tensors are presented.\",\n \"Title: A smoothing SQP framework for a class of composite $$L_q$$Lq minimization over polyhedron\\nYear: 2016\\n\\nAbstract: The composite $$L_q~(0\",\n \"Title: A Sparse Completely Positive Relaxation of the Modularity Maximization for Community Detection.\\nYear: 2017\\n\\nAbstract: In this paper, we consider the community detection problem under either the stochastic block model (SBM) assumption or the degree-correlated SBM assumption. The modularity maximization formulation for the community detection problem is NP-hard in general. In this paper, we propose a sparse and low-rank completely positive relaxation for the modularity maximization problem, we then develop an efficient row-by-row (RBR)-type block coordinate descent algorithm to solve the relaxation and prove an O(1/root N) convergence rate to a stationary point, where N is the number of iterations. A fast rounding scheme is constructed to retrieve the community structure from a solution to the above relaxation. Nonasymptotic high probability bounds on the misclassification rate are established to justify our approach. We further develop an asynchronous parallel RBR algorithm to speed up the convergence. Extensive numerical experiments on both synthetic and real world networks show that the proposed approach enjoys advantages in both clustering accuracy and numerical efficiency. Our numerical results indicate that the newly proposed method is a competitive alternative for the community detection problem on sparse networks with over 50 million nodes.\",\n \"Title: Highly Accurate Model For Prediction Of Lung Nodule Malignancy With Ct Scans\\nYear: 2018\\n\\nAbstract: Computed tomography (CT) examinations are commonly used to predict lung nodule malignancy in patients, which are shown to improve noninvasive early diagnosis of lung cancer. It remains challenging for computational approaches to achieve performance comparable to experienced radiologists. Here we present NoduleX, a systematic approach to predict lung nodule malignancy from CT data, based on deep learning convolutional neural networks (CNN). For training and validation, we analyze >1000 lung nodules in images from the LIDC/IDRI cohort. All nodules were identified and classified by four experienced thoracic radiologists who participated in the LIDC project. NoduleX achieves high accuracy for nodule malignancy classification, with an AUC of similar to 0.99. This is commensurate with the analysis of the dataset by experienced radiologists. Our approach, NoduleX, provides an effective framework for highly accurate nodule malignancy prediction with the model trained on a large patient population. Our results are replicable with software available at http://bioinformatics.astate.edu/NoduleX.\",\n \"Title: On the Information-Adaptive Variants of the ADMM: An Iteration Complexity Perspective.\\nYear: 2018\\n\\nAbstract: Designing algorithms for an optimization model often amounts to maintaining a balance between the degree of information to request from the model on the one hand, and the computational speed to expect on the other hand. Naturally, the more information is available, the faster one can expect the algorithm to converge. The popular algorithm of ADMM demands that objective function is easy to optimize once the coupled constraints are shifted to the objective with multipliers. However, in many applications this assumption does not hold; instead, often only some noisy estimations of the gradient of the objective—or even only the objective itself—are available. This paper aims to bridge this gap. We present a suite of variants of the ADMM, where the trade-offs between the required information on the objective and the computational complexity are explicitly given. The new variants allow the method to be applicable on a much broader class of problems where only noisy estimations of the gradient or the function values are accessible, yet the flexibility is achieved without sacrificing the computational complexity bounds.\",\n \"Title: Accelerated primal–dual proximal block coordinate updating methods for constrained convex optimization\\nYear: 2018\\n\\nAbstract: Block coordinate update (BCU) methods enjoy low per-update computational complexity because every time only one or a few block variables would need to be updated among possibly a large number of blocks. They are also easily parallelized and thus have been particularly popular for solving problems involving large-scale dataset and/or variables. In this paper, we propose a primal---dual BCU method for solving linearly constrained convex program with multi-block variables. The method is an accelerated version of a primal---dual algorithm proposed by the authors, which applies randomization in selecting block variables to update and establishes an O(1 / t) convergence rate under convexity assumption. We show that the rate can be accelerated to $$O(1/t^2)$$O(1/t2) if the objective is strongly convex. In addition, if one block variable is independent of the others in the objective, we then show that the algorithm can be modified to achieve a linear rate of convergence. The numerical experiments show that the accelerated method performs stably with a single set of parameters while the original method needs to tune the parameters for different datasets in order to achieve a comparable level of performance.\",\n \"Title: Low-M-Rank Tensor Completion and Robust Tensor PCA.\\nYear: 2018\\n\\nAbstract: In this paper, we propose a new approach to solve low-rank tensor completion and robust tensor PCA. Our approach is based on some novel notion of (even-order) tensor ranks, to be called the M-rank, the symmetric M-rank, and the strongly symmetric M-rank. We discuss the connections between these new tensor ranks and the CP-rank and the symmetric CP-rank of an even-order tensor. We show that the M-r...\",\n \"Title: An Optimal High-Order Tensor Method for Convex Optimization\\nYear: 2019\\n\\nAbstract: This paper is concerned with finding an optimal algorithm for minimizing a composite convex objective function. The basic setting is that the objective is the sum of two convex functions: the first function is smooth with up to the dth-order derivative information available, and the second function is possibly nonsmooth, but its proximal tensor mappings can be computed approximately in an efficient manner. The problem is to find-in that setting-the best possible (optimal) iteration complexity for convex optimization. Along that line, for the smooth case (without the second nonsmooth part in the objective), Nesterov proposed an optimal algorithm for the first-order methods (d = 1) with iteration complexity O(1/k(2)), whereas high-order tensor algorithms (using up to general dth-order tensor information) with iteration complexity O(1/k(d+1)) were recently established. In this paper, we propose a new high-order tensor algorithm for the general composite case, with the iteration complexity of O(1/k((3d+1)/2)), which matches the lower bound for the dth-order methods as previously established and hence is optimal. Our approach is based on the accelerated hybrid proximal extragradient (A-HPE) framework proposed by Monteiro and Svaiter, where a bisection procedure is installed for each A-HPE iteration. At each bisection step, a proximal tensor subproblem is approximately solved, and the total number of bisection steps per A-HPE iteration is shown to be bounded by a logarithmic factor in the precision required.\",\n \"Title: On lower iteration complexity bounds for the convex concave saddle point problems\\nYear: 2022\\n\\nAbstract: In this paper, we study the lower iteration complexity bounds for finding the saddle point of a strongly convex and strongly concave saddle point problem: \\n \\n \\n \\n $$\\\\min _x\\\\max _yF(x,y)$$\\n \\n . We restrict the classes of algorithms in our investigation to be either pure first-order methods or methods using proximal mappings. For problems with gradient Lipschitz constants (\\n \\n \\n \\n $$L_x, L_y$$\\n \\n and \\n \\n \\n \\n $$L_{xy}$$\\n \\n ) and strong convexity/concavity constants (\\n \\n \\n \\n $$\\\\mu _x$$\\n \\n and \\n \\n \\n \\n $$\\\\mu _y$$\\n \\n ), the class of pure first-order algorithms with the linear span assumption is shown to have a lower iteration complexity bound of \\n \\n \\n \\n $$\\\\Omega \\\\,\\\\left( \\\\sqrt{\\\\frac{L_x}{\\\\mu _x}+\\\\frac{L_{xy}^2}{\\\\mu _x\\\\mu _y}+\\\\frac{L_y}{\\\\mu _y}}\\\\cdot \\\\ln \\\\left( \\\\frac{1}{\\\\epsilon }\\\\right) \\\\right) $$\\n \\n , where the term \\n \\n \\n \\n $$\\\\frac{L_{xy}^2}{\\\\mu _x\\\\mu _y}$$\\n \\n explains how the coupling influences the iteration complexity. Under several special parameter regimes, this lower bound has been achieved by corresponding optimal algorithms. However, whether or not the bound under the general parameter regime is optimal remains open. Additionally, for the special case of bilinear coupling problems, given the availability of certain proximal operators, a lower bound of \\n \\n \\n \\n $$\\\\Omega \\\\left( \\\\sqrt{\\\\frac{L_{xy}^2}{\\\\mu _x\\\\mu _y}}\\\\cdot \\\\ln (\\\\frac{1}{\\\\epsilon })\\\\right) $$\\n \\n is established under the linear span assumption, and optimal algorithms have already been developed in the literature. By exploiting the orthogonal invariance technique, we extend both lower bounds to the general pure first-order algorithm class and the proximal algorithm class without the linear span assumption. As an application, we apply proper scaling to the worst-case instances, and we derive the lower bounds for the general convex concave problems with \\n \\n \\n \\n $$\\\\mu _x = \\\\mu _y = 0$$\\n \\n . Several existing results in this case can be deduced from our results as special cases.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":84,"string":"84"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":260,"string":"260"}}},{"rowIdx":261,"cells":{"question_id":{"kind":"string","value":"Bill Lin"},"question":{"kind":"string","value":"Generate an abstract for the title \"Robust Statistics Counter Arrays with Interleaved Memories\" using the following items: 1. Statistics counters\n2. DRAM-based architecture\n3. Traffic bursts\n4. Performance optimization\n5. Overflow probability"},"answer":{"kind":"string","value":"Statistics counters are essential in network measurement on tracking various network statistics and implementing various network counting sketches. For such applications it is crucial to maintain a large number of statistics counters at very high speeds. On the Internet with millions of flows, potentially millions of counters are required to be updated at wirespeed of 40 Gb/s and beyond. It is widely accepted that SRAM is too costly to store such large counter arrays entirely, and DRAM is too slow to catch up with the line rate. In this paper, we propose a DRAM-based architecture that takes advantage of the performance of modern commodity DRAM by interleaving counter updates to multiple memory banks. Our architecture is based on the observation that most flows on the Internet consist of multiple packets that are transmitted during a relatively short period of time, which are referred to as traffic bursts. Our proposed architecture makes use of a simple randomization scheme and a set of small fully associative request queues to statistically guarantee a near-perfect load balancing of counter updates to the memory banks. The architecture explores the benefit of traffic bursts to greatly reduce the maximum size of the request queues while providing a diminishing overflow probability guarantee. We also develop queuing models to show that as long as the flow sizes are heavy-tailed distributed due to traffic bursts, the maximum request queue length is always bounded by a small constant. The simulation results confirm the effectiveness of our queuing models. The proposed statistics counter arrays can effectively maintain line rate updates to a large number of counters while guaranteeing a diminishing overflow probability in the system."},"correct_answer":{"kind":"string","value":"Statistics counters are essential in network measurement on tracking various network statistics and implementing various network counting sketches. For such applications it is crucial to maintain a large number of statistics counters at very high speeds. On the Internet with millions of flows, potentially millions of counters are required to be updated at wirespeed of 40 Gb/s and beyond. It is widely accepted that SRAM is too costly to store such large counter arrays entirely, and DRAM is too slow to catch up with the line rate. In this paper, we propose a DRAM-based architecture that takes advantage of the performance of modern commodity DRAM by interleaving counter updates to multiple memory banks. Our architecture is based on the observation that most flows on the Internet consist of multiple packets that are transmitted during a relatively short period of time, which are referred to as traffic bursts. Our proposed architecture makes use of a simple randomization scheme and a set of small fully associative request queues to statistically guarantee a near-perfect load balancing of counter updates to the memory banks. The architecture explores the benefit of traffic bursts to greatly reduce the maximum size of the request queues while providing a diminishing overflow probability guarantee. We also develop queuing models to show that as long as the flow sizes are heavy-tailed distributed due to traffic bursts, the maximum request queue length is always bounded by a small constant. The simulation results confirm the effectiveness of our queuing models. The proposed statistics counter arrays can effectively maintain line rate updates to a large number of counters while guaranteeing a diminishing overflow probability in the system."},"documents":{"kind":"list like","value":["Title: BRICK: A Novel Exact Active Statistics Counter Architecture\nYear: 2008\n\nAbstract: In this paper, we present an exact active statistics counter architecture called Bucketized Rank Indexed Counters (BRICK) that can efficiently store per-flow variable-width statistics counters entirely in SRAM while supporting both fast updates and lookups (e.g., 40-Gb/s line rates). BRICK exploits statistical multiplexing by randomly bundling counters into small fixed-size buckets and supports dynamic sizing of counters by employing an innovative indexing scheme called rank indexing. Experiments with Internet traces show that our solution can indeed maintain large arrays of exact active statistics counters with moderate amounts of SRAM.","Title: Pipelined Van Emde!Boas Tree: Algorithms, Analysis, And Applications\nYear: 2007\n\nAbstract: Priority queues are essential for various network processing applications, including per-flow queueing with Quality-of-Service (QoS) guarantees, management of large fast packet buffers, and management of statistics counters. In this paper, we propose a new data structure for implementing high-performance priority queues based on a pipelined version of the van Emde Boas tree. We show that we can achieve O(1) amortized time operations using our architecture, but we can achieve this algorithmic efficiency using only O(log log u) number of pipelined stages, where u is the size of the universe used to represent the priority keys.","Title: Block-based packet buffer with deterministic packet departures\nYear: 2010\n\nAbstract: Routers need to store temporarily a large number of packets in response to congestion. DRAM is typically needed to implement large packet buffers, but DRAM devices have worst-case random access latencies that are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into three categories: prefetching-based, randomization-based, and reservation-based. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. In this paper, we present an efficient reservation-based packet buffer architecture based on the concept of blocks. The proposed block-based solution achieves an order of magnitude reduction in the total SRAM size. It is scalable to growing packet storage requirements in routers while matching increasing line rates.","Title: Communication based logic partitioning\nYear: 1992\n\nAbstract: ln this paper we address the problem of partitioning, or decomposing a combinational logic specification. Most partitioning algorithms partition circuits by manipulating the implementation of the circuit, i.e., the gates, latches, etc. that realize the circuit. Our method operates on the logic speci~caiion bejore the synthesis and mapping steps have been performed. Thts g~ves us more freedom to find a good circuit decomposition and allows us to manipulate the logic as needed. The main goal oj OUT algorithm is to minimize the number oj pans needed to implement the vesulting partitions. This is accomplished by adding logic to reduce the numbeT oj pins, and by minimizing the number of pins required jor inter-pai-tttion communication by encoding the signals that flow between partitions. We have implemented our algomthrns z.sing Binary Decision Diagrams and have observed reductions oj up to 79 % in the number of pins added for the partition.","Title: Efficient symbolic support manipulation\nYear: 1993\n\nAbstract: An incompletely specified function can be given by an interval (g, h) or alternatively by a function f and a don't care set d. Depending on the assignment of don't cares, a different compatible function with a possibly support set may be derived. In this paper, efficient symbolic algorithms based on BDDs are presented for finding a compatible function with the minimum support. Efficient solution to this problem has important application in FPGA synthesis","Title: Explicit modeling of control and data for improved NoC router estimation\nYear: 2012\n\nAbstract: Networks-on-Chip (NoCs) are scalable fabrics for interconnection networks used in many-core architectures. ORION2.0 is a widely adopted NoC power and area estimation tool; however, its models for area, power and gate count can have large errors (up to 110% on average) versus actual implementation. In this work, we propose a new methodology that analyzes netlists of NoC routers that have been placed and routed by commercial tools, and then performs explicit modeling of control and data paths followed by regression analysis to create highly accurate gate count, area and power models for NoCs. When compared with actual implementations, our new models have average estimation errors of no more than 9.8% across microarchitecture and implementation parameters. We further describe modeling extensions that enable more detailed flit-level power estimation when integrated with simulation tools such as GARNET.","Title: A System Design Methodology for Telecommunication Network Applications\nYear: 1997\n\nAbstract: We describe a system design methodology, well-suited for telecom network applications. This methodology is being developed into a compiler called Matisse. The entry point for this methodology is a system specification model that is first compiled into an abstract machine. The abstract machine is implementation-independent, which permits the exploration of different embedded hardware/software realizations. The proposed methodology and tools bridge the gap between system specification and synthesis tools commercially available. This yields several advantages over the design methodology currently used in industry.","Title: Software synthesis of process-based concurrent programs\nYear: 1998\n\nAbstract: We present a Petri net theoretic approach to the software synthesis problem that can synthesize ordinary C programs from process-based concurrent specifications without the need for a run-time multithreading environment. The synthesized C programs can be readily retargeted to different processors using available optimizing C compilers. Our compiler can also generate sequential Java programs as output, which can also be readily mapped to a target processor without the need for a multithreading environment. Initial results demonstrate significant potentials for improvements over current run-time solutions.","Title: A communicating Petri net model for the design of concurrent asynchronous modules\nYear: 1994\n\nAbstract: Current asynchronous tools are focussed mainly on the design of a single interface module. In many applications, one must design interacting interface modules that potentially communicate in complex and intricate ways. When designing communicating asynchronous modules, several difficult problems arise. First, even if each individual module can be synthesized correctly, according to the environmental assumptions specified for that module, the com- position of the communicating modules may not work properly. Thus, one needs to have a way to model how the modules interact with each other, and to verify that their cooperation is consistent. In addition, means should be provided for communication and syn- chronization at a level higher than signal transitions, and for ex- ploiting the communicating nature of these modules in optimiza- tion. This paper proposes a communicating Petri net model for de- scribing communicating asynchronous modules. Each module is modeled by means of a labeled Petri net that extends the widely used Signal Transition Graph model by providing an abstract syn- chronization mechanism based on rendez-vous semantics. This en- ables the designer to specify high-level communication as well as low-level details such as signal transitions. Abstract synchroniza- tion events are expanded automatically to low-level handshake sig- nals. We have developed a new algebra for communicating Petri nets that is applicable to general Petri nets, involves no unfolding, and defines hiding as generalized net contraction. We have devel- oped methods based on this formal algebra that can be used to ma- nipulate communicating interface modules, to verify their consis- tency, and to use them as a basis for optimizations. in a concise way is needed as system interfaces are naturally expressed as separate modules, and in which the individual systems themselves are also described separately. Also, the implementation may force a separate physical implementation. Real-life designs show that asynchronous system designs are inherently distributive and involve highly interactive controllers. While work based on Hoare's CSP model have addressed some problems with communi- cating modules (2, 6), these methods are mainly based on syntax- directed translation techniques, which have not shown the same degree of automation and optimization as their STG based counter- parts. When designing communicating asynchronous interface mod- ules, a number of difficult problems arise. A major issue is correct- ness. Although current methods guarantee that each separate block is synthesized correctly, they do not guarantee the global correct- ness of the composed system. To reconcile such problems, one needs to have ways to model how the interface modules interact with each other and to verify that their cooperation is consistent. For this, we propose a high-level communicating Petri net model, called Communicating Interface Processes (CIP) for describing communicating system interfaces. Each individual interface com- ponent is modeled by means of a labeled Petri net that extends the widely used STG model by providing an abstract synchronization mechanism based on rendez-vous semantics. This enables the designer to model how the concurrent interface processes cooperate and to specify high-level communication as well as low-level details such as signal transitions. Abstract synchronization events are expanded automatically to low-level handshake signals at a later stage, which can help to avoid potential communication mis- matches that often occur with signal-level interactions. Since these ev ents are expanded to a synchronization mechanism, correctness is ensured. Accordingly, we hav e developed a new algebra on this model of abstract communication graphs to describe and formally reason about manipulations from synthesis and analysis points of view.","Title: Design and Analysis of a Robust Pipelined Memory System\nYear: 2010\n\nAbstract: Many network processing applications require wire-speed access to large data structures or a large amount of flow-level data, but the capacity of SRAMs is woefully inadequate in many cases. In this paper, we analyze a robust pipelined memory architecture that can emulate an ideal SRAM by guaranteeing with very high probability that the output sequence produced by the pipelined memory architecture is the same as the one produced by an ideal SRAM under the same sequence of memory read and write operations, except time-shifted by a fixed pipeline delay of ¿. The design is based on the interleaving of DRAM banks together with the use of a reservation table that serves in part as a data cache. In contrast to prior interleaved memory solutions, our design is robust even under adversarial memory access patterns, which we demonstrate through a rigorous worst-case theoretical analysis using a combination of convex ordering and large deviation theory.","Title: Randomized Throughput-Optimal Oblivious Routing for Torus Networks\nYear: 2013\n\nAbstract: In this paper, we study the problem of optimal oblivious routing for 1D and 2D torus networks. We introduce a new closed-form oblivious routing algorithm called W2TURN that is worst-case throughput optimal for 2D torus networks. W2TURN is based on a weighted random selection of paths that contain at most two turns. Restricting the maximum number of turns in routing paths to just two enables a simple deadlock-free implementation of W2TURN. In terms of average hop count, W2TURN outperforms the best previously known closed-form worst-case throughput optimal routing algorithm called IVAL [CHECK END OF SENTENCE]. When the network radix is odd, W2TURN achieves the minimum average hop count that can be achieved with 2-turn paths while remaining worst-case throughput optimal. When the network radix is even, W2TURN comes very close to achieving the minimum average hop count while remaining worst-case throughput optimal, within just 0.72 percent on a 12\\times 12 torus. We also describe another routing algorithm based on weighted random selection of paths with at most two turns called I2TURN and show that I2TURN is equivalent to IVAL. However, I2TURN eliminates the need for loop removal at runtime and provides a closed-form analytical expression for evaluating the average hop count. The latter enables us to demonstrate analytically that W2TURN strictly outperforms IVAL (and I2TURN) in average hop count. Finally, we present a new optimal weighted random routing algorithm for rings called Weighted Random Direction (WRD). WRD provides a closed-form expression for the optimal distribution of traffic along the minimal and nonminimal directions in a ring topology to achieve minimum average hop count while guaranteeing optimal worst-case throughput. Based on our evaluations, in addition to being worst-case throughput optimal, W2TURN and WRD also perform well in the average case, and outperform the best previously known worst-case throughput optimal routing algorithms with closed-form descriptions in latency and throughput over a wide range of traffic patterns.","Title: Adaptive Frequency Counting over Bursty Data Streams\nYear: 2007\n\nAbstract: We investigate the problem of frequent itemset mining over a data stream with bursty traffic. In many modern applications, data arrives at a system as a continuous stream of transactions. In many cases, the arrvial rate of transactions fluctuates wildly. Traditional stream mining algorithms, such as Lossy Counting (LC), were generally designed to handle data streams with steady data arrival rates. We show that LC suffers significant loss of accuracy when the data stream is bursty. We propose the Adaptive Frequency Counting algorithm (AFC) to handle bursty data. AFC has a feedback mechanism that dynamically adjusts the mining speed to cope with the changing data arrival rate. Through extensive experiments, we show that AFC outperforms LC under bursty traffics in terms of the accuracy of the set of freqeunt itemsets.","Title: Application-specific Network-on-Chip architecture synthesis based on set partitions and Steiner Trees\nYear: 2008\n\nAbstract: This paper considers the problem of synthesizing application-specific Network-on-Chip (NoC) architectures. We propose two heuristic algorithms called CLUSTER and DECOMPOSE that can systematically examine different set partitions of communication flows, and we propose Rectilinear-Steiner-Tree (RST) based algorithms for generating an efficient network topology for each group in the partition. Different evaluation functions in fitting with the implementation backend and the corresponding implementation technology can be incorporated into our solution framework to evaluate the implementation cost of the set partitions and RST topologies generated. In particular, we experimented with an implementation cost model based on the power consumption parameters of a 70nm process technology where leakage power is a major source of energy consumption. Experimental results on a variety of NoC benchmarks showed that our synthesis results can on average achieve a 6.92x reduction in power consumption over the best standard mesh implementation. To further gauge the effectiveness of our heuristic algorithms, we also implemented an exact algorithm that enumerates all distinct set partitions. For the benchmarks where exact results could be obtained, our CLUSTER and DECOMPOSE algorithms on average can achieve results within 1% and 2% of exact results, with execution times all under 1 second whereas the exact algorithms took as much as 4.5 hours.","Title: A general state graph transformation framework for asynchronous synthesis\nYear: 1994\n\nAbstract: No abstract available.","Title: The taming of the shrew: mitigating low-rate TCP-targeted attack\nYear: 2010\n\nAbstract: A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission timeout mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from the victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulation results indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router mechanisms.","Title: Trace-driven optimization of networks-on-chip configurations\nYear: 2010\n\nAbstract: Networks-on-chip (NoCs) are becoming increasingly important in general-purpose and application-specific multi-core designs. Although uniform router configurations are appropriate for general-purpose NoCs, router configurations for application-specific NoCs can be non-uniformly optimized to application-specific traffic characteristics. In this paper, we specifically consider the problem of virtual channel (VC) allocation in application-specific NoCs. Prior solutions to this problem have been average-rate driven. However, average-rate models are poor representations of real application traffic, and can lead to designs that are poorly matched to the application. We propose an alternate trace-driven paradigm in which configuration of NoCs is driven by application traces. We propose two simple greedy trace-driven VC allocation schemes. Compared to uniform allocation, we observe up to 51% reduction in the number of VCs under a given average packet latency constraint, or up to 74% reduction in average packet latency with same number of VCs. Our results suggest that average-rate driven methods cannot effectively select appropriate links for VC allocation because they fail to consider the impact of traffic bursts. As a case study, we compare our proposed approach with an existing average-rate driven method [9] and observe up to 35% reduction in the number of VCs for a given target latency.","Title: Design and performance analysis of a DRAM-based statistics counter array architecture\nYear: 2009\n\nAbstract: The problem of maintaining efficiently a large number (say millions) of statistics counters that need to be updated at very high speeds (e.g. 40 Gb/s) has received considerable research attention in recent years. This problem arises in a variety of router management and data streaming applications where large arrays of counters are used to track various network statistics and implement various counting sketches. It proves too costly to store such large counter arrays entirely in SRAM while DRAM is viewed as too slow for providing wirespeed updates at such high speeds. In this paper, we propose a DRAM-based counter architecture that can effectively maintain wirespeed updates to large counter arrays. The proposed approach is based on the observation that modern commodity DRAM architectures, driven by aggressive performance roadmaps for consumer applications (e.g. video games), have advanced architecture features that can be exploited to make a DRAM-based solution practical. In particular, we propose a randomized DRAM architecture that can harness the performance of modern commodity DRAM offerings by interleaving counter updates to multiple memory banks. The proposed architecture makes use of a simple randomization scheme, a small cache, and small request queues to statistically guarantee a near-perfect load-balancing of counter updates to the DRAM banks. The statistical guarantee of the proposed scheme is proven using a novel combination of convex ordering and large deviation theory. Our proposed counter scheme can support arbitrary increments and decrements at wirespeed, and it can support different number representations, including both integer and floating point number representations.","Title: BRICK: a novel exact active statistics counter architecture\nYear: 2011\n\nAbstract: In this paper, we present an exact active statistics counter architecture called Bucketized Rank Indexed Counters (BRICK) that can efficiently store per-flow variable-width statistics counters entirely in SRAM while supporting both fast updates and lookups (e.g., 40-Gb/s line rates). BRICK exploits statistical multiplexing by randomly bundling counters into small fixed-size buckets and supports dynamic sizing of counters by employing an innovative indexing scheme called rank indexing. Experiments with Internet traces show that our solution can indeed maintain large arrays of exact active statistics counters with moderate amounts of SRAM.","Title: Per-flow Queue Scheduling with Pipelined Counting Priority Index\nYear: 2011\n\nAbstract: For advanced per-flow service disciplines at high-speed network links, it is essential to maintain priority queues in sorted order. The scalable priority queue implementation requires managing a large number of queues at ever increasing line speeds. In this paper, we propose novel solutions to the management of priority queues using a previously proposed pipelined Counting Priority Index (pCPI) structure. We consider applications in which hundreds of thousands of priority queues may need to be maintained at line rate at each line card. We provide solutions to two specific problems: the mapping of packet departure times into a priority index, and the locating of the priority queue that contains the packet for a given departure time. We show that the pCPI structure can be effectively implemented for scheduling packets that are maintained in a large number of priority queues.","Title: Efficient state assignment framework for asynchronous state graphs\nYear: 1995\n\nAbstract: This paper presents a new efficient state assignment framework for synthesizing asynchronous state graphs. This framework operates purely at the state graph level and is applicable to a broad class of behaviors. In this paper we focus the framework for solving the complete state coding problem. This method has been automated and applied to a large set of asynchronous circuits. It achieves significant improvements in terms of both circuit area and computation time.","Title: A time abstraction method for efficient verification of communicating systems\nYear: 1994\n\nAbstract: An important practical approach to automatic verifi- cation of finite state concurrent systems is temporal logic model checking. However, a major barrier towards wider application of such methods is the state explosion problem that often occurs during the composition of complex communicating systems. In addition to being large, many systems have very deep state spaces as well. In this paper, we propose an abstraction method based on time abstraction which can significantly reduce both the size as well as the depth of the state space that must be explored during model check- ing. It is especially suited for applications involving systems that are loosely coupled in the sense that communication activity is rela- tively sparse, such as applications involving DSPs, which have large intervals of autonomous processing, with communication activity in between. All properties expressible with the temporal logic CTL or CTL - are strongly preserved under the proposed abstraction. In particular, we give a method that can replace a chain of states by a single state with a time label. The abstracted model is represented by means of a timed label transition system model. We give a composi- tion algorithm for composing the individually time abstracted models to form a global model that can be converted back to a conventional, but potentially much reduced, state space suitable for model checking. Furthermore, a similar approach can be followed in dealing with wait states in which a system is idling while waiting for an escape signal. For many cases, our approach is successful in alleviating the state explosion problem that often arises in composition of communicating systems.","Title: A generalized state assignment theory for transformations on signal transition graphs\nYear: 1994\n\nAbstract: In this article, we propose a global assignment theory for encoding state graph transformations. A con- straint satisfaction framework is proposed that can guarantee necessary and sufficient conditions for a state graph assignment to result in a transformed state graph that is free of critical races. Performing transformations at the state graph level has the advantage that the requirements imposed on the initial STG are very weak. Unlike previous methods, the initial STG need not be a live, safe, nor a free choice net. The only requirement is that the correspond- ing initial state graph is finite, connected, and has a consistent state assignment. Hence, a very broad range of signal transition graphs can be synthesized. The transformations achievable using the proposed framework correspond to very complex transformations on signal transition graphs. Even transformations that convert a free choice net into a correct non-free choice net and a 1-safe net into a correct 2-safe net are feasible. Addition of transitions that do not follow the Petri net firing rule is also possible. Even though our method can search a large solution space, we will show that it is possible to solve the problem in an exact way in acceptable CPU times in many practical cases.","Title: A randomized interleaved DRAM architecture for the maintenance of exact statistics counters\nYear: 2009\n\nAbstract: We extend a previously proposed randomized interleaved DRAM architecture [1] that can maintain wirespeed updates (say 40 Gb/s) to a large array (say millions) of counters. It works by interleaving updates to randomly distributed counters across multiple memory banks. Though unlikely, an adversary can conceivably overload a memory bank by triggering frequent updates to the same counter. In this work, we show this \"attack\" can be mitigated through caching pending updates, which can catch repeated updates to the same counter within a sliding time window. While this architecture of combining randomization with caching is simple and straightforward, the primary contribution of this work is to rigorously prove that it can handle with overwhelming probability all adversarial update patterns, using a combination of tail bound techniques, convex ordering theory, and queueing analysis.","Title: Succinct priority indexing structures for the management of large priority queues\nYear: 2009\n\nAbstract: Priority queues are an essential building block for implementing advanced per-flow service disciplines at high-speed network links. In this paper, we propose novel solutions to the scalable implementation of priority queues by decomposing the problem into two parts, a succinct priority index in SRAM that can efficiently maintain a real-time sorting of priorities, coupled with a DRAM-based implementation of large packet buffers. In particular, we propose three related novel succinct priority index data structures for implementing high-speed priority indexes: a Priority-Index (PI), a Counting-Priority-Index (CPI), and a Pipelined Counting-Priority-Index (Pipelined CPI). We show that all three structures can be very compactly implemented in SRAM using only Theta(U) space, where U is the size of the universe required to implement the priority keys (timestamps). We also show that our proposed priority index structures can be implemented very efficiently as well by leveraging hardware-optimized instructions that are readily available in modern 64-bit microprocessors. The operations on the PI and CPI structures take Theta(logW U) time, where W is the processor word-length (i.e., W = 64 bits). Alternatively, operations on the Pipelined CPI structure take constant time with only Theta(logW U) pipeline stages. Finally, we show the application of our proposed priority index structures for scalable management of large packet buffers at line speeds.","Title: Destination-based adaptive routing on 2D mesh networks\nYear: 2010\n\nAbstract: The choice of routing algorithm plays a vital role in the performance of on-chip interconnection networks. Adaptive routing is appealing because it offers better latency and throughput than oblivious routing, especially under non-uniform and bursty traffic. The performance of an adaptive routing algorithm is determined by its ability to accurately estimate congestion in the network. In this regard, maintaining global congestion information using a separate monitoring network offers better congestion visibility into distant parts of the network than solutions relying only on local congestion state. However, the main challenge in designing such routing schemes is to keep the logic and bandwidth overhead as low as possible to fit into the tight power, area and delay budgets of on-chip routers. In this paper, we propose a minimal destination-based adaptive routing strategy (DAR) where every node estimates the delay to every other node in the network, and routing decisions are based on these per-destination delay estimates. DAR outperforms Regional Congestion Awareness (RCA) [7], the best previously known adaptive routing algorithm that uses non-local congestion knowledge. This is because the per-destination delay estimates in DAR are more accurate and not corrupted by congestion on links outside the admissible routing paths to the destination. We show that DAR outperforms minimal adaptive routing by up to 65% and RCA by up to 41% in terms of latency on SPLASH-2 benchmarks. It also outperforms these algorithms in latency and throughput under synthetic traffic patterns on both 8x8 and 16x16 mesh topologies.","Title: Performance-driven synthesis of asynchronous controllers\nYear: 1994\n\nAbstract: We examine the implications of a new hazard-free combinational logic synthesis method, which generates multiplexor trees from binary decision diagrams (BDDs)—representations of logic functions factored recursively with respect to input variables—on extended burst-mode asynchronous synthesis. First, the use of the BDD-based synthesis reduces the constraints on state minimization and assignment, which reduces the number of additional state variables required in many cases. Second, in cases where conditional signals are sampled, it eliminates the need for state variable changes preceding output changes, which reduces overall input to output latency. Third, selection variables can easily be ordered to minimize the latency on a user-specified path, which is important for optimizing the performance of systems that use asynchronous components. We present extensive evaluations showing that, with only minimal optimization, the BBD-based synthesis gives comparable results in area with our previous exact two-level synthesis method. We also give a detailed example of the specified path optimization.","Title: Hardware compilation for FPGA-based configurable computing machines\nYear: 1999\n\nAbstract: Configurable computing machines are an emerging class of hybrid architectures where a field programmable gate array (FPGA) component is tightly coupled to a general-purpose microprocessor core. In these architectures, the FPGA component complements the general-purpose microprocessor by enabling a developer to construct application-specific gate-level structures on-demand while retaining the flexibility and rapid reconfigurability of a fully programmable solution. High computational performance can be achieved on the FPGA component by creating custom data paths, operators, and interconnection pathways that are dedicated to a given problem, thus enabling similar structural optimization benefits as ASICs. In this paper, we present a new programming environment for the development of applications on this new class of configurable computing machines. This environment enables developers to develop hybrid hardware/software applications in a common integrated development framework. In particular, the focus of this paper is on the hardware compilation part of the problem starting from a software-like algorithmic process-based specification. Traditionally, there has been a strong separation between software running on general-purpose programmable processors and dedicated hardware. Microprocessors can perform many different functions by providing a general mechanism to execute software. They can be programmed to perform different tasks, ranging from the execution of a word processor program to the processing of an audio stream. However, versatility comes at a price: applications implemented in software are usually much slower than their hardware counterparts. In contrast, application-specific hardware circuits provide precisely the functions needed for a specific task. Thus, they can be carefully tuned to the application, resulting in solutions that are often smaller, cheaper, faster, and more power efficient. The advent of field programmable gate arrays (FPGAs) offers an intriguing alternative. Like a general-purpose microprocessor, FPGAs can be dynamically reconfigured repeatedly to perform many different functions. However, like application-specific hardware, FPGAs can implement specific hardware structures that are tuned to the application. FPGAs consist of large arrays of reconfigurable logic blocks that can be reprogrammed to implement a specific gate-level customization. Thus, FPGAs can serve as a powerful adaptive computing engine. Indeed, a number of impressive results have been documented using reconfigurable logic for a number of applications, including RSA encryption [22], DNA sequencing [14], multi-standard video compression [22], automatic target recognition [21], and high energy physics [15], amongst others. Several recent advances have made the case for adaptive computing even more compelling. The densities and performance of FPGAs have increased by several orders of magnitude compared to earlier devices. Currently, FPGA devices with over 1M equivalent gates capacity running at 200MHz clock speeds are emerging. The dynamic reconfigurable times have also dramatically decreased despite the substantial increase in logic capacity. A new generation of devices is emerging that can be dynamically reconfigured at a rate of 250M gates/sec.","Title: Per-Flow Queue Management with Succinct Priority Indexing Structures for High Speed Packet Scheduling\nYear: 2013\n\nAbstract: Priority queues are essential building blocks for implementing advanced per-flow service disciplines and hierarchical quality-of-service at high-speed network links. Scalable priority queue implementation requires solutions to two fundamental problems. The first is to sort queue elements in real time at ever increasing line speeds (e.g., at OC-768 rates). The second is to store a huge number of packets (e.g., millions of packets). In this paper, we propose novel solutions by decomposing the problem into two parts, a succinct priority index (PI) in SRAM that can efficiently maintain a real-time sorting of priorities, coupled with a DRAM-based implementation of large packet buffers. In particular, we propose three related novel succinct PI data structures for implementing high-speed PIs: a PI, a counting priority index (CPI), and a pipelined counting priority index (pCPI). We show that all three structures can be very compactly implemented in SRAM using only $(\\Theta (U))$ space, where $(U)$ is the size of the universe required to implement the priority keys (time stamps). We also show that our proposed PI structures can be implemented very efficiently as well by leveraging hardware-optimized instructions that are readily available in modern 64-bit processors. The operations on the PI and CPI structures take $(\\Theta (\\log_W U))$ time complexity, where $(W)$ is the processor word length (i.e., $(W = 64)$). Alternatively, operations on the pCPI structure take amortized constant time with only $(\\Theta (\\log_W U))$ pipeline stages (e.g., only four pipeline stages for $(U = 16)$ million). Finally, we show the application of our proposed PI structures for the scalable management of large packet buffers at line speeds. The pCPI structure can be implemented efficiently in high-performance network processing applications such as advanced per-flow scheduling with quality-of-service guarantee.","Title: Design of heterogeneous ICs for mobile and personal communication systems\nYear: 1994\n\nAbstract: Mobile and personal communication systems form key market areas for the electronics industry of the nineties. Stringent requirements in terms of flexibility, performance and power dissipation, are driving the development of integrated circuits into the direction of heterogeneous single-chip solutions. New IC architectures are emerging which contain the core of a powerful programmable processor, complemented with dedicated hardware, memory and interface structures. In this tutorial we will discuss the real-life design of a heterogeneous IC for an industrial telecom application: a reconfigurable mobile terminal for satellite communication. Based on this practical design experience, we will subsequently discuss a methodology for the design of heterogeneous ICs. Design steps that will be addressed include: system specification and refinement, data path and communication synthesis, and code generation for embedded processor cores.","Title: Weighted Random Routing on Torus Networks\nYear: 2009\n\nAbstract: In this paper, we introduce a new closed-form oblivious routing algorithm called W2TURN that is worst-case throughput optimal for 2D-torus networks. W2TURN is based on a weighted random selection of paths that contain at most two turns. In terms of average hop count, W2TURN outperforms the best previously known closed-form worst-case throughput optimal routing algorithm called IVAL. In addition, we present a new optimal weighted random routing algorithm for rings called WRD.","Title: On The Efficient Implementation Of Pipelined Heaps For Network Processing\nYear: 2006\n\nAbstract: Priority queues are often used in many network processing applications. Applications include sophisticated per-flow scheduling for providing advanced Quality-of-Service (QoS) guarantees, fast packet buffer memory management, and exact maintanence of statistics counters for real-time network measurements. In all these applications, the priority queues used must operate at very high-speeds, e.g. at 40 Gbps rates and beyond. One widely used data structure for implementing priority queues is the heap data structure. However, the logarithmic time complexity of heap operations is often too slow for increasingly fast line rates. To achieve constant time complexity, the pipelined heap structure has been proposed. In this paper, we describe new architecture techniques for the efficient implementation of pipelined heaps. In particular, we focus on aggressive memory management and pipelining techniques.","Title: Synthesis of hazard-free multilevel logic under multiple-input changes from binary decision diagrams\nYear: 1994\n\nAbstract: We describe a new method for directly synthesizing a hazard-free multilevel logic implementation from a given logic specification. The method is based on free/ordered Binary Decision Diagrams (BDD's), and is naturally applicable to multiple-output logic functions. Given an incompletely-specified (multiple-output) Boolean function, the method produces a multilevel logic network that is hazard-free for a specified set of multiple-input changes. We assume an arbitrary (unbounded) gate and wire delay model under a pure delay (PD) assumption, we permit multiple-input changes, and we consider both static and dynamic hazards under the fundamental-mode assumption. Our framework is thus general and powerful. While it is not always possible to generate hazard-free implementations using our technique, we show that in some cases hazard-free multilevel implementations can be generated when hazard-free two-level representations cannot be found. This problem is generally regarded as a difficult problem and it has important applications in the field of asynchronous design. The method has been automated and applied to a number of examples","Title: Stream execution on wide-issue clustered VLIW architectures\nYear: 2007\n\nAbstract: This paper investigates the mapping of stream programs to wide-issue clustered VLIW processors so that designers can leverage their existing investments in VLIW-based platforms to harness the advantages of stream programming.","Title: Efficient verification using generalized partial order analysis\nYear: 1998\n\nAbstract: This paper presents a new formal method for the efficient verification of concurrent systems that are modeled using a safe Petri net representation. Our method generalizes upon partial-order methods to explore concurrently enabled conflicting paths simultaneously. We show that our method can achieve an exponential reduction in algorithmic complexity without resorting to an implicit enumeration approach.","Title: LEISURE: A Framework for Load-Balanced Network-Wide Traffic Measurement\nYear: 2011\n\nAbstract: Network-wide traffic measurement is of interest to network operators to uncover global network behavior for the management tasks of traffic accounting, debugging or troubleshooting, security, and traffic engineering. Increasingly, sophisticated network measurement tasks such as anomaly detection and security forensic analysis are requiring in-depth fine-grained flow-level measurements. However, performing in-depth per-flow measurements (e.g., detailed payload analysis) is often an expensive process. Given the fast-changing Internet traffic landscape and large traffic volume, a single monitor is not capable of accomplishing the measurement tasks for all applications of interest due to its resource constraint. Moreover, uncovering global network behavior requires network-wide traffic measurements at multiple monitors across the network since traffic measured at any single monitor only provides a partial view and may not be sufficient or accurate. These factors call for coordinated measurements among multiple distributed monitors. In this paper, we present a centralized optimization framework, LEISURE (Load-EqualIzed measurement), for load-balancing network measurement workloads across distributed monitors. Specifically, we consider various load-balancing problems under different objectives and study their extensions to support different deployment scenarios. We evaluate LEISURE via detailed simulations on Abilene and GEANT network traces to show that LEISURE can achieve much better load-balanced performance (e.g., 4.75X smaller peak workload and 70X smaller variance in workloads) across all coordinated monitors in comparison to naive solution (uniform assignment) to accomplish network-wide traffic measurement tasks.","Title: Frame-aggregated concurrent matching switch\nYear: 2007\n\nAbstract: Network operators need high-capacity router architectures that can offer scalability, provide throughput and performance guarantees, and maintain packet ordering. However, previous router architectures based on centralized crossbar-based architectures cannot scale to fast line rates and high port counts. Recently, a new scalable router architecture called the Concurrent Matching Switch (CMS)[5]was introduced that offers scalability by utilizing a fully distributed architecture based on two identical stages of fixed configuration meshes. It has been shown that fixed configuration meshes can be scaled to very fast line rates and highport counts via optical implementations.It has also been shown that the CMS architecture can achieve 100% through-put and packet ordering with only sequential hardware and O (1) amortized time complexity operations at each linecard. However, no delay performance guarantees have been shown for CMS. In this paper, we demonstrate a general delay performance guarantee for CMS.Based on this guarantee, we propose a novel frame-based CMS architecture that can achieve a performance guarantee of O (N log N)average packet delay, where N is the number of switch ports, while retaining scalability,throughput guarantees, packet ordering, and O (1) time complexity. This architecture improves upon the best previously-known average delay bound of O (N 2)given these switch properties. We further introduce several alternative frame-based CMS architectures.","Title: Robust Pipelined Memory System with Worst Case Performance Guarantee for Network Processing\nYear: 2012\n\nAbstract: Many network processing applications require wirespeed access to large data structures or a large amount of packet and flow-level data. Therefore, it is essential for the memory system of a router to be able to support both read and write accesses to such data at link speeds. As link speeds continue to increase, router designers are constantly grappling with the unfortunate trade-offs between the speed and cost of SRAM and DRAM. The capacity of SRAMs is woefully inadequate in many cases and it proves too costly to store large data structures entirely in SRAM, while DRAM is viewed as too slow for providing wirespeed updates at such high speed. In this paper, we analyze a robust pipelined memory architecture that can emulate an ideal SRAM by guaranteeing with very high probability that the output sequence produced by the pipelined memory architecture is the same as the one produced by an ideal SRAM under the same sequence of memory read and write operations, except time shifted by a fixed pipeline delay of Delta. Given a fixed pipeline delay abstraction, no interrupt mechanism is required to indicate when read data are ready or a write operation has completed, which greatly simplifies the use of the proposed solution. The design is based on the interleaving of DRAM banks together with the use of a reservation table that serves in part as a data cache. In contrast to prior interleaved memory solutions, our design is robust under all memory access patterns, including adversarial ones, which we demonstrate through a rigorous worst case theoretical analysis using a combination of convex ordering and large deviation theory.","Title: Hierarchical optimization of asynchronous circuits\nYear: 1995\n\nAbstract: Many asynchronous designs are naturally specified and implemented hierarchically as an interconnection of separate asyn- chronous modules that operate concurrently and communicate with each other. This paper is concerned with the problem of synthesizing such hierarchically defined systems. When the individual components are synthesized and implemented separately, it is desirable to take into account the degrees of freedom that arise from the interactions with the other components and from the specification. Specifically, we consider how one can find the set of implementations that can be \"correctly sub- stituted\" for a component in the system while preserving the behavior of the total system. The notion of correct substitution is formally de- fined for a hierarchical network of possibly non-deterministic modules and a new solution framework based on trace theory is presented to compute and represent this complete set of correct substitutions. We show that the complete set can be captured by a single trace structure using the notion of a \"maximal trace structure\". We indicate how asyn- chronous synthesis methods may be applied to explore the solution space e.g. to generate a delay-insensitive implementation. II NTRODUCTION The role of asynchronous design is gaining importance due to increasing difficulties with problems like clock skew and power dissipation. In many design scenarios, the design is most natu- rally described and implemented hierarchically as a network of separate asynchronous modules that operate concurrently and communicate with each other. Hierarchical representations are especially important when the design is compiled from a high- level language. Also, implementation constraints may force their physical implementations to be separated. Indeed, real-life de- signs show that many asynchronous applications are inherently distributive and highly interactive, thus requiring methods to handle them. When optimizing each individual component sep- arately, it is desirable to take into account the degrees of freedom that arise from the interactions with the other components and from the specification. This is analogous to the problem of op- timizing hierarchically combinational and synchronous circuits, which has been studied extensively. For the design of asynchronous control circuits, the ex- isting literature describes a number of automated algorith- mic approaches based on Petri net and state machine models (2, 4, 10, 11, 15, 20, 21, 22, 23). These works have focussed mainly on the synthesis and optimization of individual asynchronous modules without considering the optimization freedom avail- able in optimizing concurrent behavior. Methods based on mod- els of communicating processes have also been extensively stud- ied in the literature (1, 3, 13, 18). These methods are mainly based on syntax-directed translation techniques. Though these meth- ods can effectively model concurrent behavior, they also have","Title: Sizing and verification of communication buffers for communicating processes\nYear: 1993\n\nAbstract: No abstract available.","Title: A system design methodology for software/hardware co-development of telecommunication network applications\nYear: 1996\n\nAbstract: In this paper, we describe a system design methodology for the concurrent development of hybrid software/hardware systems for telecom network applications. This methodology is based on the results of an investigation and evaluation of an actual industrial system design application for ATM-based broadband networks. The aim of this methodology is to provide an integrated design flow from system specification to implementation","Title: Custom networks-on-chip architectures with multicast routing\nYear: 2009\n\nAbstract: In this paper, we consider the problem of synthesizing custom networks-on-chip (NoC) architectures that are optimized for a given application. We consider both unicast and multicast traffic flows in the input specification. Multicast traffic flows are used in a variety of applications, and their direct support with only replication of packets at optimal bifurcation points rather than full end-to-end replication can significantly reduce network contention and resource requirements. Our problem formulation is based on the decomposition of the problem into the inter-related steps of finding good flow partitions, deriving a good physical network topology for each group in the partition, and providing an optimized network implementation for the derived topologies. Our solutions may be comprised of multiple custom networks, each interconnecting a subset of communicating modules. We propose several algorithms that can systematically examine different flow partitions, and we propose Rectilinear-Steiner-Tree (RST)-based algorithms for generating efficient network topologies. Our design flow integrates floorplanning, and our solutions consider deadlock-free routing. Experimental results on a variety of NoC benchmarks showed that our synthesis results can on average achieve a 4.82 times reduction in power consumption over different mesh implementations on unicast benchmarks and a 1.92 times reduction in power consumption on multicast benchmarks. Significant improvements in performance were also achieved, with an average of 2.92 times reduction in hop count on unicast benchmarks and 1.82 times reduction in hop count on multicast benchmarks. To further gauge the effectiveness of our heuristic algorithms, we also implemented an exact algorithm that enumerates all distinct set partitions. For the benchmarks where exact results could be obtained, our algorithms on average can achieve results within 3 % of exact results, but with much shorter execution times.","Title: A New Worst-Case Throughput Bound for Oblivious Routing in Odd Radix Mesh Network\nYear: 2013\n\nAbstract: 1/2 network capacity is often believed to be the limit of worst-case throughput for mesh networks. However, this letter provides a new worst-case throughput bound, which is higher than 1/2 network capacity, for odd radix two-dimensional mesh networks. In addition, we propose a routing algorithm called U2TURN that can achieve this worst-case throughput bound. U2TURN considers all routing paths with at most 2 turns and distributes the traffic loads uniformly in both X and Y dimensions. Theoretical analysis and simulation results show that U2TURN outperforms existing routing algorithms in worst-case throughput. Moreover, U2TURN achieves good average-throughput at the expense of approximately 1.5x minimal average hop count.","Title: A block-based reservation architecture for the implementation of large packet buffers\nYear: 2009\n\nAbstract: DRAM is typically needed to implement large packet buffers, but DRAM devices have worst-case random access latencies that are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into three categories: prefetching-based [1], randomization-based [2], and reservation-based [3]. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. Each class of architectures has its own benefits. For router architectures where the departure times of packets can be deterministically calculated before the packets are inserted into the packet buffer, the reservation-based approach has the nice property that in-time packet retrievals can be guaranteed. Reservation-based architectures work by constructive placement of packets and scheduling of memory operations based on the departure times of packets.","Title: Randomized Partially-Minimal Routing on Three-Dimensional Mesh Networks\nYear: 2008\n\nAbstract: This letter presents a new oblivious routing algorithm for 3D mesh networks called Randomized Partially- Minimal (RPM) routing that provably achieves optimal worstcase throughput for 3D meshes when the network radix k is even and within a factor of 1/k2 of optimal when k is odd. Although this optimality result has been achieved with the minimal routing algorithm O1TURN [9] for the 2D case, the worst-case throughput of O1TURN degrades tremendously in higher dimensions. Other existing routing algorithms suffer from either poor worst-case throughput (DOR [10], ROMM [8]) or poor latency (VAL [14]). RPM on the other hand achieves near optimal worst-case and good average-case throughput as well as good latency performance.","Title: Design of application-specific 3D Networks-on-Chip architectures.\nYear: 2008\n\nAbstract: The increasing viability of three dimensional (3D) silicon integration technology has opened new opportunities for chip design innovations, including the prospect of extending emerging Systems-on-Chip (SoC) design paradigms based on Networks-on-Chip (NoC) interconnection architectures to 3D chip designs. In this paper, we consider the problem of designing application-specific 3D-NoC architectures that are optimized for a given application. We present novel 3D-NoC synthesis algorithms that make use of accurate power and delay models for 3D wiring with through-silicon vias. In particular, we present a very efficient 3D-NoC synthesis algorithm called Ripup-Reroute-and-Router-Merging (RRRM), that is based on a rip-up and reroute formulation for routing flows and a router merging procedure for network optimization. Experimental results on 3D-NoC design cases show that our synthesis results can on average achieve a 74% reduction in power consumption and a 17% reduction in hop count over regular 3D mesh implementations and a 52% reduction in power consumption and a 17% reduction in hop count over optimized 3D mesh implementations.","Title: A strategy for real-time kernel support in application-specific HW/SW embedded architectures\nYear: 1996\n\nAbstract: Heterogeneous embedded multiprocessor architectures are becom- ing more prominent as a key design solution to today's microelec- tronics design problems. These application-specific architectures in- tegrate multiple software programmable processors and dedicated hardwarecomponents together on to a single cost-efficient IC. In con- trast to general-purpose computer systems, embedded systems are designed and optimized to provide specific functionality, using pos- sibly a combination of different classes of processors (e.g. DSPs, mi- crocontrollers) from different vendors. While these customized het- erogeneous multiprocessor architectures offer designers new possi- bilities to tradeoff programmability, processing performance, power dissipation, and design turnaround time, there is currently a lack of tools to support the programming of these architectures. In this pa- per, we consider the problem of providing real-time kernel support for managing the concurrent software tasks that are distributed over a set of processorsin an application-specific multiprocessorarchitec- ture. This is complementary to current research activities that aim to provide efficient retargetable code generation (8, 11, 10) for a broad range of embedded processors.","Title: Destination-based congestion awareness for adaptive routing in 2D mesh networks\nYear: 2013\n\nAbstract: The choice of routing algorithm plays a vital role in the performance of on-chip interconnection networks. Adaptive routing is appealing because it offers better latency and throughput than oblivious routing, especially under nonuniform and bursty traffic. The performance of an adaptive routing algorithm is determined by its ability to accurately estimate congestion in the network. In this regard, maintaining global congestion state using a separate monitoring network offers better congestion visibility into distant parts of the network compared to solutions relying only on local congestion. However, the main challenge in designing such routing schemes is to keep the logic and bandwidth overhead as low as possible to fit into the tight power, area, and delay budgets of on-chip routers. In this article, we propose a minimal destination-based adaptive routing strategy (DAR), where every node estimates the delay to every other node in the network, and routing decisions are based on these per-destination delay estimates. DAR outperforms Regional Congestion Awareness (RCA), the best previously known adaptive routing algorithm that uses nonlocal congestion state. The performance improvement is brought about by maintaining fine-grained per-destination delay estimates in DAR that are more accurate than regional congestion metrics measured in RCA. The increased accuracy is a consequence of the fact that the per-destination delay estimates are not corrupted by congestion on links outside the admissible routing paths to the destination. A scalable version of DAR, referred to as SDAR, is also proposed for minimizing the overheads associated with DAR in large network topologies. We show that DAR outperforms local adaptive routing by up to 79% and RCA by up to 58% in terms of latency on SPLASH-2 benchmarks. DAR and SDAR also outperform existing adaptive and oblivious routing algorithms in latency and throughput under synthetic traffic patterns on 8×8 and 16times;16 mesh topologies, respectively.","Title: An Oblivious Routing Algorithm for 3D Mesh Networks to Achieve a New Worst-Case Throughput Bound\nYear: 2012\n\nAbstract: 1/2 network capacity is often believed to be the limit of worst-case throughput for three-dimension (3D) mesh networks. However, this paper provides a new worst-case throughput bound, which is higher than 1/2 network capacity, for odd radix 3D mesh networks. In addition, we propose a routing algorithm called uniform solo-minimal (USM) routing that can achieve this new worst-case throughput bound in odd radix mesh networks. For the even radix case, we prove that USM achieves the optimal worst-case throughput, namely, half of network capacity. USM considers all routing paths with at most one dimensional minimal-distance routing and distributes the traffic loads uniformly to other two left dimensions. Theoretical analysis and simulation results show that USM outperforms existing routing algorithms in worst-case throughput. Moreover, USM achieves good average-throughput and performs very well under different traffic matrices at the expense of $({5}/{3})\\\\times$ minimal average hop count.","Title: Enhanced metamodeling techniques for high-dimensional IC design estimation problems\nYear: 2013\n\nAbstract: Accurate estimators of key design metrics (power, area, delay, etc.) are increasingly required to achieve IC cost reductions in system-level through physical layout optimizations. At the same time, identifying physical or analytical models of design metrics has become very challenging due to interactions among many parameters that span technology, architecture and implementation. Metamodeling techniques can simplify this problem by deriving surrogate models from samples of actual implementation data. However, the use of metamodeling techniques in IC design estimation is still in its infancy, and practitioners need more systematic understanding. In this work, we study the accuracy of metamodeling techniques across several axes: (1) low- and high-dimensional estimation problems, (2) sampling strategies, (3) sample sizes, and (4) accuracy metrics. To help obtain more general conclusions, we study these axes for three very distinct chip design estimation problems: (1) area and power of networks-on-chip routers, (2) delay and output slew of standard cells under power delivery network noise, and (3) wirelength and buffer area of clock trees. Our results show that (1) adaptive sampling can effectively reduce the sample size required to derive surrogate models by up to 64% (or, increase estimation accuracy by up to 77%) compared with Latin hypercube sampling; (2) for low-dimensional problems, Gaussian process-based models can be 1.5x more accurate than tree-based models, whereas for high-dimensional problems, tree-based models can be up to 6x more accurate than Gaussian process-based models; and (3) a variant of weighted surrogate modeling [7], which we call hybrid surrogate modeling, can improve estimation accuracy by up to 3x. Finally, to aid architects, design teams, and CAD developers in selection of the appropriate metamodeling techniques, we propose guidelines based on the insights gained from our studies.","Title: Guest Editors' Introduction: Special Issue on Quality-of-Service.\nYear: 2013\n\nAbstract: The papers in this special issue focus on quality of service in the network and services management sectors.","Title: Compiling concurrent programs for embedded sequential execution\nYear: 2007\n\nAbstract: Embedded applications are often more naturally modeled as a set of concurrent tasks, but yet they are often implemented using a single embedded processor. Traditionally, run-time operating systems have been used to simulate concurrency by timesharing the underlying processor and to facilitate inter-process communication amongst the concurrent tasks. However, this run-time approach to multi-tasking and inter-process communication can often introduce significant overhead to execution times and memory requirements, prohibitive in many cases for embedded applications where processor and memory resources are scarce. In this paper, we present compilation techniques that can statically resolve concurrency at compile-time so that the resulting code produced can be sequentially executed on an embedded processor without the need for a run-time scheduler. Our techniques are based on a novel Petri net theoretic framework. In particular, we show how a concurrent program specification can be transformed into an intermediate Petri net representation. We then show how the intermediate Petri net may be statically scheduled to produce a sequential state machine model that can be sequentially executed directly on an embedded processor without a run-time operating system. In practice, this technique produces efficient results. However, theoretically, it is possible for the resulting state machine to become very large, resulting in code explosion. To circumvent this limitation, we describe a compositional approach that can scale well to large applications and is immune to code explosion.","Title: DRAM-Based Statistics Counter Array Architecture With Performance Guarantee\nYear: 2012\n\nAbstract: The problem of efficiently maintaining a large number (say millions) of statistics counters that need to be updated at very high speeds (e.g., 40 Gb/s) has received considerable research attention in recent years. This problem arises in a variety of router management and data streaming applications where large arrays of counters are used to track various network statistics and implement various counting sketches. It proves too costly to store such large counter arrays entirely in SRAM, while DRAM is viewed as too slow for providing wirespeed updates at such high line rates. In particular, we propose a DRAM-based counter architecture that can effectively maintain wirespeed updates to large counter arrays. The proposed approach is based on the observation that modern commodity DRAM architectures, driven by aggressive performance roadmaps for consumer applications, such as video games, have advanced architecture features that can be exploited to make a DRAM-based solution practical. In particular, we propose a randomized DRAM architecture that can harness the performance of modern commodity DRAM offerings by interleaving counter updates to multiple memory banks. The proposed architecture makes use of a simple randomization scheme, a small cache, and small request queues to statistically guarantee a near-perfect load-balancing of counter updates to the DRAM banks. The statistical guarantee of the proposed randomized scheme is proven using a novel combination of convex ordering and large deviation theory. Our proposed counter scheme can support arbitrary increments and decrements at wirespeed, and they can support different number representations, including both integer and floating point number representations.","Title: Weighted random oblivious routing on torus networks\nYear: 2009\n\nAbstract: Torus, mesh, and flattened butterfly networks have all been considered as candidate architectures for on-chip interconnection networks. In this paper, we study the problem of optimal oblivious routing for one of these architecture classes, namely, the torus network. We introduce a new closed-form oblivious routing algorithm called W2TURN that is worst-case throughput optimal for 2D-torus networks. W2TURN is based on a weighted random selection of paths that contain at most two turns. Restricting the maximum number of turns in routing paths to just two results in a simple deadlock-free implementation of W2TURN. In terms of average hop count, W2TURN outperforms the best previously known closed-form worst-case throughput optimal routing algorithm called IVAL [14]. We also provide another routing algorithm based on the weighted random selection of paths with at most two turns called I2TURN and show that it is equivalent to IVAL. However, I2TURN eliminates the need for loop removal at runtime and provides a closed-form analytical expression for evaluating the average hop count. The latter enables us to demonstrate analytically that W2TURN strictly outperforms IVAL (and I2TURN) in average hop count. Finally, we present a new optimal weighted random routing algorithm for rings called WRD (Weighted Random Direction). WRD provides a closed form expression for the the optimal distribution of traffic along the minimal and non-minimal directions in a ring topology to achieve minimum average hop count under maximum worst-case throughput.","Title: Stream Execution on Embedded Wide-Issue Clustered VLIW Architectures\nYear: 2008\n\nAbstract: Very long instruction word- (VLIW-) based processors have become widely adopted as a basic building block in modern System-on-Chip designs. Advances in clustered VLIW architectures have extended the scalability of the VLIW architecture paradigm to a large number of functional units and very-wide-issue widths. A central challenge with wide-issue clustered VLIW architecture is the availability of programming and automated compiler methods that can fully utilize the available computational resources. Existing compilation approaches for clustered-VLIW architectures are based on extensions of previously developed scheduling algorithms that primarily focus on the maximization of instruction-level parallelism (ILP). However, many applications do not have sufficient ILP to fully utilize a large number of functional units. On the other hand, many applications in digital communications and multimedia processing exhibit enormous amounts of data-level parallelism (DLP). For these applications, the streaming programming paradigm has been developed to explicitly expose coarse-grained data-level parallelism as well as the locality of communication between coarse-grained computation kernels. In this paper, we investigate the mapping of stream programs to wide-issue clustered VLIW processors. Our work enables designers to leverage their existing investments in VLIW-based architecture platforms to harness the advantages of the stream programming paradigm.","Title: A High-Throughput Distributed Shared-Buffer NoC Router\nYear: 2009\n\nAbstract: Microarchitectural configurations of buffers in routers have a significant impact on the overall performance of an on-chip network (NoC). This buffering can be at the inputs or the outputs of a router, corresponding to an input-buffered router (IBR) or an output-buffered router (OBR). OBRs are attractive because they have higher throughput and lower queuing delays under high loads than IBRs. However, a direct implementation of OBRs requires a router speedup equal to the number of ports, making such a design prohibitive given the aggressive clocking and power budgets of most NoC applications. In this letter, we propose a new router design that aims to emulate an OBR practically based on a distributed shared-buffer (DSB) router architecture. We introduce innovations to address the unique constraints of NoCs, including efficient pipelining and novel flow control. Our DSB design can achieve significantly higher bandwidth at saturation, with an improvement of up to 20% when compared to a state-of-the-art pipelined IBR with the same amount of buffering, and our proposed microarchitecture can achieve up to 94% of the ideal saturation throughput.","Title: Measurement-Aware Monitor Placement and Routing: A Joint Optimization Approach for Network-Wide Measurements.\nYear: 2012\n\nAbstract: Network-wide traffic measurement is important for various network management tasks, ranging from traffic accounting, traffic engineering, network troubleshooting to security. Previous research in this area has focused on either deriving better monitor placement strategies for fixed routing, or strategically routing traffic sub-populations over existing deployed monitors to maximize the measurement...","Title: Proactive surge protection: a defense mechanism for bandwidth-based attacks\nYear: 2009\n\nAbstract: Large-scale bandwidth-based distributed denial-of-service (DDoS) attacks can quickly knock out substantial parts of a network before reactive defenses can respond. Even traffic flows that are not under direct attack can suffer significant collateral damage if these flows pass through links that are common to attack routes. Given the existence today of large botnets with more than a hundred thousand bots, the potential for a large-scale coordinated attack exists, especially given the prevalence of high-speed Internet access. This paper presents a Proactive Surge Protection (PSP) mechanism that aims to provide a broad first line of defense against DDoS attacks. The approach aims to minimize collateral damage by providing bandwidth isolation between traffic flows. This isolation is achieved through a combination of traffic measurements, bandwidth allocation of network resources, metering and tagging of packets at the network perimeter, and preferential dropping of packets inside the network. The proposed solution is readily deployable using existing router mechanisms and does not rely on any unauthenticated packet header information. Thus the approach is resilient to evading attack schemes that launch many seemingly legitimate TCP connections with spoofed IP addresses and port numbers. Finally, our extensive evaluation results across two large commercial backbone networks, using both distributed and targeted attack scenarios, show that up to 95.5% of the network could suffer collateral damage without protection, but our solution was able to significantly reduce the amount of collateral damage by up to 97.58% in terms of the number of packets dropped and 90.36% in terms of the number of flows with packet loss. Furthermore, we show that PSP can maintain low packet loss rates even when the intensity of attacks is increased significantly.","Title: Design of a High-Throughput Distributed Shared-Buffer NoC Router\nYear: 2010\n\nAbstract: Router microarchitecture plays a central role in the performance of an on-chip network (NoC). Buffers are needed in routers to house incoming flits which cannot be immediately forwarded due to contention. This buffering can be done at the inputs or the outputs of a router, corresponding to an input-buffered router (IBR) or an output-buffered router (OBR). OBRs are attractive because they can sustain higher throughputs and have lower queuing delays under high loads than IBRs. However, a direct implementation of an OBR requires a router speedup equal to the number of ports, making such a design prohibitive under aggressive clocking needs and limited power budgets of most NoC applications. In this paper, we propose a new router design that aims to emulate an OBR practically, based on a distributed shared-buffer (DSB) router architecture. We introduce innovations to address the unique constraints of NoCs, including efficient pipelining and novel flow-control. We also present practical DSB configurations that can reduce the power overhead with negligible degradation in performance. The proposed DSB router achieves up to 19% higher throughput on synthetic traffic and reduces packet latency by 60% on average for SPLASH-2 benchmarks with high contention, compared to a state-of-art pipelined IBR. On average, the saturation throughput of DSB routers is within 10% of the theoretically ideal saturation throughput under the synthetic workloads evaluated.","Title: Designing efficient codes for synchronization error channels\nYear: 2011\n\nAbstract: For communications and networking channels, coding techniques are widely used to correct errors in corrupted messages. The \"Quality of Protection\" (QoP) that can be provided via error correction directly affects the \"Quality of Service\" (QoS) experienced by users. The errors are commonly assumed to be substitution or erasure errors. Such systems rely on perfect synchronization so that no bit is deleted and no extra bit is inserted. However, in a system without the presence of perfect synchronization, special coding algorithms may be required to correct potential insertion or deletion errors in transmitted messages. Especially for systems suffering from frequent loss of synchronization, packets may require many retransmissions to guarantee reliable communication. Such schemes may become too expensive to be practical. In this paper, we propose a new synchronization channel error model based on the observations from current communication systems. In this model, the channel introduces at most t synchronization errors in each run of the transmitted sequence. We present run-length limited permutation codes capable of correcting synchronization errors based on this channel error model. Compared to previously developed codes, our codes have the advantage of correcting frequent synchronization errors, and therefore they are suitable for disruptive network channels that suffer severe synchronization failures.","Title: The interleaved matching switch architecture\nYear: 2009\n\nAbstract: Operators need routers to provide service guarantees such as guaranteed flow rates and fairness among flows, so as to support traffic engineering and real-time traffic. However, current centralized input-queued router architectures cannot scale to fast line rates while providing these service guarantees. On the other hand, while load-balanced switch architectures that rely on two identical stages of fixed-configuration switches appear to be an effective way to scale Internet routers to very high capacities, there is currently no practical and scalable solution for providing service guarantees in these architectures. In this paper, we introduce the interleaved matching switch (IMS) architecture, which relies on a novel approach to provide service guarantees using load-balanced switches. The approach is based on emulating a Birkhoff-von Neumann switch with a load-balanced switch architecture and is applicable to any known admissible traffic. We show that service guarantees, 100% throughput, and packet ordering can be achieved with O(1) online complexity. In cases where fixed frame sizes are applicable, we also present an efficient offline frame-based decomposition method. More generally, we show that the IMS architecture can be used to emulate any input queued or combined input-output queued switch, leveraging a large body of known results for ensuring stability.","Title: Control resynthesis for control-dominated asynchronous designs.\nYear: 1996\n\nAbstract: Syntax directed translation based compilation from high-level concurrent programs has matured significantly over the past few years. They have been applied to significant designs in the domains of digital signal processing and microprocessor designs. For data-path dominated designs, like those found in digital signal processing applications, syntax directed translation approaches have been shown to generate efficient asynchronous implementations. However, for control-dominated designs where the data processing parts play a relatively minor role, we believe the solutions produced by pure syntax directed translation methods may be significantly improved. In this paper, we consider the problem of resynthesizing the control parts of the syntax directed translation solutions by means of STG based algorithmic synthesis approaches. This involves a strategy for partitioning between the control and data processing parts, algorithms for reconstructing the STGs from the control partitions, and a strategy for resynthesizing these reconstructed STGs using existing STG-based synthesis approaches. We show with a realistic design experiment that our control resynthesis approach can offer significant improvements over pure syntax directed translation solutions.","Title: The Concurrent Matching Switch Architecture\nYear: 2010\n\nAbstract: Network operators need high-capacity router architectures that can offer scalability, provide throughput guarantees, and maintain packet ordering. However, current centralized crossbar-based architectures cannot scale to fast line rates and high port counts. On the other hand, while load-balanced switch architectures that rely on two identical stages of fixed configuration meshes appear to be an effective way to scale Internet routers to very high capacities, they incur a large worst-case packet reordering that is at best quadratic to the switch size. In this paper, we introduce the concurrent matching switch (CMS) architecture, which also uses two identical stages of fixed configuration meshes with the same scalability properties as current load-balanced routers. However, by adopting a novel contention-resolution architecture that is scalable and distributed, the CMS architecture enforces packet ordering throughout the switch. Using the CMS architecture, we show that scalability, 100% throughput, packet ordering, and O(1) amortized time complexity with sequential hardware per linecard can all be achieved. We further demonstrate a delay analysis for the CMS architecture.","Title: Synthesis of concurrent system interface modules with automatic protocol conversion generation\nYear: 1994\n\nAbstract: We describe a new high-level compiler called Integral for designing system interface modules. The input is a high-level concurrent algorithmic specification that can model complex concurrent control flow, logical and arithmetic computations, abstract communication, and low-level behavior. For abstract communication between two communicating modules that obey different I/O protocols, the necessary protocol conversion behaviors are automatically synthesized using a Petri net theoretic approach. We present a synthesis trajectory that can synthesize the necessary hardware resources, control circuitry, and protocol conversion behaviors for implementing system interface modules.","Title: An on-chip global broadcast network design with equalized transmission lines in the 1024-core era\nYear: 2012\n\nAbstract: Based on current trends in multicore scaling, chips with 1024 cores may be available within the next decade. For such number of cores, cache coherence becomes a critical challenge because of the broadcasting operation. For the conventional electrical mesh interconnect network, broadcasting common data to all the cores is difficult to perform efficiently. In this paper, we developed a high-throughput, low-latency and power-efficient equalized dense transmission line (T-line) structure tailored for efficient global broadcasting. Moreover, we propose a hierarchical architecture and an efficient physical structure for 1024-core communication. Evaluation results show high performance of our solution.","Title: A generalized signal transition graph model for specification of complex interfaces\nYear: 1994\n\nAbstract: This paper introduces a new Generalized Signal Transition Graph model for specifying complex mixed asynchronous/synchronous circuits, as found in system-level interfaces. The goal has been to develop extensions that make it possible to model mixed asynchronous/synchronous and arbitration behavior. A number of key extensions have been developed that makes the model much more widely applicable to industrial designs. The extensions include Boolean guards, the introduction of level semantics that make it possible to describe “events” in terms of both signal transitions as well as “signal levels”, and the semantic extensions for describing don't care and undefined behavior. The latter extensions make it possible to model synchronous finite state machines using an asynchronous model, hence permitting the specification of mixed asynchronous/synchronous behavior. The proposed Generalized Signal Transition Graph Model is free from the restrictions of the previous models such as liveness, safeness, and free-choice requirements, and permits general Petri-net structures that may include multiple tokens in a place as long as the resulting state graph is bounded and has a consistent state assignment. A key aspect of the generalizations is that all the extensions are defined at the state graph level","Title: On the impact of traffic statistics on quality of service for networks on chip\nYear: 2005\n\nAbstract: Packet switched networks on chip (NoC) architectures have been proposed as a solution to the global interconnect problem in the nanoscale systems on chip (SoC) design era. An important design consideration for NoC, is silicon cost. Towards the goal of keeping the NoC simple, we pose the following question: under what traffic conditions will quality of service (QoS) be provided without the added complexity of an explicit QoS mechanism? In this paper, we take the first step towards answering this question by empirically analyzing different combinations of traffic patterns and injection processes. Specifically, we analyze the effects of different traffic on latency under two cases: (1) an NoC with no QoS mechanism (i.e. without distinction among different classes of service); and (2) an NoC with the simplest distinction into two classes of service: guaranteed service and best effort.","Title: Basic gate implementation of speed-independent circuits\nYear: 1994\n\nAbstract: Existing methods for synthesis of speed- independent circuits under unbounded delay model have diffi- culties in combining the generality of formal approach with the practicality of the implementation architectures used at the logic level. This paper presents a characteristic property of the state graph specification, called Monotonous Cover requirement, im- plying its hazard-free implementation within the standard struc- ture of a two-level SOP logic and a row of latches. The overall synthesis procedure ensures satisfiability of this condition by ap- plying the generalised state assignment approach. I INTRODUCTION The design of asynchronous circuitry is a difficult task since circuit malfunction can occur during execution if it is not free of hazards. One approach is based on bounded gate/wire de- lay assumptions and relies on delay information to eliminate hazards (7), which means the implementation is not robust to delay variations due to differences in process technologies or noise and temperature variations. In this paper, we consider the problem of producing speed-independent asynchronous circuits using only basic gates such as AND-gates, OR-gates, and asynchronous latches. Speed-independence means that the circuit will work correctly regardless of the individual gate delays. This is known as the unbounded gate delay model. It assumes that the wires can also have arbitrary delays, but the skew of all wire delays at multiple fanouts be negligible (less than the minimum gate delay). Speed-independent re- alizations are particularly attractive because they can tolerate delay variations that are inevitable when migrating to different process technologies or even with a known technology un- der process or temperature variations. This also implies that speed-independent modules can easily be replaced whenever a higher performance process technology becomes available. There has been considerable research on the theory and automated synthesis of speed-independent circuits using com- plex gates (3, 8, 12). This theory is based on the assumptions that each non-input signal of a correct specification, which is either a Signal Transition Graph or semimodular State Graph, is implemented with a single complex gate and that this com- plex gate contains no internal hazards. It has been shown that the requirement of Complete State Coding(CSC) is the necessary and sufficient condition for such a complex gate implementation (3). However, it is often the case that the re- quired combinational logic functions are too complex to have single complex gate implementations from a standard library. Thus, researchers have investigated the problem of synthesiz- ing speed-independent circuits that assumes only the availabil- ity of basic gates such as AND-gates and OR-gates. However,","Title: A Scalable Switch for Service Guarantees\nYear: 2005\n\nAbstract: Operators need routers to provide service guarantees such as guaranteed flow rates and fairness among flows, so as to support real-time traffic and traffic engineering. However, current centralized input-queued router architectures cannot scale to fast line rates while providing these service guarantees. On the other hand, while load-balanced switch architectures that rely on two identical stages of fixed configuration switches appear to be an effective way to scale Internet routers to very high capacities, there is currently no practical and scalable solution for providing service guarantees in these architectures. In this paper, we introduce the interleaved matching switch (IMS) architecture, which relies on a novel approach to provide service guarantees using load-balanced switches. The approach is based on emulating a Birkhoff-von Neumann switch with a load-balanced switch architecture and is applicable to any admissible traffic. In cases where fixed frame sizes are applicable, we also present an efficient frame-based decomposition method. More generally, we show that the IMS architecture can be used to emulate any input queued or combined input-output queued switch.","Title: Minimizing collateral damage by proactive surge protection\nYear: 2007\n\nAbstract: Existing mechanisms for defending against distributed denial-of-service (DDoS) attacks are generally reactive in nature. However, the onset of large-scale bandwidth-based attacks can occur suddenly, potentially knocking out substantial parts of a network before reactive defenses can respond. Even for traffic flows that are not under direct attack, significant collateral damage will result if these flows pass through links that are common to attack routes. This paper presents a proactive-surge-protection (PSP) mechanism that aims to provide a broad first line of defense against DDoS attacks. Our solution aims to minimize collateral damage by providing bandwidth isolation between traffic flows. This isolation is achieved through a combination of traffic forecasting, proportional allocation of network capacity, metering and tagging of packets at the network perimeter, and preferential dropping of packets inside the network. Our solution is readily deployable using existing router mechanisms. Simulations across three large backbone networks show that up to 95.5% of the network could suffer collateral damage without protection, but our solution was able to reduce the amount of collateral damage by 60.5-97.8%, even with a coarse-grained forecasting scheme.","Title: Constructing application-specific heterogeneous embedded architectures from custom HW/SW applications\nYear: 1996\n\nAbstract: Deep sub-micron processing technologies have enabled the imple- mentation of new application-specific embedded architecturesthat in- tegrate multiple software programmable processors (e.g. DSPs, mi- crocontrollers) and dedicated hardware components together onto a single cost-efficient IC. These application-specific architectures are emerging as a key design solution to today's microelectronics design problems, which are being driven by emerging applications in the ar- eas of wireless communication, broadband networking, and mu ltime- dia computing. However, the construction of these customized hetero- geneous multiprocessor architectures, while ensuring that the hard- ware and software parts communicate correctly, is a tremendously difficult and highly error proned task with little or no tool s upport. In this paper, we present a solution to this embedded architecture co- synthesis problem based on an orchestrated combination of architec- tural strategies, parameterized libraries, and software tool support.","Title: Power estimation methods for sequential logic circuits\nYear: 1995\n\nAbstract: Recently developed methods for power estimation have primarily focused on combinational logic. We present a framework for the efficient and accurate estimation of average power dissipation in sequential circuits. Switching activity is the primary cause of power dissipation in CMOS circuits. Accurate switching activity estimation for sequential circuits is considerably more difficult than that for combinational circuits, because the probability of the circuit being in each of its possible states has to be calculated. The Chapman-Kolmogorov equations can be used to compute the exact state probabilities in steady state. However, this method requires the solution of a linear system of equations of size 2/sup N/ where N is the number of flip-flops in the machine. We describe a comprehensive framework for exact and approximate switching activity estimation in a sequential circuit. The basic computation step is the solution of a nonlinear system of equations which is derived directly from a logic realization of the sequential machine. Increasing the number of variables or the number of equations in the system results in increased accuracy. For a wide variety of examples, we show that the approximation scheme is within 1-3% of the exact method, but is orders of magnitude faster for large circuits. Previous sequential switching activity estimation methods can have significantly greater inaccuracies.<>","Title: Derivation of formal representations from process-based specification and implementation models\nYear: 1997\n\nAbstract: In this paper we present a method that allows to observe and control the emulation of communicating systems consisting of hardware and software parts. The approach provides the ability to set breakpoints in either technology without breaking the protocol or loosing data. Systems may contain several software and hardware processes. Each process runs in a separate debugger while the presented approach provides the necessary synchronization between the processes that precludes loss of data at the communication interfaces due to breakpoints. Therefore it allows to continue the operation after a breakpoint which is essential for interactive debugging.","Title: Fast and Scalable Priority Queue Architecture for High-Speed Network Switches\nYear: 2000\n\nAbstract: In this paper, we present a fast and scalable pipelined priority queue architecture for use in high-performance switches with support for fine-grained quality of service (QoS) guarantees. Priority queues are used to implement highest-priority-first scheduling policies. Our hardware ar- chitecture is based on a new data structure called a Pipelined heap, or P-heap for short. This data structure enables the pipelining of the enqueue and dequeue operations, thereby allowing these operations to execute in essentially constant time. In addition to being very fast, the architecture also scales very well to a large number of priority levels and to large queue sizes. We give a detailed description of this new data structure, the asso- ciated algorithms and the corresponding hardware implementation. We have implemented this new architecture using a 0.35 micron CMOS tech- nology. Our current implementation can support 10 Gb/s connections with over 4 billion priority levels .","Title: Reservation-Based Packet Bufferswith Deterministic Packet Departures\nYear: 2014\n\nAbstract: High-performance routers need to temporarily store a large number of packets in response to congestion. DRAM is typically needed to implement large packet buffers, but the worst-case random access latencies of DRAM devices are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into two categories: prefetching-based and randomization-based. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. In this paper, we describe novel reservation-based packet buffer architectures with interleaved memories that take advantage of the known packet departure times to achieve simplicity and determinism. The number of interleaved DRAM banks required to implement the proposed packet buffer architectures is independent of the number of logical queues, yet the proposed architectures can achieve the performance of an SRAM implementation. Our reservation-based solutions are scalable to growing packet storage requirements in routers while matching increasing line rates.","Title: Embedded architecture co-synthesis and system integration\nYear: 1996\n\nAbstract: Embedded system architectures comprising of software programmable components (e.g. DSP, ASIP, and micro-controller cores) and customized hardware co-processors, integrated into a single cost-efficient VLSI chip, are emerging as a key solution to today's microelectronics design problems. This trend is being driven by new emerging applications in the areas of wireless communication, high-speed optical networking, and multimedia computing. A key problem confronted by embedded system designers today is the rapid prototyping of application-specific embedded system architectures where different combinations of programmable processors and hardware components must be integrated together, while ensuring that the hardware and software parts communicate correctly. In this paper, we present a solution to this embedded architecture co-synthesis and system integration problem based on an orchestrated combination of architectural strategies, parameterized libraries, and software CAD tools","Title: A novel 3D layer-multiplexed on-chip network\nYear: 2009\n\nAbstract: Recently, a near-optimal oblivious routing algorithm for 3D mesh networks called Randomized Partially-Minimal (RPM) routing was proposed [12], which works by load-balancing traffic across vertical layers and routing minimally on each horizontal layer. It achieves optimal worst-case throughput when the network radix k is even and within a factor of 1/k2 of optimal when k is odd, and it achieves significantly lower latencies than Valiant routing [18], the best previously known optimal worst-case throughput algorithm. This paper presents a novel layer-multiplexed (LM) architecture for 3D on-chip networks that exploits the optimality of RPM together with the short inter-layer wiring delays enabled in 3D technology. The LM architecture replaces the one-layer-per-hop routing in a 3D mesh with simpler vertical demultiplexing and multiplexing structures. The proposed LM architecture can achieve the same worst-case throughput as a 3D mesh by adapting RPM routing to the LM architecture. However, the LM architecture consumes 27% less power, occupies 27% less area, attains 14.5% higher average throughput, and achieves 33% lower worst-case hop count for a symmetric 4x4x4 mesh topology. On an asymmetric 8 x 8 x 4 mesh, the LM architecture achieves comparable average-case throughput to a 3D mesh, but consumes 26% less power, takes up 27% less area and attains 20% lower worst-case hop count.","Title: Birkhoff-von Neumann switching with statistical traffic profiles\nYear: 2010\n\nAbstract: Offline scheduling is attractive when the traffic profile is known a priori since the complexity of online scheduling is largely removed. Given any admissible rate matrix @L=(@l\"i\"j), Birkhoff-von Neumann decomposition offers a quasi-offline scheduling strategy that can provide a service rate of at least @l\"i\"j for each flow (i,j) without internal speedup. This paper extends the Birkhoff-von Neumann switching strategy to consider traffic profiles in which the traffic demands are specified as statistical distributions rather than fixed rates.","Title: Design of High-Speed Packet Switch with Fine-Grained Quality-of-Service Guarantees\nYear: 2000\n\nAbstract: We present a new input-queued switch architecture designed to support deadline-ordered scheduling at extremely high-speeds. In particular, deadline-ordered scheduling is enabled through a combination of hardware-based sorted priority queues called P-heaps and a round-robin crossbar scheduler. The priority queues are implemented using a novel scalable pipelined heap-based architecture. Using a 0.35 micron CMOS standard-cell technology, we demonstrate a 32-port switch capable of sustaining 10 Gb/s line rates.","Title: Flow Graph Balancing for Minimizing the Required Memory Bandwidth\nYear: 1996\n\nAbstract: In this paper we present the problem of flow graph balancing for minimizing the required memory bandwidth. Our goal is to minimize the required memory bandwidth within the given cycle budget by adding ordering constraints to the flow graph. This allows the subsequent memory allocation and assignment tasks to come up with a cheaper memory architecture with less memories and memory ports. The effect of flow graph balancing is shown on an example. We show that it is important to take into account which data is being accessed in parallel, instead of only considering the number of simultaneous memory accesses. This leads to the optimization of a conflict graph.","Title: Joint multicast routing and network design optimisation for networks-on-chip\nYear: 2009\n\nAbstract: In this study, we consider the problem of synthesising custom networks-on-chip (NoC) architectures that are optimised for a given application. Both unicast and multicast traffic flows are considered in the input specification. We formulate the joint multicast routing and network design problem using a rip-up and reroute procedure, where each multicast routing step is formulated as a minimum direct...","Title: Rank-indexed hashing: A compact construction of Bloom filters and variants\nYear: 2008\n\nAbstract: Bloom filter and its variants have found widespread use in many networking applications. For these applications, minimizing storage cost is paramount as these filters often need to be implemented using scarce and costly (on-chip) SRAM. Besides supporting membership queries, Bloom filters have been generalized to support deletions and the encoding of information. Although a standard Bloom filter construction has proven to be extremely space-efficient, it is unnecessarily costly when generalized. Alternative constructions based on storing fingerprints in hash tables have been proposed that offer the same functionality as some Bloom filter variants, but using less space. In this paper, we propose a new fingerprint hash table construction called Rank-Indexed Hashing that can achieve very compact representations. A rank-indexed hashing construction that offers the same functionality as a counting Bloom filter can be achieved with a factor of three or more in space savings even for a false positive probability of just 1%. Even for a basic Bloom filter function that only supports membership queries, a rank-indexed hashing construction requires less space for a false positive probability as high as 0.1%, which is significant since a standard Bloom filter construction is widely regarded as extremely space-efficient for approximate membership problems.","Title: DRAM is plenty fast for wirespeed statistics counting\nYear: 2008\n\nAbstract: Per-flow network measurement at Internet backbone links requires the efficient maintanence of large arrays of statistics counters at very high speeds (e.g. 40 Gb/s). The prevailing view is that SRAM is too expensive for implementing large counter arrays, but DRAM is too slow for providing wirespeed updates. This view is the main premise of a number of hybrid SRAM/DRAM architectural proposals [2, 3, 4, 5] that still require substantial amounts of SRAM for large arrays. In this paper, we present a contrarian view that modern commodity DRAM architectures, driven by aggressive performance roadmaps for consumer applications (e.g. video games), have advanced architecture features that can be exploited to make DRAM solutions practical. We describe two such schemes that can harness the performance of these DRAM offerings by enabling the interleaving of counter updates to multiple memory banks. These counter schemes are the first to support arbitrary increments and decrements for either integer or floating point number representations at wirespeed. We believe our preliminary success with the use of DRAM schemes for wirespeed statistics counting opens the possibilities for broader research opportunities to generalize the proposed ideas for other network measurement functions.","Title: LEISURE: Load-Balanced Network-Wide Traffic Measurement and Monitor Placement\nYear: 2015\n\nAbstract: Network-wide traffic measurement is of interest to network operators to uncover global network behavior for the management tasks of traffic accounting, debugging or troubleshooting, security, and traffic engineering. Increasingly, sophisticated network measurement tasks such as anomaly detection and security forensic analysis are requiring in-depth fine-grained flow-level measurements. However, performing in-depth per-flow measurements (e.g., detailed payload analysis) is often an expensive process. Given the fast-changing Internet traffic landscape and large traffic volume, a single monitor is not capable of accomplishing the measurement tasks for all applications of interest due to its resource constraint. Moreover, uncovering global network behavior requires network-wide traffic measurements at multiple monitors across the network since traffic measured at any single monitor only provides a partial view and may not be sufficient or accurate. These factors call for coordinated measurements among multiple distributed monitors. In this paper, we present a centralized optimization framework, LEISURE (Load-EqualIzed meaSUREment), for load-balancing network measurement workloads across distributed monitors. Specifically, we consider various load-balancing problems under different objectives and study their extensions to support both fixed and flexible monitor deployment scenarios. We formulate the latter flexible monitor deployment case as an MILP (Mixed Integer Linear Programming) problem and propose several heuristic algorithms to approximate the optimal solution and reduce the computation complexity. We evaluate LEISURE via detailed simulations on Abilene and GEANT network traces to show that LEISURE can achieve much better load-balanced performance (e.g., 4.75× smaller peak workload and 70× smaller variance in workloads) across all coordinated monitors in comparison to a naive solution (uniform assignment) to accomplish network-wide traffic measure- ent tasks under the fixed monitor deployment scenario. We also show that under the flexible monitor deployment setting, our heuristic solutions can achieve almost the same load-balancing performance as the optimal solution while reducing the computation times by a factor up to 22.5× in Abilene and 800× in GEANT.","Title: ORION3.0: A Comprehensive NoC Router Estimation Tool\nYear: 2015\n\nAbstract: Networks-on-Chip (NoCs) are increasingly used in many-core architectures. ORION2.0 [1] is a widely adopted NoC power and area estimation tool, but its estimation models can have large errors (up to 185%) versus actual implementations. We present ORION3.0, an open-source tool whose parametric and non-parametric modeling methodologies fundamentally differ from ORION2.0 logic template-based approaches in that the estimation models are derived from actual physical implementation data. When compared with actual implementations, ORION3.0 models achieve average estimation errors of no more than 9.3% across microarchitecture, implementation, and operational parameters as well as multiple router RTL generators. A comprehensive suite of these methodologies has been implemented in ORION3.0 [2].","Title: Revisiting State Blow-Up: Automatically Building Augmented-FA While Preserving Functional Equivalence\nYear: 2014\n\nAbstract: Regular expression matching, a central task in deep packet inspection and other networking applications, has been traditionally implemented through finite automata. Thanks to their limited per-character processing and memory bandwidth requirements, deterministic finite automata (DFA) are a natural choice for memory-based implementations. In the presence of large datasets of complex patterns, however, DFA suffer from the well-known state explosion problem. Specifically, state explosion can take place during DFA generation when the considered patterns contain bounded and unbounded repetitions of wildcards or large character sets. Several alternative FA representations have been proposed to address this problem. However, these proposals all suffer from one or more of the following problems: some can avoid state explosion only on datasets of limited size and complexity; some have prohibitive worst-case memory bandwidth requirements or processing time; and some can only guarantee functional equivalence for restricted classes of regular expressions and require the user to manually filter out unsupported patterns. In this work we propose JFA, a finite automation that uses state variables to avoid state explosion, and is functionally equivalent to the corresponding DFA. Functional equivalence is guaranteed by construction without requiring user intervention. We also provide optimization techniques to both limit the amount of state variables required and provide a lower bound for the JFA traversal time.","Title: Sprinklers: A Randomized Variable-Size Striping Approach to Reordering-Free Load-Balanced Switching.\nYear: 2014\n\nAbstract: Internet traffic continues to grow exponentially, calling for switches that can scale well in both size and speed. While load-balanced switches can achieve such scalability, they suffer from a fundamental packet reordering problem. Existing proposals either suffer from poor worst-case packet delays or require sophisticated matching mechanisms. In this paper, we propose a new family of stable load-balanced switches called \"Sprinklers\" that has comparable implementation cost and performance as the baseline load-balanced switch, but yet can guarantee packet ordering. The main idea is to force all packets within the same virtual output queue (VOQ) to traverse the same ``fat path'' through the switch, so that packet reordering cannot occur. At the core of Sprinklers are two key innovations: a randomized way to determine the \"fat path\" for each VOQ, and a way to determine its \"fatness\" roughly in proportion to the rate of the VOQ. These innovations enable Sprinklers to achieve near-perfect load-balancing under arbitrary admissible traffic. Proving this property rigorously using novel worst-case large deviation techniques is another key contribution of this work.","Title: Minimization of symbolic relations\nYear: 1990\n\nAbstract: The problem of minimizing symbolic relations is addressed. The relevance of this problem in the field of optimal encoding is shown by examples. A binate covering formulation of the optimization problems involved is given, for which several algorithms are available. A novel method is proposed which is based on binary decision diagrams (BDDs) and the authors show how the covering problem can be solved in linear time in that case.<>","Title: Implicit manipulation of equivalence classes using binary decision diagrams\nYear: 1991\n\nAbstract: A novel representation called an equivalence class characterization function is defined. It can implicitly represent all equivalence classes with a compact characteristic function that will have at most n outputs. Using binary decision diagrams (BDDs) and the concept of the equivalence class characterization function, very large problem instances can be represented. For manipulating equivalence classes efficiently, a Boolean operator called a compatible projection operator is proposed. Conceptually, the compatible projection operator is used to uniquely select a single element from each equivalence class to characterize the class. In manipulating equivalence classes, the compatible projection operator is used to implicitly derive an encoding function from the equivalence relation that encodes the equivalence class information symbolically. An efficient implementation is described based on BDDs that is applied to very large problem instances","Title: Symbolic hazard-free minimization and encoding of asynchronous finite state machines\nYear: 1995\n\nAbstract: This paper presents an automated method for the synthesis of multiple-input-change (MIC) asynchronous state machines. Asynchronous state machine design is subtle since, unlike synchronous synthesis, logic must be implemented without hazards, and state codes must be chosen carefully to avoid critical races. We formulate and solve an optimal hazard-free and critical race-free encoding problem for a class of MIC asynchronous state machines called burst-mode. Analogous to a paradigm successfully used for the optimal encoding of synchronous machines, the problem is formulated as an input encoding problem. Implementations are targeted to sum-of-product realizations. We believe this is the first general method for the optimal encoding of hazard-free MIC asynchronous state machines under a generalized fundamental mode of operation. Results indicate that improved solutions are produced, ranging up to 17% improvement.","Title: Efficient partial enumeration for timing analysis of asynchronous systems\nYear: 1996\n\nAbstract: This paper presents an efficient method for the timing verification of concurrent systems, modeled as labeled Timed Petri nets. The verification problems we consider re- quire us to analyze the system's reachable behaviors under the specified time delays. Ourgeometric timing analysis algo- rithm improves over existing ones by enumerating the state space onlypartially. The algorithm relies on a concept called pre-mature firingand a new, extended notion of clocks with a negative age. We have tested the fully automated proce- dure on a number of examples. Experimental results obtained on highly concurrent Petri nets with more than 6000 nodes and reachable states show that the proposed method can drastically reduce computational cost. I Introduction","Title: Hardware/software co-design of digital telecommunication systems\nYear: 1997\n\nAbstract: We reflect on the nature of digital telecommunication systems. We argue that these systems require, by nature, a heterogeneous specification and an implementation with heterogeneous architectural styles. CoWare is a hardware/software co-design environment based on a data model that allows to specify, simulate, and synthesize heterogeneous hardware/software architectures from a heterogeneous specification. CoWare is based on the principle of encapsulation of existing hardware and software compilers and special attention is paid to the interactive synthesis of hardware/software and hardware/hardware interfaces. The principles of CoWare are illustrated by the design process of a spread-spectrum receiver for a pager system","Title: Externally hazard-free implementations of asynchronous control circuits\nYear: 1997\n\nAbstract: We present a new sum-of-product-based asynchronous architecture, called the N-SHOT architecture, that operates correctly under internal hazardous responses and guarantees hazard-freeness at the observable noninput signals. We formally prove that within this architecture, a very wide class of semimodular state graphs with input choices (either distributive or nondistributive) that satisfy the complete state coding property always admit a correct implementation, As with synchronous circuits, we permit internal hazards in the combinational logic core, which means that we can make use of conventional combinational logic minimization methods to produce the sum-of-product implementation. This represents a significant departure from most existing methods that require the combinational logic to be hazard-free and are mainly valid for distributive behaviors, We also present optimizations for this architecture which are related to state graph properties","Title: A Methodology for Efficient Estimation of Switching Activity in Sequential Logic Circuits\nYear: 1994\n\nAbstract: We describe a computationally efficient scheme to approximate average switching activity in sequential circuits which requires the solution of a non-linear system of equations of size N, where the variables correspond to state line probabilities. We show that the approximation method is within 3% of the exact Chapman-Kolmogorov method, but is orders of magnitude faster for large circuits. Previous sequential switching activity estimation methods can have significantly greater inaccuracies.","Title: Fast Buffer Memory with Deterministic Packet Departures\nYear: 2006\n\nAbstract: High-performance routers need to store temporarily a large number of packets in response to congestion. DRAM is typically used to implement the needed packet buffers, but DRAM devices are too slow to match the bandwidth requirements. To bridge the bandwidth gap, a number of hybrid SRAM/DRAM packet buffer architectures have been proposed (S. Iyer and N. Mckeown, 2002) (S. Kumar et al., 2005). These packet buffer architectures assume a very general model where the buffer consists of many logically separated FIFO queues that may be accessed in random order. For example, virtual output queues (VOQs) are used in crossbar routers, where each VOQ corresponds to a logical queue corresponding to a particular output. Depending on the scheduling algorithm used, the access pattern to these logical queues may indeed be at random. However, for a number of router architectures, this worst-case random access assumption is unnecessary since packet departure times are deterministic. One architecture is the switch-memory-switch router architecture (A. Prakash et al., 2002) (S. Iyer et al., 2002) that efficiently mimics an output queueing switch. Another architecture is the load-balanced router architecture (C.S. Chang et al., 2002) (I. Keslassy et al., 2003) that has interesting scalability properties. In these architectures, for best-effort routing, the departure times of packets can be deterministically calculated before inserting packets into packet buffers. In this paper, we describe a novel packet buffer architecture based on interleaved memories that takes advantage of the known packet departure times to achieve simplicity and determinism. The number of interleaved DRAM banks required to implement the proposed packet buffer architecture is independent of the number of logical queues, yet the proposed architecture can achieve the performance of an SRAM implementation","Title: Near-optimal oblivious routing on three-dimensional mesh networks\nYear: 2008\n\nAbstract: The increasing viability of three dimensional (3D) silicon integration technology has opened new opportunities for chip architecture innovations. One direction is in the extension of two-dimensional (2D) mesh-based tiled chip-multiprocessor architectures into three dimensions. In this paper, we focus on efficient routing algorithms for such 3D mesh networks. As in the case of 2D mesh networks, throughput and latency are important design metrics for routing algorithms. Existing routing algorithms suffer from either poor worst-case throughput (DOR , ROMM) or poor latency (VAL). Although the minimal routing algorithm O1TURN proposed in already achieves near-optimal worst-case throughput for the 2D case, the optimality result does not extend to higher dimensions. For 3D and higher dimensional meshes, the worst-case throughput of O1TURN degrades tremendously. The main contribution of this paper is the design of a new oblivious routing algorithm for 3D mesh networks called randomized partially-minimal (RPM) routing. RPM provably achieves optimal worst-case throughput for 3D meshes when the network radix k is even and within a factor of 1/k2 of optimal worst-case throughput when k is odd. RPM also outperforms VAL, DOR, ROMM, and O1TURN in average-case throughput by 33.3%, 111%, 47%, and 30%, respectively when averaged over one million random traffic patterns on an 8 times 8 times 8 topology. Finally, whereas VAL achieves optimal worst-case throughput at a penalty factor of 2 in average latency over DOR, RPM achieves (near) optimal worst-case throughput with a much smaller factor of 1.33. In practice, the average latency of RPM is expected to be closer to minimal routing because 3D mesh networks are not expected to be symmetric in 3D chip designs. The number of available device layers is expected to be much less than the number of processor tiles that can be placed along an edge of a device layer. For practical asymmetric 3D mesh configurations, the average laten- - cy of RPM reduces to just a factor of 1.11 of DOR.","Title: Randomized Partially-Minimal Routing: Near-Optimal Oblivious Routing for 3-D Mesh Networks\nYear: 2012\n\nAbstract: The increasing viability of 3-D silicon integration technology has opened new opportunities for chip architecture innovations. One direction is in the extension of 2-D mesh-based tiled chip-multiprocessor architectures into three dimensions. This paper focuses on efficient routing algorithms for such 3-D mesh networks. Existing routing algorithms suffer from either poor worst-case throughput (DOR, ROMM) or poor latency (VAL). Although the minimal routing algorithm O1TURN proposed in already achieves near-optimal worst-case throughput for 2-D mesh networks, the optimality result does not extend to higher dimensions. For 3-D and higher dimensional meshes, the worst-case throughput of O1TURN degrades tremendously. The main contribution of this paper is a new oblivious routing algorithm for 3-D mesh networks called randomized partially-minimal (RPM) routing. RPM provably achieves optimal worst-case throughput for 3-D meshes when the network radix k is even and within a factor of 1/k2 of optimal worst-case throughput when k is odd. Finally, whereas VAL achieves optimal worst-case throughput at a penalty factor of 2 in average latency over DOR, RPM achieves (near) optimal worst-case throughput with a much smaller factor of 1.33. For practical asymmetric 3-D mesh configurations where the number of device layers are fewer than the number of tiles along the edge of a layer, the average latency of RPM reduces to just a factor of 1.11 to 1.19 of DOR. Additionally, a variant of RPM called randomized minimal first (RMF) routing is proposed, which leverages the inherent load-balancing properties of the network traffic to further reduce packet latency without compromising throughput.","Title: Optimal multi-path routing and bandwidth allocation under utility max-min fairness\nYear: 2009\n\nAbstract: An important goal of bandwidth allocation is to maximize the utilization of network resources while sharing the resources in a fair manner among network flows. To strike a bal- ance between fairness and throughput, a widely studied criterion in the network community is the notion of max-min fairness. However, the majority of work on max-min fairness has been limited to the case where the routing of flows has already been defined and this routing is usually based on a single fixed routing path for each flow. In this paper, we consider the more general problem in which the routing of flows, possibly over multiple paths per flow, is an optimization parameter in the bandwidth allocation problem. Our goal is to determine a routing assignment for each flow so that the bandwidth allocation achieves optimal utility max-min fairness with respect to all feasible routings of flows. We present evaluations of our proposed multi-path utility max-min fair allocation algorithms on a statistical traffic engi- neering application to show that significantly higher minimum utility can be achieved when multi-path routing is considered simultaneously with bandwidth allocation under utility max- min fairness, and this higher minimum utility corresponds to significant application performance improvements.","Title: Efficient trace-driven metaheuristics for optimization of networks-on-chip configurations\nYear: 2010\n\nAbstract: As industry moves towards many-core chips, networks-on-chip (NoCs) are emerging as a scalable communication fabric for interconnecting the cores. With increasing core counts, there is a corresponding increase in communication demands in multi-core designs to facilitate high core utilization, and a consequent critical need for high-performance NoCs. Another megatrend in advanced technologies is that power has become the most critical design constraint. In this paper, we focus on trace-driven virtual channel (VC) allocation in application-specific NoCs. We propose a new significant VC failure metric to capture the impact of VCs on network performance and efficiently drive NoC optimization. Our proposed metaheuristics achieve up to 38% reduction in the number of VCs under a given average packet latency constraint. In addition, compared to a recently proposed trace-driven VC allocation approach [13], we obtain up to an O(|L|) speedup, where |L| is total number of links in the network, with no degradation in the quality of results.","Title: Improved on-chip router analytical power and area modeling\nYear: 2010\n\nAbstract: Over the course of this decade, uniprocessor chips have given way to multi-core chips which have become the primary building blocks of today's computer systems. The presence of multiple cores on a chip shifts the focus from computation to communication as a key bottleneck to achieving performance improvements. As industry moves towards many-core chips, networks-on-chip (NoCs) are emerging as the scalable fabric for interconnecting the cores. With power now the first-order design constraint, early-stage estimation of NoC power has become crucially important. Existing power models (e.g., ORION 2.0 [12], Xpipes [7], etc.) are based on certain router microarchitecture and circuit implementation. Therefore, when validated against different NoC prototypes - different router implementations -- we saw significant deviation (up to 40% on average) that can lead to erroneous NoC design choices. This has prompted our development of a new, accurate architecture- and circuit implementation-independent router power and area modeling methodology with complete portability across existing NoC component libraries. Also, validation against a range of implemented router designs confirms substantial improvement in accuracy over existing models.","Title: Frame-based multicast switching\nYear: 2010\n\nAbstract: This letter considers the multicast scheduling problem for the case where the average rates of flows are known and a fixed frame size is applicable. We present a frame-based decomposition method for computing offline a recurring schedule that can guarantee the specified flow rates with minimum internal speedup, if any. We consider both the no-splitting case, where a multicast cell must be transferred to all its destinations in a single time slot, and the fanout-splitting case, where a multicast cell may take multiple time slots to transfer to all its destinations, transferring only to a subset of its destinations each time.","Title: High-dimensional metamodeling for prediction of clock tree synthesis outcomes\nYear: 2013\n\nAbstract: Clock tree synthesis (CTS) is a key aspect of on-chip interconnect, and major consumer of IC power and physical design resources. In modern sub-28nm tools and flows, it has become exceptionally difficult to satisfy skew, insertion delay and transition time constraints within power and area budgets, in part because commercial tools (with their many knobs) have become highly complex. This complexity, along with the complicated structure of real-world CTS instances (hierarchy, dividers, etc.) and floorplan contexts (aspect ratios, obstacles, etc.) make it very difficult to predict skew, power and other important metrics of CTS outcomes. In this work, we study CTS estimation in the high-dimensional parameter space of instance constraints and floorplan contexts. Using two leading commercial CTS tools as our testbed, we develop predictors, classifiers and “field of use” characterizations that can enable IC design teams to achieve required CTS solution quality through understanding of appropriate parameter subspaces. Our hierarchical hybrid surrogate modeling approach mitigates challenges of parameter multicollinearity in high dimensions. It achieves, e.g., worst-case estimation errors of 13% in contrast to 30% errors in [17]. We demonstrate use of a 94%-accurate “oracle” classifier and estimation models to predictably achieve CTS outcomes that meet specified constraints and target metrics.","Title: A Simple Mechanism For Throttling High-Bandwidth Flows\nYear: 2008\n\nAbstract: This letter presents BREATHe, a simple packet dropping scheme for identifying and throttling unresponsive or misbehaving highbandwidth flows during times of congestion. BREATHe is different from the existing active queue management techniques in that it uses heavy-hitter set analysis to identify highbandwidth flows rather than sampling or rate estimation. Specifically, BREATHe uses heavy-hitter set analysis to detect highbandwidth flows that exceed some target rate rlimit and preferentially drop packets from these flows. We show that the proposed mechanism is effective at throttling high-bandwidth flows using a small amount of state and low-complexity operation. Copyright (C) 2008 C.-W. Chang and B. Lin.","Title: Modeling and optimization of hierarchical synchronous circuits\nYear: 1995\n\nAbstract: Synchronous designs are often described and implemented hierarchically as a network of interacting finite state machines. When the individual components are synthesized and implemented separately, it is desirable to take into account the degrees of freedom that arise from the interactions with the other components and from the specification. Specifically, we consider the problem of finding the complete set of implementations that can be correctly substituted for a component in a system without changing the behavior of the total system. In this paper, a synchronous trace set model is proposed to tackle this problem. The unambiguous way in which this model describes synchronous behavior provides us with a general method to model interacting finite state machines. We show that a single synchronous trace set can be used to characterize all possible substitutions in a correct substitution problem. We give a necessary notion of progress that permits us to choose a correct one from this set, or to show that no solution exists. We provide results of an implicit implementation of our approach applied to benchmarks ranging from small to very large state machines. These results show the feasibility of the proposed methods.","Title: System design tools for broadband telecom network applications\nYear: 1996\n\nAbstract: Outlines a design methodology for the design of hybrid software/hardware systems that are typically found in telecom network applications. This methodology is based on the results of an investigation and evaluation of an actual industrial system application for ATM (Asynchronous Transfer Mode) based broadband networks at Alcatel Bell. As a result of this investigation, we have developed a system design methodology based on a concurrent object-oriented programming model as the system behavioral specification formalism. For implementation, we provide automated design tools for transforming the system level model into the traditional levels of design entries for hardware and software implementation. In particular, conventional C++ and VHDL models are generated for the parts of the system to be implemented in software and hardware, respectively. New system-level synthesis functionalities are required to achieve these automations. It is important to note that traditional hardware and software design methods, mostly commercially available, are used in our design flow, thereby not reinventing new solutions where adequate ones already exist. The work outlined in this presentation is embodied in a system design compiler called Matisse.","Title: Single-tier virtual queuing: an efficacious memory controller architecture for MPSoCs with multiple realtime cores.\nYear: 2016\n\nAbstract: In heterogeneous MPSoCs, memory interference between the CPU and realtime cores is a critical impediment to system performance. Previous memory schedulers adopt the classic two-tier queuing system, but unfortunately the use of two-tier queuing deteriorates the QoS of scheduling policies. In this paper, we propose the Single-Tier Virtual Queuing (STVQ) memory controller for efficacious QoS-aware scheduling. The STVQ memory controller maintains single-tier transaction queues and employs separable allocation for transaction scheduling with high scalability. A multi-source realtime scheduling algorithm is further presented. The STVQ controller achieves up to 13.9% less CPU IPC slowdown than previous schedulers with no frame rate penalty on realtime cores.","Title: Safe Randomized Load-Balanced Switching by Diffusing Extra Loads.\nYear: 2017\n\nAbstract: Load-balanced switch architectures are known to be scalable in both size and speed, which is of interest due to the continued exponential growth in Internet traffic. However, the main drawback of load-balanced switches is that packets can depart out of order from the switch. Randomized load-balancing of application flows by means of hashing on the packet header is a well-known simple solution to this packet reordering problem in which all packets belonging to the same application flow are routed through the same intermediate port and hence the same path through the switch. Unfortunately, this method of load-balancing can lead to instability, depending on the mix of flow sizes and durations in the group of flows that gets randomly assigned to route through the same intermediate port. In this paper, we show that the randomized load-balancing of application flows can be enhanced to provably guarantee both stability and packet ordering by extending the approach with safety mechanisms that can uniformly diffuse packets across the switch whenever there is a build-up of packets waiting to route through some intermediate port. Although simple and intuitive, our experimental results show that our extended randomized load-balancing approach outperforms existing load-balanced switch architectures.","Title: Sharing a global on-chip transmission line medium without centralized scheduling\nYear: 2016\n\nAbstract: We consider the design of a shared global on-chip communication medium using repeated equalized transmission lines (RETLs). Our design overcomes a number of limitations with previously proposed shared global mediums based on transmission lines. Prior solutions require wide-pitch transmission lines that occupy considerable area, do not support multicast or broadcast operations, and employ centralized schedulers that are difficult to scale. In this paper, we propose a novel design based on RETLs that utilizes thin transmission lines that require a much narrower pitch, about 6x narrower in comparison to previously proposed wide-pitch-based designs. In addition, our design supports multicast and broadcast operations, which are critical for the implementation of cache coherency protocols. Moreover, our design is based on fully distributed arbitration protocols that can achieve very high throughput and bandwidth utilization, but are simple to implement. We demonstrate a design using 32 lanes of 20 Gb/s differential RETLs that provides 640 Gb/s aggregated throughput and enables communications between any on-chip cores in under two core clock cycles, including multicast and broadcast communications. Given the narrow pitch of RETLs, our design can easily scale to multiple terabits per seconds with additional lanes. Simulation results with both synthetic and real benchmarks with up to 64 parallel threads demonstrate that our proposed distributed solutions are capable of achieving near ideal throughput.","Title: A Single-Tier Virtual Queuing Memory Controller Architecture for Heterogeneous MPSoCs.\nYear: 2017\n\nAbstract: Heterogeneous MPSoCs typically integrate diverse cores, including application CPUs, GPUs, and HD coders. These cores commonly share an off-chip memory to save cost and energy, but their memory accesses often interfere with each other, leading to undesirable consequences like a slowdown of application performance or a failure to sustain real-time performance. The memory controller plays a central role in meeting the QoS needs of real-time cores while maximizing CPU performance. Previous QoS-aware memory controllers are based on a classic two-tier queuing architecture that buffers memory transactions at the first tier, followed by a second tier that buffers translated DRAM commands. In these designs, QoS-aware policies are used to schedule competing transactions at the first stage, but the translated DRAM commands are served in FIFO order at the second stage. Unfortunately, once the scheduled transactions have been forwarded to the command stage, newly arriving transactions that may be more critical cannot be served ahead of those translated commands that are already queued at the second stage. To address this, we propose a scalable memory controller architecture based on single-tier virtual queuing (STVQ) that maintains a single tier of request queues and employs an efficacious scheduler that considers both QoS requirements and DRAM bank states. In comparison with previous QoS-aware memory controllers, the proposed STVQ memory controller reduces CPU slowdown by up to 13.9% while satisfying all frame rate requirements. We propose further optimizations that can significantly increase row-buffer hits by up to 66.2% and reduce memory latency by up to 19.8%.","Title: Improving Backpressure-based Adaptive Routing via Incremental Expansion of Routing Choices.\nYear: 2017\n\nAbstract: Backpressure-based adaptive routing algorithms have been studied extensively in the literature. Although backpressure-based adaptive routing algorithms have been shown to be network-wide throughput optimal, they typically have poor delay performance under light or moderate loads because packets may be sent over unnecessarily long routes. Further, backpressure-based algorithms have required every node to compute differential backlogs for every destination queue with the corresponding destination queue at every adjacent node. This computation is expensive given the large number of possible pairwise differential backlogs and requires many exchanges of backlog information between adjacent nodes. In this paper, we propose new backpressure-based adaptive routing algorithms that only use shortest-path routes to destinations when they are sufficient to accommodate the given traffic load, but the proposed algorithms will incrementally expand routing choices as needed to accommodate increasing traffic loads. We show analytically by means of fluid analysis that the proposed algorithms retain network-wide throughput optimality, and we show empirically by means of simulations that our proposed algorithms provide substantial improvements in delay performance. Our evaluations further show that in practice, our approach dramatically reduces the number of pairwise differential backlogs that have to be computed and the amount of corresponding backlog information that has to be exchanged because routing choices are only incrementally expanded as needed.","Title: Harvesting Row-Buffer Hits via Orchestrated Last-Level Cache and DRAM Scheduling for Heterogeneous Multicore Systems\nYear: 2018\n\nAbstract: In heterogeneous multicore systems, the memory subsystem, including the last-level cache and DRAM, is widely shared among the CPU, the GPU, and the real-time cores. Due to their distinct memory traffic patterns, heterogeneous cores result in more frequent cache misses at the last-level cache. As cache misses travel through the memory subsystem, two schedulers are involved for the last-level cache and DRAM, respectively. Prior studies treated the scheduling of the last-level cache and DRAM as independent stages. However, with no orchestration and limited visibility of memory traffic, neither scheduling stage is able to ensure optimal scheduling decisions for memory efficiency. Unnecessary precharges and row activations happen in DRAM when the memory scheduler is ignorant of incoming cache misses, and DRAM row-buffer states are invisible to the last-level cache. In this article, we propose a unified memory controller for the the last-level cache and DRAM with orchestrated schedulers. The memory scheduler harvests row-buffer hit opportunities in cache request buffers during spare time without inducing significant implementation cost. We further introduce a dynamic orchestrated scheduling policy to improve memory efficiency while achieving target CPU IPC. Extensive evaluations show that the proposed controller improves the total memory bandwidth of DRAM by 16.8% on average and saves DRAM energy by up to 29.7% while achieving comparable CPU IPCs. With the dynamic scheduling policy, the unified controller achieves the same IPC as the conventional design and increases DRAM bandwidth by 9.2%. In addition, we explore the potential of the proposed memory controller to attain improvements on both memory bandwidth and CPU IPC.","Title: SARA: Self-Aware Resource Allocation for Heterogeneous MPSoCs.\nYear: 2018\n\nAbstract: In modern heterogeneous MPSoCs, the management of shared memory resources is crucial in delivering end-to-end QoS. Previous frameworks have either focused on singular QoS targets or the allocation of partitionable resources among CPU applications at relatively slow timescales. However, heterogeneous MPSoCs typically require instant response from the memory system where most resources cannot be partitioned. Moreover, the health of different cores in a heterogeneous MPSoC is often measured by diverse performance objectives. In this work, we propose the Self-Aware Resource Allocation (SARA) framework for heterogeneous MPSoCs. Priority-based adaptation allows cores to use different target performance and self-monitor their own intrinsic health. In response, the system allocates non-partitionable resources based on priorities. The proposed framework meets a diverse range of QoS demands from heterogeneous cores.","Title: Network optimization for unified packet and circuit switched networks\nYear: 2018\n\nAbstract: Internet traffic continues to grow relentlessly, driven largely by increasingly high resolution video content. Although studies have shown that the majority of packets processed by Internet routers are pass-through traffic, they nonetheless have to be queued and routed at every hop in current networks, which unnecessarily adds substantial delays and processing costs. Such pass-through traffic can be better circuit-switched through the underlying optical transport network by means of pre-established circuits, which is possible in a unified packet and circuit switched network. In this paper, we propose a novel convex optimization framework based on a new destination-based multicommodity flow formulation for the allocation of circuits in such unified networks. In particular, we consider two deployment settings, one based on real-time traffic monitoring, and the other relying upon history-based traffic predictions. In both cases, we formulate global network optimization objectives as concave functions that capture the fair sharing of network capacity among competing traffic flows. The convexity of our problem formulations ensures globally optimal solutions.","Title: Network DVR: a programmable framework for application-aware trace collection\nYear: 2010\n\nAbstract: Network traces are essential for a wide range of network applications, including traffic analysis, network measurement, performance monitoring, and security analysis. Existing capture tools do not have sufficient built-in intelligence to understand these application requirements. Consequently, they are forced to collect all packet traces that might be useful at the finest granularity to meet a certain level of accuracy requirement. It is up to the network applications to process the per-flow traffic statistics and extract meaningful information. But for a number of applications, it is much more efficient to record packet sequences for flows that match some application-specific signatures, specified using for example regular expressions. A basic approach is to begin memory-copy (recording) when the first character of a regular expression is matched. However, often times, a matching eventually fails, thus consuming unnecessary memory resources during the interim. In this paper, we present a programmable application-aware triggered trace collection system called Network DVR that performs precisely the function of packet content recording based on user-specified trigger signatures. This in turn significantly reduces the number of memory copies that the system has to consume for valid trace collection, which has been shown previously as a key indicator of system performance [8]. We evaluated our Network DVR implementation on a practical application using 10 real datasets that were gathered from a large enterprise Internet gateway. In comparison to the basic approach in which the memory-copy starts immediately upon the first character match without triggered-recording, Network DVR was able to reduce the amount of memory-copies by a factor of over 500× on average across the 10 datasets and over 800× in the best case.","Title: Efficient Traffic Load-Balancing via Incremental Expansion of Routing Choices.\nYear: 2019\n\nAbstract: Routing policies play a major role in the performance of communication networks. Backpressure-based adaptive routing algorithms where traffic is load balanced along different routing paths on a per-packet basis have been studied extensively in the literature. Although backpressure-based algorithms have been shown to be networkwide throughput optimal, they typically have poor delay performance under light or moderate loads, because packets may be sent over unnecessarily long routes. Further, backpressure-based algorithms have required every node to compute differential backlogs for every per-destination queue with the corresponding per-destination queue at every adjacent node, which is expensive given the large number of possible pairwise differential backlogs between neighbor nodes. In this article, we propose new backpressure-based adaptive routing algorithms that only use shortest-path routes to destinations when they are sufficient to accommodate the given traffic load, but the proposed algorithms will incrementally expand routing choices as needed to accommodate increasing traffic loads. We show analytically by means of fluid analysis that the proposed algorithms retain networkwide throughput optimality, and we show empirically by means of simulations that our proposed algorithms provide substantial improvements in delay performance. Our evaluations further show that, in practice, our approach dramatically reduces the number of pairwise differential backlogs that have to be computed and the amount of corresponding backlog information that has to be exchanged, because routing choices are only incrementally expanded as needed.","Title: Trained Biased Number Representation for ReRAM-Based Neural Network Accelerators\nYear: 2019\n\nAbstract: Recent works have demonstrated the promise of using resistive random access memory (ReRAM) to perform neural network computations in memory. In particular, ReRAM-based crossbar structures can perform matrix-vector multiplication directly in the analog domain, but the resolutions of ReRAM cells and digital/analog converters limit the precisions of inputs and weights that can be directly supported. Although convolutional neural networks (CNNs) can be trained with low-precision weights and activations, previous quantization approaches are either not amenable to ReRAM-based crossbar implementations or have poor accuracies when applied to deep CNNs on complex datasets. In this article, we propose a new CNN training and implementation approach that implements weights using a trained biased number representation, which can achieve near full-precision model accuracy with as little as 2-bit weights and 2-bit activations on the CIFAR datasets. The proposed approach is compatible with a ReRAM-based crossbar implementation. We also propose an activation-side coalescing technique that combines the steps of batch normalization, non-linear activation, and quantization into a single stage that simply performs a clipped-rounding operation. Experiments demonstrate that our approach outperforms previous low-precision number representations for VGG-11, VGG-13, and VGG-19 models on both the CIFAR-10 and CIFAR-100 datasets.","Title: A Self-aware Resource Management Framework for Heterogeneous Multicore SoCs with Diverse QoS Targets\nYear: 2019\n\nAbstract: In modern heterogeneous MPSoCs, the management of shared memory resources is crucial in delivering end-to-end QoS. Previous frameworks have either focused on singular QoS targets or the allocation of partitionable resources among CPU applications at relatively slow timescales. However, heterogeneous MPSoCs typically require instant response from the memory system where most resources cannot be partitioned. Moreover, the health of different cores in a heterogeneous MPSoC is often measured by diverse performance objectives. In this work, we propose the Self-Aware Resource Allocation framework for heterogeneous MPSoCs. Priority-based adaptation allows cores to use different target performance and self-monitor their own intrinsic health. In response, the system allocates non-partitionable resources based on priorities. The proposed framework meets a diverse range of QoS demands from heterogeneous cores. Moreover, we present a runtime scheme to configure priority-based adaptation so that distinct sensitivities of heterogeneous QoS targets with respect to memory allocation can be accommodated. In addition, the priority of best-effort cores can also be regulated.","Title: ROAD - Routability Analysis and Diagnosis Framework Based on SAT Techniques.\nYear: 2019\n\nAbstract: Routability diagnosis has increasingly become the bottleneck in detailed routing for sub-10nm technology due to the limited tracks, high density, and complex design rules. The conventional ways to examine the routability of detailed routing are ILP- and SAT-based techniques. However, once we identify the routability, the diagnosis remains an open problem for physical designers. In this paper, we propose a novel framework, called ROAD, which diagnoses explicit reasons for routing failures. The proposed ROAD framework utilizes a diagnosis-friendly SAT formulation to represent design's layout and diagnoses the routability with SAT solving techniques. Based on the diagnosis, ROAD provides human-interpretable explanations for conflicted routing conditions. To show the practical value of our framework, we also generate comprehensive test-sets that enable exhaustive exploration of layouts based on Rent's rule. We demonstrate that ROAD successfully examines conflict causes for diverse pin layouts. Throughout extensive diagnosis, we also present several key findings for design failure. ROAD performs routability diagnosis within 2 minutes on average for 90 grids testsets, while diagnosing the exact causes of routing failures in terms of congestion and conditional design rules.","Title: Uniform Minimal First: Latency Reduction in Throughput-Optimal Oblivious Routing for Mesh-Based Networks-on-Chip\nYear: 2019\n\nAbstract: Mesh-based networks-on-chips (NoCs) are increasingly used for on-chip communications in embedded multicore processors. O1TURN is a well-known oblivious routing algorithm for mesh-based NoCs that has been shown to be worst-case throughput optimal for even network radices, but not for odd radices. More recently, another oblivious routing algorithm called U2TURN has been shown to be worst-case throughput optimal for both odd and even radices. This is accomplished by load-balancing among 2-turn paths in XYX or YXY routing, including nonminimal paths. Besides being worst-case throughput optimal, U2TURN achieves higher throughput than O1TURN under adversarial traffic. However, for random traffic, where the traffic is inherently load-balanced, O1TURN achieves lower network latency since it only considers minimal paths. In this letter, we propose a hybrid oblivious routing algorithm called uniform-minimal-first (UMF) routing. UMF works by exploiting any inherent load-balancing characteristics of the traffic pattern to reduce packet latency, but it retains the throughput optimality of U2TURN for both odd and even radices, and it achieves the performance of U2TURN under adversarial traffic. UMF is very inexpensive to implement as it just requires incrementing two small counters, but only for the head flit when a node injects a new packet (not for any pass-through traffic). These simple updates can be performed one cycle ahead of packet injection to avoid slowing down any router pipeline stage. Despite its simplicity, UMF outperforms U2TURN by 23.7% under random traffic and O1TURN by 12.6% under adversarial traffic.","Title: Learning Accurate And Interpretable Decision Rule Sets From Neural Networks\nYear: 2021\n\nAbstract: This paper proposes a new paradigm for learning a set of independent logical rules in disjunctive normal form as an interpretable model for classification. We consider the problem of learning an interpretable decision rule set as training a neural network in a specific, yet very simple two-layer architecture. Each neuron in the first layer directly maps to an interpretable if-then rule after training, and the output neuron in the second layer directly maps to a disjunction of the first-layer rules to form the decision rule set. Our representation of neurons in this first rules layer enables us to encode both the positive and the negative association of features in a decision rule. State-of-the-art neural net training approaches can be leveraged for learning highly accurate classification models. Moreover, we propose a sparsity-based regularization approach to balance between classification accuracy and the simplicity of the derived rules. Our experimental results show that our method can generate more accurate decision rule sets than other state-of-the-art rule-learning algorithms with better accuracy-simplicity trade-offs. Further, when compared with uninterpretable black-box machine learning approaches such as random forests and full-precision deep neural networks, our approach can easily find interpretable decision rule sets that have comparable predictive performance.","Title: CoRe-ECO: Concurrent Refinement of Detailed Place-and-Route for an Efficient ECO Automation\nYear: 2021\n\nAbstract: With the relentless scaling of technology nodes, physical design engineers encounter non-trivial challenges caused by rapidly increasing design complexity, particularly in the routing stage. Back-end designers must manually stitch/modify all of the design rule violations (DRVs) that remain after automatic place-and-route (P&R), during the implementation of engineering change orders (ECOs). In ...","Title: Design and System Technology Co-Optimization Sensitivity Prediction for VLSI Technology Development using Machine Learning\nYear: 2021\n\nAbstract: As technology nodes evolve, geometric pitch scaling starts to slow down. In order to retain the trend of the Moore's Law, Design Technology Co-Optimization (DTCO) and System Technology Co-Optimization (STCO) are introduced together to continue scaling beyond 5nm using pitch scaling, patterning, and novel 3D cell structures (i.e., Complementary-FET (CFET)). However, numerous DTCO and STCO iteration...","Title: Knowledge-Augmented Methods for Natural Language Processing.\nYear: 2022\n\nAbstract: Knowledge in natural language processing (NLP) has been a rising trend especially after the advent of large scale pre-trained models. NLP models with attention to knowledge can i) access unlimited amount of external information; ii) delegate the task of storing knowledge from its parameter space to knowledge sources; iii) obtain up-to-date information; iv) make prediction results more explainable via selected knowledge. In this tutorial, we will introduce the key steps in integrating knowledge into NLP, including knowledge grounding from text, knowledge representation and fusing. In addition, we will introduce recent state-of-the-art applications in fusing knowledge into language understanding, language generation and commonsense reasoning.","Title: Monolithic 3D Semiconductor Footprint Scaling Exploration Based on VFET Standard Cell Layout Methodology, Design Flow, and EDA Platform\nYear: 2022\n\nAbstract: Continued scaling in accordance with Moore's law is becoming increasingly difficult. Pitch shrinkage and standard cell height reduction via design technology co-optimization with design rules have sustained this scaling until recently. However, we observe that standard cell device scaling is becoming saturated due to yield and cost. One way to continue device footprint reduction is by expanding in the third dimension via monolithic 3D integration, using for example stacked gate-all-around (GAA) devices, complementary FETs, vertical FETs, and 3D logic. However, using these footprint scaling approaches to increase device density creates new problems. Using vertical gate-all-around FET (VFET) technologies as a specific instance of 3D device scaling, we demonstrate that the key bottleneck to footprint scaling is the pin density wall. The footprint of a block is predominantly limited by the pin density as we increase the number of active device layers. While a full-blown paradigm shift on layout methodology, design flow, and electronic design automation (EDA) platform is not available now, we describe in this article three specific baby steps that can alleviate the pin density problem and demonstrate their potential benefits for footprint scaling: (1) allocating standard cell pin sideways and using block-level routing with the local interconnect layers; (2) using the backside of the substrate for the power distribution network; and (3) using the generation of more complex standard cells. We show via several core designs that a 42.6% reduction in the core area is achievable when a combination of these operations is employed.","Title: Machine Learning Prediction for Design and System Technology Co-Optimization Sensitivity Analysis\nYear: 2022\n\nAbstract: As technology nodes continue to advance relentlessly, geometric pitch scaling starts to slow down. In order to retain the trend of Moore’s law, design technology co-optimization (DTCO) and system technology co-optimization (STCO) are introduced together to continue scaling beyond 5 nm using pitch scaling, patterning, and novel 3-D cell structures [i.e., complementary-FET (CFET)]. However, numerous DTCO and STCO iterations are needed to continue block-level area scaling with considerations of physical layout factors: 1) various standard cell (SDC) library sets (i.e., different cell heights and conventional FET); 2) design rules (DRs); 3) back end of line (BEOL) settings; and 4) power delivery network (PDN) configurations. The growing turnaround time (TAT) among SDC design, DR optimization, and block-level area evaluation becomes one of the major bottlenecks in DTCO and STCO explorations. In this work, we develop a machine learning model that combines bootstrap aggregation and gradient boosting techniques to predict the sensitivity of minimum valid block-level area of various physical layout factors. We first demonstrate that the proposed model achieves 16.3% less mean absolute error (MAE) than the previous work for testing sets. Then, we show that the proposed model successfully captures the block-level area sensitivity of new SDC library sets, new BEOL settings, and new PDN settings with 0.013, 0.004, and 0.027 MAE, respectively. Finally, compared to the previous work, the proposed approach improves the robustness of predicting new circuit designs by up to 6.76%. The proposed framework provides more than \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$100\\times $ </tex-math></inline-formula>\n speedup compared to conventional DTCO and STCO exploration flows.","Title: Spectrum Pursuit With Residual Descent for Column Subset Selection Problem: Theoretical Guarantees and Applications in Deep Learning\nYear: 2022\n\nAbstract: We propose a novel technique for dataset summarization by selecting representatives from a large, unsupervised dataset. The approach is based on the concept of self-rank, defined as the minimum number of samples needed to express all dataset samples with an accuracy proportional to the rank-K approximation. As the exact computation of self-rank requires a computationally expensive combinatorial search, we propose an efficient algorithm that jointly estimates self-rank and selects the most informative samples in a linear order of complexity w.r.t the data size. We derive a new upper bound for the approximation ratio (AR), the ratio of obtained projection error using selected samples to the best rank-K approximation error. The best previously known AR for self-representative low-rank approximation was presented in ICML 2017, which was further improved by the bound root 1 + K reported in NeurIPS 2019. Both of these bounds are obtained by brute force search, which is not practical, and these bounds depend solely on K, the number of selected samples. In contrast, we describe an adaptive AR that takes into consideration the spectral properties and spikiness measure of the original dataset, A is an element of R-NxM. In particular, our performance bound is proportional to the condition number kappa(A). Our derived AR is expressed as 1 + (kappa(A)(2) - 1)/(N - K), which approaches 1 and is optimal in two extreme spectral distribution instances. In the worst case, AR is shown not to exceed 1.25 for the proposed method. Our proposed algorithm enjoys linear complexity w.r.t. size of original dataset, which results in filling a historical gap between practical and theoretical methods in finding representatives. In addition to evaluating the proposed algorithm on a synthetic dataset, we show that it can be utilized in real-world applications such as graph node sampling for optimizing the shortest path criterion, learning a classifier with representative data, and open-set identification.","Title: LiteCON: An All-photonic Neuromorphic Accelerator for Energy-efficient Deep Learning\nYear: 2022\n\nAbstract: Deep learning is highly pervasive in today's data-intensive era. In particular, convolutional neural networks (CNNs) are being widely adopted in a variety of fields for superior accuracy. However, computing deep CNNs on traditional CPUs and GPUs brings several performance and energy pitfalls. Several novel approaches based on ASIC, FPGA, and resistive-memory devices have been recently demonstrated with promising results. Most of them target only the inference (testing) phase of deep learning. There have been very limited attempts to design a full-fledged deep learning accelerator capable of both training and inference. It is due to the highly compute- and memory-intensive nature of the training phase. In this article, we propose LiteCON, a novel analog photonics CNN accelerator. LiteCON uses silicon microdisk-based convolution, memristor-based memory, and dense-wavelength-division-multiplexing for energy-efficient and ultrafast deep learning. We evaluate LiteCON using a commercial CAD framework (IPKISS) on deep learning benchmark models including LeNet and VGG-Net. Compared to the state of the art, LiteCON improves the CNN throughput, energy efficiency, and computational efficiency by up to 32×, 37×, and 5×, respectively, with trivial accuracy degradation.","Title: JARVA: Joint Application-Aware Oblivious Routing and Static Virtual Channel Allocation\nYear: 2022\n\nAbstract: This article proposes a joint application-aware oblivious routing and static virtual channel allocation framework to enable better deadlock-free performance in on-chip interconnection networks."],"string":"[\n \"Title: BRICK: A Novel Exact Active Statistics Counter Architecture\\nYear: 2008\\n\\nAbstract: In this paper, we present an exact active statistics counter architecture called Bucketized Rank Indexed Counters (BRICK) that can efficiently store per-flow variable-width statistics counters entirely in SRAM while supporting both fast updates and lookups (e.g., 40-Gb/s line rates). BRICK exploits statistical multiplexing by randomly bundling counters into small fixed-size buckets and supports dynamic sizing of counters by employing an innovative indexing scheme called rank indexing. Experiments with Internet traces show that our solution can indeed maintain large arrays of exact active statistics counters with moderate amounts of SRAM.\",\n \"Title: Pipelined Van Emde!Boas Tree: Algorithms, Analysis, And Applications\\nYear: 2007\\n\\nAbstract: Priority queues are essential for various network processing applications, including per-flow queueing with Quality-of-Service (QoS) guarantees, management of large fast packet buffers, and management of statistics counters. In this paper, we propose a new data structure for implementing high-performance priority queues based on a pipelined version of the van Emde Boas tree. We show that we can achieve O(1) amortized time operations using our architecture, but we can achieve this algorithmic efficiency using only O(log log u) number of pipelined stages, where u is the size of the universe used to represent the priority keys.\",\n \"Title: Block-based packet buffer with deterministic packet departures\\nYear: 2010\\n\\nAbstract: Routers need to store temporarily a large number of packets in response to congestion. DRAM is typically needed to implement large packet buffers, but DRAM devices have worst-case random access latencies that are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into three categories: prefetching-based, randomization-based, and reservation-based. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. In this paper, we present an efficient reservation-based packet buffer architecture based on the concept of blocks. The proposed block-based solution achieves an order of magnitude reduction in the total SRAM size. It is scalable to growing packet storage requirements in routers while matching increasing line rates.\",\n \"Title: Communication based logic partitioning\\nYear: 1992\\n\\nAbstract: ln this paper we address the problem of partitioning, or decomposing a combinational logic specification. Most partitioning algorithms partition circuits by manipulating the implementation of the circuit, i.e., the gates, latches, etc. that realize the circuit. Our method operates on the logic speci~caiion bejore the synthesis and mapping steps have been performed. Thts g~ves us more freedom to find a good circuit decomposition and allows us to manipulate the logic as needed. The main goal oj OUT algorithm is to minimize the number oj pans needed to implement the vesulting partitions. This is accomplished by adding logic to reduce the numbeT oj pins, and by minimizing the number of pins required jor inter-pai-tttion communication by encoding the signals that flow between partitions. We have implemented our algomthrns z.sing Binary Decision Diagrams and have observed reductions oj up to 79 % in the number of pins added for the partition.\",\n \"Title: Efficient symbolic support manipulation\\nYear: 1993\\n\\nAbstract: An incompletely specified function can be given by an interval (g, h) or alternatively by a function f and a don't care set d. Depending on the assignment of don't cares, a different compatible function with a possibly support set may be derived. In this paper, efficient symbolic algorithms based on BDDs are presented for finding a compatible function with the minimum support. Efficient solution to this problem has important application in FPGA synthesis\",\n \"Title: Explicit modeling of control and data for improved NoC router estimation\\nYear: 2012\\n\\nAbstract: Networks-on-Chip (NoCs) are scalable fabrics for interconnection networks used in many-core architectures. ORION2.0 is a widely adopted NoC power and area estimation tool; however, its models for area, power and gate count can have large errors (up to 110% on average) versus actual implementation. In this work, we propose a new methodology that analyzes netlists of NoC routers that have been placed and routed by commercial tools, and then performs explicit modeling of control and data paths followed by regression analysis to create highly accurate gate count, area and power models for NoCs. When compared with actual implementations, our new models have average estimation errors of no more than 9.8% across microarchitecture and implementation parameters. We further describe modeling extensions that enable more detailed flit-level power estimation when integrated with simulation tools such as GARNET.\",\n \"Title: A System Design Methodology for Telecommunication Network Applications\\nYear: 1997\\n\\nAbstract: We describe a system design methodology, well-suited for telecom network applications. This methodology is being developed into a compiler called Matisse. The entry point for this methodology is a system specification model that is first compiled into an abstract machine. The abstract machine is implementation-independent, which permits the exploration of different embedded hardware/software realizations. The proposed methodology and tools bridge the gap between system specification and synthesis tools commercially available. This yields several advantages over the design methodology currently used in industry.\",\n \"Title: Software synthesis of process-based concurrent programs\\nYear: 1998\\n\\nAbstract: We present a Petri net theoretic approach to the software synthesis problem that can synthesize ordinary C programs from process-based concurrent specifications without the need for a run-time multithreading environment. The synthesized C programs can be readily retargeted to different processors using available optimizing C compilers. Our compiler can also generate sequential Java programs as output, which can also be readily mapped to a target processor without the need for a multithreading environment. Initial results demonstrate significant potentials for improvements over current run-time solutions.\",\n \"Title: A communicating Petri net model for the design of concurrent asynchronous modules\\nYear: 1994\\n\\nAbstract: Current asynchronous tools are focussed mainly on the design of a single interface module. In many applications, one must design interacting interface modules that potentially communicate in complex and intricate ways. When designing communicating asynchronous modules, several difficult problems arise. First, even if each individual module can be synthesized correctly, according to the environmental assumptions specified for that module, the com- position of the communicating modules may not work properly. Thus, one needs to have a way to model how the modules interact with each other, and to verify that their cooperation is consistent. In addition, means should be provided for communication and syn- chronization at a level higher than signal transitions, and for ex- ploiting the communicating nature of these modules in optimiza- tion. This paper proposes a communicating Petri net model for de- scribing communicating asynchronous modules. Each module is modeled by means of a labeled Petri net that extends the widely used Signal Transition Graph model by providing an abstract syn- chronization mechanism based on rendez-vous semantics. This en- ables the designer to specify high-level communication as well as low-level details such as signal transitions. Abstract synchroniza- tion events are expanded automatically to low-level handshake sig- nals. We have developed a new algebra for communicating Petri nets that is applicable to general Petri nets, involves no unfolding, and defines hiding as generalized net contraction. We have devel- oped methods based on this formal algebra that can be used to ma- nipulate communicating interface modules, to verify their consis- tency, and to use them as a basis for optimizations. in a concise way is needed as system interfaces are naturally expressed as separate modules, and in which the individual systems themselves are also described separately. Also, the implementation may force a separate physical implementation. Real-life designs show that asynchronous system designs are inherently distributive and involve highly interactive controllers. While work based on Hoare's CSP model have addressed some problems with communi- cating modules (2, 6), these methods are mainly based on syntax- directed translation techniques, which have not shown the same degree of automation and optimization as their STG based counter- parts. When designing communicating asynchronous interface mod- ules, a number of difficult problems arise. A major issue is correct- ness. Although current methods guarantee that each separate block is synthesized correctly, they do not guarantee the global correct- ness of the composed system. To reconcile such problems, one needs to have ways to model how the interface modules interact with each other and to verify that their cooperation is consistent. For this, we propose a high-level communicating Petri net model, called Communicating Interface Processes (CIP) for describing communicating system interfaces. Each individual interface com- ponent is modeled by means of a labeled Petri net that extends the widely used STG model by providing an abstract synchronization mechanism based on rendez-vous semantics. This enables the designer to model how the concurrent interface processes cooperate and to specify high-level communication as well as low-level details such as signal transitions. Abstract synchronization events are expanded automatically to low-level handshake signals at a later stage, which can help to avoid potential communication mis- matches that often occur with signal-level interactions. Since these ev ents are expanded to a synchronization mechanism, correctness is ensured. Accordingly, we hav e developed a new algebra on this model of abstract communication graphs to describe and formally reason about manipulations from synthesis and analysis points of view.\",\n \"Title: Design and Analysis of a Robust Pipelined Memory System\\nYear: 2010\\n\\nAbstract: Many network processing applications require wire-speed access to large data structures or a large amount of flow-level data, but the capacity of SRAMs is woefully inadequate in many cases. In this paper, we analyze a robust pipelined memory architecture that can emulate an ideal SRAM by guaranteeing with very high probability that the output sequence produced by the pipelined memory architecture is the same as the one produced by an ideal SRAM under the same sequence of memory read and write operations, except time-shifted by a fixed pipeline delay of ¿. The design is based on the interleaving of DRAM banks together with the use of a reservation table that serves in part as a data cache. In contrast to prior interleaved memory solutions, our design is robust even under adversarial memory access patterns, which we demonstrate through a rigorous worst-case theoretical analysis using a combination of convex ordering and large deviation theory.\",\n \"Title: Randomized Throughput-Optimal Oblivious Routing for Torus Networks\\nYear: 2013\\n\\nAbstract: In this paper, we study the problem of optimal oblivious routing for 1D and 2D torus networks. We introduce a new closed-form oblivious routing algorithm called W2TURN that is worst-case throughput optimal for 2D torus networks. W2TURN is based on a weighted random selection of paths that contain at most two turns. Restricting the maximum number of turns in routing paths to just two enables a simple deadlock-free implementation of W2TURN. In terms of average hop count, W2TURN outperforms the best previously known closed-form worst-case throughput optimal routing algorithm called IVAL [CHECK END OF SENTENCE]. When the network radix is odd, W2TURN achieves the minimum average hop count that can be achieved with 2-turn paths while remaining worst-case throughput optimal. When the network radix is even, W2TURN comes very close to achieving the minimum average hop count while remaining worst-case throughput optimal, within just 0.72 percent on a 12\\\\times 12 torus. We also describe another routing algorithm based on weighted random selection of paths with at most two turns called I2TURN and show that I2TURN is equivalent to IVAL. However, I2TURN eliminates the need for loop removal at runtime and provides a closed-form analytical expression for evaluating the average hop count. The latter enables us to demonstrate analytically that W2TURN strictly outperforms IVAL (and I2TURN) in average hop count. Finally, we present a new optimal weighted random routing algorithm for rings called Weighted Random Direction (WRD). WRD provides a closed-form expression for the optimal distribution of traffic along the minimal and nonminimal directions in a ring topology to achieve minimum average hop count while guaranteeing optimal worst-case throughput. Based on our evaluations, in addition to being worst-case throughput optimal, W2TURN and WRD also perform well in the average case, and outperform the best previously known worst-case throughput optimal routing algorithms with closed-form descriptions in latency and throughput over a wide range of traffic patterns.\",\n \"Title: Adaptive Frequency Counting over Bursty Data Streams\\nYear: 2007\\n\\nAbstract: We investigate the problem of frequent itemset mining over a data stream with bursty traffic. In many modern applications, data arrives at a system as a continuous stream of transactions. In many cases, the arrvial rate of transactions fluctuates wildly. Traditional stream mining algorithms, such as Lossy Counting (LC), were generally designed to handle data streams with steady data arrival rates. We show that LC suffers significant loss of accuracy when the data stream is bursty. We propose the Adaptive Frequency Counting algorithm (AFC) to handle bursty data. AFC has a feedback mechanism that dynamically adjusts the mining speed to cope with the changing data arrival rate. Through extensive experiments, we show that AFC outperforms LC under bursty traffics in terms of the accuracy of the set of freqeunt itemsets.\",\n \"Title: Application-specific Network-on-Chip architecture synthesis based on set partitions and Steiner Trees\\nYear: 2008\\n\\nAbstract: This paper considers the problem of synthesizing application-specific Network-on-Chip (NoC) architectures. We propose two heuristic algorithms called CLUSTER and DECOMPOSE that can systematically examine different set partitions of communication flows, and we propose Rectilinear-Steiner-Tree (RST) based algorithms for generating an efficient network topology for each group in the partition. Different evaluation functions in fitting with the implementation backend and the corresponding implementation technology can be incorporated into our solution framework to evaluate the implementation cost of the set partitions and RST topologies generated. In particular, we experimented with an implementation cost model based on the power consumption parameters of a 70nm process technology where leakage power is a major source of energy consumption. Experimental results on a variety of NoC benchmarks showed that our synthesis results can on average achieve a 6.92x reduction in power consumption over the best standard mesh implementation. To further gauge the effectiveness of our heuristic algorithms, we also implemented an exact algorithm that enumerates all distinct set partitions. For the benchmarks where exact results could be obtained, our CLUSTER and DECOMPOSE algorithms on average can achieve results within 1% and 2% of exact results, with execution times all under 1 second whereas the exact algorithms took as much as 4.5 hours.\",\n \"Title: A general state graph transformation framework for asynchronous synthesis\\nYear: 1994\\n\\nAbstract: No abstract available.\",\n \"Title: The taming of the shrew: mitigating low-rate TCP-targeted attack\\nYear: 2010\\n\\nAbstract: A Shrew attack, which uses a low-rate burst carefully designed to exploit TCP's retransmission timeout mechanism, can throttle the bandwidth of a TCP flow in a stealthy manner. While such an attack can significantly degrade the performance of all TCP-based protocols and services including Internet routing (e.g., BGP), no existing scheme clearly solves the problem in real network scenarios. In this paper, we propose a simple protection mechanism, called SAP (Shrew Attack Protection), for defending against a Shrew attack. Rather than attempting to track and isolate Shrew attackers, SAP identifies TCP victims by monitoring their drop rates and preferentially admits those packets from the victims with high drop rates to the output queue. This is to ensure that well-behaved TCP sessions can retain their bandwidth shares. Our simulation results indicate that under a Shrew attack, SAP can prevent TCP sessions from closing, and effectively enable TCP flows to maintain high throughput. SAP is a destination-port-based mechanism and requires only a small number of counters to find potential victims, which makes SAP readily implementable on top of existing router mechanisms.\",\n \"Title: Trace-driven optimization of networks-on-chip configurations\\nYear: 2010\\n\\nAbstract: Networks-on-chip (NoCs) are becoming increasingly important in general-purpose and application-specific multi-core designs. Although uniform router configurations are appropriate for general-purpose NoCs, router configurations for application-specific NoCs can be non-uniformly optimized to application-specific traffic characteristics. In this paper, we specifically consider the problem of virtual channel (VC) allocation in application-specific NoCs. Prior solutions to this problem have been average-rate driven. However, average-rate models are poor representations of real application traffic, and can lead to designs that are poorly matched to the application. We propose an alternate trace-driven paradigm in which configuration of NoCs is driven by application traces. We propose two simple greedy trace-driven VC allocation schemes. Compared to uniform allocation, we observe up to 51% reduction in the number of VCs under a given average packet latency constraint, or up to 74% reduction in average packet latency with same number of VCs. Our results suggest that average-rate driven methods cannot effectively select appropriate links for VC allocation because they fail to consider the impact of traffic bursts. As a case study, we compare our proposed approach with an existing average-rate driven method [9] and observe up to 35% reduction in the number of VCs for a given target latency.\",\n \"Title: Design and performance analysis of a DRAM-based statistics counter array architecture\\nYear: 2009\\n\\nAbstract: The problem of maintaining efficiently a large number (say millions) of statistics counters that need to be updated at very high speeds (e.g. 40 Gb/s) has received considerable research attention in recent years. This problem arises in a variety of router management and data streaming applications where large arrays of counters are used to track various network statistics and implement various counting sketches. It proves too costly to store such large counter arrays entirely in SRAM while DRAM is viewed as too slow for providing wirespeed updates at such high speeds. In this paper, we propose a DRAM-based counter architecture that can effectively maintain wirespeed updates to large counter arrays. The proposed approach is based on the observation that modern commodity DRAM architectures, driven by aggressive performance roadmaps for consumer applications (e.g. video games), have advanced architecture features that can be exploited to make a DRAM-based solution practical. In particular, we propose a randomized DRAM architecture that can harness the performance of modern commodity DRAM offerings by interleaving counter updates to multiple memory banks. The proposed architecture makes use of a simple randomization scheme, a small cache, and small request queues to statistically guarantee a near-perfect load-balancing of counter updates to the DRAM banks. The statistical guarantee of the proposed scheme is proven using a novel combination of convex ordering and large deviation theory. Our proposed counter scheme can support arbitrary increments and decrements at wirespeed, and it can support different number representations, including both integer and floating point number representations.\",\n \"Title: BRICK: a novel exact active statistics counter architecture\\nYear: 2011\\n\\nAbstract: In this paper, we present an exact active statistics counter architecture called Bucketized Rank Indexed Counters (BRICK) that can efficiently store per-flow variable-width statistics counters entirely in SRAM while supporting both fast updates and lookups (e.g., 40-Gb/s line rates). BRICK exploits statistical multiplexing by randomly bundling counters into small fixed-size buckets and supports dynamic sizing of counters by employing an innovative indexing scheme called rank indexing. Experiments with Internet traces show that our solution can indeed maintain large arrays of exact active statistics counters with moderate amounts of SRAM.\",\n \"Title: Per-flow Queue Scheduling with Pipelined Counting Priority Index\\nYear: 2011\\n\\nAbstract: For advanced per-flow service disciplines at high-speed network links, it is essential to maintain priority queues in sorted order. The scalable priority queue implementation requires managing a large number of queues at ever increasing line speeds. In this paper, we propose novel solutions to the management of priority queues using a previously proposed pipelined Counting Priority Index (pCPI) structure. We consider applications in which hundreds of thousands of priority queues may need to be maintained at line rate at each line card. We provide solutions to two specific problems: the mapping of packet departure times into a priority index, and the locating of the priority queue that contains the packet for a given departure time. We show that the pCPI structure can be effectively implemented for scheduling packets that are maintained in a large number of priority queues.\",\n \"Title: Efficient state assignment framework for asynchronous state graphs\\nYear: 1995\\n\\nAbstract: This paper presents a new efficient state assignment framework for synthesizing asynchronous state graphs. This framework operates purely at the state graph level and is applicable to a broad class of behaviors. In this paper we focus the framework for solving the complete state coding problem. This method has been automated and applied to a large set of asynchronous circuits. It achieves significant improvements in terms of both circuit area and computation time.\",\n \"Title: A time abstraction method for efficient verification of communicating systems\\nYear: 1994\\n\\nAbstract: An important practical approach to automatic verifi- cation of finite state concurrent systems is temporal logic model checking. However, a major barrier towards wider application of such methods is the state explosion problem that often occurs during the composition of complex communicating systems. In addition to being large, many systems have very deep state spaces as well. In this paper, we propose an abstraction method based on time abstraction which can significantly reduce both the size as well as the depth of the state space that must be explored during model check- ing. It is especially suited for applications involving systems that are loosely coupled in the sense that communication activity is rela- tively sparse, such as applications involving DSPs, which have large intervals of autonomous processing, with communication activity in between. All properties expressible with the temporal logic CTL or CTL - are strongly preserved under the proposed abstraction. In particular, we give a method that can replace a chain of states by a single state with a time label. The abstracted model is represented by means of a timed label transition system model. We give a composi- tion algorithm for composing the individually time abstracted models to form a global model that can be converted back to a conventional, but potentially much reduced, state space suitable for model checking. Furthermore, a similar approach can be followed in dealing with wait states in which a system is idling while waiting for an escape signal. For many cases, our approach is successful in alleviating the state explosion problem that often arises in composition of communicating systems.\",\n \"Title: A generalized state assignment theory for transformations on signal transition graphs\\nYear: 1994\\n\\nAbstract: In this article, we propose a global assignment theory for encoding state graph transformations. A con- straint satisfaction framework is proposed that can guarantee necessary and sufficient conditions for a state graph assignment to result in a transformed state graph that is free of critical races. Performing transformations at the state graph level has the advantage that the requirements imposed on the initial STG are very weak. Unlike previous methods, the initial STG need not be a live, safe, nor a free choice net. The only requirement is that the correspond- ing initial state graph is finite, connected, and has a consistent state assignment. Hence, a very broad range of signal transition graphs can be synthesized. The transformations achievable using the proposed framework correspond to very complex transformations on signal transition graphs. Even transformations that convert a free choice net into a correct non-free choice net and a 1-safe net into a correct 2-safe net are feasible. Addition of transitions that do not follow the Petri net firing rule is also possible. Even though our method can search a large solution space, we will show that it is possible to solve the problem in an exact way in acceptable CPU times in many practical cases.\",\n \"Title: A randomized interleaved DRAM architecture for the maintenance of exact statistics counters\\nYear: 2009\\n\\nAbstract: We extend a previously proposed randomized interleaved DRAM architecture [1] that can maintain wirespeed updates (say 40 Gb/s) to a large array (say millions) of counters. It works by interleaving updates to randomly distributed counters across multiple memory banks. Though unlikely, an adversary can conceivably overload a memory bank by triggering frequent updates to the same counter. In this work, we show this \\\"attack\\\" can be mitigated through caching pending updates, which can catch repeated updates to the same counter within a sliding time window. While this architecture of combining randomization with caching is simple and straightforward, the primary contribution of this work is to rigorously prove that it can handle with overwhelming probability all adversarial update patterns, using a combination of tail bound techniques, convex ordering theory, and queueing analysis.\",\n \"Title: Succinct priority indexing structures for the management of large priority queues\\nYear: 2009\\n\\nAbstract: Priority queues are an essential building block for implementing advanced per-flow service disciplines at high-speed network links. In this paper, we propose novel solutions to the scalable implementation of priority queues by decomposing the problem into two parts, a succinct priority index in SRAM that can efficiently maintain a real-time sorting of priorities, coupled with a DRAM-based implementation of large packet buffers. In particular, we propose three related novel succinct priority index data structures for implementing high-speed priority indexes: a Priority-Index (PI), a Counting-Priority-Index (CPI), and a Pipelined Counting-Priority-Index (Pipelined CPI). We show that all three structures can be very compactly implemented in SRAM using only Theta(U) space, where U is the size of the universe required to implement the priority keys (timestamps). We also show that our proposed priority index structures can be implemented very efficiently as well by leveraging hardware-optimized instructions that are readily available in modern 64-bit microprocessors. The operations on the PI and CPI structures take Theta(logW U) time, where W is the processor word-length (i.e., W = 64 bits). Alternatively, operations on the Pipelined CPI structure take constant time with only Theta(logW U) pipeline stages. Finally, we show the application of our proposed priority index structures for scalable management of large packet buffers at line speeds.\",\n \"Title: Destination-based adaptive routing on 2D mesh networks\\nYear: 2010\\n\\nAbstract: The choice of routing algorithm plays a vital role in the performance of on-chip interconnection networks. Adaptive routing is appealing because it offers better latency and throughput than oblivious routing, especially under non-uniform and bursty traffic. The performance of an adaptive routing algorithm is determined by its ability to accurately estimate congestion in the network. In this regard, maintaining global congestion information using a separate monitoring network offers better congestion visibility into distant parts of the network than solutions relying only on local congestion state. However, the main challenge in designing such routing schemes is to keep the logic and bandwidth overhead as low as possible to fit into the tight power, area and delay budgets of on-chip routers. In this paper, we propose a minimal destination-based adaptive routing strategy (DAR) where every node estimates the delay to every other node in the network, and routing decisions are based on these per-destination delay estimates. DAR outperforms Regional Congestion Awareness (RCA) [7], the best previously known adaptive routing algorithm that uses non-local congestion knowledge. This is because the per-destination delay estimates in DAR are more accurate and not corrupted by congestion on links outside the admissible routing paths to the destination. We show that DAR outperforms minimal adaptive routing by up to 65% and RCA by up to 41% in terms of latency on SPLASH-2 benchmarks. It also outperforms these algorithms in latency and throughput under synthetic traffic patterns on both 8x8 and 16x16 mesh topologies.\",\n \"Title: Performance-driven synthesis of asynchronous controllers\\nYear: 1994\\n\\nAbstract: We examine the implications of a new hazard-free combinational logic synthesis method, which generates multiplexor trees from binary decision diagrams (BDDs)—representations of logic functions factored recursively with respect to input variables—on extended burst-mode asynchronous synthesis. First, the use of the BDD-based synthesis reduces the constraints on state minimization and assignment, which reduces the number of additional state variables required in many cases. Second, in cases where conditional signals are sampled, it eliminates the need for state variable changes preceding output changes, which reduces overall input to output latency. Third, selection variables can easily be ordered to minimize the latency on a user-specified path, which is important for optimizing the performance of systems that use asynchronous components. We present extensive evaluations showing that, with only minimal optimization, the BBD-based synthesis gives comparable results in area with our previous exact two-level synthesis method. We also give a detailed example of the specified path optimization.\",\n \"Title: Hardware compilation for FPGA-based configurable computing machines\\nYear: 1999\\n\\nAbstract: Configurable computing machines are an emerging class of hybrid architectures where a field programmable gate array (FPGA) component is tightly coupled to a general-purpose microprocessor core. In these architectures, the FPGA component complements the general-purpose microprocessor by enabling a developer to construct application-specific gate-level structures on-demand while retaining the flexibility and rapid reconfigurability of a fully programmable solution. High computational performance can be achieved on the FPGA component by creating custom data paths, operators, and interconnection pathways that are dedicated to a given problem, thus enabling similar structural optimization benefits as ASICs. In this paper, we present a new programming environment for the development of applications on this new class of configurable computing machines. This environment enables developers to develop hybrid hardware/software applications in a common integrated development framework. In particular, the focus of this paper is on the hardware compilation part of the problem starting from a software-like algorithmic process-based specification. Traditionally, there has been a strong separation between software running on general-purpose programmable processors and dedicated hardware. Microprocessors can perform many different functions by providing a general mechanism to execute software. They can be programmed to perform different tasks, ranging from the execution of a word processor program to the processing of an audio stream. However, versatility comes at a price: applications implemented in software are usually much slower than their hardware counterparts. In contrast, application-specific hardware circuits provide precisely the functions needed for a specific task. Thus, they can be carefully tuned to the application, resulting in solutions that are often smaller, cheaper, faster, and more power efficient. The advent of field programmable gate arrays (FPGAs) offers an intriguing alternative. Like a general-purpose microprocessor, FPGAs can be dynamically reconfigured repeatedly to perform many different functions. However, like application-specific hardware, FPGAs can implement specific hardware structures that are tuned to the application. FPGAs consist of large arrays of reconfigurable logic blocks that can be reprogrammed to implement a specific gate-level customization. Thus, FPGAs can serve as a powerful adaptive computing engine. Indeed, a number of impressive results have been documented using reconfigurable logic for a number of applications, including RSA encryption [22], DNA sequencing [14], multi-standard video compression [22], automatic target recognition [21], and high energy physics [15], amongst others. Several recent advances have made the case for adaptive computing even more compelling. The densities and performance of FPGAs have increased by several orders of magnitude compared to earlier devices. Currently, FPGA devices with over 1M equivalent gates capacity running at 200MHz clock speeds are emerging. The dynamic reconfigurable times have also dramatically decreased despite the substantial increase in logic capacity. A new generation of devices is emerging that can be dynamically reconfigured at a rate of 250M gates/sec.\",\n \"Title: Per-Flow Queue Management with Succinct Priority Indexing Structures for High Speed Packet Scheduling\\nYear: 2013\\n\\nAbstract: Priority queues are essential building blocks for implementing advanced per-flow service disciplines and hierarchical quality-of-service at high-speed network links. Scalable priority queue implementation requires solutions to two fundamental problems. The first is to sort queue elements in real time at ever increasing line speeds (e.g., at OC-768 rates). The second is to store a huge number of packets (e.g., millions of packets). In this paper, we propose novel solutions by decomposing the problem into two parts, a succinct priority index (PI) in SRAM that can efficiently maintain a real-time sorting of priorities, coupled with a DRAM-based implementation of large packet buffers. In particular, we propose three related novel succinct PI data structures for implementing high-speed PIs: a PI, a counting priority index (CPI), and a pipelined counting priority index (pCPI). We show that all three structures can be very compactly implemented in SRAM using only $(\\\\Theta (U))$ space, where $(U)$ is the size of the universe required to implement the priority keys (time stamps). We also show that our proposed PI structures can be implemented very efficiently as well by leveraging hardware-optimized instructions that are readily available in modern 64-bit processors. The operations on the PI and CPI structures take $(\\\\Theta (\\\\log_W U))$ time complexity, where $(W)$ is the processor word length (i.e., $(W = 64)$). Alternatively, operations on the pCPI structure take amortized constant time with only $(\\\\Theta (\\\\log_W U))$ pipeline stages (e.g., only four pipeline stages for $(U = 16)$ million). Finally, we show the application of our proposed PI structures for the scalable management of large packet buffers at line speeds. The pCPI structure can be implemented efficiently in high-performance network processing applications such as advanced per-flow scheduling with quality-of-service guarantee.\",\n \"Title: Design of heterogeneous ICs for mobile and personal communication systems\\nYear: 1994\\n\\nAbstract: Mobile and personal communication systems form key market areas for the electronics industry of the nineties. Stringent requirements in terms of flexibility, performance and power dissipation, are driving the development of integrated circuits into the direction of heterogeneous single-chip solutions. New IC architectures are emerging which contain the core of a powerful programmable processor, complemented with dedicated hardware, memory and interface structures. In this tutorial we will discuss the real-life design of a heterogeneous IC for an industrial telecom application: a reconfigurable mobile terminal for satellite communication. Based on this practical design experience, we will subsequently discuss a methodology for the design of heterogeneous ICs. Design steps that will be addressed include: system specification and refinement, data path and communication synthesis, and code generation for embedded processor cores.\",\n \"Title: Weighted Random Routing on Torus Networks\\nYear: 2009\\n\\nAbstract: In this paper, we introduce a new closed-form oblivious routing algorithm called W2TURN that is worst-case throughput optimal for 2D-torus networks. W2TURN is based on a weighted random selection of paths that contain at most two turns. In terms of average hop count, W2TURN outperforms the best previously known closed-form worst-case throughput optimal routing algorithm called IVAL. In addition, we present a new optimal weighted random routing algorithm for rings called WRD.\",\n \"Title: On The Efficient Implementation Of Pipelined Heaps For Network Processing\\nYear: 2006\\n\\nAbstract: Priority queues are often used in many network processing applications. Applications include sophisticated per-flow scheduling for providing advanced Quality-of-Service (QoS) guarantees, fast packet buffer memory management, and exact maintanence of statistics counters for real-time network measurements. In all these applications, the priority queues used must operate at very high-speeds, e.g. at 40 Gbps rates and beyond. One widely used data structure for implementing priority queues is the heap data structure. However, the logarithmic time complexity of heap operations is often too slow for increasingly fast line rates. To achieve constant time complexity, the pipelined heap structure has been proposed. In this paper, we describe new architecture techniques for the efficient implementation of pipelined heaps. In particular, we focus on aggressive memory management and pipelining techniques.\",\n \"Title: Synthesis of hazard-free multilevel logic under multiple-input changes from binary decision diagrams\\nYear: 1994\\n\\nAbstract: We describe a new method for directly synthesizing a hazard-free multilevel logic implementation from a given logic specification. The method is based on free/ordered Binary Decision Diagrams (BDD's), and is naturally applicable to multiple-output logic functions. Given an incompletely-specified (multiple-output) Boolean function, the method produces a multilevel logic network that is hazard-free for a specified set of multiple-input changes. We assume an arbitrary (unbounded) gate and wire delay model under a pure delay (PD) assumption, we permit multiple-input changes, and we consider both static and dynamic hazards under the fundamental-mode assumption. Our framework is thus general and powerful. While it is not always possible to generate hazard-free implementations using our technique, we show that in some cases hazard-free multilevel implementations can be generated when hazard-free two-level representations cannot be found. This problem is generally regarded as a difficult problem and it has important applications in the field of asynchronous design. The method has been automated and applied to a number of examples\",\n \"Title: Stream execution on wide-issue clustered VLIW architectures\\nYear: 2007\\n\\nAbstract: This paper investigates the mapping of stream programs to wide-issue clustered VLIW processors so that designers can leverage their existing investments in VLIW-based platforms to harness the advantages of stream programming.\",\n \"Title: Efficient verification using generalized partial order analysis\\nYear: 1998\\n\\nAbstract: This paper presents a new formal method for the efficient verification of concurrent systems that are modeled using a safe Petri net representation. Our method generalizes upon partial-order methods to explore concurrently enabled conflicting paths simultaneously. We show that our method can achieve an exponential reduction in algorithmic complexity without resorting to an implicit enumeration approach.\",\n \"Title: LEISURE: A Framework for Load-Balanced Network-Wide Traffic Measurement\\nYear: 2011\\n\\nAbstract: Network-wide traffic measurement is of interest to network operators to uncover global network behavior for the management tasks of traffic accounting, debugging or troubleshooting, security, and traffic engineering. Increasingly, sophisticated network measurement tasks such as anomaly detection and security forensic analysis are requiring in-depth fine-grained flow-level measurements. However, performing in-depth per-flow measurements (e.g., detailed payload analysis) is often an expensive process. Given the fast-changing Internet traffic landscape and large traffic volume, a single monitor is not capable of accomplishing the measurement tasks for all applications of interest due to its resource constraint. Moreover, uncovering global network behavior requires network-wide traffic measurements at multiple monitors across the network since traffic measured at any single monitor only provides a partial view and may not be sufficient or accurate. These factors call for coordinated measurements among multiple distributed monitors. In this paper, we present a centralized optimization framework, LEISURE (Load-EqualIzed measurement), for load-balancing network measurement workloads across distributed monitors. Specifically, we consider various load-balancing problems under different objectives and study their extensions to support different deployment scenarios. We evaluate LEISURE via detailed simulations on Abilene and GEANT network traces to show that LEISURE can achieve much better load-balanced performance (e.g., 4.75X smaller peak workload and 70X smaller variance in workloads) across all coordinated monitors in comparison to naive solution (uniform assignment) to accomplish network-wide traffic measurement tasks.\",\n \"Title: Frame-aggregated concurrent matching switch\\nYear: 2007\\n\\nAbstract: Network operators need high-capacity router architectures that can offer scalability, provide throughput and performance guarantees, and maintain packet ordering. However, previous router architectures based on centralized crossbar-based architectures cannot scale to fast line rates and high port counts. Recently, a new scalable router architecture called the Concurrent Matching Switch (CMS)[5]was introduced that offers scalability by utilizing a fully distributed architecture based on two identical stages of fixed configuration meshes. It has been shown that fixed configuration meshes can be scaled to very fast line rates and highport counts via optical implementations.It has also been shown that the CMS architecture can achieve 100% through-put and packet ordering with only sequential hardware and O (1) amortized time complexity operations at each linecard. However, no delay performance guarantees have been shown for CMS. In this paper, we demonstrate a general delay performance guarantee for CMS.Based on this guarantee, we propose a novel frame-based CMS architecture that can achieve a performance guarantee of O (N log N)average packet delay, where N is the number of switch ports, while retaining scalability,throughput guarantees, packet ordering, and O (1) time complexity. This architecture improves upon the best previously-known average delay bound of O (N 2)given these switch properties. We further introduce several alternative frame-based CMS architectures.\",\n \"Title: Robust Pipelined Memory System with Worst Case Performance Guarantee for Network Processing\\nYear: 2012\\n\\nAbstract: Many network processing applications require wirespeed access to large data structures or a large amount of packet and flow-level data. Therefore, it is essential for the memory system of a router to be able to support both read and write accesses to such data at link speeds. As link speeds continue to increase, router designers are constantly grappling with the unfortunate trade-offs between the speed and cost of SRAM and DRAM. The capacity of SRAMs is woefully inadequate in many cases and it proves too costly to store large data structures entirely in SRAM, while DRAM is viewed as too slow for providing wirespeed updates at such high speed. In this paper, we analyze a robust pipelined memory architecture that can emulate an ideal SRAM by guaranteeing with very high probability that the output sequence produced by the pipelined memory architecture is the same as the one produced by an ideal SRAM under the same sequence of memory read and write operations, except time shifted by a fixed pipeline delay of Delta. Given a fixed pipeline delay abstraction, no interrupt mechanism is required to indicate when read data are ready or a write operation has completed, which greatly simplifies the use of the proposed solution. The design is based on the interleaving of DRAM banks together with the use of a reservation table that serves in part as a data cache. In contrast to prior interleaved memory solutions, our design is robust under all memory access patterns, including adversarial ones, which we demonstrate through a rigorous worst case theoretical analysis using a combination of convex ordering and large deviation theory.\",\n \"Title: Hierarchical optimization of asynchronous circuits\\nYear: 1995\\n\\nAbstract: Many asynchronous designs are naturally specified and implemented hierarchically as an interconnection of separate asyn- chronous modules that operate concurrently and communicate with each other. This paper is concerned with the problem of synthesizing such hierarchically defined systems. When the individual components are synthesized and implemented separately, it is desirable to take into account the degrees of freedom that arise from the interactions with the other components and from the specification. Specifically, we consider how one can find the set of implementations that can be \\\"correctly sub- stituted\\\" for a component in the system while preserving the behavior of the total system. The notion of correct substitution is formally de- fined for a hierarchical network of possibly non-deterministic modules and a new solution framework based on trace theory is presented to compute and represent this complete set of correct substitutions. We show that the complete set can be captured by a single trace structure using the notion of a \\\"maximal trace structure\\\". We indicate how asyn- chronous synthesis methods may be applied to explore the solution space e.g. to generate a delay-insensitive implementation. II NTRODUCTION The role of asynchronous design is gaining importance due to increasing difficulties with problems like clock skew and power dissipation. In many design scenarios, the design is most natu- rally described and implemented hierarchically as a network of separate asynchronous modules that operate concurrently and communicate with each other. Hierarchical representations are especially important when the design is compiled from a high- level language. Also, implementation constraints may force their physical implementations to be separated. Indeed, real-life de- signs show that many asynchronous applications are inherently distributive and highly interactive, thus requiring methods to handle them. When optimizing each individual component sep- arately, it is desirable to take into account the degrees of freedom that arise from the interactions with the other components and from the specification. This is analogous to the problem of op- timizing hierarchically combinational and synchronous circuits, which has been studied extensively. For the design of asynchronous control circuits, the ex- isting literature describes a number of automated algorith- mic approaches based on Petri net and state machine models (2, 4, 10, 11, 15, 20, 21, 22, 23). These works have focussed mainly on the synthesis and optimization of individual asynchronous modules without considering the optimization freedom avail- able in optimizing concurrent behavior. Methods based on mod- els of communicating processes have also been extensively stud- ied in the literature (1, 3, 13, 18). These methods are mainly based on syntax-directed translation techniques. Though these meth- ods can effectively model concurrent behavior, they also have\",\n \"Title: Sizing and verification of communication buffers for communicating processes\\nYear: 1993\\n\\nAbstract: No abstract available.\",\n \"Title: A system design methodology for software/hardware co-development of telecommunication network applications\\nYear: 1996\\n\\nAbstract: In this paper, we describe a system design methodology for the concurrent development of hybrid software/hardware systems for telecom network applications. This methodology is based on the results of an investigation and evaluation of an actual industrial system design application for ATM-based broadband networks. The aim of this methodology is to provide an integrated design flow from system specification to implementation\",\n \"Title: Custom networks-on-chip architectures with multicast routing\\nYear: 2009\\n\\nAbstract: In this paper, we consider the problem of synthesizing custom networks-on-chip (NoC) architectures that are optimized for a given application. We consider both unicast and multicast traffic flows in the input specification. Multicast traffic flows are used in a variety of applications, and their direct support with only replication of packets at optimal bifurcation points rather than full end-to-end replication can significantly reduce network contention and resource requirements. Our problem formulation is based on the decomposition of the problem into the inter-related steps of finding good flow partitions, deriving a good physical network topology for each group in the partition, and providing an optimized network implementation for the derived topologies. Our solutions may be comprised of multiple custom networks, each interconnecting a subset of communicating modules. We propose several algorithms that can systematically examine different flow partitions, and we propose Rectilinear-Steiner-Tree (RST)-based algorithms for generating efficient network topologies. Our design flow integrates floorplanning, and our solutions consider deadlock-free routing. Experimental results on a variety of NoC benchmarks showed that our synthesis results can on average achieve a 4.82 times reduction in power consumption over different mesh implementations on unicast benchmarks and a 1.92 times reduction in power consumption on multicast benchmarks. Significant improvements in performance were also achieved, with an average of 2.92 times reduction in hop count on unicast benchmarks and 1.82 times reduction in hop count on multicast benchmarks. To further gauge the effectiveness of our heuristic algorithms, we also implemented an exact algorithm that enumerates all distinct set partitions. For the benchmarks where exact results could be obtained, our algorithms on average can achieve results within 3 % of exact results, but with much shorter execution times.\",\n \"Title: A New Worst-Case Throughput Bound for Oblivious Routing in Odd Radix Mesh Network\\nYear: 2013\\n\\nAbstract: 1/2 network capacity is often believed to be the limit of worst-case throughput for mesh networks. However, this letter provides a new worst-case throughput bound, which is higher than 1/2 network capacity, for odd radix two-dimensional mesh networks. In addition, we propose a routing algorithm called U2TURN that can achieve this worst-case throughput bound. U2TURN considers all routing paths with at most 2 turns and distributes the traffic loads uniformly in both X and Y dimensions. Theoretical analysis and simulation results show that U2TURN outperforms existing routing algorithms in worst-case throughput. Moreover, U2TURN achieves good average-throughput at the expense of approximately 1.5x minimal average hop count.\",\n \"Title: A block-based reservation architecture for the implementation of large packet buffers\\nYear: 2009\\n\\nAbstract: DRAM is typically needed to implement large packet buffers, but DRAM devices have worst-case random access latencies that are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into three categories: prefetching-based [1], randomization-based [2], and reservation-based [3]. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. Each class of architectures has its own benefits. For router architectures where the departure times of packets can be deterministically calculated before the packets are inserted into the packet buffer, the reservation-based approach has the nice property that in-time packet retrievals can be guaranteed. Reservation-based architectures work by constructive placement of packets and scheduling of memory operations based on the departure times of packets.\",\n \"Title: Randomized Partially-Minimal Routing on Three-Dimensional Mesh Networks\\nYear: 2008\\n\\nAbstract: This letter presents a new oblivious routing algorithm for 3D mesh networks called Randomized Partially- Minimal (RPM) routing that provably achieves optimal worstcase throughput for 3D meshes when the network radix k is even and within a factor of 1/k2 of optimal when k is odd. Although this optimality result has been achieved with the minimal routing algorithm O1TURN [9] for the 2D case, the worst-case throughput of O1TURN degrades tremendously in higher dimensions. Other existing routing algorithms suffer from either poor worst-case throughput (DOR [10], ROMM [8]) or poor latency (VAL [14]). RPM on the other hand achieves near optimal worst-case and good average-case throughput as well as good latency performance.\",\n \"Title: Design of application-specific 3D Networks-on-Chip architectures.\\nYear: 2008\\n\\nAbstract: The increasing viability of three dimensional (3D) silicon integration technology has opened new opportunities for chip design innovations, including the prospect of extending emerging Systems-on-Chip (SoC) design paradigms based on Networks-on-Chip (NoC) interconnection architectures to 3D chip designs. In this paper, we consider the problem of designing application-specific 3D-NoC architectures that are optimized for a given application. We present novel 3D-NoC synthesis algorithms that make use of accurate power and delay models for 3D wiring with through-silicon vias. In particular, we present a very efficient 3D-NoC synthesis algorithm called Ripup-Reroute-and-Router-Merging (RRRM), that is based on a rip-up and reroute formulation for routing flows and a router merging procedure for network optimization. Experimental results on 3D-NoC design cases show that our synthesis results can on average achieve a 74% reduction in power consumption and a 17% reduction in hop count over regular 3D mesh implementations and a 52% reduction in power consumption and a 17% reduction in hop count over optimized 3D mesh implementations.\",\n \"Title: A strategy for real-time kernel support in application-specific HW/SW embedded architectures\\nYear: 1996\\n\\nAbstract: Heterogeneous embedded multiprocessor architectures are becom- ing more prominent as a key design solution to today's microelec- tronics design problems. These application-specific architectures in- tegrate multiple software programmable processors and dedicated hardwarecomponents together on to a single cost-efficient IC. In con- trast to general-purpose computer systems, embedded systems are designed and optimized to provide specific functionality, using pos- sibly a combination of different classes of processors (e.g. DSPs, mi- crocontrollers) from different vendors. While these customized het- erogeneous multiprocessor architectures offer designers new possi- bilities to tradeoff programmability, processing performance, power dissipation, and design turnaround time, there is currently a lack of tools to support the programming of these architectures. In this pa- per, we consider the problem of providing real-time kernel support for managing the concurrent software tasks that are distributed over a set of processorsin an application-specific multiprocessorarchitec- ture. This is complementary to current research activities that aim to provide efficient retargetable code generation (8, 11, 10) for a broad range of embedded processors.\",\n \"Title: Destination-based congestion awareness for adaptive routing in 2D mesh networks\\nYear: 2013\\n\\nAbstract: The choice of routing algorithm plays a vital role in the performance of on-chip interconnection networks. Adaptive routing is appealing because it offers better latency and throughput than oblivious routing, especially under nonuniform and bursty traffic. The performance of an adaptive routing algorithm is determined by its ability to accurately estimate congestion in the network. In this regard, maintaining global congestion state using a separate monitoring network offers better congestion visibility into distant parts of the network compared to solutions relying only on local congestion. However, the main challenge in designing such routing schemes is to keep the logic and bandwidth overhead as low as possible to fit into the tight power, area, and delay budgets of on-chip routers. In this article, we propose a minimal destination-based adaptive routing strategy (DAR), where every node estimates the delay to every other node in the network, and routing decisions are based on these per-destination delay estimates. DAR outperforms Regional Congestion Awareness (RCA), the best previously known adaptive routing algorithm that uses nonlocal congestion state. The performance improvement is brought about by maintaining fine-grained per-destination delay estimates in DAR that are more accurate than regional congestion metrics measured in RCA. The increased accuracy is a consequence of the fact that the per-destination delay estimates are not corrupted by congestion on links outside the admissible routing paths to the destination. A scalable version of DAR, referred to as SDAR, is also proposed for minimizing the overheads associated with DAR in large network topologies. We show that DAR outperforms local adaptive routing by up to 79% and RCA by up to 58% in terms of latency on SPLASH-2 benchmarks. DAR and SDAR also outperform existing adaptive and oblivious routing algorithms in latency and throughput under synthetic traffic patterns on 8×8 and 16times;16 mesh topologies, respectively.\",\n \"Title: An Oblivious Routing Algorithm for 3D Mesh Networks to Achieve a New Worst-Case Throughput Bound\\nYear: 2012\\n\\nAbstract: 1/2 network capacity is often believed to be the limit of worst-case throughput for three-dimension (3D) mesh networks. However, this paper provides a new worst-case throughput bound, which is higher than 1/2 network capacity, for odd radix 3D mesh networks. In addition, we propose a routing algorithm called uniform solo-minimal (USM) routing that can achieve this new worst-case throughput bound in odd radix mesh networks. For the even radix case, we prove that USM achieves the optimal worst-case throughput, namely, half of network capacity. USM considers all routing paths with at most one dimensional minimal-distance routing and distributes the traffic loads uniformly to other two left dimensions. Theoretical analysis and simulation results show that USM outperforms existing routing algorithms in worst-case throughput. Moreover, USM achieves good average-throughput and performs very well under different traffic matrices at the expense of $({5}/{3})\\\\\\\\times$ minimal average hop count.\",\n \"Title: Enhanced metamodeling techniques for high-dimensional IC design estimation problems\\nYear: 2013\\n\\nAbstract: Accurate estimators of key design metrics (power, area, delay, etc.) are increasingly required to achieve IC cost reductions in system-level through physical layout optimizations. At the same time, identifying physical or analytical models of design metrics has become very challenging due to interactions among many parameters that span technology, architecture and implementation. Metamodeling techniques can simplify this problem by deriving surrogate models from samples of actual implementation data. However, the use of metamodeling techniques in IC design estimation is still in its infancy, and practitioners need more systematic understanding. In this work, we study the accuracy of metamodeling techniques across several axes: (1) low- and high-dimensional estimation problems, (2) sampling strategies, (3) sample sizes, and (4) accuracy metrics. To help obtain more general conclusions, we study these axes for three very distinct chip design estimation problems: (1) area and power of networks-on-chip routers, (2) delay and output slew of standard cells under power delivery network noise, and (3) wirelength and buffer area of clock trees. Our results show that (1) adaptive sampling can effectively reduce the sample size required to derive surrogate models by up to 64% (or, increase estimation accuracy by up to 77%) compared with Latin hypercube sampling; (2) for low-dimensional problems, Gaussian process-based models can be 1.5x more accurate than tree-based models, whereas for high-dimensional problems, tree-based models can be up to 6x more accurate than Gaussian process-based models; and (3) a variant of weighted surrogate modeling [7], which we call hybrid surrogate modeling, can improve estimation accuracy by up to 3x. Finally, to aid architects, design teams, and CAD developers in selection of the appropriate metamodeling techniques, we propose guidelines based on the insights gained from our studies.\",\n \"Title: Guest Editors' Introduction: Special Issue on Quality-of-Service.\\nYear: 2013\\n\\nAbstract: The papers in this special issue focus on quality of service in the network and services management sectors.\",\n \"Title: Compiling concurrent programs for embedded sequential execution\\nYear: 2007\\n\\nAbstract: Embedded applications are often more naturally modeled as a set of concurrent tasks, but yet they are often implemented using a single embedded processor. Traditionally, run-time operating systems have been used to simulate concurrency by timesharing the underlying processor and to facilitate inter-process communication amongst the concurrent tasks. However, this run-time approach to multi-tasking and inter-process communication can often introduce significant overhead to execution times and memory requirements, prohibitive in many cases for embedded applications where processor and memory resources are scarce. In this paper, we present compilation techniques that can statically resolve concurrency at compile-time so that the resulting code produced can be sequentially executed on an embedded processor without the need for a run-time scheduler. Our techniques are based on a novel Petri net theoretic framework. In particular, we show how a concurrent program specification can be transformed into an intermediate Petri net representation. We then show how the intermediate Petri net may be statically scheduled to produce a sequential state machine model that can be sequentially executed directly on an embedded processor without a run-time operating system. In practice, this technique produces efficient results. However, theoretically, it is possible for the resulting state machine to become very large, resulting in code explosion. To circumvent this limitation, we describe a compositional approach that can scale well to large applications and is immune to code explosion.\",\n \"Title: DRAM-Based Statistics Counter Array Architecture With Performance Guarantee\\nYear: 2012\\n\\nAbstract: The problem of efficiently maintaining a large number (say millions) of statistics counters that need to be updated at very high speeds (e.g., 40 Gb/s) has received considerable research attention in recent years. This problem arises in a variety of router management and data streaming applications where large arrays of counters are used to track various network statistics and implement various counting sketches. It proves too costly to store such large counter arrays entirely in SRAM, while DRAM is viewed as too slow for providing wirespeed updates at such high line rates. In particular, we propose a DRAM-based counter architecture that can effectively maintain wirespeed updates to large counter arrays. The proposed approach is based on the observation that modern commodity DRAM architectures, driven by aggressive performance roadmaps for consumer applications, such as video games, have advanced architecture features that can be exploited to make a DRAM-based solution practical. In particular, we propose a randomized DRAM architecture that can harness the performance of modern commodity DRAM offerings by interleaving counter updates to multiple memory banks. The proposed architecture makes use of a simple randomization scheme, a small cache, and small request queues to statistically guarantee a near-perfect load-balancing of counter updates to the DRAM banks. The statistical guarantee of the proposed randomized scheme is proven using a novel combination of convex ordering and large deviation theory. Our proposed counter scheme can support arbitrary increments and decrements at wirespeed, and they can support different number representations, including both integer and floating point number representations.\",\n \"Title: Weighted random oblivious routing on torus networks\\nYear: 2009\\n\\nAbstract: Torus, mesh, and flattened butterfly networks have all been considered as candidate architectures for on-chip interconnection networks. In this paper, we study the problem of optimal oblivious routing for one of these architecture classes, namely, the torus network. We introduce a new closed-form oblivious routing algorithm called W2TURN that is worst-case throughput optimal for 2D-torus networks. W2TURN is based on a weighted random selection of paths that contain at most two turns. Restricting the maximum number of turns in routing paths to just two results in a simple deadlock-free implementation of W2TURN. In terms of average hop count, W2TURN outperforms the best previously known closed-form worst-case throughput optimal routing algorithm called IVAL [14]. We also provide another routing algorithm based on the weighted random selection of paths with at most two turns called I2TURN and show that it is equivalent to IVAL. However, I2TURN eliminates the need for loop removal at runtime and provides a closed-form analytical expression for evaluating the average hop count. The latter enables us to demonstrate analytically that W2TURN strictly outperforms IVAL (and I2TURN) in average hop count. Finally, we present a new optimal weighted random routing algorithm for rings called WRD (Weighted Random Direction). WRD provides a closed form expression for the the optimal distribution of traffic along the minimal and non-minimal directions in a ring topology to achieve minimum average hop count under maximum worst-case throughput.\",\n \"Title: Stream Execution on Embedded Wide-Issue Clustered VLIW Architectures\\nYear: 2008\\n\\nAbstract: Very long instruction word- (VLIW-) based processors have become widely adopted as a basic building block in modern System-on-Chip designs. Advances in clustered VLIW architectures have extended the scalability of the VLIW architecture paradigm to a large number of functional units and very-wide-issue widths. A central challenge with wide-issue clustered VLIW architecture is the availability of programming and automated compiler methods that can fully utilize the available computational resources. Existing compilation approaches for clustered-VLIW architectures are based on extensions of previously developed scheduling algorithms that primarily focus on the maximization of instruction-level parallelism (ILP). However, many applications do not have sufficient ILP to fully utilize a large number of functional units. On the other hand, many applications in digital communications and multimedia processing exhibit enormous amounts of data-level parallelism (DLP). For these applications, the streaming programming paradigm has been developed to explicitly expose coarse-grained data-level parallelism as well as the locality of communication between coarse-grained computation kernels. In this paper, we investigate the mapping of stream programs to wide-issue clustered VLIW processors. Our work enables designers to leverage their existing investments in VLIW-based architecture platforms to harness the advantages of the stream programming paradigm.\",\n \"Title: A High-Throughput Distributed Shared-Buffer NoC Router\\nYear: 2009\\n\\nAbstract: Microarchitectural configurations of buffers in routers have a significant impact on the overall performance of an on-chip network (NoC). This buffering can be at the inputs or the outputs of a router, corresponding to an input-buffered router (IBR) or an output-buffered router (OBR). OBRs are attractive because they have higher throughput and lower queuing delays under high loads than IBRs. However, a direct implementation of OBRs requires a router speedup equal to the number of ports, making such a design prohibitive given the aggressive clocking and power budgets of most NoC applications. In this letter, we propose a new router design that aims to emulate an OBR practically based on a distributed shared-buffer (DSB) router architecture. We introduce innovations to address the unique constraints of NoCs, including efficient pipelining and novel flow control. Our DSB design can achieve significantly higher bandwidth at saturation, with an improvement of up to 20% when compared to a state-of-the-art pipelined IBR with the same amount of buffering, and our proposed microarchitecture can achieve up to 94% of the ideal saturation throughput.\",\n \"Title: Measurement-Aware Monitor Placement and Routing: A Joint Optimization Approach for Network-Wide Measurements.\\nYear: 2012\\n\\nAbstract: Network-wide traffic measurement is important for various network management tasks, ranging from traffic accounting, traffic engineering, network troubleshooting to security. Previous research in this area has focused on either deriving better monitor placement strategies for fixed routing, or strategically routing traffic sub-populations over existing deployed monitors to maximize the measurement...\",\n \"Title: Proactive surge protection: a defense mechanism for bandwidth-based attacks\\nYear: 2009\\n\\nAbstract: Large-scale bandwidth-based distributed denial-of-service (DDoS) attacks can quickly knock out substantial parts of a network before reactive defenses can respond. Even traffic flows that are not under direct attack can suffer significant collateral damage if these flows pass through links that are common to attack routes. Given the existence today of large botnets with more than a hundred thousand bots, the potential for a large-scale coordinated attack exists, especially given the prevalence of high-speed Internet access. This paper presents a Proactive Surge Protection (PSP) mechanism that aims to provide a broad first line of defense against DDoS attacks. The approach aims to minimize collateral damage by providing bandwidth isolation between traffic flows. This isolation is achieved through a combination of traffic measurements, bandwidth allocation of network resources, metering and tagging of packets at the network perimeter, and preferential dropping of packets inside the network. The proposed solution is readily deployable using existing router mechanisms and does not rely on any unauthenticated packet header information. Thus the approach is resilient to evading attack schemes that launch many seemingly legitimate TCP connections with spoofed IP addresses and port numbers. Finally, our extensive evaluation results across two large commercial backbone networks, using both distributed and targeted attack scenarios, show that up to 95.5% of the network could suffer collateral damage without protection, but our solution was able to significantly reduce the amount of collateral damage by up to 97.58% in terms of the number of packets dropped and 90.36% in terms of the number of flows with packet loss. Furthermore, we show that PSP can maintain low packet loss rates even when the intensity of attacks is increased significantly.\",\n \"Title: Design of a High-Throughput Distributed Shared-Buffer NoC Router\\nYear: 2010\\n\\nAbstract: Router microarchitecture plays a central role in the performance of an on-chip network (NoC). Buffers are needed in routers to house incoming flits which cannot be immediately forwarded due to contention. This buffering can be done at the inputs or the outputs of a router, corresponding to an input-buffered router (IBR) or an output-buffered router (OBR). OBRs are attractive because they can sustain higher throughputs and have lower queuing delays under high loads than IBRs. However, a direct implementation of an OBR requires a router speedup equal to the number of ports, making such a design prohibitive under aggressive clocking needs and limited power budgets of most NoC applications. In this paper, we propose a new router design that aims to emulate an OBR practically, based on a distributed shared-buffer (DSB) router architecture. We introduce innovations to address the unique constraints of NoCs, including efficient pipelining and novel flow-control. We also present practical DSB configurations that can reduce the power overhead with negligible degradation in performance. The proposed DSB router achieves up to 19% higher throughput on synthetic traffic and reduces packet latency by 60% on average for SPLASH-2 benchmarks with high contention, compared to a state-of-art pipelined IBR. On average, the saturation throughput of DSB routers is within 10% of the theoretically ideal saturation throughput under the synthetic workloads evaluated.\",\n \"Title: Designing efficient codes for synchronization error channels\\nYear: 2011\\n\\nAbstract: For communications and networking channels, coding techniques are widely used to correct errors in corrupted messages. The \\\"Quality of Protection\\\" (QoP) that can be provided via error correction directly affects the \\\"Quality of Service\\\" (QoS) experienced by users. The errors are commonly assumed to be substitution or erasure errors. Such systems rely on perfect synchronization so that no bit is deleted and no extra bit is inserted. However, in a system without the presence of perfect synchronization, special coding algorithms may be required to correct potential insertion or deletion errors in transmitted messages. Especially for systems suffering from frequent loss of synchronization, packets may require many retransmissions to guarantee reliable communication. Such schemes may become too expensive to be practical. In this paper, we propose a new synchronization channel error model based on the observations from current communication systems. In this model, the channel introduces at most t synchronization errors in each run of the transmitted sequence. We present run-length limited permutation codes capable of correcting synchronization errors based on this channel error model. Compared to previously developed codes, our codes have the advantage of correcting frequent synchronization errors, and therefore they are suitable for disruptive network channels that suffer severe synchronization failures.\",\n \"Title: The interleaved matching switch architecture\\nYear: 2009\\n\\nAbstract: Operators need routers to provide service guarantees such as guaranteed flow rates and fairness among flows, so as to support traffic engineering and real-time traffic. However, current centralized input-queued router architectures cannot scale to fast line rates while providing these service guarantees. On the other hand, while load-balanced switch architectures that rely on two identical stages of fixed-configuration switches appear to be an effective way to scale Internet routers to very high capacities, there is currently no practical and scalable solution for providing service guarantees in these architectures. In this paper, we introduce the interleaved matching switch (IMS) architecture, which relies on a novel approach to provide service guarantees using load-balanced switches. The approach is based on emulating a Birkhoff-von Neumann switch with a load-balanced switch architecture and is applicable to any known admissible traffic. We show that service guarantees, 100% throughput, and packet ordering can be achieved with O(1) online complexity. In cases where fixed frame sizes are applicable, we also present an efficient offline frame-based decomposition method. More generally, we show that the IMS architecture can be used to emulate any input queued or combined input-output queued switch, leveraging a large body of known results for ensuring stability.\",\n \"Title: Control resynthesis for control-dominated asynchronous designs.\\nYear: 1996\\n\\nAbstract: Syntax directed translation based compilation from high-level concurrent programs has matured significantly over the past few years. They have been applied to significant designs in the domains of digital signal processing and microprocessor designs. For data-path dominated designs, like those found in digital signal processing applications, syntax directed translation approaches have been shown to generate efficient asynchronous implementations. However, for control-dominated designs where the data processing parts play a relatively minor role, we believe the solutions produced by pure syntax directed translation methods may be significantly improved. In this paper, we consider the problem of resynthesizing the control parts of the syntax directed translation solutions by means of STG based algorithmic synthesis approaches. This involves a strategy for partitioning between the control and data processing parts, algorithms for reconstructing the STGs from the control partitions, and a strategy for resynthesizing these reconstructed STGs using existing STG-based synthesis approaches. We show with a realistic design experiment that our control resynthesis approach can offer significant improvements over pure syntax directed translation solutions.\",\n \"Title: The Concurrent Matching Switch Architecture\\nYear: 2010\\n\\nAbstract: Network operators need high-capacity router architectures that can offer scalability, provide throughput guarantees, and maintain packet ordering. However, current centralized crossbar-based architectures cannot scale to fast line rates and high port counts. On the other hand, while load-balanced switch architectures that rely on two identical stages of fixed configuration meshes appear to be an effective way to scale Internet routers to very high capacities, they incur a large worst-case packet reordering that is at best quadratic to the switch size. In this paper, we introduce the concurrent matching switch (CMS) architecture, which also uses two identical stages of fixed configuration meshes with the same scalability properties as current load-balanced routers. However, by adopting a novel contention-resolution architecture that is scalable and distributed, the CMS architecture enforces packet ordering throughout the switch. Using the CMS architecture, we show that scalability, 100% throughput, packet ordering, and O(1) amortized time complexity with sequential hardware per linecard can all be achieved. We further demonstrate a delay analysis for the CMS architecture.\",\n \"Title: Synthesis of concurrent system interface modules with automatic protocol conversion generation\\nYear: 1994\\n\\nAbstract: We describe a new high-level compiler called Integral for designing system interface modules. The input is a high-level concurrent algorithmic specification that can model complex concurrent control flow, logical and arithmetic computations, abstract communication, and low-level behavior. For abstract communication between two communicating modules that obey different I/O protocols, the necessary protocol conversion behaviors are automatically synthesized using a Petri net theoretic approach. We present a synthesis trajectory that can synthesize the necessary hardware resources, control circuitry, and protocol conversion behaviors for implementing system interface modules.\",\n \"Title: An on-chip global broadcast network design with equalized transmission lines in the 1024-core era\\nYear: 2012\\n\\nAbstract: Based on current trends in multicore scaling, chips with 1024 cores may be available within the next decade. For such number of cores, cache coherence becomes a critical challenge because of the broadcasting operation. For the conventional electrical mesh interconnect network, broadcasting common data to all the cores is difficult to perform efficiently. In this paper, we developed a high-throughput, low-latency and power-efficient equalized dense transmission line (T-line) structure tailored for efficient global broadcasting. Moreover, we propose a hierarchical architecture and an efficient physical structure for 1024-core communication. Evaluation results show high performance of our solution.\",\n \"Title: A generalized signal transition graph model for specification of complex interfaces\\nYear: 1994\\n\\nAbstract: This paper introduces a new Generalized Signal Transition Graph model for specifying complex mixed asynchronous/synchronous circuits, as found in system-level interfaces. The goal has been to develop extensions that make it possible to model mixed asynchronous/synchronous and arbitration behavior. A number of key extensions have been developed that makes the model much more widely applicable to industrial designs. The extensions include Boolean guards, the introduction of level semantics that make it possible to describe “events” in terms of both signal transitions as well as “signal levels”, and the semantic extensions for describing don't care and undefined behavior. The latter extensions make it possible to model synchronous finite state machines using an asynchronous model, hence permitting the specification of mixed asynchronous/synchronous behavior. The proposed Generalized Signal Transition Graph Model is free from the restrictions of the previous models such as liveness, safeness, and free-choice requirements, and permits general Petri-net structures that may include multiple tokens in a place as long as the resulting state graph is bounded and has a consistent state assignment. A key aspect of the generalizations is that all the extensions are defined at the state graph level\",\n \"Title: On the impact of traffic statistics on quality of service for networks on chip\\nYear: 2005\\n\\nAbstract: Packet switched networks on chip (NoC) architectures have been proposed as a solution to the global interconnect problem in the nanoscale systems on chip (SoC) design era. An important design consideration for NoC, is silicon cost. Towards the goal of keeping the NoC simple, we pose the following question: under what traffic conditions will quality of service (QoS) be provided without the added complexity of an explicit QoS mechanism? In this paper, we take the first step towards answering this question by empirically analyzing different combinations of traffic patterns and injection processes. Specifically, we analyze the effects of different traffic on latency under two cases: (1) an NoC with no QoS mechanism (i.e. without distinction among different classes of service); and (2) an NoC with the simplest distinction into two classes of service: guaranteed service and best effort.\",\n \"Title: Basic gate implementation of speed-independent circuits\\nYear: 1994\\n\\nAbstract: Existing methods for synthesis of speed- independent circuits under unbounded delay model have diffi- culties in combining the generality of formal approach with the practicality of the implementation architectures used at the logic level. This paper presents a characteristic property of the state graph specification, called Monotonous Cover requirement, im- plying its hazard-free implementation within the standard struc- ture of a two-level SOP logic and a row of latches. The overall synthesis procedure ensures satisfiability of this condition by ap- plying the generalised state assignment approach. I INTRODUCTION The design of asynchronous circuitry is a difficult task since circuit malfunction can occur during execution if it is not free of hazards. One approach is based on bounded gate/wire de- lay assumptions and relies on delay information to eliminate hazards (7), which means the implementation is not robust to delay variations due to differences in process technologies or noise and temperature variations. In this paper, we consider the problem of producing speed-independent asynchronous circuits using only basic gates such as AND-gates, OR-gates, and asynchronous latches. Speed-independence means that the circuit will work correctly regardless of the individual gate delays. This is known as the unbounded gate delay model. It assumes that the wires can also have arbitrary delays, but the skew of all wire delays at multiple fanouts be negligible (less than the minimum gate delay). Speed-independent re- alizations are particularly attractive because they can tolerate delay variations that are inevitable when migrating to different process technologies or even with a known technology un- der process or temperature variations. This also implies that speed-independent modules can easily be replaced whenever a higher performance process technology becomes available. There has been considerable research on the theory and automated synthesis of speed-independent circuits using com- plex gates (3, 8, 12). This theory is based on the assumptions that each non-input signal of a correct specification, which is either a Signal Transition Graph or semimodular State Graph, is implemented with a single complex gate and that this com- plex gate contains no internal hazards. It has been shown that the requirement of Complete State Coding(CSC) is the necessary and sufficient condition for such a complex gate implementation (3). However, it is often the case that the re- quired combinational logic functions are too complex to have single complex gate implementations from a standard library. Thus, researchers have investigated the problem of synthesiz- ing speed-independent circuits that assumes only the availabil- ity of basic gates such as AND-gates and OR-gates. However,\",\n \"Title: A Scalable Switch for Service Guarantees\\nYear: 2005\\n\\nAbstract: Operators need routers to provide service guarantees such as guaranteed flow rates and fairness among flows, so as to support real-time traffic and traffic engineering. However, current centralized input-queued router architectures cannot scale to fast line rates while providing these service guarantees. On the other hand, while load-balanced switch architectures that rely on two identical stages of fixed configuration switches appear to be an effective way to scale Internet routers to very high capacities, there is currently no practical and scalable solution for providing service guarantees in these architectures. In this paper, we introduce the interleaved matching switch (IMS) architecture, which relies on a novel approach to provide service guarantees using load-balanced switches. The approach is based on emulating a Birkhoff-von Neumann switch with a load-balanced switch architecture and is applicable to any admissible traffic. In cases where fixed frame sizes are applicable, we also present an efficient frame-based decomposition method. More generally, we show that the IMS architecture can be used to emulate any input queued or combined input-output queued switch.\",\n \"Title: Minimizing collateral damage by proactive surge protection\\nYear: 2007\\n\\nAbstract: Existing mechanisms for defending against distributed denial-of-service (DDoS) attacks are generally reactive in nature. However, the onset of large-scale bandwidth-based attacks can occur suddenly, potentially knocking out substantial parts of a network before reactive defenses can respond. Even for traffic flows that are not under direct attack, significant collateral damage will result if these flows pass through links that are common to attack routes. This paper presents a proactive-surge-protection (PSP) mechanism that aims to provide a broad first line of defense against DDoS attacks. Our solution aims to minimize collateral damage by providing bandwidth isolation between traffic flows. This isolation is achieved through a combination of traffic forecasting, proportional allocation of network capacity, metering and tagging of packets at the network perimeter, and preferential dropping of packets inside the network. Our solution is readily deployable using existing router mechanisms. Simulations across three large backbone networks show that up to 95.5% of the network could suffer collateral damage without protection, but our solution was able to reduce the amount of collateral damage by 60.5-97.8%, even with a coarse-grained forecasting scheme.\",\n \"Title: Constructing application-specific heterogeneous embedded architectures from custom HW/SW applications\\nYear: 1996\\n\\nAbstract: Deep sub-micron processing technologies have enabled the imple- mentation of new application-specific embedded architecturesthat in- tegrate multiple software programmable processors (e.g. DSPs, mi- crocontrollers) and dedicated hardware components together onto a single cost-efficient IC. These application-specific architectures are emerging as a key design solution to today's microelectronics design problems, which are being driven by emerging applications in the ar- eas of wireless communication, broadband networking, and mu ltime- dia computing. However, the construction of these customized hetero- geneous multiprocessor architectures, while ensuring that the hard- ware and software parts communicate correctly, is a tremendously difficult and highly error proned task with little or no tool s upport. In this paper, we present a solution to this embedded architecture co- synthesis problem based on an orchestrated combination of architec- tural strategies, parameterized libraries, and software tool support.\",\n \"Title: Power estimation methods for sequential logic circuits\\nYear: 1995\\n\\nAbstract: Recently developed methods for power estimation have primarily focused on combinational logic. We present a framework for the efficient and accurate estimation of average power dissipation in sequential circuits. Switching activity is the primary cause of power dissipation in CMOS circuits. Accurate switching activity estimation for sequential circuits is considerably more difficult than that for combinational circuits, because the probability of the circuit being in each of its possible states has to be calculated. The Chapman-Kolmogorov equations can be used to compute the exact state probabilities in steady state. However, this method requires the solution of a linear system of equations of size 2/sup N/ where N is the number of flip-flops in the machine. We describe a comprehensive framework for exact and approximate switching activity estimation in a sequential circuit. The basic computation step is the solution of a nonlinear system of equations which is derived directly from a logic realization of the sequential machine. Increasing the number of variables or the number of equations in the system results in increased accuracy. For a wide variety of examples, we show that the approximation scheme is within 1-3% of the exact method, but is orders of magnitude faster for large circuits. Previous sequential switching activity estimation methods can have significantly greater inaccuracies.<>\",\n \"Title: Derivation of formal representations from process-based specification and implementation models\\nYear: 1997\\n\\nAbstract: In this paper we present a method that allows to observe and control the emulation of communicating systems consisting of hardware and software parts. The approach provides the ability to set breakpoints in either technology without breaking the protocol or loosing data. Systems may contain several software and hardware processes. Each process runs in a separate debugger while the presented approach provides the necessary synchronization between the processes that precludes loss of data at the communication interfaces due to breakpoints. Therefore it allows to continue the operation after a breakpoint which is essential for interactive debugging.\",\n \"Title: Fast and Scalable Priority Queue Architecture for High-Speed Network Switches\\nYear: 2000\\n\\nAbstract: In this paper, we present a fast and scalable pipelined priority queue architecture for use in high-performance switches with support for fine-grained quality of service (QoS) guarantees. Priority queues are used to implement highest-priority-first scheduling policies. Our hardware ar- chitecture is based on a new data structure called a Pipelined heap, or P-heap for short. This data structure enables the pipelining of the enqueue and dequeue operations, thereby allowing these operations to execute in essentially constant time. In addition to being very fast, the architecture also scales very well to a large number of priority levels and to large queue sizes. We give a detailed description of this new data structure, the asso- ciated algorithms and the corresponding hardware implementation. We have implemented this new architecture using a 0.35 micron CMOS tech- nology. Our current implementation can support 10 Gb/s connections with over 4 billion priority levels .\",\n \"Title: Reservation-Based Packet Bufferswith Deterministic Packet Departures\\nYear: 2014\\n\\nAbstract: High-performance routers need to temporarily store a large number of packets in response to congestion. DRAM is typically needed to implement large packet buffers, but the worst-case random access latencies of DRAM devices are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into two categories: prefetching-based and randomization-based. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. In this paper, we describe novel reservation-based packet buffer architectures with interleaved memories that take advantage of the known packet departure times to achieve simplicity and determinism. The number of interleaved DRAM banks required to implement the proposed packet buffer architectures is independent of the number of logical queues, yet the proposed architectures can achieve the performance of an SRAM implementation. Our reservation-based solutions are scalable to growing packet storage requirements in routers while matching increasing line rates.\",\n \"Title: Embedded architecture co-synthesis and system integration\\nYear: 1996\\n\\nAbstract: Embedded system architectures comprising of software programmable components (e.g. DSP, ASIP, and micro-controller cores) and customized hardware co-processors, integrated into a single cost-efficient VLSI chip, are emerging as a key solution to today's microelectronics design problems. This trend is being driven by new emerging applications in the areas of wireless communication, high-speed optical networking, and multimedia computing. A key problem confronted by embedded system designers today is the rapid prototyping of application-specific embedded system architectures where different combinations of programmable processors and hardware components must be integrated together, while ensuring that the hardware and software parts communicate correctly. In this paper, we present a solution to this embedded architecture co-synthesis and system integration problem based on an orchestrated combination of architectural strategies, parameterized libraries, and software CAD tools\",\n \"Title: A novel 3D layer-multiplexed on-chip network\\nYear: 2009\\n\\nAbstract: Recently, a near-optimal oblivious routing algorithm for 3D mesh networks called Randomized Partially-Minimal (RPM) routing was proposed [12], which works by load-balancing traffic across vertical layers and routing minimally on each horizontal layer. It achieves optimal worst-case throughput when the network radix k is even and within a factor of 1/k2 of optimal when k is odd, and it achieves significantly lower latencies than Valiant routing [18], the best previously known optimal worst-case throughput algorithm. This paper presents a novel layer-multiplexed (LM) architecture for 3D on-chip networks that exploits the optimality of RPM together with the short inter-layer wiring delays enabled in 3D technology. The LM architecture replaces the one-layer-per-hop routing in a 3D mesh with simpler vertical demultiplexing and multiplexing structures. The proposed LM architecture can achieve the same worst-case throughput as a 3D mesh by adapting RPM routing to the LM architecture. However, the LM architecture consumes 27% less power, occupies 27% less area, attains 14.5% higher average throughput, and achieves 33% lower worst-case hop count for a symmetric 4x4x4 mesh topology. On an asymmetric 8 x 8 x 4 mesh, the LM architecture achieves comparable average-case throughput to a 3D mesh, but consumes 26% less power, takes up 27% less area and attains 20% lower worst-case hop count.\",\n \"Title: Birkhoff-von Neumann switching with statistical traffic profiles\\nYear: 2010\\n\\nAbstract: Offline scheduling is attractive when the traffic profile is known a priori since the complexity of online scheduling is largely removed. Given any admissible rate matrix @L=(@l\\\"i\\\"j), Birkhoff-von Neumann decomposition offers a quasi-offline scheduling strategy that can provide a service rate of at least @l\\\"i\\\"j for each flow (i,j) without internal speedup. This paper extends the Birkhoff-von Neumann switching strategy to consider traffic profiles in which the traffic demands are specified as statistical distributions rather than fixed rates.\",\n \"Title: Design of High-Speed Packet Switch with Fine-Grained Quality-of-Service Guarantees\\nYear: 2000\\n\\nAbstract: We present a new input-queued switch architecture designed to support deadline-ordered scheduling at extremely high-speeds. In particular, deadline-ordered scheduling is enabled through a combination of hardware-based sorted priority queues called P-heaps and a round-robin crossbar scheduler. The priority queues are implemented using a novel scalable pipelined heap-based architecture. Using a 0.35 micron CMOS standard-cell technology, we demonstrate a 32-port switch capable of sustaining 10 Gb/s line rates.\",\n \"Title: Flow Graph Balancing for Minimizing the Required Memory Bandwidth\\nYear: 1996\\n\\nAbstract: In this paper we present the problem of flow graph balancing for minimizing the required memory bandwidth. Our goal is to minimize the required memory bandwidth within the given cycle budget by adding ordering constraints to the flow graph. This allows the subsequent memory allocation and assignment tasks to come up with a cheaper memory architecture with less memories and memory ports. The effect of flow graph balancing is shown on an example. We show that it is important to take into account which data is being accessed in parallel, instead of only considering the number of simultaneous memory accesses. This leads to the optimization of a conflict graph.\",\n \"Title: Joint multicast routing and network design optimisation for networks-on-chip\\nYear: 2009\\n\\nAbstract: In this study, we consider the problem of synthesising custom networks-on-chip (NoC) architectures that are optimised for a given application. Both unicast and multicast traffic flows are considered in the input specification. We formulate the joint multicast routing and network design problem using a rip-up and reroute procedure, where each multicast routing step is formulated as a minimum direct...\",\n \"Title: Rank-indexed hashing: A compact construction of Bloom filters and variants\\nYear: 2008\\n\\nAbstract: Bloom filter and its variants have found widespread use in many networking applications. For these applications, minimizing storage cost is paramount as these filters often need to be implemented using scarce and costly (on-chip) SRAM. Besides supporting membership queries, Bloom filters have been generalized to support deletions and the encoding of information. Although a standard Bloom filter construction has proven to be extremely space-efficient, it is unnecessarily costly when generalized. Alternative constructions based on storing fingerprints in hash tables have been proposed that offer the same functionality as some Bloom filter variants, but using less space. In this paper, we propose a new fingerprint hash table construction called Rank-Indexed Hashing that can achieve very compact representations. A rank-indexed hashing construction that offers the same functionality as a counting Bloom filter can be achieved with a factor of three or more in space savings even for a false positive probability of just 1%. Even for a basic Bloom filter function that only supports membership queries, a rank-indexed hashing construction requires less space for a false positive probability as high as 0.1%, which is significant since a standard Bloom filter construction is widely regarded as extremely space-efficient for approximate membership problems.\",\n \"Title: DRAM is plenty fast for wirespeed statistics counting\\nYear: 2008\\n\\nAbstract: Per-flow network measurement at Internet backbone links requires the efficient maintanence of large arrays of statistics counters at very high speeds (e.g. 40 Gb/s). The prevailing view is that SRAM is too expensive for implementing large counter arrays, but DRAM is too slow for providing wirespeed updates. This view is the main premise of a number of hybrid SRAM/DRAM architectural proposals [2, 3, 4, 5] that still require substantial amounts of SRAM for large arrays. In this paper, we present a contrarian view that modern commodity DRAM architectures, driven by aggressive performance roadmaps for consumer applications (e.g. video games), have advanced architecture features that can be exploited to make DRAM solutions practical. We describe two such schemes that can harness the performance of these DRAM offerings by enabling the interleaving of counter updates to multiple memory banks. These counter schemes are the first to support arbitrary increments and decrements for either integer or floating point number representations at wirespeed. We believe our preliminary success with the use of DRAM schemes for wirespeed statistics counting opens the possibilities for broader research opportunities to generalize the proposed ideas for other network measurement functions.\",\n \"Title: LEISURE: Load-Balanced Network-Wide Traffic Measurement and Monitor Placement\\nYear: 2015\\n\\nAbstract: Network-wide traffic measurement is of interest to network operators to uncover global network behavior for the management tasks of traffic accounting, debugging or troubleshooting, security, and traffic engineering. Increasingly, sophisticated network measurement tasks such as anomaly detection and security forensic analysis are requiring in-depth fine-grained flow-level measurements. However, performing in-depth per-flow measurements (e.g., detailed payload analysis) is often an expensive process. Given the fast-changing Internet traffic landscape and large traffic volume, a single monitor is not capable of accomplishing the measurement tasks for all applications of interest due to its resource constraint. Moreover, uncovering global network behavior requires network-wide traffic measurements at multiple monitors across the network since traffic measured at any single monitor only provides a partial view and may not be sufficient or accurate. These factors call for coordinated measurements among multiple distributed monitors. In this paper, we present a centralized optimization framework, LEISURE (Load-EqualIzed meaSUREment), for load-balancing network measurement workloads across distributed monitors. Specifically, we consider various load-balancing problems under different objectives and study their extensions to support both fixed and flexible monitor deployment scenarios. We formulate the latter flexible monitor deployment case as an MILP (Mixed Integer Linear Programming) problem and propose several heuristic algorithms to approximate the optimal solution and reduce the computation complexity. We evaluate LEISURE via detailed simulations on Abilene and GEANT network traces to show that LEISURE can achieve much better load-balanced performance (e.g., 4.75× smaller peak workload and 70× smaller variance in workloads) across all coordinated monitors in comparison to a naive solution (uniform assignment) to accomplish network-wide traffic measure- ent tasks under the fixed monitor deployment scenario. We also show that under the flexible monitor deployment setting, our heuristic solutions can achieve almost the same load-balancing performance as the optimal solution while reducing the computation times by a factor up to 22.5× in Abilene and 800× in GEANT.\",\n \"Title: ORION3.0: A Comprehensive NoC Router Estimation Tool\\nYear: 2015\\n\\nAbstract: Networks-on-Chip (NoCs) are increasingly used in many-core architectures. ORION2.0 [1] is a widely adopted NoC power and area estimation tool, but its estimation models can have large errors (up to 185%) versus actual implementations. We present ORION3.0, an open-source tool whose parametric and non-parametric modeling methodologies fundamentally differ from ORION2.0 logic template-based approaches in that the estimation models are derived from actual physical implementation data. When compared with actual implementations, ORION3.0 models achieve average estimation errors of no more than 9.3% across microarchitecture, implementation, and operational parameters as well as multiple router RTL generators. A comprehensive suite of these methodologies has been implemented in ORION3.0 [2].\",\n \"Title: Revisiting State Blow-Up: Automatically Building Augmented-FA While Preserving Functional Equivalence\\nYear: 2014\\n\\nAbstract: Regular expression matching, a central task in deep packet inspection and other networking applications, has been traditionally implemented through finite automata. Thanks to their limited per-character processing and memory bandwidth requirements, deterministic finite automata (DFA) are a natural choice for memory-based implementations. In the presence of large datasets of complex patterns, however, DFA suffer from the well-known state explosion problem. Specifically, state explosion can take place during DFA generation when the considered patterns contain bounded and unbounded repetitions of wildcards or large character sets. Several alternative FA representations have been proposed to address this problem. However, these proposals all suffer from one or more of the following problems: some can avoid state explosion only on datasets of limited size and complexity; some have prohibitive worst-case memory bandwidth requirements or processing time; and some can only guarantee functional equivalence for restricted classes of regular expressions and require the user to manually filter out unsupported patterns. In this work we propose JFA, a finite automation that uses state variables to avoid state explosion, and is functionally equivalent to the corresponding DFA. Functional equivalence is guaranteed by construction without requiring user intervention. We also provide optimization techniques to both limit the amount of state variables required and provide a lower bound for the JFA traversal time.\",\n \"Title: Sprinklers: A Randomized Variable-Size Striping Approach to Reordering-Free Load-Balanced Switching.\\nYear: 2014\\n\\nAbstract: Internet traffic continues to grow exponentially, calling for switches that can scale well in both size and speed. While load-balanced switches can achieve such scalability, they suffer from a fundamental packet reordering problem. Existing proposals either suffer from poor worst-case packet delays or require sophisticated matching mechanisms. In this paper, we propose a new family of stable load-balanced switches called \\\"Sprinklers\\\" that has comparable implementation cost and performance as the baseline load-balanced switch, but yet can guarantee packet ordering. The main idea is to force all packets within the same virtual output queue (VOQ) to traverse the same ``fat path'' through the switch, so that packet reordering cannot occur. At the core of Sprinklers are two key innovations: a randomized way to determine the \\\"fat path\\\" for each VOQ, and a way to determine its \\\"fatness\\\" roughly in proportion to the rate of the VOQ. These innovations enable Sprinklers to achieve near-perfect load-balancing under arbitrary admissible traffic. Proving this property rigorously using novel worst-case large deviation techniques is another key contribution of this work.\",\n \"Title: Minimization of symbolic relations\\nYear: 1990\\n\\nAbstract: The problem of minimizing symbolic relations is addressed. The relevance of this problem in the field of optimal encoding is shown by examples. A binate covering formulation of the optimization problems involved is given, for which several algorithms are available. A novel method is proposed which is based on binary decision diagrams (BDDs) and the authors show how the covering problem can be solved in linear time in that case.<>\",\n \"Title: Implicit manipulation of equivalence classes using binary decision diagrams\\nYear: 1991\\n\\nAbstract: A novel representation called an equivalence class characterization function is defined. It can implicitly represent all equivalence classes with a compact characteristic function that will have at most n outputs. Using binary decision diagrams (BDDs) and the concept of the equivalence class characterization function, very large problem instances can be represented. For manipulating equivalence classes efficiently, a Boolean operator called a compatible projection operator is proposed. Conceptually, the compatible projection operator is used to uniquely select a single element from each equivalence class to characterize the class. In manipulating equivalence classes, the compatible projection operator is used to implicitly derive an encoding function from the equivalence relation that encodes the equivalence class information symbolically. An efficient implementation is described based on BDDs that is applied to very large problem instances\",\n \"Title: Symbolic hazard-free minimization and encoding of asynchronous finite state machines\\nYear: 1995\\n\\nAbstract: This paper presents an automated method for the synthesis of multiple-input-change (MIC) asynchronous state machines. Asynchronous state machine design is subtle since, unlike synchronous synthesis, logic must be implemented without hazards, and state codes must be chosen carefully to avoid critical races. We formulate and solve an optimal hazard-free and critical race-free encoding problem for a class of MIC asynchronous state machines called burst-mode. Analogous to a paradigm successfully used for the optimal encoding of synchronous machines, the problem is formulated as an input encoding problem. Implementations are targeted to sum-of-product realizations. We believe this is the first general method for the optimal encoding of hazard-free MIC asynchronous state machines under a generalized fundamental mode of operation. Results indicate that improved solutions are produced, ranging up to 17% improvement.\",\n \"Title: Efficient partial enumeration for timing analysis of asynchronous systems\\nYear: 1996\\n\\nAbstract: This paper presents an efficient method for the timing verification of concurrent systems, modeled as labeled Timed Petri nets. The verification problems we consider re- quire us to analyze the system's reachable behaviors under the specified time delays. Ourgeometric timing analysis algo- rithm improves over existing ones by enumerating the state space onlypartially. The algorithm relies on a concept called pre-mature firingand a new, extended notion of clocks with a negative age. We have tested the fully automated proce- dure on a number of examples. Experimental results obtained on highly concurrent Petri nets with more than 6000 nodes and reachable states show that the proposed method can drastically reduce computational cost. I Introduction\",\n \"Title: Hardware/software co-design of digital telecommunication systems\\nYear: 1997\\n\\nAbstract: We reflect on the nature of digital telecommunication systems. We argue that these systems require, by nature, a heterogeneous specification and an implementation with heterogeneous architectural styles. CoWare is a hardware/software co-design environment based on a data model that allows to specify, simulate, and synthesize heterogeneous hardware/software architectures from a heterogeneous specification. CoWare is based on the principle of encapsulation of existing hardware and software compilers and special attention is paid to the interactive synthesis of hardware/software and hardware/hardware interfaces. The principles of CoWare are illustrated by the design process of a spread-spectrum receiver for a pager system\",\n \"Title: Externally hazard-free implementations of asynchronous control circuits\\nYear: 1997\\n\\nAbstract: We present a new sum-of-product-based asynchronous architecture, called the N-SHOT architecture, that operates correctly under internal hazardous responses and guarantees hazard-freeness at the observable noninput signals. We formally prove that within this architecture, a very wide class of semimodular state graphs with input choices (either distributive or nondistributive) that satisfy the complete state coding property always admit a correct implementation, As with synchronous circuits, we permit internal hazards in the combinational logic core, which means that we can make use of conventional combinational logic minimization methods to produce the sum-of-product implementation. This represents a significant departure from most existing methods that require the combinational logic to be hazard-free and are mainly valid for distributive behaviors, We also present optimizations for this architecture which are related to state graph properties\",\n \"Title: A Methodology for Efficient Estimation of Switching Activity in Sequential Logic Circuits\\nYear: 1994\\n\\nAbstract: We describe a computationally efficient scheme to approximate average switching activity in sequential circuits which requires the solution of a non-linear system of equations of size N, where the variables correspond to state line probabilities. We show that the approximation method is within 3% of the exact Chapman-Kolmogorov method, but is orders of magnitude faster for large circuits. Previous sequential switching activity estimation methods can have significantly greater inaccuracies.\",\n \"Title: Fast Buffer Memory with Deterministic Packet Departures\\nYear: 2006\\n\\nAbstract: High-performance routers need to store temporarily a large number of packets in response to congestion. DRAM is typically used to implement the needed packet buffers, but DRAM devices are too slow to match the bandwidth requirements. To bridge the bandwidth gap, a number of hybrid SRAM/DRAM packet buffer architectures have been proposed (S. Iyer and N. Mckeown, 2002) (S. Kumar et al., 2005). These packet buffer architectures assume a very general model where the buffer consists of many logically separated FIFO queues that may be accessed in random order. For example, virtual output queues (VOQs) are used in crossbar routers, where each VOQ corresponds to a logical queue corresponding to a particular output. Depending on the scheduling algorithm used, the access pattern to these logical queues may indeed be at random. However, for a number of router architectures, this worst-case random access assumption is unnecessary since packet departure times are deterministic. One architecture is the switch-memory-switch router architecture (A. Prakash et al., 2002) (S. Iyer et al., 2002) that efficiently mimics an output queueing switch. Another architecture is the load-balanced router architecture (C.S. Chang et al., 2002) (I. Keslassy et al., 2003) that has interesting scalability properties. In these architectures, for best-effort routing, the departure times of packets can be deterministically calculated before inserting packets into packet buffers. In this paper, we describe a novel packet buffer architecture based on interleaved memories that takes advantage of the known packet departure times to achieve simplicity and determinism. The number of interleaved DRAM banks required to implement the proposed packet buffer architecture is independent of the number of logical queues, yet the proposed architecture can achieve the performance of an SRAM implementation\",\n \"Title: Near-optimal oblivious routing on three-dimensional mesh networks\\nYear: 2008\\n\\nAbstract: The increasing viability of three dimensional (3D) silicon integration technology has opened new opportunities for chip architecture innovations. One direction is in the extension of two-dimensional (2D) mesh-based tiled chip-multiprocessor architectures into three dimensions. In this paper, we focus on efficient routing algorithms for such 3D mesh networks. As in the case of 2D mesh networks, throughput and latency are important design metrics for routing algorithms. Existing routing algorithms suffer from either poor worst-case throughput (DOR , ROMM) or poor latency (VAL). Although the minimal routing algorithm O1TURN proposed in already achieves near-optimal worst-case throughput for the 2D case, the optimality result does not extend to higher dimensions. For 3D and higher dimensional meshes, the worst-case throughput of O1TURN degrades tremendously. The main contribution of this paper is the design of a new oblivious routing algorithm for 3D mesh networks called randomized partially-minimal (RPM) routing. RPM provably achieves optimal worst-case throughput for 3D meshes when the network radix k is even and within a factor of 1/k2 of optimal worst-case throughput when k is odd. RPM also outperforms VAL, DOR, ROMM, and O1TURN in average-case throughput by 33.3%, 111%, 47%, and 30%, respectively when averaged over one million random traffic patterns on an 8 times 8 times 8 topology. Finally, whereas VAL achieves optimal worst-case throughput at a penalty factor of 2 in average latency over DOR, RPM achieves (near) optimal worst-case throughput with a much smaller factor of 1.33. In practice, the average latency of RPM is expected to be closer to minimal routing because 3D mesh networks are not expected to be symmetric in 3D chip designs. The number of available device layers is expected to be much less than the number of processor tiles that can be placed along an edge of a device layer. For practical asymmetric 3D mesh configurations, the average laten- - cy of RPM reduces to just a factor of 1.11 of DOR.\",\n \"Title: Randomized Partially-Minimal Routing: Near-Optimal Oblivious Routing for 3-D Mesh Networks\\nYear: 2012\\n\\nAbstract: The increasing viability of 3-D silicon integration technology has opened new opportunities for chip architecture innovations. One direction is in the extension of 2-D mesh-based tiled chip-multiprocessor architectures into three dimensions. This paper focuses on efficient routing algorithms for such 3-D mesh networks. Existing routing algorithms suffer from either poor worst-case throughput (DOR, ROMM) or poor latency (VAL). Although the minimal routing algorithm O1TURN proposed in already achieves near-optimal worst-case throughput for 2-D mesh networks, the optimality result does not extend to higher dimensions. For 3-D and higher dimensional meshes, the worst-case throughput of O1TURN degrades tremendously. The main contribution of this paper is a new oblivious routing algorithm for 3-D mesh networks called randomized partially-minimal (RPM) routing. RPM provably achieves optimal worst-case throughput for 3-D meshes when the network radix k is even and within a factor of 1/k2 of optimal worst-case throughput when k is odd. Finally, whereas VAL achieves optimal worst-case throughput at a penalty factor of 2 in average latency over DOR, RPM achieves (near) optimal worst-case throughput with a much smaller factor of 1.33. For practical asymmetric 3-D mesh configurations where the number of device layers are fewer than the number of tiles along the edge of a layer, the average latency of RPM reduces to just a factor of 1.11 to 1.19 of DOR. Additionally, a variant of RPM called randomized minimal first (RMF) routing is proposed, which leverages the inherent load-balancing properties of the network traffic to further reduce packet latency without compromising throughput.\",\n \"Title: Optimal multi-path routing and bandwidth allocation under utility max-min fairness\\nYear: 2009\\n\\nAbstract: An important goal of bandwidth allocation is to maximize the utilization of network resources while sharing the resources in a fair manner among network flows. To strike a bal- ance between fairness and throughput, a widely studied criterion in the network community is the notion of max-min fairness. However, the majority of work on max-min fairness has been limited to the case where the routing of flows has already been defined and this routing is usually based on a single fixed routing path for each flow. In this paper, we consider the more general problem in which the routing of flows, possibly over multiple paths per flow, is an optimization parameter in the bandwidth allocation problem. Our goal is to determine a routing assignment for each flow so that the bandwidth allocation achieves optimal utility max-min fairness with respect to all feasible routings of flows. We present evaluations of our proposed multi-path utility max-min fair allocation algorithms on a statistical traffic engi- neering application to show that significantly higher minimum utility can be achieved when multi-path routing is considered simultaneously with bandwidth allocation under utility max- min fairness, and this higher minimum utility corresponds to significant application performance improvements.\",\n \"Title: Efficient trace-driven metaheuristics for optimization of networks-on-chip configurations\\nYear: 2010\\n\\nAbstract: As industry moves towards many-core chips, networks-on-chip (NoCs) are emerging as a scalable communication fabric for interconnecting the cores. With increasing core counts, there is a corresponding increase in communication demands in multi-core designs to facilitate high core utilization, and a consequent critical need for high-performance NoCs. Another megatrend in advanced technologies is that power has become the most critical design constraint. In this paper, we focus on trace-driven virtual channel (VC) allocation in application-specific NoCs. We propose a new significant VC failure metric to capture the impact of VCs on network performance and efficiently drive NoC optimization. Our proposed metaheuristics achieve up to 38% reduction in the number of VCs under a given average packet latency constraint. In addition, compared to a recently proposed trace-driven VC allocation approach [13], we obtain up to an O(|L|) speedup, where |L| is total number of links in the network, with no degradation in the quality of results.\",\n \"Title: Improved on-chip router analytical power and area modeling\\nYear: 2010\\n\\nAbstract: Over the course of this decade, uniprocessor chips have given way to multi-core chips which have become the primary building blocks of today's computer systems. The presence of multiple cores on a chip shifts the focus from computation to communication as a key bottleneck to achieving performance improvements. As industry moves towards many-core chips, networks-on-chip (NoCs) are emerging as the scalable fabric for interconnecting the cores. With power now the first-order design constraint, early-stage estimation of NoC power has become crucially important. Existing power models (e.g., ORION 2.0 [12], Xpipes [7], etc.) are based on certain router microarchitecture and circuit implementation. Therefore, when validated against different NoC prototypes - different router implementations -- we saw significant deviation (up to 40% on average) that can lead to erroneous NoC design choices. This has prompted our development of a new, accurate architecture- and circuit implementation-independent router power and area modeling methodology with complete portability across existing NoC component libraries. Also, validation against a range of implemented router designs confirms substantial improvement in accuracy over existing models.\",\n \"Title: Frame-based multicast switching\\nYear: 2010\\n\\nAbstract: This letter considers the multicast scheduling problem for the case where the average rates of flows are known and a fixed frame size is applicable. We present a frame-based decomposition method for computing offline a recurring schedule that can guarantee the specified flow rates with minimum internal speedup, if any. We consider both the no-splitting case, where a multicast cell must be transferred to all its destinations in a single time slot, and the fanout-splitting case, where a multicast cell may take multiple time slots to transfer to all its destinations, transferring only to a subset of its destinations each time.\",\n \"Title: High-dimensional metamodeling for prediction of clock tree synthesis outcomes\\nYear: 2013\\n\\nAbstract: Clock tree synthesis (CTS) is a key aspect of on-chip interconnect, and major consumer of IC power and physical design resources. In modern sub-28nm tools and flows, it has become exceptionally difficult to satisfy skew, insertion delay and transition time constraints within power and area budgets, in part because commercial tools (with their many knobs) have become highly complex. This complexity, along with the complicated structure of real-world CTS instances (hierarchy, dividers, etc.) and floorplan contexts (aspect ratios, obstacles, etc.) make it very difficult to predict skew, power and other important metrics of CTS outcomes. In this work, we study CTS estimation in the high-dimensional parameter space of instance constraints and floorplan contexts. Using two leading commercial CTS tools as our testbed, we develop predictors, classifiers and “field of use” characterizations that can enable IC design teams to achieve required CTS solution quality through understanding of appropriate parameter subspaces. Our hierarchical hybrid surrogate modeling approach mitigates challenges of parameter multicollinearity in high dimensions. It achieves, e.g., worst-case estimation errors of 13% in contrast to 30% errors in [17]. We demonstrate use of a 94%-accurate “oracle” classifier and estimation models to predictably achieve CTS outcomes that meet specified constraints and target metrics.\",\n \"Title: A Simple Mechanism For Throttling High-Bandwidth Flows\\nYear: 2008\\n\\nAbstract: This letter presents BREATHe, a simple packet dropping scheme for identifying and throttling unresponsive or misbehaving highbandwidth flows during times of congestion. BREATHe is different from the existing active queue management techniques in that it uses heavy-hitter set analysis to identify highbandwidth flows rather than sampling or rate estimation. Specifically, BREATHe uses heavy-hitter set analysis to detect highbandwidth flows that exceed some target rate rlimit and preferentially drop packets from these flows. We show that the proposed mechanism is effective at throttling high-bandwidth flows using a small amount of state and low-complexity operation. Copyright (C) 2008 C.-W. Chang and B. Lin.\",\n \"Title: Modeling and optimization of hierarchical synchronous circuits\\nYear: 1995\\n\\nAbstract: Synchronous designs are often described and implemented hierarchically as a network of interacting finite state machines. When the individual components are synthesized and implemented separately, it is desirable to take into account the degrees of freedom that arise from the interactions with the other components and from the specification. Specifically, we consider the problem of finding the complete set of implementations that can be correctly substituted for a component in a system without changing the behavior of the total system. In this paper, a synchronous trace set model is proposed to tackle this problem. The unambiguous way in which this model describes synchronous behavior provides us with a general method to model interacting finite state machines. We show that a single synchronous trace set can be used to characterize all possible substitutions in a correct substitution problem. We give a necessary notion of progress that permits us to choose a correct one from this set, or to show that no solution exists. We provide results of an implicit implementation of our approach applied to benchmarks ranging from small to very large state machines. These results show the feasibility of the proposed methods.\",\n \"Title: System design tools for broadband telecom network applications\\nYear: 1996\\n\\nAbstract: Outlines a design methodology for the design of hybrid software/hardware systems that are typically found in telecom network applications. This methodology is based on the results of an investigation and evaluation of an actual industrial system application for ATM (Asynchronous Transfer Mode) based broadband networks at Alcatel Bell. As a result of this investigation, we have developed a system design methodology based on a concurrent object-oriented programming model as the system behavioral specification formalism. For implementation, we provide automated design tools for transforming the system level model into the traditional levels of design entries for hardware and software implementation. In particular, conventional C++ and VHDL models are generated for the parts of the system to be implemented in software and hardware, respectively. New system-level synthesis functionalities are required to achieve these automations. It is important to note that traditional hardware and software design methods, mostly commercially available, are used in our design flow, thereby not reinventing new solutions where adequate ones already exist. The work outlined in this presentation is embodied in a system design compiler called Matisse.\",\n \"Title: Single-tier virtual queuing: an efficacious memory controller architecture for MPSoCs with multiple realtime cores.\\nYear: 2016\\n\\nAbstract: In heterogeneous MPSoCs, memory interference between the CPU and realtime cores is a critical impediment to system performance. Previous memory schedulers adopt the classic two-tier queuing system, but unfortunately the use of two-tier queuing deteriorates the QoS of scheduling policies. In this paper, we propose the Single-Tier Virtual Queuing (STVQ) memory controller for efficacious QoS-aware scheduling. The STVQ memory controller maintains single-tier transaction queues and employs separable allocation for transaction scheduling with high scalability. A multi-source realtime scheduling algorithm is further presented. The STVQ controller achieves up to 13.9% less CPU IPC slowdown than previous schedulers with no frame rate penalty on realtime cores.\",\n \"Title: Safe Randomized Load-Balanced Switching by Diffusing Extra Loads.\\nYear: 2017\\n\\nAbstract: Load-balanced switch architectures are known to be scalable in both size and speed, which is of interest due to the continued exponential growth in Internet traffic. However, the main drawback of load-balanced switches is that packets can depart out of order from the switch. Randomized load-balancing of application flows by means of hashing on the packet header is a well-known simple solution to this packet reordering problem in which all packets belonging to the same application flow are routed through the same intermediate port and hence the same path through the switch. Unfortunately, this method of load-balancing can lead to instability, depending on the mix of flow sizes and durations in the group of flows that gets randomly assigned to route through the same intermediate port. In this paper, we show that the randomized load-balancing of application flows can be enhanced to provably guarantee both stability and packet ordering by extending the approach with safety mechanisms that can uniformly diffuse packets across the switch whenever there is a build-up of packets waiting to route through some intermediate port. Although simple and intuitive, our experimental results show that our extended randomized load-balancing approach outperforms existing load-balanced switch architectures.\",\n \"Title: Sharing a global on-chip transmission line medium without centralized scheduling\\nYear: 2016\\n\\nAbstract: We consider the design of a shared global on-chip communication medium using repeated equalized transmission lines (RETLs). Our design overcomes a number of limitations with previously proposed shared global mediums based on transmission lines. Prior solutions require wide-pitch transmission lines that occupy considerable area, do not support multicast or broadcast operations, and employ centralized schedulers that are difficult to scale. In this paper, we propose a novel design based on RETLs that utilizes thin transmission lines that require a much narrower pitch, about 6x narrower in comparison to previously proposed wide-pitch-based designs. In addition, our design supports multicast and broadcast operations, which are critical for the implementation of cache coherency protocols. Moreover, our design is based on fully distributed arbitration protocols that can achieve very high throughput and bandwidth utilization, but are simple to implement. We demonstrate a design using 32 lanes of 20 Gb/s differential RETLs that provides 640 Gb/s aggregated throughput and enables communications between any on-chip cores in under two core clock cycles, including multicast and broadcast communications. Given the narrow pitch of RETLs, our design can easily scale to multiple terabits per seconds with additional lanes. Simulation results with both synthetic and real benchmarks with up to 64 parallel threads demonstrate that our proposed distributed solutions are capable of achieving near ideal throughput.\",\n \"Title: A Single-Tier Virtual Queuing Memory Controller Architecture for Heterogeneous MPSoCs.\\nYear: 2017\\n\\nAbstract: Heterogeneous MPSoCs typically integrate diverse cores, including application CPUs, GPUs, and HD coders. These cores commonly share an off-chip memory to save cost and energy, but their memory accesses often interfere with each other, leading to undesirable consequences like a slowdown of application performance or a failure to sustain real-time performance. The memory controller plays a central role in meeting the QoS needs of real-time cores while maximizing CPU performance. Previous QoS-aware memory controllers are based on a classic two-tier queuing architecture that buffers memory transactions at the first tier, followed by a second tier that buffers translated DRAM commands. In these designs, QoS-aware policies are used to schedule competing transactions at the first stage, but the translated DRAM commands are served in FIFO order at the second stage. Unfortunately, once the scheduled transactions have been forwarded to the command stage, newly arriving transactions that may be more critical cannot be served ahead of those translated commands that are already queued at the second stage. To address this, we propose a scalable memory controller architecture based on single-tier virtual queuing (STVQ) that maintains a single tier of request queues and employs an efficacious scheduler that considers both QoS requirements and DRAM bank states. In comparison with previous QoS-aware memory controllers, the proposed STVQ memory controller reduces CPU slowdown by up to 13.9% while satisfying all frame rate requirements. We propose further optimizations that can significantly increase row-buffer hits by up to 66.2% and reduce memory latency by up to 19.8%.\",\n \"Title: Improving Backpressure-based Adaptive Routing via Incremental Expansion of Routing Choices.\\nYear: 2017\\n\\nAbstract: Backpressure-based adaptive routing algorithms have been studied extensively in the literature. Although backpressure-based adaptive routing algorithms have been shown to be network-wide throughput optimal, they typically have poor delay performance under light or moderate loads because packets may be sent over unnecessarily long routes. Further, backpressure-based algorithms have required every node to compute differential backlogs for every destination queue with the corresponding destination queue at every adjacent node. This computation is expensive given the large number of possible pairwise differential backlogs and requires many exchanges of backlog information between adjacent nodes. In this paper, we propose new backpressure-based adaptive routing algorithms that only use shortest-path routes to destinations when they are sufficient to accommodate the given traffic load, but the proposed algorithms will incrementally expand routing choices as needed to accommodate increasing traffic loads. We show analytically by means of fluid analysis that the proposed algorithms retain network-wide throughput optimality, and we show empirically by means of simulations that our proposed algorithms provide substantial improvements in delay performance. Our evaluations further show that in practice, our approach dramatically reduces the number of pairwise differential backlogs that have to be computed and the amount of corresponding backlog information that has to be exchanged because routing choices are only incrementally expanded as needed.\",\n \"Title: Harvesting Row-Buffer Hits via Orchestrated Last-Level Cache and DRAM Scheduling for Heterogeneous Multicore Systems\\nYear: 2018\\n\\nAbstract: In heterogeneous multicore systems, the memory subsystem, including the last-level cache and DRAM, is widely shared among the CPU, the GPU, and the real-time cores. Due to their distinct memory traffic patterns, heterogeneous cores result in more frequent cache misses at the last-level cache. As cache misses travel through the memory subsystem, two schedulers are involved for the last-level cache and DRAM, respectively. Prior studies treated the scheduling of the last-level cache and DRAM as independent stages. However, with no orchestration and limited visibility of memory traffic, neither scheduling stage is able to ensure optimal scheduling decisions for memory efficiency. Unnecessary precharges and row activations happen in DRAM when the memory scheduler is ignorant of incoming cache misses, and DRAM row-buffer states are invisible to the last-level cache. In this article, we propose a unified memory controller for the the last-level cache and DRAM with orchestrated schedulers. The memory scheduler harvests row-buffer hit opportunities in cache request buffers during spare time without inducing significant implementation cost. We further introduce a dynamic orchestrated scheduling policy to improve memory efficiency while achieving target CPU IPC. Extensive evaluations show that the proposed controller improves the total memory bandwidth of DRAM by 16.8% on average and saves DRAM energy by up to 29.7% while achieving comparable CPU IPCs. With the dynamic scheduling policy, the unified controller achieves the same IPC as the conventional design and increases DRAM bandwidth by 9.2%. In addition, we explore the potential of the proposed memory controller to attain improvements on both memory bandwidth and CPU IPC.\",\n \"Title: SARA: Self-Aware Resource Allocation for Heterogeneous MPSoCs.\\nYear: 2018\\n\\nAbstract: In modern heterogeneous MPSoCs, the management of shared memory resources is crucial in delivering end-to-end QoS. Previous frameworks have either focused on singular QoS targets or the allocation of partitionable resources among CPU applications at relatively slow timescales. However, heterogeneous MPSoCs typically require instant response from the memory system where most resources cannot be partitioned. Moreover, the health of different cores in a heterogeneous MPSoC is often measured by diverse performance objectives. In this work, we propose the Self-Aware Resource Allocation (SARA) framework for heterogeneous MPSoCs. Priority-based adaptation allows cores to use different target performance and self-monitor their own intrinsic health. In response, the system allocates non-partitionable resources based on priorities. The proposed framework meets a diverse range of QoS demands from heterogeneous cores.\",\n \"Title: Network optimization for unified packet and circuit switched networks\\nYear: 2018\\n\\nAbstract: Internet traffic continues to grow relentlessly, driven largely by increasingly high resolution video content. Although studies have shown that the majority of packets processed by Internet routers are pass-through traffic, they nonetheless have to be queued and routed at every hop in current networks, which unnecessarily adds substantial delays and processing costs. Such pass-through traffic can be better circuit-switched through the underlying optical transport network by means of pre-established circuits, which is possible in a unified packet and circuit switched network. In this paper, we propose a novel convex optimization framework based on a new destination-based multicommodity flow formulation for the allocation of circuits in such unified networks. In particular, we consider two deployment settings, one based on real-time traffic monitoring, and the other relying upon history-based traffic predictions. In both cases, we formulate global network optimization objectives as concave functions that capture the fair sharing of network capacity among competing traffic flows. The convexity of our problem formulations ensures globally optimal solutions.\",\n \"Title: Network DVR: a programmable framework for application-aware trace collection\\nYear: 2010\\n\\nAbstract: Network traces are essential for a wide range of network applications, including traffic analysis, network measurement, performance monitoring, and security analysis. Existing capture tools do not have sufficient built-in intelligence to understand these application requirements. Consequently, they are forced to collect all packet traces that might be useful at the finest granularity to meet a certain level of accuracy requirement. It is up to the network applications to process the per-flow traffic statistics and extract meaningful information. But for a number of applications, it is much more efficient to record packet sequences for flows that match some application-specific signatures, specified using for example regular expressions. A basic approach is to begin memory-copy (recording) when the first character of a regular expression is matched. However, often times, a matching eventually fails, thus consuming unnecessary memory resources during the interim. In this paper, we present a programmable application-aware triggered trace collection system called Network DVR that performs precisely the function of packet content recording based on user-specified trigger signatures. This in turn significantly reduces the number of memory copies that the system has to consume for valid trace collection, which has been shown previously as a key indicator of system performance [8]. We evaluated our Network DVR implementation on a practical application using 10 real datasets that were gathered from a large enterprise Internet gateway. In comparison to the basic approach in which the memory-copy starts immediately upon the first character match without triggered-recording, Network DVR was able to reduce the amount of memory-copies by a factor of over 500× on average across the 10 datasets and over 800× in the best case.\",\n \"Title: Efficient Traffic Load-Balancing via Incremental Expansion of Routing Choices.\\nYear: 2019\\n\\nAbstract: Routing policies play a major role in the performance of communication networks. Backpressure-based adaptive routing algorithms where traffic is load balanced along different routing paths on a per-packet basis have been studied extensively in the literature. Although backpressure-based algorithms have been shown to be networkwide throughput optimal, they typically have poor delay performance under light or moderate loads, because packets may be sent over unnecessarily long routes. Further, backpressure-based algorithms have required every node to compute differential backlogs for every per-destination queue with the corresponding per-destination queue at every adjacent node, which is expensive given the large number of possible pairwise differential backlogs between neighbor nodes. In this article, we propose new backpressure-based adaptive routing algorithms that only use shortest-path routes to destinations when they are sufficient to accommodate the given traffic load, but the proposed algorithms will incrementally expand routing choices as needed to accommodate increasing traffic loads. We show analytically by means of fluid analysis that the proposed algorithms retain networkwide throughput optimality, and we show empirically by means of simulations that our proposed algorithms provide substantial improvements in delay performance. Our evaluations further show that, in practice, our approach dramatically reduces the number of pairwise differential backlogs that have to be computed and the amount of corresponding backlog information that has to be exchanged, because routing choices are only incrementally expanded as needed.\",\n \"Title: Trained Biased Number Representation for ReRAM-Based Neural Network Accelerators\\nYear: 2019\\n\\nAbstract: Recent works have demonstrated the promise of using resistive random access memory (ReRAM) to perform neural network computations in memory. In particular, ReRAM-based crossbar structures can perform matrix-vector multiplication directly in the analog domain, but the resolutions of ReRAM cells and digital/analog converters limit the precisions of inputs and weights that can be directly supported. Although convolutional neural networks (CNNs) can be trained with low-precision weights and activations, previous quantization approaches are either not amenable to ReRAM-based crossbar implementations or have poor accuracies when applied to deep CNNs on complex datasets. In this article, we propose a new CNN training and implementation approach that implements weights using a trained biased number representation, which can achieve near full-precision model accuracy with as little as 2-bit weights and 2-bit activations on the CIFAR datasets. The proposed approach is compatible with a ReRAM-based crossbar implementation. We also propose an activation-side coalescing technique that combines the steps of batch normalization, non-linear activation, and quantization into a single stage that simply performs a clipped-rounding operation. Experiments demonstrate that our approach outperforms previous low-precision number representations for VGG-11, VGG-13, and VGG-19 models on both the CIFAR-10 and CIFAR-100 datasets.\",\n \"Title: A Self-aware Resource Management Framework for Heterogeneous Multicore SoCs with Diverse QoS Targets\\nYear: 2019\\n\\nAbstract: In modern heterogeneous MPSoCs, the management of shared memory resources is crucial in delivering end-to-end QoS. Previous frameworks have either focused on singular QoS targets or the allocation of partitionable resources among CPU applications at relatively slow timescales. However, heterogeneous MPSoCs typically require instant response from the memory system where most resources cannot be partitioned. Moreover, the health of different cores in a heterogeneous MPSoC is often measured by diverse performance objectives. In this work, we propose the Self-Aware Resource Allocation framework for heterogeneous MPSoCs. Priority-based adaptation allows cores to use different target performance and self-monitor their own intrinsic health. In response, the system allocates non-partitionable resources based on priorities. The proposed framework meets a diverse range of QoS demands from heterogeneous cores. Moreover, we present a runtime scheme to configure priority-based adaptation so that distinct sensitivities of heterogeneous QoS targets with respect to memory allocation can be accommodated. In addition, the priority of best-effort cores can also be regulated.\",\n \"Title: ROAD - Routability Analysis and Diagnosis Framework Based on SAT Techniques.\\nYear: 2019\\n\\nAbstract: Routability diagnosis has increasingly become the bottleneck in detailed routing for sub-10nm technology due to the limited tracks, high density, and complex design rules. The conventional ways to examine the routability of detailed routing are ILP- and SAT-based techniques. However, once we identify the routability, the diagnosis remains an open problem for physical designers. In this paper, we propose a novel framework, called ROAD, which diagnoses explicit reasons for routing failures. The proposed ROAD framework utilizes a diagnosis-friendly SAT formulation to represent design's layout and diagnoses the routability with SAT solving techniques. Based on the diagnosis, ROAD provides human-interpretable explanations for conflicted routing conditions. To show the practical value of our framework, we also generate comprehensive test-sets that enable exhaustive exploration of layouts based on Rent's rule. We demonstrate that ROAD successfully examines conflict causes for diverse pin layouts. Throughout extensive diagnosis, we also present several key findings for design failure. ROAD performs routability diagnosis within 2 minutes on average for 90 grids testsets, while diagnosing the exact causes of routing failures in terms of congestion and conditional design rules.\",\n \"Title: Uniform Minimal First: Latency Reduction in Throughput-Optimal Oblivious Routing for Mesh-Based Networks-on-Chip\\nYear: 2019\\n\\nAbstract: Mesh-based networks-on-chips (NoCs) are increasingly used for on-chip communications in embedded multicore processors. O1TURN is a well-known oblivious routing algorithm for mesh-based NoCs that has been shown to be worst-case throughput optimal for even network radices, but not for odd radices. More recently, another oblivious routing algorithm called U2TURN has been shown to be worst-case throughput optimal for both odd and even radices. This is accomplished by load-balancing among 2-turn paths in XYX or YXY routing, including nonminimal paths. Besides being worst-case throughput optimal, U2TURN achieves higher throughput than O1TURN under adversarial traffic. However, for random traffic, where the traffic is inherently load-balanced, O1TURN achieves lower network latency since it only considers minimal paths. In this letter, we propose a hybrid oblivious routing algorithm called uniform-minimal-first (UMF) routing. UMF works by exploiting any inherent load-balancing characteristics of the traffic pattern to reduce packet latency, but it retains the throughput optimality of U2TURN for both odd and even radices, and it achieves the performance of U2TURN under adversarial traffic. UMF is very inexpensive to implement as it just requires incrementing two small counters, but only for the head flit when a node injects a new packet (not for any pass-through traffic). These simple updates can be performed one cycle ahead of packet injection to avoid slowing down any router pipeline stage. Despite its simplicity, UMF outperforms U2TURN by 23.7% under random traffic and O1TURN by 12.6% under adversarial traffic.\",\n \"Title: Learning Accurate And Interpretable Decision Rule Sets From Neural Networks\\nYear: 2021\\n\\nAbstract: This paper proposes a new paradigm for learning a set of independent logical rules in disjunctive normal form as an interpretable model for classification. We consider the problem of learning an interpretable decision rule set as training a neural network in a specific, yet very simple two-layer architecture. Each neuron in the first layer directly maps to an interpretable if-then rule after training, and the output neuron in the second layer directly maps to a disjunction of the first-layer rules to form the decision rule set. Our representation of neurons in this first rules layer enables us to encode both the positive and the negative association of features in a decision rule. State-of-the-art neural net training approaches can be leveraged for learning highly accurate classification models. Moreover, we propose a sparsity-based regularization approach to balance between classification accuracy and the simplicity of the derived rules. Our experimental results show that our method can generate more accurate decision rule sets than other state-of-the-art rule-learning algorithms with better accuracy-simplicity trade-offs. Further, when compared with uninterpretable black-box machine learning approaches such as random forests and full-precision deep neural networks, our approach can easily find interpretable decision rule sets that have comparable predictive performance.\",\n \"Title: CoRe-ECO: Concurrent Refinement of Detailed Place-and-Route for an Efficient ECO Automation\\nYear: 2021\\n\\nAbstract: With the relentless scaling of technology nodes, physical design engineers encounter non-trivial challenges caused by rapidly increasing design complexity, particularly in the routing stage. Back-end designers must manually stitch/modify all of the design rule violations (DRVs) that remain after automatic place-and-route (P&R), during the implementation of engineering change orders (ECOs). In ...\",\n \"Title: Design and System Technology Co-Optimization Sensitivity Prediction for VLSI Technology Development using Machine Learning\\nYear: 2021\\n\\nAbstract: As technology nodes evolve, geometric pitch scaling starts to slow down. In order to retain the trend of the Moore's Law, Design Technology Co-Optimization (DTCO) and System Technology Co-Optimization (STCO) are introduced together to continue scaling beyond 5nm using pitch scaling, patterning, and novel 3D cell structures (i.e., Complementary-FET (CFET)). However, numerous DTCO and STCO iteration...\",\n \"Title: Knowledge-Augmented Methods for Natural Language Processing.\\nYear: 2022\\n\\nAbstract: Knowledge in natural language processing (NLP) has been a rising trend especially after the advent of large scale pre-trained models. NLP models with attention to knowledge can i) access unlimited amount of external information; ii) delegate the task of storing knowledge from its parameter space to knowledge sources; iii) obtain up-to-date information; iv) make prediction results more explainable via selected knowledge. In this tutorial, we will introduce the key steps in integrating knowledge into NLP, including knowledge grounding from text, knowledge representation and fusing. In addition, we will introduce recent state-of-the-art applications in fusing knowledge into language understanding, language generation and commonsense reasoning.\",\n \"Title: Monolithic 3D Semiconductor Footprint Scaling Exploration Based on VFET Standard Cell Layout Methodology, Design Flow, and EDA Platform\\nYear: 2022\\n\\nAbstract: Continued scaling in accordance with Moore's law is becoming increasingly difficult. Pitch shrinkage and standard cell height reduction via design technology co-optimization with design rules have sustained this scaling until recently. However, we observe that standard cell device scaling is becoming saturated due to yield and cost. One way to continue device footprint reduction is by expanding in the third dimension via monolithic 3D integration, using for example stacked gate-all-around (GAA) devices, complementary FETs, vertical FETs, and 3D logic. However, using these footprint scaling approaches to increase device density creates new problems. Using vertical gate-all-around FET (VFET) technologies as a specific instance of 3D device scaling, we demonstrate that the key bottleneck to footprint scaling is the pin density wall. The footprint of a block is predominantly limited by the pin density as we increase the number of active device layers. While a full-blown paradigm shift on layout methodology, design flow, and electronic design automation (EDA) platform is not available now, we describe in this article three specific baby steps that can alleviate the pin density problem and demonstrate their potential benefits for footprint scaling: (1) allocating standard cell pin sideways and using block-level routing with the local interconnect layers; (2) using the backside of the substrate for the power distribution network; and (3) using the generation of more complex standard cells. We show via several core designs that a 42.6% reduction in the core area is achievable when a combination of these operations is employed.\",\n \"Title: Machine Learning Prediction for Design and System Technology Co-Optimization Sensitivity Analysis\\nYear: 2022\\n\\nAbstract: As technology nodes continue to advance relentlessly, geometric pitch scaling starts to slow down. In order to retain the trend of Moore’s law, design technology co-optimization (DTCO) and system technology co-optimization (STCO) are introduced together to continue scaling beyond 5 nm using pitch scaling, patterning, and novel 3-D cell structures [i.e., complementary-FET (CFET)]. However, numerous DTCO and STCO iterations are needed to continue block-level area scaling with considerations of physical layout factors: 1) various standard cell (SDC) library sets (i.e., different cell heights and conventional FET); 2) design rules (DRs); 3) back end of line (BEOL) settings; and 4) power delivery network (PDN) configurations. The growing turnaround time (TAT) among SDC design, DR optimization, and block-level area evaluation becomes one of the major bottlenecks in DTCO and STCO explorations. In this work, we develop a machine learning model that combines bootstrap aggregation and gradient boosting techniques to predict the sensitivity of minimum valid block-level area of various physical layout factors. We first demonstrate that the proposed model achieves 16.3% less mean absolute error (MAE) than the previous work for testing sets. Then, we show that the proposed model successfully captures the block-level area sensitivity of new SDC library sets, new BEOL settings, and new PDN settings with 0.013, 0.004, and 0.027 MAE, respectively. Finally, compared to the previous work, the proposed approach improves the robustness of predicting new circuit designs by up to 6.76%. The proposed framework provides more than \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$100\\\\times $ </tex-math></inline-formula>\\n speedup compared to conventional DTCO and STCO exploration flows.\",\n \"Title: Spectrum Pursuit With Residual Descent for Column Subset Selection Problem: Theoretical Guarantees and Applications in Deep Learning\\nYear: 2022\\n\\nAbstract: We propose a novel technique for dataset summarization by selecting representatives from a large, unsupervised dataset. The approach is based on the concept of self-rank, defined as the minimum number of samples needed to express all dataset samples with an accuracy proportional to the rank-K approximation. As the exact computation of self-rank requires a computationally expensive combinatorial search, we propose an efficient algorithm that jointly estimates self-rank and selects the most informative samples in a linear order of complexity w.r.t the data size. We derive a new upper bound for the approximation ratio (AR), the ratio of obtained projection error using selected samples to the best rank-K approximation error. The best previously known AR for self-representative low-rank approximation was presented in ICML 2017, which was further improved by the bound root 1 + K reported in NeurIPS 2019. Both of these bounds are obtained by brute force search, which is not practical, and these bounds depend solely on K, the number of selected samples. In contrast, we describe an adaptive AR that takes into consideration the spectral properties and spikiness measure of the original dataset, A is an element of R-NxM. In particular, our performance bound is proportional to the condition number kappa(A). Our derived AR is expressed as 1 + (kappa(A)(2) - 1)/(N - K), which approaches 1 and is optimal in two extreme spectral distribution instances. In the worst case, AR is shown not to exceed 1.25 for the proposed method. Our proposed algorithm enjoys linear complexity w.r.t. size of original dataset, which results in filling a historical gap between practical and theoretical methods in finding representatives. In addition to evaluating the proposed algorithm on a synthetic dataset, we show that it can be utilized in real-world applications such as graph node sampling for optimizing the shortest path criterion, learning a classifier with representative data, and open-set identification.\",\n \"Title: LiteCON: An All-photonic Neuromorphic Accelerator for Energy-efficient Deep Learning\\nYear: 2022\\n\\nAbstract: Deep learning is highly pervasive in today's data-intensive era. In particular, convolutional neural networks (CNNs) are being widely adopted in a variety of fields for superior accuracy. However, computing deep CNNs on traditional CPUs and GPUs brings several performance and energy pitfalls. Several novel approaches based on ASIC, FPGA, and resistive-memory devices have been recently demonstrated with promising results. Most of them target only the inference (testing) phase of deep learning. There have been very limited attempts to design a full-fledged deep learning accelerator capable of both training and inference. It is due to the highly compute- and memory-intensive nature of the training phase. In this article, we propose LiteCON, a novel analog photonics CNN accelerator. LiteCON uses silicon microdisk-based convolution, memristor-based memory, and dense-wavelength-division-multiplexing for energy-efficient and ultrafast deep learning. We evaluate LiteCON using a commercial CAD framework (IPKISS) on deep learning benchmark models including LeNet and VGG-Net. Compared to the state of the art, LiteCON improves the CNN throughput, energy efficiency, and computational efficiency by up to 32×, 37×, and 5×, respectively, with trivial accuracy degradation.\",\n \"Title: JARVA: Joint Application-Aware Oblivious Routing and Static Virtual Channel Allocation\\nYear: 2022\\n\\nAbstract: This article proposes a joint application-aware oblivious routing and static virtual channel allocation framework to enable better deadlock-free performance in on-chip interconnection networks.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":127,"string":"127"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":261,"string":"261"}}},{"rowIdx":262,"cells":{"question_id":{"kind":"string","value":"Lingjia Liu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Angle-Based Downlink Beam Selection and User Scheduling for Massive MIMO Systems\" using the following items: 1. Next-generation cellular system\n2. Millimeter-wave frequencies\n3. Beam management\n4. Angle-based downlink precoding \n5. Superiority over conventional techniques"},"answer":{"kind":"string","value":"The next-generation cellular system operating in millimeter-wave (mm-Wave) frequencies requires different signal processing schemes from the legacy LTE system. Among these, beam management aligns the transmitter-receiver pairs with narrow beams and serves as an essential initial acquisition procedure. This paper introduces a novel angle-based downlink precoding strategy, including beam selection and user scheduling for a full dimension (FD) MIMO-OFDM system. The highly directional mm-Wave channel allows the system to perform user/beam scheduling rather than pure user scheduling during the precoding process. A beam-based receive matrix eliminates the remaining intra-cell interference caused by overlapped beams. The performance analysis proves the superiority of the proposed precoding and scheduling strategies over the conventional technique."},"correct_answer":{"kind":"string","value":"The next-generation cellular system operating in millimeter-wave (mm-Wave) frequencies requires different signal processing schemes from the legacy LTE system. Among these, beam management aligns the transmitter-receiver pairs with narrow beams and serves as an essential initial acquisition procedure. This paper introduces a novel angle-based downlink precoding strategy, including beam selection and user scheduling for a full dimension (FD) MIMO-OFDM system. The highly directional mm-Wave channel allows the system to perform user/beam scheduling rather than pure user scheduling during the precoding process. A beam-based receive matrix eliminates the remaining intra-cell interference caused by overlapped beams. The performance analysis proves the superiority of the proposed precoding and scheduling strategies over the conventional technique."},"documents":{"kind":"list like","value":["Title: On Coding Over Finite \"Packets\" In Wireless Communication Systems\nYear: 2013\n\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In light of this challenge, this paper investigates the throughput performance of a wireless communication system under channel coding over finite \"packets.\" When we apply coding over multiple \"packets,\" the underlying wireless channel can be effectively modeled as a finite-state Markov process. By linking the characteristics of the underlying physical channel to the parameters of the Markov process, we are able to derive the channel dispersion of the corresponding system. The channel dispersion is then used to assess the coding performance of various communication strategies. It is interesting to find that when there is a constraint on the total blocklength, coding over large \"packets\" will give better performance than that of coding over small \"packets.\"","Title: Downlink MIMO in LTE-advanced: SU-MIMO vs. MU-MIMO.\nYear: 2012\n\nAbstract: Single-user multi-antenna technologies are well upported in current standard specifications like LTE Release 8/9. Further development of the specification (LTE-Advanced) is expected to conform to the requirements for IMT-Advanced systems. One of the key enabling features of LTE-Advanced to meet IMT-Advanced downlink performance requirements is multi-user MIMO, where a transmitter serves multiple u...","Title: Adaptive scheduling for multicasting hard deadline constrained prioritized data via network coding.\nYear: 2012\n\nAbstract: Network coding offers a promising platform for multicast transmission by approaching its min-cut capacity. However, pushing the network throughput toward this upper bound comes with a sacrifice in delivery delay due to the decoding procedure that requires performing batch of coded packets. Further, in some transmission scenarios where the receivers experience deep fading or unable to collect a full set of the transmitted data, no useful information is recovered. The effect is more severe in the networks where the transmitted information has priority structure with hard deadline constraint due to the limited delivery time and data interdependencies. In this paper, we consider single-hop wireless networks where the transmitter wishes to multicast hard deadline constrained prioritized data to many receivers over lossy channels. We first study the network performance of a variety of transmission techniques, depending on how the transmitter schedules transmission in each time slot. We then propose an adaptive encoding and scheduling technique to maximize the network throughput. To find the optimal transmission scheduling at the presence of the network dynamics, we cast the problem in the framework of Markov Decision Processes (MDP) and use backward induction method to find an optimal solution. We further propose simulation-based algorithm and greedy scheduling technique that obtain high performance with much lower time complexity. Both analytical and simulation results have been provided to corroborate the effectiveness of the proposed techniques.","Title: Distributed optimal power control for multicarrier cognitive systems\nYear: 2012\n\nAbstract: In this paper, the power optimization of the multicarrier cognitive system underlying the primary network is investigated. We consider the interference coupled cognitive network under individual secondary user's power constraint and primary user's rate constraint. A multicarrier discrete distributed (MCDD) algorithm based on Gibbs sampler is proposed. Although the problem is nonconcave, MCDD is proved to converge to the global optimal solution. To reduce the computational complexity and convergence time, the Gibbs sampler based Lagrangian algorithm (GSLA) is proposed to get a near optimal solution. We also provide simulation results to show the effectiveness of the proposed algorithms.","Title: Resource Allocation and Quality of Service Evaluation for Wireless Communication Systems Using Fluid Models\nYear: 2007\n\nAbstract: Wireless systems offer a unique mixture of connectivity, flexibility, and freedom. It is therefore not surprising that wireless technology is being embraced with increasing vigor. For real-time applications, user satisfaction is closely linked to quantities such as queue length, packet loss probability, and delay. System performance is therefore related to, not only Shannon capacity, but also quality of service (QoS) requirements. This work studies the problem of resource allocation in the context of stringent QoS constraints. The joint impact of spectral bandwidth, power, and code rate is considered. Analytical expressions for the probability of buffer overflow, its associated exponential decay rate, and the effective capacity are obtained. Fundamental performance limits for Markov wireless channel models are identified. It is found that, even with an unlimited power and spectral bandwidth budget, only a finite arrival rate can be supported for a QoS constraint defined in terms of exponential decay rate","Title: Adaptive resource allocation for heterogeneous traffic over heterogeneous relay networks\nYear: 2013\n\nAbstract: Future wireless communication networks will face the dual challenge of supporting large traffic volumes while providing reliable service for heterogeneous traffic types. In order to meet the ever increasing traffic demand, heterogeneous relay network is introduced as an enabling technology for the fourth generation (4G) mobile broadband networks. In this paper, we will investigate optimal power and subcarrier allocation strategies for heterogeneous relay networks under statistical quality of service (QoS) constraints. To be specific, we will characterize the effective capacity of a wireless relay system under QoS constraints. The properties of the optimal resource and subcarrier allocation strategies for delay-sensitive traffic over heterogeneous relay networks will also be identified. Two low complexity resource and subcarrier allocation algorithms will be introduced to optimize the effective capacity. Our results suggest that the optimal power and subcarrier allocation strategies depend heavily on the underlying QoS constraint. In the low signal-to-interference-plus-noise (SINR) regime, when there is no QoS constraint, both base stations and relay nodes will allocate all the transmit power to the best subcarrier. However, as the QoS requirement becomes more stringent, both base stations and relay nodes will spread their transmit power over multiple subcarriers.","Title: Quality of Service Analysis for Wireless User-Cooperation Networks\nYear: 2007\n\nAbstract: A wireless communication system in which multiple users cooperate to transmit information to a common destination is considered. The traffic generated by the users is subject to a stringent quality of service requirement, which is defined in terms of the asymptotic decay-rate of buffer occupancy. The performance of this communication system is analyzed, and the corresponding achievable rate-region for the two-user scenario is identified. A simple user-cooperation scheme that improves performance is proposed. This cooperative scheme is shown to significantly enlarge the achievable rate-region of the service constrained communication system, provided that the quality of the wireless link between cooperating users is better than the individual connections from the users to the intended destination. Numerical results further indicate that the gains of cooperative strategies can be substantial. This suggests that cooperation allows for a fair distribution of the wireless resources among active users.","Title: User Cooperation in the Absence of Phase Information at the Transmitters\nYear: 2008\n\nAbstract: In this paper, a multiuser communication system in which wireless users cooperate to transmit information to a base station is considered. The proposed scheme can significantly enlarge the achievable rate region, provided that the wireless connections between pairs of cooperating users are stronger than the connection from every user to the base station. The gains in transmission rate remain substantial even when the channel phase information is only available at the receivers, not at the transmitters. In the proposed scheme, a transmission period is divided into two time intervals. During the first time interval, wireless users send data to the base station and to the neighboring users simultaneously using a broadcast channel paradigm. During the second time interval, the users cooperate to transmit information to the base station. The achievable rate region corresponding to this paradigm is characterized under a random phase channel model for a two-user system. Results are then generalized to a multiple-user scenario. For fixed system parameters, the achievable rate region is strictly larger than that of the traditional multiple-access channel, thereby allowing a fair distribution of the wireless resources among users. Numerical analysis suggests that cooperating with a single partner is enough to achieve most of the benefits associated with cooperation.","Title: Cooperative Communication Technologies For Lte-Advanced\nYear: 2010\n\nAbstract: The LTE-Advanced (LTE-A) system is currently under development to allow for significantly higher spectral efficiency and data throughput than LTE systems. In a wireless system based on orthogonal frequency division multiplexing (OFDM) with frequency reuse factor one such as LTE, the achievable cell spectral efficiency is often limited by the inter-cell interference or coverage shortage of base stations. Hence in LTEA, coordinated multi-point (CoMP) transmission/reception (a.k.a. multi-cell MIMO or base station cooperation) and relaying technologies are being introduced to clear these major performance hurdles. In this paper, overall picture of cooperative communication technologies being discussed in LTE-A systems including CoMP and relayingis presented, together with considerations on system design.","Title: Link adaptation for energy-efficient uplink coordinated multi-point receptions.\nYear: 2011\n\nAbstract: We investigate link adaptation methods for energy-efficient uplink coordinated multi-point receptions. A system model for practical cellular networks is introduced, in which only a subset of base stations participates in cooperative link adaptation and cooperative decoding for uplink transmissions. To cope with channel-state-information (CSI) mismatch incurred from the system model, link adaptation controllers implementing rate back-off from the maximum achievable rate calculated with the mismatched CSI is introduced. From analytical and simulation results, it is concluded that under a certain condition, the rate back-off does not help to improve energy efficiency, where, for example, the condition holds when the CSI errors are modeled as additive Gaussian random variables. Furthermore, energy efficiency of multi-user spatial-division-multiple-access uplink transmissions is studied in isolated cooperative cellular networks. In this scenario, an analytical expression for the optimal link adaptation achieving maximum energy efficiency is obtained.","Title: Distributed heterogeneous traffic delivery over heterogeneous wireless networks\nYear: 2012\n\nAbstract: In order to meet the spectacular growth in mobile data traffic, one of the technologies is heterogeneous network, where small cells overlaid by large cells can be deployed. With such, base stations (BSs) can be of heterogeneous characteristics in bandwidth, capacity, load, backhaul delay, etc. Meanwhile, the traffic of diverse applications of a mobile station (MS) can be of heterogeneous quality of service (QoS) in rate, delay, etc. This paper proposes a framework to solve the problem of how to efficiently deliver heterogeneous traffic with heterogeneous QoS requirements in heterogeneous networks. We formulate optimization problems, to associate traffic flows with different QoS requirements of an MS to multiple BSs, so that QoS requirements can be satisfied, where the BS backhaul conditions are taken into account. Algorithms are proposed based on analysis. Numerical results show our framework can provide more efficiency in delay stringent and delay astringent traffic delivery.","Title: New leakage-based iterative coordinated beam-forming for multi-user MIMO in LTE-Advanced\nYear: 2012\n\nAbstract: In this paper, we investigate a typical LTE-Advanced multi-user MIMO system where mobile stations (MSs) feedback limited channel state information using codebook based approaches. A joint optimization of multi-user scheduling, linear transmit beam-forming, and receive combining is conducted at the base station to combat the intra-cell interference created by multi-user MIMO operation. Low complexity coordinated beam-forming schemes based on proportional-fair metric is proposed for jointly designing the beam-forming and receive combining vectors. Feedback schemes complied with LTE-Advanced specification is also introduced for the proposed coordinated beam-forming scheme. System level evaluation is conducted to show that the proposed coordinated beam-forming can help improving the performance of LTE-Advanced systems significantly.","Title: Automated Residential Demand Response: Algorithmic Implications of Pricing Models\nYear: 2012\n\nAbstract: Smart energy management is an important problem in Smart Grid network, and demand response (DR) is one of the key enabling technologies. If each home uses automated demand response which would opportunistically schedule devices that are flexible to run at any time in a large time window, towards the slots with lower electricity prices, peaks at these slots may happen. We denote such peaks as rebound peaks. We address the potential rebound peak problems of automated DR algorithms, and provide possible solutions. We illustrate why a rebound peak is possible via the insights we obtain from the optimal automated DR algorithm. We show that if the utility electricity supply cost is assumed to be a homogeneous function in the energy consumption over a certain time span, a system of multiple homes and utility company has the lowest total electricity supply cost if the electricity consumption from all the homes is flat over the time span. We study multiple approaches to reduce the rebound peak, and accordingly propose algorithms for DR at each home. Effectiveness of the approaches is verified by numerical results.","Title: Optimal fusion scheme in wireless sensor networks under sum-rate capacity constraint\nYear: 2010\n\nAbstract: In this paper, we investigate optimal fusion schemes for decentralized detection problems in which a network of wireless sensors provides relevant information about the state of nature to a fusion center. Upon independent reception of the signal, each sensor performs distributed binary detection and sends the decision as well as the reliability of the decision to the fusion center. The capacity region of the corresponding multi-access channel (MAC) from wireless sensors to the fusion center is identified and the sum-rate capacity is characterized. Further-more, it can be shown that when the number of wireless sensors is big enough, the sum-rate capacity of the corresponding MAC channel converges to a constant due to ¿channel-hardening¿. Based on this result, we analyze the performance of quantizing the reliability of the decentralized decision under the sum-rate capacity constraint. The corresponding optimal fusion scheme is derived and the analysis is conducted under the low signal-to-noise (SINR) regime to better reflect the reality.","Title: Capacity Of Multicarrier Multilayer Broadcast And Unicast Hybrid Cellular System With Independent Channel Coding Over Subcarriers\nYear: 2011\n\nAbstract: In this paper, we discuss the hybrid capacity region of a generic multicarrier multilayer broadcast and unicast cellular system with independent channel coding over subcarriers. In particular, we analytically derive the capacity region and provide conditions to achieve its boundary. The simulation results show that the hybrid capacity regions are considerably higher than those of the traditional time division multiplexing scheme.","Title: Spectrum Optimization For Ofdma Based Hybrid Wireless Networks\nYear: 2011\n\nAbstract: This paper proposes a new cooperative resource allocation scheme for OFDMA based hybrid network. Different from the traditional cognitive radio networks that aim to utilize the spectrum holes in an uncoordinated way, we study the joint resource allocation for both the primary users and the secondary users. Results show that our approach can achieve higher spectral efficiency and provide satisfactory admission control and QoS for all users.","Title: A New Cooperative Spectrum Sensing Scheme for Cognitive Ad-Hoc Networks.\nYear: 2011\n\nAbstract: As the radio spectrum is becoming more and more crowded, cognitive radio has recently become a hot research topic to improve the spectrum utilization efficiency. It is well known that the success of cognitive radio depends heavily on fast and efficient spectrum sensing that is very difficult in practice. Toward this end, this paper introduces a new guard-resident cooperative spectrum sensing scheme for a cognitive ad-hoc network. In particular, we classify cognitive nodes as either or based on the spectrum neighbor decision and distributed boundary search. The guard nodes sense the spectrum and then inform the resident nodes that are greatly relieved from spectrum sensing about the radio environmental changes. The analysis and simulation results show that the proposed algorithm can significantly reduce the total spectrum sensing load without sacrificing the sensing accuracy.","Title: Low complexity direction of arrival (DoA) estimation for 2D massive MIMO systems\nYear: 2012\n\nAbstract: Mobile data traffic is expected to almost double every year from 2012 to 2016. In order to address the challenge, “massive MIMO” has been proposed as one of the enabling technologies to significantly increase the spectral-efficiency of a wireless system. In “massive MIMO” systems, a base station will rely on the uplink sounding signals from mobile stations to figure out the channel knowledge to perform MIMO beam-forming. Accordingly, direction-of-arrival estimation at the base station becomes crucial for “massive MIMO” systems to realize the predicted capacity gains. In this paper, we study DoA estimation for two-dimensional (2D) “massive MIMO” systems in mobile wireless systems. To be specific, we derive the Cramer-Rao lower bound for 2D “massive MIMO” systems and introduce a low complexity direction-of-arrival estimation algorithm to jointly estimate elevation and azimuth angles of the arrived signals based on unitary transformation. Results suggest that the dimension of the antenna array at the base station plays an important role in the estimation performance. It is also found that azimuth estimation is more vulnerable compared to elevation estimation. These insights will be useful for designing practical “massive MIMO” systems in future mobile wireless communications.","Title: Cooperative Routing for Wireless Networks using Mutual-Information Accumulation\nYear: 2009\n\nAbstract: Cooperation between the nodes of wireless multihop networks can increase\ncommunication reliability, reduce energy consumption, and decrease latency. The\npossible improvements are even greater when nodes perform mutual information\naccumulation using rateless codes. In this paper, we investigate routing\nproblems in such networks. Given a network, a source, and a destination, our\nobjective is to minimize end-to-end transmission delay under energy and\nbandwidth constraints. We provide an algorithm that determines which nodes\nshould participate in forwarding the message and what resources (time, energy,\nbandwidth) should be allocated to each.\n Our approach factors into two sub-problems, each of which can be solved\nefficiently. For any transmission order we show that solving for the optimum\nresource allocation can be formulated as a linear programming problem. We then\nshow that the transmission order can be improved systematically by swapping\nnodes based on the solution of the linear program. Solving a sequence of linear\nprograms leads to a locally optimal solution in a very efficient manner. In\ncomparison to the proposed cooperative routing solution, it is observed that\nconventional shortest path multihop routing typically incurs additional delays\nand energy expenditures on the order of 70%.\n Our first algorithm is centralized, assuming that routing computations can be\ndone at a central processor with full access to channel state information for\nthe entire system. We also design two distributed routing algorithms that\nrequire only local channel state information. We provide simulations showing\nthat for the same networks the distributed algorithms find routes that are only\nabout two to five percent less efficient than the centralized algorithm.","Title: Secure network-coded wireless multicast for delay-sensitive data\nYear: 2012\n\nAbstract: Wireless multicast for delay-sensitive data is challenging because different receivers may experience different packet losses. Network coding offers significant advantages over the traditional Automatic Repeat-reQuest (ARQ) protocols in that it mitigates the need for retransmission and has the potential to approach the min-cut capacity. Network-coded multicast would be, however, vulnerable to false packet injection attacks, in which the adversary injects bogus packets to prevent receivers from correctly decoding the original data. Without a right defense in place, even a single bogus packet can completely change the decoding outcome. Existing solutions either incur high computation cost or cannot withstand high packet loss. In this paper, we propose a novel scheme to defend against false packet injection attacks on network-coded multicast for delay-sensitive data. Specifically, we propose an efficient authentication mechanism based on null space properties of coded packets, aiming to enable receivers to detect any bogus packets with high probability. We further design an adaptive scheduling algorithm based on Markov Decision Processes (MDP) to maximize the number of authenticated packets that can be received within a given time constraint. Both analytical and simulation results have been provided to demonstrate the efficacy and efficiency of our proposed scheme.","Title: Proportional fair scheduling for multi-cell multi-user MIMO systems\nYear: 2010\n\nAbstract: In this paper, a multi-cell multi-user MIMO scheme with advanced user pairing and scheduling algorithm is proposed to effectively explore multi-user diversity and to combat both intra-cell and inter-cell interference in the downlink of wireless communication systems. The optimality of the proposed user paring and scheduling algorithm is shown under generalized proportional fair metrics. System-level simulations are conducted to verify the performance of the proposed scheme with the agreed LTE-Advanced (LTE-A) system parameters. The results suggest the proposed scheme is a promising candidate for improving both the cell-edge user throughput and average cell throughput, and furthermore for fulfilling the IMT-Advanced (IMT-A) requirements.","Title: Performance analysis of wireless hybrid-ARQ systems with delay-sensitive traffic\nYear: 2010\n\nAbstract: The design of wireless communication schemes tailored to real-time traffic requires an analysis framework that goes beyond the traditional criterion of data throughput. This work considers an approach that relates physical system parameters to the queueing performance of wireless links. The potential benefits of multi-rate techniques such as hybrid-ARQ are assessed in the context of delay-sensitive traffic using large deviations. A continuous-time Markov channel model is employed to partition the instantaneous data-rate received at the destination into a finite number of states, each representing a mode of operation of the hybrid-ARQ scheme. The proposed methodology accounts for the correlation of the wireless channel across time, which is computed in terms of level-crossing rates. The tail asymptote governing buffer overflow probabilities at the transmitter is then used to provide a measure of overall performance. This approach leads to a characterization of the effective capacity of the system which, in turn, is applied to quantify the performance advantages of hybrid-ARQ over traditional schemes.","Title: Secure Wireless Multicast for Delay-Sensitive Data via Network Coding\nYear: 2013\n\nAbstract: Wireless multicast for delay-sensitive data is challenging because of the heterogeneity effect where each receiver may experience different packet losses. Fortunately, network coding, a new advanced routing protocol, offers significant advantages over the traditional Automatic Repeat reQuest (ARQ) protocols in that it mitigates the need for retransmission and has the potential to approach the min-cut capacity. Network-coded multicast would be, however, vulnerable to false packet injection attacks, in which the adversary injects bogus packets to prevent receivers from correctly decoding the original data. Without a right defense in place, even a single bogus packet can completely change the decoding outcome. Existing solutions either incur high computation cost or cannot withstand high packet loss. In this paper, we propose a novel scheme to defend against false packet injection attacks on network-coded multicast for delay-sensitive data. Specifically, we propose an efficient authentication mechanism based on null space properties of coded packets, aiming to enable receivers to detect any bogus packets with high probability. We further design an adaptive scheduling algorithm based on the Markov Decision Processes (MDP) to maximize the number of authenticated packets received within a given time constraint. Both analytical and simulation results have been provided to demonstrate the efficacy and efficiency of our proposed scheme.","Title: Routing In Cooperative Wireless Networks With Mutual-Information Accumulation\nYear: 2008\n\nAbstract: Cooperation between the nodes of wireless multi-hop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual-information accumulation, e.g., by using rateless codes. In this paper, we investigate routing problems in such networks. Given a network, a source and a destination, our objective is to minimize end-to-end transmission delay under a sum energy constraint. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any node decoding order we show that solving for the optimum resource allocation can be formulated as a linear problem. We then show that the decoding order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear program leads to a locally optimum solution in a very efficient manner. In comparison to the cooperative routings, it is observed that conventional shortest-path multihop routings incur additional delays and energy expenditures on the order of 70%. Since this initial solution is centralized, requiring full channel state information, we exploit the insights to design two distributed routing algorithms that require only local channel state information. We provide simulations showing that in the same networks the distributed algorithms find routes that are only about 2 - 5% less efficient than the centralized solution.","Title: Energy-efficient power allocation for delay-sensitive traffic over wireless systems\nYear: 2012\n\nAbstract: Energy-efficient communication becomes increasingly important for wireless communication systems partially due to the fact that the improvement in battery technology is much slower than the increase for processing power and energy consumption of electronic devices. On the other hand, the telecommunication industry predicts that the mobile data traffic will double almost every year for the next five years with more than two thirds of the future traffic being video. Since many of the video applications are delay-sensitive, it is extremely important to consider energy-efficient design for delay-sensitive traffics over wireless systems. This paper addresses resource allocation for maximizing the energy-efficiency of a wireless link under statistical quality of service (QoS) constraints. In the energy-efficiency analysis, both circuit power and transmission power of a communication system are taken into account. The joint impact of statistical QoS constraints, transmission power, and spectral bandwidth are considered. The unique globally optimal power allocation scheme is characterized. The intuition of the optimal strategy is obtained by looking at both low signal-to-noise ratio (SNR) regime and high SNR regime.","Title: Energy-efficient scheduling for downlink multi-user MIMO\nYear: 2012\n\nAbstract: Multi-user MIMO is the enabling technology for LTE-Advanced systems to meet IMT-Advanced targets. The gain of multi-user MIMO is achieved partially through advanced user-grouping, user-scheduling, and precoding. Traditionally, multiuser MIMO scheduling focuses solely on spectral-efficiency [1]. That is, the scheduler will strike to balance the cell-edge user spectral-efficiency as well as the cell-average spectral-efficiency. Similar to spectral-efficiency, energy-efficiency is becoming increasingly important for wireless communications. The energy efficiency is measured by a classical measure, “throughput per Joule”, while both RF transmit power and device electronic circuit power consumptions are considered. In this paper, an energy-efficient proportional-fair scheduling is proposed for downlink multi-user MIMO systems. To specific, the scheduling algorithm is proposed to balance cell-edge energy-efficiency and the cell-average energy-efficiency. The energy-efficient proportional-fair metric is defined and the optimal power allocation maximizing the performance measure is identified. System level evaluation suggests that multi-user MIMO could improve the energy-efficiency of a wireless communication system significantly.","Title: Doa Estimation And Capacity Analysis For 2d Active Massive Mimo Systems\nYear: 2013\n\nAbstract: Mobile data traffic is expected to have an exponential growth in the future. In order to meet the challenge as well as the form factor limitation on the base station, twodimensional (2D) \" massive MIMO\" has been proposed as one of the enabling technologies for future wireless systems. In 2D \" massive MIMO\" systems, a base station will rely on the uplink sounding signals to figure out the downlink spatial channel information to perform MIMO precoding. Accordingly, directionof- arrival (DoA) estimation of the underlying three-dimensional (3D) channel at the base station becomes essential for 2D \" massive MIMO\" systems to realize the predicted capacity gains.In this paper, we will analyze the performance of DoA estimation based on ESPRIT methods and study its impact on the capacity of 2D \" massive MIMO\" systems. To be specific, for ESPRIT-type algorithms, we will derive the closed-form expressions for the mean square errors of the elevation and azimuth angle estimations. These results will be used to obtain design intuitions for 2D antenna arrays at the base station as well as the capacity of the underlying 2D \" massive MIMO\" systems.","Title: Energy Efficiency of Hybrid Cellular With Heterogeneous QoS Provisions\nYear: 2014\n\nAbstract: In this letter, we consider a hybrid broadcast and unicast cellular network (hybrid cellular for short) with heterogeneous quality of service (QoS) constraints in the low-power regime. In particular, we consider the unicast user with delay constraint and the broadcast user with outage constraint. The transmission energy efficiency of the dirty paper coding (DPC) and time division multiple access (TDMA) schemes are analyzed and compared from information theoretic point of view. Specifically, the minimum energy per bit and the wideband slope region are derived in closed forms. While both DPC and TDMA schemes require the same minimum energy per bit, DPC outperforms TDMA with regard to the wideband slope region. We also obtain the critical points for both schemes beyond which the wideband slope decreases for both unicast and broadcast users. Finally, we show how the heterogeneous QoS constraints affect the energy efficiency in hybrid cellular.","Title: Resource Allocation for OFDM Cognitive Radio With Enhanced Primary Transmission Protection\nYear: 2014\n\nAbstract: Reducing interference to primary users and achieving good throughput are key objectives for secondary users in a cognitive radio (CR) network. In this letter, a rate loss constraint is considered in the sensing based spectrum sharing system of an OFDM CR network. Optimal resource allocation strategies including both sensing time and power allocation schemes are investigated to maximize the ergodic throughput of a secondary user under the rate loss constraints for primary users. A low complexity algorithm is introduced to characterize the optimal power allocation based on the sensing outcome at the SU. The effectiveness of the proposed resource allocation algorithms are demonstrated through simulation.","Title: Energy-Efficient Power Allocation for Delay-Sensitive Multimedia Traffic Over Wireless Systems\nYear: 2014\n\nAbstract: With the extremely high penetration rate of wireless broadband devices, the telecommunication industry predicts that the mobile data traffic will double almost every year for the next five years with more than two-thirds of the future traffic being mobile video. This trend clearly indicates that future mobile broadband networks will face the dual challenge of supporting large data volumes while providing reliable service for delay-sensitive mobile multimedia streams. This explosive demand for mobile multimedia communications has significantly increased not only spectrum requirements but also energy consumption. Energy-efficient communication is becoming a prime concern for mobile multimedia communications partially due to the fact that improvements in battery technology occur on a much slower scale than gains in processing power and energy consumption of electronic devices. Furthermore, the ever-increasing demand for wireless services and ubiquitous network access comes at the expense of a growing carbon footprint for the mobile wireless communication industry. This paper addresses resource allocation to maximize the energy efficiency of a wireless link under statistical quality-of-service (QoS) constraints for mobile multimedia traffic. In the energy-efficiency analysis, both circuit and transmit power values of mobile devices are taken into account. The joint impact of statistical QoS constraints, underlying circuit power consumption, transmission power, and spectral bandwidth is considered. The unique globally optimal power allocation scheme for delay-sensitive multimedia traffic is characterized. Intuition about optimal strategies is obtained by looking at both the low-signal-to-noise-ratio (SNR) regime and the high-SNR regime.","Title: Cooperative Communications For Lte-Advanced-Relay And Comp\nYear: 2014\n\nAbstract: The Long Term Evolution-Advanced (LTE-A) system is currently under development to allow for significantly higher spectral efficiency and data throughput than the LTE systems. In a wireless system based on orthogonal frequency division multiplexing with frequency reuse factor one, the achievable cell spectral efficiency is often limited by the inter-cell interference or coverage shortage of base stations. In LTE-A, coordinated multi-point transmission/reception (a.k.a. multi-cellMIMO or base station cooperation) and relaying technologies are being introduced to clear these major performance hurdles. In this paper, cooperative communication technologies being discussed in LTE-A systems are presented, together with considerations on system design. Copyright (C) 2012 John Wiley & Sons, Ltd.","Title: Cooperative transmission for cognitive radio networks using mutual-information accumulation\nYear: 2014\n\nAbstract: In cognitive radio networks, secondary users (SUs) have to control their transmission power so that the interference to primary users' (PUs) are tolerable. Under this situation, SUs will transmit at a relatively low power level experiencing high bit error rate with limited coverage range. To address this problem, cooperative transmission using mutual information accumulation is introduced to cognitive radio networks. To be specific, resource allocation problem in such a network is investigated and is factored into two sub-problems, each of which can be solved efficiently. The simulation results show that mutual information accumulation can significantly decrease the delay of a cognitive radio network especially in the scenario where the PU has a tight interference power constraint.","Title: Optimal resource allocation for sensing based spectrum sharing cognitive radio networks\nYear: 2014\n\nAbstract: To improve the spectral efficiency of a cognitive radio system, sensing based spectrum sharing (SBSS) technique combines the advantages of spectrum overlay and spectrum underlay. In this paper, we study the performance of SBSS under primary users' (PUs') rate loss constraint. To be specific, efficient algorithms are introduced to find the optimal sensing time and power allocation in both single-carrier and multi-carrier systems. Performance evaluation is conducted to compare the system throughput between SBSS and spectrum overlay techniques. Simulation results suggest that SBSS outperforms spectrum overlay when the transmitter of the secondary user (SUT) is far away from the receiver of the primary user (PUR) in the single-carrier case. In the multi-carrier case, SBSS can achieve 15.2% increase of spectral efficiency over spectrum overlay when all the channel gains are independent and identically distributed.","Title: Joint angle and delay estimation for 2D active broadband MIMO-OFDM systems.\nYear: 2013\n\nAbstract: Mobile data traffic is expected to have an exponential growth in the future. In order to meet the challenge as well as the form factor limitation at the base station, 2D \"Massive MIMO\", combined with OFDM, has been proposed as one of the enabling technologies to significantly increase the spectral efficiency of a broadband wireless system. In 2D broadband MIMO-OFDM systems, a base station will rely on the spatial information extracted from uplink sounding reference signals to perform downlink MIMO beam-forming. Accordingly, multi-dimensional parameter estimation of a ray-based multipath wireless channel becomes crucial for such systems to realize the predicted capacity gains. In this paper, we study joint angle and delay estimation for 2D broadband MIMO-OFDM systems and analytically assess its estimation performance. To be specific, a tensor-based standard ESPRIT algorithm is naturally applied to estimate the corresponding 3D channel parameters. Further, we give out the closed-form mean square error expressions for DoA estimation. It is found that the dimensionality of the antenna array at the base station, as well as the implementation of OFDM, play an important role in determining the estimation performance. Simulation is conducted to evaluate the performance of the tensor-based ESPRIT algorithm, and the empirical results match very well with that from the derived analytical expressions. These insights will be useful for designing practical 2D broadband MIMO-OFDM systems in future mobile wireless communications.","Title: Channel coding over finite transport blocks in modern wireless systems.\nYear: 2013\n\nAbstract: In modern wireless systems such as 3GPP LTE/LTE-Advanced, packets are partitioned into multiple transport blocks where each transport block is a group of resource elements with a common modulation and coding scheme. Accordingly, a transport block is the data unit in the physical layer of modern wireless systems. In this paper, we investigate the throughput performance of modern wireless systems under channel coding over finite transport blocks. When we apply coding over multiple transport blocks, the underlying wireless channel can be effectively modeled as a finite-state discrete-time Markov chain. We link the characteristics of the underlying physical channel to the parameters of the Markov chain, and derive the corresponding \"channel dispersion.\" The \"channel dispersion\" is then used to assess the throughput performance of various communication strategies. The results show that for a fixed packet size the system throughput increases with transport block size.","Title: DoA estimation and achievable rate analysis for 3D millimeter wave massive MIMO systems\nYear: 2014\n\nAbstract: Mobile data traffic is predicted to grow exponentially in the future. To address the challenge and consider the form factor limitation at the base station, 3D millimeter wave massive MIMO has been introduced as an enabling technology for 5G systems. In 3D millimeter wave massive MIMO systems, due to the large number of antennas and limited number of clusters, a base station will mainly rely on the uplink sounding signals instead of the feedback to figure out the channel knowledge to perform 3D MIMO operation. Accordingly, multi-dimensional channel estimation becomes critical for such systems to realize the predicted rate gains. In this paper, the performance of direction of arrival (DoA) estimation at the base station using ESPRIT method is characterized. The DoA estimation is further related to the underlying 3D MIMO achievable rate and the optimal transmission strategy is characterized. Finally, the impact of channel estimation error on the underlying achievable rate is analyzed. Our results suggest that DoA estimation is crucial for the transmit beam-forming of 3D millimeter wave massive MIMO systems. Furthermore, the optimal transmission strategy depends heavily on the performance of the underlying DoA estimation.","Title: Coding Across Finite Transport Blocks in Modern Wireless Communication Systems\nYear: 2014\n\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In light of this challenge, this paper investigates the throughput performance of wireless communication systems under channel coding over finite transport blocks (TBs) with the channel state sequence available only at the receiver. When we apply coding across multiple TBs, the underlying wireless channel can be effectively modeled as a finite-state Markov chain. By linking the characteristics of the underlying physical channel to the parameters of the Markov chain, we characterize the channel dispersion of the corresponding system. The channel dispersion is then used to assess the coding performance of various communication strategies. We also propose a communication scheme where the receiver determines the decoding time based on the available channel state sequence. Numerical results show that the proposed scheme significantly reduces the coding delay to achieve rates near the channel capacity.","Title: Early decoding for transmission over finite transport blocks\nYear: 2014\n\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In the light of this challenge, this paper investigates the throughput performance of wireless systems under channel coding over finite transport blocks (TBs) with the channel state sequence available only at the receiver. We analyze the performance of a communication scheme with feedback, namely early decoding, where for each codeblock the receiver makes a single decoding attempt at a time determined based on the available channel state information. A finite-state Markov channel (FSMC) is introduced to model the TB-based wireless system where the parameters of the model are linked to the characteristics of the underlying physical channel. The FSMC model is then used to assess the maximum achievable throughput of the early decoding strategy. Numerical results suggest that despite its low computational complexity the proposed scheme significantly reduces the coding latency to achieve rates near the channel capacity.","Title: On the finite blocklength performance of HARQ in modern wireless systems\nYear: 2014\n\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In the light of this challenge, this paper investigates the throughput performance of hybrid automatic repeat request (HARQ) systems under finite blocklength constraint. We present a framework to compute the maximum achievable rate with HARQ over the Rayleigh fading channel for a given probability of error. In the proposed framework, the operation of HARQ over the Rayleigh fading channel is modeled as a finite-state Markov chain. The state transition probabilities of the proposed Markov model are estimated from the fading characteristics of the wireless channel as well as the dispersion associated with different channel state sequence realizations. With this framework we are able to link the HARQ throughput performance to the characteristics of the underlying physical channel as well as the system design parameters such as modulation and transmit power. Furthermore, we discuss the relationship between the system throughput, and the number of HARQ rounds. The results show that the required number of HARQ rounds to take full advantage of HARQ depends on the choice of modulation, and varies as a function of the signal-to-noise ratio (SNR).","Title: Cooperative Transmission for Wireless Networks Using Mutual-Information Accumulation\nYear: 2011\n\nAbstract: Cooperation between the nodes of wireless multihop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual information accumulation. In this paper, we investigate resource allocation for unicast and multicast transmission in such networks. Given a network, a source, and a destination, our objective is to minimize end-to-end transmission delay under energy and bandwidth constraints. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any transmission order we show that solving for the optimum resource allocation can be formulated as a linear programming problem. We then show that the transmission order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear programs leads to a locally optimal solution in a very efficient manner. In comparison to the proposed cooperative routing solution, it is observed that conventional shortest path multihop routing typically incurs additional delays and energy expenditures on the order of 70%. Drawing inspiration from this first, centralized, algorithm, we also present two distributed algorithms. These algorithms require only local channel state information. Simulations indicate that they yield solutions about two to five percent less efficient than the centralized algorithm.","Title: Subspace Identification for DOA Estimation in Massive / Full-dimension MIMO System: Bad Data Mitigation and Automatic Source Enumeration\nYear: 2015\n\nAbstract: this paper, the direction-of-arrival (DOA) estimation problem for massive multiple-input multipleoutput (MIMO) systems with a two dimensional (2D) array (also known as full-dimension MIMO) is investigated, assuming no knowledge of path number, noise power, path gain correlations and bad data statistics. Based on the variational Bayesian framework, a novel iterative algorithm for subspace identification operating on tensor represented data is proposed with integrated features of effective bad data mitigation and automatic source enumeration. The subspace recovered from the proposed algorithm not only enables existing 2D DOA estimators to be readily applied, if the number of signal paths is less than the number of horizontal antennas and vertical antennas, the subspaces in elevation and azimuth domains can be separately estimated, from which one dimensional (1D) DOA estimators can be utilized, thus further lowering the complexity. Simulation results are presented to illustrate the excellent performance of the proposed subspace recovery method and subsequent DOA estimation in terms of accuracy and robustness.","Title: Cooperative Routing For Underlay Cognitive Radio Networks Using Mutual-Information Accumulation\nYear: 2015\n\nAbstract: In underlay cognitive radio networks (CRNs),secondary users (SUs)have to dynamically control their transmit powers so that the interference to primary users (PUs) is tolerable. Under this constraint, SUs' data link usually suffers from either high error rate with limited transmission range or long end-to-end delay caused by multi-hop transmissions. To improve the performance of SUs, cooperative routing using mutual-information accumulation is introduced in CRNs for the first time in this paper. To be specific, the routing and resource allocation problem in underlay CRNs is investigated and is factored into two sub-problems, each of which can be solved efficiently. Furthermore, a distributed algorithm is introduced and simulation results show that both the centralized and distributed algorithms can reduce upto 77% of the end-to-end delay compared to the traditional multi-hop delay-optimal routing in CRNs. Finally, theoretical analysis on the end-to-end delay for a one-dimensional (1-D) network in the low signal-to-interference ratio (SIR) region is conducted. Both the analytical and simulation results show that mutual-information accumulation can significantly decrease the delay of underlay CRNs, especially in the scenario where PUs have a tight interference power constraint.","Title: Resource Allocation for Delay-Sensitive Traffic over LTE-Advanced Relay Networks\nYear: 2015\n\nAbstract: Future wireless networks will face the dual challenge of supporting large traffic volumes while providing reliable service for delay-sensitive traffic. To meet the challenge, relay network has been introduced as a new network architecture for the fourth generation (4G) LTE-Advanced (LTE-A) networks. In this paper, we investigate resource allocation including subcarrier and power allocation for LTE-A relay networks under statistical quality of service (QoS) constraints. By dual decomposition, we derive the optimal subcarrier and power allocation strategies to maximize the effective capacity (EC) of the underlying LTEA relay systems. Characteristics of optimal resource allocation strategies are identified, and a low-complexity suboptimal scheme is developed through optimizing the subcarrier and power allocation individually. Our result suggests that the optimal subcarrier and power allocation strategies depend heavily on the underlying QoS constraint. For example, in the low signal-to-interference-plus-noise (SINR) regime, when there are less stringent QoS constraints, base stations and relay stations tend to allocate all the power to the best available subcarrier. However, as QoS requirements become more stringent, both base stations and relay stations will spread their power over available subcarriers. On the other hand, in the high SINR regime, regardless of the QoS constraints, base stations and relay stations tend to equally allocate power among available subcarriers.","Title: Energy-Efficient Resource Allocation for MIMO-OFDM Systems Serving Random Sources With Statistical QoS Requirement\nYear: 2015\n\nAbstract: This paper optimizes resource allocation that maximizes the energy efficiency (EE) of wireless systems with statistical quality of service (QoS) requirement, where a delay bound and its violation probability need to be guaranteed. To avoid wasting energy when serving random sources over wireless channels, we convert the QoS exponent, a key parameter to characterize statistical QoS guarantee under the framework of effective bandwidth and effective capacity, into multi-state QoS exponents dependent on the queue length. To illustrate how to optimize resource allocation, we consider multi-input-multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A general method to optimize the queue length based bandwidth and power allocation (QRA) policy is proposed, which maximizes the EE under the statistical QoS constraint. A closed-form optimal QRA policy is derived for massive MIMO-OFDM system with infinite antennas serving the first order autoregressive source. The EE limit obtained from infinite delay bound and the achieved EEs of different policies under finite delay bounds are analyzed. Simulation and numerical results show that the EE achieved by the QRA policy approaches the EE limit when the delay bound is large, and is much higher than those achieved by existing policies considering statistical QoS provision when the delay bound is stringent.","Title: Optimal resource allocation for sensing-based spectrum sharing D2D networks.\nYear: 2015\n\nAbstract: To improve the spectral efficiency of a cellular network, sensing based spectrum sharing device-to-device (sensing-based D2D) technique is introduced in this paper. To be specific, efficient algorithms are introduced to find the optimal sensing time and power allocation for single-subband sensing-based D2D systems under cellular link’s rate loss constraint. For multi-subband systems, D2D users may have limited sensing capability where only a part of the subbands can be sensed. Accordingly, a partially observable Markov decision process (POMDP) model is introduced and an efficient algorithm is introduced to address the resource allocation problem.","Title: Smart backhauling and fronthauling for 5G networks: from precoding to network architecture [Guest editorial]\nYear: 2015\n\nAbstract: The recent widespread use of mobile Internet together with the advent of many smart applications has led to the explosive growth of mobile data traffic in the last few years. This remarkable growing momentum of mobile traffic will most likely continue due to the emerging needs of connecting people, machines, and applications through mobile infrastructure. As a result, the current and projected dra...","Title: Energy-efficient resource allocation of wireless systems with statistical QoS requirement\nYear: 2014\n\nAbstract: This paper strives to improve the energy efficiency (EE) of wireless systems by resource allocation for delay sensitive traffic with the statistical quality of service (QoS) requirement, where a delay bound and a small violation probability is ensured. To avoid wasting energy when serving random traffic, we turn the QoS exponent, a key parameter to characterize statistical QoS guarantee under the framework of effective bandwidth and effective capacity, into a QoS function dependent on the queue length. A method to design queue length based resource allocation strategy is proposed, which maximizes the EE under the constraint on the QoS function. By taking an OFDM system serving Poisson source as an example, a closed form subcarrier allocation strategy with constant transmit power on each subcarrier is derived. Simulation and numerical results show that the EE achieved by the proposed strategy is much higher than the relevant strategies in the literature considering statistical QoS provision, and is very close to the EE upper bound achieved when the delay bound is infinite.","Title: Interference Alignment And Leakage-Based Iterative Coordinated Beam-Forming For Multi-User Mimo In Lte-Advanced\nYear: 2015\n\nAbstract: To suppress co-channel interference and achieve good system performance in a Multi-User Multiple Input Multiple Output (MU-MIMO) downlink network, we introduce a novel Interference Alignment (IA) receive matrix design methodology along with a low complexity iterative coordinated beamforming scheme. The introduced scheme takes into account the codebook-based feedback for LTE/LTE-Advanced systems. In our design, IA is utilized to mitigate the inter-cell interference while leakage-based iterative coordinated beamforming is used to combat the intra-cell interference. Optimal transmit beamforming vectors are characterized and a closed-form expression for these beamforming vectors in the presence of quantization error due to the codebook-based feedback is also presented. Simulation is conducted to illustrate the performance of introduced coordinated beamforming strategy. It suggests that for 4 by 2 MIMO systems, rank 2 codebook-based feedback yields much better performance than rank 1 feedback. Furthermore, for a fixed payload size of the codebook, unlike zero-forcing beamforming where the sum throughput is bounded as the signal-to-noise ratio (SNR) increases, in our scheme the performance gap between the rank 2 feedback and perfect feedback remains almost constant as SNR increases.","Title: On The Queueing Performance Of Harq Systems With Coding Over Finite Transport Blocks\nYear: 2015\n\nAbstract: With the growing popularity of mobile applications such as voice over IP (VoIP) and real-time conversational video, and due to the scarcity of the available radio spectrum, increasing the spectral efficiency of wireless systems under quality of service (QoS) constraints becomes increasingly important. Accordingly, in this paper we investigate the maximum achievable rate of incremental redundancy type hybrid automatic repeat request (IR-HARQ) over the Rayleigh fading channel under probability of error, and queueing delay violation probability constraints, in the finite code blocklength regime.We model the Rayleigh fading channel by a finite-state Markov channel (FSMC) where the channel in each state is modeled as additive white Gaussian noise (AWGN). We derive the dispersion of parallel AWGN channels with finite input alphabets (e.g. pulse amplitude modulation (PAM)), which is used to track the operation of IR-HARQ over the wireless channel for a given modulation scheme, and coding rate. We then use a two-dimensional Markov process tracking the time evolution of a queueing system, where data packets arriving at the queue are transmitted over the wireless channel with IR-HARQ. This Markov process is used to derive an upper bound on the queueing delay violation probability and to jointly approximate the average rate and the average probability of error of HARQ as a function of the modulation scheme and the coding rate. Finally, we present numerical results.","Title: Modeling and Analysis of Energy Consumption for RF Transceivers in Wireless Cellular Systems.\nYear: 2015\n\nAbstract: In this paper, a comprehensive model has been provided to study the energy consumption of wireless cellular devices, by analyzing the relationship between the modulation order and energy consumption of the power amplifier (PA) and other circuits in radio frequency transceivers. Two types of energy consumption for PAs are studied in detail: transmitted energy, which is provided to the antenna to transmit data, and energy dissipated as a heat. First, the transmitted energy is studied along with different modulation orders for different distances between the transmitter and receiver. Next, the dissipated energy with all corresponding parameters such as peak to average ratio (PAR) and the drain efficiency of the PA is discussed. Other circuits are examined to show that the energy of these circuits-unlike other models in the literature-change with modulation order. The results reinforce the idea that increasing the modulation order leads to higher energy consumption in the RF transceiver for large distance. The results also show that the energy dissipated due to PAR and drain efficiency is larger than the transmitted energy.","Title: DoA Estimation and RMSE Characterization for 3D Massive-MIMO/FD-MIMO OFDM System.\nYear: 2015\n\nAbstract: With the promise of meeting future capacity demands for mobile broadband communications, 3D massive-MIMO/Full Dimension MIMO (FD-MIMO) systems have gained much interest among the researchers in recent years. Apart from the huge spectral efficiency gain offered by the system, the reason for this great interest can also be attributed to significant reduction of latency, simplified multiple access layer, and robustness to interference. However, in order to completely extract the benefits of massive-MIMO systems, accurate channel state information is very critical. In this paper, a channel estimation method based on direction of arrival (DoA) estimation is presented for massive-MIMO OFDM systems. To be specific, the DoA is estimated using Estimation of Signal Parameter via Rotational Invariance Technique (ESPRIT) method, and the root mean square error (RMSE) of the DoA estimation is analytically characterized for the corresponding MIMO-OFDM system.","Title: Robust Tensor-Based DOA Estimation in Massive / Full-Dimension MIMO System.\nYear: 2015\n\nAbstract: In this paper, direction-of-arrival (DOA) estimation problem for massive multiple-input multiple-output (MIMO) systems with a two dimensional (2D) array is investigated, assuming no knowledge of path number, noise power, path gain correlations and bad data statistics. A novel iterative algorithm operating on tensor represented data is proposed, with integrated features of effective bad data mitigation and automatic source enumeration. Simulation results are presented to illustrate the excellent performance of the proposed algorithm in term of accuracy and robustness.","Title: Resource Allocation For Sensing-Based Device-To-Device (D2d) Networks\nYear: 2015\n\nAbstract: Resource allocation for sensing-based D2D networks is investigated in this paper. To be specific, we introduce the concept of spatial spectrum sensing where D2D users can sense spatial spectrum opportunities in a cellular network. By modeling the location of base stations and cellular users as Poisson point processes (PPP), the spatial spectrum sensing problem can be formulated using the framework of detection theory. The closed-form expressions are obtained for probabilities of spatial detection, probability of spatial false alarm, and sensing threshold. Accordingly, simulation results are provided to verity our analysis.","Title: DoA estimation and achievable rate analysis for 3D massive MIMO in aeronautical communication systems\nYear: 2015\n\nAbstract: With very high carrier frequencies (such as millimeter-wave (mmW) bands), a very large number of antennas can be packed at the base station (BS). For this kind of high dimensional channel, it is desirable to exploit signal directions to estimate the channel directions. In this paper, we analyze the performance of the direction of arrival (DoA) estimation based on unitary ESPRIT algorithm assuming time division duplex (TDD) wideband system. The mean-squared error (MSE) of the 2D DoA estimation of a multipath signal impinging on a planar antenna array is derived. Accordingly, we propose a power allocation strategy that counts for the DoA estimation error. The achievable rate characterization suggests that our power allocation strategy outperforms the traditional water-filling solution.","Title: DoA estimation and capacity analysis for 3D massive-MIMO/FD-MIMO OFDM system\nYear: 2015\n\nAbstract: With the promise of meeting future capacity demands for mobile broadband communications, 3D massive-MIMO/Full Dimension MIMO (FD-MIMO) systems have gained much interest among the researchers in recent years. Apart from the huge spectral efficiency gain offered by the system, the reason for this great interest can also be attributed to significant reduction of latency, simplified multiple access layer, and robustness to interference. However, in order to completely extract the benefits of massive-MIMO systems, accurate channel state information is very critical. In this paper, a channel estimation method based on direction of arrival (DoA) estimation is presented for massive-MIMO OFDM systems. To be specific, the DoA is estimated using Estimation of Signal Parameter via Rotational Invariance Technique (ESPRIT) method, and the capacity of the system is analytically characterized. It has been shown that optimum precoding matrix for the massive MIMO OFDM system can be constructed from the DoA estimation at the base station.","Title: Dynamic Allocation of RACH Resource for Clustered M2M Communications in LTE Networks.\nYear: 2015\n\nAbstract: In this paper, we propose a dynamic allocation scheme of random access channel (RACH) resource for clustered machine-to-machine (M2M) communications, in which delay-sensitive services coexist with delay-tolerant ones. Our scheme aims at alleviating the overload and congestion of machine-type (MTC) communication as well as satisfying both delay-sensitive and delay-tolerant services. Specifically, the operation of our protocol includes three aspects. First, in order to make full use of the preamble resources controlled by the Enhanced Node B (eNB), our proposed scheme adopts a two-cluster networking, where MTC devices are divided into two clusters based on their requirements on delay. Second, we develop the dynamic allocation scheme to partition the available preambles for each cluster under the condition of guaranteeing the preferable number of successful devices. Third, the devices belonging to different clusters adopt the access class barring (ACB) mechanism respectively. Simulation results show that our proposed scheme realizes the remarkable increase in improving the access success probability and achieve performance improvement in reducing access delay.","Title: Device-To-Device Relay Assisted Cellular Networks With Token-Based Incentives\nYear: 2015\n\nAbstract: We consider a device-to-device (D2D) relayassisted cellular network where mobile transceivers that are owned by self-interested users are incentivized to relay each other's data using tokens, which they exchange electronically to \"buy\" and \"sell\" downlink relay services. We formulate the decision problem faced by each UE, namely, the problem of deciding whether or not to relay, as a Markov decision process (MDP). We propose a supervised learning algorithm that devices can deploy to learn their optimal relay policies online given their experienced network environment. Our simulation results show that, within the proposed token system, self-interested devices can achieve almost 15% higher throughput on average, and almost 40% higher throughput at the 90th percentile, than with only direct base-station-to-device communications. Additionally, we show that the token system performs best when the network contains neither too few nor too many tokens.","Title: Proportional-Fair Resource Allocation for Coordinated Multi-Point Transmission in LTE-Advanced.\nYear: 2016\n\nAbstract: Coordinated multi-point (CoMP) transmission and reception are introduced as a promising technology in the 3GPP LTE-advanced standard, to manage interference, improve the overall system performance, and enhance system reliability. In this paper, a resource allocation problem is studied for downlink CoMP coordinated beamforming systems, where each base station (BS) serves its own mobile stations. Multiple-input-multiple-output (MIMO) transmit precoding and resource allocation are linked to the underlying proportional-fair scheduling to ensure a good trade-off between cell-average and cell-edge user spectral-efficiency. Due to the coupled interference among mobile stations, the resulting proportional-fair resource allocation optimization problem becomes nonconvex. To solve for optimal operating point for MIMO CoMP network, a parallel successive convex approximation-based algorithm is introduced. The introduced scheme enables all BSs to update their optimization variables in parallel by solving a sequence of strongly convex subproblems. Closed-form expressions of the locally optimal solution in both the high and low signal-to-noise regimes are characterized. The performance of the introduced scheme is also investigated through simulations. Numerical results show the efficiency of the introduced algorithm.","Title: Spatial Spectrum Sensing-Based Device-to-Device Cellular Networks.\nYear: 2016\n\nAbstract: Ultra-densification is one of the main features of 5G networks. In an ultra-dense network, how to conduct interference management and spectrum allocation is a challenging issue. Spectrum sensing in cognitive radio networks is a distributed and efficient way to resolve this issue in ultra-dense networks. However, most of the studies on spectrum sensing only focus on sensing temporal spectrum opportunities where one or multiple primary users are active, which does not make full use of spectrum opportunities in the spatial location domain. To overcome the shortcomings of conventional temporal spectrum sensing, we study the problem of spatial spectrum sensing, which senses spatial spectrum opportunities in wireless networks. In this paper, the performance of spatial spectrum sensing and its application in sensing-based device-to-device (D2D) cellular networks are analyzed using stochastic geometry. Specifically, by modeling the locations of active transmitters as a Poisson point process, the spatial spectrum sensing problem is formulated using the framework of a detection theory. Closed-form expressions are obtained for the sensing threshold, probabilities of spatial detection, and false alarm. Furthermore, analytical throughput for D2D users and cellular users under both channel inversion and constant power allocation cases are derived. The optimal sensing radius that maximizes the defined network metric is obtained numerically. Finally, the simulation and numerical results are presented to verify our theoretical analysis.","Title: DoA Estimation and Capacity Analysis for 3-D Millimeter Wave Massive-MIMO/FD-MIMO OFDM Systems.\nYear: 2016\n\nAbstract: With the promise of meeting future capacity demands, 3-D massive-MIMO/full dimension multiple-input-multiple-output (FD-MIMO) systems have gained much interest in recent years. Apart from the huge spectral efficiency gain, 3-D massive-MIMO/FD-MIMO systems can also lead to significant reduction of latency, simplified multiple access layer, and robustness to interference. However, in order to comple...","Title: Dynamic RACH Partition for Massive Access of Differentiated M2M Services.\nYear: 2016\n\nAbstract: In machine-to-machine (M2M) networks, a key challenge is to overcome the overload problem caused by random access requests from massive machine-type communication (MTC) devices. When differentiated services coexist, such as delay-sensitive and delay-tolerant services, the problem becomes more complicated and challenging. This is because delay-sensitive services often use more aggressive policies, and thus, delay-tolerant services get much fewer chances to access the network. To conquer the problem, we propose an efficient mechanism for massive access control over differentiated M2M services, including delay-sensitive and delay-tolerant services. Specifically, based on the traffic loads of the two types of services, the proposed scheme dynamically partitions and allocates the random access channel (RACH) resource to each type of services. The RACH partition strategy is thoroughly optimized to increase the access performances of M2M networks. Analyses and simulation demonstrate the effectiveness of our design. The proposed scheme can outperform the baseline access class barring (ACB) scheme, which ignores service types in access control, in terms of access success probability and the average access delay.","Title: Novel Spike based Reservoir Node Design with High Performance Spike Delay Loop.\nYear: 2016\n\nAbstract: With the emerging cutting-edge semiconductor nanotechnologies, reservoir computing has shifted the focus from software implementation towards hardware and optical implementations over the last few decades. Nowadays, in the field of reservoir computing, pure analog implementation with the employment of CMOS nanotechnology has attracted a worldwide attention. In this paper, we introduce a spike-based analog reservoir node with compact delay performing at extremely high accuracy. The detailed work on this novel spike processor working in near chaotic condition is presented and analyzed. Furthermore, we announce a novel class of spike-based delay loop which enables the pure spike implementation of reservoir computing. The simulation results demonstrated that our delay loop possesses exceptionally high accuracy of 99.24% and gain-hold property without adopting any kind of amplifiers. Our proposed reservoir node has shown the potential of transforming spike signals to a high-dimensional state space.","Title: Performance Analysis on Nano-Networks: A Stochastic Geometry Approach.\nYear: 2016\n\nAbstract: Pulse based communication scheme, e.g., On-OFF Keying modulation Spread in Time (TS-OOK), is currently the only solution for nano-networks. In this paper, we present an initial analysis on the performance of pulse based communication scheme in nano-networks using stochastic geometry. To be specific, by modeling the transmission of pulse as random events, we theoretically characterize the cumulative distribution function of signal-to-interference-plus-noise ratio and link throughput in nano-networks. Furthermore, both simulation and numerical results are presented to verify our analysis. Our results show that low-weight codes for TS-OOK can significantly increase the average throughput in dense nano-networks where the interference cannot be neglected.","Title: Interference Alignment for Downlink Multi-Cell LTE-Advanced Systems With Limited Feedback.\nYear: 2016\n\nAbstract: To suppress the co-channel interference in a multi-cell multi-user multiple-input-multiple-output downlink cellular network, a novel interference alignment transceiver beam-forming design along with a low complexity iterative coordinated beam-forming scheme is introduced. While the latter combats the intra-cell interference, the former is utilized to mitigate the inter-cell interference. The proposed schemes consider the codebook-based feedback, which is adopted in the LTE/LTE-advanced systems. Optimal downlink user-specific and cell-specific beam-forming matrices are characterized to maximize the lower bound of expected signal-to-leakage-plus-noise ratio and to minimize the residual inter-cell interference, respectively. Moreover, closed-form expressions for these beam-forming matrices under limited channel state information feedback and in the presence of the quantization error are identified. Simulations are conducted to investigate the performance of the proposed strategy. The results indicate that our scheme can significantly improve the average spectral-efficiency of the underlying network when compared with existing ones where the quantization error is neglected. Furthermore, for a fixed payload size of the codebook, unlike zero-forcing beam-forming in which the sum throughput is bounded as the signal-to-noise ratio (SNR) increases, in our scheme, the performance gap between rank 2 feedback and perfect feedback remains approximately constant as SNR increases.","Title: Urban Link Travel Time Prediction Based on a Gradient Boosting Method Considering Spatiotemporal Correlations.\nYear: 2016\n\nAbstract: The prediction of travel times is challenging because of the sparseness of real-time traffic data and the intrinsic uncertainty of travel on congested urban road networks. We propose a new gradient-boosted regression tree method to accurately predict travel times. This model accounts for spatiotemporal correlations extracted from historical and real-time traffic data for adjacent and target links. This method can deliver high prediction accuracy by combining simple regression trees with poor performance. It corrects the error found in existing models for improved prediction accuracy. Our spatiotemporal gradient-boosted regression tree model was verified in experiments. The training data were obtained from big data reflecting historic traffic conditions collected by probe vehicles in Wuhan from January to May 2014. Real-time data were extracted from 11 weeks of GPS records collected in Wuhan from 5 May 2014 to 20 July 2014. Based on these data, we predicted link travel time for the period from 21 July 2014 to 25 July 2014. Experiments showed that our proposed spatiotemporal gradient-boosted regression tree model obtained better results than gradient boosting, random forest, or autoregressive integrated moving average approaches. Furthermore, these results indicate the advantages of our model for urban link travel time prediction.","Title: Energy Efficient Spiking Temporal Encoder Design for Neuromorphic Computing Systems.\nYear: 2016\n\nAbstract: Neuromorphic computing hardware has undergone a rapid development and progress in the past few years. One of the key components in neuromorphic computing systems is the neural encoder which transforms sensory information into spike trains. In this paper, both rate encoding and temporal encoding schemes are discussed. Two novel temporal encoding schemes, parallel and iteration, are presented. The p...","Title: FPGA based spike-time dependent encoder and reservoir design in neuromorphic computing processors.\nYear: 2016\n\nAbstract: In this paper, we propose a Field Programmable Gate Array (FPGA) platform for spike time dependent encoder and dynamic reservoir in neuromorphic computing processors. Neuromorphic computing processors represent a type of non-traditional architecture encompassing evolutionary systems and hold great promise for many important engineering and scientific applications. The reservoir computing approach with dynamic reservoir is a paradigm in machine learning whose processing capabilities rely on the dynamical behavior of Recurrent Neural Networks (RNNs). It has made swift progress and development in both the theoretical realm and its subsequent implementations. However, most of the implementations are based on software, due to the difficulties in performing real-time training of the output weights on hardware platforms. The reservoir computing approach implemented in this paper utilizes the Echo State Network (ESN) architecture which includes a reservoir and its consequent training process. It can be trained and implemented in FPGA without any software cooperation. As FPGA is a digital logic platform and the information entered into a RNN is analog, we also propose an encoding circuit and an Analog to Digital Converter (ADC) to bridge this divide. The proposed method given for the realization of the neuromorphic computing chips, therefore, provides a viable option.","Title: Privacy Protection Scheme for eHealth Systems: A Stochastic Geometry Approach.\nYear: 2016\n\nAbstract: The technological advancements in the health care system have made possible the massive integration of biomedical sensors for monitoring patients' health and disease progression. In this paper, we consider a three tier medical body area network (MBAN): intra-MBAN, inter-MBAN, and beyond-MBAN. The intra-MBAN transmits sensors' data to a controller, which in turn transmits them in the inter-MBAN tier to an access device like a PDA or a tablet device, usually connected to a patient's medical database. The access device then serves as a mean of communication between intra-MBAN and beyond-MBAN to access the hospital information systems. This widely deployed design in hospitals places security and privacy violation threats on the spotlight of attention, especially in the inter-MBAN tier. This has motivated us to optimize the average MBAN controller transmit power that minimizes the probability of eavesdroppers overhearing the communication, using tools from stochastic geometry. We analyze this privacy protection scheme for eHealth systems through simulations. Results show that the proposed scheme achieves higher privacy protection, but at the expense of reduced coverage.","Title: Coordinated Data Assignment: A Novel Scheme for Big Data over Cached Cloud-RAN.\nYear: 2016\n\nAbstract: A cloud radio access network (Cloud-RAN) is a network architecture that holds onto the promise of meeting the explosive growth of mobile data traffic. Cloud-RAN consists a central processor (CP) connecting to multiple multi-antenna base stations (BSs) via finite-capacity backhaul links. To reduce the backhaul traffic, BS-level caching technique is utilized in which the popular contents are pre-fetched in memories at each BS. This technique plays an important role in future wireless big data processing due to its simplicity, low cost, and natural integration with big data analytical tools. Considered the tradeoff between the backhaul and the transmission power cost, in this paper we define the network cost of the system as a normalized weighted sum. The problem of minimizing the network cost with respect to both the precoding matrix and the cache placement matrix is formulated subject to the quality of service (QoS), peak transmission power, and cache capacity constraints. The l 0-norm in the objective function along with the QoS constraints renders the optimization problem non-convex. Additionally, since the entries of cache placement matrix take binary values, the optimization problem falls into a mixed integer nonlinear programming (MINLP) which is a NP-hard problem. An iterative coordinated data assignment algorithm is introduced which achieves a stationary point of the problem. Simulations are conducted to illustrate the performance of introduced algorithm. It suggests that the introduced scheme can significantly reduce the total network cost of the underlying Cloud-RAN network and demonstrate the importance of considering the designing of cache placement matrix.","Title: On the Performance of Relay-Assisted D2D Networks under Spatially Correlated Interference.\nYear: 2016\n\nAbstract: With the explosive growth of mobile traffic demand, device-to-device (D2D) communication offers a promising approach to reduce cellular congestion by offloading users' traffic to D2D network. In this paper, we consider a relay-assisted D2D communication in underlay cellular networks, where D2D users access a proportion of the spectrum occupied by cellular users. This poses two fundamental issues. The first issue is related to protecting the cellular transmissions by reducing the spectrum partition factor, which measures the fraction of spectrum available to D2D users. The second issue is that as we limit the spectrum available to D2D users, less D2D transmissions can be supported, which in turn increases the distances between them. To address these issues, we allow a relay user to assist D2D communications in order to achieve higher D2D spectral efficiency without affecting cellular spectral efficiency. In fact, results show significant improvements in spectral efficiency not only to D2D, but to the whole network, especially in a dense D2D environment.","Title: Improving Spectral Efficiency of D2D Cellular Networks through RF Energy Harvesting.\nYear: 2016\n\nAbstract: In this paper, we consider device-to-device (D2D) communication underlaying cellular networks, where D2D users harvest radio frequency (RF) power from uplink cellular transmissions. This paper addresses two important issues for energy harvesting-based D2D cellular networks. The first is how the energy harvested from cellular ambient RF signals affects the D2D spectral efficiency. Using tools from stochastic geometry, we investigate this issue by first characterizing the transmission probability of D2D transmitter as the probability of having enough battery power, and then obtaining analytic expressions of the spectral efficiency for D2D and cellular networks. The second issue is related to the cellular spectral efficiency: the more RF energy D2D users can harvest, the higher their transmission probability becomes, which leads to generating more interference in the cellular network. We carry out simulations to understand this impact of RF energy harvesting on the spectral efficiency of both D2D and cellular networks. Results show promising improvement to the whole network, in terms of the weighted spectral efficiency, when employing RF harvesting technology and when there are enough available channels in the network.","Title: Cooperative Retransmission for Massive MTC under Spatiotemporally Correlated Interference.\nYear: 2016\n\nAbstract: In a massive machine type communication (massive MTC) network, wireless connections between machine type devices (MTDs) and eNodeBs are unreliable due to the interference caused by uncoordinated access of other MTDs. Furthermore, it is with a high probability that the retransmission from the outage source MTD will fail again due to the spatiotemporally correlated interference. In this paper, we design and analyze a location-based cooperative strategy to improve the performance of massive MTC networks. In the cooperative strategy, an inactive MTD is selected as a relay if it has successfully decoded the packet and if it is located within a circular area around the eNodeB. Considering the spatial and temporal correlation of interference, the outage probability of the designed cooperative strategy is derived using stochastic geometry. Both the simulation and numerical results demonstrate that spatiotemporal correlation of interference significantly affects the performance analysis of cooperative massive MTC networks and our designed cooperative strategy can significantly reduce the outage probability compared to conventional retransmission.","Title: Fundamentals of Spatial RF Energy Harvesting for D2D Cellular Networks.\nYear: 2016\n\nAbstract: Energy efficiency is one of the major challenges of 5G networks. As data rates are expected to increase by 1000x from 4G to 5G, energy efficiency will need to improve by about the same amount. Recently, energy harvesting techniques have attracted lots of attention from the scientific community, due to their ability to increase network lifetime. More specific, energy harvesting from ambient radio frequency (RF) signals is of special importance, especially with the recent RF circuit advancements. In this paper, we consider a device-to-device (D2D) communication in underlay cellular networks, where D2D users reuse the spectrum occupied by cellular users. We introduce the concept of spatial RF energy harvesting, where D2D users harvest RF power from uplink cellular transmissions, if it exceeds a predesigned threshold, in a spatial region. Using tools from stochastic geometry, we obtain a closed form expression for the probability of activating RF power conversion circuit by making full use of spatial locations of ambient RF signals. Subsequently, we study the impact of RF energy harvesting region radius to harvest sufficient power on the signal-to-interference (SIR) ratio of D2D network. Simulation results provide insights for the required advancements to design highly efficient RF harvesting circuits.","Title: Enabling cyber-physical communication in 5G cellular networks: challenges, spatial spectrum sensing, and cyber-security\nYear: 2017\n\nAbstract: Cyber-physical systems (CPS) help create new services and applications by revolutionising our world in different fields through their tight interactions and automated decisions. This is especially true with the ongoing increase in the number of physical things (sensors, actuators, smartphones, tablets, and so on) along with the explosive increase in the usage of online networking services and appl...","Title: Energy Harvesting-Based D2D-Assisted Machine-Type Communications.\nYear: 2017\n\nAbstract: Supporting massive numbers of machine-type communication (MTC) devices poses several challenges for future 5G networks, including network control, scheduling, and powering these devices. A potential solution is to offload MTC traffic onto device-to-device (D2D) communication links to better manage radio resources and reduce MTC devices' energy consumption. However, this approach requires D2D users...","Title: Interspike-Interval-Based Analog Spike-Time-Dependent Encoder for Neuromorphic Processors.\nYear: 2017\n\nAbstract: Von Neumann bottleneck, which refers to the limited throughput between the CPU and memory, has already become a major factor hindering the technical advances of computing systems. In recent years, neuromorphic systems have started to gain the increasing attentions as compact and energy-efficient computing platforms. As one of the most crucial components in the neuromorphic computing systems, neura...","Title: On the Spectral and Energy Efficiency of Full-Duplex Small-Cell Wireless Systems With Massive MIMO.\nYear: 2017\n\nAbstract: The achievable rate of full-duplex (FD) small-cell systems with massive multiple-input multiple-output (MIMO), in which a low-power base station (BS) equipped with large antenna arrays sends/receives data to and from multiple half-duplex (HD) users at the same time on the same frequency, is investigated. The BS uses imperfect channel state information (CSI) obtained from received pilots, nonideal ...","Title: Channel estimation in full-dimensional massive MIMO system using one training symbol.\nYear: 2017\n\nAbstract: In this paper, an algorithm is proposed to estimate thousands of channel parameters in massive multiple-input multiple-output (MIMO) systems with a three-dimensional antenna array, using only one training symbol while assuming no knowledge of path number, noise power, path gain and direction-of-arrival (DOA) statistics. Furthermore, the received data structure is exploited to give a low-complexity DOA acquisition scheme with closed-form computations. Simulation results show excellent performance of the proposed algorithm in both channel estimation and DOA acquisition.","Title: Reservoir Computing Meets Smart Grids: Attack Detection Using Delayed Feedback Networks.\nYear: 2018\n\nAbstract: A new method for attack detection of smart grids with wind power generators using reservoir computing (RC) is introduced in this paper. RC is an energy-efficient computing paradigm within the field of neuromorphic computing and the delayed feedback networks (DFNs) implementation of RC has shown superior performance in many classification tasks. The combination of temporal encoding, DFN, and a mult...","Title: Distributed MIMO Precoding for In-Band Full-Duplex Wireless Backhaul in Heterogeneous Networks.\nYear: 2018\n\nAbstract: This paper investigates distributed MIMO precoding design to maximize the weighted sum rate in a heterogeneous network where the multiple input multiple output full-duplex (MIMO-FD) small cells reuse the downlink spectrum of the macro base-station (BS) to exchange backhaul information. The multi-antenna BS transmits signals to the cellular users using the dirty paper coding technique and the MIMO-...","Title: Modeling and Analysis of Power Amplifier Dissipation Energy in Wireless Handset Transceivers\nYear: 2018\n\nAbstract: The growing demand for high spectral efficiency in 5G communication systems imposes greater energy consumption requirements in wireless handsets. Using spectrally efficient modulations such as multilevel quadrature amplitude modulation (MQAM) introduces challenging requirements for the power amplifier (PA), which consumes the most energy in a wireless handset, and degrades the PA efficiency because of a higher peak-to-average ratio (PAR). In this paper, the impact of using MQAM on the energy dissipation of the PA is examined by capturing the impact of modulation order, PA type, and roll-off factor, along with all corresponding parameters such as PA drain efficiency, the modulation PAR, and the PAR due to the roll-off factor of the transmission pulse. We then investigate different methods for reducing the impact of PAR on PA efficiency. Our results also show that a roll-off factor of 0.42 for a square-root raised cosine (SRRC) pulse can be considered as the optimum choice for wireless communication systems in terms of energy and spectral efficiency. Further, our results show that the linearity and efficiency of class AB PAs can be maintained for very high modulation orders in 5G systems.","Title: Lyapunov Scheduling and Optimization in Network Coded Wireless Multicast Network.\nYear: 2018\n\nAbstract: In this paper, we investigate network coding based scheduling in a single-hop wireless multicast network under queueing stability constraint. Specifically, Lyapunov optimization model is adopted and an optimal network coding scheduling algorithm is derived, which significantly reduces the computational complexity and queue length compared to existing solutions. Moreover, two scheduling policies ba...","Title: IEEE Access Special Section Editorial: Recent Advances in Full-Duplex Radios and Networks.\nYear: 2018\n\nAbstract: With the explosive growth of wireless communications, frequency resources have become scarcer, considering the dramatically increasing demands for higher communication rates. However, by examining the existing duplex modes, e.g., time division duplex (TDD) and frequency division duplex (FDD), it is observed that more than half of the resources are wasted due to the “half-duplex” constraints, as well as the uses of guard zones in the time or frequency domain to avoid interference from neighbor time slots or frequency bands. Therefore, efficiently utilizing the expensive frequency resources to provide high spectrum-efficient communications becomes one of the most important challenges in the design of the next generation wireless communication systems.","Title: Enabling Sustainable Cyber Physical Security Systems through Neuromorphic Computing.\nYear: 2018\n\nAbstract: As the novel paradigm in the field of machine learning, reservoir computing possesses exceptional performance, e.g., energy efficiency, in tasks in which the traditional von Neumann computing systems cannot incorporate. This makes reservoir computing an ideal candidate to enable the sustainable development of cyber-physical systems (CPS). In the realm of CPS, the tight interaction among physical o...","Title: Cognitive relay networks with energy and mutual-information accumulation\nYear: 2018\n\nAbstract: Cognitive radio networks, a.k.a. dynamic spectrum access networks, offer a promising solution to the problems of spectrum scarcity and under-utilization. In this paper, we consider two single-user links: primary and secondary links. To increase secondary user (SU) transmission opportunities and increase primary user (PU) throughput, we consider a cognitive relay network where a SU relays PU packets that are unsuccessfully received at the primary receiver (PR). At the PR side, two protocols are suggested: i) energy accumulation (EA), and ii) mutual-information accumulation (MIA). The average stable throughput of the secondary link is derived under these protocols for a specific throughput selected by the primary link. Results show that EA and MIA can significantly improve the secondary throughput compared with the no accumulation scenario, especially under extreme environment.","Title: High-Rate Ultrasonic Through-Wall Communications Using MIMO-OFDM.\nYear: 2018\n\nAbstract: This paper investigates methods to achieve high-rate data transmission through metallic barriers using ultrasound. Multiple-input-multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM) is employed in conjunction with interference mitigation techniques to reduce throughput-limiting crosstalk. Several crosstalk mitigation strategies are investigated and their theoretical and practica...","Title: Brain-Inspired Wireless Communications: Where Reservoir Computing Meets MIMO-OFDM.\nYear: 2018\n\nAbstract: Reservoir computing (RC) is a class of neuromorphic computing approaches that deals particularly well with time-series prediction tasks. It significantly reduces the training complexity of recurrent neural networks and is also suitable for hardware implementation whereby device physics are utilized in performing data processing. In this paper, the RC concept is applied to detecting a transmitted s...","Title: Multi-Cell Multi-User Massive FD-MIMO: Downlink Precoding and Throughput Analysis.\nYear: 2019\n\nAbstract: In this paper, downlink (DL) precoding and power allocation strategies are identified for a time-division-duplex multi-cell multi-user massive full-dimension MIMO network. Utilizing channel reciprocity, DL channel state information feedback is eliminated and the DL multi-user MIMO precoding is linked to the uplink (UL) direction of arrival (DoA) estimation through the estimation of signal paramete...","Title: Editorial: Booming of Neural Networks and Learning Systems.\nYear: 2019\n\nAbstract: As you open this January issue of the IEEE Transactions on Neural Networks and Learning Systems (TNNLS), I hope everyone enjoyed a great holiday season and is excited for the new year of 2019. I am very delighted and honored to report several key metrics of IEEE TNNLS to the community.","Title: M: N Object matching on multiscale datasets based on MBR combinatorial optimization algorithm and spatial district.\nYear: 2018\n\nAbstract: Object matching is critical for updating, maintaining, integrating, and quality assessing spatial data. However, matching data are often obtained from different sources and have problems of positional discrepancy and different levels of detail. To resolve these problems, this article presents a multiscale polygonal object-matching approach, called the minimum bounding rectangle combinatorial optimization (MBRCO) with spatial district (SD). This method starts with the MBRCO algorithm and its enhancement using the SD to find corresponding MBRs of one-to-one, one-to-many, and many-to-many matching pairs. Then, it aligns the MBRs of the matching pairs to identify object-matching pairs, which are evaluated using a matching criterion to find geometrically corresponding objects. Our approach was experimentally validated using two topographical datasets at 1:2k and 1:10k. The proposed approach outperforms the common two-way area overlap method and another method based on the contextual information and relaxation labeling algorithm. The proposed method achieved accurate aggregation of the many-to-many matching pairs under the positional discrepancy scenario.","Title: Big Data Meet Cyber-Physical Systems: A Panoramic Survey.\nYear: 2018\n\nAbstract: The world is witnessing an unprecedented growth of cyber-physical systems (CPS), which are foreseen to revolutionize our world via creating new services and applications in a variety of sectors, such as environmental monitoring, mobile-health systems, intelligent transportation systems, and so on. The information and communication technology sector is experiencing a significant growth in data traffic, driven by the widespread usage of smartphones, tablets, and video streaming, along with the significant growth of sensors deployments that are anticipated in the near future. It is expected to outstandingly increase the growth rate of raw sensed data. In this paper, we present the CPS taxonomy via providing a broad overview of data collection, storage, access, processing, and analysis. Compared with other survey papers, this is the first panoramic survey on big data for CPS, where our objective is to provide a panoramic summary of different CPS aspects. Furthermore, CPS requires cybersecurity to protect them against malicious attacks and unauthorized intrusion, which become a challenge with the enormous amount of data that are continuously being generated in the network. Thus, we also provide an overview of the different security solutions proposed for CPS big data storage, access, and analytics. We also discuss big data meeting green challenges in the contexts of CPS.","Title: Energy Consumption vs. Bit Rate Analysis Toward Massive MIMO Systems\nYear: 2018\n\nAbstract: In this paper, we provide a comprehensive study and comparison of the impact of both multiple-input multiple-output (MIMO) and massive MIMO techniques, at the base station (BS), on the energy consumption versus bit rate performance of a multi-antenna wireless handset. Both spatial diversity and spatial multiplexing (SM) are examined and compared for both known and unknown channel state information (CSI) at the transmitter. For the diversity case, our results show that for a BS with four or more receive antennas, there is little to be gained in terms of energy efficiency at the wireless handset by having more than one transmit antenna. For the SMcase with conventional MIMO, the bit rate increases linearly with N\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">t</inf>\n at the cost of additional energy consumption at the handset due to the absence of diversity gain. For massive MIMO, however, the excess receive antennas provide a diversity gain in a SM scheme thus allowing a high bit rate without sacrificing energy efficiency at the handset and even with no needs of CSI knowledge.","Title: On the Achievable Transmission Capacity of Secrecy-Based D2D Cellular Networks.\nYear: 2016\n\nAbstract: Device-to-Device (D2D) communication is one of the key technologies to get to very high data rates in future 5G networks through offloading part of the cellular traffic onto D2D networks. While extensive research is targeted on addressing the many challenges D2D brings along in cellular networks, security issues have not gained much attention, especially that the direct connections between proximity devices are more vulnerable to security threats, which in turn deteriorate users' experience. In this paper, we consider a D2D communication overheard by eavesdroppers in an underlay cellular network, where D2D users access a proportion of the spectrum occupied by cellular users. To mitigate the potential security threats, we turn towards a lightweight low-complexity approach by exploiting the physical characteristics of the wireless channels. Using tools from stochastic geometry, we derive the D2D transmission region and the average transmit power that guarantee a minimum secrecy rate and a target outage probability. Results reveal that when offloading less cellular traffic onto D2D links, the large cellular interference can be exploited to protect D2D links from eavesdroppers. On the other hand, with aggressive D2D offloading, D2D users can achieve a much higher secrecy capacity due to significantly reducing the distances between them.","Title: Angle and Delay Estimation for 3-D Massive MIMO/FD-MIMO Systems Based on Parametric Channel Modeling.\nYear: 2017\n\nAbstract: In order to meet the challenge of increasing data-rate demand as well as the form factor limitation of the base station (BS), 3-D massive multiple-input multiple-output (MIMO) technology has been introduced as one of the enabling technologies for fifth generation mobile cellular systems. In 3-D massive MIMO systems, a BS will rely on the uplink sounding signals from mobile stations to figure out t...","Title: A Physical Layer Security Scheme for Mobile Health Cyber-Physical Systems.\nYear: 2018\n\nAbstract: Mobile health (m-Health) is one potential application of cyber-physical systems, where biomedical sensors and mobile devices interact tightly together to transmit medical data to an m-Health server. In this paper, we consider a three-tier hierarchical m-Health system: 1) the sensor network tier capturing vital signals; 2) the mobile computing network tier processing and routing the sensed data to ...","Title: Improving the Coverage and Spectral Efficiency of Millimeter-Wave Cellular Networks Using Device-to-Device Relays.\nYear: 2018\n\nAbstract: The susceptibility of millimeter waveform propagation to blockages limits the coverage of millimeter-wave (mmWave) signals. To overcome blockages, we propose to leverage two-hop device-to-device (D2D) relaying. Using stochastic geometry, we derive expressions for the downlink coverage probability of relay-assisted mmWave cellular networks when the D2D links are implemented in either uplink mmWave ...","Title: Delay-Sensitive Communications Over IR-HARQ: Modulation, Coding Latency, and Reliability\nYear: 2019\n\nAbstract: With the growing popularity of delay-sensitive applications (e.g., real-time conversational video, online gaming, and augmented reality) and future trends toward ultra-reliable low-latency communications such as the tactile Internet, performance analysis of wireless systems under the finite code blocklength constraint becomes extremely important. In this paper, we investigate the maximum achievable throughput of incremental redundancy-hybrid automatic repeat request (IR-HARQ) over the (correlated) Rayleigh fading channel under finite blocklength and delay-violation probability constraints as a function of the modulation scheme. The maximum number of HARQ rounds together with the transport block size specifies the underlying coding latency of the IR-HARQ scheme. A framework, namely the HARQ Markov model (HARQ-MM), is introduced to track the throughput and the probability of error of IR-HARQ over the Rayleigh fading channel as a function of the modulation scheme. The dispersion of parallel additive white Gaussian noise channels with finite input alphabets (e.g., pulse amplitude modulation) is analytically characterized. It is used to identify the state transition probabilities of the underlying HARQ-MM. An algorithm is developed to efficiently compute the steady-state distribution of the HARQ-MM. Extensive performance evaluation is conducted, which shows a good match between the throughput performance characterized by the theoretical framework and that achieved by the practical channel codes.","Title: Green Massive Traffic Offloading for Cyber-Physical Systems over Heterogeneous Cellular Networks\nYear: 2019\n\nAbstract: While the number of things is growing accompanied with an explosive increase in wireless traffic, network providers are facing a set of challenges, especially that the massive number of devices are expected to communicate over the current cellular networks. In an attempt to relieve network congestion and increase throughput, we turn toward cell shrinking and offloading, a key technology in future 5G networks. Using this potential solution, we are mainly targeting two important issues: i) enabling cyber-physical systems (CPS) communications over cellular networks to provide CPS with several benefits such as ubiquitous coverage, global connectivity, reliability and security; and ii) offloading a proportion of CPS traffic to small cells, which in tun increases the throughput of macrocells, and frees more network resources to other users. Using stochastic geometry, we present an analysis on CPS offloading rate and achievable throughput when small cells base stations (SCBSs) are powered by solar energy. The solar energy harvesting allows SCBSs to offset the costs of serving CPS devices. Our results show the potential benefits for both macrocells and small cells in terms of minimum achievable throughput when the CPS offloading rate is high.","Title: Enhancing Communication-Based Train Control Systems Through Train-to-Train Communications\nYear: 2019\n\nAbstract: High reliability and low latency are crucial for urban rail transits. In this paper, we introduce communication strategies for communication-based train control (CBTC) systems using long-term evolution for metro (LTE-M) to improve the reliability and latency. To be specific, the FlashLinQ-based Train-to-Train (T2T) communication schemes are introduced considering both the transmission delay and the packet drop. The quantified resilience is also introduced as a system metric to evaluate the preservation and recovery performance of CBTC systems. First, a novel urban rail transit wireless communication model is established using FlashLinQ-based T2T communications. Then, we introduce a novel cognitive control scheme based on LTE-M with T2T communication to enhance the quality of service and the resilience of multi-train CBTC systems. In the introduced scheme, Q-learning is used to generate optimal control strategies considering both wireless communication parameters adaption and train control parameters. Extensive simulations are conducted and the results show that the resilience of CBTC systems can be enhanced using the introduced scheme. Furthermore, using the introduced scheme, not only the gaps in optimal velocity versus distance curve are smaller, but also the unplanned traction and breaking are reduced as well.","Title: Downlink Resource Allocation in Cell-Free Massive MIMO Systems\nYear: 2019\n\nAbstract: Cell-free Massive Multiple-Input Multiple-Output (MIMO) is introduced as a promising network architecture for the upcoming fifth-generation (5G) wireless communication networks. It enhances user experience and improves the overall system performance by providing huge throughput and coverage probability to all users throughout a system. In this paper, a resource allocation problem is studied for downlink cell-free massive MIMO networks, where each access point (AP) serves a cluster of user equipment (UE). Transmit precoding and power allocation are linked to the underlying max-min scheduling to ensure uniform and excellent service throughout the coverage area. Due to the coupled interference among UEs, the resulting max-min resource allocation optimization problem becomes non-convex. We demonstrate the uplink-downlink duality and propose an iterative algorithm which solves the primal downlink problem efficiently. By utilizing the max-min beam former and taking the channel estimation error into account, we further derive the capacity lower bound of the underlying cell-free massive MIMO network. The performance of the introduced scheme is also investigated through simulations. Numerical results show the efficiency of the introduced algorithm.","Title: Distributive Dynamic Spectrum Access Through Deep Reinforcement Learning: A Reservoir Computing-Based Approach.\nYear: 2019\n\nAbstract: Dynamic spectrum access (DSA) is regarded as an effective and efficient technology to share radio spectrum among different networks. As a secondary user (SU), a DSA device will face two critical problems: 1) avoiding causing harmful interference to primary users (PUs) and 2) conducting effective interference coordination with other SUs. These two problems become even more challenging for a distrib...","Title: QoS-Aware D2D Cellular Networks with Spatial Spectrum Sensing: A Stochastic Geometry View\nYear: 2019\n\nAbstract: Spectrum access and interference management are amongst the most challenging issues in device-to-device (D2D) cellular networks. In order to address these issues, this paper introduces spatial spectrum sensing (SSS) for D2D cellular networks to facilitate cellular spectrum sharing by D2D users while providing a quality of service guarantee for cellular users. In order to assess the performance of ...","Title: Content-Based User Association and MIMO Operation over Cached Cloud-RAN Networks.\nYear: 2019\n\nAbstract: Cloud radio access network (Cloud-RAN) has been introduced to support ever-growing end-users' needs. To reduce the backhaul traffic and aid coordinated multi-point (CoMP) transmission, base station (BS)-level caching technique can be utilized, where popular contents are pre-fetched at each BS. In this paper, multiple-input-multiple-output (MIMO) operation and user association policy are linked to the underlying cache placement strategy to ensure a good trade-off between load balancing and backhaul traffic taking into account the underlying wireless channel and the finite cache capacity at BSs. Due to the coupled interference among mobile stations, the binary nature of the underlying cache placement and user association matrices, the resulting mixed-timescale mixed integer optimization problem is nonconvex and NP-hard. To solve this problem, we decompose the joint optimization problem into a long-term content placement sub-problem and a short-term content delivery sub-problem. A novel iterative algorithm is introduced by leveraging the alternating direction method of multipliers together with a stochastic parallel successive convex approximation-based algorithm. The introduced scheme enables all BSs to update their optimization variables in parallel by solving a sequence of convex subproblems. Simulation evaluation demonstrates the efficiency of our strategy.","Title: An Adaptive Capsule Network For Hyperspectral Remote Sensing Classification\nYear: 2021\n\nAbstract: The capsule network (Caps) is a novel type of neural network that has great potential for the classification of hyperspectral remote sensing. However, the Caps suffers from the issue of gradient vanishing. To solve this problem, a powered activation regularization based adaptive capsule network (PAR-ACaps) was proposed for hyperspectral remote sensing classification, in which an adaptive routing algorithm without iteration was applied to amplify the gradient, and the powered activation regularization method was used to learn the sparser and more discriminative representation. The classification performance of PAR-ACaps was evaluated using two public hyperspectral remote sensing datasets, i.e., the Pavia University (PU) and Salinas (SA) datasets. The average overall classification accuracy (OA) of PAR-ACaps with shallower architecture was measured and compared with those of the benchmarks, including random forest (RF), support vector machine (SVM), 1-dimensional convolutional neural network (1DCNN), two-dimensional convolutional neural network (CNN), three-dimensional convolutional neural network (3DCNN), Caps, and the original adaptive capsule network (ACaps) with comparable network architectures. The OA of PAR-ACaps for PU and SA datasets was 99.51% and 94.52%, respectively, which was higher than those of benchmarks. Moreover, the classification performance of PAR-ACaps with relatively deeper neural architecture (four and six convolutional layers in the feature extraction stage) was also evaluated to demonstrate the effectiveness of gradient amplification. As shown in the experimental results, the classification performance of PAR-ACaps with relatively deeper neural architecture for PU and SA datasets was also superior to 1DCNN, CNN, 3DCNN, Caps, and ACaps with comparable neural architectures. Additionally, the training time consumed by PAR-ACaps was significantly lower than that of Caps. The proposed PAR-ACaps is, therefore, recommended as an effective alternative for hyperspectral remote sensing classification.","Title: Cooperative Caching in HetNets With Mutual Information Accumulation\nYear: 2021\n\nAbstract: Caching is a promising technique in the next generation cellular network, reducing backhaul traffic while improving network efficiency. In this letter, we introduce a cache-enabled small base station cooperative transmission scheme while considering the macro base station (MBS) silence and mutual information accumulation (MIA). A tractable analytical framework for characterizing the successful transmission probability (STP) of the introduced scheme is described. The STP is maximized by optimizing the caching placement policy based on a constrained cross entropy optimization algorithm. Simulation results demonstrate that the proposed SBS cooperative transmission with MBS silence and MIA achieves higher STP than other compared schemes.","Title: Interference Alignment Meets Multi-Cell Multi-User Massive FD-MIMO Systems in DoA-Based Precoding\nYear: 2021\n\nAbstract: In this paper, a downlink (DL) precoding scheme is introduced for time-division-duplex (TDD) multi-cell multi-user 3D massive MIMO/full-dimension MIMO (FD-MIMO) systems. A pre-beamformer based on uplink direction-of-arrival (DoA) is incorporated with interference alignment (IA) scheme to provide more degrees of freedom for each cell. We analyze the feasible conditions of applying IA schemes and pr...","Title: Adversarial Classification of the Attacks on Smart Grids Using Game Theory and Deep Learning\nYear: 2021\n\nAbstract: ABSTRACTSmart grids are vulnerable to cyber-attacks. This paper proposes a game-theoretic approach to evaluate the variations caused by an attacker on the power measurements. Adversaries can gain financial benefits through the manipulation of the meters of smart grids. On the other hand, there is a defender that tries to maintain the accuracy of the meters. A zero-sum game is used to model the interactions between the attacker and defender. In this paper, two different defenders are used and the effectiveness of each defender in different scenarios is evaluated. Multi-layer perceptrons (MLPs) and traditional state estimators are the two defenders that are studied in this paper. The utility of the defender is also investigated in adversary-aware and adversary-unaware situations. Our simulations suggest that the utility which is gained by the adversary drops significantly when the MLP is used as the defender. It will be shown that the utility of the defender is variant in different scenarios, based on the defender that is being used. In the end, we will show that this zero-sum game does not yield a pure strategy, and the mixed strategy of the game is calculated.","Title: Trade-Offs in Reliability, Latency, and Energy for Random Network Coding-Enabled Networks\nYear: 2021\n\nAbstract: In random network coding (RNC)-enabled networks, a sufficient number of linearly independent encoded packets, i.e., generations, is guaranteed at the cost of high latency and energy consumption at the transmitter. This letter aims to reduce the weighted sum of latency and energy while guaranteeing a targeted successful transmission probability, which is defined as the probability that the RNC-enabled network has sufficient generations when the transmitter receives a required number of acknowledgements (ACKs) feedback. An analytical framework and a deep learning-based method are developed. Results show that the latency and energy consumption are reduced by jointly optimizing the required number of ACKs and the transmit power at the transmitter.","Title: Multiagent Reinforcement Learning Meets Random Access in Massive Cellular Internet of Things\nYear: 2021\n\nAbstract: Internet of Things (IoT) has attracted considerable attention in recent years due to its potential of interconnecting a large number of heterogeneous wireless devices. However, it is usually challenging to provide reliable and efficient random access control when massive IoT devices are trying to access the network simultaneously. In this article, we investigate methods to introduce intelligent ra...","Title: Learning to Equalize OTFS\nYear: 2022\n\nAbstract: Orthogonal Time Frequency Space (OTFS) is a novel framework that processes modulation symbols via a time-independent channel characterized by the delay-Doppler domain. The conventional waveform, orthogonal frequency division multiplexing (OFDM), requires tracking frequency selective fading channels over the time, whereas OTFS benefits from full time-frequency diversity by leveraging appropriate equalization techniques. In this paper, we consider a neural network-based supervised learning framework for OTFS equalization. Learning of the introduced neural network is conducted in each OTFS frame fulfilling an online learning framework: the training and testing datasets are within the same OTFS-frame over the air. Utilizing reservoir computing, a special recurrent neural network, the resulting one-shot online learning is sufficiently flexible to cope with channel variations among different OTFS frames (e.g., due to the link/rank adaptation and user scheduling in cellular networks). The proposed method does not require explicit channel state information (CSI) and simulation results demonstrate a lower bit error rate (BER) than conventional equalization methods in the low signal-to-noise (SNR) regime under large Doppler spreads. When compared with its neural network-based counterparts for OFDM, the introduced approach for OTFS will lead to a better tradeoff between the processing complexity and the equalization performance.","Title: Computing over Space-Air-Ground Integrated Networks: Challenges and Opportunities\nYear: 2021\n\nAbstract: Space-air-ground integrated networks (SAGINs) have gained significant attention and become a promising architecture for ubiquitous connectivity for 5G-Advanced and 6G, enabling the integration of satellite networks, aerial networks, and terrestrial networks. This integration brings tremendous communication benefits, such as non-terrestrial networks, seamless global coverage, high flexibility, and augmented system capacity. Meanwhile, computing capability becomes an indispensable part of the SAGIN ecosystem. In SAGINs, limited and unbalanced computation and communication resources of different network segments make it challenging to provide strict quality-of-service (QoS) guarantees for specific traffic (e.g., delay-sensitive traffic and outage-sensitive traffic). To fully utilize available system resources in SAGINs, cooperative computing among different network segments is a promising technology. This article presents the fundamentals and applications of computing over SAGINs by introducing the system architecture and explaining the potential technical issues related to cooperative computing. Furthermore, the potential for cooperative computing over SAGINs is showcased with a preliminary performance evaluation. Finally, future research opportunities are discussed.","Title: Deep Learning-Assisted Energy-Efficient Task Offloading in Vehicular Edge Computing Systems\nYear: 2021\n\nAbstract: In this paper, we study an energy-efficient computation offloading for vehicular edge computing systems, where multiple roadside units assist vehicular users to offload computation tasks to edge servers. Our goal is to minimize the users’ energy consumption by optimizing user association, data partition, transmit power, and computation resources, subject to the constraints of partial tasks offload...","Title: RC-Struct: A Structure-Based Neural Network Approach for MIMO-OFDM Detection\nYear: 2022\n\nAbstract: In this paper, we introduce a structure-based neural network architecture, namely RC-Struct, for MIMO-OFDM symbol detection. The RC-Struct exploits the temporal structure of the MIMO-OFDM signals through reservoir computing (RC). A binary classifier leverages the repetitive constellation structure in the system to perform multi-class detection. The incorporation of RC allows the RC-Struct to be learned in a purely online fashion with extremely limited pilot symbols in each OFDM subframe. The binary classifier enables the efficient utilization of the precious online training symbols and allows an easy extension to high-order modulations without a substantial increase in complexity. Experiments show that the introduced RC-Struct outperforms both the conventional model-based symbol detection approaches and the state-of-the-art learning-based strategies in terms of bit error rate (BER). The advantages of RC-Struct over existing methods become more significant when rank and link adaptation are adopted. The introduced RC-Struct sheds light on combining communication domain knowledge and learning-based receive processing for 5G/5G-Advanced and Beyond.","Title: A Cost-Efficient Digital ESN Architecture on FPGA for OFDM Symbol Detection\nYear: 2021\n\nAbstract: AbstractThe echo state network (ESN) is a recently developed machine-learning paradigm whose processing capabilities rely on the dynamical behavior of recurrent neural networks. Its performance outperforms traditional recurrent neural networks in nonlinear system identification and temporal information processing applications. We design and implement a cost-efficient ESN architecture on field-programmable gate array (FPGA) that explores the full capacity of digital signal processor blocks on low-cost and low-power FPGA hardware. Specifically, our scalable ESN architecture on FPGA exploits Xilinx DSP48E1 units to cut down the need of configurable logic blocks. The proposed architecture includes a linear combination processor with negligible deployment of configurable logic blocks and a high-accuracy nonlinear function approximator. Our work is verified with the prediction task on the classical NARMA dataset and a symbol detection task for orthogonal frequency division multiplexing systems using a wireless communication testbed built on a software-defined radio platform. Experiments and performance measurement show that the new ESN architecture is capable of processing real-world data efficiently for low-cost and low-power applications.","Title: Optimizing Number, Placement, and Backhaul Connectivity of Multi-UAV Networks\nYear: 2022\n\nAbstract: Multi unmanned aerial vehicle (UAV) network is a promising solution to providing wireless coverage to ground users in challenging rural areas (such as Internet of Things (IoT) devices in farmlands), where the traditional cellular networks are sparse or unavailable. A key challenge in such networks is the 3-D placement of all UAV base stations (BSs) such that the formed multi-UAV network: 1) utilizes a minimum number of UAVs while ensuring—2) backhaul connectivity directly (or via other UAVs) to the nearby terrestrial BS; and 3) wireless coverage to all ground users in the area of operation. This joint backhaul-and-coverage-aware drone deployment (BoaRD) problem is largely unaddressed in the literature and, thus, is the focus of this article. We first formulate the BoaRD problem as integer linear programming (ILP). However, the problem is NP-hard and, therefore, we propose a low complexity algorithm with a provable performance guarantee to solve the problem efficiently. Our simulation study shows that the Proposed algorithm performs very close to that of the Optimal algorithm (solved using ILP solver) for smaller scenarios, where the area size and the number of users are relatively small. For larger scenarios, where the area size and the number of users are relatively large, the proposed algorithm greatly outperforms the baseline approaches—Backhaul-aware Greedy and random algorithm, respectively, by up to 17% and 95% in utilizing fewer UAVs while ensuring 100% ground-user coverage and backhaul connectivity for all deployed UAVs across all considered simulation setting.","Title: UAV Swarm-Enabled Aerial Reconfigurable Intelligent Surface (SARIS)\nYear: 2021\n\nAbstract: Reconfigurable intelligent surface (RIS) offers tremendous spectrum and energy efficiency in wireless networks by adjusting the amplitudes and/or phases of passive reflecting elements to optimize signal reflection. With the agility and mobility of unmanned aerial vehicles (UAVs), RIS can be mounted on UAVs to enable three-dimensional signal reflection. Compared to the conventional terrestrial RIS ...","Title: A Hybrid FPGA-ASIC Delayed Feedback Reservoir System to Enable Spectrum Sensing/Sharing for Low Power IoT Devices ICCAD Special Session Paper\nYear: 2021\n\nAbstract: The delayed feedback reservoir (DFR) network is a delay-dynamic architecture that incorporates time in its training and inference. This quality enables DFR networks to proficiently model time series in a scalable architecture with only one nonlinear neuron. Previous studies have highlighted the accuracy and energy efficiency of DFR networks in ASIC implementations; however, these approaches are li...","Title: Resource Allocation for D2D Cellular Networks With QoS Constraints: A DC Programming- Based Approach\nYear: 2022\n\nAbstract: Device-to-device (D2D) communications provide efficient ways to increase spectrum utilization ratio with reduced power consumption for proximity wireless applications. In this paper, we investigate resource allocation strategies for D2D communications underlaying cellular networks. To be specific, we study the centralized resource allocation algorithm for controlling transmit powers of the underlying D2D pairs in order to maximize the weighted sum-rate while guaranteeing the quality of service (QoS) requirements for both D2D pairs and cellular users (CUs). A novel DC (difference of convex function) programming-based method, called alternative DC (ADC) programming, is introduced to effectively solve this complicated resource allocation problem. Through updating each D2D pair's power alternatively, the QoS requirement for each D2D pair can be solvable and incorporated systematically to the introduced ADC programming framework. The simulation results show that the introduced ADC programming achieves the highest weighted sum-rate compared to the state-of-the-art methods while ensuring that the QoS of each D2D pair and CU are satisfied.","Title: Reservoir Computing Meets Extreme Learning Machine in Real-Time MIMO-OFDM Receive Processing\nYear: 2022\n\nAbstract: In this paper, we consider a real-time deep learning-based symbol detection approach for MIMO-OFDM systems. To exploit the temporal correlation of the wireless channel and the time-frequency structure of OFDM signals, a recurrent neural network (RNN) with deep feedforward output layers is introduced, where the recurrent layers and feedforward output layers are designed to process time-domain and frequency-domain information respectively. Reservoir computing (RC), a special type of RNN, and extreme learning machine (ELM), a special type of feedforward neural network, are chosen as the corresponding building blocks to facilitate over-the-air training. An online training loss objective is introduced to recursively update the neural weights in real-time. We believe this is the first work in the literature to realize real-time machine learning for MIMO-OFDM symbol detection, i.e., conducting NN-based symbol detection on an OFDM symbol basis. We demonstrate that (1) the \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">IEEE</i>\n standardized WiFi training sequence can be directly applied as the real-time training sequence (2) the symbol detection performance can be further improved by using our theoretically derived pilot pattern. Evaluation results show that our RC-ELM-based symbol detection method outperforms traditional model-based techniques as well as state-of-the-art learning-based approaches in highly dynamic channel environments for real-time symbol detection."],"string":"[\n \"Title: On Coding Over Finite \\\"Packets\\\" In Wireless Communication Systems\\nYear: 2013\\n\\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In light of this challenge, this paper investigates the throughput performance of a wireless communication system under channel coding over finite \\\"packets.\\\" When we apply coding over multiple \\\"packets,\\\" the underlying wireless channel can be effectively modeled as a finite-state Markov process. By linking the characteristics of the underlying physical channel to the parameters of the Markov process, we are able to derive the channel dispersion of the corresponding system. The channel dispersion is then used to assess the coding performance of various communication strategies. It is interesting to find that when there is a constraint on the total blocklength, coding over large \\\"packets\\\" will give better performance than that of coding over small \\\"packets.\\\"\",\n \"Title: Downlink MIMO in LTE-advanced: SU-MIMO vs. MU-MIMO.\\nYear: 2012\\n\\nAbstract: Single-user multi-antenna technologies are well upported in current standard specifications like LTE Release 8/9. Further development of the specification (LTE-Advanced) is expected to conform to the requirements for IMT-Advanced systems. One of the key enabling features of LTE-Advanced to meet IMT-Advanced downlink performance requirements is multi-user MIMO, where a transmitter serves multiple u...\",\n \"Title: Adaptive scheduling for multicasting hard deadline constrained prioritized data via network coding.\\nYear: 2012\\n\\nAbstract: Network coding offers a promising platform for multicast transmission by approaching its min-cut capacity. However, pushing the network throughput toward this upper bound comes with a sacrifice in delivery delay due to the decoding procedure that requires performing batch of coded packets. Further, in some transmission scenarios where the receivers experience deep fading or unable to collect a full set of the transmitted data, no useful information is recovered. The effect is more severe in the networks where the transmitted information has priority structure with hard deadline constraint due to the limited delivery time and data interdependencies. In this paper, we consider single-hop wireless networks where the transmitter wishes to multicast hard deadline constrained prioritized data to many receivers over lossy channels. We first study the network performance of a variety of transmission techniques, depending on how the transmitter schedules transmission in each time slot. We then propose an adaptive encoding and scheduling technique to maximize the network throughput. To find the optimal transmission scheduling at the presence of the network dynamics, we cast the problem in the framework of Markov Decision Processes (MDP) and use backward induction method to find an optimal solution. We further propose simulation-based algorithm and greedy scheduling technique that obtain high performance with much lower time complexity. Both analytical and simulation results have been provided to corroborate the effectiveness of the proposed techniques.\",\n \"Title: Distributed optimal power control for multicarrier cognitive systems\\nYear: 2012\\n\\nAbstract: In this paper, the power optimization of the multicarrier cognitive system underlying the primary network is investigated. We consider the interference coupled cognitive network under individual secondary user's power constraint and primary user's rate constraint. A multicarrier discrete distributed (MCDD) algorithm based on Gibbs sampler is proposed. Although the problem is nonconcave, MCDD is proved to converge to the global optimal solution. To reduce the computational complexity and convergence time, the Gibbs sampler based Lagrangian algorithm (GSLA) is proposed to get a near optimal solution. We also provide simulation results to show the effectiveness of the proposed algorithms.\",\n \"Title: Resource Allocation and Quality of Service Evaluation for Wireless Communication Systems Using Fluid Models\\nYear: 2007\\n\\nAbstract: Wireless systems offer a unique mixture of connectivity, flexibility, and freedom. It is therefore not surprising that wireless technology is being embraced with increasing vigor. For real-time applications, user satisfaction is closely linked to quantities such as queue length, packet loss probability, and delay. System performance is therefore related to, not only Shannon capacity, but also quality of service (QoS) requirements. This work studies the problem of resource allocation in the context of stringent QoS constraints. The joint impact of spectral bandwidth, power, and code rate is considered. Analytical expressions for the probability of buffer overflow, its associated exponential decay rate, and the effective capacity are obtained. Fundamental performance limits for Markov wireless channel models are identified. It is found that, even with an unlimited power and spectral bandwidth budget, only a finite arrival rate can be supported for a QoS constraint defined in terms of exponential decay rate\",\n \"Title: Adaptive resource allocation for heterogeneous traffic over heterogeneous relay networks\\nYear: 2013\\n\\nAbstract: Future wireless communication networks will face the dual challenge of supporting large traffic volumes while providing reliable service for heterogeneous traffic types. In order to meet the ever increasing traffic demand, heterogeneous relay network is introduced as an enabling technology for the fourth generation (4G) mobile broadband networks. In this paper, we will investigate optimal power and subcarrier allocation strategies for heterogeneous relay networks under statistical quality of service (QoS) constraints. To be specific, we will characterize the effective capacity of a wireless relay system under QoS constraints. The properties of the optimal resource and subcarrier allocation strategies for delay-sensitive traffic over heterogeneous relay networks will also be identified. Two low complexity resource and subcarrier allocation algorithms will be introduced to optimize the effective capacity. Our results suggest that the optimal power and subcarrier allocation strategies depend heavily on the underlying QoS constraint. In the low signal-to-interference-plus-noise (SINR) regime, when there is no QoS constraint, both base stations and relay nodes will allocate all the transmit power to the best subcarrier. However, as the QoS requirement becomes more stringent, both base stations and relay nodes will spread their transmit power over multiple subcarriers.\",\n \"Title: Quality of Service Analysis for Wireless User-Cooperation Networks\\nYear: 2007\\n\\nAbstract: A wireless communication system in which multiple users cooperate to transmit information to a common destination is considered. The traffic generated by the users is subject to a stringent quality of service requirement, which is defined in terms of the asymptotic decay-rate of buffer occupancy. The performance of this communication system is analyzed, and the corresponding achievable rate-region for the two-user scenario is identified. A simple user-cooperation scheme that improves performance is proposed. This cooperative scheme is shown to significantly enlarge the achievable rate-region of the service constrained communication system, provided that the quality of the wireless link between cooperating users is better than the individual connections from the users to the intended destination. Numerical results further indicate that the gains of cooperative strategies can be substantial. This suggests that cooperation allows for a fair distribution of the wireless resources among active users.\",\n \"Title: User Cooperation in the Absence of Phase Information at the Transmitters\\nYear: 2008\\n\\nAbstract: In this paper, a multiuser communication system in which wireless users cooperate to transmit information to a base station is considered. The proposed scheme can significantly enlarge the achievable rate region, provided that the wireless connections between pairs of cooperating users are stronger than the connection from every user to the base station. The gains in transmission rate remain substantial even when the channel phase information is only available at the receivers, not at the transmitters. In the proposed scheme, a transmission period is divided into two time intervals. During the first time interval, wireless users send data to the base station and to the neighboring users simultaneously using a broadcast channel paradigm. During the second time interval, the users cooperate to transmit information to the base station. The achievable rate region corresponding to this paradigm is characterized under a random phase channel model for a two-user system. Results are then generalized to a multiple-user scenario. For fixed system parameters, the achievable rate region is strictly larger than that of the traditional multiple-access channel, thereby allowing a fair distribution of the wireless resources among users. Numerical analysis suggests that cooperating with a single partner is enough to achieve most of the benefits associated with cooperation.\",\n \"Title: Cooperative Communication Technologies For Lte-Advanced\\nYear: 2010\\n\\nAbstract: The LTE-Advanced (LTE-A) system is currently under development to allow for significantly higher spectral efficiency and data throughput than LTE systems. In a wireless system based on orthogonal frequency division multiplexing (OFDM) with frequency reuse factor one such as LTE, the achievable cell spectral efficiency is often limited by the inter-cell interference or coverage shortage of base stations. Hence in LTEA, coordinated multi-point (CoMP) transmission/reception (a.k.a. multi-cell MIMO or base station cooperation) and relaying technologies are being introduced to clear these major performance hurdles. In this paper, overall picture of cooperative communication technologies being discussed in LTE-A systems including CoMP and relayingis presented, together with considerations on system design.\",\n \"Title: Link adaptation for energy-efficient uplink coordinated multi-point receptions.\\nYear: 2011\\n\\nAbstract: We investigate link adaptation methods for energy-efficient uplink coordinated multi-point receptions. A system model for practical cellular networks is introduced, in which only a subset of base stations participates in cooperative link adaptation and cooperative decoding for uplink transmissions. To cope with channel-state-information (CSI) mismatch incurred from the system model, link adaptation controllers implementing rate back-off from the maximum achievable rate calculated with the mismatched CSI is introduced. From analytical and simulation results, it is concluded that under a certain condition, the rate back-off does not help to improve energy efficiency, where, for example, the condition holds when the CSI errors are modeled as additive Gaussian random variables. Furthermore, energy efficiency of multi-user spatial-division-multiple-access uplink transmissions is studied in isolated cooperative cellular networks. In this scenario, an analytical expression for the optimal link adaptation achieving maximum energy efficiency is obtained.\",\n \"Title: Distributed heterogeneous traffic delivery over heterogeneous wireless networks\\nYear: 2012\\n\\nAbstract: In order to meet the spectacular growth in mobile data traffic, one of the technologies is heterogeneous network, where small cells overlaid by large cells can be deployed. With such, base stations (BSs) can be of heterogeneous characteristics in bandwidth, capacity, load, backhaul delay, etc. Meanwhile, the traffic of diverse applications of a mobile station (MS) can be of heterogeneous quality of service (QoS) in rate, delay, etc. This paper proposes a framework to solve the problem of how to efficiently deliver heterogeneous traffic with heterogeneous QoS requirements in heterogeneous networks. We formulate optimization problems, to associate traffic flows with different QoS requirements of an MS to multiple BSs, so that QoS requirements can be satisfied, where the BS backhaul conditions are taken into account. Algorithms are proposed based on analysis. Numerical results show our framework can provide more efficiency in delay stringent and delay astringent traffic delivery.\",\n \"Title: New leakage-based iterative coordinated beam-forming for multi-user MIMO in LTE-Advanced\\nYear: 2012\\n\\nAbstract: In this paper, we investigate a typical LTE-Advanced multi-user MIMO system where mobile stations (MSs) feedback limited channel state information using codebook based approaches. A joint optimization of multi-user scheduling, linear transmit beam-forming, and receive combining is conducted at the base station to combat the intra-cell interference created by multi-user MIMO operation. Low complexity coordinated beam-forming schemes based on proportional-fair metric is proposed for jointly designing the beam-forming and receive combining vectors. Feedback schemes complied with LTE-Advanced specification is also introduced for the proposed coordinated beam-forming scheme. System level evaluation is conducted to show that the proposed coordinated beam-forming can help improving the performance of LTE-Advanced systems significantly.\",\n \"Title: Automated Residential Demand Response: Algorithmic Implications of Pricing Models\\nYear: 2012\\n\\nAbstract: Smart energy management is an important problem in Smart Grid network, and demand response (DR) is one of the key enabling technologies. If each home uses automated demand response which would opportunistically schedule devices that are flexible to run at any time in a large time window, towards the slots with lower electricity prices, peaks at these slots may happen. We denote such peaks as rebound peaks. We address the potential rebound peak problems of automated DR algorithms, and provide possible solutions. We illustrate why a rebound peak is possible via the insights we obtain from the optimal automated DR algorithm. We show that if the utility electricity supply cost is assumed to be a homogeneous function in the energy consumption over a certain time span, a system of multiple homes and utility company has the lowest total electricity supply cost if the electricity consumption from all the homes is flat over the time span. We study multiple approaches to reduce the rebound peak, and accordingly propose algorithms for DR at each home. Effectiveness of the approaches is verified by numerical results.\",\n \"Title: Optimal fusion scheme in wireless sensor networks under sum-rate capacity constraint\\nYear: 2010\\n\\nAbstract: In this paper, we investigate optimal fusion schemes for decentralized detection problems in which a network of wireless sensors provides relevant information about the state of nature to a fusion center. Upon independent reception of the signal, each sensor performs distributed binary detection and sends the decision as well as the reliability of the decision to the fusion center. The capacity region of the corresponding multi-access channel (MAC) from wireless sensors to the fusion center is identified and the sum-rate capacity is characterized. Further-more, it can be shown that when the number of wireless sensors is big enough, the sum-rate capacity of the corresponding MAC channel converges to a constant due to ¿channel-hardening¿. Based on this result, we analyze the performance of quantizing the reliability of the decentralized decision under the sum-rate capacity constraint. The corresponding optimal fusion scheme is derived and the analysis is conducted under the low signal-to-noise (SINR) regime to better reflect the reality.\",\n \"Title: Capacity Of Multicarrier Multilayer Broadcast And Unicast Hybrid Cellular System With Independent Channel Coding Over Subcarriers\\nYear: 2011\\n\\nAbstract: In this paper, we discuss the hybrid capacity region of a generic multicarrier multilayer broadcast and unicast cellular system with independent channel coding over subcarriers. In particular, we analytically derive the capacity region and provide conditions to achieve its boundary. The simulation results show that the hybrid capacity regions are considerably higher than those of the traditional time division multiplexing scheme.\",\n \"Title: Spectrum Optimization For Ofdma Based Hybrid Wireless Networks\\nYear: 2011\\n\\nAbstract: This paper proposes a new cooperative resource allocation scheme for OFDMA based hybrid network. Different from the traditional cognitive radio networks that aim to utilize the spectrum holes in an uncoordinated way, we study the joint resource allocation for both the primary users and the secondary users. Results show that our approach can achieve higher spectral efficiency and provide satisfactory admission control and QoS for all users.\",\n \"Title: A New Cooperative Spectrum Sensing Scheme for Cognitive Ad-Hoc Networks.\\nYear: 2011\\n\\nAbstract: As the radio spectrum is becoming more and more crowded, cognitive radio has recently become a hot research topic to improve the spectrum utilization efficiency. It is well known that the success of cognitive radio depends heavily on fast and efficient spectrum sensing that is very difficult in practice. Toward this end, this paper introduces a new guard-resident cooperative spectrum sensing scheme for a cognitive ad-hoc network. In particular, we classify cognitive nodes as either or based on the spectrum neighbor decision and distributed boundary search. The guard nodes sense the spectrum and then inform the resident nodes that are greatly relieved from spectrum sensing about the radio environmental changes. The analysis and simulation results show that the proposed algorithm can significantly reduce the total spectrum sensing load without sacrificing the sensing accuracy.\",\n \"Title: Low complexity direction of arrival (DoA) estimation for 2D massive MIMO systems\\nYear: 2012\\n\\nAbstract: Mobile data traffic is expected to almost double every year from 2012 to 2016. In order to address the challenge, “massive MIMO” has been proposed as one of the enabling technologies to significantly increase the spectral-efficiency of a wireless system. In “massive MIMO” systems, a base station will rely on the uplink sounding signals from mobile stations to figure out the channel knowledge to perform MIMO beam-forming. Accordingly, direction-of-arrival estimation at the base station becomes crucial for “massive MIMO” systems to realize the predicted capacity gains. In this paper, we study DoA estimation for two-dimensional (2D) “massive MIMO” systems in mobile wireless systems. To be specific, we derive the Cramer-Rao lower bound for 2D “massive MIMO” systems and introduce a low complexity direction-of-arrival estimation algorithm to jointly estimate elevation and azimuth angles of the arrived signals based on unitary transformation. Results suggest that the dimension of the antenna array at the base station plays an important role in the estimation performance. It is also found that azimuth estimation is more vulnerable compared to elevation estimation. These insights will be useful for designing practical “massive MIMO” systems in future mobile wireless communications.\",\n \"Title: Cooperative Routing for Wireless Networks using Mutual-Information Accumulation\\nYear: 2009\\n\\nAbstract: Cooperation between the nodes of wireless multihop networks can increase\\ncommunication reliability, reduce energy consumption, and decrease latency. The\\npossible improvements are even greater when nodes perform mutual information\\naccumulation using rateless codes. In this paper, we investigate routing\\nproblems in such networks. Given a network, a source, and a destination, our\\nobjective is to minimize end-to-end transmission delay under energy and\\nbandwidth constraints. We provide an algorithm that determines which nodes\\nshould participate in forwarding the message and what resources (time, energy,\\nbandwidth) should be allocated to each.\\n Our approach factors into two sub-problems, each of which can be solved\\nefficiently. For any transmission order we show that solving for the optimum\\nresource allocation can be formulated as a linear programming problem. We then\\nshow that the transmission order can be improved systematically by swapping\\nnodes based on the solution of the linear program. Solving a sequence of linear\\nprograms leads to a locally optimal solution in a very efficient manner. In\\ncomparison to the proposed cooperative routing solution, it is observed that\\nconventional shortest path multihop routing typically incurs additional delays\\nand energy expenditures on the order of 70%.\\n Our first algorithm is centralized, assuming that routing computations can be\\ndone at a central processor with full access to channel state information for\\nthe entire system. We also design two distributed routing algorithms that\\nrequire only local channel state information. We provide simulations showing\\nthat for the same networks the distributed algorithms find routes that are only\\nabout two to five percent less efficient than the centralized algorithm.\",\n \"Title: Secure network-coded wireless multicast for delay-sensitive data\\nYear: 2012\\n\\nAbstract: Wireless multicast for delay-sensitive data is challenging because different receivers may experience different packet losses. Network coding offers significant advantages over the traditional Automatic Repeat-reQuest (ARQ) protocols in that it mitigates the need for retransmission and has the potential to approach the min-cut capacity. Network-coded multicast would be, however, vulnerable to false packet injection attacks, in which the adversary injects bogus packets to prevent receivers from correctly decoding the original data. Without a right defense in place, even a single bogus packet can completely change the decoding outcome. Existing solutions either incur high computation cost or cannot withstand high packet loss. In this paper, we propose a novel scheme to defend against false packet injection attacks on network-coded multicast for delay-sensitive data. Specifically, we propose an efficient authentication mechanism based on null space properties of coded packets, aiming to enable receivers to detect any bogus packets with high probability. We further design an adaptive scheduling algorithm based on Markov Decision Processes (MDP) to maximize the number of authenticated packets that can be received within a given time constraint. Both analytical and simulation results have been provided to demonstrate the efficacy and efficiency of our proposed scheme.\",\n \"Title: Proportional fair scheduling for multi-cell multi-user MIMO systems\\nYear: 2010\\n\\nAbstract: In this paper, a multi-cell multi-user MIMO scheme with advanced user pairing and scheduling algorithm is proposed to effectively explore multi-user diversity and to combat both intra-cell and inter-cell interference in the downlink of wireless communication systems. The optimality of the proposed user paring and scheduling algorithm is shown under generalized proportional fair metrics. System-level simulations are conducted to verify the performance of the proposed scheme with the agreed LTE-Advanced (LTE-A) system parameters. The results suggest the proposed scheme is a promising candidate for improving both the cell-edge user throughput and average cell throughput, and furthermore for fulfilling the IMT-Advanced (IMT-A) requirements.\",\n \"Title: Performance analysis of wireless hybrid-ARQ systems with delay-sensitive traffic\\nYear: 2010\\n\\nAbstract: The design of wireless communication schemes tailored to real-time traffic requires an analysis framework that goes beyond the traditional criterion of data throughput. This work considers an approach that relates physical system parameters to the queueing performance of wireless links. The potential benefits of multi-rate techniques such as hybrid-ARQ are assessed in the context of delay-sensitive traffic using large deviations. A continuous-time Markov channel model is employed to partition the instantaneous data-rate received at the destination into a finite number of states, each representing a mode of operation of the hybrid-ARQ scheme. The proposed methodology accounts for the correlation of the wireless channel across time, which is computed in terms of level-crossing rates. The tail asymptote governing buffer overflow probabilities at the transmitter is then used to provide a measure of overall performance. This approach leads to a characterization of the effective capacity of the system which, in turn, is applied to quantify the performance advantages of hybrid-ARQ over traditional schemes.\",\n \"Title: Secure Wireless Multicast for Delay-Sensitive Data via Network Coding\\nYear: 2013\\n\\nAbstract: Wireless multicast for delay-sensitive data is challenging because of the heterogeneity effect where each receiver may experience different packet losses. Fortunately, network coding, a new advanced routing protocol, offers significant advantages over the traditional Automatic Repeat reQuest (ARQ) protocols in that it mitigates the need for retransmission and has the potential to approach the min-cut capacity. Network-coded multicast would be, however, vulnerable to false packet injection attacks, in which the adversary injects bogus packets to prevent receivers from correctly decoding the original data. Without a right defense in place, even a single bogus packet can completely change the decoding outcome. Existing solutions either incur high computation cost or cannot withstand high packet loss. In this paper, we propose a novel scheme to defend against false packet injection attacks on network-coded multicast for delay-sensitive data. Specifically, we propose an efficient authentication mechanism based on null space properties of coded packets, aiming to enable receivers to detect any bogus packets with high probability. We further design an adaptive scheduling algorithm based on the Markov Decision Processes (MDP) to maximize the number of authenticated packets received within a given time constraint. Both analytical and simulation results have been provided to demonstrate the efficacy and efficiency of our proposed scheme.\",\n \"Title: Routing In Cooperative Wireless Networks With Mutual-Information Accumulation\\nYear: 2008\\n\\nAbstract: Cooperation between the nodes of wireless multi-hop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual-information accumulation, e.g., by using rateless codes. In this paper, we investigate routing problems in such networks. Given a network, a source and a destination, our objective is to minimize end-to-end transmission delay under a sum energy constraint. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any node decoding order we show that solving for the optimum resource allocation can be formulated as a linear problem. We then show that the decoding order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear program leads to a locally optimum solution in a very efficient manner. In comparison to the cooperative routings, it is observed that conventional shortest-path multihop routings incur additional delays and energy expenditures on the order of 70%. Since this initial solution is centralized, requiring full channel state information, we exploit the insights to design two distributed routing algorithms that require only local channel state information. We provide simulations showing that in the same networks the distributed algorithms find routes that are only about 2 - 5% less efficient than the centralized solution.\",\n \"Title: Energy-efficient power allocation for delay-sensitive traffic over wireless systems\\nYear: 2012\\n\\nAbstract: Energy-efficient communication becomes increasingly important for wireless communication systems partially due to the fact that the improvement in battery technology is much slower than the increase for processing power and energy consumption of electronic devices. On the other hand, the telecommunication industry predicts that the mobile data traffic will double almost every year for the next five years with more than two thirds of the future traffic being video. Since many of the video applications are delay-sensitive, it is extremely important to consider energy-efficient design for delay-sensitive traffics over wireless systems. This paper addresses resource allocation for maximizing the energy-efficiency of a wireless link under statistical quality of service (QoS) constraints. In the energy-efficiency analysis, both circuit power and transmission power of a communication system are taken into account. The joint impact of statistical QoS constraints, transmission power, and spectral bandwidth are considered. The unique globally optimal power allocation scheme is characterized. The intuition of the optimal strategy is obtained by looking at both low signal-to-noise ratio (SNR) regime and high SNR regime.\",\n \"Title: Energy-efficient scheduling for downlink multi-user MIMO\\nYear: 2012\\n\\nAbstract: Multi-user MIMO is the enabling technology for LTE-Advanced systems to meet IMT-Advanced targets. The gain of multi-user MIMO is achieved partially through advanced user-grouping, user-scheduling, and precoding. Traditionally, multiuser MIMO scheduling focuses solely on spectral-efficiency [1]. That is, the scheduler will strike to balance the cell-edge user spectral-efficiency as well as the cell-average spectral-efficiency. Similar to spectral-efficiency, energy-efficiency is becoming increasingly important for wireless communications. The energy efficiency is measured by a classical measure, “throughput per Joule”, while both RF transmit power and device electronic circuit power consumptions are considered. In this paper, an energy-efficient proportional-fair scheduling is proposed for downlink multi-user MIMO systems. To specific, the scheduling algorithm is proposed to balance cell-edge energy-efficiency and the cell-average energy-efficiency. The energy-efficient proportional-fair metric is defined and the optimal power allocation maximizing the performance measure is identified. System level evaluation suggests that multi-user MIMO could improve the energy-efficiency of a wireless communication system significantly.\",\n \"Title: Doa Estimation And Capacity Analysis For 2d Active Massive Mimo Systems\\nYear: 2013\\n\\nAbstract: Mobile data traffic is expected to have an exponential growth in the future. In order to meet the challenge as well as the form factor limitation on the base station, twodimensional (2D) \\\" massive MIMO\\\" has been proposed as one of the enabling technologies for future wireless systems. In 2D \\\" massive MIMO\\\" systems, a base station will rely on the uplink sounding signals to figure out the downlink spatial channel information to perform MIMO precoding. Accordingly, directionof- arrival (DoA) estimation of the underlying three-dimensional (3D) channel at the base station becomes essential for 2D \\\" massive MIMO\\\" systems to realize the predicted capacity gains.In this paper, we will analyze the performance of DoA estimation based on ESPRIT methods and study its impact on the capacity of 2D \\\" massive MIMO\\\" systems. To be specific, for ESPRIT-type algorithms, we will derive the closed-form expressions for the mean square errors of the elevation and azimuth angle estimations. These results will be used to obtain design intuitions for 2D antenna arrays at the base station as well as the capacity of the underlying 2D \\\" massive MIMO\\\" systems.\",\n \"Title: Energy Efficiency of Hybrid Cellular With Heterogeneous QoS Provisions\\nYear: 2014\\n\\nAbstract: In this letter, we consider a hybrid broadcast and unicast cellular network (hybrid cellular for short) with heterogeneous quality of service (QoS) constraints in the low-power regime. In particular, we consider the unicast user with delay constraint and the broadcast user with outage constraint. The transmission energy efficiency of the dirty paper coding (DPC) and time division multiple access (TDMA) schemes are analyzed and compared from information theoretic point of view. Specifically, the minimum energy per bit and the wideband slope region are derived in closed forms. While both DPC and TDMA schemes require the same minimum energy per bit, DPC outperforms TDMA with regard to the wideband slope region. We also obtain the critical points for both schemes beyond which the wideband slope decreases for both unicast and broadcast users. Finally, we show how the heterogeneous QoS constraints affect the energy efficiency in hybrid cellular.\",\n \"Title: Resource Allocation for OFDM Cognitive Radio With Enhanced Primary Transmission Protection\\nYear: 2014\\n\\nAbstract: Reducing interference to primary users and achieving good throughput are key objectives for secondary users in a cognitive radio (CR) network. In this letter, a rate loss constraint is considered in the sensing based spectrum sharing system of an OFDM CR network. Optimal resource allocation strategies including both sensing time and power allocation schemes are investigated to maximize the ergodic throughput of a secondary user under the rate loss constraints for primary users. A low complexity algorithm is introduced to characterize the optimal power allocation based on the sensing outcome at the SU. The effectiveness of the proposed resource allocation algorithms are demonstrated through simulation.\",\n \"Title: Energy-Efficient Power Allocation for Delay-Sensitive Multimedia Traffic Over Wireless Systems\\nYear: 2014\\n\\nAbstract: With the extremely high penetration rate of wireless broadband devices, the telecommunication industry predicts that the mobile data traffic will double almost every year for the next five years with more than two-thirds of the future traffic being mobile video. This trend clearly indicates that future mobile broadband networks will face the dual challenge of supporting large data volumes while providing reliable service for delay-sensitive mobile multimedia streams. This explosive demand for mobile multimedia communications has significantly increased not only spectrum requirements but also energy consumption. Energy-efficient communication is becoming a prime concern for mobile multimedia communications partially due to the fact that improvements in battery technology occur on a much slower scale than gains in processing power and energy consumption of electronic devices. Furthermore, the ever-increasing demand for wireless services and ubiquitous network access comes at the expense of a growing carbon footprint for the mobile wireless communication industry. This paper addresses resource allocation to maximize the energy efficiency of a wireless link under statistical quality-of-service (QoS) constraints for mobile multimedia traffic. In the energy-efficiency analysis, both circuit and transmit power values of mobile devices are taken into account. The joint impact of statistical QoS constraints, underlying circuit power consumption, transmission power, and spectral bandwidth is considered. The unique globally optimal power allocation scheme for delay-sensitive multimedia traffic is characterized. Intuition about optimal strategies is obtained by looking at both the low-signal-to-noise-ratio (SNR) regime and the high-SNR regime.\",\n \"Title: Cooperative Communications For Lte-Advanced-Relay And Comp\\nYear: 2014\\n\\nAbstract: The Long Term Evolution-Advanced (LTE-A) system is currently under development to allow for significantly higher spectral efficiency and data throughput than the LTE systems. In a wireless system based on orthogonal frequency division multiplexing with frequency reuse factor one, the achievable cell spectral efficiency is often limited by the inter-cell interference or coverage shortage of base stations. In LTE-A, coordinated multi-point transmission/reception (a.k.a. multi-cellMIMO or base station cooperation) and relaying technologies are being introduced to clear these major performance hurdles. In this paper, cooperative communication technologies being discussed in LTE-A systems are presented, together with considerations on system design. Copyright (C) 2012 John Wiley & Sons, Ltd.\",\n \"Title: Cooperative transmission for cognitive radio networks using mutual-information accumulation\\nYear: 2014\\n\\nAbstract: In cognitive radio networks, secondary users (SUs) have to control their transmission power so that the interference to primary users' (PUs) are tolerable. Under this situation, SUs will transmit at a relatively low power level experiencing high bit error rate with limited coverage range. To address this problem, cooperative transmission using mutual information accumulation is introduced to cognitive radio networks. To be specific, resource allocation problem in such a network is investigated and is factored into two sub-problems, each of which can be solved efficiently. The simulation results show that mutual information accumulation can significantly decrease the delay of a cognitive radio network especially in the scenario where the PU has a tight interference power constraint.\",\n \"Title: Optimal resource allocation for sensing based spectrum sharing cognitive radio networks\\nYear: 2014\\n\\nAbstract: To improve the spectral efficiency of a cognitive radio system, sensing based spectrum sharing (SBSS) technique combines the advantages of spectrum overlay and spectrum underlay. In this paper, we study the performance of SBSS under primary users' (PUs') rate loss constraint. To be specific, efficient algorithms are introduced to find the optimal sensing time and power allocation in both single-carrier and multi-carrier systems. Performance evaluation is conducted to compare the system throughput between SBSS and spectrum overlay techniques. Simulation results suggest that SBSS outperforms spectrum overlay when the transmitter of the secondary user (SUT) is far away from the receiver of the primary user (PUR) in the single-carrier case. In the multi-carrier case, SBSS can achieve 15.2% increase of spectral efficiency over spectrum overlay when all the channel gains are independent and identically distributed.\",\n \"Title: Joint angle and delay estimation for 2D active broadband MIMO-OFDM systems.\\nYear: 2013\\n\\nAbstract: Mobile data traffic is expected to have an exponential growth in the future. In order to meet the challenge as well as the form factor limitation at the base station, 2D \\\"Massive MIMO\\\", combined with OFDM, has been proposed as one of the enabling technologies to significantly increase the spectral efficiency of a broadband wireless system. In 2D broadband MIMO-OFDM systems, a base station will rely on the spatial information extracted from uplink sounding reference signals to perform downlink MIMO beam-forming. Accordingly, multi-dimensional parameter estimation of a ray-based multipath wireless channel becomes crucial for such systems to realize the predicted capacity gains. In this paper, we study joint angle and delay estimation for 2D broadband MIMO-OFDM systems and analytically assess its estimation performance. To be specific, a tensor-based standard ESPRIT algorithm is naturally applied to estimate the corresponding 3D channel parameters. Further, we give out the closed-form mean square error expressions for DoA estimation. It is found that the dimensionality of the antenna array at the base station, as well as the implementation of OFDM, play an important role in determining the estimation performance. Simulation is conducted to evaluate the performance of the tensor-based ESPRIT algorithm, and the empirical results match very well with that from the derived analytical expressions. These insights will be useful for designing practical 2D broadband MIMO-OFDM systems in future mobile wireless communications.\",\n \"Title: Channel coding over finite transport blocks in modern wireless systems.\\nYear: 2013\\n\\nAbstract: In modern wireless systems such as 3GPP LTE/LTE-Advanced, packets are partitioned into multiple transport blocks where each transport block is a group of resource elements with a common modulation and coding scheme. Accordingly, a transport block is the data unit in the physical layer of modern wireless systems. In this paper, we investigate the throughput performance of modern wireless systems under channel coding over finite transport blocks. When we apply coding over multiple transport blocks, the underlying wireless channel can be effectively modeled as a finite-state discrete-time Markov chain. We link the characteristics of the underlying physical channel to the parameters of the Markov chain, and derive the corresponding \\\"channel dispersion.\\\" The \\\"channel dispersion\\\" is then used to assess the throughput performance of various communication strategies. The results show that for a fixed packet size the system throughput increases with transport block size.\",\n \"Title: DoA estimation and achievable rate analysis for 3D millimeter wave massive MIMO systems\\nYear: 2014\\n\\nAbstract: Mobile data traffic is predicted to grow exponentially in the future. To address the challenge and consider the form factor limitation at the base station, 3D millimeter wave massive MIMO has been introduced as an enabling technology for 5G systems. In 3D millimeter wave massive MIMO systems, due to the large number of antennas and limited number of clusters, a base station will mainly rely on the uplink sounding signals instead of the feedback to figure out the channel knowledge to perform 3D MIMO operation. Accordingly, multi-dimensional channel estimation becomes critical for such systems to realize the predicted rate gains. In this paper, the performance of direction of arrival (DoA) estimation at the base station using ESPRIT method is characterized. The DoA estimation is further related to the underlying 3D MIMO achievable rate and the optimal transmission strategy is characterized. Finally, the impact of channel estimation error on the underlying achievable rate is analyzed. Our results suggest that DoA estimation is crucial for the transmit beam-forming of 3D millimeter wave massive MIMO systems. Furthermore, the optimal transmission strategy depends heavily on the performance of the underlying DoA estimation.\",\n \"Title: Coding Across Finite Transport Blocks in Modern Wireless Communication Systems\\nYear: 2014\\n\\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In light of this challenge, this paper investigates the throughput performance of wireless communication systems under channel coding over finite transport blocks (TBs) with the channel state sequence available only at the receiver. When we apply coding across multiple TBs, the underlying wireless channel can be effectively modeled as a finite-state Markov chain. By linking the characteristics of the underlying physical channel to the parameters of the Markov chain, we characterize the channel dispersion of the corresponding system. The channel dispersion is then used to assess the coding performance of various communication strategies. We also propose a communication scheme where the receiver determines the decoding time based on the available channel state sequence. Numerical results show that the proposed scheme significantly reduces the coding delay to achieve rates near the channel capacity.\",\n \"Title: Early decoding for transmission over finite transport blocks\\nYear: 2014\\n\\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In the light of this challenge, this paper investigates the throughput performance of wireless systems under channel coding over finite transport blocks (TBs) with the channel state sequence available only at the receiver. We analyze the performance of a communication scheme with feedback, namely early decoding, where for each codeblock the receiver makes a single decoding attempt at a time determined based on the available channel state information. A finite-state Markov channel (FSMC) is introduced to model the TB-based wireless system where the parameters of the model are linked to the characteristics of the underlying physical channel. The FSMC model is then used to assess the maximum achievable throughput of the early decoding strategy. Numerical results suggest that despite its low computational complexity the proposed scheme significantly reduces the coding latency to achieve rates near the channel capacity.\",\n \"Title: On the finite blocklength performance of HARQ in modern wireless systems\\nYear: 2014\\n\\nAbstract: Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In the light of this challenge, this paper investigates the throughput performance of hybrid automatic repeat request (HARQ) systems under finite blocklength constraint. We present a framework to compute the maximum achievable rate with HARQ over the Rayleigh fading channel for a given probability of error. In the proposed framework, the operation of HARQ over the Rayleigh fading channel is modeled as a finite-state Markov chain. The state transition probabilities of the proposed Markov model are estimated from the fading characteristics of the wireless channel as well as the dispersion associated with different channel state sequence realizations. With this framework we are able to link the HARQ throughput performance to the characteristics of the underlying physical channel as well as the system design parameters such as modulation and transmit power. Furthermore, we discuss the relationship between the system throughput, and the number of HARQ rounds. The results show that the required number of HARQ rounds to take full advantage of HARQ depends on the choice of modulation, and varies as a function of the signal-to-noise ratio (SNR).\",\n \"Title: Cooperative Transmission for Wireless Networks Using Mutual-Information Accumulation\\nYear: 2011\\n\\nAbstract: Cooperation between the nodes of wireless multihop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual information accumulation. In this paper, we investigate resource allocation for unicast and multicast transmission in such networks. Given a network, a source, and a destination, our objective is to minimize end-to-end transmission delay under energy and bandwidth constraints. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any transmission order we show that solving for the optimum resource allocation can be formulated as a linear programming problem. We then show that the transmission order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear programs leads to a locally optimal solution in a very efficient manner. In comparison to the proposed cooperative routing solution, it is observed that conventional shortest path multihop routing typically incurs additional delays and energy expenditures on the order of 70%. Drawing inspiration from this first, centralized, algorithm, we also present two distributed algorithms. These algorithms require only local channel state information. Simulations indicate that they yield solutions about two to five percent less efficient than the centralized algorithm.\",\n \"Title: Subspace Identification for DOA Estimation in Massive / Full-dimension MIMO System: Bad Data Mitigation and Automatic Source Enumeration\\nYear: 2015\\n\\nAbstract: this paper, the direction-of-arrival (DOA) estimation problem for massive multiple-input multipleoutput (MIMO) systems with a two dimensional (2D) array (also known as full-dimension MIMO) is investigated, assuming no knowledge of path number, noise power, path gain correlations and bad data statistics. Based on the variational Bayesian framework, a novel iterative algorithm for subspace identification operating on tensor represented data is proposed with integrated features of effective bad data mitigation and automatic source enumeration. The subspace recovered from the proposed algorithm not only enables existing 2D DOA estimators to be readily applied, if the number of signal paths is less than the number of horizontal antennas and vertical antennas, the subspaces in elevation and azimuth domains can be separately estimated, from which one dimensional (1D) DOA estimators can be utilized, thus further lowering the complexity. Simulation results are presented to illustrate the excellent performance of the proposed subspace recovery method and subsequent DOA estimation in terms of accuracy and robustness.\",\n \"Title: Cooperative Routing For Underlay Cognitive Radio Networks Using Mutual-Information Accumulation\\nYear: 2015\\n\\nAbstract: In underlay cognitive radio networks (CRNs),secondary users (SUs)have to dynamically control their transmit powers so that the interference to primary users (PUs) is tolerable. Under this constraint, SUs' data link usually suffers from either high error rate with limited transmission range or long end-to-end delay caused by multi-hop transmissions. To improve the performance of SUs, cooperative routing using mutual-information accumulation is introduced in CRNs for the first time in this paper. To be specific, the routing and resource allocation problem in underlay CRNs is investigated and is factored into two sub-problems, each of which can be solved efficiently. Furthermore, a distributed algorithm is introduced and simulation results show that both the centralized and distributed algorithms can reduce upto 77% of the end-to-end delay compared to the traditional multi-hop delay-optimal routing in CRNs. Finally, theoretical analysis on the end-to-end delay for a one-dimensional (1-D) network in the low signal-to-interference ratio (SIR) region is conducted. Both the analytical and simulation results show that mutual-information accumulation can significantly decrease the delay of underlay CRNs, especially in the scenario where PUs have a tight interference power constraint.\",\n \"Title: Resource Allocation for Delay-Sensitive Traffic over LTE-Advanced Relay Networks\\nYear: 2015\\n\\nAbstract: Future wireless networks will face the dual challenge of supporting large traffic volumes while providing reliable service for delay-sensitive traffic. To meet the challenge, relay network has been introduced as a new network architecture for the fourth generation (4G) LTE-Advanced (LTE-A) networks. In this paper, we investigate resource allocation including subcarrier and power allocation for LTE-A relay networks under statistical quality of service (QoS) constraints. By dual decomposition, we derive the optimal subcarrier and power allocation strategies to maximize the effective capacity (EC) of the underlying LTEA relay systems. Characteristics of optimal resource allocation strategies are identified, and a low-complexity suboptimal scheme is developed through optimizing the subcarrier and power allocation individually. Our result suggests that the optimal subcarrier and power allocation strategies depend heavily on the underlying QoS constraint. For example, in the low signal-to-interference-plus-noise (SINR) regime, when there are less stringent QoS constraints, base stations and relay stations tend to allocate all the power to the best available subcarrier. However, as QoS requirements become more stringent, both base stations and relay stations will spread their power over available subcarriers. On the other hand, in the high SINR regime, regardless of the QoS constraints, base stations and relay stations tend to equally allocate power among available subcarriers.\",\n \"Title: Energy-Efficient Resource Allocation for MIMO-OFDM Systems Serving Random Sources With Statistical QoS Requirement\\nYear: 2015\\n\\nAbstract: This paper optimizes resource allocation that maximizes the energy efficiency (EE) of wireless systems with statistical quality of service (QoS) requirement, where a delay bound and its violation probability need to be guaranteed. To avoid wasting energy when serving random sources over wireless channels, we convert the QoS exponent, a key parameter to characterize statistical QoS guarantee under the framework of effective bandwidth and effective capacity, into multi-state QoS exponents dependent on the queue length. To illustrate how to optimize resource allocation, we consider multi-input-multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A general method to optimize the queue length based bandwidth and power allocation (QRA) policy is proposed, which maximizes the EE under the statistical QoS constraint. A closed-form optimal QRA policy is derived for massive MIMO-OFDM system with infinite antennas serving the first order autoregressive source. The EE limit obtained from infinite delay bound and the achieved EEs of different policies under finite delay bounds are analyzed. Simulation and numerical results show that the EE achieved by the QRA policy approaches the EE limit when the delay bound is large, and is much higher than those achieved by existing policies considering statistical QoS provision when the delay bound is stringent.\",\n \"Title: Optimal resource allocation for sensing-based spectrum sharing D2D networks.\\nYear: 2015\\n\\nAbstract: To improve the spectral efficiency of a cellular network, sensing based spectrum sharing device-to-device (sensing-based D2D) technique is introduced in this paper. To be specific, efficient algorithms are introduced to find the optimal sensing time and power allocation for single-subband sensing-based D2D systems under cellular link’s rate loss constraint. For multi-subband systems, D2D users may have limited sensing capability where only a part of the subbands can be sensed. Accordingly, a partially observable Markov decision process (POMDP) model is introduced and an efficient algorithm is introduced to address the resource allocation problem.\",\n \"Title: Smart backhauling and fronthauling for 5G networks: from precoding to network architecture [Guest editorial]\\nYear: 2015\\n\\nAbstract: The recent widespread use of mobile Internet together with the advent of many smart applications has led to the explosive growth of mobile data traffic in the last few years. This remarkable growing momentum of mobile traffic will most likely continue due to the emerging needs of connecting people, machines, and applications through mobile infrastructure. As a result, the current and projected dra...\",\n \"Title: Energy-efficient resource allocation of wireless systems with statistical QoS requirement\\nYear: 2014\\n\\nAbstract: This paper strives to improve the energy efficiency (EE) of wireless systems by resource allocation for delay sensitive traffic with the statistical quality of service (QoS) requirement, where a delay bound and a small violation probability is ensured. To avoid wasting energy when serving random traffic, we turn the QoS exponent, a key parameter to characterize statistical QoS guarantee under the framework of effective bandwidth and effective capacity, into a QoS function dependent on the queue length. A method to design queue length based resource allocation strategy is proposed, which maximizes the EE under the constraint on the QoS function. By taking an OFDM system serving Poisson source as an example, a closed form subcarrier allocation strategy with constant transmit power on each subcarrier is derived. Simulation and numerical results show that the EE achieved by the proposed strategy is much higher than the relevant strategies in the literature considering statistical QoS provision, and is very close to the EE upper bound achieved when the delay bound is infinite.\",\n \"Title: Interference Alignment And Leakage-Based Iterative Coordinated Beam-Forming For Multi-User Mimo In Lte-Advanced\\nYear: 2015\\n\\nAbstract: To suppress co-channel interference and achieve good system performance in a Multi-User Multiple Input Multiple Output (MU-MIMO) downlink network, we introduce a novel Interference Alignment (IA) receive matrix design methodology along with a low complexity iterative coordinated beamforming scheme. The introduced scheme takes into account the codebook-based feedback for LTE/LTE-Advanced systems. In our design, IA is utilized to mitigate the inter-cell interference while leakage-based iterative coordinated beamforming is used to combat the intra-cell interference. Optimal transmit beamforming vectors are characterized and a closed-form expression for these beamforming vectors in the presence of quantization error due to the codebook-based feedback is also presented. Simulation is conducted to illustrate the performance of introduced coordinated beamforming strategy. It suggests that for 4 by 2 MIMO systems, rank 2 codebook-based feedback yields much better performance than rank 1 feedback. Furthermore, for a fixed payload size of the codebook, unlike zero-forcing beamforming where the sum throughput is bounded as the signal-to-noise ratio (SNR) increases, in our scheme the performance gap between the rank 2 feedback and perfect feedback remains almost constant as SNR increases.\",\n \"Title: On The Queueing Performance Of Harq Systems With Coding Over Finite Transport Blocks\\nYear: 2015\\n\\nAbstract: With the growing popularity of mobile applications such as voice over IP (VoIP) and real-time conversational video, and due to the scarcity of the available radio spectrum, increasing the spectral efficiency of wireless systems under quality of service (QoS) constraints becomes increasingly important. Accordingly, in this paper we investigate the maximum achievable rate of incremental redundancy type hybrid automatic repeat request (IR-HARQ) over the Rayleigh fading channel under probability of error, and queueing delay violation probability constraints, in the finite code blocklength regime.We model the Rayleigh fading channel by a finite-state Markov channel (FSMC) where the channel in each state is modeled as additive white Gaussian noise (AWGN). We derive the dispersion of parallel AWGN channels with finite input alphabets (e.g. pulse amplitude modulation (PAM)), which is used to track the operation of IR-HARQ over the wireless channel for a given modulation scheme, and coding rate. We then use a two-dimensional Markov process tracking the time evolution of a queueing system, where data packets arriving at the queue are transmitted over the wireless channel with IR-HARQ. This Markov process is used to derive an upper bound on the queueing delay violation probability and to jointly approximate the average rate and the average probability of error of HARQ as a function of the modulation scheme and the coding rate. Finally, we present numerical results.\",\n \"Title: Modeling and Analysis of Energy Consumption for RF Transceivers in Wireless Cellular Systems.\\nYear: 2015\\n\\nAbstract: In this paper, a comprehensive model has been provided to study the energy consumption of wireless cellular devices, by analyzing the relationship between the modulation order and energy consumption of the power amplifier (PA) and other circuits in radio frequency transceivers. Two types of energy consumption for PAs are studied in detail: transmitted energy, which is provided to the antenna to transmit data, and energy dissipated as a heat. First, the transmitted energy is studied along with different modulation orders for different distances between the transmitter and receiver. Next, the dissipated energy with all corresponding parameters such as peak to average ratio (PAR) and the drain efficiency of the PA is discussed. Other circuits are examined to show that the energy of these circuits-unlike other models in the literature-change with modulation order. The results reinforce the idea that increasing the modulation order leads to higher energy consumption in the RF transceiver for large distance. The results also show that the energy dissipated due to PAR and drain efficiency is larger than the transmitted energy.\",\n \"Title: DoA Estimation and RMSE Characterization for 3D Massive-MIMO/FD-MIMO OFDM System.\\nYear: 2015\\n\\nAbstract: With the promise of meeting future capacity demands for mobile broadband communications, 3D massive-MIMO/Full Dimension MIMO (FD-MIMO) systems have gained much interest among the researchers in recent years. Apart from the huge spectral efficiency gain offered by the system, the reason for this great interest can also be attributed to significant reduction of latency, simplified multiple access layer, and robustness to interference. However, in order to completely extract the benefits of massive-MIMO systems, accurate channel state information is very critical. In this paper, a channel estimation method based on direction of arrival (DoA) estimation is presented for massive-MIMO OFDM systems. To be specific, the DoA is estimated using Estimation of Signal Parameter via Rotational Invariance Technique (ESPRIT) method, and the root mean square error (RMSE) of the DoA estimation is analytically characterized for the corresponding MIMO-OFDM system.\",\n \"Title: Robust Tensor-Based DOA Estimation in Massive / Full-Dimension MIMO System.\\nYear: 2015\\n\\nAbstract: In this paper, direction-of-arrival (DOA) estimation problem for massive multiple-input multiple-output (MIMO) systems with a two dimensional (2D) array is investigated, assuming no knowledge of path number, noise power, path gain correlations and bad data statistics. A novel iterative algorithm operating on tensor represented data is proposed, with integrated features of effective bad data mitigation and automatic source enumeration. Simulation results are presented to illustrate the excellent performance of the proposed algorithm in term of accuracy and robustness.\",\n \"Title: Resource Allocation For Sensing-Based Device-To-Device (D2d) Networks\\nYear: 2015\\n\\nAbstract: Resource allocation for sensing-based D2D networks is investigated in this paper. To be specific, we introduce the concept of spatial spectrum sensing where D2D users can sense spatial spectrum opportunities in a cellular network. By modeling the location of base stations and cellular users as Poisson point processes (PPP), the spatial spectrum sensing problem can be formulated using the framework of detection theory. The closed-form expressions are obtained for probabilities of spatial detection, probability of spatial false alarm, and sensing threshold. Accordingly, simulation results are provided to verity our analysis.\",\n \"Title: DoA estimation and achievable rate analysis for 3D massive MIMO in aeronautical communication systems\\nYear: 2015\\n\\nAbstract: With very high carrier frequencies (such as millimeter-wave (mmW) bands), a very large number of antennas can be packed at the base station (BS). For this kind of high dimensional channel, it is desirable to exploit signal directions to estimate the channel directions. In this paper, we analyze the performance of the direction of arrival (DoA) estimation based on unitary ESPRIT algorithm assuming time division duplex (TDD) wideband system. The mean-squared error (MSE) of the 2D DoA estimation of a multipath signal impinging on a planar antenna array is derived. Accordingly, we propose a power allocation strategy that counts for the DoA estimation error. The achievable rate characterization suggests that our power allocation strategy outperforms the traditional water-filling solution.\",\n \"Title: DoA estimation and capacity analysis for 3D massive-MIMO/FD-MIMO OFDM system\\nYear: 2015\\n\\nAbstract: With the promise of meeting future capacity demands for mobile broadband communications, 3D massive-MIMO/Full Dimension MIMO (FD-MIMO) systems have gained much interest among the researchers in recent years. Apart from the huge spectral efficiency gain offered by the system, the reason for this great interest can also be attributed to significant reduction of latency, simplified multiple access layer, and robustness to interference. However, in order to completely extract the benefits of massive-MIMO systems, accurate channel state information is very critical. In this paper, a channel estimation method based on direction of arrival (DoA) estimation is presented for massive-MIMO OFDM systems. To be specific, the DoA is estimated using Estimation of Signal Parameter via Rotational Invariance Technique (ESPRIT) method, and the capacity of the system is analytically characterized. It has been shown that optimum precoding matrix for the massive MIMO OFDM system can be constructed from the DoA estimation at the base station.\",\n \"Title: Dynamic Allocation of RACH Resource for Clustered M2M Communications in LTE Networks.\\nYear: 2015\\n\\nAbstract: In this paper, we propose a dynamic allocation scheme of random access channel (RACH) resource for clustered machine-to-machine (M2M) communications, in which delay-sensitive services coexist with delay-tolerant ones. Our scheme aims at alleviating the overload and congestion of machine-type (MTC) communication as well as satisfying both delay-sensitive and delay-tolerant services. Specifically, the operation of our protocol includes three aspects. First, in order to make full use of the preamble resources controlled by the Enhanced Node B (eNB), our proposed scheme adopts a two-cluster networking, where MTC devices are divided into two clusters based on their requirements on delay. Second, we develop the dynamic allocation scheme to partition the available preambles for each cluster under the condition of guaranteeing the preferable number of successful devices. Third, the devices belonging to different clusters adopt the access class barring (ACB) mechanism respectively. Simulation results show that our proposed scheme realizes the remarkable increase in improving the access success probability and achieve performance improvement in reducing access delay.\",\n \"Title: Device-To-Device Relay Assisted Cellular Networks With Token-Based Incentives\\nYear: 2015\\n\\nAbstract: We consider a device-to-device (D2D) relayassisted cellular network where mobile transceivers that are owned by self-interested users are incentivized to relay each other's data using tokens, which they exchange electronically to \\\"buy\\\" and \\\"sell\\\" downlink relay services. We formulate the decision problem faced by each UE, namely, the problem of deciding whether or not to relay, as a Markov decision process (MDP). We propose a supervised learning algorithm that devices can deploy to learn their optimal relay policies online given their experienced network environment. Our simulation results show that, within the proposed token system, self-interested devices can achieve almost 15% higher throughput on average, and almost 40% higher throughput at the 90th percentile, than with only direct base-station-to-device communications. Additionally, we show that the token system performs best when the network contains neither too few nor too many tokens.\",\n \"Title: Proportional-Fair Resource Allocation for Coordinated Multi-Point Transmission in LTE-Advanced.\\nYear: 2016\\n\\nAbstract: Coordinated multi-point (CoMP) transmission and reception are introduced as a promising technology in the 3GPP LTE-advanced standard, to manage interference, improve the overall system performance, and enhance system reliability. In this paper, a resource allocation problem is studied for downlink CoMP coordinated beamforming systems, where each base station (BS) serves its own mobile stations. Multiple-input-multiple-output (MIMO) transmit precoding and resource allocation are linked to the underlying proportional-fair scheduling to ensure a good trade-off between cell-average and cell-edge user spectral-efficiency. Due to the coupled interference among mobile stations, the resulting proportional-fair resource allocation optimization problem becomes nonconvex. To solve for optimal operating point for MIMO CoMP network, a parallel successive convex approximation-based algorithm is introduced. The introduced scheme enables all BSs to update their optimization variables in parallel by solving a sequence of strongly convex subproblems. Closed-form expressions of the locally optimal solution in both the high and low signal-to-noise regimes are characterized. The performance of the introduced scheme is also investigated through simulations. Numerical results show the efficiency of the introduced algorithm.\",\n \"Title: Spatial Spectrum Sensing-Based Device-to-Device Cellular Networks.\\nYear: 2016\\n\\nAbstract: Ultra-densification is one of the main features of 5G networks. In an ultra-dense network, how to conduct interference management and spectrum allocation is a challenging issue. Spectrum sensing in cognitive radio networks is a distributed and efficient way to resolve this issue in ultra-dense networks. However, most of the studies on spectrum sensing only focus on sensing temporal spectrum opportunities where one or multiple primary users are active, which does not make full use of spectrum opportunities in the spatial location domain. To overcome the shortcomings of conventional temporal spectrum sensing, we study the problem of spatial spectrum sensing, which senses spatial spectrum opportunities in wireless networks. In this paper, the performance of spatial spectrum sensing and its application in sensing-based device-to-device (D2D) cellular networks are analyzed using stochastic geometry. Specifically, by modeling the locations of active transmitters as a Poisson point process, the spatial spectrum sensing problem is formulated using the framework of a detection theory. Closed-form expressions are obtained for the sensing threshold, probabilities of spatial detection, and false alarm. Furthermore, analytical throughput for D2D users and cellular users under both channel inversion and constant power allocation cases are derived. The optimal sensing radius that maximizes the defined network metric is obtained numerically. Finally, the simulation and numerical results are presented to verify our theoretical analysis.\",\n \"Title: DoA Estimation and Capacity Analysis for 3-D Millimeter Wave Massive-MIMO/FD-MIMO OFDM Systems.\\nYear: 2016\\n\\nAbstract: With the promise of meeting future capacity demands, 3-D massive-MIMO/full dimension multiple-input-multiple-output (FD-MIMO) systems have gained much interest in recent years. Apart from the huge spectral efficiency gain, 3-D massive-MIMO/FD-MIMO systems can also lead to significant reduction of latency, simplified multiple access layer, and robustness to interference. However, in order to comple...\",\n \"Title: Dynamic RACH Partition for Massive Access of Differentiated M2M Services.\\nYear: 2016\\n\\nAbstract: In machine-to-machine (M2M) networks, a key challenge is to overcome the overload problem caused by random access requests from massive machine-type communication (MTC) devices. When differentiated services coexist, such as delay-sensitive and delay-tolerant services, the problem becomes more complicated and challenging. This is because delay-sensitive services often use more aggressive policies, and thus, delay-tolerant services get much fewer chances to access the network. To conquer the problem, we propose an efficient mechanism for massive access control over differentiated M2M services, including delay-sensitive and delay-tolerant services. Specifically, based on the traffic loads of the two types of services, the proposed scheme dynamically partitions and allocates the random access channel (RACH) resource to each type of services. The RACH partition strategy is thoroughly optimized to increase the access performances of M2M networks. Analyses and simulation demonstrate the effectiveness of our design. The proposed scheme can outperform the baseline access class barring (ACB) scheme, which ignores service types in access control, in terms of access success probability and the average access delay.\",\n \"Title: Novel Spike based Reservoir Node Design with High Performance Spike Delay Loop.\\nYear: 2016\\n\\nAbstract: With the emerging cutting-edge semiconductor nanotechnologies, reservoir computing has shifted the focus from software implementation towards hardware and optical implementations over the last few decades. Nowadays, in the field of reservoir computing, pure analog implementation with the employment of CMOS nanotechnology has attracted a worldwide attention. In this paper, we introduce a spike-based analog reservoir node with compact delay performing at extremely high accuracy. The detailed work on this novel spike processor working in near chaotic condition is presented and analyzed. Furthermore, we announce a novel class of spike-based delay loop which enables the pure spike implementation of reservoir computing. The simulation results demonstrated that our delay loop possesses exceptionally high accuracy of 99.24% and gain-hold property without adopting any kind of amplifiers. Our proposed reservoir node has shown the potential of transforming spike signals to a high-dimensional state space.\",\n \"Title: Performance Analysis on Nano-Networks: A Stochastic Geometry Approach.\\nYear: 2016\\n\\nAbstract: Pulse based communication scheme, e.g., On-OFF Keying modulation Spread in Time (TS-OOK), is currently the only solution for nano-networks. In this paper, we present an initial analysis on the performance of pulse based communication scheme in nano-networks using stochastic geometry. To be specific, by modeling the transmission of pulse as random events, we theoretically characterize the cumulative distribution function of signal-to-interference-plus-noise ratio and link throughput in nano-networks. Furthermore, both simulation and numerical results are presented to verify our analysis. Our results show that low-weight codes for TS-OOK can significantly increase the average throughput in dense nano-networks where the interference cannot be neglected.\",\n \"Title: Interference Alignment for Downlink Multi-Cell LTE-Advanced Systems With Limited Feedback.\\nYear: 2016\\n\\nAbstract: To suppress the co-channel interference in a multi-cell multi-user multiple-input-multiple-output downlink cellular network, a novel interference alignment transceiver beam-forming design along with a low complexity iterative coordinated beam-forming scheme is introduced. While the latter combats the intra-cell interference, the former is utilized to mitigate the inter-cell interference. The proposed schemes consider the codebook-based feedback, which is adopted in the LTE/LTE-advanced systems. Optimal downlink user-specific and cell-specific beam-forming matrices are characterized to maximize the lower bound of expected signal-to-leakage-plus-noise ratio and to minimize the residual inter-cell interference, respectively. Moreover, closed-form expressions for these beam-forming matrices under limited channel state information feedback and in the presence of the quantization error are identified. Simulations are conducted to investigate the performance of the proposed strategy. The results indicate that our scheme can significantly improve the average spectral-efficiency of the underlying network when compared with existing ones where the quantization error is neglected. Furthermore, for a fixed payload size of the codebook, unlike zero-forcing beam-forming in which the sum throughput is bounded as the signal-to-noise ratio (SNR) increases, in our scheme, the performance gap between rank 2 feedback and perfect feedback remains approximately constant as SNR increases.\",\n \"Title: Urban Link Travel Time Prediction Based on a Gradient Boosting Method Considering Spatiotemporal Correlations.\\nYear: 2016\\n\\nAbstract: The prediction of travel times is challenging because of the sparseness of real-time traffic data and the intrinsic uncertainty of travel on congested urban road networks. We propose a new gradient-boosted regression tree method to accurately predict travel times. This model accounts for spatiotemporal correlations extracted from historical and real-time traffic data for adjacent and target links. This method can deliver high prediction accuracy by combining simple regression trees with poor performance. It corrects the error found in existing models for improved prediction accuracy. Our spatiotemporal gradient-boosted regression tree model was verified in experiments. The training data were obtained from big data reflecting historic traffic conditions collected by probe vehicles in Wuhan from January to May 2014. Real-time data were extracted from 11 weeks of GPS records collected in Wuhan from 5 May 2014 to 20 July 2014. Based on these data, we predicted link travel time for the period from 21 July 2014 to 25 July 2014. Experiments showed that our proposed spatiotemporal gradient-boosted regression tree model obtained better results than gradient boosting, random forest, or autoregressive integrated moving average approaches. Furthermore, these results indicate the advantages of our model for urban link travel time prediction.\",\n \"Title: Energy Efficient Spiking Temporal Encoder Design for Neuromorphic Computing Systems.\\nYear: 2016\\n\\nAbstract: Neuromorphic computing hardware has undergone a rapid development and progress in the past few years. One of the key components in neuromorphic computing systems is the neural encoder which transforms sensory information into spike trains. In this paper, both rate encoding and temporal encoding schemes are discussed. Two novel temporal encoding schemes, parallel and iteration, are presented. The p...\",\n \"Title: FPGA based spike-time dependent encoder and reservoir design in neuromorphic computing processors.\\nYear: 2016\\n\\nAbstract: In this paper, we propose a Field Programmable Gate Array (FPGA) platform for spike time dependent encoder and dynamic reservoir in neuromorphic computing processors. Neuromorphic computing processors represent a type of non-traditional architecture encompassing evolutionary systems and hold great promise for many important engineering and scientific applications. The reservoir computing approach with dynamic reservoir is a paradigm in machine learning whose processing capabilities rely on the dynamical behavior of Recurrent Neural Networks (RNNs). It has made swift progress and development in both the theoretical realm and its subsequent implementations. However, most of the implementations are based on software, due to the difficulties in performing real-time training of the output weights on hardware platforms. The reservoir computing approach implemented in this paper utilizes the Echo State Network (ESN) architecture which includes a reservoir and its consequent training process. It can be trained and implemented in FPGA without any software cooperation. As FPGA is a digital logic platform and the information entered into a RNN is analog, we also propose an encoding circuit and an Analog to Digital Converter (ADC) to bridge this divide. The proposed method given for the realization of the neuromorphic computing chips, therefore, provides a viable option.\",\n \"Title: Privacy Protection Scheme for eHealth Systems: A Stochastic Geometry Approach.\\nYear: 2016\\n\\nAbstract: The technological advancements in the health care system have made possible the massive integration of biomedical sensors for monitoring patients' health and disease progression. In this paper, we consider a three tier medical body area network (MBAN): intra-MBAN, inter-MBAN, and beyond-MBAN. The intra-MBAN transmits sensors' data to a controller, which in turn transmits them in the inter-MBAN tier to an access device like a PDA or a tablet device, usually connected to a patient's medical database. The access device then serves as a mean of communication between intra-MBAN and beyond-MBAN to access the hospital information systems. This widely deployed design in hospitals places security and privacy violation threats on the spotlight of attention, especially in the inter-MBAN tier. This has motivated us to optimize the average MBAN controller transmit power that minimizes the probability of eavesdroppers overhearing the communication, using tools from stochastic geometry. We analyze this privacy protection scheme for eHealth systems through simulations. Results show that the proposed scheme achieves higher privacy protection, but at the expense of reduced coverage.\",\n \"Title: Coordinated Data Assignment: A Novel Scheme for Big Data over Cached Cloud-RAN.\\nYear: 2016\\n\\nAbstract: A cloud radio access network (Cloud-RAN) is a network architecture that holds onto the promise of meeting the explosive growth of mobile data traffic. Cloud-RAN consists a central processor (CP) connecting to multiple multi-antenna base stations (BSs) via finite-capacity backhaul links. To reduce the backhaul traffic, BS-level caching technique is utilized in which the popular contents are pre-fetched in memories at each BS. This technique plays an important role in future wireless big data processing due to its simplicity, low cost, and natural integration with big data analytical tools. Considered the tradeoff between the backhaul and the transmission power cost, in this paper we define the network cost of the system as a normalized weighted sum. The problem of minimizing the network cost with respect to both the precoding matrix and the cache placement matrix is formulated subject to the quality of service (QoS), peak transmission power, and cache capacity constraints. The l 0-norm in the objective function along with the QoS constraints renders the optimization problem non-convex. Additionally, since the entries of cache placement matrix take binary values, the optimization problem falls into a mixed integer nonlinear programming (MINLP) which is a NP-hard problem. An iterative coordinated data assignment algorithm is introduced which achieves a stationary point of the problem. Simulations are conducted to illustrate the performance of introduced algorithm. It suggests that the introduced scheme can significantly reduce the total network cost of the underlying Cloud-RAN network and demonstrate the importance of considering the designing of cache placement matrix.\",\n \"Title: On the Performance of Relay-Assisted D2D Networks under Spatially Correlated Interference.\\nYear: 2016\\n\\nAbstract: With the explosive growth of mobile traffic demand, device-to-device (D2D) communication offers a promising approach to reduce cellular congestion by offloading users' traffic to D2D network. In this paper, we consider a relay-assisted D2D communication in underlay cellular networks, where D2D users access a proportion of the spectrum occupied by cellular users. This poses two fundamental issues. The first issue is related to protecting the cellular transmissions by reducing the spectrum partition factor, which measures the fraction of spectrum available to D2D users. The second issue is that as we limit the spectrum available to D2D users, less D2D transmissions can be supported, which in turn increases the distances between them. To address these issues, we allow a relay user to assist D2D communications in order to achieve higher D2D spectral efficiency without affecting cellular spectral efficiency. In fact, results show significant improvements in spectral efficiency not only to D2D, but to the whole network, especially in a dense D2D environment.\",\n \"Title: Improving Spectral Efficiency of D2D Cellular Networks through RF Energy Harvesting.\\nYear: 2016\\n\\nAbstract: In this paper, we consider device-to-device (D2D) communication underlaying cellular networks, where D2D users harvest radio frequency (RF) power from uplink cellular transmissions. This paper addresses two important issues for energy harvesting-based D2D cellular networks. The first is how the energy harvested from cellular ambient RF signals affects the D2D spectral efficiency. Using tools from stochastic geometry, we investigate this issue by first characterizing the transmission probability of D2D transmitter as the probability of having enough battery power, and then obtaining analytic expressions of the spectral efficiency for D2D and cellular networks. The second issue is related to the cellular spectral efficiency: the more RF energy D2D users can harvest, the higher their transmission probability becomes, which leads to generating more interference in the cellular network. We carry out simulations to understand this impact of RF energy harvesting on the spectral efficiency of both D2D and cellular networks. Results show promising improvement to the whole network, in terms of the weighted spectral efficiency, when employing RF harvesting technology and when there are enough available channels in the network.\",\n \"Title: Cooperative Retransmission for Massive MTC under Spatiotemporally Correlated Interference.\\nYear: 2016\\n\\nAbstract: In a massive machine type communication (massive MTC) network, wireless connections between machine type devices (MTDs) and eNodeBs are unreliable due to the interference caused by uncoordinated access of other MTDs. Furthermore, it is with a high probability that the retransmission from the outage source MTD will fail again due to the spatiotemporally correlated interference. In this paper, we design and analyze a location-based cooperative strategy to improve the performance of massive MTC networks. In the cooperative strategy, an inactive MTD is selected as a relay if it has successfully decoded the packet and if it is located within a circular area around the eNodeB. Considering the spatial and temporal correlation of interference, the outage probability of the designed cooperative strategy is derived using stochastic geometry. Both the simulation and numerical results demonstrate that spatiotemporal correlation of interference significantly affects the performance analysis of cooperative massive MTC networks and our designed cooperative strategy can significantly reduce the outage probability compared to conventional retransmission.\",\n \"Title: Fundamentals of Spatial RF Energy Harvesting for D2D Cellular Networks.\\nYear: 2016\\n\\nAbstract: Energy efficiency is one of the major challenges of 5G networks. As data rates are expected to increase by 1000x from 4G to 5G, energy efficiency will need to improve by about the same amount. Recently, energy harvesting techniques have attracted lots of attention from the scientific community, due to their ability to increase network lifetime. More specific, energy harvesting from ambient radio frequency (RF) signals is of special importance, especially with the recent RF circuit advancements. In this paper, we consider a device-to-device (D2D) communication in underlay cellular networks, where D2D users reuse the spectrum occupied by cellular users. We introduce the concept of spatial RF energy harvesting, where D2D users harvest RF power from uplink cellular transmissions, if it exceeds a predesigned threshold, in a spatial region. Using tools from stochastic geometry, we obtain a closed form expression for the probability of activating RF power conversion circuit by making full use of spatial locations of ambient RF signals. Subsequently, we study the impact of RF energy harvesting region radius to harvest sufficient power on the signal-to-interference (SIR) ratio of D2D network. Simulation results provide insights for the required advancements to design highly efficient RF harvesting circuits.\",\n \"Title: Enabling cyber-physical communication in 5G cellular networks: challenges, spatial spectrum sensing, and cyber-security\\nYear: 2017\\n\\nAbstract: Cyber-physical systems (CPS) help create new services and applications by revolutionising our world in different fields through their tight interactions and automated decisions. This is especially true with the ongoing increase in the number of physical things (sensors, actuators, smartphones, tablets, and so on) along with the explosive increase in the usage of online networking services and appl...\",\n \"Title: Energy Harvesting-Based D2D-Assisted Machine-Type Communications.\\nYear: 2017\\n\\nAbstract: Supporting massive numbers of machine-type communication (MTC) devices poses several challenges for future 5G networks, including network control, scheduling, and powering these devices. A potential solution is to offload MTC traffic onto device-to-device (D2D) communication links to better manage radio resources and reduce MTC devices' energy consumption. However, this approach requires D2D users...\",\n \"Title: Interspike-Interval-Based Analog Spike-Time-Dependent Encoder for Neuromorphic Processors.\\nYear: 2017\\n\\nAbstract: Von Neumann bottleneck, which refers to the limited throughput between the CPU and memory, has already become a major factor hindering the technical advances of computing systems. In recent years, neuromorphic systems have started to gain the increasing attentions as compact and energy-efficient computing platforms. As one of the most crucial components in the neuromorphic computing systems, neura...\",\n \"Title: On the Spectral and Energy Efficiency of Full-Duplex Small-Cell Wireless Systems With Massive MIMO.\\nYear: 2017\\n\\nAbstract: The achievable rate of full-duplex (FD) small-cell systems with massive multiple-input multiple-output (MIMO), in which a low-power base station (BS) equipped with large antenna arrays sends/receives data to and from multiple half-duplex (HD) users at the same time on the same frequency, is investigated. The BS uses imperfect channel state information (CSI) obtained from received pilots, nonideal ...\",\n \"Title: Channel estimation in full-dimensional massive MIMO system using one training symbol.\\nYear: 2017\\n\\nAbstract: In this paper, an algorithm is proposed to estimate thousands of channel parameters in massive multiple-input multiple-output (MIMO) systems with a three-dimensional antenna array, using only one training symbol while assuming no knowledge of path number, noise power, path gain and direction-of-arrival (DOA) statistics. Furthermore, the received data structure is exploited to give a low-complexity DOA acquisition scheme with closed-form computations. Simulation results show excellent performance of the proposed algorithm in both channel estimation and DOA acquisition.\",\n \"Title: Reservoir Computing Meets Smart Grids: Attack Detection Using Delayed Feedback Networks.\\nYear: 2018\\n\\nAbstract: A new method for attack detection of smart grids with wind power generators using reservoir computing (RC) is introduced in this paper. RC is an energy-efficient computing paradigm within the field of neuromorphic computing and the delayed feedback networks (DFNs) implementation of RC has shown superior performance in many classification tasks. The combination of temporal encoding, DFN, and a mult...\",\n \"Title: Distributed MIMO Precoding for In-Band Full-Duplex Wireless Backhaul in Heterogeneous Networks.\\nYear: 2018\\n\\nAbstract: This paper investigates distributed MIMO precoding design to maximize the weighted sum rate in a heterogeneous network where the multiple input multiple output full-duplex (MIMO-FD) small cells reuse the downlink spectrum of the macro base-station (BS) to exchange backhaul information. The multi-antenna BS transmits signals to the cellular users using the dirty paper coding technique and the MIMO-...\",\n \"Title: Modeling and Analysis of Power Amplifier Dissipation Energy in Wireless Handset Transceivers\\nYear: 2018\\n\\nAbstract: The growing demand for high spectral efficiency in 5G communication systems imposes greater energy consumption requirements in wireless handsets. Using spectrally efficient modulations such as multilevel quadrature amplitude modulation (MQAM) introduces challenging requirements for the power amplifier (PA), which consumes the most energy in a wireless handset, and degrades the PA efficiency because of a higher peak-to-average ratio (PAR). In this paper, the impact of using MQAM on the energy dissipation of the PA is examined by capturing the impact of modulation order, PA type, and roll-off factor, along with all corresponding parameters such as PA drain efficiency, the modulation PAR, and the PAR due to the roll-off factor of the transmission pulse. We then investigate different methods for reducing the impact of PAR on PA efficiency. Our results also show that a roll-off factor of 0.42 for a square-root raised cosine (SRRC) pulse can be considered as the optimum choice for wireless communication systems in terms of energy and spectral efficiency. Further, our results show that the linearity and efficiency of class AB PAs can be maintained for very high modulation orders in 5G systems.\",\n \"Title: Lyapunov Scheduling and Optimization in Network Coded Wireless Multicast Network.\\nYear: 2018\\n\\nAbstract: In this paper, we investigate network coding based scheduling in a single-hop wireless multicast network under queueing stability constraint. Specifically, Lyapunov optimization model is adopted and an optimal network coding scheduling algorithm is derived, which significantly reduces the computational complexity and queue length compared to existing solutions. Moreover, two scheduling policies ba...\",\n \"Title: IEEE Access Special Section Editorial: Recent Advances in Full-Duplex Radios and Networks.\\nYear: 2018\\n\\nAbstract: With the explosive growth of wireless communications, frequency resources have become scarcer, considering the dramatically increasing demands for higher communication rates. However, by examining the existing duplex modes, e.g., time division duplex (TDD) and frequency division duplex (FDD), it is observed that more than half of the resources are wasted due to the “half-duplex” constraints, as well as the uses of guard zones in the time or frequency domain to avoid interference from neighbor time slots or frequency bands. Therefore, efficiently utilizing the expensive frequency resources to provide high spectrum-efficient communications becomes one of the most important challenges in the design of the next generation wireless communication systems.\",\n \"Title: Enabling Sustainable Cyber Physical Security Systems through Neuromorphic Computing.\\nYear: 2018\\n\\nAbstract: As the novel paradigm in the field of machine learning, reservoir computing possesses exceptional performance, e.g., energy efficiency, in tasks in which the traditional von Neumann computing systems cannot incorporate. This makes reservoir computing an ideal candidate to enable the sustainable development of cyber-physical systems (CPS). In the realm of CPS, the tight interaction among physical o...\",\n \"Title: Cognitive relay networks with energy and mutual-information accumulation\\nYear: 2018\\n\\nAbstract: Cognitive radio networks, a.k.a. dynamic spectrum access networks, offer a promising solution to the problems of spectrum scarcity and under-utilization. In this paper, we consider two single-user links: primary and secondary links. To increase secondary user (SU) transmission opportunities and increase primary user (PU) throughput, we consider a cognitive relay network where a SU relays PU packets that are unsuccessfully received at the primary receiver (PR). At the PR side, two protocols are suggested: i) energy accumulation (EA), and ii) mutual-information accumulation (MIA). The average stable throughput of the secondary link is derived under these protocols for a specific throughput selected by the primary link. Results show that EA and MIA can significantly improve the secondary throughput compared with the no accumulation scenario, especially under extreme environment.\",\n \"Title: High-Rate Ultrasonic Through-Wall Communications Using MIMO-OFDM.\\nYear: 2018\\n\\nAbstract: This paper investigates methods to achieve high-rate data transmission through metallic barriers using ultrasound. Multiple-input-multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM) is employed in conjunction with interference mitigation techniques to reduce throughput-limiting crosstalk. Several crosstalk mitigation strategies are investigated and their theoretical and practica...\",\n \"Title: Brain-Inspired Wireless Communications: Where Reservoir Computing Meets MIMO-OFDM.\\nYear: 2018\\n\\nAbstract: Reservoir computing (RC) is a class of neuromorphic computing approaches that deals particularly well with time-series prediction tasks. It significantly reduces the training complexity of recurrent neural networks and is also suitable for hardware implementation whereby device physics are utilized in performing data processing. In this paper, the RC concept is applied to detecting a transmitted s...\",\n \"Title: Multi-Cell Multi-User Massive FD-MIMO: Downlink Precoding and Throughput Analysis.\\nYear: 2019\\n\\nAbstract: In this paper, downlink (DL) precoding and power allocation strategies are identified for a time-division-duplex multi-cell multi-user massive full-dimension MIMO network. Utilizing channel reciprocity, DL channel state information feedback is eliminated and the DL multi-user MIMO precoding is linked to the uplink (UL) direction of arrival (DoA) estimation through the estimation of signal paramete...\",\n \"Title: Editorial: Booming of Neural Networks and Learning Systems.\\nYear: 2019\\n\\nAbstract: As you open this January issue of the IEEE Transactions on Neural Networks and Learning Systems (TNNLS), I hope everyone enjoyed a great holiday season and is excited for the new year of 2019. I am very delighted and honored to report several key metrics of IEEE TNNLS to the community.\",\n \"Title: M: N Object matching on multiscale datasets based on MBR combinatorial optimization algorithm and spatial district.\\nYear: 2018\\n\\nAbstract: Object matching is critical for updating, maintaining, integrating, and quality assessing spatial data. However, matching data are often obtained from different sources and have problems of positional discrepancy and different levels of detail. To resolve these problems, this article presents a multiscale polygonal object-matching approach, called the minimum bounding rectangle combinatorial optimization (MBRCO) with spatial district (SD). This method starts with the MBRCO algorithm and its enhancement using the SD to find corresponding MBRs of one-to-one, one-to-many, and many-to-many matching pairs. Then, it aligns the MBRs of the matching pairs to identify object-matching pairs, which are evaluated using a matching criterion to find geometrically corresponding objects. Our approach was experimentally validated using two topographical datasets at 1:2k and 1:10k. The proposed approach outperforms the common two-way area overlap method and another method based on the contextual information and relaxation labeling algorithm. The proposed method achieved accurate aggregation of the many-to-many matching pairs under the positional discrepancy scenario.\",\n \"Title: Big Data Meet Cyber-Physical Systems: A Panoramic Survey.\\nYear: 2018\\n\\nAbstract: The world is witnessing an unprecedented growth of cyber-physical systems (CPS), which are foreseen to revolutionize our world via creating new services and applications in a variety of sectors, such as environmental monitoring, mobile-health systems, intelligent transportation systems, and so on. The information and communication technology sector is experiencing a significant growth in data traffic, driven by the widespread usage of smartphones, tablets, and video streaming, along with the significant growth of sensors deployments that are anticipated in the near future. It is expected to outstandingly increase the growth rate of raw sensed data. In this paper, we present the CPS taxonomy via providing a broad overview of data collection, storage, access, processing, and analysis. Compared with other survey papers, this is the first panoramic survey on big data for CPS, where our objective is to provide a panoramic summary of different CPS aspects. Furthermore, CPS requires cybersecurity to protect them against malicious attacks and unauthorized intrusion, which become a challenge with the enormous amount of data that are continuously being generated in the network. Thus, we also provide an overview of the different security solutions proposed for CPS big data storage, access, and analytics. We also discuss big data meeting green challenges in the contexts of CPS.\",\n \"Title: Energy Consumption vs. Bit Rate Analysis Toward Massive MIMO Systems\\nYear: 2018\\n\\nAbstract: In this paper, we provide a comprehensive study and comparison of the impact of both multiple-input multiple-output (MIMO) and massive MIMO techniques, at the base station (BS), on the energy consumption versus bit rate performance of a multi-antenna wireless handset. Both spatial diversity and spatial multiplexing (SM) are examined and compared for both known and unknown channel state information (CSI) at the transmitter. For the diversity case, our results show that for a BS with four or more receive antennas, there is little to be gained in terms of energy efficiency at the wireless handset by having more than one transmit antenna. For the SMcase with conventional MIMO, the bit rate increases linearly with N\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">t</inf>\\n at the cost of additional energy consumption at the handset due to the absence of diversity gain. For massive MIMO, however, the excess receive antennas provide a diversity gain in a SM scheme thus allowing a high bit rate without sacrificing energy efficiency at the handset and even with no needs of CSI knowledge.\",\n \"Title: On the Achievable Transmission Capacity of Secrecy-Based D2D Cellular Networks.\\nYear: 2016\\n\\nAbstract: Device-to-Device (D2D) communication is one of the key technologies to get to very high data rates in future 5G networks through offloading part of the cellular traffic onto D2D networks. While extensive research is targeted on addressing the many challenges D2D brings along in cellular networks, security issues have not gained much attention, especially that the direct connections between proximity devices are more vulnerable to security threats, which in turn deteriorate users' experience. In this paper, we consider a D2D communication overheard by eavesdroppers in an underlay cellular network, where D2D users access a proportion of the spectrum occupied by cellular users. To mitigate the potential security threats, we turn towards a lightweight low-complexity approach by exploiting the physical characteristics of the wireless channels. Using tools from stochastic geometry, we derive the D2D transmission region and the average transmit power that guarantee a minimum secrecy rate and a target outage probability. Results reveal that when offloading less cellular traffic onto D2D links, the large cellular interference can be exploited to protect D2D links from eavesdroppers. On the other hand, with aggressive D2D offloading, D2D users can achieve a much higher secrecy capacity due to significantly reducing the distances between them.\",\n \"Title: Angle and Delay Estimation for 3-D Massive MIMO/FD-MIMO Systems Based on Parametric Channel Modeling.\\nYear: 2017\\n\\nAbstract: In order to meet the challenge of increasing data-rate demand as well as the form factor limitation of the base station (BS), 3-D massive multiple-input multiple-output (MIMO) technology has been introduced as one of the enabling technologies for fifth generation mobile cellular systems. In 3-D massive MIMO systems, a BS will rely on the uplink sounding signals from mobile stations to figure out t...\",\n \"Title: A Physical Layer Security Scheme for Mobile Health Cyber-Physical Systems.\\nYear: 2018\\n\\nAbstract: Mobile health (m-Health) is one potential application of cyber-physical systems, where biomedical sensors and mobile devices interact tightly together to transmit medical data to an m-Health server. In this paper, we consider a three-tier hierarchical m-Health system: 1) the sensor network tier capturing vital signals; 2) the mobile computing network tier processing and routing the sensed data to ...\",\n \"Title: Improving the Coverage and Spectral Efficiency of Millimeter-Wave Cellular Networks Using Device-to-Device Relays.\\nYear: 2018\\n\\nAbstract: The susceptibility of millimeter waveform propagation to blockages limits the coverage of millimeter-wave (mmWave) signals. To overcome blockages, we propose to leverage two-hop device-to-device (D2D) relaying. Using stochastic geometry, we derive expressions for the downlink coverage probability of relay-assisted mmWave cellular networks when the D2D links are implemented in either uplink mmWave ...\",\n \"Title: Delay-Sensitive Communications Over IR-HARQ: Modulation, Coding Latency, and Reliability\\nYear: 2019\\n\\nAbstract: With the growing popularity of delay-sensitive applications (e.g., real-time conversational video, online gaming, and augmented reality) and future trends toward ultra-reliable low-latency communications such as the tactile Internet, performance analysis of wireless systems under the finite code blocklength constraint becomes extremely important. In this paper, we investigate the maximum achievable throughput of incremental redundancy-hybrid automatic repeat request (IR-HARQ) over the (correlated) Rayleigh fading channel under finite blocklength and delay-violation probability constraints as a function of the modulation scheme. The maximum number of HARQ rounds together with the transport block size specifies the underlying coding latency of the IR-HARQ scheme. A framework, namely the HARQ Markov model (HARQ-MM), is introduced to track the throughput and the probability of error of IR-HARQ over the Rayleigh fading channel as a function of the modulation scheme. The dispersion of parallel additive white Gaussian noise channels with finite input alphabets (e.g., pulse amplitude modulation) is analytically characterized. It is used to identify the state transition probabilities of the underlying HARQ-MM. An algorithm is developed to efficiently compute the steady-state distribution of the HARQ-MM. Extensive performance evaluation is conducted, which shows a good match between the throughput performance characterized by the theoretical framework and that achieved by the practical channel codes.\",\n \"Title: Green Massive Traffic Offloading for Cyber-Physical Systems over Heterogeneous Cellular Networks\\nYear: 2019\\n\\nAbstract: While the number of things is growing accompanied with an explosive increase in wireless traffic, network providers are facing a set of challenges, especially that the massive number of devices are expected to communicate over the current cellular networks. In an attempt to relieve network congestion and increase throughput, we turn toward cell shrinking and offloading, a key technology in future 5G networks. Using this potential solution, we are mainly targeting two important issues: i) enabling cyber-physical systems (CPS) communications over cellular networks to provide CPS with several benefits such as ubiquitous coverage, global connectivity, reliability and security; and ii) offloading a proportion of CPS traffic to small cells, which in tun increases the throughput of macrocells, and frees more network resources to other users. Using stochastic geometry, we present an analysis on CPS offloading rate and achievable throughput when small cells base stations (SCBSs) are powered by solar energy. The solar energy harvesting allows SCBSs to offset the costs of serving CPS devices. Our results show the potential benefits for both macrocells and small cells in terms of minimum achievable throughput when the CPS offloading rate is high.\",\n \"Title: Enhancing Communication-Based Train Control Systems Through Train-to-Train Communications\\nYear: 2019\\n\\nAbstract: High reliability and low latency are crucial for urban rail transits. In this paper, we introduce communication strategies for communication-based train control (CBTC) systems using long-term evolution for metro (LTE-M) to improve the reliability and latency. To be specific, the FlashLinQ-based Train-to-Train (T2T) communication schemes are introduced considering both the transmission delay and the packet drop. The quantified resilience is also introduced as a system metric to evaluate the preservation and recovery performance of CBTC systems. First, a novel urban rail transit wireless communication model is established using FlashLinQ-based T2T communications. Then, we introduce a novel cognitive control scheme based on LTE-M with T2T communication to enhance the quality of service and the resilience of multi-train CBTC systems. In the introduced scheme, Q-learning is used to generate optimal control strategies considering both wireless communication parameters adaption and train control parameters. Extensive simulations are conducted and the results show that the resilience of CBTC systems can be enhanced using the introduced scheme. Furthermore, using the introduced scheme, not only the gaps in optimal velocity versus distance curve are smaller, but also the unplanned traction and breaking are reduced as well.\",\n \"Title: Downlink Resource Allocation in Cell-Free Massive MIMO Systems\\nYear: 2019\\n\\nAbstract: Cell-free Massive Multiple-Input Multiple-Output (MIMO) is introduced as a promising network architecture for the upcoming fifth-generation (5G) wireless communication networks. It enhances user experience and improves the overall system performance by providing huge throughput and coverage probability to all users throughout a system. In this paper, a resource allocation problem is studied for downlink cell-free massive MIMO networks, where each access point (AP) serves a cluster of user equipment (UE). Transmit precoding and power allocation are linked to the underlying max-min scheduling to ensure uniform and excellent service throughout the coverage area. Due to the coupled interference among UEs, the resulting max-min resource allocation optimization problem becomes non-convex. We demonstrate the uplink-downlink duality and propose an iterative algorithm which solves the primal downlink problem efficiently. By utilizing the max-min beam former and taking the channel estimation error into account, we further derive the capacity lower bound of the underlying cell-free massive MIMO network. The performance of the introduced scheme is also investigated through simulations. Numerical results show the efficiency of the introduced algorithm.\",\n \"Title: Distributive Dynamic Spectrum Access Through Deep Reinforcement Learning: A Reservoir Computing-Based Approach.\\nYear: 2019\\n\\nAbstract: Dynamic spectrum access (DSA) is regarded as an effective and efficient technology to share radio spectrum among different networks. As a secondary user (SU), a DSA device will face two critical problems: 1) avoiding causing harmful interference to primary users (PUs) and 2) conducting effective interference coordination with other SUs. These two problems become even more challenging for a distrib...\",\n \"Title: QoS-Aware D2D Cellular Networks with Spatial Spectrum Sensing: A Stochastic Geometry View\\nYear: 2019\\n\\nAbstract: Spectrum access and interference management are amongst the most challenging issues in device-to-device (D2D) cellular networks. In order to address these issues, this paper introduces spatial spectrum sensing (SSS) for D2D cellular networks to facilitate cellular spectrum sharing by D2D users while providing a quality of service guarantee for cellular users. In order to assess the performance of ...\",\n \"Title: Content-Based User Association and MIMO Operation over Cached Cloud-RAN Networks.\\nYear: 2019\\n\\nAbstract: Cloud radio access network (Cloud-RAN) has been introduced to support ever-growing end-users' needs. To reduce the backhaul traffic and aid coordinated multi-point (CoMP) transmission, base station (BS)-level caching technique can be utilized, where popular contents are pre-fetched at each BS. In this paper, multiple-input-multiple-output (MIMO) operation and user association policy are linked to the underlying cache placement strategy to ensure a good trade-off between load balancing and backhaul traffic taking into account the underlying wireless channel and the finite cache capacity at BSs. Due to the coupled interference among mobile stations, the binary nature of the underlying cache placement and user association matrices, the resulting mixed-timescale mixed integer optimization problem is nonconvex and NP-hard. To solve this problem, we decompose the joint optimization problem into a long-term content placement sub-problem and a short-term content delivery sub-problem. A novel iterative algorithm is introduced by leveraging the alternating direction method of multipliers together with a stochastic parallel successive convex approximation-based algorithm. The introduced scheme enables all BSs to update their optimization variables in parallel by solving a sequence of convex subproblems. Simulation evaluation demonstrates the efficiency of our strategy.\",\n \"Title: An Adaptive Capsule Network For Hyperspectral Remote Sensing Classification\\nYear: 2021\\n\\nAbstract: The capsule network (Caps) is a novel type of neural network that has great potential for the classification of hyperspectral remote sensing. However, the Caps suffers from the issue of gradient vanishing. To solve this problem, a powered activation regularization based adaptive capsule network (PAR-ACaps) was proposed for hyperspectral remote sensing classification, in which an adaptive routing algorithm without iteration was applied to amplify the gradient, and the powered activation regularization method was used to learn the sparser and more discriminative representation. The classification performance of PAR-ACaps was evaluated using two public hyperspectral remote sensing datasets, i.e., the Pavia University (PU) and Salinas (SA) datasets. The average overall classification accuracy (OA) of PAR-ACaps with shallower architecture was measured and compared with those of the benchmarks, including random forest (RF), support vector machine (SVM), 1-dimensional convolutional neural network (1DCNN), two-dimensional convolutional neural network (CNN), three-dimensional convolutional neural network (3DCNN), Caps, and the original adaptive capsule network (ACaps) with comparable network architectures. The OA of PAR-ACaps for PU and SA datasets was 99.51% and 94.52%, respectively, which was higher than those of benchmarks. Moreover, the classification performance of PAR-ACaps with relatively deeper neural architecture (four and six convolutional layers in the feature extraction stage) was also evaluated to demonstrate the effectiveness of gradient amplification. As shown in the experimental results, the classification performance of PAR-ACaps with relatively deeper neural architecture for PU and SA datasets was also superior to 1DCNN, CNN, 3DCNN, Caps, and ACaps with comparable neural architectures. Additionally, the training time consumed by PAR-ACaps was significantly lower than that of Caps. The proposed PAR-ACaps is, therefore, recommended as an effective alternative for hyperspectral remote sensing classification.\",\n \"Title: Cooperative Caching in HetNets With Mutual Information Accumulation\\nYear: 2021\\n\\nAbstract: Caching is a promising technique in the next generation cellular network, reducing backhaul traffic while improving network efficiency. In this letter, we introduce a cache-enabled small base station cooperative transmission scheme while considering the macro base station (MBS) silence and mutual information accumulation (MIA). A tractable analytical framework for characterizing the successful transmission probability (STP) of the introduced scheme is described. The STP is maximized by optimizing the caching placement policy based on a constrained cross entropy optimization algorithm. Simulation results demonstrate that the proposed SBS cooperative transmission with MBS silence and MIA achieves higher STP than other compared schemes.\",\n \"Title: Interference Alignment Meets Multi-Cell Multi-User Massive FD-MIMO Systems in DoA-Based Precoding\\nYear: 2021\\n\\nAbstract: In this paper, a downlink (DL) precoding scheme is introduced for time-division-duplex (TDD) multi-cell multi-user 3D massive MIMO/full-dimension MIMO (FD-MIMO) systems. A pre-beamformer based on uplink direction-of-arrival (DoA) is incorporated with interference alignment (IA) scheme to provide more degrees of freedom for each cell. We analyze the feasible conditions of applying IA schemes and pr...\",\n \"Title: Adversarial Classification of the Attacks on Smart Grids Using Game Theory and Deep Learning\\nYear: 2021\\n\\nAbstract: ABSTRACTSmart grids are vulnerable to cyber-attacks. This paper proposes a game-theoretic approach to evaluate the variations caused by an attacker on the power measurements. Adversaries can gain financial benefits through the manipulation of the meters of smart grids. On the other hand, there is a defender that tries to maintain the accuracy of the meters. A zero-sum game is used to model the interactions between the attacker and defender. In this paper, two different defenders are used and the effectiveness of each defender in different scenarios is evaluated. Multi-layer perceptrons (MLPs) and traditional state estimators are the two defenders that are studied in this paper. The utility of the defender is also investigated in adversary-aware and adversary-unaware situations. Our simulations suggest that the utility which is gained by the adversary drops significantly when the MLP is used as the defender. It will be shown that the utility of the defender is variant in different scenarios, based on the defender that is being used. In the end, we will show that this zero-sum game does not yield a pure strategy, and the mixed strategy of the game is calculated.\",\n \"Title: Trade-Offs in Reliability, Latency, and Energy for Random Network Coding-Enabled Networks\\nYear: 2021\\n\\nAbstract: In random network coding (RNC)-enabled networks, a sufficient number of linearly independent encoded packets, i.e., generations, is guaranteed at the cost of high latency and energy consumption at the transmitter. This letter aims to reduce the weighted sum of latency and energy while guaranteeing a targeted successful transmission probability, which is defined as the probability that the RNC-enabled network has sufficient generations when the transmitter receives a required number of acknowledgements (ACKs) feedback. An analytical framework and a deep learning-based method are developed. Results show that the latency and energy consumption are reduced by jointly optimizing the required number of ACKs and the transmit power at the transmitter.\",\n \"Title: Multiagent Reinforcement Learning Meets Random Access in Massive Cellular Internet of Things\\nYear: 2021\\n\\nAbstract: Internet of Things (IoT) has attracted considerable attention in recent years due to its potential of interconnecting a large number of heterogeneous wireless devices. However, it is usually challenging to provide reliable and efficient random access control when massive IoT devices are trying to access the network simultaneously. In this article, we investigate methods to introduce intelligent ra...\",\n \"Title: Learning to Equalize OTFS\\nYear: 2022\\n\\nAbstract: Orthogonal Time Frequency Space (OTFS) is a novel framework that processes modulation symbols via a time-independent channel characterized by the delay-Doppler domain. The conventional waveform, orthogonal frequency division multiplexing (OFDM), requires tracking frequency selective fading channels over the time, whereas OTFS benefits from full time-frequency diversity by leveraging appropriate equalization techniques. In this paper, we consider a neural network-based supervised learning framework for OTFS equalization. Learning of the introduced neural network is conducted in each OTFS frame fulfilling an online learning framework: the training and testing datasets are within the same OTFS-frame over the air. Utilizing reservoir computing, a special recurrent neural network, the resulting one-shot online learning is sufficiently flexible to cope with channel variations among different OTFS frames (e.g., due to the link/rank adaptation and user scheduling in cellular networks). The proposed method does not require explicit channel state information (CSI) and simulation results demonstrate a lower bit error rate (BER) than conventional equalization methods in the low signal-to-noise (SNR) regime under large Doppler spreads. When compared with its neural network-based counterparts for OFDM, the introduced approach for OTFS will lead to a better tradeoff between the processing complexity and the equalization performance.\",\n \"Title: Computing over Space-Air-Ground Integrated Networks: Challenges and Opportunities\\nYear: 2021\\n\\nAbstract: Space-air-ground integrated networks (SAGINs) have gained significant attention and become a promising architecture for ubiquitous connectivity for 5G-Advanced and 6G, enabling the integration of satellite networks, aerial networks, and terrestrial networks. This integration brings tremendous communication benefits, such as non-terrestrial networks, seamless global coverage, high flexibility, and augmented system capacity. Meanwhile, computing capability becomes an indispensable part of the SAGIN ecosystem. In SAGINs, limited and unbalanced computation and communication resources of different network segments make it challenging to provide strict quality-of-service (QoS) guarantees for specific traffic (e.g., delay-sensitive traffic and outage-sensitive traffic). To fully utilize available system resources in SAGINs, cooperative computing among different network segments is a promising technology. This article presents the fundamentals and applications of computing over SAGINs by introducing the system architecture and explaining the potential technical issues related to cooperative computing. Furthermore, the potential for cooperative computing over SAGINs is showcased with a preliminary performance evaluation. Finally, future research opportunities are discussed.\",\n \"Title: Deep Learning-Assisted Energy-Efficient Task Offloading in Vehicular Edge Computing Systems\\nYear: 2021\\n\\nAbstract: In this paper, we study an energy-efficient computation offloading for vehicular edge computing systems, where multiple roadside units assist vehicular users to offload computation tasks to edge servers. Our goal is to minimize the users’ energy consumption by optimizing user association, data partition, transmit power, and computation resources, subject to the constraints of partial tasks offload...\",\n \"Title: RC-Struct: A Structure-Based Neural Network Approach for MIMO-OFDM Detection\\nYear: 2022\\n\\nAbstract: In this paper, we introduce a structure-based neural network architecture, namely RC-Struct, for MIMO-OFDM symbol detection. The RC-Struct exploits the temporal structure of the MIMO-OFDM signals through reservoir computing (RC). A binary classifier leverages the repetitive constellation structure in the system to perform multi-class detection. The incorporation of RC allows the RC-Struct to be learned in a purely online fashion with extremely limited pilot symbols in each OFDM subframe. The binary classifier enables the efficient utilization of the precious online training symbols and allows an easy extension to high-order modulations without a substantial increase in complexity. Experiments show that the introduced RC-Struct outperforms both the conventional model-based symbol detection approaches and the state-of-the-art learning-based strategies in terms of bit error rate (BER). The advantages of RC-Struct over existing methods become more significant when rank and link adaptation are adopted. The introduced RC-Struct sheds light on combining communication domain knowledge and learning-based receive processing for 5G/5G-Advanced and Beyond.\",\n \"Title: A Cost-Efficient Digital ESN Architecture on FPGA for OFDM Symbol Detection\\nYear: 2021\\n\\nAbstract: AbstractThe echo state network (ESN) is a recently developed machine-learning paradigm whose processing capabilities rely on the dynamical behavior of recurrent neural networks. Its performance outperforms traditional recurrent neural networks in nonlinear system identification and temporal information processing applications. We design and implement a cost-efficient ESN architecture on field-programmable gate array (FPGA) that explores the full capacity of digital signal processor blocks on low-cost and low-power FPGA hardware. Specifically, our scalable ESN architecture on FPGA exploits Xilinx DSP48E1 units to cut down the need of configurable logic blocks. The proposed architecture includes a linear combination processor with negligible deployment of configurable logic blocks and a high-accuracy nonlinear function approximator. Our work is verified with the prediction task on the classical NARMA dataset and a symbol detection task for orthogonal frequency division multiplexing systems using a wireless communication testbed built on a software-defined radio platform. Experiments and performance measurement show that the new ESN architecture is capable of processing real-world data efficiently for low-cost and low-power applications.\",\n \"Title: Optimizing Number, Placement, and Backhaul Connectivity of Multi-UAV Networks\\nYear: 2022\\n\\nAbstract: Multi unmanned aerial vehicle (UAV) network is a promising solution to providing wireless coverage to ground users in challenging rural areas (such as Internet of Things (IoT) devices in farmlands), where the traditional cellular networks are sparse or unavailable. A key challenge in such networks is the 3-D placement of all UAV base stations (BSs) such that the formed multi-UAV network: 1) utilizes a minimum number of UAVs while ensuring—2) backhaul connectivity directly (or via other UAVs) to the nearby terrestrial BS; and 3) wireless coverage to all ground users in the area of operation. This joint backhaul-and-coverage-aware drone deployment (BoaRD) problem is largely unaddressed in the literature and, thus, is the focus of this article. We first formulate the BoaRD problem as integer linear programming (ILP). However, the problem is NP-hard and, therefore, we propose a low complexity algorithm with a provable performance guarantee to solve the problem efficiently. Our simulation study shows that the Proposed algorithm performs very close to that of the Optimal algorithm (solved using ILP solver) for smaller scenarios, where the area size and the number of users are relatively small. For larger scenarios, where the area size and the number of users are relatively large, the proposed algorithm greatly outperforms the baseline approaches—Backhaul-aware Greedy and random algorithm, respectively, by up to 17% and 95% in utilizing fewer UAVs while ensuring 100% ground-user coverage and backhaul connectivity for all deployed UAVs across all considered simulation setting.\",\n \"Title: UAV Swarm-Enabled Aerial Reconfigurable Intelligent Surface (SARIS)\\nYear: 2021\\n\\nAbstract: Reconfigurable intelligent surface (RIS) offers tremendous spectrum and energy efficiency in wireless networks by adjusting the amplitudes and/or phases of passive reflecting elements to optimize signal reflection. With the agility and mobility of unmanned aerial vehicles (UAVs), RIS can be mounted on UAVs to enable three-dimensional signal reflection. Compared to the conventional terrestrial RIS ...\",\n \"Title: A Hybrid FPGA-ASIC Delayed Feedback Reservoir System to Enable Spectrum Sensing/Sharing for Low Power IoT Devices ICCAD Special Session Paper\\nYear: 2021\\n\\nAbstract: The delayed feedback reservoir (DFR) network is a delay-dynamic architecture that incorporates time in its training and inference. This quality enables DFR networks to proficiently model time series in a scalable architecture with only one nonlinear neuron. Previous studies have highlighted the accuracy and energy efficiency of DFR networks in ASIC implementations; however, these approaches are li...\",\n \"Title: Resource Allocation for D2D Cellular Networks With QoS Constraints: A DC Programming- Based Approach\\nYear: 2022\\n\\nAbstract: Device-to-device (D2D) communications provide efficient ways to increase spectrum utilization ratio with reduced power consumption for proximity wireless applications. In this paper, we investigate resource allocation strategies for D2D communications underlaying cellular networks. To be specific, we study the centralized resource allocation algorithm for controlling transmit powers of the underlying D2D pairs in order to maximize the weighted sum-rate while guaranteeing the quality of service (QoS) requirements for both D2D pairs and cellular users (CUs). A novel DC (difference of convex function) programming-based method, called alternative DC (ADC) programming, is introduced to effectively solve this complicated resource allocation problem. Through updating each D2D pair's power alternatively, the QoS requirement for each D2D pair can be solvable and incorporated systematically to the introduced ADC programming framework. The simulation results show that the introduced ADC programming achieves the highest weighted sum-rate compared to the state-of-the-art methods while ensuring that the QoS of each D2D pair and CU are satisfied.\",\n \"Title: Reservoir Computing Meets Extreme Learning Machine in Real-Time MIMO-OFDM Receive Processing\\nYear: 2022\\n\\nAbstract: In this paper, we consider a real-time deep learning-based symbol detection approach for MIMO-OFDM systems. To exploit the temporal correlation of the wireless channel and the time-frequency structure of OFDM signals, a recurrent neural network (RNN) with deep feedforward output layers is introduced, where the recurrent layers and feedforward output layers are designed to process time-domain and frequency-domain information respectively. Reservoir computing (RC), a special type of RNN, and extreme learning machine (ELM), a special type of feedforward neural network, are chosen as the corresponding building blocks to facilitate over-the-air training. An online training loss objective is introduced to recursively update the neural weights in real-time. We believe this is the first work in the literature to realize real-time machine learning for MIMO-OFDM symbol detection, i.e., conducting NN-based symbol detection on an OFDM symbol basis. We demonstrate that (1) the \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">IEEE</i>\\n standardized WiFi training sequence can be directly applied as the real-time training sequence (2) the symbol detection performance can be further improved by using our theoretically derived pilot pattern. Evaluation results show that our RC-ELM-based symbol detection method outperforms traditional model-based techniques as well as state-of-the-art learning-based approaches in highly dynamic channel environments for real-time symbol detection.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":119,"string":"119"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":262,"string":"262"}}},{"rowIdx":263,"cells":{"question_id":{"kind":"string","value":"Eike Kiltz"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Concrete Treatment of Fiat-Shamir Signatures in the Quantum Random-Oracle Model.\" using the following items: Fiat-Shamir transform, QROM, UF-NMA, lossy identification, Dilithium signature scheme."},"answer":{"kind":"string","value":"The Fiat-Shamir transform is a technique for combining a hash function and an identification scheme to produce a digital signature scheme. The resulting scheme is known to be secure in the random oracle model (ROM), which does not, however, imply security in the scenario where the adversary also has quantum access to the oracle. The goal of this current paper is to create a generic framework for constructing tight reductions in the QROM from underlying hard problems to Fiat-Shamir signatures. Our generic reduction is composed of two results whose proofs, we believe, are simple and natural. We first consider a security notion (UFNMA) in which the adversary obtains the public key and attempts to create a valid signature without accessing a signing oracle. We give a tight reduction showing that deterministic signatures (i.e., ones in which the randomness is derived from the message and the secret key) that are UFNMA secure are also secure under the standard chosen message attack (UF-CMA) security definition. Our second result is showing that if the identification scheme is \"lossy\", as defined in (Abdalla et al. Eurocrypt 2012), then the security of the UF-NMA scheme is tightly based on the hardness of distinguishing regular and lossy public keys of the identification scheme. This latter distinguishing problem is normally exactly the definition of some presumably-hard mathematical problem. The combination of these components gives our main result. As a concrete instantiation of our framework, we modify the recent lattice-based Dilithium digital signature scheme (Ducas et al., TCHES 2018) so that its underlying identification scheme admits lossy public keys. The original Dilithium scheme, which is proven secure in the classical ROM based on standard lattice assumptions, has 1.5 KB public keys and 2.7 KB signatures. The new scheme, which is tightly based on the hardness of the Module-LWE problem in the QROM using our generic reductions, has 7.7 KB public keys and 5.7 KB signatures for the same security level. Furthermore, due to our proof of equivalence between the UF-NMA and UFCMA security notions of deterministic signature schemes, we can formulate a new non-interactive assumption under which the original Dilithium signature scheme is also tightly secure in the QROM."},"correct_answer":{"kind":"string","value":"The Fiat-Shamir transform is a technique for combining a hash function and an identification scheme to produce a digital signature scheme. The resulting scheme is known to be secure in the random oracle model (ROM), which does not, however, imply security in the scenario where the adversary also has quantum access to the oracle. The goal of this current paper is to create a generic framework for constructing tight reductions in the QROM from underlying hard problems to Fiat-Shamir signatures. Our generic reduction is composed of two results whose proofs, we believe, are simple and natural. We first consider a security notion (UFNMA) in which the adversary obtains the public key and attempts to create a valid signature without accessing a signing oracle. We give a tight reduction showing that deterministic signatures (i.e., ones in which the randomness is derived from the message and the secret key) that are UFNMA secure are also secure under the standard chosen message attack (UF-CMA) security definition. Our second result is showing that if the identification scheme is \"lossy\", as defined in (Abdalla et al. Eurocrypt 2012), then the security of the UF-NMA scheme is tightly based on the hardness of distinguishing regular and lossy public keys of the identification scheme. This latter distinguishing problem is normally exactly the definition of some presumably-hard mathematical problem. The combination of these components gives our main result. As a concrete instantiation of our framework, we modify the recent lattice-based Dilithium digital signature scheme (Ducas et al., TCHES 2018) so that its underlying identification scheme admits lossy public keys. The original Dilithium scheme, which is proven secure in the classical ROM based on standard lattice assumptions, has 1.5 KB public keys and 2.7 KB signatures. The new scheme, which is tightly based on the hardness of the Module-LWE problem in the QROM using our generic reductions, has 7.7 KB public keys and 5.7 KB signatures for the same security level. Furthermore, due to our proof of equivalence between the UF-NMA and UFCMA security notions of deterministic signature schemes, we can formulate a new non-interactive assumption under which the original Dilithium signature scheme is also tightly secure in the QROM."},"documents":{"kind":"list like","value":["Title: Certifying RSA\nYear: 2012\n\nAbstract: We propose an algorithm that, given an arbitrary N of unknown factorization and prime e ≥ N1/4+ε, certifies whether the RSA function RSAN,e(x) :=xe mod N defines a permutation over ℤ*N or not. The algorithm uses Coppersmith's method to find small solutions of polynomial equations and runs in time O(ε−8 log2N). Previous certification techniques required eN.","Title: Message authentication, revisited\nYear: 2012\n\nAbstract: Traditionally, symmetric-key message authentication codes (MACs) are easily built from pseudorandom functions (PRFs). In this work we propose a wide variety of other approaches to building efficient MACs, without going through a PRF first. In particular, unlike deterministic PRF-based MACs, where each message has a unique valid tag, we give a number of probabilistic MAC constructions from various other primitives/assumptions. Our main results are summarized as follows: — We show several new probabilistic MAC constructions from a variety of general assumptions, including CCA-secure encryption, Hash Proof Systems and key-homomorphic weak PRFs. By instantiating these frameworks under concrete number theoretic assumptions, we get several schemes which are more efficient than just using a state-of-the-art PRF instantiation under the corresponding assumption. — For probabilistic MACs, unlike deterministic ones, unforgeability against a chosen message attack (uf-cma ) alone does not imply security if the adversary can additionally make verification queries (uf-cmva ). We give an efficient generic transformation from any uf-cma secure MAC which is \"message-hiding\" into a uf-cmva secure MAC. This resolves the main open problem of Kiltz et al. from Eurocrypt'11; By using our transformation on their constructions, we get the first efficient MACs from the LPN assumption. — While all our new MAC constructions immediately give efficient actively secure, two-round symmetric-key identification schemes, we also show a very simple, three-round actively secure identification protocol from any weak PRF. In particular, the resulting protocol is much more efficient than the trivial approach of building a regular PRF from a weak PRF.","Title: Complexity theoretic aspects of some cryptographic functions\nYear: 2003\n\nAbstract: In this work, we are interested in non-trivial upper bounds on the spectral norm of binary matrices M from {-1, 1}N × N. It is known that the distributed Boolean function represented by M is hard to compute in various restricted models of computation if the spectral norm is bounded from above by N1-Ɛ, where Ɛ 0 denotes a fixed constant. For instance, the size of a two-layer threshold circuit (with polynomially bounded weights for the gates in the hidden layer, but unbounded weights for the output gate) grows exponentially fast with n:= logN. We prove sufficient conditions on M that imply small spectral norms (and thus high computational complexity in restricted models). Our general results cover specific cases, where the matrix M represents a bit (the least significant bit or other fixed bits) of a cryptographic decoding function. For instance, the decoding functions of the Pointcheval [9], the El Gamal [6], and the RSA-Paillier [2] cryptosystems can be addressed by our technique. In order to obtain our results, we make a detour on exponential sums and on spectral norms of matrices with complex entries. This method might be considered interesting in its own right.","Title: On the limitations of the spread of an IBE-to-PKE transformation\nYear: 2006\n\nAbstract: By a generic transformation by Canetti, Halevi, and Katz (CHK) every Identity-based encryption (IBE) scheme implies a chosen-ciphertext secure public-key encryption (PKE) scheme. In the same work it is claimed that this transformation maps the two existing IBE schemes to two new and different chosen-ciphertext secure encryption schemes, each with individual advantages over the other. In this work we reconsider one of the two specific instantiations of the CHK transformation (when applied to the “second Boneh/Boyen IBE scheme”). We demonstrate that by applying further simplifications the resulting scheme can be proven secure under a weaker assumption than the underlying IBE scheme. Surprisingly, our simplified scheme nearly converges to a recent encryption scheme due to Boyen, Mei, and Waters which itself was obtained from the other specific instantiation of the CHK transformation (when applied to the “first Boneh/Boyen IBE scheme”). We find this particularly interesting since the two underlying IBE schemes are completely different. The bottom line of this paper is that the claim made by Canetti, Halevi, and Katz needs to be reformulated to: the CHK transformation maps the two known IBE schemes to nearly one single encryption scheme.","Title: Cryptographic protocols from lattices\nYear: 2010\n\nAbstract: In this talk, we will introduce abstract tools and techniques for working with lattices from the perspective of a cryptographic protocol designer. We will also show how to apply these tools to yield a number of provably secure public-key primitives ranging from digital signatures and public-key encryption, to more advanced protocols such as (hierarchical) identity-based encryption.","Title: Leakage Resilient ElGamal Encryption\nYear: 2010\n\nAbstract: Blinding is a popular and well-known countermeasure to protect public-key cryptosystems against side-channel attacks. The high level idea is to randomize an exponentiation in order to prevent multiple measurements of the same operation on different data, as such measurements might allow the adversary to learn the secret exponent. Several variants of blinding have been proposed in the literature, using additive or multiplicative secret-sharing to blind either the base or the exponent. These countermeasures usually aim at preventing particular side-channel attacks (mostly power analysis) and come without any formal security guarantee. In this work we investigate to which extend blinding can provide provable security against a general class of side-channel attacks. Surprisingly, it turns out that in the context of public-key encryption some blinding techniques are more suited than others. In particular, we consider a multiplicatively blinded version of ElGamal public-key encryption where we prove that the scheme, instantiated over bilinear groups of prime order p (where p 1 is not smooth) is leakage resilient in the generic-group model. Here we consider the model of chosen-ciphertext security in the presence of continuous leakage, i.e., the scheme remains chosen-ciphertext secure even if with every decryption query the adversary can learn a bounded amount (roughly log(p)/2 bits) of arbitrary, adversarially chosen information about the computation. we conjecture that the scheme, instantiated over arbitrary groups of prime order p (where p 1 is not smooth) is leakage resilient. Previous to this work no encryption scheme secure against continuous leakage was known. Constructing a scheme that can be proven, secure in the standard model remains an interesting open problem.","Title: Lapin: an efficient authentication protocol based on Ring-LPN\nYear: 2012\n\nAbstract: We propose a new authentication protocol that is provably secure based on a ring variant of the learning parity with noise (LPN) problem. The protocol follows the design principle of the LPN-based protocol from Eurocrypt'11 (Kiltz et al.), and like it, is a two round protocol secure against active attacks. Moreover, our protocol has small communication complexity and a very small footprint which makes it applicable in scenarios that involve low-cost, resource-constrained devices. Performance-wise, our protocol is more efficient than previous LPN-based schemes, such as the many variants of the Hopper-Blum (HB) protocol and the aforementioned protocol from Eurocrypt'11. Our implementation results show that it is even comparable to the standard challenge-and-response protocols based on the AES block-cipher. Our basic protocol is roughly 20 times slower than AES, but with the advantage of having 10 times smaller code size. Furthermore, if a few hundred bytes of non-volatile memory are available to allow the storage of some off-line pre-computations, then the online phase of our protocols is only twice as slow as AES.","Title: Simple and efficient public-key encryption from computational diffie-hellman in the standard model\nYear: 2010\n\nAbstract: This paper proposes practical chosen-ciphertext secure public-key encryption systems that are provably secure under the computational Diffie-Hellman assumption, in the standard model. Our schemes are conceptually simpler and more efficient than previous constructions. We also show that in bilinear groups the size of the public-key can be shrunk from n to $2\\sqrt{n}$ group elements, where n is the security parameter.","Title: Threshold circuit lower bounds on cryptographic functions\nYear: 2005\n\nAbstract: In this work, we are interested in non-trivial upper bounds on the spectral norm of binary matrices M from {-1,1}^N^x^N. It is known that the distributed Boolean function represented by M is hard to compute in various restricted models of computation if the spectral norm is bounded from above by N^1^-^@?, where @?0 denotes a fixed constant. For instance, the size of a two-layer threshold circuit (with polynomially bounded weights for the gates in the hidden layer, but unbounded weights for the output gate) grows exponentially fast with n@?logN. We prove sufficient conditions on M that imply small spectral norms (and thus high computational complexity in restricted models). Our general results cover specific cases, where the matrix M represents a bit (the least significant bit or other fixed bits) of fundamental functions. Functions like the discrete multiplication and division, as well as cryptographic functions such as the Diffie-Hellman function (IEEE Trans. Inform. Theory 22(6) (1976) 644-654) and the decryption functions of the Pointcheval (Advances in Cryptology-Proceedings of EUROCRYPT '99, Lecture Notes in Computer Science, Springer, Berlin, 1999, pp. 239-254) and the El Gamal (Advances in Cryptology-CRYPTO '84, 1984, pp. 10-18) cryptosystems can be addressed by our technique. In order to obtain our results, we make a detour on exponential sums and on spectral norms of matrices with complex entries. This method might be considered interesting in its own right.","Title: Some (in)sufficient conditions for secure hybrid encryption\nYear: 2006\n\nAbstract: In hybrid public key encryption (PKE), first a key encapsulation mechanism (KEM) is used to fix a random session key that is then fed into a highly efficient data encapsulation mechanism (DEM) to encrypt the actual message. A well-known composition theorem states that if both the KEM and the DEM have a high enough level of security (i.e., security against chosen-ciphertext attacks), then so does the hybrid PKE scheme. It is not known if these strong security requirements on the KEM and DEM are also necessary, nor if such general composition theorems exist for weaker levels of security. Using six different security notions for KEMs, 10 for DEMs, and six for PKE schemes, we completely characterize in this work which combinations lead to a secure hybrid PKE scheme (by proving a composition theorem) and which do not (by providing counterexamples). Furthermore, as an independent result, we revisit and extend prior work on the relations among security notions for KEMs and DEMs.","Title: Unconditionally secure constant-rounds multi-party computation for equality, comparison, bits and exponentiation\nYear: 2006\n\nAbstract: We show that if a set of players hold shares of a value $a \\in \\mathbb{F}_p $ for some prime p (where the set of shares is written [a]p), it is possible to compute, in constant rounds and with unconditional security, sharings of the bits of a, i.e., compute sharings [a0]p, ..., [aℓ−−1]p such that ℓ = ⌈ log2p ⌉, a0,...,al−1∈{0,1} and a = ∑i=0ℓ−−1ai 2i. Our protocol is secure against active adversaries and works for any linear secret sharing scheme with a multiplication protocol. The complexity of our protocol is $\\mathcal{O}(l {\\rm log} l)$ invocations of the multiplication protocol for the underlying secret sharing scheme, carried out in $\\mathcal{O}(1)$ rounds. This result immediately implies solutions to other long-standing open problems such as constant-rounds and unconditionally secure protocols for deciding whether a shared number is zero, comparing shared numbers, raising a shared number to a shared exponent and reducing a shared number modulo a shared modulus.","Title: The Kurosawa--Desmedt key encapsulation is not chosen-ciphertext secure\nYear: 2009\n\nAbstract: At CRYPTO 2004, Kurosawa and Desmedt presented a new hybrid encryption scheme that is chosen-ciphertext (CCA2) secure in the standard model. Until now it was unknown if the key encapsulation part of the Kurosawa-Desmedt scheme by itself is still CCA2-secure or not. In this note we answer this question to the negative, namely we present a simple CCA2 attack on the Kurosawa-Desmedt key encapsulation mechanism. Our attack further supports the design paradigm of Kurosawa and Desmedt to build CCA2-secure hybrid encryption from weak key encapsulation.","Title: Secure computation of the mean and related statistics\nYear: 2005\n\nAbstract: In recent years there has been massive progress in the development of technologies for storing and processing of data. If statistical analysis could be applied to such data when it is distributed between several organisations, there could be huge benefits. Unfortunately, in many cases, for legal or commercial reasons, this is not possible. The idea of using the theory of multi-party computation to analyse efficient algorithms for privacy preserving data-mining was proposed by Pinkas and Lindell. The point is that algorithms developed in this way can be used to overcome the apparent impasse described above: the owners of data can, in effect, pool their data while ensuring that privacy is maintained. Motivated by this, we describe how to securely compute the mean of an attribute value in a database that is shared between two parties. We also demonstrate that existing solutions in the literature that could be used to do this leak information, therefore underlining the importance of applying rigorous theoretical analysis rather than settling for ad hoc techniques.","Title: Programmable Hash Functions and Their Applications\nYear: 2011\n\nAbstract: We introduce a new information-theoretic primitive called programmable hash functions (PHFs). PHFs can be used to program the output of a hash function such that it contains solved or unsolved discrete logarithm instances with a certain probability.\n This is a technique originally used for security proofs in the random oracle model. We give a variety of standard model realizations of PHFs (with different parameters).\n \n The programmability of PHFs make them a suitable tool to obtain black-box proofs of cryptographic protocols when considering\n adaptive attacks. We propose generic digital signature schemes from the strong RSA problem and from some hardness assumption\n on bilinear maps that can be instantiated with any PHF. Our schemes offer various improvements over known constructions. In\n particular, for a reasonable choice of parameters, we obtain short standard model digital signatures over bilinear maps.","Title: Chosen-ciphertext secure threshold identity-based key encapsulation without random oracles\nYear: 2006\n\nAbstract: We describe the first identity-based key encapsulation mechanism with threshold key delegation and decapsulation that is secure in the standard model against chosen-ciphertext (CCA2) attacks. Our scheme is unconditionally consistent and proved secure under the Bilinear Decisional Diffie-Hellman assumption.","Title: DDH-Like assumptions based on extension rings\nYear: 2012\n\nAbstract: We introduce and study a new type of DDH-like assumptions based on groups of prime order q . Whereas standard DDH is based on encoding elements of $\\mathbb{F}_{q}$ \"in the exponent\" of elements in the group, we ask what happens if instead we put in the exponent elements of the extension ring $R_f= \\mathbb{F}_{q}[X]/(f)$ where f is a degree-d polynomial. The decision problem that follows naturally reduces to the case where f is irreducible. This variant is called the d -DDH problem, where 1-DDH is standard DDH. We show in the generic group model that d -DDH is harder than DDH for d 1 and that we obtain, in fact, an infinite hierarchy of progressively weaker assumptions whose complexities lie \"between\" DDH and CDH. This leads to a large number of new schemes because virtually all known DDH-based constructions can very easily be upgraded to be based on d -DDH. We use the same construction and security proof but get better security and moreover, the amortized complexity (e.g, computation per encrypted bit) is the same as when using DDH. We also show that d -DDH, just like DDH, is easy in bilinear groups. We therefore suggest a different type of assumption, the d -vector DDH problems (d -VDDH), which are based on f (X )=X d , but with a twist to avoid problems with reducible polynomials. We show in the generic group model that d -VDDH is hard in bilinear groups and that the problems become harder with increasing d . We show that hardness of d -VDDH implies CCA-secure encryption, efficient Naor-Reingold style pseudorandom functions, and auxiliary input secure encryption. This can be seen as an alternative to the known family of k -LIN assumptions.","Title: Subtleties in the Definition of IND-CCA: When and How Should Challenge Decryption Be Disallowed?\nYear: 2009\n\nAbstract: IND-CCA (indistinguishability under adaptive chosen-ciphertext attacks) is a central notion of security for public-key encryption, defined and targeted in many papers. Non-triviality of the notion requires that the adversary not query the challenge ciphertext to the decryption oracle. We point out that this \\\"no-challenge-decryption\\\" condition can be formalized in several different ways and the literature is not consistent, sometimes doing it one way, sometimes another, and assuming it makes no difference. We show that the latter perception is incorrect. It does make a difference, for the resulting notions are not equivalent. Specifically, we consider four notions corresponding to whether challenge decryption is disallowed in both phases of the adversary's attack or just in the second, and, orthogonally, whether the disallowance is \\\"penalty\\\" or \\\"exclusion\\\" based. We show that the notions are not all equivalent for public-key encryption (PKE). We then show that, in contrast, they are equivalent for key-encapsulation mechanisms (KEMs). Our work shows that subtle foundational issues exist even with notions that are supposedly well-established and unambiguous, and highlights the need to be careful and precise with regard to \\\"minor\\\" definitional \\\"details\\\".","Title: Chosen-Ciphertext Secure Identity-Based Encryption in the Standard Model with short Ciphertexts\nYear: 2006\n\nAbstract: We describe a practical identity-based encryption scheme that is secure in the standard model against chosen-ciphertext (CCA2) attacks. Security is based on an assumption comparable to (but slightly stronger than) Bilinear Decisonal Die-Hellman (BDDH). A comparison shows that our construction outperforms all known identity-based encryption schemes in the standard model and its performance is even comparable with the one from the random-oracle based Boneh/Franklin IBE scheme. Our proposed IBE scheme has furthermore the property that it fulfills some notion of \"redundancy-freeness\", i.e. the encryption algorithm is not only a probabilistic injection but also a surjection. As a consequence the ciphertext overhead is nearly optimal: to encrypt k bit messages for k bit identities and with k bit randomness we get 3k bit ciphertexts to guarantee (roughly) k bits of security. Keywords: Chosen-ciphertext security, Identity-Based Encryption, Bilinear Maps.","Title: Instantiability of RSA-OAEP under chosen-plaintext attack\nYear: 2010\n\nAbstract: We show that the widely deployed RSA-OAEP encryption scheme of Bellare and Rogaway (Eurocrypt 1994), which combines RSA with two rounds of an underlying Feistel network whose hash (i.e., round) functions are modeled as random oracles, meets indistinguishability under chosen-plaintext attack (IND-CPA) in the standard model based on simple, non-interactive, and non-interdependent assumptions on RSA and the hash functions. To prove this, we first give a result on a more general notion called \"padding-based\" encryption, saying that such a scheme is IND-CPA if (1) its underlying padding transform satisfies a \"fooling\" condition against small-range distinguishers on a class of high-entropy input distributions, and (2) its trapdoor permutation is sufficiently lossy as defined by Peikert and Waters (STOC 2008). We then show that the first round of OAEP satifies condition (1) if its hash function is t-wise independent for appopriate t and that RSA satisfies condition (2) under the φ-Hiding Assumption of Cachin et al. (Eurocrypt 1999). This appears to be the first non-trivial positive result about the instantiability of RSA-OAEP. In particular, it increases our confidence that chosen-plaintext attacks are unlikely to be found against the scheme. In contrast, RSA-OAEP's predecessor in PKCS #1 v1.5 was shown to be vulnerable to such attacks by Coron et al. (Eurocrypt 2000).","Title: Secure hybrid encryption from weakened key encapsulation\nYear: 2007\n\nAbstract: We put forward a new paradigm for building hybrid encryption schemes from constrained chosen-ciphertext secure (CCCA) key-encapsulation mechanisms (KEMs) plus authenticated symmetric encryption. Constrained chosen-ciphertext security is a new security notion for KEMs that we propose. It has less demanding security requirements than standard CCCA security (since it requires the adversary to have a certain plaintext-knowledge when making a decapsulation query) yet we can prove that it is CCCA sufficient for secure hybrid encryption. Our notion is not only useful to express the Kurosawa-Desmedt public-key encryption scheme and its generalizations to hash-proof systems in an abstract KEM/DEM security framework. It also has a very constructive appeal, which we demonstrate with a new encryption scheme whose security relies on a class of intractability assumptions that we show (in the generic group model) strictly weaker than the Decision Diffie-Hellman (DDH) assumption. This appears to be the first practical public-key encryption scheme in the literature from an algebraic assumption strictly weaker than DDH.","Title: Direct chosen-ciphertext secure identity-based key encapsulation without random oracles\nYear: 2006\n\nAbstract: We describe a practical identity-based encryption scheme that is secure in the standard model against chosen-ciphertext attacks. Our construction applies ''direct chosen-ciphertext techniques'' to Waters' chosen-plaintext secure scheme and is not based on hierarchical identity-based encryption. Furthermore, we give an improved concrete security analysis for Waters' scheme. As a result, one can instantiate the scheme in smaller groups, resulting in efficiency improvements.","Title: Adaptive trapdoor functions and chosen-ciphertext security\nYear: 2010\n\nAbstract: We introduce the notion of adaptive trapdoor functions (ATDFs); roughly, ATDFs remain one-way even when the adversary is given access to an inversion oracle. Our main application is the black-box construction of chosen-ciphertext secure public-key encryption (CCA-secure PKE). Namely, we give a black-box construction of CCA-Secure PKE from ATDFs, as well as a construction of ATDFs from correlation-secure TDFs introduced by Rosen and Segev (TCC ’09). Moreover, by an extension of a recent result of Vahlis (TCC ’10), we show that ATDFs are strictly weaker than the latter (in a black-box sense). Thus, adaptivity appears to be the weakest condition on a TDF currently known to yield the first implication. We also give a black-box construction of CCA-secure PKE from a natural extension of ATDFs we call tag-based ATDFs that, when applied to our constructions of the latter from either correlation-secure TDFs, or lossy TDFs introduced by Peikert and Waters (STOC ’08), yield precisely the CCA-secure PKE schemes in these works. This helps to unify and clarify their schemes. Finally, we show how to realize tag-based ATDFs from an assumption on RSA inversion not known to yield correlation-secure TDFs.","Title: A Primitive for Proving the Security of Every Bit and About Universal Hash Functions & Hard Core Bits\nYear: 2001\n\nAbstract: We present a useful primitive, the hidden number problem, which can be exploited to prove that every bit is a hard core of specific cryptographic functions. Applications are RSA, ElGamal, Rabin and others. We give an efficient construction of a hard core predicate of any one-way function providing an alternative to the famous Goldreich-Levin Bit [3]. Furthermore, a conjectured connection between universal hash functions and hard core predicates is disproven.","Title: The Twin Diffie–Hellman Problem and Applications\nYear: 2009\n\nAbstract: We propose a new computational problem called the twin Diffie–Hellman problem. This problem is closely related to the usual (computational) Diffie–Hellman problem and can be used in many of the same cryptographic constructions that are based on the Diffie–Hellman problem. Moreover, the twin Diffie–Hellman problem is at least as hard as the ordinary Diffie–Hellman problem. However, we are able to show that the twin Diffie–Hellman problem remains hard, even in the presence of a decision oracle that recognizes solutions to the problem—this is a feature not enjoyed by the Diffie–Hellman problem, in general. Specifically, we show how to build a certain “trapdoor test” that allows us to effectively answer decision oracle queries for the twin Diffie–Hellman problem without knowing any of the corresponding discrete logarithms. Our new techniques have many applications. As one such application, we present a new variant of ElGamal encryption with very short ciphertexts, and with a very simple and tight security proof, in the random oracle model, under the assumption that the ordinary Diffie–Hellman problem is hard. We present several other applications as well, including a new variant of Diffie and Hellman’s non-interactive key exchange protocol; a new variant of Cramer–Shoup encryption, with a very simple proof in the standard model; a new variant of Boneh–Franklin identity-based encryption, with very short ciphertexts; a more robust version of a password-authenticated key exchange protocol of Abdalla and Pointcheval.","Title: Efficient hybrid encryption from ID-based encryption\nYear: 2007\n\nAbstract: This paper deals with generic transformations from ID-based key encapsulation mechanisms (IBKEM) to hybrid public-key encryption (PKE). The best generic transformation known until now is by Boneh and Katz and requires roughly 704-bit overhead in the ciphertext. We present new generic transformations that are applicable to partitioned IBKEMs. A partitioned IBKEM is an IBKEM that provides some extra structure. Such IBKEMs are quite natural and in fact nearly all known IBKEMs have this additional property. Our first transformation yields chosen-ciphertext secure PKE schemes from selective-ID secure partitioned IBKEMs with a 256-bit overhead in ciphertext size plus one extra exponentiation in encryption/decryption. As the central tool a Chameleon Hash function is used to map the identities. We also propose other methods to remove the use of Chameleon Hash, which may be of independent technical interest. Applying our transformations to existing IBKEMs we propose a number of novel PKE schemes with different trade-offs. In some concrete instantiations the Chameleon Hash can be made \"implicit\" which results in improved efficiency by eliminating the additional exponentiation. Since our transformations preserve the public verifiability property of the IBE schemes it is possible to extend our results to build threshold hybrid PKE schemes. We show an analogue generic transformation in the threshold setting and present a concrete scheme which results in the most efficient threshold PKE scheme in the standard model.","Title: Compact CCA-Secure Encryption for Messages of Arbitrary Length\nYear: 2009\n\nAbstract: This paper proposes a chosen-ciphertext secure variant of the ElGamal public-key encryption scheme which generates very compact ciphertexts for messages of arbitrary length . The ciphertext overhead (i.e., the difference between ciphertext and plaintext) is one group element only. Such a property is particularly useful when encrypting short messages such as a PIN or a credit card number in bandwidth-critical environments. On top of the compact overhead, the computational cost for encryption and decryption are almost the same as plain ElGamal encryption. The security is proven based on the strong Diffie-Hellman assumption in the random oracle model.","Title: Polynomial interpolation of cryptographic functions related to Diffie-Hellman and discrete logarithm problem\nYear: 2006\n\nAbstract: Recently, the first author introduced some cryptographic functions closely related to the Diffie-Hellman problem called P- Diffie-Hellman functions. We show that the existence of a low-degree polynomial representing a P-Diffie-Hellman function on a large set would lead to an efficient algorithm for solving the Diffie-Hellman problem. Motivated by this result we prove lower bounds on the degree of such interpolation polynomials. Analogously, we introduce a class of functions related to the discrete logarithm and show similar reduction and interpolation results.","Title: Chosen-Ciphertext security from tag-based encryption\nYear: 2006\n\nAbstract: One of the celebrated applications of Identity-Based Encryption (IBE) is the Canetti, Halevi, and Katz (CHK) transformation from any (selective-identity secure) IBE scheme into a full chosen-ciphertext secure encryption scheme. Since such IBE schemes in the standard model are known from previous work this immediately provides new chosenciphertext secure encryption schemes in the standard model. This paper revisits the notion of Tag-Based Encryption (TBE) and provides security definitions for the selective-tag case. Even though TBE schemes belong to a more general class of cryptographic schemes than IBE, we observe that (selective-tag secure) TBE is a su.cient primitive for the CHK transformation and therefore implies chosen-ciphertext secure encryption. We construct efficient and practical TBE schemes and give tight security reductions in the standard model from the Decisional Linear Assumption in gap-groups. In contrast to all known IBE schemes our TBE construction does not directly deploy pairings. Instantiating the CHK transformation with our TBE scheme results in an encryption scheme whose decryption can be carried out in one single multi-exponentiation. Furthermore, we show how to apply the techniques gained from the TBE construction to directly design a new Key Encapsulation Mechanism. Since in this case we can avoid the CHK transformation the scheme results in improved efficiency.","Title: On the Security of Padding-Based Encryption Schemes --- or --- Why We Cannot Prove OAEP Secure in the Standard Model\nYear: 2009\n\nAbstract: We investigate the security of \"padding-based\" encryption schemes in the standard model. This class contains all public-key encryption schemes where the encryption algorithm first applies some invertible public transformation to the message (the \"padding\"), followed by a trapdoor permutation. In particular, this class contains OAEP and its variants. Our main result is a black-box impossibility result showing that one cannot prove any such padding-based scheme chosen-ciphertext secure even assuming the existence of ideal trapdoor permutations. The latter is a strong ideal abstraction of trapdoor permutations which inherits all security properties of uniform random permutations.","Title: Chosen Ciphertext Security with Optimal Ciphertext Overhead\nYear: 2008\n\nAbstract: Every public-key encryption scheme has to incorporate a certain amount of randomness into its ciphertexts to provide semantic security against chosen ciphertext attacks (IND-CCA). The difference between the length of a ciphertext and the embedded message is called the ciphertext overhead . While a generic brute-force adversary running in 2 t steps gives a theoretical lower bound of t bits on the ciphertext overhead for IND-CPA security, the best known IND-CCA secure schemes demand roughly 2t bits even in the random oracle model. Is the t -bit gap essential for achieving IND-CCA security? We close the gap by proposing an IND-CCA secure scheme whose ciphertext overhead matches the generic lower bound up to a small constant. Our scheme uses a variation of a four-round Feistel network in the random oracle model and hence belongs to the family of OAEP-based schemes. Maybe of independent interest is a new efficient method to encrypt long messages exceeding the length of the permutation while retaining the minimal overhead.","Title: Identity-Based (lossy) trapdoor functions and applications\nYear: 2012\n\nAbstract: We provide the first constructions of identity-based (injective) trapdoor functions. Furthermore, they are lossy. Constructions are given both with pairings (DLIN) and lattices (LWE). Our lossy identitybased trapdoor functions provide an automatic way to realize, in the identity-based setting, many functionalities previously known only in the public-key setting. In particular we obtain the first deterministic and efficiently searchable IBE schemes and the first hedged IBE schemes, which achieve best possible security in the face of bad randomness. Underlying our constructs is a new definition, namely partial lossiness, that may be of broader interest.","Title: Searchable Encryption Revisited: Consistency Properties, Relation to Anonymous IBE, and Extensions\nYear: 2005\n\nAbstract: We identify and fill some gaps with regard to consistency (the extent to which false positives are produced) for public-key encryption with keyword search (PEKS). We define computational and statistical relaxations of the existing notion of perfect consistency, show that the scheme of Boneh et al. (Advances in Cryptology—EUROCRYPT 2004, ed. by C. Cachin, J. Camenisch, pp. 506–522, 2004) is computationally consistent, and provide a new scheme that is statistically consistent. We also provide a transform of an anonymous identity-based encryption (IBE) scheme to a secure PEKS scheme that, unlike the previous one, guarantees consistency. Finally, we suggest three extensions of the basic notions considered here, namely anonymous hierarchical identity-based encryption, public-key encryption with temporary keyword search, and identity-based encryption with keyword search.","Title: Digital Signatures with Minimal Overhead from Indifferentiable Random Invertible Functions.\nYear: 2013\n\nAbstract: In a digital signature scheme with message recovery, rather than transmitting the message m and its signature sigma, a single enhanced signature tau is transmitted. The verifier is able to recover m from tau and at the same time verify its authenticity. The two most important parameters of such a scheme are its security and overhead vertical bar tau vertical bar - vertical bar m vertical bar. A simple argument shows that for any scheme with \"n bits security\" vertical bar tau vertical bar - vertical bar m vertical bar >= n, i.e., the overhead is lower bounded by the security parameter n. Currently, the best known constructions in the random oracle model are far from this lower bound requiring an overhead of n + logq(h), where q(h) is the number of queries to the random oracle. In this paper we give a construction which basically matches the n bit lower bound. We propose a simple digital signature scheme with n + o(log q(h)) bits overhead, where q(h) denotes the number of random oracle queries. Our construction works in two steps. First, we propose a signature scheme with message recovery having optimal overhead in a new ideal model, the random invertible function model. Second, we show that a four-round Feistel network with random oracles as round functions is tightly \"public-indifferentiable\" from a random invertible function. At the core of our indifferentiability proof is an almost tight upper bound for the expected number of edges of the densest \"small\" subgraph of a random Cayley graph, which may be of independent interest.","Title: CCA2 secure IBE: standard model efficiency through authenticated symmetric encryption\nYear: 2008\n\nAbstract: We propose two constructions of chosen-ciphertext secure identity-based encryption (IBE) schemes. Our schemes have a security proof in the standard model, yet they offer performance competitive with all known random-oracle based schemes. The efficiency improvement is obtained by combining modifications of the IBE schemes by Waters [38] and Gentry [21] with authenticated symmetric encryption.","Title: Public-key encryption with non-interactive opening\nYear: 2008\n\nAbstract: We formally define the primitive of public-key encryption with non-interactive opening (PKENO), where the receiver of a cipher-text C can, convincingly and without interaction, reveal what the result was of decrypting C, without compromising the scheme's security. This has numerous applications in cryptographic protocol design, e.g., when the receiver wants to demonstrate that some information he was sent privately was not correctly formed. We give a definition based on the UC framework as well as an equivalent game-based definition. The PKENO concept was informally introduced by Damgård and Thorbek who suggested that it could be implemented based on Identity-Based Encryption. In this paper, we give direct and optimized implementations, that work without having to keep state information, unlike what one obtains from directly using IBE.","Title: Short signatures from weaker assumptions\nYear: 2011\n\nAbstract: We provide constructions of (m,1)-programmable hash functions (PHFs) for m≥2. Mimicking certain programmability properties of random oracles, PHFs can, e.g., be plugged into the generic constructions by Hofheinz and Kiltz (J. Cryptol. 2011) to yield digital signature schemes from the strong RSA and strong q-Diffie-Hellman assumptions. As another application of PHFs, we propose new and efficient constructions of digital signature schemes from weaker assumptions, i.e., from the (standard, non-strong) RSA and the (standard, non-strong) q-Diffie-Hellman assumptions. The resulting signature schemes offer interesting tradeoffs between efficiency/signature length and the size of the public-keys. For example, our q-Diffie-Hellman signatures can be as short as 200 bits; the signing algorithm of our Strong RSA signature scheme can be as efficient as the one in RSA full domain hash; compared to previous constructions, our RSA signatures are shorter (by a factor of roughly 2) and we obtain a considerable efficiency improvement (by an even larger factor). All our constructions are in the standard model, i.e., without random oracles.","Title: Optimal security proofs for full domain hash, revisited\nYear: 2012\n\nAbstract: RSA Full Domain Hash (RSA-FDH) is a digital signature scheme, secure again chosen message attacks in the random oracle model. The best known security reduction from the RSA assumption is nontight, i.e., it loses a factor of qs, where qs is the number of signature queries made by the adversary. It was furthermore proved by Coron (EUROCRYPT 2002) that a security loss of qs is optimal and cannot possibly be improved. In this work we uncover a subtle flaw in Coron's impossibility result. Concretely, we show that it only holds if the underlying trapdoor permutation is certified. Since it is well known that the RSA trapdoor permutation is (for all practical parameters) not certified, this renders Coron's impossibility result moot for RSA-FDH. Motivated by this, we revisit the question whether there is a tight security proof for RSA-FDH. Concretely, we give a new tight security reduction from a stronger assumption, the Phi-Hiding assumption introduced by Cachin et al (EUROCRYPT 1999). This justifies the choice of smaller parameters in RSA-FDH, as it is commonly used in practice. All of our results (positive and negative) extend to the probabilistic signature scheme PSS.","Title: On the Representation of Boolean Predicates of the Diffie-Hellman Function\nYear: 2003\n\nAbstract: In this work we give a non-trivial upper bound on the spectral norm of various Boolean predicates of the Diffie-Hellman function. For instance, we consider every individual bit and arbitrary unbiased intervals. Combining the bound with recent results from complexity theory we can rule out the possibility that such a Boolean function can be represented by simple functions like depth-2 threshold circuits with a small number of gates.","Title: Bonsai Trees, or How to Delegate a Lattice Basis\nYear: 2010\n\nAbstract: We introduce a new lattice-based cryptographic structure called a bonsai tree, and use it to resolve some important open problems in the area. Applications of bonsai trees include an efficient, stateless `hash-and-sign' signature scheme in the standard model (i.e., no random oracles), and the first hierarchical identity-based encryption (HIBE) scheme (also in the standard model) that does not rely on bilinear pairings. Interestingly, the abstract properties of bonsai trees seem to have no known realization in conventional number-theoretic cryptography.","Title: The Group of Signed Quadratic Residues and Applications\nYear: 2009\n\nAbstract: We consider the cryptographic group of Signed Quadratic Residues. This group is particularly useful for cryptography since it is a \"gap-group,\" in which the computational problem (i.e., computing square roots) is as hard as factoring, while the corresponding decisional problem (i.e., recognizing signed quadratic residues) is easy. We are able to show that under the factoring assumption, the Strong Diffie-Hellman assumption over the signed quadratic residues holds. That is, in this group the Diffie-Hellman problem is hard, even in the presence of a Decisional Diffie-Hellman oracle.We demonstrate the usefulness of our results by applying them to the Hybrid ElGamal encryption scheme (aka Diffie-Hellman integrated encryption scheme - DHIES). Concretely, we consider the security of the scheme when instantiated over the group of signed quadratic residues. It is known that, in the random oracle model, the scheme is chosenciphertext (CCA) secure under the Strong Diffie-Hellman assumption and hence, by our results, under the standard factoring assumption. We show that furthermore, in the standard model, Hybrid ElGamal is CCA secure under the higher residuosity assumption, given that the used hash function is four-wise independent. The latter result is obtained using the recent \"randomness extraction framework\" for hash proof systems.","Title: A Tool Box of Cryptographic Functions Related to the Diffie-Hellman Function\nYear: 2001\n\nAbstract: Given a cyclic group G and a generator g, the Diffie-Hellman function (DH) maps two group elements (ga, gb) to gab. For many groups G this function is assumed to be hard to compute. We generalize this function to the P-Diffie-Hellman function (P-DH) that maps two group elements (ga, gb) to gP(a,b) for a (non-linear) polynomial P in a and b. In this paper we show that computing DH is computationally equivalent to computing P-DH. In addition we study the corresponding decision problem. In sharp contrast to the computational case the decision problems for DH and P-DH can be shown to be not generically equivalent for most polynomials P. Furthermore we show that there is no generic algorithm that computes or decides the P-DH function in polynomial time.","Title: A note on secure computation of the moore-penrose pseudoinverse and its application to secure linear algebra\nYear: 2007\n\nAbstract: This work deals with the communication complexity of secure multi-party protocols for linear algebra problems. In our model, complexity is measured in terms of the number of secure multiplications required and protocols terminate within a constant number of rounds of communication. Previous work by Cramer and Damgård proposes secure protocols for solving systems Ax = b of m linear equations in n variables over a finite field, with m ≤ n. The complexity of those protocols is n5. We show a new upper bound of m4 + n2m secure multiplications for this problem, which is clearly asymptotically smaller. Our main point, however, is that the advantage can be substantial in case m is much smaller than n. Indeed, if m = √n, for example, the complexity goes down from n5 to n2.5. Our secure protocols rely on some recent advances concerning the computation of the Moore-Penrose pseudo-inverse of matrices over fields of positive characteristic. These computations are based on the evaluation of a certain characteristic polynomial, in combination with variations on a well-known technique due to Mulmuley that helps to control the effects of non-zero characteristic. We also introduce a new method for secure polynomial evaluation that exploits properties of Chebychev polynomials, as well as a new secure protocol for computing the characteristic polynomial of a matrix based on Leverrier's lemma that exploits this new method.","Title: Efficient authentication from hard learning problems\nYear: 2011\n\nAbstract: We construct efficient authentication protocols and message-authentication codes (MACs) whose security can be reduced to the learning parity with noise (LPN) problem. Despite a large body of work - starting with the HB protocol of Hopper and Blum in 2001 - until now it was not even known how to construct an efficient authentication protocol from LPN which is secure against man-in-the-middle (MIM) attacks. A MAC implies such a (two-round) protocol.","Title: A New Randomness Extraction Paradigm for Hybrid Encryption\nYear: 2009\n\nAbstract: We present a new approach to the design of IND-CCA2 secure hybrid encryption schemes in the standard model. Our approach provides an efficient generic transformation from 1-universal to 2-universal hash proof systems. The transformation involves a randomness extractor based on a 4-wise independent hash function as the key derivation function. Our methodology can be instantiated with efficient schemes based on standard intractability assumptions such as Decisional Diffie-Hellman, Quadratic Residuosity, and Paillier's Decisional Composite Residuosity. Interestingly, our framework also allows to prove IND-CCA2 security of a hybrid version of 1991's Damgård's ElGamal public-key encryption scheme under the DDH assumption.","Title: Practical Chosen Ciphertext Secure Encryption from Factoring\nYear: 2013\n\nAbstract: We propose a practical public-key encryption scheme whose security against chosen-ciphertext attacks can be reduced in the standard model to the assumption that factoring is intractable.","Title: Chosen-ciphertext secure key-encapsulation based on gap hashed Diffie-Hellman\nYear: 2007\n\nAbstract: We propose a practical key encapsulation mechanism with a simple and intuitive design concept. Security against chosen-ciphertext attacks can be proved in the standard model under a new assumption, the Gap Hashed Diffie-Hellman (GHDH) assumption. The security reduction is tight and simple. Secure key encapsulation, combined with an appropriately secure symmetric encryption scheme, yields a hybrid public-key encryption scheme which is secure against chosen-ciphertext attacks. The implied encryption scheme is very efficient: compared to the previously most efficient scheme by Kurosawa and Desmedt [Crypto 2004] it has 128 bits shorter ciphertexts, between 25-50% shorter public/secret keys, and it is slightly more efficient in terms of encryption/decryption speed. Furthermore, our scheme enjoys (the option of) public verifiability of the ciphertexts and it inherits all practical advantages of secure hybrid encryption.","Title: Encryption schemes secure against chosen-ciphertext selective opening attacks\nYear: 2010\n\nAbstract: Imagine many small devices send data to a single receiver, encrypted using the receiver’s public key. Assume an adversary that has the power to adaptively corrupt a subset of these devices. Given the information obtained from these corruptions, do the ciphertexts from uncorrupted devices remain secure? Recent results suggest that conventional security notions for encryption schemes (like IND-CCA security) do not suffice in this setting. To fill this gap, the notion of security against selective-opening attacks (SOA security) has been introduced. It has been shown that lossy encryption implies SOA security against a passive, i.e., only eavesdropping and corrupting, adversary (SO-CPA). However, the known results on SOA security against an active adversary (SO-CCA) are rather limited. Namely, while there exist feasibility results, the (time and space) complexity of currently known SO-CCA secure schemes depends on the number of devices in the setting above. In this contribution, we devise a new solution to the selective opening problem that does not build on lossy encryption. Instead, we combine techniques from non-committing encryption and hash proof systems with a new technique (dubbed “cross-authentication codes”) to glue several ciphertext parts together. The result is a rather practical SO-CCA secure public-key encryption scheme that does not suffer from the efficiency drawbacks of known schemes. Since we build upon hash proof systems, our scheme can be instantiated using standard number-theoretic assumptions such as decisional Diffie-Hellman DDH), decisional composite residuosity (DCR), and quadratic residuosity (QR). Besides, we construct a conceptually very simple and comparatively efficient SO-CPA secure scheme from (slightly enhanced) trapdoor one-way permutations. We stress that our schemes are completely independent of the number of challenge ciphertexts, and we do not make assumptions about the underlying message distribution (beyond being efficiently samplable). In particular, we do not assume efficient conditional re-samplability of the message distribution. Hence, our schemes are secure in arbitrary settings, even if it is not known in advance how many ciphertexts might be considered for corruptions.","Title: Quasi-Adaptive NIZK for Linear Subspaces Revisited.\nYear: 2015\n\nAbstract: Non-interactive zero-knowledge (NIZK) proofs for algebraic relations in a group, such as the Groth-Sahai proofs, are an extremely powerful tool in pairing-based cryptography. A series of recent works focused on obtaining very efficient NIZK proofs for linear spaces in a weaker quasi-adaptive model. We revisit recent quasi-adaptive NIZK constructions, providing clean, simple, and improved constructions via a conceptually different approach inspired by recent developments in identity-based encryption. We then extend our techniques also to linearly homomorphic structure-preserving signatures, an object both of independent interest and with many applications.","Title: (Hierarchical) Identity-Based Encryption from Affine Message Authentication.\nYear: 2014\n\nAbstract: We provide a generic transformation from any affine message authentication code (MAC) to an identity-based encryption (IBE) scheme over pairing groups of prime order. If the MAC satisfies a security notion related to unforgeability against chosen-message attacks and, for example, the k-Linear assumption holds, then the resulting IBE scheme is adaptively secure. Our security reduction is tightness preserving, i.e., if the MAC has a tight security reduction so has the IBE scheme. Furthermore, the transformation also extends to hierarchical identity-based encryption (HIBE). We also show how to construct affine MACs with a tight security reduction to standard assumptions. This, among other things, provides the first tightly secure HIBE in the standard model.","Title: Tightly Secure CCA-Secure Encryption without Pairings.\nYear: 2016\n\nAbstract: We present the first CCA-secure public-key encryption scheme based on DDH where the security loss is independent of the number of challenge ciphertexts and the number of decryption queries. Our construction extends also to the standard k-Lin assumption in pairing-free groups, whereas all prior constructions starting with Hofheinz and Jager (Crypto ’12) rely on the use of pairings. Moreover, our construction improves upon the concrete efficiency of existing schemes, reducing the ciphertext overhead by about half (to only 3 group elements under DDH), in addition to eliminating the use of pairings. We also show how to use our techniques in the NIZK setting. Specifically, we construct the first tightly simulation-sound designated-verifier NIZK for linear languages without pairings. Using pairings, we can turn our construction into a highly optimized publicly verifiable NIZK with tight simulation-soundness.","Title: Optimal Security Proofs for Signatures from Identification Schemes.\nYear: 2016\n\nAbstract: We perform a concrete security treatment of digital signature schemes obtained from canonical identification schemes via the Fiat-Shamir transform. If the identification scheme is random self-reducible and satisfies the weakest possible security notion hardness of key-recoverability, then the signature scheme obtained via Fiat-Shamir is unforgeable against chosen-message attacks in the multi-user setting. Our security reduction is in the random oracle model and loses a factor of roughly $$Q_h$$, the number of hash queries. Previous reductions incorporated an additional multiplicative loss of N, the number of users in the system. Our analysis is done in small steps via intermediate security notions, and all our implications have relatively simple proofs. Furthermore, for each step, we show the optimality of the given reduction in terms of model assumptions and tightness. As an important application of our framework, we obtain a concrete security treatment for Schnorr signatures in the multi-user setting.","Title: Two-Round Man-in-the-Middle Security from LPN.\nYear: 2015\n\nAbstract: Secret-key authentication protocols have recently received a considerable amount of attention, and a long line of research has been devoted to devising efficient protocols with security based on the hardness of the learning-parity with noise (LPN) problem, with the goal of achieving low communication and round complexities, as well as highest possible security guarantees. In this paper, we construct 2-round authentication protocols that are secure against sequential man-in-the-middle (MIM) attacks with tight reductions to LPN, Field-LPN, or other problems. The best prior protocols had either loose reductions and required 3 rounds (Lyubashevsky and Masny, CRYPTO'13) or had a much larger key (Kiltz et al., EUROCRYPT'11 and Dodis et al., EUROCRYPT'12). Our constructions follow from a new generic deterministic and round-preserving transformation enhancing actively-secure protocols of a special form to be sequentially MIM-secure while only adding a limited amount of key material and computation.","Title: Standard Security Does Imply Security Against Selective Opening for Markov Distributions.\nYear: 2016\n\nAbstract: About three decades ago it was realized that implementing private channels between parties which can be adaptively corrupted requires an encryption scheme that is secure against selective opening attacks. Whether standard (IND-CPA) security implies security against selective opening attacks has been a major open question since. The only known reduction from selective opening to IND-CPA security loses an exponential factor. A polynomial reduction is only known for the very special case where the distribution considered in the selective opening security experiment is a product distribution, i.e., the messages are sampled independently from each other. In this paper we give a reduction whose loss is quantified via the dependence graph (where message dependencies correspond to edges) of the underlying message distribution. In particular, for some concrete distributions including Markov distributions, our reduction is polynomial.","Title: Tightly CCA-Secure Encryption Without Pairings.\nYear: 2016\n\nAbstract: We present the first CCA-secure public-key encryption scheme based on DDH where the security loss is independent of the number of challenge ciphertexts and the number of decryption queries. Our construction extends also to the standard k-$$\\\\mathsf {Lin} $$ assumption in pairing-free groups, whereas all prior constructions starting with Hofheinz and Jager Crypto '12 rely on the use of pairings. Moreover, our construction improves upon the concrete efficiency of existing schemes, reducing the ciphertext overhead by about half to only $$3$$ group elements under DDH, in addition to eliminating the use of pairings. We also show how to use our techniques in the NIZK setting. Specifically, we construct the first tightly simulation-sound designated-verifier NIZK for linear languages without pairings. Using pairings, we can turn our construction into a highly optimized publicly verifiable NIZK with tight simulation-soundness.","Title: Selective opening security of practical public-key encryption schemes.\nYear: 2016\n\nAbstract: The authors show that two well-known and widely employed public-key encryption schemes - RSA optimal asymmetric encryption padding (RSA-OAEP) and Diffie-Hellman integrated encryption scheme (DHIES), instantiated with a one-time pad, - are secure under (the strong, simulation-based security notion of) selective opening security against chosen-ciphertext attacks in the random oracle model. Both sche...","Title: On the Provable Security of (EC)DSA Signatures.\nYear: 2016\n\nAbstract: Among the signature schemes most widely deployed in practice are the DSA (Digital Signature Algorithm) and its elliptic curves variant ECDSA. They are represented in many international standards, including IEEE P1363, ANSI X9.62, and FIPS 186-4. Their popularity stands in stark contrast to the absence of rigorous security analyses: Previous works either study modified versions of (EC)DSA or provide a security analysis of unmodified ECDSA in the generic group model. Unfortunately, works following the latter approach assume abstractions of non-algebraic functions over generic groups for which it remains unclear how they translate to the security of ECDSA in practice. For instance, it has been pointed out that prior results in the generic group model actually establish strong unforgeability of ECDSA, a property that the scheme de facto does not possess. As, further, no formal results are known for DSA, understanding the security of both schemes remains an open problem. In this work we propose GenericDSA, a signature framework that subsumes both DSA and ECDSA in unmodified form. It carefully models the \\\"modulo q\\\" conversion function of (EC)DSA as a composition of three independent functions. The two outer functions mimic algebraic properties in the function's domain and range, the inner one is modeled as a bijective random oracle. We rigorously prove results on the security of GenericDSA that indicate that forging signatures in (EC)DSA is as hard as solving discrete logarithms. Importantly, our proofs do not assume generic group behavior.","Title: A Modular Analysis of the Fujisaki-Okamoto Transformation.\nYear: 2017\n\nAbstract: The Fujisaki-Okamoto (FO) transformation (CRYPTO 1999 and Journal of Cryptology 2013) turns any weakly secure public-key encryption scheme into a strongly (i.e., (mathsf {IND}text {-}mathsf {CCA})) secure one in the random oracle model. Unfortunately, the FO analysis suffers from several drawbacks, such as a non-tight security reduction, and the need for a perfectly correct scheme. While several alternatives to the FO transformation have been proposed, they have stronger requirements, or do not obtain all desired properties.","Title: CRYSTALS - Kyber: A CCA-Secure Module-Lattice-Based KEM\nYear: 2018\n\nAbstract: Rapid advances in quantum computing, together with the announcement by the National Institute of Standards and Technology (NIST) to define new standards for digitalsignature, encryption, and key-establishment protocols, have created significant interest in post-quantum cryptographic schemes. This paper introduces Kyber (part of CRYSTALS - Cryptographic Suite for Algebraic Lattices - a package submitted to NIST post-quantum standardization effort in November 2017), a portfolio of post-quantum cryptographic primitives built around a key-encapsulation mechanism (KEM), based on hardness assumptions over module lattices. Our KEM is most naturally seen as a successor to the NEWHOPE KEM (Usenix 2016). In particular, the key and ciphertext sizes of our new construction are about half the size, the KEM offers CCA instead of only passive security, the security is based on a more general (and flexible) lattice problem, and our optimized implementation results in essentially the same running time as the aforementioned scheme. We first introduce a CPA-secure public-key encryption scheme, apply a variant of the Fujisaki-Okamoto transform to create a CCA-secure KEM, and eventually construct, in a black-box manner, CCA-secure encryption, key exchange, and authenticated-key-exchange schemes. The security of our primitives is based on the hardness of Module-LWE in the classical and quantum random oracle models, and our concrete parameters conservatively target more than 128 bits of postquantum security.","Title: Tightly-Secure Signatures from Five-Move Identification Protocols.\nYear: 2017\n\nAbstract: We carry out a concrete security analysis of signature schemes obtained from five-move identification protocols via the Fiat-Shamir transform. Concretely, we obtain tightly-secure signatures based on the computational Diffie-Hellman (CDH), the short-exponent CDH, and the Factoring (FAC) assumptions. All our signature schemes have tight reductions to search problems, which is in stark contrast to all known signature schemes obtained from the classical Fiat-Shamir transform (based on three-move identification protocols), which either have a non-tight reduction to a search problem, or a tight reduction to a (potentially) stronger decisional problem. Surprisingly, our CDH-based scheme turns out to be (a slight simplification of) the Chevallier-Mames signature scheme (CRYPTO 05), thereby providing a theoretical explanation of its tight security proof via five-move identification protocols.","Title: On the One-Per-Message Unforgeability of (EC)DSA and Its Variants.\nYear: 2017\n\nAbstract: The American signature standards DSA and ECDSA, as well as their Russian and Chinese counterparts GOST 34.10 and SM2, are of utmost importance in the current security landscape. The mentioned schemes are all rooted in the Elgamal signature scheme (1984) and use a hash function and a cyclic group as building blocks. Unfortunately, authoritative security guarantees for the schemes are still due: All existing positive results on their security use aggressive idealization approaches, like the generic group model, leading to debatable overall results.","Title: CRYSTALS-Dilithium: A Lattice-Based Digital Signature Scheme.\nYear: 2018\n\nAbstract: In this paper, we present the lattice-based signature scheme Dilithium, which is a component of the CRYSTALS (Cryptographic Suite for Algebraic Lattices) suite that was submitted to NIST’s call for post-quantum cryptographic standards. The design of the scheme avoids all uses of discrete Gaussian sampling and is easily implementable in constant-time. For the same security levels, our scheme has a public key that is 2.5X smaller than the previously most efficient lattice-based schemes that did not use Gaussians, while having essentially the same signature size. In addition to the new design, we significantly improve the running time of the main component of many lattice-based constructions – the number theoretic transform. Our AVX2-based implementation results in a speed-up of roughly a factor of 2 over the previously best algorithms that appear in the literature. The techniques for obtaining this speed-up also have applications to other lattice-based schemes.","Title: An Algebraic Framework for Diffie–Hellman Assumptions\nYear: 2013\n\nAbstract: We put forward a new algebraic framework to generalize and analyze Diffie---Hellman like decisional assumptions which allows us to argue about security and applications by considering only algebraic properties. Our $$\\\\mathcal {D}_{\\\\ell ,k}\\\\text{- }\\\\textsf {MDDH}$$Dℓ,k-MDDH Assumption states that it is hard to decide whether a vector in $$\\\\mathbb {G}^\\\\ell $$Gℓ is linearly dependent of the columns of some matrix in $$\\\\mathbb {G}^{\\\\ell \\\\times k}$$Gℓ×k sampled according to distribution $$\\\\mathcal {D}_{\\\\ell ,k}$$Dℓ,k. It covers known assumptions such as $$\\\\textsf {DDH},\\\\, 2\\\\text{- }\\\\textsf {Lin}$$DDH,2-Lin (Linear Assumption) and $$k\\\\text{- }\\\\textsf {Lin}$$k-Lin (the k-Linear Assumption). Using our algebraic viewpoint, we can relate the generic hardness of our assumptions in m-linear groups to the irreducibility of certain polynomials which describe the output of $$\\\\mathcal {D}_{\\\\ell ,k}$$Dℓ,k. We use the hardness results to find new distributions for which the $$\\\\mathcal {D}_{\\\\ell ,k}\\\\text{- }\\\\textsf {MDDH}$$Dℓ,k-MDDH Assumption holds generically in m-linear groups. In particular, our new assumptions $$2\\\\text{- }\\\\textsf {SCasc}$$2-SCasc and $$2\\\\text{- }\\\\textsf {ILin}$$2-ILin are generically hard in bilinear groups and, compared to $$2\\\\text{- }\\\\textsf {Lin}$$2-Lin, have shorter description size, which is a relevant parameter for efficiency in many applications. These results support using our new assumptions as natural replacements for the $$2\\\\text{- }\\\\textsf {Lin}$$2-Lin assumption which was already used in a large number of applications. To illustrate the conceptual advantages of our algebraic framework, we construct several fundamental primitives based on any $$\\\\textsf {MDDH}$$MDDH Assumption. In particular, we can give many instantiations of a primitive in a compact way, including public-key encryption, hash proof systems, pseudo-random functions, and Groth---Sahai NIZK and NIWI proofs. As an independent contribution, we give more efficient NIZK and NIWI proofs for membership in a subgroup of $$\\\\mathbb {G}^\\\\ell $$Gℓ. The results imply very significant efficiency improvements for a large number of schemes.","Title: The Algebraic Group Model and its Applications.\nYear: 2018\n\nAbstract: One of the most important and successful tools for assessing hardness assumptions in cryptography is the Generic Group Model (GGM). Over the past two decades, numerous assumptions and protocols have been analyzed within this model. While a proof in the GGM can certainly provide some measure of confidence in an assumption, its scope is rather limited since it does not capture group-specific algorithms that make use of the representation of the group. To overcome this limitation, we propose the Algebraic Group Model (AGM), a model that lies in between the Standard Model and the GGM. It is the first restricted model of computation covering group-specific algorithms yet allowing to derive simple and meaningful security statements. To prove its usefulness, we show that several important assumptions, among them the Computational Diffie-Hellman, the Strong Diffie-Hellman, and the interactive LRSW assumptions, are equivalent to the Discrete Logarithm (DLog) assumption in the AGM. On the more practical side, we prove tight security reductions for two important schemes in the AGM to DLog or a variant thereof: the BLS signature scheme and Groth's zero-knowledge SNARK (EUROCRYPT 2016), which is the most efficient SNARK for which only a proof in the GGM was known. Our proofs are quite simple and therefore less prone to subtle errors than those in the GGM. Moreover, in combination with known lower bounds on the Discrete Logarithm assumption in the GGM, our results can be used to derive lower bounds for all the above-mentioned results in the GGM.","Title: Generic Authenticated Key Exchange in the Quantum Random Oracle Model.\nYear: 2018\n\nAbstract: We propose \\\\(\\\\mathsf {FO_\\\\mathsf {AKE}}\\\\), a generic construction of two-message authenticated key exchange (AKE) from any passively secure public key encryption (PKE) in the quantum random oracle model (QROM). Whereas previous AKE constructions relied on a Diffie-Hellman key exchange or required the underlying PKE scheme to be perfectly correct, our transformation allows arbitrary PKE schemes with non-perfect correctness. Dealing with imperfect schemes is one of the major difficulties in a setting involving active attacks. Our direct construction, when applied to schemes such as the submissions to the recent NIST post-quantum competition, is more natural than previous AKE transformations. Furthermore, we avoid the use of (quantum-secure) digital signature schemes which are considerably less efficient than their PKE counterparts. As a consequence, we can instantiate our AKE transformation with any of the submissions to the recent NIST competition, e.g., ones based on codes and lattices.","Title: Lossy Trapdoor Permutations with Improved Lossiness.\nYear: 2019\n\nAbstract: Lossy trapdoor functions (Peikert and Waters, STOC 2008 and SIAM J. Computing 2011) imply, via black-box transformations, a number of interesting cryptographic primitives, including chosen-ciphertext secure public-key encryption. Kiltz, O’Neill, and Smith (CRYPTO 2010) showed that the RSA trapdoor permutation is lossy under the Phi-hiding assumption, but syntactically it is not a lossy trapdoor function since it acts on (mathbb {Z}_N) and not on strings. Using a domain extension technique by Freeman et al. (PKC 2010 and J. Cryptology 2013) it can be extended to a lossy trapdoor permutation, but with considerably reduced lossiness.","Title: Tightly-Secure Authenticated Key Exchange.\nYear: 2014\n\nAbstract: We construct the first Authenticated Key Exchange (AKE) protocol whose security does not degrade with an increasing number of users or sessions. We describe a three-message protocol and prove security in an enhanced version of the classical Bellare-Rogaway security model. Our construction ismodular, it can be instantiated efficiently from standard assumptions (such as the SXDH or DLIN assumptions in pairing-friendly groups). For instance, we provide an SXDH-based protocol with only 14 group elements and 4 exponents communication complexity (plus some bookkeeping information). Along the way we develop new, stronger security definitions for digital signatures and key encapsulation mechanisms. For instance, we introduce a security model for digital signatures that provides existential unforgeability under chosen-message attacks in a multi-user setting with adaptive corruptions of secret keys. We show how to construct efficient schemes that satisfy the new definitions with tight security proofs under standard assumptions.","Title: A Modular Treatment of Blind Signatures from Identification Schemes.\nYear: 2019\n\nAbstract: We propose a modular security treatment of blind signatures derived from linear identification schemes in the random oracle model. To this end, we present a general framework that captures several well known schemes from the literature and allows to prove their security. Our modular security reduction introduces a new security notion for identification schemes called One-More-Man In the Middle Security which we show equivalent to the classical One-More-Unforgeability notion for blind signatures. We also propose a generalized version of the Forking Lemma due to Bellare and Neven (CCS 2006) and show how it can be used to greatly improve the understandability of the classical security proofs for blind signatures schemes by Pointcheval and Stern (Journal of Cryptology 2000).","Title: On the Security of Two-Round Multi-Signatures\nYear: 2019\n\nAbstract: A multi-signature scheme allows a group of signers to collaboratively sign a message, creating a single signature that convinces a verifier that every individual signer approved the message. The increased interest in technologies to decentralize trust has triggered the proposal of highly efficient two-round Schnorr-based multi-signature schemes designed to scale up to thousands of signers, namely BCJ by Bagherzandi et al. (CCS 2008), MWLD by Ma et al. (DCC 2010), CoSi by Syta et al. (S&P 2016), and MuSig by Maxwell et al. (ePrint 2018). In this work, we point out serious security issues in all currently known two-round multi-signature schemes (without pairings). First, we prove that none of the schemes can be proved secure without radically departing from currently known techniques. Namely, we show that if the one-more discrete-logarithm problem is hard, then no algebraic reduction exists that proves any of these schemes secure under the discrete-logarithm or one-more discrete-logarithm problem. We point out subtle flaws in the published security proofs of the above schemes (except CoSi, which was not proved secure) to clarify the contradiction between our result and the existing proofs. Next, we describe practical sub-exponential attacks on all schemes, providing further evidence to their insecurity. Being left without two-round multi-signature schemes, we present mBCJ, a variant of the BCJ scheme that we prove secure under the discrete-logarithm assumption in the random-oracle model. Our experiments show that mBCJ barely affects scalability compared to CoSi, allowing 16384 signers to collaboratively sign a message in about 2 seconds, making it a highly practical and provably secure alternative for large-scale deployments.","Title: On the Impossibility of Purely Algebraic Signatures\nYear: 2021\n\nAbstract: The existence of one-way functions implies secure digital signatures, but not public-key encryption (at least in a black-box setting). Somewhat surprisingly, though, efficient public-key encryption schemes appear to be much easier to construct from concrete algebraic assumptions (such as the factoring of Diffie-Hellman-like assumptions) than efficient digital signature schemes. In this work, we provide one reason for this apparent difficulty to construct efficient signature schemes. Specifically, we prove that a wide range of algebraic signature schemes (in which verification essentially checks a number of linear equations over a group) fall to conceptually surprisingly simple linear algebra attacks. In fact, we prove that in an algebraic signature scheme, sufficiently many signatures can be linearly combined to a signature of a fresh message. We present attacks both in known-order and hidden-order groups (although in hidden-order settings, we have to restrict our definition of algebraic signatures a little). More explicitly, we show: - the insecurity of all algebraic signature schemes in Maurer's generic group model (in pairing-free groups), as long as these schemes do not rely on other cryptographic assumptions, such as hash functions. - the insecurity of a natural class of signatures in hidden-order groups, where verification consists of linear equations over group elements. We believe that this highlights the crucial role of public verifiability in digital signature schemes. Namely, while public-key encryption schemes do not require any publicly verifiable structure on ciphertexts, it is exactly this structure on signatures that invites attacks like ours and makes it hard to construct efficient signatures.","Title: Faster Lattice-Based KEMs via a Generic Fujisaki-Okamoto Transform Using Prefix Hashing\nYear: 2021\n\nAbstract: ABSTRACTConstructing an efficient CCA-secure KEM is generally done by first constructing a passively-secure PKE scheme, and then applying the Fujisaki-Okamoto (FO) transformation. The original FO transformation was designed to offer security in a single user setting. A stronger notion, known as multi-user security, considers the attacker's advantage in breaking one of many user's ciphertexts. Bellare et al. (EUROCRYPT 2000) showed that standard single user security implies multi-user security with a multiplicative tightness gap equivalent to the number of users. To obtain even more confidence in the security of KEMs in the multi-user setting, it is a common design paradigm to also \"domain separate'' the random oracles of each user by including his public key as an input to the hash function. We are not aware of any formal analysis of this technique, but it was at least informally thought to be a computationally cheap way to add security. This design principle was carried over into the FO transformations used by several schemes in the NIST post-quantum standardization effort -- notably the lattice-based schemes Kyber and Saber, which are two of the four KEM finalists. In this work, we formally analyze domain separation in the context of the FO transformation in the multi-user setting. We first show that including the public key in the hash function is indeed important for the tightness of the security reductions in the ROM and the QROM. At the same time, we show that including the entire public key into the hash function is unnecessarily wasteful -- it is enough to include just a small (e.g. $32$ byte) unpredictable part of the key to achieve the same security. Reducing the input of the hash function results in a very noticeable improvement in the running time of the lattice-based KEMs. In particular, using this generic transform results in a 2X - 3X speed-up over the current (Round 3) key generation and encapsulation procedures in Kyber, and up to a 40% improvement in the same functions in Saber.","Title: Authenticated Key Exchange And Signatures With Tight Security In The Standard Model\nYear: 2021\n\nAbstract: We construct the first authenticated key exchange protocols that achieve tight security in the standard model. Previous works either relied on techniques that seem to inherently require a random oracle, or achieved only \"Multi-Bit-Guess\" security, which is not known to compose tightly, for instance, to build a secure channel.Our constructions are generic, based on digital signatures and key encapsulation mechanisms (KEMs). The main technical challenges we resolve is to determine suitable KEM security notions which on the one hand are strong enough to yield tight security, but at the same time weak enough to be efficiently instantiable in the standard model, based on standard techniques such as universal hash proof systems.Digital signature schemes with tight multi-user security in presence of adaptive corruptions are a central building block, which is used in all known constructions of tightly-secure AKE with full forward security. We identify a subtle gap in the security proof of the only previously known efficient standard model scheme by Bader et al. (TCC 2015). We develop a new variant, which yields the currently most efficient signature scheme that achieves this strong security notion without random oracles and based on standard hardness assumptions.","Title: Chosen Ciphertext Security With Optimal Ciphertext Overhead\nYear: 2010\n\nAbstract: Every public-key encryption scheme has to incorporate a certain amount of randomness into its ciphertexts to provide semantic security against chosen ciphertext attacks (IND-CCA). The difference between the length of a ciphertext and the embedded message is called the ciphertext overhead. While a generic brute-force adversary running in 2(t) steps gives a theoretical lower bound of t bits on the ciphertext overhead for IND-CPA security, the best known IND-CCA secure schemes demand roughly 2t bits even in the random oracle model. Is the t-bit gap essential for achieving IND-CCA security? We close the gap by proposing an IND-CCA secure scheme whose ciphertext overhead matches the generic lower bound up to a small constant. Our scheme uses a variation of a four-round Feistel network in the random oracle model and hence belongs to the family of OAEP-based schemes. Maybe of independent interest is a new efficient method to encrypt long messages exceeding the length of the permutation while retaining the minimal overhead."],"string":"[\n \"Title: Certifying RSA\\nYear: 2012\\n\\nAbstract: We propose an algorithm that, given an arbitrary N of unknown factorization and prime e ≥ N1/4+ε, certifies whether the RSA function RSAN,e(x) :=xe mod N defines a permutation over ℤ*N or not. The algorithm uses Coppersmith's method to find small solutions of polynomial equations and runs in time O(ε−8 log2N). Previous certification techniques required eN.\",\n \"Title: Message authentication, revisited\\nYear: 2012\\n\\nAbstract: Traditionally, symmetric-key message authentication codes (MACs) are easily built from pseudorandom functions (PRFs). In this work we propose a wide variety of other approaches to building efficient MACs, without going through a PRF first. In particular, unlike deterministic PRF-based MACs, where each message has a unique valid tag, we give a number of probabilistic MAC constructions from various other primitives/assumptions. Our main results are summarized as follows: — We show several new probabilistic MAC constructions from a variety of general assumptions, including CCA-secure encryption, Hash Proof Systems and key-homomorphic weak PRFs. By instantiating these frameworks under concrete number theoretic assumptions, we get several schemes which are more efficient than just using a state-of-the-art PRF instantiation under the corresponding assumption. — For probabilistic MACs, unlike deterministic ones, unforgeability against a chosen message attack (uf-cma ) alone does not imply security if the adversary can additionally make verification queries (uf-cmva ). We give an efficient generic transformation from any uf-cma secure MAC which is \\\"message-hiding\\\" into a uf-cmva secure MAC. This resolves the main open problem of Kiltz et al. from Eurocrypt'11; By using our transformation on their constructions, we get the first efficient MACs from the LPN assumption. — While all our new MAC constructions immediately give efficient actively secure, two-round symmetric-key identification schemes, we also show a very simple, three-round actively secure identification protocol from any weak PRF. In particular, the resulting protocol is much more efficient than the trivial approach of building a regular PRF from a weak PRF.\",\n \"Title: Complexity theoretic aspects of some cryptographic functions\\nYear: 2003\\n\\nAbstract: In this work, we are interested in non-trivial upper bounds on the spectral norm of binary matrices M from {-1, 1}N × N. It is known that the distributed Boolean function represented by M is hard to compute in various restricted models of computation if the spectral norm is bounded from above by N1-Ɛ, where Ɛ 0 denotes a fixed constant. For instance, the size of a two-layer threshold circuit (with polynomially bounded weights for the gates in the hidden layer, but unbounded weights for the output gate) grows exponentially fast with n:= logN. We prove sufficient conditions on M that imply small spectral norms (and thus high computational complexity in restricted models). Our general results cover specific cases, where the matrix M represents a bit (the least significant bit or other fixed bits) of a cryptographic decoding function. For instance, the decoding functions of the Pointcheval [9], the El Gamal [6], and the RSA-Paillier [2] cryptosystems can be addressed by our technique. In order to obtain our results, we make a detour on exponential sums and on spectral norms of matrices with complex entries. This method might be considered interesting in its own right.\",\n \"Title: On the limitations of the spread of an IBE-to-PKE transformation\\nYear: 2006\\n\\nAbstract: By a generic transformation by Canetti, Halevi, and Katz (CHK) every Identity-based encryption (IBE) scheme implies a chosen-ciphertext secure public-key encryption (PKE) scheme. In the same work it is claimed that this transformation maps the two existing IBE schemes to two new and different chosen-ciphertext secure encryption schemes, each with individual advantages over the other. In this work we reconsider one of the two specific instantiations of the CHK transformation (when applied to the “second Boneh/Boyen IBE scheme”). We demonstrate that by applying further simplifications the resulting scheme can be proven secure under a weaker assumption than the underlying IBE scheme. Surprisingly, our simplified scheme nearly converges to a recent encryption scheme due to Boyen, Mei, and Waters which itself was obtained from the other specific instantiation of the CHK transformation (when applied to the “first Boneh/Boyen IBE scheme”). We find this particularly interesting since the two underlying IBE schemes are completely different. The bottom line of this paper is that the claim made by Canetti, Halevi, and Katz needs to be reformulated to: the CHK transformation maps the two known IBE schemes to nearly one single encryption scheme.\",\n \"Title: Cryptographic protocols from lattices\\nYear: 2010\\n\\nAbstract: In this talk, we will introduce abstract tools and techniques for working with lattices from the perspective of a cryptographic protocol designer. We will also show how to apply these tools to yield a number of provably secure public-key primitives ranging from digital signatures and public-key encryption, to more advanced protocols such as (hierarchical) identity-based encryption.\",\n \"Title: Leakage Resilient ElGamal Encryption\\nYear: 2010\\n\\nAbstract: Blinding is a popular and well-known countermeasure to protect public-key cryptosystems against side-channel attacks. The high level idea is to randomize an exponentiation in order to prevent multiple measurements of the same operation on different data, as such measurements might allow the adversary to learn the secret exponent. Several variants of blinding have been proposed in the literature, using additive or multiplicative secret-sharing to blind either the base or the exponent. These countermeasures usually aim at preventing particular side-channel attacks (mostly power analysis) and come without any formal security guarantee. In this work we investigate to which extend blinding can provide provable security against a general class of side-channel attacks. Surprisingly, it turns out that in the context of public-key encryption some blinding techniques are more suited than others. In particular, we consider a multiplicatively blinded version of ElGamal public-key encryption where we prove that the scheme, instantiated over bilinear groups of prime order p (where p 1 is not smooth) is leakage resilient in the generic-group model. Here we consider the model of chosen-ciphertext security in the presence of continuous leakage, i.e., the scheme remains chosen-ciphertext secure even if with every decryption query the adversary can learn a bounded amount (roughly log(p)/2 bits) of arbitrary, adversarially chosen information about the computation. we conjecture that the scheme, instantiated over arbitrary groups of prime order p (where p 1 is not smooth) is leakage resilient. Previous to this work no encryption scheme secure against continuous leakage was known. Constructing a scheme that can be proven, secure in the standard model remains an interesting open problem.\",\n \"Title: Lapin: an efficient authentication protocol based on Ring-LPN\\nYear: 2012\\n\\nAbstract: We propose a new authentication protocol that is provably secure based on a ring variant of the learning parity with noise (LPN) problem. The protocol follows the design principle of the LPN-based protocol from Eurocrypt'11 (Kiltz et al.), and like it, is a two round protocol secure against active attacks. Moreover, our protocol has small communication complexity and a very small footprint which makes it applicable in scenarios that involve low-cost, resource-constrained devices. Performance-wise, our protocol is more efficient than previous LPN-based schemes, such as the many variants of the Hopper-Blum (HB) protocol and the aforementioned protocol from Eurocrypt'11. Our implementation results show that it is even comparable to the standard challenge-and-response protocols based on the AES block-cipher. Our basic protocol is roughly 20 times slower than AES, but with the advantage of having 10 times smaller code size. Furthermore, if a few hundred bytes of non-volatile memory are available to allow the storage of some off-line pre-computations, then the online phase of our protocols is only twice as slow as AES.\",\n \"Title: Simple and efficient public-key encryption from computational diffie-hellman in the standard model\\nYear: 2010\\n\\nAbstract: This paper proposes practical chosen-ciphertext secure public-key encryption systems that are provably secure under the computational Diffie-Hellman assumption, in the standard model. Our schemes are conceptually simpler and more efficient than previous constructions. We also show that in bilinear groups the size of the public-key can be shrunk from n to $2\\\\sqrt{n}$ group elements, where n is the security parameter.\",\n \"Title: Threshold circuit lower bounds on cryptographic functions\\nYear: 2005\\n\\nAbstract: In this work, we are interested in non-trivial upper bounds on the spectral norm of binary matrices M from {-1,1}^N^x^N. It is known that the distributed Boolean function represented by M is hard to compute in various restricted models of computation if the spectral norm is bounded from above by N^1^-^@?, where @?0 denotes a fixed constant. For instance, the size of a two-layer threshold circuit (with polynomially bounded weights for the gates in the hidden layer, but unbounded weights for the output gate) grows exponentially fast with n@?logN. We prove sufficient conditions on M that imply small spectral norms (and thus high computational complexity in restricted models). Our general results cover specific cases, where the matrix M represents a bit (the least significant bit or other fixed bits) of fundamental functions. Functions like the discrete multiplication and division, as well as cryptographic functions such as the Diffie-Hellman function (IEEE Trans. Inform. Theory 22(6) (1976) 644-654) and the decryption functions of the Pointcheval (Advances in Cryptology-Proceedings of EUROCRYPT '99, Lecture Notes in Computer Science, Springer, Berlin, 1999, pp. 239-254) and the El Gamal (Advances in Cryptology-CRYPTO '84, 1984, pp. 10-18) cryptosystems can be addressed by our technique. In order to obtain our results, we make a detour on exponential sums and on spectral norms of matrices with complex entries. This method might be considered interesting in its own right.\",\n \"Title: Some (in)sufficient conditions for secure hybrid encryption\\nYear: 2006\\n\\nAbstract: In hybrid public key encryption (PKE), first a key encapsulation mechanism (KEM) is used to fix a random session key that is then fed into a highly efficient data encapsulation mechanism (DEM) to encrypt the actual message. A well-known composition theorem states that if both the KEM and the DEM have a high enough level of security (i.e., security against chosen-ciphertext attacks), then so does the hybrid PKE scheme. It is not known if these strong security requirements on the KEM and DEM are also necessary, nor if such general composition theorems exist for weaker levels of security. Using six different security notions for KEMs, 10 for DEMs, and six for PKE schemes, we completely characterize in this work which combinations lead to a secure hybrid PKE scheme (by proving a composition theorem) and which do not (by providing counterexamples). Furthermore, as an independent result, we revisit and extend prior work on the relations among security notions for KEMs and DEMs.\",\n \"Title: Unconditionally secure constant-rounds multi-party computation for equality, comparison, bits and exponentiation\\nYear: 2006\\n\\nAbstract: We show that if a set of players hold shares of a value $a \\\\in \\\\mathbb{F}_p $ for some prime p (where the set of shares is written [a]p), it is possible to compute, in constant rounds and with unconditional security, sharings of the bits of a, i.e., compute sharings [a0]p, ..., [aℓ−−1]p such that ℓ = ⌈ log2p ⌉, a0,...,al−1∈{0,1} and a = ∑i=0ℓ−−1ai 2i. Our protocol is secure against active adversaries and works for any linear secret sharing scheme with a multiplication protocol. The complexity of our protocol is $\\\\mathcal{O}(l {\\\\rm log} l)$ invocations of the multiplication protocol for the underlying secret sharing scheme, carried out in $\\\\mathcal{O}(1)$ rounds. This result immediately implies solutions to other long-standing open problems such as constant-rounds and unconditionally secure protocols for deciding whether a shared number is zero, comparing shared numbers, raising a shared number to a shared exponent and reducing a shared number modulo a shared modulus.\",\n \"Title: The Kurosawa--Desmedt key encapsulation is not chosen-ciphertext secure\\nYear: 2009\\n\\nAbstract: At CRYPTO 2004, Kurosawa and Desmedt presented a new hybrid encryption scheme that is chosen-ciphertext (CCA2) secure in the standard model. Until now it was unknown if the key encapsulation part of the Kurosawa-Desmedt scheme by itself is still CCA2-secure or not. In this note we answer this question to the negative, namely we present a simple CCA2 attack on the Kurosawa-Desmedt key encapsulation mechanism. Our attack further supports the design paradigm of Kurosawa and Desmedt to build CCA2-secure hybrid encryption from weak key encapsulation.\",\n \"Title: Secure computation of the mean and related statistics\\nYear: 2005\\n\\nAbstract: In recent years there has been massive progress in the development of technologies for storing and processing of data. If statistical analysis could be applied to such data when it is distributed between several organisations, there could be huge benefits. Unfortunately, in many cases, for legal or commercial reasons, this is not possible. The idea of using the theory of multi-party computation to analyse efficient algorithms for privacy preserving data-mining was proposed by Pinkas and Lindell. The point is that algorithms developed in this way can be used to overcome the apparent impasse described above: the owners of data can, in effect, pool their data while ensuring that privacy is maintained. Motivated by this, we describe how to securely compute the mean of an attribute value in a database that is shared between two parties. We also demonstrate that existing solutions in the literature that could be used to do this leak information, therefore underlining the importance of applying rigorous theoretical analysis rather than settling for ad hoc techniques.\",\n \"Title: Programmable Hash Functions and Their Applications\\nYear: 2011\\n\\nAbstract: We introduce a new information-theoretic primitive called programmable hash functions (PHFs). PHFs can be used to program the output of a hash function such that it contains solved or unsolved discrete logarithm instances with a certain probability.\\n This is a technique originally used for security proofs in the random oracle model. We give a variety of standard model realizations of PHFs (with different parameters).\\n \\n The programmability of PHFs make them a suitable tool to obtain black-box proofs of cryptographic protocols when considering\\n adaptive attacks. We propose generic digital signature schemes from the strong RSA problem and from some hardness assumption\\n on bilinear maps that can be instantiated with any PHF. Our schemes offer various improvements over known constructions. In\\n particular, for a reasonable choice of parameters, we obtain short standard model digital signatures over bilinear maps.\",\n \"Title: Chosen-ciphertext secure threshold identity-based key encapsulation without random oracles\\nYear: 2006\\n\\nAbstract: We describe the first identity-based key encapsulation mechanism with threshold key delegation and decapsulation that is secure in the standard model against chosen-ciphertext (CCA2) attacks. Our scheme is unconditionally consistent and proved secure under the Bilinear Decisional Diffie-Hellman assumption.\",\n \"Title: DDH-Like assumptions based on extension rings\\nYear: 2012\\n\\nAbstract: We introduce and study a new type of DDH-like assumptions based on groups of prime order q . Whereas standard DDH is based on encoding elements of $\\\\mathbb{F}_{q}$ \\\"in the exponent\\\" of elements in the group, we ask what happens if instead we put in the exponent elements of the extension ring $R_f= \\\\mathbb{F}_{q}[X]/(f)$ where f is a degree-d polynomial. The decision problem that follows naturally reduces to the case where f is irreducible. This variant is called the d -DDH problem, where 1-DDH is standard DDH. We show in the generic group model that d -DDH is harder than DDH for d 1 and that we obtain, in fact, an infinite hierarchy of progressively weaker assumptions whose complexities lie \\\"between\\\" DDH and CDH. This leads to a large number of new schemes because virtually all known DDH-based constructions can very easily be upgraded to be based on d -DDH. We use the same construction and security proof but get better security and moreover, the amortized complexity (e.g, computation per encrypted bit) is the same as when using DDH. We also show that d -DDH, just like DDH, is easy in bilinear groups. We therefore suggest a different type of assumption, the d -vector DDH problems (d -VDDH), which are based on f (X )=X d , but with a twist to avoid problems with reducible polynomials. We show in the generic group model that d -VDDH is hard in bilinear groups and that the problems become harder with increasing d . We show that hardness of d -VDDH implies CCA-secure encryption, efficient Naor-Reingold style pseudorandom functions, and auxiliary input secure encryption. This can be seen as an alternative to the known family of k -LIN assumptions.\",\n \"Title: Subtleties in the Definition of IND-CCA: When and How Should Challenge Decryption Be Disallowed?\\nYear: 2009\\n\\nAbstract: IND-CCA (indistinguishability under adaptive chosen-ciphertext attacks) is a central notion of security for public-key encryption, defined and targeted in many papers. Non-triviality of the notion requires that the adversary not query the challenge ciphertext to the decryption oracle. We point out that this \\\\\\\"no-challenge-decryption\\\\\\\" condition can be formalized in several different ways and the literature is not consistent, sometimes doing it one way, sometimes another, and assuming it makes no difference. We show that the latter perception is incorrect. It does make a difference, for the resulting notions are not equivalent. Specifically, we consider four notions corresponding to whether challenge decryption is disallowed in both phases of the adversary's attack or just in the second, and, orthogonally, whether the disallowance is \\\\\\\"penalty\\\\\\\" or \\\\\\\"exclusion\\\\\\\" based. We show that the notions are not all equivalent for public-key encryption (PKE). We then show that, in contrast, they are equivalent for key-encapsulation mechanisms (KEMs). Our work shows that subtle foundational issues exist even with notions that are supposedly well-established and unambiguous, and highlights the need to be careful and precise with regard to \\\\\\\"minor\\\\\\\" definitional \\\\\\\"details\\\\\\\".\",\n \"Title: Chosen-Ciphertext Secure Identity-Based Encryption in the Standard Model with short Ciphertexts\\nYear: 2006\\n\\nAbstract: We describe a practical identity-based encryption scheme that is secure in the standard model against chosen-ciphertext (CCA2) attacks. Security is based on an assumption comparable to (but slightly stronger than) Bilinear Decisonal Die-Hellman (BDDH). A comparison shows that our construction outperforms all known identity-based encryption schemes in the standard model and its performance is even comparable with the one from the random-oracle based Boneh/Franklin IBE scheme. Our proposed IBE scheme has furthermore the property that it fulfills some notion of \\\"redundancy-freeness\\\", i.e. the encryption algorithm is not only a probabilistic injection but also a surjection. As a consequence the ciphertext overhead is nearly optimal: to encrypt k bit messages for k bit identities and with k bit randomness we get 3k bit ciphertexts to guarantee (roughly) k bits of security. Keywords: Chosen-ciphertext security, Identity-Based Encryption, Bilinear Maps.\",\n \"Title: Instantiability of RSA-OAEP under chosen-plaintext attack\\nYear: 2010\\n\\nAbstract: We show that the widely deployed RSA-OAEP encryption scheme of Bellare and Rogaway (Eurocrypt 1994), which combines RSA with two rounds of an underlying Feistel network whose hash (i.e., round) functions are modeled as random oracles, meets indistinguishability under chosen-plaintext attack (IND-CPA) in the standard model based on simple, non-interactive, and non-interdependent assumptions on RSA and the hash functions. To prove this, we first give a result on a more general notion called \\\"padding-based\\\" encryption, saying that such a scheme is IND-CPA if (1) its underlying padding transform satisfies a \\\"fooling\\\" condition against small-range distinguishers on a class of high-entropy input distributions, and (2) its trapdoor permutation is sufficiently lossy as defined by Peikert and Waters (STOC 2008). We then show that the first round of OAEP satifies condition (1) if its hash function is t-wise independent for appopriate t and that RSA satisfies condition (2) under the φ-Hiding Assumption of Cachin et al. (Eurocrypt 1999). This appears to be the first non-trivial positive result about the instantiability of RSA-OAEP. In particular, it increases our confidence that chosen-plaintext attacks are unlikely to be found against the scheme. In contrast, RSA-OAEP's predecessor in PKCS #1 v1.5 was shown to be vulnerable to such attacks by Coron et al. (Eurocrypt 2000).\",\n \"Title: Secure hybrid encryption from weakened key encapsulation\\nYear: 2007\\n\\nAbstract: We put forward a new paradigm for building hybrid encryption schemes from constrained chosen-ciphertext secure (CCCA) key-encapsulation mechanisms (KEMs) plus authenticated symmetric encryption. Constrained chosen-ciphertext security is a new security notion for KEMs that we propose. It has less demanding security requirements than standard CCCA security (since it requires the adversary to have a certain plaintext-knowledge when making a decapsulation query) yet we can prove that it is CCCA sufficient for secure hybrid encryption. Our notion is not only useful to express the Kurosawa-Desmedt public-key encryption scheme and its generalizations to hash-proof systems in an abstract KEM/DEM security framework. It also has a very constructive appeal, which we demonstrate with a new encryption scheme whose security relies on a class of intractability assumptions that we show (in the generic group model) strictly weaker than the Decision Diffie-Hellman (DDH) assumption. This appears to be the first practical public-key encryption scheme in the literature from an algebraic assumption strictly weaker than DDH.\",\n \"Title: Direct chosen-ciphertext secure identity-based key encapsulation without random oracles\\nYear: 2006\\n\\nAbstract: We describe a practical identity-based encryption scheme that is secure in the standard model against chosen-ciphertext attacks. Our construction applies ''direct chosen-ciphertext techniques'' to Waters' chosen-plaintext secure scheme and is not based on hierarchical identity-based encryption. Furthermore, we give an improved concrete security analysis for Waters' scheme. As a result, one can instantiate the scheme in smaller groups, resulting in efficiency improvements.\",\n \"Title: Adaptive trapdoor functions and chosen-ciphertext security\\nYear: 2010\\n\\nAbstract: We introduce the notion of adaptive trapdoor functions (ATDFs); roughly, ATDFs remain one-way even when the adversary is given access to an inversion oracle. Our main application is the black-box construction of chosen-ciphertext secure public-key encryption (CCA-secure PKE). Namely, we give a black-box construction of CCA-Secure PKE from ATDFs, as well as a construction of ATDFs from correlation-secure TDFs introduced by Rosen and Segev (TCC ’09). Moreover, by an extension of a recent result of Vahlis (TCC ’10), we show that ATDFs are strictly weaker than the latter (in a black-box sense). Thus, adaptivity appears to be the weakest condition on a TDF currently known to yield the first implication. We also give a black-box construction of CCA-secure PKE from a natural extension of ATDFs we call tag-based ATDFs that, when applied to our constructions of the latter from either correlation-secure TDFs, or lossy TDFs introduced by Peikert and Waters (STOC ’08), yield precisely the CCA-secure PKE schemes in these works. This helps to unify and clarify their schemes. Finally, we show how to realize tag-based ATDFs from an assumption on RSA inversion not known to yield correlation-secure TDFs.\",\n \"Title: A Primitive for Proving the Security of Every Bit and About Universal Hash Functions & Hard Core Bits\\nYear: 2001\\n\\nAbstract: We present a useful primitive, the hidden number problem, which can be exploited to prove that every bit is a hard core of specific cryptographic functions. Applications are RSA, ElGamal, Rabin and others. We give an efficient construction of a hard core predicate of any one-way function providing an alternative to the famous Goldreich-Levin Bit [3]. Furthermore, a conjectured connection between universal hash functions and hard core predicates is disproven.\",\n \"Title: The Twin Diffie–Hellman Problem and Applications\\nYear: 2009\\n\\nAbstract: We propose a new computational problem called the twin Diffie–Hellman problem. This problem is closely related to the usual (computational) Diffie–Hellman problem and can be used in many of the same cryptographic constructions that are based on the Diffie–Hellman problem. Moreover, the twin Diffie–Hellman problem is at least as hard as the ordinary Diffie–Hellman problem. However, we are able to show that the twin Diffie–Hellman problem remains hard, even in the presence of a decision oracle that recognizes solutions to the problem—this is a feature not enjoyed by the Diffie–Hellman problem, in general. Specifically, we show how to build a certain “trapdoor test” that allows us to effectively answer decision oracle queries for the twin Diffie–Hellman problem without knowing any of the corresponding discrete logarithms. Our new techniques have many applications. As one such application, we present a new variant of ElGamal encryption with very short ciphertexts, and with a very simple and tight security proof, in the random oracle model, under the assumption that the ordinary Diffie–Hellman problem is hard. We present several other applications as well, including a new variant of Diffie and Hellman’s non-interactive key exchange protocol; a new variant of Cramer–Shoup encryption, with a very simple proof in the standard model; a new variant of Boneh–Franklin identity-based encryption, with very short ciphertexts; a more robust version of a password-authenticated key exchange protocol of Abdalla and Pointcheval.\",\n \"Title: Efficient hybrid encryption from ID-based encryption\\nYear: 2007\\n\\nAbstract: This paper deals with generic transformations from ID-based key encapsulation mechanisms (IBKEM) to hybrid public-key encryption (PKE). The best generic transformation known until now is by Boneh and Katz and requires roughly 704-bit overhead in the ciphertext. We present new generic transformations that are applicable to partitioned IBKEMs. A partitioned IBKEM is an IBKEM that provides some extra structure. Such IBKEMs are quite natural and in fact nearly all known IBKEMs have this additional property. Our first transformation yields chosen-ciphertext secure PKE schemes from selective-ID secure partitioned IBKEMs with a 256-bit overhead in ciphertext size plus one extra exponentiation in encryption/decryption. As the central tool a Chameleon Hash function is used to map the identities. We also propose other methods to remove the use of Chameleon Hash, which may be of independent technical interest. Applying our transformations to existing IBKEMs we propose a number of novel PKE schemes with different trade-offs. In some concrete instantiations the Chameleon Hash can be made \\\"implicit\\\" which results in improved efficiency by eliminating the additional exponentiation. Since our transformations preserve the public verifiability property of the IBE schemes it is possible to extend our results to build threshold hybrid PKE schemes. We show an analogue generic transformation in the threshold setting and present a concrete scheme which results in the most efficient threshold PKE scheme in the standard model.\",\n \"Title: Compact CCA-Secure Encryption for Messages of Arbitrary Length\\nYear: 2009\\n\\nAbstract: This paper proposes a chosen-ciphertext secure variant of the ElGamal public-key encryption scheme which generates very compact ciphertexts for messages of arbitrary length . The ciphertext overhead (i.e., the difference between ciphertext and plaintext) is one group element only. Such a property is particularly useful when encrypting short messages such as a PIN or a credit card number in bandwidth-critical environments. On top of the compact overhead, the computational cost for encryption and decryption are almost the same as plain ElGamal encryption. The security is proven based on the strong Diffie-Hellman assumption in the random oracle model.\",\n \"Title: Polynomial interpolation of cryptographic functions related to Diffie-Hellman and discrete logarithm problem\\nYear: 2006\\n\\nAbstract: Recently, the first author introduced some cryptographic functions closely related to the Diffie-Hellman problem called P- Diffie-Hellman functions. We show that the existence of a low-degree polynomial representing a P-Diffie-Hellman function on a large set would lead to an efficient algorithm for solving the Diffie-Hellman problem. Motivated by this result we prove lower bounds on the degree of such interpolation polynomials. Analogously, we introduce a class of functions related to the discrete logarithm and show similar reduction and interpolation results.\",\n \"Title: Chosen-Ciphertext security from tag-based encryption\\nYear: 2006\\n\\nAbstract: One of the celebrated applications of Identity-Based Encryption (IBE) is the Canetti, Halevi, and Katz (CHK) transformation from any (selective-identity secure) IBE scheme into a full chosen-ciphertext secure encryption scheme. Since such IBE schemes in the standard model are known from previous work this immediately provides new chosenciphertext secure encryption schemes in the standard model. This paper revisits the notion of Tag-Based Encryption (TBE) and provides security definitions for the selective-tag case. Even though TBE schemes belong to a more general class of cryptographic schemes than IBE, we observe that (selective-tag secure) TBE is a su.cient primitive for the CHK transformation and therefore implies chosen-ciphertext secure encryption. We construct efficient and practical TBE schemes and give tight security reductions in the standard model from the Decisional Linear Assumption in gap-groups. In contrast to all known IBE schemes our TBE construction does not directly deploy pairings. Instantiating the CHK transformation with our TBE scheme results in an encryption scheme whose decryption can be carried out in one single multi-exponentiation. Furthermore, we show how to apply the techniques gained from the TBE construction to directly design a new Key Encapsulation Mechanism. Since in this case we can avoid the CHK transformation the scheme results in improved efficiency.\",\n \"Title: On the Security of Padding-Based Encryption Schemes --- or --- Why We Cannot Prove OAEP Secure in the Standard Model\\nYear: 2009\\n\\nAbstract: We investigate the security of \\\"padding-based\\\" encryption schemes in the standard model. This class contains all public-key encryption schemes where the encryption algorithm first applies some invertible public transformation to the message (the \\\"padding\\\"), followed by a trapdoor permutation. In particular, this class contains OAEP and its variants. Our main result is a black-box impossibility result showing that one cannot prove any such padding-based scheme chosen-ciphertext secure even assuming the existence of ideal trapdoor permutations. The latter is a strong ideal abstraction of trapdoor permutations which inherits all security properties of uniform random permutations.\",\n \"Title: Chosen Ciphertext Security with Optimal Ciphertext Overhead\\nYear: 2008\\n\\nAbstract: Every public-key encryption scheme has to incorporate a certain amount of randomness into its ciphertexts to provide semantic security against chosen ciphertext attacks (IND-CCA). The difference between the length of a ciphertext and the embedded message is called the ciphertext overhead . While a generic brute-force adversary running in 2 t steps gives a theoretical lower bound of t bits on the ciphertext overhead for IND-CPA security, the best known IND-CCA secure schemes demand roughly 2t bits even in the random oracle model. Is the t -bit gap essential for achieving IND-CCA security? We close the gap by proposing an IND-CCA secure scheme whose ciphertext overhead matches the generic lower bound up to a small constant. Our scheme uses a variation of a four-round Feistel network in the random oracle model and hence belongs to the family of OAEP-based schemes. Maybe of independent interest is a new efficient method to encrypt long messages exceeding the length of the permutation while retaining the minimal overhead.\",\n \"Title: Identity-Based (lossy) trapdoor functions and applications\\nYear: 2012\\n\\nAbstract: We provide the first constructions of identity-based (injective) trapdoor functions. Furthermore, they are lossy. Constructions are given both with pairings (DLIN) and lattices (LWE). Our lossy identitybased trapdoor functions provide an automatic way to realize, in the identity-based setting, many functionalities previously known only in the public-key setting. In particular we obtain the first deterministic and efficiently searchable IBE schemes and the first hedged IBE schemes, which achieve best possible security in the face of bad randomness. Underlying our constructs is a new definition, namely partial lossiness, that may be of broader interest.\",\n \"Title: Searchable Encryption Revisited: Consistency Properties, Relation to Anonymous IBE, and Extensions\\nYear: 2005\\n\\nAbstract: We identify and fill some gaps with regard to consistency (the extent to which false positives are produced) for public-key encryption with keyword search (PEKS). We define computational and statistical relaxations of the existing notion of perfect consistency, show that the scheme of Boneh et al. (Advances in Cryptology—EUROCRYPT 2004, ed. by C. Cachin, J. Camenisch, pp. 506–522, 2004) is computationally consistent, and provide a new scheme that is statistically consistent. We also provide a transform of an anonymous identity-based encryption (IBE) scheme to a secure PEKS scheme that, unlike the previous one, guarantees consistency. Finally, we suggest three extensions of the basic notions considered here, namely anonymous hierarchical identity-based encryption, public-key encryption with temporary keyword search, and identity-based encryption with keyword search.\",\n \"Title: Digital Signatures with Minimal Overhead from Indifferentiable Random Invertible Functions.\\nYear: 2013\\n\\nAbstract: In a digital signature scheme with message recovery, rather than transmitting the message m and its signature sigma, a single enhanced signature tau is transmitted. The verifier is able to recover m from tau and at the same time verify its authenticity. The two most important parameters of such a scheme are its security and overhead vertical bar tau vertical bar - vertical bar m vertical bar. A simple argument shows that for any scheme with \\\"n bits security\\\" vertical bar tau vertical bar - vertical bar m vertical bar >= n, i.e., the overhead is lower bounded by the security parameter n. Currently, the best known constructions in the random oracle model are far from this lower bound requiring an overhead of n + logq(h), where q(h) is the number of queries to the random oracle. In this paper we give a construction which basically matches the n bit lower bound. We propose a simple digital signature scheme with n + o(log q(h)) bits overhead, where q(h) denotes the number of random oracle queries. Our construction works in two steps. First, we propose a signature scheme with message recovery having optimal overhead in a new ideal model, the random invertible function model. Second, we show that a four-round Feistel network with random oracles as round functions is tightly \\\"public-indifferentiable\\\" from a random invertible function. At the core of our indifferentiability proof is an almost tight upper bound for the expected number of edges of the densest \\\"small\\\" subgraph of a random Cayley graph, which may be of independent interest.\",\n \"Title: CCA2 secure IBE: standard model efficiency through authenticated symmetric encryption\\nYear: 2008\\n\\nAbstract: We propose two constructions of chosen-ciphertext secure identity-based encryption (IBE) schemes. Our schemes have a security proof in the standard model, yet they offer performance competitive with all known random-oracle based schemes. The efficiency improvement is obtained by combining modifications of the IBE schemes by Waters [38] and Gentry [21] with authenticated symmetric encryption.\",\n \"Title: Public-key encryption with non-interactive opening\\nYear: 2008\\n\\nAbstract: We formally define the primitive of public-key encryption with non-interactive opening (PKENO), where the receiver of a cipher-text C can, convincingly and without interaction, reveal what the result was of decrypting C, without compromising the scheme's security. This has numerous applications in cryptographic protocol design, e.g., when the receiver wants to demonstrate that some information he was sent privately was not correctly formed. We give a definition based on the UC framework as well as an equivalent game-based definition. The PKENO concept was informally introduced by Damgård and Thorbek who suggested that it could be implemented based on Identity-Based Encryption. In this paper, we give direct and optimized implementations, that work without having to keep state information, unlike what one obtains from directly using IBE.\",\n \"Title: Short signatures from weaker assumptions\\nYear: 2011\\n\\nAbstract: We provide constructions of (m,1)-programmable hash functions (PHFs) for m≥2. Mimicking certain programmability properties of random oracles, PHFs can, e.g., be plugged into the generic constructions by Hofheinz and Kiltz (J. Cryptol. 2011) to yield digital signature schemes from the strong RSA and strong q-Diffie-Hellman assumptions. As another application of PHFs, we propose new and efficient constructions of digital signature schemes from weaker assumptions, i.e., from the (standard, non-strong) RSA and the (standard, non-strong) q-Diffie-Hellman assumptions. The resulting signature schemes offer interesting tradeoffs between efficiency/signature length and the size of the public-keys. For example, our q-Diffie-Hellman signatures can be as short as 200 bits; the signing algorithm of our Strong RSA signature scheme can be as efficient as the one in RSA full domain hash; compared to previous constructions, our RSA signatures are shorter (by a factor of roughly 2) and we obtain a considerable efficiency improvement (by an even larger factor). All our constructions are in the standard model, i.e., without random oracles.\",\n \"Title: Optimal security proofs for full domain hash, revisited\\nYear: 2012\\n\\nAbstract: RSA Full Domain Hash (RSA-FDH) is a digital signature scheme, secure again chosen message attacks in the random oracle model. The best known security reduction from the RSA assumption is nontight, i.e., it loses a factor of qs, where qs is the number of signature queries made by the adversary. It was furthermore proved by Coron (EUROCRYPT 2002) that a security loss of qs is optimal and cannot possibly be improved. In this work we uncover a subtle flaw in Coron's impossibility result. Concretely, we show that it only holds if the underlying trapdoor permutation is certified. Since it is well known that the RSA trapdoor permutation is (for all practical parameters) not certified, this renders Coron's impossibility result moot for RSA-FDH. Motivated by this, we revisit the question whether there is a tight security proof for RSA-FDH. Concretely, we give a new tight security reduction from a stronger assumption, the Phi-Hiding assumption introduced by Cachin et al (EUROCRYPT 1999). This justifies the choice of smaller parameters in RSA-FDH, as it is commonly used in practice. All of our results (positive and negative) extend to the probabilistic signature scheme PSS.\",\n \"Title: On the Representation of Boolean Predicates of the Diffie-Hellman Function\\nYear: 2003\\n\\nAbstract: In this work we give a non-trivial upper bound on the spectral norm of various Boolean predicates of the Diffie-Hellman function. For instance, we consider every individual bit and arbitrary unbiased intervals. Combining the bound with recent results from complexity theory we can rule out the possibility that such a Boolean function can be represented by simple functions like depth-2 threshold circuits with a small number of gates.\",\n \"Title: Bonsai Trees, or How to Delegate a Lattice Basis\\nYear: 2010\\n\\nAbstract: We introduce a new lattice-based cryptographic structure called a bonsai tree, and use it to resolve some important open problems in the area. Applications of bonsai trees include an efficient, stateless `hash-and-sign' signature scheme in the standard model (i.e., no random oracles), and the first hierarchical identity-based encryption (HIBE) scheme (also in the standard model) that does not rely on bilinear pairings. Interestingly, the abstract properties of bonsai trees seem to have no known realization in conventional number-theoretic cryptography.\",\n \"Title: The Group of Signed Quadratic Residues and Applications\\nYear: 2009\\n\\nAbstract: We consider the cryptographic group of Signed Quadratic Residues. This group is particularly useful for cryptography since it is a \\\"gap-group,\\\" in which the computational problem (i.e., computing square roots) is as hard as factoring, while the corresponding decisional problem (i.e., recognizing signed quadratic residues) is easy. We are able to show that under the factoring assumption, the Strong Diffie-Hellman assumption over the signed quadratic residues holds. That is, in this group the Diffie-Hellman problem is hard, even in the presence of a Decisional Diffie-Hellman oracle.We demonstrate the usefulness of our results by applying them to the Hybrid ElGamal encryption scheme (aka Diffie-Hellman integrated encryption scheme - DHIES). Concretely, we consider the security of the scheme when instantiated over the group of signed quadratic residues. It is known that, in the random oracle model, the scheme is chosenciphertext (CCA) secure under the Strong Diffie-Hellman assumption and hence, by our results, under the standard factoring assumption. We show that furthermore, in the standard model, Hybrid ElGamal is CCA secure under the higher residuosity assumption, given that the used hash function is four-wise independent. The latter result is obtained using the recent \\\"randomness extraction framework\\\" for hash proof systems.\",\n \"Title: A Tool Box of Cryptographic Functions Related to the Diffie-Hellman Function\\nYear: 2001\\n\\nAbstract: Given a cyclic group G and a generator g, the Diffie-Hellman function (DH) maps two group elements (ga, gb) to gab. For many groups G this function is assumed to be hard to compute. We generalize this function to the P-Diffie-Hellman function (P-DH) that maps two group elements (ga, gb) to gP(a,b) for a (non-linear) polynomial P in a and b. In this paper we show that computing DH is computationally equivalent to computing P-DH. In addition we study the corresponding decision problem. In sharp contrast to the computational case the decision problems for DH and P-DH can be shown to be not generically equivalent for most polynomials P. Furthermore we show that there is no generic algorithm that computes or decides the P-DH function in polynomial time.\",\n \"Title: A note on secure computation of the moore-penrose pseudoinverse and its application to secure linear algebra\\nYear: 2007\\n\\nAbstract: This work deals with the communication complexity of secure multi-party protocols for linear algebra problems. In our model, complexity is measured in terms of the number of secure multiplications required and protocols terminate within a constant number of rounds of communication. Previous work by Cramer and Damgård proposes secure protocols for solving systems Ax = b of m linear equations in n variables over a finite field, with m ≤ n. The complexity of those protocols is n5. We show a new upper bound of m4 + n2m secure multiplications for this problem, which is clearly asymptotically smaller. Our main point, however, is that the advantage can be substantial in case m is much smaller than n. Indeed, if m = √n, for example, the complexity goes down from n5 to n2.5. Our secure protocols rely on some recent advances concerning the computation of the Moore-Penrose pseudo-inverse of matrices over fields of positive characteristic. These computations are based on the evaluation of a certain characteristic polynomial, in combination with variations on a well-known technique due to Mulmuley that helps to control the effects of non-zero characteristic. We also introduce a new method for secure polynomial evaluation that exploits properties of Chebychev polynomials, as well as a new secure protocol for computing the characteristic polynomial of a matrix based on Leverrier's lemma that exploits this new method.\",\n \"Title: Efficient authentication from hard learning problems\\nYear: 2011\\n\\nAbstract: We construct efficient authentication protocols and message-authentication codes (MACs) whose security can be reduced to the learning parity with noise (LPN) problem. Despite a large body of work - starting with the HB protocol of Hopper and Blum in 2001 - until now it was not even known how to construct an efficient authentication protocol from LPN which is secure against man-in-the-middle (MIM) attacks. A MAC implies such a (two-round) protocol.\",\n \"Title: A New Randomness Extraction Paradigm for Hybrid Encryption\\nYear: 2009\\n\\nAbstract: We present a new approach to the design of IND-CCA2 secure hybrid encryption schemes in the standard model. Our approach provides an efficient generic transformation from 1-universal to 2-universal hash proof systems. The transformation involves a randomness extractor based on a 4-wise independent hash function as the key derivation function. Our methodology can be instantiated with efficient schemes based on standard intractability assumptions such as Decisional Diffie-Hellman, Quadratic Residuosity, and Paillier's Decisional Composite Residuosity. Interestingly, our framework also allows to prove IND-CCA2 security of a hybrid version of 1991's Damgård's ElGamal public-key encryption scheme under the DDH assumption.\",\n \"Title: Practical Chosen Ciphertext Secure Encryption from Factoring\\nYear: 2013\\n\\nAbstract: We propose a practical public-key encryption scheme whose security against chosen-ciphertext attacks can be reduced in the standard model to the assumption that factoring is intractable.\",\n \"Title: Chosen-ciphertext secure key-encapsulation based on gap hashed Diffie-Hellman\\nYear: 2007\\n\\nAbstract: We propose a practical key encapsulation mechanism with a simple and intuitive design concept. Security against chosen-ciphertext attacks can be proved in the standard model under a new assumption, the Gap Hashed Diffie-Hellman (GHDH) assumption. The security reduction is tight and simple. Secure key encapsulation, combined with an appropriately secure symmetric encryption scheme, yields a hybrid public-key encryption scheme which is secure against chosen-ciphertext attacks. The implied encryption scheme is very efficient: compared to the previously most efficient scheme by Kurosawa and Desmedt [Crypto 2004] it has 128 bits shorter ciphertexts, between 25-50% shorter public/secret keys, and it is slightly more efficient in terms of encryption/decryption speed. Furthermore, our scheme enjoys (the option of) public verifiability of the ciphertexts and it inherits all practical advantages of secure hybrid encryption.\",\n \"Title: Encryption schemes secure against chosen-ciphertext selective opening attacks\\nYear: 2010\\n\\nAbstract: Imagine many small devices send data to a single receiver, encrypted using the receiver’s public key. Assume an adversary that has the power to adaptively corrupt a subset of these devices. Given the information obtained from these corruptions, do the ciphertexts from uncorrupted devices remain secure? Recent results suggest that conventional security notions for encryption schemes (like IND-CCA security) do not suffice in this setting. To fill this gap, the notion of security against selective-opening attacks (SOA security) has been introduced. It has been shown that lossy encryption implies SOA security against a passive, i.e., only eavesdropping and corrupting, adversary (SO-CPA). However, the known results on SOA security against an active adversary (SO-CCA) are rather limited. Namely, while there exist feasibility results, the (time and space) complexity of currently known SO-CCA secure schemes depends on the number of devices in the setting above. In this contribution, we devise a new solution to the selective opening problem that does not build on lossy encryption. Instead, we combine techniques from non-committing encryption and hash proof systems with a new technique (dubbed “cross-authentication codes”) to glue several ciphertext parts together. The result is a rather practical SO-CCA secure public-key encryption scheme that does not suffer from the efficiency drawbacks of known schemes. Since we build upon hash proof systems, our scheme can be instantiated using standard number-theoretic assumptions such as decisional Diffie-Hellman DDH), decisional composite residuosity (DCR), and quadratic residuosity (QR). Besides, we construct a conceptually very simple and comparatively efficient SO-CPA secure scheme from (slightly enhanced) trapdoor one-way permutations. We stress that our schemes are completely independent of the number of challenge ciphertexts, and we do not make assumptions about the underlying message distribution (beyond being efficiently samplable). In particular, we do not assume efficient conditional re-samplability of the message distribution. Hence, our schemes are secure in arbitrary settings, even if it is not known in advance how many ciphertexts might be considered for corruptions.\",\n \"Title: Quasi-Adaptive NIZK for Linear Subspaces Revisited.\\nYear: 2015\\n\\nAbstract: Non-interactive zero-knowledge (NIZK) proofs for algebraic relations in a group, such as the Groth-Sahai proofs, are an extremely powerful tool in pairing-based cryptography. A series of recent works focused on obtaining very efficient NIZK proofs for linear spaces in a weaker quasi-adaptive model. We revisit recent quasi-adaptive NIZK constructions, providing clean, simple, and improved constructions via a conceptually different approach inspired by recent developments in identity-based encryption. We then extend our techniques also to linearly homomorphic structure-preserving signatures, an object both of independent interest and with many applications.\",\n \"Title: (Hierarchical) Identity-Based Encryption from Affine Message Authentication.\\nYear: 2014\\n\\nAbstract: We provide a generic transformation from any affine message authentication code (MAC) to an identity-based encryption (IBE) scheme over pairing groups of prime order. If the MAC satisfies a security notion related to unforgeability against chosen-message attacks and, for example, the k-Linear assumption holds, then the resulting IBE scheme is adaptively secure. Our security reduction is tightness preserving, i.e., if the MAC has a tight security reduction so has the IBE scheme. Furthermore, the transformation also extends to hierarchical identity-based encryption (HIBE). We also show how to construct affine MACs with a tight security reduction to standard assumptions. This, among other things, provides the first tightly secure HIBE in the standard model.\",\n \"Title: Tightly Secure CCA-Secure Encryption without Pairings.\\nYear: 2016\\n\\nAbstract: We present the first CCA-secure public-key encryption scheme based on DDH where the security loss is independent of the number of challenge ciphertexts and the number of decryption queries. Our construction extends also to the standard k-Lin assumption in pairing-free groups, whereas all prior constructions starting with Hofheinz and Jager (Crypto ’12) rely on the use of pairings. Moreover, our construction improves upon the concrete efficiency of existing schemes, reducing the ciphertext overhead by about half (to only 3 group elements under DDH), in addition to eliminating the use of pairings. We also show how to use our techniques in the NIZK setting. Specifically, we construct the first tightly simulation-sound designated-verifier NIZK for linear languages without pairings. Using pairings, we can turn our construction into a highly optimized publicly verifiable NIZK with tight simulation-soundness.\",\n \"Title: Optimal Security Proofs for Signatures from Identification Schemes.\\nYear: 2016\\n\\nAbstract: We perform a concrete security treatment of digital signature schemes obtained from canonical identification schemes via the Fiat-Shamir transform. If the identification scheme is random self-reducible and satisfies the weakest possible security notion hardness of key-recoverability, then the signature scheme obtained via Fiat-Shamir is unforgeable against chosen-message attacks in the multi-user setting. Our security reduction is in the random oracle model and loses a factor of roughly $$Q_h$$, the number of hash queries. Previous reductions incorporated an additional multiplicative loss of N, the number of users in the system. Our analysis is done in small steps via intermediate security notions, and all our implications have relatively simple proofs. Furthermore, for each step, we show the optimality of the given reduction in terms of model assumptions and tightness. As an important application of our framework, we obtain a concrete security treatment for Schnorr signatures in the multi-user setting.\",\n \"Title: Two-Round Man-in-the-Middle Security from LPN.\\nYear: 2015\\n\\nAbstract: Secret-key authentication protocols have recently received a considerable amount of attention, and a long line of research has been devoted to devising efficient protocols with security based on the hardness of the learning-parity with noise (LPN) problem, with the goal of achieving low communication and round complexities, as well as highest possible security guarantees. In this paper, we construct 2-round authentication protocols that are secure against sequential man-in-the-middle (MIM) attacks with tight reductions to LPN, Field-LPN, or other problems. The best prior protocols had either loose reductions and required 3 rounds (Lyubashevsky and Masny, CRYPTO'13) or had a much larger key (Kiltz et al., EUROCRYPT'11 and Dodis et al., EUROCRYPT'12). Our constructions follow from a new generic deterministic and round-preserving transformation enhancing actively-secure protocols of a special form to be sequentially MIM-secure while only adding a limited amount of key material and computation.\",\n \"Title: Standard Security Does Imply Security Against Selective Opening for Markov Distributions.\\nYear: 2016\\n\\nAbstract: About three decades ago it was realized that implementing private channels between parties which can be adaptively corrupted requires an encryption scheme that is secure against selective opening attacks. Whether standard (IND-CPA) security implies security against selective opening attacks has been a major open question since. The only known reduction from selective opening to IND-CPA security loses an exponential factor. A polynomial reduction is only known for the very special case where the distribution considered in the selective opening security experiment is a product distribution, i.e., the messages are sampled independently from each other. In this paper we give a reduction whose loss is quantified via the dependence graph (where message dependencies correspond to edges) of the underlying message distribution. In particular, for some concrete distributions including Markov distributions, our reduction is polynomial.\",\n \"Title: Tightly CCA-Secure Encryption Without Pairings.\\nYear: 2016\\n\\nAbstract: We present the first CCA-secure public-key encryption scheme based on DDH where the security loss is independent of the number of challenge ciphertexts and the number of decryption queries. Our construction extends also to the standard k-$$\\\\\\\\mathsf {Lin} $$ assumption in pairing-free groups, whereas all prior constructions starting with Hofheinz and Jager Crypto '12 rely on the use of pairings. Moreover, our construction improves upon the concrete efficiency of existing schemes, reducing the ciphertext overhead by about half to only $$3$$ group elements under DDH, in addition to eliminating the use of pairings. We also show how to use our techniques in the NIZK setting. Specifically, we construct the first tightly simulation-sound designated-verifier NIZK for linear languages without pairings. Using pairings, we can turn our construction into a highly optimized publicly verifiable NIZK with tight simulation-soundness.\",\n \"Title: Selective opening security of practical public-key encryption schemes.\\nYear: 2016\\n\\nAbstract: The authors show that two well-known and widely employed public-key encryption schemes - RSA optimal asymmetric encryption padding (RSA-OAEP) and Diffie-Hellman integrated encryption scheme (DHIES), instantiated with a one-time pad, - are secure under (the strong, simulation-based security notion of) selective opening security against chosen-ciphertext attacks in the random oracle model. Both sche...\",\n \"Title: On the Provable Security of (EC)DSA Signatures.\\nYear: 2016\\n\\nAbstract: Among the signature schemes most widely deployed in practice are the DSA (Digital Signature Algorithm) and its elliptic curves variant ECDSA. They are represented in many international standards, including IEEE P1363, ANSI X9.62, and FIPS 186-4. Their popularity stands in stark contrast to the absence of rigorous security analyses: Previous works either study modified versions of (EC)DSA or provide a security analysis of unmodified ECDSA in the generic group model. Unfortunately, works following the latter approach assume abstractions of non-algebraic functions over generic groups for which it remains unclear how they translate to the security of ECDSA in practice. For instance, it has been pointed out that prior results in the generic group model actually establish strong unforgeability of ECDSA, a property that the scheme de facto does not possess. As, further, no formal results are known for DSA, understanding the security of both schemes remains an open problem. In this work we propose GenericDSA, a signature framework that subsumes both DSA and ECDSA in unmodified form. It carefully models the \\\\\\\"modulo q\\\\\\\" conversion function of (EC)DSA as a composition of three independent functions. The two outer functions mimic algebraic properties in the function's domain and range, the inner one is modeled as a bijective random oracle. We rigorously prove results on the security of GenericDSA that indicate that forging signatures in (EC)DSA is as hard as solving discrete logarithms. Importantly, our proofs do not assume generic group behavior.\",\n \"Title: A Modular Analysis of the Fujisaki-Okamoto Transformation.\\nYear: 2017\\n\\nAbstract: The Fujisaki-Okamoto (FO) transformation (CRYPTO 1999 and Journal of Cryptology 2013) turns any weakly secure public-key encryption scheme into a strongly (i.e., (mathsf {IND}text {-}mathsf {CCA})) secure one in the random oracle model. Unfortunately, the FO analysis suffers from several drawbacks, such as a non-tight security reduction, and the need for a perfectly correct scheme. While several alternatives to the FO transformation have been proposed, they have stronger requirements, or do not obtain all desired properties.\",\n \"Title: CRYSTALS - Kyber: A CCA-Secure Module-Lattice-Based KEM\\nYear: 2018\\n\\nAbstract: Rapid advances in quantum computing, together with the announcement by the National Institute of Standards and Technology (NIST) to define new standards for digitalsignature, encryption, and key-establishment protocols, have created significant interest in post-quantum cryptographic schemes. This paper introduces Kyber (part of CRYSTALS - Cryptographic Suite for Algebraic Lattices - a package submitted to NIST post-quantum standardization effort in November 2017), a portfolio of post-quantum cryptographic primitives built around a key-encapsulation mechanism (KEM), based on hardness assumptions over module lattices. Our KEM is most naturally seen as a successor to the NEWHOPE KEM (Usenix 2016). In particular, the key and ciphertext sizes of our new construction are about half the size, the KEM offers CCA instead of only passive security, the security is based on a more general (and flexible) lattice problem, and our optimized implementation results in essentially the same running time as the aforementioned scheme. We first introduce a CPA-secure public-key encryption scheme, apply a variant of the Fujisaki-Okamoto transform to create a CCA-secure KEM, and eventually construct, in a black-box manner, CCA-secure encryption, key exchange, and authenticated-key-exchange schemes. The security of our primitives is based on the hardness of Module-LWE in the classical and quantum random oracle models, and our concrete parameters conservatively target more than 128 bits of postquantum security.\",\n \"Title: Tightly-Secure Signatures from Five-Move Identification Protocols.\\nYear: 2017\\n\\nAbstract: We carry out a concrete security analysis of signature schemes obtained from five-move identification protocols via the Fiat-Shamir transform. Concretely, we obtain tightly-secure signatures based on the computational Diffie-Hellman (CDH), the short-exponent CDH, and the Factoring (FAC) assumptions. All our signature schemes have tight reductions to search problems, which is in stark contrast to all known signature schemes obtained from the classical Fiat-Shamir transform (based on three-move identification protocols), which either have a non-tight reduction to a search problem, or a tight reduction to a (potentially) stronger decisional problem. Surprisingly, our CDH-based scheme turns out to be (a slight simplification of) the Chevallier-Mames signature scheme (CRYPTO 05), thereby providing a theoretical explanation of its tight security proof via five-move identification protocols.\",\n \"Title: On the One-Per-Message Unforgeability of (EC)DSA and Its Variants.\\nYear: 2017\\n\\nAbstract: The American signature standards DSA and ECDSA, as well as their Russian and Chinese counterparts GOST 34.10 and SM2, are of utmost importance in the current security landscape. The mentioned schemes are all rooted in the Elgamal signature scheme (1984) and use a hash function and a cyclic group as building blocks. Unfortunately, authoritative security guarantees for the schemes are still due: All existing positive results on their security use aggressive idealization approaches, like the generic group model, leading to debatable overall results.\",\n \"Title: CRYSTALS-Dilithium: A Lattice-Based Digital Signature Scheme.\\nYear: 2018\\n\\nAbstract: In this paper, we present the lattice-based signature scheme Dilithium, which is a component of the CRYSTALS (Cryptographic Suite for Algebraic Lattices) suite that was submitted to NIST’s call for post-quantum cryptographic standards. The design of the scheme avoids all uses of discrete Gaussian sampling and is easily implementable in constant-time. For the same security levels, our scheme has a public key that is 2.5X smaller than the previously most efficient lattice-based schemes that did not use Gaussians, while having essentially the same signature size. In addition to the new design, we significantly improve the running time of the main component of many lattice-based constructions – the number theoretic transform. Our AVX2-based implementation results in a speed-up of roughly a factor of 2 over the previously best algorithms that appear in the literature. The techniques for obtaining this speed-up also have applications to other lattice-based schemes.\",\n \"Title: An Algebraic Framework for Diffie–Hellman Assumptions\\nYear: 2013\\n\\nAbstract: We put forward a new algebraic framework to generalize and analyze Diffie---Hellman like decisional assumptions which allows us to argue about security and applications by considering only algebraic properties. Our $$\\\\\\\\mathcal {D}_{\\\\\\\\ell ,k}\\\\\\\\text{- }\\\\\\\\textsf {MDDH}$$Dℓ,k-MDDH Assumption states that it is hard to decide whether a vector in $$\\\\\\\\mathbb {G}^\\\\\\\\ell $$Gℓ is linearly dependent of the columns of some matrix in $$\\\\\\\\mathbb {G}^{\\\\\\\\ell \\\\\\\\times k}$$Gℓ×k sampled according to distribution $$\\\\\\\\mathcal {D}_{\\\\\\\\ell ,k}$$Dℓ,k. It covers known assumptions such as $$\\\\\\\\textsf {DDH},\\\\\\\\, 2\\\\\\\\text{- }\\\\\\\\textsf {Lin}$$DDH,2-Lin (Linear Assumption) and $$k\\\\\\\\text{- }\\\\\\\\textsf {Lin}$$k-Lin (the k-Linear Assumption). Using our algebraic viewpoint, we can relate the generic hardness of our assumptions in m-linear groups to the irreducibility of certain polynomials which describe the output of $$\\\\\\\\mathcal {D}_{\\\\\\\\ell ,k}$$Dℓ,k. We use the hardness results to find new distributions for which the $$\\\\\\\\mathcal {D}_{\\\\\\\\ell ,k}\\\\\\\\text{- }\\\\\\\\textsf {MDDH}$$Dℓ,k-MDDH Assumption holds generically in m-linear groups. In particular, our new assumptions $$2\\\\\\\\text{- }\\\\\\\\textsf {SCasc}$$2-SCasc and $$2\\\\\\\\text{- }\\\\\\\\textsf {ILin}$$2-ILin are generically hard in bilinear groups and, compared to $$2\\\\\\\\text{- }\\\\\\\\textsf {Lin}$$2-Lin, have shorter description size, which is a relevant parameter for efficiency in many applications. These results support using our new assumptions as natural replacements for the $$2\\\\\\\\text{- }\\\\\\\\textsf {Lin}$$2-Lin assumption which was already used in a large number of applications. To illustrate the conceptual advantages of our algebraic framework, we construct several fundamental primitives based on any $$\\\\\\\\textsf {MDDH}$$MDDH Assumption. In particular, we can give many instantiations of a primitive in a compact way, including public-key encryption, hash proof systems, pseudo-random functions, and Groth---Sahai NIZK and NIWI proofs. As an independent contribution, we give more efficient NIZK and NIWI proofs for membership in a subgroup of $$\\\\\\\\mathbb {G}^\\\\\\\\ell $$Gℓ. The results imply very significant efficiency improvements for a large number of schemes.\",\n \"Title: The Algebraic Group Model and its Applications.\\nYear: 2018\\n\\nAbstract: One of the most important and successful tools for assessing hardness assumptions in cryptography is the Generic Group Model (GGM). Over the past two decades, numerous assumptions and protocols have been analyzed within this model. While a proof in the GGM can certainly provide some measure of confidence in an assumption, its scope is rather limited since it does not capture group-specific algorithms that make use of the representation of the group. To overcome this limitation, we propose the Algebraic Group Model (AGM), a model that lies in between the Standard Model and the GGM. It is the first restricted model of computation covering group-specific algorithms yet allowing to derive simple and meaningful security statements. To prove its usefulness, we show that several important assumptions, among them the Computational Diffie-Hellman, the Strong Diffie-Hellman, and the interactive LRSW assumptions, are equivalent to the Discrete Logarithm (DLog) assumption in the AGM. On the more practical side, we prove tight security reductions for two important schemes in the AGM to DLog or a variant thereof: the BLS signature scheme and Groth's zero-knowledge SNARK (EUROCRYPT 2016), which is the most efficient SNARK for which only a proof in the GGM was known. Our proofs are quite simple and therefore less prone to subtle errors than those in the GGM. Moreover, in combination with known lower bounds on the Discrete Logarithm assumption in the GGM, our results can be used to derive lower bounds for all the above-mentioned results in the GGM.\",\n \"Title: Generic Authenticated Key Exchange in the Quantum Random Oracle Model.\\nYear: 2018\\n\\nAbstract: We propose \\\\\\\\(\\\\\\\\mathsf {FO_\\\\\\\\mathsf {AKE}}\\\\\\\\), a generic construction of two-message authenticated key exchange (AKE) from any passively secure public key encryption (PKE) in the quantum random oracle model (QROM). Whereas previous AKE constructions relied on a Diffie-Hellman key exchange or required the underlying PKE scheme to be perfectly correct, our transformation allows arbitrary PKE schemes with non-perfect correctness. Dealing with imperfect schemes is one of the major difficulties in a setting involving active attacks. Our direct construction, when applied to schemes such as the submissions to the recent NIST post-quantum competition, is more natural than previous AKE transformations. Furthermore, we avoid the use of (quantum-secure) digital signature schemes which are considerably less efficient than their PKE counterparts. As a consequence, we can instantiate our AKE transformation with any of the submissions to the recent NIST competition, e.g., ones based on codes and lattices.\",\n \"Title: Lossy Trapdoor Permutations with Improved Lossiness.\\nYear: 2019\\n\\nAbstract: Lossy trapdoor functions (Peikert and Waters, STOC 2008 and SIAM J. Computing 2011) imply, via black-box transformations, a number of interesting cryptographic primitives, including chosen-ciphertext secure public-key encryption. Kiltz, O’Neill, and Smith (CRYPTO 2010) showed that the RSA trapdoor permutation is lossy under the Phi-hiding assumption, but syntactically it is not a lossy trapdoor function since it acts on (mathbb {Z}_N) and not on strings. Using a domain extension technique by Freeman et al. (PKC 2010 and J. Cryptology 2013) it can be extended to a lossy trapdoor permutation, but with considerably reduced lossiness.\",\n \"Title: Tightly-Secure Authenticated Key Exchange.\\nYear: 2014\\n\\nAbstract: We construct the first Authenticated Key Exchange (AKE) protocol whose security does not degrade with an increasing number of users or sessions. We describe a three-message protocol and prove security in an enhanced version of the classical Bellare-Rogaway security model. Our construction ismodular, it can be instantiated efficiently from standard assumptions (such as the SXDH or DLIN assumptions in pairing-friendly groups). For instance, we provide an SXDH-based protocol with only 14 group elements and 4 exponents communication complexity (plus some bookkeeping information). Along the way we develop new, stronger security definitions for digital signatures and key encapsulation mechanisms. For instance, we introduce a security model for digital signatures that provides existential unforgeability under chosen-message attacks in a multi-user setting with adaptive corruptions of secret keys. We show how to construct efficient schemes that satisfy the new definitions with tight security proofs under standard assumptions.\",\n \"Title: A Modular Treatment of Blind Signatures from Identification Schemes.\\nYear: 2019\\n\\nAbstract: We propose a modular security treatment of blind signatures derived from linear identification schemes in the random oracle model. To this end, we present a general framework that captures several well known schemes from the literature and allows to prove their security. Our modular security reduction introduces a new security notion for identification schemes called One-More-Man In the Middle Security which we show equivalent to the classical One-More-Unforgeability notion for blind signatures. We also propose a generalized version of the Forking Lemma due to Bellare and Neven (CCS 2006) and show how it can be used to greatly improve the understandability of the classical security proofs for blind signatures schemes by Pointcheval and Stern (Journal of Cryptology 2000).\",\n \"Title: On the Security of Two-Round Multi-Signatures\\nYear: 2019\\n\\nAbstract: A multi-signature scheme allows a group of signers to collaboratively sign a message, creating a single signature that convinces a verifier that every individual signer approved the message. The increased interest in technologies to decentralize trust has triggered the proposal of highly efficient two-round Schnorr-based multi-signature schemes designed to scale up to thousands of signers, namely BCJ by Bagherzandi et al. (CCS 2008), MWLD by Ma et al. (DCC 2010), CoSi by Syta et al. (S&P 2016), and MuSig by Maxwell et al. (ePrint 2018). In this work, we point out serious security issues in all currently known two-round multi-signature schemes (without pairings). First, we prove that none of the schemes can be proved secure without radically departing from currently known techniques. Namely, we show that if the one-more discrete-logarithm problem is hard, then no algebraic reduction exists that proves any of these schemes secure under the discrete-logarithm or one-more discrete-logarithm problem. We point out subtle flaws in the published security proofs of the above schemes (except CoSi, which was not proved secure) to clarify the contradiction between our result and the existing proofs. Next, we describe practical sub-exponential attacks on all schemes, providing further evidence to their insecurity. Being left without two-round multi-signature schemes, we present mBCJ, a variant of the BCJ scheme that we prove secure under the discrete-logarithm assumption in the random-oracle model. Our experiments show that mBCJ barely affects scalability compared to CoSi, allowing 16384 signers to collaboratively sign a message in about 2 seconds, making it a highly practical and provably secure alternative for large-scale deployments.\",\n \"Title: On the Impossibility of Purely Algebraic Signatures\\nYear: 2021\\n\\nAbstract: The existence of one-way functions implies secure digital signatures, but not public-key encryption (at least in a black-box setting). Somewhat surprisingly, though, efficient public-key encryption schemes appear to be much easier to construct from concrete algebraic assumptions (such as the factoring of Diffie-Hellman-like assumptions) than efficient digital signature schemes. In this work, we provide one reason for this apparent difficulty to construct efficient signature schemes. Specifically, we prove that a wide range of algebraic signature schemes (in which verification essentially checks a number of linear equations over a group) fall to conceptually surprisingly simple linear algebra attacks. In fact, we prove that in an algebraic signature scheme, sufficiently many signatures can be linearly combined to a signature of a fresh message. We present attacks both in known-order and hidden-order groups (although in hidden-order settings, we have to restrict our definition of algebraic signatures a little). More explicitly, we show: - the insecurity of all algebraic signature schemes in Maurer's generic group model (in pairing-free groups), as long as these schemes do not rely on other cryptographic assumptions, such as hash functions. - the insecurity of a natural class of signatures in hidden-order groups, where verification consists of linear equations over group elements. We believe that this highlights the crucial role of public verifiability in digital signature schemes. Namely, while public-key encryption schemes do not require any publicly verifiable structure on ciphertexts, it is exactly this structure on signatures that invites attacks like ours and makes it hard to construct efficient signatures.\",\n \"Title: Faster Lattice-Based KEMs via a Generic Fujisaki-Okamoto Transform Using Prefix Hashing\\nYear: 2021\\n\\nAbstract: ABSTRACTConstructing an efficient CCA-secure KEM is generally done by first constructing a passively-secure PKE scheme, and then applying the Fujisaki-Okamoto (FO) transformation. The original FO transformation was designed to offer security in a single user setting. A stronger notion, known as multi-user security, considers the attacker's advantage in breaking one of many user's ciphertexts. Bellare et al. (EUROCRYPT 2000) showed that standard single user security implies multi-user security with a multiplicative tightness gap equivalent to the number of users. To obtain even more confidence in the security of KEMs in the multi-user setting, it is a common design paradigm to also \\\"domain separate'' the random oracles of each user by including his public key as an input to the hash function. We are not aware of any formal analysis of this technique, but it was at least informally thought to be a computationally cheap way to add security. This design principle was carried over into the FO transformations used by several schemes in the NIST post-quantum standardization effort -- notably the lattice-based schemes Kyber and Saber, which are two of the four KEM finalists. In this work, we formally analyze domain separation in the context of the FO transformation in the multi-user setting. We first show that including the public key in the hash function is indeed important for the tightness of the security reductions in the ROM and the QROM. At the same time, we show that including the entire public key into the hash function is unnecessarily wasteful -- it is enough to include just a small (e.g. $32$ byte) unpredictable part of the key to achieve the same security. Reducing the input of the hash function results in a very noticeable improvement in the running time of the lattice-based KEMs. In particular, using this generic transform results in a 2X - 3X speed-up over the current (Round 3) key generation and encapsulation procedures in Kyber, and up to a 40% improvement in the same functions in Saber.\",\n \"Title: Authenticated Key Exchange And Signatures With Tight Security In The Standard Model\\nYear: 2021\\n\\nAbstract: We construct the first authenticated key exchange protocols that achieve tight security in the standard model. Previous works either relied on techniques that seem to inherently require a random oracle, or achieved only \\\"Multi-Bit-Guess\\\" security, which is not known to compose tightly, for instance, to build a secure channel.Our constructions are generic, based on digital signatures and key encapsulation mechanisms (KEMs). The main technical challenges we resolve is to determine suitable KEM security notions which on the one hand are strong enough to yield tight security, but at the same time weak enough to be efficiently instantiable in the standard model, based on standard techniques such as universal hash proof systems.Digital signature schemes with tight multi-user security in presence of adaptive corruptions are a central building block, which is used in all known constructions of tightly-secure AKE with full forward security. We identify a subtle gap in the security proof of the only previously known efficient standard model scheme by Bader et al. (TCC 2015). We develop a new variant, which yields the currently most efficient signature scheme that achieves this strong security notion without random oracles and based on standard hardness assumptions.\",\n \"Title: Chosen Ciphertext Security With Optimal Ciphertext Overhead\\nYear: 2010\\n\\nAbstract: Every public-key encryption scheme has to incorporate a certain amount of randomness into its ciphertexts to provide semantic security against chosen ciphertext attacks (IND-CCA). The difference between the length of a ciphertext and the embedded message is called the ciphertext overhead. While a generic brute-force adversary running in 2(t) steps gives a theoretical lower bound of t bits on the ciphertext overhead for IND-CPA security, the best known IND-CCA secure schemes demand roughly 2t bits even in the random oracle model. Is the t-bit gap essential for achieving IND-CCA security? We close the gap by proposing an IND-CCA secure scheme whose ciphertext overhead matches the generic lower bound up to a small constant. Our scheme uses a variation of a four-round Feistel network in the random oracle model and hence belongs to the family of OAEP-based schemes. Maybe of independent interest is a new efficient method to encrypt long messages exceeding the length of the permutation while retaining the minimal overhead.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":72,"string":"72"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":263,"string":"263"}}},{"rowIdx":264,"cells":{"question_id":{"kind":"string","value":"David Hsu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Formalizing Human-Robot Mutual Adaptation: A Bounded Memory Model.\" using the following items: 1. Mutual adaptation\n2. Human-robot collaboration\n3. Bounded-memory adaptation model (BAM)\n4. Partially observable stochastic model\n5. Improved effectiveness of human-robot teams"},"answer":{"kind":"string","value":"Mutual adaptation is critical for effective team collaboration. This paper presents a formalism for human-robot mutual adaptation in collaborative tasks. We propose the bounded-memory adaptation model (BAM), which captures human adaptive behaviours based on a bounded memory assumption. We integrate BAM into a partially observable stochastic model, which enables robot adaptation to the human. When the human is adaptive, the robot will guide the human towards a new, optimal collaborative strategy unknown to the human in advance. When the human is not willing to change their strategy, the robot adapts to the human in order to retain human trust. Human subject experiments indicate that the proposed formalism can significantly improve the effectiveness of human-robot teams, while human subject ratings on the robot performance and trust are comparable to those achieved by cross training, a state-of-the-art human-robot team training practice."},"correct_answer":{"kind":"string","value":"Mutual adaptation is critical for effective team collaboration. This paper presents a formalism for human-robot mutual adaptation in collaborative tasks. We propose the bounded-memory adaptation model (BAM), which captures human adaptive behaviours based on a bounded memory assumption. We integrate BAM into a partially observable stochastic model, which enables robot adaptation to the human. When the human is adaptive, the robot will guide the human towards a new, optimal collaborative strategy unknown to the human in advance. When the human is not willing to change their strategy, the robot adapts to the human in order to retain human trust. Human subject experiments indicate that the proposed formalism can significantly improve the effectiveness of human-robot teams, while human subject ratings on the robot performance and trust are comparable to those achieved by cross training, a state-of-the-art human-robot team training practice."},"documents":{"kind":"list like","value":["Title: A point-based POMDP planner for target tracking\nYear: 2008\n\nAbstract: Abstract—Target,tracking,has two,variants,that are often studied independently,with different approaches: target search- ing requires a robot to find a target initially not visible, and,target following,requires,a robot,to maintain,visibility on a target initially visible. In this work, we use a partially observable,Markov,decision process (POMDP) to build a single model,that unifies target searching,and,target following. The POMDP solution exhibits interesting tracking behaviors, such as anticipatory moves that exploit target dynamics, information- gathering moves that reduce target position uncertainty, and energy-conserving actions that allow the target to get out of sight, but do not compromise long-term tracking performance. To overcome,the high,computational,complexity,of solving POMDPs, we have developed SARSOP, a new point-based POMDP algorithm,based,on successively approximating,the space reachable,under,optimal,policies. Experimental,results show that SARSOP is competitive with the fastest existing point- based algorithm,on many,standard,test problems,and,faster by many,times on some.","Title: Component-based construction of bio-pathway models: The parameter estimation problem\nYear: 2011\n\nAbstract: Constructing and analyzing large biological pathway models is a significant challenge. We propose a general approach that exploits the structure of a pathway to identify pathway components, constructs the component models, and finally assembles the component models into a global pathway model. Specifically, we apply this approach to pathway parameter estimation, a main step in pathway model construction. A large biological pathway often involves many unknown parameters and the resulting high-dimensional search space poses a major computational difficulty. By exploiting the structure of a pathway and the distribution of available experimental data over the pathway, we decompose a pathway into components and perform parameter estimation for each component. However, some parameters may belong to multiple components. Independent parameter estimates from different components may be in conflict for such parameters. To reconcile these conflicts, we represent each component as a factor graph, a standard probabilistic graphical model. We then combine the resulting factor graphs and use a probabilistic inference technique called belief propagation to obtain the maximally likely parameter values that are globally consistent. We validate our approach on a synthetic pathway model based on the Akt-MAPK signaling pathways. The results indicate that the approach can potentially scale up to large pathway models.","Title: Computing the largest inscribed isothetic rectangle\nYear: 1995\n\nAbstract: This paper describes an algorithm to compute, in Theta(log n) time, a rectangle that is contained in a convex n-gon, has sides parallel to the coordinate axes, and has maximum area. With a slight modification it will compute the smallest perimeter. The algorithm uses a tentative prune-and-search approach, even though this problem does not appear to fit into the functional framework of Kirkpatrick and Snoeyink.","Title: Field-Programmable Learning Arrays\nYear: 2002\n\nAbstract: This paper introduces the Field-Programmable Learning Array, a new paradigm for rapid prototyping of learning primitives and machine- learning algorithms in silicon. The FPLA is a mixed-signal counterpart to the all-digital Field-Programmable Gate Array in that it enables rapid prototyping of algorithms in hardware. Unlike the FPGA, the FPLA is targeted directly for machine learning by providing local, parallel, on- line analog learning using floating-gate MOS synapse transistors. We present a prototype FPLA chip comprising an array of reconfigurable computational blocks and local interconnect. We demonstrate the via- bility of this architecture by mapping several learning circuits onto the prototype chip.","Title: Monte Carlo Value Iteration for Continuous-State POMDPs.\nYear: 2010\n\nAbstract: Partially observable Markov decision processes (POMDPs) have been successfully applied to various robot motion planning tasks under uncertainty. However, most existing POMDP algorithms assume a discrete state space, while the natural state space of a robot is often continuous. This paper presents Monte Carlo Value Iteration (MCVI) for continuous-state POMDPs. MCVI samples both a robot's state space and the corresponding belief space, and avoids inefficient a priori discretization of the state space as a grid. Both theoretical results and preliminary experimental results indicate that MCVI is a promising new approach for robot motion planning under uncertainty.","Title: Planning how to learn\nYear: 2013\n\nAbstract: When a robot uses an imperfect system model to plan its actions, a key challenge is the exploration-exploitation trade-off between two sometimes conflicting objectives: (i) learning and improving the model, and (ii) immediate progress towards the goal, according to the current model. To address model uncertainty systematically, we propose to use Bayesian reinforcement learning and cast it as a partially observable Markov decision process (POMDP). We present a simple algorithm for offline POMDP planning in the continuous state space. Offline planning produces a POMDP policy, which can be executed efficiently online as a finite-state controller. This approach seamlessly integrates planning and learning: it incorporates learning objectives in the computed plan, which then enables the robot to learn nearly optimally online and reach the goal. We evaluated the approach in simulations on two distinct tasks, acrobot swing-up and autonomous vehicle navigation amidst pedestrians, and obtained interesting preliminary results.","Title: A mixed-signal approach to high-performance low-power linear filters\nYear: 2001\n\nAbstract: We present a new approach to the design of high-performance low-power linear filters. We use p-channel synapse transistors as analog memory cells, and mixed-signal circuits for fast low-power arithmetic. To demonstrate the effectiveness of our approach, we have built a 16-tap 7-b 200-MHz mixed-signal finite-impulse response (FIR) filter that consumes 3 mW at 3.3 V. The filter uses synapse pFETs to...","Title: Motion Planning for 3-D Target Tracking among Obstacles\nYear: 2007\n\nAbstract: The goal of target tracking is to compute motion strategies for a robot equipped with visual sensors, so that it can effectively track a moving target despite obstruction by obstacles. It is an important problem with many applications in robotics. Existing work focuses mostly on the 2-D version of the problem, partly due to the complexity of dealing with 3-D visibility relationships. This paper proposes an online algorithm for 3-D target tracking among obstacles, using only local geometric information available to a robot's visual sensors. Key to this new algorithm is the definition and efficient computation of a risk function, which tries to capture a target's ability in escaping from the robot sensors' visibility region in both short and long terms. The robot then moves to minimize this risk function locally in a greedy fashion. In the absence of occlusion by obstacles, the standard tracking algorithm based on visual servo control can be considered a special case of our algorithm. Experiments show that the new algorithm generated interesting tracking behaviors in three dimensions and performed substantially better than visual servo control in simulation.","Title: Motion Strategies for People Tracking in Cluttered and Dynamic Environments\nYear: 2008\n\nAbstract: The key contribution of this work is the construction of a robot tracking system that follows an unpredictable target (e.g people) in cluttered, unknown and dynamic environments. To do so, mobility constraints, sensor limitations, and uncertainty have been addressed at both the algorithmic and implementation levels. The work formulates target tracking as minimizing an objective function that models the risk of the target's escape and derives this risk function from basic principles. Various practical hardware limitations - e.g., sensor's field of view, safe navigation are taken into account either as part of the risk function or as constraints during risk minimization. The resulting tracker demonstrates substantially improved performance, compared with other local online strategies. The tracker was able to track a person walking around in indoor office environments as well as in a highly dynamic and public environment, like the school cafeteria successfully.","Title: A decompositional approach to parameter estimation in pathway modeling: a case study of the Akt and MAPK pathways and their crosstalk.\nYear: 2006\n\nAbstract: Parameter estimation is a critical problem in modeling biological pathways. It is difficult because of the large number of parameters to be estimated and the limited experimental data available. In this paper, we propose a decompositional approach to parameter estimation. It exploits the structure of a large pathway model to break it into smaller components, whose parameters can then be estimated independently. This leads to significant improvements in computational efficiency. We present our approach in the context of Hybrid Functional Petri Net modeling and evolutionary search for parameter value estimation. However, the approach can be easily extended to other modeling frameworks and is independent of the search method used. We have tested our approach on a detailed model of the Akt and MAPK pathways with two known and one hypothesized crosstalk mechanisms. The entire model contains 84 unknown parameters. Our simulation results exhibit good correlation with experimental data, and they yield positive evidence in support of the hypothesized crosstalk between the two pathways.","Title: Using robotics to fold proteins and dock ligands.\nYear: 2002\n\nAbstract: The problems of protein folding and ligand docking have been explored largely using molecular dynamics or Monte Carlo methods. These methods are very compute intensive because they often explore a much wider range of energies, conformations and time than necessary. In addition, Monte Carlo methods often get trapped in local minima. We initially showed that robotic motion planning permitted one to determine the energy of binding and dissociation of ligands from protein binding sites (Singh et al., 1999). The robotic motion planning method maps complicated three-dimensional conformational states into a much simpler, but higher dimensional space in which conformational rearrangements can be represented as linear paths. The dimensionality of the conformation space is of the same order as the number of degrees of conformational freedom in three-dimensional space. We were able to determine the relative energy of association and dissociation of a ligand to a protein by calculating the energetics of interaction for a few thousand conformational states in the vicinity of the protein and choosing the best path from the roadmap. More recently, we have applied roadmap planning to the problem of protein folding (Apaydin et al., 2002a). We represented multiple conformations of a protein as nodes in a compact graph with the edges representing the probability of moving between neighboring states. Instead of using Monte Carlo simulation to simulate thousands of possible paths through various conformational states, we were able to use Markov methods to calculate the steady state occupancy of each conformation, needing to calculate the energy of each conformation only once. We referred to this Markov method of representing multiple conformations and transitions as stochastic roadmap simulation or SRS. We demonstrated that the distribution of conformational states calculated with exhaustive Monte Carlo simulations asymptotically approached the Markov steady state if the same Boltzman energy distribution was used in both methods. SRS permits one to calculate contributions from all possible paths simultaneously with far fewer energy calculations than Monte Carlo or molecular dynamics methods. The SRS method also permits one to represent multiple unfolded starting states and multiple, near-native, folded states and all possible paths between them simultaneously. The SRS method is also independent of the function used to calculate the energy of the various conformational states. In a paper to be presented at this conference (Apaydin et al., 2002b) we have also applied SRS to ligand docking in which we calculate the dynamics of ligand-protein association and dissociation in the region of various binding sites on a number of proteins. SRS permits us to determine the relative times of association to and dissociation from various catalytic and non-catalytic binding sites on protein surfaces. Instead of just following the best path in a roadmap, we can calculate the contribution of all the possible binding or dissociation paths and their relative probabilities and energies simultaneously.","Title: A piece-wise harmonic Langevin model of EEG dynamics: Theory and application to EEG seizure detection\nYear: 2005\n\nAbstract: Electroencephalogram (EEG) dynamics results from the motion of charged particles in the brain. By invoking the laws of classical physics, we show that EEG dynamics obeys, at short enough times, a piece-wise quadratic Langevin equation characterized by an effective mass matrix, a piece-wise quadratic potential energy surface, a friction and random force matrix. In analyzing a sample seizure, we find with seizure onset a marked increase in the frequency of encounters with inflection points on the potential energy surface.","Title: Self-Calibrating Camera Projector Systems for Interactive Displays and Presentations\nYear: 2001\n\nAbstract: IntroductionWe demonstrate a self-calibrating system that employs uncalibratedcameras and microportable projectors to createnovel interactive displays and presentations.1Three benefitsof our system are detailed in the following sections.2. Automatic Keystone CorrectionThe image generated by an off-center projector appearsdistorted (Figure 1, left). Using an uncalibrated camerapointed at the presentation screen, our system automaticallyrecovers the projector-to-screen homography...","Title: SARSOP: Efficient Point-Based POMDP Planning by Approximating Optimally Reachable Belief Spaces\nYear: 2008\n\nAbstract: IN Proc. Robotics: Science & Systems, 2008 Abstract—Motion planning in uncertain and dynamic environ- ments is an essential capability for autonomous robots. Partially observable Markov decision processes (POMDPs) provide a principled mathematical framework for solving such problems, but they are often avoided in robotics due to high computational complexity. Our goal is to create practical POMDP algorithms and software for common robotic tasks. To this end, we have developed a new point-based POMDP algorithm that exploits the notion of optimally reachable belief spaces to improve com- putational efficiency. In simulation, we successfully applied the algorithm to a set of common robotic tasks, including instances of coastal navigation, grasping, mobile robot exploration, and target tracking, all modeled as POMDPs with a large number of states. In most of the instances studied, our algorithm substantially outperformed one of the fastest existing point-based algorithms. A software package implementing our algorithm will soon be released at http://motion.comp.nus.edu.sg/ projects/pomdp/pomdp.html.","Title: H-Walk: hierarchical distance computation for moving convex bodies\nYear: 1999\n\nAbstract: This paper presents the Hierarchical Walk, or H-Walk al- gorithm, which maintains the distance between two moving convex bodies by exploiting both motion coherence and hi- erarchical representations. For convex polygons, we prove that H-Walk improves on the classic Lin-Canny and Dobkin- Kirkpatrick algorithms. We have implemented H-Walk for moving convex polyhedra in three dimensions. Experimen- tal results indicate that, unlike previous incremental dis- tance computation algorithms, H-Walk adapts well to vari- able coherence in the motion.","Title: Workspace Importance Sampling for Probabilistic Roadmap Planning\nYear: 2004\n\nAbstract: Probabilistic Roadmap (PRM) planners have been successful in path planning of robots with many degrees of freedom, but they behave poorly when a robot's configu- ration space contains narrow passages. This paper presents workspace importance sampling (WIS), a new sampling strat- egy for PRM planning. Our main idea is to use geometric information from a robot's workspace as \"importance\" values to guide sampling in the corresponding configuration space. By doing so, WIS increases the sampling density in narrow passages and decreases the sampling density in wide-open regions. We tested the new planner on rigid-body and articulated robots in 2-D and 3-D environments. Experimental results show that WIS improves the planner's performance for path planning problems with narrow passages.","Title: Predicting experimental quantities in protein folding kinetics using stochastic roadmap simulation\nYear: 2006\n\nAbstract: This paper presents a new method for studying protein folding kinetics. It uses the recently introduced Stochastic Roadmap Simulation (SRS) method to estimate the transition state ensemble (TSE) and predict the rates and Φ-values for protein folding. The new method was tested on 16 proteins. Comparison with experimental data shows that it estimates the TSE much more accurately than an existing method based on dynamic programming. This leads to better folding-rate predictions. The results on Φ-value predictions are mixed, possibly due to the simple energy model used in the tests. This is the first time that results obtained from SRS have been compared against a substantial amount of experimental data. The success further validates the SRS method and indicates its potential as a general tool for studying protein folding kinetics.","Title: Stochastic roadmap simulation: an efficient representation and algorithm for analyzing molecular motion\nYear: 2002\n\nAbstract: Classic molecular motion simulation techniques, such as Monte Carlo (MC) simulation, generate motion pathways one at a time and spend most of their time in the local minima of the energy landscape defined over a molecular conformation space. Their high computational cost prevents them from being used to compute ensemble properties (properties requiring the analysis of many pathways). This paper introduces stochastic roadmap simulation (SRS) as a new computational approach for exploring the kinetics of molecular motion by simultaneously examining multiple pathways. These pathways are compactly encoded in a graph, which is constructed by sampling a molecular conformation space at random. This computation, which does not trace any particular pathway explicitly, circumvents the local-minima problem. Each edge in the graph represents a potential transition of the molecule and is associated with a probability indicating the likelihood of this transition. By viewing the graph as a Markov chain, ensemble properties can be efficiently computed over the entire molecular energy landscape. Furthermore, SRS converges to the same distribution as MC simulation. SRS is applied to two biological problems: computing the probability of folding, an important order parameter that measures the \"kinetic distance\" of a protein's conformation from its native state; and estimating the expected time to escape from a ligand-protein binding site. Comparison with MC simulations on protein folding shows that SRS produces arguably more accurate results, while reducing computation time by several orders of magnitude. Computational studies on ligand-protein binding also demonstrate SRS as a promising approach to study ligand-protein interactions.","Title: Adaptive Quantization and Density Estimation in Silicon\nYear: 2002\n\nAbstract: We present the bump mixture model, a statistical model for analog data where the probabilistic semantics, inference, and learning rules derive from low-level transistor behavior. The bump mixture model relies on translinear circuits to perform probabilistic infer- ence, and floating-gate devices to perform adaptation. This system is low power, asynchronous, and fully parallel, and supports vari- ous on-chip learning algorithms. In addition, the mixture model can perform several tasks such as probability estimation, vector quanti- zation, classification, and clustering. We tested a fabricated system on clustering, quantization, and classification of handwritten digits and show performance comparable to the E-M algorithm on mix- tures of Gaussians.","Title: Integrated perception and planning in the continuous space: A POMDP approach\nYear: 2013\n\nAbstract: The partially observable Markov decision process (POMDP) provides a principled mathematical model for integrating perception and planning, a major challenge in robotics. While there are efficient algorithms for moderately large discrete POMDPs, continuous models are often more natural for robotic tasks, and currently there are no practical algorithms that handle continuous POMDPs at an interesting scale. This paper presents an algorithm for continuous-state, continuous-observation POMDPs. We provide experimental results demonstrating its potential in robot planning and learning under uncertainty and a theoretical analysis of its performance. A direct benefit of the algorithm is to simplify model construction.","Title: Probabilistic Approximations of Signaling Pathway Dynamics\nYear: 2009\n\nAbstract: Systems of ordinary differential equations (ODEs) are often used to model the dynamics of complex biological pathways. We construct a discrete state model as a probabilistic approximation of the ODE dynamics by discretizing the value space and the time domain. We then sample a representative set of trajectories and exploit the discretization and the structure of the signaling pathway to encode these trajectories compactly as a dynamic Bayesian network. As a result, many interesting pathway properties can be analyzed efficiently through standard Bayesian inference techniques. We have tested our method on a model of EGF-NGF signaling pathway [1] and the results are very promising in terms of both accuracy and efficiency.","Title: A Fast Filter for Obstructed Nearest Neighbor Queries\nYear: 2004\n\nAbstract: In this paper, we study the Obstructed Nearest Neighbor (ONN) problem: given a set of points and a set of polygonal obstacles in two dimensions, find the k nearest neighbors to a query point according to the length of the shortest obstacle-avoiding path between two points. ONN query is useful both as a stand-alone tool in geographical information systems and as a primitive for spatial data analysis such as clustering and classification in the presence of obstacles. We propose an efficient ONN algorithm that processes only the data points and obstacles relevant to the query in an incremental way and thus filters out a large number of points and obstacles. Experiments on spatial data sets show the algorithm scales well with respect to the input data size and the number of nearest neighbors requested.","Title: Stochastic Conformational Roadmaps for Computing Ensemble Properties of Molecular Motion.\nYear: 2002\n\nAbstract: A key intuition behind probabilistic roadmap planners for motion planning is that many collision-free paths potentially exist between two given robot configurations. Hence the connectivity of a robot's free space can be captured effectively by a network of randomly sampled configurations. In this paper, a similar intuition is exploited to preprocess molecular motion pathways and efficiently compute their ensemble properties, i.e., properties characterizing the average behavior of many pathways. We construct a directed graph, called stochastic conformational roadmap, whose nodes are randomly sampled molecule conformations. A roadmap compactly encodes many molecular motion pathways. Ensemble properties are computed by viewing the roadmap as a Markov chain. A salient feature of this new approach is that it examines all the paths in the roadmap simultaneously, rather than one at a time as classic methods such as Monte Carlo (MC) simulation would do. It also avoids the local-minima problem encountered by the classic methods. Tests of the approach on two important biological problems show that it produces more accurate results and achieves several orders of magnitude reduction in computation time, compared with MC simulation.","Title: Composing Globally Consistent Pathway Parameter Estimates Through Belief Propagation\nYear: 2007\n\nAbstract: Parameter estimation of large bio-pathway models is an important and difficult problem. To reduce the prohibitive computational cost, one approach is to decompose a large model into components and estimate their parameters separately. However, the decomposed components often share common parts that may have conflicting parameter estimates, as they are computed independently within each component. In this paper, we propose to use a probabilistic inference technique called belief propagation to reconcile these independent estimates in a principled manner and compute new estimates that are globally consistent and fit well with data. An important advantage of our approach in practice is that it naturally handles incomplete or noisy data. Preliminary results based on synthetic data show promising performance in terms of both accuracy and efficiency.","Title: Disconnection Proofs For Motion Planning\nYear: 2001\n\nAbstract: Probabilistic road-map (PRM) planners have shown great promise in attacking previously infeasible motion planning problems with many degrees of freedom. Yet when such a planner Jails to find a path, it is not clear that no path exists, or that the planner simply did not sample adequately or intelligently the free part of the configuration space. We propose to attack the motion planning problem front the other end, focusing on disconnection proofs, or proofs showing that there exists no solution to the posed motion planning problem. Just as PRM planners avoid generating a complete description of the configuration space, our disconnection provers search for certain special classes of proofs that are compact and easy to find when the motion planning problem is 'obviously impossible,' avoiding complex geometric and combinatorial calculations. We demonstrate such a prover in action for a simple, ' yet still realistic, motion planning problem. When it fails. the prover suggests key milestones, or configurations of the robot that can then be passed on and used by a PRM planner Thus by hitting the motion planning problem from both ends, we hope to resolve the existence of a path, except in truly delicate border-line situations.","Title: Probabilistic approximations of ODEs based bio-pathway dynamics\nYear: 2011\n\nAbstract: Bio-chemical networks are often modeled as systems of ordinary differential equations (ODEs). Such systems will not admit closed form solutions and hence numerical simulations will have to be used to perform analyses. However, the number of simulations required to carry out tasks such as parameter estimation can become very large. To get around this, we propose a discrete probabilistic approximation of the ODEs dynamics. We do so by discretizing the value and the time domain and assuming a distribution of initial states w.r.t. the discretization. Then we sample a representative set of initial states according to the assumed initial distribution and generate a corresponding set of trajectories through numerical simulations. Finally, using the structure of the signaling pathway we encode these trajectories compactly as a dynamic Bayesian network. This approximation of the signaling pathway dynamics has several advantages. First, the discretized nature of the approximation helps to bridge the gap between the accuracy of the results obtained by ODE simulation and the limited precision of experimental data used for model construction and verification. Second and more importantly, many interesting pathway properties can be analyzed efficiently through standard Bayesian inference techniques instead of resorting to a large number of ODE simulations. We have tested our method on ODE models of the EGF-NGF signaling pathway [1] and the segmentation clock pathway [2]. The results are very promising in terms of accuracy and efficiency.","Title: CAPIR: Collaborative Action Planning with Intention Recognition\nYear: 2011\n\nAbstract: We apply decision theoretic techniques to construct non-player characters that are able to assist a human player in collaborative games. The method is based on solving Markov decision processes, which can be difficult when the game state is described by many variables. To scale to more complex games, the method allows decomposition of a game task into subtasks, each of which can be modelled by a Markov decision process. Intention recognition is used to infer the subtask that the human is currently performing, allowing the helper to assist the human in performing the correct task. Experiments show that the method can be effective, giving near-human level performance in helping a human in a collaborative game.","Title: On the Probabilistic Foundations of Probabilistic Roadmap Planning\nYear: 2006\n\nAbstract: Why is probabilistic roadmap (PRM) planning probabilistic? How does the probability measure used for sampling a robot's configuration space affect the performance of a PRM planner? These questions have received little attention so far. This paper tries to fill this gap, with the intent to identify promising directions to improve future planners. It introduces the probabilistic foundations of PRM planning and examines previous work in this context. It shows that the success of PRM planning depends mainly and critically on favorable \"visibility\" properties of a robot's configuration space. A promising direction for speeding up PRM planners is to infer partial knowledge on such properties from both workspace geometry and information gathered during roadmap construction, and to use this knowledge to adapt the probability measure for sampling. This paper also shows that the choice of the sampling source, pseudo-random or deterministic, has small impact on a PRM planner's performance, compared to that of the sampling measure. These conclusions are supported by both theoretical and empirical results.","Title: Capturing the Connectivity of High-Dimensional Geometric Spaces by Parallelizable Random Sampling Techniques\nYear: 1998\n\nAbstract: Finding paths in high-dimensional gemetric spaces is a provably hard problem. Recently, a general randomized planning scheme has emerged as an effective approach to solve this problem. In this scheme the planner samples the space at random and build a network of simple paths, called a probabilistic roadmap. This paper describes a basic probabilistic roadmap planner, which is easily parallelizable, and provides a formal analysis that explains its empirical success when the space satisfies two geometric properties called epsilon-goodness and expansiveness.","Title: Incremental signaling pathway modeling by data integration\nYear: 2010\n\nAbstract: Constructing quantitative dynamic models of signaling pathways is an important task for computational systems biology Pathway model construction is often an inherently incremental process, with new pathway players and interactions continuously being discovered and additional experimental data being generated Here we focus on the problem of performing model parameter estimation incrementally by integrating new experimental data into an existing model A probabilistic graphical model known as the factor graph is used to represent pathway parameter estimates By exploiting the network structure of a pathway, a factor graph compactly encodes many parameter estimates of varying quality as a probability distribution When new data arrives, the parameter estimates are refined efficiently by applying a probabilistic inference algorithm known as belief propagation to the factor graph A key advantage of our approach is that the factor graph model contains enough information about the old data, and uses only new data to refine the parameter estimates without requiring explicit access to the old data To test this approach, we applied it to the Akt-MAPK pathways, which regulate the apoptotic process and are among the most actively studied signaling pathways The results show that our new approach can obtain parameter estimates that fit the data well and refine them incrementally when new data arrives.","Title: pFlexAna: detecting conformational changes in remotely related proteins.\nYear: 2008\n\nAbstract: The pFlexAna (protein flexibility analyzer) web server detects and displays conformational changes in remotely related proteins, without relying on sequence homology. To do so, it first applies a reliable statistical test to align core protein fragments that are structurally similar and then clusters these aligned fragment pairs into super-alignments, according to the similarity of geometric transformations that align them. The result is that the dominant conformational changes occur between the clusters, while the smaller conformational changes occur within a cluster. pFlexAna is available at http://bigbird.comp.nus.edu.sg/pfa2/.","Title: Multi-Level Free-Space Dilation For Sampling Narrow Passages In Prm Planning\nYear: 2006\n\nAbstract: Free-space dilation is an effective approach for narrow passage sampling, a well-recognized difficulty in probabilistic roadmap (PRM) planning. Key to this approach are methods for dilating the free space and for determining the amount of dilation needed. This paper presents a new method of dilation by shrinking the geometric models of robots and obstacles. Compared with existing work, the new method is more efficient in both running time and memory usage. It is also integrated with collision checking, a key operation in PRM planning. The efficiency of the dilation method enables a new PRM planner which quickly constructs a series of dilated free spaces and automatically determine the amount of dilation needed. Experiments show that both the dilation method and the planner work well in complex geometric environments. In particular, the planner reliably solved the most difficult version of the alpha puzzle, a benchmark test for PRM planners.","Title: The creation of a music-driven digital violinist\nYear: 2004\n\nAbstract: This paper describes an initial attempt on a music-driven digital violinist (MDV) system, which automatically generates animation of a violinist based on violin music. MDV first analyzes the input audio signal and transcribes it into music notes. Next it uses the notes to synthesize the animated video of a violinist. Tests on the prototype system show that it achieves adequate visual realism and near real-time performance.","Title: Monte Carlo Bayesian Reinforcement Learning.\nYear: 2012\n\nAbstract: Bayesian reinforcement learning (BRL) encodes prior knowledge of the world in a model and represents uncertainty in model parameters by maintaining a probability distribution over them. This paper presents Monte Carlo BRL (MC-BRL), a simple and general approach to BRL. MC-BRL samples a priori a finite set of hypotheses for the model parameter values and forms a discrete partially observable Markov decision process (POMDP) whose state space is a cross product of the state space for the reinforcement learning task and the sampled model parameter space. The POMDP does not require conjugate distributions for belief representation, as earlier works do, and can be solved relatively easily with point-based approximation algorithms. MC-BRL naturally handles both fully and partially observable worlds. Theoretical and experimental results show that the discrete POMDP approximates the underlying BRL task well with guaranteed performance.","Title: Covering Number for Efficient Heuristic-based POMDP Planning.\nYear: 2014\n\nAbstract: The difficulty of POMDP planning depends on the size of the search space involved. Heuristics are often used to reduce the search space size and improve computational efficiency; however, there are few theoretical bounds on their effectiveness. In this paper, we use the covering number to characterize the size of the search space reachable under heuristics and connect the complexity of POMDP planning to the effectiveness of heuristics. With insights from the theoretical analysis, we have developed a practical POMDP algorithm, Packing-Guided Value Iteration (PGVI). Empirically, PGVI is competitive with the state-of-the-art point-based POMDP algorithms on 65 small benchmark problems and outperforms them on 4 larger problems.","Title: Neuronal avalanches and criticality: A dynamical model for homeostasis\nYear: 2006\n\nAbstract: The dynamics of microelectrode local field potentials from cortical slice cultures shows critical behavior. A desirable feature of criticality is that information transmission is optimal in this state. We explore a biologically plausible neural net model that can dynamically converge on criticality and that can return to criticality if perturbed away from it. Our model assumes the presence of a preferred target firing rate, with dynamical adjustments of internodal connection strengths to approach this firing rate. We suggest that mechanisms for maintaining firing rate homeostasis may also maintain a neural system at criticality.","Title: Bounded Uncertainty Roadmaps for Path Planning\nYear: 2008\n\nAbstract: Motion planning under uncertainty is an important problem in robotics. Although probabilistic sampling is highly successful for motion planning of robots with many degrees of freedom, sampling-based algorithms typically ignore uncertainty during planning. We in- troduce the notion of a bounded uncertainty roadmap (BURM) and use it to extend sampling- based algorithms for planning under uncertainty in environment maps. The key idea of our approach is to evaluate uncertainty, represented by collision probability bounds, at multiple resolutions in different regions of the configuration space, depending on their relevance for finding a best path. Preliminary experimental results show that our approach is highly effec- tive: our BURM algorithm is at least 40 times faster than an algorithm that tries to evaluate collision probabilities exactly, and it is not much slower than classic probabilistic roadmap planning algorithms, which ignore uncertainty in environment maps.","Title: Planning under Uncertainty for Robotic Tasks with Mixed Observability\nYear: 2010\n\nAbstract: Partially observable Markov decision processes (POMDPs) provide a principled, general framework for robot motion planning in uncertain and dynamic environments. They have been applied to various robotic tasks. However, solving POMDPs exactly is computationally intractable. A major challenge is to scale up POMDP algorithms for complex robotic tasks. Robotic systems often have mixed observability : even when a robotâ聙聶s state is not fully observable, some components of the state may still be so. We use a factored model to represent separately the fully and partially observable components of a robotâ聙聶s state and derive a compact lower-dimensional representation of its belief space. This factored representation can be combined with any point-based algorithm to compute approximate POMDP solutions. Experimental results show that on standard test problems, our approach improves the performance of a leading point-based POMDP algorithm by many times.","Title: A Computational And Experimental Study Of The Regulatory Mechanisms Of The Complement System\nYear: 2011\n\nAbstract: The complement system is key to innate immunity and its activation is necessary for the clearance of bacteria and apoptotic cells. However, insufficient or excessive complement activation will lead to immune-related diseases. It is so far unknown how the complement activity is up- or down-regulated and what the associated pathophysiological mechanisms are. To quantitatively understand the modulatory mechanisms of the complement system, we built a computational model involving the enhancement and suppression mechanisms that regulate complement activity. Our model consists of a large system of Ordinary Differential Equations (ODEs) accompanied by a dynamic Bayesian network as a probabilistic approximation of the ODE dynamics. Applying Bayesian inference techniques, this approximation was used to perform parameter estimation and sensitivity analysis. Our combined computational and experimental study showed that the antimicrobial response is sensitive to changes in pH and calcium levels, which determines the strength of the crosstalk between CRP and L-ficolin. Our study also revealed differential regulatory effects of C4BP. While C4BP delays but does not decrease the classical complement activation, it attenuates but does not significantly delay the lectin pathway activation. We also found that the major inhibitory role of C4BP is to facilitate the decay of C3 convertase. In summary, the present work elucidates the regulatory mechanisms of the complement system and demonstrates how the bio-pathway machinery maintains the balance between activation and inhibition. The insights we have gained could contribute to the development of therapies targeting the complement system.","Title: A hierarchical method for real-time distance computation among moving convex bodies\nYear: 2000\n\nAbstract: This paper presents the Hierarchical Walk , or H-Walk algorithm, which maintains the distance between two moving convex bodies by exploiting both motion coherence and hierarchical representations. For convex polygons, we prove that H-Walk improves on the classic Lin–Canny and Dobkin–Kirkpatrick algorithms. We have implemented H-Walk for moving convex polyhedra in three dimensions. Experimental results indicate that, unlike previous incremental distance computation algorithms, H-Walk adapts well to variable coherence in the motion and provides consistent performance.","Title: Motion planning under uncertainty for robotic tasks with long time horizons\nYear: 2011\n\nAbstract: Motion planning with imperfect state information is a crucial capability for autonomous robots to operate reliably in uncertain and dynamic environments. Partially observable Markov decision processes (POMDPs) provide a principled general framework for planning under uncertainty. Using probabilistic sampling, point-based POMDP solvers have drastically improved the speed of POMDP planning, enabling us to handle moderately complex robotic tasks. However, robot motion planning tasks with long time horizons remains a severe obstacle for even the fastest point-based POMDP solvers today. This paper proposes Milestone Guided Sampling (MiGS), a new point-based POMDP solver, which exploits state space information to reduce effective planning horizons. MiGS samples a set of points, called milestones, from a robot芒聙聶s state space and constructs a simplified representation of the state space from the sampled milestones. It then uses this representation of the state space to guide sampling in the belief space and tries to capture the essential features of the belief space with a small number of sampled points. Preliminary results are very promising. We tested MiGS in simulation on several difficult POMDPs that model distinct robotic tasks with long time horizons in both 2-D and 3-D environments. These POMDPs are impossible to solve with the fastest point-based solvers today, but MiGS solved them in a few minutes.","Title: What makes some POMDP problems easy to approximate?\nYear: 2007\n\nAbstract: Point-based algorithms have been surprisingly successful in computing approx- imately optimal solutions for partially observable Markov decision processes (POMDPs) in high dimensional belief spaces. In this work, we seek to understand the belief-space properties that allow some POMDP problems to be approximated efficiently and thus help to explain the point-based algorithms' success often ob- served in the experiments. We show that an approximately optimal POMDP so- lution can be computed in time polynomial in the covering number of a reachable belief space, which is the subset of the belief space reachable from a given belief point. We also show that under the weaker condition of having a small covering number for an optimal reachable space, which is the subset of the belief space reachable under an optimal policy, computing an approximately optimal solution is NP-hard. However, given a suitable set of points that \"cover\" an optimal reach- able space well, an approximate solution can be computed in polynomial time. The covering number highlights several interesting properties that reduce the com- plexity of POMDP planning in practice, e.g., fully observed state variables, beliefs with sparse support, smooth beliefs, and circulant state-transition matrices.","Title: The Bridge Test For Sampling Narrow Passages With Probabilistic Roadmap Planners\nYear: 2003\n\nAbstract: Probabilistic roadmap (PRM) planners have been successful in path planning of robots with many degrees of freedom, but narrow passages in a robot's configuration space create significant difficulty for PRM planners. This paper presents a hybrid sampling strategy in the PRM framework for finding paths through narrow passages. A key ingredient of the new strategy is the bridge test, which boosts the sampling density inside narrow passages. The bridge test relies on simple tests of local geometry and can be implemented efficiently in high-dimensional configuration spaces. The strengths of the bridge test and uniform sampling complement each other naturally and are combined to generate the final hybrid sampling strategy. Our planner was tested on point robots and articulated robots in planar workspaces. Preliminary experiments show that the hybrid sampling strategy enables relatively small roadmaps to reliably capture the connectivity of configuration spaces with difficult narrow passages.","Title: Partially Observable Markov Decision Process (POMDP) Technologies for Sign Language Based Human-Computer Interaction\nYear: 2009\n\nAbstract: Sign language (SL) recognition modules in human-computer interaction systems need to be both fast and reliable. In cases where multiple sets of features are extracted from the SL data, the recognition system can speed up processing by taking only a subset of extracted features as its input. However, this should not be realised at the expense of a drop in recognition accuracy. By training different recognizers for different subsets of features, we can formulate the problem as the task of planning the sequence of recognizer actions to apply to SL data, while accounting for the trade-off between recognition speed and accuracy. Partially observable Markov decision processes (POMDPs) provide a principled mathematical framework for such planning problems. A POMDP explicitly models the probabilities of observing various outputs from the individual recognizers and thus maintains a probability distribution (or belief) over the set of possible SL input sentences. It then computes a policy that maps every belief to an action. This allows the system to select actions in real-time during online policy execution, adapting its behaviour according to the observations encountered. We illustrate the POMDP approach with a simple sentence recognition problem and show in experiments the advantages of this approach over \"fixed action\" systems that do not adapt their behaviour in real-time.","Title: Using stochastic roadmap simulation to predict experimental quantities in protein folding kinetics: folding rates and phi-values.\nYear: 2007\n\nAbstract: This paper presents a new method for studying protein folding kinetics. It uses the recently introduced Stochastic Roadmap Simulation (SRS) method to estimate the transition state ensemble (TSE) and predict the rates and the Phi-values for protein folding. The new method was tested on 16 proteins, whose rates and Phi-values have been determined experimentally. Comparison with experimental data shows that our method estimates the TSE much, more accurately than an existing method based on dynamic programming. This improvement leads to better folding-rate predictions. We also compute the mean first passage time of the unfolded states and show that the computed values correlate with experimentally determined folding rates. The results on Phi-value predictions are mixed, possibly due to the simple energy model used in the tests. This is the first time that results obtained from SRS have been compared against a substantial amount of experimental data. The results further validate the SRS method and indicate its potential as a general tool for studying protein folding kinetics.","Title: Randomized Kinodynamic Motion Planning With Moving Obstacles\nYear: 2002\n\nAbstract: A randomized motion planner is presented for robots that must avoid collision with moving obstacles under kinematic and dynamic constraints. This planner samples the robot's state x time space by picking control inputs at random and integrating the equations of motion. The result is a probabilistic roadmap, i.e., a collection of sampled state x time points, called milestones, connected by short admissible trajectories. The planner does not precompute the roadmap; instead, for each planning query, it generates a new roadmap to connect the input initial and goal state x time points. This paper shows that the probability that the planner fails to find a trajectory when one exists quickly goes to 0 as the number of milestones grows. The planner has been tested successfully in both simulated and real environments. In the latter case, a vision module estimates the obstacle motions just before planning, and the planner is then allocated a small amount of time to compute a trajectory. If a change in obstacle motion is detected while the robot executes the planned trajectory, the planner re-computes a trajectory on the fly.","Title: Markov dynamic models for long-timescale protein motion.\nYear: 2010\n\nAbstract: Molecular dynamics (MD) simulation is a well-established method for studying protein motion at the atomic scale. However, it is computationally intensive and generates massive amounts of data. One way of addressing the dual challenges of computation efficiency and data analysis is to construct simplified models of long-timescale protein motion from MD simulation data. In this direction, we propose to use Markov models with hidden states, in which the Markovian states represent potentially overlapping probabilistic distributions over protein conformations. We also propose a principled criterion for evaluating the quality of a model by its ability to predict long-timescale protein motions. Our method was tested on 2D synthetic energy landscapes and two extensively studied peptides, alanine dipeptide and the villin headpiece subdomain (HP-35 NleNle). One interesting finding is that although a widely accepted model of alanine dipeptide contains six states, a simpler model with only three states is equally good for predicting long-timescale motions. We also used the constructed Markov models to estimate important kinetic and dynamic quantities for protein folding, in particular, mean first-passage time. The results are consistent with available experimental measurements.","Title: Digital violin tutor: an integrated system for beginning violin learners\nYear: 2005\n\nAbstract: Prompt feedback is essential for beginning violin learners; however, most amateur learners can only meet with teachers and receive feedback once or twice a week. To help such learners, we have attempted an initial design of Digital Violin Tutor (DVT), an integrated system that provides the much-needed feedback when human teachers are not available. DVT combines violin audio transcription with visualization. Our transcription method is fast, accurate, and robust again noise for violin audio recorded in home environments. The visualization is designed to be intuitive and easily understandable by people with little music knowledge. The different visualization modalities--video, 2D fingerboard animation, 3D avatar animation--help learners to practice and learn more effectively. The entire system has been implemented with off-the-shelf hardware and shown to be practical in home environments. In our user study, the system has received very positive evaluation.","Title: Exploration in Interactive Personalized Music Recommendation: A Reinforcement Learning Approach\nYear: 2013\n\nAbstract: Current music recommender systems typically act in a greedy manner by recommending songs with the highest user ratings. Greedy recommendation, however, is suboptimal over the long term: it does not actively gather information on user preferences and fails to recommend novel songs that are potentially interesting. A successful recommender system must balance the needs to explore user preferences and to exploit this information for recommendation. This article presents a new approach to music recommendation by formulating this exploration-exploitation trade-off as a reinforcement learning task. To learn user preferences, it uses a Bayesian model that accounts for both audio content and the novelty of recommendations. A piecewise-linear approximation to the model and a variational inference algorithm help to speed up Bayesian inference. One additional benefit of our approach is a single unified model for both music recommendation and playlist generation. We demonstrate the strong potential of the proposed approach with simulation results and a user study.","Title: Protein conformational flexibility analysis with noisy data.\nYear: 2008\n\nAbstract: Protein conformational changes play a critical role in biological functions such as ligand-protein and protein-protein interactions. Due to the noise in structural data, determining salient conformational changes reliably and efficiently is a challenging problem. This paper presents an efficient algorithm for analyzing protein conformational changes, when the data is noisy. It applies a statistical flexibility test to all contiguous fragments of a protein and combines the information from these tests to compute a consensus flexibility measure for each residue of the protein. We tested the algorithm using data from the Protein Data Bank and the Macromolecular Movements Database. The results show that our algorithm can reliably detect different types of salient conformational changes, including well-known examples such as hinge and shear, as well as the flap motion of HIV-1 protease. The software implementing our algorithm is available at http://motion.comp.nus.edu.sg/projects/proflexana/ proflexana.html.","Title: Stealth Tracking of an Unpredictable Target among Obstacles.\nYear: 2004\n\nAbstract: This papers introduces the stealth tracking problem, in which a robot, equipped with visual sensors, tries to track a moving target among obstacles and, at the same time, remain hidden from the target. Obstacles impede both the tracker's motion and visibility, but on the other hand, provide hiding places for the tracker. Our proposed tracking algorithm uses only local information from the tracker's visual sensors and assumes no prior knowledge of target motion or a global map of the environment. It applies a local greedy strategy, and chooses the best move at each time step by minimizing the target's escape risk, subject to the stealth constraint. The algorithm is efficient, taking O(n) time at each step, where n is the complexity of the tracker's visibility region. Simulation experiments show that the algorithm performs well in difficult environments.","Title: Characterization of structural variants with single molecule and hybrid sequencing approaches.\nYear: 2014\n\nAbstract: Motivation: Structural variation is common in human and cancer genomes. High-throughput DNA sequencing has enabled genome-scale surveys of structural variation. However, the short reads produced by these technologies limit the study of complex variants, particularly those involving repetitive regions. Recent 'third-generation' sequencing technologies provide single-molecule templates and longer sequencing reads, but at the cost of higher per-nucleotide error rates. Results: We present MultiBreak-SV, an algorithm to detect structural variants (SVs) from single molecule sequencing data, paired read sequencing data, or a combination of sequencing data from different platforms. We demonstrate that combining low-coverage third-generation data from Pacific Biosciences (PacBio) with high-coverage paired read data is advantageous on simulated chromosomes. We apply MultiBreak-SV to PacBio data from four human fosmids and show that it detects known SVs with high sensitivity and specificity. Finally, we perform a whole-genome analysis on PacBio data from a complete hydatidiform mole cell line and predict 1002 high-probability SVs, over half of which are confirmed by an Illumina-based assembly.","Title: Path planning in expansive configuration spaces\nYear: 1997\n\nAbstract: We introduce the notion of expansiveness to characterize a family of robot configuration spaces whose connectivity can be effectively captured by a roadmap of randomly-sampled milestones. The analysis of expansive configuration spaces has inspired us to develop a new randomized planning algorithm. This algorithm tries to sample only the portion of the configuration space that is relevant to the current query, avoiding the cost of precomputing a roadmap for the entire configuration space. Thus, it is well-suited for problems where a single query is submitted for a given environment. The algorithm has been implemented and successfully applied to complex assembly maintainability problems from the automotive industry","Title: Adaptively combining multiple sampling strategies for probabilistic roadmap planning\nYear: 2004\n\nAbstract: Several sophisticated sampling strategies have been proposed recently to address the narrow passage problem for probabilistic roadmap (PRM) planning. They all have unique strengths and weaknesses in different environments, but in general, none seems sufficient on its own. In this paper, we present a new approach that adaptively combines multiple sampling strategies for PRM planning. Using this approach, we describe an adaptive hybrid sampling (AHS) strategy using two component samplers: the bridge test, a specialized sampler for narrow passages, and the uniform sampler. We tested the AHS strategy on robots with two to eight degrees of freedom. These preliminary tests show that the AHS strategy achieves consistently good performance, compared with fixed-weight hybrid sampling strategies.","Title: Hybrid PRM Sampling with a Cost-Sensitive Adaptive Strategy\nYear: 2005\n\nAbstract: A number of advanced sampling strategies have been proposed in recent years to address the narrow passage problem for probabilistic roadmap (PRM) planning. These sampling strategies all have unique strengths, but none of them solves the problem completely. In this paper, we present a general and systematic approach for adaptively combining multiple sampling strategies so that their individual strengths are preserved. We have performed experiments with this approach on robots with up to 12 degrees of freedom in complex 3-D environments. Experiments show that although the performance of individual sampling strategies varies across different environments, the adaptive hybrid sampling strategies constructed with this approach perform consistently well in all environments. Further, we show that, under reasonable assumptions, the adaptive strategies are provably competitive against all individual strategies used.","Title: Kinodynamic motion planning amidst moving obstacles\nYear: 2000\n\nAbstract: This paper presents a randomized motion planner for kinodynamic asteroid avoidance problems, in which a robot must avoid collision with moving obstacles under kinematic, dynamic constraints and reach a specified goal state. Inspired by probabilistic-roadmap (PRM) techniques, the planner samples the state x time space of a robot by picking control inputs at random in order to compute a roadmap that captures the connectivity of the space. However, the planner does not precompute a roadmap as most PRM planners do. Instead, for each planning query, it generates, on the fly, a small roadmap that connects the given initial and goal state. In contrast to PRM planners, the roadmap computed by our algorithm is a directed graph oriented along the time axis of the space. To verify the planner's effectiveness in practice, we tested it both in simulated environments containing many moving obstacles and on a real robot under strict dynamic constraints. The efficiency of the planner makes it possible for a robot to respond to a changing environment without knowing the motion of moving obstacles well in advance","Title: A greedy strategy for tracking a locally predictable target among obstacles\nYear: 2006\n\nAbstract: Target tracking among obstacles is an interesting class of motion planning problems that combine the usual motion constraints with robot sensors' visibility constraints. In this paper, we introduce the notion of vantage time and use it to formulate a risk function that evaluates the robot's advantage in maintaining the visibility constraint against the target. Local minimization of the risk function leads to a greedy tracking strategy. We also use simple velocity prediction on the target to further improve tracking performance. We compared our new strategy with earlier work in extensive simulation experiments and obtained much improved results. I. INTRODUCTION The target tracking problem considers motion strategies for an autonomous mobile robot to track a moving target among obstacles, i.e., to keep the target within the robot sensor's visibility region. Target tracking has many applications. In home care settings, a tracking robot can follow elderly people around and alert caregivers of emergencies. In security and surveillance systems, tracking strategies enable mobile sensors to monitor moving targets in cluttered environments. Target tracking is an especially interesting class of motion planning problems. Just as in classic motion planning (7), we must consider motion constraints resulting from both obstacles in the environment and the robot's mechanical limitations. In particular, the robot must not collide with obstacles. Target tracking has the additional visibility constraints due to sensor limitations, e.g., obstacles blocking the view of the robot's camera. The robot must move in such a way that the target remains visible at all times. Both motion constraints and visibility constraints play important roles in target tracking. Inspired by earlier work (5), we propose a greedy strategy for target tracking. It uses the robot's sensor to acquire local information on the target and the environment, and use this information to compute the robot's motion at each step. Thus, it does not need ap rioriknowledge of the environment or localization with respect to (w.r.t.) a global map. The key element of the greedy strategy is a local function ϕ that gives a combined estimate of the immediate risk of losing the target and the future risk. Our definition of ϕ is based on two important considerations: • Vantage time, which is a combined estimate of the robot's ability to maneuver against the target in both the current and future time. • The target's instantaneous velocity, which can be esti- mated locally, indicates the target's future movement. We show that by leveraging these two considerations, our new strategy achieves significant improvement in performance over the earlier strategy presented in (5). In the following, after a brief review of related work (Section II), we state the target tracking problem formally (Section III) and present our solution (Section IV). We have implemented the new tracking strategy and compared it with an existing one in simulated environments. The simulation results are shown in Section V. Finally, we conclude with some remarks on future research directions (Section VI).","Title: Adaptive informative path planning in metric spaces\nYear: 2014\n\nAbstract: AbstractIn contrast to classic geometric motion planning, informative path planning IPP seeks a path for a robot to sense the world and gain information. In adaptive IPP, the robot chooses the next sensing location conditioned on all information acquired so far, and the robot's goal is to minimize the travel cost required for identifying a true hypothesis. Adaptive IPP is NP-hard, because the robot must trade-off information gain and travel cost optimally. In this paper we present Recursive Adaptive Identification RAId, a new polynomial-time approximation algorithm for adaptive IPP. We prove a polylogarithmic approximation bound when the robot travels in a metric space. Furthermore, our experiments suggest that RAId is practical and provides good approximate solutions for two distinct robot planning tasks. Although RAId is designed primarily for noiseless observations, a simple extension allows it to handle some tasks with noisy observations.","Title: Learning Dynamic Robot-to-Human Object Handover from Human Feedback\nYear: 2015\n\nAbstract: Object handover is a basic, but essential capability for robots interacting with humans in many applications, e.g., caring for the elderly and assisting workers in manufacturing workshops. It appears deceptively simple, as humans perform object handover almost flawlessly. The success of humans, however, belies the complexity of object handover as collaborative physical interaction between two agents with limited communication. This paper presents a learning algorithm for dynamic object handover, for example, when a robot hands over water bottles to marathon runners passing by the water station. We formulate the problem as contextual policy search, in which the robot learns object handover by interacting with the human. A key challenge here is to learn the latent reward of the handover task under noisy human feedback. Preliminary experiments show that the robot learns to hand over a water bottle naturally and that it adapts to the dynamics of human motion. One challenge for the future is to combine the model-free learning algorithm with a model-based planning approach and enable the robot to adapt over human preferences and object characteristics, such as shape, weight, and surface texture.","Title: Intention-aware online POMDP planning for autonomous driving in a crowd\nYear: 2015\n\nAbstract: This paper presents an intention-aware online planning approach for autonomous driving amid many pedestrians. To drive near pedestrians safely, efficiently, and smoothly, autonomous vehicles must estimate unknown pedestrian intentions and hedge against the uncertainty in intention estimates in order to choose actions that are effective and robust. A key feature of our approach is to use the partially observable Markov decision process (POMDP) for systematic, robust decision making under uncertainty. Although there are concerns about the potentially high computational complexity of POMDP planning, experiments show that our POMDP-based planner runs in near real time, at 3 Hz, on a robot golf cart in a complex, dynamic environment. This indicates that POMDP planning is improving fast in computational efficiency and becoming increasingly practical as a tool for robot planning under uncertainty.","Title: PLEASE: Palm Leaf Search for POMDPs with Large Observation Spaces\nYear: 2015\n\nAbstract: Trial-based asynchronous value iteration algorithms for large Partially Observable Markov Decision Processes (POMDPs), such as HSVI2, FSVI and SARSOP, have made impressive progress in the past decade. In the forward exploration phase of these algorithms, only the outcome that has the highest potential impact is searched. This paper provides a novel approach, called Palm LEAf SEarch (PLEASE), which allows the selection of more than one outcome when their potential impacts are close to the highest one. Compared with existing trial-based algorithms, PLEASE can save considerable time to propagate the bound improvements of beliefs in deep levels of the search tree to the root belief because of fewer point-based value backups. Experiments show that PLEASE scales up SARSOP, one of the fastest algorithms, by orders of magnitude on some POMDP tasks with large observation spaces.","Title: Synthetical Benchmarking of Service Robots: A First Effort on Domestic Mobile Platforms.\nYear: 2015\n\nAbstract: Most of existing benchmarking tools for service robots are basically qualitative, in which a robot's performance on a task is evaluated based on completion/incompletion of actions contained in the task. In the effort reported in this paper, we tried to implement a synthetical benchmarking system on domestic mobile platforms. Synthetical benchmarking consists of both qualitative and quantitative aspects, such as task completion, accuracy of task completions and efficiency of task completions, about performance of a robot. The system includes a set of algorithms for collecting, recording and analyzing measurement data from a MoCap system. It was used as the evaluator in a competition called the BSR challenge, in which 10 teams participated, at RoboCup 2015. The paper presents our motivations behind synthetical benchmarking, the design considerations on the synthetical benchmarking system, the realization of the competition as a comparative study on performance evaluation of domestic mobile platforms, and an analysis of the teams' performance.","Title: Adaptive Stochastic Optimization: From Sets to Paths\nYear: 2015\n\nAbstract: Adaptive stochastic optimization (ASO) optimizes an objective function adaptively under uncertainty. It plays a crucial role in planning and learning under uncertainty, but is, unfortunately, computationally intractable in general. This paper introduces two conditions on the objective function, the marginal likelihood rate bound and the marginal likelihood bound, which, together with pointwise submodularity, enable efficient approximate solution of ASO. Several interesting classes of functions satisfy these conditions naturally, e.g., the version space reduction function for hypothesis learning. We describe Recursive Adaptive Coverage, a new ASO algorithm that exploits these conditions, and apply the algorithm to two robot planning tasks under uncertainty. In contrast to the earlier submodular optimization approach, our algorithm applies to ASO over both sets and paths.","Title: DESPOT: Online POMDP Planning with Regularization.\nYear: 2017\n\nAbstract: The partially observable Markov decision process (POMDP) provides a principled general framework for planning under uncertainty, but solving POMDPs optimally is computationally intractable, due to the \"curse of dimensionality\" and the \"curse of history\". To overcome these challenges, we introduce the Determinized Sparse Partially Observable Tree (DESPOT), a sparse approximation of the standard belief tree, for online planning under uncertainty. A DESPOT focuses online planning on a set of randomly sampled scenarios and compactly captures the \"execution\" of all policies under these scenarios. We show that the best policy obtained from a DESPOT is near-optimal, with a regret bound that depends on the representation size of the optimal policy. Leveraging this result, we give an anytime online planning algorithm, which searches a DESPOT for a policy that optimizes a regularized objective function. Regularization balances the estimated value of a policy under the sampled scenarios and the policy size, thus avoiding overfitting. The algorithm demonstrates strong experimental results, compared with some of the best online POMDP algorithms available. It has also been incorporated into an autonomous driving system for real-time vehicle control. The source code for the algorithm is available online.","Title: Human-Robot Mutual Adaptation in Shared Autonomy.\nYear: 2017\n\nAbstract: Shared autonomy integrates user input with robot autonomy in order to control a robot and help the user to complete a task. Our work aims to improve the performance of such a human-robot team: the robot tries to guide the human towards an effective strategy, sometimes against the human's own preference, while still retaining his trust. We achieve this through a principled human-robot mutual adaptation formalism. We integrate a bounded-memory adaptation model of the human into a partially observable stochastic decision model, which enables the robot to adapt to an adaptable human. When the human is adaptable, the robot guides the human towards a good strategy, maybe unknown to the human in advance. When the human is stubborn and not adaptable, the robot complies with the human's preference in order to retain their trust. In the shared autonomy setting, unlike many other common human-robot collaboration settings, only the robot actions can change the physical state of the world, and the human and robot goals are not fully observable. We address these challenges and show in a human subject experiment that the proposed mutual adaptation formalism improves human-robot team performance, while retaining a high level of user trust in the robot, compared to the common approach of having the robot strictly following participants' preference.","Title: Factored Contextual Policy Search with Bayesian Optimization.\nYear: 2016\n\nAbstract: Scarce data is a major challenge to scaling robot learning to truly complex tasks, as we need to generalize locally learned policies over different Bayesian optimization approaches to contextual policy search (CPS) offer data-efficient policy learning that generalize over a context space. We propose to improve data- efficiency by factoring typically considered contexts into two components: target- type contexts that correspond to a desired outcome of the learned behavior, e.g. target position for throwing a ball; and environment type contexts that correspond to some state of the environment, e.g. initial ball position or wind speed. Our key observation is that experience can be directly generalized over target-type contexts. Based on that we introduce Factored Contextual Policy Search with Bayesian Optimization for both passive and active learning settings. Preliminary results show faster policy generalization on a simulated toy problem.","Title: Robots in Harmony with Humans.\nYear: 2016\n\nAbstract: In early days, robots often occupied tightly controlled environments, for example, factory floors, designed to segregate robots and humans for safety. Today robots live with humans, providing a variety of services at homes, in workplaces, or on the road. To become effective and trustworthy collaborators, robots must understand human intentions and act accordingly in response. One core challenge here is the inherent uncertainty in understanding intentions, as a result of the complexity and diversity of human behaviours. Robots must hedge against such uncertainties to achieve robust performance and sometimes actively elicit information in order to reduce uncertainty and ascertain human intentions. Our recent work explores planning and learning under uncertainty for human-robot interactive or collaborative tasks. It covers mathematical models for human intentions, planning algorithms that connect robot perception with decision making, and learning algorithms that enable robots to adapt to human preferences. The work, I hope, will spur greater interest towards principled approaches that integrate perception, planning, and learning for fluid human-robot collaboration.","Title: Supermodular Mean Squared Error Minimization For Sensor Scheduling In Optimal Kalman Filtering\nYear: 2017\n\nAbstract: We consider the problem of scheduling a set of sensors to observe the state of a discrete-time linear system subject to a limited energy budget. Our goal is to devise a sensor schedule that minimizes the mean squared error (MSE) of an optimal estimator (i.e., the Kalman Filter). Both the minimum-MSE and the minimum-cardinality optimal sensor scheduling problems are inherently combinatorial, and computationally intractable. We remedy the combinatorial complexity by using a greedy heuristic; the greedy heuristic is guaranteed to return near-optimal solutions when minimizing supermodular objectives. While it is known that the MSE is not supermodular (with counterexamples available in literature), we provide conditions on the prior information matrix and on the observation matrix under which supermodularity holds. More specifically, we require the prior information matrix to be a strictly-diagonally-dominant M-matrix (plus an extra technical requirement on its inverse). Empirical results confirm that random M-matrices lead to supermodular problems, while this is not the case for generic prior information matrices. M- matrices naturally arise in estimation problems over networks and we provide a practical application of our findings to an energy-constrained multi robot localization problem.","Title: Mathematical Models of Adaptation in Human-Robot Collaboration.\nYear: 2017\n\nAbstract: A robot operating in isolation needs to reason over the uncertainty in its model of the world and adapt its own actions to account for this uncertainty. Similarly, a robot interacting with people needs to reason over its uncertainty over the human internal state, as well as over how this state may change, as humans adapt to the robot. This paper summarizes our own work in this area, which depicts the different ways that probabilistic planning and game-theoretic algorithms can enable such reasoning in robotic systems that collaborate with people. We start with a general formulation of the problem as a two-player game with incomplete information. We then articulate the different assumptions within this general formulation, and we explain how these lead to exciting and diverse robot behaviors in real-time interactions with actual human subjects, in a variety of manufacturing, personal robotics and assistive care settings.","Title: Grounding Spatio-Semantic Referring Expressions for Human-Robot Interaction.\nYear: 2017\n\nAbstract: The human language is one of the most natural interfaces for humans to interact with robots. This paper presents a robot system that retrieves everyday objects with unconstrained natural language descriptions. A core issue for the system is semantic and spatial grounding, which is to infer objects and their spatial relationships from images and natural language expressions. We introduce a two-stage neural-network grounding pipeline that maps natural language referring expressions directly to objects in the images. The first stage uses visual descriptions in the referring expressions to generate a candidate set of relevant objects. The second stage examines all pairwise relationships between the candidates and predicts the most likely referred object according to the spatial descriptions in the referring expressions. A key feature of our system is that by leveraging a large dataset of images labeled with text descriptions, it allows unrestricted object types and natural language referring expressions. Preliminary results indicate that our system outperforms a near state-of-the-art object comprehension system on standard benchmark datasets. We also present a robot system that follows voice commands to pick and place previously unseen objects.","Title: Shortest Path Under Uncertainty: Exploration Versus Exploitation\nYear: 2017\n\nAbstract: In the Canadian Traveler Problem (CTP), a traveler seeks a shortest path to a destination through a road network, but unknown to the traveler, some roads may be blocked. This paper studies the Bayesian CTP (BCTP), in which road states are correlated with known prior probabilities and the traveler can infer the states of an unseen road from past observations of other correlated roads. As generalized shortest-path problems, CTP and BCTP have important practical applications. We show that BCTP is NP-complete and give a polynomial-time approximation algorithm, Hedged Shortest Path under Determinization (HSPD), which approximates an optimal solution with a polylogarithmic factor. Preliminary experiments show promising results. HSPD outperforms a widely used greedy algorithm and a state-of-the-art UCT-based search algorithm for CTP, especially when significant exploration is required.","Title: Intention-Net: Integrating Planning and Deep Learning for Goal-Directed Autonomous Navigation.\nYear: 2017\n\nAbstract: How can a delivery robot navigate reliably to a destination in a new office building, with minimal prior information? To tackle this challenge, this paper introduces a two-level hierarchical approach, which integrates model-free deep learning and model-based path planning. At the low level, a neural-network motion controller, called the intention-net, is trained end-to-end to provide robust local navigation. The intention-net maps images from a single monocular camera and directly to robot controls. At the high level, a path planner uses a crude map, e.g., a 2-D floor plan, to compute a path from the robotu0027s current location to the goal. The planned path provides intentions to the intention-net. Preliminary experiments suggest that the learned motion controller is robust against perceptual uncertainty and by integrating with a path planner, it generalizes effectively to new environments and goals.","Title: Human-robot mutual adaptation in collaborative tasks\nYear: 2017\n\nAbstract: AbstractAdaptation is critical for effective team collaboration. This paper introduces a computational formalism for mutual adaptation between a robot and a human in collaborative tasks. We propose the Bounded-Memory Adaptation Model, which is a probabilistic finite-state controller that captures human adaptive behaviors under a bounded-memory assumption. We integrate the Bounded-Memory Adaptation Model into a probabilistic decision process, enabling the robot to guide adaptable participants towards a better way of completing the task. Human subject experiments suggest that the proposed formalism improves the effectiveness of human-robot teams in collaborative tasks, when compared with one-way adaptations of the robot to the human, while maintaining the human's trust in the robot.","Title: Planning with Trust for Human-Robot Collaboration.\nYear: 2018\n\nAbstract: Trust is essential for human-robot collaboration and user adoption of autonomous systems, such as robot assistants. This paper introduces a computational model which integrates trust into robot decision-making. Specifically, we learn from data a partially observable Markov decision process (POMDP) with human trust as a latent variable. The trust-POMDP model provides a principled approach for the robot to (i) infer the trust of a human teammate through interaction, (ii) reason about the effect of its own actions on human behaviors, and (iii) choose actions that maximize team performance over the long term. We validated the model through human subject experiments on a table-clearing task in simulation (201 participants) and with a real robot (20 participants). The results show that the trust-POMDP improves human-robot team performance in this task. They further suggest that maximizing trust in itself may not improve team performance.","Title: Human Trust in Robot Capabilities across Tasks.\nYear: 2018\n\nAbstract: In this work, we study how humans transfer or generalize trust in robot capabilities across tasks, even with limited observations. We present results from a human-subjects experiment using a real-world Fetch robot performing household tasks. In summary, we find that human trust generalization is influenced by perceived task similarity, difficulty, and robot performance.","Title: Autonomous Driving among Many Pedestrians: Models and Algorithms.\nYear: 2018\n\nAbstract: Driving among a dense crowd of pedestrians is a major challenge for autonomous vehicles. This paper presents a planning system for autonomous driving among many pedestrians. A key ingredient of our approach is a pedestrian motion prediction model that accounts for both a pedestrianu0027s global navigation intention and local interactions with the vehicle and other pedestrians. Unfortunately, the autonomous vehicle does not know the pedestrianu0027s intention a priori and requires a planning algorithm that hedges against the uncertainty in pedestrian intentions. Our planning system combines a POMDP algorithm with the pedestrian motion model and runs in near real time. Experiments show that it enables a robot vehicle to drive safely, efficiently, and smoothly among a crowd with a density of nearly one person per square meter.","Title: Integrating Algorithmic Planning and Deep Learning for Partially Observable Navigation.\nYear: 2018\n\nAbstract: We propose to take a novel approach to robot system design where each building block of a larger system is represented as a differentiable program, i.e. a deep neural network. This representation allows for integrating algorithmic planning and deep learning in a principled manner, and thus combine the benefits of model-free and model-based methods. We apply the proposed approach to a challenging partially observable robot navigation task. The robot must navigate to a goal in a previously unseen 3-D environment without knowing its initial location, and instead relying on a 2-D floor map and visual observations from an onboard camera. We introduce the Navigation Networks (NavNets) that encode state estimation, planning and acting in a single, end-to-end trainable recurrent neural network. In preliminary simulation experiments we successfully trained navigation networks to solve the challenging partially observable navigation task.","Title: Particle Filter Networks with Application to Visual Localization.\nYear: 2018\n\nAbstract: Particle filtering is a powerful approach to sequential state estimation and finds application in many domains, including robot localization, object tracking, etc. To apply particle filtering in practice, a critical challenge is to construct probabilistic system models, especially for systems with complex dynamics or rich sensory inputs such as camera images. This paper introduces the Particle Filter Network (PFnet), which encodes both a system model and a particle filter algorithm in a single neural network. The PF-net is fully differentiable and trained end-to-end from data. Instead of learning a generic system model, it learns a model optimized for the particle filter algorithm. We apply the PF-net to a visual localization task, in which a robot must localize in a rich 3-D world, using only a schematic 2-D floor map. In simulation experiments, PF-net consistently outperforms alternative learning architectures, as well as a traditional model-based method, under a variety of sensor inputs. Further, PF-net generalizes well to new, unseen environments.","Title: PORCA: Modeling and Planning for Autonomous Driving Among Many Pedestrians.\nYear: 2018\n\nAbstract: This letter presents a planning system for autonomous driving among many pedestrians. A key ingredient of our approach is Pedestrian Optimal Reciprocal Collision Avoidance, a pedestrian motion prediction model that accounts for both a pedestrian's global navigation intention and local interactions with the vehicle and other pedestrians. Unfortunately, the autonomous vehicle does not know the pedes...","Title: Guided Exploration of Human Intentions for Human-Robot Interaction.\nYear: 2018\n\nAbstract: Robot understanding of human intentions is essential for fluid human-robot interaction. Intentions, however, cannot be directly observed and must be inferred from behaviors. We learn a model of adaptive human behavior conditioned on the intention as a latent variable. We then embed the human behavior model into a principled probabilistic decision model, which enables the robot to (i) explore actively in order to infer human intentions and (ii) choose actions that maximize its performance. Furthermore, the robot learns from the demonstrated actions of human experts to further improve exploration. Preliminary experiments in simulation indicate that our approach, when applied to autonomous driving, improves the efficiency and safety of driving in common interactive driving scenarios.","Title: Workspace-Based Connectivity Oracle: An Adaptive Sampling Strategy for PRM Planning\nYear: 2006\n\nAbstract: This paper presents Workspace-based Connectivity Oracle (WCO), a dynamic sampling strategy for probabilistic roadmap planning. WCO uses both domain knowledge-specifically, workspace geometry-and sampling history to construct dynamic sampling distributions. It is composed of many component samplers, each based on a geometric feature of a robot. A component sampler updates its distribution, using information from the workspace geometry and the current state of the roachmap being constructed. These component samplers are combined through the adaptive hybrid sampling approach, based on their sampling histories. In the tests on rigid and articulated robots in 2-D and 3-D workspaces, WCO showed strong performance, compared with sampling strategies that use dynamic sampling or workspace information alone.","Title: Importance sampling for online planning under uncertainty\nYear: 2019\n\nAbstract: AbstractThe partially observable Markov decision process (POMDP) provides a principled general framework for robot planning under uncertainty. Leveraging the idea of Monte Carlo sampling, recent POMDP planning algorithms have scaled up to various challenging robotic tasks, including, real-time online planning for autonomous vehicles. To further improve online planning performance, this paper presents IS-DESPOT, which introduces importance sampling to DESPOT, a state-of-the-art sampling-based POMDP algorithm for planning under uncertainty. Importance sampling improves DESPOT’s performance when there are critical, but rare events, which are difficult to sample. We prove that IS-DESPOT retains the theoretical guarantee of DESPOT. We demonstrate empirically that importance sampling significantly improves the performance of online POMDP planning for suitable tasks. We also present a general method for learning the importance sampling distribution.","Title: Robot Capability and Intention in Trust-Based Decisions Across Tasks\nYear: 2019\n\nAbstract: In this paper, we present results from a human-subject study designed to explore two facets of human mental models of robots---inferred capability and intention---and their relationship to overall trust and eventual decisions. In particular, we examine delegation situations characterized by uncertainty, and explore how inferred capability and intention are applied across different tasks. We develop an online survey where human participants decide whether to delegate control to a simulated UAV agent. Our study shows that human estimations of robot capability and intent correlate strongly with overall self-reported trust. However, overall trust is not independently sufficient to determine whether a human will decide to trust (delegate) a given task to a robot. Instead, our study reveals that estimations of robot intention, capability, and overall trust are integrated when deciding to delegate. From a broader perspective, these results suggest that calibrating overall trust alone is insufficient; to make correct decisions, humans need (and use) multi-faceted mental models when collaborating with robots across multiple contexts.","Title: Ab Initio Particle-Based Object Manipulation\nYear: 2021\n\nAbstract: Particle-based Object Manipulation (PROMPT) is a new method for robot manipulation of novel objects, without prior object models or pre-training on a large object data set. The key element of PROMPT is a particle-based object representation, in which each particle represents a point in an object, the local geometric, physical, and other features of the point, and also its relation with other particles. The particle representation connects visual perception with robot control. Like data-driven methods, PROMPT infers the object representation online in real time from the visual sensor. Like model-based methods, PROMPT leverages the particle representation to reason about the object's geometry and dynamics, and choose suitable manipulation actions accordingly. PROMPT thus combines the strengths of model-based and data-driven methods. We show empirically that PROMPT successfully handles a variety of everyday objects, some of which are transparent. It handles various manipulation tasks, including grasping, pushing, etc.. Our experiments also show that PROMPT outperforms a state-of-the-art data-driven grasping method on everyday household objects, even though it does not use any offline training data. The code and a demonstration video are available online.","Title: Magic: Learning Macro-Actions For Online Pomdp Planning\nYear: 2021\n\nAbstract: The partially observable Markov decision process (POMDP) is a principled general framework for robot decision making under uncertainty, but POMDP planning suffers from high computational complexity, when long-term planning is required. While temporally-extended macro-actions help to cut down the effective planning horizon and significantly improve computational efficiency, how do we acquire good macroactions? This paper proposes Macro-Action Generator-Critic (MAGIC), which performs offline learning of macro-actions optimized for online POMDP planning. Specifically, MAGIC learns a macro-action generator end-to-end, using an online planner's performance as the feedback. During online planning, the generator generates on the fly situation-aware macro-actions conditioned on the robot's belief and the environment context. We evaluated MAGIC on several long-horizon planning tasks both in simulation and on a real robot. The experimental results show that the learned macro-actions offer significant benefits in online planning performance, compared with primitive actions and handcrafted macro-actions.","Title: Invigorate: Interactive Visual Grounding And Grasping In Clutter\nYear: 2021\n\nAbstract: This paper presents INVIGORATE, a robot system that interacts with human through natural language and grasps a specified object in clutter. The objects may occlude, obstruct, or even stack on top of one another. INVIGORATE embodies several challenges: (i) infer the target object among other occluding objects, from input language expressions and RGB images, (ii) infer object blocking relationships (OBRs) from the images, and (iii) synthesize a multi-step plan to ask questions that disambiguate the target object and to grasp it successfully. We train separate neural networks for object detection, for visual grounding, for question generation, and for OBR detection and grasping. They allow for unrestricted object categories and language expressions, subject to the training datasets. However, errors in visual perception and ambiguity in human languages are inevitable and negatively impact the robot's performance. To overcome these uncertainties, we build a partially observable Markov decision process (POMDP) that integrates the learned neural network modules. Through approximate POMDP planning, the robot tracks the history of observations and asks disambiguation questions in order to achieve a near-optimal sequence of actions that identify and grasp the target object. INVIGORATE combines the benefits of model-based POMDP planning and data-driven deep learning. Preliminary experiments with INVIGORATE on a Fetch robot show significant benefits of this integrated approach to object grasping in clutter with natural language interactions. A demonstration video is available online.(1)","Title: Interactive Planning for Autonomous Urban Driving in Adversarial Scenarios 2021\nYear: 2021\n\nAbstract: Autonomous urban driving among human-driven cars requires a holistic understanding of road rules, driver intents and driving styles. This is challenging as a short-term, single instance, driver intent of lane change may not correspond to their driving styles for a longer duration. This paper presents an interactive behavior planner which accounts for road context, short-term driver intent, and long-term driving style to infer beliefs over the latent states of surrounding vehicles. We use a specialized Partially Observable Markov Decision Process to provide risk-averse decisions. Specifically, we consider adversarial driving scenarios caused by irrational drivers to validate the robustness of our proposed interactive behavior planner in simulation as well as on a full-size selfdriving car. Our experimental results show that our algorithm enables safer and more travel time-efficient autonomous driving compared to baselines even in adversarial scenarios.","Title: GAMMA: A General Agent Motion Model for Autonomous Driving\nYear: 2022\n\nAbstract: This letter presents GAMMA, a general motion prediction model that enables large-scale real-time simulation and planning for autonomous driving. GAMMA models heterogeneous, interactive traffic agents that operate under diverse road conditions, with various geometric and kinematic constraints. GAMMA treats the prediction task as constrained optimization in traffic agents' velocity space. The objective is to optimize an agent's driving performance, while obeying all the constraints resulting from the agent's kinematics, collision avoidance with other agents, and the environmental context. Further, GAMMA explicitly conditions the prediction on human behavioral states as parameters of the optimization model, in order to account for versatile human behaviors. We evaluated GAMMA on a set of real-world benchmark datasets. The results show that GAMMA achieves high prediction accuracy on both homogeneous and heterogeneous traffic datasets, with sub-millisecond execution time. Further, the computational efficiency and the flexibility of GAMMA enable (i) simulation of mixed urban traffic at many locations worldwide and (ii) planning for autonomous driving in dense traffic with uncertain driver behaviors, both in real-time. The open-source code of GAMMA is available online."],"string":"[\n \"Title: A point-based POMDP planner for target tracking\\nYear: 2008\\n\\nAbstract: Abstract—Target,tracking,has two,variants,that are often studied independently,with different approaches: target search- ing requires a robot to find a target initially not visible, and,target following,requires,a robot,to maintain,visibility on a target initially visible. In this work, we use a partially observable,Markov,decision process (POMDP) to build a single model,that unifies target searching,and,target following. The POMDP solution exhibits interesting tracking behaviors, such as anticipatory moves that exploit target dynamics, information- gathering moves that reduce target position uncertainty, and energy-conserving actions that allow the target to get out of sight, but do not compromise long-term tracking performance. To overcome,the high,computational,complexity,of solving POMDPs, we have developed SARSOP, a new point-based POMDP algorithm,based,on successively approximating,the space reachable,under,optimal,policies. Experimental,results show that SARSOP is competitive with the fastest existing point- based algorithm,on many,standard,test problems,and,faster by many,times on some.\",\n \"Title: Component-based construction of bio-pathway models: The parameter estimation problem\\nYear: 2011\\n\\nAbstract: Constructing and analyzing large biological pathway models is a significant challenge. We propose a general approach that exploits the structure of a pathway to identify pathway components, constructs the component models, and finally assembles the component models into a global pathway model. Specifically, we apply this approach to pathway parameter estimation, a main step in pathway model construction. A large biological pathway often involves many unknown parameters and the resulting high-dimensional search space poses a major computational difficulty. By exploiting the structure of a pathway and the distribution of available experimental data over the pathway, we decompose a pathway into components and perform parameter estimation for each component. However, some parameters may belong to multiple components. Independent parameter estimates from different components may be in conflict for such parameters. To reconcile these conflicts, we represent each component as a factor graph, a standard probabilistic graphical model. We then combine the resulting factor graphs and use a probabilistic inference technique called belief propagation to obtain the maximally likely parameter values that are globally consistent. We validate our approach on a synthetic pathway model based on the Akt-MAPK signaling pathways. The results indicate that the approach can potentially scale up to large pathway models.\",\n \"Title: Computing the largest inscribed isothetic rectangle\\nYear: 1995\\n\\nAbstract: This paper describes an algorithm to compute, in Theta(log n) time, a rectangle that is contained in a convex n-gon, has sides parallel to the coordinate axes, and has maximum area. With a slight modification it will compute the smallest perimeter. The algorithm uses a tentative prune-and-search approach, even though this problem does not appear to fit into the functional framework of Kirkpatrick and Snoeyink.\",\n \"Title: Field-Programmable Learning Arrays\\nYear: 2002\\n\\nAbstract: This paper introduces the Field-Programmable Learning Array, a new paradigm for rapid prototyping of learning primitives and machine- learning algorithms in silicon. The FPLA is a mixed-signal counterpart to the all-digital Field-Programmable Gate Array in that it enables rapid prototyping of algorithms in hardware. Unlike the FPGA, the FPLA is targeted directly for machine learning by providing local, parallel, on- line analog learning using floating-gate MOS synapse transistors. We present a prototype FPLA chip comprising an array of reconfigurable computational blocks and local interconnect. We demonstrate the via- bility of this architecture by mapping several learning circuits onto the prototype chip.\",\n \"Title: Monte Carlo Value Iteration for Continuous-State POMDPs.\\nYear: 2010\\n\\nAbstract: Partially observable Markov decision processes (POMDPs) have been successfully applied to various robot motion planning tasks under uncertainty. However, most existing POMDP algorithms assume a discrete state space, while the natural state space of a robot is often continuous. This paper presents Monte Carlo Value Iteration (MCVI) for continuous-state POMDPs. MCVI samples both a robot's state space and the corresponding belief space, and avoids inefficient a priori discretization of the state space as a grid. Both theoretical results and preliminary experimental results indicate that MCVI is a promising new approach for robot motion planning under uncertainty.\",\n \"Title: Planning how to learn\\nYear: 2013\\n\\nAbstract: When a robot uses an imperfect system model to plan its actions, a key challenge is the exploration-exploitation trade-off between two sometimes conflicting objectives: (i) learning and improving the model, and (ii) immediate progress towards the goal, according to the current model. To address model uncertainty systematically, we propose to use Bayesian reinforcement learning and cast it as a partially observable Markov decision process (POMDP). We present a simple algorithm for offline POMDP planning in the continuous state space. Offline planning produces a POMDP policy, which can be executed efficiently online as a finite-state controller. This approach seamlessly integrates planning and learning: it incorporates learning objectives in the computed plan, which then enables the robot to learn nearly optimally online and reach the goal. We evaluated the approach in simulations on two distinct tasks, acrobot swing-up and autonomous vehicle navigation amidst pedestrians, and obtained interesting preliminary results.\",\n \"Title: A mixed-signal approach to high-performance low-power linear filters\\nYear: 2001\\n\\nAbstract: We present a new approach to the design of high-performance low-power linear filters. We use p-channel synapse transistors as analog memory cells, and mixed-signal circuits for fast low-power arithmetic. To demonstrate the effectiveness of our approach, we have built a 16-tap 7-b 200-MHz mixed-signal finite-impulse response (FIR) filter that consumes 3 mW at 3.3 V. The filter uses synapse pFETs to...\",\n \"Title: Motion Planning for 3-D Target Tracking among Obstacles\\nYear: 2007\\n\\nAbstract: The goal of target tracking is to compute motion strategies for a robot equipped with visual sensors, so that it can effectively track a moving target despite obstruction by obstacles. It is an important problem with many applications in robotics. Existing work focuses mostly on the 2-D version of the problem, partly due to the complexity of dealing with 3-D visibility relationships. This paper proposes an online algorithm for 3-D target tracking among obstacles, using only local geometric information available to a robot's visual sensors. Key to this new algorithm is the definition and efficient computation of a risk function, which tries to capture a target's ability in escaping from the robot sensors' visibility region in both short and long terms. The robot then moves to minimize this risk function locally in a greedy fashion. In the absence of occlusion by obstacles, the standard tracking algorithm based on visual servo control can be considered a special case of our algorithm. Experiments show that the new algorithm generated interesting tracking behaviors in three dimensions and performed substantially better than visual servo control in simulation.\",\n \"Title: Motion Strategies for People Tracking in Cluttered and Dynamic Environments\\nYear: 2008\\n\\nAbstract: The key contribution of this work is the construction of a robot tracking system that follows an unpredictable target (e.g people) in cluttered, unknown and dynamic environments. To do so, mobility constraints, sensor limitations, and uncertainty have been addressed at both the algorithmic and implementation levels. The work formulates target tracking as minimizing an objective function that models the risk of the target's escape and derives this risk function from basic principles. Various practical hardware limitations - e.g., sensor's field of view, safe navigation are taken into account either as part of the risk function or as constraints during risk minimization. The resulting tracker demonstrates substantially improved performance, compared with other local online strategies. The tracker was able to track a person walking around in indoor office environments as well as in a highly dynamic and public environment, like the school cafeteria successfully.\",\n \"Title: A decompositional approach to parameter estimation in pathway modeling: a case study of the Akt and MAPK pathways and their crosstalk.\\nYear: 2006\\n\\nAbstract: Parameter estimation is a critical problem in modeling biological pathways. It is difficult because of the large number of parameters to be estimated and the limited experimental data available. In this paper, we propose a decompositional approach to parameter estimation. It exploits the structure of a large pathway model to break it into smaller components, whose parameters can then be estimated independently. This leads to significant improvements in computational efficiency. We present our approach in the context of Hybrid Functional Petri Net modeling and evolutionary search for parameter value estimation. However, the approach can be easily extended to other modeling frameworks and is independent of the search method used. We have tested our approach on a detailed model of the Akt and MAPK pathways with two known and one hypothesized crosstalk mechanisms. The entire model contains 84 unknown parameters. Our simulation results exhibit good correlation with experimental data, and they yield positive evidence in support of the hypothesized crosstalk between the two pathways.\",\n \"Title: Using robotics to fold proteins and dock ligands.\\nYear: 2002\\n\\nAbstract: The problems of protein folding and ligand docking have been explored largely using molecular dynamics or Monte Carlo methods. These methods are very compute intensive because they often explore a much wider range of energies, conformations and time than necessary. In addition, Monte Carlo methods often get trapped in local minima. We initially showed that robotic motion planning permitted one to determine the energy of binding and dissociation of ligands from protein binding sites (Singh et al., 1999). The robotic motion planning method maps complicated three-dimensional conformational states into a much simpler, but higher dimensional space in which conformational rearrangements can be represented as linear paths. The dimensionality of the conformation space is of the same order as the number of degrees of conformational freedom in three-dimensional space. We were able to determine the relative energy of association and dissociation of a ligand to a protein by calculating the energetics of interaction for a few thousand conformational states in the vicinity of the protein and choosing the best path from the roadmap. More recently, we have applied roadmap planning to the problem of protein folding (Apaydin et al., 2002a). We represented multiple conformations of a protein as nodes in a compact graph with the edges representing the probability of moving between neighboring states. Instead of using Monte Carlo simulation to simulate thousands of possible paths through various conformational states, we were able to use Markov methods to calculate the steady state occupancy of each conformation, needing to calculate the energy of each conformation only once. We referred to this Markov method of representing multiple conformations and transitions as stochastic roadmap simulation or SRS. We demonstrated that the distribution of conformational states calculated with exhaustive Monte Carlo simulations asymptotically approached the Markov steady state if the same Boltzman energy distribution was used in both methods. SRS permits one to calculate contributions from all possible paths simultaneously with far fewer energy calculations than Monte Carlo or molecular dynamics methods. The SRS method also permits one to represent multiple unfolded starting states and multiple, near-native, folded states and all possible paths between them simultaneously. The SRS method is also independent of the function used to calculate the energy of the various conformational states. In a paper to be presented at this conference (Apaydin et al., 2002b) we have also applied SRS to ligand docking in which we calculate the dynamics of ligand-protein association and dissociation in the region of various binding sites on a number of proteins. SRS permits us to determine the relative times of association to and dissociation from various catalytic and non-catalytic binding sites on protein surfaces. Instead of just following the best path in a roadmap, we can calculate the contribution of all the possible binding or dissociation paths and their relative probabilities and energies simultaneously.\",\n \"Title: A piece-wise harmonic Langevin model of EEG dynamics: Theory and application to EEG seizure detection\\nYear: 2005\\n\\nAbstract: Electroencephalogram (EEG) dynamics results from the motion of charged particles in the brain. By invoking the laws of classical physics, we show that EEG dynamics obeys, at short enough times, a piece-wise quadratic Langevin equation characterized by an effective mass matrix, a piece-wise quadratic potential energy surface, a friction and random force matrix. In analyzing a sample seizure, we find with seizure onset a marked increase in the frequency of encounters with inflection points on the potential energy surface.\",\n \"Title: Self-Calibrating Camera Projector Systems for Interactive Displays and Presentations\\nYear: 2001\\n\\nAbstract: IntroductionWe demonstrate a self-calibrating system that employs uncalibratedcameras and microportable projectors to createnovel interactive displays and presentations.1Three benefitsof our system are detailed in the following sections.2. Automatic Keystone CorrectionThe image generated by an off-center projector appearsdistorted (Figure 1, left). Using an uncalibrated camerapointed at the presentation screen, our system automaticallyrecovers the projector-to-screen homography...\",\n \"Title: SARSOP: Efficient Point-Based POMDP Planning by Approximating Optimally Reachable Belief Spaces\\nYear: 2008\\n\\nAbstract: IN Proc. Robotics: Science & Systems, 2008 Abstract—Motion planning in uncertain and dynamic environ- ments is an essential capability for autonomous robots. Partially observable Markov decision processes (POMDPs) provide a principled mathematical framework for solving such problems, but they are often avoided in robotics due to high computational complexity. Our goal is to create practical POMDP algorithms and software for common robotic tasks. To this end, we have developed a new point-based POMDP algorithm that exploits the notion of optimally reachable belief spaces to improve com- putational efficiency. In simulation, we successfully applied the algorithm to a set of common robotic tasks, including instances of coastal navigation, grasping, mobile robot exploration, and target tracking, all modeled as POMDPs with a large number of states. In most of the instances studied, our algorithm substantially outperformed one of the fastest existing point-based algorithms. A software package implementing our algorithm will soon be released at http://motion.comp.nus.edu.sg/ projects/pomdp/pomdp.html.\",\n \"Title: H-Walk: hierarchical distance computation for moving convex bodies\\nYear: 1999\\n\\nAbstract: This paper presents the Hierarchical Walk, or H-Walk al- gorithm, which maintains the distance between two moving convex bodies by exploiting both motion coherence and hi- erarchical representations. For convex polygons, we prove that H-Walk improves on the classic Lin-Canny and Dobkin- Kirkpatrick algorithms. We have implemented H-Walk for moving convex polyhedra in three dimensions. Experimen- tal results indicate that, unlike previous incremental dis- tance computation algorithms, H-Walk adapts well to vari- able coherence in the motion.\",\n \"Title: Workspace Importance Sampling for Probabilistic Roadmap Planning\\nYear: 2004\\n\\nAbstract: Probabilistic Roadmap (PRM) planners have been successful in path planning of robots with many degrees of freedom, but they behave poorly when a robot's configu- ration space contains narrow passages. This paper presents workspace importance sampling (WIS), a new sampling strat- egy for PRM planning. Our main idea is to use geometric information from a robot's workspace as \\\"importance\\\" values to guide sampling in the corresponding configuration space. By doing so, WIS increases the sampling density in narrow passages and decreases the sampling density in wide-open regions. We tested the new planner on rigid-body and articulated robots in 2-D and 3-D environments. Experimental results show that WIS improves the planner's performance for path planning problems with narrow passages.\",\n \"Title: Predicting experimental quantities in protein folding kinetics using stochastic roadmap simulation\\nYear: 2006\\n\\nAbstract: This paper presents a new method for studying protein folding kinetics. It uses the recently introduced Stochastic Roadmap Simulation (SRS) method to estimate the transition state ensemble (TSE) and predict the rates and Φ-values for protein folding. The new method was tested on 16 proteins. Comparison with experimental data shows that it estimates the TSE much more accurately than an existing method based on dynamic programming. This leads to better folding-rate predictions. The results on Φ-value predictions are mixed, possibly due to the simple energy model used in the tests. This is the first time that results obtained from SRS have been compared against a substantial amount of experimental data. The success further validates the SRS method and indicates its potential as a general tool for studying protein folding kinetics.\",\n \"Title: Stochastic roadmap simulation: an efficient representation and algorithm for analyzing molecular motion\\nYear: 2002\\n\\nAbstract: Classic molecular motion simulation techniques, such as Monte Carlo (MC) simulation, generate motion pathways one at a time and spend most of their time in the local minima of the energy landscape defined over a molecular conformation space. Their high computational cost prevents them from being used to compute ensemble properties (properties requiring the analysis of many pathways). This paper introduces stochastic roadmap simulation (SRS) as a new computational approach for exploring the kinetics of molecular motion by simultaneously examining multiple pathways. These pathways are compactly encoded in a graph, which is constructed by sampling a molecular conformation space at random. This computation, which does not trace any particular pathway explicitly, circumvents the local-minima problem. Each edge in the graph represents a potential transition of the molecule and is associated with a probability indicating the likelihood of this transition. By viewing the graph as a Markov chain, ensemble properties can be efficiently computed over the entire molecular energy landscape. Furthermore, SRS converges to the same distribution as MC simulation. SRS is applied to two biological problems: computing the probability of folding, an important order parameter that measures the \\\"kinetic distance\\\" of a protein's conformation from its native state; and estimating the expected time to escape from a ligand-protein binding site. Comparison with MC simulations on protein folding shows that SRS produces arguably more accurate results, while reducing computation time by several orders of magnitude. Computational studies on ligand-protein binding also demonstrate SRS as a promising approach to study ligand-protein interactions.\",\n \"Title: Adaptive Quantization and Density Estimation in Silicon\\nYear: 2002\\n\\nAbstract: We present the bump mixture model, a statistical model for analog data where the probabilistic semantics, inference, and learning rules derive from low-level transistor behavior. The bump mixture model relies on translinear circuits to perform probabilistic infer- ence, and floating-gate devices to perform adaptation. This system is low power, asynchronous, and fully parallel, and supports vari- ous on-chip learning algorithms. In addition, the mixture model can perform several tasks such as probability estimation, vector quanti- zation, classification, and clustering. We tested a fabricated system on clustering, quantization, and classification of handwritten digits and show performance comparable to the E-M algorithm on mix- tures of Gaussians.\",\n \"Title: Integrated perception and planning in the continuous space: A POMDP approach\\nYear: 2013\\n\\nAbstract: The partially observable Markov decision process (POMDP) provides a principled mathematical model for integrating perception and planning, a major challenge in robotics. While there are efficient algorithms for moderately large discrete POMDPs, continuous models are often more natural for robotic tasks, and currently there are no practical algorithms that handle continuous POMDPs at an interesting scale. This paper presents an algorithm for continuous-state, continuous-observation POMDPs. We provide experimental results demonstrating its potential in robot planning and learning under uncertainty and a theoretical analysis of its performance. A direct benefit of the algorithm is to simplify model construction.\",\n \"Title: Probabilistic Approximations of Signaling Pathway Dynamics\\nYear: 2009\\n\\nAbstract: Systems of ordinary differential equations (ODEs) are often used to model the dynamics of complex biological pathways. We construct a discrete state model as a probabilistic approximation of the ODE dynamics by discretizing the value space and the time domain. We then sample a representative set of trajectories and exploit the discretization and the structure of the signaling pathway to encode these trajectories compactly as a dynamic Bayesian network. As a result, many interesting pathway properties can be analyzed efficiently through standard Bayesian inference techniques. We have tested our method on a model of EGF-NGF signaling pathway [1] and the results are very promising in terms of both accuracy and efficiency.\",\n \"Title: A Fast Filter for Obstructed Nearest Neighbor Queries\\nYear: 2004\\n\\nAbstract: In this paper, we study the Obstructed Nearest Neighbor (ONN) problem: given a set of points and a set of polygonal obstacles in two dimensions, find the k nearest neighbors to a query point according to the length of the shortest obstacle-avoiding path between two points. ONN query is useful both as a stand-alone tool in geographical information systems and as a primitive for spatial data analysis such as clustering and classification in the presence of obstacles. We propose an efficient ONN algorithm that processes only the data points and obstacles relevant to the query in an incremental way and thus filters out a large number of points and obstacles. Experiments on spatial data sets show the algorithm scales well with respect to the input data size and the number of nearest neighbors requested.\",\n \"Title: Stochastic Conformational Roadmaps for Computing Ensemble Properties of Molecular Motion.\\nYear: 2002\\n\\nAbstract: A key intuition behind probabilistic roadmap planners for motion planning is that many collision-free paths potentially exist between two given robot configurations. Hence the connectivity of a robot's free space can be captured effectively by a network of randomly sampled configurations. In this paper, a similar intuition is exploited to preprocess molecular motion pathways and efficiently compute their ensemble properties, i.e., properties characterizing the average behavior of many pathways. We construct a directed graph, called stochastic conformational roadmap, whose nodes are randomly sampled molecule conformations. A roadmap compactly encodes many molecular motion pathways. Ensemble properties are computed by viewing the roadmap as a Markov chain. A salient feature of this new approach is that it examines all the paths in the roadmap simultaneously, rather than one at a time as classic methods such as Monte Carlo (MC) simulation would do. It also avoids the local-minima problem encountered by the classic methods. Tests of the approach on two important biological problems show that it produces more accurate results and achieves several orders of magnitude reduction in computation time, compared with MC simulation.\",\n \"Title: Composing Globally Consistent Pathway Parameter Estimates Through Belief Propagation\\nYear: 2007\\n\\nAbstract: Parameter estimation of large bio-pathway models is an important and difficult problem. To reduce the prohibitive computational cost, one approach is to decompose a large model into components and estimate their parameters separately. However, the decomposed components often share common parts that may have conflicting parameter estimates, as they are computed independently within each component. In this paper, we propose to use a probabilistic inference technique called belief propagation to reconcile these independent estimates in a principled manner and compute new estimates that are globally consistent and fit well with data. An important advantage of our approach in practice is that it naturally handles incomplete or noisy data. Preliminary results based on synthetic data show promising performance in terms of both accuracy and efficiency.\",\n \"Title: Disconnection Proofs For Motion Planning\\nYear: 2001\\n\\nAbstract: Probabilistic road-map (PRM) planners have shown great promise in attacking previously infeasible motion planning problems with many degrees of freedom. Yet when such a planner Jails to find a path, it is not clear that no path exists, or that the planner simply did not sample adequately or intelligently the free part of the configuration space. We propose to attack the motion planning problem front the other end, focusing on disconnection proofs, or proofs showing that there exists no solution to the posed motion planning problem. Just as PRM planners avoid generating a complete description of the configuration space, our disconnection provers search for certain special classes of proofs that are compact and easy to find when the motion planning problem is 'obviously impossible,' avoiding complex geometric and combinatorial calculations. We demonstrate such a prover in action for a simple, ' yet still realistic, motion planning problem. When it fails. the prover suggests key milestones, or configurations of the robot that can then be passed on and used by a PRM planner Thus by hitting the motion planning problem from both ends, we hope to resolve the existence of a path, except in truly delicate border-line situations.\",\n \"Title: Probabilistic approximations of ODEs based bio-pathway dynamics\\nYear: 2011\\n\\nAbstract: Bio-chemical networks are often modeled as systems of ordinary differential equations (ODEs). Such systems will not admit closed form solutions and hence numerical simulations will have to be used to perform analyses. However, the number of simulations required to carry out tasks such as parameter estimation can become very large. To get around this, we propose a discrete probabilistic approximation of the ODEs dynamics. We do so by discretizing the value and the time domain and assuming a distribution of initial states w.r.t. the discretization. Then we sample a representative set of initial states according to the assumed initial distribution and generate a corresponding set of trajectories through numerical simulations. Finally, using the structure of the signaling pathway we encode these trajectories compactly as a dynamic Bayesian network. This approximation of the signaling pathway dynamics has several advantages. First, the discretized nature of the approximation helps to bridge the gap between the accuracy of the results obtained by ODE simulation and the limited precision of experimental data used for model construction and verification. Second and more importantly, many interesting pathway properties can be analyzed efficiently through standard Bayesian inference techniques instead of resorting to a large number of ODE simulations. We have tested our method on ODE models of the EGF-NGF signaling pathway [1] and the segmentation clock pathway [2]. The results are very promising in terms of accuracy and efficiency.\",\n \"Title: CAPIR: Collaborative Action Planning with Intention Recognition\\nYear: 2011\\n\\nAbstract: We apply decision theoretic techniques to construct non-player characters that are able to assist a human player in collaborative games. The method is based on solving Markov decision processes, which can be difficult when the game state is described by many variables. To scale to more complex games, the method allows decomposition of a game task into subtasks, each of which can be modelled by a Markov decision process. Intention recognition is used to infer the subtask that the human is currently performing, allowing the helper to assist the human in performing the correct task. Experiments show that the method can be effective, giving near-human level performance in helping a human in a collaborative game.\",\n \"Title: On the Probabilistic Foundations of Probabilistic Roadmap Planning\\nYear: 2006\\n\\nAbstract: Why is probabilistic roadmap (PRM) planning probabilistic? How does the probability measure used for sampling a robot's configuration space affect the performance of a PRM planner? These questions have received little attention so far. This paper tries to fill this gap, with the intent to identify promising directions to improve future planners. It introduces the probabilistic foundations of PRM planning and examines previous work in this context. It shows that the success of PRM planning depends mainly and critically on favorable \\\"visibility\\\" properties of a robot's configuration space. A promising direction for speeding up PRM planners is to infer partial knowledge on such properties from both workspace geometry and information gathered during roadmap construction, and to use this knowledge to adapt the probability measure for sampling. This paper also shows that the choice of the sampling source, pseudo-random or deterministic, has small impact on a PRM planner's performance, compared to that of the sampling measure. These conclusions are supported by both theoretical and empirical results.\",\n \"Title: Capturing the Connectivity of High-Dimensional Geometric Spaces by Parallelizable Random Sampling Techniques\\nYear: 1998\\n\\nAbstract: Finding paths in high-dimensional gemetric spaces is a provably hard problem. Recently, a general randomized planning scheme has emerged as an effective approach to solve this problem. In this scheme the planner samples the space at random and build a network of simple paths, called a probabilistic roadmap. This paper describes a basic probabilistic roadmap planner, which is easily parallelizable, and provides a formal analysis that explains its empirical success when the space satisfies two geometric properties called epsilon-goodness and expansiveness.\",\n \"Title: Incremental signaling pathway modeling by data integration\\nYear: 2010\\n\\nAbstract: Constructing quantitative dynamic models of signaling pathways is an important task for computational systems biology Pathway model construction is often an inherently incremental process, with new pathway players and interactions continuously being discovered and additional experimental data being generated Here we focus on the problem of performing model parameter estimation incrementally by integrating new experimental data into an existing model A probabilistic graphical model known as the factor graph is used to represent pathway parameter estimates By exploiting the network structure of a pathway, a factor graph compactly encodes many parameter estimates of varying quality as a probability distribution When new data arrives, the parameter estimates are refined efficiently by applying a probabilistic inference algorithm known as belief propagation to the factor graph A key advantage of our approach is that the factor graph model contains enough information about the old data, and uses only new data to refine the parameter estimates without requiring explicit access to the old data To test this approach, we applied it to the Akt-MAPK pathways, which regulate the apoptotic process and are among the most actively studied signaling pathways The results show that our new approach can obtain parameter estimates that fit the data well and refine them incrementally when new data arrives.\",\n \"Title: pFlexAna: detecting conformational changes in remotely related proteins.\\nYear: 2008\\n\\nAbstract: The pFlexAna (protein flexibility analyzer) web server detects and displays conformational changes in remotely related proteins, without relying on sequence homology. To do so, it first applies a reliable statistical test to align core protein fragments that are structurally similar and then clusters these aligned fragment pairs into super-alignments, according to the similarity of geometric transformations that align them. The result is that the dominant conformational changes occur between the clusters, while the smaller conformational changes occur within a cluster. pFlexAna is available at http://bigbird.comp.nus.edu.sg/pfa2/.\",\n \"Title: Multi-Level Free-Space Dilation For Sampling Narrow Passages In Prm Planning\\nYear: 2006\\n\\nAbstract: Free-space dilation is an effective approach for narrow passage sampling, a well-recognized difficulty in probabilistic roadmap (PRM) planning. Key to this approach are methods for dilating the free space and for determining the amount of dilation needed. This paper presents a new method of dilation by shrinking the geometric models of robots and obstacles. Compared with existing work, the new method is more efficient in both running time and memory usage. It is also integrated with collision checking, a key operation in PRM planning. The efficiency of the dilation method enables a new PRM planner which quickly constructs a series of dilated free spaces and automatically determine the amount of dilation needed. Experiments show that both the dilation method and the planner work well in complex geometric environments. In particular, the planner reliably solved the most difficult version of the alpha puzzle, a benchmark test for PRM planners.\",\n \"Title: The creation of a music-driven digital violinist\\nYear: 2004\\n\\nAbstract: This paper describes an initial attempt on a music-driven digital violinist (MDV) system, which automatically generates animation of a violinist based on violin music. MDV first analyzes the input audio signal and transcribes it into music notes. Next it uses the notes to synthesize the animated video of a violinist. Tests on the prototype system show that it achieves adequate visual realism and near real-time performance.\",\n \"Title: Monte Carlo Bayesian Reinforcement Learning.\\nYear: 2012\\n\\nAbstract: Bayesian reinforcement learning (BRL) encodes prior knowledge of the world in a model and represents uncertainty in model parameters by maintaining a probability distribution over them. This paper presents Monte Carlo BRL (MC-BRL), a simple and general approach to BRL. MC-BRL samples a priori a finite set of hypotheses for the model parameter values and forms a discrete partially observable Markov decision process (POMDP) whose state space is a cross product of the state space for the reinforcement learning task and the sampled model parameter space. The POMDP does not require conjugate distributions for belief representation, as earlier works do, and can be solved relatively easily with point-based approximation algorithms. MC-BRL naturally handles both fully and partially observable worlds. Theoretical and experimental results show that the discrete POMDP approximates the underlying BRL task well with guaranteed performance.\",\n \"Title: Covering Number for Efficient Heuristic-based POMDP Planning.\\nYear: 2014\\n\\nAbstract: The difficulty of POMDP planning depends on the size of the search space involved. Heuristics are often used to reduce the search space size and improve computational efficiency; however, there are few theoretical bounds on their effectiveness. In this paper, we use the covering number to characterize the size of the search space reachable under heuristics and connect the complexity of POMDP planning to the effectiveness of heuristics. With insights from the theoretical analysis, we have developed a practical POMDP algorithm, Packing-Guided Value Iteration (PGVI). Empirically, PGVI is competitive with the state-of-the-art point-based POMDP algorithms on 65 small benchmark problems and outperforms them on 4 larger problems.\",\n \"Title: Neuronal avalanches and criticality: A dynamical model for homeostasis\\nYear: 2006\\n\\nAbstract: The dynamics of microelectrode local field potentials from cortical slice cultures shows critical behavior. A desirable feature of criticality is that information transmission is optimal in this state. We explore a biologically plausible neural net model that can dynamically converge on criticality and that can return to criticality if perturbed away from it. Our model assumes the presence of a preferred target firing rate, with dynamical adjustments of internodal connection strengths to approach this firing rate. We suggest that mechanisms for maintaining firing rate homeostasis may also maintain a neural system at criticality.\",\n \"Title: Bounded Uncertainty Roadmaps for Path Planning\\nYear: 2008\\n\\nAbstract: Motion planning under uncertainty is an important problem in robotics. Although probabilistic sampling is highly successful for motion planning of robots with many degrees of freedom, sampling-based algorithms typically ignore uncertainty during planning. We in- troduce the notion of a bounded uncertainty roadmap (BURM) and use it to extend sampling- based algorithms for planning under uncertainty in environment maps. The key idea of our approach is to evaluate uncertainty, represented by collision probability bounds, at multiple resolutions in different regions of the configuration space, depending on their relevance for finding a best path. Preliminary experimental results show that our approach is highly effec- tive: our BURM algorithm is at least 40 times faster than an algorithm that tries to evaluate collision probabilities exactly, and it is not much slower than classic probabilistic roadmap planning algorithms, which ignore uncertainty in environment maps.\",\n \"Title: Planning under Uncertainty for Robotic Tasks with Mixed Observability\\nYear: 2010\\n\\nAbstract: Partially observable Markov decision processes (POMDPs) provide a principled, general framework for robot motion planning in uncertain and dynamic environments. They have been applied to various robotic tasks. However, solving POMDPs exactly is computationally intractable. A major challenge is to scale up POMDP algorithms for complex robotic tasks. Robotic systems often have mixed observability : even when a robotâ聙聶s state is not fully observable, some components of the state may still be so. We use a factored model to represent separately the fully and partially observable components of a robotâ聙聶s state and derive a compact lower-dimensional representation of its belief space. This factored representation can be combined with any point-based algorithm to compute approximate POMDP solutions. Experimental results show that on standard test problems, our approach improves the performance of a leading point-based POMDP algorithm by many times.\",\n \"Title: A Computational And Experimental Study Of The Regulatory Mechanisms Of The Complement System\\nYear: 2011\\n\\nAbstract: The complement system is key to innate immunity and its activation is necessary for the clearance of bacteria and apoptotic cells. However, insufficient or excessive complement activation will lead to immune-related diseases. It is so far unknown how the complement activity is up- or down-regulated and what the associated pathophysiological mechanisms are. To quantitatively understand the modulatory mechanisms of the complement system, we built a computational model involving the enhancement and suppression mechanisms that regulate complement activity. Our model consists of a large system of Ordinary Differential Equations (ODEs) accompanied by a dynamic Bayesian network as a probabilistic approximation of the ODE dynamics. Applying Bayesian inference techniques, this approximation was used to perform parameter estimation and sensitivity analysis. Our combined computational and experimental study showed that the antimicrobial response is sensitive to changes in pH and calcium levels, which determines the strength of the crosstalk between CRP and L-ficolin. Our study also revealed differential regulatory effects of C4BP. While C4BP delays but does not decrease the classical complement activation, it attenuates but does not significantly delay the lectin pathway activation. We also found that the major inhibitory role of C4BP is to facilitate the decay of C3 convertase. In summary, the present work elucidates the regulatory mechanisms of the complement system and demonstrates how the bio-pathway machinery maintains the balance between activation and inhibition. The insights we have gained could contribute to the development of therapies targeting the complement system.\",\n \"Title: A hierarchical method for real-time distance computation among moving convex bodies\\nYear: 2000\\n\\nAbstract: This paper presents the Hierarchical Walk , or H-Walk algorithm, which maintains the distance between two moving convex bodies by exploiting both motion coherence and hierarchical representations. For convex polygons, we prove that H-Walk improves on the classic Lin–Canny and Dobkin–Kirkpatrick algorithms. We have implemented H-Walk for moving convex polyhedra in three dimensions. Experimental results indicate that, unlike previous incremental distance computation algorithms, H-Walk adapts well to variable coherence in the motion and provides consistent performance.\",\n \"Title: Motion planning under uncertainty for robotic tasks with long time horizons\\nYear: 2011\\n\\nAbstract: Motion planning with imperfect state information is a crucial capability for autonomous robots to operate reliably in uncertain and dynamic environments. Partially observable Markov decision processes (POMDPs) provide a principled general framework for planning under uncertainty. Using probabilistic sampling, point-based POMDP solvers have drastically improved the speed of POMDP planning, enabling us to handle moderately complex robotic tasks. However, robot motion planning tasks with long time horizons remains a severe obstacle for even the fastest point-based POMDP solvers today. This paper proposes Milestone Guided Sampling (MiGS), a new point-based POMDP solver, which exploits state space information to reduce effective planning horizons. MiGS samples a set of points, called milestones, from a robot芒聙聶s state space and constructs a simplified representation of the state space from the sampled milestones. It then uses this representation of the state space to guide sampling in the belief space and tries to capture the essential features of the belief space with a small number of sampled points. Preliminary results are very promising. We tested MiGS in simulation on several difficult POMDPs that model distinct robotic tasks with long time horizons in both 2-D and 3-D environments. These POMDPs are impossible to solve with the fastest point-based solvers today, but MiGS solved them in a few minutes.\",\n \"Title: What makes some POMDP problems easy to approximate?\\nYear: 2007\\n\\nAbstract: Point-based algorithms have been surprisingly successful in computing approx- imately optimal solutions for partially observable Markov decision processes (POMDPs) in high dimensional belief spaces. In this work, we seek to understand the belief-space properties that allow some POMDP problems to be approximated efficiently and thus help to explain the point-based algorithms' success often ob- served in the experiments. We show that an approximately optimal POMDP so- lution can be computed in time polynomial in the covering number of a reachable belief space, which is the subset of the belief space reachable from a given belief point. We also show that under the weaker condition of having a small covering number for an optimal reachable space, which is the subset of the belief space reachable under an optimal policy, computing an approximately optimal solution is NP-hard. However, given a suitable set of points that \\\"cover\\\" an optimal reach- able space well, an approximate solution can be computed in polynomial time. The covering number highlights several interesting properties that reduce the com- plexity of POMDP planning in practice, e.g., fully observed state variables, beliefs with sparse support, smooth beliefs, and circulant state-transition matrices.\",\n \"Title: The Bridge Test For Sampling Narrow Passages With Probabilistic Roadmap Planners\\nYear: 2003\\n\\nAbstract: Probabilistic roadmap (PRM) planners have been successful in path planning of robots with many degrees of freedom, but narrow passages in a robot's configuration space create significant difficulty for PRM planners. This paper presents a hybrid sampling strategy in the PRM framework for finding paths through narrow passages. A key ingredient of the new strategy is the bridge test, which boosts the sampling density inside narrow passages. The bridge test relies on simple tests of local geometry and can be implemented efficiently in high-dimensional configuration spaces. The strengths of the bridge test and uniform sampling complement each other naturally and are combined to generate the final hybrid sampling strategy. Our planner was tested on point robots and articulated robots in planar workspaces. Preliminary experiments show that the hybrid sampling strategy enables relatively small roadmaps to reliably capture the connectivity of configuration spaces with difficult narrow passages.\",\n \"Title: Partially Observable Markov Decision Process (POMDP) Technologies for Sign Language Based Human-Computer Interaction\\nYear: 2009\\n\\nAbstract: Sign language (SL) recognition modules in human-computer interaction systems need to be both fast and reliable. In cases where multiple sets of features are extracted from the SL data, the recognition system can speed up processing by taking only a subset of extracted features as its input. However, this should not be realised at the expense of a drop in recognition accuracy. By training different recognizers for different subsets of features, we can formulate the problem as the task of planning the sequence of recognizer actions to apply to SL data, while accounting for the trade-off between recognition speed and accuracy. Partially observable Markov decision processes (POMDPs) provide a principled mathematical framework for such planning problems. A POMDP explicitly models the probabilities of observing various outputs from the individual recognizers and thus maintains a probability distribution (or belief) over the set of possible SL input sentences. It then computes a policy that maps every belief to an action. This allows the system to select actions in real-time during online policy execution, adapting its behaviour according to the observations encountered. We illustrate the POMDP approach with a simple sentence recognition problem and show in experiments the advantages of this approach over \\\"fixed action\\\" systems that do not adapt their behaviour in real-time.\",\n \"Title: Using stochastic roadmap simulation to predict experimental quantities in protein folding kinetics: folding rates and phi-values.\\nYear: 2007\\n\\nAbstract: This paper presents a new method for studying protein folding kinetics. It uses the recently introduced Stochastic Roadmap Simulation (SRS) method to estimate the transition state ensemble (TSE) and predict the rates and the Phi-values for protein folding. The new method was tested on 16 proteins, whose rates and Phi-values have been determined experimentally. Comparison with experimental data shows that our method estimates the TSE much, more accurately than an existing method based on dynamic programming. This improvement leads to better folding-rate predictions. We also compute the mean first passage time of the unfolded states and show that the computed values correlate with experimentally determined folding rates. The results on Phi-value predictions are mixed, possibly due to the simple energy model used in the tests. This is the first time that results obtained from SRS have been compared against a substantial amount of experimental data. The results further validate the SRS method and indicate its potential as a general tool for studying protein folding kinetics.\",\n \"Title: Randomized Kinodynamic Motion Planning With Moving Obstacles\\nYear: 2002\\n\\nAbstract: A randomized motion planner is presented for robots that must avoid collision with moving obstacles under kinematic and dynamic constraints. This planner samples the robot's state x time space by picking control inputs at random and integrating the equations of motion. The result is a probabilistic roadmap, i.e., a collection of sampled state x time points, called milestones, connected by short admissible trajectories. The planner does not precompute the roadmap; instead, for each planning query, it generates a new roadmap to connect the input initial and goal state x time points. This paper shows that the probability that the planner fails to find a trajectory when one exists quickly goes to 0 as the number of milestones grows. The planner has been tested successfully in both simulated and real environments. In the latter case, a vision module estimates the obstacle motions just before planning, and the planner is then allocated a small amount of time to compute a trajectory. If a change in obstacle motion is detected while the robot executes the planned trajectory, the planner re-computes a trajectory on the fly.\",\n \"Title: Markov dynamic models for long-timescale protein motion.\\nYear: 2010\\n\\nAbstract: Molecular dynamics (MD) simulation is a well-established method for studying protein motion at the atomic scale. However, it is computationally intensive and generates massive amounts of data. One way of addressing the dual challenges of computation efficiency and data analysis is to construct simplified models of long-timescale protein motion from MD simulation data. In this direction, we propose to use Markov models with hidden states, in which the Markovian states represent potentially overlapping probabilistic distributions over protein conformations. We also propose a principled criterion for evaluating the quality of a model by its ability to predict long-timescale protein motions. Our method was tested on 2D synthetic energy landscapes and two extensively studied peptides, alanine dipeptide and the villin headpiece subdomain (HP-35 NleNle). One interesting finding is that although a widely accepted model of alanine dipeptide contains six states, a simpler model with only three states is equally good for predicting long-timescale motions. We also used the constructed Markov models to estimate important kinetic and dynamic quantities for protein folding, in particular, mean first-passage time. The results are consistent with available experimental measurements.\",\n \"Title: Digital violin tutor: an integrated system for beginning violin learners\\nYear: 2005\\n\\nAbstract: Prompt feedback is essential for beginning violin learners; however, most amateur learners can only meet with teachers and receive feedback once or twice a week. To help such learners, we have attempted an initial design of Digital Violin Tutor (DVT), an integrated system that provides the much-needed feedback when human teachers are not available. DVT combines violin audio transcription with visualization. Our transcription method is fast, accurate, and robust again noise for violin audio recorded in home environments. The visualization is designed to be intuitive and easily understandable by people with little music knowledge. The different visualization modalities--video, 2D fingerboard animation, 3D avatar animation--help learners to practice and learn more effectively. The entire system has been implemented with off-the-shelf hardware and shown to be practical in home environments. In our user study, the system has received very positive evaluation.\",\n \"Title: Exploration in Interactive Personalized Music Recommendation: A Reinforcement Learning Approach\\nYear: 2013\\n\\nAbstract: Current music recommender systems typically act in a greedy manner by recommending songs with the highest user ratings. Greedy recommendation, however, is suboptimal over the long term: it does not actively gather information on user preferences and fails to recommend novel songs that are potentially interesting. A successful recommender system must balance the needs to explore user preferences and to exploit this information for recommendation. This article presents a new approach to music recommendation by formulating this exploration-exploitation trade-off as a reinforcement learning task. To learn user preferences, it uses a Bayesian model that accounts for both audio content and the novelty of recommendations. A piecewise-linear approximation to the model and a variational inference algorithm help to speed up Bayesian inference. One additional benefit of our approach is a single unified model for both music recommendation and playlist generation. We demonstrate the strong potential of the proposed approach with simulation results and a user study.\",\n \"Title: Protein conformational flexibility analysis with noisy data.\\nYear: 2008\\n\\nAbstract: Protein conformational changes play a critical role in biological functions such as ligand-protein and protein-protein interactions. Due to the noise in structural data, determining salient conformational changes reliably and efficiently is a challenging problem. This paper presents an efficient algorithm for analyzing protein conformational changes, when the data is noisy. It applies a statistical flexibility test to all contiguous fragments of a protein and combines the information from these tests to compute a consensus flexibility measure for each residue of the protein. We tested the algorithm using data from the Protein Data Bank and the Macromolecular Movements Database. The results show that our algorithm can reliably detect different types of salient conformational changes, including well-known examples such as hinge and shear, as well as the flap motion of HIV-1 protease. The software implementing our algorithm is available at http://motion.comp.nus.edu.sg/projects/proflexana/ proflexana.html.\",\n \"Title: Stealth Tracking of an Unpredictable Target among Obstacles.\\nYear: 2004\\n\\nAbstract: This papers introduces the stealth tracking problem, in which a robot, equipped with visual sensors, tries to track a moving target among obstacles and, at the same time, remain hidden from the target. Obstacles impede both the tracker's motion and visibility, but on the other hand, provide hiding places for the tracker. Our proposed tracking algorithm uses only local information from the tracker's visual sensors and assumes no prior knowledge of target motion or a global map of the environment. It applies a local greedy strategy, and chooses the best move at each time step by minimizing the target's escape risk, subject to the stealth constraint. The algorithm is efficient, taking O(n) time at each step, where n is the complexity of the tracker's visibility region. Simulation experiments show that the algorithm performs well in difficult environments.\",\n \"Title: Characterization of structural variants with single molecule and hybrid sequencing approaches.\\nYear: 2014\\n\\nAbstract: Motivation: Structural variation is common in human and cancer genomes. High-throughput DNA sequencing has enabled genome-scale surveys of structural variation. However, the short reads produced by these technologies limit the study of complex variants, particularly those involving repetitive regions. Recent 'third-generation' sequencing technologies provide single-molecule templates and longer sequencing reads, but at the cost of higher per-nucleotide error rates. Results: We present MultiBreak-SV, an algorithm to detect structural variants (SVs) from single molecule sequencing data, paired read sequencing data, or a combination of sequencing data from different platforms. We demonstrate that combining low-coverage third-generation data from Pacific Biosciences (PacBio) with high-coverage paired read data is advantageous on simulated chromosomes. We apply MultiBreak-SV to PacBio data from four human fosmids and show that it detects known SVs with high sensitivity and specificity. Finally, we perform a whole-genome analysis on PacBio data from a complete hydatidiform mole cell line and predict 1002 high-probability SVs, over half of which are confirmed by an Illumina-based assembly.\",\n \"Title: Path planning in expansive configuration spaces\\nYear: 1997\\n\\nAbstract: We introduce the notion of expansiveness to characterize a family of robot configuration spaces whose connectivity can be effectively captured by a roadmap of randomly-sampled milestones. The analysis of expansive configuration spaces has inspired us to develop a new randomized planning algorithm. This algorithm tries to sample only the portion of the configuration space that is relevant to the current query, avoiding the cost of precomputing a roadmap for the entire configuration space. Thus, it is well-suited for problems where a single query is submitted for a given environment. The algorithm has been implemented and successfully applied to complex assembly maintainability problems from the automotive industry\",\n \"Title: Adaptively combining multiple sampling strategies for probabilistic roadmap planning\\nYear: 2004\\n\\nAbstract: Several sophisticated sampling strategies have been proposed recently to address the narrow passage problem for probabilistic roadmap (PRM) planning. They all have unique strengths and weaknesses in different environments, but in general, none seems sufficient on its own. In this paper, we present a new approach that adaptively combines multiple sampling strategies for PRM planning. Using this approach, we describe an adaptive hybrid sampling (AHS) strategy using two component samplers: the bridge test, a specialized sampler for narrow passages, and the uniform sampler. We tested the AHS strategy on robots with two to eight degrees of freedom. These preliminary tests show that the AHS strategy achieves consistently good performance, compared with fixed-weight hybrid sampling strategies.\",\n \"Title: Hybrid PRM Sampling with a Cost-Sensitive Adaptive Strategy\\nYear: 2005\\n\\nAbstract: A number of advanced sampling strategies have been proposed in recent years to address the narrow passage problem for probabilistic roadmap (PRM) planning. These sampling strategies all have unique strengths, but none of them solves the problem completely. In this paper, we present a general and systematic approach for adaptively combining multiple sampling strategies so that their individual strengths are preserved. We have performed experiments with this approach on robots with up to 12 degrees of freedom in complex 3-D environments. Experiments show that although the performance of individual sampling strategies varies across different environments, the adaptive hybrid sampling strategies constructed with this approach perform consistently well in all environments. Further, we show that, under reasonable assumptions, the adaptive strategies are provably competitive against all individual strategies used.\",\n \"Title: Kinodynamic motion planning amidst moving obstacles\\nYear: 2000\\n\\nAbstract: This paper presents a randomized motion planner for kinodynamic asteroid avoidance problems, in which a robot must avoid collision with moving obstacles under kinematic, dynamic constraints and reach a specified goal state. Inspired by probabilistic-roadmap (PRM) techniques, the planner samples the state x time space of a robot by picking control inputs at random in order to compute a roadmap that captures the connectivity of the space. However, the planner does not precompute a roadmap as most PRM planners do. Instead, for each planning query, it generates, on the fly, a small roadmap that connects the given initial and goal state. In contrast to PRM planners, the roadmap computed by our algorithm is a directed graph oriented along the time axis of the space. To verify the planner's effectiveness in practice, we tested it both in simulated environments containing many moving obstacles and on a real robot under strict dynamic constraints. The efficiency of the planner makes it possible for a robot to respond to a changing environment without knowing the motion of moving obstacles well in advance\",\n \"Title: A greedy strategy for tracking a locally predictable target among obstacles\\nYear: 2006\\n\\nAbstract: Target tracking among obstacles is an interesting class of motion planning problems that combine the usual motion constraints with robot sensors' visibility constraints. In this paper, we introduce the notion of vantage time and use it to formulate a risk function that evaluates the robot's advantage in maintaining the visibility constraint against the target. Local minimization of the risk function leads to a greedy tracking strategy. We also use simple velocity prediction on the target to further improve tracking performance. We compared our new strategy with earlier work in extensive simulation experiments and obtained much improved results. I. INTRODUCTION The target tracking problem considers motion strategies for an autonomous mobile robot to track a moving target among obstacles, i.e., to keep the target within the robot sensor's visibility region. Target tracking has many applications. In home care settings, a tracking robot can follow elderly people around and alert caregivers of emergencies. In security and surveillance systems, tracking strategies enable mobile sensors to monitor moving targets in cluttered environments. Target tracking is an especially interesting class of motion planning problems. Just as in classic motion planning (7), we must consider motion constraints resulting from both obstacles in the environment and the robot's mechanical limitations. In particular, the robot must not collide with obstacles. Target tracking has the additional visibility constraints due to sensor limitations, e.g., obstacles blocking the view of the robot's camera. The robot must move in such a way that the target remains visible at all times. Both motion constraints and visibility constraints play important roles in target tracking. Inspired by earlier work (5), we propose a greedy strategy for target tracking. It uses the robot's sensor to acquire local information on the target and the environment, and use this information to compute the robot's motion at each step. Thus, it does not need ap rioriknowledge of the environment or localization with respect to (w.r.t.) a global map. The key element of the greedy strategy is a local function ϕ that gives a combined estimate of the immediate risk of losing the target and the future risk. Our definition of ϕ is based on two important considerations: • Vantage time, which is a combined estimate of the robot's ability to maneuver against the target in both the current and future time. • The target's instantaneous velocity, which can be esti- mated locally, indicates the target's future movement. We show that by leveraging these two considerations, our new strategy achieves significant improvement in performance over the earlier strategy presented in (5). In the following, after a brief review of related work (Section II), we state the target tracking problem formally (Section III) and present our solution (Section IV). We have implemented the new tracking strategy and compared it with an existing one in simulated environments. The simulation results are shown in Section V. Finally, we conclude with some remarks on future research directions (Section VI).\",\n \"Title: Adaptive informative path planning in metric spaces\\nYear: 2014\\n\\nAbstract: AbstractIn contrast to classic geometric motion planning, informative path planning IPP seeks a path for a robot to sense the world and gain information. In adaptive IPP, the robot chooses the next sensing location conditioned on all information acquired so far, and the robot's goal is to minimize the travel cost required for identifying a true hypothesis. Adaptive IPP is NP-hard, because the robot must trade-off information gain and travel cost optimally. In this paper we present Recursive Adaptive Identification RAId, a new polynomial-time approximation algorithm for adaptive IPP. We prove a polylogarithmic approximation bound when the robot travels in a metric space. Furthermore, our experiments suggest that RAId is practical and provides good approximate solutions for two distinct robot planning tasks. Although RAId is designed primarily for noiseless observations, a simple extension allows it to handle some tasks with noisy observations.\",\n \"Title: Learning Dynamic Robot-to-Human Object Handover from Human Feedback\\nYear: 2015\\n\\nAbstract: Object handover is a basic, but essential capability for robots interacting with humans in many applications, e.g., caring for the elderly and assisting workers in manufacturing workshops. It appears deceptively simple, as humans perform object handover almost flawlessly. The success of humans, however, belies the complexity of object handover as collaborative physical interaction between two agents with limited communication. This paper presents a learning algorithm for dynamic object handover, for example, when a robot hands over water bottles to marathon runners passing by the water station. We formulate the problem as contextual policy search, in which the robot learns object handover by interacting with the human. A key challenge here is to learn the latent reward of the handover task under noisy human feedback. Preliminary experiments show that the robot learns to hand over a water bottle naturally and that it adapts to the dynamics of human motion. One challenge for the future is to combine the model-free learning algorithm with a model-based planning approach and enable the robot to adapt over human preferences and object characteristics, such as shape, weight, and surface texture.\",\n \"Title: Intention-aware online POMDP planning for autonomous driving in a crowd\\nYear: 2015\\n\\nAbstract: This paper presents an intention-aware online planning approach for autonomous driving amid many pedestrians. To drive near pedestrians safely, efficiently, and smoothly, autonomous vehicles must estimate unknown pedestrian intentions and hedge against the uncertainty in intention estimates in order to choose actions that are effective and robust. A key feature of our approach is to use the partially observable Markov decision process (POMDP) for systematic, robust decision making under uncertainty. Although there are concerns about the potentially high computational complexity of POMDP planning, experiments show that our POMDP-based planner runs in near real time, at 3 Hz, on a robot golf cart in a complex, dynamic environment. This indicates that POMDP planning is improving fast in computational efficiency and becoming increasingly practical as a tool for robot planning under uncertainty.\",\n \"Title: PLEASE: Palm Leaf Search for POMDPs with Large Observation Spaces\\nYear: 2015\\n\\nAbstract: Trial-based asynchronous value iteration algorithms for large Partially Observable Markov Decision Processes (POMDPs), such as HSVI2, FSVI and SARSOP, have made impressive progress in the past decade. In the forward exploration phase of these algorithms, only the outcome that has the highest potential impact is searched. This paper provides a novel approach, called Palm LEAf SEarch (PLEASE), which allows the selection of more than one outcome when their potential impacts are close to the highest one. Compared with existing trial-based algorithms, PLEASE can save considerable time to propagate the bound improvements of beliefs in deep levels of the search tree to the root belief because of fewer point-based value backups. Experiments show that PLEASE scales up SARSOP, one of the fastest algorithms, by orders of magnitude on some POMDP tasks with large observation spaces.\",\n \"Title: Synthetical Benchmarking of Service Robots: A First Effort on Domestic Mobile Platforms.\\nYear: 2015\\n\\nAbstract: Most of existing benchmarking tools for service robots are basically qualitative, in which a robot's performance on a task is evaluated based on completion/incompletion of actions contained in the task. In the effort reported in this paper, we tried to implement a synthetical benchmarking system on domestic mobile platforms. Synthetical benchmarking consists of both qualitative and quantitative aspects, such as task completion, accuracy of task completions and efficiency of task completions, about performance of a robot. The system includes a set of algorithms for collecting, recording and analyzing measurement data from a MoCap system. It was used as the evaluator in a competition called the BSR challenge, in which 10 teams participated, at RoboCup 2015. The paper presents our motivations behind synthetical benchmarking, the design considerations on the synthetical benchmarking system, the realization of the competition as a comparative study on performance evaluation of domestic mobile platforms, and an analysis of the teams' performance.\",\n \"Title: Adaptive Stochastic Optimization: From Sets to Paths\\nYear: 2015\\n\\nAbstract: Adaptive stochastic optimization (ASO) optimizes an objective function adaptively under uncertainty. It plays a crucial role in planning and learning under uncertainty, but is, unfortunately, computationally intractable in general. This paper introduces two conditions on the objective function, the marginal likelihood rate bound and the marginal likelihood bound, which, together with pointwise submodularity, enable efficient approximate solution of ASO. Several interesting classes of functions satisfy these conditions naturally, e.g., the version space reduction function for hypothesis learning. We describe Recursive Adaptive Coverage, a new ASO algorithm that exploits these conditions, and apply the algorithm to two robot planning tasks under uncertainty. In contrast to the earlier submodular optimization approach, our algorithm applies to ASO over both sets and paths.\",\n \"Title: DESPOT: Online POMDP Planning with Regularization.\\nYear: 2017\\n\\nAbstract: The partially observable Markov decision process (POMDP) provides a principled general framework for planning under uncertainty, but solving POMDPs optimally is computationally intractable, due to the \\\"curse of dimensionality\\\" and the \\\"curse of history\\\". To overcome these challenges, we introduce the Determinized Sparse Partially Observable Tree (DESPOT), a sparse approximation of the standard belief tree, for online planning under uncertainty. A DESPOT focuses online planning on a set of randomly sampled scenarios and compactly captures the \\\"execution\\\" of all policies under these scenarios. We show that the best policy obtained from a DESPOT is near-optimal, with a regret bound that depends on the representation size of the optimal policy. Leveraging this result, we give an anytime online planning algorithm, which searches a DESPOT for a policy that optimizes a regularized objective function. Regularization balances the estimated value of a policy under the sampled scenarios and the policy size, thus avoiding overfitting. The algorithm demonstrates strong experimental results, compared with some of the best online POMDP algorithms available. It has also been incorporated into an autonomous driving system for real-time vehicle control. The source code for the algorithm is available online.\",\n \"Title: Human-Robot Mutual Adaptation in Shared Autonomy.\\nYear: 2017\\n\\nAbstract: Shared autonomy integrates user input with robot autonomy in order to control a robot and help the user to complete a task. Our work aims to improve the performance of such a human-robot team: the robot tries to guide the human towards an effective strategy, sometimes against the human's own preference, while still retaining his trust. We achieve this through a principled human-robot mutual adaptation formalism. We integrate a bounded-memory adaptation model of the human into a partially observable stochastic decision model, which enables the robot to adapt to an adaptable human. When the human is adaptable, the robot guides the human towards a good strategy, maybe unknown to the human in advance. When the human is stubborn and not adaptable, the robot complies with the human's preference in order to retain their trust. In the shared autonomy setting, unlike many other common human-robot collaboration settings, only the robot actions can change the physical state of the world, and the human and robot goals are not fully observable. We address these challenges and show in a human subject experiment that the proposed mutual adaptation formalism improves human-robot team performance, while retaining a high level of user trust in the robot, compared to the common approach of having the robot strictly following participants' preference.\",\n \"Title: Factored Contextual Policy Search with Bayesian Optimization.\\nYear: 2016\\n\\nAbstract: Scarce data is a major challenge to scaling robot learning to truly complex tasks, as we need to generalize locally learned policies over different Bayesian optimization approaches to contextual policy search (CPS) offer data-efficient policy learning that generalize over a context space. We propose to improve data- efficiency by factoring typically considered contexts into two components: target- type contexts that correspond to a desired outcome of the learned behavior, e.g. target position for throwing a ball; and environment type contexts that correspond to some state of the environment, e.g. initial ball position or wind speed. Our key observation is that experience can be directly generalized over target-type contexts. Based on that we introduce Factored Contextual Policy Search with Bayesian Optimization for both passive and active learning settings. Preliminary results show faster policy generalization on a simulated toy problem.\",\n \"Title: Robots in Harmony with Humans.\\nYear: 2016\\n\\nAbstract: In early days, robots often occupied tightly controlled environments, for example, factory floors, designed to segregate robots and humans for safety. Today robots live with humans, providing a variety of services at homes, in workplaces, or on the road. To become effective and trustworthy collaborators, robots must understand human intentions and act accordingly in response. One core challenge here is the inherent uncertainty in understanding intentions, as a result of the complexity and diversity of human behaviours. Robots must hedge against such uncertainties to achieve robust performance and sometimes actively elicit information in order to reduce uncertainty and ascertain human intentions. Our recent work explores planning and learning under uncertainty for human-robot interactive or collaborative tasks. It covers mathematical models for human intentions, planning algorithms that connect robot perception with decision making, and learning algorithms that enable robots to adapt to human preferences. The work, I hope, will spur greater interest towards principled approaches that integrate perception, planning, and learning for fluid human-robot collaboration.\",\n \"Title: Supermodular Mean Squared Error Minimization For Sensor Scheduling In Optimal Kalman Filtering\\nYear: 2017\\n\\nAbstract: We consider the problem of scheduling a set of sensors to observe the state of a discrete-time linear system subject to a limited energy budget. Our goal is to devise a sensor schedule that minimizes the mean squared error (MSE) of an optimal estimator (i.e., the Kalman Filter). Both the minimum-MSE and the minimum-cardinality optimal sensor scheduling problems are inherently combinatorial, and computationally intractable. We remedy the combinatorial complexity by using a greedy heuristic; the greedy heuristic is guaranteed to return near-optimal solutions when minimizing supermodular objectives. While it is known that the MSE is not supermodular (with counterexamples available in literature), we provide conditions on the prior information matrix and on the observation matrix under which supermodularity holds. More specifically, we require the prior information matrix to be a strictly-diagonally-dominant M-matrix (plus an extra technical requirement on its inverse). Empirical results confirm that random M-matrices lead to supermodular problems, while this is not the case for generic prior information matrices. M- matrices naturally arise in estimation problems over networks and we provide a practical application of our findings to an energy-constrained multi robot localization problem.\",\n \"Title: Mathematical Models of Adaptation in Human-Robot Collaboration.\\nYear: 2017\\n\\nAbstract: A robot operating in isolation needs to reason over the uncertainty in its model of the world and adapt its own actions to account for this uncertainty. Similarly, a robot interacting with people needs to reason over its uncertainty over the human internal state, as well as over how this state may change, as humans adapt to the robot. This paper summarizes our own work in this area, which depicts the different ways that probabilistic planning and game-theoretic algorithms can enable such reasoning in robotic systems that collaborate with people. We start with a general formulation of the problem as a two-player game with incomplete information. We then articulate the different assumptions within this general formulation, and we explain how these lead to exciting and diverse robot behaviors in real-time interactions with actual human subjects, in a variety of manufacturing, personal robotics and assistive care settings.\",\n \"Title: Grounding Spatio-Semantic Referring Expressions for Human-Robot Interaction.\\nYear: 2017\\n\\nAbstract: The human language is one of the most natural interfaces for humans to interact with robots. This paper presents a robot system that retrieves everyday objects with unconstrained natural language descriptions. A core issue for the system is semantic and spatial grounding, which is to infer objects and their spatial relationships from images and natural language expressions. We introduce a two-stage neural-network grounding pipeline that maps natural language referring expressions directly to objects in the images. The first stage uses visual descriptions in the referring expressions to generate a candidate set of relevant objects. The second stage examines all pairwise relationships between the candidates and predicts the most likely referred object according to the spatial descriptions in the referring expressions. A key feature of our system is that by leveraging a large dataset of images labeled with text descriptions, it allows unrestricted object types and natural language referring expressions. Preliminary results indicate that our system outperforms a near state-of-the-art object comprehension system on standard benchmark datasets. We also present a robot system that follows voice commands to pick and place previously unseen objects.\",\n \"Title: Shortest Path Under Uncertainty: Exploration Versus Exploitation\\nYear: 2017\\n\\nAbstract: In the Canadian Traveler Problem (CTP), a traveler seeks a shortest path to a destination through a road network, but unknown to the traveler, some roads may be blocked. This paper studies the Bayesian CTP (BCTP), in which road states are correlated with known prior probabilities and the traveler can infer the states of an unseen road from past observations of other correlated roads. As generalized shortest-path problems, CTP and BCTP have important practical applications. We show that BCTP is NP-complete and give a polynomial-time approximation algorithm, Hedged Shortest Path under Determinization (HSPD), which approximates an optimal solution with a polylogarithmic factor. Preliminary experiments show promising results. HSPD outperforms a widely used greedy algorithm and a state-of-the-art UCT-based search algorithm for CTP, especially when significant exploration is required.\",\n \"Title: Intention-Net: Integrating Planning and Deep Learning for Goal-Directed Autonomous Navigation.\\nYear: 2017\\n\\nAbstract: How can a delivery robot navigate reliably to a destination in a new office building, with minimal prior information? To tackle this challenge, this paper introduces a two-level hierarchical approach, which integrates model-free deep learning and model-based path planning. At the low level, a neural-network motion controller, called the intention-net, is trained end-to-end to provide robust local navigation. The intention-net maps images from a single monocular camera and directly to robot controls. At the high level, a path planner uses a crude map, e.g., a 2-D floor plan, to compute a path from the robotu0027s current location to the goal. The planned path provides intentions to the intention-net. Preliminary experiments suggest that the learned motion controller is robust against perceptual uncertainty and by integrating with a path planner, it generalizes effectively to new environments and goals.\",\n \"Title: Human-robot mutual adaptation in collaborative tasks\\nYear: 2017\\n\\nAbstract: AbstractAdaptation is critical for effective team collaboration. This paper introduces a computational formalism for mutual adaptation between a robot and a human in collaborative tasks. We propose the Bounded-Memory Adaptation Model, which is a probabilistic finite-state controller that captures human adaptive behaviors under a bounded-memory assumption. We integrate the Bounded-Memory Adaptation Model into a probabilistic decision process, enabling the robot to guide adaptable participants towards a better way of completing the task. Human subject experiments suggest that the proposed formalism improves the effectiveness of human-robot teams in collaborative tasks, when compared with one-way adaptations of the robot to the human, while maintaining the human's trust in the robot.\",\n \"Title: Planning with Trust for Human-Robot Collaboration.\\nYear: 2018\\n\\nAbstract: Trust is essential for human-robot collaboration and user adoption of autonomous systems, such as robot assistants. This paper introduces a computational model which integrates trust into robot decision-making. Specifically, we learn from data a partially observable Markov decision process (POMDP) with human trust as a latent variable. The trust-POMDP model provides a principled approach for the robot to (i) infer the trust of a human teammate through interaction, (ii) reason about the effect of its own actions on human behaviors, and (iii) choose actions that maximize team performance over the long term. We validated the model through human subject experiments on a table-clearing task in simulation (201 participants) and with a real robot (20 participants). The results show that the trust-POMDP improves human-robot team performance in this task. They further suggest that maximizing trust in itself may not improve team performance.\",\n \"Title: Human Trust in Robot Capabilities across Tasks.\\nYear: 2018\\n\\nAbstract: In this work, we study how humans transfer or generalize trust in robot capabilities across tasks, even with limited observations. We present results from a human-subjects experiment using a real-world Fetch robot performing household tasks. In summary, we find that human trust generalization is influenced by perceived task similarity, difficulty, and robot performance.\",\n \"Title: Autonomous Driving among Many Pedestrians: Models and Algorithms.\\nYear: 2018\\n\\nAbstract: Driving among a dense crowd of pedestrians is a major challenge for autonomous vehicles. This paper presents a planning system for autonomous driving among many pedestrians. A key ingredient of our approach is a pedestrian motion prediction model that accounts for both a pedestrianu0027s global navigation intention and local interactions with the vehicle and other pedestrians. Unfortunately, the autonomous vehicle does not know the pedestrianu0027s intention a priori and requires a planning algorithm that hedges against the uncertainty in pedestrian intentions. Our planning system combines a POMDP algorithm with the pedestrian motion model and runs in near real time. Experiments show that it enables a robot vehicle to drive safely, efficiently, and smoothly among a crowd with a density of nearly one person per square meter.\",\n \"Title: Integrating Algorithmic Planning and Deep Learning for Partially Observable Navigation.\\nYear: 2018\\n\\nAbstract: We propose to take a novel approach to robot system design where each building block of a larger system is represented as a differentiable program, i.e. a deep neural network. This representation allows for integrating algorithmic planning and deep learning in a principled manner, and thus combine the benefits of model-free and model-based methods. We apply the proposed approach to a challenging partially observable robot navigation task. The robot must navigate to a goal in a previously unseen 3-D environment without knowing its initial location, and instead relying on a 2-D floor map and visual observations from an onboard camera. We introduce the Navigation Networks (NavNets) that encode state estimation, planning and acting in a single, end-to-end trainable recurrent neural network. In preliminary simulation experiments we successfully trained navigation networks to solve the challenging partially observable navigation task.\",\n \"Title: Particle Filter Networks with Application to Visual Localization.\\nYear: 2018\\n\\nAbstract: Particle filtering is a powerful approach to sequential state estimation and finds application in many domains, including robot localization, object tracking, etc. To apply particle filtering in practice, a critical challenge is to construct probabilistic system models, especially for systems with complex dynamics or rich sensory inputs such as camera images. This paper introduces the Particle Filter Network (PFnet), which encodes both a system model and a particle filter algorithm in a single neural network. The PF-net is fully differentiable and trained end-to-end from data. Instead of learning a generic system model, it learns a model optimized for the particle filter algorithm. We apply the PF-net to a visual localization task, in which a robot must localize in a rich 3-D world, using only a schematic 2-D floor map. In simulation experiments, PF-net consistently outperforms alternative learning architectures, as well as a traditional model-based method, under a variety of sensor inputs. Further, PF-net generalizes well to new, unseen environments.\",\n \"Title: PORCA: Modeling and Planning for Autonomous Driving Among Many Pedestrians.\\nYear: 2018\\n\\nAbstract: This letter presents a planning system for autonomous driving among many pedestrians. A key ingredient of our approach is Pedestrian Optimal Reciprocal Collision Avoidance, a pedestrian motion prediction model that accounts for both a pedestrian's global navigation intention and local interactions with the vehicle and other pedestrians. Unfortunately, the autonomous vehicle does not know the pedes...\",\n \"Title: Guided Exploration of Human Intentions for Human-Robot Interaction.\\nYear: 2018\\n\\nAbstract: Robot understanding of human intentions is essential for fluid human-robot interaction. Intentions, however, cannot be directly observed and must be inferred from behaviors. We learn a model of adaptive human behavior conditioned on the intention as a latent variable. We then embed the human behavior model into a principled probabilistic decision model, which enables the robot to (i) explore actively in order to infer human intentions and (ii) choose actions that maximize its performance. Furthermore, the robot learns from the demonstrated actions of human experts to further improve exploration. Preliminary experiments in simulation indicate that our approach, when applied to autonomous driving, improves the efficiency and safety of driving in common interactive driving scenarios.\",\n \"Title: Workspace-Based Connectivity Oracle: An Adaptive Sampling Strategy for PRM Planning\\nYear: 2006\\n\\nAbstract: This paper presents Workspace-based Connectivity Oracle (WCO), a dynamic sampling strategy for probabilistic roadmap planning. WCO uses both domain knowledge-specifically, workspace geometry-and sampling history to construct dynamic sampling distributions. It is composed of many component samplers, each based on a geometric feature of a robot. A component sampler updates its distribution, using information from the workspace geometry and the current state of the roachmap being constructed. These component samplers are combined through the adaptive hybrid sampling approach, based on their sampling histories. In the tests on rigid and articulated robots in 2-D and 3-D workspaces, WCO showed strong performance, compared with sampling strategies that use dynamic sampling or workspace information alone.\",\n \"Title: Importance sampling for online planning under uncertainty\\nYear: 2019\\n\\nAbstract: AbstractThe partially observable Markov decision process (POMDP) provides a principled general framework for robot planning under uncertainty. Leveraging the idea of Monte Carlo sampling, recent POMDP planning algorithms have scaled up to various challenging robotic tasks, including, real-time online planning for autonomous vehicles. To further improve online planning performance, this paper presents IS-DESPOT, which introduces importance sampling to DESPOT, a state-of-the-art sampling-based POMDP algorithm for planning under uncertainty. Importance sampling improves DESPOT’s performance when there are critical, but rare events, which are difficult to sample. We prove that IS-DESPOT retains the theoretical guarantee of DESPOT. We demonstrate empirically that importance sampling significantly improves the performance of online POMDP planning for suitable tasks. We also present a general method for learning the importance sampling distribution.\",\n \"Title: Robot Capability and Intention in Trust-Based Decisions Across Tasks\\nYear: 2019\\n\\nAbstract: In this paper, we present results from a human-subject study designed to explore two facets of human mental models of robots---inferred capability and intention---and their relationship to overall trust and eventual decisions. In particular, we examine delegation situations characterized by uncertainty, and explore how inferred capability and intention are applied across different tasks. We develop an online survey where human participants decide whether to delegate control to a simulated UAV agent. Our study shows that human estimations of robot capability and intent correlate strongly with overall self-reported trust. However, overall trust is not independently sufficient to determine whether a human will decide to trust (delegate) a given task to a robot. Instead, our study reveals that estimations of robot intention, capability, and overall trust are integrated when deciding to delegate. From a broader perspective, these results suggest that calibrating overall trust alone is insufficient; to make correct decisions, humans need (and use) multi-faceted mental models when collaborating with robots across multiple contexts.\",\n \"Title: Ab Initio Particle-Based Object Manipulation\\nYear: 2021\\n\\nAbstract: Particle-based Object Manipulation (PROMPT) is a new method for robot manipulation of novel objects, without prior object models or pre-training on a large object data set. The key element of PROMPT is a particle-based object representation, in which each particle represents a point in an object, the local geometric, physical, and other features of the point, and also its relation with other particles. The particle representation connects visual perception with robot control. Like data-driven methods, PROMPT infers the object representation online in real time from the visual sensor. Like model-based methods, PROMPT leverages the particle representation to reason about the object's geometry and dynamics, and choose suitable manipulation actions accordingly. PROMPT thus combines the strengths of model-based and data-driven methods. We show empirically that PROMPT successfully handles a variety of everyday objects, some of which are transparent. It handles various manipulation tasks, including grasping, pushing, etc.. Our experiments also show that PROMPT outperforms a state-of-the-art data-driven grasping method on everyday household objects, even though it does not use any offline training data. The code and a demonstration video are available online.\",\n \"Title: Magic: Learning Macro-Actions For Online Pomdp Planning\\nYear: 2021\\n\\nAbstract: The partially observable Markov decision process (POMDP) is a principled general framework for robot decision making under uncertainty, but POMDP planning suffers from high computational complexity, when long-term planning is required. While temporally-extended macro-actions help to cut down the effective planning horizon and significantly improve computational efficiency, how do we acquire good macroactions? This paper proposes Macro-Action Generator-Critic (MAGIC), which performs offline learning of macro-actions optimized for online POMDP planning. Specifically, MAGIC learns a macro-action generator end-to-end, using an online planner's performance as the feedback. During online planning, the generator generates on the fly situation-aware macro-actions conditioned on the robot's belief and the environment context. We evaluated MAGIC on several long-horizon planning tasks both in simulation and on a real robot. The experimental results show that the learned macro-actions offer significant benefits in online planning performance, compared with primitive actions and handcrafted macro-actions.\",\n \"Title: Invigorate: Interactive Visual Grounding And Grasping In Clutter\\nYear: 2021\\n\\nAbstract: This paper presents INVIGORATE, a robot system that interacts with human through natural language and grasps a specified object in clutter. The objects may occlude, obstruct, or even stack on top of one another. INVIGORATE embodies several challenges: (i) infer the target object among other occluding objects, from input language expressions and RGB images, (ii) infer object blocking relationships (OBRs) from the images, and (iii) synthesize a multi-step plan to ask questions that disambiguate the target object and to grasp it successfully. We train separate neural networks for object detection, for visual grounding, for question generation, and for OBR detection and grasping. They allow for unrestricted object categories and language expressions, subject to the training datasets. However, errors in visual perception and ambiguity in human languages are inevitable and negatively impact the robot's performance. To overcome these uncertainties, we build a partially observable Markov decision process (POMDP) that integrates the learned neural network modules. Through approximate POMDP planning, the robot tracks the history of observations and asks disambiguation questions in order to achieve a near-optimal sequence of actions that identify and grasp the target object. INVIGORATE combines the benefits of model-based POMDP planning and data-driven deep learning. Preliminary experiments with INVIGORATE on a Fetch robot show significant benefits of this integrated approach to object grasping in clutter with natural language interactions. A demonstration video is available online.(1)\",\n \"Title: Interactive Planning for Autonomous Urban Driving in Adversarial Scenarios 2021\\nYear: 2021\\n\\nAbstract: Autonomous urban driving among human-driven cars requires a holistic understanding of road rules, driver intents and driving styles. This is challenging as a short-term, single instance, driver intent of lane change may not correspond to their driving styles for a longer duration. This paper presents an interactive behavior planner which accounts for road context, short-term driver intent, and long-term driving style to infer beliefs over the latent states of surrounding vehicles. We use a specialized Partially Observable Markov Decision Process to provide risk-averse decisions. Specifically, we consider adversarial driving scenarios caused by irrational drivers to validate the robustness of our proposed interactive behavior planner in simulation as well as on a full-size selfdriving car. Our experimental results show that our algorithm enables safer and more travel time-efficient autonomous driving compared to baselines even in adversarial scenarios.\",\n \"Title: GAMMA: A General Agent Motion Model for Autonomous Driving\\nYear: 2022\\n\\nAbstract: This letter presents GAMMA, a general motion prediction model that enables large-scale real-time simulation and planning for autonomous driving. GAMMA models heterogeneous, interactive traffic agents that operate under diverse road conditions, with various geometric and kinematic constraints. GAMMA treats the prediction task as constrained optimization in traffic agents' velocity space. The objective is to optimize an agent's driving performance, while obeying all the constraints resulting from the agent's kinematics, collision avoidance with other agents, and the environmental context. Further, GAMMA explicitly conditions the prediction on human behavioral states as parameters of the optimization model, in order to account for versatile human behaviors. We evaluated GAMMA on a set of real-world benchmark datasets. The results show that GAMMA achieves high prediction accuracy on both homogeneous and heterogeneous traffic datasets, with sub-millisecond execution time. Further, the computational efficiency and the flexibility of GAMMA enable (i) simulation of mixed urban traffic at many locations worldwide and (ii) planning for autonomous driving in dense traffic with uncertain driver behaviors, both in real-time. The open-source code of GAMMA is available online.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":88,"string":"88"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":264,"string":"264"}}},{"rowIdx":265,"cells":{"question_id":{"kind":"string","value":"Zixiang Xiong"},"question":{"kind":"string","value":"Generate an abstract for the title \"Successive refinement for the Wyner-Ziv problem and layered code design\" using the following items: 1. Successive refinement \n2. Wyner-Ziv problem \n3. Layered code design \n4. Low-density parity check \n5. Dual symmetry."},"answer":{"kind":"string","value":"We examine successive refinement for the Wyner-Ziv problem described in a recent paper by Steinberg and Merhav, where the authors showed that if the side information for all stages is identical, then the jointly Gaussian source with squared error distortion measure is successively refinable. We first extend this result to the case where the difference between the source and the side information is Gaussian and independent of the side information. As a byproduct, we give an alternative proof that the Wyner-Ziv problem for these sources has no rate loss-a result that was recently shown by Pradhan et al. through invoking the duality between the Gaussian Wyner-Ziv problem and the Costa problem. We then perform layered Wyner-Ziv code design for this general type of source based on nested scalar quantization, bit-plane coding, and low-density parity check (LDPC) code-based Slepian-Wolf coding (source coding with side information). We show that density evolution can be used to analyze the Slepian-Wolf code performance, provided that certain symmetry conditions, which have been dubbed dual symmetry, are satisfied by the hypothetical channel between the source and the side information. We also show that the dual symmetry condition is indeed satisfied by the hypothetical channel in our Slepian-Wolf coding setup. This justifies the use of density evolution in our LDPC code-based Slepian-Wolf code design for Wyner-Ziv coding. For the jointly Gaussian source, our layered coder performs 1.29 to 3.45 dB from the Wyner-Ziv bound for rates ranging from 0.47 to 4.68 bits per sample. When the side information is Laplacian and the source equals the side information plus an independent Gaussian noise term, our layered coder performs 1.33 to 3.90 dB from the Wyner-Ziv bound for rates ranging from 0.48 to 4.64 bits per sample."},"correct_answer":{"kind":"string","value":"We examine successive refinement for the Wyner-Ziv problem described in a recent paper by Steinberg and Merhav, where the authors showed that if the side information for all stages is identical, then the jointly Gaussian source with squared error distortion measure is successively refinable. We first extend this result to the case where the difference between the source and the side information is Gaussian and independent of the side information. As a byproduct, we give an alternative proof that the Wyner-Ziv problem for these sources has no rate loss-a result that was recently shown by Pradhan et al. through invoking the duality between the Gaussian Wyner-Ziv problem and the Costa problem. We then perform layered Wyner-Ziv code design for this general type of source based on nested scalar quantization, bit-plane coding, and low-density parity check (LDPC) code-based Slepian-Wolf coding (source coding with side information). We show that density evolution can be used to analyze the Slepian-Wolf code performance, provided that certain symmetry conditions, which have been dubbed dual symmetry, are satisfied by the hypothetical channel between the source and the side information. We also show that the dual symmetry condition is indeed satisfied by the hypothetical channel in our Slepian-Wolf coding setup. This justifies the use of density evolution in our LDPC code-based Slepian-Wolf code design for Wyner-Ziv coding. For the jointly Gaussian source, our layered coder performs 1.29 to 3.45 dB from the Wyner-Ziv bound for rates ranging from 0.47 to 4.68 bits per sample. When the side information is Laplacian and the source equals the side information plus an independent Gaussian noise term, our layered coder performs 1.33 to 3.90 dB from the Wyner-Ziv bound for rates ranging from 0.48 to 4.64 bits per sample."},"documents":{"kind":"list like","value":["Title: Lossy-to-lossless ROI coding of chromosome images using modified SPIHT and EBCOT\nYear: 2002\n\nAbstract: This paper proposes a lossy-to-lossless region of interest (ROI) compression scheme based on set partitioning in hierarchical trees (SPIHT) [I] and embedded block coding with optimized truncation (EBCOT) [2] (EBCOT is the base of the JPEG-2000 [3] standard). However, SPIHT does not support ROI coding and JPEG-2000 does not allow lossy-to-lossless ROI compression. For our application, we modify the original SPIHT and EBCOT algorithms for lossy-to-lossless ROI coding of both the foreground and the background of chromosome images. Experiments show that our implementations offer better compression performance with exact ROI support than other image coders.","Title: Cooperation in the low power regime for the MAC using multiplexed rateless codes\nYear: 2010\n\nAbstract: In this paper, we consider cooperation in the low power (low SNR) regime for the multiple access channel with the assumption that the transmitters have no channel state information. A relevant performance measure to consider is therefore the outage capacity. We develop cooperation methods based on multiplexed coding in conjunction with rateless codes and find the achievable rates and in particular the minimum energy per bit required to achieve a certain outage probability. We consider two modes of operation: full duplex [code-division multiple access (CDMA)], where nodes can transmit and receive simultaneously on the same frequency hand, and half duplex [frequency-division multiple access (FDMA)], where the nodes transmit and listen on different frequency bands. We show that, perhaps surprisingly, there is little loss in performance when using FDMA. Furthermore, our results show that multiplexed rateless codes come within 0.1 dB of the outer bound on capacity. We also develop practical rateless coding methods for FDMA using multiplexed Raptor codes which operate within 0.52 and 1.1 dB of the theoretical limit for the two- and four-user case, respectively.","Title: Witsenhausen–Wyner Video Coding\nYear: 2011\n\nAbstract: Inspired by Witsenhausen and Wyner's 1980 (now expired) patent on “interframe coder for video signals,” this paper presents a Witsenhausen-Wyner video codec, where the motion-compensated previously decoded video frame is used at the decoder as side information for joint decoding. Specifically, we replace predictive Inter coding in H.264/AVC by the syndrome-based coding scheme of Witsenhausen and Wyner, while keeping the Intra and Skip modes of H.264/AVC unchanged. We employ forward motion estimation at the encoder and send the motion vectors to help generate side information at the decoder, since our focus is not on low-complexity encoding. We also examine the tradeoff between the motion vector resolution and coding efficiency. Within the Witsenhausen-Wyner coding mode, we optimize the decision between syndrome coding and entropy coding among different discrete cosine transform (DCT) bands and among different bit-planes within each DCT coefficient. Extensive simulations of video transmission over wireless networks show that Witsenhausen-Wyner video coding is more robust against channel errors than H.264/AVC. The price paid for enhanced error-resilience with Witsenhausen-Wyner coding is a small loss in compression efficiency.","Title: Nested convolutional/turbo codes for the binary Wyner-Ziv problem\nYear: 2003\n\nAbstract: ABSTRACT We show how,concatenated (convolutional) codes can be used to compress,close to the Wyner-Ziv limit for binary sources. Focusing on the case of lossy compression,of an equiprobable memoryless,binary source with side informa- tion at the decoder, the approach is based on nested bi- nary linear codes, which is the extension of Wyner’s lossless compression scheme to the lossy case proposed by Shamai, Verdu and Zamir. Based on our previous work on loss- less compression with concatenated codes, we are able to combine,the only two previously suggested nested schemes into a novel turbo scheme,with improved performance. Our scheme can come within 0.09 bits from the theoretical limit, which to our knowledge,is the first result ever reported for the binary Wyner-Ziv problem.","Title: Iterative decoding of differentially space-time coded multiple descriptions of images\nYear: 2003\n\nAbstract: We consider transporting images over wireless fading channels rather than the on-off channels considered in most works related to multiple description (MD) coding. The new idea is to use iterative (turbo) decoding techniques developed for serially concatenated coding systems to improve the performance of the receiver in successive decoding iterations. We treat MD coding, realized by embedded image coding plus unequal error protection (e.g., product code structure), as the outer constituent code and use a differential space-time code as the inner constituent code. Experimental results show that our iterative scheme can effectively improve the system performance. Furthermore, most of the gain in PSNR is achieved with only one iteration in the low SNR range, e.g., 0-20 dB.","Title: Multiuser resource allocation for video transmission over a chip-interleaved multicarrier system\nYear: 2007\n\nAbstract: We propose a 4G system for transmission of video from a server at the base station to numerous wireless clients. We employ the latest technology in scalable video compression (3-D wavelet video coding) and in channel coding (punctured turbo codes); for the physical layer, we resort to the multicarrier chip-interleaved system with two-layer interleaving, which achieves high spectral efficiency and is very suitable for downlink applications. We develop fast algorithms for a cross-layer resource allocation that minimize the expected distortion of the reconstructed video averaged over all clients. The algorithms find a near-optimal power, bandwidth, and subcarrier allocation at the physical layer and a source-channel symbol allocation at the application layer. Our experimental results demonstrate that such a cross-layer optimization framework leads to higher quality performance of the overall system. Copyright (c) 2007 John Wiley & Sons, Ltd.","Title: Compress-spread-forward with multiterminal source coding and complete complementary sequences\nYear: 2009\n\nAbstract: We propose a new technique, compress-spread-forward (CSF), for high-performance wireless streaming from two base stations in parallel. CSF uses multiterminal source coding for efficient source compression and complete complementary sequences for error-free multiple access and synchronization. Our practical design shows significant performance gains due to spatial diversity and distributed source coding.","Title: Multiresolution Watermarking for Images and Video: A Unified Approach\nYear: 1998\n\nAbstract: This paper proposes a unified approach to digital watermarking of images and video based on the 2D and 3D discrete wavelet transforms. The hierarchical nature of the wavelet representation allows multiresolutional detection of the digital watermark, which is a Gaussian distributed random vector added to all the highpass bands in the wavelet domain. We show that, when subjected to distortion from compression or image halftoning, the corresponding watermark can still be correctly identified at each resolution (excluding the lowest one) in the wavelet domain. Computational saving from such a multiresolution watermarking framework is obvious, especially for the video care.","Title: Optimal Resource Allocation for Wireless Video over CDMA Networks\nYear: 2003\n\nAbstract: We present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. We map an embedded video bitstream, which is encoded into multiple independently decodable layers by 3D-ESCOT video coding technique, to multiple CDMA channels. One video source layer is transmitted over one CDMA channel. Each video source layer is protected by a product channel code structure. A product channel code is obtained by the combination of a row code based on rate-compatible punctured convolutional code (RCPC) with cyclic redundancy check (CRC) error detection and a source-channel column code, i.e., systematic rate-compatible Reed-Solomon (RS) style erasure code. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation, i.e., the optimal unequal Reed-Solomon code source/parity rate allocations and the optimal RCPC rate protection for each channel. In formulating such an optimization problem, we make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. The channel is modeled as the concatenation of wireless BER channel and a wireline packet erasure channel with a fixed packet loss probability. By solving the optimization problem, we obtain the optimal power level allocation and the optimal transmission rate allocation over multiple CDMA channels. For each CDMA channel, we also employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Simulation results show that the proposed framework allows the video quality to degrade gracefully as the fading worsens or the bandwidth decreases, and it offers improved video quality at the receiver.","Title: Real-time unequal error protection algorithms for progressive image transmission\nYear: 2003\n\nAbstract: We consider unequal error protection strategies for the efficient progressive transmission of embedded image codes over noisy channels. In progressive transmission, the reconstruction quality is important not only at the target transmission rate but also at the intermediate rates. An adequate error protection strategy may, thus, consist of optimizing the average performance over the set of intermediate rates. The performance can be the expected number of correctly decoded source bits or the expected distortion. For the rate-based performance, we prove some interesting properties of an optimal solution and give an optimal linear-time algorithm to compute it. For the distortion-based performance, we propose an efficient linear-time local search algorithm. For a binary symmetric channel, two state-of-the-art source coders (SPIHT and JPEG2000), we compare the progressive ability of our proposed solutions to that of the strategies that optimize the end-to-end performance of the system. Experimental results showed that the proposed solutions had a slightly worse performance at the target transmission rate and a better performance at most of the intermediate rates, especially at the lowest ones.","Title: Packet loss protection of embedded data with fast local search\nYear: 2002\n\nAbstract: Unequal loss protection with systematic Reed-Solomon codes al- lows reliable transmission of embedded multimedia over packet erasure channels. The design of a fast algorithm with low memory requirements for the computation of an unequal loss protection solution is essential in real-time systems. Because the determi- nation of an optimal solution is time-consuming, fast suboptimal solutions have been used. In this paper, we present a fast iterative improvement algorithm with negligible memory requirements. Ex- perimental results for the JPEG2000, 2D, and 3D set partitioning in hierarchical trees (SPIHT) coders showed that our algorithm provided close to optimal peak signal-to-noise ratio (PSNR) per- formance, while its time complexity was significantly lower than that of all previously proposed algorithms.","Title: On code design for the Slepian-Wolf problem and lossless multiterminal networks\nYear: 2006\n\nAbstract: A Slepian-Wolf coding scheme for compressing two uniform memoryless binary sources using a single channel code that can achieve arbitrary rate allocation among encoders was outlined in the work of Pradhan and Ramchandran. Inspired by this work, we address the problem of practical code design for general multiterminal lossless networks where multiple memoryless correlated binary sources are separately compressed and sent; each decoder receives a set of compressed sources and attempts to jointly reconstruct them. First, we propose a near-lossless practical code design for the Slepian-Wolf system with multiple sources. For two uniform sources, if the code approaches the capacity of the channel that models the correlation between the sources, then the system will approach the theoretical limit. Thus, the great advantage of this design method is its possibility to approach the theoretical limits with a single channel code for any rate allocation among the encoders. Based on Slepian-Wolf code constructions, we continue with providing practical designs for the general lossless multiterminal network which consists of an arbitrary number of encoders and decoders. Using irregular repeat-accumulate and turbo codes in our designs, we obtain the best results reported so far and almost reach the theoretical bounds.","Title: 3D scene reconstruction by multiple structured-light based commodity depth cameras\nYear: 2012\n\nAbstract: Commodity depth cameras have attracted a lot of research interest recently, in particular the structured-light based Kinect cameras available on the mass market. One important application of such cameras is 3D scene reconstruction and view synthesis. However, a single depth camera often has limited field of view and there is missing depth information when synthesizing a virtual view from a new viewpoint. In this paper, we study the problem of 3D scene reconstruction from multiple structured-light based depth cameras. Since multiple cameras may cause severe interference in the regions where the projected light overlaps, we present a novel planesweeping based algorithm to handle such interference. The proposed algorithm takes into account the correlation between multiple projectors and the infrared images as well as the correlation between the infrared images, thereby recovering the depth information for both overlapped and non-overlapped regions. Simulation results demonstrate that the proposed solution is very effective on various scenes.","Title: Distributed Compression of Linear Functions: Partial Sum-Rate Tightness and Gap to Optimal Sum-Rate\nYear: 2014\n\nAbstract: We consider the problem of distributed compression of the difference Z = Y1 - cY2 of two jointly Gaussian sources Y1 and Y2 under an MSE distortion constraint D on Z. The rate region for this problem is unknown if the correlation coefficient ρ and the weighting factor c satisfy cρ > 0. Inspired by Ahlswede and Han's scheme for the problem of distributed compression of the modulo-2 sum of two binary sources, we first propose a hybrid random-structured coding scheme that is capable of saving the sum-rate over both the random quantize-and-bin (QB) coding scheme and Krithivasan and Pradhan's structured lattice coding scheme. The main idea is to use a random coding component in the first layer to adjust the source correlation so that the structured coding component in the second layer can be more efficient with the outputs from the first layer as decoder side information. We then provide a new sum-rate lower bound for the problem in hand by connecting it to the Gaussian two-terminal source coding problem with covariance matrix distortion constraint. Our lower bound not only improves existing bounds in many cases, but also allows us to prove sum-rate tightness of the QB scheme when c is either relatively small or large and D is larger than some threshold. Furthermore, our lower bound enables us to show that our new hybrid scheme performs within two b/s from the optimal sum-rate for all values of ρ, c, and D.","Title: Optimal rate allocation in progressive joint source-channel coding for image transmission over CDMA networks\nYear: 2003\n\nAbstract: This paper presents an optimal rate allocation scheme in joint source-channel coding (JSCC) for image transmission over CDMA networks. Our scheme first uses progressive joint source-channel codes [V. Stankovic et al., Sep. 2002] to generate operational transmission rate-distortion (TR-D) functions of different multiple-access channels with different BERs. The Lagrange multiplier is then employed to set the optimal rate allocation among different channels, subject to a total transmission rate constraint. Progressive JSCC offers the scalability feature that is very attractive for handling bandwidth variations in wireless communications. By extending the rate-distortion function in source coding to the TR-D function in JSCC, our work borrows the \"equal slope\" argument [Y. Shoham and A. Gersho, Sep. 1988] to effectively solve the rate allocation problem in JSCC for multi-channel image transmission. Experiments show that our scheme runs in real time and provides competitive performance at all intermediate transmission rates.","Title: Computing the channel capacity and rate-distortion function with two-sided state information\nYear: 2005\n\nAbstract: In this correspondence, we present iterative algorithms that numerically compute the capacity-power and rate-distortion functions for coding with two-sided state information. Numerical examples are provided to demonstrate efficiency of our algorithms.","Title: Distributed Source Coding for Multimedia Multicast Over Heterogeneous Networks\nYear: 2007\n\nAbstract: Real-time multimedia multicast over wireless networks is an exciting application that has generated a lot of interest recently. Its main challenge lies in the stringent bandwidth and time-delay requirements of real-time multimedia and severe impairments of the wireless channels. We develop a network-aware cross-layer design for multimedia multicast over heterogeneous wireless-wireline networks, th...","Title: Asymmetric code design for remote multiterminal source coding\nYear: 2004\n\nAbstract: Asymmetric code design for remote multiterminal source coding in the quadratic Gaussian case is presented in this paper. For remote multiterminal source coding of X, to achieve the minimum sum rate of the two independent encoders subject to a fidelity criterion d, theoretical bounds were derived independently. The main idea is to quantize the first observation Y1 and apply Wyner-Ziv coding on Y2 by using the quantized version of Y1 as side information in an efficient asymmetric coding scheme. The practical code design gives results that are very close to the sum-rate bound.","Title: Progressive coding of medical volumetric data using three-dimensional integer wavelet packet transform\nYear: 1998\n\nAbstract: Examines progressive lossy-to-lossless compression of medical volumetric data using 3D integer wavelet packet transforms and set partitioning in hierarchical trees (SPIHT). To achieve good lossy coding performance, we describe a 3D integer wavelet packet transform that allows implicit bit shifting of wavelet coefficients to approximate a 3D unitary transformation. We also address context modeling for efficient entropy coding within the SPIHT framework. Both lossy and lossless coding performances are better than those reported by A. Bilgin et al. (1998)","Title: Joint error control and power allocation for video transmission over CDMA networks with multiuser detection\nYear: 2002\n\nAbstract: Error control and power allocation for transmitting wireless video over CDMA networks are considered in conjunction with multiuser detection. We map a layered video bitstream to several CDMA fading channels and inject multiple source/parity layers into each of these channels at the transmitter. At the receiver, we employ a linear minimum mean-square error (MMSE) multiuser detector in the uplink and two types of blind linear MMSE detectors in the downlink, for demodulating the received data. For given constraints on the available bandwidth and transmit power, the transmitter determines the optimal power allocation among different CDMA fading channels and the optimal number of source and parity packets to send that offer the best video quality. Simulation results show a performance gain of up to 1.5 dB with joint optimization over that with rate optimization only.","Title: A DCT-based embedded image coder\nYear: 1996\n\nAbstract: Since Shapiro (see ibid., vol.41, no.12, p. 445, 1993) published his work on embedded zerotree wavelet (EZW) image coding, there have been increased research activities in image coding centered around wavelets. We first point out that the wavelet transform is just one member in a family of linear transformations, and the discrete cosine transform (DCT) can also be coupled with an embedded zerotree quantizer. We then present such an image coder that outperforms any other DCT-based coder published in the literature, including that of the Joint Photographers Expert Group (JPEG). Moreover, our DCT-based embedded image coder gives higher peak signal-to-noise ratios (PSNR) than the quoted results of Shapiro's EZW coder.","Title: Introduction to the Issue on MIMO-Optimized Transmission Systems for Delivering Data and Rich Content\nYear: 2008\n\nAbstract: The 11 papers in this special issue focus on MIMO-optimized transmission systems for delivering data and rich content. The papers are summarized here.","Title: Compress-forward coding with BPSK modulation for the half-duplex Gaussian relay channel\nYear: 2009\n\nAbstract: This paper studies compress-forward (CF) coding with BPSK modulation for the half-duplex Gaussian relay channel. In CF relaying, Wyner-Ziv coding is applied at the relay to exploit the joint statistics between signals at the relay and the destination. We propose Slepian-Wolf coded nested scalar quantization (SWCNSQ) for practical Wyner-Ziv coding at the relay. We first provide the achievable rate of SWCNSQ based CF relaying as a performance benchmark, and then present a practical code design using low-density parity-check (LDPC) codes for error protection at the source, and nested scalar quantization plus irregular-repeat accumulation (IRA) codes for CF coding at the relay. The degree distributions of the LDPC and IRA codes are optimized using extrinsic information transfer charts and Gaussian approximation. Under discretized density evolution for asymptotically large block lengths, our optimized code design operates 0.11-0.21 dB away from the SWCNSQ limit for CF relaying. Simulations with LDPC/IRA codes of length 2 × 105 show a performance gap of 0.27-0.38 dB from the achievable rate.","Title: Sending two Gaussians over the Gaussian MAC with bandwidth expansion\nYear: 2012\n\nAbstract: The problem of sending two Gaussian sources over the Gaussian multiple access channel (MAC) with bandwidth expansion is studied. In this problem, two distributed transmitters desire to describe the two Gaussian sources to a common receiver subject to desired communication quality requirements and bandwidth expansion constraint. Of our interests is the minimum power and the transmission schemes to achieve power efficiency. Achievable bounds on the minimum power are given in this work.","Title: Distributed Source And Joint Source-Channel Coding: From Theory To Practice\nYear: 2005\n\nAbstract: This paper reviews the theory behind distributed source coding and distributed source-channel coding and surveys the progress made in code design during the last years.","Title: Design of Slepian-Wolf Codes by Channel Code Partitioning\nYear: 2004\n\nAbstract: A Slepian-Wolf coding scheme that can achieve arbitrary rate allocation amongtwo encoders was outlined in the work of Pradhan and Ramchandran. Inspired by thiswork, we start with a detailed solution for general (asymmetric or symmetric) Slepian-Wolfcoding based on partitioning a single systematic channel code, and continuewith practical code designs using advanced channel codes. By using systematic IRAand turbo codes, we devise a powerful scheme that is capable of approaching any pointon the Slepian-Wolf bound. We further study an extension of the technique to multiplesources, and show that for a particular correlation model among the sources, a singlepractical channel code can be designed for coding all the sources in symmetric andasymmetric scenarios. If the code approaches the capacity of the channel that modelsthe correlation between the sources, then the system will approach the Slepian-Wolflimit. Using systematic IRA and punctured turbo codes for coding two binary sources,each being independent identically distributed, with correlation modeled by a binarysymmetric channel, we obtain results which are 0.04 bits away from the theoreticallimit in both symmetric and asymmetric Slepian-Wolf settings.","Title: Efficient rate allocation for progressive image transmission via unequal error protection over finite-state Markov channels\nYear: 2005\n\nAbstract: This paper proposes a unified framework for addressing progressive image transmission over noisy channels based on the finite-state Markov channel (FSMC) model. FSMC models are simple yet general enough to model binary symmetric, Gilbert-Elliott, and fading channels. They allow error sequence analysis that facilitates quantifying the statistical characteristics of the embedded bitstreams transmitted over FSMC in closed form. Using a concatenation of rate-compatible puncturing convolutional code and cyclic redundancy check code for error protection, we use a concatenation of rate-compatible punctured convolutional code and cyclic redundancy check code for error protection, which results in an unequal error protection (UEP) system, and find (sub-)optimal rate allocation solutions for our setup. By mapping fading channels to FSMCs, the JSCC problem is thus solved without the burden of simulations using an image-dependent lookup table. Fast algorithms are proposed to search for the optimal UEP. Experiments on embedded image bitstreams over FSMCs confirm our analytical results.","Title: Code design for MIMO broadcast channels\nYear: 2009\n\nAbstract: Recent information-theoretic results show the optimality of dirty-paper coding (DPC) in achieving the full capacity region of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC). This paper presents a DPC based code design for BCs. We consider the case in which there is an individual rate/signal-to-interference-plus-noise ratio (SINR) constraint for each user. For a fixed transmitter power, we choose the linear transmit precoding matrix such that the SINRs at users are uniformly maximized, thus ensuring the best bit-error rate performance. We start with Cover's simplest two-user Gaussian BC and present a coding scheme that operates 1.44 dB from the boundary of the capacity region at the rate of one bit per real sample (b/s) for each user. We then extend the coding strategy to a two-user MIMO Gaussian BC with two transmit antennas at the base-station and develop the first limit-approaching code design using nested turbo codes for DPC. At the rate of 1 b/s for each user, our design operates 1.48 dB from the capacity region boundary. We also consider the performance of our scheme over a slow fading BC. For two transmit antennas, simulation results indicate a performance loss of only 1.4 dB, 1.64 dB and 1.99 dB from the theoretical limit in terms of the total transmission power for the two, three and four user case, respectively.","Title: Layered Wyner-Ziv video coding for transmission over unreliable channels\nYear: 2006\n\nAbstract: Based on recent works on Wyner-Ziv coding (WZC) (or lossy source coding with decoder side information), this paper considers the case with noisy channel and addresses distributed joint source-channel coding (JSCC), while targeting at the important application of scalable video transmission over wireless networks. In WZC, after quantization, Slepian-Wolf coding (SWC) is used to reduce the rate. SWC is traditionally realized by sending syndromes of a linear channel code. Since syndromes of the channel code can only compress but cannot protect, for transmission over noisy channels, additional error protection is needed. However, instead of using one channel code for SWC and one for error protection, our idea is to use a single channel code to achieve both compression and protection. We replace the traditional syndrome-based SWC scheme by the parity-based one, where only parity bits of the Slepian-Wolf channel code are sent. If the amount of transmitted parity bits increases above the Slepian-Wolf limit, the added redundancy is exploited to cope against the noise in the transmission channel. Using irregular repeat-accumulate codes for practical parity-based SWC, we design a novel layered Wyner-Ziv video coder which is robust to channel failures and thus very suitable for wireless communications. Our simulation results show great advantages of the proposed solution based on JSCC compared to the traditional approach where source and channel coding are performed separately.","Title: On the sum-rate loss of quadratic Gaussian multiterminal source coding\nYear: 2011\n\nAbstract: This work studies the sum-rate loss of quadratic Gaussian multiterminal source coding, i.e., the difference between the minimum sum-rates of distributed encoding and joint encoding (both with joint decoding) of correlated Gaussian sources subject to MSE distortion constraints on individual sources. It is shown that under the non-degraded assumption, i.e., all target distortions are simultaneously achievable by a Berger-Tung scheme, the supremum of the sum-rate loss of distributed encoding over joint encoding of L jointly Gaussian sources increases almost linearly in the number of sources L, with an asymptotic slope of 0.1083 b/s per source as L goes to infinity. This result is obtained even though we currently do not have the full knowledge of the minimum sum-rate for the distributed encoding case. The main idea is to upper-bound the minimum sum-rate of multiterminal source coding by that achieved by parallel Gaussian test channels while lower-bounding the minimum sum-rate of joint encoding by a reverse water-filling solution to a relaxed joint encoding problem of the same set of Gaussian sources with a sum-distortion constraint (that equals the sum of the individual target distortions). We show that under the non-degraded assumption, the supremum difference between the upper bound for distributed encoding and the lower bound for joint encoding is achieved in the bi-eigen equal-variance with equal distortion case, in which both bounds are known to be tight.","Title: An improved lattice-based scheme for lossy distributed compression of linear functions\nYear: 2011\n\nAbstract: It has recently been showed that lattice/structured codes can outperform random/unstructured codes in a number of scenarios of distributed source coding. One such instance involves lossy distributed compression of linear functions of Gaussian sources, which is the focus of this paper. Existing structured schemes employ “good” lattices for quantization and binning, however, the remaining correlation between the lattice coset indices are not exploited in an efficient way, leading to suboptimal performance when the target distortion is small. This paper proposes a new lattice-based scheme that is capable of eliminating the redundancy among coset indices and achieving a smaller sum-rate than existing schemes. The main novelty lies in the use of a hidden relationship between the coset planes of the quantization indices, and the enlarged set of choices for the quantizers as well as the linear estimation coefficients.","Title: Block-based variable density compressed image sampling\nYear: 2012\n\nAbstract: Compressed sampling (CS) is a technique that enables signal reconstruction at sub-Nyquist sampling rate. A key problem in CS is how to design the sampling scheme. In this paper, we propose a novel sampling method for compressed image sampling, which exploits a priori information and uses a block-based strategy to improve image reconstruction. Our block-based sampling scheme assigns more samples to blocks with more high-frequency contents while making sure that important coefficients of each block are sampled. Simulation results show that our proposed method outperforms existing methods on both reconstruction quality and running time.","Title: Multiresolution watermarking for images and video\nYear: 1999\n\nAbstract: This paper proposes a unified approach to digital watermarking of images and video based on the two- and three-dimensional discrete wavelet transforms. The hierarchical nature of the wavelet representation allows multiresolutional detection of the digital watermark, which is a Gaussian distributed random vector added to all the high-pass bands in the wavelet domain. We show that when subjected to distortion from compression or image halftoning, the corresponding watermark can still be correctly identified at each resolution (excluding the lowest one) in the wavelet domain. Computational savings from such a multiresolution watermarking framework is obvious, especially for the video case","Title: A deblocking algorithm for JPEG compressed images using overcomplete wavelet representations\nYear: 1997\n\nAbstract: This paper introduces a new approach to deblocking of JPEG compressed images using overcomplete wavelet representations. By exploiting cross-scale correlations among wavelet coefficients, edge information in the JPEG compressed images is extracted and protected, while blocky noise in the smooth background regions is smoothed out in the wavelet domain. Compared with the iterative methods reported in the literature, our simple wavelet-based method has much lower computational complexity, yet it is capable of achieving the same peak signal-to-noise ratio (PSNR) improvement as the best iterative method and giving visually very pleasing images as well","Title: Recursive bilateral filter for encoder-integrated video denoising\nYear: 2012\n\nAbstract: Video denoising based on temporal or spatiotemporal filtering is highly effective but computationally expensive due to the requirement of motion estimation. Encoder-integrated denoising is an efficient framework that embeds the filtering process into the encoding pipeline so that motion estimation for denoising can be avoided. State-of-the-arts encoder-integrated methods use Least Minimum Mean Square Error (LMMSE) optimal filters to reduce noise based on additive noise models. However, in practice, the LMMSE filters could result in blurred edges and visual artifacts due to inaccurate image signal estimation caused by outlier input samples and non-adaptivity within macroblocks. This paper presents new recursive bilateral filters that can be easily integrated into video encoders to tackle the limitations of the LMMSE filters. The robustness of the bilateral filters results in substantially better objective and subjective quality with marginal computation cost increase.","Title: Scalable audio coding using the nonuniform modulated complex lapped transform\nYear: 2001\n\nAbstract: This paper introduces a scalable audio coder using the nonuniform modulated complex lapped transform (NMCLT), which is a new nonuniform oversampled filter bank with a better combination of time- and frequency-domain localization than previous designs. Masking functions for different critical Bark bands are first calculated directly from the NMCLT coefficients as perceptual weights and arithmetic coding is then used to compress bit planes of the weighted NMCLT coefficients to generate a perceptually scalable audio bitstream. The loss in coding performance due to oversampling is offset by limiting the amount of redundancy in the transform and exploiting the correlations among the NMCLT basis functions. Experiments show that our new coder outperforms a coder with the modulated lapped transform (MLT) both objectively and subjectively.","Title: Diversity analysis for space-time-frequency (STF) coded MIMO system with a general correlation model\nYear: 2013\n\nAbstract: Previous works on space-time-frequency (STF) codes have focused on frequency-selective but independent fading channels for MIMO-OFDM systems. However, insufficient antenna space, mobile scenarios, and multipath in practice cause correlation in the spatial, temporal, and frequency domains. This paper studies the effect of STF coding on the performance of MIMO-OFDM systems with general spatial, temporal, and frequency/path correlated channels. Specifically, we first derive an upper bound on the maximum achievable diversity and then prove achievability by giving an STF code design example. Finally, we show that our general diversity result recovers those in the existing literature for special correlation structures.","Title: On the minimum energy of sending Gaussian multiterminal sources over the Gaussian MAC\nYear: 2013\n\nAbstract: We study the minimum energy of sending Gaussian multiterminal sources over the Gaussian multiple access channel (MAC). Distributed transmitters observe Gaussian multiterminal sources and describe their observations to a central decoder, which desires to reconstruct the sources under MSE constraints. We first lower bound the minimum energy by a cut-set argument which couples the transmitted signals and reconstruction errors. For achievability, separate source-channel coding is first studied as a benchmark. We then find out the minimum energy that can be achieved uncoded transmission. A hybrid digital/analog scheme is proposed to achieve the best known energy performance.","Title: Subspace-based prototyping and classification of chromosome images.\nYear: 2005\n\nAbstract: Chromosomes are essential genomic information carriers. Chromosome classification constitutes an important part of routine clinical and cancer cytogenetics analysis. Cytogeneticists perform visual interpretation of banded chromosome images according to the diagrammatic models of various chromosome types known as the ideograms, which mimic artists' depiction of the chromosomes. In this paper, we present a subspace-based approach for automated prototyping and classification of chromosome images. We show that 1) prototype chromosome images can be quantitatively synthesized from a subspace to objectively represent the chromosome images of a given type or population, and 2) the transformation coefficients (or projected coordinate values of sample chromosomes) in the subspace can be utilized as the extracted feature measurements for classification purposes. We examine in particular the formation of three well-known subspaces, namely the ones derived from principal component analysis (PCA), Fisher's linear discriminant analysis, and the discrete cosine transform (DCT). These subspaces are implemented and evaluated for prototyping two-dimensional (2-D) images and for classification of both 2-D images and one-dimensional profiles of chromosomes. Experimental results show that previously unseen prototype chromosome images of high visual quality can be synthesized using the proposed subspace-based method, and that PCA and the DCT significantly outperform the well-known benchmark technique of weighted density distribution functions in classifying 2-D chromosome images.","Title: Determination of the optimal number of features for quadratic discriminant analysis via the normal approximation to the discriminant distribution\nYear: 2005\n\nAbstract: Given the joint feature-label distribution, increasing the number of features always results in decreased classification error; however, this is not the case when a classifier is designed via a classification rule from sample data. Typically, for fixed sample size, the error of a designed classifier decreases and then increases as the number of features grows. The problem is especially acute when sample sizes are very small and the potential number of features is very large. To obtain a general understanding of the kinds of feature-set sizes that provide good performance for a particular classification rule, performance must be evaluated based on accurate error estimation, and hence a model-based setting for optimizing the number of features is needed. This paper treats quadratic discriminant analysis (QDA) in the case of unequal covariance matrices. For two normal class-conditional distributions, the QDA classifier is determined according to a discriminant. The standard plug-in rule estimates the discriminant from a feature-label sample to obtain an estimate of the discriminant by replacing the means and covariance matrices by their respective sample means and sample covariance matrices. The unbiasedness of these estimators assures good estimation for large samples, but not for small samples. Our goal is to find an essentially analytic method to produce an error curve as a function of the number of features so that the curve can be minimized to determine an optimal number of features. We use a normal approximation to the distribution of the estimated discriminant. Since the mean and variance of the estimated discriminant will be exact, these provide insight into how the covariance matrices affect the optimal number of features. We derive the mean and variance of the estimated discriminant and compare feature-size optimization using the normal approximation to the estimated discriminant with optimization obtained by simulating the true distribution of the estimated discriminant. Optimization via the normal approximation to the estimated discriminant provides huge computational savings in comparison to optimization via simulation of the true distribution. Feature-size optimization via the normal approximation is very accurate when the covariance matrices differ modestly. The optimal number of features based on the normal approximation will exceed the actual optimal number when there is large disagreement between the covariance matrices; however, this difference is not important because the true misclassification error using the number of features obtained from the normal approximation and the number obtained from the true distribution differ only slightly, even for significantly different covariance matrices.","Title: An optimal packetization scheme for fine granularity scalable bitstream\nYear: 2002\n\nAbstract: This paper addresses the problem of optimal packetization for a fine granularity scalable (FGS) bitstream. A very general performance metric for streaming FGS bitstreams over packet erasure networks is first defined and analyzed. Then three packetization strategies, namely baseline packetization, binary-tree packetization and optimal packetization are presented, justified and compared. Finally, some experimental results are presented to demonstrate the effectiveness of the packetization schemes.","Title: Scalable image transmission using rate-compatible irregular repeat accumulate (IRA) codes\nYear: 2002\n\nAbstract: This paper considers designing and applying rate-compatible irregular repeat accumulate (IRA) codes for scalable image transmission over binary symmetric channels. IRA codes of different rates are obtained by puncturing the parity bits of a mother IRA code which uses a systematic encoder. One of the main ideas presented here is the design of the mother code such that the entire set of higher rate codes obtained by puncturing are good. Using the Viterbi algorithm for finding the optimal unequal error protection of JPEG2000 bit streams, we present better results with IRA codes than those reported with turbo codes. The proposed IRA codes also have lower decoding complexity than the turbo codes.","Title: Code design for quadratic Gaussian multiterminal source coding: the symmetric case\nYear: 2009\n\nAbstract: Whereas the theory and practice of two-terminal quadratic Gaussian multiterminal (MT) source coding is complete, the theory with more than two terminals is only partial, with the sum-rate limit only known in the symmetric case where all sources are positively symmetric and all target distortions equal. This paper proposes the first code design for quadratic Gaussian MT source coding in this symmetric setup. The aim is to approach corner points of the rate region via TCQ for quantization and LDPC codes for Slepian-Wolf compression. We provide high-rate analysis of our code design. Simulations with three and four terminals show a very small sum-rate loss.","Title: Optimal rate allocation for progressive fine granularity scalable video coding\nYear: 2001\n\nAbstract: We examine the enhancement-layer rate allocation problem in progressive fine granularity scalable (PFGS) video coding. The problem arises from the fact that different frames in the enhancement layer have different rates in PFGS coding. A rate-distortion (R-D) function for a multiframe group is first established for enhancement-layer PFGS coding, followed by experiments to verify its validity using real test sequences. Optimal rate allocation among frames in the group is then given based on the R-D function, together with a simple implementation that is suitable for applications such as streaming video. Experiments show that, compared with uniform bit allocation, optimal bit allocation not only makes the quality variation in decoded video much smoother, but also improves the average PSNR of PFGS coding by 0.3-0.5 dB.","Title: Efficient channel code rate selection algorithms for forward error correction of packetized multimedia bitstreams in varying channels\nYear: 2004\n\nAbstract: We study joint source-channel coding systems for the transmission of images over varying channels without feedback. We consider the situation where the channel statistics are unknown to the transmitter and focus on systems that enable good performance over a wide range of channel conditions. We first propose a linear-time channel code rate selection algorithm for a hybrid transmission system that combines packetization of an embedded wavelet bitstream into independently decodable packets and forward error correction with a concatenated cyclic redundancy check/rate-compatible punctured convolutional (RCPC) channel coder. We then consider an extension of this hybrid system with additional Reed-Solomon (RS) coding across the packets and give a linear-time algorithm for the efficient selection of both the RS and RCPC code rates. Experimental results for a wireline/wireless link modeled as the combination of a packet erasure channel and a Rayleigh flat-fading channel showed that our schemes significantly outperformed the best previous forward error correction systems in many situations where the actual channel parameter values deviated from the ones used in the optimization of the source-channel rate allocation.","Title: Real-time error protection of embedded codes for packet erasure and fading channels\nYear: 2004\n\nAbstract: Reliable real-time transmission of packetized embedded multimedia data over noisy channels requires the design of fast error control algorithms. For packet erasure channels, efficient forward error correction is obtained by using systematic Reed-Solomon (RS) codes across packets. For fading channels, state-of-the-art performance is given by a product channel code where each column code is an RS code and each row code is a concatenation of an outer cyclic redundancy check code and an inner rate-compatible punctured convolutional code. For each of these two systems, we propose a low-memory linear-time iterative improvement algorithm to compute an error protection solution. Experimental results for the two-dimensional and three-dimensional set partitioning in hierarchical trees coders showed that our algorithms provide close to optimal average peak signal-to-noise ratio performance, and that their running time is significantly lower than that of all previously proposed solutions.","Title: Face Hallucination Via Weighted Sparse Representation\nYear: 2013\n\nAbstract: By incorporating the priors of image positions, position-patch based face hallucination methods can produce high-quality results and save computation time. These methods represent the test image patch as a linear combination of the same position patches in a training dictionary, and the key issue is how to obtain the optimal coefficients. Due to stability and accuracy issues, methods based on least square estimation or sparse representation (SR) proposed so far are not satisfactory. In this paper, we improve existing SR methods by exploiting similarity between the test and training patches. In particular, we impose a similarity constraint (in terms of the distance between the test patch and bases in the dictionary) on the l(1) minimization regularization term and obtain the coefficients by solving a weighted SR problem. We also provide a new prospective on weighted SR and investigate its robustness to illumination variations. Experiments on commonly used database demonstrate that our method outperforms state of the art.","Title: Fast Forward Error Protection Of Packetized Multimedia Bitstreams For Transmission Over Varying Channels\nYear: 2003\n\nAbstract: We propose a real-time optimization algorithm that selects an appropriate channel code for hybrid systems that combine packetization of an embedded wavelet bitstream into independently decodable packets and forward error correction using a family of channel codes with error detection and error correction capability. Such systems are very powerful for the transmission of audio, images, and video over fading and erasure channels with varying statistics. We also give an implementation that uses an optimal packetization technique and a concatenated cyclic redundancy check/rate-compatible punctured convolutional coder. Experimental results show that the peak signal-to-noise ratio of the average mean square error of our system is up to 1.74 dB higher than that of the previous best hybrid system for a Rayleigh fading channel and a transmission rate of 0.25 bits per pixel. Finally, we compare the hybrid approach to a state-of-the-art approach that uses a product code to protect the information bitstream.","Title: Advanced motion threading for 3D wavelet video coding\nYear: 2004\n\nAbstract: This paper presents an advanced motion threading technique for improved performance in 3D wavelet coding. First, we extend an original motion threading idea of ours to a lifting- based implementation. Methods for enabling fractional-pixel alignment in motion threading and for processing many-to-one pixel mapping and non-referred pixels are proposed to reduce the wavelet boundary effects. Second, we devise an advanced motion threading technique, in which one set of motion vectors is generated for each temporal layer of wavelet coefficients for temporal scalability. In order to reduce the motion overhead information, especially at low bit rates, several correlated motion prediction modes at the macroblock level are defined to exploit the intra/inter layer correlation in motion vector coding. Finally, rate-distortion optimization is utilized in motion estimation to select the best motion prediction mode for each macroblock. With the new motion threading technique, we are able to achieve 1.5–6.0dB gain in average PSNR in 3D wavelet coding over our previous implementation of motion threading.","Title: Noise-injected neural networks show promise for use on small-sample expression data.\nYear: 2006\n\nAbstract: Overfitting the data is a salient issue for classifier design in small-sample settings. This is why selecting a classifier from a constrained family of classifiers, ones that do not possess the potential to too finely partition the feature space, is typically preferable. But overfitting is not merely a consequence of the classifier family; it is highly dependent on the classification rule used to design a classifier from the sample data. Thus, it is possible to consider families that are rather complex but for which there are classification rules that perform well for small samples. Such classification rules can be advantageous because they facilitate satisfactory classification when the class-conditional distributions are not easily separated and the sample is not large. Here we consider neural networks, from the perspectives of classical design based solely on the sample data and from noise-injection-based design.This paper provides an extensive simulation-based comparative study of noise-injected neural-network design. It considers a number of different feature-label models across various small sample sizes using varying amounts of noise injection. Besides comparing noise-injected neural-network design to classical neural-network design, the paper compares it to a number of other classification rules. Our particular interest is with the use of microarray data for expression-based classification for diagnosis and prognosis. To that end, we consider noise-injected neural-network design as it relates to a study of survivability of breast cancer patients.The conclusion is that in many instances noise-injected neural network design is superior to the other tested methods, and in almost all cases it does not perform substantially worse than the best of the other methods. Since the amount of noise injected is consequential, the effect of differing amounts of injected noise must be considered.","Title: On optimal subspaces for appearance-based object recognition\nYear: 2002\n\nAbstract: On the subject of optimal subspaces for appearance-based object recognition, it is generally believed that algorithms based on LDA (Linear Discriminant Analysis) are superior to those based on PCA (Principal Components Analysis), provided that relatively large training data sets are available (3, 5). In this paper, We show that while this is generally true for classification with the nearest-neighbor classifier, it is not always the case with a maximum-likelihood classifier. We support our claim by presenting both intuitively plausi- ble arguments and actual results on a large data set of human chromosomes. Our conjecture is that perhaps only when the underlying object classes are linearly separable would LDA be truly superior to other known subspaces of equal dimen- sionality.","Title: Progressive image transmission over differentially space-time coded OFDM systems\nYear: 2006\n\nAbstract: In this paper, we consider progressive image transmission over differentially space-time coded orthogonal frequency-division multiplexing (OFDM) systems and treat the problem as one of optimal joint source-channel coding (JSCC) in the form of unequal error protection (UEP), as necessitated by embedded source coding (e.g., SPIHT and JPEG 2000). We adopt a product channel code structure that is proven to provide powerful error protection and employ low-complexity decision-feedback decoding for differentially space-time coded OFDM without assuming channel state information. For a given SNR, the BER performance of the differentially spacetime coded OFDM system is treated as the channel condition in the JSCC/UEP design via a fast product code optimization algorithm so that the end-to-end quality of reconstructed images is optimized in the average minimum MSE sense. Extensive image transmission experiments show that SNR/BER improvements can be translated into quality gains in reconstructed images. Moreover, compared to another non-coherent detection algorithm, i.e., the iterative receiver based on expectation-maximization algorithm for the space-time coded OFDM systems, differentially space-time coded OFDM systems suffer some quality loss in reconstructed images. With the efficiency and simplicity of decision-feedback differential decoding, differentially space-time coded OFDM is thus a feasible modulation scheme for applications such as wireless image over mobile devices (e.g., cell phones). Copyright (C) 2006 John Wiley & Sons, Ltd.","Title: PAGER: a distributed algorithm for the dead-end problem of location-based routing in sensor networks\nYear: 2004\n\nAbstract: The dead-end problem is an importance issue of location-based routing in sensor networks, which occurs when a message falls into a local minimum using greedy forwarding. Current methods for this problem are insufficient either in eliminating traffic/path memorization or finding satisfied short paths. In this paper, we propose a novel algorithm, named partial-partition avoiding geographic routing (PAGER), to solve the problem. The basic idea of PAGER is to divide a sensor network graph into functional sub-graphs, and provide each sensor node with message forwarding directions based on these sub-graphs. That results in loop-free short paths without memorization of traffics/paths in sensor nodes. We implement our algorithm in a protocol and evaluate it in sensor networks with different parameters. Results show that PAGER generates considerably shorter paths, higher delivery ratio and lower energy consumption than the greedy perimeter stateless routing protocol. At the same time, PAGER achieves better performance in handling large-scale networks than the ad-hoc on-demand distance vector protocol","Title: The sum-rate bound for a new class of quadratic Gaussian multiterminal source coding problems\nYear: 2012\n\nAbstract: In this paper we show tightness of the Berger-Tung (BT) sum-rate bound for a new class of quadratic Gaussian multiterminal (MT) source coding problems dubbed bi-eigen equal-variance with equal distortion (BEEV-ED), where the L à L source covariance matrix has equal diagonal elements with two distinct eigenvalues, and the L target distortions are equal. Let K(K < L) be the number of larger eigenvalues, the BEEV covariance structure allows us to connect K i.i.d virtual Gaussian sources with the L given MT sources via an L à K semiorthogonal transform whose rows have equal Euclidean norm plus additive i.i.d. Gaussian noises, resulting in the two sets of sources being mutually conditional i.i.d. By relating the given MT source coding problem to a generalized Gaussian CEO problem with the K virtual sources as remote sources and the L MT sources as observations, we obtain a lower bound on the MT sum-rate, and show its achievability by BT schemes under the equal distortion constraints. Our BEEV-ED class of quadratic Gaussian MT source coding problems subsumes both the positive-symmetric case considered by Wagner et al. and the negative-symmetric case. Other examples, including a subclass of sources with BE circulant symmetric covariance matrices and equal distortion constraints, are also provided to highlight tightness of the sum-rate bound.","Title: Scalable image and video transmission using irregular repeat-accumulate codes with fast algorithm for optimal unequal error protection\nYear: 2004\n\nAbstract: This paper considers designing and applying punctured irregular repeat-accumulate (IRA) codes for scalable image and video transmission over binary symmetric channels. IRA codes of different rates are obtained by puncturing the parity bits of a mother IRA code, which uses a systematic encoder. One of the main ideas presented here is the design of the mother code such that the entire set of higher rate codes obtained by puncturing are good. To find a good unequal error protection for embedded bit streams, we employ the fast joint source-channel coding algorithm in Hamzaoui et al. to minimize the expected end-to-end distortion. We test with two scalable image coders (SPIHT and JPEG-2000) and two scalable video coders (3-D SPIHT and H.26L-based PFGS). Simulations show better results with IRA codes than those reported in Banister et al. with JPEG-2000 and turbo codes. The IRA codes proposed here also have lower decoding complexity than the turbo codes used by Banister et al.","Title: Source-Channel Coding For Algebraic Multiterminal Binning\nYear: 2004\n\nAbstract: This paper addresses practical code design problems for multiterminal communication networks. The basic element of a multiterminal network code is the binning scheme. We aim to develop a unified practical code design paradigm for related problems in multiterminal networks based on source-channel coding for algebraic binning. First, a framework based on Slepian-Woff coded quantization is highlighted for Wyner-Ziv coding and multiterminal source coding (e.g., the CEO problem). Then, a nested turbo scheme is proposed for Costa coding by exploiting the duality between Costa coding and Wyner-Ziv coding.","Title: Image enhancement using multiscale oriented wavelets\nYear: 2001\n\nAbstract: We describe a novel method of enhancing image geometric features using the oriented wavelets introduced in our earlier work (see Yu-Ping Wang, IEEE Trans. Image Proc., vol.8, no.12, p.1757-71, 1999). The poor directional selectivity of the conventional 2D wavelet transform has been circumvented by using this class of oriented wavelets. By taking advantage of directional wavelet decomposition, both the directional and scale correlation information are utilized for enhancing salient structures in images. To remove phase dependence, a pair of quadrature filters are used. The proposed algorithm has been applied to chromosome image enhancement. Comparisons of this algorithm with other approaches are presented","Title: Image enhancement using multiscale differential operators\nYear: 2001\n\nAbstract: Differential operators have been widely used for multiscale geometric descriptions of images. Efficient computation of these differential operators can be obtained by taking advantage of the spline techniques. We make use of a special class of these operators for image enhancement, with a particular application to chromosome image enhancement. These operators constitute a translation invariant wavelet transform well suited for the structural description of chromosome geometry. Based on the fact that the geometrical features like edges are correlated between different scales in the representation, a novel algorithm is designed to enhance the salient features of the image. Comparisons of this algorithm with other approaches are presented.","Title: Cooperation in the MAC channel using frequency division multiplexing\nYear: 2009\n\nAbstract: This paper considers cooperation in the low power/SNR regime for the multiple access channel. We assume that transmitters have no channel state information, and consider the outage capacity. We further assume that the nodes operate in half duplex. The nodes are multiplexed by assigning to each node a unique frequency band via frequency division multiplexing (FDM). A node transmits only on this band while listening on the others. We perform outage wideband analysis on FDM based cooperation, and show perhaps surprisingly that FDM loses very little in performance compared to the idealized situation where nodes can operate in full duplex. We then develop practical rateless coding methods for FDM using Raptor codes.","Title: On optimal packetization of embedded bitstreams\nYear: 2000\n\nAbstract: We investigate the problem of packetizing multiple embedded bitstreams to improve the error resilience of source codes. We discuss various packetization schemes against packet erasure at both low and high bit rates. We formulate various versions of packetization of multiple embedded bitstreams for minimum distortion as discrete optimization problems, and propose efficient algorithms to compute globally optimal solutions to these problems","Title: Joint UEP and layered source coding with application to transmission of JPEG-2000 coded images\nYear: 2001\n\nAbstract: This paper presents a joint source-channel coding framework based on layered source coding and Reed-Solomon channel coding for unequal error protection. An iterative procedure is described to search for the best source coding rate and the optimal UEP of layered bitstreams. We apply our JSCC technique to transmission of JPEG-2000 coded images over binary symmetric channels. Compared to results reported in the literature, our UEP based approach gives better results while having lower complexity","Title: A Robust Multi-Level Design for Dirty-Paper Coding.\nYear: 2013\n\nAbstract: We propose a robust close-to-capacity dirty-paper coding (DPC) design framework in which multi-level low density parity check (LDPC) codes and trellis coded quantization (TCQ) are employed as the channel and source coding components, respectively. The proposed design framework is robust in the sense that it yields close to capacity solutions in the high-, medium-, and low-rate regimes. This is in contrast to existing practical DPC schemes that perform well only in one or two of these regimes, but not all three. We design codes for transmission rates of 0.5, 1.0, 1.5, and 2.0 bits/sample (b/s) using one, two, three, and four LDPC levels; at a block length of 210 5 , the codes perform 0.95, 0.58, 0.55, and 0.54 dB from the corresponding information theoretic limits, respectively. We also propose a low-complexity decoding scheme that does not involve iterative message passing between the source and channel decoders; the low-complexity scheme performs only 1.08, 0.85, and 0.79 dB away from the theoretical limits at transmission rates of 1.0, 1.5, and 2.0 b/s, respectively.","Title: On Multiterminal Source Code Design\nYear: 2008\n\nAbstract: Multiterminal (MT) source coding refers to separate lossy encoding and joint decoding of multiple correlated sources. Recently, the rate region of both direct and indirect MT source coding in the quadratic Gaussian setup with two encoders was determined. We are thus motivated to design practical MT source codes that can potentially achieve the entire rate region. In this paper, we present two practical MT coding schemes under the framework of Slepian-Wolf coded quantization (SWCQ) for both direct and indirect MT problems. The first, asymmetric SWCQ scheme relies on quantization and Wyner-Ziv coding, and it is implemented via source splitting to achieve any point on the sum-rate bound. In the second, conceptually simpler scheme, symmetric SWCQ, the two quantized sources are compressed using symmetric Slepian-Wolf coding via a channel code partitioning technique that is capable of achieving any point on the Slepian-Wolf sum-rate bound. Our practical designs employ trellis-coded quantization and turbo/low-density parity-check (LDPC) codes for both asymmetric and symmetric Slepian-Wolf coding. Simulation results show a gap of only 0.139-0.194 bit per sample away from the sum-rate bound for both direct and indirect MT coding problems.","Title: Depth camera assisted multiterminal video coding\nYear: 2011\n\nAbstract: This paper addresses multiterminal video coding with the help of a low-resolution depth camera. In this setup, the depth sequence, together with the high-resolution texture sequences, are collected, compressed and transmitted separately to the joint decoder in order to obtain more accurate depth information and consequently better rate-distortion performance. At the decoder end, side information (for Wyner-Ziv coding) is generated based on successive refinement of the decompressed low-resolution depth map and texture frame warped from other terminals. Experimental results show sum-rate savings with the depth camera than without for the same PSNR performance. Comparisons to simulcast and JMVM coding are also provided. Although the sum-rate gain of our multiterminal video coding scheme (with or without the depth camera) over simulcast is relatively small, this work is the first that incorporates depth camera in a multiterminal setting.","Title: Fast algorithm for distortion-based error protection of embedded image codes.\nYear: 2005\n\nAbstract: We consider a joint source-channel coding system that protects an embedded bitstream using a finite family of channel codes with error detection and error correction capability. The performance of this system may be measured by the expected distortion or by the expected number of correctly decoded source bits. Whereas a rate-based optimal solution can be found in linear time, the computation of a distortion-based optimal solution is prohibitive. Under the assumption of the convexity of the operational distortion-rate function of the source coder, we give a lower bound on the expected distortion of a distortion-based optimal solution that depends only on a rate-based optimal solution. Then, we propose a local search (LS) algorithm that starts from a rate-based optimal solution and converges in linear time to a local minimum of the expected distortion. Experimental results for a binary symmetric channel show that our LS algorithm is near optimal, whereas its complexity is much lower than that of the previous best solution.","Title: Packet Erasure Protection for Multicasting\nYear: 2004\n\nAbstract: Priority encoding transmission is an efficient forward error correction system for the robust transmission of scalable image and video data over packeterasure networks. For a memoryless packet erasure channel we first study thesensitivity of an optimal protection solution to a change in the packet erasurerate and in the number of packets. We then propose a practical error protectionalgorithm for multicasting and broadcasting applications. Instead of computing an optimal solution for each client independently, we show that comparableresults can be obtained much faster by refining protections already computedfor other clients. We also consider the situation where clients share a bottleneck link and develop layered multiple description codes that provide a betterquality trade-off among all clients than previous solutions.","Title: An automatic and robust algorithm of reestablishment of digital dental occlusion.\nYear: 2010\n\nAbstract: In the field of craniomaxillofacial (CMF) surgery, surgical planning can be performed on composite 3-D models that are generated by merging a computerized tomography scan with digital dental models. Digital dental models can be generated by scanning the surfaces of plaster dental models or dental impressions with a high-resolution laser scanner. During the planning process, one of the essential steps is to reestablish the dental occlusion. Unfortunately, this task is time-consuming and often inaccurate. This paper presents a new approach to automatically and efficiently reestablish dental occlusion. It includes two steps. The first step is to initially position the models based on dental curves and a point matching technique. The second step is to reposition the models to the final desired occlusion based on iterative surface-based minimum distance mapping with collision constraints. With linearization of rotation matrix, the alignment is modeled by solving quadratic programming. The simulation was completed on 12 sets of digital dental models. Two sets of dental models were partially edentulous, and another two sets have first premolar extractions for orthodontic treatment. Two validation methods were applied to the articulated models. The results show that using our method, the dental models can be successfully articulated with a small degree of deviations from the occlusion achieved with the gold-standard method.","Title: Wavelet packets-based image coding using joint space-frequency quantization\nYear: 1994\n\nAbstract: A novel quantization scheme targeted at jointly optimizing the spatial and frequency characterization of the wavelet representation of images was introduced in Xiong et al. (1993) for image compression applications. The present authors extend the concept of joint space-frequency quantization (SFQ) to the more flexible class of wavelet packet representations (Coifman and Wickerhauser, 1992), which are a generalization of the multiresolution decomposition using the wavelet transform. They propose a fast algorithm to jointly search for the best wavelet packet basis and space-frequency quantizer, presenting empirical evidence of its high performance (e.g., for the “Barbara” image coded at 0.5 b/p, they get a 0.7 dB gain in PSNR over the fixed-wavelet based SFQ of Xiong et al. and 1.5 dB over Shapiro's embedded wavelet coder (Shapiro, 1993))","Title: Optimized error protection of scalable image bit streams [advances in joint source-channel coding for images\nYear: 2005\n\nAbstract: This article focuses on FEC for scalable image coders. For various channel models, we survey recent progress made in system design and discuss efficient source-channel bit allocation techniques, with emphasis on unequal error protection. This article considered JSCC (joint source-channel coding) at the application layer only. Recent research has studied cross-layer optimization where JSCC is appli...","Title: Layered Wyner-Ziv video coding.\nYear: 2006\n\nAbstract: Following recent theoretical works on successive Wyner-Ziv coding (WZC), we propose a practical layered Wyner-Ziv video coder using the DCT, nested scalar quantization, and irregular LDPC code based Slepian-Wolf coding (or lossless source coding with side information at the decoder). Our main novelty is to use the base layer of a standard scalable video coder (e.g., MPEG-4/H.26L FGS or H.263+) as the decoder side information and perform layered WZC for quality enhancement. Similar to FGS coding, there is no performance difference between layered and monolithic WZC when the enhancement bitstream is generated in our proposed coder. Using an H.26L coded version as the base layer, experiments indicate that WZC gives slightly worse performance than FGS coding when the channel (for both the base and enhancement layers) is noiseless. However, when the channel is noisy, extensive simulations of video transmission over wireless networks conforming to the CDMA2000 1X standard show that H.26L base layer coding plus Wyner-Ziv enhancement layer coding are more robust against channel errors than H.26L FGS coding. These results demonstrate that layered Wyner-Ziv video coding is a promising new technique for video streaming over wireless networks.","Title: On the Generalized Gaussian CEO Problem.\nYear: 2012\n\nAbstract: This paper considers a distributed source coding (DSC) problem where L encoders observe noisy linear combinations of K correlated remote Gaussian sources, and separately transmit the compressed observations to the decoder to reconstruct the remote sources subject to a sum-distortion constraint. This DSC problem is referred to as the generalized Gaussian CEO problem since it can be viewed as a generalization of the quadratic Gaussian CEO problem where the number of remote source K=1. First, we provide a new outer region obtained using the entropy power inequality and an equivalent argument (in the sense of having the same rate-distortion region and Berger-Tung inner region) among a certain class of generalized Gaussian CEO problems. We then give two sufficient conditions for our new outer region to match the inner region achieved by Berger-Tung schemes, where the second matching condition implies that in the low-distortion regime, the Berger-Tung inner rate region is always tight, while in the high-distortion regime, the same region is tight if a certain condition holds. The sum-rate part of the outer region is also studied and shown to meet the Berger-Tung sum-rate upper bound under a certain condition, which is obtained using the Karush-Kuhn-Tucker conditions of the underlying convex semidefinite optimization problem, and is in general weaker than the aforesaid two for rate region tightness.","Title: Optimal number of features as a function of sample size for various classification rules.\nYear: 2005\n\nAbstract: Given the joint feature-label distribution, increasing the number of features always results in decreased classification error; however, this is not the case when a classifier is designed via a classification rule from sample data. Typically (but not always), for fixed sample size, the error of a designed classifier decreases and then increases as the number of features grows. The potential downside of using too many features is most critical for small samples, which are commonplace for gene-expression-based classifiers for phenotype discrimination. For fixed sample size and feature-label distribution, the issue is to find an optimal number of features.Since only in rare cases is there a known distribution of the error as a function of the number of features and sample size, this study employs simulation for various feature-label distributions and classification rules, and across a wide range of sample and feature-set sizes. To achieve the desired end, finding the optimal number of features as a function of sample size, it employs massively parallel computation. Seven classifiers are treated: 3-nearest-neighbor, Gaussian kernel, linear support vector machine, polynomial support vector machine, perceptron, regular histogram and linear discriminant analysis. Three Gaussian-based models are considered: linear, nonlinear and bimodal. In addition, real patient data from a large breast-cancer study is considered. To mitigate the combinatorial search for finding optimal feature sets, and to model the situation in which subsets of genes are co-regulated and correlation is internal to these subsets, we assume that the covariance matrix of the features is blocked, with each block corresponding to a group of correlated features. Altogether there are a large number of error surfaces for the many cases. These are provided in full on a companion website, which is meant to serve as resource for those working with small-sample classification.For the companion website, please visit http://public.tgen.org/tamu/ofs/e-dougherty@ee.tamu.edu.","Title: Feasibility of interference neutralization in relay-aided MIMO interference broadcast channel with partial connectivity\nYear: 2013\n\nAbstract: In this paper, we study the feasibility of interference neutralization (IN) in partially connected relay-aided multi-input-multi-output (MIMO) interference broadcast channel (IBC), where each relay only communicates with users in the same cell. Due to partial connectivity, there is no need to exchange channel information among the relays in different cells. We first present the necessary and sufficient condition for IN feasibility using linear transceiver. We then provide the minimum relay configuration required to support the maximal number of data streams without interference. Finally, the achievable degrees-of-freedomregion is obtained.","Title: Normalization benefits microarray-based classification.\nYear: 2006\n\nAbstract: When using cDNA microarrays, normalization to correct labeling bias is a common preliminary step before further data analysis is applied, its objective being to reduce the variation between arrays. To date, assessment of the effectiveness of normalization has mainly been confined to the ability to detect differentially expressed genes. Since a major use of microarrays is the expression-based phenotype classification, it is important to evaluate microarray normalization procedures relative to classification. Using a model-based approach, we model the systemic-error process to generate synthetic gene-expression values with known ground truth. These synthetic expression values are subjected to typical normalization methods and passed through a set of classification rules, the objective being to carry out a systematic study of the effect of normalization on classification. Three normalization methods are considered: offset, linear regression, and Lowess regression. Seven classification rules are considered: 3-nearest neighbor, linear support vector machine, linear discriminant analysis, regular histogram, Gaussian kernel, perceptron, and multiple perceptron with majority voting. The results of the first three are presented in the paper, with the full results being given on a complementary website. The conclusion from the different experiment models considered in the study is that normalization can have a significant benefit for classification under difficult experimental conditions, with linear and Lowess regression slightly outperforming the offset method.","Title: Wyner-Ziv coding based on TCQ and LDPC codes\nYear: 2009\n\nAbstract: This paper considers trellis coded quantization (TCQ) and low-density parity-check (LDPC) codes for the quadratic Gaussian Wyner-Ziv coding problem. After TCQ of the source X, LDPC codes are used to implement Slepian-Wolf coding of the quantized source Q(X) with side information Y at the decoder. Assuming 256-state TCQ and ideal Slepian-Wolf coding in the sense of achieving the theoretical limit H(Q(X)|Y), we experimentally show that Slepian-Wolf coded TCQ performs 0.2 dB away from the Wyner-Ziv distortion-rate function DWZ(R) at high rate. This result mirrors that of entropy-constrained TCQ in classic source coding of Gaussian sources. Furthermore, using 8,192-state TCQ and assuming ideal Slepian-Wolf coding, our simulations show that Slepian-Wolf coded TCQ performs only 0.1 dB away from DWZ(R) at high rate. These results establish the practical performance limit of Slepian-Wolf coded TCQ for quadratic Gaussian Wyner-Ziv coding. Practical designs give performance very close to the theoretical limit. For example, with 8,192-state TCQ, irregular LDPC codes for Slepian-Wolf coding and optimal non-linear estimation at the decoder, our performance gap to DWZ(R) is 0.20 dB, 0.22 dB, 0.30 dB, and 0.93 dB at 3.83 bit per sample (b/s), 1.83 b/s, 1.53 b/s, and 1.05 b/s, respectively. When 256-state 4-D trellis-coded vector quantization instead of TCQ is employed, the performance gap to DWZ(R) is 0.51 dB, 0.51 dB, 0.54 dB, and 0.80 dB at 2.04 b/s, 1.38 b/s, 1.0 b/s, and 0.5 b/s, respectively.","Title: On packetization of embedded multimedia bitstreams\nYear: 2001\n\nAbstract: We study the problem of packetizing embedded multimedia bitstreams to improve the error resilience of source (compression) codes. This problem is important because of the increasing popularity of embedded compression methodology and its suitability for scalable streaming media over IP or/and mobile IP. We study various packetization schemes against packet erasure at both low and high bit rates. Maximizing packetization efficiency for embedded bitstreams is formulated as a discrete optimization problem and globally optimal packetization (OP) algorithms are proposed under different settings. Suboptimal packetization algorithms are also devised to reduce the complexity of the OP algorithms. In order to assess their effectiveness, the proposed packetization algorithms are used to packetize embedded image and video bitstreams with simulated packet loss. Experimental results show that our OP algorithms slightly outperforms suboptimal ones. In addition to confirming the superiority of the OP algorithms, these results also provide justification of heuristic packetization methods published in the literature","Title: Source-optimized irregular repeat accumulate codes with inherent unequal error protection capabilities and their application to scalable image transmission.\nYear: 2006\n\nAbstract: The common practice for achieving unequal error protection (UEP) in scalable multimedia communication systems is to design rate-compatible punctured channel codes before computing the UEP rate assignments. This paper proposes a new approach to designing powerful irregular repeat accumulate (IRA) codes that are optimized for the multimedia source and to exploiting the inherent irregularity in IRA codes for UEP. Using the end-to-end distortion due to the first error bit in channel decoding as the cost function, which is readily given by the operational distortion-rate function of embedded source codes, we incorporate this cost function into the channel code design process via density evolution and obtain IRA codes that minimize the average cost function instead of the usual probability of error. Because the resulting IRA codes have inherent UEP capabilities due to irregularity, the new IRA code design effectively integrates channel code optimization and UEP rate assignments, resulting in source-optimized channel coding or joint source-channel coding. We simulate our source-optimized IRA codes for transporting SPIHT-coded images over a binary symmetric channel with crossover probability p. When p = 0.03 and the channel code length is long (e.g., with one codeword for the whole 512 x 512 image), we are able to operate at only 9.38% away from the channel capacity with code length 132380 bits, achieving the best published results in terms of average peak signal-to-noise ratio (PSNR). Compared to conventional IRA code design (that minimizes the probability of error) with the same code rate, the performance gain in average PSNR from using our proposed source-optimized IRA code design is 0.8759 dB when p = 0.1 and the code length is 12800 bits. As predicted by Shannon's separation principle, we observe that this performance gain diminishes as the code length increases.","Title: A Multi-Level Design for Dirty-Paper Coding with Applications to the Cognitive Radio Channel.\nYear: 2011\n\nAbstract: We propose a close-to-capacity dirty-paper coding (DPC) framework that employs multi-level low density parity-check (LDPC) codes and trellis coded quantization. The proposed coding framework is robust in the sense that it performs close to capacity in both the high and the low rate regimes. This is in contrast to existing practical DPC schemes that perform well at either one of these regimes, but not both. In order to evaluate the performance of our scheme, we consider its application to a cognitive radio channel. At a block length of 2X10(5), the designed dirty-paper coding scheme operates within 0.6, 0.58 and 0.95 dB of the theoretical limit at transmission rates of 1.5, 1.0 and 0.5 bits/sample, respectively. To the best of our knowledge, this is the best performance reported in the literature so far.","Title: Feasibility Conditions for Interference Neutralization in Relay-Aided Interference Channel\nYear: 2014\n\nAbstract: Interference neutralization (IN) is a new interference management mechanism found from and inherent in interference networks with relays. In this paper, we study the feasibility of IN for relay-aided multi-input-multi-output (MIMO) interference broadcast channel (MIMO-IBC) without symbol extension. Assuming linear transceiver with multiple amplify-and-forward relays, we consider fully connected symmetric systems, where each base station (BS), relay, and user is equipped with multiple antennas, and each user desires multiple data streams. We first present the necessary condition of generalized IN, which is the proper condition to ensure interference-free transmission with linear transceivers for general relay-aided MIMO-IBC. We then find and prove the necessary and sufficient condition of the feasibility of coordinated IN and pure IN for a class of relay-aided MIMO-IBC, where the sufficiency is proved by constructing a full rank coefficient matrix of interference-free transmission equation with sub-matrices of special structures. We show that when each BS and user has the minimal antenna configuration for data transmission, the sufficient and necessary condition for coordinated IN is the same as the necessary condition for generalized IN. When there is an arbitrary number of antennas at the BSs and users, the derived sufficient conditions give rise to the minimum relay configuration required by the coordinated IN and pure IN to support a given number of data streams without interference. Our proof sheds lights on how to use the relay resources to neutralize the interference in an efficient way. The results are applicable for both relay-aided MIMO-IBC and relay-aided interference channel (MIMO-IC).","Title: Optimal Error Protection For Progressive Image Transmission Over Finite-State Markov Channels\nYear: 2003\n\nAbstract: This paper presents a unified framework for addressing progressive image transmission over both memoryless and fading channels based on finite-state Markov channel (FSMC) models. The main advantage of using FSMC models is that they allow analytical derivation of optimal joint source-channel coding solutions in the form of unequal error protection without the burden of simulating wireless channels. Our analyses and experiments confirm that 1) FSMC models work for fading channels and 2) PSNR results obtained with FSMC models compare favorably with those published in the literature.","Title: The effect of microarray image compression on expression-based classification\nYear: 2009\n\nAbstract: Current gene-expression microarrays carry enormous amounts of information. Compression is necessary for efficient distribution\n and storage. This paper examines JPEG2000 compression of cDNA microarray images and addresses the accuracy of classification\n and feature selection based on decompressed images. Among other options, we choose JPEG2000 because it is the latest international\n standard for image compression and offers lossy-to-lossless compression while achieving high lossless compression ratios on\n microarray images. The performance of JPEG2000 has been tested on three real data sets at different compression ratios, ranging\n from lossless to 45:1. The effects of JPEG2000 compression/decompression on differential expression detection and phenotype\n classification have been examined. There is less than a 4% change in differential detection at compression rates as high as\n 20:1, with detection accuracy suffering less than 2% for moderate to high intensity genes, and there is no significant effect\n on classification at rates as high as 35:1. The supplementary material is available at http://gsp.tamu.edu/web2/Compression.","Title: A Dirty-Paper Coding Scheme For The Cognitive Radio Channel\nYear: 2010\n\nAbstract: We implement a dirty-paper coded framework for the cognitive radio channel. We assume that the cognitive user has non-causal knowledge about the primary user's transmissions. Thus the secondary receiver can employ dirty-paper coding to counter the effect of any interference from the primary user. In addition, we consider a situation where the introduction of the cognitive user should not affect the performance of the primary system - nor should the primary system have to change its encoding/decoding process. For the primary user we use a low-density parity-check code and a 4-ary pulse amplitude modulation format. For the cognitive user, we propose a dirty-paper coding scheme which employs trellis-coded quantization as the source code and an irregular repeat-accumulate code as the channel code. At a transmission rate of 1.0 bits/sample, the designed dirty-paper coding scheme operates within 1.23 dB of the theoretical limit.","Title: Combined Source-Channel Coding of Images under Power and Bandwidth Constraints\nYear: 2007\n\nAbstract: Abstract This paper proposes a framework for combined source-channel coding for a power and bandwidth constrained noisy channel. The framework is applied to progressive image transmission using constant envelope -ary phase shift key ( -PSK) signaling over an additive white Gaussian noise channel. First, the framework is developed for uncoded -PSK signaling (with ). Then, it is extended to include coded -PSK modulation using trellis coded modulation (TCM). An adaptive TCM system is also presented. Simulation results show that, depending on the constellation size, coded -PSK signaling performs 3.1 to 5.2 dB better than uncoded -PSK signaling. Finally, the performance of our combined source-channel coding scheme is investigated from the channel capacity point of view. Our framework is further extended to include powerful channel codes like turbo and low-density parity-check (LDPC) codes. With these powerful codes, our proposed scheme performs about one dB away from the capacity-achieving SNR value of the QPSK channel.","Title: Slepian-Wolf Coded Nested Lattice Quantization for Wyner-Ziv Coding: High-Rate Performance Analysis and Code Design\nYear: 2006\n\nAbstract: Nested lattice quantization provides a practical scheme for Wyner-Ziv coding. This paper examines the high-rate performance of nested lattice quantizers and gives the theoretical performance for general continuous sources. In the quadratic Gaussian case, as the rate increases, we observe an increasing gap between the performance of finite-dimensional nested lattice quantizers and the Wyner-Ziv distortion-rate function. We argue that this is because the boundary gain decreases as the rate of the nested lattice quantizers increases. To increase the boundary gain and ultimately boost the overall performance, a new practical Wyner-Ziv coding scheme called Slepian-Wolf coded nested lattice quantization (SWC-NQ) is proposed, where Slepian-Wolf coding is applied to the quantization indices of the source for the purpose of compression with side information at the decoder. Theoretical analysis shows that for the quadratic Gaussian case and at high rate, SWC-NQ performs the same as conventional entropy-coded lattice quantization with the side information available at both the encoder and the decoder. Furthermore, a nonlinear minimum mean-square error (MSE) estimator is introduced at the decoder, which is theoretically proven to degenerate to the linear minimum MSE estimator at high rate and experimentally shown to outperform the linear estimator at low rate. Practical designs of one- and two-dimensional nested lattice quantizers together with multilevel low-density parity-check (LDPC) codes for Slepian-Wolf coding give performance close to the theoretical limits of SWC-NQ","Title: Progressive Source Coding for a Power Constrained Gaussian Channel\nYear: 2001\n\nAbstract: We consider the progressive transmission of a lossy source across a power constrained Gaussian channel using binary phase-shift keying modulation. Under the theoretical assumptions of infinite bandwidth, arbitrarily complex channel coding, and lossless transmission, we derive the optimal channel code rate and the optimal energy allocation per transmitted bit. Under the practical assumptions of a l...","Title: Progressive Video Delivery over Wideband Wireless Channels Using Space-Time Differentially Coded OFDM Systems\nYear: 2006\n\nAbstract: Progressive video delivery over wireless networks is very challenging due to the time-varying nature of wireless channels and limited power in the mobile devices. This paper proposes an end-to-end architecture for multilayer progressive video delivery over space-time differentially coded orthogonal frequency division multiplexing (STDC-OFDM) systems. An input video sequence is compressed by 3D-ESCOT into a layered bitstream. We input multiple layers of the bitstream in series to a STDC-OFDM channel. Different video source layers are protected by different error protection schemes in order to achieve unequal error protection. In progressive transmission, the reconstruction quality is important not only at the target transmission rate but also at the intermediate rates. So, the error protection strategy needs to optimize the average performance over the set of intermediate rates. We propose to use progressive joint source-channel coding to generate operational transmission distortion-rate (TD-R) functions and operational transmission distortion-power (TD-P) functions for multiple layers before forming the operational transmission distortion-power-rate (TD-PR) surfaces. Lagrange multipliers are then employed on the fly to obtain the optimal power allocation and optimal rate allocation among multiple layers, subject to constraints on the total transmission rate and the total power level. Progressive joint source-channel coding offers the scalability feature to handle bandwidth variations and changes in channel conditions. By extending the rate-distortion function in source coding to the TD-PR surface in joint source-channel coding, our work can use the \"equal slope” argument to effectively solve the transmission rate allocation problem as well as the transmission power allocation problem for multilayer video transmission. Experiments show that our scheme achieves significant improvement over a nonoptimal system with the same total power level and total transmission rate.","Title: Real-time unequal error protection for distortion-optimal progressive image transmission\nYear: 2003\n\nAbstract: For optimal progressive transmission of an embedded image code over a noisy channel, we consider an unequal error protection strategy that minimizes the average of the expected distortion over a set of intermediate rates. In contrast to previous work, we find a near-optimal solution in real-time. For a binary symmetric channel, two state-of-the-art source coders (SPIHT and JPEG200), and a rate-compatible punctured turbo coder as a channel coder, we compare our solution to the strategy that optimizes the end-to-end performance.","Title: Low-complexity encoding of binary quasi-cyclic codes based on Galois Fourier transform\nYear: 2013\n\nAbstract: This paper presents a novel low-complexity encoding algorithm for binary quasi-cyclic (QC) codes based on matrix transformation. First, a message vector is encoded into a transformed codeword in the transform domain. Then, the transmitted codeword is obtained from the transformed codeword by the inverse Galois Fourier transform. Moreover, a simple and fast mapping is devised to post-process the transformed codeword such that the transmitted codeword is binary as well. The complexity of our proposed encoding algorithm is less than ek(n-k)log2 e+ne(log22 e+log2 e)+ n/2 elog32 e bit operations for binary codes. This complexity is much lower than its traditional complexity 2e2(n - k)k. In the examples of encoding the binary (4095, 2016) and (15500, 10850) QC codes, the complexities are 12.09% and 9.49% of those of traditional encoding, respectively.","Title: Three-Dimensional Wavelet Coding of Video with Global Motion Compensation\nYear: 1999\n\nAbstract: Three-dimensional (2D+T) wavelet coding of video using SPIHT has been shown to outperform standard predictive video coders on complex high-motion sequences, and is competitive with standard predictive video coders on simple low-motion sequences. However, on a number of typical moderate-motion se- quences characterized by largely rigid motions, 3D SPIHT performs several dB worse than motion-compensated predictive coders, because it is does not take advantage of the real physical motion underlying the scene. In this paper, we introduce global motion compensation for 3D subband video coders, and find .5{2 dB gain on sequences with dominant background motion. Our approach is a hybrid of video coding based on sprites, or mosaics, and subband coding.","Title: Signal Processing for Multiterminal Communication Systems [from the Guest Editor]\nYear: 2007\n\nAbstract: The seven articles in this special section are devoted to multi-terminal communication systems that allow the transmission of multiple sources over multiple channels. The articles explore various signal processing aspects of these systems.","Title: Fast Trellis-Coded Color Quantization of Images\nYear: 2002\n\nAbstract: We examine color quantization of images using trellis-coded quantization (TCQ) in both the RGB domain and YUV domain. Together with a simple dithering scheme, an eight-bit trellis-coded color quantizer reproduces images that are visually indistinguishable from the 24-bit originals. It can be viewed as a predictive trellis-coded color quantization scheme. We also study trellis-coded vector quantization (TCVQ) for color quantization. Our proposed TCQ-based color quantization schemes are universal in the sense that no training or look-up table is needed. The complexity of TCQ is linear with respect to image size, making trellis-coded color quantization suitable for color printing, real-time interactive graphics and window-based display environment.","Title: A density evolution based framework for dirty paper code design using TCQ and multilevel LDPC codes\nYear: 2012\n\nAbstract: We propose a density evolution based dirty-paper code design framework that combines trellis coded quantization with multi-level low-density parity-check (LDPC) codes. Unlike existing design techniques based on Gaussian approximation and EXIT charts, the proposed framework tracks the empirically collected log-likelihood ratio (LLR) distributions at each iteration, and employs density evolution and differential evolution algorithms to design each LDPC component code. In order for the approximated LLR distributions obtained using density evolution to better match the true LLR distributions, a novel decorrelator is added to the decoder to make channel LLRs and check node LLRs almost independent of each other. Simulation results show that at 1 bit per sample transmission rate, the dirty-paper codes designed using the proposed method operate within 0.53 dB of the theoretical limit, reducing the best known result (with a 0.58 dB gap to the limit) by 0.05 dB at the same complexity and block length, while this improvement can be as large as 0.21 dB (corresponding to a 0.37 dB gap to the limit) when we use higher complexity encoder/decoder with longer block length.","Title: Lossy-to-lossless compression of medical volumetric data using three-dimensional integer wavelet transforms.\nYear: 2003\n\nAbstract: We study lossy-to-lossless compression of medical volumetric data using three-dimensional (3-D) integer wavelet transforms. To achieve good lossy coding performance, it is important to have transforms that are unitary. In addition to the lifting approach, we first introduce a general 3-D integer wavelet packet transform structure that allows implicit bit shifting of wavelet coefficients to approxi...","Title: A comparative study of DCT- and wavelet-based image coding\nYear: 1999\n\nAbstract: We undertake a study of the performance difference of the discrete cosine transform (DCT) and the wavelet transform for both image and video coding, while comparing other aspects of the coding system on an equal footing based on the state-of-the-art coding techniques. The studies reveal that, for still images, the wavelet transform outperforms the DCT typically by the order of about 1 dB in peak signal-to-noise ratio. For video coding, the advantage of wavelet schemes is less obvious. We believe that the image and video compression algorithm should be addressed from the overall system viewpoint: quantization, entropy coding, and the complex interplay among elements of the coding system are more important than spending all the efforts on optimizing the transform","Title: Error robust video transmission over wireless IP networks with multiuser detection\nYear: 2002\n\nAbstract: Error control and power allocation for transmitting wireless video over CDMA networks are considered in conjunction with multiuser detection. We map a layered video bitstream to several CDMA fading channels and inject multiple source/parity layers into each of these channels at the transmitter. At the receiver, we employ a linear minimum mean-square error (MMSE) multiuser detector in the uplink and two types of blind linear MMSE detectors in the downlink, for demodulating the received data. For given constraints on the available bandwidth and transmit power, the transmitter determines the optimal power allocation among different CDMA fading channels and the optimal number of source and parity packets to send that offer the best video quality. Simulation results show a performance gain of up to 3.5 dB with joint optimization over with rate optimization only.","Title: 3-D Face Recognition Based on Warped Example Faces\nYear: 2007\n\nAbstract: In this paper, we describe a novel 3-D face recognition scheme for 3-D face recognition that can automatically identify faces from range images, and is insensitive to holes, facial expression, and hair. In our scheme, a number of carefully selected range images constitute a set of example faces, and another range image is chosen as a ldquogeneric face.rdquo The generic face is then warped to match each of the example faces in the least mean square sense. Each such warp is specified by a vector of displacement values. In feature extraction operation, when a target face image comes in, the generic face is warped to match it. The geometric transformation used in the warping is a linear combination of the example face warping vectors. The coefficients in the linear combination are adjusted to minimize the root mean square error. After the matching process is complete, the coefficients of the composite warp are used as features and passed to a Mahalanobis-distance-based classifier for face recognition. Our technique is tested on a data set containing more than 600 range images. Experimental results in the access-control scenario show the effectiveness of the extracted features.","Title: Support-driven sparse coding for face hallucination\nYear: 2013\n\nAbstract: By incorporating the prior of positions, position patch based face hallucination methods can produce high-quality results and save computation time. Given a low-resolution face image, the key issue of these methods is how to encode the input low-resolution patch. However, due to stability and accuracy issues, the coding approaches proposed so far are not satisfactory. In this paper, we present a novel sparse coding method via exploiting the support information on the coding coefficients. In particular, the support information is characterized by the locality of the image patch manifold, which has been shown to be critical in data representation and analysis. According to the distances between the input patch and bases in the dictionary, we first assign different weights to the coding coefficients and then obtain the coding coefficients by solving a weighted sparse problem. Our proposed method exploits the non-linear manifold structure of patch samples and the sparse property of the redundant data, leading to stable and accurate representation. Experiments on commonly used databases demonstrate that our method outperforms state of the art.","Title: Wavelet image coding using trellis coded space-frequency quantization\nYear: 1998\n\nAbstract: The progress in wavelet image coding have brought the field into its maturity. Major developments in the process are rate-distortion (R-D) based wavelet packet transformation, zerotree quantization, subband classification and trellis-coded quantization, and sophisticated context modeling in entropy coding. Drawing from past experience and recent in sights, we propose a new wavelet image coding technique with trellis coded space-frequency quantization (TCSFQ). TCSFQ aims to explore space-frequency characterizations of wavelet image representations via R-D optimized zerotree pruning, trellis-coded quantization, and context modeling in entropy coding. Experiments indicate that the TCSFQ coder achieves twice as much compression as the baseline JPEG coder does at the same peak signal to noise ratio (PSNR), making it better than all other coders described in the literature.","Title: Progressive Image Transmission over Space-Time Coded OFDM-Based MIMO Systems with Adaptive Modulation\nYear: 2006\n\nAbstract: This paper considers a progressive image transmission system over wireless channels by combining joint source-channel coding (JSCC), space-time coding, and orthogonal frequency division multiplexing (OFDM). The BER performance of the space-time coded OFDM-based MIMO system based on a newly built broadband MIMO fading model is first evaluated by assuming perfect channel state information at the receiver for coherent detection. Then, for a given average SNR (hence, BER), a fast local search algorithm is applied to optimize the unequal error protection design in JSCC, subjected to fixed total transmitted energy for various constellation sizes. This design allows the measurement of the expected reconstructed image quality. With this end-to-end system performance evaluation, an adaptive modulation scheme is proposed to pick the constellation size that offers the best reconstructed image quality for each average SNR. Simulation results of practical image transmissions confirm the effectiveness of our proposed adaptive modulation scheme.","Title: Wavelet-based compression of M-FISH images.\nYear: 2005\n\nAbstract: Multiplex fluorescence in situ hybridization (M-FISH) is a recently developed technology that enables multi-color chromosome karyotyping for molecular cytogenetic analysis. Each M-FISH image set consists of a number of aligned images of the same chromosome specimen captured at different optical wavelength. This paper presents embedded M-FISH image coding (EMIC), where the foreground objects/chromo...","Title: Distributed Source Coding for Sensor Networks\nYear: 2004\n\nAbstract: In recent years, sensor research has been undergoing a quiet revolution, promising to have a significant impact throughout society that could quite possibly dwarf previous milestones in the information revolution. Realizing the great promise of sensor networks requires more than a mere advance in individual technologies. It relies on many components working together in an efficient, unattended, co...","Title: A new rate allocation scheme for progressive fine granular scalable coding\nYear: 2001\n\nAbstract: We examine the enhancement layer rate allocation problem in progressive fine granular scalable (PFGS) coding. The problem arises from the fact that different frames in the enhancement layer have different rates in PFGS coding. A joint operational rate-distortion (R-D) function for a multi-frame group is first established in enhancement layer PFGS coding, followed by experiments to verify its validity using real test sequences. The optimal rate allocation among frames in the group for the enhancement layer PFGS coding is then given based on the R-D function. Coding results show that, compared to uniform bit allocation, the new bit allocation scheme not only makes the quality variation in decoded video frames smoother, but also improves the coding efficiency of PFGS coding by up to 1.0 dxxB in PSNR. Furthermore, the new scheme has very low complexity, making it suitable for video multicast applications","Title: Cascaded differential and wavelet compression of chromosome images.\nYear: 2002\n\nAbstract: This paper proposes a new method for chromosome image compression based on an important characteristic of these images: the regions of interest (ROIs) to cytogeneticists for evaluation and diagnosis are well determined and segmented. Such information is utilized to advantage in our compression algorithm, which combines lossless compression of chromosome ROIs with lossy-to-lossless coding of the re...","Title: Microarray BASICA: background adjustment, segmentation, image compression and analysis of microarray images\nYear: 2004\n\nAbstract: This paper presents microarray BASICA: an integrated image processing tool for background adjustment, segmentation, image compression, and analysis of cDNA microarray images. BASICA uses a fast Mann-Whitney test-based algorithm to segment cDNA microarray images, and performs postprocessing to eliminate the segmentation irregularities. The segmentation results, along with the foreground and background intensities obtained with the background adjustment, are then used for independent compression of the foreground and background. We introduce a new distortion measurement for cDNA microarray image compression and devise a coding scheme by modifying the embedded block coding with optimized truncation (EBCOT) algorithm (Taubman, 2000) to achieve optimal rate-distortion performance in lossy coding while still maintaining outstanding lossless compression performance. Experimental results show that the bit rate required to ensure sufficiently accurate gene expression measurement varies and depends on the quality of cDNA microarray images. For homogeneously hybridized cDNA microarray images, BASICA is able to provide from a bit rate as low as 5 bpp the gene expression data that are Open image in new window % in agreement with those of the original 32 bpp images.","Title: Error-resilient unequal error protection of fine granularity scalable video bitstreams\nYear: 2006\n\nAbstract: This paper deals with the optimal packet loss protection issue for streaming the fine granularity scalable (FGS) video bitstreams over IP networks. Unlike many other existing protection schemes, we develop an error-resilient unequal error protection (ER-UEP) method that adds redundant information optimally for loss protection and, at the same time, cancels completely the dependency among bitstream after loss recovery. In our ER-UEP method, the FGS enhancement-layer bitstream is first packetized into a group of independent and scalable data packets. Parity packets, which are also scalable, are then generated. Unequal protection is finally achieved by properly shaping the data packets and the parity packets. We present an algorithm that can optimally allocate the rate budget between data packets and parity packets, together with several simplified versions that have lower complexity. Compared with conventional UEP schemes that suffer from bit contamination (caused by the bit dependency within a bitstream), our method guarantees successful decoding of all received bits, thus leading to strong error-resilience (at any fixed channel bandwidth) and high robustness (under varying and/or unclean channel conditions).","Title: Chromosome image enhancement using multiscale differential operators.\nYear: 2003\n\nAbstract: Chromosome banding patterns are very important features for karyotyping, based on which cytogenetic diagnosis procedures are conducted. Due to cell culture, staining, and imaging conditions, image enhancement is a desirable preprocessing step before performing chromosome classification. In this paper, we apply a family of differential wavelet transforms (Wang and Lee, 1998), (Wang, 1999) for this ...","Title: Edge-preserving interpolation for down/up sampling-based depth compression\nYear: 2012\n\nAbstract: Preserving the edges in depth compression is important for improving the synthesized view quality, this paper presents a novel edge-preserving depth up-sampling method for down/up sampling-based depth coding using both the texture and depth information. We take into account the edge similarity between depth maps and their corresponding texture images as well as the structural similarity among depth maps to build a weight model. Based on the weight model, the optimal MMSE up-sampling coefficients are estimated from the local covariance coefficients of the down-sampled depth map. Experimental results show that our proposed interpolation method for down/up sampling-based depth coding improves both the coding efficiency and synthesized view quality.","Title: Near-Capacity Dirty-Paper Code Design: A Source-Channel Coding Approach\nYear: 2009\n\nAbstract: This paper examines near-capacity dirty-paper code designs based on source-channel coding. We first point out that the performance loss in signal-to-noise ratio (SNR) in our code designs can be broken into the sum of the packing loss from channel coding and a modulo loss, which is a function of the granular loss from source coding and the target dirty-paper coding rate (or SNR). We then examine practical designs by combining trellis-coded quantization (TCQ) with both systematic and nonsystematic irregular repeat-accumulate (IRA) codes. Like previous approaches, we exploit the extrinsic information transfer (EXIT) chart technique for capacity-approaching IRA code design; but unlike previous approaches, we emphasize the role of strong source coding to achieve as much granular gain as possible using TCQ. Instead of systematic doping, we employ two relatively shifted TCQ codebooks, where the shift is optimized (via tuning the EXIT charts) to facilitate the IRA code design. Our designs synergistically combine TCQ with IRA codes so that they work together as well as they do individually. By bringing together TCQ (the best quantizer from the source coding community) and EXIT chart-based IRA code designs (the best from the channel coding community), we are able to approach the theoretical limit of dirty-paper coding. For example, at 0.25 bit per symbol (b/s), our best code design (with 2048-state TCQ) performs only 0.630 dB away from the Shannon capacity.","Title: Space-frequency quantization for a space-varying wavelet packet image coder\nYear: 1995\n\nAbstract: We introduce a new image coding algorithm which exploits the idea of space-varying wavelet packets, where the best filter bank representation is chosen from a large library. The filter bank tree representations in the library are free to vary in structure over different segments of the image, and a fast search algorithm is given. In addition we employ the idea of space-frequency quantization, which is a rate-distortion optimized extension of the zero-tree wavelet coder of Shapiro to wavelet packets. The coder thus adaptively chooses the representation to suit the image and adaptively chooses the quantization to suit the representation. We present coding results that confirm the excellent performance of the scheme","Title: A Low-Complexity Encoding of Quasi-Cyclic Codes Based on Galois Fourier Transform\nYear: 2013\n\nAbstract: The encoding complexity of a general (en,ek) quasi-cyclic code is O[(e^2)(n-k)k]. This paper presents a novel low-complexity encoding algorithm for quasi-cyclic (QC) codes based on matrix transformation. First, a message vector is encoded into a transformed codeword in the transform domain. Then, the transmitted codeword is obtained from the transformed codeword by the inverse Galois Fourier transform. For binary QC codes, a simple and fast mapping is required to post-process the transformed codeword such that the transmitted codeword is binary as well. The complexity of our proposed encoding algorithm is O[e(n-k)k] symbol operations for non-binary codes and O[ek(n-k)(log_2 e)] bit operations for binary codes. These complexities are much lower than their traditional counterpart O[(e^2)(n-k)k]. For example, our complexity of encoding a 64-ary (4095,2160) QC code is only 1.59% of that of traditional encoding, and our complexities of encoding the binary (4095, 2160) and (8176, 7154) QC codes are respectively 9.52% and 1.77% of those of traditional encoding. We also study the application of our low-complexity encoding algorithm to one of the most important subclasses of QC codes, namely QC-LDPC codes, especially when their parity-check matrices are rank deficient.","Title: Error robust scalable audio streaming over wireless IP networks\nYear: 2004\n\nAbstract: Streaming high-fidelity audio over wireless Internet protocol (IP) networks is a challenging task because the networks present not only packet losses, but also residual bit errors. These losses and errors have severe adverse effect on the compressed audio bitstream. To solve this problem, this paper introduces error resilience in conjunction with error protection for scalable audio streaming over wireless networks. Specifically, error resilience is achieved by performing bitstream data partitioning and reversible variable length coding in the audio coder. Error protection is provided by layered product channel code to simultaneously handle packet losses and residual bit errors. Both the row and column codes of the product code provide unequal error protection for different layers of the audio bitstream by considering the characteristics of the scalable audio. Rate-distortion optimization is performed to determine the best source-channel coding tradeoff that minimizes the average expected end-to-end distortion. Simulation results demonstrate the effectiveness of our proposed approach.","Title: Achieving the degrees of freedom of relay-aided interference broadcast channels\nYear: 2012\n\nAbstract: This paper studies the degrees of freedom (DoF) of relay-aided interference broadcast channels and the relay resource to achieve them. We show that, with the aid of half-duplex relays, a G-cell system can achieve GMBS/2 DoF, where MBS is the number of transmit antennas in each cell. By studying the interference-free constraints, we obtain a lower bound of the relay resource that ensures interference-free transmission. Instead of directly solving the complicated multivariate problem with cubic interference-free constraints, we propose to relax the problem to linear equations by randomly initiating certain variables, and derive an achievable bound on relay resource. Numerical results show that the relay-aided interference broadcast channels require less relay resource than relay-aided interference channels and transmission protocol has large impact on the required resources.","Title: Distributed Joint Source-Channel Coding of Video Using Raptor Codes\nYear: 2007\n\nAbstract: Extending recent works on distributed source coding, this paper considers distributed source-channel coding and targets at the important application of scalable video transmission over wireless networks. The idea is to use a single channel code for both video compression (via Slepian-Wolf coding) and packet loss protection. First, we provide a theoretical code design framework for distributed joint source-channel coding over erasure channels and then apply it to the targeted video application. The resulting video coder is based on a cross-layer design where video compression and protection are performed jointly. We choose Raptor codes - the best approximation to a digital fountain - and address in detail both encoder and decoder designs. Using the received packets together with a correlated video available at the decoder as side information, we devise a new iterative soft-decision decoder for joint Raptor decoding. Simulation results show that, compared to one separate design using Slepian-Wolf compression plus erasure protection and another based on FGS coding plus erasure protection, the proposed joint design provides better video quality at the same number of transmitted packets. Our work represents the first in capitalizing the latest in distributed source coding and near-capacity channel coding for robust video transmission over erasure channels.","Title: Audio coding and image denoising based on the nonuniform modulated complex lapped transform\nYear: 2005\n\nAbstract: Xiong and Malvar recently introduced a nonuniform modulated complex lapped transform (NMCLT) with good time-localization and controllable frequency resolution by using an oversampled nonuniform filter bank to generate its real and the imaginary components. In this paper, we first show that oversampling in the NMCLT is not necessary in theory but a by-product of fast implementation in practice. We also point out that the amount of oversampling, which can be flexibly controlled, depends on the application. We then describe in detail the implementation of the inverse transform, which was not addressed clearly by Xiong and Malvar. We present the first applications of the NMCLT to audio coding and image denoising. A scalable audio coder has been implemented by controlling the amount of oversampling and exploiting redundancy among the NMCLT coefficients via predictive coding. Experimental results show that the audio coder reduces pre-echoes and improves the sound quality of audio clips with transient sounds. A simple denoising algorithm based on the NMCLT has also been devised to provide images with better visual quality than those obtained with wavelet-based soft thresholding.","Title: Distributed joint source-channel coding of video\nYear: 2005\n\nAbstract: Based on recent works on source-channel coding for Wyner-Ziv coding, we consider the case with noisy channel in Wyner-Ziv coding and address distributed joint source-channel coding, while targeting at the important application of video transmission over packet erasure channels. The idea is to use a single channel code for both Slepian-Wolf coding (or source coding with side information at the decoder) and erasure protection. We choose Raptor codes - the best approximation to a digital fountain - for the targeted application and study both encoder and decoder designs under the new setting of distributed joint source-channel coding. Our work represents the first in capitalizing the latest in distributed source coding (e.g., Wyner-Ziv video coding) and near-capacity channel coding (e.g., fountain codes) for robust video transmission over erasure channels.","Title: Flexible tree-structured signal expansions using time-varying wavelet packets\nYear: 1997\n\nAbstract: Addresses the problem of finding the best time-varying filter bank tree-structured representation for a signal. The tree is allowed to vary at regular intervals, and the spacing of these changes can be arbitrarily short. The question of how to choose tree-structured representations of signals based on filter banks is considered. Wavelets and their adaptive version, known as wavelet packets, represent one approach that is popular. Wavelet packets are subband trees where the tree is chosen to match the characteristics of the signal. Variations where the tree varies over time have been proposed as the double tree and the time-frequency tree algorithms. Time-variation adds a further level of adaptivity. In all of the approaches proposed so far, the tree must be either fixed for the whole duration of the signal or fixed for its dyadic subintervals. The solution that we propose, as it allows more flexible variation, is an advance on the wavelet packet algorithm, the double tree algorithm, and the recently proposed time-frequency tree algorithm. Our solution is based on casting it in a dynamic programming (DP) setting. Focusing on compression applications, we use a Lagrangian cost of distortion +λ×rate as the objective function and explain our algorithm in detail, pointing out its relation to existing approaches to the problem. We demonstrate that the new algorithm indeed searches a larger library of representations than previously possible and that overcoming the constraint of dyadic time segmentations gives a significant improvement in practice","Title: Slepian-Wolf coded nested quantization (SWC-NQ) for Wyner-Ziv coding: performance analysis and code design\nYear: 2004\n\nAbstract: This paper examines the high-rate performance of low-dimensional nested lattice quantizers for the quadratic Gaussian Wyner-Ziv problem, using a pair of nested lattices with the same dimensionality. As the rate increases, the gap increases between the performances of low dimensional nested lattice quantizers and the Wyner-Ziv rate-distortion function. This gap is due to the relatively weak channel coding component (or coarse lattice) in the nested lattice pair. To enhance the lattice channel code and boost the overall performance, Slepian-Wolf coding is applied to the quantization indices to achieve further compression. Thereby a Wyner-Ziv coding paradigm is introduced using Slepian-Wolf coded nested lattice quantization (SWC-NQ). Theoretical analysis and simulation results show that, for the quadratic Gaussian source and at high rate, SWC-NQ performs the same as traditional entropy-constrained lattice quantization with side information available at both the encoder and decoder.","Title: Distributed Compression of Binary Sources Using Conventional Parallel and Serial Concatenated Convolutional Codes\nYear: 2003\n\nAbstract: We show how conventional parallel (turbo) and serial concatenated convolutionalcodes can be used to compress close to the Slepian-Wolf limit ofr correlated binarysources.Conventional refers to codes already used in channel coding.Focusing on the asymmetric case of compression of an equiprobable memoryless binary source withside information at the decoder, the approach is based on modeling the correlation asa channel and using syndromes.The encoding and decoding procedures are explainedin detail.The performance achieved is seen to be better than recently publishedresults using nonconventional turbo codes and very close to the Slepian-Wolf limit.","Title: Nested Turbo Codes for the Costa Problem.\nYear: 2007\n\nAbstract: Abstract—Driven by applications in data-hiding, MIMO broadcast channel coding, precoding for interference cancella- tion, and transmitter cooperation in wireless networks, Costa coding has lately become a very active research area. In this paper, we first offer code design guidelines in terms of source- channel coding for algebraic binning. We then address practical code design based on nested lattice codes and propose nested turbo codes using turbo-like trellis-coded quantization (TCQ) for source coding and turbo trellis-coded modulation (TTCM) for channel coding. Compared to TCQ, turbo-like TCQ offers structural similarity between the source and channel coding components, leading to more efficient nesting with TTCM and better source coding performance. Due to the difference in effective dimensionality between turbo-like TCQ and TTCM, there is a performance tradeoff between these two components when they are nested together, meaning that the performance of turbo-like TCQ worsens as the TTCM code becomes stronger and vice versa. Optimization of this performance tradeoff leads to our code design that outperforms existing TCQ/TCM and TCQ/TTCM constructions and exhibits a gap of 0.94, 1.42 and 2.65 dB to the Costa capacity at 2.0, 1.0, and 0.5 b/s, respectively. Index Terms—Costa coding, nested lattice codes, trellis-coded","Title: Wyner–Ziv Video Compression and Fountain Codes for Receiver-Driven Layered Multicast\nYear: 2007\n\nAbstract: The increasing popularity of video streaming applications that distribute data to a large number of clients motivates the design of reliable multimedia delivery systems capable of adapting to diverse transmission conditions. Receiver-driven layered multicast (RLM) efficiently addresses the issue of heterogeneity in clients' available bandwidths and packet loss rates by shifting rate control to the receiver side. We propose a system for RLM over the Internet and 3G wireless networks based on layered Wyner-Ziv video coding and digital fountain codes. Layered Wyner-Ziv video coding improves robustness to packet loss compared to current scalable video coders, such as MPEG-4 FGS coder, while generating a scalable output bit stream. Digital fountain codes are near-capacity erasure protection codes that are ideally suited for multicast applications due to their rateless property. By combining an error-resilient Wyner-Ziv video coder and rateless fountain codes, our system allows reliable video multicast to an arbitrary number of heterogeneous receivers without the requirement of feedback channels. Simulation results show performance improvements over a previous scheme that exploits multiple description and layered coding.","Title: Facial Feature Extraction from Range Images using a 3D Morphable Model\nYear: 2007\n\nAbstract: In this paper, a novel scheme is introduced for human facial feature extraction. Unlike previous methods that fit a 3D morphable model to 2D intensity images, our scheme utilizes 3D range images to extract features without requiring manually-defined initial landmark points. A linear transformation is used to achieve the mapping between the 3D model and a 3D range image, which makes the computation simple and fast. Moreover, our scheme is robust to the illumination and pose variations. In addition to features from range images, extra features can be obtained by examining optional 2D texture images. Using our scheme, we can also perform automatic eye/mouth corner localization. Experimental results show the high accuracy and robustness of our scheme.","Title: Reliable Versus Unreliable Transmission For Energy Efficient Transmission In Relay Networks\nYear: 2012\n\nAbstract: A network code is said to be reliable when all transmissions in the network are (deterministic) functions of the source messages; well-known examples include decode-forward for relay networks. It is said to be unreliable when transmissions depend on the noise realization at nodes; examples include compress-forward and amplify-forward. The deterministic capacity of a network is defined as the supremum of the rates achievable by reliable codes. In this paper we derive the deterministic capacity of some relay networks in the low power regime. The resulting energy per bit is then compared with the one achievable by arbitrary transmission.","Title: Compression of M-FISH images using 3-D ESCOT\nYear: 2001\n\nAbstract: This paper introduces a lossy to lossless coding technique for compression of multitarget fluorescence in situ hybridization (M-FISH) images using 3-D embedded subband coding with optimal truncation (3-D ESCOT) (Xu et al.). With a lifting-based integer wavelet decomposition, 3-D ESCOT achieves about twice as much compression as Lempel-Ziv (WinZip) coding-the current method for archiving M-FISH images. The lossy coding performance of 3-D ESCOT is significantly better than that of 2-D based JPEG-2000","Title: Memory-constrained 3-D wavelet transform for video coding without boundary effects\nYear: 2002\n\nAbstract: Three-dimensional (3-D) wavelet-based scalable video coding provides a viable alternative to standard MC-DCT coding. However, many current 3-D wavelet coders experience severe boundary effects across group of pictures (GOP) boundaries. This paper proposes a memory-efficient transform technique via lifting that effectively computes wavelet transforms of a video sequence continuously on the fly, thus eliminating the boundary effects due to limited length of individual GOPs. Coding results show that the proposed scheme completely eliminates the boundary effects and gives superb video playback quality.","Title: Low-Complexity Encoding of Quasi-Cyclic Codes Based on Galois Fourier Transform\nYear: 2014\n\nAbstract: This paper presents two novel low-complexity encoding algorithms for quasi-cyclic (QC) codes based on Galois Fourier transform. The key idea behind them is making use of the block diagonal structure of the transformed generator matrix. The first one, named encoding by Galois Fourier transform, is equivalent to the fast implementations of the traditional encoding by Galois Fourier transform. The second one, named encoding in the transform domain (ETD), requires much less computational complexity for encoding binary QC codes. It skips the first step of the first algorithm and applies post-processing to save a large number of Galois field multiplications. Its application to QC-LDPC codes is also studied in this paper. Particularly, the hardware cost of the ETD for RS-based LDPC codes can be greatly reduced by short linear-feedback shift registers.","Title: On the Minimum Energy of Sending Correlated Sources Over the Gaussian MAC\nYear: 2014\n\nAbstract: In this paper, we investigate the minimum energy of transmitting correlated sources over the Gaussian multiple-access channel. Compared to other works on joint source-channel coding, we consider the fundamental problem of the minimum transmission energy, where the source and channel bandwidths are not naturally matched. Different models of correlated sources are studied. We first treat lossy transmission of Gaussian sources, including multiterminal sources and CEO sources. We then consider lossless transmission of correlated binary sources. In all cases, we lower bound the minimum energy using a cut-set argument that couples transmission energy and the distortions for the Gaussian cases (or source entropy for the discrete case). For the achievable schemes, separate source and channel coding and uncoded transmission are studied as benchmarks. In addition, we show that hybrid digital/analog transmission achieves the best known energy efficiency.","Title: Multiterminal source coding: Theory, code design and applications\nYear: 2011\n\nAbstract: Summary form only given. Distributed source coding (DSC) considers the problem of separate compression and joint decompression of multiple correlated sources. Berger and Tung first introduced the multiterminal (MT) source coding problem and studied the region of all possible encoder rate tuples such that the sources are reconstructed under distortion constraints. One can loosely view MT source coding as the lossy version of Slepian-Wolf coding. Applications of MT source coding include distributed video sensor networks and MT/multiview video coding for camera arrays. Despite recent progresses, finding the sum-rate bound of quadratic Gaussian MT source coding with more than two terminals is still an open problem. In this talk, I will present our recent theoretical results on quadratic Gaussian MT source coding, limit-approaching code designs, and MT video coding (including the case with depth camera assistance).","Title: Multiresolutional encoding and decoding in embedded image and video coders\nYear: 1998\n\nAbstract: We address multiresolutional encoding and decoding within the embedded zerotree wavelet (EZW) framework for both images and video. By varying a resolution parameter, one can obtain decoded images at different resolutions from one single encoded bitstream, which is already rate scalable for EZW coders. Similarly one can decode video sequences at different rates and different spatial and temporal resolutions from one bitstream. Furthermore, a layered bitstream can be generated with multiresolutional encoding, from which the higher resolution layers can be used to increase the spatial/temporal resolution of the images/video obtained from the low resolution layer. In other words, we have achieved full scalability in rate and partial scalability in space and time. This added spatial/temporal scalability is significant for emerging multimedia applications such as fast decoding, image/video database browsing, telemedicine, multipoint video conferencing, and distance learning","Title: Achieving the degrees of freedom of 2×2×2 interference network with arbitrary antenna configurations\nYear: 2014\n\nAbstract: This paper studies the degrees of freedom (DoF) region of the 2 × 2 × 2 interference network, which is comprised of two sources, two relays and two destinations, each with arbitrary number of antennas. We prove that with linear transceivers, the cut-set outer bound can be achieved without any symbol extensions, except for one specific system setup, which has one-DoF gap to the cut-set bound. We show that to achieve the outer-bound, the transceivers include interference avoidance, cancelation, neutralization and alignment, depending on the antenna configuration.","Title: Nonlocal image denoising via collaborative spatial-domain LMMSE estimation\nYear: 2014\n\nAbstract: In recent years, the performance of image denoising has been boosted drastically by nonlocal algorithms and sparse coding techniques. In this paper, we also take a nonlocal approach to image denoising and formulate the problem as one of collaborative LMMSE estimation from grouped image patches. We show that our optimal LMMSE solution amounts to shrinking the singular values of the matrix representation of the grouped image patches. This interpretation of our solution allows us to relate our estimation-theoretic approach to other nonlocal algorithms and sparse coding techniques in the literature. In addition, we develop an iterative algorithm to find the best LMMSE estimate. Experimental results show that our proposed denoising algorithm achieves better PSNR and subjective performance than the state of the art.","Title: Depth-based human body enhancement in the infrared video\nYear: 2014\n\nAbstract: Based on the depth information acquired by the popular RGBD camera such as Kinect, the human body image areas in the infrared video can be selectively enhanced. In this paper, we firstly utilized the Optimal Contrast-Tone Mapping (OCTM) method instead of Histogram Equalization (HE) method to make a good contrast balance for the infrared video image acquired in a low illumination condition. Secondly, we used multiple iterations of the Level Set algorithm to improve the human body silhouette which initially recognized by the RGBD camera in each infrared frame. Finally, in order to improve the image quality of the human body area in each infrared frame, a fast bilateral filter had been employed to eliminate the spot noise while maintaining good edge features. Experimental results show that the proposed method can effectively enhance the human subjects in the infrared video images.","Title: Global motion compensation for low bitrate video coding\nYear: 1997\n\nAbstract: A global motion compensation (GMC) scheme is described and implemented for low bitrate coding. Experiments show that GMC gives excellent coding results. When coupled with the H.263 low bitrate video coding standard, GMC is capable of achieving up to 27% bitrate saving (or 1.8 dB gain in PSNR) for a high motion sequence such as Stefan. For a moderate motion sequence such as Cost-guard, we obtained an 8% bitrate saving over H.263 at the same quality using GMC","Title: Joint product code optimization for scalable multimedia transmission over wireless channels\nYear: 2002\n\nAbstract: State-of-the-art systems for the transmission of images over wireless channels generate an embedded bitstream and protect it with a product code where the row code is a concatenation of an outer cyclic redundancy check (CRC) code and an inner rate-compatible punctured convolutional (RCPC) code, and the column code is a Reed-Solomon (RS) code. In previous works, the product code was optimized by searching for the best RS protection for each RCPC code rate. We present a local search algorithm that jointly optimizes the RS and the RCPC codes. Experimental results show that our algorithm provides an approximately optimal solution, while its time complexity is much lower than that of the previous works.","Title: Compression of binary sources with side information at the decoder using LDPC codes\nYear: 2002\n\nAbstract: We show how low-density parity-check (LDPC) codes can be used to compress close to the Slepian-Wolf limit for cor- related binary sources. Focusing on the asymmetric case of com- pression of an equiprobable memoryless binary source with side information at the decoder, the approach is based on viewing the correlation as a channel and applying the syndrome concept. The encoding and decoding procedures are explained in detail. The per- formance achieved is seen to be better than recently published re- sults using turbo codes and very close to the Slepian-Wolf limit.","Title: Progressive trellis-coded space-frequency quantization for wavelet image coding\nYear: 2002\n\nAbstract: This paper addresses progressive wavelet image coding within the trellis-coded space-frequency quantization (TCSFQ) framework (Xiong et al., 1999). A method similar to that in Bilgin et al. (1999), is used to approximately invert TCSFQ when decoding at rates lower than the encoding rate. Our experiments show that the loss incurred for progressive transmission is within 1 dB in peak signal-to-noise ratio and that the progressive coding performance of TCSFQ is competitive with that of the celebrated SPIHT coder (Said et al., 1996) at all rates","Title: A distributed source coding technique for correlated images using turbo-codes\nYear: 2002\n\nAbstract: The Slepian-Wolf (1973) theorem states that the output of two correlated sources can be compressed to the same extent without loss, whether they communicate with each other or not, provided that decompression takes place at a joint decoder. We present a distributed source coding scheme for correlated images which uses modulo encoding of pixel values and encoding (compression) of the resulting symbols with binary and nonbinary turbo-codes, so that larger rate savings than using modulo encoding. alone are achieved, practically without loss.","Title: Joint source-channel coding of binary sources with side information at the decoder using IRA codes\nYear: 2002\n\nAbstract: We use systematic irregular repeat accumulate (IRA) codes as source-channel codes for the transmission of an equiprob- able memoryless binary source with side information at the de- coder. A special case of this problem is joint source-channel coding for a nonequiprobable memoryless binary source. The theoretical limits of this problem are given by combining the Slepian-Wolf theorem, the source entropy in the special case, with the channel capacity. The approach is based on viewing the correlation between the binary source output and the side information as a separate channel or an enhancement of the original channel. The joint source-channel encoding, decoding and code design procedures are explained in detail. The simulated performance results are better than the recently published solutions using turbo codes and very close to the theoretical limit.","Title: An efficient algorithm to find a jointly optimal time-frequency segmentation using time-varying filter banks\nYear: 1995\n\nAbstract: We examine the question of how to choose a time-varying filter bank representation for a signal which is optimal with respect to an additive cost function. We present in detail an efficient algorithm for the Haar filter set which finds the optimal basis, given the constraint that the time and frequency segmentations are binary. Extension to multiple dimensions is simple, and the use of arbitrary filter sets is also possible. We verify that the algorithm indeed produces a lower cost representation than any of the wavelet packet representations for compression of images using a simple rate-distortion cost.","Title: Adaptive transforms for image coding using spatially varying wavelet packets\nYear: 1996\n\nAbstract: We introduce a novel, adaptive image representation using spatially varying wavelet packets (WPs), Our adaptive representation uses the fast double-tree algorithm introduced previously (Herley et al., 1993) to optimize an operational rate-distortion (R-D) cost function, as is appropriate for the lossy image compression framework. This involves jointly determining which filter bank tree (WP frequency decomposition) to use, and when to change the filter bank tree (spatial segmentation). For optimality, the spatial and frequency segmentations must be done jointly, not sequentially. Due to computational complexity constraints, we consider quadtree spatial segmentations and binary WP frequency decompositions (corresponding to two-channel filter banks) for application to image coding. We present results verifying the usefulness and versatility of this adaptive representation for image coding using both a first-order entropy rate-measure-based coder as well as a powerful space-frequency quantization-based (SPQ-based) wavelet coder introduced by Xiong et al. (1993).","Title: On dualities in multiterminal coding problems\nYear: 2006\n\nAbstract: It has been shown recently that under certain conditions there exist dualities between different multiterminal (MT) source and channel coding problems. Following these results, we study lossless MT source coding and deterministic MT channel coding problems and point out different dualities between them. In particular, we show that there exists a functional duality between a Slepian-Wolf (SW) coding problem and a deterministic broadcast channel (DBC) coding problem and between a lossless multiple-description (MD) coding problem and a deterministic multiple-access channel (DMAC) coding problem. In analogy to the duality established between DBC and DMAC coding problems, we further propose a similar duality between SW and lossless MD coding problems; in this way, we form a closed \"duality loop\" of four MT coding problems, which imposes the existence of a single common rate point in the achievable rate regions of all four dual problems. We also consider duality in zero-error MT coding and shed light on practical code design with an example. Finally, extension to the case with only one lossless/deterministic component in the source/channel coding problem is provided.","Title: On Practical Design for Joint Distributed Source and Network Coding\nYear: 2009\n\nAbstract: This paper considers the problem of communicating correlated information from multiple source nodes over a network of noiseless channels to multiple destination nodes, where each destination node wants to recover all sources. The problem involves a joint consideration of distributed compression and network information relaying. Although the optimal rate region has been theoretically characterized, it was not clear how to design practical communication schemes with low complexity. This work provides a partial solution to this problem by proposing a low-complexity scheme for the special case with two sources whose correlation is characterized by a binary symmetric channel. Our scheme is based on a careful combination of linear syndrome-based Slepian-Wolf coding and random linear mixing (network coding). It is in general suboptimal; however, its low complexity and robustness to network dynamics make it suitable for practical implementation.","Title: On Outage Capacity in the Low Power Regime\nYear: 2012\n\nAbstract: This paper derives a formula for the wideband slope for outage capacity and consider its application to some specific wireless channels. For the broadcast channel, the formula indicates that superposition is always superior to time-division multiple access (TDMA). On the other hand, for the interference channel, we show that TDMA is better than superposition for most realistic situations.","Title: Rateless coded hybrid amplify/decode-forward cooperation for wireless multicast\nYear: 2012\n\nAbstract: We consider a cooperative wireless multicast channel with no channel state information available at the transmitters, and where all wireless links undergo independent identically distributed quasi-static Rayleigh fading. For cooperation, we propose a rateless coded approach and identify its benefits over a conventional fixed-rate two-hop strategy. In addition to providing robust communications under fading conditions, rateless coding is able to exploit the cooperation benefits to a greater degree. A hybrid rateless coded cooperation scheme is proposed which employs amplify-and-forward (AF) in conjunction with decode-and-forward (DF) strategy. Results based on Monte-Carlo simulations indicate that the rateless coded hybrid scheme is able to significantly outperform two-hop cooperation, as well as the individual AF and DF strategies.","Title: Outage capacity of the broadcast channel in the low power regime\nYear: 2010\n\nAbstract: We consider outage capacity in the broadcast channel when the base-station has none or little channel knowledge. We find the minimum energy per bit needed to achieve a certain outage probability and the corresponding wideband slope.","Title: Joint Slepian-Wolf/Dirty-paper coding\nYear: 2013\n\nAbstract: We consider a joint Slepian-Wolf/Dirty-paper coding (SW-DPC) setup where a binary source needs to be transmitted over an additive white-Gaussian channel in the presence of interference known only at the encoder, as well as correlated side-information available only at the decoder. We propose a practical joint SW-DPC framework that uses a single low-density parity-check code coupled with trellis coded quantization to simultaneously provide error protection (in the face of noise and interference) and compression (in the face of correlated side-information available at the decoder). Simulation results indicate that the proposed joint SW-DPC scheme with finite-length codes outperforms a scheme with separate SW and DPC by 0.3 dB. In addition, we show that our joint SW-DPC code designed for one set of channel conditions is capable of achieving negligible bit-error rates for many other channel conditions as well. More specifically, it achieves successful decoding for a wide variety of channel conditions for which a separation-based scheme fails.","Title: A distributed source coding technique for highly correlated images using turbo-codes\nYear: 2002\n\nAbstract: According to the Slepian-Wolf theorem [1], the output of two correlated sources can be compressed to the same extent without loss, no matter if they communicate with each other or not, provided that the decompression takes place at a common decoder having both compressed outputs available. In this paper, as an application of the Slepian-Wolf theorem, an advanced distributed source coding scheme for correlated images is presented. Assuming that the correlated image is a noisy version of the original, the scheme involves modulo encoding of the pixel values and encoding (compression) of the resulting symbols with binary and nonbinary turbo-codes, so that rate savings are achieved practically without loss.","Title: A Rateless Coded Protocol for Half-Duplex Wireless Relay Channels\nYear: 2011\n\nAbstract: We propose a rateless coded protocol for a half-duplex wireless relay channel where all links experience independent quasi-static Rayleigh fading and the instantaneous channel realizations are unavailable at the transmitters. We assume that the network does not have a stringent delay constraint-thus the source and/or the relay continue transmitting until the destination acknowledges successful decoding. We identify rateless coded relaying as the natural choice, where each transmission from the source and/or the relay adds incremental redundancy to help the destination recover the original message. Our proposed protocol utilizes, in conjunction with rateless coding, a combination of the two popular relay cooperation schemes, namely decode-forward and compress-forward. Assuming very limited feedback from the destination, we derive the theoretical performance bounds specifically with binary phase-shift keying. We then implement the rateless coded relaying protocol using Raptor codes. The degree profiles for the Raptor codes are designed to maximize the average throughput-with the design formulated as a convex optimization problem. Using discretized density evolution for asymptotically large block lengths, the optimized codes lose approximately 5% in performance from the theoretical limit, whereas with practical finite block lengths, the performance loss is approximately 9%.","Title: A New Sufficient Condition for Sum-Rate Tightness in Quadratic Gaussian Multiterminal Source Coding\nYear: 2010\n\nAbstract: This paper considers the quadratic Gaussian multiterminal (MT) source coding problem and provides a new sufficient condition for the Berger–Tung (BT) sum-rate bound to be tight. The converse proof utilizes a set of virtual remote sources given which the observed sources are block independent with a maximum block size of 2. The given MT source coding problem is then related to a set of two-terminal problems with matrix-distortion constraints, for which a new lower bound on the sum-rate is given. By formulating a convex optimization problem over all distortion matrices, a sufficient condition is derived for the optimal BT scheme to satisfy the subgradient-based Karush–Kuhn–Tucker condition. The subset of the quadratic Gaussian MT problem satisfying our new sufficient condition subsumes all previously known tight cases, and our proof technique opens a new direction for more general partial solutions.","Title: Matching Criterion between Source Statistics and Source Coding Rate\nYear: 2015\n\nAbstract: Joint source-channel coding (JSCC) based on double protograph low-density parity-check (DP-LDPC) codes has been shown to be a good solution for wireless communications. However, the premature error-floor region of DP-LDPC codes usually does not meet the bit error rate (BER) requirements. In this paper, we provide a matching criterion between the source statistics and source coding rate using a novel protograph extrinsic information transfer (PEXIT) algorithm with a new decoding threshold. The resulting matching criterion helps predict the error-floor region performance and give directions for source coding rate designs.","Title: On Maximum Linearly Achievable Degrees of Freedom Region of 2<formula formulatype=\"inline\"><tex Notation=\"TeX\">$\\,\\times\\,$</tex> </formula>2<formula formulatype=\"inline\"><tex Notation=\"TeX\">$\\,\\times\\,$</tex> </formula>2 Interference Network With Arbitrary Antenna Configurations\nYear: 2015\n\nAbstract: AbstractWe obtain the exact maximum Degrees of Freedom (DoF) region achieved by linear transceivers without symbol extensions of the 2 × 2 × 2 multiple-input multiple-output (MIMO) interference network, which is comprised of two sources, two relays and two destinations, each with arbitrary number of antennas. We prove that the maximum achievable DoF region for the networks under some antenna configurations coincide with the cut-set bound of the networks, while there is only one DoF gap from the bound for the networks under other configurations, which can not be bridged by linear transceivers. The basic idea of the proof is to construct a two-tier transceiver, where the first tier decomposes the general networks to several basic networks with special configurations, and the second tier achieves the maximal DoF tuples for these basic networks. A mechanism for constructing the second tier transceiver is proposed, which is referred to as channel scaling assisted interference elimination. Combined with interference avoidance at sources and interference cancelation at destinations depending on the antenna configurations, interference-free transmission can be ensured.","Title: Robust layered multiple description coding of scalable media data for multicast\nYear: 2005\n\nAbstract: Layered multiple description codes allow robust transmission of scalable media data over packet erasure networks, while providing simple rate adaptation and bandwidth savings for shared bottleneck links. We show how to efficiently design layered multiple description codes for multicast and broadcast applications in memoryless packet erasure networks. Our approach offers a significantly better qual...","Title: A fast depth map coding method based on optimized modes decision\nYear: 2015\n\nAbstract: Multiview video plus depth (MVD) has been widely used recently as the representation of 3D scenes. Due to the tremendous data volume, transmission of MVD sequences becomes difficult especially under networks circumstance. Hence, an efficient 3D video coding scheme is required to compress the video data. In this paper, a fast depth map coding method based on optimized inter-frame modes decision in H.264/AVC is proposed to improve the coding efficiency of depth maps. In our study, depth maps are divided into edge, foreground and background parts. For each part, the distribution of inter-frame modes is measured among sequences and only the most frequently used modes are selected as the candidate modes. Based on the statistic results, different modes decision strategies are applied to those three parts during coding process. Experiments show that the proposed method saves up to 76% coding time with negligible PSNR loss and bit rate overhead.","Title: A Real-Time Face Tracking System Based On A Single Ptz Camera\nYear: 2015\n\nAbstract: Conventional online education platforms implement a combination of static and PTZ (Pan-Tilt-Zoom) cameras which are not only costly but also require operators and high computational power. In this paper, we establish a real-time face tracking system based on a single PTZ camera with automatic operation as a cost effective solution. The proposed system takes into account the camera movement and network delays in the tracking algorithm design while maintaining cost and flexibility in practical implementation.","Title: An Interference Reduction Method Based On Reference Planes For Light-Coding Depth Cameras\nYear: 2015\n\nAbstract: Recently, light-coding depth cameras, with their relatively good performance, have been widely used for depth image generation. To extend the field of view, multiple depth cameras usually have to be employed for scene representation and reconstruction. However, the interference among multiple light-coding depth cameras degrades the quality of depth images significantly. In this paper, we present an interference reduction method based on reference planes for light-coding depth cameras. We characterize the mathematical model of pattern interference on each reference plane, and derive a method to extract depth values with the assistance of the reference planes. Experimental results show that our proposed method effectively reduces the interference caused by multiple light-coding based cameras.","Title: On the energy-delay tradeoff in lossy network communications\nYear: 2015\n\nAbstract: This work investigates the energy-delay tradeoff in real-time network communication systems with ARQ, where energy is measured by power and energy per bit, respectively. We consider the lossy communication case with a finite buffer size, where each block is allowed to be retransmitted under a time constraint. We apply finite blocklength results of channel coding into our system. By adaptively optimizing the blocklength, coding rate, power allocation, and maximum number of retransmissions according to the queue state, we algorithmically achieve the optimal energy-delay tradeoff. We also lower and upper bound the optimal energy-delay function in order to study its asymptotic behavior as the delay and buffer size go to infinity, showing consistency with existing result. That is: the energy per bit approaches the minimum of -1.59 dB as the delay goes to infinity and power approaches zero. We observe that the power increases very rapidly when delay moves away from infinity, meaning that it is very hard to achieve the -1.59 dB limit in practice.","Title: Sending Gaussian Multiterminal Sources Over The Gaussian Mac With Bandwidth Expansion\nYear: 2015\n\nAbstract: In this work, we investigate the minimum power of transmitting Gaussian multiterminal sources over the Gaussian multiple access channel (MAC) with bandwidth expansion. Distributed encoders observe the individual components of the multiterminal sources and attempt to describe them to a central decoder. Instead of assuming the sources and the channel have matched bandwidth, we consider the scenario when the transmission is subject to a bandwidth constraint in terms of the number of channel uses per source sample. We study the minimum transmission power such that the decoder can reconstruct the individual sources and meet the mean squared error (MSE) constraints on them. For any given bandwidth and distortion constraints, we optimize uncoded transmission to obtain an upper bound on the minimum transmission power. A hybrid coding scheme is then proposed to obtain a tighter upper bound.","Title: Distortion Minimization Via Adaptive Digital And Analog Transmission For Energy Harvesting-Based Wireless Sensor Networks\nYear: 2015\n\nAbstract: This paper studies wireless sensor networks with energy harvesting in which a transmitter collects the observed source signals from the sensors and send to a fusion center using the energy harvested from an ambient environment. The main objective is to minimize the distortion between the source signal observed by the sensors and that recovered by the fusion center. We introduce a novel adaptive transmission approach in which the transmitter can use either analog or digital transmission according to the dynamics of the energy harvesting process. We formulate the optimization problem as a Markov decision process (MDP) and derive the optimal policy that can minimize the long-term discounted distortion for the fusion center. Numerical results show that our proposed approach can significantly improve the network performance under different situations.","Title: Texture-free large-area depth recovery for planar surfaces\nYear: 2015\n\nAbstract: This paper presents a texture-free depth enhancement method for large-area depth recovery. The proposed algorithm identifies a large-area depth missing region, and iteratively segments its contour by setting different initial pixels in each iteration. Coordinate transformation is used to analyze the distribution of each contour segment. By examining distributions of all contour segments, statistical histogram analysis is applied in our approach to select contour pixels. Then, selected pixels are projected into the world coordinate system, and multiple linear regression is utilized for surface function approximation. Missing depth values of a large-area depth missing region can be recovered with guidance of the approximated surface function. Quantitative and qualitative evaluations over state-of-the-art depth enhancement methods demonstrate the effectiveness and superiority of our method. Being texture-free, the proposed method has the flexibility of being merged into traditional depth enhancement methods.","Title: Use of Non-Orthogonal Multiple Access in Dual-hop relaying.\nYear: 2016\n\nAbstract: To improve the sum-rate (SR) of the dual-hop relay system, a novel two-stage power allocation scheme with non-orthogonal multiple access (NOMA) is proposed. In this scheme, after the reception of the superposition coded symbol with a power allocation from the source, the relay node forwards a new superposition coded symbol with another power allocation to the destination. By employing the maximum ratio combination (MRC), the destination jointly decodes the information symbols from the source and the relay. Assuming Rayleigh fading channels, closed-form solution of the ergodic SR at high signal-to-noise ratio (SNR) is derived and a practical power allocation is also designed for the proposed NOMA scheme. Through numerical results, it is shown that the performance of the proposed scheme is significantly improved compared with the existing work.","Title: Performance Improvement of JSCC Scheme Through Redesigning Channel Code.\nYear: 2016\n\nAbstract: For joint source channel coding (JSCC) scheme based on double protograph low-density parity-check (DP-LDPC) codes, due to joint iterative decoding between the source and channel decoders, it is found that the optimal channel code in separate system is not optimal in joint system. In this letter, a novel joint protograph extrinsic information transfer analysis is proposed for the DP-LDPC system over AWGN and redesigning scheme for channel code is put forward to enhance the performance of DP-LPDC system. Both the EXIT analysis and the simulated results show the performance improvement of proposed systems. This verifies the viewpoint that the channel code should be redesigned for JSCC scheme even if the optimal channel codes are selected over AWGN in separate systems.","Title: The diversity of STF-coded MIMO-OFDM systems with a general correlation model.\nYear: 2016\n\nAbstract: Owing to insufficient antenna spaces, mobile scenarios, and multipaths in practice, transmission correlations in space, time, and frequency domains are inevitable in wireless communications. This paper studies the effect of general spatial, temporal, and frequency/path correlations on the performance of space-time-frequency (STF)-coded multiple-input, multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems over frequency-selective block-fading channels. Specifically, we first derive an upper bound on the maximum achievable diversity by Hadamard and tensor products and analyze the effect of general spatial, temporal, and frequency/path correlations on it using rank properties of block matrices. We then address STF code designs and give two examples, one traditional STF code and another quasi-SF code, to show that our upper bound on the maximum diversity is achievable. The decoding complexity is considered in the MIMO system with arbitrary correlated fading channels using the traditional STF code. We also identify the newly developed statistical channel models for MIMO LTE and 802.11n as special cases of our STF-coded MIMO-OFDM system by showing that our theoretical diversity results match those simulated from these statistical channel models. Finally, we show that our general diversity result recovers various maximum diversity gains for different special correlation scenarios that have appeared in the literature.","Title: Knowledge-Based Coding of Objects for Multisource Surveillance Video Data.\nYear: 2016\n\nAbstract: Global object redundancy (GOR), as opposed to local spatial/temporal redundancies in a single video clip, is a new form of redundancy common in multisource surveillance video data (MSVD). GOR is induced by the repetition of foreground objects across multiple cameras, and becomes influential as the number of objects increases. Eliminating GOR considerably improves MSVD coding efficiency. In an effort to accomplish this, this study first proposes a knowledge-based representation of objects based on careful analysis of GOR composition. The representation contains a constant part and a variational part: the former is used to represent the common knowledge shared by an object across multiple cameras, while the latter is used to represent local variations on the object's surfaces. Based on the proposed representation, a knowledge-based coding (KBC) method is then proposed in which each foreground object is encoded with a hybrid prediction scheme, where the constant part of the object is generated via global prediction from a model library and the variational part is predicted via local reference frames with pose-based, short-term prediction. Experimental results showed that the KBC method saves more than 39% bits on average for encoding foreground objects in high-resolution video clips (compared to 16% for the entire videos). Applying the proposed coding method to surveillance videos in large spatial and temporal scale allows storage savings at the PB level.","Title: A Novel Computer-Aided Surgical Simulation (CASS) System to Streamline Orthognathic Surgical Planning.\nYear: 2016\n\nAbstract: Orthognathic surgery is a surgical procedure to correct jaw deformities. It requires extensive presurgical planning. We developed a novel computer-aided surgical simulation (CASS) system, the AnatomicAligner, for doctors planning the entire orthognathic surgical procedure in computer following our streamlined clinical protocol. The computerized plan can be transferred to the patient at the time of surgery using digitally designed surgical splints. The system includes six modules: image segmentation and three-dimensional (3D) model reconstruction; registration and reorientation of the models to neutral head posture (NHP) space, 3D cephalometric analysis, virtual osteotomy, surgical simulation, and surgical splint designing. The system has been validated using the 5 sets of patient’s datasets. The AnatomicAligner system will be soon available freely to the broader clinical and research communities.","Title: Full-Duplex Machine-To-Machine Communication For Wireless-Powered Internet-Of-Things\nYear: 2016\n\nAbstract: This paper considers machine-to-machine (M2M) communication for wireless-powered Internet-of-Things (IoT) based networking systems. Motivated by the observation that transmitting signals generally requires more energy than receiving signals for most IoT-based systems, we study a special wireless-powered M2M communication system in which the receiver can send its surplus energy to the transmitter. We propose a framework of wireless powered full-duplex M2M communication (WP-FD-M2M) in which the energy transfer from the receiver to the transmitter and the data transmission from the transmitter to the receiver take place at the same time over the same frequency. We establish a stochastic game-based model, referred to as the M2M game, to characterize the interaction between autonomous M2M transmitter and receiver. We prove that, if the transmitter and receiver can sequentially optimize their data transmission and energy transfer based on the Markov strategy, it is possible to achieve the maximum long-term performance for M2M communication without a centralized controller or coordination between the transmitter and receiver. Numerical results show that our proposed approach can significantly improve the performance for M2M communication under various situations.","Title: Energy-Saving Predictive Resource Planning and Allocation.\nYear: 2016\n\nAbstract: Predictive resource allocation is an emerging approach to improve the performance of mobile systems as human behavior is reported predictable by leveraging big data analytics. Yet what information can be predicted by big data, what information need to be predicted for wireless access optimization, how to translate the information, and how to exploit the synthetic knowledge for allocating radio res...","Title: Optimal Caching and Scheduling for Cache-enabled D2D Communications.\nYear: 2017\n\nAbstract: To maximize offloading gain of cache-enabled device-to-device (D2D) communications, content placement and delivery should be jointly designed. In this letter, we jointly optimize caching and scheduling policies to maximize successful offloading probability, defined as the probability that a user can obtain desired file in local cache or via D2D link with data rate larger than a given threshold. We obtain the optimal scheduling factor for a random scheduling policy that can control interference in a distributed manner, and a low complexity solution to compute caching distribution. We show that the offloading gain can be remarkably improved by the joint optimization.","Title: Very Low-Resolution Face Recognition via Semi-Coupled Locality-Constrained Representation\nYear: 2016\n\nAbstract: Recognition tasks in very low-resolution (VLR) images are more challenging than those in high-resolution (HR) due to lack of adequate discriminative information. Previous VLR and HR coupled learning scheme limits both the representation and discriminative ability of features. In this work, we propose a semi-coupled locality-constrained representation (SLR) approach to learn the discriminative representations and the mapping relationship between VLR and HR features simultaneously. Both VLR and HR local manifold geometries are coded during representation, while the learned mapping function improves the manifold consistency by transforming VLR features to HR ones. Finally, the resolutionrobust features are fed into a sparse representation based classifier (SRC) to predict the face labels. The proposed algorithm gives better performance than many state-of-the-art VLR recognition algorithms.","Title: Two-Stage Power Allocation for Dual-Hop Relaying Systems With Non-Orthogonal Multiple Access.\nYear: 2017\n\nAbstract: To improve the sum-rate (SR) and the outage probability of the dual-hop relay system, a novel two-stage power allocation scheme with non-orthogonal multiple access is proposed. In this scheme, after the reception of the superposition coded symbol with a power allocation from the source, the relay decodes-and-forwards a new superposition coded symbol with another power allocation to the destination. By employing a simple linear combination, the destination jointly decodes the information symbols from the received signals from the source and the relay. Assuming Rayleigh fading channels, the ergodic SR and the outage performance of the system are investigated. In addition, a suboptimal power allocation strategy with closed form of the power allocation factors is also designed, which is close to the optimal one. Through numerical results, it is shown that the performance of the proposed scheme is significantly improved compared with the existing works.","Title: Robust Face Super-Resolution via Locality-Constrained Low-Rank Representation.\nYear: 2017\n\nAbstract: Learning-based face super-resolution relies on obtaining accurate a priori knowledge from the training data. Representation-based approaches (e.g., sparse representation-based and neighbor embeddingbased schemes) decompose the input images using sophisticated regularization techniques. They give reasonably good reconstruction performance. However, in real application scenarios, the input images are often noisy, blurry, or suffer from other unknown degradations. Traditional face super-resolution techniques treat image noise at the pixel level without considering the underlying image structures. In order to rectify this shortcoming, we propose in this paper a unified framework for representation-based face super-resolution by introducing a locality-constrained low-rank representation (LLR) scheme to reveal the intrinsic structures of input images. The low-rank representation part of LLR clusters an input image into the most accurate subspace from a global dictionary of atoms, while the locality constraint enables recovery of local manifold structures from local patches. In addition, low-rank, sparsity, locality, accuracy, and robustness of the representation coefficients are exploited in LLR via regularization. Experiments on the FEI, CMU face database, and real surveillance scenario show that LLR outperforms the state-of-the-art face super-resolution algorithms (e.g., convolutional neural network-based deep learning) both objectively and subjectively.","Title: Face Hallucination Using Deep Collaborative Representation For Local And Non-Local Patches\nYear: 2017\n\nAbstract: Patch-based face hallucination algorithms utilize either local patches (e.g., position-patch approaches) or nonlocal patches (e.g., dictionary-learning approaches) to exploit self-similarity prior from training samples. Although they yield decent results, solo source patches limit their performance due to not fully taking self-similarity prior from both local and nonlocal ones. In order to overcome this shortcoming, we propose a novel and efficient deep collaborative representation (DCR) based approach, to exploit both local and nonlocal self-similarity patches, for boosting face hallucination performance. First we learn a feature-inducing dictionary pair to represent local and nonlocal self-similarity prior, then deep (multiple-layer) representation weights and corresponding support dictionaries are iteratively updated to exploit accurate prior from coarse to fine. Finally, the high resolution (HR) output are optimized layer by layer. Experimental results outperform some state-of-the-art (e.g. Convolutional Neural Network based deep learning approach) which verify the validity of the proposed approach.","Title: Reliability-Oriented Decoding Strategy for LDPC Codes-Based D-JSCC System.\nYear: 2017\n\nAbstract: In this letter, a reliability oriented decoding strategy (RODS) for low density parity check codes-based distributed joint source and channel coding system is proposed. During each local decoding iteration, the reliability of each variable node is evaluated based on the sign of received log-likelihood ratios (LLRs) and its oscillation situation. Then, by employing reliability-oriented updating operation, the negative influence of those inaccurate messages is suppressed. Moreover, extra operations are performed on a group of most unreliable source nodes so that more accurate posteriori LLRs can be obtained. During global iteration, offset operation is performed to reduce error propagation. The simulation results illustrate that the proposed RODS outperforms other decoding algorithms at the aspects of error correction performance and convergence speed, especially when the correlation between distributed sources is low.","Title: Low-rank constrained collaborative representation for robust face recognition\nYear: 2017\n\nAbstract: Recently, sparse representation based classifiers (SRC) and collaborative representation based classifiers (CRC) have been shown to give very good performance under controlled scenarios. However, in practical applications, face recognition often encounters variations in illumination, expression, noise and occlusion, which cause severe performance degradation (due to the outliers in testing). In this paper, we present a novel robust face recognition algorithm based on class-wise low-rank constrained collaborative representations. We impose a low-rank constraint on the representation coefficient matrix to discriminate against outliers. The resulting low-rank constrained collaborative representation based classifier (LCRC) jointly minimizes the class-wise reconstruction error and rank of coefficient matrix. Experiments show that LCRC outperforms popular classifiers such as SRC, CRC, SVM, PROCRC on the AR, CMU PIE and LFW databases.","Title: Fault-tolerance based block-level bit allocation and adaptive RDO for depth video coding\nYear: 2017\n\nAbstract: Depth videos affect the visual quality of virtual view greatly, while conventional encoders are not adapted to encode depth videos. To solve this problem, we propose, in the paper, a fault-tolerance based joint block-level bit allocation scheme for depth video coding. The scheme classifies depth blocks into two classes by the fault-tolerance, and constructs virtual view perceptual quality based rate-distortion (R-D) model for each class. Based on the model, a joint block-level bit allocation scheme is proposed to obtain the optimized quantization parameter (QP) to encode each class of blocks. Further, an adaptive RDO algorithm is designed to determine λ\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">MODE</sub>\n, in order to achieve better visual quality of virtual views. Experimental results demonstrate that, compared with 3D-HEVC, the proposed method improves the visual quality of virtual views, especially at preserving details and boundaries of objects.","Title: Design, development and clinical validation of computer-aided surgical simulation system for streamlined orthognathic surgical planning.\nYear: 2017\n\nAbstract: There are many proven problems associated with traditional surgical planning methods for orthognathic surgery. To address these problems, we developed a computer-aided surgical simulation (CASS) system, the AnatomicAligner, to plan orthognathic surgery following our streamlined clinical protocol.","Title: Hevc-Based Compression Of High Bit-Depth 3d Seismic Data\nYear: 2017\n\nAbstract: In a previous work [1] we applied the idea of HEVC intra coding to compression of 32 b/p seismic images. Results are significantly better than those from a licensed commercial wavelet-based codec that is currently used at Shell for seismic image compression, which performs on par with JPEG-XR. Building upon [1], this paper exploits HEVC-based inter predictive coding for 3D 32 b/p seismic data. We propose a new model for the Lagrange multiplier in R-D optimization to accommodate 32 b/p bit-depth and extended quantization parameter range. We also focus on reducing the complexity of motion estimation to meet application needs. Experiments with our new codec show a 95% complexity reduction of encoding time at 10:1 compression ratio with only 1 dB loss on average PSNR. The compression performance and subjective quality of our codec received high evaluation marks from Shell geologists.","Title: Face Hallucination Using Region-Based Deep Convolutional Networks\nYear: 2017\n\nAbstract: Most deep learning based face hallucinations exploit random patch prior from training samples, then to learn the mapping functions between low-resolution (LR) and high-resolution (HR) images, and achieve satisfactory reconstruction performance. However, most of them do not take into account the prior information on facial structure, which is pivotal for face hallucination. Different from random patch prior based deep learning approaches, in this paper, we utilize facial structural prior and develop a simple yet powerful face hallucination, named region-based deep convolutional networks (RDCN). Firstly, we divide facial image into several regions of interest, then to train multiple parallel subnetworks of these regions for exacting better structure priors, finally HR output is reconstructed by stitching facial parts. Experiments on the FEI database demonstrate that the proposed region-based convolution networks outperform other state-of-the-art, including recently proposed deep learning based approaches, both in subjective and objective reconstruction qualities.","Title: A Noncoverage Field Model for Improving the Rendering Quality of Virtual Views.\nYear: 2018\n\nAbstract: Rendering quality optimization theory is one of the most basic and fascinating components of image-based rendering (IBR). The rendering quality of virtual views is related to the information in the source images. Capturing the image information depends on the geometric configuration of the camera (GCC) and, in particular, the positions and shooting directions of the cameras. Therefore, the rendering quality of virtual views can be improved by optimizing the GCC. This paper investigates the relationship between the GCC and the geometric configurations of the virtual view (GCVV). The influence of the GCC on the rendering quality is also analyzed. Based on the relationships among the GCC, GCVV, and rendering quality, a mathematical model of the noncoverage field (NCF) is proposed to quantify the rendering quality. The performance of the NCF is also analyzed using a set of GCVVs and GCCs. Furthermore, an optimization algorithm based on the NCF that simultaneously optimizes the position and direction of the GCC is presented. The proposed technique can be applied to obtain the optimal rendering quality of IBR for the linear case of camera positions and virtual views. Finally, experimental results are presented and compared with the theoretical results.","Title: Exploiting Residual Resources to Support High Throughput with Resource Allocation.\nYear: 2018\n\nAbstract: Residual radio resources are abundant in wireless networks due to dynamic traffic load, which can be exploited to support high throughput for serving non-real-time (NRT) traffic. In this paper, we investigate how to achieve this by resource allocation with predicted time-average rate, which can be obtained from predicted average residual bandwidth after serving real-time traffic and predicted average channel gains of NRT mobile users. We show the connection between the statistics of their prediction errors. We formulate an optimization problem to make a resource allocation plan within a prediction window for NRT users that randomly initiate requests, which aims to fully use residual resources with ensured quality of service (QoS). To show the benefit of knowing the contents to be requested and the request arrival time in advance, we consider two types of NRT services, video on demand and video on reservation. The optimal solution is obtained, and an online policy is developed that can transmit according to the plan after instantaneous channel gains are available. Simulation and numerical results validate our analysis and show a dramatic gain of the proposed method in supporting high arrival rate of NRT requests with given tolerance on QoS.","Title: AWCR: Adaptive and Weighted Collaborative Representations for Face Super-Resolution with Context Residual-Learning.\nYear: 2017\n\nAbstract: Owing to the ill-posed nature of the image super-resolution (SR) problem, learning-based approaches typically employ regularization terms in the representation. Current local-patch based face SR approaches weight representation coefficients to obtain adaptive and accurate priors. However, they ignore the fact that heteroskedasticity generally exists both in the observed data and representation coefficients. In this paper, we present a novel adaptive and weighted representation framework for face SR to further exploit adaptive and accurate prior information for different content inputs. Moreover, we enrich patch priors by sampling context patches, and learn the residual high-frequency components for better reconstruction performance. Experiments on the CAS-PEAL-R1 face database show that our proposed approach outperforms state-of-the-arts that include other deep learning based methods.","Title: Robust and efficient face recognition via low-rank supported extreme learning machine.\nYear: 2018\n\nAbstract: Recently, face recognition algorithms have made great progress in various real-world applications, e.g., authentication and criminal investigation. Deep-learning offers an end-to-end paradigm for vision recognition tasks and achieves good performance. However, designing and training the complex network architecture are time-consuming and labor-intensive. Moreover, under complex scenarios, illumination change, noise or occlusion in images degrade the performance of recognition algorithms. In order to ameliorate these issues, we propose an efficient three-layered low-rank supported extreme learning machine (LSELM) algorithm for face recognition which improves the recognition performance under complex scenarios with high efficiency. In the first layer, a given probe sample is clustered into certain training subspace as pre-clustering. In the second layer, with this subspace, a low-rank subspace of probe sample as robust feature which is insensitive to disguise, noise, variant expression or illumination will be recovered by low-rank decomposition. Furthermore, these low-rank discriminative features are coded to support training a forward neural network termed LSELM. Experimental results indicate that the proposed approach is on par with some deep-learning based face recognition algorithms on recognition performance but with less time complexity over some popular face datasets e.g., AR, Extend Yale-B, CMU PIE and LFW datasets.","Title: Enhanced Discriminative Generative Adversarial Network for Face Super-Resolution.\nYear: 2018\n\nAbstract: Recently, some generative adversarial network (GAN)-based super-resolution (SR) methods have progressed to the point where they can produce photo-realistic natural images by using a generator (G) and discriminator (D) adversarial scheme. However, vanilla GAN-based SR methods cannot achieve good reconstruction and perceptual fidelity on real-world facial images at the same time. Because of D loss, them are hard to converge stably, which may cause the model collapse. In this paper, we present an Enhanced Discriminative Generative Adversarial Network (EDGAN) for SR facial recognition to achieve better reconstruction and perceptual fidelities. First, we discover that a versatile D boosts the adversarial framework to a preferable Nash equilibrium. Then, we design the D via dense connections, which brings more stable adversarial loss. Furthermore, a novel perceptual loss function, by reusing the intermediate features of D, is used to eliminate the gradient vanishing problem of Gs. To our knowledge, this is the first framework to focus on improving the performance of the D. Quantitatively, experimental results show the advantages of EDGAN on two widely used facial image databases against the state-of-the-art methods with different terms. EDGAN performs sharper and realistic results on real-world facial images with large pose and illumination variations than its competitors.","Title: SLR: Semi-Coupled Locality Constrained Representation for Very Low Resolution Face Recognition and Super Resolution.\nYear: 2018\n\nAbstract: Although face recognition algorithms have been greatly successful recently, in real applications of very low-resolution (VLR) images, both super-resolution (SR) and recognition tasks are more challenging than those in high-resolution (HR) images. Given the rare discriminative information in VLR images, the one-to-many mapping relationship between HR and VLR images degrades the SR and recognition performances. In this paper, we propose a novel semi-coupled dictionary learning scheme to promote discriminative and representative abilities for face recognition and SR simultaneously by relaxing coupled dictionary learning. Specifically, we use semi-coupled locality-constrained representation to enhance the consistency between VLR and HR local manifold geometries, thereby overcoming the negative effects of one-to-many mapping. Given the learned task-oriented mapping function, we feed these discriminative features into a collaborative representation-based classifier to output their labels, and combine a locality-induced approach to hallucinate the HR images. Extensive experimental results demonstrate that the proposed approach outperforms a number of state-of-the-art face recognition and SR algorithms.","Title: iLDPC coded RCM scheme with optimised interleaver.\nYear: 2018\n\nAbstract: In this study, an irregular low-density parity-check (iLDPC) coded rate compatible modulation (iLDPC-RCM) is proposed. A particularly designed interleaver is inserted between LDPC and RCM such that a fast convergence and a low bit-error rate (BER) can be achieved. The combination of strong error correction capability of irregular LDPC code and the seamless adaptation of RCM enables the proposed sc...","Title: Interference Coordination and Resource Allocation Planning With Predicted Average Channel Gains for HetNets.\nYear: 2018\n\nAbstract: Future average channel gains are recently reported predictable within a minute-level horizon for a mobile user. Predictive resource allocation for non-realtime service with future average channel gains in a time window of one or more minutes long has been demonstrated effective in improving user experience and network throughput as well as reducing energy consumption. Nonetheless, existing studies for predictive resource allocation never consider inter-cell interference (ICI), which severely limits the user experience and network performance in densely-deployed cellular networks. This paper investigates predictive resource allocation in heterogeneous networks, where some base stations generate strong ICIs to some mobile users requesting non-realtime service. Optimizing the resource allocation in a predictive manner for interference networks is challenging, since how to allocate future resources depends on the future signal to interferenceplus-noise ratio, which in turn relies on the assigned resources. To deal with this difficulty, we introduce a predictive interference coordination scheme to divide all BSs and users into groups, where the BS-user pairs in each group can communicate simultaneously in a second-level frame. Then, we optimize a common resource allocation plan for all users in each group. The plan essentially determines which BSs in the group should be muted and the users should be associated with which active BS in each frame of the prediction window. By resorting to graph theory, we obtain the optimal solution and derive a low-complexity algorithm. Simulation results show that the proposed scheme outperforms existing relevant methods in terms of user satisfactory rate in heterogeneous networks with heavy traffic load.","Title: Jointly Optimizing User Association and BS Muting for Cache-Enabled Networks With Network-Coded Multicast and Reconstructed Interference Cancelation.\nYear: 2018\n\nAbstract: In this paper, we strive to improve the throughput of heterogeneous cellular networks by exploiting the pre-cached files at user end to manage interference. We consider a transmission scheme, where network-coded multicast is employed to help cancel multi-user interference, and reconstructed interference cancellation (RIC) is used to help eliminate inter-cell interference. Because RIC is opportunis...","Title: Augmented Reality Sandpit Simulating Ant Colonies\nYear: 2018\n\nAbstract: The way ants navigate their environment and forage for food is an intricate process. A common way ant species navigate is by using pheromone chemical trails leading to and from food sources. This paper summarizes an augmented reality sandpit project that aims to show the creation and evolution of these pheromone trails within a colony in an interactive way. A complex yet accessible simulation was built to allow users to move sand in a real sandpit while seeing virtually projected images on top of the sandpit change accordingly to showcase emergent ant colony behavior. A demo video of the project is available at https://www.youtube.com/watch?v=63Kx_xVEZkk.","Title: Group Embedding for Face Hallucination.\nYear: 2018\n\nAbstract: Face hallucination refers an application-specific super-resolution (SR) which predicts high-resolution images from one or multiple low-resolution inputs. Learning-based SR algorithms infer latent HR images by the guidance of coexisted priors from training samples. Various regularization methods have been successfully applied in face hallucination to ameliorate its ill-posed nature. But most of them only consider the local manifold geometry of a single patch which results in an unstable solution for SR reconstruction. In this paper, we propose a novel face hallucination algorithm to embed group patches for accurate prior representation and reconstruction. First, we select multiple recurrent self-similar patches to form a group embedding matrix. Then, a graph regularization term and another multiple-manifold regularization term are used to exploit accurate representation for SR performance. Our resulting ADMM algorithm gives a stable solution in an iterative manner. Furthermore, we use a two-step searching strategy for accelerated patch matching. Experimental results on the LFW database, FEI database, and some real-world images demonstrate the superiority of the proposed method when compared with state-of-the-art face hallucination results both on subjective and objective qualities.","Title: Document Verification: A Cloud-Based Computing Pattern Recognition Approach to Chipless RFID.\nYear: 2018\n\nAbstract: In this paper, we propose a novel means of verifying document originality using chipless RFID systems. The document sender prints a chipless RFID tag into the paper and does a frequency scanning in the 57-64 GHz spectrum of the document. The results of scattering parameters in individual step frequencies are stored in a cloud database, denoised and passed to pattern classifiers, such as support vector machines or ensemble networks. These supervised learners train themselves based on these data on the remote/cloud computer. The document receiver verifies this frequency fingerprint by using the same scanning method, sending the scattering parameters to the cloud server and getting the decoded data. Paper originality is verified if the decoded data are as expected. The advantages of our cloud chipless RFID processing deployments are cost reduction and increased security and scalability.","Title: Separability and Compactness Network for Image Recognition and Superresolution.\nYear: 2019\n\nAbstract: Convolutional neural networks (CNNs) have wide applications in pattern recognition and image processing. Despite recent advances, much remains to be done for CNNs to learn a better representation of image samples. Therefore, constant optimizations should be provided on CNNs. To achieve a good performance on classification, intuitively, samples' interclass separability, or intraclass compactness should be simultaneously maximized. Accordingly, in this paper, we propose a new network, named separability and compactness network (SCNet) to rectify this problem. SCNet minimizes the softmax loss and the distance between features of samples from the same class under a jointly supervised framework, resulting in simultaneous maximization of interclass separability and intraclass compactness of samples. Furthermore, considering the convenience and the efficiency of the cosine similarity in face recognition tasks, we incorporate it into SCNet's distance metric to enable sample features from the same class to line up in the same direction and those from different classes to have a large angle of separation. We apply SCNet to three different tasks: visual classification, face recognition, and image superresolution. Experiments on both public data sets and real-world satellite images validate the effectiveness of our SCNet.","Title: Channel Symmetry In Slepian-Wolf Code Design Based On Ldpc Codes With Application To The Quadratic Gaussian Wyner-Ziv Problem\nYear: 2004\n\nAbstract: We consider Slepian-Wolf code design (or source coding with side information) based on LDPC codes. We show that density evolution defined in conventional channel coding can be used in analyzing the Slepian-Wolf coding performance provided that certain symmetry condition, dubbed dual symmetry, is satisfied by the hypothetical channel between the source and the side information. Exploiting such an analysis, we design an efficient LDPC code based Slepian-Wolf coding scheme and apply it to the quadratic Gaussian Wyner-Ziv problems.","Title: Accurate Depth Extraction Method for Multiple Light-Coding-Based Depth Cameras.\nYear: 2017\n\nAbstract: Using multiple depth cameras can extend the field of view, which is beneficial to three-dimensional (3D) reconstruction. However, multiple active depth cameras would interfere with each other, which degrades the quality of depth images significantly. In this paper, we first present a depth extraction method based on sampling of the space at camera viewpoints to address the interference problem. Compared with the previous plane-sweeping method based on structured-light stereo and multiview stereo, depth images with less depth errors and better shape of objects are generated. Then, we analyze factors affecting depth accuracy for light-coding-based depth cameras and demonstrate the proposed depth extraction method also improves the accuracy of depth images by utilizing multiple projected patterns. Based on the analysis, subpixel-based matching (SPM) is finally applied to further improve the depth accuracy obtained by the depth extraction method. In the image matching process of our method, nearest neighbor interpolation is utilized to each projector's image plane to increase their resolution, which leads to the improved depth accuracy at subpixel level and avoids the drawbacks of changing parameters of light-coding-based depth cameras. Experimental results under simulated and real-world examples validate our analysis and show that the proposed method not only mitigates the impacts of interference effectively but also further improves the accuracy of depth images by using SPM.","Title: Deep Reinforcement Learning of Volume-Guided Progressive View Inpainting for 3D Point Scene Completion From a Single Depth Image\nYear: 2019\n\nAbstract: We present a deep reinforcement learning method of progressive view inpainting for 3D point scene completion under volume guidance, achieving high-quality scene reconstruction from only a single depth image with severe occlusion. Our approach is end-to-end, consisting of three modules: 3D scene volume reconstruction, 2D depth map inpainting, and multi-view selection for completion. Given a single depth image, our method first goes through the 3D volume branch to obtain a volumetric scene reconstruction as a guide to the next view inpainting step, which attempts to make up the missing information; the third step involves projecting the volume under the same view of the input, concatenating them to complete the current view depth, and integrating all depth into the point cloud. Since the occluded areas are unavailable, we resort to a deep Q-Network to glance around and pick the next best view for large hole completion progressively until a scene is adequately reconstructed while guaranteeing validity. All steps are learned jointly to achieve robust and consistent results. We perform qualitative and quantitative evaluations with extensive experiments on the SUNCG data, obtaining better results than the state of the art.","Title: Interference Range-Reduced Cooperative Multiple Access with Optimal Relay Selection for Large Scale Wireless Networks.\nYear: 2019\n\nAbstract: Cooperative communication improves the link throughput of wireless networks through spatial diversity. However, it reduces the frequency reuse of the entire network due to the enlarged link interference range introduced by each helper. In this paper, we propose a cooperative medium access control (MAC) protocol with optimal relay selection (ORS-CMAC) for multihop, multirate large scale networks, which can reduce the interference range and improve the network throughput. Then, we investigate the performance gain achieved by these two competitive factors, i.e., the spatial frequency reuse gain and spatial diversity gain, in large scale wireless networks. The expressions of maximum network throughput for direct transmissions and cooperative transmissions in the whole network are derived as a function of the number of concurrent transmission links, data packet length, and average packet transmission time. Simulation results validate the effectiveness of the theoretical results. The theoretical and simulation results show that the helper can reduce the spatial frequency reuse slightly, and spatial diversity gain can compensate for the decrease of the spatial frequency reuse, thereby improving the network throughput from the viewpoint of the whole network.","Title: Parallel Region-Based Deep Residual Networks for Face Hallucination.\nYear: 2019\n\nAbstract: Face hallucination is a super-resolution algorithm specially designed to improve the resolution and quality of low-resolution (LR) input face images. Although a deep neural network offers an end-to-end mapping from LR to high-resolution (HR) images, most of the deep learning-based face hallucinations neglect the structure prior for face images. To utilize the highly structured facial prior, a parallel region-based deep residual network (PRDRN) was developed to predict the missing detailed information for accurate image reconstruction. Initially, the image is divided into multiple regions with the symmetry of face structures. Then, the sub-networks corresponding to multiple regions are trained in parallel. Finally, all reconstructed regions are combined to form the HR image. The experimental results on FEI, CASIA-Webface and CMU-MIT public face databases show that the proposed network outperforms other state-of-the-art approaches.","Title: An Improved Stereo Matching Algorithm For Vehicle Speed Measurement System Based On Spatial And Temporal Image Fusion\nYear: 2021\n\nAbstract: This paper proposes an improved stereo matching algorithm for vehicle speed measurement system based on spatial and temporal image fusion (STIF). Firstly, the matching point pairs in the license plate area with obviously abnormal distance to the camera are roughly removed according to the characteristic of license plate specification. Secondly, more mismatching point pairs are finely removed according to local neighborhood consistency constraint (LNCC). Thirdly, the optimum speed measurement point pairs are selected for successive stereo frame pairs by STIF of binocular stereo video, so that the 3D points corresponding to the matching point pairs for speed measurement in the successive stereo frame pairs are in the same position on the real vehicle, which can significantly improve the vehicle speed measurement accuracy. LNCC and STIF can be used not only for license plate, but also for vehicle logo, light, mirror etc. Experimental results demonstrate that the vehicle speed measurement system with the proposed LNCC+STIF stereo matching algorithm can significantly outperform the state-of-the-art system in accuracy.","Title: Robust Vehicle Speed Measurement Based On Feature Information Fusion For Vehicle Multi-Characteristic Detection\nYear: 2021\n\nAbstract: A robust vehicle speed measurement system based on feature information fusion for vehicle multi-characteristic detection is proposed in this paper. A vehicle multi-characteristic dataset is constructed. With this dataset, seven CNN-based modern object detection algorithms are trained for vehicle multi-characteristic detection. The FPN-based YOLOv4 is selected as the best vehicle multi-characteristic detection algorithm, which applies feature information fusion of different scales with both rich high-level semantic information and detailed low-level location information. The YOLOv4 algorithm is improved by combing with the attention mechanism, in which the residual module in YOLOv4 is replaced by the ECA channel attention module with cross channel interaction. An improved ECA-YOLOv4 object detection algorithm based on both feature information fusion and cross channel interaction is proposed, which improves the performance of YOLOv4 for vehicle multi-characteristic detection and reduces the model parameter size and FLOPs as well. A multi-characteristic fused speed measurement system based on license plate, logo, and light is designed accordingly. The system performance is verified by experiments. The experimental results show that the speed measurement error rate of the proposed system meets the requirement of the China national standard GB/T 21555-2007 in which the speed measurement error rate should be less than 6%. The proposed system can efficiently enhance the vehicle speed measurement accuracy and effectively improve the vehicle speed measurement robustness.","Title: Trajectory is not Enough: Hidden Following Detection\nYear: 2021\n\nAbstract: ABSTRACTIn outdoor crimes such as robbery and kidnapping, suspects generally secretly follow their victims in public places and then look for opportunities to commit crimes. Video anomaly detection (VAD) has achieved fruitful results through deep neural networks (DNN). However, as an abnormal behavior without obvious abnormal physical features, hidden following is highly similar to ordinary walking and accompanying behaviors, so it is difficult to effectively detect hidden dangerous followers using video anomaly detection methods or traditional trajectory analysis methods. We propose \"hidden follower'' detection (HFD) task and a HFD model based on gaze pattern extraction. It extracts gaze pattern features of pedestrians from gaze-interval-series and introduces a time series classification model to classify pedestrians with or without hidden following purposes. Based on this model, we propose a hidden follower detection framework (HFDF) to detect hidden followers from normal pedestrians, which utilizes the trajectories and gaze patterns extracted from videos. To cope with the lack of test data, we construct a dataset of 1200 pedestrians from the crowd simulation model to simulate scenes including hidden followers, and we also collected a surveillance video dataset including the hidden following behaviors. The experiments conducted on these two datasets show that HFDF can consistently outperform the state-of-the-art method by a notable margin in the HFD task on the commonly-used F1 benchmark.","Title: Rethinking Lightweight: Multiple Angle Strategy for Efficient Video Action Recognition\nYear: 2022\n\nAbstract: Video action recognition task involves modeling spatiotemporal information, and efficiency is critical to capture spatiotemporal dependencies in the video. Most existing models rely on optical flow information to capture the dynamic visual tempos between consecutive video frames. Although impressive performance can be achieved by combining optical flow with RGB, the time-consuming nature of optical flow computation cannot be ignored. Moreover, 3D CNN has successfully modeled spatiotemporal information, yet the enormous computational volume is unsuitable for real-time action recognition. In this letter, we propose a novel lightweight video feature extraction strategy that achieves better recognition performance with lower FLOPs. In particular, we perform convolution on the video cube from three orthogonal angles to learn its appearance and motion features. Compared with the computational volume of 3D CNN, our proposed method is more economical and thus meets the lightweight requirements. Extensive experimental results on public Something Something-V1&V2 and Diving48 datasets show our approach achieves the state-of-the-art performance.","Title: Real and Pseudo Pedestrian Detection Method with CA-YOLOv5s Based on Stereo Image Fusion\nYear: 2022\n\nAbstract: With the development of convolutional neural networks, the effect of pedestrian detection has been greatly improved by deep learning models. However, the presence of pseudo pedestrians will lead to accuracy reduction in pedestrian detection. To solve the problem that the existing pedestrian detection algorithms cannot distinguish pseudo pedestrians from real pedestrians, a real and pseudo pedestrian detection method with CA-YOLOv5s based on stereo image fusion is proposed in this paper. Firstly, the two-view images of the pedestrian are captured by a binocular stereo camera. Then, a proposed CA-YOLOv5s pedestrian detection algorithm is used for the left-view and right-view images, respectively, to detect the respective pedestrian regions. Afterwards, the detected left-view and right-view pedestrian regions are matched to obtain the feature point set, and the 3D spatial coordinates of the feature point set are calculated with Zhengyou Zhang's calibration method. Finally, the RANSAC plane-fitting algorithm is adopted to extract the 3D features of the feature point set, and the real and pseudo pedestrian detection is achieved by the trained SVM. The proposed real and pseudo pedestrian detection method with CA-YOLOv5s based on stereo image fusion effectively solves the pseudo pedestrian detection problem and efficiently improves the accuracy. Experimental results also show that for the dataset with real and pseudo pedestrians, the proposed method significantly outperforms other existing pedestrian detection algorithms in terms of accuracy and precision.","Title: Spatiotemporal two-stream LSTM network for unsupervised video summarization\nYear: 2022\n\nAbstract: Within user-created videos, the constantly changing content among neighboring images brings more challenge for the prior video summarization methods. Assuming the images' critical features are refined, one can obtain promising accuracy of keyframes' selection which is key in video summarization. In our work, we innovatively proposed a Spatiotemporal two-stream LSTM network-based (ST-LSTM) model to enhance the images' critical features with the combination of spatial saliency and temporal semantic dependencies which is referred to as the two-stream method. Motivated by the fact that sizable and moving objects attract more visual attention, we newly design a Saliency-area-based attention network to filter irrelative non-attractive information. We use the latest attention-based Bi-LSTM network to extract the temporal dependency on the semantic features. Furthermore, a multi-feature-based reward function is presented to reinforce the ST-LSTM model by integrating diversity, representativeness, and storyness. Last, the Deep Deterministic Policy Gradient (DDPG) algorithm is adopted to do the unsupervised training for the proposed method. Extensive experiments on the public datasets demonstrate that our method outperforms the state-of-the-art."],"string":"[\n \"Title: Lossy-to-lossless ROI coding of chromosome images using modified SPIHT and EBCOT\\nYear: 2002\\n\\nAbstract: This paper proposes a lossy-to-lossless region of interest (ROI) compression scheme based on set partitioning in hierarchical trees (SPIHT) [I] and embedded block coding with optimized truncation (EBCOT) [2] (EBCOT is the base of the JPEG-2000 [3] standard). However, SPIHT does not support ROI coding and JPEG-2000 does not allow lossy-to-lossless ROI compression. For our application, we modify the original SPIHT and EBCOT algorithms for lossy-to-lossless ROI coding of both the foreground and the background of chromosome images. Experiments show that our implementations offer better compression performance with exact ROI support than other image coders.\",\n \"Title: Cooperation in the low power regime for the MAC using multiplexed rateless codes\\nYear: 2010\\n\\nAbstract: In this paper, we consider cooperation in the low power (low SNR) regime for the multiple access channel with the assumption that the transmitters have no channel state information. A relevant performance measure to consider is therefore the outage capacity. We develop cooperation methods based on multiplexed coding in conjunction with rateless codes and find the achievable rates and in particular the minimum energy per bit required to achieve a certain outage probability. We consider two modes of operation: full duplex [code-division multiple access (CDMA)], where nodes can transmit and receive simultaneously on the same frequency hand, and half duplex [frequency-division multiple access (FDMA)], where the nodes transmit and listen on different frequency bands. We show that, perhaps surprisingly, there is little loss in performance when using FDMA. Furthermore, our results show that multiplexed rateless codes come within 0.1 dB of the outer bound on capacity. We also develop practical rateless coding methods for FDMA using multiplexed Raptor codes which operate within 0.52 and 1.1 dB of the theoretical limit for the two- and four-user case, respectively.\",\n \"Title: Witsenhausen–Wyner Video Coding\\nYear: 2011\\n\\nAbstract: Inspired by Witsenhausen and Wyner's 1980 (now expired) patent on “interframe coder for video signals,” this paper presents a Witsenhausen-Wyner video codec, where the motion-compensated previously decoded video frame is used at the decoder as side information for joint decoding. Specifically, we replace predictive Inter coding in H.264/AVC by the syndrome-based coding scheme of Witsenhausen and Wyner, while keeping the Intra and Skip modes of H.264/AVC unchanged. We employ forward motion estimation at the encoder and send the motion vectors to help generate side information at the decoder, since our focus is not on low-complexity encoding. We also examine the tradeoff between the motion vector resolution and coding efficiency. Within the Witsenhausen-Wyner coding mode, we optimize the decision between syndrome coding and entropy coding among different discrete cosine transform (DCT) bands and among different bit-planes within each DCT coefficient. Extensive simulations of video transmission over wireless networks show that Witsenhausen-Wyner video coding is more robust against channel errors than H.264/AVC. The price paid for enhanced error-resilience with Witsenhausen-Wyner coding is a small loss in compression efficiency.\",\n \"Title: Nested convolutional/turbo codes for the binary Wyner-Ziv problem\\nYear: 2003\\n\\nAbstract: ABSTRACT We show how,concatenated (convolutional) codes can be used to compress,close to the Wyner-Ziv limit for binary sources. Focusing on the case of lossy compression,of an equiprobable memoryless,binary source with side informa- tion at the decoder, the approach is based on nested bi- nary linear codes, which is the extension of Wyner’s lossless compression scheme to the lossy case proposed by Shamai, Verdu and Zamir. Based on our previous work on loss- less compression with concatenated codes, we are able to combine,the only two previously suggested nested schemes into a novel turbo scheme,with improved performance. Our scheme can come within 0.09 bits from the theoretical limit, which to our knowledge,is the first result ever reported for the binary Wyner-Ziv problem.\",\n \"Title: Iterative decoding of differentially space-time coded multiple descriptions of images\\nYear: 2003\\n\\nAbstract: We consider transporting images over wireless fading channels rather than the on-off channels considered in most works related to multiple description (MD) coding. The new idea is to use iterative (turbo) decoding techniques developed for serially concatenated coding systems to improve the performance of the receiver in successive decoding iterations. We treat MD coding, realized by embedded image coding plus unequal error protection (e.g., product code structure), as the outer constituent code and use a differential space-time code as the inner constituent code. Experimental results show that our iterative scheme can effectively improve the system performance. Furthermore, most of the gain in PSNR is achieved with only one iteration in the low SNR range, e.g., 0-20 dB.\",\n \"Title: Multiuser resource allocation for video transmission over a chip-interleaved multicarrier system\\nYear: 2007\\n\\nAbstract: We propose a 4G system for transmission of video from a server at the base station to numerous wireless clients. We employ the latest technology in scalable video compression (3-D wavelet video coding) and in channel coding (punctured turbo codes); for the physical layer, we resort to the multicarrier chip-interleaved system with two-layer interleaving, which achieves high spectral efficiency and is very suitable for downlink applications. We develop fast algorithms for a cross-layer resource allocation that minimize the expected distortion of the reconstructed video averaged over all clients. The algorithms find a near-optimal power, bandwidth, and subcarrier allocation at the physical layer and a source-channel symbol allocation at the application layer. Our experimental results demonstrate that such a cross-layer optimization framework leads to higher quality performance of the overall system. Copyright (c) 2007 John Wiley & Sons, Ltd.\",\n \"Title: Compress-spread-forward with multiterminal source coding and complete complementary sequences\\nYear: 2009\\n\\nAbstract: We propose a new technique, compress-spread-forward (CSF), for high-performance wireless streaming from two base stations in parallel. CSF uses multiterminal source coding for efficient source compression and complete complementary sequences for error-free multiple access and synchronization. Our practical design shows significant performance gains due to spatial diversity and distributed source coding.\",\n \"Title: Multiresolution Watermarking for Images and Video: A Unified Approach\\nYear: 1998\\n\\nAbstract: This paper proposes a unified approach to digital watermarking of images and video based on the 2D and 3D discrete wavelet transforms. The hierarchical nature of the wavelet representation allows multiresolutional detection of the digital watermark, which is a Gaussian distributed random vector added to all the highpass bands in the wavelet domain. We show that, when subjected to distortion from compression or image halftoning, the corresponding watermark can still be correctly identified at each resolution (excluding the lowest one) in the wavelet domain. Computational saving from such a multiresolution watermarking framework is obvious, especially for the video care.\",\n \"Title: Optimal Resource Allocation for Wireless Video over CDMA Networks\\nYear: 2003\\n\\nAbstract: We present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. We map an embedded video bitstream, which is encoded into multiple independently decodable layers by 3D-ESCOT video coding technique, to multiple CDMA channels. One video source layer is transmitted over one CDMA channel. Each video source layer is protected by a product channel code structure. A product channel code is obtained by the combination of a row code based on rate-compatible punctured convolutional code (RCPC) with cyclic redundancy check (CRC) error detection and a source-channel column code, i.e., systematic rate-compatible Reed-Solomon (RS) style erasure code. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation, i.e., the optimal unequal Reed-Solomon code source/parity rate allocations and the optimal RCPC rate protection for each channel. In formulating such an optimization problem, we make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. The channel is modeled as the concatenation of wireless BER channel and a wireline packet erasure channel with a fixed packet loss probability. By solving the optimization problem, we obtain the optimal power level allocation and the optimal transmission rate allocation over multiple CDMA channels. For each CDMA channel, we also employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Simulation results show that the proposed framework allows the video quality to degrade gracefully as the fading worsens or the bandwidth decreases, and it offers improved video quality at the receiver.\",\n \"Title: Real-time unequal error protection algorithms for progressive image transmission\\nYear: 2003\\n\\nAbstract: We consider unequal error protection strategies for the efficient progressive transmission of embedded image codes over noisy channels. In progressive transmission, the reconstruction quality is important not only at the target transmission rate but also at the intermediate rates. An adequate error protection strategy may, thus, consist of optimizing the average performance over the set of intermediate rates. The performance can be the expected number of correctly decoded source bits or the expected distortion. For the rate-based performance, we prove some interesting properties of an optimal solution and give an optimal linear-time algorithm to compute it. For the distortion-based performance, we propose an efficient linear-time local search algorithm. For a binary symmetric channel, two state-of-the-art source coders (SPIHT and JPEG2000), we compare the progressive ability of our proposed solutions to that of the strategies that optimize the end-to-end performance of the system. Experimental results showed that the proposed solutions had a slightly worse performance at the target transmission rate and a better performance at most of the intermediate rates, especially at the lowest ones.\",\n \"Title: Packet loss protection of embedded data with fast local search\\nYear: 2002\\n\\nAbstract: Unequal loss protection with systematic Reed-Solomon codes al- lows reliable transmission of embedded multimedia over packet erasure channels. The design of a fast algorithm with low memory requirements for the computation of an unequal loss protection solution is essential in real-time systems. Because the determi- nation of an optimal solution is time-consuming, fast suboptimal solutions have been used. In this paper, we present a fast iterative improvement algorithm with negligible memory requirements. Ex- perimental results for the JPEG2000, 2D, and 3D set partitioning in hierarchical trees (SPIHT) coders showed that our algorithm provided close to optimal peak signal-to-noise ratio (PSNR) per- formance, while its time complexity was significantly lower than that of all previously proposed algorithms.\",\n \"Title: On code design for the Slepian-Wolf problem and lossless multiterminal networks\\nYear: 2006\\n\\nAbstract: A Slepian-Wolf coding scheme for compressing two uniform memoryless binary sources using a single channel code that can achieve arbitrary rate allocation among encoders was outlined in the work of Pradhan and Ramchandran. Inspired by this work, we address the problem of practical code design for general multiterminal lossless networks where multiple memoryless correlated binary sources are separately compressed and sent; each decoder receives a set of compressed sources and attempts to jointly reconstruct them. First, we propose a near-lossless practical code design for the Slepian-Wolf system with multiple sources. For two uniform sources, if the code approaches the capacity of the channel that models the correlation between the sources, then the system will approach the theoretical limit. Thus, the great advantage of this design method is its possibility to approach the theoretical limits with a single channel code for any rate allocation among the encoders. Based on Slepian-Wolf code constructions, we continue with providing practical designs for the general lossless multiterminal network which consists of an arbitrary number of encoders and decoders. Using irregular repeat-accumulate and turbo codes in our designs, we obtain the best results reported so far and almost reach the theoretical bounds.\",\n \"Title: 3D scene reconstruction by multiple structured-light based commodity depth cameras\\nYear: 2012\\n\\nAbstract: Commodity depth cameras have attracted a lot of research interest recently, in particular the structured-light based Kinect cameras available on the mass market. One important application of such cameras is 3D scene reconstruction and view synthesis. However, a single depth camera often has limited field of view and there is missing depth information when synthesizing a virtual view from a new viewpoint. In this paper, we study the problem of 3D scene reconstruction from multiple structured-light based depth cameras. Since multiple cameras may cause severe interference in the regions where the projected light overlaps, we present a novel planesweeping based algorithm to handle such interference. The proposed algorithm takes into account the correlation between multiple projectors and the infrared images as well as the correlation between the infrared images, thereby recovering the depth information for both overlapped and non-overlapped regions. Simulation results demonstrate that the proposed solution is very effective on various scenes.\",\n \"Title: Distributed Compression of Linear Functions: Partial Sum-Rate Tightness and Gap to Optimal Sum-Rate\\nYear: 2014\\n\\nAbstract: We consider the problem of distributed compression of the difference Z = Y1 - cY2 of two jointly Gaussian sources Y1 and Y2 under an MSE distortion constraint D on Z. The rate region for this problem is unknown if the correlation coefficient ρ and the weighting factor c satisfy cρ > 0. Inspired by Ahlswede and Han's scheme for the problem of distributed compression of the modulo-2 sum of two binary sources, we first propose a hybrid random-structured coding scheme that is capable of saving the sum-rate over both the random quantize-and-bin (QB) coding scheme and Krithivasan and Pradhan's structured lattice coding scheme. The main idea is to use a random coding component in the first layer to adjust the source correlation so that the structured coding component in the second layer can be more efficient with the outputs from the first layer as decoder side information. We then provide a new sum-rate lower bound for the problem in hand by connecting it to the Gaussian two-terminal source coding problem with covariance matrix distortion constraint. Our lower bound not only improves existing bounds in many cases, but also allows us to prove sum-rate tightness of the QB scheme when c is either relatively small or large and D is larger than some threshold. Furthermore, our lower bound enables us to show that our new hybrid scheme performs within two b/s from the optimal sum-rate for all values of ρ, c, and D.\",\n \"Title: Optimal rate allocation in progressive joint source-channel coding for image transmission over CDMA networks\\nYear: 2003\\n\\nAbstract: This paper presents an optimal rate allocation scheme in joint source-channel coding (JSCC) for image transmission over CDMA networks. Our scheme first uses progressive joint source-channel codes [V. Stankovic et al., Sep. 2002] to generate operational transmission rate-distortion (TR-D) functions of different multiple-access channels with different BERs. The Lagrange multiplier is then employed to set the optimal rate allocation among different channels, subject to a total transmission rate constraint. Progressive JSCC offers the scalability feature that is very attractive for handling bandwidth variations in wireless communications. By extending the rate-distortion function in source coding to the TR-D function in JSCC, our work borrows the \\\"equal slope\\\" argument [Y. Shoham and A. Gersho, Sep. 1988] to effectively solve the rate allocation problem in JSCC for multi-channel image transmission. Experiments show that our scheme runs in real time and provides competitive performance at all intermediate transmission rates.\",\n \"Title: Computing the channel capacity and rate-distortion function with two-sided state information\\nYear: 2005\\n\\nAbstract: In this correspondence, we present iterative algorithms that numerically compute the capacity-power and rate-distortion functions for coding with two-sided state information. Numerical examples are provided to demonstrate efficiency of our algorithms.\",\n \"Title: Distributed Source Coding for Multimedia Multicast Over Heterogeneous Networks\\nYear: 2007\\n\\nAbstract: Real-time multimedia multicast over wireless networks is an exciting application that has generated a lot of interest recently. Its main challenge lies in the stringent bandwidth and time-delay requirements of real-time multimedia and severe impairments of the wireless channels. We develop a network-aware cross-layer design for multimedia multicast over heterogeneous wireless-wireline networks, th...\",\n \"Title: Asymmetric code design for remote multiterminal source coding\\nYear: 2004\\n\\nAbstract: Asymmetric code design for remote multiterminal source coding in the quadratic Gaussian case is presented in this paper. For remote multiterminal source coding of X, to achieve the minimum sum rate of the two independent encoders subject to a fidelity criterion d, theoretical bounds were derived independently. The main idea is to quantize the first observation Y1 and apply Wyner-Ziv coding on Y2 by using the quantized version of Y1 as side information in an efficient asymmetric coding scheme. The practical code design gives results that are very close to the sum-rate bound.\",\n \"Title: Progressive coding of medical volumetric data using three-dimensional integer wavelet packet transform\\nYear: 1998\\n\\nAbstract: Examines progressive lossy-to-lossless compression of medical volumetric data using 3D integer wavelet packet transforms and set partitioning in hierarchical trees (SPIHT). To achieve good lossy coding performance, we describe a 3D integer wavelet packet transform that allows implicit bit shifting of wavelet coefficients to approximate a 3D unitary transformation. We also address context modeling for efficient entropy coding within the SPIHT framework. Both lossy and lossless coding performances are better than those reported by A. Bilgin et al. (1998)\",\n \"Title: Joint error control and power allocation for video transmission over CDMA networks with multiuser detection\\nYear: 2002\\n\\nAbstract: Error control and power allocation for transmitting wireless video over CDMA networks are considered in conjunction with multiuser detection. We map a layered video bitstream to several CDMA fading channels and inject multiple source/parity layers into each of these channels at the transmitter. At the receiver, we employ a linear minimum mean-square error (MMSE) multiuser detector in the uplink and two types of blind linear MMSE detectors in the downlink, for demodulating the received data. For given constraints on the available bandwidth and transmit power, the transmitter determines the optimal power allocation among different CDMA fading channels and the optimal number of source and parity packets to send that offer the best video quality. Simulation results show a performance gain of up to 1.5 dB with joint optimization over that with rate optimization only.\",\n \"Title: A DCT-based embedded image coder\\nYear: 1996\\n\\nAbstract: Since Shapiro (see ibid., vol.41, no.12, p. 445, 1993) published his work on embedded zerotree wavelet (EZW) image coding, there have been increased research activities in image coding centered around wavelets. We first point out that the wavelet transform is just one member in a family of linear transformations, and the discrete cosine transform (DCT) can also be coupled with an embedded zerotree quantizer. We then present such an image coder that outperforms any other DCT-based coder published in the literature, including that of the Joint Photographers Expert Group (JPEG). Moreover, our DCT-based embedded image coder gives higher peak signal-to-noise ratios (PSNR) than the quoted results of Shapiro's EZW coder.\",\n \"Title: Introduction to the Issue on MIMO-Optimized Transmission Systems for Delivering Data and Rich Content\\nYear: 2008\\n\\nAbstract: The 11 papers in this special issue focus on MIMO-optimized transmission systems for delivering data and rich content. The papers are summarized here.\",\n \"Title: Compress-forward coding with BPSK modulation for the half-duplex Gaussian relay channel\\nYear: 2009\\n\\nAbstract: This paper studies compress-forward (CF) coding with BPSK modulation for the half-duplex Gaussian relay channel. In CF relaying, Wyner-Ziv coding is applied at the relay to exploit the joint statistics between signals at the relay and the destination. We propose Slepian-Wolf coded nested scalar quantization (SWCNSQ) for practical Wyner-Ziv coding at the relay. We first provide the achievable rate of SWCNSQ based CF relaying as a performance benchmark, and then present a practical code design using low-density parity-check (LDPC) codes for error protection at the source, and nested scalar quantization plus irregular-repeat accumulation (IRA) codes for CF coding at the relay. The degree distributions of the LDPC and IRA codes are optimized using extrinsic information transfer charts and Gaussian approximation. Under discretized density evolution for asymptotically large block lengths, our optimized code design operates 0.11-0.21 dB away from the SWCNSQ limit for CF relaying. Simulations with LDPC/IRA codes of length 2 × 105 show a performance gap of 0.27-0.38 dB from the achievable rate.\",\n \"Title: Sending two Gaussians over the Gaussian MAC with bandwidth expansion\\nYear: 2012\\n\\nAbstract: The problem of sending two Gaussian sources over the Gaussian multiple access channel (MAC) with bandwidth expansion is studied. In this problem, two distributed transmitters desire to describe the two Gaussian sources to a common receiver subject to desired communication quality requirements and bandwidth expansion constraint. Of our interests is the minimum power and the transmission schemes to achieve power efficiency. Achievable bounds on the minimum power are given in this work.\",\n \"Title: Distributed Source And Joint Source-Channel Coding: From Theory To Practice\\nYear: 2005\\n\\nAbstract: This paper reviews the theory behind distributed source coding and distributed source-channel coding and surveys the progress made in code design during the last years.\",\n \"Title: Design of Slepian-Wolf Codes by Channel Code Partitioning\\nYear: 2004\\n\\nAbstract: A Slepian-Wolf coding scheme that can achieve arbitrary rate allocation amongtwo encoders was outlined in the work of Pradhan and Ramchandran. Inspired by thiswork, we start with a detailed solution for general (asymmetric or symmetric) Slepian-Wolfcoding based on partitioning a single systematic channel code, and continuewith practical code designs using advanced channel codes. By using systematic IRAand turbo codes, we devise a powerful scheme that is capable of approaching any pointon the Slepian-Wolf bound. We further study an extension of the technique to multiplesources, and show that for a particular correlation model among the sources, a singlepractical channel code can be designed for coding all the sources in symmetric andasymmetric scenarios. If the code approaches the capacity of the channel that modelsthe correlation between the sources, then the system will approach the Slepian-Wolflimit. Using systematic IRA and punctured turbo codes for coding two binary sources,each being independent identically distributed, with correlation modeled by a binarysymmetric channel, we obtain results which are 0.04 bits away from the theoreticallimit in both symmetric and asymmetric Slepian-Wolf settings.\",\n \"Title: Efficient rate allocation for progressive image transmission via unequal error protection over finite-state Markov channels\\nYear: 2005\\n\\nAbstract: This paper proposes a unified framework for addressing progressive image transmission over noisy channels based on the finite-state Markov channel (FSMC) model. FSMC models are simple yet general enough to model binary symmetric, Gilbert-Elliott, and fading channels. They allow error sequence analysis that facilitates quantifying the statistical characteristics of the embedded bitstreams transmitted over FSMC in closed form. Using a concatenation of rate-compatible puncturing convolutional code and cyclic redundancy check code for error protection, we use a concatenation of rate-compatible punctured convolutional code and cyclic redundancy check code for error protection, which results in an unequal error protection (UEP) system, and find (sub-)optimal rate allocation solutions for our setup. By mapping fading channels to FSMCs, the JSCC problem is thus solved without the burden of simulations using an image-dependent lookup table. Fast algorithms are proposed to search for the optimal UEP. Experiments on embedded image bitstreams over FSMCs confirm our analytical results.\",\n \"Title: Code design for MIMO broadcast channels\\nYear: 2009\\n\\nAbstract: Recent information-theoretic results show the optimality of dirty-paper coding (DPC) in achieving the full capacity region of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC). This paper presents a DPC based code design for BCs. We consider the case in which there is an individual rate/signal-to-interference-plus-noise ratio (SINR) constraint for each user. For a fixed transmitter power, we choose the linear transmit precoding matrix such that the SINRs at users are uniformly maximized, thus ensuring the best bit-error rate performance. We start with Cover's simplest two-user Gaussian BC and present a coding scheme that operates 1.44 dB from the boundary of the capacity region at the rate of one bit per real sample (b/s) for each user. We then extend the coding strategy to a two-user MIMO Gaussian BC with two transmit antennas at the base-station and develop the first limit-approaching code design using nested turbo codes for DPC. At the rate of 1 b/s for each user, our design operates 1.48 dB from the capacity region boundary. We also consider the performance of our scheme over a slow fading BC. For two transmit antennas, simulation results indicate a performance loss of only 1.4 dB, 1.64 dB and 1.99 dB from the theoretical limit in terms of the total transmission power for the two, three and four user case, respectively.\",\n \"Title: Layered Wyner-Ziv video coding for transmission over unreliable channels\\nYear: 2006\\n\\nAbstract: Based on recent works on Wyner-Ziv coding (WZC) (or lossy source coding with decoder side information), this paper considers the case with noisy channel and addresses distributed joint source-channel coding (JSCC), while targeting at the important application of scalable video transmission over wireless networks. In WZC, after quantization, Slepian-Wolf coding (SWC) is used to reduce the rate. SWC is traditionally realized by sending syndromes of a linear channel code. Since syndromes of the channel code can only compress but cannot protect, for transmission over noisy channels, additional error protection is needed. However, instead of using one channel code for SWC and one for error protection, our idea is to use a single channel code to achieve both compression and protection. We replace the traditional syndrome-based SWC scheme by the parity-based one, where only parity bits of the Slepian-Wolf channel code are sent. If the amount of transmitted parity bits increases above the Slepian-Wolf limit, the added redundancy is exploited to cope against the noise in the transmission channel. Using irregular repeat-accumulate codes for practical parity-based SWC, we design a novel layered Wyner-Ziv video coder which is robust to channel failures and thus very suitable for wireless communications. Our simulation results show great advantages of the proposed solution based on JSCC compared to the traditional approach where source and channel coding are performed separately.\",\n \"Title: On the sum-rate loss of quadratic Gaussian multiterminal source coding\\nYear: 2011\\n\\nAbstract: This work studies the sum-rate loss of quadratic Gaussian multiterminal source coding, i.e., the difference between the minimum sum-rates of distributed encoding and joint encoding (both with joint decoding) of correlated Gaussian sources subject to MSE distortion constraints on individual sources. It is shown that under the non-degraded assumption, i.e., all target distortions are simultaneously achievable by a Berger-Tung scheme, the supremum of the sum-rate loss of distributed encoding over joint encoding of L jointly Gaussian sources increases almost linearly in the number of sources L, with an asymptotic slope of 0.1083 b/s per source as L goes to infinity. This result is obtained even though we currently do not have the full knowledge of the minimum sum-rate for the distributed encoding case. The main idea is to upper-bound the minimum sum-rate of multiterminal source coding by that achieved by parallel Gaussian test channels while lower-bounding the minimum sum-rate of joint encoding by a reverse water-filling solution to a relaxed joint encoding problem of the same set of Gaussian sources with a sum-distortion constraint (that equals the sum of the individual target distortions). We show that under the non-degraded assumption, the supremum difference between the upper bound for distributed encoding and the lower bound for joint encoding is achieved in the bi-eigen equal-variance with equal distortion case, in which both bounds are known to be tight.\",\n \"Title: An improved lattice-based scheme for lossy distributed compression of linear functions\\nYear: 2011\\n\\nAbstract: It has recently been showed that lattice/structured codes can outperform random/unstructured codes in a number of scenarios of distributed source coding. One such instance involves lossy distributed compression of linear functions of Gaussian sources, which is the focus of this paper. Existing structured schemes employ “good” lattices for quantization and binning, however, the remaining correlation between the lattice coset indices are not exploited in an efficient way, leading to suboptimal performance when the target distortion is small. This paper proposes a new lattice-based scheme that is capable of eliminating the redundancy among coset indices and achieving a smaller sum-rate than existing schemes. The main novelty lies in the use of a hidden relationship between the coset planes of the quantization indices, and the enlarged set of choices for the quantizers as well as the linear estimation coefficients.\",\n \"Title: Block-based variable density compressed image sampling\\nYear: 2012\\n\\nAbstract: Compressed sampling (CS) is a technique that enables signal reconstruction at sub-Nyquist sampling rate. A key problem in CS is how to design the sampling scheme. In this paper, we propose a novel sampling method for compressed image sampling, which exploits a priori information and uses a block-based strategy to improve image reconstruction. Our block-based sampling scheme assigns more samples to blocks with more high-frequency contents while making sure that important coefficients of each block are sampled. Simulation results show that our proposed method outperforms existing methods on both reconstruction quality and running time.\",\n \"Title: Multiresolution watermarking for images and video\\nYear: 1999\\n\\nAbstract: This paper proposes a unified approach to digital watermarking of images and video based on the two- and three-dimensional discrete wavelet transforms. The hierarchical nature of the wavelet representation allows multiresolutional detection of the digital watermark, which is a Gaussian distributed random vector added to all the high-pass bands in the wavelet domain. We show that when subjected to distortion from compression or image halftoning, the corresponding watermark can still be correctly identified at each resolution (excluding the lowest one) in the wavelet domain. Computational savings from such a multiresolution watermarking framework is obvious, especially for the video case\",\n \"Title: A deblocking algorithm for JPEG compressed images using overcomplete wavelet representations\\nYear: 1997\\n\\nAbstract: This paper introduces a new approach to deblocking of JPEG compressed images using overcomplete wavelet representations. By exploiting cross-scale correlations among wavelet coefficients, edge information in the JPEG compressed images is extracted and protected, while blocky noise in the smooth background regions is smoothed out in the wavelet domain. Compared with the iterative methods reported in the literature, our simple wavelet-based method has much lower computational complexity, yet it is capable of achieving the same peak signal-to-noise ratio (PSNR) improvement as the best iterative method and giving visually very pleasing images as well\",\n \"Title: Recursive bilateral filter for encoder-integrated video denoising\\nYear: 2012\\n\\nAbstract: Video denoising based on temporal or spatiotemporal filtering is highly effective but computationally expensive due to the requirement of motion estimation. Encoder-integrated denoising is an efficient framework that embeds the filtering process into the encoding pipeline so that motion estimation for denoising can be avoided. State-of-the-arts encoder-integrated methods use Least Minimum Mean Square Error (LMMSE) optimal filters to reduce noise based on additive noise models. However, in practice, the LMMSE filters could result in blurred edges and visual artifacts due to inaccurate image signal estimation caused by outlier input samples and non-adaptivity within macroblocks. This paper presents new recursive bilateral filters that can be easily integrated into video encoders to tackle the limitations of the LMMSE filters. The robustness of the bilateral filters results in substantially better objective and subjective quality with marginal computation cost increase.\",\n \"Title: Scalable audio coding using the nonuniform modulated complex lapped transform\\nYear: 2001\\n\\nAbstract: This paper introduces a scalable audio coder using the nonuniform modulated complex lapped transform (NMCLT), which is a new nonuniform oversampled filter bank with a better combination of time- and frequency-domain localization than previous designs. Masking functions for different critical Bark bands are first calculated directly from the NMCLT coefficients as perceptual weights and arithmetic coding is then used to compress bit planes of the weighted NMCLT coefficients to generate a perceptually scalable audio bitstream. The loss in coding performance due to oversampling is offset by limiting the amount of redundancy in the transform and exploiting the correlations among the NMCLT basis functions. Experiments show that our new coder outperforms a coder with the modulated lapped transform (MLT) both objectively and subjectively.\",\n \"Title: Diversity analysis for space-time-frequency (STF) coded MIMO system with a general correlation model\\nYear: 2013\\n\\nAbstract: Previous works on space-time-frequency (STF) codes have focused on frequency-selective but independent fading channels for MIMO-OFDM systems. However, insufficient antenna space, mobile scenarios, and multipath in practice cause correlation in the spatial, temporal, and frequency domains. This paper studies the effect of STF coding on the performance of MIMO-OFDM systems with general spatial, temporal, and frequency/path correlated channels. Specifically, we first derive an upper bound on the maximum achievable diversity and then prove achievability by giving an STF code design example. Finally, we show that our general diversity result recovers those in the existing literature for special correlation structures.\",\n \"Title: On the minimum energy of sending Gaussian multiterminal sources over the Gaussian MAC\\nYear: 2013\\n\\nAbstract: We study the minimum energy of sending Gaussian multiterminal sources over the Gaussian multiple access channel (MAC). Distributed transmitters observe Gaussian multiterminal sources and describe their observations to a central decoder, which desires to reconstruct the sources under MSE constraints. We first lower bound the minimum energy by a cut-set argument which couples the transmitted signals and reconstruction errors. For achievability, separate source-channel coding is first studied as a benchmark. We then find out the minimum energy that can be achieved uncoded transmission. A hybrid digital/analog scheme is proposed to achieve the best known energy performance.\",\n \"Title: Subspace-based prototyping and classification of chromosome images.\\nYear: 2005\\n\\nAbstract: Chromosomes are essential genomic information carriers. Chromosome classification constitutes an important part of routine clinical and cancer cytogenetics analysis. Cytogeneticists perform visual interpretation of banded chromosome images according to the diagrammatic models of various chromosome types known as the ideograms, which mimic artists' depiction of the chromosomes. In this paper, we present a subspace-based approach for automated prototyping and classification of chromosome images. We show that 1) prototype chromosome images can be quantitatively synthesized from a subspace to objectively represent the chromosome images of a given type or population, and 2) the transformation coefficients (or projected coordinate values of sample chromosomes) in the subspace can be utilized as the extracted feature measurements for classification purposes. We examine in particular the formation of three well-known subspaces, namely the ones derived from principal component analysis (PCA), Fisher's linear discriminant analysis, and the discrete cosine transform (DCT). These subspaces are implemented and evaluated for prototyping two-dimensional (2-D) images and for classification of both 2-D images and one-dimensional profiles of chromosomes. Experimental results show that previously unseen prototype chromosome images of high visual quality can be synthesized using the proposed subspace-based method, and that PCA and the DCT significantly outperform the well-known benchmark technique of weighted density distribution functions in classifying 2-D chromosome images.\",\n \"Title: Determination of the optimal number of features for quadratic discriminant analysis via the normal approximation to the discriminant distribution\\nYear: 2005\\n\\nAbstract: Given the joint feature-label distribution, increasing the number of features always results in decreased classification error; however, this is not the case when a classifier is designed via a classification rule from sample data. Typically, for fixed sample size, the error of a designed classifier decreases and then increases as the number of features grows. The problem is especially acute when sample sizes are very small and the potential number of features is very large. To obtain a general understanding of the kinds of feature-set sizes that provide good performance for a particular classification rule, performance must be evaluated based on accurate error estimation, and hence a model-based setting for optimizing the number of features is needed. This paper treats quadratic discriminant analysis (QDA) in the case of unequal covariance matrices. For two normal class-conditional distributions, the QDA classifier is determined according to a discriminant. The standard plug-in rule estimates the discriminant from a feature-label sample to obtain an estimate of the discriminant by replacing the means and covariance matrices by their respective sample means and sample covariance matrices. The unbiasedness of these estimators assures good estimation for large samples, but not for small samples. Our goal is to find an essentially analytic method to produce an error curve as a function of the number of features so that the curve can be minimized to determine an optimal number of features. We use a normal approximation to the distribution of the estimated discriminant. Since the mean and variance of the estimated discriminant will be exact, these provide insight into how the covariance matrices affect the optimal number of features. We derive the mean and variance of the estimated discriminant and compare feature-size optimization using the normal approximation to the estimated discriminant with optimization obtained by simulating the true distribution of the estimated discriminant. Optimization via the normal approximation to the estimated discriminant provides huge computational savings in comparison to optimization via simulation of the true distribution. Feature-size optimization via the normal approximation is very accurate when the covariance matrices differ modestly. The optimal number of features based on the normal approximation will exceed the actual optimal number when there is large disagreement between the covariance matrices; however, this difference is not important because the true misclassification error using the number of features obtained from the normal approximation and the number obtained from the true distribution differ only slightly, even for significantly different covariance matrices.\",\n \"Title: An optimal packetization scheme for fine granularity scalable bitstream\\nYear: 2002\\n\\nAbstract: This paper addresses the problem of optimal packetization for a fine granularity scalable (FGS) bitstream. A very general performance metric for streaming FGS bitstreams over packet erasure networks is first defined and analyzed. Then three packetization strategies, namely baseline packetization, binary-tree packetization and optimal packetization are presented, justified and compared. Finally, some experimental results are presented to demonstrate the effectiveness of the packetization schemes.\",\n \"Title: Scalable image transmission using rate-compatible irregular repeat accumulate (IRA) codes\\nYear: 2002\\n\\nAbstract: This paper considers designing and applying rate-compatible irregular repeat accumulate (IRA) codes for scalable image transmission over binary symmetric channels. IRA codes of different rates are obtained by puncturing the parity bits of a mother IRA code which uses a systematic encoder. One of the main ideas presented here is the design of the mother code such that the entire set of higher rate codes obtained by puncturing are good. Using the Viterbi algorithm for finding the optimal unequal error protection of JPEG2000 bit streams, we present better results with IRA codes than those reported with turbo codes. The proposed IRA codes also have lower decoding complexity than the turbo codes.\",\n \"Title: Code design for quadratic Gaussian multiterminal source coding: the symmetric case\\nYear: 2009\\n\\nAbstract: Whereas the theory and practice of two-terminal quadratic Gaussian multiterminal (MT) source coding is complete, the theory with more than two terminals is only partial, with the sum-rate limit only known in the symmetric case where all sources are positively symmetric and all target distortions equal. This paper proposes the first code design for quadratic Gaussian MT source coding in this symmetric setup. The aim is to approach corner points of the rate region via TCQ for quantization and LDPC codes for Slepian-Wolf compression. We provide high-rate analysis of our code design. Simulations with three and four terminals show a very small sum-rate loss.\",\n \"Title: Optimal rate allocation for progressive fine granularity scalable video coding\\nYear: 2001\\n\\nAbstract: We examine the enhancement-layer rate allocation problem in progressive fine granularity scalable (PFGS) video coding. The problem arises from the fact that different frames in the enhancement layer have different rates in PFGS coding. A rate-distortion (R-D) function for a multiframe group is first established for enhancement-layer PFGS coding, followed by experiments to verify its validity using real test sequences. Optimal rate allocation among frames in the group is then given based on the R-D function, together with a simple implementation that is suitable for applications such as streaming video. Experiments show that, compared with uniform bit allocation, optimal bit allocation not only makes the quality variation in decoded video much smoother, but also improves the average PSNR of PFGS coding by 0.3-0.5 dB.\",\n \"Title: Efficient channel code rate selection algorithms for forward error correction of packetized multimedia bitstreams in varying channels\\nYear: 2004\\n\\nAbstract: We study joint source-channel coding systems for the transmission of images over varying channels without feedback. We consider the situation where the channel statistics are unknown to the transmitter and focus on systems that enable good performance over a wide range of channel conditions. We first propose a linear-time channel code rate selection algorithm for a hybrid transmission system that combines packetization of an embedded wavelet bitstream into independently decodable packets and forward error correction with a concatenated cyclic redundancy check/rate-compatible punctured convolutional (RCPC) channel coder. We then consider an extension of this hybrid system with additional Reed-Solomon (RS) coding across the packets and give a linear-time algorithm for the efficient selection of both the RS and RCPC code rates. Experimental results for a wireline/wireless link modeled as the combination of a packet erasure channel and a Rayleigh flat-fading channel showed that our schemes significantly outperformed the best previous forward error correction systems in many situations where the actual channel parameter values deviated from the ones used in the optimization of the source-channel rate allocation.\",\n \"Title: Real-time error protection of embedded codes for packet erasure and fading channels\\nYear: 2004\\n\\nAbstract: Reliable real-time transmission of packetized embedded multimedia data over noisy channels requires the design of fast error control algorithms. For packet erasure channels, efficient forward error correction is obtained by using systematic Reed-Solomon (RS) codes across packets. For fading channels, state-of-the-art performance is given by a product channel code where each column code is an RS code and each row code is a concatenation of an outer cyclic redundancy check code and an inner rate-compatible punctured convolutional code. For each of these two systems, we propose a low-memory linear-time iterative improvement algorithm to compute an error protection solution. Experimental results for the two-dimensional and three-dimensional set partitioning in hierarchical trees coders showed that our algorithms provide close to optimal average peak signal-to-noise ratio performance, and that their running time is significantly lower than that of all previously proposed solutions.\",\n \"Title: Face Hallucination Via Weighted Sparse Representation\\nYear: 2013\\n\\nAbstract: By incorporating the priors of image positions, position-patch based face hallucination methods can produce high-quality results and save computation time. These methods represent the test image patch as a linear combination of the same position patches in a training dictionary, and the key issue is how to obtain the optimal coefficients. Due to stability and accuracy issues, methods based on least square estimation or sparse representation (SR) proposed so far are not satisfactory. In this paper, we improve existing SR methods by exploiting similarity between the test and training patches. In particular, we impose a similarity constraint (in terms of the distance between the test patch and bases in the dictionary) on the l(1) minimization regularization term and obtain the coefficients by solving a weighted SR problem. We also provide a new prospective on weighted SR and investigate its robustness to illumination variations. Experiments on commonly used database demonstrate that our method outperforms state of the art.\",\n \"Title: Fast Forward Error Protection Of Packetized Multimedia Bitstreams For Transmission Over Varying Channels\\nYear: 2003\\n\\nAbstract: We propose a real-time optimization algorithm that selects an appropriate channel code for hybrid systems that combine packetization of an embedded wavelet bitstream into independently decodable packets and forward error correction using a family of channel codes with error detection and error correction capability. Such systems are very powerful for the transmission of audio, images, and video over fading and erasure channels with varying statistics. We also give an implementation that uses an optimal packetization technique and a concatenated cyclic redundancy check/rate-compatible punctured convolutional coder. Experimental results show that the peak signal-to-noise ratio of the average mean square error of our system is up to 1.74 dB higher than that of the previous best hybrid system for a Rayleigh fading channel and a transmission rate of 0.25 bits per pixel. Finally, we compare the hybrid approach to a state-of-the-art approach that uses a product code to protect the information bitstream.\",\n \"Title: Advanced motion threading for 3D wavelet video coding\\nYear: 2004\\n\\nAbstract: This paper presents an advanced motion threading technique for improved performance in 3D wavelet coding. First, we extend an original motion threading idea of ours to a lifting- based implementation. Methods for enabling fractional-pixel alignment in motion threading and for processing many-to-one pixel mapping and non-referred pixels are proposed to reduce the wavelet boundary effects. Second, we devise an advanced motion threading technique, in which one set of motion vectors is generated for each temporal layer of wavelet coefficients for temporal scalability. In order to reduce the motion overhead information, especially at low bit rates, several correlated motion prediction modes at the macroblock level are defined to exploit the intra/inter layer correlation in motion vector coding. Finally, rate-distortion optimization is utilized in motion estimation to select the best motion prediction mode for each macroblock. With the new motion threading technique, we are able to achieve 1.5–6.0dB gain in average PSNR in 3D wavelet coding over our previous implementation of motion threading.\",\n \"Title: Noise-injected neural networks show promise for use on small-sample expression data.\\nYear: 2006\\n\\nAbstract: Overfitting the data is a salient issue for classifier design in small-sample settings. This is why selecting a classifier from a constrained family of classifiers, ones that do not possess the potential to too finely partition the feature space, is typically preferable. But overfitting is not merely a consequence of the classifier family; it is highly dependent on the classification rule used to design a classifier from the sample data. Thus, it is possible to consider families that are rather complex but for which there are classification rules that perform well for small samples. Such classification rules can be advantageous because they facilitate satisfactory classification when the class-conditional distributions are not easily separated and the sample is not large. Here we consider neural networks, from the perspectives of classical design based solely on the sample data and from noise-injection-based design.This paper provides an extensive simulation-based comparative study of noise-injected neural-network design. It considers a number of different feature-label models across various small sample sizes using varying amounts of noise injection. Besides comparing noise-injected neural-network design to classical neural-network design, the paper compares it to a number of other classification rules. Our particular interest is with the use of microarray data for expression-based classification for diagnosis and prognosis. To that end, we consider noise-injected neural-network design as it relates to a study of survivability of breast cancer patients.The conclusion is that in many instances noise-injected neural network design is superior to the other tested methods, and in almost all cases it does not perform substantially worse than the best of the other methods. Since the amount of noise injected is consequential, the effect of differing amounts of injected noise must be considered.\",\n \"Title: On optimal subspaces for appearance-based object recognition\\nYear: 2002\\n\\nAbstract: On the subject of optimal subspaces for appearance-based object recognition, it is generally believed that algorithms based on LDA (Linear Discriminant Analysis) are superior to those based on PCA (Principal Components Analysis), provided that relatively large training data sets are available (3, 5). In this paper, We show that while this is generally true for classification with the nearest-neighbor classifier, it is not always the case with a maximum-likelihood classifier. We support our claim by presenting both intuitively plausi- ble arguments and actual results on a large data set of human chromosomes. Our conjecture is that perhaps only when the underlying object classes are linearly separable would LDA be truly superior to other known subspaces of equal dimen- sionality.\",\n \"Title: Progressive image transmission over differentially space-time coded OFDM systems\\nYear: 2006\\n\\nAbstract: In this paper, we consider progressive image transmission over differentially space-time coded orthogonal frequency-division multiplexing (OFDM) systems and treat the problem as one of optimal joint source-channel coding (JSCC) in the form of unequal error protection (UEP), as necessitated by embedded source coding (e.g., SPIHT and JPEG 2000). We adopt a product channel code structure that is proven to provide powerful error protection and employ low-complexity decision-feedback decoding for differentially space-time coded OFDM without assuming channel state information. For a given SNR, the BER performance of the differentially spacetime coded OFDM system is treated as the channel condition in the JSCC/UEP design via a fast product code optimization algorithm so that the end-to-end quality of reconstructed images is optimized in the average minimum MSE sense. Extensive image transmission experiments show that SNR/BER improvements can be translated into quality gains in reconstructed images. Moreover, compared to another non-coherent detection algorithm, i.e., the iterative receiver based on expectation-maximization algorithm for the space-time coded OFDM systems, differentially space-time coded OFDM systems suffer some quality loss in reconstructed images. With the efficiency and simplicity of decision-feedback differential decoding, differentially space-time coded OFDM is thus a feasible modulation scheme for applications such as wireless image over mobile devices (e.g., cell phones). Copyright (C) 2006 John Wiley & Sons, Ltd.\",\n \"Title: PAGER: a distributed algorithm for the dead-end problem of location-based routing in sensor networks\\nYear: 2004\\n\\nAbstract: The dead-end problem is an importance issue of location-based routing in sensor networks, which occurs when a message falls into a local minimum using greedy forwarding. Current methods for this problem are insufficient either in eliminating traffic/path memorization or finding satisfied short paths. In this paper, we propose a novel algorithm, named partial-partition avoiding geographic routing (PAGER), to solve the problem. The basic idea of PAGER is to divide a sensor network graph into functional sub-graphs, and provide each sensor node with message forwarding directions based on these sub-graphs. That results in loop-free short paths without memorization of traffics/paths in sensor nodes. We implement our algorithm in a protocol and evaluate it in sensor networks with different parameters. Results show that PAGER generates considerably shorter paths, higher delivery ratio and lower energy consumption than the greedy perimeter stateless routing protocol. At the same time, PAGER achieves better performance in handling large-scale networks than the ad-hoc on-demand distance vector protocol\",\n \"Title: The sum-rate bound for a new class of quadratic Gaussian multiterminal source coding problems\\nYear: 2012\\n\\nAbstract: In this paper we show tightness of the Berger-Tung (BT) sum-rate bound for a new class of quadratic Gaussian multiterminal (MT) source coding problems dubbed bi-eigen equal-variance with equal distortion (BEEV-ED), where the L à L source covariance matrix has equal diagonal elements with two distinct eigenvalues, and the L target distortions are equal. Let K(K < L) be the number of larger eigenvalues, the BEEV covariance structure allows us to connect K i.i.d virtual Gaussian sources with the L given MT sources via an L à K semiorthogonal transform whose rows have equal Euclidean norm plus additive i.i.d. Gaussian noises, resulting in the two sets of sources being mutually conditional i.i.d. By relating the given MT source coding problem to a generalized Gaussian CEO problem with the K virtual sources as remote sources and the L MT sources as observations, we obtain a lower bound on the MT sum-rate, and show its achievability by BT schemes under the equal distortion constraints. Our BEEV-ED class of quadratic Gaussian MT source coding problems subsumes both the positive-symmetric case considered by Wagner et al. and the negative-symmetric case. Other examples, including a subclass of sources with BE circulant symmetric covariance matrices and equal distortion constraints, are also provided to highlight tightness of the sum-rate bound.\",\n \"Title: Scalable image and video transmission using irregular repeat-accumulate codes with fast algorithm for optimal unequal error protection\\nYear: 2004\\n\\nAbstract: This paper considers designing and applying punctured irregular repeat-accumulate (IRA) codes for scalable image and video transmission over binary symmetric channels. IRA codes of different rates are obtained by puncturing the parity bits of a mother IRA code, which uses a systematic encoder. One of the main ideas presented here is the design of the mother code such that the entire set of higher rate codes obtained by puncturing are good. To find a good unequal error protection for embedded bit streams, we employ the fast joint source-channel coding algorithm in Hamzaoui et al. to minimize the expected end-to-end distortion. We test with two scalable image coders (SPIHT and JPEG-2000) and two scalable video coders (3-D SPIHT and H.26L-based PFGS). Simulations show better results with IRA codes than those reported in Banister et al. with JPEG-2000 and turbo codes. The IRA codes proposed here also have lower decoding complexity than the turbo codes used by Banister et al.\",\n \"Title: Source-Channel Coding For Algebraic Multiterminal Binning\\nYear: 2004\\n\\nAbstract: This paper addresses practical code design problems for multiterminal communication networks. The basic element of a multiterminal network code is the binning scheme. We aim to develop a unified practical code design paradigm for related problems in multiterminal networks based on source-channel coding for algebraic binning. First, a framework based on Slepian-Woff coded quantization is highlighted for Wyner-Ziv coding and multiterminal source coding (e.g., the CEO problem). Then, a nested turbo scheme is proposed for Costa coding by exploiting the duality between Costa coding and Wyner-Ziv coding.\",\n \"Title: Image enhancement using multiscale oriented wavelets\\nYear: 2001\\n\\nAbstract: We describe a novel method of enhancing image geometric features using the oriented wavelets introduced in our earlier work (see Yu-Ping Wang, IEEE Trans. Image Proc., vol.8, no.12, p.1757-71, 1999). The poor directional selectivity of the conventional 2D wavelet transform has been circumvented by using this class of oriented wavelets. By taking advantage of directional wavelet decomposition, both the directional and scale correlation information are utilized for enhancing salient structures in images. To remove phase dependence, a pair of quadrature filters are used. The proposed algorithm has been applied to chromosome image enhancement. Comparisons of this algorithm with other approaches are presented\",\n \"Title: Image enhancement using multiscale differential operators\\nYear: 2001\\n\\nAbstract: Differential operators have been widely used for multiscale geometric descriptions of images. Efficient computation of these differential operators can be obtained by taking advantage of the spline techniques. We make use of a special class of these operators for image enhancement, with a particular application to chromosome image enhancement. These operators constitute a translation invariant wavelet transform well suited for the structural description of chromosome geometry. Based on the fact that the geometrical features like edges are correlated between different scales in the representation, a novel algorithm is designed to enhance the salient features of the image. Comparisons of this algorithm with other approaches are presented.\",\n \"Title: Cooperation in the MAC channel using frequency division multiplexing\\nYear: 2009\\n\\nAbstract: This paper considers cooperation in the low power/SNR regime for the multiple access channel. We assume that transmitters have no channel state information, and consider the outage capacity. We further assume that the nodes operate in half duplex. The nodes are multiplexed by assigning to each node a unique frequency band via frequency division multiplexing (FDM). A node transmits only on this band while listening on the others. We perform outage wideband analysis on FDM based cooperation, and show perhaps surprisingly that FDM loses very little in performance compared to the idealized situation where nodes can operate in full duplex. We then develop practical rateless coding methods for FDM using Raptor codes.\",\n \"Title: On optimal packetization of embedded bitstreams\\nYear: 2000\\n\\nAbstract: We investigate the problem of packetizing multiple embedded bitstreams to improve the error resilience of source codes. We discuss various packetization schemes against packet erasure at both low and high bit rates. We formulate various versions of packetization of multiple embedded bitstreams for minimum distortion as discrete optimization problems, and propose efficient algorithms to compute globally optimal solutions to these problems\",\n \"Title: Joint UEP and layered source coding with application to transmission of JPEG-2000 coded images\\nYear: 2001\\n\\nAbstract: This paper presents a joint source-channel coding framework based on layered source coding and Reed-Solomon channel coding for unequal error protection. An iterative procedure is described to search for the best source coding rate and the optimal UEP of layered bitstreams. We apply our JSCC technique to transmission of JPEG-2000 coded images over binary symmetric channels. Compared to results reported in the literature, our UEP based approach gives better results while having lower complexity\",\n \"Title: A Robust Multi-Level Design for Dirty-Paper Coding.\\nYear: 2013\\n\\nAbstract: We propose a robust close-to-capacity dirty-paper coding (DPC) design framework in which multi-level low density parity check (LDPC) codes and trellis coded quantization (TCQ) are employed as the channel and source coding components, respectively. The proposed design framework is robust in the sense that it yields close to capacity solutions in the high-, medium-, and low-rate regimes. This is in contrast to existing practical DPC schemes that perform well only in one or two of these regimes, but not all three. We design codes for transmission rates of 0.5, 1.0, 1.5, and 2.0 bits/sample (b/s) using one, two, three, and four LDPC levels; at a block length of 210 5 , the codes perform 0.95, 0.58, 0.55, and 0.54 dB from the corresponding information theoretic limits, respectively. We also propose a low-complexity decoding scheme that does not involve iterative message passing between the source and channel decoders; the low-complexity scheme performs only 1.08, 0.85, and 0.79 dB away from the theoretical limits at transmission rates of 1.0, 1.5, and 2.0 b/s, respectively.\",\n \"Title: On Multiterminal Source Code Design\\nYear: 2008\\n\\nAbstract: Multiterminal (MT) source coding refers to separate lossy encoding and joint decoding of multiple correlated sources. Recently, the rate region of both direct and indirect MT source coding in the quadratic Gaussian setup with two encoders was determined. We are thus motivated to design practical MT source codes that can potentially achieve the entire rate region. In this paper, we present two practical MT coding schemes under the framework of Slepian-Wolf coded quantization (SWCQ) for both direct and indirect MT problems. The first, asymmetric SWCQ scheme relies on quantization and Wyner-Ziv coding, and it is implemented via source splitting to achieve any point on the sum-rate bound. In the second, conceptually simpler scheme, symmetric SWCQ, the two quantized sources are compressed using symmetric Slepian-Wolf coding via a channel code partitioning technique that is capable of achieving any point on the Slepian-Wolf sum-rate bound. Our practical designs employ trellis-coded quantization and turbo/low-density parity-check (LDPC) codes for both asymmetric and symmetric Slepian-Wolf coding. Simulation results show a gap of only 0.139-0.194 bit per sample away from the sum-rate bound for both direct and indirect MT coding problems.\",\n \"Title: Depth camera assisted multiterminal video coding\\nYear: 2011\\n\\nAbstract: This paper addresses multiterminal video coding with the help of a low-resolution depth camera. In this setup, the depth sequence, together with the high-resolution texture sequences, are collected, compressed and transmitted separately to the joint decoder in order to obtain more accurate depth information and consequently better rate-distortion performance. At the decoder end, side information (for Wyner-Ziv coding) is generated based on successive refinement of the decompressed low-resolution depth map and texture frame warped from other terminals. Experimental results show sum-rate savings with the depth camera than without for the same PSNR performance. Comparisons to simulcast and JMVM coding are also provided. Although the sum-rate gain of our multiterminal video coding scheme (with or without the depth camera) over simulcast is relatively small, this work is the first that incorporates depth camera in a multiterminal setting.\",\n \"Title: Fast algorithm for distortion-based error protection of embedded image codes.\\nYear: 2005\\n\\nAbstract: We consider a joint source-channel coding system that protects an embedded bitstream using a finite family of channel codes with error detection and error correction capability. The performance of this system may be measured by the expected distortion or by the expected number of correctly decoded source bits. Whereas a rate-based optimal solution can be found in linear time, the computation of a distortion-based optimal solution is prohibitive. Under the assumption of the convexity of the operational distortion-rate function of the source coder, we give a lower bound on the expected distortion of a distortion-based optimal solution that depends only on a rate-based optimal solution. Then, we propose a local search (LS) algorithm that starts from a rate-based optimal solution and converges in linear time to a local minimum of the expected distortion. Experimental results for a binary symmetric channel show that our LS algorithm is near optimal, whereas its complexity is much lower than that of the previous best solution.\",\n \"Title: Packet Erasure Protection for Multicasting\\nYear: 2004\\n\\nAbstract: Priority encoding transmission is an efficient forward error correction system for the robust transmission of scalable image and video data over packeterasure networks. For a memoryless packet erasure channel we first study thesensitivity of an optimal protection solution to a change in the packet erasurerate and in the number of packets. We then propose a practical error protectionalgorithm for multicasting and broadcasting applications. Instead of computing an optimal solution for each client independently, we show that comparableresults can be obtained much faster by refining protections already computedfor other clients. We also consider the situation where clients share a bottleneck link and develop layered multiple description codes that provide a betterquality trade-off among all clients than previous solutions.\",\n \"Title: An automatic and robust algorithm of reestablishment of digital dental occlusion.\\nYear: 2010\\n\\nAbstract: In the field of craniomaxillofacial (CMF) surgery, surgical planning can be performed on composite 3-D models that are generated by merging a computerized tomography scan with digital dental models. Digital dental models can be generated by scanning the surfaces of plaster dental models or dental impressions with a high-resolution laser scanner. During the planning process, one of the essential steps is to reestablish the dental occlusion. Unfortunately, this task is time-consuming and often inaccurate. This paper presents a new approach to automatically and efficiently reestablish dental occlusion. It includes two steps. The first step is to initially position the models based on dental curves and a point matching technique. The second step is to reposition the models to the final desired occlusion based on iterative surface-based minimum distance mapping with collision constraints. With linearization of rotation matrix, the alignment is modeled by solving quadratic programming. The simulation was completed on 12 sets of digital dental models. Two sets of dental models were partially edentulous, and another two sets have first premolar extractions for orthodontic treatment. Two validation methods were applied to the articulated models. The results show that using our method, the dental models can be successfully articulated with a small degree of deviations from the occlusion achieved with the gold-standard method.\",\n \"Title: Wavelet packets-based image coding using joint space-frequency quantization\\nYear: 1994\\n\\nAbstract: A novel quantization scheme targeted at jointly optimizing the spatial and frequency characterization of the wavelet representation of images was introduced in Xiong et al. (1993) for image compression applications. The present authors extend the concept of joint space-frequency quantization (SFQ) to the more flexible class of wavelet packet representations (Coifman and Wickerhauser, 1992), which are a generalization of the multiresolution decomposition using the wavelet transform. They propose a fast algorithm to jointly search for the best wavelet packet basis and space-frequency quantizer, presenting empirical evidence of its high performance (e.g., for the “Barbara” image coded at 0.5 b/p, they get a 0.7 dB gain in PSNR over the fixed-wavelet based SFQ of Xiong et al. and 1.5 dB over Shapiro's embedded wavelet coder (Shapiro, 1993))\",\n \"Title: Optimized error protection of scalable image bit streams [advances in joint source-channel coding for images\\nYear: 2005\\n\\nAbstract: This article focuses on FEC for scalable image coders. For various channel models, we survey recent progress made in system design and discuss efficient source-channel bit allocation techniques, with emphasis on unequal error protection. This article considered JSCC (joint source-channel coding) at the application layer only. Recent research has studied cross-layer optimization where JSCC is appli...\",\n \"Title: Layered Wyner-Ziv video coding.\\nYear: 2006\\n\\nAbstract: Following recent theoretical works on successive Wyner-Ziv coding (WZC), we propose a practical layered Wyner-Ziv video coder using the DCT, nested scalar quantization, and irregular LDPC code based Slepian-Wolf coding (or lossless source coding with side information at the decoder). Our main novelty is to use the base layer of a standard scalable video coder (e.g., MPEG-4/H.26L FGS or H.263+) as the decoder side information and perform layered WZC for quality enhancement. Similar to FGS coding, there is no performance difference between layered and monolithic WZC when the enhancement bitstream is generated in our proposed coder. Using an H.26L coded version as the base layer, experiments indicate that WZC gives slightly worse performance than FGS coding when the channel (for both the base and enhancement layers) is noiseless. However, when the channel is noisy, extensive simulations of video transmission over wireless networks conforming to the CDMA2000 1X standard show that H.26L base layer coding plus Wyner-Ziv enhancement layer coding are more robust against channel errors than H.26L FGS coding. These results demonstrate that layered Wyner-Ziv video coding is a promising new technique for video streaming over wireless networks.\",\n \"Title: On the Generalized Gaussian CEO Problem.\\nYear: 2012\\n\\nAbstract: This paper considers a distributed source coding (DSC) problem where L encoders observe noisy linear combinations of K correlated remote Gaussian sources, and separately transmit the compressed observations to the decoder to reconstruct the remote sources subject to a sum-distortion constraint. This DSC problem is referred to as the generalized Gaussian CEO problem since it can be viewed as a generalization of the quadratic Gaussian CEO problem where the number of remote source K=1. First, we provide a new outer region obtained using the entropy power inequality and an equivalent argument (in the sense of having the same rate-distortion region and Berger-Tung inner region) among a certain class of generalized Gaussian CEO problems. We then give two sufficient conditions for our new outer region to match the inner region achieved by Berger-Tung schemes, where the second matching condition implies that in the low-distortion regime, the Berger-Tung inner rate region is always tight, while in the high-distortion regime, the same region is tight if a certain condition holds. The sum-rate part of the outer region is also studied and shown to meet the Berger-Tung sum-rate upper bound under a certain condition, which is obtained using the Karush-Kuhn-Tucker conditions of the underlying convex semidefinite optimization problem, and is in general weaker than the aforesaid two for rate region tightness.\",\n \"Title: Optimal number of features as a function of sample size for various classification rules.\\nYear: 2005\\n\\nAbstract: Given the joint feature-label distribution, increasing the number of features always results in decreased classification error; however, this is not the case when a classifier is designed via a classification rule from sample data. Typically (but not always), for fixed sample size, the error of a designed classifier decreases and then increases as the number of features grows. The potential downside of using too many features is most critical for small samples, which are commonplace for gene-expression-based classifiers for phenotype discrimination. For fixed sample size and feature-label distribution, the issue is to find an optimal number of features.Since only in rare cases is there a known distribution of the error as a function of the number of features and sample size, this study employs simulation for various feature-label distributions and classification rules, and across a wide range of sample and feature-set sizes. To achieve the desired end, finding the optimal number of features as a function of sample size, it employs massively parallel computation. Seven classifiers are treated: 3-nearest-neighbor, Gaussian kernel, linear support vector machine, polynomial support vector machine, perceptron, regular histogram and linear discriminant analysis. Three Gaussian-based models are considered: linear, nonlinear and bimodal. In addition, real patient data from a large breast-cancer study is considered. To mitigate the combinatorial search for finding optimal feature sets, and to model the situation in which subsets of genes are co-regulated and correlation is internal to these subsets, we assume that the covariance matrix of the features is blocked, with each block corresponding to a group of correlated features. Altogether there are a large number of error surfaces for the many cases. These are provided in full on a companion website, which is meant to serve as resource for those working with small-sample classification.For the companion website, please visit http://public.tgen.org/tamu/ofs/e-dougherty@ee.tamu.edu.\",\n \"Title: Feasibility of interference neutralization in relay-aided MIMO interference broadcast channel with partial connectivity\\nYear: 2013\\n\\nAbstract: In this paper, we study the feasibility of interference neutralization (IN) in partially connected relay-aided multi-input-multi-output (MIMO) interference broadcast channel (IBC), where each relay only communicates with users in the same cell. Due to partial connectivity, there is no need to exchange channel information among the relays in different cells. We first present the necessary and sufficient condition for IN feasibility using linear transceiver. We then provide the minimum relay configuration required to support the maximal number of data streams without interference. Finally, the achievable degrees-of-freedomregion is obtained.\",\n \"Title: Normalization benefits microarray-based classification.\\nYear: 2006\\n\\nAbstract: When using cDNA microarrays, normalization to correct labeling bias is a common preliminary step before further data analysis is applied, its objective being to reduce the variation between arrays. To date, assessment of the effectiveness of normalization has mainly been confined to the ability to detect differentially expressed genes. Since a major use of microarrays is the expression-based phenotype classification, it is important to evaluate microarray normalization procedures relative to classification. Using a model-based approach, we model the systemic-error process to generate synthetic gene-expression values with known ground truth. These synthetic expression values are subjected to typical normalization methods and passed through a set of classification rules, the objective being to carry out a systematic study of the effect of normalization on classification. Three normalization methods are considered: offset, linear regression, and Lowess regression. Seven classification rules are considered: 3-nearest neighbor, linear support vector machine, linear discriminant analysis, regular histogram, Gaussian kernel, perceptron, and multiple perceptron with majority voting. The results of the first three are presented in the paper, with the full results being given on a complementary website. The conclusion from the different experiment models considered in the study is that normalization can have a significant benefit for classification under difficult experimental conditions, with linear and Lowess regression slightly outperforming the offset method.\",\n \"Title: Wyner-Ziv coding based on TCQ and LDPC codes\\nYear: 2009\\n\\nAbstract: This paper considers trellis coded quantization (TCQ) and low-density parity-check (LDPC) codes for the quadratic Gaussian Wyner-Ziv coding problem. After TCQ of the source X, LDPC codes are used to implement Slepian-Wolf coding of the quantized source Q(X) with side information Y at the decoder. Assuming 256-state TCQ and ideal Slepian-Wolf coding in the sense of achieving the theoretical limit H(Q(X)|Y), we experimentally show that Slepian-Wolf coded TCQ performs 0.2 dB away from the Wyner-Ziv distortion-rate function DWZ(R) at high rate. This result mirrors that of entropy-constrained TCQ in classic source coding of Gaussian sources. Furthermore, using 8,192-state TCQ and assuming ideal Slepian-Wolf coding, our simulations show that Slepian-Wolf coded TCQ performs only 0.1 dB away from DWZ(R) at high rate. These results establish the practical performance limit of Slepian-Wolf coded TCQ for quadratic Gaussian Wyner-Ziv coding. Practical designs give performance very close to the theoretical limit. For example, with 8,192-state TCQ, irregular LDPC codes for Slepian-Wolf coding and optimal non-linear estimation at the decoder, our performance gap to DWZ(R) is 0.20 dB, 0.22 dB, 0.30 dB, and 0.93 dB at 3.83 bit per sample (b/s), 1.83 b/s, 1.53 b/s, and 1.05 b/s, respectively. When 256-state 4-D trellis-coded vector quantization instead of TCQ is employed, the performance gap to DWZ(R) is 0.51 dB, 0.51 dB, 0.54 dB, and 0.80 dB at 2.04 b/s, 1.38 b/s, 1.0 b/s, and 0.5 b/s, respectively.\",\n \"Title: On packetization of embedded multimedia bitstreams\\nYear: 2001\\n\\nAbstract: We study the problem of packetizing embedded multimedia bitstreams to improve the error resilience of source (compression) codes. This problem is important because of the increasing popularity of embedded compression methodology and its suitability for scalable streaming media over IP or/and mobile IP. We study various packetization schemes against packet erasure at both low and high bit rates. Maximizing packetization efficiency for embedded bitstreams is formulated as a discrete optimization problem and globally optimal packetization (OP) algorithms are proposed under different settings. Suboptimal packetization algorithms are also devised to reduce the complexity of the OP algorithms. In order to assess their effectiveness, the proposed packetization algorithms are used to packetize embedded image and video bitstreams with simulated packet loss. Experimental results show that our OP algorithms slightly outperforms suboptimal ones. In addition to confirming the superiority of the OP algorithms, these results also provide justification of heuristic packetization methods published in the literature\",\n \"Title: Source-optimized irregular repeat accumulate codes with inherent unequal error protection capabilities and their application to scalable image transmission.\\nYear: 2006\\n\\nAbstract: The common practice for achieving unequal error protection (UEP) in scalable multimedia communication systems is to design rate-compatible punctured channel codes before computing the UEP rate assignments. This paper proposes a new approach to designing powerful irregular repeat accumulate (IRA) codes that are optimized for the multimedia source and to exploiting the inherent irregularity in IRA codes for UEP. Using the end-to-end distortion due to the first error bit in channel decoding as the cost function, which is readily given by the operational distortion-rate function of embedded source codes, we incorporate this cost function into the channel code design process via density evolution and obtain IRA codes that minimize the average cost function instead of the usual probability of error. Because the resulting IRA codes have inherent UEP capabilities due to irregularity, the new IRA code design effectively integrates channel code optimization and UEP rate assignments, resulting in source-optimized channel coding or joint source-channel coding. We simulate our source-optimized IRA codes for transporting SPIHT-coded images over a binary symmetric channel with crossover probability p. When p = 0.03 and the channel code length is long (e.g., with one codeword for the whole 512 x 512 image), we are able to operate at only 9.38% away from the channel capacity with code length 132380 bits, achieving the best published results in terms of average peak signal-to-noise ratio (PSNR). Compared to conventional IRA code design (that minimizes the probability of error) with the same code rate, the performance gain in average PSNR from using our proposed source-optimized IRA code design is 0.8759 dB when p = 0.1 and the code length is 12800 bits. As predicted by Shannon's separation principle, we observe that this performance gain diminishes as the code length increases.\",\n \"Title: A Multi-Level Design for Dirty-Paper Coding with Applications to the Cognitive Radio Channel.\\nYear: 2011\\n\\nAbstract: We propose a close-to-capacity dirty-paper coding (DPC) framework that employs multi-level low density parity-check (LDPC) codes and trellis coded quantization. The proposed coding framework is robust in the sense that it performs close to capacity in both the high and the low rate regimes. This is in contrast to existing practical DPC schemes that perform well at either one of these regimes, but not both. In order to evaluate the performance of our scheme, we consider its application to a cognitive radio channel. At a block length of 2X10(5), the designed dirty-paper coding scheme operates within 0.6, 0.58 and 0.95 dB of the theoretical limit at transmission rates of 1.5, 1.0 and 0.5 bits/sample, respectively. To the best of our knowledge, this is the best performance reported in the literature so far.\",\n \"Title: Feasibility Conditions for Interference Neutralization in Relay-Aided Interference Channel\\nYear: 2014\\n\\nAbstract: Interference neutralization (IN) is a new interference management mechanism found from and inherent in interference networks with relays. In this paper, we study the feasibility of IN for relay-aided multi-input-multi-output (MIMO) interference broadcast channel (MIMO-IBC) without symbol extension. Assuming linear transceiver with multiple amplify-and-forward relays, we consider fully connected symmetric systems, where each base station (BS), relay, and user is equipped with multiple antennas, and each user desires multiple data streams. We first present the necessary condition of generalized IN, which is the proper condition to ensure interference-free transmission with linear transceivers for general relay-aided MIMO-IBC. We then find and prove the necessary and sufficient condition of the feasibility of coordinated IN and pure IN for a class of relay-aided MIMO-IBC, where the sufficiency is proved by constructing a full rank coefficient matrix of interference-free transmission equation with sub-matrices of special structures. We show that when each BS and user has the minimal antenna configuration for data transmission, the sufficient and necessary condition for coordinated IN is the same as the necessary condition for generalized IN. When there is an arbitrary number of antennas at the BSs and users, the derived sufficient conditions give rise to the minimum relay configuration required by the coordinated IN and pure IN to support a given number of data streams without interference. Our proof sheds lights on how to use the relay resources to neutralize the interference in an efficient way. The results are applicable for both relay-aided MIMO-IBC and relay-aided interference channel (MIMO-IC).\",\n \"Title: Optimal Error Protection For Progressive Image Transmission Over Finite-State Markov Channels\\nYear: 2003\\n\\nAbstract: This paper presents a unified framework for addressing progressive image transmission over both memoryless and fading channels based on finite-state Markov channel (FSMC) models. The main advantage of using FSMC models is that they allow analytical derivation of optimal joint source-channel coding solutions in the form of unequal error protection without the burden of simulating wireless channels. Our analyses and experiments confirm that 1) FSMC models work for fading channels and 2) PSNR results obtained with FSMC models compare favorably with those published in the literature.\",\n \"Title: The effect of microarray image compression on expression-based classification\\nYear: 2009\\n\\nAbstract: Current gene-expression microarrays carry enormous amounts of information. Compression is necessary for efficient distribution\\n and storage. This paper examines JPEG2000 compression of cDNA microarray images and addresses the accuracy of classification\\n and feature selection based on decompressed images. Among other options, we choose JPEG2000 because it is the latest international\\n standard for image compression and offers lossy-to-lossless compression while achieving high lossless compression ratios on\\n microarray images. The performance of JPEG2000 has been tested on three real data sets at different compression ratios, ranging\\n from lossless to 45:1. The effects of JPEG2000 compression/decompression on differential expression detection and phenotype\\n classification have been examined. There is less than a 4% change in differential detection at compression rates as high as\\n 20:1, with detection accuracy suffering less than 2% for moderate to high intensity genes, and there is no significant effect\\n on classification at rates as high as 35:1. The supplementary material is available at http://gsp.tamu.edu/web2/Compression.\",\n \"Title: A Dirty-Paper Coding Scheme For The Cognitive Radio Channel\\nYear: 2010\\n\\nAbstract: We implement a dirty-paper coded framework for the cognitive radio channel. We assume that the cognitive user has non-causal knowledge about the primary user's transmissions. Thus the secondary receiver can employ dirty-paper coding to counter the effect of any interference from the primary user. In addition, we consider a situation where the introduction of the cognitive user should not affect the performance of the primary system - nor should the primary system have to change its encoding/decoding process. For the primary user we use a low-density parity-check code and a 4-ary pulse amplitude modulation format. For the cognitive user, we propose a dirty-paper coding scheme which employs trellis-coded quantization as the source code and an irregular repeat-accumulate code as the channel code. At a transmission rate of 1.0 bits/sample, the designed dirty-paper coding scheme operates within 1.23 dB of the theoretical limit.\",\n \"Title: Combined Source-Channel Coding of Images under Power and Bandwidth Constraints\\nYear: 2007\\n\\nAbstract: Abstract This paper proposes a framework for combined source-channel coding for a power and bandwidth constrained noisy channel. The framework is applied to progressive image transmission using constant envelope -ary phase shift key ( -PSK) signaling over an additive white Gaussian noise channel. First, the framework is developed for uncoded -PSK signaling (with ). Then, it is extended to include coded -PSK modulation using trellis coded modulation (TCM). An adaptive TCM system is also presented. Simulation results show that, depending on the constellation size, coded -PSK signaling performs 3.1 to 5.2 dB better than uncoded -PSK signaling. Finally, the performance of our combined source-channel coding scheme is investigated from the channel capacity point of view. Our framework is further extended to include powerful channel codes like turbo and low-density parity-check (LDPC) codes. With these powerful codes, our proposed scheme performs about one dB away from the capacity-achieving SNR value of the QPSK channel.\",\n \"Title: Slepian-Wolf Coded Nested Lattice Quantization for Wyner-Ziv Coding: High-Rate Performance Analysis and Code Design\\nYear: 2006\\n\\nAbstract: Nested lattice quantization provides a practical scheme for Wyner-Ziv coding. This paper examines the high-rate performance of nested lattice quantizers and gives the theoretical performance for general continuous sources. In the quadratic Gaussian case, as the rate increases, we observe an increasing gap between the performance of finite-dimensional nested lattice quantizers and the Wyner-Ziv distortion-rate function. We argue that this is because the boundary gain decreases as the rate of the nested lattice quantizers increases. To increase the boundary gain and ultimately boost the overall performance, a new practical Wyner-Ziv coding scheme called Slepian-Wolf coded nested lattice quantization (SWC-NQ) is proposed, where Slepian-Wolf coding is applied to the quantization indices of the source for the purpose of compression with side information at the decoder. Theoretical analysis shows that for the quadratic Gaussian case and at high rate, SWC-NQ performs the same as conventional entropy-coded lattice quantization with the side information available at both the encoder and the decoder. Furthermore, a nonlinear minimum mean-square error (MSE) estimator is introduced at the decoder, which is theoretically proven to degenerate to the linear minimum MSE estimator at high rate and experimentally shown to outperform the linear estimator at low rate. Practical designs of one- and two-dimensional nested lattice quantizers together with multilevel low-density parity-check (LDPC) codes for Slepian-Wolf coding give performance close to the theoretical limits of SWC-NQ\",\n \"Title: Progressive Source Coding for a Power Constrained Gaussian Channel\\nYear: 2001\\n\\nAbstract: We consider the progressive transmission of a lossy source across a power constrained Gaussian channel using binary phase-shift keying modulation. Under the theoretical assumptions of infinite bandwidth, arbitrarily complex channel coding, and lossless transmission, we derive the optimal channel code rate and the optimal energy allocation per transmitted bit. Under the practical assumptions of a l...\",\n \"Title: Progressive Video Delivery over Wideband Wireless Channels Using Space-Time Differentially Coded OFDM Systems\\nYear: 2006\\n\\nAbstract: Progressive video delivery over wireless networks is very challenging due to the time-varying nature of wireless channels and limited power in the mobile devices. This paper proposes an end-to-end architecture for multilayer progressive video delivery over space-time differentially coded orthogonal frequency division multiplexing (STDC-OFDM) systems. An input video sequence is compressed by 3D-ESCOT into a layered bitstream. We input multiple layers of the bitstream in series to a STDC-OFDM channel. Different video source layers are protected by different error protection schemes in order to achieve unequal error protection. In progressive transmission, the reconstruction quality is important not only at the target transmission rate but also at the intermediate rates. So, the error protection strategy needs to optimize the average performance over the set of intermediate rates. We propose to use progressive joint source-channel coding to generate operational transmission distortion-rate (TD-R) functions and operational transmission distortion-power (TD-P) functions for multiple layers before forming the operational transmission distortion-power-rate (TD-PR) surfaces. Lagrange multipliers are then employed on the fly to obtain the optimal power allocation and optimal rate allocation among multiple layers, subject to constraints on the total transmission rate and the total power level. Progressive joint source-channel coding offers the scalability feature to handle bandwidth variations and changes in channel conditions. By extending the rate-distortion function in source coding to the TD-PR surface in joint source-channel coding, our work can use the \\\"equal slope” argument to effectively solve the transmission rate allocation problem as well as the transmission power allocation problem for multilayer video transmission. Experiments show that our scheme achieves significant improvement over a nonoptimal system with the same total power level and total transmission rate.\",\n \"Title: Real-time unequal error protection for distortion-optimal progressive image transmission\\nYear: 2003\\n\\nAbstract: For optimal progressive transmission of an embedded image code over a noisy channel, we consider an unequal error protection strategy that minimizes the average of the expected distortion over a set of intermediate rates. In contrast to previous work, we find a near-optimal solution in real-time. For a binary symmetric channel, two state-of-the-art source coders (SPIHT and JPEG200), and a rate-compatible punctured turbo coder as a channel coder, we compare our solution to the strategy that optimizes the end-to-end performance.\",\n \"Title: Low-complexity encoding of binary quasi-cyclic codes based on Galois Fourier transform\\nYear: 2013\\n\\nAbstract: This paper presents a novel low-complexity encoding algorithm for binary quasi-cyclic (QC) codes based on matrix transformation. First, a message vector is encoded into a transformed codeword in the transform domain. Then, the transmitted codeword is obtained from the transformed codeword by the inverse Galois Fourier transform. Moreover, a simple and fast mapping is devised to post-process the transformed codeword such that the transmitted codeword is binary as well. The complexity of our proposed encoding algorithm is less than ek(n-k)log2 e+ne(log22 e+log2 e)+ n/2 elog32 e bit operations for binary codes. This complexity is much lower than its traditional complexity 2e2(n - k)k. In the examples of encoding the binary (4095, 2016) and (15500, 10850) QC codes, the complexities are 12.09% and 9.49% of those of traditional encoding, respectively.\",\n \"Title: Three-Dimensional Wavelet Coding of Video with Global Motion Compensation\\nYear: 1999\\n\\nAbstract: Three-dimensional (2D+T) wavelet coding of video using SPIHT has been shown to outperform standard predictive video coders on complex high-motion sequences, and is competitive with standard predictive video coders on simple low-motion sequences. However, on a number of typical moderate-motion se- quences characterized by largely rigid motions, 3D SPIHT performs several dB worse than motion-compensated predictive coders, because it is does not take advantage of the real physical motion underlying the scene. In this paper, we introduce global motion compensation for 3D subband video coders, and find .5{2 dB gain on sequences with dominant background motion. Our approach is a hybrid of video coding based on sprites, or mosaics, and subband coding.\",\n \"Title: Signal Processing for Multiterminal Communication Systems [from the Guest Editor]\\nYear: 2007\\n\\nAbstract: The seven articles in this special section are devoted to multi-terminal communication systems that allow the transmission of multiple sources over multiple channels. The articles explore various signal processing aspects of these systems.\",\n \"Title: Fast Trellis-Coded Color Quantization of Images\\nYear: 2002\\n\\nAbstract: We examine color quantization of images using trellis-coded quantization (TCQ) in both the RGB domain and YUV domain. Together with a simple dithering scheme, an eight-bit trellis-coded color quantizer reproduces images that are visually indistinguishable from the 24-bit originals. It can be viewed as a predictive trellis-coded color quantization scheme. We also study trellis-coded vector quantization (TCVQ) for color quantization. Our proposed TCQ-based color quantization schemes are universal in the sense that no training or look-up table is needed. The complexity of TCQ is linear with respect to image size, making trellis-coded color quantization suitable for color printing, real-time interactive graphics and window-based display environment.\",\n \"Title: A density evolution based framework for dirty paper code design using TCQ and multilevel LDPC codes\\nYear: 2012\\n\\nAbstract: We propose a density evolution based dirty-paper code design framework that combines trellis coded quantization with multi-level low-density parity-check (LDPC) codes. Unlike existing design techniques based on Gaussian approximation and EXIT charts, the proposed framework tracks the empirically collected log-likelihood ratio (LLR) distributions at each iteration, and employs density evolution and differential evolution algorithms to design each LDPC component code. In order for the approximated LLR distributions obtained using density evolution to better match the true LLR distributions, a novel decorrelator is added to the decoder to make channel LLRs and check node LLRs almost independent of each other. Simulation results show that at 1 bit per sample transmission rate, the dirty-paper codes designed using the proposed method operate within 0.53 dB of the theoretical limit, reducing the best known result (with a 0.58 dB gap to the limit) by 0.05 dB at the same complexity and block length, while this improvement can be as large as 0.21 dB (corresponding to a 0.37 dB gap to the limit) when we use higher complexity encoder/decoder with longer block length.\",\n \"Title: Lossy-to-lossless compression of medical volumetric data using three-dimensional integer wavelet transforms.\\nYear: 2003\\n\\nAbstract: We study lossy-to-lossless compression of medical volumetric data using three-dimensional (3-D) integer wavelet transforms. To achieve good lossy coding performance, it is important to have transforms that are unitary. In addition to the lifting approach, we first introduce a general 3-D integer wavelet packet transform structure that allows implicit bit shifting of wavelet coefficients to approxi...\",\n \"Title: A comparative study of DCT- and wavelet-based image coding\\nYear: 1999\\n\\nAbstract: We undertake a study of the performance difference of the discrete cosine transform (DCT) and the wavelet transform for both image and video coding, while comparing other aspects of the coding system on an equal footing based on the state-of-the-art coding techniques. The studies reveal that, for still images, the wavelet transform outperforms the DCT typically by the order of about 1 dB in peak signal-to-noise ratio. For video coding, the advantage of wavelet schemes is less obvious. We believe that the image and video compression algorithm should be addressed from the overall system viewpoint: quantization, entropy coding, and the complex interplay among elements of the coding system are more important than spending all the efforts on optimizing the transform\",\n \"Title: Error robust video transmission over wireless IP networks with multiuser detection\\nYear: 2002\\n\\nAbstract: Error control and power allocation for transmitting wireless video over CDMA networks are considered in conjunction with multiuser detection. We map a layered video bitstream to several CDMA fading channels and inject multiple source/parity layers into each of these channels at the transmitter. At the receiver, we employ a linear minimum mean-square error (MMSE) multiuser detector in the uplink and two types of blind linear MMSE detectors in the downlink, for demodulating the received data. For given constraints on the available bandwidth and transmit power, the transmitter determines the optimal power allocation among different CDMA fading channels and the optimal number of source and parity packets to send that offer the best video quality. Simulation results show a performance gain of up to 3.5 dB with joint optimization over with rate optimization only.\",\n \"Title: 3-D Face Recognition Based on Warped Example Faces\\nYear: 2007\\n\\nAbstract: In this paper, we describe a novel 3-D face recognition scheme for 3-D face recognition that can automatically identify faces from range images, and is insensitive to holes, facial expression, and hair. In our scheme, a number of carefully selected range images constitute a set of example faces, and another range image is chosen as a ldquogeneric face.rdquo The generic face is then warped to match each of the example faces in the least mean square sense. Each such warp is specified by a vector of displacement values. In feature extraction operation, when a target face image comes in, the generic face is warped to match it. The geometric transformation used in the warping is a linear combination of the example face warping vectors. The coefficients in the linear combination are adjusted to minimize the root mean square error. After the matching process is complete, the coefficients of the composite warp are used as features and passed to a Mahalanobis-distance-based classifier for face recognition. Our technique is tested on a data set containing more than 600 range images. Experimental results in the access-control scenario show the effectiveness of the extracted features.\",\n \"Title: Support-driven sparse coding for face hallucination\\nYear: 2013\\n\\nAbstract: By incorporating the prior of positions, position patch based face hallucination methods can produce high-quality results and save computation time. Given a low-resolution face image, the key issue of these methods is how to encode the input low-resolution patch. However, due to stability and accuracy issues, the coding approaches proposed so far are not satisfactory. In this paper, we present a novel sparse coding method via exploiting the support information on the coding coefficients. In particular, the support information is characterized by the locality of the image patch manifold, which has been shown to be critical in data representation and analysis. According to the distances between the input patch and bases in the dictionary, we first assign different weights to the coding coefficients and then obtain the coding coefficients by solving a weighted sparse problem. Our proposed method exploits the non-linear manifold structure of patch samples and the sparse property of the redundant data, leading to stable and accurate representation. Experiments on commonly used databases demonstrate that our method outperforms state of the art.\",\n \"Title: Wavelet image coding using trellis coded space-frequency quantization\\nYear: 1998\\n\\nAbstract: The progress in wavelet image coding have brought the field into its maturity. Major developments in the process are rate-distortion (R-D) based wavelet packet transformation, zerotree quantization, subband classification and trellis-coded quantization, and sophisticated context modeling in entropy coding. Drawing from past experience and recent in sights, we propose a new wavelet image coding technique with trellis coded space-frequency quantization (TCSFQ). TCSFQ aims to explore space-frequency characterizations of wavelet image representations via R-D optimized zerotree pruning, trellis-coded quantization, and context modeling in entropy coding. Experiments indicate that the TCSFQ coder achieves twice as much compression as the baseline JPEG coder does at the same peak signal to noise ratio (PSNR), making it better than all other coders described in the literature.\",\n \"Title: Progressive Image Transmission over Space-Time Coded OFDM-Based MIMO Systems with Adaptive Modulation\\nYear: 2006\\n\\nAbstract: This paper considers a progressive image transmission system over wireless channels by combining joint source-channel coding (JSCC), space-time coding, and orthogonal frequency division multiplexing (OFDM). The BER performance of the space-time coded OFDM-based MIMO system based on a newly built broadband MIMO fading model is first evaluated by assuming perfect channel state information at the receiver for coherent detection. Then, for a given average SNR (hence, BER), a fast local search algorithm is applied to optimize the unequal error protection design in JSCC, subjected to fixed total transmitted energy for various constellation sizes. This design allows the measurement of the expected reconstructed image quality. With this end-to-end system performance evaluation, an adaptive modulation scheme is proposed to pick the constellation size that offers the best reconstructed image quality for each average SNR. Simulation results of practical image transmissions confirm the effectiveness of our proposed adaptive modulation scheme.\",\n \"Title: Wavelet-based compression of M-FISH images.\\nYear: 2005\\n\\nAbstract: Multiplex fluorescence in situ hybridization (M-FISH) is a recently developed technology that enables multi-color chromosome karyotyping for molecular cytogenetic analysis. Each M-FISH image set consists of a number of aligned images of the same chromosome specimen captured at different optical wavelength. This paper presents embedded M-FISH image coding (EMIC), where the foreground objects/chromo...\",\n \"Title: Distributed Source Coding for Sensor Networks\\nYear: 2004\\n\\nAbstract: In recent years, sensor research has been undergoing a quiet revolution, promising to have a significant impact throughout society that could quite possibly dwarf previous milestones in the information revolution. Realizing the great promise of sensor networks requires more than a mere advance in individual technologies. It relies on many components working together in an efficient, unattended, co...\",\n \"Title: A new rate allocation scheme for progressive fine granular scalable coding\\nYear: 2001\\n\\nAbstract: We examine the enhancement layer rate allocation problem in progressive fine granular scalable (PFGS) coding. The problem arises from the fact that different frames in the enhancement layer have different rates in PFGS coding. A joint operational rate-distortion (R-D) function for a multi-frame group is first established in enhancement layer PFGS coding, followed by experiments to verify its validity using real test sequences. The optimal rate allocation among frames in the group for the enhancement layer PFGS coding is then given based on the R-D function. Coding results show that, compared to uniform bit allocation, the new bit allocation scheme not only makes the quality variation in decoded video frames smoother, but also improves the coding efficiency of PFGS coding by up to 1.0 dxxB in PSNR. Furthermore, the new scheme has very low complexity, making it suitable for video multicast applications\",\n \"Title: Cascaded differential and wavelet compression of chromosome images.\\nYear: 2002\\n\\nAbstract: This paper proposes a new method for chromosome image compression based on an important characteristic of these images: the regions of interest (ROIs) to cytogeneticists for evaluation and diagnosis are well determined and segmented. Such information is utilized to advantage in our compression algorithm, which combines lossless compression of chromosome ROIs with lossy-to-lossless coding of the re...\",\n \"Title: Microarray BASICA: background adjustment, segmentation, image compression and analysis of microarray images\\nYear: 2004\\n\\nAbstract: This paper presents microarray BASICA: an integrated image processing tool for background adjustment, segmentation, image compression, and analysis of cDNA microarray images. BASICA uses a fast Mann-Whitney test-based algorithm to segment cDNA microarray images, and performs postprocessing to eliminate the segmentation irregularities. The segmentation results, along with the foreground and background intensities obtained with the background adjustment, are then used for independent compression of the foreground and background. We introduce a new distortion measurement for cDNA microarray image compression and devise a coding scheme by modifying the embedded block coding with optimized truncation (EBCOT) algorithm (Taubman, 2000) to achieve optimal rate-distortion performance in lossy coding while still maintaining outstanding lossless compression performance. Experimental results show that the bit rate required to ensure sufficiently accurate gene expression measurement varies and depends on the quality of cDNA microarray images. For homogeneously hybridized cDNA microarray images, BASICA is able to provide from a bit rate as low as 5 bpp the gene expression data that are Open image in new window % in agreement with those of the original 32 bpp images.\",\n \"Title: Error-resilient unequal error protection of fine granularity scalable video bitstreams\\nYear: 2006\\n\\nAbstract: This paper deals with the optimal packet loss protection issue for streaming the fine granularity scalable (FGS) video bitstreams over IP networks. Unlike many other existing protection schemes, we develop an error-resilient unequal error protection (ER-UEP) method that adds redundant information optimally for loss protection and, at the same time, cancels completely the dependency among bitstream after loss recovery. In our ER-UEP method, the FGS enhancement-layer bitstream is first packetized into a group of independent and scalable data packets. Parity packets, which are also scalable, are then generated. Unequal protection is finally achieved by properly shaping the data packets and the parity packets. We present an algorithm that can optimally allocate the rate budget between data packets and parity packets, together with several simplified versions that have lower complexity. Compared with conventional UEP schemes that suffer from bit contamination (caused by the bit dependency within a bitstream), our method guarantees successful decoding of all received bits, thus leading to strong error-resilience (at any fixed channel bandwidth) and high robustness (under varying and/or unclean channel conditions).\",\n \"Title: Chromosome image enhancement using multiscale differential operators.\\nYear: 2003\\n\\nAbstract: Chromosome banding patterns are very important features for karyotyping, based on which cytogenetic diagnosis procedures are conducted. Due to cell culture, staining, and imaging conditions, image enhancement is a desirable preprocessing step before performing chromosome classification. In this paper, we apply a family of differential wavelet transforms (Wang and Lee, 1998), (Wang, 1999) for this ...\",\n \"Title: Edge-preserving interpolation for down/up sampling-based depth compression\\nYear: 2012\\n\\nAbstract: Preserving the edges in depth compression is important for improving the synthesized view quality, this paper presents a novel edge-preserving depth up-sampling method for down/up sampling-based depth coding using both the texture and depth information. We take into account the edge similarity between depth maps and their corresponding texture images as well as the structural similarity among depth maps to build a weight model. Based on the weight model, the optimal MMSE up-sampling coefficients are estimated from the local covariance coefficients of the down-sampled depth map. Experimental results show that our proposed interpolation method for down/up sampling-based depth coding improves both the coding efficiency and synthesized view quality.\",\n \"Title: Near-Capacity Dirty-Paper Code Design: A Source-Channel Coding Approach\\nYear: 2009\\n\\nAbstract: This paper examines near-capacity dirty-paper code designs based on source-channel coding. We first point out that the performance loss in signal-to-noise ratio (SNR) in our code designs can be broken into the sum of the packing loss from channel coding and a modulo loss, which is a function of the granular loss from source coding and the target dirty-paper coding rate (or SNR). We then examine practical designs by combining trellis-coded quantization (TCQ) with both systematic and nonsystematic irregular repeat-accumulate (IRA) codes. Like previous approaches, we exploit the extrinsic information transfer (EXIT) chart technique for capacity-approaching IRA code design; but unlike previous approaches, we emphasize the role of strong source coding to achieve as much granular gain as possible using TCQ. Instead of systematic doping, we employ two relatively shifted TCQ codebooks, where the shift is optimized (via tuning the EXIT charts) to facilitate the IRA code design. Our designs synergistically combine TCQ with IRA codes so that they work together as well as they do individually. By bringing together TCQ (the best quantizer from the source coding community) and EXIT chart-based IRA code designs (the best from the channel coding community), we are able to approach the theoretical limit of dirty-paper coding. For example, at 0.25 bit per symbol (b/s), our best code design (with 2048-state TCQ) performs only 0.630 dB away from the Shannon capacity.\",\n \"Title: Space-frequency quantization for a space-varying wavelet packet image coder\\nYear: 1995\\n\\nAbstract: We introduce a new image coding algorithm which exploits the idea of space-varying wavelet packets, where the best filter bank representation is chosen from a large library. The filter bank tree representations in the library are free to vary in structure over different segments of the image, and a fast search algorithm is given. In addition we employ the idea of space-frequency quantization, which is a rate-distortion optimized extension of the zero-tree wavelet coder of Shapiro to wavelet packets. The coder thus adaptively chooses the representation to suit the image and adaptively chooses the quantization to suit the representation. We present coding results that confirm the excellent performance of the scheme\",\n \"Title: A Low-Complexity Encoding of Quasi-Cyclic Codes Based on Galois Fourier Transform\\nYear: 2013\\n\\nAbstract: The encoding complexity of a general (en,ek) quasi-cyclic code is O[(e^2)(n-k)k]. This paper presents a novel low-complexity encoding algorithm for quasi-cyclic (QC) codes based on matrix transformation. First, a message vector is encoded into a transformed codeword in the transform domain. Then, the transmitted codeword is obtained from the transformed codeword by the inverse Galois Fourier transform. For binary QC codes, a simple and fast mapping is required to post-process the transformed codeword such that the transmitted codeword is binary as well. The complexity of our proposed encoding algorithm is O[e(n-k)k] symbol operations for non-binary codes and O[ek(n-k)(log_2 e)] bit operations for binary codes. These complexities are much lower than their traditional counterpart O[(e^2)(n-k)k]. For example, our complexity of encoding a 64-ary (4095,2160) QC code is only 1.59% of that of traditional encoding, and our complexities of encoding the binary (4095, 2160) and (8176, 7154) QC codes are respectively 9.52% and 1.77% of those of traditional encoding. We also study the application of our low-complexity encoding algorithm to one of the most important subclasses of QC codes, namely QC-LDPC codes, especially when their parity-check matrices are rank deficient.\",\n \"Title: Error robust scalable audio streaming over wireless IP networks\\nYear: 2004\\n\\nAbstract: Streaming high-fidelity audio over wireless Internet protocol (IP) networks is a challenging task because the networks present not only packet losses, but also residual bit errors. These losses and errors have severe adverse effect on the compressed audio bitstream. To solve this problem, this paper introduces error resilience in conjunction with error protection for scalable audio streaming over wireless networks. Specifically, error resilience is achieved by performing bitstream data partitioning and reversible variable length coding in the audio coder. Error protection is provided by layered product channel code to simultaneously handle packet losses and residual bit errors. Both the row and column codes of the product code provide unequal error protection for different layers of the audio bitstream by considering the characteristics of the scalable audio. Rate-distortion optimization is performed to determine the best source-channel coding tradeoff that minimizes the average expected end-to-end distortion. Simulation results demonstrate the effectiveness of our proposed approach.\",\n \"Title: Achieving the degrees of freedom of relay-aided interference broadcast channels\\nYear: 2012\\n\\nAbstract: This paper studies the degrees of freedom (DoF) of relay-aided interference broadcast channels and the relay resource to achieve them. We show that, with the aid of half-duplex relays, a G-cell system can achieve GMBS/2 DoF, where MBS is the number of transmit antennas in each cell. By studying the interference-free constraints, we obtain a lower bound of the relay resource that ensures interference-free transmission. Instead of directly solving the complicated multivariate problem with cubic interference-free constraints, we propose to relax the problem to linear equations by randomly initiating certain variables, and derive an achievable bound on relay resource. Numerical results show that the relay-aided interference broadcast channels require less relay resource than relay-aided interference channels and transmission protocol has large impact on the required resources.\",\n \"Title: Distributed Joint Source-Channel Coding of Video Using Raptor Codes\\nYear: 2007\\n\\nAbstract: Extending recent works on distributed source coding, this paper considers distributed source-channel coding and targets at the important application of scalable video transmission over wireless networks. The idea is to use a single channel code for both video compression (via Slepian-Wolf coding) and packet loss protection. First, we provide a theoretical code design framework for distributed joint source-channel coding over erasure channels and then apply it to the targeted video application. The resulting video coder is based on a cross-layer design where video compression and protection are performed jointly. We choose Raptor codes - the best approximation to a digital fountain - and address in detail both encoder and decoder designs. Using the received packets together with a correlated video available at the decoder as side information, we devise a new iterative soft-decision decoder for joint Raptor decoding. Simulation results show that, compared to one separate design using Slepian-Wolf compression plus erasure protection and another based on FGS coding plus erasure protection, the proposed joint design provides better video quality at the same number of transmitted packets. Our work represents the first in capitalizing the latest in distributed source coding and near-capacity channel coding for robust video transmission over erasure channels.\",\n \"Title: Audio coding and image denoising based on the nonuniform modulated complex lapped transform\\nYear: 2005\\n\\nAbstract: Xiong and Malvar recently introduced a nonuniform modulated complex lapped transform (NMCLT) with good time-localization and controllable frequency resolution by using an oversampled nonuniform filter bank to generate its real and the imaginary components. In this paper, we first show that oversampling in the NMCLT is not necessary in theory but a by-product of fast implementation in practice. We also point out that the amount of oversampling, which can be flexibly controlled, depends on the application. We then describe in detail the implementation of the inverse transform, which was not addressed clearly by Xiong and Malvar. We present the first applications of the NMCLT to audio coding and image denoising. A scalable audio coder has been implemented by controlling the amount of oversampling and exploiting redundancy among the NMCLT coefficients via predictive coding. Experimental results show that the audio coder reduces pre-echoes and improves the sound quality of audio clips with transient sounds. A simple denoising algorithm based on the NMCLT has also been devised to provide images with better visual quality than those obtained with wavelet-based soft thresholding.\",\n \"Title: Distributed joint source-channel coding of video\\nYear: 2005\\n\\nAbstract: Based on recent works on source-channel coding for Wyner-Ziv coding, we consider the case with noisy channel in Wyner-Ziv coding and address distributed joint source-channel coding, while targeting at the important application of video transmission over packet erasure channels. The idea is to use a single channel code for both Slepian-Wolf coding (or source coding with side information at the decoder) and erasure protection. We choose Raptor codes - the best approximation to a digital fountain - for the targeted application and study both encoder and decoder designs under the new setting of distributed joint source-channel coding. Our work represents the first in capitalizing the latest in distributed source coding (e.g., Wyner-Ziv video coding) and near-capacity channel coding (e.g., fountain codes) for robust video transmission over erasure channels.\",\n \"Title: Flexible tree-structured signal expansions using time-varying wavelet packets\\nYear: 1997\\n\\nAbstract: Addresses the problem of finding the best time-varying filter bank tree-structured representation for a signal. The tree is allowed to vary at regular intervals, and the spacing of these changes can be arbitrarily short. The question of how to choose tree-structured representations of signals based on filter banks is considered. Wavelets and their adaptive version, known as wavelet packets, represent one approach that is popular. Wavelet packets are subband trees where the tree is chosen to match the characteristics of the signal. Variations where the tree varies over time have been proposed as the double tree and the time-frequency tree algorithms. Time-variation adds a further level of adaptivity. In all of the approaches proposed so far, the tree must be either fixed for the whole duration of the signal or fixed for its dyadic subintervals. The solution that we propose, as it allows more flexible variation, is an advance on the wavelet packet algorithm, the double tree algorithm, and the recently proposed time-frequency tree algorithm. Our solution is based on casting it in a dynamic programming (DP) setting. Focusing on compression applications, we use a Lagrangian cost of distortion +λ×rate as the objective function and explain our algorithm in detail, pointing out its relation to existing approaches to the problem. We demonstrate that the new algorithm indeed searches a larger library of representations than previously possible and that overcoming the constraint of dyadic time segmentations gives a significant improvement in practice\",\n \"Title: Slepian-Wolf coded nested quantization (SWC-NQ) for Wyner-Ziv coding: performance analysis and code design\\nYear: 2004\\n\\nAbstract: This paper examines the high-rate performance of low-dimensional nested lattice quantizers for the quadratic Gaussian Wyner-Ziv problem, using a pair of nested lattices with the same dimensionality. As the rate increases, the gap increases between the performances of low dimensional nested lattice quantizers and the Wyner-Ziv rate-distortion function. This gap is due to the relatively weak channel coding component (or coarse lattice) in the nested lattice pair. To enhance the lattice channel code and boost the overall performance, Slepian-Wolf coding is applied to the quantization indices to achieve further compression. Thereby a Wyner-Ziv coding paradigm is introduced using Slepian-Wolf coded nested lattice quantization (SWC-NQ). Theoretical analysis and simulation results show that, for the quadratic Gaussian source and at high rate, SWC-NQ performs the same as traditional entropy-constrained lattice quantization with side information available at both the encoder and decoder.\",\n \"Title: Distributed Compression of Binary Sources Using Conventional Parallel and Serial Concatenated Convolutional Codes\\nYear: 2003\\n\\nAbstract: We show how conventional parallel (turbo) and serial concatenated convolutionalcodes can be used to compress close to the Slepian-Wolf limit ofr correlated binarysources.Conventional refers to codes already used in channel coding.Focusing on the asymmetric case of compression of an equiprobable memoryless binary source withside information at the decoder, the approach is based on modeling the correlation asa channel and using syndromes.The encoding and decoding procedures are explainedin detail.The performance achieved is seen to be better than recently publishedresults using nonconventional turbo codes and very close to the Slepian-Wolf limit.\",\n \"Title: Nested Turbo Codes for the Costa Problem.\\nYear: 2007\\n\\nAbstract: Abstract—Driven by applications in data-hiding, MIMO broadcast channel coding, precoding for interference cancella- tion, and transmitter cooperation in wireless networks, Costa coding has lately become a very active research area. In this paper, we first offer code design guidelines in terms of source- channel coding for algebraic binning. We then address practical code design based on nested lattice codes and propose nested turbo codes using turbo-like trellis-coded quantization (TCQ) for source coding and turbo trellis-coded modulation (TTCM) for channel coding. Compared to TCQ, turbo-like TCQ offers structural similarity between the source and channel coding components, leading to more efficient nesting with TTCM and better source coding performance. Due to the difference in effective dimensionality between turbo-like TCQ and TTCM, there is a performance tradeoff between these two components when they are nested together, meaning that the performance of turbo-like TCQ worsens as the TTCM code becomes stronger and vice versa. Optimization of this performance tradeoff leads to our code design that outperforms existing TCQ/TCM and TCQ/TTCM constructions and exhibits a gap of 0.94, 1.42 and 2.65 dB to the Costa capacity at 2.0, 1.0, and 0.5 b/s, respectively. Index Terms—Costa coding, nested lattice codes, trellis-coded\",\n \"Title: Wyner–Ziv Video Compression and Fountain Codes for Receiver-Driven Layered Multicast\\nYear: 2007\\n\\nAbstract: The increasing popularity of video streaming applications that distribute data to a large number of clients motivates the design of reliable multimedia delivery systems capable of adapting to diverse transmission conditions. Receiver-driven layered multicast (RLM) efficiently addresses the issue of heterogeneity in clients' available bandwidths and packet loss rates by shifting rate control to the receiver side. We propose a system for RLM over the Internet and 3G wireless networks based on layered Wyner-Ziv video coding and digital fountain codes. Layered Wyner-Ziv video coding improves robustness to packet loss compared to current scalable video coders, such as MPEG-4 FGS coder, while generating a scalable output bit stream. Digital fountain codes are near-capacity erasure protection codes that are ideally suited for multicast applications due to their rateless property. By combining an error-resilient Wyner-Ziv video coder and rateless fountain codes, our system allows reliable video multicast to an arbitrary number of heterogeneous receivers without the requirement of feedback channels. Simulation results show performance improvements over a previous scheme that exploits multiple description and layered coding.\",\n \"Title: Facial Feature Extraction from Range Images using a 3D Morphable Model\\nYear: 2007\\n\\nAbstract: In this paper, a novel scheme is introduced for human facial feature extraction. Unlike previous methods that fit a 3D morphable model to 2D intensity images, our scheme utilizes 3D range images to extract features without requiring manually-defined initial landmark points. A linear transformation is used to achieve the mapping between the 3D model and a 3D range image, which makes the computation simple and fast. Moreover, our scheme is robust to the illumination and pose variations. In addition to features from range images, extra features can be obtained by examining optional 2D texture images. Using our scheme, we can also perform automatic eye/mouth corner localization. Experimental results show the high accuracy and robustness of our scheme.\",\n \"Title: Reliable Versus Unreliable Transmission For Energy Efficient Transmission In Relay Networks\\nYear: 2012\\n\\nAbstract: A network code is said to be reliable when all transmissions in the network are (deterministic) functions of the source messages; well-known examples include decode-forward for relay networks. It is said to be unreliable when transmissions depend on the noise realization at nodes; examples include compress-forward and amplify-forward. The deterministic capacity of a network is defined as the supremum of the rates achievable by reliable codes. In this paper we derive the deterministic capacity of some relay networks in the low power regime. The resulting energy per bit is then compared with the one achievable by arbitrary transmission.\",\n \"Title: Compression of M-FISH images using 3-D ESCOT\\nYear: 2001\\n\\nAbstract: This paper introduces a lossy to lossless coding technique for compression of multitarget fluorescence in situ hybridization (M-FISH) images using 3-D embedded subband coding with optimal truncation (3-D ESCOT) (Xu et al.). With a lifting-based integer wavelet decomposition, 3-D ESCOT achieves about twice as much compression as Lempel-Ziv (WinZip) coding-the current method for archiving M-FISH images. The lossy coding performance of 3-D ESCOT is significantly better than that of 2-D based JPEG-2000\",\n \"Title: Memory-constrained 3-D wavelet transform for video coding without boundary effects\\nYear: 2002\\n\\nAbstract: Three-dimensional (3-D) wavelet-based scalable video coding provides a viable alternative to standard MC-DCT coding. However, many current 3-D wavelet coders experience severe boundary effects across group of pictures (GOP) boundaries. This paper proposes a memory-efficient transform technique via lifting that effectively computes wavelet transforms of a video sequence continuously on the fly, thus eliminating the boundary effects due to limited length of individual GOPs. Coding results show that the proposed scheme completely eliminates the boundary effects and gives superb video playback quality.\",\n \"Title: Low-Complexity Encoding of Quasi-Cyclic Codes Based on Galois Fourier Transform\\nYear: 2014\\n\\nAbstract: This paper presents two novel low-complexity encoding algorithms for quasi-cyclic (QC) codes based on Galois Fourier transform. The key idea behind them is making use of the block diagonal structure of the transformed generator matrix. The first one, named encoding by Galois Fourier transform, is equivalent to the fast implementations of the traditional encoding by Galois Fourier transform. The second one, named encoding in the transform domain (ETD), requires much less computational complexity for encoding binary QC codes. It skips the first step of the first algorithm and applies post-processing to save a large number of Galois field multiplications. Its application to QC-LDPC codes is also studied in this paper. Particularly, the hardware cost of the ETD for RS-based LDPC codes can be greatly reduced by short linear-feedback shift registers.\",\n \"Title: On the Minimum Energy of Sending Correlated Sources Over the Gaussian MAC\\nYear: 2014\\n\\nAbstract: In this paper, we investigate the minimum energy of transmitting correlated sources over the Gaussian multiple-access channel. Compared to other works on joint source-channel coding, we consider the fundamental problem of the minimum transmission energy, where the source and channel bandwidths are not naturally matched. Different models of correlated sources are studied. We first treat lossy transmission of Gaussian sources, including multiterminal sources and CEO sources. We then consider lossless transmission of correlated binary sources. In all cases, we lower bound the minimum energy using a cut-set argument that couples transmission energy and the distortions for the Gaussian cases (or source entropy for the discrete case). For the achievable schemes, separate source and channel coding and uncoded transmission are studied as benchmarks. In addition, we show that hybrid digital/analog transmission achieves the best known energy efficiency.\",\n \"Title: Multiterminal source coding: Theory, code design and applications\\nYear: 2011\\n\\nAbstract: Summary form only given. Distributed source coding (DSC) considers the problem of separate compression and joint decompression of multiple correlated sources. Berger and Tung first introduced the multiterminal (MT) source coding problem and studied the region of all possible encoder rate tuples such that the sources are reconstructed under distortion constraints. One can loosely view MT source coding as the lossy version of Slepian-Wolf coding. Applications of MT source coding include distributed video sensor networks and MT/multiview video coding for camera arrays. Despite recent progresses, finding the sum-rate bound of quadratic Gaussian MT source coding with more than two terminals is still an open problem. In this talk, I will present our recent theoretical results on quadratic Gaussian MT source coding, limit-approaching code designs, and MT video coding (including the case with depth camera assistance).\",\n \"Title: Multiresolutional encoding and decoding in embedded image and video coders\\nYear: 1998\\n\\nAbstract: We address multiresolutional encoding and decoding within the embedded zerotree wavelet (EZW) framework for both images and video. By varying a resolution parameter, one can obtain decoded images at different resolutions from one single encoded bitstream, which is already rate scalable for EZW coders. Similarly one can decode video sequences at different rates and different spatial and temporal resolutions from one bitstream. Furthermore, a layered bitstream can be generated with multiresolutional encoding, from which the higher resolution layers can be used to increase the spatial/temporal resolution of the images/video obtained from the low resolution layer. In other words, we have achieved full scalability in rate and partial scalability in space and time. This added spatial/temporal scalability is significant for emerging multimedia applications such as fast decoding, image/video database browsing, telemedicine, multipoint video conferencing, and distance learning\",\n \"Title: Achieving the degrees of freedom of 2×2×2 interference network with arbitrary antenna configurations\\nYear: 2014\\n\\nAbstract: This paper studies the degrees of freedom (DoF) region of the 2 × 2 × 2 interference network, which is comprised of two sources, two relays and two destinations, each with arbitrary number of antennas. We prove that with linear transceivers, the cut-set outer bound can be achieved without any symbol extensions, except for one specific system setup, which has one-DoF gap to the cut-set bound. We show that to achieve the outer-bound, the transceivers include interference avoidance, cancelation, neutralization and alignment, depending on the antenna configuration.\",\n \"Title: Nonlocal image denoising via collaborative spatial-domain LMMSE estimation\\nYear: 2014\\n\\nAbstract: In recent years, the performance of image denoising has been boosted drastically by nonlocal algorithms and sparse coding techniques. In this paper, we also take a nonlocal approach to image denoising and formulate the problem as one of collaborative LMMSE estimation from grouped image patches. We show that our optimal LMMSE solution amounts to shrinking the singular values of the matrix representation of the grouped image patches. This interpretation of our solution allows us to relate our estimation-theoretic approach to other nonlocal algorithms and sparse coding techniques in the literature. In addition, we develop an iterative algorithm to find the best LMMSE estimate. Experimental results show that our proposed denoising algorithm achieves better PSNR and subjective performance than the state of the art.\",\n \"Title: Depth-based human body enhancement in the infrared video\\nYear: 2014\\n\\nAbstract: Based on the depth information acquired by the popular RGBD camera such as Kinect, the human body image areas in the infrared video can be selectively enhanced. In this paper, we firstly utilized the Optimal Contrast-Tone Mapping (OCTM) method instead of Histogram Equalization (HE) method to make a good contrast balance for the infrared video image acquired in a low illumination condition. Secondly, we used multiple iterations of the Level Set algorithm to improve the human body silhouette which initially recognized by the RGBD camera in each infrared frame. Finally, in order to improve the image quality of the human body area in each infrared frame, a fast bilateral filter had been employed to eliminate the spot noise while maintaining good edge features. Experimental results show that the proposed method can effectively enhance the human subjects in the infrared video images.\",\n \"Title: Global motion compensation for low bitrate video coding\\nYear: 1997\\n\\nAbstract: A global motion compensation (GMC) scheme is described and implemented for low bitrate coding. Experiments show that GMC gives excellent coding results. When coupled with the H.263 low bitrate video coding standard, GMC is capable of achieving up to 27% bitrate saving (or 1.8 dB gain in PSNR) for a high motion sequence such as Stefan. For a moderate motion sequence such as Cost-guard, we obtained an 8% bitrate saving over H.263 at the same quality using GMC\",\n \"Title: Joint product code optimization for scalable multimedia transmission over wireless channels\\nYear: 2002\\n\\nAbstract: State-of-the-art systems for the transmission of images over wireless channels generate an embedded bitstream and protect it with a product code where the row code is a concatenation of an outer cyclic redundancy check (CRC) code and an inner rate-compatible punctured convolutional (RCPC) code, and the column code is a Reed-Solomon (RS) code. In previous works, the product code was optimized by searching for the best RS protection for each RCPC code rate. We present a local search algorithm that jointly optimizes the RS and the RCPC codes. Experimental results show that our algorithm provides an approximately optimal solution, while its time complexity is much lower than that of the previous works.\",\n \"Title: Compression of binary sources with side information at the decoder using LDPC codes\\nYear: 2002\\n\\nAbstract: We show how low-density parity-check (LDPC) codes can be used to compress close to the Slepian-Wolf limit for cor- related binary sources. Focusing on the asymmetric case of com- pression of an equiprobable memoryless binary source with side information at the decoder, the approach is based on viewing the correlation as a channel and applying the syndrome concept. The encoding and decoding procedures are explained in detail. The per- formance achieved is seen to be better than recently published re- sults using turbo codes and very close to the Slepian-Wolf limit.\",\n \"Title: Progressive trellis-coded space-frequency quantization for wavelet image coding\\nYear: 2002\\n\\nAbstract: This paper addresses progressive wavelet image coding within the trellis-coded space-frequency quantization (TCSFQ) framework (Xiong et al., 1999). A method similar to that in Bilgin et al. (1999), is used to approximately invert TCSFQ when decoding at rates lower than the encoding rate. Our experiments show that the loss incurred for progressive transmission is within 1 dB in peak signal-to-noise ratio and that the progressive coding performance of TCSFQ is competitive with that of the celebrated SPIHT coder (Said et al., 1996) at all rates\",\n \"Title: A distributed source coding technique for correlated images using turbo-codes\\nYear: 2002\\n\\nAbstract: The Slepian-Wolf (1973) theorem states that the output of two correlated sources can be compressed to the same extent without loss, whether they communicate with each other or not, provided that decompression takes place at a joint decoder. We present a distributed source coding scheme for correlated images which uses modulo encoding of pixel values and encoding (compression) of the resulting symbols with binary and nonbinary turbo-codes, so that larger rate savings than using modulo encoding. alone are achieved, practically without loss.\",\n \"Title: Joint source-channel coding of binary sources with side information at the decoder using IRA codes\\nYear: 2002\\n\\nAbstract: We use systematic irregular repeat accumulate (IRA) codes as source-channel codes for the transmission of an equiprob- able memoryless binary source with side information at the de- coder. A special case of this problem is joint source-channel coding for a nonequiprobable memoryless binary source. The theoretical limits of this problem are given by combining the Slepian-Wolf theorem, the source entropy in the special case, with the channel capacity. The approach is based on viewing the correlation between the binary source output and the side information as a separate channel or an enhancement of the original channel. The joint source-channel encoding, decoding and code design procedures are explained in detail. The simulated performance results are better than the recently published solutions using turbo codes and very close to the theoretical limit.\",\n \"Title: An efficient algorithm to find a jointly optimal time-frequency segmentation using time-varying filter banks\\nYear: 1995\\n\\nAbstract: We examine the question of how to choose a time-varying filter bank representation for a signal which is optimal with respect to an additive cost function. We present in detail an efficient algorithm for the Haar filter set which finds the optimal basis, given the constraint that the time and frequency segmentations are binary. Extension to multiple dimensions is simple, and the use of arbitrary filter sets is also possible. We verify that the algorithm indeed produces a lower cost representation than any of the wavelet packet representations for compression of images using a simple rate-distortion cost.\",\n \"Title: Adaptive transforms for image coding using spatially varying wavelet packets\\nYear: 1996\\n\\nAbstract: We introduce a novel, adaptive image representation using spatially varying wavelet packets (WPs), Our adaptive representation uses the fast double-tree algorithm introduced previously (Herley et al., 1993) to optimize an operational rate-distortion (R-D) cost function, as is appropriate for the lossy image compression framework. This involves jointly determining which filter bank tree (WP frequency decomposition) to use, and when to change the filter bank tree (spatial segmentation). For optimality, the spatial and frequency segmentations must be done jointly, not sequentially. Due to computational complexity constraints, we consider quadtree spatial segmentations and binary WP frequency decompositions (corresponding to two-channel filter banks) for application to image coding. We present results verifying the usefulness and versatility of this adaptive representation for image coding using both a first-order entropy rate-measure-based coder as well as a powerful space-frequency quantization-based (SPQ-based) wavelet coder introduced by Xiong et al. (1993).\",\n \"Title: On dualities in multiterminal coding problems\\nYear: 2006\\n\\nAbstract: It has been shown recently that under certain conditions there exist dualities between different multiterminal (MT) source and channel coding problems. Following these results, we study lossless MT source coding and deterministic MT channel coding problems and point out different dualities between them. In particular, we show that there exists a functional duality between a Slepian-Wolf (SW) coding problem and a deterministic broadcast channel (DBC) coding problem and between a lossless multiple-description (MD) coding problem and a deterministic multiple-access channel (DMAC) coding problem. In analogy to the duality established between DBC and DMAC coding problems, we further propose a similar duality between SW and lossless MD coding problems; in this way, we form a closed \\\"duality loop\\\" of four MT coding problems, which imposes the existence of a single common rate point in the achievable rate regions of all four dual problems. We also consider duality in zero-error MT coding and shed light on practical code design with an example. Finally, extension to the case with only one lossless/deterministic component in the source/channel coding problem is provided.\",\n \"Title: On Practical Design for Joint Distributed Source and Network Coding\\nYear: 2009\\n\\nAbstract: This paper considers the problem of communicating correlated information from multiple source nodes over a network of noiseless channels to multiple destination nodes, where each destination node wants to recover all sources. The problem involves a joint consideration of distributed compression and network information relaying. Although the optimal rate region has been theoretically characterized, it was not clear how to design practical communication schemes with low complexity. This work provides a partial solution to this problem by proposing a low-complexity scheme for the special case with two sources whose correlation is characterized by a binary symmetric channel. Our scheme is based on a careful combination of linear syndrome-based Slepian-Wolf coding and random linear mixing (network coding). It is in general suboptimal; however, its low complexity and robustness to network dynamics make it suitable for practical implementation.\",\n \"Title: On Outage Capacity in the Low Power Regime\\nYear: 2012\\n\\nAbstract: This paper derives a formula for the wideband slope for outage capacity and consider its application to some specific wireless channels. For the broadcast channel, the formula indicates that superposition is always superior to time-division multiple access (TDMA). On the other hand, for the interference channel, we show that TDMA is better than superposition for most realistic situations.\",\n \"Title: Rateless coded hybrid amplify/decode-forward cooperation for wireless multicast\\nYear: 2012\\n\\nAbstract: We consider a cooperative wireless multicast channel with no channel state information available at the transmitters, and where all wireless links undergo independent identically distributed quasi-static Rayleigh fading. For cooperation, we propose a rateless coded approach and identify its benefits over a conventional fixed-rate two-hop strategy. In addition to providing robust communications under fading conditions, rateless coding is able to exploit the cooperation benefits to a greater degree. A hybrid rateless coded cooperation scheme is proposed which employs amplify-and-forward (AF) in conjunction with decode-and-forward (DF) strategy. Results based on Monte-Carlo simulations indicate that the rateless coded hybrid scheme is able to significantly outperform two-hop cooperation, as well as the individual AF and DF strategies.\",\n \"Title: Outage capacity of the broadcast channel in the low power regime\\nYear: 2010\\n\\nAbstract: We consider outage capacity in the broadcast channel when the base-station has none or little channel knowledge. We find the minimum energy per bit needed to achieve a certain outage probability and the corresponding wideband slope.\",\n \"Title: Joint Slepian-Wolf/Dirty-paper coding\\nYear: 2013\\n\\nAbstract: We consider a joint Slepian-Wolf/Dirty-paper coding (SW-DPC) setup where a binary source needs to be transmitted over an additive white-Gaussian channel in the presence of interference known only at the encoder, as well as correlated side-information available only at the decoder. We propose a practical joint SW-DPC framework that uses a single low-density parity-check code coupled with trellis coded quantization to simultaneously provide error protection (in the face of noise and interference) and compression (in the face of correlated side-information available at the decoder). Simulation results indicate that the proposed joint SW-DPC scheme with finite-length codes outperforms a scheme with separate SW and DPC by 0.3 dB. In addition, we show that our joint SW-DPC code designed for one set of channel conditions is capable of achieving negligible bit-error rates for many other channel conditions as well. More specifically, it achieves successful decoding for a wide variety of channel conditions for which a separation-based scheme fails.\",\n \"Title: A distributed source coding technique for highly correlated images using turbo-codes\\nYear: 2002\\n\\nAbstract: According to the Slepian-Wolf theorem [1], the output of two correlated sources can be compressed to the same extent without loss, no matter if they communicate with each other or not, provided that the decompression takes place at a common decoder having both compressed outputs available. In this paper, as an application of the Slepian-Wolf theorem, an advanced distributed source coding scheme for correlated images is presented. Assuming that the correlated image is a noisy version of the original, the scheme involves modulo encoding of the pixel values and encoding (compression) of the resulting symbols with binary and nonbinary turbo-codes, so that rate savings are achieved practically without loss.\",\n \"Title: A Rateless Coded Protocol for Half-Duplex Wireless Relay Channels\\nYear: 2011\\n\\nAbstract: We propose a rateless coded protocol for a half-duplex wireless relay channel where all links experience independent quasi-static Rayleigh fading and the instantaneous channel realizations are unavailable at the transmitters. We assume that the network does not have a stringent delay constraint-thus the source and/or the relay continue transmitting until the destination acknowledges successful decoding. We identify rateless coded relaying as the natural choice, where each transmission from the source and/or the relay adds incremental redundancy to help the destination recover the original message. Our proposed protocol utilizes, in conjunction with rateless coding, a combination of the two popular relay cooperation schemes, namely decode-forward and compress-forward. Assuming very limited feedback from the destination, we derive the theoretical performance bounds specifically with binary phase-shift keying. We then implement the rateless coded relaying protocol using Raptor codes. The degree profiles for the Raptor codes are designed to maximize the average throughput-with the design formulated as a convex optimization problem. Using discretized density evolution for asymptotically large block lengths, the optimized codes lose approximately 5% in performance from the theoretical limit, whereas with practical finite block lengths, the performance loss is approximately 9%.\",\n \"Title: A New Sufficient Condition for Sum-Rate Tightness in Quadratic Gaussian Multiterminal Source Coding\\nYear: 2010\\n\\nAbstract: This paper considers the quadratic Gaussian multiterminal (MT) source coding problem and provides a new sufficient condition for the Berger–Tung (BT) sum-rate bound to be tight. The converse proof utilizes a set of virtual remote sources given which the observed sources are block independent with a maximum block size of 2. The given MT source coding problem is then related to a set of two-terminal problems with matrix-distortion constraints, for which a new lower bound on the sum-rate is given. By formulating a convex optimization problem over all distortion matrices, a sufficient condition is derived for the optimal BT scheme to satisfy the subgradient-based Karush–Kuhn–Tucker condition. The subset of the quadratic Gaussian MT problem satisfying our new sufficient condition subsumes all previously known tight cases, and our proof technique opens a new direction for more general partial solutions.\",\n \"Title: Matching Criterion between Source Statistics and Source Coding Rate\\nYear: 2015\\n\\nAbstract: Joint source-channel coding (JSCC) based on double protograph low-density parity-check (DP-LDPC) codes has been shown to be a good solution for wireless communications. However, the premature error-floor region of DP-LDPC codes usually does not meet the bit error rate (BER) requirements. In this paper, we provide a matching criterion between the source statistics and source coding rate using a novel protograph extrinsic information transfer (PEXIT) algorithm with a new decoding threshold. The resulting matching criterion helps predict the error-floor region performance and give directions for source coding rate designs.\",\n \"Title: On Maximum Linearly Achievable Degrees of Freedom Region of 2<formula formulatype=\\\"inline\\\"><tex Notation=\\\"TeX\\\">$\\\\,\\\\times\\\\,$</tex> </formula>2<formula formulatype=\\\"inline\\\"><tex Notation=\\\"TeX\\\">$\\\\,\\\\times\\\\,$</tex> </formula>2 Interference Network With Arbitrary Antenna Configurations\\nYear: 2015\\n\\nAbstract: AbstractWe obtain the exact maximum Degrees of Freedom (DoF) region achieved by linear transceivers without symbol extensions of the 2 × 2 × 2 multiple-input multiple-output (MIMO) interference network, which is comprised of two sources, two relays and two destinations, each with arbitrary number of antennas. We prove that the maximum achievable DoF region for the networks under some antenna configurations coincide with the cut-set bound of the networks, while there is only one DoF gap from the bound for the networks under other configurations, which can not be bridged by linear transceivers. The basic idea of the proof is to construct a two-tier transceiver, where the first tier decomposes the general networks to several basic networks with special configurations, and the second tier achieves the maximal DoF tuples for these basic networks. A mechanism for constructing the second tier transceiver is proposed, which is referred to as channel scaling assisted interference elimination. Combined with interference avoidance at sources and interference cancelation at destinations depending on the antenna configurations, interference-free transmission can be ensured.\",\n \"Title: Robust layered multiple description coding of scalable media data for multicast\\nYear: 2005\\n\\nAbstract: Layered multiple description codes allow robust transmission of scalable media data over packet erasure networks, while providing simple rate adaptation and bandwidth savings for shared bottleneck links. We show how to efficiently design layered multiple description codes for multicast and broadcast applications in memoryless packet erasure networks. Our approach offers a significantly better qual...\",\n \"Title: A fast depth map coding method based on optimized modes decision\\nYear: 2015\\n\\nAbstract: Multiview video plus depth (MVD) has been widely used recently as the representation of 3D scenes. Due to the tremendous data volume, transmission of MVD sequences becomes difficult especially under networks circumstance. Hence, an efficient 3D video coding scheme is required to compress the video data. In this paper, a fast depth map coding method based on optimized inter-frame modes decision in H.264/AVC is proposed to improve the coding efficiency of depth maps. In our study, depth maps are divided into edge, foreground and background parts. For each part, the distribution of inter-frame modes is measured among sequences and only the most frequently used modes are selected as the candidate modes. Based on the statistic results, different modes decision strategies are applied to those three parts during coding process. Experiments show that the proposed method saves up to 76% coding time with negligible PSNR loss and bit rate overhead.\",\n \"Title: A Real-Time Face Tracking System Based On A Single Ptz Camera\\nYear: 2015\\n\\nAbstract: Conventional online education platforms implement a combination of static and PTZ (Pan-Tilt-Zoom) cameras which are not only costly but also require operators and high computational power. In this paper, we establish a real-time face tracking system based on a single PTZ camera with automatic operation as a cost effective solution. The proposed system takes into account the camera movement and network delays in the tracking algorithm design while maintaining cost and flexibility in practical implementation.\",\n \"Title: An Interference Reduction Method Based On Reference Planes For Light-Coding Depth Cameras\\nYear: 2015\\n\\nAbstract: Recently, light-coding depth cameras, with their relatively good performance, have been widely used for depth image generation. To extend the field of view, multiple depth cameras usually have to be employed for scene representation and reconstruction. However, the interference among multiple light-coding depth cameras degrades the quality of depth images significantly. In this paper, we present an interference reduction method based on reference planes for light-coding depth cameras. We characterize the mathematical model of pattern interference on each reference plane, and derive a method to extract depth values with the assistance of the reference planes. Experimental results show that our proposed method effectively reduces the interference caused by multiple light-coding based cameras.\",\n \"Title: On the energy-delay tradeoff in lossy network communications\\nYear: 2015\\n\\nAbstract: This work investigates the energy-delay tradeoff in real-time network communication systems with ARQ, where energy is measured by power and energy per bit, respectively. We consider the lossy communication case with a finite buffer size, where each block is allowed to be retransmitted under a time constraint. We apply finite blocklength results of channel coding into our system. By adaptively optimizing the blocklength, coding rate, power allocation, and maximum number of retransmissions according to the queue state, we algorithmically achieve the optimal energy-delay tradeoff. We also lower and upper bound the optimal energy-delay function in order to study its asymptotic behavior as the delay and buffer size go to infinity, showing consistency with existing result. That is: the energy per bit approaches the minimum of -1.59 dB as the delay goes to infinity and power approaches zero. We observe that the power increases very rapidly when delay moves away from infinity, meaning that it is very hard to achieve the -1.59 dB limit in practice.\",\n \"Title: Sending Gaussian Multiterminal Sources Over The Gaussian Mac With Bandwidth Expansion\\nYear: 2015\\n\\nAbstract: In this work, we investigate the minimum power of transmitting Gaussian multiterminal sources over the Gaussian multiple access channel (MAC) with bandwidth expansion. Distributed encoders observe the individual components of the multiterminal sources and attempt to describe them to a central decoder. Instead of assuming the sources and the channel have matched bandwidth, we consider the scenario when the transmission is subject to a bandwidth constraint in terms of the number of channel uses per source sample. We study the minimum transmission power such that the decoder can reconstruct the individual sources and meet the mean squared error (MSE) constraints on them. For any given bandwidth and distortion constraints, we optimize uncoded transmission to obtain an upper bound on the minimum transmission power. A hybrid coding scheme is then proposed to obtain a tighter upper bound.\",\n \"Title: Distortion Minimization Via Adaptive Digital And Analog Transmission For Energy Harvesting-Based Wireless Sensor Networks\\nYear: 2015\\n\\nAbstract: This paper studies wireless sensor networks with energy harvesting in which a transmitter collects the observed source signals from the sensors and send to a fusion center using the energy harvested from an ambient environment. The main objective is to minimize the distortion between the source signal observed by the sensors and that recovered by the fusion center. We introduce a novel adaptive transmission approach in which the transmitter can use either analog or digital transmission according to the dynamics of the energy harvesting process. We formulate the optimization problem as a Markov decision process (MDP) and derive the optimal policy that can minimize the long-term discounted distortion for the fusion center. Numerical results show that our proposed approach can significantly improve the network performance under different situations.\",\n \"Title: Texture-free large-area depth recovery for planar surfaces\\nYear: 2015\\n\\nAbstract: This paper presents a texture-free depth enhancement method for large-area depth recovery. The proposed algorithm identifies a large-area depth missing region, and iteratively segments its contour by setting different initial pixels in each iteration. Coordinate transformation is used to analyze the distribution of each contour segment. By examining distributions of all contour segments, statistical histogram analysis is applied in our approach to select contour pixels. Then, selected pixels are projected into the world coordinate system, and multiple linear regression is utilized for surface function approximation. Missing depth values of a large-area depth missing region can be recovered with guidance of the approximated surface function. Quantitative and qualitative evaluations over state-of-the-art depth enhancement methods demonstrate the effectiveness and superiority of our method. Being texture-free, the proposed method has the flexibility of being merged into traditional depth enhancement methods.\",\n \"Title: Use of Non-Orthogonal Multiple Access in Dual-hop relaying.\\nYear: 2016\\n\\nAbstract: To improve the sum-rate (SR) of the dual-hop relay system, a novel two-stage power allocation scheme with non-orthogonal multiple access (NOMA) is proposed. In this scheme, after the reception of the superposition coded symbol with a power allocation from the source, the relay node forwards a new superposition coded symbol with another power allocation to the destination. By employing the maximum ratio combination (MRC), the destination jointly decodes the information symbols from the source and the relay. Assuming Rayleigh fading channels, closed-form solution of the ergodic SR at high signal-to-noise ratio (SNR) is derived and a practical power allocation is also designed for the proposed NOMA scheme. Through numerical results, it is shown that the performance of the proposed scheme is significantly improved compared with the existing work.\",\n \"Title: Performance Improvement of JSCC Scheme Through Redesigning Channel Code.\\nYear: 2016\\n\\nAbstract: For joint source channel coding (JSCC) scheme based on double protograph low-density parity-check (DP-LDPC) codes, due to joint iterative decoding between the source and channel decoders, it is found that the optimal channel code in separate system is not optimal in joint system. In this letter, a novel joint protograph extrinsic information transfer analysis is proposed for the DP-LDPC system over AWGN and redesigning scheme for channel code is put forward to enhance the performance of DP-LPDC system. Both the EXIT analysis and the simulated results show the performance improvement of proposed systems. This verifies the viewpoint that the channel code should be redesigned for JSCC scheme even if the optimal channel codes are selected over AWGN in separate systems.\",\n \"Title: The diversity of STF-coded MIMO-OFDM systems with a general correlation model.\\nYear: 2016\\n\\nAbstract: Owing to insufficient antenna spaces, mobile scenarios, and multipaths in practice, transmission correlations in space, time, and frequency domains are inevitable in wireless communications. This paper studies the effect of general spatial, temporal, and frequency/path correlations on the performance of space-time-frequency (STF)-coded multiple-input, multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems over frequency-selective block-fading channels. Specifically, we first derive an upper bound on the maximum achievable diversity by Hadamard and tensor products and analyze the effect of general spatial, temporal, and frequency/path correlations on it using rank properties of block matrices. We then address STF code designs and give two examples, one traditional STF code and another quasi-SF code, to show that our upper bound on the maximum diversity is achievable. The decoding complexity is considered in the MIMO system with arbitrary correlated fading channels using the traditional STF code. We also identify the newly developed statistical channel models for MIMO LTE and 802.11n as special cases of our STF-coded MIMO-OFDM system by showing that our theoretical diversity results match those simulated from these statistical channel models. Finally, we show that our general diversity result recovers various maximum diversity gains for different special correlation scenarios that have appeared in the literature.\",\n \"Title: Knowledge-Based Coding of Objects for Multisource Surveillance Video Data.\\nYear: 2016\\n\\nAbstract: Global object redundancy (GOR), as opposed to local spatial/temporal redundancies in a single video clip, is a new form of redundancy common in multisource surveillance video data (MSVD). GOR is induced by the repetition of foreground objects across multiple cameras, and becomes influential as the number of objects increases. Eliminating GOR considerably improves MSVD coding efficiency. In an effort to accomplish this, this study first proposes a knowledge-based representation of objects based on careful analysis of GOR composition. The representation contains a constant part and a variational part: the former is used to represent the common knowledge shared by an object across multiple cameras, while the latter is used to represent local variations on the object's surfaces. Based on the proposed representation, a knowledge-based coding (KBC) method is then proposed in which each foreground object is encoded with a hybrid prediction scheme, where the constant part of the object is generated via global prediction from a model library and the variational part is predicted via local reference frames with pose-based, short-term prediction. Experimental results showed that the KBC method saves more than 39% bits on average for encoding foreground objects in high-resolution video clips (compared to 16% for the entire videos). Applying the proposed coding method to surveillance videos in large spatial and temporal scale allows storage savings at the PB level.\",\n \"Title: A Novel Computer-Aided Surgical Simulation (CASS) System to Streamline Orthognathic Surgical Planning.\\nYear: 2016\\n\\nAbstract: Orthognathic surgery is a surgical procedure to correct jaw deformities. It requires extensive presurgical planning. We developed a novel computer-aided surgical simulation (CASS) system, the AnatomicAligner, for doctors planning the entire orthognathic surgical procedure in computer following our streamlined clinical protocol. The computerized plan can be transferred to the patient at the time of surgery using digitally designed surgical splints. The system includes six modules: image segmentation and three-dimensional (3D) model reconstruction; registration and reorientation of the models to neutral head posture (NHP) space, 3D cephalometric analysis, virtual osteotomy, surgical simulation, and surgical splint designing. The system has been validated using the 5 sets of patient’s datasets. The AnatomicAligner system will be soon available freely to the broader clinical and research communities.\",\n \"Title: Full-Duplex Machine-To-Machine Communication For Wireless-Powered Internet-Of-Things\\nYear: 2016\\n\\nAbstract: This paper considers machine-to-machine (M2M) communication for wireless-powered Internet-of-Things (IoT) based networking systems. Motivated by the observation that transmitting signals generally requires more energy than receiving signals for most IoT-based systems, we study a special wireless-powered M2M communication system in which the receiver can send its surplus energy to the transmitter. We propose a framework of wireless powered full-duplex M2M communication (WP-FD-M2M) in which the energy transfer from the receiver to the transmitter and the data transmission from the transmitter to the receiver take place at the same time over the same frequency. We establish a stochastic game-based model, referred to as the M2M game, to characterize the interaction between autonomous M2M transmitter and receiver. We prove that, if the transmitter and receiver can sequentially optimize their data transmission and energy transfer based on the Markov strategy, it is possible to achieve the maximum long-term performance for M2M communication without a centralized controller or coordination between the transmitter and receiver. Numerical results show that our proposed approach can significantly improve the performance for M2M communication under various situations.\",\n \"Title: Energy-Saving Predictive Resource Planning and Allocation.\\nYear: 2016\\n\\nAbstract: Predictive resource allocation is an emerging approach to improve the performance of mobile systems as human behavior is reported predictable by leveraging big data analytics. Yet what information can be predicted by big data, what information need to be predicted for wireless access optimization, how to translate the information, and how to exploit the synthetic knowledge for allocating radio res...\",\n \"Title: Optimal Caching and Scheduling for Cache-enabled D2D Communications.\\nYear: 2017\\n\\nAbstract: To maximize offloading gain of cache-enabled device-to-device (D2D) communications, content placement and delivery should be jointly designed. In this letter, we jointly optimize caching and scheduling policies to maximize successful offloading probability, defined as the probability that a user can obtain desired file in local cache or via D2D link with data rate larger than a given threshold. We obtain the optimal scheduling factor for a random scheduling policy that can control interference in a distributed manner, and a low complexity solution to compute caching distribution. We show that the offloading gain can be remarkably improved by the joint optimization.\",\n \"Title: Very Low-Resolution Face Recognition via Semi-Coupled Locality-Constrained Representation\\nYear: 2016\\n\\nAbstract: Recognition tasks in very low-resolution (VLR) images are more challenging than those in high-resolution (HR) due to lack of adequate discriminative information. Previous VLR and HR coupled learning scheme limits both the representation and discriminative ability of features. In this work, we propose a semi-coupled locality-constrained representation (SLR) approach to learn the discriminative representations and the mapping relationship between VLR and HR features simultaneously. Both VLR and HR local manifold geometries are coded during representation, while the learned mapping function improves the manifold consistency by transforming VLR features to HR ones. Finally, the resolutionrobust features are fed into a sparse representation based classifier (SRC) to predict the face labels. The proposed algorithm gives better performance than many state-of-the-art VLR recognition algorithms.\",\n \"Title: Two-Stage Power Allocation for Dual-Hop Relaying Systems With Non-Orthogonal Multiple Access.\\nYear: 2017\\n\\nAbstract: To improve the sum-rate (SR) and the outage probability of the dual-hop relay system, a novel two-stage power allocation scheme with non-orthogonal multiple access is proposed. In this scheme, after the reception of the superposition coded symbol with a power allocation from the source, the relay decodes-and-forwards a new superposition coded symbol with another power allocation to the destination. By employing a simple linear combination, the destination jointly decodes the information symbols from the received signals from the source and the relay. Assuming Rayleigh fading channels, the ergodic SR and the outage performance of the system are investigated. In addition, a suboptimal power allocation strategy with closed form of the power allocation factors is also designed, which is close to the optimal one. Through numerical results, it is shown that the performance of the proposed scheme is significantly improved compared with the existing works.\",\n \"Title: Robust Face Super-Resolution via Locality-Constrained Low-Rank Representation.\\nYear: 2017\\n\\nAbstract: Learning-based face super-resolution relies on obtaining accurate a priori knowledge from the training data. Representation-based approaches (e.g., sparse representation-based and neighbor embeddingbased schemes) decompose the input images using sophisticated regularization techniques. They give reasonably good reconstruction performance. However, in real application scenarios, the input images are often noisy, blurry, or suffer from other unknown degradations. Traditional face super-resolution techniques treat image noise at the pixel level without considering the underlying image structures. In order to rectify this shortcoming, we propose in this paper a unified framework for representation-based face super-resolution by introducing a locality-constrained low-rank representation (LLR) scheme to reveal the intrinsic structures of input images. The low-rank representation part of LLR clusters an input image into the most accurate subspace from a global dictionary of atoms, while the locality constraint enables recovery of local manifold structures from local patches. In addition, low-rank, sparsity, locality, accuracy, and robustness of the representation coefficients are exploited in LLR via regularization. Experiments on the FEI, CMU face database, and real surveillance scenario show that LLR outperforms the state-of-the-art face super-resolution algorithms (e.g., convolutional neural network-based deep learning) both objectively and subjectively.\",\n \"Title: Face Hallucination Using Deep Collaborative Representation For Local And Non-Local Patches\\nYear: 2017\\n\\nAbstract: Patch-based face hallucination algorithms utilize either local patches (e.g., position-patch approaches) or nonlocal patches (e.g., dictionary-learning approaches) to exploit self-similarity prior from training samples. Although they yield decent results, solo source patches limit their performance due to not fully taking self-similarity prior from both local and nonlocal ones. In order to overcome this shortcoming, we propose a novel and efficient deep collaborative representation (DCR) based approach, to exploit both local and nonlocal self-similarity patches, for boosting face hallucination performance. First we learn a feature-inducing dictionary pair to represent local and nonlocal self-similarity prior, then deep (multiple-layer) representation weights and corresponding support dictionaries are iteratively updated to exploit accurate prior from coarse to fine. Finally, the high resolution (HR) output are optimized layer by layer. Experimental results outperform some state-of-the-art (e.g. Convolutional Neural Network based deep learning approach) which verify the validity of the proposed approach.\",\n \"Title: Reliability-Oriented Decoding Strategy for LDPC Codes-Based D-JSCC System.\\nYear: 2017\\n\\nAbstract: In this letter, a reliability oriented decoding strategy (RODS) for low density parity check codes-based distributed joint source and channel coding system is proposed. During each local decoding iteration, the reliability of each variable node is evaluated based on the sign of received log-likelihood ratios (LLRs) and its oscillation situation. Then, by employing reliability-oriented updating operation, the negative influence of those inaccurate messages is suppressed. Moreover, extra operations are performed on a group of most unreliable source nodes so that more accurate posteriori LLRs can be obtained. During global iteration, offset operation is performed to reduce error propagation. The simulation results illustrate that the proposed RODS outperforms other decoding algorithms at the aspects of error correction performance and convergence speed, especially when the correlation between distributed sources is low.\",\n \"Title: Low-rank constrained collaborative representation for robust face recognition\\nYear: 2017\\n\\nAbstract: Recently, sparse representation based classifiers (SRC) and collaborative representation based classifiers (CRC) have been shown to give very good performance under controlled scenarios. However, in practical applications, face recognition often encounters variations in illumination, expression, noise and occlusion, which cause severe performance degradation (due to the outliers in testing). In this paper, we present a novel robust face recognition algorithm based on class-wise low-rank constrained collaborative representations. We impose a low-rank constraint on the representation coefficient matrix to discriminate against outliers. The resulting low-rank constrained collaborative representation based classifier (LCRC) jointly minimizes the class-wise reconstruction error and rank of coefficient matrix. Experiments show that LCRC outperforms popular classifiers such as SRC, CRC, SVM, PROCRC on the AR, CMU PIE and LFW databases.\",\n \"Title: Fault-tolerance based block-level bit allocation and adaptive RDO for depth video coding\\nYear: 2017\\n\\nAbstract: Depth videos affect the visual quality of virtual view greatly, while conventional encoders are not adapted to encode depth videos. To solve this problem, we propose, in the paper, a fault-tolerance based joint block-level bit allocation scheme for depth video coding. The scheme classifies depth blocks into two classes by the fault-tolerance, and constructs virtual view perceptual quality based rate-distortion (R-D) model for each class. Based on the model, a joint block-level bit allocation scheme is proposed to obtain the optimized quantization parameter (QP) to encode each class of blocks. Further, an adaptive RDO algorithm is designed to determine λ\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">MODE</sub>\\n, in order to achieve better visual quality of virtual views. Experimental results demonstrate that, compared with 3D-HEVC, the proposed method improves the visual quality of virtual views, especially at preserving details and boundaries of objects.\",\n \"Title: Design, development and clinical validation of computer-aided surgical simulation system for streamlined orthognathic surgical planning.\\nYear: 2017\\n\\nAbstract: There are many proven problems associated with traditional surgical planning methods for orthognathic surgery. To address these problems, we developed a computer-aided surgical simulation (CASS) system, the AnatomicAligner, to plan orthognathic surgery following our streamlined clinical protocol.\",\n \"Title: Hevc-Based Compression Of High Bit-Depth 3d Seismic Data\\nYear: 2017\\n\\nAbstract: In a previous work [1] we applied the idea of HEVC intra coding to compression of 32 b/p seismic images. Results are significantly better than those from a licensed commercial wavelet-based codec that is currently used at Shell for seismic image compression, which performs on par with JPEG-XR. Building upon [1], this paper exploits HEVC-based inter predictive coding for 3D 32 b/p seismic data. We propose a new model for the Lagrange multiplier in R-D optimization to accommodate 32 b/p bit-depth and extended quantization parameter range. We also focus on reducing the complexity of motion estimation to meet application needs. Experiments with our new codec show a 95% complexity reduction of encoding time at 10:1 compression ratio with only 1 dB loss on average PSNR. The compression performance and subjective quality of our codec received high evaluation marks from Shell geologists.\",\n \"Title: Face Hallucination Using Region-Based Deep Convolutional Networks\\nYear: 2017\\n\\nAbstract: Most deep learning based face hallucinations exploit random patch prior from training samples, then to learn the mapping functions between low-resolution (LR) and high-resolution (HR) images, and achieve satisfactory reconstruction performance. However, most of them do not take into account the prior information on facial structure, which is pivotal for face hallucination. Different from random patch prior based deep learning approaches, in this paper, we utilize facial structural prior and develop a simple yet powerful face hallucination, named region-based deep convolutional networks (RDCN). Firstly, we divide facial image into several regions of interest, then to train multiple parallel subnetworks of these regions for exacting better structure priors, finally HR output is reconstructed by stitching facial parts. Experiments on the FEI database demonstrate that the proposed region-based convolution networks outperform other state-of-the-art, including recently proposed deep learning based approaches, both in subjective and objective reconstruction qualities.\",\n \"Title: A Noncoverage Field Model for Improving the Rendering Quality of Virtual Views.\\nYear: 2018\\n\\nAbstract: Rendering quality optimization theory is one of the most basic and fascinating components of image-based rendering (IBR). The rendering quality of virtual views is related to the information in the source images. Capturing the image information depends on the geometric configuration of the camera (GCC) and, in particular, the positions and shooting directions of the cameras. Therefore, the rendering quality of virtual views can be improved by optimizing the GCC. This paper investigates the relationship between the GCC and the geometric configurations of the virtual view (GCVV). The influence of the GCC on the rendering quality is also analyzed. Based on the relationships among the GCC, GCVV, and rendering quality, a mathematical model of the noncoverage field (NCF) is proposed to quantify the rendering quality. The performance of the NCF is also analyzed using a set of GCVVs and GCCs. Furthermore, an optimization algorithm based on the NCF that simultaneously optimizes the position and direction of the GCC is presented. The proposed technique can be applied to obtain the optimal rendering quality of IBR for the linear case of camera positions and virtual views. Finally, experimental results are presented and compared with the theoretical results.\",\n \"Title: Exploiting Residual Resources to Support High Throughput with Resource Allocation.\\nYear: 2018\\n\\nAbstract: Residual radio resources are abundant in wireless networks due to dynamic traffic load, which can be exploited to support high throughput for serving non-real-time (NRT) traffic. In this paper, we investigate how to achieve this by resource allocation with predicted time-average rate, which can be obtained from predicted average residual bandwidth after serving real-time traffic and predicted average channel gains of NRT mobile users. We show the connection between the statistics of their prediction errors. We formulate an optimization problem to make a resource allocation plan within a prediction window for NRT users that randomly initiate requests, which aims to fully use residual resources with ensured quality of service (QoS). To show the benefit of knowing the contents to be requested and the request arrival time in advance, we consider two types of NRT services, video on demand and video on reservation. The optimal solution is obtained, and an online policy is developed that can transmit according to the plan after instantaneous channel gains are available. Simulation and numerical results validate our analysis and show a dramatic gain of the proposed method in supporting high arrival rate of NRT requests with given tolerance on QoS.\",\n \"Title: AWCR: Adaptive and Weighted Collaborative Representations for Face Super-Resolution with Context Residual-Learning.\\nYear: 2017\\n\\nAbstract: Owing to the ill-posed nature of the image super-resolution (SR) problem, learning-based approaches typically employ regularization terms in the representation. Current local-patch based face SR approaches weight representation coefficients to obtain adaptive and accurate priors. However, they ignore the fact that heteroskedasticity generally exists both in the observed data and representation coefficients. In this paper, we present a novel adaptive and weighted representation framework for face SR to further exploit adaptive and accurate prior information for different content inputs. Moreover, we enrich patch priors by sampling context patches, and learn the residual high-frequency components for better reconstruction performance. Experiments on the CAS-PEAL-R1 face database show that our proposed approach outperforms state-of-the-arts that include other deep learning based methods.\",\n \"Title: Robust and efficient face recognition via low-rank supported extreme learning machine.\\nYear: 2018\\n\\nAbstract: Recently, face recognition algorithms have made great progress in various real-world applications, e.g., authentication and criminal investigation. Deep-learning offers an end-to-end paradigm for vision recognition tasks and achieves good performance. However, designing and training the complex network architecture are time-consuming and labor-intensive. Moreover, under complex scenarios, illumination change, noise or occlusion in images degrade the performance of recognition algorithms. In order to ameliorate these issues, we propose an efficient three-layered low-rank supported extreme learning machine (LSELM) algorithm for face recognition which improves the recognition performance under complex scenarios with high efficiency. In the first layer, a given probe sample is clustered into certain training subspace as pre-clustering. In the second layer, with this subspace, a low-rank subspace of probe sample as robust feature which is insensitive to disguise, noise, variant expression or illumination will be recovered by low-rank decomposition. Furthermore, these low-rank discriminative features are coded to support training a forward neural network termed LSELM. Experimental results indicate that the proposed approach is on par with some deep-learning based face recognition algorithms on recognition performance but with less time complexity over some popular face datasets e.g., AR, Extend Yale-B, CMU PIE and LFW datasets.\",\n \"Title: Enhanced Discriminative Generative Adversarial Network for Face Super-Resolution.\\nYear: 2018\\n\\nAbstract: Recently, some generative adversarial network (GAN)-based super-resolution (SR) methods have progressed to the point where they can produce photo-realistic natural images by using a generator (G) and discriminator (D) adversarial scheme. However, vanilla GAN-based SR methods cannot achieve good reconstruction and perceptual fidelity on real-world facial images at the same time. Because of D loss, them are hard to converge stably, which may cause the model collapse. In this paper, we present an Enhanced Discriminative Generative Adversarial Network (EDGAN) for SR facial recognition to achieve better reconstruction and perceptual fidelities. First, we discover that a versatile D boosts the adversarial framework to a preferable Nash equilibrium. Then, we design the D via dense connections, which brings more stable adversarial loss. Furthermore, a novel perceptual loss function, by reusing the intermediate features of D, is used to eliminate the gradient vanishing problem of Gs. To our knowledge, this is the first framework to focus on improving the performance of the D. Quantitatively, experimental results show the advantages of EDGAN on two widely used facial image databases against the state-of-the-art methods with different terms. EDGAN performs sharper and realistic results on real-world facial images with large pose and illumination variations than its competitors.\",\n \"Title: SLR: Semi-Coupled Locality Constrained Representation for Very Low Resolution Face Recognition and Super Resolution.\\nYear: 2018\\n\\nAbstract: Although face recognition algorithms have been greatly successful recently, in real applications of very low-resolution (VLR) images, both super-resolution (SR) and recognition tasks are more challenging than those in high-resolution (HR) images. Given the rare discriminative information in VLR images, the one-to-many mapping relationship between HR and VLR images degrades the SR and recognition performances. In this paper, we propose a novel semi-coupled dictionary learning scheme to promote discriminative and representative abilities for face recognition and SR simultaneously by relaxing coupled dictionary learning. Specifically, we use semi-coupled locality-constrained representation to enhance the consistency between VLR and HR local manifold geometries, thereby overcoming the negative effects of one-to-many mapping. Given the learned task-oriented mapping function, we feed these discriminative features into a collaborative representation-based classifier to output their labels, and combine a locality-induced approach to hallucinate the HR images. Extensive experimental results demonstrate that the proposed approach outperforms a number of state-of-the-art face recognition and SR algorithms.\",\n \"Title: iLDPC coded RCM scheme with optimised interleaver.\\nYear: 2018\\n\\nAbstract: In this study, an irregular low-density parity-check (iLDPC) coded rate compatible modulation (iLDPC-RCM) is proposed. A particularly designed interleaver is inserted between LDPC and RCM such that a fast convergence and a low bit-error rate (BER) can be achieved. The combination of strong error correction capability of irregular LDPC code and the seamless adaptation of RCM enables the proposed sc...\",\n \"Title: Interference Coordination and Resource Allocation Planning With Predicted Average Channel Gains for HetNets.\\nYear: 2018\\n\\nAbstract: Future average channel gains are recently reported predictable within a minute-level horizon for a mobile user. Predictive resource allocation for non-realtime service with future average channel gains in a time window of one or more minutes long has been demonstrated effective in improving user experience and network throughput as well as reducing energy consumption. Nonetheless, existing studies for predictive resource allocation never consider inter-cell interference (ICI), which severely limits the user experience and network performance in densely-deployed cellular networks. This paper investigates predictive resource allocation in heterogeneous networks, where some base stations generate strong ICIs to some mobile users requesting non-realtime service. Optimizing the resource allocation in a predictive manner for interference networks is challenging, since how to allocate future resources depends on the future signal to interferenceplus-noise ratio, which in turn relies on the assigned resources. To deal with this difficulty, we introduce a predictive interference coordination scheme to divide all BSs and users into groups, where the BS-user pairs in each group can communicate simultaneously in a second-level frame. Then, we optimize a common resource allocation plan for all users in each group. The plan essentially determines which BSs in the group should be muted and the users should be associated with which active BS in each frame of the prediction window. By resorting to graph theory, we obtain the optimal solution and derive a low-complexity algorithm. Simulation results show that the proposed scheme outperforms existing relevant methods in terms of user satisfactory rate in heterogeneous networks with heavy traffic load.\",\n \"Title: Jointly Optimizing User Association and BS Muting for Cache-Enabled Networks With Network-Coded Multicast and Reconstructed Interference Cancelation.\\nYear: 2018\\n\\nAbstract: In this paper, we strive to improve the throughput of heterogeneous cellular networks by exploiting the pre-cached files at user end to manage interference. We consider a transmission scheme, where network-coded multicast is employed to help cancel multi-user interference, and reconstructed interference cancellation (RIC) is used to help eliminate inter-cell interference. Because RIC is opportunis...\",\n \"Title: Augmented Reality Sandpit Simulating Ant Colonies\\nYear: 2018\\n\\nAbstract: The way ants navigate their environment and forage for food is an intricate process. A common way ant species navigate is by using pheromone chemical trails leading to and from food sources. This paper summarizes an augmented reality sandpit project that aims to show the creation and evolution of these pheromone trails within a colony in an interactive way. A complex yet accessible simulation was built to allow users to move sand in a real sandpit while seeing virtually projected images on top of the sandpit change accordingly to showcase emergent ant colony behavior. A demo video of the project is available at https://www.youtube.com/watch?v=63Kx_xVEZkk.\",\n \"Title: Group Embedding for Face Hallucination.\\nYear: 2018\\n\\nAbstract: Face hallucination refers an application-specific super-resolution (SR) which predicts high-resolution images from one or multiple low-resolution inputs. Learning-based SR algorithms infer latent HR images by the guidance of coexisted priors from training samples. Various regularization methods have been successfully applied in face hallucination to ameliorate its ill-posed nature. But most of them only consider the local manifold geometry of a single patch which results in an unstable solution for SR reconstruction. In this paper, we propose a novel face hallucination algorithm to embed group patches for accurate prior representation and reconstruction. First, we select multiple recurrent self-similar patches to form a group embedding matrix. Then, a graph regularization term and another multiple-manifold regularization term are used to exploit accurate representation for SR performance. Our resulting ADMM algorithm gives a stable solution in an iterative manner. Furthermore, we use a two-step searching strategy for accelerated patch matching. Experimental results on the LFW database, FEI database, and some real-world images demonstrate the superiority of the proposed method when compared with state-of-the-art face hallucination results both on subjective and objective qualities.\",\n \"Title: Document Verification: A Cloud-Based Computing Pattern Recognition Approach to Chipless RFID.\\nYear: 2018\\n\\nAbstract: In this paper, we propose a novel means of verifying document originality using chipless RFID systems. The document sender prints a chipless RFID tag into the paper and does a frequency scanning in the 57-64 GHz spectrum of the document. The results of scattering parameters in individual step frequencies are stored in a cloud database, denoised and passed to pattern classifiers, such as support vector machines or ensemble networks. These supervised learners train themselves based on these data on the remote/cloud computer. The document receiver verifies this frequency fingerprint by using the same scanning method, sending the scattering parameters to the cloud server and getting the decoded data. Paper originality is verified if the decoded data are as expected. The advantages of our cloud chipless RFID processing deployments are cost reduction and increased security and scalability.\",\n \"Title: Separability and Compactness Network for Image Recognition and Superresolution.\\nYear: 2019\\n\\nAbstract: Convolutional neural networks (CNNs) have wide applications in pattern recognition and image processing. Despite recent advances, much remains to be done for CNNs to learn a better representation of image samples. Therefore, constant optimizations should be provided on CNNs. To achieve a good performance on classification, intuitively, samples' interclass separability, or intraclass compactness should be simultaneously maximized. Accordingly, in this paper, we propose a new network, named separability and compactness network (SCNet) to rectify this problem. SCNet minimizes the softmax loss and the distance between features of samples from the same class under a jointly supervised framework, resulting in simultaneous maximization of interclass separability and intraclass compactness of samples. Furthermore, considering the convenience and the efficiency of the cosine similarity in face recognition tasks, we incorporate it into SCNet's distance metric to enable sample features from the same class to line up in the same direction and those from different classes to have a large angle of separation. We apply SCNet to three different tasks: visual classification, face recognition, and image superresolution. Experiments on both public data sets and real-world satellite images validate the effectiveness of our SCNet.\",\n \"Title: Channel Symmetry In Slepian-Wolf Code Design Based On Ldpc Codes With Application To The Quadratic Gaussian Wyner-Ziv Problem\\nYear: 2004\\n\\nAbstract: We consider Slepian-Wolf code design (or source coding with side information) based on LDPC codes. We show that density evolution defined in conventional channel coding can be used in analyzing the Slepian-Wolf coding performance provided that certain symmetry condition, dubbed dual symmetry, is satisfied by the hypothetical channel between the source and the side information. Exploiting such an analysis, we design an efficient LDPC code based Slepian-Wolf coding scheme and apply it to the quadratic Gaussian Wyner-Ziv problems.\",\n \"Title: Accurate Depth Extraction Method for Multiple Light-Coding-Based Depth Cameras.\\nYear: 2017\\n\\nAbstract: Using multiple depth cameras can extend the field of view, which is beneficial to three-dimensional (3D) reconstruction. However, multiple active depth cameras would interfere with each other, which degrades the quality of depth images significantly. In this paper, we first present a depth extraction method based on sampling of the space at camera viewpoints to address the interference problem. Compared with the previous plane-sweeping method based on structured-light stereo and multiview stereo, depth images with less depth errors and better shape of objects are generated. Then, we analyze factors affecting depth accuracy for light-coding-based depth cameras and demonstrate the proposed depth extraction method also improves the accuracy of depth images by utilizing multiple projected patterns. Based on the analysis, subpixel-based matching (SPM) is finally applied to further improve the depth accuracy obtained by the depth extraction method. In the image matching process of our method, nearest neighbor interpolation is utilized to each projector's image plane to increase their resolution, which leads to the improved depth accuracy at subpixel level and avoids the drawbacks of changing parameters of light-coding-based depth cameras. Experimental results under simulated and real-world examples validate our analysis and show that the proposed method not only mitigates the impacts of interference effectively but also further improves the accuracy of depth images by using SPM.\",\n \"Title: Deep Reinforcement Learning of Volume-Guided Progressive View Inpainting for 3D Point Scene Completion From a Single Depth Image\\nYear: 2019\\n\\nAbstract: We present a deep reinforcement learning method of progressive view inpainting for 3D point scene completion under volume guidance, achieving high-quality scene reconstruction from only a single depth image with severe occlusion. Our approach is end-to-end, consisting of three modules: 3D scene volume reconstruction, 2D depth map inpainting, and multi-view selection for completion. Given a single depth image, our method first goes through the 3D volume branch to obtain a volumetric scene reconstruction as a guide to the next view inpainting step, which attempts to make up the missing information; the third step involves projecting the volume under the same view of the input, concatenating them to complete the current view depth, and integrating all depth into the point cloud. Since the occluded areas are unavailable, we resort to a deep Q-Network to glance around and pick the next best view for large hole completion progressively until a scene is adequately reconstructed while guaranteeing validity. All steps are learned jointly to achieve robust and consistent results. We perform qualitative and quantitative evaluations with extensive experiments on the SUNCG data, obtaining better results than the state of the art.\",\n \"Title: Interference Range-Reduced Cooperative Multiple Access with Optimal Relay Selection for Large Scale Wireless Networks.\\nYear: 2019\\n\\nAbstract: Cooperative communication improves the link throughput of wireless networks through spatial diversity. However, it reduces the frequency reuse of the entire network due to the enlarged link interference range introduced by each helper. In this paper, we propose a cooperative medium access control (MAC) protocol with optimal relay selection (ORS-CMAC) for multihop, multirate large scale networks, which can reduce the interference range and improve the network throughput. Then, we investigate the performance gain achieved by these two competitive factors, i.e., the spatial frequency reuse gain and spatial diversity gain, in large scale wireless networks. The expressions of maximum network throughput for direct transmissions and cooperative transmissions in the whole network are derived as a function of the number of concurrent transmission links, data packet length, and average packet transmission time. Simulation results validate the effectiveness of the theoretical results. The theoretical and simulation results show that the helper can reduce the spatial frequency reuse slightly, and spatial diversity gain can compensate for the decrease of the spatial frequency reuse, thereby improving the network throughput from the viewpoint of the whole network.\",\n \"Title: Parallel Region-Based Deep Residual Networks for Face Hallucination.\\nYear: 2019\\n\\nAbstract: Face hallucination is a super-resolution algorithm specially designed to improve the resolution and quality of low-resolution (LR) input face images. Although a deep neural network offers an end-to-end mapping from LR to high-resolution (HR) images, most of the deep learning-based face hallucinations neglect the structure prior for face images. To utilize the highly structured facial prior, a parallel region-based deep residual network (PRDRN) was developed to predict the missing detailed information for accurate image reconstruction. Initially, the image is divided into multiple regions with the symmetry of face structures. Then, the sub-networks corresponding to multiple regions are trained in parallel. Finally, all reconstructed regions are combined to form the HR image. The experimental results on FEI, CASIA-Webface and CMU-MIT public face databases show that the proposed network outperforms other state-of-the-art approaches.\",\n \"Title: An Improved Stereo Matching Algorithm For Vehicle Speed Measurement System Based On Spatial And Temporal Image Fusion\\nYear: 2021\\n\\nAbstract: This paper proposes an improved stereo matching algorithm for vehicle speed measurement system based on spatial and temporal image fusion (STIF). Firstly, the matching point pairs in the license plate area with obviously abnormal distance to the camera are roughly removed according to the characteristic of license plate specification. Secondly, more mismatching point pairs are finely removed according to local neighborhood consistency constraint (LNCC). Thirdly, the optimum speed measurement point pairs are selected for successive stereo frame pairs by STIF of binocular stereo video, so that the 3D points corresponding to the matching point pairs for speed measurement in the successive stereo frame pairs are in the same position on the real vehicle, which can significantly improve the vehicle speed measurement accuracy. LNCC and STIF can be used not only for license plate, but also for vehicle logo, light, mirror etc. Experimental results demonstrate that the vehicle speed measurement system with the proposed LNCC+STIF stereo matching algorithm can significantly outperform the state-of-the-art system in accuracy.\",\n \"Title: Robust Vehicle Speed Measurement Based On Feature Information Fusion For Vehicle Multi-Characteristic Detection\\nYear: 2021\\n\\nAbstract: A robust vehicle speed measurement system based on feature information fusion for vehicle multi-characteristic detection is proposed in this paper. A vehicle multi-characteristic dataset is constructed. With this dataset, seven CNN-based modern object detection algorithms are trained for vehicle multi-characteristic detection. The FPN-based YOLOv4 is selected as the best vehicle multi-characteristic detection algorithm, which applies feature information fusion of different scales with both rich high-level semantic information and detailed low-level location information. The YOLOv4 algorithm is improved by combing with the attention mechanism, in which the residual module in YOLOv4 is replaced by the ECA channel attention module with cross channel interaction. An improved ECA-YOLOv4 object detection algorithm based on both feature information fusion and cross channel interaction is proposed, which improves the performance of YOLOv4 for vehicle multi-characteristic detection and reduces the model parameter size and FLOPs as well. A multi-characteristic fused speed measurement system based on license plate, logo, and light is designed accordingly. The system performance is verified by experiments. The experimental results show that the speed measurement error rate of the proposed system meets the requirement of the China national standard GB/T 21555-2007 in which the speed measurement error rate should be less than 6%. The proposed system can efficiently enhance the vehicle speed measurement accuracy and effectively improve the vehicle speed measurement robustness.\",\n \"Title: Trajectory is not Enough: Hidden Following Detection\\nYear: 2021\\n\\nAbstract: ABSTRACTIn outdoor crimes such as robbery and kidnapping, suspects generally secretly follow their victims in public places and then look for opportunities to commit crimes. Video anomaly detection (VAD) has achieved fruitful results through deep neural networks (DNN). However, as an abnormal behavior without obvious abnormal physical features, hidden following is highly similar to ordinary walking and accompanying behaviors, so it is difficult to effectively detect hidden dangerous followers using video anomaly detection methods or traditional trajectory analysis methods. We propose \\\"hidden follower'' detection (HFD) task and a HFD model based on gaze pattern extraction. It extracts gaze pattern features of pedestrians from gaze-interval-series and introduces a time series classification model to classify pedestrians with or without hidden following purposes. Based on this model, we propose a hidden follower detection framework (HFDF) to detect hidden followers from normal pedestrians, which utilizes the trajectories and gaze patterns extracted from videos. To cope with the lack of test data, we construct a dataset of 1200 pedestrians from the crowd simulation model to simulate scenes including hidden followers, and we also collected a surveillance video dataset including the hidden following behaviors. The experiments conducted on these two datasets show that HFDF can consistently outperform the state-of-the-art method by a notable margin in the HFD task on the commonly-used F1 benchmark.\",\n \"Title: Rethinking Lightweight: Multiple Angle Strategy for Efficient Video Action Recognition\\nYear: 2022\\n\\nAbstract: Video action recognition task involves modeling spatiotemporal information, and efficiency is critical to capture spatiotemporal dependencies in the video. Most existing models rely on optical flow information to capture the dynamic visual tempos between consecutive video frames. Although impressive performance can be achieved by combining optical flow with RGB, the time-consuming nature of optical flow computation cannot be ignored. Moreover, 3D CNN has successfully modeled spatiotemporal information, yet the enormous computational volume is unsuitable for real-time action recognition. In this letter, we propose a novel lightweight video feature extraction strategy that achieves better recognition performance with lower FLOPs. In particular, we perform convolution on the video cube from three orthogonal angles to learn its appearance and motion features. Compared with the computational volume of 3D CNN, our proposed method is more economical and thus meets the lightweight requirements. Extensive experimental results on public Something Something-V1&V2 and Diving48 datasets show our approach achieves the state-of-the-art performance.\",\n \"Title: Real and Pseudo Pedestrian Detection Method with CA-YOLOv5s Based on Stereo Image Fusion\\nYear: 2022\\n\\nAbstract: With the development of convolutional neural networks, the effect of pedestrian detection has been greatly improved by deep learning models. However, the presence of pseudo pedestrians will lead to accuracy reduction in pedestrian detection. To solve the problem that the existing pedestrian detection algorithms cannot distinguish pseudo pedestrians from real pedestrians, a real and pseudo pedestrian detection method with CA-YOLOv5s based on stereo image fusion is proposed in this paper. Firstly, the two-view images of the pedestrian are captured by a binocular stereo camera. Then, a proposed CA-YOLOv5s pedestrian detection algorithm is used for the left-view and right-view images, respectively, to detect the respective pedestrian regions. Afterwards, the detected left-view and right-view pedestrian regions are matched to obtain the feature point set, and the 3D spatial coordinates of the feature point set are calculated with Zhengyou Zhang's calibration method. Finally, the RANSAC plane-fitting algorithm is adopted to extract the 3D features of the feature point set, and the real and pseudo pedestrian detection is achieved by the trained SVM. The proposed real and pseudo pedestrian detection method with CA-YOLOv5s based on stereo image fusion effectively solves the pseudo pedestrian detection problem and efficiently improves the accuracy. Experimental results also show that for the dataset with real and pseudo pedestrians, the proposed method significantly outperforms other existing pedestrian detection algorithms in terms of accuracy and precision.\",\n \"Title: Spatiotemporal two-stream LSTM network for unsupervised video summarization\\nYear: 2022\\n\\nAbstract: Within user-created videos, the constantly changing content among neighboring images brings more challenge for the prior video summarization methods. Assuming the images' critical features are refined, one can obtain promising accuracy of keyframes' selection which is key in video summarization. In our work, we innovatively proposed a Spatiotemporal two-stream LSTM network-based (ST-LSTM) model to enhance the images' critical features with the combination of spatial saliency and temporal semantic dependencies which is referred to as the two-stream method. Motivated by the fact that sizable and moving objects attract more visual attention, we newly design a Saliency-area-based attention network to filter irrelative non-attractive information. We use the latest attention-based Bi-LSTM network to extract the temporal dependency on the semantic features. Furthermore, a multi-feature-based reward function is presented to reinforce the ST-LSTM model by integrating diversity, representativeness, and storyness. Last, the Deep Deterministic Policy Gradient (DDPG) algorithm is adopted to do the unsupervised training for the proposed method. Extensive experiments on the public datasets demonstrate that our method outperforms the state-of-the-art.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":200,"string":"200"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":265,"string":"265"}}},{"rowIdx":266,"cells":{"question_id":{"kind":"string","value":"Laurence B Milstein"},"question":{"kind":"string","value":"Generate an abstract for the title \"Disruptive Attacks on Video Tactical Cognitive Radio Downlinks.\" using the following items: 1. video transmission \n2. cognitive radio \n3. hostile environment \n4. disruptive attacks \n5. worst-case optimal energy allocation"},"answer":{"kind":"string","value":"We consider video transmission over a mobile cognitive radio (CR) system operating in a hostile environment where an intelligent adversary tries to disrupt communications. We investigate the optimal strategy for spoofing, desynchronizing, and jamming a cluster-based CR network with a Gaussian noise signal over a slow Rayleigh fading channel. The adversary can limit access for secondary users (SUs) by either transmitting a spoofing signal in the sensing interval, or a desynchronizing signal in the code acquisition interval. By jamming the network during the transmission interval, the adversary can reduce the rate of successful transmission. We show how the adversary can optimally allocate its energy across subcarriers during sensing, code acquisition, and transmission intervals. We determine a worst-case optimal energy allocation for spoofing, desynchronizing, and jamming, which gives an upper bound to the received video distortion of SUs. We also propose cross-layer resource allocation algorithms and evaluate their performance under disruptive attacks."},"correct_answer":{"kind":"string","value":"We consider video transmission over a mobile cognitive radio (CR) system operating in a hostile environment where an intelligent adversary tries to disrupt communications. We investigate the optimal strategy for spoofing, desynchronizing, and jamming a cluster-based CR network with a Gaussian noise signal over a slow Rayleigh fading channel. The adversary can limit access for secondary users (SUs) by either transmitting a spoofing signal in the sensing interval, or a desynchronizing signal in the code acquisition interval. By jamming the network during the transmission interval, the adversary can reduce the rate of successful transmission. We show how the adversary can optimally allocate its energy across subcarriers during sensing, code acquisition, and transmission intervals. We determine a worst-case optimal energy allocation for spoofing, desynchronizing, and jamming, which gives an upper bound to the received video distortion of SUs. We also propose cross-layer resource allocation algorithms and evaluate their performance under disruptive attacks."},"documents":{"kind":"list like","value":["Title: Performance Analysis Of Generalized Selection Combining Of M-Ary Ncfsk Signals In Rayleigh Fading Channels\nYear: 2003\n\nAbstract: In this paper, we propose and analyze the bit error performance of a generalized selection combining (GSC) receiver for M-ary noncoherent frequency shift keying (NCFSK) signals on i.i.d. Rayleigh fading channels with L antennas at the receiver. For each of the M hypotheses, the receiver combines the K largest outputs among the L available square-law detector outputs before proceeding to the bit detection process. We derive a closed-form expression for the bit error probability of the proposed (K, L) GSC receiver, and present numerical results to illustrate the bit error performance of this receiver for different values of M, K, and L. We also show that our generalized (K, L) GSC scheme and analysis encompass the previously reported schemes/analyses by Chyi et al and Hahn as special cases for K = 1 and K = L, respectively.","Title: Optimal allocation of bandwidth for source coding, channel coding, and spreading in CDMA systems\nYear: 2004\n\nAbstract: This paper investigates the tradeoffs between source coding, channel coding, and spreading in code-division multiple-access systems, operating under a fixed total bandwidth constraint. We consider two systems, each consisting of a uniform source with a uniform quantizer, a channel coder, an interleaver, and a direct-sequence spreading module. System A is quadrature phase-shift keyed modulated and ...","Title: Effects of imperfections on the performance of OFDM systems\nYear: 2009\n\nAbstract: Most OFDM analyses assume idealized conditions when it comes to the waveform at the receiver in terms of time and frequency synchronization. In addition, often a cyclic prefix (CP) longer than the channel delay spread is assumed, and thus the impact of the possible inter-symbol interference (ISI) from adjacent OFDM symbols is not a consideration. This work provides a consolidated framework for study and analysis of OFDM systems with imperfections. The imperfections include time and frequency synchronization errors, and channel delay spread beyond the CP duration. Transmit as well as receive filtering operations are explicitly modeled, and different receiver detection criteria are considered. The use of an OFDM waveform for UWB applications is known to be a promising choice to simplify the receiver design and to maximize the bandwidth scalability, as well as the adaptation to various spectrum allocations. We present bit error rate (BER) sensitivity analysis to key system parameters for OFDM-based UWB applications. From these sensitivity analyses, we see graceful performance degradation with decreasing CP length and increasing residual frequency error. The performance degradation can be much more critical for timing synchronization errors.","Title: Motion-Compensated Scalable Video Transmission over MIMO Wireless Channels under Imperfect Channel Estimation\nYear: 2009\n\nAbstract: We study motion compensated fine granular scalable (MC-FGS) video transmission over multi-input multi-output (MIMO) wireless channels, where leaky and partial prediction schemes are applied in the enhancement layer of MC-FGS to exploit the tradeoff between error propagation and coding efficiency. For reliable transmission, we propose unequal error protection (UEP) by considering a tradeoff between reliability and data rates, which are controlled by forward error correction (FEC) and MIMO mode selection to minimize the average distortion. In a high Doppler environment where it is hard to get an accurate channel estimate, we investigate the performance of the proposed MC-FGS video transmission scheme with joint control of the leaky and partial prediction parameters and the UEP.","Title: Unequal error protection based on slice visibility for transmission of compressed video over OFDM channels\nYear: 2011\n\nAbstract: We address channel code rate optimization for transmission of non-scalable coded video sequences over orthogonal frequency division multiplexing networks. A slice loss visibility (SLV) model is used to evaluate the visual importance of each H.264 slice. Based on both the SLV model and the frequency diversity order available from the channel, we propose a cross-layer technique to allocate video slices within a 2-D time-frequency resource block, and optimize the unequal channel code rate profile, in order to better protect more visually important slices. The proposed algorithm outperforms baseline ones which do not take into account the SLV.","Title: Hybrid pulse position modulation/ultrashort light pulse code-division multiple-access systems .I. Fundamental analysis.\nYear: 2002\n\nAbstract: We propose a hybrid pulse position modulation/ultrashort light pulse code-division multiple-access (PPM/ULP-CDMA) system for ultrafast optical communications. The proposed system employs spectral CDMA encoding/decoding and PPM with very short pulse separation. The statistical properties of the encoded ULP are investigated with a general pulse model, and the performance of the proposed PPM/ULP-CDMA...","Title: Generalized unequal error protection LT codes for progressive data transmission.\nYear: 2012\n\nAbstract: The original design of standard digital fountain codes assumes that the coded information symbols are equally important. In many applications, some source symbols are more important than others, and they must be recovered prior to the rest. Unequal Error Protection (UEP) designs are attractive solutions for such source transmissions. In this study, we introduce a more generalized design for the first universal fountain code design, LT codes, that makes it particularly suited for progressive bit stream transmissions. We apply the generalized LT codes to a progressive source and show that it has better UEP properties than other published results in the literature. For example, using the proposed generalization, we obtained up to 1.7dB PSNR gain in a progressive image transmission scenario over the two major UEP fountain code designs.","Title: Power Control on the Forward Link in Cellular CDMA\nYear: 1994\n\nAbstract: In this paper, a CDMA cellular system is considered. An analysis of the performance is presented for the base-to-mobile link, along with a method to optimize the power control law. The performance of the system is evaluated in terms of both probability of error and system utilization (i.e., the number of admitted users per cell divided by the spreading factor). A comparison with some results which recently have appeared in the literature is also presented.","Title: An RF Receiver Detection Technique for Cognitive Radio Coexistence\nYear: 2010\n\nAbstract: A receiver detection technique is proposed by measuring the low-level leakage signal from a nearby receiver local oscillator. The probabilities of false alarm and missed detection are derived to quantify the detection performance. The technique provides higher sensitivity than a radiometer and is robust to estimation error even if the power spectral density of the ambient noise is unknown.","Title: The performance of a space-time spreading CDMA system with channel estimation errors.\nYear: 2002\n\nAbstract: Transmit diversity has been studied recently as an effective technique to provide high-performance wireless transmission. Space-time spreading is a transmit diversity scheme that achieves full spatial diversity while maintaining high spectral efficiency. This paper analyzes how channel estimation errors in diversity combining affects the uplink of a space-time spreading CDMA system with two transmit and two receive antennas. Pilot and data from K asynchronous users are transmitted through a Rayleigh multipath fading channel. The channel estimates are obtained at the outputs of correlators, and are used in the RAKE combiner. As a system becomes more wideband, more multipaths are resolved, and the energy in each path is reduced. This reduction in signal strength causes Increased estimation error and impacts the system performance. This paper studies the tradeoff between diversity and estimation errors.","Title: Performance of a wireless access protocol on correlated Rayleigh-fading channels with capture\nYear: 1998\n\nAbstract: The throughput performance of a wireless media access protocol taking into account the effect of correlated channel fading, capture, and propagation delay is analyzed. For efficient access on the uplink (mobile-to-base-station link), the protocol makes use of the uplink channel status information which is conveyed to the mobiles through a busy/idle flag broadcast on the downlink (base-station-to-m...","Title: The Impact of Nonlinear Amplification on Multi-Code CDMA Systems\nYear: 2000\n\nAbstract: This paper investigates the behavior of multi-code DS/CDMA systems in the presence of nonlinear distortions caused by high pourer amplifiers. A technique that uses a small number of parallel transmitted sequences is proposed for combating the nonlinearity. This technique can be modified to have a constant envelope for achieving further performance improvement. It is seen from performance comparisons that the proposed scheme is very effective for combating the nonlinearity.","Title: Analysis of hybrid, coherent FDMA/CDMA systems in Ricean multipath fading\nYear: 1997\n\nAbstract: This paper extends the analysis presented by Eng and Milstein (see IEEE J. Select. Areas Commun., vol.12, no.5, p.938-951, 1994) of a hybrid frequency division multiple access/code-division multiple-access [FDMA/CDMA (F/CDMA)] system in a Rayleigh fading environment to include the presence of a direct-path component (i.e., Ricean fading). The results show that a "wideband" CDMA system out performs...","Title: Video coding with fixed-length packetization for a tandem channel.\nYear: 2006\n\nAbstract: A robust scheme is presented for the efficient transmission of packet video over a tandem wireless Internet channel. This channel is assumed to have bit errors (due to noise and fading on the wireless portion of the channel) and packet erasures (due to congestion on the wired portion). First, we propose an algorithm to optimally switch between intracoding and intercoding for a video coder that operates on a packet-switched network with fixed-length packets. Different re-synchronization schemes are considered and compared. This optimal mode selection algorithm is integrated with an efficient channel encoder, a cyclic redundancy check outer coder concatenated with an inner rate-compatible punctured convolutional coder. The system performance is both analyzed and simulated. Last, the framework is extended to operate on a time-varying wireless Internet channel with feedback information from the receiver. Both instantaneous feedback and delayed feedback are evaluated, and an improved method of refined distortion estimation for encoding is presented and simulated for the case of delayed feedback.","Title: Exploiting multiuser diversity for fair scheduling in MIMO downlink networks with imperfect channel state information\nYear: 2009\n\nAbstract: In this paper, we consider a time-slotted MIMO point-to-multipoint network, which, for example, could represent either a cellular downlink, or a cluster in a wireless mesh network. The transmitter sends an independent data stream from each transmit antenna to communicate simultaneously to a subset of the receivers in each slot. The transmitter sends training symbols at the beginning of each slot so that each receiver can estimate the channel and determine the data rate it could potentially receive from each transmit antenna after configuring its antenna weights appropriately. For this purpose, we develop a maximum-likelihood estimator of the signal to interference plus noise ratio (SINR) from the received training symbols. The transmitter decides which receivers to serve in each slot to maximize the minimum normalized average data rate realized by each receiver. This scheduling decision is made based on estimated SINR information fed back by receivers. Through some numerical examples, we discuss some general issues with regard to exploitation of multi-user diversity in the context of imperfect channel state information. For example, the scheduler introduces a bias for positive SINR estimation errors, which is important to take into account when the receivers declare a potential data rate in each slot.","Title: Parallel acquisition in mobile DS-CDMA systems\nYear: 1997\n\nAbstract: This paper presents the performance of a direct sequence spread spectrum acquisition scheme in a mobile terrestrial communications system. The effects of fading, multipath, power control, shadowing, multiple access interference, out-of-cell interference, vehicle speed, voice activity, and sectorization are examined. The acquisition scheme uses noncoherent detection and a parallel search strategy. The analysis is done for the reverse link of a mobile code-division multiple-access (CDMA) system. The purpose of this paper is to derive the acquisition performance of a mobile communications system under practical assumptions, and give realistic capacity estimates based on acquisition performance criteria","Title: Error Rate of a Multicarrier CDMA System with Imperfect Channel Estimates\nYear: 2000\n\nAbstract: Bit error rate is evaluated for a multicarrier CDMA system with channel estimation errors. We consider a multicarrier CDMA system with pilot and data channels. The signal experiences independent flat Rayleigh fading on each subcarrier. Simple integrators produce the channel estimates which are used to maximal-ratio-combine the data from all the subcarriers, Keeping the total transmitted energy fixed, as the number of subcarriers increases, the weaker signal in each subcarrier makes channel estimation more difficult and results in larger errors in the combiner weights. We quantify how errors in channel estimation affect a multicarrier CDMA system as the system becomes more wideband. We will show that there is a tradeoff between diversity order and SNR available for channel estimation.","Title: Average SNR of a generalized diversity selection combining scheme\nYear: 1999\n\nAbstract: The average signal-to-noise ratio (SNR) of a gen- eralized selection combining scheme, in which the diversity branches ( , where is the total number of diversity branches available) with the largest instantaneous SNR's are selected and coherently combined, is derived. A Rayleigh fading channel is assumed, and a simple closed-form expression for the SNR is found which is upper bounded by the average SNR of maximal ratio combining, and lower bounded by average SNR of conventional selection combining. IVERSITY combining has been considered as an ef- ficient way to combat multipath fading because the combined signal-to-noise ratio (SNR) is increased compared with the SNR of each diversity branch. The optimum combiner is the maximal ratio combiner (MRC) whose SNR is the sum of the SNR's of each individual diversity branch. The conventional selection combiner (CSC) selects the signal from that diversity branch with the largest instantaneous SNR. In this paper, we study a generalized selection scheme. Instead of selecting only the largest (in instantaneous SNR) diversity signal as in CSC, we choose the largest signals from total diversity branches and then coherently combine them. The average SNR of this GSC is derived and a simple closed-form expression is found, which is upper bounded by the average SNR of MRC and lower bounded by the average SNR of CSC, as expected.","Title: Open-loop power control performance in DS-CDMA networks with frequency selective fading and non-stationary base stations\nYear: 1998\n\nAbstract: In this paper, we study the performance of a simple and easy-to-implement distributed power control strategy applicable to direct sequence code division multiple access (DS-CDMA) networks. The scheme makes use of the received power measurements made on the forward link at individual mobile units to control the transmit powers on their reverse links. The algorithm, which effectively compensates for the slowly varying distance and shadow losses (due to their high correlation on both forward and reverse links), attempts to minimize the effect of fast multipath fading by averaging it out. We adopt a quasi-analytic approach to estimate the reverse link capacity performance of an open-loop power control scheme in both a single cell and a multi-cell environment, and we do this for both a fixed base station and a moving base station scenario. Non-stationary base stations are typical in tactical and emergency communications scenarios where the base stations could be mounted on moving platforms (e.g., tanks, jeeps, unmanned airborne vehicles). We estimate the capacity degradation, when base stations move relative to other cells, as a function of the amount of cell overlap and the standard deviation of the power control error. We also provide a comparison of the performance of the open-loop power control strategy with that of a closed-loop power control strategy.","Title: Performance of Multiple Antenna DS-CDMA UWB System With Noisy Channel Estimates and Narrow-Band Interference\nYear: 2007\n\nAbstract: In this work, the performance of a DS-CDMA ultra-wideband (UWB) system with multiple antennas at the receiver, in the presence of multiple users and narrow-band interference (NBI), is evaluated. A spatio-temporal UWB receiver is proposed which first forms an estimate of the channel in the presence of multi-access interference and NBI, and then uses this estimate to optimally combine the multipath ...","Title: First-Order Markov Models For Packet Transmission On Rayleigh Fading Channels With Dpsk/Ncfsk Modulation\nYear: 2006\n\nAbstract: In this paper, we develop first-order Markov mod- els that characterize the packet error processes on Rayleigh fading channels considering binary DPSK/NCFSK modulation. Such models available in the literature so far consider only the fading process ignoring the underlying modulation used. Our contribution in this paper is that we consider first-order Markov models for binary DPSK/NCFSK modulation. To derive the Markov model parameters, we first derive expressions for the second-order statistics of the channel error process (specifically, the auto-correlation function of the bit error process as well as the packet error process), and obtain the Markov model parameters, in closed-form, as a function of normalized Doppler bandwidth, average received SNR and packet length. We also verify the accuracy of the proposed Markov model by deriving closed-form expressions for the mutual information of the channel error process.","Title: Performance analysis of coded communication systems on Nakagami fading channels with selection combining diversity\nYear: 2004\n\nAbstract: In this paper, we develop analytical tools for the performance analysis of coded, coherent communication systems on independent and identically distributed Nakagami-m fading channels with selection combining (SC) diversity. First, we derive an exact expression for the moment generation function (MGF) of the signal-to-noise ratio (SNR) of a code symbol at the output of the selection combiner. Next,...","Title: The performance of a direct-sequence spread-spectrum acquisition system using a linear prediction filter for narrowband interference suppression\nYear: 1996\n\nAbstract: The coarse acquisition performance of a direct sequence spread-spectrum receiver is analyzed when a linear prediction filter is used for narrowband interference suppression. We show that once an appropriate matching strategy is identified, the linear prediction filter can provide favorable performance when narrowband interference is present over a considerable range of both interference power and bandwidth. In addition, the presence of the filter dramatically improves the performance over the case where there is no filter, except when the interference bandwidth and the power are both small (i.e., when the processing gain provides sufficient interference immunity without the filter). If long spreading sequences are used with moderately sized observation windows, the acquisition performance can be severely degraded when a parallel acquisition scheme is used due to the linear predication filter. We show, however, that a slower serial receiver will provide reliable performance.","Title: Multicode Mimo For High Data Rate Mobile Ad-Hoc Networks\nYear: 2006\n\nAbstract: In a mobile ad-hoc network scenario, where communication nodes are mounted on moving platforms (like jeeps, trucks, tanks, etc.), use of V-BLAST requires that the number of receive antennas in a given node must be greater than or equal to the sum of the number of transmit antennas of all its neighbor nodes. This limits the achievable spatial multiplexing gain (data rate) for a given node. In such a scenario, we propose to achieve high data rates per node through multicode direct sequence spread spectrum techniques in conjunction with V-BLAST. In the considered multicode V-BLAST system, the receiver experiences code domain interference (CDI) in frequency selective fading, in addition to space domain interference (SDI) experienced in conventional V-BLAST systems. We propose two interference cancelling receivers that employ a linear parallel interference cancellation approach to handle the CDI, followed by conventional V-BLAST detector to handle the SDI, and then evaluate their bit error rates.","Title: Multimedia Communication Over Ofdm Mobile Wireless Networks: A Cross-Layer Diversity Approach\nYear: 2005\n\nAbstract: Diversity can be used to combat multipath fading and improve the performance of mobile wireless multimedia communication systems. In this work, by considering transmission of an embedded bitstream over a slow varying Rayleigh faded environment, we develop a cross-layer diversity technique which takes advantage of both multiple description source coding and frequency diversity techniques. More specifically, assuming a frequency-selective channel, we study the packet loss behavior of an OFDM system and construct multiple independent descriptions using an FEC-based strategy. We demonstrate the superior performance of this approach using the Set Partitioning in Hierarchical Trees (SPIHT) coder.","Title: Performance Analysis of a Pre-BLAST-DFE Technique for MISO Channels With Decentralized Receivers\nYear: 2007\n\nAbstract: The performance of a pre-Bell Laboratories Layered Space-Time Architecture (BLAST)-decision feedback equalization (DFE) technique with Tomlinson-Harashima precoding and decentralized receivers, operating over multiple-input single-output (MISO) frequency-selective fading channels, is evaluated. First, we derive the probability of symbol error for Tomlinson-Harashima precoding operating over single...","Title: An algorithm for wireless relay placement\nYear: 2009\n\nAbstract: An algorithm is given for placing relays at spatial positions to improve the reliability of communicated data in a sensor network. The network consists of many power-limited sensors, a small set of relays, and a receiver. For each sensor, the receiver receives a direct signal as well as an indirect signal from one of the available relays. The relays rebroadcast the transmissions in order to achieve diversity at the receiver. Both amplify-and-forward and decode-and-forward relay networks are considered. Channels are modeled with Rayleigh fading, path loss, and additive white Gaussian noise. Performance analysis and numerical results are given.","Title: Concatenated block codes for unequal error protection of embedded bit streams.\nYear: 2012\n\nAbstract: A state-of-the-art progressive source encoder is combined with a concatenated block coding mechanism to produce a robust source transmission system for embedded bit streams. The proposed scheme efficiently trades off the available total bit budget between information bits and parity bits through efficient information block size adjustment, concatenated block coding, and random block interleavers. The objective is to create embedded codewords such that, for a particular information block, the necessary protection is obtained via multiple channel encodings, contrary to the conventional methods that use a single code rate per information block. This way, a more flexible protection scheme is obtained. The information block size and concatenated coding rates are judiciously chosen to maximize system performance, subject to a total bit budget. The set of codes is usually created by puncturing a low-rate mother code so that a single encoder-decoder pair is used. The proposed scheme is shown to effectively enlarge this code set by providing more protection levels than is possible using the code rate set directly. At the expense of complexity, average system performance is shown to be significantly better than that of several known comparison systems, particularly at higher channel bit error rates.","Title: Asymptotic Performance Of Digital Communication Over Fading Channels\nYear: 2007\n\nAbstract: This paper(1) presents a simple way to obtain the asymptotic performance of various digital communications systems operating over fading channels. The resulting expression for performance contains only the inverse average SNR raised to the system's diversity order, by averaging the conditional error probability (conditioned on the fading) with the dominant term in the fading density function. The proposed approach often renders simple closed-form asymptotic error probabilities (ASEPs), even when the corresponding closed-form actual error probabilities (ACEPs) are too difficult to find, such as those in generalized selection combining, denoted by GSC(m, L), where the strongest m branches from L (1 <= m <= L) total branches are selected and combined. Using the proposed approach, the paper derives simple closed-form ASEPs for GSC(m, L) which show its diversity order and SNR gaps among different m, over both iid and non-iid Rayleigh fading channels for both MPSK and QAM. It is found that the SNR gaps of GSC(m,L) are not a function of modulation type or orders. In addition, the paper also presents simple closed-form ASEPs for a Nakagami-m fading channel with both MPSK and QAM in conjunction with maximal ratio combining (MRC).","Title: Optimal Allocation Of Bandwidth For Minimum Battery Consumption\nYear: 2005\n\nAbstract: In general, a power amplifier utilizes battery energy more efficiently with a higher transmission power. For a given message, a given bandwidth constraint and a given performance constraint, different allocations of the bandwidth among source coding, channel coding and modulation result in different amounts of battery usage. We propose a method to optimize the bandwidth allocation and minimize the battery consumption due to transmission. Our results show that with the optimal allocation, significant reduction in battery consumption can be achieved without sacrificing the system performance.","Title: Delay analysis of block coded transmission over the Gilbert-Elliott channel with interleaving and retransmission strategy\nYear: 2000\n\nAbstract: To determine the end-to-end delay in block coded transmission over the Gilbert-Elliott (1960, 1963) channel with interleaving and a retransmission strategy, the probability distribution of the number of transmissions that a packet has to go through before it succeeds has to be found. We propose an approximate method to evaluate the distribution when the error statistics are dependent. The end-to-end delay is then examined. Our study provides a way to choose an error-control scheme (i.e., an interleaver of an appropriate size with a retransmission protocol), which meets both the delay constraint and a reliability requirement","Title: Minimization of Expected Distortion with Layer-Selective Relaying of Two-Layer Superposition Coding.\nYear: 2013\n\nAbstract: This paper considers a relay system using two-layer superposition coding to minimize the expected distortion of a Gaussian source at the destination node. For the system, we propose two types of layer- selective relaying based on the local decoding result at the relay and the decoding result at the destination node fed back to the relay. One type of the proposed scheme uses decode-and-forward (DF) in the design of the relay signals, while the other type uses both DF and amplify-and-forward (AF). For the proposed scheme, we analyze the outage probabilities and evaluate the expected distortion according to the relay location. The results reveal that the proposed scheme improves the finite SNR performance, in particular when the relay node is closer to the source node than it is to the destination node.","Title: Video coding for a time varying tandem channel with feedback\nYear: 2005\n\nAbstract: Summary form only given. A robust scheme for the efficient transmission of packet video over a tandem wireless Internet channel is extended to a time varying scenario with a feedback channel. This channel is assumed to have bit errors (due to noise and fading on the wireless portion of the channel) and packet erasures (due to congestion on the wired portion). Simulation results showed that refined estimation can dramatically improve the performance for varying channel conditions, and that combined feedback of both channel conditions and ACK/NACK information can further improve system performance compared with the feedback of just one type of information.","Title: A Markov Model for Block Errors on Fading Channels\nYear: 1996\n\nAbstract: — In this paper, we investigate the behavior of block errors which arise in data transmission on fading channels. Our approach is more detailed than previous studies, in that it takes into account the specific coding/modulation scheme and it tracks the fading process symbol by symbol. It is shown that a Markov approximation for the block error process (possibly degenerating into an iid process for sufficiently fast fading) is a very good model for a broad range of parameters. Also, it is observed that the relationship between the marginal error rate and the transition probability is largely insensitive to pa ram- eters such as block length, degree of forward error correction and modulation format, and only depends on an appropriately normalized version of the Doppler frequency. This observation leads to a unified approach for the channel modeling which simplifies the performance analysis of upper-layer protocols.","Title: Cross-layer distributed joint power control and scheduling for delay-constrained applications over CDMA-based wireless ad-hoc networks\nYear: 2010\n\nAbstract: In this paper, we propose a cross-layer distributed power control and scheduling protocol for delay-constrained applications over mobile CDMA-based ad hoc wireless networks. Herein, we propose a novel scheme where power control is employed to combat delay occurring on multi-hop wireless ad hoc networks via cross-layer information exchange. Based on that, a distributed power control and scheduling protocol is proposed to control the incurred delay as well as the multiple access interference (MAI). Unlike other previous work on power control and scheduling, we also investigate the impact of Doppler spread upon the system performance, and provide a robust system which employs a combination of power control, and coding/interleaving to combat the effects of Doppler spread by exploiting the time diversity when the Doppler spread gets large. Hence, our proposed approach can function appropriately over a wide range of channel conditions.","Title: Weight distribution of a class of binary block codes formed from RCPC codes.\nYear: 2005\n\nAbstract: In this paper, we study the weight enumerator and the numerical performance of a class of binary linear block codes formed from a family of rate-compatible punctured convolutional (RCPC) codes. Also, we present useful numerical results for a well-known family of RCPC codes.","Title: A First-Order Markov Model For Correlated Nakagami-M Fading Channels\nYear: 2002\n\nAbstract: In this paper, we propose a first-order Markov model for generalized Nakagami-m flat fading channels. Using a moment generating function (MGF) approach, we derive the parameters of the proposed model for any value of the fading severity index m greater than or equal to 0.5. The proposed model is a generalized version of the one proposed earlier by Zorzi et al for flat Rayleigh fading channels. For m = 1, we show that our generalized model gives the same parameter values obtained using Zorzi's approach. Our generalized model thus encompasses Zorzi's model as a special case. We illustrate the usefulness of our proposed Markov model by applying it to the analysis of the throughput and energy efficiency performance of a link layer (LL) protocol with backoff on wireless fading links with different values of the m-parameter (= 0.5,1,4).","Title: Performance Analysis Of N-Channel Symmetric Fec-Based Multiple Description Coding For Ofdm Networks\nYear: 2011\n\nAbstract: Recently, multiple description source coding has emerged as an attractive framework for robust multimedia transmission over packet erasure channels. In this paper, we mathematically analyze the performance of n-channel symmetric FEC-based multiple description coding for a progressive mode of transmission over orthogonal frequency division multiplexing (OFDM) networks in a frequency-selective slowly-varying Rayleigh faded environment. We derive the expressions for the bounds of the throughput and distortion performance of the system in an explicit closed form, whereas the exact performance is given by an expression in the form of a single integration. Based on this analysis, the performance of the system can be numerically evaluated. Our results show that at high SNR, the multiple description encoder does not need to fine-tune the optimization parameters of the system due to the correlated nature of the subcarriers. It is also shown that, despite the bursty nature of the errors in a slow fading environment, FEC-based multiple description coding without temporal coding provides a greater advantage for smaller description sizes.","Title: Performance Analysis of Optimum and Suboptimum Selection Diversity Schemes on Rayleigh Fading Channels With Imperfect Channel Estimates\nYear: 2007\n\nAbstract: In this paper, we present a comparative analysis on the effects of channel estimation errors on the performance of optimum and suboptimum selection diversity (SD) receivers on Rayleigh-fading channels. By modeling the estimation errors as independent complex Gaussian random variables, we derive simple closed-form expressions for the average probability of error for both optimum and suboptimum SD s...","Title: Superposition MIMO Coding for the Broadcast of Layered Sources.\nYear: 2011\n\nAbstract: We propose superposition multiple-input multiple-output (MIMO) coding for the transmission of unequally important sources in a point-to-multipoint system. First, a tradeoff between Alamouti code and spatial multiplexing (V-BLAST) is analyzed in terms of the average bit error rate (BER), where the maximum data rates of both MIMO schemes are set to be equal. The results show that for a given target ...","Title: Optimal Sensing Disruption for a Cognitive Radio Adversary\nYear: 2010\n\nAbstract: Spectrum sensing vulnerabilities in cognitive radio (CR) networks are being actively investigated, where most research focuses on mechanisms that deal with possible attacks without examining optimal sensing disruption strategies. This paper addresses the optimal design and analysis of a power-limited intelligent adversary to a CR network. The adversary targets unused bands and puts energy into them so that the number of unused bands appears reduced to secondary users. This is called sensing disruption. The optimal disruption strategy is obtained by maximizing the average number of false detections under the adversary's power constraint. It is shown that, for a CR network where energy detection is utilized by secondary users, the optimal sensing disruption strategy for noise spoofing for a CR adversary is equal-power partial-band spoofing. Numerical results and analyses of the optimal sensing disruption are provided.","Title: Performance Of Space-Time Spreading With Correlated Fading And Channel Estimation\nYear: 2002\n\nAbstract: Space-time block codes (STBC) have been proposed as a less complex alternative to space-time trellis codes for achieving transmit diversity. Application of such STBCs to code division multiple access (CDMA) systems is called space-time spreading (STS). STS schemes have been considered under the assumption of independent transmit fades and ideal channel state information (CSI). However, the performance of these schemes deteriorates when the above assumptions are relaxed in a realistic system. We study here analytic-ally the performance degradation due to both the fade correlation and the channel estimation errors.","Title: Statistical modeling of W-CDMA signals for use over frequency-selective multipath channels\nYear: 2004\n\nAbstract: This letter presents a mathematical model for the statistics of wideband code-division multiple-access signals which experience multipath fading. The statistics are obtained from numerically generated signals, and are then modeled with an offset noncentral chi distribution with three degrees of freedom. The mathematical model is tested against the numerically generated data by the use of a chi-squ...","Title: Guest editorial: wireless video transmission\nYear: 2010\n\nAbstract: The 20 papers in this special issue on wireless video transmissions are divided into four categories: wireless video streaming, optimization and scheduling; wireless video broadcast/multicast; retransmission techniques; and video quality assessment.","Title: Special issue on evolving from 3G deployment to 4G definition.\nYear: 2002\n\nAbstract: The deployment of 3G mobile systems is now getting underway, with roll-out plans being affected by a number of mutually reinforcing factors. These factors include policies affecting the business case for operators who need to erate return on their investment in infrastructure within a reasonable time span, and the general economic situation impacting the propensity of operators to take such infrastructure investment risks coupled with the propensity of end to pay for new and improved services. This is all taking place in an environment where expectations have, for many years, followed the technology curve of rapidly improving performance and capability at steadily declining cost.","Title: Chernoff-Type Bounds for the Gaussian Error Function.\nYear: 2011\n\nAbstract: We study single-term exponential-type bounds (also known as Chernoff-type bounds) on the Gaussian error function. This type of bound is analytically the simplest such that the performance metrics in most fading channel models can be expressed in a concise closed form. We derive the conditions for a general single-term exponential function to be an upper or lower bound on the Gaussian error functio...","Title: Optimized Unequal Error Protection Using Multiplexed Hierarchical Modulation\nYear: 2012\n\nAbstract: With progressive image or scalable video encoders, as more bits are received, the source can be reconstructed with progressively better quality. These progressive codes have gradual differences of importance in their bitstreams, which necessitates multiple levels of unequal error protection (UEP). One practical method of achieving UEP is based on a constellation of nonuniformly spaced signal points, or hierarchical constellations. However, hierarchical modulation can achieve only a limited number of UEP levels for a given constellation size. Though hierarchical modulation has been intensively studied for digital broadcasting or multimedia transmission, most work has considered only two layered source coding, and methods of achieving a large number of UEP levels for progressive transmission have rarely been studied. In this paper, we propose a multilevel UEP system using multiplexed hierarchical quadrature amplitude modulation (QAM). We show that multiple levels of UEP are achieved by the proposed multiplexing method. When the BER is dominated by the minimum Euclidian distance, we derive an optimal multiplexing approach which minimizes both the average and peak powers. We next propose an asymmetric hierarchical QAM which reduces the peak-to-average power ratio (PAPR) of the proposed UEP system without any performance loss. Numerical results show that the performance of progressive transmission over Rayleigh fading channels is significantly enhanced by the proposed methods.","Title: Channel coding for progressive images in a 2-D time-frequency OFDM block with channel estimation errors.\nYear: 2009\n\nAbstract: Coding and diversity are very effective techniques for improving transmission reliability in a mobile wireless environment. The use of diversity is particularly important for multimedia communications over fading channels. In this work, we study the transmission of progressive image bitstreams using channel coding in a 2-D time-frequency resource block in an OFDM network, employing time and frequency diversities simultaneously. In particular, in the frequency domain, based on the order of diversity and the correlation of individual subcarriers, we construct symmetric n -channel FEC-based multiple descriptions using channel erasure codes combined with embedded image coding. In the time domain, a concatenation of RCPC codes and CRC codes is employed to protect individual descriptions. We consider the physical channel conditions arising from various coherence bandwidths and coherence times, leading to a range of orders of diversities available in the time and frequency domains. We investigate the effects of different error patterns on the delivered image quality due to various fade rates. We also study the tradeoffs and compare the relative effectiveness associated with the use of erasure codes in the frequency domain and convolutional codes in the time domain under different physical environments. Both the effects of intercarrier interference and channel estimation errors are included in our study. Specifically, the effects of channel estimation errors, frequency selectivity and the rate of the channel variations are taken into consideration for the construction of the 2-D time-frequency block. We provide results showing the gain that the proposed model achieves compared to a system without temporal coding. In one example, for a system experiencing flat fading, low Doppler, and imperfect CSI, we find that the increase in PSNR compared to a system without time diversity is as much as 9.4 dB.","Title: Optimal Transmission of Progressive Sources Based on the Error Probability Analysis of SM and OSTBC\nYear: 2014\n\nAbstract: This paper studies the optimal design of multimedia progressive communication systems that are combined with low-complex open-loop multiple-input multiple-output techniques. First, we analyze the behavior of the crossover point of the error probability curves for orthogonal space-time block codes (OSTBC) and spatial multiplexing (SM) with a zero-forcing linear receiver. We mathematically prove that, in the high signal-to-noise ratio (SNR) regime, for both the information outage probability and the uncoded bit error rate, as data rate increases, the crossover point for the error probability monotonically decreases, and the crossover point for the SNR monotonically increases. We prove that this holds, regardless of the numbers of transmit and receive antennas and the spatial multiplexing rate of OSTBC. We next show how those results can be exploited for the optimal transmission of progressive sources, such as embedded image, which require unequal target error rates in their bitstream. That is, the computational complexity involved with the optimal space-time coding of progressive bitstream can be decreased.","Title: Spectrum Broadening Due to Phase Noise Interaction in Cognitive Radio Systems\nYear: 2010\n\nAbstract: Spectrum broadening due to the interaction of local oscillator (LO) phase noise with an adjacent channel signal is analyzed, and applied to the situation where a cognitive radio (CR) detector experiences in-band interference from a strong adjacent channel signal. Expressions for the resulting in-band interference and modified detection performance are presented.","Title: Enhanced Selection Combining by Choosing Independently the Strongest Real Component and the Strongest Imaginary Component of all Channels\nYear: 2014\n\nAbstract: Conventional selection combining (SC) selects the antenna with the largest channel envelope. In this paper, we propose to select the largest real part and largest imaginary part of the channel individually from all antennas for 2 dimensional (2-D) signals such as MPSK or MQAM. We derive the asymptotic symbol error rate (ASER) expression for this system and it is found that it has the same diversity order (DO) as does conventional SC, but has an SNR gain over conventional SC. The paper presents a closed-form expression for this gain, which monotonically increases with the DO, and is independent of the constellation size for a given modulation format. Simulation results are shown to match the theoretical analysis.","Title: Cooperative Relaying of Superposition Coding with Simple Feedback for Layered Source Transmission.\nYear: 2013\n\nAbstract: We consider a relay network that delivers a Gaussian source by employing successive refinement source coding and superposition coding of layers at the source node and successive decoding at the relay and destination nodes. For the network, making use of the decoding results at the relay and destination nodes of the first transmission, an efficient relaying strategy of layers is proposed to minimize the expected distortion (ED) when only the average channel state information is available at the source node. Three types of the proposed scheme, defined as Prop-DF, using decode-and-forward signals, Prop-AF, using amplify-and-forward signals, and Prop-MF, using mixed-forward signals, are addressed and analyzed in terms of the outage probability and distortion exponent. Unlike other studies, we have also taken the relay location into account in deriving the distortion exponent showing the high SNR behavior of the ED. The results show that the proposed scheme increases the distortion exponent up to twice that of the conventional relaying schemes when the relay is close to the source node, and that Prop-MF provides the best performance for most relay locations.","Title: Multi-User Resource Allocation for Downlink Multi-Cluster Multicarrier DS CDMA System.\nYear: 2011\n\nAbstract: In this paper, we consider an adaptive multi-user resource allocation for the downlink transmission of a multi-cluster tactical multicarrier DS CDMA network. The goal is to maximize the sum packet throughput, subject to transmit power constraints. Since the objective function turns out to be noncovex and nondifferentiable, we propose a simple iterative bisection algorithm. At each iteration, a clo...","Title: The effects of channel estimation errors on a nonlinear precoder for multiple antenna downlink channels\nYear: 2009\n\nAbstract: The effects of channel estimation errors on the performance of a system employing Tomlinson-Harashima precoding and the QR decomposition, operating over multiple antenna frequency-flat fading channels with decentralized receivers, is evaluated. The QR decomposition of the channel matrix is employed to arrive at an equivalent channel where successive interference cancellation at the transmitter can be used to remove the effect of the multiuser interference. However, in the case of imperfect channel estimation, it is not possible to remove the effect of the multiuser interference due to a mismatch between the precoder and the channel. Consequently, it is necessary to include the estimation error in deriving the probability of symbol error. We also provide simulations to corroborate the analytical results.","Title: Error-resilient video communications over CDMA networks with a bandwidth constraint.\nYear: 2006\n\nAbstract: We present an adaptive video transmission scheme for use in a code-division multiple-access network, which incorporates efficient bandwidth allocation among source coding, channel coding, and spreading under a fixed total bandwidth constraint. We derive the statistics of the received signal, as well as a theoretical bound on the packet drop rate at the receiver. Based on these results, a bandwidth allocation algorithm is proposed at the packet level, which incorporates the effects of both the changing channel conditions and the dynamics of the source content. Detailed simulations are done to evaluate the performance of the system, and the sensitivity of the system to estimation error is presented.","Title: Source-channel rate optimization for progressive image transmission over block fading relay channels [Transactions Papers]\nYear: 2010\n\nAbstract: In this paper, we are concerned with the design and analysis of joint source-channel coding schemes for block fading channels with relay-assisted distributed spatial diversity. Assuming a progressive image coder with a constraint on the transmission bandwidth, we formulate a joint source-channel rate allocation scheme that maximizes the expected source throughput. Specifically, using Gaussian as well as BPSK inputs on flat Rayleigh fading channels, we lower bound the average packet error rate by the corresponding mutual information outage probability, and derive the average throughput expression as a function of channel code rates as well as channel SNR for both a frequency-division multiplexing-based baseline system without relaying, and a half-duplex relay system with a decode-and- forward protocol. At high signal-to-noise ratio (SNR), for the systems considered in this paper, we show that our rate optimization problem is a convex function of the channel code rates, and we show that a known recursive algorithm can be used to predict the performance of both systems.","Title: Asymptotic Symbol Error Rate for Selection Combining on Nakagami-m Fading Channels\nYear: 2008\n\nAbstract: This paper derives closed-form asymptotic symbol error rates (ASERs) for MPSK and MQAM signals with selection combining (SC) over Nakagami-m fading channels. It also presents a closed-form expression for the power loss of SC compared to maximal ratio combining (MRC) over a Nakagami-m fading channel. It is found that this power gap is a function of only the number (L) of independent Nakagami-m channels and the fading parameter m. For a fixed m, the gap monotonically increases with L. For a fixed L, the gap monotonically increases with m and approaches 10log(10) L dB (the asymptotic gap between MRC and SC in an AWGN channel) as m -> infinity. In addition, numerical results show the accuracy of the ASERs obtained from closed-form expressions for both MRC and SC with MPSK and MQAM signals for large SNRs. They also show that the SNR gap is identical to that predicted by the analysis for arbitrary L and m.","Title: Cross Layer Resource Allocation Design for Uplink Video OFDMA Wireless Systems\nYear: 2011\n\nAbstract: We study an uplink video communication system with multiple users in a centralized wireless cell. The multiple access scheme is Orthogonal Frequency Division Multiple Access (OFDMA). Both physical layer channel state information (CSI) and application layer rate distortion (RD) information of video streams are collected by the base station. With the goal of minimizing the average video distortion across all the users in the system, we design an iterative resource allocation algorithm for subcarrier assignment and power allocation. Based on the physical layer resource allocation decision, the user will adapt the application layer video source coding rate. To show the advantage of this cross layer algorithm, numerical results are compared with two baseline resource allocation algorithms using only physical layer information or only application layer information. Bit-level simulation results are presented which take into account the imperfection of the video coding rate control, as well as channel errors.","Title: Parallel acquisition of spread-spectrum signals with antenna diversity\nYear: 1997\n\nAbstract: The use of antenna diversity is investigated for improving the parallel acquisition performance of a direct-sequence spread-spectrum signal in both flat and frequency-selective fading channels. Noncoherent combining techniques are analyzed because coherent diversity techniques, such as maximal ratio combining, cannot be employed prior to initial acquisition. A major application of this work is to cellular communications","Title: Performance Degradation Due to MAI in OFDMA-Based Cognitive Radio\nYear: 2010\n\nAbstract: We consider a convolutionally coded orthogonal frequency-division multiple access (OFDMA) based cognitive radio system where each user achieves perfect synchronization for its own signal, while different users are asynchronized due to random timing offsets. The presence of asynchronous secondary users introduces potential multiple access interference (MAI) to each primary user's receiver. The strength of the MAI is determined by the secondary users' transmission powers, and their distances and frequency separations to the primary user. Expressions for the primary user's pairwise error probability and average probability of error are derived, and an error floor prediction method is presented. Finally, the trade-off between the MAI to the primary user and the secondary users' performances are investigated through numerical examples and simulations.","Title: Multicarrier CDMA overlay for ultra-wideband communications\nYear: 2004\n\nAbstract: In this letter, the performance of multicarrier code-division multiple-access (CDMA) systems is studied in the presence of narrowband interference for future ultra-wideband (UWB) communications. A Nakagami fading channel is assumed, and notch filters along with diversity techniques are used in the multicarrier CDMA receiver. A complete performance analysis of error probability is given. It is shown that when the number of subcarriers jammed by narrowband interference is small, the multicarrier receiver without notch filters can work well, due to the gain of frequency diversity from nonjammed subcarriers. On the other hand, when the number of subcarriers jammed by the narrowband interference is large, using notch filters can improve the multicarrier system performance significantly.","Title: Uplink Resource Management for Multiuser OFDM Video Transmission Systems: Analysis and Algorithm Design\nYear: 2013\n\nAbstract: We consider a multiuser OFDM system in which users want to transmit videos via a base station. The base station knows the channel state information (CSI) as well as the rate distortion (RD) information of the video streams and tries to allocate power and spectrum resources to the users according to both physical layer CSI and application layer RD information. We derive and analyze a condition for the optimal resource allocation solution in a continuous frequency response setting. The optimality condition for this cross layer optimization scenario is similar to the equal slope condition for conventional video multiplexing resource allocation. Based on our analysis, we design an iterative subcarrier assignment and power allocation algorithm for an uplink system, and provide numerical performance analysis with different numbers of users. Comparing to systems with either only physical layer or only application layer information available at the base station, our results show that the user capacity and the video PSNR performance can be increased significantly by using cross layer design. Bit-level simulations which take into account the imperfection of the video coding rate control, the variation of RD curve fitting, as well as channel errors, are presented.","Title: Design of multi-input multi-output systems based on low-density Parity-check codes\nYear: 2005\n\nAbstract: We design serial concatenated multi-input multi-output systems based on low-density parity-check (LDPC) codes. We employ a receiver structure combining the demapper/detector and the decoder in an iterative fashion. We consider the a posteriori probability (APP) demapper, as well as a suboptimal demapper incorporating interference cancellation with linear filtering. Extrinsic information transfer (...","Title: A Multiple Description Coding and Delivery Scheme for Motion-Compensated Fine Granularity Scalable Video\nYear: 2008\n\nAbstract: Motion-compensated fine-granularity scalability (MC-FGS) with leaky prediction has been shown to provide an efficient tradeoff between compression gain and error resilience, facilitating the transmission of video over dynamic channel conditions. In this paper, we propose an n-channel symmetric motion-compensated multiple description (MD) coding and transmission scheme for the delivery of scalable video over orthogonal frequency division multiplexed systems, utilizing the concepts of partial and leaky predictions. We investigate the proposed MD coding and transmission scheme using a cross-layer design perspective. In particular, we construct the symmetric motion-compensated MD codes based on the diversity order of the channel, defined as the ratio of the overall bandwidth of the system to the coherence bandwidth of the channel. We show that knowing the diversity order of a physical channel can assist an MC-FGS video coder in selecting the motion-compensation prediction point, as well as on the use of leaky prediction. More importantly, we illustrate how the side information can reduce the drift management problem associated with the construction of symmetric motion-compensated MD codes. We provide results based on both an information-theoretic approach and simulations.","Title: A resource allocation algorithm for real-time streaming in cognitive networks\nYear: 2009\n\nAbstract: Cognitive radios have been proposed as a means to implement efficient reuse of the licensed spectrum. Commonly, wireless networks are characterized by a fixed spectrum assignment policy. The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. We consider a simple single-cell scenario with two data up-links, one licensed to use the spectral resource (primary) and the other unlicensed (secondary or cognitive). It is assumed that the cognitive user accesses the channel only when the channel is sensed idle. An ON-OFF channel model is used for the primary link, where traffic statistical characteristics are taken into account. We study a practical resource allocation algorithm that assigns the uplink to the secondary users according to a channel-and-queues aware scheduler when primary link OFF periods are sensed. We fit the resource allocation algorithm to the widely investigated orthogonal frequency division multiple access (OFDMA) scheme and we exploit multiuser diversity by applying a smart power allocation within independent OFDMA subchannels. A video encoder rate control is introduced in order to limit the video frame loss due to overflow that trades the video frame loss probability with the overall encoding quality. Lastly, the performance of the cognitive network model is investigated under the proposed resource allocation algorithm.","Title: Cooperative and Constrained MIMO Communications in Wireless Ad Hoc/Sensor Networks\nYear: 2010\n\nAbstract: In this paper, we investigate the issue of cooperative node selection in MIMO communications for wireless ad hoc/sensor networks, where a source node is surrounded by multiple neighbors and all of them are equipped with a single antenna. Given energy, delay and data rate constraints, a source node dynamically chooses its cooperating nodes from its neighbors to form a virtual MIMO system with the destination node (which is assumed to have multiple antennas), as well as adaptively allocates the power level and adjusts the constellation size for each of the selected cooperative nodes. In order to optimize system performance, we jointly consider the optimization of all these parameters, given the aforementioned system constraints. We assume that the source node either has CSI, or has no CSI. Heuristic algorithms, such as maximal channel gain (MCG) and least channel correlation (LCC) algorithms are proposed in order to exploit available system information and to solve the constrained optimization problem.","Title: Tradeoff between diversity gain and interference suppression in a MIMO MC-CDMA system\nYear: 2005\n\nAbstract: In this paper, the uplink of an asynchronous multi-carrier direct-sequence code-division multiple-access (MC-DS-CDMA) system with multiple antennas at both the transmitter and the receiver is considered. We analyze the system performance over a spatially correlated Rayleigh fading channel with multiple-access interference (MAI), and evaluate the antenna array performance with joint fading reductio...","Title: MMSE interference suppression for coded multicarrier DS-CDMA in the presence of intermodulation\nYear: 1999\n\nAbstract: This paper presents a coded multicarrier (MC) DS-CDMA system which, by the use of a linear convolutional code (CC) and minimum mean-squared error (MMSE) receiver, achieves frequency diversity instead of path diversity as in a conventional single carrier RAKE DS-CDMA, and has the ability to partially compensate for the distortion introduced by a nonlinear amplifier at the transmitter. A frequency selective Rayleigh fading channel is decomposed into M frequency non-selective channels, based on the channel coherence bandwidth. A rate 1/M convolutional code, after being interleaved, is used to modulate M different DS-CDMA waveforms. The new system is shown to effectively suppress multiple access interference in the presence of intermodulation distortion","Title: The effects of spatial diversity and imperfect channel estimation on wideband MC-DS-CDMA and MC-CDMA\nYear: 2009\n\nAbstract: In our previous work, we compared the theoretical bit error rates of multi-carrier direct sequence code division multiple access (MC-DS-CDMA) and multi-carrier code division multiple access (MC-CDMA). To ensure a fair comparison, we constrained both schemes to the same bandwidth, information rate, and energy-per-bit, and these constraints resulted in a possible trade-off between diversity gain and channel estimation errors between the two schemes. While only a single-input single-output (SISO) system was considered in our previous work, in this paper, we extend the comparison to a multiple-input multiple-output (MIMO) system which employs Alamouti space-time block coding at each sub-carrier frequency to achieve spatial diversity. We consider only those cases where MC-CDMA has higher frequency diversity than MC-DS-CDMA. Since increases in diversity yield diminishing gains, we conclude that the addition of spatial diversity to this multi-carrier comparison benefits MCDS-CDMA more than MC-CDMA. To determine whether these gains for MC-DS-CDMA are enough to offset the difference in frequency diversity between the two schemes, we derive closed-form expressions for the bit error probabilities of both schemes, and we compare the MIMO results against those of the SISO system for different information rates, number of users, and number of pilot symbols per channel estimate.","Title: Optimal Linear-Combining Receiver For Decode-And-Forward Relays Using Superposition Coding\nYear: 2013\n\nAbstract: We consider a relay network with a single source, a single destination, and multiple relays. The relays are half-duplex and use the decode-and-forward protocol. A layered Gaussian source partitioned into two layers is transmitted. The source broadcasts a message consisting of two layers to all the relays using superposition coding. Each relay re-encodes and forwards all its successfully decoded layers to the destination using an orthogonal channel. Superposition coding is used only if both layers are forwarded. We propose a novel approach to derive the optimal linear-combining receiver at the destination. Numerical results show that the two-layer scheme using superposition coding outperforms a conventional one-layer scheme in terms of average throughput and expected distortion.","Title: Trade-Off Between Diversity and Channel Estimation Errors in Asynchronous MC-DS-CDMA and MC-CDMA\nYear: 2008\n\nAbstract: This paper investigates the trade-off between diversity and channel estimation errors for asynchronous multi-carrier CDMA (MC-CDMA) and multicarrier direct-sequence CDMA (MC-DS-CDMA). We construct a side-by-side comparison between the two systems by assuming equal operating and channel conditions. Both systems perform pilot-symbol- aided channel estimation and maximal ratio combining at the receiv...","Title: Motion-Compensated Scalable Video Transmission Over MIMO Wireless Channels\nYear: 2013\n\nAbstract: We study motion compensated fine granular scalable (MC-FGS) video transmission over multiinput multioutput (MIMO) wireless channels applicable to video streaming, where leaky and partial prediction schemes are applied in the enhancement layer of MC-FGS to exploit the tradeoff between error propagation and coding efficiency. For reliable transmission, we propose unequal error protection (UEP) by considering a tradeoff between reliability and data rates, which are controlled by forward error correction and MIMO mode selection to minimize the average distortion. In a high Doppler environment, where it is hard to get an accurate channel estimate, we investigate the performance of the proposed MC-FGS video transmission scheme with joint control of both the leaky and partial prediction parameters, and the UEP. In a slow fading channel, where the channel throughput can be estimated at the transmitter, adaptive control of prediction parameters is considered.","Title: Coarse Acquisition Performance of Spectral-Encoded UWB Communication Systems in the Presence of Narrow-Band Interference.\nYear: 2007\n\nAbstract: It is known that a major practical implementation challenge of ultra-wideband (UWB) receivers is the design of the coarse acquisition stage. Due to the fine time resolution of UWB signals, the acquisition stage has to acquire a large number of low-energy multipath components, with no or little knowledge of the state of the channel. In addition, the complexity further increases with the presence of...","Title: Tradeoffs of Source Coding, Channel Coding and Spreading in Frequency Selective Rayleigh Fading Channels\nYear: 2002\n\nAbstract: This paper investigates the tradeoffs of source coding, channel coding and spreading in CDMA systems. We consider a system consisting of an image source coder, a convolutional channel coder, an interleaver, and a direct sequence spreading module. With different allocations of bandwidth to source coding, channel coding and spreading, the system is analyzed over a frequency selective Rayleigh fading channel. The performance of the system is evaluated using the cumulative distribution function of peak signal-to-noise ratio. Tradeoffs of different components of the system are determined through simulations. We show that, for a given bandwidth, an optimal allocation of that bandwidth can be found. Tradeoffs among the parameters allow us to tune the system performance to specific requirements.","Title: Higher Order Constellation with Simplified Minimum Mean Square Error (MMSE) Receiver in CDMA Channel with Tone Interference\nYear: 2000\n\nAbstract: It has previously been shown that employing a higher order constellation in conjunction with CDMA can improve the performance of the multiuser system in the presence of severe ISI and narrowband Gaussian interference. We study a similar scenario here, except that the narrowband Gaussian interferer is replaced with a tone interferer. It is shown that the use of the higher order alphabet size is also useful in the tone interference case. Also, we derive lower and upper bounds on the performance of an MMSE receiver in a multiuser, flat fading scenario. Later we apply the same technique to a multiuser, frequency selective fading scenario with negligible or mild ISI.","Title: Adaptive Modulation for OFDM-Based Multiple Description Progressive Image Transmission\nYear: 2008\n\nAbstract: This paper addresses the use of adaptive modulation in progressive image transmission with multiple description coding in conjunction with an Orthogonal Frequency Division Multiplexing (OFDM) system. Specifically, two adaptive systems are considered: variable rate with fixed power, and variable rate with variable power. An algorithm is proposed to allocate power and constellation size at each subchannel by maximizing the throughput. Simulation results confirm that cross-layer optimization with adaptive modulation enhances system performance.","Title: Simple closed-form asymptotic symbol error rate of selection combining and its power loss compared to the maximal ratio combining over Nakagami m fading channels\nYear: 2010\n\nAbstract: This paper derives closed-form asymptotic symbol error rates (ASERs) for MPSK and MQAM signals with selection combining (SC) over Nakagami-m fading channels. It also presents a closed-form expression for the power loss of SC compared to maximal ratio combining (MRC) over a Nakagami- m fading channel. It is found that this power gap is a function of only the number (L) of independent Nakagami-m channels and the fading parameter m. For a fixed m, the gap monotonically increases with L. For a fixed L, the gap monotonically increases with m and approaches 10 log10 L dB (the asymptotic gap between MRC and SC in an AWGN channel) as m ¿ ¿. In addition, numerical results show the accuracy of the ASERs obtained from closed-form expressions for both MRC and SC with MPSK and MQAM signals for large SNRs. They also show that the SNR gap is identical to that predicted by the analysis for arbitrary L and m.","Title: Channel Coding Optimization Based on Slice Visibility for Transmission of Compressed Video over OFDM Channels.\nYear: 2012\n\nAbstract: Optimization of multimedia transmissions over wireless channels should be aimed at maximizing the video quality perceived by the final user. For transmission of video sequences over an orthogonal frequency division multiplexing (OFDM) system in a slowly varying Rayleigh faded environment, we develop a cross-layer technique, based on a slice loss visibility (SLV) model used to evaluate the visual importance of each slice. In particular, taking into account the visibility scores available from the bitstream, depending on the scenario, we optimize the mapping of video slices within a 2-D time-frequency resource block and/or the channel code rates, in order to better protect more visually important slices. The proposed algorithm is investigated for several scenarios, with different levels of information about the channel available in the optimization process. Results demonstrate that, for different physical environments and different video sequences, the proposed algorithm outperforms baseline ones which do not take into account either the SLV or the CSI in the video transmission.","Title: On Uplink Channel Estimation in WiMAX Systems\nYear: 2010\n\nAbstract: In this paper, channel estimation algorithms are proposed and compared for uplink WiMAX systems, which are OFDMA based. These algorithms are investigated based on a dynamic resource allocation scheme, and it is shown that each of them is suitable to specific system scenarios. For example, for a system with a bandwidth of 10MHz operating in the low frequency region 2-11GHz, a two-dimensional averaging algorithm outperforms other algorithms, such as a bilinear interpolation algorithm, because the correlations between the pilots and signals are sufficiently high in both the frequency and the time dimensions.","Title: Multi-User Resource Allocation for a Distributed Multi-Carrier DS-CDMA Network.\nYear: 2012\n\nAbstract: This paper addresses an adaptive multi-user resource allocation for a distributed multi-carrier direct sequence-code division multiple access (MC DS-CDMA) network. The packet throughput, which turns out to be nonconvex and nondifferentiable, is considered to measure the system performance. A sub-optimal non-cooperative power control game is proposed to adaptively allocate the transmit power, available subchannels and alphabet size by minimizing the transmit power with a transmit power constraint and a packet throughput requirement. Also, the paper investigates the effect of channel estimation error on the adaptive resource allocation in a distributed MC DS-CDMA network, and shows that using the Gaussian approximation for the signal-dependent noise can lead to a nontrivial discrepancy in system performance.","Title: Joint Source-Channel Coding and Unequal Error Protection for Video Plus Depth\nYear: 2015\n\nAbstract: We consider the joint source-channel coding (JSCC) problem of 3-D stereo video transmission in video plus depth format over noisy channels. Full resolution and downsampled depth maps are considered. The proposed JSCC scheme yields the optimum color and depth quantization parameters as well as the optimum forward error correction code rates used for unequal error protection (UEP) at the packet level. Different coding scenarios are compared and the UEP gain over equal error protection is quantified for flat Rayleigh fading channels.","Title: Resource Allocation and Performance Analysis for Multiuser Video Transmission Over Doubly Selective Channels\nYear: 2015\n\nAbstract: We consider an uplink multicarrier system with multiple video users who want to send compressed video data to the base station. In the time domain, we model the time-varying channel using Jakes' model, and in the frequency domain, each subcarrier is assumed to be independently fading. The video is scalably coded in units of a group of pictures (GOP), and users have different video rate distortion (RD) functions. At the beginning of the GOP, the base station collects both the RD information and the instantaneous channel state information (CSI) for subcarrier allocation purposes. We design a cross-layer resource allocation algorithm to assign subcarriers to users based on both the demand of the video and the quality of the channel. Once the resource allocation decision is made, the users then periodically adapt the modulation format of the subcarriers allocated according to the evolution of the CSI for the duration of the GOP. We show that our cross-layer resource allocation robustly outperforms two baseline algorithms, each of which uses only one layer of information for resource allocation.","Title: Multiview coding and error correction coding for 3D video over noisy channels.\nYear: 2015\n\nAbstract: We consider the joint source–channel coding problem of stereo video transmitted over AWGN and flat Rayleigh fading channels. Multiview coding (MVC) is used to encode the source, as well as a type of spatial scalable MVC. Our goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under the constraints that the quality of the left and right views must each be greater than predetermined PSNR thresholds at the receiver. We first consider symmetric coding, for which the quality thresholds are equal. Following binocular suppression theory, we also consider asymmetric coding, for which the quality thresholds are unequal. The optimization problem is solved using both equal error protection (EEP) and a proposed unequal error protection (UEP) scheme. An estimate of the expected end-to-end distortion of the two views is formulated for a packetized MVC bitstream over a noisy channel. The UEP algorithm uses these estimates for packet rate allocation. Results for various scenarios, including non-scalable/scalable MVC, symmetric/asymmetric coding, and UEP/EEP, are provided for both AWGN and flat Rayleigh fading channels. The UEP bit savings compared to EEP are given, and the performances of different scenarios are compared for a set of stereo video sequences.","Title: Bounding The Performance Of The Lms Estimator For Cases Where Performance Exceeds That Of The Finite Wiener Filter\nYear: 1998\n\nAbstract: The least-mean-square (LMS) estimator is a nonlinear estimator with information dependencies spanning the entire set of data fed into it. The traditional analysis techniques which are used to model this estimator obscure this, restricting the estimator to the finite set of data sufficient to span the length of its filter. The finite Wiener filter is thus often considered a bound on the performance of the LMS estimator. Several papers have reported the performance of the LMS filter exceeding that of the finite Wiener filter. In this paper, we will demonstrate a bound on the LMS estimator, which does not exclude the contributions from data outside its filter length, and which demonstrates the ability of the LMS estimator to outperform the finite Wiener filter in certain cases.","Title: Spoofing optimization over Nakagami-m fading channels of a cognitive radio adversary.\nYear: 2013\n\nAbstract: We examine the performance of a cognitive radio system in a hostile environment where an intelligent adversary tries to disrupt communications by spoofing. We analyze a cluster-based network of secondary users (SUs), where sensing is performed by the cluster head. The adversary may attack during the sensing interval to limit access for SUs by transmitting a Gaussian noise spoofing signal. We present how the adversary can optimally allocate power across subcarriers during the sensing interval over Nakagami-m fading channels, using an optimization approach specific to this problem. We determine a worst-case optimal spoofing power allocation, when the adversary has knowledge of the system, which gives a lower bound to the average number of accessible bands for SUs under attack.","Title: Double-layer video transmission over decode-and-forward wireless relay networks using hierarchical modulation.\nYear: 2014\n\nAbstract: We consider a wireless relay network with a single source, a single destination, and a multiple relay. The relays are half-duplex and use the decode-and-forward protocol. The transmit source is a layered video bitstream, which can be partitioned into two layers, a base layer (BL) and an enhancement layer (EL), where the BL is more important than the EL in terms of the source distortion. The source broadcasts both layers to the relays and the destination using hierarchical 16-QAM. Each relay detects and transmits successfully decoded layers to the destination using either hierarchical 16-QAM or QPSK. The destination can thus receive multiple signals, each of which can include either only the BL or both the BL and the EL. We derive the optimal linear combining method at the destination, where the uncoded bit error rate is minimized. We also present a suboptimal combining method with a closed-form solution, which performs very close to the optimal. We use the proposed double-layer transmission scheme with our combining methods for transmitting layered video bitstreams. Numerical results show that the double-layer scheme can gain 2–2.5 dB in channel signal-to-noise ratio or 5–7 dB in video peak signal-to-noise ratio, compared with the classical single-layer scheme using conventional modulation.","Title: Optimized Spoofing and Jamming a Cognitive Radio\nYear: 2014\n\nAbstract: We examine the performance of a cognitive radio system in a hostile environment where an intelligent adversary tries to disrupt communications by minimizing the system throughput. We investigate the optimal strategy for spoofing and jamming a cognitive radio network with a Gaussian noise signal over a Rayleigh fading channel. We analyze a cluster-based network of secondary users (SUs). The adversary may attack during the sensing interval to limit access for SUs by transmitting a spoofing signal. By jamming the network during the transmission interval, the adversary may reduce the rate of successful transmission. We present how the adversary can optimally allocate power across subcarriers during sensing and transmission intervals with knowledge of the system, using a simple optimization approach specific to this problem. We determine a worst-case optimal energy allocation for spoofing and jamming, which gives a lower bound to the overall information throughput of SUs under attack.","Title: Rejection of multiple narrow-band interference in both BPSK and QPSK DS spread-spectrum systems\nYear: 1988\n\nAbstract: The performance of direct-sequence spread-spectrum systems using a suppression filter in the presence of multiple narrow band interference with rational spectral densities is analyzed. Both BPSK and QPSK systems are considered, and analytical expressions for both the means-square error of the filter output and the performance improvement are established. When the bandwidths of the narrow band components of the interference are all small, approximate expressions are obtained and used to provide further insight into the behavior of the system. Results are presented for the limiting case when the bandwidths approach aero (i.e. when multiple narrow band interference becomes multiple sinusoidal interference). >","Title: Maximum-likelihood estimation of the angular position and extent of a target\nYear: 1981\n\nAbstract: The maximum-likelihood estimates of the angular position and angular extent of a target relative to the boresight of a monopulse radar system is derived, and the statistics of the estimates are determined. It is shown that the moments of the estimates do not exist when the thermal noise power in the receiver is nonzero. However, conditional moments are determined which do exist, as well as conditional density and/or distribution functions.","Title: SNR estimation in Nakagami-m fading with diversity combining and its application to turbo decoding\nYear: 2002\n\nAbstract: We propose an online signal-to-noise ratio (SNR) es- timation scheme for Nakagami- fading channels with branch equal gain combining (EGC) diversity. We derive the SNR estimate based on the statistical ratio of certain observables over a block of data, and use the SNR estimates in the iterative decoding of turbo codes on Nakagami- fading channels with branch EGC diversity. We evaluate the turbo decoder performance using the SNR estimate under various fading and diversity scenarios ( and ) and compare it with the performance using perfect knowledge of the SNR and the fade amplitudes. Index Terms—Diversity, Nakagami fading, SNR estimation, turbo codes.","Title: Multicarrier CDMA system with cochannel interference cancellation\nYear: 1994\n\nAbstract: In a conventional quasi-synchronous system, synchronized users, so-called in-sync users, experience less interference than do out of sync users. The authors propose a new technique to cancel the cochannel interference for an out-of-sync user in the forward link of a cellular CDMA system. They use multicarrier direct sequence waveforms, which can yield both robustness against multipath fading and narrowband interference suppression, in addition to cochannel interference suppression","Title: Performance of Meteor-Burst Communication Channels\nYear: 1987\n\nAbstract: In this paper, we briefly describe the physical characteristics of a meteor-burst (MB) communication channel, and then present the results of an analysis showing the expected throughput and the probability of completing a given message under two different scenarios. In the first scenario, the transmitter is presumed to have knowledge (obtained by appropriate probe signals) of the entire duration of a given MB. In the second, only the starting time of each MB is known. Numerical results based on the analysis are provided, and it is shown what types of delays must be tolerated in order to achieve a given degree of reliability of having the transmitted message correctly received at its destination.","Title: Further results on selection combining of binary NCFSK signals in Rayleigh fading channels\nYear: 2004\n\nAbstract: In this paper, we provide an analytical performance comparison of various selection combining (SC) schemes for binary noncoherent frequency-shift keying (NCFSK) signals operating on independent and nonidentically distributed (i.n.d.) Rayleigh fading channels. With this motivation, we first derive the receiver structure for the optimum SC scheme, which combines one out of the available diversity branches so as to minimize the probability of bit error. We show that the optimum SC scheme chooses the diversity branch having the largest magnitude of the logarithm of the a posteriori probability ratio (LAPPR) of the transmitted information bit. We also show that: 1) the optimum noncoherent diversity receiver, for binary NCFSK signals, is equivalent to combining the LAPPRs of all the diversity branches; 2) the SC scheme proposed by Neasmith and Beaulieu is a special case of the optimum SC scheme for independent and identically distributed (i.i.d.) Rayleigh fading; and 3) for i.n.d. fading with dual diversity (i.e., ), the performance of the optimum SC scheme is the same as that of the optimum noncoherent diversity receiver, whereas the Neasmith and Beaulieu SC scheme gives the performance of the suboptimum equal gain combining receiver. Bit-error rate (BER) results show that, at BER, for i.i.d. Rayleigh fading, the proposed optimum SC scheme performs better than the existing SC schemes by 0.5-0.9 dB for and by 0.8-1.5 dB for , and performs within 0.3 dB of the optimum noncoherent diversity receiver for , and for i.n.d. Rayleigh fading with , the optimum SC scheme gives an additional gain of about 2.0 dB over the Pierce SC scheme. Further, for i.i.d. Rayleigh fading, we derive the bit-error probability expression for a selection scheme which combines three branches whose LAPPR magnitudes are the largest among the available branches. Numerical results for this selection scheme show that for at a BER of , combining the three branches with the largest LAPPR magnitudes yields almost the full performance of the optimum noncoherent diversity receiver, whereas, for , it is just about 0.2 dB away from the latter. Index Terms—Fading channels, noncoherent frequency-shift keying (NCFSK), optimum combining, selection diversity.","Title: On the capacity of dual diversity combining schemes on correlated Rayleigh fading channels with unequal branch gains\nYear: 2004\n\nAbstract: In this paper, we investigate the effect of fade correlation and the level of imbalance in the mean signal strength on the capacity of Rayleigh fading channels with dual antenna receive diversity. We consider maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SC) diversity schemes and derive expressions for the average and the outage capacities of the channel. For the case of MRC and SC schemes we obtain closed-form expressions for the average and the outage capacities, whereas efficient Gauss-Hermite quadrature rule-based expressions are provided for ECG diversity. Numerical results are provided to illustrate the capacity degradation due to channel correlation and unbalanced diversity branches.","Title: Analysis of selection combining schemes on Rayleigh fading channels with noisy channel estimates\nYear: 2004\n\nAbstract: The optimum selection combining (SC) scheme, proposed recently by Kim, requires estimation of complex channel fades on every diversity channel for minimizing the average probability of error. In this paper, we quantify the effect of imperfect channel estimation on the performance of the optimum SC receiver. By modeling the estimation errors as independent Gaussian random variables, we obtain a simple closed-form expression for the average probability of error. We also analyze a simple sub-optimum SC scheme, based on the output of the coherent matched filter alone, without requiring the knowledge of the fade amplitudes, in the presence of channel estimation errors. Finally, we provide some numerical results to illustrate the comparative performances of various SC receivers with pilot-aided minimum mean-square error (MMSE) channel estimation.","Title: The effects of channel-estimation errors on a space-time spreading CDMA system with dual transmit and dual receive diversity\nYear: 2004\n\nAbstract: The uplink of a space-time spreading code-division multiple-access system with dual transmit and dual receive antennas is analyzed with the effect of imperfect channel estimation. With the help of pilot signals, the Rayleigh multipath fading channel experienced by the transmitted signal is estimated by simple correlators, and subsequently used to coherently combine the multipath signals in a RAKE-like space-time combiner. As a system becomes more wideband, more multipaths are resolved, and the energy in each path is reduced. This reduction in signal strength causes increased estimation error and impacts the system performance. Through the derivation of the probability of error in a space-time spreading system with channel-estimation errors, this paper studies the tradeoff between diversity and estimation errors. It is shown that an optimal bandwidth exists and the optimal power allocation for the pilot signals is a function of the quality of the channel estimates.","Title: Performance of DS/CDMA UWB communication systems in the presence of narrow-band interference and imperfect channel estimation\nYear: 2004\n\nAbstract: This work considers the performance of a DS/CDMA system in the presence of narrow-band interference and imperfect channel estimation. A receiver based on MMSE channel estimation and maximum-likelihood data detection is assumed. An adaptive MMSE receiver, based on the LMS algorithm, is also explored. The performance of the DS/CDMA system is compared with that of a recently proposed UWB spectral-encoded system. The formulation and numerical results presented allow for a better understanding of the spectral overlay effects for UWB communication systems.","Title: Capacities of FDMA/CDMA systems in the presence of phase noise and multipath Rayleigh fading\nYear: 1998\n\nAbstract: The effect of phase noise on the capacities of coher- ently demodulated hybrid frequency-division multiple access/code division multiple-access (FDMA/CDMA) systems operating over a multipath Rayleigh-fading channel is investigated. Using an approximate upper bound on the bit-error rate performance, which has been derived and presented in a previous paper, the capacities of the FDMA/CDMA systems are estimated for several combinations of channel and system parameters. Simulation results are also included to show the effect of the bounding error.","Title: Spectral-Encoded UWB Communication Systems: Real-Time Implementation and Interference Suppression\nYear: 2005\n\nAbstract: This paper considers a particular implementation of an ultra-wideband communication system that uses spectral encoding as both the multiple-access scheme and the interference-suppression technique. The main advantage of this technique is that the transmitted signal spectrum can be conveniently shaped to suppress narrowband interference and to not cause noticeable interference to overlaid systems. An extensive analysis of a possible implementation of this system by using surface acoustic-wave models is presented, and general expressions for the system performance are obtained. Numerical results show that a significant improvement in the system performance is obtained when the proposed interference-suppression method is used.","Title: Optical PPM detection with sample decision photon counting\nYear: 2005\n\nAbstract: A sample-decision photon counting receiver architecture is proposed for use in optical communication systems operating in low-flux conditions such as proposed deep space optical links. The performance of this system using PPM signaling is analyzed and compared to the performance of an ideal photon counter and a slot-energy detection receiver architecture at representative operating points","Title: Throughput-delay analysis of a multichannel wireless access protocol\nYear: 2000\n\nAbstract: In this paper, we analyze the effect of bursty packet losses, caused by a correlation in the multipath fading process, on the throughput and delay performance of a multichannel wireless access protocol. equal-capacity, orthogonal, traffic channels are shared by mobile users on the uplink (mobile-to-base station link). Transmission attempts on the uplink are made based on the busy/idle status of the receivers, which is broadcast by the base station, in every slot, on the downlink (base station-to-mobile link). Following a Markov chain analysis, we derive the analytical expressions for the average per channel throughput and the mean message transfer delay. Simulation results are shown to verify the analysis. We compare the effect of Doppler bandwidth on the performance of both the basic protocol without link layer error recovery and a modified version of the protocol that employs a \"persist-until-success\" link layer retransmission strategy to recover erroneous data packets. any of these channels based on a suitable access protocol. The performance of multichannel slotted ALOHA systems, where multiple equal-capacity channels are shared by many users, has been analyzed in (7) and (8). However, these studies assumed a deterministic channel model that did not consider the effect of multipath fading on the system performance. In fact, mobile radio channels are severely affected by time-varying losses due to distance, shadowing, and multipath fading. While the variation in the losses due to distance and shadowing is relatively slow, the variation due to multipath fading is quite rapid (9), (10). The fading envelope due to multipath typically follows a Rayleigh distribution whose autocorrelation function depends on the normalized Doppler bandwidth, which in turn varies as a function of the mobile user velocity (10). In this paper, we analyze the throughput and delay performance of a multichannel wireless access protocol taking physical layer impairments into account. Specifically, we analyze the effect of bursty packet losses, caused by correlation in the multipath fading process,","Title: Performance of an LMS type receiver for interference suppression in long code DS-CDMA on Rayleigh fading channels\nYear: 2000\n\nAbstract: We consider interference suppression for direct sequence code division multiple access systems when long codes are used for spreading. In particular, we evaluate the performance of a least mean square (LMS) type adaptive receiver on AWGN and correlated Rayleigh fading channels. The receiver uses a chip matched filter followed by an adaptive equalizer structure which performs despreading and interference suppression. The receiver requires only the knowledge of the long code and timing of the desired user. The probability of the error performance of the long code LMS (LC-LMS) receiver is estimated for varying degrees of near-far ratio (NFR), mobile user speed (equivalently, the Doppler bandwidth), and long code period (expressed in number of information bits). Performance results indicate that the given adaptive receiver outperforms the conventional linear correlation receiver by a considerable margin in high NFR and low mobility (i.e., small Doppler bandwidth) scenarios","Title: Beamforming for interference mitigation in TH impulse radio UWB systems\nYear: 2005\n\nAbstract: The ability of impulse radio to resolve a large number of multipaths in a dense frequency selective channel suggests only a marginal improvement in performance by the use of multiple antennas from a diversity perspective. Furthermore, the small size of UWB receivers for in-home or sensor networking would result in a very high correlation among antenna elements, reducing even more the exploitable diversity. Therefore, we concentrate on the use of multiple antennas for interference suppression. Specifically, we investigate the performance of a quadrature receiver for impulse radio systems with multiple receive antennas and minimum-mean-square-error beamforming to combat interference","Title: Bounds on the performance of turbo codes on Nakagami fading channels with diversity combining\nYear: 2001\n\nAbstract: We derive bit error performance bounds for turbo codes on Nakagami fading channels with diversity combining. We first derive the average pairwise error probability expressions for turbo codes with maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) on Nakagami fading channels. Using the pairwise error probability expressions and the union bounding technique, we then obtain bounds on the bit error probability of turbo codes for MRC, EGC, and SC diversity schemes. We present the modified log-MAP turbo decoder for MRC, EGC, and SC, and compare the analytical bounds with simulation results for the special case of 2-antenna diversity with Nakagami parameter m=1 (i.e., Rayleigh fading). Results indicate that the EGC scheme with turbo coding performs close to MRC scheme for i.i.d Rayleigh fading","Title: Acquisition of multicarrier spread spectrum signals with correlated Rayleigh fading among its subcarriers\nYear: 2002\n\nAbstract: Multicarrier (MC) code division multiple access (CDMA) is an attractive way of implementing wideband CDMA systems while being backward-compatible with the existing narrowband CDMA systems. Initial acquisition in MC-CDMA has been studied for the case where the subcarriers experience independent fades. For many of scenarios, the assumption about the independence is unreasonable. We relax this assumption, and employ a realistic model for frequency correlation. We obtain an optimum receiver for initial acquisition that accounts for the frequency correlation, and present a technique for the analysis of this receiver. Finally, we study, by simulation, the tradeoff between the diversity gain available and noncoherent loss incurred as the number of subcarriers is increased.","Title: Statistical channel knowledge-based optimum power allocation for relaying protocols in the high SNR regime\nYear: 2007\n\nAbstract: We are concerned with transmit power optimization in a wireless relay network with various cooperation protocols. With statistical channel knowledge (in the form of knowledge of the fading distribution and the path loss information across all the nodes) at the transmitters and perfect channel state information at the receivers, we derive the optimal power allocation that minimizes high signal-to-noise ratio (SNR) approximations of the outage probability of the mutual information (MI) with amplify-and-forward (AF), decode-and-forward (DF) and distributed space-time coded (DSTC) relaying protocols operating over Rayleigh fading channels. We demonstrate that the high SNR approximation-based outage probability expressions are convex functions of the transmit power vector, and the nature of the optimal power allocation depends on whether or not a direct link between the source and the destination exists. Interestingly, for AF and DF protocols, this allocation depends only on the ratio of mean channel power gains (i.e., the ratio of the source-relay gain to the relay-destination gain), whereas with a DSTC protocol this allocation also depends on the transmission rate when a direct link exists. In addition to the immediate benefits of improved outage behavior, our results show that optimal power allocation brings impressive coding gains over equal power allocation. Furthermore, our analysis reveals that the coding gain gap between the AF and DF protocols can also be reduced by the optimal power allocation.","Title: Decoding on Graphs: LDPC-Coded MISO Systems and Belief Propagation\nYear: 2008\n\nAbstract: This paper proposes a new approach for decoding LDPC codes over MISO channels. Since in an nT times 1 MISO system with a modulation of alphabet size 2M, nT transmitted symbols are combined and produce one received symbol at the receiver, we propose considering the LDPC-coded MISO system as an LDPC code over 2MnT-ary alphabet. Consequently, we propose a modified Tanner graph to introduce belief propagation for decoding MISO-LDPC systems. As a result, the MISO symbol detection and binary LDPC decoding steps are merged into a single message passing decoding. We also propose an efficient method that significantly reduces the complexity of belief propagation decoding in MISO-LDPC systems. Furthermore, we show that our proposed decoder outperforms the conventional decoder for short length LDPC codes in unknown channel scenarios.","Title: Improved Linear Parallel Interference Cancellers\nYear: 2008\n\nAbstract: In this paper, taking the view that a linear parallel interference canceller (LPIC) can be seen as a linear matrix filter, we propose new linear matrix filters that can result in improved bit error performance compared to other LPICs in the literature. The motivation for the proposed filters arises from the possibility of avoiding the generation of certain interference and noise terms in a given stage that would have been present in a conventional LPIC (CLPIC). In the proposed filters, we achieve such avoidance of the generation of interference and noise terms in a given stage by simply making the diagonal elements of a certain matrix in that stage equal to zero. Hence, the proposed filters do not require additional complexity compared to the CLPIC, and they can allow achieving a certain error performance using fewer LPIC stages. We also extend the proposed matrix filter solutions to a multicarrier DS-CDMA system, where we consider two types of receivers. In one receiver (referred to as Type-I receiver), LPIC is performed on each subcarrier first, followed by multicarrier combining (MCC). In the other receiver (called Type-II receiver), MCC is performed first, followed by LPIC. We show that in both Type-I and Type-II receivers, the proposed matrix filters outperform other matrix filters. Also, Type-II receiver performs better than Type-I receiver because of enhanced accuracy of the interference estimates achieved due to frequency diversity offered by MCC.","Title: Optimum transmit-receive beamforming with noisy channel estimates for correlated MIMO Rayleigh channels\nYear: 2008\n\nAbstract: In this paper, we design jointly optimum transmitter and receiver beamforming structures in correlated MIMO Rayleigh fading channels with noisy channel estimates, and evaluate their performance through a closed-form expression for the probability of error. At the receiver, an estimate of the channel is obtained based on the transmitted pilot symbols. The knowledge of the estimate is then made available to the transmitter through a feedback channel. It is assumed that spatial correlation exists, either at the transmitter or at the receiver. A new exact closed-form expression for the probability of error is derived and the joint effects of diversity order and channel estimation accuracy on system performance are analyzed.","Title: Iterative Channel Decoding of FEC-Based Multiple-Description Codes\nYear: 2012\n\nAbstract: Multiple description coding has been receiving attention as a robust transmission framework for multimedia services. This paper studies the iterative decoding of FEC-based multiple description codes. The proposed decoding algorithms take advantage of the error detection capability of Reed-Solomon (RS) erasure codes. The information of correctly decoded RS codewords is exploited to enhance the error correction capability of the Viterbi algorithm at the next iteration of decoding. In the proposed algorithm, an intradescription interleaver is synergistically combined with the iterative decoder. The interleaver does not affect the performance of noniterative decoding but greatly enhances the performance when the system is iteratively decoded. We also address the optimal allocation of RS parity symbols for unequal error protection. For the optimal allocation in iterative decoding, we derive mathematical equations from which the probability distributions of description erasures can be generated in a simple way. The performance of the algorithm is evaluated over an orthogonal frequency-division multiplexing system. The results show that the performance of the multiple description codes is significantly enhanced.","Title: Channel Model and Performance Analysis of QAM Multiple Antenna Systems at 60-GHz in the Presence of Human Activity\nYear: 2011\n\nAbstract: In this paper, a 60-GHz channel model that incorporates the presence of human activity, and which is an extension of the standard channel model proposed by the IEEE 802.15.3c group, is presented. In the presence of human activity, various measurement results show that the attenuation due to human blockage can be 20 dB or more, and thus is non-negligible. Various measurement results in the literature are used to determine the distribution of the shadowing attenuation caused by human blockage. A multiuser single-carrier system with a single receiver is considered, and system performance in the presence of blockage because of human activity is evaluated. Numerical results show that the 60-GHz system can incur a large degradation in bit error rate due to human blockage.","Title: Progressive Source Transmissions Using Joint Source-Channel Coding and Hierarchical Modulation in Packetized Networks\nYear: 2009\n\nAbstract: With Unequal Error Protection (UEP), more important symbols are given greater protection against channel errors than are less important symbols. The protection can be accomplished by various methods, including joint source-channel coding (JSCC) and hierarchical modulation. In this paper, a robust progressive source transmission system using forward error correction (FEC) and a bits-to-symbol assignment methodology that provides UEP is proposed. UEP is not only provided by hierarchical modulation but also by the packetization methodology combined with channel coding. It is demonstrated by simulation that our system improves performance compared to an Equal Error Protection (EEP) technique and to a baseline JSCC-only mechanism.","Title: Variance-Aware Adaptive Modulation for OFDM-Based Multiple Description Progressive Image Transmission\nYear: 2010\n\nAbstract: Average throughput maximization has commonly been used as an alternative to image or video average distortion minimization. However, as the throughput-distortion curve is non-linear, throughput maximization can be very different from distortion minimization if the variance of the throughput is large. Under high channel quality variability, the variance of the throughput will be high. Multiple description coding with unequal error protection is a promising technique for the transmission of progressive images when there exists a high variability of the channel conditions. In this paper, we consider both the variance and the average of the throughput when deciding the constellation size for adaptive modulation in an OFDM system used for transmitting progressively-coded images with multiple description coding. Simulation results show that in an adaptive modulated image transmission system, taking into account both moments of the throughput achieves better performance than a system considering average throughput alone.","Title: Subcarrier mapping based on slice visibility for video transmission over OFDM channels\nYear: 2012\n\nAbstract: We address channel code rate optimization for transmission of non-scalable coded video sequences over orthogonal frequency division multiplexing networks for scenarios with arbitrary mobility. A slice loss visibility (SLV) model is used to evaluate the visual importance of each H.264 slice. In particular, taking into account both the visibility scores available from the bitstream and the channel state information, we optimize the channel code rate for each GOP and the mapping of video slices within 2-D time-frequency resource blocks, in order to better protect more visually important slices. Results demonstrate that the proposed algorithm outperforms baseline ones which do not take into account the SLV in the video transmission.","Title: Optimized receiver design for decode-and-forward relays using hierarchical modulation\nYear: 2013\n\nAbstract: We consider a wireless relay network with a single source, a single destination, and multiple relays. The relays are half-duplex and use the decode-and-forward protocol. The transmit source is a layered bitstream, which can be partitioned into two layers. The source broadcasts both layers to all the relays and the destination using hierarchical 16-QAM. Each relay detects and transmits successfully decoded layers to the destination using either hierarchical 16-QAM or QPSK using orthogonal channels. We derive the optimal linear-combining receiver at the destination, where the uncoded bit error rate is minimized. We also present a suboptimal combining method with a closed-form solution, which performs very close to the optimal. Numerical results show that the two-layer scheme outperforms the classical one-layer scheme using conventional modulation.","Title: Coded Hierarchical Modulation for Wireless Progressive Image Transmission\nYear: 2011\n\nAbstract: A robust coded scheme for progressive multimedia transmission is proposed for additive white Gaussian noise, flat Rayleigh fading channels, and frequency-selective channels using different unequal error protection methods in combination. Hierarchical modulation is coupled with a packetization/combining strategy and an efficient channel encoder consisting of a cyclic redundancy check outer coder concatenated with an inner rate-compatible punctured convolutional coder. Distortion-optimal hierarchical parameters are jointly chosen with the set of channel coding parameters on a packet-switched wireless network with fixed length packets. A lower bound for the performance improvement of the proposed system is derived and shown to give significant gains at lower packet sizes and higher transmission rates. The proposed system is also shown to outperform several existing schemes for realistic wireless channels.","Title: Error Rate for PSK and QAM Modulations for Non-Ideal OFDM Systems with Noisy Channel Estimates and Receive Diversity\nYear: 2011\n\nAbstract: This paper characterizes the SER for a non-ideal OFDM system with either M-PSK or M-QAM constellations operating over a frequency-selective, time-varying, Rayleigh fading channel. The imperfections that we consider are inter-carrier interference (ICI) and/or inter-symbol interference (ISI), imperfect time and frequency synchronization, and noisy channel estimates. We consider an MRC receiver with L diversity branches. We present SER characterizations with and without ISI, and show that the effect of ISI, especially for higher order modulation schemes, e.g., 8PSK and above, can be very severe, irrespective of the number of diversity branches.","Title: Channel estimation for non-ideal OFDM systems\nYear: 2010\n\nAbstract: Studies of channel estimation techniques for OFDM systems often assume idealized conditions such as a cyclic prefix (CP) long enough to absorb the entire channel delay spread, or perfect time and frequency synchronization at the receiver. This paper studies the impact of removing these assumptions. We characterize the mean square error (MSE) of various linear channel estimation methods, and we derive analytical expressions for the BER performance. The derivations are kept generic so that they apply to both time-division and frequency-division multiplexing of the pilot signal and the data subcarriers. The analysis is specialized to the BER performance characterization of OFDM-based UWB systems for different realistic channel estimation methods with residual time and frequency errors. The effect of inter-carrier interference (ICI) on channel estimation is shown to be small. However, inter-symbol interference (ISI) severely impacts the quality of the channel estimates and hence can yield a large (>2 dB) data demodulation performance degradation.","Title: Optimal Multiplexed Hierarchical Modulation for Unequal Error Protection of Progressive Bit Streams\nYear: 2009\n\nAbstract: Progressive image and scalable video have gradual differences of importance in their bitstreams, which can benefit from multiple levels of unequal error protection (UEP). Though hierarchical modulation has been intensively studied as an UEP approach for digital broadcasting and multimedia transmission, methods of achieving a large number of UEP levels have rarely been studied. In this paper, we propose a multilevel UEP system using multiplexed hierarchical quadrature amplitude modulation (QAM) for progressive transmission over mobile radio channels. We suggest a specific way of multiplexing, and prove that multiple levels of UEP are achieved by the suggested method. When the BER is dominated by the minimum Euclidian distance, we derive an optimal multiplexing approach which minimizes both the average and peak powers. An asymmetric hierarchical QAM which reduces the peak-to-average power ratio (PAPR) without performance loss is also proposed. Numerical results show that the performance of progressive transmission over Rayleigh fading channels is significantly enhanced by the proposed UEP systems.","Title: Optimization of generalized LT codes for progressive image transfer\nYear: 2012\n\nAbstract: Rateless codes allow a user to incrementally send additional redundancy, so they can be useful for heterogeneous and time-varying networks for which the choice of redundancy level in advance is difficult. Rateless codes are an attractive application layer forward error correction solution due to their flexibility and capacity-approaching performance. The original rateless codes were developed for the delivery of equally important information. In many multimedia applications, some data symbols are more important than others. Unequal error protection (UEP) designs are attractive solutions for such transmissions. However previous UEP rateless code designs were aimed for coarsely layered sources and might exhibit poor performance for fine-grained progressive coding. The main objective of this paper is to introduce a more generalized coding scheme, parameters of which can be tailored for progressive multimedia transmission. We present the optimization of a generalized rateless code using two different progressive source transmission protocols. Proposed coding scheme is shown to exhibit better unequal protection and recovery time properties than other published results.","Title: Throughput and Delay Analysis for Real-Time Applications in Ad-Hoc Cognitive Networks\nYear: 2010\n\nAbstract: We consider a simple ad-hoc cognitive scenario with two data up-links, one licensed to use the spectral resource (primary) and the other unlicensed (secondary or cognitive). It is assumed that the cognitive link accesses the channel only when the channel is sensed idle. An ON-OFF channel model is used for the primary link, where traffic statistical characteristics are taken into account. A closed-form expression for the signal-to noise-plus interference (SINR) statistics of the cognitive nodes is derived that can be used for estimating the network performance. Moreover, a M/G/1 queueing model is exploited for deriving a simple expression for the average packet delay. Finally, a MAC strategy based on a channel-and-queue aware scheduling is introduced.","Title: Joint source-channel coding of 3D video using multiview coding\nYear: 2013\n\nAbstract: We consider the joint source-channel coding problem of a 3D video transmitted over an AWGN channel. The goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under two constraints: the quality of the primary view and the quality of the secondary view must be greater than or equal to a predetermined threshold at the receiver. The quality is measured in terms of the expected PSNR of an entire decoded group of pictures. A MVC (multiview coding) encoder is used as the source encoder, and rate compatible punctured turbo codes are utilized for protection of the encoded 3D video over the noisy channel. Equal error protection and unequal error protection are compared for various 3D video sequences and noise levels.","Title: Device-To-Device Assisted Video Transmission\nYear: 2013\n\nAbstract: To increase spectrum efficiency, researchers envision a device-to-device (D2D) communication system in which a closely located mobile device pair may share the same spectrum with a cellular user. By opportunistically choosing the frequency, the D2D pair may increase the spectrum efficiency in terms of data rate per Hertz, at the price of additional interference to that cellular user. In previous models, users either stop cellular transmission and switch to D2D transmission or vice versa. However, if the cell is fully loaded, a D2D pair will not be able to switch back to the conventional mode because no extra resource is available. In this paper, we propose a D2D assisted model, where a D2D link is enabled to assist transmission, while keeping the conventional cellular transmission. In this way, the D2D link can be turned on and off according to the link quality. We also propose a PHY-layer study for the transmission scheme in such a way that the system throughput and the video reception quality is always improved compared to a conventional link.","Title: Video cognitive radio networks for tactical scenarios.\nYear: 2016\n\nAbstract: We examine the performance of uplink video transmission over a mobile cognitive radio (CR) system operating in a hostile environment where an intelligent adversary tries to disrupt communications. We investigate the optimal strategy for spoojing, desynchronizing and jamming a cluster-based CR network with a Gaussian noise signal, over a Rayleigh fading channel. The adversary can limit access for secondary users (SUs) by either transmitting a spoojing signal in the sensing interval, or a desynchronizing signal to disrupt code acquisition by SUs or the cluster head. By jamming the network during the transmission interval, the adversary can reduce the rate of successful transmission. We also propose cross-layer resource allocation algorithms and evaluate their performance under disruptive attacks.","Title: Resource Allocation for Multicarrier D2D Video Transmission Based on Exact Symbol Error Rate.\nYear: 2016\n\nAbstract: We consider centralized cross-layer resource allocation for a device-to-device (D2D) video transmission system, given knowledge of the channel state information and the rate distortion information of the video streams, and propose an iterative algorithm for subcarrier assignment and power allocation. In the resource allocation, the performance improvement by applying the exact symbol error rate (SER) is compared with the conventional signal-to-interference-plus-noise-ratio (SINR) based SER evaluation method that uses a Gaussian approximation (GA) for the aggregated interference. An exact SER expression for a D2D system using multicarrier bandlimited QAM is derived and then used in the resource allocation algorithm. Bit-level simulations for different numbers of D2D pairs demonstrate a considerable improvement on user capacity and video peak signal-to-noise ratio by incorporating the proposed SER expression compared to the GA.","Title: Optimization of Scalable Broadcast for a Large Number of Antennas.\nYear: 2017\n\nAbstract: In this paper, for a system incorporating a large number of antennas, we address the optimal space-time coding of multimedia scalable sources, which require unequal target error rates in their bitstream. First, in terms of the number of antennas, we analyze the behavior of the crossover point of the outage probability curves for the vertical Bell Laboratories space-time (V-BLAST) architecture with...","Title: Spatially Scalable Video Broadcasting In Multiple Antenna Systems\nYear: 2016\n\nAbstract: We propose an efficient multiple-input multipleoutput (MIMO) video broadcasting technique with low computational complexity that well serves different types of users residing inside the service area of a base station. We consider a video broadcasting scenario in which heterogeneous users with different display resolutions, different operating bit rates, and different numbers of receive antennas are present. Our proposed scheme adopts spatially scalable video coding, and makes use of both spatial diversity and spatial multiplexing techniques. We compare the performance of our proposed scheme with that of a non-scalable video transmission scheme. Simulation results show that our proposed video broadcasting scheme significantly outperforms the non-scalable video broadcasting strategy. The performance improvement is observed for both different types of users we consider.","Title: Subcarrier Assignment and Power Allocation for Device-to-Device Video Transmission in Rayleigh Fading Channels.\nYear: 2017\n\nAbstract: Subcarrier assignment and power allocation for device-to-device (D2D) video transmission using a filter bank multicarrier waveform in a Rayleigh fading environment are investigated. We analyze the co-channel interference between D2D pairs, and propose a cross-layer algorithm with a subcarrier assignment outer loop and a power allocation inner loop, which aims to optimize the overall video quality....","Title: Sensing Disruption with Estimation Uncertainty.\nYear: 2017\n\nAbstract: In this paper, the sensing disruption for a power limited adversary with estimation uncertainty is formulated and analyzed. The estimation uncertainty of the adversary is modeled in terms of its probability of false alarm in vacant bands and the probability of detection in busy bands. The strategy for the adversary is obtained by maximizing the sum of the conditional probabilities of false detection within the spectral range of interest, conditioned on the adversary's estimated spectrum usage status. The proposed algorithm is shown to be significantly more robust than conventional algorithms. It is shown in simulation results that, as the adversary's power budget increases, the proposed algorithm asymptotically approaches the performance upper bound when the adversary has perfect information on the spectrum usage status.","Title: Delay allocation between source buffering and interleaving for wireless video.\nYear: 2016\n\nAbstract: One fundamental tradeoff in the cross-layer design of a communications system is delay allocation. We study delay budget partitioning in a wireless multimedia system between two of the main components of delay: the queuing delay in the source encoder output buffer and the delay caused by the interleaver. In particular, we discuss how to apportion the fixed delay budget between the source encoder and the interleaver given the channel characteristics, the video motion, the delay constraint, and the channel bit rate.","Title: Cross-Layer Resource Allocation Using Video Slice Header Information for Wireless Transmission Over LTE.\nYear: 2018\n\nAbstract: In this paper, cross-layer resource allocation methods for wireless video transmission are proposed. We propose two practical metrics to measure the relative importance of each forward error correction (FEC) block to the user's quality of experience. They can be obtained from the header information, and require no overhead bits or amendment of the header format of the existing standard video codec...","Title: Optimal Sensing Disruption: A Generalized Framework for a Power-Limited Adversary\nYear: 2019\n\nAbstract: A generalized framework of spectrum sensing disruption for a power-limited adversary is proposed in this paper. In the literature, a conventional sensing attack typically assumes that the adversary has perfect knowledge of the spectral usage status. The framework in this paper considers a more general case where there are uncertainties in the estimates at the adversary. These uncertainties are modeled utilizing the probability of detection and the probability of false alarm. Then, the sum of the conditional probabilities of false detection at the secondary within the spectral range of interest, conditioned on the adversary’s estimated spectrum usage status, is maximized. It is shown that the optimal sensing attack, given perfect estimation is a special case of the proposed framework. When the adversary has perfect spectrum usage information, this framework reduces to a previously demonstrated optimal sensing disruption. When the adversary has imperfect information on the spectral status, the proposed framework is significantly more robust than conventional sensing attacks. Further, when the adversary’s power budget increases, it asymptotically approaches the sensing disruption performance upper bound.","Title: Robustness of Deep Modulation Recognition under AWGN and Rician Fading\nYear: 2018\n\nAbstract: We study the robustness of modulation recognition using deep neural networks. This is of critical importance for applying deep learning for radio modulation classification, because wireless propagation conditions could vary significantly under different communication environments. We compare the performance of radio modulation recognition using data and using expert features. While deep modulation recognition using data has been proposed in existing literature since it achieves better performance than crafted expert features, our results indicate that using expert features yields significantly more robustness.","Title: Joint Channel Estimation and Error Correction for Finite-State Markov Channels Using Polar Codes.\nYear: 2018\n\nAbstract: A joint channel estimation and channel coding scheme is presented for finite-state Markov channels using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding algorithm and computes decoding metrics averaged over the statistical behavior of the Markov channel. By adapting list decoding (without any inner code), channel estimation and decoding steps can be performed iteratively to boost the reliability of channel estimation as well as error correction. In order to improve the performance even further, a new pilot transmission scheme is developed that utilizes the structure of polar codes and sends pilot symbols along with code symbols. This construction can be viewed as a new family of shortened polar codes that can be of independent interest. Simulation results demonstrate the benefit of the proposed approach compared to existing solutions.","Title: Performance analysis of TCM with generalized selection combining on Rayleigh fading channels.\nYear: 2002\n\nAbstract: We derive the computational cutoff rate, R/sub 0/, for coherent trellis-coded modulation (TCM) schemes on independent identically distributed (i.i.d.) Rayleigh fading channels with (K, L) generalized selection combining (GSC) diversity, which combines the K paths with the largest instantaneous signal-to-noise ratios (SNR) among the L available diversity paths. The cutoff rate is shown to be a simple function of the moment generating function (MGF) of the SNR at the output of the (K, L) GSC receiver. We also derive the union bound on the bit error probability of TCM schemes with (K, L) GSC in the form of a simple, finite integral. The effectiveness of this bound is verified through simulations.","Title: Joint Partial-Time Partial-Band Jamming of a Multicarrier DS-CDMA System in a Fading Environment.\nYear: 2018\n\nAbstract: The impact of joint partial-band, partial-time jamming on a multi-carrier asynchronous DS-CDMA system in a Rayleigh fading environment is studied. Two types of partial-time jamming are studied: equal probability jamming per symbol, and burst jamming. An easy to evaluate upper bound using the Chernoff bound is provided and compared to simulation results.","Title: Resource Allocation for Multicarrier Device-to-Device Video Transmission: Symbol Error Rate Analysis and Algorithm Design.\nYear: 2017\n\nAbstract: In resource allocation for a device-to-device (D2D) video transmission system, the performance improvement by applying the exact symbol error rate (SER) is compared with the conventional signal-to-interference-plus-noise-ratio-based SER evaluation method that uses a Gaussian approximation (GA) for the aggregated interference. An analytical SER expression for a D2D system using multicarrier bandlim...","Title: Joint Channel Estimation and Coding Over Channels With Memory Using Polar Codes\nYear: 2021\n\nAbstract: A joint channel estimation and channel coding scheme is presented for channels with memory using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding procedure and computes decoding metrics averaged over the sta..."],"string":"[\n \"Title: Performance Analysis Of Generalized Selection Combining Of M-Ary Ncfsk Signals In Rayleigh Fading Channels\\nYear: 2003\\n\\nAbstract: In this paper, we propose and analyze the bit error performance of a generalized selection combining (GSC) receiver for M-ary noncoherent frequency shift keying (NCFSK) signals on i.i.d. Rayleigh fading channels with L antennas at the receiver. For each of the M hypotheses, the receiver combines the K largest outputs among the L available square-law detector outputs before proceeding to the bit detection process. We derive a closed-form expression for the bit error probability of the proposed (K, L) GSC receiver, and present numerical results to illustrate the bit error performance of this receiver for different values of M, K, and L. We also show that our generalized (K, L) GSC scheme and analysis encompass the previously reported schemes/analyses by Chyi et al and Hahn as special cases for K = 1 and K = L, respectively.\",\n \"Title: Optimal allocation of bandwidth for source coding, channel coding, and spreading in CDMA systems\\nYear: 2004\\n\\nAbstract: This paper investigates the tradeoffs between source coding, channel coding, and spreading in code-division multiple-access systems, operating under a fixed total bandwidth constraint. We consider two systems, each consisting of a uniform source with a uniform quantizer, a channel coder, an interleaver, and a direct-sequence spreading module. System A is quadrature phase-shift keyed modulated and ...\",\n \"Title: Effects of imperfections on the performance of OFDM systems\\nYear: 2009\\n\\nAbstract: Most OFDM analyses assume idealized conditions when it comes to the waveform at the receiver in terms of time and frequency synchronization. In addition, often a cyclic prefix (CP) longer than the channel delay spread is assumed, and thus the impact of the possible inter-symbol interference (ISI) from adjacent OFDM symbols is not a consideration. This work provides a consolidated framework for study and analysis of OFDM systems with imperfections. The imperfections include time and frequency synchronization errors, and channel delay spread beyond the CP duration. Transmit as well as receive filtering operations are explicitly modeled, and different receiver detection criteria are considered. The use of an OFDM waveform for UWB applications is known to be a promising choice to simplify the receiver design and to maximize the bandwidth scalability, as well as the adaptation to various spectrum allocations. We present bit error rate (BER) sensitivity analysis to key system parameters for OFDM-based UWB applications. From these sensitivity analyses, we see graceful performance degradation with decreasing CP length and increasing residual frequency error. The performance degradation can be much more critical for timing synchronization errors.\",\n \"Title: Motion-Compensated Scalable Video Transmission over MIMO Wireless Channels under Imperfect Channel Estimation\\nYear: 2009\\n\\nAbstract: We study motion compensated fine granular scalable (MC-FGS) video transmission over multi-input multi-output (MIMO) wireless channels, where leaky and partial prediction schemes are applied in the enhancement layer of MC-FGS to exploit the tradeoff between error propagation and coding efficiency. For reliable transmission, we propose unequal error protection (UEP) by considering a tradeoff between reliability and data rates, which are controlled by forward error correction (FEC) and MIMO mode selection to minimize the average distortion. In a high Doppler environment where it is hard to get an accurate channel estimate, we investigate the performance of the proposed MC-FGS video transmission scheme with joint control of the leaky and partial prediction parameters and the UEP.\",\n \"Title: Unequal error protection based on slice visibility for transmission of compressed video over OFDM channels\\nYear: 2011\\n\\nAbstract: We address channel code rate optimization for transmission of non-scalable coded video sequences over orthogonal frequency division multiplexing networks. A slice loss visibility (SLV) model is used to evaluate the visual importance of each H.264 slice. Based on both the SLV model and the frequency diversity order available from the channel, we propose a cross-layer technique to allocate video slices within a 2-D time-frequency resource block, and optimize the unequal channel code rate profile, in order to better protect more visually important slices. The proposed algorithm outperforms baseline ones which do not take into account the SLV.\",\n \"Title: Hybrid pulse position modulation/ultrashort light pulse code-division multiple-access systems .I. Fundamental analysis.\\nYear: 2002\\n\\nAbstract: We propose a hybrid pulse position modulation/ultrashort light pulse code-division multiple-access (PPM/ULP-CDMA) system for ultrafast optical communications. The proposed system employs spectral CDMA encoding/decoding and PPM with very short pulse separation. The statistical properties of the encoded ULP are investigated with a general pulse model, and the performance of the proposed PPM/ULP-CDMA...\",\n \"Title: Generalized unequal error protection LT codes for progressive data transmission.\\nYear: 2012\\n\\nAbstract: The original design of standard digital fountain codes assumes that the coded information symbols are equally important. In many applications, some source symbols are more important than others, and they must be recovered prior to the rest. Unequal Error Protection (UEP) designs are attractive solutions for such source transmissions. In this study, we introduce a more generalized design for the first universal fountain code design, LT codes, that makes it particularly suited for progressive bit stream transmissions. We apply the generalized LT codes to a progressive source and show that it has better UEP properties than other published results in the literature. For example, using the proposed generalization, we obtained up to 1.7dB PSNR gain in a progressive image transmission scenario over the two major UEP fountain code designs.\",\n \"Title: Power Control on the Forward Link in Cellular CDMA\\nYear: 1994\\n\\nAbstract: In this paper, a CDMA cellular system is considered. An analysis of the performance is presented for the base-to-mobile link, along with a method to optimize the power control law. The performance of the system is evaluated in terms of both probability of error and system utilization (i.e., the number of admitted users per cell divided by the spreading factor). A comparison with some results which recently have appeared in the literature is also presented.\",\n \"Title: An RF Receiver Detection Technique for Cognitive Radio Coexistence\\nYear: 2010\\n\\nAbstract: A receiver detection technique is proposed by measuring the low-level leakage signal from a nearby receiver local oscillator. The probabilities of false alarm and missed detection are derived to quantify the detection performance. The technique provides higher sensitivity than a radiometer and is robust to estimation error even if the power spectral density of the ambient noise is unknown.\",\n \"Title: The performance of a space-time spreading CDMA system with channel estimation errors.\\nYear: 2002\\n\\nAbstract: Transmit diversity has been studied recently as an effective technique to provide high-performance wireless transmission. Space-time spreading is a transmit diversity scheme that achieves full spatial diversity while maintaining high spectral efficiency. This paper analyzes how channel estimation errors in diversity combining affects the uplink of a space-time spreading CDMA system with two transmit and two receive antennas. Pilot and data from K asynchronous users are transmitted through a Rayleigh multipath fading channel. The channel estimates are obtained at the outputs of correlators, and are used in the RAKE combiner. As a system becomes more wideband, more multipaths are resolved, and the energy in each path is reduced. This reduction in signal strength causes Increased estimation error and impacts the system performance. This paper studies the tradeoff between diversity and estimation errors.\",\n \"Title: Performance of a wireless access protocol on correlated Rayleigh-fading channels with capture\\nYear: 1998\\n\\nAbstract: The throughput performance of a wireless media access protocol taking into account the effect of correlated channel fading, capture, and propagation delay is analyzed. For efficient access on the uplink (mobile-to-base-station link), the protocol makes use of the uplink channel status information which is conveyed to the mobiles through a busy/idle flag broadcast on the downlink (base-station-to-m...\",\n \"Title: The Impact of Nonlinear Amplification on Multi-Code CDMA Systems\\nYear: 2000\\n\\nAbstract: This paper investigates the behavior of multi-code DS/CDMA systems in the presence of nonlinear distortions caused by high pourer amplifiers. A technique that uses a small number of parallel transmitted sequences is proposed for combating the nonlinearity. This technique can be modified to have a constant envelope for achieving further performance improvement. It is seen from performance comparisons that the proposed scheme is very effective for combating the nonlinearity.\",\n \"Title: Analysis of hybrid, coherent FDMA/CDMA systems in Ricean multipath fading\\nYear: 1997\\n\\nAbstract: This paper extends the analysis presented by Eng and Milstein (see IEEE J. Select. Areas Commun., vol.12, no.5, p.938-951, 1994) of a hybrid frequency division multiple access/code-division multiple-access [FDMA/CDMA (F/CDMA)] system in a Rayleigh fading environment to include the presence of a direct-path component (i.e., Ricean fading). The results show that a "wideband" CDMA system out performs...\",\n \"Title: Video coding with fixed-length packetization for a tandem channel.\\nYear: 2006\\n\\nAbstract: A robust scheme is presented for the efficient transmission of packet video over a tandem wireless Internet channel. This channel is assumed to have bit errors (due to noise and fading on the wireless portion of the channel) and packet erasures (due to congestion on the wired portion). First, we propose an algorithm to optimally switch between intracoding and intercoding for a video coder that operates on a packet-switched network with fixed-length packets. Different re-synchronization schemes are considered and compared. This optimal mode selection algorithm is integrated with an efficient channel encoder, a cyclic redundancy check outer coder concatenated with an inner rate-compatible punctured convolutional coder. The system performance is both analyzed and simulated. Last, the framework is extended to operate on a time-varying wireless Internet channel with feedback information from the receiver. Both instantaneous feedback and delayed feedback are evaluated, and an improved method of refined distortion estimation for encoding is presented and simulated for the case of delayed feedback.\",\n \"Title: Exploiting multiuser diversity for fair scheduling in MIMO downlink networks with imperfect channel state information\\nYear: 2009\\n\\nAbstract: In this paper, we consider a time-slotted MIMO point-to-multipoint network, which, for example, could represent either a cellular downlink, or a cluster in a wireless mesh network. The transmitter sends an independent data stream from each transmit antenna to communicate simultaneously to a subset of the receivers in each slot. The transmitter sends training symbols at the beginning of each slot so that each receiver can estimate the channel and determine the data rate it could potentially receive from each transmit antenna after configuring its antenna weights appropriately. For this purpose, we develop a maximum-likelihood estimator of the signal to interference plus noise ratio (SINR) from the received training symbols. The transmitter decides which receivers to serve in each slot to maximize the minimum normalized average data rate realized by each receiver. This scheduling decision is made based on estimated SINR information fed back by receivers. Through some numerical examples, we discuss some general issues with regard to exploitation of multi-user diversity in the context of imperfect channel state information. For example, the scheduler introduces a bias for positive SINR estimation errors, which is important to take into account when the receivers declare a potential data rate in each slot.\",\n \"Title: Parallel acquisition in mobile DS-CDMA systems\\nYear: 1997\\n\\nAbstract: This paper presents the performance of a direct sequence spread spectrum acquisition scheme in a mobile terrestrial communications system. The effects of fading, multipath, power control, shadowing, multiple access interference, out-of-cell interference, vehicle speed, voice activity, and sectorization are examined. The acquisition scheme uses noncoherent detection and a parallel search strategy. The analysis is done for the reverse link of a mobile code-division multiple-access (CDMA) system. The purpose of this paper is to derive the acquisition performance of a mobile communications system under practical assumptions, and give realistic capacity estimates based on acquisition performance criteria\",\n \"Title: Error Rate of a Multicarrier CDMA System with Imperfect Channel Estimates\\nYear: 2000\\n\\nAbstract: Bit error rate is evaluated for a multicarrier CDMA system with channel estimation errors. We consider a multicarrier CDMA system with pilot and data channels. The signal experiences independent flat Rayleigh fading on each subcarrier. Simple integrators produce the channel estimates which are used to maximal-ratio-combine the data from all the subcarriers, Keeping the total transmitted energy fixed, as the number of subcarriers increases, the weaker signal in each subcarrier makes channel estimation more difficult and results in larger errors in the combiner weights. We quantify how errors in channel estimation affect a multicarrier CDMA system as the system becomes more wideband. We will show that there is a tradeoff between diversity order and SNR available for channel estimation.\",\n \"Title: Average SNR of a generalized diversity selection combining scheme\\nYear: 1999\\n\\nAbstract: The average signal-to-noise ratio (SNR) of a gen- eralized selection combining scheme, in which the diversity branches ( , where is the total number of diversity branches available) with the largest instantaneous SNR's are selected and coherently combined, is derived. A Rayleigh fading channel is assumed, and a simple closed-form expression for the SNR is found which is upper bounded by the average SNR of maximal ratio combining, and lower bounded by average SNR of conventional selection combining. IVERSITY combining has been considered as an ef- ficient way to combat multipath fading because the combined signal-to-noise ratio (SNR) is increased compared with the SNR of each diversity branch. The optimum combiner is the maximal ratio combiner (MRC) whose SNR is the sum of the SNR's of each individual diversity branch. The conventional selection combiner (CSC) selects the signal from that diversity branch with the largest instantaneous SNR. In this paper, we study a generalized selection scheme. Instead of selecting only the largest (in instantaneous SNR) diversity signal as in CSC, we choose the largest signals from total diversity branches and then coherently combine them. The average SNR of this GSC is derived and a simple closed-form expression is found, which is upper bounded by the average SNR of MRC and lower bounded by the average SNR of CSC, as expected.\",\n \"Title: Open-loop power control performance in DS-CDMA networks with frequency selective fading and non-stationary base stations\\nYear: 1998\\n\\nAbstract: In this paper, we study the performance of a simple and easy-to-implement distributed power control strategy applicable to direct sequence code division multiple access (DS-CDMA) networks. The scheme makes use of the received power measurements made on the forward link at individual mobile units to control the transmit powers on their reverse links. The algorithm, which effectively compensates for the slowly varying distance and shadow losses (due to their high correlation on both forward and reverse links), attempts to minimize the effect of fast multipath fading by averaging it out. We adopt a quasi-analytic approach to estimate the reverse link capacity performance of an open-loop power control scheme in both a single cell and a multi-cell environment, and we do this for both a fixed base station and a moving base station scenario. Non-stationary base stations are typical in tactical and emergency communications scenarios where the base stations could be mounted on moving platforms (e.g., tanks, jeeps, unmanned airborne vehicles). We estimate the capacity degradation, when base stations move relative to other cells, as a function of the amount of cell overlap and the standard deviation of the power control error. We also provide a comparison of the performance of the open-loop power control strategy with that of a closed-loop power control strategy.\",\n \"Title: Performance of Multiple Antenna DS-CDMA UWB System With Noisy Channel Estimates and Narrow-Band Interference\\nYear: 2007\\n\\nAbstract: In this work, the performance of a DS-CDMA ultra-wideband (UWB) system with multiple antennas at the receiver, in the presence of multiple users and narrow-band interference (NBI), is evaluated. A spatio-temporal UWB receiver is proposed which first forms an estimate of the channel in the presence of multi-access interference and NBI, and then uses this estimate to optimally combine the multipath ...\",\n \"Title: First-Order Markov Models For Packet Transmission On Rayleigh Fading Channels With Dpsk/Ncfsk Modulation\\nYear: 2006\\n\\nAbstract: In this paper, we develop first-order Markov mod- els that characterize the packet error processes on Rayleigh fading channels considering binary DPSK/NCFSK modulation. Such models available in the literature so far consider only the fading process ignoring the underlying modulation used. Our contribution in this paper is that we consider first-order Markov models for binary DPSK/NCFSK modulation. To derive the Markov model parameters, we first derive expressions for the second-order statistics of the channel error process (specifically, the auto-correlation function of the bit error process as well as the packet error process), and obtain the Markov model parameters, in closed-form, as a function of normalized Doppler bandwidth, average received SNR and packet length. We also verify the accuracy of the proposed Markov model by deriving closed-form expressions for the mutual information of the channel error process.\",\n \"Title: Performance analysis of coded communication systems on Nakagami fading channels with selection combining diversity\\nYear: 2004\\n\\nAbstract: In this paper, we develop analytical tools for the performance analysis of coded, coherent communication systems on independent and identically distributed Nakagami-m fading channels with selection combining (SC) diversity. First, we derive an exact expression for the moment generation function (MGF) of the signal-to-noise ratio (SNR) of a code symbol at the output of the selection combiner. Next,...\",\n \"Title: The performance of a direct-sequence spread-spectrum acquisition system using a linear prediction filter for narrowband interference suppression\\nYear: 1996\\n\\nAbstract: The coarse acquisition performance of a direct sequence spread-spectrum receiver is analyzed when a linear prediction filter is used for narrowband interference suppression. We show that once an appropriate matching strategy is identified, the linear prediction filter can provide favorable performance when narrowband interference is present over a considerable range of both interference power and bandwidth. In addition, the presence of the filter dramatically improves the performance over the case where there is no filter, except when the interference bandwidth and the power are both small (i.e., when the processing gain provides sufficient interference immunity without the filter). If long spreading sequences are used with moderately sized observation windows, the acquisition performance can be severely degraded when a parallel acquisition scheme is used due to the linear predication filter. We show, however, that a slower serial receiver will provide reliable performance.\",\n \"Title: Multicode Mimo For High Data Rate Mobile Ad-Hoc Networks\\nYear: 2006\\n\\nAbstract: In a mobile ad-hoc network scenario, where communication nodes are mounted on moving platforms (like jeeps, trucks, tanks, etc.), use of V-BLAST requires that the number of receive antennas in a given node must be greater than or equal to the sum of the number of transmit antennas of all its neighbor nodes. This limits the achievable spatial multiplexing gain (data rate) for a given node. In such a scenario, we propose to achieve high data rates per node through multicode direct sequence spread spectrum techniques in conjunction with V-BLAST. In the considered multicode V-BLAST system, the receiver experiences code domain interference (CDI) in frequency selective fading, in addition to space domain interference (SDI) experienced in conventional V-BLAST systems. We propose two interference cancelling receivers that employ a linear parallel interference cancellation approach to handle the CDI, followed by conventional V-BLAST detector to handle the SDI, and then evaluate their bit error rates.\",\n \"Title: Multimedia Communication Over Ofdm Mobile Wireless Networks: A Cross-Layer Diversity Approach\\nYear: 2005\\n\\nAbstract: Diversity can be used to combat multipath fading and improve the performance of mobile wireless multimedia communication systems. In this work, by considering transmission of an embedded bitstream over a slow varying Rayleigh faded environment, we develop a cross-layer diversity technique which takes advantage of both multiple description source coding and frequency diversity techniques. More specifically, assuming a frequency-selective channel, we study the packet loss behavior of an OFDM system and construct multiple independent descriptions using an FEC-based strategy. We demonstrate the superior performance of this approach using the Set Partitioning in Hierarchical Trees (SPIHT) coder.\",\n \"Title: Performance Analysis of a Pre-BLAST-DFE Technique for MISO Channels With Decentralized Receivers\\nYear: 2007\\n\\nAbstract: The performance of a pre-Bell Laboratories Layered Space-Time Architecture (BLAST)-decision feedback equalization (DFE) technique with Tomlinson-Harashima precoding and decentralized receivers, operating over multiple-input single-output (MISO) frequency-selective fading channels, is evaluated. First, we derive the probability of symbol error for Tomlinson-Harashima precoding operating over single...\",\n \"Title: An algorithm for wireless relay placement\\nYear: 2009\\n\\nAbstract: An algorithm is given for placing relays at spatial positions to improve the reliability of communicated data in a sensor network. The network consists of many power-limited sensors, a small set of relays, and a receiver. For each sensor, the receiver receives a direct signal as well as an indirect signal from one of the available relays. The relays rebroadcast the transmissions in order to achieve diversity at the receiver. Both amplify-and-forward and decode-and-forward relay networks are considered. Channels are modeled with Rayleigh fading, path loss, and additive white Gaussian noise. Performance analysis and numerical results are given.\",\n \"Title: Concatenated block codes for unequal error protection of embedded bit streams.\\nYear: 2012\\n\\nAbstract: A state-of-the-art progressive source encoder is combined with a concatenated block coding mechanism to produce a robust source transmission system for embedded bit streams. The proposed scheme efficiently trades off the available total bit budget between information bits and parity bits through efficient information block size adjustment, concatenated block coding, and random block interleavers. The objective is to create embedded codewords such that, for a particular information block, the necessary protection is obtained via multiple channel encodings, contrary to the conventional methods that use a single code rate per information block. This way, a more flexible protection scheme is obtained. The information block size and concatenated coding rates are judiciously chosen to maximize system performance, subject to a total bit budget. The set of codes is usually created by puncturing a low-rate mother code so that a single encoder-decoder pair is used. The proposed scheme is shown to effectively enlarge this code set by providing more protection levels than is possible using the code rate set directly. At the expense of complexity, average system performance is shown to be significantly better than that of several known comparison systems, particularly at higher channel bit error rates.\",\n \"Title: Asymptotic Performance Of Digital Communication Over Fading Channels\\nYear: 2007\\n\\nAbstract: This paper(1) presents a simple way to obtain the asymptotic performance of various digital communications systems operating over fading channels. The resulting expression for performance contains only the inverse average SNR raised to the system's diversity order, by averaging the conditional error probability (conditioned on the fading) with the dominant term in the fading density function. The proposed approach often renders simple closed-form asymptotic error probabilities (ASEPs), even when the corresponding closed-form actual error probabilities (ACEPs) are too difficult to find, such as those in generalized selection combining, denoted by GSC(m, L), where the strongest m branches from L (1 <= m <= L) total branches are selected and combined. Using the proposed approach, the paper derives simple closed-form ASEPs for GSC(m, L) which show its diversity order and SNR gaps among different m, over both iid and non-iid Rayleigh fading channels for both MPSK and QAM. It is found that the SNR gaps of GSC(m,L) are not a function of modulation type or orders. In addition, the paper also presents simple closed-form ASEPs for a Nakagami-m fading channel with both MPSK and QAM in conjunction with maximal ratio combining (MRC).\",\n \"Title: Optimal Allocation Of Bandwidth For Minimum Battery Consumption\\nYear: 2005\\n\\nAbstract: In general, a power amplifier utilizes battery energy more efficiently with a higher transmission power. For a given message, a given bandwidth constraint and a given performance constraint, different allocations of the bandwidth among source coding, channel coding and modulation result in different amounts of battery usage. We propose a method to optimize the bandwidth allocation and minimize the battery consumption due to transmission. Our results show that with the optimal allocation, significant reduction in battery consumption can be achieved without sacrificing the system performance.\",\n \"Title: Delay analysis of block coded transmission over the Gilbert-Elliott channel with interleaving and retransmission strategy\\nYear: 2000\\n\\nAbstract: To determine the end-to-end delay in block coded transmission over the Gilbert-Elliott (1960, 1963) channel with interleaving and a retransmission strategy, the probability distribution of the number of transmissions that a packet has to go through before it succeeds has to be found. We propose an approximate method to evaluate the distribution when the error statistics are dependent. The end-to-end delay is then examined. Our study provides a way to choose an error-control scheme (i.e., an interleaver of an appropriate size with a retransmission protocol), which meets both the delay constraint and a reliability requirement\",\n \"Title: Minimization of Expected Distortion with Layer-Selective Relaying of Two-Layer Superposition Coding.\\nYear: 2013\\n\\nAbstract: This paper considers a relay system using two-layer superposition coding to minimize the expected distortion of a Gaussian source at the destination node. For the system, we propose two types of layer- selective relaying based on the local decoding result at the relay and the decoding result at the destination node fed back to the relay. One type of the proposed scheme uses decode-and-forward (DF) in the design of the relay signals, while the other type uses both DF and amplify-and-forward (AF). For the proposed scheme, we analyze the outage probabilities and evaluate the expected distortion according to the relay location. The results reveal that the proposed scheme improves the finite SNR performance, in particular when the relay node is closer to the source node than it is to the destination node.\",\n \"Title: Video coding for a time varying tandem channel with feedback\\nYear: 2005\\n\\nAbstract: Summary form only given. A robust scheme for the efficient transmission of packet video over a tandem wireless Internet channel is extended to a time varying scenario with a feedback channel. This channel is assumed to have bit errors (due to noise and fading on the wireless portion of the channel) and packet erasures (due to congestion on the wired portion). Simulation results showed that refined estimation can dramatically improve the performance for varying channel conditions, and that combined feedback of both channel conditions and ACK/NACK information can further improve system performance compared with the feedback of just one type of information.\",\n \"Title: A Markov Model for Block Errors on Fading Channels\\nYear: 1996\\n\\nAbstract: — In this paper, we investigate the behavior of block errors which arise in data transmission on fading channels. Our approach is more detailed than previous studies, in that it takes into account the specific coding/modulation scheme and it tracks the fading process symbol by symbol. It is shown that a Markov approximation for the block error process (possibly degenerating into an iid process for sufficiently fast fading) is a very good model for a broad range of parameters. Also, it is observed that the relationship between the marginal error rate and the transition probability is largely insensitive to pa ram- eters such as block length, degree of forward error correction and modulation format, and only depends on an appropriately normalized version of the Doppler frequency. This observation leads to a unified approach for the channel modeling which simplifies the performance analysis of upper-layer protocols.\",\n \"Title: Cross-layer distributed joint power control and scheduling for delay-constrained applications over CDMA-based wireless ad-hoc networks\\nYear: 2010\\n\\nAbstract: In this paper, we propose a cross-layer distributed power control and scheduling protocol for delay-constrained applications over mobile CDMA-based ad hoc wireless networks. Herein, we propose a novel scheme where power control is employed to combat delay occurring on multi-hop wireless ad hoc networks via cross-layer information exchange. Based on that, a distributed power control and scheduling protocol is proposed to control the incurred delay as well as the multiple access interference (MAI). Unlike other previous work on power control and scheduling, we also investigate the impact of Doppler spread upon the system performance, and provide a robust system which employs a combination of power control, and coding/interleaving to combat the effects of Doppler spread by exploiting the time diversity when the Doppler spread gets large. Hence, our proposed approach can function appropriately over a wide range of channel conditions.\",\n \"Title: Weight distribution of a class of binary block codes formed from RCPC codes.\\nYear: 2005\\n\\nAbstract: In this paper, we study the weight enumerator and the numerical performance of a class of binary linear block codes formed from a family of rate-compatible punctured convolutional (RCPC) codes. Also, we present useful numerical results for a well-known family of RCPC codes.\",\n \"Title: A First-Order Markov Model For Correlated Nakagami-M Fading Channels\\nYear: 2002\\n\\nAbstract: In this paper, we propose a first-order Markov model for generalized Nakagami-m flat fading channels. Using a moment generating function (MGF) approach, we derive the parameters of the proposed model for any value of the fading severity index m greater than or equal to 0.5. The proposed model is a generalized version of the one proposed earlier by Zorzi et al for flat Rayleigh fading channels. For m = 1, we show that our generalized model gives the same parameter values obtained using Zorzi's approach. Our generalized model thus encompasses Zorzi's model as a special case. We illustrate the usefulness of our proposed Markov model by applying it to the analysis of the throughput and energy efficiency performance of a link layer (LL) protocol with backoff on wireless fading links with different values of the m-parameter (= 0.5,1,4).\",\n \"Title: Performance Analysis Of N-Channel Symmetric Fec-Based Multiple Description Coding For Ofdm Networks\\nYear: 2011\\n\\nAbstract: Recently, multiple description source coding has emerged as an attractive framework for robust multimedia transmission over packet erasure channels. In this paper, we mathematically analyze the performance of n-channel symmetric FEC-based multiple description coding for a progressive mode of transmission over orthogonal frequency division multiplexing (OFDM) networks in a frequency-selective slowly-varying Rayleigh faded environment. We derive the expressions for the bounds of the throughput and distortion performance of the system in an explicit closed form, whereas the exact performance is given by an expression in the form of a single integration. Based on this analysis, the performance of the system can be numerically evaluated. Our results show that at high SNR, the multiple description encoder does not need to fine-tune the optimization parameters of the system due to the correlated nature of the subcarriers. It is also shown that, despite the bursty nature of the errors in a slow fading environment, FEC-based multiple description coding without temporal coding provides a greater advantage for smaller description sizes.\",\n \"Title: Performance Analysis of Optimum and Suboptimum Selection Diversity Schemes on Rayleigh Fading Channels With Imperfect Channel Estimates\\nYear: 2007\\n\\nAbstract: In this paper, we present a comparative analysis on the effects of channel estimation errors on the performance of optimum and suboptimum selection diversity (SD) receivers on Rayleigh-fading channels. By modeling the estimation errors as independent complex Gaussian random variables, we derive simple closed-form expressions for the average probability of error for both optimum and suboptimum SD s...\",\n \"Title: Superposition MIMO Coding for the Broadcast of Layered Sources.\\nYear: 2011\\n\\nAbstract: We propose superposition multiple-input multiple-output (MIMO) coding for the transmission of unequally important sources in a point-to-multipoint system. First, a tradeoff between Alamouti code and spatial multiplexing (V-BLAST) is analyzed in terms of the average bit error rate (BER), where the maximum data rates of both MIMO schemes are set to be equal. The results show that for a given target ...\",\n \"Title: Optimal Sensing Disruption for a Cognitive Radio Adversary\\nYear: 2010\\n\\nAbstract: Spectrum sensing vulnerabilities in cognitive radio (CR) networks are being actively investigated, where most research focuses on mechanisms that deal with possible attacks without examining optimal sensing disruption strategies. This paper addresses the optimal design and analysis of a power-limited intelligent adversary to a CR network. The adversary targets unused bands and puts energy into them so that the number of unused bands appears reduced to secondary users. This is called sensing disruption. The optimal disruption strategy is obtained by maximizing the average number of false detections under the adversary's power constraint. It is shown that, for a CR network where energy detection is utilized by secondary users, the optimal sensing disruption strategy for noise spoofing for a CR adversary is equal-power partial-band spoofing. Numerical results and analyses of the optimal sensing disruption are provided.\",\n \"Title: Performance Of Space-Time Spreading With Correlated Fading And Channel Estimation\\nYear: 2002\\n\\nAbstract: Space-time block codes (STBC) have been proposed as a less complex alternative to space-time trellis codes for achieving transmit diversity. Application of such STBCs to code division multiple access (CDMA) systems is called space-time spreading (STS). STS schemes have been considered under the assumption of independent transmit fades and ideal channel state information (CSI). However, the performance of these schemes deteriorates when the above assumptions are relaxed in a realistic system. We study here analytic-ally the performance degradation due to both the fade correlation and the channel estimation errors.\",\n \"Title: Statistical modeling of W-CDMA signals for use over frequency-selective multipath channels\\nYear: 2004\\n\\nAbstract: This letter presents a mathematical model for the statistics of wideband code-division multiple-access signals which experience multipath fading. The statistics are obtained from numerically generated signals, and are then modeled with an offset noncentral chi distribution with three degrees of freedom. The mathematical model is tested against the numerically generated data by the use of a chi-squ...\",\n \"Title: Guest editorial: wireless video transmission\\nYear: 2010\\n\\nAbstract: The 20 papers in this special issue on wireless video transmissions are divided into four categories: wireless video streaming, optimization and scheduling; wireless video broadcast/multicast; retransmission techniques; and video quality assessment.\",\n \"Title: Special issue on evolving from 3G deployment to 4G definition.\\nYear: 2002\\n\\nAbstract: The deployment of 3G mobile systems is now getting underway, with roll-out plans being affected by a number of mutually reinforcing factors. These factors include policies affecting the business case for operators who need to erate return on their investment in infrastructure within a reasonable time span, and the general economic situation impacting the propensity of operators to take such infrastructure investment risks coupled with the propensity of end to pay for new and improved services. This is all taking place in an environment where expectations have, for many years, followed the technology curve of rapidly improving performance and capability at steadily declining cost.\",\n \"Title: Chernoff-Type Bounds for the Gaussian Error Function.\\nYear: 2011\\n\\nAbstract: We study single-term exponential-type bounds (also known as Chernoff-type bounds) on the Gaussian error function. This type of bound is analytically the simplest such that the performance metrics in most fading channel models can be expressed in a concise closed form. We derive the conditions for a general single-term exponential function to be an upper or lower bound on the Gaussian error functio...\",\n \"Title: Optimized Unequal Error Protection Using Multiplexed Hierarchical Modulation\\nYear: 2012\\n\\nAbstract: With progressive image or scalable video encoders, as more bits are received, the source can be reconstructed with progressively better quality. These progressive codes have gradual differences of importance in their bitstreams, which necessitates multiple levels of unequal error protection (UEP). One practical method of achieving UEP is based on a constellation of nonuniformly spaced signal points, or hierarchical constellations. However, hierarchical modulation can achieve only a limited number of UEP levels for a given constellation size. Though hierarchical modulation has been intensively studied for digital broadcasting or multimedia transmission, most work has considered only two layered source coding, and methods of achieving a large number of UEP levels for progressive transmission have rarely been studied. In this paper, we propose a multilevel UEP system using multiplexed hierarchical quadrature amplitude modulation (QAM). We show that multiple levels of UEP are achieved by the proposed multiplexing method. When the BER is dominated by the minimum Euclidian distance, we derive an optimal multiplexing approach which minimizes both the average and peak powers. We next propose an asymmetric hierarchical QAM which reduces the peak-to-average power ratio (PAPR) of the proposed UEP system without any performance loss. Numerical results show that the performance of progressive transmission over Rayleigh fading channels is significantly enhanced by the proposed methods.\",\n \"Title: Channel coding for progressive images in a 2-D time-frequency OFDM block with channel estimation errors.\\nYear: 2009\\n\\nAbstract: Coding and diversity are very effective techniques for improving transmission reliability in a mobile wireless environment. The use of diversity is particularly important for multimedia communications over fading channels. In this work, we study the transmission of progressive image bitstreams using channel coding in a 2-D time-frequency resource block in an OFDM network, employing time and frequency diversities simultaneously. In particular, in the frequency domain, based on the order of diversity and the correlation of individual subcarriers, we construct symmetric n -channel FEC-based multiple descriptions using channel erasure codes combined with embedded image coding. In the time domain, a concatenation of RCPC codes and CRC codes is employed to protect individual descriptions. We consider the physical channel conditions arising from various coherence bandwidths and coherence times, leading to a range of orders of diversities available in the time and frequency domains. We investigate the effects of different error patterns on the delivered image quality due to various fade rates. We also study the tradeoffs and compare the relative effectiveness associated with the use of erasure codes in the frequency domain and convolutional codes in the time domain under different physical environments. Both the effects of intercarrier interference and channel estimation errors are included in our study. Specifically, the effects of channel estimation errors, frequency selectivity and the rate of the channel variations are taken into consideration for the construction of the 2-D time-frequency block. We provide results showing the gain that the proposed model achieves compared to a system without temporal coding. In one example, for a system experiencing flat fading, low Doppler, and imperfect CSI, we find that the increase in PSNR compared to a system without time diversity is as much as 9.4 dB.\",\n \"Title: Optimal Transmission of Progressive Sources Based on the Error Probability Analysis of SM and OSTBC\\nYear: 2014\\n\\nAbstract: This paper studies the optimal design of multimedia progressive communication systems that are combined with low-complex open-loop multiple-input multiple-output techniques. First, we analyze the behavior of the crossover point of the error probability curves for orthogonal space-time block codes (OSTBC) and spatial multiplexing (SM) with a zero-forcing linear receiver. We mathematically prove that, in the high signal-to-noise ratio (SNR) regime, for both the information outage probability and the uncoded bit error rate, as data rate increases, the crossover point for the error probability monotonically decreases, and the crossover point for the SNR monotonically increases. We prove that this holds, regardless of the numbers of transmit and receive antennas and the spatial multiplexing rate of OSTBC. We next show how those results can be exploited for the optimal transmission of progressive sources, such as embedded image, which require unequal target error rates in their bitstream. That is, the computational complexity involved with the optimal space-time coding of progressive bitstream can be decreased.\",\n \"Title: Spectrum Broadening Due to Phase Noise Interaction in Cognitive Radio Systems\\nYear: 2010\\n\\nAbstract: Spectrum broadening due to the interaction of local oscillator (LO) phase noise with an adjacent channel signal is analyzed, and applied to the situation where a cognitive radio (CR) detector experiences in-band interference from a strong adjacent channel signal. Expressions for the resulting in-band interference and modified detection performance are presented.\",\n \"Title: Enhanced Selection Combining by Choosing Independently the Strongest Real Component and the Strongest Imaginary Component of all Channels\\nYear: 2014\\n\\nAbstract: Conventional selection combining (SC) selects the antenna with the largest channel envelope. In this paper, we propose to select the largest real part and largest imaginary part of the channel individually from all antennas for 2 dimensional (2-D) signals such as MPSK or MQAM. We derive the asymptotic symbol error rate (ASER) expression for this system and it is found that it has the same diversity order (DO) as does conventional SC, but has an SNR gain over conventional SC. The paper presents a closed-form expression for this gain, which monotonically increases with the DO, and is independent of the constellation size for a given modulation format. Simulation results are shown to match the theoretical analysis.\",\n \"Title: Cooperative Relaying of Superposition Coding with Simple Feedback for Layered Source Transmission.\\nYear: 2013\\n\\nAbstract: We consider a relay network that delivers a Gaussian source by employing successive refinement source coding and superposition coding of layers at the source node and successive decoding at the relay and destination nodes. For the network, making use of the decoding results at the relay and destination nodes of the first transmission, an efficient relaying strategy of layers is proposed to minimize the expected distortion (ED) when only the average channel state information is available at the source node. Three types of the proposed scheme, defined as Prop-DF, using decode-and-forward signals, Prop-AF, using amplify-and-forward signals, and Prop-MF, using mixed-forward signals, are addressed and analyzed in terms of the outage probability and distortion exponent. Unlike other studies, we have also taken the relay location into account in deriving the distortion exponent showing the high SNR behavior of the ED. The results show that the proposed scheme increases the distortion exponent up to twice that of the conventional relaying schemes when the relay is close to the source node, and that Prop-MF provides the best performance for most relay locations.\",\n \"Title: Multi-User Resource Allocation for Downlink Multi-Cluster Multicarrier DS CDMA System.\\nYear: 2011\\n\\nAbstract: In this paper, we consider an adaptive multi-user resource allocation for the downlink transmission of a multi-cluster tactical multicarrier DS CDMA network. The goal is to maximize the sum packet throughput, subject to transmit power constraints. Since the objective function turns out to be noncovex and nondifferentiable, we propose a simple iterative bisection algorithm. At each iteration, a clo...\",\n \"Title: The effects of channel estimation errors on a nonlinear precoder for multiple antenna downlink channels\\nYear: 2009\\n\\nAbstract: The effects of channel estimation errors on the performance of a system employing Tomlinson-Harashima precoding and the QR decomposition, operating over multiple antenna frequency-flat fading channels with decentralized receivers, is evaluated. The QR decomposition of the channel matrix is employed to arrive at an equivalent channel where successive interference cancellation at the transmitter can be used to remove the effect of the multiuser interference. However, in the case of imperfect channel estimation, it is not possible to remove the effect of the multiuser interference due to a mismatch between the precoder and the channel. Consequently, it is necessary to include the estimation error in deriving the probability of symbol error. We also provide simulations to corroborate the analytical results.\",\n \"Title: Error-resilient video communications over CDMA networks with a bandwidth constraint.\\nYear: 2006\\n\\nAbstract: We present an adaptive video transmission scheme for use in a code-division multiple-access network, which incorporates efficient bandwidth allocation among source coding, channel coding, and spreading under a fixed total bandwidth constraint. We derive the statistics of the received signal, as well as a theoretical bound on the packet drop rate at the receiver. Based on these results, a bandwidth allocation algorithm is proposed at the packet level, which incorporates the effects of both the changing channel conditions and the dynamics of the source content. Detailed simulations are done to evaluate the performance of the system, and the sensitivity of the system to estimation error is presented.\",\n \"Title: Source-channel rate optimization for progressive image transmission over block fading relay channels [Transactions Papers]\\nYear: 2010\\n\\nAbstract: In this paper, we are concerned with the design and analysis of joint source-channel coding schemes for block fading channels with relay-assisted distributed spatial diversity. Assuming a progressive image coder with a constraint on the transmission bandwidth, we formulate a joint source-channel rate allocation scheme that maximizes the expected source throughput. Specifically, using Gaussian as well as BPSK inputs on flat Rayleigh fading channels, we lower bound the average packet error rate by the corresponding mutual information outage probability, and derive the average throughput expression as a function of channel code rates as well as channel SNR for both a frequency-division multiplexing-based baseline system without relaying, and a half-duplex relay system with a decode-and- forward protocol. At high signal-to-noise ratio (SNR), for the systems considered in this paper, we show that our rate optimization problem is a convex function of the channel code rates, and we show that a known recursive algorithm can be used to predict the performance of both systems.\",\n \"Title: Asymptotic Symbol Error Rate for Selection Combining on Nakagami-m Fading Channels\\nYear: 2008\\n\\nAbstract: This paper derives closed-form asymptotic symbol error rates (ASERs) for MPSK and MQAM signals with selection combining (SC) over Nakagami-m fading channels. It also presents a closed-form expression for the power loss of SC compared to maximal ratio combining (MRC) over a Nakagami-m fading channel. It is found that this power gap is a function of only the number (L) of independent Nakagami-m channels and the fading parameter m. For a fixed m, the gap monotonically increases with L. For a fixed L, the gap monotonically increases with m and approaches 10log(10) L dB (the asymptotic gap between MRC and SC in an AWGN channel) as m -> infinity. In addition, numerical results show the accuracy of the ASERs obtained from closed-form expressions for both MRC and SC with MPSK and MQAM signals for large SNRs. They also show that the SNR gap is identical to that predicted by the analysis for arbitrary L and m.\",\n \"Title: Cross Layer Resource Allocation Design for Uplink Video OFDMA Wireless Systems\\nYear: 2011\\n\\nAbstract: We study an uplink video communication system with multiple users in a centralized wireless cell. The multiple access scheme is Orthogonal Frequency Division Multiple Access (OFDMA). Both physical layer channel state information (CSI) and application layer rate distortion (RD) information of video streams are collected by the base station. With the goal of minimizing the average video distortion across all the users in the system, we design an iterative resource allocation algorithm for subcarrier assignment and power allocation. Based on the physical layer resource allocation decision, the user will adapt the application layer video source coding rate. To show the advantage of this cross layer algorithm, numerical results are compared with two baseline resource allocation algorithms using only physical layer information or only application layer information. Bit-level simulation results are presented which take into account the imperfection of the video coding rate control, as well as channel errors.\",\n \"Title: Parallel acquisition of spread-spectrum signals with antenna diversity\\nYear: 1997\\n\\nAbstract: The use of antenna diversity is investigated for improving the parallel acquisition performance of a direct-sequence spread-spectrum signal in both flat and frequency-selective fading channels. Noncoherent combining techniques are analyzed because coherent diversity techniques, such as maximal ratio combining, cannot be employed prior to initial acquisition. A major application of this work is to cellular communications\",\n \"Title: Performance Degradation Due to MAI in OFDMA-Based Cognitive Radio\\nYear: 2010\\n\\nAbstract: We consider a convolutionally coded orthogonal frequency-division multiple access (OFDMA) based cognitive radio system where each user achieves perfect synchronization for its own signal, while different users are asynchronized due to random timing offsets. The presence of asynchronous secondary users introduces potential multiple access interference (MAI) to each primary user's receiver. The strength of the MAI is determined by the secondary users' transmission powers, and their distances and frequency separations to the primary user. Expressions for the primary user's pairwise error probability and average probability of error are derived, and an error floor prediction method is presented. Finally, the trade-off between the MAI to the primary user and the secondary users' performances are investigated through numerical examples and simulations.\",\n \"Title: Multicarrier CDMA overlay for ultra-wideband communications\\nYear: 2004\\n\\nAbstract: In this letter, the performance of multicarrier code-division multiple-access (CDMA) systems is studied in the presence of narrowband interference for future ultra-wideband (UWB) communications. A Nakagami fading channel is assumed, and notch filters along with diversity techniques are used in the multicarrier CDMA receiver. A complete performance analysis of error probability is given. It is shown that when the number of subcarriers jammed by narrowband interference is small, the multicarrier receiver without notch filters can work well, due to the gain of frequency diversity from nonjammed subcarriers. On the other hand, when the number of subcarriers jammed by the narrowband interference is large, using notch filters can improve the multicarrier system performance significantly.\",\n \"Title: Uplink Resource Management for Multiuser OFDM Video Transmission Systems: Analysis and Algorithm Design\\nYear: 2013\\n\\nAbstract: We consider a multiuser OFDM system in which users want to transmit videos via a base station. The base station knows the channel state information (CSI) as well as the rate distortion (RD) information of the video streams and tries to allocate power and spectrum resources to the users according to both physical layer CSI and application layer RD information. We derive and analyze a condition for the optimal resource allocation solution in a continuous frequency response setting. The optimality condition for this cross layer optimization scenario is similar to the equal slope condition for conventional video multiplexing resource allocation. Based on our analysis, we design an iterative subcarrier assignment and power allocation algorithm for an uplink system, and provide numerical performance analysis with different numbers of users. Comparing to systems with either only physical layer or only application layer information available at the base station, our results show that the user capacity and the video PSNR performance can be increased significantly by using cross layer design. Bit-level simulations which take into account the imperfection of the video coding rate control, the variation of RD curve fitting, as well as channel errors, are presented.\",\n \"Title: Design of multi-input multi-output systems based on low-density Parity-check codes\\nYear: 2005\\n\\nAbstract: We design serial concatenated multi-input multi-output systems based on low-density parity-check (LDPC) codes. We employ a receiver structure combining the demapper/detector and the decoder in an iterative fashion. We consider the a posteriori probability (APP) demapper, as well as a suboptimal demapper incorporating interference cancellation with linear filtering. Extrinsic information transfer (...\",\n \"Title: A Multiple Description Coding and Delivery Scheme for Motion-Compensated Fine Granularity Scalable Video\\nYear: 2008\\n\\nAbstract: Motion-compensated fine-granularity scalability (MC-FGS) with leaky prediction has been shown to provide an efficient tradeoff between compression gain and error resilience, facilitating the transmission of video over dynamic channel conditions. In this paper, we propose an n-channel symmetric motion-compensated multiple description (MD) coding and transmission scheme for the delivery of scalable video over orthogonal frequency division multiplexed systems, utilizing the concepts of partial and leaky predictions. We investigate the proposed MD coding and transmission scheme using a cross-layer design perspective. In particular, we construct the symmetric motion-compensated MD codes based on the diversity order of the channel, defined as the ratio of the overall bandwidth of the system to the coherence bandwidth of the channel. We show that knowing the diversity order of a physical channel can assist an MC-FGS video coder in selecting the motion-compensation prediction point, as well as on the use of leaky prediction. More importantly, we illustrate how the side information can reduce the drift management problem associated with the construction of symmetric motion-compensated MD codes. We provide results based on both an information-theoretic approach and simulations.\",\n \"Title: A resource allocation algorithm for real-time streaming in cognitive networks\\nYear: 2009\\n\\nAbstract: Cognitive radios have been proposed as a means to implement efficient reuse of the licensed spectrum. Commonly, wireless networks are characterized by a fixed spectrum assignment policy. The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. We consider a simple single-cell scenario with two data up-links, one licensed to use the spectral resource (primary) and the other unlicensed (secondary or cognitive). It is assumed that the cognitive user accesses the channel only when the channel is sensed idle. An ON-OFF channel model is used for the primary link, where traffic statistical characteristics are taken into account. We study a practical resource allocation algorithm that assigns the uplink to the secondary users according to a channel-and-queues aware scheduler when primary link OFF periods are sensed. We fit the resource allocation algorithm to the widely investigated orthogonal frequency division multiple access (OFDMA) scheme and we exploit multiuser diversity by applying a smart power allocation within independent OFDMA subchannels. A video encoder rate control is introduced in order to limit the video frame loss due to overflow that trades the video frame loss probability with the overall encoding quality. Lastly, the performance of the cognitive network model is investigated under the proposed resource allocation algorithm.\",\n \"Title: Cooperative and Constrained MIMO Communications in Wireless Ad Hoc/Sensor Networks\\nYear: 2010\\n\\nAbstract: In this paper, we investigate the issue of cooperative node selection in MIMO communications for wireless ad hoc/sensor networks, where a source node is surrounded by multiple neighbors and all of them are equipped with a single antenna. Given energy, delay and data rate constraints, a source node dynamically chooses its cooperating nodes from its neighbors to form a virtual MIMO system with the destination node (which is assumed to have multiple antennas), as well as adaptively allocates the power level and adjusts the constellation size for each of the selected cooperative nodes. In order to optimize system performance, we jointly consider the optimization of all these parameters, given the aforementioned system constraints. We assume that the source node either has CSI, or has no CSI. Heuristic algorithms, such as maximal channel gain (MCG) and least channel correlation (LCC) algorithms are proposed in order to exploit available system information and to solve the constrained optimization problem.\",\n \"Title: Tradeoff between diversity gain and interference suppression in a MIMO MC-CDMA system\\nYear: 2005\\n\\nAbstract: In this paper, the uplink of an asynchronous multi-carrier direct-sequence code-division multiple-access (MC-DS-CDMA) system with multiple antennas at both the transmitter and the receiver is considered. We analyze the system performance over a spatially correlated Rayleigh fading channel with multiple-access interference (MAI), and evaluate the antenna array performance with joint fading reductio...\",\n \"Title: MMSE interference suppression for coded multicarrier DS-CDMA in the presence of intermodulation\\nYear: 1999\\n\\nAbstract: This paper presents a coded multicarrier (MC) DS-CDMA system which, by the use of a linear convolutional code (CC) and minimum mean-squared error (MMSE) receiver, achieves frequency diversity instead of path diversity as in a conventional single carrier RAKE DS-CDMA, and has the ability to partially compensate for the distortion introduced by a nonlinear amplifier at the transmitter. A frequency selective Rayleigh fading channel is decomposed into M frequency non-selective channels, based on the channel coherence bandwidth. A rate 1/M convolutional code, after being interleaved, is used to modulate M different DS-CDMA waveforms. The new system is shown to effectively suppress multiple access interference in the presence of intermodulation distortion\",\n \"Title: The effects of spatial diversity and imperfect channel estimation on wideband MC-DS-CDMA and MC-CDMA\\nYear: 2009\\n\\nAbstract: In our previous work, we compared the theoretical bit error rates of multi-carrier direct sequence code division multiple access (MC-DS-CDMA) and multi-carrier code division multiple access (MC-CDMA). To ensure a fair comparison, we constrained both schemes to the same bandwidth, information rate, and energy-per-bit, and these constraints resulted in a possible trade-off between diversity gain and channel estimation errors between the two schemes. While only a single-input single-output (SISO) system was considered in our previous work, in this paper, we extend the comparison to a multiple-input multiple-output (MIMO) system which employs Alamouti space-time block coding at each sub-carrier frequency to achieve spatial diversity. We consider only those cases where MC-CDMA has higher frequency diversity than MC-DS-CDMA. Since increases in diversity yield diminishing gains, we conclude that the addition of spatial diversity to this multi-carrier comparison benefits MCDS-CDMA more than MC-CDMA. To determine whether these gains for MC-DS-CDMA are enough to offset the difference in frequency diversity between the two schemes, we derive closed-form expressions for the bit error probabilities of both schemes, and we compare the MIMO results against those of the SISO system for different information rates, number of users, and number of pilot symbols per channel estimate.\",\n \"Title: Optimal Linear-Combining Receiver For Decode-And-Forward Relays Using Superposition Coding\\nYear: 2013\\n\\nAbstract: We consider a relay network with a single source, a single destination, and multiple relays. The relays are half-duplex and use the decode-and-forward protocol. A layered Gaussian source partitioned into two layers is transmitted. The source broadcasts a message consisting of two layers to all the relays using superposition coding. Each relay re-encodes and forwards all its successfully decoded layers to the destination using an orthogonal channel. Superposition coding is used only if both layers are forwarded. We propose a novel approach to derive the optimal linear-combining receiver at the destination. Numerical results show that the two-layer scheme using superposition coding outperforms a conventional one-layer scheme in terms of average throughput and expected distortion.\",\n \"Title: Trade-Off Between Diversity and Channel Estimation Errors in Asynchronous MC-DS-CDMA and MC-CDMA\\nYear: 2008\\n\\nAbstract: This paper investigates the trade-off between diversity and channel estimation errors for asynchronous multi-carrier CDMA (MC-CDMA) and multicarrier direct-sequence CDMA (MC-DS-CDMA). We construct a side-by-side comparison between the two systems by assuming equal operating and channel conditions. Both systems perform pilot-symbol- aided channel estimation and maximal ratio combining at the receiv...\",\n \"Title: Motion-Compensated Scalable Video Transmission Over MIMO Wireless Channels\\nYear: 2013\\n\\nAbstract: We study motion compensated fine granular scalable (MC-FGS) video transmission over multiinput multioutput (MIMO) wireless channels applicable to video streaming, where leaky and partial prediction schemes are applied in the enhancement layer of MC-FGS to exploit the tradeoff between error propagation and coding efficiency. For reliable transmission, we propose unequal error protection (UEP) by considering a tradeoff between reliability and data rates, which are controlled by forward error correction and MIMO mode selection to minimize the average distortion. In a high Doppler environment, where it is hard to get an accurate channel estimate, we investigate the performance of the proposed MC-FGS video transmission scheme with joint control of both the leaky and partial prediction parameters, and the UEP. In a slow fading channel, where the channel throughput can be estimated at the transmitter, adaptive control of prediction parameters is considered.\",\n \"Title: Coarse Acquisition Performance of Spectral-Encoded UWB Communication Systems in the Presence of Narrow-Band Interference.\\nYear: 2007\\n\\nAbstract: It is known that a major practical implementation challenge of ultra-wideband (UWB) receivers is the design of the coarse acquisition stage. Due to the fine time resolution of UWB signals, the acquisition stage has to acquire a large number of low-energy multipath components, with no or little knowledge of the state of the channel. In addition, the complexity further increases with the presence of...\",\n \"Title: Tradeoffs of Source Coding, Channel Coding and Spreading in Frequency Selective Rayleigh Fading Channels\\nYear: 2002\\n\\nAbstract: This paper investigates the tradeoffs of source coding, channel coding and spreading in CDMA systems. We consider a system consisting of an image source coder, a convolutional channel coder, an interleaver, and a direct sequence spreading module. With different allocations of bandwidth to source coding, channel coding and spreading, the system is analyzed over a frequency selective Rayleigh fading channel. The performance of the system is evaluated using the cumulative distribution function of peak signal-to-noise ratio. Tradeoffs of different components of the system are determined through simulations. We show that, for a given bandwidth, an optimal allocation of that bandwidth can be found. Tradeoffs among the parameters allow us to tune the system performance to specific requirements.\",\n \"Title: Higher Order Constellation with Simplified Minimum Mean Square Error (MMSE) Receiver in CDMA Channel with Tone Interference\\nYear: 2000\\n\\nAbstract: It has previously been shown that employing a higher order constellation in conjunction with CDMA can improve the performance of the multiuser system in the presence of severe ISI and narrowband Gaussian interference. We study a similar scenario here, except that the narrowband Gaussian interferer is replaced with a tone interferer. It is shown that the use of the higher order alphabet size is also useful in the tone interference case. Also, we derive lower and upper bounds on the performance of an MMSE receiver in a multiuser, flat fading scenario. Later we apply the same technique to a multiuser, frequency selective fading scenario with negligible or mild ISI.\",\n \"Title: Adaptive Modulation for OFDM-Based Multiple Description Progressive Image Transmission\\nYear: 2008\\n\\nAbstract: This paper addresses the use of adaptive modulation in progressive image transmission with multiple description coding in conjunction with an Orthogonal Frequency Division Multiplexing (OFDM) system. Specifically, two adaptive systems are considered: variable rate with fixed power, and variable rate with variable power. An algorithm is proposed to allocate power and constellation size at each subchannel by maximizing the throughput. Simulation results confirm that cross-layer optimization with adaptive modulation enhances system performance.\",\n \"Title: Simple closed-form asymptotic symbol error rate of selection combining and its power loss compared to the maximal ratio combining over Nakagami m fading channels\\nYear: 2010\\n\\nAbstract: This paper derives closed-form asymptotic symbol error rates (ASERs) for MPSK and MQAM signals with selection combining (SC) over Nakagami-m fading channels. It also presents a closed-form expression for the power loss of SC compared to maximal ratio combining (MRC) over a Nakagami- m fading channel. It is found that this power gap is a function of only the number (L) of independent Nakagami-m channels and the fading parameter m. For a fixed m, the gap monotonically increases with L. For a fixed L, the gap monotonically increases with m and approaches 10 log10 L dB (the asymptotic gap between MRC and SC in an AWGN channel) as m ¿ ¿. In addition, numerical results show the accuracy of the ASERs obtained from closed-form expressions for both MRC and SC with MPSK and MQAM signals for large SNRs. They also show that the SNR gap is identical to that predicted by the analysis for arbitrary L and m.\",\n \"Title: Channel Coding Optimization Based on Slice Visibility for Transmission of Compressed Video over OFDM Channels.\\nYear: 2012\\n\\nAbstract: Optimization of multimedia transmissions over wireless channels should be aimed at maximizing the video quality perceived by the final user. For transmission of video sequences over an orthogonal frequency division multiplexing (OFDM) system in a slowly varying Rayleigh faded environment, we develop a cross-layer technique, based on a slice loss visibility (SLV) model used to evaluate the visual importance of each slice. In particular, taking into account the visibility scores available from the bitstream, depending on the scenario, we optimize the mapping of video slices within a 2-D time-frequency resource block and/or the channel code rates, in order to better protect more visually important slices. The proposed algorithm is investigated for several scenarios, with different levels of information about the channel available in the optimization process. Results demonstrate that, for different physical environments and different video sequences, the proposed algorithm outperforms baseline ones which do not take into account either the SLV or the CSI in the video transmission.\",\n \"Title: On Uplink Channel Estimation in WiMAX Systems\\nYear: 2010\\n\\nAbstract: In this paper, channel estimation algorithms are proposed and compared for uplink WiMAX systems, which are OFDMA based. These algorithms are investigated based on a dynamic resource allocation scheme, and it is shown that each of them is suitable to specific system scenarios. For example, for a system with a bandwidth of 10MHz operating in the low frequency region 2-11GHz, a two-dimensional averaging algorithm outperforms other algorithms, such as a bilinear interpolation algorithm, because the correlations between the pilots and signals are sufficiently high in both the frequency and the time dimensions.\",\n \"Title: Multi-User Resource Allocation for a Distributed Multi-Carrier DS-CDMA Network.\\nYear: 2012\\n\\nAbstract: This paper addresses an adaptive multi-user resource allocation for a distributed multi-carrier direct sequence-code division multiple access (MC DS-CDMA) network. The packet throughput, which turns out to be nonconvex and nondifferentiable, is considered to measure the system performance. A sub-optimal non-cooperative power control game is proposed to adaptively allocate the transmit power, available subchannels and alphabet size by minimizing the transmit power with a transmit power constraint and a packet throughput requirement. Also, the paper investigates the effect of channel estimation error on the adaptive resource allocation in a distributed MC DS-CDMA network, and shows that using the Gaussian approximation for the signal-dependent noise can lead to a nontrivial discrepancy in system performance.\",\n \"Title: Joint Source-Channel Coding and Unequal Error Protection for Video Plus Depth\\nYear: 2015\\n\\nAbstract: We consider the joint source-channel coding (JSCC) problem of 3-D stereo video transmission in video plus depth format over noisy channels. Full resolution and downsampled depth maps are considered. The proposed JSCC scheme yields the optimum color and depth quantization parameters as well as the optimum forward error correction code rates used for unequal error protection (UEP) at the packet level. Different coding scenarios are compared and the UEP gain over equal error protection is quantified for flat Rayleigh fading channels.\",\n \"Title: Resource Allocation and Performance Analysis for Multiuser Video Transmission Over Doubly Selective Channels\\nYear: 2015\\n\\nAbstract: We consider an uplink multicarrier system with multiple video users who want to send compressed video data to the base station. In the time domain, we model the time-varying channel using Jakes' model, and in the frequency domain, each subcarrier is assumed to be independently fading. The video is scalably coded in units of a group of pictures (GOP), and users have different video rate distortion (RD) functions. At the beginning of the GOP, the base station collects both the RD information and the instantaneous channel state information (CSI) for subcarrier allocation purposes. We design a cross-layer resource allocation algorithm to assign subcarriers to users based on both the demand of the video and the quality of the channel. Once the resource allocation decision is made, the users then periodically adapt the modulation format of the subcarriers allocated according to the evolution of the CSI for the duration of the GOP. We show that our cross-layer resource allocation robustly outperforms two baseline algorithms, each of which uses only one layer of information for resource allocation.\",\n \"Title: Multiview coding and error correction coding for 3D video over noisy channels.\\nYear: 2015\\n\\nAbstract: We consider the joint source–channel coding problem of stereo video transmitted over AWGN and flat Rayleigh fading channels. Multiview coding (MVC) is used to encode the source, as well as a type of spatial scalable MVC. Our goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under the constraints that the quality of the left and right views must each be greater than predetermined PSNR thresholds at the receiver. We first consider symmetric coding, for which the quality thresholds are equal. Following binocular suppression theory, we also consider asymmetric coding, for which the quality thresholds are unequal. The optimization problem is solved using both equal error protection (EEP) and a proposed unequal error protection (UEP) scheme. An estimate of the expected end-to-end distortion of the two views is formulated for a packetized MVC bitstream over a noisy channel. The UEP algorithm uses these estimates for packet rate allocation. Results for various scenarios, including non-scalable/scalable MVC, symmetric/asymmetric coding, and UEP/EEP, are provided for both AWGN and flat Rayleigh fading channels. The UEP bit savings compared to EEP are given, and the performances of different scenarios are compared for a set of stereo video sequences.\",\n \"Title: Bounding The Performance Of The Lms Estimator For Cases Where Performance Exceeds That Of The Finite Wiener Filter\\nYear: 1998\\n\\nAbstract: The least-mean-square (LMS) estimator is a nonlinear estimator with information dependencies spanning the entire set of data fed into it. The traditional analysis techniques which are used to model this estimator obscure this, restricting the estimator to the finite set of data sufficient to span the length of its filter. The finite Wiener filter is thus often considered a bound on the performance of the LMS estimator. Several papers have reported the performance of the LMS filter exceeding that of the finite Wiener filter. In this paper, we will demonstrate a bound on the LMS estimator, which does not exclude the contributions from data outside its filter length, and which demonstrates the ability of the LMS estimator to outperform the finite Wiener filter in certain cases.\",\n \"Title: Spoofing optimization over Nakagami-m fading channels of a cognitive radio adversary.\\nYear: 2013\\n\\nAbstract: We examine the performance of a cognitive radio system in a hostile environment where an intelligent adversary tries to disrupt communications by spoofing. We analyze a cluster-based network of secondary users (SUs), where sensing is performed by the cluster head. The adversary may attack during the sensing interval to limit access for SUs by transmitting a Gaussian noise spoofing signal. We present how the adversary can optimally allocate power across subcarriers during the sensing interval over Nakagami-m fading channels, using an optimization approach specific to this problem. We determine a worst-case optimal spoofing power allocation, when the adversary has knowledge of the system, which gives a lower bound to the average number of accessible bands for SUs under attack.\",\n \"Title: Double-layer video transmission over decode-and-forward wireless relay networks using hierarchical modulation.\\nYear: 2014\\n\\nAbstract: We consider a wireless relay network with a single source, a single destination, and a multiple relay. The relays are half-duplex and use the decode-and-forward protocol. The transmit source is a layered video bitstream, which can be partitioned into two layers, a base layer (BL) and an enhancement layer (EL), where the BL is more important than the EL in terms of the source distortion. The source broadcasts both layers to the relays and the destination using hierarchical 16-QAM. Each relay detects and transmits successfully decoded layers to the destination using either hierarchical 16-QAM or QPSK. The destination can thus receive multiple signals, each of which can include either only the BL or both the BL and the EL. We derive the optimal linear combining method at the destination, where the uncoded bit error rate is minimized. We also present a suboptimal combining method with a closed-form solution, which performs very close to the optimal. We use the proposed double-layer transmission scheme with our combining methods for transmitting layered video bitstreams. Numerical results show that the double-layer scheme can gain 2–2.5 dB in channel signal-to-noise ratio or 5–7 dB in video peak signal-to-noise ratio, compared with the classical single-layer scheme using conventional modulation.\",\n \"Title: Optimized Spoofing and Jamming a Cognitive Radio\\nYear: 2014\\n\\nAbstract: We examine the performance of a cognitive radio system in a hostile environment where an intelligent adversary tries to disrupt communications by minimizing the system throughput. We investigate the optimal strategy for spoofing and jamming a cognitive radio network with a Gaussian noise signal over a Rayleigh fading channel. We analyze a cluster-based network of secondary users (SUs). The adversary may attack during the sensing interval to limit access for SUs by transmitting a spoofing signal. By jamming the network during the transmission interval, the adversary may reduce the rate of successful transmission. We present how the adversary can optimally allocate power across subcarriers during sensing and transmission intervals with knowledge of the system, using a simple optimization approach specific to this problem. We determine a worst-case optimal energy allocation for spoofing and jamming, which gives a lower bound to the overall information throughput of SUs under attack.\",\n \"Title: Rejection of multiple narrow-band interference in both BPSK and QPSK DS spread-spectrum systems\\nYear: 1988\\n\\nAbstract: The performance of direct-sequence spread-spectrum systems using a suppression filter in the presence of multiple narrow band interference with rational spectral densities is analyzed. Both BPSK and QPSK systems are considered, and analytical expressions for both the means-square error of the filter output and the performance improvement are established. When the bandwidths of the narrow band components of the interference are all small, approximate expressions are obtained and used to provide further insight into the behavior of the system. Results are presented for the limiting case when the bandwidths approach aero (i.e. when multiple narrow band interference becomes multiple sinusoidal interference). >\",\n \"Title: Maximum-likelihood estimation of the angular position and extent of a target\\nYear: 1981\\n\\nAbstract: The maximum-likelihood estimates of the angular position and angular extent of a target relative to the boresight of a monopulse radar system is derived, and the statistics of the estimates are determined. It is shown that the moments of the estimates do not exist when the thermal noise power in the receiver is nonzero. However, conditional moments are determined which do exist, as well as conditional density and/or distribution functions.\",\n \"Title: SNR estimation in Nakagami-m fading with diversity combining and its application to turbo decoding\\nYear: 2002\\n\\nAbstract: We propose an online signal-to-noise ratio (SNR) es- timation scheme for Nakagami- fading channels with branch equal gain combining (EGC) diversity. We derive the SNR estimate based on the statistical ratio of certain observables over a block of data, and use the SNR estimates in the iterative decoding of turbo codes on Nakagami- fading channels with branch EGC diversity. We evaluate the turbo decoder performance using the SNR estimate under various fading and diversity scenarios ( and ) and compare it with the performance using perfect knowledge of the SNR and the fade amplitudes. Index Terms—Diversity, Nakagami fading, SNR estimation, turbo codes.\",\n \"Title: Multicarrier CDMA system with cochannel interference cancellation\\nYear: 1994\\n\\nAbstract: In a conventional quasi-synchronous system, synchronized users, so-called in-sync users, experience less interference than do out of sync users. The authors propose a new technique to cancel the cochannel interference for an out-of-sync user in the forward link of a cellular CDMA system. They use multicarrier direct sequence waveforms, which can yield both robustness against multipath fading and narrowband interference suppression, in addition to cochannel interference suppression\",\n \"Title: Performance of Meteor-Burst Communication Channels\\nYear: 1987\\n\\nAbstract: In this paper, we briefly describe the physical characteristics of a meteor-burst (MB) communication channel, and then present the results of an analysis showing the expected throughput and the probability of completing a given message under two different scenarios. In the first scenario, the transmitter is presumed to have knowledge (obtained by appropriate probe signals) of the entire duration of a given MB. In the second, only the starting time of each MB is known. Numerical results based on the analysis are provided, and it is shown what types of delays must be tolerated in order to achieve a given degree of reliability of having the transmitted message correctly received at its destination.\",\n \"Title: Further results on selection combining of binary NCFSK signals in Rayleigh fading channels\\nYear: 2004\\n\\nAbstract: In this paper, we provide an analytical performance comparison of various selection combining (SC) schemes for binary noncoherent frequency-shift keying (NCFSK) signals operating on independent and nonidentically distributed (i.n.d.) Rayleigh fading channels. With this motivation, we first derive the receiver structure for the optimum SC scheme, which combines one out of the available diversity branches so as to minimize the probability of bit error. We show that the optimum SC scheme chooses the diversity branch having the largest magnitude of the logarithm of the a posteriori probability ratio (LAPPR) of the transmitted information bit. We also show that: 1) the optimum noncoherent diversity receiver, for binary NCFSK signals, is equivalent to combining the LAPPRs of all the diversity branches; 2) the SC scheme proposed by Neasmith and Beaulieu is a special case of the optimum SC scheme for independent and identically distributed (i.i.d.) Rayleigh fading; and 3) for i.n.d. fading with dual diversity (i.e., ), the performance of the optimum SC scheme is the same as that of the optimum noncoherent diversity receiver, whereas the Neasmith and Beaulieu SC scheme gives the performance of the suboptimum equal gain combining receiver. Bit-error rate (BER) results show that, at BER, for i.i.d. Rayleigh fading, the proposed optimum SC scheme performs better than the existing SC schemes by 0.5-0.9 dB for and by 0.8-1.5 dB for , and performs within 0.3 dB of the optimum noncoherent diversity receiver for , and for i.n.d. Rayleigh fading with , the optimum SC scheme gives an additional gain of about 2.0 dB over the Pierce SC scheme. Further, for i.i.d. Rayleigh fading, we derive the bit-error probability expression for a selection scheme which combines three branches whose LAPPR magnitudes are the largest among the available branches. Numerical results for this selection scheme show that for at a BER of , combining the three branches with the largest LAPPR magnitudes yields almost the full performance of the optimum noncoherent diversity receiver, whereas, for , it is just about 0.2 dB away from the latter. Index Terms—Fading channels, noncoherent frequency-shift keying (NCFSK), optimum combining, selection diversity.\",\n \"Title: On the capacity of dual diversity combining schemes on correlated Rayleigh fading channels with unequal branch gains\\nYear: 2004\\n\\nAbstract: In this paper, we investigate the effect of fade correlation and the level of imbalance in the mean signal strength on the capacity of Rayleigh fading channels with dual antenna receive diversity. We consider maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SC) diversity schemes and derive expressions for the average and the outage capacities of the channel. For the case of MRC and SC schemes we obtain closed-form expressions for the average and the outage capacities, whereas efficient Gauss-Hermite quadrature rule-based expressions are provided for ECG diversity. Numerical results are provided to illustrate the capacity degradation due to channel correlation and unbalanced diversity branches.\",\n \"Title: Analysis of selection combining schemes on Rayleigh fading channels with noisy channel estimates\\nYear: 2004\\n\\nAbstract: The optimum selection combining (SC) scheme, proposed recently by Kim, requires estimation of complex channel fades on every diversity channel for minimizing the average probability of error. In this paper, we quantify the effect of imperfect channel estimation on the performance of the optimum SC receiver. By modeling the estimation errors as independent Gaussian random variables, we obtain a simple closed-form expression for the average probability of error. We also analyze a simple sub-optimum SC scheme, based on the output of the coherent matched filter alone, without requiring the knowledge of the fade amplitudes, in the presence of channel estimation errors. Finally, we provide some numerical results to illustrate the comparative performances of various SC receivers with pilot-aided minimum mean-square error (MMSE) channel estimation.\",\n \"Title: The effects of channel-estimation errors on a space-time spreading CDMA system with dual transmit and dual receive diversity\\nYear: 2004\\n\\nAbstract: The uplink of a space-time spreading code-division multiple-access system with dual transmit and dual receive antennas is analyzed with the effect of imperfect channel estimation. With the help of pilot signals, the Rayleigh multipath fading channel experienced by the transmitted signal is estimated by simple correlators, and subsequently used to coherently combine the multipath signals in a RAKE-like space-time combiner. As a system becomes more wideband, more multipaths are resolved, and the energy in each path is reduced. This reduction in signal strength causes increased estimation error and impacts the system performance. Through the derivation of the probability of error in a space-time spreading system with channel-estimation errors, this paper studies the tradeoff between diversity and estimation errors. It is shown that an optimal bandwidth exists and the optimal power allocation for the pilot signals is a function of the quality of the channel estimates.\",\n \"Title: Performance of DS/CDMA UWB communication systems in the presence of narrow-band interference and imperfect channel estimation\\nYear: 2004\\n\\nAbstract: This work considers the performance of a DS/CDMA system in the presence of narrow-band interference and imperfect channel estimation. A receiver based on MMSE channel estimation and maximum-likelihood data detection is assumed. An adaptive MMSE receiver, based on the LMS algorithm, is also explored. The performance of the DS/CDMA system is compared with that of a recently proposed UWB spectral-encoded system. The formulation and numerical results presented allow for a better understanding of the spectral overlay effects for UWB communication systems.\",\n \"Title: Capacities of FDMA/CDMA systems in the presence of phase noise and multipath Rayleigh fading\\nYear: 1998\\n\\nAbstract: The effect of phase noise on the capacities of coher- ently demodulated hybrid frequency-division multiple access/code division multiple-access (FDMA/CDMA) systems operating over a multipath Rayleigh-fading channel is investigated. Using an approximate upper bound on the bit-error rate performance, which has been derived and presented in a previous paper, the capacities of the FDMA/CDMA systems are estimated for several combinations of channel and system parameters. Simulation results are also included to show the effect of the bounding error.\",\n \"Title: Spectral-Encoded UWB Communication Systems: Real-Time Implementation and Interference Suppression\\nYear: 2005\\n\\nAbstract: This paper considers a particular implementation of an ultra-wideband communication system that uses spectral encoding as both the multiple-access scheme and the interference-suppression technique. The main advantage of this technique is that the transmitted signal spectrum can be conveniently shaped to suppress narrowband interference and to not cause noticeable interference to overlaid systems. An extensive analysis of a possible implementation of this system by using surface acoustic-wave models is presented, and general expressions for the system performance are obtained. Numerical results show that a significant improvement in the system performance is obtained when the proposed interference-suppression method is used.\",\n \"Title: Optical PPM detection with sample decision photon counting\\nYear: 2005\\n\\nAbstract: A sample-decision photon counting receiver architecture is proposed for use in optical communication systems operating in low-flux conditions such as proposed deep space optical links. The performance of this system using PPM signaling is analyzed and compared to the performance of an ideal photon counter and a slot-energy detection receiver architecture at representative operating points\",\n \"Title: Throughput-delay analysis of a multichannel wireless access protocol\\nYear: 2000\\n\\nAbstract: In this paper, we analyze the effect of bursty packet losses, caused by a correlation in the multipath fading process, on the throughput and delay performance of a multichannel wireless access protocol. equal-capacity, orthogonal, traffic channels are shared by mobile users on the uplink (mobile-to-base station link). Transmission attempts on the uplink are made based on the busy/idle status of the receivers, which is broadcast by the base station, in every slot, on the downlink (base station-to-mobile link). Following a Markov chain analysis, we derive the analytical expressions for the average per channel throughput and the mean message transfer delay. Simulation results are shown to verify the analysis. We compare the effect of Doppler bandwidth on the performance of both the basic protocol without link layer error recovery and a modified version of the protocol that employs a \\\"persist-until-success\\\" link layer retransmission strategy to recover erroneous data packets. any of these channels based on a suitable access protocol. The performance of multichannel slotted ALOHA systems, where multiple equal-capacity channels are shared by many users, has been analyzed in (7) and (8). However, these studies assumed a deterministic channel model that did not consider the effect of multipath fading on the system performance. In fact, mobile radio channels are severely affected by time-varying losses due to distance, shadowing, and multipath fading. While the variation in the losses due to distance and shadowing is relatively slow, the variation due to multipath fading is quite rapid (9), (10). The fading envelope due to multipath typically follows a Rayleigh distribution whose autocorrelation function depends on the normalized Doppler bandwidth, which in turn varies as a function of the mobile user velocity (10). In this paper, we analyze the throughput and delay performance of a multichannel wireless access protocol taking physical layer impairments into account. Specifically, we analyze the effect of bursty packet losses, caused by correlation in the multipath fading process,\",\n \"Title: Performance of an LMS type receiver for interference suppression in long code DS-CDMA on Rayleigh fading channels\\nYear: 2000\\n\\nAbstract: We consider interference suppression for direct sequence code division multiple access systems when long codes are used for spreading. In particular, we evaluate the performance of a least mean square (LMS) type adaptive receiver on AWGN and correlated Rayleigh fading channels. The receiver uses a chip matched filter followed by an adaptive equalizer structure which performs despreading and interference suppression. The receiver requires only the knowledge of the long code and timing of the desired user. The probability of the error performance of the long code LMS (LC-LMS) receiver is estimated for varying degrees of near-far ratio (NFR), mobile user speed (equivalently, the Doppler bandwidth), and long code period (expressed in number of information bits). Performance results indicate that the given adaptive receiver outperforms the conventional linear correlation receiver by a considerable margin in high NFR and low mobility (i.e., small Doppler bandwidth) scenarios\",\n \"Title: Beamforming for interference mitigation in TH impulse radio UWB systems\\nYear: 2005\\n\\nAbstract: The ability of impulse radio to resolve a large number of multipaths in a dense frequency selective channel suggests only a marginal improvement in performance by the use of multiple antennas from a diversity perspective. Furthermore, the small size of UWB receivers for in-home or sensor networking would result in a very high correlation among antenna elements, reducing even more the exploitable diversity. Therefore, we concentrate on the use of multiple antennas for interference suppression. Specifically, we investigate the performance of a quadrature receiver for impulse radio systems with multiple receive antennas and minimum-mean-square-error beamforming to combat interference\",\n \"Title: Bounds on the performance of turbo codes on Nakagami fading channels with diversity combining\\nYear: 2001\\n\\nAbstract: We derive bit error performance bounds for turbo codes on Nakagami fading channels with diversity combining. We first derive the average pairwise error probability expressions for turbo codes with maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) on Nakagami fading channels. Using the pairwise error probability expressions and the union bounding technique, we then obtain bounds on the bit error probability of turbo codes for MRC, EGC, and SC diversity schemes. We present the modified log-MAP turbo decoder for MRC, EGC, and SC, and compare the analytical bounds with simulation results for the special case of 2-antenna diversity with Nakagami parameter m=1 (i.e., Rayleigh fading). Results indicate that the EGC scheme with turbo coding performs close to MRC scheme for i.i.d Rayleigh fading\",\n \"Title: Acquisition of multicarrier spread spectrum signals with correlated Rayleigh fading among its subcarriers\\nYear: 2002\\n\\nAbstract: Multicarrier (MC) code division multiple access (CDMA) is an attractive way of implementing wideband CDMA systems while being backward-compatible with the existing narrowband CDMA systems. Initial acquisition in MC-CDMA has been studied for the case where the subcarriers experience independent fades. For many of scenarios, the assumption about the independence is unreasonable. We relax this assumption, and employ a realistic model for frequency correlation. We obtain an optimum receiver for initial acquisition that accounts for the frequency correlation, and present a technique for the analysis of this receiver. Finally, we study, by simulation, the tradeoff between the diversity gain available and noncoherent loss incurred as the number of subcarriers is increased.\",\n \"Title: Statistical channel knowledge-based optimum power allocation for relaying protocols in the high SNR regime\\nYear: 2007\\n\\nAbstract: We are concerned with transmit power optimization in a wireless relay network with various cooperation protocols. With statistical channel knowledge (in the form of knowledge of the fading distribution and the path loss information across all the nodes) at the transmitters and perfect channel state information at the receivers, we derive the optimal power allocation that minimizes high signal-to-noise ratio (SNR) approximations of the outage probability of the mutual information (MI) with amplify-and-forward (AF), decode-and-forward (DF) and distributed space-time coded (DSTC) relaying protocols operating over Rayleigh fading channels. We demonstrate that the high SNR approximation-based outage probability expressions are convex functions of the transmit power vector, and the nature of the optimal power allocation depends on whether or not a direct link between the source and the destination exists. Interestingly, for AF and DF protocols, this allocation depends only on the ratio of mean channel power gains (i.e., the ratio of the source-relay gain to the relay-destination gain), whereas with a DSTC protocol this allocation also depends on the transmission rate when a direct link exists. In addition to the immediate benefits of improved outage behavior, our results show that optimal power allocation brings impressive coding gains over equal power allocation. Furthermore, our analysis reveals that the coding gain gap between the AF and DF protocols can also be reduced by the optimal power allocation.\",\n \"Title: Decoding on Graphs: LDPC-Coded MISO Systems and Belief Propagation\\nYear: 2008\\n\\nAbstract: This paper proposes a new approach for decoding LDPC codes over MISO channels. Since in an nT times 1 MISO system with a modulation of alphabet size 2M, nT transmitted symbols are combined and produce one received symbol at the receiver, we propose considering the LDPC-coded MISO system as an LDPC code over 2MnT-ary alphabet. Consequently, we propose a modified Tanner graph to introduce belief propagation for decoding MISO-LDPC systems. As a result, the MISO symbol detection and binary LDPC decoding steps are merged into a single message passing decoding. We also propose an efficient method that significantly reduces the complexity of belief propagation decoding in MISO-LDPC systems. Furthermore, we show that our proposed decoder outperforms the conventional decoder for short length LDPC codes in unknown channel scenarios.\",\n \"Title: Improved Linear Parallel Interference Cancellers\\nYear: 2008\\n\\nAbstract: In this paper, taking the view that a linear parallel interference canceller (LPIC) can be seen as a linear matrix filter, we propose new linear matrix filters that can result in improved bit error performance compared to other LPICs in the literature. The motivation for the proposed filters arises from the possibility of avoiding the generation of certain interference and noise terms in a given stage that would have been present in a conventional LPIC (CLPIC). In the proposed filters, we achieve such avoidance of the generation of interference and noise terms in a given stage by simply making the diagonal elements of a certain matrix in that stage equal to zero. Hence, the proposed filters do not require additional complexity compared to the CLPIC, and they can allow achieving a certain error performance using fewer LPIC stages. We also extend the proposed matrix filter solutions to a multicarrier DS-CDMA system, where we consider two types of receivers. In one receiver (referred to as Type-I receiver), LPIC is performed on each subcarrier first, followed by multicarrier combining (MCC). In the other receiver (called Type-II receiver), MCC is performed first, followed by LPIC. We show that in both Type-I and Type-II receivers, the proposed matrix filters outperform other matrix filters. Also, Type-II receiver performs better than Type-I receiver because of enhanced accuracy of the interference estimates achieved due to frequency diversity offered by MCC.\",\n \"Title: Optimum transmit-receive beamforming with noisy channel estimates for correlated MIMO Rayleigh channels\\nYear: 2008\\n\\nAbstract: In this paper, we design jointly optimum transmitter and receiver beamforming structures in correlated MIMO Rayleigh fading channels with noisy channel estimates, and evaluate their performance through a closed-form expression for the probability of error. At the receiver, an estimate of the channel is obtained based on the transmitted pilot symbols. The knowledge of the estimate is then made available to the transmitter through a feedback channel. It is assumed that spatial correlation exists, either at the transmitter or at the receiver. A new exact closed-form expression for the probability of error is derived and the joint effects of diversity order and channel estimation accuracy on system performance are analyzed.\",\n \"Title: Iterative Channel Decoding of FEC-Based Multiple-Description Codes\\nYear: 2012\\n\\nAbstract: Multiple description coding has been receiving attention as a robust transmission framework for multimedia services. This paper studies the iterative decoding of FEC-based multiple description codes. The proposed decoding algorithms take advantage of the error detection capability of Reed-Solomon (RS) erasure codes. The information of correctly decoded RS codewords is exploited to enhance the error correction capability of the Viterbi algorithm at the next iteration of decoding. In the proposed algorithm, an intradescription interleaver is synergistically combined with the iterative decoder. The interleaver does not affect the performance of noniterative decoding but greatly enhances the performance when the system is iteratively decoded. We also address the optimal allocation of RS parity symbols for unequal error protection. For the optimal allocation in iterative decoding, we derive mathematical equations from which the probability distributions of description erasures can be generated in a simple way. The performance of the algorithm is evaluated over an orthogonal frequency-division multiplexing system. The results show that the performance of the multiple description codes is significantly enhanced.\",\n \"Title: Channel Model and Performance Analysis of QAM Multiple Antenna Systems at 60-GHz in the Presence of Human Activity\\nYear: 2011\\n\\nAbstract: In this paper, a 60-GHz channel model that incorporates the presence of human activity, and which is an extension of the standard channel model proposed by the IEEE 802.15.3c group, is presented. In the presence of human activity, various measurement results show that the attenuation due to human blockage can be 20 dB or more, and thus is non-negligible. Various measurement results in the literature are used to determine the distribution of the shadowing attenuation caused by human blockage. A multiuser single-carrier system with a single receiver is considered, and system performance in the presence of blockage because of human activity is evaluated. Numerical results show that the 60-GHz system can incur a large degradation in bit error rate due to human blockage.\",\n \"Title: Progressive Source Transmissions Using Joint Source-Channel Coding and Hierarchical Modulation in Packetized Networks\\nYear: 2009\\n\\nAbstract: With Unequal Error Protection (UEP), more important symbols are given greater protection against channel errors than are less important symbols. The protection can be accomplished by various methods, including joint source-channel coding (JSCC) and hierarchical modulation. In this paper, a robust progressive source transmission system using forward error correction (FEC) and a bits-to-symbol assignment methodology that provides UEP is proposed. UEP is not only provided by hierarchical modulation but also by the packetization methodology combined with channel coding. It is demonstrated by simulation that our system improves performance compared to an Equal Error Protection (EEP) technique and to a baseline JSCC-only mechanism.\",\n \"Title: Variance-Aware Adaptive Modulation for OFDM-Based Multiple Description Progressive Image Transmission\\nYear: 2010\\n\\nAbstract: Average throughput maximization has commonly been used as an alternative to image or video average distortion minimization. However, as the throughput-distortion curve is non-linear, throughput maximization can be very different from distortion minimization if the variance of the throughput is large. Under high channel quality variability, the variance of the throughput will be high. Multiple description coding with unequal error protection is a promising technique for the transmission of progressive images when there exists a high variability of the channel conditions. In this paper, we consider both the variance and the average of the throughput when deciding the constellation size for adaptive modulation in an OFDM system used for transmitting progressively-coded images with multiple description coding. Simulation results show that in an adaptive modulated image transmission system, taking into account both moments of the throughput achieves better performance than a system considering average throughput alone.\",\n \"Title: Subcarrier mapping based on slice visibility for video transmission over OFDM channels\\nYear: 2012\\n\\nAbstract: We address channel code rate optimization for transmission of non-scalable coded video sequences over orthogonal frequency division multiplexing networks for scenarios with arbitrary mobility. A slice loss visibility (SLV) model is used to evaluate the visual importance of each H.264 slice. In particular, taking into account both the visibility scores available from the bitstream and the channel state information, we optimize the channel code rate for each GOP and the mapping of video slices within 2-D time-frequency resource blocks, in order to better protect more visually important slices. Results demonstrate that the proposed algorithm outperforms baseline ones which do not take into account the SLV in the video transmission.\",\n \"Title: Optimized receiver design for decode-and-forward relays using hierarchical modulation\\nYear: 2013\\n\\nAbstract: We consider a wireless relay network with a single source, a single destination, and multiple relays. The relays are half-duplex and use the decode-and-forward protocol. The transmit source is a layered bitstream, which can be partitioned into two layers. The source broadcasts both layers to all the relays and the destination using hierarchical 16-QAM. Each relay detects and transmits successfully decoded layers to the destination using either hierarchical 16-QAM or QPSK using orthogonal channels. We derive the optimal linear-combining receiver at the destination, where the uncoded bit error rate is minimized. We also present a suboptimal combining method with a closed-form solution, which performs very close to the optimal. Numerical results show that the two-layer scheme outperforms the classical one-layer scheme using conventional modulation.\",\n \"Title: Coded Hierarchical Modulation for Wireless Progressive Image Transmission\\nYear: 2011\\n\\nAbstract: A robust coded scheme for progressive multimedia transmission is proposed for additive white Gaussian noise, flat Rayleigh fading channels, and frequency-selective channels using different unequal error protection methods in combination. Hierarchical modulation is coupled with a packetization/combining strategy and an efficient channel encoder consisting of a cyclic redundancy check outer coder concatenated with an inner rate-compatible punctured convolutional coder. Distortion-optimal hierarchical parameters are jointly chosen with the set of channel coding parameters on a packet-switched wireless network with fixed length packets. A lower bound for the performance improvement of the proposed system is derived and shown to give significant gains at lower packet sizes and higher transmission rates. The proposed system is also shown to outperform several existing schemes for realistic wireless channels.\",\n \"Title: Error Rate for PSK and QAM Modulations for Non-Ideal OFDM Systems with Noisy Channel Estimates and Receive Diversity\\nYear: 2011\\n\\nAbstract: This paper characterizes the SER for a non-ideal OFDM system with either M-PSK or M-QAM constellations operating over a frequency-selective, time-varying, Rayleigh fading channel. The imperfections that we consider are inter-carrier interference (ICI) and/or inter-symbol interference (ISI), imperfect time and frequency synchronization, and noisy channel estimates. We consider an MRC receiver with L diversity branches. We present SER characterizations with and without ISI, and show that the effect of ISI, especially for higher order modulation schemes, e.g., 8PSK and above, can be very severe, irrespective of the number of diversity branches.\",\n \"Title: Channel estimation for non-ideal OFDM systems\\nYear: 2010\\n\\nAbstract: Studies of channel estimation techniques for OFDM systems often assume idealized conditions such as a cyclic prefix (CP) long enough to absorb the entire channel delay spread, or perfect time and frequency synchronization at the receiver. This paper studies the impact of removing these assumptions. We characterize the mean square error (MSE) of various linear channel estimation methods, and we derive analytical expressions for the BER performance. The derivations are kept generic so that they apply to both time-division and frequency-division multiplexing of the pilot signal and the data subcarriers. The analysis is specialized to the BER performance characterization of OFDM-based UWB systems for different realistic channel estimation methods with residual time and frequency errors. The effect of inter-carrier interference (ICI) on channel estimation is shown to be small. However, inter-symbol interference (ISI) severely impacts the quality of the channel estimates and hence can yield a large (>2 dB) data demodulation performance degradation.\",\n \"Title: Optimal Multiplexed Hierarchical Modulation for Unequal Error Protection of Progressive Bit Streams\\nYear: 2009\\n\\nAbstract: Progressive image and scalable video have gradual differences of importance in their bitstreams, which can benefit from multiple levels of unequal error protection (UEP). Though hierarchical modulation has been intensively studied as an UEP approach for digital broadcasting and multimedia transmission, methods of achieving a large number of UEP levels have rarely been studied. In this paper, we propose a multilevel UEP system using multiplexed hierarchical quadrature amplitude modulation (QAM) for progressive transmission over mobile radio channels. We suggest a specific way of multiplexing, and prove that multiple levels of UEP are achieved by the suggested method. When the BER is dominated by the minimum Euclidian distance, we derive an optimal multiplexing approach which minimizes both the average and peak powers. An asymmetric hierarchical QAM which reduces the peak-to-average power ratio (PAPR) without performance loss is also proposed. Numerical results show that the performance of progressive transmission over Rayleigh fading channels is significantly enhanced by the proposed UEP systems.\",\n \"Title: Optimization of generalized LT codes for progressive image transfer\\nYear: 2012\\n\\nAbstract: Rateless codes allow a user to incrementally send additional redundancy, so they can be useful for heterogeneous and time-varying networks for which the choice of redundancy level in advance is difficult. Rateless codes are an attractive application layer forward error correction solution due to their flexibility and capacity-approaching performance. The original rateless codes were developed for the delivery of equally important information. In many multimedia applications, some data symbols are more important than others. Unequal error protection (UEP) designs are attractive solutions for such transmissions. However previous UEP rateless code designs were aimed for coarsely layered sources and might exhibit poor performance for fine-grained progressive coding. The main objective of this paper is to introduce a more generalized coding scheme, parameters of which can be tailored for progressive multimedia transmission. We present the optimization of a generalized rateless code using two different progressive source transmission protocols. Proposed coding scheme is shown to exhibit better unequal protection and recovery time properties than other published results.\",\n \"Title: Throughput and Delay Analysis for Real-Time Applications in Ad-Hoc Cognitive Networks\\nYear: 2010\\n\\nAbstract: We consider a simple ad-hoc cognitive scenario with two data up-links, one licensed to use the spectral resource (primary) and the other unlicensed (secondary or cognitive). It is assumed that the cognitive link accesses the channel only when the channel is sensed idle. An ON-OFF channel model is used for the primary link, where traffic statistical characteristics are taken into account. A closed-form expression for the signal-to noise-plus interference (SINR) statistics of the cognitive nodes is derived that can be used for estimating the network performance. Moreover, a M/G/1 queueing model is exploited for deriving a simple expression for the average packet delay. Finally, a MAC strategy based on a channel-and-queue aware scheduling is introduced.\",\n \"Title: Joint source-channel coding of 3D video using multiview coding\\nYear: 2013\\n\\nAbstract: We consider the joint source-channel coding problem of a 3D video transmitted over an AWGN channel. The goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under two constraints: the quality of the primary view and the quality of the secondary view must be greater than or equal to a predetermined threshold at the receiver. The quality is measured in terms of the expected PSNR of an entire decoded group of pictures. A MVC (multiview coding) encoder is used as the source encoder, and rate compatible punctured turbo codes are utilized for protection of the encoded 3D video over the noisy channel. Equal error protection and unequal error protection are compared for various 3D video sequences and noise levels.\",\n \"Title: Device-To-Device Assisted Video Transmission\\nYear: 2013\\n\\nAbstract: To increase spectrum efficiency, researchers envision a device-to-device (D2D) communication system in which a closely located mobile device pair may share the same spectrum with a cellular user. By opportunistically choosing the frequency, the D2D pair may increase the spectrum efficiency in terms of data rate per Hertz, at the price of additional interference to that cellular user. In previous models, users either stop cellular transmission and switch to D2D transmission or vice versa. However, if the cell is fully loaded, a D2D pair will not be able to switch back to the conventional mode because no extra resource is available. In this paper, we propose a D2D assisted model, where a D2D link is enabled to assist transmission, while keeping the conventional cellular transmission. In this way, the D2D link can be turned on and off according to the link quality. We also propose a PHY-layer study for the transmission scheme in such a way that the system throughput and the video reception quality is always improved compared to a conventional link.\",\n \"Title: Video cognitive radio networks for tactical scenarios.\\nYear: 2016\\n\\nAbstract: We examine the performance of uplink video transmission over a mobile cognitive radio (CR) system operating in a hostile environment where an intelligent adversary tries to disrupt communications. We investigate the optimal strategy for spoojing, desynchronizing and jamming a cluster-based CR network with a Gaussian noise signal, over a Rayleigh fading channel. The adversary can limit access for secondary users (SUs) by either transmitting a spoojing signal in the sensing interval, or a desynchronizing signal to disrupt code acquisition by SUs or the cluster head. By jamming the network during the transmission interval, the adversary can reduce the rate of successful transmission. We also propose cross-layer resource allocation algorithms and evaluate their performance under disruptive attacks.\",\n \"Title: Resource Allocation for Multicarrier D2D Video Transmission Based on Exact Symbol Error Rate.\\nYear: 2016\\n\\nAbstract: We consider centralized cross-layer resource allocation for a device-to-device (D2D) video transmission system, given knowledge of the channel state information and the rate distortion information of the video streams, and propose an iterative algorithm for subcarrier assignment and power allocation. In the resource allocation, the performance improvement by applying the exact symbol error rate (SER) is compared with the conventional signal-to-interference-plus-noise-ratio (SINR) based SER evaluation method that uses a Gaussian approximation (GA) for the aggregated interference. An exact SER expression for a D2D system using multicarrier bandlimited QAM is derived and then used in the resource allocation algorithm. Bit-level simulations for different numbers of D2D pairs demonstrate a considerable improvement on user capacity and video peak signal-to-noise ratio by incorporating the proposed SER expression compared to the GA.\",\n \"Title: Optimization of Scalable Broadcast for a Large Number of Antennas.\\nYear: 2017\\n\\nAbstract: In this paper, for a system incorporating a large number of antennas, we address the optimal space-time coding of multimedia scalable sources, which require unequal target error rates in their bitstream. First, in terms of the number of antennas, we analyze the behavior of the crossover point of the outage probability curves for the vertical Bell Laboratories space-time (V-BLAST) architecture with...\",\n \"Title: Spatially Scalable Video Broadcasting In Multiple Antenna Systems\\nYear: 2016\\n\\nAbstract: We propose an efficient multiple-input multipleoutput (MIMO) video broadcasting technique with low computational complexity that well serves different types of users residing inside the service area of a base station. We consider a video broadcasting scenario in which heterogeneous users with different display resolutions, different operating bit rates, and different numbers of receive antennas are present. Our proposed scheme adopts spatially scalable video coding, and makes use of both spatial diversity and spatial multiplexing techniques. We compare the performance of our proposed scheme with that of a non-scalable video transmission scheme. Simulation results show that our proposed video broadcasting scheme significantly outperforms the non-scalable video broadcasting strategy. The performance improvement is observed for both different types of users we consider.\",\n \"Title: Subcarrier Assignment and Power Allocation for Device-to-Device Video Transmission in Rayleigh Fading Channels.\\nYear: 2017\\n\\nAbstract: Subcarrier assignment and power allocation for device-to-device (D2D) video transmission using a filter bank multicarrier waveform in a Rayleigh fading environment are investigated. We analyze the co-channel interference between D2D pairs, and propose a cross-layer algorithm with a subcarrier assignment outer loop and a power allocation inner loop, which aims to optimize the overall video quality....\",\n \"Title: Sensing Disruption with Estimation Uncertainty.\\nYear: 2017\\n\\nAbstract: In this paper, the sensing disruption for a power limited adversary with estimation uncertainty is formulated and analyzed. The estimation uncertainty of the adversary is modeled in terms of its probability of false alarm in vacant bands and the probability of detection in busy bands. The strategy for the adversary is obtained by maximizing the sum of the conditional probabilities of false detection within the spectral range of interest, conditioned on the adversary's estimated spectrum usage status. The proposed algorithm is shown to be significantly more robust than conventional algorithms. It is shown in simulation results that, as the adversary's power budget increases, the proposed algorithm asymptotically approaches the performance upper bound when the adversary has perfect information on the spectrum usage status.\",\n \"Title: Delay allocation between source buffering and interleaving for wireless video.\\nYear: 2016\\n\\nAbstract: One fundamental tradeoff in the cross-layer design of a communications system is delay allocation. We study delay budget partitioning in a wireless multimedia system between two of the main components of delay: the queuing delay in the source encoder output buffer and the delay caused by the interleaver. In particular, we discuss how to apportion the fixed delay budget between the source encoder and the interleaver given the channel characteristics, the video motion, the delay constraint, and the channel bit rate.\",\n \"Title: Cross-Layer Resource Allocation Using Video Slice Header Information for Wireless Transmission Over LTE.\\nYear: 2018\\n\\nAbstract: In this paper, cross-layer resource allocation methods for wireless video transmission are proposed. We propose two practical metrics to measure the relative importance of each forward error correction (FEC) block to the user's quality of experience. They can be obtained from the header information, and require no overhead bits or amendment of the header format of the existing standard video codec...\",\n \"Title: Optimal Sensing Disruption: A Generalized Framework for a Power-Limited Adversary\\nYear: 2019\\n\\nAbstract: A generalized framework of spectrum sensing disruption for a power-limited adversary is proposed in this paper. In the literature, a conventional sensing attack typically assumes that the adversary has perfect knowledge of the spectral usage status. The framework in this paper considers a more general case where there are uncertainties in the estimates at the adversary. These uncertainties are modeled utilizing the probability of detection and the probability of false alarm. Then, the sum of the conditional probabilities of false detection at the secondary within the spectral range of interest, conditioned on the adversary’s estimated spectrum usage status, is maximized. It is shown that the optimal sensing attack, given perfect estimation is a special case of the proposed framework. When the adversary has perfect spectrum usage information, this framework reduces to a previously demonstrated optimal sensing disruption. When the adversary has imperfect information on the spectral status, the proposed framework is significantly more robust than conventional sensing attacks. Further, when the adversary’s power budget increases, it asymptotically approaches the sensing disruption performance upper bound.\",\n \"Title: Robustness of Deep Modulation Recognition under AWGN and Rician Fading\\nYear: 2018\\n\\nAbstract: We study the robustness of modulation recognition using deep neural networks. This is of critical importance for applying deep learning for radio modulation classification, because wireless propagation conditions could vary significantly under different communication environments. We compare the performance of radio modulation recognition using data and using expert features. While deep modulation recognition using data has been proposed in existing literature since it achieves better performance than crafted expert features, our results indicate that using expert features yields significantly more robustness.\",\n \"Title: Joint Channel Estimation and Error Correction for Finite-State Markov Channels Using Polar Codes.\\nYear: 2018\\n\\nAbstract: A joint channel estimation and channel coding scheme is presented for finite-state Markov channels using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding algorithm and computes decoding metrics averaged over the statistical behavior of the Markov channel. By adapting list decoding (without any inner code), channel estimation and decoding steps can be performed iteratively to boost the reliability of channel estimation as well as error correction. In order to improve the performance even further, a new pilot transmission scheme is developed that utilizes the structure of polar codes and sends pilot symbols along with code symbols. This construction can be viewed as a new family of shortened polar codes that can be of independent interest. Simulation results demonstrate the benefit of the proposed approach compared to existing solutions.\",\n \"Title: Performance analysis of TCM with generalized selection combining on Rayleigh fading channels.\\nYear: 2002\\n\\nAbstract: We derive the computational cutoff rate, R/sub 0/, for coherent trellis-coded modulation (TCM) schemes on independent identically distributed (i.i.d.) Rayleigh fading channels with (K, L) generalized selection combining (GSC) diversity, which combines the K paths with the largest instantaneous signal-to-noise ratios (SNR) among the L available diversity paths. The cutoff rate is shown to be a simple function of the moment generating function (MGF) of the SNR at the output of the (K, L) GSC receiver. We also derive the union bound on the bit error probability of TCM schemes with (K, L) GSC in the form of a simple, finite integral. The effectiveness of this bound is verified through simulations.\",\n \"Title: Joint Partial-Time Partial-Band Jamming of a Multicarrier DS-CDMA System in a Fading Environment.\\nYear: 2018\\n\\nAbstract: The impact of joint partial-band, partial-time jamming on a multi-carrier asynchronous DS-CDMA system in a Rayleigh fading environment is studied. Two types of partial-time jamming are studied: equal probability jamming per symbol, and burst jamming. An easy to evaluate upper bound using the Chernoff bound is provided and compared to simulation results.\",\n \"Title: Resource Allocation for Multicarrier Device-to-Device Video Transmission: Symbol Error Rate Analysis and Algorithm Design.\\nYear: 2017\\n\\nAbstract: In resource allocation for a device-to-device (D2D) video transmission system, the performance improvement by applying the exact symbol error rate (SER) is compared with the conventional signal-to-interference-plus-noise-ratio-based SER evaluation method that uses a Gaussian approximation (GA) for the aggregated interference. An analytical SER expression for a D2D system using multicarrier bandlim...\",\n \"Title: Joint Channel Estimation and Coding Over Channels With Memory Using Polar Codes\\nYear: 2021\\n\\nAbstract: A joint channel estimation and channel coding scheme is presented for channels with memory using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding procedure and computes decoding metrics averaged over the sta...\"\n]","isConversational":false},"profile_size":{"kind":"number","value":138,"string":"138"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":266,"string":"266"}}},{"rowIdx":267,"cells":{"question_id":{"kind":"string","value":"Sean W Smith"},"question":{"kind":"string","value":"Generate an abstract for the title \"Batch Pairing Delegation\" using the following items: 1. Pairing-based cryptography\n2. Pairing delegation\n3. Batch pairing delegation\n4. Security of proposed protocols\n5. Trusted computing with pairing delegation"},"answer":{"kind":"string","value":"Pairing-based cryptography (PBC) has enabled the construc- tion of many cryptographic protocols. However, there are scenarios when PBC is too heavyweight to use, such as when the computing devices are resource-constrained. Pairing delegation introduced in (19) provides a solution by offloading the computation to more powerful entities. In this paper, we introduce the concept of, and construct several pro- tocols for, batch pairing delegation, which offers significantly improved efficiency over multiple runs of state-of-the-art (non-batch) delegation protocols. We prove the security of our proposed protocols in the model we formalized for batch pairing delegation. Also, we have implemented our protocols in software for experimentation. Moreover, we argue that the secure delegation of pairing computation, batched or not, requires different protocols depending on the semantic meaning of the pairings. We propose a taxonomy that classifies pairings into seven types to assist in choosing the right delegation protocol. Finally, we propose a novel application of pairing delegation in trusted computing — we show how pairing delegation can be leveraged to build a secure coprocessor for pairing computation more cost-effectively."},"correct_answer":{"kind":"string","value":"Pairing-based cryptography (PBC) has enabled the construc- tion of many cryptographic protocols. However, there are scenarios when PBC is too heavyweight to use, such as when the computing devices are resource-constrained. Pairing delegation introduced in (19) provides a solution by offloading the computation to more powerful entities. In this paper, we introduce the concept of, and construct several pro- tocols for, batch pairing delegation, which offers significantly improved efficiency over multiple runs of state-of-the-art (non-batch) delegation protocols. We prove the security of our proposed protocols in the model we formalized for batch pairing delegation. Also, we have implemented our protocols in software for experimentation. Moreover, we argue that the secure delegation of pairing computation, batched or not, requires different protocols depending on the semantic meaning of the pairings. We propose a taxonomy that classifies pairings into seven types to assist in choosing the right delegation protocol. Finally, we propose a novel application of pairing delegation in trusted computing — we show how pairing delegation can be leveraged to build a secure coprocessor for pairing computation more cost-effectively."},"documents":{"kind":"list like","value":["Title: PorKI: Making User PKI Safe on Machines of Heterogeneous Trustworthiness\nYear: 2005\n\nAbstract: As evidenced by the proliferation of phishing attacks and keystroke loggers, we know that human beings are not wellequipped to make trust decisions about when to use their passwords or other personal credentials. Public key cryptography can reduce this risk of attack, because authentication using PKI is designed to not give away sensitive data. However, using private keys on standard platforms exposes the user to \"keyjacking\"; mobile users wishing to use keypairs on an unfamiliar and potentially untrusted workstation face even more obstacles. In this paper we present the design and prototype of PorKI, a software application for mobile devices that offers an alternative solution to the portable key problem. Through the use of temporary keypairs, proxy certificates, and wireless protocols, PorKI enables a user to employ her PKI credentials on any Bluetoothenabled workstation, including those not part of her organization's network, and even those that might be malicious. Moreover, by crafting XACML policy statements that limit the key usage to the workstation's trustworthiness level, and inserting these statements into extensions of the proxy certificates, PorKI provides the user or the relying party with the ability to limit the amount of trust that can be put in the temporary keypair used on that workstation, and thus the scope of a potential compromise.","Title: PEACHES and Peers\nYear: 2008\n\nAbstract: How to distribute resource locators is a fundamental problem in PKI. Our PKI Resource Query Protocol (PRQP), recently presented at IETF, provides a standard method to query for PKI resources locators. However the distribution of locators across PKIs is still an unsolved problem. In this paper, we propose an extension to PRQP in order to distribute\n PRQP messages over a Peer-to-Peer (P2P) network. In this work, we combine PRQP with Distributed Hash Tables (DHTs) to efficiently distribute contents over a dynamic P2P overlay network. In particular we present the PEACH protocol and a PEACH Enabled System (PEACHES) which are specifically targeted toward solving the PKI resources discovery problem. Our work enhances interoperability between\n existing PKIs and allows for easy configuration of applications, thus augmenting usability of PKI technology.","Title: Api-do: Tools for Exploring the Wireless Attack Surface in Smart Meters\nYear: 2012\n\nAbstract: Security will be critical for the wireless interface offered by soon-to-be-ubiquitous smart meters -- since if not secure, this technology will provide an remotely accessible attack surface distributed throughout many homes and businesses. However, history shows that new network interfaces remained brittle and vulnerable (although believed otherwise) until security researchers could thoroughly explore their attack surface. Unfortunately, for the majority of currently available smart meter wireless networking solutions, we are still in that pre-exploration phase, \"closed\" radio stacks with proprietary features impede exploration by posing multiple hardware and software obstacles to standard network attack surface exploration techniques. In this paper, we address this problem by presenting open and extensible software tools for 802.15.4-based proprietary stacks that work on commodity digital radio platforms. We hope this contribution advances the state of the art beyond the pre-exploration tipping point, and toward real security.","Title: Modeling and evaluation of certification path discovery in the emerging global PKI\nYear: 2006\n\nAbstract: Establishing trust on certificates across multiple domains requires an efficient certification path discovery algorithm. Previously, small exmaples are used to analyze the performance of certification path discovery. In this work, we propose and implement a simulation framework and a probability search tree model for systematic performance evaluation. Built from measurement data collected from current PKI systems in development and deployment over more than 10 countries, our model is (to the best of our knowledge) the largest simulated PKI architecture to-date.","Title: Small, stupid, and scalable: secure computing with faerieplay\nYear: 2010\n\nAbstract: How can Agnes trust a computation C occurring at Boris's computer? In particular, how can Agnes can trust that C is occurring without Boris even being able to observe its internal state? One way is for Agnes to house C in a strong tamper-protected secure coprocessor at Boris's site. However, this approach is not scalable: neither in terms of computation - once C gets larger than the coprocessor, it becomes vulnerable to Boris again - nor in terms of cost. In this paper, we report on our Faerieplay project: rather than worrying about the limited size of a secure coprocessor, we try to make it as small as possible, with limited RAM and CPU. We start with the Fairplay work of Malkhi et al on implementing Yao's blinded-circuit solution to secure multiparty computation with software - this permits Agnes to trust C, but is too inefficient for all but small C. We then use our own prior work on using trusted third parties for practical Private Information Retrieval to design and prototype tiny trusted third parties (TTTPs) that substantially reduce the overhead involved in blind circuit evaluation.","Title: The dartmouth green grid\nYear: 2005\n\nAbstract: The Green Grid is an ambitious project to create a shared high performance computing infrastructure for science and engineering at Dartmouth College. The Green Grid was created with the support of the Dean of the Faculty of Arts & Sciences to promote collaborative computing for the entire Dartmouth community. We will share our design for building campus grids and experiences in Grid-enabling applications from several academic departments.","Title: The cake is a lie: privilege rings as a policy resource\nYear: 2009\n\nAbstract: Components of commodity OS kernels typically execute at the same privilege level. Consequently, the compromise of even a single component undermines the trustworthiness of the entire kernel and its ability to enforce separation between user-level processes. Reliably containing the extent of a compromised kernel component is a problem to which few practical solutions exist. While many approaches have been proposed to reduce the need to trust large portions of the kernel, most of these approaches represent exotic reorganizations of the hardware or OS kernel that are either not applicable to commodity systems or are relatively complex and difficult to debug in their own right (e.g., microkernels). We propose simple, natural modifications to commodity---x86---hardware that enable vertical isolation down through the kernel without the use of virtualization or major OS rewrites; specifically, extending and reinterpreting the x86 segmentation mechanism, extending the existing Current Privilege Level and Descriptor Privilege Level fields. We believe our proposal is a compelling alternative to traditional virtualization because the hardware virtualizes permissions, not I/O.","Title: VM-based security overkill: a lament for applied systems security research\nYear: 2010\n\nAbstract: Virtualization has seen a rebirth for a wide variety of uses; in our field, systems security researchers routinely use it as a standard tool for providing isolation and introspection. Researchers' use of virtual machines has reached a level of orthodoxy that makes it difficult for the collective wisdom to consider alternative approaches to protecting computation. We suggest that many scenarios exist where virtual machines do not provide a suitable tool or appropriate security properties. We analyze the use of virtual machines in the systems security space and we highlight other work that questions the current (ab)uses of virtualization. The takeaway message of this paper is that 'self-protection' mechanisms still represent an interesting and viable path of research. At some point, hypervisors (or whatever the lowest layer of software, firmware, or programmable hardware is) must rely on detection and protection mechanisms embedded within themselves.","Title: Protecting Client Privacy with Trusted Computing at the Server\nYear: 2005\n\nAbstract: Current trusted-computing initiatives usually involve large organizations putting physically secure hardware on user machines, potentially violating user privacy. Yet, it's possible to exploit robust server-side secure hardware to enhance user privacy. Two case studies demonstrate using secure coprocessors at the server.","Title: Attribute-Based Publishing with Hidden Credentials and Hidden Policies\nYear: 2007\n\nAbstract: With Hidden Credentials Alice can send policy- encrypted data to Bob in such a way that he can decrypt the data only with the right combination of credentials. Alice gains no knowledge of Bob's credentials in the process, and hence the name \"Hidden Credentials.\" Research on Hidden Credential systems has focused on messages sent to single recipients, where the sender needs to know the recipient's pseudonym beforehand, and on Hidden Policies, where Bob learns as little information as possible about Alice's pol- icy for decrypting the message. Current schemes provide weak policy privacy — with non-interactive schemes, the recipient can learn parts of the policy, and with interac- tive schemes based on secure multiparty computation, a user can try different sets of credentials as input to gain knowledge of the policy after repeated decryption attempts. Furthermore, existing schemes do not support policies with negations efficiently. For example, a policy stating \"Bob is not a student\" is hard to enforce since Bob can simply withhold, or not use, his student credential. We propose a system called PEAPOD (Privacy- Enhanced Attribute-based Publishing Of Data) that pro- vides the following properties: (1) Users can securely pub- lish data protected by attribute-based policies to multiple possible recipients without requiring interaction between senders and receivers. This is achieved by using a semi- trusted server. (2) The plaintext message and the policy are completely hidden from the server. (3) Any recipient, intended or not, learns no other information about a mes- sage's policy beyond the number of clauses in policy that were satisfied. Furthermore the recipient is forced to use allof his or her issued credentials for decryption, and there- fore cannot mount inference attacks by trying to decrypt the","Title: ABUSE: PKI for real-world email trust\nYear: 2009\n\nAbstract: Current PKI-based email systems (such as X.509 S/MIME and PGP/ MIME) potentially enable a recipient to determine a name and organizational affiliation of the sender. This information can suffice for a trust decision when the recipient already knows the sender--but how can a recipient decide whether or not trust email from a new correspondent? Current systems are not expressive enough to capture the real ways that trust flows in these sorts of scenarios. To solve this problem, we begin by applying concepts from social science research to a variety of such cases from interesting application domains; primarily, crisis management in the North American power grid. We have examined transcripts of telephone calls made between grid management personnel during the August 2003 North American blackout and extracted several different classes of trust flows from these real-world scenarios. Combining this knowledge with some design patterns from HCISEC, we develop criteria for a system that will enable humans apply these same methods of trust-building in the digital world. We then present the design and prototype of Attribute-Based, Usefully Secure Email (ABUSE)--and present experimental evaluation showing that it solves the problem.","Title: Katana: A Hot Patching Framework for ELF Executables\nYear: 2010\n\nAbstract: Despite advances in software modularity, security, and reliability, offline patching remains the predominant form of updating or protecting commodity software. Unfortunately, the mechanics of hot patching (the process of upgrading a program while it executes) remain understudied, even though such a capability offers practical benefits for both consumer and mission-critical systems. A reliable hot patching procedure would serve particularly well by reducing the downtime nec- essary for critical functionality or security upgrades. Yet, hot patching also carries the risk - real or perceived - of leaving the system in an inconsistent state, which leads many owners to forego its benefits as too risky. In this paper, we propose a novel method for hot patching ELF binaries that supports (a) synchronized global data and code updates and (b) reasoning about the results of applying the hot patch. We propose a format, which we call a Patch Object, for encoding patches as a special type of ELF relocatable object file. Our tool, Katana, automatically creates these patch objects as a by-product of the standard source build process. Katana also allows an end-user to apply the Patch Objects to a running process. In essence, our method can be viewed as an extension of the Application Binary Interface (ABI), and we argue for its inclusion in future ABI standards.","Title: Using a High-Performance, Programmable Secure Coprocessor\nYear: 1998\n\nAbstract: Abstract Secure coprocessors enable secure distributed applications by providing safe havens where an application program can execute (and accumulate state), free of observation and interference by an adversary with direct physical access to the device. However, for these coprocessors to be effective, participants in such applications must be able to verify that they are interacting with an authentic program on an authentic, untampered device. Furthermore, secure coprocessors that support general-purposecomputation,and will be manufactured,and distributed as commercial,productsmust provide these core sanctuary and authentication properties while also meeting many additional challenges, including: the applications, operating system, and underlying security management may all come from different, mutually suspicious authorities; configuration and maintenance must occur in a hostile environment, while minimizing disruption of operations; the device must be able to recover from the vulnerabilities that inevitably emerge in complex,software; physical security dictates that the device itself can never be opened,and examined; and ever-evolving cryptographic requirements dictate that hardware,accelerators be supported by reloadable on-card software. This paper summarizes the hardware, software, and cryptographic architecture we developed to address these problems. Furthermore, with our colleagues, we have implemented this solution, into a commercially available product. DRAFT Contents","Title: Electronic prescription for controlled substances: a cybersecurity perspective\nYear: 2013\n\nAbstract: The Electronic Prescription for Controlled Substances (EPCS) is a set of rules published by the Drug Enforcement Administration (DEA) that regulates implementations of electronic prescription systems for controlled substances [1]. EPCS includes requirements two-factor authentication; specifications for electronic prescription applications; and rules governing the signing, transmitting, and receiving of electronic prescriptions [1]. However, this set of regulations overlooks numerous critical aspects of computer security. This paper highlights some key areas in the electronic prescription process outlined by the EPCS regulation that are susceptible to adversarial attacks and provides recommendations for additions to EPCS regulations that would provide greater security for the use of electronic prescriptions.","Title: Interoperable Pki Data Distribution In Computational Grids\nYear: 2009\n\nAbstract: One of the most successful working examples of virtual organizations, computational grids need authentication mechanisms that inter-operate across domain boundaries. Public Key Infrastructures (PKIs) provide sufficient flexibility to allow resource managers to securely grant access to their systems in such distributed environments. However, as PKIs grow and services are added to enhance both security and usability, users and applications must struggle to discover available resources-particularly when the Certification Authority (CA) is alien to the relying party. This article presents how to overcome these limitations of the current grid authentication model by integrating the PKI Resource Query Protocol (PRQP) into the Grid Security Infrastructure (GSI).","Title: High Security With Low Latency In Legacy Scada Systems\nYear: 2010\n\nAbstract: Message authentication with low latency is necessary to ensure secure operations in legacy industrial control networks such as those in the power grid. Previous authentication solutions that examine single messages incur noticeable latency. This paper describes Predictive YASIR, a bump-in-the-wire device that reduces the latency by considering broader patterns of messages. The device predicts the incoming plaintext based on previous observations; compresses, encrypts and authenticates data online; and pre-sends a portion of the ciphertext before receiving the entire plaintext. The performance of Predictive YASIR is evaluated using a simulation involving the Modbus/ASCII protocol. By considering broader message patterns and using predictive analysis, improvements in latency of 15.48 +/- 0.35% are obtained.","Title: PPAA: Peer-to-Peer Anonymous Authentication\nYear: 2008\n\nAbstract: In the pursuit of authentication schemes that balance user privacy and accountability, numerous anonymous credential systems\n have been constructed. However, existing systems assume a client-server architecture in which only the clients, but not the\n servers, care about their privacy. In peer-to-peer (P2P) systems where both clients and servers are peer users with privacy\n concerns, no existing system correctly strikes that balance between privacy and accountability.\n \n In this paper, we provide this missing piece: a credential system in which peers are pseudonymous to one another (that is, two who interact more than once can recognize each other via pseudonyms) but are otherwise anonymous\n and unlinkable across different peers. Such a credential system finds applications in, e.g., Vehicular Ad-hoc Networks (VANets)\n and P2P networks.\n \n \n \n We formalize the security requirements of our proposed credential system, provide a construction for it, and prove the security\n of our construction. Our solution is efficient: its complexities are independent of the number of users in the system.","Title: Private Information Storage With Logarithmic-Space Secure Hardware\nYear: 2004\n\nAbstract: In Private Information Retrieval (PIR), a user obtains one of N records from a server, without the server learning what record was requested.Recent research in \"practical PIR\" has limited the players to the user and server and limited the user's work to negotiating a session key (eg. as in SSL)but then added a secure coprocessor to the server and required the secure coprocessor to encrypt/permute the dataset (and often gone ahead and built real systems).Practical PIR (PPIR) thus consists of trying to solve a privacy problem for a large dataset using the small internal space of the coprocessor. This task is very similar to the one undertaken by the older Oblivious RAMs work, and indeed the latest PPIR work uses techniques developed for Oblivious RAMs. Previous PPIR work had two limitations: the internal space required was still O(N1g N) bits, and records could only be read privately, not written.In this paper, we present a design and experimental results that overcome these limitations. We reduce the internal memory to O(1g N) by basing the pseudorandom permutation on a Luby-Rackoff style block cipher, and by redesigning the oblivious shuffle to reduce space requirements and avoid unnecessary work. This redesign yields both a time and a space savings. These changes expand the system's applicability to larger datasets and domains such as private file storage.These results have been implemented for the IBM 4758 secure coprocessor platform, and are available for download.","Title: Evaluation of efficient security for BGP route announcements using parallel simulation\nYear: 2004\n\nAbstract: The Border Gateway Protocol (BGP) determines how Internet traffic is routed throughout the entire world; malicious behavior by one or more BGP speakers could create serious security issues. Since the protocol depends on a speaker honestly reporting path information sent by previous speakers and involves a large number of independent speakers, the Secure BGP (S-BGP) approach uses public-key cryptography to ensure that a malicious speaker cannot fabricate this information. However, such public-key cryptography is expensive: S-BGP requires a digital signature operation on each announcement sent to each peer, and a linear (in the length of the path) number of verifications on each receipt. We use simulation of AS models derived from the Internet to evaluate the impact that the processing costs of cryptography have on BGP convergence time. As the size of these models grows, inherent memory requirements grow beyond what is normally available in serial computers, motivating us to use distributed memory cluster computers, just to hold the model state. We find that under heavy load the convergence time using ordinary S-BGP is significantly larger than BGP. We examine the impact of highly aggressive caching and pre-computation optimizations for S-BGP, and find that convergence time is much closer to BGP. However, these optimizations may be unrealistic, and are certainly expensive of memory. We consequently use the structure of BGP processing to design optimizations that reduce cryptographic overhead by amortizing the cost of private-key signatures over many messages. We call this method Signature-Amortization (S-A). We find that S-A provides as good or better convergence times as the highly optimized S-BGP, but without the cost and complications of caching and pre-computation. These experiments––whose memory demands easily exceed 10Gb––are made possible using parallel simulation. They show that it is is possible therefore to minimize the impact route validation has on convergence, by being careful with signatures, rather than consumptive of memory.","Title: Secure cryptographic precomputation with insecure memory\nYear: 2008\n\nAbstract: We propose a solution that provides secure storage for cryptographic precomputation using insecure memory that is susceptible to eavesdropping and tampering. Specifically, we design a small tamper-resistant hardware module, the Queue Security Proxy (QSP), that situates transparently on the data-path between the processor and the insecure memory. Our analysis shows that our design is secure and flexible, and yet efficient and inexpensive. In particular, both the timing overhead and the hardware cost of our solution are independent of the storage size.","Title: Extending PKI Interoperability in Computational Grids\nYear: 2008\n\nAbstract: One of the most successful working examples of virtualor ganizations, computational grids need authentication mechanisms that inter-operate across domain boundaries. Public Key Infrastructures (PKIs) provide sufficient flexibility to allow resource managers to securely grant access to their systems in such distributed environments. However, as PKIs grow and services are added to enhance both security and usability, users and applications must struggle to discover available resources—particularly when the Certification Authority (CA) is alien to the relying party. This paper presents how to overcome these limitations of the current grid authentication model by integrating the PKI Resource Query Protocol (PRQP) into the Grid Security Infrastructure (GSI).","Title: Building a high-performance, programmable secure coprocessor\nYear: 1999\n\nAbstract: Secure coprocessors enable secure distributed applications by providing safe havens where an application program can execute (and accumulate state), free of observation and interference by an adversary with direct physical access to the device. However, for these coprocessors to be effective, participants in such applications must be able to verify that they are interacting with an authentic program on an authentic, untampered device. Furthermore, secure coprocessors that support general-purpose computation and will be manufactured and distributed as commercial products must provide these core sanctuary and authentication properties while also meeting many additional challenges, including: • the applications, operating system, and underlying security management may all come from different, mutually suspicious authorities; • configuration and maintenance must occur in a hostile environment, while minimizing disruption of operations; • the device must be able to recover from the vulnerabilities that inevitably emerge in complex software; • physical security dictates that the device itself can never be opened and examined; and • ever-evolving cryptographic requirements dictate that hardware accelerators be supported by reloadable on-card software. This paper summarizes the hardware, software, and cryptographic architecture we developed to address these problems. Furthermore, with our colleagues, we have implemented this solution, into a commercially available product.","Title: AutoPKI: a PKI resources discovery system\nYear: 2007\n\nAbstract: The central goal of Public Key Infrastructure (PKI) is to enable trust judgments between distributed users. Although certificates play a central role in making such judgments, a PKI's users need more than just knowledge of certificates. Minimally, a relying party must able to locate critical parameters such the certificate repositories and certificate validation servers relevant to the trust path under consideration. Users in other scenarios may require other resources and services. Surprisingly, locating these resources and services remains a largely unsolved problem in real-world X.509 PKI deployment. In this paper, we present the design and prototype of a new and flexible solution for automatic discovery of the services and data repositories are available from a Certificate Service Provider (CSP). This contribution will take real-world PKI one step closer to achieving its goal.","Title: XUTools: UNIX commands for processing next-generation structured text\nYear: 2012\n\nAbstract: Traditional Unix tools operate on sequences of characters, bytes, fields, lines, and files. However, modern practitioners often want to manipulate files in terms of a variety of language-specific constructs--C functions, Cisco IOS interface blocks, and XML elements, to name a few. These language-specific structures quite often lie beyond the regular languages upon which Unix text-processing tools can practically compute. In this paper, we propose eXtended Unix text-processing tools (xutools) and present implementations that enable practitioners to extract (xugrep), count (xuwc), and compare (xudiff) texts in terms of language-specific structures. We motivate, design, and evaluate our tools around real-world use cases from network and system administrators, security consultants, and software engineers from a variety of domains including the power grid, healthcare, and education.","Title: Why Do Street-Smart People Do Stupid Things Online?\nYear: 2008\n\nAbstract: The current epidemic of poor trust decisions by users online is largely due to flaws in GUIs that train the users away from using real-world security intuitions. The authors propose a principle for GUI designers that will help them avoid such design mistakes.","Title: BLAC: Revoking Repeatedly Misbehaving Anonymous Users without Relying on TTPs\nYear: 2010\n\nAbstract: Several credential systems have been proposed in which users can authenticate to service providers anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a Trusted Third Party (TTP). The ability of the TTP to revoke a user’s privacy at any time, however, is too strong a punishment for misbehavior. To limit the scope of deanonymization, some systems have been proposed in which users can be deanonymized only if they authenticate “too many times,” such as “double spending” with electronic cash. While useful in some applications, such techniques cannot be generalized to more subjective definitions of misbehavior, for example, using such schemes it is not possible to block anonymous users who “deface too many Web pages” on a Web site. We present BLAC, the first anonymous credential system in which service providers can revoke the credentials of misbehaving users without relying on a TTP . Since revoked users remain anonymous, misbehaviors can be judged subjectively without users fearing arbitrary deanonymization by a TTP . Additionally, our construction supports a d-strikes-out revocation policy, whereby users who have been subjectively judged to have repeatedly misbehaved at least d times are revoked from the system. Thus, for the first time, it is indeed possible to block anonymous users who have “defaced too many Web pages” using our scheme.","Title: Design and Prototype of a Coercion-Resistant, Verifiable Electronic Voting System\nYear: 2004\n\nAbstract: In elections, it is important that voters be able to verify that the tally reflects the sum of the votes that were actually cast, as they were intended to be cast. It is also important that voters not be subject to coercion from adversaries. Currently most proposed voting systems fall short: they either do not provide both properties, or require the voter to be a computer. In this paper, we present a new voting system that uses voter knowledge to allow voter verification by using a receipt that is uninformative for a coercer without access to the voting machine or the contents of the cast ballots. Our system does not assume any trust in the voting machine, but requires a few other assumptions which we believe to be reasonable in the real-world situation. A basic prototype of this system is available on our website. I. INTRODUCTION The US presidential elections of 2000 made the general public aware of the problems of producing a voting system that could be trusted by the voters to submit their votes correctly. Despite the public review and control of the US electoral system, many US citizens felt that the system had failed them. Although the problems did not originate in the 2000 election, the situation where a very small number of votes was sufficient to flip the final tally raised the public's awareness of the inadequacy of the system. The problem of producing a fair voting system has been well-known in countries and situations where adversaries have a very high degree of control. In totalitarian societies (or other situations with almost complete adversarial control), it may be futile to attempt to solve this problem. Such societies provide no guarantee that the adversary will comply with the solution, no guarantee that the observers and complainants will be able to speak up, and no guarantee that the situation will be corrected even if there is a valid complaint. However, in a free democratic society in the 21st century, the electoral system is subject to public review and control. Its failures do not have to be possible. If an electronic voting system is to be applied in secret- ballot elections, it has to be receipt-free, i.e. not allow a voter to carry away any evidence of who he voted for, since such evidence would permit vote buying and coercion. Receipt- freeness is hard to combine with voter verifiability: if a voter is able to verify that his vote was counted as he cast it, what could prevent him from proving how he voted to a third party? Cryptography can help address this seeming incompatibility between receipt-freeness and voter verifiability, if the voter has an encrypted copy of his vote and can verify that his encrypted vote made it to the final tally. However, that requires the voter to be able to verify that the encryption of his vote is correct. Chaum's layered receipts (5) (discussed below) solve this problem partially: they allow verification, but only with probability 50%. In this paper, we examine these properties and survey the principal current approaches to electronic voting systems. We then present a new design that improves on the previous work, by being (arguably) the first one that achieves both voter verifiability and coercion resistance, while not assuming the voter is a computer, not relying on correct behavior by the voting machine, and detecting close to 100% of misbehaviour. Section II briefly discusses the requirements for a secure election system. Section III presents a brief overview of methods used in receipt-free election schemes. Section IV discusses the most recently implemented election schemes. Section V presents our election scheme. Section VI discusses the practical applicability of our scheme. Section VII describes our prototype. Section VIII offers some concluding remarks.","Title: Trusting trusted hardware: towards a formal model for programmable secure coprocessors\nYear: 1998\n\nAbstract: Secure coprocessors provide a foundation for many exciting electronic commerce applications, as previous work [20, 21] has demonstrated. As our recent work [6, 13, 14] has explored, building a high-end secure coprocessor that can be easily programmed and deployed by a wide range of third parties can be an important step toward realizing this promise. But this step requires trusting trusted hardware-and achieving this trust can be difficult in the face of a problem and solution space that can be surprisingly complex and subtle. Formal methods provide one means to express, verify, and analyze such solutions (and would be required for such a solution to be certified at FIPS 140-1 Level 4). This paper discusses our current efforts to apply these principles to the architecture of our secure coprocessor. We present formal statements of the security goals our architecture needs to provide; we argue for correctness by enumerating the architectural properties from which these goals can be proven; we argue for conciseness by showing how eliminating properties causes the goals to fail; but we discuss how simpler versions of the architecture can satisfy weaker security goals. We view this work as the beginning of developing formal models to address the trust challenges arising from using trusted hardware for electronic commerce.","Title: PorKI: portable PKI credentials via proxy certificates\nYear: 2010\n\nAbstract: Authenticating human users using public key cryptography provides a number of useful security properties, such as being able to authenticate to remote party without giving away a secret. However, in many scenarios, users need to authenticate from a number of client machines, of varying degrees of trustworthiness. In previous work, we proposed an approach to solving this problem by giving users portable devices which wirelessly issue temporary, limited-use proxy certificates to the clients. In this paper, we describe our complete prototype, enabling the use of proxy credentials issued from a mobile device to securely authenticate users to remote servers via a shared (or otherwise not trusted) device. In particular, our PorKI implementation combines out-of-band authentication (via 2D barcode images), standard Proxy Certificates, and platform attestation to provide usable and secure temporary credentials for web-based applications.","Title: TwoKind authentication: protecting private information in untrustworthy environments\nYear: 2008\n\nAbstract: Users often log in to Internet sites from insecure computers and more recently have started divulging their email passwords to social-networking sites, thereby putting their private communications at risk. We propose and evaluate TwoKind Authentication, a simple and effective technique for limiting access to private information in untrustworthy environments. In its simplest form, TwoKind offers two modes of authentication by providing a low and a high authenticator. By using a low authenticator, users can signal to the server that they are in an untrusted environment, following which the server restricts the user's actions. We seek to evaluate the effectiveness of multiple authenticators in promoting safer behavior in users. We demonstrate the effectiveness of this approach through a user experiment - we find that users make a distinction between the two authenticators and generally behave in a security-conscious way, protecting their high authenticator the ma jority of the time. Our study suggests that TwoKind will be beneficial to several Internet applications, particularly if the privileges associated with the low authenticator can be customized to a user's security preferences.","Title: Traps, events, emulation, and enforcement: managing the yin and yang of virtualization-based security\nYear: 2008\n\nAbstract: We question current trends that attempt to leverage virtualization techniques to achieve security goals. We suggest that the security role of a virtual machine centers on being a policy interpreter rather than a resource provider. These two roles (security reference monitor and resource emulator) are currently conflated within the context of virtual machines and VMMs. We believe that this ``double-duty'' leads to both a significant performance impact as well as a bloated virtualization layer. Increased complexity reduces confidence that the code is elementary enough to verify or trust from a security perspective. Ironically, as more security-related functionality is shoved into a VM platform, the system becomes less trustworthy as it becomes increasingly trusted. We argue that a principle reason for such an unfortunate situation is the lack of efficient hardware trapping mechanisms. We propose an architecture to help ameliorate this problem by transferring the security enforcement and program analysis roles from the virtualization component to a policy-directed FPGA.","Title: \"Weird machines\" in ELF: a spotlight on the underappreciated metadata\nYear: 2013\n\nAbstract: Although software exploitation historically started as an exercise in coaxing the target's execution into attacker-supplied binary shellcode, it soon became a practical study in pushing the limits of unexpected computation that could be caused by crafted data not containing any native code. We show how the ABI metadata that drives the creation of a process' runtime can also drive arbitrary computation. We introduce our design and implementation of Cobbler, a proof-of-concept toolkit capable of compiling a Turing-complete language into well-formed ELF executable metadata that get \"executed\" by the runtime loader (RTLD). Our proof-of-concept toolkit highlights how important it is that defenders expand their focus beyond the code and data sections of untrusted binaries, both in static analysis and in the dynamic analysis of the early runtime setup stages as well as any time the RTLD is invoked.","Title: Using active intrusion detection to recover network trust\nYear: 2011\n\nAbstract: Most existing intrusion detection systems take a passive approach to observing attacks or noticing exploits. We suggest that active intrusion detection (AID) techniques provide value, particularly in scenarios where an administrator attempts to recover a network infrastructure from a compromise. In such cases, an attacker may have corrupted fundamental services (e.g., ARP, DHCP, DNS, NTP), and existing IDS or auditing tools may lack the precision or pervasive deployment to observe symptoms of this corruption. We prototype a specific instance of the active intrusion detection approach: how we can use an AID mechanism based on packet injection to help detect rogue services.","Title: Combating spam and denial-of-service attacks with trusted puzzle solvers\nYear: 2008\n\nAbstract: Cryptographic puzzles can be used to mitigate spam and denial-of-service (DoS) attacks, as well as to implement timed-release cryptography. However, existing crypto puzzles are impractical because: (1) solving them wastes computing resources and/or human time, (2) the time it takes to solve them can vary dramatically across computing platforms, and/or (3) applications become non-interoperable due to competition for resources when solving them. We propose the use of Trusted Computing in constructing crypto puzzles. Our puzzle constructions have none of the drawbacks above and only require each client machine to be equipped with a small tamper-resistant Trusted Puzzle Solver (TPS), which may be realized using the prevalent Trusted Platform Module (TPM) with minimal modifications.","Title: Improved learning of AC0 functions\nYear: 1991\n\nAbstract: Two extensions of the Linial, Mansour, Nisan 0 learning algorithm are presented. The LMN method works when input examples are drawn uniformly. The new algorithms improve on theirs by performing well when given inputs drawn from unknown, mutually independent distribu- tions. A variant of the one of the algorithms is conjectured to work in an even broader setting.","Title: Cryptographic scalability challenges in the smart grid (extended abstract)\nYear: 2012\n\nAbstract: In the envisioned smart grid, massive numbers of computational devices will need to authenticate to each other. For scalability, this technology will probably rest on public-key infrastructure (PKI). However, deploying PKI on an entity population this large -- and doing the kinds of things we envision the smart grid doing -- itself raises many scalability challenges the community will need to address. We survey some.","Title: Katana: Towards Patching as a Runtime Part of the Compiler-Linker-Loader Toolchain\nYear: 2010\n\nAbstract: The mechanics of hot patching the process of upgrading a program while it executes remain understudied, even though it offers capabilities that act as practical benefits for both consumer and mission-critical systems. A reliable hot patching procedure would serve particularly well by reducing the downtime necessary for critical functionality or security upgrades. However, hot patching also carries the risk-real or perceived-of leaving the system in an inconsistent state, which leads many owners to forgo its benefits as too risky; for systems where availability is critical, this decision may result in leaving systems un-patched and vulnerable. In this paper, the authors present a novel method for hot patching ELF binaries that supports synchronized global data and code updates, and reasoning about the results of applying the hot patch. In this regard, the Patch Object format was developed to encode patches as a special type of ELF re-locatable object file. The authors then built a tool, Katana, which automatically creates these patch objects as a by-product of the standard source build process. Katana also allows an end-user to apply the Patch Objects to a running process.","Title: Pretending that Systems Are Secure\nYear: 2005\n\nAbstract: We look at the societal aspects in this installment: the formal education process through which we train students, young and old, to be effective cyber-citizens; and the media coverage and editorializing process through which we express (or perhaps imprint) ethical judgment.","Title: Nymble: Blocking Misbehaving Users in Anonymizing Networks\nYear: 2011\n\nAbstract: Anonymizing networks such as Tor allow users to access Internet services privately by using a series of routers to hide the client's IP address from the server. The success of such networks, however, has been limited by users employing this anonymity for abusive purposes such as defacing popular Web sites. Web site administrators routinely rely on IP-address blocking for disabling access to misbehaving users, but blocking IP addresses is not practical if the abuser routes through an anonymizing network. As a result, administrators block all known exit nodes of anonymizing networks, denying anonymous access to misbehaving and behaving users alike. To address this problem, we present Nymble, a system in which servers can “blacklist” misbehaving users, thereby blocking users without compromising their anonymity. Our system is thus agnostic to different servers' definitions of misbehavior—servers can blacklist users for whatever reason, and the privacy of blacklisted users is maintained.","Title: The page-fault weird machine: lessons in instruction-less computation\nYear: 2013\n\nAbstract: Trust Analysis, i.e. determining that a system will not execute some class of computations, typically assumes that all computation is captured by an instruction trace. We show that powerful computation on ×86 processors is possible without executing any CPU instructions. We demonstrate a Turing-complete execution environment driven solely by the IA32 architecture's interrupt handling and memory translation tables, in which the processor is trapped in a series of page faults and double faults, without ever successfully dispatching any instructions. The \"hard-wired\" logic of handling these faults is used to perform arithmetic and logic primitives, as well as memory reads and writes. This mechanism can also perform branches and loops if the memory is set up and mapped just right. We discuss the lessons of this execution model for future trustworthy architectures.","Title: Computational techniques for increasing PKI policy comprehension by human analysts\nYear: 2010\n\nAbstract: Natural-language policies found in X.509 PKI describe an organization's stated policy as a set of requirements for trust. The widespread use of X.509 underscores the importance of understanding these requirements. Although many review processes are defined in terms of the semantic structure of these policies, human analysts are confined to working with page-oriented PDF texts. Our research accelerates PKI operations by enabling machines to translate between policy page numbers and policy reference structure. Adapting technologies supporting the analysis of Classical texts, we introduce two new tools. Our Vertical Variance Reporter helps analysts efficiently compare the reference structure of two policies. Our Citation-Aware HTML enables machines to process human-readable displays of policies in terms of this reference structure. We evaluate these contributions in terms of real-world feedback and observations from organizations that audit or accredit policies.","Title: Building the IBM 4758 Secure Coprocessor\nYear: 2001\n\nAbstract: The authors sought to build a secure coprocessor驴defined as a tamper-responding device derived from the Abyss, Citadel, and 4755 work驴that would provide a single multipurpose platform third parties could use to develop and deploy secure coprocessor applications, with minimal IBM participation. The project had several goals: ensure that the device could be identified externally, design the device and its soft-ware to be securely configurable and updatable in the field, construct the software architecture to accommodate layers of code from different parties, avoid letting the compromise of one device breach any other's security, and validate all these assertions through an external party.Providing an environment in which applications could run securely forced the designers to focus not only on security mechanisms and their implementation and management, but also on the security policies they must support. Clearly, the hardware on which applications run must be secure, as must the operating system and run-time environment in between, while offering a reasonable API for applications developers. To fix problems in the field and enable fast and inexpensive reaction to changing customer needs, the designers implemented part of the code as firmware rather than as read-only memory.The 4758 project achieved most of its design goals. Currently, the authors are exploring other embedded processors, the addition of a network communication channel, and other form factors, including those appropriate for laptops.","Title: Nymble: anonymous IP-address blocking\nYear: 2007\n\nAbstract: Anonymizing networks such as Tor allow users to access Internet services privately using a series of routers to hide the client's IP address from the server. Tor's success, however, has been limited by users employing this anonymity for abusive purposes, such as defacing Wikipedia. Website administrators rely on IP-address blocking for disabling access to misbehaving users, but this is not practical if the abuser routes through Tor. As a result, administrators block all Tor exit nodes, denying anonymous access to honest and dishonest users alike. To address this problem, we present a system in which (1) honest users remain anonymous and their requests unlinkable; (2) a server can complain about a particular anonymous user and gain the ability to blacklist the user for future connections; (3) this blacklisted user's accesses before the complaint remain anonymous; and (4) users are aware of their blacklist status before accessing a service. As a result of these properties, our system is agnostic to different servers' definitions of misbehavior.","Title: Open-Source Applications of TCPA Hardware\nYear: 2004\n\nAbstract: How can Alice trust computation occurring at Bob's computer? Since it exists and is becoming ubiquitous, the current-generation TCPA/TCG hardware might enable a solution. When we started investigating this technology, the specification of the TCG software stack was not publicly available, and an implementation is still not; so, we designed and built an open-source platform based on Linux and commercially available TCPA/TCG hardware which would allow us to address the problem of trusting computation. Within the limits of TCPA/TCG hardware security, our solution balances what Alice needs to do to make trust judgments against what Bob needs to do to keep his system running. Furthermore, we describe how we use our platform to harden three sample open-source applications: Apache SSL Web servers, OpenCA certification authorities, and (with SELinux) compartmented attestation to balance privacy with DRM. To our knowledge, our project remains the only open-source TCPA/TCG platform in existence, and is also enabling trusted computing applications developed by our user community (enforcer.sourceforge.net reports over 1100 sourcecode downloads so far).","Title: The effects of introspection on creating privacy policy\nYear: 2009\n\nAbstract: Prior work in psychology shows that introspection inhibits intuition: asking human users to analyze judgements they make can cause them to be quantitatively worse at making those judgments. In this paper, we explore whether this seemingly contradictory phenomenon also occurs when humans craft privacy policies for a Facebook-like social network. Our study presents empirical evidence that suggests the act of introspecting upon one's personal security policy actually makes one worse at making policy decisions; if one aims to reduce privacy spills, the data indicate that educating users before letting them set their privacy policies may actually increase the exposure of private information.","Title: Digital signatures and electronic documents: a cautionary tale\nYear: 2002\n\nAbstract: Often, the main motivation for using PKI in business environments is to streamline workflow, by enabling humans to digitally sign electronic documents, instead of manually signing paper ones. However, this application fails if adversaries can construct electronic documents whose viewed contents can change in useful ways, without invalidating the digital signature. In this paper, we examine the space of such attacks, and describe how many popular electronic document formats and PKI packages permit them.","Title: Aggregated path authentication for efficient BGP security\nYear: 2005\n\nAbstract: The Border Gateway Protocol (BGP) controls inter-domain routing in the Internet. BGP is vulnerable to many attacks, since routers rely on hearsay information from neighbors. Secure BGP (S-BGP) uses DSA to provide route authentication and mitigate many of these risks. However, many performance and deployment issues prevent S-BGP's real-world deployment. Previous work has explored improving S-BGP processing latencies, but space problems, such as increased message size and memory cost, remain the major obstacles. In this paper, we design aggregated path authentication schemes by combining two efficient cryptographic techniques---signature amortization and aggregate signatures. We propose six constructions for aggregated path authentication that substantially improve efficiency of S-BGP's path authentication on both speed and space criteria. Our performance evaluation shows that the new schemes achieve such an efficiency that they may overcome the space obstacles and provide a real-world practical solution for BGP security.","Title: What's Wrong with Access Control in the Real World?\nYear: 2010\n\nAbstract: This article enumerates some simplifying assumptions the security community has made in its effort to gain traction with the access control problem. For many environments, a dramatic and painful mismatch seems to exist between these simplifying assumptions and reality. The authors argue that effective security in these environments might therefore require rethinking these assumptions.","Title: Completely Asynchronous Optimistic Recovery with Minimal Rollbacks\nYear: 1995\n\nAbstract: Consider the problem of transparently recovering an asynchronous distributed computation when one or more processes fail. Basing rollback recovery on optimistic message logging and replay is desirable for several reasons, including not requiring synchronization between processes during failure-free operation. However, previous optimistic rollback recovery protocols either have required synchronization during recovery, or have permitted a failure at one process to potentially trigger an exponential number of process rollbacks. In this paper, we present an optimistic rollback recovery protocol that provides completely asynchronous recovery, while also reducing the number of times a process must roll back in response to a failure to at most one. This protocol is based on comparing timestamp vectors across multiple levels of partial order time.","Title: Room at the Bottom: Authenticated Encryption on Slow Legacy Networks\nYear: 2011\n\nAbstract: The author proposes a streamwise model for online encryption for slow legacy networks.","Title: Healthcare information technology's relativity problems: a typology of how patients' physical reality, clinicians' mental models, and healthcare information technology differ.\nYear: 2014\n\nAbstract: Objective To model inconsistencies or distortions among three realities: patients' physical reality; clinicians' mental models of patients' conditions, laboratories, etc; representation of that reality in electronic health records (EHR). To serve as a potential tool for quality improvement of EHRs. Methods Using observations, literature, information technology (IT) logs, vendor and US Food and Drug Administration reports, we constructed scenarios/models of how patients' realities, clinicians' mental models, and EHRs can misalign to produce distortions in comprehension and treatment. We then categorized them according to an emergent typology derived from the cases themselves and refined the categories based on insights gained from the literature of interactive sociotechnical systems analysis, decision support science, and human computer interaction. Typical of grounded theory methods, the categories underwent repeated modifications. Results We constructed 45 scenarios of misalignment between patients' physical realities, clinicians' mental models, and EHRs. We then identified five general types of misrepresentation in these cases: IT data too narrowly focused; IT data too broadly focused; EHRs miss critical reality; data multiplicities-perhaps contradictory or confusing; distortions from data reflected back and forth across users, sensors, and others. The 45 scenarios are presented, organized by the five types. Conclusions With humans, there is a physical reality and actors' mental models of that reality. In healthcare, there is another player: the EHR/healthcare IT, which implicitly and explicitly reflects many mental models, facets of reality, and measures thereof that vary in reliability and consistency. EHRs are both microcosms and shapers of medical care. Our typology and scenarios are intended to be useful to healthcare IT designers and implementers in improving EHR systems and reducing the unintended negative consequences of their use.","Title: Blacklistable anonymous credentials: blocking misbehaving users without ttps\nYear: 2007\n\nAbstract: Several credential systems have been proposed in which users can authenticate to services anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a trusted third party (TTP). The ability of the TTP to revoke a user's privacy at any time, however, is too strong a punishment for misbehavior. To limit the scope of deanonymization, systems such as \"e-cash\" have been proposed in which users are deanonymized under only certain types of well-defined misbehavior such as \"double spending.\" While useful in some applications, it is not possible to generalize such techniques to more subjective definitions of misbehavior. We present the first anonymous credential system in which services can \"blacklist\" misbehaving users without contacting a TTP. Since blacklisted users remain anonymous, misbehaviors can be judged subjectively without users fearing arbitrary deanonymization by a TTP.","Title: Virtualization and Security: Back to the Future\nYear: 2008\n\nAbstract: The guest editors of the special issue on virtualization introduce the topic space.","Title: Using hierarchal change mining to manage network security policy evolution\nYear: 2011\n\nAbstract: Managing the security of complex cloud and networked computing environments requires crafting security policy--ranging from natural-language text to highly-structured configuration rules, sometimes multi-layered--specifying correct system behavior in an adversarial environment. Since environments change and evolve, managing security requires managing evolution of policies, which adds another layer, the change log. However, evolution increases complexity, and the more complex a policy, the harder it is to manage and update, and the more prone it is to be incorrect. This paper proposes hierarchical change mining, drawing upon the tools of software engineering and data mining, to help practitioners introduce fewer errors when they update policy. We discuss our approach and initial findings based on two longitudinal real-world datasets: low-level router configurations from Dartmouth College and high-level Public Key Infrastructure (PKI) certificate policies from the International Grid Trust Federation (IGTF).","Title: Securing Information Technology in Healthcare.\nYear: 2013\n\nAbstract: Dartmouth College's Institute for Security, Technology, and Society conducted three workshops on securing information technology in healthcare, attended by a diverse range of experts in the field. This article summarizes the three workshops.","Title: Shemp: secure hardware enhanced myproxy\nYear: 2005\n\nAbstract: In 1976, Whitfield Diffie and Martin Hellman demonstrated how public key cryptography could enable secure information exchange between parties that do not share secrets. In order for public key cryptography to work in modern distributed environments, we need an infrastructure for finding and trusting other parties' public keys, i.e., a Public Key Infrastructure (PKI). While PKI applications differ in how they use keys, all applications share one assumption: users have keypairs. This thesis begins by examining the security aspects of some of the standard keystores and their interaction with the Operating System. We establish that desktop keystores are not safe places to store private keys, and our experiments demonstrate the permeability of such keystores. Additionally, desktop keystores are immobile, difficult to use, and make it hard or impossible for relying parties to make reasonable trust judgments. We show that these problems stem from the fact that the Trusted Computing Base (TCB) of modern desktops is too large and ill-defined, which makes standard desktops suboptimal PKI clients. Since we would like to use desktops as PKI clients and cannot realistically expect to redesign the entire desktop, this thesis presents a system that works within the confines of modern desktops to shrink the TCB needed for PKI applications. Our system is called Secure Hardware Enhanced MyProxy (SHEMP), and combines a number of techniques and technologies to shrink the TCB in space and allow the TCB's size to vary over time. In addition, the SHEMP system addresses the problems of immobility and usability, and allows relying parties to make reasonable trust judgments. Using analysis, experiments, and formal methods, we conclude that SHEMP makes standard desktops suitable for use as PKI clients. The contributions of this thesis include the discovery of techniques used to identify weaknesses in modern desktops; a prototype, analysis, and correctness proof of a system which makes desktops usable as PKI clients (SHEMP); a novel approach for reasoning about TCBs; and a formal framework for proving properties of PKI systems such as SHEMP.","Title: The diversity of TPMs and its effects on development: a case study of integrating the TPM into OpenSolaris\nYear: 2010\n\nAbstract: Broad adoption of secure programming primitives such as the TPM can be hurt by programmer confusion regarding the nature and representation of failures when using a primitive. Conversely, a clear understanding of the primitive's failure modes is essential for both debugging and reducing the attack surface in the mechanisms built on it. In particular, differences in error processing and reporting logic significantly detract from such understanding. We present a case study of diversity in TPM behaviors and its effects on a TSS implementation, which emerged from the Sun/Dartmouth TCG/OpenSolaris project, one of the goals of which was instrumenting TPM support on Solaris. At the start of the project, both parties believed the instrumentation to be well-defined and, although time-consuming, relatively straightforward. In the course of the project we had to reexamine our assumptions concerning the state of the hardware and the software involved and the view of the system as presented to someone unfamiliar with its internals. We describe some failure modes we encountered and suggest directions for remediation.","Title: Using caching for browsing anonymity\nYear: 2003\n\nAbstract: Privacy-providing tools, including tools that provide anonymity, are gaining popularity in the modern world. Among the goals of their users is avoiding tracking and profiling. While some businesses are unhappy with the growth of privacy-enhancing technologies, others can use lack of information about their users to avoid unnecessary liability and even possible harassment by parties with contrary business interests, and to gain a competitive market edge.Currently, users interested in anonymous browsing have the choice only between single-hop proxies and the few more complex systems that are available. These still leave the user vulnerable to long-term intersection attacks.In this paper, we propose a caching proxy system for allowing users to retrieve data from the World-Wide Web in a way that would provide recipient unobservability by a third party and sender unobservability by the recipient and thus dispose with intersection attacks, and report on the prototype we built using Google.","Title: TOCTOU, Traps, and Trusted Computing\nYear: 2008\n\nAbstract: The security of the standard TCG architecture depends on whether the values in the platform configuration reg- isters match the actual platform configuration. How- ever, the design of this architecture admits potential for time-of-check time-of-use vulnerabilities: a PCR reflects the value of software and data when it was measured, not when the TPM uses a credential or signs an attes- tation based on that measurement. In this paper, we demonstrate how an attacker with sucient privileges can compromise the integrity of a TPM-protected sys- tem by modifying critical loaded code and static data af- ter measurement has taken place. To solve this problem, we explore using the MMU and the TPM in concert to provide a memory event trapping framework, in which trap handlers perform TPM operations to enforce a se- curity policy. Our framework proposal includes modify- ing the MMU to support selective memory immutability and generate higher granularity memory access traps. To substantiate our ideas, we designed and implemented a software prototype system employing the monitoring capabilities of the Xen virtual machine monitor. We evaluate both the security eectiveness and the perfor- mance overhead of this prototype.","Title: Trusted virtual containers on demand\nYear: 2010\n\nAbstract: TPM-based trusted computing aspires to use hardware and cryptography to provide a remote relying party with assurances about the trustworthiness of a computing environment. However, standard approaches to trusted computing are hampered in the areas of scalability, expressiveness, and flexibility. This paper reports on our research project to address these limitations by using TPMs inside OpenSolaris: our kernel creates lightweight containers on demand, and uses DTrace and other tools to extend attestation to more nuanced runtime properties. We illustrate this work with prototype application scenarios from cyber infrastructure operating the U.S. power grid.","Title: Yasir: A Low-Latency, High-Integrity Security Retrofit For Legacy Scada Systems\nYear: 2008\n\nAbstract: We construct a bump-in-the-wire (BITW) solution that retrofits security into time-critical communications over bandwidth-limited serial links between devices in legacy Supervisory Control And Data Acquisition (SCADA) systems, on which the proper operations of critical infrastructures such as the electric power grid rely. Previous BITW solutions do not provide the necessary security within timing constraints; the previous solution that does is not BITW. At a hardware cost comparable to existing solutions, our BITW solution provides sufficient security, and yet incurs minimal end-to-end communication latency.","Title: A computational framework for certificate policy operations\nYear: 2009\n\nAbstract: The trustworthiness of any Public Key Infrastructure (PKI) rests upon the expectations for trust, and the degree to which those expectations are met. Policies, whether implicit as in PGP and SDSI/SPKI or explicitly required as in X.509, document expectations for trust in a PKI. The widespread use of X.509 in the context of global e-Science infrastructures, financial institutions, and the U.S. Federal government demands efficient, transparent, and reproducible policy decisions. Since current manual processes fall short of these goals, we designed, built, and tested computational tools to process the citation schemes of X.509 certificate policies defined in RFC 2527 and RFC 3647. Our PKI Policy Repository, PolicyBuilder, and PolicyReporter improve the consistency of certificate policy operations as actually practiced in compliance audits, grid accreditation, and policy mapping for bridging PKIs. Anecdotal and experimental evaluation of our tools on real-world tasks establishes their actual utility and suggests how machine-actionable policy might empower individuals to make informed trust decisions in the future.","Title: Finding the PKI needles in the Internet haystack\nYear: 2010\n\nAbstract: Public key cryptography can uniquely enable trust within distributed settings. Employing it usually requires deploying a set of tools and services collectively known as a Public Key Infrastructure (PKI). PKIs have become a central asset for many organizations, due to distributed IT and users. Even though the usage of PKIs in closed and controlled environments is quite common, interoperability and usability problems arise when shifting to a broader, open environment. To make an effective trust judgment about a public key certificate, a PKI user needs more than just knowledge of that certificate: she also needs to be able to locate critical parameters such as the certificate repositories and certificate validation servers relevant to that certificate - and all the others the trust path she builds for it. Surprisingly, locating these resources and services remains a largely unsolved problem in real-world X.509 PKI deployment. This issue impacts especially on the usability of this technology and the interoperability of PKIs in open environments such as the Internet. In this paper, we present the design and prototype of a new and flexible solution for automatic discovery of the services and data repositories made available by a Certificate Service Provider (CSP). This contribution will take real-world PKI one step closer to enhancing usability of digital certificates and interoperability between PKIs.","Title: TwoKind authentication: usable authenticators for untrustworthy environments\nYear: 2007\n\nAbstract: The ease with which a malicious third party can obtain a user's password when he or she logs into Internet sites (such as bank or email accounts) from an insecure computer creates a substantial security risk to private information and transactions. For example, a malicious administrator at a cybercafe, or a malicious user with sufficient access to install key loggers at a kiosk, can obtain users' passwords easily. Even when users do not trust the machines they are using, many of them are faced with the prospect of accessing their accounts with a single level of privilege. To address this problem, we propose a system based on two modes of authentication--default and restricted. Users can signal to the server whether they are in an untrusted environment so that the server can log them in under restricted privileges that allow them to perform basic actions that cause no serious damage if the session or their password is compromised.","Title: Grand Challenges in Information Security: Process and Output\nYear: 2004\n\nAbstract: Even casual observers can see that our society's computing infrastructure has significant security problems. Technical sources such as CERT, BugTraq, and the Risks Digest - not to mention the popular media - regularly catalog critical vulnerabilities in deployed software. Unless we figure out how to build trustworthy systems in the real world, we're in trouble. Recognizing that fact, the Computing Research Association (CRA, www.cra.org), with support from the US National Science Foundation, recently drafted its Grand Research Challenges in security and assurance, intent on galvanizing the field by focusing attention and stimulating progress on these problems.","Title: PEREA: towards practical TTP-free revocation in anonymous authentication\nYear: 2008\n\nAbstract: Several anonymous authentication schemes allow servers to revoke a misbehaving user's ability to make future accesses. Traditionally, these schemes have relied on powerful TTPs capable of deanonymizing (or linking) users' connections. Recent schemes such as Blacklistable Anonymous Credentials (BLAC) and Enhanced Privacy ID (EPID) support \"privacy-enhanced revocation\" -- servers can revoke misbehaving users without a TTP's involvement, and without learning the revoked users' identities. In BLAC and EPID, however, the computation required for authentication at the server is linear in the size (L) of the revocation list. We propose PEREA, a new anonymous authentication scheme for which this bottleneck computation is independent of the size of the revocation list. Instead, the time complexity of authentication is linear in the size (K L) of a revocation window, the number of subsequent authentications before which a user's misbehavior must be recognized if the user is to be revoked. We prove the security of our construction, and have developed a prototype implementation of PEREA to validate its efficiency experimentally.","Title: Information Risk in Financial Institutions: Field Study and Research Roadmap\nYear: 2007\n\nAbstract: Large financial firms with thousands of employees face many challenges ensuring workers have access to the right information, yet controlling access to unneeded data. We examine the problems of role lifecycle management and entitlement review processes in the context of large financial institutions. We describe observations from field study research in both retail and investment banks. We examine technologies to enable role and entitlement management and present a roadmap for future research.","Title: Never Mind Pearl Harbor--What about a Cyber Love Canal?\nYear: 2015\n\nAbstract: Focusing on malicious attacks on the current infrastructure might be distracting us from another looming challenge: the risk to emerging infrastructure due to carelessness.","Title: Intrusion detection for resource-constrained embedded control systems in the power grid.\nYear: 2012\n\nAbstract: The power grid depends on embedded control systems or SCADA systems to function properly. Securing these systems presents unique challenges—in addition to the resource restrictions inherent to embedded devices, SCADA systems must accommodate strict timing requirements that are non-negotiable, and their massive scale greatly amplifies costs such as power consumption. Together, these constraints make the conventional approach to host intrusion detection–using a hypervisor to create a safe environment from which a monitoring entity can operate–too costly or impractical for embedded control systems in the critical infrastructure.","Title: Measuring the security impacts of password policies using cognitive behavioral agent-based modeling\nYear: 2015\n\nAbstract: Agent-based modeling can serve as a valuable asset to security personnel who wish to better understand the security landscape within their organization, especially as it relates to user behavior and circumvention. In this paper, we argue in favor of cognitive behavioral agent-based modeling for usable security, report on our work on developing an agent-based model for a password management scenario, perform a sensitivity analysis, which provides us with valuable insights into improving security (e.g., an organization that wishes to suppress one form of circumvention may want to endorse another), and provide directions for future work.","Title: Security and Cognitive Bias: Exploring the Role of the Mind\nYear: 2012\n\nAbstract: It's hard to create and configure security technology and hard to use it after deployment. However, the human mind is a component in both security creation and use. While we technologists have spent the last 40 years building fancier machines, psychologists have spent those decades documenting ways in which human minds systematically (and predictably) misperceive things. To what extent might cognitive bias affect the usable security problem?","Title: Circumvention of Security: Good Users Do Bad Things\nYear: 2013\n\nAbstract: Conventional wisdom is that the textbook view describes reality, and only bad people (not good people trying to get their jobs done) break the rules. And yet it doesn't, and good people circumvent.","Title: Validating an Agent-Based Model of Human Password Behavior.\nYear: 2016\n\nAbstract: Effective reasoning about the impact of security policy decisions requires understanding how human users actually behave, rather than assuming desirable but incorrect behavior. Simulation could help with this reasoning, but it requires building computational models of the relevant human behavior and validating that these models match what humans actually do. In this paper we describe our progress on building agent-based models of human behavior with passwords, and we demonstrate how these models reproduce phenomena shown in the empirical literature.","Title: I Am Joe's Fridge: Scalable Identity in the Internet of Things\nYear: 2016\n\nAbstract: Most visions of the emerging Internet of Things (IoT) distribute massive numbers of devices throughout physical infrastructure. In most visions, these devices need to talk to each other. For this to work, the devices need to be able to authenticate each other. Presenting design issues and empirical results, this paper explores the cryptographic infrastructure necessary to capture this identity ontology.","Title: Implementing a vertically hardened DNP3 control stack for power applications\nYear: 2016\n\nAbstract: We present an assurance methodology for producing significantly more secure implementations of SCADA/ICS protocols, and describe our case study of applying it to DNP3, in the form of a filtering proxy that deeply and exhaustively validates DNP3 messages. Unlike the vast majority of deployed proprietary DNP3 implementations, our code demonstrates resilience to state-of-the-art black-box as well as white-box fuzz-testing tools.","Title: Solving the Grid Defenderźs Dilemma: Tamper Protection for Distributed Cyber-Physical Systems\nYear: 2015\n\nAbstract: Embedded devices installed as part of the smart grid rollout present a major dilemma for grid defenders, because they are soft targets that could allow an attacker to access critical assets (generators, control centers, etc.) deeper in the utilityâs network. While both physical tampering and intrusion protection are large, well-studied fields, state-of-the-art protection schemes suffer from several flaws: They are not powerful enough to respond properly to different tamper events, their severe responses can lead to reduced grid availability, and they often require more setup resources than a utility operator can provide. To protect these networks, we present TEDDI (Tamper Event Detection on Distributed Infrastructure), a distributed, sensor-based tamper protection architecture for embedded devices on utility networks. TEDDI uses data gathered from across the network to make more-informed and more-accurate tamper decisions, and can customize its response based on the event it sees. It can also be configured and installed quickly, without needing a large base of knowledge beforehand. In this paper, we lay out the TEDDI architecture, and discuss how TEDDI solves the grid defenderâs dilemma better than current work.","Title: Protecting Against Malicious Bits On the Wire: Automatically Generating a USB Protocol Parser for a Production Kernel.\nYear: 2017\n\nAbstract: Recent efforts to harden hosts against malicious USB devices have focused on the higher layers of the protocol. We present a domain-specific language (DSL) to create a bit-level model of the USB protocol, from which we automatically generate software components that exhaustively validate the bit-level syntax of protocol messages. We use these generated components to create a stateful, connection-tracking firewall for USB. We integrate this firewall with the FreeBSD kernel and demonstrate that it achieves complete mediation of USB traffic, thus protecting the rest of the kernel, including higher-level policy mechanisms such as USBFilter, from low-level attacks via maliciously crafted packets. In addition to in-kernel data structures and packet validation routines, our system generates a user-level policy engine that allows for flexible and expressive firewall behavior beyond mere message syntax validation, as well as functions for pretty-printing packets (which can be used in both the kernel and in protocol analysis software). We use a Haskell back-end to generate C code that we integrate with the FreeBSD kernel, thus making our entire system amenable to formal verification.","Title: PhasorSec: Protocol Security Filters for Wide Area Measurement Systems\nYear: 2018\n\nAbstract: The addition of synchrophasors to the power grid to improve observability comes at the cost of an increased attack surface: the wide area measurement system. A common source of zero-days, that can be used to exploit the system, is improper input validation. The strict availability and timing requirements of the grid make it critical that input validation be done right and in a timely fashion. PhasorSec is a hardened security filter for the synchrophasor communication protocol, C37.118. PhasorSec is built using language theoretic principles which treat all input as a language with a specific grammar that defines what input must be accepted. An open-source version of the prototype is provided and evaluation in terms of CPU-time show that it is possible to meet the strict latency requirements. Experiments also demonstrate its effectiveness against the state-of-the-art AFL fuzzer.","Title: Going Dark: A Retrospective on the North American Blackout of 2038\nYear: 2018\n\nAbstract: From March 29, 2038, to April 6, 2038, the world observed the North American Blackout of 2038. The blackout left upwards of 300 million people without power, ravaged the world economy, and devastated the global internet. By many accounts, it was the most devastating blackout ever witnessed. That said, its occurrence should not be surprising. While pundits harp on the technical sophistication of the adversary, debate the merits of a kinetic response, and politicize the blackout, the sad reality is that we have, for years, known we were susceptible to such an event. Moreover, we have had the requisite knowledge and tools to avert the blackout, but failed to use them. Plenty has been written on the wide-reaching societal effects of the blackout; our focus will be on the blackout itself.\n\nThe Blackout of 2038 had two major phases. In the first phase, an active adversary exploited a vulnerability in the implementation of the Wireless Access in SCADA Environment (WASE) protocol suite that supports the grid. Grid operators acted swiftly and switched to a fallback system to restore power. Unfortunately, the adversary then subverted the fallback system by exploiting a well-known vulnerability in DNP3, a popular industrial control system protocol. The led to the second blackout. Eventually, a patched implementation of the WASE protocol suite was developed and deployed, which restored power.\n\nIn hindsight, this blackout stemmed from two erroneous assumptions. First, immediately following the Texas Brownout of 2020, academics, industry professionals, regulators, and other stakeholders advocated for the adoption of a protocol that was formally verified to protect against race conditions (i.e., the cause of the brownout). However, it was wrong to equate formal verification with perfect security; we should have heeded the adage from Donald Knuth, \"[b]eware of bugs in the above code; I have only proved it correct, not tried it.\" Second, we wrongly assumed a known-to-be-insecure fallback system would be an adequate stopgap until the primary system was back online.\n\nThis paper serves as a postmortem to the North American Blackout of 2038. We analyze how the failures came to pass and the assumptions that underlie them. Moreover, we offer a complete and simple solution to prevent these conditions from ever arising again: the adoption of Language-theoretic Security (LangSec) principles. To this end, we provide and evaluate a preliminary implementation of a LangSec parser for the WASE Short Message Protocol format (WSMP). Additionally, we urge lawmakers and regulatory agencies to mandate the verification of fallback protocols.","Title: Improving DES coprocessor throughput for short operations\nYear: 2001\n\nAbstract: Over the last several years, our research team built a commercially-offered secure coprocessor that, besides other features, offers high-speed DES: over 20 megabytes/second. However, it obtains these speeds only on operations with large data lengths. For DES operations on short data (e.g., 8-80 bytes), our commercial offering was benchmarked at less than 2 kilobytes/second. The programmability of our device enabled us to investigate this issue, identify and address a series of bottlenecks that were not initially apparent, and ultimately bring our short-DES performance close to 3 megabytes/second. This paper reports the results of this real-world systems exercise in hardware cryptographic acceleration--and demonstrates the importance of, when designing specialty hardware, not overlooking the software aspects governing how a device can be used.","Title: Research Report: Parsing PEGs with Length Fields in Software and Hardware\nYear: 2021\n\nAbstract: Since parsers are the line of defense between binaries and untrusted data, they are some of the most common sources of vulnerabilities in software. Language-Theoretic Security provides an approach to implement hardened parsers. We specify the binary format as a formal grammar and implement a recognizer for this formal grammar. However, most binary formats use constructs such as the length field, repeat field, and an offset instruction. Most grammar formats do not support these features. Building on PEGs and calc-regular languages, we propose Calc-Parsing Expression Grammars (Calc-PEGs), a formalization of parsing expression grammars that supports the length field. We design an algorithm to parse Calc-PEGs in $O(n^{2})$ time and a parallel algorithm to parse Calc-PEGs in O(n) time. We also present Pegmatite, a tool to generate these parsers in C, with an option to generate VHDL code.","Title: Capturing the iccMAX calculatorElement: A Case Study on Format Design\nYear: 2022\n\nAbstract: ICC profiles are widely used to provide faithful digital color reproduction across a variety of devices, such as monitors, printers, and cameras. In this paper, we document our efforts on reviewing and identifying security issues with the calculatorElement description from the recent iccMAX specification (ICC.2:2019), which expands upon the ICC v4 specification (ICC.1:2010). The iccMAX calculatorElement, which captures a calculator function through a stack-based computational approach, was designed with security in mind. We analyzed the iccMAX calculatorElement using a variety of approaches that utilized: the proof assistant PVS, the theorem-proving language ACL2, the data description language DaeDaLus, and tools tied to the data description language Parsley. Bringing the tools of formal data description, theorem proving, and static analysis to a non-trivial real-world specification has shed light on both the tools and the specification. This exercise has led us to discover numerous bugs within the specification, to identify specification improvements, to identify flaws with a demo implementation, and to recognize ways that we can improve our own tools. Additionally, this particular case study has broader implications for those who work with specification, data description languages, and parsers. In this paper, we document our work on this exercise and relay our key findings."],"string":"[\n \"Title: PorKI: Making User PKI Safe on Machines of Heterogeneous Trustworthiness\\nYear: 2005\\n\\nAbstract: As evidenced by the proliferation of phishing attacks and keystroke loggers, we know that human beings are not wellequipped to make trust decisions about when to use their passwords or other personal credentials. Public key cryptography can reduce this risk of attack, because authentication using PKI is designed to not give away sensitive data. However, using private keys on standard platforms exposes the user to \\\"keyjacking\\\"; mobile users wishing to use keypairs on an unfamiliar and potentially untrusted workstation face even more obstacles. In this paper we present the design and prototype of PorKI, a software application for mobile devices that offers an alternative solution to the portable key problem. Through the use of temporary keypairs, proxy certificates, and wireless protocols, PorKI enables a user to employ her PKI credentials on any Bluetoothenabled workstation, including those not part of her organization's network, and even those that might be malicious. Moreover, by crafting XACML policy statements that limit the key usage to the workstation's trustworthiness level, and inserting these statements into extensions of the proxy certificates, PorKI provides the user or the relying party with the ability to limit the amount of trust that can be put in the temporary keypair used on that workstation, and thus the scope of a potential compromise.\",\n \"Title: PEACHES and Peers\\nYear: 2008\\n\\nAbstract: How to distribute resource locators is a fundamental problem in PKI. Our PKI Resource Query Protocol (PRQP), recently presented at IETF, provides a standard method to query for PKI resources locators. However the distribution of locators across PKIs is still an unsolved problem. In this paper, we propose an extension to PRQP in order to distribute\\n PRQP messages over a Peer-to-Peer (P2P) network. In this work, we combine PRQP with Distributed Hash Tables (DHTs) to efficiently distribute contents over a dynamic P2P overlay network. In particular we present the PEACH protocol and a PEACH Enabled System (PEACHES) which are specifically targeted toward solving the PKI resources discovery problem. Our work enhances interoperability between\\n existing PKIs and allows for easy configuration of applications, thus augmenting usability of PKI technology.\",\n \"Title: Api-do: Tools for Exploring the Wireless Attack Surface in Smart Meters\\nYear: 2012\\n\\nAbstract: Security will be critical for the wireless interface offered by soon-to-be-ubiquitous smart meters -- since if not secure, this technology will provide an remotely accessible attack surface distributed throughout many homes and businesses. However, history shows that new network interfaces remained brittle and vulnerable (although believed otherwise) until security researchers could thoroughly explore their attack surface. Unfortunately, for the majority of currently available smart meter wireless networking solutions, we are still in that pre-exploration phase, \\\"closed\\\" radio stacks with proprietary features impede exploration by posing multiple hardware and software obstacles to standard network attack surface exploration techniques. In this paper, we address this problem by presenting open and extensible software tools for 802.15.4-based proprietary stacks that work on commodity digital radio platforms. We hope this contribution advances the state of the art beyond the pre-exploration tipping point, and toward real security.\",\n \"Title: Modeling and evaluation of certification path discovery in the emerging global PKI\\nYear: 2006\\n\\nAbstract: Establishing trust on certificates across multiple domains requires an efficient certification path discovery algorithm. Previously, small exmaples are used to analyze the performance of certification path discovery. In this work, we propose and implement a simulation framework and a probability search tree model for systematic performance evaluation. Built from measurement data collected from current PKI systems in development and deployment over more than 10 countries, our model is (to the best of our knowledge) the largest simulated PKI architecture to-date.\",\n \"Title: Small, stupid, and scalable: secure computing with faerieplay\\nYear: 2010\\n\\nAbstract: How can Agnes trust a computation C occurring at Boris's computer? In particular, how can Agnes can trust that C is occurring without Boris even being able to observe its internal state? One way is for Agnes to house C in a strong tamper-protected secure coprocessor at Boris's site. However, this approach is not scalable: neither in terms of computation - once C gets larger than the coprocessor, it becomes vulnerable to Boris again - nor in terms of cost. In this paper, we report on our Faerieplay project: rather than worrying about the limited size of a secure coprocessor, we try to make it as small as possible, with limited RAM and CPU. We start with the Fairplay work of Malkhi et al on implementing Yao's blinded-circuit solution to secure multiparty computation with software - this permits Agnes to trust C, but is too inefficient for all but small C. We then use our own prior work on using trusted third parties for practical Private Information Retrieval to design and prototype tiny trusted third parties (TTTPs) that substantially reduce the overhead involved in blind circuit evaluation.\",\n \"Title: The dartmouth green grid\\nYear: 2005\\n\\nAbstract: The Green Grid is an ambitious project to create a shared high performance computing infrastructure for science and engineering at Dartmouth College. The Green Grid was created with the support of the Dean of the Faculty of Arts & Sciences to promote collaborative computing for the entire Dartmouth community. We will share our design for building campus grids and experiences in Grid-enabling applications from several academic departments.\",\n \"Title: The cake is a lie: privilege rings as a policy resource\\nYear: 2009\\n\\nAbstract: Components of commodity OS kernels typically execute at the same privilege level. Consequently, the compromise of even a single component undermines the trustworthiness of the entire kernel and its ability to enforce separation between user-level processes. Reliably containing the extent of a compromised kernel component is a problem to which few practical solutions exist. While many approaches have been proposed to reduce the need to trust large portions of the kernel, most of these approaches represent exotic reorganizations of the hardware or OS kernel that are either not applicable to commodity systems or are relatively complex and difficult to debug in their own right (e.g., microkernels). We propose simple, natural modifications to commodity---x86---hardware that enable vertical isolation down through the kernel without the use of virtualization or major OS rewrites; specifically, extending and reinterpreting the x86 segmentation mechanism, extending the existing Current Privilege Level and Descriptor Privilege Level fields. We believe our proposal is a compelling alternative to traditional virtualization because the hardware virtualizes permissions, not I/O.\",\n \"Title: VM-based security overkill: a lament for applied systems security research\\nYear: 2010\\n\\nAbstract: Virtualization has seen a rebirth for a wide variety of uses; in our field, systems security researchers routinely use it as a standard tool for providing isolation and introspection. Researchers' use of virtual machines has reached a level of orthodoxy that makes it difficult for the collective wisdom to consider alternative approaches to protecting computation. We suggest that many scenarios exist where virtual machines do not provide a suitable tool or appropriate security properties. We analyze the use of virtual machines in the systems security space and we highlight other work that questions the current (ab)uses of virtualization. The takeaway message of this paper is that 'self-protection' mechanisms still represent an interesting and viable path of research. At some point, hypervisors (or whatever the lowest layer of software, firmware, or programmable hardware is) must rely on detection and protection mechanisms embedded within themselves.\",\n \"Title: Protecting Client Privacy with Trusted Computing at the Server\\nYear: 2005\\n\\nAbstract: Current trusted-computing initiatives usually involve large organizations putting physically secure hardware on user machines, potentially violating user privacy. Yet, it's possible to exploit robust server-side secure hardware to enhance user privacy. Two case studies demonstrate using secure coprocessors at the server.\",\n \"Title: Attribute-Based Publishing with Hidden Credentials and Hidden Policies\\nYear: 2007\\n\\nAbstract: With Hidden Credentials Alice can send policy- encrypted data to Bob in such a way that he can decrypt the data only with the right combination of credentials. Alice gains no knowledge of Bob's credentials in the process, and hence the name \\\"Hidden Credentials.\\\" Research on Hidden Credential systems has focused on messages sent to single recipients, where the sender needs to know the recipient's pseudonym beforehand, and on Hidden Policies, where Bob learns as little information as possible about Alice's pol- icy for decrypting the message. Current schemes provide weak policy privacy — with non-interactive schemes, the recipient can learn parts of the policy, and with interac- tive schemes based on secure multiparty computation, a user can try different sets of credentials as input to gain knowledge of the policy after repeated decryption attempts. Furthermore, existing schemes do not support policies with negations efficiently. For example, a policy stating \\\"Bob is not a student\\\" is hard to enforce since Bob can simply withhold, or not use, his student credential. We propose a system called PEAPOD (Privacy- Enhanced Attribute-based Publishing Of Data) that pro- vides the following properties: (1) Users can securely pub- lish data protected by attribute-based policies to multiple possible recipients without requiring interaction between senders and receivers. This is achieved by using a semi- trusted server. (2) The plaintext message and the policy are completely hidden from the server. (3) Any recipient, intended or not, learns no other information about a mes- sage's policy beyond the number of clauses in policy that were satisfied. Furthermore the recipient is forced to use allof his or her issued credentials for decryption, and there- fore cannot mount inference attacks by trying to decrypt the\",\n \"Title: ABUSE: PKI for real-world email trust\\nYear: 2009\\n\\nAbstract: Current PKI-based email systems (such as X.509 S/MIME and PGP/ MIME) potentially enable a recipient to determine a name and organizational affiliation of the sender. This information can suffice for a trust decision when the recipient already knows the sender--but how can a recipient decide whether or not trust email from a new correspondent? Current systems are not expressive enough to capture the real ways that trust flows in these sorts of scenarios. To solve this problem, we begin by applying concepts from social science research to a variety of such cases from interesting application domains; primarily, crisis management in the North American power grid. We have examined transcripts of telephone calls made between grid management personnel during the August 2003 North American blackout and extracted several different classes of trust flows from these real-world scenarios. Combining this knowledge with some design patterns from HCISEC, we develop criteria for a system that will enable humans apply these same methods of trust-building in the digital world. We then present the design and prototype of Attribute-Based, Usefully Secure Email (ABUSE)--and present experimental evaluation showing that it solves the problem.\",\n \"Title: Katana: A Hot Patching Framework for ELF Executables\\nYear: 2010\\n\\nAbstract: Despite advances in software modularity, security, and reliability, offline patching remains the predominant form of updating or protecting commodity software. Unfortunately, the mechanics of hot patching (the process of upgrading a program while it executes) remain understudied, even though such a capability offers practical benefits for both consumer and mission-critical systems. A reliable hot patching procedure would serve particularly well by reducing the downtime nec- essary for critical functionality or security upgrades. Yet, hot patching also carries the risk - real or perceived - of leaving the system in an inconsistent state, which leads many owners to forego its benefits as too risky. In this paper, we propose a novel method for hot patching ELF binaries that supports (a) synchronized global data and code updates and (b) reasoning about the results of applying the hot patch. We propose a format, which we call a Patch Object, for encoding patches as a special type of ELF relocatable object file. Our tool, Katana, automatically creates these patch objects as a by-product of the standard source build process. Katana also allows an end-user to apply the Patch Objects to a running process. In essence, our method can be viewed as an extension of the Application Binary Interface (ABI), and we argue for its inclusion in future ABI standards.\",\n \"Title: Using a High-Performance, Programmable Secure Coprocessor\\nYear: 1998\\n\\nAbstract: Abstract Secure coprocessors enable secure distributed applications by providing safe havens where an application program can execute (and accumulate state), free of observation and interference by an adversary with direct physical access to the device. However, for these coprocessors to be effective, participants in such applications must be able to verify that they are interacting with an authentic program on an authentic, untampered device. Furthermore, secure coprocessors that support general-purposecomputation,and will be manufactured,and distributed as commercial,productsmust provide these core sanctuary and authentication properties while also meeting many additional challenges, including: the applications, operating system, and underlying security management may all come from different, mutually suspicious authorities; configuration and maintenance must occur in a hostile environment, while minimizing disruption of operations; the device must be able to recover from the vulnerabilities that inevitably emerge in complex,software; physical security dictates that the device itself can never be opened,and examined; and ever-evolving cryptographic requirements dictate that hardware,accelerators be supported by reloadable on-card software. This paper summarizes the hardware, software, and cryptographic architecture we developed to address these problems. Furthermore, with our colleagues, we have implemented this solution, into a commercially available product. DRAFT Contents\",\n \"Title: Electronic prescription for controlled substances: a cybersecurity perspective\\nYear: 2013\\n\\nAbstract: The Electronic Prescription for Controlled Substances (EPCS) is a set of rules published by the Drug Enforcement Administration (DEA) that regulates implementations of electronic prescription systems for controlled substances [1]. EPCS includes requirements two-factor authentication; specifications for electronic prescription applications; and rules governing the signing, transmitting, and receiving of electronic prescriptions [1]. However, this set of regulations overlooks numerous critical aspects of computer security. This paper highlights some key areas in the electronic prescription process outlined by the EPCS regulation that are susceptible to adversarial attacks and provides recommendations for additions to EPCS regulations that would provide greater security for the use of electronic prescriptions.\",\n \"Title: Interoperable Pki Data Distribution In Computational Grids\\nYear: 2009\\n\\nAbstract: One of the most successful working examples of virtual organizations, computational grids need authentication mechanisms that inter-operate across domain boundaries. Public Key Infrastructures (PKIs) provide sufficient flexibility to allow resource managers to securely grant access to their systems in such distributed environments. However, as PKIs grow and services are added to enhance both security and usability, users and applications must struggle to discover available resources-particularly when the Certification Authority (CA) is alien to the relying party. This article presents how to overcome these limitations of the current grid authentication model by integrating the PKI Resource Query Protocol (PRQP) into the Grid Security Infrastructure (GSI).\",\n \"Title: High Security With Low Latency In Legacy Scada Systems\\nYear: 2010\\n\\nAbstract: Message authentication with low latency is necessary to ensure secure operations in legacy industrial control networks such as those in the power grid. Previous authentication solutions that examine single messages incur noticeable latency. This paper describes Predictive YASIR, a bump-in-the-wire device that reduces the latency by considering broader patterns of messages. The device predicts the incoming plaintext based on previous observations; compresses, encrypts and authenticates data online; and pre-sends a portion of the ciphertext before receiving the entire plaintext. The performance of Predictive YASIR is evaluated using a simulation involving the Modbus/ASCII protocol. By considering broader message patterns and using predictive analysis, improvements in latency of 15.48 +/- 0.35% are obtained.\",\n \"Title: PPAA: Peer-to-Peer Anonymous Authentication\\nYear: 2008\\n\\nAbstract: In the pursuit of authentication schemes that balance user privacy and accountability, numerous anonymous credential systems\\n have been constructed. However, existing systems assume a client-server architecture in which only the clients, but not the\\n servers, care about their privacy. In peer-to-peer (P2P) systems where both clients and servers are peer users with privacy\\n concerns, no existing system correctly strikes that balance between privacy and accountability.\\n \\n In this paper, we provide this missing piece: a credential system in which peers are pseudonymous to one another (that is, two who interact more than once can recognize each other via pseudonyms) but are otherwise anonymous\\n and unlinkable across different peers. Such a credential system finds applications in, e.g., Vehicular Ad-hoc Networks (VANets)\\n and P2P networks.\\n \\n \\n \\n We formalize the security requirements of our proposed credential system, provide a construction for it, and prove the security\\n of our construction. Our solution is efficient: its complexities are independent of the number of users in the system.\",\n \"Title: Private Information Storage With Logarithmic-Space Secure Hardware\\nYear: 2004\\n\\nAbstract: In Private Information Retrieval (PIR), a user obtains one of N records from a server, without the server learning what record was requested.Recent research in \\\"practical PIR\\\" has limited the players to the user and server and limited the user's work to negotiating a session key (eg. as in SSL)but then added a secure coprocessor to the server and required the secure coprocessor to encrypt/permute the dataset (and often gone ahead and built real systems).Practical PIR (PPIR) thus consists of trying to solve a privacy problem for a large dataset using the small internal space of the coprocessor. This task is very similar to the one undertaken by the older Oblivious RAMs work, and indeed the latest PPIR work uses techniques developed for Oblivious RAMs. Previous PPIR work had two limitations: the internal space required was still O(N1g N) bits, and records could only be read privately, not written.In this paper, we present a design and experimental results that overcome these limitations. We reduce the internal memory to O(1g N) by basing the pseudorandom permutation on a Luby-Rackoff style block cipher, and by redesigning the oblivious shuffle to reduce space requirements and avoid unnecessary work. This redesign yields both a time and a space savings. These changes expand the system's applicability to larger datasets and domains such as private file storage.These results have been implemented for the IBM 4758 secure coprocessor platform, and are available for download.\",\n \"Title: Evaluation of efficient security for BGP route announcements using parallel simulation\\nYear: 2004\\n\\nAbstract: The Border Gateway Protocol (BGP) determines how Internet traffic is routed throughout the entire world; malicious behavior by one or more BGP speakers could create serious security issues. Since the protocol depends on a speaker honestly reporting path information sent by previous speakers and involves a large number of independent speakers, the Secure BGP (S-BGP) approach uses public-key cryptography to ensure that a malicious speaker cannot fabricate this information. However, such public-key cryptography is expensive: S-BGP requires a digital signature operation on each announcement sent to each peer, and a linear (in the length of the path) number of verifications on each receipt. We use simulation of AS models derived from the Internet to evaluate the impact that the processing costs of cryptography have on BGP convergence time. As the size of these models grows, inherent memory requirements grow beyond what is normally available in serial computers, motivating us to use distributed memory cluster computers, just to hold the model state. We find that under heavy load the convergence time using ordinary S-BGP is significantly larger than BGP. We examine the impact of highly aggressive caching and pre-computation optimizations for S-BGP, and find that convergence time is much closer to BGP. However, these optimizations may be unrealistic, and are certainly expensive of memory. We consequently use the structure of BGP processing to design optimizations that reduce cryptographic overhead by amortizing the cost of private-key signatures over many messages. We call this method Signature-Amortization (S-A). We find that S-A provides as good or better convergence times as the highly optimized S-BGP, but without the cost and complications of caching and pre-computation. These experiments––whose memory demands easily exceed 10Gb––are made possible using parallel simulation. They show that it is is possible therefore to minimize the impact route validation has on convergence, by being careful with signatures, rather than consumptive of memory.\",\n \"Title: Secure cryptographic precomputation with insecure memory\\nYear: 2008\\n\\nAbstract: We propose a solution that provides secure storage for cryptographic precomputation using insecure memory that is susceptible to eavesdropping and tampering. Specifically, we design a small tamper-resistant hardware module, the Queue Security Proxy (QSP), that situates transparently on the data-path between the processor and the insecure memory. Our analysis shows that our design is secure and flexible, and yet efficient and inexpensive. In particular, both the timing overhead and the hardware cost of our solution are independent of the storage size.\",\n \"Title: Extending PKI Interoperability in Computational Grids\\nYear: 2008\\n\\nAbstract: One of the most successful working examples of virtualor ganizations, computational grids need authentication mechanisms that inter-operate across domain boundaries. Public Key Infrastructures (PKIs) provide sufficient flexibility to allow resource managers to securely grant access to their systems in such distributed environments. However, as PKIs grow and services are added to enhance both security and usability, users and applications must struggle to discover available resources—particularly when the Certification Authority (CA) is alien to the relying party. This paper presents how to overcome these limitations of the current grid authentication model by integrating the PKI Resource Query Protocol (PRQP) into the Grid Security Infrastructure (GSI).\",\n \"Title: Building a high-performance, programmable secure coprocessor\\nYear: 1999\\n\\nAbstract: Secure coprocessors enable secure distributed applications by providing safe havens where an application program can execute (and accumulate state), free of observation and interference by an adversary with direct physical access to the device. However, for these coprocessors to be effective, participants in such applications must be able to verify that they are interacting with an authentic program on an authentic, untampered device. Furthermore, secure coprocessors that support general-purpose computation and will be manufactured and distributed as commercial products must provide these core sanctuary and authentication properties while also meeting many additional challenges, including: • the applications, operating system, and underlying security management may all come from different, mutually suspicious authorities; • configuration and maintenance must occur in a hostile environment, while minimizing disruption of operations; • the device must be able to recover from the vulnerabilities that inevitably emerge in complex software; • physical security dictates that the device itself can never be opened and examined; and • ever-evolving cryptographic requirements dictate that hardware accelerators be supported by reloadable on-card software. This paper summarizes the hardware, software, and cryptographic architecture we developed to address these problems. Furthermore, with our colleagues, we have implemented this solution, into a commercially available product.\",\n \"Title: AutoPKI: a PKI resources discovery system\\nYear: 2007\\n\\nAbstract: The central goal of Public Key Infrastructure (PKI) is to enable trust judgments between distributed users. Although certificates play a central role in making such judgments, a PKI's users need more than just knowledge of certificates. Minimally, a relying party must able to locate critical parameters such the certificate repositories and certificate validation servers relevant to the trust path under consideration. Users in other scenarios may require other resources and services. Surprisingly, locating these resources and services remains a largely unsolved problem in real-world X.509 PKI deployment. In this paper, we present the design and prototype of a new and flexible solution for automatic discovery of the services and data repositories are available from a Certificate Service Provider (CSP). This contribution will take real-world PKI one step closer to achieving its goal.\",\n \"Title: XUTools: UNIX commands for processing next-generation structured text\\nYear: 2012\\n\\nAbstract: Traditional Unix tools operate on sequences of characters, bytes, fields, lines, and files. However, modern practitioners often want to manipulate files in terms of a variety of language-specific constructs--C functions, Cisco IOS interface blocks, and XML elements, to name a few. These language-specific structures quite often lie beyond the regular languages upon which Unix text-processing tools can practically compute. In this paper, we propose eXtended Unix text-processing tools (xutools) and present implementations that enable practitioners to extract (xugrep), count (xuwc), and compare (xudiff) texts in terms of language-specific structures. We motivate, design, and evaluate our tools around real-world use cases from network and system administrators, security consultants, and software engineers from a variety of domains including the power grid, healthcare, and education.\",\n \"Title: Why Do Street-Smart People Do Stupid Things Online?\\nYear: 2008\\n\\nAbstract: The current epidemic of poor trust decisions by users online is largely due to flaws in GUIs that train the users away from using real-world security intuitions. The authors propose a principle for GUI designers that will help them avoid such design mistakes.\",\n \"Title: BLAC: Revoking Repeatedly Misbehaving Anonymous Users without Relying on TTPs\\nYear: 2010\\n\\nAbstract: Several credential systems have been proposed in which users can authenticate to service providers anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a Trusted Third Party (TTP). The ability of the TTP to revoke a user’s privacy at any time, however, is too strong a punishment for misbehavior. To limit the scope of deanonymization, some systems have been proposed in which users can be deanonymized only if they authenticate “too many times,” such as “double spending” with electronic cash. While useful in some applications, such techniques cannot be generalized to more subjective definitions of misbehavior, for example, using such schemes it is not possible to block anonymous users who “deface too many Web pages” on a Web site. We present BLAC, the first anonymous credential system in which service providers can revoke the credentials of misbehaving users without relying on a TTP . Since revoked users remain anonymous, misbehaviors can be judged subjectively without users fearing arbitrary deanonymization by a TTP . Additionally, our construction supports a d-strikes-out revocation policy, whereby users who have been subjectively judged to have repeatedly misbehaved at least d times are revoked from the system. Thus, for the first time, it is indeed possible to block anonymous users who have “defaced too many Web pages” using our scheme.\",\n \"Title: Design and Prototype of a Coercion-Resistant, Verifiable Electronic Voting System\\nYear: 2004\\n\\nAbstract: In elections, it is important that voters be able to verify that the tally reflects the sum of the votes that were actually cast, as they were intended to be cast. It is also important that voters not be subject to coercion from adversaries. Currently most proposed voting systems fall short: they either do not provide both properties, or require the voter to be a computer. In this paper, we present a new voting system that uses voter knowledge to allow voter verification by using a receipt that is uninformative for a coercer without access to the voting machine or the contents of the cast ballots. Our system does not assume any trust in the voting machine, but requires a few other assumptions which we believe to be reasonable in the real-world situation. A basic prototype of this system is available on our website. I. INTRODUCTION The US presidential elections of 2000 made the general public aware of the problems of producing a voting system that could be trusted by the voters to submit their votes correctly. Despite the public review and control of the US electoral system, many US citizens felt that the system had failed them. Although the problems did not originate in the 2000 election, the situation where a very small number of votes was sufficient to flip the final tally raised the public's awareness of the inadequacy of the system. The problem of producing a fair voting system has been well-known in countries and situations where adversaries have a very high degree of control. In totalitarian societies (or other situations with almost complete adversarial control), it may be futile to attempt to solve this problem. Such societies provide no guarantee that the adversary will comply with the solution, no guarantee that the observers and complainants will be able to speak up, and no guarantee that the situation will be corrected even if there is a valid complaint. However, in a free democratic society in the 21st century, the electoral system is subject to public review and control. Its failures do not have to be possible. If an electronic voting system is to be applied in secret- ballot elections, it has to be receipt-free, i.e. not allow a voter to carry away any evidence of who he voted for, since such evidence would permit vote buying and coercion. Receipt- freeness is hard to combine with voter verifiability: if a voter is able to verify that his vote was counted as he cast it, what could prevent him from proving how he voted to a third party? Cryptography can help address this seeming incompatibility between receipt-freeness and voter verifiability, if the voter has an encrypted copy of his vote and can verify that his encrypted vote made it to the final tally. However, that requires the voter to be able to verify that the encryption of his vote is correct. Chaum's layered receipts (5) (discussed below) solve this problem partially: they allow verification, but only with probability 50%. In this paper, we examine these properties and survey the principal current approaches to electronic voting systems. We then present a new design that improves on the previous work, by being (arguably) the first one that achieves both voter verifiability and coercion resistance, while not assuming the voter is a computer, not relying on correct behavior by the voting machine, and detecting close to 100% of misbehaviour. Section II briefly discusses the requirements for a secure election system. Section III presents a brief overview of methods used in receipt-free election schemes. Section IV discusses the most recently implemented election schemes. Section V presents our election scheme. Section VI discusses the practical applicability of our scheme. Section VII describes our prototype. Section VIII offers some concluding remarks.\",\n \"Title: Trusting trusted hardware: towards a formal model for programmable secure coprocessors\\nYear: 1998\\n\\nAbstract: Secure coprocessors provide a foundation for many exciting electronic commerce applications, as previous work [20, 21] has demonstrated. As our recent work [6, 13, 14] has explored, building a high-end secure coprocessor that can be easily programmed and deployed by a wide range of third parties can be an important step toward realizing this promise. But this step requires trusting trusted hardware-and achieving this trust can be difficult in the face of a problem and solution space that can be surprisingly complex and subtle. Formal methods provide one means to express, verify, and analyze such solutions (and would be required for such a solution to be certified at FIPS 140-1 Level 4). This paper discusses our current efforts to apply these principles to the architecture of our secure coprocessor. We present formal statements of the security goals our architecture needs to provide; we argue for correctness by enumerating the architectural properties from which these goals can be proven; we argue for conciseness by showing how eliminating properties causes the goals to fail; but we discuss how simpler versions of the architecture can satisfy weaker security goals. We view this work as the beginning of developing formal models to address the trust challenges arising from using trusted hardware for electronic commerce.\",\n \"Title: PorKI: portable PKI credentials via proxy certificates\\nYear: 2010\\n\\nAbstract: Authenticating human users using public key cryptography provides a number of useful security properties, such as being able to authenticate to remote party without giving away a secret. However, in many scenarios, users need to authenticate from a number of client machines, of varying degrees of trustworthiness. In previous work, we proposed an approach to solving this problem by giving users portable devices which wirelessly issue temporary, limited-use proxy certificates to the clients. In this paper, we describe our complete prototype, enabling the use of proxy credentials issued from a mobile device to securely authenticate users to remote servers via a shared (or otherwise not trusted) device. In particular, our PorKI implementation combines out-of-band authentication (via 2D barcode images), standard Proxy Certificates, and platform attestation to provide usable and secure temporary credentials for web-based applications.\",\n \"Title: TwoKind authentication: protecting private information in untrustworthy environments\\nYear: 2008\\n\\nAbstract: Users often log in to Internet sites from insecure computers and more recently have started divulging their email passwords to social-networking sites, thereby putting their private communications at risk. We propose and evaluate TwoKind Authentication, a simple and effective technique for limiting access to private information in untrustworthy environments. In its simplest form, TwoKind offers two modes of authentication by providing a low and a high authenticator. By using a low authenticator, users can signal to the server that they are in an untrusted environment, following which the server restricts the user's actions. We seek to evaluate the effectiveness of multiple authenticators in promoting safer behavior in users. We demonstrate the effectiveness of this approach through a user experiment - we find that users make a distinction between the two authenticators and generally behave in a security-conscious way, protecting their high authenticator the ma jority of the time. Our study suggests that TwoKind will be beneficial to several Internet applications, particularly if the privileges associated with the low authenticator can be customized to a user's security preferences.\",\n \"Title: Traps, events, emulation, and enforcement: managing the yin and yang of virtualization-based security\\nYear: 2008\\n\\nAbstract: We question current trends that attempt to leverage virtualization techniques to achieve security goals. We suggest that the security role of a virtual machine centers on being a policy interpreter rather than a resource provider. These two roles (security reference monitor and resource emulator) are currently conflated within the context of virtual machines and VMMs. We believe that this ``double-duty'' leads to both a significant performance impact as well as a bloated virtualization layer. Increased complexity reduces confidence that the code is elementary enough to verify or trust from a security perspective. Ironically, as more security-related functionality is shoved into a VM platform, the system becomes less trustworthy as it becomes increasingly trusted. We argue that a principle reason for such an unfortunate situation is the lack of efficient hardware trapping mechanisms. We propose an architecture to help ameliorate this problem by transferring the security enforcement and program analysis roles from the virtualization component to a policy-directed FPGA.\",\n \"Title: \\\"Weird machines\\\" in ELF: a spotlight on the underappreciated metadata\\nYear: 2013\\n\\nAbstract: Although software exploitation historically started as an exercise in coaxing the target's execution into attacker-supplied binary shellcode, it soon became a practical study in pushing the limits of unexpected computation that could be caused by crafted data not containing any native code. We show how the ABI metadata that drives the creation of a process' runtime can also drive arbitrary computation. We introduce our design and implementation of Cobbler, a proof-of-concept toolkit capable of compiling a Turing-complete language into well-formed ELF executable metadata that get \\\"executed\\\" by the runtime loader (RTLD). Our proof-of-concept toolkit highlights how important it is that defenders expand their focus beyond the code and data sections of untrusted binaries, both in static analysis and in the dynamic analysis of the early runtime setup stages as well as any time the RTLD is invoked.\",\n \"Title: Using active intrusion detection to recover network trust\\nYear: 2011\\n\\nAbstract: Most existing intrusion detection systems take a passive approach to observing attacks or noticing exploits. We suggest that active intrusion detection (AID) techniques provide value, particularly in scenarios where an administrator attempts to recover a network infrastructure from a compromise. In such cases, an attacker may have corrupted fundamental services (e.g., ARP, DHCP, DNS, NTP), and existing IDS or auditing tools may lack the precision or pervasive deployment to observe symptoms of this corruption. We prototype a specific instance of the active intrusion detection approach: how we can use an AID mechanism based on packet injection to help detect rogue services.\",\n \"Title: Combating spam and denial-of-service attacks with trusted puzzle solvers\\nYear: 2008\\n\\nAbstract: Cryptographic puzzles can be used to mitigate spam and denial-of-service (DoS) attacks, as well as to implement timed-release cryptography. However, existing crypto puzzles are impractical because: (1) solving them wastes computing resources and/or human time, (2) the time it takes to solve them can vary dramatically across computing platforms, and/or (3) applications become non-interoperable due to competition for resources when solving them. We propose the use of Trusted Computing in constructing crypto puzzles. Our puzzle constructions have none of the drawbacks above and only require each client machine to be equipped with a small tamper-resistant Trusted Puzzle Solver (TPS), which may be realized using the prevalent Trusted Platform Module (TPM) with minimal modifications.\",\n \"Title: Improved learning of AC0 functions\\nYear: 1991\\n\\nAbstract: Two extensions of the Linial, Mansour, Nisan 0 learning algorithm are presented. The LMN method works when input examples are drawn uniformly. The new algorithms improve on theirs by performing well when given inputs drawn from unknown, mutually independent distribu- tions. A variant of the one of the algorithms is conjectured to work in an even broader setting.\",\n \"Title: Cryptographic scalability challenges in the smart grid (extended abstract)\\nYear: 2012\\n\\nAbstract: In the envisioned smart grid, massive numbers of computational devices will need to authenticate to each other. For scalability, this technology will probably rest on public-key infrastructure (PKI). However, deploying PKI on an entity population this large -- and doing the kinds of things we envision the smart grid doing -- itself raises many scalability challenges the community will need to address. We survey some.\",\n \"Title: Katana: Towards Patching as a Runtime Part of the Compiler-Linker-Loader Toolchain\\nYear: 2010\\n\\nAbstract: The mechanics of hot patching the process of upgrading a program while it executes remain understudied, even though it offers capabilities that act as practical benefits for both consumer and mission-critical systems. A reliable hot patching procedure would serve particularly well by reducing the downtime necessary for critical functionality or security upgrades. However, hot patching also carries the risk-real or perceived-of leaving the system in an inconsistent state, which leads many owners to forgo its benefits as too risky; for systems where availability is critical, this decision may result in leaving systems un-patched and vulnerable. In this paper, the authors present a novel method for hot patching ELF binaries that supports synchronized global data and code updates, and reasoning about the results of applying the hot patch. In this regard, the Patch Object format was developed to encode patches as a special type of ELF re-locatable object file. The authors then built a tool, Katana, which automatically creates these patch objects as a by-product of the standard source build process. Katana also allows an end-user to apply the Patch Objects to a running process.\",\n \"Title: Pretending that Systems Are Secure\\nYear: 2005\\n\\nAbstract: We look at the societal aspects in this installment: the formal education process through which we train students, young and old, to be effective cyber-citizens; and the media coverage and editorializing process through which we express (or perhaps imprint) ethical judgment.\",\n \"Title: Nymble: Blocking Misbehaving Users in Anonymizing Networks\\nYear: 2011\\n\\nAbstract: Anonymizing networks such as Tor allow users to access Internet services privately by using a series of routers to hide the client's IP address from the server. The success of such networks, however, has been limited by users employing this anonymity for abusive purposes such as defacing popular Web sites. Web site administrators routinely rely on IP-address blocking for disabling access to misbehaving users, but blocking IP addresses is not practical if the abuser routes through an anonymizing network. As a result, administrators block all known exit nodes of anonymizing networks, denying anonymous access to misbehaving and behaving users alike. To address this problem, we present Nymble, a system in which servers can “blacklist” misbehaving users, thereby blocking users without compromising their anonymity. Our system is thus agnostic to different servers' definitions of misbehavior—servers can blacklist users for whatever reason, and the privacy of blacklisted users is maintained.\",\n \"Title: The page-fault weird machine: lessons in instruction-less computation\\nYear: 2013\\n\\nAbstract: Trust Analysis, i.e. determining that a system will not execute some class of computations, typically assumes that all computation is captured by an instruction trace. We show that powerful computation on ×86 processors is possible without executing any CPU instructions. We demonstrate a Turing-complete execution environment driven solely by the IA32 architecture's interrupt handling and memory translation tables, in which the processor is trapped in a series of page faults and double faults, without ever successfully dispatching any instructions. The \\\"hard-wired\\\" logic of handling these faults is used to perform arithmetic and logic primitives, as well as memory reads and writes. This mechanism can also perform branches and loops if the memory is set up and mapped just right. We discuss the lessons of this execution model for future trustworthy architectures.\",\n \"Title: Computational techniques for increasing PKI policy comprehension by human analysts\\nYear: 2010\\n\\nAbstract: Natural-language policies found in X.509 PKI describe an organization's stated policy as a set of requirements for trust. The widespread use of X.509 underscores the importance of understanding these requirements. Although many review processes are defined in terms of the semantic structure of these policies, human analysts are confined to working with page-oriented PDF texts. Our research accelerates PKI operations by enabling machines to translate between policy page numbers and policy reference structure. Adapting technologies supporting the analysis of Classical texts, we introduce two new tools. Our Vertical Variance Reporter helps analysts efficiently compare the reference structure of two policies. Our Citation-Aware HTML enables machines to process human-readable displays of policies in terms of this reference structure. We evaluate these contributions in terms of real-world feedback and observations from organizations that audit or accredit policies.\",\n \"Title: Building the IBM 4758 Secure Coprocessor\\nYear: 2001\\n\\nAbstract: The authors sought to build a secure coprocessor驴defined as a tamper-responding device derived from the Abyss, Citadel, and 4755 work驴that would provide a single multipurpose platform third parties could use to develop and deploy secure coprocessor applications, with minimal IBM participation. The project had several goals: ensure that the device could be identified externally, design the device and its soft-ware to be securely configurable and updatable in the field, construct the software architecture to accommodate layers of code from different parties, avoid letting the compromise of one device breach any other's security, and validate all these assertions through an external party.Providing an environment in which applications could run securely forced the designers to focus not only on security mechanisms and their implementation and management, but also on the security policies they must support. Clearly, the hardware on which applications run must be secure, as must the operating system and run-time environment in between, while offering a reasonable API for applications developers. To fix problems in the field and enable fast and inexpensive reaction to changing customer needs, the designers implemented part of the code as firmware rather than as read-only memory.The 4758 project achieved most of its design goals. Currently, the authors are exploring other embedded processors, the addition of a network communication channel, and other form factors, including those appropriate for laptops.\",\n \"Title: Nymble: anonymous IP-address blocking\\nYear: 2007\\n\\nAbstract: Anonymizing networks such as Tor allow users to access Internet services privately using a series of routers to hide the client's IP address from the server. Tor's success, however, has been limited by users employing this anonymity for abusive purposes, such as defacing Wikipedia. Website administrators rely on IP-address blocking for disabling access to misbehaving users, but this is not practical if the abuser routes through Tor. As a result, administrators block all Tor exit nodes, denying anonymous access to honest and dishonest users alike. To address this problem, we present a system in which (1) honest users remain anonymous and their requests unlinkable; (2) a server can complain about a particular anonymous user and gain the ability to blacklist the user for future connections; (3) this blacklisted user's accesses before the complaint remain anonymous; and (4) users are aware of their blacklist status before accessing a service. As a result of these properties, our system is agnostic to different servers' definitions of misbehavior.\",\n \"Title: Open-Source Applications of TCPA Hardware\\nYear: 2004\\n\\nAbstract: How can Alice trust computation occurring at Bob's computer? Since it exists and is becoming ubiquitous, the current-generation TCPA/TCG hardware might enable a solution. When we started investigating this technology, the specification of the TCG software stack was not publicly available, and an implementation is still not; so, we designed and built an open-source platform based on Linux and commercially available TCPA/TCG hardware which would allow us to address the problem of trusting computation. Within the limits of TCPA/TCG hardware security, our solution balances what Alice needs to do to make trust judgments against what Bob needs to do to keep his system running. Furthermore, we describe how we use our platform to harden three sample open-source applications: Apache SSL Web servers, OpenCA certification authorities, and (with SELinux) compartmented attestation to balance privacy with DRM. To our knowledge, our project remains the only open-source TCPA/TCG platform in existence, and is also enabling trusted computing applications developed by our user community (enforcer.sourceforge.net reports over 1100 sourcecode downloads so far).\",\n \"Title: The effects of introspection on creating privacy policy\\nYear: 2009\\n\\nAbstract: Prior work in psychology shows that introspection inhibits intuition: asking human users to analyze judgements they make can cause them to be quantitatively worse at making those judgments. In this paper, we explore whether this seemingly contradictory phenomenon also occurs when humans craft privacy policies for a Facebook-like social network. Our study presents empirical evidence that suggests the act of introspecting upon one's personal security policy actually makes one worse at making policy decisions; if one aims to reduce privacy spills, the data indicate that educating users before letting them set their privacy policies may actually increase the exposure of private information.\",\n \"Title: Digital signatures and electronic documents: a cautionary tale\\nYear: 2002\\n\\nAbstract: Often, the main motivation for using PKI in business environments is to streamline workflow, by enabling humans to digitally sign electronic documents, instead of manually signing paper ones. However, this application fails if adversaries can construct electronic documents whose viewed contents can change in useful ways, without invalidating the digital signature. In this paper, we examine the space of such attacks, and describe how many popular electronic document formats and PKI packages permit them.\",\n \"Title: Aggregated path authentication for efficient BGP security\\nYear: 2005\\n\\nAbstract: The Border Gateway Protocol (BGP) controls inter-domain routing in the Internet. BGP is vulnerable to many attacks, since routers rely on hearsay information from neighbors. Secure BGP (S-BGP) uses DSA to provide route authentication and mitigate many of these risks. However, many performance and deployment issues prevent S-BGP's real-world deployment. Previous work has explored improving S-BGP processing latencies, but space problems, such as increased message size and memory cost, remain the major obstacles. In this paper, we design aggregated path authentication schemes by combining two efficient cryptographic techniques---signature amortization and aggregate signatures. We propose six constructions for aggregated path authentication that substantially improve efficiency of S-BGP's path authentication on both speed and space criteria. Our performance evaluation shows that the new schemes achieve such an efficiency that they may overcome the space obstacles and provide a real-world practical solution for BGP security.\",\n \"Title: What's Wrong with Access Control in the Real World?\\nYear: 2010\\n\\nAbstract: This article enumerates some simplifying assumptions the security community has made in its effort to gain traction with the access control problem. For many environments, a dramatic and painful mismatch seems to exist between these simplifying assumptions and reality. The authors argue that effective security in these environments might therefore require rethinking these assumptions.\",\n \"Title: Completely Asynchronous Optimistic Recovery with Minimal Rollbacks\\nYear: 1995\\n\\nAbstract: Consider the problem of transparently recovering an asynchronous distributed computation when one or more processes fail. Basing rollback recovery on optimistic message logging and replay is desirable for several reasons, including not requiring synchronization between processes during failure-free operation. However, previous optimistic rollback recovery protocols either have required synchronization during recovery, or have permitted a failure at one process to potentially trigger an exponential number of process rollbacks. In this paper, we present an optimistic rollback recovery protocol that provides completely asynchronous recovery, while also reducing the number of times a process must roll back in response to a failure to at most one. This protocol is based on comparing timestamp vectors across multiple levels of partial order time.\",\n \"Title: Room at the Bottom: Authenticated Encryption on Slow Legacy Networks\\nYear: 2011\\n\\nAbstract: The author proposes a streamwise model for online encryption for slow legacy networks.\",\n \"Title: Healthcare information technology's relativity problems: a typology of how patients' physical reality, clinicians' mental models, and healthcare information technology differ.\\nYear: 2014\\n\\nAbstract: Objective To model inconsistencies or distortions among three realities: patients' physical reality; clinicians' mental models of patients' conditions, laboratories, etc; representation of that reality in electronic health records (EHR). To serve as a potential tool for quality improvement of EHRs. Methods Using observations, literature, information technology (IT) logs, vendor and US Food and Drug Administration reports, we constructed scenarios/models of how patients' realities, clinicians' mental models, and EHRs can misalign to produce distortions in comprehension and treatment. We then categorized them according to an emergent typology derived from the cases themselves and refined the categories based on insights gained from the literature of interactive sociotechnical systems analysis, decision support science, and human computer interaction. Typical of grounded theory methods, the categories underwent repeated modifications. Results We constructed 45 scenarios of misalignment between patients' physical realities, clinicians' mental models, and EHRs. We then identified five general types of misrepresentation in these cases: IT data too narrowly focused; IT data too broadly focused; EHRs miss critical reality; data multiplicities-perhaps contradictory or confusing; distortions from data reflected back and forth across users, sensors, and others. The 45 scenarios are presented, organized by the five types. Conclusions With humans, there is a physical reality and actors' mental models of that reality. In healthcare, there is another player: the EHR/healthcare IT, which implicitly and explicitly reflects many mental models, facets of reality, and measures thereof that vary in reliability and consistency. EHRs are both microcosms and shapers of medical care. Our typology and scenarios are intended to be useful to healthcare IT designers and implementers in improving EHR systems and reducing the unintended negative consequences of their use.\",\n \"Title: Blacklistable anonymous credentials: blocking misbehaving users without ttps\\nYear: 2007\\n\\nAbstract: Several credential systems have been proposed in which users can authenticate to services anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a trusted third party (TTP). The ability of the TTP to revoke a user's privacy at any time, however, is too strong a punishment for misbehavior. To limit the scope of deanonymization, systems such as \\\"e-cash\\\" have been proposed in which users are deanonymized under only certain types of well-defined misbehavior such as \\\"double spending.\\\" While useful in some applications, it is not possible to generalize such techniques to more subjective definitions of misbehavior. We present the first anonymous credential system in which services can \\\"blacklist\\\" misbehaving users without contacting a TTP. Since blacklisted users remain anonymous, misbehaviors can be judged subjectively without users fearing arbitrary deanonymization by a TTP.\",\n \"Title: Virtualization and Security: Back to the Future\\nYear: 2008\\n\\nAbstract: The guest editors of the special issue on virtualization introduce the topic space.\",\n \"Title: Using hierarchal change mining to manage network security policy evolution\\nYear: 2011\\n\\nAbstract: Managing the security of complex cloud and networked computing environments requires crafting security policy--ranging from natural-language text to highly-structured configuration rules, sometimes multi-layered--specifying correct system behavior in an adversarial environment. Since environments change and evolve, managing security requires managing evolution of policies, which adds another layer, the change log. However, evolution increases complexity, and the more complex a policy, the harder it is to manage and update, and the more prone it is to be incorrect. This paper proposes hierarchical change mining, drawing upon the tools of software engineering and data mining, to help practitioners introduce fewer errors when they update policy. We discuss our approach and initial findings based on two longitudinal real-world datasets: low-level router configurations from Dartmouth College and high-level Public Key Infrastructure (PKI) certificate policies from the International Grid Trust Federation (IGTF).\",\n \"Title: Securing Information Technology in Healthcare.\\nYear: 2013\\n\\nAbstract: Dartmouth College's Institute for Security, Technology, and Society conducted three workshops on securing information technology in healthcare, attended by a diverse range of experts in the field. This article summarizes the three workshops.\",\n \"Title: Shemp: secure hardware enhanced myproxy\\nYear: 2005\\n\\nAbstract: In 1976, Whitfield Diffie and Martin Hellman demonstrated how public key cryptography could enable secure information exchange between parties that do not share secrets. In order for public key cryptography to work in modern distributed environments, we need an infrastructure for finding and trusting other parties' public keys, i.e., a Public Key Infrastructure (PKI). While PKI applications differ in how they use keys, all applications share one assumption: users have keypairs. This thesis begins by examining the security aspects of some of the standard keystores and their interaction with the Operating System. We establish that desktop keystores are not safe places to store private keys, and our experiments demonstrate the permeability of such keystores. Additionally, desktop keystores are immobile, difficult to use, and make it hard or impossible for relying parties to make reasonable trust judgments. We show that these problems stem from the fact that the Trusted Computing Base (TCB) of modern desktops is too large and ill-defined, which makes standard desktops suboptimal PKI clients. Since we would like to use desktops as PKI clients and cannot realistically expect to redesign the entire desktop, this thesis presents a system that works within the confines of modern desktops to shrink the TCB needed for PKI applications. Our system is called Secure Hardware Enhanced MyProxy (SHEMP), and combines a number of techniques and technologies to shrink the TCB in space and allow the TCB's size to vary over time. In addition, the SHEMP system addresses the problems of immobility and usability, and allows relying parties to make reasonable trust judgments. Using analysis, experiments, and formal methods, we conclude that SHEMP makes standard desktops suitable for use as PKI clients. The contributions of this thesis include the discovery of techniques used to identify weaknesses in modern desktops; a prototype, analysis, and correctness proof of a system which makes desktops usable as PKI clients (SHEMP); a novel approach for reasoning about TCBs; and a formal framework for proving properties of PKI systems such as SHEMP.\",\n \"Title: The diversity of TPMs and its effects on development: a case study of integrating the TPM into OpenSolaris\\nYear: 2010\\n\\nAbstract: Broad adoption of secure programming primitives such as the TPM can be hurt by programmer confusion regarding the nature and representation of failures when using a primitive. Conversely, a clear understanding of the primitive's failure modes is essential for both debugging and reducing the attack surface in the mechanisms built on it. In particular, differences in error processing and reporting logic significantly detract from such understanding. We present a case study of diversity in TPM behaviors and its effects on a TSS implementation, which emerged from the Sun/Dartmouth TCG/OpenSolaris project, one of the goals of which was instrumenting TPM support on Solaris. At the start of the project, both parties believed the instrumentation to be well-defined and, although time-consuming, relatively straightforward. In the course of the project we had to reexamine our assumptions concerning the state of the hardware and the software involved and the view of the system as presented to someone unfamiliar with its internals. We describe some failure modes we encountered and suggest directions for remediation.\",\n \"Title: Using caching for browsing anonymity\\nYear: 2003\\n\\nAbstract: Privacy-providing tools, including tools that provide anonymity, are gaining popularity in the modern world. Among the goals of their users is avoiding tracking and profiling. While some businesses are unhappy with the growth of privacy-enhancing technologies, others can use lack of information about their users to avoid unnecessary liability and even possible harassment by parties with contrary business interests, and to gain a competitive market edge.Currently, users interested in anonymous browsing have the choice only between single-hop proxies and the few more complex systems that are available. These still leave the user vulnerable to long-term intersection attacks.In this paper, we propose a caching proxy system for allowing users to retrieve data from the World-Wide Web in a way that would provide recipient unobservability by a third party and sender unobservability by the recipient and thus dispose with intersection attacks, and report on the prototype we built using Google.\",\n \"Title: TOCTOU, Traps, and Trusted Computing\\nYear: 2008\\n\\nAbstract: The security of the standard TCG architecture depends on whether the values in the platform configuration reg- isters match the actual platform configuration. How- ever, the design of this architecture admits potential for time-of-check time-of-use vulnerabilities: a PCR reflects the value of software and data when it was measured, not when the TPM uses a credential or signs an attes- tation based on that measurement. In this paper, we demonstrate how an attacker with sucient privileges can compromise the integrity of a TPM-protected sys- tem by modifying critical loaded code and static data af- ter measurement has taken place. To solve this problem, we explore using the MMU and the TPM in concert to provide a memory event trapping framework, in which trap handlers perform TPM operations to enforce a se- curity policy. Our framework proposal includes modify- ing the MMU to support selective memory immutability and generate higher granularity memory access traps. To substantiate our ideas, we designed and implemented a software prototype system employing the monitoring capabilities of the Xen virtual machine monitor. We evaluate both the security eectiveness and the perfor- mance overhead of this prototype.\",\n \"Title: Trusted virtual containers on demand\\nYear: 2010\\n\\nAbstract: TPM-based trusted computing aspires to use hardware and cryptography to provide a remote relying party with assurances about the trustworthiness of a computing environment. However, standard approaches to trusted computing are hampered in the areas of scalability, expressiveness, and flexibility. This paper reports on our research project to address these limitations by using TPMs inside OpenSolaris: our kernel creates lightweight containers on demand, and uses DTrace and other tools to extend attestation to more nuanced runtime properties. We illustrate this work with prototype application scenarios from cyber infrastructure operating the U.S. power grid.\",\n \"Title: Yasir: A Low-Latency, High-Integrity Security Retrofit For Legacy Scada Systems\\nYear: 2008\\n\\nAbstract: We construct a bump-in-the-wire (BITW) solution that retrofits security into time-critical communications over bandwidth-limited serial links between devices in legacy Supervisory Control And Data Acquisition (SCADA) systems, on which the proper operations of critical infrastructures such as the electric power grid rely. Previous BITW solutions do not provide the necessary security within timing constraints; the previous solution that does is not BITW. At a hardware cost comparable to existing solutions, our BITW solution provides sufficient security, and yet incurs minimal end-to-end communication latency.\",\n \"Title: A computational framework for certificate policy operations\\nYear: 2009\\n\\nAbstract: The trustworthiness of any Public Key Infrastructure (PKI) rests upon the expectations for trust, and the degree to which those expectations are met. Policies, whether implicit as in PGP and SDSI/SPKI or explicitly required as in X.509, document expectations for trust in a PKI. The widespread use of X.509 in the context of global e-Science infrastructures, financial institutions, and the U.S. Federal government demands efficient, transparent, and reproducible policy decisions. Since current manual processes fall short of these goals, we designed, built, and tested computational tools to process the citation schemes of X.509 certificate policies defined in RFC 2527 and RFC 3647. Our PKI Policy Repository, PolicyBuilder, and PolicyReporter improve the consistency of certificate policy operations as actually practiced in compliance audits, grid accreditation, and policy mapping for bridging PKIs. Anecdotal and experimental evaluation of our tools on real-world tasks establishes their actual utility and suggests how machine-actionable policy might empower individuals to make informed trust decisions in the future.\",\n \"Title: Finding the PKI needles in the Internet haystack\\nYear: 2010\\n\\nAbstract: Public key cryptography can uniquely enable trust within distributed settings. Employing it usually requires deploying a set of tools and services collectively known as a Public Key Infrastructure (PKI). PKIs have become a central asset for many organizations, due to distributed IT and users. Even though the usage of PKIs in closed and controlled environments is quite common, interoperability and usability problems arise when shifting to a broader, open environment. To make an effective trust judgment about a public key certificate, a PKI user needs more than just knowledge of that certificate: she also needs to be able to locate critical parameters such as the certificate repositories and certificate validation servers relevant to that certificate - and all the others the trust path she builds for it. Surprisingly, locating these resources and services remains a largely unsolved problem in real-world X.509 PKI deployment. This issue impacts especially on the usability of this technology and the interoperability of PKIs in open environments such as the Internet. In this paper, we present the design and prototype of a new and flexible solution for automatic discovery of the services and data repositories made available by a Certificate Service Provider (CSP). This contribution will take real-world PKI one step closer to enhancing usability of digital certificates and interoperability between PKIs.\",\n \"Title: TwoKind authentication: usable authenticators for untrustworthy environments\\nYear: 2007\\n\\nAbstract: The ease with which a malicious third party can obtain a user's password when he or she logs into Internet sites (such as bank or email accounts) from an insecure computer creates a substantial security risk to private information and transactions. For example, a malicious administrator at a cybercafe, or a malicious user with sufficient access to install key loggers at a kiosk, can obtain users' passwords easily. Even when users do not trust the machines they are using, many of them are faced with the prospect of accessing their accounts with a single level of privilege. To address this problem, we propose a system based on two modes of authentication--default and restricted. Users can signal to the server whether they are in an untrusted environment so that the server can log them in under restricted privileges that allow them to perform basic actions that cause no serious damage if the session or their password is compromised.\",\n \"Title: Grand Challenges in Information Security: Process and Output\\nYear: 2004\\n\\nAbstract: Even casual observers can see that our society's computing infrastructure has significant security problems. Technical sources such as CERT, BugTraq, and the Risks Digest - not to mention the popular media - regularly catalog critical vulnerabilities in deployed software. Unless we figure out how to build trustworthy systems in the real world, we're in trouble. Recognizing that fact, the Computing Research Association (CRA, www.cra.org), with support from the US National Science Foundation, recently drafted its Grand Research Challenges in security and assurance, intent on galvanizing the field by focusing attention and stimulating progress on these problems.\",\n \"Title: PEREA: towards practical TTP-free revocation in anonymous authentication\\nYear: 2008\\n\\nAbstract: Several anonymous authentication schemes allow servers to revoke a misbehaving user's ability to make future accesses. Traditionally, these schemes have relied on powerful TTPs capable of deanonymizing (or linking) users' connections. Recent schemes such as Blacklistable Anonymous Credentials (BLAC) and Enhanced Privacy ID (EPID) support \\\"privacy-enhanced revocation\\\" -- servers can revoke misbehaving users without a TTP's involvement, and without learning the revoked users' identities. In BLAC and EPID, however, the computation required for authentication at the server is linear in the size (L) of the revocation list. We propose PEREA, a new anonymous authentication scheme for which this bottleneck computation is independent of the size of the revocation list. Instead, the time complexity of authentication is linear in the size (K L) of a revocation window, the number of subsequent authentications before which a user's misbehavior must be recognized if the user is to be revoked. We prove the security of our construction, and have developed a prototype implementation of PEREA to validate its efficiency experimentally.\",\n \"Title: Information Risk in Financial Institutions: Field Study and Research Roadmap\\nYear: 2007\\n\\nAbstract: Large financial firms with thousands of employees face many challenges ensuring workers have access to the right information, yet controlling access to unneeded data. We examine the problems of role lifecycle management and entitlement review processes in the context of large financial institutions. We describe observations from field study research in both retail and investment banks. We examine technologies to enable role and entitlement management and present a roadmap for future research.\",\n \"Title: Never Mind Pearl Harbor--What about a Cyber Love Canal?\\nYear: 2015\\n\\nAbstract: Focusing on malicious attacks on the current infrastructure might be distracting us from another looming challenge: the risk to emerging infrastructure due to carelessness.\",\n \"Title: Intrusion detection for resource-constrained embedded control systems in the power grid.\\nYear: 2012\\n\\nAbstract: The power grid depends on embedded control systems or SCADA systems to function properly. Securing these systems presents unique challenges—in addition to the resource restrictions inherent to embedded devices, SCADA systems must accommodate strict timing requirements that are non-negotiable, and their massive scale greatly amplifies costs such as power consumption. Together, these constraints make the conventional approach to host intrusion detection–using a hypervisor to create a safe environment from which a monitoring entity can operate–too costly or impractical for embedded control systems in the critical infrastructure.\",\n \"Title: Measuring the security impacts of password policies using cognitive behavioral agent-based modeling\\nYear: 2015\\n\\nAbstract: Agent-based modeling can serve as a valuable asset to security personnel who wish to better understand the security landscape within their organization, especially as it relates to user behavior and circumvention. In this paper, we argue in favor of cognitive behavioral agent-based modeling for usable security, report on our work on developing an agent-based model for a password management scenario, perform a sensitivity analysis, which provides us with valuable insights into improving security (e.g., an organization that wishes to suppress one form of circumvention may want to endorse another), and provide directions for future work.\",\n \"Title: Security and Cognitive Bias: Exploring the Role of the Mind\\nYear: 2012\\n\\nAbstract: It's hard to create and configure security technology and hard to use it after deployment. However, the human mind is a component in both security creation and use. While we technologists have spent the last 40 years building fancier machines, psychologists have spent those decades documenting ways in which human minds systematically (and predictably) misperceive things. To what extent might cognitive bias affect the usable security problem?\",\n \"Title: Circumvention of Security: Good Users Do Bad Things\\nYear: 2013\\n\\nAbstract: Conventional wisdom is that the textbook view describes reality, and only bad people (not good people trying to get their jobs done) break the rules. And yet it doesn't, and good people circumvent.\",\n \"Title: Validating an Agent-Based Model of Human Password Behavior.\\nYear: 2016\\n\\nAbstract: Effective reasoning about the impact of security policy decisions requires understanding how human users actually behave, rather than assuming desirable but incorrect behavior. Simulation could help with this reasoning, but it requires building computational models of the relevant human behavior and validating that these models match what humans actually do. In this paper we describe our progress on building agent-based models of human behavior with passwords, and we demonstrate how these models reproduce phenomena shown in the empirical literature.\",\n \"Title: I Am Joe's Fridge: Scalable Identity in the Internet of Things\\nYear: 2016\\n\\nAbstract: Most visions of the emerging Internet of Things (IoT) distribute massive numbers of devices throughout physical infrastructure. In most visions, these devices need to talk to each other. For this to work, the devices need to be able to authenticate each other. Presenting design issues and empirical results, this paper explores the cryptographic infrastructure necessary to capture this identity ontology.\",\n \"Title: Implementing a vertically hardened DNP3 control stack for power applications\\nYear: 2016\\n\\nAbstract: We present an assurance methodology for producing significantly more secure implementations of SCADA/ICS protocols, and describe our case study of applying it to DNP3, in the form of a filtering proxy that deeply and exhaustively validates DNP3 messages. Unlike the vast majority of deployed proprietary DNP3 implementations, our code demonstrates resilience to state-of-the-art black-box as well as white-box fuzz-testing tools.\",\n \"Title: Solving the Grid Defenderźs Dilemma: Tamper Protection for Distributed Cyber-Physical Systems\\nYear: 2015\\n\\nAbstract: Embedded devices installed as part of the smart grid rollout present a major dilemma for grid defenders, because they are soft targets that could allow an attacker to access critical assets (generators, control centers, etc.) deeper in the utilityâs network. While both physical tampering and intrusion protection are large, well-studied fields, state-of-the-art protection schemes suffer from several flaws: They are not powerful enough to respond properly to different tamper events, their severe responses can lead to reduced grid availability, and they often require more setup resources than a utility operator can provide. To protect these networks, we present TEDDI (Tamper Event Detection on Distributed Infrastructure), a distributed, sensor-based tamper protection architecture for embedded devices on utility networks. TEDDI uses data gathered from across the network to make more-informed and more-accurate tamper decisions, and can customize its response based on the event it sees. It can also be configured and installed quickly, without needing a large base of knowledge beforehand. In this paper, we lay out the TEDDI architecture, and discuss how TEDDI solves the grid defenderâs dilemma better than current work.\",\n \"Title: Protecting Against Malicious Bits On the Wire: Automatically Generating a USB Protocol Parser for a Production Kernel.\\nYear: 2017\\n\\nAbstract: Recent efforts to harden hosts against malicious USB devices have focused on the higher layers of the protocol. We present a domain-specific language (DSL) to create a bit-level model of the USB protocol, from which we automatically generate software components that exhaustively validate the bit-level syntax of protocol messages. We use these generated components to create a stateful, connection-tracking firewall for USB. We integrate this firewall with the FreeBSD kernel and demonstrate that it achieves complete mediation of USB traffic, thus protecting the rest of the kernel, including higher-level policy mechanisms such as USBFilter, from low-level attacks via maliciously crafted packets. In addition to in-kernel data structures and packet validation routines, our system generates a user-level policy engine that allows for flexible and expressive firewall behavior beyond mere message syntax validation, as well as functions for pretty-printing packets (which can be used in both the kernel and in protocol analysis software). We use a Haskell back-end to generate C code that we integrate with the FreeBSD kernel, thus making our entire system amenable to formal verification.\",\n \"Title: PhasorSec: Protocol Security Filters for Wide Area Measurement Systems\\nYear: 2018\\n\\nAbstract: The addition of synchrophasors to the power grid to improve observability comes at the cost of an increased attack surface: the wide area measurement system. A common source of zero-days, that can be used to exploit the system, is improper input validation. The strict availability and timing requirements of the grid make it critical that input validation be done right and in a timely fashion. PhasorSec is a hardened security filter for the synchrophasor communication protocol, C37.118. PhasorSec is built using language theoretic principles which treat all input as a language with a specific grammar that defines what input must be accepted. An open-source version of the prototype is provided and evaluation in terms of CPU-time show that it is possible to meet the strict latency requirements. Experiments also demonstrate its effectiveness against the state-of-the-art AFL fuzzer.\",\n \"Title: Going Dark: A Retrospective on the North American Blackout of 2038\\nYear: 2018\\n\\nAbstract: From March 29, 2038, to April 6, 2038, the world observed the North American Blackout of 2038. The blackout left upwards of 300 million people without power, ravaged the world economy, and devastated the global internet. By many accounts, it was the most devastating blackout ever witnessed. That said, its occurrence should not be surprising. While pundits harp on the technical sophistication of the adversary, debate the merits of a kinetic response, and politicize the blackout, the sad reality is that we have, for years, known we were susceptible to such an event. Moreover, we have had the requisite knowledge and tools to avert the blackout, but failed to use them. Plenty has been written on the wide-reaching societal effects of the blackout; our focus will be on the blackout itself.\\n\\nThe Blackout of 2038 had two major phases. In the first phase, an active adversary exploited a vulnerability in the implementation of the Wireless Access in SCADA Environment (WASE) protocol suite that supports the grid. Grid operators acted swiftly and switched to a fallback system to restore power. Unfortunately, the adversary then subverted the fallback system by exploiting a well-known vulnerability in DNP3, a popular industrial control system protocol. The led to the second blackout. Eventually, a patched implementation of the WASE protocol suite was developed and deployed, which restored power.\\n\\nIn hindsight, this blackout stemmed from two erroneous assumptions. First, immediately following the Texas Brownout of 2020, academics, industry professionals, regulators, and other stakeholders advocated for the adoption of a protocol that was formally verified to protect against race conditions (i.e., the cause of the brownout). However, it was wrong to equate formal verification with perfect security; we should have heeded the adage from Donald Knuth, \\\"[b]eware of bugs in the above code; I have only proved it correct, not tried it.\\\" Second, we wrongly assumed a known-to-be-insecure fallback system would be an adequate stopgap until the primary system was back online.\\n\\nThis paper serves as a postmortem to the North American Blackout of 2038. We analyze how the failures came to pass and the assumptions that underlie them. Moreover, we offer a complete and simple solution to prevent these conditions from ever arising again: the adoption of Language-theoretic Security (LangSec) principles. To this end, we provide and evaluate a preliminary implementation of a LangSec parser for the WASE Short Message Protocol format (WSMP). Additionally, we urge lawmakers and regulatory agencies to mandate the verification of fallback protocols.\",\n \"Title: Improving DES coprocessor throughput for short operations\\nYear: 2001\\n\\nAbstract: Over the last several years, our research team built a commercially-offered secure coprocessor that, besides other features, offers high-speed DES: over 20 megabytes/second. However, it obtains these speeds only on operations with large data lengths. For DES operations on short data (e.g., 8-80 bytes), our commercial offering was benchmarked at less than 2 kilobytes/second. The programmability of our device enabled us to investigate this issue, identify and address a series of bottlenecks that were not initially apparent, and ultimately bring our short-DES performance close to 3 megabytes/second. This paper reports the results of this real-world systems exercise in hardware cryptographic acceleration--and demonstrates the importance of, when designing specialty hardware, not overlooking the software aspects governing how a device can be used.\",\n \"Title: Research Report: Parsing PEGs with Length Fields in Software and Hardware\\nYear: 2021\\n\\nAbstract: Since parsers are the line of defense between binaries and untrusted data, they are some of the most common sources of vulnerabilities in software. Language-Theoretic Security provides an approach to implement hardened parsers. We specify the binary format as a formal grammar and implement a recognizer for this formal grammar. However, most binary formats use constructs such as the length field, repeat field, and an offset instruction. Most grammar formats do not support these features. Building on PEGs and calc-regular languages, we propose Calc-Parsing Expression Grammars (Calc-PEGs), a formalization of parsing expression grammars that supports the length field. We design an algorithm to parse Calc-PEGs in $O(n^{2})$ time and a parallel algorithm to parse Calc-PEGs in O(n) time. We also present Pegmatite, a tool to generate these parsers in C, with an option to generate VHDL code.\",\n \"Title: Capturing the iccMAX calculatorElement: A Case Study on Format Design\\nYear: 2022\\n\\nAbstract: ICC profiles are widely used to provide faithful digital color reproduction across a variety of devices, such as monitors, printers, and cameras. In this paper, we document our efforts on reviewing and identifying security issues with the calculatorElement description from the recent iccMAX specification (ICC.2:2019), which expands upon the ICC v4 specification (ICC.1:2010). The iccMAX calculatorElement, which captures a calculator function through a stack-based computational approach, was designed with security in mind. We analyzed the iccMAX calculatorElement using a variety of approaches that utilized: the proof assistant PVS, the theorem-proving language ACL2, the data description language DaeDaLus, and tools tied to the data description language Parsley. Bringing the tools of formal data description, theorem proving, and static analysis to a non-trivial real-world specification has shed light on both the tools and the specification. This exercise has led us to discover numerous bugs within the specification, to identify specification improvements, to identify flaws with a demo implementation, and to recognize ways that we can improve our own tools. Additionally, this particular case study has broader implications for those who work with specification, data description languages, and parsers. In this paper, we document our work on this exercise and relay our key findings.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":82,"string":"82"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":267,"string":"267"}}},{"rowIdx":268,"cells":{"question_id":{"kind":"string","value":"Douglas L Maskell"},"question":{"kind":"string","value":"Generate an abstract for the title \"Are Coarse-Grained Overlays Ready For General Purpose Application Acceleration On Fpgas?\" using the following items: 1. Heterogeneous programmable system\n2. Hardware accelerators\n3. Hybrid FPGAs\n4. FPGA virtualization\n5. Overlay architectures"},"answer":{"kind":"string","value":"Combining processors with hardware accelerators has become a norm with systems-on-chip (SoCs) ever present in modern compute devices. Heterogeneous programmable system on chip platforms sometimes referred to as hybrid FPGAs, tightly couple general purpose processors with high performance reconfigurable fabrics, providing a more flexible alternative. We can now think of a software application with hardware accelerated portions that are reconfigured at runtime. While such ideas have been explored in the past, modern hybrid FPGAs are the first commercial platforms to enable this move to a more software oriented view, where reconfiguration enables hardware resources to be shared by multiple tasks in a bigger application. However, while the rapidly increasing logic density and more capable hard resources found in modern hybrid FPGA devices should make them widely deployable, they remain constrained within specialist application domains. This is due to both design productivity issues and a lack of suitable hardware abstraction to eliminate the need for working with platform-specific details, as server and desktop virtualization has done in a more general sense. To allow mainstream adoption of FPGA based accelerators in general purpose computing, there is a need to virtualize FPGAs and make them more accessible to application developers who are accustomed to software API abstractions and fast development cycles. In this paper, we discuss the role of overlay architectures in enabling general purpose FPGA application acceleration."},"correct_answer":{"kind":"string","value":"Combining processors with hardware accelerators has become a norm with systems-on-chip (SoCs) ever present in modern compute devices. Heterogeneous programmable system on chip platforms sometimes referred to as hybrid FPGAs, tightly couple general purpose processors with high performance reconfigurable fabrics, providing a more flexible alternative. We can now think of a software application with hardware accelerated portions that are reconfigured at runtime. While such ideas have been explored in the past, modern hybrid FPGAs are the first commercial platforms to enable this move to a more software oriented view, where reconfiguration enables hardware resources to be shared by multiple tasks in a bigger application. However, while the rapidly increasing logic density and more capable hard resources found in modern hybrid FPGA devices should make them widely deployable, they remain constrained within specialist application domains. This is due to both design productivity issues and a lack of suitable hardware abstraction to eliminate the need for working with platform-specific details, as server and desktop virtualization has done in a more general sense. To allow mainstream adoption of FPGA based accelerators in general purpose computing, there is a need to virtualize FPGAs and make them more accessible to application developers who are accustomed to software API abstractions and fast development cycles. In this paper, we discuss the role of overlay architectures in enabling general purpose FPGA application acceleration."},"documents":{"kind":"list like","value":["Title: MSA-CUDA: Multiple Sequence Alignment on Graphics Processing Units with CUDA\nYear: 2009\n\nAbstract: Progressive alignment is a widely used approach for computing multiple sequence alignments (MSAs). However, aligning several hundred or thousand sequences with popular progressive alignment tools such as ClustalW requires hours or even days on state-of-the-art workstations. This paper presents MSA-CUDA, a parallel MSA program, which parallelizes all three stages of the ClustalW processing pipeline using CUDA and achieves significant speedups compared to the sequential ClustalW for a variety of large protein sequence datasets. Our tests on a GeForce GTX 280 GPU demonstrate average speedups of 36.91 (for long protein sequences), 18.74 (for average-length protein sequences), and 11.27 (for short protein sequences) compared to the sequential ClustalW running on a Pentium 4 3.0 GHz processor. Our MSA-CUDA outperforms ClustalW-MPI running on 32 cores of a high performance workstation cluster.","Title: A lean FPGA soft processor built using a DSP block\nYear: 2012\n\nAbstract: As Field Programmable Gate Arrays (FPGAs) have advanced, the capabilities and variety of embedded resources have increased. In the last decade, signal processing has become one of the main driving applications for FPGA adoption, so FPGA vendors tailored their architectures to such applications. The resulting embedded digital signal processing (DSP) blocks have now advanced to the point of supporting a wide range of operations. In this paper, we explore how these DSP blocks can be applied to general computation. We show that the DSP48E1 blocks in Xilinx Virtex-6 devices support a wide range of standard processor instructions which can be designed into the core of a basic processor with minimal additional logic usage.","Title: A unified architecture for a public key cryptographic coprocessor\nYear: 2008\n\nAbstract: This paper presents a unified architecture for public key cryptosystems that can support the operations of the Rivest-Shamir-Adleman cryptogram (RSA) and the elliptic curve cryptogram (ECC). A hardware solution is proposed for operations over finite fields GF(p) and GF(2^p). The proposed architecture presents a unified arithmetic unit which provides the functions of dual-field modular multiplication, dual-field modular addition/subtraction, and dual-field modular inversion. A new adder based on the signed-digit (SD) number representation is provided for carry-propagated and carry-less operations. The critical path of the proposed design is reduced compared with previous full adder implementation methods. Experimental results show that the proposed design can achieve a clock speed of 1GHz using 776K gates in a 0.09@mm CMOS standard cell technology, or 150MHz using 5227 CLBs in a Xilinx Virtex 4 FPGA. While the different technologies, platforms and standards make a definitive comparison difficult, based on the performance of our proposed design, we achieve a performance improvement of between 30% and 250% when compared with existing designs.","Title: High level event driven thermal estimation for thermal aware task allocation and scheduling\nYear: 2010\n\nAbstract: Thermal aware scheduling (TAS) is an important system level optimization for CMP and MPSoC. An event driven thermal estimation method which can assist dynamic TAS is proposed in this paper. The event driven thermal estimation is based upon a thermal map which is updated only when a high level event occurs. To minimize the overhead, while maintaining the estimation accuracy, the prebuilt look-up-tables and the superposition principle are used to speed up the solution of the thermal RC network. Experimental results show our method is accurate, producing thermal estimations of similar quality to existing thermal simulators, while having a considerably reduced computational complexity. Our event driven thermal estimation technique is significantly better, in terms of accuracy, than existing TAS schedulers, making it highly suitable for integration into the OS kernel.","Title: CompleteMOTIFs: DNA motif discovery platform for transcription factor binding experiments.\nYear: 2011\n\nAbstract: CompleteMOTIFs (cMOTIFs) is an integrated web tool developed to facilitate systematic discovery of overrepresented transcription factor binding motifs from high-throughput chromatin immunoprecipitation experiments. Comprehensive annotations and Boolean logic operations on multiple peak locations enable users to focus on genomic regions of interest for de novo motif discovery using tools such as MEME, Weeder and ChIPMunk. The pipeline incorporates a scanning tool for known motifs from TRANSFAC and JASPAR databases, and performs an enrichment test using local or precalculated background models that significantly improve the motif scanning result. Furthermore, using the cMOTIFs pipeline, we demonstrated that multiple transcription factors could cooperatively bind to the upstream of important stem cell differentiation regulators.","Title: Estimation of external quantum efficiency for multi-junction solar cells under influence of charged particles using artificial neural networks.\nYear: 2011\n\nAbstract: External quantum efficiency (EQE) of a solar cell is an important parameter as it determines the design efficiency and overall conversion efficiency. The EQE of solar cells for space applications is adversely affected due to bombardment of charged particles in space. Numerical model based softwares, e.g., PC1D, can be used to estimate the EQE under such situation. By varying the cell parameters to fit the measured EQE one can obtain degradation performance of space solar cells. However, due to complex phenomena and interactions occurring between the junctions of the solar cells and the nonlinear influence of charged particles, the accuracy of these models may be limited. In this paper we propose an artificial neural network (ANN)based model to estimate the EQE performance of triple junction InGaP/GaAs/Ge solar cells under the influence of wide range of charged particles. With extensive simulation results we have shown that the ANN-based models provide better estimate of the EQE in terms of mean square error and correlation coefficient than the results reported by Sato et al.","Title: A Novel Fuzzy Associative Memory Architecture for Stock Market Prediction and Trading\nYear: 2011\n\nAbstract: In this paper, a novel stock trading framework based on a neuro-fuzzy associative memory FAM architecture is proposed. The architecture incorporates the approximate analogical reasoning schema AARS to resolve the problem of discontinuous staircase response and inefficient memory utilization with uniform quantization in the associative memory structure. The resultant structure is conceptually clearer and more computationally efficient than the Compositional Rule Inference CRI and Truth Value Restriction TVR fuzzy inference schemes. The local generalization characteristic of the associative memory structure is preserved by the FAM-AARS architecture. The prediction and trading framework exploits the price percentage oscillator PPO for input preprocessing and trading decision making. Numerical experiments conducted on real-life stock data confirm the validity of the design and the performance of the proposed architecture.","Title: A hybrid short read mapping accelerator.\nYear: 2013\n\nAbstract: The rapid growth of short read datasets poses a new challenge to the short read mapping problem in terms of sensitivity and execution speed. Existing methods often use a restrictive error model for computing the alignments to improve speed, whereas more flexible error models are generally too slow for large-scale applications. A number of short read mapping software tools have been proposed. However, designs based on hardware are relatively rare. Field programmable gate arrays (FPGAs) have been successfully used in a number of specific application areas, such as the DSP and communications domains due to their outstanding parallel data processing capabilities, making them a competitive platform to solve problems that are \"inherently parallel\".We present a hybrid system for short read mapping utilizing both FPGA-based hardware and CPU-based software. The computation intensive alignment and the seed generation operations are mapped onto an FPGA. We present a computationally efficient, parallel block-wise alignment structure (Align Core) to approximate the conventional dynamic programming algorithm. The performance is compared to the multi-threaded CPU-based GASSST and BWA software implementations. For single-end alignment, our hybrid system achieves faster processing speed than GASSST (with a similar sensitivity) and BWA (with a higher sensitivity); for pair-end alignment, our design achieves a slightly worse sensitivity than that of BWA but has a higher processing speed.This paper shows that our hybrid system can effectively accelerate the mapping of short reads to a reference genome based on the seed-and-extend approach. The performance comparison to the GASSST and BWA software implementations under different conditions shows that our hybrid design achieves a high degree of sensitivity and requires less overall execution time with only modest FPGA resource utilization. Our hybrid system design also shows that the performance bottleneck for the short read mapping problem can be changed from the alignment stage to the seed generation stage, which provides an additional requirement for the future development of short read aligners.","Title: Towards Run-Time Re-Configurable Techniques for Real-Time Embedded Applications\nYear: 2003\n\nAbstract: Many embedded applications can benefit from the flexible custom computing opportunities that FPGA technology offers. The Run-Time Reconfiguration (RTR) of the FPGA as an application is being served provides futher flexibility. It gives the opportunity to reuse FPGA space used by custom computing circuits that are not operational in a given time frame. Custom computing circuits can meet very light real-time requirements but when it comes to reconfiguring these circuits, the lime taken can be comparatively long and non-deterministic. There is a need for a suitable development environment to investigate how to cope with or reduce the RTR time. This paper describes how this can be achieved with currently available tools and technologies. We first review an appropriate subset of the available technology to implement a system comprising a CPU running a RTOS on a SOPC teal can be adapted using RTR. Then we propose a system architecture that is feasible with current technology. We outline the processes and databases needed to support RTR of the SoPC. We present how the RTOS is made aware of the architectural constraints and reconfiguralion options, thus simplifying the use of reconfigurable hardware for the application programmer.","Title: Unified Signed-Digit Number Adder for RSA and ECC Public-key Cryptosystems\nYear: 2006\n\nAbstract: RSA and ECC are currently the most widely used public key cryptosystems. The computation of RSA and ECC is based on GF(P) and GF(2 p) fields respectively, and composed mainly of addition and XOR operations. An addition operation requires more computation time compared to a XOR operation. This paper proposes a new method to realize a unified architecture for both RSA and ECC public key cryptosystems using a signed-digit (SD) number system so that the carry propagation in the RSA computation can be avoided. Hence, the critical path for the computation of RSA and ECC with the same key length can be shortened compared to other methods using a full adder implementation. Simulation results show that for our proposed architecture the overall speed (the maximum frequency using a key length of 1024 for RSA and a key length of 160 for ECC) can be increased by approximately 28% compared to existing designs with an area of 4355 CLBs when implemented on an FPGA","Title: Biological sequence analysis with hidden markov models on an FPGA\nYear: 2005\n\nAbstract: Molecular biologists use Hidden Markov Models (HMMs) as a popular tool to statistically describe protein families. This statistical description can then be used for sensitive and selective database scanning, e.g. new protein sequences are compared with a set of HMMs to detect functional similarities. Even though efficient dynamic programming algorithms exist for the problem, the required scanning time is still very high, and because of the rapid database growth finding fast solutions is of high importance to research in this area. In this paper we present how reconfigurable architectures can be used to derive an efficient fine-grained parallelization of the dynamic programming calculation. It is described how this technique leads to significant runtime savings for HMM database scanning on a standard off-the-shelf FPGA.","Title: C-based design methodology for FPGA implementation of clustalW MSA\nYear: 2007\n\nAbstract: Systolisation of the pairwise distance computation algorithm and mapping into field programmable gate arrays (FPGA) have proven to give superior performance at a lower cost, compared to the same algorithm running on a cluster of workstations. The primary design methodology for this approach is based on the hardware description languages such as VHDL and Verilog HDL. An alternative design methodology, however, is the use of a high level language such as C to describe the algorithms and generate equivalent hardware descriptions for implementation in FPGA so as to reduce time to market. This paper describes the design and implementation of the ClustalW first stage multiple sequence alignment based on the Smith-Waterman algorithm on a low cost FPGA development platform using a C language development tool suite. Performance evaluation results show that comparable performance could be achieved to that of Pentium 4 systems and other HDL-based solutions using even the smallest commercially available FPGA device with this design methodology.","Title: Dynamic thermal-aware scheduling on chip multiprocessor for soft real-time system\nYear: 2009\n\nAbstract: Thermal aware scheduling (TAS) is an important system level solution for dealing with the thermal issues on CMP. We propose a TAS algorithm based on look up tables to allow the rapid calculation of the post-thermal map from the current thermal profile. We propose two different metrics for determining where to place the task: one based on the maximum core temperature in the post-thermal map; and another based on the sum of the product of the post-thermal map temperature and the remaining task runtime for each core. Experimental results show that our algorithms are better, particularly for high power applications, at minimizing the peak/average temperature, and are able to achieve an average rejection ratio of about 30% to 50% of that chieved by existing algorithms from the literature.","Title: Pre-Routed FPGA Cores for Rapid System Construction in a Dynamic Reconfigurable System\nYear: 2006\n\nAbstract: This paper presents a method of constructing pre-routed FPGA cores which lays the foundations for a rapid system construction framework for dynamically reconfigurable computing systems. There are two major challenges that need to be considered by this framework. The first is how to manage the wires crossing a core's borders. The second is how to maintain an acceptable level of flexibility for system construction with only a minimum of overhead. The perceived advantages of full independent core development are weighed against the loss in placement flexibility and elimination of the opportunities to optimise a system across cores. Few existing methodologies allow the independent compilation of FPGA cores through every step of the design flow. In this paper we analyse the wire detail of modern FPGA architectures to determine how the interconnect architecture effects the shape of pre-routed cores and the wire bandwidth available to interfaces. We have adapted academic placement and routing algorithms to our architectural model. The design flow has been modified to include a wire policy and interface constraints framework that tightly constrains the use of the wires that cross a core's boundaries. Using this tool set we investigate the effect of pre-routing on overall system optimality. A simple example using the pre-routed approach shows only a 2% increase in total wire use over the pre-placed approach. Place and route times are vastly reduced for systems composed of regular modules. Being able to break a system into independent cores reduces the placement and routing time even for non-regular systems.","Title: Multiple Sequence Alignment on an FPGA\nYear: 2005\n\nAbstract: Molecular Biologists frequently compute multiple sequence alignments (MSAs) to identify similar regions in protein families. Progressive alignment is a widely used approach to compute MSAs. However, aligning a few hundred sequences by popular progressive alignment tools requires several hours on sequential computers. Due to the rapid growth of biological sequence databases biologists have to compute MSAs in a far shorter time. In this paper we present a new approach to MSA on reconfigurable hardware platforms to gain high performance at low cost. To derive an efficient mapping onto this type of architecture, fine-grained parallel processing elements (PEs) have been designed. Using this PE design as a building block we have constructed a linear systolic array to perform a pairwise sequence distance computation using dynamic programming. This results in an implementation with significant runtime savings on a standard off-the-shelf FPGA.","Title: DecGPU: distributed error correction on massively parallel graphics processing units using CUDA and MPI.\nYear: 2011\n\nAbstract: Next-generation sequencing technologies have led to the high-throughput production of sequence data (reads) at low cost. However, these reads are significantly shorter and more error-prone than conventional Sanger shotgun reads. This poses a challenge for the de novo assembly in terms of assembly quality and scalability for large-scale short read datasets.We present DecGPU, the first parallel and distributed error correction algorithm for high-throughput short reads (HTSRs) using a hybrid combination of CUDA and MPI parallel programming models. DecGPU provides CPU-based and GPU-based versions, where the CPU-based version employs coarse-grained and fine-grained parallelism using the MPI and OpenMP parallel programming models, and the GPU-based version takes advantage of the CUDA and MPI parallel programming models and employs a hybrid CPU+GPU computing model to maximize the performance by overlapping the CPU and GPU computation. The distributed feature of our algorithm makes it feasible and flexible for the error correction of large-scale HTSR datasets. Using simulated and real datasets, our algorithm demonstrates superior performance, in terms of error correction quality and execution speed, to the existing error correction algorithms. Furthermore, when combined with Velvet and ABySS, the resulting DecGPU-Velvet and DecGPU-ABySS assemblers demonstrate the potential of our algorithm to improve de novo assembly quality for de-Bruijn-graph-based assemblers.DecGPU is publicly available open-source software, written in CUDA C++ and MPI. The experimental results suggest that DecGPU is an effective and feasible error correction algorithm to tackle the flood of short reads produced by next-generation sequencing technologies.","Title: M2E: a multiple-input, multiple-output function extension for RISC-Based extensible processors\nYear: 2006\n\nAbstract: Recent study shows that a further speedup can be achieved by RISC-based extensible processors if the incorporated custom functional units (CFUs) can execute functions with more than two inputs and one output. However, mechanisms to execute multiple-input, multiple-output (MIMO) custom functions in a RISC processor have not been addressed. This paper proposes an extension for single-issue RISC processors based on a CFU that can execute custom functions with up to six inputs and three outputs. To minimize the change to the core processor, we maintain the operand bandwidth of two inputs, one output per cycle and transfer the extra operands and results using repeated custom instructions. While keeping such an limit sacrifices some speedup, our experiments show that the MIMO extension can still achieve an average 51% increase in speedup compared to a dual-input, single-output (DISO) extension and an average 27% increase in speedup compared to a multiple-input, single-output (MISO) extension.","Title: Hyper customized processors for bio-sequence database scanning on FPGAs\nYear: 2005\n\nAbstract: Protein sequences with unknown functionality are often compared to a set of known sequences to detect functional similarities. Efficient dynamic-programming algorithms exist for solving this problem, however current solutions still require significant scan times. These scan time requirements are likely to become even more severe due to exponential database growth. In this paper we present a new approach to bio-sequence database scanning using re-configurable FPGA-based hardware platforms to gain high performance at low cost. Efficient mappings of the Smith-Waterman algorithm using fine-grained parallel processing elements (PEs) that are tailored towards the parameters of a query have been designed. We use customization opportunities available at run-time to dynamically hyper customize the systolic array to make better use of available resource. Our FPGA implementation achieves a speedup of approximately 170 for linear gap penalties and 125 for affine gap penalties as compared to a standard desktop computing platform. We show how hyper-customization at run-time can be used to further improve the performance.","Title: An FPGA Model for Developing Dynamic Circuit Computing\nYear: 2005\n\nAbstract: Computing on SRAM based FPGAs is set to challenge the Instruction Set Architecture (ISA) computing paradigm in the high-performance computing arena. Dynamic Circuit Computing (DCC) techniques increase efficient use of an FPGA. However, the rapid prototyping heritage of the FPGA has resulted in software that is inadequate for exploiting this potential to be a flexible computing platform. A major barrier to the increased use of high performance computing on FPGA is the high computational overhead associated with the management of a DCC system. The ability to explore new approaches in compiler and execution environment design is crucial in order to reduce these overheads. In this paper we report on the development of an open FPGA architecture model and open source compiler tools for the exploration of the complex interaction between the architecture, compiler and execution environment for DCC on FPGA.","Title: A flann-based controller for maximum power point tracking in PV systems under rapidly changing conditions\nYear: 2012\n\nAbstract: In order to increase the efficiency of the Photovoltaic (PV) system, the PV system should be operated at the Maximum Power Point (MPP). The MPP Tracking (MPPT) is an essential part in achieving this improvement. Some of the existing techniques such as Perturb-and-Observe (P&O) and Incremental Conductance (INC) are relatively simpler to implement, but under rapidly changing irradiance and temperature conditions, they fail to track the MPP. Although methods such as Multilayer Perceptron (MLP) and Fuzzy Logic (FL) are efficient in tracking the MPP, their implementation increases the system complexity. In this paper, we propose a novel artificial intelligence based controller for MPPT, which can efficiently track the MPP, while keeping the computational complexity within the limits. Our technique uses Functional Link Artificial Neural Network (FLANN) to predict the PV output voltage at the MPP. Since there is no hidden layer, FLANN is computationally inexpensive. Simulation results verify that the proposed FLANN controller is computationally less intensive and exhibits higher efficiency under rapidly changing weather conditions.","Title: Microkernel hypervisor for a hybrid ARM-FPGA platform\nYear: 2013\n\nAbstract: Reconfigurable architectures have found use in a wide range of application domains, but mostly as static accelerators for computationally intensive functions. Commodity computing adoption has not taken off due primarily to design complexity challenges. Yet reconfigurable architectures offer significant advantages in terms of sharing hardware between distinct isolated tasks, under tight time constraints. Trends towards amalgamation of computing resources in the automotive and aviation domains have so far been limited to non-critical systems, because processor approaches suffer from a lack of predictability and isolation. Hybrid reconfigurable platforms may provide a promising solution to this, by allowing physically isolated access to hardware resources, and support for computationally demanding applications, but with improved programmability and management. We propose virtualized execution and management of software and hardware tasks using a microkernel-based hypervisor running on a commercial hybrid computing platform (the Xilinx Zynq). We demonstrate a framework based on the CODEZERO hypervisor, which has been modified to leverage the capabilities of the FPGA fabric. It supports discrete hardware accelerators, dynamically reconfigurable regions, and regions of virtual fabric, allowing for application isolation and simpler use of hardware resources. A case study demonstrating multiple independent (and isolated) software and hardware tasks is presented.","Title: CUSHAW: a CUDA compatible short read aligner to large genomes based on the Burrows-Wheeler transform.\nYear: 2012\n\nAbstract: Motivation: New high-throughput sequencing technologies have promoted the production of short reads with dramatically low unit cost. The explosive growth of short read datasets poses a challenge to the mapping of short reads to reference genomes, such as the human genome, in terms of alignment quality and execution speed. Results: We present CUSHAW, a parallelized short read aligner based on the compute unified device architecture (CUDA) parallel programming model. We exploit CUDA-compatible graphics hardware as accelerators to achieve fast speed. Our algorithm uses a quality-aware bounded search approach based on the Burrows-Wheeler transform (BWT) and the Ferragina-Manzini index to reduce the search space and achieve high alignment quality. Performance evaluation, using simulated as well as real short read datasets, reveals that our algorithm running on one or two graphics processing units achieves significant speedups in terms of execution time, while yielding comparable or even better alignment quality for paired-end alignments compared with three popular BWT-based aligners: Bowtie, BWA and SOAP2. CUSHAW also delivers competitive performance in terms of single-nucleotide polymorphism calling for an Escherichia coli test dataset.","Title: An improved common subexpression elimination method for reducing logic operators in FIR filter implementations without increasing logic depth\nYear: 2010\n\nAbstract: It is well known that common subexpression elimination techniques minimize the two main cost metrics namely logic operators and logic depths in realizing finite impulse response (FIR) filters. Two classes of common subexpressions occur in the canonic signed digit representation of filter coefficients, called the horizontal and the vertical subexpressions. Previous works have not addressed the trade-offs in using these two types of subexpressions on the logic depth and the number of logic operators of coefficient multipliers. In this paper, we analyze the impact of the horizontal and the vertical common subexpression elimination techniques on reducing the logic depth and number of logic operators in FIR filters. Further, we present an algorithm to optimize the common subexpression elimination that produces FIR filters with fewer numbers of logic operators when compared with other common subexpression elimination algorithms in literature. The design examples show that the average reduction of logic operators achieved using our method over the weight-2 horizontal common subexpression elimination method which produced the best trade-off between logic operators and logic depth (contention resolution algorithm, CRA-2 [F. Xu, C.-H. Chang, C.-C. Jong, Contention resolution algorithm for common subexpression elimination in digital filter design, IEEE Trans. Circuit Syst. II 52(10) (2005) 695-700 (October)]) is 15%. This reduction of logic operators is achieved without any increase in the logic depth. When compared with the recently proposed multiple adder graph (MAG) algorithm [Jeong-Ho Han, In-Cheol Park, FIR filter synthesis considering multiple adder graphs for a coefficient, IEEE Trans. Comput.-Aid. Design Integ. Circuit Syst. 27(5) (2008) 958-962 (May)], the average reduction of logic operators obtained using our method is 5% and the reduction of logic depth is 25%.","Title: High Speed Biological Sequence Analysis With Hidden Markov Models On Reconfigurable Platforms\nYear: 2009\n\nAbstract: Molecular biologists use hidden Markov models (HMMs) as a popular tool to statistically describe biological sequence families. This statistical description can then be used for sensitive and selective database scanning, e. g., new protein sequences are compared with a set of HMMs to detect functional similarities. Efficient dynamic-programming algorithms exist for solving this problem; however, current solutions still require significant scan times. These scan time requirements are likely to become even more severe due to the rapid growth in the size of these databases. This paper shows how reconfigurable architectures can be used to derive an efficient fine-grained parallelization of the dynamic programming calculation. We describe how this technique leads to significant runtime savings for HMM database scanning on a standard off-the-shelf field-programmable gate array (FPGA).","Title: Performance-Power Design Space Exploration in a Hybrid Computing Platform Suitable for Mobile Applications\nYear: 2011\n\nAbstract: Mobile platforms have started to employ FPGA based hardware accelerators to address the ever-increasing demand for computing performance. For many applications, the use of an operating system on the hardware platform proves beneficial for reasons of better resource management and more robust security. This paper evaluates the performance-power implications in a signal processing algorithm with respect to the introduction of Linux OS on two different architectures (a CPU-based and an FPGA-based hybrid architecture). The results reveal that there is a 22 times improvement in energy budget between the CPU-based implementation and the FPGA-based hybrid implementation, with a negligible performance degradation due to the introduction of Linux OS.","Title: Parallel reconstruction of neighbor-joining trees for large multiple sequence alignments using CUDA\nYear: 2009\n\nAbstract: Computing large multiple protein sequence alignments using progressive alignment tools such as ClustalW requires several hours on state-of-the-art workstations. ClustalW uses a three-stage processing pipeline: (i) pairwise distance computation; (ii) phylogenetic tree reconstruction; and (iii) progressive multiple alignment computation. Previous work on accelerating ClustalW was mainly focused on parallelizing the first stage and achieved good speedups for a few hundred input sequences. However, if the input size grows to several thousand sequences, the second stage can dominate the overall runtime. In this paper, we present a new approach to accelerating this second stage using graphics processing units (GPUs). In order to derive an efficient mapping onto the GPU architecture, we present a parallelization of the neighbor-joining tree reconstruction algorithm using CUDA. Our experimental results show speedups of over 26times for large datasets compared to the sequential implementation.","Title: MSAProbs: multiple sequence alignment based on pair hidden Markov models and partition function posterior probabilities.\nYear: 2010\n\nAbstract: Motivation: Multiple sequence alignment is of central importance to bioinformatics and computational biology. Although a large number of algorithms for computing a multiple sequence alignment have been designed, the efficient computation of highly accurate multiple alignments is still a challenge. Results: We present MSAProbs, a new and practical multiple alignment algorithm for protein sequences. The design of MSAProbs is based on a combination of pair hidden Markov models and partition functions to calculate posterior probabilities. Furthermore, two critical bioinformatics techniques, namely weighted probabilistic consistency transformation and weighted profile-profile alignment, are incorporated to improve alignment accuracy. Assessed using the popular benchmarks: BAliBASE, PREFAB, SABmark and OXBENCH, MSAProbs achieves statistically significant accuracy improvements over the existing top performing aligners, including ClustalW, MAFFT, MUSCLE, ProbCons and Probalign. Furthermore, MSAProbs is optimized for multi-core CPUs by employing amulti-threaded design, leading to a competitive execution time compared to other aligners.","Title: C2FPGA-A dependency-timing graph design methodology\nYear: 2013\n\nAbstract: In this paper, we present a design methodology that uses a combined graphical and scheduling technique to map C-based high level language (HLL) based applications to FPGA. Although there are a number of approaches addressing the mapping from HLL to hardware, many of these existing solutions either require a steep learning curve or do not produce an appropriate mapping pattern for the hardware platform. We provide a solution to this problem, by analyzing the data flow and data dependencies in the given code and proposing a scheduling patterns for the given algorithm. We then provide a suitable mapping pattern for the hardware platform. We use the mapping pattern to deliver synthesizable HDL (Verilog) code. We demonstrate our design methodology with results from different real-time case studies that are based on different algorithms.","Title: Automatic Identification of Custom Functions for Embedded Processors with MIMO Extensions\nYear: 2006\n\nAbstract: Commercially available configurable processors nowadays offer opportunities to accelerate embedded applications by implementing customized functions. Previous studies have shown that more speedup can be achieved if these functions are allowed to have more than two inputs and one output. However, automatic identification of multiple-input, multiple-output (MIMO) custom functions is usually slow due to the large exploration space. In this paper, we propose a fast algorithm to enumerate all convex subgraphs that satisfy the input/output constraints from the dataflow graph (DFG) of a basic block. The algorithm can be tuned to determine all subgraphs or only those connected subgraphs. This allows a choice between a better instruction set extension or a faster design space exploration. The algorithm's run time can be orders of magnitude better than previous algorithms when a custom function is allowed to have two or more outputs","Title: CUDA-MEME: Accelerating motif discovery in biological sequences using CUDA-enabled graphics processing units\nYear: 2010\n\nAbstract: Motif discovery in biological sequences is of prime importance and a major challenge in computational biology. Consequently, numerous motif discovery tools have been developed to date. However, the rapid growth of both genomic sequence and gene transcription data, establishes the need for the development of scalable motif discovery tools. An approach to improve the runtime of motif discovery by an order-of-magnitude without losing sensitivity is to employ emerging many-core architectures such as CUDA-enabled GPUs. In this paper, we present a highly parallel formulation and implementation of the MEME motif discovery algorithm using the CUDA programming model. To achieve high efficiency, we introduce two parallelization approaches: sequence-level and substring-level parallelization. Furthermore, a hybrid computing framework is described to take advantage of both CPU and GPU compute resources. Our performance evaluation on a GeForce GTX 280 GPU, results in average runtime speedups of 21.4 (19.3) for the starting point search and 20.5 (16.4) for the overall runtime using the OOPS (ZOOPS) motif search model. The runtime speedups of CUDA-MEME on a single GPU are also comparable to those of ParaMEME running on 16 CPU cores of a high-performance workstation cluster. In addition to the fast speed, CUDA-MEME has the capability of finding motif instances consistent with the sequential MEME.","Title: A technique for expressing IT security objectives\nYear: 2006\n\nAbstract: At the specification phase, the developer of an IT security product identifies and documents applicable security objectives. Specifications are often intuitive and hard to assess and while being syntactically correct may still fail to appropriately capture the security problem addressed. A technique is proposed for expressing Common Criteria compliant security environments and security objectives for high assurance IT security products. The technique is validated by an analysis of the security specification for a device computing digital signatures within the European Union PKI framework. Modifications to the specification are proposed and the possibility of extending the CC treatment of security objectives is discussed.","Title: EpiList II: Closing the Loop in the Development of Generic Cognitive Skills\nYear: 2010\n\nAbstract: The importance of cognitive skills in human learning and reasoning has become well established in recent years. This motivates the search for a knowledge representation that supports the development of a computational algorithm that performs, as well as instructs such cognitive skills. Cognitive skills can be broadly divided into two types: specific and generic cognitive skills. Intelligent tutoring systems (ITSs) that develop generic cognitive skills are essential for developing classification, generalization, and comparison processes. However, these current systems are inherently open loop and do not utilize feedback, based on the student's competence level, to adapt the learning process. This is a major drawback when attempting to provide a dynamic learner-focused approach for effective instruction. In this paper, we present EpiList II, an ITS that closes the loop and is hence able to monitor and dynamically assess the student's cognitive-skill competence. The results show a significant improvement in positive- and negative-reasoning skills, with 51% of students (up from an average of 8% of students when using an open-loop ITS) acquiring/developing these skills.","Title: Fourth Workshop On Using Emerging Parallel Architectures\nYear: 2012\n\nAbstract: The Fourth Workshop on Using Emerging Parallel Architectures (WEPA), held in conjunction with ICCS 2012, provides a forum for exploring the capabilities of emerging parallel architectures such as GPUs, FPGAs, Cell B. E., Intel M. I. C. and multi-cores to accelerate computational science applications.","Title: A Brain Inspired Fuzzy Neuro-Predictor For Bank Failure Analysis\nYear: 2006\n\nAbstract: Bank failure prediction is important to bank regulators, including central banks and financial ministries. Off-site surveillance systems or early warning models use financial statements or other rating systems to assess the financial status of the banks. Statistical based bank failure prediction models assume a normal probability distribution and equal dispersion on the data that is often violated. Neural network (NN) based models do not make these assumptions about the data. NNs give better prediction results, however, they lack explanatory capabilities. Fuzzy-neural networks (FNN), allow explanatory capabilities and give better performance. In this paper, several bank failure prediction models using the pseudo outer product-based FNN with a compositional rule of inference and singleton fuzzifier (POPFNN-CRI(S)) are proposed. The system uses financial covariates derived from publicly available financial statements to predict failing banks. The performances of the models are assessed through the classification of 3636 US banks for one-year and two-year periods. As it is not possible to obtain all financial statements, we also propose a model to aid in the reconstruction of missing financial data using POPFNN-CRI(S). To complete the study, the effect that missing data has on the outcome of bank failure prediction is examined.","Title: Using reconfigurable hardware to accelerate multiple sequence alignment with ClustalW\nYear: 2005\n\nAbstract: Summary: Aligning hundreds of sequences using progressive alignment tools such as ClustalW requires several hours on state-of-the-art workstations. We present a new approach to compute multiple sequence alignments in far shorter time using reconfigurable hardware. This results in an implementation of ClustalW with significant runtime savings on a standard off-the-shelf FPGA. Availability: An online server for ClustalW running on a Pentium IV 3 GHz with a Xilinx XC2V6000 FPGA PCI-board is available at http://beta.projectproteus.org. The PE hardware design in Verilog HDL is available on request from the first author. Contact: tim.oliver@pmail.ntu.edu.sg","Title: High-speed Multiple Sequence Alignment on a reconfigurable platform\nYear: 2006\n\nAbstract: Progressive alignment is a widely used approach to compute multiple sequence alignments (MSAs). However, aligning several hundred sequences by popular progressive alignment tools requires hours on sequential computers. Due to the rapid growth of sequence databases biologists have to compute MSAs in a far shorter time. In this paper we present a new approach to MSA on reconfigurable hardware platforms to gain high performance at low cost. We have constructed a linear systolic array to perform pairwise sequence distance computations using dynamic programming. This results in an implementation with significant runtime savings on a standard FPGA.","Title: iDEA: A DSP block based FPGA soft processor\nYear: 2012\n\nAbstract: This paper presents a very lean DSP Extension Architecture (iDEA) soft processor for Field Programmable Gate Arrays (FPGAs). iDEA has been built to be as lightweight as possible, utilising the run-time flexibility of the DSP48E1 primitive in Xilinx FPGAs to serve as many processor functions as possible. We show how the primitive's flexibility can be leveraged within a general-purpose processor, what additional circuitry is needed, and present a full instruction-set architecture. The result is a very compact processor that can run at high speed, while executing a full gamut of general machine instructions. We provide results for a number of simple applications, and show how the processor's resource requirements and frequency compare to a Xilinx MicroBlaze soft core. Based on the DSP48E1, this processor can be deployed across next-generation Xilinx Artix-7, Kintex-7, and Virtex-7 families.","Title: An Ultrafast Scalable Many-Core Motif Discovery Algorithm for Multiple GPUs\nYear: 2011\n\nAbstract: The identification of genome-wide transcription factor binding sites is a fundamental and crucial problem to fully understand the transcriptional regulatory processes. However, the high computational cost of many motif discovery algorithms heavily constraints their application for large-scale datasets. The rapid growth of genomic sequences and gene transcription data further deteriorates the situation and establishes a strong requirement for time-efficient scalable motif discovery algorithms. The emergence of many-core architectures, typically CUDA-enabled GPUs, provides an opportunity to reduce the execution time by an order of magnitude without the loss of accuracy. In this paper, we present mCUDA-MEME, an ultrafast scalable many-core motif discovery algorithm for multiple GPUs based on the MEME algorithm. Our algorithm is implemented using a hybrid combination of the CUDA, OpenMP and MPI parallel programming models in order to harness the powerful compute capability of modern GPU clusters. At present, our algorithm supports OOPS and ZOOPS models, which are sufficient for most motif discovery applications. mCUDAMEME achieves significant speedups for the starting point search stage (and the overall execution) when benchmarked, using real datasets, against parallel MEME running on 32 CPU cores. Speedups of up to 1.4 (1.1) on a single GPU of a Fermi-based Tesla S2050 quad-GPU computing system and up to 10.8 (8.3) on the eight GPUs of a two Tesla S2050 system were observed. Furthermore, our algorithm shows good scalability with respect to dataset size and the number of GPUs (availability:https://sites.google.com/site/yongchaosoftware/mc uda-meme).","Title: Parallelized short read assembly of large genomes using de Bruijn graphs.\nYear: 2011\n\nAbstract: Next-generation sequencing technologies have given rise to the explosive increase in DNA sequencing throughput, and have promoted the recent development of de novo short read assemblers. However, existing assemblers require high execution times and a large amount of compute resources to assemble large genomes from quantities of short reads.We present PASHA, a parallelized short read assembler using de Bruijn graphs, which takes advantage of hybrid computing architectures consisting of both shared-memory multi-core CPUs and distributed-memory compute clusters to gain efficiency and scalability. Evaluation using three small-scale real paired-end datasets shows that PASHA is able to produce more contiguous high-quality assemblies in shorter time compared to three leading assemblers: Velvet, ABySS and SOAPdenovo. PASHA's scalability for large genome datasets is demonstrated with human genome assembly. Compared to ABySS, PASHA achieves competitive assembly quality with faster execution speed on the same compute resources, yielding an NG50 contig size of 503 with the longest correct contig size of 18,252, and an NG50 scaffold size of 2,294. Moreover, the human assembly is completed in about 21 hours with only modest compute resources.Developing parallel assemblers for large genomes has been garnering significant research efforts due to the explosive size growth of high-throughput short read datasets. By employing hybrid parallelism consisting of multi-threading on multi-core CPUs and message passing on compute clusters, PASHA is able to assemble the human genome with high quality and in reasonable time using modest compute resources.","Title: Supporting multiple-input, multiple-output custom functions in configurable processors\nYear: 2007\n\nAbstract: Configurable processors have emerged as a promising solution for high performance embedded systems. Many of these processors extend a RISC core with configurable functional units that execute dual-input, single-output (DISO) custom functions. Although studies have shown that supporting multiple-input, multiple-output (MIMO) custom functions can lead to significant speedups, mechanisms to efficiently achieve this have not been adequately addressed. The underlying reason is that a custom function is normally invoked by a single instruction, which usually transfers only two inputs and one output. Attempts to transfer more inputs and outputs in one instruction are impeded by the instruction length and the register file's R/W ports. This paper proposes a simple extension to transfer multiple inputs and outputs of the custom functions using repeated instructions. While transferring the inputs and outputs may take a few extra cycles, our experiments show that the MIMO extension can still achieve an average 51% increase in speedup compared to a DISO extension and an average 27% increase in speedup compared to a multiple-input, single-output (MISO) extension.","Title: A dependency graph based methodology for parallelizing HLL applications on FPGA (abstract only)\nYear: 2010\n\nAbstract: Reconfigurable computing is an exciting new area of research. It opens up a number of new computing paradigms with the potential to significantly change the embedded computing landscape. Unfortunately, as with any new concept, there is much to be done before it can be brought into the mainstream. Reconfigurable computing needs to be made more usable by the general computing community by making the application mapping process more user transparent. We need to be able to efficiently exploit the parallelism and high communications bandwidth available in reconfigurable computing systems, such as provided by FPGA devices. In this paper we propose a framework to map C-based applications to an FPGA based system. The framework relies on dependency based analysis information obtained from a high level Intermediate Representation (IR) of the C-Application. The dependencies have a major impact on the instruction flow and the parallelism of the algorithms when implemented on FPGA based high performance computing platforms. We demonstrate the importance of these dependencies in algorithms by examining a compute intensive bio-informatics application. Targeting on a Xilinx Virtex 5 XC5VFX70T FPGA, our place and route results achieved 92% of the clock frequency achieved by using a manual design of the same application. The contribution in this paper is to provide a semi-automated approach to generate hardware for FPGA based systems through a high level data dependency graphical IR.","Title: A Fast High-Level Event-Driven Thermal Estimator for Dynamic Thermal Aware Scheduling\nYear: 2012\n\nAbstract: Thermal aware scheduling (TAS) is an important system level optimization for many-core systems. A fast event driven thermal estimation method, which includes both the dynamic and leakage power models, for monitoring temperature and guiding dynamic TAS (DTAS) is proposed in this paper. The fast event driven thermal estimation is based upon a thermal map, with occasional thermal sensor-based calibration, which is updated only when a high level event occurs. To minimize the overhead, while maintaining the estimation accuracy, prebuilt look-up-tables and predefined leakage calibration parameters are used to speed up the thermal solution. Experimental results show our method is accurate, producing thermal estimations of similar quality to an existing open-source thermal simulator, while having a considerably reduced computational complexity. Based on this predictive approach, we take full advantage of a projected future thermal map to develop several heuristic policies for DTAS. We show that our proposed predictive policies are significantly better, in terms of minimizing average/peak temperature, reducing the dynamic thermal management overhead and improving other real-time features, than existing DTAS schedulers, making them highly suitable for heuristically guiding thermal aware task allocation and scheduling.","Title: Accelerating the viterbi algorithm for profile hidden markov models using reconfigurable hardware\nYear: 2006\n\nAbstract: Profile Hidden Markov Models (PHMMs) are used as a popular tool in bioinformatics for probabilistic sequence database searching. The search operation consists of computing the Viterbi score for each sequence in the database with respect to a given query PHMM. Because of the rapid growth of biological sequence databases, finding fast solutions is of highest importance to research in this area. Unfortunately, the required scan times of currently available sequential software implementations are very high. In this paper we show how reconfigurable hardware can be used as a computational platform to accelerate this application by two orders of magnitude.","Title: Fcmac-Aars: A Novel Fnn Architecture For Stock Market Prediction And Trading\nYear: 2006\n\nAbstract: A novel fuzzy neural network architecture, the approximate analogical reasoning based fuzzy CMAC (FCMAC-AARS), is proposed. AARS is incorporated into the fuzzy CMAC structure as it is conceptually clearer and more computationally efficient than the CRI and TVR fuzzy inference schemes. A prediction and trading framework has been proposed which exploits the price percentage oscillator (PPO) for input preprocessing and trading decision making. Numerical experiments conducted on real-life stock data confirm the validity of the design and the performance of the FCMAC-AARS system.","Title: A Reconfigurable Bloom Filter Architecture for BLASTN\nYear: 2009\n\nAbstract: Efficient seed-based filtration methods exist for scanning genomic sequence databases. However, current solutions require a significant scan time on traditional computer architectures. These scan time requirements are likely to become even more severe due to the rapid growth in the size of databases. In this paper, we present a new approach to genomic sequence database scanning using reconfigurable field-programmable gate array (FPGA)-based hardware. To derive an efficient mapping onto this type of architecture, we propose a reconfigurable Bloom filter architecture. Our experimental results show that the FPGA implementation achieves an order of magnitude speedup compared to the NCBI BLASTN software running on a general purpose computer.","Title: Prerouted FPGA cores for rapid system construction in a dynamic reconfigurable system\nYear: 2007\n\nAbstract: A method of constructing prerouted FPGA cores, which lays the foundations for a rapid system construction framework for dynamically reconfigurable computing systems, is presented. Two major challenges are considered: how tomanage the wires crossing a core's borders; and how to maintain an acceptable level of flexibility for system construction with only a minimum of overhead. In order to maintain FPGA computing performance, it is crucial to thoroughly analyze the issues at the lowest level of device detail in order to ensure that computing circuit encapsulation is as efficient as possible. We present the first methodology that allows a core to scale its interface bandwidth to the maximum available in a routing channel. Cores can be constructed independently from the rest of the system using a framework that is independent of the method used to place and route primitive components within the core. We use an abstract FPGA model and CAD tools that mirror those used in industry. An academic design flow has been modified to include a wire policy and an interface constraints framework that tightly constrains the use of the wires that cross a core's boundaries. Using this tool set we investigate the effect of prerouting on overall system optimality. Abutting cores are instantly connected by colocation of interface wires. Eliminating run-time routing drastically reduces the time taken to construct a system using a set of cores.","Title: The iDEA DSP Block-Based Soft Processor for FPGAs\nYear: 2014\n\nAbstract: DSP blocks in modern FPGAs can be used for a wide range of arithmetic functions, offering increased performance while saving logic resources for other uses. They have evolved to better support a plethora of signal processing tasks, meaning that in other application domains they may be underutilised. The DSP48E1 primitives in new Xilinx devices support dynamic programmability that can help extend their usefulness; the specific function of a DSP block can be modified on a cycle-by-cycle basis. However, the standard synthesis flow does not leverage this flexibility in the vast majority of cases. The lean DSP Extension Architecture (iDEA) presented in this article builds around the dynamic programmability of a single DSP48E1 primitive, with minimal additional logic to create a general-purpose processor supporting a full instruction-set architecture. The result is a very compact, fast processor that can execute a full gamut of general machine instructions. We show a number of simple applications compiled using an MIPS compiler and translated to the iDEA instruction set, comparing with a Xilinx MicroBlaze to show estimated performance figures. Being based on the DSP48E1, this processor can be deployed across next-generation Xilinx Artix-7, Kintex-7, Virtex-7, and Zynq families.","Title: An Improved Robust Field-Weakeaning Algorithm for Direct-Torque-Controlled Synchronous-Reluctance-Motor Drives\nYear: 2015\n\nAbstract: This paper presents an improved field weakening (FW) algorithm for synchronous-reluctance-motor drives. The proposed algorithm is robust to the variations in the machine d- and q-axis inductances. The transition between the maximum torque per ampere, current and voltage limits, and the maximum torque per flux trajectories is smooth. The proposed technique is combined with the direct-torque-control method to attain a high performance drive in the FW region. Simulation and experimental results are supplemented to verify the effectiveness of the proposed approach.","Title: Virtualized Execution and Management of Hardware Tasks on a Hybrid ARM-FPGA Platform\nYear: 2014\n\nAbstract: Emerging hybrid reconfigurable platforms tightly couple capable processors with high performance reconfigurable fabrics. This promises to move the focus of reconfigurable computing systems from static accelerators to a more software oriented view, where reconfiguration is a key enabler for exploiting the available resources. This requires a revised look at how to manage the execution of such hardware tasks within a processor-based system, and in doing so, how to virtualize the resources to ensure isolation and predictability. This view is further supported by trends towards amalgamation of computation in the automotive and avionics domains, where such properties are essential to overall system reliability. We present the virtualized execution and management of software and hardware tasks using a microkernel-based hypervisor running on a commercial hybrid computing platform (the Xilinx Zynq). The CODEZERO hypervisor has been modified to leverage the capabilities of the FPGA fabric, with support for discrete hardware accelerators, dynamically reconfigurable regions, and regions of virtual fabric. We characterise the communication overheads in such a hybrid system to motivate the importance of lean management, before quantifying the context switch overhead of the hypervisor approach. We then compare the resulting idle time for a standard Linux implementation and the proposed hypervisor method, showing two orders of magnitude improved performance with the hypervisor.","Title: A uniform implementation scheme for evolutionary optimization algorithms and the experimental implementation of an ACO based MPPT for PV systems under partial shading\nYear: 2014\n\nAbstract: Partial shading is one of the important issues in maximum power point (MPP) tracking (MPPT) for photovoltaic (PV) systems. Multiple peaks on the power-voltage (P-V) curve under partial shading conditions can result in a conventional MPPT technique failing to track the global MPP, thus causing large power losses. Whereas, evolutionary optimization algorithms exhibit many advantages when applying them to MPPT, such as, the ability to track the global MPP, no requirement for irradiance or temperature sensors, system independence without knowledge of the PV system in advance, reduced current/voltage sensors compared to conventional methods when applied to PV systems with a distributed MPPT structure. This paper presents a uniform scheme for implementing evolutionary algorithms into the MPPT under various PV array structures. The effectiveness of the proposed method is verified both by simulations and experimental setup. The implementation of the ant colony optimization (ACO) based MPPT is conducted using this uniform scheme. In addition, a strategy to accelerate the convergence speed, which is important in systems with partial shading caused by rapid irradiance change, is also discussed.","Title: A hardware efficient implementation of an adaptive subsample delay estimator\nYear: 2004\n\nAbstract: A real-time algorithm for estimating the subsample delay between two noisy sinusoidal signals is presented. The new technique is based on the recently proposed discrete-time quadrature delay estimator (QDE). The algorithm uses all of the in-phase and quadrature-phase components of the received signals to produce a bias-free estimate of the delay between the input signals. The technique directly updates the delay error estimate, which is in turn used to adapt the coefficients of a simple fractional delay filter (FDF). The algorithm is insensitive to variations in the amplitudes of the input signals, and does not require an accurate estimate of the frequency of the input sinusoids. The technique is simple to implement and has a significantly reduced complexity compared to other adaptive techniques. Simulations show that in the presence of system noise, the new estimator outperforms conventional fractional delay filter based estimators.","Title: The design of multiplierless FIR filters with a minimum adder step and reduced hardware complexity\nYear: 2006\n\nAbstract: We propose an algorithm for reducing the hardware complexity of linear phase FIR digital filters without resorting to an increase in the number of adder steps in the multiplier block adders. We aggressively reduce both the coefficient wordlength and the number of non-zero bits in the filter coefficients so that the adder step can be minimized. The hardware implementation of the coefficients is such that the number of full adders is proportional to the product of the input signal wordlength and the number of adders. That is, in general, the number of full adders is independent of the coefficient wordlength and the number of shifts between nonzero bits in the coefficient. Results show that the proposed technique achieves a 67% and 71% reduction in the number of multiplier block adders and the number of multiplier block full adders respectively. Our technique has been successfully applied to filters with up to 500 taps","Title: Software-Oriented Approach to Hardware-Software Co-Simulation for FPGA-Based Risc Extensible Processor\nYear: 2006\n\nAbstract: Recent advancements in mixed hardware-software modeling platforms have simplified the process of concurrently modeling complex algorithms in hardware while considering the software generation in an integrated environment. To efficiently facilitate design space exploration for RISC extensible processors, it is imperative to use a tightly coupled hardware-software co-design and modeling effort that also maintains the flexibility for exploring other types of microarchitectures. We have introduced a simulation framework using a software-oriented design methodology that can be adopted to model the software and hardware components in a reconfigurable co-processor. Experiments on some commonly used DSP and image processing tasks show that hardware-software trade-offs in the various models can be efficiently analyzed during the initial design phase.","Title: Execution Objects for Dynamically Reconfigurable FPGA Systems\nYear: 2006\n\nAbstract: This paper explores the use of pre-routed cores as execution objects in an object-oriented programming model and execution environment for dynamic computing on FPGA. In order to maintain FPGA computing performance it is crucial to thoroughly analyze the issues at the lowest level of device detail in order to ensure that computing circuit encapsulation is as efficient as possible. The first methodology that allows a core to scale its interface bandwidth to the maximum available in a routing channel was presented. Cores can be constructed independently from the rest of the system using a framework that is independent of the method used to place and route primitive components within the core. The authors used an architecture model and CAD tools that mirror those used in industry. Abutting cores are instantly connected by co-location of interface wires. Eliminating run-time routing drastically reduces the time taken to construct a system using a set of cores. It was illustrated how, although pre-routing has an adverse impact on core performance by up to 14%, it can improve functional density by up to six times for rapid reconfiguration","Title: Type-2 GA-TSK fuzzy neural network\nYear: 2007\n\nAbstract: A novel fuzzy-neural network, the type-2 GA- TSKfnn (T2GA-TSKfnn), combining a type-2 fuzzy logic system (FLS) and a genetic algorithm (GA) based Takagi-Sugeno- Kang fuzzy neural network (GA-TSKfnn), is presented. The rational for this combination is that type-2 fuzzy sets are better able to deal with rule uncertainties, while the optimal GA-based tuning of the T2GA-TSKfnn parameters achieves better classification results. However, a general T2GA-TSKfnn is computationally very intensive due to the complexity of the type-2 to type-1 reduction. Therefore, we adopt an interval T2GA-TSKfnn implementation to simplify the computational process. Simulation results are provided to compare the T2GA-TSKfnn against other fuzzy neural networks. These results show that the proposed system is able to achieve a higher classification rate when compared against a number of other traditional neuro-fuzzy classifiers.","Title: Efficient multiplierless channel filters for multi-standard SDR\nYear: 2008\n\nAbstract: This paper investigates the design of very low complexity multiplierless linear phase FIR filters for use in the channelizer of multi-standard software defined radios. A technique for reducing the hardware complexity of linear phase FIR digital filters which minimizes the adder depth and the number of adders in the multiplier block is introduced and is used to implement a multistage, multi-standard decimating filter. The design reuses components for different communications standards and is thus ideal for use in systems which support dynamic reconfiguration.","Title: Reconfigurable Accelerator for the Word-Matching Stage of BLASTN\nYear: 2013\n\nAbstract: BLAST is one of the most popular sequence analysis tools used by molecular biologists. It is designed to efficiently find similar regions between two sequences that have biological significance. However, because the size of genomic databases is growing rapidly, the computation time of BLAST, when performing a complete genomic database search, is continuously increasing. Thus, there is a clear need to accelerate this process. In this paper, we present a new approach for genomic sequence database scanning utilizing reconfigurable field programmable gate array (FPGA)-based hardware. In order to derive an efficient structure for BLASTN, we propose a reconfigurable architecture to accelerate the computation of the word-matching stage. The experimental results show that the FPGA implementation achieves a speedup around one order of magnitude compared to the NCBI BLASTN software running on a general purpose computer.","Title: Current-controlled resonant circuit based photovoltaic micro-inverter with half- wave cycloconverter\nYear: 2013\n\nAbstract: An electronically-controlled series resonant circuit based micro-inverter with a full-bridge inverter and a half-wave cycloconverter is proposed for single phase distributed photovoltaic (PV) systems rated up to 400W. A series resonant circuit and a high frequency transformer are used to couple the full-bridge inverter and the half-wave cycloconverter. Inductor of the series resonant circuit is used to control output current of the micro-inverter. The proposed current control strategy of the micro-inverter is mathematically analyzed. The proposed micro-inverter is simulated using the MATLAB/PLECS block set in order to verify feasibility of the proposed current control method in series resonant circuit based DC-AC converters. Experimental results are obtained to further validate the proposed current control method.","Title: A distributed minority and majority voting based redundancy scheme\nYear: 2015\n\nAbstract: This article presents a new distributed minority-cum-majority voting based redundancy (DMMR) scheme that is scalable and has the ability to tolerate multiple function module faults/failures. In comparison with 5-tuple, 7-tuple, and 9-tuple versions of the N-modular redundancy scheme, the proposed DMMR scheme whilst being equally fault-tolerant reports respective improvements in design metrics (i.e., figure-of-merit) by 32.5%, 180.4% and 377.4% for example ASIC-based implementations utilizing a 4×4 array multiplier as the representative function module, whilst reporting very small corresponding decreases in system reliability by just 1.21%, 1.06% and 1.08% for consideration of module reliabilities ranging from 0.9 to 0.99. The simulation results are obtained using a 32/28nm CMOS process.","Title: A racetrack memory based in-memory booth multiplier for cryptography application\nYear: 2016\n\nAbstract: Security is an important concern in cloud computing nowadays. RSA is one of the most popular asymmetric encryption algorithms that are widely used in internet based applications for its public key strategy advantage over symmetric encryption algorithms. However, RSA encryption algorithm is very compute intensive, which would affect the speed and power efficiency of the encountered applications. Racetrack Memory (RM) is a newly introduced promising technology in future storage and memory system, which is perfect to be used in memory intensive scenarios because of its high data density. However, novel designs should be applied to exploit the advantages of RM while avoiding the adverse impact of its sequential access mechanism. In this paper, we present an in-memory Booth multiplier based on racetrack memory to alleviate this problem. As the building block of our multiplier, a racetrack memory based adder is proposed, which saves 56.3% power compared with the state-of-the-art magnetic adder. Integrated with the storage element, our proposed multiplier shows great efficiency in area, power and scalability.","Title: Efficient Overlay Architecture Based on DSP Blocks\nYear: 2015\n\nAbstract: Design productivity and long compilation times are major issues preventing the mainstream adoption of FPGAs in general purpose computing. Several overlay architectures have emerged to tackle these challenges, but at the cost of increased area and performance overheads. This paper examines a coarse grained overlay architecture designed using the flexible DSP48E1 primitive on Xilinx FPGAs. This allows pipelined execution at significantly higher throughput without adding significant area overheads to the PE. We map several benchmarks, using our custom mapping tool, and show that the proposed overlay architecture delivers a throughput of up to 21.6 GOPS and provides an 11 -- 52% improvement in throughput compared to Vivado HLS implementations.","Title: Automatic Fault Detection And Diagnosis For Photovoltaic Systems Using Combined Artificial Neural Network And Analytical Based Methods\nYear: 2015\n\nAbstract: Long term exposure of photovoltaic (PV) systems under relatively harsh and changing environmental conditions can result in fault conditions developing during the operational lifetime. The present solution is for system operators to manually perform condition monitoring of the PV system. However, it is time-consuming, inaccurate and dangerous. Thus, automatic fault detection and diagnosis is a critical task to ensure the reliability and safety in PV systems. The current state-of-the-art techniques either cannot provide enough detailed fault information with high accuracy or have too much complexity. This work presents an automatic fault detection and diagnosis method for string based PV systems. It combines an artificial neural network (ANN) with the conventional analytical method to conduct the fault detection and diagnosis tasks. A two-layered ANN is applied to predict the expected power which is then compared with the measured power from the real PV system. Based on the difference between the ANN estimated power and the measured power, the open circuit voltage and short circuit current of the PV string determined using analytical equations are used to identify any of the six defined fault types. The proposed method has a fast detection, compact structure and good accuracy. Simulation results show the effective fault detection and diagnosis capability of the proposed method.","Title: Adapting the DySER Architecture with DSP Blocks as an Overlay for the Xilinx Zynq.\nYear: 2015\n\nAbstract: Coarse-grained overlay architectures have been shown to be effective when paired with general purpose processors, offering software-like programmability, fast compilation, and improved design productivity. These architectures enable general purpose hardware accelerators, allowing hardware design at a higher level of abstraction, but at the cost of area and performance overheads. This paper examines the DySER overlay architecture as a hardware accelerator paired with a general purpose processor in a hybrid FPGA such as the Xilinx Zynq. We evaluate the DySER architecture mapped on the Xilinx Zynq and show that it suffers from a significant area and performance overhead. We then propose an improved functional unit architecture using the flexibility of the DSP48E1 primitive which results in a 2.5 times frequency improvement and 25% area reduction compared to the original functional unit architecture. We demonstrate that this improvement results in the routing architecture becoming the bottleneck in performance.","Title: An Area-Efficient FPGA Overlay using DSP Block based Time-multiplexed Functional Units.\nYear: 2016\n\nAbstract: Coarse grained overlay architectures improve FPGA design productivity by providing fast compilation and software-like programmability. Throughput oriented spatially configurable overlays typically suffer from area overheads due to the requirement of one functional unit for each compute kernel operation. Hence, these overlays have often been of limited size, supporting only relatively small compute kernels while consuming considerable FPGA resources. This paper examines the possibility of sharing the functional units among kernel operations for reducing area overheads. We propose a linear interconnected array of time-multiplexed FUs as an overlay architecture with reduced instruction storage and interconnect resource requirements, which uses a fully-pipelined, architecture-aware FU design supporting a fast context switching time. The results presented show a reduction of up to 85% in FPGA resource requirements compared to existing throughput oriented overlay architectures, with an operating frequency which approaches the theoretical limit for the FPGA device.","Title: DeCO: A DSP Block Based FPGA Accelerator Overlay with Low Overhead Interconnect\nYear: 2016\n\nAbstract: Coarse-grained FPGA overlay architectures paired with general purpose processors offer a number of advantages for general purpose hardware acceleration because of software-like programmability, fast compilation, application portability, and improved design productivity. However, the area overheads of these overlays, and in particular architectures with island-style interconnect, negate many of these advantages, preventing their use in practical FPGA-based systems. Crucially, the interconnect flexibility provided by these overlay architectures is normally over-provisioned for accelerators based on feed-forward pipelined datapaths, which in many cases have the general shape of inverted cones. We propose DeCO, a cone shaped cluster of FUs utilizing a simple linear interconnect between them. This reduces the area overheads for implementing compute kernels extracted from compute-intensive applications represented as directed acyclic dataflow graphs, while still allowing high data throughput. We perform design space exploration by modeling programmability overhead as a function of overlay design parameters, and compare to the programmability overhead of island-style overlays. We observe 87% savings in LUT requirements using the proposed approach compared to DSP block based island-style overlays. Our experimental evaluation shows that the proposed overlay exhibits an achievable frequency of 395 MHz, close to the DSP theoretical limit on the Xilinx Zynq. We also present an automated tool flow that provides a rapid and vendor-independent mapping of the high level compute kernel code to the proposed overlay.","Title: Throughput Oriented Fpga Overlays Using Dsp Blocks\nYear: 2016\n\nAbstract: Design productivity is a major concern preventing the mainstream adoption of FPGAs. Overlay architectures have emerged as one possible solution to this challenge, offering fast compilation and software-like programmability. However, overlays typically suffer from area and performance overheads due to limited consideration for the underlying FPGA architecture. These overlays have often been of limited size, supporting only relatively small compute kernels. This paper examines the possibility of developing larger, more efficient, overlays using multiple DSP blocks and then maximising utilisation by mapping multiple instances of kernels simultaneously onto the overlay to exploit kernel level parallelism. We show a significant improvement in achievable overlay size and overlay utilisation, with a reduction of almost 70% in the overlay tile requirement compared to existing overlay architectures, an operating frequency in excess of 300 MHz, and kernel throughputs of almost 60 GOPS.","Title: Resource-Aware Just-in-Time OpenCL Compiler for Coarse-Grained FPGA Overlays.\nYear: 2017\n\nAbstract: FPGA vendors have recently started focusing on OpenCL for FPGAs because of its ability to leverage the parallelism inherent to heterogeneous computing platforms. OpenCL allows programs running on a host computer to launch accelerator kernels which can be compiled at run-time for a specific architecture, thus enabling portability. However, the prohibitive compilation times (specifically the FPGA place and route times) are a major stumbling block when using OpenCL tools from FPGA vendors. The long compilation times mean that the tools cannot effectively use just-in-time (JIT) compilation or runtime performance scaling. Coarse-grained overlays represent a possible solution by virtue of their coarse granularity and fast compilation. In this paper, we present a methodology for run-time compilation of OpenCL kernels to a DSP block based coarse-grained overlay, rather than directly to the fine-grained FPGA fabric. The proposed methodology allows JIT compilation and on-demand resource-aware kernel replication to better utilize available overlay resources, raising the abstraction level while reducing compile times significantly. We further demonstrate that this approach can even be used for run-time compilation of OpenCL kernels on the ARM processor of the embedded heterogeneous Zynq device.","Title: Approximate ripple carry and carry lookahead adders — A comparative analysis\nYear: 2017\n\nAbstract: Approximate ripple carry adders (RCAs) and carry lookahead adders (CLAs) are presented which are compared with accurate RCAs and CLAs for performing a 32-bit addition. The accurate and approximate RCAs and CLAs are implemented using a 32/28nm CMOS process. Approximations ranging from 4- to 20-bits are considered for the less significant adder bit positions. The simulation results show that approximate RCAs report reductions in the power-delay product (PDP) ranging from 19.5% to 82% than the accurate RCA for approximation sizes varying from 4- to 20-bits. Also, approximate CLAs report reductions in PDP ranging from 16.7% to 74.2% than the accurate CLA for approximation sizes varying from 4- to 20-bits. On average, for the approximation sizes considered, it is observed that approximate CLAs achieve a 46.5% reduction in PDP compared to the approximate RCAs. Hence, approximate CLAs are preferable over approximate RCAs for the low power implementation of approximate computer arithmetic.","Title: Asynchronous early output section-carry based carry lookahead adder with alias carry logic\nYear: 2017\n\nAbstract: A new asynchronous early output section-carry based carry lookahead adder (SCBCLA) with alias carry output logic is presented in this paper. To evaluate the proposed SCBCLA with alias carry logic and to make a comparison with other CLAs, a 32-bit addition operation is considered. Compared to the weak-indication SCBCLA with alias logic, the proposed early output SCBCLA with alias logic reports a 13% reduction in area without any increases in latency and power dissipation. On the other hand, in comparison with the early output recursive CLA (RCLA), the proposed early output SCBCLA with alias logic reports a 16% reduction in latency while occupying almost the same area and dissipating almost the same average power. All the asynchronous CLAs are quasi-delay-insensitive designs which incorporate the delay-insensitive dual-rail data encoding and adhere to the 4-phase return-to-zero handshaking. The adders were realized and the simulations were performed based on a 32/28nm CMOS process.","Title: A novel two-stage modular multiplier based on racetrack memory for asymmetric cryptography\nYear: 2017\n\nAbstract: Asymmetric cryptography algorithms such as RSA are widely used in applications such as blockchain technology and cloud computing to ensure the security and privacy of data. However, the encryption and decryption operations of asymmetric cryptography algorithms involve many computation-intensive multiplications, which require high memory bandwidth and involve large performance and resource overhead. Emerging non-volatile memory technologies such as racetrack memory are regarded to be promising for all levels of memory hierarchy to reduce the area and power overhead due to their high data density and nearly zero leakage. In this paper, we propose an efficient racetrack memory based in-memory design to accelerate the modular multiplication for asymmetric cryptography algorithms. A novel two-stage scalable modular multiplication algorithm is proposed to significantly improve the delay. An efficient architecture is further developed to reduce the number of required adders by half. Experimental results show that our proposed scheme improves the energy efficiency by 45.9%, the area efficiency by 93.6% and achieves 8x of throughput per area compared with the state-of-the-art CMOS-based implementation.","Title: A Time-Multiplexed Fpga Overlay With Linear Interconnect\nYear: 2018\n\nAbstract: Coarse-grained overlays improve FPGA design productivity by providing fast compilation and software like programmability. Soft processor based overlays with well-defined ISAs are attractive to application developers due to their ease of use. However, these overlays have significant FPGA resource overheads. Time multiplexed (TM) CGRA-like overlays represent an interesting alternative as they are able to change their behavior on a cycle by cycle basis while the compute kernel executes. This reduces the FPGA resource needed, but at the cost of a higher initiation interval (II) and hence reduced throughput.The fully flexible routing network of current CGRA-like overlays results in high FPGA resource usage. However, many application kernels are acyclic and can be implemented using a much simpler linear feed-forward routing network. This paper examines a DSP block based TM overlay with linear interconnect where the overlay architecture takes account of the application kernels' characteristics and the underlying FPGA architecture, so as to minimize the II and the FPGA resource usage. We examine a number of architectural extensions to the DSP block based functional unit to improve the II, throughput and latency. The results show an average 70% reduction in II, with corresponding improvements in throughput and latency.","Title: A Self-Healing Redundancy Scheme for Mission/Safety-Critical Applications.\nYear: 2018\n\nAbstract: In the nanoelectronics era, multiple faults or failures in circuits and systems deployed in mission- and safety-critical applications, such as space, aerospace, nuclear etc., are known to occur. To withstand these, higher order redundancy is suggested to be used selectively in the sensitive portions of a circuit or system. In this context, the distributed minority and majority voting based redundancy (DMMR) scheme was proposed as an alternative to the N-modular redundancy (NMR) scheme for the efficient implementation of higher order redundancy. However, the DMMR scheme is not self-healing. In this paper, we present a new self-healing redundancy (SHR) scheme that can inherently correct its internal faults or fail- ures without any external intervention, which makes it ideal for mission/safety-critical applications. To achieve the same degree of fault tolerance, the SHR scheme requires fewer function blocks than the NMR and DMMR schemes. We present the architectures of the proposed SHR scheme, discuss the system reliability, and provide the design metrics estimated for example SHR systems alongside the corresponding NMR and DMMR systems using a 32/28-nm CMOS technology. From the perspectives of fault tolerance, self-healing capability, and optimizations in the design metrics, the SHR scheme is preferable to the NMR and DMMR schemes.","Title: A Hybrid Logic Block Architecture in FPGA for Holistic Efficiency.\nYear: 2017\n\nAbstract: This brief presents a hybrid design of a configurable logic block (CLB) composed of look-up tables (LUTs) and universal logic gates (ULGs). A ULG is designed to realize holistic efficiency compared with the corresponding LUT. Previous designs with ULGs are either based on pure ULG or LUT-ULG complementary architecture, which incur a longer delay or double the area compared to the LUT-based design....","Title: Approximate quasi-delay-insensitive asynchronous adders: Design and analysis\nYear: 2017\n\nAbstract: Approximate computing is gaining increasing interest among the VLSI design community due to its potential for enabling low power, high speed, and less area while delivering acceptably correct computation results for many digital signal processing applications. In this context, this paper considers for the first time asynchronous quasi-delay-insensitive (QDI) realizations of approximate adders which are compared with some existing accurate asynchronous QDI adders based on a 32/28nm CMOS technology. The simulation results and analysis show that approximate asynchronous computing is preferable over accurate asynchronous computing when the accuracy may be traded-off to achieve optimizations in the design metrics.","Title: Generalized Majority Voter Design Method For N-Modular Redundant Systems Used In Mission- And Safety-Critical Applications\nYear: 2019\n\nAbstract: Mission- and safety-critical circuits and systems employ redundancy in their designs to overcome any faults or failures of constituent circuits and systems during the normal operation. In this aspect, the N-modular redundancy (NMR) is widely used. An NMR system is comprised of N identical systems, the corresponding outputs of which are majority voted to generate the system outputs. To perform majority voting, a majority voter is required, and the sizes of majority voters tend to vary depending on an NMR system. Majority voters corresponding to NMR systems are physically realized by enumerating the majority input clauses corresponding to an NMR system and then synthesizing the majority logic equation. The issue is that the number of majority input clauses corresponding to an NMR system is governed by a mathematical combination, the complexity of which increases substantially with increases in the level of redundancy. In this context, the design of a majority voter of any size corresponding to an NMR specification based on a new, generalized design approach is described. The proposed approach is inherently hierarchical and progressive since any NMR majority voter can be constructed from an (N - 2)MR majority voter along with additional logic corresponding to the two extra inputs. Further, the proposed approach paves the way for simultaneous production of the NMR system outputs corresponding to different degrees of redundancy, which is not intrinsic to the existing methods. This feature is additionally useful for any sharing of common logic with diverse degrees of redundancy in appropriate portions of an NMR implementation.","Title: Asynchronous Early Output Block Carry Lookahead Adder with Improved Quality of Results.\nYear: 2019\n\nAbstract: A new asynchronous early output, relative-timed block carry lookahead adder (BCLA) incorporating redundant carries is proposed. Compared to the best of existing semi-custom asynchronous carry lookahead adders (CLAs) employing delay-insensitive data encoding and following a 4-phase handshaking, the proposed BCLA with redundant carries achieves 14.9% reduction in cycle time and 12.3% reduction in area with no power penalty. A hybrid variant involving a ripple carry adder (RCA) in the least significant stages i.e. BCLA-RCA is also considered that achieves 15.2% reduction in cycle time and 11.2% reduction in area over the best of existing hybrid CLARCA variants without power penalty.","Title: Majority and Minority Voted Redundancy for Safety-Critical Applications.\nYear: 2019\n\nAbstract: A new majority and minority voted redundancy (MMR) scheme is proposed that can provide the same degree of fault tolerance as N-modular redundancy (NMR) but with fewer function units and a less sophisticated voting logic. Example NMR and MMR circuits were implemented using a 32/28nm CMOS process and compared. The results show that MMR circuits dissipate less power, occupy less area, and encounter less critical path delay than the corresponding NMR circuits while providing the same degree of fault tolerance. Hence the MMR is a promising alternative to the NMR to efficiently implement high levels of redundancy in safety-critical applications.","Title: Coarse Grained FPGA Overlay for Rapid Just-In-Time Accelerator Compilation\nYear: 2022\n\nAbstract: Coarse-grained FPGA overlays built around the runtime programmable DSP blocks in modern FPGAs can achieve high throughput and improved scalability compared to traditional overlays built without detailed consideration of FPGA architecture. These overlays can be mapped to using higher level compilers, achieving fast compilation, software-like programmability and run-time management, and high-level d...","Title: Approximator: A Software Tool for Automatic Generation of Approximate Arithmetic Circuits\nYear: 2022\n\nAbstract: Approximate arithmetic circuits are an attractive alternative to accurate arithmetic circuits because they have significantly reduced delay, area, and power, albeit at the cost of some loss in accuracy. By keeping errors due to approximate computation within acceptable limits, approximate arithmetic circuits can be used for various practical applications such as digital signal processing, digital filtering, low power graphics processing, neuromorphic computing, hardware realization of neural networks for artificial intelligence and machine learning etc. The degree of approximation that can be incorporated into an approximate arithmetic circuit tends to vary depending on the error resiliency of the target application. Given this, the manual coding of approximate arithmetic circuits corresponding to different degrees of approximation in a hardware description language (HDL) may be a cumbersome and a time-consuming process-more so when the circuit is big. Therefore, a software tool that can automatically generate approximate arithmetic circuits of any size corresponding to a desired accuracy would not only aid the design flow but also help to improve a designer's productivity by speeding up the circuit/system development. In this context, this paper presents 'Approximator', which is a software tool developed to automatically generate approximate arithmetic circuits based on a user's specification. Approximator can automatically generate Verilog HDL codes of approximate adders and multipliers of any size based on the novel approximate arithmetic circuit architectures proposed by us. The Verilog HDL codes output by Approximator can be used for synthesis in an FPGA or ASIC (standard cell based) design environment. Additionally, the tool can perform error and accuracy analyses of approximate arithmetic circuits. The salient features of the tool are illustrated through some example screenshots captured during different stages of the tool use. Approximator has been made open-access on GitHub for the benefit of the research community, and the tool documentation is provided for the user's reference.","Title: An Approximate Adder with Reduced Error and Optimized Design Metrics\nYear: 2021\n\nAbstract: We present a new approximate adder with reduced error and optimized design metrics. The proposed approximate adder is derived by modifying an existing approximate adder HERLOA and is called modified HERLOA or M-HERLOA in short. We considered a systematic modification of HERLOA to derive an optimum M-HERLOA for a digital image processing application. We calculated popular error parameters such as mean absolute error (also called mean error distance) and root mean square error of the approximate adders. We estimated the design metrics of accurate and approximate adders based on FPGA and ASIC (standard cell based) implementations. We compare the performance of accurate adder and approximate adders for an image processing application by estimating the peak signal to noise ratio and structural similarity index metric. We find that the proposed M-HERLOA reconstructs a digital image that is similar to the image reconstructed using the accurate adder. This is achieved with M-HERLOA simultaneously enabling following optimizations in design metrics compared to the accurate adder for a 32 bit addition: (i) 9.5% reduction in minimum clock period, 9.1% reduction in total on-chip power consumption, and 7 LUTs and 18 flip-flops less for a FPGA implementation, and (ii) 18% reduction in critical path delay, 26.7% reduction in average power dissipation, and 23.1% reduction in silicon area for an ASIC type implementation."],"string":"[\n \"Title: MSA-CUDA: Multiple Sequence Alignment on Graphics Processing Units with CUDA\\nYear: 2009\\n\\nAbstract: Progressive alignment is a widely used approach for computing multiple sequence alignments (MSAs). However, aligning several hundred or thousand sequences with popular progressive alignment tools such as ClustalW requires hours or even days on state-of-the-art workstations. This paper presents MSA-CUDA, a parallel MSA program, which parallelizes all three stages of the ClustalW processing pipeline using CUDA and achieves significant speedups compared to the sequential ClustalW for a variety of large protein sequence datasets. Our tests on a GeForce GTX 280 GPU demonstrate average speedups of 36.91 (for long protein sequences), 18.74 (for average-length protein sequences), and 11.27 (for short protein sequences) compared to the sequential ClustalW running on a Pentium 4 3.0 GHz processor. Our MSA-CUDA outperforms ClustalW-MPI running on 32 cores of a high performance workstation cluster.\",\n \"Title: A lean FPGA soft processor built using a DSP block\\nYear: 2012\\n\\nAbstract: As Field Programmable Gate Arrays (FPGAs) have advanced, the capabilities and variety of embedded resources have increased. In the last decade, signal processing has become one of the main driving applications for FPGA adoption, so FPGA vendors tailored their architectures to such applications. The resulting embedded digital signal processing (DSP) blocks have now advanced to the point of supporting a wide range of operations. In this paper, we explore how these DSP blocks can be applied to general computation. We show that the DSP48E1 blocks in Xilinx Virtex-6 devices support a wide range of standard processor instructions which can be designed into the core of a basic processor with minimal additional logic usage.\",\n \"Title: A unified architecture for a public key cryptographic coprocessor\\nYear: 2008\\n\\nAbstract: This paper presents a unified architecture for public key cryptosystems that can support the operations of the Rivest-Shamir-Adleman cryptogram (RSA) and the elliptic curve cryptogram (ECC). A hardware solution is proposed for operations over finite fields GF(p) and GF(2^p). The proposed architecture presents a unified arithmetic unit which provides the functions of dual-field modular multiplication, dual-field modular addition/subtraction, and dual-field modular inversion. A new adder based on the signed-digit (SD) number representation is provided for carry-propagated and carry-less operations. The critical path of the proposed design is reduced compared with previous full adder implementation methods. Experimental results show that the proposed design can achieve a clock speed of 1GHz using 776K gates in a 0.09@mm CMOS standard cell technology, or 150MHz using 5227 CLBs in a Xilinx Virtex 4 FPGA. While the different technologies, platforms and standards make a definitive comparison difficult, based on the performance of our proposed design, we achieve a performance improvement of between 30% and 250% when compared with existing designs.\",\n \"Title: High level event driven thermal estimation for thermal aware task allocation and scheduling\\nYear: 2010\\n\\nAbstract: Thermal aware scheduling (TAS) is an important system level optimization for CMP and MPSoC. An event driven thermal estimation method which can assist dynamic TAS is proposed in this paper. The event driven thermal estimation is based upon a thermal map which is updated only when a high level event occurs. To minimize the overhead, while maintaining the estimation accuracy, the prebuilt look-up-tables and the superposition principle are used to speed up the solution of the thermal RC network. Experimental results show our method is accurate, producing thermal estimations of similar quality to existing thermal simulators, while having a considerably reduced computational complexity. Our event driven thermal estimation technique is significantly better, in terms of accuracy, than existing TAS schedulers, making it highly suitable for integration into the OS kernel.\",\n \"Title: CompleteMOTIFs: DNA motif discovery platform for transcription factor binding experiments.\\nYear: 2011\\n\\nAbstract: CompleteMOTIFs (cMOTIFs) is an integrated web tool developed to facilitate systematic discovery of overrepresented transcription factor binding motifs from high-throughput chromatin immunoprecipitation experiments. Comprehensive annotations and Boolean logic operations on multiple peak locations enable users to focus on genomic regions of interest for de novo motif discovery using tools such as MEME, Weeder and ChIPMunk. The pipeline incorporates a scanning tool for known motifs from TRANSFAC and JASPAR databases, and performs an enrichment test using local or precalculated background models that significantly improve the motif scanning result. Furthermore, using the cMOTIFs pipeline, we demonstrated that multiple transcription factors could cooperatively bind to the upstream of important stem cell differentiation regulators.\",\n \"Title: Estimation of external quantum efficiency for multi-junction solar cells under influence of charged particles using artificial neural networks.\\nYear: 2011\\n\\nAbstract: External quantum efficiency (EQE) of a solar cell is an important parameter as it determines the design efficiency and overall conversion efficiency. The EQE of solar cells for space applications is adversely affected due to bombardment of charged particles in space. Numerical model based softwares, e.g., PC1D, can be used to estimate the EQE under such situation. By varying the cell parameters to fit the measured EQE one can obtain degradation performance of space solar cells. However, due to complex phenomena and interactions occurring between the junctions of the solar cells and the nonlinear influence of charged particles, the accuracy of these models may be limited. In this paper we propose an artificial neural network (ANN)based model to estimate the EQE performance of triple junction InGaP/GaAs/Ge solar cells under the influence of wide range of charged particles. With extensive simulation results we have shown that the ANN-based models provide better estimate of the EQE in terms of mean square error and correlation coefficient than the results reported by Sato et al.\",\n \"Title: A Novel Fuzzy Associative Memory Architecture for Stock Market Prediction and Trading\\nYear: 2011\\n\\nAbstract: In this paper, a novel stock trading framework based on a neuro-fuzzy associative memory FAM architecture is proposed. The architecture incorporates the approximate analogical reasoning schema AARS to resolve the problem of discontinuous staircase response and inefficient memory utilization with uniform quantization in the associative memory structure. The resultant structure is conceptually clearer and more computationally efficient than the Compositional Rule Inference CRI and Truth Value Restriction TVR fuzzy inference schemes. The local generalization characteristic of the associative memory structure is preserved by the FAM-AARS architecture. The prediction and trading framework exploits the price percentage oscillator PPO for input preprocessing and trading decision making. Numerical experiments conducted on real-life stock data confirm the validity of the design and the performance of the proposed architecture.\",\n \"Title: A hybrid short read mapping accelerator.\\nYear: 2013\\n\\nAbstract: The rapid growth of short read datasets poses a new challenge to the short read mapping problem in terms of sensitivity and execution speed. Existing methods often use a restrictive error model for computing the alignments to improve speed, whereas more flexible error models are generally too slow for large-scale applications. A number of short read mapping software tools have been proposed. However, designs based on hardware are relatively rare. Field programmable gate arrays (FPGAs) have been successfully used in a number of specific application areas, such as the DSP and communications domains due to their outstanding parallel data processing capabilities, making them a competitive platform to solve problems that are \\\"inherently parallel\\\".We present a hybrid system for short read mapping utilizing both FPGA-based hardware and CPU-based software. The computation intensive alignment and the seed generation operations are mapped onto an FPGA. We present a computationally efficient, parallel block-wise alignment structure (Align Core) to approximate the conventional dynamic programming algorithm. The performance is compared to the multi-threaded CPU-based GASSST and BWA software implementations. For single-end alignment, our hybrid system achieves faster processing speed than GASSST (with a similar sensitivity) and BWA (with a higher sensitivity); for pair-end alignment, our design achieves a slightly worse sensitivity than that of BWA but has a higher processing speed.This paper shows that our hybrid system can effectively accelerate the mapping of short reads to a reference genome based on the seed-and-extend approach. The performance comparison to the GASSST and BWA software implementations under different conditions shows that our hybrid design achieves a high degree of sensitivity and requires less overall execution time with only modest FPGA resource utilization. Our hybrid system design also shows that the performance bottleneck for the short read mapping problem can be changed from the alignment stage to the seed generation stage, which provides an additional requirement for the future development of short read aligners.\",\n \"Title: Towards Run-Time Re-Configurable Techniques for Real-Time Embedded Applications\\nYear: 2003\\n\\nAbstract: Many embedded applications can benefit from the flexible custom computing opportunities that FPGA technology offers. The Run-Time Reconfiguration (RTR) of the FPGA as an application is being served provides futher flexibility. It gives the opportunity to reuse FPGA space used by custom computing circuits that are not operational in a given time frame. Custom computing circuits can meet very light real-time requirements but when it comes to reconfiguring these circuits, the lime taken can be comparatively long and non-deterministic. There is a need for a suitable development environment to investigate how to cope with or reduce the RTR time. This paper describes how this can be achieved with currently available tools and technologies. We first review an appropriate subset of the available technology to implement a system comprising a CPU running a RTOS on a SOPC teal can be adapted using RTR. Then we propose a system architecture that is feasible with current technology. We outline the processes and databases needed to support RTR of the SoPC. We present how the RTOS is made aware of the architectural constraints and reconfiguralion options, thus simplifying the use of reconfigurable hardware for the application programmer.\",\n \"Title: Unified Signed-Digit Number Adder for RSA and ECC Public-key Cryptosystems\\nYear: 2006\\n\\nAbstract: RSA and ECC are currently the most widely used public key cryptosystems. The computation of RSA and ECC is based on GF(P) and GF(2 p) fields respectively, and composed mainly of addition and XOR operations. An addition operation requires more computation time compared to a XOR operation. This paper proposes a new method to realize a unified architecture for both RSA and ECC public key cryptosystems using a signed-digit (SD) number system so that the carry propagation in the RSA computation can be avoided. Hence, the critical path for the computation of RSA and ECC with the same key length can be shortened compared to other methods using a full adder implementation. Simulation results show that for our proposed architecture the overall speed (the maximum frequency using a key length of 1024 for RSA and a key length of 160 for ECC) can be increased by approximately 28% compared to existing designs with an area of 4355 CLBs when implemented on an FPGA\",\n \"Title: Biological sequence analysis with hidden markov models on an FPGA\\nYear: 2005\\n\\nAbstract: Molecular biologists use Hidden Markov Models (HMMs) as a popular tool to statistically describe protein families. This statistical description can then be used for sensitive and selective database scanning, e.g. new protein sequences are compared with a set of HMMs to detect functional similarities. Even though efficient dynamic programming algorithms exist for the problem, the required scanning time is still very high, and because of the rapid database growth finding fast solutions is of high importance to research in this area. In this paper we present how reconfigurable architectures can be used to derive an efficient fine-grained parallelization of the dynamic programming calculation. It is described how this technique leads to significant runtime savings for HMM database scanning on a standard off-the-shelf FPGA.\",\n \"Title: C-based design methodology for FPGA implementation of clustalW MSA\\nYear: 2007\\n\\nAbstract: Systolisation of the pairwise distance computation algorithm and mapping into field programmable gate arrays (FPGA) have proven to give superior performance at a lower cost, compared to the same algorithm running on a cluster of workstations. The primary design methodology for this approach is based on the hardware description languages such as VHDL and Verilog HDL. An alternative design methodology, however, is the use of a high level language such as C to describe the algorithms and generate equivalent hardware descriptions for implementation in FPGA so as to reduce time to market. This paper describes the design and implementation of the ClustalW first stage multiple sequence alignment based on the Smith-Waterman algorithm on a low cost FPGA development platform using a C language development tool suite. Performance evaluation results show that comparable performance could be achieved to that of Pentium 4 systems and other HDL-based solutions using even the smallest commercially available FPGA device with this design methodology.\",\n \"Title: Dynamic thermal-aware scheduling on chip multiprocessor for soft real-time system\\nYear: 2009\\n\\nAbstract: Thermal aware scheduling (TAS) is an important system level solution for dealing with the thermal issues on CMP. We propose a TAS algorithm based on look up tables to allow the rapid calculation of the post-thermal map from the current thermal profile. We propose two different metrics for determining where to place the task: one based on the maximum core temperature in the post-thermal map; and another based on the sum of the product of the post-thermal map temperature and the remaining task runtime for each core. Experimental results show that our algorithms are better, particularly for high power applications, at minimizing the peak/average temperature, and are able to achieve an average rejection ratio of about 30% to 50% of that chieved by existing algorithms from the literature.\",\n \"Title: Pre-Routed FPGA Cores for Rapid System Construction in a Dynamic Reconfigurable System\\nYear: 2006\\n\\nAbstract: This paper presents a method of constructing pre-routed FPGA cores which lays the foundations for a rapid system construction framework for dynamically reconfigurable computing systems. There are two major challenges that need to be considered by this framework. The first is how to manage the wires crossing a core's borders. The second is how to maintain an acceptable level of flexibility for system construction with only a minimum of overhead. The perceived advantages of full independent core development are weighed against the loss in placement flexibility and elimination of the opportunities to optimise a system across cores. Few existing methodologies allow the independent compilation of FPGA cores through every step of the design flow. In this paper we analyse the wire detail of modern FPGA architectures to determine how the interconnect architecture effects the shape of pre-routed cores and the wire bandwidth available to interfaces. We have adapted academic placement and routing algorithms to our architectural model. The design flow has been modified to include a wire policy and interface constraints framework that tightly constrains the use of the wires that cross a core's boundaries. Using this tool set we investigate the effect of pre-routing on overall system optimality. A simple example using the pre-routed approach shows only a 2% increase in total wire use over the pre-placed approach. Place and route times are vastly reduced for systems composed of regular modules. Being able to break a system into independent cores reduces the placement and routing time even for non-regular systems.\",\n \"Title: Multiple Sequence Alignment on an FPGA\\nYear: 2005\\n\\nAbstract: Molecular Biologists frequently compute multiple sequence alignments (MSAs) to identify similar regions in protein families. Progressive alignment is a widely used approach to compute MSAs. However, aligning a few hundred sequences by popular progressive alignment tools requires several hours on sequential computers. Due to the rapid growth of biological sequence databases biologists have to compute MSAs in a far shorter time. In this paper we present a new approach to MSA on reconfigurable hardware platforms to gain high performance at low cost. To derive an efficient mapping onto this type of architecture, fine-grained parallel processing elements (PEs) have been designed. Using this PE design as a building block we have constructed a linear systolic array to perform a pairwise sequence distance computation using dynamic programming. This results in an implementation with significant runtime savings on a standard off-the-shelf FPGA.\",\n \"Title: DecGPU: distributed error correction on massively parallel graphics processing units using CUDA and MPI.\\nYear: 2011\\n\\nAbstract: Next-generation sequencing technologies have led to the high-throughput production of sequence data (reads) at low cost. However, these reads are significantly shorter and more error-prone than conventional Sanger shotgun reads. This poses a challenge for the de novo assembly in terms of assembly quality and scalability for large-scale short read datasets.We present DecGPU, the first parallel and distributed error correction algorithm for high-throughput short reads (HTSRs) using a hybrid combination of CUDA and MPI parallel programming models. DecGPU provides CPU-based and GPU-based versions, where the CPU-based version employs coarse-grained and fine-grained parallelism using the MPI and OpenMP parallel programming models, and the GPU-based version takes advantage of the CUDA and MPI parallel programming models and employs a hybrid CPU+GPU computing model to maximize the performance by overlapping the CPU and GPU computation. The distributed feature of our algorithm makes it feasible and flexible for the error correction of large-scale HTSR datasets. Using simulated and real datasets, our algorithm demonstrates superior performance, in terms of error correction quality and execution speed, to the existing error correction algorithms. Furthermore, when combined with Velvet and ABySS, the resulting DecGPU-Velvet and DecGPU-ABySS assemblers demonstrate the potential of our algorithm to improve de novo assembly quality for de-Bruijn-graph-based assemblers.DecGPU is publicly available open-source software, written in CUDA C++ and MPI. The experimental results suggest that DecGPU is an effective and feasible error correction algorithm to tackle the flood of short reads produced by next-generation sequencing technologies.\",\n \"Title: M2E: a multiple-input, multiple-output function extension for RISC-Based extensible processors\\nYear: 2006\\n\\nAbstract: Recent study shows that a further speedup can be achieved by RISC-based extensible processors if the incorporated custom functional units (CFUs) can execute functions with more than two inputs and one output. However, mechanisms to execute multiple-input, multiple-output (MIMO) custom functions in a RISC processor have not been addressed. This paper proposes an extension for single-issue RISC processors based on a CFU that can execute custom functions with up to six inputs and three outputs. To minimize the change to the core processor, we maintain the operand bandwidth of two inputs, one output per cycle and transfer the extra operands and results using repeated custom instructions. While keeping such an limit sacrifices some speedup, our experiments show that the MIMO extension can still achieve an average 51% increase in speedup compared to a dual-input, single-output (DISO) extension and an average 27% increase in speedup compared to a multiple-input, single-output (MISO) extension.\",\n \"Title: Hyper customized processors for bio-sequence database scanning on FPGAs\\nYear: 2005\\n\\nAbstract: Protein sequences with unknown functionality are often compared to a set of known sequences to detect functional similarities. Efficient dynamic-programming algorithms exist for solving this problem, however current solutions still require significant scan times. These scan time requirements are likely to become even more severe due to exponential database growth. In this paper we present a new approach to bio-sequence database scanning using re-configurable FPGA-based hardware platforms to gain high performance at low cost. Efficient mappings of the Smith-Waterman algorithm using fine-grained parallel processing elements (PEs) that are tailored towards the parameters of a query have been designed. We use customization opportunities available at run-time to dynamically hyper customize the systolic array to make better use of available resource. Our FPGA implementation achieves a speedup of approximately 170 for linear gap penalties and 125 for affine gap penalties as compared to a standard desktop computing platform. We show how hyper-customization at run-time can be used to further improve the performance.\",\n \"Title: An FPGA Model for Developing Dynamic Circuit Computing\\nYear: 2005\\n\\nAbstract: Computing on SRAM based FPGAs is set to challenge the Instruction Set Architecture (ISA) computing paradigm in the high-performance computing arena. Dynamic Circuit Computing (DCC) techniques increase efficient use of an FPGA. However, the rapid prototyping heritage of the FPGA has resulted in software that is inadequate for exploiting this potential to be a flexible computing platform. A major barrier to the increased use of high performance computing on FPGA is the high computational overhead associated with the management of a DCC system. The ability to explore new approaches in compiler and execution environment design is crucial in order to reduce these overheads. In this paper we report on the development of an open FPGA architecture model and open source compiler tools for the exploration of the complex interaction between the architecture, compiler and execution environment for DCC on FPGA.\",\n \"Title: A flann-based controller for maximum power point tracking in PV systems under rapidly changing conditions\\nYear: 2012\\n\\nAbstract: In order to increase the efficiency of the Photovoltaic (PV) system, the PV system should be operated at the Maximum Power Point (MPP). The MPP Tracking (MPPT) is an essential part in achieving this improvement. Some of the existing techniques such as Perturb-and-Observe (P&O) and Incremental Conductance (INC) are relatively simpler to implement, but under rapidly changing irradiance and temperature conditions, they fail to track the MPP. Although methods such as Multilayer Perceptron (MLP) and Fuzzy Logic (FL) are efficient in tracking the MPP, their implementation increases the system complexity. In this paper, we propose a novel artificial intelligence based controller for MPPT, which can efficiently track the MPP, while keeping the computational complexity within the limits. Our technique uses Functional Link Artificial Neural Network (FLANN) to predict the PV output voltage at the MPP. Since there is no hidden layer, FLANN is computationally inexpensive. Simulation results verify that the proposed FLANN controller is computationally less intensive and exhibits higher efficiency under rapidly changing weather conditions.\",\n \"Title: Microkernel hypervisor for a hybrid ARM-FPGA platform\\nYear: 2013\\n\\nAbstract: Reconfigurable architectures have found use in a wide range of application domains, but mostly as static accelerators for computationally intensive functions. Commodity computing adoption has not taken off due primarily to design complexity challenges. Yet reconfigurable architectures offer significant advantages in terms of sharing hardware between distinct isolated tasks, under tight time constraints. Trends towards amalgamation of computing resources in the automotive and aviation domains have so far been limited to non-critical systems, because processor approaches suffer from a lack of predictability and isolation. Hybrid reconfigurable platforms may provide a promising solution to this, by allowing physically isolated access to hardware resources, and support for computationally demanding applications, but with improved programmability and management. We propose virtualized execution and management of software and hardware tasks using a microkernel-based hypervisor running on a commercial hybrid computing platform (the Xilinx Zynq). We demonstrate a framework based on the CODEZERO hypervisor, which has been modified to leverage the capabilities of the FPGA fabric. It supports discrete hardware accelerators, dynamically reconfigurable regions, and regions of virtual fabric, allowing for application isolation and simpler use of hardware resources. A case study demonstrating multiple independent (and isolated) software and hardware tasks is presented.\",\n \"Title: CUSHAW: a CUDA compatible short read aligner to large genomes based on the Burrows-Wheeler transform.\\nYear: 2012\\n\\nAbstract: Motivation: New high-throughput sequencing technologies have promoted the production of short reads with dramatically low unit cost. The explosive growth of short read datasets poses a challenge to the mapping of short reads to reference genomes, such as the human genome, in terms of alignment quality and execution speed. Results: We present CUSHAW, a parallelized short read aligner based on the compute unified device architecture (CUDA) parallel programming model. We exploit CUDA-compatible graphics hardware as accelerators to achieve fast speed. Our algorithm uses a quality-aware bounded search approach based on the Burrows-Wheeler transform (BWT) and the Ferragina-Manzini index to reduce the search space and achieve high alignment quality. Performance evaluation, using simulated as well as real short read datasets, reveals that our algorithm running on one or two graphics processing units achieves significant speedups in terms of execution time, while yielding comparable or even better alignment quality for paired-end alignments compared with three popular BWT-based aligners: Bowtie, BWA and SOAP2. CUSHAW also delivers competitive performance in terms of single-nucleotide polymorphism calling for an Escherichia coli test dataset.\",\n \"Title: An improved common subexpression elimination method for reducing logic operators in FIR filter implementations without increasing logic depth\\nYear: 2010\\n\\nAbstract: It is well known that common subexpression elimination techniques minimize the two main cost metrics namely logic operators and logic depths in realizing finite impulse response (FIR) filters. Two classes of common subexpressions occur in the canonic signed digit representation of filter coefficients, called the horizontal and the vertical subexpressions. Previous works have not addressed the trade-offs in using these two types of subexpressions on the logic depth and the number of logic operators of coefficient multipliers. In this paper, we analyze the impact of the horizontal and the vertical common subexpression elimination techniques on reducing the logic depth and number of logic operators in FIR filters. Further, we present an algorithm to optimize the common subexpression elimination that produces FIR filters with fewer numbers of logic operators when compared with other common subexpression elimination algorithms in literature. The design examples show that the average reduction of logic operators achieved using our method over the weight-2 horizontal common subexpression elimination method which produced the best trade-off between logic operators and logic depth (contention resolution algorithm, CRA-2 [F. Xu, C.-H. Chang, C.-C. Jong, Contention resolution algorithm for common subexpression elimination in digital filter design, IEEE Trans. Circuit Syst. II 52(10) (2005) 695-700 (October)]) is 15%. This reduction of logic operators is achieved without any increase in the logic depth. When compared with the recently proposed multiple adder graph (MAG) algorithm [Jeong-Ho Han, In-Cheol Park, FIR filter synthesis considering multiple adder graphs for a coefficient, IEEE Trans. Comput.-Aid. Design Integ. Circuit Syst. 27(5) (2008) 958-962 (May)], the average reduction of logic operators obtained using our method is 5% and the reduction of logic depth is 25%.\",\n \"Title: High Speed Biological Sequence Analysis With Hidden Markov Models On Reconfigurable Platforms\\nYear: 2009\\n\\nAbstract: Molecular biologists use hidden Markov models (HMMs) as a popular tool to statistically describe biological sequence families. This statistical description can then be used for sensitive and selective database scanning, e. g., new protein sequences are compared with a set of HMMs to detect functional similarities. Efficient dynamic-programming algorithms exist for solving this problem; however, current solutions still require significant scan times. These scan time requirements are likely to become even more severe due to the rapid growth in the size of these databases. This paper shows how reconfigurable architectures can be used to derive an efficient fine-grained parallelization of the dynamic programming calculation. We describe how this technique leads to significant runtime savings for HMM database scanning on a standard off-the-shelf field-programmable gate array (FPGA).\",\n \"Title: Performance-Power Design Space Exploration in a Hybrid Computing Platform Suitable for Mobile Applications\\nYear: 2011\\n\\nAbstract: Mobile platforms have started to employ FPGA based hardware accelerators to address the ever-increasing demand for computing performance. For many applications, the use of an operating system on the hardware platform proves beneficial for reasons of better resource management and more robust security. This paper evaluates the performance-power implications in a signal processing algorithm with respect to the introduction of Linux OS on two different architectures (a CPU-based and an FPGA-based hybrid architecture). The results reveal that there is a 22 times improvement in energy budget between the CPU-based implementation and the FPGA-based hybrid implementation, with a negligible performance degradation due to the introduction of Linux OS.\",\n \"Title: Parallel reconstruction of neighbor-joining trees for large multiple sequence alignments using CUDA\\nYear: 2009\\n\\nAbstract: Computing large multiple protein sequence alignments using progressive alignment tools such as ClustalW requires several hours on state-of-the-art workstations. ClustalW uses a three-stage processing pipeline: (i) pairwise distance computation; (ii) phylogenetic tree reconstruction; and (iii) progressive multiple alignment computation. Previous work on accelerating ClustalW was mainly focused on parallelizing the first stage and achieved good speedups for a few hundred input sequences. However, if the input size grows to several thousand sequences, the second stage can dominate the overall runtime. In this paper, we present a new approach to accelerating this second stage using graphics processing units (GPUs). In order to derive an efficient mapping onto the GPU architecture, we present a parallelization of the neighbor-joining tree reconstruction algorithm using CUDA. Our experimental results show speedups of over 26times for large datasets compared to the sequential implementation.\",\n \"Title: MSAProbs: multiple sequence alignment based on pair hidden Markov models and partition function posterior probabilities.\\nYear: 2010\\n\\nAbstract: Motivation: Multiple sequence alignment is of central importance to bioinformatics and computational biology. Although a large number of algorithms for computing a multiple sequence alignment have been designed, the efficient computation of highly accurate multiple alignments is still a challenge. Results: We present MSAProbs, a new and practical multiple alignment algorithm for protein sequences. The design of MSAProbs is based on a combination of pair hidden Markov models and partition functions to calculate posterior probabilities. Furthermore, two critical bioinformatics techniques, namely weighted probabilistic consistency transformation and weighted profile-profile alignment, are incorporated to improve alignment accuracy. Assessed using the popular benchmarks: BAliBASE, PREFAB, SABmark and OXBENCH, MSAProbs achieves statistically significant accuracy improvements over the existing top performing aligners, including ClustalW, MAFFT, MUSCLE, ProbCons and Probalign. Furthermore, MSAProbs is optimized for multi-core CPUs by employing amulti-threaded design, leading to a competitive execution time compared to other aligners.\",\n \"Title: C2FPGA-A dependency-timing graph design methodology\\nYear: 2013\\n\\nAbstract: In this paper, we present a design methodology that uses a combined graphical and scheduling technique to map C-based high level language (HLL) based applications to FPGA. Although there are a number of approaches addressing the mapping from HLL to hardware, many of these existing solutions either require a steep learning curve or do not produce an appropriate mapping pattern for the hardware platform. We provide a solution to this problem, by analyzing the data flow and data dependencies in the given code and proposing a scheduling patterns for the given algorithm. We then provide a suitable mapping pattern for the hardware platform. We use the mapping pattern to deliver synthesizable HDL (Verilog) code. We demonstrate our design methodology with results from different real-time case studies that are based on different algorithms.\",\n \"Title: Automatic Identification of Custom Functions for Embedded Processors with MIMO Extensions\\nYear: 2006\\n\\nAbstract: Commercially available configurable processors nowadays offer opportunities to accelerate embedded applications by implementing customized functions. Previous studies have shown that more speedup can be achieved if these functions are allowed to have more than two inputs and one output. However, automatic identification of multiple-input, multiple-output (MIMO) custom functions is usually slow due to the large exploration space. In this paper, we propose a fast algorithm to enumerate all convex subgraphs that satisfy the input/output constraints from the dataflow graph (DFG) of a basic block. The algorithm can be tuned to determine all subgraphs or only those connected subgraphs. This allows a choice between a better instruction set extension or a faster design space exploration. The algorithm's run time can be orders of magnitude better than previous algorithms when a custom function is allowed to have two or more outputs\",\n \"Title: CUDA-MEME: Accelerating motif discovery in biological sequences using CUDA-enabled graphics processing units\\nYear: 2010\\n\\nAbstract: Motif discovery in biological sequences is of prime importance and a major challenge in computational biology. Consequently, numerous motif discovery tools have been developed to date. However, the rapid growth of both genomic sequence and gene transcription data, establishes the need for the development of scalable motif discovery tools. An approach to improve the runtime of motif discovery by an order-of-magnitude without losing sensitivity is to employ emerging many-core architectures such as CUDA-enabled GPUs. In this paper, we present a highly parallel formulation and implementation of the MEME motif discovery algorithm using the CUDA programming model. To achieve high efficiency, we introduce two parallelization approaches: sequence-level and substring-level parallelization. Furthermore, a hybrid computing framework is described to take advantage of both CPU and GPU compute resources. Our performance evaluation on a GeForce GTX 280 GPU, results in average runtime speedups of 21.4 (19.3) for the starting point search and 20.5 (16.4) for the overall runtime using the OOPS (ZOOPS) motif search model. The runtime speedups of CUDA-MEME on a single GPU are also comparable to those of ParaMEME running on 16 CPU cores of a high-performance workstation cluster. In addition to the fast speed, CUDA-MEME has the capability of finding motif instances consistent with the sequential MEME.\",\n \"Title: A technique for expressing IT security objectives\\nYear: 2006\\n\\nAbstract: At the specification phase, the developer of an IT security product identifies and documents applicable security objectives. Specifications are often intuitive and hard to assess and while being syntactically correct may still fail to appropriately capture the security problem addressed. A technique is proposed for expressing Common Criteria compliant security environments and security objectives for high assurance IT security products. The technique is validated by an analysis of the security specification for a device computing digital signatures within the European Union PKI framework. Modifications to the specification are proposed and the possibility of extending the CC treatment of security objectives is discussed.\",\n \"Title: EpiList II: Closing the Loop in the Development of Generic Cognitive Skills\\nYear: 2010\\n\\nAbstract: The importance of cognitive skills in human learning and reasoning has become well established in recent years. This motivates the search for a knowledge representation that supports the development of a computational algorithm that performs, as well as instructs such cognitive skills. Cognitive skills can be broadly divided into two types: specific and generic cognitive skills. Intelligent tutoring systems (ITSs) that develop generic cognitive skills are essential for developing classification, generalization, and comparison processes. However, these current systems are inherently open loop and do not utilize feedback, based on the student's competence level, to adapt the learning process. This is a major drawback when attempting to provide a dynamic learner-focused approach for effective instruction. In this paper, we present EpiList II, an ITS that closes the loop and is hence able to monitor and dynamically assess the student's cognitive-skill competence. The results show a significant improvement in positive- and negative-reasoning skills, with 51% of students (up from an average of 8% of students when using an open-loop ITS) acquiring/developing these skills.\",\n \"Title: Fourth Workshop On Using Emerging Parallel Architectures\\nYear: 2012\\n\\nAbstract: The Fourth Workshop on Using Emerging Parallel Architectures (WEPA), held in conjunction with ICCS 2012, provides a forum for exploring the capabilities of emerging parallel architectures such as GPUs, FPGAs, Cell B. E., Intel M. I. C. and multi-cores to accelerate computational science applications.\",\n \"Title: A Brain Inspired Fuzzy Neuro-Predictor For Bank Failure Analysis\\nYear: 2006\\n\\nAbstract: Bank failure prediction is important to bank regulators, including central banks and financial ministries. Off-site surveillance systems or early warning models use financial statements or other rating systems to assess the financial status of the banks. Statistical based bank failure prediction models assume a normal probability distribution and equal dispersion on the data that is often violated. Neural network (NN) based models do not make these assumptions about the data. NNs give better prediction results, however, they lack explanatory capabilities. Fuzzy-neural networks (FNN), allow explanatory capabilities and give better performance. In this paper, several bank failure prediction models using the pseudo outer product-based FNN with a compositional rule of inference and singleton fuzzifier (POPFNN-CRI(S)) are proposed. The system uses financial covariates derived from publicly available financial statements to predict failing banks. The performances of the models are assessed through the classification of 3636 US banks for one-year and two-year periods. As it is not possible to obtain all financial statements, we also propose a model to aid in the reconstruction of missing financial data using POPFNN-CRI(S). To complete the study, the effect that missing data has on the outcome of bank failure prediction is examined.\",\n \"Title: Using reconfigurable hardware to accelerate multiple sequence alignment with ClustalW\\nYear: 2005\\n\\nAbstract: Summary: Aligning hundreds of sequences using progressive alignment tools such as ClustalW requires several hours on state-of-the-art workstations. We present a new approach to compute multiple sequence alignments in far shorter time using reconfigurable hardware. This results in an implementation of ClustalW with significant runtime savings on a standard off-the-shelf FPGA. Availability: An online server for ClustalW running on a Pentium IV 3 GHz with a Xilinx XC2V6000 FPGA PCI-board is available at http://beta.projectproteus.org. The PE hardware design in Verilog HDL is available on request from the first author. Contact: tim.oliver@pmail.ntu.edu.sg\",\n \"Title: High-speed Multiple Sequence Alignment on a reconfigurable platform\\nYear: 2006\\n\\nAbstract: Progressive alignment is a widely used approach to compute multiple sequence alignments (MSAs). However, aligning several hundred sequences by popular progressive alignment tools requires hours on sequential computers. Due to the rapid growth of sequence databases biologists have to compute MSAs in a far shorter time. In this paper we present a new approach to MSA on reconfigurable hardware platforms to gain high performance at low cost. We have constructed a linear systolic array to perform pairwise sequence distance computations using dynamic programming. This results in an implementation with significant runtime savings on a standard FPGA.\",\n \"Title: iDEA: A DSP block based FPGA soft processor\\nYear: 2012\\n\\nAbstract: This paper presents a very lean DSP Extension Architecture (iDEA) soft processor for Field Programmable Gate Arrays (FPGAs). iDEA has been built to be as lightweight as possible, utilising the run-time flexibility of the DSP48E1 primitive in Xilinx FPGAs to serve as many processor functions as possible. We show how the primitive's flexibility can be leveraged within a general-purpose processor, what additional circuitry is needed, and present a full instruction-set architecture. The result is a very compact processor that can run at high speed, while executing a full gamut of general machine instructions. We provide results for a number of simple applications, and show how the processor's resource requirements and frequency compare to a Xilinx MicroBlaze soft core. Based on the DSP48E1, this processor can be deployed across next-generation Xilinx Artix-7, Kintex-7, and Virtex-7 families.\",\n \"Title: An Ultrafast Scalable Many-Core Motif Discovery Algorithm for Multiple GPUs\\nYear: 2011\\n\\nAbstract: The identification of genome-wide transcription factor binding sites is a fundamental and crucial problem to fully understand the transcriptional regulatory processes. However, the high computational cost of many motif discovery algorithms heavily constraints their application for large-scale datasets. The rapid growth of genomic sequences and gene transcription data further deteriorates the situation and establishes a strong requirement for time-efficient scalable motif discovery algorithms. The emergence of many-core architectures, typically CUDA-enabled GPUs, provides an opportunity to reduce the execution time by an order of magnitude without the loss of accuracy. In this paper, we present mCUDA-MEME, an ultrafast scalable many-core motif discovery algorithm for multiple GPUs based on the MEME algorithm. Our algorithm is implemented using a hybrid combination of the CUDA, OpenMP and MPI parallel programming models in order to harness the powerful compute capability of modern GPU clusters. At present, our algorithm supports OOPS and ZOOPS models, which are sufficient for most motif discovery applications. mCUDAMEME achieves significant speedups for the starting point search stage (and the overall execution) when benchmarked, using real datasets, against parallel MEME running on 32 CPU cores. Speedups of up to 1.4 (1.1) on a single GPU of a Fermi-based Tesla S2050 quad-GPU computing system and up to 10.8 (8.3) on the eight GPUs of a two Tesla S2050 system were observed. Furthermore, our algorithm shows good scalability with respect to dataset size and the number of GPUs (availability:https://sites.google.com/site/yongchaosoftware/mc uda-meme).\",\n \"Title: Parallelized short read assembly of large genomes using de Bruijn graphs.\\nYear: 2011\\n\\nAbstract: Next-generation sequencing technologies have given rise to the explosive increase in DNA sequencing throughput, and have promoted the recent development of de novo short read assemblers. However, existing assemblers require high execution times and a large amount of compute resources to assemble large genomes from quantities of short reads.We present PASHA, a parallelized short read assembler using de Bruijn graphs, which takes advantage of hybrid computing architectures consisting of both shared-memory multi-core CPUs and distributed-memory compute clusters to gain efficiency and scalability. Evaluation using three small-scale real paired-end datasets shows that PASHA is able to produce more contiguous high-quality assemblies in shorter time compared to three leading assemblers: Velvet, ABySS and SOAPdenovo. PASHA's scalability for large genome datasets is demonstrated with human genome assembly. Compared to ABySS, PASHA achieves competitive assembly quality with faster execution speed on the same compute resources, yielding an NG50 contig size of 503 with the longest correct contig size of 18,252, and an NG50 scaffold size of 2,294. Moreover, the human assembly is completed in about 21 hours with only modest compute resources.Developing parallel assemblers for large genomes has been garnering significant research efforts due to the explosive size growth of high-throughput short read datasets. By employing hybrid parallelism consisting of multi-threading on multi-core CPUs and message passing on compute clusters, PASHA is able to assemble the human genome with high quality and in reasonable time using modest compute resources.\",\n \"Title: Supporting multiple-input, multiple-output custom functions in configurable processors\\nYear: 2007\\n\\nAbstract: Configurable processors have emerged as a promising solution for high performance embedded systems. Many of these processors extend a RISC core with configurable functional units that execute dual-input, single-output (DISO) custom functions. Although studies have shown that supporting multiple-input, multiple-output (MIMO) custom functions can lead to significant speedups, mechanisms to efficiently achieve this have not been adequately addressed. The underlying reason is that a custom function is normally invoked by a single instruction, which usually transfers only two inputs and one output. Attempts to transfer more inputs and outputs in one instruction are impeded by the instruction length and the register file's R/W ports. This paper proposes a simple extension to transfer multiple inputs and outputs of the custom functions using repeated instructions. While transferring the inputs and outputs may take a few extra cycles, our experiments show that the MIMO extension can still achieve an average 51% increase in speedup compared to a DISO extension and an average 27% increase in speedup compared to a multiple-input, single-output (MISO) extension.\",\n \"Title: A dependency graph based methodology for parallelizing HLL applications on FPGA (abstract only)\\nYear: 2010\\n\\nAbstract: Reconfigurable computing is an exciting new area of research. It opens up a number of new computing paradigms with the potential to significantly change the embedded computing landscape. Unfortunately, as with any new concept, there is much to be done before it can be brought into the mainstream. Reconfigurable computing needs to be made more usable by the general computing community by making the application mapping process more user transparent. We need to be able to efficiently exploit the parallelism and high communications bandwidth available in reconfigurable computing systems, such as provided by FPGA devices. In this paper we propose a framework to map C-based applications to an FPGA based system. The framework relies on dependency based analysis information obtained from a high level Intermediate Representation (IR) of the C-Application. The dependencies have a major impact on the instruction flow and the parallelism of the algorithms when implemented on FPGA based high performance computing platforms. We demonstrate the importance of these dependencies in algorithms by examining a compute intensive bio-informatics application. Targeting on a Xilinx Virtex 5 XC5VFX70T FPGA, our place and route results achieved 92% of the clock frequency achieved by using a manual design of the same application. The contribution in this paper is to provide a semi-automated approach to generate hardware for FPGA based systems through a high level data dependency graphical IR.\",\n \"Title: A Fast High-Level Event-Driven Thermal Estimator for Dynamic Thermal Aware Scheduling\\nYear: 2012\\n\\nAbstract: Thermal aware scheduling (TAS) is an important system level optimization for many-core systems. A fast event driven thermal estimation method, which includes both the dynamic and leakage power models, for monitoring temperature and guiding dynamic TAS (DTAS) is proposed in this paper. The fast event driven thermal estimation is based upon a thermal map, with occasional thermal sensor-based calibration, which is updated only when a high level event occurs. To minimize the overhead, while maintaining the estimation accuracy, prebuilt look-up-tables and predefined leakage calibration parameters are used to speed up the thermal solution. Experimental results show our method is accurate, producing thermal estimations of similar quality to an existing open-source thermal simulator, while having a considerably reduced computational complexity. Based on this predictive approach, we take full advantage of a projected future thermal map to develop several heuristic policies for DTAS. We show that our proposed predictive policies are significantly better, in terms of minimizing average/peak temperature, reducing the dynamic thermal management overhead and improving other real-time features, than existing DTAS schedulers, making them highly suitable for heuristically guiding thermal aware task allocation and scheduling.\",\n \"Title: Accelerating the viterbi algorithm for profile hidden markov models using reconfigurable hardware\\nYear: 2006\\n\\nAbstract: Profile Hidden Markov Models (PHMMs) are used as a popular tool in bioinformatics for probabilistic sequence database searching. The search operation consists of computing the Viterbi score for each sequence in the database with respect to a given query PHMM. Because of the rapid growth of biological sequence databases, finding fast solutions is of highest importance to research in this area. Unfortunately, the required scan times of currently available sequential software implementations are very high. In this paper we show how reconfigurable hardware can be used as a computational platform to accelerate this application by two orders of magnitude.\",\n \"Title: Fcmac-Aars: A Novel Fnn Architecture For Stock Market Prediction And Trading\\nYear: 2006\\n\\nAbstract: A novel fuzzy neural network architecture, the approximate analogical reasoning based fuzzy CMAC (FCMAC-AARS), is proposed. AARS is incorporated into the fuzzy CMAC structure as it is conceptually clearer and more computationally efficient than the CRI and TVR fuzzy inference schemes. A prediction and trading framework has been proposed which exploits the price percentage oscillator (PPO) for input preprocessing and trading decision making. Numerical experiments conducted on real-life stock data confirm the validity of the design and the performance of the FCMAC-AARS system.\",\n \"Title: A Reconfigurable Bloom Filter Architecture for BLASTN\\nYear: 2009\\n\\nAbstract: Efficient seed-based filtration methods exist for scanning genomic sequence databases. However, current solutions require a significant scan time on traditional computer architectures. These scan time requirements are likely to become even more severe due to the rapid growth in the size of databases. In this paper, we present a new approach to genomic sequence database scanning using reconfigurable field-programmable gate array (FPGA)-based hardware. To derive an efficient mapping onto this type of architecture, we propose a reconfigurable Bloom filter architecture. Our experimental results show that the FPGA implementation achieves an order of magnitude speedup compared to the NCBI BLASTN software running on a general purpose computer.\",\n \"Title: Prerouted FPGA cores for rapid system construction in a dynamic reconfigurable system\\nYear: 2007\\n\\nAbstract: A method of constructing prerouted FPGA cores, which lays the foundations for a rapid system construction framework for dynamically reconfigurable computing systems, is presented. Two major challenges are considered: how tomanage the wires crossing a core's borders; and how to maintain an acceptable level of flexibility for system construction with only a minimum of overhead. In order to maintain FPGA computing performance, it is crucial to thoroughly analyze the issues at the lowest level of device detail in order to ensure that computing circuit encapsulation is as efficient as possible. We present the first methodology that allows a core to scale its interface bandwidth to the maximum available in a routing channel. Cores can be constructed independently from the rest of the system using a framework that is independent of the method used to place and route primitive components within the core. We use an abstract FPGA model and CAD tools that mirror those used in industry. An academic design flow has been modified to include a wire policy and an interface constraints framework that tightly constrains the use of the wires that cross a core's boundaries. Using this tool set we investigate the effect of prerouting on overall system optimality. Abutting cores are instantly connected by colocation of interface wires. Eliminating run-time routing drastically reduces the time taken to construct a system using a set of cores.\",\n \"Title: The iDEA DSP Block-Based Soft Processor for FPGAs\\nYear: 2014\\n\\nAbstract: DSP blocks in modern FPGAs can be used for a wide range of arithmetic functions, offering increased performance while saving logic resources for other uses. They have evolved to better support a plethora of signal processing tasks, meaning that in other application domains they may be underutilised. The DSP48E1 primitives in new Xilinx devices support dynamic programmability that can help extend their usefulness; the specific function of a DSP block can be modified on a cycle-by-cycle basis. However, the standard synthesis flow does not leverage this flexibility in the vast majority of cases. The lean DSP Extension Architecture (iDEA) presented in this article builds around the dynamic programmability of a single DSP48E1 primitive, with minimal additional logic to create a general-purpose processor supporting a full instruction-set architecture. The result is a very compact, fast processor that can execute a full gamut of general machine instructions. We show a number of simple applications compiled using an MIPS compiler and translated to the iDEA instruction set, comparing with a Xilinx MicroBlaze to show estimated performance figures. Being based on the DSP48E1, this processor can be deployed across next-generation Xilinx Artix-7, Kintex-7, Virtex-7, and Zynq families.\",\n \"Title: An Improved Robust Field-Weakeaning Algorithm for Direct-Torque-Controlled Synchronous-Reluctance-Motor Drives\\nYear: 2015\\n\\nAbstract: This paper presents an improved field weakening (FW) algorithm for synchronous-reluctance-motor drives. The proposed algorithm is robust to the variations in the machine d- and q-axis inductances. The transition between the maximum torque per ampere, current and voltage limits, and the maximum torque per flux trajectories is smooth. The proposed technique is combined with the direct-torque-control method to attain a high performance drive in the FW region. Simulation and experimental results are supplemented to verify the effectiveness of the proposed approach.\",\n \"Title: Virtualized Execution and Management of Hardware Tasks on a Hybrid ARM-FPGA Platform\\nYear: 2014\\n\\nAbstract: Emerging hybrid reconfigurable platforms tightly couple capable processors with high performance reconfigurable fabrics. This promises to move the focus of reconfigurable computing systems from static accelerators to a more software oriented view, where reconfiguration is a key enabler for exploiting the available resources. This requires a revised look at how to manage the execution of such hardware tasks within a processor-based system, and in doing so, how to virtualize the resources to ensure isolation and predictability. This view is further supported by trends towards amalgamation of computation in the automotive and avionics domains, where such properties are essential to overall system reliability. We present the virtualized execution and management of software and hardware tasks using a microkernel-based hypervisor running on a commercial hybrid computing platform (the Xilinx Zynq). The CODEZERO hypervisor has been modified to leverage the capabilities of the FPGA fabric, with support for discrete hardware accelerators, dynamically reconfigurable regions, and regions of virtual fabric. We characterise the communication overheads in such a hybrid system to motivate the importance of lean management, before quantifying the context switch overhead of the hypervisor approach. We then compare the resulting idle time for a standard Linux implementation and the proposed hypervisor method, showing two orders of magnitude improved performance with the hypervisor.\",\n \"Title: A uniform implementation scheme for evolutionary optimization algorithms and the experimental implementation of an ACO based MPPT for PV systems under partial shading\\nYear: 2014\\n\\nAbstract: Partial shading is one of the important issues in maximum power point (MPP) tracking (MPPT) for photovoltaic (PV) systems. Multiple peaks on the power-voltage (P-V) curve under partial shading conditions can result in a conventional MPPT technique failing to track the global MPP, thus causing large power losses. Whereas, evolutionary optimization algorithms exhibit many advantages when applying them to MPPT, such as, the ability to track the global MPP, no requirement for irradiance or temperature sensors, system independence without knowledge of the PV system in advance, reduced current/voltage sensors compared to conventional methods when applied to PV systems with a distributed MPPT structure. This paper presents a uniform scheme for implementing evolutionary algorithms into the MPPT under various PV array structures. The effectiveness of the proposed method is verified both by simulations and experimental setup. The implementation of the ant colony optimization (ACO) based MPPT is conducted using this uniform scheme. In addition, a strategy to accelerate the convergence speed, which is important in systems with partial shading caused by rapid irradiance change, is also discussed.\",\n \"Title: A hardware efficient implementation of an adaptive subsample delay estimator\\nYear: 2004\\n\\nAbstract: A real-time algorithm for estimating the subsample delay between two noisy sinusoidal signals is presented. The new technique is based on the recently proposed discrete-time quadrature delay estimator (QDE). The algorithm uses all of the in-phase and quadrature-phase components of the received signals to produce a bias-free estimate of the delay between the input signals. The technique directly updates the delay error estimate, which is in turn used to adapt the coefficients of a simple fractional delay filter (FDF). The algorithm is insensitive to variations in the amplitudes of the input signals, and does not require an accurate estimate of the frequency of the input sinusoids. The technique is simple to implement and has a significantly reduced complexity compared to other adaptive techniques. Simulations show that in the presence of system noise, the new estimator outperforms conventional fractional delay filter based estimators.\",\n \"Title: The design of multiplierless FIR filters with a minimum adder step and reduced hardware complexity\\nYear: 2006\\n\\nAbstract: We propose an algorithm for reducing the hardware complexity of linear phase FIR digital filters without resorting to an increase in the number of adder steps in the multiplier block adders. We aggressively reduce both the coefficient wordlength and the number of non-zero bits in the filter coefficients so that the adder step can be minimized. The hardware implementation of the coefficients is such that the number of full adders is proportional to the product of the input signal wordlength and the number of adders. That is, in general, the number of full adders is independent of the coefficient wordlength and the number of shifts between nonzero bits in the coefficient. Results show that the proposed technique achieves a 67% and 71% reduction in the number of multiplier block adders and the number of multiplier block full adders respectively. Our technique has been successfully applied to filters with up to 500 taps\",\n \"Title: Software-Oriented Approach to Hardware-Software Co-Simulation for FPGA-Based Risc Extensible Processor\\nYear: 2006\\n\\nAbstract: Recent advancements in mixed hardware-software modeling platforms have simplified the process of concurrently modeling complex algorithms in hardware while considering the software generation in an integrated environment. To efficiently facilitate design space exploration for RISC extensible processors, it is imperative to use a tightly coupled hardware-software co-design and modeling effort that also maintains the flexibility for exploring other types of microarchitectures. We have introduced a simulation framework using a software-oriented design methodology that can be adopted to model the software and hardware components in a reconfigurable co-processor. Experiments on some commonly used DSP and image processing tasks show that hardware-software trade-offs in the various models can be efficiently analyzed during the initial design phase.\",\n \"Title: Execution Objects for Dynamically Reconfigurable FPGA Systems\\nYear: 2006\\n\\nAbstract: This paper explores the use of pre-routed cores as execution objects in an object-oriented programming model and execution environment for dynamic computing on FPGA. In order to maintain FPGA computing performance it is crucial to thoroughly analyze the issues at the lowest level of device detail in order to ensure that computing circuit encapsulation is as efficient as possible. The first methodology that allows a core to scale its interface bandwidth to the maximum available in a routing channel was presented. Cores can be constructed independently from the rest of the system using a framework that is independent of the method used to place and route primitive components within the core. The authors used an architecture model and CAD tools that mirror those used in industry. Abutting cores are instantly connected by co-location of interface wires. Eliminating run-time routing drastically reduces the time taken to construct a system using a set of cores. It was illustrated how, although pre-routing has an adverse impact on core performance by up to 14%, it can improve functional density by up to six times for rapid reconfiguration\",\n \"Title: Type-2 GA-TSK fuzzy neural network\\nYear: 2007\\n\\nAbstract: A novel fuzzy-neural network, the type-2 GA- TSKfnn (T2GA-TSKfnn), combining a type-2 fuzzy logic system (FLS) and a genetic algorithm (GA) based Takagi-Sugeno- Kang fuzzy neural network (GA-TSKfnn), is presented. The rational for this combination is that type-2 fuzzy sets are better able to deal with rule uncertainties, while the optimal GA-based tuning of the T2GA-TSKfnn parameters achieves better classification results. However, a general T2GA-TSKfnn is computationally very intensive due to the complexity of the type-2 to type-1 reduction. Therefore, we adopt an interval T2GA-TSKfnn implementation to simplify the computational process. Simulation results are provided to compare the T2GA-TSKfnn against other fuzzy neural networks. These results show that the proposed system is able to achieve a higher classification rate when compared against a number of other traditional neuro-fuzzy classifiers.\",\n \"Title: Efficient multiplierless channel filters for multi-standard SDR\\nYear: 2008\\n\\nAbstract: This paper investigates the design of very low complexity multiplierless linear phase FIR filters for use in the channelizer of multi-standard software defined radios. A technique for reducing the hardware complexity of linear phase FIR digital filters which minimizes the adder depth and the number of adders in the multiplier block is introduced and is used to implement a multistage, multi-standard decimating filter. The design reuses components for different communications standards and is thus ideal for use in systems which support dynamic reconfiguration.\",\n \"Title: Reconfigurable Accelerator for the Word-Matching Stage of BLASTN\\nYear: 2013\\n\\nAbstract: BLAST is one of the most popular sequence analysis tools used by molecular biologists. It is designed to efficiently find similar regions between two sequences that have biological significance. However, because the size of genomic databases is growing rapidly, the computation time of BLAST, when performing a complete genomic database search, is continuously increasing. Thus, there is a clear need to accelerate this process. In this paper, we present a new approach for genomic sequence database scanning utilizing reconfigurable field programmable gate array (FPGA)-based hardware. In order to derive an efficient structure for BLASTN, we propose a reconfigurable architecture to accelerate the computation of the word-matching stage. The experimental results show that the FPGA implementation achieves a speedup around one order of magnitude compared to the NCBI BLASTN software running on a general purpose computer.\",\n \"Title: Current-controlled resonant circuit based photovoltaic micro-inverter with half- wave cycloconverter\\nYear: 2013\\n\\nAbstract: An electronically-controlled series resonant circuit based micro-inverter with a full-bridge inverter and a half-wave cycloconverter is proposed for single phase distributed photovoltaic (PV) systems rated up to 400W. A series resonant circuit and a high frequency transformer are used to couple the full-bridge inverter and the half-wave cycloconverter. Inductor of the series resonant circuit is used to control output current of the micro-inverter. The proposed current control strategy of the micro-inverter is mathematically analyzed. The proposed micro-inverter is simulated using the MATLAB/PLECS block set in order to verify feasibility of the proposed current control method in series resonant circuit based DC-AC converters. Experimental results are obtained to further validate the proposed current control method.\",\n \"Title: A distributed minority and majority voting based redundancy scheme\\nYear: 2015\\n\\nAbstract: This article presents a new distributed minority-cum-majority voting based redundancy (DMMR) scheme that is scalable and has the ability to tolerate multiple function module faults/failures. In comparison with 5-tuple, 7-tuple, and 9-tuple versions of the N-modular redundancy scheme, the proposed DMMR scheme whilst being equally fault-tolerant reports respective improvements in design metrics (i.e., figure-of-merit) by 32.5%, 180.4% and 377.4% for example ASIC-based implementations utilizing a 4×4 array multiplier as the representative function module, whilst reporting very small corresponding decreases in system reliability by just 1.21%, 1.06% and 1.08% for consideration of module reliabilities ranging from 0.9 to 0.99. The simulation results are obtained using a 32/28nm CMOS process.\",\n \"Title: A racetrack memory based in-memory booth multiplier for cryptography application\\nYear: 2016\\n\\nAbstract: Security is an important concern in cloud computing nowadays. RSA is one of the most popular asymmetric encryption algorithms that are widely used in internet based applications for its public key strategy advantage over symmetric encryption algorithms. However, RSA encryption algorithm is very compute intensive, which would affect the speed and power efficiency of the encountered applications. Racetrack Memory (RM) is a newly introduced promising technology in future storage and memory system, which is perfect to be used in memory intensive scenarios because of its high data density. However, novel designs should be applied to exploit the advantages of RM while avoiding the adverse impact of its sequential access mechanism. In this paper, we present an in-memory Booth multiplier based on racetrack memory to alleviate this problem. As the building block of our multiplier, a racetrack memory based adder is proposed, which saves 56.3% power compared with the state-of-the-art magnetic adder. Integrated with the storage element, our proposed multiplier shows great efficiency in area, power and scalability.\",\n \"Title: Efficient Overlay Architecture Based on DSP Blocks\\nYear: 2015\\n\\nAbstract: Design productivity and long compilation times are major issues preventing the mainstream adoption of FPGAs in general purpose computing. Several overlay architectures have emerged to tackle these challenges, but at the cost of increased area and performance overheads. This paper examines a coarse grained overlay architecture designed using the flexible DSP48E1 primitive on Xilinx FPGAs. This allows pipelined execution at significantly higher throughput without adding significant area overheads to the PE. We map several benchmarks, using our custom mapping tool, and show that the proposed overlay architecture delivers a throughput of up to 21.6 GOPS and provides an 11 -- 52% improvement in throughput compared to Vivado HLS implementations.\",\n \"Title: Automatic Fault Detection And Diagnosis For Photovoltaic Systems Using Combined Artificial Neural Network And Analytical Based Methods\\nYear: 2015\\n\\nAbstract: Long term exposure of photovoltaic (PV) systems under relatively harsh and changing environmental conditions can result in fault conditions developing during the operational lifetime. The present solution is for system operators to manually perform condition monitoring of the PV system. However, it is time-consuming, inaccurate and dangerous. Thus, automatic fault detection and diagnosis is a critical task to ensure the reliability and safety in PV systems. The current state-of-the-art techniques either cannot provide enough detailed fault information with high accuracy or have too much complexity. This work presents an automatic fault detection and diagnosis method for string based PV systems. It combines an artificial neural network (ANN) with the conventional analytical method to conduct the fault detection and diagnosis tasks. A two-layered ANN is applied to predict the expected power which is then compared with the measured power from the real PV system. Based on the difference between the ANN estimated power and the measured power, the open circuit voltage and short circuit current of the PV string determined using analytical equations are used to identify any of the six defined fault types. The proposed method has a fast detection, compact structure and good accuracy. Simulation results show the effective fault detection and diagnosis capability of the proposed method.\",\n \"Title: Adapting the DySER Architecture with DSP Blocks as an Overlay for the Xilinx Zynq.\\nYear: 2015\\n\\nAbstract: Coarse-grained overlay architectures have been shown to be effective when paired with general purpose processors, offering software-like programmability, fast compilation, and improved design productivity. These architectures enable general purpose hardware accelerators, allowing hardware design at a higher level of abstraction, but at the cost of area and performance overheads. This paper examines the DySER overlay architecture as a hardware accelerator paired with a general purpose processor in a hybrid FPGA such as the Xilinx Zynq. We evaluate the DySER architecture mapped on the Xilinx Zynq and show that it suffers from a significant area and performance overhead. We then propose an improved functional unit architecture using the flexibility of the DSP48E1 primitive which results in a 2.5 times frequency improvement and 25% area reduction compared to the original functional unit architecture. We demonstrate that this improvement results in the routing architecture becoming the bottleneck in performance.\",\n \"Title: An Area-Efficient FPGA Overlay using DSP Block based Time-multiplexed Functional Units.\\nYear: 2016\\n\\nAbstract: Coarse grained overlay architectures improve FPGA design productivity by providing fast compilation and software-like programmability. Throughput oriented spatially configurable overlays typically suffer from area overheads due to the requirement of one functional unit for each compute kernel operation. Hence, these overlays have often been of limited size, supporting only relatively small compute kernels while consuming considerable FPGA resources. This paper examines the possibility of sharing the functional units among kernel operations for reducing area overheads. We propose a linear interconnected array of time-multiplexed FUs as an overlay architecture with reduced instruction storage and interconnect resource requirements, which uses a fully-pipelined, architecture-aware FU design supporting a fast context switching time. The results presented show a reduction of up to 85% in FPGA resource requirements compared to existing throughput oriented overlay architectures, with an operating frequency which approaches the theoretical limit for the FPGA device.\",\n \"Title: DeCO: A DSP Block Based FPGA Accelerator Overlay with Low Overhead Interconnect\\nYear: 2016\\n\\nAbstract: Coarse-grained FPGA overlay architectures paired with general purpose processors offer a number of advantages for general purpose hardware acceleration because of software-like programmability, fast compilation, application portability, and improved design productivity. However, the area overheads of these overlays, and in particular architectures with island-style interconnect, negate many of these advantages, preventing their use in practical FPGA-based systems. Crucially, the interconnect flexibility provided by these overlay architectures is normally over-provisioned for accelerators based on feed-forward pipelined datapaths, which in many cases have the general shape of inverted cones. We propose DeCO, a cone shaped cluster of FUs utilizing a simple linear interconnect between them. This reduces the area overheads for implementing compute kernels extracted from compute-intensive applications represented as directed acyclic dataflow graphs, while still allowing high data throughput. We perform design space exploration by modeling programmability overhead as a function of overlay design parameters, and compare to the programmability overhead of island-style overlays. We observe 87% savings in LUT requirements using the proposed approach compared to DSP block based island-style overlays. Our experimental evaluation shows that the proposed overlay exhibits an achievable frequency of 395 MHz, close to the DSP theoretical limit on the Xilinx Zynq. We also present an automated tool flow that provides a rapid and vendor-independent mapping of the high level compute kernel code to the proposed overlay.\",\n \"Title: Throughput Oriented Fpga Overlays Using Dsp Blocks\\nYear: 2016\\n\\nAbstract: Design productivity is a major concern preventing the mainstream adoption of FPGAs. Overlay architectures have emerged as one possible solution to this challenge, offering fast compilation and software-like programmability. However, overlays typically suffer from area and performance overheads due to limited consideration for the underlying FPGA architecture. These overlays have often been of limited size, supporting only relatively small compute kernels. This paper examines the possibility of developing larger, more efficient, overlays using multiple DSP blocks and then maximising utilisation by mapping multiple instances of kernels simultaneously onto the overlay to exploit kernel level parallelism. We show a significant improvement in achievable overlay size and overlay utilisation, with a reduction of almost 70% in the overlay tile requirement compared to existing overlay architectures, an operating frequency in excess of 300 MHz, and kernel throughputs of almost 60 GOPS.\",\n \"Title: Resource-Aware Just-in-Time OpenCL Compiler for Coarse-Grained FPGA Overlays.\\nYear: 2017\\n\\nAbstract: FPGA vendors have recently started focusing on OpenCL for FPGAs because of its ability to leverage the parallelism inherent to heterogeneous computing platforms. OpenCL allows programs running on a host computer to launch accelerator kernels which can be compiled at run-time for a specific architecture, thus enabling portability. However, the prohibitive compilation times (specifically the FPGA place and route times) are a major stumbling block when using OpenCL tools from FPGA vendors. The long compilation times mean that the tools cannot effectively use just-in-time (JIT) compilation or runtime performance scaling. Coarse-grained overlays represent a possible solution by virtue of their coarse granularity and fast compilation. In this paper, we present a methodology for run-time compilation of OpenCL kernels to a DSP block based coarse-grained overlay, rather than directly to the fine-grained FPGA fabric. The proposed methodology allows JIT compilation and on-demand resource-aware kernel replication to better utilize available overlay resources, raising the abstraction level while reducing compile times significantly. We further demonstrate that this approach can even be used for run-time compilation of OpenCL kernels on the ARM processor of the embedded heterogeneous Zynq device.\",\n \"Title: Approximate ripple carry and carry lookahead adders — A comparative analysis\\nYear: 2017\\n\\nAbstract: Approximate ripple carry adders (RCAs) and carry lookahead adders (CLAs) are presented which are compared with accurate RCAs and CLAs for performing a 32-bit addition. The accurate and approximate RCAs and CLAs are implemented using a 32/28nm CMOS process. Approximations ranging from 4- to 20-bits are considered for the less significant adder bit positions. The simulation results show that approximate RCAs report reductions in the power-delay product (PDP) ranging from 19.5% to 82% than the accurate RCA for approximation sizes varying from 4- to 20-bits. Also, approximate CLAs report reductions in PDP ranging from 16.7% to 74.2% than the accurate CLA for approximation sizes varying from 4- to 20-bits. On average, for the approximation sizes considered, it is observed that approximate CLAs achieve a 46.5% reduction in PDP compared to the approximate RCAs. Hence, approximate CLAs are preferable over approximate RCAs for the low power implementation of approximate computer arithmetic.\",\n \"Title: Asynchronous early output section-carry based carry lookahead adder with alias carry logic\\nYear: 2017\\n\\nAbstract: A new asynchronous early output section-carry based carry lookahead adder (SCBCLA) with alias carry output logic is presented in this paper. To evaluate the proposed SCBCLA with alias carry logic and to make a comparison with other CLAs, a 32-bit addition operation is considered. Compared to the weak-indication SCBCLA with alias logic, the proposed early output SCBCLA with alias logic reports a 13% reduction in area without any increases in latency and power dissipation. On the other hand, in comparison with the early output recursive CLA (RCLA), the proposed early output SCBCLA with alias logic reports a 16% reduction in latency while occupying almost the same area and dissipating almost the same average power. All the asynchronous CLAs are quasi-delay-insensitive designs which incorporate the delay-insensitive dual-rail data encoding and adhere to the 4-phase return-to-zero handshaking. The adders were realized and the simulations were performed based on a 32/28nm CMOS process.\",\n \"Title: A novel two-stage modular multiplier based on racetrack memory for asymmetric cryptography\\nYear: 2017\\n\\nAbstract: Asymmetric cryptography algorithms such as RSA are widely used in applications such as blockchain technology and cloud computing to ensure the security and privacy of data. However, the encryption and decryption operations of asymmetric cryptography algorithms involve many computation-intensive multiplications, which require high memory bandwidth and involve large performance and resource overhead. Emerging non-volatile memory technologies such as racetrack memory are regarded to be promising for all levels of memory hierarchy to reduce the area and power overhead due to their high data density and nearly zero leakage. In this paper, we propose an efficient racetrack memory based in-memory design to accelerate the modular multiplication for asymmetric cryptography algorithms. A novel two-stage scalable modular multiplication algorithm is proposed to significantly improve the delay. An efficient architecture is further developed to reduce the number of required adders by half. Experimental results show that our proposed scheme improves the energy efficiency by 45.9%, the area efficiency by 93.6% and achieves 8x of throughput per area compared with the state-of-the-art CMOS-based implementation.\",\n \"Title: A Time-Multiplexed Fpga Overlay With Linear Interconnect\\nYear: 2018\\n\\nAbstract: Coarse-grained overlays improve FPGA design productivity by providing fast compilation and software like programmability. Soft processor based overlays with well-defined ISAs are attractive to application developers due to their ease of use. However, these overlays have significant FPGA resource overheads. Time multiplexed (TM) CGRA-like overlays represent an interesting alternative as they are able to change their behavior on a cycle by cycle basis while the compute kernel executes. This reduces the FPGA resource needed, but at the cost of a higher initiation interval (II) and hence reduced throughput.The fully flexible routing network of current CGRA-like overlays results in high FPGA resource usage. However, many application kernels are acyclic and can be implemented using a much simpler linear feed-forward routing network. This paper examines a DSP block based TM overlay with linear interconnect where the overlay architecture takes account of the application kernels' characteristics and the underlying FPGA architecture, so as to minimize the II and the FPGA resource usage. We examine a number of architectural extensions to the DSP block based functional unit to improve the II, throughput and latency. The results show an average 70% reduction in II, with corresponding improvements in throughput and latency.\",\n \"Title: A Self-Healing Redundancy Scheme for Mission/Safety-Critical Applications.\\nYear: 2018\\n\\nAbstract: In the nanoelectronics era, multiple faults or failures in circuits and systems deployed in mission- and safety-critical applications, such as space, aerospace, nuclear etc., are known to occur. To withstand these, higher order redundancy is suggested to be used selectively in the sensitive portions of a circuit or system. In this context, the distributed minority and majority voting based redundancy (DMMR) scheme was proposed as an alternative to the N-modular redundancy (NMR) scheme for the efficient implementation of higher order redundancy. However, the DMMR scheme is not self-healing. In this paper, we present a new self-healing redundancy (SHR) scheme that can inherently correct its internal faults or fail- ures without any external intervention, which makes it ideal for mission/safety-critical applications. To achieve the same degree of fault tolerance, the SHR scheme requires fewer function blocks than the NMR and DMMR schemes. We present the architectures of the proposed SHR scheme, discuss the system reliability, and provide the design metrics estimated for example SHR systems alongside the corresponding NMR and DMMR systems using a 32/28-nm CMOS technology. From the perspectives of fault tolerance, self-healing capability, and optimizations in the design metrics, the SHR scheme is preferable to the NMR and DMMR schemes.\",\n \"Title: A Hybrid Logic Block Architecture in FPGA for Holistic Efficiency.\\nYear: 2017\\n\\nAbstract: This brief presents a hybrid design of a configurable logic block (CLB) composed of look-up tables (LUTs) and universal logic gates (ULGs). A ULG is designed to realize holistic efficiency compared with the corresponding LUT. Previous designs with ULGs are either based on pure ULG or LUT-ULG complementary architecture, which incur a longer delay or double the area compared to the LUT-based design....\",\n \"Title: Approximate quasi-delay-insensitive asynchronous adders: Design and analysis\\nYear: 2017\\n\\nAbstract: Approximate computing is gaining increasing interest among the VLSI design community due to its potential for enabling low power, high speed, and less area while delivering acceptably correct computation results for many digital signal processing applications. In this context, this paper considers for the first time asynchronous quasi-delay-insensitive (QDI) realizations of approximate adders which are compared with some existing accurate asynchronous QDI adders based on a 32/28nm CMOS technology. The simulation results and analysis show that approximate asynchronous computing is preferable over accurate asynchronous computing when the accuracy may be traded-off to achieve optimizations in the design metrics.\",\n \"Title: Generalized Majority Voter Design Method For N-Modular Redundant Systems Used In Mission- And Safety-Critical Applications\\nYear: 2019\\n\\nAbstract: Mission- and safety-critical circuits and systems employ redundancy in their designs to overcome any faults or failures of constituent circuits and systems during the normal operation. In this aspect, the N-modular redundancy (NMR) is widely used. An NMR system is comprised of N identical systems, the corresponding outputs of which are majority voted to generate the system outputs. To perform majority voting, a majority voter is required, and the sizes of majority voters tend to vary depending on an NMR system. Majority voters corresponding to NMR systems are physically realized by enumerating the majority input clauses corresponding to an NMR system and then synthesizing the majority logic equation. The issue is that the number of majority input clauses corresponding to an NMR system is governed by a mathematical combination, the complexity of which increases substantially with increases in the level of redundancy. In this context, the design of a majority voter of any size corresponding to an NMR specification based on a new, generalized design approach is described. The proposed approach is inherently hierarchical and progressive since any NMR majority voter can be constructed from an (N - 2)MR majority voter along with additional logic corresponding to the two extra inputs. Further, the proposed approach paves the way for simultaneous production of the NMR system outputs corresponding to different degrees of redundancy, which is not intrinsic to the existing methods. This feature is additionally useful for any sharing of common logic with diverse degrees of redundancy in appropriate portions of an NMR implementation.\",\n \"Title: Asynchronous Early Output Block Carry Lookahead Adder with Improved Quality of Results.\\nYear: 2019\\n\\nAbstract: A new asynchronous early output, relative-timed block carry lookahead adder (BCLA) incorporating redundant carries is proposed. Compared to the best of existing semi-custom asynchronous carry lookahead adders (CLAs) employing delay-insensitive data encoding and following a 4-phase handshaking, the proposed BCLA with redundant carries achieves 14.9% reduction in cycle time and 12.3% reduction in area with no power penalty. A hybrid variant involving a ripple carry adder (RCA) in the least significant stages i.e. BCLA-RCA is also considered that achieves 15.2% reduction in cycle time and 11.2% reduction in area over the best of existing hybrid CLARCA variants without power penalty.\",\n \"Title: Majority and Minority Voted Redundancy for Safety-Critical Applications.\\nYear: 2019\\n\\nAbstract: A new majority and minority voted redundancy (MMR) scheme is proposed that can provide the same degree of fault tolerance as N-modular redundancy (NMR) but with fewer function units and a less sophisticated voting logic. Example NMR and MMR circuits were implemented using a 32/28nm CMOS process and compared. The results show that MMR circuits dissipate less power, occupy less area, and encounter less critical path delay than the corresponding NMR circuits while providing the same degree of fault tolerance. Hence the MMR is a promising alternative to the NMR to efficiently implement high levels of redundancy in safety-critical applications.\",\n \"Title: Coarse Grained FPGA Overlay for Rapid Just-In-Time Accelerator Compilation\\nYear: 2022\\n\\nAbstract: Coarse-grained FPGA overlays built around the runtime programmable DSP blocks in modern FPGAs can achieve high throughput and improved scalability compared to traditional overlays built without detailed consideration of FPGA architecture. These overlays can be mapped to using higher level compilers, achieving fast compilation, software-like programmability and run-time management, and high-level d...\",\n \"Title: Approximator: A Software Tool for Automatic Generation of Approximate Arithmetic Circuits\\nYear: 2022\\n\\nAbstract: Approximate arithmetic circuits are an attractive alternative to accurate arithmetic circuits because they have significantly reduced delay, area, and power, albeit at the cost of some loss in accuracy. By keeping errors due to approximate computation within acceptable limits, approximate arithmetic circuits can be used for various practical applications such as digital signal processing, digital filtering, low power graphics processing, neuromorphic computing, hardware realization of neural networks for artificial intelligence and machine learning etc. The degree of approximation that can be incorporated into an approximate arithmetic circuit tends to vary depending on the error resiliency of the target application. Given this, the manual coding of approximate arithmetic circuits corresponding to different degrees of approximation in a hardware description language (HDL) may be a cumbersome and a time-consuming process-more so when the circuit is big. Therefore, a software tool that can automatically generate approximate arithmetic circuits of any size corresponding to a desired accuracy would not only aid the design flow but also help to improve a designer's productivity by speeding up the circuit/system development. In this context, this paper presents 'Approximator', which is a software tool developed to automatically generate approximate arithmetic circuits based on a user's specification. Approximator can automatically generate Verilog HDL codes of approximate adders and multipliers of any size based on the novel approximate arithmetic circuit architectures proposed by us. The Verilog HDL codes output by Approximator can be used for synthesis in an FPGA or ASIC (standard cell based) design environment. Additionally, the tool can perform error and accuracy analyses of approximate arithmetic circuits. The salient features of the tool are illustrated through some example screenshots captured during different stages of the tool use. Approximator has been made open-access on GitHub for the benefit of the research community, and the tool documentation is provided for the user's reference.\",\n \"Title: An Approximate Adder with Reduced Error and Optimized Design Metrics\\nYear: 2021\\n\\nAbstract: We present a new approximate adder with reduced error and optimized design metrics. The proposed approximate adder is derived by modifying an existing approximate adder HERLOA and is called modified HERLOA or M-HERLOA in short. We considered a systematic modification of HERLOA to derive an optimum M-HERLOA for a digital image processing application. We calculated popular error parameters such as mean absolute error (also called mean error distance) and root mean square error of the approximate adders. We estimated the design metrics of accurate and approximate adders based on FPGA and ASIC (standard cell based) implementations. We compare the performance of accurate adder and approximate adders for an image processing application by estimating the peak signal to noise ratio and structural similarity index metric. We find that the proposed M-HERLOA reconstructs a digital image that is similar to the image reconstructed using the accurate adder. This is achieved with M-HERLOA simultaneously enabling following optimizations in design metrics compared to the accurate adder for a 32 bit addition: (i) 9.5% reduction in minimum clock period, 9.1% reduction in total on-chip power consumption, and 7 LUTs and 18 flip-flops less for a FPGA implementation, and (ii) 18% reduction in critical path delay, 26.7% reduction in average power dissipation, and 23.1% reduction in silicon area for an ASIC type implementation.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":80,"string":"80"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":268,"string":"268"}}},{"rowIdx":269,"cells":{"question_id":{"kind":"string","value":"Hans Uszkoreit"},"question":{"kind":"string","value":"Generate an abstract for the title \"Capturing paradigmatic and syntagmatic lexical relations: towards accurate Chinese part-of-speech tagging\" using the following items: Chinese POS tagging, Structural linguistics, Paradigmatic relations, Syntagmatic relations, Error reduction."},"answer":{"kind":"string","value":"From the perspective of structural linguistics, we explore paradigmatic and syntagmatic lexical relations for Chinese POS tagging, an important and challenging task for Chinese language processing. Paradigmatic lexical relations are explicitly captured by word clustering on large-scale unlabeled data and are used to design new features to enhance a discriminative tagger. Syntagmatic lexical relations are implicitly captured by constituent parsing and are utilized via system combination. Experiments on the Penn Chinese Treebank demonstrate the importance of both paradigmatic and syntagmatic relations. Our linguistically motivated approaches yield a relative error reduction of 18% in total over a state-of-the-art baseline."},"correct_answer":{"kind":"string","value":"From the perspective of structural linguistics, we explore paradigmatic and syntagmatic lexical relations for Chinese POS tagging, an important and challenging task for Chinese language processing. Paradigmatic lexical relations are explicitly captured by word clustering on large-scale unlabeled data and are used to design new features to enhance a discriminative tagger. Syntagmatic lexical relations are implicitly captured by constituent parsing and are utilized via system combination. Experiments on the Penn Chinese Treebank demonstrate the importance of both paradigmatic and syntagmatic relations. Our linguistically motivated approaches yield a relative error reduction of 18% in total over a state-of-the-art baseline."},"documents":{"kind":"list like","value":["Title: Categorial Unification Grammars\nYear: 1986\n\nAbstract: Categorial unification grammars (CUGs) embody the essential properties of both unification and categorial grammar formalisms. Their efficient and uniform way of encoding linguistic knowledge in well-understood and widely used representations makes them attractive for computational applications and for linguistic research.In this paper, the basic concepts of CUGs and simple examples of their application will be presented. It will be argued that the strategies and potentials of CUGs justify their further exploration in the wider context of research on unification grammars. Approaches to selected linguistic phenomena such as long-distance dependencies, adjuncts, word order, and extraposition are discussed.","Title: LT World: Ontology and Reference Information Portal\nYear: 2010\n\nAbstract: LT World (www.lt-world.org) is an ontology-driven web portal aimed at serving the global language technology community. Ontology-driven means, that the system is driven by an ontological schema to manage the research information and knowledge life-cycles: identify relevant concepts of information, structure and formalize them, assign relationships, functions and views, add states and rules, modify them. For modelling such a complex structure, we employ (i) concepts from the research domain, such as person, organisation, project, tool, data, patent, news, event (ii) concepts from the LT domain, such as technology and resource (iii) concepts from closely related domains, such as language, linguistics, and mathematics. Whereas the research entities represent the general context, that is, a research environment as such, the LT entities define the information and knowledge space of the field, enhanced by entities from closely related areas. By managing information holistically - that is, within a research context - its inherent semantics becomes much more transparent. This paper introduces LT World as a reference information portal through ontological eyes: its content, its system, its method for maintaining knowledge-rich items, its ontology as an asset.","Title: Annotating Relation Mentions in Tabloid Press.\nYear: 2014\n\nAbstract: This paper presents a new resource for the training and evaluation needed by relation extraction experiments. The corpus consists of annotations of mentions for three semantic relations: marriage, parent-child, siblings, selected from the domain of biographic facts about persons and their social relationships. The corpus contains more than one hundred news articles from Tabloid Press. In the current corpus, we only consider the relation mentions occurring in the individual sentences. We provide multi-level annotations which specify the marked facts from relation, argument, entity, down to the token level, thus allowing for detailed analysis of linguistic phenomena and their interactions. A generic markup tool Recon developed at the DFKI LT lab has been utilised for the annotation task. The corpus has been annotated by two human experts, supported by additional conflict resolution conducted by a third expert. As shown in the evaluation, the annotation is of high quality as proved by the stated inter-annotator agreements both on sentence level and on relation-mention level. The current corpus is already in active use in our research for evaluation of the relation extraction performance of our automatically learned extraction patterns.","Title: Formal constraints on metarules\nYear: 1983\n\nAbstract: Metagrammatical formalisms that combine context-free phrase structure rules and metarules (MPS grammars) allow concise statement of generalizations about the syntax of natural languages. Unconstrained MPS grammars, unfortunately, are not computationally \"safe.\" We evaluate several proposals for constraining them, basing our assessment on computational tractability and explanatory adequacy. We show that none of them satisfies both criteria, and suggest new directions for research on alternative metagrammatical formalisms.","Title: Identifying semantic relations between named entities from chinese texts\nYear: 2005\n\nAbstract: COLLATE is a project dedicated to building up a German authority center for language technology in Saarbrücken. Under this project, a computational model with three-stage pipeline architecture for Chinese information extraction has been proposed. In this paper, we concentrate on the presentation for the third stage, viz., the identification of named entity relations (NERs). A learning and identification approach for NERs called positive and negative case-based learning and identification is described in detail. It pursues the improvement of the identification performance for NERs through simultaneously learning two opposite cases, automatically selecting effective multi-level linguistic features for each NER and non-NER, and optimally achieving an identification tradeoff etc. The experimental results have shown that the overall average recall, precision, and F-measure for 14 NERs are 78.50%, 63.92% and 70.46% respectively. In addition, the above F-measure has been enhanced from 63.61% to 70.46% due to adoption of both positive and negative cases.","Title: Hybrid Learning of Dependency Structures from Heterogeneous Linguistic Resources.\nYear: 2008\n\nAbstract: In this paper we present our syntactic and semantic dependency parsing system participated in both closed and open competitions of the CoNLL 2008 Shared Task. By combining the outcome of two state-of-the-art syntactic dependency parsers, we achieved high accuracy in syntactic dependencies (87.32%). With MRSes from grammar-based HPSG parsers, we achieved significant performance improvement on semantic role labeling (from 71.31% to 71.89%), especially in the out-domain evaluation (from 60.16% to 62.11%).","Title: Gossip Galore: A Conversational Web Agent for Collecting and Sharing Pop Trivia\nYear: 2009\n\nAbstract: This paper presents a novel approach to a self-learning agent who collects and learns new knowledge from the web and exchanges her knowledge via dialogues with the users. The application domain is gossip about celebrities in the music world. The agent can inform herself and update the acquired knowledge by observing the web. Fans of musicians can ask for gossip information about stars, bands or people and groups related to them. This agent is built on top of information extraction, web mining, question answering and dialogue system technologies. The minimally supervised machine learning method for relation extraction gives the agent the capability to learn and update knowledge constantly from the web. The extracted relations are structured and linked with each other. Data mining is applied to the learned data to induce the social network among the artists and related people. The knowledge-intensive question answering technology enhanced by domain-specific inference and active memory allows the agent to have vivid and interactive conversations with users by utilizing natural language processing. Users can freely formulate their questions within the gossip data domain and access the answers in different ways: textual response, graph-based visualization of the related concepts and speech output.","Title: Dependency graphs as a generic interface between parsers and relation extraction rule learning\nYear: 2011\n\nAbstract: In this paper, we propose to use dependency graphs rather than trees as the interface between a parser and the rule acquisition module of a relation extraction (RE) system. Dependency graphs are much more expressive than trees and can easily be adapted to the output representations of various parsers, in particular those with richer semantics. Our approach is built on top of an existing minimally supervised machine learning system for relation extraction. We extend its original tree-based interface to a graph-based representation. In our experiments, we make use of two different dependency parsers and a deep HPSG parser. As expected, switching to a graph representation for the parsers outputting dependency trees does not have any impact on the RE results. But using the graph-based representation for the extraction with deep HPSG analyses improves both recall and f-score of the RE and enables the system to extract more relation instances of higher arity. Furthermore, we also compare the performance among these parsers with respect to their contribution to the RE task. In general, the robust dependency parsers are good in recall. However, the fine-grained deep syntactic parsing wins when it comes to precision.","Title: A system for supporting cross-lingual information retrieval\nYear: 2000\n\nAbstract: In this paper, we present the system MULINEX, a fully implemented system which supports cross-lingual search of the WWW. Users can formulate, expand and disambiguate queries, filter the search results and read the retrieved documents by using their native language alone. This multilingual functionality is achieved by the use of dictionary-based query translation, multilingual document categorisation and automatic translation of summaries and documents. The system supports French, German and English and has been installed and tested in the online services of two European internet content and service provider companies. This paper focuses on the techniques and algorithms used in the MULINEX system, explaining how each component works and how it contributes to the overall functionality of the integrated system. The primary system functionalities are outlined from the user perspective, followed by a description of the document database used in the system. The technologies and linguistic resources used in the various system components are then described in detail.","Title: Combining multi-engine translations with Moses\nYear: 2009\n\nAbstract: We present a simple method for generating translations with the Moses toolkit (Koehn et al., 2007) from existing hypotheses produced by other translation engines. As the structures underlying these translation engines are not known, an evaluation-based strategy is applied to select systems for combination. The experiments show promising improvements in terms of BLEU.","Title: An integrated architecture for shallow and deep processing\nYear: 2002\n\nAbstract: We present an architecture for the integration of shallow and deep NLP components which is aimed at flexible combination of different language technologies for a range of practical current and future applications. In particular, we describe the integration of a high-level HPSG parsing system with different high-performance shallow components, ranging from named entity recognition to chunk parsing and shallow clause recognition. The NLP components enrich a representation of natural language text with layers of new XML meta-information using a single shared data structure, called the text chart. We describe details of the integration methods, and show how information extraction and language checking applications for realworld German text benefit from a deep grammatical analysis.","Title: Language Resources and Annotation Tools for Cross-Sentence Relation Extraction.\nYear: 2014\n\nAbstract: In this paper, we present a novel combination of two types of language resources dedicated to the detection of relevant relations (RE) such as events or facts across sentence boundaries. One of the two resources is the sar-graph, which aggregates for each target relation ten thousands of linguistic patterns of semantically associated relations that signal instances of the target relation (Uszkoreit and Xu, 2013). These have been learned from the Web by intra-sentence pattern extraction (Krause et al., 2012) and after semantic filtering and enriching have been automatically combined into a single graph. The other resource is cockrACE, a specially annotated corpus for the training and evaluation of cross-sentence RE. By employing our powerful annotation tool Recon, annotators mark selected entities and relations (including events), coreference relations among these entities and events, and also terms that are semantically related to the relevant relations and events. This paper describes how the two resources are created and how they complement each other.","Title: A Linguistically Interpreted Corpus of German Newspaper Text\nYear: 1998\n\nAbstract: In this paper, we report on the development of an annotation scheme and\nannotation tools for unrestricted German text. Our representation format is\nbased on argument structure, but also permits the extraction of other kinds of\nrepresentations. We discuss several methodological issues and the analysis of\nsome phenomena. Additional focus is on the tools developed in our project and\ntheir applications.","Title: From feature bundles to abstract data types: new directions in the representation and processing of linguistic knowledge\nYear: 1988\n\nAbstract: Without Abstract","Title: Large-Scale learning of relation-extraction rules with distant supervision from the web\nYear: 2012\n\nAbstract: We present a large-scale relation extraction (RE) system which learns grammar-based RE rules from the Web by utilizing large numbers of relation instances as seed. Our goal is to obtain rule sets large enough to cover the actual range of linguistic variation, thus tackling the long-tail problem of real-world applications. A variant of distant supervision learns several relations in parallel, enabling a new method of rule filtering. The system detects both binary and n-ary relations. We target 39 relations from Freebase, for which 3M sentences extracted from 20M web pages serve as the basis for learning an average of 40K distinctive rules per relation. Employing an efficient dependency parser, the average run time for each relation is only 19 hours. We compare these rules with ones learned from local corpora of different sizes and demonstrate that the Web is indeed needed for a good coverage of linguistic variation.","Title: Chinese named entity and relation identification system\nYear: 2006\n\nAbstract: In this interactive presentation, a Chinese named entity and relation identification system is demonstrated. The domain-specific system has a three-stage pipeline architecture which includes word segmentation and part-of-speech (POS) tagging, named entity recognition, and named entity relation identitfication. The experimental results have shown that the average F-measure for word segmentation and POS tagging after correcting errors achieves 92.86 and 90.01 separately. Moreover, the overall average F-measure for 6 kinds of name entities and 14 kinds of named entity relations is 83.08% and 70.46% respectively.","Title: Using syntactic and semantic based relations for dialogue act recognition\nYear: 2010\n\nAbstract: This paper presents a novel approach to dialogue act recognition employing multilevel information features. In addition to features such as context information and words in the utterances, the recognition task utilizes syntactic and semantic relations acquired by information extraction methods. These features are utilized by a Bayesian network classifier for our dialogue act recognition. The evaluation results show a clear improvement from the accuracy of the baseline (only with word features) with 61.9% to an accuracy of 67.4% achieved by the extended feature set.","Title: Handling linear precedence constraints by unification\nYear: 1992\n\nAbstract: Linear precedence (LP) rules are widley used for stating word order principles. They have been adopted as constraints by HPSG but no encoding in the formalism has been provided. Since they only order siblings, they are not quite adequate, at least not for German. We propose a notion of LP constraints that applies to linguistically motivated branching domains such as head domains. We show a type-based encoding in an HPSG-style formalism that supports processing. The encoding can be achieved by a compilation step.","Title: The Strategic Impact of META-NET on the Regional, National and International Level.\nYear: 2014\n\nAbstract: This article provides an overview of the dissemination work carried out in META-NET from 2010 until 2015; we describe its impact on the regional, national and international level, mainly with regard to politics and the funding situation for LT topics. The article documents the initiativeu0027s work throughout Europe in order to boost progress and innovation in our field.","Title: An ontology of systematic relations for a shared grammar of Slavic\nYear: 2000\n\nAbstract: Sharing portions of grammars across languages greatly reduces the costs of multilingual grammar engineering. Related languages share a much wider range of linguistic information than typically assumed in standard multilingual grammar architectures. Taking grammatical relatedness seriously, we are particularly interested in designing linguistically motivated grammatical resources for Slavic languages to be used in applied and theoretical computational linguistics. In order to gain the perspective of a language-family oriented grammar design, we consider an array of systematic relations that can hold between syntactical units. While the categorisation of primitive linguistic entities tends to be language-specific or even construction-specific, the relations holding between them allow various degrees of abstraction. On the basis of Slavic data, we show how a domain ontology conceptualising morpho-syntactic \"building blocks\" can serve as a basis of a shared grammar of Slavic.","Title: Conversational agents in a virtual world\nYear: 2011\n\nAbstract: This paper presents a system that builds on theoretical and experimental insights from linguistic pragmatics, uses novel techniques from computational linguistics and combines them with robust baseline technologies to provide intelligent Non Player Characters (NPCs), which naturally act and talk in a virtual world. Current NPCs still lack the necessary linguistic knowledge and methods to apply them to the numerous conversational application areas in virtual worlds. The system presented in this paper manages two NPCs, a barkeeper and a furniture sales agent, which highly depend on conversational abilities.","Title: Challenges and solutions of multilingual and translingual information service systems\nYear: 2007\n\nAbstract: In this paper, we present a survey of challenges and solutions of multilingual and translingual information service systems. In contrast to the computational linguistics literature on such systems, we are approaching the theme here from an HCI perspective. We will argue for a strategy that reduces reliance on automatic free-text translation, language input and classical information retrieval while not giving up these less reliable technologies altogether. We will also opt for a close situation-driven integration of information and communication functionalities. The described solutions have been incorporated into a novel mobile combined information and communication system for foreign tourists that has been tested under realistic conditions by users from several countries. The system is developed by the German-Chinese cooperation project COMPASS20081, a research action within the Digital Olympics framework.","Title: Learning relation extraction grammars with minimal human intervention: strategy, results, insights and plans\nYear: 2011\n\nAbstract: The paper describes the operation and evolution of a linguistically oriented framework for the minimally supervised learning of relation extraction grammars from textual data. Cornerstones of the approach are the acquisition of extraction rules from parsing results, the utilization of closed-world semantic seeds and a filtering of rules and instances by confidence estimation. By a systematic walk through the major challenges for this approach the obtained results and insights are summarized. Open problems are addressed and strategies for solving these are outlined.","Title: A Seed-driven Bottom-up Machine Learning Framework for Extracting Relations of Various Complexity\nYear: 2007\n\nAbstract: A minimally supervised machine learning framework is described for extracting rela- tions of various complexity. Bootstrapping starts from a small set of n-ary relation in- stances as \"seeds\", in order to automati- cally learn pattern rules from parsed data, which then can extract new instances of the relation and its projections. We propose a novel rule representation enabling the composition of n-ary relation rules on top of the rules for projections of the relation. The compositional approach to rule con- struction is supported by a bottom-up pat- tern extraction method. In comparison to other automatic approaches, our rules can- not only localize relation arguments but also assign their exact target argument roles. The method is evaluated in two tasks: the extraction of Nobel Prize awards and management succession events. Perfor- mance for the new Nobel Prize task is strong. For the management succession task the results compare favorably with those of existing pattern acquisition ap- proaches.","Title: Information Extraction from German Patient Records via Hybrid Parsing and Relation Extraction Strategies.\nYear: 2014\n\nAbstract: In this paper, we report on first attempts and findings to analyzing German patient records, using a hybrid parsing architecture and a combination of two relation extraction strategies. On a practical level, we are interested in the extraction of concepts and relations among those concepts, a necessary cornerstone for building medical information systems. The parsing pipeline consists of a morphological analyzer, a robust chunk parser adapted to Latin phrases used in medical diagnosis, a repair rule stage, and a probabilistic context-free parser that respects the output from the chunker. The relation extraction stage is a combination of two systems: SProUT, a shallow processor which uses hand-written rules to discover relation instances from local text units and DARE which extracts relation instances from complete sentences, using rules that are learned in a bootstrapping process, starting with semantic seeds. Two small experiments have been carried out for the parsing pipeline and the relation extraction stage.","Title: COMPASS2008: the smart dining service\nYear: 2005\n\nAbstract: The Compass2008 project is a sino-german cooperation, aiming at integrating advanced information technologies to create a high-tech information system that helps visitors to access location-sensitive information services during the 2008 Olympic Games in their preferred language, offering a variety of service-adaptive modalities available on the mobile devices. In this paper, we demonstrate one of the COMPASS2008 services, the Smart Dining Service, to showcase the new interaction concepts between multimodality, multilingual and location-sensitive information search.","Title: Parse reranking for domain-adaptative relation extraction.\nYear: 2014\n\nAbstract: The article demonstrates how generic parsers in a minimally supervised information extraction framework can be adapted to a given task and domain for relation extraction (RE). For the experiments, two parsers that deliver n-best readings are included: (1) a generic deep-linguistic parser (PET) with a largely hand-crafted head-driven phrase structure grammar for English (ERG); (2) a generic statist...","Title: A flexible graph-unification formalism and its application to natural-language processing\nYear: 1988\n\nAbstract: A graph-unification-based representation language is described that was developed as the grammar formalism for the LILOG research project at IBM Germany. The Stuttgart Unification Formalism (STUF) differs from its predecessors in its higher flexibility and its algebraic structure. It is well suited for the implementation of rather different linguistic approaches, but is currently employed mainly in the development of Categorial Unification Grammars with a lexicalized compositional semantics. Examples from the syntactic and semantic processing of natural language are used to illustrate the virtues of the formalism and of our lexicalist approach to linguistic analysis.","Title: DISCO - An HPSG-based NLP System and its Application for Appointment Scheduling (Project Note).\nYear: 1994\n\nAbstract: The natural language system DISCO is described. It combines o a powerful and\nflexible grammar development system; o linguistic competence for German\nincluding morphology, syntax and semantics; o new methods for linguistic\nperformance modelling on the basis of high-level competence grammars; o new\nmethods for modelling multi-agent dialogue competence; o an interesting sample\napplication for appointment scheduling and calendar management.","Title: Question Answering Biographic Information and Social Network Powered by the Semantic Web\nYear: 2010\n\nAbstract: After several years of development, the vision of the Semantic Web is gradually becoming reality. Large data repositories have been created and offer semantic information in a machine-processable form for various domains. Semantic Web data can be published on the Web, gathered automatically, and reasoned about. All these developments open interesting perspectives for building a new class of domain-specific, broad-coverage information systems that overcome a long-standing bottleneck of AI systems, the notoriously incomplete knowledge base. We present a system that shows how the wealth of information in the Semantic Web can be interfaced with humans once again, using natural language for querying and answering rather than technical formalisms. Whereas current Question Answering systems typically select snippets from Web documents retrieved by a search engine, we utilize Semantic Web data, which allows us to provide natural-language answers that are tailored to the current dialog context. Furthermore, we show how to use natural language processing technologies to acquire new data and enrich existing data in a Semantic Web framework. Our system has acquired a rich biographic data resource by combining existing Semantic Web resources, which are discovered from semi-structured textual data in Web pages, with information extracted from free natural language texts.","Title: GETESS - Searching the Web Exploiting German Texts\nYear: 1999\n\nAbstract: We present an intelligent information agent that uses semantic methods and natural language processing capabilites in order to gather tourist information from theWWWand present it to the human user in an intuitive, user-friendly way. Thereby, the information agent is designed such that as background knowledge and linguistic coverage increase, its benefits improve, while it guarantees state-of-the-art information and database retrieval capabilities as its bottom line.","Title: A framework for processing partially free word order\nYear: 1983\n\nAbstract: The partially free word order in German belongs to the class of phenomena in natural language that require a close interaction between syntax and pragmatics. Several competing principles, which are based on syntactic and on discourse information, determine the linear order of noun phrases. A solution to problems of this sort is a prerequisite for high-quality language generation. The linguistic framework of Generalized Phrase Structure Grammar offers tools for dealing with word order variation. Some slight modifications to the framework allow for an analysis of the German data that incorporates just the right degree of interaction between syntactic and pragmatic components and that can account for conflicting ordering statements.","Title: Translation combination using factored word substitution\nYear: 2009\n\nAbstract: We present a word substitution approach to combine the output of different machine translation systems. Using part of speech information, candidate words are determined among possible translation options, which in turn are estimated through a pre-computed word alignment. Automatic substitution is guided by several decision factors, including part of speech, local context, and language model probabilities. The combination of these factors is defined after careful manual analysis of their respective impact. The approach is tested for the language pair German-English, however the general technique itself is language independent.","Title: An annotation scheme for free word order languages\nYear: 1997\n\nAbstract: We describe an annotation scheme and a tool developed for creating linguistically annotated corpora for non-configurational languages. Since the requirements for such a formalism differ from those posited for configurational languages, several features have been added, influencing the architecture of the scheme. The resulting scheme reflects a stratificational notion of language, and makes only minimal assumptions about the interrelation of the particular representational strata.","Title: Software for annotating argument structure\nYear: 1997\n\nAbstract: We present a tool developed for annotating corpora with argument structure representations. The presentation focuses on the architecture of the annotation scheme and a number of techniques for increasing the efficiency and accuracy of annotation. Among others, we show how the assignment of grammatical functions can be automatised using standard part-of-speech tagging methods.","Title: A successful field test of a mobile and multilingual information service system COMPASS2008\nYear: 2007\n\nAbstract: We will describe a field test and its evaluation of a truly novel type of mobile computer programs that will assist foreign tourists in their communication with Chinese people. The software is an electronic phrase book and a translation aid but at the same time a powerful multilingual information system connected to numerous services via the Internet. It effectively helps visitors to navigate through the streets, temples and shopping centres of the Beijing megalopolis. It was developed in the German-Chinese project COMPASS 2008, a research action within the Digital Olympics framework. The subjects of the field test were fifteen tourists from seven countries. The test concentrated on usability and acceptance. The applied methodology adapts recognized standards and widely accepted best practice to the specific application type.","Title: Talking NPCs in a virtual game world\nYear: 2010\n\nAbstract: This paper describes the KomParse system, a natural-language dialog system in the three-dimensional virtual world Twinity. In order to fulfill the various communication demands between nonplayer characters (NPCs) and users in such an online virtual world, the system realizes a flexible and hybrid approach combining knowledge-intensive domain-specific question answering, task-specific and domain-specific dialog with robust chatbot-like chitchat.","Title: YAGO-QA: Answering Questions by Structured Knowledge Queries\nYear: 2011\n\nAbstract: We present a natural-language question-answering system that gives access to the accumulated knowledge of one of the largest community projects on the Web 芒聙\" Wikipedia 芒聙\" via an automatically acquired structured knowledge base. Key to building such a system is to establish mappings from natural language expressions to semantic representations. We propose to acquire these mappings by data-driven methods 芒聙\" corpus harvesting and paraphrasing 芒聙\" and present a preliminary empirical study that demonstrates the viability of our method.","Title: Further experiments with shallow hybrid MT systems\nYear: 2010\n\nAbstract: We describe our hybrid machine translation system which has been developed for and used in the WMT10 shared task. We compute translations from a rule-based MT system and combine the resulting translation \"templates\" with partial phrases from a state-of-the-art phrase-based, statistical MT engine. Phrase substitution is guided by several decision factors, a continuation of previous work within our group. For the shared task, we have computed translations for six language pairs including English, German, French and Spanish. Our experiments have shown that our shallow substitution approach can effectively improve the translation result from the RBMT system; however it has also become clear that a deeper integration is needed to further improve translation quality.","Title: DFKI hybrid machine translation system for WMT 2011: on the integration of SMT and RBMT\nYear: 2011\n\nAbstract: We present the DFKI hybrid translation system at the WMT workshop 2011. Three SMT and two RBMT systems are combined at the level of the final translation output. The translation results show that our hybrid system significantly outperformed individual systems by exploring strengths of both rule-based and statistical translations.","Title: Strategies for adding control information to declarative grammars\nYear: 1991\n\nAbstract: Strategies are proposed for combining different kinds of constraints in declarative grammars with a detachable layer of control information. The added control information is the basis for parametrized dynamically controlled linguistic deduction, a form of linguistic processing that permits the implementation of plausible linguistic performance models without giving up the declarative formulation of linguistic competence. The information can be used by the linguistic processor for ordering the sequence in which conjuncts and disjuncts are processed, for mixing depth-first and breadth-first search, for cutting off undesired derivations, and for constraint-relaxation.","Title: Task Driven Coreference Resolution for Relation Extraction\nYear: 2008\n\nAbstract: This paper presents the extension of an existing mimimally supervised rule acquisition method for relation extraction by coreference resolution (CR). To this end, a novel approach to CR was designed and tested. In comparison to state-of-the-art methods for CR, our strategy is driven by the target semantic relation and utilizes domain-specific ontological and lexical knowledge in addition to the learned relation extraction rules. An empirical investigation reveals that newswire texts in our selected domains contain more coreferring noun phrases than prononimal coreferences. This means that existing methods for CR would not suffice and a semantic approach is needed. Our experiments show that the utilization of domain knowledge can boost CR. In our approach, the tasks of relation extraction and CR support each other. On the one hand, reference resolution is needed for the detection of arguments of the target relation. On the other hand, domain modelling for the IE task is used for semantic classification of the referring nouns. Moreover, the application of the learned relation extraction rules often narrows down the number of candidates for CR. With respect to the minimally supervised learning of relation extraction grammars, we design and evaluate two integration strategies: (i) resolution after the complete pattern acquisition process and (ii) resolution embedded in the iterations of the learning process. The evaluation helps us to gain and substantiate a relevant insight: CR effectively improves recall in both strategies but it can hurt the precision because of its error spreading potential.","Title: Minimally supervised domain-adaptive parse reranking for relation extraction\nYear: 2011\n\nAbstract: The paper demonstrates how the generic parser of a minimally supervised information extraction framework can be adapted to a given task and domain for relation extraction (RE). For the experiments a generic deep-linguistic parser was employed that works with a largely hand-crafted head-driven phrase structure grammar (HPSG) for English. The output of this parser is a list of n best parses selected and ranked by a MaxEnt parse-ranking component, which had been trained on a more or less generic HPSG treebank. It will be shown how the estimated confidence of RE rules learned from the n best parses can be exploited for parse reranking. The acquired reranking model improves the performance of RE in both training and test phases with the new first parses. The obtained significant boost of recall does not come from an overall gain in parsing performance but from an application-driven selection of parses that are best suited for the RE task. Since the readings best suited for successful rule extraction and instance extraction are often not the readings favored by a regular parser evaluation, generic parsing accuracy actually decreases. The novel method for task-specific parse reranking does not require any annotated data beyond the semantic seed, which is needed anyway for the RE task.","Title: Determining the Origin and Structure of Person Names\nYear: 2010\n\nAbstract: This paper presents a novel system HENNA (Hybrid Person Name Analyzer) for identifying language origin and analyzing linguistic structures of person names. We conduct ME-based classification methods for the language origin identification and achieve very promising performance. We will show that word-internal character sequences provide surprisingly strong evidence for predicting the language origin of person names. Our approach is context-, language-and domain-independent and can thus be easily adapted to person names in or from other languages. Furthermore, we provide a novel strategy to handle origin ambiguities or multiple origins in a name. HENNA also provides a person name parser for the analysis of linguistic and knowledge structures of person names. All the knowledge about a person name in HENNA is modelled in a person-name ontology, including relationships between language origins, linguistic features and grammars of person names of a specific language and interpretation of name elements. The approaches presented here are useful extensions of the named entity recognition task.","Title: The taraXÜ corpus of human-annotated machine translations.\nYear: 2014\n\nAbstract: Human translators are the key to evaluating machine translation (MT) quality and also to addressing the so far unanswered question when and how to use MT in professional translation workflows. This paper describes the corpus developed as a result of a detailed large scale human evaluation consisting of three tightly connected tasks: ranking, error classification and post-editing.","Title: Extracting and Querying Relations in Scientific Papers\nYear: 2008\n\nAbstract: High-precision linguistic and semantic analysis of scientific texts is an emerging research area. We describe methods and an application for extracting interesting factual relations from scientific texts in computational linguistics and language technology. We use a hybrid NLP architecture with shallow preprocessing for increased robustness and domain-specific, ontology-based named entity recognition, followed by a deep HPSG parser running the English Resource Grammar (ERG). The extracted relations in the MRS (minimal recursion semantics) format are simplified and generalized using WordNet. The resulting `quriples' are stored in a database from where they can be retrieved by relation-based search. The query interface is embedded in a web browser-based application we call the Scientist's Workbench. It supports researchers in editing and online-searching scientific papers.","Title: Evaluation Resources for Concept-based Cross-Lingual Information Retrieval in the Medical Domain\nYear: 2004\n\nAbstract: The paper describes evaluation resources for concept-based, cross-lingual information retrieval in the medical domain. All resources were constructed in the context of the MuchMore project and are freely available through the project website. Available resources include: a bilingual, parallel document collection of German and English medical scientific abstracts, a set of queries and corresponding relevance assessments, two manually disambiguated test sets for semantic annotation (sense disambiguation), two evaluation lists for German morphological decomposition of medical terms.","Title: COMPASS2008: multimodal, multilingual and crosslingual interaction for mobile tourist guide applications\nYear: 2005\n\nAbstract: COMPASS2008 is a general service platform developed to be utilized as the tourist and city explorers assistant within the information services for the Beijing Olympic Games 2008. The main goals of COMPASS2008 are to help foreigners to overcome language barriers in Beijing and assist them in finding information anywhere and anytime they need it. Novel strategies have been developed to exploit the interaction of multimodality, multilinguality and cross-linguality for intelligent information service access and information presentation via mobile devices.","Title: Sprinter: Language Technologies for Interactive and Multimedia Language Learning.\nYear: 2014\n\nAbstract: Modern language learning courses are no longer exclusively based on books or face-to-face lectures. More and more lessons make use of multimedia and personalized learning methods. Many of these are based on e-learning solutions. Learning via the Internet provides 7/24 services that require sizeable human resources. Therefore we witness a growing economic pressure to employ computer-assisted methods for improving language learning in quality, efficiency and scalability. In this paper, we will address three applications of language technologies for language learning: 1) Methods and strategies for pronunciation training in second language learning, e.g., multimodal feedback via visualization of sound features, speech verification and prosody transplantation; 2) Dialogue-based language learning games; 3) Application of parsing and generation technologies to the automatic generation of paraphrases for the semi-automatic production of learning material.","Title: Semantic Rule Filtering for Web-Scale Relation Extraction\nYear: 2013\n\nAbstract: Web-scale relation extraction is a means for building and extending large repositories of formalized knowledge. This type of automated knowledge building requires a decent level of precision, which is hard to achieve with automatically acquired rule sets learned from unlabeled data by means of distant or minimal supervision. This paper shows how precision of relation extraction can be considerably improved by employing a wide-coverage, general-purpose lexical semantic network, i.e., BabelNet, for effective semantic rule filtering. We apply Word Sense Disambiguation to the content words of the automatically extracted rules. As a result a set of relation-specific relevant concepts is obtained, and each of these concepts is then used to represent the structured semantics of the corresponding relation. The resulting relation-specific subgraphs of BabelNet are used as semantic filters for estimating the adequacy of the extracted rules. For the seven semantic relations tested here, the semantic filter consistently yields a higher precision at any relative recall value in the high-recall range.","Title: Evaluation of the KomParse Conversational Non-Player Characters in a Commercial Virtual World.\nYear: 2012\n\nAbstract: The paper describes the evaluation of the KomParse system. KomParse is a dialogue system embedded in a 3-D massive multiplayer online game, allowing conversations between non player characters (NPCs) and game users. In a field test with game users, the system was evaluated with respect to acceptability and usability of the overall system as well as task completion, dialogue control and efficiency of three conversational tasks. Furthermore, subjective feedback has been collected for evaluating the single communication components of the system such as natural language understanding. The results are very satisfying and promising. In general, both the usability and acceptability tests show that the tested NPC is useful and well-accepted by the users. Even if the NPC does not always understand the users well and expresses things unexpected, he could still provide appropriate responses to help users to solve their problems or entertain them.","Title: Building a Lexical Sports Ontology for Chinese IE Using Reusable Strategy\nYear: 2007\n\nAbstract: In this paper, we propose a strategy to construct a lexical ontology used for Chinese named entities (NEs) and NE relations (NERs) identification. The lexical information from HowNet (reusable information) and semantic constraints (added information) are semi- automatically integrated into our lexical ontology. In the ontology, addition to the relationships of the concepts in the taxonomy, the non-taxonomic relationships between the concepts have been also built through semantic constraints. The testing results for Chinese named entity and relation identification system have shown that the total average F-measure for six types of NEs and fourteen types of NERs is 83.08% and 70.46% respectively. Therefore, this lexical ontology used for Chinese NE and NER identification is reasonable and effective.","Title: Analysis and improvement of minimally supervised machine learning for relation extraction\nYear: 2009\n\nAbstract: The main contribution of this paper is a systematic analysis of a minimally supervised machine learning method for relation extraction grammars. The method is based on a bootstrapping approach in which the bootstrapping is triggered by semantic seeds. The starting point of our analysis is the pattern-learning graph which is a subgraph of the bipartite graph representing all connections between linguistic patterns and relation instances exhibited by the data. It is shown that the performance of such general learning framework for actual tasks is dependent on certain properties of the data and on the selection of seeds. Several experiments have been conducted to gain explanatory insights into the interaction of these two factors. From the investigation of more effective seeds and benevolent data we understand how to improve the learning in less fortunate configurations. A relation extraction method only based on positive examples cannot avoid all false positives, especially when the data properties yield a high recall. Therefore, negative seeds are employed to learn negative patterns, which boost precision.","Title: Question answering from structured knowledge sources\nYear: 2007\n\nAbstract: We present an implemented approach for domain-restricted question answering from structured knowledge sources, based on robust semantic analysis in a hybrid NLP system architecture. We perform question interpretation and answer extraction in an architecture that builds on a lexical-conceptual structure for question interpretation, which is interfaced with domain-specific concepts and properties in a structured knowledge base. Question interpretation involves a limited amount of domain-specific inferences, and accounts for higher-level quantificational questions. Question interpretation and answer extraction are modular components that interact in clearly defined ways. We derive so-called proto queries from the linguistic representations, which provide partial constraints for answer extraction from the underlying knowledge sources. The search queries we construct from proto queries effectively compute minimal spanning trees from the underlying knowledge sources. Our approach naturally extends to multilingual question answering, and has been developed as a prototype system for two application domains: the domain of Nobel prize winners, and the domain of Language Technology, on the basis of the large ontology underlying the information portal LT World.","Title: Integrating information extraction and automatic hyperlinking\nYear: 2003\n\nAbstract: This paper presents a novel information system integrating advanced information extraction technology and automatic hyper-linking. Extracted entities are mapped into a domain ontology that relates concepts to a selection of hyperlinks. For information extraction, we use SProUT, a generic platform for the development and use of multilingual text processing components. By combining finite-state and unification-based formalisms, the grammar formalism used in SProUT offers both processing efficiency and a high degree of decalrativeness. The ExtraLink demo system show-cases the extraction of relevant concepts from German texts in the tourism domain, offering the direct connection to associated web documents on demand.","Title: Gossip Galore: a self-learning agent for exchanging pop trivia\nYear: 2009\n\nAbstract: This paper describes a self-learning software agent who collects and learns knowledge from the web and also exchanges her knowledge via dialogues with the users. The agent is built on top of information extraction, web mining, question answering and dialogue system technologies, and users can freely formulate their questions within the gossip domain and obtain the answers in multiple ways: textual response, graph-based visualization of the related concepts and speech output.","Title: Extracting and Querying Relations in Scientific Papers on Language Technology\nYear: 2008\n\nAbstract: We describe methods for extracting interesting factual relations from scientific texts in computational linguistics and language technology taken from the ACL Anthology. We use a hybrid NLP architecture with shallow preprocessing for increased robustness and domain-specific, ontology-based named entity recognition, followed by a deep HPSG parser running the English Resource Grammar (ERG). The extracted relations in the MRS (minimal recursion semantics) format are simplified and generalized using WordNet. The resulting 'quriples' are stored in a database from where they can be retrieved (again using abstraction methods) by relation-based search. The query interface is embedded in a web browser-based application we call the Scientist's Workbench. It supports researchers in editing and online-searching scientific papers.","Title: Involving language professionals in the evaluation of machine translation\nYear: 2014\n\nAbstract: Significant breakthroughs in machine translation (MT) only seem possible if human translators are taken into the loop. While automatic evaluation and scoring mechanisms such as BLEU have enabled the fast development of systems, it is not clear how systems can meet real-world (quality) requirements in industrial translation scenarios today. The taraX project has paved the way for wide usage of multiple MT outputs through various feedback loops in system development. The project has integrated human translators into the development process thus collecting feedback for possible improvements. This paper describes results from detailed human evaluation. Performance of different types of translation systems has been compared and analysed via ranking, error analysis and post-editing.","Title: Gossip Galore: An Embodied Conversational Agent for Collecting and Sharing Pop Trivia from the Web\nYear: 2009\n\nAbstract: This paper presents a novel approach to a self-learning agent who collects and learns new knowledge from the web and exchanges her knowledge via dialogues with the users. The application domain is gossip about celebrities in the music world. The agent can inform herself and update the acquired knowledge by observing the web. Fans of musicians can ask for gossip information about stars, bands or people and groups related to them. This agent is built on top of information extraction, web mining, question answering and dialogue system technologies. The minimally supervised machine learning method for relation extraction gives the agent the capability to learn and update knowledge constantly from the web. The extracted relations are structured and linked with each other. Data mining is applied to the learned data to induce the social network among the artists and related people. The knowledge-intensive question answering technology enhanced by domain-specific inference and active memory allows the agent to have vivid and interactive conversations with users by utilizing natural language processing. Users can freely formulate their questions within the gossip data domain and access the answers in different ways: textual response, graph-based visualization of the related concepts and speech output.","Title: Multi-Objective Optimization For The Joint Disambiguation Of Nouns And Named Entities\nYear: 2015\n\nAbstract: In this paper, we present a novel approach to joint word sense disambiguation (WSD) and entity linking (EL) that combines a set of complementary objectives in an extensible multi-objective formalism. During disambiguation the system performs continuous optimization to find optimal probability distributions over candidate senses. The performance of our system on nominal WSD as well as EL improves state-of-the-art results on several corpora. These improvements demonstrate the importance of combining complementary objectives in a joint model for robust disambiguation.","Title: A Web-Based Collaborative Evaluation Tool For Automatically Learned Relation Extraction Patterns\nYear: 2015\n\nAbstract: Patterns extracted from dependency parses of sentences are a major source of knowledge for most state-of-the-art relation extraction systems, but can be of low quality in distantly supervised settings. We present a linguistic annotation tool that allows human experts to analyze and categorize automatically learned patterns, and to identify common error classes. The annotations can be used to create datasets that enable machine learning approaches to pattern quality estimation. We also present an experimental pattern error analysis for three semantic relations, where we find that between 24% and 61% of the learned dependency patterns are defective due to preprocessing or parsing errors, or due to violations of the distant supervision assumption.","Title: TEG-REP: A corpus of Textual Entailment Graphs based on Relation Extraction Patterns.\nYear: 2016\n\nAbstract: The task of relation extraction is to recognize and extract relations between entities or concepts in texts. Dependency parse trees have become a popular source for discovering extraction patterns, which encode the grammatical relations among the phrases that jointly express relation instances. State-of-the-art weakly supervised approaches to relation extraction typically extract thousands of unique patterns only potentially expressing the target relation. Among these patterns, some are semantically equivalent, but differ in their morphological, lexical-semantic or syntactic form. Some express a relation that entails the target relation. We propose a new approach to structuring extraction patterns by utilizing entailment graphs, hierarchical structures representing entailment relations, and present a novel resource of gold-standard entailment graphs based on a set of patterns automatically acquired using distant supervision. We describe the methodology used for creating the dataset and present statistics of the resource as well as an analysis of inference types underlying the entailment decisions.","Title: Relation- and Phrase-level Linking of FrameNet with Sar-graphs.\nYear: 2016\n\nAbstract: Recent research shows the importance of linking linguistic knowledge resources for the creation of large-scale linguistic data. We describe our approach for combining two English resources, FrameNet and sar-graphs, and illustrate the benefits of the linked data in a relation extraction setting. While FrameNet consists of schematic representations of situations, linked to lexemes and their valency patterns, sar-graphs are knowledge resources that connect semantic relations from factual knowledge graphs to the linguistic phrases used to express instances of these relations. We analyze the conceptual similarities and differences of both resources and propose to link sar-graphs and FrameNet on the levels of relations/frames as well as phrases. The former alignment involves a manual ontology mapping step, which allows us to extend sar-graphs with new phrase patterns from FrameNet. The phrase-level linking, on the other hand, is fully automatic. We investigate the quality of the automatically constructed links and identify two main classes of errors.","Title: Event Linking with Sentential Features from Convolutional Neural Networks.\nYear: 2016\n\nAbstract: Coreference resolution for event mentions enables extraction systems to process document-level information. Current systems in this area base their decisions on rich semantic features from various knowledge bases, thus restricting them to domains where such external sources are available. We propose a model for this task which does not rely on such features but instead utilizes sentential features coming from convolutional neural networks. Two such networks first process coreference candidates and their respective context, thereby generating latent-feature representations which are tuned towards event aspects relevant for a linking decision. These representations are augmented with lexicallevel and pairwise features, and serve as input to a trainable similarity function producing a coreference score. Our model achieves state-of-the-art performance on two datasets, one of which is publicly available. An error analysis points out directions for further research.","Title: Real-Time Discovery And Geospatial Visualization Of Mobility And Industry Events From Large-Scale, Heterogeneous Data Streams\nYear: 2016\n\nAbstract: Monitoring mobility- and industry- relevant events is important in areas such as personal travel planning and supply chain management, but extracting events pertaining to specific companies, transit routes and locations from heterogeneous, high-volume text streams remains a significant challenge. We present Spree, a scalable system for real-time, automatic event extraction from social media, news and domain-specific RSS feeds. Our system is tailored to a range of mobility-and industry-related events, and processes German texts within a distributed linguistic analysis pipeline implemented in Apache Flink. The pipeline detects and disambiguates highly ambiguous domain-relevant entities, such as street names, and extracts various events with their geo-locations. Event streams are visualized on a dynamic, interactive map for monitoring and analysis.","Title: Common Round: Application of Language Technologies to Large-Scale Web Debates.\nYear: 2017\n\nAbstract: Web debates play an important role in enabling broad participation of constituen cies in social, political and economic decision-taking. However, it is challenging to organize, structure, and navigate a vast number of diverse argumentations and comments collected from many participants over a long time period. In this paper we demonstrate Common Round, a next generation platform for large-scale web debates, which provides functions for eliciting the semantic content and structures from the contributions of participants. In particular, Common Round applies language technologies for the extraction of semantic essence from textual input, agregation of the formulated opinions and arguments. The platform also provides a cross-lingual access to debates using ma-chine translatio","Title: Creation of an Annotated Corpus of Spanish Radiology Reports.\nYear: 2017\n\nAbstract: This paper presents a new annotated corpus of 513 anonymized radiology reports written in Spanish. Reports were manually annotated with entities, negation and uncertainty terms and relations. The corpus was conceived as an evaluation resource for named entity recognition and relation extraction algorithms, and as input for the use of supervised methods. Biomedical annotated resources are scarce due to confidentiality issues and associated costs. This work provides some guidelines that could help other researchers to undertake similar tasks.","Title: Detecting Named Entities and Relations in German Clinical Reports.\nYear: 2017\n\nAbstract: Clinical notes and discharge summaries are commonly used in the clinical routine and contain patient related information such as well-being, findings and treatments. Information is often described in text form and presented in a semi-structured way. This makes it difficult to access the highly valuable information for patient support or clinical studies. Information extraction can help clinicians to access this information. However, most methods in the clinical domain focus on English data. This work aims at information extraction from German nephrology reports. We present on-going work in the context of detecting named entities and relations. Underlying to this work is a currently generated corpus annotation which includes a large set of different medical concepts, attributes and relations. At the current stage we apply a number of classification techniques to the existing dataset and achieve promising results for most of the frequent concepts and relations.","Title: Fine-grained evaluation of German-English Machine Translation based on a Test Suite.\nYear: 2018\n\nAbstract: We present an analysis of 16 state-of-the-art MT systems on German-English based on a linguistically-motivated test suite. The test suite has been devised manually by a team of language professionals in order to cover a broad variety of linguistic phenomena that MT often fails to translate properly. It contains 5,000 test sentences covering 106 linguistic phenomena in 14 categories, with an increased focus on verb tenses, aspects and moods. The MT outputs are evaluated in a semi-automatic way through regular expressions that focus only on the part of the sentence that is relevant to each phenomenon. Through our analysis, we are able to compare systems based on their performance on these categories. Additionally, we reveal strengths and weaknesses of particular systems and we identify grammatical phenomena where the overall performance of MT is relatively low.","Title: A System for Facilitating and Engancing Web Search\nYear: 1999\n\nAbstract: We present a system that uses semantic methods and natural language processing capabilites in order to provide comprehensive and easy-to-use access to tourist information in the WWW. Thereby. the system is designed such that as background knowledge and linguistic coverage increase, the benefits of the system improve while it guarantees state-of-the-art information and database retrieval capabilities as its bottom line.","Title: Boosting relation extraction with limited closed-world knowledge\nYear: 2010\n\nAbstract: This paper presents a new approach to improving relation extraction based on minimally supervised learning. By adding some limited closed-world knowledge for confidence estimation of learned rules to the usual seed data, the precision of relation extraction can be considerably improved. Starting from an existing baseline system we demonstrate that utilizing limited closed world knowledge can effectively eliminate \"dangerous\" or plainly wrong rules during the bootstrapping process. The new method improves the reliability of the confidence estimation and the precision value of the extracted instances. Although recall suffers to a certain degree depending on the domain and the selected settings, the overall performance measured by F-score considerably improves. Finally we validate the adaptability of the best ranking method to a new domain and obtain promising results."],"string":"[\n \"Title: Categorial Unification Grammars\\nYear: 1986\\n\\nAbstract: Categorial unification grammars (CUGs) embody the essential properties of both unification and categorial grammar formalisms. Their efficient and uniform way of encoding linguistic knowledge in well-understood and widely used representations makes them attractive for computational applications and for linguistic research.In this paper, the basic concepts of CUGs and simple examples of their application will be presented. It will be argued that the strategies and potentials of CUGs justify their further exploration in the wider context of research on unification grammars. Approaches to selected linguistic phenomena such as long-distance dependencies, adjuncts, word order, and extraposition are discussed.\",\n \"Title: LT World: Ontology and Reference Information Portal\\nYear: 2010\\n\\nAbstract: LT World (www.lt-world.org) is an ontology-driven web portal aimed at serving the global language technology community. Ontology-driven means, that the system is driven by an ontological schema to manage the research information and knowledge life-cycles: identify relevant concepts of information, structure and formalize them, assign relationships, functions and views, add states and rules, modify them. For modelling such a complex structure, we employ (i) concepts from the research domain, such as person, organisation, project, tool, data, patent, news, event (ii) concepts from the LT domain, such as technology and resource (iii) concepts from closely related domains, such as language, linguistics, and mathematics. Whereas the research entities represent the general context, that is, a research environment as such, the LT entities define the information and knowledge space of the field, enhanced by entities from closely related areas. By managing information holistically - that is, within a research context - its inherent semantics becomes much more transparent. This paper introduces LT World as a reference information portal through ontological eyes: its content, its system, its method for maintaining knowledge-rich items, its ontology as an asset.\",\n \"Title: Annotating Relation Mentions in Tabloid Press.\\nYear: 2014\\n\\nAbstract: This paper presents a new resource for the training and evaluation needed by relation extraction experiments. The corpus consists of annotations of mentions for three semantic relations: marriage, parent-child, siblings, selected from the domain of biographic facts about persons and their social relationships. The corpus contains more than one hundred news articles from Tabloid Press. In the current corpus, we only consider the relation mentions occurring in the individual sentences. We provide multi-level annotations which specify the marked facts from relation, argument, entity, down to the token level, thus allowing for detailed analysis of linguistic phenomena and their interactions. A generic markup tool Recon developed at the DFKI LT lab has been utilised for the annotation task. The corpus has been annotated by two human experts, supported by additional conflict resolution conducted by a third expert. As shown in the evaluation, the annotation is of high quality as proved by the stated inter-annotator agreements both on sentence level and on relation-mention level. The current corpus is already in active use in our research for evaluation of the relation extraction performance of our automatically learned extraction patterns.\",\n \"Title: Formal constraints on metarules\\nYear: 1983\\n\\nAbstract: Metagrammatical formalisms that combine context-free phrase structure rules and metarules (MPS grammars) allow concise statement of generalizations about the syntax of natural languages. Unconstrained MPS grammars, unfortunately, are not computationally \\\"safe.\\\" We evaluate several proposals for constraining them, basing our assessment on computational tractability and explanatory adequacy. We show that none of them satisfies both criteria, and suggest new directions for research on alternative metagrammatical formalisms.\",\n \"Title: Identifying semantic relations between named entities from chinese texts\\nYear: 2005\\n\\nAbstract: COLLATE is a project dedicated to building up a German authority center for language technology in Saarbrücken. Under this project, a computational model with three-stage pipeline architecture for Chinese information extraction has been proposed. In this paper, we concentrate on the presentation for the third stage, viz., the identification of named entity relations (NERs). A learning and identification approach for NERs called positive and negative case-based learning and identification is described in detail. It pursues the improvement of the identification performance for NERs through simultaneously learning two opposite cases, automatically selecting effective multi-level linguistic features for each NER and non-NER, and optimally achieving an identification tradeoff etc. The experimental results have shown that the overall average recall, precision, and F-measure for 14 NERs are 78.50%, 63.92% and 70.46% respectively. In addition, the above F-measure has been enhanced from 63.61% to 70.46% due to adoption of both positive and negative cases.\",\n \"Title: Hybrid Learning of Dependency Structures from Heterogeneous Linguistic Resources.\\nYear: 2008\\n\\nAbstract: In this paper we present our syntactic and semantic dependency parsing system participated in both closed and open competitions of the CoNLL 2008 Shared Task. By combining the outcome of two state-of-the-art syntactic dependency parsers, we achieved high accuracy in syntactic dependencies (87.32%). With MRSes from grammar-based HPSG parsers, we achieved significant performance improvement on semantic role labeling (from 71.31% to 71.89%), especially in the out-domain evaluation (from 60.16% to 62.11%).\",\n \"Title: Gossip Galore: A Conversational Web Agent for Collecting and Sharing Pop Trivia\\nYear: 2009\\n\\nAbstract: This paper presents a novel approach to a self-learning agent who collects and learns new knowledge from the web and exchanges her knowledge via dialogues with the users. The application domain is gossip about celebrities in the music world. The agent can inform herself and update the acquired knowledge by observing the web. Fans of musicians can ask for gossip information about stars, bands or people and groups related to them. This agent is built on top of information extraction, web mining, question answering and dialogue system technologies. The minimally supervised machine learning method for relation extraction gives the agent the capability to learn and update knowledge constantly from the web. The extracted relations are structured and linked with each other. Data mining is applied to the learned data to induce the social network among the artists and related people. The knowledge-intensive question answering technology enhanced by domain-specific inference and active memory allows the agent to have vivid and interactive conversations with users by utilizing natural language processing. Users can freely formulate their questions within the gossip data domain and access the answers in different ways: textual response, graph-based visualization of the related concepts and speech output.\",\n \"Title: Dependency graphs as a generic interface between parsers and relation extraction rule learning\\nYear: 2011\\n\\nAbstract: In this paper, we propose to use dependency graphs rather than trees as the interface between a parser and the rule acquisition module of a relation extraction (RE) system. Dependency graphs are much more expressive than trees and can easily be adapted to the output representations of various parsers, in particular those with richer semantics. Our approach is built on top of an existing minimally supervised machine learning system for relation extraction. We extend its original tree-based interface to a graph-based representation. In our experiments, we make use of two different dependency parsers and a deep HPSG parser. As expected, switching to a graph representation for the parsers outputting dependency trees does not have any impact on the RE results. But using the graph-based representation for the extraction with deep HPSG analyses improves both recall and f-score of the RE and enables the system to extract more relation instances of higher arity. Furthermore, we also compare the performance among these parsers with respect to their contribution to the RE task. In general, the robust dependency parsers are good in recall. However, the fine-grained deep syntactic parsing wins when it comes to precision.\",\n \"Title: A system for supporting cross-lingual information retrieval\\nYear: 2000\\n\\nAbstract: In this paper, we present the system MULINEX, a fully implemented system which supports cross-lingual search of the WWW. Users can formulate, expand and disambiguate queries, filter the search results and read the retrieved documents by using their native language alone. This multilingual functionality is achieved by the use of dictionary-based query translation, multilingual document categorisation and automatic translation of summaries and documents. The system supports French, German and English and has been installed and tested in the online services of two European internet content and service provider companies. This paper focuses on the techniques and algorithms used in the MULINEX system, explaining how each component works and how it contributes to the overall functionality of the integrated system. The primary system functionalities are outlined from the user perspective, followed by a description of the document database used in the system. The technologies and linguistic resources used in the various system components are then described in detail.\",\n \"Title: Combining multi-engine translations with Moses\\nYear: 2009\\n\\nAbstract: We present a simple method for generating translations with the Moses toolkit (Koehn et al., 2007) from existing hypotheses produced by other translation engines. As the structures underlying these translation engines are not known, an evaluation-based strategy is applied to select systems for combination. The experiments show promising improvements in terms of BLEU.\",\n \"Title: An integrated architecture for shallow and deep processing\\nYear: 2002\\n\\nAbstract: We present an architecture for the integration of shallow and deep NLP components which is aimed at flexible combination of different language technologies for a range of practical current and future applications. In particular, we describe the integration of a high-level HPSG parsing system with different high-performance shallow components, ranging from named entity recognition to chunk parsing and shallow clause recognition. The NLP components enrich a representation of natural language text with layers of new XML meta-information using a single shared data structure, called the text chart. We describe details of the integration methods, and show how information extraction and language checking applications for realworld German text benefit from a deep grammatical analysis.\",\n \"Title: Language Resources and Annotation Tools for Cross-Sentence Relation Extraction.\\nYear: 2014\\n\\nAbstract: In this paper, we present a novel combination of two types of language resources dedicated to the detection of relevant relations (RE) such as events or facts across sentence boundaries. One of the two resources is the sar-graph, which aggregates for each target relation ten thousands of linguistic patterns of semantically associated relations that signal instances of the target relation (Uszkoreit and Xu, 2013). These have been learned from the Web by intra-sentence pattern extraction (Krause et al., 2012) and after semantic filtering and enriching have been automatically combined into a single graph. The other resource is cockrACE, a specially annotated corpus for the training and evaluation of cross-sentence RE. By employing our powerful annotation tool Recon, annotators mark selected entities and relations (including events), coreference relations among these entities and events, and also terms that are semantically related to the relevant relations and events. This paper describes how the two resources are created and how they complement each other.\",\n \"Title: A Linguistically Interpreted Corpus of German Newspaper Text\\nYear: 1998\\n\\nAbstract: In this paper, we report on the development of an annotation scheme and\\nannotation tools for unrestricted German text. Our representation format is\\nbased on argument structure, but also permits the extraction of other kinds of\\nrepresentations. We discuss several methodological issues and the analysis of\\nsome phenomena. Additional focus is on the tools developed in our project and\\ntheir applications.\",\n \"Title: From feature bundles to abstract data types: new directions in the representation and processing of linguistic knowledge\\nYear: 1988\\n\\nAbstract: Without Abstract\",\n \"Title: Large-Scale learning of relation-extraction rules with distant supervision from the web\\nYear: 2012\\n\\nAbstract: We present a large-scale relation extraction (RE) system which learns grammar-based RE rules from the Web by utilizing large numbers of relation instances as seed. Our goal is to obtain rule sets large enough to cover the actual range of linguistic variation, thus tackling the long-tail problem of real-world applications. A variant of distant supervision learns several relations in parallel, enabling a new method of rule filtering. The system detects both binary and n-ary relations. We target 39 relations from Freebase, for which 3M sentences extracted from 20M web pages serve as the basis for learning an average of 40K distinctive rules per relation. Employing an efficient dependency parser, the average run time for each relation is only 19 hours. We compare these rules with ones learned from local corpora of different sizes and demonstrate that the Web is indeed needed for a good coverage of linguistic variation.\",\n \"Title: Chinese named entity and relation identification system\\nYear: 2006\\n\\nAbstract: In this interactive presentation, a Chinese named entity and relation identification system is demonstrated. The domain-specific system has a three-stage pipeline architecture which includes word segmentation and part-of-speech (POS) tagging, named entity recognition, and named entity relation identitfication. The experimental results have shown that the average F-measure for word segmentation and POS tagging after correcting errors achieves 92.86 and 90.01 separately. Moreover, the overall average F-measure for 6 kinds of name entities and 14 kinds of named entity relations is 83.08% and 70.46% respectively.\",\n \"Title: Using syntactic and semantic based relations for dialogue act recognition\\nYear: 2010\\n\\nAbstract: This paper presents a novel approach to dialogue act recognition employing multilevel information features. In addition to features such as context information and words in the utterances, the recognition task utilizes syntactic and semantic relations acquired by information extraction methods. These features are utilized by a Bayesian network classifier for our dialogue act recognition. The evaluation results show a clear improvement from the accuracy of the baseline (only with word features) with 61.9% to an accuracy of 67.4% achieved by the extended feature set.\",\n \"Title: Handling linear precedence constraints by unification\\nYear: 1992\\n\\nAbstract: Linear precedence (LP) rules are widley used for stating word order principles. They have been adopted as constraints by HPSG but no encoding in the formalism has been provided. Since they only order siblings, they are not quite adequate, at least not for German. We propose a notion of LP constraints that applies to linguistically motivated branching domains such as head domains. We show a type-based encoding in an HPSG-style formalism that supports processing. The encoding can be achieved by a compilation step.\",\n \"Title: The Strategic Impact of META-NET on the Regional, National and International Level.\\nYear: 2014\\n\\nAbstract: This article provides an overview of the dissemination work carried out in META-NET from 2010 until 2015; we describe its impact on the regional, national and international level, mainly with regard to politics and the funding situation for LT topics. The article documents the initiativeu0027s work throughout Europe in order to boost progress and innovation in our field.\",\n \"Title: An ontology of systematic relations for a shared grammar of Slavic\\nYear: 2000\\n\\nAbstract: Sharing portions of grammars across languages greatly reduces the costs of multilingual grammar engineering. Related languages share a much wider range of linguistic information than typically assumed in standard multilingual grammar architectures. Taking grammatical relatedness seriously, we are particularly interested in designing linguistically motivated grammatical resources for Slavic languages to be used in applied and theoretical computational linguistics. In order to gain the perspective of a language-family oriented grammar design, we consider an array of systematic relations that can hold between syntactical units. While the categorisation of primitive linguistic entities tends to be language-specific or even construction-specific, the relations holding between them allow various degrees of abstraction. On the basis of Slavic data, we show how a domain ontology conceptualising morpho-syntactic \\\"building blocks\\\" can serve as a basis of a shared grammar of Slavic.\",\n \"Title: Conversational agents in a virtual world\\nYear: 2011\\n\\nAbstract: This paper presents a system that builds on theoretical and experimental insights from linguistic pragmatics, uses novel techniques from computational linguistics and combines them with robust baseline technologies to provide intelligent Non Player Characters (NPCs), which naturally act and talk in a virtual world. Current NPCs still lack the necessary linguistic knowledge and methods to apply them to the numerous conversational application areas in virtual worlds. The system presented in this paper manages two NPCs, a barkeeper and a furniture sales agent, which highly depend on conversational abilities.\",\n \"Title: Challenges and solutions of multilingual and translingual information service systems\\nYear: 2007\\n\\nAbstract: In this paper, we present a survey of challenges and solutions of multilingual and translingual information service systems. In contrast to the computational linguistics literature on such systems, we are approaching the theme here from an HCI perspective. We will argue for a strategy that reduces reliance on automatic free-text translation, language input and classical information retrieval while not giving up these less reliable technologies altogether. We will also opt for a close situation-driven integration of information and communication functionalities. The described solutions have been incorporated into a novel mobile combined information and communication system for foreign tourists that has been tested under realistic conditions by users from several countries. The system is developed by the German-Chinese cooperation project COMPASS20081, a research action within the Digital Olympics framework.\",\n \"Title: Learning relation extraction grammars with minimal human intervention: strategy, results, insights and plans\\nYear: 2011\\n\\nAbstract: The paper describes the operation and evolution of a linguistically oriented framework for the minimally supervised learning of relation extraction grammars from textual data. Cornerstones of the approach are the acquisition of extraction rules from parsing results, the utilization of closed-world semantic seeds and a filtering of rules and instances by confidence estimation. By a systematic walk through the major challenges for this approach the obtained results and insights are summarized. Open problems are addressed and strategies for solving these are outlined.\",\n \"Title: A Seed-driven Bottom-up Machine Learning Framework for Extracting Relations of Various Complexity\\nYear: 2007\\n\\nAbstract: A minimally supervised machine learning framework is described for extracting rela- tions of various complexity. Bootstrapping starts from a small set of n-ary relation in- stances as \\\"seeds\\\", in order to automati- cally learn pattern rules from parsed data, which then can extract new instances of the relation and its projections. We propose a novel rule representation enabling the composition of n-ary relation rules on top of the rules for projections of the relation. The compositional approach to rule con- struction is supported by a bottom-up pat- tern extraction method. In comparison to other automatic approaches, our rules can- not only localize relation arguments but also assign their exact target argument roles. The method is evaluated in two tasks: the extraction of Nobel Prize awards and management succession events. Perfor- mance for the new Nobel Prize task is strong. For the management succession task the results compare favorably with those of existing pattern acquisition ap- proaches.\",\n \"Title: Information Extraction from German Patient Records via Hybrid Parsing and Relation Extraction Strategies.\\nYear: 2014\\n\\nAbstract: In this paper, we report on first attempts and findings to analyzing German patient records, using a hybrid parsing architecture and a combination of two relation extraction strategies. On a practical level, we are interested in the extraction of concepts and relations among those concepts, a necessary cornerstone for building medical information systems. The parsing pipeline consists of a morphological analyzer, a robust chunk parser adapted to Latin phrases used in medical diagnosis, a repair rule stage, and a probabilistic context-free parser that respects the output from the chunker. The relation extraction stage is a combination of two systems: SProUT, a shallow processor which uses hand-written rules to discover relation instances from local text units and DARE which extracts relation instances from complete sentences, using rules that are learned in a bootstrapping process, starting with semantic seeds. Two small experiments have been carried out for the parsing pipeline and the relation extraction stage.\",\n \"Title: COMPASS2008: the smart dining service\\nYear: 2005\\n\\nAbstract: The Compass2008 project is a sino-german cooperation, aiming at integrating advanced information technologies to create a high-tech information system that helps visitors to access location-sensitive information services during the 2008 Olympic Games in their preferred language, offering a variety of service-adaptive modalities available on the mobile devices. In this paper, we demonstrate one of the COMPASS2008 services, the Smart Dining Service, to showcase the new interaction concepts between multimodality, multilingual and location-sensitive information search.\",\n \"Title: Parse reranking for domain-adaptative relation extraction.\\nYear: 2014\\n\\nAbstract: The article demonstrates how generic parsers in a minimally supervised information extraction framework can be adapted to a given task and domain for relation extraction (RE). For the experiments, two parsers that deliver n-best readings are included: (1) a generic deep-linguistic parser (PET) with a largely hand-crafted head-driven phrase structure grammar for English (ERG); (2) a generic statist...\",\n \"Title: A flexible graph-unification formalism and its application to natural-language processing\\nYear: 1988\\n\\nAbstract: A graph-unification-based representation language is described that was developed as the grammar formalism for the LILOG research project at IBM Germany. The Stuttgart Unification Formalism (STUF) differs from its predecessors in its higher flexibility and its algebraic structure. It is well suited for the implementation of rather different linguistic approaches, but is currently employed mainly in the development of Categorial Unification Grammars with a lexicalized compositional semantics. Examples from the syntactic and semantic processing of natural language are used to illustrate the virtues of the formalism and of our lexicalist approach to linguistic analysis.\",\n \"Title: DISCO - An HPSG-based NLP System and its Application for Appointment Scheduling (Project Note).\\nYear: 1994\\n\\nAbstract: The natural language system DISCO is described. It combines o a powerful and\\nflexible grammar development system; o linguistic competence for German\\nincluding morphology, syntax and semantics; o new methods for linguistic\\nperformance modelling on the basis of high-level competence grammars; o new\\nmethods for modelling multi-agent dialogue competence; o an interesting sample\\napplication for appointment scheduling and calendar management.\",\n \"Title: Question Answering Biographic Information and Social Network Powered by the Semantic Web\\nYear: 2010\\n\\nAbstract: After several years of development, the vision of the Semantic Web is gradually becoming reality. Large data repositories have been created and offer semantic information in a machine-processable form for various domains. Semantic Web data can be published on the Web, gathered automatically, and reasoned about. All these developments open interesting perspectives for building a new class of domain-specific, broad-coverage information systems that overcome a long-standing bottleneck of AI systems, the notoriously incomplete knowledge base. We present a system that shows how the wealth of information in the Semantic Web can be interfaced with humans once again, using natural language for querying and answering rather than technical formalisms. Whereas current Question Answering systems typically select snippets from Web documents retrieved by a search engine, we utilize Semantic Web data, which allows us to provide natural-language answers that are tailored to the current dialog context. Furthermore, we show how to use natural language processing technologies to acquire new data and enrich existing data in a Semantic Web framework. Our system has acquired a rich biographic data resource by combining existing Semantic Web resources, which are discovered from semi-structured textual data in Web pages, with information extracted from free natural language texts.\",\n \"Title: GETESS - Searching the Web Exploiting German Texts\\nYear: 1999\\n\\nAbstract: We present an intelligent information agent that uses semantic methods and natural language processing capabilites in order to gather tourist information from theWWWand present it to the human user in an intuitive, user-friendly way. Thereby, the information agent is designed such that as background knowledge and linguistic coverage increase, its benefits improve, while it guarantees state-of-the-art information and database retrieval capabilities as its bottom line.\",\n \"Title: A framework for processing partially free word order\\nYear: 1983\\n\\nAbstract: The partially free word order in German belongs to the class of phenomena in natural language that require a close interaction between syntax and pragmatics. Several competing principles, which are based on syntactic and on discourse information, determine the linear order of noun phrases. A solution to problems of this sort is a prerequisite for high-quality language generation. The linguistic framework of Generalized Phrase Structure Grammar offers tools for dealing with word order variation. Some slight modifications to the framework allow for an analysis of the German data that incorporates just the right degree of interaction between syntactic and pragmatic components and that can account for conflicting ordering statements.\",\n \"Title: Translation combination using factored word substitution\\nYear: 2009\\n\\nAbstract: We present a word substitution approach to combine the output of different machine translation systems. Using part of speech information, candidate words are determined among possible translation options, which in turn are estimated through a pre-computed word alignment. Automatic substitution is guided by several decision factors, including part of speech, local context, and language model probabilities. The combination of these factors is defined after careful manual analysis of their respective impact. The approach is tested for the language pair German-English, however the general technique itself is language independent.\",\n \"Title: An annotation scheme for free word order languages\\nYear: 1997\\n\\nAbstract: We describe an annotation scheme and a tool developed for creating linguistically annotated corpora for non-configurational languages. Since the requirements for such a formalism differ from those posited for configurational languages, several features have been added, influencing the architecture of the scheme. The resulting scheme reflects a stratificational notion of language, and makes only minimal assumptions about the interrelation of the particular representational strata.\",\n \"Title: Software for annotating argument structure\\nYear: 1997\\n\\nAbstract: We present a tool developed for annotating corpora with argument structure representations. The presentation focuses on the architecture of the annotation scheme and a number of techniques for increasing the efficiency and accuracy of annotation. Among others, we show how the assignment of grammatical functions can be automatised using standard part-of-speech tagging methods.\",\n \"Title: A successful field test of a mobile and multilingual information service system COMPASS2008\\nYear: 2007\\n\\nAbstract: We will describe a field test and its evaluation of a truly novel type of mobile computer programs that will assist foreign tourists in their communication with Chinese people. The software is an electronic phrase book and a translation aid but at the same time a powerful multilingual information system connected to numerous services via the Internet. It effectively helps visitors to navigate through the streets, temples and shopping centres of the Beijing megalopolis. It was developed in the German-Chinese project COMPASS 2008, a research action within the Digital Olympics framework. The subjects of the field test were fifteen tourists from seven countries. The test concentrated on usability and acceptance. The applied methodology adapts recognized standards and widely accepted best practice to the specific application type.\",\n \"Title: Talking NPCs in a virtual game world\\nYear: 2010\\n\\nAbstract: This paper describes the KomParse system, a natural-language dialog system in the three-dimensional virtual world Twinity. In order to fulfill the various communication demands between nonplayer characters (NPCs) and users in such an online virtual world, the system realizes a flexible and hybrid approach combining knowledge-intensive domain-specific question answering, task-specific and domain-specific dialog with robust chatbot-like chitchat.\",\n \"Title: YAGO-QA: Answering Questions by Structured Knowledge Queries\\nYear: 2011\\n\\nAbstract: We present a natural-language question-answering system that gives access to the accumulated knowledge of one of the largest community projects on the Web 芒聙\\\" Wikipedia 芒聙\\\" via an automatically acquired structured knowledge base. Key to building such a system is to establish mappings from natural language expressions to semantic representations. We propose to acquire these mappings by data-driven methods 芒聙\\\" corpus harvesting and paraphrasing 芒聙\\\" and present a preliminary empirical study that demonstrates the viability of our method.\",\n \"Title: Further experiments with shallow hybrid MT systems\\nYear: 2010\\n\\nAbstract: We describe our hybrid machine translation system which has been developed for and used in the WMT10 shared task. We compute translations from a rule-based MT system and combine the resulting translation \\\"templates\\\" with partial phrases from a state-of-the-art phrase-based, statistical MT engine. Phrase substitution is guided by several decision factors, a continuation of previous work within our group. For the shared task, we have computed translations for six language pairs including English, German, French and Spanish. Our experiments have shown that our shallow substitution approach can effectively improve the translation result from the RBMT system; however it has also become clear that a deeper integration is needed to further improve translation quality.\",\n \"Title: DFKI hybrid machine translation system for WMT 2011: on the integration of SMT and RBMT\\nYear: 2011\\n\\nAbstract: We present the DFKI hybrid translation system at the WMT workshop 2011. Three SMT and two RBMT systems are combined at the level of the final translation output. The translation results show that our hybrid system significantly outperformed individual systems by exploring strengths of both rule-based and statistical translations.\",\n \"Title: Strategies for adding control information to declarative grammars\\nYear: 1991\\n\\nAbstract: Strategies are proposed for combining different kinds of constraints in declarative grammars with a detachable layer of control information. The added control information is the basis for parametrized dynamically controlled linguistic deduction, a form of linguistic processing that permits the implementation of plausible linguistic performance models without giving up the declarative formulation of linguistic competence. The information can be used by the linguistic processor for ordering the sequence in which conjuncts and disjuncts are processed, for mixing depth-first and breadth-first search, for cutting off undesired derivations, and for constraint-relaxation.\",\n \"Title: Task Driven Coreference Resolution for Relation Extraction\\nYear: 2008\\n\\nAbstract: This paper presents the extension of an existing mimimally supervised rule acquisition method for relation extraction by coreference resolution (CR). To this end, a novel approach to CR was designed and tested. In comparison to state-of-the-art methods for CR, our strategy is driven by the target semantic relation and utilizes domain-specific ontological and lexical knowledge in addition to the learned relation extraction rules. An empirical investigation reveals that newswire texts in our selected domains contain more coreferring noun phrases than prononimal coreferences. This means that existing methods for CR would not suffice and a semantic approach is needed. Our experiments show that the utilization of domain knowledge can boost CR. In our approach, the tasks of relation extraction and CR support each other. On the one hand, reference resolution is needed for the detection of arguments of the target relation. On the other hand, domain modelling for the IE task is used for semantic classification of the referring nouns. Moreover, the application of the learned relation extraction rules often narrows down the number of candidates for CR. With respect to the minimally supervised learning of relation extraction grammars, we design and evaluate two integration strategies: (i) resolution after the complete pattern acquisition process and (ii) resolution embedded in the iterations of the learning process. The evaluation helps us to gain and substantiate a relevant insight: CR effectively improves recall in both strategies but it can hurt the precision because of its error spreading potential.\",\n \"Title: Minimally supervised domain-adaptive parse reranking for relation extraction\\nYear: 2011\\n\\nAbstract: The paper demonstrates how the generic parser of a minimally supervised information extraction framework can be adapted to a given task and domain for relation extraction (RE). For the experiments a generic deep-linguistic parser was employed that works with a largely hand-crafted head-driven phrase structure grammar (HPSG) for English. The output of this parser is a list of n best parses selected and ranked by a MaxEnt parse-ranking component, which had been trained on a more or less generic HPSG treebank. It will be shown how the estimated confidence of RE rules learned from the n best parses can be exploited for parse reranking. The acquired reranking model improves the performance of RE in both training and test phases with the new first parses. The obtained significant boost of recall does not come from an overall gain in parsing performance but from an application-driven selection of parses that are best suited for the RE task. Since the readings best suited for successful rule extraction and instance extraction are often not the readings favored by a regular parser evaluation, generic parsing accuracy actually decreases. The novel method for task-specific parse reranking does not require any annotated data beyond the semantic seed, which is needed anyway for the RE task.\",\n \"Title: Determining the Origin and Structure of Person Names\\nYear: 2010\\n\\nAbstract: This paper presents a novel system HENNA (Hybrid Person Name Analyzer) for identifying language origin and analyzing linguistic structures of person names. We conduct ME-based classification methods for the language origin identification and achieve very promising performance. We will show that word-internal character sequences provide surprisingly strong evidence for predicting the language origin of person names. Our approach is context-, language-and domain-independent and can thus be easily adapted to person names in or from other languages. Furthermore, we provide a novel strategy to handle origin ambiguities or multiple origins in a name. HENNA also provides a person name parser for the analysis of linguistic and knowledge structures of person names. All the knowledge about a person name in HENNA is modelled in a person-name ontology, including relationships between language origins, linguistic features and grammars of person names of a specific language and interpretation of name elements. The approaches presented here are useful extensions of the named entity recognition task.\",\n \"Title: The taraXÜ corpus of human-annotated machine translations.\\nYear: 2014\\n\\nAbstract: Human translators are the key to evaluating machine translation (MT) quality and also to addressing the so far unanswered question when and how to use MT in professional translation workflows. This paper describes the corpus developed as a result of a detailed large scale human evaluation consisting of three tightly connected tasks: ranking, error classification and post-editing.\",\n \"Title: Extracting and Querying Relations in Scientific Papers\\nYear: 2008\\n\\nAbstract: High-precision linguistic and semantic analysis of scientific texts is an emerging research area. We describe methods and an application for extracting interesting factual relations from scientific texts in computational linguistics and language technology. We use a hybrid NLP architecture with shallow preprocessing for increased robustness and domain-specific, ontology-based named entity recognition, followed by a deep HPSG parser running the English Resource Grammar (ERG). The extracted relations in the MRS (minimal recursion semantics) format are simplified and generalized using WordNet. The resulting `quriples' are stored in a database from where they can be retrieved by relation-based search. The query interface is embedded in a web browser-based application we call the Scientist's Workbench. It supports researchers in editing and online-searching scientific papers.\",\n \"Title: Evaluation Resources for Concept-based Cross-Lingual Information Retrieval in the Medical Domain\\nYear: 2004\\n\\nAbstract: The paper describes evaluation resources for concept-based, cross-lingual information retrieval in the medical domain. All resources were constructed in the context of the MuchMore project and are freely available through the project website. Available resources include: a bilingual, parallel document collection of German and English medical scientific abstracts, a set of queries and corresponding relevance assessments, two manually disambiguated test sets for semantic annotation (sense disambiguation), two evaluation lists for German morphological decomposition of medical terms.\",\n \"Title: COMPASS2008: multimodal, multilingual and crosslingual interaction for mobile tourist guide applications\\nYear: 2005\\n\\nAbstract: COMPASS2008 is a general service platform developed to be utilized as the tourist and city explorers assistant within the information services for the Beijing Olympic Games 2008. The main goals of COMPASS2008 are to help foreigners to overcome language barriers in Beijing and assist them in finding information anywhere and anytime they need it. Novel strategies have been developed to exploit the interaction of multimodality, multilinguality and cross-linguality for intelligent information service access and information presentation via mobile devices.\",\n \"Title: Sprinter: Language Technologies for Interactive and Multimedia Language Learning.\\nYear: 2014\\n\\nAbstract: Modern language learning courses are no longer exclusively based on books or face-to-face lectures. More and more lessons make use of multimedia and personalized learning methods. Many of these are based on e-learning solutions. Learning via the Internet provides 7/24 services that require sizeable human resources. Therefore we witness a growing economic pressure to employ computer-assisted methods for improving language learning in quality, efficiency and scalability. In this paper, we will address three applications of language technologies for language learning: 1) Methods and strategies for pronunciation training in second language learning, e.g., multimodal feedback via visualization of sound features, speech verification and prosody transplantation; 2) Dialogue-based language learning games; 3) Application of parsing and generation technologies to the automatic generation of paraphrases for the semi-automatic production of learning material.\",\n \"Title: Semantic Rule Filtering for Web-Scale Relation Extraction\\nYear: 2013\\n\\nAbstract: Web-scale relation extraction is a means for building and extending large repositories of formalized knowledge. This type of automated knowledge building requires a decent level of precision, which is hard to achieve with automatically acquired rule sets learned from unlabeled data by means of distant or minimal supervision. This paper shows how precision of relation extraction can be considerably improved by employing a wide-coverage, general-purpose lexical semantic network, i.e., BabelNet, for effective semantic rule filtering. We apply Word Sense Disambiguation to the content words of the automatically extracted rules. As a result a set of relation-specific relevant concepts is obtained, and each of these concepts is then used to represent the structured semantics of the corresponding relation. The resulting relation-specific subgraphs of BabelNet are used as semantic filters for estimating the adequacy of the extracted rules. For the seven semantic relations tested here, the semantic filter consistently yields a higher precision at any relative recall value in the high-recall range.\",\n \"Title: Evaluation of the KomParse Conversational Non-Player Characters in a Commercial Virtual World.\\nYear: 2012\\n\\nAbstract: The paper describes the evaluation of the KomParse system. KomParse is a dialogue system embedded in a 3-D massive multiplayer online game, allowing conversations between non player characters (NPCs) and game users. In a field test with game users, the system was evaluated with respect to acceptability and usability of the overall system as well as task completion, dialogue control and efficiency of three conversational tasks. Furthermore, subjective feedback has been collected for evaluating the single communication components of the system such as natural language understanding. The results are very satisfying and promising. In general, both the usability and acceptability tests show that the tested NPC is useful and well-accepted by the users. Even if the NPC does not always understand the users well and expresses things unexpected, he could still provide appropriate responses to help users to solve their problems or entertain them.\",\n \"Title: Building a Lexical Sports Ontology for Chinese IE Using Reusable Strategy\\nYear: 2007\\n\\nAbstract: In this paper, we propose a strategy to construct a lexical ontology used for Chinese named entities (NEs) and NE relations (NERs) identification. The lexical information from HowNet (reusable information) and semantic constraints (added information) are semi- automatically integrated into our lexical ontology. In the ontology, addition to the relationships of the concepts in the taxonomy, the non-taxonomic relationships between the concepts have been also built through semantic constraints. The testing results for Chinese named entity and relation identification system have shown that the total average F-measure for six types of NEs and fourteen types of NERs is 83.08% and 70.46% respectively. Therefore, this lexical ontology used for Chinese NE and NER identification is reasonable and effective.\",\n \"Title: Analysis and improvement of minimally supervised machine learning for relation extraction\\nYear: 2009\\n\\nAbstract: The main contribution of this paper is a systematic analysis of a minimally supervised machine learning method for relation extraction grammars. The method is based on a bootstrapping approach in which the bootstrapping is triggered by semantic seeds. The starting point of our analysis is the pattern-learning graph which is a subgraph of the bipartite graph representing all connections between linguistic patterns and relation instances exhibited by the data. It is shown that the performance of such general learning framework for actual tasks is dependent on certain properties of the data and on the selection of seeds. Several experiments have been conducted to gain explanatory insights into the interaction of these two factors. From the investigation of more effective seeds and benevolent data we understand how to improve the learning in less fortunate configurations. A relation extraction method only based on positive examples cannot avoid all false positives, especially when the data properties yield a high recall. Therefore, negative seeds are employed to learn negative patterns, which boost precision.\",\n \"Title: Question answering from structured knowledge sources\\nYear: 2007\\n\\nAbstract: We present an implemented approach for domain-restricted question answering from structured knowledge sources, based on robust semantic analysis in a hybrid NLP system architecture. We perform question interpretation and answer extraction in an architecture that builds on a lexical-conceptual structure for question interpretation, which is interfaced with domain-specific concepts and properties in a structured knowledge base. Question interpretation involves a limited amount of domain-specific inferences, and accounts for higher-level quantificational questions. Question interpretation and answer extraction are modular components that interact in clearly defined ways. We derive so-called proto queries from the linguistic representations, which provide partial constraints for answer extraction from the underlying knowledge sources. The search queries we construct from proto queries effectively compute minimal spanning trees from the underlying knowledge sources. Our approach naturally extends to multilingual question answering, and has been developed as a prototype system for two application domains: the domain of Nobel prize winners, and the domain of Language Technology, on the basis of the large ontology underlying the information portal LT World.\",\n \"Title: Integrating information extraction and automatic hyperlinking\\nYear: 2003\\n\\nAbstract: This paper presents a novel information system integrating advanced information extraction technology and automatic hyper-linking. Extracted entities are mapped into a domain ontology that relates concepts to a selection of hyperlinks. For information extraction, we use SProUT, a generic platform for the development and use of multilingual text processing components. By combining finite-state and unification-based formalisms, the grammar formalism used in SProUT offers both processing efficiency and a high degree of decalrativeness. The ExtraLink demo system show-cases the extraction of relevant concepts from German texts in the tourism domain, offering the direct connection to associated web documents on demand.\",\n \"Title: Gossip Galore: a self-learning agent for exchanging pop trivia\\nYear: 2009\\n\\nAbstract: This paper describes a self-learning software agent who collects and learns knowledge from the web and also exchanges her knowledge via dialogues with the users. The agent is built on top of information extraction, web mining, question answering and dialogue system technologies, and users can freely formulate their questions within the gossip domain and obtain the answers in multiple ways: textual response, graph-based visualization of the related concepts and speech output.\",\n \"Title: Extracting and Querying Relations in Scientific Papers on Language Technology\\nYear: 2008\\n\\nAbstract: We describe methods for extracting interesting factual relations from scientific texts in computational linguistics and language technology taken from the ACL Anthology. We use a hybrid NLP architecture with shallow preprocessing for increased robustness and domain-specific, ontology-based named entity recognition, followed by a deep HPSG parser running the English Resource Grammar (ERG). The extracted relations in the MRS (minimal recursion semantics) format are simplified and generalized using WordNet. The resulting 'quriples' are stored in a database from where they can be retrieved (again using abstraction methods) by relation-based search. The query interface is embedded in a web browser-based application we call the Scientist's Workbench. It supports researchers in editing and online-searching scientific papers.\",\n \"Title: Involving language professionals in the evaluation of machine translation\\nYear: 2014\\n\\nAbstract: Significant breakthroughs in machine translation (MT) only seem possible if human translators are taken into the loop. While automatic evaluation and scoring mechanisms such as BLEU have enabled the fast development of systems, it is not clear how systems can meet real-world (quality) requirements in industrial translation scenarios today. The taraX project has paved the way for wide usage of multiple MT outputs through various feedback loops in system development. The project has integrated human translators into the development process thus collecting feedback for possible improvements. This paper describes results from detailed human evaluation. Performance of different types of translation systems has been compared and analysed via ranking, error analysis and post-editing.\",\n \"Title: Gossip Galore: An Embodied Conversational Agent for Collecting and Sharing Pop Trivia from the Web\\nYear: 2009\\n\\nAbstract: This paper presents a novel approach to a self-learning agent who collects and learns new knowledge from the web and exchanges her knowledge via dialogues with the users. The application domain is gossip about celebrities in the music world. The agent can inform herself and update the acquired knowledge by observing the web. Fans of musicians can ask for gossip information about stars, bands or people and groups related to them. This agent is built on top of information extraction, web mining, question answering and dialogue system technologies. The minimally supervised machine learning method for relation extraction gives the agent the capability to learn and update knowledge constantly from the web. The extracted relations are structured and linked with each other. Data mining is applied to the learned data to induce the social network among the artists and related people. The knowledge-intensive question answering technology enhanced by domain-specific inference and active memory allows the agent to have vivid and interactive conversations with users by utilizing natural language processing. Users can freely formulate their questions within the gossip data domain and access the answers in different ways: textual response, graph-based visualization of the related concepts and speech output.\",\n \"Title: Multi-Objective Optimization For The Joint Disambiguation Of Nouns And Named Entities\\nYear: 2015\\n\\nAbstract: In this paper, we present a novel approach to joint word sense disambiguation (WSD) and entity linking (EL) that combines a set of complementary objectives in an extensible multi-objective formalism. During disambiguation the system performs continuous optimization to find optimal probability distributions over candidate senses. The performance of our system on nominal WSD as well as EL improves state-of-the-art results on several corpora. These improvements demonstrate the importance of combining complementary objectives in a joint model for robust disambiguation.\",\n \"Title: A Web-Based Collaborative Evaluation Tool For Automatically Learned Relation Extraction Patterns\\nYear: 2015\\n\\nAbstract: Patterns extracted from dependency parses of sentences are a major source of knowledge for most state-of-the-art relation extraction systems, but can be of low quality in distantly supervised settings. We present a linguistic annotation tool that allows human experts to analyze and categorize automatically learned patterns, and to identify common error classes. The annotations can be used to create datasets that enable machine learning approaches to pattern quality estimation. We also present an experimental pattern error analysis for three semantic relations, where we find that between 24% and 61% of the learned dependency patterns are defective due to preprocessing or parsing errors, or due to violations of the distant supervision assumption.\",\n \"Title: TEG-REP: A corpus of Textual Entailment Graphs based on Relation Extraction Patterns.\\nYear: 2016\\n\\nAbstract: The task of relation extraction is to recognize and extract relations between entities or concepts in texts. Dependency parse trees have become a popular source for discovering extraction patterns, which encode the grammatical relations among the phrases that jointly express relation instances. State-of-the-art weakly supervised approaches to relation extraction typically extract thousands of unique patterns only potentially expressing the target relation. Among these patterns, some are semantically equivalent, but differ in their morphological, lexical-semantic or syntactic form. Some express a relation that entails the target relation. We propose a new approach to structuring extraction patterns by utilizing entailment graphs, hierarchical structures representing entailment relations, and present a novel resource of gold-standard entailment graphs based on a set of patterns automatically acquired using distant supervision. We describe the methodology used for creating the dataset and present statistics of the resource as well as an analysis of inference types underlying the entailment decisions.\",\n \"Title: Relation- and Phrase-level Linking of FrameNet with Sar-graphs.\\nYear: 2016\\n\\nAbstract: Recent research shows the importance of linking linguistic knowledge resources for the creation of large-scale linguistic data. We describe our approach for combining two English resources, FrameNet and sar-graphs, and illustrate the benefits of the linked data in a relation extraction setting. While FrameNet consists of schematic representations of situations, linked to lexemes and their valency patterns, sar-graphs are knowledge resources that connect semantic relations from factual knowledge graphs to the linguistic phrases used to express instances of these relations. We analyze the conceptual similarities and differences of both resources and propose to link sar-graphs and FrameNet on the levels of relations/frames as well as phrases. The former alignment involves a manual ontology mapping step, which allows us to extend sar-graphs with new phrase patterns from FrameNet. The phrase-level linking, on the other hand, is fully automatic. We investigate the quality of the automatically constructed links and identify two main classes of errors.\",\n \"Title: Event Linking with Sentential Features from Convolutional Neural Networks.\\nYear: 2016\\n\\nAbstract: Coreference resolution for event mentions enables extraction systems to process document-level information. Current systems in this area base their decisions on rich semantic features from various knowledge bases, thus restricting them to domains where such external sources are available. We propose a model for this task which does not rely on such features but instead utilizes sentential features coming from convolutional neural networks. Two such networks first process coreference candidates and their respective context, thereby generating latent-feature representations which are tuned towards event aspects relevant for a linking decision. These representations are augmented with lexicallevel and pairwise features, and serve as input to a trainable similarity function producing a coreference score. Our model achieves state-of-the-art performance on two datasets, one of which is publicly available. An error analysis points out directions for further research.\",\n \"Title: Real-Time Discovery And Geospatial Visualization Of Mobility And Industry Events From Large-Scale, Heterogeneous Data Streams\\nYear: 2016\\n\\nAbstract: Monitoring mobility- and industry- relevant events is important in areas such as personal travel planning and supply chain management, but extracting events pertaining to specific companies, transit routes and locations from heterogeneous, high-volume text streams remains a significant challenge. We present Spree, a scalable system for real-time, automatic event extraction from social media, news and domain-specific RSS feeds. Our system is tailored to a range of mobility-and industry-related events, and processes German texts within a distributed linguistic analysis pipeline implemented in Apache Flink. The pipeline detects and disambiguates highly ambiguous domain-relevant entities, such as street names, and extracts various events with their geo-locations. Event streams are visualized on a dynamic, interactive map for monitoring and analysis.\",\n \"Title: Common Round: Application of Language Technologies to Large-Scale Web Debates.\\nYear: 2017\\n\\nAbstract: Web debates play an important role in enabling broad participation of constituen cies in social, political and economic decision-taking. However, it is challenging to organize, structure, and navigate a vast number of diverse argumentations and comments collected from many participants over a long time period. In this paper we demonstrate Common Round, a next generation platform for large-scale web debates, which provides functions for eliciting the semantic content and structures from the contributions of participants. In particular, Common Round applies language technologies for the extraction of semantic essence from textual input, agregation of the formulated opinions and arguments. The platform also provides a cross-lingual access to debates using ma-chine translatio\",\n \"Title: Creation of an Annotated Corpus of Spanish Radiology Reports.\\nYear: 2017\\n\\nAbstract: This paper presents a new annotated corpus of 513 anonymized radiology reports written in Spanish. Reports were manually annotated with entities, negation and uncertainty terms and relations. The corpus was conceived as an evaluation resource for named entity recognition and relation extraction algorithms, and as input for the use of supervised methods. Biomedical annotated resources are scarce due to confidentiality issues and associated costs. This work provides some guidelines that could help other researchers to undertake similar tasks.\",\n \"Title: Detecting Named Entities and Relations in German Clinical Reports.\\nYear: 2017\\n\\nAbstract: Clinical notes and discharge summaries are commonly used in the clinical routine and contain patient related information such as well-being, findings and treatments. Information is often described in text form and presented in a semi-structured way. This makes it difficult to access the highly valuable information for patient support or clinical studies. Information extraction can help clinicians to access this information. However, most methods in the clinical domain focus on English data. This work aims at information extraction from German nephrology reports. We present on-going work in the context of detecting named entities and relations. Underlying to this work is a currently generated corpus annotation which includes a large set of different medical concepts, attributes and relations. At the current stage we apply a number of classification techniques to the existing dataset and achieve promising results for most of the frequent concepts and relations.\",\n \"Title: Fine-grained evaluation of German-English Machine Translation based on a Test Suite.\\nYear: 2018\\n\\nAbstract: We present an analysis of 16 state-of-the-art MT systems on German-English based on a linguistically-motivated test suite. The test suite has been devised manually by a team of language professionals in order to cover a broad variety of linguistic phenomena that MT often fails to translate properly. It contains 5,000 test sentences covering 106 linguistic phenomena in 14 categories, with an increased focus on verb tenses, aspects and moods. The MT outputs are evaluated in a semi-automatic way through regular expressions that focus only on the part of the sentence that is relevant to each phenomenon. Through our analysis, we are able to compare systems based on their performance on these categories. Additionally, we reveal strengths and weaknesses of particular systems and we identify grammatical phenomena where the overall performance of MT is relatively low.\",\n \"Title: A System for Facilitating and Engancing Web Search\\nYear: 1999\\n\\nAbstract: We present a system that uses semantic methods and natural language processing capabilites in order to provide comprehensive and easy-to-use access to tourist information in the WWW. Thereby. the system is designed such that as background knowledge and linguistic coverage increase, the benefits of the system improve while it guarantees state-of-the-art information and database retrieval capabilities as its bottom line.\",\n \"Title: Boosting relation extraction with limited closed-world knowledge\\nYear: 2010\\n\\nAbstract: This paper presents a new approach to improving relation extraction based on minimally supervised learning. By adding some limited closed-world knowledge for confidence estimation of learned rules to the usual seed data, the precision of relation extraction can be considerably improved. Starting from an existing baseline system we demonstrate that utilizing limited closed world knowledge can effectively eliminate \\\"dangerous\\\" or plainly wrong rules during the bootstrapping process. The new method improves the reliability of the confidence estimation and the precision value of the extracted instances. Although recall suffers to a certain degree depending on the domain and the selected settings, the overall performance measured by F-score considerably improves. Finally we validate the adaptability of the best ranking method to a new domain and obtain promising results.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":71,"string":"71"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":269,"string":"269"}}},{"rowIdx":270,"cells":{"question_id":{"kind":"string","value":"Peter Steenkiste"},"question":{"kind":"string","value":"Generate an abstract for the title \"An Internet-style approach to wireless link errors.\" using the following items: Wireless links, packet loss, transmission errors, transport-level protocols, link scheduling"},"answer":{"kind":"string","value":"Wireless links differ from traditional 'wired' links in two ways that challenge the existing Internet. On wireless links packet loss or corruption due to transmission errors is not rare, which calls into question the standard Internet assumptions that transmission errors should be corrected by transport-level protocols at end systems and that end-to-end packet loss typically indicates network congestion. Also, the severity and location-dependent nature of these errors calls into question the meaning of 'fair' scheduling, per-flow quality of service, and even looser notions such as service level agreements, when applied to wireless links. An important question is whether the two unique problems posed by wireless links can be successfully addressed within the standard Internet architecture, as opposed to requiring new transport protocols designed specifically for wireless links or requiring wireless links to 'fix up' the operation of specific end-to-end protocols. We provide experimental evidence that a combination of protocol-blind link-level local error control, which lessens the damage, and error-sensitive link scheduling, which ensures sensible outcomes in response to link capacity loss, provides a good operating environment while adhering to traditional Internet design practices. Copyright (C) 2001 John Wiley Sons, Ltd."},"correct_answer":{"kind":"string","value":"Wireless links differ from traditional 'wired' links in two ways that challenge the existing Internet. On wireless links packet loss or corruption due to transmission errors is not rare, which calls into question the standard Internet assumptions that transmission errors should be corrected by transport-level protocols at end systems and that end-to-end packet loss typically indicates network congestion. Also, the severity and location-dependent nature of these errors calls into question the meaning of 'fair' scheduling, per-flow quality of service, and even looser notions such as service level agreements, when applied to wireless links. An important question is whether the two unique problems posed by wireless links can be successfully addressed within the standard Internet architecture, as opposed to requiring new transport protocols designed specifically for wireless links or requiring wireless links to 'fix up' the operation of specific end-to-end protocols. We provide experimental evidence that a combination of protocol-blind link-level local error control, which lessens the damage, and error-sensitive link scheduling, which ensures sensible outcomes in response to link capacity loss, provides a good operating environment while adhering to traditional Internet design practices. Copyright (C) 2001 John Wiley Sons, Ltd."},"documents":{"kind":"list like","value":["Title: Parallelizing a New Class of Large Applications over High-speed Networks\nYear: 1991\n\nAbstract: parallel architecture. In both cases, the efforts require Several large applications have been parallelized that the persons responsible for the porting are on Nectar, a network-based multicomputer recently intimately familiar with the applications. Since large developed by Carnegie Mellon. These applications applications tend to involve substantial application- were previously either too large or too complex to be specific knowledge, this implies that often only easily implemented on distributed memory parallel application scientists themselves can do the porting. systems. Parallelizing these applications was made possible by the cooperative use of many existing This definitely is not the best way of using their time, general-purpose computers over high-speed and as a result, many large applications have never been networks, and by an implementation methodology implemented on parallel machines. based on a clean separation between application- specific and system-specific code. We illustrate What we need are parallel architectures and these points using our experience with parallelizing programming tools to provide direct and general three real-world applications. The success in these support for parallelizing large applications. These tools applications clearly points out a new direction in parallel processing. should be at a higher level than send and receive primitives, or synchronization or shared data primitives. The objective is to be able to port large applications","Title: Customizable virtual private network service with QoS\nYear: 2001\n\nAbstract: In this paper, we propose and implement Virtual NetworkService #VNS#, a value-added network servicefor deploying virtual private networks #VPN# in amanaged wide area IP network. The key feature ofVNS is its capability of providing a customer with aVPN that is customizable with management capabilitiesand performance properties comparable to a dedicatedphysical network. In addition, VNS ensurescon#dentiality of data and principals through the useof IPSEC. The main technique underlying...","Title: Building Self-Configuring Services Using Service-Specific Knowledge\nYear: 2004\n\nAbstract: A self-configuring service can automatically leverage distributed service components and resources to compose an optimal configuration according to both the requirements of a particular user and the system characteristics. One major challenge for building such services is how to bring in service-specific knowledge, e.g., what components are needed and optimization criteria to use, while still allowing reuse of common service composition functionalities. In this paper, we present an architecture in which service developers express their service-specific knowledge in the form of a service recipe that is used by a generic synthesizer to perform service composition automatically. We apply our approach to three different services to illustrate the flexibility and simplicity of the recipe representation. We use simulations based on Internet measurements to evaluate how an appropriate optimization algorithm can be selected according to a developer's service-specific trade-off between optimality and cost of optimization.","Title: Low-overhead channel-aware rate adaptation\nYear: 2007\n\nAbstract: Current rate selection algorithms are dominated by probe-based approaches that search for the best transmission rate using trial-and-error. When operating over a dynamic channel, probe-based techniques can perform poorly since they inefficiently search for the moving target presented by the constantly changing channel. We have developed a channel-aware rate adaptation algorithm - CHARM - that responds quickly to dynamic channel changes, and significantly outperforms probe-based algorithms in many instances. Unlike previous approaches, CHARM leverages channel reciprocity to obtain channel information without incurring RTS/CTS overhead. Our work shows that channel-aware rate selection is viable, and can significantly outperform probe-based rate adaptation over both static and dynamic channels.","Title: Understanding tradeoffs in incremental deployment of new network architectures\nYear: 2013\n\nAbstract: Despite the plethora of incremental deployment mechanisms proposed, rapid adoption of new network-layer protocols and architectures remains difficult as reflected by the widespread lack of IPv6 traffic on the Internet. We show that all deployment mechanisms must address four key questions: How to select an egress from the source network, how to select an ingress into the destination network, how to reach that egress, and how to reach that ingress. By creating a design space that maps all existing mechanisms by how they answer these questions, we identify the lack of existing mechanisms in part of this design space and propose two novel approaches: the \"4ID\" and the \"Smart 4ID\". The 4ID mechanism utilizes new data plane technology to flexibly decide when to encapsulate packets at forwarding time. The Smart 4ID mechanism additionally adopts an SDN-style control plane to intelligently pick ingress/egress pairs based on a wider view of the local network. We implement these mechanisms along with two widely used IPv6 deployment mechanisms and conduct wide-area deployment experiments over PlanetLab. We conclude that Smart 4ID provide better overall performance and failure semantics, and that innovations in the data plane and control plane enable straightforward incremental deployment.","Title: Discovery and Composition of Per-Domain Behaviours - a Service Abstraction Approach.\nYear: 2010\n\nAbstract: We discuss the problem of composing Quality-of-Service across several administrative domains considering an evolved DiffServ notion of Per-Domain Behavior (PDB). We discuss two components of the problem: path discovery and the effect of composing PDBs. We assume the most general scenario: domains are free to adopt any PDB, as long there are common semantics and a set of well-known QoS parameters (e. g. one-way delay, peak/sustained bandwidth, etc.). Thus we adopt an abstract representation of PDBs.We obtain three main results. First, we show that a distributed path discovery scheme is feasible and more scalable than a centralized one. Second, we show the outcome of inter-domain QoS composition, for general metrics and for Internet-alike topologies. Finally, and as an important practical result, we show that the Internet may not need a centralized governance model, in terms of the definition of inter-domain PDBs.","Title: Exploiting Information Relationships for Access Control\nYear: 2005\n\nAbstract: Pervasive computing environments offer a multitude of information services that provide potentially complex types of information. Therefore, when running access control for sensitive information, these environments need to take relationships between information into account. Other approaches to relationship-aware access control (e.g., based on Semantic Web rule engines) are often expensive and based on a centralized design. In this paper, we identify three types of information relationships (bundling-based, combination-based, and granularity-based) that are common and important in pervasive computing, and we integrate support for them in a distributed, certificate-based access control architecture. In our approach, access control is fully distributed while sophisticated rule engines can still be used to deal with more complex access control cases. To demonstrate the feasibility of our design, we give a complexity analysis of the architecture and a performance analysis of a prototype implementation.","Title: Supporting Dynamic Inter-Class Resource Sharing: A Multi-Class Qos Routing Algorithm\nYear: 1999\n\nAbstract: In an integrated services network, resources are shared by multiple traffic classes. Service classes that deliver Quality-of-Service (QoS) to applications have priority over others that do not. In such a multi-service network, routing decisions for high priority QoS traffic will affect what resources are available for lower priority traffic: Poor route selection can result in congestion for, or even starvation of, lower priority traffic. Whereas many studies have focused on routing algorithms that optimize the network throughput for individual service classes, little effort has been devoted to routing algorithms that address inter-class resource sharing. In this paper, we propose a routing algorithm that allows dynamic sharing of link resources among multiple traffic classes. The algorithm is based on the concept of \"virtual residual bandwidth,\" which is derived from the link residual bandwidth by taking the congestion condition of low priority traffic into account. By using the virtual residual bandwidth in the link cost function for QoS sessions, we discourages QoS sessions from using links that are heavily loaded with low priority traffic. Our approach is simple in the sense that besides changing the link cost function, no other changes to the routing algorithms for individual service classes are required. An extensive simulation study shows that when the traffic load is unevenly distributed, significant performance improvements can be achieved for low priority traffic without sacrificing performance for high priority traffic. The result demonstrates that QoS routing is important even when the QoS traffic load is light and call blocking is not an issue.","Title: Supporting dynamic inter-domain network composition: domain discovery\nYear: 2009\n\nAbstract: When two administratively independent domains need to engage in cooperation of some kind, some initial common known point of contact must exist, both in terms of the application topological position (i.e., IP address, transport protocol and port) and in terms of the interface technology (e.g., the protocol suite of the interaction). In a world of many domains of many types (not necessarily Autonomous Systems in the sense of interdomain routing), manual or single-directory-based operations are not practical (or even feasible); hence, some form of autonomic discovery and handshaking of domains is needed. We propose and evaluate several strategies to allow autonomic bootstrapping of inter-domain operations, all fit to be deployed as BGP extensions. We show the time/message overhead tradeoff: it's possible to obtain the absolute minimum message complexity of O(N) but at the cost of central administrative burden or, for fully distributed schemes, a tradeoff (message/time complexity) of O(N2)/O(N) or O(N2)/O(log2N).","Title: Design, Implementation, and Evaluation of the Remos Network Monitoring System\nYear: 2003\n\nAbstract: Remos provides resource information to distributed applications. Its design goals of scalability, flexibility, and portability are achieved through an architecture that allows components to be positioned across the network, each collecting information about its local network. To collect information from different types of networks, Remos provides several Collectors that use different technologies, including SNMP and benchmarking. By matching the Collector to the particular network environment and by providing an architecture for distributing the output of these collectors across all querying environments, Remos collects appropriately detailed information at each site and distributes this information where needed in a scalable manner. Remos has been implemented and tested in a variety of networks and is in use in a number of different environments.","Title: A statistical channel model for realistic simulation in VANET.\nYear: 2012\n\nAbstract: Vehicular Ad-hoc NETwork (VANET) simulation is crucial for the development of new protocols and applications. Even though real-world experimentation is the de facto benchmarking solution for any of these, the first evaluations must be made through simulation, due to the ease of changing parameters and scenarios.In this work, we propose a statistical channel model for VANET simulation based on the observation of data from real-world experiments, obtained from an IEEE 802.11p/WAVE compliant testbed. We statistically characterize fading in VANET communication and propose a combination of models for Line-of-Sight (LoS) transmission.Simulations using the proposed model were compared with real-world experiment results and, furthermore, the model was validated against a set of measurements from an independent research group, fitting it with a high concordance level, thus proving to be effective and general.","Title: Network-Sensitive Service Discovery\nYear: 2003\n\nAbstract: We consider the problem of network-sensitive service selection (NSSS): finding services that match a partic- ular set of functional and network properties. Cur- rent solutions handle this problem using a two-step pro- cess. First, a user obtains a list of candidates through service discovery. Then, the user applies a network- sensitive server selection technique to find the best ser- vice. Such approaches are complex and expensive since each user has to solve the NSSS problem inde- pendently. In this paper, we present a simple alterna- tive: network-sensitive service discovery (NSSD). By in- tegrating network-sensitivity into the service discovery process, NSSD allows users who are looking for services to specify both the desired functional and network prop- erties at the same time. Users benefit since they only have to solve a restricted version of the server selection problem. Moreover, NSSD can solve the NSSS problem more efficiently by amortizing the overhead over many users. We present the design of NSSD, a prototype im- plementation, and experimental results that illustrate how NSSD can be utilized for different applications.","Title: DIRC: increasing indoor wireless capacity using directional antennas\nYear: 2009\n\nAbstract: The demand for wireless bandwidth in indoor environments such as homes and offices continues to increase rapidly. Although wireless technologies such as MIMO can reach link throughputs of 100s of Mbps (802.11n) for a single link, the question of how we can deliver high throughput to a large number of densely-packed devices remains an open problem. Directional antennas have been shown to be an effective way to increase spatial reuse, but past work has focused largely on outdoor environments where the interactions between wireless links can usually be ignored. This assumption is not acceptable in dense indoor wireless networks since indoor deployments need to deal with rich scattering and multipath effects. In this paper we introduce DIRC, a wireless network design whose access points use phased array antennas to achieve high throughput in dense, indoor environments. The core of DIRC is an algorithm that increases spatial reuse and maximizes overall network capacity by optimizing the orientations of a network of directional antennas. We implemented DIRC and evaluated it on a nine node network in an enterprise setting. Our results show that DIRC improves overall network capacity in indoor environments, while being flexible enough to adapt to node mobility and changing traffic workloads.","Title: Aroma: Language Support for Distributed Objects\nYear: 1992\n\nAbstract: Aroma simplifies the task of parallelizing large applications in multicomputers by providing applications with a shared object space. Aroma supports both traditional monolithic objects and aggregate objects that can be partitioned across multiple nodes. Aggregate objects support data parallelism efficiently. An Aroma program consists of tasks that operate on shared objects. Tasks typically execute on the node on which their input data is located, thus minimizing communication. Shared data objects have synchronization properties associated with them, making it possible to parallelize a large class of applications without using explicit, locks and condition variables. The authors present and justify the Aroma language features, and give examples of Aroma programs. Aroma has been implemented on the Nectar multicomputer. The authors give performance results for several applications.","Title: Analyzing communication latency using the Nectar communication processor\nYear: 1992\n\nAbstract: For multicomputer applications, the most important performance parameters of a network is the latency for short messages. In this paper we present an analysis of communication latency using measurement of the Nectar system. Nectar is a high-performance multicomputer built around a high-bandwidth crosspoint network. Nodes are connected to the Nectar network using network coprocessors that are primarily responsible the protocol processing, but that can also execute application code. This architecture allows us to analyze message latency both between workstations with an outboard protocol engine and between lightweight nodes with a minimal runtime system and a fast, simple network interface (the coprocessors). We study how much context switching, buffer management and protocol processing contribute to the communication latency and we discuss how the latency is influenced by the protocol implementation.","Title: Distributed Load-Sensitive Routing For Computationally-Constrained Flows\nYear: 2003\n\nAbstract: A network that provides not only connectivity but also computational resources to application flows will enable a new array of network services. For example, applications that require content adaptation can be deployed more easily in a network that provides integrated communication and computational resources. In this paper, we study the problem of finding a path for a flow that has both computational and bandwidth constraints. We present a distributed load-sensitive routing algorithm that generates precomputed routing information and optimizes the routing decisions for both applications and computational and communication resource providers. We show through simulations that our distributed approach performs comparably to a centralized algorithm and is more resilient to longer routing update intervals.","Title: Project Aura: Toward Distraction-Free Pervasive Computing\nYear: 2002\n\nAbstract: Today's systems distract users in many ways, thereby reducing their effectiveness. Aura aims to minimize user distractions by trading plentiful computing resources for this scarcest of resources. Aura's approach is based on two broad concepts. First, it uses proactivity, so a system layer can anticipate requests from a higher layer. Second, it is self-tuning, so layers can adapt by observing current demands and adjusting their performance and resource usage characteristics accordingly. By applying these concepts at every layer in the system, the authors hope to build an environment that adapts to the user's context and needs with minimal user involvement. They will deploy a large-scale Aura system at Carnegie Mellon to help evaluate the research in a realistic setting.","Title: Customizable Cooperative Metering for Multi-ingress Service Level Agreements in Differentiated Network Services\nYear: 2001\n\nAbstract: In the Differentiated Service architecture an interesting class of SLAs provides guarantees for the traffic flowing from multiple ingress nodes into a single or group of egress nodes. For many distributed services, like a VPN service, where multiple ingress points are sending to the same egress, customers would like to control the bandwidth distribution across the ingress routers, based on their specific requirements. In this paper we present a simple strategy called CCDM (Customized Coordinated Dynamic Metering) that supports a customizable distribution of bandwidth across ingress routers. The bandwidth distribution policy is specified by customers in the form of router extensions (code modules) that execute in the control plane of the ingress routers. We describe and motivate the CCDM design. We also describe an implementation of CCDM in the context of the Darwin system and present measurement results for three different customized policies, demonstrating the customizability aspect of our solution.","Title: Virtual traffic lights in partial deployment scenarios.\nYear: 2013\n\nAbstract: Vehicular ad hoc networks (VANETs) are seen as an important enabling technology for improving both traffic safety and efficiency. Virtual Traffic Lights (VTLs) are a promising proposal for reducing travel time by efficiently controlling road intersections. VTLs use vehicle-to-vehicle communication to dynamically optimize traffic flow and they display traffic light information on the windshield. However, research so far has assumed that all vehicles are equipped with VTL support and it has ignored the incremental deployment phase, which could last decades. In this paper we present a solution for a VTL partial deployment scenario that is based on the idea of having VTL equipped cars display traffic light information on the outside of the vehicle. This allows drivers in non-equipped vehicles, or even pedestrians, to see the light color and respond accordingly. We show that the benefits of VTLs in terms of intersection throughput and average delay reduction grow as a function of the penetration rate of equipped vehicles.","Title: Network-Aware Distributed Computing: A Case Study\nYear: 1998\n\nAbstract: The development of network-aware applications, i.e. applications that dynamically adapt to network conditions, has had some success in the domain of multimedia applications, but progress has been very slow for distributed computing applications. The reason is that the relationship between application performance and network performance is typically more complex for that class of applications, making adaptation difficult. In this paper are introduce two adaptation methods for distributed computing applications, one based on a performance model and another based on balancing computation and communication time. We illustrate the two methods using a simple distributed application (matrix multiply) and compare their performance. We show that both methods can correctly estimate the best number of nodes to use on our testbed. We also show that both methods have weaknesses. Model-based adaptation requires an accurate performance model and is sensitive to errors in measurements of the system parameters. The ratio-based method is more robust but less general.","Title: User-Level Protocol Servers with Kernel-Level Performance\nYear: 1998\n\nAbstract: Compared to kernel-level servers, user-level ones can be debugged and maintained more easily and safely, but traditionally have had much worse performance. We de- scribe a novel Z/O-oriented IPC facility that combines the em- ulated copy data passing scheme for monolithic systems with new copy avoidance techniques for microkernel systems. Un- like previous optimizations, I/O-oriented IPC does not re- quire changes in existing user applications or complex re- structuring of servers; it offers an API with copy semantics and allows the same servers to be installed at kernel or user level. In end-to-end experiments on an ATM network at 512 Mbps, I/O-oriented IPC gave user-level protocol servers performance approaching that of kernel-level ones. Perfor- mance differences scaled roughly inversely to the processor% SPECint95 rating, projecting fast further improvement.","Title: Using physical layer emulation to optimize and evaluate mobile and wireless systems\nYear: 2008\n\nAbstract: Testing and evaluating protocols and applications for wireless networks and mobile users is challenging because the physical environment has a significant impact on the behavior and dynamics of the system. It is however important that these physical world effects are considered during system implementation and evaluation to ensure correct and efficient operation. Unfortunately, since these physical world effects are hard to control and model, this adds considerable complexity to system development. In this paper we show how a wireless networking testbed based on signal propagation emulation was used in the development, testing, and evaluation of mobile systems. The paper is organized as two case studies at different levels of the system: roaming in 802.11 networks and video streaming. We found that the combination of realism and control improved both efficiency and performance during development.","Title: Network Anomaly Detection Using Co-clustering.\nYear: 2012\n\nAbstract: Early Internet architecture design goals did not put security as a high priority. However, today Internet security is a quickly growing concern. The prevalence of Internet attacks has increased significantly, but still the challenge of detecting such attacks generally falls on the end hosts and service providers, requiring system administrators to detect and block attacks on their own. In particular, as social networks have become central hubs of information and communication, they are increasingly the target of attention and attacks. This creates a challenge of carefully distinguishing malicious connections from normal ones. Previous work has shown that for a variety of Internet attacks, there is a small subset of connection measurements that are good indicators of whether a connection is part of an attack or not. In this paper we look at the effectiveness of using two different co-clustering algorithms to both cluster connections as well as mark which connection measurements are strong indicators of what makes any given cluster anomalous relative to the total data set. We run experiments with these co-clustering algorithms on the KDD 1999 Cup data set. In our experiments we find that soft co-clustering, running on samples of data, finds consistent parameters that are strong indicators of anomalous detections and creates clusters, that are highly pure. When running hard co-clustering on the full data set (over 100 runs), we on average have one cluster with 92.44% attack connections and the other with 75.84% normal connections. These results are on par with the KDD 1999 Cup winning entry, showing that co-clustering is a strong, unsupervised method for separating normal connections from anomalous ones. Finally, we believe that the ideas presented in this work may inspire research for anomaly detection in social networks, such as identifying spammers and fraudsters.","Title: Using Architectural Style as a Basis for System Self-repair\nYear: 2002\n\nAbstract: An increasingly important requirement for software systems is the capability to adapt at run time in order to accommodate varying resources, system errors, and changing requirements. For such self-repairing systems, one of the hard problems is determining when a change is needed, and knowing what kind of adaptation is required. Recently several researchers have explored the possibil- ity of using architectural models as a basis for run time monitoring, error de- tection, and repair. Each of these efforts, however, has demonstrated the feasi- bility of using architectural models in the context of a specific style. In this paper we show how to generalize these solutions by making architectural style a parameter in the monitoring/repair framework and its supporting infrastruc- ture. The value of this generalization is that it allows one to tailor monitor- ing/repair mechanisms to match both the properties of interest (such as per- formance or security), and the available operators for run time adaptation.","Title: A conference gateway supporting interoperability between SIP and H.323\nYear: 2001\n\nAbstract: Increased network bandwidth is making desktop video conferencing an attractive application for an increasing number of computer users. Unfortunately, two competing standards for video conferencing signaling are in use, H.323 and SIP. In this paper we look at the interoperability between these two standards by developing a conferencing gateway that supports conferences involving both SIP and H.323 clients. By appropriately translating between H.323 and SIP operations, our prototype gateway supports basic multi-party video conferencing between NetMeeting (an H.323 client) and VIC (a SIP client) without modifications to the clients. However, our experiments also show that seamless interoperation would require changes to the client implementations and the standards.","Title: Software Architecture-Based Adaptation for Pervasive Systems\nYear: 2002\n\nAbstract: An important requirement for pervasive computing systems is the ability to adapt at runtime to handle varying resources, user mobility, changing user needs, and system faults. In this paper we describe an approach in which dynamic adaptation is supported by the use of software architectural models to monitor an application and guide dynamic changes to it. The use of externalized models permits one to make reconfiguration decisions based on a global perspective of the running system, apply analytic models to determine correct repair strategies, and gauge the effectiveness of repair through continuous system monitoring. We illustrate the application of this idea to pervasive computing systems, focusing on the need to adapt based on performance-related criteria and models.","Title: Software architecture-based adaptation for Grid computing\nYear: 2002\n\nAbstract: Grid applications must increasingly self-adapt dynamically to changing environments. In most cases, adaptation has been implemented in an ad hoc fashion, on a per-application basis. This paper describes work which generalizes adaptation so that it can be used across applications by providing an adaptation framework. This framework uses a software architectural model of the system to analyze whether the application requires adaptation, and allows repairs to be written in the context of the architectural model and propagated to the running system. In this paper, we exemplify our framework by applying it to the domain of load-balancing a client-server system. We report on an experiment conducted using our framework, which illustrates that this approach maintains architectural requirements.","Title: Software support for outboard buffering and checksumming\nYear: 1995\n\nAbstract: Data copying and checksumming are the most expensive operations when doing high-bandwidth network IO over a high-speed network. Under some conditions, outboard buffering and checksumming can eliminate accesses to the data, thus making communication less expensive and faster. One of the scenarios in which outboard buffering pays off is the common case of applications accessing the network using the Berkeley sockets interface and the Internet protocol stack. In this paper we describe the changes that were made to a BSD protocol stack to make use of a network adaptor that supports outboard buffering and checksumming. Our goal is not only to achieve \"single copy\" communication for application that use sockets, but to also have efficient communication for in-kernel applications and for applications using other networks. Performance measurements show that for large reads and writes the single-copy path through the stack is significantly more efficient than the original implementation.","Title: Access control to people location information\nYear: 2005\n\nAbstract: Ubiquitous computing uses a variety of information for which access needs to be controlled. For instance, a person's current location is a sensitive piece of information that only authorized entities should be able to learn. Several challenges arise in the specification and implementation of policies controlling access to location information. For example, there can be multiple sources of location information. The sources can be within different administrative domains, which might allow different entities to specify policies, and policies need to be flexible. We address these issues in our design of a distributed access control mechanism for a people location system. Our design encodes policies as digital certificates, which enables decentralized storage of policies. We also present an algorithm for the discovery of distributed certificates. Furthermore, we discuss several privacy issues and show how our design addresses them. To show feasibility of our design, we built an example implementation based on SPKI/SDSI certificates. Using measurements, we quantify the influence of access control on query processing time. We also discuss trade-offs between RSA-based and DSA-based signature schemes for digital certificates.","Title: Network-Aware Parallel Computing with Remos\nYear: 1998\n\nAbstract: Networked systems provide a cost-effective platform for parallel computing, but the applications have to deal with the changing availability of computation and communication resources. Network-awareness is a recent attempt to bridge the gap between the realities of networks and the demands of applications. Network-aware applications obtain information about their execution environment and dynamically adapt to enhance their performance. Adaptation is especially important for synchronous parallel applications since a single busy communication link can become the bottleneck and degrade overall performance dramatically. This paper presents Remos, a uniform API that allows applications to obtain relevant network information, and reports on the development of parallel applications in this environment. The challenges in defining a uniform interface include network heterogeneity, diversity and variability in network traffic, and resource sharing in the network and even inside an application. The first implementation of the Remos system is hosted on an IP-based network testbed. The paper reports on our methodology for developing adaptive parallel applications for high-speed networks with Remos, and presents results that highlight the importance and effectiveness of adaptive parallel computing.","Title: Adaptive Distributed Applications on Heterogeneous Networks\nYear: 1999\n\nAbstract: Distributed applications execute in environments that can include different network architectures as well as a range of compute platforms. Furthermore, these resources are shared by many users. Therefore these applications receive varying levels of service from the environment. Since the availability of resources in a networked environment often determines overall application performance, adaptivity is necessary for efficient execution and predictable response time. However, heterogeneous systems pose many challenges for adaptive applications. We discuss the range of situations that can benefit from adaptivity in the context of a set of system and environment parameters. Adaptive applications require information about the status of the execution environment and heterogeneous environments call for a portable system to provide such information. We discuss Remos (Resource Monitoring System), a system that allows applications to collect information about network and host conditions across different network architectures. Finally, we report our experience and performance results from a set of adaptive versions of Airshed pollution modeling application executing on a networking testbed.","Title: A bandwidth advisor for wireless networks\nYear: 2002\n\nAbstract: Many network intensive applications can benefit substantially from reasonable estimates of future available bandwidth. As a simple example, consider a user, John, that is about to board a flight that is leaving shortly. Using his palmtop equipped with the Aura ubiquitous computing system, John has just finished editing some very large documents that he needs to email over the airport's wireless network. Just before he begins transmission, a 747 begins deplaning passengers at a gate adjacent to where John is waiting; these deplaning passengers are heavily loading the network in John's cell. John's Aura client contacts the bandwidth advisor and learns that there is insufficient bandwidth for John to complete his transmission before his plane leaves. Fortunately, Aura learns from the bandwidth advisor that a nearby cell has ample bandwidth which enables John to move into that cell briefly and complete his transmission before catching his plane.The utility of bandwidth advisors has lead to efforts such as Remos and the Network Weather Service which have investigated providing bandwidth advice in wired network settings. This research builds on this previous work by developing a bandwidth advisor that is specifically tuned for wireless networks, and is suited to the needs of mobile applications.","Title: A simple mechanism for capturing and replaying wireless channels\nYear: 2005\n\nAbstract: Physical layer wireless network emulation has the potential to be a powerful experimental tool. An important challenge in physical emulation, and traditional simulation, is to accurately model the wireless channel. In this paper we examine the possibility of using on-card signal strength measurements to capture wireless channel traces. A key advantage of this approach is the simplicity and ubiquity with which these measurements can be obtained since virtually all wireless devices provide the required metrics. We show that for low delay spread environments wireless traces gathered using this method can be replayed in a physical wireless emulator to produce higher layer network behavior that is similar to the behavior that would have occurred in the real world. Thus, wireless channel traces gathered using on-card metrics are an effective means of enabling existing low delay spread wireless testbeds to be emulated.","Title: Implementing access control to people location information\nYear: 2004\n\nAbstract: Ubiquitous computing uses a variety of information for which access needs to be controlled. For instance, a person's current location is asensitive piece of information, which only authorized entities should be able to learn. Several challenges arise in the specification and implementation of policies controlling access to location information. For example, there can be multiple sources of location information, the sources can be within different administrative domains, different administrative domains might allow different entities to specify policies, and policies need to be flexible. Weaddress these issues in our design of an access control mechanism for a people location system. Our design encodes policies as digital certificates. We present an example implementation based on SPKI/SDSI certificates. Using measurements, we quantify the influence of access control on query processing time. We also discuss trade-offs between RSA-based and DSA-based signature schemes for digital certificates.","Title: Design, implementation and evaluation of an efficient opportunistic retransmission protocol\nYear: 2009\n\nAbstract: This paper presents an efficient opportunistic retransmission protocol (PRO, Protocol for Retransmitting Opportunistically) to improve the performance of IEEE 802.11 WLANs. PRO is a link-layer protocol that allows overhearing nodes to function as relays that retransmit on behalf of the source after they learn about a failed transmission. Relays with stronger connectivity to the destination have a higher chance of delivering the packet than the source does, thereby resulting in a more efficient use of the channel. PRO has four main features. First, channel reciprocity coupled with a run-time calibration process is used to estimate the instantaneous link quality to the destination. Second, a local qualification process filters out poor relays early. Third, a distributed relay selection algorithm chooses the best set of eligible relays among all qualified relays and prioritizes them. Finally, 802.11e Enhanced Distributed Channel Access (EDCA) is leveraged to make sure high priority relays transmit with high probability. PRO is designed to coexist with legacy 802.11 stations. We have implemented PRO in the driver of a commodity wireless card. Our extensive evaluation on both a controlled testbed and in the real world shows that PRO boosts throughput in diverse wireless environments, and especially in when there is significant contention for the channels, under fading, and with user mobility.","Title: Design, implementation, and evaluation of a single-copy protocol stack\nYear: 1998\n\nAbstract: Data copying and checksumming are the most expensive operations on hosts performing high-bandwidth network I/O over a high-speed network, Under some conditions, outboard buffering and checksumming can eliminate accesses to the data, thus making communication less expensive and faster. One of the scenarios in which outboard buffering and checksumming pays off is the common case of applications accessing the network using the Berkeley sockets interface and the Internet protocol stack. In this paper, we describe the host software for a host interface with outboard buffering and checksumming support. The platform used is DEC Alpha workstations with a Turbochannel I/O bus and running the DEC OSF/1 operating system. Our implementation does not only achieve 'single copy' communication for applications that use sockets, but it also interoperates efficiently with in-kernel applications and other network devices. Measurements show that for large reads and writes the single-copy path through the stack is five to seven times more efficient than the traditional implementation. We also present a detailed analysis of the measurements using a simple I/O model. (C) 1998 John Wiley & Sons, Ltd.","Title: Exploiting information relationships for access control in pervasive computing\nYear: 2006\n\nAbstract: Many information services in pervasive computing offer rich information, which is information that includes other types of information. For example, the information listed in a person’s calendar entry can reveal information about the person’s location or activity. To avoid rich information from leaking its included information, we must consider the semantics of the rich information when controlling access to this information. Other approaches that reason about the semantics of information (e.g., based on Semantic Web rule engines) are based on a centralized design, whose drawback is a single point of failure. In this paper, we exploit information relationships for capturing the semantics of information. We identify three types of information relationships that are common and important in pervasive computing and integrate support for them in a distributed, certificate-based access control architecture. In the architecture, individuals can either define their own information relationships or refer to relationships defined by a standardization organization. In our approach, access control is fully distributed while sophisticated rule engines can still be used to deal with more complex access control cases. To demonstrate the feasibility of our design, we give a complexity analysis of the architecture and a performance analysis of a prototype implementation.","Title: CHARQ: Cooperative Hybrid ARQ for wireless video streaming\nYear: 2009\n\nAbstract: Forward error correction (FEC) coding and automatic repeat request (ARQ) are two commonly used techniques to tackle packet erasures in wireless video streaming. To preserve flexibility while reducing end-to-end latency, hybrid ARQ (HARQ) has been proposed as an alternative that combines the advantages of FEC and ARQ. This paper presents cooperative hybrid ARQ (CHARQ) that can further boost wireless video streaming quality. CHARQ takes advantage of the fact that, in the wireless environment, broadcast is free (from the sender's point of view) and that errors are location dependent so an intermediate proxy that overhears the source's transmission may transmit on behalf of the source to increase throughput efficiency. Simulation results show improved performance with the aid of cooperative proxies.","Title: Efficient channel-aware rate adaptation in dynamic environments\nYear: 2008\n\nAbstract: Increasingly, 802.11 devices are being used by mobile users. This results in very dynamic wireless channels that are difficult to use efficiently. Current rate selection algorithms are dominated by probe-based approaches that search for the best transmission rate using trial-and-error. In mobile environments, probe-based techniques often perform poorly because they inefficiently search for the moving target presented by the constantly changing channel. We have developed a channel-aware rate adaptation algorithm CHARM - that uses signal strength measurements collected by the wireless cards to help select the transmission rate. Moreover, unlike previous approaches CHARM leverages channel reciprocity to obtain channel information, so the information is available to the transmitter without incurring RTS/CTS overhead. This combination of techniques allows CHARM to respond quickly to dynamic channel changes. We implemented CHARM in the Madwifi driver for wireless cards using the Atheros chipset. Our evaluation both in the real world and on a controlled testbed shows that channel-aware rate selection can significantly outperform probe-based rate adaptation, especially over dynamic channels.","Title: A Signaling Protocol For Structured Resource Allocation\nYear: 1999\n\nAbstract: There is an emerging class of multi-party, multimedia, multi-dow applications that have a high-level structure that imposes dependencies between resource allocations for flows within the application. These applications are also capable of making intelligent decisions on how resource allocation should be controlled within the application. The development of such applications places new requirements on signaling protocols. This paper outlines these new requirements, discusses ways in which they can be supported and presents the design and implementation of an experimental signaling protocol that supports these requirements.This paper makes the case that for these structured applications, there is an advantage to allocating the resources in an integrated fashion, i.e computation, storage and communication resources for all the Rows are allocated at the same time in a coordinated fashion. The concept of a virtual mesh is introduced as a key abstraction that encapsulates the set of resources that are allocated and managed in an integrated fashion to meet the needs of applications. The paper presents two mesh setup algorithms and a performance evaluation comparing them. Temporal resource sharing within the virtual mesh is discussed in detail and signaling support for temporal sharing at setup and runtime is examined. It is important to characterize temporal sharing since it can significantly reduce the resource requirements for applications.We have implemented the Beagle signaling protocol that supports this integrated resource management model. Beagle representations and mechanisms for mesh setup and temporal sharing are described and a prototype implementation is presented.","Title: Routing high-bandwidth traffic in max-min fair share networks\nYear: 1996\n\nAbstract: We study how to improve the throughput of high-bandwidth traffic such as large file transfers in a network where resources are fairly shared among connections. While it is possible to devise priority or reservation-based schemes that give high-bandwidth traffic preferential treatment at the expense of other connections, we focus on the use of routing algorithms that improve resource allocation while maintaining max-min fair share semantics. In our approach, routing is closely coupled with congestion control in the sense that congestion information, such as the rates allocated to existing connections, is used by the routing algorithm. To reduce the amount of routing information that must be distributed, an abstraction of the congestion information is introduced. Using an extensive set of simulation, we identify a link-cost or cost metric for \"shortest-path\" routing that performs uniformly better than the minimal-hop routing and shortest-widest path routing algorithms. To further improve throughput without reducing the fair share of single-path connections, we propose a novel prioritized multi-path routing algorithm in which low priority paths share the bandwidth left unused by higher priority paths. This leads to a conservative extension of max-min fairness called prioritized multi-level max-min fairness. Simulation results confirm the advantages of our multi-path routing algorithm.","Title: When are directional antennas useful in indoor environments\nYear: 2011\n\nAbstract: Directional antenna systems can provide two benefits 1) improve signal strength and increase communication range, and 2) improve spatial reuse. Recent work has drawn contradicting conclusions in terms of which of the two benefits dominates in indoor environments. These contradicting conclusions are in fact caused by different levels of contention within the environments used in these studies, i.e., noise-dominated vs. interference-dominated. In this paper, we first show that due to emerging applications and technologies, wireless networks are becoming interference-dominated, and thus the ability of the directional antennas to improve spatial reuse is becoming critical. Evaluating the benefits of spatial reuse, however, is difficult especially in indoor environments where multipath have both good and bad effect on spatial reuse. In this paper, we use the separation metric to estimate the effectiveness of directional transmission and guide the placement of directional APs in any particular environment. The separation metric summarizes both the angular and the distance separation for a collection of transmissions in a particular environment. We show that this metric, though simple, is powerful enough to capture the various properties of the deployment and the potential interactions among the directional transmissions. Our experimental results show in several scenarios that the separation metric works well in practice.","Title: Automatic Selection Of Load Balancing Parameters Using Compile-Time And Run-Time Information\nYear: 1997\n\nAbstract: Clusters of workstations are emerging as an important architecture. Programming tools that aid in distributing applications on workstation clusters must address problems of mapping the application, heterogeneity and maximizing system utilization in the presence of varying resource availability. Both computation and communication capabilities may vary with time due to other applications competing for resources, so dynamic load balancing is a key requirement. For greatest benefit, the tool must support a relatively wide class of applications running on clusters with a range of computation and communication capabilities. We have developed a system that supports dynamic load balancing of distributed applications consisting of parallelized DOALL and DOACROSS loops. The focus of the paper is on how the system automatically determines key load balancing parameters using run-time information and information provided by programming tools such as a parallelizing compiler. The parameters discussed are the grain size of the application, the frequency of load balancing, and the parameters that control work movement. Our results are supported by measurements on an implementation for the Nectar system at Carnegie Mellon University and by simulation. (C) 1997 by John Wiley & Sons, Ltd.","Title: Design and Evaluation of a Hybrid Physical Space Service for Pervasive Computing Applications\nYear: 2007\n\nAbstract: In this paper we present the design and implementation of a space service that gives pervasive computing applications both a hierarchical and coordinate-based view of physical space. The space service supports both indoor and outdoor campus environments and, besides relational and coordinate space information, it also gives information on how spaces are connected and relevant properties of spaces. We also evaluate the effectiveness of our design using a set of diverse applications, including finding the best \"walking\" path between two locations, giving walking directions to people, WiFi-based localization, and drawing and annotating maps. We have found that all of our applications depend on both the hierarchical and coordinate views offered by the service, suggesting that the hybrid space model is a very powerful paradigm.","Title: Protecting Access to People Location Information\nYear: 2003\n\nAbstract: Ubiquitous computing provides new types of information for which access needs to be controlled. For instance, a person's current location is a sensitive piece of information, and only authorized entities should be able to learn it. We present several challenges that arise for the specification and implementation of policies controlling access to location information. For example, there can be multiple sources of location information, policies need to be flexible, conflicts between policies might occur, and privacy issues need to be taken into account. Different environments handle these challenges in a different way. We discuss the challenges in the context of a hospital and a university environment. We show how our design of an access control mechanism for a system providing people location information addresses the challenges. Our mechanism can be deployed in different environments. We demonstrate feasibility of our design with an example implementation based on digital certificates.","Title: Locating internet bottlenecks: algorithms, measurements, and implications\nYear: 2004\n\nAbstract: The ability to locate network bottlenecks along end-to-end paths on the Internet is of great interest to both network operators and researchers. For example, knowing where bottleneck links are, network operators can apply traffic engineering either at the interdomain or intradomain level to improve routing. Existing tools either fail to identify the location of bottlenecks, or generate a large amount of probing packets. In addition, they often require access to both end points. In this paper we present Pathneck, a tool that allows end users to efficiently and accurately locate the bottleneck link on an Internet path. Pathneck is based on a novel probing technique called Recursive Packet Train (RPT) and does not require access to the destination. We evaluate Pathneck using wide area Internet experiments and trace-driven emulation. In addition, we present the results of an extensive study on bottlenecks in the Internet using carefully selected, geographically diverse probing sources and destinations. We found that Pathneck can successfully detect bottlenecks for almost 80% of the Internet paths we probed. We also report our success in using the bottleneck location and bandwidth bounds provided by Pathneck to infer bottlenecks and to avoid bottlenecks in multihoming and overlay routing.","Title: Rainbow: Architecture-Based Self-Adaptation with Reusable Infrastructure\nYear: 2004\n\nAbstract: Software-based systems today operate in changing environments and are subject to increasing administrative overhead. To reduce these costs, systems must dynamically self-adapt to accommodate resource variability, user needs, and system faults. The existing internal mechanisms that supportself-adaptation are often highly specific to the application and tightly bound to the code.In principle, external control mechanisms are more effective for self-adaptation because they localize the concerns of problem detection and resolution in separable modules that can be analyzed, modified, extended, and reused across different systems. The Rainbow framework adopts an architecture-based approach to provide a reusable infrastructure and mechanisms for specializing the infrastructure to the needs of specific systems.","Title: Rainbow: architecture-based self-adaptation with reusable infrastructure\nYear: 2004\n\nAbstract: Software-based systems today are increasingly expected to dynamically self-adapt to accommodate resource variability, changing user needs, and system faults. Recent work uses closed-loop control based on external models to monitor and adapt system behavior at run time. Taking this externalized approach, the Rainbow framework we have developed uses software architectural models to dynamically monitor and adapt a running system. A key goal and primary challenge of this framework is to support the reuse of adaptation strategies and infrastructure across different systems. We show that the separation of a generic adaptation infrastructure from system-specific adaptation knowledge makes this reuse possible.","Title: Exploiting internet route sharing for large scale available bandwidth estimation\nYear: 2005\n\nAbstract: Recent progress in active measurement techniques has made it possible to estimate end-to-end path available bandwidth. However, how to efficiently obtain available bandwidth information for the N2 paths in a large N-node system remains an open problem. While researchers have developed coordinate-based models that allow any node to quickly and accurately estimate latency in a scalable fashion, no such models exist for available bandwidth. In this paper we introduce BRoute--a scalable available bandwidth estimation system that is based on a route sharing model. The characteristics of BRoute are that its overhead is linear with the number of end nodes in the system, and that it requires only limited cooperation among end nodes. BRoute leverages the fact that most Internet bottlenecks are on path edges, and that edges are shared by many different paths. It uses AS-level source and sink trees to characterize and infer path-edge sharing in a scalable fashion. In this paper, we describe the BRoute architecture and evaluate the performance of its components. Initial experiments show that BRoute can infer path edges with an accuracy of over 80%. In a small case study on Planetlab, 80% of the available bandwidth estimates obtained from BRoute are accurate within 50%.","Title: Catnap: exploiting high bandwidth wireless interfaces to save energy for mobile devices\nYear: 2010\n\nAbstract: Energy management is a critical issue for mobile devices, with network activity often consuming a significant portion of the total system energy. In this paper, we propose Catnap, a system that reduces energy consumption of mobile devices by allowing them to sleep during data transfers. Catnap exploits high bandwidth wireless interfaces -- which offer significantly higher bandwidth compared to available bandwidth across the Internet -- by combining small gaps between packets into meaningful sleep intervals, thereby allowing the NIC as well as the device to doze off. Catnap targets data oriented applications, such as web and file transfers, which can afford delay of individual packets as long as the overall transfer times do not increase. Our evaluation shows that for small transfers (128kB to 5MB), Catnap allows the NIC to sleep for up to 70% of the total transfer time and for larger transfers, it allows the whole device to sleep for a significant fraction of the total transfer time. This results in battery life improvement of up to 2-5x for real devices like Nokia N810 and Thinkpad T60.","Title: Airshed pollution modeling in an HPF style environment\nYear: 2000\n\nAbstract: In this paper, we describe our experience with developing Airshed, a large pollution modeling application, in the Fx programming environment. We demonstrate that high level parallel programming languages like Fx and High Performance Fortran offer a simple and attractive model for developing portable and efficient parallel applications. Performance results are presented for the Airshed application executing on Intel Paragon and Cray T3D and T3E parallel computers. The results demonstrate that the application is \"performance portable\", i.e., it achieves good and consistent performance across different architectures, and that the performance can be explained and predicted using a simple model for the communication and computation phases in the program. We also show how task parallelism was used to alleviate I/O related bottlenecks, an important consideration in many applications. Finally, we demonstrate how external parallel modules developed using different parallelization methods can be integrated in a relatively simple and flexible way with modules developed in the Fx compiler framework. Overall, our experience demonstrates that a high level parallel programming environment based on a language like HPF is suitable for developing complex multidisciplinary applications.","Title: Access control to information in pervasive computing environments\nYear: 2003\n\nAbstract: Many types of information available in a pervasive computing environment, such as people location information, should be accessible only by a limited set of people. Some properties of the information raise unique challenges for the design of an access control mechanism: Information can emanate from more than one source, it might change its nature or granularity before reaching its final receiver, and it can flow through nodes administrated by different entities. We propose three design principles for the architecture of an access control mechanism: (1) extract pieces of information in raw data streams early, (2) define policies controlling access at the information level, and (3) exploit information relationships for access control. We describe an example architecture in which we apply these principles. We also report how our earlier work about adding access control to a people location service contributed to the more general access control architecture proposed here.","Title: Network-Scale Emulation Of General Wireless Channels\nYear: 2011\n\nAbstract: This paper presents a framework for signal-level emulation of propagation effects over generalized fading channels at the scale of entire networks. Network emulation enables research into network-scale systems - which would otherwise be limited to low-fidelity network simulators and one-off field experiments - to use real radio hardware and realistic channel models. Our hardware and software architecture goes beyond previous work in that it supports real-time emulation of a very general and parametric class of channels, which includes vehicular (broadband mobile-to-mobile) and indoor channels in addition to classical stationary-to-mobile and stationary-to-stationary channels.","Title: Avoiding Privacy Violations Caused by Context-Sensitive Services\nYear: 2006\n\nAbstract: The increasing availability of information about people's context makes it possible to deploy context-sensitive services, where access to resources provided or managed by a service is limited depending on a person's context. For example, a location-based service can require an individual to be at a particular location in order to let the individual use a printer or learn her friends' location. However, constraining access to a resource based on confidential information about a person's context could result in privacy violations. For instance, if access is constrained based on a person's location, granting or rejecting access will provide information about this person's location and could violate the person's privacy. We introduce an access-control algorithm that avoids privacy violations caused by context-sensitive services. Our algorithm exploits the concepts of access-rights graphs, which represent all the information that needs to be collected in order to make a context-sensitive access decision. Moreover, we introduce hidden constraints, which keep some of this information secret and thus allow for more flexible access control. We present a distributed, certificate-based access-control architecture for context-sensitive services that avoids privacy violations, a sample implementation, and a performance evaluation","Title: Analysis of the reputation system and user contributions on a question answering website: StackOverflow\nYear: 2013\n\nAbstract: Question answering (Q&A) communities have been gaining popularity in the past few years. The success of such sites depends mainly on the contribution of a small number of expert users who provide a significant portion of the helpful answers, and so identifying users that have the potential of becoming strong contributers is an important task for owners of such communities. We present a study of the popular Q&A website StackOverflow (SO), in which users ask and answer questions about software development, algorithms, math and other technical topics. The dataset includes information on 3.5 million questions and 6.9 million answers created by 1.3 million users in the years 2008--2012. Participation in activities on the site (such as asking and answering questions) earns users reputation, which is an indicator of the value of that user to the site. We describe an analysis of the SO reputation system, and the participation patterns of high and low reputation users. The contributions of very high reputation users to the site indicate that they are the primary source of answers, and especially of high quality answers. Interestingly, we find that while the majority of questions on the site are asked by low reputation users, on average a high reputation user asks more questions than a user with low reputation. We consider a number of graph analysis methods for detecting influential and anomalous users in the underlying user interaction network, and find they are effective in detecting extreme behaviors such as those of spam users. Lastly, we show an application of our analysis: by considering user contributions over first months of activity on the site, we predict who will become influential long-term contributors.","Title: Effects of buffering semantics on I/O performance\nYear: 1996\n\nAbstract: No abstract available.","Title: A time-based adaptive retry strategy for video streaming in 802.11 WLANs\nYear: 2007\n\nAbstract: Video streaming over time-varying, error-prone wireless LANs (WLANs) poses many challenges. One problem is that WLANs are designed without awareness of the characteristics of application data, which causes performance degradation in a noisy or congested environment. In this paper, we propose a time-based adaptive retry (TAR) mechanism for MPEG-like video streaming over 802.11 wireless networks. TAR dynamically determines whether to send or discard a packet based on its retransmission deadline instead of adopting a static retry limit uniformly over all the packets. Our approach can adapt the retry limit for each individual packet, thus providing indirect unequal error protection over different types of video frames. Analytical and simulation results show that TAR significantly improves video quality and saves channel bandwidth. We also describe a preliminary software-based implementation of TAR and use it to demonstrate the practicality of the proposed approach. Copyright (c) 2007 John Wiley & Sons, Ltd.","Title: Securing information gateways with derivation-constrained access control\nYear: 2006\n\nAbstract: In pervasive computing environments, information gateways derive specific information, such as a person's location, from raw data provided by a service, such as a videostream offered by a camera. Here, access control to confidential raw data provided by a service becomes difficult when a client does not have access rights to this data. For example, a client might have access to a person's location information, but not to the videostream from which a gateway derives this information. Simply granting access rights to a gateway will allow an intruder into the gateway to access any raw data that the gateway can access. We present the concept of derivation-constrained access control, which requires a gateway to prove to a service that the gateway needs requested raw data to answer a client's authorized request for derived information. Therefore, an intruder into the gateway will be limited in its capabilities. We provide a formal framework for derivation-constrained access control based on Lampson et al.'s “speaks-for” relationship. We demonstrate feasibility of our design with a sample implementation and a performance evaluation.","Title: Network-Based Multicomputers: A Practical Supercomputer Architecture\nYear: 1996\n\nAbstract: Multicomputers built around a general network are an attractive architecture for a wide class of applications. The architecture provides many benefits compared with special-purpose approaches, including heterogeneity, reuse of application and system code, and sharing of resources. The architecture also poses new challenges to both computer system implementors and users. First, traditional local-area networks do not have enough bandwidth and create a communication bottleneck, thus seriously limiting the set of applications that can be run effectively. Second, programmers have to deal with large bodies of code distributed over a variety of architectures, and work in an environment where both the network and nodes are shared with other users. Our experience in the Nectar project shows that it is possible to overcome these problems. We show how networks based on high-speed crossbar switches and efficient protocol implementations can support high bandwidth and low latency communication while still enjoying the flexibility of general networks, and we use three applications to demonstrate that network-based multicomputers are a practical architecture. We also show how the network traffic generated by this new class of applications poses severe requirements for networks.","Title: Network-based multicomputers: an emerging parallel architecture\nYear: 1991\n\nAbstract: No abstract available","Title: XIA: efficient support for evolvable internetworking\nYear: 2012\n\nAbstract: Motivated by limitations in today's host-centric IP network, recent studies have proposed clean-slate network architectures centered around alternate first-class principals, such as content, services, or users. However, much like the host-centric IP design, elevating one principal type above others hinders communication between other principals and inhibits the network's capability to evolve. This paper presents the eXpressive Internet Architecture (XIA), an architecture with native support for multiple principals and the ability to evolve its functionality to accommodate new, as yet unforeseen, principals over time. We describe key design requirements, and demonstrate how XIA's rich addressing and forwarding semantics facilitate flexibility and evolvability, while keeping core network functions simple and efficient. We describe case studies that demonstrate key functionality XIA enables.","Title: Robust wireless video streaming using hybrid spatial/temporal retransmission\nYear: 2010\n\nAbstract: Bandwidth demands and timing constraints are two major challenges for wireless video streaming applications. In this paper, we present a hybrid spatial/temporal retransmission protocol that tackles both of these challenges. To increase individual throughput as well as overall network capacity, the system uses an opportunistic retransmission protocol (PRO, Protocol for Retransmitting Opportunistically) that relies on overhearing nodes distributed in physical space to function as relays that retransmit failed packets on behalf of the source. Specifically, the best relay out of the set of nodes that currently have the copy of the packet is responsible for retransmitting (relaying) the packet. Relays with stronger connectivity to the destination have a higher chance of delivering packets successfully than the source, thereby resulting in a more efficient use of the channel. To meet timing constraints, a Time-based Adaptive Retransmission strategy (TAR) is applied by both the source and the relays. With TAR, the MAC dynamically determines whether to (re)transmit or discard a packet based on the retransmission deadline of the packet assigned by the video server. This significantly reduces the number of late packet arrivals at the receiver. Our extensive evaluation results both on a testbed and in the real world demonstrate that hybrid temporal/spatial retransmission can boost streaming performance in diverse wireless environments. The benefits are most pronounced for busy networks, under fading conditions, or for mobile users.","Title: Architecting for edge diversity: supporting rich services over an unbundled transport\nYear: 2012\n\nAbstract: The end-to-end nature of today's transport protocols is increasingly being questioned by the growing heterogeneity of networks and devices, and the need to support in-network services. To address these challenges, we present Tapa, a transport architecture that systematically combines two concepts. First, it unbundles today's transport such that network specific functions (e.g., congestion control) are implemented on a per-segment basis, where a segment spans a part of the end-to-end path that is homogeneous (e.g., wired Internet or an access network) while functions that relate to application semantics (e.g., data ordering) are still implemented end-to-end. Second, it has an explicit notion of in-network services (e.g., caching, opportunistic content retrieval, etc) that can be supported while maintaining precise end-to-end application semantics. In this paper, we present the basic design, implementation and evaluation of Tapa. We also present diverse case studies that show how Tapa can easily support opportunistic content retrieval in online social networks, various mobile and wireless optimizations, and an in-network energy saving service that improves battery life of mobile devices.","Title: Measurement and analysis of the error characteristics of an in-building wireless network\nYear: 1996\n\nAbstract: There is general belief that networks based on wireless technologies have much higher error rates than those based on more traditional technologies such as optical fiber, coaxial cable, or twisted pair wiring. This difference has motivated research on new protocol suites specifically for wireless networks. While the error characteristics of wired networks have been well documented, less experimental data is available for wireless LANs.In this paper we report the results of a study characterizing the error environment provided by AT&T WaveLAN, a commercial product designed for constructing 2 Mb/s in-building wireless networks. We evaluated the effects of interfering radiation sources, and of attenuation due to distance and obstacles, on the packet loss rate and bit error rate. We found that under many conditions the error rate of this physical layer is comparable to that of wired links. We analyze the implications of our results on today's CSMA/CA based wireless LANs and on future pico-cellular shared-medium reservation-based wireless networks.","Title: Enabling MAC protocol implementations on software-defined radios\nYear: 2009\n\nAbstract: Over the past few years a range of new Media Access Control (MAC) protocols have been proposed for wireless networks. This research has been driven by the observation that a single one-size-fits-all MAC protocol cannot meet the needs of diverse wireless deployments and applications. Unfortunately, most MAC functionality has traditionally been implemented on the wireless card for performance reasons, thus, limiting the opportunities for MAC customization. Software-defined radios (SDRs) promise unprecedented flexibility, but their architecture has proven to be a challenge for MAC protocols. In this paper, we identify a minimum set of core MAC functions that must be implemented close to the radio in a high-latency SDR architecture to enable high performance and efficient MAC implementations. These functions include: precise scheduling in time, carrier sense, backoff, dependent packets, packet recognition, fine-grained radio control, and access to physical layer information. While we focus on an architecture where the bus latency exceeds common MAC interaction times (tens to hundreds of microseconds), other SDR architectures with lower latencies can also benefit from implementing a subset of these functions closer to the radio. We also define an API applicable to all SDR architectures that allows the host to control these functions, providing the necessary flexibility to implement a diverse range of MAC protocols. We show the effectiveness of our split-functionality approach through an implementation on the GNU Radio and USRP platforms. Our evaluation based on microbenchmarks and end-to-end network measurements, shows that our design can simultaneously achieve high flexibility and high performance.","Title: Using commodity hardware platform to develop and evaluate CSMA protocols\nYear: 2008\n\nAbstract: Developing and evaluating wireless protocols is challenging because it requires flexible network interface hardware, which is not readily available. In this paper, we present FlexMAC, a wireless protocol development and evaluation platform based on commodity hardware. FlexMAC targets CSMA wireless protocols and allows customization of functions such as backoff, retransmission, and packet timing. We describe our implementation of FlexMAC and quantify FlexMAC's precision for 802.11b compared with commercial hardware implementations. The results show that FlexMAC's performance is very close to that of hardware implementations. We also present two case studies that illustrate FlexMAC's flexibility: the use of opportunistic relaying to boost throughput and an investigation of temporal and throughput fairness. We found that FlexMAC is a useful tool for conducting 802.11-style protocol research.","Title: An Adaptive Protocol for Efficient Support of Range Queries in DHT-Based Systems\nYear: 2004\n\nAbstract: In recent years, Distributed Hash Tables (DHTs) have been proposed as a fundamental building block for large scale distributed applications. Important functionalities such as searching have been added to the DHT's basic lookup capability. However, supporting range queries efficiently remains a difficult problem. In this paper, we describe an adaptive mechanism that relies on a logical tree data structure, the Range Search Tree (RST), to support range queries efficiently. Nodes in the RST automatically group registrations based on their values. Queries are decomposed into a small number of sub-queries for efficient resolution. The system dynamically optimizes itself to minimize the registration and query cost based on observed load. The system is fully distributed and avoids bottleneck problems encountered in traditional tree-based systems. Extensive simulation results validate the effectiveness of the system.","Title: Adaptation Models for Network-Aware Distributed Computations\nYear: 1999\n\nAbstract: Network-aware applications actively adapt to the level of service they receive from the network. This allows the application\n to execute well over a diverse set of networks and under a wide range of network conditions. However, network diversity and\n dynamic network conditions make the development of network-aware applications a difficult task, since the developer has to\n be an expert in both the application domain and networking. In this paper we look at a number of network-aware applications\n and identify three adaptation strategies that have proven to be effective. These strategies can be viewed as adapation models\n that capture the essential structure of the adaptation process. Similar to the use of programming models in parallel and distributed\n computing, adaptation models can be used to guide the development of other network-aware applications and they can also form\n the basis for programming support, e.g. middleware, that supports the development of network-aware applications. In this paper\n we describe the three adaptation models, compare their features and applicability, and briefly discuss how these models impact\n the design of middleware that supports network-aware applications.","Title: Exploiting Hierarchical Identity-Based Encryption for Access Control to Pervasive Computing Information\nYear: 2005\n\nAbstract: Access control to confidential information in pervasive computing environments is challenging for multiple reasons: First, a client requesting access might not know which access rights are necessary in order to be granted access to the requested information. Second, access control must support flexible access rights that include context-sensitive constraints. Third, pervasive computing environments consist of a multitude of information services, which makes simple management of access rights essential. We discuss the shortcomings of existing access-control schemes that rely on either clients presenting a proof of access to a service or services encrypting information before handing the information over to a client. We propose a proofbased access-control architecture that employs hierarchical identity-based encryption in order to enable services to inform clients of the required proof of access in a covert way, without leaking information. Furthermore, we introduce an encryption-based access-control architecture that exploits hierarchical identity-based encryption in order to deal with multiple, hierarchical constraints on access rights. We present an example implementation of our proposed architectures and discuss the performance of this implementation.","Title: Understanding 802.11 performance in heterogeneous environments\nYear: 2011\n\nAbstract: The availability of unlicensed spectrum coupled with the increasing popularity of wireless communication has given rise to a diverse range of wireless technologies that compete for spectrum. In particular, 802.11 devices face a host of problems such as interference with other 802.11 devices (hidden terminals) as well as with technologies like Bluetooth and ZigBee. Understanding how the medium is utilized and inferring the cause of interference, based on observations from a single wireless node, is hard. Past work has used monitoring infrastructures to detect interference between 802.11 nodes in enterprise networks. In this paper, we try to answer the question: \"how can we enable users to reason about wireless performance variations without requiring elaborate instrumentation and infrastructure support?\". We propose WiMed, a tool that uses only local measurements from commodity 802.11 NICs (at the node being diagnosed) to construct a time map of how the medium is utilized. We have implemented a WiMed prototype using the MadWifi driver for Atheros NICs. Early results show that WiMed is useful and can characterize non-802.11 interference better than existing systems.","Title: The Architecture of the Remos System\nYear: 2001\n\nAbstract: Abstract: Remos provides resource information to distributed applications. Its design goals of scalability, flexibility, and portability are achieved through an architecture that allows components to be positioned across the network, each collecting information about its local network. To collect information from different types of networks and from hosts on those networks, Remos provides several collectors that use different technologies, such as SNMP or benchmarking. By matching the appropriate collector to each particular network environment and by providing an architecture for distributing the output of these collectors across all querying environments, Remos collects appropriately detailed information at each site and distributes this information where needed in a scalable manner. Prediction services are integrated at the user-level, allowing history-based data collected across the network to be used to generate the predictions needed by a particular user. Remos has been implemented and tested in a variety of networks and is in use in a number of different environments.","Title: Future of multi-hopping: from theory to practice\nYear: 2009\n\nAbstract: The research community has been fascinated by the challenges posed by multi-hopping for over a decade, and has produced a number of interesting theoretical results and innovative solutions for many of these challenges. However, despite the plethora of envisioned applications for many multi-hop architectures, e.g. mesh, sensor, and ad-hoc, the reality is that there are only a few real-world success stories involving multi-hopping. The panel plans to discuss how we can move more effectively from theory to practice, and debate whether it is a matter of time for more real-world applications to materialize, or cost-related and other real-world considerations will restrict the use of multi-hopping to only a few specialized applications.","Title: A high-speed network interface for distributed-memory systems: architecture and applications\nYear: 1997\n\nAbstract: Distributed-memory systems have traditionally had great difficulty performing network I/O at rates proportional to their computational power. The problem is that the network interface has to support network I/O for a supercomputer, using computational and memory bandwidth resources similar to those of a workstation. As a result, the network interface becomes a bottleneck. In this article we present an I/O architecture that addresses these problems and supports high-speed network I/O on distributed-memory systems. The key to good performance is to partition the work appropriately between the system and the network interface. Some communication tasks are performed on the distributed-memory parallel system, since it is more powerful and less likely to become a bottleneck than the network interface. Tasks that do not parallelize well are performed on the network interface, and hardware support is provided for the most time-critical operations. This architecture has been implemented for the iWarp distributed-memory system and has been used by a number of applications. We describe this implementaiton, present performance results, and use application examples to validated the main features of the I/O architecture.","Title: FlexMAC: a wireless protocol development and evaluation platform based on commodity hardware\nYear: 2008\n\nAbstract: Developing and evaluating wireless protocols is challenging because it requires flexible network interface hardware, which is not readily available. To reduce the efforts of conducting realistic wireless experiment, we have developed FlexMAC, a wireless protocol development and evaluation platform based on commodity hardware. FlexMAC targets CSMA wireless protocols and allows customization of functions such as backoff, retransmission, and packet timing. In this demo, we will show that FlexMAC is a useful tool for wireless protocol development. We will demonstrate two projects that are developed using FlexMAC, including a software-based 802.11 implementation and an opportunistic relaying protocol in 802.11.","Title: A Host Interface Architecture for High-Speed Networks\nYear: 1992\n\nAbstract: This paper describes a new host interface architecture for high-speed networks operating at 800 of Mbit/second or higher rates. The architecture is targeted to achieve several 100s of Mbit/second application-to-application performance for a wide range of host architectures. The architecture achieves the goal by providing a streamlined execution environment for the entire path between host application and network interface. In particular, a “Communication Accelerator Block” (CAB) is used to minimize data copies, reduce host interrupts, support DMA and hardware checksumming, and control network access. This host architecture is applicable to a large class of hosts with high-speed I/O busses. Two implementations for the 800 Mbit/second HIPPI network are under development. One is for a distributed-memory supercomputer (iWarp) and the other is for a high-performance workstation (DECstation 5000). We describe and justify both implementations. Keyword Codes: B.4.1; C.2.1","Title: Architecture implications of high-speed I/O for distributed-memory computers\nYear: 1994\n\nAbstract: We consider the problem of high-speed I/O for a single application running on multiple nodes of a distributed-memory parallel computer. Our model is that the parallel system is connected to an I/O system that provides the interface between the internal connections of the parallel system and one or more external connections, such as HIPPI links. We identify two primary operations for this I/O system: scattering data from a high speed link across several lower speed links and gathering data from multiple links onto a single high speed link. We show that these core operations are the basis of the I/O system, independent of the relative speeds of the internal and external connections.We identify several architectural features that are critical for supporting high-speed scatter and gather operations. They include flexible routing methods in the parallel system, low overhead communication, and the ability to support multiple data streams in and out of the memory on the I/O node.","Title: Video Streaming Over 802.11 WLAN with Content-Aware Adaptive Retry\nYear: 2005\n\nAbstract: Robust video streaming over error-prone wireless LANs (WLANs) poses many challenges. In this paper, we propose a timestamp-based content-aware adaptive retry (CAR) mechanism for MPEG video streaming over 802.11 WLANs, where the MAC dynamically determines whether to send or discard a packet based on its retransmission deadline. The retransmission deadline is assigned to each packet according to its temporal relationship and error propagation characteristics with respect to other video packets in the same GOP. The proposed scheme avoids late packets by eliminating the impact of random backoff deference and co-channel interference with proper initial delay introduced at the receiver. Simulation results show CAR significantly improves video quality and saves channel bandwidth","Title: Adaptive filtering of MPEG system streams in IP networks\nYear: 2006\n\nAbstract: Congestion and large differences in available link bandwidth create challenges for the design of applications that want to deliver high quality video over the Internet. We present an efficient adaptive filter for MPEG System streams that can be placed in the network (e.g., as an active service). This filter adjusts the bandwidth demands of an MPEG System stream to the available bandwidth without transcoding while maintaining synchronization between the streams embedded in the MPEG System. The filter is network-friendly: it is fair with respect to other (TCP) competing streams and it avoids generating bursty traffic. This paper presents the system architecture and an evaluation of our implementation in three different operating environments: a networking testbed in a laboratory environment, a home-user scenario (DSL line with 640 Kbit/s), and a wide area network covering the Atlantic (server in Europe, client in the US). Moreover we examine the network-friendliness of the adaptation protocol and the relationship between the quality of the received continuous media and the protocol's aggressiveness. Our architecture is based on efficient MPEG System filtering to achieve high-quality video over best-effort networks.","Title: RFDump: an architecture for monitoring the wireless ether\nYear: 2009\n\nAbstract: Networking researchers have been using tools like wireshark and tcpdump to sniff packets on physical links that use different types of datalink protocols, e.g. Ethernet or 802.11, allowing them to monitor higher level protocols sharing these links. However, monitoring wireless links is more challenging, since the transmission medium is shared by flows using diverse datalink protocols (e.g. 802.11, Bluetooth) and physical layer schemes (e.g. QPSK and GFSK). To this end, we propose RFDump, a software architecture for monitoring packets on heterogeneous wireless networks. The key idea underlying our architecture is the use of a fast detection stage which can tentatively map signals to protocols very efficiently. As a result, RFDump can scale up to a modest number (5-10) of wireless technologies. We implemented RFDump on the GNU Radio and USRP platforms. This is, to our knowledge, the first inexpensive software-based infrastructure for simultaneously analyzing multiple wireless protocols in real-time. Using traces from the real world and from a wireless emulator testbed, we show that our implementation is efficient and accurate. Further, we demonstrate that our system is extensible and scales with the addition of new protocols.","Title: A trace-based evaluation of adaptive error correction for a wireless local area network\nYear: 1999\n\nAbstract: Wireless transmissions are highly susceptible to noise and interference. As a result, the error characteristics of a wireless link may vary widely depending on environmental factors such as location of the communicating systems and activity of competing radiation sources, making error control a difficult task. In this paper we evaluate error control strategies for a wireless LAN. Based on low-level packet traces of WaveLAN, we first show that forward error correction (FEC) is effective in recovering from bit corruptions and that packet length adjustment can reduce packet truncation. However, as expected, fixed error control policies can perform very poorly, because they either introduce too much overhead in “good” environments or are not aggressive enough in “bad” environments. We address this problem through adaptive error control, i.e., error control policies that adapt the degree of FEC redundancy and the packet size to the environment. The effectiveness of adaptive error control depends on the characteristics of the error environment, e.g., the type of errors and the frequency with which the error environment changes. Our evaluation shows that adaptive error control can improve throughput consistently across a wide range of wireless LAN error environments. The reason for this effectiveness is that changes in the error environemtn are often caused by human mobility-related events such as the motion of a cordless phone, which take place over seconds, while adaptation protocols can respond in tens of milliseconds. Evaluating adaptive error control in a wireless environments is challenging because repeatable experiments are difficult: the wireless environment cannot easily be isolated and the adaptation process itself changes the environment, which may make trace-based evaluation difficult. We introduce a trace-based evaluation methodology that deals appropriately with changes in packet content and size.","Title: Design And Implementation Of An Rf Front End For Physical Layer Wireless Network Emulation\nYear: 2007\n\nAbstract: Networking researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we have developed a wireless network emulator that enables both realistic and repeatable experimentation at network scale. A critical component in this emulator is the RF Front End that converts RF signals to lower frequencies - where they can be digitized - and vice versa.We discuss the unique requirements that physical layer network emulation demands of an RF Front End. We present a design that meets these demands and demonstrate its performance via measurements.","Title: Performance of circuit switched LANs under different traffic conditions\nYear: 1994\n\nAbstract: Switched LANs are become more widely used because they can provide a higher bandwidth than LANs based on shared media. Examples of packet switched LANs include HIPPI, and switched FDDI and Ethernet. A number of studies have evaluated the performance of HIPPI networks, making simplifying assumptions about both the network and the traffic load. In this paper we present the results of a simulation study of circuit-switched LANs such as HIPPI using more realistic models for the system and the traffic. We observe changes in throughput as high as a factor of ten when we change the system and traffic parameters. We also show how packet scheduling can be used to improve performance in some cases","Title: Improving the accuracy of environment-specific vehicular channel modeling\nYear: 2012\n\nAbstract: Networking research benefits from the controlled, repeatable experimentation provided by simulation and emulation systems. Making such simulations realistic is a challenge for wireless systems and is especially difficult for vehicular networks. This paper introduces a realistic vehicular channel simulation model that includes a Line-Of-Sight (LOS) module and Vehicle-to-Vehicle (V2V) fading module specially designed for vehicular channels. Specialized models can provide a close approximation of real channel conditions, but their accuracy is limited by the quality of input information about the environment being modeled. In this paper, we present a systematic approach to estimate location-specific scattering properties using aerial photography. We show that this approach significantly improves the accuracy of simulated channel fading.","Title: Evaluation Of Adaptive Filtering Of Mpeg System Streams In Ip Networks\nYear: 2000\n\nAbstract: Congestion and large differences in available link bandwidth create challenges for the design of applications that want to deliver high quality video over the Internet. We investigate the placement of computation agents within the network to provide filtering to adapt MPEG system streams to the available bandwidth without transcoding. This paper presents an evaluation of our implementation in three different operating environments: a networking testbed in a laboratory environment, a home-user scenario (DSL line with 640 Kbit/sec), and a wide area network covering the Atlantic (server in Europe, client in the US). Our architecture leverages previous work and introduces efficient MPEG system filtering to achieve high-quality video over best-effort networks.","Title: Improving TCP Startup Performance Using Active Measurements: Algorithm and Evaluation\nYear: 2003\n\nAbstract: TCP Slow Start exponentially increases the congestion window size to detect the proper congestion window for a network path. This often results in significant packet loss, while breaking off Slow Start using a limited slow start threshold may lead to an overly conservative congestion window size. This problem is especially severe in high speed networks. In this paper we present a new TCP startup algorithm, called Paced Start, that incorporates an available bandwidth probing technique into the TCP startup algorithm. Paced Start is based on the observation that when we view the TCP startup sequence as a sequence of packet trains, the difference between the data packet spacing and the acknowledgement spacing can yield valuable information about the available bandwidth. Slow Start ignores this information, while Paced Start uses it to quickly estimate the proper congestion window for the path. For most flows, Paced Start transitions into congestion avoidance mode faster thanSlow Start, has a signi.cantly lower packet loss rate, and avoids the timeout that is often associated with Slow Start. This paper describes the Paced Start algorithm and uses simulation and real system experiments to characterize its properties.","Title: Architecture and evaluation of a high-speed networking subsystem for distributed-memory systems\nYear: 1994\n\nAbstract: Achieving high-speed network I/O on distributed-memory systems is difficult because their architecture is in general ill-suited for communication processing. Some of the common problems are: inability to do protocol processing, inefficient handling of data distribution, and poor management of the I/O. The authors present an I/O architecture that addresses these problems and supports high-speed network I/O on distributed-memory systems. The key to good performance is to partition the work appropriately between the system and the network interface. The authors perform some communication tasks on the distributed-memory parallel system since it is more powerful, and less likely to become a bottleneck than the network interface. Tasks that do not parallelize well are performed on the network interface and hardware support is provided for the most time-critical operations. They emphasize the use of simple I/O mechanisms that can be used by programming tools that map applications on the distributed-memory system to implement efficient I/O for the class of applications they support. This architecture has been implemented for the iWarp distributed-memory system. The authors describe this implementation and present performance results","Title: Providing Contextual Information to Pervasive Computing Applications\nYear: 2003\n\nAbstract: Pervasive computing applications are increasingly leveraging contextual information from several sources to provide users with behavior appropriate to the environment in which they reside. If these sources of contextual information are used and deployed in an ad hoc manner, however, they may provide overlapping functionality, fail to provide needed functionality, and require the use of inconsistent interfaces by applications. To overcome these problems, we introduce a Contextual Information Service that provides applications with contextual information via a virtual database. Unlike previous efforts, our service provides applications a consistent, lightweight, and powerful mechanism for obtaining contextual information, and includes explicit support for the on demand computation of contextual information. We show, via example applications and a Contextual Information Service prototype that we have implemented, how this approach can be used to allow proactive applications to adapt their behavior to match a user's current environment.","Title: Time-Aware Opportunistic Relay For Video Streaming Over Wlans\nYear: 2007\n\nAbstract: Robust video streaming over time-varying, error-prone wireless LANs (WLANs) poses many challenges. In this paper, we present a Time-based Opportunistic Relay (TOR) scheme for high-quality video streaming over WLANs. The proposed scheme exploits path diversity in relaying packets with awareness of the time constraints of video data. Specifically, relay nodes continuously overhear and opportunistically forward packets to enhance end-to-end delivery rates. To relay a packet in a time-aware manner, a relay deadline is computed for each packet and used by relay nodes to determine whether they should relay or discard the packet. Simulation results show that TOR improves video quality by up to 9.76 dB.","Title: The use of a controlled wireless testbed in courses\nYear: 2009\n\nAbstract: Wireless networking has become a popular topic in both undergraduate and graduate courses. However, putting together good assignments in wireless networking is difficult because the behavior of the wireless network depends strongly on the physical environment. We have used a wireless networking testbed based on signal propagation emulation in a number of wireless networking courses. The wireless emulator supports highly realistic experiments, while also offering a high degree of control and repeatability. This combination is very useful in a teaching context. In this paper we give an overview of the wireless emulator and we describe how it was used to support assignments and open-ended projects in several courses.","Title: Self-management in chaotic wireless deployments\nYear: 2007\n\nAbstract: Over the past few years, wireless networking technologies have made vast forays into our daily lives. Today, one can find 802.11 hardware and other personal wireless technology employed at homes, shopping malls, coffee shops and airports. Present-day wireless network deployments bear two important properties: they are unplanned, with most access points (APs) deployed by users in a spontaneous manner, resulting in highly variable AP densities; and they are unmanaged, since manually configuring and managing a wireless network is very complicated. We refer to such wireless deployments as being chaotic. In this paper, we present a study of the impact of interference in chaotic 802.11 deployments on end-client performance. First, using large-scale measurement data from several cities, we show that it is not uncommon to have tens of APs deployed in close proximity of each other. Moreover, most APs are not configured to minimize interference with their neighbors. We then perform trace-driven simulations to show that the performance of end-clients could suffer significantly in chaotic deployments. We argue that end-client experience could be significantly improved by making chaotic wireless networks self-managing. We design and evaluate automated power control and rate adaptation algorithms to minimize interference among neighboring APs, while ensuring robust end-client performance.","Title: Can user-level probing detect and diagnose common home-WLAN pathologies\nYear: 2012\n\nAbstract: Common Wireless LAN (WLAN) pathologies include low signal-to-noise ratio, congestion, hidden terminals or interference from non-802.11 devices and phenomena. Prior work has focused on the detection and diagnosis of such problems using layer-2 information from 802.11 devices and special purpose access points and monitors, which may not be generally available. Here, we investigate a user-level approach: is it possible to detect and diagnose 802.11 pathologies with strictly user-level active probing, without any cooperation from, and without any visibility in, layer-2 devices? In this paper, we present preliminary but promising results indicating that such diagnostics are feasible.","Title: Gigabit I/O for distributed-memory machines: architecture and applications\nYear: 1995\n\nAbstract: Distributed-memory systems have traditionally had great difficulty performing network I/O at rates proportional to their computational power. The problem is that the network interface has to support network I/O for a supercomputer, using computational and memory bandwidth resources similar to those of a workstation. As a result, the network interface becomes a bottleneck. We implemented an architecture for network I/O for the iWarp system with the following two key characteristics: first, application-specific tasks are off-loaded from the network interface to the distributed-memory system, and second, these tasks are performed in close cooperation with the application. The network interface has been used by several applications for over a year. In this paper we describe the network interface software that manages the communication between the iWarp distributed-memory system and the network interface, we validate the main features of our network interface architecture based on application experience, and we discuss how this architecture can be used by other distributed-memory systems.","Title: Repeatable and realistic wireless experimentation through physical emulation\nYear: 2004\n\nAbstract: In wireless networking research, there has long existed a fundamental tension between experimental realism on one hand, and control and repeatability on the other hand. Hardware-based experimentation provides realism, but is tightly coupled to the physical environment and circumstances under which experiments are carried out. To overcome this, researchers have understandably embraced simulation as a means of evaluation. Unfortunately, wireless simulation is plagued with inherent inaccuracies. To overcome the stark tradeoff between the realism of hardware-based experimentation and the repeatability of simulation-based experimentation, we are developing a wireless emulator that enables both realistic and repeatable experimentation. Unlike previous emulators, our approach simultaneously achieves both a high degree of realism and fine-grained repeatability by leveraging physical layer emulation.","Title: Characterizing 802.11 wireless link behavior\nYear: 2010\n\nAbstract: Since wireless signals propagate through the ether, they are significantly affected by attenuation, fading, multipath, and interference. As a result, it is difficult to measure and understand fundamental wireless network behavior. This creates a challenge for both network researchers, who often rely on simulators to evaluate their work, and network managers, who need to deploy and optimize operational networks. Given the complexity of wireless networks, both communities often rely on simplifying rules, which frequently have not been validated using today's wireless radios. In this paper, we undertake a detailed characterization of 802.11 link-level behavior using commercial 802.11 cards. Our study uses a wireless testbed that provides signal propagation emulation, giving us complete control over the signal environment. In addition, we use our measurements to analyze the performance of an operational wireless network. Our work contributes to a more accurate understanding of link-level behavior and enables the development of more accurate wireless network simulators.","Title: Reclaiming the white spaces: spectrum efficient coexistence with primary users\nYear: 2011\n\nAbstract: TV white spaces offer an exciting opportunity for increasing spectrum availability, but white space devices (WSDs) cannot interfere with primary users, including TV channels and wireless microphones (mics). Mics are particularly challenging because their use is dynamic and it is hard to avoid interference since mic receivers are receive-only devices. For this reason the FCC and other regulatory agencies have made very conservatives rules that require WSDs to vacate any TV channel that is used by a mic. However, our measurements show that mics typically require only 5% of a channel, wasting as much as 95% of the spectrum. We present SEISMIC, a systems that enables WSDs and mics to operate on the same TV channel with zero audible mic interference. SEISMIC implements a MicProtector to measure the interference at the mic receiver and a signaling protocol to notify the WSD of impending interference. This allows the WSD to optimize its transmission (e.g. through subcarrier suppression) without impacting mics. We motivate and describe SEISMIC and present a detailed performance analysis that shows that SEISMIC can regain up to 95% of the spectrum in single mic scenarios, and up to 85% in many (10+) mic environments.","Title: A scalable peer-to-peer system for music content and information retrieval\nYear: 2003\n\nAbstract: Currently a large percentage of Internet traffic con- sists of music files, typically stored in MP3 com- pressed audio format, shared and exchanged over Peer-to-Peer (P2P) networks. Searching for music is performed by specifying keywords and naive string matching techniques. In the past years the emerging research area of Music Information Retrieval (MIR) has produced a variety of new ways of looking at the problem of music search. Such MIR techniques can significantly enhance the ways user search for music over P2P networks. In order for that to happen there are two main challenges that need to be addressed: 1) scalability to large collections and number of peers, 2) richer set of search semantics that can support MIR especially when retrieval is content-based. In this paper, we describe a scalable P2P system that uses Rendezvous Points (RPs) for music metadata regis- tration and query resolution, that supports attribute- value search semantics as well as content-based re- trieval. The performance of the system has been eval- uated in large scale usage scenarios using \"real\" au- tomatically calculated musical content descriptors.","Title: XIA: an architecture for an evolvable and trustworthy internet\nYear: 2011\n\nAbstract: Motivated by limitations in today's host-based IP network architecture, recent studies have proposed clean-slate network architectures centered around alternative first-class principals, such as content, services, or users. However, much like the host-centric IP design, elevating one principal type above others hinders communication between other principals and inhibits the network's capability to evolve. Our work presents the eXpressive Internet Architecture (XIA), an architecture with native support for multiple principals and the ability to evolve its functionality to accommodate new, as yet unforeseen, principals over time. XIA also provides intrinsic security: communicating entities validate that their underlying intent was satisfied correctly without relying on external databases or configuration. In this paper, we focus on core architectural issues in the XIA data plane. We outline key design requirements relating to native support for multiple principals and intrinsic security. We then use case studies to demonstrate how the XIA design facilitates evolvability and flexibility.","Title: Using emulation to understand and improve wireless networks and applications\nYear: 2005\n\nAbstract: Researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we are developing a wireless emulator that enables both realistic and repeatable experimentation by leveraging physical layer emulation. We discuss the design and implementation of a prototype wireless emulator, and show how this emulator can be leveraged to provide insight into wireless network and application behaviour. Our experience shows that, compared to simulation, our emulator-based approach provides us with a better understanding of real-world wireless network performance, and enables us to quickly deploy our research into an operational wireless network, while still allowing us to enjoy the benefits of a controlled experimental environment.","Title: Fpga-Based Channel Simulator For A Wireless Network Emulator\nYear: 2009\n\nAbstract: Wireless channel emulators are important tools for testing radio devices, especially in mobile environments. Wireless network emulators give the same accuracy and control for testing radio network systems that traditional channel emulators give to point to point radio links. Network emulators require many more independent channels than traditional channel emulators. This problem is particularly challenging for the real time channel simulator in the emulator. The challenges of designing a wireless network channel simulator are discussed and a design is presented on a Xilinx Virtex-II Pro FPGA. This channel simulator can model 210 independent channels between 15 nodes with a bandwidth of 90MHz. The performance of the design was verified by measuring transport-layer throughput between 802.11b radios transmitting through the channel simulator.","Title: A resource query interface for network-aware applications\nYear: 1998\n\nAbstract: Networked systems provide a cost-effective platform for parallel computing, but the applications have to deal with the changing availability of computation and communication resources. Network-awareness is a recent attempt to bridge the gap between the realities of networks and the demands of applications. Network-aware applications obtain information about their execution environment and dynamically adapt to enhance their performance. Adaptation is especially important for synchronous parallel applications because a single busy communication link can become the bottleneck and degrade overall performance dramatically. This paper presents Remos, a uniform API that allows applications to obtain relevant network information, and reports on the development of parallel applications in this environment. The challenges in defining a uniform interface include network heterogeneity, diversity and variability in network traffic, and resource sharing in the network and even inside an application. The first implementation of the Remos interface uses SNMP to monitor IP-based networks. This paper reports on our methodology for developing adaptive parallel applications for high-speed networks with Remos and presents experimental results using applications generated by the Fx parallelizing compiler. The results highlight the importance and effectiveness of adaptive parallel computing.","Title: An Architecture for the Integration of Physical and Informational Spaces\nYear: 2002\n\nAbstract: While computer processing power, storage capacity, and bandwidth are continuing to experience exponential growth, individual human processing capabilities are not increasing significantly. Pervasive computing offers an opportunity for applications to interact with the physical environment and to provide a task-centric and mobile infrastructure for the user. However, this rich environment can also be distracting, in part because of a lack of convergence between the physical infrastructure observed by users and the information space seen by applications. In this paper we introduce AIPIS, an architecture that bridges the physical and informational realms of the human and the computer, respectively. The purpose of AIPIS is two-fold: (1) provide users with a hands-free computing environment that automates much of the drudgery associated with the use of computers; and (2) require human attention for only critical aspects of task execution that require their input. We also describe the Aura desktop, a first prototype of the AIPIS architecture.","Title: A Hybrid Location Model with a Computable Location Identifier for Ubiquitous Computing\nYear: 2002\n\nAbstract: Location modeling and representation are crucial technologies for context-aware applications. In this paper, we present a novel location model combining the virtues of both the hierarchical and coordinate location models, and we introduce a computable location identifier, namely Aura Location Identifier (ALI). We then describe how the Aura space service uses this hybrid model to handle spatial queries for contextaware applications. Asimple example of such a query is a range query, e.g. \"select name from printer where distance(location, 'ali://cmu/wean-hall/floor3/3100-corridor#(10,10,0)')","Title: Undergraduate embedded system education at Carnegie Mellon\nYear: 2005\n\nAbstract: Embedded systems encompass a wide range of applications, technologies, and disciplines, necessitating a broad approach to education. We describe embedded system coursework during the first 4 years of university education (the U.S. undergraduate level). Embedded application curriculum areas include: small and single-microcontroller applications, control systems, distributed embedded control, system-on-chip, networking, embedded PCs, critical systems, robotics, computer peripherals, wireless data systems, signal processing, and command and control. Additional cross-cutting skills that are important to embedded system designers include: security, dependability, energy-aware computing, software/systems engineering, real-time computing, and human--computer interaction. We describe lessons learned from teaching courses in many of these areas, as well as general skills taught and approaches used, including a heavy emphasis on course projects to teach system skills.","Title: Pushing the envelope of indoor wireless spatial reuse using directional access points and clients\nYear: 2010\n\nAbstract: Recent work demonstrates that directional antennas have significant potential to improve wireless network capacity in indoor environments. This paper provides a broader exploration of the design space of indoor directional antenna systems along two main dimensions: antenna configuration and antenna control. Studying a number of alternative configurations, we find that directionality on APs and clients can significantly improve performance, even over other configurations with stronger directionality. Moreover, it is sufficient to have a small number of narrow beam antennas to achieve such gains, thus making such a solution practical for actual deployment. Designing systems with directional APs and clients for increased spatial reuse comes, however, with a number of challenges in the way the directional antennas are controlled. Antenna control needs to encompass antenna orientation algorithms, an appropriate MAC layer protocol, and novel client-AP association solutions. To overcome these challenges, we propose Speed, a distributed directional antenna control system that is easy to deploy and significantly improves network capacity over existing solutions.","Title: A software architecture for physical layer wireless network emulation\nYear: 2006\n\nAbstract: Despite their widespread deployment, many aspects of wireless network performance are poorly understood, and there is great room from improvement in wireless network reliability and performance. A key obstacle to understanding and improving wireless networks has been the lack of a realistic yet flexible experimental methodology. Physical layer wireless network emulation promises to achieve much of the flexibility of wireless simulators while maintaining much of the realism of real wireless networks. We have developed a software architecture that tames the complexity of physical layer wireless network emulation, and presents users with a powerful yet ease-to-use interface. We present several case studies showing how this software architecture allows complex wireless experiments to be conducted in an efficient manner while still enabling novice users to quickly run simple experiments.","Title: Efficient Support for Similarity Searches in DHT-Based Peer-to-Peer Systems\nYear: 2007\n\nAbstract: Distributed hash tables (DHTs) provide a scalable and robust building block for content discovery in distributed applications such as Peer-to-Peer (P2P) systems. However, the basic DHT put/get API only supports simple exact queries. In this paper, we present a DHT-based system that efficiently supports similarity queries on multidimensional datasets. Our system embeds a logical kd-tree into the DHT's identifier space to form a distributed indexing structure, the distributed kd-tree (DKDT). We avoid creating bottlenecks, which are typical in tree- based systems, by relying on fully distributed protocols for tree management and data registrations and queries. We propose tree compressing and node shrinking techniques to efficiently support applications with high dimensionality datasets. Simulation results using both synthetic and real data show the effectiveness of our system.","Title: Supporting the development of network programs\nYear: 1991\n\nAbstract: Programmers who want to do network computing face several challenges: the network and attached systems are shared resources with an unpredictable behavior and network communication primitives are often hard to use. The programming environment developed for the Nectar system addresses both problems. It provides simple and efficient communication primitives, and an efficient monitoring kernel that allows both programmers and programming tools to monitor the behavior of the program in the dynamic network environment. Experience shows that monitoring the progress of applications interactively is both desirable and practical","Title: Understanding link-level 802.11 behavior: replacing convention with measurement.\nYear: 2007\n\nAbstract: Since wireless signals propagate through the ether, they are significantly affected by attenuation, fading, and interference. As a result, it is often difficult to measure and understand fundamental wireless network behavior. This creates a challenge for both network researchers, who often rely on simulators to evaluate their work, and network managers, who need to deploy and optimize operational networks. Given the complexity of wireless networks, both communities often rely on simplifying rules, which often have not been validated using today's wireless radios. In this paper, we undertake a detailed analysis of 802.11 link-level behavior using real hardware and a physical layer wireless network emulator that gives us complete control over signal propagation. We replace conventional assumptions and possible misconceptions with actual recorded behavior. Additionally, we analyze the impact of our observations on commonly deployed networks. Our work contributes to a more accurate understanding of link-level behavior and enables the development of more accurate wireless network simulators.","Title: XIA: architecting a more trustworthy and evolvable internet\nYear: 2014\n\nAbstract: Motivated by limitations in today's host-centric IP network, recent studies have proposed clean-slate network architectures centered around alternate first-class principals, such as content, services, or users. However, muchlike the host-centric IP design, elevating one principal type above others hinders communication between other principals and inhibits the network's capability to evolve. This paper presents the eXpressive Internet Architecture (XIA), an architecture with native support for multiple principals and the ability to evolve its functionality to accommodate new, as yet unforeseen, principals over time. We present the results of our ongoing research motivated by and building on the XIA architecture, ranging from topics at the physical level (``how fast can XIA go'') up through to the user level.","Title: Simulating spatial cross-correlation in vehicular networks\nYear: 2014\n\nAbstract: Wireless channels are defined by the presence and motion of objects between and around the communicating stations. As parts of the environment change, so do the channels between stations that are nearby. While the impact of environmental changes on individual channals has been studies extensively, the spatial autocorrelation across multiple channels, which we will call spatial cross-correlation, has received little attention. These effects are important whenever protocols use multiple channels in real time, such as in multi-hop networks. This paper studies the trade-offs between different ways of simulating spatial channel cross-correlation in the context of vehicular networks. We compare independent stochastic, locally cross-correlated stochastic, and explicitly geometric models in terms of both their complexity and the network-level performance they induce. Our results generally favor the geometric approach. Geometric models have higher precision and lower complexity than cross-correlated stochastic models, although collecting the detailed input needed for geometric models can be expensive. As a result, we propose a hybrid approach that combines geometric and stochastic approaches, depending on whether the impact of physical changes has a major or more minor impact on the channels.","Title: The Cost of the \"S\" in HTTPS.\nYear: 2014\n\nAbstract: Increased user concern over security and privacy on the Internet has led to widespread adoption of HTTPS, the secure version of HTTP. HTTPS authenticates the communicating end points and provides confidentiality for the ensuing communication. However, as with any security solution, it does not come for free. HTTPS may introduce overhead in terms of infrastructure costs, communication latency, data usage, and energy consumption. Moreover, given the opaqueness of the encrypted communication, any in-network value added services requiring visibility into application layer content, such as caches and virus scanners, become ineffective.\n\nThis paper attempts to shed some light on these costs. First, taking advantage of datasets collected from large ISPs, we examine the accelerating adoption of HTTPS over the last three years. Second, we quantify the direct and indirect costs of this evolution. Our results show that, indeed, security does not come for free. This work thus aims to stimulate discussion on technologies that can mitigate the costs of HTTPS while still protecting the user's privacy.","Title: Balancing accountability and privacy in the network\nYear: 2014\n\nAbstract: Though most would agree that accountability and privacy are both valuable, today's Internet provides little support for either. Previous efforts have explored ways to offer stronger guarantees for one of the two, typically at the expense of the other; indeed, at first glance accountability and privacy appear mutually exclusive. At the center of the tussle is the source address: in an accountable Internet, source addresses undeniably link packets and senders so hosts can be punished for bad behavior. In a privacy-preserving Internet, source addresses are hidden as much as possible. In this paper, we argue that a balance is possible. We introduce the Accountable and Private Internet Protocol (APIP), which splits source addresses into two separate fields --- an accountability address and a return address --- and introduces independent mechanisms for managing each. Accountability addresses, rather than pointing to hosts, point to accountability delegates, which agree to vouch for packets on their clients' behalves, taking appropriate action when misbehavior is reported. With accountability handled by delegates, senders are now free to mask their return addresses; we discuss a few techniques for doing so.","Title: Using your smartphone to detect and map heterogeneous networks and devices in the home\nYear: 2014\n\nAbstract: Heterogeneity in the wireless spectrum is an increasing problem which breaks down coordination and exacerbates wireless interference. In particular, this is a growing problem in the home: heterogeneity is increasing, yet there is a lack of tools and expertise in the home to gather the necessary information about its RF environment to combat this issue. In this paper, we present a unique monitoring system design which leverages the smartphone: now commodity, flexible and familiar to the home user, and equipped with multiple heterogeneous for sensing. Our design overcomes challenges inherent to monitoring with the phone (e.g., it is location agnostic without in-door localization) to derive where signals go and what they interfere with. It does so only requiring simple user-interaction, and as we will show, can bring the information to a level the user can understand.","Title: Self-automated parking lots for autonomous vehicles based on vehicular ad hoc networking\nYear: 2014\n\nAbstract: Parking is a major problem of car transportation, with important implications in traffic congestion and urban landscape. Reducing the space needed to park cars has led to the development of fully automated and mechanical parking systems. These systems are, however, limitedly deployed because of their construction and maintenance costs. Leveraging on semi and fully-autonomous vehicular technology, as well as on the electric propulsion paradigm and in vehicular ad hoc networking, we propose a new parking concept where the mobility of parked vehicles is managed by a parking lot controller to create space for cars entering or exiting the parking lot, in a collaborative manner. We show that the space needed to park such vehicles can be reduced to half the space needed with conventional parking lot designs. We also show that the total travelled distance of vehicles in this new parking lot paradigm can be 30% less than in conventional parking lots. Our proposal can have important consequences in parking costs and in urban landscape.","Title: Centralized, measurement-based, spectrum management for environments with heterogeneous wireless networks\nYear: 2014\n\nAbstract: Heterogeneity of wireless networks has become an increasing problem in the wireless spectrum that breaks down spectrum sharing and exacerbates interference. Many coexistence techniques have been proposed to alleviate this interference, however, they are difficult to deploy due to changes needed in the protocols, overhead, and rapid changes in technology. In this paper, we focus on the potential of spectrum management to provide a long-term solution. We introduce novel components to a spectrum management system that overcomes limitations of current models that have remained relatively focused on homogeneous environments. Our approach is a centralized one, where we analyze information collected from heterogeneous monitors available today, structure the information in a hypergraph, and perform an analysis to detect heterogeneous conflicts. Introducing a mixed integer program (in addition to other novel components), we reconfigure devices in the spectrum to avoid conflicts and improve performance.","Title: A general architecture for load balancing in a distributed-memory environment\nYear: 1993\n\nAbstract: The goal of load balancing is to assign to each node a number of tasks proportional to its performance. On distributed-memory machines, it is important to take data dependencies into account when distributing tasks, since they have a big impact on the communication requirements of the distributed application. The authors present a load balancing architecture that can deal with applications with heterogeneous tasks. The idea is to provide a set of load balancers that are effective for different types of homogeneous tasks, and to allow users to combine these load balancers for applications with heterogeneous tasks. This architecture was implemented on the Nectar multicomputer and performance results are presented for several applications with homogeneous and heterogeneous tasks","Title: Data reshuffling in support of fast I/O for distributed-memory machines\nYear: 1994\n\nAbstract: Achieving high-speed network I/O on distributed memory systems is a hard problem because their architectures are, in general, ill-suited for communication with the external world One of the problems is that messages are distributed over the private memories of the distributed memory system. This can result in poor performance since communication includes a complex scatter/gather operation. This paper presents a strategy in which the task of creating large contiguous messages is performed on the distributed-memory system, thus minimizing the overhead on the network interface. The performance results for an implementation of this strategy for an iWarp system with a HIPPI interface board are presented","Title: Automatic generation of parallel programs with dynamic load balancing\nYear: 1994\n\nAbstract: Existing parallelizing compilers are targeted towards parallel architectures where all processors are dedicated to a single application. However, a new type of parallel system has become available in the form of high perfor- mance workstations connected by high speed networks. Such systems pose new problems for compilers because the available processing power on each workstation may change with time due to other tasks competing for re- sources. We argue that it is possible for a parallelizing compiler to generate code that can dynamically shift por- tions of the application's workload between processors to improve performance. We have implemented a run-time system that supports automatically generated programs with dynamic load balancing. In this paper we describe this system and present performance measurements. We also describe the compiler functionality needed to gener- ate parallel programs with dynamic load balancing.","Title: Copy emulation in checksummed, multiple-packet communication\nYear: 1997\n\nAbstract: Data copying can be a bottleneck in end-to-end communication over high-speed networks. Emulated copy is an alternative I/O data passing scheme that preserves the API and integrity guarantees of copying but avoids the latter using virtual memory manipulations - transient output copy-on-write (TCOW), input alignment, and page swapping. We characterize and evaluate the support necessary in network adapters for emulated copy in checksummed, multiple-packet communication. Our experiments on an ATM network show that: (1) emulated copy gives performance better than that of copying even without hardware checksumming support; (2) TCOW improves multiple-packet output performance without any hardware support or changes in applications; (3) page swapping provides additional similar improvements on multiple-packet input if there is input alignment, which requires either hardware support (early-demultiplexed/system-aligned buffering) or changes in applications (pooled/application-aligned buffering); and (4) The performance of application-aligned buffering is largely unaffected by header/data splitting, a common optimization. We propose a new optimization, buffer snap-off, that extends system-aligned buffering to the general case of arbitrary, unmatched data transfer and application input buffer lengths","Title: Experimental evaluation of ATM congestion control mechanisms\nYear: 1997\n\nAbstract: A critical issue in the design of fast packet-switch-based networks is the avoidance of data loss due to congestion. In the context of ATM networks, many link-level congestion control mechanisms for ABR traffic have been proposed and simulated, and a few have been implemented. This paper presents, for the first time, an experimental comparison of several such mechanisms. To drive this comparison, we have developed a set of benchmarks that provide a quantitative characterization of congestion control performance. We also describe a simple but novel technique, the “virtual port card”, for implementing both non-native switch behavior and long link delays in ATM networks. This technique allows us to compare a wide range of mechanisms on a single flexible hardware platform. Our measurements show that while several of the ATM flow control mechanisms can eliminate cell loss, there are still several unresolved problems. First, for some traffic scenarios we see very poor application-level performance, especially in the presence of bursty traffic. Second, the performance is very sensitive to the flow control parameters and identifying an appropriate set of parameters is difficult since it depends heavily on the traffic conditions","Title: Collecting network status information for network-aware applications\nYear: 2000\n\nAbstract: Network-aware applications, i.e., applications that adapt to network con- ditions in an application specific way, need both static and d ynamic informa- tion about the network to be able to adapt intelligently to network conditions. The CMU Remos interface gives applications access to a wide range of in- formation in a network-independent fashion. Remos uses a logical topology to capture the network information that is relevant to applications in a con- cise way. However, collecting this information efficiently is challenging for several reasons: networks use diverse technologies and can be very large (Internet); applications need diverse information; and network managers might have concerns about leaking confidential information . In this paper we present an architecture for a hierarchical collector of network infor- mation. The decentralized architecture relies on data collectors that collect information on individual subnets; data collectors can collect information in manner that is appropriate for that subnet and can control the distribution of the information. For application queries that involve multiple subnets, we use a set of master collectors to partition requests and distribute subrequests to individual data collectors and to combines the results. Collectors cache recent network information to improve efficiency and respon siveness. This paper presents and justifies the collector architecture, de scribes a prototype implementation, and presents preliminary measurements characterizing its operation. Keywords—Network-aware applications, Network monitoring.","Title: Effort-limited fair (ELF) scheduling for wireless networks\nYear: 2000\n\nAbstract: While packet scheduling for wired links is a maturing area, scheduling of wireless links is less mature. A fundamental difference between wired and wireless links is that wireless media can exhibit substantial rates of link errors, resulting in significant and unpredictable loss of link capacity. This capacity loss results in a special challenge for wireless schedulers. For example, a Weighted Fair Queue (WFQ) scheduler assumes an error-free link and specifies how flows should share the link capacity. However, this specification is not sufficient to determine the correct outcome when link capacity is sharply reduced, because flows that have been allocated the same weights may differ greatly in their ability to tolerate throughput loss. In this paper, we first describe the wireless scheduling challenge in terms of an effort-outcome disconnection. Next we propose a novel notion of fair- ness for wireless links, effort-limited fairness(ELF), which extends WFQ via dynamic weight adjustments. ELF guarantees that all flows experiencing an error rate below a per-flow threshold receive their expected service, defined as a specified rate for reserved flows or a specified share of best-effort capac- ity for best-effort flows. After motivating and defining ELF, we present a practical approximation algorithm, which we evaluate through both trace- driven simulation and measurement of a prototype wireless radio network based on the WaveLAN physical layer. Keywords—Wireless networks, Quality of Service, Scheduling","Title: Wireless Emulator Demonstration\nYear: 2006\n\nAbstract: Researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we are developing a wireless emulator that enables both realistic and repeatable experimentation by leveraging physical layer emulation.","Title: A stateless architectural approach to inter-domain QoS\nYear: 2008\n\nAbstract: QoS provisioning as a generic telecom service is only useful if deployed end-to-end, so it must cover both the access segment and the interdomain segment of routes. This work focuses on the interdomain component of QoS architectures. Although the research community has been discussing several aspects of the problem, integrated architectures for true end-to-end QoS are still largely conceptual, especially if one considers mesh models and not simpler cascaded ones. Our inter-domain proposal combines offline service discovery and registration with real-time congestion notification, allowing us to significantly reduce the number of packets that were not suitably serviced, in the sense of fulfilling required Service Level Agreement constraints. We qualify our approach of dasiastatelesspsila since our proposal doesnpsilat use additional state in forwarding elements which is one of the most dramatic problems for interdomain scenarios.","Title: Topological Implications of Cascading Interdomain Bilateral Traffic Agreements\nYear: 2011\n\nAbstract: The Internet uses a model in which Autonomous Systems (AS) peer bilaterally with each other, resulting in a cascaded connectivity model: the end-to-end service that an end-user sees is the result of this cascade of bilateral traffic agreements. As a result, the routing decisions at each AS beyond the next hop are implicitly delegated, so an AS has limited control over the remaining path. While this may be considered a key feature of the Internet (e.g., helps scalability), the impact of this cascading model on the structure of the Internet is not yet well understood. In this paper, we analyze this cascaded model using concepts of game theory. Although our model cannot capture the full complexity of the real Internet - we actually aim at simplicity and try to only isolate the cascading effect -, our results suggest that cascading bilateral agreements brings order to an arbitrary graph. In particular, it brings forward some well-known properties of the Internet topology, such as the current AS hierarchy and common peering models. Finally, we compare our results with topological and routing data, obtained from CAIDA, looking for experimental evidence of our results, while further exploring the insight obtained from our model.","Title: Inter-domain service alignment using consensus\nYear: 2012\n\nAbstract: Despite its importance, end-to-end Quality-of-Service (QoS) is still an open problem mostly because of the inter-domain segment since for the access (end-user/operator) the problem has solutions for a diversity of commercially deployed architectures. The root problem lies in the coordination complexity: operators need to coordinate the traffic services they can offer, from service choice to cooperation models. We propose a framework that allows operators to agree on a useful set of services using machine-to-machine negotiation. This consensual service set dynamically balances users' demand, effort of deployment (like cost) and local business policies - ultimately obeying economics. By having the same set of services throughout the Internet, end-to-end QoS greatly reduces to an intra-domain QoS problem. We discuss the problem using a top-down approach: from formulating a multi-dimensional, iterative multi-objective optimization problem to a design proposal based on gossip protocols.","Title: DAZL: Density-Aware Zone-based packet forwarding in vehicular networks\nYear: 2012\n\nAbstract: Multi-hop message forwarding based on geographic coordinates is a fundamental building block for vehicular communication. However, the unstable links and wide range of node densities make it challenging to design an algorithm suitable for vehicular use. We introduce DAZL, a new forwarding protocol that combines three concepts in a novel way. First, multiple nodes cooperate in packet forwarding. Compared with traditional single relay schemes, this provides robustness against changes in topology and packet delivery rates. Second, network-layer slotting is used to control duplication and contention in high density scenarios. Third, a distributed prioritization algorithm is used to opportunistically maximize hop length. Through both experiments and simulations, we show that DAZL provides improvements of up to 60% in throughput over single relay forwarding, while ensuring low latency and replication.","Title: Topology reconfiguration in Wi-Fi home networks\nYear: 2013\n\nAbstract: The use of Wi-Fi is booming in home networks and it is making it harder for the technology to cope with this exponential growth. The high-bandwidth requirement of streaming services, data backups and interactive cloud applications require solutions to improve the performance of the network while simultaneously simplifying its management. This paper unveils a new Wi-Fi management paradigm relying on dynamic network topology reconfiguration that adjusts the network topology to its traffic matrix, and mitigates the performance pitfalls inherent to Wi-Fi and its fixed topology. A linear programming formulation relying on cross-layer information is provided to assess the potential gains of such solution, and an evaluation is performed that explores the achievable performance and range extension gains. The simulation results show a significant increase in the wireless network capacity - up to two fold - as well as improvements in the network range.","Title: Multi-Context TLS (mcTLS): Enabling Secure In-Network Functionality in TLS.\nYear: 2015\n\nAbstract: A significant fraction of Internet traffic is now encrypted and HTTPS will likely be the default in HTTP/2. However, Transport Layer Security (TLS), the standard protocol for encryption in the Internet, assumes that all functionality resides at the endpoints, making it impossible to use in-network services that optimize network resource usage, improve user experience, and protect clients and servers from security threats. Re-introducing in-network functionality into TLS sessions today is done through hacks, often weakening overall security. In this paper we introduce multi-context TLS (mcTLS), which extends TLS to support middleboxes. mcTLS breaks the current \\\"all-or-nothing\\\" security model by allowing endpoints and content providers to explicitly introduce middleboxes in secure end-to-end sessions while controlling which parts of the data they can read or write. We evaluate a prototype mcTLS implementation in both controlled and \\\"live\\\" experiments, showing that its benefits come at the cost of minimal overhead. More importantly, we show that mcTLS can be incrementally deployed and requires only small changes to client, server, and middlebox software.","Title: Securing Passive Replication through Verification\nYear: 2015\n\nAbstract: We show how to leverage trusted computing technology to design an efficient fully-passive replicated system tolerant to arbitrary failures. The system dramatically reduces the complexity of a fault-tolerant service, in terms of protocols, messages, data processing and non-deterministic operations. Our replication protocol enables the execution of a single protected service, replicating only its state, while allowing the backup replicas to check the correctness of the results. We implemented our protocol on Trusted Computing (TC) technology and compared it with two recent replication systems.","Title: Do You Know Where Your Headers Are? Comparing the Privacy of Network Architectures with Share Count Analysis.\nYear: 2015\n\nAbstract: Online privacy is more important now than ever. Using encryption goes a long way by hiding application data from third parties, but some amount of private information is still exposed in packet headers. Tools like Tor are designed to address this concern, and, more recently, research efforts to replace IP have begun to consider how a network architecture itself can improve privacy. Unfortunately, we do not have a good way to quantitatively compare network architectures (in terms of privacy and in general). We take the first steps in this direction by presenting share count analysis, a methodology for measuring \\\"how private\\\" an architecture is. We describe our design and implementation and present initial results indicating that this approach is promising.","Title: Bootstrapping Evolvability for Inter-Domain Routing.\nYear: 2015\n\nAbstract: It is extremely difficult to deploy newinter-domain routing protocols in today's Internet. As a result, the Internet's baseline protocol for connectivity, BGP, has remained largely unchanged, despite known significant flaws. The difficulty of deploying new protocols has also depressed opportunities for (currently commoditized) transit providers to provide value-added routing services. To help, we identify the key deployment models under which new protocols are introduced and the requirements each poses for enabling their usage goals. Based on these requirements, we argue for two modifications to BGP that will greatly improve support for new routing protocols.","Title: Enabling Vehicular Applications using Cloud Services through Adaptive Computation Offloading\nYear: 2015\n\nAbstract: There is growing interest in embedding new class of applications in vehicles to improve the user driving experience. However, the limited computational and storage resources in vehicles brings about a challenge of running computation and data intensive tasks of such applications in the vehicle's on-board unit (OBU). Moreover, embedded applications may not be easily updated by replacing hardware as upgrades in the vehicle OBUs can only happen over each vehicular life-cycle, which is of the order of 10-15 years. The advent of connectivity of vehicles to the Internet offers the possibility of offloading computation and data intensive tasks from the OBU to remote cloud servers for efficient execution. In this paper, we propose a novel architecture for bringing cloud-computing to vehicles where applications embedded in the vehicle OBU can benefit from remote execution of tasks provided as services in the cloud. We design a framework to identify and adaptively manage offloading of computation and data intensive tasks from the vehicle OBU to the cloud during application run-time. Through experimental evaluation using a preliminary prototype implementation of two computer vision applications that use our framework, we show that our approach can provide at least 3x reduction in the end-to-end application response time.","Title: Lessons Learned From A Real Vehicular Network Deployment Of Delay-Tolerant Networking\nYear: 2015\n\nAbstract: Vehicular networks are inherently unstable networks with high mobility and intermittent connectivity. These networks can greatly benefit from Delay Tolerant Networking (DTN) solutions for opportunistic connectivity in the transmission of delaytolerant data. In this paper, we evaluate the performance of different DTN routing protocols in real world vehicular networks with different degrees of connectivity in order to understand their feasibility in real vehicular environments.Our case-study application is the upload of delay-tolerant sensing data from vehicular nodes to a server on the Internet. We deploy DTN in 3 vehicular testbeds: a heterogeneous lab testbed with controlled mobility, a low-mobility high-connectivity network of harbor trucks, and a high-mobility low-connectivity city bus network. We compare 3 routing protocols: epidemic, static and PRoPHET, for which we measure delivery ratio, average delay, path length, as well as transmission and storage overhead. We analyze the results for experimental insight, and extract lessons for DTN routing protocol design.","Title: Secure Identification of Actively Executed Code on a Generic Trusted Component\nYear: 2016\n\nAbstract: Code identity is a fundamental concept for authenticated operations in Trusted Computing. In today's approach, the overhead of assigning an identity to a protected service increases linearly with the service code size. In addition, service code size continues to grow to accommodate richer services. This trend negatively impacts either the security or the efficiency of current protocols for trusted executions. We present an execution protocol that breaks the dependency between the code size of the service and the identification overhead, without affecting security, and that works on different trusted components. This is achieved by computing an identity for each of the code modules that are actually executed, and then building a robust chain of trust that links them together for efficient verification. We implemented and applied our protocol to a widely-deployed database engine, improving query-processing time up to 2× compared to the monolithic execution of the engine.","Title: Identifying the root cause of video streaming issues on mobile devices.\nYear: 2015\n\nAbstract: Video streaming on mobile devices is prone to a multitude of faults and although well established video Quality of Experience (QoE) metrics such as stall frequency are a good indicator of the problems perceived by the user, they do not provide any insights about the nature of the problem nor where it has occurred. Quantifying the correlation between the aforementioned faults and the users' experience is a challenging task due the large number of variables and the numerous points-of-failure. To address this problem, we developed a framework for diagnosing the root cause of mobile video QoE issues with the aid of machine learning. Our solution can take advantage of information collected at multiple vantage points between the video server and the mobile device to pinpoint the source of the problem. Moreover, our design works for different video types (e.g., bitrate, duration, ..) and contexts (e.g., wireless technology, encryption, ..) After training the system with a series of simulated faults in the lab, we analyzed the performance of each vantage point separately and when combined, in controlled and real world deployments. In both cases we find that the involved entities can independently detect QoE issues and that only a few vantage points are required to identify a problem's location and nature.","Title: Demystifying and mitigating TCP stalls at the server side.\nYear: 2015\n\nAbstract: TCP is an important factor affecting user-perceived performance of Internet applications. Diagnosing the causes behind TCP performance issues in the wild is essential for better understanding the current shortcomings in TCP. This paper presents a TCP flow performance analysis framework that classifies causes of TCP stalls. The framework forms the basis of a tool that is publicly available to the research community. We use our tool to analyze packet-level traces of three services (cloud storage, software download and web search) deployed by a popular Chinese service provider. We find that as many as 20% of the flows are stalled for half of their lifetime. Network-related causes, especially timeout retransmission, dominate the stalls. A breakdown of the causes for timeout retransmission stalls reveals that double retransmission and tail retransmission are among the top contributors. The importance of these causes depends however on the specific service. We also propose S-RTO, a mechanism that mitigates timeout retransmission stalls. S-RTO has been deployed on production front-end servers and results show that it is effective at improving TCP performance, especially for short flows.","Title: An Empirical Analysis of a Large-scale Mobile Cloud Storage Service.\nYear: 2016\n\nAbstract: Cloud storage services are serving a rapidly increasing number of mobile users. However, little is known about the differences between mobile and traditional cloud storage services at scale. In order to understand mobile user access behavior, we analyzed a dataset of 350 million HTTP request logs from a large-scale mobile cloud storage service. This paper presents our results and discusses the implications for system design and network performance. Our key observation is that the examined mobile cloud storage service is dominated by uploads, and the vast majority of users rarely retrieve their uploads during the one-week observation period. In other words, mobile users lean towards the usage of cloud storage for backup. This suggests that delta encoding and chunk-level deduplication found in traditional cloud storage services can be reasonably omitted in mobile scenarios. We also observed that the long idle time between chunk transmissions by Android clients should be shortened since they cause significant performance degradation due to the restart of TCP slow-start. Other observations related to session characteristics, load distribution, user behavior and engagement, and network performance.","Title: Adaptive cloud offloading for vehicular applications\nYear: 2016\n\nAbstract: The growing number of sensor-based interactive applications and services are pushing the limits of the on-board computing resources in vehicles. With vehicles increasingly being connected to the Internet, offloading the computation to cloud-computing infrastructures is an attractive solution. However, the large sensory data inputs of interactive applications makes offloading challenging across dynamic network conditions, and different application requirements or policies. To address this challenge, we design a system to adaptively offload specific vehicular application components or modules to the cloud. We particularly develop heuristic mechanisms for the placement and scheduling of modules on the On-Board Unit (OBU) and a cloud server under dynamic networking conditions during driving. Through an experimental evaluation of the end-end application response time using our prototype vehicular cloud offloading system, we show that our mechanism can help meet application response time constraints.","Title: Bootstrapping evolvability for inter-domain routing with D-BGP\nYear: 2017\n\nAbstract: The Internet's inter-domain routing infrastructure, provided today by BGP, is extremely rigid and does not facilitate the introduction of new inter-domain routing protocols. This rigidity has made it incredibly difficult to widely deploy critical fixes to BGP. It has also depressed ASes' ability to sell value-added services or replace BGP entirely with a more sophisticated protocol. Even if operators undertook the significant effort needed to fix or replace BGP, it is likely the next protocol will be just as difficult to change or evolve. To help, this paper identifies two features needed in the routing infrastructure (i.e., within any inter-domain routing protocol) to facilitate evolution to new protocols. To understand their utility, it presents D-BGP, a version of BGP that incorporates them.","Title: Secure Tera-scale Data Crunching with a Small TCB\nYear: 2017\n\nAbstract: Outsourcing services to third-party providers comes with a high security cost-to fully trust the providers. Using trusted hardware can help, but current trusted execution environments do not adequately support services that process very large scale datasets. We present LAST\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">GT</sup>\n, a system that bridges this gap by supporting the execution of self-contained services over a large state, with a small and generic trusted computing base (TCB). LAST\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">GT</sup>\n uses widely deployed trusted hardware to guarantee integrity and verifiability of the execution on a remote platform, and it securely supplies data to the service through simple techniques based on virtual memory. As a result, LAST\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">GT</sup>\n is general and applicable to many scenarios such as computational genomics and databases, as we show in our experimental evaluation based on an implementation of LAST-GT on a secure hypervisor. We also describe a possible implementation on Intel SGX.","Title: Vehicular Cloud Computing through Dynamic Computation Offloading.\nYear: 2018\n\nAbstract: The growing demand in the number of sensor–dependent applications and infotainment services in vehicles is pushing the limits of their on–board computing resources. Today, vehicles are increasingly being connected to the Internet and becoming a part of the Smart Internet–of–Things (IoT) paradigm. Leveraging such connectivity, the idea of vehicular cloud–computing, where computation for vehicular applications and services are offloaded to the cloud, becomes an attractive proposition. However, the large sensory data inputs, strict latency requirements, and dynamic wireless networking conditions make offloading of vehicular applications to the cloud very challenging. To address this challenge, we design a dynamic approach for offloading specific vehicular application components or modules. We develop heuristic mechanisms for placement and scheduling of these modules in the on–board unit versus the cloud. The highlight of the proposed design is the ability to offload computation to the cloud in an elastic manner through dynamic decisions during variable network conditions. Through an experimental evaluation using our prototype system we show the effectiveness of the design in reducing the response time for compute intensive applications across variable network conditions in two urban environments.","Title: TCP Stalls at the Server Side: Measurement and Mitigation\nYear: 2019\n\nAbstract: TCP is an important factor affecting user-perceived performance of Internet applications. Diagnosing the causes behind TCP performance issues in the wild is essential for better understanding the current shortcomings in TCP. This paper presents a TCP flow performance analysis framework that classifies causes of TCP stalls. The framework forms the basis of a tool that we use to analyze packet-level traces of three services (cloud storage, software download, and web search) deployed by a popular service provider. We find that as many as 20% of the flows are stalled for half of their lifetime. Network-related causes, especially timeout retransmissions, dominate the stalls. A breakdown of the causes for timeout retransmission stalls reveals that double retransmission and tail retransmission are among the top contributors. The importance of these causes depends however on the specific service. Based on these observations, we propose smart-retransmission time out (S-RTO), a mechanism that mitigates timeout retransmission stalls through careful and gentle aggression for retransmission. S-RTO is evaluated in a controlled network and also in a production network. The results consistently show that it is effective at improving TCP performance, especially for short flows.","Title: And Then There Were More: Secure Communication for More Than Two Parties.\nYear: 2017\n\nAbstract: Internet communication today typically involves intermediary middleboxes like caches, compression proxies, or virus scanners. Unfortunately, as encryption becomes more widespread, these middleboxes become blind and we lose their security, functionality, and performance benefits. Despite initial efforts in both industry and academia, we remain unsure how to integrate middleboxes into secure sessions---it is not even clear how to define \"secure\" in this multi-entity context.\n\nIn this paper, we first describe a design space for secure multi-entity communication protocols, highlighting tradeoffs between mutually incompatible properties. We then target real-world requirements unmet by existing protocols, like outsourcing middleboxes to untrusted infrastructure and supporting legacy clients. We propose a security definition and present Middlebox TLS (mbTLS), a protocol that provides it (in part by using Intel SGX to protect middleboxes from untrusted hardware). We show that mbTLS is deployable today and introduces little overhead, and we describe our experience building a simple mbTLS HTTP proxy.","Title: Second-Order Destination Inference using Semi-Supervised Self-Training for Entry-Only Passenger Data.\nYear: 2017\n\nAbstract: Automated data collection in urban transportation systems produces a large volume of passenger data. However, quite a few of the data are still incomplete, limiting the insight into passenger mobility. The unavailability of destination information in entry-only passenger data is a very common issue. Traditional approaches for estimating passenger destinations rely on heuristics that can recover only some of the missing destinations. To deal with the remaining incomplete data, this paper, for the first time, proposes a second-order inference methodology to leverage semi-supervised self-training to infer the missing destinations. The methodology involves the design of a base learner to predict the missing destinations based on the statistics of a selected similarity-based set, and the design of a selection strategy to select new data with high prediction confidence to update the training set. To further improve the inference, we incorporate personal history priors to modify the base learner. We evaluate our designs using two data sources: a real-data inspired traffic-passenger behavior simulation in the city of Porto, Portugal, and the real bus Automated Fare Collection (AFC) data collected from the same city. The experimental results show that compared to baseline methods that do not use self-training, our approach significantly improves the inference performance and achieves notably high accuracies.","Title: Analysis and improvement of name-based packet forwarding over flat ID network architectures\nYear: 2018\n\nAbstract: One of ICN's main challenges is attaining forwarding table scalability when confronted with a huge content space. This is specially true in flat ID architectures, which do not naturally support route aggregation for hierarchical names. Previous work has proposed improving scalability by aggregating content names in a fixed-size Bloom Filters (BF). However, the negative impact of false positive (FPs) matches on forwarding correctness and performance has not been studied thoroughly. In this paper, we study the end-to-end network performance of BF-based forwarding. We devise an analytical model that accurately models BF-based forwarding and the flow of BF-based packets over inter-domain topologies. Using this model, we show that the use of BFs for packet forwarding puts feasibility at odds with scalability. Based on our analysis, we propose and evaluate several strategies to improve the feasibility of BF-based forwarding and examine different scenarios for which BF-based forwarding is suitable.","Title: PARI: A Probabilistic Approach to AS Relationships Inference.\nYear: 2019\n\nAbstract: Over the last two decades, several algorithms have been proposed to infer the type of relationship between Autonomous Systems (ASes). While the recent works have achieved increasingly higher accuracy, there has not been a systematic study on the uncertainty of AS relationship inference. In this paper, we analyze the factors contributing to this uncertainty and introduce a new paradigm to explicitly model the uncertainty and reflect it in the inference result. We also present PARI, an exemplary algorithm implementing this paradigm, that leverages a novel technique to capture the interdependence of relationship inference across AS links.","Title: Telemetry Retrieval Inaccuracy in Programmable Switches: Analysis and Recommendations\nYear: 2021\n\nAbstract: ABSTRACTSketching algorithms or sketches are attractive as telemetry capabilities on programmable hardware switches since they offer rigorous accuracy guarantees and use compact data structures. However, we find that in practice, their actual implementations can have a significant (up to 94×) accuracy drop compared to theoretical expectations. We find that the delays incurred by pulling and resetting the data plane state induce accuracy degradation. We design and implement solutions to reduce the delays and show that our solutions can help eliminate almost all the inaccuracy of existing sketch workflows.","Title: Meeting connected vehicle application requirements: it's not just about bandwidth\nYear: 2021\n\nAbstract: BSTRACTThe growing popularity of connected vehicles is driving the development of a new class of latency-sensitive applications. The applications can benefit from edge clouds but they need timely responses to their requests. For applications based on video and other sensor data, this necessitates high burst throughput from the network, which results in a challenging scheduling problem since applications have diverse request sizes, rates, and deadlines. While the problem of managing latency sensitive bursty traffic has been considered in data centers, wireless networks use variable bit rates, which further exacerbates the problem. In this paper, we first use simple examples to show that traditional network fairness and quality-of-service (QoS) solutions are not appropriate for latency sensitive applications using cloud services at the wireless edge. We then sketch a possible solution that addresses the challenges of combining Service Level Agreements that focus on burst transfers with a network scheduler that is resource-aware. Finally, we use a simplified network, namely Wi-Fi based emulation, to show how our approach enables both the network administrator and applications to meet their goals.","Title: Time-division TCP for reconfigurable data center networks\nYear: 2022\n\nAbstract: Recent proposals for reconfigurable data center networks have shown that providing multiple time-varying paths can improve network capacity and lower physical latency. However, existing TCP variants are ill-suited to utilize available capacity because their congestion control cannot react quickly enough to drastic variations in bandwidth and latency. We present Time-division TCP (TDTCP), a new TCP variant designed for reconfigurable data center networks. TDTCP recognizes that communication in these fabrics happens over a set of paths, each having its own physical characteristics and cross traffic. TDTCP multiplexes each connection across multiple independent congestion states---one for each distinct path---while managing connection-wide tasks in a shared fashion. It leverages network support to receive timely notification of path changes and promptly matches its local view to the current path. We implement TDTCP in the Linux kernel. Results on an emulated network show that TDTCP improves throughput over both traditional TCP variants, such as DCTCP and CUBIC, and multipath TCP by 24--41% without requiring significant in-network buffering to hide path variations.","Title: Time-Sensitive Cooperative Perception for Real-Time Data Sharing over Vehicular Communications: Overview, Challenges, and Future Directions\nYear: 2022\n\nAbstract: Cooperative perception is a prospective application to improve road safety by having connected autonomous vehicles (CAVs) exchange their raw or processed sensor data over vehicular communications. Since CAVs heavily rely on sensor-based perception, including vision cameras, LiDARs, and radars, cooperative perception has an immense potential to improve road safety. At the same time, a variety of sensors and edge servers have been widely deployed in smart cities, and such sensors and servers might be able to empower CAVs on public roads. In this article, we comprehensively study such cooperative perception for overview, technical challenges, practical requirements, prospective system designs, current approaches, and future research directions. In particular, we focus on the time sensitivity of the cooperative perception frameworks, in which delays of computing and communications lead to detection errors. In addition, we comprehensively study sensor fusion frameworks and models to improve the detection accuracy and reliability of CAVs while avoiding information flooding and/or rumor spreading. Since network congestion might lead to packet collisions and/or delays, congestion control might be essential to use cooperative perception in practice. Finally, we discuss the technical and ethical challenges of using cooperative perception on public roads and conclude with future research directions."],"string":"[\n \"Title: Parallelizing a New Class of Large Applications over High-speed Networks\\nYear: 1991\\n\\nAbstract: parallel architecture. In both cases, the efforts require Several large applications have been parallelized that the persons responsible for the porting are on Nectar, a network-based multicomputer recently intimately familiar with the applications. Since large developed by Carnegie Mellon. These applications applications tend to involve substantial application- were previously either too large or too complex to be specific knowledge, this implies that often only easily implemented on distributed memory parallel application scientists themselves can do the porting. systems. Parallelizing these applications was made possible by the cooperative use of many existing This definitely is not the best way of using their time, general-purpose computers over high-speed and as a result, many large applications have never been networks, and by an implementation methodology implemented on parallel machines. based on a clean separation between application- specific and system-specific code. We illustrate What we need are parallel architectures and these points using our experience with parallelizing programming tools to provide direct and general three real-world applications. The success in these support for parallelizing large applications. These tools applications clearly points out a new direction in parallel processing. should be at a higher level than send and receive primitives, or synchronization or shared data primitives. The objective is to be able to port large applications\",\n \"Title: Customizable virtual private network service with QoS\\nYear: 2001\\n\\nAbstract: In this paper, we propose and implement Virtual NetworkService #VNS#, a value-added network servicefor deploying virtual private networks #VPN# in amanaged wide area IP network. The key feature ofVNS is its capability of providing a customer with aVPN that is customizable with management capabilitiesand performance properties comparable to a dedicatedphysical network. In addition, VNS ensurescon#dentiality of data and principals through the useof IPSEC. The main technique underlying...\",\n \"Title: Building Self-Configuring Services Using Service-Specific Knowledge\\nYear: 2004\\n\\nAbstract: A self-configuring service can automatically leverage distributed service components and resources to compose an optimal configuration according to both the requirements of a particular user and the system characteristics. One major challenge for building such services is how to bring in service-specific knowledge, e.g., what components are needed and optimization criteria to use, while still allowing reuse of common service composition functionalities. In this paper, we present an architecture in which service developers express their service-specific knowledge in the form of a service recipe that is used by a generic synthesizer to perform service composition automatically. We apply our approach to three different services to illustrate the flexibility and simplicity of the recipe representation. We use simulations based on Internet measurements to evaluate how an appropriate optimization algorithm can be selected according to a developer's service-specific trade-off between optimality and cost of optimization.\",\n \"Title: Low-overhead channel-aware rate adaptation\\nYear: 2007\\n\\nAbstract: Current rate selection algorithms are dominated by probe-based approaches that search for the best transmission rate using trial-and-error. When operating over a dynamic channel, probe-based techniques can perform poorly since they inefficiently search for the moving target presented by the constantly changing channel. We have developed a channel-aware rate adaptation algorithm - CHARM - that responds quickly to dynamic channel changes, and significantly outperforms probe-based algorithms in many instances. Unlike previous approaches, CHARM leverages channel reciprocity to obtain channel information without incurring RTS/CTS overhead. Our work shows that channel-aware rate selection is viable, and can significantly outperform probe-based rate adaptation over both static and dynamic channels.\",\n \"Title: Understanding tradeoffs in incremental deployment of new network architectures\\nYear: 2013\\n\\nAbstract: Despite the plethora of incremental deployment mechanisms proposed, rapid adoption of new network-layer protocols and architectures remains difficult as reflected by the widespread lack of IPv6 traffic on the Internet. We show that all deployment mechanisms must address four key questions: How to select an egress from the source network, how to select an ingress into the destination network, how to reach that egress, and how to reach that ingress. By creating a design space that maps all existing mechanisms by how they answer these questions, we identify the lack of existing mechanisms in part of this design space and propose two novel approaches: the \\\"4ID\\\" and the \\\"Smart 4ID\\\". The 4ID mechanism utilizes new data plane technology to flexibly decide when to encapsulate packets at forwarding time. The Smart 4ID mechanism additionally adopts an SDN-style control plane to intelligently pick ingress/egress pairs based on a wider view of the local network. We implement these mechanisms along with two widely used IPv6 deployment mechanisms and conduct wide-area deployment experiments over PlanetLab. We conclude that Smart 4ID provide better overall performance and failure semantics, and that innovations in the data plane and control plane enable straightforward incremental deployment.\",\n \"Title: Discovery and Composition of Per-Domain Behaviours - a Service Abstraction Approach.\\nYear: 2010\\n\\nAbstract: We discuss the problem of composing Quality-of-Service across several administrative domains considering an evolved DiffServ notion of Per-Domain Behavior (PDB). We discuss two components of the problem: path discovery and the effect of composing PDBs. We assume the most general scenario: domains are free to adopt any PDB, as long there are common semantics and a set of well-known QoS parameters (e. g. one-way delay, peak/sustained bandwidth, etc.). Thus we adopt an abstract representation of PDBs.We obtain three main results. First, we show that a distributed path discovery scheme is feasible and more scalable than a centralized one. Second, we show the outcome of inter-domain QoS composition, for general metrics and for Internet-alike topologies. Finally, and as an important practical result, we show that the Internet may not need a centralized governance model, in terms of the definition of inter-domain PDBs.\",\n \"Title: Exploiting Information Relationships for Access Control\\nYear: 2005\\n\\nAbstract: Pervasive computing environments offer a multitude of information services that provide potentially complex types of information. Therefore, when running access control for sensitive information, these environments need to take relationships between information into account. Other approaches to relationship-aware access control (e.g., based on Semantic Web rule engines) are often expensive and based on a centralized design. In this paper, we identify three types of information relationships (bundling-based, combination-based, and granularity-based) that are common and important in pervasive computing, and we integrate support for them in a distributed, certificate-based access control architecture. In our approach, access control is fully distributed while sophisticated rule engines can still be used to deal with more complex access control cases. To demonstrate the feasibility of our design, we give a complexity analysis of the architecture and a performance analysis of a prototype implementation.\",\n \"Title: Supporting Dynamic Inter-Class Resource Sharing: A Multi-Class Qos Routing Algorithm\\nYear: 1999\\n\\nAbstract: In an integrated services network, resources are shared by multiple traffic classes. Service classes that deliver Quality-of-Service (QoS) to applications have priority over others that do not. In such a multi-service network, routing decisions for high priority QoS traffic will affect what resources are available for lower priority traffic: Poor route selection can result in congestion for, or even starvation of, lower priority traffic. Whereas many studies have focused on routing algorithms that optimize the network throughput for individual service classes, little effort has been devoted to routing algorithms that address inter-class resource sharing. In this paper, we propose a routing algorithm that allows dynamic sharing of link resources among multiple traffic classes. The algorithm is based on the concept of \\\"virtual residual bandwidth,\\\" which is derived from the link residual bandwidth by taking the congestion condition of low priority traffic into account. By using the virtual residual bandwidth in the link cost function for QoS sessions, we discourages QoS sessions from using links that are heavily loaded with low priority traffic. Our approach is simple in the sense that besides changing the link cost function, no other changes to the routing algorithms for individual service classes are required. An extensive simulation study shows that when the traffic load is unevenly distributed, significant performance improvements can be achieved for low priority traffic without sacrificing performance for high priority traffic. The result demonstrates that QoS routing is important even when the QoS traffic load is light and call blocking is not an issue.\",\n \"Title: Supporting dynamic inter-domain network composition: domain discovery\\nYear: 2009\\n\\nAbstract: When two administratively independent domains need to engage in cooperation of some kind, some initial common known point of contact must exist, both in terms of the application topological position (i.e., IP address, transport protocol and port) and in terms of the interface technology (e.g., the protocol suite of the interaction). In a world of many domains of many types (not necessarily Autonomous Systems in the sense of interdomain routing), manual or single-directory-based operations are not practical (or even feasible); hence, some form of autonomic discovery and handshaking of domains is needed. We propose and evaluate several strategies to allow autonomic bootstrapping of inter-domain operations, all fit to be deployed as BGP extensions. We show the time/message overhead tradeoff: it's possible to obtain the absolute minimum message complexity of O(N) but at the cost of central administrative burden or, for fully distributed schemes, a tradeoff (message/time complexity) of O(N2)/O(N) or O(N2)/O(log2N).\",\n \"Title: Design, Implementation, and Evaluation of the Remos Network Monitoring System\\nYear: 2003\\n\\nAbstract: Remos provides resource information to distributed applications. Its design goals of scalability, flexibility, and portability are achieved through an architecture that allows components to be positioned across the network, each collecting information about its local network. To collect information from different types of networks, Remos provides several Collectors that use different technologies, including SNMP and benchmarking. By matching the Collector to the particular network environment and by providing an architecture for distributing the output of these collectors across all querying environments, Remos collects appropriately detailed information at each site and distributes this information where needed in a scalable manner. Remos has been implemented and tested in a variety of networks and is in use in a number of different environments.\",\n \"Title: A statistical channel model for realistic simulation in VANET.\\nYear: 2012\\n\\nAbstract: Vehicular Ad-hoc NETwork (VANET) simulation is crucial for the development of new protocols and applications. Even though real-world experimentation is the de facto benchmarking solution for any of these, the first evaluations must be made through simulation, due to the ease of changing parameters and scenarios.In this work, we propose a statistical channel model for VANET simulation based on the observation of data from real-world experiments, obtained from an IEEE 802.11p/WAVE compliant testbed. We statistically characterize fading in VANET communication and propose a combination of models for Line-of-Sight (LoS) transmission.Simulations using the proposed model were compared with real-world experiment results and, furthermore, the model was validated against a set of measurements from an independent research group, fitting it with a high concordance level, thus proving to be effective and general.\",\n \"Title: Network-Sensitive Service Discovery\\nYear: 2003\\n\\nAbstract: We consider the problem of network-sensitive service selection (NSSS): finding services that match a partic- ular set of functional and network properties. Cur- rent solutions handle this problem using a two-step pro- cess. First, a user obtains a list of candidates through service discovery. Then, the user applies a network- sensitive server selection technique to find the best ser- vice. Such approaches are complex and expensive since each user has to solve the NSSS problem inde- pendently. In this paper, we present a simple alterna- tive: network-sensitive service discovery (NSSD). By in- tegrating network-sensitivity into the service discovery process, NSSD allows users who are looking for services to specify both the desired functional and network prop- erties at the same time. Users benefit since they only have to solve a restricted version of the server selection problem. Moreover, NSSD can solve the NSSS problem more efficiently by amortizing the overhead over many users. We present the design of NSSD, a prototype im- plementation, and experimental results that illustrate how NSSD can be utilized for different applications.\",\n \"Title: DIRC: increasing indoor wireless capacity using directional antennas\\nYear: 2009\\n\\nAbstract: The demand for wireless bandwidth in indoor environments such as homes and offices continues to increase rapidly. Although wireless technologies such as MIMO can reach link throughputs of 100s of Mbps (802.11n) for a single link, the question of how we can deliver high throughput to a large number of densely-packed devices remains an open problem. Directional antennas have been shown to be an effective way to increase spatial reuse, but past work has focused largely on outdoor environments where the interactions between wireless links can usually be ignored. This assumption is not acceptable in dense indoor wireless networks since indoor deployments need to deal with rich scattering and multipath effects. In this paper we introduce DIRC, a wireless network design whose access points use phased array antennas to achieve high throughput in dense, indoor environments. The core of DIRC is an algorithm that increases spatial reuse and maximizes overall network capacity by optimizing the orientations of a network of directional antennas. We implemented DIRC and evaluated it on a nine node network in an enterprise setting. Our results show that DIRC improves overall network capacity in indoor environments, while being flexible enough to adapt to node mobility and changing traffic workloads.\",\n \"Title: Aroma: Language Support for Distributed Objects\\nYear: 1992\\n\\nAbstract: Aroma simplifies the task of parallelizing large applications in multicomputers by providing applications with a shared object space. Aroma supports both traditional monolithic objects and aggregate objects that can be partitioned across multiple nodes. Aggregate objects support data parallelism efficiently. An Aroma program consists of tasks that operate on shared objects. Tasks typically execute on the node on which their input data is located, thus minimizing communication. Shared data objects have synchronization properties associated with them, making it possible to parallelize a large class of applications without using explicit, locks and condition variables. The authors present and justify the Aroma language features, and give examples of Aroma programs. Aroma has been implemented on the Nectar multicomputer. The authors give performance results for several applications.\",\n \"Title: Analyzing communication latency using the Nectar communication processor\\nYear: 1992\\n\\nAbstract: For multicomputer applications, the most important performance parameters of a network is the latency for short messages. In this paper we present an analysis of communication latency using measurement of the Nectar system. Nectar is a high-performance multicomputer built around a high-bandwidth crosspoint network. Nodes are connected to the Nectar network using network coprocessors that are primarily responsible the protocol processing, but that can also execute application code. This architecture allows us to analyze message latency both between workstations with an outboard protocol engine and between lightweight nodes with a minimal runtime system and a fast, simple network interface (the coprocessors). We study how much context switching, buffer management and protocol processing contribute to the communication latency and we discuss how the latency is influenced by the protocol implementation.\",\n \"Title: Distributed Load-Sensitive Routing For Computationally-Constrained Flows\\nYear: 2003\\n\\nAbstract: A network that provides not only connectivity but also computational resources to application flows will enable a new array of network services. For example, applications that require content adaptation can be deployed more easily in a network that provides integrated communication and computational resources. In this paper, we study the problem of finding a path for a flow that has both computational and bandwidth constraints. We present a distributed load-sensitive routing algorithm that generates precomputed routing information and optimizes the routing decisions for both applications and computational and communication resource providers. We show through simulations that our distributed approach performs comparably to a centralized algorithm and is more resilient to longer routing update intervals.\",\n \"Title: Project Aura: Toward Distraction-Free Pervasive Computing\\nYear: 2002\\n\\nAbstract: Today's systems distract users in many ways, thereby reducing their effectiveness. Aura aims to minimize user distractions by trading plentiful computing resources for this scarcest of resources. Aura's approach is based on two broad concepts. First, it uses proactivity, so a system layer can anticipate requests from a higher layer. Second, it is self-tuning, so layers can adapt by observing current demands and adjusting their performance and resource usage characteristics accordingly. By applying these concepts at every layer in the system, the authors hope to build an environment that adapts to the user's context and needs with minimal user involvement. They will deploy a large-scale Aura system at Carnegie Mellon to help evaluate the research in a realistic setting.\",\n \"Title: Customizable Cooperative Metering for Multi-ingress Service Level Agreements in Differentiated Network Services\\nYear: 2001\\n\\nAbstract: In the Differentiated Service architecture an interesting class of SLAs provides guarantees for the traffic flowing from multiple ingress nodes into a single or group of egress nodes. For many distributed services, like a VPN service, where multiple ingress points are sending to the same egress, customers would like to control the bandwidth distribution across the ingress routers, based on their specific requirements. In this paper we present a simple strategy called CCDM (Customized Coordinated Dynamic Metering) that supports a customizable distribution of bandwidth across ingress routers. The bandwidth distribution policy is specified by customers in the form of router extensions (code modules) that execute in the control plane of the ingress routers. We describe and motivate the CCDM design. We also describe an implementation of CCDM in the context of the Darwin system and present measurement results for three different customized policies, demonstrating the customizability aspect of our solution.\",\n \"Title: Virtual traffic lights in partial deployment scenarios.\\nYear: 2013\\n\\nAbstract: Vehicular ad hoc networks (VANETs) are seen as an important enabling technology for improving both traffic safety and efficiency. Virtual Traffic Lights (VTLs) are a promising proposal for reducing travel time by efficiently controlling road intersections. VTLs use vehicle-to-vehicle communication to dynamically optimize traffic flow and they display traffic light information on the windshield. However, research so far has assumed that all vehicles are equipped with VTL support and it has ignored the incremental deployment phase, which could last decades. In this paper we present a solution for a VTL partial deployment scenario that is based on the idea of having VTL equipped cars display traffic light information on the outside of the vehicle. This allows drivers in non-equipped vehicles, or even pedestrians, to see the light color and respond accordingly. We show that the benefits of VTLs in terms of intersection throughput and average delay reduction grow as a function of the penetration rate of equipped vehicles.\",\n \"Title: Network-Aware Distributed Computing: A Case Study\\nYear: 1998\\n\\nAbstract: The development of network-aware applications, i.e. applications that dynamically adapt to network conditions, has had some success in the domain of multimedia applications, but progress has been very slow for distributed computing applications. The reason is that the relationship between application performance and network performance is typically more complex for that class of applications, making adaptation difficult. In this paper are introduce two adaptation methods for distributed computing applications, one based on a performance model and another based on balancing computation and communication time. We illustrate the two methods using a simple distributed application (matrix multiply) and compare their performance. We show that both methods can correctly estimate the best number of nodes to use on our testbed. We also show that both methods have weaknesses. Model-based adaptation requires an accurate performance model and is sensitive to errors in measurements of the system parameters. The ratio-based method is more robust but less general.\",\n \"Title: User-Level Protocol Servers with Kernel-Level Performance\\nYear: 1998\\n\\nAbstract: Compared to kernel-level servers, user-level ones can be debugged and maintained more easily and safely, but traditionally have had much worse performance. We de- scribe a novel Z/O-oriented IPC facility that combines the em- ulated copy data passing scheme for monolithic systems with new copy avoidance techniques for microkernel systems. Un- like previous optimizations, I/O-oriented IPC does not re- quire changes in existing user applications or complex re- structuring of servers; it offers an API with copy semantics and allows the same servers to be installed at kernel or user level. In end-to-end experiments on an ATM network at 512 Mbps, I/O-oriented IPC gave user-level protocol servers performance approaching that of kernel-level ones. Perfor- mance differences scaled roughly inversely to the processor% SPECint95 rating, projecting fast further improvement.\",\n \"Title: Using physical layer emulation to optimize and evaluate mobile and wireless systems\\nYear: 2008\\n\\nAbstract: Testing and evaluating protocols and applications for wireless networks and mobile users is challenging because the physical environment has a significant impact on the behavior and dynamics of the system. It is however important that these physical world effects are considered during system implementation and evaluation to ensure correct and efficient operation. Unfortunately, since these physical world effects are hard to control and model, this adds considerable complexity to system development. In this paper we show how a wireless networking testbed based on signal propagation emulation was used in the development, testing, and evaluation of mobile systems. The paper is organized as two case studies at different levels of the system: roaming in 802.11 networks and video streaming. We found that the combination of realism and control improved both efficiency and performance during development.\",\n \"Title: Network Anomaly Detection Using Co-clustering.\\nYear: 2012\\n\\nAbstract: Early Internet architecture design goals did not put security as a high priority. However, today Internet security is a quickly growing concern. The prevalence of Internet attacks has increased significantly, but still the challenge of detecting such attacks generally falls on the end hosts and service providers, requiring system administrators to detect and block attacks on their own. In particular, as social networks have become central hubs of information and communication, they are increasingly the target of attention and attacks. This creates a challenge of carefully distinguishing malicious connections from normal ones. Previous work has shown that for a variety of Internet attacks, there is a small subset of connection measurements that are good indicators of whether a connection is part of an attack or not. In this paper we look at the effectiveness of using two different co-clustering algorithms to both cluster connections as well as mark which connection measurements are strong indicators of what makes any given cluster anomalous relative to the total data set. We run experiments with these co-clustering algorithms on the KDD 1999 Cup data set. In our experiments we find that soft co-clustering, running on samples of data, finds consistent parameters that are strong indicators of anomalous detections and creates clusters, that are highly pure. When running hard co-clustering on the full data set (over 100 runs), we on average have one cluster with 92.44% attack connections and the other with 75.84% normal connections. These results are on par with the KDD 1999 Cup winning entry, showing that co-clustering is a strong, unsupervised method for separating normal connections from anomalous ones. Finally, we believe that the ideas presented in this work may inspire research for anomaly detection in social networks, such as identifying spammers and fraudsters.\",\n \"Title: Using Architectural Style as a Basis for System Self-repair\\nYear: 2002\\n\\nAbstract: An increasingly important requirement for software systems is the capability to adapt at run time in order to accommodate varying resources, system errors, and changing requirements. For such self-repairing systems, one of the hard problems is determining when a change is needed, and knowing what kind of adaptation is required. Recently several researchers have explored the possibil- ity of using architectural models as a basis for run time monitoring, error de- tection, and repair. Each of these efforts, however, has demonstrated the feasi- bility of using architectural models in the context of a specific style. In this paper we show how to generalize these solutions by making architectural style a parameter in the monitoring/repair framework and its supporting infrastruc- ture. The value of this generalization is that it allows one to tailor monitor- ing/repair mechanisms to match both the properties of interest (such as per- formance or security), and the available operators for run time adaptation.\",\n \"Title: A conference gateway supporting interoperability between SIP and H.323\\nYear: 2001\\n\\nAbstract: Increased network bandwidth is making desktop video conferencing an attractive application for an increasing number of computer users. Unfortunately, two competing standards for video conferencing signaling are in use, H.323 and SIP. In this paper we look at the interoperability between these two standards by developing a conferencing gateway that supports conferences involving both SIP and H.323 clients. By appropriately translating between H.323 and SIP operations, our prototype gateway supports basic multi-party video conferencing between NetMeeting (an H.323 client) and VIC (a SIP client) without modifications to the clients. However, our experiments also show that seamless interoperation would require changes to the client implementations and the standards.\",\n \"Title: Software Architecture-Based Adaptation for Pervasive Systems\\nYear: 2002\\n\\nAbstract: An important requirement for pervasive computing systems is the ability to adapt at runtime to handle varying resources, user mobility, changing user needs, and system faults. In this paper we describe an approach in which dynamic adaptation is supported by the use of software architectural models to monitor an application and guide dynamic changes to it. The use of externalized models permits one to make reconfiguration decisions based on a global perspective of the running system, apply analytic models to determine correct repair strategies, and gauge the effectiveness of repair through continuous system monitoring. We illustrate the application of this idea to pervasive computing systems, focusing on the need to adapt based on performance-related criteria and models.\",\n \"Title: Software architecture-based adaptation for Grid computing\\nYear: 2002\\n\\nAbstract: Grid applications must increasingly self-adapt dynamically to changing environments. In most cases, adaptation has been implemented in an ad hoc fashion, on a per-application basis. This paper describes work which generalizes adaptation so that it can be used across applications by providing an adaptation framework. This framework uses a software architectural model of the system to analyze whether the application requires adaptation, and allows repairs to be written in the context of the architectural model and propagated to the running system. In this paper, we exemplify our framework by applying it to the domain of load-balancing a client-server system. We report on an experiment conducted using our framework, which illustrates that this approach maintains architectural requirements.\",\n \"Title: Software support for outboard buffering and checksumming\\nYear: 1995\\n\\nAbstract: Data copying and checksumming are the most expensive operations when doing high-bandwidth network IO over a high-speed network. Under some conditions, outboard buffering and checksumming can eliminate accesses to the data, thus making communication less expensive and faster. One of the scenarios in which outboard buffering pays off is the common case of applications accessing the network using the Berkeley sockets interface and the Internet protocol stack. In this paper we describe the changes that were made to a BSD protocol stack to make use of a network adaptor that supports outboard buffering and checksumming. Our goal is not only to achieve \\\"single copy\\\" communication for application that use sockets, but to also have efficient communication for in-kernel applications and for applications using other networks. Performance measurements show that for large reads and writes the single-copy path through the stack is significantly more efficient than the original implementation.\",\n \"Title: Access control to people location information\\nYear: 2005\\n\\nAbstract: Ubiquitous computing uses a variety of information for which access needs to be controlled. For instance, a person's current location is a sensitive piece of information that only authorized entities should be able to learn. Several challenges arise in the specification and implementation of policies controlling access to location information. For example, there can be multiple sources of location information. The sources can be within different administrative domains, which might allow different entities to specify policies, and policies need to be flexible. We address these issues in our design of a distributed access control mechanism for a people location system. Our design encodes policies as digital certificates, which enables decentralized storage of policies. We also present an algorithm for the discovery of distributed certificates. Furthermore, we discuss several privacy issues and show how our design addresses them. To show feasibility of our design, we built an example implementation based on SPKI/SDSI certificates. Using measurements, we quantify the influence of access control on query processing time. We also discuss trade-offs between RSA-based and DSA-based signature schemes for digital certificates.\",\n \"Title: Network-Aware Parallel Computing with Remos\\nYear: 1998\\n\\nAbstract: Networked systems provide a cost-effective platform for parallel computing, but the applications have to deal with the changing availability of computation and communication resources. Network-awareness is a recent attempt to bridge the gap between the realities of networks and the demands of applications. Network-aware applications obtain information about their execution environment and dynamically adapt to enhance their performance. Adaptation is especially important for synchronous parallel applications since a single busy communication link can become the bottleneck and degrade overall performance dramatically. This paper presents Remos, a uniform API that allows applications to obtain relevant network information, and reports on the development of parallel applications in this environment. The challenges in defining a uniform interface include network heterogeneity, diversity and variability in network traffic, and resource sharing in the network and even inside an application. The first implementation of the Remos system is hosted on an IP-based network testbed. The paper reports on our methodology for developing adaptive parallel applications for high-speed networks with Remos, and presents results that highlight the importance and effectiveness of adaptive parallel computing.\",\n \"Title: Adaptive Distributed Applications on Heterogeneous Networks\\nYear: 1999\\n\\nAbstract: Distributed applications execute in environments that can include different network architectures as well as a range of compute platforms. Furthermore, these resources are shared by many users. Therefore these applications receive varying levels of service from the environment. Since the availability of resources in a networked environment often determines overall application performance, adaptivity is necessary for efficient execution and predictable response time. However, heterogeneous systems pose many challenges for adaptive applications. We discuss the range of situations that can benefit from adaptivity in the context of a set of system and environment parameters. Adaptive applications require information about the status of the execution environment and heterogeneous environments call for a portable system to provide such information. We discuss Remos (Resource Monitoring System), a system that allows applications to collect information about network and host conditions across different network architectures. Finally, we report our experience and performance results from a set of adaptive versions of Airshed pollution modeling application executing on a networking testbed.\",\n \"Title: A bandwidth advisor for wireless networks\\nYear: 2002\\n\\nAbstract: Many network intensive applications can benefit substantially from reasonable estimates of future available bandwidth. As a simple example, consider a user, John, that is about to board a flight that is leaving shortly. Using his palmtop equipped with the Aura ubiquitous computing system, John has just finished editing some very large documents that he needs to email over the airport's wireless network. Just before he begins transmission, a 747 begins deplaning passengers at a gate adjacent to where John is waiting; these deplaning passengers are heavily loading the network in John's cell. John's Aura client contacts the bandwidth advisor and learns that there is insufficient bandwidth for John to complete his transmission before his plane leaves. Fortunately, Aura learns from the bandwidth advisor that a nearby cell has ample bandwidth which enables John to move into that cell briefly and complete his transmission before catching his plane.The utility of bandwidth advisors has lead to efforts such as Remos and the Network Weather Service which have investigated providing bandwidth advice in wired network settings. This research builds on this previous work by developing a bandwidth advisor that is specifically tuned for wireless networks, and is suited to the needs of mobile applications.\",\n \"Title: A simple mechanism for capturing and replaying wireless channels\\nYear: 2005\\n\\nAbstract: Physical layer wireless network emulation has the potential to be a powerful experimental tool. An important challenge in physical emulation, and traditional simulation, is to accurately model the wireless channel. In this paper we examine the possibility of using on-card signal strength measurements to capture wireless channel traces. A key advantage of this approach is the simplicity and ubiquity with which these measurements can be obtained since virtually all wireless devices provide the required metrics. We show that for low delay spread environments wireless traces gathered using this method can be replayed in a physical wireless emulator to produce higher layer network behavior that is similar to the behavior that would have occurred in the real world. Thus, wireless channel traces gathered using on-card metrics are an effective means of enabling existing low delay spread wireless testbeds to be emulated.\",\n \"Title: Implementing access control to people location information\\nYear: 2004\\n\\nAbstract: Ubiquitous computing uses a variety of information for which access needs to be controlled. For instance, a person's current location is asensitive piece of information, which only authorized entities should be able to learn. Several challenges arise in the specification and implementation of policies controlling access to location information. For example, there can be multiple sources of location information, the sources can be within different administrative domains, different administrative domains might allow different entities to specify policies, and policies need to be flexible. Weaddress these issues in our design of an access control mechanism for a people location system. Our design encodes policies as digital certificates. We present an example implementation based on SPKI/SDSI certificates. Using measurements, we quantify the influence of access control on query processing time. We also discuss trade-offs between RSA-based and DSA-based signature schemes for digital certificates.\",\n \"Title: Design, implementation and evaluation of an efficient opportunistic retransmission protocol\\nYear: 2009\\n\\nAbstract: This paper presents an efficient opportunistic retransmission protocol (PRO, Protocol for Retransmitting Opportunistically) to improve the performance of IEEE 802.11 WLANs. PRO is a link-layer protocol that allows overhearing nodes to function as relays that retransmit on behalf of the source after they learn about a failed transmission. Relays with stronger connectivity to the destination have a higher chance of delivering the packet than the source does, thereby resulting in a more efficient use of the channel. PRO has four main features. First, channel reciprocity coupled with a run-time calibration process is used to estimate the instantaneous link quality to the destination. Second, a local qualification process filters out poor relays early. Third, a distributed relay selection algorithm chooses the best set of eligible relays among all qualified relays and prioritizes them. Finally, 802.11e Enhanced Distributed Channel Access (EDCA) is leveraged to make sure high priority relays transmit with high probability. PRO is designed to coexist with legacy 802.11 stations. We have implemented PRO in the driver of a commodity wireless card. Our extensive evaluation on both a controlled testbed and in the real world shows that PRO boosts throughput in diverse wireless environments, and especially in when there is significant contention for the channels, under fading, and with user mobility.\",\n \"Title: Design, implementation, and evaluation of a single-copy protocol stack\\nYear: 1998\\n\\nAbstract: Data copying and checksumming are the most expensive operations on hosts performing high-bandwidth network I/O over a high-speed network, Under some conditions, outboard buffering and checksumming can eliminate accesses to the data, thus making communication less expensive and faster. One of the scenarios in which outboard buffering and checksumming pays off is the common case of applications accessing the network using the Berkeley sockets interface and the Internet protocol stack. In this paper, we describe the host software for a host interface with outboard buffering and checksumming support. The platform used is DEC Alpha workstations with a Turbochannel I/O bus and running the DEC OSF/1 operating system. Our implementation does not only achieve 'single copy' communication for applications that use sockets, but it also interoperates efficiently with in-kernel applications and other network devices. Measurements show that for large reads and writes the single-copy path through the stack is five to seven times more efficient than the traditional implementation. We also present a detailed analysis of the measurements using a simple I/O model. (C) 1998 John Wiley & Sons, Ltd.\",\n \"Title: Exploiting information relationships for access control in pervasive computing\\nYear: 2006\\n\\nAbstract: Many information services in pervasive computing offer rich information, which is information that includes other types of information. For example, the information listed in a person’s calendar entry can reveal information about the person’s location or activity. To avoid rich information from leaking its included information, we must consider the semantics of the rich information when controlling access to this information. Other approaches that reason about the semantics of information (e.g., based on Semantic Web rule engines) are based on a centralized design, whose drawback is a single point of failure. In this paper, we exploit information relationships for capturing the semantics of information. We identify three types of information relationships that are common and important in pervasive computing and integrate support for them in a distributed, certificate-based access control architecture. In the architecture, individuals can either define their own information relationships or refer to relationships defined by a standardization organization. In our approach, access control is fully distributed while sophisticated rule engines can still be used to deal with more complex access control cases. To demonstrate the feasibility of our design, we give a complexity analysis of the architecture and a performance analysis of a prototype implementation.\",\n \"Title: CHARQ: Cooperative Hybrid ARQ for wireless video streaming\\nYear: 2009\\n\\nAbstract: Forward error correction (FEC) coding and automatic repeat request (ARQ) are two commonly used techniques to tackle packet erasures in wireless video streaming. To preserve flexibility while reducing end-to-end latency, hybrid ARQ (HARQ) has been proposed as an alternative that combines the advantages of FEC and ARQ. This paper presents cooperative hybrid ARQ (CHARQ) that can further boost wireless video streaming quality. CHARQ takes advantage of the fact that, in the wireless environment, broadcast is free (from the sender's point of view) and that errors are location dependent so an intermediate proxy that overhears the source's transmission may transmit on behalf of the source to increase throughput efficiency. Simulation results show improved performance with the aid of cooperative proxies.\",\n \"Title: Efficient channel-aware rate adaptation in dynamic environments\\nYear: 2008\\n\\nAbstract: Increasingly, 802.11 devices are being used by mobile users. This results in very dynamic wireless channels that are difficult to use efficiently. Current rate selection algorithms are dominated by probe-based approaches that search for the best transmission rate using trial-and-error. In mobile environments, probe-based techniques often perform poorly because they inefficiently search for the moving target presented by the constantly changing channel. We have developed a channel-aware rate adaptation algorithm CHARM - that uses signal strength measurements collected by the wireless cards to help select the transmission rate. Moreover, unlike previous approaches CHARM leverages channel reciprocity to obtain channel information, so the information is available to the transmitter without incurring RTS/CTS overhead. This combination of techniques allows CHARM to respond quickly to dynamic channel changes. We implemented CHARM in the Madwifi driver for wireless cards using the Atheros chipset. Our evaluation both in the real world and on a controlled testbed shows that channel-aware rate selection can significantly outperform probe-based rate adaptation, especially over dynamic channels.\",\n \"Title: A Signaling Protocol For Structured Resource Allocation\\nYear: 1999\\n\\nAbstract: There is an emerging class of multi-party, multimedia, multi-dow applications that have a high-level structure that imposes dependencies between resource allocations for flows within the application. These applications are also capable of making intelligent decisions on how resource allocation should be controlled within the application. The development of such applications places new requirements on signaling protocols. This paper outlines these new requirements, discusses ways in which they can be supported and presents the design and implementation of an experimental signaling protocol that supports these requirements.This paper makes the case that for these structured applications, there is an advantage to allocating the resources in an integrated fashion, i.e computation, storage and communication resources for all the Rows are allocated at the same time in a coordinated fashion. The concept of a virtual mesh is introduced as a key abstraction that encapsulates the set of resources that are allocated and managed in an integrated fashion to meet the needs of applications. The paper presents two mesh setup algorithms and a performance evaluation comparing them. Temporal resource sharing within the virtual mesh is discussed in detail and signaling support for temporal sharing at setup and runtime is examined. It is important to characterize temporal sharing since it can significantly reduce the resource requirements for applications.We have implemented the Beagle signaling protocol that supports this integrated resource management model. Beagle representations and mechanisms for mesh setup and temporal sharing are described and a prototype implementation is presented.\",\n \"Title: Routing high-bandwidth traffic in max-min fair share networks\\nYear: 1996\\n\\nAbstract: We study how to improve the throughput of high-bandwidth traffic such as large file transfers in a network where resources are fairly shared among connections. While it is possible to devise priority or reservation-based schemes that give high-bandwidth traffic preferential treatment at the expense of other connections, we focus on the use of routing algorithms that improve resource allocation while maintaining max-min fair share semantics. In our approach, routing is closely coupled with congestion control in the sense that congestion information, such as the rates allocated to existing connections, is used by the routing algorithm. To reduce the amount of routing information that must be distributed, an abstraction of the congestion information is introduced. Using an extensive set of simulation, we identify a link-cost or cost metric for \\\"shortest-path\\\" routing that performs uniformly better than the minimal-hop routing and shortest-widest path routing algorithms. To further improve throughput without reducing the fair share of single-path connections, we propose a novel prioritized multi-path routing algorithm in which low priority paths share the bandwidth left unused by higher priority paths. This leads to a conservative extension of max-min fairness called prioritized multi-level max-min fairness. Simulation results confirm the advantages of our multi-path routing algorithm.\",\n \"Title: When are directional antennas useful in indoor environments\\nYear: 2011\\n\\nAbstract: Directional antenna systems can provide two benefits 1) improve signal strength and increase communication range, and 2) improve spatial reuse. Recent work has drawn contradicting conclusions in terms of which of the two benefits dominates in indoor environments. These contradicting conclusions are in fact caused by different levels of contention within the environments used in these studies, i.e., noise-dominated vs. interference-dominated. In this paper, we first show that due to emerging applications and technologies, wireless networks are becoming interference-dominated, and thus the ability of the directional antennas to improve spatial reuse is becoming critical. Evaluating the benefits of spatial reuse, however, is difficult especially in indoor environments where multipath have both good and bad effect on spatial reuse. In this paper, we use the separation metric to estimate the effectiveness of directional transmission and guide the placement of directional APs in any particular environment. The separation metric summarizes both the angular and the distance separation for a collection of transmissions in a particular environment. We show that this metric, though simple, is powerful enough to capture the various properties of the deployment and the potential interactions among the directional transmissions. Our experimental results show in several scenarios that the separation metric works well in practice.\",\n \"Title: Automatic Selection Of Load Balancing Parameters Using Compile-Time And Run-Time Information\\nYear: 1997\\n\\nAbstract: Clusters of workstations are emerging as an important architecture. Programming tools that aid in distributing applications on workstation clusters must address problems of mapping the application, heterogeneity and maximizing system utilization in the presence of varying resource availability. Both computation and communication capabilities may vary with time due to other applications competing for resources, so dynamic load balancing is a key requirement. For greatest benefit, the tool must support a relatively wide class of applications running on clusters with a range of computation and communication capabilities. We have developed a system that supports dynamic load balancing of distributed applications consisting of parallelized DOALL and DOACROSS loops. The focus of the paper is on how the system automatically determines key load balancing parameters using run-time information and information provided by programming tools such as a parallelizing compiler. The parameters discussed are the grain size of the application, the frequency of load balancing, and the parameters that control work movement. Our results are supported by measurements on an implementation for the Nectar system at Carnegie Mellon University and by simulation. (C) 1997 by John Wiley & Sons, Ltd.\",\n \"Title: Design and Evaluation of a Hybrid Physical Space Service for Pervasive Computing Applications\\nYear: 2007\\n\\nAbstract: In this paper we present the design and implementation of a space service that gives pervasive computing applications both a hierarchical and coordinate-based view of physical space. The space service supports both indoor and outdoor campus environments and, besides relational and coordinate space information, it also gives information on how spaces are connected and relevant properties of spaces. We also evaluate the effectiveness of our design using a set of diverse applications, including finding the best \\\"walking\\\" path between two locations, giving walking directions to people, WiFi-based localization, and drawing and annotating maps. We have found that all of our applications depend on both the hierarchical and coordinate views offered by the service, suggesting that the hybrid space model is a very powerful paradigm.\",\n \"Title: Protecting Access to People Location Information\\nYear: 2003\\n\\nAbstract: Ubiquitous computing provides new types of information for which access needs to be controlled. For instance, a person's current location is a sensitive piece of information, and only authorized entities should be able to learn it. We present several challenges that arise for the specification and implementation of policies controlling access to location information. For example, there can be multiple sources of location information, policies need to be flexible, conflicts between policies might occur, and privacy issues need to be taken into account. Different environments handle these challenges in a different way. We discuss the challenges in the context of a hospital and a university environment. We show how our design of an access control mechanism for a system providing people location information addresses the challenges. Our mechanism can be deployed in different environments. We demonstrate feasibility of our design with an example implementation based on digital certificates.\",\n \"Title: Locating internet bottlenecks: algorithms, measurements, and implications\\nYear: 2004\\n\\nAbstract: The ability to locate network bottlenecks along end-to-end paths on the Internet is of great interest to both network operators and researchers. For example, knowing where bottleneck links are, network operators can apply traffic engineering either at the interdomain or intradomain level to improve routing. Existing tools either fail to identify the location of bottlenecks, or generate a large amount of probing packets. In addition, they often require access to both end points. In this paper we present Pathneck, a tool that allows end users to efficiently and accurately locate the bottleneck link on an Internet path. Pathneck is based on a novel probing technique called Recursive Packet Train (RPT) and does not require access to the destination. We evaluate Pathneck using wide area Internet experiments and trace-driven emulation. In addition, we present the results of an extensive study on bottlenecks in the Internet using carefully selected, geographically diverse probing sources and destinations. We found that Pathneck can successfully detect bottlenecks for almost 80% of the Internet paths we probed. We also report our success in using the bottleneck location and bandwidth bounds provided by Pathneck to infer bottlenecks and to avoid bottlenecks in multihoming and overlay routing.\",\n \"Title: Rainbow: Architecture-Based Self-Adaptation with Reusable Infrastructure\\nYear: 2004\\n\\nAbstract: Software-based systems today operate in changing environments and are subject to increasing administrative overhead. To reduce these costs, systems must dynamically self-adapt to accommodate resource variability, user needs, and system faults. The existing internal mechanisms that supportself-adaptation are often highly specific to the application and tightly bound to the code.In principle, external control mechanisms are more effective for self-adaptation because they localize the concerns of problem detection and resolution in separable modules that can be analyzed, modified, extended, and reused across different systems. The Rainbow framework adopts an architecture-based approach to provide a reusable infrastructure and mechanisms for specializing the infrastructure to the needs of specific systems.\",\n \"Title: Rainbow: architecture-based self-adaptation with reusable infrastructure\\nYear: 2004\\n\\nAbstract: Software-based systems today are increasingly expected to dynamically self-adapt to accommodate resource variability, changing user needs, and system faults. Recent work uses closed-loop control based on external models to monitor and adapt system behavior at run time. Taking this externalized approach, the Rainbow framework we have developed uses software architectural models to dynamically monitor and adapt a running system. A key goal and primary challenge of this framework is to support the reuse of adaptation strategies and infrastructure across different systems. We show that the separation of a generic adaptation infrastructure from system-specific adaptation knowledge makes this reuse possible.\",\n \"Title: Exploiting internet route sharing for large scale available bandwidth estimation\\nYear: 2005\\n\\nAbstract: Recent progress in active measurement techniques has made it possible to estimate end-to-end path available bandwidth. However, how to efficiently obtain available bandwidth information for the N2 paths in a large N-node system remains an open problem. While researchers have developed coordinate-based models that allow any node to quickly and accurately estimate latency in a scalable fashion, no such models exist for available bandwidth. In this paper we introduce BRoute--a scalable available bandwidth estimation system that is based on a route sharing model. The characteristics of BRoute are that its overhead is linear with the number of end nodes in the system, and that it requires only limited cooperation among end nodes. BRoute leverages the fact that most Internet bottlenecks are on path edges, and that edges are shared by many different paths. It uses AS-level source and sink trees to characterize and infer path-edge sharing in a scalable fashion. In this paper, we describe the BRoute architecture and evaluate the performance of its components. Initial experiments show that BRoute can infer path edges with an accuracy of over 80%. In a small case study on Planetlab, 80% of the available bandwidth estimates obtained from BRoute are accurate within 50%.\",\n \"Title: Catnap: exploiting high bandwidth wireless interfaces to save energy for mobile devices\\nYear: 2010\\n\\nAbstract: Energy management is a critical issue for mobile devices, with network activity often consuming a significant portion of the total system energy. In this paper, we propose Catnap, a system that reduces energy consumption of mobile devices by allowing them to sleep during data transfers. Catnap exploits high bandwidth wireless interfaces -- which offer significantly higher bandwidth compared to available bandwidth across the Internet -- by combining small gaps between packets into meaningful sleep intervals, thereby allowing the NIC as well as the device to doze off. Catnap targets data oriented applications, such as web and file transfers, which can afford delay of individual packets as long as the overall transfer times do not increase. Our evaluation shows that for small transfers (128kB to 5MB), Catnap allows the NIC to sleep for up to 70% of the total transfer time and for larger transfers, it allows the whole device to sleep for a significant fraction of the total transfer time. This results in battery life improvement of up to 2-5x for real devices like Nokia N810 and Thinkpad T60.\",\n \"Title: Airshed pollution modeling in an HPF style environment\\nYear: 2000\\n\\nAbstract: In this paper, we describe our experience with developing Airshed, a large pollution modeling application, in the Fx programming environment. We demonstrate that high level parallel programming languages like Fx and High Performance Fortran offer a simple and attractive model for developing portable and efficient parallel applications. Performance results are presented for the Airshed application executing on Intel Paragon and Cray T3D and T3E parallel computers. The results demonstrate that the application is \\\"performance portable\\\", i.e., it achieves good and consistent performance across different architectures, and that the performance can be explained and predicted using a simple model for the communication and computation phases in the program. We also show how task parallelism was used to alleviate I/O related bottlenecks, an important consideration in many applications. Finally, we demonstrate how external parallel modules developed using different parallelization methods can be integrated in a relatively simple and flexible way with modules developed in the Fx compiler framework. Overall, our experience demonstrates that a high level parallel programming environment based on a language like HPF is suitable for developing complex multidisciplinary applications.\",\n \"Title: Access control to information in pervasive computing environments\\nYear: 2003\\n\\nAbstract: Many types of information available in a pervasive computing environment, such as people location information, should be accessible only by a limited set of people. Some properties of the information raise unique challenges for the design of an access control mechanism: Information can emanate from more than one source, it might change its nature or granularity before reaching its final receiver, and it can flow through nodes administrated by different entities. We propose three design principles for the architecture of an access control mechanism: (1) extract pieces of information in raw data streams early, (2) define policies controlling access at the information level, and (3) exploit information relationships for access control. We describe an example architecture in which we apply these principles. We also report how our earlier work about adding access control to a people location service contributed to the more general access control architecture proposed here.\",\n \"Title: Network-Scale Emulation Of General Wireless Channels\\nYear: 2011\\n\\nAbstract: This paper presents a framework for signal-level emulation of propagation effects over generalized fading channels at the scale of entire networks. Network emulation enables research into network-scale systems - which would otherwise be limited to low-fidelity network simulators and one-off field experiments - to use real radio hardware and realistic channel models. Our hardware and software architecture goes beyond previous work in that it supports real-time emulation of a very general and parametric class of channels, which includes vehicular (broadband mobile-to-mobile) and indoor channels in addition to classical stationary-to-mobile and stationary-to-stationary channels.\",\n \"Title: Avoiding Privacy Violations Caused by Context-Sensitive Services\\nYear: 2006\\n\\nAbstract: The increasing availability of information about people's context makes it possible to deploy context-sensitive services, where access to resources provided or managed by a service is limited depending on a person's context. For example, a location-based service can require an individual to be at a particular location in order to let the individual use a printer or learn her friends' location. However, constraining access to a resource based on confidential information about a person's context could result in privacy violations. For instance, if access is constrained based on a person's location, granting or rejecting access will provide information about this person's location and could violate the person's privacy. We introduce an access-control algorithm that avoids privacy violations caused by context-sensitive services. Our algorithm exploits the concepts of access-rights graphs, which represent all the information that needs to be collected in order to make a context-sensitive access decision. Moreover, we introduce hidden constraints, which keep some of this information secret and thus allow for more flexible access control. We present a distributed, certificate-based access-control architecture for context-sensitive services that avoids privacy violations, a sample implementation, and a performance evaluation\",\n \"Title: Analysis of the reputation system and user contributions on a question answering website: StackOverflow\\nYear: 2013\\n\\nAbstract: Question answering (Q&A) communities have been gaining popularity in the past few years. The success of such sites depends mainly on the contribution of a small number of expert users who provide a significant portion of the helpful answers, and so identifying users that have the potential of becoming strong contributers is an important task for owners of such communities. We present a study of the popular Q&A website StackOverflow (SO), in which users ask and answer questions about software development, algorithms, math and other technical topics. The dataset includes information on 3.5 million questions and 6.9 million answers created by 1.3 million users in the years 2008--2012. Participation in activities on the site (such as asking and answering questions) earns users reputation, which is an indicator of the value of that user to the site. We describe an analysis of the SO reputation system, and the participation patterns of high and low reputation users. The contributions of very high reputation users to the site indicate that they are the primary source of answers, and especially of high quality answers. Interestingly, we find that while the majority of questions on the site are asked by low reputation users, on average a high reputation user asks more questions than a user with low reputation. We consider a number of graph analysis methods for detecting influential and anomalous users in the underlying user interaction network, and find they are effective in detecting extreme behaviors such as those of spam users. Lastly, we show an application of our analysis: by considering user contributions over first months of activity on the site, we predict who will become influential long-term contributors.\",\n \"Title: Effects of buffering semantics on I/O performance\\nYear: 1996\\n\\nAbstract: No abstract available.\",\n \"Title: A time-based adaptive retry strategy for video streaming in 802.11 WLANs\\nYear: 2007\\n\\nAbstract: Video streaming over time-varying, error-prone wireless LANs (WLANs) poses many challenges. One problem is that WLANs are designed without awareness of the characteristics of application data, which causes performance degradation in a noisy or congested environment. In this paper, we propose a time-based adaptive retry (TAR) mechanism for MPEG-like video streaming over 802.11 wireless networks. TAR dynamically determines whether to send or discard a packet based on its retransmission deadline instead of adopting a static retry limit uniformly over all the packets. Our approach can adapt the retry limit for each individual packet, thus providing indirect unequal error protection over different types of video frames. Analytical and simulation results show that TAR significantly improves video quality and saves channel bandwidth. We also describe a preliminary software-based implementation of TAR and use it to demonstrate the practicality of the proposed approach. Copyright (c) 2007 John Wiley & Sons, Ltd.\",\n \"Title: Securing information gateways with derivation-constrained access control\\nYear: 2006\\n\\nAbstract: In pervasive computing environments, information gateways derive specific information, such as a person's location, from raw data provided by a service, such as a videostream offered by a camera. Here, access control to confidential raw data provided by a service becomes difficult when a client does not have access rights to this data. For example, a client might have access to a person's location information, but not to the videostream from which a gateway derives this information. Simply granting access rights to a gateway will allow an intruder into the gateway to access any raw data that the gateway can access. We present the concept of derivation-constrained access control, which requires a gateway to prove to a service that the gateway needs requested raw data to answer a client's authorized request for derived information. Therefore, an intruder into the gateway will be limited in its capabilities. We provide a formal framework for derivation-constrained access control based on Lampson et al.'s “speaks-for” relationship. We demonstrate feasibility of our design with a sample implementation and a performance evaluation.\",\n \"Title: Network-Based Multicomputers: A Practical Supercomputer Architecture\\nYear: 1996\\n\\nAbstract: Multicomputers built around a general network are an attractive architecture for a wide class of applications. The architecture provides many benefits compared with special-purpose approaches, including heterogeneity, reuse of application and system code, and sharing of resources. The architecture also poses new challenges to both computer system implementors and users. First, traditional local-area networks do not have enough bandwidth and create a communication bottleneck, thus seriously limiting the set of applications that can be run effectively. Second, programmers have to deal with large bodies of code distributed over a variety of architectures, and work in an environment where both the network and nodes are shared with other users. Our experience in the Nectar project shows that it is possible to overcome these problems. We show how networks based on high-speed crossbar switches and efficient protocol implementations can support high bandwidth and low latency communication while still enjoying the flexibility of general networks, and we use three applications to demonstrate that network-based multicomputers are a practical architecture. We also show how the network traffic generated by this new class of applications poses severe requirements for networks.\",\n \"Title: Network-based multicomputers: an emerging parallel architecture\\nYear: 1991\\n\\nAbstract: No abstract available\",\n \"Title: XIA: efficient support for evolvable internetworking\\nYear: 2012\\n\\nAbstract: Motivated by limitations in today's host-centric IP network, recent studies have proposed clean-slate network architectures centered around alternate first-class principals, such as content, services, or users. However, much like the host-centric IP design, elevating one principal type above others hinders communication between other principals and inhibits the network's capability to evolve. This paper presents the eXpressive Internet Architecture (XIA), an architecture with native support for multiple principals and the ability to evolve its functionality to accommodate new, as yet unforeseen, principals over time. We describe key design requirements, and demonstrate how XIA's rich addressing and forwarding semantics facilitate flexibility and evolvability, while keeping core network functions simple and efficient. We describe case studies that demonstrate key functionality XIA enables.\",\n \"Title: Robust wireless video streaming using hybrid spatial/temporal retransmission\\nYear: 2010\\n\\nAbstract: Bandwidth demands and timing constraints are two major challenges for wireless video streaming applications. In this paper, we present a hybrid spatial/temporal retransmission protocol that tackles both of these challenges. To increase individual throughput as well as overall network capacity, the system uses an opportunistic retransmission protocol (PRO, Protocol for Retransmitting Opportunistically) that relies on overhearing nodes distributed in physical space to function as relays that retransmit failed packets on behalf of the source. Specifically, the best relay out of the set of nodes that currently have the copy of the packet is responsible for retransmitting (relaying) the packet. Relays with stronger connectivity to the destination have a higher chance of delivering packets successfully than the source, thereby resulting in a more efficient use of the channel. To meet timing constraints, a Time-based Adaptive Retransmission strategy (TAR) is applied by both the source and the relays. With TAR, the MAC dynamically determines whether to (re)transmit or discard a packet based on the retransmission deadline of the packet assigned by the video server. This significantly reduces the number of late packet arrivals at the receiver. Our extensive evaluation results both on a testbed and in the real world demonstrate that hybrid temporal/spatial retransmission can boost streaming performance in diverse wireless environments. The benefits are most pronounced for busy networks, under fading conditions, or for mobile users.\",\n \"Title: Architecting for edge diversity: supporting rich services over an unbundled transport\\nYear: 2012\\n\\nAbstract: The end-to-end nature of today's transport protocols is increasingly being questioned by the growing heterogeneity of networks and devices, and the need to support in-network services. To address these challenges, we present Tapa, a transport architecture that systematically combines two concepts. First, it unbundles today's transport such that network specific functions (e.g., congestion control) are implemented on a per-segment basis, where a segment spans a part of the end-to-end path that is homogeneous (e.g., wired Internet or an access network) while functions that relate to application semantics (e.g., data ordering) are still implemented end-to-end. Second, it has an explicit notion of in-network services (e.g., caching, opportunistic content retrieval, etc) that can be supported while maintaining precise end-to-end application semantics. In this paper, we present the basic design, implementation and evaluation of Tapa. We also present diverse case studies that show how Tapa can easily support opportunistic content retrieval in online social networks, various mobile and wireless optimizations, and an in-network energy saving service that improves battery life of mobile devices.\",\n \"Title: Measurement and analysis of the error characteristics of an in-building wireless network\\nYear: 1996\\n\\nAbstract: There is general belief that networks based on wireless technologies have much higher error rates than those based on more traditional technologies such as optical fiber, coaxial cable, or twisted pair wiring. This difference has motivated research on new protocol suites specifically for wireless networks. While the error characteristics of wired networks have been well documented, less experimental data is available for wireless LANs.In this paper we report the results of a study characterizing the error environment provided by AT&T WaveLAN, a commercial product designed for constructing 2 Mb/s in-building wireless networks. We evaluated the effects of interfering radiation sources, and of attenuation due to distance and obstacles, on the packet loss rate and bit error rate. We found that under many conditions the error rate of this physical layer is comparable to that of wired links. We analyze the implications of our results on today's CSMA/CA based wireless LANs and on future pico-cellular shared-medium reservation-based wireless networks.\",\n \"Title: Enabling MAC protocol implementations on software-defined radios\\nYear: 2009\\n\\nAbstract: Over the past few years a range of new Media Access Control (MAC) protocols have been proposed for wireless networks. This research has been driven by the observation that a single one-size-fits-all MAC protocol cannot meet the needs of diverse wireless deployments and applications. Unfortunately, most MAC functionality has traditionally been implemented on the wireless card for performance reasons, thus, limiting the opportunities for MAC customization. Software-defined radios (SDRs) promise unprecedented flexibility, but their architecture has proven to be a challenge for MAC protocols. In this paper, we identify a minimum set of core MAC functions that must be implemented close to the radio in a high-latency SDR architecture to enable high performance and efficient MAC implementations. These functions include: precise scheduling in time, carrier sense, backoff, dependent packets, packet recognition, fine-grained radio control, and access to physical layer information. While we focus on an architecture where the bus latency exceeds common MAC interaction times (tens to hundreds of microseconds), other SDR architectures with lower latencies can also benefit from implementing a subset of these functions closer to the radio. We also define an API applicable to all SDR architectures that allows the host to control these functions, providing the necessary flexibility to implement a diverse range of MAC protocols. We show the effectiveness of our split-functionality approach through an implementation on the GNU Radio and USRP platforms. Our evaluation based on microbenchmarks and end-to-end network measurements, shows that our design can simultaneously achieve high flexibility and high performance.\",\n \"Title: Using commodity hardware platform to develop and evaluate CSMA protocols\\nYear: 2008\\n\\nAbstract: Developing and evaluating wireless protocols is challenging because it requires flexible network interface hardware, which is not readily available. In this paper, we present FlexMAC, a wireless protocol development and evaluation platform based on commodity hardware. FlexMAC targets CSMA wireless protocols and allows customization of functions such as backoff, retransmission, and packet timing. We describe our implementation of FlexMAC and quantify FlexMAC's precision for 802.11b compared with commercial hardware implementations. The results show that FlexMAC's performance is very close to that of hardware implementations. We also present two case studies that illustrate FlexMAC's flexibility: the use of opportunistic relaying to boost throughput and an investigation of temporal and throughput fairness. We found that FlexMAC is a useful tool for conducting 802.11-style protocol research.\",\n \"Title: An Adaptive Protocol for Efficient Support of Range Queries in DHT-Based Systems\\nYear: 2004\\n\\nAbstract: In recent years, Distributed Hash Tables (DHTs) have been proposed as a fundamental building block for large scale distributed applications. Important functionalities such as searching have been added to the DHT's basic lookup capability. However, supporting range queries efficiently remains a difficult problem. In this paper, we describe an adaptive mechanism that relies on a logical tree data structure, the Range Search Tree (RST), to support range queries efficiently. Nodes in the RST automatically group registrations based on their values. Queries are decomposed into a small number of sub-queries for efficient resolution. The system dynamically optimizes itself to minimize the registration and query cost based on observed load. The system is fully distributed and avoids bottleneck problems encountered in traditional tree-based systems. Extensive simulation results validate the effectiveness of the system.\",\n \"Title: Adaptation Models for Network-Aware Distributed Computations\\nYear: 1999\\n\\nAbstract: Network-aware applications actively adapt to the level of service they receive from the network. This allows the application\\n to execute well over a diverse set of networks and under a wide range of network conditions. However, network diversity and\\n dynamic network conditions make the development of network-aware applications a difficult task, since the developer has to\\n be an expert in both the application domain and networking. In this paper we look at a number of network-aware applications\\n and identify three adaptation strategies that have proven to be effective. These strategies can be viewed as adapation models\\n that capture the essential structure of the adaptation process. Similar to the use of programming models in parallel and distributed\\n computing, adaptation models can be used to guide the development of other network-aware applications and they can also form\\n the basis for programming support, e.g. middleware, that supports the development of network-aware applications. In this paper\\n we describe the three adaptation models, compare their features and applicability, and briefly discuss how these models impact\\n the design of middleware that supports network-aware applications.\",\n \"Title: Exploiting Hierarchical Identity-Based Encryption for Access Control to Pervasive Computing Information\\nYear: 2005\\n\\nAbstract: Access control to confidential information in pervasive computing environments is challenging for multiple reasons: First, a client requesting access might not know which access rights are necessary in order to be granted access to the requested information. Second, access control must support flexible access rights that include context-sensitive constraints. Third, pervasive computing environments consist of a multitude of information services, which makes simple management of access rights essential. We discuss the shortcomings of existing access-control schemes that rely on either clients presenting a proof of access to a service or services encrypting information before handing the information over to a client. We propose a proofbased access-control architecture that employs hierarchical identity-based encryption in order to enable services to inform clients of the required proof of access in a covert way, without leaking information. Furthermore, we introduce an encryption-based access-control architecture that exploits hierarchical identity-based encryption in order to deal with multiple, hierarchical constraints on access rights. We present an example implementation of our proposed architectures and discuss the performance of this implementation.\",\n \"Title: Understanding 802.11 performance in heterogeneous environments\\nYear: 2011\\n\\nAbstract: The availability of unlicensed spectrum coupled with the increasing popularity of wireless communication has given rise to a diverse range of wireless technologies that compete for spectrum. In particular, 802.11 devices face a host of problems such as interference with other 802.11 devices (hidden terminals) as well as with technologies like Bluetooth and ZigBee. Understanding how the medium is utilized and inferring the cause of interference, based on observations from a single wireless node, is hard. Past work has used monitoring infrastructures to detect interference between 802.11 nodes in enterprise networks. In this paper, we try to answer the question: \\\"how can we enable users to reason about wireless performance variations without requiring elaborate instrumentation and infrastructure support?\\\". We propose WiMed, a tool that uses only local measurements from commodity 802.11 NICs (at the node being diagnosed) to construct a time map of how the medium is utilized. We have implemented a WiMed prototype using the MadWifi driver for Atheros NICs. Early results show that WiMed is useful and can characterize non-802.11 interference better than existing systems.\",\n \"Title: The Architecture of the Remos System\\nYear: 2001\\n\\nAbstract: Abstract: Remos provides resource information to distributed applications. Its design goals of scalability, flexibility, and portability are achieved through an architecture that allows components to be positioned across the network, each collecting information about its local network. To collect information from different types of networks and from hosts on those networks, Remos provides several collectors that use different technologies, such as SNMP or benchmarking. By matching the appropriate collector to each particular network environment and by providing an architecture for distributing the output of these collectors across all querying environments, Remos collects appropriately detailed information at each site and distributes this information where needed in a scalable manner. Prediction services are integrated at the user-level, allowing history-based data collected across the network to be used to generate the predictions needed by a particular user. Remos has been implemented and tested in a variety of networks and is in use in a number of different environments.\",\n \"Title: Future of multi-hopping: from theory to practice\\nYear: 2009\\n\\nAbstract: The research community has been fascinated by the challenges posed by multi-hopping for over a decade, and has produced a number of interesting theoretical results and innovative solutions for many of these challenges. However, despite the plethora of envisioned applications for many multi-hop architectures, e.g. mesh, sensor, and ad-hoc, the reality is that there are only a few real-world success stories involving multi-hopping. The panel plans to discuss how we can move more effectively from theory to practice, and debate whether it is a matter of time for more real-world applications to materialize, or cost-related and other real-world considerations will restrict the use of multi-hopping to only a few specialized applications.\",\n \"Title: A high-speed network interface for distributed-memory systems: architecture and applications\\nYear: 1997\\n\\nAbstract: Distributed-memory systems have traditionally had great difficulty performing network I/O at rates proportional to their computational power. The problem is that the network interface has to support network I/O for a supercomputer, using computational and memory bandwidth resources similar to those of a workstation. As a result, the network interface becomes a bottleneck. In this article we present an I/O architecture that addresses these problems and supports high-speed network I/O on distributed-memory systems. The key to good performance is to partition the work appropriately between the system and the network interface. Some communication tasks are performed on the distributed-memory parallel system, since it is more powerful and less likely to become a bottleneck than the network interface. Tasks that do not parallelize well are performed on the network interface, and hardware support is provided for the most time-critical operations. This architecture has been implemented for the iWarp distributed-memory system and has been used by a number of applications. We describe this implementaiton, present performance results, and use application examples to validated the main features of the I/O architecture.\",\n \"Title: FlexMAC: a wireless protocol development and evaluation platform based on commodity hardware\\nYear: 2008\\n\\nAbstract: Developing and evaluating wireless protocols is challenging because it requires flexible network interface hardware, which is not readily available. To reduce the efforts of conducting realistic wireless experiment, we have developed FlexMAC, a wireless protocol development and evaluation platform based on commodity hardware. FlexMAC targets CSMA wireless protocols and allows customization of functions such as backoff, retransmission, and packet timing. In this demo, we will show that FlexMAC is a useful tool for wireless protocol development. We will demonstrate two projects that are developed using FlexMAC, including a software-based 802.11 implementation and an opportunistic relaying protocol in 802.11.\",\n \"Title: A Host Interface Architecture for High-Speed Networks\\nYear: 1992\\n\\nAbstract: This paper describes a new host interface architecture for high-speed networks operating at 800 of Mbit/second or higher rates. The architecture is targeted to achieve several 100s of Mbit/second application-to-application performance for a wide range of host architectures. The architecture achieves the goal by providing a streamlined execution environment for the entire path between host application and network interface. In particular, a “Communication Accelerator Block” (CAB) is used to minimize data copies, reduce host interrupts, support DMA and hardware checksumming, and control network access. This host architecture is applicable to a large class of hosts with high-speed I/O busses. Two implementations for the 800 Mbit/second HIPPI network are under development. One is for a distributed-memory supercomputer (iWarp) and the other is for a high-performance workstation (DECstation 5000). We describe and justify both implementations. Keyword Codes: B.4.1; C.2.1\",\n \"Title: Architecture implications of high-speed I/O for distributed-memory computers\\nYear: 1994\\n\\nAbstract: We consider the problem of high-speed I/O for a single application running on multiple nodes of a distributed-memory parallel computer. Our model is that the parallel system is connected to an I/O system that provides the interface between the internal connections of the parallel system and one or more external connections, such as HIPPI links. We identify two primary operations for this I/O system: scattering data from a high speed link across several lower speed links and gathering data from multiple links onto a single high speed link. We show that these core operations are the basis of the I/O system, independent of the relative speeds of the internal and external connections.We identify several architectural features that are critical for supporting high-speed scatter and gather operations. They include flexible routing methods in the parallel system, low overhead communication, and the ability to support multiple data streams in and out of the memory on the I/O node.\",\n \"Title: Video Streaming Over 802.11 WLAN with Content-Aware Adaptive Retry\\nYear: 2005\\n\\nAbstract: Robust video streaming over error-prone wireless LANs (WLANs) poses many challenges. In this paper, we propose a timestamp-based content-aware adaptive retry (CAR) mechanism for MPEG video streaming over 802.11 WLANs, where the MAC dynamically determines whether to send or discard a packet based on its retransmission deadline. The retransmission deadline is assigned to each packet according to its temporal relationship and error propagation characteristics with respect to other video packets in the same GOP. The proposed scheme avoids late packets by eliminating the impact of random backoff deference and co-channel interference with proper initial delay introduced at the receiver. Simulation results show CAR significantly improves video quality and saves channel bandwidth\",\n \"Title: Adaptive filtering of MPEG system streams in IP networks\\nYear: 2006\\n\\nAbstract: Congestion and large differences in available link bandwidth create challenges for the design of applications that want to deliver high quality video over the Internet. We present an efficient adaptive filter for MPEG System streams that can be placed in the network (e.g., as an active service). This filter adjusts the bandwidth demands of an MPEG System stream to the available bandwidth without transcoding while maintaining synchronization between the streams embedded in the MPEG System. The filter is network-friendly: it is fair with respect to other (TCP) competing streams and it avoids generating bursty traffic. This paper presents the system architecture and an evaluation of our implementation in three different operating environments: a networking testbed in a laboratory environment, a home-user scenario (DSL line with 640 Kbit/s), and a wide area network covering the Atlantic (server in Europe, client in the US). Moreover we examine the network-friendliness of the adaptation protocol and the relationship between the quality of the received continuous media and the protocol's aggressiveness. Our architecture is based on efficient MPEG System filtering to achieve high-quality video over best-effort networks.\",\n \"Title: RFDump: an architecture for monitoring the wireless ether\\nYear: 2009\\n\\nAbstract: Networking researchers have been using tools like wireshark and tcpdump to sniff packets on physical links that use different types of datalink protocols, e.g. Ethernet or 802.11, allowing them to monitor higher level protocols sharing these links. However, monitoring wireless links is more challenging, since the transmission medium is shared by flows using diverse datalink protocols (e.g. 802.11, Bluetooth) and physical layer schemes (e.g. QPSK and GFSK). To this end, we propose RFDump, a software architecture for monitoring packets on heterogeneous wireless networks. The key idea underlying our architecture is the use of a fast detection stage which can tentatively map signals to protocols very efficiently. As a result, RFDump can scale up to a modest number (5-10) of wireless technologies. We implemented RFDump on the GNU Radio and USRP platforms. This is, to our knowledge, the first inexpensive software-based infrastructure for simultaneously analyzing multiple wireless protocols in real-time. Using traces from the real world and from a wireless emulator testbed, we show that our implementation is efficient and accurate. Further, we demonstrate that our system is extensible and scales with the addition of new protocols.\",\n \"Title: A trace-based evaluation of adaptive error correction for a wireless local area network\\nYear: 1999\\n\\nAbstract: Wireless transmissions are highly susceptible to noise and interference. As a result, the error characteristics of a wireless link may vary widely depending on environmental factors such as location of the communicating systems and activity of competing radiation sources, making error control a difficult task. In this paper we evaluate error control strategies for a wireless LAN. Based on low-level packet traces of WaveLAN, we first show that forward error correction (FEC) is effective in recovering from bit corruptions and that packet length adjustment can reduce packet truncation. However, as expected, fixed error control policies can perform very poorly, because they either introduce too much overhead in “good” environments or are not aggressive enough in “bad” environments. We address this problem through adaptive error control, i.e., error control policies that adapt the degree of FEC redundancy and the packet size to the environment. The effectiveness of adaptive error control depends on the characteristics of the error environment, e.g., the type of errors and the frequency with which the error environment changes. Our evaluation shows that adaptive error control can improve throughput consistently across a wide range of wireless LAN error environments. The reason for this effectiveness is that changes in the error environemtn are often caused by human mobility-related events such as the motion of a cordless phone, which take place over seconds, while adaptation protocols can respond in tens of milliseconds. Evaluating adaptive error control in a wireless environments is challenging because repeatable experiments are difficult: the wireless environment cannot easily be isolated and the adaptation process itself changes the environment, which may make trace-based evaluation difficult. We introduce a trace-based evaluation methodology that deals appropriately with changes in packet content and size.\",\n \"Title: Design And Implementation Of An Rf Front End For Physical Layer Wireless Network Emulation\\nYear: 2007\\n\\nAbstract: Networking researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we have developed a wireless network emulator that enables both realistic and repeatable experimentation at network scale. A critical component in this emulator is the RF Front End that converts RF signals to lower frequencies - where they can be digitized - and vice versa.We discuss the unique requirements that physical layer network emulation demands of an RF Front End. We present a design that meets these demands and demonstrate its performance via measurements.\",\n \"Title: Performance of circuit switched LANs under different traffic conditions\\nYear: 1994\\n\\nAbstract: Switched LANs are become more widely used because they can provide a higher bandwidth than LANs based on shared media. Examples of packet switched LANs include HIPPI, and switched FDDI and Ethernet. A number of studies have evaluated the performance of HIPPI networks, making simplifying assumptions about both the network and the traffic load. In this paper we present the results of a simulation study of circuit-switched LANs such as HIPPI using more realistic models for the system and the traffic. We observe changes in throughput as high as a factor of ten when we change the system and traffic parameters. We also show how packet scheduling can be used to improve performance in some cases\",\n \"Title: Improving the accuracy of environment-specific vehicular channel modeling\\nYear: 2012\\n\\nAbstract: Networking research benefits from the controlled, repeatable experimentation provided by simulation and emulation systems. Making such simulations realistic is a challenge for wireless systems and is especially difficult for vehicular networks. This paper introduces a realistic vehicular channel simulation model that includes a Line-Of-Sight (LOS) module and Vehicle-to-Vehicle (V2V) fading module specially designed for vehicular channels. Specialized models can provide a close approximation of real channel conditions, but their accuracy is limited by the quality of input information about the environment being modeled. In this paper, we present a systematic approach to estimate location-specific scattering properties using aerial photography. We show that this approach significantly improves the accuracy of simulated channel fading.\",\n \"Title: Evaluation Of Adaptive Filtering Of Mpeg System Streams In Ip Networks\\nYear: 2000\\n\\nAbstract: Congestion and large differences in available link bandwidth create challenges for the design of applications that want to deliver high quality video over the Internet. We investigate the placement of computation agents within the network to provide filtering to adapt MPEG system streams to the available bandwidth without transcoding. This paper presents an evaluation of our implementation in three different operating environments: a networking testbed in a laboratory environment, a home-user scenario (DSL line with 640 Kbit/sec), and a wide area network covering the Atlantic (server in Europe, client in the US). Our architecture leverages previous work and introduces efficient MPEG system filtering to achieve high-quality video over best-effort networks.\",\n \"Title: Improving TCP Startup Performance Using Active Measurements: Algorithm and Evaluation\\nYear: 2003\\n\\nAbstract: TCP Slow Start exponentially increases the congestion window size to detect the proper congestion window for a network path. This often results in significant packet loss, while breaking off Slow Start using a limited slow start threshold may lead to an overly conservative congestion window size. This problem is especially severe in high speed networks. In this paper we present a new TCP startup algorithm, called Paced Start, that incorporates an available bandwidth probing technique into the TCP startup algorithm. Paced Start is based on the observation that when we view the TCP startup sequence as a sequence of packet trains, the difference between the data packet spacing and the acknowledgement spacing can yield valuable information about the available bandwidth. Slow Start ignores this information, while Paced Start uses it to quickly estimate the proper congestion window for the path. For most flows, Paced Start transitions into congestion avoidance mode faster thanSlow Start, has a signi.cantly lower packet loss rate, and avoids the timeout that is often associated with Slow Start. This paper describes the Paced Start algorithm and uses simulation and real system experiments to characterize its properties.\",\n \"Title: Architecture and evaluation of a high-speed networking subsystem for distributed-memory systems\\nYear: 1994\\n\\nAbstract: Achieving high-speed network I/O on distributed-memory systems is difficult because their architecture is in general ill-suited for communication processing. Some of the common problems are: inability to do protocol processing, inefficient handling of data distribution, and poor management of the I/O. The authors present an I/O architecture that addresses these problems and supports high-speed network I/O on distributed-memory systems. The key to good performance is to partition the work appropriately between the system and the network interface. The authors perform some communication tasks on the distributed-memory parallel system since it is more powerful, and less likely to become a bottleneck than the network interface. Tasks that do not parallelize well are performed on the network interface and hardware support is provided for the most time-critical operations. They emphasize the use of simple I/O mechanisms that can be used by programming tools that map applications on the distributed-memory system to implement efficient I/O for the class of applications they support. This architecture has been implemented for the iWarp distributed-memory system. The authors describe this implementation and present performance results\",\n \"Title: Providing Contextual Information to Pervasive Computing Applications\\nYear: 2003\\n\\nAbstract: Pervasive computing applications are increasingly leveraging contextual information from several sources to provide users with behavior appropriate to the environment in which they reside. If these sources of contextual information are used and deployed in an ad hoc manner, however, they may provide overlapping functionality, fail to provide needed functionality, and require the use of inconsistent interfaces by applications. To overcome these problems, we introduce a Contextual Information Service that provides applications with contextual information via a virtual database. Unlike previous efforts, our service provides applications a consistent, lightweight, and powerful mechanism for obtaining contextual information, and includes explicit support for the on demand computation of contextual information. We show, via example applications and a Contextual Information Service prototype that we have implemented, how this approach can be used to allow proactive applications to adapt their behavior to match a user's current environment.\",\n \"Title: Time-Aware Opportunistic Relay For Video Streaming Over Wlans\\nYear: 2007\\n\\nAbstract: Robust video streaming over time-varying, error-prone wireless LANs (WLANs) poses many challenges. In this paper, we present a Time-based Opportunistic Relay (TOR) scheme for high-quality video streaming over WLANs. The proposed scheme exploits path diversity in relaying packets with awareness of the time constraints of video data. Specifically, relay nodes continuously overhear and opportunistically forward packets to enhance end-to-end delivery rates. To relay a packet in a time-aware manner, a relay deadline is computed for each packet and used by relay nodes to determine whether they should relay or discard the packet. Simulation results show that TOR improves video quality by up to 9.76 dB.\",\n \"Title: The use of a controlled wireless testbed in courses\\nYear: 2009\\n\\nAbstract: Wireless networking has become a popular topic in both undergraduate and graduate courses. However, putting together good assignments in wireless networking is difficult because the behavior of the wireless network depends strongly on the physical environment. We have used a wireless networking testbed based on signal propagation emulation in a number of wireless networking courses. The wireless emulator supports highly realistic experiments, while also offering a high degree of control and repeatability. This combination is very useful in a teaching context. In this paper we give an overview of the wireless emulator and we describe how it was used to support assignments and open-ended projects in several courses.\",\n \"Title: Self-management in chaotic wireless deployments\\nYear: 2007\\n\\nAbstract: Over the past few years, wireless networking technologies have made vast forays into our daily lives. Today, one can find 802.11 hardware and other personal wireless technology employed at homes, shopping malls, coffee shops and airports. Present-day wireless network deployments bear two important properties: they are unplanned, with most access points (APs) deployed by users in a spontaneous manner, resulting in highly variable AP densities; and they are unmanaged, since manually configuring and managing a wireless network is very complicated. We refer to such wireless deployments as being chaotic. In this paper, we present a study of the impact of interference in chaotic 802.11 deployments on end-client performance. First, using large-scale measurement data from several cities, we show that it is not uncommon to have tens of APs deployed in close proximity of each other. Moreover, most APs are not configured to minimize interference with their neighbors. We then perform trace-driven simulations to show that the performance of end-clients could suffer significantly in chaotic deployments. We argue that end-client experience could be significantly improved by making chaotic wireless networks self-managing. We design and evaluate automated power control and rate adaptation algorithms to minimize interference among neighboring APs, while ensuring robust end-client performance.\",\n \"Title: Can user-level probing detect and diagnose common home-WLAN pathologies\\nYear: 2012\\n\\nAbstract: Common Wireless LAN (WLAN) pathologies include low signal-to-noise ratio, congestion, hidden terminals or interference from non-802.11 devices and phenomena. Prior work has focused on the detection and diagnosis of such problems using layer-2 information from 802.11 devices and special purpose access points and monitors, which may not be generally available. Here, we investigate a user-level approach: is it possible to detect and diagnose 802.11 pathologies with strictly user-level active probing, without any cooperation from, and without any visibility in, layer-2 devices? In this paper, we present preliminary but promising results indicating that such diagnostics are feasible.\",\n \"Title: Gigabit I/O for distributed-memory machines: architecture and applications\\nYear: 1995\\n\\nAbstract: Distributed-memory systems have traditionally had great difficulty performing network I/O at rates proportional to their computational power. The problem is that the network interface has to support network I/O for a supercomputer, using computational and memory bandwidth resources similar to those of a workstation. As a result, the network interface becomes a bottleneck. We implemented an architecture for network I/O for the iWarp system with the following two key characteristics: first, application-specific tasks are off-loaded from the network interface to the distributed-memory system, and second, these tasks are performed in close cooperation with the application. The network interface has been used by several applications for over a year. In this paper we describe the network interface software that manages the communication between the iWarp distributed-memory system and the network interface, we validate the main features of our network interface architecture based on application experience, and we discuss how this architecture can be used by other distributed-memory systems.\",\n \"Title: Repeatable and realistic wireless experimentation through physical emulation\\nYear: 2004\\n\\nAbstract: In wireless networking research, there has long existed a fundamental tension between experimental realism on one hand, and control and repeatability on the other hand. Hardware-based experimentation provides realism, but is tightly coupled to the physical environment and circumstances under which experiments are carried out. To overcome this, researchers have understandably embraced simulation as a means of evaluation. Unfortunately, wireless simulation is plagued with inherent inaccuracies. To overcome the stark tradeoff between the realism of hardware-based experimentation and the repeatability of simulation-based experimentation, we are developing a wireless emulator that enables both realistic and repeatable experimentation. Unlike previous emulators, our approach simultaneously achieves both a high degree of realism and fine-grained repeatability by leveraging physical layer emulation.\",\n \"Title: Characterizing 802.11 wireless link behavior\\nYear: 2010\\n\\nAbstract: Since wireless signals propagate through the ether, they are significantly affected by attenuation, fading, multipath, and interference. As a result, it is difficult to measure and understand fundamental wireless network behavior. This creates a challenge for both network researchers, who often rely on simulators to evaluate their work, and network managers, who need to deploy and optimize operational networks. Given the complexity of wireless networks, both communities often rely on simplifying rules, which frequently have not been validated using today's wireless radios. In this paper, we undertake a detailed characterization of 802.11 link-level behavior using commercial 802.11 cards. Our study uses a wireless testbed that provides signal propagation emulation, giving us complete control over the signal environment. In addition, we use our measurements to analyze the performance of an operational wireless network. Our work contributes to a more accurate understanding of link-level behavior and enables the development of more accurate wireless network simulators.\",\n \"Title: Reclaiming the white spaces: spectrum efficient coexistence with primary users\\nYear: 2011\\n\\nAbstract: TV white spaces offer an exciting opportunity for increasing spectrum availability, but white space devices (WSDs) cannot interfere with primary users, including TV channels and wireless microphones (mics). Mics are particularly challenging because their use is dynamic and it is hard to avoid interference since mic receivers are receive-only devices. For this reason the FCC and other regulatory agencies have made very conservatives rules that require WSDs to vacate any TV channel that is used by a mic. However, our measurements show that mics typically require only 5% of a channel, wasting as much as 95% of the spectrum. We present SEISMIC, a systems that enables WSDs and mics to operate on the same TV channel with zero audible mic interference. SEISMIC implements a MicProtector to measure the interference at the mic receiver and a signaling protocol to notify the WSD of impending interference. This allows the WSD to optimize its transmission (e.g. through subcarrier suppression) without impacting mics. We motivate and describe SEISMIC and present a detailed performance analysis that shows that SEISMIC can regain up to 95% of the spectrum in single mic scenarios, and up to 85% in many (10+) mic environments.\",\n \"Title: A scalable peer-to-peer system for music content and information retrieval\\nYear: 2003\\n\\nAbstract: Currently a large percentage of Internet traffic con- sists of music files, typically stored in MP3 com- pressed audio format, shared and exchanged over Peer-to-Peer (P2P) networks. Searching for music is performed by specifying keywords and naive string matching techniques. In the past years the emerging research area of Music Information Retrieval (MIR) has produced a variety of new ways of looking at the problem of music search. Such MIR techniques can significantly enhance the ways user search for music over P2P networks. In order for that to happen there are two main challenges that need to be addressed: 1) scalability to large collections and number of peers, 2) richer set of search semantics that can support MIR especially when retrieval is content-based. In this paper, we describe a scalable P2P system that uses Rendezvous Points (RPs) for music metadata regis- tration and query resolution, that supports attribute- value search semantics as well as content-based re- trieval. The performance of the system has been eval- uated in large scale usage scenarios using \\\"real\\\" au- tomatically calculated musical content descriptors.\",\n \"Title: XIA: an architecture for an evolvable and trustworthy internet\\nYear: 2011\\n\\nAbstract: Motivated by limitations in today's host-based IP network architecture, recent studies have proposed clean-slate network architectures centered around alternative first-class principals, such as content, services, or users. However, much like the host-centric IP design, elevating one principal type above others hinders communication between other principals and inhibits the network's capability to evolve. Our work presents the eXpressive Internet Architecture (XIA), an architecture with native support for multiple principals and the ability to evolve its functionality to accommodate new, as yet unforeseen, principals over time. XIA also provides intrinsic security: communicating entities validate that their underlying intent was satisfied correctly without relying on external databases or configuration. In this paper, we focus on core architectural issues in the XIA data plane. We outline key design requirements relating to native support for multiple principals and intrinsic security. We then use case studies to demonstrate how the XIA design facilitates evolvability and flexibility.\",\n \"Title: Using emulation to understand and improve wireless networks and applications\\nYear: 2005\\n\\nAbstract: Researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we are developing a wireless emulator that enables both realistic and repeatable experimentation by leveraging physical layer emulation. We discuss the design and implementation of a prototype wireless emulator, and show how this emulator can be leveraged to provide insight into wireless network and application behaviour. Our experience shows that, compared to simulation, our emulator-based approach provides us with a better understanding of real-world wireless network performance, and enables us to quickly deploy our research into an operational wireless network, while still allowing us to enjoy the benefits of a controlled experimental environment.\",\n \"Title: Fpga-Based Channel Simulator For A Wireless Network Emulator\\nYear: 2009\\n\\nAbstract: Wireless channel emulators are important tools for testing radio devices, especially in mobile environments. Wireless network emulators give the same accuracy and control for testing radio network systems that traditional channel emulators give to point to point radio links. Network emulators require many more independent channels than traditional channel emulators. This problem is particularly challenging for the real time channel simulator in the emulator. The challenges of designing a wireless network channel simulator are discussed and a design is presented on a Xilinx Virtex-II Pro FPGA. This channel simulator can model 210 independent channels between 15 nodes with a bandwidth of 90MHz. The performance of the design was verified by measuring transport-layer throughput between 802.11b radios transmitting through the channel simulator.\",\n \"Title: A resource query interface for network-aware applications\\nYear: 1998\\n\\nAbstract: Networked systems provide a cost-effective platform for parallel computing, but the applications have to deal with the changing availability of computation and communication resources. Network-awareness is a recent attempt to bridge the gap between the realities of networks and the demands of applications. Network-aware applications obtain information about their execution environment and dynamically adapt to enhance their performance. Adaptation is especially important for synchronous parallel applications because a single busy communication link can become the bottleneck and degrade overall performance dramatically. This paper presents Remos, a uniform API that allows applications to obtain relevant network information, and reports on the development of parallel applications in this environment. The challenges in defining a uniform interface include network heterogeneity, diversity and variability in network traffic, and resource sharing in the network and even inside an application. The first implementation of the Remos interface uses SNMP to monitor IP-based networks. This paper reports on our methodology for developing adaptive parallel applications for high-speed networks with Remos and presents experimental results using applications generated by the Fx parallelizing compiler. The results highlight the importance and effectiveness of adaptive parallel computing.\",\n \"Title: An Architecture for the Integration of Physical and Informational Spaces\\nYear: 2002\\n\\nAbstract: While computer processing power, storage capacity, and bandwidth are continuing to experience exponential growth, individual human processing capabilities are not increasing significantly. Pervasive computing offers an opportunity for applications to interact with the physical environment and to provide a task-centric and mobile infrastructure for the user. However, this rich environment can also be distracting, in part because of a lack of convergence between the physical infrastructure observed by users and the information space seen by applications. In this paper we introduce AIPIS, an architecture that bridges the physical and informational realms of the human and the computer, respectively. The purpose of AIPIS is two-fold: (1) provide users with a hands-free computing environment that automates much of the drudgery associated with the use of computers; and (2) require human attention for only critical aspects of task execution that require their input. We also describe the Aura desktop, a first prototype of the AIPIS architecture.\",\n \"Title: A Hybrid Location Model with a Computable Location Identifier for Ubiquitous Computing\\nYear: 2002\\n\\nAbstract: Location modeling and representation are crucial technologies for context-aware applications. In this paper, we present a novel location model combining the virtues of both the hierarchical and coordinate location models, and we introduce a computable location identifier, namely Aura Location Identifier (ALI). We then describe how the Aura space service uses this hybrid model to handle spatial queries for contextaware applications. Asimple example of such a query is a range query, e.g. \\\"select name from printer where distance(location, 'ali://cmu/wean-hall/floor3/3100-corridor#(10,10,0)')\",\n \"Title: Undergraduate embedded system education at Carnegie Mellon\\nYear: 2005\\n\\nAbstract: Embedded systems encompass a wide range of applications, technologies, and disciplines, necessitating a broad approach to education. We describe embedded system coursework during the first 4 years of university education (the U.S. undergraduate level). Embedded application curriculum areas include: small and single-microcontroller applications, control systems, distributed embedded control, system-on-chip, networking, embedded PCs, critical systems, robotics, computer peripherals, wireless data systems, signal processing, and command and control. Additional cross-cutting skills that are important to embedded system designers include: security, dependability, energy-aware computing, software/systems engineering, real-time computing, and human--computer interaction. We describe lessons learned from teaching courses in many of these areas, as well as general skills taught and approaches used, including a heavy emphasis on course projects to teach system skills.\",\n \"Title: Pushing the envelope of indoor wireless spatial reuse using directional access points and clients\\nYear: 2010\\n\\nAbstract: Recent work demonstrates that directional antennas have significant potential to improve wireless network capacity in indoor environments. This paper provides a broader exploration of the design space of indoor directional antenna systems along two main dimensions: antenna configuration and antenna control. Studying a number of alternative configurations, we find that directionality on APs and clients can significantly improve performance, even over other configurations with stronger directionality. Moreover, it is sufficient to have a small number of narrow beam antennas to achieve such gains, thus making such a solution practical for actual deployment. Designing systems with directional APs and clients for increased spatial reuse comes, however, with a number of challenges in the way the directional antennas are controlled. Antenna control needs to encompass antenna orientation algorithms, an appropriate MAC layer protocol, and novel client-AP association solutions. To overcome these challenges, we propose Speed, a distributed directional antenna control system that is easy to deploy and significantly improves network capacity over existing solutions.\",\n \"Title: A software architecture for physical layer wireless network emulation\\nYear: 2006\\n\\nAbstract: Despite their widespread deployment, many aspects of wireless network performance are poorly understood, and there is great room from improvement in wireless network reliability and performance. A key obstacle to understanding and improving wireless networks has been the lack of a realistic yet flexible experimental methodology. Physical layer wireless network emulation promises to achieve much of the flexibility of wireless simulators while maintaining much of the realism of real wireless networks. We have developed a software architecture that tames the complexity of physical layer wireless network emulation, and presents users with a powerful yet ease-to-use interface. We present several case studies showing how this software architecture allows complex wireless experiments to be conducted in an efficient manner while still enabling novice users to quickly run simple experiments.\",\n \"Title: Efficient Support for Similarity Searches in DHT-Based Peer-to-Peer Systems\\nYear: 2007\\n\\nAbstract: Distributed hash tables (DHTs) provide a scalable and robust building block for content discovery in distributed applications such as Peer-to-Peer (P2P) systems. However, the basic DHT put/get API only supports simple exact queries. In this paper, we present a DHT-based system that efficiently supports similarity queries on multidimensional datasets. Our system embeds a logical kd-tree into the DHT's identifier space to form a distributed indexing structure, the distributed kd-tree (DKDT). We avoid creating bottlenecks, which are typical in tree- based systems, by relying on fully distributed protocols for tree management and data registrations and queries. We propose tree compressing and node shrinking techniques to efficiently support applications with high dimensionality datasets. Simulation results using both synthetic and real data show the effectiveness of our system.\",\n \"Title: Supporting the development of network programs\\nYear: 1991\\n\\nAbstract: Programmers who want to do network computing face several challenges: the network and attached systems are shared resources with an unpredictable behavior and network communication primitives are often hard to use. The programming environment developed for the Nectar system addresses both problems. It provides simple and efficient communication primitives, and an efficient monitoring kernel that allows both programmers and programming tools to monitor the behavior of the program in the dynamic network environment. Experience shows that monitoring the progress of applications interactively is both desirable and practical\",\n \"Title: Understanding link-level 802.11 behavior: replacing convention with measurement.\\nYear: 2007\\n\\nAbstract: Since wireless signals propagate through the ether, they are significantly affected by attenuation, fading, and interference. As a result, it is often difficult to measure and understand fundamental wireless network behavior. This creates a challenge for both network researchers, who often rely on simulators to evaluate their work, and network managers, who need to deploy and optimize operational networks. Given the complexity of wireless networks, both communities often rely on simplifying rules, which often have not been validated using today's wireless radios. In this paper, we undertake a detailed analysis of 802.11 link-level behavior using real hardware and a physical layer wireless network emulator that gives us complete control over signal propagation. We replace conventional assumptions and possible misconceptions with actual recorded behavior. Additionally, we analyze the impact of our observations on commonly deployed networks. Our work contributes to a more accurate understanding of link-level behavior and enables the development of more accurate wireless network simulators.\",\n \"Title: XIA: architecting a more trustworthy and evolvable internet\\nYear: 2014\\n\\nAbstract: Motivated by limitations in today's host-centric IP network, recent studies have proposed clean-slate network architectures centered around alternate first-class principals, such as content, services, or users. However, muchlike the host-centric IP design, elevating one principal type above others hinders communication between other principals and inhibits the network's capability to evolve. This paper presents the eXpressive Internet Architecture (XIA), an architecture with native support for multiple principals and the ability to evolve its functionality to accommodate new, as yet unforeseen, principals over time. We present the results of our ongoing research motivated by and building on the XIA architecture, ranging from topics at the physical level (``how fast can XIA go'') up through to the user level.\",\n \"Title: Simulating spatial cross-correlation in vehicular networks\\nYear: 2014\\n\\nAbstract: Wireless channels are defined by the presence and motion of objects between and around the communicating stations. As parts of the environment change, so do the channels between stations that are nearby. While the impact of environmental changes on individual channals has been studies extensively, the spatial autocorrelation across multiple channels, which we will call spatial cross-correlation, has received little attention. These effects are important whenever protocols use multiple channels in real time, such as in multi-hop networks. This paper studies the trade-offs between different ways of simulating spatial channel cross-correlation in the context of vehicular networks. We compare independent stochastic, locally cross-correlated stochastic, and explicitly geometric models in terms of both their complexity and the network-level performance they induce. Our results generally favor the geometric approach. Geometric models have higher precision and lower complexity than cross-correlated stochastic models, although collecting the detailed input needed for geometric models can be expensive. As a result, we propose a hybrid approach that combines geometric and stochastic approaches, depending on whether the impact of physical changes has a major or more minor impact on the channels.\",\n \"Title: The Cost of the \\\"S\\\" in HTTPS.\\nYear: 2014\\n\\nAbstract: Increased user concern over security and privacy on the Internet has led to widespread adoption of HTTPS, the secure version of HTTP. HTTPS authenticates the communicating end points and provides confidentiality for the ensuing communication. However, as with any security solution, it does not come for free. HTTPS may introduce overhead in terms of infrastructure costs, communication latency, data usage, and energy consumption. Moreover, given the opaqueness of the encrypted communication, any in-network value added services requiring visibility into application layer content, such as caches and virus scanners, become ineffective.\\n\\nThis paper attempts to shed some light on these costs. First, taking advantage of datasets collected from large ISPs, we examine the accelerating adoption of HTTPS over the last three years. Second, we quantify the direct and indirect costs of this evolution. Our results show that, indeed, security does not come for free. This work thus aims to stimulate discussion on technologies that can mitigate the costs of HTTPS while still protecting the user's privacy.\",\n \"Title: Balancing accountability and privacy in the network\\nYear: 2014\\n\\nAbstract: Though most would agree that accountability and privacy are both valuable, today's Internet provides little support for either. Previous efforts have explored ways to offer stronger guarantees for one of the two, typically at the expense of the other; indeed, at first glance accountability and privacy appear mutually exclusive. At the center of the tussle is the source address: in an accountable Internet, source addresses undeniably link packets and senders so hosts can be punished for bad behavior. In a privacy-preserving Internet, source addresses are hidden as much as possible. In this paper, we argue that a balance is possible. We introduce the Accountable and Private Internet Protocol (APIP), which splits source addresses into two separate fields --- an accountability address and a return address --- and introduces independent mechanisms for managing each. Accountability addresses, rather than pointing to hosts, point to accountability delegates, which agree to vouch for packets on their clients' behalves, taking appropriate action when misbehavior is reported. With accountability handled by delegates, senders are now free to mask their return addresses; we discuss a few techniques for doing so.\",\n \"Title: Using your smartphone to detect and map heterogeneous networks and devices in the home\\nYear: 2014\\n\\nAbstract: Heterogeneity in the wireless spectrum is an increasing problem which breaks down coordination and exacerbates wireless interference. In particular, this is a growing problem in the home: heterogeneity is increasing, yet there is a lack of tools and expertise in the home to gather the necessary information about its RF environment to combat this issue. In this paper, we present a unique monitoring system design which leverages the smartphone: now commodity, flexible and familiar to the home user, and equipped with multiple heterogeneous for sensing. Our design overcomes challenges inherent to monitoring with the phone (e.g., it is location agnostic without in-door localization) to derive where signals go and what they interfere with. It does so only requiring simple user-interaction, and as we will show, can bring the information to a level the user can understand.\",\n \"Title: Self-automated parking lots for autonomous vehicles based on vehicular ad hoc networking\\nYear: 2014\\n\\nAbstract: Parking is a major problem of car transportation, with important implications in traffic congestion and urban landscape. Reducing the space needed to park cars has led to the development of fully automated and mechanical parking systems. These systems are, however, limitedly deployed because of their construction and maintenance costs. Leveraging on semi and fully-autonomous vehicular technology, as well as on the electric propulsion paradigm and in vehicular ad hoc networking, we propose a new parking concept where the mobility of parked vehicles is managed by a parking lot controller to create space for cars entering or exiting the parking lot, in a collaborative manner. We show that the space needed to park such vehicles can be reduced to half the space needed with conventional parking lot designs. We also show that the total travelled distance of vehicles in this new parking lot paradigm can be 30% less than in conventional parking lots. Our proposal can have important consequences in parking costs and in urban landscape.\",\n \"Title: Centralized, measurement-based, spectrum management for environments with heterogeneous wireless networks\\nYear: 2014\\n\\nAbstract: Heterogeneity of wireless networks has become an increasing problem in the wireless spectrum that breaks down spectrum sharing and exacerbates interference. Many coexistence techniques have been proposed to alleviate this interference, however, they are difficult to deploy due to changes needed in the protocols, overhead, and rapid changes in technology. In this paper, we focus on the potential of spectrum management to provide a long-term solution. We introduce novel components to a spectrum management system that overcomes limitations of current models that have remained relatively focused on homogeneous environments. Our approach is a centralized one, where we analyze information collected from heterogeneous monitors available today, structure the information in a hypergraph, and perform an analysis to detect heterogeneous conflicts. Introducing a mixed integer program (in addition to other novel components), we reconfigure devices in the spectrum to avoid conflicts and improve performance.\",\n \"Title: A general architecture for load balancing in a distributed-memory environment\\nYear: 1993\\n\\nAbstract: The goal of load balancing is to assign to each node a number of tasks proportional to its performance. On distributed-memory machines, it is important to take data dependencies into account when distributing tasks, since they have a big impact on the communication requirements of the distributed application. The authors present a load balancing architecture that can deal with applications with heterogeneous tasks. The idea is to provide a set of load balancers that are effective for different types of homogeneous tasks, and to allow users to combine these load balancers for applications with heterogeneous tasks. This architecture was implemented on the Nectar multicomputer and performance results are presented for several applications with homogeneous and heterogeneous tasks\",\n \"Title: Data reshuffling in support of fast I/O for distributed-memory machines\\nYear: 1994\\n\\nAbstract: Achieving high-speed network I/O on distributed memory systems is a hard problem because their architectures are, in general, ill-suited for communication with the external world One of the problems is that messages are distributed over the private memories of the distributed memory system. This can result in poor performance since communication includes a complex scatter/gather operation. This paper presents a strategy in which the task of creating large contiguous messages is performed on the distributed-memory system, thus minimizing the overhead on the network interface. The performance results for an implementation of this strategy for an iWarp system with a HIPPI interface board are presented\",\n \"Title: Automatic generation of parallel programs with dynamic load balancing\\nYear: 1994\\n\\nAbstract: Existing parallelizing compilers are targeted towards parallel architectures where all processors are dedicated to a single application. However, a new type of parallel system has become available in the form of high perfor- mance workstations connected by high speed networks. Such systems pose new problems for compilers because the available processing power on each workstation may change with time due to other tasks competing for re- sources. We argue that it is possible for a parallelizing compiler to generate code that can dynamically shift por- tions of the application's workload between processors to improve performance. We have implemented a run-time system that supports automatically generated programs with dynamic load balancing. In this paper we describe this system and present performance measurements. We also describe the compiler functionality needed to gener- ate parallel programs with dynamic load balancing.\",\n \"Title: Copy emulation in checksummed, multiple-packet communication\\nYear: 1997\\n\\nAbstract: Data copying can be a bottleneck in end-to-end communication over high-speed networks. Emulated copy is an alternative I/O data passing scheme that preserves the API and integrity guarantees of copying but avoids the latter using virtual memory manipulations - transient output copy-on-write (TCOW), input alignment, and page swapping. We characterize and evaluate the support necessary in network adapters for emulated copy in checksummed, multiple-packet communication. Our experiments on an ATM network show that: (1) emulated copy gives performance better than that of copying even without hardware checksumming support; (2) TCOW improves multiple-packet output performance without any hardware support or changes in applications; (3) page swapping provides additional similar improvements on multiple-packet input if there is input alignment, which requires either hardware support (early-demultiplexed/system-aligned buffering) or changes in applications (pooled/application-aligned buffering); and (4) The performance of application-aligned buffering is largely unaffected by header/data splitting, a common optimization. We propose a new optimization, buffer snap-off, that extends system-aligned buffering to the general case of arbitrary, unmatched data transfer and application input buffer lengths\",\n \"Title: Experimental evaluation of ATM congestion control mechanisms\\nYear: 1997\\n\\nAbstract: A critical issue in the design of fast packet-switch-based networks is the avoidance of data loss due to congestion. In the context of ATM networks, many link-level congestion control mechanisms for ABR traffic have been proposed and simulated, and a few have been implemented. This paper presents, for the first time, an experimental comparison of several such mechanisms. To drive this comparison, we have developed a set of benchmarks that provide a quantitative characterization of congestion control performance. We also describe a simple but novel technique, the “virtual port card”, for implementing both non-native switch behavior and long link delays in ATM networks. This technique allows us to compare a wide range of mechanisms on a single flexible hardware platform. Our measurements show that while several of the ATM flow control mechanisms can eliminate cell loss, there are still several unresolved problems. First, for some traffic scenarios we see very poor application-level performance, especially in the presence of bursty traffic. Second, the performance is very sensitive to the flow control parameters and identifying an appropriate set of parameters is difficult since it depends heavily on the traffic conditions\",\n \"Title: Collecting network status information for network-aware applications\\nYear: 2000\\n\\nAbstract: Network-aware applications, i.e., applications that adapt to network con- ditions in an application specific way, need both static and d ynamic informa- tion about the network to be able to adapt intelligently to network conditions. The CMU Remos interface gives applications access to a wide range of in- formation in a network-independent fashion. Remos uses a logical topology to capture the network information that is relevant to applications in a con- cise way. However, collecting this information efficiently is challenging for several reasons: networks use diverse technologies and can be very large (Internet); applications need diverse information; and network managers might have concerns about leaking confidential information . In this paper we present an architecture for a hierarchical collector of network infor- mation. The decentralized architecture relies on data collectors that collect information on individual subnets; data collectors can collect information in manner that is appropriate for that subnet and can control the distribution of the information. For application queries that involve multiple subnets, we use a set of master collectors to partition requests and distribute subrequests to individual data collectors and to combines the results. Collectors cache recent network information to improve efficiency and respon siveness. This paper presents and justifies the collector architecture, de scribes a prototype implementation, and presents preliminary measurements characterizing its operation. Keywords—Network-aware applications, Network monitoring.\",\n \"Title: Effort-limited fair (ELF) scheduling for wireless networks\\nYear: 2000\\n\\nAbstract: While packet scheduling for wired links is a maturing area, scheduling of wireless links is less mature. A fundamental difference between wired and wireless links is that wireless media can exhibit substantial rates of link errors, resulting in significant and unpredictable loss of link capacity. This capacity loss results in a special challenge for wireless schedulers. For example, a Weighted Fair Queue (WFQ) scheduler assumes an error-free link and specifies how flows should share the link capacity. However, this specification is not sufficient to determine the correct outcome when link capacity is sharply reduced, because flows that have been allocated the same weights may differ greatly in their ability to tolerate throughput loss. In this paper, we first describe the wireless scheduling challenge in terms of an effort-outcome disconnection. Next we propose a novel notion of fair- ness for wireless links, effort-limited fairness(ELF), which extends WFQ via dynamic weight adjustments. ELF guarantees that all flows experiencing an error rate below a per-flow threshold receive their expected service, defined as a specified rate for reserved flows or a specified share of best-effort capac- ity for best-effort flows. After motivating and defining ELF, we present a practical approximation algorithm, which we evaluate through both trace- driven simulation and measurement of a prototype wireless radio network based on the WaveLAN physical layer. Keywords—Wireless networks, Quality of Service, Scheduling\",\n \"Title: Wireless Emulator Demonstration\\nYear: 2006\\n\\nAbstract: Researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we are developing a wireless emulator that enables both realistic and repeatable experimentation by leveraging physical layer emulation.\",\n \"Title: A stateless architectural approach to inter-domain QoS\\nYear: 2008\\n\\nAbstract: QoS provisioning as a generic telecom service is only useful if deployed end-to-end, so it must cover both the access segment and the interdomain segment of routes. This work focuses on the interdomain component of QoS architectures. Although the research community has been discussing several aspects of the problem, integrated architectures for true end-to-end QoS are still largely conceptual, especially if one considers mesh models and not simpler cascaded ones. Our inter-domain proposal combines offline service discovery and registration with real-time congestion notification, allowing us to significantly reduce the number of packets that were not suitably serviced, in the sense of fulfilling required Service Level Agreement constraints. We qualify our approach of dasiastatelesspsila since our proposal doesnpsilat use additional state in forwarding elements which is one of the most dramatic problems for interdomain scenarios.\",\n \"Title: Topological Implications of Cascading Interdomain Bilateral Traffic Agreements\\nYear: 2011\\n\\nAbstract: The Internet uses a model in which Autonomous Systems (AS) peer bilaterally with each other, resulting in a cascaded connectivity model: the end-to-end service that an end-user sees is the result of this cascade of bilateral traffic agreements. As a result, the routing decisions at each AS beyond the next hop are implicitly delegated, so an AS has limited control over the remaining path. While this may be considered a key feature of the Internet (e.g., helps scalability), the impact of this cascading model on the structure of the Internet is not yet well understood. In this paper, we analyze this cascaded model using concepts of game theory. Although our model cannot capture the full complexity of the real Internet - we actually aim at simplicity and try to only isolate the cascading effect -, our results suggest that cascading bilateral agreements brings order to an arbitrary graph. In particular, it brings forward some well-known properties of the Internet topology, such as the current AS hierarchy and common peering models. Finally, we compare our results with topological and routing data, obtained from CAIDA, looking for experimental evidence of our results, while further exploring the insight obtained from our model.\",\n \"Title: Inter-domain service alignment using consensus\\nYear: 2012\\n\\nAbstract: Despite its importance, end-to-end Quality-of-Service (QoS) is still an open problem mostly because of the inter-domain segment since for the access (end-user/operator) the problem has solutions for a diversity of commercially deployed architectures. The root problem lies in the coordination complexity: operators need to coordinate the traffic services they can offer, from service choice to cooperation models. We propose a framework that allows operators to agree on a useful set of services using machine-to-machine negotiation. This consensual service set dynamically balances users' demand, effort of deployment (like cost) and local business policies - ultimately obeying economics. By having the same set of services throughout the Internet, end-to-end QoS greatly reduces to an intra-domain QoS problem. We discuss the problem using a top-down approach: from formulating a multi-dimensional, iterative multi-objective optimization problem to a design proposal based on gossip protocols.\",\n \"Title: DAZL: Density-Aware Zone-based packet forwarding in vehicular networks\\nYear: 2012\\n\\nAbstract: Multi-hop message forwarding based on geographic coordinates is a fundamental building block for vehicular communication. However, the unstable links and wide range of node densities make it challenging to design an algorithm suitable for vehicular use. We introduce DAZL, a new forwarding protocol that combines three concepts in a novel way. First, multiple nodes cooperate in packet forwarding. Compared with traditional single relay schemes, this provides robustness against changes in topology and packet delivery rates. Second, network-layer slotting is used to control duplication and contention in high density scenarios. Third, a distributed prioritization algorithm is used to opportunistically maximize hop length. Through both experiments and simulations, we show that DAZL provides improvements of up to 60% in throughput over single relay forwarding, while ensuring low latency and replication.\",\n \"Title: Topology reconfiguration in Wi-Fi home networks\\nYear: 2013\\n\\nAbstract: The use of Wi-Fi is booming in home networks and it is making it harder for the technology to cope with this exponential growth. The high-bandwidth requirement of streaming services, data backups and interactive cloud applications require solutions to improve the performance of the network while simultaneously simplifying its management. This paper unveils a new Wi-Fi management paradigm relying on dynamic network topology reconfiguration that adjusts the network topology to its traffic matrix, and mitigates the performance pitfalls inherent to Wi-Fi and its fixed topology. A linear programming formulation relying on cross-layer information is provided to assess the potential gains of such solution, and an evaluation is performed that explores the achievable performance and range extension gains. The simulation results show a significant increase in the wireless network capacity - up to two fold - as well as improvements in the network range.\",\n \"Title: Multi-Context TLS (mcTLS): Enabling Secure In-Network Functionality in TLS.\\nYear: 2015\\n\\nAbstract: A significant fraction of Internet traffic is now encrypted and HTTPS will likely be the default in HTTP/2. However, Transport Layer Security (TLS), the standard protocol for encryption in the Internet, assumes that all functionality resides at the endpoints, making it impossible to use in-network services that optimize network resource usage, improve user experience, and protect clients and servers from security threats. Re-introducing in-network functionality into TLS sessions today is done through hacks, often weakening overall security. In this paper we introduce multi-context TLS (mcTLS), which extends TLS to support middleboxes. mcTLS breaks the current \\\\\\\"all-or-nothing\\\\\\\" security model by allowing endpoints and content providers to explicitly introduce middleboxes in secure end-to-end sessions while controlling which parts of the data they can read or write. We evaluate a prototype mcTLS implementation in both controlled and \\\\\\\"live\\\\\\\" experiments, showing that its benefits come at the cost of minimal overhead. More importantly, we show that mcTLS can be incrementally deployed and requires only small changes to client, server, and middlebox software.\",\n \"Title: Securing Passive Replication through Verification\\nYear: 2015\\n\\nAbstract: We show how to leverage trusted computing technology to design an efficient fully-passive replicated system tolerant to arbitrary failures. The system dramatically reduces the complexity of a fault-tolerant service, in terms of protocols, messages, data processing and non-deterministic operations. Our replication protocol enables the execution of a single protected service, replicating only its state, while allowing the backup replicas to check the correctness of the results. We implemented our protocol on Trusted Computing (TC) technology and compared it with two recent replication systems.\",\n \"Title: Do You Know Where Your Headers Are? Comparing the Privacy of Network Architectures with Share Count Analysis.\\nYear: 2015\\n\\nAbstract: Online privacy is more important now than ever. Using encryption goes a long way by hiding application data from third parties, but some amount of private information is still exposed in packet headers. Tools like Tor are designed to address this concern, and, more recently, research efforts to replace IP have begun to consider how a network architecture itself can improve privacy. Unfortunately, we do not have a good way to quantitatively compare network architectures (in terms of privacy and in general). We take the first steps in this direction by presenting share count analysis, a methodology for measuring \\\\\\\"how private\\\\\\\" an architecture is. We describe our design and implementation and present initial results indicating that this approach is promising.\",\n \"Title: Bootstrapping Evolvability for Inter-Domain Routing.\\nYear: 2015\\n\\nAbstract: It is extremely difficult to deploy newinter-domain routing protocols in today's Internet. As a result, the Internet's baseline protocol for connectivity, BGP, has remained largely unchanged, despite known significant flaws. The difficulty of deploying new protocols has also depressed opportunities for (currently commoditized) transit providers to provide value-added routing services. To help, we identify the key deployment models under which new protocols are introduced and the requirements each poses for enabling their usage goals. Based on these requirements, we argue for two modifications to BGP that will greatly improve support for new routing protocols.\",\n \"Title: Enabling Vehicular Applications using Cloud Services through Adaptive Computation Offloading\\nYear: 2015\\n\\nAbstract: There is growing interest in embedding new class of applications in vehicles to improve the user driving experience. However, the limited computational and storage resources in vehicles brings about a challenge of running computation and data intensive tasks of such applications in the vehicle's on-board unit (OBU). Moreover, embedded applications may not be easily updated by replacing hardware as upgrades in the vehicle OBUs can only happen over each vehicular life-cycle, which is of the order of 10-15 years. The advent of connectivity of vehicles to the Internet offers the possibility of offloading computation and data intensive tasks from the OBU to remote cloud servers for efficient execution. In this paper, we propose a novel architecture for bringing cloud-computing to vehicles where applications embedded in the vehicle OBU can benefit from remote execution of tasks provided as services in the cloud. We design a framework to identify and adaptively manage offloading of computation and data intensive tasks from the vehicle OBU to the cloud during application run-time. Through experimental evaluation using a preliminary prototype implementation of two computer vision applications that use our framework, we show that our approach can provide at least 3x reduction in the end-to-end application response time.\",\n \"Title: Lessons Learned From A Real Vehicular Network Deployment Of Delay-Tolerant Networking\\nYear: 2015\\n\\nAbstract: Vehicular networks are inherently unstable networks with high mobility and intermittent connectivity. These networks can greatly benefit from Delay Tolerant Networking (DTN) solutions for opportunistic connectivity in the transmission of delaytolerant data. In this paper, we evaluate the performance of different DTN routing protocols in real world vehicular networks with different degrees of connectivity in order to understand their feasibility in real vehicular environments.Our case-study application is the upload of delay-tolerant sensing data from vehicular nodes to a server on the Internet. We deploy DTN in 3 vehicular testbeds: a heterogeneous lab testbed with controlled mobility, a low-mobility high-connectivity network of harbor trucks, and a high-mobility low-connectivity city bus network. We compare 3 routing protocols: epidemic, static and PRoPHET, for which we measure delivery ratio, average delay, path length, as well as transmission and storage overhead. We analyze the results for experimental insight, and extract lessons for DTN routing protocol design.\",\n \"Title: Secure Identification of Actively Executed Code on a Generic Trusted Component\\nYear: 2016\\n\\nAbstract: Code identity is a fundamental concept for authenticated operations in Trusted Computing. In today's approach, the overhead of assigning an identity to a protected service increases linearly with the service code size. In addition, service code size continues to grow to accommodate richer services. This trend negatively impacts either the security or the efficiency of current protocols for trusted executions. We present an execution protocol that breaks the dependency between the code size of the service and the identification overhead, without affecting security, and that works on different trusted components. This is achieved by computing an identity for each of the code modules that are actually executed, and then building a robust chain of trust that links them together for efficient verification. We implemented and applied our protocol to a widely-deployed database engine, improving query-processing time up to 2× compared to the monolithic execution of the engine.\",\n \"Title: Identifying the root cause of video streaming issues on mobile devices.\\nYear: 2015\\n\\nAbstract: Video streaming on mobile devices is prone to a multitude of faults and although well established video Quality of Experience (QoE) metrics such as stall frequency are a good indicator of the problems perceived by the user, they do not provide any insights about the nature of the problem nor where it has occurred. Quantifying the correlation between the aforementioned faults and the users' experience is a challenging task due the large number of variables and the numerous points-of-failure. To address this problem, we developed a framework for diagnosing the root cause of mobile video QoE issues with the aid of machine learning. Our solution can take advantage of information collected at multiple vantage points between the video server and the mobile device to pinpoint the source of the problem. Moreover, our design works for different video types (e.g., bitrate, duration, ..) and contexts (e.g., wireless technology, encryption, ..) After training the system with a series of simulated faults in the lab, we analyzed the performance of each vantage point separately and when combined, in controlled and real world deployments. In both cases we find that the involved entities can independently detect QoE issues and that only a few vantage points are required to identify a problem's location and nature.\",\n \"Title: Demystifying and mitigating TCP stalls at the server side.\\nYear: 2015\\n\\nAbstract: TCP is an important factor affecting user-perceived performance of Internet applications. Diagnosing the causes behind TCP performance issues in the wild is essential for better understanding the current shortcomings in TCP. This paper presents a TCP flow performance analysis framework that classifies causes of TCP stalls. The framework forms the basis of a tool that is publicly available to the research community. We use our tool to analyze packet-level traces of three services (cloud storage, software download and web search) deployed by a popular Chinese service provider. We find that as many as 20% of the flows are stalled for half of their lifetime. Network-related causes, especially timeout retransmission, dominate the stalls. A breakdown of the causes for timeout retransmission stalls reveals that double retransmission and tail retransmission are among the top contributors. The importance of these causes depends however on the specific service. We also propose S-RTO, a mechanism that mitigates timeout retransmission stalls. S-RTO has been deployed on production front-end servers and results show that it is effective at improving TCP performance, especially for short flows.\",\n \"Title: An Empirical Analysis of a Large-scale Mobile Cloud Storage Service.\\nYear: 2016\\n\\nAbstract: Cloud storage services are serving a rapidly increasing number of mobile users. However, little is known about the differences between mobile and traditional cloud storage services at scale. In order to understand mobile user access behavior, we analyzed a dataset of 350 million HTTP request logs from a large-scale mobile cloud storage service. This paper presents our results and discusses the implications for system design and network performance. Our key observation is that the examined mobile cloud storage service is dominated by uploads, and the vast majority of users rarely retrieve their uploads during the one-week observation period. In other words, mobile users lean towards the usage of cloud storage for backup. This suggests that delta encoding and chunk-level deduplication found in traditional cloud storage services can be reasonably omitted in mobile scenarios. We also observed that the long idle time between chunk transmissions by Android clients should be shortened since they cause significant performance degradation due to the restart of TCP slow-start. Other observations related to session characteristics, load distribution, user behavior and engagement, and network performance.\",\n \"Title: Adaptive cloud offloading for vehicular applications\\nYear: 2016\\n\\nAbstract: The growing number of sensor-based interactive applications and services are pushing the limits of the on-board computing resources in vehicles. With vehicles increasingly being connected to the Internet, offloading the computation to cloud-computing infrastructures is an attractive solution. However, the large sensory data inputs of interactive applications makes offloading challenging across dynamic network conditions, and different application requirements or policies. To address this challenge, we design a system to adaptively offload specific vehicular application components or modules to the cloud. We particularly develop heuristic mechanisms for the placement and scheduling of modules on the On-Board Unit (OBU) and a cloud server under dynamic networking conditions during driving. Through an experimental evaluation of the end-end application response time using our prototype vehicular cloud offloading system, we show that our mechanism can help meet application response time constraints.\",\n \"Title: Bootstrapping evolvability for inter-domain routing with D-BGP\\nYear: 2017\\n\\nAbstract: The Internet's inter-domain routing infrastructure, provided today by BGP, is extremely rigid and does not facilitate the introduction of new inter-domain routing protocols. This rigidity has made it incredibly difficult to widely deploy critical fixes to BGP. It has also depressed ASes' ability to sell value-added services or replace BGP entirely with a more sophisticated protocol. Even if operators undertook the significant effort needed to fix or replace BGP, it is likely the next protocol will be just as difficult to change or evolve. To help, this paper identifies two features needed in the routing infrastructure (i.e., within any inter-domain routing protocol) to facilitate evolution to new protocols. To understand their utility, it presents D-BGP, a version of BGP that incorporates them.\",\n \"Title: Secure Tera-scale Data Crunching with a Small TCB\\nYear: 2017\\n\\nAbstract: Outsourcing services to third-party providers comes with a high security cost-to fully trust the providers. Using trusted hardware can help, but current trusted execution environments do not adequately support services that process very large scale datasets. We present LAST\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">GT</sup>\\n, a system that bridges this gap by supporting the execution of self-contained services over a large state, with a small and generic trusted computing base (TCB). LAST\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">GT</sup>\\n uses widely deployed trusted hardware to guarantee integrity and verifiability of the execution on a remote platform, and it securely supplies data to the service through simple techniques based on virtual memory. As a result, LAST\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">GT</sup>\\n is general and applicable to many scenarios such as computational genomics and databases, as we show in our experimental evaluation based on an implementation of LAST-GT on a secure hypervisor. We also describe a possible implementation on Intel SGX.\",\n \"Title: Vehicular Cloud Computing through Dynamic Computation Offloading.\\nYear: 2018\\n\\nAbstract: The growing demand in the number of sensor–dependent applications and infotainment services in vehicles is pushing the limits of their on–board computing resources. Today, vehicles are increasingly being connected to the Internet and becoming a part of the Smart Internet–of–Things (IoT) paradigm. Leveraging such connectivity, the idea of vehicular cloud–computing, where computation for vehicular applications and services are offloaded to the cloud, becomes an attractive proposition. However, the large sensory data inputs, strict latency requirements, and dynamic wireless networking conditions make offloading of vehicular applications to the cloud very challenging. To address this challenge, we design a dynamic approach for offloading specific vehicular application components or modules. We develop heuristic mechanisms for placement and scheduling of these modules in the on–board unit versus the cloud. The highlight of the proposed design is the ability to offload computation to the cloud in an elastic manner through dynamic decisions during variable network conditions. Through an experimental evaluation using our prototype system we show the effectiveness of the design in reducing the response time for compute intensive applications across variable network conditions in two urban environments.\",\n \"Title: TCP Stalls at the Server Side: Measurement and Mitigation\\nYear: 2019\\n\\nAbstract: TCP is an important factor affecting user-perceived performance of Internet applications. Diagnosing the causes behind TCP performance issues in the wild is essential for better understanding the current shortcomings in TCP. This paper presents a TCP flow performance analysis framework that classifies causes of TCP stalls. The framework forms the basis of a tool that we use to analyze packet-level traces of three services (cloud storage, software download, and web search) deployed by a popular service provider. We find that as many as 20% of the flows are stalled for half of their lifetime. Network-related causes, especially timeout retransmissions, dominate the stalls. A breakdown of the causes for timeout retransmission stalls reveals that double retransmission and tail retransmission are among the top contributors. The importance of these causes depends however on the specific service. Based on these observations, we propose smart-retransmission time out (S-RTO), a mechanism that mitigates timeout retransmission stalls through careful and gentle aggression for retransmission. S-RTO is evaluated in a controlled network and also in a production network. The results consistently show that it is effective at improving TCP performance, especially for short flows.\",\n \"Title: And Then There Were More: Secure Communication for More Than Two Parties.\\nYear: 2017\\n\\nAbstract: Internet communication today typically involves intermediary middleboxes like caches, compression proxies, or virus scanners. Unfortunately, as encryption becomes more widespread, these middleboxes become blind and we lose their security, functionality, and performance benefits. Despite initial efforts in both industry and academia, we remain unsure how to integrate middleboxes into secure sessions---it is not even clear how to define \\\"secure\\\" in this multi-entity context.\\n\\nIn this paper, we first describe a design space for secure multi-entity communication protocols, highlighting tradeoffs between mutually incompatible properties. We then target real-world requirements unmet by existing protocols, like outsourcing middleboxes to untrusted infrastructure and supporting legacy clients. We propose a security definition and present Middlebox TLS (mbTLS), a protocol that provides it (in part by using Intel SGX to protect middleboxes from untrusted hardware). We show that mbTLS is deployable today and introduces little overhead, and we describe our experience building a simple mbTLS HTTP proxy.\",\n \"Title: Second-Order Destination Inference using Semi-Supervised Self-Training for Entry-Only Passenger Data.\\nYear: 2017\\n\\nAbstract: Automated data collection in urban transportation systems produces a large volume of passenger data. However, quite a few of the data are still incomplete, limiting the insight into passenger mobility. The unavailability of destination information in entry-only passenger data is a very common issue. Traditional approaches for estimating passenger destinations rely on heuristics that can recover only some of the missing destinations. To deal with the remaining incomplete data, this paper, for the first time, proposes a second-order inference methodology to leverage semi-supervised self-training to infer the missing destinations. The methodology involves the design of a base learner to predict the missing destinations based on the statistics of a selected similarity-based set, and the design of a selection strategy to select new data with high prediction confidence to update the training set. To further improve the inference, we incorporate personal history priors to modify the base learner. We evaluate our designs using two data sources: a real-data inspired traffic-passenger behavior simulation in the city of Porto, Portugal, and the real bus Automated Fare Collection (AFC) data collected from the same city. The experimental results show that compared to baseline methods that do not use self-training, our approach significantly improves the inference performance and achieves notably high accuracies.\",\n \"Title: Analysis and improvement of name-based packet forwarding over flat ID network architectures\\nYear: 2018\\n\\nAbstract: One of ICN's main challenges is attaining forwarding table scalability when confronted with a huge content space. This is specially true in flat ID architectures, which do not naturally support route aggregation for hierarchical names. Previous work has proposed improving scalability by aggregating content names in a fixed-size Bloom Filters (BF). However, the negative impact of false positive (FPs) matches on forwarding correctness and performance has not been studied thoroughly. In this paper, we study the end-to-end network performance of BF-based forwarding. We devise an analytical model that accurately models BF-based forwarding and the flow of BF-based packets over inter-domain topologies. Using this model, we show that the use of BFs for packet forwarding puts feasibility at odds with scalability. Based on our analysis, we propose and evaluate several strategies to improve the feasibility of BF-based forwarding and examine different scenarios for which BF-based forwarding is suitable.\",\n \"Title: PARI: A Probabilistic Approach to AS Relationships Inference.\\nYear: 2019\\n\\nAbstract: Over the last two decades, several algorithms have been proposed to infer the type of relationship between Autonomous Systems (ASes). While the recent works have achieved increasingly higher accuracy, there has not been a systematic study on the uncertainty of AS relationship inference. In this paper, we analyze the factors contributing to this uncertainty and introduce a new paradigm to explicitly model the uncertainty and reflect it in the inference result. We also present PARI, an exemplary algorithm implementing this paradigm, that leverages a novel technique to capture the interdependence of relationship inference across AS links.\",\n \"Title: Telemetry Retrieval Inaccuracy in Programmable Switches: Analysis and Recommendations\\nYear: 2021\\n\\nAbstract: ABSTRACTSketching algorithms or sketches are attractive as telemetry capabilities on programmable hardware switches since they offer rigorous accuracy guarantees and use compact data structures. However, we find that in practice, their actual implementations can have a significant (up to 94×) accuracy drop compared to theoretical expectations. We find that the delays incurred by pulling and resetting the data plane state induce accuracy degradation. We design and implement solutions to reduce the delays and show that our solutions can help eliminate almost all the inaccuracy of existing sketch workflows.\",\n \"Title: Meeting connected vehicle application requirements: it's not just about bandwidth\\nYear: 2021\\n\\nAbstract: BSTRACTThe growing popularity of connected vehicles is driving the development of a new class of latency-sensitive applications. The applications can benefit from edge clouds but they need timely responses to their requests. For applications based on video and other sensor data, this necessitates high burst throughput from the network, which results in a challenging scheduling problem since applications have diverse request sizes, rates, and deadlines. While the problem of managing latency sensitive bursty traffic has been considered in data centers, wireless networks use variable bit rates, which further exacerbates the problem. In this paper, we first use simple examples to show that traditional network fairness and quality-of-service (QoS) solutions are not appropriate for latency sensitive applications using cloud services at the wireless edge. We then sketch a possible solution that addresses the challenges of combining Service Level Agreements that focus on burst transfers with a network scheduler that is resource-aware. Finally, we use a simplified network, namely Wi-Fi based emulation, to show how our approach enables both the network administrator and applications to meet their goals.\",\n \"Title: Time-division TCP for reconfigurable data center networks\\nYear: 2022\\n\\nAbstract: Recent proposals for reconfigurable data center networks have shown that providing multiple time-varying paths can improve network capacity and lower physical latency. However, existing TCP variants are ill-suited to utilize available capacity because their congestion control cannot react quickly enough to drastic variations in bandwidth and latency. We present Time-division TCP (TDTCP), a new TCP variant designed for reconfigurable data center networks. TDTCP recognizes that communication in these fabrics happens over a set of paths, each having its own physical characteristics and cross traffic. TDTCP multiplexes each connection across multiple independent congestion states---one for each distinct path---while managing connection-wide tasks in a shared fashion. It leverages network support to receive timely notification of path changes and promptly matches its local view to the current path. We implement TDTCP in the Linux kernel. Results on an emulated network show that TDTCP improves throughput over both traditional TCP variants, such as DCTCP and CUBIC, and multipath TCP by 24--41% without requiring significant in-network buffering to hide path variations.\",\n \"Title: Time-Sensitive Cooperative Perception for Real-Time Data Sharing over Vehicular Communications: Overview, Challenges, and Future Directions\\nYear: 2022\\n\\nAbstract: Cooperative perception is a prospective application to improve road safety by having connected autonomous vehicles (CAVs) exchange their raw or processed sensor data over vehicular communications. Since CAVs heavily rely on sensor-based perception, including vision cameras, LiDARs, and radars, cooperative perception has an immense potential to improve road safety. At the same time, a variety of sensors and edge servers have been widely deployed in smart cities, and such sensors and servers might be able to empower CAVs on public roads. In this article, we comprehensively study such cooperative perception for overview, technical challenges, practical requirements, prospective system designs, current approaches, and future research directions. In particular, we focus on the time sensitivity of the cooperative perception frameworks, in which delays of computing and communications lead to detection errors. In addition, we comprehensively study sensor fusion frameworks and models to improve the detection accuracy and reliability of CAVs while avoiding information flooding and/or rumor spreading. Since network congestion might lead to packet collisions and/or delays, congestion control might be essential to use cooperative perception in practice. Finally, we discuss the technical and ethical challenges of using cooperative perception on public roads and conclude with future research directions.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":151,"string":"151"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":270,"string":"270"}}},{"rowIdx":271,"cells":{"question_id":{"kind":"string","value":"Fusako Kusunoki"},"question":{"kind":"string","value":"Generate an abstract for the title \"SoundSpot: a next-generation audio-guide system for museums\" using the following items: 1. SoundSpot\n2. Audio-guide \n3. Museums\n4. Children\n5. Effectiveness"},"answer":{"kind":"string","value":"In this paper, we propose a system called SoundSpot, which is A Next-generation Audio-guide System for museums. Although the original goal of the system is to solve problems in audio-based annotations, the system can attract a lot of interest as an magical entertainment system. So though the system we aim that children can enhance their motivation to know information which are related to exhibitions. We evaluated the system in a Japanese science museum and confirmed its effectiveness."},"correct_answer":{"kind":"string","value":"In this paper, we propose a system called SoundSpot, which is A Next-generation Audio-guide System for museums. Although the original goal of the system is to solve problems in audio-based annotations, the system can attract a lot of interest as an magical entertainment system. So though the system we aim that children can enhance their motivation to know information which are related to exhibitions. We evaluated the system in a Japanese science museum and confirmed its effectiveness."},"documents":{"kind":"list like","value":["Title: KOTOHIRAGU NAVIGATOR: an open experiment of location-aware service for popular mobile phones\nYear: 2006\n\nAbstract: We have developed a location-aware sightseeing support system for visitors to KOTOHIRAGU Shrine, using only popular mobile phones employing the gpsOne system. Its design is not a map-based navigation system, but a shared virtual world system like multi-player online role-playing games. We conducted an experiment recruiting 29 subjects from real tourists visiting the shrine, who had their own compatible GPS-phones. From the survey, we have found that location-aware sightseeing support system using mobile phones can be accepted by young people, but the generation gap is wider than expected.","Title: To use PYA tool or not for learning Japanese hand alphabets\nYear: 2006\n\nAbstract: We are developing an easy-to-use edutainment system: Practice! YUBIMOJI AIUEO (PYA). The objective is to promote basic expressions of Kana characters (AIUEO) of Japanese hand alphabets (YUBIMOJI) to ordinary children at elementary school age. PYA seems to work well from users' behaviors and responses, however, the effectiveness has not been fully confirmed, so far. In this paper, we have carried out series of intensive experiments at classrooms of Sumiyoshi Elementary School (7 or 8 years old; 83 subjects). The results are summarized as follows: 1) Devices the children use to learn do not affect the performance just after the study; 2) the PC use is effective when the target characters are complex and similar; and 3) The PC users keep remembering difficult shapes of characters after one month. These results have suggested that the use of PCs is superior to the ordinary oral lectures, however, it depends on the features of characters.","Title: What you look like when learning hand alphabets\nYear: 2005\n\nAbstract: When ordinary people learn hand languages, it is critical to properly understand that the forms of the hand shapes and moves are different for speakers and listeners. To cope with the issue, we have equipped a PC camera with the visual interface of an edutainment system for Japanese hand alphabets. To investigate the visual interface, we have conducted experiments with/without the camera device to measure the eye movement when subjects use the interface The experimental results have shown the effectiveness of the how-you-look-smart interface with a PC camera.","Title: Design and evaluation of a virtual mobile time machine in education\nYear: 2008\n\nAbstract: We have developed a \"virtual time machine\" for edutainment, which needs only commercially available mobile phones. In reality, the system just shows graphical images of a past scene within a given area, viewing from the location given by GPS and with arbitrary viewing angles. Users can virtually explore the past world with it. We applied it to junior high school students. They virtually visited a world of 1938, when a landslide disaster occurred. They were able to directly compare now and the past. In this paper, the design approach and evaluation of our edutainment practice are given. Our system raised students' motivations.","Title: Design of an interactive system for group learning support\nYear: 2002\n\nAbstract: In this paper we describe our project to design a system that can be used as a teaching aid to support group learning in elementary school education. The system enhances the learning outcome for pupils who have studied environmental problems using a textbook, by allowing them to construct a town in a physical space and to assess the construction through computer simulations. The system was designed in collaboration with teachers and their pupils in elementary schools. Lessons learned from the collaborative design processes are described.","Title: A Laser Show Device Works in an Open Space for Hearing-Impaired Students\nYear: 2008\n\nAbstract: The paper proposes a new pointing device for education of hearing-impaired students. The device: Big Fat Wand (BFW) is developed from a conventional laser show device, however, is modified to a small enough one to be used at out-of classroom lectures. BFW is connected to a laptop PC, which provides character, symbol images, and/or animations with the device through a conventional one board microcomputer. This paper describes the educational objectives, basic principles, and preliminary experimental results of BFW. We conclude that BFW is a good gear to improve the methodology to educate and educate hearing-impaired students.","Title: Letting every pupil learn Japanese hand alphabets with VIUAL interfaces\nYear: 2004\n\nAbstract: This paper discusses the effects of a visual interface for the Japanese hand language system. The system Practice! Yubimoji AIUEO (PYA) we are developing aims at letting ordinary pupils learn basic character expressions (AIUEO) of the Japanese hand characters (Yubimoji). Because very few pupils in Japan are currently able to communicate with handicapped people and there are only complex, expensive, and difficult software systems and/or textbooks available to learn the language system, it is critical to deliver easy-to-use software systems on a PC at elementary schools. This paper describes what are the principles of PYA, how PYA works, and why PYA is effective from pedagogical and computer human interaction points of view.","Title: A system for supporting collaborative learning with networked sensing boards\nYear: 2004\n\nAbstract: The authors have used sensing boards based on RFID technology to construct a face-to-face group learning support system integrating the physical world and the virtual world. The system is shown to be useful through performance in that a learner without sufficient skill in using a computer can easily participate in learning, and knowledge acquired through textbooks and the like can be tested in the physical world. On the other hand, some problems have been pointed out: the utterances depend more strongly on the leader, and learning support with a higher degree of realism is desired. Consequently, in the system proposed in this paper, multiple sensing boards are placed at different sites so that the learner groups can communicate face-to-face. The sensing boards are connected through a network so that the operations on the board can influence each other. The learners in the group gather around the board and try to solve the problem face-to-face. They also interact with the learners in another group through a chat system. The learners in a primary school classroom used the system to study city design and environmental problems, and the effectiveness of the proposed system was demonstrated. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(9): 39–50, 2004; Published online in Wiley InterScience (). DOI 10.1002/scj.10502","Title: LEGS system in a zoo: use of mobile phones to enhance observation of animals\nYear: 2009\n\nAbstract: In the LEGS system, GPS-equipped mobile phones are used to learn about animals and their bodies from the viewpoint of evolution in a zoo. This system identifies nearby animals, asks questions about the animals' bodies to enhance observation, provides navigations for the next observations, and summarizes several observed animals' parts from the viewpoint of evolution. 24 students (age: 14--15 years old) learnt about animals using the mobile phones in a zoo. We evaluated the system and found that it helped students explore, observe, and learn about animals' bodies independently in the zoo.","Title: KEI-time traveler: visiting a past world with mobile phones to enhance learning motivation\nYear: 2008\n\nAbstract: KEI-Time Traveler is a system using commercially available phones equipped with GPS. It enables students to do fieldwork with a visit to a past environment from the corresponding location in the present world. Students experienced such fieldwork to visit the site of a landslide disaster in 1938. We evaluated the system and found that KEI-Time Traveler enhanced motivation and helped students learn about their local area's history.","Title: Multi-Audible table for collaborative work\nYear: 2004\n\nAbstract: This paper presents a prototype Multi-Audible system. By Multi-Audible, we mean that plural users have a portable device to hear different audio information during the interaction. The proposed system is an interactive art system that sends auditory information to a user through the device based on the position of that user's finger on a table with touch screen functionality. We describe the hardware and software configuration, contents of the proposed system, and some midterm experimental results.","Title: Symphony-Q: a support system for learning music through collaboration\nYear: 2002\n\nAbstract: This paper describes the Symphony-Q support system for learning music. This system integrates a sensing board and a computer, and is used for collaborative learning in a face-to-face setting. One of the aims of Symphony-Q is to enhance music experiences: children who do not have music skills can easily participate in music learning, enjoy making sounds, and play rhythmically to music in collaboration with others. The paper discusses comments and feedback from school children and their teachers, which were collected during experiments with Symphony-Q carried out in a Japanese public elementary school.","Title: Development and Evaluation of a Digital Vegetation Interaction Game for Children\nYear: 2009\n\nAbstract: In this study, we develop a new digital sugoroku game that portray the phenomenon of vegetation succession in a forest. The results of the experimental evaluation showed that the game was effective in stimulating the interest of the students who participated in the game.","Title: Learning by Doing: Space-Associate Language Learning Using a Sensorized Environment\nYear: 2005\n\nAbstract: This paper proposes a Learning-by-Doing (LBD) system for assisting learners of English as a foreign language, by providing educational content generated based on real-world behaviors in a sensorized environment. The LBD system consists of an ultrasonic location sensing system developed by the authors and an educational content server. The location of the student is monitored by ultrasonic sensors embedded around the learning room. The system voices English verbs related to objects around the student so that the student can obtain the language skills for expressing various activities of everyday life in English by performing real-world behaviors. The system was implemented experimentally in an English language school. Six subjects participated in an experiment evaluating the educational efficacy of the proposed system. Recall rates of learned verbs were compared among three methodologies, \"Learning by text,\" \"Learning by pictures and text,\" and \"Learning by doing\". Recall rates were measured at the following intervals: soon after the learning task, 2 days after, 4 days after, 7 days after, and 14 days after the learning task. The results indicate that the proposed LBD system increased the recall rate of learned words by 113% 14 days after the learning task. Overall, the system significantly increased the average recall rate by 102% in comparison to the other learning methodologies.","Title: The preliminary study of animation dictionary for onomatopoeic learning\nYear: 2007\n\nAbstract: In this paper we discuss the effectiveness of animation dictionaries. We focus on a design solution to Japanese onomatopoeic accessibility problems for the children who are hearing-impaired. Our approach is to design educational materials for deaf or hard-of-hearing children at the learning of the onomatopoeic expressions, to make the best of their abilities rather than compensating for their disabilities. Our preliminary investigation suggests that the onomatopoeic expressions accompanied by animation would be able to transmit emotional images of words. The animations were more effective than text or video clips. We believe that an animation dictionary would be an effective educational material that is understandable by hearing-impaired children.","Title: Experiments of entertainment applications of a virtual world system for mobile phones\nYear: 2005\n\nAbstract: Using a virtual world system for GPS-phones, we have developed a small RPG-like game to give information to tourists. Comparing with other virtual systems for mobile terminals, the cost of our system is much lower because only phones on the current market are required but no additional devices are needed. The game follows a Japanese famous tale and a player plays as the hero. We recruited twenty subjects and they played it 35 minutes in average. Through evaluation sessions of the system, we have found that the system is highly evaluated as an entertainment system.","Title: Vegetation interaction game: digital SUGOROKU of vegetation succession for children\nYear: 2010\n\nAbstract: In this study, we redesign and develop a new digital sugoroku game based on the phenomenon of vegetation succession. A practical evaluation in an elementary school that consisted of game play and fieldwork activity was conducted. The results of the evaluation showed that the game was effective in stimulating the interest of the students who participated in the game, and was able to support their learning in a joyful way.","Title: Interactive and enjoyable interface in museum\nYear: 2005\n\nAbstract: Exhibitions at a scientific museum are usually difficult for ordinary school pupils. To improve the issues of current explanation systems, we use Personal Data Assistant (PDA) devices. Recent PDAs have enough functionality for people to interactively, individually, but it is not easy to assist that school pupils learn scientific knowledge merely using PDA.This research examined the main focus of the design and implementation of visual interfaces for PDAs for such a learning system. We aims the visual interface for PDAs have more interactive and entertainment to engage for learning scientific knowledge. Experiments using two prototype systems(Pi-book and Pit A Pat)implemented in the Flash/MX software toolkit have suggested the effectiveness on the performance and functionality of the proposed method.","Title: Learning onomatopoeic expressions by animation\nYear: 2007\n\nAbstract: This paper focuses on a design solution to Japanese onomatopoeic accessibility problems for the hard-of-hearing. Our research suggests that the onomatopoeic expressions accompanied by animation would be able to transmit emotional images of words. The animations were more effective than text or video clips. We believe that an animation dictionary would be an effective educational material that is understandable by hard-of-hearing students.","Title: A Handy Laser Show System for Open Space Entertainment\nYear: 2009\n\nAbstract: Big Fat Wand (BFW) is a handy laser show system, which includes a portable laser show device newly developed and a laptop PC with easy-to-use authoring toolkits. This paper describes basic principles and architecture of BFW, then demonstrates how BFW is used in an open space environment.","Title: Making a Hands-On Display with Augmented Reality Work at a Science Museum\nYear: 2013\n\nAbstract: In this paper, we propose an augmented reality (AR) system with a laser projection device as a hands-on display at a science museum. The AR system provides virtual information, which learners can control for a visual explanation about an exhibited item. Learners develop their knowledge and understanding through the display without any modification to the item and/or the existing displayed explanation. We conducted an experiment using the AR system, with child visitors to Gamagori Museum of Earth, Life and the Sea. AR systems should meet the following criteria if they are to be considered effective: i) the display should make learners interested in the exhibited item, ii) learners should be able to easily handle the AR display, and iii) learners should construct their knowledge through using the display. In our experiment, we evaluated the AR display against these criteria. We conclude that the AR display system enables learners to construct their knowledge in reality, and that the system encourages learners' interest in the exhibited items.","Title: Electronically enhanced board games by integrating physical and virtual spaces\nYear: 2002\n\nAbstract: This paper describes an electronically enhanced board called E 2board. The motivation of our work comes from a traditional board game, which groups of players enjoy in a face-to-face situation by manipulating pieces on a physical board. In order to enhance users’ excitement and immersiveness, a physical board and a virtual world created by a computer are linked together with E 2board. An important function of E 2board is the rapid recognition of massive numbers of different objects. The authors have developed several applications using E 2board: not only games, but also systems for supporting group activities. Some of these applications are shown.","Title: Edutaining school pupils for Japanese hand alphabets\nYear: 2004\n\nAbstract: This paper presents Practice! Yubimoji AIUEO (PYA) to let ordinary elementary school pupils learn basic character expressions (AIUEO) of the Japanese hand characters (Yubimoji). PYA at a Personal Computer has an easy-to-use and look-and-feel visual interfaces. This paper describes what are the principles of PYA, how PYA works, and why PYA is effective from the edutainment view.","Title: CarettaKids: a system for supporting children's face-to-face collaborative learning by integrating personal and shared spaces.\nYear: 2006\n\nAbstract: We developed a new system called CarettaKids that supports face-to-face collaborative learning by children. CarettaKids uses a sensing board based on the Radio Frequency Identification (RFID) technology to support collaboration in a shared space, and the Personal Digital Assistant (PDA) device to support activity in personal spaces. We also introduced this system into an actual classroom environment to evaluate its performance in support for children's collaborative learning, by analyzing the childrens' interaction. As a result, we have confirmed that CarettaKids's feature of transition between two spaces, makes it possible for children to reflect on problems detected in the shared space so as to find solutions in their respective personal space, and to engage in an active exchange of opinions in the shared space, based on ideas generated from personal-space learning.","Title: Development of a Full-Body Interaction Digital Game for Children to Learn Vegetation Succession\nYear: 2013\n\nAbstract: In this study, we developed a simulation game called \\\"Human SUGOROKU\\\" that simulates vegetation succession of the real forest area in the virtual world. This game consists of a full-body interaction system to enable children to enjoy and learn vegetation succession by playing with their body movement. We conducted an experiment with children and investigated the effects of the full-body interaction through interviews. The results showed that the full-body interaction promotes a sense of immersion in the game. This paper describes the structure of this system and the interview results.","Title: Fostering students' participation in face-to-face interactions and deepening their understanding by integrating personal and shared spaces\nYear: 2007\n\nAbstract: In this research, we introduced CarettaKids into the social context of a classroom environment to evaluate whether integration of personal and shared spaces can help promote students' participation in synchronous/co-located interactions in the classroom and deepen their understanding of subject matter. Analysis of videotaped interactions and pre-and posttests clarified the following three points. (1) Students who used CarettaKids presented the simulation results and rules for object arrangement they worked out individually in their respective personal space, by using CarettaKids' function of projecting object arrangements and simulation results from a personal digital assistant onto a sensing board. (2) Many of the students who used CarettaKids examined individually generated ideas collaboratively in the shared space. The patterns of collaborative examination are: (a) Induce a rule for object arrangement from object arrangements devised in personal spaces; (b) Deduce a new object arrangement from the rules discovered in the personal spaces; and (c) Refine the rules discovered in the personal spaces through group discussion. (3) Students who used CarettaKids not only considered all of the three factors, i.e. residential area, industrial area and forest area, but also understood relations between these factors, thereby deepening their understanding of city planning that takes environmental and financial aspects into consideration. We suggest that the degree to which students deepen their understanding is affected by the presence or absence of collaborative examination of individually generated ideas in the shared space.","Title: Design and Evaluation of a Location-Based Virtual City System for Mobile Phones\nYear: 2005\n\nAbstract: We are developing a virtual city system with a model that consists of virtual architectural objects and virtual creatures, geographically overlaid onto the real world. People who have mobile terminals with location sensors like GPS can visit the virtual city when walking about in a real city. The most important aspect of our research is that we have adopted current market mobile phones. In this paper we describe a prototype of virtual city system and its evaluation. The result of evaluation suggests that subjects were very much interested in the virtual city system. Technical problems have been revealed by the evaluation but most of them will be solved or minimized if we use the next generation of mobile phones.","Title: Open experiments of mobile sightseeing support systems with shared virtual worlds\nYear: 2006\n\nAbstract: In this paper, we describe results from the experiments of a location-dependent shared virtual world system applied to sightseeing entertainment. This system can be used with GPS-phones on the current Japanese market. Users can enjoy interacting with virtual objects including virtual animals/agents. Subjects of the experiments were real tourists who had their own GPS-phones compatible with our system. We found that evaluations on the system varied depending on age, gender, and experiences of subjects. Results from the experiments gave suggestions on prospective users and service design.","Title: Human SUGOROKU: learning support system of vegetation succession with full-body interaction interface\nYear: 2014\n\nAbstract: In this study, we developed a simulation game called \"Human SUGOROKU\" that consists of a full-body interaction system to enable elementary school students to enjoy and learn vegetation succession. The students' sense of immersion is improved by enabling them to play this game using their body movements. We conducted an experiment with the students and investigated the affects of the full-body interaction through questionnaires. The results showed that the full-body interaction promotes a sense of immersion in the game and enhance their understanding of vegetation succession. This paper describes the structure of this system and the questionnaires results.","Title: Human SUGOROKU: full-body interaction system for students to learn vegetation succession\nYear: 2013\n\nAbstract: In this study, we developed a simulation game called \"Human SUGOROKU\" that consists of a full-body interaction system to enable elementary school students to enjoy and learn vegetation succession. The students' sense of immersion is improved by enabling them to play this game using their body movements. We conducted an experiment with the students and investigated the affects of the full-body interaction through interviews. The results showed that the full-body interaction promotes a sense of immersion in the game. This paper describes the structure of this system and the interview results.","Title: Musex: A System for Supporting Children's Collaborative Learning in a Museum with PDAs\nYear: 2004\n\nAbstract: Using handheld devices in educational environments has begun to be recognized as suitable. Due to the drastic revisions in Japanese curriculum standards for elementary school children, new theories, systems and practices to support children in their learning are required. Therefore, we focused attention on science museums, which are different learning environments from schools. In this paper, we propose a system called Musex, which is used to support children in learning and exploring collaboratively in a museum with two PDAs (Personal Digital Assistants). Through Musex, children can collaboratively challenge some questions which are related to exhibitions. Solving the questions let children pay their attention to exhibitions naturally and understand contents of exhibitions more. We evaluated the system in a Japanese science museum and confirmed its effectiveness.","Title: Puppet theater system for normal-hearing and hearing-impaired people\nYear: 2012\n\nAbstract: We are developing Puppet Theater system which enables both the hearing impaired and the normal hearing to enjoy a puppet show. This system projects puppet's lines in balloon on the background. In addition, the system has a function that presents branches of the story to audience and allows them to select. We performed the system to elementary school pupils with hearing impairment and found that the pupils enjoyed it. Effects of the function were investigated with questionnaire. This paper describes the function and the result of questionnaire.","Title: Big Fat Wand: A Pointing Device for Open Space Edutainment\nYear: 2009\n\nAbstract: This paper presents principles, functions, and experiments of a new edutainment tool: Big Fat Wand (BFW). BFW is developed from a conventional laser show device, however, it is modified to a small enough one to be used at an open apace. BFW is connected to a laptop PC, which provides character, symbol images, and/or animations. From experimental results, we conclude that BFW is a good gear for a facilitator to educate and educate hearing-impaired students.","Title: Towards the Integration of Physical and Virtual Worlds for Supporting Group Learning\nYear: 2000\n\nAbstract: In this paper, we describe a system that integrates physical worlds (physical cities) and virtual worlds (digital cities), and its applications to supporting group learning. We have so far constructed several systems for supporting collaborative learning. One of the aims of CSCL (Computer-Supported Collaborative Learning) is to promote mutual learning through interactions and discussions among learners. Our previous experiments, however, have shown that these systems may not be so effective for supporting interactions and discussions at times. In order to enhance interactions further, a system should support externalization of each learner in an easily recognizable manner. Through such externalization, learners can actively collaborate or conflict with each other through discussions. The proposed system integrates a board game and a computer simulation, is used for studying urban planning and environmental problems. Each learner externalizes and represents his/her own ideas on a board game, which allows him/her to actively participate in a learning situation and to share the representations with other learners. The computer simulation calculates and visualizes the status of the city being constructed on the board game, in terms of air pollution, water pollution, etc.. Thirty fifth-grade pupils who had studied environmental problems in school participated in the experiments. The experiments showed that our system is effective for enhancing interactions, activating discussions, and raises learners' engagement.","Title: Practice! YUBIMOJI AIUEO for Japanese Hand Language Learning\nYear: 2004\n\nAbstract: In paper, we describe a PC-based Japanese hand alphabet learning system: Practice! Yubimoji AIUEO (PYA) to let ordinary elementary school pupils learn basic character expressions (AIUEO) of the Japanese hand characters (Yubimoji). PYA is a very simple system both from technical and educational points of view. Experiments in an elementary school shows that pupils have really enjoyed the system and learning, thus, we believe PYA is effective as an edutainment tool.","Title: Visitor movement as implicit human-computer interactions in museums\nYear: 2008\n\nAbstract: This paper outlines a novel location-based visitor assistant system in museums. It introduces visitor movement as a user-friendly and natural mechanism for enabling visitors. It enables visitors to explicitly or implicitly select annotation content about the exhibits and answer quizzes about their knowledge by their moving to specified spots in a museum. We operated the system at a science museum in Japan and received many positive evaluations from visitors.","Title: KIKIWAKE: sound source separation system for children-computer interaction\nYear: 2013\n\nAbstract: In general living environments, in order to separate children's voices from backgrounds noise, we developed a sound separation system by a microphone array. We created a game by use of this developed system, and conducted evaluation experiment intended for elementary school children. As a result, we confirmed this system could separate 3 voices, and the game promotes children's interest in or concerns about a microphone array in a quantitative way.","Title: Toward an Interactive Museum Guide System with Sensing and Wireless Network Technologies\nYear: 2002\n\nAbstract: In this paper, we describe an interactive guide system for kids in museums. The system uses a sensing board which can rapidly recognize types and locations of multiple objects, and creates an immersive environment by giving users visual and auditory feedback to their manipulations on the board. The purpose of the system is to attract users' interests in a real exhibition by allowing them to interact with the corresponding virtual exhibition on the board, and providing them with its information. We have evaluated the system in a museum. From the interviews and questionnaires, we have confirmed that it is easy for kids to use the system and it can raise their motivation for visiting real exhibitions.","Title: A next-generation audio-guide system for museums \"soundspot\": an experimental study\nYear: 2007\n\nAbstract: This paper proposes the SoundSpot system, a location/user-dependent audio guide system to reduce many restrictions of existing audio-based annotations. It can track the positions of visitors and then only provide sound information to the limited spots around them. We experimented it in an elementary school, where students listened to annotations played by it and their understanding was evaluated. The result of the questionnaire based survey and their answers to the quiz regarding the contents of the sounds proved that the system had the possibility to enable users to enough listen to and understand the contents.","Title: Evaluation of the Dialogue Information Function of Interactive Puppet Theater: A Puppet-Show System for Deaf Children\nYear: 2013\n\nAbstract: We have developed Interactive Puppet Theater, a puppet-show system designed for use by deaf children. For this study, we conducted evaluation experiments to determine whether Interactive Puppet Theater helps these children to have an enriched viewing experience. The evaluation results showed that Interactive Puppet Theater could be an effective way to ensure that deaf children understand the characters' dialogue as they watch the puppet-show, and that it enables them to have an enjoyable viewing experience.","Title: Enjoyable \"LEGS\" system deepens children's learning in a zoo\nYear: 2010\n\nAbstract: The authors have developed a system called Learning Evolution in a zoo with GPS equipped mobile phones (LEGS). In the LEGS system, GPS-equipped mobile phones are used to learn about animals and their bodies from the viewpoint of evolution in a zoo. This system makes use of GPS-equipped mobile phones to display appropriate content about an exhibit by acquiring and saving information about a user's current position and his/her history of past activities. We examined differences between cases where junior-high students use the proposed system and where they use exhibition panels. As a result, we have found that using the LEGS system could activate students' thinking and communication, and serve to deepen their understanding of the learning content, so that students were able to enjoy animal observations.","Title: The sensing board enhanced by interactive sound system for collaborative work\nYear: 2004\n\nAbstract: In this paper, we describe a new sensing board system enhanced with audio devices. Our previous board system provides users with common display images using tangible pieces, thus, users collaboratively work with visual and tangible information. On the other hand, the proposed system is characterized by the functionality of the direct responses of both sounds and images from the contents. Using the system, we develop three application systems with the following objectives: (1) Users enjoy interaction of sounds and images; (2) Users have high level of engagement; and (3) Users enjoy personal sounds and images. We have carried out experiments to evaluate the benefits and have found that these systems enhance user engagement, participation, and continuous operation.","Title: A system for supporting group learning that enhances interactions\nYear: 1999\n\nAbstract: In this paper, we describe and evaluate a system for supporting group learning that enhances interactions among learners. To date we have constructed several systems for supporting collaborative learning. One of the aims of CSCL is to promote mutual learning through interactions and discussions among learners. Our previous experiments, however, have shown that these systems may not be so effective for supporting interactions and discussions at times. In order to enhance interactions further, a system should support externalization of each learner in an easily recognizable manner. Through such externalization, learners can actively collaborate or conflict with each other through discussions.The proposed system integrates a board game and a computer simulation, and is used for studying urban planning and environmental problems. Each learner externalizes and represents his/her own ideas on a board game, which allows him/her to actively participate in a learning situation and to share the representations with other learners. The computer simulation helps the learners to understand the status of the town constructed on the board game.Several experiments were carried out in a public elementary school. The results show that our system is effective for enhancing interactions, discussions and learner engagement.","Title: KEI-Time Traveler: A Virtual Time Machine with Mobile Phones for Learning Local History\nYear: 2009\n\nAbstract: KEI-Time Traveler is a kind of \"virtual time machine\" that requires only commercially available mobile phones with no hardware attachment. In reality, KEI-Time Traveler presents graphical images of a past scene within a given area, viewed from the location measured using GPS and with arbitrary viewing angles. Users can explore a virtual past world using this system. A promising application of KEI-Time Traveler is edutainment. We applied it for learning activities with a group of 34 junior high school students. They virtually visited a world of 1938, when a severe landslide disaster occurred. They were able to compare conditions now and in the past directly at places with which they were familiar. The design approach and evaluation of our edutainment practice are described herein. Technically, the system uses 3D-model-based graphics that can be updated continually. From an educational perspective, students truly enjoyed the experience. It was not merely fun: our system raised their motivation to learn about disaster prevention. We confirmed the edutainment effect based on evidence: user responses and recordings of their experiences.","Title: Evaluation of the Universal Puppet Theater Based on Inclusive Design Method\nYear: 2012\n\nAbstract: In this study, we have improved the Universal Puppet Theater. Improvements have been made to branching scenes in the story. The exploratory evaluation experiment was a within-subject comparison of the existing version and improved version of the system. The subjects were 53 hearing-capable fourth-grade elementary school children. The results of analysis showed that the improved version of the system with branching function was more effective interface than the existing version.","Title: Practice! YUBIMOJI AIUEO: An Edutainment System of Japanese Hand Alphabets for Elementary School Children\nYear: 2007\n\nAbstract: Practice! YUBIMOJI AIUEO (PYA) is an edutainment system to promote basic expressions of Kana characters (AIUEO) of Japanese hand alphabets (YUBIMOJI) to ordinary children at elementary school age. In this paper, we report how PYA is good in edutainment objectives based on the series of experiments at classrooms of Sumiyoshi Elementary School, in Kobe, Japan. The results have suggested that 1) even if the users do not like personal computers, they can use PYA and keep their interests, 2) PYA users keep the understanding about the hand alphabets longer, 3) they love the puppy hints and they are affective, and 4) they can memorize the character shapes. In one sentence: to use PYA is definitive.","Title: BESIDE: Body Experience and Sense of Immersion in Digital Paleontological Environment\nYear: 2015\n\nAbstract: We are developing an immersive learning support system for a paleontological environment within a museum. The system measures the physical movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment by adapting the surroundings according to these movements. As the first stage of this project, we have developed a prototype system that allows learners to experience the paleontological environment. Here, we evaluate the operability of the system, degree of learning support, and sense of immersion for primary schoolchildren. This paper summarizes the current system and describes the evaluation results.","Title: KIKIWAKE: participatory design of language play game for children to promote creative activitybased on recognition of japanese phonology\nYear: 2014\n\nAbstract: This study proposes a system for supporting the Shotoku Taishi game, which is a language play game that uses the voice of children. The Shotoku Taishi game is a group game in which multiple people presenting a problem vocalize different words at the same time and the respondents are required to guess what the combination of the words is. The authors developed and implemented a system using a microphone array to extract the voice of a specific person presenting a problem in this game. The participants were 36 elementary school students whose native language was Japanese. The results showed that the participants were enjoying the Shotoku Taishi game and that this group activity was a creative activity that deepened their awareness of the Japanese language.","Title: StampOn in a museum: helping children's scientific inquiry\nYear: 2014\n\nAbstract: This study proposes a mobile support system \\\"Stamp-On\\\" to promote elementary school children's scientific inquiry into museum exhibits. The unique characteristic of Stamp-On is its use of a stamp-shaped interface to connect exhibits and mobile device content in an extremely simple way. In this paper, we first describe the principles and implementation of the Stamp-On system. Then, we evaluate the performance of the Stamp-On system at a various rock exhibitions. For the evaluation, 35 Japanese sixth-grade elementary school children (aged 11-12) used the Stamp-On system. We recorded the actions and utterances of one of them during their scientific inquiry process. To clarify the effectiveness of Stamp-On, we have analysed the following two factors in the scientific inquiry processes: 1) observing subjects attentively and 2) interpreting information obtained through the observation. Based on these analyses, we conclude that Stamp-On is effective to promote scientific inquiry among children.p","Title: Immersive observation support system toward realization of \\\"interactive museum\\\": observing \\\"live\\\" extinct animals while walking in a virtual paleontological environment\nYear: 2014\n\nAbstract: The authors developed a computer-animated \\\"interactive museum\\\" to improve observers' levels of interest and immersion during the exploration of virtual paleontological environments. In the system, animals on the screen move in synchronization with the observer's actions, and hence, the observer feels as though he/she has entered a real-life paleontological environment. In this paper, in order to enhance the immersive experience, we upgraded the system based on the results of past preliminary evaluation. In the upgraded system, animals on the screen animate whenever an observer walks across the screen, and the animal under observation changes in response to the observer walking backward or forward towards the screen. In this way, the observer becomes part of the virtual paleontological environment. Then, in order to verify the upgrade's effectiveness, we conducted an evaluation. The results indicated that the upgrade of the system was effective in immersing observers because of the fidelity of the simulation and the enjoyment afforded by moving one's own body.","Title: Discovering how other pupils think by collaborative learning in a classroom\nYear: 2000\n\nAbstract: The authors have so far developed a system that supports collaborative learning and evaluated it in school education. The system integrates physical and virtual worlds to teach urban planning and environmental problems by game playing by the pupils themselves. Intensive experiments with the system have proven that it can support the externalization of learners' thinking, active participation, interactions among them, and discussions in a learning situation. The paper addresses the effects of collaborative learning, and discusses how pupils discover the way of thinking of other pupils during game play","Title: Balancing virtual and real interactions in mobile learning\nYear: 2011\n\nAbstract: KEI-Time Traveller is a kind of virtual time machine that merely requires the use of commercially available GPS phones. In reality, KEI-Time Traveller shows graphical images of a virtual past scene within a given area as viewed from the current location and with arbitrary viewing angles. Users can virtually explore the past world using this system. We applied it to junior high school students, twice. They virtually visited a world of 1938, when a severe landslide disaster occurred, but the designs of interaction with the virtual past world differed between the two fieldwork trials. By comparing the results, we discuss the design of the interaction and its effects on the fieldwork.","Title: Science Education Enhancement within a Museum using Computer-human Interaction Technology.\nYear: 2016\n\nAbstract: We are developing an immersive learning support system for paleontological environments in museums. The system measures the physical movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment by adapting the surroundings according to these movements. As the first step toward realizing an immersive learning support system for museums, Yoshida et al. developed and evaluated a prototype system. However, their system cannot learn about certain paleontological features such as the names of extinct animals and their characteristics. Therefore, we developed an improved version of this system that allows for an enriched knowledge of paleontological environments, focusing in particular on extinct animals and plants and the ecological environment. Here, we evaluate the systemâs learning assistant and immersive features insofar as they are directed toward children in primary school. This paper summarizes the current system and describes the evaluation results.","Title: Supporting Zoo Visitors' Scientific Observations With A Mobile Guide\nYear: 2016\n\nAbstract: This study proposes an observation guide to support zoo visitors' scientific observation of animals in motion by providing viewpoints through animations. One of the difficulties that visitors experience when observing animals is that they do not sufficiently understand the functions and behavior of the body parts of the animal they are seeing. The guide aims to enhance visitors' understanding by resolving this issue through the use of animations of the functions and behaviors of parts of animals' bodies. To evaluate the guide, we had kindergarteners and elementary school students use its contents on seals while observing their hind flippers, noses, and claws at the Asahiyama Zoo. Our finding was that the guide was an effective means to enhance the children's understanding of the functions and behaviors of these parts of the body.","Title: Live Biblia: Evaluation of a Support System with a Tangible Interface for Viewing Science Museum Exhibitions.\nYear: 2016\n\nAbstract: In this study, we present a museum exhibit guide system that uses a tangible user interface: Live Biblia. Based on the visitorâs learning interests, museum exhibits are sorted and mapped by the system. Thus, it is possible to create a unique viewing map for the visitor, unrestricted by the existing exhibit environment. We describe the development and evaluation of the implemented Live Biblia prototype, which provides exhibit information based on selected material objects. We conducted evaluation experiments to examine the systemâs effectiveness. The results suggest that the interface prototype using physical objects spurred participantsâ interest in paleontology and facilitated effective museum exhibit learning. Additionally, we found that presenting information in the prototype animation aroused the participantsâ motivation to learn and supported the viewing of not only the single fossil object but also the related museum exhibits.","Title: Preparatory development of a collaborative / interactive learning game using bodily movements for deaf children.\nYear: 2016\n\nAbstract: In this paper, we develop a collaborative/interactive learning game for deaf children. We developed two separate activities for the proposed game: 'jumping' and 'filling in the blanks'. These two activities are described in detail. Because deaf children tend to find it difficult to acquire voice information, we examined a system that supports the construction of an environment for deaf children in which collaborative learning is encouraged from the perspective of science education. The results of an evaluation confirm that the proposed game encourages collaborative learning among deaf children and improves their motivation to learn grammar.","Title: Multiple-Player Full-Body Interaction Game to Enhance Young Children's Cooperation.\nYear: 2016\n\nAbstract: We have developed a full-body interaction game that allows children to cooperate and interact with other children in small groups. The aim of the game developed in this study is to encourage cooperation between children. The game requires two children to jump together at the same time. In a series of experiments, we observed children using several strategies to coordinate the timing of their jumps, such as shouting to one another and watching each other. The results of a questionnaire to evaluate the proposed interactive game indicate that children strategize to cooperate with each other while enjoying the game. Therefore, the game enables children to cooperate with others using bodily movements.","Title: Participatory Design of UKIYO-E Game for Children to Support Art Appreciation Based on Interacting with Pictures.\nYear: 2016\n\nAbstract: We are developing an art-appreciation system that will provide learning information about pictures while generating interest in the pictures themselves. This system can provide learning information on pictures by talking to an artist or people portrayed in the pictures using voice recognition. Furthermore, the system operates through movement and location of the user, and it generates sensation such that the user feels he/she is in the pictures, thus actively appreciating the pictures. As the first step toward this system, we have developed a system that provides learning information to the user by actively talking using ukiyo-e. Here, we quantitatively evaluate this system for primary schoolchildren and determine whether the user is interested in the pictures while talking to the pictures using voice recognition measured by electrodermal activity. In this paper, we summarize the current system and describe two evaluation results.","Title: Proposal for science learning materials using a \"VibGrip\".\nYear: 2015\n\nAbstract: We created a new hearing device called \\\"VibGrip(VG)\\\". The name VG came from the concept of Vib(ration) Grip. The VG has 5 piezoelectric elements mounted on a small housing that make it possible to feel the vibrations of different frequency bands with each finger. As an application of this device, we have developed a system that can sense the difference in sounds made by insects. Using a combination of speakers and the VG, we expect that a person with hearing impairment will be able to sense the information from the sounds more clearly.","Title: Experience-based learning support system to enhance child learning in a museum: touching real fossils and \"experiencing\" paleontological environment.\nYear: 2015\n\nAbstract: This paper presents a support system to assist learning within museums. Museums represent important places of scientific learning for children. However, because the main learning method in museums is the study of displayed specimens and their corresponding explanations, the motivation of a child to learn is low. Hence, we are developing an experience-based learning support system such as entertainment that will enable learners to enhance their motivation to learn in any museum. We develop two systems to realize experience-based entertainment. One is \\\"Live Biblia,\\\" which is a digital installed book system that uses real fossil. Another is the immersive learning system we called \\\"Body Experience and Sense of Immersion in Digital paleontological Environment\\\" or \\\"BESIDE,\\\" which enables learners to explore a virtual paleontological environment. In this paper, we present a summary of the current system of Live Biblia and BESIDE.","Title: A Full-Body Interaction Game for Children with Hearing Disabilities to Gain the Immersive Experience in a Puppet Show.\nYear: 2015\n\nAbstract: In this study, we developed a full-body interaction game that assists children with hearing disabilities in experiencing a puppet show by immersing in it. The full-body interaction game presents a type of puppet show that offers opportunities for the audience to interact with the drama. It is designed so that children with hearing disabilities can participate through known communicative movements; it allows children to easily grasp how their movements affect the progress of the story. The experiment results indicate that participating children enjoy the interaction game, and that the system allows the world of the story in the puppet show seem more real.","Title: Integration Of Ultrasonic Sensors And Kinect Sensors For People Distinction And 3d Localization\nYear: 2013\n\nAbstract: The method proposed here for 3D position measurement and identification of individuals by integrating ultrasonic and Kinect sensors uses ultrasonic transmitter tags with unique identifiers. Ultrasonic sensors measure the 3D positions of and identify tagged individuals, but cannot make measurements if there are no receivers in the direction of ultrasonic waves from transmitters. Kinect sensors measure 3D positions of individuals and track them with OpenNI, but Kinect sensors cannot make measurements if occlusion occurs due to the overlapping of individuals. Evaluation results show that the method proposed here is more robust than methods only using either ultrasonic or Kinect sensors.","Title: Depth information based separation of moving speakers' voices from mixed recordings.\nYear: 2016\n\nAbstract: This paper proposes a method for separating the voice of a signal person from the voices of multiple speakersu0027 in a mixed recording. When the sounds of multiple speakers are present when a voice recognition system is operating, the quality of speech recognition decreases. The proposed method separates the sound of multiple speakers using signal processing techniques and a microphone array. The position of the speaker is also required; however, the microphone array cannot be used for this purpose. Consequently, the position of the speaker was determined using the Kinect V2 depth image sensor. An experiment was performed to separate a signal voice from many voices. The results of the experiment show that, it is possible to separate two voices using the proposed technique.","Title: Interactive Objet D'Art Based On Iot Technology\nYear: 2016\n\nAbstract: Applying Internet of Things (IoT) technology to art can open up new possibilities for the interaction between systems and humans. In this study, interaction between appreciators and fine art was realized using IoT technology. Raspberry Pi, a low-cost credit card-sized single-board computer, was used to enable appreciators to change animations displayed onscreen in fine art using physical movement. This paper reports on our realization of interaction between appreciators and objet d'art using IoT technology and describes a demonstration conducted via an exhibition that was open to the public.","Title: Belong: Body Experienced Learning Support System Based On Gesture Recognition Enhancing The Sense Of Immersion In A Dinosaurian Environment\nYear: 2017\n\nAbstract: As the first step toward realizing an immersive learning support system for museums, Yoshida et al. developed and evaluated a prototype system. However, this system was problematic in that it could only be operated by using simple body movements. Moreover, the other problem was that learning about paleontology itself cannot be performed only by learning about a paleontological environment. Therefore, we developed an immersive learning support system \"BELONG\" as an upgraded version of the above-mentioned system. Using a recognizer capable of gesture recognition, the system can be operated using complicated body movements. The improved system enables learners to enhance their sense of immersion in a paleontological environment and learn about the fossil itself and its paleontology. This paper summarizes the prototype of \"BELONG\" and describes the experiments that were performed to evaluate its ability to achieve learning support and immersion.","Title: Preliminary Evaluation Of A System For Helping Children Observe The Anatomies And Behaviors Of Animals In A Zoo\nYear: 2017\n\nAbstract: In order to support children's scientific observation in zoos, we developed a system for helping children to observe the anatomies and behaviors of animals. This system provides viewpoints for observation via animations. Observing the anatomies and behaviors of animals is related to scientific observation. As a case study, we developed a system for learning about penguins and held a workshop at Kobe Municipal Oji Zoo. At the workshop, 19 elementary students used the system and observed how penguins swim and walk along with the skeletons of their legs and flippers. We examined the evaluations of children's enjoyment of this system. They responded to five items on their feelings about using this system on five-point scales. The number of affirmative responses was found to be more in number than neutral or negative responses. Children were able to enjoy using this system for observing the anatomies and behaviors of animals in a zoo.","Title: Development Of An Automatic Location-Determining Function For Balloon-Type Dialogue In A Puppet Show System For The Hearing Impaired\nYear: 2017\n\nAbstract: People with hearing impairments have a tendency to experience difficulties in obtaining audio information. They have difficult to watch puppet shows. In this study, we have undertaken the development of a dialogue presentation function in a puppet show system for the hearing impaired. The dialogue presentation function that was developed is an automatic location-determination system for balloon-type dialogue. The balloon-type dialogue turns the lines of dialogue into text and displays it as balloons in the background animation of the puppet show. This function automatically places the balloon-type dialogue in the vicinity of the locations of the puppets. In the evaluation test, 24 college students with a hearing impairment were used as participants, and a comparison was made between a system that implemented the automatic location-determination function for balloon-type dialogue and a system that did not implement said function. These results indicate the effectiveness of the location tracking function for balloon-type dialogue as a means for ensuring access to audio information in puppet shows.","Title: Development Of Experiential Learning System Based On The Connection Between Object Models And Their Digital Contents Collaboration Between Tangible Interface And Computer Interaction\nYear: 2017\n\nAbstract: Experiential learning is effective for educating children. However, there are many issues associated with this technique. In this study, we describe the development of a learning support system using which learners can experience touching and viewing in real and virtual environments. In the first stage of our study, we develop a larval mimesis experience system consisting of a Kinect sensor, larval models, and load sensors. The system is controlled using Arduino. Using the proposed system, learners can exercise full body interaction in the virtual environment; specifically, they can experience how larva models are observed in the real environment. The operation of this system was experimentally evaluated by learners from a primary school. The results indicate that the system is suitable for the use of children. In addition, the effectiveness of the learning support was evaluated by using a questionnaire. This paper summarizes the development of the proposed system and describes the evaluation results.","Title: Development Of Gesture Recognition Sub-System For Belong Increasing The Sense Of Immersion For Dinosaurian Environment Learning Support System\nYear: 2017\n\nAbstract: We are developing an immersive learning support system for paleontological environments in museums. The system measures the body movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment. Conventional systems are only able to recognize simple body movements, which is insufficient to completely immerse learners in the paleontological environment. On the other hand, when they need to perform complicated body movements, learners move their bodies eagerly while thinking. This emphasizes the importance of developing a sub-system capable of recognizing complicated body movements. In this paper, we describe a sub-system developed to recognize the body movement of the most important learner in the immersive learning support system.","Title: Satoyama: Time-Limited Decision Game For Students To Learn Hundreds Years Forestry Management\nYear: 2017\n\nAbstract: Global environmental problems continue to worsen. In this situation, it is important to understand and experience changes in the natural environment in realistic ways. However, it was difficult to experience these changes in real time because they happen over large time scales. To overcome this problem, the authors developed a game-like learning tool that enables players to learn about vegetation succession. This game is Windows-based and enables players to simulate the conservation of SATOYAMA, rural natural areas. The player selects the actions within a designated time and the vegetation succession of the SATOYAMA changes according to that action. At the end of this game, the score is based on the SATOYAMA conserved by the player. Thirty-seven students participated in this experiment whose result suggested that this game would enable children to develop an interest in vegetation succession and motivate them to learn about it.","Title: Laughing voice recognition using periodic waveforms and voice-likeness features.\nYear: 2016\n\nAbstract: With a goal of advancing human-machine collaboration, we propose a method to recognize a laughing voice. A previous study that proposed a laughing voice recognition method was based on the periodic waveform feature of the laughing voice. However, identifying laughing voices from waveforms is problematic, because this can result in false positive results. To overcome this problem, we propose a laughing voice recognition method that incorporates a voice-likeness feature. In addition, we make a laughing voice recognition system using our proposed method. To confirm the efficacy of the laughing voice recognition method, we evaluated this system. In our evaluation, we were able to correctly recognize laughing voice at a high success rate of 97%. In comparison with the previous study, the recognition rate improved by 18%; therefore, our proposed method can be considered an effective in recognizing laughing voice.","Title: Children'S Evaluations Of A System Supporting Observation Of Anatomies And Behaviors Of Animals In Zoos\nYear: 2017\n\nAbstract: In order to support children's observation and taxonomic judgment in zoos, we developed a pilot system to provide animated visualizations of the anatomy and behavior of penguins. Nineteen children observed penguins and a penguin skeleton. We examined the children's evaluations of this system by conducting interviews. Most evaluations were positive; for example, the system helped children understand penguin anatomy and behavior, which they could not observe just by watching live penguins. From children's evaluations, the system was found to be useful.","Title: Novel Application Of Spherical Microphone Array Sensor With Three-Dimensional Directivity For Home And Office Environments\nYear: 2015\n\nAbstract: Interest in sound interfaces is increasing because such interfaces do not need advanced knowledge about particular devices, nor do they require physical operation. However, such interfaces are difficult to use because the general living environment often contains background noise. In order to solve this problem, sound separation systems that use a microphone array sensor have been proposed. In previous work, this microphone array sensor was a small system that considered only two-dimensional (2-D) directivity control. In this paper, we present the design of a spherical microphone array sensor with 3D directivity. This 3-D directivity property is confirmed via an experimental evaluation.","Title: Novel application of a range image sensor to eye gaze estimation by using the relationship between face and eye directions\nYear: 2015\n\nAbstract: In this study, we estimate gaze direction using the relationship between the face and eyes. The face and eyes are divided laterally and in lengthwise direction. We set up an object laterally and in lengthwise direction and measured the face angle using a Kinect sensor, which is range image sensor, when gazing at an object. The angle of the eyes is fixed at the angle of the object and grasp of the relationship between face and eyes. We calculate the gaze direction using the relation between the face and eyes. Then, the results of present experiment, if based on relationship between face and eyes, has been shown to be effective though the results of the experiment.","Title: Electrodermal activity based study on the relationship between visual attention and eye blink\nYear: 2015\n\nAbstract: In this paper, the relationship between visual attention and eye blinking is described. In our experiment, we observed blinking when a subject performed a task. We determined that the subjectu0027s visual attention functions during the task by electrodermal activity. Experimental results showed that blink rate decreased when the subjectu0027s visual attention was engaged. On the other hand, blink rate increased when the subjectu0027s visual attention shifted from attentive to inattentive. These findings enable a more objective evaluation of the relationship between visual attention and blinking when determining by electrodermal activity whether visual attention is engaged.","Title: Novel application of Kinect sensor to support immersive learning within museum for children\nYear: 2015\n\nAbstract: This paper presents a system to support learning within museum for children as a novel application of Kinect based human sensing system. The system measures the physical movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment by adapting the surroundings according to these movements. As the first stage of this project, we have developed a prototype system that allows learners to experience the paleontological environment. Here, we evaluated the performance of the sensor of BESIDE in order to confirm whether or not this system can put into practice BESIDE at the museum. This paper summarizes the current system and describes the evaluation results.","Title: Implementation and Evaluation of a Wide-Range Human-Sensing System Based on Cooperating Multiple Range Image Sensors.\nYear: 2019\n\nAbstract: A museum is an important place for science education for children. The learning method in the museum is reading exhibits and explanations. Museums are investing efforts to quantify interests using questionnaires and sensors to improve their exhibitions and explanations. Therefore, even in places where many people gather, such as in museums, it is necessary to quantify people's interest by sensing behavior of multiple people. However, this has not yet been realized. We aim to quantify the interest by sensing a wide range of human behavior for multiple people by coordinating multiple noncontact sensors. When coordinating multiple sensors, the coordinates and the time of each sensor differ. To solve these problems, coordinates were transformed using a simultaneous transformation matrix and time synchronization was performed using unified time. The effectiveness of this proposal was verified through experimental evaluation. Furthermore, we evaluated the actual museum content. In this paper, we describe the proposed method and the results of the evaluation experiment.","Title: Implementation And Evaluation Of Accessible Caption System In Universal Puppetry: A Case Study On Hearing Impaired Children At The Elementary School Of Deaf\nYear: 2017\n\nAbstract: This study tested and evaluated two functions developed as a part of the balloon-type caption display system in a universal puppetry. Two functions are the automatic location-determining function and the emotional expression function. The automatic location-determining function is feature that make captions positioned according to the positions in which the puppets move. And emotional expression function changes the shape of balloons that represents emotions such as joy, anger, sadness, and pleasure. We conducted the evaluation experiment. Participants are fifteen students with hearing impairments from the elementary school of deaf. The result shows the effectiveness of the automatic location-determining function and the emotional expression function as a means to compensate for vocal information in puppetry for hearing impaired children.","Title: Novel application of 3D range image sensor for estimation of interests based on fixation time of face orientation\nYear: 2017\n\nAbstract: In this paper, we describe the relationship between the presence or absence of interest and the fixation time of face orientation. There is a conventional method of measuring the fixation time of line-of-sight orientation to prevent accidents due to carelessness. In addition, studies are being performed on the estimation of the relationship between face orientation and line-of-sight orientation. However, even if face and line-of-sight remain, it has not been confirmed whether people are interested. Therefore, we conducted experiments to investigate the relationship between the presence or absence of interest and the fixation time of face orientation. We simultaneously measured the change in interest and face orientation with time as subjects watched two movies. As a result, it was suggested that face orientation remained longer for an object of interest.","Title: Accuracy evaluation of hand motion measurement using 3D range image sensor\nYear: 2017\n\nAbstract: Techniques capable of measuring hand motion are expected to be applied in various situations. Examples are the practice support systems used in activities such as sport and dance, for instance, the system employed in baseball pitching form analysis. This analysis evaluates the state of the throwing form numerically and visually by measuring the velocity and trajectory of the hand. This requires measurement of the hand by a sensor and is accomplished by using a motion capture system as the method for measuring hand motion with high accuracy. However, it is time consuming to prepare the system. Therefore, a 3D range image sensor, which is inexpensive and easy to prepare, is proposed. However, as the actual measurement accuracy of this sensor is unknown, it was evaluated by calculating the error with the measured value of motion capture as the true value. In this research, we calculated the error between the 3D coordinates and velocity to evaluate the error. As a result, the effectiveness of the measurement accuracy of the hand motion by the 3D range image sensor was confirmed. The results suggest that the 3D range image sensor can be used in various situations involving human activity.","Title: Novel application of microphone array sensor for children's language learning support — Intelligent Interactive Design using voice separation and recognition system —\nYear: 2015\n\nAbstract: Development of a robust and precise voice interface could accelerate the realization of a learning support system that utilizes voice. In our research, this objective is called Intelligent Interactive Design of learning support. In order to realize Intelligent Interactive Design, we propose a “voice separation and recognition system” that aims at clear voice separation for robust voice recognition by voice recognition systems. The results of experiments conducted indicate that our Intelligent Interactive Design has a correct voice recognition rate above 70%. The results are highly satisfactory and indicate that Intelligent Interactive Design can be realized via our proposed system in the near future.","Title: Novel Application of 3D Range Image Sensor to Caloric Expenditure Estimation based on Human Body Measurement\nYear: 2018\n\nAbstract: The number of diabetic patients are increasing worldwide. Increasing calorie expenditure is one of the methods to prevent diabetes. Measuring the current calorie expenditure can improve awareness in daily life and help increase calorie expenditure. Conventional research has estimated calorie expenditure using an acceleration sensor. However, in contact sensors such as acceleration sensors, the estimation accuracy changes with the mounting position. Therefore, we aim to estimate calorie expenditure using non-contact sensors that do not need to be worn by the user. In this study, we conducted experiments to evaluate the effectiveness of estimating calorie expenditure using a 3D range image sensor, which is a non-contact sensor. The effectiveness of the proposed method was verified by the results of the evaluation.","Title: EDA Sensor-based Evaluation of a Vegetation Succession Learning System\nYear: 2018\n\nAbstract: There are many forest problems that need to be solved to move toward a sustainable society; therefore, educating people, especially children, about forest problems is very important. Although schools conventionally educate children through textbooks, children are not expected to learn about forest problems actively from only textbooks. Therefore, this study develops game-type learning material that enables students learn complex mechanisms of vegetation succession and the actual state of succession, while taking interest in forest problems, by performing forest management themselves. For evaluation of the system, we measure the electrodermal activity (EDA) because using a conventional questionnaire can only qualitatively evaluate whether learning using the system is more interesting than when using text. EDA sensors are used to measure physiological response of participants reading texts and those using the system; the interest when using the system is evaluated quantitatively. The experiment shows that the change of EDA increases when using the system, which suggests that using the system is more interesting and can be better for learning than reading text.","Title: Application of 3D Range Image Sensor to Body Movement Detection : Supporting Children’s Collaborative Learning in Museums\nYear: 2018\n\nAbstract: This paper presents a collaborative learning system to support the learning experience of children in museums. The proposed system uses the Kinect Sensor for human sensing tasks required for delivering an interactive learning experience. The study recognizes that museums are an important source of scientific knowledge as they facilitate experiential and conversational learning. However, the main learning method in museums is passive-observing exhibits and reading explanations on text panels. Thus, few opportunities exist for children to discuss the experience and engage in conversations, thereby limiting the learning experience for children. Therefore, we developed a Kinect sensor based collaborative immersive learning support system for a museum that enables children to learn through body movements and conversation. In addition, we developed interactive content that can be manipulated by children using body movements. In this manuscript, we describe the outline of the system under development. In addition, we demonstrate using experiments that the Kinect sensor can be applied to accurately recognize the body movement of multiple users; this can be regarded as the first step towards realizing a cooperative learning support system for museums.","Title: Effectiveness of Multisensory Methods in Learning Onomatopoeia for the Hearing-Impaired.\nYear: 2018\n\nAbstract: We examined the effectiveness of multisensory methods in learning animal sounds and the onomatopoeia that describe them. Hearing-impaired individuals find it difficult to learn onomatopoeia because they have limited or no access to auditory information. To address this problem, we developed a device that converts audio information into vibrations, and attempted to broaden the experience of sound by using multisensory methods to stimulate the senses of sight, hearing, and touch. In the rhythm discrimination test using the device, the hearing-impaired group showed better performance with vibration added to the audio information than without vibration. In addition, we designed a science lesson to help hearing-impaired individuals learn cicada songs. This lesson used multiple media including text, images, sounds, sound waveforms, onomatopoeia, and vibrations. The evaluation results showed a significant difference between the students who were able to distinguish the vibrations and those who could not. The former reported that they found the lesson enjoyable and that it was a useful way to learn science.","Title: Color Held Illumination Map Estimation using GAN for Low-light Image Enhancement\nYear: 2022\n\nAbstract: Recently, museum learning has attracted considerable attention. Guide robots that detect exhibits are being used to enhance learning effects. However, detecting exhibits in the dark areas of the museum is difficult. Therefore, it is necessary to enhance low-light images. In this study, we present an image enhancement method, color held illumination map estimation (CHIME) using generative adversari...","Title: Playing with invisible animals: An interactive system of floor-projected footprints to encourage children’s imagination\nYear: 2022\n\nAbstract: Playing is essential for a child’s development, and it has various positive effects. In particular, playing with toys enhances children’s imagination. In recent years, children have been tending to play with smart toys equipped with built-in computers, which present various advantages that leverage their digital characteristics. For example, smart toys can provide augmented reality functionalities through which digital information can be added to physical reality. These characteristics offer an important benefit of stimulating the interest and presence of children. However, wearable devices may be required to realize this. Wearable devices are ineffective when people do not own or cannot wear them. Therefore, we developed a system that stimulates the imagination and interest of children in playing without any wearable devices. Our system projects animal footprints onto the floor, encouraging children to play with invisible animals based on their imagination from the footprints. The footprints respond to the children’s movements. To evaluate the developed system, we conducted several experiments with children. First, we investigated the fundamental effects of the system on elementary school students. Then, we investigated the different effects of various interactions. Our experimental results showed that the developed system encourages the imagination of children while playing."],"string":"[\n \"Title: KOTOHIRAGU NAVIGATOR: an open experiment of location-aware service for popular mobile phones\\nYear: 2006\\n\\nAbstract: We have developed a location-aware sightseeing support system for visitors to KOTOHIRAGU Shrine, using only popular mobile phones employing the gpsOne system. Its design is not a map-based navigation system, but a shared virtual world system like multi-player online role-playing games. We conducted an experiment recruiting 29 subjects from real tourists visiting the shrine, who had their own compatible GPS-phones. From the survey, we have found that location-aware sightseeing support system using mobile phones can be accepted by young people, but the generation gap is wider than expected.\",\n \"Title: To use PYA tool or not for learning Japanese hand alphabets\\nYear: 2006\\n\\nAbstract: We are developing an easy-to-use edutainment system: Practice! YUBIMOJI AIUEO (PYA). The objective is to promote basic expressions of Kana characters (AIUEO) of Japanese hand alphabets (YUBIMOJI) to ordinary children at elementary school age. PYA seems to work well from users' behaviors and responses, however, the effectiveness has not been fully confirmed, so far. In this paper, we have carried out series of intensive experiments at classrooms of Sumiyoshi Elementary School (7 or 8 years old; 83 subjects). The results are summarized as follows: 1) Devices the children use to learn do not affect the performance just after the study; 2) the PC use is effective when the target characters are complex and similar; and 3) The PC users keep remembering difficult shapes of characters after one month. These results have suggested that the use of PCs is superior to the ordinary oral lectures, however, it depends on the features of characters.\",\n \"Title: What you look like when learning hand alphabets\\nYear: 2005\\n\\nAbstract: When ordinary people learn hand languages, it is critical to properly understand that the forms of the hand shapes and moves are different for speakers and listeners. To cope with the issue, we have equipped a PC camera with the visual interface of an edutainment system for Japanese hand alphabets. To investigate the visual interface, we have conducted experiments with/without the camera device to measure the eye movement when subjects use the interface The experimental results have shown the effectiveness of the how-you-look-smart interface with a PC camera.\",\n \"Title: Design and evaluation of a virtual mobile time machine in education\\nYear: 2008\\n\\nAbstract: We have developed a \\\"virtual time machine\\\" for edutainment, which needs only commercially available mobile phones. In reality, the system just shows graphical images of a past scene within a given area, viewing from the location given by GPS and with arbitrary viewing angles. Users can virtually explore the past world with it. We applied it to junior high school students. They virtually visited a world of 1938, when a landslide disaster occurred. They were able to directly compare now and the past. In this paper, the design approach and evaluation of our edutainment practice are given. Our system raised students' motivations.\",\n \"Title: Design of an interactive system for group learning support\\nYear: 2002\\n\\nAbstract: In this paper we describe our project to design a system that can be used as a teaching aid to support group learning in elementary school education. The system enhances the learning outcome for pupils who have studied environmental problems using a textbook, by allowing them to construct a town in a physical space and to assess the construction through computer simulations. The system was designed in collaboration with teachers and their pupils in elementary schools. Lessons learned from the collaborative design processes are described.\",\n \"Title: A Laser Show Device Works in an Open Space for Hearing-Impaired Students\\nYear: 2008\\n\\nAbstract: The paper proposes a new pointing device for education of hearing-impaired students. The device: Big Fat Wand (BFW) is developed from a conventional laser show device, however, is modified to a small enough one to be used at out-of classroom lectures. BFW is connected to a laptop PC, which provides character, symbol images, and/or animations with the device through a conventional one board microcomputer. This paper describes the educational objectives, basic principles, and preliminary experimental results of BFW. We conclude that BFW is a good gear to improve the methodology to educate and educate hearing-impaired students.\",\n \"Title: Letting every pupil learn Japanese hand alphabets with VIUAL interfaces\\nYear: 2004\\n\\nAbstract: This paper discusses the effects of a visual interface for the Japanese hand language system. The system Practice! Yubimoji AIUEO (PYA) we are developing aims at letting ordinary pupils learn basic character expressions (AIUEO) of the Japanese hand characters (Yubimoji). Because very few pupils in Japan are currently able to communicate with handicapped people and there are only complex, expensive, and difficult software systems and/or textbooks available to learn the language system, it is critical to deliver easy-to-use software systems on a PC at elementary schools. This paper describes what are the principles of PYA, how PYA works, and why PYA is effective from pedagogical and computer human interaction points of view.\",\n \"Title: A system for supporting collaborative learning with networked sensing boards\\nYear: 2004\\n\\nAbstract: The authors have used sensing boards based on RFID technology to construct a face-to-face group learning support system integrating the physical world and the virtual world. The system is shown to be useful through performance in that a learner without sufficient skill in using a computer can easily participate in learning, and knowledge acquired through textbooks and the like can be tested in the physical world. On the other hand, some problems have been pointed out: the utterances depend more strongly on the leader, and learning support with a higher degree of realism is desired. Consequently, in the system proposed in this paper, multiple sensing boards are placed at different sites so that the learner groups can communicate face-to-face. The sensing boards are connected through a network so that the operations on the board can influence each other. The learners in the group gather around the board and try to solve the problem face-to-face. They also interact with the learners in another group through a chat system. The learners in a primary school classroom used the system to study city design and environmental problems, and the effectiveness of the proposed system was demonstrated. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(9): 39–50, 2004; Published online in Wiley InterScience (). DOI 10.1002/scj.10502\",\n \"Title: LEGS system in a zoo: use of mobile phones to enhance observation of animals\\nYear: 2009\\n\\nAbstract: In the LEGS system, GPS-equipped mobile phones are used to learn about animals and their bodies from the viewpoint of evolution in a zoo. This system identifies nearby animals, asks questions about the animals' bodies to enhance observation, provides navigations for the next observations, and summarizes several observed animals' parts from the viewpoint of evolution. 24 students (age: 14--15 years old) learnt about animals using the mobile phones in a zoo. We evaluated the system and found that it helped students explore, observe, and learn about animals' bodies independently in the zoo.\",\n \"Title: KEI-time traveler: visiting a past world with mobile phones to enhance learning motivation\\nYear: 2008\\n\\nAbstract: KEI-Time Traveler is a system using commercially available phones equipped with GPS. It enables students to do fieldwork with a visit to a past environment from the corresponding location in the present world. Students experienced such fieldwork to visit the site of a landslide disaster in 1938. We evaluated the system and found that KEI-Time Traveler enhanced motivation and helped students learn about their local area's history.\",\n \"Title: Multi-Audible table for collaborative work\\nYear: 2004\\n\\nAbstract: This paper presents a prototype Multi-Audible system. By Multi-Audible, we mean that plural users have a portable device to hear different audio information during the interaction. The proposed system is an interactive art system that sends auditory information to a user through the device based on the position of that user's finger on a table with touch screen functionality. We describe the hardware and software configuration, contents of the proposed system, and some midterm experimental results.\",\n \"Title: Symphony-Q: a support system for learning music through collaboration\\nYear: 2002\\n\\nAbstract: This paper describes the Symphony-Q support system for learning music. This system integrates a sensing board and a computer, and is used for collaborative learning in a face-to-face setting. One of the aims of Symphony-Q is to enhance music experiences: children who do not have music skills can easily participate in music learning, enjoy making sounds, and play rhythmically to music in collaboration with others. The paper discusses comments and feedback from school children and their teachers, which were collected during experiments with Symphony-Q carried out in a Japanese public elementary school.\",\n \"Title: Development and Evaluation of a Digital Vegetation Interaction Game for Children\\nYear: 2009\\n\\nAbstract: In this study, we develop a new digital sugoroku game that portray the phenomenon of vegetation succession in a forest. The results of the experimental evaluation showed that the game was effective in stimulating the interest of the students who participated in the game.\",\n \"Title: Learning by Doing: Space-Associate Language Learning Using a Sensorized Environment\\nYear: 2005\\n\\nAbstract: This paper proposes a Learning-by-Doing (LBD) system for assisting learners of English as a foreign language, by providing educational content generated based on real-world behaviors in a sensorized environment. The LBD system consists of an ultrasonic location sensing system developed by the authors and an educational content server. The location of the student is monitored by ultrasonic sensors embedded around the learning room. The system voices English verbs related to objects around the student so that the student can obtain the language skills for expressing various activities of everyday life in English by performing real-world behaviors. The system was implemented experimentally in an English language school. Six subjects participated in an experiment evaluating the educational efficacy of the proposed system. Recall rates of learned verbs were compared among three methodologies, \\\"Learning by text,\\\" \\\"Learning by pictures and text,\\\" and \\\"Learning by doing\\\". Recall rates were measured at the following intervals: soon after the learning task, 2 days after, 4 days after, 7 days after, and 14 days after the learning task. The results indicate that the proposed LBD system increased the recall rate of learned words by 113% 14 days after the learning task. Overall, the system significantly increased the average recall rate by 102% in comparison to the other learning methodologies.\",\n \"Title: The preliminary study of animation dictionary for onomatopoeic learning\\nYear: 2007\\n\\nAbstract: In this paper we discuss the effectiveness of animation dictionaries. We focus on a design solution to Japanese onomatopoeic accessibility problems for the children who are hearing-impaired. Our approach is to design educational materials for deaf or hard-of-hearing children at the learning of the onomatopoeic expressions, to make the best of their abilities rather than compensating for their disabilities. Our preliminary investigation suggests that the onomatopoeic expressions accompanied by animation would be able to transmit emotional images of words. The animations were more effective than text or video clips. We believe that an animation dictionary would be an effective educational material that is understandable by hearing-impaired children.\",\n \"Title: Experiments of entertainment applications of a virtual world system for mobile phones\\nYear: 2005\\n\\nAbstract: Using a virtual world system for GPS-phones, we have developed a small RPG-like game to give information to tourists. Comparing with other virtual systems for mobile terminals, the cost of our system is much lower because only phones on the current market are required but no additional devices are needed. The game follows a Japanese famous tale and a player plays as the hero. We recruited twenty subjects and they played it 35 minutes in average. Through evaluation sessions of the system, we have found that the system is highly evaluated as an entertainment system.\",\n \"Title: Vegetation interaction game: digital SUGOROKU of vegetation succession for children\\nYear: 2010\\n\\nAbstract: In this study, we redesign and develop a new digital sugoroku game based on the phenomenon of vegetation succession. A practical evaluation in an elementary school that consisted of game play and fieldwork activity was conducted. The results of the evaluation showed that the game was effective in stimulating the interest of the students who participated in the game, and was able to support their learning in a joyful way.\",\n \"Title: Interactive and enjoyable interface in museum\\nYear: 2005\\n\\nAbstract: Exhibitions at a scientific museum are usually difficult for ordinary school pupils. To improve the issues of current explanation systems, we use Personal Data Assistant (PDA) devices. Recent PDAs have enough functionality for people to interactively, individually, but it is not easy to assist that school pupils learn scientific knowledge merely using PDA.This research examined the main focus of the design and implementation of visual interfaces for PDAs for such a learning system. We aims the visual interface for PDAs have more interactive and entertainment to engage for learning scientific knowledge. Experiments using two prototype systems(Pi-book and Pit A Pat)implemented in the Flash/MX software toolkit have suggested the effectiveness on the performance and functionality of the proposed method.\",\n \"Title: Learning onomatopoeic expressions by animation\\nYear: 2007\\n\\nAbstract: This paper focuses on a design solution to Japanese onomatopoeic accessibility problems for the hard-of-hearing. Our research suggests that the onomatopoeic expressions accompanied by animation would be able to transmit emotional images of words. The animations were more effective than text or video clips. We believe that an animation dictionary would be an effective educational material that is understandable by hard-of-hearing students.\",\n \"Title: A Handy Laser Show System for Open Space Entertainment\\nYear: 2009\\n\\nAbstract: Big Fat Wand (BFW) is a handy laser show system, which includes a portable laser show device newly developed and a laptop PC with easy-to-use authoring toolkits. This paper describes basic principles and architecture of BFW, then demonstrates how BFW is used in an open space environment.\",\n \"Title: Making a Hands-On Display with Augmented Reality Work at a Science Museum\\nYear: 2013\\n\\nAbstract: In this paper, we propose an augmented reality (AR) system with a laser projection device as a hands-on display at a science museum. The AR system provides virtual information, which learners can control for a visual explanation about an exhibited item. Learners develop their knowledge and understanding through the display without any modification to the item and/or the existing displayed explanation. We conducted an experiment using the AR system, with child visitors to Gamagori Museum of Earth, Life and the Sea. AR systems should meet the following criteria if they are to be considered effective: i) the display should make learners interested in the exhibited item, ii) learners should be able to easily handle the AR display, and iii) learners should construct their knowledge through using the display. In our experiment, we evaluated the AR display against these criteria. We conclude that the AR display system enables learners to construct their knowledge in reality, and that the system encourages learners' interest in the exhibited items.\",\n \"Title: Electronically enhanced board games by integrating physical and virtual spaces\\nYear: 2002\\n\\nAbstract: This paper describes an electronically enhanced board called E 2board. The motivation of our work comes from a traditional board game, which groups of players enjoy in a face-to-face situation by manipulating pieces on a physical board. In order to enhance users’ excitement and immersiveness, a physical board and a virtual world created by a computer are linked together with E 2board. An important function of E 2board is the rapid recognition of massive numbers of different objects. The authors have developed several applications using E 2board: not only games, but also systems for supporting group activities. Some of these applications are shown.\",\n \"Title: Edutaining school pupils for Japanese hand alphabets\\nYear: 2004\\n\\nAbstract: This paper presents Practice! Yubimoji AIUEO (PYA) to let ordinary elementary school pupils learn basic character expressions (AIUEO) of the Japanese hand characters (Yubimoji). PYA at a Personal Computer has an easy-to-use and look-and-feel visual interfaces. This paper describes what are the principles of PYA, how PYA works, and why PYA is effective from the edutainment view.\",\n \"Title: CarettaKids: a system for supporting children's face-to-face collaborative learning by integrating personal and shared spaces.\\nYear: 2006\\n\\nAbstract: We developed a new system called CarettaKids that supports face-to-face collaborative learning by children. CarettaKids uses a sensing board based on the Radio Frequency Identification (RFID) technology to support collaboration in a shared space, and the Personal Digital Assistant (PDA) device to support activity in personal spaces. We also introduced this system into an actual classroom environment to evaluate its performance in support for children's collaborative learning, by analyzing the childrens' interaction. As a result, we have confirmed that CarettaKids's feature of transition between two spaces, makes it possible for children to reflect on problems detected in the shared space so as to find solutions in their respective personal space, and to engage in an active exchange of opinions in the shared space, based on ideas generated from personal-space learning.\",\n \"Title: Development of a Full-Body Interaction Digital Game for Children to Learn Vegetation Succession\\nYear: 2013\\n\\nAbstract: In this study, we developed a simulation game called \\\\\\\"Human SUGOROKU\\\\\\\" that simulates vegetation succession of the real forest area in the virtual world. This game consists of a full-body interaction system to enable children to enjoy and learn vegetation succession by playing with their body movement. We conducted an experiment with children and investigated the effects of the full-body interaction through interviews. The results showed that the full-body interaction promotes a sense of immersion in the game. This paper describes the structure of this system and the interview results.\",\n \"Title: Fostering students' participation in face-to-face interactions and deepening their understanding by integrating personal and shared spaces\\nYear: 2007\\n\\nAbstract: In this research, we introduced CarettaKids into the social context of a classroom environment to evaluate whether integration of personal and shared spaces can help promote students' participation in synchronous/co-located interactions in the classroom and deepen their understanding of subject matter. Analysis of videotaped interactions and pre-and posttests clarified the following three points. (1) Students who used CarettaKids presented the simulation results and rules for object arrangement they worked out individually in their respective personal space, by using CarettaKids' function of projecting object arrangements and simulation results from a personal digital assistant onto a sensing board. (2) Many of the students who used CarettaKids examined individually generated ideas collaboratively in the shared space. The patterns of collaborative examination are: (a) Induce a rule for object arrangement from object arrangements devised in personal spaces; (b) Deduce a new object arrangement from the rules discovered in the personal spaces; and (c) Refine the rules discovered in the personal spaces through group discussion. (3) Students who used CarettaKids not only considered all of the three factors, i.e. residential area, industrial area and forest area, but also understood relations between these factors, thereby deepening their understanding of city planning that takes environmental and financial aspects into consideration. We suggest that the degree to which students deepen their understanding is affected by the presence or absence of collaborative examination of individually generated ideas in the shared space.\",\n \"Title: Design and Evaluation of a Location-Based Virtual City System for Mobile Phones\\nYear: 2005\\n\\nAbstract: We are developing a virtual city system with a model that consists of virtual architectural objects and virtual creatures, geographically overlaid onto the real world. People who have mobile terminals with location sensors like GPS can visit the virtual city when walking about in a real city. The most important aspect of our research is that we have adopted current market mobile phones. In this paper we describe a prototype of virtual city system and its evaluation. The result of evaluation suggests that subjects were very much interested in the virtual city system. Technical problems have been revealed by the evaluation but most of them will be solved or minimized if we use the next generation of mobile phones.\",\n \"Title: Open experiments of mobile sightseeing support systems with shared virtual worlds\\nYear: 2006\\n\\nAbstract: In this paper, we describe results from the experiments of a location-dependent shared virtual world system applied to sightseeing entertainment. This system can be used with GPS-phones on the current Japanese market. Users can enjoy interacting with virtual objects including virtual animals/agents. Subjects of the experiments were real tourists who had their own GPS-phones compatible with our system. We found that evaluations on the system varied depending on age, gender, and experiences of subjects. Results from the experiments gave suggestions on prospective users and service design.\",\n \"Title: Human SUGOROKU: learning support system of vegetation succession with full-body interaction interface\\nYear: 2014\\n\\nAbstract: In this study, we developed a simulation game called \\\"Human SUGOROKU\\\" that consists of a full-body interaction system to enable elementary school students to enjoy and learn vegetation succession. The students' sense of immersion is improved by enabling them to play this game using their body movements. We conducted an experiment with the students and investigated the affects of the full-body interaction through questionnaires. The results showed that the full-body interaction promotes a sense of immersion in the game and enhance their understanding of vegetation succession. This paper describes the structure of this system and the questionnaires results.\",\n \"Title: Human SUGOROKU: full-body interaction system for students to learn vegetation succession\\nYear: 2013\\n\\nAbstract: In this study, we developed a simulation game called \\\"Human SUGOROKU\\\" that consists of a full-body interaction system to enable elementary school students to enjoy and learn vegetation succession. The students' sense of immersion is improved by enabling them to play this game using their body movements. We conducted an experiment with the students and investigated the affects of the full-body interaction through interviews. The results showed that the full-body interaction promotes a sense of immersion in the game. This paper describes the structure of this system and the interview results.\",\n \"Title: Musex: A System for Supporting Children's Collaborative Learning in a Museum with PDAs\\nYear: 2004\\n\\nAbstract: Using handheld devices in educational environments has begun to be recognized as suitable. Due to the drastic revisions in Japanese curriculum standards for elementary school children, new theories, systems and practices to support children in their learning are required. Therefore, we focused attention on science museums, which are different learning environments from schools. In this paper, we propose a system called Musex, which is used to support children in learning and exploring collaboratively in a museum with two PDAs (Personal Digital Assistants). Through Musex, children can collaboratively challenge some questions which are related to exhibitions. Solving the questions let children pay their attention to exhibitions naturally and understand contents of exhibitions more. We evaluated the system in a Japanese science museum and confirmed its effectiveness.\",\n \"Title: Puppet theater system for normal-hearing and hearing-impaired people\\nYear: 2012\\n\\nAbstract: We are developing Puppet Theater system which enables both the hearing impaired and the normal hearing to enjoy a puppet show. This system projects puppet's lines in balloon on the background. In addition, the system has a function that presents branches of the story to audience and allows them to select. We performed the system to elementary school pupils with hearing impairment and found that the pupils enjoyed it. Effects of the function were investigated with questionnaire. This paper describes the function and the result of questionnaire.\",\n \"Title: Big Fat Wand: A Pointing Device for Open Space Edutainment\\nYear: 2009\\n\\nAbstract: This paper presents principles, functions, and experiments of a new edutainment tool: Big Fat Wand (BFW). BFW is developed from a conventional laser show device, however, it is modified to a small enough one to be used at an open apace. BFW is connected to a laptop PC, which provides character, symbol images, and/or animations. From experimental results, we conclude that BFW is a good gear for a facilitator to educate and educate hearing-impaired students.\",\n \"Title: Towards the Integration of Physical and Virtual Worlds for Supporting Group Learning\\nYear: 2000\\n\\nAbstract: In this paper, we describe a system that integrates physical worlds (physical cities) and virtual worlds (digital cities), and its applications to supporting group learning. We have so far constructed several systems for supporting collaborative learning. One of the aims of CSCL (Computer-Supported Collaborative Learning) is to promote mutual learning through interactions and discussions among learners. Our previous experiments, however, have shown that these systems may not be so effective for supporting interactions and discussions at times. In order to enhance interactions further, a system should support externalization of each learner in an easily recognizable manner. Through such externalization, learners can actively collaborate or conflict with each other through discussions. The proposed system integrates a board game and a computer simulation, is used for studying urban planning and environmental problems. Each learner externalizes and represents his/her own ideas on a board game, which allows him/her to actively participate in a learning situation and to share the representations with other learners. The computer simulation calculates and visualizes the status of the city being constructed on the board game, in terms of air pollution, water pollution, etc.. Thirty fifth-grade pupils who had studied environmental problems in school participated in the experiments. The experiments showed that our system is effective for enhancing interactions, activating discussions, and raises learners' engagement.\",\n \"Title: Practice! YUBIMOJI AIUEO for Japanese Hand Language Learning\\nYear: 2004\\n\\nAbstract: In paper, we describe a PC-based Japanese hand alphabet learning system: Practice! Yubimoji AIUEO (PYA) to let ordinary elementary school pupils learn basic character expressions (AIUEO) of the Japanese hand characters (Yubimoji). PYA is a very simple system both from technical and educational points of view. Experiments in an elementary school shows that pupils have really enjoyed the system and learning, thus, we believe PYA is effective as an edutainment tool.\",\n \"Title: Visitor movement as implicit human-computer interactions in museums\\nYear: 2008\\n\\nAbstract: This paper outlines a novel location-based visitor assistant system in museums. It introduces visitor movement as a user-friendly and natural mechanism for enabling visitors. It enables visitors to explicitly or implicitly select annotation content about the exhibits and answer quizzes about their knowledge by their moving to specified spots in a museum. We operated the system at a science museum in Japan and received many positive evaluations from visitors.\",\n \"Title: KIKIWAKE: sound source separation system for children-computer interaction\\nYear: 2013\\n\\nAbstract: In general living environments, in order to separate children's voices from backgrounds noise, we developed a sound separation system by a microphone array. We created a game by use of this developed system, and conducted evaluation experiment intended for elementary school children. As a result, we confirmed this system could separate 3 voices, and the game promotes children's interest in or concerns about a microphone array in a quantitative way.\",\n \"Title: Toward an Interactive Museum Guide System with Sensing and Wireless Network Technologies\\nYear: 2002\\n\\nAbstract: In this paper, we describe an interactive guide system for kids in museums. The system uses a sensing board which can rapidly recognize types and locations of multiple objects, and creates an immersive environment by giving users visual and auditory feedback to their manipulations on the board. The purpose of the system is to attract users' interests in a real exhibition by allowing them to interact with the corresponding virtual exhibition on the board, and providing them with its information. We have evaluated the system in a museum. From the interviews and questionnaires, we have confirmed that it is easy for kids to use the system and it can raise their motivation for visiting real exhibitions.\",\n \"Title: A next-generation audio-guide system for museums \\\"soundspot\\\": an experimental study\\nYear: 2007\\n\\nAbstract: This paper proposes the SoundSpot system, a location/user-dependent audio guide system to reduce many restrictions of existing audio-based annotations. It can track the positions of visitors and then only provide sound information to the limited spots around them. We experimented it in an elementary school, where students listened to annotations played by it and their understanding was evaluated. The result of the questionnaire based survey and their answers to the quiz regarding the contents of the sounds proved that the system had the possibility to enable users to enough listen to and understand the contents.\",\n \"Title: Evaluation of the Dialogue Information Function of Interactive Puppet Theater: A Puppet-Show System for Deaf Children\\nYear: 2013\\n\\nAbstract: We have developed Interactive Puppet Theater, a puppet-show system designed for use by deaf children. For this study, we conducted evaluation experiments to determine whether Interactive Puppet Theater helps these children to have an enriched viewing experience. The evaluation results showed that Interactive Puppet Theater could be an effective way to ensure that deaf children understand the characters' dialogue as they watch the puppet-show, and that it enables them to have an enjoyable viewing experience.\",\n \"Title: Enjoyable \\\"LEGS\\\" system deepens children's learning in a zoo\\nYear: 2010\\n\\nAbstract: The authors have developed a system called Learning Evolution in a zoo with GPS equipped mobile phones (LEGS). In the LEGS system, GPS-equipped mobile phones are used to learn about animals and their bodies from the viewpoint of evolution in a zoo. This system makes use of GPS-equipped mobile phones to display appropriate content about an exhibit by acquiring and saving information about a user's current position and his/her history of past activities. We examined differences between cases where junior-high students use the proposed system and where they use exhibition panels. As a result, we have found that using the LEGS system could activate students' thinking and communication, and serve to deepen their understanding of the learning content, so that students were able to enjoy animal observations.\",\n \"Title: The sensing board enhanced by interactive sound system for collaborative work\\nYear: 2004\\n\\nAbstract: In this paper, we describe a new sensing board system enhanced with audio devices. Our previous board system provides users with common display images using tangible pieces, thus, users collaboratively work with visual and tangible information. On the other hand, the proposed system is characterized by the functionality of the direct responses of both sounds and images from the contents. Using the system, we develop three application systems with the following objectives: (1) Users enjoy interaction of sounds and images; (2) Users have high level of engagement; and (3) Users enjoy personal sounds and images. We have carried out experiments to evaluate the benefits and have found that these systems enhance user engagement, participation, and continuous operation.\",\n \"Title: A system for supporting group learning that enhances interactions\\nYear: 1999\\n\\nAbstract: In this paper, we describe and evaluate a system for supporting group learning that enhances interactions among learners. To date we have constructed several systems for supporting collaborative learning. One of the aims of CSCL is to promote mutual learning through interactions and discussions among learners. Our previous experiments, however, have shown that these systems may not be so effective for supporting interactions and discussions at times. In order to enhance interactions further, a system should support externalization of each learner in an easily recognizable manner. Through such externalization, learners can actively collaborate or conflict with each other through discussions.The proposed system integrates a board game and a computer simulation, and is used for studying urban planning and environmental problems. Each learner externalizes and represents his/her own ideas on a board game, which allows him/her to actively participate in a learning situation and to share the representations with other learners. The computer simulation helps the learners to understand the status of the town constructed on the board game.Several experiments were carried out in a public elementary school. The results show that our system is effective for enhancing interactions, discussions and learner engagement.\",\n \"Title: KEI-Time Traveler: A Virtual Time Machine with Mobile Phones for Learning Local History\\nYear: 2009\\n\\nAbstract: KEI-Time Traveler is a kind of \\\"virtual time machine\\\" that requires only commercially available mobile phones with no hardware attachment. In reality, KEI-Time Traveler presents graphical images of a past scene within a given area, viewed from the location measured using GPS and with arbitrary viewing angles. Users can explore a virtual past world using this system. A promising application of KEI-Time Traveler is edutainment. We applied it for learning activities with a group of 34 junior high school students. They virtually visited a world of 1938, when a severe landslide disaster occurred. They were able to compare conditions now and in the past directly at places with which they were familiar. The design approach and evaluation of our edutainment practice are described herein. Technically, the system uses 3D-model-based graphics that can be updated continually. From an educational perspective, students truly enjoyed the experience. It was not merely fun: our system raised their motivation to learn about disaster prevention. We confirmed the edutainment effect based on evidence: user responses and recordings of their experiences.\",\n \"Title: Evaluation of the Universal Puppet Theater Based on Inclusive Design Method\\nYear: 2012\\n\\nAbstract: In this study, we have improved the Universal Puppet Theater. Improvements have been made to branching scenes in the story. The exploratory evaluation experiment was a within-subject comparison of the existing version and improved version of the system. The subjects were 53 hearing-capable fourth-grade elementary school children. The results of analysis showed that the improved version of the system with branching function was more effective interface than the existing version.\",\n \"Title: Practice! YUBIMOJI AIUEO: An Edutainment System of Japanese Hand Alphabets for Elementary School Children\\nYear: 2007\\n\\nAbstract: Practice! YUBIMOJI AIUEO (PYA) is an edutainment system to promote basic expressions of Kana characters (AIUEO) of Japanese hand alphabets (YUBIMOJI) to ordinary children at elementary school age. In this paper, we report how PYA is good in edutainment objectives based on the series of experiments at classrooms of Sumiyoshi Elementary School, in Kobe, Japan. The results have suggested that 1) even if the users do not like personal computers, they can use PYA and keep their interests, 2) PYA users keep the understanding about the hand alphabets longer, 3) they love the puppy hints and they are affective, and 4) they can memorize the character shapes. In one sentence: to use PYA is definitive.\",\n \"Title: BESIDE: Body Experience and Sense of Immersion in Digital Paleontological Environment\\nYear: 2015\\n\\nAbstract: We are developing an immersive learning support system for a paleontological environment within a museum. The system measures the physical movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment by adapting the surroundings according to these movements. As the first stage of this project, we have developed a prototype system that allows learners to experience the paleontological environment. Here, we evaluate the operability of the system, degree of learning support, and sense of immersion for primary schoolchildren. This paper summarizes the current system and describes the evaluation results.\",\n \"Title: KIKIWAKE: participatory design of language play game for children to promote creative activitybased on recognition of japanese phonology\\nYear: 2014\\n\\nAbstract: This study proposes a system for supporting the Shotoku Taishi game, which is a language play game that uses the voice of children. The Shotoku Taishi game is a group game in which multiple people presenting a problem vocalize different words at the same time and the respondents are required to guess what the combination of the words is. The authors developed and implemented a system using a microphone array to extract the voice of a specific person presenting a problem in this game. The participants were 36 elementary school students whose native language was Japanese. The results showed that the participants were enjoying the Shotoku Taishi game and that this group activity was a creative activity that deepened their awareness of the Japanese language.\",\n \"Title: StampOn in a museum: helping children's scientific inquiry\\nYear: 2014\\n\\nAbstract: This study proposes a mobile support system \\\\\\\"Stamp-On\\\\\\\" to promote elementary school children's scientific inquiry into museum exhibits. The unique characteristic of Stamp-On is its use of a stamp-shaped interface to connect exhibits and mobile device content in an extremely simple way. In this paper, we first describe the principles and implementation of the Stamp-On system. Then, we evaluate the performance of the Stamp-On system at a various rock exhibitions. For the evaluation, 35 Japanese sixth-grade elementary school children (aged 11-12) used the Stamp-On system. We recorded the actions and utterances of one of them during their scientific inquiry process. To clarify the effectiveness of Stamp-On, we have analysed the following two factors in the scientific inquiry processes: 1) observing subjects attentively and 2) interpreting information obtained through the observation. Based on these analyses, we conclude that Stamp-On is effective to promote scientific inquiry among children.p\",\n \"Title: Immersive observation support system toward realization of \\\\\\\"interactive museum\\\\\\\": observing \\\\\\\"live\\\\\\\" extinct animals while walking in a virtual paleontological environment\\nYear: 2014\\n\\nAbstract: The authors developed a computer-animated \\\\\\\"interactive museum\\\\\\\" to improve observers' levels of interest and immersion during the exploration of virtual paleontological environments. In the system, animals on the screen move in synchronization with the observer's actions, and hence, the observer feels as though he/she has entered a real-life paleontological environment. In this paper, in order to enhance the immersive experience, we upgraded the system based on the results of past preliminary evaluation. In the upgraded system, animals on the screen animate whenever an observer walks across the screen, and the animal under observation changes in response to the observer walking backward or forward towards the screen. In this way, the observer becomes part of the virtual paleontological environment. Then, in order to verify the upgrade's effectiveness, we conducted an evaluation. The results indicated that the upgrade of the system was effective in immersing observers because of the fidelity of the simulation and the enjoyment afforded by moving one's own body.\",\n \"Title: Discovering how other pupils think by collaborative learning in a classroom\\nYear: 2000\\n\\nAbstract: The authors have so far developed a system that supports collaborative learning and evaluated it in school education. The system integrates physical and virtual worlds to teach urban planning and environmental problems by game playing by the pupils themselves. Intensive experiments with the system have proven that it can support the externalization of learners' thinking, active participation, interactions among them, and discussions in a learning situation. The paper addresses the effects of collaborative learning, and discusses how pupils discover the way of thinking of other pupils during game play\",\n \"Title: Balancing virtual and real interactions in mobile learning\\nYear: 2011\\n\\nAbstract: KEI-Time Traveller is a kind of virtual time machine that merely requires the use of commercially available GPS phones. In reality, KEI-Time Traveller shows graphical images of a virtual past scene within a given area as viewed from the current location and with arbitrary viewing angles. Users can virtually explore the past world using this system. We applied it to junior high school students, twice. They virtually visited a world of 1938, when a severe landslide disaster occurred, but the designs of interaction with the virtual past world differed between the two fieldwork trials. By comparing the results, we discuss the design of the interaction and its effects on the fieldwork.\",\n \"Title: Science Education Enhancement within a Museum using Computer-human Interaction Technology.\\nYear: 2016\\n\\nAbstract: We are developing an immersive learning support system for paleontological environments in museums. The system measures the physical movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment by adapting the surroundings according to these movements. As the first step toward realizing an immersive learning support system for museums, Yoshida et al. developed and evaluated a prototype system. However, their system cannot learn about certain paleontological features such as the names of extinct animals and their characteristics. Therefore, we developed an improved version of this system that allows for an enriched knowledge of paleontological environments, focusing in particular on extinct animals and plants and the ecological environment. Here, we evaluate the systemâs learning assistant and immersive features insofar as they are directed toward children in primary school. This paper summarizes the current system and describes the evaluation results.\",\n \"Title: Supporting Zoo Visitors' Scientific Observations With A Mobile Guide\\nYear: 2016\\n\\nAbstract: This study proposes an observation guide to support zoo visitors' scientific observation of animals in motion by providing viewpoints through animations. One of the difficulties that visitors experience when observing animals is that they do not sufficiently understand the functions and behavior of the body parts of the animal they are seeing. The guide aims to enhance visitors' understanding by resolving this issue through the use of animations of the functions and behaviors of parts of animals' bodies. To evaluate the guide, we had kindergarteners and elementary school students use its contents on seals while observing their hind flippers, noses, and claws at the Asahiyama Zoo. Our finding was that the guide was an effective means to enhance the children's understanding of the functions and behaviors of these parts of the body.\",\n \"Title: Live Biblia: Evaluation of a Support System with a Tangible Interface for Viewing Science Museum Exhibitions.\\nYear: 2016\\n\\nAbstract: In this study, we present a museum exhibit guide system that uses a tangible user interface: Live Biblia. Based on the visitorâs learning interests, museum exhibits are sorted and mapped by the system. Thus, it is possible to create a unique viewing map for the visitor, unrestricted by the existing exhibit environment. We describe the development and evaluation of the implemented Live Biblia prototype, which provides exhibit information based on selected material objects. We conducted evaluation experiments to examine the systemâs effectiveness. The results suggest that the interface prototype using physical objects spurred participantsâ interest in paleontology and facilitated effective museum exhibit learning. Additionally, we found that presenting information in the prototype animation aroused the participantsâ motivation to learn and supported the viewing of not only the single fossil object but also the related museum exhibits.\",\n \"Title: Preparatory development of a collaborative / interactive learning game using bodily movements for deaf children.\\nYear: 2016\\n\\nAbstract: In this paper, we develop a collaborative/interactive learning game for deaf children. We developed two separate activities for the proposed game: 'jumping' and 'filling in the blanks'. These two activities are described in detail. Because deaf children tend to find it difficult to acquire voice information, we examined a system that supports the construction of an environment for deaf children in which collaborative learning is encouraged from the perspective of science education. The results of an evaluation confirm that the proposed game encourages collaborative learning among deaf children and improves their motivation to learn grammar.\",\n \"Title: Multiple-Player Full-Body Interaction Game to Enhance Young Children's Cooperation.\\nYear: 2016\\n\\nAbstract: We have developed a full-body interaction game that allows children to cooperate and interact with other children in small groups. The aim of the game developed in this study is to encourage cooperation between children. The game requires two children to jump together at the same time. In a series of experiments, we observed children using several strategies to coordinate the timing of their jumps, such as shouting to one another and watching each other. The results of a questionnaire to evaluate the proposed interactive game indicate that children strategize to cooperate with each other while enjoying the game. Therefore, the game enables children to cooperate with others using bodily movements.\",\n \"Title: Participatory Design of UKIYO-E Game for Children to Support Art Appreciation Based on Interacting with Pictures.\\nYear: 2016\\n\\nAbstract: We are developing an art-appreciation system that will provide learning information about pictures while generating interest in the pictures themselves. This system can provide learning information on pictures by talking to an artist or people portrayed in the pictures using voice recognition. Furthermore, the system operates through movement and location of the user, and it generates sensation such that the user feels he/she is in the pictures, thus actively appreciating the pictures. As the first step toward this system, we have developed a system that provides learning information to the user by actively talking using ukiyo-e. Here, we quantitatively evaluate this system for primary schoolchildren and determine whether the user is interested in the pictures while talking to the pictures using voice recognition measured by electrodermal activity. In this paper, we summarize the current system and describe two evaluation results.\",\n \"Title: Proposal for science learning materials using a \\\"VibGrip\\\".\\nYear: 2015\\n\\nAbstract: We created a new hearing device called \\\\\\\"VibGrip(VG)\\\\\\\". The name VG came from the concept of Vib(ration) Grip. The VG has 5 piezoelectric elements mounted on a small housing that make it possible to feel the vibrations of different frequency bands with each finger. As an application of this device, we have developed a system that can sense the difference in sounds made by insects. Using a combination of speakers and the VG, we expect that a person with hearing impairment will be able to sense the information from the sounds more clearly.\",\n \"Title: Experience-based learning support system to enhance child learning in a museum: touching real fossils and \\\"experiencing\\\" paleontological environment.\\nYear: 2015\\n\\nAbstract: This paper presents a support system to assist learning within museums. Museums represent important places of scientific learning for children. However, because the main learning method in museums is the study of displayed specimens and their corresponding explanations, the motivation of a child to learn is low. Hence, we are developing an experience-based learning support system such as entertainment that will enable learners to enhance their motivation to learn in any museum. We develop two systems to realize experience-based entertainment. One is \\\\\\\"Live Biblia,\\\\\\\" which is a digital installed book system that uses real fossil. Another is the immersive learning system we called \\\\\\\"Body Experience and Sense of Immersion in Digital paleontological Environment\\\\\\\" or \\\\\\\"BESIDE,\\\\\\\" which enables learners to explore a virtual paleontological environment. In this paper, we present a summary of the current system of Live Biblia and BESIDE.\",\n \"Title: A Full-Body Interaction Game for Children with Hearing Disabilities to Gain the Immersive Experience in a Puppet Show.\\nYear: 2015\\n\\nAbstract: In this study, we developed a full-body interaction game that assists children with hearing disabilities in experiencing a puppet show by immersing in it. The full-body interaction game presents a type of puppet show that offers opportunities for the audience to interact with the drama. It is designed so that children with hearing disabilities can participate through known communicative movements; it allows children to easily grasp how their movements affect the progress of the story. The experiment results indicate that participating children enjoy the interaction game, and that the system allows the world of the story in the puppet show seem more real.\",\n \"Title: Integration Of Ultrasonic Sensors And Kinect Sensors For People Distinction And 3d Localization\\nYear: 2013\\n\\nAbstract: The method proposed here for 3D position measurement and identification of individuals by integrating ultrasonic and Kinect sensors uses ultrasonic transmitter tags with unique identifiers. Ultrasonic sensors measure the 3D positions of and identify tagged individuals, but cannot make measurements if there are no receivers in the direction of ultrasonic waves from transmitters. Kinect sensors measure 3D positions of individuals and track them with OpenNI, but Kinect sensors cannot make measurements if occlusion occurs due to the overlapping of individuals. Evaluation results show that the method proposed here is more robust than methods only using either ultrasonic or Kinect sensors.\",\n \"Title: Depth information based separation of moving speakers' voices from mixed recordings.\\nYear: 2016\\n\\nAbstract: This paper proposes a method for separating the voice of a signal person from the voices of multiple speakersu0027 in a mixed recording. When the sounds of multiple speakers are present when a voice recognition system is operating, the quality of speech recognition decreases. The proposed method separates the sound of multiple speakers using signal processing techniques and a microphone array. The position of the speaker is also required; however, the microphone array cannot be used for this purpose. Consequently, the position of the speaker was determined using the Kinect V2 depth image sensor. An experiment was performed to separate a signal voice from many voices. The results of the experiment show that, it is possible to separate two voices using the proposed technique.\",\n \"Title: Interactive Objet D'Art Based On Iot Technology\\nYear: 2016\\n\\nAbstract: Applying Internet of Things (IoT) technology to art can open up new possibilities for the interaction between systems and humans. In this study, interaction between appreciators and fine art was realized using IoT technology. Raspberry Pi, a low-cost credit card-sized single-board computer, was used to enable appreciators to change animations displayed onscreen in fine art using physical movement. This paper reports on our realization of interaction between appreciators and objet d'art using IoT technology and describes a demonstration conducted via an exhibition that was open to the public.\",\n \"Title: Belong: Body Experienced Learning Support System Based On Gesture Recognition Enhancing The Sense Of Immersion In A Dinosaurian Environment\\nYear: 2017\\n\\nAbstract: As the first step toward realizing an immersive learning support system for museums, Yoshida et al. developed and evaluated a prototype system. However, this system was problematic in that it could only be operated by using simple body movements. Moreover, the other problem was that learning about paleontology itself cannot be performed only by learning about a paleontological environment. Therefore, we developed an immersive learning support system \\\"BELONG\\\" as an upgraded version of the above-mentioned system. Using a recognizer capable of gesture recognition, the system can be operated using complicated body movements. The improved system enables learners to enhance their sense of immersion in a paleontological environment and learn about the fossil itself and its paleontology. This paper summarizes the prototype of \\\"BELONG\\\" and describes the experiments that were performed to evaluate its ability to achieve learning support and immersion.\",\n \"Title: Preliminary Evaluation Of A System For Helping Children Observe The Anatomies And Behaviors Of Animals In A Zoo\\nYear: 2017\\n\\nAbstract: In order to support children's scientific observation in zoos, we developed a system for helping children to observe the anatomies and behaviors of animals. This system provides viewpoints for observation via animations. Observing the anatomies and behaviors of animals is related to scientific observation. As a case study, we developed a system for learning about penguins and held a workshop at Kobe Municipal Oji Zoo. At the workshop, 19 elementary students used the system and observed how penguins swim and walk along with the skeletons of their legs and flippers. We examined the evaluations of children's enjoyment of this system. They responded to five items on their feelings about using this system on five-point scales. The number of affirmative responses was found to be more in number than neutral or negative responses. Children were able to enjoy using this system for observing the anatomies and behaviors of animals in a zoo.\",\n \"Title: Development Of An Automatic Location-Determining Function For Balloon-Type Dialogue In A Puppet Show System For The Hearing Impaired\\nYear: 2017\\n\\nAbstract: People with hearing impairments have a tendency to experience difficulties in obtaining audio information. They have difficult to watch puppet shows. In this study, we have undertaken the development of a dialogue presentation function in a puppet show system for the hearing impaired. The dialogue presentation function that was developed is an automatic location-determination system for balloon-type dialogue. The balloon-type dialogue turns the lines of dialogue into text and displays it as balloons in the background animation of the puppet show. This function automatically places the balloon-type dialogue in the vicinity of the locations of the puppets. In the evaluation test, 24 college students with a hearing impairment were used as participants, and a comparison was made between a system that implemented the automatic location-determination function for balloon-type dialogue and a system that did not implement said function. These results indicate the effectiveness of the location tracking function for balloon-type dialogue as a means for ensuring access to audio information in puppet shows.\",\n \"Title: Development Of Experiential Learning System Based On The Connection Between Object Models And Their Digital Contents Collaboration Between Tangible Interface And Computer Interaction\\nYear: 2017\\n\\nAbstract: Experiential learning is effective for educating children. However, there are many issues associated with this technique. In this study, we describe the development of a learning support system using which learners can experience touching and viewing in real and virtual environments. In the first stage of our study, we develop a larval mimesis experience system consisting of a Kinect sensor, larval models, and load sensors. The system is controlled using Arduino. Using the proposed system, learners can exercise full body interaction in the virtual environment; specifically, they can experience how larva models are observed in the real environment. The operation of this system was experimentally evaluated by learners from a primary school. The results indicate that the system is suitable for the use of children. In addition, the effectiveness of the learning support was evaluated by using a questionnaire. This paper summarizes the development of the proposed system and describes the evaluation results.\",\n \"Title: Development Of Gesture Recognition Sub-System For Belong Increasing The Sense Of Immersion For Dinosaurian Environment Learning Support System\\nYear: 2017\\n\\nAbstract: We are developing an immersive learning support system for paleontological environments in museums. The system measures the body movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment. Conventional systems are only able to recognize simple body movements, which is insufficient to completely immerse learners in the paleontological environment. On the other hand, when they need to perform complicated body movements, learners move their bodies eagerly while thinking. This emphasizes the importance of developing a sub-system capable of recognizing complicated body movements. In this paper, we describe a sub-system developed to recognize the body movement of the most important learner in the immersive learning support system.\",\n \"Title: Satoyama: Time-Limited Decision Game For Students To Learn Hundreds Years Forestry Management\\nYear: 2017\\n\\nAbstract: Global environmental problems continue to worsen. In this situation, it is important to understand and experience changes in the natural environment in realistic ways. However, it was difficult to experience these changes in real time because they happen over large time scales. To overcome this problem, the authors developed a game-like learning tool that enables players to learn about vegetation succession. This game is Windows-based and enables players to simulate the conservation of SATOYAMA, rural natural areas. The player selects the actions within a designated time and the vegetation succession of the SATOYAMA changes according to that action. At the end of this game, the score is based on the SATOYAMA conserved by the player. Thirty-seven students participated in this experiment whose result suggested that this game would enable children to develop an interest in vegetation succession and motivate them to learn about it.\",\n \"Title: Laughing voice recognition using periodic waveforms and voice-likeness features.\\nYear: 2016\\n\\nAbstract: With a goal of advancing human-machine collaboration, we propose a method to recognize a laughing voice. A previous study that proposed a laughing voice recognition method was based on the periodic waveform feature of the laughing voice. However, identifying laughing voices from waveforms is problematic, because this can result in false positive results. To overcome this problem, we propose a laughing voice recognition method that incorporates a voice-likeness feature. In addition, we make a laughing voice recognition system using our proposed method. To confirm the efficacy of the laughing voice recognition method, we evaluated this system. In our evaluation, we were able to correctly recognize laughing voice at a high success rate of 97%. In comparison with the previous study, the recognition rate improved by 18%; therefore, our proposed method can be considered an effective in recognizing laughing voice.\",\n \"Title: Children'S Evaluations Of A System Supporting Observation Of Anatomies And Behaviors Of Animals In Zoos\\nYear: 2017\\n\\nAbstract: In order to support children's observation and taxonomic judgment in zoos, we developed a pilot system to provide animated visualizations of the anatomy and behavior of penguins. Nineteen children observed penguins and a penguin skeleton. We examined the children's evaluations of this system by conducting interviews. Most evaluations were positive; for example, the system helped children understand penguin anatomy and behavior, which they could not observe just by watching live penguins. From children's evaluations, the system was found to be useful.\",\n \"Title: Novel Application Of Spherical Microphone Array Sensor With Three-Dimensional Directivity For Home And Office Environments\\nYear: 2015\\n\\nAbstract: Interest in sound interfaces is increasing because such interfaces do not need advanced knowledge about particular devices, nor do they require physical operation. However, such interfaces are difficult to use because the general living environment often contains background noise. In order to solve this problem, sound separation systems that use a microphone array sensor have been proposed. In previous work, this microphone array sensor was a small system that considered only two-dimensional (2-D) directivity control. In this paper, we present the design of a spherical microphone array sensor with 3D directivity. This 3-D directivity property is confirmed via an experimental evaluation.\",\n \"Title: Novel application of a range image sensor to eye gaze estimation by using the relationship between face and eye directions\\nYear: 2015\\n\\nAbstract: In this study, we estimate gaze direction using the relationship between the face and eyes. The face and eyes are divided laterally and in lengthwise direction. We set up an object laterally and in lengthwise direction and measured the face angle using a Kinect sensor, which is range image sensor, when gazing at an object. The angle of the eyes is fixed at the angle of the object and grasp of the relationship between face and eyes. We calculate the gaze direction using the relation between the face and eyes. Then, the results of present experiment, if based on relationship between face and eyes, has been shown to be effective though the results of the experiment.\",\n \"Title: Electrodermal activity based study on the relationship between visual attention and eye blink\\nYear: 2015\\n\\nAbstract: In this paper, the relationship between visual attention and eye blinking is described. In our experiment, we observed blinking when a subject performed a task. We determined that the subjectu0027s visual attention functions during the task by electrodermal activity. Experimental results showed that blink rate decreased when the subjectu0027s visual attention was engaged. On the other hand, blink rate increased when the subjectu0027s visual attention shifted from attentive to inattentive. These findings enable a more objective evaluation of the relationship between visual attention and blinking when determining by electrodermal activity whether visual attention is engaged.\",\n \"Title: Novel application of Kinect sensor to support immersive learning within museum for children\\nYear: 2015\\n\\nAbstract: This paper presents a system to support learning within museum for children as a novel application of Kinect based human sensing system. The system measures the physical movement of the learner using a Kinect sensor, and provides a sense of immersion in the paleontological environment by adapting the surroundings according to these movements. As the first stage of this project, we have developed a prototype system that allows learners to experience the paleontological environment. Here, we evaluated the performance of the sensor of BESIDE in order to confirm whether or not this system can put into practice BESIDE at the museum. This paper summarizes the current system and describes the evaluation results.\",\n \"Title: Implementation and Evaluation of a Wide-Range Human-Sensing System Based on Cooperating Multiple Range Image Sensors.\\nYear: 2019\\n\\nAbstract: A museum is an important place for science education for children. The learning method in the museum is reading exhibits and explanations. Museums are investing efforts to quantify interests using questionnaires and sensors to improve their exhibitions and explanations. Therefore, even in places where many people gather, such as in museums, it is necessary to quantify people's interest by sensing behavior of multiple people. However, this has not yet been realized. We aim to quantify the interest by sensing a wide range of human behavior for multiple people by coordinating multiple noncontact sensors. When coordinating multiple sensors, the coordinates and the time of each sensor differ. To solve these problems, coordinates were transformed using a simultaneous transformation matrix and time synchronization was performed using unified time. The effectiveness of this proposal was verified through experimental evaluation. Furthermore, we evaluated the actual museum content. In this paper, we describe the proposed method and the results of the evaluation experiment.\",\n \"Title: Implementation And Evaluation Of Accessible Caption System In Universal Puppetry: A Case Study On Hearing Impaired Children At The Elementary School Of Deaf\\nYear: 2017\\n\\nAbstract: This study tested and evaluated two functions developed as a part of the balloon-type caption display system in a universal puppetry. Two functions are the automatic location-determining function and the emotional expression function. The automatic location-determining function is feature that make captions positioned according to the positions in which the puppets move. And emotional expression function changes the shape of balloons that represents emotions such as joy, anger, sadness, and pleasure. We conducted the evaluation experiment. Participants are fifteen students with hearing impairments from the elementary school of deaf. The result shows the effectiveness of the automatic location-determining function and the emotional expression function as a means to compensate for vocal information in puppetry for hearing impaired children.\",\n \"Title: Novel application of 3D range image sensor for estimation of interests based on fixation time of face orientation\\nYear: 2017\\n\\nAbstract: In this paper, we describe the relationship between the presence or absence of interest and the fixation time of face orientation. There is a conventional method of measuring the fixation time of line-of-sight orientation to prevent accidents due to carelessness. In addition, studies are being performed on the estimation of the relationship between face orientation and line-of-sight orientation. However, even if face and line-of-sight remain, it has not been confirmed whether people are interested. Therefore, we conducted experiments to investigate the relationship between the presence or absence of interest and the fixation time of face orientation. We simultaneously measured the change in interest and face orientation with time as subjects watched two movies. As a result, it was suggested that face orientation remained longer for an object of interest.\",\n \"Title: Accuracy evaluation of hand motion measurement using 3D range image sensor\\nYear: 2017\\n\\nAbstract: Techniques capable of measuring hand motion are expected to be applied in various situations. Examples are the practice support systems used in activities such as sport and dance, for instance, the system employed in baseball pitching form analysis. This analysis evaluates the state of the throwing form numerically and visually by measuring the velocity and trajectory of the hand. This requires measurement of the hand by a sensor and is accomplished by using a motion capture system as the method for measuring hand motion with high accuracy. However, it is time consuming to prepare the system. Therefore, a 3D range image sensor, which is inexpensive and easy to prepare, is proposed. However, as the actual measurement accuracy of this sensor is unknown, it was evaluated by calculating the error with the measured value of motion capture as the true value. In this research, we calculated the error between the 3D coordinates and velocity to evaluate the error. As a result, the effectiveness of the measurement accuracy of the hand motion by the 3D range image sensor was confirmed. The results suggest that the 3D range image sensor can be used in various situations involving human activity.\",\n \"Title: Novel application of microphone array sensor for children's language learning support — Intelligent Interactive Design using voice separation and recognition system —\\nYear: 2015\\n\\nAbstract: Development of a robust and precise voice interface could accelerate the realization of a learning support system that utilizes voice. In our research, this objective is called Intelligent Interactive Design of learning support. In order to realize Intelligent Interactive Design, we propose a “voice separation and recognition system” that aims at clear voice separation for robust voice recognition by voice recognition systems. The results of experiments conducted indicate that our Intelligent Interactive Design has a correct voice recognition rate above 70%. The results are highly satisfactory and indicate that Intelligent Interactive Design can be realized via our proposed system in the near future.\",\n \"Title: Novel Application of 3D Range Image Sensor to Caloric Expenditure Estimation based on Human Body Measurement\\nYear: 2018\\n\\nAbstract: The number of diabetic patients are increasing worldwide. Increasing calorie expenditure is one of the methods to prevent diabetes. Measuring the current calorie expenditure can improve awareness in daily life and help increase calorie expenditure. Conventional research has estimated calorie expenditure using an acceleration sensor. However, in contact sensors such as acceleration sensors, the estimation accuracy changes with the mounting position. Therefore, we aim to estimate calorie expenditure using non-contact sensors that do not need to be worn by the user. In this study, we conducted experiments to evaluate the effectiveness of estimating calorie expenditure using a 3D range image sensor, which is a non-contact sensor. The effectiveness of the proposed method was verified by the results of the evaluation.\",\n \"Title: EDA Sensor-based Evaluation of a Vegetation Succession Learning System\\nYear: 2018\\n\\nAbstract: There are many forest problems that need to be solved to move toward a sustainable society; therefore, educating people, especially children, about forest problems is very important. Although schools conventionally educate children through textbooks, children are not expected to learn about forest problems actively from only textbooks. Therefore, this study develops game-type learning material that enables students learn complex mechanisms of vegetation succession and the actual state of succession, while taking interest in forest problems, by performing forest management themselves. For evaluation of the system, we measure the electrodermal activity (EDA) because using a conventional questionnaire can only qualitatively evaluate whether learning using the system is more interesting than when using text. EDA sensors are used to measure physiological response of participants reading texts and those using the system; the interest when using the system is evaluated quantitatively. The experiment shows that the change of EDA increases when using the system, which suggests that using the system is more interesting and can be better for learning than reading text.\",\n \"Title: Application of 3D Range Image Sensor to Body Movement Detection : Supporting Children’s Collaborative Learning in Museums\\nYear: 2018\\n\\nAbstract: This paper presents a collaborative learning system to support the learning experience of children in museums. The proposed system uses the Kinect Sensor for human sensing tasks required for delivering an interactive learning experience. The study recognizes that museums are an important source of scientific knowledge as they facilitate experiential and conversational learning. However, the main learning method in museums is passive-observing exhibits and reading explanations on text panels. Thus, few opportunities exist for children to discuss the experience and engage in conversations, thereby limiting the learning experience for children. Therefore, we developed a Kinect sensor based collaborative immersive learning support system for a museum that enables children to learn through body movements and conversation. In addition, we developed interactive content that can be manipulated by children using body movements. In this manuscript, we describe the outline of the system under development. In addition, we demonstrate using experiments that the Kinect sensor can be applied to accurately recognize the body movement of multiple users; this can be regarded as the first step towards realizing a cooperative learning support system for museums.\",\n \"Title: Effectiveness of Multisensory Methods in Learning Onomatopoeia for the Hearing-Impaired.\\nYear: 2018\\n\\nAbstract: We examined the effectiveness of multisensory methods in learning animal sounds and the onomatopoeia that describe them. Hearing-impaired individuals find it difficult to learn onomatopoeia because they have limited or no access to auditory information. To address this problem, we developed a device that converts audio information into vibrations, and attempted to broaden the experience of sound by using multisensory methods to stimulate the senses of sight, hearing, and touch. In the rhythm discrimination test using the device, the hearing-impaired group showed better performance with vibration added to the audio information than without vibration. In addition, we designed a science lesson to help hearing-impaired individuals learn cicada songs. This lesson used multiple media including text, images, sounds, sound waveforms, onomatopoeia, and vibrations. The evaluation results showed a significant difference between the students who were able to distinguish the vibrations and those who could not. The former reported that they found the lesson enjoyable and that it was a useful way to learn science.\",\n \"Title: Color Held Illumination Map Estimation using GAN for Low-light Image Enhancement\\nYear: 2022\\n\\nAbstract: Recently, museum learning has attracted considerable attention. Guide robots that detect exhibits are being used to enhance learning effects. However, detecting exhibits in the dark areas of the museum is difficult. Therefore, it is necessary to enhance low-light images. In this study, we present an image enhancement method, color held illumination map estimation (CHIME) using generative adversari...\",\n \"Title: Playing with invisible animals: An interactive system of floor-projected footprints to encourage children’s imagination\\nYear: 2022\\n\\nAbstract: Playing is essential for a child’s development, and it has various positive effects. In particular, playing with toys enhances children’s imagination. In recent years, children have been tending to play with smart toys equipped with built-in computers, which present various advantages that leverage their digital characteristics. For example, smart toys can provide augmented reality functionalities through which digital information can be added to physical reality. These characteristics offer an important benefit of stimulating the interest and presence of children. However, wearable devices may be required to realize this. Wearable devices are ineffective when people do not own or cannot wear them. Therefore, we developed a system that stimulates the imagination and interest of children in playing without any wearable devices. Our system projects animal footprints onto the floor, encouraging children to play with invisible animals based on their imagination from the footprints. The footprints respond to the children’s movements. To evaluate the developed system, we conducted several experiments with children. First, we investigated the fundamental effects of the system on elementary school students. Then, we investigated the different effects of various interactions. Our experimental results showed that the developed system encourages the imagination of children while playing.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":87,"string":"87"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":271,"string":"271"}}},{"rowIdx":272,"cells":{"question_id":{"kind":"string","value":"Javier Aracil"},"question":{"kind":"string","value":"Generate an abstract for the title \"High-speed TCP flow record extraction using GPUs\" using the following items: Traffic analysis, capacity planning, quality of service, security reinforcement, flow extraction."},"answer":{"kind":"string","value":"Traffic analysis is an essential part of capacity planning, quality of service assurance, and reinforcement of security in current telecommunication networks. Traffic volume increases with network speed and the analysis of large traffic traces is computationally intensive. The paper presents, for the first time ever, a flow extraction software that allows to obtain complex TCP-aware flow records at 4.4 millions of packets per second in a single GPU. Such TCP flow records include number of retransmissions and duplicates per flow, whose calculation is very challenging to obtain at high-speed. Our software significantly increases the processing performance of the recently proposed high-speed sniffers based on commodity hardware and demonstrates the advantages of applying massively parallel processing devices for traffic analysis."},"correct_answer":{"kind":"string","value":"Traffic analysis is an essential part of capacity planning, quality of service assurance, and reinforcement of security in current telecommunication networks. Traffic volume increases with network speed and the analysis of large traffic traces is computationally intensive. The paper presents, for the first time ever, a flow extraction software that allows to obtain complex TCP-aware flow records at 4.4 millions of packets per second in a single GPU. Such TCP flow records include number of retransmissions and duplicates per flow, whose calculation is very challenging to obtain at high-speed. Our software significantly increases the processing performance of the recently proposed high-speed sniffers based on commodity hardware and demonstrates the advantages of applying massively parallel processing devices for traffic analysis."},"documents":{"kind":"list like","value":["Title: Brief Hopf bifurcation in indirect field-oriented control of induction motors\nYear: 2002\n\nAbstract: The appearance of self-sustained oscillations in high performance AC drives, and in particular, in induction motors whose speed is regulated with the industry standard field-oriented control, is a well-documented but little understood phenomenon. It is well known that the oscillations may be quenched by returning the outer-loop PI speed control, but no precise rules to carry out this task, which may be time consuming, are known. In this paper, we show that these oscillations may arise due to the existence of Hopf bifurcations. Some simple rules for selecting the gains of the PI controller are obtained as a result of our analysis.","Title: Performance analysis of asynchronous best-effort traffic coexisting with TDM reservations in polymorphous OBS networks\nYear: 2009\n\nAbstract: The in-advance reservation of bandwidth capacity philosophy of Optical Burst Switching architectures via Burst-Control Packets\n brings high flexibility in the separation of network resources for services with different quality-of-service requirements.\n In this light, real-time applications can periodically be guaranteed a certain amount of bandwidth reservation for the transmission\n of traffic with Constant Bit Rate requirements (for instance IP television, VoIP, etc), whilst the remaining capacity may\n be used for transmission of best-effort traffic of the so-called elastic applications (e-mailing, web browsing, etc). The\n Polymorphous, Agile and Transparent Optical Networks (PATON) architecture (Qiao et al. IEEE Commu Mag 44(12):104–114 2006)\n proposes periodic reservation of time-slots over one or several wavelengths of an optical fibre, yet remaining gaps in between\n them for transmission of best-effort traffic. This work presents a novel analysis of the performance perceived by best-effort\n traffic which are given full access to optical switching only during a portion of the total time. The following analyses the\n non-blocking probability among best-effort data bursts that share such available gaps in between the periods of CBR traffic.\n An exact expression of the non-blocking probability is derived when a single wavelength is used for CBR traffic, along with\n a lower bound for the case when CBR traffic is transmitted using multiple wavelengths. These results can be of further interest\n in the optimal design of OBS architectures where the transmission of high-priority real-time traffic and best-effort data\n coexist over the same wavelength.","Title: Characterization of the busy-hour traffic of IP networks based on their intrinsic features\nYear: 2011\n\nAbstract: Internet traffic measurements collected during the busy hour constitute a key tool to evaluate the operation of networks under the heaviest-load case scenarios, and further provide a means to network dimensioning and capacity planning. In this light, this study provides a throughout analysis of the busy-hour traffic measurements of an extensive set of universities, regional networks, and Internet exchange points collected from the Spanish Research and Education Network, RedIRIS. After showing that the traffic volumes observed in the busy hour over time can be modeled by a white Gaussian process, this work takes one step further and examines the influence of the networks' intrinsic features, mainly population size and access link capacity, on the busy-hour traffic. Well-known statistical methodologies, such as ANOVA and ANCOVA, show that the network size in terms of number of users justifies most of the busy-hour traffic information. We further provide a linear-regression model that adjusts the amount of traffic that each network user contributes to the busy-hour traffic mean values, with a direct application to the problem of link capacity planning of IP networks.","Title: Is multilayer networking feasible?\nYear: 2009\n\nAbstract: IP traffic has been growing every year, bringing the need for deploying an IP backbone interconnected by links provided by the transport network. Thus, network operators have had traditionally divided their core network in two, the IP network and the transport network. Network planning and engineering tasks have been performed independently in both domains. Traditionally, the transport network has been quite inflexible, and changes have often required a long time to occur. However, recent developments in the control plane allow flexibility in the transport network, making it possible to set up and tear down circuits on demand. In this light, multilayer traffic engineering has been proposed to jointly manage both IP and transport layers, with the aim of optimizing the use of resources. This paper aims to describe the rationale behind multilayer traffic engineering, demonstrate its feasibility and quantify its advantages in terms of cost effectiveness. Also, this work takes a look at the different choices in performing the multilayer operation, in terms of control plane implementation and equipment integration. Finally, the paper presents a report on multilayer traffic engineer experimentation which proves its feasibility and show a preliminary techno-economic case study of the multilayer operation.","Title: On the Early Release of Burst-Control Packets in Optical Burst-Switched Networks\nYear: 2007\n\nAbstract: In Optical Burst-Switched networks, the so-called Burst-Control Packet is sent a given offset-time ahead of the optical data burst to advertise the imminent burst arrival, and reserve a time-slot at each intermediate node to allocate it. This work proposes a methodology to estimate the number of packets to arrive in a given amount of time, in order to make it possible to send the BCP packet straightafter the first packet arrival and reduce the latency experienced during the burst-assembly process. The following studies the impact of a wrong guess in terms of over-reservation of resources and waiting-time at the assembler, providing a detailed characterisation of their probability density functions. Additionally, a case example in a scenario with non-homogeneous Poisson arrivals is analysed and it is shown how to choose the appropriate burst-assembly algorithm values to never exceed a given over-reservation amount.","Title: A Bayesian decision theory approach for the techno-economic analysis of an all-optical router\nYear: 2007\n\nAbstract: Typically, core networks are provided with both optical and electronic physical layers. However, the interaction between the two layers is at present limited, since most of the traditional transport functionalities, such as traffic engineering, switching and restoration, are carried in the IP/MPLS layer. In this light, the research community has paid little attention to the potential benefits of the interaction between layers, multilayer capabilities, on attempts to improve the Quality of Service control. This work shows when to move incoming Label Switched Paths (LSPs) between layers based on a multilayer mechanism that trades off a QoS metric, such as end-to-end delay, and techno-economic aspects. Such mechanism follows the Bayesian decision theory, and is tested with a set of representative case scenarios.","Title: Detection of traffic changes in large-scale backbone networks: The case of the Spanish academic network\nYear: 2012\n\nAbstract: Network management systems produce a huge amount of data in large-scale networks. For example, the Spanish academic network features hundreds of access and backbone links, each of which produces a link utilization time series. For the purpose of detecting relevant changes in traffic load a visual inspection of all such time series is required. As a result, the operational expenditure increases. In this paper, we present an on-line change detection algorithm to identify the relevant change points in link utilization, which are presented to the network manager through a graphical user interface. Consequently, the network manager only inspects those links that show a stationary and statistically significant change in the link load.","Title: Admission control in Flow-Aware Networking (FAN) architectures under GridFTP traffic\nYear: 2009\n\nAbstract: Computing and networking resources virtualization is the main objective of Grid services. Such a concept is already used in the context of Web-services on the Internet. In the next few years, a large number of applications belonging to various domains (biotechnology, banking, finance, car and aircraft manufacturing, nuclear energy etc.) will also benefit from Grid services. Admission control is a key functionality for Quality of Service (QoS) provision in IP networks, and more specifically for Grid services provision. Service differentiation (DS) is a widely deployed technique on the Internet. It operates at the packet level on a best-effort mode. Flow-Aware Networking (FAN) that operates at the scale of the IP flows relies on implicit flow differentiation through priority fair queuing (PFQ). It may be seen as an alternative to DS. A Grid session may be seen as a succession of parallel TCP/IP flows characterized by data transfers with much larger volume than usual TCP/IP flows. In this paper, we propose an extension of FAN for the Grid environment called Grid over FAN (GoFAN). We compare, by means of computer simulations, the efficiency of Grid over DS (GoDS) and GoFAN. Two variants of GoFAN architectures based on different fair queuing algorithms are considered. As a first step, we provide two short surveys on QoS for Grid environment and on QoS in IP networks respectively.","Title: On the processing time for detection of Skype traffic.\nYear: 2011\n\nAbstract: The last few years have witnessed VoIP applications gaining a tremendous popularity and Skype, in particular, is leading this continuous expansion. Unfortunately, Skype follows a closed source and proprietary design, and typically uses encryption mechanisms, making it very difficult to identify its presence from a traffic aggregate. Several algorithms and approaches have been proposed to perform such task with promising results in terms of accuracy. However, such approaches typically require significant computation resources and it is unlikely that they can be deployed in nowadays high-speed networks. In this light, this paper focuses on cutting the processing cost of algorithms to detect Skype traffic. We have conveniently tuned a previous well-validated algorithm and we have assessed its performance. To this end, we have used real traces from public repositories, from a Spanish 3G operator, and synthetic traces. Our results show that a single process can detect Skype traffic at 1 Gbps rates reading replayed real traces directly from a NIC. Even more, 3.7 Gbps are achieved reading from traces previously allocated in memory using a single process and 45 Gbps using 16 concurrent processes. This fact paves the way for 10 Gbps processing in commodity hardware.","Title: FPGA acceleration using high-level languages of a Monte-Carlo method for pricing complex options\nYear: 2013\n\nAbstract: In this paper we present an FPGA implementation of a Monte-Carlo method for pricing Asian options using Impulse C and floating-point arithmetic. In an Altera Stratix-V FPGA, a 149x speedup factor was obtained against an OpenMP-based solution in a 4-core Intel Core i7 processor. This speedup is comparable to that reported in the literature using a classic HDL-based methodology, but the development time is significantly reduced. Additionally, the use of a HLL-based methodology allowed us to implement a high-quality Gaussian random number generator, which produces more precise results than those obtained with the simple generators usually present in HDL-based designs.","Title: Low-Cost And High-Performance: Voip Monitoring And Full-Data Retention At Multi-Gb/S Rates Using Commodity Hardware\nYear: 2014\n\nAbstract: Voice over IP (VoIP) is increasingly replacing the old public switched telephone network (PSTN) technology. In this new scenario, there are several challenges for VoIP providers. First, VoIP requires a detailed monitoring of both users' quality of service (QoS) and experience (QoE) to a greater extent than in traditional PSTNs. Second, such a monitoring process must be able to track VoIP traffic in high-speed networks, nowadays typically of multi-Gb/s rates. Third, recent government directives require that providers retain information from their users' calls. Similarly, the convergence of data and voice services allows operators to provide new services such as full-data retention, in which users' calls can be recorded for either quality assessment (call centers, QoE) or security purposes (lawful interception). This implies a significant investment in infrastructure, especially in large-scale networks which require multiple points of measurement and redundancy. This paper proposes a novel methodology, architecture and system to fulfill such challenges, called VoIPCallMon, as well as the data structures and necessary hardware-tuning knowledge for its development. As distinguishing features, VoIPCallMon provides very high performance, being able to process VoIP traffic on-the-fly at high bitrates, novel services and significant cost reduction by using commodity hardware with minimal interference with operational VoIP networks. The performance evaluation shows that the system copes with the VoIP load of real-world operators. We further evaluated the system performance at a fully saturated 10 Gb/s link and no packet loss was reported, therefore demonstrating the potential of commodity hardware solutions. Copyright (c) 2014 John Wiley & Sons, Ltd.","Title: Codimension-Two Bifurcations In Indirect Field Oriented Control Of Induction Motor Drives\nYear: 2008\n\nAbstract: This paper provides further results on bifurcation analysis of indirect field oriented control of induction motors. Previous results presented on this subject [Bazanella & Reginatto, 2000, 2001; Gordillo et al., 2002] are summarized and extended by means of a codimension-two bifurcation analysis. It is shown that codimension-two bifurcation phenomena, such as a Bogdanov-Takens and zero-Hopf bifurcations, occur in IFOC as a result of parameter mismatch and certain setting of the proportional-integral speed controller. Conditions for the existence of such bifurcations are derived analytically, as long as possible, and bifurcation diagrams are presented with the help of simulation and numerical bifurcation analysis.","Title: Blocking models of optical burst switches with shared wavelength converters: exact formulations and analytical approximations\nYear: 2008\n\nAbstract: Loss modeling of asynchronous optical burst switches with shared wavelength converters is considered. An exact analysis based\n on continuous time Markov chains is proposed and validated by comparison with simulation for balanced and unbalanced traffic.\n A computationally efficient approximated analysis is also proposed and compared with the exact model to find applicability\n conditions. Approximate loss performance evaluation is presented for ranges of values which are not tractable either by simulation\n or exact analysis.","Title: A queueing equivalent thresholding method for thinning traffic captures\nYear: 2008\n\nAbstract: In the development of accurate capacity planning and network resource dimensioning models, network operators must handle representative information about the traffic volumes traversing its network. However, the amount of traffic measurements available over which to perform such analysis, processing and storage is overwhelming. For this reason, the research community has understood the importance of finding an effective mechanism to reduce (or subsample) such huge amount of data, with minimum loss of information. More specifically, this work considers the traffic volume traversing a given router per unit of time, which can be obtained by periodically polling the counters of the interfaces table via SNMP. We further propose a mechanism to downsample such traffic time-series using multi-resolution analysis with wavelets, and evaluate the optimal subsampling level based on comparing the queueing behavior of the subsampled and original signals at the output of a router. This mechanism is more related to network performance than conventional comparison levels, since queueing delay is a very representative QoS metric. The method presented in this paper has been applied to an extensive set of real measurements collected from RedlRIS, the Spanish National Research Network. The results show that it is possible to reduce the data to one fourth of its original size for the traffic generated by most analyzed universities, and even to one eighth for data collected from routers with more aggregated traffic, both with a high level of confidence.","Title: Evaluation of preemption probabilities in OBS networks with burst segmentation.\nYear: 2005\n\nAbstract: Preemption techniques have been recently proposed for service differentiation in Optical Burst Switching (OBS) networks. According to [1], an incoming burst with the same priority that the burst in service will preempt the wavelength if the residual length of the burst in service is smaller than the incoming burst transmission time. For a network scenario with no wavelength conversion, the preemption probability is evaluated assuming Exponential, Gaussian and Pareto-distributed burst sizes. Knowledge of the preemption dynamics at an OBS switch is a fundamental issue in performance evaluation, since the downstream switches will surely be affected. An analytical upper bound is provided, that shows that the preemption probability depends on the burst size distribution, which in turn depends on the burst assembly technique used at the network edges. On the other hand, not only truncated bursts result from preemption, as reported in other studies, but also the burst size distribution for preempting bursts is shifted to larger values.","Title: Automated Detection of Load Changes in Large-Scale Networks\nYear: 2009\n\nAbstract: This paper presents a new online algorithm for automated detection of load changes, which provides statistical evidence of stationary changes in traffic load. To this end, we perform continuous measurements of the link load, then look for clusters in the dataset and finally apply the Behrens-Fisher hypothesis testing methodology. The algorithm serves to identify which links deviate from the typical load behavior. The rest of the links are considered normal and no intervention of the network manager is required. Due to the automated selection of abnormal links, the Operations Expenditure (OPEX) is reduced. The algorithm has been applied to a set of links in the Spanish National Research and Education Network (RedIRIS) showing good results.","Title: Performance Issues in Optical Burst/Packet Switching\nYear: 2009\n\nAbstract: This chapter summarises the activities on optical packet switching (OPS) and optical burst switching (OBS) carried out by the COST 291 partners in the last 4 years. It consists of an introduction, five sections with contributions on five different specific topics, and a final section dedicated to the conclusions. Each section contains an introductive state-of-the-art description of the specific topic and at least one contribution on that topic. The conclusions give some points on the current situation of the OPS/OBS paradigms.","Title: A Bayesian decision theory approach for the techno-economic analysis of an all-optical router (extended version)\nYear: 2008\n\nAbstract: Typically, core networks are provided with both optical and electronic physical layers. However, the interaction between the two layers is at present limited, since most of the traditional transport functionalities, such as traffic engineering, switching and restoration, are carried in the IP/MPLS layer. In the light of this, the research community has paid little attention to the potential benefits of the interaction between layers, multilayer capabilities, on attempts to improve quality of service control. This paper shows when to move incoming label switched paths (LSPs) between layers based on a multilayer mechanism that trades off a QoS metric, such as end-to-end delay, and techno-economic aspects. Such a mechanism follows the Bayesian decision theory, and is tested with a set of representative case scenarios.","Title: On the blocking time distribution of core OBS switches\nYear: 2009\n\nAbstract: Given the bufferless nature of Optical Burst- Switched networks, data bursts are either transmitted or dropped; the latter\n typically occurs when all the wavelengths of a given output port are occupied. Clearly, the amount of time during which a\n given output port is blocked and cannot schedule incoming data bursts is a key performance measure of OBS networks. This work\n shows that, under Poissonian burst arrivals, the blocking time distribution of a given output port in an OBS node approaches\n the exponential distribution as the number of wavelengths increases. It is further shown that this behavior remains regardless\n of the size distribution of incoming bursts, and therefore, regardless of the burst-assembly algorithms employed at the border\n nodes. Finally, this result is also applied to the characterization of the amount of overspill traffic, that is, the number\n of bursts that arrive within a blocked period, and therefore must be either dropped or diverted over alternative routes.","Title: Reliable Network Management Tool through Internet\nYear: 1999\n\nAbstract: This paper presents a number of issues which are relevant to the development of network management tools based on Web interfaces. Specifically, the following technologies for the network management console a re evaluated: HTML, HTML/Java and Tcl/Tk. The pros and cons of the abovementioned technologies are discussed in terms of reliability, probe/console transmision delay, CPU use, data processing and alarm reception capabilities. To do so, we analyze the implementation issues of a novel network management tool, PROMIS, which performs traffic monitoring functions with information collected from a number of network probes.","Title: On the impact of packet sampling on Skype traffic classification.\nYear: 2013\n\nAbstract: Nowadays, traffic classification technology addresses the exciting challenge of dealing with ever-increasing network speeds, which implies more computational load especially when on-line classification is required, but avoiding to reduce classification accuracy. However, while the research community has proposed mechanisms to reduce load, such as packet sampling, the impact of these mechanisms on traffic classification has been only marginally studied. This paper addresses such study focusing on Skype application given its tremendous popularity and continuous expansion. Skype, unfortunately, is based on a proprietary design, and typically uses encryption mechanisms, making the study of statistical traffic characteristics and the use of Machine Learning techniques the only possible solution. Consequently, we have studied Skypeness, an open-source system that allows detecting Skype at multi-10Gb/s rates applying such statistical principles. We have assessed its performance applying different packet sampling rates and policies concluding that classification accuracy is significantly degraded when packet sampling is applied. Nevertheless, we propose a simple modification in Skypeness that lessens such degradation. This consists in scaling the measured packet interarrivals used to classify according to the sampling rate, which has resulted in a significant gain.","Title: Discrete-time heavy-tailed chains, and their properties in modeling network traffic\nYear: 2007\n\nAbstract: The particular statistical properties found in network measurements, namely self-similarity and long-range dependence, cannot be ignored in modeling network and Internet traffic. Thus, despite their mathematical tractability, traditional Markov models are not appropriate for this purpose, since their memoryless nature contradicts the burstiness of transmitted packets. However, it is desirable to find a similarly tractable model which is, at the same time, rigorous at capturing the features of network traffic. This work presents discrete-time heavy-tailed chains, a tractable approach to characterize network traffic as a superposition of discrete-time “on/off” sources. This is a particular case of the generic “on/off” heavy-tailed model, thus shows the same statistical features as the former, particularly self-similarity and long-range dependence, when the number of aggregated sources approaches infinity. The model is then applicable to characterize a number of discrete-time communication systems, for instance, ATM and optical packet switching, to further derive meaningful performance metrics such as average burst duration and the number of active sources in a random instant.","Title: An information model for the management of Optical Burst Switched networks\nYear: 2007\n\nAbstract: The optical burst switching (OBS) paradigm proposes a new set of transmission protocols and network architectures that permits the high-utilization of the raw bandwidth available by dense wavelength division multiplexing at a moderate computational cost. Accordingly, it is necessary to extend the management plane of such networks to include the particular aspects of OBS, in order to guarantee the appropriate network operation. This paper analyzes the information required for the management of such OBS networks and proposes a new information model based on observed management use-cases. A simple data model is also specified to reduce the computational burden, but compliant with the modeled information.","Title: Virtualization of reconfigurable coprocessors in HPRC systems with multicore architecture\nYear: 2012\n\nAbstract: HPRC (High-Performance Reconfigurable Computing) systems include multicore processors and reconfigurable devices acting as custom coprocessors. Due to economic constraints, the number of reconfigurable devices is usually smaller than the number of processor cores, thus preventing that a 1:1 mapping between cores and coprocessors could be achieved. This paper presents a solution to this problem, based on the virtualization of reconfigurable coprocessors. A Virtual Coprocessor Monitor (VCM) has been devised for the XtremeData XD2000i In-Socket Accelerator, and a thread-safe API is available for user applications to communicate with the VCM. Two reference applications, an IDEA cipher and an Euler CFD solver, have been implemented in order to validate the proposed architecture and execution model. Results show that the benefits arising from coprocessor virtualization outperform its overhead, specially when code has a significant software weight.","Title: A FPGA-based scalable architecture for URL legal filtering in 100GbE networks\nYear: 2012\n\nAbstract: Legal filtering is common practice in many countries to avoid access to websites with criminal or violent content. This kind of filtering is typically implemented at the edge routers of ISP's core networks, so it is mandatory to support very high bit rates. This paper proposes a hardware-software solution based on FPGAs, which scales up to 100 Gbps Ethernet. A FPGA-based PCIe board equipped with two network interfaces is used to intercept ISP traffic. The FPGA performs an initial filtering of the packets whose destination is potentially forbidden, based on a hash of the destination IP address. Filtered packets are sent to the software application, which inspects them and decides if the URL is actually forbidden or not. This two-level filtering allows for the scalability of the proposed solution to very high bit rates, not only because it simplifies FPGA design, but also because it significantly reduces software load, since potentially forbidden destinations are few. Additionally, this solution adds a minimal latency to most of the packets, and also allows for updating filtering rules without interrupting ISP traffic. The paper presents a proof-of-concept 10GbE implementation of the proposed architecture, as well as an analysis of its scalability up to 100GbE.","Title: A Tool For Solving Differential Games With Co-Evolutionary Algorithms\nYear: 1999\n\nAbstract: Game theory is concerned with optimization problems involving several players with conflicting interests. Differential games are an interesting area inside this field in which the problem is formulated by means of dynamical systems. In spite that the theoretical solution of differential games is well known, faced with large-scale, complex systems, analytical or, even, numerical methods are not usually suitable. Genetic algorithms appear to be useful for solving such problems when dealing with nonlinear, large-scale systems. This paper shows how co-evolutionary algorithms can be applied to solve differential games and presents a computer tool to formulate and solve these problems. The differential equations which define the system under study are written in Vensim, a visual modeling tool. The usefulness of the presented tool is shown by means of two examples.","Title: Packet Video Broadcasting with General-Purpose Operating Systems in an Ethernet\nYear: 2004\n\nAbstract: Video transmission with general-purpose PCs poses a number of requirements that radically differ from those of high-end dedicated video servers. We analyze the scenario of an Ethernet local area network in which a number of PCs are transmitting video streams, while other TCP/IP applications are also running concurrently. Our findings show that since the operating system clock resolution cannot cope with the transmission timing requirements the following holds: if the video transmission is performed with exact timing accuracy to maintain a constant rate then CPU load grows to 100%, thus blocking the PC for other user applications; on the other hand, if transmission is performed in a bursty manner, i.e. with sleep system calls, then CPU load decreases dramatically but the increased burstiness of the video stream has a negative impact on network performance (for example, capture effect in the Ethernet). Furthermore, the impact of video transmission over the rest of TCP/IP applications running on the same network depends heavily on the packet size. We provide an integrated analysis of operating system and network parameters to achieve video broadcasting while preserving timing requirements and minimizing the impact on other applications.","Title: PROMIS: A Reliable Real-Time Network Management Tool for Wide Area Networks\nYear: 1998\n\nAbstract: This paper presents the PROMIS tool, new network management tool based on a distributed architecture of traffic probes. PROMIS allows authorized users to monitor traffic from any WAN segment using a WWW console or a Tcl/Tk graphic interface. In contrast to current network monitoring platforms based in SNMP (Simple Network Management Protocol) or RMON (Remote network MONitor), PROMIS is based on an optimized software architecture that usesa reliable transport protocol (TCP) to provide lossless transmision of monitoring information, thus allowing for real-time monitoring irrespective of network load.","Title: Wire-speed statistical classification of network traffic on commodity hardware\nYear: 2012\n\nAbstract: In this paper we present a software-based traffic classification engine running on commodity multi-core hardware, able to process in real-time aggregates of up to 14.2 Mpps over a single 10 Gbps interface -- i.e., the maximum possible packet rate over a 10 Gbps Ethernet links given the minimum frame size of 64 Bytes. This significant advance with respect to the current state of the art in terms of achieved classification rates are made possible by:(i) the use of an improved network driver, PacketShader, to efficiently move batches of packets from the NIC to the main CPU;(ii) the use of lightweight statistical classification techniques exploiting the size of the first few packets of every observed flow;(iii) a careful tuning of critical parameters of the hardware environment and the software application itself.","Title: Factor Analysis Of Internet Traffic Destinations From Similar Source Networks\nYear: 2012\n\nAbstract: Purpose - This study aims to assess whether similar user populations in the Internet produce similar geographical traffic destination patterns on a per-country basis.Design/methodology/approach - The authors collected a country-wide NetFlow trace, which encompasses the whole Spanish academic network. Such a trace comprises several similar campus networks in terms of population size and structure. To compare their behaviors, the authors propose a mixture model, which is primarily based on the Zipf-Mandelbrot power law to capture the heavy-tailed nature of the per-country traffic distribution. Then, factor analysis is performed to understand the relation between the response variable, number of bytes or packets per day, with dependent variables such as the source IP network, traffic direction, and country.Findings - Surprisingly, the results show that the geographical distribution is strongly dependent on the source IP network. Furthermore, even though there are thousands of users in a typical campus network, it turns out that the aggregation level which is required to observe a stable geographical pattern is even larger.Practical implications - Based on these findings, conclusions drawn for one network cannot be directly extrapolated to different ones. Therefore, ISPs' traffic measurement campaigns should include an extensive set of networks to cope with the space diversity, and also encompass a significant period of time due to the large transient time.Originality/value - Current state of the art includes some analysis of geographical patterns, but not comparisons between networks with similar populations. Such comparison can be useful for the design of content distribution networks and the cost-optimization of peering agreements.","Title: On the real impact of Path Inflation in networks under production\nYear: 2012\n\nAbstract: The research community has proved the existence and studied the root causes of Path Inflation on the Internet - end-to-end paths significantly longer than necessary. However, it has been typically ignored that the popularity of traffic destinations and, consequently, of network paths, is clearly heterogeneous - some destinations are popular while others are barely accessed. In this paper, we propose a trace-driven methodology to measure the Path Inflation accounting for the popularity of Internet destinations from a given network, thus evaluating the implications that Path Inflation exerts on real networks under production. This information is important for network operators because it allows them to objectively stand out those destinations whose connection analysis must be prioritized. The results of applying this methodology to the Spanish academic network show that the most critical regions to focus on are Spain's closest countries, which either are very popular or have large Path Inflation as a consequence of the use of transatlantic links as intermediate nodes, or both.","Title: On capacity planning for the GMPLS network control plane\nYear: 2008\n\nAbstract: This article presents capacity planning rules for the control plane of all-optical networks featuring GMPLS and RSVP-TE as\n a connection setup protocol. As per RSVP standard, a refresh message mechanism is incorporated to RSVP such that the state\n is periodically refreshed on a link per link basis. We provide analytical expressions for the bandwidth and buffer sizes to\n be provided such that no flows are torn down due to lack of refresh messages. Our findings show that small buffers (several\n KBytes) suffice to sustain the signaling load for as much as 400 RSVP flows per link, with the simplest RSVP refresh mechanism\n (neither using link bundling nor acknowledgments). On the other hand, we also find the packet drop probability per link for\n a given network topology for the case that the flow survival probability is larger than a given threshold. We provide numerical\n examples based on the COST 239 european network topology and real RSVP traffic traces from early-commercial switching equipment.","Title: High-Level Languages and Floating-Point Arithmetic for FPGA-Based CFD Simulations\nYear: 2011\n\nAbstract: Editor's note:Computational fluid dynamics is a classical problem in high-performance computing. In order to make use of an existing code base in this field, the use of high-level design tools is an imperative. The authors explore the use of the Impulse C design tools for a Navier-Stokes implementation.—George A. Constantinides (Imperial College London) and Nicola Nicolici (McMaster University)","Title: High-accuracy network monitoring using ETOMIC testbed\nYear: 2011\n\nAbstract: Obtaining an accurate picture of what is happening inside the Internet can be particularly challenging using end-to-end measurements. The ability to make high-precision timing measurements (one-way delay, interarrival times, ...) using probe packets is key to attain a clear picture of network performance. The European Traffic Observatory Measurement Infrastructure (ETOMIC) is a high-precision measurement infrastructure, distributed throughout Europe. With the ANME (Advanced Network Monitoring Equipment) boxes and their related software, ETOMIC offers users a versatile monitoring solution that performs both active and passive measurements to a very high level of precision.","Title: Analysis of the backing up fuzzy control of truck-trailers using the qualitative theory of dynamic systems.\nYear: 2001\n\nAbstract: Abstract,the vehicle position givand the trailer orientation ,","Title: An Approximation of The Dynamics of Time-Delay Systems with Implications in Simulation and Analysis\nYear: 1998\n\nAbstract: A fast convergent approximation of the dynamics of a system with time delays is proposed. Such an approximation is developed in the time-domain and has a matrix representation that is affine in the magnitude of the delay tau. This affine dependence on tau allows a subsequent analysis of the robustness of the system using LMI approaches.","Title: Measurements and Measurement Tools in OpenLab: Use Cases with Measurement Data Ontologies.\nYear: 2012\n\nAbstract: In this chapter we review the network measurement tools and instruments that are in place in the FP7 OpenLab project, which provides a set of different network testbeds. We also focus on the problem of data heterogeneity, which comes from the fact that different measurement tools will provide data in different formats and structured in different ways. Therefore, a common information model becomes necessary and the OpenLab ontology-based solution is presented. Such ontology is being standardized by an Industry Specification Group at ETSI, resulting in the first ever standard on network measurement data ontologies.","Title: Describing function method for stability analysis of PD and PI fuzzy controllers\nYear: 2004\n\nAbstract: A fuzzy logic controller saturates outside the universe of discourse region. This saturation gives rise to a universal nonlinearity for this type of controller. In this paper, the effects of this nonlinearity are analyzed for the most usual fuzzy controllers: PD and PI fuzzy controllers. It is shown that due to this saturation some pathological behaviors such as oscillations or unstable limit cycles can occur. The methodology employed in the analysis is based on the describing function, which is determined for PD and PI fuzzy controllers. One example illustrates the relevance of the proposed methodology.","Title: Bifurcation Analysis Of A Rotating Arm With Saturated Hamiltonian Control Laws\nYear: 2005\n\nAbstract: The actuator saturation effects on the global state space structure of a rotating arm with a Hamiltonian control law are studied via bifurcation analysis. In addition to other well-known codimension-two bifurcation points, some saturation-induced \"fan-like\" bifurcation points are detected. The dynamical complexity found in this seemingly simple example is remarkable.","Title: Network monitoring for energy efficiency in large-scale networks: the case of the Spanish Academic Network.\nYear: 2012\n\nAbstract: Abstract The energy consumption due to information technologies is large and there are many ongoing efforts to cut it down. Previous studies have shown that there is a significant percentage of hosts which are left switched on in office buildings at night and weekend, whose energy consumption is significant. This motivates the development of techniques that can detect switched-on hosts in a simple and scalable way. This paper proposes detection techniques based on network traffic monitoring. The results show that such techniques can effectively detect switched-on hosts in small-medium campus networks and also in large country-wide networks that serve more than one million users. Interestingly, the proposed techniques can be implemented using the existing network monitoring infrastructure, specially for large networks, at a negligible additional investment.","Title: Assembly admission control based on random packet selection at border nodes in Optical Burst-Switched networks\nYear: 2009\n\nAbstract: In Optical Burst-Switched (OBS) networks employing Just Enough Time (JET) signalling, Burst-Control Packets request resources\n at intermediate nodes following a one-way reservation protocol, that is, requested resources are not confirmed back to the\n source. Hence, data bursts are transmitted without any guarantees, and it sometimes occurs that these are dropped at a certain\n hop in the source–destination path, hence wasting resources at previous hops. This effect is specially harmful if some connections\n are abusing of the global shared resources, violating their respective Service Level Agreements, thus causing: (1) global\n performance degradation; and, (2) unfair service received by other connections. This article proposes “Random Packet Assembly\n Admission Control”, an admission control mechanism for OBS networks that moderates the two problems above. The mechanism monitors\n the network load status, detects which links are heavily loaded and decides which flows among the total traversing them require\n throughput decrease, on attempts to alleviate congestion and benefit other flows which are not abusing from the network. Such\n throughput decrease consists of preventive packet dropping during the assembly process at the ingress nodes of the OBS network,\n thus making no use of the network core. The numerical results show a substantial increase in the throughput experienced by\n well-behaved flows, and fundamental fairness achievement in the use of optical resources.","Title: Analysis of average burst-assembly delay and applications in proportional service differentiation\nYear: 2007\n\nAbstract: In Optical Burst-Switched (OBS) networks, the limitation of optical buffering devices make it impractical to deploy conventional\n delay-based differentiation algorithms such as Active Queue Management, Weighted Fair Queuing, etc. Furthermore, only the\n delay that appears due to the burst-assembly process constitutes a variable quantity (all the other sources of delay are mostly\n fixed), it is then reasonable to make use of the burst-assembly algorithm to provide class-based delay differentiation. The\n aim of the following study is twofold: first it defines an average assembly delay metric, which represents the assembly delay\n experienced by a random arrival at the burst assembler of an edge OBS node; and second, this metric is used to define and\n configure a two-class burst-assembly policy, which gives preference to high-priority traffic over low-priority packet arrivals.\n The results show that, (1) tuning the parameters of the two-class assembly algorithm, the two classes of traffic exhibit different\n burst-assembly delay; and, (2) such parameters can be adjusted to provide a given differentiation ratio in the light of the\n proportional QoS differentiation approach proposed in the literature. A detailed analysis of the two-class assembly algorithm\n is given, along with an exhaustive set of experiments and numerical examples that validate the equations derived.","Title: Bridging the gap between hardware and software open source network developments\nYear: 2014\n\nAbstract: The rise of network speeds to tens of gigabits per second poses a challenge to develop packet processing applications that can cope with such bit rates. Therefore, the need for a suitable open source system that can be used as a prototype platform to test new network functionality while ensuring line-rate processing, accurate timestamping, and reduced power consumption has become evident. All these requirements cannot be achieved by using software-only solutions, but rather with hardware-based platforms such as NetFPGA. The main obstacle when using this type of open source FPGA-based solution is the cost of development, in both time and hardware development skills required. The spread of new circuit synthesis tools using high-level languages opens the door for the development of hardware-based networking applications with reasonable development effort, compared to the use of traditional hardware description languages. In this article, we describe how existing open source hardware-based platforms for networking applications will be fueled by the change in the programming model of FPGAs provided by modern high-level synthesis tools. For this, we implemented a network flow monitor using high-level languages and compared the effort spent with respect to a traditional hardware development cycle. Preliminary results are very promising, given that development time is reduced from months to weeks.","Title: Multi-Granular, Multi-Purpose And Multi-Gb/S Monitoring On Off-The-Shelf Systems\nYear: 2014\n\nAbstract: As an attempt to make network managers' life easier, we present M(3)Omon, a system architecture that helps to develop monitoring applications and perform network diagnosis. M(3)Omon behaves as an intermediate layer between the traffic and monitoring applications that provides advanced features, high performance and low cost. Such advanced features leverage a multi-granular and multi-purpose approach to the monitoring problem. Multi-granular monitoring provides answers to tasks that use traffic aggregates to identify an event, and requires either flow records or packet data or even both to understand it and, eventually, take convenient countermeasures. M(3)Omon provides a simple API to access traffic simultaneously at several different granularities, i.e. packet-level, flow-level and aggregate statistics. The multi-purposed design of M(3)Omon allows not only performing tasks in parallel that are specifically targeted to different traffic-related purposes (e.g. traffic classification and intrusion detection) but also sharing granularities between applications, e.g. several concurrent applications fed from flow records that are provided by M(3)Omon. Finally, the low-cost characteristic is brought by off-the-shelf systems (the combination of open-source software and commodity hardware) and the high performance is achieved thanks to modifications in the standard NIC driver, low-level hardware interaction, efficient memory management and programming optimization. Copyright (C) 2014 John Wiley & Sons, Ltd","Title: EFMP - a new congestion control mechanism for flow-aware networks\nYear: 2014\n\nAbstract: AbstractIn this paper, a new congestion control mechanism for flow-aware networks, that is, enhanced flushing mechanism with priority EFMP is introduced. Proposed by J. Roberts and S. Oueslati in 2004, flow-aware networking is a concept that ensures quality of service in networks based on flows. EFMP improves the efficiency of transmission in FAN by introducing new policies in the admission control block of a cross-protect router. The mechanism is thoroughly described, analysed, and validated through simulations. The proposed mechanism inherits the advantages of previously known admission control schemes while ensuring fast acceptance times of new streaming flows and proper transmission of the remaining traffic. Moreover, the comparison with the multilayer flow-aware networks architecture shows that EFMP ensures better performance and lower cost of transmission in a network with limited resources. Copyright © 2013 John Wiley & Sons, Ltd.","Title: Packet Storage at Multi-gigabit Rates Using Off-the-Shelf Systems\nYear: 2014\n\nAbstract: The use of closed solutions from most known vendors to carry out network-monitoring tasks has turned out to be a questionable option given their lack of flexibility and extensibility, which has typically been translated into higher costs. Consequently, we study whether high-performance monitoring tasks can be carried out using off-the-shelf systems, the alternative to these pitfalls from the research community, consisting in the combination of open-source software and commodity hardware. We focus on sniffing and storing network traffic as one of the major tasks in any monitoring architecture. Specifically, we first review the keys to sniff traffic at multi-gigabit rates, and then present an experimental evaluation of commodity hard drives. Finally, the lessons learned from such studies and the performed experiments have conducted us to the development of an open solution, namely text[HPCAP], which sniffs and stores multi-gigabit traffic using commodity hardware without packet losses in very demanding scenarios.","Title: TNT10G: A high-accuracy 10 GbE traffic player and recorder for multi-Terabyte traces\nYear: 2014\n\nAbstract: In this paper we present TNT10G (multi-Terabyte trace Network Tester), an FPGA-based tool for replaying and capturing massive Ethernet traces at 10 Gb/s. The tool is capable of reproducing and storing terabytes of network traffic at line rate, even if small packets are being used. Moreover, since the design works at low level (XGMII), accuracy is better than 10 ns, and it is also possible to observe and generate anomalous conditions, such as malformed frames, FCS errors, or illegal inter-frame gaps. All such features make TNT10G a truly useful tool for network testing and monitoring at 10 Gb/s. The design uses the NetFPGA-10G platform, although it could be easily ported to other boards since it uses standard AXI buses. The key element to achieve line-rate operation is a custom-developed Linux driver, which works in conjunction with a high-speed DMA backend core from Northwest Logic. Such blocks, together with a RAID0 array of commodity SSD disks, enable operation at 10 Gb/s. Finally, the use of a low-cost academic board together with off-the-shelf components allows for an open, extensible and cost-effective solution, a unique combination not found in commercial products.","Title: Selective Capping of Packet Payloads for Network Analysis and Management.\nYear: 2015\n\nAbstract: Both network managers and analysts appreciate the importance of network traces as a mechanism to understand traffic behavior, detect anomalies and evaluate performance in a forensic manner, among other applications. Unfortunately, the process of network capture and storage has become a challenge given the ever-increasing network speeds. In this scenario, we intend to make packets thinner to reduce both write speed and storage requirements on hard-drives and further reduce computational burden of packet analysis. To this end, we propose to remove the payload on those packets that hardly could be interpreted afterwards. Essentially, binary packets from unknown protocols fall into this category. On the other hand, binary packets from well-known protocols and protocols with some ASCII data are fully captured as potentially a network analyst may desire to inspect them. We have named this approach as selective capping, which has been implemented and integrated in a high-speed network driver as an attempt to make its operation faster and more transparent to upper layers. Its results are promising as it achieves multi-Gb/s rates in different scenarios, which could be further improved exploiting novel low-level hardware-software tunings to meet the fastest networks' rates.","Title: Jitter-based analysis and discussion of burst assembly algorithms\nYear: 2006\n\nAbstract: This work provides a jitter analysis of size-based burst assembly algorithms and also discusses other burst assem- bly algorithms that use the packet delay as the assembly threshold to provide a bound on jitter.","Title: Quality of Service analysis of Internet links with minimal information\nYear: 2013\n\nAbstract: Monitoring the Quality of Service (QoS) of Internet links is of paramount importance for network managers, and consequently has received great attention from the research community. To monitor QoS, practitioners leverage on network traffic measurements and, by means of practical models and statistical techniques, make predictions and detect outliers that allow the planning of telecommunication networks and detection of abnormal behavior, respectively. However, obtaining detailed measurements from Internet links at current network speeds is very challenging. Moreover, the amount of resources required to properly storage detailed network measurements make unfeasible to perform long measurement campaigns. These facts have motivated the application of techniques to reduce the information gathered from the network, such as sampling or the use of summarized statistics, making network traffic monitoring less demanding and allowing longer measurement campaigns. Accordingly, this thesis proposes two novel methodologies to perform QoS analysis of Internet links leveraging on summarized statistics of network traffic. Each methodology relies on a network traffic model, on which sound statistical methodologies are used on attempts of detecting relevant events that either require action from the network managers or are related with degradations of the provided QoS.","Title: Accurate and flexible flow-based monitoring for high-speed networks\nYear: 2013\n\nAbstract: In this paper we present an FPGA-based architecture to export flows in 10 Gbps networks, implemented on the NetFPGA-10G platform. Flow-based monitoring is a powerful methodology to analyze and detect network issues, such as congested links or DDoS attacks. Our design provides the following advantages: (i) The architecture allows processing 10 Gbps links without sampling, even for the highest packet rate of 14.88 Mpps (Million packets per second) that corresponds to the shortest (64-byte) Ethernet frames; (ii) It is possible to manage up to 786,432 concurrent flows; (iii) The project is developed in an open-source hardware platform and the HDL code is open to the community; (iv) The proposed approach frees network routers from the burden of exporting flows.","Title: Testing the capacity of off-the-shelf systems to store 10GbE traffic.\nYear: 2015\n\nAbstract: The maturity of the telecommunications market and the fact that user demands increase every day leaves network operators no option but to deploy high-speed infrastructures and test them in an efficient and economical manner. A common approach to this problem has been the storage of network traffic samples for analysis and replay using different versions of what we have named NTSS. This type of tas...","Title: Accurate and affordable packet-train testing systems for multi-gigabit-per-second networks\nYear: 2016\n\nAbstract: Communication networks these days face a relentless increase in traffic load. Multi-gigabitper- second links are becoming widespread, and network devices are under continuous stress, so testing whether they guarantee the specified throughput or delay is a must. Software-based solutions, such as packet-train traffic injection, were adequate for lower speeds, but they have become inaccurate in the current scenario. Hardware-based solutions have proved to be very accurate, but usually at the expense of much higher development and acquisition costs. Fortunately, new affordable FPGA SoC devices, as well as high-level synthesis tools, can very efficiently reduce these costs. In this article we show the advantages of hardware-based solutions in terms of accuracy, comparing the results obtained in an FPGA SoC development platform and in NetFPGA-10G to those of software. Results show that a hardware-based solution is significantly better, especially at 10 Gb/s. By leveraging high-level synthesis and open source platforms, prototypes were quickly developed. Noticeable advantages of our proposal are high accuracy, competitive cost with respect to the software counterpart, which runs in high-end off-the-shelf workstations, and the capability to easily evolve to upcoming 40 Gb/s and 100 Gb/s networks.","Title: Local Bifurcation Analysis In The Furuta Pendulum Via Normal Forms\nYear: 2000\n\nAbstract: Inverted pendulums are very suitable to illustrate many ideas in automatic control of nonlinear systems. The rotational inverted pendulum is a novel design that has some interesting dynamics features that are not present in inverted pendulums with linear motion of the pivot. In this paper the dynamics of a rotational inverted pendulum has been studied applying well-known results of bifurcation theory. Two classes of local bifurcations are analyzed by means of the center manifold theorem and the normal form theory - first, a pitchfork bifurcation that appears for the open-loop controlled system; second, a Hopf bifurcation, and its possible degeneracies, of the equilibrium point at the upright pendulum position, that is present for the controlled closed-loop system. Some numerical results are also presented in order to verify the validity of our analysis.","Title: Modification Via Averaging Of Partial-Energy-Shaping Control For Creating Oscillations: Cart-Pendulum Example\nYear: 2009\n\nAbstract: We consider the challenging problem of creating oscillations in underactuated mechanical systems. Target oscillatory motions of the indirectly actuated degree of freedom of a mechanical system can often be achieved via a straightforward to design feedback transformation. Moreover, the corresponding part of the dynamics can be forced to match a desired second-order system possessing the target periodic solution (Aracil, J., Gordillo, F., and Acosta, J.A. (2002), 'Stabilization of Oscillations in the Inverted Pendulum', in Proceedings of the 15th IFAC World Congress, Barcelona, Spain; Canudas-de-Wit, C., Espiau, B., and Urrea, C. (2002), 'Orbital Stabilisation of Underactuated Mechanical Systems', in Proceedings of the 15th IFAC World Congress, Barcelona, Spain). Sometimes, it is possible to establish the presence of periodic or bounded motions for the remaining degrees of freedom in the transformed system. However, typically this motion planning procedure leads to an open-loop unstable orbit and by necessity should be followed by a feedback control design. We propose a new approach for synthesis of a (practically) stabilising feedback controller, which ensures convergence of the solutions of the closed-loop system into a narrow tube around the preplanned orbit. The method is illustrated in detail by shaping oscillations in the inverted pendulum on a cart around its upright equilibrium. The complete analysis is based on application of a non-standard higher-order averaging technique assuming sufficiently high frequency of oscillations and is presented for this particular example.","Title: Proposal of a new information theory-based technique based on traffic anomaly detection analysis\nYear: 2015\n\nAbstract: The change-point detection theory is used to identify abrupt changes in the network traffic. The literature has focused on longitudinal traffic analysis, namely, detecting sudden peak changes, rather than analysing the traffic pattern on a 24 h typical day. As traffic varies throughout the day, it is essential to consider the concrete traffic period in which the anomaly occurs, which is useful for checking interconnection agreements amongst operators, something not possible with traditional sudden peak changes techniques. The aim of this paper is to analyse how the different algorithms behave in detecting changing points inside a typical day profile. We conclude that a combination of the algorithms provides better results than the use of a single one: in low traffic periods the tests of goodness-of-fit best detect changing conditions, while in normal traffic periods daytime entropy-based algorithms best detect traffic increases; besides, the statistical control charts complements both of them when detecting very abrupt changes regardless of the traffic load.","Title: Commodity Packet Capture Engines: tutorial, cookbook and applicability\nYear: 2015\n\nAbstract: Users’ demands have dramatically increased due to widespread availability of broadband access and new Internet avenues for accessing, sharing and working with information. In response, operators have upgraded their infrastructures to survive in a market as mature as the current Internet. This has meant that most network processing tasks (e.g., routing, anomaly detection, monitoring) must deal with challenging rates, challenges traditionally accomplished by specialized hardware — e.g., FPGA. However, such approaches lack either flexibility or extensibility —or both. As an alternative, the research community has proposed the utilization of commodity hardware providing flexible and extensible cost-aware solutions, thus entailing lower operational and capital expenditure investments. In this scenario, we explain how the arrival of commodity packet engines has revolutionized the development of traffic processing tasks. Thanks to the optimization of both NIC drivers and standard network stacks and by exploiting concepts such as parallelism and memory affinity, impressive packet capture rates can be achieved in hardware valued at a few thousand dollars. This tutorial explains the foundation of this new paradigm, i.e., the knowledge required to capture packets at multi-Gb/s rates on commodity hardware. Furthermore, we thoroughly explain and empirically compare current proposals, and importantly explain how apply such proposals with a number of code examples. Finally, we review successful use cases of applications developed over these novel engines.","Title: p‐Cycle configuration possibilities over DRDA networks\nYear: 2015\n\nAbstract: A resilience analysis of protection cycles (p-cycle) configurations for Double Rings with Dual Attachment (DRDAs) architectures is presented in this work. DRDAs are composed of two rings with corresponding nodes connected by two separated links. There are several possible configurations of p-cycles, which may be used in DRDAs for improving link or node protection upon link failure. The values of the parameters Mean Time To Failure and Mean Time To Disconnection are analysed in the paper to show the best choice of p-cycles in DRDAs architectures. Copyright (c) 2014 John Wiley & Sons, Ltd.","Title: Leveraging open source platforms and high-level synthesis for the design of FPGA-based 10 GbE active network probes\nYear: 2015\n\nAbstract: Nowadays, 10 Gb/s networks are becoming more and more widespread. Consequently, there is an increasing need for testing equipment for those networks, to measure parameters such as throughput, delay, jitter, packet loss rate, etc. Network testing equipment can be either active or passive, depending on whether it injects traffic or simply monitors packets in network links. In this paper we focus on active network probes, particularly those which are based on injection of packet trains. This type of probes have the advantage of causing little interference with existing network traffic, even though they are quite effective to measure several network parameters such as throughput or delay. Here, we take advantage of the open source NetFPGA project to implement a 10 GbE active monitoring probe based on the packet-train technique. In order to reduce development time, we used NetFPGA's OSNT (Open Source Network Tester) monitor project as a starting point, and we also used high-level synthesis tools (namely, Vivado-HLS) to implement the IP core in charge of computing network parameters. Such two design strategies turned out to be very effective both in terms of coding productivity and accuracy of measurements. Actually, the quality of measurements was found to be much better than that obtained with software solutions running on commodity servers, though the development effort was not significantly higher, thanks to the use of open source platforms and high-level synthesis techniques.","Title: Selective Capping of Packet Payloads at Multi-Gb/s Rates.\nYear: 2016\n\nAbstract: Network managers and analysts are well aware of the importance of network traces to understand traffic behavior, detect anomalies, and evaluate performance forensically, among others. However, the storage required for traffic traces has greatly expanded due to increasing network speeds. In this paper, we selectively cap the packet payload to reduce write speed and storage requirements on hard drives and further reduce the computational burden of packet analysis. The proposed techniques take advantage of most packet payloads being useless for analysis purposes, because they are either encrypted or in a proprietary application non-readable format. Conversely, non-ASCII packets from well-known protocols and protocols with some ASCII data are fully captured as they may be potentially useful for network analysis. We have named this approach as selective capping, and we have implemented and integrated it into a high-speed network driver and a software module at user level, to make its operation more transparent and faster to upper layer applications. The results are promising, and selective capping achieves multi-Gb/s rates by exploiting low-level hardware and software techniques to meet the fastest network rates.","Title: Multi-Gbps HTTP traffic analysis in commodity hardware based on local knowledge of TCP streams.\nYear: 2017\n\nAbstract: In this paper we propose and implement novel techniques for performance evaluation of web traffic (response time, response code, etc.), with no reassembly of the underlying TCP connection, which severely restricts the traffic analysis throughput. Furthermore, our proposed software for HTTP traffic analysis runs in standard hardware, which is very cost-effective. Besides, we present sub-TCP connection load balancing techniques that significantly increase throughput at the expense of losing very few HTTP transactions. Such techniques provide performance evaluation statistics which are indistinguishable from the single-threaded alternative with full TCP connection reassembly.","Title: Context-aware security framework based on Traffic Anomaly Detection Indicator.\nYear: 2017\n\nAbstract: Context-aware security utilizes external data, such as time of the day or user information, to improve its capability of detecting a security breach. In this paper we present a Context-aware security framework based on a Traffic Anomaly Detection Indicator (TADI) which indicates when a threat can occur. The main novelty of our approach is that we use as a context the time-based information derived from profile analysis of a typical day to determine more accurately the presence of an anomaly based on the time of day it occurs. This 24-h typical daily analysis helps us to consider the time interval (night-time, working hours, etc.) in which a potential threat occurs, in contrast to traditional sudden peak changes. First, a preliminary analysis based on historical data shows how traffic typically behaves at each particular period of the day. We subsequently calibrate our procedure by checking the effectiveness of different algorithms so that we are aware of which ones gets better performance in each period of the day. Finally the TADI is calculated from the time-based contextual information. We also present the results based on actual traffic traces collected from a campus university that show the effectiveness of the proposed method.","Title: Loginson: a transform and load system for very large-scale log analysis in large IT infrastructures\nYear: 2017\n\nAbstract: AbstractNowadays, most systems and applications produce log records that are useful for security and monitoring purposes such as debugging programming errors, checking system status, and detecting configuration problems or even attacks. To this end, a log repository becomes necessary whereby logs can be accessed and visualized in a timely manner. This paper presents Loginson, a high-performance log centralization system for large-scale log collection and processing in large IT infrastructures. Besides log collection, Loginson provides high-level analytics through a visual interface for the purpose of troubleshooting critical incidents. We note that Loginson outperforms all of the other log centralization solutions by taking full advantage of the vertical scalability, and therefore decreasing Capital Expenditure (CAPEX) and Operating Expense (OPEX) costs for deployment scenarios with a huge volume of log data.","Title: A Novel Blind Traffic Analysis Technique For Detection Of Whatsapp Voip Calls\nYear: 2017\n\nAbstract: Nowadays social media plays a key role in interpersonal communication. Instant messaging applications, such as WhatsApp, are used by billions of users every day. Such application has recently been upgraded to support voice calls, whose traffic is transported over the top of network operators, as many other Voice over Internet Protocol (VoIP) services. In this work, we have characterized WhatsApp voice calls through blind traffic detection, which allows to differentiate WhatsApp calls from other applications, such as sharing video, photo, or messaging. Traditional techniques for detection of VoIP calls cannot be applied to the WhatsApp case because the traffic is obfuscated. Actually, our proposal only takes into account the WhatsApp traffic stream statistical features, and not the packet content. From the operators' point of view, the benefits of such a tool are manifold: from traffic prioritization to bespoke marketing campaigns to users that heavily produce WhatsApp voice calls.","Title: Application of functional feature extraction to the compression of network time series\nYear: 2017\n\nAbstract: Network management actions require the retention of data representing the temporal evolution of network state, mainly in the form of time series. Nonetheless, storing and exploiting those measurements is becoming a challenge as the production rate of such data is continuously increasing and data lasting for long time periods are used. To scale up the storage and improve both the analysis and visualization of network measurements, we apply Functional Principal Components Analysis (FPCA) to extract the most meaningful functional features for network time series, pruning those with low informational importance. We compare such algorithm with other state-of-the-art proposals, and show that it achieves lower error for the representation of atypical observations even with higher compression ratios.","Title: On the impact of TCP segmentation: Experience in VoIP monitoring.\nYear: 2017\n\nAbstract: Quality of Service (QoS) and Experience (QoE) monitoring is a must during the management of services deployed over the Internet. This is particularly critical for Voice over IP (VoIP), as its degradation is immediately perceived by end users. From our experience, we highlight the impact that TCP segmentation exerts on online VoIP monitoring systems. On the one hand, it makes difficult to interpret the segmented signaling messages for application monitoring. On the other hand, complete messages do not provide information about packet level behavior, which is necessary for internetworking layer monitoring. Paradoxically, the Network Management community has not paid much attention to this fact, although it compromises several VoIP management tasks. To fill in this gap, we provide an empirical evaluation of its impact for the most popular VoIP signaling protocols using traces from enterprise networks, and present the architecture and heuristic that we are currently developing to partially solve the effect of the segmentation. Our proposal avoids the overhead of reconstructing the entire data stream and, at the same time, it enables the analysis of the packets that are actually sent. To do so, it maps TCP flags with segmented application messages, and exploits data structures that reduce latency. In this way, our solution paves the way for online monitoring tools that take into account both internetworking and application layers performance.","Title: Valley times in the Spanish academic network\nYear: 2017\n\nAbstract: The scheduling of bulk transfers such as database distribution, resources replication and security backups, and other non-time-critical tasks has a direct effect on both the performance and cost of a network. We propose to face this problem by studying the valley times - i.e., the minimum use during off-peak periods of a network - as suitable moments to carry out such tasks. To do so, we characterize them considering the valley-hour, which we define as the opposite to the well-known variable busy-hour. Our analysis, based on 6-year-long measurements from 12 points of presence in the Spanish Research and Education Network (RedIRIS), has guided us to model the valley-hour as a Gaussian process. After that, we compare its behavior in different points and detect the main factors that explain its variance, finding significant heterogeneity. With the resulting conclusions, we have proposed a system to predict valley-hours in RedIRIS with errors below an hour for most of the cases.","Title: Partial-Energy-Shaping Control For Orbital Stabilization Of High Frequency Oscillations Of The Furuta Pendulum\nYear: 2007\n\nAbstract: We consider the problem of creating oscillations of the Furuta pendulum around the open-loop unstable equilibrium. Following a recently proposed technique, we start with shaping the energy of the unactuated link. An dissipativity-based controller is designed to create oscillations, neglecting possibility of unbounded motion of the directly actuated link. After that, an auxiliary linear feedback action is added to the control law, stabilizing a desired level of the reshaped energy. Parameters of the controller are tuned to approximately keep the originally created oscillations but ensuring bounded motion of both links. The analysis is valid only for oscillations of sufficiently high frequency and is based on higher order averaging technique. Performance of the designed controller is verified using numerical simulations and experiments.","Title: Loginson: a transform and load system for very large-scale log analysis in large IT infrastructures.\nYear: 2017\n\nAbstract: Nowadays, most systems and applications produce log records that are useful for security and monitoring purposes such as debugging programming errors, checking system status, and detecting configuration problems or even attacks. To this end, a log repository becomes necessary whereby logs can be accessed and visualized in a timely manner. This paper presents , a high-performance log centralization system for large-scale log collection and processing in large IT infrastructures. Besides log collection, provides high-level analytics through a visual interface for the purpose of troubleshooting critical incidents. We note that outperforms all of the other log centralization solutions by taking full advantage of the vertical scalability, and therefore decreasing Capital Expenditure (CAPEX) and Operating Expense (OPEX) costs for deployment scenarios with a huge volume of log data.","Title: Diluting the Scalability Boundaries: Exploring the Use of Disaggregated Architectures for High-Level Network Data Analysis\nYear: 2017\n\nAbstract: Traditional data centers are designed with a rigid architecture of fit-for-purpose servers that provision resources beyond the average workload in order to deal with occasional peaks of data. Heterogeneous data centers are pushing towards more cost-efficient architectures with better resource provisioning. In this paper we study the feasibility of using disaggregated architectures for intensive data applications, in contrast to the monolithic approach of server-oriented architectures. Particularly, we have tested a proactive network analysis system in which the workload demands are highly variable. In the context of the dReDBox disaggregated architecture, the results show that the overhead caused by using remote memory resources is significant, between 66% and 80%, but we have also observed that the memory usage is one order of magnitude higher for the stress case with respect to average workloads. Therefore, dimensioning memory for the worst case in conventional systems will result in a notable waste of resources. Finally, we found that, for the selected use case, parallelism is limited by memory. Therefore, using a disaggregated architecture will allow for increased parallelism, which, at the same time, will mitigate the overhead caused by remote memory.","Title: Facing Network Management Challenges with Functional Data Analysis: Techniques & Opportunities.\nYear: 2017\n\nAbstract: Current fixed and mobile networks’ behavior is rapidly changing, which calls for flexible monitoring approaches to avoid loosing track with such a fast evolutionary pace. Due to the many challenges that this scenario is posing to network managers, we propose the exploration of Functional Data Analysis (FDA) techniques as a mean to easily deal with network management and analysis issues. Specifically, we describe and evaluate several FDA methods with applications to network measurement preprocessing and clustering, bandwidth allocation, and anomaly and outlier detection. Our work focuses on how these FDA-based tools serve to improve the outcomes of traffic data mining and analysis, providing easy-to-understand and comprehensive outputs for network managers. We present the results that we have obtained from real case studies in the Spanish Academic network using throughput time series, comparing them with other alternatives of the state of the art. With this com- parative, we have qualitatively and quantitatively evaluated the advantages of FDA-methods in the networking area.","Title: FlexiTop: a flexible and scalable network monitoring system for Over-The-Top services.\nYear: 2017\n\nAbstract: Nowadays, the demand of Over-The-Top (OTT) services such as multimedia streaming, web services or social networking is rapidly increasing. Consequently, there is a wide interest in studying the quality of these services so that Internet Service Providers (ISP) can deliver the best experience to their clients. For this purpose, we present FlexiTop, a flexible and scalable system to actively monitor these OTT services, which allows an operator to obtain metrics with a limited resource usage. Due to the continuous evolution of OTT services, this system was designed with different approaches that can be extrapolated to future situations. By looking at the results, the proposal meets all the expectations and requirements and therefore it proves its success. The proposed design was implemented and validated with different alternatives whenever it was possible, both in wired and wireless networks. Moreover, long-time testing was performed to both ensure its stability and analyze the obtained data.","Title: On The Use Of Affordable Cots Hardware For Network Measurements: Limits And Good Practices\nYear: 2018\n\nAbstract: Wireless access technologies are widespread in domestic scenarios, and end users extensively use mobile phones or tablets to browse the Web. Therefore, methods and platforms for the measurement of network key performance indicators must be adapted to the peculiarities of this environment. In this light, the experiments should capture the true conditions of such connections, particularly in terms of the hardware and multi-device interactions that are present in real networks. On the basis of this, this paper presents an evaluation of the capabilities of several affordable commercial off-the-shelf (COTS) devices as network measuring probes, for example, computers-on-module or domestic routers with software measurement tools. Our main goal is to detect the limits of such devices and define a guide of good practices to optimize them. Hence, our work paves the way for the development of fair measurement systems in domestic networks with low expenditures. The obtained experimental results show that these types of devices are suitable as network measuring probes, if they are adequately configured and minimal accuracy losses are assumable.","Title: Estimation of the parameters of token-buckets in multi-hop environments.\nYear: 2018\n\nAbstract: Bandwidth verification in shaping scenarios receives much attention of both operators and clients because of its impact on Quality of Service (QoS). As a result, measuring shapers’ parameters, namely the Committed Information Rate (CIR), Peak Information Rate (PIR) and Maximum Burst Size (MBS), is a relevant issue when it comes to assess QoS. In this paper, we present a novel algorithm, TBCheck, which serves to accurately measure such parameters with minimal intrusiveness. These measurements are the cornerstone for the validation of Service Level Agreements (SLA) with multiple shaping elements along an end-to-end path. As a further outcome of this measurement method, we define a formal taxonomy of multi-hop shaping scenarios. A thorough performance evaluation covering the latter taxonomy shows the advantages of TBCheck compared to other tools in the state of the art, yielding more accurate results even in the presence of cross-traffic. Additionally, our findings show that MBS estimation is unfeasible when the link load is high, regardless the measurement technique, because the token-bucket will always be empty. Consequently, we propose an estimation policy which maximizes the accuracy by measuring CIR during busy hours and PIR and MBS during off-peak hours.","Title: DNS weighted footprints for web browsing analytics.\nYear: 2018\n\nAbstract: The monetization of the large amount of data that ISPs have of their users is still in early stages. Specifically, the knowledge of the websites that specific users or aggregates of users visit opens new opportunities of business, after the convenient sanitization. However, the construction of accurate DNS-based web-user profiles on large networks is a challenge not only because the requirements that capturing traffic entails, but also given the use of DNS caches, the proliferation of botnets and the complexity of current websites (i.e., when a user visit a website a set of self-triggered DNS queries for banners, from both same company and third parties services, as well for some preloaded and prefetching contents are in place). In this way, we propose to count the intentional visits users make to websites by means of DNS weighted footprints. Such novel approach consists of considering that a website was actively visited if an empirical-estimated fraction of the DNS queries of both the own website and the set of self-triggered websites are found. This approach has been coded in a final system named DNSprints. After its parameterization (i.e., balancing the importance of a website in a footprint with respect to the total set of footprints), we have measured that our proposal is able to identify visits and their durations with false and true positives rates between 2 and 9% and over 90%, respectively, at throughputs between 800,000 and 1.4 million DNS packets per second in diverse scenarios, thus proving both its refinement and applicability.","Title: High-speed optical networks latency measurements in the microsecond timescale with software-based traffic injection.\nYear: 2018\n\nAbstract: In many optical network scenarios, such as Storage Array Network (SAN) replication, keeping latency under control is cornerstone to provide a proper Quality of Service (QoS). Hence, measuring latencies in such optical networks becomes fundamental. However, for low distances, microseconds resolution is required, which, in turn, demands ad-hoc hardware implementation for the measurement device. Alternatively, a more cost-effective solution is that of software-based methods, but up to date they were not precise enough at 10 Gbit/s or above. In this paper, we analyze current high-performance packet engines, such as DPDK, and pinpoint the issues involved when it comes to measure latencies in high-speed optical networks. Based on these findings, we propose the use of a software-based solution to measure latency. Furthermore, we also propose an extension that serves to measure bandwidth as well, with the novel concept of convoy of packet trains.","Title: On the analysis of burst-assembly delay in OBS networks and applications in delay-based service differentiation\nYear: 2007\n\nAbstract: Optical Burst Switching (OBS), packets travel through the network core as part of longer-size optical bursts, which do not suffer electronic conversion until they reach an eggress point. Typically, such optical bursts comprise tens or hundreds of packets, which are assembled/deassembled at border nodes. During the burst-formation process, each arriving packet must wait until the final burst is complete, which clearly adds an extra delay on each packet in the burst, especially on those arriving earlier. However, such burst-assembly delay may be excessive for the appropriate performance of certain applications, mainly real-time interactive ones. This work's findings are twofold: first, it characterises the burst-assembly delay distribution of each packet in a burst arisen by the main assembly algorithms found in the literature; and, second, it introduces a new burst-assembly strategy that takes into account the particular delay constrains of packets in the formation of optical bursts, along with a detailed study of its properties.","Title: On Burst Length Distribution and Preemption Probabilities in OBS Networks with Burst Segmentation\nYear: 2006\n\nAbstract: Recently, preemption techniques have attracted considerable attention as a means to provide differentiated quality of service in optical burst switching (OBS) networks. This paper is focused on the analysis of preemption probabilities for bursts within the same priority class. As proposed by Vokkarane and Jue ((2003)* IEEE J Select Areas Commun 21(7): 1198-1209) an incoming burst will preempt the burst in service, within the same priority class, if the residual length of the burst in service is smaller than the incoming burst length. For a general case with wavelength conversion, the preemption probability of contending bursts with a generic service distribution, not necessarily exponential, is analyzed. First, we show that the size distribution for the preempting bursts is shifted to larger values, in comparison to the original burst size distribution. Second, we obtain an upper and lower bound for the preemption probability. Finally, the asymptotic behavior of the OBS switch is analyzed showing that preemption will always occur for a very large number of wavelengths.","Title: Online detection of pathological TCP flows with retransmissions in high-speed networks.\nYear: 2018\n\nAbstract: Online Quality of Service (QoS) assessment in high speed networks is one of the key concerns for service providers, namely to detect QoS degradation on-the-fly as soon as possible and avoid customers’ complaints. In this regard, a Key Performance Indicator (KPI) is the number of TCP retransmissions per flow, which is related to packet losses or increased network and/or client/server latency. However, to accurately detect TCP retransmissions the whole sequence number list should be tracked which is a challenging task in multi-Gb/s networks.","Title: Making It Useful Even When It Seems to Be Useless [Opinion].\nYear: 2018\n\nAbstract: Discusses how technology has played an essential role in the process of hominization. For humans, using technology to create an artificial world is as natural as it is for predators to hunt and kill their prey. In this respect, technology is inherent to human beings: there would be no humankind without technology, nor would there be technology without sociability. This leads to the core of technol...","Title: On the design and performance evaluation of automatic traffic report generation systems with huge data volumes\nYear: 2018\n\nAbstract: AbstractSummaryIn this paper, we analyze the performance issues involved in the generation of automated traffic reports for large IT infrastructures. Such reports allow the IT manager to proactively detect possible abnormal situations and roll out the corresponding corrective actions. With the ever‐increasing bandwidth of current networks, the design of automated traffic report generation systems is very challenging. In a first step, the huge volumes of collected traffic are transformed into enriched flow records obtained from diverse collectors and dissectors. Then, such flow records, along with time series obtained from the raw traffic, are further processed to produce a usable report. As will be shown, the data volume in flow records turns out to be very large as well and requires careful selection of the key performance indicators (KPIs) to be included in the report. In this regard, we discuss the use of high‐level languages versus low‐level approaches, in terms of speed and versatility. Furthermore, our design approach is targeted for rapid development in commodity hardware, which is essential to cost‐effectively tackle demanding traffic analysis scenarios. Actually, the paper shows feasibility of delivering a large number of KPIs, as will be detailed later, for several TBytes of traffic per day using a commodity hardware architecture and high‐level languages.We analyze the performance issues involved in the generation of automated traffic reports for large IT infrastructures. Such reports allow the IT manager to proactively detect possible abnormal situations and roll out the corresponding corrective actions. With the ever‐increasing bandwidth of current networks, the design of automated traffic report generation systems is very challenging. Our approach is targeted for rapid development in commodity hardware, which is essential to cost‐effectively tackle demanding traffic analysis scenarios. View Figure","Title: KISS Methodologies for Network Management and Anomaly Detection\nYear: 2019\n\nAbstract: Current networks are increasingly growing in size, complexity and the amount of monitoring data that they produce, which requires complex data analysis pipelines to handle data collection, centralization and analysis tasks. Literature approaches, include the use of custom agents to harvest information and large data centralization systems based on clusters to achieve horizontal scalability, which are expensive and difficult to deploy in real scenarios. In this paper we propose and evaluate a series of methodologies, deployed in real industrial production environments, for network management, from the architecture design to the visualization system as well as for the anomaly detection methodologies, that intend to squeeze the vertical resources and overcome the difficulties of data collection and centralization.","Title: On the design and performance evaluation of automatic traffic report generation systems with huge data volumes.\nYear: 2018\n\nAbstract: In this paper we analyze the performance issues involved in the generation of auto- mated traffic reports for large IT infrastructures. Such reports allows the IT manager to proactively detect possible abnormal situations and roll out the corresponding cor- rective actions. With the ever-increasing bandwidth of current networks, the design of automated traffic report generation systems is very challenging. In a first step, the huge volumes of collected traffic are transformed into enriched flow records obtained from diverse collectors and dissectors. Then, such flow records, along with time series obtained from the raw traffic, are further processed to produce a usable report. As will be shown, the data volume in flow records is very large as well and requires careful selection of the Key Performance Indicators (KPIs) to be included in the report. In this regard, we discuss the use of high-level languages versus low- level approaches, in terms of speed and versatility. Furthermore, our design approach is targeted for rapid development in commodity hardware, which is essential to cost-effectively tackle demanding traffic analysis scenarios.","Title: Wormhole: a novel big data platform for 100 Gbit/s network monitoring and beyond\nYear: 2019\n\nAbstract: Internet measurement and analysis is increasingly challenging as the Internet evolves, primarily due to changing-trends, speed increments or new protocols and ciphers. As such, ad-hoc monitoring equipment comes in handy, albeit cost-effectiveness impedes deployment at a very large scale. As an alternative, big data-based distributed architectures are being proposed for network monitoring and analysis. However, in light of the high throughput currently offered by 100 Gbit/s links, it turns out that state-of-the-art big data solutions fall short of capacity, unless a huge amount of computers are used. In order to effectively tackle that issue, we have created Wormhole: a streaming engine that circumvents existing limitations by distributing the input messages/packets coherently among different off-the-shelf analysis equipment, thus reducing costs and equipment. Should the incoming data rate be larger than the system throughput, a distributed file system can be used for temporary data storage, for subsequent filtering and in-depth analysis. The proposed solution provides on-line real-time monitoring metrics with the ability to gain further insights when required. The prototyped architecture is able to deal with 100 Gbit/s networks and can be easily scaled up to higher rates by just adding more computing nodes and/or by trimming encrypted packet payloads.","Title: Flow-concurrence and bandwidth ratio on the Internet\nYear: 2019\n\nAbstract: The relevance of flow-based monitoring in tasks such as the detection of anomalies and denial of use attacks, traffic reporting, performance evaluation, software routing among others motivates the study of the Internet traffic in terms of flows. However, by the time a network manager or practitioner start any of these tasks, they face the challenge of planning probes’ capacities, which depends on the number of concurrent flows. Unfortunately, while the bandwidth of a network or link, both in operation and in future deployments, can be known, or at least estimated in advance, nothing is known about the load in terms of concurrent flows. We aimed at filling this gap by studying the concurrence of flows with respect to the bandwidth normalized by factors such as protocol shares, timeouts, applications, time and years among others. As a result, we provide the research community with several models, based on lognormal distributions, and parameter estimates in such a way that any player in the Internet arena can estimate the number of concurrent flows in their own infrastructure. Moreover, such results emerge from a diverse set of network traces so making the extrapolation of conclusions viable."],"string":"[\n \"Title: Brief Hopf bifurcation in indirect field-oriented control of induction motors\\nYear: 2002\\n\\nAbstract: The appearance of self-sustained oscillations in high performance AC drives, and in particular, in induction motors whose speed is regulated with the industry standard field-oriented control, is a well-documented but little understood phenomenon. It is well known that the oscillations may be quenched by returning the outer-loop PI speed control, but no precise rules to carry out this task, which may be time consuming, are known. In this paper, we show that these oscillations may arise due to the existence of Hopf bifurcations. Some simple rules for selecting the gains of the PI controller are obtained as a result of our analysis.\",\n \"Title: Performance analysis of asynchronous best-effort traffic coexisting with TDM reservations in polymorphous OBS networks\\nYear: 2009\\n\\nAbstract: The in-advance reservation of bandwidth capacity philosophy of Optical Burst Switching architectures via Burst-Control Packets\\n brings high flexibility in the separation of network resources for services with different quality-of-service requirements.\\n In this light, real-time applications can periodically be guaranteed a certain amount of bandwidth reservation for the transmission\\n of traffic with Constant Bit Rate requirements (for instance IP television, VoIP, etc), whilst the remaining capacity may\\n be used for transmission of best-effort traffic of the so-called elastic applications (e-mailing, web browsing, etc). The\\n Polymorphous, Agile and Transparent Optical Networks (PATON) architecture (Qiao et al. IEEE Commu Mag 44(12):104–114 2006)\\n proposes periodic reservation of time-slots over one or several wavelengths of an optical fibre, yet remaining gaps in between\\n them for transmission of best-effort traffic. This work presents a novel analysis of the performance perceived by best-effort\\n traffic which are given full access to optical switching only during a portion of the total time. The following analyses the\\n non-blocking probability among best-effort data bursts that share such available gaps in between the periods of CBR traffic.\\n An exact expression of the non-blocking probability is derived when a single wavelength is used for CBR traffic, along with\\n a lower bound for the case when CBR traffic is transmitted using multiple wavelengths. These results can be of further interest\\n in the optimal design of OBS architectures where the transmission of high-priority real-time traffic and best-effort data\\n coexist over the same wavelength.\",\n \"Title: Characterization of the busy-hour traffic of IP networks based on their intrinsic features\\nYear: 2011\\n\\nAbstract: Internet traffic measurements collected during the busy hour constitute a key tool to evaluate the operation of networks under the heaviest-load case scenarios, and further provide a means to network dimensioning and capacity planning. In this light, this study provides a throughout analysis of the busy-hour traffic measurements of an extensive set of universities, regional networks, and Internet exchange points collected from the Spanish Research and Education Network, RedIRIS. After showing that the traffic volumes observed in the busy hour over time can be modeled by a white Gaussian process, this work takes one step further and examines the influence of the networks' intrinsic features, mainly population size and access link capacity, on the busy-hour traffic. Well-known statistical methodologies, such as ANOVA and ANCOVA, show that the network size in terms of number of users justifies most of the busy-hour traffic information. We further provide a linear-regression model that adjusts the amount of traffic that each network user contributes to the busy-hour traffic mean values, with a direct application to the problem of link capacity planning of IP networks.\",\n \"Title: Is multilayer networking feasible?\\nYear: 2009\\n\\nAbstract: IP traffic has been growing every year, bringing the need for deploying an IP backbone interconnected by links provided by the transport network. Thus, network operators have had traditionally divided their core network in two, the IP network and the transport network. Network planning and engineering tasks have been performed independently in both domains. Traditionally, the transport network has been quite inflexible, and changes have often required a long time to occur. However, recent developments in the control plane allow flexibility in the transport network, making it possible to set up and tear down circuits on demand. In this light, multilayer traffic engineering has been proposed to jointly manage both IP and transport layers, with the aim of optimizing the use of resources. This paper aims to describe the rationale behind multilayer traffic engineering, demonstrate its feasibility and quantify its advantages in terms of cost effectiveness. Also, this work takes a look at the different choices in performing the multilayer operation, in terms of control plane implementation and equipment integration. Finally, the paper presents a report on multilayer traffic engineer experimentation which proves its feasibility and show a preliminary techno-economic case study of the multilayer operation.\",\n \"Title: On the Early Release of Burst-Control Packets in Optical Burst-Switched Networks\\nYear: 2007\\n\\nAbstract: In Optical Burst-Switched networks, the so-called Burst-Control Packet is sent a given offset-time ahead of the optical data burst to advertise the imminent burst arrival, and reserve a time-slot at each intermediate node to allocate it. This work proposes a methodology to estimate the number of packets to arrive in a given amount of time, in order to make it possible to send the BCP packet straightafter the first packet arrival and reduce the latency experienced during the burst-assembly process. The following studies the impact of a wrong guess in terms of over-reservation of resources and waiting-time at the assembler, providing a detailed characterisation of their probability density functions. Additionally, a case example in a scenario with non-homogeneous Poisson arrivals is analysed and it is shown how to choose the appropriate burst-assembly algorithm values to never exceed a given over-reservation amount.\",\n \"Title: A Bayesian decision theory approach for the techno-economic analysis of an all-optical router\\nYear: 2007\\n\\nAbstract: Typically, core networks are provided with both optical and electronic physical layers. However, the interaction between the two layers is at present limited, since most of the traditional transport functionalities, such as traffic engineering, switching and restoration, are carried in the IP/MPLS layer. In this light, the research community has paid little attention to the potential benefits of the interaction between layers, multilayer capabilities, on attempts to improve the Quality of Service control. This work shows when to move incoming Label Switched Paths (LSPs) between layers based on a multilayer mechanism that trades off a QoS metric, such as end-to-end delay, and techno-economic aspects. Such mechanism follows the Bayesian decision theory, and is tested with a set of representative case scenarios.\",\n \"Title: Detection of traffic changes in large-scale backbone networks: The case of the Spanish academic network\\nYear: 2012\\n\\nAbstract: Network management systems produce a huge amount of data in large-scale networks. For example, the Spanish academic network features hundreds of access and backbone links, each of which produces a link utilization time series. For the purpose of detecting relevant changes in traffic load a visual inspection of all such time series is required. As a result, the operational expenditure increases. In this paper, we present an on-line change detection algorithm to identify the relevant change points in link utilization, which are presented to the network manager through a graphical user interface. Consequently, the network manager only inspects those links that show a stationary and statistically significant change in the link load.\",\n \"Title: Admission control in Flow-Aware Networking (FAN) architectures under GridFTP traffic\\nYear: 2009\\n\\nAbstract: Computing and networking resources virtualization is the main objective of Grid services. Such a concept is already used in the context of Web-services on the Internet. In the next few years, a large number of applications belonging to various domains (biotechnology, banking, finance, car and aircraft manufacturing, nuclear energy etc.) will also benefit from Grid services. Admission control is a key functionality for Quality of Service (QoS) provision in IP networks, and more specifically for Grid services provision. Service differentiation (DS) is a widely deployed technique on the Internet. It operates at the packet level on a best-effort mode. Flow-Aware Networking (FAN) that operates at the scale of the IP flows relies on implicit flow differentiation through priority fair queuing (PFQ). It may be seen as an alternative to DS. A Grid session may be seen as a succession of parallel TCP/IP flows characterized by data transfers with much larger volume than usual TCP/IP flows. In this paper, we propose an extension of FAN for the Grid environment called Grid over FAN (GoFAN). We compare, by means of computer simulations, the efficiency of Grid over DS (GoDS) and GoFAN. Two variants of GoFAN architectures based on different fair queuing algorithms are considered. As a first step, we provide two short surveys on QoS for Grid environment and on QoS in IP networks respectively.\",\n \"Title: On the processing time for detection of Skype traffic.\\nYear: 2011\\n\\nAbstract: The last few years have witnessed VoIP applications gaining a tremendous popularity and Skype, in particular, is leading this continuous expansion. Unfortunately, Skype follows a closed source and proprietary design, and typically uses encryption mechanisms, making it very difficult to identify its presence from a traffic aggregate. Several algorithms and approaches have been proposed to perform such task with promising results in terms of accuracy. However, such approaches typically require significant computation resources and it is unlikely that they can be deployed in nowadays high-speed networks. In this light, this paper focuses on cutting the processing cost of algorithms to detect Skype traffic. We have conveniently tuned a previous well-validated algorithm and we have assessed its performance. To this end, we have used real traces from public repositories, from a Spanish 3G operator, and synthetic traces. Our results show that a single process can detect Skype traffic at 1 Gbps rates reading replayed real traces directly from a NIC. Even more, 3.7 Gbps are achieved reading from traces previously allocated in memory using a single process and 45 Gbps using 16 concurrent processes. This fact paves the way for 10 Gbps processing in commodity hardware.\",\n \"Title: FPGA acceleration using high-level languages of a Monte-Carlo method for pricing complex options\\nYear: 2013\\n\\nAbstract: In this paper we present an FPGA implementation of a Monte-Carlo method for pricing Asian options using Impulse C and floating-point arithmetic. In an Altera Stratix-V FPGA, a 149x speedup factor was obtained against an OpenMP-based solution in a 4-core Intel Core i7 processor. This speedup is comparable to that reported in the literature using a classic HDL-based methodology, but the development time is significantly reduced. Additionally, the use of a HLL-based methodology allowed us to implement a high-quality Gaussian random number generator, which produces more precise results than those obtained with the simple generators usually present in HDL-based designs.\",\n \"Title: Low-Cost And High-Performance: Voip Monitoring And Full-Data Retention At Multi-Gb/S Rates Using Commodity Hardware\\nYear: 2014\\n\\nAbstract: Voice over IP (VoIP) is increasingly replacing the old public switched telephone network (PSTN) technology. In this new scenario, there are several challenges for VoIP providers. First, VoIP requires a detailed monitoring of both users' quality of service (QoS) and experience (QoE) to a greater extent than in traditional PSTNs. Second, such a monitoring process must be able to track VoIP traffic in high-speed networks, nowadays typically of multi-Gb/s rates. Third, recent government directives require that providers retain information from their users' calls. Similarly, the convergence of data and voice services allows operators to provide new services such as full-data retention, in which users' calls can be recorded for either quality assessment (call centers, QoE) or security purposes (lawful interception). This implies a significant investment in infrastructure, especially in large-scale networks which require multiple points of measurement and redundancy. This paper proposes a novel methodology, architecture and system to fulfill such challenges, called VoIPCallMon, as well as the data structures and necessary hardware-tuning knowledge for its development. As distinguishing features, VoIPCallMon provides very high performance, being able to process VoIP traffic on-the-fly at high bitrates, novel services and significant cost reduction by using commodity hardware with minimal interference with operational VoIP networks. The performance evaluation shows that the system copes with the VoIP load of real-world operators. We further evaluated the system performance at a fully saturated 10 Gb/s link and no packet loss was reported, therefore demonstrating the potential of commodity hardware solutions. Copyright (c) 2014 John Wiley & Sons, Ltd.\",\n \"Title: Codimension-Two Bifurcations In Indirect Field Oriented Control Of Induction Motor Drives\\nYear: 2008\\n\\nAbstract: This paper provides further results on bifurcation analysis of indirect field oriented control of induction motors. Previous results presented on this subject [Bazanella & Reginatto, 2000, 2001; Gordillo et al., 2002] are summarized and extended by means of a codimension-two bifurcation analysis. It is shown that codimension-two bifurcation phenomena, such as a Bogdanov-Takens and zero-Hopf bifurcations, occur in IFOC as a result of parameter mismatch and certain setting of the proportional-integral speed controller. Conditions for the existence of such bifurcations are derived analytically, as long as possible, and bifurcation diagrams are presented with the help of simulation and numerical bifurcation analysis.\",\n \"Title: Blocking models of optical burst switches with shared wavelength converters: exact formulations and analytical approximations\\nYear: 2008\\n\\nAbstract: Loss modeling of asynchronous optical burst switches with shared wavelength converters is considered. An exact analysis based\\n on continuous time Markov chains is proposed and validated by comparison with simulation for balanced and unbalanced traffic.\\n A computationally efficient approximated analysis is also proposed and compared with the exact model to find applicability\\n conditions. Approximate loss performance evaluation is presented for ranges of values which are not tractable either by simulation\\n or exact analysis.\",\n \"Title: A queueing equivalent thresholding method for thinning traffic captures\\nYear: 2008\\n\\nAbstract: In the development of accurate capacity planning and network resource dimensioning models, network operators must handle representative information about the traffic volumes traversing its network. However, the amount of traffic measurements available over which to perform such analysis, processing and storage is overwhelming. For this reason, the research community has understood the importance of finding an effective mechanism to reduce (or subsample) such huge amount of data, with minimum loss of information. More specifically, this work considers the traffic volume traversing a given router per unit of time, which can be obtained by periodically polling the counters of the interfaces table via SNMP. We further propose a mechanism to downsample such traffic time-series using multi-resolution analysis with wavelets, and evaluate the optimal subsampling level based on comparing the queueing behavior of the subsampled and original signals at the output of a router. This mechanism is more related to network performance than conventional comparison levels, since queueing delay is a very representative QoS metric. The method presented in this paper has been applied to an extensive set of real measurements collected from RedlRIS, the Spanish National Research Network. The results show that it is possible to reduce the data to one fourth of its original size for the traffic generated by most analyzed universities, and even to one eighth for data collected from routers with more aggregated traffic, both with a high level of confidence.\",\n \"Title: Evaluation of preemption probabilities in OBS networks with burst segmentation.\\nYear: 2005\\n\\nAbstract: Preemption techniques have been recently proposed for service differentiation in Optical Burst Switching (OBS) networks. According to [1], an incoming burst with the same priority that the burst in service will preempt the wavelength if the residual length of the burst in service is smaller than the incoming burst transmission time. For a network scenario with no wavelength conversion, the preemption probability is evaluated assuming Exponential, Gaussian and Pareto-distributed burst sizes. Knowledge of the preemption dynamics at an OBS switch is a fundamental issue in performance evaluation, since the downstream switches will surely be affected. An analytical upper bound is provided, that shows that the preemption probability depends on the burst size distribution, which in turn depends on the burst assembly technique used at the network edges. On the other hand, not only truncated bursts result from preemption, as reported in other studies, but also the burst size distribution for preempting bursts is shifted to larger values.\",\n \"Title: Automated Detection of Load Changes in Large-Scale Networks\\nYear: 2009\\n\\nAbstract: This paper presents a new online algorithm for automated detection of load changes, which provides statistical evidence of stationary changes in traffic load. To this end, we perform continuous measurements of the link load, then look for clusters in the dataset and finally apply the Behrens-Fisher hypothesis testing methodology. The algorithm serves to identify which links deviate from the typical load behavior. The rest of the links are considered normal and no intervention of the network manager is required. Due to the automated selection of abnormal links, the Operations Expenditure (OPEX) is reduced. The algorithm has been applied to a set of links in the Spanish National Research and Education Network (RedIRIS) showing good results.\",\n \"Title: Performance Issues in Optical Burst/Packet Switching\\nYear: 2009\\n\\nAbstract: This chapter summarises the activities on optical packet switching (OPS) and optical burst switching (OBS) carried out by the COST 291 partners in the last 4 years. It consists of an introduction, five sections with contributions on five different specific topics, and a final section dedicated to the conclusions. Each section contains an introductive state-of-the-art description of the specific topic and at least one contribution on that topic. The conclusions give some points on the current situation of the OPS/OBS paradigms.\",\n \"Title: A Bayesian decision theory approach for the techno-economic analysis of an all-optical router (extended version)\\nYear: 2008\\n\\nAbstract: Typically, core networks are provided with both optical and electronic physical layers. However, the interaction between the two layers is at present limited, since most of the traditional transport functionalities, such as traffic engineering, switching and restoration, are carried in the IP/MPLS layer. In the light of this, the research community has paid little attention to the potential benefits of the interaction between layers, multilayer capabilities, on attempts to improve quality of service control. This paper shows when to move incoming label switched paths (LSPs) between layers based on a multilayer mechanism that trades off a QoS metric, such as end-to-end delay, and techno-economic aspects. Such a mechanism follows the Bayesian decision theory, and is tested with a set of representative case scenarios.\",\n \"Title: On the blocking time distribution of core OBS switches\\nYear: 2009\\n\\nAbstract: Given the bufferless nature of Optical Burst- Switched networks, data bursts are either transmitted or dropped; the latter\\n typically occurs when all the wavelengths of a given output port are occupied. Clearly, the amount of time during which a\\n given output port is blocked and cannot schedule incoming data bursts is a key performance measure of OBS networks. This work\\n shows that, under Poissonian burst arrivals, the blocking time distribution of a given output port in an OBS node approaches\\n the exponential distribution as the number of wavelengths increases. It is further shown that this behavior remains regardless\\n of the size distribution of incoming bursts, and therefore, regardless of the burst-assembly algorithms employed at the border\\n nodes. Finally, this result is also applied to the characterization of the amount of overspill traffic, that is, the number\\n of bursts that arrive within a blocked period, and therefore must be either dropped or diverted over alternative routes.\",\n \"Title: Reliable Network Management Tool through Internet\\nYear: 1999\\n\\nAbstract: This paper presents a number of issues which are relevant to the development of network management tools based on Web interfaces. Specifically, the following technologies for the network management console a re evaluated: HTML, HTML/Java and Tcl/Tk. The pros and cons of the abovementioned technologies are discussed in terms of reliability, probe/console transmision delay, CPU use, data processing and alarm reception capabilities. To do so, we analyze the implementation issues of a novel network management tool, PROMIS, which performs traffic monitoring functions with information collected from a number of network probes.\",\n \"Title: On the impact of packet sampling on Skype traffic classification.\\nYear: 2013\\n\\nAbstract: Nowadays, traffic classification technology addresses the exciting challenge of dealing with ever-increasing network speeds, which implies more computational load especially when on-line classification is required, but avoiding to reduce classification accuracy. However, while the research community has proposed mechanisms to reduce load, such as packet sampling, the impact of these mechanisms on traffic classification has been only marginally studied. This paper addresses such study focusing on Skype application given its tremendous popularity and continuous expansion. Skype, unfortunately, is based on a proprietary design, and typically uses encryption mechanisms, making the study of statistical traffic characteristics and the use of Machine Learning techniques the only possible solution. Consequently, we have studied Skypeness, an open-source system that allows detecting Skype at multi-10Gb/s rates applying such statistical principles. We have assessed its performance applying different packet sampling rates and policies concluding that classification accuracy is significantly degraded when packet sampling is applied. Nevertheless, we propose a simple modification in Skypeness that lessens such degradation. This consists in scaling the measured packet interarrivals used to classify according to the sampling rate, which has resulted in a significant gain.\",\n \"Title: Discrete-time heavy-tailed chains, and their properties in modeling network traffic\\nYear: 2007\\n\\nAbstract: The particular statistical properties found in network measurements, namely self-similarity and long-range dependence, cannot be ignored in modeling network and Internet traffic. Thus, despite their mathematical tractability, traditional Markov models are not appropriate for this purpose, since their memoryless nature contradicts the burstiness of transmitted packets. However, it is desirable to find a similarly tractable model which is, at the same time, rigorous at capturing the features of network traffic. This work presents discrete-time heavy-tailed chains, a tractable approach to characterize network traffic as a superposition of discrete-time “on/off” sources. This is a particular case of the generic “on/off” heavy-tailed model, thus shows the same statistical features as the former, particularly self-similarity and long-range dependence, when the number of aggregated sources approaches infinity. The model is then applicable to characterize a number of discrete-time communication systems, for instance, ATM and optical packet switching, to further derive meaningful performance metrics such as average burst duration and the number of active sources in a random instant.\",\n \"Title: An information model for the management of Optical Burst Switched networks\\nYear: 2007\\n\\nAbstract: The optical burst switching (OBS) paradigm proposes a new set of transmission protocols and network architectures that permits the high-utilization of the raw bandwidth available by dense wavelength division multiplexing at a moderate computational cost. Accordingly, it is necessary to extend the management plane of such networks to include the particular aspects of OBS, in order to guarantee the appropriate network operation. This paper analyzes the information required for the management of such OBS networks and proposes a new information model based on observed management use-cases. A simple data model is also specified to reduce the computational burden, but compliant with the modeled information.\",\n \"Title: Virtualization of reconfigurable coprocessors in HPRC systems with multicore architecture\\nYear: 2012\\n\\nAbstract: HPRC (High-Performance Reconfigurable Computing) systems include multicore processors and reconfigurable devices acting as custom coprocessors. Due to economic constraints, the number of reconfigurable devices is usually smaller than the number of processor cores, thus preventing that a 1:1 mapping between cores and coprocessors could be achieved. This paper presents a solution to this problem, based on the virtualization of reconfigurable coprocessors. A Virtual Coprocessor Monitor (VCM) has been devised for the XtremeData XD2000i In-Socket Accelerator, and a thread-safe API is available for user applications to communicate with the VCM. Two reference applications, an IDEA cipher and an Euler CFD solver, have been implemented in order to validate the proposed architecture and execution model. Results show that the benefits arising from coprocessor virtualization outperform its overhead, specially when code has a significant software weight.\",\n \"Title: A FPGA-based scalable architecture for URL legal filtering in 100GbE networks\\nYear: 2012\\n\\nAbstract: Legal filtering is common practice in many countries to avoid access to websites with criminal or violent content. This kind of filtering is typically implemented at the edge routers of ISP's core networks, so it is mandatory to support very high bit rates. This paper proposes a hardware-software solution based on FPGAs, which scales up to 100 Gbps Ethernet. A FPGA-based PCIe board equipped with two network interfaces is used to intercept ISP traffic. The FPGA performs an initial filtering of the packets whose destination is potentially forbidden, based on a hash of the destination IP address. Filtered packets are sent to the software application, which inspects them and decides if the URL is actually forbidden or not. This two-level filtering allows for the scalability of the proposed solution to very high bit rates, not only because it simplifies FPGA design, but also because it significantly reduces software load, since potentially forbidden destinations are few. Additionally, this solution adds a minimal latency to most of the packets, and also allows for updating filtering rules without interrupting ISP traffic. The paper presents a proof-of-concept 10GbE implementation of the proposed architecture, as well as an analysis of its scalability up to 100GbE.\",\n \"Title: A Tool For Solving Differential Games With Co-Evolutionary Algorithms\\nYear: 1999\\n\\nAbstract: Game theory is concerned with optimization problems involving several players with conflicting interests. Differential games are an interesting area inside this field in which the problem is formulated by means of dynamical systems. In spite that the theoretical solution of differential games is well known, faced with large-scale, complex systems, analytical or, even, numerical methods are not usually suitable. Genetic algorithms appear to be useful for solving such problems when dealing with nonlinear, large-scale systems. This paper shows how co-evolutionary algorithms can be applied to solve differential games and presents a computer tool to formulate and solve these problems. The differential equations which define the system under study are written in Vensim, a visual modeling tool. The usefulness of the presented tool is shown by means of two examples.\",\n \"Title: Packet Video Broadcasting with General-Purpose Operating Systems in an Ethernet\\nYear: 2004\\n\\nAbstract: Video transmission with general-purpose PCs poses a number of requirements that radically differ from those of high-end dedicated video servers. We analyze the scenario of an Ethernet local area network in which a number of PCs are transmitting video streams, while other TCP/IP applications are also running concurrently. Our findings show that since the operating system clock resolution cannot cope with the transmission timing requirements the following holds: if the video transmission is performed with exact timing accuracy to maintain a constant rate then CPU load grows to 100%, thus blocking the PC for other user applications; on the other hand, if transmission is performed in a bursty manner, i.e. with sleep system calls, then CPU load decreases dramatically but the increased burstiness of the video stream has a negative impact on network performance (for example, capture effect in the Ethernet). Furthermore, the impact of video transmission over the rest of TCP/IP applications running on the same network depends heavily on the packet size. We provide an integrated analysis of operating system and network parameters to achieve video broadcasting while preserving timing requirements and minimizing the impact on other applications.\",\n \"Title: PROMIS: A Reliable Real-Time Network Management Tool for Wide Area Networks\\nYear: 1998\\n\\nAbstract: This paper presents the PROMIS tool, new network management tool based on a distributed architecture of traffic probes. PROMIS allows authorized users to monitor traffic from any WAN segment using a WWW console or a Tcl/Tk graphic interface. In contrast to current network monitoring platforms based in SNMP (Simple Network Management Protocol) or RMON (Remote network MONitor), PROMIS is based on an optimized software architecture that usesa reliable transport protocol (TCP) to provide lossless transmision of monitoring information, thus allowing for real-time monitoring irrespective of network load.\",\n \"Title: Wire-speed statistical classification of network traffic on commodity hardware\\nYear: 2012\\n\\nAbstract: In this paper we present a software-based traffic classification engine running on commodity multi-core hardware, able to process in real-time aggregates of up to 14.2 Mpps over a single 10 Gbps interface -- i.e., the maximum possible packet rate over a 10 Gbps Ethernet links given the minimum frame size of 64 Bytes. This significant advance with respect to the current state of the art in terms of achieved classification rates are made possible by:(i) the use of an improved network driver, PacketShader, to efficiently move batches of packets from the NIC to the main CPU;(ii) the use of lightweight statistical classification techniques exploiting the size of the first few packets of every observed flow;(iii) a careful tuning of critical parameters of the hardware environment and the software application itself.\",\n \"Title: Factor Analysis Of Internet Traffic Destinations From Similar Source Networks\\nYear: 2012\\n\\nAbstract: Purpose - This study aims to assess whether similar user populations in the Internet produce similar geographical traffic destination patterns on a per-country basis.Design/methodology/approach - The authors collected a country-wide NetFlow trace, which encompasses the whole Spanish academic network. Such a trace comprises several similar campus networks in terms of population size and structure. To compare their behaviors, the authors propose a mixture model, which is primarily based on the Zipf-Mandelbrot power law to capture the heavy-tailed nature of the per-country traffic distribution. Then, factor analysis is performed to understand the relation between the response variable, number of bytes or packets per day, with dependent variables such as the source IP network, traffic direction, and country.Findings - Surprisingly, the results show that the geographical distribution is strongly dependent on the source IP network. Furthermore, even though there are thousands of users in a typical campus network, it turns out that the aggregation level which is required to observe a stable geographical pattern is even larger.Practical implications - Based on these findings, conclusions drawn for one network cannot be directly extrapolated to different ones. Therefore, ISPs' traffic measurement campaigns should include an extensive set of networks to cope with the space diversity, and also encompass a significant period of time due to the large transient time.Originality/value - Current state of the art includes some analysis of geographical patterns, but not comparisons between networks with similar populations. Such comparison can be useful for the design of content distribution networks and the cost-optimization of peering agreements.\",\n \"Title: On the real impact of Path Inflation in networks under production\\nYear: 2012\\n\\nAbstract: The research community has proved the existence and studied the root causes of Path Inflation on the Internet - end-to-end paths significantly longer than necessary. However, it has been typically ignored that the popularity of traffic destinations and, consequently, of network paths, is clearly heterogeneous - some destinations are popular while others are barely accessed. In this paper, we propose a trace-driven methodology to measure the Path Inflation accounting for the popularity of Internet destinations from a given network, thus evaluating the implications that Path Inflation exerts on real networks under production. This information is important for network operators because it allows them to objectively stand out those destinations whose connection analysis must be prioritized. The results of applying this methodology to the Spanish academic network show that the most critical regions to focus on are Spain's closest countries, which either are very popular or have large Path Inflation as a consequence of the use of transatlantic links as intermediate nodes, or both.\",\n \"Title: On capacity planning for the GMPLS network control plane\\nYear: 2008\\n\\nAbstract: This article presents capacity planning rules for the control plane of all-optical networks featuring GMPLS and RSVP-TE as\\n a connection setup protocol. As per RSVP standard, a refresh message mechanism is incorporated to RSVP such that the state\\n is periodically refreshed on a link per link basis. We provide analytical expressions for the bandwidth and buffer sizes to\\n be provided such that no flows are torn down due to lack of refresh messages. Our findings show that small buffers (several\\n KBytes) suffice to sustain the signaling load for as much as 400 RSVP flows per link, with the simplest RSVP refresh mechanism\\n (neither using link bundling nor acknowledgments). On the other hand, we also find the packet drop probability per link for\\n a given network topology for the case that the flow survival probability is larger than a given threshold. We provide numerical\\n examples based on the COST 239 european network topology and real RSVP traffic traces from early-commercial switching equipment.\",\n \"Title: High-Level Languages and Floating-Point Arithmetic for FPGA-Based CFD Simulations\\nYear: 2011\\n\\nAbstract: Editor's note:Computational fluid dynamics is a classical problem in high-performance computing. In order to make use of an existing code base in this field, the use of high-level design tools is an imperative. The authors explore the use of the Impulse C design tools for a Navier-Stokes implementation.—George A. Constantinides (Imperial College London) and Nicola Nicolici (McMaster University)\",\n \"Title: High-accuracy network monitoring using ETOMIC testbed\\nYear: 2011\\n\\nAbstract: Obtaining an accurate picture of what is happening inside the Internet can be particularly challenging using end-to-end measurements. The ability to make high-precision timing measurements (one-way delay, interarrival times, ...) using probe packets is key to attain a clear picture of network performance. The European Traffic Observatory Measurement Infrastructure (ETOMIC) is a high-precision measurement infrastructure, distributed throughout Europe. With the ANME (Advanced Network Monitoring Equipment) boxes and their related software, ETOMIC offers users a versatile monitoring solution that performs both active and passive measurements to a very high level of precision.\",\n \"Title: Analysis of the backing up fuzzy control of truck-trailers using the qualitative theory of dynamic systems.\\nYear: 2001\\n\\nAbstract: Abstract,the vehicle position givand the trailer orientation ,\",\n \"Title: An Approximation of The Dynamics of Time-Delay Systems with Implications in Simulation and Analysis\\nYear: 1998\\n\\nAbstract: A fast convergent approximation of the dynamics of a system with time delays is proposed. Such an approximation is developed in the time-domain and has a matrix representation that is affine in the magnitude of the delay tau. This affine dependence on tau allows a subsequent analysis of the robustness of the system using LMI approaches.\",\n \"Title: Measurements and Measurement Tools in OpenLab: Use Cases with Measurement Data Ontologies.\\nYear: 2012\\n\\nAbstract: In this chapter we review the network measurement tools and instruments that are in place in the FP7 OpenLab project, which provides a set of different network testbeds. We also focus on the problem of data heterogeneity, which comes from the fact that different measurement tools will provide data in different formats and structured in different ways. Therefore, a common information model becomes necessary and the OpenLab ontology-based solution is presented. Such ontology is being standardized by an Industry Specification Group at ETSI, resulting in the first ever standard on network measurement data ontologies.\",\n \"Title: Describing function method for stability analysis of PD and PI fuzzy controllers\\nYear: 2004\\n\\nAbstract: A fuzzy logic controller saturates outside the universe of discourse region. This saturation gives rise to a universal nonlinearity for this type of controller. In this paper, the effects of this nonlinearity are analyzed for the most usual fuzzy controllers: PD and PI fuzzy controllers. It is shown that due to this saturation some pathological behaviors such as oscillations or unstable limit cycles can occur. The methodology employed in the analysis is based on the describing function, which is determined for PD and PI fuzzy controllers. One example illustrates the relevance of the proposed methodology.\",\n \"Title: Bifurcation Analysis Of A Rotating Arm With Saturated Hamiltonian Control Laws\\nYear: 2005\\n\\nAbstract: The actuator saturation effects on the global state space structure of a rotating arm with a Hamiltonian control law are studied via bifurcation analysis. In addition to other well-known codimension-two bifurcation points, some saturation-induced \\\"fan-like\\\" bifurcation points are detected. The dynamical complexity found in this seemingly simple example is remarkable.\",\n \"Title: Network monitoring for energy efficiency in large-scale networks: the case of the Spanish Academic Network.\\nYear: 2012\\n\\nAbstract: Abstract The energy consumption due to information technologies is large and there are many ongoing efforts to cut it down. Previous studies have shown that there is a significant percentage of hosts which are left switched on in office buildings at night and weekend, whose energy consumption is significant. This motivates the development of techniques that can detect switched-on hosts in a simple and scalable way. This paper proposes detection techniques based on network traffic monitoring. The results show that such techniques can effectively detect switched-on hosts in small-medium campus networks and also in large country-wide networks that serve more than one million users. Interestingly, the proposed techniques can be implemented using the existing network monitoring infrastructure, specially for large networks, at a negligible additional investment.\",\n \"Title: Assembly admission control based on random packet selection at border nodes in Optical Burst-Switched networks\\nYear: 2009\\n\\nAbstract: In Optical Burst-Switched (OBS) networks employing Just Enough Time (JET) signalling, Burst-Control Packets request resources\\n at intermediate nodes following a one-way reservation protocol, that is, requested resources are not confirmed back to the\\n source. Hence, data bursts are transmitted without any guarantees, and it sometimes occurs that these are dropped at a certain\\n hop in the source–destination path, hence wasting resources at previous hops. This effect is specially harmful if some connections\\n are abusing of the global shared resources, violating their respective Service Level Agreements, thus causing: (1) global\\n performance degradation; and, (2) unfair service received by other connections. This article proposes “Random Packet Assembly\\n Admission Control”, an admission control mechanism for OBS networks that moderates the two problems above. The mechanism monitors\\n the network load status, detects which links are heavily loaded and decides which flows among the total traversing them require\\n throughput decrease, on attempts to alleviate congestion and benefit other flows which are not abusing from the network. Such\\n throughput decrease consists of preventive packet dropping during the assembly process at the ingress nodes of the OBS network,\\n thus making no use of the network core. The numerical results show a substantial increase in the throughput experienced by\\n well-behaved flows, and fundamental fairness achievement in the use of optical resources.\",\n \"Title: Analysis of average burst-assembly delay and applications in proportional service differentiation\\nYear: 2007\\n\\nAbstract: In Optical Burst-Switched (OBS) networks, the limitation of optical buffering devices make it impractical to deploy conventional\\n delay-based differentiation algorithms such as Active Queue Management, Weighted Fair Queuing, etc. Furthermore, only the\\n delay that appears due to the burst-assembly process constitutes a variable quantity (all the other sources of delay are mostly\\n fixed), it is then reasonable to make use of the burst-assembly algorithm to provide class-based delay differentiation. The\\n aim of the following study is twofold: first it defines an average assembly delay metric, which represents the assembly delay\\n experienced by a random arrival at the burst assembler of an edge OBS node; and second, this metric is used to define and\\n configure a two-class burst-assembly policy, which gives preference to high-priority traffic over low-priority packet arrivals.\\n The results show that, (1) tuning the parameters of the two-class assembly algorithm, the two classes of traffic exhibit different\\n burst-assembly delay; and, (2) such parameters can be adjusted to provide a given differentiation ratio in the light of the\\n proportional QoS differentiation approach proposed in the literature. A detailed analysis of the two-class assembly algorithm\\n is given, along with an exhaustive set of experiments and numerical examples that validate the equations derived.\",\n \"Title: Bridging the gap between hardware and software open source network developments\\nYear: 2014\\n\\nAbstract: The rise of network speeds to tens of gigabits per second poses a challenge to develop packet processing applications that can cope with such bit rates. Therefore, the need for a suitable open source system that can be used as a prototype platform to test new network functionality while ensuring line-rate processing, accurate timestamping, and reduced power consumption has become evident. All these requirements cannot be achieved by using software-only solutions, but rather with hardware-based platforms such as NetFPGA. The main obstacle when using this type of open source FPGA-based solution is the cost of development, in both time and hardware development skills required. The spread of new circuit synthesis tools using high-level languages opens the door for the development of hardware-based networking applications with reasonable development effort, compared to the use of traditional hardware description languages. In this article, we describe how existing open source hardware-based platforms for networking applications will be fueled by the change in the programming model of FPGAs provided by modern high-level synthesis tools. For this, we implemented a network flow monitor using high-level languages and compared the effort spent with respect to a traditional hardware development cycle. Preliminary results are very promising, given that development time is reduced from months to weeks.\",\n \"Title: Multi-Granular, Multi-Purpose And Multi-Gb/S Monitoring On Off-The-Shelf Systems\\nYear: 2014\\n\\nAbstract: As an attempt to make network managers' life easier, we present M(3)Omon, a system architecture that helps to develop monitoring applications and perform network diagnosis. M(3)Omon behaves as an intermediate layer between the traffic and monitoring applications that provides advanced features, high performance and low cost. Such advanced features leverage a multi-granular and multi-purpose approach to the monitoring problem. Multi-granular monitoring provides answers to tasks that use traffic aggregates to identify an event, and requires either flow records or packet data or even both to understand it and, eventually, take convenient countermeasures. M(3)Omon provides a simple API to access traffic simultaneously at several different granularities, i.e. packet-level, flow-level and aggregate statistics. The multi-purposed design of M(3)Omon allows not only performing tasks in parallel that are specifically targeted to different traffic-related purposes (e.g. traffic classification and intrusion detection) but also sharing granularities between applications, e.g. several concurrent applications fed from flow records that are provided by M(3)Omon. Finally, the low-cost characteristic is brought by off-the-shelf systems (the combination of open-source software and commodity hardware) and the high performance is achieved thanks to modifications in the standard NIC driver, low-level hardware interaction, efficient memory management and programming optimization. Copyright (C) 2014 John Wiley & Sons, Ltd\",\n \"Title: EFMP - a new congestion control mechanism for flow-aware networks\\nYear: 2014\\n\\nAbstract: AbstractIn this paper, a new congestion control mechanism for flow-aware networks, that is, enhanced flushing mechanism with priority EFMP is introduced. Proposed by J. Roberts and S. Oueslati in 2004, flow-aware networking is a concept that ensures quality of service in networks based on flows. EFMP improves the efficiency of transmission in FAN by introducing new policies in the admission control block of a cross-protect router. The mechanism is thoroughly described, analysed, and validated through simulations. The proposed mechanism inherits the advantages of previously known admission control schemes while ensuring fast acceptance times of new streaming flows and proper transmission of the remaining traffic. Moreover, the comparison with the multilayer flow-aware networks architecture shows that EFMP ensures better performance and lower cost of transmission in a network with limited resources. Copyright © 2013 John Wiley & Sons, Ltd.\",\n \"Title: Packet Storage at Multi-gigabit Rates Using Off-the-Shelf Systems\\nYear: 2014\\n\\nAbstract: The use of closed solutions from most known vendors to carry out network-monitoring tasks has turned out to be a questionable option given their lack of flexibility and extensibility, which has typically been translated into higher costs. Consequently, we study whether high-performance monitoring tasks can be carried out using off-the-shelf systems, the alternative to these pitfalls from the research community, consisting in the combination of open-source software and commodity hardware. We focus on sniffing and storing network traffic as one of the major tasks in any monitoring architecture. Specifically, we first review the keys to sniff traffic at multi-gigabit rates, and then present an experimental evaluation of commodity hard drives. Finally, the lessons learned from such studies and the performed experiments have conducted us to the development of an open solution, namely text[HPCAP], which sniffs and stores multi-gigabit traffic using commodity hardware without packet losses in very demanding scenarios.\",\n \"Title: TNT10G: A high-accuracy 10 GbE traffic player and recorder for multi-Terabyte traces\\nYear: 2014\\n\\nAbstract: In this paper we present TNT10G (multi-Terabyte trace Network Tester), an FPGA-based tool for replaying and capturing massive Ethernet traces at 10 Gb/s. The tool is capable of reproducing and storing terabytes of network traffic at line rate, even if small packets are being used. Moreover, since the design works at low level (XGMII), accuracy is better than 10 ns, and it is also possible to observe and generate anomalous conditions, such as malformed frames, FCS errors, or illegal inter-frame gaps. All such features make TNT10G a truly useful tool for network testing and monitoring at 10 Gb/s. The design uses the NetFPGA-10G platform, although it could be easily ported to other boards since it uses standard AXI buses. The key element to achieve line-rate operation is a custom-developed Linux driver, which works in conjunction with a high-speed DMA backend core from Northwest Logic. Such blocks, together with a RAID0 array of commodity SSD disks, enable operation at 10 Gb/s. Finally, the use of a low-cost academic board together with off-the-shelf components allows for an open, extensible and cost-effective solution, a unique combination not found in commercial products.\",\n \"Title: Selective Capping of Packet Payloads for Network Analysis and Management.\\nYear: 2015\\n\\nAbstract: Both network managers and analysts appreciate the importance of network traces as a mechanism to understand traffic behavior, detect anomalies and evaluate performance in a forensic manner, among other applications. Unfortunately, the process of network capture and storage has become a challenge given the ever-increasing network speeds. In this scenario, we intend to make packets thinner to reduce both write speed and storage requirements on hard-drives and further reduce computational burden of packet analysis. To this end, we propose to remove the payload on those packets that hardly could be interpreted afterwards. Essentially, binary packets from unknown protocols fall into this category. On the other hand, binary packets from well-known protocols and protocols with some ASCII data are fully captured as potentially a network analyst may desire to inspect them. We have named this approach as selective capping, which has been implemented and integrated in a high-speed network driver as an attempt to make its operation faster and more transparent to upper layers. Its results are promising as it achieves multi-Gb/s rates in different scenarios, which could be further improved exploiting novel low-level hardware-software tunings to meet the fastest networks' rates.\",\n \"Title: Jitter-based analysis and discussion of burst assembly algorithms\\nYear: 2006\\n\\nAbstract: This work provides a jitter analysis of size-based burst assembly algorithms and also discusses other burst assem- bly algorithms that use the packet delay as the assembly threshold to provide a bound on jitter.\",\n \"Title: Quality of Service analysis of Internet links with minimal information\\nYear: 2013\\n\\nAbstract: Monitoring the Quality of Service (QoS) of Internet links is of paramount importance for network managers, and consequently has received great attention from the research community. To monitor QoS, practitioners leverage on network traffic measurements and, by means of practical models and statistical techniques, make predictions and detect outliers that allow the planning of telecommunication networks and detection of abnormal behavior, respectively. However, obtaining detailed measurements from Internet links at current network speeds is very challenging. Moreover, the amount of resources required to properly storage detailed network measurements make unfeasible to perform long measurement campaigns. These facts have motivated the application of techniques to reduce the information gathered from the network, such as sampling or the use of summarized statistics, making network traffic monitoring less demanding and allowing longer measurement campaigns. Accordingly, this thesis proposes two novel methodologies to perform QoS analysis of Internet links leveraging on summarized statistics of network traffic. Each methodology relies on a network traffic model, on which sound statistical methodologies are used on attempts of detecting relevant events that either require action from the network managers or are related with degradations of the provided QoS.\",\n \"Title: Accurate and flexible flow-based monitoring for high-speed networks\\nYear: 2013\\n\\nAbstract: In this paper we present an FPGA-based architecture to export flows in 10 Gbps networks, implemented on the NetFPGA-10G platform. Flow-based monitoring is a powerful methodology to analyze and detect network issues, such as congested links or DDoS attacks. Our design provides the following advantages: (i) The architecture allows processing 10 Gbps links without sampling, even for the highest packet rate of 14.88 Mpps (Million packets per second) that corresponds to the shortest (64-byte) Ethernet frames; (ii) It is possible to manage up to 786,432 concurrent flows; (iii) The project is developed in an open-source hardware platform and the HDL code is open to the community; (iv) The proposed approach frees network routers from the burden of exporting flows.\",\n \"Title: Testing the capacity of off-the-shelf systems to store 10GbE traffic.\\nYear: 2015\\n\\nAbstract: The maturity of the telecommunications market and the fact that user demands increase every day leaves network operators no option but to deploy high-speed infrastructures and test them in an efficient and economical manner. A common approach to this problem has been the storage of network traffic samples for analysis and replay using different versions of what we have named NTSS. This type of tas...\",\n \"Title: Accurate and affordable packet-train testing systems for multi-gigabit-per-second networks\\nYear: 2016\\n\\nAbstract: Communication networks these days face a relentless increase in traffic load. Multi-gigabitper- second links are becoming widespread, and network devices are under continuous stress, so testing whether they guarantee the specified throughput or delay is a must. Software-based solutions, such as packet-train traffic injection, were adequate for lower speeds, but they have become inaccurate in the current scenario. Hardware-based solutions have proved to be very accurate, but usually at the expense of much higher development and acquisition costs. Fortunately, new affordable FPGA SoC devices, as well as high-level synthesis tools, can very efficiently reduce these costs. In this article we show the advantages of hardware-based solutions in terms of accuracy, comparing the results obtained in an FPGA SoC development platform and in NetFPGA-10G to those of software. Results show that a hardware-based solution is significantly better, especially at 10 Gb/s. By leveraging high-level synthesis and open source platforms, prototypes were quickly developed. Noticeable advantages of our proposal are high accuracy, competitive cost with respect to the software counterpart, which runs in high-end off-the-shelf workstations, and the capability to easily evolve to upcoming 40 Gb/s and 100 Gb/s networks.\",\n \"Title: Local Bifurcation Analysis In The Furuta Pendulum Via Normal Forms\\nYear: 2000\\n\\nAbstract: Inverted pendulums are very suitable to illustrate many ideas in automatic control of nonlinear systems. The rotational inverted pendulum is a novel design that has some interesting dynamics features that are not present in inverted pendulums with linear motion of the pivot. In this paper the dynamics of a rotational inverted pendulum has been studied applying well-known results of bifurcation theory. Two classes of local bifurcations are analyzed by means of the center manifold theorem and the normal form theory - first, a pitchfork bifurcation that appears for the open-loop controlled system; second, a Hopf bifurcation, and its possible degeneracies, of the equilibrium point at the upright pendulum position, that is present for the controlled closed-loop system. Some numerical results are also presented in order to verify the validity of our analysis.\",\n \"Title: Modification Via Averaging Of Partial-Energy-Shaping Control For Creating Oscillations: Cart-Pendulum Example\\nYear: 2009\\n\\nAbstract: We consider the challenging problem of creating oscillations in underactuated mechanical systems. Target oscillatory motions of the indirectly actuated degree of freedom of a mechanical system can often be achieved via a straightforward to design feedback transformation. Moreover, the corresponding part of the dynamics can be forced to match a desired second-order system possessing the target periodic solution (Aracil, J., Gordillo, F., and Acosta, J.A. (2002), 'Stabilization of Oscillations in the Inverted Pendulum', in Proceedings of the 15th IFAC World Congress, Barcelona, Spain; Canudas-de-Wit, C., Espiau, B., and Urrea, C. (2002), 'Orbital Stabilisation of Underactuated Mechanical Systems', in Proceedings of the 15th IFAC World Congress, Barcelona, Spain). Sometimes, it is possible to establish the presence of periodic or bounded motions for the remaining degrees of freedom in the transformed system. However, typically this motion planning procedure leads to an open-loop unstable orbit and by necessity should be followed by a feedback control design. We propose a new approach for synthesis of a (practically) stabilising feedback controller, which ensures convergence of the solutions of the closed-loop system into a narrow tube around the preplanned orbit. The method is illustrated in detail by shaping oscillations in the inverted pendulum on a cart around its upright equilibrium. The complete analysis is based on application of a non-standard higher-order averaging technique assuming sufficiently high frequency of oscillations and is presented for this particular example.\",\n \"Title: Proposal of a new information theory-based technique based on traffic anomaly detection analysis\\nYear: 2015\\n\\nAbstract: The change-point detection theory is used to identify abrupt changes in the network traffic. The literature has focused on longitudinal traffic analysis, namely, detecting sudden peak changes, rather than analysing the traffic pattern on a 24 h typical day. As traffic varies throughout the day, it is essential to consider the concrete traffic period in which the anomaly occurs, which is useful for checking interconnection agreements amongst operators, something not possible with traditional sudden peak changes techniques. The aim of this paper is to analyse how the different algorithms behave in detecting changing points inside a typical day profile. We conclude that a combination of the algorithms provides better results than the use of a single one: in low traffic periods the tests of goodness-of-fit best detect changing conditions, while in normal traffic periods daytime entropy-based algorithms best detect traffic increases; besides, the statistical control charts complements both of them when detecting very abrupt changes regardless of the traffic load.\",\n \"Title: Commodity Packet Capture Engines: tutorial, cookbook and applicability\\nYear: 2015\\n\\nAbstract: Users’ demands have dramatically increased due to widespread availability of broadband access and new Internet avenues for accessing, sharing and working with information. In response, operators have upgraded their infrastructures to survive in a market as mature as the current Internet. This has meant that most network processing tasks (e.g., routing, anomaly detection, monitoring) must deal with challenging rates, challenges traditionally accomplished by specialized hardware — e.g., FPGA. However, such approaches lack either flexibility or extensibility —or both. As an alternative, the research community has proposed the utilization of commodity hardware providing flexible and extensible cost-aware solutions, thus entailing lower operational and capital expenditure investments. In this scenario, we explain how the arrival of commodity packet engines has revolutionized the development of traffic processing tasks. Thanks to the optimization of both NIC drivers and standard network stacks and by exploiting concepts such as parallelism and memory affinity, impressive packet capture rates can be achieved in hardware valued at a few thousand dollars. This tutorial explains the foundation of this new paradigm, i.e., the knowledge required to capture packets at multi-Gb/s rates on commodity hardware. Furthermore, we thoroughly explain and empirically compare current proposals, and importantly explain how apply such proposals with a number of code examples. Finally, we review successful use cases of applications developed over these novel engines.\",\n \"Title: p‐Cycle configuration possibilities over DRDA networks\\nYear: 2015\\n\\nAbstract: A resilience analysis of protection cycles (p-cycle) configurations for Double Rings with Dual Attachment (DRDAs) architectures is presented in this work. DRDAs are composed of two rings with corresponding nodes connected by two separated links. There are several possible configurations of p-cycles, which may be used in DRDAs for improving link or node protection upon link failure. The values of the parameters Mean Time To Failure and Mean Time To Disconnection are analysed in the paper to show the best choice of p-cycles in DRDAs architectures. Copyright (c) 2014 John Wiley & Sons, Ltd.\",\n \"Title: Leveraging open source platforms and high-level synthesis for the design of FPGA-based 10 GbE active network probes\\nYear: 2015\\n\\nAbstract: Nowadays, 10 Gb/s networks are becoming more and more widespread. Consequently, there is an increasing need for testing equipment for those networks, to measure parameters such as throughput, delay, jitter, packet loss rate, etc. Network testing equipment can be either active or passive, depending on whether it injects traffic or simply monitors packets in network links. In this paper we focus on active network probes, particularly those which are based on injection of packet trains. This type of probes have the advantage of causing little interference with existing network traffic, even though they are quite effective to measure several network parameters such as throughput or delay. Here, we take advantage of the open source NetFPGA project to implement a 10 GbE active monitoring probe based on the packet-train technique. In order to reduce development time, we used NetFPGA's OSNT (Open Source Network Tester) monitor project as a starting point, and we also used high-level synthesis tools (namely, Vivado-HLS) to implement the IP core in charge of computing network parameters. Such two design strategies turned out to be very effective both in terms of coding productivity and accuracy of measurements. Actually, the quality of measurements was found to be much better than that obtained with software solutions running on commodity servers, though the development effort was not significantly higher, thanks to the use of open source platforms and high-level synthesis techniques.\",\n \"Title: Selective Capping of Packet Payloads at Multi-Gb/s Rates.\\nYear: 2016\\n\\nAbstract: Network managers and analysts are well aware of the importance of network traces to understand traffic behavior, detect anomalies, and evaluate performance forensically, among others. However, the storage required for traffic traces has greatly expanded due to increasing network speeds. In this paper, we selectively cap the packet payload to reduce write speed and storage requirements on hard drives and further reduce the computational burden of packet analysis. The proposed techniques take advantage of most packet payloads being useless for analysis purposes, because they are either encrypted or in a proprietary application non-readable format. Conversely, non-ASCII packets from well-known protocols and protocols with some ASCII data are fully captured as they may be potentially useful for network analysis. We have named this approach as selective capping, and we have implemented and integrated it into a high-speed network driver and a software module at user level, to make its operation more transparent and faster to upper layer applications. The results are promising, and selective capping achieves multi-Gb/s rates by exploiting low-level hardware and software techniques to meet the fastest network rates.\",\n \"Title: Multi-Gbps HTTP traffic analysis in commodity hardware based on local knowledge of TCP streams.\\nYear: 2017\\n\\nAbstract: In this paper we propose and implement novel techniques for performance evaluation of web traffic (response time, response code, etc.), with no reassembly of the underlying TCP connection, which severely restricts the traffic analysis throughput. Furthermore, our proposed software for HTTP traffic analysis runs in standard hardware, which is very cost-effective. Besides, we present sub-TCP connection load balancing techniques that significantly increase throughput at the expense of losing very few HTTP transactions. Such techniques provide performance evaluation statistics which are indistinguishable from the single-threaded alternative with full TCP connection reassembly.\",\n \"Title: Context-aware security framework based on Traffic Anomaly Detection Indicator.\\nYear: 2017\\n\\nAbstract: Context-aware security utilizes external data, such as time of the day or user information, to improve its capability of detecting a security breach. In this paper we present a Context-aware security framework based on a Traffic Anomaly Detection Indicator (TADI) which indicates when a threat can occur. The main novelty of our approach is that we use as a context the time-based information derived from profile analysis of a typical day to determine more accurately the presence of an anomaly based on the time of day it occurs. This 24-h typical daily analysis helps us to consider the time interval (night-time, working hours, etc.) in which a potential threat occurs, in contrast to traditional sudden peak changes. First, a preliminary analysis based on historical data shows how traffic typically behaves at each particular period of the day. We subsequently calibrate our procedure by checking the effectiveness of different algorithms so that we are aware of which ones gets better performance in each period of the day. Finally the TADI is calculated from the time-based contextual information. We also present the results based on actual traffic traces collected from a campus university that show the effectiveness of the proposed method.\",\n \"Title: Loginson: a transform and load system for very large-scale log analysis in large IT infrastructures\\nYear: 2017\\n\\nAbstract: AbstractNowadays, most systems and applications produce log records that are useful for security and monitoring purposes such as debugging programming errors, checking system status, and detecting configuration problems or even attacks. To this end, a log repository becomes necessary whereby logs can be accessed and visualized in a timely manner. This paper presents Loginson, a high-performance log centralization system for large-scale log collection and processing in large IT infrastructures. Besides log collection, Loginson provides high-level analytics through a visual interface for the purpose of troubleshooting critical incidents. We note that Loginson outperforms all of the other log centralization solutions by taking full advantage of the vertical scalability, and therefore decreasing Capital Expenditure (CAPEX) and Operating Expense (OPEX) costs for deployment scenarios with a huge volume of log data.\",\n \"Title: A Novel Blind Traffic Analysis Technique For Detection Of Whatsapp Voip Calls\\nYear: 2017\\n\\nAbstract: Nowadays social media plays a key role in interpersonal communication. Instant messaging applications, such as WhatsApp, are used by billions of users every day. Such application has recently been upgraded to support voice calls, whose traffic is transported over the top of network operators, as many other Voice over Internet Protocol (VoIP) services. In this work, we have characterized WhatsApp voice calls through blind traffic detection, which allows to differentiate WhatsApp calls from other applications, such as sharing video, photo, or messaging. Traditional techniques for detection of VoIP calls cannot be applied to the WhatsApp case because the traffic is obfuscated. Actually, our proposal only takes into account the WhatsApp traffic stream statistical features, and not the packet content. From the operators' point of view, the benefits of such a tool are manifold: from traffic prioritization to bespoke marketing campaigns to users that heavily produce WhatsApp voice calls.\",\n \"Title: Application of functional feature extraction to the compression of network time series\\nYear: 2017\\n\\nAbstract: Network management actions require the retention of data representing the temporal evolution of network state, mainly in the form of time series. Nonetheless, storing and exploiting those measurements is becoming a challenge as the production rate of such data is continuously increasing and data lasting for long time periods are used. To scale up the storage and improve both the analysis and visualization of network measurements, we apply Functional Principal Components Analysis (FPCA) to extract the most meaningful functional features for network time series, pruning those with low informational importance. We compare such algorithm with other state-of-the-art proposals, and show that it achieves lower error for the representation of atypical observations even with higher compression ratios.\",\n \"Title: On the impact of TCP segmentation: Experience in VoIP monitoring.\\nYear: 2017\\n\\nAbstract: Quality of Service (QoS) and Experience (QoE) monitoring is a must during the management of services deployed over the Internet. This is particularly critical for Voice over IP (VoIP), as its degradation is immediately perceived by end users. From our experience, we highlight the impact that TCP segmentation exerts on online VoIP monitoring systems. On the one hand, it makes difficult to interpret the segmented signaling messages for application monitoring. On the other hand, complete messages do not provide information about packet level behavior, which is necessary for internetworking layer monitoring. Paradoxically, the Network Management community has not paid much attention to this fact, although it compromises several VoIP management tasks. To fill in this gap, we provide an empirical evaluation of its impact for the most popular VoIP signaling protocols using traces from enterprise networks, and present the architecture and heuristic that we are currently developing to partially solve the effect of the segmentation. Our proposal avoids the overhead of reconstructing the entire data stream and, at the same time, it enables the analysis of the packets that are actually sent. To do so, it maps TCP flags with segmented application messages, and exploits data structures that reduce latency. In this way, our solution paves the way for online monitoring tools that take into account both internetworking and application layers performance.\",\n \"Title: Valley times in the Spanish academic network\\nYear: 2017\\n\\nAbstract: The scheduling of bulk transfers such as database distribution, resources replication and security backups, and other non-time-critical tasks has a direct effect on both the performance and cost of a network. We propose to face this problem by studying the valley times - i.e., the minimum use during off-peak periods of a network - as suitable moments to carry out such tasks. To do so, we characterize them considering the valley-hour, which we define as the opposite to the well-known variable busy-hour. Our analysis, based on 6-year-long measurements from 12 points of presence in the Spanish Research and Education Network (RedIRIS), has guided us to model the valley-hour as a Gaussian process. After that, we compare its behavior in different points and detect the main factors that explain its variance, finding significant heterogeneity. With the resulting conclusions, we have proposed a system to predict valley-hours in RedIRIS with errors below an hour for most of the cases.\",\n \"Title: Partial-Energy-Shaping Control For Orbital Stabilization Of High Frequency Oscillations Of The Furuta Pendulum\\nYear: 2007\\n\\nAbstract: We consider the problem of creating oscillations of the Furuta pendulum around the open-loop unstable equilibrium. Following a recently proposed technique, we start with shaping the energy of the unactuated link. An dissipativity-based controller is designed to create oscillations, neglecting possibility of unbounded motion of the directly actuated link. After that, an auxiliary linear feedback action is added to the control law, stabilizing a desired level of the reshaped energy. Parameters of the controller are tuned to approximately keep the originally created oscillations but ensuring bounded motion of both links. The analysis is valid only for oscillations of sufficiently high frequency and is based on higher order averaging technique. Performance of the designed controller is verified using numerical simulations and experiments.\",\n \"Title: Loginson: a transform and load system for very large-scale log analysis in large IT infrastructures.\\nYear: 2017\\n\\nAbstract: Nowadays, most systems and applications produce log records that are useful for security and monitoring purposes such as debugging programming errors, checking system status, and detecting configuration problems or even attacks. To this end, a log repository becomes necessary whereby logs can be accessed and visualized in a timely manner. This paper presents , a high-performance log centralization system for large-scale log collection and processing in large IT infrastructures. Besides log collection, provides high-level analytics through a visual interface for the purpose of troubleshooting critical incidents. We note that outperforms all of the other log centralization solutions by taking full advantage of the vertical scalability, and therefore decreasing Capital Expenditure (CAPEX) and Operating Expense (OPEX) costs for deployment scenarios with a huge volume of log data.\",\n \"Title: Diluting the Scalability Boundaries: Exploring the Use of Disaggregated Architectures for High-Level Network Data Analysis\\nYear: 2017\\n\\nAbstract: Traditional data centers are designed with a rigid architecture of fit-for-purpose servers that provision resources beyond the average workload in order to deal with occasional peaks of data. Heterogeneous data centers are pushing towards more cost-efficient architectures with better resource provisioning. In this paper we study the feasibility of using disaggregated architectures for intensive data applications, in contrast to the monolithic approach of server-oriented architectures. Particularly, we have tested a proactive network analysis system in which the workload demands are highly variable. In the context of the dReDBox disaggregated architecture, the results show that the overhead caused by using remote memory resources is significant, between 66% and 80%, but we have also observed that the memory usage is one order of magnitude higher for the stress case with respect to average workloads. Therefore, dimensioning memory for the worst case in conventional systems will result in a notable waste of resources. Finally, we found that, for the selected use case, parallelism is limited by memory. Therefore, using a disaggregated architecture will allow for increased parallelism, which, at the same time, will mitigate the overhead caused by remote memory.\",\n \"Title: Facing Network Management Challenges with Functional Data Analysis: Techniques & Opportunities.\\nYear: 2017\\n\\nAbstract: Current fixed and mobile networks’ behavior is rapidly changing, which calls for flexible monitoring approaches to avoid loosing track with such a fast evolutionary pace. Due to the many challenges that this scenario is posing to network managers, we propose the exploration of Functional Data Analysis (FDA) techniques as a mean to easily deal with network management and analysis issues. Specifically, we describe and evaluate several FDA methods with applications to network measurement preprocessing and clustering, bandwidth allocation, and anomaly and outlier detection. Our work focuses on how these FDA-based tools serve to improve the outcomes of traffic data mining and analysis, providing easy-to-understand and comprehensive outputs for network managers. We present the results that we have obtained from real case studies in the Spanish Academic network using throughput time series, comparing them with other alternatives of the state of the art. With this com- parative, we have qualitatively and quantitatively evaluated the advantages of FDA-methods in the networking area.\",\n \"Title: FlexiTop: a flexible and scalable network monitoring system for Over-The-Top services.\\nYear: 2017\\n\\nAbstract: Nowadays, the demand of Over-The-Top (OTT) services such as multimedia streaming, web services or social networking is rapidly increasing. Consequently, there is a wide interest in studying the quality of these services so that Internet Service Providers (ISP) can deliver the best experience to their clients. For this purpose, we present FlexiTop, a flexible and scalable system to actively monitor these OTT services, which allows an operator to obtain metrics with a limited resource usage. Due to the continuous evolution of OTT services, this system was designed with different approaches that can be extrapolated to future situations. By looking at the results, the proposal meets all the expectations and requirements and therefore it proves its success. The proposed design was implemented and validated with different alternatives whenever it was possible, both in wired and wireless networks. Moreover, long-time testing was performed to both ensure its stability and analyze the obtained data.\",\n \"Title: On The Use Of Affordable Cots Hardware For Network Measurements: Limits And Good Practices\\nYear: 2018\\n\\nAbstract: Wireless access technologies are widespread in domestic scenarios, and end users extensively use mobile phones or tablets to browse the Web. Therefore, methods and platforms for the measurement of network key performance indicators must be adapted to the peculiarities of this environment. In this light, the experiments should capture the true conditions of such connections, particularly in terms of the hardware and multi-device interactions that are present in real networks. On the basis of this, this paper presents an evaluation of the capabilities of several affordable commercial off-the-shelf (COTS) devices as network measuring probes, for example, computers-on-module or domestic routers with software measurement tools. Our main goal is to detect the limits of such devices and define a guide of good practices to optimize them. Hence, our work paves the way for the development of fair measurement systems in domestic networks with low expenditures. The obtained experimental results show that these types of devices are suitable as network measuring probes, if they are adequately configured and minimal accuracy losses are assumable.\",\n \"Title: Estimation of the parameters of token-buckets in multi-hop environments.\\nYear: 2018\\n\\nAbstract: Bandwidth verification in shaping scenarios receives much attention of both operators and clients because of its impact on Quality of Service (QoS). As a result, measuring shapers’ parameters, namely the Committed Information Rate (CIR), Peak Information Rate (PIR) and Maximum Burst Size (MBS), is a relevant issue when it comes to assess QoS. In this paper, we present a novel algorithm, TBCheck, which serves to accurately measure such parameters with minimal intrusiveness. These measurements are the cornerstone for the validation of Service Level Agreements (SLA) with multiple shaping elements along an end-to-end path. As a further outcome of this measurement method, we define a formal taxonomy of multi-hop shaping scenarios. A thorough performance evaluation covering the latter taxonomy shows the advantages of TBCheck compared to other tools in the state of the art, yielding more accurate results even in the presence of cross-traffic. Additionally, our findings show that MBS estimation is unfeasible when the link load is high, regardless the measurement technique, because the token-bucket will always be empty. Consequently, we propose an estimation policy which maximizes the accuracy by measuring CIR during busy hours and PIR and MBS during off-peak hours.\",\n \"Title: DNS weighted footprints for web browsing analytics.\\nYear: 2018\\n\\nAbstract: The monetization of the large amount of data that ISPs have of their users is still in early stages. Specifically, the knowledge of the websites that specific users or aggregates of users visit opens new opportunities of business, after the convenient sanitization. However, the construction of accurate DNS-based web-user profiles on large networks is a challenge not only because the requirements that capturing traffic entails, but also given the use of DNS caches, the proliferation of botnets and the complexity of current websites (i.e., when a user visit a website a set of self-triggered DNS queries for banners, from both same company and third parties services, as well for some preloaded and prefetching contents are in place). In this way, we propose to count the intentional visits users make to websites by means of DNS weighted footprints. Such novel approach consists of considering that a website was actively visited if an empirical-estimated fraction of the DNS queries of both the own website and the set of self-triggered websites are found. This approach has been coded in a final system named DNSprints. After its parameterization (i.e., balancing the importance of a website in a footprint with respect to the total set of footprints), we have measured that our proposal is able to identify visits and their durations with false and true positives rates between 2 and 9% and over 90%, respectively, at throughputs between 800,000 and 1.4 million DNS packets per second in diverse scenarios, thus proving both its refinement and applicability.\",\n \"Title: High-speed optical networks latency measurements in the microsecond timescale with software-based traffic injection.\\nYear: 2018\\n\\nAbstract: In many optical network scenarios, such as Storage Array Network (SAN) replication, keeping latency under control is cornerstone to provide a proper Quality of Service (QoS). Hence, measuring latencies in such optical networks becomes fundamental. However, for low distances, microseconds resolution is required, which, in turn, demands ad-hoc hardware implementation for the measurement device. Alternatively, a more cost-effective solution is that of software-based methods, but up to date they were not precise enough at 10 Gbit/s or above. In this paper, we analyze current high-performance packet engines, such as DPDK, and pinpoint the issues involved when it comes to measure latencies in high-speed optical networks. Based on these findings, we propose the use of a software-based solution to measure latency. Furthermore, we also propose an extension that serves to measure bandwidth as well, with the novel concept of convoy of packet trains.\",\n \"Title: On the analysis of burst-assembly delay in OBS networks and applications in delay-based service differentiation\\nYear: 2007\\n\\nAbstract: Optical Burst Switching (OBS), packets travel through the network core as part of longer-size optical bursts, which do not suffer electronic conversion until they reach an eggress point. Typically, such optical bursts comprise tens or hundreds of packets, which are assembled/deassembled at border nodes. During the burst-formation process, each arriving packet must wait until the final burst is complete, which clearly adds an extra delay on each packet in the burst, especially on those arriving earlier. However, such burst-assembly delay may be excessive for the appropriate performance of certain applications, mainly real-time interactive ones. This work's findings are twofold: first, it characterises the burst-assembly delay distribution of each packet in a burst arisen by the main assembly algorithms found in the literature; and, second, it introduces a new burst-assembly strategy that takes into account the particular delay constrains of packets in the formation of optical bursts, along with a detailed study of its properties.\",\n \"Title: On Burst Length Distribution and Preemption Probabilities in OBS Networks with Burst Segmentation\\nYear: 2006\\n\\nAbstract: Recently, preemption techniques have attracted considerable attention as a means to provide differentiated quality of service in optical burst switching (OBS) networks. This paper is focused on the analysis of preemption probabilities for bursts within the same priority class. As proposed by Vokkarane and Jue ((2003)* IEEE J Select Areas Commun 21(7): 1198-1209) an incoming burst will preempt the burst in service, within the same priority class, if the residual length of the burst in service is smaller than the incoming burst length. For a general case with wavelength conversion, the preemption probability of contending bursts with a generic service distribution, not necessarily exponential, is analyzed. First, we show that the size distribution for the preempting bursts is shifted to larger values, in comparison to the original burst size distribution. Second, we obtain an upper and lower bound for the preemption probability. Finally, the asymptotic behavior of the OBS switch is analyzed showing that preemption will always occur for a very large number of wavelengths.\",\n \"Title: Online detection of pathological TCP flows with retransmissions in high-speed networks.\\nYear: 2018\\n\\nAbstract: Online Quality of Service (QoS) assessment in high speed networks is one of the key concerns for service providers, namely to detect QoS degradation on-the-fly as soon as possible and avoid customers’ complaints. In this regard, a Key Performance Indicator (KPI) is the number of TCP retransmissions per flow, which is related to packet losses or increased network and/or client/server latency. However, to accurately detect TCP retransmissions the whole sequence number list should be tracked which is a challenging task in multi-Gb/s networks.\",\n \"Title: Making It Useful Even When It Seems to Be Useless [Opinion].\\nYear: 2018\\n\\nAbstract: Discusses how technology has played an essential role in the process of hominization. For humans, using technology to create an artificial world is as natural as it is for predators to hunt and kill their prey. In this respect, technology is inherent to human beings: there would be no humankind without technology, nor would there be technology without sociability. This leads to the core of technol...\",\n \"Title: On the design and performance evaluation of automatic traffic report generation systems with huge data volumes\\nYear: 2018\\n\\nAbstract: AbstractSummaryIn this paper, we analyze the performance issues involved in the generation of automated traffic reports for large IT infrastructures. Such reports allow the IT manager to proactively detect possible abnormal situations and roll out the corresponding corrective actions. With the ever‐increasing bandwidth of current networks, the design of automated traffic report generation systems is very challenging. In a first step, the huge volumes of collected traffic are transformed into enriched flow records obtained from diverse collectors and dissectors. Then, such flow records, along with time series obtained from the raw traffic, are further processed to produce a usable report. As will be shown, the data volume in flow records turns out to be very large as well and requires careful selection of the key performance indicators (KPIs) to be included in the report. In this regard, we discuss the use of high‐level languages versus low‐level approaches, in terms of speed and versatility. Furthermore, our design approach is targeted for rapid development in commodity hardware, which is essential to cost‐effectively tackle demanding traffic analysis scenarios. Actually, the paper shows feasibility of delivering a large number of KPIs, as will be detailed later, for several TBytes of traffic per day using a commodity hardware architecture and high‐level languages.We analyze the performance issues involved in the generation of automated traffic reports for large IT infrastructures. Such reports allow the IT manager to proactively detect possible abnormal situations and roll out the corresponding corrective actions. With the ever‐increasing bandwidth of current networks, the design of automated traffic report generation systems is very challenging. Our approach is targeted for rapid development in commodity hardware, which is essential to cost‐effectively tackle demanding traffic analysis scenarios. View Figure\",\n \"Title: KISS Methodologies for Network Management and Anomaly Detection\\nYear: 2019\\n\\nAbstract: Current networks are increasingly growing in size, complexity and the amount of monitoring data that they produce, which requires complex data analysis pipelines to handle data collection, centralization and analysis tasks. Literature approaches, include the use of custom agents to harvest information and large data centralization systems based on clusters to achieve horizontal scalability, which are expensive and difficult to deploy in real scenarios. In this paper we propose and evaluate a series of methodologies, deployed in real industrial production environments, for network management, from the architecture design to the visualization system as well as for the anomaly detection methodologies, that intend to squeeze the vertical resources and overcome the difficulties of data collection and centralization.\",\n \"Title: On the design and performance evaluation of automatic traffic report generation systems with huge data volumes.\\nYear: 2018\\n\\nAbstract: In this paper we analyze the performance issues involved in the generation of auto- mated traffic reports for large IT infrastructures. Such reports allows the IT manager to proactively detect possible abnormal situations and roll out the corresponding cor- rective actions. With the ever-increasing bandwidth of current networks, the design of automated traffic report generation systems is very challenging. In a first step, the huge volumes of collected traffic are transformed into enriched flow records obtained from diverse collectors and dissectors. Then, such flow records, along with time series obtained from the raw traffic, are further processed to produce a usable report. As will be shown, the data volume in flow records is very large as well and requires careful selection of the Key Performance Indicators (KPIs) to be included in the report. In this regard, we discuss the use of high-level languages versus low- level approaches, in terms of speed and versatility. Furthermore, our design approach is targeted for rapid development in commodity hardware, which is essential to cost-effectively tackle demanding traffic analysis scenarios.\",\n \"Title: Wormhole: a novel big data platform for 100 Gbit/s network monitoring and beyond\\nYear: 2019\\n\\nAbstract: Internet measurement and analysis is increasingly challenging as the Internet evolves, primarily due to changing-trends, speed increments or new protocols and ciphers. As such, ad-hoc monitoring equipment comes in handy, albeit cost-effectiveness impedes deployment at a very large scale. As an alternative, big data-based distributed architectures are being proposed for network monitoring and analysis. However, in light of the high throughput currently offered by 100 Gbit/s links, it turns out that state-of-the-art big data solutions fall short of capacity, unless a huge amount of computers are used. In order to effectively tackle that issue, we have created Wormhole: a streaming engine that circumvents existing limitations by distributing the input messages/packets coherently among different off-the-shelf analysis equipment, thus reducing costs and equipment. Should the incoming data rate be larger than the system throughput, a distributed file system can be used for temporary data storage, for subsequent filtering and in-depth analysis. The proposed solution provides on-line real-time monitoring metrics with the ability to gain further insights when required. The prototyped architecture is able to deal with 100 Gbit/s networks and can be easily scaled up to higher rates by just adding more computing nodes and/or by trimming encrypted packet payloads.\",\n \"Title: Flow-concurrence and bandwidth ratio on the Internet\\nYear: 2019\\n\\nAbstract: The relevance of flow-based monitoring in tasks such as the detection of anomalies and denial of use attacks, traffic reporting, performance evaluation, software routing among others motivates the study of the Internet traffic in terms of flows. However, by the time a network manager or practitioner start any of these tasks, they face the challenge of planning probes’ capacities, which depends on the number of concurrent flows. Unfortunately, while the bandwidth of a network or link, both in operation and in future deployments, can be known, or at least estimated in advance, nothing is known about the load in terms of concurrent flows. We aimed at filling this gap by studying the concurrence of flows with respect to the bandwidth normalized by factors such as protocol shares, timeouts, applications, time and years among others. As a result, we provide the research community with several models, based on lognormal distributions, and parameter estimates in such a way that any player in the Internet arena can estimate the number of concurrent flows in their own infrastructure. Moreover, such results emerge from a diverse set of network traces so making the extrapolation of conclusions viable.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":85,"string":"85"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":272,"string":"272"}}},{"rowIdx":273,"cells":{"question_id":{"kind":"string","value":"Xiaohui Yu"},"question":{"kind":"string","value":"Generate an abstract for the title \"NLPMM: A Next Location Predictor with Markov Modeling.\" using the following items: 1. Predicting locations\n2. Next Location Predictor\n3. Markov Modeling\n4. Individual & collective movement patterns\n5. Real dataset"},"answer":{"kind":"string","value":"In this paper, we solve the problem of predicting the next locations of the moving objects with a historical dataset of trajectories. We present a Next Location Predictor with Markov Modeling (NLPMM) which has the following advantages: (1) it considers both individual and collective movement patterns in making prediction, (2) it is effective even when the trajectory data is sparse, (3) it considers the time factor and builds models that are suited to different time periods. We have conducted extensive experiments in a real dataset, and the results demonstrate the superiority of NLPMM over existing methods."},"correct_answer":{"kind":"string","value":"In this paper, we solve the problem of predicting the next locations of the moving objects with a historical dataset of trajectories. We present a Next Location Predictor with Markov Modeling (NLPMM) which has the following advantages: (1) it considers both individual and collective movement patterns in making prediction, (2) it is effective even when the trajectory data is sparse, (3) it considers the time factor and builds models that are suited to different time periods. We have conducted extensive experiments in a real dataset, and the results demonstrate the superiority of NLPMM over existing methods."},"documents":{"kind":"list like","value":["Title: HadoopRsync\nYear: 2011\n\nAbstract: Cloud storage has become increasingly popular due to its convenience, cost-effectiveness and scalability. It provides the basis for a slate of file hosting services, which offer users the ability to synchronize their files between the servers and their devices. Naive file synchronization, however, requires the whole file to be transmitted to all other locations (servers, devices) whenever the file is updated in one location. This leads to massive waste of bandwidth and significant delays in propagating the update. We propose a method called HadoopRsync, which is capable of performing incremental update of files instead of transmitting them in entirety. This method is based on the rsync utility originally proposed for file synchronization between computers, but the scenario under consideration is significantly different from that for rsync in that in the cloud storage context, files are distributedly stored at multiple nodes in the cloud. We therefore propose a pair of algorithms called HadoopRsync Upload and HadoopRsync Download, which are responsible for the synchronization from the user's devices to the cloud and the synchronization in the opposite direction respectively. These algorithms only transmit the differences between the new version of the file and the old version, rather than the whole file. Our solution is based on Hadoop, the open-source framework for distributed processing of very large data across clusters of computers. The algorithms utilize the MapReduce facility provided by Hadoop to fully taking advantage of its massive-parallelization capability. In addition, we propose some optimization measures to reduce the I/Os required for file update. Extensive experiments are conducted to evaluate the proposed solution, which show that HadoopRsync significantly outperforms the baseline methods.","Title: Keyword query cleaning\nYear: 2008\n\nAbstract: Unlike traditional database queries, keyword queries do not adhere to predefined syntax and are often dirty with irrelevant words from natural languages. This makes accurate and efficient keyword query processing over databases a very challenging task. In this paper, we introduce the problem of query cleaning for keyword search queries in a database context and propose a set of effective and efficient solutions. Query cleaning involves semantic linkage and spelling corrections of database relevant query words, followed by segmentation of nearby query words such that each segment corresponds to a high quality data term. We define a quality metric of a keyword query, and propose a number of algorithms for cleaning keyword queries optimally. It is demonstrated that the basic optimal query cleaning problem can be solved using a dynamic programming algorithm. We further extend the basic algorithm to address incremental query cleaning and top-k optimal query cleaning. The incremental query cleaning is efficient and memory-bounded, hence is ideal for scenarios in which the keywords are streamed. The top-k query cleaning algorithm is guaranteed to return the best k cleaned keyword queries in ranked order. Extensive experiments are conducted on three real-life data sets, and the results confirm the effectiveness and efficiency of the proposed solutions.","Title: Alternative Query Optimization for Workload Management.\nYear: 2012\n\nAbstract: Systems with heavy workloads run many queries concurrently. Modern database workloads-as those incurred by business intelligence applications-involve ad-hoc, highly complex, expensive queries. While query plans are optimized individually, the workload overall is not. Plans running together incur resource contention, resulting in sub-optimal performance. To address this, we introduce the idea of alternative-objective query optimization. Multiple query plans for the same query are generated, each optimized for an alternative resource usage. At runtime, the workload manager then can choose the plan for the query that works best for runtime conditions. This balances the system load, reducing contention, to increase overall workload throughput. © 2012 Springer-Verlag.","Title: DDSN: Duplicate detection to reduce both storage and bandwidth consumption\nYear: 2013\n\nAbstract: As highly centralized storage facilities are gaining popularity, duplicate detection becomes a critical problem. Traditional methods focus on reducing the storage space consumption; however, for network storage system with remote clients, the network overhead cannot be ignored, especially when the system is accessed over WAN. We propose a new duplicate detection method and implement a network file system prototype called DDSN based on this new method. It can reach the same performance in terms of storage space consumption as the state-of-the-art sliding blocking method. Meanwhile, our method overcomes its drawback that the whole file needs to be transmitted over the network, and therefore saves massive bandwidth for duplicate data. Experiments confirm the effectiveness of the proposed method.","Title: Fast approximate computation of statistics on views\nYear: 2006\n\nAbstract: Accurate estimation of the sizes of intermediate query results (cardinality estimation) is of critical importance to plan costing in query optimization. The common practice in current commercial database systems such as IBM DB2 Universal Database (DB2 UDB) is to derive the cardinality estimates from base-table statistics. However, this approach often suffers from simplifying yet unrealistic assumptions that have to be made about the underlying data (for example, different attributes are independently distributed).Ways for exploiting statistics on query expressions (or, statistics on views, or SITs) have been proposed to improve the accuracy of cardinality estimation. We propose a novel method for efficient computation of SITs for joins. In particular, we are concerned with statistics on join queries involving large fact tables and relatively small dimension tables. Rather than materializing the views, we make use of the frequency statistics that are available on the fact tables to obtain an approximate estimate of the statistics on various attributes in the join results. The dimension tables are generally much smaller than the fact table, and therefore we can afford to closely examine the dimension table, while at the same time avoid accessing the fact table. By closely examining the dimension table, we are able to capture the correlations between the attributes in the dimension table as well as the skew and domain range of the fact table join column values. This leads to reasonably accurate statistics on the join result. We prototyped this idea as a module on top of DB2 UDB, and our experience shows that employment of this technique results in a very significant speed-up in the computation of SITs, at the expense of only slight degradation in accuracy compared with the full-materialization method.","Title: Indexing high-dimensional data for main-memory similarity search\nYear: 2010\n\nAbstract: As RAM gets cheaper and larger, in-memory processing of data becomes increasingly affordable. In this paper, we propose a novel index structure, the CSR^+-tree, to support efficient high-dimensional similarity search in main memory. We introduce quantized bounding spheres (QBSs) that approximate bounding spheres (BSs) or data points. We analyze the respective pros and cons of both QBSs and the previously proposed quantized bounding rectangles (QBRs), and take the best of both worlds by carefully incorporating both of them into the CSR^+-tree. We further propose a novel distance computation scheme that eliminates the need for decompressing QBSs or QBRs, which results in significant cost savings. We present an extensive experimental evaluation and analysis of the CSR^+-tree, and compare its performance against that of other representative indexes in the literature. Our results show that the CSR^+-tree consistently outperforms other index structures.","Title: Mining Online Reviews for Predicting Sales Performance: A Case Study in the Movie Domain\nYear: 2012\n\nAbstract: Posting reviews online has become an increasingly popular way for people to express opinions and sentiments toward the products bought or services received. Analyzing the large volume of online reviews available would produce useful actionable knowledge that could be of economic values to vendors and other interested parties. In this paper, we conduct a case study in the movie domain, and tackle the problem of mining reviews for predicting product sales performance. Our analysis shows that both the sentiments expressed in the reviews and the quality of the reviews have a significant impact on the future sales performance of products in question. For the sentiment factor, we propose Sentiment PLSA (S-PLSA), in which a review is considered as a document generated by a number of hidden sentiment factors, in order to capture the complex nature of sentiments. Training an S-PLSA model enables us to obtain a succinct summary of the sentiment information embedded in the reviews. Based on S-PLSFA, we propose ARSA, an Autoregressive Sentiment-Aware model for sales prediction. We then seek to further improve the accuracy of prediction by considering the quality factor, with a focus on predicting the quality of a review in the absence of user-supplied indicators, and present ARSQA, an Autoregressive Sentiment and Quality Aware model, to utilize sentiments and quality for predicting product sales performance. Extensive experiments conducted on a large movie data set confirm the effectiveness of the proposed approach.","Title: An extension of cooperative fuzzy games\nYear: 2010\n\nAbstract: In this paper, a generalized form of fuzzy game is proposed that can be seen as an extension of the cooperative fuzzy game. Players in the proposed fuzzy game do not need to know precise information about the payoff value or to form a crisp coalition. Based on the Hukuhara difference, a game with a fuzzy characteristic function is studied, and the explicit form of a Shapley function is shown. Furthermore, we introduce and investigate a new class of fuzzy game with fuzzy coalitions and a fuzzy characteristic function. Based on the Hukuhara difference and the Choquet integral, we give the explicit form of the Shapley value for the new class of fuzzy game. It has been seen that most of the properties of a crisp game hold well in the proposed fuzzy game. A practical application of the proposed model in joint production problem is also provided.","Title: Sentence-Level Sentiment Analysis in the Presence of Modalities\nYear: 2014\n\nAbstract: This paper studies sentiment analysis of sentences with modality. The aim is to determine whether opinions expressed in sentences with modality are positive, negative or neutral. Modality is commonly used in text. In a typical corpus, there are around 18% of sentences with modality. Due to modality's special characteristics, the sentiment it bears may be hard to determine. For example, in the sentence, this cellphone would be perfect if it has a bigger screen, the speaker is negative about this phone although there is a typically positive opinion word \\\"perfect\\\" in this sentence. This paper first presents a linguistic analysis of modality, and then identifies some features to train a support vector machine classifier to determine the sentiment orientation in such sentences. Experimental results on sentences with modality extracted from the reviews of four different products are given to illustrate the effectiveness of the proposed method.","Title: An Adaptive Model for Probabilistic Sentiment Analysis\nYear: 2010\n\nAbstract: Online reviews, which are getting increasingly prevalent with the rapid growth of Web 2.0, have been shown to be second only to \"word-of-mouth\" in terms of influencing purchase decisions. It is therefore imperative to analyze them and distill useful knowledge that could be of economic values to vendors and other interested parties. Previous studies have confirmed that the sentiments expressed in the online reviews are strongly correlated with the sales performance of products. In particular, a model called ARSA has been proposed for predicting sales performance using a model called S-PLSA. In this paper, we build upon that work, and present an adaptive sentiment analysis model called S-PLSA+, which not only can capture the hidden sentiment factors in the reviews, but has the capability to be incrementally updated as more data become available. We show how the proposed S-PLSA+ model can be applied to sales performance prediction using the ARSA model. A case study is conducted in the movie domain, and results from preliminary experiments confirm the effectiveness of the proposed model.","Title: Reasoning About Approximate Match Query Results\nYear: 2006\n\nAbstract: Join techniques deploying approximate match predicates are fundamental data cleaning operations. A variety of predicates have been utilized to quantify approximate match in such operations and some have been embedded in a declarative data cleaning framework. These techniques return pairs of tuples from both relations, tagged with a score, signifying the degree of similarity between the tuples in the pair according to the specific approximate match predicate. In this paper, we consider the problem of estimating various parameters on the output of declarative approximate join algorithms for planning purposes. Such algorithms are highly time consuming, so precise knowledge of the result size as well as its score distribution is a pressing concern. This knowledge aids decisions as to which operations are more promising for identifying highly similar tuples, which is a key operation for data cleaning. We propose solution strategies that fully comply with a declarative framework and analytically reason about the quality of the estimates we obtain as well as the performance of our strategies. We present the results of a detailed performance evaluation of all strategies proposed. Our experimental results validate our analytical expectations and shed additional light on the quality and performance of our estimation framework. Our study offers a set of simple, fully declarative techniques for this problem, which can be readily deployed in data cleaning systems.","Title: S-PLASA+: adaptive sentiment analysis with application to sales performance prediction\nYear: 2010\n\nAbstract: Analyzing the large volume of online reviews would produce useful knowledge that could be of economic values to vendors and other interested parties. In particular, the sentiments expressed in the online reviews have been shown to be strongly correlated with the sales performance of products. In this paper, we present an adaptive sentiment analysis model called S-PLSA+, which aims to capture the hidden sentiment factors in the reviews with the capability to be incrementally updated as more data become available. We show how S-PLSA+ can be applied to sales performance prediction using an ARSA model developed in previous literature. A case study is conducted in the movie domain, and results from preliminary experiments confirm the effectiveness of the proposed model.","Title: Towards estimating the number of distinct value combinations for a set of attributes\nYear: 2005\n\nAbstract: Accurately and efficiently estimating the number of distinct values for some attribute(s) or sets of attributes in a data set is of critical importance to many database operations, such as query optimization and approximation query answering. Previous work has focused on the estimation of the number of distinct values for a single attribute and most existing work adopts a data sampling approach. This paper addresses the equally important issue of estimating the number of distinct value combinations for multiple attributes which we call COLSCARD (for COLumn Set CARDinality). It also takes a different approach that uses existing statistical information (e.g., histograms) available on the individual attributes to assist estimation. We start with cases where exact frequency information on individual attributes is available, and present a pair of lower and upper bounds on COLSCARD that are consistent with the available information, as well as an estimator of COLSCARD based on probability. We then proceed to study the case where only partial information (in the form of histograms) is available on individual attributes, and show how the proposed estimator can be adapted to this case. We consider two types of widely used histograms and show how they can be constructed in order to obtain optimal approximation. An experimental evaluation of the proposed estimation method on synthetic as well as two real data sets is provided.","Title: HASE: a hybrid approach to selectivity estimation for conjunctive predicates\nYear: 2006\n\nAbstract: Current methods for selectivity estimation fall into two broad categories, synopsis-based and sampling-based. Synopsis-based methods, such as histograms, incur minimal overhead at query optimization time and thus are widely used in commercial database systems. Sampling-based methods are more suited for ad-hoc queries, but often involve high I/O cost because of random access to the underlying data. Though both methods serve the same purpose of selectivity estimation, their interaction in the case of selectivity estimation for conjuncts of predicates on multiple attributes is largely unexplored. Our work aims at taking the best of both worlds, by making consistent use of synopses and sample information when they are both present. To achieve this goal, we propose HASE, a novel estimation scheme based on a powerful mechanism called generalized raking. We formalize selectivity estimation in the presence of single attribute synopses and sample information as a constrained optimization problem. By solving this problem, we obtain a new set of weights associated with the sampled tuples, which has the nice property of reproducing the known selectivities when applied to individual predicates. We discuss different variants of the optimization problem and provide algorithms for solving it. We also provide asymptotic error bounds on the estimate. Extensive experiments are performed on both synthetic and real data, and the results show that HASE significantly outperforms both synopsis-based and sampling-based methods.","Title: CSR+-tree: Cache-conscious Indexing for High-dimensional Similarity Search\nYear: 2007\n\nAbstract: In this paper, we propose a novel index structure, the CSR+-tree, to support efficient high-dimensional similarity search in main memory. We introduce quantized bounding spheres (QBSs) that approximate bounding spheres (BSs) or data points. We analyze the respective pros and cons of both QBSs and the previously proposed quantized bounding rectangles (QBRs), and take the best of both worlds by carefully incorporating both of them into the CSR+-tree. We further propose a novel distance computation scheme that eliminates the need for decompressing QBSs or QBRs, which results in significant cost savings. We present an extensive experimental evaluation and analysis of the CSR+-tree, and compare its performance against that of other representative indexes in the literature. Our results show that the CSR+-tree consistently outperforms other index structures.","Title: Reasoning about similarity queries in text retrieval tasks\nYear: 2008\n\nAbstract: In many text retrieval tasks, it is highly desirable to obtain a \"similarity profile\" of the document collection for a given query. We propose sampling-based techniques to address this need, using calibration techniques to improve the accuracy. Experimental results confirm the effectiveness of the proposed approaches.","Title: Riding the tide of sentiment change: sentiment analysis with evolving online reviews\nYear: 2013\n\nAbstract: The last decade has seen a rapid growth in the volume of online reviews. A great deal of research has been done in the area of opinion mining, aiming at analyzing the sentiments expressed in those reviews towards products and services. Most of the such work focuses on mining opinions from a collection of reviews posted during a particular period, and does not consider the change in sentiments when the collection of reviews evolve over time. In this paper, we fill in this gap, and study the problem of developing adaptive sentiment analysis models for online reviews. Given the success of latent semantic modeling techniques, we propose two adaptive methods to capture the evolving sentiments. As a case study, we also investigate the possibility of using the extracted adaptive patterns for sales prediction. Our proposal is evaluated on an IMDB dataset consisting of reviews of selected movies and their box office revenues. Experimental results show that the adaptive methods can capture sentiment changes arising from newly available reviews, which helps greatly improve the prediction accuracy.","Title: Sharpe Ratio-Oriented Active Trading: A Learning Approach\nYear: 2002\n\nAbstract: Portfolio offers an effective way for managing investment risk through diversification. The key issue in portfolio management is how to determine the weight (portion) of each asset in the portfolio, so as to achieve high profit with low risk over a certain period of trading. We propose a learning-based trading strategy for portfolio management, which aims at maximizing the Sharpe Ratio by actively reallocating wealth among assets. The trading decision is formulated as a non-linear function of the latest realized asset returns, and the function can be approximated by a neural-network. Two methods based on supervised learning to train the network are proposed. Experiments show that the proposed trading strategy outperforms the static Sharpe Ratio trading method.","Title: Pollux: towards scalable distributed real-time search on microblogs\nYear: 2013\n\nAbstract: The last few years have witnessed a meteoric rise of microblogging platforms, such as Twitter and Tumblr. The sheer volume of the microblog data and its highly dynamic nature present unique technical challenges for the platforms that provide search services. In particular, the search service must provide real-time response to queries, and continuously update the results as new microblogs are posted. Conventional approaches either cannot keep up with the high update rate, or cannot scale well to handle the large volume of data. We propose Pollux, a system that provides distributed real-time indexing and search service on microblogs. It adopts the distributed stream processing paradigm advocated by the recently developed platforms that are designed for real-time processing of large volume of data, such as Apache S4 and Twitter Storm. Although those open-source platforms have found successful applications in production environments, they lack some critical features required for real-time search. In particular: (1) they only implement partial fault tolerance, and do not provide lossless recovery in the event of a node failure, and (2) they do not have a facility for storing global data, which is necessary in efficiently ranking search results. Addressing those problems, Pollux extends current platforms in two important ways. First, we propose a failover strategy that can ensure high system availability and no data/state loss in the event of a node failure. Second, Pollux adds a global storage facility that supports convenient, efficient, and reliable data storage for shared data. We describe how to apply Pollux to the task of real-time search. We implement Pollux based on Apache S4, and show through extensive experiments on a Twitter dataset that the proposed solutions are effective, and Pollux can achieve excellent scalability.","Title: Keyword query cleaning with query logs\nYear: 2011\n\nAbstract: Keyword queries over databases are often dirty with some irrelevant or incorrect words, which has a negative impact on the efficiency and accuracy of keyword query processing. In addition, the keywords in a given query often form natural segments. For example, the query \"Tom Hanks Green Mile\" can be considered as consisting of two segments, \"Tom Hanks\" and \"Green Mile\".The goal of keyword query cleaning is to identify the optimal segmentation of the query, with semantic linkage and spelling corrections also considered.Query cleaning not only helps obtaining queries of higher quality, but also improves the efficiency of query processing by reducing the search space. The seminal work along this direction by Pu and Yu does not consider the role of query logs in performing query cleaning. Query logs contain user-issued queries together with the segmentations chosen by the user, and thus convey important information that reflects user preferences. In this paper, we explore the use of query logs to improve the quality of keyword query cleaning. We propose two methods to adapt the scoring functions of segmentations to account for information gathered from the logs. The effectiveness of our approach are verified with extensive experiments conducted on real data sets.","Title: Hashed samples: selectivity estimators for set similarity selection queries\nYear: 2008\n\nAbstract: We study selectivity estimation techniques for set similarity queries. A wide variety of similarity measures for sets have been proposed in the past. In this work we concentrate on the class of weighted similarity measures (e.g., TF/IDF and BM25 cosine similarity and variants) and design selectivity estimators based on a priori constructed samples. First, we study the pitfalls associated with straightforward applications of random sampling, and argue that care needs to be taken in how the samples are constructed; uniform random sampling yields very low accuracy, while query sensitive realtime sampling is more expensive than exact solutions (both in CPU and I/O cost). We show how to build robust samples a priori, based on existing synopses for distinct value estimation. We prove the accuracy of our technique theoretically, and verify its performance experimentally. Our algorithm is orders of magnitude faster than exact solutions and has very small space overhead.","Title: FRISK: Keyword Query Cleaning and Processing in Action\nYear: 2009\n\nAbstract: Keyword search provides a simple yet effective way for the users to query and explore the underlying documents. In the recent years, there have been a great deal of research and development activities on extending keyword search capabilities to handle relational data, the dominant form in which business data are stored. Algorithms and prototype systems, such as Discover, DBXplorer, BANKS, and SPARK, have been developed to support retrieving relevant information from relational databases using keyword queries.","Title: ARSA: a sentiment-aware model for predicting sales performance using blogs\nYear: 2007\n\nAbstract: Due to its high popularity, Weblogs (or blogs in short) present a wealth of information that can be very helpful in assessing the general public's sentiments and opinions. In this paper, we study the problem of mining sentiment information from blogs and investigate ways to use such information for predicting product sales performance. Based on an analysis of the complex nature of sentiments, we propose Sentiment PLSA (S-PLSA), in which a blog entry is viewed as a document generated by a number of hidden sentiment factors. Training an S-PLSA model on the blog data enables us to obtain a succinct summary of the sentiment information embedded in the blogs. We then present ARSA, an autoregressive sentiment-aware model, to utilize the sentiment information captured by S-PLSA for predicting product sales performance. Extensive experiments were conducted on a movie data set. We compare ARSA with alternative models that do not take into account the sentiment information, as well as a model with a different feature selection method. Experiments confirm the effectiveness and superiority of the proposed approach.","Title: Collaborative Filtering with Aspect-Based Opinion Mining: A Tensor Factorization Approach\nYear: 2012\n\nAbstract: Collaborative filtering (CF) aims to produce user specific recommendations based on other users' ratings of items. Most existing CF methods rely only on users' overall ratings of items, ignoring the variety of opinions users may have towards different aspects of the items. Using the movie domain as a case study, we propose a framework that is able to capture users' opinions on different aspects from the textual reviews, and use that information to improve the effectiveness of CF. This framework has two components, an opinion mining component and a rating inference component. The former extracts and summarizes the opinions on multiple aspects from the reviews, generating ratings on the various aspects. The latter component, on the other hand, infers the overall ratings of items based on the aspect ratings, which forms the basis for item recommendation. Our core contribution is in the proposal of a tensor factorization approach for the rating inference. Operating on the tensor composed of the overall and aspect ratings, this approach is able to capture the intrinsic relationships between users, items, and aspects, and provide accurate predictions on unknown ratings. Experiments on a movie dataset show that our proposal significantly improves the prediction accuracy compared with two baseline methods.","Title: Query segmentation using conditional random fields\nYear: 2009\n\nAbstract: A growing mount of available text data are being stored in relational databases, giving rise to an increasing need for the RDBMSs to support effective text retrieval. In this paper, we address the problem of keyword query segmentation, i.e., how to group nearby keywords in a query into segments. This operation can greatly benefit both the quality and the efficiency of the subsequent search operations. Compared with previous work, the proposed approach is based on Conditional Random Fields (CRF), and provides a principled statistical model that can be learned from query logs and easily adapt to user preferences. Extensive experiments on two real datasets confirm the effectiveness the efficiency of the proposed approach.","Title: HelpMeter: A Nonlinear Model for Predicting the Helpfulness of Online Reviews\nYear: 2008\n\nAbstract: With the flourish of the Internet, online review mining has attracted a lot of attention from the research community. However, compared to various well-studied sentiment analysis and opinion summarization problems, less effort has been made to analyze the quality of online reviews. The objective of this paper is to fill in this gap by automatically evaluating the \"helpfulness\" of reviews and consequently developing novel models to identify the most helpful reviews for a particular product. In particular, based on a thorough analysis of various factors that may affect the review quality, we propose HelpMeter, a nonlinear regression model for helpfulness prediction. Some preliminary experiments were conducted on a movie review data set, and the performance results confirm the superiority of the proposed method.","Title: Efficient Top-k Keyword Search Over Multidimensional Databases\nYear: 2013\n\nAbstract: Keyword search over databases has recently received significant attention. Many solutions and prototypes have been developed. However, due to large memory consumption requirements and unpredictable running time, most of them cannot be applied directly to the situations where memory is limited and quick response is required, such as when performing keyword search over multidimensional databases in mobile devices as part of the OLAP functionalities. In this paper, the authors attack the keyword search problem from a new perspective, and propose a cascading top-k keyword search algorithm, which generates supernodes by a branch and bound method in each step of search instead of computing the Steiner trees as done in many existing approaches. This new algorithm consumes less memory and significantly reduces the response time. Experiments show that the method can achieve high search efficiency compared with the state-of-the-art approaches.","Title: Existence of an elliptic system involving Pucci operator\nYear: 2008\n\nAbstract: We study the existence of solutions for the nonlinear elliptic system {−Mλ,Λ+(D2u)=f1(x,u)+h1(u,v)in Ω,−Mλ,Λ+(D2v)=f2(x,v)+h2(u,v)in Ω,u>0,v>0in Ω,u=v=0on ∂Ω, where Ω is a bounded domain, f1 is superlinear and f2 is sublinear at zero and infinity, h1 and h2 are perturbation terms. We will show that the system has at least two semi-trivial solutions (u,0), (0,v) and a nontrivial solution (u∗,v∗).","Title: Cascading top-k keyword search over relational databases\nYear: 2011\n\nAbstract: Keyword search over relational databases has recently received significant attention. Many solutions and prototypes have been developed. However, due to large memory consumption requirements and unpredictable running time, most of them cannot be applied directly to situations where memory is limited and quick response is required, such as when performing keyword search over databases in mobile devices as part of the OLAP funtionalities. In this paper, we attack the keyword search problem from a new perspective, and propose a cascading top-k keyword search algorithm, which generates supernodes in each step of search instead of computing the Steiner trees as done in many existing approaches. This new algorithm consumes less memory and significantly reduces the response time. Experiments show that the method can achieve high search efficiency compared with the state-of-the-art approaches.","Title: Combining integrated sampling with SVM ensembles for learning from imbalanced datasets\nYear: 2011\n\nAbstract: Learning from imbalanced datasets is difficult. The insufficient information that is associated with the minority class impedes making a clear understanding of the inherent structure of the dataset. Most existing classification methods tend not to perform well on minority class examples when the dataset is extremely imbalanced, because they aim to optimize the overall accuracy without considering the relative distribution of each class. In this paper, we study the performance of SVMs, which have gained great success in many real applications, in the imbalanced data context. Through empirical analysis, we show that SVMs may suffer from biased decision boundaries, and that their prediction performance drops dramatically when the data is highly skewed. We propose to combine an integrated sampling technique, which incorporates both over-sampling and under-sampling, with an ensemble of SVMs to improve the prediction performance. Extensive experiments show that our method outperforms individual SVMs as well as several other state-of-the-art classifiers.","Title: Modeling and Predicting the Helpfulness of Online Reviews\nYear: 2008\n\nAbstract: Online reviews provide a valuable resource for potential customers to make purchase decisions. However, the sheer volume of available reviews as well as the large variations in the review quality present a big impediment to the effective use of the reviews, as the most helpful reviews may be buried in the large amount of low quality reviews. The goal of this paper is to develop models and algorithms for predicting the helpfulness of reviews, which provides the basis for discovering the most helpful reviews for given products. We first show that the helpfulness of a review depends on three important factors: the reviewerpsilas expertise, the writing style of the review, and the timeliness of the review. Based on the analysis of those factors, we present a nonlinear regression model for helpfulness prediction. Our empirical study on the IMDB movie reviews dataset demonstrates that the proposed approach is highly effective.","Title: CI-Rank: Ranking Keyword Search Results Based on Collective Importance\nYear: 2012\n\nAbstract: Keyword search over databases, popularized by keyword search in WWW, allows ordinary users to access database information without the knowledge of structured query languages and database schemas. Most of the previous studies in this area use IR-style ranking, which fail to consider the importance of the query answers. In this paper, we propose CI-RANK, a new approach for keyword search in databases, which considers the importance of individual nodes in a query answer and the cohesiveness of the result structure in a balanced way. CI-RANK is built upon a carefully designed model call Random Walk with Message Passing that helps capture the relationships between different nodes in the query answer. We develop a branch and bound algorithm to support the efficient generation of top-k query answers. Indexing methods are also introduced to further speed up the run-time processing of queries. Extensive experiments conducted on two real data sets with a real user query log confirm the effectiveness and efficiency of CI-RANK.","Title: Traffic Session Identification Based on Statistical Language Model\nYear: 2013\n\nAbstract: Session identification has attracted a lot of attention as it can play an important role in discovering useful patterns. A traffic session is a sequence of camera locations orderly passed by a vehicle to achieve a certain task. Based on the observations that both navigation regularity and temporal factor are crucial in determining the session boundaries, we propose an improved statistical language model which takes both factors into consideration in this paper. Extensive experiments are conducted on a real traffic dataset to testify the effectiveness of our proposal, and the result demonstrates its effectiveness compared to other alternative methods including the timeout method and the classic language model.","Title: A quality-aware model for sales prediction using reviews\nYear: 2010\n\nAbstract: Writing and publishing reviews online has become an increasingly popular way for people to express opinions and sentiments. Analyzing the large volume of online reviews available can produce useful knowledge that are of interest to vendors and other parties. Prior studies in the literature have shown that online reviews have a significant correlation with the sales of products, and therefore mining the reviews could help predict the sales performance of relevant products. However, those studies fail to consider one important factor that may significantly affect the accuracy of the prediction, i.e., the quality of the reviews. In this paper, we propose a regression model that explicitly takes into account the quality factor, and discusses how this quality information can be predicted when it is not readily available. Experimental results on a movie review dataset confirm the effectiveness of the proposed model.","Title: Scalable Distributed Processing of K Nearest Neighbor Queries over Moving Objects\nYear: 2015\n\nAbstract: Central to many applications involving moving objects is the task of processing k-nearest neighbor (k-NN) queries. Most of the existing approaches to this problem are designed for the centralized setting where query processing takes place on a single server; it is difficult, if not impossible, for them to scale to a distributed setting to handle the vast volume of data and concurrent queries that are increasingly common in those applications. To address this problem, we propose a suite of solutions that can support scalable distributed processing of k-NN queries. We first present a new index structure called Dynamic Strip Index (DSI), which can better adapt to different data distributions than exiting grid indexes. Moreover, it can be naturally distributed across the cluster, therefore lending itself well to distributed processing. We further propose a distributed k-NN search (DKNN) algorithm based on DSI. DKNN avoids having an uncertain number of potentially expensive iterations, and is thus more efficient and more predictable than existing approaches. DSI and DKNN are implemented on Apache S4, an open-source platform for distributed stream processing. We perform extensive experiments to study the characteristics of DSI and DKNN, and compare them with three baseline methods. Experimental results show that our proposal scales well and significantly outperforms the alternative methods.","Title: Weighted aspect-based collaborative filtering\nYear: 2014\n\nAbstract: Existing work on collaborative filtering (CF) is often based on the overall ratings the items have received. However, in many cases, understanding how a user rates each aspect of an item may reveal more detailed information about her preferences and thus may lead to more effective CF. Prior work has studied extracting/quantizing sentiments on different aspects from the reviews, based on which the unknown overall ratings are inferred. However, in that work, all the aspects are treated equally; while in reality, different users tend to place emphases on difference aspects when reaching the overall rating. For example, users may give a high rating to a movie just for its plot despite its mediocre performances. This emphasis on aspects varies for different users and different items. In this paper, we propose a method that uses tensor factorization to automatically infer the weights of different aspects in forming the overall rating. The main idea is to learn, through constrained optimization, a compact representation of a weight tensor indexed by three dimensions for user, item, and aspect, respectively. Overall ratings can then be predicted using the obtained weights. Experiments on a movie dataset show that our method compares favorably with three baseline methods.","Title: Continuous KNN Join Processing for Real-Time Recommendation\nYear: 2014\n\nAbstract: The explosive growth of user-generated contents in social networking websites necessitates the recommendation functionality that can push to the user the content that he/she is most likely to be interested in. Such recommendation should happen in real-time as new contents become available, because \"freshness\" is an important consideration in people's content-consumption behavior. Representing users and contents as feature vectors in a high-dimensional space, we can essentially cast the problem of real-time recommendations as the problem of computing the list of k nearest neighbors of each user, which we call kNN join. Given the vast volume of contents and users, the biggest challenge is how to continuously update the kNN join results as new contents arrive. Existing methods for incremental kNN join on data streams suffer from the \"curse of dimensionality\" and high in-memory search cost. In this paper, we present a solution that first identifies the users whose kNN's might be affected by the newly arrived content, and then update their kNN's respectively. We propose a new index structure named HDR-tree in order to support the efficient search of affected users. HDR-tree performs dimensionality reduction through clustering and principle component analysis (PCA) in order to improve the search effectiveness. To further reduce response time, we propose a variant of HDR-tree, called HDR-tree, that supports more efficient but approximate solutions. The results of extensive experiments show that our methods significantly outperform baseline methods.","Title: MeanKS: meaningful keyword search in relational databases with complex schema\nYear: 2014\n\nAbstract: Keyword search in relational databases was introduced in the last decade to assist users who are not familiar with a query language, the schema of the database, or the content of the data. An answer is a join tree of tuples that contains the query keywords. When searching a database with a complex schema, there are potentially many answers to the query. Therefore, ranking answers based on their relevance is crucial in this context. Prior work has addressed relevance based on the size of the answer or the IR scores of the tuples. However, this is not sufficient when searching a complex schema. We demonstrate MeanKS, a new system for meaningful keyword search over relational databases. The system first captures the user's interest by determining the roles of the keywords. Then, it uses schema-based ranking to rank join trees that cover the keyword roles. This uses the relevance of relations and foreign-key relationships in the schema over the information content of the database. In the demonstration, attendees can execute queries against the TPC-E warehouse and compare the proposed measures against a gold standard derived from a real workload over TPC-E to test the effectiveness of our methods.","Title: Signaling adverse drug reactions with novel feature-based similarity model\nYear: 2014\n\nAbstract: Adverse drug reactions (ADRs) are a main cause of hospitalization and deaths worldwide. These unanticipated episodes are generally infrequent, but almost all existing ADR signaling techniques are designed to use dataset extracted from spontaneous reporting systems or employed a predefined type of information (e.g., drugs), which suffer from failures to detect unexpected and latent ADRs. In this paper, we propose a novel Feature-based Similarity model (FS) to detect the potential ADRs for medical cases using the electronic patient dataset. FS is tested on the real patient data retrieved from the US Food Drug Administration that includes 54,070 patients detail information and 9,567 ADRs records. Our model ranked all ADRs for the given medical case that combined the information of drugs, medical conditions, and patient profiles and can be applied in therapy decision support systems and unexpected ADR warning systems. The experimental results show that FS outperforms comparing methods. This paper clearly illustrates the great potential along the new direction of ADR signal generate from health care administrative database.","Title: Ranking Keyword Search Results with Query Logs\nYear: 2014\n\nAbstract: Keyword search provides a uniform way of accessing the vast volume of structured and unstructured data present in many enterprises. Existing research on improving the effectiveness of the keyword search has largely focused on result ranking mechanisms, with little consideration given to user feedback. We are working towards developing a new approach to ranking the results of keyword search over structured data (stored in databases) using feedback information in the form of query logs. Our work is based on the schema-graph-based approach to keyword search, which consists of a candidate network (CN) generation phase and a CN evaluation phase. Our proposal is to extract the frequent patterns from the query log of a user (or a user group) and use them in ranking the CNs generated by the first phase. We present a concise description of our approach and lay out our plan for the next stage of research. Preliminary experiment results on a real dataset are also included.","Title: GrandLand Traffic Data Processing Platform\nYear: 2014\n\nAbstract: Recent years have seen an increasing number of traffic surveillance cameras deployed on the main roads and intersections of metropolitan areas. For large and ediumsized cities, these cameras generate an enormous amount of data. Existing solutions based relational database systems cannot effectively manage and process such large volume of data, nor can they provide support for efficient and scalable support for either analytical tasks or tasks requiring response in real-time. To address these challenges, we have developed the GrandLand Traffic Data Processing Platform (GLPlatform) to provide distributed, scalable processing of traffic surveillance data.","Title: Towards Efficient KNN Joins on Data Streams\nYear: 2014\n\nAbstract: We study the problem of efficient processing of kNN joins over high-dimensional data streams, which is an operation required by many big data applications. Specifically, we are concerned with the continuous evaluation of a set of k nearest neighbor queries Q on streams of high-dimensional items at consecutive snapshots of those streams. While one possible solution is to evaluate the kNN joins starting from scratch at each snapshot, it is too expensive for large volumes of data we encounter in big data applications. We consider the data stream on a time window and maintain the join results for Q at every snapshot in main memory. Our approach to this problem is to build indexes on Q, and only update the results of the queries affected by the changes in the streams at each snapshot. We propose a main-memory structure called the High-dimensional R-tree (HDR-tree) to index the queries, which is efficient in finding affected queries with reasonable maintenance cost. HDR-tree takes advantage of the benefit of clustering and the principle component analysis (PCA) technique. Preliminary experimental results show that our index structures significantly outperform baseline methods.","Title: Monitoring k-Nearest Neighbor Queries over Moving Objects\nYear: 2005\n\nAbstract: Many location-based applications require constant monitoring of k-nearest neighbor (k-NN) queries over moving objects within a geographic area. Existing approaches to this problem have focused on predictive queries, and relied on the assumption that the trajectories of the objects are fully predictable at query processing time. We relax this assumption, and propose two efficient and scalable algorithms using grid indices. One is based on indexing objects, and the other on queries. For each approach, a cost model is developed, and a detailed analysis along with the respective applicability are presented. The Object-Indexing approach is further extended to multi-levels to handle skewed data. We show by experiments that our grid-based algorithms significantly outperform R-tree-based solutions. Extensive experiments are also carried out to study the properties and evaluate the performance of the proposed approaches under a variety of settings.","Title: Efficient Duplication Free and Minimal Keyword Search in Graphs\nYear: 2014\n\nAbstract: Keyword search over a graph searches for a subgraph that contains a set of query keywords. A problem with most existing keyword search methods is that they may produce duplicate answers that contain the same set of content nodes (i.e., nodes containing a query keyword) although these nodes may be connected differently in different answers. Thus, users may be presented with many similar answers with trivial differences. In addition, some of the nodes in an answer may contain query keywords that are all covered by other nodes in the answer. Removing these nodes does not change the coverage of the answer but can make the answer more compact. The answers in which each content node contains at least one unique query keyword are called minimal answers in this paper. We define the problem of finding duplication-free and minimal answers, and propose algorithms for finding such answers efficiently. Extensive performance studies using two large real data sets confirm the efficiency and effectiveness of the proposed methods.","Title: Mining moving patterns for predicting next location\nYear: 2015\n\nAbstract: Next location prediction has been an essential task for many location based applications such as targeted advertising. In this paper, we present three basic models to tackle the problem of predicting next locations: the Global Markov Model that uses all available trajectories to discover global behaviors, the Personal Markov Model that focuses on mining the individual patterns of each moving object, and the Regional Markov Model that clusters the trajectories to mine the similar movement patterns. The three models are integrated with linear regression in different ways. We then seek to further improve the accuracy of prediction by considering the time factor, with a focus on clustering the trajectories in different time periods, and present three methods to train the time-aware models to mine periodic patterns. Therefore, our proposed models have the following advantages: (1) we consider both individual and collective movement patterns in making prediction, (2) we consider the similarity between different trajectories, (3) we consider the time factor and build models that are suited to different time periods. We have conducted extensive experiments on a real dataset, and the results demonstrate the superiority of our proposed models over existing methods. HighlightsWe propose three models (PMM, GMM and RMM) and combine them in different ways to obtain new models to predict the next location of a moving object.GMM uses all available trajectories to discover collective patterns; PMM models the individual patterns of each moving object using its own past trajectories; RMM clusters the trajectories to mine the movement patterns.Based on the observation that the movement patterns often change over time, we propose methods that can capture the relationships between the patterns in different time periods, and use this knowledge to build more refined models.To the best of our knowledge, the proposed models are the first ones that take a holistic approach and consider individual, collective movement patterns and the similarity between trajectories in making prediction.We conduct extensive experiments using a real dataset and the results demonstrate the effectiveness of the proposed models.","Title: A smartphone app framework for segmented cancer care coordination.\nYear: 2016\n\nAbstract: Complex cancer care requires careful coordination, but resource limitations result in lack of effective coordinated follow-up services. Recent advances in smartphones offer great opportunities for better segmentation of patient populations for cost-effective, targeted care coordination and monitoring or surveillance of cancer patients. This paper presents a framework of a smartphone app that provides such risk assessment and follow-up care monitoring services. This mHealth app framework includes three functional modules: a natural language processing module based on Bayesian model to extract relevant information from free text or medical reports; a cancer risk calculator that uses support vector machine classification to assess the medical risks of cancer patients based on the information extracted; and a health care monitor that provides timely care coordination to high risk cancer patients. The experimental results validate mHealth as a reliable medical risk assessment for post-surgical cancer patients and an effective health care monitoring service for cancer care coordination.","Title: Data security and privacy management in healthcare applications and clinical data warehouse environment\nYear: 2016\n\nAbstract: Health Information is considered the most sensitive information associated to an individual. Even though numerous suitable policies, guidelines, and compliance requirements are in place to safeguard health information, privacy and security breach remains key issues for electronic healthcare systems. In this paper we focus on these issues and propose a security and privacy model implemented in Methodist Environment for Translational and Outcomes Research (METEOR). METEOR was developed at Houston Methodist Hospital and consists of two components: the enterprise data warehouse (EDW) and a software intelligence and analytics (SIA) layer. This model indicates that patient privacy is best protected by implementing a systematic mix of technologies and best practices such as technical de-identification of data, restrictive data access, and security measures in the underlying technical platforms. Our results suggest that the proposed security model make data security compromise and unauthorized access of protected patient health information extremely improbable.","Title: Meaningful keyword search in relational databases with large and complex schema\nYear: 2015\n\nAbstract: Keyword search over relational databases offers an alternative way to SQL to query and explore databases that is effective for lay users who may not be well versed in SQL or the database schema. This becomes more pertinent for databases with large and complex schemas. An answer in this context is a join tree spanning tuples containing the query's keywords. As there are potentially many answers to the query, and the user is often only interested in seeing the top-k answers, how to rank the answers based on their relevance is of paramount importance. We focus on the relevance of join as the fundamental means to rank answers. We devise means to measure relevance of relations and foreign keys in the schema over the information content of the database. This can be done offline with no need for external models. We compare the proposed measures against a gold standard we derive from a real workload over TPC-E and evaluate the effectiveness of our methods. Finally, we test the performance of our measures against existing techniques to demonstrate a marked improvement, and perform a user study to establish naturalness of the ranking of the answers.","Title: Predicting Next Locations with Object Clustering and Trajectory Clustering\nYear: 2015\n\nAbstract: Next location prediction is of great importance for many location based applications. In many cases, understanding the similarity between objects and the similarity between trajectories may lead to more accurate predictions. In this paper, we propose two novel models exploiting these two types of similarities respectively. The first model, named object-clustered Markov model (object-MM), first clusters similar objects based on their spatial localities, and then builds variable-order Markov models with the trajectories of objects in the same cluster. The second model, named trajectory-clustered Markov model (tra-MM), considers the similarity between trajectories, and clusters the trajectories to form the training set used in building the Markov models. The two models are integrated to produce the final next location predictor (objectTra-MM). Experiments based on a real data set demonstrate significant increase in prediction accuracy of objectTra-MM over existing methods.","Title: A Plane Moving Average Algorithm for Short-Term Traffic Flow Prediction.\nYear: 2015\n\nAbstract: In this paper, a plane moving average algorithm is proposed for solving the urban road flow forecasting problem. This new approach assembles information from relevant traffic time series and has the following advantages: (1) it integrates both individual and similar flow patterns in making prediction, (2) the training data set does not need to be large, (3) it has more generalization capabilities in predicting unpredictable and much complex urban traffic flow than previously used methods. To assess the new model, we have performed extensive experiments on a real data set, and the results give evidence of its superiority over existing methods.","Title: Sentiment analysis of sentences with modalities\nYear: 2013\n\nAbstract: This paper is concerned with sentiment analysis of sentences with modality. Modality is a commonly occuring linguistic phenomenon. Due to its special characteristics, the sentiment borne by modality may be hard to determine by existing methods. We first present a linguistic analysis of modality, and then identify some valuable features to train a support vector machine classifier to determine the sentiment orientation of such sentences. We show experimental results on sentences with modality that are extracted from the reviews of four different products to illustrate the effectiveness of the proposed method.","Title: Mining Object Similarity for Predicting Next Locations.\nYear: 2016\n\nAbstract: Next location prediction is of great importance for many location-based applications. With the virtue of solid theoretical foundations, Markov-based approaches have gained success along this direction. In this paper, we seek to enhance the prediction performance by understanding the similarity between objects. In particular, we propose a novel method, called weighted Markov model (weighted-MM), which exploits both the sequence of just-passed locations and the object similarity in mining the mobility patterns. To this end, we first train a Markov model for each object with its own trajectory records, and then quantify the similarities between different objects from two aspects: spatial locality similarity and trajectory similarity. Finally, we incorporate the object similarity into the Markov model by considering the similarity as the weight of the probability of reaching each possible next location, and return the top-rankings as results. We have conducted extensive experiments on a real dataset, and the results demonstrate significant improvements in prediction accuracy over existing solutions.","Title: VColor: A practical vertex-cut based approach for coloring large graphs\nYear: 2016\n\nAbstract: Graph coloring is a fundamental NP-hard problem in graph theory. It has a wide range of real applications, such as Operations Research, Communication Network, Computational Biology and Compiler Optimization. Notable efforts have been spent on designing its approximation algorithms. Halldrsson proposed the algorithm (denoted as SampleIS) with the current best known approximation ratio. However, its time complexity is O(|G|3), where |G| is the number of vertices of a graph G. It is clear that SampleIS is not practical for large graphs. In this paper, we propose a practical vertex-cut based coloring technique (VColor) for coloring large graphs. First, we partition G into k connected components (CCs) of a small size s by removing a vertex-cut component (VCC). For each CC, we apply our novel coloring algorithm, based on maximal independent set enumeration. The approximation ratio and the time complexity for coloring the k CCs are log s + 1 and O(ks23s/3), respectively, whereas those of SampleIS are ks(log log ks)2/ log3 ks and O(k3s3). For the VCC, we simply apply SampleIS. To combine the colorings of the CCs and the VCC, we propose a maximum matching based algorithm. Second, in the context of a database of graphs, users may color many graphs. We propose an optimization technique, inspired by multi-query optimization, for coloring a set of graphs. We design a VP hierarchy (VPH) to represent the common subgraphs as the common CCs. Third, we propose techniques for determining the optimal values of the parameters of VColor. Our extensive experimental evaluation on real-world graphs confirms the efficiency and/or effectiveness of our proposed techniques. In particular, VColor is more than 500 times faster than SampleIS, and the number of colors used are comparable on real graphs Yeast and LS.","Title: Privacy-Preserving Reachability Query Services for Massive Networks\nYear: 2016\n\nAbstract: This paper studies privacy-preserving reachability query services under the paradigm of data outsourcing. Specically, graph data have been outsourced to a third-party service provider (SP), query clients submit their queries to the SP, and the SP returns the query answers to the clients. However, the SP may not always be trustworthy. Therefore, this paper investigates protecting the structural information of the graph data and the query answers from the SP. Existing techniques are either insecure or not scalable. This paper proposes a privacy-preserving labeling, called ppTopo. To our knowledge, ppTopo is the first work that can produce reachability index on massive networks and is secure against known plaintext attacks (KPA). Specifically, we propose an index construction algorithm for private reachability queries, by employing the idea of topological folding, recently proposed by Cheng et al. We propose a novel asymmetric scalar product encryption in modulo 3 (ASPE3). It allows us to encrypt the labels and transforms the queries into scalar products of encrypted labels. We perform an experimental study of the proposed technique on the datasets of SNAP networks. Compared with the existing methods, our results show that our technique is capable of producing the encrypted indexes at least 5 times faster for massive networks and the client's decryption time is 2-3 times smaller for most graphs. We also propose the heuristic optimization to reduce the size of index.","Title: Collaborative filtering with weighted opinion aspects.\nYear: 2016\n\nAbstract: Collaborative filtering (CF) aims to produce recommendations based on other users' ratings to an item. Most existing CF methods rely on the overall ratings an item has received. However, these ratings alone sometimes cannot provide sufficient information to understand users' behaviors. For example, a user giving a high rating may indicate that he loves the item as a whole; however, it is still likely that he dislikes some particular aspects at the same time. In addition, users tend to place different emphases on different aspects when reaching an overall rating. This emphasis on aspects may even vary from users to items, and has a significant impact on a user's final decision. To make a better understanding of a user' behavior and generate a more accurate recommendation, we propose a framework that incorporates both user opinions and preferences on different aspects. This framework is composed of three components, namely, an opinion mining component, an aspect weighting computing component, and a rating inference component. The first component exploits opinion mining techniques to extract and summarize opinions on multiple aspects from reviews, and generates ratings on various aspects. The second component applies a tensor factorization strategy to automatically infer weights of different aspects in reaching an overall rating. The last one infers the overall rating of an item based on both aspect ratings and weights. Experiments on two real datasets prove that our model performs better compared with the baseline methods.","Title: Repair Singleton IDs on the Fly.\nYear: 2016\n\nAbstract: Tracking moving entities at predefined locations plays an essential role in many surveillance related applications. Occasionally, the IDs of those entities are incorrectly recorded due to various reasons such as errors in recognition. Such errors need to be repaired on the fly as those IDs are often involved in some time-sensitive query processing or data analysis tasks. In this paper, we address a specific case where the errors result in singleton IDs, i.e., IDs that appear only once during a specific period of time and thus could be safely presumed to be erroneous. The repair of the IDs is based on constraints posed by the data itself (e.g., constraints posed by the road network). We present a tracking tree structure to index the candidate repairs for each singleton ID, which enables repairing of the IDs on the fly. We implement a distributed repair system on the Apache Storm platform. Experiments on both real and synthetic datasets demonstrate the effectiveness and efficiency of our singleton detection and repair approach.","Title: Spica: A Path Bundling Model for Rational Route Recommendation.\nYear: 2016\n\nAbstract: This paper presents Spica, a path bundling model for rational route recommendation leveraging the intelligence and experience of the past driving records. In this model, the traffic surveillance system is employed to probe the traffic rhythm of a city and vehicle traveling record’s intelligence is used to choose driving directions in the real world. We propose Joint Technique (JT) to build Time-Dependent Joint (TDJ) graph and model the dynamic traffic pattern so as to provide the rational fastest route to a given destination at a given starting time. Then we estimate the travel time in different time slots and based on TDJ graph, we propose Time-Dependent Heuristic Algorithm (TDHA) to compute the rational recommended routes. We build our model based on a real-world trajectory data set generated by totally 44,593,706 passage records in a period of a week, and evaluate the performance of our model by conducting extensive experiments. The recommended routes are effective and JT gives evidence of its rationality over previous ways.","Title: KEIPD: Knowledge Extraction and Inference System for Personal Documents.\nYear: 2016\n\nAbstract: Public personal documents on the Internet, such as resumes and personal homepages, may imply social relationships among people, which is of great value in various applications. This paper presents KEIPD, a system to extract and infer knowledge from personal documents. KEIPD employs a tree-similarity based approach to extract information from personal documents to obtain a relational network of entities. Then the inference of social relationships can be transformed into a link prediction problem. KEIPD implements some popular unsupervised predictors for link prediction and prune the candidate entity pairs based on the domain-dependent constraint.","Title: Distributed Top-k Keyword Search over Very Large Databases with MapReduce\nYear: 2016\n\nAbstract: In the last decade, keyword search over relational databases has been extensively studied because it promises to allow users lacking knowledge of structured query languages or unaware of the database schema to query the database in an intuitive way. The existing works about keyword search on databases proposed many approaches and have gain remarkable results. However, most of these approaches are designed for the centralized setting where keyword search is processed by only a single server. In reality, the scale of databases increases sharply and centralized methods hardly can handle keyword queries over these large databases. Moreover, processing keyword search over relational databases is a very time-consuming task, and the efficiency of the existing centralized approaches will degrade notably because the single server cannot provide enough computation power for the keyword search over very large databases. To address these challenges, we propose a distributed keyword search (DKS) approach with MapReduce and this approach can be well deployed on a cluster of servers to deal with keyword search over large databases in a parallel way.","Title: CI-Rank: Collective importance ranking for keyword search in databases.\nYear: 2017\n\nAbstract: Keyword search over databases, popularized by keyword search in WWW, allows ordinary users to access database information without the knowledge of structured query languages and database schemas. Most of the previous studies in this area use IR-style ranking, which fail to consider the importance of the query answers. In this paper, we propose CI-Rank, a new approach to keyword search in databases, which considers the importance of individual nodes in a query answer and the cohesiveness of the result structure in a balanced way. CI-Rank is built upon a carefully designed model called Random Walk with Message Passing that helps capture the relationships between different nodes in the query answer. This model lends itself well to adaptation to user preferences. We develop a branch and bound algorithm to support the efficient generation of top-k query answers. Indexing methods are also introduced to further speed up the run-time processing of queries. Extensive experiments conducted on two real data sets with a real user query log confirm the effectiveness and efficiency of CI-Rank.","Title: Weighted Co-Training for Cross-Domain Image Sentiment Classification.\nYear: 2017\n\nAbstract: Image sentiment classification, which aims to predict the polarities of sentiments conveyed by the images, has gained a lot of attention. Most existing methods address this problem by training a general classifier with certain visual features, ignoring the discrepancies across domains. In this paper, we propose a novel weighted co-training method for cross-domain image sentiment classification, which iteratively enlarges the labeled set by introducing new high-confidence classified samples to reduce the gap between the two domains. We train two sentiment classifiers with both the images and the corresponding textual comments separately, and set the similarity between the source domain and the target domain as the weight of a classifier. We perform extensive experiments on a real Flickr dataset to evaluate the proposed method, and the empirical study reveals that the weighted co-training method significantly outperforms some baseline solutions.","Title: A Fuzzy Owen function on games with coalition structure and fuzzy coalitions.\nYear: 2017\n\nAbstract: In this paper, a game with coalition structure and fuzzy coalitions is introduced, which can be regarded as an extension of the game with coalition structure. Firstly, an Owen function is defined. Then, the unique explicit form of the Owen function is given by extending the Owen value. Secondly, as an extension of Owen function, a fuzzy Owen function is proposed. In addition, an explicit form of the fuzzy Owen function is given by considering the fuzzy intermediate game with Owen extension form. Finally, an illustrate example is provided to illustrate the allocation method of gains.","Title: Characteristics of Evapotranspiration of Urban Lawns in a Sub-Tropical Megacity and Its Measurement by the 'Three Temperature Model + Infrared Remote Sensing' Method.\nYear: 2017\n\nAbstract: Evapotranspiration (ET) is one of the most important factors in urban water and energy regimes. Because of the extremely high spatial heterogeneity of urban area, accurately measuring ET using conventional methods remains a challenge due to their fetch requirements and low spatial resolution. The goals of this study were to investigate the characteristics of urban ET and its main influencing factors and subsequently to improve a fetch-free, high spatial resolution method for urban ET estimation. The Bowen ratio and the 'three-temperature model (3T model) + infrared remote sensing (RS)' methods were used for these purposes. The results of this study are listed in the following lines. (1) Urban ET is mainly affected by solar radiation and the effects of air humidity, wind velocity, and air temperature are very weak; (2) The average daily, monthly, and annual ETs of the urban lawn are 2.70, 60-100, and 990 mm, respectively, which are obvious compared with other landscapes; (3) The ratio of ET to precipitation is 0.65 in the wet season and 2.6 in the dry season, indicating that most of the precipitation is evaporated; (4) The fetch-free approach of '3T model + infrared RS' is verified to be an accurate method for measuring urban ET and it agrees well with the Bowen ratio method (R-2 is over 0.93 and the root mean square error is less than 0.04 mm h(-1)); (5) The spatial heterogeneity of urban ET can also be accurately estimated by the proposed approach. These results are helpful for improving the accuracy of ET estimation in urban areas and are useful for urban water and environmental planning and management.","Title: The fuzzy bargaining set of cooperative game with fuzzy coalition.\nYear: 2017\n\nAbstract: In this paper, the fuzzy bargaining set of cooperative game with fuzzy coalition is proposed, which can be regarded as the generalization of crisp bargaining set. The fuzzy bargaining set is based on the assumption that the total worth of a fuzzy coalition will be allocated to the players whose participation rate is larger than zero. Because fuzzy core had been proposed as a kind of solution for the fuzzy games, the relationship between fuzzy bargaining set and fuzzy core is also showed. Surprisingly, the relationship between fuzzy bargaining set and fuzzy core does coincide as in the classical case. The property of fuzzy bargaining set is also analyzed, such as the existence condition of counter-objection.","Title: Lce: A Location Category Embedding Model For Predicting The Category Labels Of Pois\nYear: 2017\n\nAbstract: The proliferation of location-based social networks, makes it possible to record human mobility using an array of points-of-interest (POIs). Exploring the semantic meanings of POIs can be of great importance to many urban computing applications, e.g., personalized route recommendation and user trajectory clustering. Nonetheless, such information is not always available in practice. This paper aims at predicting the category labels, which will provide a succinct summarization of POIs. In particular, we first propose a Location Category Embedding (LCE) model, which projects user POIs and their associated category labels into the same vector space, and then identify the POIs' most related category labels according to their similarities. To capture the influence that might affect users' moving behavior, LCE considers sequential pattern, personal preference, and temporal influence, and further models the connection between the POIs and the three factors. Experimental results on two real-world datasets prove the effectiveness of the proposed method.","Title: Cooperative game with fuzzy coalition and payoff value in the generalized integral form.\nYear: 2017\n\nAbstract: In this paper, a new class of games with fuzzy coalitions and fuzzy payoff value is proposed. This class of fuzzy games is based on the generalized integral form, which contains several kinds of other fuzzy games, such as fuzzy cooperative game with fuzzy payoff value, the multilinear extension game introduced by Owen, the game with proportional value proposed by Butnariu and the game with Choquet integral form given by Tsurumi et al. Also, the proposed fuzzy game is also further extension of the fuzzy game in Choquet integral form proposed by Yu et al., which is also is a kind of fuzzy games in the condition that coalition and fuzzy payoff value are both fuzzy information. The fuzzy Shapley value for this kind of fuzzy games is represented by Shapley value of corresponding fuzzy cooperative game with fuzzy payoff value. Based on Hukuhara-difference, we give the explicit Shapley value for the proposed fuzzy game. It has been seen that most of properties hold well in the proposed fuzzy game, which are processed by cooperation game with fuzzy payoff value, and fuzzy coalition game, respectively. Finally, a practical application of the proposed model is also provided.","Title: A PSO-Powell Hybrid Method to Extract Fiber Orientations from ODF.\nYear: 2018\n\nAbstract: High angular resolution diffusion imaging (HARDI) has opened up new perspectives for the delineation of crossing and branching fiber pathways by orientation distribution function (ODF). The fiber orientations contained in an imaging voxel are the key factor in tractography. To extract real fiber orientations from ODF, a hybrid method is proposed for computing the principal directions of ODF by combining the variation of Particle Swarm Optimization (PSO) algorithm with the modified Powell algorithm. This method is comprised of the global searching ability of PSO and the powerful local optimizing of Powell search. This combination can guarantee finding all the diffusion directions without applying sliding windows and improve the accuracy and efficiency. The proposed approach was evaluated on simulated crossing-fiber datasets, Tractometer, and in vivo datasets. The results show that this method could correctly identify fiber directions under a range of noise levels. This method was compared with the state-of-the-art methods, such as modified Powell, ball-stick model, and diffusion decomposition, showing that it outperformed them. As to the multimodal voxels where different fiber populations exist, the proposed approach allows us to improve the estimation accuracy of fiber orientations from ODF. It can play a significant role in the nerve fiber tracking.","Title: A Perception-Driven Approach to Supervised Dimensionality Reduction for Visualization.\nYear: 2018\n\nAbstract: Dimensionality reduction (DR) is a common strategy for visual analysis of labeled high-dimensional data. Low-dimensional representations of the data help, for instance, to explore the class separability and the spatial distribution of the data. Widely-used unsupervised DR methods like PCA do not aim to maximize the class separation, while supervised DR methods like LDA often assume certain spatial...","Title: Model-based Clustering of Short Text Streams.\nYear: 2018\n\nAbstract: Short text stream clustering has become an increasingly important problem due to the explosive growth of short text in diverse social medias. In this paper, we propose a model-based short text stream clustering algorithm (MStream) which can deal with the concept drift problem and sparsity problem naturally. The MStream algorithm can achieve state-of-the-art performance with only one pass of the stream, and can have even better performance when we allow multiple iterations of each batch. We further propose an improved algorithm of MStream with forgetting rules called MStreamF, which can efficiently delete outdated documents by deleting clusters of outdated batches. Our extensive experimental study shows that MStream and MStreamF can achieve better performance than three baselines on several real datasets.","Title: A review of anisotropic conductivity models of brain white matter based on diffusion tensor imaging.\nYear: 2018\n\nAbstract: The conductivity of brain tissues is not only essential for electromagnetic source estimation (ESI), but also a key reflector of the brain functional changes. Different from the other brain tissues, the conductivity of whiter matter (WM) is highly anisotropic and a tensor is needed to describe it. The traditional electrical property imaging methods, such as electrical impedance tomography (EIT) and magnetic resonance electrical impedance tomography (MREIT), usually fail to image the anisotropic conductivity tensor of WM with high spatial resolution. The diffusion tensor imaging (DTI) is a newly developed technique that can fulfill this purpose. This paper reviews the existing anisotropic conductivity models of WM based on the DTI and discusses their advantages and disadvantages, as well as identifies opportunities for future research on this subject. It is crucial to obtain the linear conversion coefficient between the eigenvalues of anisotropic conductivity tensor and diffusion tensor, since they share the same eigenvectors. We conclude that the electrochemical model is suitable for ESI analysis because the conversion coefficient can be directly obtained from the concentration of ions in extracellular liquid and that the volume fraction model is appropriate to study the influence of WM structural changes on electrical conductivity. Graphical abstract ᅟ.","Title: Linear fuzzy game with coalition interaction and its coincident solutions.\nYear: 2018\n\nAbstract: In this study, we consider the solution concepts for fuzzy coalition games (i.e., cooperative games with fuzzy coalition) under a certain participation level. In general, cooperative games with fuzzy coalition are based on the assumption that all the fuzzy coalition values for different fuzzy coalitions must be represented by the same formula, which may omit the coalition interaction under different participation ratios for players. Considering these conditions, we propose the coincident fuzziness form for games with fuzzy coalition, which are represented by a mapping from the characteristic function of the crisp game to that of the fuzzy coalition game. The proposed fuzzy coalition games admit the differences in coalition interactions for different fuzzy coalitions, where the coalition interactions are represented by the fuzzy coalition values in different ways (or formulas). For a fixed fuzzy coalition, the maximum fuzzy coalition game is proven to be the Choquet integral form on the condition that the associate crisp game is convex. In order to seek appropriate solutions for the proposed games based on a certain participation level, the Fuzzy-Shapley axioms are defined, and the explicit Shapley value is represented by the Shapley value of the associated crisp games. Moreover, the fuzzy core of this proposed fuzzy coalition game is the stable solution set for the given fuzzy coalition, which is also denoted by the crisp cores. Furthermore, we study the relationship between the Fuzzy-Shapley value and the fuzzy core. By adding restrictions on the fuzzy core, we propose a strong Fuzzy-core, which is a more stable solution than the fuzzy core. In addition, the fuzzy core is equivalent to the strong Fuzzy-core under some condition.","Title: PCNN: Deep Convolutional Networks for Short-Term Traffic Congestion Prediction.\nYear: 2018\n\nAbstract: Traffic problems have seriously affected people's life quality and urban development, and forecasting short-term traffic congestion is of great importance to both individuals and governments. However, understanding and modeling the traffic conditions can be extremely difficult, and our observations from real traffic data reveal that: 1) similar traffic congestion patterns exist in the neighboring ...","Title: The extended Shapley value for generalized cooperative games under precedence constraints\nYear: 2020\n\nAbstract: We introduce a new class of games where cooperation among players is restricted by precedence constraints vis á vis the worth of a coalition depends on the order in which the players enter into the coalition. The idea combines two existing classes of cooperative games, namely the cooperative games under precedence constraints due to Faigle and Kern (Int J Game Theory 21(3):249–266, 1992) and the games in generalized characteristic function due to Nowak and Radzik (Games Econ Behav 6(1):150–161, 1994). A Shapley value for this special class of games is proposed, we call it the extended Shapley value to distinguish it for the existing one. Two axiomatic characterizations of the extended Shapley value are given: one uses Efficiency, Null player, and Linearity; the other uses Efficiency, Marginality, and Null game. Some interesting properties of the extended Shapley value are studied. Furthermore, two extensions of the extended Shapley value, called the extended probabilistic value and the extended order value, are proposed and characterized. Our study shows that the results in cooperative games under precedence constraints cannot have a trivial extension to the generalized constrained games and conversely.","Title: MPE: a mobility pattern embedding model for predicting next locations\nYear: 2019\n\nAbstract: The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each record having at least three attributes: object ID, location ID, and time-stamp. In this paper, we propose a novel mobility pattern embedding model called MPE to shed the light on people’s mobility patterns in traffic trajectory data from multiple aspects, including sequential, personal, and temporal factors. MPE has two salient features: (1) it is capable of casting various types of information (object, location and time) to an integrated low-dimensional latent space; (2) it considers the effect of “phantom transitions” arising from road networks in traffic trajectory data. This embedding model opens the door to a wide range of applications such as next location prediction and visualization. Experimental results on two real-world datasets show that MPE is effective and outperforms the state-of-the-art methods significantly in a variety of tasks.","Title: An efficient index structure for distributed k-nearest neighbours query processing\nYear: 2020\n\nAbstract: Many location-based services are supported by the moving k-nearest neighbour (k-NN) query, which continuously returns the k-nearest data objects for a query point. Most of existing approaches to this problem have focused on a centralized setting, which show poor scalability to work around massive-scale and distributed data sets. In this paper, we propose an efficient distributed solution for k-NN query over moving objects to tackle the increasingly large scale of data. This approach includes a new grid-based index called Block Grid Index (BGI), and a distributed k-NN query algorithm based on BGI. There are three advantages of our approach: (1) BGI can be easily constructed and maintained in a distributed setting; (2) the algorithm is able to return the results set in only two iterations. (3) the efficiency of k-NN query is improved. The efficiency of our solution is verified by extensive experiments with millions of nodes.","Title: Sliding Window Top-<Emphasis Type=\"Italic\">K</Emphasis> Monitoring over Distributed Data Streams\nYear: 2017\n\nAbstract: Most of the traditional top-k algorithms are based on a single-server setting. They may be highly inefficient and/or cause huge communication overhead when applied to a distributed system environment. Therefore, the problem of top-k monitoring in distributed environments has been intensively investigated recently. This paper studies how to monitor the top-k data objects with the largest aggregate numeric values from distributed data streams within a fixed-size monitoring window W, while minimizing communication cost across the network. We propose a novel algorithm, which adaptively reallocates numeric values of data objects among distributed nodes by assigning revision factors when local constraints are violated and keeps the local top-k result at distributed nodes in line with the global top-k result. We also develop a framework that combines a distributed data stream monitoring architecture with a sliding window model. Based on this framework, extensive experiments are conducted on top of Apache Storm to verify the efficiency and scalability of the proposed algorithm.","Title: An efficient index structure for distributed <Emphasis Type=\"Italic\">k</Emphasis>-nearest neighbours query processing\nYear: 2020\n\nAbstract: Many location-based services are supported by the moving k-nearest neighbour (k-NN) query, which continuously returns the k-nearest data objects for a query point. Most of existing approaches to this problem have focused on a centralized setting, which show poor scalability to work around massive-scale and distributed data sets. In this paper, we propose an efficient distributed solution for k-NN query over moving objects to tackle the increasingly large scale of data. This approach includes a new grid-based index called Block Grid Index (BGI), and a distributed k-NN query algorithm based on BGI. There are three advantages of our approach: (1) BGI can be easily constructed and maintained in a distributed setting; (2) the algorithm is able to return the results set in only two iterations. (3) the efficiency of k-NN query is improved. The efficiency of our solution is verified by extensive experiments with millions of nodes.","Title: Top-k Queries over Digital Traces\nYear: 2019\n\nAbstract: Recent advances in social and mobile technology have enabled an abundance of digital traces (in the form of mobile check-ins, association of mobile devices to specific WiFi hotspots, etc.) revealing the physical presence history of diverse sets of entities (e.g., humans, devices, and vehicles). One challenging yet important task is to identify k entities that are most closely associated with a given query entity based on their digital traces. We propose a suite of indexing techniques and algorithms to enable fast query processing for this problem at scale. We first define a generic family of functions measuring the association between entities, and then propose algorithms to transform digital traces into a lower-dimensional space for more efficient computation. We subsequently design a hierarchical indexing structure to organize entities in a way that closely associated entities tend to appear together. We then develop algorithms to process top-k queries utilizing the index. We theoretically analyze the pruning effectiveness of the proposed methods based on a mobility model which we propose and validate in real life situations. Finally, we conduct extensive experiments on both synthetic and real datasets at scale, evaluating the performance of our techniques both analytically and experimentally, confirming the effectiveness and superiority of our approach over other applicable approaches across a variety of parameter settings and datasets.","Title: Efficient Construction Of Nonlinear Models Over Normalized Data\nYear: 2021\n\nAbstract: Machine Learning (ML) applications are proliferating in the enterprise. Relational data which are prevalent in enterprise applications are typically normalized; as a result, data has to be denormalized via primary/foreign-key joins to be provided as input to ML algorithms. In this paper, we study the implementation of popular nonlinear ML models, Gaussian Mixture Models (GMM) and Neural Networks (NN), over normalized data addressing both cases of binary and multi-way joins over normalized relations.For the case of GMM, we show how it is possible to decompose computation in a systematic way both for binary joins and for multi-way joins to construct mixture models. We demonstrate that by factoring the computation, one can conduct the training of the models much faster compared to other applicable approaches, without any loss in accuracy.For the case of NN, we propose algorithms to train the network taking normalized data as the input. Similarly, we present algorithms that can conduct the training of the network in a factorized way and offer performance advantages. The redundancy introduced by denormalization can be exploited for certain types of activation functions. However, we demonstrate that attempting to explore this redundancy is helpful up to a certain point; exploring redundancy at higher layers of the network will always result in increased costs and is not recommended.We present the results of a thorough experimental evaluation, varying several parameters of the input relations involved and demonstrate that our proposals for the training of GMM and NN yield drastic performance improvements typically starting at 100%, which become increasingly higher as parameters of the underlying data vary, without any loss in accuracy.","Title: LES3: learning-based exact set similarity search\nYear: 2021\n\nAbstract: AbstractSet similarity search is a problem of central interest to a wide variety of applications such as data cleaning and web search. Past approaches on set similarity search utilize either heavy indexing structures, incurring large search costs or indexes that produce large candidate sets. In this paper, we design a learning-based exact set similarity search approach, LES3. Our approach first partitions sets into groups, and then utilizes a light-weight bitmap-like indexing structure, called token-group matrix (TGM), to organize groups and prune out candidates given a query set. In order to optimize pruning using the TGM, we analytically investigate the optimal partitioning strategy under certain distributional assumptions. Using these results, we then design a learning-based partitioning approach called L2P and an associated data representation encoding, PTR, to identify the partitions. We conduct extensive experiments on real and synthetic datasets to fully study LES3, establishing the effectiveness and superiority over other applicable approaches.","Title: An Intelligent Augmented Lifelike Avatar App for Virtual Physical Examination of Suspected Strokes\nYear: 2021\n\nAbstract: An intelligent-augmented lifelike avatar mobile app (iLAMA) that integrates computer vision and sensor readings to automate and streamline the NIH Stroke Scale (NIHSS) physical examination is presented. The user interface design is optimized for elderly patients while the app showcases an animated lifelike 3D model of a friendly physician who walks the user through the exam. The standardized NIHSS examination included in iLAMA consists of five core tasks. The first two tasks involve rolling the eyes to the left and then to the right, and then smiling as wide as the user can. The app determines facial landmarks and analyzes the palsy of the face. The next task is to extend the arm and hold the phone at the shoulder level, and the smart phone gyroscope is used to detect acceleration to determine possible weakness in the arm. Next, the app tracks the location of the hand keypoints and determines possible ataxia based on the precision and accuracy of the locations of the touches. Finally, the app determines the user's forward acceleration in walking and possible imbalances using the accelerometer. The app then sends analyzed results of these tasks to the neurologist or stroke specialist for review and decisions.","Title: Enabling the interpretability of pretrained venue representations using semantic categories\nYear: 2022\n\nAbstract: The growing popularity of location-based social networks gives rise to a tremendous amount of social check-ins data, which are broadly used in previous studies to produce dense venue representations for various trajectory mining tasks. In this work, we focus on the interpretability of venue representations, an essential property that existing methods fail to provide. We propose two novel models to generate interpretable and easy-to-understand venue representations. The first model, CEM, is a category-aware (a category may be a restaurant, a mall, etc.) check-in embedding model and generates venue and category representations by capturing the sequential patterns of check-in records. With the second model, XEM, each dimension of the venue representation corresponds to a semantic anchor (i.e., a category) and can be interpreted as a coherent topic. We conduct extensive experiments using real-world check-in datasets for venue similarity computation and venue semantic annotation, and empirically show that introducing interpretability to the venue representations improves the performance of various downstream tasks.","Title: PR-LTTE: Link travel time estimation based on path recovery from large-scale incomplete trip data\nYear: 2022\n\nAbstract: •Estimate link travel time with large-scale incomplete vehicle trip data.•Propose a path-recovery-based method to iteratively estimate link travel time.•Conduct extensive experiments on two public large-scale vehicle trip datasets.","Title: Embedding Hierarchical Structures for Venue Category Representation\nYear: 2022\n\nAbstract: AbstractVenue categories used in location-based social networks often exhibit a hierarchical structure, together with the category sequences derived from users’ check-ins. The two data modalities provide a wealth of information for us to capture the semantic relationships between those categories. To understand the venue semantics, existing methods usually embed venue categories into low-dimensional spaces by modeling the linear context (i.e., the positional neighbors of the given category) in check-in sequences. However, the hierarchical structure of venue categories, which inherently encodes the relationships between categories, is largely untapped. In this article, we propose a venue Category Embedding Model named Hier-CEM, which generates a latent representation for each venue category by embedding the Hierarchical structure of categories and utilizing multiple types of context. Specifically, we investigate two kinds of hierarchical context based on any given venue category hierarchy and show how to model them together with the linear context collaboratively. We apply Hier-CEM to three tasks on two real check-in datasets collected from Foursquare. Experimental results show that Hier-CEM is better at capturing both semantic and sequential information inherent in venues than state-of-the-art embedding methods.","Title: CAVE-SC: Inferring categories for venues using check-ins\nYear: 2022\n\nAbstract: The categories of venues are labels, such as Museum and Bar, assigned to geographic locations. They are often incomplete and new venues may constantly arise, making automatic venue labeling essential. In this study, we proposed a category-aware venue embedding model with similarity constraints (CAVE-SC), which is an automatic feature engineering method to infer category labels for venues. CAVE-SC first models the co-occurrence relations between a given venue and its two types of sequential contexts (namely, the venue context and the category context) based on a softmax loss and then projects both venues and categories into the same latent space. Furthermore, CAVE-SC models the similarity constraints posed by the relationships between venues and their categories based on a newly designed triplet loss, assuming that the distance between a venue and its category is smaller than the distance between the venue and a randomly sampled category in the embedding space. Finally, linear interpolation is used to balance the two losses, thereby generating discriminative feature representations of venues. Venue labeling can be performed based on the distances between venue representations and category representations. Extensive experiments on two check-in datasets demonstrate the superiority of CAVE-SC over the baseline methods.","Title: Ranked Window Query Retrieval over Video Repositories\nYear: 2022\n\nAbstract: Recent advances in Computer Vision have contributed to solid accuracy and efficiency improvements in many tasks such as object detection and tracking, enabling new opportunities for video analytics. In this paper, we initiate the study of ranked window queries that aim to retrieve clips from large video repositories in which objects co-occur in a queryspecified fashion. For example, ranked window queries allow retrieval of clips of a set duration (e.g., 10 seconds) with the highest score from a long video, where at least the same 3 cars (with matching conditions based on suitably defined metadata) appear jointly. To answer such queries, we propose a two-phased approach, which builds indexes for all desired objects of the given videos during an Ingestion Phase and evaluates query answers efficiently in the Query Phase. During the Ingestion Phase, the proposed Partition-Based Index Construction (PBIC) algorithm builds indexes on partitions obtained by splitting each given video. Leveraging such indexes, queries are answered in the Query Phase using the Partition-Based Query Processing (PBQP) algorithm, which efficiently produces the desired (queryspecified) number of results with the highest scores. We present the outcome of a thorough performance study on real videos that evaluates the performance of the proposed algorithms by varying parameters of interest. Our results indicate that the proposed set of techniques are capable of processing queries efficiently at scale, demonstrating multiple orders of magnitude speedups over other applicable approaches."],"string":"[\n \"Title: HadoopRsync\\nYear: 2011\\n\\nAbstract: Cloud storage has become increasingly popular due to its convenience, cost-effectiveness and scalability. It provides the basis for a slate of file hosting services, which offer users the ability to synchronize their files between the servers and their devices. Naive file synchronization, however, requires the whole file to be transmitted to all other locations (servers, devices) whenever the file is updated in one location. This leads to massive waste of bandwidth and significant delays in propagating the update. We propose a method called HadoopRsync, which is capable of performing incremental update of files instead of transmitting them in entirety. This method is based on the rsync utility originally proposed for file synchronization between computers, but the scenario under consideration is significantly different from that for rsync in that in the cloud storage context, files are distributedly stored at multiple nodes in the cloud. We therefore propose a pair of algorithms called HadoopRsync Upload and HadoopRsync Download, which are responsible for the synchronization from the user's devices to the cloud and the synchronization in the opposite direction respectively. These algorithms only transmit the differences between the new version of the file and the old version, rather than the whole file. Our solution is based on Hadoop, the open-source framework for distributed processing of very large data across clusters of computers. The algorithms utilize the MapReduce facility provided by Hadoop to fully taking advantage of its massive-parallelization capability. In addition, we propose some optimization measures to reduce the I/Os required for file update. Extensive experiments are conducted to evaluate the proposed solution, which show that HadoopRsync significantly outperforms the baseline methods.\",\n \"Title: Keyword query cleaning\\nYear: 2008\\n\\nAbstract: Unlike traditional database queries, keyword queries do not adhere to predefined syntax and are often dirty with irrelevant words from natural languages. This makes accurate and efficient keyword query processing over databases a very challenging task. In this paper, we introduce the problem of query cleaning for keyword search queries in a database context and propose a set of effective and efficient solutions. Query cleaning involves semantic linkage and spelling corrections of database relevant query words, followed by segmentation of nearby query words such that each segment corresponds to a high quality data term. We define a quality metric of a keyword query, and propose a number of algorithms for cleaning keyword queries optimally. It is demonstrated that the basic optimal query cleaning problem can be solved using a dynamic programming algorithm. We further extend the basic algorithm to address incremental query cleaning and top-k optimal query cleaning. The incremental query cleaning is efficient and memory-bounded, hence is ideal for scenarios in which the keywords are streamed. The top-k query cleaning algorithm is guaranteed to return the best k cleaned keyword queries in ranked order. Extensive experiments are conducted on three real-life data sets, and the results confirm the effectiveness and efficiency of the proposed solutions.\",\n \"Title: Alternative Query Optimization for Workload Management.\\nYear: 2012\\n\\nAbstract: Systems with heavy workloads run many queries concurrently. Modern database workloads-as those incurred by business intelligence applications-involve ad-hoc, highly complex, expensive queries. While query plans are optimized individually, the workload overall is not. Plans running together incur resource contention, resulting in sub-optimal performance. To address this, we introduce the idea of alternative-objective query optimization. Multiple query plans for the same query are generated, each optimized for an alternative resource usage. At runtime, the workload manager then can choose the plan for the query that works best for runtime conditions. This balances the system load, reducing contention, to increase overall workload throughput. © 2012 Springer-Verlag.\",\n \"Title: DDSN: Duplicate detection to reduce both storage and bandwidth consumption\\nYear: 2013\\n\\nAbstract: As highly centralized storage facilities are gaining popularity, duplicate detection becomes a critical problem. Traditional methods focus on reducing the storage space consumption; however, for network storage system with remote clients, the network overhead cannot be ignored, especially when the system is accessed over WAN. We propose a new duplicate detection method and implement a network file system prototype called DDSN based on this new method. It can reach the same performance in terms of storage space consumption as the state-of-the-art sliding blocking method. Meanwhile, our method overcomes its drawback that the whole file needs to be transmitted over the network, and therefore saves massive bandwidth for duplicate data. Experiments confirm the effectiveness of the proposed method.\",\n \"Title: Fast approximate computation of statistics on views\\nYear: 2006\\n\\nAbstract: Accurate estimation of the sizes of intermediate query results (cardinality estimation) is of critical importance to plan costing in query optimization. The common practice in current commercial database systems such as IBM DB2 Universal Database (DB2 UDB) is to derive the cardinality estimates from base-table statistics. However, this approach often suffers from simplifying yet unrealistic assumptions that have to be made about the underlying data (for example, different attributes are independently distributed).Ways for exploiting statistics on query expressions (or, statistics on views, or SITs) have been proposed to improve the accuracy of cardinality estimation. We propose a novel method for efficient computation of SITs for joins. In particular, we are concerned with statistics on join queries involving large fact tables and relatively small dimension tables. Rather than materializing the views, we make use of the frequency statistics that are available on the fact tables to obtain an approximate estimate of the statistics on various attributes in the join results. The dimension tables are generally much smaller than the fact table, and therefore we can afford to closely examine the dimension table, while at the same time avoid accessing the fact table. By closely examining the dimension table, we are able to capture the correlations between the attributes in the dimension table as well as the skew and domain range of the fact table join column values. This leads to reasonably accurate statistics on the join result. We prototyped this idea as a module on top of DB2 UDB, and our experience shows that employment of this technique results in a very significant speed-up in the computation of SITs, at the expense of only slight degradation in accuracy compared with the full-materialization method.\",\n \"Title: Indexing high-dimensional data for main-memory similarity search\\nYear: 2010\\n\\nAbstract: As RAM gets cheaper and larger, in-memory processing of data becomes increasingly affordable. In this paper, we propose a novel index structure, the CSR^+-tree, to support efficient high-dimensional similarity search in main memory. We introduce quantized bounding spheres (QBSs) that approximate bounding spheres (BSs) or data points. We analyze the respective pros and cons of both QBSs and the previously proposed quantized bounding rectangles (QBRs), and take the best of both worlds by carefully incorporating both of them into the CSR^+-tree. We further propose a novel distance computation scheme that eliminates the need for decompressing QBSs or QBRs, which results in significant cost savings. We present an extensive experimental evaluation and analysis of the CSR^+-tree, and compare its performance against that of other representative indexes in the literature. Our results show that the CSR^+-tree consistently outperforms other index structures.\",\n \"Title: Mining Online Reviews for Predicting Sales Performance: A Case Study in the Movie Domain\\nYear: 2012\\n\\nAbstract: Posting reviews online has become an increasingly popular way for people to express opinions and sentiments toward the products bought or services received. Analyzing the large volume of online reviews available would produce useful actionable knowledge that could be of economic values to vendors and other interested parties. In this paper, we conduct a case study in the movie domain, and tackle the problem of mining reviews for predicting product sales performance. Our analysis shows that both the sentiments expressed in the reviews and the quality of the reviews have a significant impact on the future sales performance of products in question. For the sentiment factor, we propose Sentiment PLSA (S-PLSA), in which a review is considered as a document generated by a number of hidden sentiment factors, in order to capture the complex nature of sentiments. Training an S-PLSA model enables us to obtain a succinct summary of the sentiment information embedded in the reviews. Based on S-PLSFA, we propose ARSA, an Autoregressive Sentiment-Aware model for sales prediction. We then seek to further improve the accuracy of prediction by considering the quality factor, with a focus on predicting the quality of a review in the absence of user-supplied indicators, and present ARSQA, an Autoregressive Sentiment and Quality Aware model, to utilize sentiments and quality for predicting product sales performance. Extensive experiments conducted on a large movie data set confirm the effectiveness of the proposed approach.\",\n \"Title: An extension of cooperative fuzzy games\\nYear: 2010\\n\\nAbstract: In this paper, a generalized form of fuzzy game is proposed that can be seen as an extension of the cooperative fuzzy game. Players in the proposed fuzzy game do not need to know precise information about the payoff value or to form a crisp coalition. Based on the Hukuhara difference, a game with a fuzzy characteristic function is studied, and the explicit form of a Shapley function is shown. Furthermore, we introduce and investigate a new class of fuzzy game with fuzzy coalitions and a fuzzy characteristic function. Based on the Hukuhara difference and the Choquet integral, we give the explicit form of the Shapley value for the new class of fuzzy game. It has been seen that most of the properties of a crisp game hold well in the proposed fuzzy game. A practical application of the proposed model in joint production problem is also provided.\",\n \"Title: Sentence-Level Sentiment Analysis in the Presence of Modalities\\nYear: 2014\\n\\nAbstract: This paper studies sentiment analysis of sentences with modality. The aim is to determine whether opinions expressed in sentences with modality are positive, negative or neutral. Modality is commonly used in text. In a typical corpus, there are around 18% of sentences with modality. Due to modality's special characteristics, the sentiment it bears may be hard to determine. For example, in the sentence, this cellphone would be perfect if it has a bigger screen, the speaker is negative about this phone although there is a typically positive opinion word \\\\\\\"perfect\\\\\\\" in this sentence. This paper first presents a linguistic analysis of modality, and then identifies some features to train a support vector machine classifier to determine the sentiment orientation in such sentences. Experimental results on sentences with modality extracted from the reviews of four different products are given to illustrate the effectiveness of the proposed method.\",\n \"Title: An Adaptive Model for Probabilistic Sentiment Analysis\\nYear: 2010\\n\\nAbstract: Online reviews, which are getting increasingly prevalent with the rapid growth of Web 2.0, have been shown to be second only to \\\"word-of-mouth\\\" in terms of influencing purchase decisions. It is therefore imperative to analyze them and distill useful knowledge that could be of economic values to vendors and other interested parties. Previous studies have confirmed that the sentiments expressed in the online reviews are strongly correlated with the sales performance of products. In particular, a model called ARSA has been proposed for predicting sales performance using a model called S-PLSA. In this paper, we build upon that work, and present an adaptive sentiment analysis model called S-PLSA+, which not only can capture the hidden sentiment factors in the reviews, but has the capability to be incrementally updated as more data become available. We show how the proposed S-PLSA+ model can be applied to sales performance prediction using the ARSA model. A case study is conducted in the movie domain, and results from preliminary experiments confirm the effectiveness of the proposed model.\",\n \"Title: Reasoning About Approximate Match Query Results\\nYear: 2006\\n\\nAbstract: Join techniques deploying approximate match predicates are fundamental data cleaning operations. A variety of predicates have been utilized to quantify approximate match in such operations and some have been embedded in a declarative data cleaning framework. These techniques return pairs of tuples from both relations, tagged with a score, signifying the degree of similarity between the tuples in the pair according to the specific approximate match predicate. In this paper, we consider the problem of estimating various parameters on the output of declarative approximate join algorithms for planning purposes. Such algorithms are highly time consuming, so precise knowledge of the result size as well as its score distribution is a pressing concern. This knowledge aids decisions as to which operations are more promising for identifying highly similar tuples, which is a key operation for data cleaning. We propose solution strategies that fully comply with a declarative framework and analytically reason about the quality of the estimates we obtain as well as the performance of our strategies. We present the results of a detailed performance evaluation of all strategies proposed. Our experimental results validate our analytical expectations and shed additional light on the quality and performance of our estimation framework. Our study offers a set of simple, fully declarative techniques for this problem, which can be readily deployed in data cleaning systems.\",\n \"Title: S-PLASA+: adaptive sentiment analysis with application to sales performance prediction\\nYear: 2010\\n\\nAbstract: Analyzing the large volume of online reviews would produce useful knowledge that could be of economic values to vendors and other interested parties. In particular, the sentiments expressed in the online reviews have been shown to be strongly correlated with the sales performance of products. In this paper, we present an adaptive sentiment analysis model called S-PLSA+, which aims to capture the hidden sentiment factors in the reviews with the capability to be incrementally updated as more data become available. We show how S-PLSA+ can be applied to sales performance prediction using an ARSA model developed in previous literature. A case study is conducted in the movie domain, and results from preliminary experiments confirm the effectiveness of the proposed model.\",\n \"Title: Towards estimating the number of distinct value combinations for a set of attributes\\nYear: 2005\\n\\nAbstract: Accurately and efficiently estimating the number of distinct values for some attribute(s) or sets of attributes in a data set is of critical importance to many database operations, such as query optimization and approximation query answering. Previous work has focused on the estimation of the number of distinct values for a single attribute and most existing work adopts a data sampling approach. This paper addresses the equally important issue of estimating the number of distinct value combinations for multiple attributes which we call COLSCARD (for COLumn Set CARDinality). It also takes a different approach that uses existing statistical information (e.g., histograms) available on the individual attributes to assist estimation. We start with cases where exact frequency information on individual attributes is available, and present a pair of lower and upper bounds on COLSCARD that are consistent with the available information, as well as an estimator of COLSCARD based on probability. We then proceed to study the case where only partial information (in the form of histograms) is available on individual attributes, and show how the proposed estimator can be adapted to this case. We consider two types of widely used histograms and show how they can be constructed in order to obtain optimal approximation. An experimental evaluation of the proposed estimation method on synthetic as well as two real data sets is provided.\",\n \"Title: HASE: a hybrid approach to selectivity estimation for conjunctive predicates\\nYear: 2006\\n\\nAbstract: Current methods for selectivity estimation fall into two broad categories, synopsis-based and sampling-based. Synopsis-based methods, such as histograms, incur minimal overhead at query optimization time and thus are widely used in commercial database systems. Sampling-based methods are more suited for ad-hoc queries, but often involve high I/O cost because of random access to the underlying data. Though both methods serve the same purpose of selectivity estimation, their interaction in the case of selectivity estimation for conjuncts of predicates on multiple attributes is largely unexplored. Our work aims at taking the best of both worlds, by making consistent use of synopses and sample information when they are both present. To achieve this goal, we propose HASE, a novel estimation scheme based on a powerful mechanism called generalized raking. We formalize selectivity estimation in the presence of single attribute synopses and sample information as a constrained optimization problem. By solving this problem, we obtain a new set of weights associated with the sampled tuples, which has the nice property of reproducing the known selectivities when applied to individual predicates. We discuss different variants of the optimization problem and provide algorithms for solving it. We also provide asymptotic error bounds on the estimate. Extensive experiments are performed on both synthetic and real data, and the results show that HASE significantly outperforms both synopsis-based and sampling-based methods.\",\n \"Title: CSR+-tree: Cache-conscious Indexing for High-dimensional Similarity Search\\nYear: 2007\\n\\nAbstract: In this paper, we propose a novel index structure, the CSR+-tree, to support efficient high-dimensional similarity search in main memory. We introduce quantized bounding spheres (QBSs) that approximate bounding spheres (BSs) or data points. We analyze the respective pros and cons of both QBSs and the previously proposed quantized bounding rectangles (QBRs), and take the best of both worlds by carefully incorporating both of them into the CSR+-tree. We further propose a novel distance computation scheme that eliminates the need for decompressing QBSs or QBRs, which results in significant cost savings. We present an extensive experimental evaluation and analysis of the CSR+-tree, and compare its performance against that of other representative indexes in the literature. Our results show that the CSR+-tree consistently outperforms other index structures.\",\n \"Title: Reasoning about similarity queries in text retrieval tasks\\nYear: 2008\\n\\nAbstract: In many text retrieval tasks, it is highly desirable to obtain a \\\"similarity profile\\\" of the document collection for a given query. We propose sampling-based techniques to address this need, using calibration techniques to improve the accuracy. Experimental results confirm the effectiveness of the proposed approaches.\",\n \"Title: Riding the tide of sentiment change: sentiment analysis with evolving online reviews\\nYear: 2013\\n\\nAbstract: The last decade has seen a rapid growth in the volume of online reviews. A great deal of research has been done in the area of opinion mining, aiming at analyzing the sentiments expressed in those reviews towards products and services. Most of the such work focuses on mining opinions from a collection of reviews posted during a particular period, and does not consider the change in sentiments when the collection of reviews evolve over time. In this paper, we fill in this gap, and study the problem of developing adaptive sentiment analysis models for online reviews. Given the success of latent semantic modeling techniques, we propose two adaptive methods to capture the evolving sentiments. As a case study, we also investigate the possibility of using the extracted adaptive patterns for sales prediction. Our proposal is evaluated on an IMDB dataset consisting of reviews of selected movies and their box office revenues. Experimental results show that the adaptive methods can capture sentiment changes arising from newly available reviews, which helps greatly improve the prediction accuracy.\",\n \"Title: Sharpe Ratio-Oriented Active Trading: A Learning Approach\\nYear: 2002\\n\\nAbstract: Portfolio offers an effective way for managing investment risk through diversification. The key issue in portfolio management is how to determine the weight (portion) of each asset in the portfolio, so as to achieve high profit with low risk over a certain period of trading. We propose a learning-based trading strategy for portfolio management, which aims at maximizing the Sharpe Ratio by actively reallocating wealth among assets. The trading decision is formulated as a non-linear function of the latest realized asset returns, and the function can be approximated by a neural-network. Two methods based on supervised learning to train the network are proposed. Experiments show that the proposed trading strategy outperforms the static Sharpe Ratio trading method.\",\n \"Title: Pollux: towards scalable distributed real-time search on microblogs\\nYear: 2013\\n\\nAbstract: The last few years have witnessed a meteoric rise of microblogging platforms, such as Twitter and Tumblr. The sheer volume of the microblog data and its highly dynamic nature present unique technical challenges for the platforms that provide search services. In particular, the search service must provide real-time response to queries, and continuously update the results as new microblogs are posted. Conventional approaches either cannot keep up with the high update rate, or cannot scale well to handle the large volume of data. We propose Pollux, a system that provides distributed real-time indexing and search service on microblogs. It adopts the distributed stream processing paradigm advocated by the recently developed platforms that are designed for real-time processing of large volume of data, such as Apache S4 and Twitter Storm. Although those open-source platforms have found successful applications in production environments, they lack some critical features required for real-time search. In particular: (1) they only implement partial fault tolerance, and do not provide lossless recovery in the event of a node failure, and (2) they do not have a facility for storing global data, which is necessary in efficiently ranking search results. Addressing those problems, Pollux extends current platforms in two important ways. First, we propose a failover strategy that can ensure high system availability and no data/state loss in the event of a node failure. Second, Pollux adds a global storage facility that supports convenient, efficient, and reliable data storage for shared data. We describe how to apply Pollux to the task of real-time search. We implement Pollux based on Apache S4, and show through extensive experiments on a Twitter dataset that the proposed solutions are effective, and Pollux can achieve excellent scalability.\",\n \"Title: Keyword query cleaning with query logs\\nYear: 2011\\n\\nAbstract: Keyword queries over databases are often dirty with some irrelevant or incorrect words, which has a negative impact on the efficiency and accuracy of keyword query processing. In addition, the keywords in a given query often form natural segments. For example, the query \\\"Tom Hanks Green Mile\\\" can be considered as consisting of two segments, \\\"Tom Hanks\\\" and \\\"Green Mile\\\".The goal of keyword query cleaning is to identify the optimal segmentation of the query, with semantic linkage and spelling corrections also considered.Query cleaning not only helps obtaining queries of higher quality, but also improves the efficiency of query processing by reducing the search space. The seminal work along this direction by Pu and Yu does not consider the role of query logs in performing query cleaning. Query logs contain user-issued queries together with the segmentations chosen by the user, and thus convey important information that reflects user preferences. In this paper, we explore the use of query logs to improve the quality of keyword query cleaning. We propose two methods to adapt the scoring functions of segmentations to account for information gathered from the logs. The effectiveness of our approach are verified with extensive experiments conducted on real data sets.\",\n \"Title: Hashed samples: selectivity estimators for set similarity selection queries\\nYear: 2008\\n\\nAbstract: We study selectivity estimation techniques for set similarity queries. A wide variety of similarity measures for sets have been proposed in the past. In this work we concentrate on the class of weighted similarity measures (e.g., TF/IDF and BM25 cosine similarity and variants) and design selectivity estimators based on a priori constructed samples. First, we study the pitfalls associated with straightforward applications of random sampling, and argue that care needs to be taken in how the samples are constructed; uniform random sampling yields very low accuracy, while query sensitive realtime sampling is more expensive than exact solutions (both in CPU and I/O cost). We show how to build robust samples a priori, based on existing synopses for distinct value estimation. We prove the accuracy of our technique theoretically, and verify its performance experimentally. Our algorithm is orders of magnitude faster than exact solutions and has very small space overhead.\",\n \"Title: FRISK: Keyword Query Cleaning and Processing in Action\\nYear: 2009\\n\\nAbstract: Keyword search provides a simple yet effective way for the users to query and explore the underlying documents. In the recent years, there have been a great deal of research and development activities on extending keyword search capabilities to handle relational data, the dominant form in which business data are stored. Algorithms and prototype systems, such as Discover, DBXplorer, BANKS, and SPARK, have been developed to support retrieving relevant information from relational databases using keyword queries.\",\n \"Title: ARSA: a sentiment-aware model for predicting sales performance using blogs\\nYear: 2007\\n\\nAbstract: Due to its high popularity, Weblogs (or blogs in short) present a wealth of information that can be very helpful in assessing the general public's sentiments and opinions. In this paper, we study the problem of mining sentiment information from blogs and investigate ways to use such information for predicting product sales performance. Based on an analysis of the complex nature of sentiments, we propose Sentiment PLSA (S-PLSA), in which a blog entry is viewed as a document generated by a number of hidden sentiment factors. Training an S-PLSA model on the blog data enables us to obtain a succinct summary of the sentiment information embedded in the blogs. We then present ARSA, an autoregressive sentiment-aware model, to utilize the sentiment information captured by S-PLSA for predicting product sales performance. Extensive experiments were conducted on a movie data set. We compare ARSA with alternative models that do not take into account the sentiment information, as well as a model with a different feature selection method. Experiments confirm the effectiveness and superiority of the proposed approach.\",\n \"Title: Collaborative Filtering with Aspect-Based Opinion Mining: A Tensor Factorization Approach\\nYear: 2012\\n\\nAbstract: Collaborative filtering (CF) aims to produce user specific recommendations based on other users' ratings of items. Most existing CF methods rely only on users' overall ratings of items, ignoring the variety of opinions users may have towards different aspects of the items. Using the movie domain as a case study, we propose a framework that is able to capture users' opinions on different aspects from the textual reviews, and use that information to improve the effectiveness of CF. This framework has two components, an opinion mining component and a rating inference component. The former extracts and summarizes the opinions on multiple aspects from the reviews, generating ratings on the various aspects. The latter component, on the other hand, infers the overall ratings of items based on the aspect ratings, which forms the basis for item recommendation. Our core contribution is in the proposal of a tensor factorization approach for the rating inference. Operating on the tensor composed of the overall and aspect ratings, this approach is able to capture the intrinsic relationships between users, items, and aspects, and provide accurate predictions on unknown ratings. Experiments on a movie dataset show that our proposal significantly improves the prediction accuracy compared with two baseline methods.\",\n \"Title: Query segmentation using conditional random fields\\nYear: 2009\\n\\nAbstract: A growing mount of available text data are being stored in relational databases, giving rise to an increasing need for the RDBMSs to support effective text retrieval. In this paper, we address the problem of keyword query segmentation, i.e., how to group nearby keywords in a query into segments. This operation can greatly benefit both the quality and the efficiency of the subsequent search operations. Compared with previous work, the proposed approach is based on Conditional Random Fields (CRF), and provides a principled statistical model that can be learned from query logs and easily adapt to user preferences. Extensive experiments on two real datasets confirm the effectiveness the efficiency of the proposed approach.\",\n \"Title: HelpMeter: A Nonlinear Model for Predicting the Helpfulness of Online Reviews\\nYear: 2008\\n\\nAbstract: With the flourish of the Internet, online review mining has attracted a lot of attention from the research community. However, compared to various well-studied sentiment analysis and opinion summarization problems, less effort has been made to analyze the quality of online reviews. The objective of this paper is to fill in this gap by automatically evaluating the \\\"helpfulness\\\" of reviews and consequently developing novel models to identify the most helpful reviews for a particular product. In particular, based on a thorough analysis of various factors that may affect the review quality, we propose HelpMeter, a nonlinear regression model for helpfulness prediction. Some preliminary experiments were conducted on a movie review data set, and the performance results confirm the superiority of the proposed method.\",\n \"Title: Efficient Top-k Keyword Search Over Multidimensional Databases\\nYear: 2013\\n\\nAbstract: Keyword search over databases has recently received significant attention. Many solutions and prototypes have been developed. However, due to large memory consumption requirements and unpredictable running time, most of them cannot be applied directly to the situations where memory is limited and quick response is required, such as when performing keyword search over multidimensional databases in mobile devices as part of the OLAP functionalities. In this paper, the authors attack the keyword search problem from a new perspective, and propose a cascading top-k keyword search algorithm, which generates supernodes by a branch and bound method in each step of search instead of computing the Steiner trees as done in many existing approaches. This new algorithm consumes less memory and significantly reduces the response time. Experiments show that the method can achieve high search efficiency compared with the state-of-the-art approaches.\",\n \"Title: Existence of an elliptic system involving Pucci operator\\nYear: 2008\\n\\nAbstract: We study the existence of solutions for the nonlinear elliptic system {−Mλ,Λ+(D2u)=f1(x,u)+h1(u,v)in Ω,−Mλ,Λ+(D2v)=f2(x,v)+h2(u,v)in Ω,u>0,v>0in Ω,u=v=0on ∂Ω, where Ω is a bounded domain, f1 is superlinear and f2 is sublinear at zero and infinity, h1 and h2 are perturbation terms. We will show that the system has at least two semi-trivial solutions (u,0), (0,v) and a nontrivial solution (u∗,v∗).\",\n \"Title: Cascading top-k keyword search over relational databases\\nYear: 2011\\n\\nAbstract: Keyword search over relational databases has recently received significant attention. Many solutions and prototypes have been developed. However, due to large memory consumption requirements and unpredictable running time, most of them cannot be applied directly to situations where memory is limited and quick response is required, such as when performing keyword search over databases in mobile devices as part of the OLAP funtionalities. In this paper, we attack the keyword search problem from a new perspective, and propose a cascading top-k keyword search algorithm, which generates supernodes in each step of search instead of computing the Steiner trees as done in many existing approaches. This new algorithm consumes less memory and significantly reduces the response time. Experiments show that the method can achieve high search efficiency compared with the state-of-the-art approaches.\",\n \"Title: Combining integrated sampling with SVM ensembles for learning from imbalanced datasets\\nYear: 2011\\n\\nAbstract: Learning from imbalanced datasets is difficult. The insufficient information that is associated with the minority class impedes making a clear understanding of the inherent structure of the dataset. Most existing classification methods tend not to perform well on minority class examples when the dataset is extremely imbalanced, because they aim to optimize the overall accuracy without considering the relative distribution of each class. In this paper, we study the performance of SVMs, which have gained great success in many real applications, in the imbalanced data context. Through empirical analysis, we show that SVMs may suffer from biased decision boundaries, and that their prediction performance drops dramatically when the data is highly skewed. We propose to combine an integrated sampling technique, which incorporates both over-sampling and under-sampling, with an ensemble of SVMs to improve the prediction performance. Extensive experiments show that our method outperforms individual SVMs as well as several other state-of-the-art classifiers.\",\n \"Title: Modeling and Predicting the Helpfulness of Online Reviews\\nYear: 2008\\n\\nAbstract: Online reviews provide a valuable resource for potential customers to make purchase decisions. However, the sheer volume of available reviews as well as the large variations in the review quality present a big impediment to the effective use of the reviews, as the most helpful reviews may be buried in the large amount of low quality reviews. The goal of this paper is to develop models and algorithms for predicting the helpfulness of reviews, which provides the basis for discovering the most helpful reviews for given products. We first show that the helpfulness of a review depends on three important factors: the reviewerpsilas expertise, the writing style of the review, and the timeliness of the review. Based on the analysis of those factors, we present a nonlinear regression model for helpfulness prediction. Our empirical study on the IMDB movie reviews dataset demonstrates that the proposed approach is highly effective.\",\n \"Title: CI-Rank: Ranking Keyword Search Results Based on Collective Importance\\nYear: 2012\\n\\nAbstract: Keyword search over databases, popularized by keyword search in WWW, allows ordinary users to access database information without the knowledge of structured query languages and database schemas. Most of the previous studies in this area use IR-style ranking, which fail to consider the importance of the query answers. In this paper, we propose CI-RANK, a new approach for keyword search in databases, which considers the importance of individual nodes in a query answer and the cohesiveness of the result structure in a balanced way. CI-RANK is built upon a carefully designed model call Random Walk with Message Passing that helps capture the relationships between different nodes in the query answer. We develop a branch and bound algorithm to support the efficient generation of top-k query answers. Indexing methods are also introduced to further speed up the run-time processing of queries. Extensive experiments conducted on two real data sets with a real user query log confirm the effectiveness and efficiency of CI-RANK.\",\n \"Title: Traffic Session Identification Based on Statistical Language Model\\nYear: 2013\\n\\nAbstract: Session identification has attracted a lot of attention as it can play an important role in discovering useful patterns. A traffic session is a sequence of camera locations orderly passed by a vehicle to achieve a certain task. Based on the observations that both navigation regularity and temporal factor are crucial in determining the session boundaries, we propose an improved statistical language model which takes both factors into consideration in this paper. Extensive experiments are conducted on a real traffic dataset to testify the effectiveness of our proposal, and the result demonstrates its effectiveness compared to other alternative methods including the timeout method and the classic language model.\",\n \"Title: A quality-aware model for sales prediction using reviews\\nYear: 2010\\n\\nAbstract: Writing and publishing reviews online has become an increasingly popular way for people to express opinions and sentiments. Analyzing the large volume of online reviews available can produce useful knowledge that are of interest to vendors and other parties. Prior studies in the literature have shown that online reviews have a significant correlation with the sales of products, and therefore mining the reviews could help predict the sales performance of relevant products. However, those studies fail to consider one important factor that may significantly affect the accuracy of the prediction, i.e., the quality of the reviews. In this paper, we propose a regression model that explicitly takes into account the quality factor, and discusses how this quality information can be predicted when it is not readily available. Experimental results on a movie review dataset confirm the effectiveness of the proposed model.\",\n \"Title: Scalable Distributed Processing of K Nearest Neighbor Queries over Moving Objects\\nYear: 2015\\n\\nAbstract: Central to many applications involving moving objects is the task of processing k-nearest neighbor (k-NN) queries. Most of the existing approaches to this problem are designed for the centralized setting where query processing takes place on a single server; it is difficult, if not impossible, for them to scale to a distributed setting to handle the vast volume of data and concurrent queries that are increasingly common in those applications. To address this problem, we propose a suite of solutions that can support scalable distributed processing of k-NN queries. We first present a new index structure called Dynamic Strip Index (DSI), which can better adapt to different data distributions than exiting grid indexes. Moreover, it can be naturally distributed across the cluster, therefore lending itself well to distributed processing. We further propose a distributed k-NN search (DKNN) algorithm based on DSI. DKNN avoids having an uncertain number of potentially expensive iterations, and is thus more efficient and more predictable than existing approaches. DSI and DKNN are implemented on Apache S4, an open-source platform for distributed stream processing. We perform extensive experiments to study the characteristics of DSI and DKNN, and compare them with three baseline methods. Experimental results show that our proposal scales well and significantly outperforms the alternative methods.\",\n \"Title: Weighted aspect-based collaborative filtering\\nYear: 2014\\n\\nAbstract: Existing work on collaborative filtering (CF) is often based on the overall ratings the items have received. However, in many cases, understanding how a user rates each aspect of an item may reveal more detailed information about her preferences and thus may lead to more effective CF. Prior work has studied extracting/quantizing sentiments on different aspects from the reviews, based on which the unknown overall ratings are inferred. However, in that work, all the aspects are treated equally; while in reality, different users tend to place emphases on difference aspects when reaching the overall rating. For example, users may give a high rating to a movie just for its plot despite its mediocre performances. This emphasis on aspects varies for different users and different items. In this paper, we propose a method that uses tensor factorization to automatically infer the weights of different aspects in forming the overall rating. The main idea is to learn, through constrained optimization, a compact representation of a weight tensor indexed by three dimensions for user, item, and aspect, respectively. Overall ratings can then be predicted using the obtained weights. Experiments on a movie dataset show that our method compares favorably with three baseline methods.\",\n \"Title: Continuous KNN Join Processing for Real-Time Recommendation\\nYear: 2014\\n\\nAbstract: The explosive growth of user-generated contents in social networking websites necessitates the recommendation functionality that can push to the user the content that he/she is most likely to be interested in. Such recommendation should happen in real-time as new contents become available, because \\\"freshness\\\" is an important consideration in people's content-consumption behavior. Representing users and contents as feature vectors in a high-dimensional space, we can essentially cast the problem of real-time recommendations as the problem of computing the list of k nearest neighbors of each user, which we call kNN join. Given the vast volume of contents and users, the biggest challenge is how to continuously update the kNN join results as new contents arrive. Existing methods for incremental kNN join on data streams suffer from the \\\"curse of dimensionality\\\" and high in-memory search cost. In this paper, we present a solution that first identifies the users whose kNN's might be affected by the newly arrived content, and then update their kNN's respectively. We propose a new index structure named HDR-tree in order to support the efficient search of affected users. HDR-tree performs dimensionality reduction through clustering and principle component analysis (PCA) in order to improve the search effectiveness. To further reduce response time, we propose a variant of HDR-tree, called HDR-tree, that supports more efficient but approximate solutions. The results of extensive experiments show that our methods significantly outperform baseline methods.\",\n \"Title: MeanKS: meaningful keyword search in relational databases with complex schema\\nYear: 2014\\n\\nAbstract: Keyword search in relational databases was introduced in the last decade to assist users who are not familiar with a query language, the schema of the database, or the content of the data. An answer is a join tree of tuples that contains the query keywords. When searching a database with a complex schema, there are potentially many answers to the query. Therefore, ranking answers based on their relevance is crucial in this context. Prior work has addressed relevance based on the size of the answer or the IR scores of the tuples. However, this is not sufficient when searching a complex schema. We demonstrate MeanKS, a new system for meaningful keyword search over relational databases. The system first captures the user's interest by determining the roles of the keywords. Then, it uses schema-based ranking to rank join trees that cover the keyword roles. This uses the relevance of relations and foreign-key relationships in the schema over the information content of the database. In the demonstration, attendees can execute queries against the TPC-E warehouse and compare the proposed measures against a gold standard derived from a real workload over TPC-E to test the effectiveness of our methods.\",\n \"Title: Signaling adverse drug reactions with novel feature-based similarity model\\nYear: 2014\\n\\nAbstract: Adverse drug reactions (ADRs) are a main cause of hospitalization and deaths worldwide. These unanticipated episodes are generally infrequent, but almost all existing ADR signaling techniques are designed to use dataset extracted from spontaneous reporting systems or employed a predefined type of information (e.g., drugs), which suffer from failures to detect unexpected and latent ADRs. In this paper, we propose a novel Feature-based Similarity model (FS) to detect the potential ADRs for medical cases using the electronic patient dataset. FS is tested on the real patient data retrieved from the US Food Drug Administration that includes 54,070 patients detail information and 9,567 ADRs records. Our model ranked all ADRs for the given medical case that combined the information of drugs, medical conditions, and patient profiles and can be applied in therapy decision support systems and unexpected ADR warning systems. The experimental results show that FS outperforms comparing methods. This paper clearly illustrates the great potential along the new direction of ADR signal generate from health care administrative database.\",\n \"Title: Ranking Keyword Search Results with Query Logs\\nYear: 2014\\n\\nAbstract: Keyword search provides a uniform way of accessing the vast volume of structured and unstructured data present in many enterprises. Existing research on improving the effectiveness of the keyword search has largely focused on result ranking mechanisms, with little consideration given to user feedback. We are working towards developing a new approach to ranking the results of keyword search over structured data (stored in databases) using feedback information in the form of query logs. Our work is based on the schema-graph-based approach to keyword search, which consists of a candidate network (CN) generation phase and a CN evaluation phase. Our proposal is to extract the frequent patterns from the query log of a user (or a user group) and use them in ranking the CNs generated by the first phase. We present a concise description of our approach and lay out our plan for the next stage of research. Preliminary experiment results on a real dataset are also included.\",\n \"Title: GrandLand Traffic Data Processing Platform\\nYear: 2014\\n\\nAbstract: Recent years have seen an increasing number of traffic surveillance cameras deployed on the main roads and intersections of metropolitan areas. For large and ediumsized cities, these cameras generate an enormous amount of data. Existing solutions based relational database systems cannot effectively manage and process such large volume of data, nor can they provide support for efficient and scalable support for either analytical tasks or tasks requiring response in real-time. To address these challenges, we have developed the GrandLand Traffic Data Processing Platform (GLPlatform) to provide distributed, scalable processing of traffic surveillance data.\",\n \"Title: Towards Efficient KNN Joins on Data Streams\\nYear: 2014\\n\\nAbstract: We study the problem of efficient processing of kNN joins over high-dimensional data streams, which is an operation required by many big data applications. Specifically, we are concerned with the continuous evaluation of a set of k nearest neighbor queries Q on streams of high-dimensional items at consecutive snapshots of those streams. While one possible solution is to evaluate the kNN joins starting from scratch at each snapshot, it is too expensive for large volumes of data we encounter in big data applications. We consider the data stream on a time window and maintain the join results for Q at every snapshot in main memory. Our approach to this problem is to build indexes on Q, and only update the results of the queries affected by the changes in the streams at each snapshot. We propose a main-memory structure called the High-dimensional R-tree (HDR-tree) to index the queries, which is efficient in finding affected queries with reasonable maintenance cost. HDR-tree takes advantage of the benefit of clustering and the principle component analysis (PCA) technique. Preliminary experimental results show that our index structures significantly outperform baseline methods.\",\n \"Title: Monitoring k-Nearest Neighbor Queries over Moving Objects\\nYear: 2005\\n\\nAbstract: Many location-based applications require constant monitoring of k-nearest neighbor (k-NN) queries over moving objects within a geographic area. Existing approaches to this problem have focused on predictive queries, and relied on the assumption that the trajectories of the objects are fully predictable at query processing time. We relax this assumption, and propose two efficient and scalable algorithms using grid indices. One is based on indexing objects, and the other on queries. For each approach, a cost model is developed, and a detailed analysis along with the respective applicability are presented. The Object-Indexing approach is further extended to multi-levels to handle skewed data. We show by experiments that our grid-based algorithms significantly outperform R-tree-based solutions. Extensive experiments are also carried out to study the properties and evaluate the performance of the proposed approaches under a variety of settings.\",\n \"Title: Efficient Duplication Free and Minimal Keyword Search in Graphs\\nYear: 2014\\n\\nAbstract: Keyword search over a graph searches for a subgraph that contains a set of query keywords. A problem with most existing keyword search methods is that they may produce duplicate answers that contain the same set of content nodes (i.e., nodes containing a query keyword) although these nodes may be connected differently in different answers. Thus, users may be presented with many similar answers with trivial differences. In addition, some of the nodes in an answer may contain query keywords that are all covered by other nodes in the answer. Removing these nodes does not change the coverage of the answer but can make the answer more compact. The answers in which each content node contains at least one unique query keyword are called minimal answers in this paper. We define the problem of finding duplication-free and minimal answers, and propose algorithms for finding such answers efficiently. Extensive performance studies using two large real data sets confirm the efficiency and effectiveness of the proposed methods.\",\n \"Title: Mining moving patterns for predicting next location\\nYear: 2015\\n\\nAbstract: Next location prediction has been an essential task for many location based applications such as targeted advertising. In this paper, we present three basic models to tackle the problem of predicting next locations: the Global Markov Model that uses all available trajectories to discover global behaviors, the Personal Markov Model that focuses on mining the individual patterns of each moving object, and the Regional Markov Model that clusters the trajectories to mine the similar movement patterns. The three models are integrated with linear regression in different ways. We then seek to further improve the accuracy of prediction by considering the time factor, with a focus on clustering the trajectories in different time periods, and present three methods to train the time-aware models to mine periodic patterns. Therefore, our proposed models have the following advantages: (1) we consider both individual and collective movement patterns in making prediction, (2) we consider the similarity between different trajectories, (3) we consider the time factor and build models that are suited to different time periods. We have conducted extensive experiments on a real dataset, and the results demonstrate the superiority of our proposed models over existing methods. HighlightsWe propose three models (PMM, GMM and RMM) and combine them in different ways to obtain new models to predict the next location of a moving object.GMM uses all available trajectories to discover collective patterns; PMM models the individual patterns of each moving object using its own past trajectories; RMM clusters the trajectories to mine the movement patterns.Based on the observation that the movement patterns often change over time, we propose methods that can capture the relationships between the patterns in different time periods, and use this knowledge to build more refined models.To the best of our knowledge, the proposed models are the first ones that take a holistic approach and consider individual, collective movement patterns and the similarity between trajectories in making prediction.We conduct extensive experiments using a real dataset and the results demonstrate the effectiveness of the proposed models.\",\n \"Title: A smartphone app framework for segmented cancer care coordination.\\nYear: 2016\\n\\nAbstract: Complex cancer care requires careful coordination, but resource limitations result in lack of effective coordinated follow-up services. Recent advances in smartphones offer great opportunities for better segmentation of patient populations for cost-effective, targeted care coordination and monitoring or surveillance of cancer patients. This paper presents a framework of a smartphone app that provides such risk assessment and follow-up care monitoring services. This mHealth app framework includes three functional modules: a natural language processing module based on Bayesian model to extract relevant information from free text or medical reports; a cancer risk calculator that uses support vector machine classification to assess the medical risks of cancer patients based on the information extracted; and a health care monitor that provides timely care coordination to high risk cancer patients. The experimental results validate mHealth as a reliable medical risk assessment for post-surgical cancer patients and an effective health care monitoring service for cancer care coordination.\",\n \"Title: Data security and privacy management in healthcare applications and clinical data warehouse environment\\nYear: 2016\\n\\nAbstract: Health Information is considered the most sensitive information associated to an individual. Even though numerous suitable policies, guidelines, and compliance requirements are in place to safeguard health information, privacy and security breach remains key issues for electronic healthcare systems. In this paper we focus on these issues and propose a security and privacy model implemented in Methodist Environment for Translational and Outcomes Research (METEOR). METEOR was developed at Houston Methodist Hospital and consists of two components: the enterprise data warehouse (EDW) and a software intelligence and analytics (SIA) layer. This model indicates that patient privacy is best protected by implementing a systematic mix of technologies and best practices such as technical de-identification of data, restrictive data access, and security measures in the underlying technical platforms. Our results suggest that the proposed security model make data security compromise and unauthorized access of protected patient health information extremely improbable.\",\n \"Title: Meaningful keyword search in relational databases with large and complex schema\\nYear: 2015\\n\\nAbstract: Keyword search over relational databases offers an alternative way to SQL to query and explore databases that is effective for lay users who may not be well versed in SQL or the database schema. This becomes more pertinent for databases with large and complex schemas. An answer in this context is a join tree spanning tuples containing the query's keywords. As there are potentially many answers to the query, and the user is often only interested in seeing the top-k answers, how to rank the answers based on their relevance is of paramount importance. We focus on the relevance of join as the fundamental means to rank answers. We devise means to measure relevance of relations and foreign keys in the schema over the information content of the database. This can be done offline with no need for external models. We compare the proposed measures against a gold standard we derive from a real workload over TPC-E and evaluate the effectiveness of our methods. Finally, we test the performance of our measures against existing techniques to demonstrate a marked improvement, and perform a user study to establish naturalness of the ranking of the answers.\",\n \"Title: Predicting Next Locations with Object Clustering and Trajectory Clustering\\nYear: 2015\\n\\nAbstract: Next location prediction is of great importance for many location based applications. In many cases, understanding the similarity between objects and the similarity between trajectories may lead to more accurate predictions. In this paper, we propose two novel models exploiting these two types of similarities respectively. The first model, named object-clustered Markov model (object-MM), first clusters similar objects based on their spatial localities, and then builds variable-order Markov models with the trajectories of objects in the same cluster. The second model, named trajectory-clustered Markov model (tra-MM), considers the similarity between trajectories, and clusters the trajectories to form the training set used in building the Markov models. The two models are integrated to produce the final next location predictor (objectTra-MM). Experiments based on a real data set demonstrate significant increase in prediction accuracy of objectTra-MM over existing methods.\",\n \"Title: A Plane Moving Average Algorithm for Short-Term Traffic Flow Prediction.\\nYear: 2015\\n\\nAbstract: In this paper, a plane moving average algorithm is proposed for solving the urban road flow forecasting problem. This new approach assembles information from relevant traffic time series and has the following advantages: (1) it integrates both individual and similar flow patterns in making prediction, (2) the training data set does not need to be large, (3) it has more generalization capabilities in predicting unpredictable and much complex urban traffic flow than previously used methods. To assess the new model, we have performed extensive experiments on a real data set, and the results give evidence of its superiority over existing methods.\",\n \"Title: Sentiment analysis of sentences with modalities\\nYear: 2013\\n\\nAbstract: This paper is concerned with sentiment analysis of sentences with modality. Modality is a commonly occuring linguistic phenomenon. Due to its special characteristics, the sentiment borne by modality may be hard to determine by existing methods. We first present a linguistic analysis of modality, and then identify some valuable features to train a support vector machine classifier to determine the sentiment orientation of such sentences. We show experimental results on sentences with modality that are extracted from the reviews of four different products to illustrate the effectiveness of the proposed method.\",\n \"Title: Mining Object Similarity for Predicting Next Locations.\\nYear: 2016\\n\\nAbstract: Next location prediction is of great importance for many location-based applications. With the virtue of solid theoretical foundations, Markov-based approaches have gained success along this direction. In this paper, we seek to enhance the prediction performance by understanding the similarity between objects. In particular, we propose a novel method, called weighted Markov model (weighted-MM), which exploits both the sequence of just-passed locations and the object similarity in mining the mobility patterns. To this end, we first train a Markov model for each object with its own trajectory records, and then quantify the similarities between different objects from two aspects: spatial locality similarity and trajectory similarity. Finally, we incorporate the object similarity into the Markov model by considering the similarity as the weight of the probability of reaching each possible next location, and return the top-rankings as results. We have conducted extensive experiments on a real dataset, and the results demonstrate significant improvements in prediction accuracy over existing solutions.\",\n \"Title: VColor: A practical vertex-cut based approach for coloring large graphs\\nYear: 2016\\n\\nAbstract: Graph coloring is a fundamental NP-hard problem in graph theory. It has a wide range of real applications, such as Operations Research, Communication Network, Computational Biology and Compiler Optimization. Notable efforts have been spent on designing its approximation algorithms. Halldrsson proposed the algorithm (denoted as SampleIS) with the current best known approximation ratio. However, its time complexity is O(|G|3), where |G| is the number of vertices of a graph G. It is clear that SampleIS is not practical for large graphs. In this paper, we propose a practical vertex-cut based coloring technique (VColor) for coloring large graphs. First, we partition G into k connected components (CCs) of a small size s by removing a vertex-cut component (VCC). For each CC, we apply our novel coloring algorithm, based on maximal independent set enumeration. The approximation ratio and the time complexity for coloring the k CCs are log s + 1 and O(ks23s/3), respectively, whereas those of SampleIS are ks(log log ks)2/ log3 ks and O(k3s3). For the VCC, we simply apply SampleIS. To combine the colorings of the CCs and the VCC, we propose a maximum matching based algorithm. Second, in the context of a database of graphs, users may color many graphs. We propose an optimization technique, inspired by multi-query optimization, for coloring a set of graphs. We design a VP hierarchy (VPH) to represent the common subgraphs as the common CCs. Third, we propose techniques for determining the optimal values of the parameters of VColor. Our extensive experimental evaluation on real-world graphs confirms the efficiency and/or effectiveness of our proposed techniques. In particular, VColor is more than 500 times faster than SampleIS, and the number of colors used are comparable on real graphs Yeast and LS.\",\n \"Title: Privacy-Preserving Reachability Query Services for Massive Networks\\nYear: 2016\\n\\nAbstract: This paper studies privacy-preserving reachability query services under the paradigm of data outsourcing. Specically, graph data have been outsourced to a third-party service provider (SP), query clients submit their queries to the SP, and the SP returns the query answers to the clients. However, the SP may not always be trustworthy. Therefore, this paper investigates protecting the structural information of the graph data and the query answers from the SP. Existing techniques are either insecure or not scalable. This paper proposes a privacy-preserving labeling, called ppTopo. To our knowledge, ppTopo is the first work that can produce reachability index on massive networks and is secure against known plaintext attacks (KPA). Specifically, we propose an index construction algorithm for private reachability queries, by employing the idea of topological folding, recently proposed by Cheng et al. We propose a novel asymmetric scalar product encryption in modulo 3 (ASPE3). It allows us to encrypt the labels and transforms the queries into scalar products of encrypted labels. We perform an experimental study of the proposed technique on the datasets of SNAP networks. Compared with the existing methods, our results show that our technique is capable of producing the encrypted indexes at least 5 times faster for massive networks and the client's decryption time is 2-3 times smaller for most graphs. We also propose the heuristic optimization to reduce the size of index.\",\n \"Title: Collaborative filtering with weighted opinion aspects.\\nYear: 2016\\n\\nAbstract: Collaborative filtering (CF) aims to produce recommendations based on other users' ratings to an item. Most existing CF methods rely on the overall ratings an item has received. However, these ratings alone sometimes cannot provide sufficient information to understand users' behaviors. For example, a user giving a high rating may indicate that he loves the item as a whole; however, it is still likely that he dislikes some particular aspects at the same time. In addition, users tend to place different emphases on different aspects when reaching an overall rating. This emphasis on aspects may even vary from users to items, and has a significant impact on a user's final decision. To make a better understanding of a user' behavior and generate a more accurate recommendation, we propose a framework that incorporates both user opinions and preferences on different aspects. This framework is composed of three components, namely, an opinion mining component, an aspect weighting computing component, and a rating inference component. The first component exploits opinion mining techniques to extract and summarize opinions on multiple aspects from reviews, and generates ratings on various aspects. The second component applies a tensor factorization strategy to automatically infer weights of different aspects in reaching an overall rating. The last one infers the overall rating of an item based on both aspect ratings and weights. Experiments on two real datasets prove that our model performs better compared with the baseline methods.\",\n \"Title: Repair Singleton IDs on the Fly.\\nYear: 2016\\n\\nAbstract: Tracking moving entities at predefined locations plays an essential role in many surveillance related applications. Occasionally, the IDs of those entities are incorrectly recorded due to various reasons such as errors in recognition. Such errors need to be repaired on the fly as those IDs are often involved in some time-sensitive query processing or data analysis tasks. In this paper, we address a specific case where the errors result in singleton IDs, i.e., IDs that appear only once during a specific period of time and thus could be safely presumed to be erroneous. The repair of the IDs is based on constraints posed by the data itself (e.g., constraints posed by the road network). We present a tracking tree structure to index the candidate repairs for each singleton ID, which enables repairing of the IDs on the fly. We implement a distributed repair system on the Apache Storm platform. Experiments on both real and synthetic datasets demonstrate the effectiveness and efficiency of our singleton detection and repair approach.\",\n \"Title: Spica: A Path Bundling Model for Rational Route Recommendation.\\nYear: 2016\\n\\nAbstract: This paper presents Spica, a path bundling model for rational route recommendation leveraging the intelligence and experience of the past driving records. In this model, the traffic surveillance system is employed to probe the traffic rhythm of a city and vehicle traveling record’s intelligence is used to choose driving directions in the real world. We propose Joint Technique (JT) to build Time-Dependent Joint (TDJ) graph and model the dynamic traffic pattern so as to provide the rational fastest route to a given destination at a given starting time. Then we estimate the travel time in different time slots and based on TDJ graph, we propose Time-Dependent Heuristic Algorithm (TDHA) to compute the rational recommended routes. We build our model based on a real-world trajectory data set generated by totally 44,593,706 passage records in a period of a week, and evaluate the performance of our model by conducting extensive experiments. The recommended routes are effective and JT gives evidence of its rationality over previous ways.\",\n \"Title: KEIPD: Knowledge Extraction and Inference System for Personal Documents.\\nYear: 2016\\n\\nAbstract: Public personal documents on the Internet, such as resumes and personal homepages, may imply social relationships among people, which is of great value in various applications. This paper presents KEIPD, a system to extract and infer knowledge from personal documents. KEIPD employs a tree-similarity based approach to extract information from personal documents to obtain a relational network of entities. Then the inference of social relationships can be transformed into a link prediction problem. KEIPD implements some popular unsupervised predictors for link prediction and prune the candidate entity pairs based on the domain-dependent constraint.\",\n \"Title: Distributed Top-k Keyword Search over Very Large Databases with MapReduce\\nYear: 2016\\n\\nAbstract: In the last decade, keyword search over relational databases has been extensively studied because it promises to allow users lacking knowledge of structured query languages or unaware of the database schema to query the database in an intuitive way. The existing works about keyword search on databases proposed many approaches and have gain remarkable results. However, most of these approaches are designed for the centralized setting where keyword search is processed by only a single server. In reality, the scale of databases increases sharply and centralized methods hardly can handle keyword queries over these large databases. Moreover, processing keyword search over relational databases is a very time-consuming task, and the efficiency of the existing centralized approaches will degrade notably because the single server cannot provide enough computation power for the keyword search over very large databases. To address these challenges, we propose a distributed keyword search (DKS) approach with MapReduce and this approach can be well deployed on a cluster of servers to deal with keyword search over large databases in a parallel way.\",\n \"Title: CI-Rank: Collective importance ranking for keyword search in databases.\\nYear: 2017\\n\\nAbstract: Keyword search over databases, popularized by keyword search in WWW, allows ordinary users to access database information without the knowledge of structured query languages and database schemas. Most of the previous studies in this area use IR-style ranking, which fail to consider the importance of the query answers. In this paper, we propose CI-Rank, a new approach to keyword search in databases, which considers the importance of individual nodes in a query answer and the cohesiveness of the result structure in a balanced way. CI-Rank is built upon a carefully designed model called Random Walk with Message Passing that helps capture the relationships between different nodes in the query answer. This model lends itself well to adaptation to user preferences. We develop a branch and bound algorithm to support the efficient generation of top-k query answers. Indexing methods are also introduced to further speed up the run-time processing of queries. Extensive experiments conducted on two real data sets with a real user query log confirm the effectiveness and efficiency of CI-Rank.\",\n \"Title: Weighted Co-Training for Cross-Domain Image Sentiment Classification.\\nYear: 2017\\n\\nAbstract: Image sentiment classification, which aims to predict the polarities of sentiments conveyed by the images, has gained a lot of attention. Most existing methods address this problem by training a general classifier with certain visual features, ignoring the discrepancies across domains. In this paper, we propose a novel weighted co-training method for cross-domain image sentiment classification, which iteratively enlarges the labeled set by introducing new high-confidence classified samples to reduce the gap between the two domains. We train two sentiment classifiers with both the images and the corresponding textual comments separately, and set the similarity between the source domain and the target domain as the weight of a classifier. We perform extensive experiments on a real Flickr dataset to evaluate the proposed method, and the empirical study reveals that the weighted co-training method significantly outperforms some baseline solutions.\",\n \"Title: A Fuzzy Owen function on games with coalition structure and fuzzy coalitions.\\nYear: 2017\\n\\nAbstract: In this paper, a game with coalition structure and fuzzy coalitions is introduced, which can be regarded as an extension of the game with coalition structure. Firstly, an Owen function is defined. Then, the unique explicit form of the Owen function is given by extending the Owen value. Secondly, as an extension of Owen function, a fuzzy Owen function is proposed. In addition, an explicit form of the fuzzy Owen function is given by considering the fuzzy intermediate game with Owen extension form. Finally, an illustrate example is provided to illustrate the allocation method of gains.\",\n \"Title: Characteristics of Evapotranspiration of Urban Lawns in a Sub-Tropical Megacity and Its Measurement by the 'Three Temperature Model + Infrared Remote Sensing' Method.\\nYear: 2017\\n\\nAbstract: Evapotranspiration (ET) is one of the most important factors in urban water and energy regimes. Because of the extremely high spatial heterogeneity of urban area, accurately measuring ET using conventional methods remains a challenge due to their fetch requirements and low spatial resolution. The goals of this study were to investigate the characteristics of urban ET and its main influencing factors and subsequently to improve a fetch-free, high spatial resolution method for urban ET estimation. The Bowen ratio and the 'three-temperature model (3T model) + infrared remote sensing (RS)' methods were used for these purposes. The results of this study are listed in the following lines. (1) Urban ET is mainly affected by solar radiation and the effects of air humidity, wind velocity, and air temperature are very weak; (2) The average daily, monthly, and annual ETs of the urban lawn are 2.70, 60-100, and 990 mm, respectively, which are obvious compared with other landscapes; (3) The ratio of ET to precipitation is 0.65 in the wet season and 2.6 in the dry season, indicating that most of the precipitation is evaporated; (4) The fetch-free approach of '3T model + infrared RS' is verified to be an accurate method for measuring urban ET and it agrees well with the Bowen ratio method (R-2 is over 0.93 and the root mean square error is less than 0.04 mm h(-1)); (5) The spatial heterogeneity of urban ET can also be accurately estimated by the proposed approach. These results are helpful for improving the accuracy of ET estimation in urban areas and are useful for urban water and environmental planning and management.\",\n \"Title: The fuzzy bargaining set of cooperative game with fuzzy coalition.\\nYear: 2017\\n\\nAbstract: In this paper, the fuzzy bargaining set of cooperative game with fuzzy coalition is proposed, which can be regarded as the generalization of crisp bargaining set. The fuzzy bargaining set is based on the assumption that the total worth of a fuzzy coalition will be allocated to the players whose participation rate is larger than zero. Because fuzzy core had been proposed as a kind of solution for the fuzzy games, the relationship between fuzzy bargaining set and fuzzy core is also showed. Surprisingly, the relationship between fuzzy bargaining set and fuzzy core does coincide as in the classical case. The property of fuzzy bargaining set is also analyzed, such as the existence condition of counter-objection.\",\n \"Title: Lce: A Location Category Embedding Model For Predicting The Category Labels Of Pois\\nYear: 2017\\n\\nAbstract: The proliferation of location-based social networks, makes it possible to record human mobility using an array of points-of-interest (POIs). Exploring the semantic meanings of POIs can be of great importance to many urban computing applications, e.g., personalized route recommendation and user trajectory clustering. Nonetheless, such information is not always available in practice. This paper aims at predicting the category labels, which will provide a succinct summarization of POIs. In particular, we first propose a Location Category Embedding (LCE) model, which projects user POIs and their associated category labels into the same vector space, and then identify the POIs' most related category labels according to their similarities. To capture the influence that might affect users' moving behavior, LCE considers sequential pattern, personal preference, and temporal influence, and further models the connection between the POIs and the three factors. Experimental results on two real-world datasets prove the effectiveness of the proposed method.\",\n \"Title: Cooperative game with fuzzy coalition and payoff value in the generalized integral form.\\nYear: 2017\\n\\nAbstract: In this paper, a new class of games with fuzzy coalitions and fuzzy payoff value is proposed. This class of fuzzy games is based on the generalized integral form, which contains several kinds of other fuzzy games, such as fuzzy cooperative game with fuzzy payoff value, the multilinear extension game introduced by Owen, the game with proportional value proposed by Butnariu and the game with Choquet integral form given by Tsurumi et al. Also, the proposed fuzzy game is also further extension of the fuzzy game in Choquet integral form proposed by Yu et al., which is also is a kind of fuzzy games in the condition that coalition and fuzzy payoff value are both fuzzy information. The fuzzy Shapley value for this kind of fuzzy games is represented by Shapley value of corresponding fuzzy cooperative game with fuzzy payoff value. Based on Hukuhara-difference, we give the explicit Shapley value for the proposed fuzzy game. It has been seen that most of properties hold well in the proposed fuzzy game, which are processed by cooperation game with fuzzy payoff value, and fuzzy coalition game, respectively. Finally, a practical application of the proposed model is also provided.\",\n \"Title: A PSO-Powell Hybrid Method to Extract Fiber Orientations from ODF.\\nYear: 2018\\n\\nAbstract: High angular resolution diffusion imaging (HARDI) has opened up new perspectives for the delineation of crossing and branching fiber pathways by orientation distribution function (ODF). The fiber orientations contained in an imaging voxel are the key factor in tractography. To extract real fiber orientations from ODF, a hybrid method is proposed for computing the principal directions of ODF by combining the variation of Particle Swarm Optimization (PSO) algorithm with the modified Powell algorithm. This method is comprised of the global searching ability of PSO and the powerful local optimizing of Powell search. This combination can guarantee finding all the diffusion directions without applying sliding windows and improve the accuracy and efficiency. The proposed approach was evaluated on simulated crossing-fiber datasets, Tractometer, and in vivo datasets. The results show that this method could correctly identify fiber directions under a range of noise levels. This method was compared with the state-of-the-art methods, such as modified Powell, ball-stick model, and diffusion decomposition, showing that it outperformed them. As to the multimodal voxels where different fiber populations exist, the proposed approach allows us to improve the estimation accuracy of fiber orientations from ODF. It can play a significant role in the nerve fiber tracking.\",\n \"Title: A Perception-Driven Approach to Supervised Dimensionality Reduction for Visualization.\\nYear: 2018\\n\\nAbstract: Dimensionality reduction (DR) is a common strategy for visual analysis of labeled high-dimensional data. Low-dimensional representations of the data help, for instance, to explore the class separability and the spatial distribution of the data. Widely-used unsupervised DR methods like PCA do not aim to maximize the class separation, while supervised DR methods like LDA often assume certain spatial...\",\n \"Title: Model-based Clustering of Short Text Streams.\\nYear: 2018\\n\\nAbstract: Short text stream clustering has become an increasingly important problem due to the explosive growth of short text in diverse social medias. In this paper, we propose a model-based short text stream clustering algorithm (MStream) which can deal with the concept drift problem and sparsity problem naturally. The MStream algorithm can achieve state-of-the-art performance with only one pass of the stream, and can have even better performance when we allow multiple iterations of each batch. We further propose an improved algorithm of MStream with forgetting rules called MStreamF, which can efficiently delete outdated documents by deleting clusters of outdated batches. Our extensive experimental study shows that MStream and MStreamF can achieve better performance than three baselines on several real datasets.\",\n \"Title: A review of anisotropic conductivity models of brain white matter based on diffusion tensor imaging.\\nYear: 2018\\n\\nAbstract: The conductivity of brain tissues is not only essential for electromagnetic source estimation (ESI), but also a key reflector of the brain functional changes. Different from the other brain tissues, the conductivity of whiter matter (WM) is highly anisotropic and a tensor is needed to describe it. The traditional electrical property imaging methods, such as electrical impedance tomography (EIT) and magnetic resonance electrical impedance tomography (MREIT), usually fail to image the anisotropic conductivity tensor of WM with high spatial resolution. The diffusion tensor imaging (DTI) is a newly developed technique that can fulfill this purpose. This paper reviews the existing anisotropic conductivity models of WM based on the DTI and discusses their advantages and disadvantages, as well as identifies opportunities for future research on this subject. It is crucial to obtain the linear conversion coefficient between the eigenvalues of anisotropic conductivity tensor and diffusion tensor, since they share the same eigenvectors. We conclude that the electrochemical model is suitable for ESI analysis because the conversion coefficient can be directly obtained from the concentration of ions in extracellular liquid and that the volume fraction model is appropriate to study the influence of WM structural changes on electrical conductivity. Graphical abstract ᅟ.\",\n \"Title: Linear fuzzy game with coalition interaction and its coincident solutions.\\nYear: 2018\\n\\nAbstract: In this study, we consider the solution concepts for fuzzy coalition games (i.e., cooperative games with fuzzy coalition) under a certain participation level. In general, cooperative games with fuzzy coalition are based on the assumption that all the fuzzy coalition values for different fuzzy coalitions must be represented by the same formula, which may omit the coalition interaction under different participation ratios for players. Considering these conditions, we propose the coincident fuzziness form for games with fuzzy coalition, which are represented by a mapping from the characteristic function of the crisp game to that of the fuzzy coalition game. The proposed fuzzy coalition games admit the differences in coalition interactions for different fuzzy coalitions, where the coalition interactions are represented by the fuzzy coalition values in different ways (or formulas). For a fixed fuzzy coalition, the maximum fuzzy coalition game is proven to be the Choquet integral form on the condition that the associate crisp game is convex. In order to seek appropriate solutions for the proposed games based on a certain participation level, the Fuzzy-Shapley axioms are defined, and the explicit Shapley value is represented by the Shapley value of the associated crisp games. Moreover, the fuzzy core of this proposed fuzzy coalition game is the stable solution set for the given fuzzy coalition, which is also denoted by the crisp cores. Furthermore, we study the relationship between the Fuzzy-Shapley value and the fuzzy core. By adding restrictions on the fuzzy core, we propose a strong Fuzzy-core, which is a more stable solution than the fuzzy core. In addition, the fuzzy core is equivalent to the strong Fuzzy-core under some condition.\",\n \"Title: PCNN: Deep Convolutional Networks for Short-Term Traffic Congestion Prediction.\\nYear: 2018\\n\\nAbstract: Traffic problems have seriously affected people's life quality and urban development, and forecasting short-term traffic congestion is of great importance to both individuals and governments. However, understanding and modeling the traffic conditions can be extremely difficult, and our observations from real traffic data reveal that: 1) similar traffic congestion patterns exist in the neighboring ...\",\n \"Title: The extended Shapley value for generalized cooperative games under precedence constraints\\nYear: 2020\\n\\nAbstract: We introduce a new class of games where cooperation among players is restricted by precedence constraints vis á vis the worth of a coalition depends on the order in which the players enter into the coalition. The idea combines two existing classes of cooperative games, namely the cooperative games under precedence constraints due to Faigle and Kern (Int J Game Theory 21(3):249–266, 1992) and the games in generalized characteristic function due to Nowak and Radzik (Games Econ Behav 6(1):150–161, 1994). A Shapley value for this special class of games is proposed, we call it the extended Shapley value to distinguish it for the existing one. Two axiomatic characterizations of the extended Shapley value are given: one uses Efficiency, Null player, and Linearity; the other uses Efficiency, Marginality, and Null game. Some interesting properties of the extended Shapley value are studied. Furthermore, two extensions of the extended Shapley value, called the extended probabilistic value and the extended order value, are proposed and characterized. Our study shows that the results in cooperative games under precedence constraints cannot have a trivial extension to the generalized constrained games and conversely.\",\n \"Title: MPE: a mobility pattern embedding model for predicting next locations\\nYear: 2019\\n\\nAbstract: The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each record having at least three attributes: object ID, location ID, and time-stamp. In this paper, we propose a novel mobility pattern embedding model called MPE to shed the light on people’s mobility patterns in traffic trajectory data from multiple aspects, including sequential, personal, and temporal factors. MPE has two salient features: (1) it is capable of casting various types of information (object, location and time) to an integrated low-dimensional latent space; (2) it considers the effect of “phantom transitions” arising from road networks in traffic trajectory data. This embedding model opens the door to a wide range of applications such as next location prediction and visualization. Experimental results on two real-world datasets show that MPE is effective and outperforms the state-of-the-art methods significantly in a variety of tasks.\",\n \"Title: An efficient index structure for distributed k-nearest neighbours query processing\\nYear: 2020\\n\\nAbstract: Many location-based services are supported by the moving k-nearest neighbour (k-NN) query, which continuously returns the k-nearest data objects for a query point. Most of existing approaches to this problem have focused on a centralized setting, which show poor scalability to work around massive-scale and distributed data sets. In this paper, we propose an efficient distributed solution for k-NN query over moving objects to tackle the increasingly large scale of data. This approach includes a new grid-based index called Block Grid Index (BGI), and a distributed k-NN query algorithm based on BGI. There are three advantages of our approach: (1) BGI can be easily constructed and maintained in a distributed setting; (2) the algorithm is able to return the results set in only two iterations. (3) the efficiency of k-NN query is improved. The efficiency of our solution is verified by extensive experiments with millions of nodes.\",\n \"Title: Sliding Window Top-<Emphasis Type=\\\"Italic\\\">K</Emphasis> Monitoring over Distributed Data Streams\\nYear: 2017\\n\\nAbstract: Most of the traditional top-k algorithms are based on a single-server setting. They may be highly inefficient and/or cause huge communication overhead when applied to a distributed system environment. Therefore, the problem of top-k monitoring in distributed environments has been intensively investigated recently. This paper studies how to monitor the top-k data objects with the largest aggregate numeric values from distributed data streams within a fixed-size monitoring window W, while minimizing communication cost across the network. We propose a novel algorithm, which adaptively reallocates numeric values of data objects among distributed nodes by assigning revision factors when local constraints are violated and keeps the local top-k result at distributed nodes in line with the global top-k result. We also develop a framework that combines a distributed data stream monitoring architecture with a sliding window model. Based on this framework, extensive experiments are conducted on top of Apache Storm to verify the efficiency and scalability of the proposed algorithm.\",\n \"Title: An efficient index structure for distributed <Emphasis Type=\\\"Italic\\\">k</Emphasis>-nearest neighbours query processing\\nYear: 2020\\n\\nAbstract: Many location-based services are supported by the moving k-nearest neighbour (k-NN) query, which continuously returns the k-nearest data objects for a query point. Most of existing approaches to this problem have focused on a centralized setting, which show poor scalability to work around massive-scale and distributed data sets. In this paper, we propose an efficient distributed solution for k-NN query over moving objects to tackle the increasingly large scale of data. This approach includes a new grid-based index called Block Grid Index (BGI), and a distributed k-NN query algorithm based on BGI. There are three advantages of our approach: (1) BGI can be easily constructed and maintained in a distributed setting; (2) the algorithm is able to return the results set in only two iterations. (3) the efficiency of k-NN query is improved. The efficiency of our solution is verified by extensive experiments with millions of nodes.\",\n \"Title: Top-k Queries over Digital Traces\\nYear: 2019\\n\\nAbstract: Recent advances in social and mobile technology have enabled an abundance of digital traces (in the form of mobile check-ins, association of mobile devices to specific WiFi hotspots, etc.) revealing the physical presence history of diverse sets of entities (e.g., humans, devices, and vehicles). One challenging yet important task is to identify k entities that are most closely associated with a given query entity based on their digital traces. We propose a suite of indexing techniques and algorithms to enable fast query processing for this problem at scale. We first define a generic family of functions measuring the association between entities, and then propose algorithms to transform digital traces into a lower-dimensional space for more efficient computation. We subsequently design a hierarchical indexing structure to organize entities in a way that closely associated entities tend to appear together. We then develop algorithms to process top-k queries utilizing the index. We theoretically analyze the pruning effectiveness of the proposed methods based on a mobility model which we propose and validate in real life situations. Finally, we conduct extensive experiments on both synthetic and real datasets at scale, evaluating the performance of our techniques both analytically and experimentally, confirming the effectiveness and superiority of our approach over other applicable approaches across a variety of parameter settings and datasets.\",\n \"Title: Efficient Construction Of Nonlinear Models Over Normalized Data\\nYear: 2021\\n\\nAbstract: Machine Learning (ML) applications are proliferating in the enterprise. Relational data which are prevalent in enterprise applications are typically normalized; as a result, data has to be denormalized via primary/foreign-key joins to be provided as input to ML algorithms. In this paper, we study the implementation of popular nonlinear ML models, Gaussian Mixture Models (GMM) and Neural Networks (NN), over normalized data addressing both cases of binary and multi-way joins over normalized relations.For the case of GMM, we show how it is possible to decompose computation in a systematic way both for binary joins and for multi-way joins to construct mixture models. We demonstrate that by factoring the computation, one can conduct the training of the models much faster compared to other applicable approaches, without any loss in accuracy.For the case of NN, we propose algorithms to train the network taking normalized data as the input. Similarly, we present algorithms that can conduct the training of the network in a factorized way and offer performance advantages. The redundancy introduced by denormalization can be exploited for certain types of activation functions. However, we demonstrate that attempting to explore this redundancy is helpful up to a certain point; exploring redundancy at higher layers of the network will always result in increased costs and is not recommended.We present the results of a thorough experimental evaluation, varying several parameters of the input relations involved and demonstrate that our proposals for the training of GMM and NN yield drastic performance improvements typically starting at 100%, which become increasingly higher as parameters of the underlying data vary, without any loss in accuracy.\",\n \"Title: LES3: learning-based exact set similarity search\\nYear: 2021\\n\\nAbstract: AbstractSet similarity search is a problem of central interest to a wide variety of applications such as data cleaning and web search. Past approaches on set similarity search utilize either heavy indexing structures, incurring large search costs or indexes that produce large candidate sets. In this paper, we design a learning-based exact set similarity search approach, LES3. Our approach first partitions sets into groups, and then utilizes a light-weight bitmap-like indexing structure, called token-group matrix (TGM), to organize groups and prune out candidates given a query set. In order to optimize pruning using the TGM, we analytically investigate the optimal partitioning strategy under certain distributional assumptions. Using these results, we then design a learning-based partitioning approach called L2P and an associated data representation encoding, PTR, to identify the partitions. We conduct extensive experiments on real and synthetic datasets to fully study LES3, establishing the effectiveness and superiority over other applicable approaches.\",\n \"Title: An Intelligent Augmented Lifelike Avatar App for Virtual Physical Examination of Suspected Strokes\\nYear: 2021\\n\\nAbstract: An intelligent-augmented lifelike avatar mobile app (iLAMA) that integrates computer vision and sensor readings to automate and streamline the NIH Stroke Scale (NIHSS) physical examination is presented. The user interface design is optimized for elderly patients while the app showcases an animated lifelike 3D model of a friendly physician who walks the user through the exam. The standardized NIHSS examination included in iLAMA consists of five core tasks. The first two tasks involve rolling the eyes to the left and then to the right, and then smiling as wide as the user can. The app determines facial landmarks and analyzes the palsy of the face. The next task is to extend the arm and hold the phone at the shoulder level, and the smart phone gyroscope is used to detect acceleration to determine possible weakness in the arm. Next, the app tracks the location of the hand keypoints and determines possible ataxia based on the precision and accuracy of the locations of the touches. Finally, the app determines the user's forward acceleration in walking and possible imbalances using the accelerometer. The app then sends analyzed results of these tasks to the neurologist or stroke specialist for review and decisions.\",\n \"Title: Enabling the interpretability of pretrained venue representations using semantic categories\\nYear: 2022\\n\\nAbstract: The growing popularity of location-based social networks gives rise to a tremendous amount of social check-ins data, which are broadly used in previous studies to produce dense venue representations for various trajectory mining tasks. In this work, we focus on the interpretability of venue representations, an essential property that existing methods fail to provide. We propose two novel models to generate interpretable and easy-to-understand venue representations. The first model, CEM, is a category-aware (a category may be a restaurant, a mall, etc.) check-in embedding model and generates venue and category representations by capturing the sequential patterns of check-in records. With the second model, XEM, each dimension of the venue representation corresponds to a semantic anchor (i.e., a category) and can be interpreted as a coherent topic. We conduct extensive experiments using real-world check-in datasets for venue similarity computation and venue semantic annotation, and empirically show that introducing interpretability to the venue representations improves the performance of various downstream tasks.\",\n \"Title: PR-LTTE: Link travel time estimation based on path recovery from large-scale incomplete trip data\\nYear: 2022\\n\\nAbstract: •Estimate link travel time with large-scale incomplete vehicle trip data.•Propose a path-recovery-based method to iteratively estimate link travel time.•Conduct extensive experiments on two public large-scale vehicle trip datasets.\",\n \"Title: Embedding Hierarchical Structures for Venue Category Representation\\nYear: 2022\\n\\nAbstract: AbstractVenue categories used in location-based social networks often exhibit a hierarchical structure, together with the category sequences derived from users’ check-ins. The two data modalities provide a wealth of information for us to capture the semantic relationships between those categories. To understand the venue semantics, existing methods usually embed venue categories into low-dimensional spaces by modeling the linear context (i.e., the positional neighbors of the given category) in check-in sequences. However, the hierarchical structure of venue categories, which inherently encodes the relationships between categories, is largely untapped. In this article, we propose a venue Category Embedding Model named Hier-CEM, which generates a latent representation for each venue category by embedding the Hierarchical structure of categories and utilizing multiple types of context. Specifically, we investigate two kinds of hierarchical context based on any given venue category hierarchy and show how to model them together with the linear context collaboratively. We apply Hier-CEM to three tasks on two real check-in datasets collected from Foursquare. Experimental results show that Hier-CEM is better at capturing both semantic and sequential information inherent in venues than state-of-the-art embedding methods.\",\n \"Title: CAVE-SC: Inferring categories for venues using check-ins\\nYear: 2022\\n\\nAbstract: The categories of venues are labels, such as Museum and Bar, assigned to geographic locations. They are often incomplete and new venues may constantly arise, making automatic venue labeling essential. In this study, we proposed a category-aware venue embedding model with similarity constraints (CAVE-SC), which is an automatic feature engineering method to infer category labels for venues. CAVE-SC first models the co-occurrence relations between a given venue and its two types of sequential contexts (namely, the venue context and the category context) based on a softmax loss and then projects both venues and categories into the same latent space. Furthermore, CAVE-SC models the similarity constraints posed by the relationships between venues and their categories based on a newly designed triplet loss, assuming that the distance between a venue and its category is smaller than the distance between the venue and a randomly sampled category in the embedding space. Finally, linear interpolation is used to balance the two losses, thereby generating discriminative feature representations of venues. Venue labeling can be performed based on the distances between venue representations and category representations. Extensive experiments on two check-in datasets demonstrate the superiority of CAVE-SC over the baseline methods.\",\n \"Title: Ranked Window Query Retrieval over Video Repositories\\nYear: 2022\\n\\nAbstract: Recent advances in Computer Vision have contributed to solid accuracy and efficiency improvements in many tasks such as object detection and tracking, enabling new opportunities for video analytics. In this paper, we initiate the study of ranked window queries that aim to retrieve clips from large video repositories in which objects co-occur in a queryspecified fashion. For example, ranked window queries allow retrieval of clips of a set duration (e.g., 10 seconds) with the highest score from a long video, where at least the same 3 cars (with matching conditions based on suitably defined metadata) appear jointly. To answer such queries, we propose a two-phased approach, which builds indexes for all desired objects of the given videos during an Ingestion Phase and evaluates query answers efficiently in the Query Phase. During the Ingestion Phase, the proposed Partition-Based Index Construction (PBIC) algorithm builds indexes on partitions obtained by splitting each given video. Leveraging such indexes, queries are answered in the Query Phase using the Partition-Based Query Processing (PBQP) algorithm, which efficiently produces the desired (queryspecified) number of results with the highest scores. We present the outcome of a thorough performance study on real videos that evaluates the performance of the proposed algorithms by varying parameters of interest. Our results indicate that the proposed set of techniques are capable of processing queries efficiently at scale, demonstrating multiple orders of magnitude speedups over other applicable approaches.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":86,"string":"86"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":273,"string":"273"}}},{"rowIdx":274,"cells":{"question_id":{"kind":"string","value":"Henrik Sandberg"},"question":{"kind":"string","value":"Generate an abstract for the title \"Control Theory for Practical Cyber-Physical Security: Extended Abstract.\" using the following items: 1. Control theory\n2. Secure cyber-physical systems\n3. False-data injection attacks\n4. Resilient control scheme\n5. Microgrid energy management system"},"answer":{"kind":"string","value":"In this talk, we discuss how control theory can contribute to the analysis and design of secure cyber-physical systems. We start by reviewing conditions for undetectable false-data injection attacks on feedback control systems. In particular, we highlight how a physical understanding of the controlled process can guide us in the allocation of protective measures. We show that protecting only a few carefully selected actuators or sensors can give indirect protection to many more components. We then illustrate how such analysis is exploited in the design of a resilient control scheme for a microgrid energy management system."},"correct_answer":{"kind":"string","value":"In this talk, we discuss how control theory can contribute to the analysis and design of secure cyber-physical systems. We start by reviewing conditions for undetectable false-data injection attacks on feedback control systems. In particular, we highlight how a physical understanding of the controlled process can guide us in the allocation of protective measures. We show that protecting only a few carefully selected actuators or sensors can give indirect protection to many more components. We then illustrate how such analysis is exploited in the design of a resilient control scheme for a microgrid energy management system."},"documents":{"kind":"list like","value":["Title: Revealing stealthy attacks in control systems.\nYear: 2012\n\nAbstract: In this paper the problem of revealing stealthy data-injection attacks on control systems is addressed. In particular we consider the scenario where the attacker performs zero-dynamics attacks on the system. First, we characterize and analyze the stealthiness properties of these attacks for linear time-invariant systems. Then we tackle the problem of detecting such attacks by modifying the system's structure. Our results provide necessary and sufficient conditions that the modifications should satisfy in order to detect the zero-dynamics attacks. The results and proposed detection methods are illustrated through numerical examples.","Title: A Cyber Security Study of a SCADA Energy Management System: Stealthy Deception Attacks on the State Estimator\nYear: 2010\n\nAbstract: The electrical power network is a critical infrastructure in today's society,\nso its safe and reliable operation is of major concern. State estimators are\ncommonly used in power networks, for example, to detect faulty equipment and to\noptimally route power flows. The estimators are often located in control\ncenters, to which large numbers of measurements are sent over unencrypted\ncommunication channels. Therefore cyber security for state estimators becomes\nan important issue. In this paper we analyze the cyber security of state\nestimators in supervisory control and data acquisition (SCADA) for energy\nmanagement systems (EMS) operating the power network. Current EMS state\nestimation algorithms have bad data detection (BDD) schemes to detect outliers\nin the measurement data. Such schemes are based on high measurement redundancy.\nAlthough these methods may detect a set of basic cyber attacks, they may fail\nin the presence of an intelligent attacker. We explore the latter by\nconsidering scenarios where stealthy deception attacks are performed by sending\nfalse information to the control center. We begin by presenting a recent\nframework that characterizes the attack as an optimization problem with the\nobjective specified through a security metric and constraints corresponding to\nthe attack cost. The framework is used to conduct realistic experiments on a\nstate-of-the-art SCADA EMS software for a power network example with 14\nsubstations, 27 buses, and 40 branches. The results indicate how state\nestimators for power networks can be made more resilient to cyber security\nattacks.","Title: Design of State-based Schedulers for a Network of Control Loops\nYear: 2012\n\nAbstract: For a closed-loop system with a contention-based multiple access network on its sensor link, the medium access controller (MAC) may discard some packets when the traffic on the link is high. We use a local state-based scheduler to select a few critical data packets to send to the MAC. In this paper, we analyze the impact of such a scheduler on the closed-loop system in the presence of traffic, and show that there is a dual effect with state-based scheduling. In general, this makes the optimal scheduler and controller hard to find. However, by removing past controls from the scheduling criterion, we find that certainty equivalence holds. This condition is related to the classical result of Bar-Shalom and Tse, and it leads to the design of an innovations-based scheduler with a certainty equivalent controller. However, this controller is not an equivalent design for the optimal controller, in the sense of Witsenhausen. The computation of the estimate can be simplified by introducing a symmetry constraint on the scheduler. Based on these findings, we propose a dual predictor architecture for the closed-loop system, which ensures separation between scheduler, observer and controller. We present an example of this architecture, which illustrates a network-aware event-triggering mechanism.","Title: Stability analysis of multiple state-based schedulers with CSMA.\nYear: 2012\n\nAbstract: In this paper, we identify sufficient conditions for Lyapunov Mean Square Stability (LMSS) of a contention-based network of first-order systems, with state-based schedulers. The stability analysis helps us to choose policies for adapting the scheduler threshold to the delay from the network and scheduler. We show that three scheduling laws can result in LMSS: constant-probability laws and additively increasing or decreasing probability laws. Our results counter the notions that increasing probability scheduling laws alone can guarantee stability of the closed-loop system, or that decreasing probability scheduling laws are required to mitigate congestion in the network.","Title: On Lossless Approximations, the Fluctuation-Dissipation Theorem, and Limitations of Measurements\nYear: 2011\n\nAbstract: In this paper, we take a control-theoretic approach to answering some\nstandard questions in statistical mechanics, and use the results to derive\nlimitations of classical measurements. A central problem is the relation\nbetween systems which appear macroscopically dissipative but are\nmicroscopically lossless. We show that a linear system is dissipative if, and\nonly if, it can be approximated by a linear lossless system over arbitrarily\nlong time intervals. Hence lossless systems are in this sense dense in\ndissipative systems. A linear active system can be approximated by a nonlinear\nlossless system that is charged with initial energy. As a by-product, we obtain\nmechanisms explaining the Onsager relations from time-reversible lossless\napproximations, and the fluctuation-dissipation theorem from uncertainty in the\ninitial state of the lossless system. The results are applied to measurement\ndevices and are used to quantify limits on the so-called observer effect, also\ncalled back action, which is the impact the measurement device has on the\nobserved system. In particular, it is shown that deterministic back action can\nbe compensated by using active elements, whereas stochastic back action is\nunavoidable and depends on the temperature of the measurement device.","Title: The Statistical Mechanics Of Fluctuation-Dissipation And Measurement Back Action\nYear: 2007\n\nAbstract: In this paper, we take a control-theoretic approach to answering some standard questions in statistical mechanics. A central problem is the relation between systems which appear macroscopically dissipative but are microscopically lossless. We show that a linear macroscopic system is dissipative if and only if it can be approximated by a linear lossless microscopic system, over arbitrarily long time intervals. As a by-product, we obtain mechanisms explaining Johnson-Nyquist noise as initial uncertainty in the lossless state, as well as measurement back action and a trade-off between process and measurement noise.","Title: Stability Analysis and Design of a Network of Event-based Systems.\nYear: 2014\n\nAbstract: We consider a network of event-based systems that use a shared wireless medium to communicate with their respective controllers. These systems use a contention resolution mechanism to arbitrate access to the shared network. We identify sufficient conditions for Lyapunov mean square stability of each control system in the network, and design event-based policies that guarantee it. Our stability analysis is based on a Markov model that removes the network-induced correlation between the states of the control systems in the network. Analyzing the stability of this Markov model remains a challenge, as the event-triggering policy renders the estimation error non-Gaussian. Hence, we identify an auxiliary system that furnishes an upper bound for the variance of the system states. Using the stability analysis, we design policies, such as the constant-probability policy, for adapting the event-triggering thresholds to the delay in accessing the network. Realistic wireless networked control examples illustrate the applicability of the presented approach.","Title: Computing the L2 gain for linear periodic continuous-time systems\nYear: 2009\n\nAbstract: A method to compute the L2 gain is developed for the class of linear periodic continuous-time systems that admit a finite-dimensional state-space realisation. A bisection search for the smallest upper bound on the gain is employed, where at each step an equivalent discrete-time problem is considered via the well-known technique of time-domain lifting. The equivalent problem involves testing a bound on the gain of a linear shift-invariant discrete-time system, with the same state dimension as the periodic continuous-time system. It is shown that a state-space realisation of the discrete-time system can be constructed from point solutions to a linear differential equation and two differential Riccati equations, all subject to only single-point boundary conditions. These are well behaved over the corresponding one period intervals of integration, and as such, the required point solutions can be computed via standard methods for ordinary differential equations. A numerical example is presented and comparisons made with alternative techniques.","Title: Scheduling smart home appliances using mixed integer linear programming\nYear: 2011\n\nAbstract: This paper considers the minimum electricity cost scheduling problem of smart home appliances. Operation characteristics, such as expected duration and peak power consumption of the smart appliances, can be adjusted through a power profile signal. The optimal power profile signal minimizes cost, while satisfying technical operation constraints and consumer preferences. Constraints such as enforcing uninterruptible and sequential operations are modeled in the proposed framework using mixed integer linear programming (MILP). Several realistic scenarios based on actual spot price are considered, and the numerical results provide insight into tariff design. Computational issues and extensions of the proposed scheduling framework are also discussed.","Title: A bode sensitivity integral for linear time-periodic systems\nYear: 2005\n\nAbstract: Bode's sensitivity integral is a well-known formula that quan- tifies some of the limitations in feedback control for linear time-invariant systems. In this note, we show that there is a similar formula for linear time-periodic systems. The harmonic transfer function is used to prove the result. We use the notion of roll-off 2, which means that the first time- varying Markov parameter is equal to zero. It then follows that the har- monic transfer function is an analytic operator and a trace class operator. These facts are used to prove the result.","Title: Model reduction of networked passive systems through clustering\nYear: 2013\n\nAbstract: In this paper, a model reduction procedure for a network of interconnected identical passive subsystems is presented. Here, rather than performing model reduction on the subsystems, adjacent subsystems are clustered, leading to a reduced-order networked system that allows for a convenient physical interpretation. The identification of the subsystems to be clustered is performed through controllability and observability analysis of an associated edge system and it is shown that the property of synchronization (i.e., the convergence of trajectories of the subsystems to each other) is preserved during reduction. The results are illustrated by means of an example.","Title: Distributed fault detection for interconnected second-order systems.\nYear: 2011\n\nAbstract: In this paper, the existence of unknown input observers for networks of interconnected second-order linear time invariant systems is studied. Two classes of distributed control systems of large practical relevance are considered. It is proved that for these systems, one can construct a bank of unknown input observers, and use them to detect and isolate faults in the network. The result presents a distributed implementation. In particular, by exploiting the system structure, this work provides further insight into the design of UIO for networked systems. Moreover, the importance of certain network measurements is shown. Infeasibility results with respect to available measurements and faults are also provided, as well as methods to remove faulty agents from the network. Applications to power networks and robotic formations are presented. It is shown how the developed methodology apply to a power network described by the swing equation with a faulty bus. For a multi-robot system, it is illustrated how a faulty robot can be detected and removed.","Title: Performance Analysis of a Network of Event-based Systems.\nYear: 2014\n\nAbstract: We consider a scenario where multiple event-based systems use a contention resolution mechanism (CRM) to communicate with their respective controllers over a wireless network. We present a Markov model that captures the joint interactions of the event-triggering policy and the CRM. This model is obtained by decoupling interactions between the different systems in the network, drawing inspiration from Bianchi's analysis of IEEE 802.11. We present Monte-Carlo simulations that validate our model under various network configurations, and verify the accuracy of the performance analysis.","Title: Challenges in Power System Information Security\nYear: 2012\n\nAbstract: Achieving all-encompassing component-level security in power system IT infrastructures is difficult, owing to its cost and potential performance implications.","Title: Agents misbehaving in a network: a vice or a virtue?\nYear: 2012\n\nAbstract: Misbehaviors among the agents in a network might be intentional or unintentional, they might cause a system-wide failure or they might improve the performance or even enable us to achieve an objective. In this article we consider examples of these possible scenarios. First, we argue the necessity of monitoring the agents in a network to detect if they are misbehaving or not and outline a distribut...","Title: Electric power network security analysis via minimum cut relaxation\nYear: 2011\n\nAbstract: In this paper an efficient computation scheme for analyzing the security of power transmission networks is presented. In order to strategically allocate protection devices in the network, the problem of finding the sparsest stealthy false data attack to the state estimator is studied. While the attack search problem is traditionally solved as a generic constrained cardinality minimization problem, this paper exploits the problem structure intrinsic to the power network application to obtain a polynomial time approximate algorithm based on a minimum cut relaxation. Experiment results from realistic test cases are presented to demonstrate the efficiency and accuracy of the proposed algorithm.","Title: Cyber-security of SCADA systems\nYear: 2012\n\nAbstract: After a general introduction of the VIKING EU FP7 project two specific cyber-attack mechanisms, which have been analyzed in the VIKING project, will be discussed in more detail. Firstly an attack and its consequences on the Automatic Generation Control (AGC) in a power system are investigated, and secondly the cyber security of State Estimators in SCADA systems is scrutinized.","Title: Controllability of a class of networked passive linear systems\nYear: 2013\n\nAbstract: In this paper, controllability properties of networks of diffusively coupled linear systems are considered through the controllability Gramian. For a class of passive linear systems, it is shown that the controllability Gramian can be decomposed into two parts. The first part is related to the dynamics of the individual systems whereas the second part is dependent only on the interconnection topology, allowing for a clear interpretation and efficient computation of controllability properties for a class of networked systems. Moreover, a relation between symmetries in the interconnection topology and controllability is given. The results are illustrated by an example.","Title: Linear-Quadratic-Gaussian Heat Engines\nYear: 2007\n\nAbstract: In this paper, we study the problem of extracting work from heat flows. In thermodynamics, a device doing this is called a heat engine. A fundamental problem is to derive hard limits on the efficiency of heat engines. Here we construct a linear-quadratic-Gaussian optimal controller that estimates the states of a heated lossless system. The measurements cool the system, and the surplus energy can be extracted as work by the controller. Hence, the controller acts like a Maxwell's demon. We compute the efficiency of the controller over finite and infinite time intervals, and since the controller is optimal, this yields hard limits. Over infinite time horizons, the controller has the same efficiency as a Carnot heat engine, and thereby it respects the second law of thermodynamics. As illustration we use an electric circuit where an ideal current source extracts energy from resistors with Johnson-Nyquist noise.","Title: A case study in model reduction of linear time-varying systems\nYear: 2006\n\nAbstract: In this paper, the balanced truncation procedure is applied to time-varying linear systems, both in continuous and in discrete time. The methods are applied to a linear approximation of a diesel exhaust catalyst model. The reduced-order systems are obtained by using certain projections instead of direct balancing. An approximate zero-order-hold discretization of continuous-time systems is described, and a new a priori approximation error bound for balanced truncation in the discrete-time case is obtained. The case study shows that there are several advantages to work in discrete time. It gives simpler implementation with fewer computations.","Title: Network-Aware Mitigation of Data Integrity Attacks on Power System State Estimation.\nYear: 2012\n\nAbstract: Critical power system applications like contingency analysis and optimal power flow calculation rely on the power system state estimator. Hence the security of the state estimator is essential for the proper operation of the power system. In the future more applications are expected to rely on it, so that its importance will increase. Based on realistic models of the communication infrastructure used to deliver measurement data from the substations to the state estimator, in this paper we investigate the vulnerability of the power system state estimator to attacks performed against the communication infrastructure. We define security metrics that quantify the importance of individual substations and the cost of attacking individual measurements. We propose approximations of these metrics, that are based on the communication network topology only, and we compare them to the exact metrics. We provide efficient algorithms to calculate the security metrics. We use the metrics to show how various network layer and application layer mitigation strategies, like single and multi-path routing and data authentication, can be used to decrease the vulnerability of the state estimator. We illustrate the efficiency of the algorithms on the IEEE 118 and 300 bus benchmark power systems.","Title: Active actuator fault detection and diagnostics in HVAC systems.\nYear: 2012\n\nAbstract: This paper introduces a new method for performing actuator fault detection and diagnostics (FDD) in heating ventilation and air conditioning (HVAC) systems. The proposed actuator FDD strategy, for testing whether an actuator is stuck in a single position, uses a two-tier approach that includes a dynamic model-based detector and a fast-deciding steady-state detector. The model-based detector is formulated to provide detection performance that asymptotically bounds both the probability of miss and probability of false alarm. To provide a quick confirmation the actuator is working, the steady-state detector utilizes a goodness-of-fit detection strategy to decide if the measurements could be described by an actuator failure. An architecture is introduced that requires multiple steady-state detection experiments to decide that the measurements could be explained by an actuator failure before performing model-based detection. An experimental test bed using a the KTH Royal Institute of Technology campus HVAC system is described and used to evaluate the steady-state and model-based detectors. The experimental test bed is utilized to identify a building dynamics model, that is employed through monte carlo analysis, to characterize the detection performance of both the model-based detector and the steady-state detector.","Title: Fault Detection and Mitigation in Kirchhoff Networks.\nYear: 2012\n\nAbstract: In this letter, we study the problem of fault detection and mitigation in networks where the measurements satisfy Kirchhoff's voltage law. First, we characterise the class of faults appearing as an additive fault vector (injected by a malicious adversary or due to equipment failures) that can be detected by taking into account the topology of the network. Second, we consider the problem of estimat...","Title: Computing Critical $k$-tuples in Power Networks\nYear: 2012\n\nAbstract: In this paper the problem of finding the sparsest (i.e., minimum cardinality) critical k-tuple including one arbitrarily specified measurement is considered. The solution to this problem can be used to identify weak points in the measurement set, or aid the placement of new meters. The critical k-tuple problem is a combinatorial generalization of the critical measurement calculation problem. Using...","Title: On performance limitations of congestion control\nYear: 2009\n\nAbstract: Fundamental performance limitations on congestion control is discussed in relation to the information that is available in the controller. Three control architectures that all use bottle-neck buffer delay information of various form as inputs and sending rate as outputs are considered. It is shown that feedback delays from buffer to senders set limits on the achievable performance measured through fairness, efficiency and stability. We apply our findings to TCP FAST and can make some new interesting control theoretic interpretations of that protocol.","Title: On Floquet-Fourier Realizations Of Linear Time-Periodic Impulse Responses\nYear: 2006\n\nAbstract: We show that a linear time-periodic system with a smooth impulse response can be arbitrarily well approximated by a linear time-periodic state-space representation in so-called Floquet-Fourier form. The Floquet-Fourier form has a constant state matrix and the input and output matrices have only finitely many nonzero Fourier coefficients. Such representations are easier to use for analysis and control design than the impulse response or fully general state-space forms. The construction of the Floquet-Fourier form is done using methods for model approximation of infinite-dimensional linear time-invariant systems. We also propose a method for constructing minimal realizations from impulse responses of a special structure.","Title: Complexity reduction for parameter-dependent linear systems\nYear: 2012\n\nAbstract: We present a complexity reduction algorithm for a family of parameter-dependent linear systems when the system parameters belong to a compact semi-algebraic set. This algorithm potentially describes the underlying dynamical system with fewer parameters or state variables. To do so, it minimizes the distance (i.e., H∞-norm of the difference) between the original system and its reduced version. We present a sub-optimal solution to this problem using sum-of-squares optimization methods. We present the results for both continuous-time and discrete-time systems. Lastly, we illustrate the applicability of our proposed algorithm on numerical examples.","Title: On the Exact Solution to a Smart Grid Cyber-Security Analysis Problem\nYear: 2013\n\nAbstract: This paper considers a smart grid cyber-security problem analyzing the vulnerabilities of electric power networks to false data attacks. The analysis problem is related to a constrained cardinality minimization problem. The main result shows that an relaxation technique provides an exact optimal solution to this cardinality minimization problem. The proposed result is based on a polyhedral combinatorics argument. It is different from well-known results based on mutual coherence and restricted isometry property. The results are illustrated on benchmarks including the IEEE 118-bus, IEEE 300-bus, and the Polish 2383-bus and 2736-bus systems.","Title: The Meaning of Structure in Interconnected Dynamic Systems\nYear: 2011\n\nAbstract: Interconnected dynamic systems are a pervasive component of our modern infrastructures. The complexity of such systems can be staggering, which motivates simplified representations for their manipulation and analysis. This work introduces the complete computational structure of a system as a common baseline for comparing different simplified representations. Linear systems are then used as a vehicle for comparing and contrasting distinct partial structure representations. Such representations simplify the description of a system's complete computational structure at various levels of fidelity while retaining a full description of the system's input-output dynamic behavior. Relationships between these various partial structure representations are detailed, and the landscape of new realization, minimality, and model reduction problems introduced by these representations is briefly surveyed.","Title: The conservation of information, towards an axiomatized modular modeling approach to congestion control\nYear: 2013\n\nAbstract: We derive a modular fluid-flow network congestion control model based on a law of fundamental nature in networks: the conservation of information. Network elements such as queues, users, and transmission channels and network performance indicators like sending/acknowledgment rates and delays are mathematically modeled by applying this law locally. Our contributions are twofold. First, we introduce a modular metamodel that is sufficiently generic to represent any network topology. The proposed model is composed of building blocks that implement mechanisms ignored by the existing ones, which can be recovered from exact reduction or approximation of this new model. Second, we provide a novel classification of previously proposed models in the literature and show that they are often not capable of capturing the transient behavior of the network precisely. Numerical results obtained from packet-level simulations demonstrate the accuracy of the proposed model.","Title: Data Attack Isolation in Power Networks Using Secure Voltage Magnitude Measurements\nYear: 2014\n\nAbstract: In this paper a procedure to detect and isolate data attacks on power network power flow measurements is proposed. This method can be used in conjunction with available bad data detection (BDD) methods to isolate multiple bad data which are otherwise difficult to handle. The proposed procedure relies on secure measurements of bus voltage magnitudes to define a measurement residual using potentially compromised active and reactive power flow measurements on transmission lines. The proposed residual can be calculated in real-time. In addition, the component of the proposed residual on any particular line depends only locally on the component of the data attack on the same line. This makes the proposed residual well-suited for distributed data attack isolation in large-scale power networks. Furthermore, it can be shown that the proposed procedure becomes more effective when measurements from multiple time instances can be utilized. A detailed numerical case study on the IEEE 14-bus benchmark system demonstrates the effectiveness of the proposed procedure.","Title: Attack models and scenarios for networked control systems\nYear: 2012\n\nAbstract: Cyber-secure networked control is modeled, analyzed, and experimentally illustrated in this paper. An attack space defined by the adversary's system knowledge, disclosure, and disruption resources is introduced. Adversaries constrained by these resources are modeled for a networked control system architecture. It is shown that attack scenarios corresponding to replay, zero dynamics, and bias injection attacks can be analyzed using this framework. An experimental setup based on a quadruple-tank process controlled over a wireless network is used to illustrate the attack scenarios, their consequences, and potential counter-measures.","Title: Frequency-Weighted Model Reduction With Applications To Structured Models\nYear: 2007\n\nAbstract: In this paper, a frequency-weighted extension of a recently proposed model reduction method for linear systems is presented. The method uses convex optimization and can be used both with sample data and exact models. We also obtain bounds on the frequency-weighted error. The method is combined with a rank-minimization heuristic to approximate multi-input-multi-output systems. We also present two applications environment compensation and simplification of interconnected models - where we argue the proposed methods are useful.","Title: Structured Model Order Reduction of Parallel Models in Feedback.\nYear: 2013\n\nAbstract: Parallel working units in closed-loop operation are frequently encountered in industrial applications of advanced process control (boilers, turbines, chemical reactors, etc.). Control strategies typically require different low-order models for each configuration of parallel units. These different models are usually obtained by heuristics applied to the parallel models. To replace these heuristics, this paper proposes a systematic solution based on structured model order reduction. Two methods are considered, the first has general applicability to stable closed-loop systems, but gives no a priori error bounds; the second linear matrix inequality (LMI)-based method comes with an explicit error bounds, but cannot be applied to general models. However, it is shown that for models composed of cascades of stable subsystems and negative feedbacks of strictly positive real subsystems, the LMIs are always feasible. Both methods are demonstrated on a practical example of a cogeneration power plant with multiple boilers. It is proved that the second LMI-based method can always be applied to general problems with structures similar to the boiler-header systems considered in this paper.","Title: An Axiomatic Fluid-Flow Model For Congestion Control Analysis\nYear: 2011\n\nAbstract: An axiomatic model for congestion control is derived. The proposed four axioms serve as a basis for the construction of models for the network elements. It is shown that, under some assumptions, some models of the literature can be recovered. A single-buffer/multiple-users topology is finally derived and studied for illustration.","Title: Efficient Computations of a Security Index for False Data Attacks in Power Networks.\nYear: 2014\n\nAbstract: The resilience of Supervisory Control and Data Acquisition (SCADA) systems for electric power networks for certain cyber-attacks is considered. We analyze the vulnerability of the measurement system to false data attack on communicated measurements. The vulnerability analysis problem is shown to be NP-hard, meaning that unless P=NP there is no polynomial time algorithm to analyze the vulnerability of the system. Nevertheless, we identify situations, such as the full measurement case, where the analysis problem can be solved efficiently. In such cases, we show indeed that the problem can be cast as a generalization of the minimum cut problem involving nodes with possibly nonzero costs. We further show that it can be reformulated as a standard minimum cut problem (without node costs) on a modified graph of proportional size. An important consequence of this result is that our approach provides the first exact efficient algorithm for the vulnerability analysis problem under the full measurement assumption. Furthermore, our approach also provides an efficient heuristic algorithm for the general NP-hard problem. Our results are illustrated by numerical studies on benchmark systems including the IEEE 118-bus system.","Title: Dissipativity-Preserving Model Reduction for Large-Scale Distributed Control Systems\nYear: 2015\n\nAbstract: We propose a dissipativity-preserving structured model reduction method for distributed control systems. As a fundamental tool to develop structured model reduction, we first establish dissipativity-preserving model reduction for general linear systems on the basis of a singular perturbation approximation. To this end, by deriving a tractable expression of singular perturbation models, we characterize dissipativity preservation in terms of a projection-like transformation of storage functions, and we show that the resultant approximation error is relevant to the sum of neglected eigenvalues of an index matrix. Next, utilizing this dissipativity-preserving model reduction, we develop a structured controller reduction method for distributed control systems. The major significance of this method is to preserve the spatial distribution of dissipative controllers and to provide an a priori bound for the performance degradation of closed-loop systems in terms of the H2-norm. The efficiency of the proposed method is verified through a numerical example of vibration suppression control for interconnected second-order systems.","Title: Simplify: A Toolbox For Structured Model Reduction\nYear: 2014\n\nAbstract: In this paper, we present a toolbox for structured model reduction developed for MATLAB. In addition to structured model reduction methods using balanced realizations of the subsystems, we introduce a numerical algorithm for structured model reduction using a subgradient optimization algorithm. We briefly present the syntax for the toolbox and its features. Finally, we demonstrate the applicability of various model reduction methods in the toolbox on a structured mass-spring mechanical system.","Title: Multiple-Loop Self-Triggered Model Predictive Control for Network Scheduling and Control\nYear: 2015\n\nAbstract: We present an algorithm for controlling and scheduling multiple linear time-invariant processes on a shared bandwidth-limited communication network using adaptive sampling intervals. The controller is centralized and not only computes at every sampling instant the new control command for a process but also decides the time interval to wait until taking the next sample.The approach relies on model predictive control ideas, where the cost function penalizes the state and control effort as well as the time interval until the next sample is taken. The latter is introduced to generate an adaptive sampling scheme for the overall system such that the sampling time increases as the norm of the system state goes to zero. This paper presents a method for synthesizing such a predictive controller and gives explicit sufficient conditions for when it is stabilizing. Further explicit conditions are given that guarantee conflict free transmissions on the network. It is shown that the optimization problem may be solved offline and that the controller can be implemented as a lookup table of state feedback gains. The simulation studies which compare the proposed algorithm to periodic sampling illustrate potential performance gains.","Title: Approximative model reconstruction of cascade systems.\nYear: 2014\n\nAbstract: This letter considers how to approximately reconstruct a cascade system from a given unstructured system estimate. Many system identification methods, including subspace methods, provide reliable but generally unstructured black-box models. The problem we consider is how to find cascade systems that are close to such black-box models. For this, we use model matching techniques and optimal weighted Hankel-norm approximation to obtain accurate low-order cascade systems. We show that it is possible to bound the reconstruction error in terms of an error tolerance parameter and weighted Hankel singular values. The suggested methods are illustrated on both a numerical example and a real double tank system with experimental data.","Title: A secure control framework for resource-limited adversaries.\nYear: 2015\n\nAbstract: Cyber-secure networked control is modeled, analyzed, and experimentally illustrated in this paper. An attack space defined by the adversary’s model knowledge, disclosure, and disruption resources is introduced. Adversaries constrained by these resources are modeled for a networked control system architecture. It is shown that attack scenarios corresponding to denial-of-service, replay, zero-dynamics, and bias injection attacks on linear time-invariant systems can be analyzed using this framework. Furthermore, the attack policy for each scenario is described and the attack’s impact is characterized using the concept of safe sets. An experimental setup based on a quadruple-tank process controlled over a wireless network is used to illustrate the attack scenarios, their consequences, and potential counter-measures.","Title: Distributed PI-control with applications to power systems frequency control\nYear: 2014\n\nAbstract: This paper considers a distributed PI-controller for networked dynamical systems. Sufficient conditions for when the controller is able to stabilize a general linear system and eliminate static control errors are presented. The proposed controller is applied to frequency control of power transmission systems. Sufficient stability criteria are derived, and it is shown that the controller parameters can always be chosen so that the frequencies in the closed loop converge to nominal operational frequency. We show that the load sharing property of the generators is maintained, i.e., the input power of the generators is proportional to a controller parameter. The controller is evaluated by simulation on the IEEE 30 bus test network, where its effectiveness is demonstrated.","Title: Energy and CO2 efficient scheduling of smart appliances in active houses equipped with batteries\nYear: 2014\n\nAbstract: In this paper, we present a novel method for scheduling smart appliances and batteries, in order to reduce both the electricity bill and the CO2 emissions. Mathematically, the scheduling problem is posed as a multi-objective Mixed Integer Linear Programming (MILP), which can be solved by using standard algorithms. A case study is performed to assess the performance of the proposed scheduling framework. Numerical results show that the new formulation can decrease both the CO2 emissions and the electricity bill. Furthermore, a survey of studies that deal with scheduling of smart appliances is provided. These papers use methods based on MILP, Dynamic Programming (DP), and Minimum Cut Algorithm (MCA) for solving the scheduling problem. We discuss their performance in terms of computation time and optimality versus time discretization and number of appliances.","Title: Wiretap codes for secure multi-party computation\nYear: 2014\n\nAbstract: In this paper, we propose a new secret sharing scheme for secure multi-party computation. We present a general framework that allows us to construct efficient secret sharing schemes from channel coding techniques for the wiretap channel. The resulting schemes can be employed to securely calculate linear functions of data that are distributed in a network without leaking any information on the data except the desired result. For the examples considered in this paper, our schemes minimize the communication overhead while keeping the data perfectly secure. Compared to conventional schemes, for which the communication overhead grows quadratically in the number of clients in the considered scenarios, the communication overhead for our approach grows only linearly with the number of clients. This property is maintained even if our secret sharing scheme is set up to introduce redundancy in order to compensate for losses of secret shares. While we only consider the case of passive eavesdroppers and implementations based on nested Reed-Solomon codes in this paper, the proposed framework can also be applied in other cases (e.g., when clients tamper with the data) by taking into account the effects of attacks in the design of the underlying wiretap code.","Title: Distributed Control of Networked Dynamical Systems: Static Feedback, Integral Action and Consensus\nYear: 2014\n\nAbstract: This paper analyzes distributed control protocols for first- and second-order networked dynamical systems. We propose a class of nonlinear consensus controllers where the input of each agent can be written as a product of a nonlinear gain, and a sum of nonlinear interaction functions. By using integral Lyapunov functions, we prove the stability of the proposed control protocols, and explicitly characterize the equilibrium set. We also propose a distributed proportional-integral (PI) controller for networked dynamical systems. The PI controllers successfully attenuate constant disturbances in the network. We prove that agents with single-integrator dynamics are stable for any integral gain, and give an explicit tight upper bound on the integral gain for when the system is stable for agents with double-integrator dynamics. Throughout the paper we highlight some possible applications of the proposed controllers by realistic simulations of autonomous satellites, power systems and building temperature control.","Title: Distributed Fault Detection and Isolation Resilient to Network Model Uncertainties\nYear: 2014\n\nAbstract: The ability to maintain state awareness in the face of unexpected and unmodeled errors and threats is a defining feature of a resilient control system. Therefore, in this paper, we study the problem of distributed fault detection and isolation (FDI) in large networked systems with uncertain system models. The linear networked system is composed of interconnected subsystems and may be represented as a graph. The subsystems are represented by nodes, while the edges correspond to the interconnections between subsystems. Considering faults that may occur on the interconnections and subsystems, as our first contribution, we propose a distributed scheme to jointly detect and isolate faults occurring in nodes and edges of the system. As our second contribution, we analyze the behavior of the proposed scheme under model uncertainties caused by the addition or removal of edges. Additionally, we propose a novel distributed FDI scheme based on local models and measurements that is resilient to changes outside of the local subsystem and achieves FDI. Our third contribution addresses the complexity reduction of the distributed FDI method, by characterizing the minimum amount of model information and measurements needed to achieve FDI and by reducing the number of monitoring nodes. The proposed methods can be fused to design a scalable and resilient distributed FDI architecture that achieves local FDI despite unknown changes outside the local subsystem. The proposed approach is illustrated by numerical experiments on the IEEE 118-bus power network benchmark.","Title: Control of MTDC transmission systems under local information\nYear: 2014\n\nAbstract: High-voltage direct current (HVDC) is a commonly used technology for long-distance electric power transmission, mainly due to its low resistive losses. In this paper a distributed controller for multi-terminal high-voltage direct current (MTDC) transmission systems is considered. Sufficient conditions for when the proposed controller renders the closed-loop system asymptotically stable are provided. Provided that the closed loop system is asymptotically stable, it is shown that in steady-state a weighted average of the deviations from the nominal voltages is zero. Furthermore, a quadratic cost of the current injections is minimized asymptotically.","Title: Model reduction of linear systems using extended balanced truncation\nYear: 2008\n\nAbstract: An extension to balanced truncation is presented. Balanced truncation is a standard method for model reduction and it has many good properties, such as preservation of model stability and a priori error bounds. Balanced truncation is done using controllability and observability Gramians. The Gramians can be found by solving a set of linear matrix inequalities. In this paper, we show that these linear matrix inequalities can be extended so that the number of decision variables are at least doubled. This leads to the concept of extended Gramians. It is shown that all the good properties of balanced truncation also hold for extended balanced truncation. It turns out that extended balanced truncation is especially useful when there are additional structure constraints in the model to be reduced. This is useful in frequency-weighted reduction, for example. Model reduction is about systematic simplification of com- plex models. This is a topic that has received a great deal of interest at least since the early 1980's, but still hard problems remain to be solved. In particular, most available methods that are guaranteed to deliver good approximations only apply to linear systems, and these methods are usually not structure preserving. In this paper, we propose an extension to balanced truncation that increases the chance of preserving structures.","Title: Estimation over heterogeneous sensor networks\nYear: 2008\n\nAbstract: Design trade-offs between estimation perfor- mance, processing delay and communication cost for a sensor scheduling problem is discussed. We consider a heterogeneous sensor network with two types of sensors: the first type has low-quality measurements, small processing delay and a light communication cost, while the second type is of high quality, but imposes a large processing delay and a high communication cost. Such a heterogeneous sensor network is common in applications, where for instance in a localization system the poor sensor can be an ultrasound sensor while the more powerful sensor can be a camera. Using a time-periodic Kalman filter, we show how one can find an optimal schedule of the sensor communication. One can significantly improve estimation quality by only using the expensive sensor rarely. We also demonstrate how simple sensor switching rules based on the Riccati equation drives the filter into a stable time-periodic Kalman filter. I. INTRODUCTION","Title: Cascade structural model approximation of identified state space models\nYear: 2008\n\nAbstract: General black-box system identification tech- niques such as subspace system identification and FIR/ARX least squares system identification are commonly used to identify multi-input multi-output models from experimental data. However, in many applications there are a priori given structural information. Here the focus is on linear dynamical systems with a cascade structure, and with one input signal and two output signals. Models of such systems are important in e.g. cascade control applications. It is possible to incorporate such a structure in a prediction error method, which, however, is based on rather advanced numerical non-convex optimization techniques to calculate the corresponding structured model estimate. We will instead study how to use model approximation techniques to approximate a general black-box estimate with a structured model. This will avoid the use of numerical optimization and works well with e.g. subspace system identifi- cation, which is a standard method in process industry where cascade systems are very common. The problems of cascade structural model approximation and model reduction are rather non-standard, and we will study several new methods. The basic idea is to first find a higher order but structured model approximation using standard H∞ model matching techniques, and then in a second step use so-called structured balanced model reduction to find lower order structured approximation. Structured balanced model reduction is a rather new approach, with powerful model order selection tools and error bound results. The results of the corresponding two step model approximation approach seem promising, as illustrated by a simple numerical example. I. INTRODUCTION","Title: Steady state performance analysis of multiple state-based schedulers with CSMA\nYear: 2011\n\nAbstract: In this paper, we analyze the performance of multiple event-based systems that share access to the same network. Transmissions are attempted only when a local state-based scheduler generates an event, and access to the network is determined using a Carrier Sensing Multiple Access (CSMA) protocol. In general, the interactions in such a multiple access network introduce correlations between the system variables of the various loops, and the respective traffic contributions as well. Hence, analyzing the performance of this network is difficult. However, a class of state-based schedulers, introduced in the paper, permits a joint analysis of the scheduler and the Contention Resolution Mechanism (CRM). The analysis is based on a Markov model, which is validated through simulations. The resulting steady-state model makes it possible to characterize the statistics of packet arrivals in this network.","Title: Dynamical system decomposition using dissipation inequalities\nYear: 2011\n\nAbstract: In this paper we investigate stability and interaction measures for interconnected systems that have been produced by decomposing a large-scale linear system into a set of lower order subsystems connected in feedback. We begin by analyzing the requirements for asymptotic stability through generalized dissipation inequalities and storage functions. Using this insight we then describe various metrics based on a system's energy dissipation to determine how strongly the subsystems interact with each other. From these metrics a decomposition algorithm is described.","Title: Distributed Fault Detection and Isolation with imprecise network models\nYear: 2012\n\nAbstract: In this paper we consider the problem of Distributed Fault Detection and Isolation (D-FDI) in large networked systems with imprecise models. Taking a previously proposed D-FDI scheme for a given initial network model, we analyze its performance under small changes in the network graph, namely the addition or removal of edges. Under some assumptions, it is shown that for this kind of perturbations there exist suitable thresholds for which fault detection and isolation is achieved. As our second contribution, we propose solutions to accomplish D-FDI with considerably lower computational burden, while handling imprecise network models. Numerical experiments demonstrating the effectiveness of the proposed solution are presented, taking the IEEE 118 bus power network as an example.","Title: Distributed integral action: Stability analysis and frequency control of power systems\nYear: 2012\n\nAbstract: This paper analyzes distributed proportional-integral controllers. We prove that integral action can be successfully applied to consensus algorithms, where attenuation of static disturbances is achieved. These control algorithms are applied to decentralized frequency control of electrical power systems. We show that the proposed algorithm can attenuate step disturbances of power loads. We provide simulations of the proposed control algorithm on the IEEE 30 bus test system that demonstrate its efficiency.","Title: On subspace identification of cascade structured systems\nYear: 2010\n\nAbstract: In identification it is important to take a priori structural information into account in many applications, something that is difficult when using subspace methods. Here will study how to incorporate a special structure, a cascade structure with two subsystems. Two new methods are derived for estimating system with this structure. The problem when using subspace identification on cascade structured system is that the states from the first subsystem are mixed with states from the second subsystem via a unknown similarity transform. The first indirect method finds a similarity transform that takes the system back to a form such that the subsystems can be recovered. The second method uses the fact that the structure of the extended observability matrix is known for cascade systems. However, it only works when both subsystems have order one. In practice this is still a common case. The results of the two methods seem promising, as illustrated by applying the methods to a real process, the double tank process. The performance is comparable with state of the art methods. Finally the problem of optimal input design for cascade systems are introduced, and illustrated by a simple example.","Title: Towards a thermodynamics of control: Entropy, energy and Kalman filtering\nYear: 2013\n\nAbstract: We propose a method to analyse the flows of information and energy between two systems (plant and controller) connected in feedback. Extending a work by Touchette and Lloyd (2000, 2004), we estimate the advantage, both in terms of entropy reduction and energy extraction, of a feedback controller over an open-loop control in terms of the information on the plant state that is available to the controller. By energy here we mean any objective function that we seek to minimize, for example the square of the state. We apply this methodology on the Kalman filter, and develop a physical interpretation comparable to Mitter and Newton's (2005).","Title: Reduced-order predictive outage compensators for networked systems\nYear: 2009\n\nAbstract: Control systems utilizing wireless sensor and ac- tuator networks can be severely affected by the properties of the wireless links. Radio fading and interference may cause communication outage of several samples in situations when the radio environment is noisy and low transmission power is desirable. We propose a method to compensate for outages by introducing a predictive outage compensator (POC), which is a filter to be implemented at the receiver sides of networked control systems and that generates artificial samples during the outage. The main contribution of the paper is to show that a POC can be derived based on a Kalman filter formulation and that it is possible to achieve good performance with a low- order implementation based on Hankel norm approximation. Tradeoffs between achievable closed-loop performance, outage length, and POC order are discussed. The results are illustrated on a simulated example of a multiple-tank process.","Title: Network structure preserving model reduction with weak a priori structural information\nYear: 2009\n\nAbstract: This paper extends a state projection method for structure preserving model reduction to situations where only a weaker notion of system structure is available. This weaker notion of structure, identifying the causal relationship between manifest variables of the system, is especially relevant is settings such as systems biology, where a clear partition of state variables into distinct subsystems may be unknown, or not even exist. The resulting technique, like similar approaches, does not provide theoretical performance guarantees, so an extensive computational study is conducted, and it is observed to work fairly well in practice. Moreover, conditions characterizing structurally minimal realizations and sufficient conditions characterizing edge loss resulting from the reduction process, are presented.","Title: Parameterized model order reduction using extended balanced truncation\nYear: 2012\n\nAbstract: We show how extended balanced truncation can be applied to the parameterized model order reduction (PMOR) problem. Two variants are introduced and are shown to improve already available a priori error bounds, as well as actual approximation errors in a numerical experiment.","Title: Voltage control for interconnected microgrids under adversarial actions\nYear: 2015\n\nAbstract: In this paper, we study the impact of adversarial actions on voltage control schemes in interconnected microgrids. Each microgrid is abstracted as a power inverter that can be controlled to regulate its voltage magnitude and phase-angle independently. Moreover, each power inverter is modeled as a single integrator, whose input is given by a voltage droop-control policy that is computed based on voltage magnitude and reactive power injection measurements. Under mild assumptions, we then establish important properties of the nominal linearized closed-loop system, such as stability, positivity, and diagonal dominance. These properties play an important role when characterizing the potential impact of different attack scenarios. In particular, we discuss two attack scenarios where the adversary corrupts measurement data and reference signals received by the voltage droop controllers. The potential impact of instances of each scenario is analyzed using control-theoretic tools, which may be used to develop methodologies for identifying high-risk attack scenarios, as is illustrated by numerical examples.","Title: Robust Scheduling of Smart Appliances in Active Apartments With User Behavior Uncertainty\nYear: 2016\n\nAbstract: In this paper, we propose a robust approach for scheduling of smart appliances and electrical energy storages (EESs) in active apartments with the aim of reducing both the electricity bill and the $hbox{CO}_{2}$ emissions. The proposed robust formulation takes the user behavior uncertainty into account so that the optimal appliances schedule is less sensitive to unpredictable changes in user preferences. The user behavior uncertainty is modeled as uncertainty in the cost function coefficients. In order to reduce the level of conservativeness of the robust solution, we introduce a parameter allowing to achieve a trade-off between the price of robustness and the protection against uncertainty. Mathematically, the robust scheduling problem is posed as a multi-objective Mixed Integer Linear Programming (MILP), which is solved by using standard algorithms. The numerical results show effectiveness of the proposed approach to increase both the electricity bill and $hbox{CO}_{2}$ emissions savings, in the presence of user behavior uncertainties. Mathematical insights into the robust formulation are illustrated and the sensitivity of the optimum cost in the presence of uncertainties is investigated. Although home appliances and EESs are considered in this work, we point out that the proposed scheduling framework is generally applicable to many use cases, e.g., charging and discharging of electrical vehicles in an effective way. In addition, it is applicable to various scenarios considering different uncertainty sources, different storage technologies and generic programmable electrical loads, as well as different optimization criteria.","Title: Online fault diagnosis for nonlinear power systems\nYear: 2015\n\nAbstract: This paper considers the problem of automatic fault diagnosis for transmission lines in large scale power networks. Since faults in transmission lines threatens stability of the entire power network, fast and reliable fault diagnosis is an important problem in transmission line protection. This work is the first paper exploiting sparse signal recovery for the fault-diagnosis problem in power networks with nonlinear swing-type dynamics. It presents a novel and scalable technique to detect, isolate and identify transmission faults using a relatively small number of observations by exploiting the sparse nature of the faults. Buses in power networks are typically described by second-order nonlinear swing equations. Based on this description, the problem of fault diagnosis for transmission lines is formulated as a compressive sensing or sparse signal recovery problem, which is then solved using a sparse Bayesian formulation. An iterative reweighted ¿ 1 -minimisation algorithm based on the sparse Bayesian learning update is then derived to solve the fault diagnosis problem efficiently. With the proposed framework, a real-time fault monitoring scheme can be built using only measurements of phase angles at the buses.","Title: Distributed Design Of Locally Stabilizing Controllers For Large-Scale Networked Linear Systems\nYear: 2015\n\nAbstract: In this paper, we consider designing locally stabilizing controllers, each of which stabilizes each disconnected subsystem, in a distributed manner for large-scale networked linear systems. To this end, we design a low-dimensional hierarchical distributed compensator such that the L-2-performance of the closed-loop system improves as long as that of the locally stabilizing controllers improves. We solve a controller reduction problem where the approximation error of the low-dimensional compensator gets better as long as the performance of the locally stabilizing controllers improves, while preserving the hierarchical distributed structure of the original compensator. Finally, we demonstrate the efficiency of the proposed method through a numerical example of a power network.","Title: Strategic stealthy attacks: The output-to-output ℓ2-gain.\nYear: 2015\n\nAbstract: In this paper, we characterize and analyze the set of strategic stealthy false-data injection attacks on discrete-time linear systems. In particular, the threat scenarios tackled in the paper consider adversaries that aim at deteriorating the systemu0027s performance by maximizing the corresponding quadratic cost function, while remaining stealthy with respect to anomaly detectors. As opposed to other work in the literature, the effect of the adversaryu0027s actions on the anomaly detectoru0027s output is not constrained to be zero at all times. Moreover, scenarios where the adversary has uncertain model knowledge are also addressed. The set of strategic attack policies is formulated as a non-convex constrained optimization problem, leading to a sensitivity metric denoted as the output-to-output l2-gain. Using the framework of dissipative systems, the output-to-output gain is computed through an equivalent convex optimization problem. Additionally, we derive necessary and sufficient conditions for the output-to-output gain to be unbounded, with and without model uncertainties, which are tightly related to the invariant zeros of the system.","Title: From control system security indices to attack identifiability\nYear: 2016\n\nAbstract: In this paper, we investigate detectability and identifiability of attacks on linear dynamical systems that are subjected to external disturbances. We generalize a concept for a security index, which was previously introduced for static systems. The index exactly quantifies the resources necessary for targeted attacks to be undetectable and unidentifiable in the presence of disturbances. This information is useful for both risk assessment and for the design of anomaly detectors. Finally, we show how techniques from the fault detection literature can be used to decouple disturbances and to identify attacks, under certain sparsity constraints.","Title: Cyber-Physical-Security Framework for Building Energy Management System.\nYear: 2016\n\nAbstract: Energy management systems (EMS) are used to control energy usage in buildings and campuses, by employing technologies such as supervisory control and data acquisition (SCADA) and building management systems (BMS), in order to provide reliable energy supply and maximise user comfort while minimising energy usage. Historically, EMS systems were installed when potential security threats were only physical. Nowadays, EMS systems are connected to the building network and as a result directly to the outside world. This extends the attack surface to potential sophisticated cyber-attacks, which adversely impact EMS operation, resulting in service interruption and downstream financial implications. Currently, the security systems that detect attacks operate independently to those which deploy resiliency policies and use very basic methods. We propose a novel EMS cyber-physical-security framework that executes a resilient policy whenever an attack is detected using security analytics. In this framework, both the resilient policy and the security analytics are driven by EMS data, where the physical correlations between the data-points are identified to detect outliers and then the control loop is closed using an estimated value in place of the outlier. The framework has been tested using a reduced order model of a real EMS site.","Title: Clustering-Based Model Reduction of Networked Passive Systems.\nYear: 2016\n\nAbstract: The model reduction problem for networks of interconnected dynamical systems is studied in this paper. In particular, networks of identical passive subsystems, which are coupled according to a tree topology, are considered. For such networked systems, reduction is performed by clustering subsystems that show similar behavior and subsequently aggregating their states, leading to a reduced-order networked system that allows for an insightful physical interpretation. The clusters are chosen on the basis of the analysis of controllability and observability properties of associated edge systems, representing the importance of the couplings and providing a measure of the similarity of the behavior of neighboring subsystems. This reduction procedure is shown to preserve synchronization properties (i.e., the convergence of the subsystem trajectories to each other) and allows for the a priori computation of a bound on the reduction error with respect to external inputs and outputs. The method is illustrated by means of an example of a thermal model of a building.","Title: Optimal State Estimation With Measurements Corrupted By Laplace Noise\nYear: 2016\n\nAbstract: Optimal state estimation for linear discrete-time systems is considered. Motivated by the literature on differential privacy, the measurements are assumed to be corrupted by Laplace noise. The optimal least mean square error estimate of the state is approximated using a randomized method. The method relies on that the Laplace noise can be rewritten as Gaussian noise scaled by Rayleigh random variable. The probability of the event that the distance between the approximation and the best estimate is smaller than a constant is determined as function of the number of parallel Kalman filters that is used in the randomized method. This estimator is then compared with the optimal linear estimator, the maximum a posteriori (MAP) estimate of the state, and the particle filter.","Title: Limiting the Impact of Stealthy Attacks on Industrial Control Systems.\nYear: 2016\n\nAbstract: While attacks on information systems have for most practical purposes binary outcomes (information was manipulated/eavesdropped, or not), attacks manipulating the sensor or control signals of Industrial Control Systems (ICS) can be tuned by the attacker to cause a continuous spectrum in damages. Attackers that want to remain undetected can attempt to hide their manipulation of the system by following closely the expected behavior of the system, while injecting just enough false information at each time step to achieve their goals. In this work, we study if attack-detection can limit the impact of such stealthy attacks. We start with a comprehensive review of related work on attack detection schemes in the security and control systems community. We then show that many of those works use detection schemes that are not limiting the impact of stealthy attacks. We propose a new metric to measure the impact of stealthy attacks and how they relate to our selection on an upper bound on false alarms. We finally show that the impact of such attacks can be mitigated in several cases by the proper combination and configuration of detection schemes. We demonstrate the effectiveness of our algorithms through simulations and experiments using real ICS testbeds and real ICS systems.","Title: Distributed Design of Distributed Control Systems: A Compensation Principle for Controller Retrofit.\nYear: 2016\n\nAbstract: This paper develops a distributed design method for distributed control systems using hierarchical state-space expansion. This expansion generates a redundant state-space realization of systems that enables to regard the system state as the superposition of cascade system states. It is shown from the fact that the stabilization problem of cascade systems can be divided into the stabilization of certain so called upstream and downstream subsystems. This paper clarifies that a downstream subsystem controller can be regarded as a preexistent controller that has implemented to ensure the system stability, whereas a upstream subsystem controller can be regarded as a retrofit controller given as an additional controller with a dynamical compensator. To demonstrate the significance of the proposed distributed design, we give two application examples: one on distributed control of a power system and one on distributed control of a vehicle platoon. The examples demonstrate that appropriate determination of parameter matrices in the hierarchical state- space expansion has some practical relevance for distributed design. Numerical simulations on these examples are shown to support the effectiveness of the theoretical developments.","Title: D-Stability And Delay-Independent Stability Of Monotone Nonlinear Systems With Max-Separable Lyapunov Functions\nYear: 2016\n\nAbstract: Stability properties of monotone nonlinear systems with max-separable Lyapunov functions are considered in this paper, motivated by the following observations. First, recent results have shown that such Lyapunov functions are guaranteed to exist for asymptotically stable monotone systems on compact sets. Second, it is well-known that, for monotone linear systems, asymptotic stability implies the stronger properties of D-stability and robustness with respect to time-delays. This paper shows that similar properties hold for monotone nonlinear systems that admit max-separable Lyapunov functions. In particular, a notion of D-stability for monotone nonlinear systems and delay-independent stability will be discussed. The theoretical results are illustrated by means of examples.","Title: Secure Estimation For Unstable Systems\nYear: 2016\n\nAbstract: We assume that the states of an unstable dynamical system are encoded and sent to an estimator through an uncertain channel, which is a channel disturbing its inputs in a nonstochastic manner. The encoder's codeword is also fed into another uncertain channel, at whose output an eavesdropper is listening. The estimator should obtain a uniformly bounded system state estimation error, whereas the eavesdropper's information about the system states should be subject to a security constraint. We find a condition on the relation between the uncertain channel from encoder to estimator and the uncertain channel from encoder to eavesdropper which if satisfied allows for at least one of the two following security criteria to hold: The volume of the set of states possible acccording to the eavesdropper's information tends to infinity at exponential speed-by itself (strong security) or if divided by the volume of the set of states possible according to the estimator's information (weak security).","Title: Directed Information as Privacy Measure in Cloud-based Control.\nYear: 2017\n\nAbstract: We consider cloud-based control scenarios in which clients with local control tasks outsource their computational or physical duties to a cloud service provider. In order to address concerns in such a control architecture, we first investigate the issue of finding an appropriate measure for clients who desire to keep local state information as private as possible during the control operation. Specifically, we justify the use of Krameru0027s notion of causally conditioned directed information as a measure of loss based on an axiomatic argument. Then we propose a methodology to design an optimal privacy that minimizes loss while a given level of control performance is guaranteed. We show in particular that the optimal filter for cloud-based Linear-Quadratic-Gaussian (LQG) control can be synthesized by a Linear-Matrix-Inequality (LMI) algorithm. The trade-off in the design is illustrated by a numerical example.","Title: On the Coherence of Large-Scale Networks With Distributed PI and PD Control.\nYear: 2017\n\nAbstract: We consider distributed control of double-integrator networks, where agents are subject to stochastic disturbances. We study performance of such networks in terms of coherence, defined through an '1i2 norm metric that represents the variance of nodal state fluctuations. Specifically, we address known performance limitations of the standard consensus protocol, which cause this variance to scale unb...","Title: Performance And Scalability Of Voltage Controllers In Multi-Terminal Hvdc Networks\nYear: 2017\n\nAbstract: In this paper, we compare the transient performance of a multi-terminal high-voltage DC (MTDC) grid equipped with a slack bus for voltage control to that of two distributed control schemes: a standard droop controller and a distributed averaging proportional-integral (DAPI) controller. We evaluate performance in terms of an H-2 metric that quantifies expected deviations from nominal voltages, and show that the transient performance of a droop or DAPI controlled MTDC grid is always superior to that of an MTDC grid with a slack bus. In particular, by studying systems built up over lattice networks, we show that the H-2 norm of a slack bus controlled system may scale unboundedly with network size, while the norm remains uniformly bounded with droop or DAPI control. We simulate the control strategies on radial MTDC networks to demonstrate that the transient performance for the slack bus controlled system deteriorates significantly as the network grows, which is not the case with the distributed control strategies.","Title: Directed Information And Privacy Loss In Cloud-Based Control\nYear: 2017\n\nAbstract: We consider a cloud-based control framework in which individual clients own their local plants that must be controlled by a public authority. Individual clients desire to keep the local state information as private as possible, as long as the cloud-based controller can provide a given level of quality of service. Based on an axiomatic argument, we show that Kramer's notion of causally conditioned directed information from the state random variable to a random variable disclosed to the public authority is an appropriate measure of privacy loss. For a special case with the Linear-Quadratic-Gaussian (LQG) setting, we provide a procedure to construct a \"privacy filter\" that attains the optimal trade-off between privacy loss and control quality.","Title: Guest Editorial Distributed Control and Efficient Optimization Methods for Smart Grid.\nYear: 2017\n\nAbstract: Smart grid proactively uses the state-of-the-art technologies in communications, computing, and control to improve efficiency, reliability, sustainability, and stability of the electrical grid. In particular, distribution networks are expected to undergo dramatic changes by incorporating a large number of sensors and thousands of controllable devices such as distributed generators, batteries and f...","Title: A Survey of Distributed Optimization and Control Algorithms for Electric Power Systems.\nYear: 2017\n\nAbstract: Historically, centrally computed algorithms have been the primary means of power system optimization and control. With increasing penetrations of distributed energy resources requiring optimization and control of power systems with many controllable devices, distributed algorithms have been the subject of significant research interest. This paper surveys the literature of distributed algorithms wi...","Title: The interconnection of quadratic droop voltage controllers is a Lotka-Volterra system: implications for stability analysis.\nYear: 2018\n\nAbstract: This letter studies the stability of voltage dynamics for a power network in which nodal voltages are controlled by means of quadratic droop controllers with nonlinear AC reactive power as inputs. We show that the voltage dynamics is a Lotka-Volterra system, which is a class of nonlinear positive systems. We study the stability of the closed-loop system by proving a uniform ultimate boundedness re...","Title: Exploiting Submodularity in Security Measure Allocation for Industrial Control Systems.\nYear: 2017\n\nAbstract: Industrial control systems are cyber-physical systems that are used to operate critical infrastructures such as smart grids, traffic systems, industrial facilities, and water distribution networks. The digitalization of these systems increases their efficiency and decreases their cost of operation, but also makes them more vulnerable to cyber-attacks. In order to protect industrial control systems from cyber-attacks, the installation of multiple layers of security measures is necessary. In this paper, we study how to allocate a large number of security measures under a limited budget, such as to minimize the total risk of cyber-attacks. The security measure allocation problem formulated in this way is a combinatorial optimization problem subject to a knapsack (budget) constraint. The formulated problem is NP-hard, therefore we propose a method to exploit submodularity of the objective function so that polynomial time algorithms can be applied to obtain solutions with guaranteed approximation bounds. The problem formulation requires a preprocessing step in which attack scenarios are selected, and impacts and likelihoods of these scenarios are estimated. We discuss how the proposed method can be applied in practice.","Title: Coherence In Synchronizing Power Networks With Distributed Integral Control\nYear: 2017\n\nAbstract: We consider frequency control of synchronous generator networks and study transient performance under both primary and secondary frequency control. We model random step changes in power loads and evaluate performance in terms of expected deviations from a synchronous frequency over the synchronization transient; what can be thought of as lack of frequency coherence. We compare a standard droop control strategy to two secondary proportional integral (PI) controllers: centralized averaging PI control (CAPI) and distributed averaging PI control (DAPI). We show that the performance of a power system with DAPI control is always superior to that of a CAPI controlled system, which in turn has the same transient performance as standard droop control. Furthermore, for a large class of network graphs, performance scales unfavorably with network size with CAPI and droop control, which is not the case with DAPI control. We discuss optimal tuning of the DAPI controller and describe how internodal alignment of the integral states affects performance. Our results are demonstrated through simulations of the Nordic power grid.","Title: Optimal Privacy-Preserving Policy Using Constrained Additive Noise To Minimize The Fisher Information\nYear: 2017\n\nAbstract: The problem of preserving the privacy of individual entries of a database with constrained additive noise is considered. An adversary can submit linear queries to an agent possessing the entire database. The agent returns a response to the query that is corrupted by an additive random noise whose support is a subset or equal to a constraint set. The Cramer-Rao bound is used to bound the variance of the estimation error of the database, which may be used by the adversary, to the trace of the inverse of the Fisher information matrix. A measure of privacy using the Fisher information matrix is developed. The probability density that minimizes the Fisher information (as a proxy for maximizing the measure of privacy) is computed.","Title: Glocal Control For Network Systems Via Hierarchical State-Space Expansion\nYear: 2017\n\nAbstract: In this paper, we propose a glocal (global/local) control method for large-scale network systems. The objective of the glocal control here is to suppress global propagation of a disturbance injected at a local subsystem based on the integration of different types of controllers, called global and local controllers. For the design of global and local controllers, we construct an aggregated model and a truncated model that can, respectively, capture global average behavior and local subsystem behavior of the network system of interest. Based on state-space expansion, called hierarchical state-space expansion, we show that a cascade interconnection of the aggregated model and the truncated model can be seen as a low-dimensional approximate model of the original network system, which has good compatibility with independent design of the global and local controllers. Furthermore, we show that appropriate integration of the global and local controllers can improve control performance with respect to global propagation of local disturbance. Finally, the effectiveness of the proposed method is shown through a numerical example of a benchmark model representing the bulk power system in the eastern half of Japan.","Title: Wireless Sensor Network Scheduling For Remote Estimation Under Energy Constraints\nYear: 2017\n\nAbstract: This paper studies a design problem of how a group of wireless sensors are selected and scheduled to transmit data efficiently over a multi-hop network subject to energy-saving consideration, when they are observing multiple independent discrete-time linear systems. Each time instant, some sensors are selected to transmit their measurements to a remote estimator. We formulate an optimization problem, minimizing a linear combination of the averaged estimation error and the averaged transmission energy consumption to obtain suitable network scheduling and estimation algorithms. Necessary conditions for optimality are derived and these conditions help trim the feasible solution space so that the optimal solution can be computed efficiently. A numerical example is provided to demonstrate the theoretical results.","Title: A Framework for Attack-Resilient Industrial Control Systems: Attack Detection and Controller Reconfiguration.\nYear: 2018\n\nAbstract: Most existing industrial control systems (ICSs), such as building energy management systems (EMSs), were installed when potential security threats were only physical. With advances in connectivity, ICSs are now, typically, connected to communications networks and, as a result, can be accessed remotely. This extends the attack surface to include the potential for sophisticated cyber attacks, which ...","Title: A Security Index for Actuators Based on Perfect Undetectability: Properties and Approximation.\nYear: 2018\n\nAbstract: A novel security index based on the definition of perfect undetectability is proposed. The index is a tool that can help a control system operator to localize the most vulnerable actuators in the network. In particular, the security index of actuator i represents the minimal number of sensors and actuators that needs to be compromised in addition to i, such that a perfectly undetectable attack is possible. A method for computing this index for small scale systems is derived, and difficulties with the index once the system is of large scale are outlined. An upper bound for the index that overcomes these difficulties is then proposed. The theoretical developments are illustrated on a numerical example.","Title: Anomaly Detector Metrics for Sensor Data Attacks in Control Systems\nYear: 2018\n\nAbstract: We investigate worst-case impacts of stealthy full sensor attacks against linear control systems under a general class of anomaly detectors. We show that the worst-case impact scales with a parameter that is solely determined by the number of sensors in the plant, the detector used, and its tuning. Therefore, we obtain a general metric to compare the performance of detectors of this class of detectors under the investigated sensor attack, which is independent of the plant dynamics and applies to all linear systems with the same number of sensors.","Title: Optimization Of The H-Infinity-Norm Of Dynamic Flow Networks\nYear: 2018\n\nAbstract: In this paper, we study the H-infinity-norm of linear systems over graphs, which is used to model distribution networks. In particular, we aim to minimize the H-infinity-norm subject to allocation of the weights on the edges. The optimization problem is formulated with LMI (Linear-Matrix Inequality) constraints. For distribution networks with one port, i.e., SISO systems, we show that the H-infinity-norm coincides with the effective resistance between the nodes in the port. Moreover, we derive an upper bound of the H-infinity-norm, which is in terms of the algebraic connectivity of the graph on which the distribution network is defined.","Title: Performance Limitations Of Distributed Integral Control In Power Networks Under Noisy Measurements\nYear: 2018\n\nAbstract: Distributed approaches to secondary frequency control have become a way to address the need for more flexible control schemes in power networks with increasingly distributed generation. The distributed averaging proportional-integral (DAPI) controller presents one such approach. In this paper, we analyze the transient performance of this controller, and specifically address the question of its performance under noisy frequency measurements. Performance is analyzed in terms of an H-2 norm metric that quantifies power losses incurred in the synchronization transient. While previous studies have shown that the DAPI controller performs well, in particular in sparse networks and compared to a centralized averaging PI (CAPI) controller, our results prove that additive measurement noise may have a significant negative impact on its performance and scalability. This impact is shown to decrease with an increased inter-nodal alignment of the controllers' integral states, either through increased gains or increased connectivity. For very large and sparse networks, however, the requirement for inter-nodal alignment is so large that a CAPI approach may be preferable. Overall, our results show that distributed secondary frequency control through DAPI is possible and may perform well also under noisy measurements, but requires careful tuning.","Title: Retrofit control: Localization of controller design and implementation.\nYear: 2018\n\nAbstract: In this paper, we propose a retrofit control method for stable network systems. The proposed approach is a control method that, rather than an entire system model, requires a model of the subsystem of interest for controller design. To design the retrofit controller, we use a novel approach based on hierarchical state-space expansion that generates a higher-dimensional cascade realization of a given network system. The upstream dynamics of the cascade realization corresponds to an isolated model of the subsystem of interest, which is stabilized by a local controller. The downstream dynamics can be seen as a dynamical model representing the propagation of interference signals among subsystems, the stability of which is equivalent to that of the original system. This cascade structure enables a systematic analysis of both the stability and control performance of the resultant closed-loop system. The resultant retrofit controller is formed as a cascade interconnection of the local controller and an output rectifier that rectifies an output signal of the subsystem of interest so as to conform to an output signal of the isolated subsystem model while acquiring complementary signals neglected in the local controller design, such as interconnection signals from neighboring subsystems. Finally, the efficiency of the retrofit control method is demonstrated through numerical examples of power systems control and vehicle platoon control.","Title: A Survey of Physics-Based Attack Detection in Cyber-Physical Systems.\nYear: 2018\n\nAbstract: Monitoring the \"physics\" of cyber-physical systems to detect attacks is a growing area of research. In its basic form a security monitor creates time-series models of sensor readings for an industrial control system and identifies anomalies in these measurements in order to identify potentially false control commands or false sensor readings. In this paper, we review previous work on physics-based anomaly detection based on a unified taxonomy that allows us to identify limitations and unexplored challenges, and propose new solutions.","Title: Ensuring Privacy with Constrained Additive Noise by Minimizing Fisher Information.\nYear: 2019\n\nAbstract: The problem of preserving the privacy of individual entries of a database when responding to linear or nonlinear queries with constrained additive noise is considered. For privacy protection, the response to the query is systematically corrupted with an additive random noise whose support is a subset or equal to a pre-defined constraint set. A measure of privacy using the inverse of the trace of the Fisher information matrix is developed. The Cramér–Rao bound relates the variance of any estimator of the database entries to the introduced privacy measure. The probability density that minimizes the trace of the Fisher information (as a proxy for maximizing the measure of privacy) is computed. An extension to dynamic problems is also presented. Finally, the results are compared to the differential privacy methodology.","Title: Synchronization Of Kuramoto Oscillators In A Bidirectional Frequency-Dependent Tree Network\nYear: 2018\n\nAbstract: This paper studies the synchronization of a finite number of Kuramoto oscillators in a frequency-dependent bidirectional tree network. We assume that the coupling strength of each link in each direction is equal to the product of a common coefficient and the exogenous frequency of its corresponding source oscillator. We derive a sufficient condition for the common coupling strength in order to guarantee frequency synchronization in tree networks. Moreover, we discuss the dependency of the obtained bound on both the graph structure and the way that exogenous frequencies are distributed. Further, we present an application of the obtained result by means of an event-triggered algorithm for achieving frequency synchronization in a star network assuming that the common coupling coefficient is given.","Title: Large Scale Rollout of Smart Grid Services\nYear: 2018\n\nAbstract: In the domain of energy automation, where a massive number of software-based IoT services interact with a complex dynamic system, processes for software installation and software update become more important and more complex. These processes have to ensure that the dependencies on all layers are fulfilled, including dependencies arising due to the energy system controlled by IT components being a hidden communication channel between these components. In addition, the processes have to be resilient against faults in and attacks to both the energy grid and the communication network. The ERA-Net funded project LarGo! aims at developing and testing processes for the large scale rollout of software applications in the power grid domain as well as the user domain. This article describes a work in progress and the project's roadmap to solve the technical issues. It investigates the problems that arise from the interlocking of the two networks- the power grid and the communication network. Based on this analysis a first set of requirements for a rollout process in such a Smart Grid is derived and the chosen approach to verify the resilience of the developed processes under research is described.","Title: Estimating the Impact of Cyber-Attack Strategies for Stochastic Control Systems.\nYear: 2018\n\nAbstract: Risk assessment is an inevitable step in implementation of a cyber-defense strategy. An important part of this assessment is to reason about the impact of possible attacks. In this paper, we study the problem of estimating the impact of cyber-attacks in stochastic linear networked control systems. For the stealthiness constraint, we adopt the Kullback–Leibler divergence between attacked and nonatt...","Title: Quantifying the Impact of Cyber-Attack Strategies for Control Systems Equipped With an Anomaly Detector\nYear: 2018\n\nAbstract: Risk assessment is an inevitable step in the implementation of cost-effective security strategies for control systems. One of the difficulties of risk assessment is to estimate the impact cyber-attacks may have. This paper proposes a framework to estimate the impact of several cyber-attack strategies against a dynamical control system equipped with an anomaly detector. In particular, we consider denial of service, sign alternation, rerouting, replay, false data injection, and bias injection attack strategies. The anomaly detectors we consider are stateless, cumulative sum, and multivariate exponentially weighted moving average detectors. As a measure of the attack impact, we adopt the infinity norm of critical states after a fixed number of time steps. For this measure and the aforementioned anomaly detectors, we prove that the attack impact for all of the attack strategies can be reduced to the problem of solving a set of convex minimization problems. Therefore, the exact value of the attack impact can be obtained easily. We demonstrate how our modeling framework can be used for risk assessment on a numerical example.","Title: Asymptotic And Finite-Time Almost Global Attitude Tracking: Representations Free Approach\nYear: 2018\n\nAbstract: In this paper, the attitude tracking problem is considered using the rotation matrices. Due to the inherent topological restriction, it is impossible to achieve global attractivity with any continuous attitude control system on SO(3). Hence in this work, we propose some control protocols achieving almost global tracking asymptotically and in finite time, respectively. In these protocols, no world frame is needed and only relative state information are requested. For finite-time tracking case, Filippov solutions and non-smooth analysis techniques are adopted to handle the discontinuities. Simulation examples are provided to verify the performances of the control protocols designed in this paper.","Title: Secure Patching Of An Output-Feedback Controller For A Class Of Nonlinear Systems Under Adversarial Attack\nYear: 2018\n\nAbstract: We consider a class of nonlinear systems for which an observer-based output-feedback controller is updated at discrete time instances. However, the received update or patch can be compromised by the attacker to drive the system to instability. In this paper, we provide a checkable condition to ensure that the received patch has not been tampered with to cause instability in the control system. Moreover, we guarantee that the application of the tamper-free patch ensures global asymptotic stability of the control system by choosing the update time instances appropriately. The secure patch update protocol is illustrated on an example involving the output-feedback synchronization of two neuron population models, where the observer gains are updated at discrete time instances.","Title: A Risk-Theoretical Approach To H-2-Optimal Control Under Covert Attacks\nYear: 2018\n\nAbstract: We consider the control design problem of optimizing the H-2 performance of a closed-loop system despite the presence of a malicious covert attacker. It is assumed that the attacker has incomplete knowledge on the true process we are controlling. To account for this uncertainty, we employ different measures of risk from the so called family of coherent measures of risk. In particular, we compare the closed-loop performance when a nominal value is used, with three different measures of risk: average risk, worst-case scenario and conditional valueat- risk (CVaR). Additionally, applying the approach from a previous work, we derive a convex formulation for the control design problem when CVaR is employed to quantify the risk. A numerical example illustrates the advantages of our approach.","Title: A Game-Theoretic Approach For Choosing A Detector Tuning Under Stealthy Sensor Data Attacks\nYear: 2018\n\nAbstract: A Stackelberg game framework is presented to choose the detector tuning for a general detector class under stealthy sensor attacks. In this framework, the defender acts as a leader and chooses a detector tuning, while the attacker will follow with a stealthy attack adjusted to this tuning. The tuning chosen is optimal with respect to the cost induced by the false alarms and the attack impact. We can show that under some practical assumptions the Stackelberg game always has a solution and we state two different sufficient conditions for the uniqueness of the solution. Interestingly, these conditions show that the attack impact does not have to be a convex function. An illustrative attack scenario of a false-data injection attack shows how one can use the Stackelberg game to find the optimal detector tuning.","Title: Two-Way Coding in Control Systems Under Injection Attacks: From Attack Detection to Attack Correction.\nYear: 2019\n\nAbstract: In this paper, we introduce the method of two-way coding, a concept originating in communication theory characterizing coding schemes for two-way channels, into (networked) feedback control systems under injection attacks. We first show that the presence of two-way coding can distort the perspective of the attacker on the control system. In general, the distorted viewpoint on the attacker side as a consequence of two-way coding will facilitate detecting the attacks, or restricting what the attacker can do, or even correcting the attack effect. In the particular case of zero-dynamics attacks, if the attacks are to be designed according to the original plant, then they will be easily detected; while if the attacks are designed with respect to the equivalent plant as viewed by the attacker, then under the additional assumption that the plant is stabilizable by static output feedback, the attack effect may be corrected in steady state.","Title: A Study On The Sensitivity Matrix In Power System State Estimation By Using Sparse Principal Component Analysis\nYear: 2016\n\nAbstract: This paper analyzes the joint impact of uncertainties in the input data on the power system state estimator. The approach is based on the sensitivity analysis of the estimated telemetry data with respect to the measurement data and the branch parameters with the main goal of locating relevant input components. In order to find relevant inputs, we analyze the normalized sensitivity matrix by sparse principal component analysis (PCA). The non-zero entries of the loading vectors related to the dominant principal components are considered to be the relevant inputs to the state estimator as they mainly contribute to the amplification of the estimated values. It turns out that PCA shows an elementary structure of the sensitivity matrix: All non-zero entries of a loading vector corresponding to a positive singular value belong either to the telemetry data or to the branch data. We show that this property is also valid for PCA with different sparsity-promoting constraints on the loading vector. The proposed analysis method is demonstrated by a numerical study.","Title: Retrofitting State Feedback Control Of Networked Nonlinear Systems Based On Hierarchical Expansion\nYear: 2016\n\nAbstract: In this paper, we propose a systematic method to design retrofit controllers for networked nonlinear systems. The retrofit controller, which consists of a linear state feedback controller and a dynamical compensator, can improve the control performance for a subsystem of interest, while guaranteeing the stability of the whole closed-loop system. Towards the retrofit controller design, we introduce a type of state-space expansion, called hierarchical expansion. The cascade structure of the hierarchical expansion realization enables the systematic design of a stabilizing controller for a low-dimensional linear model extracted from the subsystem of interest. As a result, we can design a retrofit controller without explicit consideration of the dynamics of subsystems other than the subsystem of interest. The effectiveness of the proposed method is demonstrated through a power network example.","Title: Security Analysis Of Control System Anomaly Detectors\nYear: 2017\n\nAbstract: Two anomaly detectors for control systems are analyzed with respect to their sensitivity to malicious data injection attacks. A stateless anomaly detector based on the current residual signal is compared to a cumulative sum detector. The worst-case impact of a stealthy time-limited data injection attack is characterized for both detectors by a non-convex optimization problem and compared to determine which detector limits the impact the most. We prove that the problem can be solved by means of a set of convex optimization problems. Simulations verify that finding the right configuration for the cumulative sum is crucial to limit the worst-case attack impact more than with a stateless anomaly detector.","Title: Distributed Sensor and Actuator Reconfiguration for Fault-Tolerant Networked Control Systems.\nYear: 2018\n\nAbstract: In this paper, we address the problem of distributed reconfiguration of networked control systems upon the removal of misbehaving sensors and actuators. In particular, we consider systems with redundant sensors and actuators cooperating to recover from faults. Reconfiguration is performed while minimizing a steady-state estimation error covariance and quadratic control cost. A model-matching condi...","Title: Noise-induced limitations to the scalability of distributed integral control\nYear: 2019\n\nAbstract: We study performance limitations of distributed feedback control in large-scale networked dynamical systems. Specifically, we address the question of how the performance of distributed integral control is affected by measurement noise. We consider second-order consensus-like problems modeled over a toric lattice network, and study asymptotic scalings (in network size) of H2 performance metrics that quantify the variance of nodal state fluctuations. While previous studies have shown that distributed integral control fundamentally improves these performance scalings compared to distributed proportional feedback control, our results show that an explicit inclusion of measurement noise leads to the opposite conclusion. The noise’s impact on performance is shown to decrease with an increased inter-nodal alignment of the local integral states. However, even though the controller can be tuned for acceptable performance for any given network size, performance will degrade as the network grows, limiting the scalability of any such controller tuning. In particular, the requirement for inter-nodal alignment increases with network size. We show that this may in practice imply that very large and sparse networks will require any integral control to be centralized, rather than distributed. In this case, the best-achievable performance scaling, which is shown to be that of proportional feedback control, is retrieved.","Title: A Graph-Theoretic Approach to the ℋ Performance of Leader-Follower Consensus on Directed Networks.\nYear: 2019\n\nAbstract: We study a graph-theoretic approach to the H∞ performance of leader following consensus dynamics in the presence of external disturbances when the underlying graph is a directed network. We first provide graph-theoretic necessary and sufficient conditions for the consensus dynamics to have the system H∞ norm from external disturbances to the state of each agent to be lower than a certain value. Mo...","Title: Sample-based anomaly detector tuning with finite sample guarantees\nYear: 2021\n\nAbstract: We present a sample-based approach for tuning an anomaly detector threshold to achieve an acceptable false alarm rate without a priori knowledge of system or detector dynamics. If the distribution of the output of the detector is known, finding such a threshold can be re-interpreted as determining a specific quantile of the detector output distribution, which is the minimizer of a convex optimization problem. The sample-based approach we propose approximates the threshold from the empirical distribution. We, further, identify distribution free finite sample guarantees that give the number of samples required to ensure the false alarm rate is near the acceptable value. Finally, we numerically verify our approach on both static and dynamic anomaly detectors, where we investigate both light- and heavy-tailed distributions.","Title: Resource Constrained Sensor Attacks by Minimizing Fisher Information\nYear: 2021\n\nAbstract: We analyze the impact of sensor attacks on a linear state estimation problem subject to variance and sparsity constraints. We show that the maximum impact in a leader-follower game where the attacker first chooses the distribution of an adversarial perturbation and the defender follows by choosing an estimator is characterized by a minimum Fisher information principle. In general, this is a nonlinear variational problem, but we show that it can be reduced to a finite-dimensional mixed integer SDP. Alternatively, the proposed solution can be seen as a lower bound on the maximum impact for a game in which the defender plays first.","Title: Adversarial Attacks on CFO-Based Continuous Physical Layer Authentication: A Game Theoretic Study\nYear: 2021\n\nAbstract: 5G and beyond 5G low power wireless networks make Internet of Things (IoT) and Cyber-Physical Systems (CPS) applications capable of serving massive amounts of devices and machines. Due to the broadcast nature of wireless networks, it is crucial to secure the communication between these devices and machines from spoofing and interception attacks. This paper is concerned with the security of carrier...","Title: Privacy Guarantees for Cloud-based State Estimation using Partially Homomorphic Encryption\nYear: 2022\n\nAbstract: The privacy aspect of state estimation algorithms has been drawing high research attention due to the necessity for a trustworthy private environment in cyber-physical systems. These systems usually engage cloud-computing platforms to aggregate essential information from spatially distributed nodes and produce desired estimates. The exchange of sensitive data among semi-honest parties raises privacy concerns, especially when there are coalitions between parties. We propose two privacy-preserving protocols using Kalman filter and partially homomorphic encryption of the measurements and estimates while exposing the covariances and other model parameters. We prove that the proposed protocols achieve satisfying computational privacy guarantees against various coalitions based on formal cryptographic definitions of indistinguishability. We evaluate the proposed protocols to demonstrate their efficiency using data from a real testbed.","Title: Control Theory For Practical Cyber-Physical Security\nYear: 2018\n\nAbstract: In this talk, we discuss how control theory can contribute to the analysis and design of secure cyber-physical systems. We start by reviewing conditions for undetectable false-data injection attacks on feedback control systems. In particular, we highlight how a physical understanding of the controlled process can guide us in the allocation of protective measures. We show that protecting only a few carefully selected actuators or sensors can give indirect protection to many more components. We then illustrate how such analysis is exploited in the design of a resilient control scheme for a microgrid energy management system.","Title: Security index based on perfectly undetectable attacks: Graph-theoretic conditions\nYear: 2021\n\nAbstract: The notion of security index quantifies the least effort involved in conducting perfectly undetectable attacks. Thus, the security index enables a systems operator to assess the vulnerability of a component, informs sensor placement strategies, and helps in deciding the feasibility of secure estimators and fault detectors. In this paper, we investigate the (possible) variation in this index as a consequence of variation in the system parameters. To this end, we adopt a structured systems approach, typically represented by a directed graph, with the edges of the said graph being in one-to-one correspondence with the system parameters. We first show that the security index is generic. That is, for almost all choices of edge weights, the security index of a component remains the same. We refer to such an index as the generic security index. Secondly, we derive graph-theoretic conditions (and based on those an algorithm) for computing the generic security index. Third, we provide graph-theoretic conditions for computing lower (resp. upper) bounds on the values that the security index of a component can take for all nonzero choices of the edge weights of the directed graph. Finally, we provide a brute force search method for calculating the said bounds.","Title: A Randomized Filtering Strategy Against Inference Attacks on Active Steering Control Systems\nYear: 2022\n\nAbstract: In this paper, we develop a framework against inference attacks aimed at inferring the values of the controller gains of an active steering control system (ASCS). We first show that an adversary with access to the shared information by a vehicle, via a vehicular ad hoc network (VANET), can reliably infer the values of the controller gains of an ASCS. This vulnerability may expose the driver as wel...","Title: Single Trajectory Nonparametric Learning of Nonlinear Dynamics.\nYear: 2022\n\nAbstract: Given a single trajectory of a dynamical system, we analyze the performance of the nonparametric least squares estimator (LSE). More precisely, we give nonasymptotic expected $l^2$-distance bounds between the LSE and the true regression function, where expectation is evaluated on a fresh, counterfactual, trajectory. We leverage recently developed information-theoretic methods to establish the optimality of the LSE for nonparametric hypotheses classes in terms of supremum norm metric entropy and a subgaussian parameter. Next, we relate this subgaussian parameter to the stability of the underlying process using notions from dynamical systems theory. When combined, these developments lead to rate-optimal error bounds that scale as $T^{-1/(2+q)}$ for suitably stable processes and hypothesis classes with metric entropy growth of order $\\delta^{-q}$. Here, $T$ is the length of the observed trajectory, $\\delta \\in \\mathbb{R}_+$ is the packing granularity and $q\\in (0,2)$ is a complexity term. Finally, we specialize our results to a number of scenarios of practical interest, such as Lipschitz dynamics, generalized linear models, and dynamics described by functions in certain classes of Reproducing Kernel Hilbert Spaces (RKHS).","Title: Leakage Localization in Water Distribution Networks: A Model-Based Approach\nYear: 2022\n\nAbstract: The paper studies the problem of leakage localization in water distribution networks. For the case of a single pipe that suffers from a single leak, by taking recourse to pressure and flow measurements, and assuming those are noiseless, we provide a closed-form expression for leak localization, leak exponent and leak constant. For the aforementioned setting, but with noisy pressure and flow measurements, an expression for estimating the location of the leak is provided. Finally, assuming the existence of a single leak, for a network comprising of more than one pipe and assuming that the network has a tree structure, we provide a systematic procedure for determining the leak location, the leak exponent, and the leak constant.","Title: GEOMETRICAL CHARACTERIZATION OF SENSOR PLACEMENT FOR CONE-INVARIANT AND MULTI-AGENT SYSTEMS AGAINST UNDETECTABLE ZERO-DYNAMICS ATTACKS\\ast\nYear: 2022\n\nAbstract: Undetectable attacks are an important class of malicious attacks threatening the security of cyber-physical systems, which can modify a system's state but leave the system output measurements unaffected and hence cannot be detected from the output. This paper studies undetectable attacks on cone-invariant systems and multi-agent systems. We first provide a general characterization of zero-dynamics attacks, which characterizes fully undetectable attacks targeting the nonminimum phase zeros of a system. This geometrical characterization makes it possible to develop a defense strategy seeking to place a minimal number of sensors to detect and counter the zero-dynamics attacks on the system's actuators. The detect and defense scheme amounts to computing a set containing potentially vulnerable actuator locations and nodes and a defense union for feasible placement of sensors based on the geometrical properties of the cones under consideration.","Title: Data-injection Attacks Using Historical Inputs and Outputs\nYear: 2021\n\nAbstract: Data-driven, model-free control has become popular in recent years, due to their ease of implementation and minimal information requirement about the system. In this paper, we investigate whether the same methods could be used by an adversary to synthesize undetectable data-injection attacks on cyber-physical systems using Willems' Fundamental Lemma. We show that if the adversary is able to upper bound the order of a linear, time-invariant system and read all its inputs and outputs, then the adversary will be able to generate undetectable attack signals in the form of covert attacks. Additionally, we provide conditions on the disclosed data set that enable the adversary to generate zero dynamics attacks. These conditions give operators insights into when enough information about the system has been revealed for an adversary to conduct an undetectable attack. Finally, the different attack strategies are verified through a numerical example.","Title: A Game-Theoretic Framework for Security-Aware Sensor Placement Problem in Networked Control Systems\nYear: 2022\n\nAbstract: This article studies the sensor placement problem in a leader–follower networked control system for improving its security against cyber-physical attacks. In a zero-sum game, the attacker selects \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$f$</tex-math></inline-formula>\n nodes of the network to attack, and the detector places \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$f$</tex-math></inline-formula>\n sensors to detect the presence of the attack signals. In our formulation, the attacker’s objective is to have a large impact on a target node in the network while being as little visible as possible to the detector. The detector, however, seeks to maximize the visibility of the attack signals. The effects of the attack signals on both the target node and the detector node are captured via the system \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$L_2$</tex-math></inline-formula>\n gain from the attack signals to the target node and deployed sensors’ outputs, respectively. The equilibrium strategy of the game determines the optimal locations of the sensors. The existence of Nash equilibrium for the single-attack single-sensor case is studied when the underlying connectivity graph is a directed or an undirected tree. We show that, under the optimal sensor placement strategy, an undirected topology provides a higher security level for a networked control system compared to its corresponding directed topology. For the multiple-attack multiple-sensor case, we show that the game does not necessarily admit a Nash equilibrium and introduce a Stackelberg game approach, where the detector acts as the leader. Finally, these results are used to study the sensor placement problem in a vehicle platooning application in the presence of bias injectionattacks."],"string":"[\n \"Title: Revealing stealthy attacks in control systems.\\nYear: 2012\\n\\nAbstract: In this paper the problem of revealing stealthy data-injection attacks on control systems is addressed. In particular we consider the scenario where the attacker performs zero-dynamics attacks on the system. First, we characterize and analyze the stealthiness properties of these attacks for linear time-invariant systems. Then we tackle the problem of detecting such attacks by modifying the system's structure. Our results provide necessary and sufficient conditions that the modifications should satisfy in order to detect the zero-dynamics attacks. The results and proposed detection methods are illustrated through numerical examples.\",\n \"Title: A Cyber Security Study of a SCADA Energy Management System: Stealthy Deception Attacks on the State Estimator\\nYear: 2010\\n\\nAbstract: The electrical power network is a critical infrastructure in today's society,\\nso its safe and reliable operation is of major concern. State estimators are\\ncommonly used in power networks, for example, to detect faulty equipment and to\\noptimally route power flows. The estimators are often located in control\\ncenters, to which large numbers of measurements are sent over unencrypted\\ncommunication channels. Therefore cyber security for state estimators becomes\\nan important issue. In this paper we analyze the cyber security of state\\nestimators in supervisory control and data acquisition (SCADA) for energy\\nmanagement systems (EMS) operating the power network. Current EMS state\\nestimation algorithms have bad data detection (BDD) schemes to detect outliers\\nin the measurement data. Such schemes are based on high measurement redundancy.\\nAlthough these methods may detect a set of basic cyber attacks, they may fail\\nin the presence of an intelligent attacker. We explore the latter by\\nconsidering scenarios where stealthy deception attacks are performed by sending\\nfalse information to the control center. We begin by presenting a recent\\nframework that characterizes the attack as an optimization problem with the\\nobjective specified through a security metric and constraints corresponding to\\nthe attack cost. The framework is used to conduct realistic experiments on a\\nstate-of-the-art SCADA EMS software for a power network example with 14\\nsubstations, 27 buses, and 40 branches. The results indicate how state\\nestimators for power networks can be made more resilient to cyber security\\nattacks.\",\n \"Title: Design of State-based Schedulers for a Network of Control Loops\\nYear: 2012\\n\\nAbstract: For a closed-loop system with a contention-based multiple access network on its sensor link, the medium access controller (MAC) may discard some packets when the traffic on the link is high. We use a local state-based scheduler to select a few critical data packets to send to the MAC. In this paper, we analyze the impact of such a scheduler on the closed-loop system in the presence of traffic, and show that there is a dual effect with state-based scheduling. In general, this makes the optimal scheduler and controller hard to find. However, by removing past controls from the scheduling criterion, we find that certainty equivalence holds. This condition is related to the classical result of Bar-Shalom and Tse, and it leads to the design of an innovations-based scheduler with a certainty equivalent controller. However, this controller is not an equivalent design for the optimal controller, in the sense of Witsenhausen. The computation of the estimate can be simplified by introducing a symmetry constraint on the scheduler. Based on these findings, we propose a dual predictor architecture for the closed-loop system, which ensures separation between scheduler, observer and controller. We present an example of this architecture, which illustrates a network-aware event-triggering mechanism.\",\n \"Title: Stability analysis of multiple state-based schedulers with CSMA.\\nYear: 2012\\n\\nAbstract: In this paper, we identify sufficient conditions for Lyapunov Mean Square Stability (LMSS) of a contention-based network of first-order systems, with state-based schedulers. The stability analysis helps us to choose policies for adapting the scheduler threshold to the delay from the network and scheduler. We show that three scheduling laws can result in LMSS: constant-probability laws and additively increasing or decreasing probability laws. Our results counter the notions that increasing probability scheduling laws alone can guarantee stability of the closed-loop system, or that decreasing probability scheduling laws are required to mitigate congestion in the network.\",\n \"Title: On Lossless Approximations, the Fluctuation-Dissipation Theorem, and Limitations of Measurements\\nYear: 2011\\n\\nAbstract: In this paper, we take a control-theoretic approach to answering some\\nstandard questions in statistical mechanics, and use the results to derive\\nlimitations of classical measurements. A central problem is the relation\\nbetween systems which appear macroscopically dissipative but are\\nmicroscopically lossless. We show that a linear system is dissipative if, and\\nonly if, it can be approximated by a linear lossless system over arbitrarily\\nlong time intervals. Hence lossless systems are in this sense dense in\\ndissipative systems. A linear active system can be approximated by a nonlinear\\nlossless system that is charged with initial energy. As a by-product, we obtain\\nmechanisms explaining the Onsager relations from time-reversible lossless\\napproximations, and the fluctuation-dissipation theorem from uncertainty in the\\ninitial state of the lossless system. The results are applied to measurement\\ndevices and are used to quantify limits on the so-called observer effect, also\\ncalled back action, which is the impact the measurement device has on the\\nobserved system. In particular, it is shown that deterministic back action can\\nbe compensated by using active elements, whereas stochastic back action is\\nunavoidable and depends on the temperature of the measurement device.\",\n \"Title: The Statistical Mechanics Of Fluctuation-Dissipation And Measurement Back Action\\nYear: 2007\\n\\nAbstract: In this paper, we take a control-theoretic approach to answering some standard questions in statistical mechanics. A central problem is the relation between systems which appear macroscopically dissipative but are microscopically lossless. We show that a linear macroscopic system is dissipative if and only if it can be approximated by a linear lossless microscopic system, over arbitrarily long time intervals. As a by-product, we obtain mechanisms explaining Johnson-Nyquist noise as initial uncertainty in the lossless state, as well as measurement back action and a trade-off between process and measurement noise.\",\n \"Title: Stability Analysis and Design of a Network of Event-based Systems.\\nYear: 2014\\n\\nAbstract: We consider a network of event-based systems that use a shared wireless medium to communicate with their respective controllers. These systems use a contention resolution mechanism to arbitrate access to the shared network. We identify sufficient conditions for Lyapunov mean square stability of each control system in the network, and design event-based policies that guarantee it. Our stability analysis is based on a Markov model that removes the network-induced correlation between the states of the control systems in the network. Analyzing the stability of this Markov model remains a challenge, as the event-triggering policy renders the estimation error non-Gaussian. Hence, we identify an auxiliary system that furnishes an upper bound for the variance of the system states. Using the stability analysis, we design policies, such as the constant-probability policy, for adapting the event-triggering thresholds to the delay in accessing the network. Realistic wireless networked control examples illustrate the applicability of the presented approach.\",\n \"Title: Computing the L2 gain for linear periodic continuous-time systems\\nYear: 2009\\n\\nAbstract: A method to compute the L2 gain is developed for the class of linear periodic continuous-time systems that admit a finite-dimensional state-space realisation. A bisection search for the smallest upper bound on the gain is employed, where at each step an equivalent discrete-time problem is considered via the well-known technique of time-domain lifting. The equivalent problem involves testing a bound on the gain of a linear shift-invariant discrete-time system, with the same state dimension as the periodic continuous-time system. It is shown that a state-space realisation of the discrete-time system can be constructed from point solutions to a linear differential equation and two differential Riccati equations, all subject to only single-point boundary conditions. These are well behaved over the corresponding one period intervals of integration, and as such, the required point solutions can be computed via standard methods for ordinary differential equations. A numerical example is presented and comparisons made with alternative techniques.\",\n \"Title: Scheduling smart home appliances using mixed integer linear programming\\nYear: 2011\\n\\nAbstract: This paper considers the minimum electricity cost scheduling problem of smart home appliances. Operation characteristics, such as expected duration and peak power consumption of the smart appliances, can be adjusted through a power profile signal. The optimal power profile signal minimizes cost, while satisfying technical operation constraints and consumer preferences. Constraints such as enforcing uninterruptible and sequential operations are modeled in the proposed framework using mixed integer linear programming (MILP). Several realistic scenarios based on actual spot price are considered, and the numerical results provide insight into tariff design. Computational issues and extensions of the proposed scheduling framework are also discussed.\",\n \"Title: A bode sensitivity integral for linear time-periodic systems\\nYear: 2005\\n\\nAbstract: Bode's sensitivity integral is a well-known formula that quan- tifies some of the limitations in feedback control for linear time-invariant systems. In this note, we show that there is a similar formula for linear time-periodic systems. The harmonic transfer function is used to prove the result. We use the notion of roll-off 2, which means that the first time- varying Markov parameter is equal to zero. It then follows that the har- monic transfer function is an analytic operator and a trace class operator. These facts are used to prove the result.\",\n \"Title: Model reduction of networked passive systems through clustering\\nYear: 2013\\n\\nAbstract: In this paper, a model reduction procedure for a network of interconnected identical passive subsystems is presented. Here, rather than performing model reduction on the subsystems, adjacent subsystems are clustered, leading to a reduced-order networked system that allows for a convenient physical interpretation. The identification of the subsystems to be clustered is performed through controllability and observability analysis of an associated edge system and it is shown that the property of synchronization (i.e., the convergence of trajectories of the subsystems to each other) is preserved during reduction. The results are illustrated by means of an example.\",\n \"Title: Distributed fault detection for interconnected second-order systems.\\nYear: 2011\\n\\nAbstract: In this paper, the existence of unknown input observers for networks of interconnected second-order linear time invariant systems is studied. Two classes of distributed control systems of large practical relevance are considered. It is proved that for these systems, one can construct a bank of unknown input observers, and use them to detect and isolate faults in the network. The result presents a distributed implementation. In particular, by exploiting the system structure, this work provides further insight into the design of UIO for networked systems. Moreover, the importance of certain network measurements is shown. Infeasibility results with respect to available measurements and faults are also provided, as well as methods to remove faulty agents from the network. Applications to power networks and robotic formations are presented. It is shown how the developed methodology apply to a power network described by the swing equation with a faulty bus. For a multi-robot system, it is illustrated how a faulty robot can be detected and removed.\",\n \"Title: Performance Analysis of a Network of Event-based Systems.\\nYear: 2014\\n\\nAbstract: We consider a scenario where multiple event-based systems use a contention resolution mechanism (CRM) to communicate with their respective controllers over a wireless network. We present a Markov model that captures the joint interactions of the event-triggering policy and the CRM. This model is obtained by decoupling interactions between the different systems in the network, drawing inspiration from Bianchi's analysis of IEEE 802.11. We present Monte-Carlo simulations that validate our model under various network configurations, and verify the accuracy of the performance analysis.\",\n \"Title: Challenges in Power System Information Security\\nYear: 2012\\n\\nAbstract: Achieving all-encompassing component-level security in power system IT infrastructures is difficult, owing to its cost and potential performance implications.\",\n \"Title: Agents misbehaving in a network: a vice or a virtue?\\nYear: 2012\\n\\nAbstract: Misbehaviors among the agents in a network might be intentional or unintentional, they might cause a system-wide failure or they might improve the performance or even enable us to achieve an objective. In this article we consider examples of these possible scenarios. First, we argue the necessity of monitoring the agents in a network to detect if they are misbehaving or not and outline a distribut...\",\n \"Title: Electric power network security analysis via minimum cut relaxation\\nYear: 2011\\n\\nAbstract: In this paper an efficient computation scheme for analyzing the security of power transmission networks is presented. In order to strategically allocate protection devices in the network, the problem of finding the sparsest stealthy false data attack to the state estimator is studied. While the attack search problem is traditionally solved as a generic constrained cardinality minimization problem, this paper exploits the problem structure intrinsic to the power network application to obtain a polynomial time approximate algorithm based on a minimum cut relaxation. Experiment results from realistic test cases are presented to demonstrate the efficiency and accuracy of the proposed algorithm.\",\n \"Title: Cyber-security of SCADA systems\\nYear: 2012\\n\\nAbstract: After a general introduction of the VIKING EU FP7 project two specific cyber-attack mechanisms, which have been analyzed in the VIKING project, will be discussed in more detail. Firstly an attack and its consequences on the Automatic Generation Control (AGC) in a power system are investigated, and secondly the cyber security of State Estimators in SCADA systems is scrutinized.\",\n \"Title: Controllability of a class of networked passive linear systems\\nYear: 2013\\n\\nAbstract: In this paper, controllability properties of networks of diffusively coupled linear systems are considered through the controllability Gramian. For a class of passive linear systems, it is shown that the controllability Gramian can be decomposed into two parts. The first part is related to the dynamics of the individual systems whereas the second part is dependent only on the interconnection topology, allowing for a clear interpretation and efficient computation of controllability properties for a class of networked systems. Moreover, a relation between symmetries in the interconnection topology and controllability is given. The results are illustrated by an example.\",\n \"Title: Linear-Quadratic-Gaussian Heat Engines\\nYear: 2007\\n\\nAbstract: In this paper, we study the problem of extracting work from heat flows. In thermodynamics, a device doing this is called a heat engine. A fundamental problem is to derive hard limits on the efficiency of heat engines. Here we construct a linear-quadratic-Gaussian optimal controller that estimates the states of a heated lossless system. The measurements cool the system, and the surplus energy can be extracted as work by the controller. Hence, the controller acts like a Maxwell's demon. We compute the efficiency of the controller over finite and infinite time intervals, and since the controller is optimal, this yields hard limits. Over infinite time horizons, the controller has the same efficiency as a Carnot heat engine, and thereby it respects the second law of thermodynamics. As illustration we use an electric circuit where an ideal current source extracts energy from resistors with Johnson-Nyquist noise.\",\n \"Title: A case study in model reduction of linear time-varying systems\\nYear: 2006\\n\\nAbstract: In this paper, the balanced truncation procedure is applied to time-varying linear systems, both in continuous and in discrete time. The methods are applied to a linear approximation of a diesel exhaust catalyst model. The reduced-order systems are obtained by using certain projections instead of direct balancing. An approximate zero-order-hold discretization of continuous-time systems is described, and a new a priori approximation error bound for balanced truncation in the discrete-time case is obtained. The case study shows that there are several advantages to work in discrete time. It gives simpler implementation with fewer computations.\",\n \"Title: Network-Aware Mitigation of Data Integrity Attacks on Power System State Estimation.\\nYear: 2012\\n\\nAbstract: Critical power system applications like contingency analysis and optimal power flow calculation rely on the power system state estimator. Hence the security of the state estimator is essential for the proper operation of the power system. In the future more applications are expected to rely on it, so that its importance will increase. Based on realistic models of the communication infrastructure used to deliver measurement data from the substations to the state estimator, in this paper we investigate the vulnerability of the power system state estimator to attacks performed against the communication infrastructure. We define security metrics that quantify the importance of individual substations and the cost of attacking individual measurements. We propose approximations of these metrics, that are based on the communication network topology only, and we compare them to the exact metrics. We provide efficient algorithms to calculate the security metrics. We use the metrics to show how various network layer and application layer mitigation strategies, like single and multi-path routing and data authentication, can be used to decrease the vulnerability of the state estimator. We illustrate the efficiency of the algorithms on the IEEE 118 and 300 bus benchmark power systems.\",\n \"Title: Active actuator fault detection and diagnostics in HVAC systems.\\nYear: 2012\\n\\nAbstract: This paper introduces a new method for performing actuator fault detection and diagnostics (FDD) in heating ventilation and air conditioning (HVAC) systems. The proposed actuator FDD strategy, for testing whether an actuator is stuck in a single position, uses a two-tier approach that includes a dynamic model-based detector and a fast-deciding steady-state detector. The model-based detector is formulated to provide detection performance that asymptotically bounds both the probability of miss and probability of false alarm. To provide a quick confirmation the actuator is working, the steady-state detector utilizes a goodness-of-fit detection strategy to decide if the measurements could be described by an actuator failure. An architecture is introduced that requires multiple steady-state detection experiments to decide that the measurements could be explained by an actuator failure before performing model-based detection. An experimental test bed using a the KTH Royal Institute of Technology campus HVAC system is described and used to evaluate the steady-state and model-based detectors. The experimental test bed is utilized to identify a building dynamics model, that is employed through monte carlo analysis, to characterize the detection performance of both the model-based detector and the steady-state detector.\",\n \"Title: Fault Detection and Mitigation in Kirchhoff Networks.\\nYear: 2012\\n\\nAbstract: In this letter, we study the problem of fault detection and mitigation in networks where the measurements satisfy Kirchhoff's voltage law. First, we characterise the class of faults appearing as an additive fault vector (injected by a malicious adversary or due to equipment failures) that can be detected by taking into account the topology of the network. Second, we consider the problem of estimat...\",\n \"Title: Computing Critical $k$-tuples in Power Networks\\nYear: 2012\\n\\nAbstract: In this paper the problem of finding the sparsest (i.e., minimum cardinality) critical k-tuple including one arbitrarily specified measurement is considered. The solution to this problem can be used to identify weak points in the measurement set, or aid the placement of new meters. The critical k-tuple problem is a combinatorial generalization of the critical measurement calculation problem. Using...\",\n \"Title: On performance limitations of congestion control\\nYear: 2009\\n\\nAbstract: Fundamental performance limitations on congestion control is discussed in relation to the information that is available in the controller. Three control architectures that all use bottle-neck buffer delay information of various form as inputs and sending rate as outputs are considered. It is shown that feedback delays from buffer to senders set limits on the achievable performance measured through fairness, efficiency and stability. We apply our findings to TCP FAST and can make some new interesting control theoretic interpretations of that protocol.\",\n \"Title: On Floquet-Fourier Realizations Of Linear Time-Periodic Impulse Responses\\nYear: 2006\\n\\nAbstract: We show that a linear time-periodic system with a smooth impulse response can be arbitrarily well approximated by a linear time-periodic state-space representation in so-called Floquet-Fourier form. The Floquet-Fourier form has a constant state matrix and the input and output matrices have only finitely many nonzero Fourier coefficients. Such representations are easier to use for analysis and control design than the impulse response or fully general state-space forms. The construction of the Floquet-Fourier form is done using methods for model approximation of infinite-dimensional linear time-invariant systems. We also propose a method for constructing minimal realizations from impulse responses of a special structure.\",\n \"Title: Complexity reduction for parameter-dependent linear systems\\nYear: 2012\\n\\nAbstract: We present a complexity reduction algorithm for a family of parameter-dependent linear systems when the system parameters belong to a compact semi-algebraic set. This algorithm potentially describes the underlying dynamical system with fewer parameters or state variables. To do so, it minimizes the distance (i.e., H∞-norm of the difference) between the original system and its reduced version. We present a sub-optimal solution to this problem using sum-of-squares optimization methods. We present the results for both continuous-time and discrete-time systems. Lastly, we illustrate the applicability of our proposed algorithm on numerical examples.\",\n \"Title: On the Exact Solution to a Smart Grid Cyber-Security Analysis Problem\\nYear: 2013\\n\\nAbstract: This paper considers a smart grid cyber-security problem analyzing the vulnerabilities of electric power networks to false data attacks. The analysis problem is related to a constrained cardinality minimization problem. The main result shows that an relaxation technique provides an exact optimal solution to this cardinality minimization problem. The proposed result is based on a polyhedral combinatorics argument. It is different from well-known results based on mutual coherence and restricted isometry property. The results are illustrated on benchmarks including the IEEE 118-bus, IEEE 300-bus, and the Polish 2383-bus and 2736-bus systems.\",\n \"Title: The Meaning of Structure in Interconnected Dynamic Systems\\nYear: 2011\\n\\nAbstract: Interconnected dynamic systems are a pervasive component of our modern infrastructures. The complexity of such systems can be staggering, which motivates simplified representations for their manipulation and analysis. This work introduces the complete computational structure of a system as a common baseline for comparing different simplified representations. Linear systems are then used as a vehicle for comparing and contrasting distinct partial structure representations. Such representations simplify the description of a system's complete computational structure at various levels of fidelity while retaining a full description of the system's input-output dynamic behavior. Relationships between these various partial structure representations are detailed, and the landscape of new realization, minimality, and model reduction problems introduced by these representations is briefly surveyed.\",\n \"Title: The conservation of information, towards an axiomatized modular modeling approach to congestion control\\nYear: 2013\\n\\nAbstract: We derive a modular fluid-flow network congestion control model based on a law of fundamental nature in networks: the conservation of information. Network elements such as queues, users, and transmission channels and network performance indicators like sending/acknowledgment rates and delays are mathematically modeled by applying this law locally. Our contributions are twofold. First, we introduce a modular metamodel that is sufficiently generic to represent any network topology. The proposed model is composed of building blocks that implement mechanisms ignored by the existing ones, which can be recovered from exact reduction or approximation of this new model. Second, we provide a novel classification of previously proposed models in the literature and show that they are often not capable of capturing the transient behavior of the network precisely. Numerical results obtained from packet-level simulations demonstrate the accuracy of the proposed model.\",\n \"Title: Data Attack Isolation in Power Networks Using Secure Voltage Magnitude Measurements\\nYear: 2014\\n\\nAbstract: In this paper a procedure to detect and isolate data attacks on power network power flow measurements is proposed. This method can be used in conjunction with available bad data detection (BDD) methods to isolate multiple bad data which are otherwise difficult to handle. The proposed procedure relies on secure measurements of bus voltage magnitudes to define a measurement residual using potentially compromised active and reactive power flow measurements on transmission lines. The proposed residual can be calculated in real-time. In addition, the component of the proposed residual on any particular line depends only locally on the component of the data attack on the same line. This makes the proposed residual well-suited for distributed data attack isolation in large-scale power networks. Furthermore, it can be shown that the proposed procedure becomes more effective when measurements from multiple time instances can be utilized. A detailed numerical case study on the IEEE 14-bus benchmark system demonstrates the effectiveness of the proposed procedure.\",\n \"Title: Attack models and scenarios for networked control systems\\nYear: 2012\\n\\nAbstract: Cyber-secure networked control is modeled, analyzed, and experimentally illustrated in this paper. An attack space defined by the adversary's system knowledge, disclosure, and disruption resources is introduced. Adversaries constrained by these resources are modeled for a networked control system architecture. It is shown that attack scenarios corresponding to replay, zero dynamics, and bias injection attacks can be analyzed using this framework. An experimental setup based on a quadruple-tank process controlled over a wireless network is used to illustrate the attack scenarios, their consequences, and potential counter-measures.\",\n \"Title: Frequency-Weighted Model Reduction With Applications To Structured Models\\nYear: 2007\\n\\nAbstract: In this paper, a frequency-weighted extension of a recently proposed model reduction method for linear systems is presented. The method uses convex optimization and can be used both with sample data and exact models. We also obtain bounds on the frequency-weighted error. The method is combined with a rank-minimization heuristic to approximate multi-input-multi-output systems. We also present two applications environment compensation and simplification of interconnected models - where we argue the proposed methods are useful.\",\n \"Title: Structured Model Order Reduction of Parallel Models in Feedback.\\nYear: 2013\\n\\nAbstract: Parallel working units in closed-loop operation are frequently encountered in industrial applications of advanced process control (boilers, turbines, chemical reactors, etc.). Control strategies typically require different low-order models for each configuration of parallel units. These different models are usually obtained by heuristics applied to the parallel models. To replace these heuristics, this paper proposes a systematic solution based on structured model order reduction. Two methods are considered, the first has general applicability to stable closed-loop systems, but gives no a priori error bounds; the second linear matrix inequality (LMI)-based method comes with an explicit error bounds, but cannot be applied to general models. However, it is shown that for models composed of cascades of stable subsystems and negative feedbacks of strictly positive real subsystems, the LMIs are always feasible. Both methods are demonstrated on a practical example of a cogeneration power plant with multiple boilers. It is proved that the second LMI-based method can always be applied to general problems with structures similar to the boiler-header systems considered in this paper.\",\n \"Title: An Axiomatic Fluid-Flow Model For Congestion Control Analysis\\nYear: 2011\\n\\nAbstract: An axiomatic model for congestion control is derived. The proposed four axioms serve as a basis for the construction of models for the network elements. It is shown that, under some assumptions, some models of the literature can be recovered. A single-buffer/multiple-users topology is finally derived and studied for illustration.\",\n \"Title: Efficient Computations of a Security Index for False Data Attacks in Power Networks.\\nYear: 2014\\n\\nAbstract: The resilience of Supervisory Control and Data Acquisition (SCADA) systems for electric power networks for certain cyber-attacks is considered. We analyze the vulnerability of the measurement system to false data attack on communicated measurements. The vulnerability analysis problem is shown to be NP-hard, meaning that unless P=NP there is no polynomial time algorithm to analyze the vulnerability of the system. Nevertheless, we identify situations, such as the full measurement case, where the analysis problem can be solved efficiently. In such cases, we show indeed that the problem can be cast as a generalization of the minimum cut problem involving nodes with possibly nonzero costs. We further show that it can be reformulated as a standard minimum cut problem (without node costs) on a modified graph of proportional size. An important consequence of this result is that our approach provides the first exact efficient algorithm for the vulnerability analysis problem under the full measurement assumption. Furthermore, our approach also provides an efficient heuristic algorithm for the general NP-hard problem. Our results are illustrated by numerical studies on benchmark systems including the IEEE 118-bus system.\",\n \"Title: Dissipativity-Preserving Model Reduction for Large-Scale Distributed Control Systems\\nYear: 2015\\n\\nAbstract: We propose a dissipativity-preserving structured model reduction method for distributed control systems. As a fundamental tool to develop structured model reduction, we first establish dissipativity-preserving model reduction for general linear systems on the basis of a singular perturbation approximation. To this end, by deriving a tractable expression of singular perturbation models, we characterize dissipativity preservation in terms of a projection-like transformation of storage functions, and we show that the resultant approximation error is relevant to the sum of neglected eigenvalues of an index matrix. Next, utilizing this dissipativity-preserving model reduction, we develop a structured controller reduction method for distributed control systems. The major significance of this method is to preserve the spatial distribution of dissipative controllers and to provide an a priori bound for the performance degradation of closed-loop systems in terms of the H2-norm. The efficiency of the proposed method is verified through a numerical example of vibration suppression control for interconnected second-order systems.\",\n \"Title: Simplify: A Toolbox For Structured Model Reduction\\nYear: 2014\\n\\nAbstract: In this paper, we present a toolbox for structured model reduction developed for MATLAB. In addition to structured model reduction methods using balanced realizations of the subsystems, we introduce a numerical algorithm for structured model reduction using a subgradient optimization algorithm. We briefly present the syntax for the toolbox and its features. Finally, we demonstrate the applicability of various model reduction methods in the toolbox on a structured mass-spring mechanical system.\",\n \"Title: Multiple-Loop Self-Triggered Model Predictive Control for Network Scheduling and Control\\nYear: 2015\\n\\nAbstract: We present an algorithm for controlling and scheduling multiple linear time-invariant processes on a shared bandwidth-limited communication network using adaptive sampling intervals. The controller is centralized and not only computes at every sampling instant the new control command for a process but also decides the time interval to wait until taking the next sample.The approach relies on model predictive control ideas, where the cost function penalizes the state and control effort as well as the time interval until the next sample is taken. The latter is introduced to generate an adaptive sampling scheme for the overall system such that the sampling time increases as the norm of the system state goes to zero. This paper presents a method for synthesizing such a predictive controller and gives explicit sufficient conditions for when it is stabilizing. Further explicit conditions are given that guarantee conflict free transmissions on the network. It is shown that the optimization problem may be solved offline and that the controller can be implemented as a lookup table of state feedback gains. The simulation studies which compare the proposed algorithm to periodic sampling illustrate potential performance gains.\",\n \"Title: Approximative model reconstruction of cascade systems.\\nYear: 2014\\n\\nAbstract: This letter considers how to approximately reconstruct a cascade system from a given unstructured system estimate. Many system identification methods, including subspace methods, provide reliable but generally unstructured black-box models. The problem we consider is how to find cascade systems that are close to such black-box models. For this, we use model matching techniques and optimal weighted Hankel-norm approximation to obtain accurate low-order cascade systems. We show that it is possible to bound the reconstruction error in terms of an error tolerance parameter and weighted Hankel singular values. The suggested methods are illustrated on both a numerical example and a real double tank system with experimental data.\",\n \"Title: A secure control framework for resource-limited adversaries.\\nYear: 2015\\n\\nAbstract: Cyber-secure networked control is modeled, analyzed, and experimentally illustrated in this paper. An attack space defined by the adversary’s model knowledge, disclosure, and disruption resources is introduced. Adversaries constrained by these resources are modeled for a networked control system architecture. It is shown that attack scenarios corresponding to denial-of-service, replay, zero-dynamics, and bias injection attacks on linear time-invariant systems can be analyzed using this framework. Furthermore, the attack policy for each scenario is described and the attack’s impact is characterized using the concept of safe sets. An experimental setup based on a quadruple-tank process controlled over a wireless network is used to illustrate the attack scenarios, their consequences, and potential counter-measures.\",\n \"Title: Distributed PI-control with applications to power systems frequency control\\nYear: 2014\\n\\nAbstract: This paper considers a distributed PI-controller for networked dynamical systems. Sufficient conditions for when the controller is able to stabilize a general linear system and eliminate static control errors are presented. The proposed controller is applied to frequency control of power transmission systems. Sufficient stability criteria are derived, and it is shown that the controller parameters can always be chosen so that the frequencies in the closed loop converge to nominal operational frequency. We show that the load sharing property of the generators is maintained, i.e., the input power of the generators is proportional to a controller parameter. The controller is evaluated by simulation on the IEEE 30 bus test network, where its effectiveness is demonstrated.\",\n \"Title: Energy and CO2 efficient scheduling of smart appliances in active houses equipped with batteries\\nYear: 2014\\n\\nAbstract: In this paper, we present a novel method for scheduling smart appliances and batteries, in order to reduce both the electricity bill and the CO2 emissions. Mathematically, the scheduling problem is posed as a multi-objective Mixed Integer Linear Programming (MILP), which can be solved by using standard algorithms. A case study is performed to assess the performance of the proposed scheduling framework. Numerical results show that the new formulation can decrease both the CO2 emissions and the electricity bill. Furthermore, a survey of studies that deal with scheduling of smart appliances is provided. These papers use methods based on MILP, Dynamic Programming (DP), and Minimum Cut Algorithm (MCA) for solving the scheduling problem. We discuss their performance in terms of computation time and optimality versus time discretization and number of appliances.\",\n \"Title: Wiretap codes for secure multi-party computation\\nYear: 2014\\n\\nAbstract: In this paper, we propose a new secret sharing scheme for secure multi-party computation. We present a general framework that allows us to construct efficient secret sharing schemes from channel coding techniques for the wiretap channel. The resulting schemes can be employed to securely calculate linear functions of data that are distributed in a network without leaking any information on the data except the desired result. For the examples considered in this paper, our schemes minimize the communication overhead while keeping the data perfectly secure. Compared to conventional schemes, for which the communication overhead grows quadratically in the number of clients in the considered scenarios, the communication overhead for our approach grows only linearly with the number of clients. This property is maintained even if our secret sharing scheme is set up to introduce redundancy in order to compensate for losses of secret shares. While we only consider the case of passive eavesdroppers and implementations based on nested Reed-Solomon codes in this paper, the proposed framework can also be applied in other cases (e.g., when clients tamper with the data) by taking into account the effects of attacks in the design of the underlying wiretap code.\",\n \"Title: Distributed Control of Networked Dynamical Systems: Static Feedback, Integral Action and Consensus\\nYear: 2014\\n\\nAbstract: This paper analyzes distributed control protocols for first- and second-order networked dynamical systems. We propose a class of nonlinear consensus controllers where the input of each agent can be written as a product of a nonlinear gain, and a sum of nonlinear interaction functions. By using integral Lyapunov functions, we prove the stability of the proposed control protocols, and explicitly characterize the equilibrium set. We also propose a distributed proportional-integral (PI) controller for networked dynamical systems. The PI controllers successfully attenuate constant disturbances in the network. We prove that agents with single-integrator dynamics are stable for any integral gain, and give an explicit tight upper bound on the integral gain for when the system is stable for agents with double-integrator dynamics. Throughout the paper we highlight some possible applications of the proposed controllers by realistic simulations of autonomous satellites, power systems and building temperature control.\",\n \"Title: Distributed Fault Detection and Isolation Resilient to Network Model Uncertainties\\nYear: 2014\\n\\nAbstract: The ability to maintain state awareness in the face of unexpected and unmodeled errors and threats is a defining feature of a resilient control system. Therefore, in this paper, we study the problem of distributed fault detection and isolation (FDI) in large networked systems with uncertain system models. The linear networked system is composed of interconnected subsystems and may be represented as a graph. The subsystems are represented by nodes, while the edges correspond to the interconnections between subsystems. Considering faults that may occur on the interconnections and subsystems, as our first contribution, we propose a distributed scheme to jointly detect and isolate faults occurring in nodes and edges of the system. As our second contribution, we analyze the behavior of the proposed scheme under model uncertainties caused by the addition or removal of edges. Additionally, we propose a novel distributed FDI scheme based on local models and measurements that is resilient to changes outside of the local subsystem and achieves FDI. Our third contribution addresses the complexity reduction of the distributed FDI method, by characterizing the minimum amount of model information and measurements needed to achieve FDI and by reducing the number of monitoring nodes. The proposed methods can be fused to design a scalable and resilient distributed FDI architecture that achieves local FDI despite unknown changes outside the local subsystem. The proposed approach is illustrated by numerical experiments on the IEEE 118-bus power network benchmark.\",\n \"Title: Control of MTDC transmission systems under local information\\nYear: 2014\\n\\nAbstract: High-voltage direct current (HVDC) is a commonly used technology for long-distance electric power transmission, mainly due to its low resistive losses. In this paper a distributed controller for multi-terminal high-voltage direct current (MTDC) transmission systems is considered. Sufficient conditions for when the proposed controller renders the closed-loop system asymptotically stable are provided. Provided that the closed loop system is asymptotically stable, it is shown that in steady-state a weighted average of the deviations from the nominal voltages is zero. Furthermore, a quadratic cost of the current injections is minimized asymptotically.\",\n \"Title: Model reduction of linear systems using extended balanced truncation\\nYear: 2008\\n\\nAbstract: An extension to balanced truncation is presented. Balanced truncation is a standard method for model reduction and it has many good properties, such as preservation of model stability and a priori error bounds. Balanced truncation is done using controllability and observability Gramians. The Gramians can be found by solving a set of linear matrix inequalities. In this paper, we show that these linear matrix inequalities can be extended so that the number of decision variables are at least doubled. This leads to the concept of extended Gramians. It is shown that all the good properties of balanced truncation also hold for extended balanced truncation. It turns out that extended balanced truncation is especially useful when there are additional structure constraints in the model to be reduced. This is useful in frequency-weighted reduction, for example. Model reduction is about systematic simplification of com- plex models. This is a topic that has received a great deal of interest at least since the early 1980's, but still hard problems remain to be solved. In particular, most available methods that are guaranteed to deliver good approximations only apply to linear systems, and these methods are usually not structure preserving. In this paper, we propose an extension to balanced truncation that increases the chance of preserving structures.\",\n \"Title: Estimation over heterogeneous sensor networks\\nYear: 2008\\n\\nAbstract: Design trade-offs between estimation perfor- mance, processing delay and communication cost for a sensor scheduling problem is discussed. We consider a heterogeneous sensor network with two types of sensors: the first type has low-quality measurements, small processing delay and a light communication cost, while the second type is of high quality, but imposes a large processing delay and a high communication cost. Such a heterogeneous sensor network is common in applications, where for instance in a localization system the poor sensor can be an ultrasound sensor while the more powerful sensor can be a camera. Using a time-periodic Kalman filter, we show how one can find an optimal schedule of the sensor communication. One can significantly improve estimation quality by only using the expensive sensor rarely. We also demonstrate how simple sensor switching rules based on the Riccati equation drives the filter into a stable time-periodic Kalman filter. I. INTRODUCTION\",\n \"Title: Cascade structural model approximation of identified state space models\\nYear: 2008\\n\\nAbstract: General black-box system identification tech- niques such as subspace system identification and FIR/ARX least squares system identification are commonly used to identify multi-input multi-output models from experimental data. However, in many applications there are a priori given structural information. Here the focus is on linear dynamical systems with a cascade structure, and with one input signal and two output signals. Models of such systems are important in e.g. cascade control applications. It is possible to incorporate such a structure in a prediction error method, which, however, is based on rather advanced numerical non-convex optimization techniques to calculate the corresponding structured model estimate. We will instead study how to use model approximation techniques to approximate a general black-box estimate with a structured model. This will avoid the use of numerical optimization and works well with e.g. subspace system identifi- cation, which is a standard method in process industry where cascade systems are very common. The problems of cascade structural model approximation and model reduction are rather non-standard, and we will study several new methods. The basic idea is to first find a higher order but structured model approximation using standard H∞ model matching techniques, and then in a second step use so-called structured balanced model reduction to find lower order structured approximation. Structured balanced model reduction is a rather new approach, with powerful model order selection tools and error bound results. The results of the corresponding two step model approximation approach seem promising, as illustrated by a simple numerical example. I. INTRODUCTION\",\n \"Title: Steady state performance analysis of multiple state-based schedulers with CSMA\\nYear: 2011\\n\\nAbstract: In this paper, we analyze the performance of multiple event-based systems that share access to the same network. Transmissions are attempted only when a local state-based scheduler generates an event, and access to the network is determined using a Carrier Sensing Multiple Access (CSMA) protocol. In general, the interactions in such a multiple access network introduce correlations between the system variables of the various loops, and the respective traffic contributions as well. Hence, analyzing the performance of this network is difficult. However, a class of state-based schedulers, introduced in the paper, permits a joint analysis of the scheduler and the Contention Resolution Mechanism (CRM). The analysis is based on a Markov model, which is validated through simulations. The resulting steady-state model makes it possible to characterize the statistics of packet arrivals in this network.\",\n \"Title: Dynamical system decomposition using dissipation inequalities\\nYear: 2011\\n\\nAbstract: In this paper we investigate stability and interaction measures for interconnected systems that have been produced by decomposing a large-scale linear system into a set of lower order subsystems connected in feedback. We begin by analyzing the requirements for asymptotic stability through generalized dissipation inequalities and storage functions. Using this insight we then describe various metrics based on a system's energy dissipation to determine how strongly the subsystems interact with each other. From these metrics a decomposition algorithm is described.\",\n \"Title: Distributed Fault Detection and Isolation with imprecise network models\\nYear: 2012\\n\\nAbstract: In this paper we consider the problem of Distributed Fault Detection and Isolation (D-FDI) in large networked systems with imprecise models. Taking a previously proposed D-FDI scheme for a given initial network model, we analyze its performance under small changes in the network graph, namely the addition or removal of edges. Under some assumptions, it is shown that for this kind of perturbations there exist suitable thresholds for which fault detection and isolation is achieved. As our second contribution, we propose solutions to accomplish D-FDI with considerably lower computational burden, while handling imprecise network models. Numerical experiments demonstrating the effectiveness of the proposed solution are presented, taking the IEEE 118 bus power network as an example.\",\n \"Title: Distributed integral action: Stability analysis and frequency control of power systems\\nYear: 2012\\n\\nAbstract: This paper analyzes distributed proportional-integral controllers. We prove that integral action can be successfully applied to consensus algorithms, where attenuation of static disturbances is achieved. These control algorithms are applied to decentralized frequency control of electrical power systems. We show that the proposed algorithm can attenuate step disturbances of power loads. We provide simulations of the proposed control algorithm on the IEEE 30 bus test system that demonstrate its efficiency.\",\n \"Title: On subspace identification of cascade structured systems\\nYear: 2010\\n\\nAbstract: In identification it is important to take a priori structural information into account in many applications, something that is difficult when using subspace methods. Here will study how to incorporate a special structure, a cascade structure with two subsystems. Two new methods are derived for estimating system with this structure. The problem when using subspace identification on cascade structured system is that the states from the first subsystem are mixed with states from the second subsystem via a unknown similarity transform. The first indirect method finds a similarity transform that takes the system back to a form such that the subsystems can be recovered. The second method uses the fact that the structure of the extended observability matrix is known for cascade systems. However, it only works when both subsystems have order one. In practice this is still a common case. The results of the two methods seem promising, as illustrated by applying the methods to a real process, the double tank process. The performance is comparable with state of the art methods. Finally the problem of optimal input design for cascade systems are introduced, and illustrated by a simple example.\",\n \"Title: Towards a thermodynamics of control: Entropy, energy and Kalman filtering\\nYear: 2013\\n\\nAbstract: We propose a method to analyse the flows of information and energy between two systems (plant and controller) connected in feedback. Extending a work by Touchette and Lloyd (2000, 2004), we estimate the advantage, both in terms of entropy reduction and energy extraction, of a feedback controller over an open-loop control in terms of the information on the plant state that is available to the controller. By energy here we mean any objective function that we seek to minimize, for example the square of the state. We apply this methodology on the Kalman filter, and develop a physical interpretation comparable to Mitter and Newton's (2005).\",\n \"Title: Reduced-order predictive outage compensators for networked systems\\nYear: 2009\\n\\nAbstract: Control systems utilizing wireless sensor and ac- tuator networks can be severely affected by the properties of the wireless links. Radio fading and interference may cause communication outage of several samples in situations when the radio environment is noisy and low transmission power is desirable. We propose a method to compensate for outages by introducing a predictive outage compensator (POC), which is a filter to be implemented at the receiver sides of networked control systems and that generates artificial samples during the outage. The main contribution of the paper is to show that a POC can be derived based on a Kalman filter formulation and that it is possible to achieve good performance with a low- order implementation based on Hankel norm approximation. Tradeoffs between achievable closed-loop performance, outage length, and POC order are discussed. The results are illustrated on a simulated example of a multiple-tank process.\",\n \"Title: Network structure preserving model reduction with weak a priori structural information\\nYear: 2009\\n\\nAbstract: This paper extends a state projection method for structure preserving model reduction to situations where only a weaker notion of system structure is available. This weaker notion of structure, identifying the causal relationship between manifest variables of the system, is especially relevant is settings such as systems biology, where a clear partition of state variables into distinct subsystems may be unknown, or not even exist. The resulting technique, like similar approaches, does not provide theoretical performance guarantees, so an extensive computational study is conducted, and it is observed to work fairly well in practice. Moreover, conditions characterizing structurally minimal realizations and sufficient conditions characterizing edge loss resulting from the reduction process, are presented.\",\n \"Title: Parameterized model order reduction using extended balanced truncation\\nYear: 2012\\n\\nAbstract: We show how extended balanced truncation can be applied to the parameterized model order reduction (PMOR) problem. Two variants are introduced and are shown to improve already available a priori error bounds, as well as actual approximation errors in a numerical experiment.\",\n \"Title: Voltage control for interconnected microgrids under adversarial actions\\nYear: 2015\\n\\nAbstract: In this paper, we study the impact of adversarial actions on voltage control schemes in interconnected microgrids. Each microgrid is abstracted as a power inverter that can be controlled to regulate its voltage magnitude and phase-angle independently. Moreover, each power inverter is modeled as a single integrator, whose input is given by a voltage droop-control policy that is computed based on voltage magnitude and reactive power injection measurements. Under mild assumptions, we then establish important properties of the nominal linearized closed-loop system, such as stability, positivity, and diagonal dominance. These properties play an important role when characterizing the potential impact of different attack scenarios. In particular, we discuss two attack scenarios where the adversary corrupts measurement data and reference signals received by the voltage droop controllers. The potential impact of instances of each scenario is analyzed using control-theoretic tools, which may be used to develop methodologies for identifying high-risk attack scenarios, as is illustrated by numerical examples.\",\n \"Title: Robust Scheduling of Smart Appliances in Active Apartments With User Behavior Uncertainty\\nYear: 2016\\n\\nAbstract: In this paper, we propose a robust approach for scheduling of smart appliances and electrical energy storages (EESs) in active apartments with the aim of reducing both the electricity bill and the $hbox{CO}_{2}$ emissions. The proposed robust formulation takes the user behavior uncertainty into account so that the optimal appliances schedule is less sensitive to unpredictable changes in user preferences. The user behavior uncertainty is modeled as uncertainty in the cost function coefficients. In order to reduce the level of conservativeness of the robust solution, we introduce a parameter allowing to achieve a trade-off between the price of robustness and the protection against uncertainty. Mathematically, the robust scheduling problem is posed as a multi-objective Mixed Integer Linear Programming (MILP), which is solved by using standard algorithms. The numerical results show effectiveness of the proposed approach to increase both the electricity bill and $hbox{CO}_{2}$ emissions savings, in the presence of user behavior uncertainties. Mathematical insights into the robust formulation are illustrated and the sensitivity of the optimum cost in the presence of uncertainties is investigated. Although home appliances and EESs are considered in this work, we point out that the proposed scheduling framework is generally applicable to many use cases, e.g., charging and discharging of electrical vehicles in an effective way. In addition, it is applicable to various scenarios considering different uncertainty sources, different storage technologies and generic programmable electrical loads, as well as different optimization criteria.\",\n \"Title: Online fault diagnosis for nonlinear power systems\\nYear: 2015\\n\\nAbstract: This paper considers the problem of automatic fault diagnosis for transmission lines in large scale power networks. Since faults in transmission lines threatens stability of the entire power network, fast and reliable fault diagnosis is an important problem in transmission line protection. This work is the first paper exploiting sparse signal recovery for the fault-diagnosis problem in power networks with nonlinear swing-type dynamics. It presents a novel and scalable technique to detect, isolate and identify transmission faults using a relatively small number of observations by exploiting the sparse nature of the faults. Buses in power networks are typically described by second-order nonlinear swing equations. Based on this description, the problem of fault diagnosis for transmission lines is formulated as a compressive sensing or sparse signal recovery problem, which is then solved using a sparse Bayesian formulation. An iterative reweighted ¿ 1 -minimisation algorithm based on the sparse Bayesian learning update is then derived to solve the fault diagnosis problem efficiently. With the proposed framework, a real-time fault monitoring scheme can be built using only measurements of phase angles at the buses.\",\n \"Title: Distributed Design Of Locally Stabilizing Controllers For Large-Scale Networked Linear Systems\\nYear: 2015\\n\\nAbstract: In this paper, we consider designing locally stabilizing controllers, each of which stabilizes each disconnected subsystem, in a distributed manner for large-scale networked linear systems. To this end, we design a low-dimensional hierarchical distributed compensator such that the L-2-performance of the closed-loop system improves as long as that of the locally stabilizing controllers improves. We solve a controller reduction problem where the approximation error of the low-dimensional compensator gets better as long as the performance of the locally stabilizing controllers improves, while preserving the hierarchical distributed structure of the original compensator. Finally, we demonstrate the efficiency of the proposed method through a numerical example of a power network.\",\n \"Title: Strategic stealthy attacks: The output-to-output ℓ2-gain.\\nYear: 2015\\n\\nAbstract: In this paper, we characterize and analyze the set of strategic stealthy false-data injection attacks on discrete-time linear systems. In particular, the threat scenarios tackled in the paper consider adversaries that aim at deteriorating the systemu0027s performance by maximizing the corresponding quadratic cost function, while remaining stealthy with respect to anomaly detectors. As opposed to other work in the literature, the effect of the adversaryu0027s actions on the anomaly detectoru0027s output is not constrained to be zero at all times. Moreover, scenarios where the adversary has uncertain model knowledge are also addressed. The set of strategic attack policies is formulated as a non-convex constrained optimization problem, leading to a sensitivity metric denoted as the output-to-output l2-gain. Using the framework of dissipative systems, the output-to-output gain is computed through an equivalent convex optimization problem. Additionally, we derive necessary and sufficient conditions for the output-to-output gain to be unbounded, with and without model uncertainties, which are tightly related to the invariant zeros of the system.\",\n \"Title: From control system security indices to attack identifiability\\nYear: 2016\\n\\nAbstract: In this paper, we investigate detectability and identifiability of attacks on linear dynamical systems that are subjected to external disturbances. We generalize a concept for a security index, which was previously introduced for static systems. The index exactly quantifies the resources necessary for targeted attacks to be undetectable and unidentifiable in the presence of disturbances. This information is useful for both risk assessment and for the design of anomaly detectors. Finally, we show how techniques from the fault detection literature can be used to decouple disturbances and to identify attacks, under certain sparsity constraints.\",\n \"Title: Cyber-Physical-Security Framework for Building Energy Management System.\\nYear: 2016\\n\\nAbstract: Energy management systems (EMS) are used to control energy usage in buildings and campuses, by employing technologies such as supervisory control and data acquisition (SCADA) and building management systems (BMS), in order to provide reliable energy supply and maximise user comfort while minimising energy usage. Historically, EMS systems were installed when potential security threats were only physical. Nowadays, EMS systems are connected to the building network and as a result directly to the outside world. This extends the attack surface to potential sophisticated cyber-attacks, which adversely impact EMS operation, resulting in service interruption and downstream financial implications. Currently, the security systems that detect attacks operate independently to those which deploy resiliency policies and use very basic methods. We propose a novel EMS cyber-physical-security framework that executes a resilient policy whenever an attack is detected using security analytics. In this framework, both the resilient policy and the security analytics are driven by EMS data, where the physical correlations between the data-points are identified to detect outliers and then the control loop is closed using an estimated value in place of the outlier. The framework has been tested using a reduced order model of a real EMS site.\",\n \"Title: Clustering-Based Model Reduction of Networked Passive Systems.\\nYear: 2016\\n\\nAbstract: The model reduction problem for networks of interconnected dynamical systems is studied in this paper. In particular, networks of identical passive subsystems, which are coupled according to a tree topology, are considered. For such networked systems, reduction is performed by clustering subsystems that show similar behavior and subsequently aggregating their states, leading to a reduced-order networked system that allows for an insightful physical interpretation. The clusters are chosen on the basis of the analysis of controllability and observability properties of associated edge systems, representing the importance of the couplings and providing a measure of the similarity of the behavior of neighboring subsystems. This reduction procedure is shown to preserve synchronization properties (i.e., the convergence of the subsystem trajectories to each other) and allows for the a priori computation of a bound on the reduction error with respect to external inputs and outputs. The method is illustrated by means of an example of a thermal model of a building.\",\n \"Title: Optimal State Estimation With Measurements Corrupted By Laplace Noise\\nYear: 2016\\n\\nAbstract: Optimal state estimation for linear discrete-time systems is considered. Motivated by the literature on differential privacy, the measurements are assumed to be corrupted by Laplace noise. The optimal least mean square error estimate of the state is approximated using a randomized method. The method relies on that the Laplace noise can be rewritten as Gaussian noise scaled by Rayleigh random variable. The probability of the event that the distance between the approximation and the best estimate is smaller than a constant is determined as function of the number of parallel Kalman filters that is used in the randomized method. This estimator is then compared with the optimal linear estimator, the maximum a posteriori (MAP) estimate of the state, and the particle filter.\",\n \"Title: Limiting the Impact of Stealthy Attacks on Industrial Control Systems.\\nYear: 2016\\n\\nAbstract: While attacks on information systems have for most practical purposes binary outcomes (information was manipulated/eavesdropped, or not), attacks manipulating the sensor or control signals of Industrial Control Systems (ICS) can be tuned by the attacker to cause a continuous spectrum in damages. Attackers that want to remain undetected can attempt to hide their manipulation of the system by following closely the expected behavior of the system, while injecting just enough false information at each time step to achieve their goals. In this work, we study if attack-detection can limit the impact of such stealthy attacks. We start with a comprehensive review of related work on attack detection schemes in the security and control systems community. We then show that many of those works use detection schemes that are not limiting the impact of stealthy attacks. We propose a new metric to measure the impact of stealthy attacks and how they relate to our selection on an upper bound on false alarms. We finally show that the impact of such attacks can be mitigated in several cases by the proper combination and configuration of detection schemes. We demonstrate the effectiveness of our algorithms through simulations and experiments using real ICS testbeds and real ICS systems.\",\n \"Title: Distributed Design of Distributed Control Systems: A Compensation Principle for Controller Retrofit.\\nYear: 2016\\n\\nAbstract: This paper develops a distributed design method for distributed control systems using hierarchical state-space expansion. This expansion generates a redundant state-space realization of systems that enables to regard the system state as the superposition of cascade system states. It is shown from the fact that the stabilization problem of cascade systems can be divided into the stabilization of certain so called upstream and downstream subsystems. This paper clarifies that a downstream subsystem controller can be regarded as a preexistent controller that has implemented to ensure the system stability, whereas a upstream subsystem controller can be regarded as a retrofit controller given as an additional controller with a dynamical compensator. To demonstrate the significance of the proposed distributed design, we give two application examples: one on distributed control of a power system and one on distributed control of a vehicle platoon. The examples demonstrate that appropriate determination of parameter matrices in the hierarchical state- space expansion has some practical relevance for distributed design. Numerical simulations on these examples are shown to support the effectiveness of the theoretical developments.\",\n \"Title: D-Stability And Delay-Independent Stability Of Monotone Nonlinear Systems With Max-Separable Lyapunov Functions\\nYear: 2016\\n\\nAbstract: Stability properties of monotone nonlinear systems with max-separable Lyapunov functions are considered in this paper, motivated by the following observations. First, recent results have shown that such Lyapunov functions are guaranteed to exist for asymptotically stable monotone systems on compact sets. Second, it is well-known that, for monotone linear systems, asymptotic stability implies the stronger properties of D-stability and robustness with respect to time-delays. This paper shows that similar properties hold for monotone nonlinear systems that admit max-separable Lyapunov functions. In particular, a notion of D-stability for monotone nonlinear systems and delay-independent stability will be discussed. The theoretical results are illustrated by means of examples.\",\n \"Title: Secure Estimation For Unstable Systems\\nYear: 2016\\n\\nAbstract: We assume that the states of an unstable dynamical system are encoded and sent to an estimator through an uncertain channel, which is a channel disturbing its inputs in a nonstochastic manner. The encoder's codeword is also fed into another uncertain channel, at whose output an eavesdropper is listening. The estimator should obtain a uniformly bounded system state estimation error, whereas the eavesdropper's information about the system states should be subject to a security constraint. We find a condition on the relation between the uncertain channel from encoder to estimator and the uncertain channel from encoder to eavesdropper which if satisfied allows for at least one of the two following security criteria to hold: The volume of the set of states possible acccording to the eavesdropper's information tends to infinity at exponential speed-by itself (strong security) or if divided by the volume of the set of states possible according to the estimator's information (weak security).\",\n \"Title: Directed Information as Privacy Measure in Cloud-based Control.\\nYear: 2017\\n\\nAbstract: We consider cloud-based control scenarios in which clients with local control tasks outsource their computational or physical duties to a cloud service provider. In order to address concerns in such a control architecture, we first investigate the issue of finding an appropriate measure for clients who desire to keep local state information as private as possible during the control operation. Specifically, we justify the use of Krameru0027s notion of causally conditioned directed information as a measure of loss based on an axiomatic argument. Then we propose a methodology to design an optimal privacy that minimizes loss while a given level of control performance is guaranteed. We show in particular that the optimal filter for cloud-based Linear-Quadratic-Gaussian (LQG) control can be synthesized by a Linear-Matrix-Inequality (LMI) algorithm. The trade-off in the design is illustrated by a numerical example.\",\n \"Title: On the Coherence of Large-Scale Networks With Distributed PI and PD Control.\\nYear: 2017\\n\\nAbstract: We consider distributed control of double-integrator networks, where agents are subject to stochastic disturbances. We study performance of such networks in terms of coherence, defined through an '1i2 norm metric that represents the variance of nodal state fluctuations. Specifically, we address known performance limitations of the standard consensus protocol, which cause this variance to scale unb...\",\n \"Title: Performance And Scalability Of Voltage Controllers In Multi-Terminal Hvdc Networks\\nYear: 2017\\n\\nAbstract: In this paper, we compare the transient performance of a multi-terminal high-voltage DC (MTDC) grid equipped with a slack bus for voltage control to that of two distributed control schemes: a standard droop controller and a distributed averaging proportional-integral (DAPI) controller. We evaluate performance in terms of an H-2 metric that quantifies expected deviations from nominal voltages, and show that the transient performance of a droop or DAPI controlled MTDC grid is always superior to that of an MTDC grid with a slack bus. In particular, by studying systems built up over lattice networks, we show that the H-2 norm of a slack bus controlled system may scale unboundedly with network size, while the norm remains uniformly bounded with droop or DAPI control. We simulate the control strategies on radial MTDC networks to demonstrate that the transient performance for the slack bus controlled system deteriorates significantly as the network grows, which is not the case with the distributed control strategies.\",\n \"Title: Directed Information And Privacy Loss In Cloud-Based Control\\nYear: 2017\\n\\nAbstract: We consider a cloud-based control framework in which individual clients own their local plants that must be controlled by a public authority. Individual clients desire to keep the local state information as private as possible, as long as the cloud-based controller can provide a given level of quality of service. Based on an axiomatic argument, we show that Kramer's notion of causally conditioned directed information from the state random variable to a random variable disclosed to the public authority is an appropriate measure of privacy loss. For a special case with the Linear-Quadratic-Gaussian (LQG) setting, we provide a procedure to construct a \\\"privacy filter\\\" that attains the optimal trade-off between privacy loss and control quality.\",\n \"Title: Guest Editorial Distributed Control and Efficient Optimization Methods for Smart Grid.\\nYear: 2017\\n\\nAbstract: Smart grid proactively uses the state-of-the-art technologies in communications, computing, and control to improve efficiency, reliability, sustainability, and stability of the electrical grid. In particular, distribution networks are expected to undergo dramatic changes by incorporating a large number of sensors and thousands of controllable devices such as distributed generators, batteries and f...\",\n \"Title: A Survey of Distributed Optimization and Control Algorithms for Electric Power Systems.\\nYear: 2017\\n\\nAbstract: Historically, centrally computed algorithms have been the primary means of power system optimization and control. With increasing penetrations of distributed energy resources requiring optimization and control of power systems with many controllable devices, distributed algorithms have been the subject of significant research interest. This paper surveys the literature of distributed algorithms wi...\",\n \"Title: The interconnection of quadratic droop voltage controllers is a Lotka-Volterra system: implications for stability analysis.\\nYear: 2018\\n\\nAbstract: This letter studies the stability of voltage dynamics for a power network in which nodal voltages are controlled by means of quadratic droop controllers with nonlinear AC reactive power as inputs. We show that the voltage dynamics is a Lotka-Volterra system, which is a class of nonlinear positive systems. We study the stability of the closed-loop system by proving a uniform ultimate boundedness re...\",\n \"Title: Exploiting Submodularity in Security Measure Allocation for Industrial Control Systems.\\nYear: 2017\\n\\nAbstract: Industrial control systems are cyber-physical systems that are used to operate critical infrastructures such as smart grids, traffic systems, industrial facilities, and water distribution networks. The digitalization of these systems increases their efficiency and decreases their cost of operation, but also makes them more vulnerable to cyber-attacks. In order to protect industrial control systems from cyber-attacks, the installation of multiple layers of security measures is necessary. In this paper, we study how to allocate a large number of security measures under a limited budget, such as to minimize the total risk of cyber-attacks. The security measure allocation problem formulated in this way is a combinatorial optimization problem subject to a knapsack (budget) constraint. The formulated problem is NP-hard, therefore we propose a method to exploit submodularity of the objective function so that polynomial time algorithms can be applied to obtain solutions with guaranteed approximation bounds. The problem formulation requires a preprocessing step in which attack scenarios are selected, and impacts and likelihoods of these scenarios are estimated. We discuss how the proposed method can be applied in practice.\",\n \"Title: Coherence In Synchronizing Power Networks With Distributed Integral Control\\nYear: 2017\\n\\nAbstract: We consider frequency control of synchronous generator networks and study transient performance under both primary and secondary frequency control. We model random step changes in power loads and evaluate performance in terms of expected deviations from a synchronous frequency over the synchronization transient; what can be thought of as lack of frequency coherence. We compare a standard droop control strategy to two secondary proportional integral (PI) controllers: centralized averaging PI control (CAPI) and distributed averaging PI control (DAPI). We show that the performance of a power system with DAPI control is always superior to that of a CAPI controlled system, which in turn has the same transient performance as standard droop control. Furthermore, for a large class of network graphs, performance scales unfavorably with network size with CAPI and droop control, which is not the case with DAPI control. We discuss optimal tuning of the DAPI controller and describe how internodal alignment of the integral states affects performance. Our results are demonstrated through simulations of the Nordic power grid.\",\n \"Title: Optimal Privacy-Preserving Policy Using Constrained Additive Noise To Minimize The Fisher Information\\nYear: 2017\\n\\nAbstract: The problem of preserving the privacy of individual entries of a database with constrained additive noise is considered. An adversary can submit linear queries to an agent possessing the entire database. The agent returns a response to the query that is corrupted by an additive random noise whose support is a subset or equal to a constraint set. The Cramer-Rao bound is used to bound the variance of the estimation error of the database, which may be used by the adversary, to the trace of the inverse of the Fisher information matrix. A measure of privacy using the Fisher information matrix is developed. The probability density that minimizes the Fisher information (as a proxy for maximizing the measure of privacy) is computed.\",\n \"Title: Glocal Control For Network Systems Via Hierarchical State-Space Expansion\\nYear: 2017\\n\\nAbstract: In this paper, we propose a glocal (global/local) control method for large-scale network systems. The objective of the glocal control here is to suppress global propagation of a disturbance injected at a local subsystem based on the integration of different types of controllers, called global and local controllers. For the design of global and local controllers, we construct an aggregated model and a truncated model that can, respectively, capture global average behavior and local subsystem behavior of the network system of interest. Based on state-space expansion, called hierarchical state-space expansion, we show that a cascade interconnection of the aggregated model and the truncated model can be seen as a low-dimensional approximate model of the original network system, which has good compatibility with independent design of the global and local controllers. Furthermore, we show that appropriate integration of the global and local controllers can improve control performance with respect to global propagation of local disturbance. Finally, the effectiveness of the proposed method is shown through a numerical example of a benchmark model representing the bulk power system in the eastern half of Japan.\",\n \"Title: Wireless Sensor Network Scheduling For Remote Estimation Under Energy Constraints\\nYear: 2017\\n\\nAbstract: This paper studies a design problem of how a group of wireless sensors are selected and scheduled to transmit data efficiently over a multi-hop network subject to energy-saving consideration, when they are observing multiple independent discrete-time linear systems. Each time instant, some sensors are selected to transmit their measurements to a remote estimator. We formulate an optimization problem, minimizing a linear combination of the averaged estimation error and the averaged transmission energy consumption to obtain suitable network scheduling and estimation algorithms. Necessary conditions for optimality are derived and these conditions help trim the feasible solution space so that the optimal solution can be computed efficiently. A numerical example is provided to demonstrate the theoretical results.\",\n \"Title: A Framework for Attack-Resilient Industrial Control Systems: Attack Detection and Controller Reconfiguration.\\nYear: 2018\\n\\nAbstract: Most existing industrial control systems (ICSs), such as building energy management systems (EMSs), were installed when potential security threats were only physical. With advances in connectivity, ICSs are now, typically, connected to communications networks and, as a result, can be accessed remotely. This extends the attack surface to include the potential for sophisticated cyber attacks, which ...\",\n \"Title: A Security Index for Actuators Based on Perfect Undetectability: Properties and Approximation.\\nYear: 2018\\n\\nAbstract: A novel security index based on the definition of perfect undetectability is proposed. The index is a tool that can help a control system operator to localize the most vulnerable actuators in the network. In particular, the security index of actuator i represents the minimal number of sensors and actuators that needs to be compromised in addition to i, such that a perfectly undetectable attack is possible. A method for computing this index for small scale systems is derived, and difficulties with the index once the system is of large scale are outlined. An upper bound for the index that overcomes these difficulties is then proposed. The theoretical developments are illustrated on a numerical example.\",\n \"Title: Anomaly Detector Metrics for Sensor Data Attacks in Control Systems\\nYear: 2018\\n\\nAbstract: We investigate worst-case impacts of stealthy full sensor attacks against linear control systems under a general class of anomaly detectors. We show that the worst-case impact scales with a parameter that is solely determined by the number of sensors in the plant, the detector used, and its tuning. Therefore, we obtain a general metric to compare the performance of detectors of this class of detectors under the investigated sensor attack, which is independent of the plant dynamics and applies to all linear systems with the same number of sensors.\",\n \"Title: Optimization Of The H-Infinity-Norm Of Dynamic Flow Networks\\nYear: 2018\\n\\nAbstract: In this paper, we study the H-infinity-norm of linear systems over graphs, which is used to model distribution networks. In particular, we aim to minimize the H-infinity-norm subject to allocation of the weights on the edges. The optimization problem is formulated with LMI (Linear-Matrix Inequality) constraints. For distribution networks with one port, i.e., SISO systems, we show that the H-infinity-norm coincides with the effective resistance between the nodes in the port. Moreover, we derive an upper bound of the H-infinity-norm, which is in terms of the algebraic connectivity of the graph on which the distribution network is defined.\",\n \"Title: Performance Limitations Of Distributed Integral Control In Power Networks Under Noisy Measurements\\nYear: 2018\\n\\nAbstract: Distributed approaches to secondary frequency control have become a way to address the need for more flexible control schemes in power networks with increasingly distributed generation. The distributed averaging proportional-integral (DAPI) controller presents one such approach. In this paper, we analyze the transient performance of this controller, and specifically address the question of its performance under noisy frequency measurements. Performance is analyzed in terms of an H-2 norm metric that quantifies power losses incurred in the synchronization transient. While previous studies have shown that the DAPI controller performs well, in particular in sparse networks and compared to a centralized averaging PI (CAPI) controller, our results prove that additive measurement noise may have a significant negative impact on its performance and scalability. This impact is shown to decrease with an increased inter-nodal alignment of the controllers' integral states, either through increased gains or increased connectivity. For very large and sparse networks, however, the requirement for inter-nodal alignment is so large that a CAPI approach may be preferable. Overall, our results show that distributed secondary frequency control through DAPI is possible and may perform well also under noisy measurements, but requires careful tuning.\",\n \"Title: Retrofit control: Localization of controller design and implementation.\\nYear: 2018\\n\\nAbstract: In this paper, we propose a retrofit control method for stable network systems. The proposed approach is a control method that, rather than an entire system model, requires a model of the subsystem of interest for controller design. To design the retrofit controller, we use a novel approach based on hierarchical state-space expansion that generates a higher-dimensional cascade realization of a given network system. The upstream dynamics of the cascade realization corresponds to an isolated model of the subsystem of interest, which is stabilized by a local controller. The downstream dynamics can be seen as a dynamical model representing the propagation of interference signals among subsystems, the stability of which is equivalent to that of the original system. This cascade structure enables a systematic analysis of both the stability and control performance of the resultant closed-loop system. The resultant retrofit controller is formed as a cascade interconnection of the local controller and an output rectifier that rectifies an output signal of the subsystem of interest so as to conform to an output signal of the isolated subsystem model while acquiring complementary signals neglected in the local controller design, such as interconnection signals from neighboring subsystems. Finally, the efficiency of the retrofit control method is demonstrated through numerical examples of power systems control and vehicle platoon control.\",\n \"Title: A Survey of Physics-Based Attack Detection in Cyber-Physical Systems.\\nYear: 2018\\n\\nAbstract: Monitoring the \\\"physics\\\" of cyber-physical systems to detect attacks is a growing area of research. In its basic form a security monitor creates time-series models of sensor readings for an industrial control system and identifies anomalies in these measurements in order to identify potentially false control commands or false sensor readings. In this paper, we review previous work on physics-based anomaly detection based on a unified taxonomy that allows us to identify limitations and unexplored challenges, and propose new solutions.\",\n \"Title: Ensuring Privacy with Constrained Additive Noise by Minimizing Fisher Information.\\nYear: 2019\\n\\nAbstract: The problem of preserving the privacy of individual entries of a database when responding to linear or nonlinear queries with constrained additive noise is considered. For privacy protection, the response to the query is systematically corrupted with an additive random noise whose support is a subset or equal to a pre-defined constraint set. A measure of privacy using the inverse of the trace of the Fisher information matrix is developed. The Cramér–Rao bound relates the variance of any estimator of the database entries to the introduced privacy measure. The probability density that minimizes the trace of the Fisher information (as a proxy for maximizing the measure of privacy) is computed. An extension to dynamic problems is also presented. Finally, the results are compared to the differential privacy methodology.\",\n \"Title: Synchronization Of Kuramoto Oscillators In A Bidirectional Frequency-Dependent Tree Network\\nYear: 2018\\n\\nAbstract: This paper studies the synchronization of a finite number of Kuramoto oscillators in a frequency-dependent bidirectional tree network. We assume that the coupling strength of each link in each direction is equal to the product of a common coefficient and the exogenous frequency of its corresponding source oscillator. We derive a sufficient condition for the common coupling strength in order to guarantee frequency synchronization in tree networks. Moreover, we discuss the dependency of the obtained bound on both the graph structure and the way that exogenous frequencies are distributed. Further, we present an application of the obtained result by means of an event-triggered algorithm for achieving frequency synchronization in a star network assuming that the common coupling coefficient is given.\",\n \"Title: Large Scale Rollout of Smart Grid Services\\nYear: 2018\\n\\nAbstract: In the domain of energy automation, where a massive number of software-based IoT services interact with a complex dynamic system, processes for software installation and software update become more important and more complex. These processes have to ensure that the dependencies on all layers are fulfilled, including dependencies arising due to the energy system controlled by IT components being a hidden communication channel between these components. In addition, the processes have to be resilient against faults in and attacks to both the energy grid and the communication network. The ERA-Net funded project LarGo! aims at developing and testing processes for the large scale rollout of software applications in the power grid domain as well as the user domain. This article describes a work in progress and the project's roadmap to solve the technical issues. It investigates the problems that arise from the interlocking of the two networks- the power grid and the communication network. Based on this analysis a first set of requirements for a rollout process in such a Smart Grid is derived and the chosen approach to verify the resilience of the developed processes under research is described.\",\n \"Title: Estimating the Impact of Cyber-Attack Strategies for Stochastic Control Systems.\\nYear: 2018\\n\\nAbstract: Risk assessment is an inevitable step in implementation of a cyber-defense strategy. An important part of this assessment is to reason about the impact of possible attacks. In this paper, we study the problem of estimating the impact of cyber-attacks in stochastic linear networked control systems. For the stealthiness constraint, we adopt the Kullback–Leibler divergence between attacked and nonatt...\",\n \"Title: Quantifying the Impact of Cyber-Attack Strategies for Control Systems Equipped With an Anomaly Detector\\nYear: 2018\\n\\nAbstract: Risk assessment is an inevitable step in the implementation of cost-effective security strategies for control systems. One of the difficulties of risk assessment is to estimate the impact cyber-attacks may have. This paper proposes a framework to estimate the impact of several cyber-attack strategies against a dynamical control system equipped with an anomaly detector. In particular, we consider denial of service, sign alternation, rerouting, replay, false data injection, and bias injection attack strategies. The anomaly detectors we consider are stateless, cumulative sum, and multivariate exponentially weighted moving average detectors. As a measure of the attack impact, we adopt the infinity norm of critical states after a fixed number of time steps. For this measure and the aforementioned anomaly detectors, we prove that the attack impact for all of the attack strategies can be reduced to the problem of solving a set of convex minimization problems. Therefore, the exact value of the attack impact can be obtained easily. We demonstrate how our modeling framework can be used for risk assessment on a numerical example.\",\n \"Title: Asymptotic And Finite-Time Almost Global Attitude Tracking: Representations Free Approach\\nYear: 2018\\n\\nAbstract: In this paper, the attitude tracking problem is considered using the rotation matrices. Due to the inherent topological restriction, it is impossible to achieve global attractivity with any continuous attitude control system on SO(3). Hence in this work, we propose some control protocols achieving almost global tracking asymptotically and in finite time, respectively. In these protocols, no world frame is needed and only relative state information are requested. For finite-time tracking case, Filippov solutions and non-smooth analysis techniques are adopted to handle the discontinuities. Simulation examples are provided to verify the performances of the control protocols designed in this paper.\",\n \"Title: Secure Patching Of An Output-Feedback Controller For A Class Of Nonlinear Systems Under Adversarial Attack\\nYear: 2018\\n\\nAbstract: We consider a class of nonlinear systems for which an observer-based output-feedback controller is updated at discrete time instances. However, the received update or patch can be compromised by the attacker to drive the system to instability. In this paper, we provide a checkable condition to ensure that the received patch has not been tampered with to cause instability in the control system. Moreover, we guarantee that the application of the tamper-free patch ensures global asymptotic stability of the control system by choosing the update time instances appropriately. The secure patch update protocol is illustrated on an example involving the output-feedback synchronization of two neuron population models, where the observer gains are updated at discrete time instances.\",\n \"Title: A Risk-Theoretical Approach To H-2-Optimal Control Under Covert Attacks\\nYear: 2018\\n\\nAbstract: We consider the control design problem of optimizing the H-2 performance of a closed-loop system despite the presence of a malicious covert attacker. It is assumed that the attacker has incomplete knowledge on the true process we are controlling. To account for this uncertainty, we employ different measures of risk from the so called family of coherent measures of risk. In particular, we compare the closed-loop performance when a nominal value is used, with three different measures of risk: average risk, worst-case scenario and conditional valueat- risk (CVaR). Additionally, applying the approach from a previous work, we derive a convex formulation for the control design problem when CVaR is employed to quantify the risk. A numerical example illustrates the advantages of our approach.\",\n \"Title: A Game-Theoretic Approach For Choosing A Detector Tuning Under Stealthy Sensor Data Attacks\\nYear: 2018\\n\\nAbstract: A Stackelberg game framework is presented to choose the detector tuning for a general detector class under stealthy sensor attacks. In this framework, the defender acts as a leader and chooses a detector tuning, while the attacker will follow with a stealthy attack adjusted to this tuning. The tuning chosen is optimal with respect to the cost induced by the false alarms and the attack impact. We can show that under some practical assumptions the Stackelberg game always has a solution and we state two different sufficient conditions for the uniqueness of the solution. Interestingly, these conditions show that the attack impact does not have to be a convex function. An illustrative attack scenario of a false-data injection attack shows how one can use the Stackelberg game to find the optimal detector tuning.\",\n \"Title: Two-Way Coding in Control Systems Under Injection Attacks: From Attack Detection to Attack Correction.\\nYear: 2019\\n\\nAbstract: In this paper, we introduce the method of two-way coding, a concept originating in communication theory characterizing coding schemes for two-way channels, into (networked) feedback control systems under injection attacks. We first show that the presence of two-way coding can distort the perspective of the attacker on the control system. In general, the distorted viewpoint on the attacker side as a consequence of two-way coding will facilitate detecting the attacks, or restricting what the attacker can do, or even correcting the attack effect. In the particular case of zero-dynamics attacks, if the attacks are to be designed according to the original plant, then they will be easily detected; while if the attacks are designed with respect to the equivalent plant as viewed by the attacker, then under the additional assumption that the plant is stabilizable by static output feedback, the attack effect may be corrected in steady state.\",\n \"Title: A Study On The Sensitivity Matrix In Power System State Estimation By Using Sparse Principal Component Analysis\\nYear: 2016\\n\\nAbstract: This paper analyzes the joint impact of uncertainties in the input data on the power system state estimator. The approach is based on the sensitivity analysis of the estimated telemetry data with respect to the measurement data and the branch parameters with the main goal of locating relevant input components. In order to find relevant inputs, we analyze the normalized sensitivity matrix by sparse principal component analysis (PCA). The non-zero entries of the loading vectors related to the dominant principal components are considered to be the relevant inputs to the state estimator as they mainly contribute to the amplification of the estimated values. It turns out that PCA shows an elementary structure of the sensitivity matrix: All non-zero entries of a loading vector corresponding to a positive singular value belong either to the telemetry data or to the branch data. We show that this property is also valid for PCA with different sparsity-promoting constraints on the loading vector. The proposed analysis method is demonstrated by a numerical study.\",\n \"Title: Retrofitting State Feedback Control Of Networked Nonlinear Systems Based On Hierarchical Expansion\\nYear: 2016\\n\\nAbstract: In this paper, we propose a systematic method to design retrofit controllers for networked nonlinear systems. The retrofit controller, which consists of a linear state feedback controller and a dynamical compensator, can improve the control performance for a subsystem of interest, while guaranteeing the stability of the whole closed-loop system. Towards the retrofit controller design, we introduce a type of state-space expansion, called hierarchical expansion. The cascade structure of the hierarchical expansion realization enables the systematic design of a stabilizing controller for a low-dimensional linear model extracted from the subsystem of interest. As a result, we can design a retrofit controller without explicit consideration of the dynamics of subsystems other than the subsystem of interest. The effectiveness of the proposed method is demonstrated through a power network example.\",\n \"Title: Security Analysis Of Control System Anomaly Detectors\\nYear: 2017\\n\\nAbstract: Two anomaly detectors for control systems are analyzed with respect to their sensitivity to malicious data injection attacks. A stateless anomaly detector based on the current residual signal is compared to a cumulative sum detector. The worst-case impact of a stealthy time-limited data injection attack is characterized for both detectors by a non-convex optimization problem and compared to determine which detector limits the impact the most. We prove that the problem can be solved by means of a set of convex optimization problems. Simulations verify that finding the right configuration for the cumulative sum is crucial to limit the worst-case attack impact more than with a stateless anomaly detector.\",\n \"Title: Distributed Sensor and Actuator Reconfiguration for Fault-Tolerant Networked Control Systems.\\nYear: 2018\\n\\nAbstract: In this paper, we address the problem of distributed reconfiguration of networked control systems upon the removal of misbehaving sensors and actuators. In particular, we consider systems with redundant sensors and actuators cooperating to recover from faults. Reconfiguration is performed while minimizing a steady-state estimation error covariance and quadratic control cost. A model-matching condi...\",\n \"Title: Noise-induced limitations to the scalability of distributed integral control\\nYear: 2019\\n\\nAbstract: We study performance limitations of distributed feedback control in large-scale networked dynamical systems. Specifically, we address the question of how the performance of distributed integral control is affected by measurement noise. We consider second-order consensus-like problems modeled over a toric lattice network, and study asymptotic scalings (in network size) of H2 performance metrics that quantify the variance of nodal state fluctuations. While previous studies have shown that distributed integral control fundamentally improves these performance scalings compared to distributed proportional feedback control, our results show that an explicit inclusion of measurement noise leads to the opposite conclusion. The noise’s impact on performance is shown to decrease with an increased inter-nodal alignment of the local integral states. However, even though the controller can be tuned for acceptable performance for any given network size, performance will degrade as the network grows, limiting the scalability of any such controller tuning. In particular, the requirement for inter-nodal alignment increases with network size. We show that this may in practice imply that very large and sparse networks will require any integral control to be centralized, rather than distributed. In this case, the best-achievable performance scaling, which is shown to be that of proportional feedback control, is retrieved.\",\n \"Title: A Graph-Theoretic Approach to the ℋ Performance of Leader-Follower Consensus on Directed Networks.\\nYear: 2019\\n\\nAbstract: We study a graph-theoretic approach to the H∞ performance of leader following consensus dynamics in the presence of external disturbances when the underlying graph is a directed network. We first provide graph-theoretic necessary and sufficient conditions for the consensus dynamics to have the system H∞ norm from external disturbances to the state of each agent to be lower than a certain value. Mo...\",\n \"Title: Sample-based anomaly detector tuning with finite sample guarantees\\nYear: 2021\\n\\nAbstract: We present a sample-based approach for tuning an anomaly detector threshold to achieve an acceptable false alarm rate without a priori knowledge of system or detector dynamics. If the distribution of the output of the detector is known, finding such a threshold can be re-interpreted as determining a specific quantile of the detector output distribution, which is the minimizer of a convex optimization problem. The sample-based approach we propose approximates the threshold from the empirical distribution. We, further, identify distribution free finite sample guarantees that give the number of samples required to ensure the false alarm rate is near the acceptable value. Finally, we numerically verify our approach on both static and dynamic anomaly detectors, where we investigate both light- and heavy-tailed distributions.\",\n \"Title: Resource Constrained Sensor Attacks by Minimizing Fisher Information\\nYear: 2021\\n\\nAbstract: We analyze the impact of sensor attacks on a linear state estimation problem subject to variance and sparsity constraints. We show that the maximum impact in a leader-follower game where the attacker first chooses the distribution of an adversarial perturbation and the defender follows by choosing an estimator is characterized by a minimum Fisher information principle. In general, this is a nonlinear variational problem, but we show that it can be reduced to a finite-dimensional mixed integer SDP. Alternatively, the proposed solution can be seen as a lower bound on the maximum impact for a game in which the defender plays first.\",\n \"Title: Adversarial Attacks on CFO-Based Continuous Physical Layer Authentication: A Game Theoretic Study\\nYear: 2021\\n\\nAbstract: 5G and beyond 5G low power wireless networks make Internet of Things (IoT) and Cyber-Physical Systems (CPS) applications capable of serving massive amounts of devices and machines. Due to the broadcast nature of wireless networks, it is crucial to secure the communication between these devices and machines from spoofing and interception attacks. This paper is concerned with the security of carrier...\",\n \"Title: Privacy Guarantees for Cloud-based State Estimation using Partially Homomorphic Encryption\\nYear: 2022\\n\\nAbstract: The privacy aspect of state estimation algorithms has been drawing high research attention due to the necessity for a trustworthy private environment in cyber-physical systems. These systems usually engage cloud-computing platforms to aggregate essential information from spatially distributed nodes and produce desired estimates. The exchange of sensitive data among semi-honest parties raises privacy concerns, especially when there are coalitions between parties. We propose two privacy-preserving protocols using Kalman filter and partially homomorphic encryption of the measurements and estimates while exposing the covariances and other model parameters. We prove that the proposed protocols achieve satisfying computational privacy guarantees against various coalitions based on formal cryptographic definitions of indistinguishability. We evaluate the proposed protocols to demonstrate their efficiency using data from a real testbed.\",\n \"Title: Control Theory For Practical Cyber-Physical Security\\nYear: 2018\\n\\nAbstract: In this talk, we discuss how control theory can contribute to the analysis and design of secure cyber-physical systems. We start by reviewing conditions for undetectable false-data injection attacks on feedback control systems. In particular, we highlight how a physical understanding of the controlled process can guide us in the allocation of protective measures. We show that protecting only a few carefully selected actuators or sensors can give indirect protection to many more components. We then illustrate how such analysis is exploited in the design of a resilient control scheme for a microgrid energy management system.\",\n \"Title: Security index based on perfectly undetectable attacks: Graph-theoretic conditions\\nYear: 2021\\n\\nAbstract: The notion of security index quantifies the least effort involved in conducting perfectly undetectable attacks. Thus, the security index enables a systems operator to assess the vulnerability of a component, informs sensor placement strategies, and helps in deciding the feasibility of secure estimators and fault detectors. In this paper, we investigate the (possible) variation in this index as a consequence of variation in the system parameters. To this end, we adopt a structured systems approach, typically represented by a directed graph, with the edges of the said graph being in one-to-one correspondence with the system parameters. We first show that the security index is generic. That is, for almost all choices of edge weights, the security index of a component remains the same. We refer to such an index as the generic security index. Secondly, we derive graph-theoretic conditions (and based on those an algorithm) for computing the generic security index. Third, we provide graph-theoretic conditions for computing lower (resp. upper) bounds on the values that the security index of a component can take for all nonzero choices of the edge weights of the directed graph. Finally, we provide a brute force search method for calculating the said bounds.\",\n \"Title: A Randomized Filtering Strategy Against Inference Attacks on Active Steering Control Systems\\nYear: 2022\\n\\nAbstract: In this paper, we develop a framework against inference attacks aimed at inferring the values of the controller gains of an active steering control system (ASCS). We first show that an adversary with access to the shared information by a vehicle, via a vehicular ad hoc network (VANET), can reliably infer the values of the controller gains of an ASCS. This vulnerability may expose the driver as wel...\",\n \"Title: Single Trajectory Nonparametric Learning of Nonlinear Dynamics.\\nYear: 2022\\n\\nAbstract: Given a single trajectory of a dynamical system, we analyze the performance of the nonparametric least squares estimator (LSE). More precisely, we give nonasymptotic expected $l^2$-distance bounds between the LSE and the true regression function, where expectation is evaluated on a fresh, counterfactual, trajectory. We leverage recently developed information-theoretic methods to establish the optimality of the LSE for nonparametric hypotheses classes in terms of supremum norm metric entropy and a subgaussian parameter. Next, we relate this subgaussian parameter to the stability of the underlying process using notions from dynamical systems theory. When combined, these developments lead to rate-optimal error bounds that scale as $T^{-1/(2+q)}$ for suitably stable processes and hypothesis classes with metric entropy growth of order $\\\\delta^{-q}$. Here, $T$ is the length of the observed trajectory, $\\\\delta \\\\in \\\\mathbb{R}_+$ is the packing granularity and $q\\\\in (0,2)$ is a complexity term. Finally, we specialize our results to a number of scenarios of practical interest, such as Lipschitz dynamics, generalized linear models, and dynamics described by functions in certain classes of Reproducing Kernel Hilbert Spaces (RKHS).\",\n \"Title: Leakage Localization in Water Distribution Networks: A Model-Based Approach\\nYear: 2022\\n\\nAbstract: The paper studies the problem of leakage localization in water distribution networks. For the case of a single pipe that suffers from a single leak, by taking recourse to pressure and flow measurements, and assuming those are noiseless, we provide a closed-form expression for leak localization, leak exponent and leak constant. For the aforementioned setting, but with noisy pressure and flow measurements, an expression for estimating the location of the leak is provided. Finally, assuming the existence of a single leak, for a network comprising of more than one pipe and assuming that the network has a tree structure, we provide a systematic procedure for determining the leak location, the leak exponent, and the leak constant.\",\n \"Title: GEOMETRICAL CHARACTERIZATION OF SENSOR PLACEMENT FOR CONE-INVARIANT AND MULTI-AGENT SYSTEMS AGAINST UNDETECTABLE ZERO-DYNAMICS ATTACKS\\\\ast\\nYear: 2022\\n\\nAbstract: Undetectable attacks are an important class of malicious attacks threatening the security of cyber-physical systems, which can modify a system's state but leave the system output measurements unaffected and hence cannot be detected from the output. This paper studies undetectable attacks on cone-invariant systems and multi-agent systems. We first provide a general characterization of zero-dynamics attacks, which characterizes fully undetectable attacks targeting the nonminimum phase zeros of a system. This geometrical characterization makes it possible to develop a defense strategy seeking to place a minimal number of sensors to detect and counter the zero-dynamics attacks on the system's actuators. The detect and defense scheme amounts to computing a set containing potentially vulnerable actuator locations and nodes and a defense union for feasible placement of sensors based on the geometrical properties of the cones under consideration.\",\n \"Title: Data-injection Attacks Using Historical Inputs and Outputs\\nYear: 2021\\n\\nAbstract: Data-driven, model-free control has become popular in recent years, due to their ease of implementation and minimal information requirement about the system. In this paper, we investigate whether the same methods could be used by an adversary to synthesize undetectable data-injection attacks on cyber-physical systems using Willems' Fundamental Lemma. We show that if the adversary is able to upper bound the order of a linear, time-invariant system and read all its inputs and outputs, then the adversary will be able to generate undetectable attack signals in the form of covert attacks. Additionally, we provide conditions on the disclosed data set that enable the adversary to generate zero dynamics attacks. These conditions give operators insights into when enough information about the system has been revealed for an adversary to conduct an undetectable attack. Finally, the different attack strategies are verified through a numerical example.\",\n \"Title: A Game-Theoretic Framework for Security-Aware Sensor Placement Problem in Networked Control Systems\\nYear: 2022\\n\\nAbstract: This article studies the sensor placement problem in a leader–follower networked control system for improving its security against cyber-physical attacks. In a zero-sum game, the attacker selects \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$f$</tex-math></inline-formula>\\n nodes of the network to attack, and the detector places \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$f$</tex-math></inline-formula>\\n sensors to detect the presence of the attack signals. In our formulation, the attacker’s objective is to have a large impact on a target node in the network while being as little visible as possible to the detector. The detector, however, seeks to maximize the visibility of the attack signals. The effects of the attack signals on both the target node and the detector node are captured via the system \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$L_2$</tex-math></inline-formula>\\n gain from the attack signals to the target node and deployed sensors’ outputs, respectively. The equilibrium strategy of the game determines the optimal locations of the sensors. The existence of Nash equilibrium for the single-attack single-sensor case is studied when the underlying connectivity graph is a directed or an undirected tree. We show that, under the optimal sensor placement strategy, an undirected topology provides a higher security level for a networked control system compared to its corresponding directed topology. For the multiple-attack multiple-sensor case, we show that the game does not necessarily admit a Nash equilibrium and introduce a Stackelberg game approach, where the detector acts as the leader. Finally, these results are used to study the sensor placement problem in a vehicle platooning application in the presence of bias injectionattacks.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":119,"string":"119"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":274,"string":"274"}}},{"rowIdx":275,"cells":{"question_id":{"kind":"string","value":"Masaru Tomita"},"question":{"kind":"string","value":"Generate an abstract for the title \"Particle Simulation of Oxidation Induced Band 3 Clustering in Human Erythrocytes.\" using the following items: 1. Oxidative stress\n2. Band 3 clustering\n3. Red blood cell clearance\n4. Simulation modeling\n5. Antioxidant metabolism"},"answer":{"kind":"string","value":"Oxidative stress mediated clustering ofmembrane protein band 3 plays an essential role in the clearance of damaged and aged red blood cells (RBCs) from the circulation. While a number of previous experimental studies have observed changes in band 3 distribution after oxidative treatment, the details of how these clusters are formed and how their properties change under different conditions have remained poorly understood. To address these issues, a framework that enables the simultaneous monitoring of the temporal and spatial changes following oxidation is needed. In this study, we established a novel simulation strategy that incorporates deterministic and stochastic reactions with particle reaction-diffusion processes, to model band 3 cluster formation at single molecule resolution. By integrating a kinetic model of RBC antioxidant metabolism with a model of band 3 diffusion, we developed a model that reproduces the time-dependent changes of glutathione and clustered band 3 levels, as well as band 3 distribution during oxidative treatment, observed in prior studies. We predicted that cluster formation is largely dependent on fast reverse reaction rates, strong affinity between clustering molecules, and irreversible hemichrome binding. We further predicted that under repeated oxidative perturbations, clusters tended to progressively grow and shift towards an irreversible state. Application of our model to simulate oxidation in RBCs with cytoskeletal deficiency also suggested that oxidation leads to more enhanced clustering compared to healthy RBCs. Taken together, our model enables the prediction of band 3 spatio-temporal profiles under various situations, thus providing valuable insights to potentially aid understanding mechanisms for removing senescent and premature RBCs."},"correct_answer":{"kind":"string","value":"Oxidative stress mediated clustering ofmembrane protein band 3 plays an essential role in the clearance of damaged and aged red blood cells (RBCs) from the circulation. While a number of previous experimental studies have observed changes in band 3 distribution after oxidative treatment, the details of how these clusters are formed and how their properties change under different conditions have remained poorly understood. To address these issues, a framework that enables the simultaneous monitoring of the temporal and spatial changes following oxidation is needed. In this study, we established a novel simulation strategy that incorporates deterministic and stochastic reactions with particle reaction-diffusion processes, to model band 3 cluster formation at single molecule resolution. By integrating a kinetic model of RBC antioxidant metabolism with a model of band 3 diffusion, we developed a model that reproduces the time-dependent changes of glutathione and clustered band 3 levels, as well as band 3 distribution during oxidative treatment, observed in prior studies. We predicted that cluster formation is largely dependent on fast reverse reaction rates, strong affinity between clustering molecules, and irreversible hemichrome binding. We further predicted that under repeated oxidative perturbations, clusters tended to progressively grow and shift towards an irreversible state. Application of our model to simulate oxidation in RBCs with cytoskeletal deficiency also suggested that oxidation leads to more enhanced clustering compared to healthy RBCs. Taken together, our model enables the prediction of band 3 spatio-temporal profiles under various situations, thus providing valuable insights to potentially aid understanding mechanisms for removing senescent and premature RBCs."},"documents":{"kind":"list like","value":["Title: Parsing noisy sentences\nYear: 1988\n\nAbstract: This paper describes a method to parse and understand a \"noisy\" sentence that possibly includes errors caused by a speech recognition device. Our parser is connected to a speech recognition device which takes a continuously spoken sentence in Japanese and produces a sequence of phonemes. The output sequence of phonemes can quite possibly include errors: altered phonemes, extra phonemes and missing phonemes. The task is to parse the noisy phoneme sequence and understand the meaning of the original input sentence, given an augmented context-free grammar whose terminal symbols are phonemes. A very efficient parsing method is required, as the task's search space is much larger than that of parsing un-noisy sentences. We adopt the generalized LR parsing algorithm, and a certain scoring scheme to select the most likely sentence out of multiple sentence candidates. The use of a , which is created in advance by analyzing a large set of input/output pairs, is discussed to improve the scoring accuracy. The system has been integrated into CMU's knowledge-based machine translation system.","Title: MathDAMP: a package for differential analysis of metabolite profiles.\nYear: 2006\n\nAbstract: With the advent of metabolomics as a powerful tool for both functional and biomarker discovery, the identification of specific differences between complex metabolite profiles is becoming a major challenge in the data analysis pipeline. The task remains difficult, given the datasets' size, complexity, and common shifts in migration (elution/retention) times between samples analyzed by hyphenated mass spectrometry methods.We present a Mathematica (Wolfram Research, Inc.) package MathDAMP (Mathematica package for Differential Analysis of Metabolite Profiles), which highlights differences between raw datasets acquired by hyphenated mass spectrometry methods by applying arithmetic operations to all corresponding signal intensities on a datapoint-by-datapoint basis. Peak identification and integration is thus bypassed and the results are displayed graphically. To facilitate direct comparisons, the raw datasets are automatically preprocessed and normalized in terms of both migration times and signal intensities. A combination of dynamic programming and global optimization is used for the alignment of the datasets along the migration time dimension. The processed datasets and the results of direct comparisons between them are visualized using density plots (axes represent migration time and m/z values while peaks appear as color-coded spots) providing an intuitive overall view. Various forms of comparisons and statistical tests can be applied to highlight subtle differences. Overlaid electropherograms (chromatograms) corresponding to the vicinities of the candidate differences from any result may be generated in a descending order of significance for visual confirmation. Additionally, a standard library table (a list of m/z values and migration times for known compounds) may be aligned and overlaid on the plots to allow easier identification of metabolites.Our tool facilitates the visualization and identification of differences between complex metabolite profiles according to various criteria in an automated fashion and is useful for data-driven discovery of biomarkers and functional genomics.","Title: Parsing spoken language: a semantic caseframe approach\nYear: 1986\n\nAbstract: Parsing spoken input introduces serious problems not present in parsing typed natural language. In particular, indeterminacies and inaccuracies of acoustic recognition must be handled in an integral manner. Many techniques for parsing typed natural language do not adapt well to these extra demands. This paper describes an extension of semantic caseframe parsing to restricted-domain spoken input. The semantic caseframe grammar representation is the same as that used for earlier work on robust parsing of typed input. Due to the uncertainty inherent in speech recognition, the caseframe grammar is applied in a quite different way, emphasizing island growing from caseframe headers. This radical change in application is possible due to the high degree of abstraction in the caseframe representation. The approach presented was tested successfully in a preliminary implementation.","Title: Kinetic simulation of signal transduction system in hippocampal long-term potentiation with dynamic modeling of protein phosphatase 2A.\nYear: 2003\n\nAbstract: We modeled and analyzed a signal transduction system of long-term potentiation (LTP) in hippocampal post-synapse. Bhalla and Iyengar [Science 283(1999) 381] have developed a hippocampal LTP model. In the conventional model, the concentration of protein phosphatase 2A (PP2A) was fixed. However, it was reported that dynamic inactivation of PP2A was essential for LTP [J. Neurochem. 74 (2000) 807]. We introduced a dynamic modeling of PP2A; inactivation (phosphorylation) of PP2A by calcium/calmodulin-dependent protein kinase II (CaMKII) in the presence of calcium/calmodulin, self-activation (autodephosphorylation) of PP2A, and inactivation (dephosphorylation) of CaMKII by PP2A. This model includes complex feedback loops; both CaMKII and PP2A are autoactivated, while they inactivate each other. Moreover, we proposed an analysis strategy for model validation by applying the results of sensitivity analysis. In our system, calcineurin (CaN) played an essential role, rather than the activation of protein kinase C (PKC) as documented in the conventional model. From results of the analysis of our model, we found the following robustness as characteristics of bistability in our model: (1). PP2A reactions against calcium ion (Ca(2+)) perturbation; (2). PP2A inactivation against PP2A increase; (3). protein phosphatase 1 (PP1) activation against PF2A increase; and (4). PP2A reactions against PP2A initial concentration. These properties facilitated LTP induction in our system. We showed that another mechanism could introduce bistable behavior by adding dynamic reactions of PP2A.","Title: Distributed cell biology simulations with e-cell system\nYear: 2004\n\nAbstract: Many useful applications of simulation in computational cell biology, e.g. kinetic parameter estimation, Metabolic Control Analysis (MCA), and bifurcation analysis, require a large number of repetitive runs with different input parameters. The heavy requirements imposed by these analysis methods on computational resources has led to an increased interest in parallel- and distributed computing technologies. We have developed a scripting environment that can execute, and where possible, automatically parallelize those mathematical analysis sessions transparently on any of (1) single-processor workstations, (2) Shared-memory Multiprocessor (SMP) servers, (3) workstation clusters, and (4) computational grid environments. This computational framework, E-Cell SessionManager (ESM), is built upon E-Cell System Version 3, a generic software environment for the modeling, simulation, and analysis of whole-cell scale biological systems. Here we introduce the ESM architecture and provide results from benchmark experiments that addressed 2 typical computationally intensive biological problems, (1) a parameter estimation session of a small hypothetical pathway and (2) simulations of a stochastic E. coli heat-shock model with different random number seeds to obtain the statistical characteristics of the stochastic fluctuations.","Title: HybGFS: a hybrid method for genome-fingerprint scanning.\nYear: 2006\n\nAbstract: Protein identification based on mass spectrometry (MS) has previously been performed using peptide mass fingerprinting (PMF) or tandem MS (MS/MS) database searching. However, these methods cannot identify proteins that are not already listed in existing databases. Moreover, the alternative approach of de novo sequencing requires costly equipment and the interpretation of complex MS/MS spectra. Thus, there is a need for novel high-throughput protein-identification methods that are independent of existing predefined protein databases.Here, we present a hybrid method for genome-fingerprint scanning, known as HybGFS. This technique combines genome sequence-based peptide MS/MS ion searching with liquid-chromatography elution-time (LC-ET) prediction, to improve the reliability of identification. The hybrid method allows the simultaneous identification and mapping of proteins without a priori information about their coding sequences. The current study used standard LC-MS/MS data to query an in silico-generated six-reading-frame translation and the enzymatic digest of an entire genome. Used in conjunction with precursor/product ion-mass searching, the LC-ETs increased confidence in the peptide-identification process and reduced the number of false-positive matches. The power of this method was demonstrated using recombinant proteins from the Escherichia coli K12 strain.The novel hybrid method described in this study will be useful for the large-scale experimental confirmation of genome coding sequences, without the need for transcriptome-level expression analysis or costly MS database searching.","Title: Towards the systematic discovery of signal transduction networks using phosphorylation dynamics data.\nYear: 2010\n\nAbstract: Phosphorylation is a ubiquitous and fundamental regulatory mechanism that controls signal transduction in living cells. The number of identified phosphoproteins and their phosphosites is rapidly increasing as a result of recent mass spectrometry-based approaches.We analyzed time-course phosphoproteome data obtained previously by liquid chromatography mass spectrometry with the stable isotope labeling using amino acids in cell culture (SILAC) method. This provides the relative phosphorylation activities of digested peptides at each of five time points after stimulating HeLa cells with epidermal growth factor (EGF). We initially calculated the correlations between the phosphorylation dynamics patterns of every pair of peptides and connected the strongly correlated pairs to construct a network. We found that peptides extracted from the same intracellular fraction (nucleus vs. cytoplasm) tended to be close together within this phosphorylation dynamics-based network. The network was then analyzed using graph theory and compared with five known signal-transduction pathways. The dynamics-based network was correlated with known signaling pathways in the NetPath and Phospho.ELM databases, and especially with the EGF receptor (EGFR) signaling pathway. Although the phosphorylation patterns of many proteins were drastically changed by the EGF stimulation, our results suggest that only EGFR signaling transduction was both strongly activated and precisely controlled.The construction of a phosphorylation dynamics-based network provides a useful overview of condition-specific intracellular signal transduction using quantitative time-course phosphoproteome data under specific experimental conditions. Detailed prediction of signal transduction based on phosphoproteome dynamics remains challenging. However, since the phosphorylation profiles of kinase-substrate pairs on the specific pathway were localized in the dynamics-based network, our method will be a complementary strategy to explore new components of protein signaling pathways in combination with previous methods (including software) of predicting direct kinase-substrate relationships.","Title: GEMBASSY: an EMBOSS associated software package for comprehensive genome analyses.\nYear: 2013\n\nAbstract: The popular European Molecular Biology Open Software Suite (EMBOSS) currently contains over 400 tools used in various bioinformatics researches, equipped with sophisticated development frameworks for interoperability and tool discoverability as well as rich documentations and various user interfaces. In order to further strengthen EMBOSS in the fields of genomics, we here present a novel EMBOSS associated software (EMBASSY) package named GEMBASSY, which adds more than 50 analysis tools from the G-language Genome Analysis Environment and its Representational State Transfer (REST) and SOAP web services. GEMBASSY basically contains wrapper programs of G-language REST/SOAP web services to provide intuitive and easy access to various annotations within complete genome flatfiles, as well as tools for analyzing nucleic composition, calculating codon usage, and visualizing genomic information. For example, analysis methods such as for calculating distance between sequences by genomic signatures and for predicting gene expression levels from codon usage bias are effective in the interpretation of meta-genomic and meta-transcriptomic data. GEMBASSY tools can be used seamlessly with other EMBOSS tools and UNIX command line tools. The source code written in C is available from GitHub (https://github.com/celery-kotone/GEMBASSY/) and the distribution package is freely available from the GEMBASSY web site (http://www.g-language.org/gembassy/).","Title: The E-CELL project: Towards integrative simulation of cellular processes\nYear: 2000\n\nAbstract: The E-CELL project was launched in 1996 at Keio University in order to model and simulate various cellular processes with the ultimate goal of simulating the cell as a whole. The first version of the E-CELL simulation system, which is a generic software package for cell modeling, was completed in 1997. The E-CELL system enables us to model not only metabolic pathways but also other higher-order cellular processes such as protein synthesis and membrane transport within the same framework. These various processes can then be integrated into a single simulation model. Using the E-CELL system, we have successfully constructed a virtual cell with 127 genes sufficient for \"self-support\". The gene set was selected from the genome of Mycoplasma genitalium, the organism having the smallest known genome. The set includes genes for transcription, translation, the glycolysis pathway for energy production, membrane transport, and the phospholipid biosynthesis pathway for membrane structure. The E-CELL system has been made available for beta testing from our website (http://www.e-cell.org).","Title: The E-CELL project: towards integrative simulation of cellular processes\nYear: 2000\n\nAbstract: The E-CELL project was launched in 1996 at Keio University in order to model and simulate various cellular processes with the ultimate goal of simulating the cell as a whole. The first version of the E-CELL simulation system, which is a generic software package for cell modeling, was completed in 1997. The E-CELL system enables us to model not only metabolic pathways but also other higher-order cellular processes such as protein synthesis and membrane transport within the same framework. These various processes can then be integrated into a single simulation model.Using the E-CELL system, we have successfully constructed a virtual cell with 127 genes sufficient for “self-support”. The gene set was selected from the genome of Mycoplasma genitalium the organism having the smallest known genome. The set includes genes for transcription, translation, the glycolysis pathway for energy production, membrane transport, and the phospholipid biosynthesis pathway for membrane structure.The E-CELL system has been made available for beta testing from our website (http: //www.e-cell.org).","Title: Computational analysis suggests that alternative first exons are involved in tissue-specific transcription in rice (Oryza sativa).\nYear: 2005\n\nAbstract: Transcription start site selection and alternative splicing greatly contribute to diversifying gene expression. Recent studies have revealed the existence of alternative first exons, but most have involved mammalian genes, and as yet the regulation of usage of alternative first exons has not been clarified, especially in plants.We systematically identified putative alternative first exon transcripts in rice, verified the candidates using RT-PCR, and searched for the promoter elements that might regulate the alternative first exons. As a result, we detected a number of unreported alternative first exons, some of which are regulated in a tissue-specific manner.http://www.bioinfo.sfc.keio.ac.jp/research/intron.","Title: Comparison of metabolite production capability indices generated by network analysis methods.\nYear: 2008\n\nAbstract: A framework of constraint-based reconstruction and analysis (COBRA) is used for modeling large-scale metabolic networks. In COBRA, extreme pathway and optimization analyses are commonly used to study the properties of networks.","Title: Characterization of the splice sites in GT-AG and GC-AG introns in higher eukaryotes using full-length cDNAs.\nYear: 2004\n\nAbstract: For the purpose of analyzing the relation between the splice sites and the order of introns, we conducted the following analysis for the GT-AG and GC-AG splice site groups. First, the pre-mRNAs of H. sapiens, M. musculus, D. melanogaster, A. thaliana and O. sativa were sampled by mapping the full-length cDNA to the genomes. Next, the consensus sequences at different regions of pre-mRNAs were analyzed in the five species. We also investigated the mononucleotide and dinucleotide frequencies in the extensive regions around the 5' splice sites (5'ss) and 3' splice sites (3'ss). As a result, differential frequencies of nucleotides at the first 5'ss in both the GT-AG and GC-AG splice site groups were observed in A. thaliana and O. sativa pre-mRNAs. The trend, which indicates that GC 5'ss possess strong consensus sequences, was observed not only in mammalian pre-mRNAs but also in the pre-mRNAs of D. melanogaster, A. thaliana and O. sativa. Furthermore, we examined the consensus sequences of the constitutive and alternative splice sites. It was suggested that in the case of the alternative GC-AG introns, the tendency to have a weak consensus sequence at 5'ss is different between H. sapiens and M. musculus pre-mRNAs.","Title: Time-resolved metabolomics reveals metabolic modulation in rice foliage.\nYear: 2008\n\nAbstract: To elucidate the interaction of dynamics among modules that constitute biological systems, comprehensive datasets obtained from \"omics\" technologies have been used. In recent plant metabolomics approaches, the reconstruction of metabolic correlation networks has been attempted using statistical techniques. However, the results were unsatisfactory and effective data-mining techniques that apply appropriate comprehensive datasets are needed.Using capillary electrophoresis mass spectrometry (CE-MS) and capillary electrophoresis diode-array detection (CE-DAD), we analyzed the dynamic changes in the level of 56 basic metabolites in plant foliage (Oryza sativa L. ssp. japonica) at hourly intervals over a 24-hr period. Unsupervised clustering of comprehensive metabolic profiles using Kohonen's self-organizing map (SOM) allowed classification of the biochemical pathways activated by the light and dark cycle. The carbon and nitrogen (C/N) metabolism in both periods was also visualized as a phenotypic linkage map that connects network modules on the basis of traditional metabolic pathways rather than pairwise correlations among metabolites. The regulatory networks of C/N assimilation/dissimilation at each time point were consistent with previous works on plant metabolism. In response to environmental stress, glutathione and spermidine fluctuated synchronously with their regulatory targets. Adenine nucleosides and nicotinamide coenzymes were regulated by phosphorylation and dephosphorylation. We also demonstrated that SOM analysis was applicable to the estimation of unidentifiable metabolites in metabolome analysis. Hierarchical clustering of a correlation coefficient matrix could help identify the bottleneck enzymes that regulate metabolic networks.Our results showed that our SOM analysis with appropriate metabolic time-courses effectively revealed the synchronous dynamics among metabolic modules and elucidated the underlying biochemical functions. The application of discrimination of unidentified metabolites and the identification of bottleneck enzymatic steps even to non-targeted comprehensive analysis promise to facilitate an understanding of large-scale interactions among components in biological systems.","Title: Can complex cellular processes be governed by simple linear rules?\nYear: 2009\n\nAbstract: Complex living systems have shown remarkably well-orchestrated, self-organized, robust, and stable behavior under a wide range of perturbations. However, despite the recent generation of high-throughput experimental datasets, basic cellular processes such as division, differentiation, and apoptosis still remain elusive. One of the key reasons is the lack of understanding of the governing principles of complex living systems. Here, we have reviewed the success of perturbation-response approaches, where without the requirement of detailed in vivo physiological parameters, the analysis of temporal concentration or activation response unravels biological network features such as causal relationships of reactant species, regulatory motifs, etc. Our review shows that simple linear rules govern the response behavior of biological networks in an ensemble of cells. It is daunting to know why such simplicity could hold in a complex heterogeneous environment. Provided physical reasons can be explained for these phenomena, major advancement in the understanding of basic cellular processes could be achieved.","Title: G-language genome analysis environment with REST and SOAP web service interfaces.\nYear: 2010\n\nAbstract: G-language genome analysis environment (G-language GAE) contains more than 100 programs that focus on the analysis of bacterial genomes, including programs for the identification of binding sites by means of information theory, analysis of nucleotide composition bias and the distribution of particular oligonucleotides, calculation of codon bias and prediction of expression levels, and visualization of genomic information. We have provided a collection of web services for these programs by utilizing REST and SOAP technologies. The REST interface, available at http://rest.glanguage.org/, provides access to all 145 functions of the G-language GAE. These functions can be accessed from other online resources. All analysis functions are represented by unique universal resource identifiers. Users can access the functions directly via the corresponding universe resource locators (URLs), and biological web sites can readily embed the functions by simply linking to these URLs. The SOAP services, available at http://www.g-language.org/wiki/soap/, provide language-independent programmatic access to 77 analysis programs. The SOAP service Web Services Definition Language file can be readily loaded into graphical clients such as the Taverna workbench to integrate the programs with other services and workflows.","Title: Mmmdb: Mouse Multiple Tissue Metabolome Database\nYear: 2012\n\nAbstract: The Mouse Multiple Tissue Metabolome Database (MMMDB) provides comprehensive and quantitative metabolomic information for multiple tissues from single mice. Manually curated databases that integrate literature-based individual metabolite information have been available so far. However, data sets on the absolute concentration of a single metabolite integrated from multiple resources are often difficult to be used when different metabolomic studies are compared because the relative balance of the multiple metabolite concentrations in the metabolic pathways as a snapshot of a dynamic system is more important than the absolute concentration of a single metabolite. We developed MMMDB by performing non-targeted analyses of cerebra, cerebella, thymus, spleen, lung, liver, kidney, heart, pancreas, testis and plasma using capillary electrophoresis time-of-flight mass spectrometry and detected 428 non-redundant features from which 219 metabolites were successfully identified. Quantified concentrations of the individual metabolites and the corresponding processed raw data; for example, the electropherograms and mass spectra with their annotations, such as isotope and fragment information, are stored in the database. MMMDB is designed to normalize users' data, which can be submitted online and used to visualize overlaid electropherograms. Thus, MMMDB allows newly measured data to be compared with the other data in the database. MMMDB is available at: http://mmmdb.iab.keio.ac.jp.","Title: Aligning LC peaks by converting gradient retention times to retention index of peptides in proteomic experiments.\nYear: 2008\n\nAbstract: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful tool in proteomics studies, but when peptide retention information is used for identification purposes, it remains challenging to compare multiple LC-MS/MS runs or to match observed and predicted retention times, because small changes of LC conditions unavoidably lead to variability in retention times. In addition, non-contiguous retention data obtained with different LC-MS instruments or in different laboratories must be aligned to confirm and utilize rapidly accumulating published proteomics data.We have developed a new alignment method for peptide retention times based on linear solvent strength (LSS) theory. We found that log k(0) (logarithm of retention factor for a given organic solvent) in the LSS theory can be utilized as a 'universal' retention index of peptides (RIP) that is independent of LC gradients, and depends solely on the constituents of the mobile phase and the stationary phases. We introduced a machine learning-based scheme to optimize the conversion function of gradient retention times (t(g)) to log k(0). Using the optimized function, t(g) values obtained with different LC-MS systems can be directly compared with each other on the RIP scale. In an examination of Arabidopsis proteomic data, the vast majority of retention time variability was removed, and five datasets obtained with various LC-MS systems were successfully aligned on the RIP scale.","Title: Integrative Features Of The Yeast Phosphoproteome And Protein-Protein Interaction Map\nYear: 2011\n\nAbstract: Following recent advances in high-throughput mass spectrometry (MS)-based proteomics, the numbers of identified phosphoproteins and their phosphosites have greatly increased in a wide variety of organisms. Although a critical role of phosphorylation is control of protein signaling, our understanding of the phosphoproteome remains limited. Here, we report unexpected, large-scale connections revealed between the phosphoproteome and protein interactome by integrative data-mining of yeast multi-omics data. First, new phosphoproteome data on yeast cells were obtained by MS-based proteomics and unified with publicly available yeast phosphoproteome data. This revealed that nearly 60% of similar to 6,000 yeast genes encode phosphoproteins. We mapped these unified phosphoproteome data on a yeast protein-protein interaction (PPI) network with other yeast multi-omics datasets containing information about proteome abundance, proteome disorders, literature-derived signaling reactomes, and in vitro substratomes of kinases. In the phospho-PPI, phosphoproteins had more interacting partners than nonphosphoproteins, implying that a large fraction of intracellular protein interaction patterns (including those of protein complex formation) is affected by reversible and alternative phosphorylation reactions. Although highly abundant or unstructured proteins have a high chance of both interacting with other proteins and being phosphorylated within cells, the difference between the number counts of interacting partners of phosphoproteins and nonphosphoproteins was significant independently of protein abundance and disorder level. Moreover, analysis of the phospho-PPI and yeast signaling reactome data suggested that co-phosphorylation of interacting proteins by single kinases is common within cells. These multi-omics analyses illuminate how wide-ranging intracellular phosphorylation events and the diversity of physical protein interactions are largely affected by each other.","Title: Multiresolution analysis uncovers hidden conservation of properties in structurally and functionally similar proteins.\nYear: 2006\n\nAbstract: Physicochemcial properties of amino acids are important factors in determining protein structure and function. Most approaches make use of averaged properties over entire domains or even proteins to analyze their structure or function. This level of coarseness tends to hide the richness of the variability in the different properties across functional domains. This paper studies the conservation of physicochemical properties in a functionally similar family of proteins using a novel wavelet-based technique known as multiresolution analysis. Such an analysis can help uncover characteristics that can otherwise remain hidden. We have studied the protein kinase family of sequences and our findings are as follows: (a) a number of different properties are conserved over the functional catalytic domain irrespective of the sequence identities; (b) conservation of properties can be observed at different frequency levels and they agree well with the known structural/functional properties of the subdomains for the protein kinase family; (c) structural differences between the different kinase family members are reflected in the waveforms; and (d) functionally important mutations show distortions in the waveforms of conserved properties. The potential usefulness of the above findings in identifying functionally similar sequences in the twilight and midnight zones is demonstrated through a simple prediction model for the protein kinase family which achieved a recall of 93.7% and a precision of 96.75% in cross-validation tests.","Title: Inferring rules of Escherichia coli translational efficiency using an artificial neural network.\nYear: 2007\n\nAbstract: Although the machinery for translation initiation in Escherichia coli is very complicated, the translational efficiency has been reported to be predictable from upstream oligonucleotide sequences. Conventional models have difficulties in their generalization ability and prediction nonlinearity and in their ability to deal with a variety of input attributions. To address these issues, we employed structural learning by artificial neural networks to infer general rules for translational efficiency. The correlation between translational activities measured by biological experiments and those predicted by our method in the test data was significant (r=0.78), and our method uncovered underlying rules of translational activities and sequence patterns from the obtained skeleton structure. The significant rules for predicting translational efficiency were (1) G- and A-rich oligonucleotide sequences, resembling the Shine–Dalgarno sequence, at positions −10 to −7; (2) first base A in the initiation codon; (3) transport/binding or amino acid metabolism gene function; (4) high binding energy between mRNA and 16S rRNA at positions −15 to −5. An additional inferred novel rule was that C at position −1 increases translational efficiency. When our model was applied to the entire genomic sequence of E. coli, translational activities of genes for metabolism and translational were significantly high.","Title: emPAI Calc--for the estimation of protein abundance from large-scale identification data by liquid chromatography-tandem mass spectrometry.\nYear: 2010\n\nAbstract: AemPAI Calc is an open-source web application for the estimation of protein abundance. It uses the correlation between the number of identified peptides and protein abundance in mass spectrometry-based proteomic experiments. The program is the first implementation of our previously reported emPAI algorithm; it calculates the emPAI from the protein identification results obtained by database search engines such as Mascot.(TM)","Title: Restauro-G: a rapid genome re-annotation system for comparative genomics.\nYear: 2007\n\nAbstract: Annotations of complete genome sequences submitted directly from sequencing projects are diverse in terms of annotation strategies and update frequencies. These inconsistencies make comparative studies difficult. To allow rapid data preparation of a large number of complete genomes, automation and speed are important for genome re-annotation. Here we introduce an open-source rapid genome re-annotation software system, Restauro-G, specialized for bacterial genomes. Restauro-G re-annotates a genome by similarity searches utilizing the BLAST-Like Alignment Tool, referring to protein databases such as UniProt KB, NCBI nr, NCBI COGs, Pfam, and PSORTb. Re-annotation by Restauro-G achieved over 98% accuracy for most bacterial chromosomes in comparison with the original manually curated annotation of EMBL releases. Restauro-G was developed in the generic bioinformatics workbench G-language Genome Analysis Environment and is distributed at http://restauro-g.iab.keio.ac.jp/under the GNU General Public License.","Title: KBWS: an EMBOSS associated package for accessing bioinformatics web services.\nYear: 2011\n\nAbstract: The availability of bioinformatics web-based services is rapidly proliferating, for their interoperability and ease of use. The next challenge is in the integration of these services in the form of workflows, and several projects are already underway, standardizing the syntax, semantics, and user interfaces. In order to deploy the advantages of web services with locally installed tools, here we describe a collection of proxy client tools for 42 major bioinformatics web services in the form of European Molecular Biology Open Software Suite (EMBOSS) UNIX command-line tools. EMBOSS provides sophisticated means for discoverability and interoperability for hundreds of tools, and our package, named the Keio Bioinformatics Web Service (KBWS), adds functionalities of local and multiple alignment of sequences, phylogenetic analyses, and prediction of cellular localization of proteins and RNA secondary structures. This software implemented in C is available under GPL from http://www.g-language.org/kbws/ and GitHub repository http://github.com/cory-ko/KBWS. Users can utilize the SOAP services implemented in Perl directly via WSDL file at http://soap.g-language.org/kbws.wsdl (RPC Encoded) and http://soap.g-language.org/kbws_dl.wsdl (Document/literal).","Title: Protein complex prediction via verifying and reconstructing the topology of domain-domain interactions.\nYear: 2010\n\nAbstract: High-throughput methods for detecting protein-protein interactions enable us to obtain large interaction networks, and also allow us to computationally identify the associations of proteins as protein complexes. Although there are methods to extract protein complexes as sets of proteins from interaction networks, the extracted complexes may include false positives because they do not account for the structural limitations of the proteins and thus do not check that the proteins in the extracted complex can simultaneously bind to each other. In addition, there have been few searches for deeper insights into the protein complexes, such as of the topology of the protein-protein interactions or into the domain-domain interactions that mediate the protein interactions.Here, we introduce a combinatorial approach for prediction of protein complexes focusing not only on determining member proteins in complexes but also on the DDI/PPI organization of the complexes. Our method analyzes complex candidates predicted by the existing methods. It searches for optimal combinations of domain-domain interactions in the candidates based on an assumption that the proteins in a candidate can form a true protein complex if each of the domains is used by a single protein interaction. This optimization problem was mathematically formulated and solved using binary integer linear programming. By using publicly available sets of yeast protein-protein interactions and domain-domain interactions, we succeeded in extracting protein complex candidates with an accuracy that is twice the average accuracy of the existing methods, MCL, MCODE, or clustering coefficient. Although the configuring parameters for each algorithm resulted in slightly improved precisions, our method always showed better precision for most values of the parameters.Our combinatorial approach can provide better accuracy for prediction of protein complexes and also enables to identify both direct PPIs and DDIs that mediate them in complexes.","Title: LR parsers for natural languages\nYear: 1984\n\nAbstract: MLR, an extended LR parser, is introduced, and its application to natural language parsing is discussed. An LR parser is a shift-reduce parser which is deterministically guided by a parsing table. A parsing table can be obtained automatically from a context-free phrase structure grammar. LR parsers cannot manage ambiguous grammars such as natural language grammars, because their parsing tables would have multiply-defined entries, which precludes deterministic parsing. MLR, however, can handle multiply-defined entries, using a dynamic programming method. When an input sentence is ambiguous, the MLR parser produces all possible parse trees without parsing any part of the input sentence more than once in the same way, despite the fact that the parser does not maintain a chart as in chart parsing. Our method also provides an elegant solution to the problem of multi-part-of-speech words such as \"that\". The MLR parser and its parsing table generator have been implemented at Carnegie-Mellon University.","Title: Graph-structured Stack and natural language parsing\nYear: 1988\n\nAbstract: A general device for handling nondeterminism in stack operations is described. The device, called a Graph-structured Stack, can eliminate duplication of operations throughout the nondeterministic processes. This paper then applies the graph-structured stack to various natural language parsing methods, including ATN, LR parsing, categorial grammar and principle-based parsing. The relationship between the graph-structured stack and a chart in chart parsing is also discussed.","Title: A microarray data-based semi-kinetic method for predicting quantitative dynamics of genetic networks.\nYear: 2005\n\nAbstract: BACKGROUND: Elucidating the dynamic behaviour of genetic regulatory networks is one of the most significant challenges in systems biology. However, conventional quantitative predictions have been limited to small networks because publicly available transcriptome data has not been extensively applied to dynamic simulation. RESULTS: We present a microarray data-based semi-kinetic (MASK) method which facilitates the prediction of regulatory dynamics of genetic networks composed of recurrently appearing network motifs with reasonable accuracy. The MASK method allows the determination of model parameters representing the contribution of regulators to transcription rate from time-series microarray data. Using a virtual regulatory network and a Saccharomyces cerevisiae ribosomal protein gene module, we confirmed that a MASK model can predict expression profiles for various conditions as accurately as a conventional kinetic model. CONCLUSION: We have demonstrated the MASK method for the construction of dynamic simulation models of genetic networks from time-series microarray data, initial mRNA copy number and first-order degradation constants of mRNA. The quantitative accuracy of the MASK models has been confirmed, and the results indicated that this method enables the prediction of quantitative dynamics in genetic networks composed of commonly used network motifs, which cover considerable fraction of the whole network.","Title: SPLITS: A New Program for Predicting Split and Intron-Containing tRNA Genes at the Genome Level.\nYear: 2006\n\nAbstract: In the archaea, some tRNA precursors contain intron(s) not only in the anticodon loop region but also in diverse sites of the gene (intron-containing tRNA or cis-spliced tRNA). The parasite Nanoarchaeum equitans, a member of the Nanoarchaeota kingdom, creates functional tRNA from separate genes, one encoding the 5'-half and the other the 3'-half (split tRNA or trans-spliced tRNA). Although recent genome projects have revealed a huge amount of nucleotide sequence data in the archaea, a comprehensive methodology for intron-containing and split tRNA searching is yet to be established. We therefore developed SPLITS, which is aimed at searching for any type of tRNA gene and is especially focused on intron-containing tRNAs or split tRNAs at the genome level. SPLITS initially predicts the bulge-helix-bulge splicing motif (a well-known, required structure in archaeal pre-tRNA introns) to determine and remove the intronic regions of tRNA genes. The intron-removed DNA sequences are automatically queried to tRNAscan-SE. SPLITS can predict known tRNAs with single introns located at unconventional sites on the genes (100%), tRNAs with double introns (85.7%), and known split tRNAs (100%). Our program will be very useful for identifying novel tRNA genes after completion of genome projects. The SPLITS source code is freely downloadable at http://splits.iab.keio.ac.jp/.","Title: Robust effects of Tsr-CheBp and CheA-CheYp affinity in bacterial chemotaxis.\nYear: 2007\n\nAbstract: Cell motility and chemotaxis play a role in the virulence of pathogenic bacteria, such as escape from host immune responses. Escherichia coli chemotaxis provides a well-characterized model system for the bacterial chemotaxis network. Two features of E. coli chemotaxis include signal amplification and robustly accurate adaptation. Recent simulation studies with models considering the effects of other receptors have suggested possible mechanisms for signal amplification. Although precise adaptation to aspartate has been explained by conventional kinetic models, the adaptation behavior of models incorporating the effects of other receptors remains unclear.We concentrated on how receptor crosstalk affects minimization of adaptation error and compared models in which the contribution of other receptors varied.We demonstrated that the model is adaptable to attractant concentrations ranging from 0.1microM to 10mM with a decreased error rate (from 8% to 2%) when the kinetic constant of CheA and phosphorylated CheY dissociation is increased.The results suggest that accurate adaptation is maintained through control of both the interaction of cytoplasmic Che proteins and the activity of the receptor complex.","Title: Measure of synonymous codon usage diversity among genes in bacteria.\nYear: 2009\n\nAbstract: In many bacteria, intragenomic diversity in synonymous codon usage among genes has been reported. However, no quantitative attempt has been made to compare the diversity levels among different genomes. Here, we introduce a mean dissimilarity-based index (Dmean) for quantifying the level of diversity in synonymous codon usage among all genes within a genome.The application of Dmean to 268 bacterial genomes shows that in bacteria with extremely biased genomic G+C compositions there is little diversity in synonymous codon usage among genes. Furthermore, our findings contradict previous reports. For example, a low level of diversity in codon usage among genes has been reported for Helicobacter pylori, but based on Dmean, the diversity level of this species is higher than those of more than half of bacteria tested here. The discrepancies between our findings and previous reports are probably due to differences in the methods used for measuring codon usage diversity.We recommend that Dmean be used to measure the diversity level of codon usage among genes. This measure can be applied to other compositional features such as amino acid usage and dinucleotide relative abundance as a genomic signature.","Title: Computational analysis of stop codon readthrough in D.melanogaster.\nYear: 2003\n\nAbstract: Motivation: Readthrough is an unusual process in which a stop codon is misread or skipped. Recently it has been shown that some translation is regulated by the readthrough reactions although the complete mechanism is not clear. Therefore, the discovery of 'readthrough genes' is important for further investigation of their cellular roles, which may provide additional insights into the mechanism of translational regulation. Results: We constructed a system that lists candidates of readthrough genes based on the existence of a 'protein motif' at the 3' untranslated region (UTR). Using this system, we extracted 85 candidates from 4082 nucleic acid sequences of Drosophila melanogaster in GenBank database. The sequences of these candidates had a slightly more stable secondary structure and different base preferences compared to the non-candidates. As these features are known to have an effect on readthrough events, we would like to suggest that these candidates contain actual readthrough genes.","Title: Visualization of three-way comparisons of omics data.\nYear: 2007\n\nAbstract: Density plot visualizations (also referred to as heat maps or color maps) are widely used in different fields including large-scale omics studies in biological sciences. However, the current color-codings limit the visualizations to single datasets or pairwise comparisons.We propose a color-coding approach for the representation of three-way comparisons. The approach is based on the HSB (hue, saturation, brightness) color model. The three compared values are assigned specific hue values from the circular hue range (e.g. red, green, and blue). The hue value representing the three-way comparison is calculated according to the distribution of three compared values. If two of the values are identical and one is different, the resulting hue is set to the characteristic hue of the differing value. If all three compared values are different, the resulting hue is selected from a color gradient running between the hues of the two most distant values (as measured by the absolute value of their difference) according to the relative position of the third value between the two. The saturation of the color representing the three-way comparison reflects the amplitude (or extent) of the numerical difference between the two most distant values according to a scale of interest. The brightness is set to a maximum value by default but can be used to encode additional information about the three-way comparison.We propose a novel color-coding approach for intuitive visualization of three-way comparisons of omics data.","Title: Integrative modeling of gene expression and metabolism with E-CELL System\nYear: 2002\n\nAbstract: A gene-expression model for an E-CELL simulation was constructed, and the simulation was carried out. The model was integrated\n with a metabolism model of the self-sustaining virtual cell model which was constructed based on aMycoplasma genitalium cell. Details of the model structure and the results of the simulation are shown. AnEscherichia coli lac-operon model was also constructed by integrating and abstracting the gene-expression model. Wherever possible, experimental\n parameters were used to construct the model","Title: A general computational model of mitochondrial metabolism in a whole organelle scale.\nYear: 2004\n\nAbstract: A computational tool for mitochondrial systems biology has been developed as a simulation model of E-Cell2, a publicly available simulation system. The general model consists of 58 enzymatic reactions and 117 metabolites, representing the respiratory chain, the TCA cycle, the fatty acid beta-oxidation and the inner-membrane transport system. It is based on previously published enzyme kinetics studies in the literature; we have successfully integrated and packaged them into a single large model. The model can be easily extended and modified so that mitochondrial biologists/physiologists can integrate their own models and evaluate them in the context of the whole organelle metabolism.The mitochondrial model is bundled up with E-Cell2 simulation system, which can be downloaded from http://www.e-cell.org. CD-ROMs are also available and are distributed at major conferences.All the kinetic data are available via http://www.e-cell.org","Title: Another stride towards knowledge-based machine translation\nYear: 1986\n\nAbstract: Building on the well-established premise that reliable machine translation requires a significant degree of text comprehension, this paper presents a recent advance in multi-lingual knowledge-based machine translation (KBMT). Unlike previous approaches, the current method provides for separate syntactic and semantic knowledge sources that are integrated dynamically for parsing and generation. Such a separation enables the system to have syntactic grammars, language specific but domain general, and semantic knowledge bases, domain specific but language general. Subsequently, grammars and domain knowledge are precompiled automatically in any desired combination to produce very efficient and very thorough real-time parsers. A pilot implementation of our KBMT architecture using functional grammars and entity-oriented semantics demonstrates the feasibility of the new approach.1","Title: KEGG-Based Pathway Visualization Tool for Complex Omics Data.\nYear: 2005\n\nAbstract: Pathway-level visualization of omics data provides an essential means for systems biology, to capture the systematic properties of the inner activities of cells. Here we describe a web-based resource consisting of a web-application for the visualization of complex omics data onto KEGG pathways to overview all entities in the context of cellular pathways, and databases created with the software to visualize a series of microarray data. The web-application accepts transcriptome, proteome, metabolome, or the combination of these data as input, and because of this scalability it is advantageous for the visualization of cell simulation results. The web server can be accessed at http://www.g-language.org/data/marray/.","Title: GEM System: automatic prototyping of cell-wide metabolic pathway models from genomes.\nYear: 2006\n\nAbstract: Successful realization of a \"systems biology\" approach to analyzing cells is a grand challenge for our understanding of life. However, current modeling approaches to cell simulation are labor-intensive, manual affairs, and therefore constitute a major bottleneck in the evolution of computational cell biology.We developed the Genome-based Modeling (GEM) System for the purpose of automatically prototyping simulation models of cell-wide metabolic pathways from genome sequences and other public biological information. Models generated by the GEM System include an entire Escherichia coli metabolism model comprising 968 reactions of 1195 metabolites, achieving 100% coverage when compared with the KEGG database, 92.38% with the EcoCyc database, and 95.06% with iJR904 genome-scale model.The GEM System prototypes qualitative models to reduce the labor-intensive tasks required for systems biology research. Models of over 90 bacterial genomes are available at our web site.","Title: The Integration of Unification-Based Syntax/Semantics and Memory-Based Pragmatics for Real-Time Understanding of Noisy Continuous Speech Input\nYear: 1988\n\nAbstract: Real-time understanding of speech input is difficult especially because the input is often noisy and elliptic. Multiple morphophonemic and lexical hypotheses generated for a single input sentence cannot be resolved by local semantics alone. We have developed a system in which unilication-based parsing of speech input is integrated with thematic memory-based spreading activation that supplies extra-sentential knowledge that can help to disambiguate noisy and elliptic real-time speaker-independent continuous speech input.","Title: Variation in the correlation of G + C composition with synonymous codon usage bias among bacteria.\nYear: 2007\n\nAbstract: G + C composition at the third codon position (GC3) is widely reported to be correlated with synonymous codon usage bias. However, no quantitative attempt has been made to compare the extent of this correlation among different genomes. Here, we applied Shannon entropy from information theory to measure the degree of GC3 bias and that of synonymous codon usage bias of each gene. The strength of the correlation of GC3 with synonymous codon usage bias, quantified by a correlation coefficient, varied widely among bacterial genomes, ranging from -0.07 to 0.95. Previous analyses suggesting that the relationship between GC3 and synonymous codon usage bias is independent of species are thus inconsistent with the more detailed analyses obtained here for individual species.","Title: eXpanda: An Integrated Platform for Network Analysis and Visualization.\nYear: 2007\n\nAbstract: Analysis and visualization of biological networks, such as protein-protein and protein-DNA interactions, are crucially important toward obtaining a thorough understanding of living systems. Here, we present an integrative software platform, eXpanda, which enables an analysis of a very broad range of biological networks, with a special focus on the extraction of characteristic topologies which potentially function as units in the networks. eXpanda is provided as a Perl library which gives full-automatic connections to various biological databases via a Perl programmable interface and can perform topological analysis based on graph theory. The results of these analyses are visualizable by vector graphics. eXpanda is under GNU General Public License. Software package, detailed documentations, source codes, and some sample scripts are downloadable at http://medcd.iab.keio.ac.jp/expanda/.","Title: Prediction of axillary lymph node metastasis in primary breast cancer patients using a decision tree-based model.\nYear: 2012\n\nAbstract: The aim of this study was to develop a new data-mining model to predict axillary lymph node (AxLN) metastasis in primary breast cancer. To achieve this, we used a decision tree-based prediction method-the alternating decision tree (ADTree).Clinical datasets for primary breast cancer patients who underwent sentinel lymph node biopsy or AxLN dissection without prior treatment were collected from three institutes (institute A, n = 148; institute B, n = 143; institute C, n = 174) and were used for variable selection, model training and external validation, respectively. The models were evaluated using area under the receiver operating characteristics (ROC) curve analysis to discriminate node-positive patients from node-negative patients.The ADTree model selected 15 of 24 clinicopathological variables in the variable selection dataset. The resulting area under the ROC curve values were 0.770 [95% confidence interval (CI), 0.689-0.850] for the model training dataset and 0.772 (95% CI: 0.689-0.856) for the validation dataset, demonstrating high accuracy and generalization ability of the model. The bootstrap value of the validation dataset was 0.768 (95% CI: 0.763-0.774).Our prediction model showed high accuracy for predicting nodal metastasis in patients with breast cancer using commonly recorded clinical variables. Therefore, our model might help oncologists in the decision-making process for primary breast cancer patients before starting treatment.","Title: Dynamic modeling of genetic networks using genetic algorithm and S-system.\nYear: 2003\n\nAbstract: Motivation: The modeling of system dynamics of genetic networks, metabolic networks or signal transduction cascades from time-course data is formulated as a reverse-problem. Previous studies focused on the estimation of only network structures, and they were ineffective in inferring a network structure with feedback loops. We previously proposed a method to predict not only the network structure but also its dynamics using a Genetic Algorithm (GA) and an S-system formalism. However, it could predict only a small number of parameters and could rarely obtain essential structures. In this work, we propose a unified extension of the basic method. Notable improvements are as follows: (1) an additional term in its evaluation function that aims at eliminating futile parameters; (2) a crossover method called Simplex Crossover (SPX) to improve its optimization ability; and (3) a gradual optimization strategy to increase the number of predictable parameters. Results: The proposed method is implemented as a C program called PEACE1 (Predictor by Evolutionary Algorithms and Canonical Equations 1). Its performance was compared with the basic method. The comparison showed that: (1) the convergence rate increased about 5-fold; (2) the optimization speed was raised about 1.5-fold; and (3) the number of predictable parameters was increased about 5-fold. Moreover, we successfully inferred the dynamics of a small genetic network constructed with 60 parameters for 5 network variables and feedback loops using only time-course data of gene expression.","Title: Comparative study of circadian oscillatory network models of Drosophila.\nYear: 2008\n\nAbstract: The circadian clock of Drosophila is a model pathway for research in biological clock mechanisms, both with traditional experimental approaches and with emerging systems biology approaches utilizing mathematical modeling and in silico computer simulation. Dynamic diurnal oscillations are achieved by the complex interaction of components as a system, and mathematical reconstruction has proven to be an invaluable means of understanding such systematic behavior. In this study, we implemented eight published models of the Drosophila circadian clock in Systems Biology Markup Language (SBML) for comparative systems biology studies using E-Cell Simulation Environment version 3, to examine the system-level requirements for the clock mechanism to be robust, by calculating the period and amplitude sensitivity coefficients with simulation experiments. While all models were generally robust as determined by the network topology of the oscillatory feedback loop structure, existing models place relatively strong emphasis on transcription regulation, although this is a limitation on robustness. We suggest that more comprehensive modeling including protein phosphorylation, polymerization, and nuclear transport with regard to amplitude sensitivity will be necessary for understanding the light entrainment and temperature compensation of circadian clocks.","Title: A multi-algorithm, multi-timescale method for cell simulation.\nYear: 2004\n\nAbstract: Many important problems in cell biology require the dense nonlinear interactions between functional modules to be considered. The importance of computer simulation in understanding cellular processes is now widely accepted, and a variety of simulation algorithms useful for studying certain subsystems have been designed. Many of these are already widely used, and a large number of models constructed on these existing formalisms are available. A significant computational challenge is how we can integrate such sub-cellular models running on different types of algorithms to construct higher order models.A modular, object-oriented simulation meta-algorithm based on a discrete-event scheduler and Hermite polynomial interpolation has been developed and implemented. It is shown that this new method can efficiently handle many components driven by different algorithms and different timescales. The utility of this simulation framework is demonstrated further with a 'composite' heat-shock response model that combines the Gillespie-Gibson stochastic algorithm and deterministic differential equations. Dramatic improvements in performance were obtained without significant accuracy drawbacks. A multi-timescale demonstration of coupled harmonic oscillators is also shown.","Title: The universal parser architecture for knowledge-based machine translation\nYear: 1987\n\nAbstract: Machine translation should be semanticalty-accurate, linguistically-principled, user-interactive, and extensible to multiple languages and domains. This paper presents the universal parser architecture that strives to meet these objectives. In essence, linguistic knowledge bases (syntactic, semantic, lexical, pragmatic), encoded in theoretically-motivated formalisms such as lexical-functional grammars, are unified and precompiled into fast run-time grammars for parsing and generation. Thus, the universal parser provides principled run-time integration of syntax and semantics, while preserving the generality of domain-independent syntactic grammars, and language-independent domain knowledge bases; the optimized cross product is generated automatically in the precornpllation phase. Initial results for bi-directional English-Japanese translation show considerable promise both in terms of demonstrating the theoretical feasibillty of the approach and in terms of subsequent practical utility.","Title: Genome Projector: zoomable genome map with multiple views.\nYear: 2009\n\nAbstract: Molecular biology data exist on diverse scales, from the level of molecules to -omics. At the same time, the data at each scale can be categorised into multiple layers, such as the genome, transcriptome, proteome, metabolome, and biochemical pathways. Due to the highly multi-layer and multi-dimensional nature of biological information, software interfaces for database browsing should provide an intuitive interface that allows for rapid migration across different views and scales. The Zoomable User Interface (ZUI) and tabbed browsing have proven successful for this purpose in other areas, especially to navigate the vast information in the World Wide Web.This paper presents Genome Projector, a Web-based gateway for genomics information with a zoomable user interface using Google Maps API, equipped with four seamlessly accessible and searchable views: a circular genome map, a traditional genome map, a biochemical pathways map, and a DNA walk map. The Web application for 320 bacterial genomes is available at http://www.g-language.org/GenomeProjector/. All data and software including the source code, documentations, and development API are freely available under the GNU General Public License. Zoomable maps can be easily created from any image file using the development API, and an online data mapping service for Genome Projector is also available at our Web site.Genome Projector is an intuitive Web application for browsing genomics information, implemented with a zoomable user interface and tabbed browsing utilising Google Maps API and Asynchronous JavaScript and XML (AJAX) technology.","Title: GeNESiS: gene network evolution simulation software.\nYear: 2008\n\nAbstract: Background: There has been a lot of interest in recent years focusing on the modeling and simulation of Gene Regulatory Networks (GRNs). However, the evolutionary mechanisms that give rise to GRNs in the first place are still largely unknown. In an earlier work, we developed a framework to analyze the effect of objective functions, input types and starting populations on the evolution of GRNs with a specific emphasis on the robustness of evolved GRNs. Results: In this work, we present a parallel software package, GeNESiS for the modeling and simulation of the evolution of gene regulatory networks (GRNs). The software models the process of gene regulation through a combination of finite-state and stochastic models. The evolution of GRNs is then simulated by means of a genetic algorithm with the network connections represented as binary strings. The software allows users to simulate the evolution under varying selective pressures and starting conditions. We believe that the software provides a way for researchers to understand the evolutionary behavior of populations of GRNs. Conclusion: We believe that GeNESiS will serve as a useful tool for scientists interested in understanding the evolution of gene regulatory networks under a range of different conditions and selective pressures. Such modeling efforts can lead to a greater understanding of the network characteristics of GRNs.","Title: Consideration On Contact Mechanism Of Ybacuo Bulk Superconductor With Deposited Metal Layer\nYear: 2007\n\nAbstract: A persistent current switch (PCS) is used for superconducting applications, such as superconducting magnetic energy storage (SMES) system. The authors have proposed a mechanical switch of Y-Ba-Cu-0 (YBCO) bulk as a mechanical PCS. In previous study, the authors have successfully reduced a residual resistance by depositing with metal on contact surface. This paper focused on a current carrying area (called a-spot) on contact surface and presented an effect of deposited metal on electrical contact characteristics in order to clear the contact mechanism. As the results of experiments and simulation using FEM, it became clear that it was effective for reducing the residual resistance from a view point of increasing the a-spot by depositing with metal.","Title: An efficient augmented-context-free parsing algorithm\nYear: 1987\n\nAbstract: An efficient parsing algorithm for augmented context-free grammars is introduced, and its application to on-line natural language interfaces discussed. The algorithm is a generalized LR parsing algorithm, which precomputes an LR shift-reduce parsing table (possibly with multiple entries) from a given augmented context-free grammar. Unlike the standard LR parsing algorithm, it can handle arbitrary context-free grammars, including ambiguous grammars, while most of the LR efficiency is preserved by introducing the concept of a \"graph-structured stack\". The graph-structured stack allows an LR shift-reduce parser to maintain multiple parses without parsing any part of the input twice in the same way. We can also view our parsing algorithm as an extended chart parsing algorithm efficiently guided by LR parsing tables. The algorithm is fast, due to the LR table precomputation. In several experiments with different English grammars and sentences, timings indicate a five- to tenfold speed advantage over Earley's context-free parsing algorithm.The algorithm parses a sentence strictly from left to right on-line, that is, it starts parsing as soon as the user types in the first word of a sentence, without waiting for completion of the sentence. A practical on-line parser based on the algorithm has been implemented in Common Lisp, and running on Symbolics and HP AI workstations. The parser is used in the multi-lingual machine translation project at CMU. Also, a commercial on-line parser for Japanese language is being built by Intelligent Technology Incorporation, based on the technique developed at CMU.","Title: MEGU: Pathway Mapping Web-Service Based on KEGG and SVG.\nYear: 2006\n\nAbstract: Scientific visualization is a key technology to enhance our understanding of huge masses of omics data, especially for cell-wide, high-throughput measurements of the physiological networks. We have developed a web application that visualizes complex omics data of multiple layers simultaneously, including transcriptome, proteome, and metabolome, onto an integrated pathway diagram derived by connecting the individual KEGG pathway maps; the mapped images are generated in Scalable Vector Graphics for easy editing by hand or with computer programs or drawing software. The web application is available at http://megu.iab.keio.ac.jp/.","Title: Construction of a biological tissue model based on a single-cell model: a computer simulation of metabolic heterogeneity in the liver lobule.\nYear: 2008\n\nAbstract: An enormous body of information has been obtained by molecular and cellular biology in the last half century. However, even these powerful approaches are not adequate when it comes to higher-level biological structures, such as tissues, organs, and individual organisms, because of the complexities involved. Thus, accumulation of data at the higher levels supports and broadens the context for that obtained on the molecular and cellular levels. Under such auspices, an attempt to elucidate mesoscopic and macroscopic subjects based on plentiful nanoscopic and microscopic data is of great potential value. On the other hand, fully realistic simulation is impracticable because of the extensive cost entailed and enormous amount of data required. Abstraction and modeling that balance the dual requirements of prediction accuracy and manageable calculation cost are of great importance for systems biology. We have constructed an ammonia metabolism model of the hepatic lobule, a histological component of the liver, based on a single-hepatocyte model that consists of the biochemical kinetics of enzymes and transporters. To bring the calculation cost within reason, the porto-central axis, which is an elemental structure of the lobule, is defined as the systems biological unit of the liver, and is accordingly modeled. A model including both histological structure and position-specific gene expression of major enzymes largely represents the physiological dynamics of the hepatic lobule in nature. In addition, heterogeneous gene expression is suggested to have evolved to optimize the energy efficiency of ammonia detoxification at the macroscopic level, implying that approaches like this may elucidate how properties at the molecular and cellular levels, such as regulated gene expression, modify higher-level phenomena of multicellular tissue, organs, and organisms.","Title: A web server for interactive and zoomable Chaos Game Representation images.\nYear: 2009\n\nAbstract: Chaos Game Representation (CGR) is a generalized scale-independent Markov transition table, which is useful for the visualization and comparative study of genomic signature, or for the study of characteristic sequence motifs. However, in order to fully utilize the scale-independent properties of CGR, it should be accessible through scale-independent user interface instead of static images. Here we describe a web server and Perl library for generating zoomable CGR images utilizing Google Maps API, which is also easily searchable for specific motifs. The web server is freely accessible at http://www.g-language.org/wiki/cgr/, and the Perl library as well as the source code is distributed with the G-language Genome Analysis Environment under GNU General Public License.","Title: Computational Challenges in Cell Simulation: A Software Engineering Approach\nYear: 2002\n\nAbstract: The simulation of cellular processes involves diverse components and complexinteractions.To successfully model such processes, simulation systems must meet a numberofcomputational requirements, including an object-oriented design.","Title: GPAC: Benchmarking the Sensitivity of Genome Informatics Analysis to Genome Annotation Completeness.\nYear: 2006\n\nAbstract: In view of the recent explosion in genome sequence data, and the 200 or more complete genome sequences currently available, the importance of genome-scale bioinformatics analysis is increasing rapidly. However, computational genome informatics analyses often lack a statistical assessment of their sensitivity to the completeness of the functional annotation. Therefore, a pre-analysis method to automatically validate the sensitivity of computational genome analyses with regard to genome annotation completeness is useful for this purpose. In this report we developed the Gene Prediction Accuracy Classification (GPAC) test, which provides statistical evidence of sensitivity by repeating the same analysis for five different gene groups (classified according to annotation accuracy level), and for randomly sampled gene groups, with the same number of genes as each of the five classified groups. Variability in these results is then assessed, and if the results vary significantly with different data subsets, the analysis is considered \"sensitive\" to annotation completeness, and careful selection of data is advised prior to the actual in silico analysis. The GPAC test has been applied to the analyses of Sakai et al., 2001, and Ohno et al., 2001, and it revealed that the analysis of Ohno et al. was more sensitive to annotation completeness. It showed that GPAC could be employed to ascertain the sensitivity of an analysis. The GPAC bendhmarking software is freely available in the latest G-language Genome Analysis Environment package, at http://www.g-language.org/.","Title: Janus 93: Towards Spontaneous Speech Translation\nYear: 1994\n\nAbstract: Abstract: We present first results from our efforts toward translationof spontaneously spoken speech. Improvements includeincreasing coverage, robustness, generality and speedof JANUS, the speech-to-speech translation system ofCarnegie Mellon and Karlsruhe University. Recognitionand Machine Translation Engine have been upgraded todeal with requirements introduced by spontaneous humanto human dialogs. To allow for development and evaluationof our system on adequate data, a large database with...","Title: A generalized parser for 2-D languages\nYear: 1991\n\nAbstract: The authors present an extension of the Earley's (1970) generalized parser to the case of two-dimensional languages. They describe two-dimensional (positional) grammars as generalizations of context-free string grammars. The technique used to extend the Earley's algorithm is the same used for constructing a positional LR (pLR) parser. The main idea is to allow the parser to choose the next symbol to parse from a two-dimensional space","Title: Future directions for cyber knowledge and databases\nYear: 2004\n\nAbstract: In the design of multimedia database systems, one of the important issues is how to deal with \"Kansei\" of human beings. The concept of \"Kansei\" includes several meanings on sensitive recognition, such as \"human senses,\" \"feelings,\" \"sensitivity,\" \"psychological reaction\" and \"physiological reaction\" [1].In the field of database systems, the concept of Kansei is related to data definition and data retrieval with Kansei information for multimedia data, such as images, music and video. The important subject is to retrieve images and music dynamically according to the user's impression given as Kansei information. We review some multimedia systems which manipulate Kansei information for defining and retrieving multimedia data.","Title: The Dynamics Of Cellular Energetics During Continuous Yeast Culture\nYear: 2013\n\nAbstract: A plethora of data is accumulating from high throughput methods on metabolites, coenzymes, proteins, and nucleic acids and their interactions as well as the signalling and regulatory functions and pathways of the cellular network. The frozen moment viewed in a single discrete time sample requires frequent repetition and updating before any appreciation of the dynamics of component interaction becomes possible. Even then in a sample derived from a cell population, time-averaging of processes and events that occur in out-of-phase individuals blur the detailed complexity of single cell organization. Continuously-grown cultures of yeast can become spontaneously self-synchronized, thereby enabling resolution of far more detailed temporal structure. Continuous on-line monitoring by rapidly responding sensors (O-2 electrode and membrane-inlet mass spectrometry for O-2, CO2 and H2S; direct fluorimetry for NAD(P) H and flavins) gives dynamic information from time-scales of minutes to hours. Supplemented with capillary electophoresis and gas chromatography mass spectrometry and transcriptomics the predominantly oscillatory behaviour of network components becomes evident, with a 40 min cycle between a phase of increased respiration (oxidative phase) and decreased respiration (reductive phase). Highly pervasive, this ultradian clock provides a coordinating function that links mitochondrial energetics and redox balance to transcriptional regulation, mitochondrial structure and organelle remodelling, DNA duplication and cell division events. Ultimately, this leads to a global partitioning of anabolism and catabolism and the enzymes involved, mediated by a relatively simple ATP feedback loop on chromatin architecture.","Title: A Generic Software Platform for Brain-inspired Cognitive Computing.\nYear: 2015\n\nAbstract: We have been developing BriCA (Brain-inspired Computing Architecture), the generic software platform that can combine an arbitrary number of machine learning modules to construct higher structures such as cognitive architectures inspired by the brain. We discuss requirements analysis and design principles of this cognitive computing platform, report its implementation, and describe plans for further development.","Title: BriCA: A Modular Software Platform for Whole Brain Architecture.\nYear: 2016\n\nAbstract: Brain-inspired Computing Architecture (BriCA) is a generic software platform for modular composition of machine learning algorithms. It can combine and schedule an arbitrary number of machine learning components in a brain-inspired fashion to construct higher level structures such as cognitive architectures. We would like to report and discuss the core concepts of BriCA version 1 and prospects toward future development.","Title: MICOP: Maximal information coefficient-based oscillation prediction to detect biological rhythms in proteomics data.\nYear: 2018\n\nAbstract: In this paper, we presented MICOP, which is an MIC-based algorithm, for predicting periodic patterns in large-scale time-resolved protein expression profiles. The performance test using artificially generated simulation data revealed that the performance of MICOP for decaying data was superior to that of the existing widely used methods. It can reveal novel findings from time-series data and may contribute to biologically significant results. This study suggests that MICOP is an ideal approach for detecting and characterizing oscillations in time-resolved omics data sets.","Title: An efficient context-free parsing algorithm for natural languages\nYear: 1985\n\nAbstract: In this paper we present a type inference method for Prolog programs. The new idea is to describe a superset of the success set by associating a type substitution (an assignment of sets of ground terms to variables) with each head of definite clause. ...","Title: Parameter estimation for stiff equations of biosystems using radial basis function networks.\nYear: 2006\n\nAbstract: The modeling of dynamic systems requires estimating kinetic parameters from experimentally measured time-courses. Conventional global optimization methods used for parameter estimation, e.g. genetic algorithms (GA), consume enormous computational time because they require iterative numerical integrations for differential equations. When the target model is stiff, the computational time for reaching a solution increases further.In an attempt to solve this problem, we explored a learning technique that uses radial basis function networks (RBFN) to achieve a parameter estimation for biochemical models. RBFN reduce the number of numerical integrations by replacing derivatives with slopes derived from the distribution of searching points. To introduce a slight search bias, we implemented additional data selection using a GA that searches data-sparse areas at low computational cost. In addition, we adopted logarithmic transformation that smoothes the fitness surface to obtain a solution simply. We conducted numerical experiments to validate our methods and compared the results with those obtained by GA. We found that the calculation time decreased by more than 50% and the convergence rate increased from 60% to 90%.In this work, our RBFN technique was effective for parameter optimization of stiff biochemical models."],"string":"[\n \"Title: Parsing noisy sentences\\nYear: 1988\\n\\nAbstract: This paper describes a method to parse and understand a \\\"noisy\\\" sentence that possibly includes errors caused by a speech recognition device. Our parser is connected to a speech recognition device which takes a continuously spoken sentence in Japanese and produces a sequence of phonemes. The output sequence of phonemes can quite possibly include errors: altered phonemes, extra phonemes and missing phonemes. The task is to parse the noisy phoneme sequence and understand the meaning of the original input sentence, given an augmented context-free grammar whose terminal symbols are phonemes. A very efficient parsing method is required, as the task's search space is much larger than that of parsing un-noisy sentences. We adopt the generalized LR parsing algorithm, and a certain scoring scheme to select the most likely sentence out of multiple sentence candidates. The use of a , which is created in advance by analyzing a large set of input/output pairs, is discussed to improve the scoring accuracy. The system has been integrated into CMU's knowledge-based machine translation system.\",\n \"Title: MathDAMP: a package for differential analysis of metabolite profiles.\\nYear: 2006\\n\\nAbstract: With the advent of metabolomics as a powerful tool for both functional and biomarker discovery, the identification of specific differences between complex metabolite profiles is becoming a major challenge in the data analysis pipeline. The task remains difficult, given the datasets' size, complexity, and common shifts in migration (elution/retention) times between samples analyzed by hyphenated mass spectrometry methods.We present a Mathematica (Wolfram Research, Inc.) package MathDAMP (Mathematica package for Differential Analysis of Metabolite Profiles), which highlights differences between raw datasets acquired by hyphenated mass spectrometry methods by applying arithmetic operations to all corresponding signal intensities on a datapoint-by-datapoint basis. Peak identification and integration is thus bypassed and the results are displayed graphically. To facilitate direct comparisons, the raw datasets are automatically preprocessed and normalized in terms of both migration times and signal intensities. A combination of dynamic programming and global optimization is used for the alignment of the datasets along the migration time dimension. The processed datasets and the results of direct comparisons between them are visualized using density plots (axes represent migration time and m/z values while peaks appear as color-coded spots) providing an intuitive overall view. Various forms of comparisons and statistical tests can be applied to highlight subtle differences. Overlaid electropherograms (chromatograms) corresponding to the vicinities of the candidate differences from any result may be generated in a descending order of significance for visual confirmation. Additionally, a standard library table (a list of m/z values and migration times for known compounds) may be aligned and overlaid on the plots to allow easier identification of metabolites.Our tool facilitates the visualization and identification of differences between complex metabolite profiles according to various criteria in an automated fashion and is useful for data-driven discovery of biomarkers and functional genomics.\",\n \"Title: Parsing spoken language: a semantic caseframe approach\\nYear: 1986\\n\\nAbstract: Parsing spoken input introduces serious problems not present in parsing typed natural language. In particular, indeterminacies and inaccuracies of acoustic recognition must be handled in an integral manner. Many techniques for parsing typed natural language do not adapt well to these extra demands. This paper describes an extension of semantic caseframe parsing to restricted-domain spoken input. The semantic caseframe grammar representation is the same as that used for earlier work on robust parsing of typed input. Due to the uncertainty inherent in speech recognition, the caseframe grammar is applied in a quite different way, emphasizing island growing from caseframe headers. This radical change in application is possible due to the high degree of abstraction in the caseframe representation. The approach presented was tested successfully in a preliminary implementation.\",\n \"Title: Kinetic simulation of signal transduction system in hippocampal long-term potentiation with dynamic modeling of protein phosphatase 2A.\\nYear: 2003\\n\\nAbstract: We modeled and analyzed a signal transduction system of long-term potentiation (LTP) in hippocampal post-synapse. Bhalla and Iyengar [Science 283(1999) 381] have developed a hippocampal LTP model. In the conventional model, the concentration of protein phosphatase 2A (PP2A) was fixed. However, it was reported that dynamic inactivation of PP2A was essential for LTP [J. Neurochem. 74 (2000) 807]. We introduced a dynamic modeling of PP2A; inactivation (phosphorylation) of PP2A by calcium/calmodulin-dependent protein kinase II (CaMKII) in the presence of calcium/calmodulin, self-activation (autodephosphorylation) of PP2A, and inactivation (dephosphorylation) of CaMKII by PP2A. This model includes complex feedback loops; both CaMKII and PP2A are autoactivated, while they inactivate each other. Moreover, we proposed an analysis strategy for model validation by applying the results of sensitivity analysis. In our system, calcineurin (CaN) played an essential role, rather than the activation of protein kinase C (PKC) as documented in the conventional model. From results of the analysis of our model, we found the following robustness as characteristics of bistability in our model: (1). PP2A reactions against calcium ion (Ca(2+)) perturbation; (2). PP2A inactivation against PP2A increase; (3). protein phosphatase 1 (PP1) activation against PF2A increase; and (4). PP2A reactions against PP2A initial concentration. These properties facilitated LTP induction in our system. We showed that another mechanism could introduce bistable behavior by adding dynamic reactions of PP2A.\",\n \"Title: Distributed cell biology simulations with e-cell system\\nYear: 2004\\n\\nAbstract: Many useful applications of simulation in computational cell biology, e.g. kinetic parameter estimation, Metabolic Control Analysis (MCA), and bifurcation analysis, require a large number of repetitive runs with different input parameters. The heavy requirements imposed by these analysis methods on computational resources has led to an increased interest in parallel- and distributed computing technologies. We have developed a scripting environment that can execute, and where possible, automatically parallelize those mathematical analysis sessions transparently on any of (1) single-processor workstations, (2) Shared-memory Multiprocessor (SMP) servers, (3) workstation clusters, and (4) computational grid environments. This computational framework, E-Cell SessionManager (ESM), is built upon E-Cell System Version 3, a generic software environment for the modeling, simulation, and analysis of whole-cell scale biological systems. Here we introduce the ESM architecture and provide results from benchmark experiments that addressed 2 typical computationally intensive biological problems, (1) a parameter estimation session of a small hypothetical pathway and (2) simulations of a stochastic E. coli heat-shock model with different random number seeds to obtain the statistical characteristics of the stochastic fluctuations.\",\n \"Title: HybGFS: a hybrid method for genome-fingerprint scanning.\\nYear: 2006\\n\\nAbstract: Protein identification based on mass spectrometry (MS) has previously been performed using peptide mass fingerprinting (PMF) or tandem MS (MS/MS) database searching. However, these methods cannot identify proteins that are not already listed in existing databases. Moreover, the alternative approach of de novo sequencing requires costly equipment and the interpretation of complex MS/MS spectra. Thus, there is a need for novel high-throughput protein-identification methods that are independent of existing predefined protein databases.Here, we present a hybrid method for genome-fingerprint scanning, known as HybGFS. This technique combines genome sequence-based peptide MS/MS ion searching with liquid-chromatography elution-time (LC-ET) prediction, to improve the reliability of identification. The hybrid method allows the simultaneous identification and mapping of proteins without a priori information about their coding sequences. The current study used standard LC-MS/MS data to query an in silico-generated six-reading-frame translation and the enzymatic digest of an entire genome. Used in conjunction with precursor/product ion-mass searching, the LC-ETs increased confidence in the peptide-identification process and reduced the number of false-positive matches. The power of this method was demonstrated using recombinant proteins from the Escherichia coli K12 strain.The novel hybrid method described in this study will be useful for the large-scale experimental confirmation of genome coding sequences, without the need for transcriptome-level expression analysis or costly MS database searching.\",\n \"Title: Towards the systematic discovery of signal transduction networks using phosphorylation dynamics data.\\nYear: 2010\\n\\nAbstract: Phosphorylation is a ubiquitous and fundamental regulatory mechanism that controls signal transduction in living cells. The number of identified phosphoproteins and their phosphosites is rapidly increasing as a result of recent mass spectrometry-based approaches.We analyzed time-course phosphoproteome data obtained previously by liquid chromatography mass spectrometry with the stable isotope labeling using amino acids in cell culture (SILAC) method. This provides the relative phosphorylation activities of digested peptides at each of five time points after stimulating HeLa cells with epidermal growth factor (EGF). We initially calculated the correlations between the phosphorylation dynamics patterns of every pair of peptides and connected the strongly correlated pairs to construct a network. We found that peptides extracted from the same intracellular fraction (nucleus vs. cytoplasm) tended to be close together within this phosphorylation dynamics-based network. The network was then analyzed using graph theory and compared with five known signal-transduction pathways. The dynamics-based network was correlated with known signaling pathways in the NetPath and Phospho.ELM databases, and especially with the EGF receptor (EGFR) signaling pathway. Although the phosphorylation patterns of many proteins were drastically changed by the EGF stimulation, our results suggest that only EGFR signaling transduction was both strongly activated and precisely controlled.The construction of a phosphorylation dynamics-based network provides a useful overview of condition-specific intracellular signal transduction using quantitative time-course phosphoproteome data under specific experimental conditions. Detailed prediction of signal transduction based on phosphoproteome dynamics remains challenging. However, since the phosphorylation profiles of kinase-substrate pairs on the specific pathway were localized in the dynamics-based network, our method will be a complementary strategy to explore new components of protein signaling pathways in combination with previous methods (including software) of predicting direct kinase-substrate relationships.\",\n \"Title: GEMBASSY: an EMBOSS associated software package for comprehensive genome analyses.\\nYear: 2013\\n\\nAbstract: The popular European Molecular Biology Open Software Suite (EMBOSS) currently contains over 400 tools used in various bioinformatics researches, equipped with sophisticated development frameworks for interoperability and tool discoverability as well as rich documentations and various user interfaces. In order to further strengthen EMBOSS in the fields of genomics, we here present a novel EMBOSS associated software (EMBASSY) package named GEMBASSY, which adds more than 50 analysis tools from the G-language Genome Analysis Environment and its Representational State Transfer (REST) and SOAP web services. GEMBASSY basically contains wrapper programs of G-language REST/SOAP web services to provide intuitive and easy access to various annotations within complete genome flatfiles, as well as tools for analyzing nucleic composition, calculating codon usage, and visualizing genomic information. For example, analysis methods such as for calculating distance between sequences by genomic signatures and for predicting gene expression levels from codon usage bias are effective in the interpretation of meta-genomic and meta-transcriptomic data. GEMBASSY tools can be used seamlessly with other EMBOSS tools and UNIX command line tools. The source code written in C is available from GitHub (https://github.com/celery-kotone/GEMBASSY/) and the distribution package is freely available from the GEMBASSY web site (http://www.g-language.org/gembassy/).\",\n \"Title: The E-CELL project: Towards integrative simulation of cellular processes\\nYear: 2000\\n\\nAbstract: The E-CELL project was launched in 1996 at Keio University in order to model and simulate various cellular processes with the ultimate goal of simulating the cell as a whole. The first version of the E-CELL simulation system, which is a generic software package for cell modeling, was completed in 1997. The E-CELL system enables us to model not only metabolic pathways but also other higher-order cellular processes such as protein synthesis and membrane transport within the same framework. These various processes can then be integrated into a single simulation model. Using the E-CELL system, we have successfully constructed a virtual cell with 127 genes sufficient for \\\"self-support\\\". The gene set was selected from the genome of Mycoplasma genitalium, the organism having the smallest known genome. The set includes genes for transcription, translation, the glycolysis pathway for energy production, membrane transport, and the phospholipid biosynthesis pathway for membrane structure. The E-CELL system has been made available for beta testing from our website (http://www.e-cell.org).\",\n \"Title: The E-CELL project: towards integrative simulation of cellular processes\\nYear: 2000\\n\\nAbstract: The E-CELL project was launched in 1996 at Keio University in order to model and simulate various cellular processes with the ultimate goal of simulating the cell as a whole. The first version of the E-CELL simulation system, which is a generic software package for cell modeling, was completed in 1997. The E-CELL system enables us to model not only metabolic pathways but also other higher-order cellular processes such as protein synthesis and membrane transport within the same framework. These various processes can then be integrated into a single simulation model.Using the E-CELL system, we have successfully constructed a virtual cell with 127 genes sufficient for “self-support”. The gene set was selected from the genome of Mycoplasma genitalium the organism having the smallest known genome. The set includes genes for transcription, translation, the glycolysis pathway for energy production, membrane transport, and the phospholipid biosynthesis pathway for membrane structure.The E-CELL system has been made available for beta testing from our website (http: //www.e-cell.org).\",\n \"Title: Computational analysis suggests that alternative first exons are involved in tissue-specific transcription in rice (Oryza sativa).\\nYear: 2005\\n\\nAbstract: Transcription start site selection and alternative splicing greatly contribute to diversifying gene expression. Recent studies have revealed the existence of alternative first exons, but most have involved mammalian genes, and as yet the regulation of usage of alternative first exons has not been clarified, especially in plants.We systematically identified putative alternative first exon transcripts in rice, verified the candidates using RT-PCR, and searched for the promoter elements that might regulate the alternative first exons. As a result, we detected a number of unreported alternative first exons, some of which are regulated in a tissue-specific manner.http://www.bioinfo.sfc.keio.ac.jp/research/intron.\",\n \"Title: Comparison of metabolite production capability indices generated by network analysis methods.\\nYear: 2008\\n\\nAbstract: A framework of constraint-based reconstruction and analysis (COBRA) is used for modeling large-scale metabolic networks. In COBRA, extreme pathway and optimization analyses are commonly used to study the properties of networks.\",\n \"Title: Characterization of the splice sites in GT-AG and GC-AG introns in higher eukaryotes using full-length cDNAs.\\nYear: 2004\\n\\nAbstract: For the purpose of analyzing the relation between the splice sites and the order of introns, we conducted the following analysis for the GT-AG and GC-AG splice site groups. First, the pre-mRNAs of H. sapiens, M. musculus, D. melanogaster, A. thaliana and O. sativa were sampled by mapping the full-length cDNA to the genomes. Next, the consensus sequences at different regions of pre-mRNAs were analyzed in the five species. We also investigated the mononucleotide and dinucleotide frequencies in the extensive regions around the 5' splice sites (5'ss) and 3' splice sites (3'ss). As a result, differential frequencies of nucleotides at the first 5'ss in both the GT-AG and GC-AG splice site groups were observed in A. thaliana and O. sativa pre-mRNAs. The trend, which indicates that GC 5'ss possess strong consensus sequences, was observed not only in mammalian pre-mRNAs but also in the pre-mRNAs of D. melanogaster, A. thaliana and O. sativa. Furthermore, we examined the consensus sequences of the constitutive and alternative splice sites. It was suggested that in the case of the alternative GC-AG introns, the tendency to have a weak consensus sequence at 5'ss is different between H. sapiens and M. musculus pre-mRNAs.\",\n \"Title: Time-resolved metabolomics reveals metabolic modulation in rice foliage.\\nYear: 2008\\n\\nAbstract: To elucidate the interaction of dynamics among modules that constitute biological systems, comprehensive datasets obtained from \\\"omics\\\" technologies have been used. In recent plant metabolomics approaches, the reconstruction of metabolic correlation networks has been attempted using statistical techniques. However, the results were unsatisfactory and effective data-mining techniques that apply appropriate comprehensive datasets are needed.Using capillary electrophoresis mass spectrometry (CE-MS) and capillary electrophoresis diode-array detection (CE-DAD), we analyzed the dynamic changes in the level of 56 basic metabolites in plant foliage (Oryza sativa L. ssp. japonica) at hourly intervals over a 24-hr period. Unsupervised clustering of comprehensive metabolic profiles using Kohonen's self-organizing map (SOM) allowed classification of the biochemical pathways activated by the light and dark cycle. The carbon and nitrogen (C/N) metabolism in both periods was also visualized as a phenotypic linkage map that connects network modules on the basis of traditional metabolic pathways rather than pairwise correlations among metabolites. The regulatory networks of C/N assimilation/dissimilation at each time point were consistent with previous works on plant metabolism. In response to environmental stress, glutathione and spermidine fluctuated synchronously with their regulatory targets. Adenine nucleosides and nicotinamide coenzymes were regulated by phosphorylation and dephosphorylation. We also demonstrated that SOM analysis was applicable to the estimation of unidentifiable metabolites in metabolome analysis. Hierarchical clustering of a correlation coefficient matrix could help identify the bottleneck enzymes that regulate metabolic networks.Our results showed that our SOM analysis with appropriate metabolic time-courses effectively revealed the synchronous dynamics among metabolic modules and elucidated the underlying biochemical functions. The application of discrimination of unidentified metabolites and the identification of bottleneck enzymatic steps even to non-targeted comprehensive analysis promise to facilitate an understanding of large-scale interactions among components in biological systems.\",\n \"Title: Can complex cellular processes be governed by simple linear rules?\\nYear: 2009\\n\\nAbstract: Complex living systems have shown remarkably well-orchestrated, self-organized, robust, and stable behavior under a wide range of perturbations. However, despite the recent generation of high-throughput experimental datasets, basic cellular processes such as division, differentiation, and apoptosis still remain elusive. One of the key reasons is the lack of understanding of the governing principles of complex living systems. Here, we have reviewed the success of perturbation-response approaches, where without the requirement of detailed in vivo physiological parameters, the analysis of temporal concentration or activation response unravels biological network features such as causal relationships of reactant species, regulatory motifs, etc. Our review shows that simple linear rules govern the response behavior of biological networks in an ensemble of cells. It is daunting to know why such simplicity could hold in a complex heterogeneous environment. Provided physical reasons can be explained for these phenomena, major advancement in the understanding of basic cellular processes could be achieved.\",\n \"Title: G-language genome analysis environment with REST and SOAP web service interfaces.\\nYear: 2010\\n\\nAbstract: G-language genome analysis environment (G-language GAE) contains more than 100 programs that focus on the analysis of bacterial genomes, including programs for the identification of binding sites by means of information theory, analysis of nucleotide composition bias and the distribution of particular oligonucleotides, calculation of codon bias and prediction of expression levels, and visualization of genomic information. We have provided a collection of web services for these programs by utilizing REST and SOAP technologies. The REST interface, available at http://rest.glanguage.org/, provides access to all 145 functions of the G-language GAE. These functions can be accessed from other online resources. All analysis functions are represented by unique universal resource identifiers. Users can access the functions directly via the corresponding universe resource locators (URLs), and biological web sites can readily embed the functions by simply linking to these URLs. The SOAP services, available at http://www.g-language.org/wiki/soap/, provide language-independent programmatic access to 77 analysis programs. The SOAP service Web Services Definition Language file can be readily loaded into graphical clients such as the Taverna workbench to integrate the programs with other services and workflows.\",\n \"Title: Mmmdb: Mouse Multiple Tissue Metabolome Database\\nYear: 2012\\n\\nAbstract: The Mouse Multiple Tissue Metabolome Database (MMMDB) provides comprehensive and quantitative metabolomic information for multiple tissues from single mice. Manually curated databases that integrate literature-based individual metabolite information have been available so far. However, data sets on the absolute concentration of a single metabolite integrated from multiple resources are often difficult to be used when different metabolomic studies are compared because the relative balance of the multiple metabolite concentrations in the metabolic pathways as a snapshot of a dynamic system is more important than the absolute concentration of a single metabolite. We developed MMMDB by performing non-targeted analyses of cerebra, cerebella, thymus, spleen, lung, liver, kidney, heart, pancreas, testis and plasma using capillary electrophoresis time-of-flight mass spectrometry and detected 428 non-redundant features from which 219 metabolites were successfully identified. Quantified concentrations of the individual metabolites and the corresponding processed raw data; for example, the electropherograms and mass spectra with their annotations, such as isotope and fragment information, are stored in the database. MMMDB is designed to normalize users' data, which can be submitted online and used to visualize overlaid electropherograms. Thus, MMMDB allows newly measured data to be compared with the other data in the database. MMMDB is available at: http://mmmdb.iab.keio.ac.jp.\",\n \"Title: Aligning LC peaks by converting gradient retention times to retention index of peptides in proteomic experiments.\\nYear: 2008\\n\\nAbstract: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful tool in proteomics studies, but when peptide retention information is used for identification purposes, it remains challenging to compare multiple LC-MS/MS runs or to match observed and predicted retention times, because small changes of LC conditions unavoidably lead to variability in retention times. In addition, non-contiguous retention data obtained with different LC-MS instruments or in different laboratories must be aligned to confirm and utilize rapidly accumulating published proteomics data.We have developed a new alignment method for peptide retention times based on linear solvent strength (LSS) theory. We found that log k(0) (logarithm of retention factor for a given organic solvent) in the LSS theory can be utilized as a 'universal' retention index of peptides (RIP) that is independent of LC gradients, and depends solely on the constituents of the mobile phase and the stationary phases. We introduced a machine learning-based scheme to optimize the conversion function of gradient retention times (t(g)) to log k(0). Using the optimized function, t(g) values obtained with different LC-MS systems can be directly compared with each other on the RIP scale. In an examination of Arabidopsis proteomic data, the vast majority of retention time variability was removed, and five datasets obtained with various LC-MS systems were successfully aligned on the RIP scale.\",\n \"Title: Integrative Features Of The Yeast Phosphoproteome And Protein-Protein Interaction Map\\nYear: 2011\\n\\nAbstract: Following recent advances in high-throughput mass spectrometry (MS)-based proteomics, the numbers of identified phosphoproteins and their phosphosites have greatly increased in a wide variety of organisms. Although a critical role of phosphorylation is control of protein signaling, our understanding of the phosphoproteome remains limited. Here, we report unexpected, large-scale connections revealed between the phosphoproteome and protein interactome by integrative data-mining of yeast multi-omics data. First, new phosphoproteome data on yeast cells were obtained by MS-based proteomics and unified with publicly available yeast phosphoproteome data. This revealed that nearly 60% of similar to 6,000 yeast genes encode phosphoproteins. We mapped these unified phosphoproteome data on a yeast protein-protein interaction (PPI) network with other yeast multi-omics datasets containing information about proteome abundance, proteome disorders, literature-derived signaling reactomes, and in vitro substratomes of kinases. In the phospho-PPI, phosphoproteins had more interacting partners than nonphosphoproteins, implying that a large fraction of intracellular protein interaction patterns (including those of protein complex formation) is affected by reversible and alternative phosphorylation reactions. Although highly abundant or unstructured proteins have a high chance of both interacting with other proteins and being phosphorylated within cells, the difference between the number counts of interacting partners of phosphoproteins and nonphosphoproteins was significant independently of protein abundance and disorder level. Moreover, analysis of the phospho-PPI and yeast signaling reactome data suggested that co-phosphorylation of interacting proteins by single kinases is common within cells. These multi-omics analyses illuminate how wide-ranging intracellular phosphorylation events and the diversity of physical protein interactions are largely affected by each other.\",\n \"Title: Multiresolution analysis uncovers hidden conservation of properties in structurally and functionally similar proteins.\\nYear: 2006\\n\\nAbstract: Physicochemcial properties of amino acids are important factors in determining protein structure and function. Most approaches make use of averaged properties over entire domains or even proteins to analyze their structure or function. This level of coarseness tends to hide the richness of the variability in the different properties across functional domains. This paper studies the conservation of physicochemical properties in a functionally similar family of proteins using a novel wavelet-based technique known as multiresolution analysis. Such an analysis can help uncover characteristics that can otherwise remain hidden. We have studied the protein kinase family of sequences and our findings are as follows: (a) a number of different properties are conserved over the functional catalytic domain irrespective of the sequence identities; (b) conservation of properties can be observed at different frequency levels and they agree well with the known structural/functional properties of the subdomains for the protein kinase family; (c) structural differences between the different kinase family members are reflected in the waveforms; and (d) functionally important mutations show distortions in the waveforms of conserved properties. The potential usefulness of the above findings in identifying functionally similar sequences in the twilight and midnight zones is demonstrated through a simple prediction model for the protein kinase family which achieved a recall of 93.7% and a precision of 96.75% in cross-validation tests.\",\n \"Title: Inferring rules of Escherichia coli translational efficiency using an artificial neural network.\\nYear: 2007\\n\\nAbstract: Although the machinery for translation initiation in Escherichia coli is very complicated, the translational efficiency has been reported to be predictable from upstream oligonucleotide sequences. Conventional models have difficulties in their generalization ability and prediction nonlinearity and in their ability to deal with a variety of input attributions. To address these issues, we employed structural learning by artificial neural networks to infer general rules for translational efficiency. The correlation between translational activities measured by biological experiments and those predicted by our method in the test data was significant (r=0.78), and our method uncovered underlying rules of translational activities and sequence patterns from the obtained skeleton structure. The significant rules for predicting translational efficiency were (1) G- and A-rich oligonucleotide sequences, resembling the Shine–Dalgarno sequence, at positions −10 to −7; (2) first base A in the initiation codon; (3) transport/binding or amino acid metabolism gene function; (4) high binding energy between mRNA and 16S rRNA at positions −15 to −5. An additional inferred novel rule was that C at position −1 increases translational efficiency. When our model was applied to the entire genomic sequence of E. coli, translational activities of genes for metabolism and translational were significantly high.\",\n \"Title: emPAI Calc--for the estimation of protein abundance from large-scale identification data by liquid chromatography-tandem mass spectrometry.\\nYear: 2010\\n\\nAbstract: AemPAI Calc is an open-source web application for the estimation of protein abundance. It uses the correlation between the number of identified peptides and protein abundance in mass spectrometry-based proteomic experiments. The program is the first implementation of our previously reported emPAI algorithm; it calculates the emPAI from the protein identification results obtained by database search engines such as Mascot.(TM)\",\n \"Title: Restauro-G: a rapid genome re-annotation system for comparative genomics.\\nYear: 2007\\n\\nAbstract: Annotations of complete genome sequences submitted directly from sequencing projects are diverse in terms of annotation strategies and update frequencies. These inconsistencies make comparative studies difficult. To allow rapid data preparation of a large number of complete genomes, automation and speed are important for genome re-annotation. Here we introduce an open-source rapid genome re-annotation software system, Restauro-G, specialized for bacterial genomes. Restauro-G re-annotates a genome by similarity searches utilizing the BLAST-Like Alignment Tool, referring to protein databases such as UniProt KB, NCBI nr, NCBI COGs, Pfam, and PSORTb. Re-annotation by Restauro-G achieved over 98% accuracy for most bacterial chromosomes in comparison with the original manually curated annotation of EMBL releases. Restauro-G was developed in the generic bioinformatics workbench G-language Genome Analysis Environment and is distributed at http://restauro-g.iab.keio.ac.jp/under the GNU General Public License.\",\n \"Title: KBWS: an EMBOSS associated package for accessing bioinformatics web services.\\nYear: 2011\\n\\nAbstract: The availability of bioinformatics web-based services is rapidly proliferating, for their interoperability and ease of use. The next challenge is in the integration of these services in the form of workflows, and several projects are already underway, standardizing the syntax, semantics, and user interfaces. In order to deploy the advantages of web services with locally installed tools, here we describe a collection of proxy client tools for 42 major bioinformatics web services in the form of European Molecular Biology Open Software Suite (EMBOSS) UNIX command-line tools. EMBOSS provides sophisticated means for discoverability and interoperability for hundreds of tools, and our package, named the Keio Bioinformatics Web Service (KBWS), adds functionalities of local and multiple alignment of sequences, phylogenetic analyses, and prediction of cellular localization of proteins and RNA secondary structures. This software implemented in C is available under GPL from http://www.g-language.org/kbws/ and GitHub repository http://github.com/cory-ko/KBWS. Users can utilize the SOAP services implemented in Perl directly via WSDL file at http://soap.g-language.org/kbws.wsdl (RPC Encoded) and http://soap.g-language.org/kbws_dl.wsdl (Document/literal).\",\n \"Title: Protein complex prediction via verifying and reconstructing the topology of domain-domain interactions.\\nYear: 2010\\n\\nAbstract: High-throughput methods for detecting protein-protein interactions enable us to obtain large interaction networks, and also allow us to computationally identify the associations of proteins as protein complexes. Although there are methods to extract protein complexes as sets of proteins from interaction networks, the extracted complexes may include false positives because they do not account for the structural limitations of the proteins and thus do not check that the proteins in the extracted complex can simultaneously bind to each other. In addition, there have been few searches for deeper insights into the protein complexes, such as of the topology of the protein-protein interactions or into the domain-domain interactions that mediate the protein interactions.Here, we introduce a combinatorial approach for prediction of protein complexes focusing not only on determining member proteins in complexes but also on the DDI/PPI organization of the complexes. Our method analyzes complex candidates predicted by the existing methods. It searches for optimal combinations of domain-domain interactions in the candidates based on an assumption that the proteins in a candidate can form a true protein complex if each of the domains is used by a single protein interaction. This optimization problem was mathematically formulated and solved using binary integer linear programming. By using publicly available sets of yeast protein-protein interactions and domain-domain interactions, we succeeded in extracting protein complex candidates with an accuracy that is twice the average accuracy of the existing methods, MCL, MCODE, or clustering coefficient. Although the configuring parameters for each algorithm resulted in slightly improved precisions, our method always showed better precision for most values of the parameters.Our combinatorial approach can provide better accuracy for prediction of protein complexes and also enables to identify both direct PPIs and DDIs that mediate them in complexes.\",\n \"Title: LR parsers for natural languages\\nYear: 1984\\n\\nAbstract: MLR, an extended LR parser, is introduced, and its application to natural language parsing is discussed. An LR parser is a shift-reduce parser which is deterministically guided by a parsing table. A parsing table can be obtained automatically from a context-free phrase structure grammar. LR parsers cannot manage ambiguous grammars such as natural language grammars, because their parsing tables would have multiply-defined entries, which precludes deterministic parsing. MLR, however, can handle multiply-defined entries, using a dynamic programming method. When an input sentence is ambiguous, the MLR parser produces all possible parse trees without parsing any part of the input sentence more than once in the same way, despite the fact that the parser does not maintain a chart as in chart parsing. Our method also provides an elegant solution to the problem of multi-part-of-speech words such as \\\"that\\\". The MLR parser and its parsing table generator have been implemented at Carnegie-Mellon University.\",\n \"Title: Graph-structured Stack and natural language parsing\\nYear: 1988\\n\\nAbstract: A general device for handling nondeterminism in stack operations is described. The device, called a Graph-structured Stack, can eliminate duplication of operations throughout the nondeterministic processes. This paper then applies the graph-structured stack to various natural language parsing methods, including ATN, LR parsing, categorial grammar and principle-based parsing. The relationship between the graph-structured stack and a chart in chart parsing is also discussed.\",\n \"Title: A microarray data-based semi-kinetic method for predicting quantitative dynamics of genetic networks.\\nYear: 2005\\n\\nAbstract: BACKGROUND: Elucidating the dynamic behaviour of genetic regulatory networks is one of the most significant challenges in systems biology. However, conventional quantitative predictions have been limited to small networks because publicly available transcriptome data has not been extensively applied to dynamic simulation. RESULTS: We present a microarray data-based semi-kinetic (MASK) method which facilitates the prediction of regulatory dynamics of genetic networks composed of recurrently appearing network motifs with reasonable accuracy. The MASK method allows the determination of model parameters representing the contribution of regulators to transcription rate from time-series microarray data. Using a virtual regulatory network and a Saccharomyces cerevisiae ribosomal protein gene module, we confirmed that a MASK model can predict expression profiles for various conditions as accurately as a conventional kinetic model. CONCLUSION: We have demonstrated the MASK method for the construction of dynamic simulation models of genetic networks from time-series microarray data, initial mRNA copy number and first-order degradation constants of mRNA. The quantitative accuracy of the MASK models has been confirmed, and the results indicated that this method enables the prediction of quantitative dynamics in genetic networks composed of commonly used network motifs, which cover considerable fraction of the whole network.\",\n \"Title: SPLITS: A New Program for Predicting Split and Intron-Containing tRNA Genes at the Genome Level.\\nYear: 2006\\n\\nAbstract: In the archaea, some tRNA precursors contain intron(s) not only in the anticodon loop region but also in diverse sites of the gene (intron-containing tRNA or cis-spliced tRNA). The parasite Nanoarchaeum equitans, a member of the Nanoarchaeota kingdom, creates functional tRNA from separate genes, one encoding the 5'-half and the other the 3'-half (split tRNA or trans-spliced tRNA). Although recent genome projects have revealed a huge amount of nucleotide sequence data in the archaea, a comprehensive methodology for intron-containing and split tRNA searching is yet to be established. We therefore developed SPLITS, which is aimed at searching for any type of tRNA gene and is especially focused on intron-containing tRNAs or split tRNAs at the genome level. SPLITS initially predicts the bulge-helix-bulge splicing motif (a well-known, required structure in archaeal pre-tRNA introns) to determine and remove the intronic regions of tRNA genes. The intron-removed DNA sequences are automatically queried to tRNAscan-SE. SPLITS can predict known tRNAs with single introns located at unconventional sites on the genes (100%), tRNAs with double introns (85.7%), and known split tRNAs (100%). Our program will be very useful for identifying novel tRNA genes after completion of genome projects. The SPLITS source code is freely downloadable at http://splits.iab.keio.ac.jp/.\",\n \"Title: Robust effects of Tsr-CheBp and CheA-CheYp affinity in bacterial chemotaxis.\\nYear: 2007\\n\\nAbstract: Cell motility and chemotaxis play a role in the virulence of pathogenic bacteria, such as escape from host immune responses. Escherichia coli chemotaxis provides a well-characterized model system for the bacterial chemotaxis network. Two features of E. coli chemotaxis include signal amplification and robustly accurate adaptation. Recent simulation studies with models considering the effects of other receptors have suggested possible mechanisms for signal amplification. Although precise adaptation to aspartate has been explained by conventional kinetic models, the adaptation behavior of models incorporating the effects of other receptors remains unclear.We concentrated on how receptor crosstalk affects minimization of adaptation error and compared models in which the contribution of other receptors varied.We demonstrated that the model is adaptable to attractant concentrations ranging from 0.1microM to 10mM with a decreased error rate (from 8% to 2%) when the kinetic constant of CheA and phosphorylated CheY dissociation is increased.The results suggest that accurate adaptation is maintained through control of both the interaction of cytoplasmic Che proteins and the activity of the receptor complex.\",\n \"Title: Measure of synonymous codon usage diversity among genes in bacteria.\\nYear: 2009\\n\\nAbstract: In many bacteria, intragenomic diversity in synonymous codon usage among genes has been reported. However, no quantitative attempt has been made to compare the diversity levels among different genomes. Here, we introduce a mean dissimilarity-based index (Dmean) for quantifying the level of diversity in synonymous codon usage among all genes within a genome.The application of Dmean to 268 bacterial genomes shows that in bacteria with extremely biased genomic G+C compositions there is little diversity in synonymous codon usage among genes. Furthermore, our findings contradict previous reports. For example, a low level of diversity in codon usage among genes has been reported for Helicobacter pylori, but based on Dmean, the diversity level of this species is higher than those of more than half of bacteria tested here. The discrepancies between our findings and previous reports are probably due to differences in the methods used for measuring codon usage diversity.We recommend that Dmean be used to measure the diversity level of codon usage among genes. This measure can be applied to other compositional features such as amino acid usage and dinucleotide relative abundance as a genomic signature.\",\n \"Title: Computational analysis of stop codon readthrough in D.melanogaster.\\nYear: 2003\\n\\nAbstract: Motivation: Readthrough is an unusual process in which a stop codon is misread or skipped. Recently it has been shown that some translation is regulated by the readthrough reactions although the complete mechanism is not clear. Therefore, the discovery of 'readthrough genes' is important for further investigation of their cellular roles, which may provide additional insights into the mechanism of translational regulation. Results: We constructed a system that lists candidates of readthrough genes based on the existence of a 'protein motif' at the 3' untranslated region (UTR). Using this system, we extracted 85 candidates from 4082 nucleic acid sequences of Drosophila melanogaster in GenBank database. The sequences of these candidates had a slightly more stable secondary structure and different base preferences compared to the non-candidates. As these features are known to have an effect on readthrough events, we would like to suggest that these candidates contain actual readthrough genes.\",\n \"Title: Visualization of three-way comparisons of omics data.\\nYear: 2007\\n\\nAbstract: Density plot visualizations (also referred to as heat maps or color maps) are widely used in different fields including large-scale omics studies in biological sciences. However, the current color-codings limit the visualizations to single datasets or pairwise comparisons.We propose a color-coding approach for the representation of three-way comparisons. The approach is based on the HSB (hue, saturation, brightness) color model. The three compared values are assigned specific hue values from the circular hue range (e.g. red, green, and blue). The hue value representing the three-way comparison is calculated according to the distribution of three compared values. If two of the values are identical and one is different, the resulting hue is set to the characteristic hue of the differing value. If all three compared values are different, the resulting hue is selected from a color gradient running between the hues of the two most distant values (as measured by the absolute value of their difference) according to the relative position of the third value between the two. The saturation of the color representing the three-way comparison reflects the amplitude (or extent) of the numerical difference between the two most distant values according to a scale of interest. The brightness is set to a maximum value by default but can be used to encode additional information about the three-way comparison.We propose a novel color-coding approach for intuitive visualization of three-way comparisons of omics data.\",\n \"Title: Integrative modeling of gene expression and metabolism with E-CELL System\\nYear: 2002\\n\\nAbstract: A gene-expression model for an E-CELL simulation was constructed, and the simulation was carried out. The model was integrated\\n with a metabolism model of the self-sustaining virtual cell model which was constructed based on aMycoplasma genitalium cell. Details of the model structure and the results of the simulation are shown. AnEscherichia coli lac-operon model was also constructed by integrating and abstracting the gene-expression model. Wherever possible, experimental\\n parameters were used to construct the model\",\n \"Title: A general computational model of mitochondrial metabolism in a whole organelle scale.\\nYear: 2004\\n\\nAbstract: A computational tool for mitochondrial systems biology has been developed as a simulation model of E-Cell2, a publicly available simulation system. The general model consists of 58 enzymatic reactions and 117 metabolites, representing the respiratory chain, the TCA cycle, the fatty acid beta-oxidation and the inner-membrane transport system. It is based on previously published enzyme kinetics studies in the literature; we have successfully integrated and packaged them into a single large model. The model can be easily extended and modified so that mitochondrial biologists/physiologists can integrate their own models and evaluate them in the context of the whole organelle metabolism.The mitochondrial model is bundled up with E-Cell2 simulation system, which can be downloaded from http://www.e-cell.org. CD-ROMs are also available and are distributed at major conferences.All the kinetic data are available via http://www.e-cell.org\",\n \"Title: Another stride towards knowledge-based machine translation\\nYear: 1986\\n\\nAbstract: Building on the well-established premise that reliable machine translation requires a significant degree of text comprehension, this paper presents a recent advance in multi-lingual knowledge-based machine translation (KBMT). Unlike previous approaches, the current method provides for separate syntactic and semantic knowledge sources that are integrated dynamically for parsing and generation. Such a separation enables the system to have syntactic grammars, language specific but domain general, and semantic knowledge bases, domain specific but language general. Subsequently, grammars and domain knowledge are precompiled automatically in any desired combination to produce very efficient and very thorough real-time parsers. A pilot implementation of our KBMT architecture using functional grammars and entity-oriented semantics demonstrates the feasibility of the new approach.1\",\n \"Title: KEGG-Based Pathway Visualization Tool for Complex Omics Data.\\nYear: 2005\\n\\nAbstract: Pathway-level visualization of omics data provides an essential means for systems biology, to capture the systematic properties of the inner activities of cells. Here we describe a web-based resource consisting of a web-application for the visualization of complex omics data onto KEGG pathways to overview all entities in the context of cellular pathways, and databases created with the software to visualize a series of microarray data. The web-application accepts transcriptome, proteome, metabolome, or the combination of these data as input, and because of this scalability it is advantageous for the visualization of cell simulation results. The web server can be accessed at http://www.g-language.org/data/marray/.\",\n \"Title: GEM System: automatic prototyping of cell-wide metabolic pathway models from genomes.\\nYear: 2006\\n\\nAbstract: Successful realization of a \\\"systems biology\\\" approach to analyzing cells is a grand challenge for our understanding of life. However, current modeling approaches to cell simulation are labor-intensive, manual affairs, and therefore constitute a major bottleneck in the evolution of computational cell biology.We developed the Genome-based Modeling (GEM) System for the purpose of automatically prototyping simulation models of cell-wide metabolic pathways from genome sequences and other public biological information. Models generated by the GEM System include an entire Escherichia coli metabolism model comprising 968 reactions of 1195 metabolites, achieving 100% coverage when compared with the KEGG database, 92.38% with the EcoCyc database, and 95.06% with iJR904 genome-scale model.The GEM System prototypes qualitative models to reduce the labor-intensive tasks required for systems biology research. Models of over 90 bacterial genomes are available at our web site.\",\n \"Title: The Integration of Unification-Based Syntax/Semantics and Memory-Based Pragmatics for Real-Time Understanding of Noisy Continuous Speech Input\\nYear: 1988\\n\\nAbstract: Real-time understanding of speech input is difficult especially because the input is often noisy and elliptic. Multiple morphophonemic and lexical hypotheses generated for a single input sentence cannot be resolved by local semantics alone. We have developed a system in which unilication-based parsing of speech input is integrated with thematic memory-based spreading activation that supplies extra-sentential knowledge that can help to disambiguate noisy and elliptic real-time speaker-independent continuous speech input.\",\n \"Title: Variation in the correlation of G + C composition with synonymous codon usage bias among bacteria.\\nYear: 2007\\n\\nAbstract: G + C composition at the third codon position (GC3) is widely reported to be correlated with synonymous codon usage bias. However, no quantitative attempt has been made to compare the extent of this correlation among different genomes. Here, we applied Shannon entropy from information theory to measure the degree of GC3 bias and that of synonymous codon usage bias of each gene. The strength of the correlation of GC3 with synonymous codon usage bias, quantified by a correlation coefficient, varied widely among bacterial genomes, ranging from -0.07 to 0.95. Previous analyses suggesting that the relationship between GC3 and synonymous codon usage bias is independent of species are thus inconsistent with the more detailed analyses obtained here for individual species.\",\n \"Title: eXpanda: An Integrated Platform for Network Analysis and Visualization.\\nYear: 2007\\n\\nAbstract: Analysis and visualization of biological networks, such as protein-protein and protein-DNA interactions, are crucially important toward obtaining a thorough understanding of living systems. Here, we present an integrative software platform, eXpanda, which enables an analysis of a very broad range of biological networks, with a special focus on the extraction of characteristic topologies which potentially function as units in the networks. eXpanda is provided as a Perl library which gives full-automatic connections to various biological databases via a Perl programmable interface and can perform topological analysis based on graph theory. The results of these analyses are visualizable by vector graphics. eXpanda is under GNU General Public License. Software package, detailed documentations, source codes, and some sample scripts are downloadable at http://medcd.iab.keio.ac.jp/expanda/.\",\n \"Title: Prediction of axillary lymph node metastasis in primary breast cancer patients using a decision tree-based model.\\nYear: 2012\\n\\nAbstract: The aim of this study was to develop a new data-mining model to predict axillary lymph node (AxLN) metastasis in primary breast cancer. To achieve this, we used a decision tree-based prediction method-the alternating decision tree (ADTree).Clinical datasets for primary breast cancer patients who underwent sentinel lymph node biopsy or AxLN dissection without prior treatment were collected from three institutes (institute A, n = 148; institute B, n = 143; institute C, n = 174) and were used for variable selection, model training and external validation, respectively. The models were evaluated using area under the receiver operating characteristics (ROC) curve analysis to discriminate node-positive patients from node-negative patients.The ADTree model selected 15 of 24 clinicopathological variables in the variable selection dataset. The resulting area under the ROC curve values were 0.770 [95% confidence interval (CI), 0.689-0.850] for the model training dataset and 0.772 (95% CI: 0.689-0.856) for the validation dataset, demonstrating high accuracy and generalization ability of the model. The bootstrap value of the validation dataset was 0.768 (95% CI: 0.763-0.774).Our prediction model showed high accuracy for predicting nodal metastasis in patients with breast cancer using commonly recorded clinical variables. Therefore, our model might help oncologists in the decision-making process for primary breast cancer patients before starting treatment.\",\n \"Title: Dynamic modeling of genetic networks using genetic algorithm and S-system.\\nYear: 2003\\n\\nAbstract: Motivation: The modeling of system dynamics of genetic networks, metabolic networks or signal transduction cascades from time-course data is formulated as a reverse-problem. Previous studies focused on the estimation of only network structures, and they were ineffective in inferring a network structure with feedback loops. We previously proposed a method to predict not only the network structure but also its dynamics using a Genetic Algorithm (GA) and an S-system formalism. However, it could predict only a small number of parameters and could rarely obtain essential structures. In this work, we propose a unified extension of the basic method. Notable improvements are as follows: (1) an additional term in its evaluation function that aims at eliminating futile parameters; (2) a crossover method called Simplex Crossover (SPX) to improve its optimization ability; and (3) a gradual optimization strategy to increase the number of predictable parameters. Results: The proposed method is implemented as a C program called PEACE1 (Predictor by Evolutionary Algorithms and Canonical Equations 1). Its performance was compared with the basic method. The comparison showed that: (1) the convergence rate increased about 5-fold; (2) the optimization speed was raised about 1.5-fold; and (3) the number of predictable parameters was increased about 5-fold. Moreover, we successfully inferred the dynamics of a small genetic network constructed with 60 parameters for 5 network variables and feedback loops using only time-course data of gene expression.\",\n \"Title: Comparative study of circadian oscillatory network models of Drosophila.\\nYear: 2008\\n\\nAbstract: The circadian clock of Drosophila is a model pathway for research in biological clock mechanisms, both with traditional experimental approaches and with emerging systems biology approaches utilizing mathematical modeling and in silico computer simulation. Dynamic diurnal oscillations are achieved by the complex interaction of components as a system, and mathematical reconstruction has proven to be an invaluable means of understanding such systematic behavior. In this study, we implemented eight published models of the Drosophila circadian clock in Systems Biology Markup Language (SBML) for comparative systems biology studies using E-Cell Simulation Environment version 3, to examine the system-level requirements for the clock mechanism to be robust, by calculating the period and amplitude sensitivity coefficients with simulation experiments. While all models were generally robust as determined by the network topology of the oscillatory feedback loop structure, existing models place relatively strong emphasis on transcription regulation, although this is a limitation on robustness. We suggest that more comprehensive modeling including protein phosphorylation, polymerization, and nuclear transport with regard to amplitude sensitivity will be necessary for understanding the light entrainment and temperature compensation of circadian clocks.\",\n \"Title: A multi-algorithm, multi-timescale method for cell simulation.\\nYear: 2004\\n\\nAbstract: Many important problems in cell biology require the dense nonlinear interactions between functional modules to be considered. The importance of computer simulation in understanding cellular processes is now widely accepted, and a variety of simulation algorithms useful for studying certain subsystems have been designed. Many of these are already widely used, and a large number of models constructed on these existing formalisms are available. A significant computational challenge is how we can integrate such sub-cellular models running on different types of algorithms to construct higher order models.A modular, object-oriented simulation meta-algorithm based on a discrete-event scheduler and Hermite polynomial interpolation has been developed and implemented. It is shown that this new method can efficiently handle many components driven by different algorithms and different timescales. The utility of this simulation framework is demonstrated further with a 'composite' heat-shock response model that combines the Gillespie-Gibson stochastic algorithm and deterministic differential equations. Dramatic improvements in performance were obtained without significant accuracy drawbacks. A multi-timescale demonstration of coupled harmonic oscillators is also shown.\",\n \"Title: The universal parser architecture for knowledge-based machine translation\\nYear: 1987\\n\\nAbstract: Machine translation should be semanticalty-accurate, linguistically-principled, user-interactive, and extensible to multiple languages and domains. This paper presents the universal parser architecture that strives to meet these objectives. In essence, linguistic knowledge bases (syntactic, semantic, lexical, pragmatic), encoded in theoretically-motivated formalisms such as lexical-functional grammars, are unified and precompiled into fast run-time grammars for parsing and generation. Thus, the universal parser provides principled run-time integration of syntax and semantics, while preserving the generality of domain-independent syntactic grammars, and language-independent domain knowledge bases; the optimized cross product is generated automatically in the precornpllation phase. Initial results for bi-directional English-Japanese translation show considerable promise both in terms of demonstrating the theoretical feasibillty of the approach and in terms of subsequent practical utility.\",\n \"Title: Genome Projector: zoomable genome map with multiple views.\\nYear: 2009\\n\\nAbstract: Molecular biology data exist on diverse scales, from the level of molecules to -omics. At the same time, the data at each scale can be categorised into multiple layers, such as the genome, transcriptome, proteome, metabolome, and biochemical pathways. Due to the highly multi-layer and multi-dimensional nature of biological information, software interfaces for database browsing should provide an intuitive interface that allows for rapid migration across different views and scales. The Zoomable User Interface (ZUI) and tabbed browsing have proven successful for this purpose in other areas, especially to navigate the vast information in the World Wide Web.This paper presents Genome Projector, a Web-based gateway for genomics information with a zoomable user interface using Google Maps API, equipped with four seamlessly accessible and searchable views: a circular genome map, a traditional genome map, a biochemical pathways map, and a DNA walk map. The Web application for 320 bacterial genomes is available at http://www.g-language.org/GenomeProjector/. All data and software including the source code, documentations, and development API are freely available under the GNU General Public License. Zoomable maps can be easily created from any image file using the development API, and an online data mapping service for Genome Projector is also available at our Web site.Genome Projector is an intuitive Web application for browsing genomics information, implemented with a zoomable user interface and tabbed browsing utilising Google Maps API and Asynchronous JavaScript and XML (AJAX) technology.\",\n \"Title: GeNESiS: gene network evolution simulation software.\\nYear: 2008\\n\\nAbstract: Background: There has been a lot of interest in recent years focusing on the modeling and simulation of Gene Regulatory Networks (GRNs). However, the evolutionary mechanisms that give rise to GRNs in the first place are still largely unknown. In an earlier work, we developed a framework to analyze the effect of objective functions, input types and starting populations on the evolution of GRNs with a specific emphasis on the robustness of evolved GRNs. Results: In this work, we present a parallel software package, GeNESiS for the modeling and simulation of the evolution of gene regulatory networks (GRNs). The software models the process of gene regulation through a combination of finite-state and stochastic models. The evolution of GRNs is then simulated by means of a genetic algorithm with the network connections represented as binary strings. The software allows users to simulate the evolution under varying selective pressures and starting conditions. We believe that the software provides a way for researchers to understand the evolutionary behavior of populations of GRNs. Conclusion: We believe that GeNESiS will serve as a useful tool for scientists interested in understanding the evolution of gene regulatory networks under a range of different conditions and selective pressures. Such modeling efforts can lead to a greater understanding of the network characteristics of GRNs.\",\n \"Title: Consideration On Contact Mechanism Of Ybacuo Bulk Superconductor With Deposited Metal Layer\\nYear: 2007\\n\\nAbstract: A persistent current switch (PCS) is used for superconducting applications, such as superconducting magnetic energy storage (SMES) system. The authors have proposed a mechanical switch of Y-Ba-Cu-0 (YBCO) bulk as a mechanical PCS. In previous study, the authors have successfully reduced a residual resistance by depositing with metal on contact surface. This paper focused on a current carrying area (called a-spot) on contact surface and presented an effect of deposited metal on electrical contact characteristics in order to clear the contact mechanism. As the results of experiments and simulation using FEM, it became clear that it was effective for reducing the residual resistance from a view point of increasing the a-spot by depositing with metal.\",\n \"Title: An efficient augmented-context-free parsing algorithm\\nYear: 1987\\n\\nAbstract: An efficient parsing algorithm for augmented context-free grammars is introduced, and its application to on-line natural language interfaces discussed. The algorithm is a generalized LR parsing algorithm, which precomputes an LR shift-reduce parsing table (possibly with multiple entries) from a given augmented context-free grammar. Unlike the standard LR parsing algorithm, it can handle arbitrary context-free grammars, including ambiguous grammars, while most of the LR efficiency is preserved by introducing the concept of a \\\"graph-structured stack\\\". The graph-structured stack allows an LR shift-reduce parser to maintain multiple parses without parsing any part of the input twice in the same way. We can also view our parsing algorithm as an extended chart parsing algorithm efficiently guided by LR parsing tables. The algorithm is fast, due to the LR table precomputation. In several experiments with different English grammars and sentences, timings indicate a five- to tenfold speed advantage over Earley's context-free parsing algorithm.The algorithm parses a sentence strictly from left to right on-line, that is, it starts parsing as soon as the user types in the first word of a sentence, without waiting for completion of the sentence. A practical on-line parser based on the algorithm has been implemented in Common Lisp, and running on Symbolics and HP AI workstations. The parser is used in the multi-lingual machine translation project at CMU. Also, a commercial on-line parser for Japanese language is being built by Intelligent Technology Incorporation, based on the technique developed at CMU.\",\n \"Title: MEGU: Pathway Mapping Web-Service Based on KEGG and SVG.\\nYear: 2006\\n\\nAbstract: Scientific visualization is a key technology to enhance our understanding of huge masses of omics data, especially for cell-wide, high-throughput measurements of the physiological networks. We have developed a web application that visualizes complex omics data of multiple layers simultaneously, including transcriptome, proteome, and metabolome, onto an integrated pathway diagram derived by connecting the individual KEGG pathway maps; the mapped images are generated in Scalable Vector Graphics for easy editing by hand or with computer programs or drawing software. The web application is available at http://megu.iab.keio.ac.jp/.\",\n \"Title: Construction of a biological tissue model based on a single-cell model: a computer simulation of metabolic heterogeneity in the liver lobule.\\nYear: 2008\\n\\nAbstract: An enormous body of information has been obtained by molecular and cellular biology in the last half century. However, even these powerful approaches are not adequate when it comes to higher-level biological structures, such as tissues, organs, and individual organisms, because of the complexities involved. Thus, accumulation of data at the higher levels supports and broadens the context for that obtained on the molecular and cellular levels. Under such auspices, an attempt to elucidate mesoscopic and macroscopic subjects based on plentiful nanoscopic and microscopic data is of great potential value. On the other hand, fully realistic simulation is impracticable because of the extensive cost entailed and enormous amount of data required. Abstraction and modeling that balance the dual requirements of prediction accuracy and manageable calculation cost are of great importance for systems biology. We have constructed an ammonia metabolism model of the hepatic lobule, a histological component of the liver, based on a single-hepatocyte model that consists of the biochemical kinetics of enzymes and transporters. To bring the calculation cost within reason, the porto-central axis, which is an elemental structure of the lobule, is defined as the systems biological unit of the liver, and is accordingly modeled. A model including both histological structure and position-specific gene expression of major enzymes largely represents the physiological dynamics of the hepatic lobule in nature. In addition, heterogeneous gene expression is suggested to have evolved to optimize the energy efficiency of ammonia detoxification at the macroscopic level, implying that approaches like this may elucidate how properties at the molecular and cellular levels, such as regulated gene expression, modify higher-level phenomena of multicellular tissue, organs, and organisms.\",\n \"Title: A web server for interactive and zoomable Chaos Game Representation images.\\nYear: 2009\\n\\nAbstract: Chaos Game Representation (CGR) is a generalized scale-independent Markov transition table, which is useful for the visualization and comparative study of genomic signature, or for the study of characteristic sequence motifs. However, in order to fully utilize the scale-independent properties of CGR, it should be accessible through scale-independent user interface instead of static images. Here we describe a web server and Perl library for generating zoomable CGR images utilizing Google Maps API, which is also easily searchable for specific motifs. The web server is freely accessible at http://www.g-language.org/wiki/cgr/, and the Perl library as well as the source code is distributed with the G-language Genome Analysis Environment under GNU General Public License.\",\n \"Title: Computational Challenges in Cell Simulation: A Software Engineering Approach\\nYear: 2002\\n\\nAbstract: The simulation of cellular processes involves diverse components and complexinteractions.To successfully model such processes, simulation systems must meet a numberofcomputational requirements, including an object-oriented design.\",\n \"Title: GPAC: Benchmarking the Sensitivity of Genome Informatics Analysis to Genome Annotation Completeness.\\nYear: 2006\\n\\nAbstract: In view of the recent explosion in genome sequence data, and the 200 or more complete genome sequences currently available, the importance of genome-scale bioinformatics analysis is increasing rapidly. However, computational genome informatics analyses often lack a statistical assessment of their sensitivity to the completeness of the functional annotation. Therefore, a pre-analysis method to automatically validate the sensitivity of computational genome analyses with regard to genome annotation completeness is useful for this purpose. In this report we developed the Gene Prediction Accuracy Classification (GPAC) test, which provides statistical evidence of sensitivity by repeating the same analysis for five different gene groups (classified according to annotation accuracy level), and for randomly sampled gene groups, with the same number of genes as each of the five classified groups. Variability in these results is then assessed, and if the results vary significantly with different data subsets, the analysis is considered \\\"sensitive\\\" to annotation completeness, and careful selection of data is advised prior to the actual in silico analysis. The GPAC test has been applied to the analyses of Sakai et al., 2001, and Ohno et al., 2001, and it revealed that the analysis of Ohno et al. was more sensitive to annotation completeness. It showed that GPAC could be employed to ascertain the sensitivity of an analysis. The GPAC bendhmarking software is freely available in the latest G-language Genome Analysis Environment package, at http://www.g-language.org/.\",\n \"Title: Janus 93: Towards Spontaneous Speech Translation\\nYear: 1994\\n\\nAbstract: Abstract: We present first results from our efforts toward translationof spontaneously spoken speech. Improvements includeincreasing coverage, robustness, generality and speedof JANUS, the speech-to-speech translation system ofCarnegie Mellon and Karlsruhe University. Recognitionand Machine Translation Engine have been upgraded todeal with requirements introduced by spontaneous humanto human dialogs. To allow for development and evaluationof our system on adequate data, a large database with...\",\n \"Title: A generalized parser for 2-D languages\\nYear: 1991\\n\\nAbstract: The authors present an extension of the Earley's (1970) generalized parser to the case of two-dimensional languages. They describe two-dimensional (positional) grammars as generalizations of context-free string grammars. The technique used to extend the Earley's algorithm is the same used for constructing a positional LR (pLR) parser. The main idea is to allow the parser to choose the next symbol to parse from a two-dimensional space\",\n \"Title: Future directions for cyber knowledge and databases\\nYear: 2004\\n\\nAbstract: In the design of multimedia database systems, one of the important issues is how to deal with \\\"Kansei\\\" of human beings. The concept of \\\"Kansei\\\" includes several meanings on sensitive recognition, such as \\\"human senses,\\\" \\\"feelings,\\\" \\\"sensitivity,\\\" \\\"psychological reaction\\\" and \\\"physiological reaction\\\" [1].In the field of database systems, the concept of Kansei is related to data definition and data retrieval with Kansei information for multimedia data, such as images, music and video. The important subject is to retrieve images and music dynamically according to the user's impression given as Kansei information. We review some multimedia systems which manipulate Kansei information for defining and retrieving multimedia data.\",\n \"Title: The Dynamics Of Cellular Energetics During Continuous Yeast Culture\\nYear: 2013\\n\\nAbstract: A plethora of data is accumulating from high throughput methods on metabolites, coenzymes, proteins, and nucleic acids and their interactions as well as the signalling and regulatory functions and pathways of the cellular network. The frozen moment viewed in a single discrete time sample requires frequent repetition and updating before any appreciation of the dynamics of component interaction becomes possible. Even then in a sample derived from a cell population, time-averaging of processes and events that occur in out-of-phase individuals blur the detailed complexity of single cell organization. Continuously-grown cultures of yeast can become spontaneously self-synchronized, thereby enabling resolution of far more detailed temporal structure. Continuous on-line monitoring by rapidly responding sensors (O-2 electrode and membrane-inlet mass spectrometry for O-2, CO2 and H2S; direct fluorimetry for NAD(P) H and flavins) gives dynamic information from time-scales of minutes to hours. Supplemented with capillary electophoresis and gas chromatography mass spectrometry and transcriptomics the predominantly oscillatory behaviour of network components becomes evident, with a 40 min cycle between a phase of increased respiration (oxidative phase) and decreased respiration (reductive phase). Highly pervasive, this ultradian clock provides a coordinating function that links mitochondrial energetics and redox balance to transcriptional regulation, mitochondrial structure and organelle remodelling, DNA duplication and cell division events. Ultimately, this leads to a global partitioning of anabolism and catabolism and the enzymes involved, mediated by a relatively simple ATP feedback loop on chromatin architecture.\",\n \"Title: A Generic Software Platform for Brain-inspired Cognitive Computing.\\nYear: 2015\\n\\nAbstract: We have been developing BriCA (Brain-inspired Computing Architecture), the generic software platform that can combine an arbitrary number of machine learning modules to construct higher structures such as cognitive architectures inspired by the brain. We discuss requirements analysis and design principles of this cognitive computing platform, report its implementation, and describe plans for further development.\",\n \"Title: BriCA: A Modular Software Platform for Whole Brain Architecture.\\nYear: 2016\\n\\nAbstract: Brain-inspired Computing Architecture (BriCA) is a generic software platform for modular composition of machine learning algorithms. It can combine and schedule an arbitrary number of machine learning components in a brain-inspired fashion to construct higher level structures such as cognitive architectures. We would like to report and discuss the core concepts of BriCA version 1 and prospects toward future development.\",\n \"Title: MICOP: Maximal information coefficient-based oscillation prediction to detect biological rhythms in proteomics data.\\nYear: 2018\\n\\nAbstract: In this paper, we presented MICOP, which is an MIC-based algorithm, for predicting periodic patterns in large-scale time-resolved protein expression profiles. The performance test using artificially generated simulation data revealed that the performance of MICOP for decaying data was superior to that of the existing widely used methods. It can reveal novel findings from time-series data and may contribute to biologically significant results. This study suggests that MICOP is an ideal approach for detecting and characterizing oscillations in time-resolved omics data sets.\",\n \"Title: An efficient context-free parsing algorithm for natural languages\\nYear: 1985\\n\\nAbstract: In this paper we present a type inference method for Prolog programs. The new idea is to describe a superset of the success set by associating a type substitution (an assignment of sets of ground terms to variables) with each head of definite clause. ...\",\n \"Title: Parameter estimation for stiff equations of biosystems using radial basis function networks.\\nYear: 2006\\n\\nAbstract: The modeling of dynamic systems requires estimating kinetic parameters from experimentally measured time-courses. Conventional global optimization methods used for parameter estimation, e.g. genetic algorithms (GA), consume enormous computational time because they require iterative numerical integrations for differential equations. When the target model is stiff, the computational time for reaching a solution increases further.In an attempt to solve this problem, we explored a learning technique that uses radial basis function networks (RBFN) to achieve a parameter estimation for biochemical models. RBFN reduce the number of numerical integrations by replacing derivatives with slopes derived from the distribution of searching points. To introduce a slight search bias, we implemented additional data selection using a GA that searches data-sparse areas at low computational cost. In addition, we adopted logarithmic transformation that smoothes the fitness surface to obtain a solution simply. We conducted numerical experiments to validate our methods and compared the results with those obtained by GA. We found that the calculation time decreased by more than 50% and the convergence rate increased from 60% to 90%.In this work, our RBFN technique was effective for parameter optimization of stiff biochemical models.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":64,"string":"64"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":275,"string":"275"}}},{"rowIdx":276,"cells":{"question_id":{"kind":"string","value":"Bonnie J Dorr"},"question":{"kind":"string","value":"Generate an abstract for the title \"Large-Scale Dictionary Construction for Foreign Language Tutoring and Interlingual Machine Translation\" using the following items: 1. Dictionaries\n2. Lexical conceptual structure\n3. Automatic construction\n4. Large-scale FLT and MT\n5. Lexicon development tools"},"answer":{"kind":"string","value":"This paper describes techniques for automatic construction of dictionaries for use in large-scale foreign language tutoring (FLT) and interlingual machine translation (MT) systems. The dictionaries are based on a language-independent representation called “lexical conceptual structure” (LCS). A primary goal of the LCS research is to demonstrate that synonymous verb senses share distributional patterns. We show how the syntax–semantics relation can be used to develop a lexical acquisition approach that contributes both toward the enrichment of existing online resources and toward the development of lexicons containing more complete information than is provided in any of these resources alone. We start by describing the structure of the LCS and showing how this representation is used in FLT and MT. We then focus on the problem of building LCS dictionaries for large-scale FLT and MT. First, we describe authoring tools for manual and semi-automatic construction of LCS dictionaries; we then present a more sophisticated approach that uses linguistic techniques for building word definitions automatically. These techniques have been implemented as part of a set of lexicon-development tools used in the milt FLT project."},"correct_answer":{"kind":"string","value":"This paper describes techniques for automatic construction of dictionaries for use in large-scale foreign language tutoring (FLT) and interlingual machine translation (MT) systems. The dictionaries are based on a language-independent representation called “lexical conceptual structure” (LCS). A primary goal of the LCS research is to demonstrate that synonymous verb senses share distributional patterns. We show how the syntax–semantics relation can be used to develop a lexical acquisition approach that contributes both toward the enrichment of existing online resources and toward the development of lexicons containing more complete information than is provided in any of these resources alone. We start by describing the structure of the LCS and showing how this representation is used in FLT and MT. We then focus on the problem of building LCS dictionaries for large-scale FLT and MT. First, we describe authoring tools for manual and semi-automatic construction of LCS dictionaries; we then present a more sophisticated approach that uses linguistic techniques for building word definitions automatically. These techniques have been implemented as part of a set of lexicon-development tools used in the milt FLT project."},"documents":{"kind":"list like","value":["Title: Computing Lexical Contrast.\nYear: 2013\n\nAbstract: Knowing the degree of semantic contrast between words has widespread application in natural language processing, including machine translation, information retrieval, and dialogue systems. Manually created lexicons focus on opposites, such as hot and cold. Opposites are of many kinds such as antipodals, complementaries, and gradable. Existing lexicons often do not classify opposites into the different kinds, however. They also do not explicitly list word pairs that are not opposites but yet have some degree of contrast in meaning, such as warm and cold or tropical and freezing. We propose an automatic method to identify contrasting word pairs that is based on the hypothesis that if a pair of words, A and B, are contrasting, then there is a pair of opposites, C and D, such that A and C are strongly related and B and D are strongly related. (For example, there exists the pair of opposites hot and cold such that tropical is related to hot, and freezing is related to cold.) We will call this the contrast hypothesis.We begin with a large crowdsourcing experiment to determine the amount of human agreement on the concept of oppositeness and its different kinds. In the process, we flesh out key features of different kinds of opposites. We then present an automatic and empirical measure of lexical contrast that relies on the contrast hypothesis, corpus statistics, and the structure of a Roget-like thesaurus. We show how, using four different data sets, we evaluated our approach on two different tasks, solving most contrasting word questions and distinguishing synonyms from opposites. The results are analyzed across four parts of speech and across five different kinds of opposites. We show that the proposed measure of lexical contrast obtains high precision and large coverage, outperforming existing methods.","Title: Interoperable query processing with multiple heterogeneous knowledge servers\nYear: 1993\n\nAbstract: This paper describes a technique for infor- mation mediation when multiple heterogeneous knowl- edge and data servers are to be accessed during query processing. One problem is building an intelligent in- terface between each knowledge server (KS) and its processor (KP); and the second is to provide interoper- ability among multiple K P/KS so that a query may be answered using information from multiple sources. We present example scenarios which highlight these prob- lems and then outline query mapping and transforma- tion techniques that are applicable. The techniques for solving the interoperability problems involve rep- resentations in some canonical form. This includes a canonical represent ation (CR) corresponding to each KP/KS pair and a merged CR (MCR) to represent the mapping among the C%. The MCR and CRa include relevant information obtained from a source query, and heterogeneous mapping (bet-map) information, for all possible mappings among the multiple servers. The knowledge in the canonical form must be represented so that it can be easily accessed during query transfor- mation. We use an example of translating queries from an object schema to a relational schema to illustrate typical knowledge that must be represented in some canonical form. We use a high level logical language, F-logic, to represent the heterogeneous mapping (het- map) and query transformation information as a set of declarative rules, in the canonical form.","Title: Leveraging reusability: cost-effective lexical acquisition for large-scale ontology translation\nYear: 2006\n\nAbstract: Thesauri and ontologies provide important value in facilitating access to digital archives by representing underlying principles of organization. Translation of such resources into multiple languages is an important component for providing multilingual access. However, the specificity of vocabulary terms in most ontologies precludes fully-automated machine translation using general-domain lexical resources. In this paper, we present an efficient process for leveraging human translations when constructing domain-specific lexical resources. We evaluate the effectiveness of this process by producing a probabilistic phrase dictionary and translating a thesaurus of 56,000 concepts used to catalogue a large archive of oral histories. Our experiments demonstrate a cost-effective technique for accurate machine translation of large ontologies.","Title: Generating targeted paraphrases for improved translation\nYear: 2013\n\nAbstract: Today's Statistical Machine Translation (SMT) systems require high-quality human translations for parameter tuning, in addition to large bitexts for learning the translation units. This parameter tuning usually involves generating translations at different points in the parameter space and obtaining feedback against human-authored reference translations as to how good the translations. This feedback then dictates what point in the parameter space should be explored next. To measure this feedback, it is generally considered wise to have multiple (usually 4) reference translations to avoid unfair penalization of translation hypotheses which could easily happen given the large number of ways in which a sentence can be translated from one language to another. However, this reliance on multiple reference translations creates a problem since they are labor intensive and expensive to obtain. Therefore, most current MT datasets only contain a single reference. This leads to the problem of reference sparsity. In our previously published research, we had proposed the first paraphrase-based solution to this problem and evaluated its effect on Chinese-English translation. In this article, we first present extended results for that solution on additional source languages. More importantly, we present a novel way to generate “targeted” paraphrases that yields substantially larger gains (up to 2.7 BLEU points) in translation quality when compared to our previous solution (up to 1.6 BLEU points). In addition, we further validate these improvements by supplementing with human preference judgments obtained via Amazon Mechanical Turk.","Title: Handling Translation Divergences: Combining Statistical and Symbolic Techniques in Generation-Heavy Machine Translation\nYear: 2002\n\nAbstract: This paper describes a novel approach to handling translation divergences in a Generation-Heavy Hybrid Machine Translation (GHMT) system. The translation divergence problem is usually reserved for Transfer and Interlingual MT because it requires a large combination of complex lexical and structural mappings. A major requirement of these approaches is the accessibility of large amounts of explicit symmetric knowledge for both source and target languages. This limitation renders Transfer and Interlingual approaches ineffective in the face of structurally-divergent language pairs with asymmetric resources. GHMT addresses the more common form of this problem, source-poor/targetrich, by fully exploiting symbolic and statistical target-language resources. This non-interlingual non-transfer approach is accomplished by using target-language lexical semantics, categorial variations and subcategorization frames to overgenerate multiple lexico-structural variations from a target-glossed syntactic dependency of the source-language sentence. The symbolic overgeneration, which accounts for different possible translation divergences, is constrained by a statistical target-language model.","Title: A maximum entropy approach to combining word alignments\nYear: 2006\n\nAbstract: This paper presents a new approach to combining outputs of existing word alignment systems. Each alignment link is represented with a set of feature functions extracted from linguistic features and input alignments. These features are used as the basis of alignment decisions made by a maximum entropy approach. The learning method has been evaluated on three language pairs, yielding significant improvements over input alignments and three heuristic combination methods. The impact of word alignment on MT quality is investigated, using a phrase-based MT system.","Title: Leveraging Recurrent Phrase Structure in Large-scale Ontology Translation\nYear: 2006\n\nAbstract: This paper presents a process for leveraging structural relationships and reusable phrases when translating large-scale ontologies. Digital libraries are becoming more and more prevalent. An important step in providing universal access to such material is to pro- vide multi-lingual access to the underlying principles of organization via ontologies, thesauri, and controlled vocabularies. Machine translation of these resources requires high accuracy and a deep vocabulary. Human input is often required, but full manual translation can be slow and expensive. We report on a cost-effective approach to ontology translation. We describe our technique of prioritization, our process of collecting aligned translations and generating a new lexicon, and the resulting improvement to translation system output. Our preliminary evaluation indicates that this technique provides significant cost savings for human-assisted translation. The process we developed can be applied to ontologies in other domains and is easily incorporated into other translation systems.","Title: DUSTer: A Method for Unraveling Cross-Language Divergences for Statistical Word-Level Alignment\nYear: 2002\n\nAbstract: The frequent occurrence of divergences--structural differences between languages--presents a great challenge for statistical word-level alignment. In this paper, we introduce DUSTer, a method for systematically identifying common divergence types and transforming an English sentence structure to bear a closer resemblance to that of another language. Our ultimate goal is to enable more accurate alignment and projection of dependency trees in another language without requiring any training on dependency-tree data in that language. We present an empirical analysis comparing the complexities of performing word-level alignments with and without divergence handling. Our results suggest that our approach facilitates word-level alignment, particularly for sentence pairs containing divergences.","Title: Cross-Language Access to Recorded Speech in the MALACH Project\nYear: 2002\n\nAbstract: The MALACH project seeks to help users find information in a vast multilingual collections of untranscribed oral history interviews. This paper introduces the goals of the project and focuses on supporting access by users who are unfamiliar with the interview language. It begins with a review of the state of the art in cross-language speech retrieval; approaches that will be investigated in the project are then described. Czech was selected as the first non-English language to be supported, so results of an initial experiment with Czech/English cross-language retrieval are reported.","Title: Interlingual machine translation: a parameterized approach\nYear: 1993\n\nAbstract: The task of designing a machine translation system is difficult because, in order to achieve any degree of accuracy, such systems must capture language-independent information while still systematically processing many types of language-specific phenomena in each of the individual languages. This paper provides a catalog of certain types of distinctions among Spanish, English, and German, and describes a parameterized interlingual approach that characterizes these distinctions, both at the syntactic level and at the lexical-semantic level. The parameter-setting approach to machine translation is desirable because it simplifies the descriptions of natural grammars, facilitates the task of modifying and augmenting the system, accounts for cross-linguistic variation uniformly, and provides a more constrained theory of processing. The approach described here is implemented in a system called UNITRAN, an interlingual machine translation system that translates English, Spanish, and German bidirectionally.","Title: Modality and negation in simt use of modality and negation in semantically-informed syntactic mt\nYear: 2012\n\nAbstract: This article describes the resource-and system-building efforts of an 8-week Johns Hopkins University Human Language Technology Center of Excellence Summer Camp for Applied Language Exploration (SCALE-2009) on Semantically Informed Machine Translation (SIMT). We describe a new modality/negation (MN) annotation scheme, the creation of a (publicly available) MN lexicon, and two automated MN taggers that we built using the annotation scheme and lexicon. Our annotation scheme isolates three components of modality and negation: a trigger (a word that conveys modality or negation), a target (an action associated with modality or negation), and a holder (an experiencer of modality). We describe how our MN lexicon was semi-automatically produced and we demonstrate that a structure-based MN tagger results in precision around 86% (depending on genre) for tagging of a standard LDC data set. We apply our MN annotation scheme to statistical machine translation using a syntactic framework that supports the inclusion of semantic annotations. Syntactic tags enriched with semantic annotations are assigned to parse trees in the target-language training texts through a process of tree grafting. Although the focus of our work is modality and negation, the tree grafting procedure is general and supports other types of semantic information. We exploit this capability by including named entities, produced by a pre-existing tagger, in addition to the MN elements produced by the taggers described here. The resulting system significantly outperformed a linguistically naive baseline model (Hiero), and reached the highest scores yet reported on the NIST 2009 Urdu-English test set. This finding supports the hypothesis that both syntactic and semantic information can improve translation quality.","Title: Exploiting aspectual features and connecting words for summarization-inspired temporal-relation extraction\nYear: 2007\n\nAbstract: This paper presents a model that incorporates contemporary theories of tense and aspect and develops a new framework for extracting temporal relations between two sentence-internal events, given their tense, aspect, and a temporal connecting word relating the two events. A linguistic constraint on event combination has been implemented to detect incorrect parser analyses and potentially apply syntactic reanalysis or semantic reinterpretation-in preparation for subsequent processing for multi-document summarization. An important contribution of this work is the extension of two different existing theoretical frameworks-Hornstein's 1990 theory of tense analysis and Allen's 1984 theory on event ordering-and the combination of both into a unified system for representing and constraining combinations of different event types (points, closed intervals, and open-ended intervals). We show that our theoretical results have been verified in a large-scale corpus analysis. The framework is designed to inform a temporally motivated sentence-ordering module in an implemented multi-document summarization system.","Title: Cross-language headline generation for Hindi\nYear: 2003\n\nAbstract: This paper presents new approaches to headline generation for English newspaper texts, with an eye toward the production of document surrogates for document selection in cross-language information retrieval. This task is difficult because the user must make decisions about relevance based on (often poor) translations of retrieved documents. To facilitate the decision-making process we need translations that can be assessed rapidly and accurately; our approach is to provide an English headline for the non-English document. We describe two approaches to headline generation and their application to the recent DARPA TIDES-2003 Surprise Language Exercise for Hindi. For comparison, we also implemented an alternative method for surrogate generation: a system that produces topic lists for (Hindi) articles. We present the results of a series of experiments comparing each of these approaches. We demonstrate in both automatic and human evaluations that our linguistically motivated approach outperforms two other surrogate-generation methods: a statistical system and a topic discovery system.","Title: Machine translation of spatial expressions: defining the relation between an interlingua and a knowledge representation system\nYear: 1993\n\nAbstract: In this paper we present one aspect of our research on machine translation (MT): defining the relation between the interlingua (IL) and a knowledge representation (KR) within an MT system. Our interest lies in the translation of natural language (NL) sentences where the \"message\" contains a spatial relation - in particular, where the sentence conveys information about the location or path of physical entities in the real, physical world. We explore several arguments for clarifying the source of constraints on the particular IL structures needed to translate these sentences. This paper develops one approach to defining these constraints and building an MT system where the IL structures designed to satisfy these constraints may be tested. In this way, we have begun to address one of the basic issues in MT research, providing independent justification for the IL itself.","Title: Lexical Selection for Cross-Language Applications: Combining LCS with WordNet\nYear: 1998\n\nAbstract: This paper describes experiments for testing the power of large-scale resources for lexical selection in machine translation (MT) and cross-language information retrieval (CLIR). We adopt the view that verbs with similar argument structure share certain meaning components, but that those meaning components are more relevant to argument realization than to idiosyncratic verb meaning. We verify this by demonstrating that verbs with similar argument structure as encoded in Lexical Conceptual Structure (LCS) are rarely synonymous in WordNet. We then use the results of this work to guide our implementation of an algorithm for cross-language selection of lexical items, exploiting the strengths of each resource: LCS for semantic structure and WordNet for semantic content. We use the Parka Knowledge-Based System to encode LCS representations and WordNet synonym sets and we implement our lexical-selection algorithm as Parka-based queries into a knowledge base containing both information types.","Title: Iterative translation disambiguation for cross-language information retrieval\nYear: 2005\n\nAbstract: Finding a proper distribution of translation probabilities is one of the most important factors impacting the effectiveness of a cross-language information retrieval system. In this paper we present a new approach that computes translation probabilities for a given query by using only a bilingual dictionary and a monolingual corpus in the target language. The algorithm combines term association measures with an iterative machine learning approach based on expectation maximization. Our approach considers only pairs of translation candidates and is therefore less sensitive to data-sparseness issues than approaches using higher n-grams. The learned translation probabilities are used as query term weights and integrated into a vector-space retrieval system. Results for English-German cross-lingual retrieval show substantial improvements over a baseline using dictionary lookup without term weighting.","Title: Enhancing Automatic Acquisition of the Thematic Structure in a Large-Scale Lexicon for Mandarin Chinese\nYear: 1998\n\nAbstract: This paper describes a refinement to our procedure for porting lexical conceptual structure (LCS) into new languages. Specifically we describe a two-step process for creating candidate thematic grids for Mandarin Chinese verbs, using the English verb heading the VP in the subdefinitions to separate senses, and roughly parsing the verb complement structure to match thematic structure templates. We accomplished a substantial reduction in manual effort, without substantive loss. The procedure is part of a larger process of creating a usable lexicon for interlingual machine translation from a large on-line resource with both too much and too little information.","Title: NeurAlign: combining word alignments using neural networks\nYear: 2005\n\nAbstract: This paper presents a novel approach to combining different word alignments. We view word alignment as a pattern classification problem, where alignment combination is treated as a classifier ensemble, and alignment links are adorned with linguistic features. A neural network model is used to learn word alignments from the individual alignment systems. We show that our alignment combination approach yields a significant 20--34% relative error reduction over the best-known alignment combination technique on English-Spanish and English-Chinese data.","Title: Alignment link projection using transformation-based learning\nYear: 2005\n\nAbstract: We present a new word-alignment approach that learns errors made by existing word alignment systems and corrects them. By adapting transformation-based learning to the problem of word alignment, we project new alignment links from already existing links, using features such as POS tags. We show that our alignment link projection approach yields a significantly lower alignment error rate than that of the best performing alignment system (22.6% relative reduction on English-Spanish data and 23.2% relative reduction on English-Chinese data).","Title: Building a Chinese-English Mapping between Verb Concepts for Multilingual Applications\nYear: 2000\n\nAbstract: This paper addresses the problem of building conceptual resources for multilingual applications. We describe new techniques for large-scale construction of a Chinese-English lexicon for verbs, using thematic-role information to create links between Chinese and English conceptual information. We then present an approach to compensating for gaps in the existing resources. The resulting lexicon is used for multilingual applications such as machine translation and cross-language information retrieval.","Title: Query transformation techniques for interoperable query processing in cooperative information systems\nYear: 1994\n\nAbstract: : This paper describes a technique to support interoperable queryprocessing, when multiple heterogeneous servers are accessed in a cooperativeinformation system (CoopIS). The problem is to support query transformationtransparently, so a user can pose queries locally, without needingglobal knowledge about different data models and schema in the CoopIS.An architecture for supporting interoperability is described and we providesome details of transforming queries from an object schema...","Title: A Survey of Current Paradigms in Machine Translation\nYear: 1999\n\nAbstract: Abstract This paper is a survey of the current machine translation research in the US, Europe and Japan. A short history of machine translation is presented first, followed by an overview of the current research work. Representative examples of a wide range of different approaches adopted by machine translation researchers are presented. These are described in detail along with a discussion of the practicalities of scaling up these approaches for operational environments. In support of this discussion, issues in, and techniques for, evaluating machine translation systems are addressed.","Title: Large-scale acquisition of LCS-based lexicons for foreign language tutoring\nYear: 1997\n\nAbstract: We focus on the problem of building large repositories of lexical conceptual structure (LCS) representations for verbs in multiple languages. One of the man results of this work is the definition of a relation between broad semantic classes and LCS meaning components. Our acquisition program---LEXICALL---takes, as input, the result of previous work on verb classification and thematic grid tagging, and outputs LCS representations for different languages. These representations have been ported into English. Arabic and Spanish lexicons, each containing approximately 9000 verbs. We are currently using these lexicons in an operational foreign language tutoring and machine translation.","Title: A cost-effective lexical acquisition process for large-scale thesaurus translation\nYear: 2009\n\nAbstract: Thesauri and controlled vocabularies facilitate access to digital collections by explicitly representing the underlying principles\n of organization. Translation of such resources into multiple languages is an important component for providing multilingual\n access. However, the specificity of vocabulary terms in most thesauri precludes fully-automatic translation using general-domain\n lexical resources. In this paper, we present an efficient process for leveraging human translations to construct domain-specific\n lexical resources. This process is illustrated on a thesaurus of 56,000 concepts used to catalog a large archive of oral histories.\n We elicited human translations on a small subset of concepts, induced a probabilistic phrase dictionary from these translations,\n and used the resulting resource to automatically translate the rest of the thesaurus. Two separate evaluations demonstrate\n the acceptability of the automatic translations and the cost-effectiveness of our approach.","Title: Are Multiple Reference Translations Necessary? Investigating the Value of Paraphrased Reference Translations in Parameter Optimization\nYear: 2008\n\nAbstract: Abstract Most state-of-the-art statistical machine trans- lation systems use log-linear models, which are defined in terms of hypothesis features and weights for those features. It is standard to tune the feature weights in order to maxi- mize a translation quality metric, using held- out test sentences and their corresponding ref- erence translations. However, obtaining refer- ence translations is expensive. In our earlier work (Madnani et al., 2007), we introduced a new full-sentence paraphrase technique, based on English-to-English decoding with an MT system, and demonstrated that the resulting paraphrases can be used to cut the number,of human,reference translations needed in half. In this paper, we take the idea a step further, asking how far it is possible to get with just a single good reference translation for each item in the development,set. Our analysis suggests that it is necessary to invest in four or more hu- man translations in order to significantly im- prove on a single translation augmented,by monolingual,paraphrases.","Title: The ACL Anthology Reference Corpus: A Reference Dataset for Bibliographic Research in Computational Linguistics\nYear: 2008\n\nAbstract: The ACL Anthology is a digital archive of conference and journal papers in natural language processing and computational linguistics. Its primary purpose is to serve as a reference repository of research results, but we believe that it can also be an object of study and a platform for research in its own right. We describe an enriched and standardized reference corpus derived from the ACL Anthology that can be used for research in scholarly document processing. This corpus, which we call the ACL Anthology Reference Corpus (ACL ARC), brings together the recent activities of a number of research groups around the world. Our goal is to make the corpus widely available, and to encourage other researchers to use it as a standard testbed for experiments in both bibliographic and bibliometric research.","Title: Generation-heavy hybrid machine translation\nYear: 2002\n\nAbstract: The state of the art techniques in Machine Translation (MT) require large amounts of symmetric resources from source and target languages. This is true regardless of whether the approach is Transfer or Interlingua, Symbolic or Statistical. Symmetry within these approaches is necessary to ensure quality, robustness and retargetability. In reality, such symmetry, whether it is in terms of structural transfer lexicons, interlingual dictionaries or parallel corpora, is a major bottleneck in developing any MT system. This dissertation presents an approach to MT that addresses the lack of symmetry by exploiting symbolic and statistical target language resources in source-poor/target-rich language pairs. This approach is called Generation-Heavy Hybrid Machine Translation (GHMT). Expected source language resources include a syntactic parser and a simple one-to-many translation dictionary. No transfer rules or complex interlingual representations are used. Rich target language symbolic resources are used to overgenerate multiple structural variations from a target-glossed syntactic dependency representation of source language sentences. Statistical target-language resource are then used to select amongst the overgenerated translations. The source-target asymmetry of systems developed in this approach makes them more easily retargetable to new source languages. The contributions of this research include: (1) a new model for machine translation that transcends the need for large amounts of symmetric knowledge while maintaining a high degree of robustness, quality, and retargetability; (2) a systematic framework for handling translation divergences that uniformly accommodates a wide range of seemingly different divergence types and their interactions; (3) a hybrid (symbolic-statistical) generation approach that expands the concept of symbolic overgeneration to include conflation and head-swapping of structural variations; (4) the introduction and use of structural n-grams on a large scale in natural language generation; and (5) the creation of several resources that have been used by other researchers including an extensible MT system for translating into English and a large-scale categorical variation database for English. An extensive evaluation suggests that GHMT is more robust and has superior output quality, in terms of grammaticality and accuracy, relative to a primarily statistical approach.","Title: Language and translation model adaptation using comparable corpora\nYear: 2008\n\nAbstract: Traditionally, statistical machine translation systems have relied on parallel bi-lingual data to train a translation model. While bi-lingual parallel data are expensive to generate, monolingual data are relatively common. Yet monolingual data have been under-utilized, having been used primarily for training a language model in the target language. This paper describes a novel method for utilizing monolingual target data to improve the performance of a statistical machine translation system on news stories. The method exploits the existence of comparable text---multiple texts in the target language that discuss the same or similar stories as found in the source language document. For every source document that is to be translated, a large monolingual data set in the target language is searched for documents that might be comparable to the source documents. These documents are then used to adapt the MT system to increase the probability of generating texts that resemble the comparable document. Experimental results obtained by adapting both the language and translation models show substantial gains over the baseline system.","Title: Interlingual Annotation for MT Development\nYear: 2004\n\nAbstract: MT systems that use only superficial representations, including the current generation of statistical MT systems, have been successful and useful. However, they will experience a plateau in quality, much like other \"silver bullet\" approaches to MT. We pursue work on the development of interlingual representations for use in symbolic or hybrid MT systems. In this paper, we describe the creation of an interlingua and the development of a corpus of semantically annotated text, to be validated in six languages and evaluated in several ways. We have established a distributed, well-functioning research methodology, designed a preliminary interlingua notation, created annotation manuals and tools, developed a test collection in six languages with associated English translations, annotated some 150 translations, and designed and applied various annotation metrics. We describe the data sets being annotated and the interlingual (IL) representation language which uses two ontologies and a systematic theta-role list. We present the annotation tools built and outline the annotation process. Following this, we describe our evaluation methodology and conclude with a summary of issues that have arisen.","Title: Selecting tense aspect and connecting words in language generation\nYear: 1995\n\nAbstract: Generating language that reflects the temporal organization of represented knowledge requires a language generation model chat integrates contemporary theories of tense and aspect, temporal representations, and methods to plan text This paper presents a model that produces complex sentences that reflect temporal relations present in underlying temporal concepts The mam result of this work is the successful application of constrained linguistic theories of tense and aspect to a generator which produces meaningful event combinations and selects appropriate connecting words that relate them.","Title: Single-document and multi-document summarization techniques for email threads using sentence compression\nYear: 2008\n\nAbstract: We present two approaches to email thread summarization: collective message summarization (CMS) applies a multi-document summarization approach, while individual message summarization (IMS) treats the problem as a sequence of single-document summarization tasks. Both approaches are implemented in our general framework driven by sentence compression. Instead of a purely extractive approach, we employ linguistic and statistical methods to generate multiple compressions, and then select from those candidates to produce a final summary. We demonstrate these ideas on the Enron email collection - a very challenging corpus because of the highly technical language. Experimental results point to two findings: that CMS represents a better approach to email thread summarization, and that current sentence compression techniques do not improve summarization performance in this genre.","Title: Multi-align: Combining Linguistic and Statistical Techniques to Improve Alignments for Adaptable MT\nYear: 2004\n\nAbstract: An adaptable statistical or hybrid TAT system relies heavily on the quality of word-level alignments of real-world data. Statistical alignment approaches provide a reasonable initial estimate for word alignment. However, they cannot handle certain types of linguistic phenomena such as long-distance dependencies and structural differences between languages. We address this issue in Multi-Align, a new framework for incremental testing of different alignment algorithms and their combinations. Our design allows users to tune their systems to the properties of a particular genre/domain while still benefiting from general linguistic knowledge associated with a language pair. We demonstrate that a combination of statistical and linguistically-informed alignments can resolve translation divergences during the alignment process.","Title: Multilingual generation: The role of telicity in lexical choice and syntactic realization\nYear: 1996\n\nAbstract: . Multilingual generation in machine translation (MT) requires a knowledgeorganization that facilitates the task of lexical choice, i.e., selection of lexicalunits to be used in the generation of a target-language sentence. This paper investigatesthe extent to which lexicalization patterns involving the lexical aspect feature[+telic] (`having an inherent end\" as in win vs. run) may be used for translatingevents and states among languages. The work reported here is part of an ongoingeffort ...","Title: A parameterized approach to integrating aspect with lexical-semantics for machine translation\nYear: 1992\n\nAbstract: This paper discusses how a two-level knowledge rep- resentation model for machine translation integrates as- pectual information with lexical-semantic information by means of parameterization. The integration of aspect with lexical-semantics is especially critical in machine translation because of the lexical selection and aspec- tual realization processes that operate during the pro- duction of the target-language sentence: there are of- ten a large number of lexical and aspectual possibili- ties to choose from in the production of a sentence from a lexical semantic representation. Aspectual informa- tion from the source-language sentence constrains the choice of target-language terms. In turn, the target- language terms limit the possibilities for generation of aspect. Thus, there is a two-way communication chan- nel between the two processes. This paper will show that the selection/realization processes may be parame- terized so that they operate uniformly across more than one language and it will describe how the parameter- based approach is currently being used as the basis for extraction of aspectual information from corpora.","Title: Mapping lexical entries in a verbs database to WordNet senses\nYear: 2001\n\nAbstract: This paper describes automatic techniques for mapping 9611 entries in a database of English verbs to WordNet senses. The verbs were initially grouped into 491 classes based on syntactic features. Mapping these verbs into WordNet senses provides a resource that supports disambiguation in multilingual applications such as machine translation and cross-language information retrieval. Our techniques make use of (1) a training set of 1791 disambiguated entries, representing 1442 verb entries from 167 classes; (2) word sense probabilities, from frequency counts in a tagged corpus; (3) semantic similarity of WordNet senses for verbs within the same class; (4) probabilistic correlations between WordNet data and attributes of the verb classes. The best results achieved 72% precision and 58% recall, versus a lower bound of 62% precision and 38% recall for assigning the most frequently occurring WordNet sense, and an upper bound of 87% precision and 75% recall for human judgment.","Title: Machine translation divergences: a formal description and proposed solution\nYear: 1994\n\nAbstract: There are many cases in which the natural translation of one language into another results in a very different form than that of the original. The existence of translation divergences (i.e., crosslinguistic distinctions) makes the straightforward transfer from source structures into target structures impractical. Many existing translation systems have mechanisms for handling divergent structures but do not provide a general procedure that takes advantage of takes advantage of the systematic relation between lexical-semantic structure and syntactic structure. This paper demonstrates that a systematic solution to the divergence problem can be derived from the formalization of two types of information: (1) the linguistically grounded classes upon which lexical-semantic divergences are based; and (2) the techniques by which lexical-semantic divergences are resolved. This formalization is advantageous in that it facilitates the design and implementation of the system, allows one to make an evaluation of the status of the system, and provides a basis for proving certain important properties about the system.","Title: Chinese-English Semantic Resource Construction\nYear: 2000\n\nAbstract: We describe an approach to large-scale construction of a semantic lexicon for Chinese verbs. We leverage off of three existing resources— a classification of English verbs called EVCA (English Verbs Classes and Alternations) (Levin, 1993), a Chinese conceptual database called HowNet (Zhendong, 1988c; Zhendong, 1988b; Zhendong, 1988a) (http://www .how-net.com), and a large machine-readable dic- tionary called Optilex. The resulting lexicon is used for determining appropriate word senses in applications such as machine translation and cross-language information retrieval.","Title: Rapid porting of DUSTer to Hindi\nYear: 2003\n\nAbstract: The frequent occurrence of divergences—structural differences between languages---presents a great challenge for statistical word-level alignment and machine translation. This paper describes the adaptation of DUSTer, a divergence unraveling package, to Hindi during the DARPA TIDES-2003 Surprise Language Exercise. We show that it is possible to port DUSTer to Hindi in under 3 days.","Title: Efficient parsing for Korean and English: a parameterized message-passing approach\nYear: 1995\n\nAbstract: This article presents an efficient, implemented approach to cross-linguistic parsing basedon Government-Binding (GB) Theory (Chomsky, 1986) and followers. One of the drawbacksto alternative GB-based parsing approaches is that they generally adopt a filterbasedparadigm. These approaches typically generate all possible candidate structuresof the sentence that satisfy X theory, and then subsequently apply filters in order toeliminate those structures that violate GB principles. (See, for...","Title: Reranking for Sentence Boundary Detection in Conversational Speech\nYear: 2006\n\nAbstract: We present a reranking approach to sentence-like unit (SU) boundary detection, one of the EARS metadata extraction tasks. Techniques for generating relatively small n-best lists with high oracle accuracy are presented. For each candidate, features are derived from a range of information sources, including the output of a number of parsers. Our approach yields significant improvements over the best performing system from the NIST RT-04F community evaluation","Title: A Methodology for Extrinsic Evaluation of Text Summarization: Does ROUGE Correlate?\nYear: 2005\n\nAbstract: This paper demonstrates the usefulness of sum- maries in an extrinsic task of relevance judgment based on a new method for measuring agree- ment, Relevance-Prediction, which compares sub- jects' judgments on summaries with their own judg- ments on full text documents. We demonstrate that, because this measure is more reliable than previ- ous gold-standard measures, we are able to make stronger statistical statements about the benefits of summarization. We found positive correlations be- tween ROUGE scores and two different summary types, where only weak or negative correlations were found using other agreement measures. How- ever, we show that ROUGE may be sensitive to the choice of summarization style. We discuss the im- portance of these results and the implications for fu- ture summarization evaluations.","Title: The use of lexical semantics in interlingual machine translation\nYear: 1992\n\nAbstract: This paper describes the lexical-semantic basis for UNITRAN, an implemented scheme for translating Spanish, English, and German bidirectionally. Two claims made here are that the current representation handles many distinctions (or divergences) across languages without recourse to language-specific rules and that the lexical-semantic framework provides the basis for a systematic mapping between the interlingua and the syntactic structure. The representation adopted is an extended version of lexical conceptual structure which is suitable to the task of translating between divergent structures for two reasons: (1) it provides an abstraction of language-independent properties from structural idiosyncrasies; and (2) it is compositional in nature. The lexical-semantic approach addresses the divergence problem by using a linguistically grounded mapping that has access to parameter settings in the lexicon. We will examine a number of relevant issues including the problem of defining primitives, the issue of interlinguality, the cross-linguistic coverage of the system, and the mapping between the syntactic structure and the interlingua. A detailed example of lexical-semantic composition will be presented.","Title: Task-based evaluation of text summarization using Relevance Prediction\nYear: 2007\n\nAbstract: This article introduces a new task-based evaluation measure called Relevance Prediction that is a more intuitive measure of an individual's performance on a real-world task than interannotator agreement. Relevance Prediction parallels what a user does in the real world task of browsing a set of documents using standard search tools, i.e., the user judges relevance based on a short summary and then that same user-not an independent user-decides whether to open (and judge) the corresponding document. This measure is shown to be a more reliable measure of task performance than LDC Agreement, a current gold-standard based measure used in the summarization evaluation community. Our goal is to provide a stable framework within which developers of new automatic measures may make stronger statistical statements about the effectiveness of their measures in predicting summary usefulness. We demonstrate-as a proof-of-concept methodology for automatic metric developers-that a current automatic evaluation measure has a better correlation with Relevance Prediction than with LDC Agreement and that the significance level for detected differences is higher for the former than for the latter.","Title: Evaluating Resources for Query Translation in Cross-Language Information Retrieval\nYear: 1998\n\nAbstract: Our goal is to evaluate the utility of a lexical resource containing Lexical Conceptual Structures (LCS) for use in cross-language information retrieval. Our evaluation makes use of a combination of techniques from interlingual machine translation (Dorr, 1993) with conventional information retrieval techniques (Oard, 1996; Oard and Dorr, 1996). Given a query in one language, we transform the query into the corresponding terms in a second language. We evaluate this approach by comparing the...","Title: Toward a lexicalized grammar for interlinguas\nYear: 1995\n\nAbstract: . In this paper we present one aspect of our research on machine translation (MT):capturing the grammatical and computational relation between (i) the interlingua (IL) as defineddeclaratively in the lexicon and (ii) the IL as defined procedurally by way of algorithms thatcompose and decompose pivot IL forms. We begin by examining the interlinguas in the lexicons ofa variety of current IL-based approaches to MT. This brief survey makes it clear that no consensusexists among MT researchers...","Title: A Two-Level Knowledge Representation for Machine Translation: Lexical Semantics and Tense/Aspect\nYear: 1991\n\nAbstract: Abstract This paper proposes a two-level model that integrates tense and aspect information, based on theories by both Hornstein (in the spirit of Reichenbach) and Allen, with lexicai-semantic information based on an extended,version of $ackendoff's theory that includes a verb classification system,proposed,by Dowty and Vendler. The model is intended to be extensible to realms outside of the temporal domain (e.g., the spatial domain). The integration of tense and aspect with lexical-semantics is especially critical in machine,translation because of the lexical selection process during generation: there is often a number,of lexical connective and tense/aspect possibilities that may be produced from a lexical semantic representation, which, as defined in the model presented here, is largely underspecified. The use of tense and aspect information allows the choice of target-language terms to be more finely tuned and the combination,of event structures to be more carefully constrained.","Title: A Thematic Hierarchy for Efficient Generation from Lexical-Conceptual Structure\nYear: 1998\n\nAbstract: This paper describes an implemented algorithm for syntactic realization of a target-language sentence from an interlingual representation called Lexical Conceptual Structure (LCS). We provide a mapping between LCS thematic roles and Abstract Meaning Representation (AMR) relations; these relations serve as input to an off-the-shelf generator (Nitrogen). There are two contributions of this work: (1) the development of a thematic hierarchy that provides ordering information for realization of arguments in their surface positions; (2) the provision of a diagnostic tool for detecting inconsistencies in an existing online LCS-based lexicon that allows us to enhance principles for thematic-role assignment.","Title: Role of word sense disambiguation in lexical acquisition: predicting semantics from syntactic cues\nYear: 1996\n\nAbstract: This paper addresses the issue of word-sense ambiguity in extraction from machine-readable resources for the construction of large-scale knowledge sources. We describe two experiments: one which ignored word-sense distinctions, resulting in 6.3% accuracy for semantic classification of verbs based on (Levin, 1993); and one which exploited word-sense distinctions, resulting in 97.9% accuracy. These experiments were dual purpose: (1) to validate the central thesis of the work of (Levin, 1993), i.e., that verb semantics and syntactic behavior are predictably related; (2) to demonstrate that a 15-fold improvement can be achieved in deriving semantic information from syntactic cues if we first divide the syntactic cues into distinct groupings that correlate with different word senses. Finally, we show that we can provide effective acquisition techniques for novel word senses using a combination of online sources.","Title: Generating phrasal and sentential paraphrases: A survey of data-driven methods\nYear: 2010\n\nAbstract: The task of paraphrasing is inherently familiar to speakers of all languages. Moreover, the task of automatically generating or extracting semantic equivalences for the various units of language-words, phrases, and sentences-is an important part of natural language processing (NLP) and is being increasingly employed to improve the performance of several NLP applications. In this article, we attempt to conduct a comprehensive and application-independent survey of data-driven phrasal and sentential paraphrase generation methods, while also conveying an appreciation for the importance and potential use of paraphrases in the field of NLP research. Recent work done in manual and automatic construction of paraphrase corpora is also examined. We also discuss the strategies used for evaluating paraphrase generation techniques and briefly explore some future trends in paraphrase generation.","Title: Putting the user in the loop: interactive Maximal Marginal Relevance for query-focused summarization\nYear: 2010\n\nAbstract: This work represents an initial attempt to move beyond \"single-shot\" summarization to interactive summarization. We present an extension to the classic Maximal Marginal Relevance (MMR) algorithm that places a user \"in the loop\" to assist in candidate selection. Experiments in the complex interactive Question Answering (ciQA) task at TREC 2007 show that interactively-constructed responses are significantly higher in quality than automatically-generated ones. This novel algorithm provides a starting point for future work on interactive summarization.","Title: Fluency, adequacy, or HTER?: exploring different human judgments with a tunable MT metric\nYear: 2009\n\nAbstract: Automatic Machine Translation (MT) evaluation metrics have traditionally been evaluated by the correlation of the scores they assign to MT output with human judgments of translation performance. Different types of human judgments, such as Fluency, Adequacy, and HTER, measure varying aspects of MT performance that can be captured by automatic MT metrics. We explore these differences through the use of a new tunable MT metric: TER-Plus, which extends the Translation Edit Rate evaluation metric with tunable parameters and the incorporation of morphology, synonymy and paraphrases. TER-Plus was shown to be one of the top metrics in NIST's Metrics MATR 2008 Challenge, having the highest average rank in terms of Pearson and Spearman correlation. Optimizing TER-Plus to different types of human judgments yields significantly improved correlations and meaningful changes in the weight of different types of edits, demonstrating significant differences between the types of human judgments.","Title: A first-pass approach for evaluating machine translation systems\nYear: 1993\n\nAbstract: This paper describes a short-term survey and evaluationproject that covered a large number of machine translation productsand research. We discuss our evaluation approach and addresscertain issues and implications relevant to our findings.We represented a variety of potential users of MT systems andwere faced with the task of identifying which systems would besthelp them solve their translation problems.1 IntroductionDuring 1991, The MITRE Corp.1surveyed and evaluated machine...","Title: Measuring variability in sentence ordering for news summarization\nYear: 2007\n\nAbstract: The issue of sentence ordering is an important one for natural language tasks such as multi-document summarization, yet there has not been a quantitative exploration of the range of acceptable sentence orderings for short texts. We present results of a sentence reordering experiment with three experimental conditions. Our findings indicate a very high degree of variability in the orderings that the eighteen subjects produce. In addition, the variability of reorderings is significantly greater when the initial ordering seen by subjects is different from the original summary. We conclude that evaluation of sentence ordering should use multiple reference orderings. Our evaluation presents several metrics that might prove useful in assessing against multiple references. We conclude with a deeper set of questions: (a) what sorts of independent assessments of quality of the different reference orderings could be made and (b) whether a large enough test set would obviate the need for such independent means of quality assessment.","Title: Interpretation of Compound Nominals Using WordNet\nYear: 2001\n\nAbstract: We describe an approach to interpreting noun-noun compounds within a question answering system. The system's lexicon, based on WordNet, provides the basis for heuristics that group noun-noun compounds with semantically similar words. The semantic relationship between the nouns in a compound is determined by the choice of heuristic for the compound. We discuss procedures for selecting one heuristic in cases where several can apply to a compound, the effects of lexical ambiguity, and some initial results of our methods.","Title: Going beyond AER: an extensive analysis of word alignments and their impact on MT\nYear: 2006\n\nAbstract: This paper presents an extensive evaluation of five different alignments and investigates their impact on the corresponding MT system output. We introduce new measures for intrinsic evaluations and examine the distribution of phrases and untranslated words during decoding to identify which characteristics of different alignments affect translation. We show that precision-oriented alignments yield better MT output (translating more words and using longer phrases) than recall-oriented alignments.","Title: Multi-candidate reduction: Sentence compression as a tool for document summarization tasks\nYear: 2007\n\nAbstract: This article examines the application of two single-document sentence compression techniques to the problem of multi-document summarization-a ''parse-and-trim'' approach and a statistical noisy-channel approach. We introduce the multi-candidate reduction (MCR) framework for multi-document summarization, in which many compressed candidates are generated for each source sentence. These candidates are then selected for inclusion in the final summary based on a combination of static and dynamic features. Evaluations demonstrate that sentence compression is a valuable component of a larger multi-document summarization framework.","Title: Generating extractive summaries of scientific paradigms\nYear: 2013\n\nAbstract: Researchers and scientists increasingly find themselves in the position of having to quickly understand large amounts of technical material. Our goal is to effectively serve this need by using bibliometric text mining and summarization techniques to generate summaries of scientific literature. We show how we can use citations to produce automatically generated, readily consumable, technical extractive summaries. We first propose C-LexRank, a model for summarizing single scientific articles based on citations, which employs community detection and extracts salient information-rich sentences. Next, we further extend our experiments to summarize a set of papers, which cover the same scienti fic topic. We generate extractive summaries of a set of Question Answering (QA) and Dependency Parsing (DP) papers, their abstracts, and their citation sentences and show that citations have unique information amenable to creating a summary.","Title: Combining Outputs from Multiple Machine Translation Systems\nYear: 2007\n\nAbstract: Currently there are several approaches to machine translation (MT) based on differ- ent paradigms; e.g., phrasal, hierarchical and syntax-based. These three approaches yield similar translation accuracy despite using fairly different levels of linguistic knowledge. The availability of such a variety of systems has led to a growing interest toward finding better translations by combining outputs from multiple sys- tems. This paper describes three differ- ent approaches to MT system combina- tion. These combination methods oper- ate on sentence, phrase and word level exploiting information from -best lists, system scores and target-to-source phrase alignments. The word-level combination provides the most robust gains but the best results on the development test sets (NIST MT05 and the newsgroup portion of GALE 2006 dry-run) were achieved by combining all three methods.","Title: Deriving verbal and compositional lexical aspect for NLP applications\nYear: 1997\n\nAbstract: Verbal and compositional lexical aspect provide the underlying temporal structure of events. Knowledge of lexical aspect, e.g., (a)telicity, is therefore required for interpreting event sequences in discourse (Dowty, 1986; Moens and Steedman, 1988; Passoneau, 1988), interfacing to temporal databases (Androutsopoulos, 1996), processing temporal modifiers (Antonisse, 1994), describing allowable alternations and their semantic effects (Resnik, 1996; Tenny, 1994), and selecting tense and lexical items for natural language generation ((Dorr and Olsen, 1996; Klavans and Chodorow, 1992), cf. (Slobin and Bocaz, 1988)). We show that it is possible to represent lexical aspect---both verbal and compositional---on a large scale, using Lexical Conceptual Structure (LCS) representations of verbs in the classes cataloged by Levin (1993). We show how proper consideration of these universal pieces of verb meaning may be used to refine lexical representations and derive a range of meanings from combinations of LCS representations. A single algorithm may therefore be used to determine lexical aspect classes and features at both verbal and sentence levels. Finally, we illustrate how knowledge of lexical aspect facilitates the interpretation of events in NLP applications.","Title: Using paraphrases for parameter tuning in statistical machine translation\nYear: 2007\n\nAbstract: Most state-of-the-art statistical machine translation systems use log-linear models, which are defined in terms of hypothesis features and weights for those features. It is standard to tune the feature weights in order to maximize a translation quality metric, using held-out test sentences and their corresponding reference translations. However, obtaining reference translations is expensive. In this paper, we introduce a new full-sentence paraphrase technique, based on English-to-English decoding with an MT system, and we demonstrate that the resulting paraphrases can be used to drastically reduce the number of human reference translations needed for parameter tuning, without a significant decrease in translation quality.","Title: Inducing frame semantic verb classes from WordNet and LDOCE\nYear: 2004\n\nAbstract: This paper presents SemFrame, a system that induces frame semantic verb classes from WordNet and LDOCE. Semantic frames are thought to have significant potential in resolving the paraphrase problem challenging many language-based applications.When compared to the handcrafted FrameNet, SemFrame achieves its best recall-precision balance with 83.2% recall (based on SemFrame's coverage of FrameNet frames) and 73.8% precision (based on SemFrame verbs' semantic relatedness to frame-evoking verbs). The next best performing semantic verb classes achieve 56.9% recall and 55.0% precision.","Title: A Modality Lexicon and its use in Automatic Tagging\nYear: 2010\n\nAbstract: This paper describes our resource-building results for an eight-week JHU Human Language Technology Center of Excellence Summer Camp for Applied Language Exploration (SCALE-2009) on Semantically-Informed Machine Translation. Specifically, we describe the construction of a modality annotation scheme, a modality lexicon, and two automated modality taggers that were built using the lexicon and annotation scheme. Our annotation scheme is based on identifying three components of modality: a trigger, a target and a holder. We describe how our modality lexicon was produced semi-automatically, expanding from an initial hand-selected list of modality trigger words and phrases. The resulting expanded modality lexicon is being made publicly available. We demonstrate that one tagger-a structure-based tagger-results in precision around 86% (depending on genre) for tagging of a standard LDC data set. In a machine translation application, using the structure-based tagger to annotate English modalities on an English-Urdu training corpus improved the translation quality score for Urdu by 0.3 Bleu points in the face of sparse training data.","Title: Acquisition of bilingual MT lexicons from OCRed dictionaries.\nYear: 2003\n\nAbstract: This paper describes an approach to analyzing the lexical structure of OCRed bilingual dictionaries to construct re- sources suited for machine translation of low-density languages, where online resources are limited. A rule-based, an HMM-based, and a post-processed HMM-based method are used for rapid construction of MT lexicons based on sys- tematic structural clues provided in the original dictionary. We evaluate the effectiveness of our techniques, concluding that: (1) the rule-based method performs better with dictionaries where the font is not an important distinguishing fea- ture for determining information types; (2) the post-processed stochastic method improves the results of the stochastic method for phrasal entries; and (3) Our resulting bilingual lexicons are comprehensive enough to provide the basis for reasonable translation results when compared to human translations.","Title: Solving thematic divergences in machine translation\nYear: 1990\n\nAbstract: Though most translation systems have some mechanism for translating certain types of divergent predicate-argument structures, they do not provide a general procedure that takes advantage of the relationship between lexical-semantic structure and syntactic structure. A divergent predicate-argument structure is one in which the predicate (e.g., the main verb) or its arguments (e.g., the subject and object) do not have the same syntactic ordering properties for both the source and target language. To account for such ordering differences, a machine translator must consider language-specific syntactic idiosyncrasies that distinguish a target language from a source language, while making use of lexical-semantic uniformities that tie the two languages together. This paper describes the mechanisms used by the UNITRAN machine translation system for mapping an underlying lexical-conceptual structure to a syntactic structure (and vice versa), and it shows how these mechanisms coupled with a set of general linking routines solve the problem of thematic divergence in machine translation.","Title: Semantically-Informed Syntactic Machine Translation: A Tree-Grafting Approach.\nYear: 2014\n\nAbstract: We describe a unified and coherent syntactic framework for supporting a semantically-informed syntactic approach to statistical machine translation. Semantically enriched syntactic tags assigned to the target-language training texts improved translation quality. The resulting system significantly outperformed a linguistically naive baseline model (Hiero), and reached the highest scores yet reported on the NIST 2009 Urdu-English translation task. This finding supports the hypothesis (posed by many researchers in the MT community, e.g., in DARPA GALE) that both syntactic and semantic information are critical for improving translation quality---and further demonstrates that large gains can be achieved for low-resource languages with different word order than English.","Title: Use of Modality and Negation in Semantically-Informed Syntactic MT.\nYear: 2015\n\nAbstract: This paper describes the resource- and system-building efforts of an eight-week Johns Hopkins University Human Language Technology Center of Excellence Summer Camp for Applied Language Exploration (SCALE-2009) on Semantically-Informed Machine Translation (SIMT). We describe a new modality/negation (MN) annotation scheme, the creation of a (publicly available) MN lexicon, and two automated MN taggers that we built using the annotation scheme and lexicon. Our annotation scheme isolates three components of modality and negation: a trigger (a word that conveys modality or negation), a target (an action associated with modality or negation) and a holder (an experiencer of modality). We describe how our MN lexicon was semi-automatically produced and we demonstrate that a structure-based MN tagger results in precision around 86% (depending on genre) for tagging of a standard LDC data set. We apply our MN annotation scheme to statistical machine translation using a syntactic framework that supports the inclusion of semantic annotations. Syntactic tags enriched with semantic annotations are assigned to parse trees in the target-language training texts through a process of tree grafting. While the focus of our work is modality and negation, the tree grafting procedure is general and supports other types of semantic information. We exploit this capability by including named entities, produced by a pre-existing tagger, in addition to the MN elements produced by the taggers described in this paper. The resulting system significantly outperformed a linguistically naive baseline model (Hiero), and reached the highest scores yet reported on the NIST 2009 Urdu-English test set. This finding supports the hypothesis that both syntactic and semantic information can improve translation quality.","Title: Speech Adaptation In Extended Ambient Intelligence Environments\nYear: 2015\n\nAbstract: This Blue Sky presentation focuses on a major shift toward a notion of \"ambient intelligence\" that transcends general applications targeted at the general population. The focus is on highly personalized agents that accommodate individual differences and changes over time. This notion of Extended Ambient Intelligence (EAI) concerns adaptation to a person's preferences and experiences, as well as changing capabilities, most notably in an environment where conversational engagement is central. An important step in moving this research forward is the accommodation of different degrees of cognitive capability (including speech processing) that may vary over time for a given user whether through improvement or through deterioration. We suggest that the application of divergence detection to speech patterns may enable adaptation to a speaker's increasing or decreasing level of speech impairment over time. Taking an adaptive approach toward technology development in this arena may be a first step toward empowering those with special needs so that they may live with a high quality of life. It also represents an important step toward a notion of ambient intelligence that is personalized beyond what can be achieved by mass-produced, one-size-fits-all software currently in use on mobile devices.","Title: The NIST data science evaluation series: Part of the NIST information access division data science initiative\nYear: 2015\n\nAbstract: The Information Access Division (IAD) of the National Institute of Standards and Technology (NIST) launched a new Data Science Initiative in the fall of 2015. This initiative focuses on evaluation-driven research and will establish a new Data Science Evaluation series to facilitate research collaboration, to leverage shared technology and infrastructure, and to further build and strengthen the data science community. The evaluation series will consist of a pre-pilot to be launched in the fall of 2015, a pilot evaluation to be launched in 2016, and a full-scale multiple-track evaluation in 2017. In addition to these evaluations, this new initiative aims to address several infrastructure challenges and to provide standards to encourage easier group collaboration.","Title: Multiple Alternative Sentence Compressions and Word-Pair Antonymy for Automatic Text Summarization and Recognizing Textual Entailment\nYear: 2008\n\nAbstract: Abstract The University of Maryland participated in three tasks organized by the Text Anal- ysis Conference 2008 (TAC 2008): (1) the update task of text summarization; (2) the opinion task of text summarization; and (3) recognizing textual entailment (RTE). At the heart of our summarization,sys- tem is Trimmer, which generates multi- ple alternative compressed,versions of the source sentences that act as candidate sen- tences for inclusion in the summary.,For the first time, we investigated the use of automatically generated antonym,pairs for both text summarization,and recognizing textual entailment. The UMD summaries for the opinion task were especially effec- tive in providing non-redundant informa- tion (rank 3 out of a total 19 submissions). More coherent summaries,resulted when using the antonymy,feature as compared to when not using it. On the RTE task, even when,using only automatically gen- erated antonyms,the system performed,as well as when,using a manually compiled list of antonyms.","Title: Event Nugget Detection and Argument Extraction with DISCERN.\nYear: 2016\n\nAbstract: This paper addresses the problem of detecting information about events from unstructured text. An event-detection system, DISCERN, is presented; its three variants DISCERN- R (rule-based), DISCERN-ML (machine-learned), and DISCERN-C (combined), were evaluated in the NIST TAC KBP 2015 Event Nugget Detection and Event Argument Extraction and Linking tasks. Three contributions of this work are: (a) an approach to collapsing support verb and event nominals that improved recall of argument linking, (b) a new linguist-in-the-loop paradigm that enables quick changes to linguistic rules and examination of their effect on pre- cision and recall at runtime, (c) an analysis of the synergy between the semantic and syntactic features. Results of experimentation with event-detection approaches indicate that linguistically-informed rules can improve precision and machine-learned systems can improve recall. Future refinements to the combination of linguistic and machine learning approaches may involve making better use of the complementarity of these approaches.","Title: The NIST data science initiative\nYear: 2015\n\nAbstract: We examine foundational issues in data science including current challenges, basic research questions, and expected advances, as the basis for a new Data Science Initiative and evaluation series, introduced by the National Institute of Standards and Technology (NIST) in the fall of 2015. The evaluations will facilitate research efforts, collaboration, leverage shared infrastructure, and effectively address cross-cutting challenges faced by diverse data science communities. The evaluations will have multiple research tracks championed by members of the data science community, and will enable rigorous comparison of approaches through common tasks, datasets, metrics, and shared research challenges. The tracks will measure several different data science technologies in a wide range of fields, starting with a pre-pilot. In addition to developing data science evaluation methods and metrics, it will address computing infrastructure, standards for an interoperability framework, and domain-specific examples.","Title: Deterioration of Speech as an Indicator of Physiological Degeneration (DESIPHER).\nYear: 2015\n\nAbstract: We approach the problem of understanding the disease progression and speech of patients suffering from ALS as a language divergence identification problem. We summarize the promises and challenges of using speech-related biomarkers to adapt speech recognition to ALS patients and correlate language divergence with disease progression.","Title: A new data science research program: evaluation, metrology, standards, and community outreach.\nYear: 2016\n\nAbstract: This article examines foundational issues in data science including current challenges, basic research questions, and expected advances, as the basis for a new data science research program (DSRP) and associated data science evaluation (DSE) series, introduced by the National Institute of Standards and Technology (NIST) in the fall of 2015. The DSRP is designed to facilitate and accelerate research progress in the field of data science and consists of four components: evaluation and metrology, standards, compute infrastructure, and community outreach. A key part of the evaluation and measurement component is the DSE. The DSE series aims to address logistical and evaluation design challenges while providing rigorous measurement methods and an emphasis on generalizability rather than domain- and application-specific approaches. Toward that end, each year the DSE will consist of multiple research tracks and will encourage the application of tasks that span these tracks. The evaluations are intended to facilitate research efforts and collaboration, leverage shared infrastructure, and effectively address crosscutting challenges faced by diverse data science communities. Multiple research tracks will be championed by members of the data science community with the goal of enabling rigorous comparison of approaches through common tasks, datasets, metrics, and shared research challenges. The tracks will permit us to measure several different data science technologies in a wide range of fields and will address computing infrastructure, standards for an interoperability framework, and domain-specific examples. This article also summarizes lessons learned from the data science evaluation series pre-pilot that was held in fall of 2015.","Title: Ambient Personal Environment Experiment (APEX): A Cyber-Human Prosthesis for Mental, Physical and Age-Related Disabilities.\nYear: 2015\n\nAbstract: We present an emerging research project in our laboratory to extend ambient intelligence (AmI) by what we refer to as “extreme personalization” meaning that an instance of ambient intelligence is focused on one or at most a few individuals over a very long period of time. Over a lifetime of co-activity, it senses and adapts to a person’s preferences and experiences, and crucially, his or her (changing) special needs; needs that differ significantly from the normal baseline. We refer to our agent-based cyber-physical system as Ambient Personal Environment eXperiment (APEX). It aims to serve as a Companion , a Coach , and a Caregiver : crucial support for individuals with mental, physical, and age-related disabilities and those other people who help them. We propose that an instance of APEX, interacting socially with each of these people, is both a social actor as well as a cyber-human prosthetic device . APEX is an ambitious integration of multiple technologies from Artificial Intelligence (AI) and other disciplines. Its successful development can be viewed as a grand challenge for AI. We discuss in this paper three research thrusts that lead toward our vision: robust intelligent agents, semantically rich human-machine interaction, and reasoning from comprehensive multi-modal behavior data.","Title: Impact Of Filtering Generated Pseudo Bilingual Texts In Low-Resource Neural Machine Translation Enhancement: The Case Of Persian-Spanish\nYear: 2021\n\nAbstract: Although the Neural Machine Translation (NMT) framework has already been shown effective in large training data scenarios, it is less effective for low-resource conditions. To improve NMT performance in a low-resource setting, we extend the high-quality training data by generating a pseudo bilingual dataset and then filtering out low-quality alignments using a quality estimation based on back-translation. We demonstrate that our approach yields significantly higher BLEU scores than those of a set of baselines. (C) 2021 The Authors. Published by Elsevier B.V.","Title: From Stance to Concern: Adaptation of Propositional Analysis to New Tasks and Domains.\nYear: 2022\n\nAbstract: We present a generalized paradigm for adaptation of propositional analysis (predicate-argument pairs) to new tasks and domains. We leverage an analogy between stances (belief-driven sentiment) and concerns (topical issues with moral dimensions/endorsements) to produce an explanatory representation. A key contribution is the combination of semi-automatic resource building for extraction of domain-dependent concern types (with 2-4 hours of human labor per domain) and an entirely automatic procedure for extraction of domain-independent moral dimensions and endorsement values. Prudent (automatic) selection of terms from propositional structures for lexical expansion (via semantic similarity) produces new moral dimension lexicons at three levels of granularity beyond a strong baseline lexicon. We develop a ground truth (GT) based on expert annotators and compare our concern detection output to GT, to yield 231% improvement in recall over baseline, with only a 10% loss in precision. F1 yields 66% improvement over baseline and 97.8% of human performance. Our lexically based approach yields large savings over approaches that employ costly human labor and model building. We provide to the community a newly expanded moral dimension/value lexicon, annotation guidelines, and GT."],"string":"[\n \"Title: Computing Lexical Contrast.\\nYear: 2013\\n\\nAbstract: Knowing the degree of semantic contrast between words has widespread application in natural language processing, including machine translation, information retrieval, and dialogue systems. Manually created lexicons focus on opposites, such as hot and cold. Opposites are of many kinds such as antipodals, complementaries, and gradable. Existing lexicons often do not classify opposites into the different kinds, however. They also do not explicitly list word pairs that are not opposites but yet have some degree of contrast in meaning, such as warm and cold or tropical and freezing. We propose an automatic method to identify contrasting word pairs that is based on the hypothesis that if a pair of words, A and B, are contrasting, then there is a pair of opposites, C and D, such that A and C are strongly related and B and D are strongly related. (For example, there exists the pair of opposites hot and cold such that tropical is related to hot, and freezing is related to cold.) We will call this the contrast hypothesis.We begin with a large crowdsourcing experiment to determine the amount of human agreement on the concept of oppositeness and its different kinds. In the process, we flesh out key features of different kinds of opposites. We then present an automatic and empirical measure of lexical contrast that relies on the contrast hypothesis, corpus statistics, and the structure of a Roget-like thesaurus. We show how, using four different data sets, we evaluated our approach on two different tasks, solving most contrasting word questions and distinguishing synonyms from opposites. The results are analyzed across four parts of speech and across five different kinds of opposites. We show that the proposed measure of lexical contrast obtains high precision and large coverage, outperforming existing methods.\",\n \"Title: Interoperable query processing with multiple heterogeneous knowledge servers\\nYear: 1993\\n\\nAbstract: This paper describes a technique for infor- mation mediation when multiple heterogeneous knowl- edge and data servers are to be accessed during query processing. One problem is building an intelligent in- terface between each knowledge server (KS) and its processor (KP); and the second is to provide interoper- ability among multiple K P/KS so that a query may be answered using information from multiple sources. We present example scenarios which highlight these prob- lems and then outline query mapping and transforma- tion techniques that are applicable. The techniques for solving the interoperability problems involve rep- resentations in some canonical form. This includes a canonical represent ation (CR) corresponding to each KP/KS pair and a merged CR (MCR) to represent the mapping among the C%. The MCR and CRa include relevant information obtained from a source query, and heterogeneous mapping (bet-map) information, for all possible mappings among the multiple servers. The knowledge in the canonical form must be represented so that it can be easily accessed during query transfor- mation. We use an example of translating queries from an object schema to a relational schema to illustrate typical knowledge that must be represented in some canonical form. We use a high level logical language, F-logic, to represent the heterogeneous mapping (het- map) and query transformation information as a set of declarative rules, in the canonical form.\",\n \"Title: Leveraging reusability: cost-effective lexical acquisition for large-scale ontology translation\\nYear: 2006\\n\\nAbstract: Thesauri and ontologies provide important value in facilitating access to digital archives by representing underlying principles of organization. Translation of such resources into multiple languages is an important component for providing multilingual access. However, the specificity of vocabulary terms in most ontologies precludes fully-automated machine translation using general-domain lexical resources. In this paper, we present an efficient process for leveraging human translations when constructing domain-specific lexical resources. We evaluate the effectiveness of this process by producing a probabilistic phrase dictionary and translating a thesaurus of 56,000 concepts used to catalogue a large archive of oral histories. Our experiments demonstrate a cost-effective technique for accurate machine translation of large ontologies.\",\n \"Title: Generating targeted paraphrases for improved translation\\nYear: 2013\\n\\nAbstract: Today's Statistical Machine Translation (SMT) systems require high-quality human translations for parameter tuning, in addition to large bitexts for learning the translation units. This parameter tuning usually involves generating translations at different points in the parameter space and obtaining feedback against human-authored reference translations as to how good the translations. This feedback then dictates what point in the parameter space should be explored next. To measure this feedback, it is generally considered wise to have multiple (usually 4) reference translations to avoid unfair penalization of translation hypotheses which could easily happen given the large number of ways in which a sentence can be translated from one language to another. However, this reliance on multiple reference translations creates a problem since they are labor intensive and expensive to obtain. Therefore, most current MT datasets only contain a single reference. This leads to the problem of reference sparsity. In our previously published research, we had proposed the first paraphrase-based solution to this problem and evaluated its effect on Chinese-English translation. In this article, we first present extended results for that solution on additional source languages. More importantly, we present a novel way to generate “targeted” paraphrases that yields substantially larger gains (up to 2.7 BLEU points) in translation quality when compared to our previous solution (up to 1.6 BLEU points). In addition, we further validate these improvements by supplementing with human preference judgments obtained via Amazon Mechanical Turk.\",\n \"Title: Handling Translation Divergences: Combining Statistical and Symbolic Techniques in Generation-Heavy Machine Translation\\nYear: 2002\\n\\nAbstract: This paper describes a novel approach to handling translation divergences in a Generation-Heavy Hybrid Machine Translation (GHMT) system. The translation divergence problem is usually reserved for Transfer and Interlingual MT because it requires a large combination of complex lexical and structural mappings. A major requirement of these approaches is the accessibility of large amounts of explicit symmetric knowledge for both source and target languages. This limitation renders Transfer and Interlingual approaches ineffective in the face of structurally-divergent language pairs with asymmetric resources. GHMT addresses the more common form of this problem, source-poor/targetrich, by fully exploiting symbolic and statistical target-language resources. This non-interlingual non-transfer approach is accomplished by using target-language lexical semantics, categorial variations and subcategorization frames to overgenerate multiple lexico-structural variations from a target-glossed syntactic dependency of the source-language sentence. The symbolic overgeneration, which accounts for different possible translation divergences, is constrained by a statistical target-language model.\",\n \"Title: A maximum entropy approach to combining word alignments\\nYear: 2006\\n\\nAbstract: This paper presents a new approach to combining outputs of existing word alignment systems. Each alignment link is represented with a set of feature functions extracted from linguistic features and input alignments. These features are used as the basis of alignment decisions made by a maximum entropy approach. The learning method has been evaluated on three language pairs, yielding significant improvements over input alignments and three heuristic combination methods. The impact of word alignment on MT quality is investigated, using a phrase-based MT system.\",\n \"Title: Leveraging Recurrent Phrase Structure in Large-scale Ontology Translation\\nYear: 2006\\n\\nAbstract: This paper presents a process for leveraging structural relationships and reusable phrases when translating large-scale ontologies. Digital libraries are becoming more and more prevalent. An important step in providing universal access to such material is to pro- vide multi-lingual access to the underlying principles of organization via ontologies, thesauri, and controlled vocabularies. Machine translation of these resources requires high accuracy and a deep vocabulary. Human input is often required, but full manual translation can be slow and expensive. We report on a cost-effective approach to ontology translation. We describe our technique of prioritization, our process of collecting aligned translations and generating a new lexicon, and the resulting improvement to translation system output. Our preliminary evaluation indicates that this technique provides significant cost savings for human-assisted translation. The process we developed can be applied to ontologies in other domains and is easily incorporated into other translation systems.\",\n \"Title: DUSTer: A Method for Unraveling Cross-Language Divergences for Statistical Word-Level Alignment\\nYear: 2002\\n\\nAbstract: The frequent occurrence of divergences--structural differences between languages--presents a great challenge for statistical word-level alignment. In this paper, we introduce DUSTer, a method for systematically identifying common divergence types and transforming an English sentence structure to bear a closer resemblance to that of another language. Our ultimate goal is to enable more accurate alignment and projection of dependency trees in another language without requiring any training on dependency-tree data in that language. We present an empirical analysis comparing the complexities of performing word-level alignments with and without divergence handling. Our results suggest that our approach facilitates word-level alignment, particularly for sentence pairs containing divergences.\",\n \"Title: Cross-Language Access to Recorded Speech in the MALACH Project\\nYear: 2002\\n\\nAbstract: The MALACH project seeks to help users find information in a vast multilingual collections of untranscribed oral history interviews. This paper introduces the goals of the project and focuses on supporting access by users who are unfamiliar with the interview language. It begins with a review of the state of the art in cross-language speech retrieval; approaches that will be investigated in the project are then described. Czech was selected as the first non-English language to be supported, so results of an initial experiment with Czech/English cross-language retrieval are reported.\",\n \"Title: Interlingual machine translation: a parameterized approach\\nYear: 1993\\n\\nAbstract: The task of designing a machine translation system is difficult because, in order to achieve any degree of accuracy, such systems must capture language-independent information while still systematically processing many types of language-specific phenomena in each of the individual languages. This paper provides a catalog of certain types of distinctions among Spanish, English, and German, and describes a parameterized interlingual approach that characterizes these distinctions, both at the syntactic level and at the lexical-semantic level. The parameter-setting approach to machine translation is desirable because it simplifies the descriptions of natural grammars, facilitates the task of modifying and augmenting the system, accounts for cross-linguistic variation uniformly, and provides a more constrained theory of processing. The approach described here is implemented in a system called UNITRAN, an interlingual machine translation system that translates English, Spanish, and German bidirectionally.\",\n \"Title: Modality and negation in simt use of modality and negation in semantically-informed syntactic mt\\nYear: 2012\\n\\nAbstract: This article describes the resource-and system-building efforts of an 8-week Johns Hopkins University Human Language Technology Center of Excellence Summer Camp for Applied Language Exploration (SCALE-2009) on Semantically Informed Machine Translation (SIMT). We describe a new modality/negation (MN) annotation scheme, the creation of a (publicly available) MN lexicon, and two automated MN taggers that we built using the annotation scheme and lexicon. Our annotation scheme isolates three components of modality and negation: a trigger (a word that conveys modality or negation), a target (an action associated with modality or negation), and a holder (an experiencer of modality). We describe how our MN lexicon was semi-automatically produced and we demonstrate that a structure-based MN tagger results in precision around 86% (depending on genre) for tagging of a standard LDC data set. We apply our MN annotation scheme to statistical machine translation using a syntactic framework that supports the inclusion of semantic annotations. Syntactic tags enriched with semantic annotations are assigned to parse trees in the target-language training texts through a process of tree grafting. Although the focus of our work is modality and negation, the tree grafting procedure is general and supports other types of semantic information. We exploit this capability by including named entities, produced by a pre-existing tagger, in addition to the MN elements produced by the taggers described here. The resulting system significantly outperformed a linguistically naive baseline model (Hiero), and reached the highest scores yet reported on the NIST 2009 Urdu-English test set. This finding supports the hypothesis that both syntactic and semantic information can improve translation quality.\",\n \"Title: Exploiting aspectual features and connecting words for summarization-inspired temporal-relation extraction\\nYear: 2007\\n\\nAbstract: This paper presents a model that incorporates contemporary theories of tense and aspect and develops a new framework for extracting temporal relations between two sentence-internal events, given their tense, aspect, and a temporal connecting word relating the two events. A linguistic constraint on event combination has been implemented to detect incorrect parser analyses and potentially apply syntactic reanalysis or semantic reinterpretation-in preparation for subsequent processing for multi-document summarization. An important contribution of this work is the extension of two different existing theoretical frameworks-Hornstein's 1990 theory of tense analysis and Allen's 1984 theory on event ordering-and the combination of both into a unified system for representing and constraining combinations of different event types (points, closed intervals, and open-ended intervals). We show that our theoretical results have been verified in a large-scale corpus analysis. The framework is designed to inform a temporally motivated sentence-ordering module in an implemented multi-document summarization system.\",\n \"Title: Cross-language headline generation for Hindi\\nYear: 2003\\n\\nAbstract: This paper presents new approaches to headline generation for English newspaper texts, with an eye toward the production of document surrogates for document selection in cross-language information retrieval. This task is difficult because the user must make decisions about relevance based on (often poor) translations of retrieved documents. To facilitate the decision-making process we need translations that can be assessed rapidly and accurately; our approach is to provide an English headline for the non-English document. We describe two approaches to headline generation and their application to the recent DARPA TIDES-2003 Surprise Language Exercise for Hindi. For comparison, we also implemented an alternative method for surrogate generation: a system that produces topic lists for (Hindi) articles. We present the results of a series of experiments comparing each of these approaches. We demonstrate in both automatic and human evaluations that our linguistically motivated approach outperforms two other surrogate-generation methods: a statistical system and a topic discovery system.\",\n \"Title: Machine translation of spatial expressions: defining the relation between an interlingua and a knowledge representation system\\nYear: 1993\\n\\nAbstract: In this paper we present one aspect of our research on machine translation (MT): defining the relation between the interlingua (IL) and a knowledge representation (KR) within an MT system. Our interest lies in the translation of natural language (NL) sentences where the \\\"message\\\" contains a spatial relation - in particular, where the sentence conveys information about the location or path of physical entities in the real, physical world. We explore several arguments for clarifying the source of constraints on the particular IL structures needed to translate these sentences. This paper develops one approach to defining these constraints and building an MT system where the IL structures designed to satisfy these constraints may be tested. In this way, we have begun to address one of the basic issues in MT research, providing independent justification for the IL itself.\",\n \"Title: Lexical Selection for Cross-Language Applications: Combining LCS with WordNet\\nYear: 1998\\n\\nAbstract: This paper describes experiments for testing the power of large-scale resources for lexical selection in machine translation (MT) and cross-language information retrieval (CLIR). We adopt the view that verbs with similar argument structure share certain meaning components, but that those meaning components are more relevant to argument realization than to idiosyncratic verb meaning. We verify this by demonstrating that verbs with similar argument structure as encoded in Lexical Conceptual Structure (LCS) are rarely synonymous in WordNet. We then use the results of this work to guide our implementation of an algorithm for cross-language selection of lexical items, exploiting the strengths of each resource: LCS for semantic structure and WordNet for semantic content. We use the Parka Knowledge-Based System to encode LCS representations and WordNet synonym sets and we implement our lexical-selection algorithm as Parka-based queries into a knowledge base containing both information types.\",\n \"Title: Iterative translation disambiguation for cross-language information retrieval\\nYear: 2005\\n\\nAbstract: Finding a proper distribution of translation probabilities is one of the most important factors impacting the effectiveness of a cross-language information retrieval system. In this paper we present a new approach that computes translation probabilities for a given query by using only a bilingual dictionary and a monolingual corpus in the target language. The algorithm combines term association measures with an iterative machine learning approach based on expectation maximization. Our approach considers only pairs of translation candidates and is therefore less sensitive to data-sparseness issues than approaches using higher n-grams. The learned translation probabilities are used as query term weights and integrated into a vector-space retrieval system. Results for English-German cross-lingual retrieval show substantial improvements over a baseline using dictionary lookup without term weighting.\",\n \"Title: Enhancing Automatic Acquisition of the Thematic Structure in a Large-Scale Lexicon for Mandarin Chinese\\nYear: 1998\\n\\nAbstract: This paper describes a refinement to our procedure for porting lexical conceptual structure (LCS) into new languages. Specifically we describe a two-step process for creating candidate thematic grids for Mandarin Chinese verbs, using the English verb heading the VP in the subdefinitions to separate senses, and roughly parsing the verb complement structure to match thematic structure templates. We accomplished a substantial reduction in manual effort, without substantive loss. The procedure is part of a larger process of creating a usable lexicon for interlingual machine translation from a large on-line resource with both too much and too little information.\",\n \"Title: NeurAlign: combining word alignments using neural networks\\nYear: 2005\\n\\nAbstract: This paper presents a novel approach to combining different word alignments. We view word alignment as a pattern classification problem, where alignment combination is treated as a classifier ensemble, and alignment links are adorned with linguistic features. A neural network model is used to learn word alignments from the individual alignment systems. We show that our alignment combination approach yields a significant 20--34% relative error reduction over the best-known alignment combination technique on English-Spanish and English-Chinese data.\",\n \"Title: Alignment link projection using transformation-based learning\\nYear: 2005\\n\\nAbstract: We present a new word-alignment approach that learns errors made by existing word alignment systems and corrects them. By adapting transformation-based learning to the problem of word alignment, we project new alignment links from already existing links, using features such as POS tags. We show that our alignment link projection approach yields a significantly lower alignment error rate than that of the best performing alignment system (22.6% relative reduction on English-Spanish data and 23.2% relative reduction on English-Chinese data).\",\n \"Title: Building a Chinese-English Mapping between Verb Concepts for Multilingual Applications\\nYear: 2000\\n\\nAbstract: This paper addresses the problem of building conceptual resources for multilingual applications. We describe new techniques for large-scale construction of a Chinese-English lexicon for verbs, using thematic-role information to create links between Chinese and English conceptual information. We then present an approach to compensating for gaps in the existing resources. The resulting lexicon is used for multilingual applications such as machine translation and cross-language information retrieval.\",\n \"Title: Query transformation techniques for interoperable query processing in cooperative information systems\\nYear: 1994\\n\\nAbstract: : This paper describes a technique to support interoperable queryprocessing, when multiple heterogeneous servers are accessed in a cooperativeinformation system (CoopIS). The problem is to support query transformationtransparently, so a user can pose queries locally, without needingglobal knowledge about different data models and schema in the CoopIS.An architecture for supporting interoperability is described and we providesome details of transforming queries from an object schema...\",\n \"Title: A Survey of Current Paradigms in Machine Translation\\nYear: 1999\\n\\nAbstract: Abstract This paper is a survey of the current machine translation research in the US, Europe and Japan. A short history of machine translation is presented first, followed by an overview of the current research work. Representative examples of a wide range of different approaches adopted by machine translation researchers are presented. These are described in detail along with a discussion of the practicalities of scaling up these approaches for operational environments. In support of this discussion, issues in, and techniques for, evaluating machine translation systems are addressed.\",\n \"Title: Large-scale acquisition of LCS-based lexicons for foreign language tutoring\\nYear: 1997\\n\\nAbstract: We focus on the problem of building large repositories of lexical conceptual structure (LCS) representations for verbs in multiple languages. One of the man results of this work is the definition of a relation between broad semantic classes and LCS meaning components. Our acquisition program---LEXICALL---takes, as input, the result of previous work on verb classification and thematic grid tagging, and outputs LCS representations for different languages. These representations have been ported into English. Arabic and Spanish lexicons, each containing approximately 9000 verbs. We are currently using these lexicons in an operational foreign language tutoring and machine translation.\",\n \"Title: A cost-effective lexical acquisition process for large-scale thesaurus translation\\nYear: 2009\\n\\nAbstract: Thesauri and controlled vocabularies facilitate access to digital collections by explicitly representing the underlying principles\\n of organization. Translation of such resources into multiple languages is an important component for providing multilingual\\n access. However, the specificity of vocabulary terms in most thesauri precludes fully-automatic translation using general-domain\\n lexical resources. In this paper, we present an efficient process for leveraging human translations to construct domain-specific\\n lexical resources. This process is illustrated on a thesaurus of 56,000 concepts used to catalog a large archive of oral histories.\\n We elicited human translations on a small subset of concepts, induced a probabilistic phrase dictionary from these translations,\\n and used the resulting resource to automatically translate the rest of the thesaurus. Two separate evaluations demonstrate\\n the acceptability of the automatic translations and the cost-effectiveness of our approach.\",\n \"Title: Are Multiple Reference Translations Necessary? Investigating the Value of Paraphrased Reference Translations in Parameter Optimization\\nYear: 2008\\n\\nAbstract: Abstract Most state-of-the-art statistical machine trans- lation systems use log-linear models, which are defined in terms of hypothesis features and weights for those features. It is standard to tune the feature weights in order to maxi- mize a translation quality metric, using held- out test sentences and their corresponding ref- erence translations. However, obtaining refer- ence translations is expensive. In our earlier work (Madnani et al., 2007), we introduced a new full-sentence paraphrase technique, based on English-to-English decoding with an MT system, and demonstrated that the resulting paraphrases can be used to cut the number,of human,reference translations needed in half. In this paper, we take the idea a step further, asking how far it is possible to get with just a single good reference translation for each item in the development,set. Our analysis suggests that it is necessary to invest in four or more hu- man translations in order to significantly im- prove on a single translation augmented,by monolingual,paraphrases.\",\n \"Title: The ACL Anthology Reference Corpus: A Reference Dataset for Bibliographic Research in Computational Linguistics\\nYear: 2008\\n\\nAbstract: The ACL Anthology is a digital archive of conference and journal papers in natural language processing and computational linguistics. Its primary purpose is to serve as a reference repository of research results, but we believe that it can also be an object of study and a platform for research in its own right. We describe an enriched and standardized reference corpus derived from the ACL Anthology that can be used for research in scholarly document processing. This corpus, which we call the ACL Anthology Reference Corpus (ACL ARC), brings together the recent activities of a number of research groups around the world. Our goal is to make the corpus widely available, and to encourage other researchers to use it as a standard testbed for experiments in both bibliographic and bibliometric research.\",\n \"Title: Generation-heavy hybrid machine translation\\nYear: 2002\\n\\nAbstract: The state of the art techniques in Machine Translation (MT) require large amounts of symmetric resources from source and target languages. This is true regardless of whether the approach is Transfer or Interlingua, Symbolic or Statistical. Symmetry within these approaches is necessary to ensure quality, robustness and retargetability. In reality, such symmetry, whether it is in terms of structural transfer lexicons, interlingual dictionaries or parallel corpora, is a major bottleneck in developing any MT system. This dissertation presents an approach to MT that addresses the lack of symmetry by exploiting symbolic and statistical target language resources in source-poor/target-rich language pairs. This approach is called Generation-Heavy Hybrid Machine Translation (GHMT). Expected source language resources include a syntactic parser and a simple one-to-many translation dictionary. No transfer rules or complex interlingual representations are used. Rich target language symbolic resources are used to overgenerate multiple structural variations from a target-glossed syntactic dependency representation of source language sentences. Statistical target-language resource are then used to select amongst the overgenerated translations. The source-target asymmetry of systems developed in this approach makes them more easily retargetable to new source languages. The contributions of this research include: (1) a new model for machine translation that transcends the need for large amounts of symmetric knowledge while maintaining a high degree of robustness, quality, and retargetability; (2) a systematic framework for handling translation divergences that uniformly accommodates a wide range of seemingly different divergence types and their interactions; (3) a hybrid (symbolic-statistical) generation approach that expands the concept of symbolic overgeneration to include conflation and head-swapping of structural variations; (4) the introduction and use of structural n-grams on a large scale in natural language generation; and (5) the creation of several resources that have been used by other researchers including an extensible MT system for translating into English and a large-scale categorical variation database for English. An extensive evaluation suggests that GHMT is more robust and has superior output quality, in terms of grammaticality and accuracy, relative to a primarily statistical approach.\",\n \"Title: Language and translation model adaptation using comparable corpora\\nYear: 2008\\n\\nAbstract: Traditionally, statistical machine translation systems have relied on parallel bi-lingual data to train a translation model. While bi-lingual parallel data are expensive to generate, monolingual data are relatively common. Yet monolingual data have been under-utilized, having been used primarily for training a language model in the target language. This paper describes a novel method for utilizing monolingual target data to improve the performance of a statistical machine translation system on news stories. The method exploits the existence of comparable text---multiple texts in the target language that discuss the same or similar stories as found in the source language document. For every source document that is to be translated, a large monolingual data set in the target language is searched for documents that might be comparable to the source documents. These documents are then used to adapt the MT system to increase the probability of generating texts that resemble the comparable document. Experimental results obtained by adapting both the language and translation models show substantial gains over the baseline system.\",\n \"Title: Interlingual Annotation for MT Development\\nYear: 2004\\n\\nAbstract: MT systems that use only superficial representations, including the current generation of statistical MT systems, have been successful and useful. However, they will experience a plateau in quality, much like other \\\"silver bullet\\\" approaches to MT. We pursue work on the development of interlingual representations for use in symbolic or hybrid MT systems. In this paper, we describe the creation of an interlingua and the development of a corpus of semantically annotated text, to be validated in six languages and evaluated in several ways. We have established a distributed, well-functioning research methodology, designed a preliminary interlingua notation, created annotation manuals and tools, developed a test collection in six languages with associated English translations, annotated some 150 translations, and designed and applied various annotation metrics. We describe the data sets being annotated and the interlingual (IL) representation language which uses two ontologies and a systematic theta-role list. We present the annotation tools built and outline the annotation process. Following this, we describe our evaluation methodology and conclude with a summary of issues that have arisen.\",\n \"Title: Selecting tense aspect and connecting words in language generation\\nYear: 1995\\n\\nAbstract: Generating language that reflects the temporal organization of represented knowledge requires a language generation model chat integrates contemporary theories of tense and aspect, temporal representations, and methods to plan text This paper presents a model that produces complex sentences that reflect temporal relations present in underlying temporal concepts The mam result of this work is the successful application of constrained linguistic theories of tense and aspect to a generator which produces meaningful event combinations and selects appropriate connecting words that relate them.\",\n \"Title: Single-document and multi-document summarization techniques for email threads using sentence compression\\nYear: 2008\\n\\nAbstract: We present two approaches to email thread summarization: collective message summarization (CMS) applies a multi-document summarization approach, while individual message summarization (IMS) treats the problem as a sequence of single-document summarization tasks. Both approaches are implemented in our general framework driven by sentence compression. Instead of a purely extractive approach, we employ linguistic and statistical methods to generate multiple compressions, and then select from those candidates to produce a final summary. We demonstrate these ideas on the Enron email collection - a very challenging corpus because of the highly technical language. Experimental results point to two findings: that CMS represents a better approach to email thread summarization, and that current sentence compression techniques do not improve summarization performance in this genre.\",\n \"Title: Multi-align: Combining Linguistic and Statistical Techniques to Improve Alignments for Adaptable MT\\nYear: 2004\\n\\nAbstract: An adaptable statistical or hybrid TAT system relies heavily on the quality of word-level alignments of real-world data. Statistical alignment approaches provide a reasonable initial estimate for word alignment. However, they cannot handle certain types of linguistic phenomena such as long-distance dependencies and structural differences between languages. We address this issue in Multi-Align, a new framework for incremental testing of different alignment algorithms and their combinations. Our design allows users to tune their systems to the properties of a particular genre/domain while still benefiting from general linguistic knowledge associated with a language pair. We demonstrate that a combination of statistical and linguistically-informed alignments can resolve translation divergences during the alignment process.\",\n \"Title: Multilingual generation: The role of telicity in lexical choice and syntactic realization\\nYear: 1996\\n\\nAbstract: . Multilingual generation in machine translation (MT) requires a knowledgeorganization that facilitates the task of lexical choice, i.e., selection of lexicalunits to be used in the generation of a target-language sentence. This paper investigatesthe extent to which lexicalization patterns involving the lexical aspect feature[+telic] (`having an inherent end\\\" as in win vs. run) may be used for translatingevents and states among languages. The work reported here is part of an ongoingeffort ...\",\n \"Title: A parameterized approach to integrating aspect with lexical-semantics for machine translation\\nYear: 1992\\n\\nAbstract: This paper discusses how a two-level knowledge rep- resentation model for machine translation integrates as- pectual information with lexical-semantic information by means of parameterization. The integration of aspect with lexical-semantics is especially critical in machine translation because of the lexical selection and aspec- tual realization processes that operate during the pro- duction of the target-language sentence: there are of- ten a large number of lexical and aspectual possibili- ties to choose from in the production of a sentence from a lexical semantic representation. Aspectual informa- tion from the source-language sentence constrains the choice of target-language terms. In turn, the target- language terms limit the possibilities for generation of aspect. Thus, there is a two-way communication chan- nel between the two processes. This paper will show that the selection/realization processes may be parame- terized so that they operate uniformly across more than one language and it will describe how the parameter- based approach is currently being used as the basis for extraction of aspectual information from corpora.\",\n \"Title: Mapping lexical entries in a verbs database to WordNet senses\\nYear: 2001\\n\\nAbstract: This paper describes automatic techniques for mapping 9611 entries in a database of English verbs to WordNet senses. The verbs were initially grouped into 491 classes based on syntactic features. Mapping these verbs into WordNet senses provides a resource that supports disambiguation in multilingual applications such as machine translation and cross-language information retrieval. Our techniques make use of (1) a training set of 1791 disambiguated entries, representing 1442 verb entries from 167 classes; (2) word sense probabilities, from frequency counts in a tagged corpus; (3) semantic similarity of WordNet senses for verbs within the same class; (4) probabilistic correlations between WordNet data and attributes of the verb classes. The best results achieved 72% precision and 58% recall, versus a lower bound of 62% precision and 38% recall for assigning the most frequently occurring WordNet sense, and an upper bound of 87% precision and 75% recall for human judgment.\",\n \"Title: Machine translation divergences: a formal description and proposed solution\\nYear: 1994\\n\\nAbstract: There are many cases in which the natural translation of one language into another results in a very different form than that of the original. The existence of translation divergences (i.e., crosslinguistic distinctions) makes the straightforward transfer from source structures into target structures impractical. Many existing translation systems have mechanisms for handling divergent structures but do not provide a general procedure that takes advantage of takes advantage of the systematic relation between lexical-semantic structure and syntactic structure. This paper demonstrates that a systematic solution to the divergence problem can be derived from the formalization of two types of information: (1) the linguistically grounded classes upon which lexical-semantic divergences are based; and (2) the techniques by which lexical-semantic divergences are resolved. This formalization is advantageous in that it facilitates the design and implementation of the system, allows one to make an evaluation of the status of the system, and provides a basis for proving certain important properties about the system.\",\n \"Title: Chinese-English Semantic Resource Construction\\nYear: 2000\\n\\nAbstract: We describe an approach to large-scale construction of a semantic lexicon for Chinese verbs. We leverage off of three existing resources— a classification of English verbs called EVCA (English Verbs Classes and Alternations) (Levin, 1993), a Chinese conceptual database called HowNet (Zhendong, 1988c; Zhendong, 1988b; Zhendong, 1988a) (http://www .how-net.com), and a large machine-readable dic- tionary called Optilex. The resulting lexicon is used for determining appropriate word senses in applications such as machine translation and cross-language information retrieval.\",\n \"Title: Rapid porting of DUSTer to Hindi\\nYear: 2003\\n\\nAbstract: The frequent occurrence of divergences—structural differences between languages---presents a great challenge for statistical word-level alignment and machine translation. This paper describes the adaptation of DUSTer, a divergence unraveling package, to Hindi during the DARPA TIDES-2003 Surprise Language Exercise. We show that it is possible to port DUSTer to Hindi in under 3 days.\",\n \"Title: Efficient parsing for Korean and English: a parameterized message-passing approach\\nYear: 1995\\n\\nAbstract: This article presents an efficient, implemented approach to cross-linguistic parsing basedon Government-Binding (GB) Theory (Chomsky, 1986) and followers. One of the drawbacksto alternative GB-based parsing approaches is that they generally adopt a filterbasedparadigm. These approaches typically generate all possible candidate structuresof the sentence that satisfy X theory, and then subsequently apply filters in order toeliminate those structures that violate GB principles. (See, for...\",\n \"Title: Reranking for Sentence Boundary Detection in Conversational Speech\\nYear: 2006\\n\\nAbstract: We present a reranking approach to sentence-like unit (SU) boundary detection, one of the EARS metadata extraction tasks. Techniques for generating relatively small n-best lists with high oracle accuracy are presented. For each candidate, features are derived from a range of information sources, including the output of a number of parsers. Our approach yields significant improvements over the best performing system from the NIST RT-04F community evaluation\",\n \"Title: A Methodology for Extrinsic Evaluation of Text Summarization: Does ROUGE Correlate?\\nYear: 2005\\n\\nAbstract: This paper demonstrates the usefulness of sum- maries in an extrinsic task of relevance judgment based on a new method for measuring agree- ment, Relevance-Prediction, which compares sub- jects' judgments on summaries with their own judg- ments on full text documents. We demonstrate that, because this measure is more reliable than previ- ous gold-standard measures, we are able to make stronger statistical statements about the benefits of summarization. We found positive correlations be- tween ROUGE scores and two different summary types, where only weak or negative correlations were found using other agreement measures. How- ever, we show that ROUGE may be sensitive to the choice of summarization style. We discuss the im- portance of these results and the implications for fu- ture summarization evaluations.\",\n \"Title: The use of lexical semantics in interlingual machine translation\\nYear: 1992\\n\\nAbstract: This paper describes the lexical-semantic basis for UNITRAN, an implemented scheme for translating Spanish, English, and German bidirectionally. Two claims made here are that the current representation handles many distinctions (or divergences) across languages without recourse to language-specific rules and that the lexical-semantic framework provides the basis for a systematic mapping between the interlingua and the syntactic structure. The representation adopted is an extended version of lexical conceptual structure which is suitable to the task of translating between divergent structures for two reasons: (1) it provides an abstraction of language-independent properties from structural idiosyncrasies; and (2) it is compositional in nature. The lexical-semantic approach addresses the divergence problem by using a linguistically grounded mapping that has access to parameter settings in the lexicon. We will examine a number of relevant issues including the problem of defining primitives, the issue of interlinguality, the cross-linguistic coverage of the system, and the mapping between the syntactic structure and the interlingua. A detailed example of lexical-semantic composition will be presented.\",\n \"Title: Task-based evaluation of text summarization using Relevance Prediction\\nYear: 2007\\n\\nAbstract: This article introduces a new task-based evaluation measure called Relevance Prediction that is a more intuitive measure of an individual's performance on a real-world task than interannotator agreement. Relevance Prediction parallels what a user does in the real world task of browsing a set of documents using standard search tools, i.e., the user judges relevance based on a short summary and then that same user-not an independent user-decides whether to open (and judge) the corresponding document. This measure is shown to be a more reliable measure of task performance than LDC Agreement, a current gold-standard based measure used in the summarization evaluation community. Our goal is to provide a stable framework within which developers of new automatic measures may make stronger statistical statements about the effectiveness of their measures in predicting summary usefulness. We demonstrate-as a proof-of-concept methodology for automatic metric developers-that a current automatic evaluation measure has a better correlation with Relevance Prediction than with LDC Agreement and that the significance level for detected differences is higher for the former than for the latter.\",\n \"Title: Evaluating Resources for Query Translation in Cross-Language Information Retrieval\\nYear: 1998\\n\\nAbstract: Our goal is to evaluate the utility of a lexical resource containing Lexical Conceptual Structures (LCS) for use in cross-language information retrieval. Our evaluation makes use of a combination of techniques from interlingual machine translation (Dorr, 1993) with conventional information retrieval techniques (Oard, 1996; Oard and Dorr, 1996). Given a query in one language, we transform the query into the corresponding terms in a second language. We evaluate this approach by comparing the...\",\n \"Title: Toward a lexicalized grammar for interlinguas\\nYear: 1995\\n\\nAbstract: . In this paper we present one aspect of our research on machine translation (MT):capturing the grammatical and computational relation between (i) the interlingua (IL) as defineddeclaratively in the lexicon and (ii) the IL as defined procedurally by way of algorithms thatcompose and decompose pivot IL forms. We begin by examining the interlinguas in the lexicons ofa variety of current IL-based approaches to MT. This brief survey makes it clear that no consensusexists among MT researchers...\",\n \"Title: A Two-Level Knowledge Representation for Machine Translation: Lexical Semantics and Tense/Aspect\\nYear: 1991\\n\\nAbstract: Abstract This paper proposes a two-level model that integrates tense and aspect information, based on theories by both Hornstein (in the spirit of Reichenbach) and Allen, with lexicai-semantic information based on an extended,version of $ackendoff's theory that includes a verb classification system,proposed,by Dowty and Vendler. The model is intended to be extensible to realms outside of the temporal domain (e.g., the spatial domain). The integration of tense and aspect with lexical-semantics is especially critical in machine,translation because of the lexical selection process during generation: there is often a number,of lexical connective and tense/aspect possibilities that may be produced from a lexical semantic representation, which, as defined in the model presented here, is largely underspecified. The use of tense and aspect information allows the choice of target-language terms to be more finely tuned and the combination,of event structures to be more carefully constrained.\",\n \"Title: A Thematic Hierarchy for Efficient Generation from Lexical-Conceptual Structure\\nYear: 1998\\n\\nAbstract: This paper describes an implemented algorithm for syntactic realization of a target-language sentence from an interlingual representation called Lexical Conceptual Structure (LCS). We provide a mapping between LCS thematic roles and Abstract Meaning Representation (AMR) relations; these relations serve as input to an off-the-shelf generator (Nitrogen). There are two contributions of this work: (1) the development of a thematic hierarchy that provides ordering information for realization of arguments in their surface positions; (2) the provision of a diagnostic tool for detecting inconsistencies in an existing online LCS-based lexicon that allows us to enhance principles for thematic-role assignment.\",\n \"Title: Role of word sense disambiguation in lexical acquisition: predicting semantics from syntactic cues\\nYear: 1996\\n\\nAbstract: This paper addresses the issue of word-sense ambiguity in extraction from machine-readable resources for the construction of large-scale knowledge sources. We describe two experiments: one which ignored word-sense distinctions, resulting in 6.3% accuracy for semantic classification of verbs based on (Levin, 1993); and one which exploited word-sense distinctions, resulting in 97.9% accuracy. These experiments were dual purpose: (1) to validate the central thesis of the work of (Levin, 1993), i.e., that verb semantics and syntactic behavior are predictably related; (2) to demonstrate that a 15-fold improvement can be achieved in deriving semantic information from syntactic cues if we first divide the syntactic cues into distinct groupings that correlate with different word senses. Finally, we show that we can provide effective acquisition techniques for novel word senses using a combination of online sources.\",\n \"Title: Generating phrasal and sentential paraphrases: A survey of data-driven methods\\nYear: 2010\\n\\nAbstract: The task of paraphrasing is inherently familiar to speakers of all languages. Moreover, the task of automatically generating or extracting semantic equivalences for the various units of language-words, phrases, and sentences-is an important part of natural language processing (NLP) and is being increasingly employed to improve the performance of several NLP applications. In this article, we attempt to conduct a comprehensive and application-independent survey of data-driven phrasal and sentential paraphrase generation methods, while also conveying an appreciation for the importance and potential use of paraphrases in the field of NLP research. Recent work done in manual and automatic construction of paraphrase corpora is also examined. We also discuss the strategies used for evaluating paraphrase generation techniques and briefly explore some future trends in paraphrase generation.\",\n \"Title: Putting the user in the loop: interactive Maximal Marginal Relevance for query-focused summarization\\nYear: 2010\\n\\nAbstract: This work represents an initial attempt to move beyond \\\"single-shot\\\" summarization to interactive summarization. We present an extension to the classic Maximal Marginal Relevance (MMR) algorithm that places a user \\\"in the loop\\\" to assist in candidate selection. Experiments in the complex interactive Question Answering (ciQA) task at TREC 2007 show that interactively-constructed responses are significantly higher in quality than automatically-generated ones. This novel algorithm provides a starting point for future work on interactive summarization.\",\n \"Title: Fluency, adequacy, or HTER?: exploring different human judgments with a tunable MT metric\\nYear: 2009\\n\\nAbstract: Automatic Machine Translation (MT) evaluation metrics have traditionally been evaluated by the correlation of the scores they assign to MT output with human judgments of translation performance. Different types of human judgments, such as Fluency, Adequacy, and HTER, measure varying aspects of MT performance that can be captured by automatic MT metrics. We explore these differences through the use of a new tunable MT metric: TER-Plus, which extends the Translation Edit Rate evaluation metric with tunable parameters and the incorporation of morphology, synonymy and paraphrases. TER-Plus was shown to be one of the top metrics in NIST's Metrics MATR 2008 Challenge, having the highest average rank in terms of Pearson and Spearman correlation. Optimizing TER-Plus to different types of human judgments yields significantly improved correlations and meaningful changes in the weight of different types of edits, demonstrating significant differences between the types of human judgments.\",\n \"Title: A first-pass approach for evaluating machine translation systems\\nYear: 1993\\n\\nAbstract: This paper describes a short-term survey and evaluationproject that covered a large number of machine translation productsand research. We discuss our evaluation approach and addresscertain issues and implications relevant to our findings.We represented a variety of potential users of MT systems andwere faced with the task of identifying which systems would besthelp them solve their translation problems.1 IntroductionDuring 1991, The MITRE Corp.1surveyed and evaluated machine...\",\n \"Title: Measuring variability in sentence ordering for news summarization\\nYear: 2007\\n\\nAbstract: The issue of sentence ordering is an important one for natural language tasks such as multi-document summarization, yet there has not been a quantitative exploration of the range of acceptable sentence orderings for short texts. We present results of a sentence reordering experiment with three experimental conditions. Our findings indicate a very high degree of variability in the orderings that the eighteen subjects produce. In addition, the variability of reorderings is significantly greater when the initial ordering seen by subjects is different from the original summary. We conclude that evaluation of sentence ordering should use multiple reference orderings. Our evaluation presents several metrics that might prove useful in assessing against multiple references. We conclude with a deeper set of questions: (a) what sorts of independent assessments of quality of the different reference orderings could be made and (b) whether a large enough test set would obviate the need for such independent means of quality assessment.\",\n \"Title: Interpretation of Compound Nominals Using WordNet\\nYear: 2001\\n\\nAbstract: We describe an approach to interpreting noun-noun compounds within a question answering system. The system's lexicon, based on WordNet, provides the basis for heuristics that group noun-noun compounds with semantically similar words. The semantic relationship between the nouns in a compound is determined by the choice of heuristic for the compound. We discuss procedures for selecting one heuristic in cases where several can apply to a compound, the effects of lexical ambiguity, and some initial results of our methods.\",\n \"Title: Going beyond AER: an extensive analysis of word alignments and their impact on MT\\nYear: 2006\\n\\nAbstract: This paper presents an extensive evaluation of five different alignments and investigates their impact on the corresponding MT system output. We introduce new measures for intrinsic evaluations and examine the distribution of phrases and untranslated words during decoding to identify which characteristics of different alignments affect translation. We show that precision-oriented alignments yield better MT output (translating more words and using longer phrases) than recall-oriented alignments.\",\n \"Title: Multi-candidate reduction: Sentence compression as a tool for document summarization tasks\\nYear: 2007\\n\\nAbstract: This article examines the application of two single-document sentence compression techniques to the problem of multi-document summarization-a ''parse-and-trim'' approach and a statistical noisy-channel approach. We introduce the multi-candidate reduction (MCR) framework for multi-document summarization, in which many compressed candidates are generated for each source sentence. These candidates are then selected for inclusion in the final summary based on a combination of static and dynamic features. Evaluations demonstrate that sentence compression is a valuable component of a larger multi-document summarization framework.\",\n \"Title: Generating extractive summaries of scientific paradigms\\nYear: 2013\\n\\nAbstract: Researchers and scientists increasingly find themselves in the position of having to quickly understand large amounts of technical material. Our goal is to effectively serve this need by using bibliometric text mining and summarization techniques to generate summaries of scientific literature. We show how we can use citations to produce automatically generated, readily consumable, technical extractive summaries. We first propose C-LexRank, a model for summarizing single scientific articles based on citations, which employs community detection and extracts salient information-rich sentences. Next, we further extend our experiments to summarize a set of papers, which cover the same scienti fic topic. We generate extractive summaries of a set of Question Answering (QA) and Dependency Parsing (DP) papers, their abstracts, and their citation sentences and show that citations have unique information amenable to creating a summary.\",\n \"Title: Combining Outputs from Multiple Machine Translation Systems\\nYear: 2007\\n\\nAbstract: Currently there are several approaches to machine translation (MT) based on differ- ent paradigms; e.g., phrasal, hierarchical and syntax-based. These three approaches yield similar translation accuracy despite using fairly different levels of linguistic knowledge. The availability of such a variety of systems has led to a growing interest toward finding better translations by combining outputs from multiple sys- tems. This paper describes three differ- ent approaches to MT system combina- tion. These combination methods oper- ate on sentence, phrase and word level exploiting information from -best lists, system scores and target-to-source phrase alignments. The word-level combination provides the most robust gains but the best results on the development test sets (NIST MT05 and the newsgroup portion of GALE 2006 dry-run) were achieved by combining all three methods.\",\n \"Title: Deriving verbal and compositional lexical aspect for NLP applications\\nYear: 1997\\n\\nAbstract: Verbal and compositional lexical aspect provide the underlying temporal structure of events. Knowledge of lexical aspect, e.g., (a)telicity, is therefore required for interpreting event sequences in discourse (Dowty, 1986; Moens and Steedman, 1988; Passoneau, 1988), interfacing to temporal databases (Androutsopoulos, 1996), processing temporal modifiers (Antonisse, 1994), describing allowable alternations and their semantic effects (Resnik, 1996; Tenny, 1994), and selecting tense and lexical items for natural language generation ((Dorr and Olsen, 1996; Klavans and Chodorow, 1992), cf. (Slobin and Bocaz, 1988)). We show that it is possible to represent lexical aspect---both verbal and compositional---on a large scale, using Lexical Conceptual Structure (LCS) representations of verbs in the classes cataloged by Levin (1993). We show how proper consideration of these universal pieces of verb meaning may be used to refine lexical representations and derive a range of meanings from combinations of LCS representations. A single algorithm may therefore be used to determine lexical aspect classes and features at both verbal and sentence levels. Finally, we illustrate how knowledge of lexical aspect facilitates the interpretation of events in NLP applications.\",\n \"Title: Using paraphrases for parameter tuning in statistical machine translation\\nYear: 2007\\n\\nAbstract: Most state-of-the-art statistical machine translation systems use log-linear models, which are defined in terms of hypothesis features and weights for those features. It is standard to tune the feature weights in order to maximize a translation quality metric, using held-out test sentences and their corresponding reference translations. However, obtaining reference translations is expensive. In this paper, we introduce a new full-sentence paraphrase technique, based on English-to-English decoding with an MT system, and we demonstrate that the resulting paraphrases can be used to drastically reduce the number of human reference translations needed for parameter tuning, without a significant decrease in translation quality.\",\n \"Title: Inducing frame semantic verb classes from WordNet and LDOCE\\nYear: 2004\\n\\nAbstract: This paper presents SemFrame, a system that induces frame semantic verb classes from WordNet and LDOCE. Semantic frames are thought to have significant potential in resolving the paraphrase problem challenging many language-based applications.When compared to the handcrafted FrameNet, SemFrame achieves its best recall-precision balance with 83.2% recall (based on SemFrame's coverage of FrameNet frames) and 73.8% precision (based on SemFrame verbs' semantic relatedness to frame-evoking verbs). The next best performing semantic verb classes achieve 56.9% recall and 55.0% precision.\",\n \"Title: A Modality Lexicon and its use in Automatic Tagging\\nYear: 2010\\n\\nAbstract: This paper describes our resource-building results for an eight-week JHU Human Language Technology Center of Excellence Summer Camp for Applied Language Exploration (SCALE-2009) on Semantically-Informed Machine Translation. Specifically, we describe the construction of a modality annotation scheme, a modality lexicon, and two automated modality taggers that were built using the lexicon and annotation scheme. Our annotation scheme is based on identifying three components of modality: a trigger, a target and a holder. We describe how our modality lexicon was produced semi-automatically, expanding from an initial hand-selected list of modality trigger words and phrases. The resulting expanded modality lexicon is being made publicly available. We demonstrate that one tagger-a structure-based tagger-results in precision around 86% (depending on genre) for tagging of a standard LDC data set. In a machine translation application, using the structure-based tagger to annotate English modalities on an English-Urdu training corpus improved the translation quality score for Urdu by 0.3 Bleu points in the face of sparse training data.\",\n \"Title: Acquisition of bilingual MT lexicons from OCRed dictionaries.\\nYear: 2003\\n\\nAbstract: This paper describes an approach to analyzing the lexical structure of OCRed bilingual dictionaries to construct re- sources suited for machine translation of low-density languages, where online resources are limited. A rule-based, an HMM-based, and a post-processed HMM-based method are used for rapid construction of MT lexicons based on sys- tematic structural clues provided in the original dictionary. We evaluate the effectiveness of our techniques, concluding that: (1) the rule-based method performs better with dictionaries where the font is not an important distinguishing fea- ture for determining information types; (2) the post-processed stochastic method improves the results of the stochastic method for phrasal entries; and (3) Our resulting bilingual lexicons are comprehensive enough to provide the basis for reasonable translation results when compared to human translations.\",\n \"Title: Solving thematic divergences in machine translation\\nYear: 1990\\n\\nAbstract: Though most translation systems have some mechanism for translating certain types of divergent predicate-argument structures, they do not provide a general procedure that takes advantage of the relationship between lexical-semantic structure and syntactic structure. A divergent predicate-argument structure is one in which the predicate (e.g., the main verb) or its arguments (e.g., the subject and object) do not have the same syntactic ordering properties for both the source and target language. To account for such ordering differences, a machine translator must consider language-specific syntactic idiosyncrasies that distinguish a target language from a source language, while making use of lexical-semantic uniformities that tie the two languages together. This paper describes the mechanisms used by the UNITRAN machine translation system for mapping an underlying lexical-conceptual structure to a syntactic structure (and vice versa), and it shows how these mechanisms coupled with a set of general linking routines solve the problem of thematic divergence in machine translation.\",\n \"Title: Semantically-Informed Syntactic Machine Translation: A Tree-Grafting Approach.\\nYear: 2014\\n\\nAbstract: We describe a unified and coherent syntactic framework for supporting a semantically-informed syntactic approach to statistical machine translation. Semantically enriched syntactic tags assigned to the target-language training texts improved translation quality. The resulting system significantly outperformed a linguistically naive baseline model (Hiero), and reached the highest scores yet reported on the NIST 2009 Urdu-English translation task. This finding supports the hypothesis (posed by many researchers in the MT community, e.g., in DARPA GALE) that both syntactic and semantic information are critical for improving translation quality---and further demonstrates that large gains can be achieved for low-resource languages with different word order than English.\",\n \"Title: Use of Modality and Negation in Semantically-Informed Syntactic MT.\\nYear: 2015\\n\\nAbstract: This paper describes the resource- and system-building efforts of an eight-week Johns Hopkins University Human Language Technology Center of Excellence Summer Camp for Applied Language Exploration (SCALE-2009) on Semantically-Informed Machine Translation (SIMT). We describe a new modality/negation (MN) annotation scheme, the creation of a (publicly available) MN lexicon, and two automated MN taggers that we built using the annotation scheme and lexicon. Our annotation scheme isolates three components of modality and negation: a trigger (a word that conveys modality or negation), a target (an action associated with modality or negation) and a holder (an experiencer of modality). We describe how our MN lexicon was semi-automatically produced and we demonstrate that a structure-based MN tagger results in precision around 86% (depending on genre) for tagging of a standard LDC data set. We apply our MN annotation scheme to statistical machine translation using a syntactic framework that supports the inclusion of semantic annotations. Syntactic tags enriched with semantic annotations are assigned to parse trees in the target-language training texts through a process of tree grafting. While the focus of our work is modality and negation, the tree grafting procedure is general and supports other types of semantic information. We exploit this capability by including named entities, produced by a pre-existing tagger, in addition to the MN elements produced by the taggers described in this paper. The resulting system significantly outperformed a linguistically naive baseline model (Hiero), and reached the highest scores yet reported on the NIST 2009 Urdu-English test set. This finding supports the hypothesis that both syntactic and semantic information can improve translation quality.\",\n \"Title: Speech Adaptation In Extended Ambient Intelligence Environments\\nYear: 2015\\n\\nAbstract: This Blue Sky presentation focuses on a major shift toward a notion of \\\"ambient intelligence\\\" that transcends general applications targeted at the general population. The focus is on highly personalized agents that accommodate individual differences and changes over time. This notion of Extended Ambient Intelligence (EAI) concerns adaptation to a person's preferences and experiences, as well as changing capabilities, most notably in an environment where conversational engagement is central. An important step in moving this research forward is the accommodation of different degrees of cognitive capability (including speech processing) that may vary over time for a given user whether through improvement or through deterioration. We suggest that the application of divergence detection to speech patterns may enable adaptation to a speaker's increasing or decreasing level of speech impairment over time. Taking an adaptive approach toward technology development in this arena may be a first step toward empowering those with special needs so that they may live with a high quality of life. It also represents an important step toward a notion of ambient intelligence that is personalized beyond what can be achieved by mass-produced, one-size-fits-all software currently in use on mobile devices.\",\n \"Title: The NIST data science evaluation series: Part of the NIST information access division data science initiative\\nYear: 2015\\n\\nAbstract: The Information Access Division (IAD) of the National Institute of Standards and Technology (NIST) launched a new Data Science Initiative in the fall of 2015. This initiative focuses on evaluation-driven research and will establish a new Data Science Evaluation series to facilitate research collaboration, to leverage shared technology and infrastructure, and to further build and strengthen the data science community. The evaluation series will consist of a pre-pilot to be launched in the fall of 2015, a pilot evaluation to be launched in 2016, and a full-scale multiple-track evaluation in 2017. In addition to these evaluations, this new initiative aims to address several infrastructure challenges and to provide standards to encourage easier group collaboration.\",\n \"Title: Multiple Alternative Sentence Compressions and Word-Pair Antonymy for Automatic Text Summarization and Recognizing Textual Entailment\\nYear: 2008\\n\\nAbstract: Abstract The University of Maryland participated in three tasks organized by the Text Anal- ysis Conference 2008 (TAC 2008): (1) the update task of text summarization; (2) the opinion task of text summarization; and (3) recognizing textual entailment (RTE). At the heart of our summarization,sys- tem is Trimmer, which generates multi- ple alternative compressed,versions of the source sentences that act as candidate sen- tences for inclusion in the summary.,For the first time, we investigated the use of automatically generated antonym,pairs for both text summarization,and recognizing textual entailment. The UMD summaries for the opinion task were especially effec- tive in providing non-redundant informa- tion (rank 3 out of a total 19 submissions). More coherent summaries,resulted when using the antonymy,feature as compared to when not using it. On the RTE task, even when,using only automatically gen- erated antonyms,the system performed,as well as when,using a manually compiled list of antonyms.\",\n \"Title: Event Nugget Detection and Argument Extraction with DISCERN.\\nYear: 2016\\n\\nAbstract: This paper addresses the problem of detecting information about events from unstructured text. An event-detection system, DISCERN, is presented; its three variants DISCERN- R (rule-based), DISCERN-ML (machine-learned), and DISCERN-C (combined), were evaluated in the NIST TAC KBP 2015 Event Nugget Detection and Event Argument Extraction and Linking tasks. Three contributions of this work are: (a) an approach to collapsing support verb and event nominals that improved recall of argument linking, (b) a new linguist-in-the-loop paradigm that enables quick changes to linguistic rules and examination of their effect on pre- cision and recall at runtime, (c) an analysis of the synergy between the semantic and syntactic features. Results of experimentation with event-detection approaches indicate that linguistically-informed rules can improve precision and machine-learned systems can improve recall. Future refinements to the combination of linguistic and machine learning approaches may involve making better use of the complementarity of these approaches.\",\n \"Title: The NIST data science initiative\\nYear: 2015\\n\\nAbstract: We examine foundational issues in data science including current challenges, basic research questions, and expected advances, as the basis for a new Data Science Initiative and evaluation series, introduced by the National Institute of Standards and Technology (NIST) in the fall of 2015. The evaluations will facilitate research efforts, collaboration, leverage shared infrastructure, and effectively address cross-cutting challenges faced by diverse data science communities. The evaluations will have multiple research tracks championed by members of the data science community, and will enable rigorous comparison of approaches through common tasks, datasets, metrics, and shared research challenges. The tracks will measure several different data science technologies in a wide range of fields, starting with a pre-pilot. In addition to developing data science evaluation methods and metrics, it will address computing infrastructure, standards for an interoperability framework, and domain-specific examples.\",\n \"Title: Deterioration of Speech as an Indicator of Physiological Degeneration (DESIPHER).\\nYear: 2015\\n\\nAbstract: We approach the problem of understanding the disease progression and speech of patients suffering from ALS as a language divergence identification problem. We summarize the promises and challenges of using speech-related biomarkers to adapt speech recognition to ALS patients and correlate language divergence with disease progression.\",\n \"Title: A new data science research program: evaluation, metrology, standards, and community outreach.\\nYear: 2016\\n\\nAbstract: This article examines foundational issues in data science including current challenges, basic research questions, and expected advances, as the basis for a new data science research program (DSRP) and associated data science evaluation (DSE) series, introduced by the National Institute of Standards and Technology (NIST) in the fall of 2015. The DSRP is designed to facilitate and accelerate research progress in the field of data science and consists of four components: evaluation and metrology, standards, compute infrastructure, and community outreach. A key part of the evaluation and measurement component is the DSE. The DSE series aims to address logistical and evaluation design challenges while providing rigorous measurement methods and an emphasis on generalizability rather than domain- and application-specific approaches. Toward that end, each year the DSE will consist of multiple research tracks and will encourage the application of tasks that span these tracks. The evaluations are intended to facilitate research efforts and collaboration, leverage shared infrastructure, and effectively address crosscutting challenges faced by diverse data science communities. Multiple research tracks will be championed by members of the data science community with the goal of enabling rigorous comparison of approaches through common tasks, datasets, metrics, and shared research challenges. The tracks will permit us to measure several different data science technologies in a wide range of fields and will address computing infrastructure, standards for an interoperability framework, and domain-specific examples. This article also summarizes lessons learned from the data science evaluation series pre-pilot that was held in fall of 2015.\",\n \"Title: Ambient Personal Environment Experiment (APEX): A Cyber-Human Prosthesis for Mental, Physical and Age-Related Disabilities.\\nYear: 2015\\n\\nAbstract: We present an emerging research project in our laboratory to extend ambient intelligence (AmI) by what we refer to as “extreme personalization” meaning that an instance of ambient intelligence is focused on one or at most a few individuals over a very long period of time. Over a lifetime of co-activity, it senses and adapts to a person’s preferences and experiences, and crucially, his or her (changing) special needs; needs that differ significantly from the normal baseline. We refer to our agent-based cyber-physical system as Ambient Personal Environment eXperiment (APEX). It aims to serve as a Companion , a Coach , and a Caregiver : crucial support for individuals with mental, physical, and age-related disabilities and those other people who help them. We propose that an instance of APEX, interacting socially with each of these people, is both a social actor as well as a cyber-human prosthetic device . APEX is an ambitious integration of multiple technologies from Artificial Intelligence (AI) and other disciplines. Its successful development can be viewed as a grand challenge for AI. We discuss in this paper three research thrusts that lead toward our vision: robust intelligent agents, semantically rich human-machine interaction, and reasoning from comprehensive multi-modal behavior data.\",\n \"Title: Impact Of Filtering Generated Pseudo Bilingual Texts In Low-Resource Neural Machine Translation Enhancement: The Case Of Persian-Spanish\\nYear: 2021\\n\\nAbstract: Although the Neural Machine Translation (NMT) framework has already been shown effective in large training data scenarios, it is less effective for low-resource conditions. To improve NMT performance in a low-resource setting, we extend the high-quality training data by generating a pseudo bilingual dataset and then filtering out low-quality alignments using a quality estimation based on back-translation. We demonstrate that our approach yields significantly higher BLEU scores than those of a set of baselines. (C) 2021 The Authors. Published by Elsevier B.V.\",\n \"Title: From Stance to Concern: Adaptation of Propositional Analysis to New Tasks and Domains.\\nYear: 2022\\n\\nAbstract: We present a generalized paradigm for adaptation of propositional analysis (predicate-argument pairs) to new tasks and domains. We leverage an analogy between stances (belief-driven sentiment) and concerns (topical issues with moral dimensions/endorsements) to produce an explanatory representation. A key contribution is the combination of semi-automatic resource building for extraction of domain-dependent concern types (with 2-4 hours of human labor per domain) and an entirely automatic procedure for extraction of domain-independent moral dimensions and endorsement values. Prudent (automatic) selection of terms from propositional structures for lexical expansion (via semantic similarity) produces new moral dimension lexicons at three levels of granularity beyond a strong baseline lexicon. We develop a ground truth (GT) based on expert annotators and compare our concern detection output to GT, to yield 231% improvement in recall over baseline, with only a 10% loss in precision. F1 yields 66% improvement over baseline and 97.8% of human performance. Our lexically based approach yields large savings over approaches that employ costly human labor and model building. We provide to the community a newly expanded moral dimension/value lexicon, annotation guidelines, and GT.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":76,"string":"76"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":276,"string":"276"}}},{"rowIdx":277,"cells":{"question_id":{"kind":"string","value":"Qi Lu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Multi-Cycle Measuring and Data Fusion for Large End Face Run-Out of Tapered Roller\" using the following items: 1. End face run-out\n2. Tapered roller\n3. Auto-measuring equipment\n4. Data processing software\n5. Chinese patent"},"answer":{"kind":"string","value":"The large end face run-out is a kind of shape and position tolerance, and is an important index in deciding the class of the tapered roller. The auto-measuring and sorting equipments for the tapered roller introduced in this article is an intelligent measuring equipment that orientates in pursuing measurement and choosing of every tapered roller on grinding spot. According to professional standard about the tapered roller, the large end face run-out (notated as SDW) must be measured dynamically during revolving on normal V-shape table. In order to eliminate the disturbance caused by electromagnetism interference and machine vibration, this equipment adopts multi-cycle measuring under single sensor, making better use of the regeneration of the sampling signal and based on analysis of the main factors leading to the large end face run-out and signal characteristics. On the other hand, two kinds of signal-characteristics-based data association threshold filtering algorithm and an improved weight arithmetic mean data fusion algorithm are applied on data processing software embedded in it. This equipment has been proved by practical application and has obtained a Chinese patent."},"correct_answer":{"kind":"string","value":"The large end face run-out is a kind of shape and position tolerance, and is an important index in deciding the class of the tapered roller. The auto-measuring and sorting equipments for the tapered roller introduced in this article is an intelligent measuring equipment that orientates in pursuing measurement and choosing of every tapered roller on grinding spot. According to professional standard about the tapered roller, the large end face run-out (notated as SDW) must be measured dynamically during revolving on normal V-shape table. In order to eliminate the disturbance caused by electromagnetism interference and machine vibration, this equipment adopts multi-cycle measuring under single sensor, making better use of the regeneration of the sampling signal and based on analysis of the main factors leading to the large end face run-out and signal characteristics. On the other hand, two kinds of signal-characteristics-based data association threshold filtering algorithm and an improved weight arithmetic mean data fusion algorithm are applied on data processing software embedded in it. This equipment has been proved by practical application and has obtained a Chinese patent."},"documents":{"kind":"list like","value":["Title: Efficient Large-Scale Access Control for Internet/Intranet Information Systems\nYear: 1999\n\nAbstract: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099. Access control is a key problem for information processing, especially in a distributed environment such as the Internet and Intranet, where diverse information resources will be made available for \"diverse\" users to query. We present an efficient method for large scale access control problem. It main ingredient is a representation of hierarchical access group structures as intervals over integers and a decomposition scheme that reduces any group structure to ones that have interval representations. This representation allows the problem for checking access rights to be reduced to an interval containment problem.","Title: Performance analysis for optical wireless communication systems using subcarrier PSK intensity modulation through turbulent atmospheric channel.\nYear: 2004\n\nAbstract: This paper compares the performance of on-off keying (OOK) modulation and subcarrier phase shift keying (PSK) modulation through optical wireless channel. The bit error rate (BER) for turbulence channel is derived for optical wireless communication systems employing OOK or subcarrier BPSK. A lower bound is derived for BER performance when fixed-threshold OOK is used. It is also shown that the BER performance of the optical wireless communication system employing subcarrier PSK modulation is more than 3 dB better than that of a compatible system employing fixed-threshold OOK modulation at BER = 10(-6) and with turbulence parameter sigma = 0.1. When sigma is 0.2 and fixed-threshold OOK is: employed, the BER performance never falls down to 10(-4). The BER performance degradation of optical wireless communication systems employing subcarrier BPSK between sigma = 0.1 and sigma = 0.2 is only 2.5 dB at BER = 10(-6).","Title: Developing a novel full-polarimetric GPR technology\nYear: 2011\n\nAbstract: Generally GPR transmits and receives radio waves with a single polarization using two parallel antennas. But it is possible to improve the GPR ability of discrimination and imaging of subsurface targets by analyzing the backscattered wave with a variety of polarizations. So we are developing a full-polarimetric GPR system, including PC, network analyzer, rectangular coordinates robot, switch driver, and polarimetric antenna array. Polarimetric antenna array is used to transmit and receive both co-polarimetric and cross-polarimetric signals. Currently polarimetric GPR do not execute precise calibration. But good calibration can improve the classification ability of subsurface targets. So we introduced the calibration technique into the polarimetric GPR, and derived a calibration formula.","Title: Developing calibration technology for full-polarimetric GPR\nYear: 2012\n\nAbstract: Polarimetric GPR requires accurate calibration of channel imbalance and crosstalk not only in the amplitude term but also in the phase term. Currently, there have some calibration techniques. Though these techniques are very easy to perform, they provide less accurate calibration results for the crosstalk. To improve on the accuracy of calibration, we have developed a mathematical formulation to calibrate polarimetric GPR data. We measured several scattering matrices to obtain the necessary calibration parameters. The calibration technique was tested from measurements conducted on dihedral corner reflector.","Title: 3D velocity model and ray tracing of antenna array GPR\nYear: 2010\n\nAbstract: Migration is an important signal processing method that can improve signal-clutter ratio and reconstruct subsurface image. Diffraction stacking migration and Kirchhoff migration sum amplitudes along the migration trajectory, which generally is hyperbolic. But when the ground surface varies acutely, the migration trajectory is not hyperbolic. To computer the migration trajectory need the technique of ray tracing. We introduce a method of ray tracing based on 3D velocity model. Firstly, we build the 3D velocity model depending on the estimation of both ground surface topography and velocities. Then we compute the travel time between transmitter, receiver and each subsurface scattering point, and search the propagation ray depending on the Fermat's principle. The method is tested by an experiment data acquired by the stepped-frequency (SF) CMP antenna GPR system. The target is a metal ball that is buried under a sand mound. A nice result of ray tracing is shown in the case.","Title: Organizing the digital world to empower people to do more, know more, and be more\nYear: 2014\n\nAbstract: The web is rapidly evolving into the web of the world where people, places, things and their relationships are all digitally represented. This evolution opens up unparalleled opportunities to organize this vast digital universe for even greater human purpose. In this talk, Dr. Lu will share an outline of Microsoft's quest and aspiration to organize the digital universe with a pervasive computational fabric of digital information, digital services, and digital experiences that empower every human being on the planet to accomplish more and enrich their life. Dr. Lu will discuss high level computational structures and present specific examples across Bing, Windows and other products and services to illustrate Microsoft's approach to delivering end user value and accelerating the pace of innovation for the industry as a whole.","Title: Carleman Estimate For Stochastic Parabolic Equations And Inverse Stochastic Parabolic Problems\nYear: 2011\n\nAbstract: In this paper, we establish a global Carleman estimate for stochastic parabolic equations. Based on this estimate, we study two inverse problems for stochastic parabolic equations. One is concerned with a determination problem of the history of a stochastic heat process through the observation at the final time T for which we obtain a conditional stability estimate. The other is an inverse source problem with observation on the lateral boundary. We derive the uniqueness of the source.","Title: Subsurface imaging by modified migration for irregular GPR data\nYear: 2012\n\nAbstract: Handheld ground-penetrating radar (GPR) system is one of a number of technologies that has been researched as a means of improving landmine detection efficiency. However, as the measurement points are random and data are irregular for the human operator, it is difficult to display subsurface visualization imaging. Also detection of buried landmines by GPR normally suffers from very strong clutter that will decrease the image quality. To solve the problem, a modified migration algorithm was proposed to process irregular GPR data, which has both the advantage of migration that can improve signal-clutter ratio and the advantage of interpolation that produces the grid data set for visualization. An application to field data acquired in Afghanistan shows clear landmine image in both vertical profile and horizontal slice.","Title: Parallel Profile Matching for Large Scale Webcasting\nYear: 1998\n\nAbstract: Profile matching is a key problem for webcasting systems. In such a system, each user has a personal profile. Each information document is matched with profiles in a profile-database, and pushed only to those users whose profiles match the content of the document. We present an efficient and scalable parallel profile matching algorithm which can handle a large subscription volume and diversity of information content. Our algorithm automatically partitions the profile database for load balancing and minimizes the interaction among processors in parallel profile matching. It has a dynamic load balancing mechanism for handling profile updates. We describe the implementation of our algorithm in the context of the Grand Central Station (GCS) project at the IBM Almaden Research Center. The initial performance evaluation indicates that parallel profile matching can be scaled up gracefully via dynamic adaptation.","Title: Fractal Curve and Attribute Grammar\nYear: 1988\n\nAbstract: Without Abstract","Title: Group mobility support in mobile WiMAX networks\nYear: 2011\n\nAbstract: Group mobility refers to the scenarios that multiple mobile stations (MSs) move in a group at the same time, generally in the same direction with a short distance of separation. In the normal operation, when the group of MSs moves out of the coverage of the current serving BS and into that of another BS, multiple handovers processes should be performed at almost the same time. Large latency will be incurred due to the collisions of the ranging requests from the MSs in the group and the extra time for the corresponding backoff. Especially, when the number of MSs in the group is larger, the handover latency becomes much more significant and it would affect transmissions seriously. In this paper, we propose a group handover scheme to design an efficient and effective handover process with low latency for the group mobility scenarios in the mobile WiMAX networks. The Bridge MS is introduced to integrate several handover processes for the group of MSs into only one, which could eliminate the collision of the ranging requests and shorten the latency incurred. The results of the evaluation show that much lower handover latency for the group of MSs during the handover could be obtained by the proposed scheme and the improvement becomes significant as the number of MSs is increased in the group.","Title: Achieving Faster Handovers in Mobile WiMAX Networks\nYear: 2012\n\nAbstract: WiMAX is a wireless metropolitan area network (WMAN) specified by IEEE 802.16. It provides the broadband wireless access for mobile devices. In such a system, to enable the mobility, the handover is supported to maintain the connectivity of the mobile station (MS) when it moves from the coverage of the serving base station (BS) to the coverage of a neighbor BS. In the handover process, scanning is required to find a suitable target BS, and network re-entry is needed to establish the new connection. However, in the standard handover process, a long latency to data transmissions is caused resulting in the serious interruption to ongoing services. In this paper, an improved handover scheme is proposed to reduce the latency introduced in the handover process by shortening the scanning and enhancing the network re-entry. The proposed scanning strategy reduces the latency by reducing the number of neighbor BSs to be scanned through estimating the rough location of the MS. The enhanced network re-entry reduces the delay by updating transport connection identifiers (CIDs) early to allow the fast resumption of active applications. Simulations were conducted to evaluate the performance of the proposed handover scheme. The results show that the proposed handover scheme reduces the data transmission latency during handover significantly.","Title: Collaborative Web Crawling: Information Gathering/Processing over Internet\nYear: 1999\n\nAbstract: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099. In this paper, we present a scalable method for collaborative web crawling and information processing. The method includes an automatic cyberspace partitioner which is designed to dynamically balance and re-balance the load among processors. It can be can be used when all web crawlers are located on a tightly coupled high-performance system as well as when they are scattered in a distributed environment. We have implemented our algorithms in Java as a part of the IBM Grand Central Station (GCS) system.","Title: Improving data consistency in mobile computing using isolation-only transactions\nYear: 1995\n\nAbstract: Disconnected operation is an important technique for providing mobile access to shared data in distributed file systems. However, data inconsistency resulting from partitioned sharing remains a serious concern. This paper presents a new mechanism called isolation-only transaction (IOT) that uses serializability constraints to automatically detect read/write conflicts. The IOT consistency model provides a set of options for automatic and manual conflict resolution. In addition, application-specific knowledge can be incorporated to detect and resolve conflicts. To preserve upward Unix compatibility, the IOT mechanism is provided as an optional file system facility and its flexible interfaces allow any existing Unix application to be executed as an IOT. This paper describes high-level system design and implementation and concludes with related work and current status","Title: Performance of Phase Modulated Systems Using Fully Saturated Power Amplifiers\nYear: 2004\n\nAbstract: This paper studies the performances of BPSK and QPSK modulations amplified by fully saturated power amplifiers. To achieve better performance, both convolutional code and Turbo code are used. Viterbi decoding and iterative turbo decoding are employed in the receiver, respectively. Simulation results show that good BER performance can be achieved when signal is amplified by fully saturated power amplifiers and transmitted through AWGN channel. The SNR degradation is 0.7 dB for BPSK and 0.3-0.4 dB for QPSK at BER= 10(-5).","Title: Singularity Analysis Of Planar Cable-Driven Parallel Robots\nYear: 2008\n\nAbstract: It is well known that parallel robots may have singular configurations that can result in a loss of full control the mechanisms. This paper analyzes two different categories of singularities of planar cable-driven parallel robots with four or more cables. The unidirectional constraint of cables makes the singularity analysis of cable-driven parallel robots different from that of rigid-link parallel robots even if they have similar kinematical architectures. Based on their natures, singularities of cable-driven parallel robots are classified into two categories: the Jacobian singularity and the force-closure singularity. A Jacobian singularity occurs when the Jacobian matrix of a cable-driven parallel robot loses its full rank. Based on rank analysis of Jacobian matrix, a group of Jacobian singularities is reported with mathematical proof. When the Jacobian matrix of a cable-driven parallel robot has a full rank, the cables' inability to generate tension will lead to force-closure singularities, which can always happen to fully-constrained cable-driven parallel robots. An algorithm of identifying force-closure singularities of planar cable-driven parallel robots is proposed. Understanding of the natures of singularities is important for the design and control of cable-driven parallel robots.","Title: Future of the web and search\nYear: 2011\n\nAbstract: No one doubts that we have only scratched the surface of what is possible with the Web. The day is coming fast when the Web will become almost a virtual mind reader. Your intent, interests, and needs will be instantly perceived and the information you want will be promptly delivered -- whether you ask for it directly or not -- based on a deep understanding of the meaning of words in your query, knowledge of your preferences and patterns, what others have done before you, your location, and more. In this talk, I will share some of my thoughts about where the Web is heading and how search will be transformed to align to this new Web, laying out some specifics behind Microsoft's vision to empower people with knowledge.","Title: BigDL: A Distributed Deep Learning Framework for Big Data.\nYear: 2018\n\nAbstract: ThispaperpresentsBigDL (adistributeddeeplearning framework for Apache Spark), which has been used by a variety of users in the industry for building deep learning applications on production big data platforms. It allows deep learning applications to run on the Apache Hadoop/Spark cluster so as to directly process the production data, and as a part of the end-to-end data analysis pipeline for deployment and management. Unlike existing deep learning frameworks, BigDL implements distributed, data parallel training directly on top of the functional compute model (with copy-on-write and coarse-grained operations) of Spark. We also share real-world experience and \"war stories\" of users that havead-optedBigDLtoaddresstheirchallenges(i.e., howtoeasilybuildend-to-enddataanalysisanddeep learning pipelines for their production data).","Title: Reachability analysis for timed automata using max-plus algebra.\nYear: 2012\n\nAbstract: We show that max-plus polyhedra are usable as a data structure in reachability analysis of timed automata. Drawing inspiration from the extensive work that has been done on difference bound matrices, as well as previous work on max-plus polyhedra in other areas, we develop the algorithms needed to perform forward and backward reachability analysis using max-plus polyhedra. To show that the approach works in practice and theory alike, we have created a proof-of-concept implementation on top of the model checker opaal.","Title: Resource conservation in a mobile transaction system\nYear: 1997\n\nAbstract: This paper addresses the problem of providing transactional support for improved data consistency in mobile file access, while paying careful attention to the resource constraints of mobile clients. We present data on resource consumption from an implementation of the isolation-only transaction (IOT) mechanism of the Coda File System. The data shows that the resource conservation techniques used by the IOT mechanism do indeed result in modest demands on the three critical resources on a mobile client: CPU and I/O usage, disk space, and RVM space. Overall, our measurements confirm that even a severely resource-constrained mobile client can benefit from the improved consistency offered by the IOT mechanism","Title: Boosting for Multi-Modal Music Emotion Classification.\nYear: 2010\n\nAbstract: With the explosive growth of music recordings, automatic classification of music emotion becomes one of the hot spots on research and engineering. Typical music emotion classification (MEC) approaches apply machine learning methods to train a classifier based on audio features. In addition to audio features, the MIDI and lyrics features of music also contain useful semantic information for predicting the emotion of music. In this paper we apply AdaBoost algorithm to integrate MIDI, audio and lyrics information and propose a two-layer classifying strategy called Fusion by Subtask Merging for 4-class music emotion classification. We evaluate each modality respectively using SVM, and then combine any two of the three modalities, using AdaBoost algorithm (MIDI+audio, MIDI+lyrics, audio+lyrics). Moreover, integrating this in a multimodal system (MIDI+audio+lyrics) allows an improvement in the overall performance. The experimental results show that MIDI, audio and lyrics information are complementary, and can be combined to improve a classification system. © 2010 International Society for Music Information Retrieval.","Title: Experience with Disconnected Operation in a Mobile Computing Environment\nYear: 1994\n\nAbstract: In this paper we present qualitative and quantitative data on file access in a mobile computing environment. This information is based on actual usage experience with the Coda File System over a period of about two years. Our experience confirms the viability and effectiveness of disconnected operation. It also exposes certain deficiencies of the current implementation of Coda, and identifies new functionality that would enhance its usefulness for mobile computing. The paper concludes with a description of what we are doing to address these issues.","Title: A New Scheme to Mitigate the OFDM High PAR Problem by Minimizing the Signal's Nonlinear Distortion Caused by HPA\nYear: 2006\n\nAbstract: How to mitigate the negative impact of high PAR in OFDM systems is an important issue. Most of recent works have focused on minimizing the PAR of OFDM signal to enhance performance. However, after relating this issue with the specific characteristics of HPA, we propose a new scheme to mitigate the high PAR problem. Rather than minimizing OFDM signal's PAR, the new scheme uses the amount of OFDM signal's nonlinear distortion to be caused by HPA as a new measure and increases the performance of OFDM system by minimizing this nonlinear distortion. The pre-calculation of the new measure is achieved by employing an adaptive nonlinear system identification process. Meanwhile, because the new scheme only changes the measure of the OFDM signal but not the frameworks of the prior PAR-reduction methods based on minimum PAR criterion, these prior PAR-reduction methods can be easily extended to incorporate the new scheme. A case study of the new scheme by adopting it in the SLM method shows its superiority over the conventional scheme","Title: Efficient profile matching for large scale Webcasting\nYear: 1998\n\nAbstract: This paper presents an efficient method of matching diverse data against user profiles in large-scale Webcasting systems. Its design and implementation are described in the context of the Grand Central Station (GCS) project at IBM Almaden Research Center. Initial performance evaluation indicates the ability of GCS profile matching to scale up and achieve strong performance via dynamic adaptation.","Title: Geometric quantifier elimination heuristics for automatically generating octagonal and max-plus invariants\nYear: 2013\n\nAbstract: Geometric heuristics for the quantifier elimination approach presented by Kapur (2004) are investigated to automatically derive loop invariants expressing weakly relational numerical properties (such as l≤x≤h or l≤±x ±y≤h) for imperative programs. Such properties have been successfully used to analyze commercial software consisting of hundreds of thousands of lines of code (using for example, the Astrée tool based on abstract interpretation framework proposed by Cousot and his group). The main attraction of the proposed approach is its much lower complexity in contrast to the abstract interpretation approach (O(n2) in contrast to O(n4), where n is the number of variables) with the ability to still generate invariants of comparable strength. This approach has been generalized to consider disjunctive invariants of the similar form, expressed using maximum function (such as max (x+a,y+b,z+c,d)≤max (x+e,y+f,z+g,h)), thus enabling automatic generation of a subclass of disjunctive invariants for imperative programs as well.","Title: Isolation-only transactions for mobile computing\nYear: 1994\n\nAbstract: 1. Motivation The Unix File System(UFS) has historically offered a shared-memory consistency model. The lack of concurrency control makes this model susceptible to read/write conflicts, i.e., unexpected read/write sharing between two different processes. For example, the update of a header file by one user while another user is performing a long-runningmake can cause inconsistencies in the compilation results. In practice, read/write conflicts are rare for two reasons. First, the window of vulnerability is relatively small because read/write conflicts only occur when the executions of two processes overlap. Second, they are often prevented via explicit user-level coordination. However, the advent of mobile computing makes read/write conflicts a realistic threat to data integrity. Mobile computing is characterized by periods of disconnection and intermittent connectivity(11). Such communication disturbances greatly widen the window of vulnerability from the life span of a process to the duration of a disconnection. They also significantly reduce the effectiveness of explicit user-level coordination, especially when disconnections are made transparent to users. How can we preserve upward compatibility with the large body of existing Unix software, while offering improved consistency in a mobile computing environment? This position paper puts forth our solution, a new transaction model called isolation only transaction (IOT).","Title: Data mining in the online services industry\nYear: 2010\n\nAbstract: The online services industry is a rapidly growing industry with a worldwide online ad market projected to grow from $48 billion in 2011 to $67 billion in 2013, of which 47% will come from display advertising and 53% from search advertising. Online Services Division (OSD) within Microsoft is a leader in the consumer cloud space today with a strong portfolio of a set of 3 mutually reinforcing businesses: Search, Portal, Advertising. They are supported by a shared foundational asset of Intent & Knowledge Stores and a shared technology platform supporting large scale data and high performance systems. MSN (Portal) and Bing (Search) generate the content, traffic and data, that make for an exciting fertile environment for large scale data mining practice and system development. Our advertisers are thus given more valuable targeting opportunities and better ROI, which in turn, provide better economics, usability data, and allows for a higher quality services for our advertisers and experience for our users. The ability to transform data into meaningful, actionable insight is an important source of competitive advantage for OSD. The data mining initiatives within the division continue to strive for excellence around the following goals: actionable insights through deep data analysis, data mining and data modeling at scale and with speed, increased productivity from deployed large scale data systems and tools, improved product and service development and decision making gained from effective measurement and experimentation, and a mature data culture in product teams that made the above possible. With many technical and data challenges ahead of us, we are committed to utilizing our huge data asset well to understand the need, intent, and behavior of our users for the purpose of serving them better.","Title: Design, Proof and Analysis of New Efficient Algorithms for Incremental Attribute Evaluation\nYear: 1988\n\nAbstract: Without Abstract","Title: Calibration with high-order terms of polarimetric GPR\nYear: 2012\n\nAbstract: To provide meaningful data, polarimetric ground penetrating radar (GPR) requires accurate calibration of channel imbalance and crosstalk not only in the amplitude term but also in the phase term. Currently, calibration techniques usually ignore higher-order terms to simplify equations. These techniques, though very easy to perform, provide less accurate calibration results for the crosstalk. To im...","Title: Modeling of forced convection heat transfer from the swing plate on an industrial robot\nYear: 2014\n\nAbstract: The swing plate on an industrial robot is a sort of disk-like component through which an amount of heat generated inside the robot axis 1 drivetrain will transfer to the ambient. This raises a need on modeling and design of the swing plate from a thermal perspective. However, it still remains questionable whether or not the thermal models developed for conventional type of rotating disks are applicable to the swing plate on a robot. This is because, not like the conventional spinning disk which rotates in a single direction continuously, the swing plate is driven back-and-forth in a bi-directional mode, called rotary reciprocation. This paper aims to understand the convection heat transfer properties of such a swing plate by conducting a set of experiments with a plate undergoing rotary reciprocation. A set of empirical models are then assessed by comparing against the experimental results, and eventually, the model that best describes forced convection of the swing plate is obtained.","Title: Ground water migration monitoring by GPR\nYear: 2002\n\nAbstract: In order to understand the capability of monitoring ground water movement by ground penetrating radar (GPR), we carried out a field survey in Mongolia. We controlled water production at a ground water source area and the change of ground water level at about 5 m in depth could be detected by GPR. The change of the ground water level was observed more than 15 m in the radial distance from the pumping well. The change of the vertical water content was also evaluated by GPR.","Title: Model-Based Temperature Estimation Methods In Design Of Industrial Manipulator And Their Assessment\nYear: 2015\n\nAbstract: Estimation of the steady state temperature rise of an industrial manipulator and its key components is often desired in the design of a manipulator. This paper presents and compares three model-based methods which aim to achieve the temperature estimation in early design phase before prototype test. The basic idea of each method is introduced along with the results of corresponding experimental verifications. The verifications basically demonstrates the feasibility of the methods. The accuracy of the temperature estimation by all three methods is acceptable for use in early design phase. A brief assessment of the methods is also presented which should be helpful for users to select the most suitable method in design practice.","Title: Freeway ramp metering based on genetic algorithm optimization\nYear: 2015\n\nAbstract: Contraposing the complexity of a ramp control problem, we propose a method of proportional plus integral (PI) control and genetic algorithm optimization for ramp metering in this paper. Firstly, we build a cell transmission model (CTM) for freeway traffic. After that, we design several ramp controllers based upon CTM and feedback control method, and give the optimization process of a genetic algorithm in detail for optimizing the PI parameters. Finally, we simulate the ramp controllers by computer. Simulation reveals that the ramp metering controllers based on genetic algorithm optimization are of good performance. This control method can stabilize traffic flow as well as improve traffic situations.","Title: Cross-region traffic prediction for China on OpenStreetMap.\nYear: 2016\n\nAbstract: OpenStreetMap (OSM) is a free, open-source and popular mapping service. However, due to various reasons, it doesn't offer live traffic information or traffic prediction for China. This paper presents an approach and a system to learn a prediction model from graphical traffic condition data provided by Baidu Map, which is a commercial, close-source map provider in China, and apply the model on OSM so that one can predict the traffic conditions with nearly 90% accuracy in various parts of Shanghai, China, even though no traffic data is available for that area from Baidu Map. This novel system can be useful in urban planning, transportation dispatching as well as personal travel planning.","Title: Optimizing Propagation Network of Certificate Revocation in VANET with Meet-Table.\nYear: 2016\n\nAbstract: Certificate is widely used in VANET (Vehicle Ad hoc Network) to make it secure. But when a certificate is untrustworthy, it must be revoked. Propagation of certificate revocation information in VANET is not only essential but also challenging. In order to optimizing the propagation network of certificate revocation, Meet-Table is proposed. The Meet-Table of a vehicle records vehicles it met in the past. With the help of Meet-Table, a vehicle only needs to broadcast CRL (Certificate Revocation List) related to vehicles in its Meet-Table, so the network communication complexity and storage complexity of CRL in VANET can be optimized. Both of the two complexities are discussing formally. Comparing the schema proposed in this paper with CRL in classical PKI, road side unit broadcasting and epidemic fashion shows that the Meet-Table can significantly reduce the complexity of CRL propagation.","Title: A Scalable and Adaptable Multiple-Place Foraging Algorithm for Ant-Inspired Robot Swarms.\nYear: 2016\n\nAbstract: Individual robots are not effective at exploring large unmapped areas. An alternate approach is to use a swarm of simple robots that work together, rather than a single highly capable robot. The central-place foraging algorithm (CPFA) is effective for coordinating robot swarm search and collection tasks. Robots start at a centrally placed location (nest), explore potential targets in the area without global localization or central control, and return the targets to the nest. The scalability of the CPFA is limited because large numbers of robots produce more inter-robot collisions and large search areas result in substantial travel costs. We address these problems with the multiple-place foraging algorithm (MPFA), which uses multiple nests distributed throughout the search area. Robots start from a randomly assigned home nest but return to the closest nest with found targets. We simulate the foraging behavior of robot swarms in the robot simulator ARGoS and employ a genetic algorithm to discover different optimized foraging strategies as swarm sizes and the number of targets are scaled up. In our experiments, the MPFA always produces higher foraging rates, fewer collisions, and lower travel and search time compared to the CPFA for the partially clustered targets distribution. The main contribution of this paper is that we systematically quantify the advantages of the MPFA (reduced travel time and collisions), the potential disadvantages (less communication among robots), and the ability of a genetic algorithm to tune MPFA parameters to mitigate search inefficiency due to less communication.","Title: Acoustic holography — A robot application\nYear: 2016\n\nAbstract: Acoustic holography is a technique to visualize the sound field propagating from a sound source. It is used to analyse and locate sources of noise, and even allows to predict the propagation of sound in the environment. However, this technique involves simultaneous measurements of up to 256 microphones, arranged in an array. We propose an alternative approach with 4 or less microphones which are re-positioned using an articulated robot arm. Provided the measurement conditions are stable, this alternative approach with consecutive measurements allows to make use of acoustic holography to investigate various sources of noise. The case of fan noise is demonstrated where the focus is put on practical aspects conducting near-field acoustic holography experiments using a robot arm, as well as post-processing measurement data. As a result, 2 complimenting techniques, static and dynamic near-field acoustic holography, are introduced and their merits are discussed.","Title: Research On Data Mining Service And Its Application Case In Complex Industrial Process\nYear: 2017\n\nAbstract: In today's competitive market, companies need to apply different data mining techniques in order to make more intelligent, accurate business decisions. Data mining technology from industrial big data can provide a more effective help for decision-making of enterprises' innovative design. This paper explores the advantages of data mining services, and presents a SOA-based data mining framework applied to non-expert data miners which can be treated as Software-as-a-Service including data uploading, data cleaning, data mining algorithm, OLAP and so on. As an example, a hybrid reasoning mechanism for intelligent design decision based on DM and its application in complex textile industry are also discussed.","Title: Exploring the potential climate change impact on urban growth in London by a cellular automata-based Markov chain model.\nYear: 2018\n\nAbstract: Urbanization has become a global trend under the combined influence of population growth, socioeconomic development, and globalization. Even though recent urban planning in London has been more deliberate, the relationships between climate change and urban growth in the context of economic geography are still somewhat unclear. This study relies on rainfall prediction with the aid of the Statistical DownScaling Model (SDSM), which provides the statistical foundation for future flooding potential within the urban space of London while considering major socioeconomic policies related to land use management. These SDSM findings, along with current land use policies, were included as other factors or constraints in a cellular automata-based Markov Chain model to simulate and predict land use changes in London for 2030 and 2050. Two scenarios with the inclusion and exclusion of flood impact factor, respectively, were applied to evaluate the impact of climate change on urban growth. Findings indicated: (1) mean monthly projected precipitation derived by SDSM is expected to increase for the year 2030 in London, which will affect the flooding potential and hence the area of open space; (2) urban and open space are expected to increase >16 and 20km2 (in percentage of 1.51 and 1.92 compared to 2012) in 2030 and 2050, respectively, while agriculture is expected to decrease significantly due to urbanization and climate change; (3) the inclusion of potential flood impact induced from the future precipitation variability drives the development toward more open space and less urban area.","Title: Feature-Based Carbon Emission Quantitation Strategy For The Part Machining Process\nYear: 2018\n\nAbstract: As global warming is becoming remarkably serious, the issue of low-carbon manufacturing has attracted numerous researchers' attention. Meanwhile, manufacturing industries require the carbon emission data of their products to cope with the coming carbon policy such as carbon labelling. Since products are made of parts, one of the major difficulties is the lack of a well-established approach to obtain the carbon emissions of machining a part. In this paper, a carbon emission quantitation strategy is proposed to quantify the overall carbon emissions of a part machining process. In the quantitation strategy, firstly, the calculation models for various types of carbon emissions are presented to analyse the carbon footprint. A formalised approach is then proposed to quantify the overall carbon emissions by designing a c-PBOM (carbon emissions-Process Bill of Material) based on machining features. Particularly, in order to reduce the computation complexity and clarify the computation process, a c-PBOM is established to support the quantitation strategy by decomposing a part into an aggregation of machining features. In addition, the machining process is considered as a cooperation of the energy consumers decomposed from the machine tool. Finally, the strategy is applied in the machining of a bearing seat. The results show it can be used to predict the carbon emissions for a part machining process conveniently and efficiently, which would provide a data base for the research of low-carbon process planning and scheduling.","Title: Application of Time-Domain Full Waveform Inversion to Cross-Hole Radar Data Measured at Xiuyan Jade Mine, China.\nYear: 2018\n\nAbstract: Xiuyan Jade, produced in Xiuyan County, Liaoning Province, China is one of the four famous jade in China. King Jade, which is deemed the largest jade body of the world, was broken out from a hill. The local government planned to build a tourism site based on the jade culture there. The purpose of the investigation was to evaluate the stability of subsurface foundation, and the possible positions of mined-out zones to prevent the further rolling of the jade body. Cross-hole radar tomography is the key technique in the investigation. Conventional travel time and attenuation tomography based on ray tracing theory cannot provide high-resolution images because only a fraction of the measured information is used in the inversion. Full-waveform inversion (FWI) can provide high-resolution permittivity and conductivity images because it utilizes all the information provided by the radar signals. We deduce the gradient expression of the time-domain FWI with respect to the permittivity and conductivity using a method that is different from that of the previous work and realize the FWI algorithm that can simultaneously update the permittivity and conductivity by using the conjugate gradient method. Inverted results from synthetic data show that time-domain FWI can significantly improve the resolution compared with the ray-based tomogram methods. FWI can distinguish targets that are as small as one-half to one-third wavelength and the inverted physical values are closer to the real ones than those provided by the ray tracing method. We use the FWI algorithm to the field data measured at Xiuyan jade mine. Both the inverted permittivity and conductivity can comparably delineate four mined-out zones, which exhibit low-permittivity and low-conductivity characteristics. Furthermore, the locations of the interpreted mined-out zones are in good agreement with the existing mining channels recorded by geological data.","Title: Sequential Context Encoding for Duplicate Removal.\nYear: 2018\n\nAbstract: Duplicate removal is a critical step to accomplish a reasonable amount of predictions in prevalent proposal-based object detection frameworks. Albeit simple and effective, most previous algorithms utilize a greedy process without making sufficient use of properties of input data. In this work, we design a new two-stage framework to effectively select the appropriate proposal candidate for each object. The first stage suppresses most of easy negative object proposals, while the second stage selects true positives in the reduced proposal set. These two stages share the same network structure, i.e., an encoder and a decoder formed as recurrent neural networks (RNN) with global attention and context gate. The encoder scans proposal candidates in a sequential manner to capture the global context information, which is then fed to the decoder to extract optimal proposals. In our extensive experiments, the proposed method outperforms other alternatives by a large margin.","Title: A Kinect-Based Approach for 3D Pavement Surface Reconstruction and Cracking Recognition.\nYear: 2018\n\nAbstract: Pavement surface distress conditions are critical inputs for quantifying roadway infrastructure serviceability. Numerous computer-aided automatic examination techniques have been deployed for pavement distress condition assessments, such as digital image processing methods. However, their effectiveness and applicability are impeded due to information losses in 2-D image combination processes or ex...","Title: Graph-Based Knowledge Reuse For Supporting Knowledge-Driven Decision-Making In New Product Development\nYear: 2017\n\nAbstract: Pre-existing knowledge buried in manufacturing enterprises can be reused to help decision-makers develop good judgements to make decisions about the problems in new product development, which in turn speeds up and improves the quality of product innovation. This paper presents a graph-based approach to knowledge reuse for supporting knowledge-driven decision-making in new product development. The paper first illustrates the iterative process of knowledge-driven decision-making in new product development. Then, a novel framework is proposed to facilitate this process, where knowledge maps and knowledge navigation are involved. Here, OWL ontologies are employed to construct knowledge maps, which appropriately capture and organise knowledge resources generated at various stages of product lifecycle; the Personalised PageRank algorithm is used to perform knowledge navigation, which finds the most relevant knowledge in knowledge maps for a given problem in new product development. Finally, the feasibility and effectiveness of the proposed approach are demonstrated through a case study and two performance evaluation experiments.","Title: IRelics: Designing a Tangible Interaction Platform for the Popularization of Field Archaeology\nYear: 2019\n\nAbstract: We present IRelics, a tangible interaction platform for the popularization of field archeology. IRelics allows users to experience archaeological field work activities as a serious game by using a set of tangible tools. We developed an innovative LWIR (Long Wavelength Infrared Rays) sensing system, which implements the design of tangible tools that provide real manipulation experiences. By interacting with IRelics, a player may experience different archaeological activities such as excavation and cleaning. We conducted two observations to evaluate the usability and effectiveness at archeology popularizing. Findings suggest that the IRelics platform can enhance the engagement of the participants by providing a positive and interactive environment while teaching them unfamiliar knowledge.","Title: Multiple-place swarm foraging with dynamic depots.\nYear: 2018\n\nAbstract: Teams of robots can be organized to collectively complete complex real-world tasks, for example collective foraging in which robots search for, pick up, and drop off targets in a collection zone. In the previously proposed central-place foraging algorithm (CPFA), foraging performance decreases as swarm size and search areas scale up: more robots produce more inter-robot collisions and larger search areas produce longer travel distances. We propose the multiple-place foraging algorithm with dynamic depots () to address these problems. Depots are special robots which are initially distributed in the search area and can carry multiple targets. Depots move to the centroids of the positions of local targets recently detected by robots. The spatially distributed design reduces robot transport time and reduces collisions among robots. We simulate robot swarms that mimic foraging ants using the strategy, employing a genetic algorithm to optimize their behavior in the robot simulator ARGoS. Robots using the find and collect targets faster than both the CPFA and the static MPFA. outperforms the static MPFA even when the static depots are optimally placed using global information, and it outperforms the CPFA even when the dynamic depots deliver targets to a central location. Further, the scales up more efficiently, so that the improvement over the CPFA and the static MPFA is even greater in large (50 50 m) areas. Including simulated error reduces foraging performance across all algorithms, but the MPFA still outperforms the other approaches. Our work demonstrates that dispersed agents that dynamically adapt to local information in their environment provide more flexible and scalable swarms. In addition, we illustrate a path to implement the in the physical robot swarm of the NASA Swarmathon competition.","Title: Generating Significant Subassemblies From 3d Assembly Models For Design Reuse\nYear: 2018\n\nAbstract: Significant subassemblies are defined as the reusable regions of pre-existing 3D assembly models. A significant subassembly has great significances for design reuse as it aggregates abundant knowledge in a vivid 3D CAD model and enables designers to reuse existing mature designs from a high-level perspective. Consequently, this paper contributes to significant subassembly generation from pre-existing 3D assembly models for design reuse. The paper first gives an explicit definition of significant subassemblies and further explores the multilevel knowledge embedded in these significant subassemblies. Based on the above definition and multilevel knowledge, a knowledge-based approach is then proposed for significant subassembly generation, which includes three phases: (1) identifying candidate subassemblies with high cohesion inside and low coupling outside using the Markov clustering process; (2) removing normal candidate subassemblies with low reusability and less information, and generating filtered subassemblies using the proposed assembly frequency - inverse mean subassembly frequency based scheme; and (3) determining significant subassemblies by measuring the complexity of the filtered subassemblies. Finally, a computer numerical control honing machine model is taken as an application example to demonstrate the effectiveness of the proposed approach.","Title: Application of Mathematical Morphological Filtering to Improve the Resolution of Chang'E-3 Lunar Penetrating Radar Data.\nYear: 2019\n\nAbstract: As one of the important scientific instruments of lunar exploration, the Lunar Penetrating Radar (LPR) onboard China's Chang'E-3 (CE-3) provides a unique opportunity to image the lunar subsurface structure. Due to the low-frequency and high-frequency noises of the data, only a few geological structures are visible. In order to better improve the resolution of the data, band-pass filtering and empirical mode decomposition filtering (EMD) methods are usually used, but in this paper, we present a mathematical morphological filtering (MMF) method to reduce the noise. The MMF method uses two structural elements with different scales to extract certain scale-range information from the original signal, at the same time, the noise beyond the scale range of the two different structural elements is suppressed. The application on synthetic signals demonstrates that the morphological filtering method has a better performance in noise suppression compared with band-pass filtering and EMD methods. Then, we apply band-pass filtering, EMD, and MMF methods to the LPR data, and the MMF method also achieves a better result. Furthermore, according to the result by MMF method, three stratigraphic zones are revealed along the rover's route.","Title: Dam Leakage Detection by Borehole Radar: A Case-History Study.\nYear: 2019\n\nAbstract: A borehole radar investigation was performed at the Sanzuodian reservoir, Chifeng, China to assess possible leakage paths located in the deep dam foundation. The key methodologies used include both single-hole reflection and cross-hole radar tomography, which make a high-resolution identification of the hydraulic connection paths between upstream and downstream sides possible. The leakage paths are characterized by direct wave loss due to high electromagnetic attenuation in the single-hole reflection profile and the nearly horizontal-banded low-velocity zone in the cross-hole velocity tomography due to possible large internal erosion. Meanwhile, some small structures inside the dam, including the core wall thickness changing point, the connecting point between asphalt and concrete walls, and the contacting interface between the dry and the water-saturated formations can be identified from the single-hole reflection profile clearly. Interpreted leakage paths are proven by the water flow measurement. Borehole radar is a useful high-resolution tool, suitable for deep leakage detection and evaluation.","Title: A Novel Graphene Double-Balanced Passive Mixer\nYear: 2018\n\nAbstract: A four-graphene-field-effect-transistor integrated double-balanced mixer is presented in this paper. With 1.59 GHz and 1.61 GHz frequency input, the mixed signals feature an IIP3 of 12.7 dBm, which benefited from the linearity of graphene field effect transistors (GFETs). Due the passive nature of the proposed resistive mixer topology, it has zero power consumption. Size of the chip is smaller than 200 mu m x 200 mu m, integrated by two-metal-layer CMOS back-end-of-line technology. The mixer operates in gigahertz frequency range, consistent with large-signal compact model based simulations.","Title: Linear Prediction-Based DOA Estimation for Directional Borehole Radar 3-D Imaging\nYear: 2019\n\nAbstract: Directional borehole radar (BR) 3-D imaging is a challenging problem due to its limited observation space within a borehole. We present a linear prediction (LP)-based direction-of-arrival (DOA) estimation and a migration-based 3-D imaging algorithm for the directional BR, which is composed of a transmitting antenna and a uniform circular array including four small receiving antennas. Only the azimuth is estimated, while the elevation and the distance are included in the imaging process. LP is a useful tool for DOA estimation in the radar domain, but a single linear array (LA) has azimuth ambiguity in DOA estimation. The four receiving antennas are treated as two orthogonal uniform LAs. The combination of two arrays removes the ambiguity in DOA estimation. In addition, the moving window and the threshold-based estimation increase the calculation efficiency. According to the estimated azimuth angles, the measured signal at each depth is decomposed to the corresponding directions. Therefore, there is a time-series signal in each direction at each depth. After processing the measured signals at all depths, we obtain a 3-D data set that can be used for horizontal- and radial vertical-section displays. Then, the radial vertical-section data are processed by migration which transforms the time domain signal into a wavefield-based 3-D image. Simulated data from a fracture model are used to validate the algorithm, and the reconstructed image can reveal the real model well. It is concluded that the novel method we propose is an effective one with real-time processing capability.","Title: Partial Approximate Controllability for Linear Stochastic Control Systems\nYear: 2019\n\nAbstract: This paper is devoted to studying controllability problems of linear stochastic control systems with controls only in the drift terms. It is well known that such a system is not exactly controllable. We first construct an example to show that it is also not approximately controllable under some natural condition. Next we introduce the notion of partial approximate controllability and reveal that it is equivalent to some weak unique continuation property of backward stochastic evolution equations. Then we prove that this kind of unique continuation property holds. Finally, two examples concerning controlled stochastic parabolic and stochastic Schrodinger equations are presented.","Title: An Integrated Decision-Making Approach On Cutting Tools And Cutting Parameters For Machining Features Considering Carbon Emissions\nYear: 2019\n\nAbstract: Cutting parameters and cutting tools are vital in process planning. Reasonable decision-making of cutting parameters and cutting tools could reduce the processing carbon emissions, time, and cost in machining process. Traditionally, cutting parameter optimization is performed with a preset cutting tool, which limits the potential for carbon emissions savings. In order to globally reduce carbon emissions of machining featuresof parts, this paper provides a new methodology for the integrated optimisation of cutting parameters and cutting tools, where the optimal cutting parameters and cutting tools are identified simultaneously to balance the minimum processing carbon emissions, cost and time for a machining feature of parts. Firstly, a carbon emissions model considering multiple cutting tool flexibilities and corresponding cutting parameters is analyzed and established for a machining feature of parts. Then a multi-objective integration optimisation model of cutting tools and cutting parameters is presented. Thirdly, a NSGA-II algorithm is correspondingly designed to solve the proposed integrated model. Finally, case studies are used to verify the proposed approach. The comparative results show that: i) The integration approach can save more carbon emissions compared with traditional methods; ii) The integrated optimisation methodology can strike a balance among minimum processing carbon emissions, time and cost.","Title: Cognition differences and improvement countermeasures of non-technical medical services based on grey correlation analysis.\nYear: 2019\n\nAbstract: Purpose The purpose of this paper is to explore the rationality differences of cognition of non-technical medical services in different groups, and to provide countermeasures for improving non-technical medical services. Design/methodology/approach Literature analysis, expert interviews, questionnaire survey and frequency analysis were taken to reveal the influencing factors of non-technical medical services. Grey correlation methods were taken to compare the rationality differences of cognition of non-technical medical services by analysis influencing factors' scores marked by different groups. Findings A total of 12 influencing factors of non-technical medical services were obtained, including doctor's working career, doctor's strict implementation of medical treatment norms and medication guidelines, doctor's service awareness, etc. And rationality differences of cognition of non-technical medical services were confirmed as follows: the doctors' cognition was more reasonable compared with patients; the women's cognition was more reasonable compared with men; the lower aged groups' cognition was more reasonable compared with higher aged groups; and people with doctoral degree had a less reasonable cognition compared with others. Originality/value The authors systematically discussed the cognition differences of non-technical medical services among different people, and provided some countermeasures reasonably.","Title: Analysis of patients' attitudes towards medical service prices in different regions based on grey relational theory.\nYear: 2019\n\nAbstract: Purpose The purpose of this paper is to understand the attitude of patients towards the current medical service price and the effect of policy implementation, and explore the existing problems of the current medical service price policy in the region in order to provide a research basis for the dynamic adjustment mechanism of the medical service price. Design/methodology/approach Literature analysis and expert interviews are used to design the questionnaire of the dynamic adjustment of medical service price formation mechanism. A convenient sampling method is used to extract data of 600 patients from the five areas, namely Beijing, Tianjin, Hebei, Shandong and Liaoning, on-site to fill out the paper-based questionnaire and electronic questionnaire. The grey relational analysis is used to explore the difference in the attitudes of patients towards the price of the medical service. Combined with the research results and expert interview results, some improvement suggestions related to the current price policy of medical service in five areas are put forward. Findings The overall average score of respondents in the five areas, namely Beijing, Tianjin, Hebei, Shandong and Liaoning, is found to be 3.861. In terms of surgical operation fee and examination fee, the average score is higher than 4, i.e. 4.097 and 4.011, respectively, indicating relatively high nodes. According to grey relevancy sorting, the correlation between the health service price attitude and the overall score in the five regions is in the following order: Shandong > Tianjin > Beijing > Liaoning > Hebei. Originality/value In this study, patients' attitude towards the current price of medical services in their local areas, Beijing, Tianjin, Hebei, Shandong and Liaoning, is investigated in order to explore the existing problems of medical service price reform and thus provide the basis for further improvement in the medical service price policy.","Title: The investigation and analysis of the current situation of medical service price cognition of China with grey relational analysis theory.\nYear: 2019\n\nAbstract: Purpose Through a questionnaire survey, the purpose of this paper is to understand and analyse the cognitions of medical service price of medical workers in various regions of China, and discuss the policy suggestions on the price dynamic adjustment of medical service. Design/methodology/approach The authors conducted a questionnaire survey on the cognition of medical service price medical workers in various regions of China, and then the grey relational analysis theory is used to analyse the data obtained from the questionnaire survey. Findings The investigation and analysis shows some cognitions of hospital workers on the price of medical services in various regions in China, the authors analyse the results of grey relational analysis and come up with suggestions for relevant departments. Research limitations/implications Although a plenty of research on the current situation of medical service price cognition of China is discussed in the paper, it is not complete; thus, a large amount of information needs to be consulted further. The data obtained from the questionnaire are less used and the utilisation rate is lower, which may result in one-sided results and need further investigation. Practical implications Through the investigation and analysis, the authors can determine about the implementation of medical service prices in various parts of China from the perspective of hospital workers to a certain degree, and try to explore the relevant policy recommendations for the dynamic adjustment of medical service prices. Social implications The price of medical services refers to the fees for registration, diagnosis, inspection, surgery, nursing and medicine. In a narrow sense, the price of medical services refers to the standard of charge for medical services except drugs. This paper mainly refers to the narrow sense. As one of the important means and methods for the government to control the medical service market, medical service price is also an important basis for the economic source of medical institutions. The adjustment of medical service price is related to the interests of all aspects of society. Originality/value Medical service price is an important basis for the economic source of medical institutions, the adjustment of medical service price is related to the interests of all aspects of society and it is a hot issue of social concern. Through the investigation and analysis, the authors use grey relational analysis to know about the medical service prices in various parts of China from the perspective of hospital workers to a certain degree, and try to explore the relevant policy recommendations for the dynamic adjustment of medical service prices.","Title: On-Path Caching Based On Content Relevance In Information-Centric Networking\nYear: 2021\n\nAbstract: The Internet of things (IoT) is a new network concept. Based on the Internet, the idea of connecting everything is proposed, which is likely to become the development direction of computer and communication in the future. Meanwhile, as a disruptive new communication network model, Information-Centric Network (ICN) has become a hot spot in the field of future network architecture research in recent years. ICN is informationcentric, and uses the name of the information to implement data identification, retrieval, and routing and forwarding. The information centric network uses the cache as a built-in structure, and nodes store all the data that flows by default, so that subsequent requests can be responded to as soon as possible. In the actual network, the spread and trend of an information constantly change with time, and the popularity of the information is different in different time periods. However, the existing ICN native caching mechanism ignores the correlation between contents, and the existing relevant research makes insufficient use of content relevance. In this paper may exist a certain correlation between nodes have access to the content of the facts, we design a path cache method based on the correlation content, by discovering target content and the correlation between nodes store content, at the same time considering the node position in the path, make caching decisions, make the cache memory more efficient. The feasibility and effectiveness of the proposed method are verified by simulation experiments under different parameters.","Title: The Dynamic Analysis Of A Novel Reconfigurable Cubic Chaotic Map And Its Application In Finite Field\nYear: 2021\n\nAbstract: Dynamic degradation occurs when chaotic systems are implemented on digital devices, which seriously threatens the security of chaos-based pseudorandom sequence generators. The chaotic degradation shows complex periodic behavior, which is often ignored by designers and seldom analyzed in theory. Not knowing the exact period of the output sequence is the key problem that affects the application of chaos-based pseudorandom sequence generators. In this paper, two cubic chaotic maps are combined, which have symmetry and reconfigurable form in the digital circuit. The dynamic behavior of the cubic chaotic map and the corresponding digital cubic chaotic map are analyzed respectively, and the reasons for the complex period and weak randomness of output sequences are studied. On this basis, the digital cubic chaotic map is optimized, and the complex periodic behavior is improved. In addition, a reconfigurable pseudorandom sequence generator based on the digital cubic chaotic map is constructed from the point of saving consumption of logical resources. Through theoretical and numerical analysis, the pseudorandom sequence generator solves the complex period and weak randomness of the cubic chaotic map after digitization and makes the output sequence have better performance and less resource consumption, which lays the foundation for applying it to the field of secure communication.","Title: Multi-Actor-Attention-Critic Reinforcement Learning for Central Place Foraging Swarms\nYear: 2021\n\nAbstract: Multiple agents with relatively low cost, decentralized control, and robustness have the advantages of completing a foraging task more efficiently than a single advanced robot. Despite many foraging algorithms are efficient in multiple robot systems, most are pre-designed or not very adaptive to different environments since they have to evolve the parameters of the foraging algorithm in each different environment. Besides, designing an efficient collision avoidance strategy for multiple agents is a challenge. Addressing these issues, we introduce the multi-actor-attention-critic(MAAC) reinforcement learning method into the multiple foraging agents. We train the foraging strategy for multiple simulated agents. We compare our approach with existing foraging algorithms for multiple robots, the Central Place Foraging Algorithm (CPFA) and the Distributed Deterministic Spiral Algorithm (DDSA). Experimental results demonstrate that our approach outperforms the two algorithms. Also, we illustrate that our approach has a better performance in avoiding obstacles and adapting to different environments.","Title: Multiple-Place Swarm Foraging with Dynamic Robot Chains\nYear: 2021\n\nAbstract: The goal of foraging robot swarms is to search and deliver resources to a specific central collection zone quickly. In the previously proposed multiple-place foraging algorithm with dynamic depots, foraging performance decreases as search areas and swarm sizes increase: depots need to travel long distances to deliver resources to the center, and more robots produce more congestion on their journeys. We propose a novel extension to the multiple-place foraging in which multiple robot chains are deployed dynamically. Each robot chain connects a foraging location to the central collection zone. Instead of delivering resources by a single robot, resources are passed on robot chains from foraging locations to the center directly such that congestion near the central collection zone can be avoided. Dynamic robot chains can also relocate themselves to get closer to the resources while avoiding obstacles. We simulate our robot swarms in the robot simulator ARGoS. Our experiments show that robots using the MPFA with dynamic chains outperform the MPFA with dynamic depots and have less congestion.","Title: Volumetric segmentation of white matter tracts with label embedding\nYear: 2022\n\nAbstract: •We propose a network that performs volumetric segmentation of white matter tracts.•The tract correlation is exploited with label embedding in the network design.•Our method was validated on public and private datasets under various settings.•The segmentation quality is improved compared with competing methods.•The improvement is more prominent for challenging tracts in challenging scenarios.","Title: CADRE: A Cascade Deep Reinforcement Learning Framework for Vision-Based Autonomous Urban Driving.\nYear: 2022\n\nAbstract: Vision-based autonomous urban driving in dense traffic is quite challenging due to the complicated urban environment and the dynamics of the driving behaviors. Widely-applied methods either heavily rely on hand-crafted rules or learn from limited human experience, which makes them hard to generalize to rare but critical scenarios. In this paper, we present a novel CAscade Deep REinforcement learning framework, CADRE, to achieve model-free vision-based autonomous urban driving. In CADRE, to derive representative latent features from raw observations, we first offline train a Co-attention Perception Module (CoPM) that leverages the co-attention mechanism to learn the inter-relationships between the visual and control information from a pre-collected driving dataset. Cascaded by the frozen CoPM, we then present an efficient distributed proximal policy optimization framework to online learn the driving policy under the guidance of particularly designed reward functions. We perform a comprehensive empirical study with the CARLA NoCrash benchmark as well as specific obstacle avoidance scenarios in autonomous urban driving tasks. The experimental results well justify the effectiveness of CADRE and its superiority over the state-of-the-art by a wide margin.","Title: A transfer learning approach to few-shot segmentation of novel white matter tracts\nYear: 2022\n\nAbstract: •We explore knowledge transfer for few-shot segmentation of novel WM tracts.•A model pretrained for segmenting existing WM tracts is given.•We derive a better network initialization for segmenting novel WM tracts.•Data augmentation is further applied with tract-aware image mixing.•Our method was validated on public and private datasets under various settings.","Title: Assessing the Effects of Induced Field Rotation on Water Ice Detection of Tianwen-1 Full-Polarimetric Mars Rover Penetrating Radar\nYear: 2022\n\nAbstract: China's first Mars probe Tianwen-1 has successfully landed on the southern Utopia Planitia of Mars on May 15, 2021. The Zhurong rover is first equipped with a full-polarimetric Mars Rover Penetrating Radar (FP-RoPeR) system, aiming to map the subsurface fine structure and to find the potential underground water ice. However, different from the previous water ice detection of orbital radar, the FP-RoPeR signals will be affected by the induced field rotation (IFR) if electromagnetic (EM) waves propagate through rough interfaces. Therefore, in this article, we assess the IFR effects from rough interfaces on the circular polarization ratio (CPR) response of FP-RoPeR data, which is a significant parameter for water ice detection. The theoretical computation and numerical validation indicate that the depth, the number of rough interfaces, and relative permittivity are three vital parameters that affect the IFR effects; depth plays a more important role than the other two for FP-RoPeR system. The CPR estimation result will be with greater error in the shallow region (0-1 m). The relative error in the region of depth greater than 1 m can be guaranteed to be under 10%.","Title: O&O: A DIY toolkit for designing and rapid prototyping olfactory interfaces\nYear: 2022\n\nAbstract: ABSTRACTConstructing olfactory interfaces on demand requires significant design proficiency and engineering effort. The absence of powerful and convenient tools that reduced innovation complexity posed obstacles for future research in the area. To address this problem, we proposed O&O, a modular olfactory interface DIY toolkit. The toolkit consists of: (1) a scent generation kit, a set of electronics and accessories that supported three common scent vaporization techniques; (2) a module construction kit, a set of primitive cardboard modules for assembling permutable functional structures; (3) a design manual, a step-by-step design thinking framework that directs the decision-making and prototyping process. We organized a formal workshop with 19 participants and four solo DIY trials to evaluate the capability of the toolkit, the overall user engagement, the creations in both sessions, and the iterative suggestions. Finally, design implications and future opportunities were discussed for further research.","Title: Shape-driven lightweight CNN for finger-vein biometrics\nYear: 2022\n\nAbstract: Finger-vein recognition has been widely explored for biometrics security over the past two or three decade. Its size and characteristics against presentation attacks make it suitable for various commercial, governmental and forensics applications. As with other biometric traits, finger-vein recognition approaches mainly depend on well-engineering feature descriptors and recently, more deep learning (DL) models have been designed to achieve high-performance biometrics. However, the existing DL approaches usually employ the neural networks with increasing layers and parameters, which inevitably leads to an increase in memory consumption and algorithm complexity. Besides, all the vein recognition networks use square filters, which are influenced by network designed for object detection and classification. In this paper, two network design issues for finger-vein recognition are explored: shallow network using rectangular filters and lightweight semi-pretrained network. The exhaustive experiments on three benchmark databases HKPU, FV-USM and SDUMLA demonstrate that rectangular filters outperform square filters for DL-based finger-vein recognition, and the lightweight semi-pretrained network also outperforms non-pretrained network.","Title: Simulation of Borehole Radar Responses to Rough Fractures Based on 3-D Conformal FDTD\nYear: 2022\n\nAbstract: Borehole radar is a powerful tool for detecting subsurface fractures. Fracture modeling and numerical simulation are essential means to study fracture detectability. In this article, we first propose a method to construct a single fracture model, which combines the Baecher disk model and random rough surface and includes features, such as roughness, pinch-out, and irregularity. As the precise description of the fracture raises the requirement for accuracy of the simulation algorithm, the 3-D conformal finite-difference time-domain (CFDTD) method is used in this work. Numerical simulations of a sphere and rough fractures show that the CFDTD has higher calculation accuracy than conventional FDTD. Then, we analyzed how the fractures with different roughness affect the electromagnetic wave response. It is found that as the fracture surface becomes rougher, the wave scattered by it becomes stronger, more fracture contour-related information is obtained, and the fracture morphology is recovered better. Combined with accurate fracture modeling and high-precision numerical simulation, the electromagnetic response characteristics of different forms of fractures are obtained, which provides a basis for the accurate detection and interpretation of fractures in the future.","Title: Environmental assisted cracking and strength attenuation effect computing on the mechanical properties of casing steel P110 for industrial revolution 5.0 applications in sour well environments\nYear: 2022\n\nAbstract: Casing steel is prone to reduced mechanical properties and occurred environmentally assisted cracking finally in sour well environment containing H2S and CO2. The paper mainly researched on the relationship between mechanical properties and hydrogen permeation, exposed casing steel P110 to air, NACE A solution, and simulated formation water containing H2S and CO2 with a stress of 80% yield strength at 60 °C for 168 h, testing its mechanical properties shown strain-aging phenomenon and ductile–brittle transition. The lowest mechanical properties are occurred in the sour well environment, its yield strength, and tensile strength, respectively, reduction 5.0% and 4.7%, while a loss of 41.4% in fracture toughness. With temperature increased from 25 to 60 °C, the hydrogen diffusion coefficient increases by 1.59 times, and there is a mutation in mechanical properties of P110, when the hydrogen diffusion coefficient is 1.64 × 10–4 cm2/s and the subsurface hydrogen concentration is.1.653 × 10–5%. The steel P110 has shown a ductile fracture with toughnest exposed in the air and shown cleavage fracture characteristics exposed to sour environments, indicating that hydrogen permeation has changed the fracture mode from ductile to brittle. This method can be used to test and compute the strength attenuation effect of casing P110 serviced in sour well environments.","Title: Particle Swarm Optimization-Based Variational Mode Decomposition for Ground Penetrating Radar Data Denoising\nYear: 2022\n\nAbstract: Ground Penetrating Radar (GPR) has become a widely used technology in geophysical prospecting. The Variational Mode Decomposition (VMD) method is a fully non-recursive signal decomposition method with noise robustness for GPR data processing. The VMD algorithm determines the central frequency and bandwidth of each Intrinsic Mode Function (IMF) by iteratively searching for the optimal solution of the variational mode and is capable of adaptively and effectively dividing the signal in the frequency domain into the many IMFs. However, the penalty parameter alpha and the number of IMFs K in VMD processing are determined depending on manual experience, which are important parameters affecting the decomposition results. In this paper, we propose a method to automatically search the parameters alpha and K optimally by Particle Swarm Optimization (PSO) algorithm. Then the signal-to-noise ratio (SNR) and root-mean-square error (RMSE) are used to judge the best superposition of the IMFs for data reconstruction, and the process is data-driven without human subjective intervention. The proposed method is used to process the field data, and the reconstruction data show that this innovative VMD processing can effectively improve the SNR and highlight the target reflections, even some targets not found in pre-processing are also revealed.","Title: Channel Condition and Outage Performance of Mode-Division-Multiplexing Enabled MIMO System With Zero-Forcing Receiver\nYear: 2022\n\nAbstract: Reusing the widely deployed multimode fibers (MMFs) in buildings to transmit multiple-input multiple-output (MIMO) signals via mode-division multiplexing (MDM) is an attractive solution to provide low-cost indoor wireless coverage. However, due to the random mode coupling, MMF channel varies over time. In this letter, the MDM-based MMF MIMO channel condition for different fiber lengths is studied. Next, the influence of the fluctuation of channel condition on the outage performance of the MIMO system with zero-forcing receiver is analyzed, in terms of information-theoretic capacity and practical error probability. Finally, by using adaptive coded modulation (according to channel condition), the MDM-based \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$3 \\times 3$ </tex-math></inline-formula>\n MIMO channel achieves up to 8.62 bit/s/Hz spectral efficiency with 10% outage probability.","Title: One-Shot Segmentation of Novel White Matter Tracts via Extensive Data Augmentation\nYear: 2022\n\nAbstract: Deep learning based methods have achieved state-of-the-art performance for automated white matter (WM) tract segmentation. In these methods, the segmentation model needs to be trained with a large number of manually annotated scans, which can be accumulated through- out time. When novel WM tracts i.e., tracts not included in the existing annotated WM tracts are to be segmented, additional annotations of these novel WM tracts need to be collected. Since tract annotation is time-consuming and costly, it is desirable to make only a few annotations of novel WM tracts for training the segmentation model, and previous work has addressed this problem by transferring the knowledge learned for segmenting existing WM tracts to the segmentation of novel WM tracts. However, accurate segmentation of novel WM tracts can still be challenging in the one-shot setting, where only one scan is annotated for the novel WM tracts. In this work, we explore the problem of one-shot segmentation of novel WM tracts. Since in the one-shot setting the annotated training data is extremely scarce, based on the existing knowledge transfer framework, we propose to further perform extensive data augmentation for the single annotated scan, where synthetic annotated training data is produced. We have designed several different strategies that mask out regions in the single annotated scan for data augmentation. To avoid learning from potentially conflicting information in the synthetic training data produced by different data augmentation strategies, we choose to perform each strategy separately for network training and obtain multiple segmentation models. Then, the segmentation results given by these models are ensembled for the final segmentation of novel WM tracts. Our method was evaluated on public and in-house datasets. The experimental results show that our method improves the accuracy of one-shot segmentation of novel WM tracts.","Title: Backstepping Fuzzy Adaptive Control Based on RBFNN for a Redundant Manipulator\nYear: 2022\n\nAbstract: Redundant manipulator is a highly nonlinear and strongly coupled system. In practical application, dynamic parameters are difficult to determine due to uncertain loads and external disturbances. These factors will adversely affect the control performance of manipulator. In view of the above problems, this paper proposes a backstepping fuzzy adaptive control algorithm based on the Radial Basis Function Neural Network (RBFNN), which effectively eliminates the influence of the internal uncertainty and external interference on the control of the manipulator. Firstly, the algorithm adopts the backstepping method to design the controller framework. Then, the fuzzy system is used to fit the unknown system dynamics represented by nonlinear function to realize model-free control of the manipulator. The fuzzy constants are optimized by RBFNN to effectively eliminate the control errors caused by unknown parameters and disturbance. Finally, in order to realize RBFNN approximating the optimal fuzzy constant, an adaptive law is designed to obtain the weight value of RBFNN. The stability of the closed-loop system is proved by using Lyapunov stability theorem. Through simulation experiments, the algorithm proposed in this paper can effectively track the target joint angle when the dynamic parameters of the 7-DOF redundant manipulator are uncertain and subject to external torque interference. Compared with fuzzy adaptive control, the tracking error of the algorithm in this paper is smaller, and the performance is better.","Title: Spatiotemporal Variation in Vegetation Growth Status and Its Response to Climate in the Three-River Headwaters Region, China\nYear: 2022\n\nAbstract: The Three-River Headwaters Region (TRHR), located in the hinterland of the Qinghai-Tibet Plateau (QTP), is an important water-conservation and ecological-function reserve in China. Studies of the growth of vegetation in the TRHR and its response to climate under the background of global warming are of great relevance for ecological protection of the QTP. In this study, based on MOD13Q1 Enhanced Vegetation Index (EVI) data and ERA5-Land climate data, the ensemble empirical mode decomposition method, random forest algorithm, and Hurst exponent were used to detect the spatiotemporal dynamics and response to climate change in TRHR vegetation during 2000-2021. The results indicated the following. (1) Comparatively, the condition of vegetation growth was better in 2021, 2010, and 2018 and poorer in 2015, 2003, and 2008. The EVI gradually decreased from the southeast to the northwest, and the area of improved vegetation growth was larger than the area of degraded vegetation growth. (2) The area of zones with either monotonous greening or monotonous browning of vegetation was 30.30% and 6.30%, respectively, and the trend of reversed vegetation change occurred in 63.40% of the areas. The area of future degradation of vegetation in the TRHR was larger than the area of future improvement, and the risk of vegetation degradation was higher. (3) Precipitation and soil temperature are the main and secondary driving factors of vegetation change in the TRHR, respectively. Warming and humidification of the QTP climate play major roles in the improvement of vegetation growth in the TRHR."],"string":"[\n \"Title: Efficient Large-Scale Access Control for Internet/Intranet Information Systems\\nYear: 1999\\n\\nAbstract: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099. Access control is a key problem for information processing, especially in a distributed environment such as the Internet and Intranet, where diverse information resources will be made available for \\\"diverse\\\" users to query. We present an efficient method for large scale access control problem. It main ingredient is a representation of hierarchical access group structures as intervals over integers and a decomposition scheme that reduces any group structure to ones that have interval representations. This representation allows the problem for checking access rights to be reduced to an interval containment problem.\",\n \"Title: Performance analysis for optical wireless communication systems using subcarrier PSK intensity modulation through turbulent atmospheric channel.\\nYear: 2004\\n\\nAbstract: This paper compares the performance of on-off keying (OOK) modulation and subcarrier phase shift keying (PSK) modulation through optical wireless channel. The bit error rate (BER) for turbulence channel is derived for optical wireless communication systems employing OOK or subcarrier BPSK. A lower bound is derived for BER performance when fixed-threshold OOK is used. It is also shown that the BER performance of the optical wireless communication system employing subcarrier PSK modulation is more than 3 dB better than that of a compatible system employing fixed-threshold OOK modulation at BER = 10(-6) and with turbulence parameter sigma = 0.1. When sigma is 0.2 and fixed-threshold OOK is: employed, the BER performance never falls down to 10(-4). The BER performance degradation of optical wireless communication systems employing subcarrier BPSK between sigma = 0.1 and sigma = 0.2 is only 2.5 dB at BER = 10(-6).\",\n \"Title: Developing a novel full-polarimetric GPR technology\\nYear: 2011\\n\\nAbstract: Generally GPR transmits and receives radio waves with a single polarization using two parallel antennas. But it is possible to improve the GPR ability of discrimination and imaging of subsurface targets by analyzing the backscattered wave with a variety of polarizations. So we are developing a full-polarimetric GPR system, including PC, network analyzer, rectangular coordinates robot, switch driver, and polarimetric antenna array. Polarimetric antenna array is used to transmit and receive both co-polarimetric and cross-polarimetric signals. Currently polarimetric GPR do not execute precise calibration. But good calibration can improve the classification ability of subsurface targets. So we introduced the calibration technique into the polarimetric GPR, and derived a calibration formula.\",\n \"Title: Developing calibration technology for full-polarimetric GPR\\nYear: 2012\\n\\nAbstract: Polarimetric GPR requires accurate calibration of channel imbalance and crosstalk not only in the amplitude term but also in the phase term. Currently, there have some calibration techniques. Though these techniques are very easy to perform, they provide less accurate calibration results for the crosstalk. To improve on the accuracy of calibration, we have developed a mathematical formulation to calibrate polarimetric GPR data. We measured several scattering matrices to obtain the necessary calibration parameters. The calibration technique was tested from measurements conducted on dihedral corner reflector.\",\n \"Title: 3D velocity model and ray tracing of antenna array GPR\\nYear: 2010\\n\\nAbstract: Migration is an important signal processing method that can improve signal-clutter ratio and reconstruct subsurface image. Diffraction stacking migration and Kirchhoff migration sum amplitudes along the migration trajectory, which generally is hyperbolic. But when the ground surface varies acutely, the migration trajectory is not hyperbolic. To computer the migration trajectory need the technique of ray tracing. We introduce a method of ray tracing based on 3D velocity model. Firstly, we build the 3D velocity model depending on the estimation of both ground surface topography and velocities. Then we compute the travel time between transmitter, receiver and each subsurface scattering point, and search the propagation ray depending on the Fermat's principle. The method is tested by an experiment data acquired by the stepped-frequency (SF) CMP antenna GPR system. The target is a metal ball that is buried under a sand mound. A nice result of ray tracing is shown in the case.\",\n \"Title: Organizing the digital world to empower people to do more, know more, and be more\\nYear: 2014\\n\\nAbstract: The web is rapidly evolving into the web of the world where people, places, things and their relationships are all digitally represented. This evolution opens up unparalleled opportunities to organize this vast digital universe for even greater human purpose. In this talk, Dr. Lu will share an outline of Microsoft's quest and aspiration to organize the digital universe with a pervasive computational fabric of digital information, digital services, and digital experiences that empower every human being on the planet to accomplish more and enrich their life. Dr. Lu will discuss high level computational structures and present specific examples across Bing, Windows and other products and services to illustrate Microsoft's approach to delivering end user value and accelerating the pace of innovation for the industry as a whole.\",\n \"Title: Carleman Estimate For Stochastic Parabolic Equations And Inverse Stochastic Parabolic Problems\\nYear: 2011\\n\\nAbstract: In this paper, we establish a global Carleman estimate for stochastic parabolic equations. Based on this estimate, we study two inverse problems for stochastic parabolic equations. One is concerned with a determination problem of the history of a stochastic heat process through the observation at the final time T for which we obtain a conditional stability estimate. The other is an inverse source problem with observation on the lateral boundary. We derive the uniqueness of the source.\",\n \"Title: Subsurface imaging by modified migration for irregular GPR data\\nYear: 2012\\n\\nAbstract: Handheld ground-penetrating radar (GPR) system is one of a number of technologies that has been researched as a means of improving landmine detection efficiency. However, as the measurement points are random and data are irregular for the human operator, it is difficult to display subsurface visualization imaging. Also detection of buried landmines by GPR normally suffers from very strong clutter that will decrease the image quality. To solve the problem, a modified migration algorithm was proposed to process irregular GPR data, which has both the advantage of migration that can improve signal-clutter ratio and the advantage of interpolation that produces the grid data set for visualization. An application to field data acquired in Afghanistan shows clear landmine image in both vertical profile and horizontal slice.\",\n \"Title: Parallel Profile Matching for Large Scale Webcasting\\nYear: 1998\\n\\nAbstract: Profile matching is a key problem for webcasting systems. In such a system, each user has a personal profile. Each information document is matched with profiles in a profile-database, and pushed only to those users whose profiles match the content of the document. We present an efficient and scalable parallel profile matching algorithm which can handle a large subscription volume and diversity of information content. Our algorithm automatically partitions the profile database for load balancing and minimizes the interaction among processors in parallel profile matching. It has a dynamic load balancing mechanism for handling profile updates. We describe the implementation of our algorithm in the context of the Grand Central Station (GCS) project at the IBM Almaden Research Center. The initial performance evaluation indicates that parallel profile matching can be scaled up gracefully via dynamic adaptation.\",\n \"Title: Fractal Curve and Attribute Grammar\\nYear: 1988\\n\\nAbstract: Without Abstract\",\n \"Title: Group mobility support in mobile WiMAX networks\\nYear: 2011\\n\\nAbstract: Group mobility refers to the scenarios that multiple mobile stations (MSs) move in a group at the same time, generally in the same direction with a short distance of separation. In the normal operation, when the group of MSs moves out of the coverage of the current serving BS and into that of another BS, multiple handovers processes should be performed at almost the same time. Large latency will be incurred due to the collisions of the ranging requests from the MSs in the group and the extra time for the corresponding backoff. Especially, when the number of MSs in the group is larger, the handover latency becomes much more significant and it would affect transmissions seriously. In this paper, we propose a group handover scheme to design an efficient and effective handover process with low latency for the group mobility scenarios in the mobile WiMAX networks. The Bridge MS is introduced to integrate several handover processes for the group of MSs into only one, which could eliminate the collision of the ranging requests and shorten the latency incurred. The results of the evaluation show that much lower handover latency for the group of MSs during the handover could be obtained by the proposed scheme and the improvement becomes significant as the number of MSs is increased in the group.\",\n \"Title: Achieving Faster Handovers in Mobile WiMAX Networks\\nYear: 2012\\n\\nAbstract: WiMAX is a wireless metropolitan area network (WMAN) specified by IEEE 802.16. It provides the broadband wireless access for mobile devices. In such a system, to enable the mobility, the handover is supported to maintain the connectivity of the mobile station (MS) when it moves from the coverage of the serving base station (BS) to the coverage of a neighbor BS. In the handover process, scanning is required to find a suitable target BS, and network re-entry is needed to establish the new connection. However, in the standard handover process, a long latency to data transmissions is caused resulting in the serious interruption to ongoing services. In this paper, an improved handover scheme is proposed to reduce the latency introduced in the handover process by shortening the scanning and enhancing the network re-entry. The proposed scanning strategy reduces the latency by reducing the number of neighbor BSs to be scanned through estimating the rough location of the MS. The enhanced network re-entry reduces the delay by updating transport connection identifiers (CIDs) early to allow the fast resumption of active applications. Simulations were conducted to evaluate the performance of the proposed handover scheme. The results show that the proposed handover scheme reduces the data transmission latency during handover significantly.\",\n \"Title: Collaborative Web Crawling: Information Gathering/Processing over Internet\\nYear: 1999\\n\\nAbstract: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099. In this paper, we present a scalable method for collaborative web crawling and information processing. The method includes an automatic cyberspace partitioner which is designed to dynamically balance and re-balance the load among processors. It can be can be used when all web crawlers are located on a tightly coupled high-performance system as well as when they are scattered in a distributed environment. We have implemented our algorithms in Java as a part of the IBM Grand Central Station (GCS) system.\",\n \"Title: Improving data consistency in mobile computing using isolation-only transactions\\nYear: 1995\\n\\nAbstract: Disconnected operation is an important technique for providing mobile access to shared data in distributed file systems. However, data inconsistency resulting from partitioned sharing remains a serious concern. This paper presents a new mechanism called isolation-only transaction (IOT) that uses serializability constraints to automatically detect read/write conflicts. The IOT consistency model provides a set of options for automatic and manual conflict resolution. In addition, application-specific knowledge can be incorporated to detect and resolve conflicts. To preserve upward Unix compatibility, the IOT mechanism is provided as an optional file system facility and its flexible interfaces allow any existing Unix application to be executed as an IOT. This paper describes high-level system design and implementation and concludes with related work and current status\",\n \"Title: Performance of Phase Modulated Systems Using Fully Saturated Power Amplifiers\\nYear: 2004\\n\\nAbstract: This paper studies the performances of BPSK and QPSK modulations amplified by fully saturated power amplifiers. To achieve better performance, both convolutional code and Turbo code are used. Viterbi decoding and iterative turbo decoding are employed in the receiver, respectively. Simulation results show that good BER performance can be achieved when signal is amplified by fully saturated power amplifiers and transmitted through AWGN channel. The SNR degradation is 0.7 dB for BPSK and 0.3-0.4 dB for QPSK at BER= 10(-5).\",\n \"Title: Singularity Analysis Of Planar Cable-Driven Parallel Robots\\nYear: 2008\\n\\nAbstract: It is well known that parallel robots may have singular configurations that can result in a loss of full control the mechanisms. This paper analyzes two different categories of singularities of planar cable-driven parallel robots with four or more cables. The unidirectional constraint of cables makes the singularity analysis of cable-driven parallel robots different from that of rigid-link parallel robots even if they have similar kinematical architectures. Based on their natures, singularities of cable-driven parallel robots are classified into two categories: the Jacobian singularity and the force-closure singularity. A Jacobian singularity occurs when the Jacobian matrix of a cable-driven parallel robot loses its full rank. Based on rank analysis of Jacobian matrix, a group of Jacobian singularities is reported with mathematical proof. When the Jacobian matrix of a cable-driven parallel robot has a full rank, the cables' inability to generate tension will lead to force-closure singularities, which can always happen to fully-constrained cable-driven parallel robots. An algorithm of identifying force-closure singularities of planar cable-driven parallel robots is proposed. Understanding of the natures of singularities is important for the design and control of cable-driven parallel robots.\",\n \"Title: Future of the web and search\\nYear: 2011\\n\\nAbstract: No one doubts that we have only scratched the surface of what is possible with the Web. The day is coming fast when the Web will become almost a virtual mind reader. Your intent, interests, and needs will be instantly perceived and the information you want will be promptly delivered -- whether you ask for it directly or not -- based on a deep understanding of the meaning of words in your query, knowledge of your preferences and patterns, what others have done before you, your location, and more. In this talk, I will share some of my thoughts about where the Web is heading and how search will be transformed to align to this new Web, laying out some specifics behind Microsoft's vision to empower people with knowledge.\",\n \"Title: BigDL: A Distributed Deep Learning Framework for Big Data.\\nYear: 2018\\n\\nAbstract: ThispaperpresentsBigDL (adistributeddeeplearning framework for Apache Spark), which has been used by a variety of users in the industry for building deep learning applications on production big data platforms. It allows deep learning applications to run on the Apache Hadoop/Spark cluster so as to directly process the production data, and as a part of the end-to-end data analysis pipeline for deployment and management. Unlike existing deep learning frameworks, BigDL implements distributed, data parallel training directly on top of the functional compute model (with copy-on-write and coarse-grained operations) of Spark. We also share real-world experience and \\\"war stories\\\" of users that havead-optedBigDLtoaddresstheirchallenges(i.e., howtoeasilybuildend-to-enddataanalysisanddeep learning pipelines for their production data).\",\n \"Title: Reachability analysis for timed automata using max-plus algebra.\\nYear: 2012\\n\\nAbstract: We show that max-plus polyhedra are usable as a data structure in reachability analysis of timed automata. Drawing inspiration from the extensive work that has been done on difference bound matrices, as well as previous work on max-plus polyhedra in other areas, we develop the algorithms needed to perform forward and backward reachability analysis using max-plus polyhedra. To show that the approach works in practice and theory alike, we have created a proof-of-concept implementation on top of the model checker opaal.\",\n \"Title: Resource conservation in a mobile transaction system\\nYear: 1997\\n\\nAbstract: This paper addresses the problem of providing transactional support for improved data consistency in mobile file access, while paying careful attention to the resource constraints of mobile clients. We present data on resource consumption from an implementation of the isolation-only transaction (IOT) mechanism of the Coda File System. The data shows that the resource conservation techniques used by the IOT mechanism do indeed result in modest demands on the three critical resources on a mobile client: CPU and I/O usage, disk space, and RVM space. Overall, our measurements confirm that even a severely resource-constrained mobile client can benefit from the improved consistency offered by the IOT mechanism\",\n \"Title: Boosting for Multi-Modal Music Emotion Classification.\\nYear: 2010\\n\\nAbstract: With the explosive growth of music recordings, automatic classification of music emotion becomes one of the hot spots on research and engineering. Typical music emotion classification (MEC) approaches apply machine learning methods to train a classifier based on audio features. In addition to audio features, the MIDI and lyrics features of music also contain useful semantic information for predicting the emotion of music. In this paper we apply AdaBoost algorithm to integrate MIDI, audio and lyrics information and propose a two-layer classifying strategy called Fusion by Subtask Merging for 4-class music emotion classification. We evaluate each modality respectively using SVM, and then combine any two of the three modalities, using AdaBoost algorithm (MIDI+audio, MIDI+lyrics, audio+lyrics). Moreover, integrating this in a multimodal system (MIDI+audio+lyrics) allows an improvement in the overall performance. The experimental results show that MIDI, audio and lyrics information are complementary, and can be combined to improve a classification system. © 2010 International Society for Music Information Retrieval.\",\n \"Title: Experience with Disconnected Operation in a Mobile Computing Environment\\nYear: 1994\\n\\nAbstract: In this paper we present qualitative and quantitative data on file access in a mobile computing environment. This information is based on actual usage experience with the Coda File System over a period of about two years. Our experience confirms the viability and effectiveness of disconnected operation. It also exposes certain deficiencies of the current implementation of Coda, and identifies new functionality that would enhance its usefulness for mobile computing. The paper concludes with a description of what we are doing to address these issues.\",\n \"Title: A New Scheme to Mitigate the OFDM High PAR Problem by Minimizing the Signal's Nonlinear Distortion Caused by HPA\\nYear: 2006\\n\\nAbstract: How to mitigate the negative impact of high PAR in OFDM systems is an important issue. Most of recent works have focused on minimizing the PAR of OFDM signal to enhance performance. However, after relating this issue with the specific characteristics of HPA, we propose a new scheme to mitigate the high PAR problem. Rather than minimizing OFDM signal's PAR, the new scheme uses the amount of OFDM signal's nonlinear distortion to be caused by HPA as a new measure and increases the performance of OFDM system by minimizing this nonlinear distortion. The pre-calculation of the new measure is achieved by employing an adaptive nonlinear system identification process. Meanwhile, because the new scheme only changes the measure of the OFDM signal but not the frameworks of the prior PAR-reduction methods based on minimum PAR criterion, these prior PAR-reduction methods can be easily extended to incorporate the new scheme. A case study of the new scheme by adopting it in the SLM method shows its superiority over the conventional scheme\",\n \"Title: Efficient profile matching for large scale Webcasting\\nYear: 1998\\n\\nAbstract: This paper presents an efficient method of matching diverse data against user profiles in large-scale Webcasting systems. Its design and implementation are described in the context of the Grand Central Station (GCS) project at IBM Almaden Research Center. Initial performance evaluation indicates the ability of GCS profile matching to scale up and achieve strong performance via dynamic adaptation.\",\n \"Title: Geometric quantifier elimination heuristics for automatically generating octagonal and max-plus invariants\\nYear: 2013\\n\\nAbstract: Geometric heuristics for the quantifier elimination approach presented by Kapur (2004) are investigated to automatically derive loop invariants expressing weakly relational numerical properties (such as l≤x≤h or l≤±x ±y≤h) for imperative programs. Such properties have been successfully used to analyze commercial software consisting of hundreds of thousands of lines of code (using for example, the Astrée tool based on abstract interpretation framework proposed by Cousot and his group). The main attraction of the proposed approach is its much lower complexity in contrast to the abstract interpretation approach (O(n2) in contrast to O(n4), where n is the number of variables) with the ability to still generate invariants of comparable strength. This approach has been generalized to consider disjunctive invariants of the similar form, expressed using maximum function (such as max (x+a,y+b,z+c,d)≤max (x+e,y+f,z+g,h)), thus enabling automatic generation of a subclass of disjunctive invariants for imperative programs as well.\",\n \"Title: Isolation-only transactions for mobile computing\\nYear: 1994\\n\\nAbstract: 1. Motivation The Unix File System(UFS) has historically offered a shared-memory consistency model. The lack of concurrency control makes this model susceptible to read/write conflicts, i.e., unexpected read/write sharing between two different processes. For example, the update of a header file by one user while another user is performing a long-runningmake can cause inconsistencies in the compilation results. In practice, read/write conflicts are rare for two reasons. First, the window of vulnerability is relatively small because read/write conflicts only occur when the executions of two processes overlap. Second, they are often prevented via explicit user-level coordination. However, the advent of mobile computing makes read/write conflicts a realistic threat to data integrity. Mobile computing is characterized by periods of disconnection and intermittent connectivity(11). Such communication disturbances greatly widen the window of vulnerability from the life span of a process to the duration of a disconnection. They also significantly reduce the effectiveness of explicit user-level coordination, especially when disconnections are made transparent to users. How can we preserve upward compatibility with the large body of existing Unix software, while offering improved consistency in a mobile computing environment? This position paper puts forth our solution, a new transaction model called isolation only transaction (IOT).\",\n \"Title: Data mining in the online services industry\\nYear: 2010\\n\\nAbstract: The online services industry is a rapidly growing industry with a worldwide online ad market projected to grow from $48 billion in 2011 to $67 billion in 2013, of which 47% will come from display advertising and 53% from search advertising. Online Services Division (OSD) within Microsoft is a leader in the consumer cloud space today with a strong portfolio of a set of 3 mutually reinforcing businesses: Search, Portal, Advertising. They are supported by a shared foundational asset of Intent & Knowledge Stores and a shared technology platform supporting large scale data and high performance systems. MSN (Portal) and Bing (Search) generate the content, traffic and data, that make for an exciting fertile environment for large scale data mining practice and system development. Our advertisers are thus given more valuable targeting opportunities and better ROI, which in turn, provide better economics, usability data, and allows for a higher quality services for our advertisers and experience for our users. The ability to transform data into meaningful, actionable insight is an important source of competitive advantage for OSD. The data mining initiatives within the division continue to strive for excellence around the following goals: actionable insights through deep data analysis, data mining and data modeling at scale and with speed, increased productivity from deployed large scale data systems and tools, improved product and service development and decision making gained from effective measurement and experimentation, and a mature data culture in product teams that made the above possible. With many technical and data challenges ahead of us, we are committed to utilizing our huge data asset well to understand the need, intent, and behavior of our users for the purpose of serving them better.\",\n \"Title: Design, Proof and Analysis of New Efficient Algorithms for Incremental Attribute Evaluation\\nYear: 1988\\n\\nAbstract: Without Abstract\",\n \"Title: Calibration with high-order terms of polarimetric GPR\\nYear: 2012\\n\\nAbstract: To provide meaningful data, polarimetric ground penetrating radar (GPR) requires accurate calibration of channel imbalance and crosstalk not only in the amplitude term but also in the phase term. Currently, calibration techniques usually ignore higher-order terms to simplify equations. These techniques, though very easy to perform, provide less accurate calibration results for the crosstalk. To im...\",\n \"Title: Modeling of forced convection heat transfer from the swing plate on an industrial robot\\nYear: 2014\\n\\nAbstract: The swing plate on an industrial robot is a sort of disk-like component through which an amount of heat generated inside the robot axis 1 drivetrain will transfer to the ambient. This raises a need on modeling and design of the swing plate from a thermal perspective. However, it still remains questionable whether or not the thermal models developed for conventional type of rotating disks are applicable to the swing plate on a robot. This is because, not like the conventional spinning disk which rotates in a single direction continuously, the swing plate is driven back-and-forth in a bi-directional mode, called rotary reciprocation. This paper aims to understand the convection heat transfer properties of such a swing plate by conducting a set of experiments with a plate undergoing rotary reciprocation. A set of empirical models are then assessed by comparing against the experimental results, and eventually, the model that best describes forced convection of the swing plate is obtained.\",\n \"Title: Ground water migration monitoring by GPR\\nYear: 2002\\n\\nAbstract: In order to understand the capability of monitoring ground water movement by ground penetrating radar (GPR), we carried out a field survey in Mongolia. We controlled water production at a ground water source area and the change of ground water level at about 5 m in depth could be detected by GPR. The change of the ground water level was observed more than 15 m in the radial distance from the pumping well. The change of the vertical water content was also evaluated by GPR.\",\n \"Title: Model-Based Temperature Estimation Methods In Design Of Industrial Manipulator And Their Assessment\\nYear: 2015\\n\\nAbstract: Estimation of the steady state temperature rise of an industrial manipulator and its key components is often desired in the design of a manipulator. This paper presents and compares three model-based methods which aim to achieve the temperature estimation in early design phase before prototype test. The basic idea of each method is introduced along with the results of corresponding experimental verifications. The verifications basically demonstrates the feasibility of the methods. The accuracy of the temperature estimation by all three methods is acceptable for use in early design phase. A brief assessment of the methods is also presented which should be helpful for users to select the most suitable method in design practice.\",\n \"Title: Freeway ramp metering based on genetic algorithm optimization\\nYear: 2015\\n\\nAbstract: Contraposing the complexity of a ramp control problem, we propose a method of proportional plus integral (PI) control and genetic algorithm optimization for ramp metering in this paper. Firstly, we build a cell transmission model (CTM) for freeway traffic. After that, we design several ramp controllers based upon CTM and feedback control method, and give the optimization process of a genetic algorithm in detail for optimizing the PI parameters. Finally, we simulate the ramp controllers by computer. Simulation reveals that the ramp metering controllers based on genetic algorithm optimization are of good performance. This control method can stabilize traffic flow as well as improve traffic situations.\",\n \"Title: Cross-region traffic prediction for China on OpenStreetMap.\\nYear: 2016\\n\\nAbstract: OpenStreetMap (OSM) is a free, open-source and popular mapping service. However, due to various reasons, it doesn't offer live traffic information or traffic prediction for China. This paper presents an approach and a system to learn a prediction model from graphical traffic condition data provided by Baidu Map, which is a commercial, close-source map provider in China, and apply the model on OSM so that one can predict the traffic conditions with nearly 90% accuracy in various parts of Shanghai, China, even though no traffic data is available for that area from Baidu Map. This novel system can be useful in urban planning, transportation dispatching as well as personal travel planning.\",\n \"Title: Optimizing Propagation Network of Certificate Revocation in VANET with Meet-Table.\\nYear: 2016\\n\\nAbstract: Certificate is widely used in VANET (Vehicle Ad hoc Network) to make it secure. But when a certificate is untrustworthy, it must be revoked. Propagation of certificate revocation information in VANET is not only essential but also challenging. In order to optimizing the propagation network of certificate revocation, Meet-Table is proposed. The Meet-Table of a vehicle records vehicles it met in the past. With the help of Meet-Table, a vehicle only needs to broadcast CRL (Certificate Revocation List) related to vehicles in its Meet-Table, so the network communication complexity and storage complexity of CRL in VANET can be optimized. Both of the two complexities are discussing formally. Comparing the schema proposed in this paper with CRL in classical PKI, road side unit broadcasting and epidemic fashion shows that the Meet-Table can significantly reduce the complexity of CRL propagation.\",\n \"Title: A Scalable and Adaptable Multiple-Place Foraging Algorithm for Ant-Inspired Robot Swarms.\\nYear: 2016\\n\\nAbstract: Individual robots are not effective at exploring large unmapped areas. An alternate approach is to use a swarm of simple robots that work together, rather than a single highly capable robot. The central-place foraging algorithm (CPFA) is effective for coordinating robot swarm search and collection tasks. Robots start at a centrally placed location (nest), explore potential targets in the area without global localization or central control, and return the targets to the nest. The scalability of the CPFA is limited because large numbers of robots produce more inter-robot collisions and large search areas result in substantial travel costs. We address these problems with the multiple-place foraging algorithm (MPFA), which uses multiple nests distributed throughout the search area. Robots start from a randomly assigned home nest but return to the closest nest with found targets. We simulate the foraging behavior of robot swarms in the robot simulator ARGoS and employ a genetic algorithm to discover different optimized foraging strategies as swarm sizes and the number of targets are scaled up. In our experiments, the MPFA always produces higher foraging rates, fewer collisions, and lower travel and search time compared to the CPFA for the partially clustered targets distribution. The main contribution of this paper is that we systematically quantify the advantages of the MPFA (reduced travel time and collisions), the potential disadvantages (less communication among robots), and the ability of a genetic algorithm to tune MPFA parameters to mitigate search inefficiency due to less communication.\",\n \"Title: Acoustic holography — A robot application\\nYear: 2016\\n\\nAbstract: Acoustic holography is a technique to visualize the sound field propagating from a sound source. It is used to analyse and locate sources of noise, and even allows to predict the propagation of sound in the environment. However, this technique involves simultaneous measurements of up to 256 microphones, arranged in an array. We propose an alternative approach with 4 or less microphones which are re-positioned using an articulated robot arm. Provided the measurement conditions are stable, this alternative approach with consecutive measurements allows to make use of acoustic holography to investigate various sources of noise. The case of fan noise is demonstrated where the focus is put on practical aspects conducting near-field acoustic holography experiments using a robot arm, as well as post-processing measurement data. As a result, 2 complimenting techniques, static and dynamic near-field acoustic holography, are introduced and their merits are discussed.\",\n \"Title: Research On Data Mining Service And Its Application Case In Complex Industrial Process\\nYear: 2017\\n\\nAbstract: In today's competitive market, companies need to apply different data mining techniques in order to make more intelligent, accurate business decisions. Data mining technology from industrial big data can provide a more effective help for decision-making of enterprises' innovative design. This paper explores the advantages of data mining services, and presents a SOA-based data mining framework applied to non-expert data miners which can be treated as Software-as-a-Service including data uploading, data cleaning, data mining algorithm, OLAP and so on. As an example, a hybrid reasoning mechanism for intelligent design decision based on DM and its application in complex textile industry are also discussed.\",\n \"Title: Exploring the potential climate change impact on urban growth in London by a cellular automata-based Markov chain model.\\nYear: 2018\\n\\nAbstract: Urbanization has become a global trend under the combined influence of population growth, socioeconomic development, and globalization. Even though recent urban planning in London has been more deliberate, the relationships between climate change and urban growth in the context of economic geography are still somewhat unclear. This study relies on rainfall prediction with the aid of the Statistical DownScaling Model (SDSM), which provides the statistical foundation for future flooding potential within the urban space of London while considering major socioeconomic policies related to land use management. These SDSM findings, along with current land use policies, were included as other factors or constraints in a cellular automata-based Markov Chain model to simulate and predict land use changes in London for 2030 and 2050. Two scenarios with the inclusion and exclusion of flood impact factor, respectively, were applied to evaluate the impact of climate change on urban growth. Findings indicated: (1) mean monthly projected precipitation derived by SDSM is expected to increase for the year 2030 in London, which will affect the flooding potential and hence the area of open space; (2) urban and open space are expected to increase >16 and 20km2 (in percentage of 1.51 and 1.92 compared to 2012) in 2030 and 2050, respectively, while agriculture is expected to decrease significantly due to urbanization and climate change; (3) the inclusion of potential flood impact induced from the future precipitation variability drives the development toward more open space and less urban area.\",\n \"Title: Feature-Based Carbon Emission Quantitation Strategy For The Part Machining Process\\nYear: 2018\\n\\nAbstract: As global warming is becoming remarkably serious, the issue of low-carbon manufacturing has attracted numerous researchers' attention. Meanwhile, manufacturing industries require the carbon emission data of their products to cope with the coming carbon policy such as carbon labelling. Since products are made of parts, one of the major difficulties is the lack of a well-established approach to obtain the carbon emissions of machining a part. In this paper, a carbon emission quantitation strategy is proposed to quantify the overall carbon emissions of a part machining process. In the quantitation strategy, firstly, the calculation models for various types of carbon emissions are presented to analyse the carbon footprint. A formalised approach is then proposed to quantify the overall carbon emissions by designing a c-PBOM (carbon emissions-Process Bill of Material) based on machining features. Particularly, in order to reduce the computation complexity and clarify the computation process, a c-PBOM is established to support the quantitation strategy by decomposing a part into an aggregation of machining features. In addition, the machining process is considered as a cooperation of the energy consumers decomposed from the machine tool. Finally, the strategy is applied in the machining of a bearing seat. The results show it can be used to predict the carbon emissions for a part machining process conveniently and efficiently, which would provide a data base for the research of low-carbon process planning and scheduling.\",\n \"Title: Application of Time-Domain Full Waveform Inversion to Cross-Hole Radar Data Measured at Xiuyan Jade Mine, China.\\nYear: 2018\\n\\nAbstract: Xiuyan Jade, produced in Xiuyan County, Liaoning Province, China is one of the four famous jade in China. King Jade, which is deemed the largest jade body of the world, was broken out from a hill. The local government planned to build a tourism site based on the jade culture there. The purpose of the investigation was to evaluate the stability of subsurface foundation, and the possible positions of mined-out zones to prevent the further rolling of the jade body. Cross-hole radar tomography is the key technique in the investigation. Conventional travel time and attenuation tomography based on ray tracing theory cannot provide high-resolution images because only a fraction of the measured information is used in the inversion. Full-waveform inversion (FWI) can provide high-resolution permittivity and conductivity images because it utilizes all the information provided by the radar signals. We deduce the gradient expression of the time-domain FWI with respect to the permittivity and conductivity using a method that is different from that of the previous work and realize the FWI algorithm that can simultaneously update the permittivity and conductivity by using the conjugate gradient method. Inverted results from synthetic data show that time-domain FWI can significantly improve the resolution compared with the ray-based tomogram methods. FWI can distinguish targets that are as small as one-half to one-third wavelength and the inverted physical values are closer to the real ones than those provided by the ray tracing method. We use the FWI algorithm to the field data measured at Xiuyan jade mine. Both the inverted permittivity and conductivity can comparably delineate four mined-out zones, which exhibit low-permittivity and low-conductivity characteristics. Furthermore, the locations of the interpreted mined-out zones are in good agreement with the existing mining channels recorded by geological data.\",\n \"Title: Sequential Context Encoding for Duplicate Removal.\\nYear: 2018\\n\\nAbstract: Duplicate removal is a critical step to accomplish a reasonable amount of predictions in prevalent proposal-based object detection frameworks. Albeit simple and effective, most previous algorithms utilize a greedy process without making sufficient use of properties of input data. In this work, we design a new two-stage framework to effectively select the appropriate proposal candidate for each object. The first stage suppresses most of easy negative object proposals, while the second stage selects true positives in the reduced proposal set. These two stages share the same network structure, i.e., an encoder and a decoder formed as recurrent neural networks (RNN) with global attention and context gate. The encoder scans proposal candidates in a sequential manner to capture the global context information, which is then fed to the decoder to extract optimal proposals. In our extensive experiments, the proposed method outperforms other alternatives by a large margin.\",\n \"Title: A Kinect-Based Approach for 3D Pavement Surface Reconstruction and Cracking Recognition.\\nYear: 2018\\n\\nAbstract: Pavement surface distress conditions are critical inputs for quantifying roadway infrastructure serviceability. Numerous computer-aided automatic examination techniques have been deployed for pavement distress condition assessments, such as digital image processing methods. However, their effectiveness and applicability are impeded due to information losses in 2-D image combination processes or ex...\",\n \"Title: Graph-Based Knowledge Reuse For Supporting Knowledge-Driven Decision-Making In New Product Development\\nYear: 2017\\n\\nAbstract: Pre-existing knowledge buried in manufacturing enterprises can be reused to help decision-makers develop good judgements to make decisions about the problems in new product development, which in turn speeds up and improves the quality of product innovation. This paper presents a graph-based approach to knowledge reuse for supporting knowledge-driven decision-making in new product development. The paper first illustrates the iterative process of knowledge-driven decision-making in new product development. Then, a novel framework is proposed to facilitate this process, where knowledge maps and knowledge navigation are involved. Here, OWL ontologies are employed to construct knowledge maps, which appropriately capture and organise knowledge resources generated at various stages of product lifecycle; the Personalised PageRank algorithm is used to perform knowledge navigation, which finds the most relevant knowledge in knowledge maps for a given problem in new product development. Finally, the feasibility and effectiveness of the proposed approach are demonstrated through a case study and two performance evaluation experiments.\",\n \"Title: IRelics: Designing a Tangible Interaction Platform for the Popularization of Field Archaeology\\nYear: 2019\\n\\nAbstract: We present IRelics, a tangible interaction platform for the popularization of field archeology. IRelics allows users to experience archaeological field work activities as a serious game by using a set of tangible tools. We developed an innovative LWIR (Long Wavelength Infrared Rays) sensing system, which implements the design of tangible tools that provide real manipulation experiences. By interacting with IRelics, a player may experience different archaeological activities such as excavation and cleaning. We conducted two observations to evaluate the usability and effectiveness at archeology popularizing. Findings suggest that the IRelics platform can enhance the engagement of the participants by providing a positive and interactive environment while teaching them unfamiliar knowledge.\",\n \"Title: Multiple-place swarm foraging with dynamic depots.\\nYear: 2018\\n\\nAbstract: Teams of robots can be organized to collectively complete complex real-world tasks, for example collective foraging in which robots search for, pick up, and drop off targets in a collection zone. In the previously proposed central-place foraging algorithm (CPFA), foraging performance decreases as swarm size and search areas scale up: more robots produce more inter-robot collisions and larger search areas produce longer travel distances. We propose the multiple-place foraging algorithm with dynamic depots () to address these problems. Depots are special robots which are initially distributed in the search area and can carry multiple targets. Depots move to the centroids of the positions of local targets recently detected by robots. The spatially distributed design reduces robot transport time and reduces collisions among robots. We simulate robot swarms that mimic foraging ants using the strategy, employing a genetic algorithm to optimize their behavior in the robot simulator ARGoS. Robots using the find and collect targets faster than both the CPFA and the static MPFA. outperforms the static MPFA even when the static depots are optimally placed using global information, and it outperforms the CPFA even when the dynamic depots deliver targets to a central location. Further, the scales up more efficiently, so that the improvement over the CPFA and the static MPFA is even greater in large (50 50 m) areas. Including simulated error reduces foraging performance across all algorithms, but the MPFA still outperforms the other approaches. Our work demonstrates that dispersed agents that dynamically adapt to local information in their environment provide more flexible and scalable swarms. In addition, we illustrate a path to implement the in the physical robot swarm of the NASA Swarmathon competition.\",\n \"Title: Generating Significant Subassemblies From 3d Assembly Models For Design Reuse\\nYear: 2018\\n\\nAbstract: Significant subassemblies are defined as the reusable regions of pre-existing 3D assembly models. A significant subassembly has great significances for design reuse as it aggregates abundant knowledge in a vivid 3D CAD model and enables designers to reuse existing mature designs from a high-level perspective. Consequently, this paper contributes to significant subassembly generation from pre-existing 3D assembly models for design reuse. The paper first gives an explicit definition of significant subassemblies and further explores the multilevel knowledge embedded in these significant subassemblies. Based on the above definition and multilevel knowledge, a knowledge-based approach is then proposed for significant subassembly generation, which includes three phases: (1) identifying candidate subassemblies with high cohesion inside and low coupling outside using the Markov clustering process; (2) removing normal candidate subassemblies with low reusability and less information, and generating filtered subassemblies using the proposed assembly frequency - inverse mean subassembly frequency based scheme; and (3) determining significant subassemblies by measuring the complexity of the filtered subassemblies. Finally, a computer numerical control honing machine model is taken as an application example to demonstrate the effectiveness of the proposed approach.\",\n \"Title: Application of Mathematical Morphological Filtering to Improve the Resolution of Chang'E-3 Lunar Penetrating Radar Data.\\nYear: 2019\\n\\nAbstract: As one of the important scientific instruments of lunar exploration, the Lunar Penetrating Radar (LPR) onboard China's Chang'E-3 (CE-3) provides a unique opportunity to image the lunar subsurface structure. Due to the low-frequency and high-frequency noises of the data, only a few geological structures are visible. In order to better improve the resolution of the data, band-pass filtering and empirical mode decomposition filtering (EMD) methods are usually used, but in this paper, we present a mathematical morphological filtering (MMF) method to reduce the noise. The MMF method uses two structural elements with different scales to extract certain scale-range information from the original signal, at the same time, the noise beyond the scale range of the two different structural elements is suppressed. The application on synthetic signals demonstrates that the morphological filtering method has a better performance in noise suppression compared with band-pass filtering and EMD methods. Then, we apply band-pass filtering, EMD, and MMF methods to the LPR data, and the MMF method also achieves a better result. Furthermore, according to the result by MMF method, three stratigraphic zones are revealed along the rover's route.\",\n \"Title: Dam Leakage Detection by Borehole Radar: A Case-History Study.\\nYear: 2019\\n\\nAbstract: A borehole radar investigation was performed at the Sanzuodian reservoir, Chifeng, China to assess possible leakage paths located in the deep dam foundation. The key methodologies used include both single-hole reflection and cross-hole radar tomography, which make a high-resolution identification of the hydraulic connection paths between upstream and downstream sides possible. The leakage paths are characterized by direct wave loss due to high electromagnetic attenuation in the single-hole reflection profile and the nearly horizontal-banded low-velocity zone in the cross-hole velocity tomography due to possible large internal erosion. Meanwhile, some small structures inside the dam, including the core wall thickness changing point, the connecting point between asphalt and concrete walls, and the contacting interface between the dry and the water-saturated formations can be identified from the single-hole reflection profile clearly. Interpreted leakage paths are proven by the water flow measurement. Borehole radar is a useful high-resolution tool, suitable for deep leakage detection and evaluation.\",\n \"Title: A Novel Graphene Double-Balanced Passive Mixer\\nYear: 2018\\n\\nAbstract: A four-graphene-field-effect-transistor integrated double-balanced mixer is presented in this paper. With 1.59 GHz and 1.61 GHz frequency input, the mixed signals feature an IIP3 of 12.7 dBm, which benefited from the linearity of graphene field effect transistors (GFETs). Due the passive nature of the proposed resistive mixer topology, it has zero power consumption. Size of the chip is smaller than 200 mu m x 200 mu m, integrated by two-metal-layer CMOS back-end-of-line technology. The mixer operates in gigahertz frequency range, consistent with large-signal compact model based simulations.\",\n \"Title: Linear Prediction-Based DOA Estimation for Directional Borehole Radar 3-D Imaging\\nYear: 2019\\n\\nAbstract: Directional borehole radar (BR) 3-D imaging is a challenging problem due to its limited observation space within a borehole. We present a linear prediction (LP)-based direction-of-arrival (DOA) estimation and a migration-based 3-D imaging algorithm for the directional BR, which is composed of a transmitting antenna and a uniform circular array including four small receiving antennas. Only the azimuth is estimated, while the elevation and the distance are included in the imaging process. LP is a useful tool for DOA estimation in the radar domain, but a single linear array (LA) has azimuth ambiguity in DOA estimation. The four receiving antennas are treated as two orthogonal uniform LAs. The combination of two arrays removes the ambiguity in DOA estimation. In addition, the moving window and the threshold-based estimation increase the calculation efficiency. According to the estimated azimuth angles, the measured signal at each depth is decomposed to the corresponding directions. Therefore, there is a time-series signal in each direction at each depth. After processing the measured signals at all depths, we obtain a 3-D data set that can be used for horizontal- and radial vertical-section displays. Then, the radial vertical-section data are processed by migration which transforms the time domain signal into a wavefield-based 3-D image. Simulated data from a fracture model are used to validate the algorithm, and the reconstructed image can reveal the real model well. It is concluded that the novel method we propose is an effective one with real-time processing capability.\",\n \"Title: Partial Approximate Controllability for Linear Stochastic Control Systems\\nYear: 2019\\n\\nAbstract: This paper is devoted to studying controllability problems of linear stochastic control systems with controls only in the drift terms. It is well known that such a system is not exactly controllable. We first construct an example to show that it is also not approximately controllable under some natural condition. Next we introduce the notion of partial approximate controllability and reveal that it is equivalent to some weak unique continuation property of backward stochastic evolution equations. Then we prove that this kind of unique continuation property holds. Finally, two examples concerning controlled stochastic parabolic and stochastic Schrodinger equations are presented.\",\n \"Title: An Integrated Decision-Making Approach On Cutting Tools And Cutting Parameters For Machining Features Considering Carbon Emissions\\nYear: 2019\\n\\nAbstract: Cutting parameters and cutting tools are vital in process planning. Reasonable decision-making of cutting parameters and cutting tools could reduce the processing carbon emissions, time, and cost in machining process. Traditionally, cutting parameter optimization is performed with a preset cutting tool, which limits the potential for carbon emissions savings. In order to globally reduce carbon emissions of machining featuresof parts, this paper provides a new methodology for the integrated optimisation of cutting parameters and cutting tools, where the optimal cutting parameters and cutting tools are identified simultaneously to balance the minimum processing carbon emissions, cost and time for a machining feature of parts. Firstly, a carbon emissions model considering multiple cutting tool flexibilities and corresponding cutting parameters is analyzed and established for a machining feature of parts. Then a multi-objective integration optimisation model of cutting tools and cutting parameters is presented. Thirdly, a NSGA-II algorithm is correspondingly designed to solve the proposed integrated model. Finally, case studies are used to verify the proposed approach. The comparative results show that: i) The integration approach can save more carbon emissions compared with traditional methods; ii) The integrated optimisation methodology can strike a balance among minimum processing carbon emissions, time and cost.\",\n \"Title: Cognition differences and improvement countermeasures of non-technical medical services based on grey correlation analysis.\\nYear: 2019\\n\\nAbstract: Purpose The purpose of this paper is to explore the rationality differences of cognition of non-technical medical services in different groups, and to provide countermeasures for improving non-technical medical services. Design/methodology/approach Literature analysis, expert interviews, questionnaire survey and frequency analysis were taken to reveal the influencing factors of non-technical medical services. Grey correlation methods were taken to compare the rationality differences of cognition of non-technical medical services by analysis influencing factors' scores marked by different groups. Findings A total of 12 influencing factors of non-technical medical services were obtained, including doctor's working career, doctor's strict implementation of medical treatment norms and medication guidelines, doctor's service awareness, etc. And rationality differences of cognition of non-technical medical services were confirmed as follows: the doctors' cognition was more reasonable compared with patients; the women's cognition was more reasonable compared with men; the lower aged groups' cognition was more reasonable compared with higher aged groups; and people with doctoral degree had a less reasonable cognition compared with others. Originality/value The authors systematically discussed the cognition differences of non-technical medical services among different people, and provided some countermeasures reasonably.\",\n \"Title: Analysis of patients' attitudes towards medical service prices in different regions based on grey relational theory.\\nYear: 2019\\n\\nAbstract: Purpose The purpose of this paper is to understand the attitude of patients towards the current medical service price and the effect of policy implementation, and explore the existing problems of the current medical service price policy in the region in order to provide a research basis for the dynamic adjustment mechanism of the medical service price. Design/methodology/approach Literature analysis and expert interviews are used to design the questionnaire of the dynamic adjustment of medical service price formation mechanism. A convenient sampling method is used to extract data of 600 patients from the five areas, namely Beijing, Tianjin, Hebei, Shandong and Liaoning, on-site to fill out the paper-based questionnaire and electronic questionnaire. The grey relational analysis is used to explore the difference in the attitudes of patients towards the price of the medical service. Combined with the research results and expert interview results, some improvement suggestions related to the current price policy of medical service in five areas are put forward. Findings The overall average score of respondents in the five areas, namely Beijing, Tianjin, Hebei, Shandong and Liaoning, is found to be 3.861. In terms of surgical operation fee and examination fee, the average score is higher than 4, i.e. 4.097 and 4.011, respectively, indicating relatively high nodes. According to grey relevancy sorting, the correlation between the health service price attitude and the overall score in the five regions is in the following order: Shandong > Tianjin > Beijing > Liaoning > Hebei. Originality/value In this study, patients' attitude towards the current price of medical services in their local areas, Beijing, Tianjin, Hebei, Shandong and Liaoning, is investigated in order to explore the existing problems of medical service price reform and thus provide the basis for further improvement in the medical service price policy.\",\n \"Title: The investigation and analysis of the current situation of medical service price cognition of China with grey relational analysis theory.\\nYear: 2019\\n\\nAbstract: Purpose Through a questionnaire survey, the purpose of this paper is to understand and analyse the cognitions of medical service price of medical workers in various regions of China, and discuss the policy suggestions on the price dynamic adjustment of medical service. Design/methodology/approach The authors conducted a questionnaire survey on the cognition of medical service price medical workers in various regions of China, and then the grey relational analysis theory is used to analyse the data obtained from the questionnaire survey. Findings The investigation and analysis shows some cognitions of hospital workers on the price of medical services in various regions in China, the authors analyse the results of grey relational analysis and come up with suggestions for relevant departments. Research limitations/implications Although a plenty of research on the current situation of medical service price cognition of China is discussed in the paper, it is not complete; thus, a large amount of information needs to be consulted further. The data obtained from the questionnaire are less used and the utilisation rate is lower, which may result in one-sided results and need further investigation. Practical implications Through the investigation and analysis, the authors can determine about the implementation of medical service prices in various parts of China from the perspective of hospital workers to a certain degree, and try to explore the relevant policy recommendations for the dynamic adjustment of medical service prices. Social implications The price of medical services refers to the fees for registration, diagnosis, inspection, surgery, nursing and medicine. In a narrow sense, the price of medical services refers to the standard of charge for medical services except drugs. This paper mainly refers to the narrow sense. As one of the important means and methods for the government to control the medical service market, medical service price is also an important basis for the economic source of medical institutions. The adjustment of medical service price is related to the interests of all aspects of society. Originality/value Medical service price is an important basis for the economic source of medical institutions, the adjustment of medical service price is related to the interests of all aspects of society and it is a hot issue of social concern. Through the investigation and analysis, the authors use grey relational analysis to know about the medical service prices in various parts of China from the perspective of hospital workers to a certain degree, and try to explore the relevant policy recommendations for the dynamic adjustment of medical service prices.\",\n \"Title: On-Path Caching Based On Content Relevance In Information-Centric Networking\\nYear: 2021\\n\\nAbstract: The Internet of things (IoT) is a new network concept. Based on the Internet, the idea of connecting everything is proposed, which is likely to become the development direction of computer and communication in the future. Meanwhile, as a disruptive new communication network model, Information-Centric Network (ICN) has become a hot spot in the field of future network architecture research in recent years. ICN is informationcentric, and uses the name of the information to implement data identification, retrieval, and routing and forwarding. The information centric network uses the cache as a built-in structure, and nodes store all the data that flows by default, so that subsequent requests can be responded to as soon as possible. In the actual network, the spread and trend of an information constantly change with time, and the popularity of the information is different in different time periods. However, the existing ICN native caching mechanism ignores the correlation between contents, and the existing relevant research makes insufficient use of content relevance. In this paper may exist a certain correlation between nodes have access to the content of the facts, we design a path cache method based on the correlation content, by discovering target content and the correlation between nodes store content, at the same time considering the node position in the path, make caching decisions, make the cache memory more efficient. The feasibility and effectiveness of the proposed method are verified by simulation experiments under different parameters.\",\n \"Title: The Dynamic Analysis Of A Novel Reconfigurable Cubic Chaotic Map And Its Application In Finite Field\\nYear: 2021\\n\\nAbstract: Dynamic degradation occurs when chaotic systems are implemented on digital devices, which seriously threatens the security of chaos-based pseudorandom sequence generators. The chaotic degradation shows complex periodic behavior, which is often ignored by designers and seldom analyzed in theory. Not knowing the exact period of the output sequence is the key problem that affects the application of chaos-based pseudorandom sequence generators. In this paper, two cubic chaotic maps are combined, which have symmetry and reconfigurable form in the digital circuit. The dynamic behavior of the cubic chaotic map and the corresponding digital cubic chaotic map are analyzed respectively, and the reasons for the complex period and weak randomness of output sequences are studied. On this basis, the digital cubic chaotic map is optimized, and the complex periodic behavior is improved. In addition, a reconfigurable pseudorandom sequence generator based on the digital cubic chaotic map is constructed from the point of saving consumption of logical resources. Through theoretical and numerical analysis, the pseudorandom sequence generator solves the complex period and weak randomness of the cubic chaotic map after digitization and makes the output sequence have better performance and less resource consumption, which lays the foundation for applying it to the field of secure communication.\",\n \"Title: Multi-Actor-Attention-Critic Reinforcement Learning for Central Place Foraging Swarms\\nYear: 2021\\n\\nAbstract: Multiple agents with relatively low cost, decentralized control, and robustness have the advantages of completing a foraging task more efficiently than a single advanced robot. Despite many foraging algorithms are efficient in multiple robot systems, most are pre-designed or not very adaptive to different environments since they have to evolve the parameters of the foraging algorithm in each different environment. Besides, designing an efficient collision avoidance strategy for multiple agents is a challenge. Addressing these issues, we introduce the multi-actor-attention-critic(MAAC) reinforcement learning method into the multiple foraging agents. We train the foraging strategy for multiple simulated agents. We compare our approach with existing foraging algorithms for multiple robots, the Central Place Foraging Algorithm (CPFA) and the Distributed Deterministic Spiral Algorithm (DDSA). Experimental results demonstrate that our approach outperforms the two algorithms. Also, we illustrate that our approach has a better performance in avoiding obstacles and adapting to different environments.\",\n \"Title: Multiple-Place Swarm Foraging with Dynamic Robot Chains\\nYear: 2021\\n\\nAbstract: The goal of foraging robot swarms is to search and deliver resources to a specific central collection zone quickly. In the previously proposed multiple-place foraging algorithm with dynamic depots, foraging performance decreases as search areas and swarm sizes increase: depots need to travel long distances to deliver resources to the center, and more robots produce more congestion on their journeys. We propose a novel extension to the multiple-place foraging in which multiple robot chains are deployed dynamically. Each robot chain connects a foraging location to the central collection zone. Instead of delivering resources by a single robot, resources are passed on robot chains from foraging locations to the center directly such that congestion near the central collection zone can be avoided. Dynamic robot chains can also relocate themselves to get closer to the resources while avoiding obstacles. We simulate our robot swarms in the robot simulator ARGoS. Our experiments show that robots using the MPFA with dynamic chains outperform the MPFA with dynamic depots and have less congestion.\",\n \"Title: Volumetric segmentation of white matter tracts with label embedding\\nYear: 2022\\n\\nAbstract: •We propose a network that performs volumetric segmentation of white matter tracts.•The tract correlation is exploited with label embedding in the network design.•Our method was validated on public and private datasets under various settings.•The segmentation quality is improved compared with competing methods.•The improvement is more prominent for challenging tracts in challenging scenarios.\",\n \"Title: CADRE: A Cascade Deep Reinforcement Learning Framework for Vision-Based Autonomous Urban Driving.\\nYear: 2022\\n\\nAbstract: Vision-based autonomous urban driving in dense traffic is quite challenging due to the complicated urban environment and the dynamics of the driving behaviors. Widely-applied methods either heavily rely on hand-crafted rules or learn from limited human experience, which makes them hard to generalize to rare but critical scenarios. In this paper, we present a novel CAscade Deep REinforcement learning framework, CADRE, to achieve model-free vision-based autonomous urban driving. In CADRE, to derive representative latent features from raw observations, we first offline train a Co-attention Perception Module (CoPM) that leverages the co-attention mechanism to learn the inter-relationships between the visual and control information from a pre-collected driving dataset. Cascaded by the frozen CoPM, we then present an efficient distributed proximal policy optimization framework to online learn the driving policy under the guidance of particularly designed reward functions. We perform a comprehensive empirical study with the CARLA NoCrash benchmark as well as specific obstacle avoidance scenarios in autonomous urban driving tasks. The experimental results well justify the effectiveness of CADRE and its superiority over the state-of-the-art by a wide margin.\",\n \"Title: A transfer learning approach to few-shot segmentation of novel white matter tracts\\nYear: 2022\\n\\nAbstract: •We explore knowledge transfer for few-shot segmentation of novel WM tracts.•A model pretrained for segmenting existing WM tracts is given.•We derive a better network initialization for segmenting novel WM tracts.•Data augmentation is further applied with tract-aware image mixing.•Our method was validated on public and private datasets under various settings.\",\n \"Title: Assessing the Effects of Induced Field Rotation on Water Ice Detection of Tianwen-1 Full-Polarimetric Mars Rover Penetrating Radar\\nYear: 2022\\n\\nAbstract: China's first Mars probe Tianwen-1 has successfully landed on the southern Utopia Planitia of Mars on May 15, 2021. The Zhurong rover is first equipped with a full-polarimetric Mars Rover Penetrating Radar (FP-RoPeR) system, aiming to map the subsurface fine structure and to find the potential underground water ice. However, different from the previous water ice detection of orbital radar, the FP-RoPeR signals will be affected by the induced field rotation (IFR) if electromagnetic (EM) waves propagate through rough interfaces. Therefore, in this article, we assess the IFR effects from rough interfaces on the circular polarization ratio (CPR) response of FP-RoPeR data, which is a significant parameter for water ice detection. The theoretical computation and numerical validation indicate that the depth, the number of rough interfaces, and relative permittivity are three vital parameters that affect the IFR effects; depth plays a more important role than the other two for FP-RoPeR system. The CPR estimation result will be with greater error in the shallow region (0-1 m). The relative error in the region of depth greater than 1 m can be guaranteed to be under 10%.\",\n \"Title: O&O: A DIY toolkit for designing and rapid prototyping olfactory interfaces\\nYear: 2022\\n\\nAbstract: ABSTRACTConstructing olfactory interfaces on demand requires significant design proficiency and engineering effort. The absence of powerful and convenient tools that reduced innovation complexity posed obstacles for future research in the area. To address this problem, we proposed O&O, a modular olfactory interface DIY toolkit. The toolkit consists of: (1) a scent generation kit, a set of electronics and accessories that supported three common scent vaporization techniques; (2) a module construction kit, a set of primitive cardboard modules for assembling permutable functional structures; (3) a design manual, a step-by-step design thinking framework that directs the decision-making and prototyping process. We organized a formal workshop with 19 participants and four solo DIY trials to evaluate the capability of the toolkit, the overall user engagement, the creations in both sessions, and the iterative suggestions. Finally, design implications and future opportunities were discussed for further research.\",\n \"Title: Shape-driven lightweight CNN for finger-vein biometrics\\nYear: 2022\\n\\nAbstract: Finger-vein recognition has been widely explored for biometrics security over the past two or three decade. Its size and characteristics against presentation attacks make it suitable for various commercial, governmental and forensics applications. As with other biometric traits, finger-vein recognition approaches mainly depend on well-engineering feature descriptors and recently, more deep learning (DL) models have been designed to achieve high-performance biometrics. However, the existing DL approaches usually employ the neural networks with increasing layers and parameters, which inevitably leads to an increase in memory consumption and algorithm complexity. Besides, all the vein recognition networks use square filters, which are influenced by network designed for object detection and classification. In this paper, two network design issues for finger-vein recognition are explored: shallow network using rectangular filters and lightweight semi-pretrained network. The exhaustive experiments on three benchmark databases HKPU, FV-USM and SDUMLA demonstrate that rectangular filters outperform square filters for DL-based finger-vein recognition, and the lightweight semi-pretrained network also outperforms non-pretrained network.\",\n \"Title: Simulation of Borehole Radar Responses to Rough Fractures Based on 3-D Conformal FDTD\\nYear: 2022\\n\\nAbstract: Borehole radar is a powerful tool for detecting subsurface fractures. Fracture modeling and numerical simulation are essential means to study fracture detectability. In this article, we first propose a method to construct a single fracture model, which combines the Baecher disk model and random rough surface and includes features, such as roughness, pinch-out, and irregularity. As the precise description of the fracture raises the requirement for accuracy of the simulation algorithm, the 3-D conformal finite-difference time-domain (CFDTD) method is used in this work. Numerical simulations of a sphere and rough fractures show that the CFDTD has higher calculation accuracy than conventional FDTD. Then, we analyzed how the fractures with different roughness affect the electromagnetic wave response. It is found that as the fracture surface becomes rougher, the wave scattered by it becomes stronger, more fracture contour-related information is obtained, and the fracture morphology is recovered better. Combined with accurate fracture modeling and high-precision numerical simulation, the electromagnetic response characteristics of different forms of fractures are obtained, which provides a basis for the accurate detection and interpretation of fractures in the future.\",\n \"Title: Environmental assisted cracking and strength attenuation effect computing on the mechanical properties of casing steel P110 for industrial revolution 5.0 applications in sour well environments\\nYear: 2022\\n\\nAbstract: Casing steel is prone to reduced mechanical properties and occurred environmentally assisted cracking finally in sour well environment containing H2S and CO2. The paper mainly researched on the relationship between mechanical properties and hydrogen permeation, exposed casing steel P110 to air, NACE A solution, and simulated formation water containing H2S and CO2 with a stress of 80% yield strength at 60 °C for 168 h, testing its mechanical properties shown strain-aging phenomenon and ductile–brittle transition. The lowest mechanical properties are occurred in the sour well environment, its yield strength, and tensile strength, respectively, reduction 5.0% and 4.7%, while a loss of 41.4% in fracture toughness. With temperature increased from 25 to 60 °C, the hydrogen diffusion coefficient increases by 1.59 times, and there is a mutation in mechanical properties of P110, when the hydrogen diffusion coefficient is 1.64 × 10–4 cm2/s and the subsurface hydrogen concentration is.1.653 × 10–5%. The steel P110 has shown a ductile fracture with toughnest exposed in the air and shown cleavage fracture characteristics exposed to sour environments, indicating that hydrogen permeation has changed the fracture mode from ductile to brittle. This method can be used to test and compute the strength attenuation effect of casing P110 serviced in sour well environments.\",\n \"Title: Particle Swarm Optimization-Based Variational Mode Decomposition for Ground Penetrating Radar Data Denoising\\nYear: 2022\\n\\nAbstract: Ground Penetrating Radar (GPR) has become a widely used technology in geophysical prospecting. The Variational Mode Decomposition (VMD) method is a fully non-recursive signal decomposition method with noise robustness for GPR data processing. The VMD algorithm determines the central frequency and bandwidth of each Intrinsic Mode Function (IMF) by iteratively searching for the optimal solution of the variational mode and is capable of adaptively and effectively dividing the signal in the frequency domain into the many IMFs. However, the penalty parameter alpha and the number of IMFs K in VMD processing are determined depending on manual experience, which are important parameters affecting the decomposition results. In this paper, we propose a method to automatically search the parameters alpha and K optimally by Particle Swarm Optimization (PSO) algorithm. Then the signal-to-noise ratio (SNR) and root-mean-square error (RMSE) are used to judge the best superposition of the IMFs for data reconstruction, and the process is data-driven without human subjective intervention. The proposed method is used to process the field data, and the reconstruction data show that this innovative VMD processing can effectively improve the SNR and highlight the target reflections, even some targets not found in pre-processing are also revealed.\",\n \"Title: Channel Condition and Outage Performance of Mode-Division-Multiplexing Enabled MIMO System With Zero-Forcing Receiver\\nYear: 2022\\n\\nAbstract: Reusing the widely deployed multimode fibers (MMFs) in buildings to transmit multiple-input multiple-output (MIMO) signals via mode-division multiplexing (MDM) is an attractive solution to provide low-cost indoor wireless coverage. However, due to the random mode coupling, MMF channel varies over time. In this letter, the MDM-based MMF MIMO channel condition for different fiber lengths is studied. Next, the influence of the fluctuation of channel condition on the outage performance of the MIMO system with zero-forcing receiver is analyzed, in terms of information-theoretic capacity and practical error probability. Finally, by using adaptive coded modulation (according to channel condition), the MDM-based \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$3 \\\\times 3$ </tex-math></inline-formula>\\n MIMO channel achieves up to 8.62 bit/s/Hz spectral efficiency with 10% outage probability.\",\n \"Title: One-Shot Segmentation of Novel White Matter Tracts via Extensive Data Augmentation\\nYear: 2022\\n\\nAbstract: Deep learning based methods have achieved state-of-the-art performance for automated white matter (WM) tract segmentation. In these methods, the segmentation model needs to be trained with a large number of manually annotated scans, which can be accumulated through- out time. When novel WM tracts i.e., tracts not included in the existing annotated WM tracts are to be segmented, additional annotations of these novel WM tracts need to be collected. Since tract annotation is time-consuming and costly, it is desirable to make only a few annotations of novel WM tracts for training the segmentation model, and previous work has addressed this problem by transferring the knowledge learned for segmenting existing WM tracts to the segmentation of novel WM tracts. However, accurate segmentation of novel WM tracts can still be challenging in the one-shot setting, where only one scan is annotated for the novel WM tracts. In this work, we explore the problem of one-shot segmentation of novel WM tracts. Since in the one-shot setting the annotated training data is extremely scarce, based on the existing knowledge transfer framework, we propose to further perform extensive data augmentation for the single annotated scan, where synthetic annotated training data is produced. We have designed several different strategies that mask out regions in the single annotated scan for data augmentation. To avoid learning from potentially conflicting information in the synthetic training data produced by different data augmentation strategies, we choose to perform each strategy separately for network training and obtain multiple segmentation models. Then, the segmentation results given by these models are ensembled for the final segmentation of novel WM tracts. Our method was evaluated on public and in-house datasets. The experimental results show that our method improves the accuracy of one-shot segmentation of novel WM tracts.\",\n \"Title: Backstepping Fuzzy Adaptive Control Based on RBFNN for a Redundant Manipulator\\nYear: 2022\\n\\nAbstract: Redundant manipulator is a highly nonlinear and strongly coupled system. In practical application, dynamic parameters are difficult to determine due to uncertain loads and external disturbances. These factors will adversely affect the control performance of manipulator. In view of the above problems, this paper proposes a backstepping fuzzy adaptive control algorithm based on the Radial Basis Function Neural Network (RBFNN), which effectively eliminates the influence of the internal uncertainty and external interference on the control of the manipulator. Firstly, the algorithm adopts the backstepping method to design the controller framework. Then, the fuzzy system is used to fit the unknown system dynamics represented by nonlinear function to realize model-free control of the manipulator. The fuzzy constants are optimized by RBFNN to effectively eliminate the control errors caused by unknown parameters and disturbance. Finally, in order to realize RBFNN approximating the optimal fuzzy constant, an adaptive law is designed to obtain the weight value of RBFNN. The stability of the closed-loop system is proved by using Lyapunov stability theorem. Through simulation experiments, the algorithm proposed in this paper can effectively track the target joint angle when the dynamic parameters of the 7-DOF redundant manipulator are uncertain and subject to external torque interference. Compared with fuzzy adaptive control, the tracking error of the algorithm in this paper is smaller, and the performance is better.\",\n \"Title: Spatiotemporal Variation in Vegetation Growth Status and Its Response to Climate in the Three-River Headwaters Region, China\\nYear: 2022\\n\\nAbstract: The Three-River Headwaters Region (TRHR), located in the hinterland of the Qinghai-Tibet Plateau (QTP), is an important water-conservation and ecological-function reserve in China. Studies of the growth of vegetation in the TRHR and its response to climate under the background of global warming are of great relevance for ecological protection of the QTP. In this study, based on MOD13Q1 Enhanced Vegetation Index (EVI) data and ERA5-Land climate data, the ensemble empirical mode decomposition method, random forest algorithm, and Hurst exponent were used to detect the spatiotemporal dynamics and response to climate change in TRHR vegetation during 2000-2021. The results indicated the following. (1) Comparatively, the condition of vegetation growth was better in 2021, 2010, and 2018 and poorer in 2015, 2003, and 2008. The EVI gradually decreased from the southeast to the northwest, and the area of improved vegetation growth was larger than the area of degraded vegetation growth. (2) The area of zones with either monotonous greening or monotonous browning of vegetation was 30.30% and 6.30%, respectively, and the trend of reversed vegetation change occurred in 63.40% of the areas. The area of future degradation of vegetation in the TRHR was larger than the area of future improvement, and the risk of vegetation degradation was higher. (3) Precipitation and soil temperature are the main and secondary driving factors of vegetation change in the TRHR, respectively. Warming and humidification of the QTP climate play major roles in the improvement of vegetation growth in the TRHR.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":73,"string":"73"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":277,"string":"277"}}},{"rowIdx":278,"cells":{"question_id":{"kind":"string","value":"Fang Wu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Friendlee: a mobile application for your social life\" using the following items: 1. Friendlee\n2. Mobile social networking \n3. Intimate network\n4. Ambient awareness \n5. Non-intrusive manner"},"answer":{"kind":"string","value":"We have designed and implemented Friendlee, a mobile social networking application for close relationships. Friendlee analyzes the user's call and messaging activity to form an intimate network of the user's closest social contacts while providing ambient awareness of the user' social network in a compelling, yet non- intrusive manner."},"correct_answer":{"kind":"string","value":"We have designed and implemented Friendlee, a mobile social networking application for close relationships. Friendlee analyzes the user's call and messaging activity to form an intimate network of the user's closest social contacts while providing ambient awareness of the user' social network in a compelling, yet non- intrusive manner."},"documents":{"kind":"list like","value":["Title: Truth-Telling Reservations\nYear: 2008\n\nAbstract: We present a mechanism for reservations of bursty resources that is both truthful and robust. It consists of option contracts whose pricing structure induces users to reveal the true likelihoods that they will purchase a given resource. Users are also allowed to adjust their options as their likelihood changes. This scheme helps users save cost and the providers to plan ahead so as to reduce the risk of under-utilization and overbooking. The mechanism extracts revenue similar to that of a monopoly provider practicing temporal pricing discrimination with a user population whose preference distribution is known in advance.","Title: A variant of TNFR2-Fc fusion protein exhibits improved efficacy in treating experimental rheumatoid arthritis.\nYear: 2010\n\nAbstract: Etanercept, a TNF receptor 2-Fc fusion protein, is currently being used for the treatment of rheumatoid arthritis (RA). However, 25% to 38% of patients show no response which is suspected to be partially due to insufficient affinity of this protein to TNF alpha. By using computational protein design, we found that residue W89 and E92 of TNFR2 were critical for ligand binding. Among several mutants tested, W89Y/E92N displayed 1.49-fold higher neutralizing activity to TNFa, as compared to that of Etanercept. Surface plasmon resonance (SPR) based binding assay revealed that the equilibrium dissociation constant of W89Y/E92N to TNFa was 3.65-fold higher than that of Etanercept. In a rat model of collagen-induced arthritis (CIA), W89Y/E92N showed a significantly better ability than Etanercept in reducing paw swelling and improvement of arthritic joint histopathologically. These data demonstrate that W89Y/E92N is potentially a better candidate with improved efficacy in treating RA and other autoimmune diseases.","Title: Crowdsourcing, attention and productivity\nYear: 2008\n\nAbstract: We show through an analysis of a massive data set from YouTube that the productivity exhibited in crowdsourcing exhibits a strong positive dependence on attention, measured by the number of downloads. Conversely, a lack of attention leads to a decrease in the number of videos uploaded and the consequent drop in productivity, which in many cases asymptotes to no uploads whatsoever. Moreover, short-term contributors compare their performance to the average contributor芒聙聶s performance while long-term contributors compare it to their own media.","Title: Novelty And Collective Attention\nYear: 2007\n\nAbstract: The subject of collective attention is central to an information age where millions of people are inundated with daily messages. It is thus of interest to understand how attention to novel items propagates and eventually fades among large populations. We have analyzed the dynamics of collective attention among 1 million users of an interactive web site, digg.com, devoted to thousands of novel news stories. The observations can be described by a dynamical model characterized by a single novelty factor. Our measurements indicate that novelty within groups decays with a stretched-exponential law, suggesting the existence of a natural time scale over which attention fades.","Title: How Public Opinion Forms\nYear: 2008\n\nAbstract: No aspect of the massive participation in content creation that the web enables is more evident than in the countless number of opinions, news and product reviews that are constantly posted on the Internet. Given their importance we have analyzed their temporal evolution in a number of scenarios. We have found that while ignorance of previous views leads to a uniform sampling of the range of opinions among a community, exposure of previous opinions to potential reviewers induces a trend following process which leads to the expression of increasingly extreme views. Moreover, when the expression of an opinion is costly and previous views are known, a selection bias softens the extreme views, as people exhibit a tendency to speak out differently from previous opinions. These findings are not only robust but also suggest simple procedures to extract given types of opinions from the population at large.","Title: Popularity, novelty and attention\nYear: 2008\n\nAbstract: We analyze the role that popularity and novelty play in attracting the attention of users to dynamic websites. We do so by determining the performance of three different strategies that can be utilized to maximize attention. The first one prioritizes novelty while the second emphasizes popularity. A third strategy looks myopically into the future and prioritizes stories that are expected to generate the most clicks within the next few minutes. We show that the first two strategies should be selected on the basis of the rate of novelty decay, while the third strategy performs sub-optimally in most cases. We also demonstrate that the relative performance of the first two strategies as a function of the rate of novelty decay changes abruptly around a critical value, resembling a phase transition in the physical world.","Title: Texture classification of aerial image based on Bayesian networks with hidden nodes\nYear: 2007\n\nAbstract: Bayesian networks have emerged in recent years as a powerful data mining technique for handling uncertainty in Artificial Intelligence community. However, researchers in the classification area were not interested in Bayesian networks until the simplest kind of Bayesian networks, Naive Bayes Classifiers (NBC), came forth. From that time on, their success led to a recent furry of algorithms for learning Bayesian networks from raw data and triggered experts to explore more deeply into Bayesian networks as classifiers. Although many of learners produce good results on some benchmark data sets, there are still several problems: nodes ordering requirement, computational complexity, lack of publicly available learning tools. Therefore, this paper puts up a new method, Bayesian networks with hidden nodes, which adds some hidden nodes between correlated feature variables to Bayesian networks based on the maximal covariance criterion. Experimental results demonstrate that the proposed method is efficient and effective, and outperforms NBC and Bayesian Network Augmented Naive Bayes (BAN).","Title: Persistence and Success in the Attention Economy\nYear: 2009\n\nAbstract: A hallmark of the attention economy is the competition for the attention of\nothers. Thus people persistently upload content to social media sites, hoping\nfor the highly unlikely outcome of topping the charts and reaching a wide\naudience. And yet, an analysis of the production histories and success dynamics\nof 10 million videos from \\texttt{YouTube} revealed that the more frequently an\nindividual uploads content the less likely it is that it will reach a success\nthreshold. This paradoxical result is further compounded by the fact that the\naverage quality of submissions does increase with the number of uploads, with\nthe likelihood of success less than that of playing a lottery.","Title: Antecedents and Outcomes of E-Procurement Adoption: An Integrative Model\nYear: 2007\n\nAbstract: Organizations increasingly emphasize the use of information technology in the procurement process. An integrative model of e-procurement adoption that captures its antecedents, two types of e-procurement use, and their respective effects on relationship development and perceived efficiency gains are proposed and empirically tested using the data collected from senior managers in four technology-intensive industries. Our findings indicate that the use of coordination e-procurement applications has both direct and indirect effects on perceived efficiency gains, while transactional application use can directly lead to efficiency gains. In addition, the use of e-procurement applications is strongly influenced by organizational learning ability and normative pressures. The findings provide a new perspective for managers in their future implementation of e-procurement applications.","Title: Harvesting Collective Intelligence: Temporal Behavior in Yahoo Answers\nYear: 2010\n\nAbstract: When harvesting collective intelligence, a user wishes to maximize the\naccuracy and value of the acquired information without spending too much time\ncollecting it. We empirically study how people behave when facing these\nconflicting objectives using data from Yahoo Answers, a community driven\nquestion-and-answer site. We take two complementary approaches. We first study\nhow users behave when trying to maximize the amount of the acquired\ninformation, while minimizing the waiting time. We identify and quantify how\nquestion authors at Yahoo Answers trade off the number of answers they receive\nand the cost of waiting. We find that users are willing to wait more to obtain\nan additional answer when they have only received a small number of answers;\nthis implies decreasing marginal returns in the amount of collected\ninformation. We also estimate the user's utility function from the data. Our\nsecond approach focuses on how users assess the qualities of the individual\nanswers without explicitly considering the cost of waiting. We assume that\nusers make a sequence of decisions, deciding to wait for an additional answer\nas long as the quality of the current answer exceeds some threshold. Under this\nmodel, the probability distribution for the number of answers that a question\ngets is an inverse Gaussian, which is a Zipf-like distribution. We use the data\nto validate this conclusion.","Title: Route optimisation models and algorithms for hazardous materials transportation under different environments\nYear: 2013\n\nAbstract: This study focuses on how to determine the optimum transportation route for hazardous materials under the certain, fuzzy or stochastic environment. On the basis of analysing the transportation route selection problem of hazardous materials TRSP-HM, three objectives are presented and the multi-objective routing programming model MRPM for hazardous materials transportation HMT is put forward under the certain environment, and an improved label algorithm is proposed to solve the MRPM. After defining the maximum-chance optimum route and the α-optimum routes, the multi-objective routing chance-constrained programming model MRCPM and multi-objective routing dependent-chance programming model MRDPM for HMT under the fuzzy or stochastic environment are established respectively. Then, the integration intelligent algorithm is developed to solve the proposed models, which integrates the fuzzy simulation, neural networks, stochastic simulation and genetic algorithm. Finally, the proposed models and algorithms are successfully tested with the help of two real cases.","Title: The equilibrium generalized assignment problem and genetic algorithm.\nYear: 2012\n\nAbstract: The well-known generalized assignment problem (GAP) is to minimize the costs of assigning n jobs to m capacity constrained agents (or machines) such that each job is assigned to exactly one agent. This problem is known to be NP-hard and it is hard from a computational point of view as well. In this paper, follows from practical point of view in real systems, the GAP is extended to the equilibrium generalized assignment problem (EGAP) and the equilibrium constrained generalized assignment problem (ECGAP). A heuristic equilibrium strategy based genetic algorithm (GA) is designed for solving the proposed EGAP. Finally, to verify the computational efficiency of the designed GA, some numerical experiments are performed on some known benchmarks. The test results show that the designed GA is very valid for solving EGAP.","Title: Predicting defect priority based on neural networks\nYear: 2010\n\nAbstract: Existing defect management tools provide little information on how important/urgent for developers to fix defects reported. Manually prioritizing defects is time-consuming and inconsistent among different people. To improve the efficiency of troubleshooting, the paper proposes to employ neural network techniques to predict the priorities of defects, adopt evolutionary training process to solve error problems associated with new features, and reuse data sets from similar software systems to speed up the convergence of training. A framework is built up for the model evaluation, and a series of experiments on five different software products of an international healthcare company to demonstrate the feasibility and effectiveness.","Title: Ensuring trust in one time exchanges: solving the QoS problem\nYear: 2005\n\nAbstract: We describe a pricing structure for the provision of IT services that ensures trust without requiring repeated interactions between service providers and users. It does so by offering a pricing structure that elicits truthful reporting of QoS by providers while making them profitable. This mechanism also induces truth-telling on the part of users reserving the service.","Title: Human Speed-Accuracy Tradeoffs in Search\nYear: 2011\n\nAbstract: When foraging for information, users face a tradeoff between the accuracy and value of the acquired information and the time spent collecting it, a problem which also surfaces when seeking answers to a question posed to a large community. We empirically study how people behave when facing these conflicting objectives using data from Yahoo Answers, a community driven question-and-answer site. We first study how users behave when trying to maximize the amount of acquired information while minimizing the waiting time. We find that users are willing to wait longer for an additional answer if they have received a small number of answers. We then assume that users make a sequence of decisions, deciding to wait for an additional answer as long as the quality of the current answer exceeds some threshold. The resulting probability distribution for the number of answers that a question gets is an inverse Gaussian, a fact that is validated by our data.","Title: Public Discourse in the Web Does Not Exhibit Group Polarization\nYear: 2008\n\nAbstract: We performed a massive study of the dynamics of group delibera- tion among several websites containing millions of opinions on topics ranging from books to media. Contrary to the common phenomenon of group polarization observed offline, we measured a strong tendency towards moderate views in the course of time. This phenomenon possi- bly operates through a self-selection bias whereby previous comments and ratings elicit contrarian views that soften the previous opinions.","Title: Design And Implementation Of Ontology-Based Query Expansion For Information Retrieval\nYear: 2007\n\nAbstract: In Information Retrieval (IR), the user's input query conditions usually are not detailed enough, so the satisfactory query results can not be brought back. Query expansion of IR can help to solve this problem. However, the common query expansion in IR cannot get steady retrieval results. In this paper, we propose and implement query expansion method which combines domain ontology with the frequent of terms. Ontology is used to describe domain knowledge; logic reasoner and the frequency of terms arc used to choose fitting expansion words. By this way, higher recall and precise can be gotten as user' query results. Experimental results show that compared with the results of common query expansion, the method described in this paper can get statistically significant improvement in recall and precise combination.","Title: Opinion formation under costly expression\nYear: 2010\n\nAbstract: Opinions play an important role in trust building and the creation of consensus about issues and products and a number of studies have focused on the design, evaluation, and utilization of online opinion systems. However, little effort has been spent on the dynamic aspects of online opinion formation. In this article, we study the dynamics of online opinion expression by analyzing the temporal evolution of vey large sets of user views and determine that in the course of time, later opinions tend to show a big difference with earlier opinions, which moderates the average opinion to the less extreme. Online posters also tend to disagree with previous opinions when the cost of expression is high.","Title: Coastal erosion mapping through intergration of SAR and Landsat TM imagery\nYear: 2013\n\nAbstract: It is important to monitor long-term coastal erosion in countries such as Australia given the majority of our population live in coastal regions. However, ground-based surveys are labour-intensive and involve significant cost when large spatial areas need to monitored. This paper presents a complementary, cost-effective approach for mapping the eroded shoreline, through integrating Landsat multispectral (MS) imagery data and synthetic aperture radar (SAR) imagery data. This integration method overcomes the problem of data shortage associated with using a single data source. Moreover, it can extract the instant land-water interface at sub-pixel resolution. Because the extracted land-water boundaries are dynamic, a tidal model has to be applied to define the high water line. Wavelet transform and linear spectral unmixing are the two major algorithms used for extracting the land-water interface. Several inundated areas are identified at the selected study area along the coast of East Gippsland Basin, Victoria, Australia. Naturally occurring erosion is believed to be the major factor for these inundated areas. Theoretically the extracted shorelines for defining erosion can reach 1m - 2m resolution approximately.","Title: SSIS: Ontology-Based Analyzing and Reasoning of the Shanghai World Expo Knowledge\nYear: 2009\n\nAbstract: As a scheduled World Expo in the grand tradition of international fairs and expositions, Shanghai World Expo (SWE) has recently gained much attention for its highly sophisticated online vision called \"Online Expo Shanghai\". In this context, researchers are working to provide intelligent mechanisms to SWE. To support intelligent SWE managements and services, SWE modeling is an essential requirement to understand current (and future) large scale international exhibitions and to possibly drive more complex intelligent actions. In this paper, based on the knowledge representation technique of ontology modeling, we introduce the SWE ontology specifying of SWE's domain knowledge. It precisely describes the definition and basic hierarchical rules, properties, relations and instances of SWE; furthermore, a set of domain-specific axioms is derived from the specified classes and slots. The axiom repository is used for consistency checking and knowledge reasoning. It is viewed as the semantic base for SWE information services, and also the primary part of the SWE semantic inquire system (SSIS). We also briefly describe the top architecture of SSIS in which the SWE related knowledge inquiring services are contained and will be evaluated together with SSIS in a practical application project.","Title: Classifier assessment and feature selection for recognizing short coding sequences of human genes.\nYear: 2012\n\nAbstract: With the ever-increasing pace of genome sequencing, there is a great need for fast and accurate computational tools to automatically identify genes in these genomes. Although great progress has been made in the development of gene-finding algorithms during the past decades, there is still room for further improvement. In particular, the issue of recognizing short exons in eukaryotes is still not solved satisfactorily. This article is devoted to assessing various linear and kernel-based classification algorithms and selecting the best combination of Z-curve features for further improvement of the issue. Eight state-of-the-art linear and kernel-based supervised pattern recognition techniques were used to identify the short (21-192 bp) coding sequences of human genes. By measuring the prediction accuracy, the tradeoff between sensitivity and specificity and the time consumption, partial least squares (PLS) and kernel partial least squares (KPLS) algorithms were verified to be the most optimal linear and kernel-based classifiers, respectively. A surprising result was that, by making good use of the interpretability of the PLS and the Z-curve methods, 93 Z-curve features were proved to be the best selective combination. Using them, the average recognition accuracy was improved as high as 7.7% by means of KPLS when compared with what was obtained by the Fisher discriminant analysis using 189 Z-curve variables (Gao and Zhang, 2004). The used codes are freely available from the following approaches (implemented in MATLAB and supported on Linux and MS Windows): (1) SVM: http://www.support-vector-machines.org/SVM_soft.html. (2) GP: http://www.gaussianprocess.org. (3) KPLS and KFDA: Taylor, J.S., and Cristianini, N. 2004. Kernel Methods for Pattern Analysis. Cambridge University Press, Cambridge, UK. (4) PLS: Wise, B. M., and Gallagher, N. B. 2011. PLS-Toolbox for use with MATLAB: ver 1.5.2. Eigenvector Technologies, Manson, WA. Supplementary Material for this article is available at www.liebertonline.com/cmb.","Title: The economics of attention: maximizing user value in information-rich environments\nYear: 2008\n\nAbstract: We introduce an automatic configuration mechanism that generates the most relevant information to be presented to limited attention users of information-rich media. It also guarantees to maximize their total expected utility from the information they receive. A computationally efficient algorithm is used to assign an index value to each information item, which then determines whether or not a given item appears in the top list presented to users at a given time.","Title: A delay-optimized universal FPGA routing architecture\nYear: 2009\n\nAbstract: A universal FPGA routing Architecture is presented, which ensures that every module in the FPGA including CLBs and IOBs have a uniform interconnect architecture, and the load of interconnect lines is equally distributed. So, this architecture is highly repeatable and the signal delay is predictable and regular. Furthermore, the realization of the Programmable Interconnect Point (PIP) and the BUFFER driver is also optimized to benefit the signal delay up to 5%. The test results of the example chip show the reasonableness of these ideas.","Title: Networked Control With Reset Quantized State Based on Bernoulli Processing\nYear: 2014\n\nAbstract: This paper considers the problem of reset quantized state control for a class of continuous-time linear system. The logarithmic quantization scheme is employed in the network-based information communication, and a reset state observer is introduced which is based on the standard one to suppress sensor quantization effects. A Bernoulli processing approach is presented to reset the value of the observer with a random way in continuous-time domain. The resulting reset error system is a class of hybrid system which contains both discrete-time and continuous-time stochastic error dynamics. By the stochastic Lyapunov method, it is derived that the error system under the proposed reset technique is asymptotically stable in the sense of each discrete “reset” time instant, and mean-square stable in the continuous-time domain except those “reset” time instants. The observer and controller gains of the closed-loop systems are obtained via solving linear matrix inequalities. Finally, a numerical example is provided to illustrate the effectiveness of the proposed approach.","Title: Fault Detection and Diagnosis in Process Data Using Support Vector Machines.\nYear: 2014\n\nAbstract: For the complex industrial process, it has become increasingly challenging to effectively diagnose complicated faults. In this paper, a combined measure of the original Support Vector Machine (SVM) and Principal Component Analysis (PCA) is provided to carry out the fault classification, and compare its result with what is based on SVM-RFE (Recursive Feature Elimination) method. RFE is used for feature extraction, and PCA is utilized to project the original data onto a lower dimensional space. PCA T-2, SPE statistics, and original SVM are proposed to detect the faults. Some common faults of the Tennessee Eastman Process (TEP) are analyzed in terms of the practical system and reflections of the dataset. PCA-SVM and SVM-RFE can effectively detect and diagnose these common faults. In RFE algorithm, all variables are decreasingly ordered according to their contributions. The classification accuracy rate is improved by choosing a reasonable number of features.","Title: Detection Method for Credibility Defect of Simulation Based on Sobol' Method and Orthogonal Design.\nYear: 2013\n\nAbstract: Against the defect detection problem of simulation credibility, a method based on Sobolspi0215e method and orthogonal design is proposed. Firstly, taking acceptable range of simulation credibility as measurement standard, then credible indexes and incredible indexes of simulation system are determined. Secondly, experiment scheme is arranged according to an extended table transformed from orthogonal table, and incredible indexspi0215es defect rank is judged by experimental result analysis combining with membership function of defect rank. Thirdly, Latin Hypercube sampling is taken from relevant indexes of incredible index, and then sensitivity coefficients of relevant indexes are calculated using Sobolspi0215e method. Finally an example is given to validate the effectiveness of the proposed method. © Springer-Verlag Berlin Heidelberg 2013.","Title: Feedback Loops of Attention in Peer Production\nYear: 2009\n\nAbstract: A significant percentage of online content is now published and consumed via the mechanism of crowdsourcing. While any user can contribute to these forums, a disproportionately large percentage of the content is submitted by very activeand devoted users, whose continuing participation is key to thesites’ success. As we show, people’s propensity to keep participating increases the more they contribute, suggesting motivating factors which increase over time. This paper demonstrates that submitters who stop receiving attention tend to stop contributing, while prolific contributors attract an ever increasing number offollowers and their attention in a feedback loop. We demonstrate that this mechanism leads to the observed power law in the number of contributions per user and support our assertions by an analysis of hundreds of millions of contributions to top content sharing websites Digg.com and Youtube.com.","Title: A novel SPDF ensemble classifier for cancer classification\nYear: 2013\n\nAbstract: To gain more accurate and reliable cancer classification results through DNA microarray analysis, a novel ensemble classifier SPDF (Subspace Partial least square based Decision Forest) is developed. The original data are split into subspaces by column. For each subspace, partial least square (PLS) is applied to extract orthogonal latent variables (LVs). In conjunction with the Minimal Redundancy and Maximal Relevance (MRMR) as the gene-selection preprocessing method, the adverse effect of the too high dimensional variables with too small samples could be overcome successfully. Then, all available LVs are aggregated as the new training data where the Decision Forest is trained for classification. Therefore relying on the feature extraction power of PLS and the orthogonality of LVs, the multi-colinearity and high noise inherent in microarray data could be eliminated effectively. Moreover, the Decision Forest could enhance the data variety and further lighten the dependence of the classification results to the given data. The applications to two microarray datasets show that compared with Rotation Forest, Bagging and Boosting, the new SPDF method yields consistently accurate and robust predictive performance, with the maximal improvement reaching 7.26% in terms of classification accuracy on the Colon cancer classification.","Title: Study on urban three-lane mixed traffic flow with buses based on the Nagel-Schreckenberg model\nYear: 2013\n\nAbstract: On the basis of Nagel-Schreckenberg NaSch traffic flow model, a new Three-lane Fuzzy Cellular Automaton TFCA model for mixed traffic with buses is established. In our study, the fuzzy control rules are used to determine the random parameters which are capable of describing the mixed traffic flow, especially the braking rate, lane change rules, overtaking and random slow mechanisms of buses are reset just for analysis of psychological factors of bus drivers. Finally the developed TFCA model has been validated by using computer simulation. The results show that the model could be used to reveal the essence of urban three-lane mixed traffic flow characteristics.","Title: A Novel Spatial Clustering with Obstacles Constraints Based on Genetic Algorithms and K-Medoids\nYear: 2006\n\nAbstract: Spatial clustering is an important research topic in Spatial Data Mining (SDM). Many methods have been proposed in the literature, but few of them have taken into account constraints that may be present in the data or constraints on the clustering. These constraints have significant influence on the results of the clustering process of large spatial data. In this paper, we discuss the problem of spatial clustering with obstacles constraints and propose a novel spatial clustering method based on Genetic Algorithms (GAs) and KMedoids, called GKSCOC, which aims to cluster spatial data with obstacles constraints. It can not only give attention to higher local constringency speed and stronger global optimum search, but also get down to the obstacles constraints and practicalities of spatial clustering. The results on real datasets show that it is better than standard GAs and K-Medoids.","Title: Bootstrapping the Long Tail in Peer to Peer Systems\nYear: 2005\n\nAbstract: Abstract We describe an e‐cient incentive mechanism for P2P systems that generates a wide diversity of content ofierings while responding adaptively to customer demand.,Files are served and paid for through a parimutuel market similar to that used for betting in horse races and in lotteries. An analysis of the performance of such a system shows that there exists an equilibrium with a long tail in the distribution of content ofierings, which guarantees the real time provision of any content regardless of its popularity.","Title: A simulated annealing for multi-criteria optimization problem: DBMOSA.\nYear: 2014\n\nAbstract: This paper investigates a simulated annealing (SA) for multi-criteria optimization problem (MOP) which incorporates the concept of archive in order to provide a set of tradeoff solutions for the problem under consideration. To determine the acceptance probability of a new solution, an evaluation measure of multi-criteria objective function is proposed which takes into account the dominant relation between the new and current solutions, as well as those in the archive. In addition, a mutation operator is proposed in which the constraints of MOP can be partially handled. To efficiently apply the proposed SA into constrained MOP (CMOP), an equivalent relaxation approach is proposed by which the CMOP, say primal problem, can be equivalently transformed into an unconstrained MOP, say relaxation problem. Based on such a constraints handling technique (CHT), it is theoretically proved that the primal problem and the relaxation problem have the same efficient set (ES) and the proposed CHT is then further extended into two existing multi-criteria optimization (MO) evolutionary algorithms (EA) (MOEA), say AMOSA and NSGA-II, respectively. Two performance metrics are proposed to evaluate the performance of the MOEAs. Finally, a comprehensive comparative study among AMOSA, NSGA-II and the proposed SA is performed on some popular benchmarks for MOP algorithms to show the effectiveness of the proposed SA and CHT. The comparative study shows that the overall performance of the proposed SA is generally superior to both of the AMOSA and NSGA-II, particularly, for the MOPs with three objectives the performance of the former is far better than the latter, and the proposed CHT can be very conveniently extended into any of the existing EAs for MOP such that they can be applied to solve the CMOPs.","Title: Proportional response dynamics leads to market equilibrium\nYear: 2007\n\nAbstract: One of the main reasons of the recent success of peer to peer (P2P)file sharing systems such as BitTorrent is their built-in tit-for-tat mechanism. In this paper, we model the bandwidth allocation in a P2P system as an exchange economy and study a tit-for-tat dynamics, namely the proportional response dynamics, in this economy. In aproportional response dynamics each player distributes its good to its neighbors proportional to the utility it received from them in thelast period. We show that this dynamics not only converges but converges to a market equilibrium, a standard economic characterization of efficient exchanges in a competitive market. In addition, for some classes of utility functions we consider, it converges much faster than the classical tat process and any existingalgorithms for computing market equilibria. As a part of our proof we study the double normalization of a matrix, an operation that linearly scales the rows of a matrix sothat each row sums to a prescribed positive number, followed by a similar scaling of the columns. We show that the iterative double normalization process of any non-negative matrix always converges. This complements the previous studies in matrix scaling that has focused on the convergence condition of the process when the row and column normalizations are considered as separate steps.","Title: Multi-objective fuzzy optimisation method for emergency evacuation based on hybrid intelligence algorithm under fuzzy environment\nYear: 2013\n\nAbstract: After a sudden public event, how to optimise emergency evacuation routings and enhance the response capability of emergency system is an important issue for emergency management agency. In this paper, we choose the optimal evacuation routing under fuzzy environment to make sure the injured reach the destination safely and quickly. Chance-constrained programming model of emergency evacuation routings and chance-dependent constraint programming models are setup respectively and a hybrid intelligence algorithm is designed to solve the model. The algorithm, which combines simulation technique and the genetic algorithm, produces chromosomes according to priority-based coding mode, uses simulation technique to calculate target values of chromosomes, produces a new group by using improved roulette wheel method to select chromosomes, crosses by adopting the partially matched crossover method, and uses reciprocal exchange mutation method to mutate. Finally, an example is presented to validate the feasibility of this model and the algorithm. The research result can help emergency decision-makers to find an optimal route after a sudden public event and reduce the casualties caused by transportation delays.","Title: Latent Ringlike Road Traffic Control System Based On Compound Mechanism Particle Swarm Optimisation Algorithm\nYear: 2013\n\nAbstract: Urban traffic congestion is one of the most severe problems of everyday life in many cities. In an effort to deal with this problem, traffic control system technologies have concentrated in recent years on dealing with urban congestion. In the paper, a compound mechanism particle swarm optimisation (CMPSO) algorithm has been proposed, and the algorithm has been effectively used in dealing with the optimisation of city latent ringlike road traffic control system. In the algorithm, the tabu search algorithm and the particle swarm algorithm are combined effectively, and the tabu can offset the local optimums and avoid searching one solution repeatedly. Simulations show the CMPSO algorithm cannot only avoid premature convergence effectively, but also has powerful optimisation ability and higher precision. It makes the rate of delay and numbers of stopping reduce obviously.","Title: Quantized H output feedback control for linear discrete-time systems\nYear: 2013\n\nAbstract: This paper investigates the robust H∞ dynamic output feedback control problem for networked control systems (NCSs) with quantized measurements. The measurement losses of the communicated information are considered in an unreliable communication channel. The robust H∞ dynamic output feedback controllers are designed to handle the measurement losses and mitigate the quantization effects such that the resultant closed-loop NCS is mean-square stochastically stable with a prescribed H∞ disturbance attenuation performance. The controller existence conditions can be derived in terms of linear matrix inequalities (LMIs). Finally, an example is provided to illustrate the effectiveness of the proposed approach.","Title: Steel plates fault diagnosis on the basis of support vector machines.\nYear: 2015\n\nAbstract: Fault diagnosis is always a big concern in industry production. As industrial technology has developed a lot, new fault diagnosis methods are needed to distinguish faults with only fine distinctions. The higher quality a production is required to have, the better fault diagnosis method the factories should apply. A fault diagnosis method based on modified Support Vector Machines (SVMs) is shown in this paper. With this method, dimension of samples is effectively reduced by recursive feature elimination (RFE) algorithm, and computing time is saved at the same time. Besides, classification accuracy is improved by parameter optimizing and sample size balancing strategy. A faults dataset of steel plates is taken as a practical case. And SVMs that are modified by different algorithms are utilized to complete fault diagnosis. This combined measure shows its superiority in sorting common faults of steel plates over original SVMs. Some essential procedures in model developing, such as normalization and cross validation, are also referred to.","Title: Step-wise support vector machines for classification of overlapping samples\nYear: 2015\n\nAbstract: mong machine learning algorithms, Support Vector Machine (SVM) is outstanding for its high efficiency and good generalization ability. This paper mainly concerns the classification performance of SVMs for multiple classes and auxiliary algorithms combined with SVMs. These auxiliary algorithms include Recursive Feature Elimination (RFE) algorithm, parameters optimizing methods and Two-Step Classification strategy. Results are given under data-based framework that classification ability and operation efficiency of SVMs are both improved when dimension is reduced; and Two-Step Classification SVM (TSC-SVM) works well under circumstances that samples overlap with each other seriously. In TSC-SVM, differences between adjacent samples are denoised by wavelet transform and magnified by a proper weighting function, after samples are sorted into correct groups in the first step. Discussions and comparisons are based on abalone dataset. According to the simulations, it is believed that step-wise SVMs have superior classification ability.","Title: A person-environment-object model for data acquisition method of microscopic behavior\nYear: 2014\n\nAbstract: Behavior research is limited by the accessibility of the microscopic behavior data. In this study, a PEO (Person-Environment-Object) model is proposed to decompose the diverse microscopic behavior in real world into simple and measurable variables such as position, status, time, and etc., which serves as a foundation for the behavioral data collection. According to the PEO model, then the framework of acquisition program for microscopic behavior data is established based on wireless sensor technology, in order to provide high spatial and temporal resolution behavioral data for deep behavior research and its applications.","Title: Orientation measurement based on magnetic inductance by the extended distributed multi-pole model.\nYear: 2014\n\nAbstract: This paper presents a novel method to calculate magnetic inductance with a fast-computing magnetic field model referred to as the extended distributed multi-pole (eDMP) model. The concept of mutual inductance has been widely applied for position/orientation tracking systems and applications, yet it is still challenging due to the high demands in robust modeling and efficient computation in real-time applications. Recently, numerical methods have been utilized in design and analysis of magnetic fields, but this often requires heavy computation and its accuracy relies on geometric modeling and meshing that limit its usage. On the other hand, an analytical method provides simple and fast-computing solutions but is also flawed due to its difficulties in handling realistic and complex geometries such as complicated designs and boundary conditions, etc. In this paper, the extended distributed multi-pole model (eDMP) is developed to characterize a time-varying magnetic field based on an existing DMP model analyzing static magnetic fields. The method has been further exploited to compute the mutual inductance between coils at arbitrary locations and orientations. Simulation and experimental results of various configurations of the coils are presented. Comparison with the previously published data shows not only good performance in accuracy, but also effectiveness in computation.","Title: Sequential systems of linear equations algorithm for nonlinear optimization problems--general constrained problems\nYear: 2004\n\nAbstract: In Ref. [J. Comput. Math. 20 (3) (2002) 301], a new superlinearly convergent algorithm of sequential systems of linear equations for nonlinear optimization problems with inequality constraints was proposed. Since the new algorithm only needs to solve four systems of linear equations having a same coefficient matrix per iteration, the computation amount of the algorithm is much less than that of the existing sequential quadratic programming algorithms per iteration. Under some mild assumptions, the new algorithm is globally convergent and its rate of convergence is one-step superlinearly. In this paper, it is shown that the new algorithm also can be used to deal with nonlinear optimization problems having nonlinearly equality and inequality constraints, by solving an auxiliary problem. Some numerical results are reported.","Title: Support vector regression based approach for key index forecasting with applications\nYear: 2015\n\nAbstract: With the rapid development in science and technology, data acquisition, storage and mining technology are widely applied to various fields. All aspects of people's lives are recorded as data. Through the analyzing and arranging of data, people can get a lot of valuable information. In this paper, support vector machine (SVM), least squares support vector machine (LSSVM) and partial least squares (PLS) are respectively used in the field of economic research. Real-time monitoring and forecasting for stock index is vital to the market. The changing trend and index of stocks are predicted according to the analysis to the history data of the stock. By combining particle swarm algorithm (PSO) algorithm and LSSVM algorithm, the parameters in the LSSVM model can be optimized. These algorithms are compared on the basis of their forecasting results.","Title: A New Simplification Approach Based on the Oblique-Dividing-Curve Method for Contour Lines.\nYear: 2016\n\nAbstract: As one of the key operators of automated map generalization, algorithms for the line simplification have been widely researched in the past decades. Although many of the currently available algorithms have revealed satisfactory simplification performances with certain data types and selected test areas, it still remains a challenging task to solve the problems of (a) how to properly divide a cartographic line when it is too long to be dealt with directly; and (b) how to make adaptable parameterizations for various geo-data in different areas. In order to solve these two problems, a new line-simplification approach based on the Oblique-Dividing-Curve (ODC) method has been proposed in this paper. In this proposed model, one cartographic line is divided into a series of monotonic curves by the ODC method. Then, the curves are categorized into different groups according to their shapes, sizes and other geometric characteristics. The curves in different groups will trigger different strategies as well as the associated criteria for line simplification. Whenever a curve is simplified, the whole simplified cartographic line will be re-divided and the simplification process restarts again, i.e., the proposed simplification approach is iteratively operated until the final simplification result is achieved. Experiment evidence demonstrates that the proposed approach is able to handle the holistic bend-trend of the whole cartographic line during the simplification process and thereby provides considerably improved simplification performance with respect to maintaining the essential shape/salient characteristics and keeping the topological consistency. Moreover, the produced simplification results are not sensitive to the parameterizations of the proposed approach.","Title: A Spatial Conditioned Latin Hypercube Sampling Method for Mapping Using Ancillary Data.\nYear: 2016\n\nAbstract: For obtaining maps of good precision by the spatial inference method, the distribution of sampling sites in geographical and feature space is very important. For a regional variable with trends, the predicting error comes from trend estimation, variogram estimation and spatial interpolation. Based on the cLHS (conditioned Latin hypercube Sampling) method, a sampling method called scLHS (spatial cLHS) considering all these three aspects with the help of ancillary data is proposed in this article. Its advantage lies in simultaneously improving trend estimation, variogram estimation and spatial interpolation. MODIS data and simulated data were used as sampling fields to draw sample sets using scLHS, cLHS, cLHS with x and y coordinates as covariates, simple random and spatial even sampling methods, and the distribution and prediction errors of sample sets from different methods were evaluated. The results showed that scLHS performed well in balancing spreading in geographic and feature space, and can generate points pairs with small distances, and the sample sets drawn by scLHS produced smaller mapping error, especially when there were trends in the target variable.","Title: A Compact Magnetic Field-Based Obstacle Detection and Avoidance System for Miniature Spherical Robots.\nYear: 2017\n\nAbstract: Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical robots, yet very limited studies have been conducted regarding the obstacle avoidance capability of spherical robots. Most of the existing spherical robots rely on the \"hit and run\" technique, which has been argued to be a reasonable strategy because spherical robots have an inherent ability to recover from collisions. Without protruding components, they will not become stuck and can simply roll back after running into bstacles. However, for small scale spherical robots that contain sensitive surveillance sensors and cannot afford to utilize heavy protective shells, the absence of obstacle avoidance solutions would leave the robot at the mercy of potentially dangerous obstacles. In this paper, a compact magnetic field-based obstacle detection and avoidance system has been developed for miniature spherical robots. It utilizes a passive magnetic field so that the system is both compact and power efficient. The proposed system can detect not only the presence, but also the approaching direction of a ferromagnetic obstacle, therefore, an intelligent avoidance behavior can be generated by adapting the trajectory tracking method with the detection information. Design optimization is conducted to enhance the obstacle detection performance and detailed avoidance strategies are devised. Experimental results are also presented for validation purposes.","Title: Quality Assessment Method for Linear Feature Simplification Based on Multi-Scale Spatial Uncertainty.\nYear: 2017\n\nAbstract: This study discusses a method for quantitative quality assessment for the simplification of linear features. Considering the multi-scale nature of linear features, this paper combines the improved Douglas-Peucker method without threshold and the multiway tree model to construct a weighted hierarchical linear feature representation model called the Douglas-Peucker Multiway Tree (DMC-tree). Subsequently, the uncertainty computation is conducted from the root of the DMC-Tree top-down level by level to obtain the quality indexes. Then, the quality index of the whole linear feature is obtained by combining the indexes of every layer together with their weights. The results of the presented method are compared with those of the length ratio method and the Hausdorff distance method. The results show the advantages of the presented method over the others, including (1) its sensitivity to feature points of multiple scales, (2) the quantitative characteristics of the indexes, and (3) the finer granularity in assessment.","Title: Does research on digital public relations indicate a paradigm shift? An analysis and critique of recent trends.\nYear: 2017\n\nAbstract: •Imbalanced attention to social media from academia and practitioners.•Digital PR studies are gradually shifting from description to theorization.•Methodological diversification needs to continue for robust digital PR research.•Organizational perspective dominates, with increasing attention to NPOs.","Title: A Progressive Method of Simplifying Polylines with Multi-bends Simplification Templates.\nYear: 2017\n\nAbstract: Polyline simplification is one of the most important and classic researches in multi-scale expression of cartography and GIS. Polyline simplification methods based on bend units get widespread attention recently. Having analyzed the bends composing characteristics and the manual simplification process of polylines, it is resonable to find that not all of invisible bend units are deleted directly. A new progressive simplification method based on multi-bends groups is proposed. Firstly, based on the threshold of the simplified scale, polylines are divided into multi-bends groups. Secondly, in order to avoid over-simplification, some reasonable bends deletion options which called multi-bends templates are proposed. However multi-bends templates is not steady and always related to the quantity of multi-bends uniquely. Considering of the minimal errors derived form polyline simplification, the best multi-bends template that result in the least displacement is selected to simplify muli-bends groups. Thirdly, polylines do not stop repeating the above two steps until all bend units of simplified polylines can be detected in the simplified scale. Experiments with real road-net data were implemented, and comparison with other algorithms is discussed. Results show advantages including: (i) The proposed algorithm is a progressive simplification process which is conform to human cognition. (ii) The proposed algorithm can preserve the main shape of the polyline with deleting invisible bend units enough. (iii) The proposed algorithm avoid unnecessary displacement by deleting bend units as little possible.","Title: Co-design of event generator and state estimator for complex network systems with quantization.\nYear: 2016\n\nAbstract: This paper studies the problem of event-triggered state estimation for complex network systems with quantization. The event-triggered communication scheme and quantization are employed to reduce the burden of network transmission. By utilizing Lyapunov stability theory and linear matrix inequality techniques, sufficient conditions are established which can ensure the augmented estimation error system to be asymptotically stable. Furthermore, the explicit expressions of the desired state estimators are derived in terms of linear matrix inequalities. Finally, an example is provided to illustrate the usefulness of the proposed method.","Title: Shape Similarity Assessment Method for Coastline Generalization.\nYear: 2018\n\nAbstract: Although shape similarity is one fundamental element in coastline generalization quality, its related research is still inadequate. Consistent with the hierarchical pattern of shape recognition, the Dual-side Bend Forest Shape Representation Model is presented by reorganizing the coastline into bilateral bend forests, which are made of continuous root-bends based on Constrained Delaunay Triangulation and Convex Hull. Subsequently, the shape contribution ratio of each level in the model is expressed by its area distribution in the model. Then, the shape similarity assessment is conducted on the model in a top-down layer by layer pattern. Contrast experiments are conducted among the presented method and the Length Ratio, Hausdorff Distance and Turning Function, showing the improvements of the presented method over the others, including (1) the hierarchical shape representation model can distinguish shape features of different layers on dual-side effectively, which is consistent with shape recognition, (2) its usability and stability among coastlines and scales, and (3) it is sensitive to changes in main shape features caused by coastline generalization.","Title: Evaluation and Application of Fuzzy Factors in Road Network Selection\nYear: 2018\n\nAbstract: Road's weights are vital in road network selection, as they can represent the relative importance of the roads among the road network. In the existing algorithms, three types of characteristics of roads, i.e. geometrical, topological and distribution characteristics, have been taken into account as the measure of roads' weights. But there are other characteristics such as traffic flow, economical value or culture value may affect the roads' importance in road networks, which are called fuzzy factors in the new algorithm because they are usually difficulty to measure by a certain value. To fill this gap, the paper propose a new algorithm take into account these fuzzy factors during road network selection. The basic idea is as follows: 1) fuzzy factors which should be taken into consideration in the process of road networks selection are proposed, and a comprehensive evaluation is made on these fuzzy factors; 2) the evaluated result is introduced into the road network selection. Experiment shows that the new algorithm taking into account the fuzzy factors not only inherits the advantages of the existing algorithm, but also considers the factors which are ignored in the existing algorithms, the selection results are more reasonable and in line with people's actual needs.","Title: A Mobile Application for Dog Breed Detection and Recognition Based on Deep Learning\nYear: 2018\n\nAbstract: Deep learning provides the ability to train algorithms (models) that can tackle the problems of data classification and prediction based on deriving (learning) knowledge from raw data. Convolutional Neural Networks (CNNs) provides one commonly used approach for image classification and detection. In this work we describe a CNN-based method for detecting dogs in potentially complex images and subsequently consider the identification of the type/breed of dogs. The results achieve nearly 85% accuracy for breed classification for a set of 50 classes of dogs and 64% accuracy for 120 other less common dog types. An iOS application and associated big data processing infrastructure utilizing a variety of GPUs was used to support the image classification algorithms.","Title: An Algorithm based on the Weighted Network Voronoi Diagram for Point Cluster Simplification.\nYear: 2019\n\nAbstract: Points on maps that stand for geographic objects such as settlements are generally connected by road networks. However, in the existing algorithms for point cluster simplification, points are usually viewed as discrete objects or their distances are considered in Euclidean spaces, and therefore the point cluster generalization results obtained by these algorithms are sometimes unreasonable. To take roads into consideration so that point clusters can be simplified in appropriate ways, the network Voronoi diagram is used and a new algorithm is proposed in this paper. First, the weighted network Voronoi diagram is constructed taking into account the weights of the points and the properties of the related road segments. Second, the network Voronoi polygons are generated and two factors (i.e., the area of the network Voronoi polygon and the total length of the dilated road segments in the polygon) are considered as the basis for point simplification. Last, a Cartesian coordinate system is built based on the two factors and the point clusters are simplified by means of the \"concentric quadrants\". Our experiments show that the algorithm can effectively and correctly transmit types of information in the process of point cluster simplification, and the results are more reasonable than that generated by the ordinary Voronoi-based algorithm and the weighted Voronoi-based algorithm.","Title: Collision-aware Task Assignment for Multi-Robot Systems\nYear: 2019\n\nAbstract: We propose a novel formulation of the collision-aware task assignment (CATA) problem and a decentralized auction-based algorithm to solve the problem with optimality bound. Using a collision cone, we predict potential collisions and introduce a binary decision variable into the local reward function for task bidding. We further improve CATA by implementing a receding collision horizon to address the stopping robot scenario, i.e. when robots are confined to their task location and become static obstacles to other moving robots. The auction-based algorithm encourages the robots to bid for tasks with collision mitigation considerations. We validate the improved task assignment solution with both simulation and experimental results, which show significant reduction of overlapping paths as well as deadlocks.","Title: Extracting Main Center Pattern from Road Networks Using Density-Based Clustering with Fuzzy Neighborhood\nYear: 2019\n\nAbstract: The spatial pattern is a kind of typical structural knowledge that reflects the distribution characteristics of object groups. As an important semantic pattern of road networks, the city center is significant to urban analysis, cartographic generalization and spatial data matching. Previous studies mainly focus on the topological centrality calculation of road network graphs, and pay less attention to the delineation of main centers. Therefore, this study proposes an automatic recognition method of main center pattern in road networks. We firstly extract the main clusters from road nodes by improving the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) with fuzzy set theory. Moreover, the center area is generated with road meshes according to the area ratio with the covering discs of the main clusters. This proposed algorithm is applied to the road networks of a monocentric city and polycentric city respectively. The results show that our method is effective for identifying the main center pattern in the road networks. Furthermore, the contrast experiments demonstrate our method's higher accuracy.","Title: Pattern Recognition Of Complex Distributed Ditches\nYear: 2021\n\nAbstract: The ditch pattern reflects the distribution characteristics of an agricultural drainage system and needs to be detected to enrich the data source before map generalization. Due to several breaks, the connectivity of the ditches is destroyed between ditches and rivers in map representation, making its structure complex. Previous studies have primarily focused on extracting parallel ditches, paying less attention to complex ditches with breaks. The pattern recognition of ditches does not merely involve the extraction of parallel relation. It involves the extraction of different level relations, which is a great challenge. Therefore, this study proposes a novel model to describe the complex structure of ditches. Our work consisted of the following three main contributions: (1) the collinear relation was defined to detect the groups of ditch segments separated by breaks, (2) the detection method of parallel relation was improved throughout the multi-parameter combined constraints, and (3) the main-tributary relation was proposed to build a connection between parallel groups and rivers. The experimental results showed that the proposed method was solved effectively in complex ditch pattern recognition.","Title: Finite-time passivity and synchronization of coupled complex-valued memristive neural networks\nYear: 2021\n\nAbstract: The finite-time passivity and finite-time synchronization issues for two categories of coupled complex-valued memristive neural networks with and without time-varying delay are discussed. First, by selecting a suitable control scheme and exploiting some inequality techniques, several finite-time passivity conditions are proposed for coupled complex-valued memristive neural networks without time-varying delay. Based on the obtained finite-time passivity condition, a criterion for finite-time synchronization for the considered network is also established. Furthermore, for coupled complex-valued memristive neural networks with time-varying delay, some criteria are established to guarantee that the considered network is finite-time passive and finite-time synchronized by developing an appropriate controller and deploying the Lyapunov functional method. Finally, two numerical examples with simulations substantiate the correctness and validity of the results.","Title: Finite-time synchronization and H∞ synchronization of coupled complex-valued memristive neural networks with and without parameter uncertainty\nYear: 2022\n\nAbstract: In this paper, finite-time synchronization and H∞ synchronization of coupled complex-valued memristive neural networks (CCVMNNs) with or without parameter uncertainty are analyzed. First, a finite-time synchronization (FTS) condition is presented for CCVMNNs by means of deploying Lyapunov stability theory and developing suitable controllers. Then, we utilize the similar method to derive a criterion of robust finite-time synchronization (RFTS) for the proposed CCVMNNs with uncertain parameter. Furthermore, we establish some criteria for the sake of ensuring that the considered network can reach finite-time H∞ synchronization and robust finite-time H∞ synchronization. At last, two numerical examples with simulations demonstrate the validity of the acquired results.","Title: Direct Sparse Odometry With Planes\nYear: 2022\n\nAbstract: We propose a novel formulation to use plane primitives in the direct sparse odometry formulation. Unlike existing SLAM works that introduce geometric error terms to account for planes, our method keeps the full error as purely photometric. The proposed system exploits the segmentation masks and plane parameters from a deep neural network and jointly optimizes the camera poses, 3D points, and 3D planes. The tightly-coupled formulation improves the pose estimation by fusing information on high-level geometric primitives and also refines the outputs of the plane detection network during optimization.","Title: Complex Fluctuation of Power Price in Dual-Channel and Multienergy Supply Chain Based on Sticky Expectation\nYear: 2021\n\nAbstract: According to the current power supply focused reform in China, a dual-channel and multienergy supply chain model is constructed. The supply chain has a new energy enterprise, a traditional energy enterprise, and the State Grid that is the retailer. New energy company and traditional energy company sell electricity to the State Grid at wholesale prices, and at the same time they enter the market to retail power products. Multiequilibriums and their practical significance are discussed. The complex dynamic is investigated using a bifurcation diagram, Lyapunov exponent, parameter basin, and fractal dimension. In this multilayer supply chain network, the price adjustment of the State Grid will make the entire supply chain face greater volatility risks, and dual-channel suppliers, that is, new energy and traditional energy companies are also involved in this volatility. Further, considering the sticky information, the sticky expectation of electricity price is built for studying the lagging electricity price. The dynamic characteristics of the sticky model are investigated, and new phenomena are discovered: 3-orbit bifurcation and mutation appear with fractals. This means that prices continue to swing and oscillate on three tracks. Through comparison of the fractal dimension, an important conclusion is discovered: the purpose of sticky expectations for electricity prices is to stabilize price fluctuations, but sticky expectations make the market more complicated. The article provides a strategic reference for exploring the power market in China.","Title: Sliding Bifurcation in Planar Piecewise Smooth Systems with Two Zones Separated by an Ellipse\nYear: 2021\n\nAbstract: The objective of this paper is to study the sliding bifurcation in a planar piecewise smooth system with an elliptic switching curve. Some new phenomena are observed, such as a crossing limit cycle containing four intersections with the switching curve, sliding cycles having four sliding segments, and sliding cycles consisting of the entire switching curve. Firstly, we investigate the bifurcation of sliding cycle from a sliding heteroclinic connection to two cusps and show the appearance of one sliding cycle with two folds. To plot the bifurcation diagram, a planar piecewise linear system with two zones separated by an ellipse are considered. Moreover, we study in more detail the unfolding of a sliding cycle connecting four cusps by exhibiting its complete bifurcation diagram. More precisely, we explore the necessary and sufficient conditions for the existence of limit cycles and derive the concrete bifurcation curves. Additionally, a simple piecewise smooth system with nonlinear subsystems is studied, which shows the possibility of the existence of two nested limit cycles. Finally, numerical simulations are given to confirm the theoretical analysis.","Title: Noise Error Pattern Generation Based on Successive Addition-Subtraction for GRAND-MO\nYear: 2022\n\nAbstract: Guessing random additive noise decoding (GRAND) is a capacity-approaching universal algorithm. The GRAND Markov order (GRAND-MO) variant is effective to correct burst errors in a Markov chain modeled memory channel, and the core of GRAND-MO is to generate putative noise error patterns in MO effectively. For purpose of a uniform noise error pattern generation scheme of GRAND-MO, this letter propose...","Title: Digital twin-enabled dynamic scheduling with preventive maintenance using a double-layer Q-learning algorithm\nYear: 2022\n\nAbstract: Dynamic scheduling methods are essential and critical to manufacturing systems because of uncertain events in the production process, such as new job insertions, order cancellations, worker absences, and machine breakdowns. Emerging digital twin (DT) technology can help detect disturbances by continuously comparing physical space with virtual space and triggering a rescheduling policy immediately after a disturbance. This enables dynamic scheduling and greatly reduces the deviation between preschedules and actual schedules. This study focuses on a DT-enabled integrated optimisation problem of flexible job shop scheduling and flexible preventive maintenance (PM) considering both machine and worker resources. A double-layer Q-learning algorithm (DLQL) is designed as the underlying key optimisation method to simultaneously learn the selection process of machines and operations to achieve efficient real-time scheduling. The superior solution performance of DLQL was verified by comparing it with two well-known metaheuristic algorithms and a single-layer Q-learning algorithm under several benchmarks. Furthermore, different disturbance settings were designed to illustrate the DLQL-based dynamic scheduling process in detail. The proposed reinforcement learning (RL)-driven DT enables efficient collaborative scheduling between production and maintenance departments and helps manufacturing companies improve the real-time decision-making process under uncertain perturbations.","Title: A Rectal CT Tumor Segmentation Method Based on Improved U-Net\nYear: 2022\n\nAbstract: Automatic and accurate segmentation of tumor area from rectal CT image plays an extremely key role in the treatment and diagnosis of rectal cancer. This paper proposes the MR-U-Net network model. The improvement is that a pair of encoder and decoder is added longitudinally to the U-shaped structure, which is the network structure of the fifth layer, and a residual module is added horizontally to the encoder and decoder of each layer. This model is used to conduct targeted research on the automatic segmentation method of rectal cancer. [H. Gao et al., Rectal tumor segmentation method based on U-Net improved model, J. Comput. Appl. 40 (8) (2020) 2392-2397] also improved U-Net and used the same dataset as this paper, but the Dice coefficient of all targets was only 83.15%, and the Dice coefficient of small targets was only 87.17%. This paper evaluates the improved MR-U-Net network model with the three indicators of precision, recall and Dice coefficient, and finds that in comparison to Ref. 4 the precision is 95.13%, 2.29% higher than the former work, recall is 94.28%, higher than the former work by 0.34%, Dice coefficient of all targets is 88.45%, increased by 5.3% compared with the former work, and the small targets Dice coefficient is increased by 1.28%, which is the best optimization state of this paper. Experiments show that for datasets with extremely skewed positive and negative samples, the MR-U-Net network structure after improving the hyperparameters in the optimizer can more accurately segment the rectal CT tumor lesion area.","Title: MSL-Net: An Efficient Network for Building Extraction from Aerial Imagery\nYear: 2022\n\nAbstract: There remains several challenges that are encountered in the task of extracting buildings from aerial imagery using convolutional neural networks (CNNs). First, the tremendous complexity of existing building extraction networks impedes their practical application. In addition, it is arduous for networks to sufficiently utilize the various building features in different images. To address these challenges, we propose an efficient network called MSL-Net that focuses on both multiscale building features and multilevel image features. First, we use depthwise separable convolution (DSC) to significantly reduce the network complexity, and then we embed a group normalization (GN) layer in the inverted residual structure to alleviate network performance degradation. Furthermore, we extract multiscale building features through an atrous spatial pyramid pooling (ASPP) module and apply long skip connections to establish long-distance dependence to fuse features at different levels of the given image. Finally, we add a deformable convolution network layer before the pixel classification step to enhance the feature extraction capability of MSL-Net for buildings with irregular shapes. The experimental results obtained on three publicly available datasets demonstrate that our proposed method achieves state-of-the-art accuracy with a faster inference speed than that of competing approaches. Specifically, the proposed MSL-Net achieves 90.4%, 81.1% and 70.9% intersection over union (IoU) values on the WHU Building Aerial Imagery dataset, Inria Aerial Image Labeling dataset and Massachusetts Buildings dataset, respectively, with an inference speed of 101.4 frames per second (FPS) for an input image of size 3 x 512 x 512 on an NVIDIA RTX 3090 GPU. With an excellent tradeoff between accuracy and speed, our proposed MSL-Net may hold great promise for use in building extraction tasks.","Title: A Multiscale and Multitask Deep Learning Framework for Automatic Building Extraction\nYear: 2022\n\nAbstract: Detecting buildings, segmenting building footprints, and extracting building edges from high-resolution remote sensing images are vital in applications such as urban planning, change detection, smart cities, and map-making and updating. The tasks of building detection, footprint segmentation, and edge extraction affect each other to a certain extent. However, most previous works have focused on one of these three tasks and have lacked a multitask learning framework that can simultaneously solve the tasks of building detection, footprint segmentation and edge extraction, making it difficult to obtain smooth and complete buildings. This study proposes a novel multiscale and multitask deep learning framework to consider the dependencies among building detection, footprint segmentation, and edge extraction while completing all three tasks. In addition, a multitask feature fusion module is introduced into the deep learning framework to increase the robustness of feature extraction. A multitask loss function is also introduced to balance the training losses among the various tasks to obtain the best training results. Finally, the proposed method is applied to open-source building datasets and large-scale high-resolution remote sensing images and compared with other advanced building extraction methods. To verify the effectiveness of multitask learning, the performance of multitask learning and single-task training is compared in ablation experiments. The experimental results show that the proposed method has certain advantages over other methods and that multitask learning can effectively improve single-task performance."],"string":"[\n \"Title: Truth-Telling Reservations\\nYear: 2008\\n\\nAbstract: We present a mechanism for reservations of bursty resources that is both truthful and robust. It consists of option contracts whose pricing structure induces users to reveal the true likelihoods that they will purchase a given resource. Users are also allowed to adjust their options as their likelihood changes. This scheme helps users save cost and the providers to plan ahead so as to reduce the risk of under-utilization and overbooking. The mechanism extracts revenue similar to that of a monopoly provider practicing temporal pricing discrimination with a user population whose preference distribution is known in advance.\",\n \"Title: A variant of TNFR2-Fc fusion protein exhibits improved efficacy in treating experimental rheumatoid arthritis.\\nYear: 2010\\n\\nAbstract: Etanercept, a TNF receptor 2-Fc fusion protein, is currently being used for the treatment of rheumatoid arthritis (RA). However, 25% to 38% of patients show no response which is suspected to be partially due to insufficient affinity of this protein to TNF alpha. By using computational protein design, we found that residue W89 and E92 of TNFR2 were critical for ligand binding. Among several mutants tested, W89Y/E92N displayed 1.49-fold higher neutralizing activity to TNFa, as compared to that of Etanercept. Surface plasmon resonance (SPR) based binding assay revealed that the equilibrium dissociation constant of W89Y/E92N to TNFa was 3.65-fold higher than that of Etanercept. In a rat model of collagen-induced arthritis (CIA), W89Y/E92N showed a significantly better ability than Etanercept in reducing paw swelling and improvement of arthritic joint histopathologically. These data demonstrate that W89Y/E92N is potentially a better candidate with improved efficacy in treating RA and other autoimmune diseases.\",\n \"Title: Crowdsourcing, attention and productivity\\nYear: 2008\\n\\nAbstract: We show through an analysis of a massive data set from YouTube that the productivity exhibited in crowdsourcing exhibits a strong positive dependence on attention, measured by the number of downloads. Conversely, a lack of attention leads to a decrease in the number of videos uploaded and the consequent drop in productivity, which in many cases asymptotes to no uploads whatsoever. Moreover, short-term contributors compare their performance to the average contributor芒聙聶s performance while long-term contributors compare it to their own media.\",\n \"Title: Novelty And Collective Attention\\nYear: 2007\\n\\nAbstract: The subject of collective attention is central to an information age where millions of people are inundated with daily messages. It is thus of interest to understand how attention to novel items propagates and eventually fades among large populations. We have analyzed the dynamics of collective attention among 1 million users of an interactive web site, digg.com, devoted to thousands of novel news stories. The observations can be described by a dynamical model characterized by a single novelty factor. Our measurements indicate that novelty within groups decays with a stretched-exponential law, suggesting the existence of a natural time scale over which attention fades.\",\n \"Title: How Public Opinion Forms\\nYear: 2008\\n\\nAbstract: No aspect of the massive participation in content creation that the web enables is more evident than in the countless number of opinions, news and product reviews that are constantly posted on the Internet. Given their importance we have analyzed their temporal evolution in a number of scenarios. We have found that while ignorance of previous views leads to a uniform sampling of the range of opinions among a community, exposure of previous opinions to potential reviewers induces a trend following process which leads to the expression of increasingly extreme views. Moreover, when the expression of an opinion is costly and previous views are known, a selection bias softens the extreme views, as people exhibit a tendency to speak out differently from previous opinions. These findings are not only robust but also suggest simple procedures to extract given types of opinions from the population at large.\",\n \"Title: Popularity, novelty and attention\\nYear: 2008\\n\\nAbstract: We analyze the role that popularity and novelty play in attracting the attention of users to dynamic websites. We do so by determining the performance of three different strategies that can be utilized to maximize attention. The first one prioritizes novelty while the second emphasizes popularity. A third strategy looks myopically into the future and prioritizes stories that are expected to generate the most clicks within the next few minutes. We show that the first two strategies should be selected on the basis of the rate of novelty decay, while the third strategy performs sub-optimally in most cases. We also demonstrate that the relative performance of the first two strategies as a function of the rate of novelty decay changes abruptly around a critical value, resembling a phase transition in the physical world.\",\n \"Title: Texture classification of aerial image based on Bayesian networks with hidden nodes\\nYear: 2007\\n\\nAbstract: Bayesian networks have emerged in recent years as a powerful data mining technique for handling uncertainty in Artificial Intelligence community. However, researchers in the classification area were not interested in Bayesian networks until the simplest kind of Bayesian networks, Naive Bayes Classifiers (NBC), came forth. From that time on, their success led to a recent furry of algorithms for learning Bayesian networks from raw data and triggered experts to explore more deeply into Bayesian networks as classifiers. Although many of learners produce good results on some benchmark data sets, there are still several problems: nodes ordering requirement, computational complexity, lack of publicly available learning tools. Therefore, this paper puts up a new method, Bayesian networks with hidden nodes, which adds some hidden nodes between correlated feature variables to Bayesian networks based on the maximal covariance criterion. Experimental results demonstrate that the proposed method is efficient and effective, and outperforms NBC and Bayesian Network Augmented Naive Bayes (BAN).\",\n \"Title: Persistence and Success in the Attention Economy\\nYear: 2009\\n\\nAbstract: A hallmark of the attention economy is the competition for the attention of\\nothers. Thus people persistently upload content to social media sites, hoping\\nfor the highly unlikely outcome of topping the charts and reaching a wide\\naudience. And yet, an analysis of the production histories and success dynamics\\nof 10 million videos from \\\\texttt{YouTube} revealed that the more frequently an\\nindividual uploads content the less likely it is that it will reach a success\\nthreshold. This paradoxical result is further compounded by the fact that the\\naverage quality of submissions does increase with the number of uploads, with\\nthe likelihood of success less than that of playing a lottery.\",\n \"Title: Antecedents and Outcomes of E-Procurement Adoption: An Integrative Model\\nYear: 2007\\n\\nAbstract: Organizations increasingly emphasize the use of information technology in the procurement process. An integrative model of e-procurement adoption that captures its antecedents, two types of e-procurement use, and their respective effects on relationship development and perceived efficiency gains are proposed and empirically tested using the data collected from senior managers in four technology-intensive industries. Our findings indicate that the use of coordination e-procurement applications has both direct and indirect effects on perceived efficiency gains, while transactional application use can directly lead to efficiency gains. In addition, the use of e-procurement applications is strongly influenced by organizational learning ability and normative pressures. The findings provide a new perspective for managers in their future implementation of e-procurement applications.\",\n \"Title: Harvesting Collective Intelligence: Temporal Behavior in Yahoo Answers\\nYear: 2010\\n\\nAbstract: When harvesting collective intelligence, a user wishes to maximize the\\naccuracy and value of the acquired information without spending too much time\\ncollecting it. We empirically study how people behave when facing these\\nconflicting objectives using data from Yahoo Answers, a community driven\\nquestion-and-answer site. We take two complementary approaches. We first study\\nhow users behave when trying to maximize the amount of the acquired\\ninformation, while minimizing the waiting time. We identify and quantify how\\nquestion authors at Yahoo Answers trade off the number of answers they receive\\nand the cost of waiting. We find that users are willing to wait more to obtain\\nan additional answer when they have only received a small number of answers;\\nthis implies decreasing marginal returns in the amount of collected\\ninformation. We also estimate the user's utility function from the data. Our\\nsecond approach focuses on how users assess the qualities of the individual\\nanswers without explicitly considering the cost of waiting. We assume that\\nusers make a sequence of decisions, deciding to wait for an additional answer\\nas long as the quality of the current answer exceeds some threshold. Under this\\nmodel, the probability distribution for the number of answers that a question\\ngets is an inverse Gaussian, which is a Zipf-like distribution. We use the data\\nto validate this conclusion.\",\n \"Title: Route optimisation models and algorithms for hazardous materials transportation under different environments\\nYear: 2013\\n\\nAbstract: This study focuses on how to determine the optimum transportation route for hazardous materials under the certain, fuzzy or stochastic environment. On the basis of analysing the transportation route selection problem of hazardous materials TRSP-HM, three objectives are presented and the multi-objective routing programming model MRPM for hazardous materials transportation HMT is put forward under the certain environment, and an improved label algorithm is proposed to solve the MRPM. After defining the maximum-chance optimum route and the α-optimum routes, the multi-objective routing chance-constrained programming model MRCPM and multi-objective routing dependent-chance programming model MRDPM for HMT under the fuzzy or stochastic environment are established respectively. Then, the integration intelligent algorithm is developed to solve the proposed models, which integrates the fuzzy simulation, neural networks, stochastic simulation and genetic algorithm. Finally, the proposed models and algorithms are successfully tested with the help of two real cases.\",\n \"Title: The equilibrium generalized assignment problem and genetic algorithm.\\nYear: 2012\\n\\nAbstract: The well-known generalized assignment problem (GAP) is to minimize the costs of assigning n jobs to m capacity constrained agents (or machines) such that each job is assigned to exactly one agent. This problem is known to be NP-hard and it is hard from a computational point of view as well. In this paper, follows from practical point of view in real systems, the GAP is extended to the equilibrium generalized assignment problem (EGAP) and the equilibrium constrained generalized assignment problem (ECGAP). A heuristic equilibrium strategy based genetic algorithm (GA) is designed for solving the proposed EGAP. Finally, to verify the computational efficiency of the designed GA, some numerical experiments are performed on some known benchmarks. The test results show that the designed GA is very valid for solving EGAP.\",\n \"Title: Predicting defect priority based on neural networks\\nYear: 2010\\n\\nAbstract: Existing defect management tools provide little information on how important/urgent for developers to fix defects reported. Manually prioritizing defects is time-consuming and inconsistent among different people. To improve the efficiency of troubleshooting, the paper proposes to employ neural network techniques to predict the priorities of defects, adopt evolutionary training process to solve error problems associated with new features, and reuse data sets from similar software systems to speed up the convergence of training. A framework is built up for the model evaluation, and a series of experiments on five different software products of an international healthcare company to demonstrate the feasibility and effectiveness.\",\n \"Title: Ensuring trust in one time exchanges: solving the QoS problem\\nYear: 2005\\n\\nAbstract: We describe a pricing structure for the provision of IT services that ensures trust without requiring repeated interactions between service providers and users. It does so by offering a pricing structure that elicits truthful reporting of QoS by providers while making them profitable. This mechanism also induces truth-telling on the part of users reserving the service.\",\n \"Title: Human Speed-Accuracy Tradeoffs in Search\\nYear: 2011\\n\\nAbstract: When foraging for information, users face a tradeoff between the accuracy and value of the acquired information and the time spent collecting it, a problem which also surfaces when seeking answers to a question posed to a large community. We empirically study how people behave when facing these conflicting objectives using data from Yahoo Answers, a community driven question-and-answer site. We first study how users behave when trying to maximize the amount of acquired information while minimizing the waiting time. We find that users are willing to wait longer for an additional answer if they have received a small number of answers. We then assume that users make a sequence of decisions, deciding to wait for an additional answer as long as the quality of the current answer exceeds some threshold. The resulting probability distribution for the number of answers that a question gets is an inverse Gaussian, a fact that is validated by our data.\",\n \"Title: Public Discourse in the Web Does Not Exhibit Group Polarization\\nYear: 2008\\n\\nAbstract: We performed a massive study of the dynamics of group delibera- tion among several websites containing millions of opinions on topics ranging from books to media. Contrary to the common phenomenon of group polarization observed offline, we measured a strong tendency towards moderate views in the course of time. This phenomenon possi- bly operates through a self-selection bias whereby previous comments and ratings elicit contrarian views that soften the previous opinions.\",\n \"Title: Design And Implementation Of Ontology-Based Query Expansion For Information Retrieval\\nYear: 2007\\n\\nAbstract: In Information Retrieval (IR), the user's input query conditions usually are not detailed enough, so the satisfactory query results can not be brought back. Query expansion of IR can help to solve this problem. However, the common query expansion in IR cannot get steady retrieval results. In this paper, we propose and implement query expansion method which combines domain ontology with the frequent of terms. Ontology is used to describe domain knowledge; logic reasoner and the frequency of terms arc used to choose fitting expansion words. By this way, higher recall and precise can be gotten as user' query results. Experimental results show that compared with the results of common query expansion, the method described in this paper can get statistically significant improvement in recall and precise combination.\",\n \"Title: Opinion formation under costly expression\\nYear: 2010\\n\\nAbstract: Opinions play an important role in trust building and the creation of consensus about issues and products and a number of studies have focused on the design, evaluation, and utilization of online opinion systems. However, little effort has been spent on the dynamic aspects of online opinion formation. In this article, we study the dynamics of online opinion expression by analyzing the temporal evolution of vey large sets of user views and determine that in the course of time, later opinions tend to show a big difference with earlier opinions, which moderates the average opinion to the less extreme. Online posters also tend to disagree with previous opinions when the cost of expression is high.\",\n \"Title: Coastal erosion mapping through intergration of SAR and Landsat TM imagery\\nYear: 2013\\n\\nAbstract: It is important to monitor long-term coastal erosion in countries such as Australia given the majority of our population live in coastal regions. However, ground-based surveys are labour-intensive and involve significant cost when large spatial areas need to monitored. This paper presents a complementary, cost-effective approach for mapping the eroded shoreline, through integrating Landsat multispectral (MS) imagery data and synthetic aperture radar (SAR) imagery data. This integration method overcomes the problem of data shortage associated with using a single data source. Moreover, it can extract the instant land-water interface at sub-pixel resolution. Because the extracted land-water boundaries are dynamic, a tidal model has to be applied to define the high water line. Wavelet transform and linear spectral unmixing are the two major algorithms used for extracting the land-water interface. Several inundated areas are identified at the selected study area along the coast of East Gippsland Basin, Victoria, Australia. Naturally occurring erosion is believed to be the major factor for these inundated areas. Theoretically the extracted shorelines for defining erosion can reach 1m - 2m resolution approximately.\",\n \"Title: SSIS: Ontology-Based Analyzing and Reasoning of the Shanghai World Expo Knowledge\\nYear: 2009\\n\\nAbstract: As a scheduled World Expo in the grand tradition of international fairs and expositions, Shanghai World Expo (SWE) has recently gained much attention for its highly sophisticated online vision called \\\"Online Expo Shanghai\\\". In this context, researchers are working to provide intelligent mechanisms to SWE. To support intelligent SWE managements and services, SWE modeling is an essential requirement to understand current (and future) large scale international exhibitions and to possibly drive more complex intelligent actions. In this paper, based on the knowledge representation technique of ontology modeling, we introduce the SWE ontology specifying of SWE's domain knowledge. It precisely describes the definition and basic hierarchical rules, properties, relations and instances of SWE; furthermore, a set of domain-specific axioms is derived from the specified classes and slots. The axiom repository is used for consistency checking and knowledge reasoning. It is viewed as the semantic base for SWE information services, and also the primary part of the SWE semantic inquire system (SSIS). We also briefly describe the top architecture of SSIS in which the SWE related knowledge inquiring services are contained and will be evaluated together with SSIS in a practical application project.\",\n \"Title: Classifier assessment and feature selection for recognizing short coding sequences of human genes.\\nYear: 2012\\n\\nAbstract: With the ever-increasing pace of genome sequencing, there is a great need for fast and accurate computational tools to automatically identify genes in these genomes. Although great progress has been made in the development of gene-finding algorithms during the past decades, there is still room for further improvement. In particular, the issue of recognizing short exons in eukaryotes is still not solved satisfactorily. This article is devoted to assessing various linear and kernel-based classification algorithms and selecting the best combination of Z-curve features for further improvement of the issue. Eight state-of-the-art linear and kernel-based supervised pattern recognition techniques were used to identify the short (21-192 bp) coding sequences of human genes. By measuring the prediction accuracy, the tradeoff between sensitivity and specificity and the time consumption, partial least squares (PLS) and kernel partial least squares (KPLS) algorithms were verified to be the most optimal linear and kernel-based classifiers, respectively. A surprising result was that, by making good use of the interpretability of the PLS and the Z-curve methods, 93 Z-curve features were proved to be the best selective combination. Using them, the average recognition accuracy was improved as high as 7.7% by means of KPLS when compared with what was obtained by the Fisher discriminant analysis using 189 Z-curve variables (Gao and Zhang, 2004). The used codes are freely available from the following approaches (implemented in MATLAB and supported on Linux and MS Windows): (1) SVM: http://www.support-vector-machines.org/SVM_soft.html. (2) GP: http://www.gaussianprocess.org. (3) KPLS and KFDA: Taylor, J.S., and Cristianini, N. 2004. Kernel Methods for Pattern Analysis. Cambridge University Press, Cambridge, UK. (4) PLS: Wise, B. M., and Gallagher, N. B. 2011. PLS-Toolbox for use with MATLAB: ver 1.5.2. Eigenvector Technologies, Manson, WA. Supplementary Material for this article is available at www.liebertonline.com/cmb.\",\n \"Title: The economics of attention: maximizing user value in information-rich environments\\nYear: 2008\\n\\nAbstract: We introduce an automatic configuration mechanism that generates the most relevant information to be presented to limited attention users of information-rich media. It also guarantees to maximize their total expected utility from the information they receive. A computationally efficient algorithm is used to assign an index value to each information item, which then determines whether or not a given item appears in the top list presented to users at a given time.\",\n \"Title: A delay-optimized universal FPGA routing architecture\\nYear: 2009\\n\\nAbstract: A universal FPGA routing Architecture is presented, which ensures that every module in the FPGA including CLBs and IOBs have a uniform interconnect architecture, and the load of interconnect lines is equally distributed. So, this architecture is highly repeatable and the signal delay is predictable and regular. Furthermore, the realization of the Programmable Interconnect Point (PIP) and the BUFFER driver is also optimized to benefit the signal delay up to 5%. The test results of the example chip show the reasonableness of these ideas.\",\n \"Title: Networked Control With Reset Quantized State Based on Bernoulli Processing\\nYear: 2014\\n\\nAbstract: This paper considers the problem of reset quantized state control for a class of continuous-time linear system. The logarithmic quantization scheme is employed in the network-based information communication, and a reset state observer is introduced which is based on the standard one to suppress sensor quantization effects. A Bernoulli processing approach is presented to reset the value of the observer with a random way in continuous-time domain. The resulting reset error system is a class of hybrid system which contains both discrete-time and continuous-time stochastic error dynamics. By the stochastic Lyapunov method, it is derived that the error system under the proposed reset technique is asymptotically stable in the sense of each discrete “reset” time instant, and mean-square stable in the continuous-time domain except those “reset” time instants. The observer and controller gains of the closed-loop systems are obtained via solving linear matrix inequalities. Finally, a numerical example is provided to illustrate the effectiveness of the proposed approach.\",\n \"Title: Fault Detection and Diagnosis in Process Data Using Support Vector Machines.\\nYear: 2014\\n\\nAbstract: For the complex industrial process, it has become increasingly challenging to effectively diagnose complicated faults. In this paper, a combined measure of the original Support Vector Machine (SVM) and Principal Component Analysis (PCA) is provided to carry out the fault classification, and compare its result with what is based on SVM-RFE (Recursive Feature Elimination) method. RFE is used for feature extraction, and PCA is utilized to project the original data onto a lower dimensional space. PCA T-2, SPE statistics, and original SVM are proposed to detect the faults. Some common faults of the Tennessee Eastman Process (TEP) are analyzed in terms of the practical system and reflections of the dataset. PCA-SVM and SVM-RFE can effectively detect and diagnose these common faults. In RFE algorithm, all variables are decreasingly ordered according to their contributions. The classification accuracy rate is improved by choosing a reasonable number of features.\",\n \"Title: Detection Method for Credibility Defect of Simulation Based on Sobol' Method and Orthogonal Design.\\nYear: 2013\\n\\nAbstract: Against the defect detection problem of simulation credibility, a method based on Sobolspi0215e method and orthogonal design is proposed. Firstly, taking acceptable range of simulation credibility as measurement standard, then credible indexes and incredible indexes of simulation system are determined. Secondly, experiment scheme is arranged according to an extended table transformed from orthogonal table, and incredible indexspi0215es defect rank is judged by experimental result analysis combining with membership function of defect rank. Thirdly, Latin Hypercube sampling is taken from relevant indexes of incredible index, and then sensitivity coefficients of relevant indexes are calculated using Sobolspi0215e method. Finally an example is given to validate the effectiveness of the proposed method. © Springer-Verlag Berlin Heidelberg 2013.\",\n \"Title: Feedback Loops of Attention in Peer Production\\nYear: 2009\\n\\nAbstract: A significant percentage of online content is now published and consumed via the mechanism of crowdsourcing. While any user can contribute to these forums, a disproportionately large percentage of the content is submitted by very activeand devoted users, whose continuing participation is key to thesites’ success. As we show, people’s propensity to keep participating increases the more they contribute, suggesting motivating factors which increase over time. This paper demonstrates that submitters who stop receiving attention tend to stop contributing, while prolific contributors attract an ever increasing number offollowers and their attention in a feedback loop. We demonstrate that this mechanism leads to the observed power law in the number of contributions per user and support our assertions by an analysis of hundreds of millions of contributions to top content sharing websites Digg.com and Youtube.com.\",\n \"Title: A novel SPDF ensemble classifier for cancer classification\\nYear: 2013\\n\\nAbstract: To gain more accurate and reliable cancer classification results through DNA microarray analysis, a novel ensemble classifier SPDF (Subspace Partial least square based Decision Forest) is developed. The original data are split into subspaces by column. For each subspace, partial least square (PLS) is applied to extract orthogonal latent variables (LVs). In conjunction with the Minimal Redundancy and Maximal Relevance (MRMR) as the gene-selection preprocessing method, the adverse effect of the too high dimensional variables with too small samples could be overcome successfully. Then, all available LVs are aggregated as the new training data where the Decision Forest is trained for classification. Therefore relying on the feature extraction power of PLS and the orthogonality of LVs, the multi-colinearity and high noise inherent in microarray data could be eliminated effectively. Moreover, the Decision Forest could enhance the data variety and further lighten the dependence of the classification results to the given data. The applications to two microarray datasets show that compared with Rotation Forest, Bagging and Boosting, the new SPDF method yields consistently accurate and robust predictive performance, with the maximal improvement reaching 7.26% in terms of classification accuracy on the Colon cancer classification.\",\n \"Title: Study on urban three-lane mixed traffic flow with buses based on the Nagel-Schreckenberg model\\nYear: 2013\\n\\nAbstract: On the basis of Nagel-Schreckenberg NaSch traffic flow model, a new Three-lane Fuzzy Cellular Automaton TFCA model for mixed traffic with buses is established. In our study, the fuzzy control rules are used to determine the random parameters which are capable of describing the mixed traffic flow, especially the braking rate, lane change rules, overtaking and random slow mechanisms of buses are reset just for analysis of psychological factors of bus drivers. Finally the developed TFCA model has been validated by using computer simulation. The results show that the model could be used to reveal the essence of urban three-lane mixed traffic flow characteristics.\",\n \"Title: A Novel Spatial Clustering with Obstacles Constraints Based on Genetic Algorithms and K-Medoids\\nYear: 2006\\n\\nAbstract: Spatial clustering is an important research topic in Spatial Data Mining (SDM). Many methods have been proposed in the literature, but few of them have taken into account constraints that may be present in the data or constraints on the clustering. These constraints have significant influence on the results of the clustering process of large spatial data. In this paper, we discuss the problem of spatial clustering with obstacles constraints and propose a novel spatial clustering method based on Genetic Algorithms (GAs) and KMedoids, called GKSCOC, which aims to cluster spatial data with obstacles constraints. It can not only give attention to higher local constringency speed and stronger global optimum search, but also get down to the obstacles constraints and practicalities of spatial clustering. The results on real datasets show that it is better than standard GAs and K-Medoids.\",\n \"Title: Bootstrapping the Long Tail in Peer to Peer Systems\\nYear: 2005\\n\\nAbstract: Abstract We describe an e‐cient incentive mechanism for P2P systems that generates a wide diversity of content ofierings while responding adaptively to customer demand.,Files are served and paid for through a parimutuel market similar to that used for betting in horse races and in lotteries. An analysis of the performance of such a system shows that there exists an equilibrium with a long tail in the distribution of content ofierings, which guarantees the real time provision of any content regardless of its popularity.\",\n \"Title: A simulated annealing for multi-criteria optimization problem: DBMOSA.\\nYear: 2014\\n\\nAbstract: This paper investigates a simulated annealing (SA) for multi-criteria optimization problem (MOP) which incorporates the concept of archive in order to provide a set of tradeoff solutions for the problem under consideration. To determine the acceptance probability of a new solution, an evaluation measure of multi-criteria objective function is proposed which takes into account the dominant relation between the new and current solutions, as well as those in the archive. In addition, a mutation operator is proposed in which the constraints of MOP can be partially handled. To efficiently apply the proposed SA into constrained MOP (CMOP), an equivalent relaxation approach is proposed by which the CMOP, say primal problem, can be equivalently transformed into an unconstrained MOP, say relaxation problem. Based on such a constraints handling technique (CHT), it is theoretically proved that the primal problem and the relaxation problem have the same efficient set (ES) and the proposed CHT is then further extended into two existing multi-criteria optimization (MO) evolutionary algorithms (EA) (MOEA), say AMOSA and NSGA-II, respectively. Two performance metrics are proposed to evaluate the performance of the MOEAs. Finally, a comprehensive comparative study among AMOSA, NSGA-II and the proposed SA is performed on some popular benchmarks for MOP algorithms to show the effectiveness of the proposed SA and CHT. The comparative study shows that the overall performance of the proposed SA is generally superior to both of the AMOSA and NSGA-II, particularly, for the MOPs with three objectives the performance of the former is far better than the latter, and the proposed CHT can be very conveniently extended into any of the existing EAs for MOP such that they can be applied to solve the CMOPs.\",\n \"Title: Proportional response dynamics leads to market equilibrium\\nYear: 2007\\n\\nAbstract: One of the main reasons of the recent success of peer to peer (P2P)file sharing systems such as BitTorrent is their built-in tit-for-tat mechanism. In this paper, we model the bandwidth allocation in a P2P system as an exchange economy and study a tit-for-tat dynamics, namely the proportional response dynamics, in this economy. In aproportional response dynamics each player distributes its good to its neighbors proportional to the utility it received from them in thelast period. We show that this dynamics not only converges but converges to a market equilibrium, a standard economic characterization of efficient exchanges in a competitive market. In addition, for some classes of utility functions we consider, it converges much faster than the classical tat process and any existingalgorithms for computing market equilibria. As a part of our proof we study the double normalization of a matrix, an operation that linearly scales the rows of a matrix sothat each row sums to a prescribed positive number, followed by a similar scaling of the columns. We show that the iterative double normalization process of any non-negative matrix always converges. This complements the previous studies in matrix scaling that has focused on the convergence condition of the process when the row and column normalizations are considered as separate steps.\",\n \"Title: Multi-objective fuzzy optimisation method for emergency evacuation based on hybrid intelligence algorithm under fuzzy environment\\nYear: 2013\\n\\nAbstract: After a sudden public event, how to optimise emergency evacuation routings and enhance the response capability of emergency system is an important issue for emergency management agency. In this paper, we choose the optimal evacuation routing under fuzzy environment to make sure the injured reach the destination safely and quickly. Chance-constrained programming model of emergency evacuation routings and chance-dependent constraint programming models are setup respectively and a hybrid intelligence algorithm is designed to solve the model. The algorithm, which combines simulation technique and the genetic algorithm, produces chromosomes according to priority-based coding mode, uses simulation technique to calculate target values of chromosomes, produces a new group by using improved roulette wheel method to select chromosomes, crosses by adopting the partially matched crossover method, and uses reciprocal exchange mutation method to mutate. Finally, an example is presented to validate the feasibility of this model and the algorithm. The research result can help emergency decision-makers to find an optimal route after a sudden public event and reduce the casualties caused by transportation delays.\",\n \"Title: Latent Ringlike Road Traffic Control System Based On Compound Mechanism Particle Swarm Optimisation Algorithm\\nYear: 2013\\n\\nAbstract: Urban traffic congestion is one of the most severe problems of everyday life in many cities. In an effort to deal with this problem, traffic control system technologies have concentrated in recent years on dealing with urban congestion. In the paper, a compound mechanism particle swarm optimisation (CMPSO) algorithm has been proposed, and the algorithm has been effectively used in dealing with the optimisation of city latent ringlike road traffic control system. In the algorithm, the tabu search algorithm and the particle swarm algorithm are combined effectively, and the tabu can offset the local optimums and avoid searching one solution repeatedly. Simulations show the CMPSO algorithm cannot only avoid premature convergence effectively, but also has powerful optimisation ability and higher precision. It makes the rate of delay and numbers of stopping reduce obviously.\",\n \"Title: Quantized H output feedback control for linear discrete-time systems\\nYear: 2013\\n\\nAbstract: This paper investigates the robust H∞ dynamic output feedback control problem for networked control systems (NCSs) with quantized measurements. The measurement losses of the communicated information are considered in an unreliable communication channel. The robust H∞ dynamic output feedback controllers are designed to handle the measurement losses and mitigate the quantization effects such that the resultant closed-loop NCS is mean-square stochastically stable with a prescribed H∞ disturbance attenuation performance. The controller existence conditions can be derived in terms of linear matrix inequalities (LMIs). Finally, an example is provided to illustrate the effectiveness of the proposed approach.\",\n \"Title: Steel plates fault diagnosis on the basis of support vector machines.\\nYear: 2015\\n\\nAbstract: Fault diagnosis is always a big concern in industry production. As industrial technology has developed a lot, new fault diagnosis methods are needed to distinguish faults with only fine distinctions. The higher quality a production is required to have, the better fault diagnosis method the factories should apply. A fault diagnosis method based on modified Support Vector Machines (SVMs) is shown in this paper. With this method, dimension of samples is effectively reduced by recursive feature elimination (RFE) algorithm, and computing time is saved at the same time. Besides, classification accuracy is improved by parameter optimizing and sample size balancing strategy. A faults dataset of steel plates is taken as a practical case. And SVMs that are modified by different algorithms are utilized to complete fault diagnosis. This combined measure shows its superiority in sorting common faults of steel plates over original SVMs. Some essential procedures in model developing, such as normalization and cross validation, are also referred to.\",\n \"Title: Step-wise support vector machines for classification of overlapping samples\\nYear: 2015\\n\\nAbstract: mong machine learning algorithms, Support Vector Machine (SVM) is outstanding for its high efficiency and good generalization ability. This paper mainly concerns the classification performance of SVMs for multiple classes and auxiliary algorithms combined with SVMs. These auxiliary algorithms include Recursive Feature Elimination (RFE) algorithm, parameters optimizing methods and Two-Step Classification strategy. Results are given under data-based framework that classification ability and operation efficiency of SVMs are both improved when dimension is reduced; and Two-Step Classification SVM (TSC-SVM) works well under circumstances that samples overlap with each other seriously. In TSC-SVM, differences between adjacent samples are denoised by wavelet transform and magnified by a proper weighting function, after samples are sorted into correct groups in the first step. Discussions and comparisons are based on abalone dataset. According to the simulations, it is believed that step-wise SVMs have superior classification ability.\",\n \"Title: A person-environment-object model for data acquisition method of microscopic behavior\\nYear: 2014\\n\\nAbstract: Behavior research is limited by the accessibility of the microscopic behavior data. In this study, a PEO (Person-Environment-Object) model is proposed to decompose the diverse microscopic behavior in real world into simple and measurable variables such as position, status, time, and etc., which serves as a foundation for the behavioral data collection. According to the PEO model, then the framework of acquisition program for microscopic behavior data is established based on wireless sensor technology, in order to provide high spatial and temporal resolution behavioral data for deep behavior research and its applications.\",\n \"Title: Orientation measurement based on magnetic inductance by the extended distributed multi-pole model.\\nYear: 2014\\n\\nAbstract: This paper presents a novel method to calculate magnetic inductance with a fast-computing magnetic field model referred to as the extended distributed multi-pole (eDMP) model. The concept of mutual inductance has been widely applied for position/orientation tracking systems and applications, yet it is still challenging due to the high demands in robust modeling and efficient computation in real-time applications. Recently, numerical methods have been utilized in design and analysis of magnetic fields, but this often requires heavy computation and its accuracy relies on geometric modeling and meshing that limit its usage. On the other hand, an analytical method provides simple and fast-computing solutions but is also flawed due to its difficulties in handling realistic and complex geometries such as complicated designs and boundary conditions, etc. In this paper, the extended distributed multi-pole model (eDMP) is developed to characterize a time-varying magnetic field based on an existing DMP model analyzing static magnetic fields. The method has been further exploited to compute the mutual inductance between coils at arbitrary locations and orientations. Simulation and experimental results of various configurations of the coils are presented. Comparison with the previously published data shows not only good performance in accuracy, but also effectiveness in computation.\",\n \"Title: Sequential systems of linear equations algorithm for nonlinear optimization problems--general constrained problems\\nYear: 2004\\n\\nAbstract: In Ref. [J. Comput. Math. 20 (3) (2002) 301], a new superlinearly convergent algorithm of sequential systems of linear equations for nonlinear optimization problems with inequality constraints was proposed. Since the new algorithm only needs to solve four systems of linear equations having a same coefficient matrix per iteration, the computation amount of the algorithm is much less than that of the existing sequential quadratic programming algorithms per iteration. Under some mild assumptions, the new algorithm is globally convergent and its rate of convergence is one-step superlinearly. In this paper, it is shown that the new algorithm also can be used to deal with nonlinear optimization problems having nonlinearly equality and inequality constraints, by solving an auxiliary problem. Some numerical results are reported.\",\n \"Title: Support vector regression based approach for key index forecasting with applications\\nYear: 2015\\n\\nAbstract: With the rapid development in science and technology, data acquisition, storage and mining technology are widely applied to various fields. All aspects of people's lives are recorded as data. Through the analyzing and arranging of data, people can get a lot of valuable information. In this paper, support vector machine (SVM), least squares support vector machine (LSSVM) and partial least squares (PLS) are respectively used in the field of economic research. Real-time monitoring and forecasting for stock index is vital to the market. The changing trend and index of stocks are predicted according to the analysis to the history data of the stock. By combining particle swarm algorithm (PSO) algorithm and LSSVM algorithm, the parameters in the LSSVM model can be optimized. These algorithms are compared on the basis of their forecasting results.\",\n \"Title: A New Simplification Approach Based on the Oblique-Dividing-Curve Method for Contour Lines.\\nYear: 2016\\n\\nAbstract: As one of the key operators of automated map generalization, algorithms for the line simplification have been widely researched in the past decades. Although many of the currently available algorithms have revealed satisfactory simplification performances with certain data types and selected test areas, it still remains a challenging task to solve the problems of (a) how to properly divide a cartographic line when it is too long to be dealt with directly; and (b) how to make adaptable parameterizations for various geo-data in different areas. In order to solve these two problems, a new line-simplification approach based on the Oblique-Dividing-Curve (ODC) method has been proposed in this paper. In this proposed model, one cartographic line is divided into a series of monotonic curves by the ODC method. Then, the curves are categorized into different groups according to their shapes, sizes and other geometric characteristics. The curves in different groups will trigger different strategies as well as the associated criteria for line simplification. Whenever a curve is simplified, the whole simplified cartographic line will be re-divided and the simplification process restarts again, i.e., the proposed simplification approach is iteratively operated until the final simplification result is achieved. Experiment evidence demonstrates that the proposed approach is able to handle the holistic bend-trend of the whole cartographic line during the simplification process and thereby provides considerably improved simplification performance with respect to maintaining the essential shape/salient characteristics and keeping the topological consistency. Moreover, the produced simplification results are not sensitive to the parameterizations of the proposed approach.\",\n \"Title: A Spatial Conditioned Latin Hypercube Sampling Method for Mapping Using Ancillary Data.\\nYear: 2016\\n\\nAbstract: For obtaining maps of good precision by the spatial inference method, the distribution of sampling sites in geographical and feature space is very important. For a regional variable with trends, the predicting error comes from trend estimation, variogram estimation and spatial interpolation. Based on the cLHS (conditioned Latin hypercube Sampling) method, a sampling method called scLHS (spatial cLHS) considering all these three aspects with the help of ancillary data is proposed in this article. Its advantage lies in simultaneously improving trend estimation, variogram estimation and spatial interpolation. MODIS data and simulated data were used as sampling fields to draw sample sets using scLHS, cLHS, cLHS with x and y coordinates as covariates, simple random and spatial even sampling methods, and the distribution and prediction errors of sample sets from different methods were evaluated. The results showed that scLHS performed well in balancing spreading in geographic and feature space, and can generate points pairs with small distances, and the sample sets drawn by scLHS produced smaller mapping error, especially when there were trends in the target variable.\",\n \"Title: A Compact Magnetic Field-Based Obstacle Detection and Avoidance System for Miniature Spherical Robots.\\nYear: 2017\\n\\nAbstract: Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical robots, yet very limited studies have been conducted regarding the obstacle avoidance capability of spherical robots. Most of the existing spherical robots rely on the \\\"hit and run\\\" technique, which has been argued to be a reasonable strategy because spherical robots have an inherent ability to recover from collisions. Without protruding components, they will not become stuck and can simply roll back after running into bstacles. However, for small scale spherical robots that contain sensitive surveillance sensors and cannot afford to utilize heavy protective shells, the absence of obstacle avoidance solutions would leave the robot at the mercy of potentially dangerous obstacles. In this paper, a compact magnetic field-based obstacle detection and avoidance system has been developed for miniature spherical robots. It utilizes a passive magnetic field so that the system is both compact and power efficient. The proposed system can detect not only the presence, but also the approaching direction of a ferromagnetic obstacle, therefore, an intelligent avoidance behavior can be generated by adapting the trajectory tracking method with the detection information. Design optimization is conducted to enhance the obstacle detection performance and detailed avoidance strategies are devised. Experimental results are also presented for validation purposes.\",\n \"Title: Quality Assessment Method for Linear Feature Simplification Based on Multi-Scale Spatial Uncertainty.\\nYear: 2017\\n\\nAbstract: This study discusses a method for quantitative quality assessment for the simplification of linear features. Considering the multi-scale nature of linear features, this paper combines the improved Douglas-Peucker method without threshold and the multiway tree model to construct a weighted hierarchical linear feature representation model called the Douglas-Peucker Multiway Tree (DMC-tree). Subsequently, the uncertainty computation is conducted from the root of the DMC-Tree top-down level by level to obtain the quality indexes. Then, the quality index of the whole linear feature is obtained by combining the indexes of every layer together with their weights. The results of the presented method are compared with those of the length ratio method and the Hausdorff distance method. The results show the advantages of the presented method over the others, including (1) its sensitivity to feature points of multiple scales, (2) the quantitative characteristics of the indexes, and (3) the finer granularity in assessment.\",\n \"Title: Does research on digital public relations indicate a paradigm shift? An analysis and critique of recent trends.\\nYear: 2017\\n\\nAbstract: •Imbalanced attention to social media from academia and practitioners.•Digital PR studies are gradually shifting from description to theorization.•Methodological diversification needs to continue for robust digital PR research.•Organizational perspective dominates, with increasing attention to NPOs.\",\n \"Title: A Progressive Method of Simplifying Polylines with Multi-bends Simplification Templates.\\nYear: 2017\\n\\nAbstract: Polyline simplification is one of the most important and classic researches in multi-scale expression of cartography and GIS. Polyline simplification methods based on bend units get widespread attention recently. Having analyzed the bends composing characteristics and the manual simplification process of polylines, it is resonable to find that not all of invisible bend units are deleted directly. A new progressive simplification method based on multi-bends groups is proposed. Firstly, based on the threshold of the simplified scale, polylines are divided into multi-bends groups. Secondly, in order to avoid over-simplification, some reasonable bends deletion options which called multi-bends templates are proposed. However multi-bends templates is not steady and always related to the quantity of multi-bends uniquely. Considering of the minimal errors derived form polyline simplification, the best multi-bends template that result in the least displacement is selected to simplify muli-bends groups. Thirdly, polylines do not stop repeating the above two steps until all bend units of simplified polylines can be detected in the simplified scale. Experiments with real road-net data were implemented, and comparison with other algorithms is discussed. Results show advantages including: (i) The proposed algorithm is a progressive simplification process which is conform to human cognition. (ii) The proposed algorithm can preserve the main shape of the polyline with deleting invisible bend units enough. (iii) The proposed algorithm avoid unnecessary displacement by deleting bend units as little possible.\",\n \"Title: Co-design of event generator and state estimator for complex network systems with quantization.\\nYear: 2016\\n\\nAbstract: This paper studies the problem of event-triggered state estimation for complex network systems with quantization. The event-triggered communication scheme and quantization are employed to reduce the burden of network transmission. By utilizing Lyapunov stability theory and linear matrix inequality techniques, sufficient conditions are established which can ensure the augmented estimation error system to be asymptotically stable. Furthermore, the explicit expressions of the desired state estimators are derived in terms of linear matrix inequalities. Finally, an example is provided to illustrate the usefulness of the proposed method.\",\n \"Title: Shape Similarity Assessment Method for Coastline Generalization.\\nYear: 2018\\n\\nAbstract: Although shape similarity is one fundamental element in coastline generalization quality, its related research is still inadequate. Consistent with the hierarchical pattern of shape recognition, the Dual-side Bend Forest Shape Representation Model is presented by reorganizing the coastline into bilateral bend forests, which are made of continuous root-bends based on Constrained Delaunay Triangulation and Convex Hull. Subsequently, the shape contribution ratio of each level in the model is expressed by its area distribution in the model. Then, the shape similarity assessment is conducted on the model in a top-down layer by layer pattern. Contrast experiments are conducted among the presented method and the Length Ratio, Hausdorff Distance and Turning Function, showing the improvements of the presented method over the others, including (1) the hierarchical shape representation model can distinguish shape features of different layers on dual-side effectively, which is consistent with shape recognition, (2) its usability and stability among coastlines and scales, and (3) it is sensitive to changes in main shape features caused by coastline generalization.\",\n \"Title: Evaluation and Application of Fuzzy Factors in Road Network Selection\\nYear: 2018\\n\\nAbstract: Road's weights are vital in road network selection, as they can represent the relative importance of the roads among the road network. In the existing algorithms, three types of characteristics of roads, i.e. geometrical, topological and distribution characteristics, have been taken into account as the measure of roads' weights. But there are other characteristics such as traffic flow, economical value or culture value may affect the roads' importance in road networks, which are called fuzzy factors in the new algorithm because they are usually difficulty to measure by a certain value. To fill this gap, the paper propose a new algorithm take into account these fuzzy factors during road network selection. The basic idea is as follows: 1) fuzzy factors which should be taken into consideration in the process of road networks selection are proposed, and a comprehensive evaluation is made on these fuzzy factors; 2) the evaluated result is introduced into the road network selection. Experiment shows that the new algorithm taking into account the fuzzy factors not only inherits the advantages of the existing algorithm, but also considers the factors which are ignored in the existing algorithms, the selection results are more reasonable and in line with people's actual needs.\",\n \"Title: A Mobile Application for Dog Breed Detection and Recognition Based on Deep Learning\\nYear: 2018\\n\\nAbstract: Deep learning provides the ability to train algorithms (models) that can tackle the problems of data classification and prediction based on deriving (learning) knowledge from raw data. Convolutional Neural Networks (CNNs) provides one commonly used approach for image classification and detection. In this work we describe a CNN-based method for detecting dogs in potentially complex images and subsequently consider the identification of the type/breed of dogs. The results achieve nearly 85% accuracy for breed classification for a set of 50 classes of dogs and 64% accuracy for 120 other less common dog types. An iOS application and associated big data processing infrastructure utilizing a variety of GPUs was used to support the image classification algorithms.\",\n \"Title: An Algorithm based on the Weighted Network Voronoi Diagram for Point Cluster Simplification.\\nYear: 2019\\n\\nAbstract: Points on maps that stand for geographic objects such as settlements are generally connected by road networks. However, in the existing algorithms for point cluster simplification, points are usually viewed as discrete objects or their distances are considered in Euclidean spaces, and therefore the point cluster generalization results obtained by these algorithms are sometimes unreasonable. To take roads into consideration so that point clusters can be simplified in appropriate ways, the network Voronoi diagram is used and a new algorithm is proposed in this paper. First, the weighted network Voronoi diagram is constructed taking into account the weights of the points and the properties of the related road segments. Second, the network Voronoi polygons are generated and two factors (i.e., the area of the network Voronoi polygon and the total length of the dilated road segments in the polygon) are considered as the basis for point simplification. Last, a Cartesian coordinate system is built based on the two factors and the point clusters are simplified by means of the \\\"concentric quadrants\\\". Our experiments show that the algorithm can effectively and correctly transmit types of information in the process of point cluster simplification, and the results are more reasonable than that generated by the ordinary Voronoi-based algorithm and the weighted Voronoi-based algorithm.\",\n \"Title: Collision-aware Task Assignment for Multi-Robot Systems\\nYear: 2019\\n\\nAbstract: We propose a novel formulation of the collision-aware task assignment (CATA) problem and a decentralized auction-based algorithm to solve the problem with optimality bound. Using a collision cone, we predict potential collisions and introduce a binary decision variable into the local reward function for task bidding. We further improve CATA by implementing a receding collision horizon to address the stopping robot scenario, i.e. when robots are confined to their task location and become static obstacles to other moving robots. The auction-based algorithm encourages the robots to bid for tasks with collision mitigation considerations. We validate the improved task assignment solution with both simulation and experimental results, which show significant reduction of overlapping paths as well as deadlocks.\",\n \"Title: Extracting Main Center Pattern from Road Networks Using Density-Based Clustering with Fuzzy Neighborhood\\nYear: 2019\\n\\nAbstract: The spatial pattern is a kind of typical structural knowledge that reflects the distribution characteristics of object groups. As an important semantic pattern of road networks, the city center is significant to urban analysis, cartographic generalization and spatial data matching. Previous studies mainly focus on the topological centrality calculation of road network graphs, and pay less attention to the delineation of main centers. Therefore, this study proposes an automatic recognition method of main center pattern in road networks. We firstly extract the main clusters from road nodes by improving the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) with fuzzy set theory. Moreover, the center area is generated with road meshes according to the area ratio with the covering discs of the main clusters. This proposed algorithm is applied to the road networks of a monocentric city and polycentric city respectively. The results show that our method is effective for identifying the main center pattern in the road networks. Furthermore, the contrast experiments demonstrate our method's higher accuracy.\",\n \"Title: Pattern Recognition Of Complex Distributed Ditches\\nYear: 2021\\n\\nAbstract: The ditch pattern reflects the distribution characteristics of an agricultural drainage system and needs to be detected to enrich the data source before map generalization. Due to several breaks, the connectivity of the ditches is destroyed between ditches and rivers in map representation, making its structure complex. Previous studies have primarily focused on extracting parallel ditches, paying less attention to complex ditches with breaks. The pattern recognition of ditches does not merely involve the extraction of parallel relation. It involves the extraction of different level relations, which is a great challenge. Therefore, this study proposes a novel model to describe the complex structure of ditches. Our work consisted of the following three main contributions: (1) the collinear relation was defined to detect the groups of ditch segments separated by breaks, (2) the detection method of parallel relation was improved throughout the multi-parameter combined constraints, and (3) the main-tributary relation was proposed to build a connection between parallel groups and rivers. The experimental results showed that the proposed method was solved effectively in complex ditch pattern recognition.\",\n \"Title: Finite-time passivity and synchronization of coupled complex-valued memristive neural networks\\nYear: 2021\\n\\nAbstract: The finite-time passivity and finite-time synchronization issues for two categories of coupled complex-valued memristive neural networks with and without time-varying delay are discussed. First, by selecting a suitable control scheme and exploiting some inequality techniques, several finite-time passivity conditions are proposed for coupled complex-valued memristive neural networks without time-varying delay. Based on the obtained finite-time passivity condition, a criterion for finite-time synchronization for the considered network is also established. Furthermore, for coupled complex-valued memristive neural networks with time-varying delay, some criteria are established to guarantee that the considered network is finite-time passive and finite-time synchronized by developing an appropriate controller and deploying the Lyapunov functional method. Finally, two numerical examples with simulations substantiate the correctness and validity of the results.\",\n \"Title: Finite-time synchronization and H∞ synchronization of coupled complex-valued memristive neural networks with and without parameter uncertainty\\nYear: 2022\\n\\nAbstract: In this paper, finite-time synchronization and H∞ synchronization of coupled complex-valued memristive neural networks (CCVMNNs) with or without parameter uncertainty are analyzed. First, a finite-time synchronization (FTS) condition is presented for CCVMNNs by means of deploying Lyapunov stability theory and developing suitable controllers. Then, we utilize the similar method to derive a criterion of robust finite-time synchronization (RFTS) for the proposed CCVMNNs with uncertain parameter. Furthermore, we establish some criteria for the sake of ensuring that the considered network can reach finite-time H∞ synchronization and robust finite-time H∞ synchronization. At last, two numerical examples with simulations demonstrate the validity of the acquired results.\",\n \"Title: Direct Sparse Odometry With Planes\\nYear: 2022\\n\\nAbstract: We propose a novel formulation to use plane primitives in the direct sparse odometry formulation. Unlike existing SLAM works that introduce geometric error terms to account for planes, our method keeps the full error as purely photometric. The proposed system exploits the segmentation masks and plane parameters from a deep neural network and jointly optimizes the camera poses, 3D points, and 3D planes. The tightly-coupled formulation improves the pose estimation by fusing information on high-level geometric primitives and also refines the outputs of the plane detection network during optimization.\",\n \"Title: Complex Fluctuation of Power Price in Dual-Channel and Multienergy Supply Chain Based on Sticky Expectation\\nYear: 2021\\n\\nAbstract: According to the current power supply focused reform in China, a dual-channel and multienergy supply chain model is constructed. The supply chain has a new energy enterprise, a traditional energy enterprise, and the State Grid that is the retailer. New energy company and traditional energy company sell electricity to the State Grid at wholesale prices, and at the same time they enter the market to retail power products. Multiequilibriums and their practical significance are discussed. The complex dynamic is investigated using a bifurcation diagram, Lyapunov exponent, parameter basin, and fractal dimension. In this multilayer supply chain network, the price adjustment of the State Grid will make the entire supply chain face greater volatility risks, and dual-channel suppliers, that is, new energy and traditional energy companies are also involved in this volatility. Further, considering the sticky information, the sticky expectation of electricity price is built for studying the lagging electricity price. The dynamic characteristics of the sticky model are investigated, and new phenomena are discovered: 3-orbit bifurcation and mutation appear with fractals. This means that prices continue to swing and oscillate on three tracks. Through comparison of the fractal dimension, an important conclusion is discovered: the purpose of sticky expectations for electricity prices is to stabilize price fluctuations, but sticky expectations make the market more complicated. The article provides a strategic reference for exploring the power market in China.\",\n \"Title: Sliding Bifurcation in Planar Piecewise Smooth Systems with Two Zones Separated by an Ellipse\\nYear: 2021\\n\\nAbstract: The objective of this paper is to study the sliding bifurcation in a planar piecewise smooth system with an elliptic switching curve. Some new phenomena are observed, such as a crossing limit cycle containing four intersections with the switching curve, sliding cycles having four sliding segments, and sliding cycles consisting of the entire switching curve. Firstly, we investigate the bifurcation of sliding cycle from a sliding heteroclinic connection to two cusps and show the appearance of one sliding cycle with two folds. To plot the bifurcation diagram, a planar piecewise linear system with two zones separated by an ellipse are considered. Moreover, we study in more detail the unfolding of a sliding cycle connecting four cusps by exhibiting its complete bifurcation diagram. More precisely, we explore the necessary and sufficient conditions for the existence of limit cycles and derive the concrete bifurcation curves. Additionally, a simple piecewise smooth system with nonlinear subsystems is studied, which shows the possibility of the existence of two nested limit cycles. Finally, numerical simulations are given to confirm the theoretical analysis.\",\n \"Title: Noise Error Pattern Generation Based on Successive Addition-Subtraction for GRAND-MO\\nYear: 2022\\n\\nAbstract: Guessing random additive noise decoding (GRAND) is a capacity-approaching universal algorithm. The GRAND Markov order (GRAND-MO) variant is effective to correct burst errors in a Markov chain modeled memory channel, and the core of GRAND-MO is to generate putative noise error patterns in MO effectively. For purpose of a uniform noise error pattern generation scheme of GRAND-MO, this letter propose...\",\n \"Title: Digital twin-enabled dynamic scheduling with preventive maintenance using a double-layer Q-learning algorithm\\nYear: 2022\\n\\nAbstract: Dynamic scheduling methods are essential and critical to manufacturing systems because of uncertain events in the production process, such as new job insertions, order cancellations, worker absences, and machine breakdowns. Emerging digital twin (DT) technology can help detect disturbances by continuously comparing physical space with virtual space and triggering a rescheduling policy immediately after a disturbance. This enables dynamic scheduling and greatly reduces the deviation between preschedules and actual schedules. This study focuses on a DT-enabled integrated optimisation problem of flexible job shop scheduling and flexible preventive maintenance (PM) considering both machine and worker resources. A double-layer Q-learning algorithm (DLQL) is designed as the underlying key optimisation method to simultaneously learn the selection process of machines and operations to achieve efficient real-time scheduling. The superior solution performance of DLQL was verified by comparing it with two well-known metaheuristic algorithms and a single-layer Q-learning algorithm under several benchmarks. Furthermore, different disturbance settings were designed to illustrate the DLQL-based dynamic scheduling process in detail. The proposed reinforcement learning (RL)-driven DT enables efficient collaborative scheduling between production and maintenance departments and helps manufacturing companies improve the real-time decision-making process under uncertain perturbations.\",\n \"Title: A Rectal CT Tumor Segmentation Method Based on Improved U-Net\\nYear: 2022\\n\\nAbstract: Automatic and accurate segmentation of tumor area from rectal CT image plays an extremely key role in the treatment and diagnosis of rectal cancer. This paper proposes the MR-U-Net network model. The improvement is that a pair of encoder and decoder is added longitudinally to the U-shaped structure, which is the network structure of the fifth layer, and a residual module is added horizontally to the encoder and decoder of each layer. This model is used to conduct targeted research on the automatic segmentation method of rectal cancer. [H. Gao et al., Rectal tumor segmentation method based on U-Net improved model, J. Comput. Appl. 40 (8) (2020) 2392-2397] also improved U-Net and used the same dataset as this paper, but the Dice coefficient of all targets was only 83.15%, and the Dice coefficient of small targets was only 87.17%. This paper evaluates the improved MR-U-Net network model with the three indicators of precision, recall and Dice coefficient, and finds that in comparison to Ref. 4 the precision is 95.13%, 2.29% higher than the former work, recall is 94.28%, higher than the former work by 0.34%, Dice coefficient of all targets is 88.45%, increased by 5.3% compared with the former work, and the small targets Dice coefficient is increased by 1.28%, which is the best optimization state of this paper. Experiments show that for datasets with extremely skewed positive and negative samples, the MR-U-Net network structure after improving the hyperparameters in the optimizer can more accurately segment the rectal CT tumor lesion area.\",\n \"Title: MSL-Net: An Efficient Network for Building Extraction from Aerial Imagery\\nYear: 2022\\n\\nAbstract: There remains several challenges that are encountered in the task of extracting buildings from aerial imagery using convolutional neural networks (CNNs). First, the tremendous complexity of existing building extraction networks impedes their practical application. In addition, it is arduous for networks to sufficiently utilize the various building features in different images. To address these challenges, we propose an efficient network called MSL-Net that focuses on both multiscale building features and multilevel image features. First, we use depthwise separable convolution (DSC) to significantly reduce the network complexity, and then we embed a group normalization (GN) layer in the inverted residual structure to alleviate network performance degradation. Furthermore, we extract multiscale building features through an atrous spatial pyramid pooling (ASPP) module and apply long skip connections to establish long-distance dependence to fuse features at different levels of the given image. Finally, we add a deformable convolution network layer before the pixel classification step to enhance the feature extraction capability of MSL-Net for buildings with irregular shapes. The experimental results obtained on three publicly available datasets demonstrate that our proposed method achieves state-of-the-art accuracy with a faster inference speed than that of competing approaches. Specifically, the proposed MSL-Net achieves 90.4%, 81.1% and 70.9% intersection over union (IoU) values on the WHU Building Aerial Imagery dataset, Inria Aerial Image Labeling dataset and Massachusetts Buildings dataset, respectively, with an inference speed of 101.4 frames per second (FPS) for an input image of size 3 x 512 x 512 on an NVIDIA RTX 3090 GPU. With an excellent tradeoff between accuracy and speed, our proposed MSL-Net may hold great promise for use in building extraction tasks.\",\n \"Title: A Multiscale and Multitask Deep Learning Framework for Automatic Building Extraction\\nYear: 2022\\n\\nAbstract: Detecting buildings, segmenting building footprints, and extracting building edges from high-resolution remote sensing images are vital in applications such as urban planning, change detection, smart cities, and map-making and updating. The tasks of building detection, footprint segmentation, and edge extraction affect each other to a certain extent. However, most previous works have focused on one of these three tasks and have lacked a multitask learning framework that can simultaneously solve the tasks of building detection, footprint segmentation and edge extraction, making it difficult to obtain smooth and complete buildings. This study proposes a novel multiscale and multitask deep learning framework to consider the dependencies among building detection, footprint segmentation, and edge extraction while completing all three tasks. In addition, a multitask feature fusion module is introduced into the deep learning framework to increase the robustness of feature extraction. A multitask loss function is also introduced to balance the training losses among the various tasks to obtain the best training results. Finally, the proposed method is applied to open-source building datasets and large-scale high-resolution remote sensing images and compared with other advanced building extraction methods. To verify the effectiveness of multitask learning, the performance of multitask learning and single-task training is compared in ablation experiments. The experimental results show that the proposed method has certain advantages over other methods and that multitask learning can effectively improve single-task performance.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":66,"string":"66"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":278,"string":"278"}}},{"rowIdx":279,"cells":{"question_id":{"kind":"string","value":"Wentong Cai"},"question":{"kind":"string","value":"Generate an abstract for the title \"Hybrid modelling of crowd simulation\" using the following items: 1. Crowd simulation \n2. Macroscopic and microscopic modeling \n3. Hybrid modelling method \n4. Efficiency and accuracy \n5. Case study"},"answer":{"kind":"string","value":"Macroscopic and microscopic modeling have become mainstream methodologies for crowd simulation in dynamic environments. The two models make a trade-off between efficiency and accuracy, but neither of them is able to achieve both goals at the same time. With the aim of achieving both efficiency and accuracy, a hybrid modelling method is proposed in this paper for crowd simulation. This paper illustrates how the two types of models co-exist in a single simulation and work collaboratively. A case study for this method is also conducted, the simulation result of which shows that the proposed method can not only benefit from the macroscopic model by improving the simulation efficiency, but also obtain a fine-grained simulation result by adopting the microscopic model."},"correct_answer":{"kind":"string","value":"Macroscopic and microscopic modeling have become mainstream methodologies for crowd simulation in dynamic environments. The two models make a trade-off between efficiency and accuracy, but neither of them is able to achieve both goals at the same time. With the aim of achieving both efficiency and accuracy, a hybrid modelling method is proposed in this paper for crowd simulation. This paper illustrates how the two types of models co-exist in a single simulation and work collaboratively. A case study for this method is also conducted, the simulation result of which shows that the proposed method can not only benefit from the macroscopic model by improving the simulation efficiency, but also obtain a fine-grained simulation result by adopting the microscopic model."},"documents":{"kind":"list like","value":["Title: File allocation with balanced response time in a distributed multi-server information system\nYear: 1998\n\nAbstract: As information systems move from centralized to distributed systems, the distribution of the data files among the servers becomes a major issue. This paper reports on the results of a heuristic algorithm that is used to distribute the files among multiple heterogeneous servers interconnected by a fast network. The objective of our algorithm is to minimize the differences between response times of the servers (or in other words, to minimize the response imbalance factor). The servers are modeled using M/M/1 queues. In this paper, we first describe the problem, then the algorithm is presented and its bounds on the imbalance factor analyzed. The characteristics of our algorithm are also studied through simulation. Results are compared with the algorithms proposed by other researchers, which show a considerable improvement in the imbalance factor and only a slight increase in the average response time of the system.","Title: A secure information service for monitoring large scale grids\nYear: 2007\n\nAbstract: The Grid Information Service (GIS) is a core component in the Grid software infrastructure. It provides diverse information to users or other service components in Grid environments. In this paper, we propose a scalable GIS architecture for information management in a large scale Grid Virtual Organization (VO). This architecture consists of the VO layer, site layer and resource layer: at the resource layer, information agents and pluggable information sensors are deployed on each resource monitored. This information agent and sensor approach provides a flexible framework that enables specific information to be captured; at the site layer, a site information service component with caching capability aggregates and maintains up-to-date information of all the resources monitored within an administrative domain; at the VO layer, a peer-to-peer approach is used to build a virtual network of site information services for information discovery and query in a large scale Grid VO. This decentralized approach makes information management scalable and robust. Furthermore, we propose a security framework for the GIS, which provide security policies for authentication and authorization control of the GIS at both the site and the VO layers. Our GIS has been implemented based on the Globus Toolkit 4 as Web services compliant to Web Services Resource Framework (WSRF) specifications. The experimental results show that the GIS presents satisfactory scalability in handling information for large scale Grids.","Title: A utility model for timely state update in distributed wargame simulations\nYear: 2004\n\nAbstract: In distributed wargame simulations, the states of simulation entities need to be updated and sent to other simulation nodes in a timely manner, which may incur high overhead on the network. Thus, how to efficiently use the limited bandwidth of the network is very important to the performance of distributed wargame simulations. In this paper, a utility model is proposed to evaluate the relative importance of a simulation entity. In our proposed utility model, the utility of an entity is determined by the number of entities on which this entity may have influence and the distances between this entity and the entities within its area of influence. Based on the utility model, we may devise some flexible updating mechanisms which can utilize the bandwidth more efficiently. For example, the state updates of an important entity which may have nodes with a high frequency; on the other hand, the state updates of an entity with little importance may be sent to other simulation nodes with a low frequency. In this paper, we will focus on the utility computation of a simulation entity rather than the flexible state updating mechaisms for the simulation entities. Our proposed utility computation mechanism is general and can be easily implemented using the HLA services. Experimental results show that the utility computation mechanism incurs little overhead.","Title: GPU accelerated three-stage execution model for event-parallel simulation.\nYear: 2013\n\nAbstract: This paper introduces the concept of event-parallel discrete event simulation (DES) and its corresponding implementation on the GPU platform. Inspired by the typical spatial-parallel DES and time-parallel DES, the event-parallel approach on GPU uses each thread to process one of the N events, where N is the total number of events. By taking advantage of the high parallelism of GPU threads, this approach achieves greater speedup. The GPU architecture is adopted in the execution of the event-parallel approach, so as to take advantage of the parallel processing capability provided by the massively large number of GPU threads. A three-stage execution model composing of generating events, sorting events and processing events in parallel is proposed. This execution model achieves good speedup. Compared with the event scheduling approach on CPU, we achieve up to 22.80 speedup in our case study.","Title: SOAr-DSGrid: Service-Oriented Architecture for Distributed Simulation on the Grid\nYear: 2006\n\nAbstract: Simulation is a low cost alternative to experimentation on real-world physical systems. Grid technology enables coordinated use of and secure access to distributed computing resources and data sources. The service-oriented architecture (SOA) is an ideal paradigm for next generation computing. The loose coupling among services in the SOA relieves service consumers from detailed knowledge of implementation, implementation language, and execution platform of the services to be consumed. In this paper, we propose a framework for developing a component-based distributed simulation and executing the simulation in a service-oriented architecture on the Grid. This framework consists of the schemas for developing simulation components and simulation applications, and underlying base component service modules for constructing a simulation component as a service. The use of component interfaces and schemas enables collaborative development of simulation applications, and the deployment of simulation components as services takes advantage of the SOA (e.g., loose coupling, heterogeneity, and transport neutrality). This paper discusses the motivation for developing such a framework and describes the details of its development.","Title: Update schedules for improving consistency in multi-server distributed virtual environments.\nYear: 2014\n\nAbstract: Distributed Virtual Environments (DVEs) have been widely used in online games, military training and collaborative engineering applications, etc. In DVEs, the primary task is to maintain a consistent view of the virtual world among all users. Multi-server architecture has been shown to have good scalability to support a large population of users in DVEs. However, servers can still get saturated with network bandwidth due to several reasons. In this case, state updates cannot be disseminated timely and the consistency of the virtual world cannot be guaranteed. This paper investigates update schedules to prioritize state updates from a global perspective for improving consistency in multi-server DVEs where each server has a limit on upload bandwidth. Using time–space inconsistency (TSI) metric, we analyze the problem using Lagrange Multipliers for a DVE in an ideal situation with unchanged configurations and the results are then used to develop an updating algorithm in practical systems. Experimental results show that the proposed algorithm significantly improves the consistency compared to other existing update algorithms.","Title: A framework for executing parallel simulation using RTI\nYear: 2003\n\nAbstract: The grid enables large-scale resource sharing and makes it viable for running large-scale parallel and distributed simulations. The high level architecture (HLA) paradigm provides a software platform and interoperability interface for simulation components to utilize these hardware resources. However, neither the grid nor the HLA provides mechanism for resource management for parallel and distributed simulations. It is also noticed that substantial effort is required for writing program that conforms to the runtime infrastructure (RTI) requirements because of its complexity. In this paper, we introduce a framework for designing and executing parallel simulation using the RTI. The framework is also designed to assist load balancing and checkpointing. With the code library from our framework, the modeler is able to complete the design of a parallel simulation that runs on RTI by specifying the simulation configuration and the handling detail of each event. Our framework incorporates automatic code generation. It also uses data distribution management (DDM) to route simulation events (interactions) to achieve efficient use of network bandwidth.","Title: Design and implementation of an efficient multi-cluster GridRPC system\nYear: 2005\n\nAbstract: Multi-cluster Grids have emerged as the most popular type of grid environments. On multi-cluster grid, resources are distributed across different networks. Hence, scheduling and dispatching jobs are difficult and inefficient due to the restrictions of network and the communication overhead. This paper presents the design and implementation of an efficient GridRPC system for the multi-cluster grid. Metascheduling mechanism is developed to distribute jobs onto different clusters of computers effectively. Further, a dynamic bundling mechanism is provided to reduce overhead of job dispatching. This mechanism bundles similar requests to form a composite request that is dispatched to a grid resource. The above mechanisms have been tested with different types of services and loads, and the results show that they help to achieve more balanced workload and reduce the overhead of job dispatching. This cuts down execution time of applications.","Title: HLA-Based Distributed Simulation Cloning\nYear: 2004\n\nAbstract: Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same simulation execution session. One important goal of the technology is to optimize execution by avoiding repeated computation amongst independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA) based distributed simulations. A decoupled federate architecture is designed to support correct federate cloning at runtime. A federate may spawn clones to explore different scenarios at a decision point. To address the complexity of the overall cloning-enabled distributed simulation due to increasing scenario spawning, we have devised an efficient and precise scheme to identify and partition scenarios. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected while the rest remain intact and are shared amongst the original and new scenarios. Our incremental cloning mechanism ensures accurate sharing and initiates cloning only when strictly necessary.","Title: Algorithms for HLA-based distributed simulation cloning\nYear: 2005\n\nAbstract: Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same execution session. One important goal is to optimize execution by avoiding repeated computation among independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA)-based distributed simulations; a federate may spawn clones to explore different scenarios at a decision point. This article introduces the cloning mechanism and the supporting infrastructure. When enabling cloning, our approach ensures the state consistency and supports user transparency and reusability of federate codes. When a federate clones, it is desirable to replicate only those federates whose states will be affected while the rest are shared among the old and new scenarios. This article discusses the theory and issues involved in such an incremental cloning mechanism, which guarantees accurate sharing and initiates cloning only when absolutely necessary. Experiments have been carried out to compare the performance of entire cloning and incremental cloning mechanisms. Experimental results indicate that the proposed approach provides correct cloning and can significantly reduce the execution time for evaluating different scenarios of a distributed simulation. Moreover the incremental cloning mechanism significantly surpasses entire cloning in terms of execution efficiency.","Title: A prototype of distributed molecular visualization on computational grids\nYear: 2004\n\nAbstract: The architecture and the computational kernels of Simulation of Crossed Molecular Beam Experiments, an Internet portal managing the simulation of elementary bimolecular processes as those occurring in crossed beam apparatuses, is discussed. The construction ...","Title: Collaborative Interest Management for Peer-to-Peer Networked Virtual Environment\nYear: 2011\n\nAbstract: Interest Management (IM) aims at eliminating irrelevant state updates transmitted in Networked Virtual Environment (NVE). The traditional IM mechanisms can be classified into area-based and cell-based mechanisms. Hybrid IM mechanism was proposed recently to reduce the communication overhead by utilizing the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism. Compared to the traditional mechanisms, the hybrid mechanism reduces the upload bandwidth consumption at each player site and thus allows more players to join the virtual environment with today's network capacity. However, it requires each player maintains some global information about all other players. Updating the global information undoubtedly involves communication overhead. This paper proposes a collaborative IM mechanism for peer-to-peer NVEs, which works only relying on each joining player's local knowledge rather than globally available information so as to further reduce the communication cost of IM mechanisms. The performance of our collaborative IM mechanism is evaluated by simulating multiplayer game scenarios and the results are compared with the hybrid IM mechanism as well as the well-established peer-to-peer NVE neighbor discovery mechanism VON.","Title: An Efficient Sort-Based DDM Matching Algorithm for HLA Applications with a Large Spatial Environment\nYear: 2007\n\nAbstract: Simulation is a low cost and safe alternative to solve complex problems in various areas. To promote reuse and interoperability of simulation applications and link geographically dispersed simulation components, distributed simulation was introduced. The High Level Architecture (HLA) is the IEEE standard for distributed simulation. To optimize communication efficiency between simulation components, HLA defines a Data Distribution Management (DDM) service group for filtering out unnecessary data exchange. It relies on the computation of overlap between update and subscription regions, which is called matching. In this paper, we propose an efficient sort-based DDM matching algorithm for HLA applications with a large spatial environment. A theoretical analysis of our algorithm concludes that it should have good storage and computational scalability. The experimental results have verified the theoretical conclusions by showing that our algorithm has much less storage requirement than the original sort-based matching algorithm and generally has the best computational performance when compared with region-based and the original sort-based matching algorithms.","Title: Manufacturing sypply chain management: distributed supply chain simulation across enterprise boundaries\nYear: 2000\n\nAbstract: The effective practice of supply chain management (SCM) is crucial to improve corporations' competitive advantage. Many corporations have built simulation models to facilitate the application of simulation in designing, evaluating, and optimizing their supply chain. Traditionally, a supply chain involves only a single enterprise with multiple facilities and distribution centers. Hence, sharing of detailed simulation models is not a problem in this scenario. But in recent years, the scope of SCM has evolved to cross the enterprise boundaries. Applying simulation in designing, evaluating, and optimizing the supply chain becomes more difficult since the participating corporations might not be willing to share their simulation models with partners. In this paper, distributed simulation techniques are presented as an enabling technology that allows corporations to construct a cross enterprise simulation while hiding model details within the enterprise. This can be realized by either building the simulation on top of the Runtime Infrastructure of the High Level Architecture or building the simulation on top of a customized distributed discrete event simulation protocol. These alternative approaches are compared in terms of their performance and interoperability. The comparison of the performance is done through a benchmarking test of a semiconductor supply chain model.","Title: An auto-adaptive dead reckoning algorithm for distributed interactive simulation\nYear: 1999\n\nAbstract: This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately handle the dynamic relationships between moving entities, a multi-level threshold scheme is proposed. The definition of threshold levels is based on the concepts of area of interest (AOI) and sensitive region (SR), and the levels of threshold are adaptively adjusted based on the relative distance between entities during the simulation. Various experiments were conducted. The results show that the proposed auto-adaptive dead reckoning algorithm can achieve considerable reduction in update packets without sacrificing accuracy in extrapolation","Title: Grid-based partitioning for large-scale distributed agent-based crowd simulation\nYear: 2012\n\nAbstract: Agent-based crowd simulation, which aims to simulate large crowds of autonomous agents with realistic behavior, is a challenging but important problem. One key issue is scalability. Parallelism and distribution is an obvious approach to achieve scalability for agent-based crowd simulation. Parallel and distributed agent-based crowd simulation, however, introduces its own challenges, in particular, effectively distributing workload amongst multiple nodes with minimal overhead. In order to ensure effective distribution with low overhead, a proper partitioning mechanism is required. Generally, human crowds consist of groups or exhibit particular patterns of flow, which are then reflected in simulations. Exploiting this grouping with an appropriate partitioning mechanism should enable efficient distribution of crowd simulation. In this paper we introduce a grid-based clustering algorithm which we compare to previous clustering approaches that used the K-means algorithm.","Title: Evaluation of Java thread performance on two different multithreaded kernels\nYear: 1999\n\nAbstract: Modern programming languages and operating systems encourage the use of threads to exploit concurrency and simplify program structure. An integral and important part of the Java language is its multithreading capability. Despite the portability of Java threads across almost all platforms, the performance of Java threads varies according to the multithreading support of the underlying operating system and the way Java Virtual Machine maps Java threads to the native system threads. In this paper, a well-known compute-intensive benchmark, the EP benchmark, was used to examine various performance issues involved in the execution of threads on two different multithreaded platforms: Windows NT and Solaris. Experiments were carried out to investigate thread creation and computation behavior under different system loads, and to explore execution features under certain extreme situations such as the concurrent execution of very large number of Java threads. Some of the experimental results obtained from threads were compared with a similar implementation using processes. These results show that the performance of Java threads differs depending on the various mechanisms used to map Java threads to native system threads, as well as on the scheduling policies for these native threads. Thus, this paper provides important insights into the behavior and performance of Java threads on these two platforms, and highlights the pitfalls that may be encountered when developing multithreaded Java programs.","Title: An Information Service for Grid Virtual Organization: Architecture, Implementation and Evaluation\nYear: 2005\n\nAbstract: Information Service is the heart of the entire Grid software infrastructure. It maintains various information in a Grid environment, and provides this information to users on request. We present an Information Service architecture for information capturing, aggregation, and provisioning in a Grid Virtual Organization (VO). This Information Service is a hierarchical structure which consists of VO layer, site layer and resource layer. The architecture defines downloadable and pluggable information sensors for portability and flexibility of information capturing. The meta-data mechanism is incorporated into our Information Service for information organization and management. Experiments were conducted to evaluate the performance of the Information Service, and the results show that the Information Service presents satisfactory scalability with number of users and number of information amount. Our Information Service has been implemented based on the Globus Toolkit as a Grid service compliant to the Open Grid Services Architecture (OGSA) specifications.","Title: A peer-to-peer approach to task scheduling in computation grid\nYear: 2005\n\nAbstract: Most of the existing solutions on task scheduling and resource management in grid computing are based on the traditional client/server\n model, enforcing a homogenous policy on making decisions and limiting the system flexibility and scalability. In this paper,\n we propose a peer-to-peer (P2P)-based decentralized approach, which off-loads the intermediate server by letting the peers\n in the grid to make the scheduling decision among themselves using their own scheduling policies. A generic architecture for\n metascheduler on peers, called PGS (P2P Grid Scheduler), and the task scheduling framework based on PGS have been developed. Both push and pull modes are used for distributing\n the tasks to peers with the support of load balancing and fault tolerance. A prototype of the proposed architecture and mechanism\n has been developed and simple performance tests have been conducted.","Title: A Generic Symbiotic Simulation Framework\nYear: 2006\n\nAbstract: A symbiotic or online simulation is defined as one that interacts with the physical system in a mutually beneficial way. The simulation is driven by real time data collected from a physical system under control and needs to meet the real-time requirements of the physical system. In turn, the results from the \"what-if\" experiments performed by the simulator can be used to control the dynamic behaviour of the physical system. Such a simulation tool is for real-time planning and is to foresee and advise on real time problems. It aims to improve performance, to adapt to sudden and unexpected events and to improve aspects of safety and security of the physical system.","Title: Determining Optimal Update Period for Minimizing Inconsistency in Multi-server Distributed Virtual Environments\nYear: 2011\n\nAbstract: The primary task of distributed virtual environments (DVEs) is to maintain a consistent view of the virtual world among all users. Multi-server architecture has been shown to have good scalability to support a large population of users in DVEs. However, some of the servers' resources like CPU, memory and network bandwidth can still get saturated as the scale of DVE increases. In this case, state updates cannot be disseminated timely and the consistency of the virtual world cannot be guaranteed. In this paper, we investigate how to efficiently use the limited resources for state update to minimize inconsistency in multi-server DVEs. Using time-space inconsistency metric, we firstly prove that periodic state update will result in minimal inconsistency for each replica. Then, in order to determine the optimal update periods for replicas to minimize the total time-space inconsistency of the DVE, we formulate the problem as a convex optimization problem with inequality constraints. Finally, an interior point method is adopted to solve the problem and the performance is evaluated using simulation results.","Title: Compensatory dead-reckoning-based update scheduling for distributed virtual environments.\nYear: 2013\n\nAbstract: In a distributed virtual environment (DVE), participants located in different places may observe inconsistent views of the simulated virtual world due to message delay and loss in the network. This paper investigates how to compensate for the impact of message delay and loss on consistency in the DVE. We focus on dead reckoning (DR)-based update mechanisms and measure inconsistency by the time-space inconsistency (TSI) metric. We theoretically analyze the TSI of an entity and derive the condition under which the impact of message delay and loss on consistency can be fully compensated for by reducing the DR threshold. Based on the analysis, a compensatory update scheduling algorithm is proposed. Experiments using real traces of a racing car game are conducted to evaluate the compensatory algorithm. The results confirm that if the condition derived in our theoretical analysis is fulfilled, the compensatory algorithm can decrease the TSI of a racing car to the level of the case without message delay and loss when there is sufficient network bandwidth available. Under severe bandwidth constraints, the compensatory algorithm still leads to comparable TSIs of the racing car among the participants regardless of their network conditions so as to enable fair competition.","Title: Hierarchical interest management for distributed virtual environments.\nYear: 2013\n\nAbstract: An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Distributed Virtual Environments (DVE). This paper proposes a new hierarchical IM mechanism for DVEs. The hierarchical mechanism divides the virtual world into multiple levels of cells and keeps the relationship between an entity and an Area-Of-Interest (AOI) at a particular cell level according to their relative position. As their relative position changes, the relationship level is updated accordingly. Compared with the traditional area-based and cell-based mechanisms, the proposed hierarchical mechanism significantly reduces the communication bandwidth consumption of IM and thus considerably improves the scalability of DVEs. In addition, the proposed mechanism also has much lower computation cost than the traditional mechanisms and very acceptable storage requirement for its data structures.","Title: A replication structure for efficient and fault-tolerant parallel and distributed simulations\nYear: 2010\n\nAbstract: Large scale parallel and distributed simulations (federations) are developed to study complex systems. Their executions are usually computationally intensive, involving a large number of simulation components (federates) which may be developed by different participants and executed at different locations. Hence, it is attractive to provide mechanisms which can accelerate the executions and tolerate the failures of federates. Previously, we have proposed a federate replication structure, which improves simulation performance by replicating federates with alternative synchronization approaches and automatically choosing the fastest replica to represent the federate in the federation execution. In this paper, we will extend the replication structure so that it keeps the advantages of performance enhancement in the presence of failures. Besides presenting the design and implementation details, we also report the experimental results to demonstrate that the extended replication structure can provide fault tolerance while maintaining performance advantages for simulation executions.","Title: Interactivity-Constrained Server Provisioning in Large-Scale Distributed Virtual Environments\nYear: 2012\n\nAbstract: Maintaining interactivity is one of the key challenges in distributed virtual environments (DVEs). In this paper, we consider a new problem, termed the interactivity-constrained server provisioning problem, whose goal is to minimize the number of distributed servers needed to achieve a prespecified level of interactivity. We identify and formulate two variants of this new problem and show that they are both NP-hard via reductions to the set covering problem. We then propose several computationally efficient approximation algorithms for solving the problem. The main algorithms exploit dependencies among distributed servers to make provisioning decisions. We conduct extensive experiments to evaluate the performance of the proposed algorithms. Specifically, we use both static Internet latency data available from prior measurements and topology generators, as well as the most recent, dynamic latency data collected via our own large-scale deployment of a DVE performance monitoring system over PlanetLab. The results show that the newly proposed algorithms that take into account interserver dependencies significantly outperform the well-established set covering algorithm for both problem variants.","Title: Distributed Execution Of Workflow Using Parallel Partitioning\nYear: 2009\n\nAbstract: Grid computing is a fundamental technology for large scale distributed resource sharing. Workflow management is becoming one of the most important Grid services. A lot of research work has been done on different issues involved in workflow management systems. The focus of this paper is on three areas: workflow partitioning, enactment and data movement. A new workflow management system called parallel and distributed workflow management system (PDWMS) is proposed. In this system the execution of workflow is done by a network of collaborative engines. To achieve this target, the original abstract workflow (input of the system) is partitioned into parallel parts, using a new proposed partitioning algorithm. PDWMS's data movement, which is categorized into local and global models, uses a peer-to-peer approach.","Title: A virtualization-based approach for zone migration in distributed virtual environments\nYear: 2011\n\nAbstract: This paper deals with the zone migration problem in large-scale distributed virtual environments (DVEs), e.g., massively multi-player online games, distributed military simulations, etc. To support real-time interactions among thousands of concurrent, geographically separated clients, a distributed server architecture is generally needed. In such architecture, the large virtual world can be partitioned into multiple smaller zones, enabling load distributions or zone-to-server mappings to improve interactivity. For example, a zone might be mapped (assigned) to a server location near most of its clients to reduce network latency. In this paper, we consider the problem of live zone migration over wide area networks (WANs) to support DVE zone re-mapping or load re-distribution in a geographically distributed server infrastructure. We propose a virtualization-based zone migration approach, and develop several migration algorithms to effectively migrate multiple DVE zones. We have implemented the proposed migration approach and algorithms in a tool for DVE performance enhancement and monitoring. Extensive experiments have also been conducted with an online multi-player game prototype constructed using the Torque 3D game engine. The results demonstrate the feasibility of our migration approach.","Title: Consistency aware update schedule in multi-server Distributed Virtual Environments\nYear: 2010\n\nAbstract: Multi-server architecture is very popular in Distributed Virtual Environments. Although multi-server architecture has good scalability, the load balance and consistency are still challenging issues. Because of server resource limitations (computation, communication etc), the consistency of the virtual world cannot be guaranteed sometimes. In this paper, we address this problem by developing scheduling polices and try to get better overall consistency with limited resources. We formulate the problem by using integer programming model and propose a centralized approximate algorithm. A distributed update strategy is also developed accordingly. Our algorithm is validated by theoretical analysis and wide range of experiments.","Title: Performance prediction tools for parallel discrete-event simulation\nYear: 1999\n\nAbstract: We have developed a set of performance prediction tools which help to estimate the achievable speedups from parallelizing a sequential simulation. The tools focus on two important factors in the actual speedup of a parallel simulation program: the simulation protocol used; and the inherent parallelism in the simulation model. The first two tools are a performance/parallelism analyzer for a conservative, asynchronous simulation protocol, and a similar analyzer for a conservative, synchronous (super-step) protocol. Each analyzer allows us to study how the speedup of a model changes with increasing number of processors, when a specific protocol is used. The third tool-a critical path analyzer-gives on ideal upper bound to the model's speedup. This paper gives an overview of the prediction tools, and reports the predictions from applying the tools to a discrete-event wafer fabrication simulation model. The predictions are close to speedups from actual parallel implementations. These tools help us to set realistic expectations of the speedup from a parallel simulation program, and to focus our work on issues which are more likely to yield performance improvement","Title: A Decentralized Hierarchical Scheduler for a Grid-Based Clearinghouse\nYear: 2003\n\nAbstract: Grid technologies enable large-scale resource sharing among enterprises and/or individuals. In such settings, control policies must be administered so that resource can be fairly shared among participating enterprises. A grid-based clearinghouse for managing shared resources is built with the aim of promoting technical and scientific cooperation within and between campuses. With that, we need a global mechanism for exchanging and integrating resource and hence, maximize computation throughput through the coordination of shared resources. The major process involved is the development of a job management strategy. In this paper, we will introduce the design and application of a decentralized hierarchical scheduler for job management in the clearinghouse.","Title: Crowd modeling and simulation technologies\nYear: 2010\n\nAbstract: As a collective and highly dynamic social group, the human crowd is a fascinating phenomenon that has been frequently studied by experts from various areas. Recently, computer-based modeling and simulation technologies have emerged to support investigation of the dynamics of crowds, such as a crowd's behaviors under normal and emergent situations. This article assesses the major existing technologies for crowd modeling and simulation. We first propose a two-dimensional categorization mechanism to classify existing work depending on the size of crowds and the time-scale of the crowd phenomena of interest. Four evaluation criteria have also been introduced to evaluate existing crowd simulation systems from the point of view of both a modeler and an end-user. We have discussed some influential existing work in crowd modeling and simulation regarding their major features, performance as well as the technologies used in this work. We have also discussed some open problems in the area. This article will provide the researchers with useful information and insights on the state of the art of the technologies in crowd modeling and simulation as well as future research directions.","Title: Toward a Generic Framework for Modeling Human Behaviors in Crowd Simulation\nYear: 2009\n\nAbstract: This paper presents our ongoing work on modeling agents with human-like decision making and behavior execution capabilities in crowd simulation. We aim to provide a generic framework that reflects the major cognitive and physical processes as observed from human behaviors in real-life situations. The design of the framework is based on some basic assumptions and related cognitive theories on human behaviors in various real-life situations. In this paper, the cognitive architecture of our framework is presented, which emphasizes the role of experiences in human's decision making. The paper also briefly describes the design of agent's decision making process and presents a case study to show some results in a crowd simulation scenario.","Title: An integrated and adaptive decision-support framework for high-tech manufacturing and service networks\nYear: 2005\n\nAbstract: This article describes the results of one of the ten pilot programmes under the Integrated Manufacturing and Service Systems (IMSS) initiative pursued by the Agency for Science, Technology and Research (A* STAR) in Singapore. The objective of this particular programme is to investigate how design, analysis, enhancement and implementation of critical business processes in a manufacturing and service network can be realised using one single simulation/application framework. The overall architecture of the framework outlines how commercial simulation packages and web-service based business process application components would have to be connected through a commercial application framework to achieve maximum leverage and re-usability of the applications involved. In the pilot phase of this programme, research issues were also addressed with regard to mechanisms for interoperation between commercial simulation packages, symbiotic interaction between simulation-based decision support components and physical systems, and simulation speed-up through multi-objective optimal computing budget allocation techniques on a grid infrastructure.","Title: Causal Order Delivery in a Multicast Environment: An Improved Algorithm\nYear: 2002\n\nAbstract: Causal order delivery of messages is required for many distributed applications. One of the problems with causal order delivery algorithms is the need to attach the dependency information with each message to ensure the causal ordering of delivery. This introduces a large amount of overhead and limits the scalability of the algorithm. To reduce the amount of dependency information, an algorithm was proposed by Prakash to attach only direct dependency information to the messages. The algorithm is optimal in a broadcast environment. However, in a multicast environment, it fails to eliminate indirect dependencies in some cases. In this paper, an improved causal order delivery algorithm that eliminates indirect dependencies in a broadcast as well as a multicast environment is proposed. The new algorithm is analyzed against Prakash's algorithm in terms of optimality on eliminating indirect dependencies. Simulation studies were also carried out to compare the performance of the two algorithms. The results show that the new algorithm incurs less communication overhead than Prakash's algorithm in all the cases.","Title: Batch based cancellation: a rollback optimal cancellation scheme in time warp simulations\nYear: 2004\n\nAbstract: An efficient cancellation scheme is essential to the performance of Time Warp simulations. The pitfalls of rollback echoes, chasing hazards and cascading rollbacks can be identified as being attributable to the inefficiency of the conventional per-event based cancellation scheme. Instead of capturing the happen-before relation between events, which is used by the range based cancellation scheme, the batch based cancellation scheme proposed in this paper utilizes a modified paradigm of vector time, namely, state vector, to capture the dependence of events. We prove that with conformance to specific rules regulating the advancement of LPs, the events to be cancelled by a straggler message can be determined using a range of the state vector. Thus, knowledge of the range enables any LP to recover from the receipt of a straggler message at the cost of at most one rollback (i.e., rollback optimal). The results of preliminary experiments conducted using a manufacturing model show that the proposed scheme is successful in reducing the number of anti-messages and increasing the ratio of the number of committed events to the number of processed events.","Title: Agent-based human behavior modeling for crowd simulation\nYear: 2008\n\nAbstract: Human crowd is a fascinating social phenomenon in nature. This paper presents our work on designing behavior model for virtual humans in a crowd simulation under normal-life and emergency situations. Our model adopts an agent-based approach and employs a layered framework to reflect the natural pattern of human-like decision making process, which generally involves a person's awareness of the situation and consequent changes on the internal attributes. The social group and crowd-related behaviors are modeled according to the findings and theories observed from social psychology (e.g., social attachment theory). By integrating our model into an agent execution process, each individual agent can response differently to the perceived environment and make realistic behavioral decisions based on various physiological, emotional, and social group attributes. To demonstrate the effectiveness of our model, a case study has been conducted, which shows that realistic human behaviors can be generated at both individual and group level. Copyright © 2008 John Wiley & Sons, Ltd.","Title: A Hybrid Analysis of an Optimization Approach for Cluster Applications\nYear: 2005\n\nAbstract: Cluster/distributed computing has become a popular, cost-effective alternative to high-performance parallel computers. Many parallel programming languages and related programming models have become widely accepted on clusters. However, the high communication overhead is a major shortcoming of running parallel applications on cluster/distributed computing environments. To reduce the communication overhead and thus the completion time of a parallel application, this paper introduces and evaluates an efficient Key Message (KM) approach to support parallel computing on cluster computing environments. In this paper, we briefly present the model and algorithm, and then analytical and simulation methods are adopted to evaluate the performance of the algorithm. It demonstrates that when network background load increases or the computation to communication ratio decreases, the analysis results show better improvement on communication of a parallel application over the system which does not use the KM approach.","Title: Parallel Federates - An Architecture for Hybrid Distributed Simulation\nYear: 2001\n\nAbstract: Abstract: In High Level Architecture (HLA) based distributed simulation, a federation is a set of federates, where each federate is normally executed sequentially. Our recent work on HLA-based distributed supply chain simulation shows that a federate with well above-par workload will become the performance bottleneck of the entire federation, since faster federates have to wait for the slower one to advance its simulation time. In this paper, we propose a parallel federate architecture which exploits the internal parallelism of a single federate. The parallel federate architecture is an integration of a parallel simulation protocol and HLA-based distributed simulation. A parallel federate can be executed on a SMP system to improve the performance of the entire federation. Our approach gains the advantages of both the interoperability, reusability and scalability of the HLA and faster execution of the parallel simulation protocol.","Title: HumDPM: a decision process model for modeling human-like behaviors in time-critical and uncertain situations\nYear: 2011\n\nAbstract: Generating human-like behaviors for virtual agents has become increasingly important in many applications, such as crowd simulation, virtual training, digital entertainment, and safety planning. One of challenging issues in behavior modeling is how virtual agents make decisions given some time-critical and uncertain situations. In this paper, we present HumDPM, a decision process model for virtual agents, which incorporates two important factors of human decision making in time-critical situations: experience and emotion. In HumDPM, rather than relying on deliberate rational analysis, an agent makes its decisions by matching past experience cases to the current situation. We propose the detailed representation of experience case and investigate the mechanisms of situation assessment, experience matching and experience execution. To incorporate emotion into HumDPM, we introduce an emotion appraisal process in situation assessment for emotion elicitation. In HumDPM, the decision making process of an agent may be affected by its emotional states when: 1) deciding whether it is necessary to do a re-match of experience cases; 2) determining the situational context; and 3) selecting experience cases. We illustrate the effectiveness of HumDPM in crowd simulation. A case study of two typical crowd scenarios is conducted, which shows how a varied crowd composition leads to different individual behaviors, due to the retrieval of different experiences and the variation of agents' emotional states.","Title: Employing economics to achieve fairness in usage policing of cooperatively shared computing resources\nYear: 2005\n\nAbstract: A cooperative virtual organization (VO) is formed when distinct organizations pool their computing and data resources together. In a typical VO, there is no central authority that governs the amount of resources that each organization should contribute to the community. To prevent free-riding on shared resources, we introduce policies to curb excessive usage in an equitable manner. While centralized schemes are simple, they are generally inefficient due to the presence of irregular workload traffic. This paper theoretically demonstrates how under specific conditions, an economy-based framework can be designed to achieve fairness. From our formalization, we conceptually show that agent homogeneity and load-based pricing schemes on shared resources can help achieve this requirement.","Title: Cluster based partitioning for agent-based crowd simulations\nYear: 2009\n\nAbstract: Simulating crowds is a challenging but important problem. There are various methodologies in the literature ranging from macroscopic numerical flow simulations to detailed, microscopic agent simulations. One key issue for all crowd simulations is scalability. Some methods address this issue through abstraction, describing global properties of homogeneous crowds. However, ideally a modeler should be able to simulate large heterogeneous crowds at fine levels of detail. We are attempting to achieve scalability through the application of distributed simulation techniques to agent-based crowd simulation. Distributed simulation, however, introduces its own challenges, in particular how to efficiently partition the load between a number of machines. In this paper we introduce a method of partitioning agents onto machines using an adapted k-means clustering algorithm. We present, validate and use an analysis tool to compare the proposed clustered partitioning approach with a series of existing methods.","Title: Toward an Evolutionary Computing Modeling Language\nYear: 2011\n\nAbstract: The importance of domain knowledge in the design of effective evolutionary algorithms (EAs) is widely acknowledged in the meta-heuristics community. In the last few decades, a plethora of EAs has been manually designed by domain experts for solving domain-specific problems. Specialization has been achieved mainly by embedding available domain knowledge into the algorithms. Although programming libraries have been made available to construct EAs, a unifying framework for designing specialized EAs across different problem domains and branches of evolutionary computing does not exist yet. In this paper, we address this issue by introducing an evolutionary computing modeling language (ECML) which is based on the unified modeling language (UML). ECML incorporates basic UML elements and introduces new extensions that are specially needed for the evolutionary computation domain. Subsequently, the concept of meta evolutionary algorithms (MEAs) is introduced as a family of EAs that is capable of interpreting ECML. MEAs are solvers that are not restricted to a particular problem domain or branch of evolutionary computing through the use of ECML. By separating problem-specific domain knowledge from the EA implementation, we show that a unified framework for evolutionary computation can be attained. We demonstrate our approach by applying it to a number of examples.","Title: A scalable architecture for supporting interactive games on the internet\nYear: 2002\n\nAbstract: This paper presents a scalable architecture for supporting large-scale interactive Internet games. In order to support a large number of participants and to divide the workload, the virtual world is divided into partitions. Each partition is then assigned to a server. A client (i.e., a player or a participant) will join a server according to the position of the avatar it controls. Compared to a centralized architecture, this distributed client-server architecture is more scalable. In addition, compared to a fully distributed, peer-to-peer architecture, it also provides a means for detecting cheating in distributed games. Since interactions and accounting information must be forwarded directly to one of the servers for qualification and verification, cheating amongst distributed players of the game will be minimized. To support secured communication for interactions and accounting information as well as to speedup periodic update messages (e.g., position updates), a hybrid communication scheme using both TCP and IP multicast is used between clients and the associated server. The communication among servers is enabled by the Run-Time Infrastructure (RTI) services. The High Level Architecture (HLA) Data Distribution Management (DDM) is employed to limit the amount of communication between the servers. In addition, the Ownership Management (OM) is also employed to implement the need for transferring the avatars between servers. In this paper, the design detail of the architecture will be presented. An experimental interactive Internet game realized using the architecture will be also described in the paper.","Title: Grid Services and Service Discovery for HLA-Based Distributed Simulation\nYear: 2004\n\nAbstract: Modelling and simulation permeate all areas of business, science and engineering and increasingly complex simulation systems often require huge computing resources and data sets that are geographically distributed. The widely adopted platform for building distributed simulations is the High Level Architecture (HLA). Deficiencies associated with HLA have been well discussed in the literature. The advent of Grid technology enables the use of distributed computing resources and facilitates the access of geographically distributed data. In this paper, we propose a framework for executing large-scale distributed simulations using Grid services. The framework addresses some of the deficiencies of HLA, including dynamic discovery and resource utilization. End-users can construct large-scale distributed simulations using this framework with ease.","Title: Dynamic specialization for symbiotic simulation-based operational decision support using the evolutionary computing modelling language (ECML).\nYear: 2014\n\nAbstract: Simulation-based what-if analysis is an important tool that can be used to support operational decision making. Solutions to operational decision problems have to be found in a limited period of time. As a result of these time constraints, not all candidate solutions can be evaluated by means of simulation. Essentially, this problem solving process is an optimization process. Specialization of the optimization method can help to reduce the computing budget needed to find an appropriate solution. However, since operational conditions are constantly changing, the exact problem is not known at design time. Therefore, the optimization method has to be specialized during runtime. This can be done by dynamically incorporating situation-dependent problem-specific knowledge into the optimization process. We introduce a method based on an evolutionary algorithm, which supports dynamic specialization. Furthermore, we demonstrate the effectiveness of this method in the context of a semiconductor manufacturing application.","Title: Enhancement of Collaborative Interest Management Mechanism for P2P Networked Virtual Environment\nYear: 2012\n\nAbstract: Interest Management (IM) aims at eliminating irrelevant state updates transmitted in Networked Virtual Environment (NVE), such as online games. The existing IM mechanisms include area-based, cell-based mechanisms and hybrid IM mechanism which reduces the communication overhead by utilizing the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism. Comparing to the existing IM mechanisms, the recently proposed collaborative IM mechanism (CIM) successfully reduces the communication cost further. However, two problems exist in the current CIM mechanism: i) the protocol may fail under certain circumstances, and ii) the protocol requires dividing the virtual environment into fixed grids. In this paper, we focus on the approaches that could enhance the current CIM mechanism and we will evaluate the performance using simulation of multiplayer game scenarios.","Title: Adaptive Policing for Token-Exchange Based Management of Shared Computing Resources\nYear: 2006\n\nAbstract: Resource contention on shared resources occurs when workload demands exceed the aggregate capacity of shared resources in the community. The token-exchange incentive scheme is traditionally employed to motivate organizations to contribute sufficiently to the community, as a means to minimize free riding. The same incentive scheme can concurrently be used to serve as a mechanism for performing admission control on jobs submitted by users. However, due to the likelihood of fluctuations in demand for computing resources, the initial assignment of tokens on the basis of each organization's resource contribution, may have a significant impact on the performance trade-off between fairness and the system admission ratio. To address this problem, we extend the token-exchange scheme by designing trading policies that are responsive to the instantaneous degree of contention, so that, the trade-off between fairness and the admission ratio is less sensitive to the actual quantity of tokens assigned to each organization.","Title: Hierarchical federations: an architecture for information hiding\nYear: 2001\n\nAbstract: In a distributed simulation, simulation components of various types are executed at geographically different locations, forming a simulation federation to create a common virtual environment. Under the High Level Architecture (HLA), information that will be produced and consumed by a simulation component is defined in its object model, and how that information is produced and consumed is well encapsulated inside the simulation component's implementation. However in the current implementation of the HLA's Runtime Infrastructure (RTI), information hiding between groups of simulation components in a simulation federation is not addressed. The authors discuss how hierarchical federation architectures can be used to tackle this problem. The hierarchical federation architecture adopted in the paper differs from the existing architectures in that it is based on a hybrid approach for interoperability between simulation federations. To demonstrate information hiding using the architecture, a distributed semiconductor supply-chain simulation is also described","Title: JBSP: a BSP programming library in Java\nYear: 2001\n\nAbstract: In this paper, we introduce a Java implementation of the Bulk Synchronous Parallel(BSP) model. JBSP (a Java-based BSP system) uses a two-daemon architecturewhich makes a clear separation of the computation and communication involvedin parallel programs. Java threads are used in the implementation of the JBSPsystem to realize user dened JBSP tasks as well as to carry out system activities.","Title: Implementation Lessons of Performance Prediction Tool for Parallel Conservative Simulation (Research Note)\nYear: 2000\n\nAbstract: Performance prediction is useful in helping parallel programmers answer questions such as speedup scalability. Performance prediction for parallel simulation requires first working out the performance analyzer algorithms for specific simulation protocols. In order for the prediction results to be close to the results from actual parallel executions, there are further considerations when implementing the analyzer. These include (a) equivalence of code between the sequential program and parallel program, and (b) system effects (e.g. cache miss rates and synchronization overheads in an actual parallel execution). This paper describes our investigations into these issues on a performance analyzer for a conservative, \"super-step\" (synchronous) simulation protocol.","Title: Workload management of cooperatively federated computing clusters\nYear: 2006\n\nAbstract: Cooperative resource sharing enables distinct organizations to form a federation of computing resources. The motivation behind cooperation is that organizations are likely to serve each other by trading unused CPU cycles given the existence of irregular usage patterns of their local resources. In this way, resource sharing would enable organizations to purchase resources at a feasible level while meeting peak computational throughput requirements. This federation results in community grid that must be managed. A functional broker is deployed to facilitate remote resource access within the community grid. A major issue is the problem of correlations in job arrivals caused by seasonal usage and/or coincident resource usage demand patterns. These correlations incur high levels of burstiness in job arrivals causing the job queue of the broker to grow to an extent such that its performance becomes severely impaired. Since job arrivals cannot be controlled, management strategies must be employed to admit jobs in a manner that can sustain a fair level of resource allocation performance at all participating organizations in the community. In this paper, we present a theoretical analysis of the problem of job traffic burstiness on resource allocation performance in order to elicit the general job management strategies to be employed. Based on the analysis, we define and justify a job management strategies for the resource broker to cope with overload conditions caused by job arrival correlations.","Title: A Framework for Robust HLA-based Distributed Simulations\nYear: 2006\n\nAbstract: The High Level Architecture (HLA) is a standard for the interoperability and reuse of simulation components, referred to as federates. Large scale HLA-compliant simulations are built to study complex problems, and they often involve a large number of federates and vast computing resources. Simulation federates running at different locations are liable to failure. The failure of one federate can lead to the crash of the overall simulation execution. Such risk increases with the scale of a distributed simulation. Hence, fault-tolerance is required to support runtime robustness. This paper introduces a framework for robust HLAbased distributed simulations using a \"Decoupled Federate Architecture. Our framework exploits the architecture to provide a generic fault-tolerant model, that exploits a \"dynamic substitution approach to deal with failure. A sender-based method is designed to ensure reliable in-transit message delivery, which is coupled with a novel algorithm to perform effective fossil collection. The fault-tolerant model also avoids any unnecessary repeated computation when handling failure. The framework supports reusability of legacy federate code, and it is platform-neutral and independent of federate modeling approaches. Experiments have been carried out to validate and benchmark the fault-tolerant federates using an example of a simple supply-chain simulation. The experimental results show that the framework provides correct failure recovery and indicate that the overhead for facilitating fault-tolerance is minimal.","Title: Large Scale Distributed Simulation on the Grid\nYear: 2006\n\nAbstract: The developmentof many complex siumulation applications requires collaborrrtive effortfrom reseachers with different domain knowledge and expertise,possibly at different locations. These simulations systems often require huge computing resources and data set, which may be geo- graphically distribyted,In ordr to support collaborative model development and to cater for the increasing comoplex- ity of such systems, it is necessary to harness distributed resources over the Internet.the emergence of Grid tech nologies provide exciting new opportunities for large scale distributed simulation, enabling collaboration and the use of distributed computing resources, while also facilitating access to geographically distributed data sets. This paperdiscusses the research challenges that must be addressesbefore these opportunities can be exploited and presents HLA-GRID_REPast, a system for executing large scale distributed simulations of agent based systems over the Grid.","Title: A Framework for Performance Evaluation of Large-scale Interactive Distributed Virtual Environments\nYear: 2010\n\nAbstract: Interactivity is a key consideration in large-scale distributed virtual environments (DVEs), such as massively multi-player online games. Due to the Internet dynamics as well as the large-scale and distributed nature of many DVEs, it is difficult to quantify the possible improvements claimed by various DVE interactivity enhancement approaches. In this paper, we propose a scalable framework that supports evaluation of interactivity indicators, under dynamic Internet conditions. We have developed and used this framework to conduct extensive experiments on PlanetLab with many distributed client and server locations. We have collected the latency experienced by over 700 client locations distributed around the globe over a few days; and used it for evaluating performance of some recently proposed zone mapping algorithms.","Title: A framework of evaluating partitioning mechanisms for agent-based simulation systems\nYear: 2009\n\nAbstract: For an agent-based system that aims to simulate a large number of agents under different scenarios, a proper partitioning mechanism is an essential factor to the performance of the system. However, there is still an issue on selecting/developing an appropriate partitioning mechanism for a specific agent-based simulation system. One way is to implement distributed agent-based systems using multiple partitioning mechanisms and to compare their performance. However this is in general not feasible. In this paper, we propose a generic framework and a simple evaluation process to address the issue of selecting an appreciate partitioning mechanism by simulating the effect of the partitioning mechanism to predict its performance for an agent-based simulation system.","Title: Critical causal order of events in distributed virtual environments\nYear: 2007\n\nAbstract: We investigate the causal order of events in distributed virtual environments (DVEs). We first define the critical causal order relation among the events. Then, we propose some mechanisms to enhance the prevalent RO (receive order delivery) mechanism in DVEs so that the real-time property of DVEs is preserved while the critical causal order violations are reduced. These mechanisms are implemented as a middleware. Experimental results show that the middleware performs well in reducing the critical causality violations in simulation and incurs little processing overhead.","Title: Multi-user Gaming on the Grid Using a Service Oriented HLA RTI\nYear: 2009\n\nAbstract: Interactive multi-user Internet games require frequent state updates between players to accommodate the great demand for reality and interactivity. The large latency and limited bandwidth on the Internet greatly affects the game’s scalability. The High Level Architecture (HLA) is the IEEE standard for distributed simulation with its Data Distribution Management (DDM) service group assuming the functionalities of interest management. With its support for reuse and interoperability and its DDM support for communication optimization, the HLA is promising at supporting multi-user gaming on the Internet. However, this usually requires particular prior security setup across administrative domains according to the specific Run Time Infrastructure (RTI) used. We have previously developed a Service Oriented HLA RTI (SOHR) which enables distributed simulations to be conducted across administrated domains on the Grid. This paper discusses multi-user gaming on the Grid using SOHR. Specifically, a maze game is used to illustrate how SOHR enables users to join a game conveniently. Experiments have been carried out to show how DDM can improve the communication efficiency.","Title: Time management in a service-oriented architecture for distributed simulation on the grid\nYear: 2007\n\nAbstract: A Service-Oriented Architecture is essentially a collection of independent services with well-defined interfaces that can be accessed without knowledge of their implementation. The architecture is widely used in Grid computing to achieve resource virtualization, on-demand provisioning, and service (resource) sharing. As the Grid has shown its potential as a suitable environment for simulation and modeling, a Service-Oriented Architecture for Distributed Simulation on the Grid (SOAr-DSGrid) was proposed. Like other simulation systems, time management is a crucial part of the whole system. It manages the logical time and guarantees that the whole simulation system is causally correct. This paper describes the implementation of distributed time management in SOAr-DSGrid. The time management makes use of the simulation topology information to reduce constraints on time advancement between simulation components. Various experiments conducted on a cluster demonstrate that a fully distributed time management system has better scalability and efficiency than the centralized version.","Title: Parallel discrete event simulation of manufacturing systems using parsec\nYear: 2000\n\nAbstract: Most existing Parallel Discrete Event Simulation (PDES) languages are general-purpose simulation languages, which are useful for constructing general simulation applications. However, they lack features to support special models, such as those in manufacturing simulation. In a study of a wafer fabrication simulation, one feature that complicates the implementation using a general-purpose PDES language is the specification of dispatching and setup rules. This paper studies the performance of different implementation alternatives of a wafer fabrication simulation using an existing general-purpose PDES language. In our study, the wafer fabrication simulation model is based on the Sematech Data Modeling Standard, and PARSEC is selected as the general-purpose PDES language.","Title: Modeling Human-Like Decision Making for Virtual Agents in Time-Critical Situations\nYear: 2010\n\nAbstract: Generating human-like behaviors for virtual agents has become increasingly important in many applications, such as crowd simulation, virtual training, digital entertainment, and safety planning. One of challenging issues in behavior modeling is how virtual agents make decisions given some time-critical and uncertain situations. In this paper, we present HumDPM, a decision process model for virtual agents, which incorporates two important factors of human decision making in time-critical situations: experience and emotion. In HumDPM, rather than relying on deliberate rational analysis, an agent makes its decisions by matching past experience cases to the current situation. We propose the detailed representation of experience case and investigate the mechanisms of situation assessment, experience matching and experience execution. To incorporate emotion into HumDPM, we introduce an emotion appraisal process in situation assessment for emotion elicitation. In HumDPM, the decision making process of an agent may be affected by its emotional states when: 1) deciding whether it is necessary to do a re-match of experience cases, 2) determining the situational context, and 3) selecting experience cases. We illustrate the effectiveness of HumDPM in crowd simulation. A case study for emergency evacuation in a subway station scenario is conducted, which shows how a varied crowd composition leads to different evacuation behaviors, due to the retrieval of different experiences and the variation of agents' emotional states.","Title: A Data-Driven Crowd Simulation Model Based on Clustering and Classification\nYear: 2013\n\nAbstract: In this paper, we propose a data-driven crowd behavior model that is constructed by extracting examples from human motion data describing how humans make decisions. We cluster the examples before the simulation to find similar patterns of behavior. During the simulation, at each simulation time step, we first classify the input state perceived by an agent in the simulation into one example cluster using an artificial neural network classifier. We then combine similar examples of that cluster to produce an output, a velocity vector indicating the position of the agent in the next time step. Such a two step matching process enables the selection of the most similar example accurately and efficiently. To verify our approach, we have developed an initial prototype in which we build our model using motion data generated by a RVO2 simulator, attempting to reproduce the behavior of the RVO2 model. By comparing the position of the same agent simulated by the RVO2 mode land our model respectively at the same time steps, we show that our model has the ability to reproduce the behavior of the RVO2 model accurately. As future work, we will use real human motion data as model input, so that our model may perform human-like motion behavior.","Title: Execution coordination in mobile agent-based distributed job workflow execution\nYear: 2008\n\nAbstract: Mobile agent-based distributed job workflow execution requires the use of execution coordination techniques to ensure that an agent executing a subjob can locate its predecessors' execution results. This paper describes the classification, implementation, and evaluation of execution coordination techniques in the mobile agent-based distributed job workflow execution system. First, a classification of the existing execution coordination techniques is developed for mobile agent systems. Second, to put the discussion into perspective, our framework for mobile agent-based distributed job workflow execution over the Grid (that is, MCCF: Mobile Code Collaboration Framework) is described. How the existing coordination techniques can be applied in the MCCF is also discussed. Finally, a performance study has been conducted to evaluate three coordination techniques using real and simulated job workflows. The results are presented and discussed in the paper.","Title: Synchronization in federation community networks\nYear: 2010\n\nAbstract: A large scale High Level Architecture (HLA)-based simulation can be constructed using a network of simulation federations to form a ''federation community''. This effort is often for the sake of enhancing scalability, interoperability, composability and enabling information security. Synchronization mechanisms are essential to coordinate the execution of federates and event transmissions across the boundaries of interlinked federations. We have developed a generic synchronization mechanism for federation community networks with its correctness mathematically proved. The synchronization mechanism suits various types of federation community network and supports the reusability of legacy federates. It is platform-neutral and independent of federate modeling approaches. The synchronization mechanism has been evaluated in the context of the Grid-enabled federation community approach, which allows simulation users to benefit from both Grid computing technologies and the federation community approach. A series of experiments has been carried out to validate and benchmark the synchronization mechanism. The experimental results indicate that the proposed mechanism provides correct time management services to federation communities. The results also show that the mechanism exhibits encouraging performance in terms of synchronization efficiency and scalability.","Title: Dynamic load-balancing in a data parallel object-oriented system\nYear: 2001\n\nAbstract: In this paper, a parallel object collection (POC) model is introduced to support data parallelism in a parallel object-oriented system. This model is based on the idea of data partitioning and method replication. To achieve load-balancing, partition objects are dynamically migrated at runtime according to the system load situation. A threshold-based strategy is used in the dynamic load-balancing. To avoid over-convergence of load during partition object migration, a new destination node selection algorithm is proposed. The threshold values used in the algorithm are also adaptively adjusted to better reflect the fluctuation of the load during execution. To evaluate the performance of the dynamic load balancing algorithm, simulation experiments are conducted. The simulation results are reported and discussed in the paper.","Title: Preventive what-if analysis in symbiotic simulation\nYear: 2008\n\nAbstract: The what-if analysis process is essential in symbiotic simulation systems. It is responsible for creating a number of alternative what-if scenarios and evaluating their performance by means of simulation. Most applications use a reactive approach for triggering the what-if analysis process. In this paper we describe a preventive triggering approach which is based on the detection of a future critical condition in the forecast of a physical system. With decreasing probability of a critical condition, using preventive what-if analysis becomes undesirable. We introduce the notion of a G-value and explain how this metric can be used to decide whether or not to use preventive what-if analysis. In addition, we give an example for a possible application in semiconductor manufacturing.","Title: Flexible State Update Mechanism for Large-Scale Distributed Wargame Simulations\nYear: 2007\n\nAbstract: Large-scale wargame simulations may involve tens of thousands of entities and generally run on distributed simulation nodes. An important issue in constructing these applications is to reduce the amount of data transmitted among the distributed simulation nodes so that the network and the simulation nodes will not be flooded by the state update messages. To this end, we first propose a timeliness condition on how frequently the state updates of a local simulation entity need to be sent to other remote simulation nodes. A fleXible state update mechanism is then proposed to ensure the update intervals of the entities meet the required timeliness update condition and, in the meantime, balance the number of entities that need to be updated in each simulation time step (referred to here as the frame). EXperiments with a distributed wargame simulation indicate that the proposed mechanism can significantly reduce the number of messages sent over the network while still maintaining the simulation fidelity.","Title: Provenance Provisioning in Mobile Agent-Based Distributed Job Workflow Execution\nYear: 2007\n\nAbstract: Job workflow systems automate the execution of scientific applications, however they may hide how the results are achieved (i.e., the provenance information of the job workflow execution). This paper describes the development and evaluation of a decentralized recording and collection scheme for job workflow provenance in mobile agent-based distributed job workflow execution. A performance study was conducted to evaluate our approach against the one using a centralized provenance server. The results are discussed in the paper.","Title: A Computational Model of Emotions for Agent-Based Crowds in Serious Games\nYear: 2011\n\nAbstract: Crowd behaviour is an interesting social phenomenon that emerges from complex interactions of individuals. An important aspect of individual behaviour is emotion which plays a significant role in all aspects of human decision making. For example, heightened emotional states can lead people to take highly unexpected or irrational actions. One popular motivation for simulation of virtual crowds is to generate believable characters in movies and computer games. Recently the concept of serious games has been introduced in both academic and industrial circles. In this paper, we propose an emotion engine, based on modern appraisal theory, that is able to model various emotional crowd characteristics. This appraisal engine is capable of capturing the dynamics of emotional contagion and we show how different crowd composition can lead to different patterns of emotional contagion. In addition, we describe a serious game designed for training military personnel in peaceful crowd control. We evaluate this engine in the context of a property protection protest scenario where the players or soldiers are tasked to maintain a peaceful protest without violence. A systematic evaluation is presented which supports the facial validity of the emotion engine and our model of emotional contagion.","Title: A decoupled federate architecture for high level architecture-based distributed simulation\nYear: 2008\n\nAbstract: A number of research issues arise in executing large scale High Level Architecture (HLA) based distributed simulations. Among these issues distributed simulation cloning, fault tolerance and Grid enabled architecture are particularly important and challenging. This paper presents a Decoupled Federate Architecture as the underlying infrastructure to facilitate a solution to each of the above issues. Distributed simulation cloning has been designed to improve the performance of ''what-if'' analysis, by enabling the examination of alternative scenarios concurrently within the same execution session. Furthermore, simulation federates running at different locations are liable to failure. Such risk increases with the scale of a distributed simulation. The architecture has also been exploited to form the basis of a generic framework to support runtime robustness. The development of complex simulation applications often requires geographically distributed huge computing resources and data sets. Using the architecture, Web and Grid technologies have been successfully combined with existing simulation technologies thus to enhance interoperability and execution flexibility for such simulations. Benchmark experiments have been performed to study the extra overhead incurred by the Decoupled Federate Architecture against a normal federate. Encouraging experimental results indicate that a well designed architecture can achieve performance close to the normal one in terms of latency and time synchronization. Additional experiments have been presented for evaluating the three solutions supported by the architecture.","Title: Graphical views of the behavior of parallel programs\nYear: 1993\n\nAbstract: There is often an increasing gap between a programmer′s mental conception of a problem and the realization of a parallel program which solves that problem. To bridge this gap, information about program execution must be displayed. Since a parallel program may be executed on several processors simultaneously, activities may be distributed across both space and time, and therefore simple sequential displays of a program′s execution are inadequate. Intuitively, pictures are much more meaningful than text, particularly with parallel programs where large quantities of information may be generated. In this paper, we describe how the behavior of parallel programs may be graphically interpreted, and discuss current approaches and difficulties in parallel program visualization. A graphical interface designed for languages based on message-passing is also presented.","Title: A Simulation Study of Dynamic Load Balancing for Network-based Parallel Processing\nYear: 1997\n\nAbstract: A simulation study of dynamic load balancing for parallel processing on Network Of Workstations (NOW) is presented in this paper. A simulation model is constructed. It includes a representative CPU scheduling policy, and also considers the message exchange, task transfer and migration costs explicitly. A global dynamic load balancing algorithm is simulated. Both task transfer and task migration are considered. The performance of the algorithm under both homogeneous and heterogeneous environments is analyzed. In addition, the interaction of parallel and sequential workloads on an NOW is also examined. Our results show that dynamic load balancing can achieve better performance improvement for heterogeneous systems than for homogeneous systems; it is especially effective in a system where both parallel and sequential tasks concurrently exist; and the use of task migration generally does not further improve performance.","Title: Application Layer Multicast in P2P Distributed Interactive Applications\nYear: 2013\n\nAbstract: By sharing resources among peers in peer-to-peer network, application layer multicast (ALM) has been shown an efficient way to improve the scalability and reduce the latency of communication. To deploy ALM in peer-to-peer distributed interactive applications (DIAs), the property of many-to-many communication of DIA demands multiple multicast trees to be constructed in the overlay. Therefore, how to efficiently allocate resources among multiple trees to maximize the benefit is an important and challenging issue. In this paper, we study the problem of building ALM trees with minimum total end-to-end delay to receivers in peer-to-peer DIAs with resource constraints on network bandwidth. The end-to-end delay from a sender to receivers in a multicast tree consists of the link delay as well as the packet queuing delay at intermediate peers, while the latter is often ignored or not well studied in the previous work. In this paper, we explicitly establish the relationship between the queuing delay at peers and the topology of multicast trees in peer-to-peer DIAs. Based on the relationship, the above mentioned problem is defined and we prove that it is NP-complete. We present a centralized heuristic algorithm to obtain an approximate solution. Moreover, distributed algorithms are also investigated to refine the topology in practical systems with dynamic changes. Extensive experiments were conducted by simulations to evaluate the proposed algorithms and results are reported in the paper.","Title: Towards Fault-tolerant HLA-based Distributed Simulations\nYear: 2008\n\nAbstract: Large scale High Level Architecture (HLA)-based simulations are built to study complex problems, and they often involve a large number of federates and vast computing resources. Simulation federates running at different locations are subject to failure. The failure of one federate can lead to the crash of the overall simulation execution. Such risk increases with the scale of a distributed simulation. Hence, fault tolerance is required to support runtime robustness. This paper introduces a framework for robust HLA-based distributed simulations using a 'Decoupled Federate Architecture'. The framework provides a generic fault-tolerant model, which deals with failure with a dynamic substitution approach. A sender-based method is designed to ensure reliable in-transit message delivery, which is coupled with a novel algorithm to perform effective fossil collection. The fault-tolerant model also avoids any unnecessary repeated computation when handling failure. Using a middleware approach, the framework supports reusability of legacy federate code and it is platform-neutral and independent of federate modeling approaches. Experiments have been carried out to validate and benchmark the fault-tolerant federates using an example of a supply-chain simulation. The experimental results show that the framework provides correct failure recovery. The results also indicate that the framework only incurs minimal overhead for facilitating fault tolerance and has a promising scalability.","Title: DPBP: a sort-first parallel rendering algorithm for distributed rendering environments\nYear: 2003\n\nAbstract: In some visualization systems, the data and computational resources are distributed globally and users need to interact with these resources easily and efficiently. Real-time rendering for massive datasets is a computation intensive task. one solution is to distributes the rendering tasks over a set of computation units to achieve high rendering performance. This paper presents a recursive sort-first partitioning algorithm named Dynamic Pixel Bucket Partition (DPBP) for parallel rendering alone with their implementation and performance in a distributed rendering environment. This algorithm distributes rendering work loads evenly to individual rendering units to achieve fast, high quality rendering of massive data. Test results in a multi-cluster environment demonstrate the practicality of this rendering algorithm.","Title: Managing event traces for a web front-end to a parallel simulation\nYear: 2001\n\nAbstract: To enhance the widespread use of a parallel supply chain simulator, a web front-end that enables access at any time and from any location has been developed. The front-end provides the capability of model uploading, simulation runs initiation, simulation activities visualization, and simulation statistics collection. Visualizing the simulation activities requires the parallel simulator to record event traces to the file system for displaying purposes. To minimize the negative impact of the recording on the performance of parallel simulation, an event trace management algorithm, coupled with a buffering mechanism, is proposed. The approach was evaluated using six sample supply chain models. The results show that the proposed algorithm is capable of maintaining the same level of speedup when recording is performed (in the range of 2.5 to 3.0 on a 4-CPU shared memory system), as compared to runs without recording of event traces","Title: Network-Aware Server Placement for Highly Interactive Distributed Virtual Environments\nYear: 2008\n\nAbstract: In distributed virtual environments, e.g., online gaming, collaborative designs and distributed military simulations, interactivity is one of the most important requirements. The users may notice serious degradations in quality of service when interacting in the virtual world if the response from the system is much slower than what they have experienced in real life. In this paper, we consider the problem of placing distributed servers in the network to reduce client-server communication latencies, which is termed the server placement problem. We proposed two new network-aware placement algorithms which take into account users' locations in the network and connectivity at the Autonomous System level to determine good sites for servers. Extensive experiments with realistic network models showed that these new algorithms significantly outperform existing approaches that require full knowledge of network connectivity at the router-level topologies.","Title: A Distributed Rendering Environment for Massive Data on Computational Grids\nYear: 2003\n\nAbstract: Scientific visualization, especially for massive data sets, has emerged in different disciplines recently. Generally, distributed scientific visualization applications require multiple resources, e.g., high-end computing resources to process data, high speed network for data transfer and large size database for data storage. Furthermore, these applications will meet research challenges, e.g., heterogeneous resources, geographically distributed environment and considerable communication delay. This paper studies an application of distributed massive data rendering. We present infrastructure of the distributed rendering environment and explain how Grid technologies are used in this application. Dynamic Pixel Bucket Partition (DPBP) algorithm is a new algorithm proposed for task allocation of distributed rendering application in computational Grids. Experiments in real test ted shows the performance of DPBP algorithm and the framework.","Title: Autonomous Bee Colony Optimization for multi-objective function\nYear: 2010\n\nAbstract: An Autonomous Bee Colony Optimization (A-BCO) algorithm for solving multi-objective numerical problems is proposed. In contrast with previous Bee Colony algorithms, A-BCO utilizes a diversity-based performance metric to dynamically assess the archive set. This assessment is employed to adapt the bee colony structures and flying patterns. This self-adaptation feature is introduced to optimize the balance between exploration and exploitation during the search process. Moreover, the total number of search iterations is also determined/optimized by A-BCO, according to user pre-specified conditions, during the search process. We evaluate A-BCO upon numerical benchmark problems and the experimental results demonstrate the effectiveness and robustness of the proposed algorithm when compared with the Non-dominated Sorting Genetic Algorithm II and the latest Multi-objective Bee Colony Algorithm proposed to date.","Title: Alternative Solutions for Distributed Simulation Cloning.\nYear: 2003\n\nAbstract: Simulation cloning is designed to satisfy the requirement of examining alternative scenarios concurrently. This article discusses the issues involved in cloning distributed simulations based on the High Level Architecture (HLA) and proposes tentative solutions. Alternative solutions are compared from both the qualitative and quantitative point of view. In terms of federation organization, candidate solutions can be classified into the single-federation and the multiple-federation categories. To guarantee the correctness and optimize the performance of the whole cloning-enabled distributed simulation, the single-federation solution requires an additional mechanism to isolate the interactions among alternative executions. Data distribution management (DDM) is one of the candidate approaches. To measure the trade-off between complexity and efficiency, the authors introduce a series of experiments to benchmark various solutions at the runtime infrastructure (RTI) level. The benchmark results indicate that the single-federation solution provides encouraging performance when using DDM.","Title: Key Message Algorithm: A Communication Optimization Algorithm in Cluster-Based Parallel Computing\nYear: 1999\n\nAbstract: Parallel computing using Network of Workstations (NOWs) has become very popular recently. However, the execution of parallel applications on such systems has been hampered by the high communication overhead. To reduce the communication overhead and to speedup the execution of parallel applications on NOWs, this paper proposes a Key Message approach that minimizes the cost of message-passing in a parallel application by prioritizing communications in the underlying shared communication network. In this paper, we first describe the queuing network model on which our approach is based, then introduce the algorithm that identifies the messages to be prioritized in a parallel application, and finally discuss the results obtained. Our preliminary analysis of the algorithm on randomly generated task graphs shows improvement over the system without using the prioritization scheme.","Title: Fair and Efficient Dead Reckoning-Based Update Dissemination for Distributed Virtual Environments\nYear: 2012\n\nAbstract: Due to diverse network latencies, participants in a Distributed Virtual Environment (DVE) may observe different inconsistency levels of the simulated virtual world, which can seriously affect fair competition among them. In this paper, we investigate how to disseminate Dead Reckoning (DR)-based updates with the objectives of achieving fairness among participants and reducing inconsistency as much as possible. We first propose an optimized bandwidth allocation scheme for sending updates to overcome the drawbacks of uniform bandwidth allocation and the local-lag technique. Then, we integrate bandwidth allocation with an indirect relay method and develop algorithms to select relay routes for minimizing inconsistency under various bandwidth allocation schemes. Our proposed scheme and algorithms are evaluated using traces collected from a real car racing game as well as the real Internet latency data. The experimental results show that the proposed optimized bandwidth allocation scheme significantly reduces inconsistency while maintaining fairness among participants and that integrating the optimized scheme with our proposed relay setup algorithm further improves consistency.","Title: A hybrid Interest Management mechanism for peer-to-peer Networked Virtual Environments\nYear: 2010\n\nAbstract: An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Networked Virtual Environments (NVE). However, IM itself involves both computation and communication overhead, of which the latter is the focus of this paper. Traditionally, there are area-based and cell-based IM mechanisms. This paper proposes a hybrid IM mechanism for peer-to-peer NVEs, that utilizes the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism so as to reduce its communication overhead. To compare the new mechanism with the two traditional approaches, a multiplayer game scenario is simulated. The performance results show that, compared to the traditional mechanisms, the hybrid mechanism reduces the upload bandwidth consumption by more than 25.28 percent, reduces the overhead ratio from more than 67.54 percent to only 25.17 percent, and allows more than 5000 players in the Internet to join the same game with today's network upload bandwidth.","Title: Benchmarking IBM SP1 system for SPMD programming\nYear: 1996\n\nAbstract: The IBM SP1 is the first member of the IBM Scalable POWERparallel series, a distributed memory parallel computer based on RISC System/6000 processing element. In this paper, the benchmarking exercise of two message passing libraries, MPL and PVM, on the IBM SP1 for SPMD programming is described. We will discuss the benchmarks used in our experiment, and present the results we obtained. Our results indicate that to achieve performance improvement and to reduce the communication overhead, the use of the high performance switch is essential on the IBM SP1 machine","Title: Spatial indexing in agent-based crowd simulation\nYear: 2013\n\nAbstract: Crowd modeling and simulation has become a critical tool for understanding crowds and predicting their behaviours. This is accomplished by modelling the characteristics and behaviours of large groups of people, as well as their interactions. Agent-based crowd simulation may involve thousands of complex agents interacting in sophisticated ways, in close spatial proximity, with each other. A key challenge to the development of agent-based crowd simulation is the inherent complexity that is required to model all its necessary elements. A necessary feature of such a simulation is spatial indexing. This refers to the use of data structures to organize collections of simulation entities (e.g., agents and obstacles) in a manner which allows for efficient spatial querying. This is especially pertinent for large-scale crowd simulation with agents that sense their surrounding environment periodically, as the cost of spatial querying becomes computationally expensive if done naively. In this paper, we will describe our experience in improving the existing grid-based spatial indexing approach in our agent-based crowd simulation. Also, we will explore the integration of the adaptive spatial indices (e.g., R-tree and quad-tree) into our system. The performances of various spatial indexing techniques are examined in terms of efficiency and scalability.","Title: Parallel distributed simulation and modeling methods: causal order based time warp: a tradeoff of optimism\nYear: 2003\n\nAbstract: The optimistic synchronization paradigm, Time Warp, allows logical processes to advance aggressively. In the circumstances where the violation of the local causality constraint (LCC) is prone to occurring, this optimism may introduce substantial rollbacks and, as a consequence, significant overhead in recovering from erroneous computations. In this paper, a new approach, COBTW, is proposed, where the happen before relation is employed to capture the potential violations of LCC and causal order is applied to regulate the advancement of logical processes. Due to the difference between causal order and time-stamp order, there are discrepancies between them. Solutions to remove the discrepancies are proposed. Experiments conducted in a cluster and an emulated WAN suggest that COBTW reduces rollbacks caused by violations of LCC and empirically results in better performance, in comparison with the Time Warp protocol.","Title: Performance Evaluation of a Bandwidth Requirements Reduction Technique Based on Timely State Update\nYear: 2005\n\nAbstract: An important issue in distributed real-time simulation is to reduce the amount of data transmitted amongst distributed simulation nodes so that the state updates of simulation entities can be sent to other simulation nodes in a timely manner. To address this issue, we have previously proposed a consistency model to determine the update interval of entities based on their relative importance, a utility model to compute the relative importance of entities, and a flexible state update mechanism to ensure updating within these intervals and to balance the number of updates in each simulation frame. In this paper, we focus on the performance evaluation of these timely state update mechanisms. Using a battlefield benchmark, the performance is evaluated in terms of the total amount of data exchanged, the number of simulation frames skipped, and the number ofGo-Through-Accidents occurring during the simulation. The performance results indicate that the mechanisms can significantly reduce the bandwidth requirements while maintaining or even improving the consistency of the simulation.","Title: Consistency Aware Dead Reckoning Threshold Tuning with Server Assistance in Client-Server-Based DVEs\nYear: 2010\n\nAbstract: In distributed virtual environments (DVEs), maintaining a consistent view of the virtual world among all users is a primary task. Due to the resource limitations such as network capacity and computational power, the consistency of the virtual world cannot be guaranteed sometimes. In this paper, we try to address this problem in client-server-based DVEs by considering server side network capacity limitation. We look at the position update packets from client to server and show the impact of packet loss due to server side network capacity limitation on the consistency of the virtual world. We assume clients use Dead Reckoning (DR) models to control position updates. In order to adapt client updates with the server side network capacity to avoid update packet loss, two server assistant DR threshold tuning policies for different updating schemas are proposed in this paper. The proposed tuning polices are validated to have good performance by simulation results.","Title: Load balancing for conservative simulation on shared memory multiprocessor systems\nYear: 2000\n\nAbstract: Load balancing is a crucial factor in achieving good performance for parallel discrete event simulations. We present a load balancing scheme that combines both static partitioning and dynamic load balancing. The static partitioning scheme maps simulation objects to logical processes before simulation starts while the dynamic load balancing scheme attempts to balance the load during runtime. The static scheme involves two steps. First, the simulation objects that contribute to small lookahead are merged together by using a merging algorithm. Then a partitioning algorithm is applied. The merging is needed to ensure a consistent performance for our dynamic scheme. Our dynamic scheme is tailor-made for an asynchronous simulation protocol that does not rely on null messages. The performance study on a supply chain simulation shows that the partitioning algorithm and dynamic load balancing are important in achieving good performance","Title: Shared Variable Management in SOAr-DSGrid\nYear: 2008\n\nAbstract: Simulation is a low cost alternative to experimentation on real-world physical systems. In light of the prevalence of web services, issues relating to distributed simulation using web services have come to the fore in recent years. We have proposed a service-oriented architecture for distributed simulations on the Grid (SOAr-DSGrid). SOAr-DSGrid facilitates the development and execution of distributed simulations in different views (i.e., a component-based view for development and a service-oriented view for execution). At run time, one component may require information from another component for execution or decision-making. In SOAr-DSGrid, this shared information from one component to another component is implemented through shared variables. Since two components may execute out of phase, without proper shared variable management, the value provided by one component may be invalid for another component due to the time difference. Since SOAr-DSGrid provides a service-oriented view for component execution, the development of shared variable support also follows the service-oriented methodology. Three different approaches, namely Pull without FutureList, Pull with FutureList, and Push, have been implemented as the internal mechanism to solve the shared variable issue. Experimental results of the performance of these three approaches are also presented in this paper.","Title: A systematic approach for rapid 3D reconstruction from photosets.\nYear: 2010\n\nAbstract: We present an interactive framework for rapid 3D reconstruction of objects from sets of photographs. Our framework implements advanced 2D image-based modeling techniques that accurately compute geometries of digital photorealistic 3D models in a rapid and robust method. It is implemented in an application tool to assist users to perform feature detection, matching and meshing. Our system demonstrates that with a few user's intervention through our application tool, efficient generation of 3D object models can be generated from a set of photos.","Title: Servicing Provisioning for HLA-Based Distributed Simulation on the Grid\nYear: 2005\n\nAbstract: Modeling and simulation permeate all areas of business, science and engineering. With the increase in the scale and complexity of simulations, large amounts of computational resources are required, and provisioning of the services is becoming increasingly difficult. The Grid provides a platform for coordinated resource sharing and application development and execution. In this paper, we focus on extending the High Level Architecture (HLA) to the Grid. More specifically, we propose a distributed simulation framework, called HLAGrid. The framework uses a Federate-Proxy-RTI architecture, which allows resources on the Grid to be utilized on demand by using Grid services. The architecture also supports federation discovery, security of the simulator logic, and flexible federation construction, such as hierarchical federations. The architecture hides the heterogeneity of the simulators, simulatorsý execution platforms, and how the simulators communicate with the RTI. All interfaces used in the framework comply with the standard HLA interface specification, which provides reusability to simulators. A prototype of the framework is implemented using DMSOýs RTI 1.3NG version 6 and the Grid system runs the Globus Toolkit.","Title: Improving performance by replicating simulations with alternative synchronization approaches\nYear: 2008\n\nAbstract: Parallel and distributed simulation facilitates the construction of a simulation application (i.e., federation in HLA terminology) with a number of simulation components (federates). Recently, an approach based on active replication technique has been proposed to improve the performance of simulations by exploring software diversity. To guarantee the correctness of the approach, all replicas of the same federate are required to be Piece-Wise-Deterministic (PWD). However, the PWD restriction will not be satisfied if the replicas achieve software diversity by employing different kinds of synchronization approaches. A replication structure is proposed in this paper, which can transparently handle the federate replicas that use either conservative or optimistic synchronization approach. The execution speed of the federation is increased by always choosing the fastest replica to represent the federate in the federation. Besides presenting the implementation details, we also report the experimental results to demonstrate the performance improvement of the replication structure.","Title: A Parallelism Analyzer Algorithm for a Conservative Super-Step Simulation Protocol\nYear: 1999\n\nAbstract: Given an existing complex sequential simulation program, it is useful to have a parallelism analysis algorithm to quickly predict the corresponding parallel simulation program's performance. Wong et al. have described such an algorithm for the asynchronous Chandy-Misra-Bryant simulation protocol. This paper describes a parallelism analysis algorithm for a \"synchronous\\super-step\" protocol. We also discuss the assumptions needed in order for the prediction to be meaningful (i.e it should re ect at least one of the possible parallel runs), and the analyzer algorithm's correctness. Finally we will brie y discuss the algorithm modifications needed if we are to remove one of the assumptions.","Title: Dead Reckoning-Based Update Scheduling against Message Loss for Improving Consistency in DVEs\nYear: 2011\n\nAbstract: Maintaining a consistent presentation of the virtual world among participants is a fundamental problem in the Distributed Virtual Environment (DVE). The problem is exacerbated due to the limited network bandwidth and errorprone transmission. This paper investigates Dead Reckoning (DR) update scheduling to improve consistency in the DVE against message loss. Using the metric of Time-Space Inconsistency (TSI), which combines the spatial magnitude and temporal duration of inconsistency, we analytically derive the impact of message loss on TSI when using a DR-based update mechanism. To improve consistency against message loss, a naive update scheduling algorithm is first proposed, in which the expected spatial difference is calculated by taking message loss into account. In order to reduce the TSI to the case without transmission failures, a compensation update scheduling algorithm is further proposed by reducing the DR threshold according to the message loss rate. Using these algorithms, a budget-based mechanism is developed to meet the network bandwidth constraint. We show through experiments using a racing car game that the budget-based mechanism using the compensation update scheduling algorithm makes the best use of available network bandwidth to reduce the inconsistency and its impact on the participants. In addition, it ensures fairness among participants in spite of widely varying message loss rates.","Title: Time-space consistency in large-scale distributed virtual environments\nYear: 2004\n\nAbstract: Maintaining a consistent view of the simulated world among different simulation nodes is a fundamental problem in large-scale distributed virtual environments (DVEs). In this paper, we characterize this problem by quantifying the time-space inconsistency in a DVE. To this end, a metric is defined to measure the time-space inconsistency in a DVE. One major advantage of the metric is that it may be estimated based on some characteristic parameters of a DVE, such as clock asynchrony, message transmission delay, the accuracy of the dead reckoning algorithm, the kinetics of the moving entity, and human factors. Thus the metric can be used to evaluate the time-space consistency property of a DVE without the actual execution of the DVE application, which is especially useful in the design stage of a DVE. Our work also clearly shows how the characteristic parameters of a DVE are interrelated in deciding the time-space inconsistency, so that we may fine-tune the DVE to make it as consistent as possible. To verify the effectiveness of the metric, a Ping-Pong game is developed. Experimental results show that the metric is effective in evaluating the time-space consistency property of the game.","Title: Symbiotic Simulation Control in Semiconductor Manufacturing\nYear: 2008\n\nAbstract: Semiconductor manufacturing is a highly complex and asset intensive process. Solutions are needed to automate control of equipment and improve efficiency. We describe a symbiotic simulation control system which uses reactive what-if analysis to find a stable configuration of a wet bench tool set. This control system is based on a generic framework for symbiotic simulation. We show that symbiotic simulation can be used to make control decisions in near real-time. Furthermore, we show that our approach yields a notable performance improvement over common practise.","Title: Analysis of an efficient rule-based motion planning system for simulating human crowds\nYear: 2010\n\nAbstract: This paper proposes a rule-based motion planning system for agent-based crowd simulation, consisting of sets of rules for\n both collision avoidance and collision response. In order to avoid an oncoming collision, a set of rules for velocity sampling\n and evaluation is proposed, which aims to choose a velocity with an expected time to collision larger than a predefined threshold.\n In order to improve the efficiency over existing methods, the sampling procedure terminates upon finding an appropriate velocity.\n Moreover, the proposed motion planning system does not guarantee a collision-free movement. In case of collision, another\n set of rules is also defined to direct the agent to make a corresponding response. The experiment results show that the proposed\n approach can be applied in different scenarios, while making the simulation execution efficient.","Title: Dag consistent parallel simulation: a predictable and robust conservative algorithm\nYear: 1997\n\nAbstract: We present a novel approach to parallel discrete event simulation based on the Cilk model of multithreaded computation. Cilk's runtime system not only manages the low-level aspects of program execution, but also provides the user with an algorithmic model of performance which can be used to predict the execution time of a parallel simulation. Moreover, a Cilk application can ``scale down'' to run on a single processor with nearly the same performance as that of serial code.A conservative parallel discrete event simulation algorithm has been developed in which communication between logical processes is achieved using Cilk's virtual memory model, dag consistent shared memory. The simulation executes in cycles, where each cycle involves a divide and conquer computation. Although local lookahead information can be exploited, the algorithm is robust in that it also calculates a global simulation time for each cycle. It can therefore be used for applications where zero lookahead may occur.","Title: Incremental HLA-based distributed simulation cloning\nYear: 2004\n\nAbstract: Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same execution session. The goal is to optimize the execution time for evaluating different scenarios by avoiding repeated computation. In terms of High Level Architecture (HLA) based simulations, a federate may make clones to explore different scenarios at decision points. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected. This paper discusses the theory and issues involved in incremental distributed simulation cloning, which employs an event checking algorithm to ensure accurate sharing and initiates cloning only when absolutely necessary. Experiments have been performed to compare the performance of entire cloning and incremental cloning mechanisms. The experimental results indicate that cloning technologies can effectively reduce the time of executing multiple scenarios, and the incremental cloning mechanism significantly surpasses entire cloning in execution efficiency.","Title: Evolving Optimal and Diversified Military Operational Plans for Computational Red Teaming\nYear: 2012\n\nAbstract: Computational Red teaming (CRT) is a simulation-based optimization application utilized by defense analysts to uncover vulnerabilities of operational plans. In CRT, agent-based simulation models of military scenarios are automatically analyzed and modeled using evolutionary computation techniques. The CRT optimization process aims at identifying simulation models which exhibit emergent system behaviors of interest, e.g., when the adversary (called “Red”) breaks the defensive (“Blue”) strategies. Numerous multiobjective evolutionary algorithms (MOEAs) have been applied to CRT; however, the elitist and converging nature of these Pareto-based optimization algorithms typically leads to the generation of optimal, with respect to the Pareto front, but poorly diversified adversarial operational plans. As a result, the near-optimal alternative strategies are omitted; this considerably limits the applicability of CRT when considering the decision makers point of view. We propose a diversity enhancement scheme for MOEAs which uses the diversity contribution of individual solutions in the aggregated (combining both the objective and decision variable spaces) space to compute the fitness assignment. This feature enables both the exploitation of Pareto-optimal solutions whilst promoting diversification of the solutions in the decision variable space. Our experimental results indicate that this diversity enhancement mechanism can effectively resolve the diversification issue and, ultimately, enhance CRT to assist decision making.","Title: A review of interactive narrative systems and technologies: a training perspective\nYear: 2015\n\nAbstract: an emerging form of digital entertainment, the interactive narrative has attracted great attention from researchers over the past decade. Recently, there has been an emerging trend to apply interactive narratives to training and simulation. An interactive narrative system allows players to proactively interact with simulated entities in a virtual world and have the ability to alter the progression of a storyline. In simulation-based training, the use of an interactive narrative system enables the possibility to offer engaging, diverse and personalized narratives or scenarios for different training purposes. This paper provides a review of interactive narrative systems and technologies from a training perspective. Specifically, we first propose a set of key requirements in developing interactive narrative systems for simulation-based training. Then we review nine representative existing systems with respect to their system architectures, features and related mechanisms. To examine their applicability to training, we investigate and compare the reviewed systems based on the functionalities and modules that support the proposed requirements. Furthermore, we discuss some open research issues on the future development of interactive narrative technologies for training applications.","Title: Let's depart together: Efficient play request dispatching in cloud gaming\nYear: 2014\n\nAbstract: In this paper, we study the problem of how to dispatch the play requests to the cloud servers in a cloud gaming system. We show that the dispatching strategy of play requests may heavily affect the total service cost of the cloud gaming system. The play request dispatching problem can be considered as a variant of the dynamic bin packing problem. However, we show that the classical bin packing algorithms such as First Fit and Best Fit are not efficient in dispatching the play requests in cloud gaming due to the diurnal workload pattern of online games. To address this issue, we propose an efficient request dispatching algorithm that assigns the play requests according to the predicted ending times of the game sessions. Through extensive evaluations using real online gaming traces, we show that the proposed dispatching algorithm can significantly reduce the resource waste of the cloud servers and thus decrease the total service cost compared to the First Fit and Best Fit algorithms.","Title: Self-Learning Gene Expression Programming\nYear: 2016\n\nAbstract: In this paper, a novel self-learning gene expression programming (GEP) methodology named SL-GEP is proposed to improve the search accuracy and efficiency of GEP. In contrast to the existing GEP variants, the proposed SL-GEP features a novel chromosome representation where each chromosome is embedded with subfunctions that can be deployed to construct the final solution. As part of the chromosome, the subfunctions are self-learned or self-evolved by the proposed algorithm during the evolutionary search. By encompassing subfunctions or any partial solution as input arguments of another subfunction, the proposed SL-GEP facilitates the formation of sophisticated, higher-order, and constructive subfunctions that improve the accuracy and efficiency of the search. Further, a novel search mechanism based on differential evolution is proposed for the evolution of chromosomes in the SL-GEP. The proposed SL-GEP is simple, generic and has much fewer control parameters than the traditional GEP variants. The proposed SL-GEP is validated on 15 symbolic regression problems and six even parity problems. Experimental results show that the proposed SL-GEP offers enhanced performances over several state-of-the-art algorithms in terms of accuracy and search efficiency.","Title: Dynamic Bin Packing for On-Demand Cloud Resource Allocation\nYear: 2016\n\nAbstract: Dynamic Bin Packing (DBP) is a variant of classical bin packing, which assumes that items may arrive and depart at arbitrary times. Existing works on DBP generally aim to minimize the maximum number of bins ever used in the packing. In this paper, we consider a new version of the DBP problem, namely, the MinTotal DBP problem which targets at minimizing the total cost of the bins used over time. It is motivated by the request dispatching problem arising from cloud gaming systems. We analyze the competitive ratios of the modified versions of the commonly used First Fit, Best Fit, and Any Fit packing (the family of packing algorithms that open a new bin only when no currently open bin can accommodate the item to be packed) algorithms for the MinTotal DBP problem. We show that the competitive ratio of Any Fit packing cannot be better than + 1, where is the ratio of the maximum item duration to the minimum item duration. The competitive ratio of Best Fit packing is not bounded for any given . For First Fit packing, if all the item sizes are smaller than 1 of the bin capacity ( > 1 is a constant), the competitive ratio has an upper bound of 1 + 3 1 + 1. For the general case, the competitive ratio of First Fit packing has an upper bound of 2 + 7. We also propose a Hybrid First Fit packing algorithm that can achieve a competitive ratio no larger than 5 4 + 19 4 when is not known and can achieve a competitive ratio no larger than + 5 when is known.","Title: Density-based evolutionary framework for crowd model calibration.\nYear: 2015\n\nAbstract: Crowd modeling and simulation is an important and active research field, with a wide range of applications such as computer games, military training and evacuation modeling. One important issue in crowd modeling is model calibration through parameter tuning, so as to produce desired crowd behaviors. Common methods such as trial-and-error are time consuming and tedious. This paper proposes an evolutionary framework to automate the crowd model calibration process. In the proposed framework, a density-based matching scheme is introduced. By using the dynamic density of the crowd overtime, and a weight landscape to emphasize important spatial regions, the proposed matching scheme provides a generally applicable way to evaluate the simulated crowd behaviors. Besides, a hybrid search mechanism based on differential evolution is proposed to efficiently tune parameters of crowd models. Simulation results demonstrate that the proposed framework is effective and efficient to calibrate the crowd models in order to produce desired macroscopic crowd behaviors. (C) 2014 Elsevier B.V. All rights reserved.","Title: Un-identical federate replication structure for improving performance of HLA-based simulations.\nYear: 2014\n\nAbstract: •Propose an un-identical replication structure for improving performance of HLA-based simulations.•Use a middleware approach to support federate replication transparently.•Develop message exchange and time management mechanisms to handle different behaviors of un-identical replicas.•Provide correctness proof of the un-identical replication structure.•Achieve significant performance enhancement with good scalability and marginal overhead.","Title: Hierarchical resource management for enhancing performance of large-scale simulations on data centers\nYear: 2014\n\nAbstract: More and more interests have been shown to move large-scale simulations on modern data centers composed of a large number of virtualized multi-core computers. However, the simulation components (Federates) consolidated in the same computer may have imbalanced simulation workloads. Similarly, the computers involved in the same simulation execution (Federation) may also have imbalanced simulation workloads. Hence, federates may waste a lot of computer resources on time synchronization with each other. In this paper, a hierarchical resource management system is proposed to enhance simulation execution performance. Federates in the federation are enraptured in their individual Virtual Machines (VMs), which are consolidated on a group of virtualized multi-core computers. On the computer level, multiple VMs share the resource of the computer according to the simulation workloads of their corresponding federates. On the federation level, some VMs are migrated for workload balance purpose. Therefore, computer resources are fully utilized to conduct useful simulation workloads, avoiding the synchronization overheads. Experiments using synthetic and real simulation workloads have verified that the hierarchical resource management system enhances simulation performance significantly.","Title: Efficient graph-based dynamic load-balancing for parallel large-scale agent-based traffic simulation\nYear: 2014\n\nAbstract: One of the issues of parallelizing large-scale agent-based traffic simulations is partitioning and load-balancing. Traffic simulations are dynamic applications where the distribution of workload in the spatial domain constantly changes. Dynamic load-balancing at run-time has shown better efficiency than static partitioning in many studies. However, existing work has only focused on geographic partitioning methods which do not consider the minimization of communication overhead. In this paper, a graph-based dynamic load-balancing mechanism which minimizes the communication overhead during load-balancing operations is developed. Its efficiency is investigated in the agent-based traffic simulator SEMSim Traffic using real world traffic data. Experiment results show that it has significantly better performance than static graph partitioning methods in improving the overall speed of the simulation.","Title: EA-based evacuation planning using agent-based crowd simulation\nYear: 2014\n\nAbstract: Safety planning for crowd evacuation is an important and active research topic nowadays. One important issue is to devise the evacuation plans of individuals in emergency situations so as to reduce the total evacuation time. This paper proposes a novel evolutionary algorithm (EA)-based methodology, together with agent-based crowd simulation, to solve the evacuation planning problem. The proposed method features a novel segmentation strategy which divides the entire evacuation region into sub-regions based on a discriminant function. Each sub-region is assigned with an exit gate, and individuals in a sub-region will run toward the corresponding exit gate for evacuation. In this way, the evacuation planning problem is converted to a symbolic regression problem. Then an evolutionary algorithm, using agent-based crowd simulation as fitness function, is developed to search for the global optimal solution. The simulation results on different scenarios demonstrate that the proposed method is effective to reduce the evacuation time.","Title: Evolving Agent-based Models Using Complexification Approach.\nYear: 2014\n\nAbstract: This paper focuses on parameter search for multi-agent based models using evolutionary algorithms. Large numbers and variable dimensions of parameters require a search method which can efficiently handle a high dimensional search space. We are proposing the use of complexification as it emulates the natural way of evolution by starting with a small constrained search space and expanding it as the evolution progresses. We examined the effects of this method on an EA by evolving parameters for two multi-agent based models.","Title: On dynamic bin packing for resource allocation in the cloud\nYear: 2014\n\nAbstract: Dynamic Bin Packing (DBP) is a variant of classical bin packing, which assumes that items may arrive and depart at arbitrary times. Existing works on DBP generally aim to minimize the maximum number of bins ever used in the packing. In this paper, we consider a new version of the DBP problem, namely, the MinTotal DBP problem which targets at minimizing the total cost of the bins used over time. It is motivated by the request dispatching problem arising in cloud gaming systems. We analyze the competitive ratios of the commonly used First Fit, Best Fit, and Any Fit packing (the family of packing algorithms that open a new bin only when no currently opened bin can accommodate the item to be packed) algorithms for the MinTotal DBP problem. We show that the competitive ratio of Any Fit packing cannot be better than the max/min item interval length ratio μ. The competitive ratio of Best Fit packing is not bounded for any given μ. For First Fit packing, if all the item sizes are smaller than W⁄k (W is the bin capacity and k≥1 is a constant), it has a competitive ratio of k⁄k-1μ + 6k⁄k-1 + 1. For the general case, First Fit packing has a competitive ratio of 2μ + 13. We also propose a Modified First Fit packing algorithm that can achieve a competitive ratio of 8⁄7μ + 55⁄7 when μ is not known and can achieve a competitive ratio of μ + 8 when μ is known.","Title: High-dimensional objective-based data farming\nYear: 2011\n\nAbstract: In objective-based data farming, decision variables of the Red Team are evolved using evolutionary algorithms such that a series of rigorous Red Team strategies can be generated to assess the Blue Team's operational tactics. Typically, less than 10 decision variables (out of 1000+) are selected by subject matter experts (SMEs) based on their past experience and intuition. While this approach can significantly improve the computing efficiency of the data farming process, it limits the chance of discovering “surprises” and moreover, data farming may be used only to verify SMEs' assumptions. A straightforward solution is simply to evolve all Red Team parameters without any SME involvement. This modification significantly increases the search space and therefore we refer to it as high-dimensional objective-based data farming (HD-OBDF). The potential benefits of HD-OBDF include: possible better performance and information about more important decision variables. In this paper, several state-of-the-art multi-objective evolutionary algorithms are applied in HD-OBDF to assess their suitability in terms of convergence speed and Pareto efficiency. Following that, we propose two approaches to identify dominant/key evolvable parameters in HD-OBDF - decision variable coverage and diversity spread.","Title: Map stream: Initializing what-if analyses for real-time symbiotic traffic simulations\nYear: 2014\n\nAbstract: In the context of a city-scale symbiotic traffic simulation, real-time data about the location of many vehicles are obtained in the form of a continuous data-stream. In this paper, we present a scalable solution for performing map-matching using sliding-windows over a GPS data-stream onto a digital road network for initializing the what-if analysis process involved in symbiotic simulations. We focus on the optimizations performed to ensure that the latency associated with the map-matching process is low while maintaining a high degree of accuracy. Experimental results reveal the range in terms of sampling interval and noise for acceptable reliability and latency.","Title: Adapting a supply-chain simulation for HLA\nYear: 2000\n\nAbstract: Supply-chain management covers the planning and management of material and information from the manufacturer, through the distributors, and finally to the customer. With the globalization of markets, the optimization of supply-chain management becomes increasingly important. Simulation of supply-chains can help in the optimization process by evaluating the impact of alternative policies. To support the reusability of existing simulation models in a supply-chain simulation, a common standard is required for enabling the interoperability amongst different simulation programs through a well-defined interface. The High Level Architecture (HLA) is architecture for reuse and interoperation of simulations. This paper reports our experiences on employing the HLA to support reusability and interoperability in semiconductor supply-chain simulation. Our experiments show that by fine-tuning the integration of the application with the HLA Run-Time Infrastructure (RTI), considerable performance improvements can be achieved.","Title: Emergence by strategy: Flocking boids and their fitness in relation to model complexity\nYear: 2013\n\nAbstract: In this paper we aim to examine emergent properties of agent-based models by using evolutionary algorithms. Taking the model of flocking boids as an example, we study and try to understand how the pressure of natural selection towards strategic behavior can result in emergent behavior. Furthermore we investigate how an increase of complexity in the model affects those properties and discover some counter-intuitive behavior in the process.","Title: Consistency-Aware Zone Mapping and Client Assignment in Multi-Server Distributed Virtual Environments\nYear: 2015\n\nAbstract: In Distributed Virtual Environments (DVEs), the primary task is to maintain a consistent view of the virtual world among all users. Multi-server architecture has been shown to have good scalability to support a large population of users in DVEs. In the zone-based Multi-server Distributed Virtual Environment (MSDVE), zone mapping and client assignment are two key issues in the design of an efficien...","Title: Differential evolution with sensitivity analysis and the Powell's method for crowd model calibration\nYear: 2015\n\nAbstract: This paper proposes a novel evolutionary algorithm named differential evolution with sensitivity analysis and the Powell's method (DESAP) for model calibration. The proposed DESAP owns three main features. First, an entropy-based sensitivity analysis operation is introduced to dynamically identify important parameters of the model as evolution progresses online. Second, the Powell's method is performed periodically to fine-tune the important parameters of the best individual in the population. Finally, in each generation, the evolutionary operators are performed on a small number of better individuals in the population. These new search mechanisms are integrated into the differential evolution framework to improve the search efficiency. To validate its effectiveness, the proposed DESAP is applied to two crowd model calibration cases. The results demonstrate that the proposed DESAP outperforms several model calibration methods in terms of solution accuracy and search efficiency. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.","Title: Evolving agent-based models using self-adaptive complexification\nYear: 2015\n\nAbstract: This paper focuses on parameter search for multi-agent based models using evolutionary algorithms. Large numbers and variable dimensions of parameters require an optimization method which can efficiently handle a high dimensional search space. We are proposing the use of complexification as it emulates the natural way of evolution by starting with a small constrained search space and expanding it as the evolution progresses. To further improve performance we suggest and experiment with methods of self-adaptation to enable the algorithm to adjust its parameters individually to the problem at hand. We examined the effects of these methods on an EA by evolving parameters for two multi-agent based models. (C) 2015 Elsevier B.V. All rights reserved.","Title: Effects of topology and buffering on a processor farm\nYear: 1999\n\nAbstract: The advantages of a processor farm include dynamic load balancing and low-complexity implementation. The major disadvantage is work starvation. Research has proposed different application-specific or platform-specific models of a processor farm. Few have attempted to study the performance characteristics of a processor farm model under varying system parameters. In this paper, we present the design of a distributed-memory processor farm with a topology-independent communications process architecture which offers reduced work starvation by providing minimal routes for work dissemination and results acknowledgment. We evaluate its performance characteristics under varying network size, topology and buffer requirements.","Title: Play Request Dispatching for Efficient Virtual Machine Usage in Cloud Gaming\nYear: 2015\n\nAbstract: Cloud gaming is becoming increasingly popular. The basic idea of cloud gaming is to run games on cloud servers and let players interact with games through thin clients. As the player population grows, the cloud gaming service provider needs to maintain a large number of cloud servers for running the game instances requested by the players. A primary concern of the cloud gaming service provider is ...","Title: Transparent three-phase Byzantine fault tolerance for parallel and distributed simulations.\nYear: 2016\n\nAbstract: •Propose a three-phase Byzantine Fault Tolerance (BFT) mechanism.•Integrate replication, checkpointing and message logging techniques.•Develop the BFT mechanism in a transparent manner.•Remove epidemic effects of Byzantine failures.•Evaluate the BFT mechanism using a real-world simulation model.","Title: SEMSim Cloud Service: Large-scale urban systems simulation in the cloud\nYear: 2015\n\nAbstract: Large-scale urban systems simulations are complex and with a large number of active simulation entities the computational workload is extensive. Workstation computers have only limited capabilities of delivering results for large-scale simulations. This leads to the problem that many researchers and engineers have to either reduce the scope of their experiments or fail to execute as many experiments as they would like in a given time frame. The use of high-performance computing (HPC) infrastructure offers a solution to the problem. Users of such simulations are often domain experts with no or little experience with HPC environments. In addition users do not necessarily have access to an HPC. In this paper we propose an architecture for a cloud-based urban systems simulation platform which specifically aims at making large-scale simulations available to typical users. The proposed architecture also addresses the issue of data confidentiality. In addition we describe the Scalable Electro-Mobility Simulation (SEMSim) Cloud Service that implements the proposed architecture.","Title: An Asynchronous Synchronization Strategy for Parallel Large-scale Agent-based Traffic Simulations\nYear: 2015\n\nAbstract: Large-scale agent-based traffic simulation is a promising tool to study the road traffic and help solving traffic problems, such as congestion and high emission in megacities. Such simulation requires high computational resource which triggers the need for parallel computing. The parallelization of agent-based traffic simulations is generally performed by decomposing the simulation space into spatial subregions. The agent models contained by each subregion are executed by Logical Processes (LPs). As the simulated system evolves over the simulation time in individual LPs, synchronization among LPs is required due to data dependencies. Existing work has used global barriers for synchronization which is a type of synchronous synchronization method. However, global barriers have very low efficiency due to the waiting of processes at barriers. High synchronization overhead is still one of the major performance issues in parallel large-scale agent-based traffic simulations. In this paper, we proposed a novel asynchronous conservative synchronization strategy named Mutual Appointment (MA) to address this issue. MA removes global barriers and allows LPs to communicate individually. Since the efficiency of conservative synchronization relies on the lookahead of the simulated system, a heuristic was developed to increase the lookahead in agent-based traffic simulations. It takes advantage of the intrinsic uncertainties in traffic simulations. MA together with the lookahead heuristic forms the Relaxed Mutual Appointment (RMA) strategy. Its efficiency was investigated in the parallel agent-based traffic simulator SEMSim Traffic using real world traffic data. Experiment results showed that the MA strategy improved the speed-up of the parallel simulation compared to the barrier method, and the RMA strategy further improved the MA strategy by reducing the number of synchronization messages significantly.","Title: Traffic Simulation Performance Optimization through Multi-Resolution Modeling of Road Segments\nYear: 2015\n\nAbstract: In an agent-based traffic simulation the level of detail is crucial to the system's runtime performance as well as the fidelity of the results. Therefore, different model abstractions have been used throughout literature. Macroscopic, mesoscopic and microscopic models have their use-cases and benefits. Microscopic traffic simulations have a high level of detail but at the same time require a large amount of computational resources. In a large traffic network of a mega-city or an entire country, the use of a complete microscopic simulation is just not feasible. The resource required to do so are for most use-cases in no relation to the actual outcome. We propose a hybrid traffic simulation model that uses both, a high-resolution agent based microscopic simulation alongside a lower resolution flow-based macroscopic simulation for specific road segments. The problem with using different simulation models is the fidelity at the boundary between such simulation models. This fidelity discrepancy is caused by the difficulties with aggregation and disaggregation passing through the boundary. We show, in this paper, that the computational performance (simulation time) can be improved by $20\\\\%$ while maintaining a relative high accuracy of below $5\\\\%$ deviation from a pure microscopic simulation.","Title: Cloning Agent-based Simulation on GPU\nYear: 2015\n\nAbstract: Simulation cloning is an efficient way to analyze multiple configurations in a parameter exploration task. This paper presents a generic approach to perform incremental agent-based simulation cloning and discusses its implementation on GPU. Compared with the incremental cloning of parallel and distributed simulation (PADS), cloning agent-based simulation (ABS) has new challenges due to the unique way how ABS is executed. In this paper, to support incremental cloning, mechanisms for both actively and passively cloning agents are proposed. A scheme to maintain the correct context of each cloned ABS instance is developed. In addition, a strategy to restrain the propagation of passive cloning in order to maximize computation sharing amongst cloned ABS instances is also investigated. The implementation of our proposed approach on GPU supports concurrent execution of agents within each simulation instance as well as concurrent execution of multiple simulation instances. Performance of the proposed approach is evaluated and analyzed using a case study of an agent-based evacuation simulation on a NVIDIA Quadro 2000 GPU. Our experiment results demonstrate that cloning can significantly speed up the overall parameter exploration task. The proposed approach achieves 2.4 to 5.1 times speedup for parameter exploration tasks containing 8 to 125 simulation instances that evaluate different parameter configurations.","Title: A data-driven approach for online adaptation of game difficulty\nYear: 2015\n\nAbstract: Dynamic adaptation of games with the objective of catering to the individual players' level of standard is an emerging and challenging research area of artificial intelligence in digital game. In this paper, we propose a data-driven approach for dynamic adaptation of game scenario difficulties. The goal is to fit the performance of the player to the desired conditions set by the designer. To this end, the data on player's in-game performance and dynamic game states are utilized for making adaptation decisions. Trained artificial neural networks are used to capture the relationship between dynamic game state, player performance, adaptation decision and the resultant game difficulty. Based on the predicted difficulty, adaptation of both direction and magnitude can be performed more effectively. Experimental study on a training game application is presented to demonstrate the efficiency and stability of the proposed approach.","Title: Learning Behavior Patterns from Video: A Data-driven Framework for Agent-based Crowd Modeling\nYear: 2015\n\nAbstract: This paper proposes a generic data-driven crowd modeling framework to generate crowd behaviors that can match the video data. The proposed framework uses a dual-layer mechanism to model the crowd behaviors. The bottom layer models the microscopic collision avoidance behaviors, while the top layer models the macroscopic crowd behaviors such as the goal selection patterns and the path navigation patterns. Based on the dual-layer mechanism, an automatic learning method is proposed to learn the model components from video data. To validate its effectiveness, the proposed framework is applied to generate the crowd behaviors in New York Grand Central Terminal. The simulation results demonstrate that the proposed method is able to construct effective model that can generate the desired emergent crowd behaviors and can offer promising prediction performance.","Title: Efficient Neighbor Searching for Agent-Based Simulation on GPU\nYear: 2014\n\nAbstract: This paper introduces a strategy to accelerate neighbor searching in agent-based simulations on GPU platforms. Because of their autonomous nature, agents can be processed by threads concurrently on GPU, and the overall simulation can be accelerated consequently. Each agent will simultaneously carry out a sense-think-act cycle in every time step. The neighbor searching is a crucial part in the sensing stage. Detecting and accessing neighbors is a memory intensive task and often becomes the major time consumer in an agent-based simulation. Our contribution, an enhanced neighbor sharing strategy, greatly speeds up this procedure when comparing with CPU implementations. The strategy is developed from a global-memory-only implementation, and then gradually improved by efficiently utilizing the much faster shared memory. In our case studies, speedups of 89.08 and 11.51 are obtained on an NVIDIA Tesla K20 GPU compared with the sequential implementation and OpenMP parallel implementation respectively on an Intel Xeon E5-2670 CPU.","Title: Evaluation of Crowd Models in Low Density Scenarios Using Real-World Crowd Data.\nYear: 2015\n\nAbstract: In this paper, we evaluate the simulation accuracy of five crowd models: (a) RVO2; (b) social force; (c) approximate nearest neighbor search (ANN); (d) perception-action graph (PAG); and (e) clustering-based model (CLUST) by comparing the simulation results against the real world motion data quantitatively on six metrics: (a) travel time; (b) travel distance; (c) deviation; (d) speed change; (e) angle change; and (f) energy. We use real pedestrians' motion data in two scenarios with different crowd densities and main walking directions as the ground truth. The results demonstrate that the CLUST model outperforms other models in terms of most metrics, while the PAG model has the worst accuracy in all metrics. The performance of the social force model depends largely on the scenario. We also conduct a qualitative comparison of five models on a simple scenario with only two agents, in order to give an indication of the differences and similarities between models. We find that the simulated trajectories of the RVO2 and social force models are more symmetric and regular than that generated by the ANN, PAG and CLUST models. And the ANN, PAG and CLUST models' trajectories reflect the motion behaviors of the input data used to train the models. Finally, we compare the simulation frame rates of five models on two real-world scenarios and show that by applying certain data pre-processing techniques, the PAG and CLUST models can achieve better run-time performances than the ANN model, but still run slower than the RVO2 and social force models.","Title: MASTER: Multi-platform Application Streaming Toolkits for Elastic Resources\nYear: 2015\n\nAbstract: In this demonstration, we propose MASTER, a set of toolkits for cross-platform application streaming that is able to utilize elastic resources on public clouds. MASTER has many useful features. It provides full control of resource acquisition and request dispatching, requires only a browser on the client side for user interactions, and incorporates an input transformer to assist touchscreen device users to naturally interact with desktop applications that need keystroke and mouse control. MASTER also supports session concurrency (serving multiple streaming sessions on a single cloud server instance), thereby improving resource utilization and cutting the cloud bill.","Title: Crowd evacuation planning using cartesian genetic programming and agent-based crowd modeling.\nYear: 2015\n\nAbstract: This paper proposes a new evolutionary algorithm-based methodology for optimal crowd evacuation planning. In the proposed methodology, a heuristic-based evacuation scheme is firstly introduced. The key idea is to divide the region into a set of sub-regions and use a heuristic rule to dynamically recommend an exit to agents in each sub-region. Then, an evolutionary framework based on the Cartesian Genetic Programming algorithm and an agent-based crowd simulation model is developed to search for the optimal heuristic rule. By considering dynamic environment features to construct the heuristic rule and using multiple scenarios for training, the proposed methodology aims to find generic and efficient heuristic rules that perform well on different scenarios. The proposed methodology is applied to guide people's evacuation behaviors in six different scenarios. The simulation results demonstrate that the heuristic rule offered by the proposed method is effective to reduce the crowd evacuation time on different scenarios.","Title: Tutorial on a modeling and simulation cloud service.\nYear: 2015\n\nAbstract: For large-scale urban system simulations the computing power of traditional workstations is not sufficient. The move to High Performance Computing clusters is a viable solution. Users of such simulations are domain experts with little knowledge in computer science and optimization of such simulations. The access to HPC resources is also not available. Vendors have not sufficiently addressed this. This leads to the conclusion of moving the computational demand to the cloud, where the on-demand culture for resources has been expanding. In this tutorial we will present an approach of how to work with an entirely cloud-based solution for modeling and simulation, with an exemplary implementation of an urban traffic simulation cloud service. Since the computational offload from the workstation to a remote computing entity also allows the use of novel user interfaces (design and devices), through the use of RESTful interfaces, use-case applicable interfaces for simulations can also be created.","Title: Design of supply chain topology to mitigate demand and supply risks.\nYear: 2015\n\nAbstract: To achieve competitive advantage, companies have been driven to improve their supply chain by outsourcing their non-core business. However, this increases the external risks, such as the demand and supply risks. Companies face challenges in defining effective supply chain topology to mitigate supply chain risks. In this research, we design supply chain network topologies to mitigate the demand and supply risks. Four supply chain network topologies have been designed to represent different supply chain strategies: efficient, responsive, risk-hedging, and agile strategies. An agent-based modeling approach is proposed to evaluate the performance of the supply chain network topologies under different demand and supply risk scenarios. From the results, we can identify the effective supply chain network topology to mitigate the disruption for a particular risk scenario.","Title: Trusted Block as a Service: Towards Sensitive Applications on the Cloud\nYear: 2011\n\nAbstract: Cloud computing grows rapidly as today's advanced information technology. However, by allowing outsourcing computation on the Cloud, users risk of disclosing privacy and obtaining forged results. These potential threats block sensitive applications to join the Cloud. In this paper, we characterize sensitive applications on the Cloud (SAND) problem and define two critical security requirements: confidentiality and verifiability. The former refers to the protection of sensitive programs/data from disclosing to other users or even the Cloud administrators. The latter concerns with user's capability to verify whether computing results are faithfully calculated. To address SAND, we propose a new Cloud model, Trusted Block as a Service (TBaaS), to provide a confidential and verifiable environment for each sensitive application. TBaaS limits Cloud provider's access of sensitive applications while granting user the ability to verify whether the computation is faithfully carried out. Moreover, it offers high flexibility and low performance overhead.","Title: Data-Driven Dynamic Adaptation Framework for Multi-agent Training Game.\nYear: 2015\n\nAbstract: In this paper, we present a dynamic adaptation framework to adapt the game scenarios for a multi-agent training game. We consider the problem where a trainee has to practice along multiple objectives during the training, and each objective is assigned with a desired difficulty level. The proposed dynamic adaptation approach takes into account of individual player's playing ability as well as the dynamic game circumstance to determine how to adapt the game scenario. We utilize artificial neural networks to construct a data-driven prediction model to estimate the effect of taking certain adaptation to the game. Based on the prediction model, our adaptation framework can determine both the direction and quantity of the adaptation. The performance of the proposed framework is testified in a food distribution training game and the results demonstrate the effectiveness of our adaptation framework.","Title: Supporting efficient execution of continuous space agent-based simulation on GPU.\nYear: 2016\n\nAbstract: Using agent-based simulation ABS to analyze complex adaptive systems gains growing popularity over the past decades. One of the fundamental issues in ABS is to increase the execution speed. In this paper, we identify two common modules that widely exist in ABS applications, namely, the agent management module and the agent interaction module. Improving the efficiency of these two common modules can significantly speed up the ABS execution in general. GPU architecture, programming model, and memory hierarchy are studied. Effective strategies on GPU are proposed when we design the two modules. The first contribution of this work is to propose an AgentPool data structure to handle agent creation and deletion on GPU. The second contribution is an efficient agent interaction module, which is designed by carefully utilizing the GPU memory hierarchy. To demonstrate effectiveness and generality, the proposed strategies are applied to a range of ABS applications, including game-of-life, flocking boids, prey-and-predator, and the social force-based crowd simulation. The simulation results demonstrate that the proposed strategies achieve better performance than the commonly used CPU and GPU ABS framework, namely, Mason and FLAME, for ABS applications using continuous space. Copyright © 2016 John Wiley & Sons, Ltd.","Title: Learning behavior patterns from video for agent-based crowd modeling and simulation.\nYear: 2016\n\nAbstract: This paper proposes a novel data-driven modeling framework to construct agent-based crowd model based on real-world video data. The constructed crowd model can generate crowd behaviors that match those observed in the video and can be used to predict trajectories of pedestrians in the same scenario. In the proposed framework, a dual-layer architecture is proposed to model crowd behaviors. The bottom layer models the microscopic collision avoidance behaviors, while the top layer models the macroscopic crowd behaviors such as the goal selection patterns and the path navigation patterns. An automatic learning algorithm is proposed to learn behavior patterns from video data. The learned behavior patterns are then integrated into the dual-layer architecture to generate realistic crowd behaviors. To validate its effectiveness, the proposed framework is applied to two different real world scenarios. The simulation results demonstrate that the proposed framework can generate crowd behaviors similar to those observed in the videos in terms of crowd density distribution. In addition, the proposed framework can also offer promising performance on predicting the trajectories of pedestrians.","Title: A Role-dependent Data-driven Approach for High Density Crowd Behavior Modeling.\nYear: 2016\n\nAbstract: In this paper, we propose a role-dependent data-driven modeling approach to simulate pedestrians' motion in high density scenes. It is commonly observed that pedestrians behave quite differently when walking in dense crowd. Some people explore routes towards their destinations. Meanwhile, some people deliberately follow others, leading to lane formation. Based on these observations, two roles are included in the proposed model: leader and follower. The motion behaviors of leader and follower are modeled separately. Leaders' behaviors are learned from real crowd motion data using state-action pairs while followers' behaviors are calculated based on specific targets that are obtained dynamically during the simulation. The proposed role-dependent data-driven model is trained on crowd video data in one dataset and is then applied to two other different datasets to test its generality and effectiveness. The simulation results demonstrate that the proposed role-dependent data-driven model is capable of simulating crowd behaviors in crowded scenes realistically and reproducing collective crowd behaviors such as lane formation.","Title: Online Data Extraction for Large-Scale Agent-Based Simulations.\nYear: 2016\n\nAbstract: Cloud-based simulation systems reduce the upfront hardware costs of running high-performance experiments and increases the ease with which simulation experiments can be repeated. The data being generated by simulations can be large. Commonly used data storage systems such as relational databases can handle large amounts of data, but the analysis is a challenging problem. Moreover, handling this amount of data in cloud services can be both expensive (bandwidth and storage costs) and time-consuming. However, a lot of the data that is generated by agent-based simulations does not contribute directly to the purpose of the experiment being conducted. We propose an extension to cloud-based simulation systems that rather than storing raw simulation output data, uses stream data processing to generate the result dataset while the simulation is running. This can then be used to store only the data required for later use, this saving both time and money.","Title: A Hyper-Heuristic Framework for Agent-Based Crowd Modeling and Simulation: (Extended Abstract).\nYear: 2016\n\nAbstract: This paper proposes a hyper-heuristic crowd modeling framework to generate realistic crowd dynamics that can match video data. In the proposed framework, motions of agents are driven by a high-level heuristic (HH) which intelligently selects way-points for agents based on the current situations. Three low-level heuristics are defined and used as building blocks of the HH. Based on the newly defined building blocks and fitness evaluation function, the Self-Learning Gene Expression Programming (SL-GEP) is utilized to automatically evolve a suitable HH. To test its effectiveness, the proposed framework is applied to learn suitable HHs based on real video data. The best HH learned is then applied to generate crowd simulations and the simulation results demonstrate that the proposed method is effective to generate realistic crowd dynamics.","Title: On First Fit Bin Packing for Online Cloud Server Allocation\nYear: 2016\n\nAbstract: Cloud-based systems often face the problem of dispatching a stream of jobs to run on cloud servers in an online manner. Each job has a size that defines the resource demand for running the job. Each job is assigned to run on a cloud server upon its arrival and the job departs after it completes. The departure time of a job, however, is not known at the time of its arrival. Each cloud server has a fixed resource capacity and the total resource demand of all the jobs running on a server cannot exceed its capacity at all times. The objective of job dispatching is to minimize the total cost of the servers used, where the cost of renting each cloud server is proportional to its running hours by \"pay-as-you-go\" billing. The above job dispatching problem can be modeled as a variant of the Dynamic Bin Packing (DBP) problem known as MinUsageTime DBP. In this paper, we develop new approaches to the competitive analysis of the commonly used First Fit packing algorithm for the MinUsageTime DBP problem, and establish a new upper bound of μ+4 on the competitive ratio of First Fit packing, where μ is the ratio of the maximum job duration to the minimum job duration. Our result significantly reduces the gap between the upper and lower bounds for the MinUsageTime DBP problem to a constant value independent of μ, and shows that First Fit packing is near optimal for MinUsageTime DBP.","Title: Traffic State Estimation Using Floating Car Data.\nYear: 2016\n\nAbstract: There is an increasing availability of floating car data both historic, in the form of trajectory datasets and real-time, in the form of continuous data streams. This paves the way for several advanced traffic management services such as current traffic state estimation, congestion and incident detection and prediction of the short-term evolution of traffic flow. In this paper, we present an analysis of using probe vehicles for reconstructing traffic state. We employ detailed agent-based microscopic simulations of a real world expressway to estimate the state from floating car data. The probe penetration required for accurate traffic state estimation is also determined.","Title: Adaptive Resilient Strategies For Supply Chain Networks\nYear: 2016\n\nAbstract: Due to globalization of economy, the supply chains are vulnerable to disruptive events. In addition, lean initiatives often lead to single supplier, which is vulnerable to supply disruption. In this paper, two strategies are proposed for generating supply chain networks to improve the resilience of supply chain networks: hierarchical preferential attachment and hierarchical random attachment. The supply chain resilience is evaluated using supply availability and the demand to supply ratio. Disruptions in the supply chain are modeled using random and targeted disruptions. The paper also designed an algorithm to recover the supply chain network from disruptions, based on the network attachment rules (preferential attachment and random attachment). Through a simulation study, the recovered supply chain is shown to have better resilience compared to a single supplier supply chain network.","Title: Server Allocation for Multiplayer Cloud Gaming.\nYear: 2016\n\nAbstract: Advances in cloud computing and GPU virtualization are allowing the game industry to move into a cloud gaming era. While shifting standalone video games to the cloud gaming mode is straightforward, adapting multiplayer online games to the cloud gaming paradigm faces unique challenges. In this paper, we consider multiplayer cloud gaming (MCG), which is the natural integration of multiplayer online gaming and cloud gaming paradigms. We formulate an MCG server allocation problem with the objective of minimizing the total server rental and bandwidth cost charged by the cloud to support an MCG session. We propose several efficient heuristics to address the MCG server allocation problem which is hard to solve optimally. We conduct extensive experiments using real Internet latency and cloud pricing data to evaluate the effectiveness of our proposed algorithms as well as several alternatives. Experimental results show that our best algorithm can achieve near-optimal cost under real-time latency constraints.","Title: IBED: Combining IBEA and DE for optimal feature selection in software product line engineering.\nYear: 2016\n\nAbstract: Abstract Software configuration, which aims to customize the software for different users (e.g., Linux kernel configuration), is an important and complicated task. In software product line engineering (SPLE), feature oriented domain analysis is adopted and feature model is used to guide the configuration of new product variants. In SPLE, product configuration is an optimal feature selection problem, which needs to find a set of features that have no conflicts and meanwhile achieve multiple design objectives (e.g., minimizing cost and maximizing the number of features). In previous studies, several multi-objective evolutionary algorithms (MOEAs) were used for the optimal feature selection problem and indicator-based evolutionary algorithm (IBEA) was proven to be the best MOEA for this problem. However, IBEA still suffers from the issues of correctness and diversity of found solutions. In this paper, we propose a dual-population evolutionary algorithm, named IBED, to achieve both correctness and diversity of solutions. In IBED, two populations are individually evolved with two different types of evolutionary operators, i.e., IBEA operators and differential evolution (DE) operators. Furthermore, we propose two enhancement techniques for existing MOEAs, namely the feedback-directed mechanism to fast find the correct solutions (e.g., solutions that satisfy the feature model constraints) and the preprocessing method to reduce the search space. Our empirical results have shown that IBED with the enhancement techniques can outperform several state-of-the-art MOEAs on most case studies in terms of correctness and diversity of found solutions.","Title: Sampling-based adaptive bounding evolutionary algorithm for continuous optimization problems.\nYear: 2017\n\nAbstract: This paper proposes a novel sampling-based adaptive bounding evolutionary algorithm termed SABEA that is capable of dynamically updating the search space during the evolution process for continuous optimization problems. The proposed SABEA adopts two bounding strategies, namely fitness-based bounding and probabilistic sampling-based bounding, to select a set of individuals over multiple generations and leverage the value information from these individuals to update the search space of a given problem for improving the solution accuracy and search efficiency. To evaluate the performance of this method, SABEA is applied on top of the classic differential evolution (DE) algorithm and a DE variant, and SABEA is compared to a state-of-the-art Distribution-based Adaptive Bounding Genetic Algorithm (DABGA) on a set of 27 selected benchmark functions. The results show that SABEA can be used as a complementary strategy for further enhancing the performance of existing evolutionary algorithms and it also outperforms DABGA. Finally, a practical problem, namely the model calibration for an agent-based simulation, is used to further evaluate SABEA. The results show SABEA’s applicability to diverse problems and its advantages over the traditional genetic algorithm-based calibration method and DABGA.","Title: Predicting The Duration Of Non-Recurring Road Incidents By Cluster-Specific Models\nYear: 2016\n\nAbstract: In metropolitan areas, about 50% of traffic delays are caused by non-recurring traffic incidents. Hence, accurate prediction of the duration of such events is critical for traffic management authorities. In this paper, we study the predictability of the duration of traffic incidents by considering various external factors. As incident data is typically sparse, training a large number of models (for instance, model for each road) is not possible. On the other hand, training one model for the entire network may not be a suitable solution, as such a model will be too generalized and consequently unsuitable for many relatively rare scenarios. Therefore, we propose to solve this issue by first grouping incidents through common latent similarities among them and then training data-driven predictors for each group. In our numerical analysis we consider incident data from Singapore and the Netherlands. Our results show that by training cluster-specific models we can reduce the prediction error by 19.41% for incidents in Singapore and by 17.8% for incidents in the Netherlands.","Title: RA2: Predicting Simulation Execution Time for Cloud-Based Design Space Explorations.\nYear: 2016\n\nAbstract: Design space exploration refers to the evaluation of implementation alternatives for many engineering and design problems. A popular exploration approach is to run a large number of simulations of the actual system with varying sets of configuration parameters to search for the optimal ones. Due to the potentially huge resource requirements, cloud-based simulation execution strategies should be considered in many cases. In this paper, we look at the issue of running large-scale simulation-based design space exploration problems on commercial Infrastructure-as-a-Service clouds, namely Amazon EC2, Microsoft Azure and Google Compute Engine. To efficiently manage cloud resources used for execution, the key problem would be to accurately predict the running time for each simulation instance in advance. This is not trivial due to the currently wide range of cloud resource types which offer varying levels of performance. In addition, the widespread use of virtualization techniques in most cloud providers often introduces unpredictable performance interference.\n\nIn this paper, we propose a resource and application-aware (RA2) prediction approach to combat performance variability on clouds. In particular, we employ neural network based techniques coupled with non-intrusive monitoring of resource availability to obtain more accurate predictions. We conducted extensive experiments on commercial cloud platforms using an evacuation planning design problem over a month-long period. The results demonstrate that it is possible to predict simulation execution times in most cases with high accuracy. The experiments also provide some interesting insights on how we should run similar simulation problems on various commercially available clouds.","Title: Data driven Adaptive Traffic simulation of an expressway.\nYear: 2016\n\nAbstract: Ubiquitous data from a variety of sources such as smart phones, vehicles equipped with GPS receivers and fixed sensors makes it an exciting time for the implementation of several Advanced Traffic Information and Management Systems (ATMS). Leveraging this data for current traffic state estimation along with short term predictions of traffic flow can have far reaching implications for the next generation of Intelligent Transportation Services (ITS). In this paper, we present our proof-of-concept of such a data driven traffic simulation for the short term prediction and control of traffic flow by simulating a real world expressway through dynamic ramp-metering.","Title: Automatic model construction for the behavior of human crowds.\nYear: 2017\n\nAbstract: Graphical abstractDisplay Omitted HighlightsWe propose an automatic methodology to learn generic crowd behavior rules from video data.We formulate the problem of finding behavioral rule from video data as a symbolic regression problem..The behavior rules learned by the proposed method are applicable to different scenarios that have similar behavior patterns.We apply the proposed method to real world datasets and the results have demonstrated the effectiveness of the proposed method. Designing suitable behavioral rules of agents so as to generate realistic behaviors is a fundamental and challenging task in many forms of computational modeling. This paper proposes a novel methodology to automatically generate a descriptive model, in the form of behavioral rules, from video data of human crowds. In the proposed methodology, the problem of modeling crowd behaviors is formulated as a symbolic regression problem and the self-learning gene expression programming is utilized to solve the problem and automatically obtain behavioral rules that match data. To evaluate its effectiveness, we apply the proposed method to generate a model from a video dataset in Switzerland and then test the generality of the model by validating against video data from the United States. The results demonstrate that, based on the observed movement of people in one scenario, the proposed methodology can automatically construct a general model capable of describing the crowd dynamics of another scenario in a different context (e.g., Switzerland vs. U.S.) as long as that the crowd behavior patterns are similar.","Title: Competitiveness of Dynamic Bin Packing for Online Cloud Server Allocation.\nYear: 2017\n\nAbstract: Cloud-based systems often face the problem of dispatching a stream of jobs to run on cloud servers in an online manner. Each job has a size that defines the resource demand for running the job. Each job is assigned to run on a cloud server upon its arrival and the job departs after it completes. The departure time of a job, however, is not known at the time of its arrival. Each cloud server has a ...","Title: Cloning Agent-Based Simulation.\nYear: 2017\n\nAbstract: Simulation cloning is an efficient way to analyze multiple configurations in a parameter exploration task. A simulation model usually contains a set of tunable parameters for exploring different configurations of a system. To evaluate different design alternatives, multiple simulation instances need to be launched, each evaluating a different parameter configuration. It usually takes a considerable amount of time to execute these simulation instances. Simulation cloning is proposed to reuse computations among simulation instances and to shorten the overall execution time. It is a challenging task to design cloning strategies to explore the computation sharing among simulation instances while maintaining the correctness of execution. In this article, we propose two agent-based simulation (ABS) cloning strategies, the top-down cloning strategy and the bottom-up cloning strategy. The top-down cloning strategy is initially designed and can only be applied to limited scenarios. The bottom-up cloning strategy is an improved strategy to overcome the limitation of the top-down cloning strategy. In the experiments, the effectiveness of the two strategies is analyzed. To show the performance advantages and generality of the bottom-up cloning strategy, a large-scale ABS parameter exploration task is performed, and results are discussed in the article.","Title: Relaxing Synchronization in Parallel Agent-Based Road Traffic Simulation.\nYear: 2017\n\nAbstract: Large-scale agent-based traffic simulation is computationally intensive. Parallel computing can help to speed up agent-based traffic simulation. Parallelization of agent-based traffic simulations is generally achieved by decomposing the road network into subregions. The agents in each subregion are executed by a Logical Process (LP). There are data dependencies between LPs which require synchronization of LPs. An asynchronous protocol allows LPs to progress and communicate asynchronously. LPs use lookahead to indicate the time to synchronize with other LPs. Larger lookahead means less frequent synchronization operations. High synchronization overhead is still a major performance issue of large-scale parallel agent-based traffic simulations. In this article, two methods to increase the lookahead of LPs for an asynchronous protocol are developed. They take advantage of uncertainties in traffic simulation to relax synchronization without altering simulation results statistically. Efficiency of the proposed methods is investigated in the parallel agent-based traffic simulator SEMSim Traffic. Experiment results showed that the proposed methods are able to reduce overall running time of the parallel simulation compared to existing methods.","Title: A Graph Partitioning Algorithm for Parallel Agent-Based Road Traffic Simulation.\nYear: 2017\n\nAbstract: A common approach of parallelising an agent-based road traffic simulation is to partition the road network into sub-regions and assign computations for each subregion to a logical process (LP). Inter-process communication for synchronisation between the LPs is one of the major factors that affect the performance of parallel agent-based road traffic simulation in a distributed memory environment. Synchronisation overhead, i.e., the number of messages and the communication data volume exchanged between LPs, is heavily dependent on the employed road network partitioning algorithm. In this paper, we propose Neighbour-Restricting Graph-Growing (NRGG), a partitioning algorithm which tries to reduce the required communication between LPs by minimising the number of neighbouring partitions. Based on a road traffic simulation of the city of Singapore, we show that our method not only outperforms graph partitioning methods such as METIS and Buffoon, for the synchronisation protocol used, but also is more resilient than stripe spatial partitioning when partitions are cut more ?nely.","Title: Minimizing Cost In Iaas Clouds Via Scheduled Instance Reservation\nYear: 2017\n\nAbstract: Regular diurnal patterns are often seen in the workloads of cloud-based online applications. This kind of non-stationary workloads changes the processing demands over time. To run application services with minimum costs, the number of cloud instances can be dynamically adjusted according to the workload variations. Recently, a new type of scheduled instances has emerged in the Infrastructure-as a-Service market to facilitate such configurations. Scheduled instances can be reserved based on a recurring schedule and they offer price discounts. Meanwhile, cloud vendors require minimum scheduled durations to avoid the overhead of frequently launching and terminating cloud instances. Coupled with traditional on-demand and reserved instances, it becomes more complicated for users to find the optimal combination of these three pricing options to minimize their monetary costs. For the new scheduled instances, not only the number of instances but also their start and stop times have to be decided. In this paper, we develop a fast and effective strategy to solve this problem. Based on the hourly workload distributions, we first compute the optimal number of instances to acquire for each pricing option. Then, we design a scheduling algorithm to arrange the scheduled instances in compliance with the restriction of their scheduled durations. Using the workloads of the LOL online game and the Wikipedia Mobile service as two case studies, the efficacy of our strategy is demonstrated.","Title: Fairness-aware Update Schedules for Improving Consistency in Multi-server Distributed Virtual Environments.\nYear: 2016\n\nAbstract: In Distributed Virtual Environments (DVEs), how to guarantee consistency and fairness is a primary concern for improving user experience. As the scale of DVE systems grows fast, multi-server architecture has been widely used in large scale DVEs such as Massively Multiplayer Online Games (MMOGs). In multi-server DVEs (MSDVEs), servers may get saturated with resources such as network bandwidth due to huge resource demand and workload variability. With resource limitations, state updates cannot be disseminated timely and inconsistency and unfairness will be greatly increased if the resources are not allocated properly. In this paper, we propose a fairness-aware state update scheduling algorithm which can minimize total inconsistency while guarantee fairness in MSDVEs under servers' network bandwidth constraints. Experimental results show that the proposed algorithm significantly improves the consistency and fairness compared to other existing update algorithms.","Title: On Server Provisioning for Cloud Gaming.\nYear: 2017\n\nAbstract: Cloud gaming has gained significant popularity recently due to many important benefits such as removal of device constraints, instant-on and cross-platform, etc. The properties of intensive resource demands and dynamic workloads make cloud gaming appropriate to be supported by an elastic cloud platform. Facing a large user population, a fundamental problem is how to provide satisfactory cloud gaming service at modest cost. We observe that software maintenance cost could be substantial compared to server running cost in cloud gaming. In this paper, we address the server provisioning problem for cloud gaming to optimize both server running cost and software maintenance cost. We find that the distribution of game softwares among servers triggers a trade-off between the software maintenance cost and server running cost. We formulate the problem with a stochastic model and employ queueing theories to conduct solid theoretical analysis. We then propose several classes of algorithms to approximate the optimal solution. The proposed algorithms are evaluated by extensive experiments using real-world parameters. The results show that the proposed algorithms are computationally efficient, nearly cost-optimal and highly robust to dynamic changes.","Title: Parallel Algorithm for Single-Source Earliest-Arrival Problem in Temporal Graphs\nYear: 2017\n\nAbstract: Many real-world networks, including online social networks and communication networks, are commonly modeled as temporal graphs. Answering earliest-arrival queries in temporal graphs is one of the most fundamental studies with numerous applications, such as information diffusion and measuring temporal closeness centrality. As graph sizes are growing rapidly, speedup of query execution time becomes even more important.In this paper, we propose a novel edge-centric parallel algorithm for solving single-source earliest-arrival problem in temporal graphs based on a new data structure named Edge-Scan-Dependency Graph (ESD-Graph). We evaluate the proposed parallel algorithm by theoretical analysis as well as by empirical experiments on real-world temporal graphs and synthetic graphs. Empirical results show that the new parallel algorithm outperforms the existing serial algorithm by up to 8.2 and 9.5 times on multi-core processors for real-world data and synthetic data respectively.","Title: Reducing Synchronization Overhead with Computation Replication in Parallel Agent-Based Road Traffic Simulation.\nYear: 2017\n\nAbstract: Road traffic simulation is a useful tool for studying road traffic and evaluating solutions to traffic problems. Large-scale agent-based road traffic simulation is computationally intensive, which triggers the need for conducting parallel simulation. This paper deals with the synchronization problem in parallel agent-based road traffic simulation to reduce the overall simulation execution time. We...","Title: Design And Evaluation Of A Data-Driven Scenario Generation Framework For Game-Based Training\nYear: 2017\n\nAbstract: Generating suitable game scenarios that can cater for individual players has become an emerging challenge in procedural content generation. In this paper, we propose a data-driven scenario generation framework for game-based training. An evolutionary scenario generation process is designed with a fitness evaluation methodology that integrates the processes of AI player modeling, simulation and model training based on artificial neural networks. The fitness function for scenario evaluation can be automatically constructed based on the proposed methodology. To further enhance the evaluation of scenarios, we specifically study the impact of the timing of events in a scenario and propose a generic scenario representation model that characterizes individual scenario based on the types and timing of events in the scenario. We present an extensive evaluation of our framework by validating our AI player model, demonstrating the impact of timing of events in a scenario and comparing the effectiveness of our data-driven framework with our previous heuristic-based approach and a random baseline. The results show that it is necessary to consider the timing of events for scenario evaluation and the proposed framework works well in generating scenarios for game-based training.","Title: Surrogate assisted calibration framework for crowd model calibration\nYear: 2017\n\nAbstract: Surrogate models are commonly used to approximate the multivariate input or output behavior of complex systems. In this paper, surrogate assisted calibration frameworks are proposed to calibrate the crowd model. To integrate the surrogate models into the evolutionary calibration framework, both the offline and online training based approaches are developed. The offline training needs to generate training set in advance, while the online training can adaptively build and re-build the surrogate model along the evolutionary process. Our simulation results demonstrate that the surrogate assisted calibration framework with the online training is effective and the surrogate model using artificial neural network obtains the best overall performance in the scenario evaluated in the case study.","Title: Integration design of supply chain hybrid simulation\nYear: 2017\n\nAbstract: A supply chain (SC) consists of multiple entities representing the retailers, manufacturers, distributors or suppliers. A firm can be one of the entities within the whole SC. To study the external effects on its internal operations, the firm needs to construct a SC model. It may have sufficient data to build a detailed model of its operational processes. However, since it has no control or visibility over the external entities, it is difficult to construct the rest of the SC model at the same level of detail. This paper proposes a hybrid model of the SC using integration design. It allows the whole SC to be captured at the broad view through system dynamics, and the target firm to be represented using agent-based model. The proposed hybrid model is therefore able to capture different behaviors of the same system, e.g, strategic planning of the whole SC, and detailed operational process of individual entities. To demonstrate the applicability of the hybrid model, we evaluate the model through a case study of disruption management policies.","Title: CLUST: Simulating Realistic Crowd Behaviour by Mining Pattern from Crowd Videos.\nYear: 2018\n\nAbstract: In this paper, we present a data-driven approach to simulate realistic locomotion of virtual pedestrians. We focus on simulating low-level pedestrians' motion, where a pedestrian's motion is mainly affected by other pedestrians and static obstacles nearby, and the preferred velocities of agents (direction and speed) are obtained from higher level path planning models. Before the simulation, collision avoidance processes (i.e. examples) are extracted from videos to describe how pedestrians avoid collisions, which are then clustered using hierarchical clustering algorithm with a novel distance function to find similar patterns of pedestrians' collision avoidance behaviours. During the simulation, at each time step, the perceived state of each agent is classified into one cluster using a neural network trained before the simulation. A sequence of velocity vectors, representing the agent's future motion, is selected among the examples corresponding to the chosen cluster. The proposed CLUST model is trained and applied to different real-world datasets to evaluate its generality and effectiveness both qualitatively and quantitatively. The simulation results demonstrate that the proposed model can generate realistic crowd behaviours with comparable computational cost.","Title: Guide them through: An automatic crowd control framework using multi-objective genetic programming.\nYear: 2018\n\nAbstract: •We propose an automatic framework based on genetic programming to generate crowd control strategies.•We propose a Multi-Objective Cartesian Genetic Programming (MO-CGP) algorithm capable of evolving not only parameters but also rule structures so as to find optimal control strategies for multi-objective optimization.•We demonstrate the effectiveness of the framework in a real life crowd control scenario to guide approximately 400 participants to pass through a multi-story building with shorter travel time and reduced congestion at hotspot segments, comparing to several common baseline crowd models.•We propose a rule analysis method through feature selection machine to identify a limited number of most important features in the evolved rules from GP algorithm effectively.","Title: The Server Allocation Problem for Session-Based Multiplayer Cloud Gaming.\nYear: 2018\n\nAbstract: Advances in cloud computing and GPU virtualization are allowing the game industry to move into a cloud gaming era. In this paper, we consider multiplayer cloud gaming (MCG), which is the natural integration of multiplayer online gaming and cloud gaming paradigms. With MCG, a game server and a set of rendering servers for the players need to be located and launched in the clouds for each game sessi...","Title: Fast-Forwarding Agent States to Accelerate Microscopic Traffic Simulations.\nYear: 2018\n\nAbstract: Traditionally, the model time in agent-based simulations is advanced in fixed time steps. However, a purely time-stepped execution is inefficient in situations where the states of individual agents are independent of other agents and thus easily predictable far into the simulated future. In this work, we propose a method to accelerate microscopic traffic simulations based on identifying independence among agent state updates. Instead of iteratively updating an agent's state throughout a sequence of time steps, a computationally inexpensive \"fast-forward\" function advances the agent's state to the time of its earliest possible interaction with other agents. To demonstrate the approach in practice, we present an algorithm to efficiently determine intervals of independence in microscopic traffic simulations and derive a fast-forward function for the popular Intelligent Driver Model (IDM). In contrast to existing acceleration approaches based on reducing the level of model detail, our approach retains the microscopic nature of the simulation. A performance evaluation is performed in a synthetic scenario and on the road network of the city of Singapore. At low traffic densities, we achieved a speedup of up to 2.8, whereas at the highest considered densities, only few opportunities for fast-forwarding could be identified. The algorithm parameters can be tuned to control the overhead of the approach.","Title: Optimize the FP-Tree Based Graph Edge Weight Computation on Multi-core MapReduce Clusters\nYear: 2017\n\nAbstract: The FP-tree based edge weight computation (EWC for short) with MapReduce has demonstrated its remarkable performance for extracting weighted graphs from big data for data analysis. However, our investigation finds that existing algorithm includes unnecessary scan on the datasets as well as unnecessary information for the FP-tree construction, which prolong the runtime execution. In addition, applying inappropriate Reducers-to-cores mapping strategy may make it exhaust the resources and fail to complete the job execution. This paper designs, implements and evaluates an optimized FP-tree based graph EWC algorithm with MapReduce on Multi-core Clusters. First, we design a more compact FP-tree based EWC with 2-phase MapReduce, reducing one phase scan of the dataset. Second, we propose a reduced FP-tree data structure to reduce the FP-tree construction cost. Third, we examine two strategies for mapping Reducers to cores for EWC on each multi-core computer: one-Reducer-one-core and one-Reducer-multiple-cores. Finally, an empirical comparison performance study has been carried out on the optimized EWC algorithm against the existing one over a massive application dataset generated by a real social network. The results demonstrate that the optimized FP-tree based EWC algorithm obtains about 39% to 55% percentage improvement in execution time, and in the meantime achieves better scale-out and scale-up speedup. This paper's findings can also be applied to improve the scalability and efficiency of the parallel and distributed execution of applications involving large scale all-pairs set intersection computation over multi-core MapReduce clusters.","Title: A Survey on Agent-based Simulation using Hardware Accelerators.\nYear: 2019\n\nAbstract: Due to decelerating gains in single-core CPU performance, computationally expensive simulations are increasingly executed on highly parallel hardware platforms. Agent-based simulations, where simulated entities act with a certain degree of autonomy, frequently provide ample opportunities for parallelisation. Thus, a vast variety of approaches proposed in the literature demonstrated considerable performance gains using hardware platforms such as many-core CPUs and GPUs, merged CPU-GPU chips as well as Field Programmable Gate Arrays. Typically, a combination of techniques is required to achieve high performance for a given simulation model, putting substantial burden on modellers. To the best of our knowledge, no systematic overview of techniques for agent-based simulations on hardware accelerators has been given in the literature. To close this gap, we provide an overview and categorisation of the literature according to the applied techniques. Since, at the current state of research, challenges such as the partitioning of a model for execution on heterogeneous hardware are still addressed in a largely manual process, we sketch directions for future research towards automating the hardware mapping and execution. This survey targets modellers seeking an overview of suitable hardware platforms and execution techniques for a specific simulation model, as well as methodology researchers interested in potential research gaps requiring further exploration.","Title: Index Shard Replication Strategies For Improving Resource Utilization In Large Scale Search Engines\nYear: 2018\n\nAbstract: With the rapid growth of the Web scale, large scale search engines have to set up a huge number of machines to place the index files of the Web contents. The index files are normally divided into smaller index shards which are often replicated so that queries can be processed in parallel. We observe that the index shard replication strategy could have a significant impact on the resource utilization of machines. In this paper, we investigate the index shard replication problem with the goal of improving the resource utilization of machines in search engine datacenters. We formulate the problem as a variant of the Multi-Dimensional Vector Bin Packing Problem and propose several strategies to approximate the optimal solution. The proposed strategies are evaluated by extensive experiments using data from real commercial search engines. The results demonstrate the effectiveness of the proposed strategies. Our work also yields many insights about the impact of different input properties on the performance and the key factors that each strategy is sensitive to. We believe that this paper will provide valuable guidance to the choice of the index shard replication strategy in practice.","Title: Cost-Efficient Server Provisioning for Cloud Gaming.\nYear: 2018\n\nAbstract: Cloud gaming has gained significant popularity recently due to many important benefits such as removal of device constraints, instant-on, and cross-platform. The properties of intensive resource demands and dynamic workloads make cloud gaming appropriate to be supported by an elastic cloud platform. Facing a large user population, a fundamental problem is how to provide satisfactory cloud gaming service at modest cost. We observe that the software storage cost could be substantial compared to the server running cost in cloud gaming using elastic cloud resources. Therefore, in this article, we address the server provisioning problem for cloud gaming to optimize both the server running cost and the software storage cost. We find that the distribution of game software among servers and the selection of server types both trigger tradeoffs between the software storage cost and the server running cost in cloud gaming. We formulate the problem with a stochastic model and employ queueing theory to conduct a solid theoretical analysis of the system behaviors under different request dispatching policies. We then propose several classes of algorithms to approximate the optimal solution. The proposed algorithms are evaluated by extensive experiments using real-world parameters. The results show that the proposed Ordered and Genetic algorithms are computationally efficient, nearly cost-optimal, and highly robust to dynamic changes.","Title: A Role-Dependent Data-Driven Approach for High-Density Crowd Behavior Modeling.\nYear: 2018\n\nAbstract: In this article, we propose a role-dependent (RD) data-driven modeling approach to simulate pedestrians’ motion in high-density scenes. It is commonly observed that pedestrians behave quite differently when walking in a dense crowd. Some people explore routes toward their destinations. Meanwhile, some people deliberately follow others, leading to lane formation. Based on these observations, two roles are included in the proposed model: leader and follower. The motion behaviors of leader and follower are modeled separately. Leaders’ behaviors are learned from real crowd motion data using state-action pairs, while followers’ behaviors are calculated based on specific targets that are obtained dynamically during the simulation. The proposed RD model is trained and applied to different real-world datasets to evaluate its generality and effectiveness. The simulation results demonstrate that the RD model is capable of simulating crowd behaviors in crowded scenes realistically and reproducing collective crowd behaviors such as lane formation.","Title: Optimizing Agent-Based Simulations for the GPU\nYear: 2018\n\nAbstract: Agent-based simulation (ABS) is a powerful tool to analyze the behavior of agents interacting with each other. Many simulations contain a large number of agents or re¬quire multiple executions with different parameters, making the simulation-based experimentation slow. In recent years, graphics processing units (GPUs) have proven to be a powerful platform for accelerating ABS. In this paper, we propose several novel techniques to further improve the efficiency of GPU-based ABS. Our techniques reduce the total amount of computation in ABS, improve memory access patterns, and exploit temporal locality to minimize redundant calculations. Furthermore, the optimizations can be implemented as a layer on top of existing simulators, as we demonstrate by modifying the popular GPU-based simulator FLAME. We perform experiments using the Boids and Social Force simulations, and show that our techniques improve overall performance by up to 3.2× and 2.1× respectively compared to the original FLAME.","Title: Exploring Execution Schemes for Agent-Based Traffic Simulation on Heterogeneous Hardware.\nYear: 2018\n\nAbstract: Microscopic traffic simulation is associated with substantial runtimes, limiting the feasibility of large-scale evaluation of traffic scenarios. Even though today heterogeneous hardware comprised of CPUs, graphics processing units (GPUs) and fused CPU-GPU devices is inexpensive and widely available, common traffic simulators still rely purely on CPU-based execution, leaving substantial acceleration potentials untapped. A number of existing works have considered the execution of traffic simulations on accelerators, but have relied on simplified models of road networks and driver behaviour tailored to the given hardware platform. Thus, the existing approaches cannot directly benefit from the vast body of research on the validity of common traffic simulation models. In this paper, we explore the performance gains achievable through the use of heterogeneous hardware when relying on typical traffic simulation models used in CPU-based simulators. We propose a partial offloading approach that relies either on a dedicated GPU or a fused CPU-GPU device. Further, we present a traffic simulation running fully on a many-core GPU and discuss the challenges of this approach. Our results show that a CPU-based parallelisation closely approaches the results of partial offloading, while full offloading substantially outperforms the other approaches. We achieve a speedup of up to 28.7x over the sequential execution on a CPU.","Title: Incremental calibration of Seat Selection Preferences in Agent-based simulations of Public transport Scenarios.\nYear: 2018\n\nAbstract: The calibration of agent-based pedestrian simulation models requires empirical data. To avoid cost-intensive real-world experiments, human-in-the-loop simulations can be applied in which simulated pedestrians interact with human-controlled agents. However, the experiment results may be unrealistic if the human participants are presented with agents acting according to an uncalibrated model. We propose an incremental calibration approach that aims to address the circular dependency between the behaviour of human and simulated pedestrians. By incrementally adapting the parameters of the simulated agents to match the behaviour of the human participants, we aim to gradually approach a realistic interaction. We evaluate our approach using the simulation of the boarding procedure of a public transport vehicle in 2D and virtual reality experiments. The calibration results are compared with those gathered from a traditional non-incremental calibration. Our results indicate the feasibility of our approach and highlight the necessity for future research on efficient simulation model calibration.","Title: Model Preemption based on Dynamic Analysis of simulation Data to Accelerate Traffic light Timing optimisation.\nYear: 2018\n\nAbstract: Since simulation-based optimisation typically requires large numbers of runs to identify sufficiently good solutions, the costs in terms of time and hardware can be enormous. To avoid unnecessary simulation runs, surrogate models can be applied, which estimate the simulation output under a given parameter combination. Model preemption is a related technique that dynamically analyses the simulation state at runtime to identify runs unlikely to result in a high-quality solution and terminates such runs early. However, existing work on model preemption relies on model-specific termination rules. In this paper, we describe an architecture for simulation-based optimisation using model preemption based on estimations of the simulation output. In a case study, the approach is applied to the optimisation of traffic light timings in a traffic simulation. We show that within a given time and hardware budget, model preemption enables the identification of higher-quality solutions than those found through traditional simulation-based optimisation.","Title: Dynamic Data Driven Application Systems - Research Challenges and Opportunities.\nYear: 2018\n\nAbstract: Dynamic Data Driven Applications Systems (DDDAS) is a paradigm where data is dynamically integrated into an executing application, and in reverse, the application dynamically steers the measurement process in a feedback control loop. Since its inception in 2000, the DDDAS concept has been successfully applied to a host of application areas. New technologies are emerging such as big data, the Internet of Things, and cloud/edge computing. With these trends DDDAS is poised to have large-scale impacts in areas such as smart cities, manufacturing, health care, and security, to name a few. Each author describes their views concerning the important research challenges facing the DDDAS paradigm and opportunities for impact in the years ahead.","Title: Concurrent Hybrid Breadth-First-Search on Distributed PowerGraph for Skewed Graphs\nYear: 2018\n\nAbstract: Large-scale graph-structured computation is becoming increasingly important for various data analytics applications. However, most distributed graph processing frameworks do not directly support efficient implementation of sophisticated algorithms requiring massive graph traversals. In this paper, we propose concurrent hybrid breadth-first-search (BFS) algorithm on a popular distributed graph processing framework (Power-Graph and its optimized version PowerLyra). It leverages the small-world property of skewed graphs which apply to most realworld data sets. Hybrid BFS algorithm changes graph traversal direction to save computational workload and message transmissions. Concurrent BFS algorithm enables running multiple BFS simultaneously while sharing vertex explorations efficiently with bit operations. Extensive experiments are conducted to evaluate performance and scalability on a multi-core computer and a cluster of AWS instances. Concurrent hybrid BFS algorithm dramatically increases graph traversal efficiency with respect to the increasing number of concurrent BFS traversals. Compared with PowerGraph, PowerLyra uses fewer resources, while achieving significantly higher performance and better scalability.","Title: Key Message Approach to Optimize Communication of Parallel Applications on Clusters\nYear: 2003\n\nAbstract: Over the past few years, cluster/distributed computing has been gaining popularity. The proliferation of the cluster/distributed computing is due to the improved performance and increased reliability of these systems. Many parallel programming languages and related parallel programming models have become widely accepted. However, one of the major shortcomings of running parallel applications on cluster/distributed computing environments is the high communication overhead incurred. To reduce the communication overhead, and thus the completion time of a parallel application, this paper describes a simple, efficient and portable Key Message (KM) approach to support parallel computing on cluster/distributed computing environments. To demonstrate the advantage of the KM approach, a prototype runtime system has been implemented and evaluated. Our preliminary experimental results show that the KM approach has better improvement on communication of a parallel application when network background load increases or the computation to communication ratio of the application decreases.","Title: Managing irregular workloads of cooperatively shared computing clusters\nYear: 2004\n\nAbstract: Cooperative resource sharing enables distinct organizations to form a federation of computing resources. A functional broker is deployed to facilitate remote resource access within the community grid. A major issue is the problem of correlations in job arrivals caused by seasonal usage and/or coincident resource usage demand patterns where high levels of burstiness in job arrivals can cause the job queue of the broker to grow to an extent such that its performance becomes severely impaired. Since job arrivals cannot be controlled, management strategies must be employed to admit jobs to sustain the resource allocation performance of the broker. In this paper, we present a theoretical analysis of the problem of job traffic burstiness on resource allocation performance in order to elicit the general job management strategies to be employed. Based on the analysis, we define and justify a job management framework for the resource broker to cope with overload conditions caused by job arrival correlations.","Title: Efficient Parallel Simulation over Social Contact Network with Skewed Degree Distribution.\nYear: 2017\n\nAbstract: Social contact network (SCN) models the contacts between people by their daily activities. It can be formalized by an agent-to-location bipartite graph. The simulations over SCN are employed to study the complex social dynamics such as information propagation and disease spread among large-scale population. A challenge to the simulation is the skewed degree distribution of SCN, which contains a few hub locations with large numbers of visitors. The skewed degree distribution can cause load imbalance for parallel simulation and greatly degrade the execution performance. This paper proposes an approach which decomposes hub locations into small splits. Thus, SCN can be partitioned with better balanced workloads and multiple splits are able to run in parallel. Based on the pattern of information transmission between agents, we duplicate necessary data among splits to ensure the correctness of simulation. Furthermore, we enhance the parallel algorithm of SCN simulation to reduce the additional overhead from communication between splits. Finally, we build an experiment with epidemic simulation on an open dataset. The experimental results demonstrate that our approach achieves 14~35% performance improvement compared with the partitioning method without decomposition of hub locations.","Title: Evaluation of Conflict Resolution Methods for Agent-Based Simulations on the GPU.\nYear: 2018\n\nAbstract: Graphics processing units (GPUs) have been shown to be well-suited to accelerate agent-based simulations. A fundamental challenge in agent-based simulations is the resolution of conflicts arising when agents compete for simulated resources, which may introduce substantial overhead. A variety of conflict resolution methods on the GPU have been proposed in the literature. In this paper, we systematize and compare these methods and propose two simple new variants. We present performance measurements on the example of the well-known segregation model. We show that the choice of conflict resolution method can substantially affect the simulation performance. Further, although methods in which agents actively indicate their interest in a resource require the use of costly atomic operations, these methods generally outperform the alternatives.","Title: A Graph-Based Model To Measure Structural Redundancy For Supply Chain Resilience\nYear: 2019\n\nAbstract: Globalisation and lean initiatives increase the vulnerabilities of the supply chains (SC), where disruptions in any plant in a supply chain network (SCN) can propagate throughout the whole SCN. Redundancy is part of the SC re-engineering to improve supply chain resilience (SCRES). This paper presents a conceptual model of an SCN using graph theory, considering the relationships between plants and materials. Based on the model, the structural redundancy of the SCN is measured, which is used to assess SCRES. This assessment approach focuses on the resilience of the SCN against disruptions. Case studies are discussed to illustrate the applicability of this model and show that increasing structural redundancy of the SCN improves SCRES against disruptions.","Title: Efficient Parallel Simulation over Large-scale Social Contact Networks\nYear: 2019\n\nAbstract: Social contact network (SCN) models the daily contacts between people in real life. It consists of agents and locations. When agents visit a location at the same time, the social interactions can be established among them. Simulations over SCN have been employed to study social dynamics such as disease spread among population. Because of the scale of SCN and the execution time requirement, the simulations are usually run in parallel. However, a challenge to the parallel simulation is that the structure of SCN is naturally skewed with a few hub locations that have far more visitors than others. These hub locations can cause load imbalance and heavy communication between partitions, which therefore impact the simulation performance. This article proposes a comprehensive solution to address this challenge. First, the hub locations are decomposed into small locations, so that SCN can be divided into partitions with better balanced workloads. Second, the agents are decomposed to exploit data locality, so that the overall communication across partitions can be greatly reduced. Third, two enhanced execution mechanisms are designed for locations and agents, respectively, to improve simulation parallelism. To evaluate the efficiency of the proposed solution, an epidemic simulation was developed and extensive experiments were conducted on two computer clusters using three SCN datasets with different scales. The results demonstrate that our approach can significantly improve the execution performance of the simulation.","Title: A Data-driven Path Planning Model for Crowd Capacity Analysis\nYear: 2019\n\nAbstract: •Developed a data-driven pedestrian origin-destination and route choice model by learning from video data.•The data-driven model can be used for capacity analysis of the building layout.•Enhanced the route choice model by taking into account the crowd density in the building layout on route choice.•Developed the crowd density aware route choice model through virtual reality experiments and Support Vector Classification.","Title: From Effects to Causes: Reversible Simulation and Reverse Exploration of Microscopic Traffic Models.\nYear: 2019\n\nAbstract: We propose an approach for reverse-in-time exploration of the state space of microscopic traffic simulations starting from a user-specified class of outcomes. As a basis for our approach, we present a reversible execution scheme applicable to common car-following and lane-changing models from the traffic simulation literature. The execution scheme permits perfect reversal of a previous forward simulation, which to our knowledge has not been attempted previously in the context of established traffic simulation models. Further, we perform reverse state space explorations directly from user-specified simulation states, i.e., reverse-in-time model checking. By exploring all sequences of possible previous states from a final state, reachability questions can be answered more conclusively than purely through forward simulations. In a case study, reverse exploration is used to identify conditions that lead to specified accident situations, with running time reductions by factors of more than 20 compared to traditional forward exploration.","Title: Transitioning Spiking Neural Network Simulators to Heterogeneous Hardware.\nYear: 2019\n\nAbstract: Spiking neural networks (SNN) are among the most computationally intensive types of simulation models, with node counts on the order of up to 10^11. Currently, there is intensive research into hardware platforms suitable to support large-scale SNN simulations, whereas several of the most widely used simulators still rely purely on the execution on CPUs. Enabling the execution of these established simulators on heterogeneous hardware allows new studies to exploit the many-core hardware prevalent in modern supercomputing environments, while still being able to reproduce and compare with results from a vast body of existing literature. In this paper, we propose a transition approach for CPU-based SNN simulators to enable the execution on heterogeneous hardware (e.g., CPUs, GPUs, and FPGAs) with only limited modifications to an existing simulator code base, and without changes to model code. Our approach relies on manual porting of a small number of core simulator functionalities as found in common SNN simulators, whereas unmodified model code is analyzed and transformed automatically. We apply our approach to the well-known simulator NEST and make a version executable on heterogeneous hardware available to the community. Our measurements show that at full utilization, a single GPU achieves the performance of about 9 CPU cores.","Title: GAugur: Quantifying Performance Interference of Colocated Games for Improving Resource Utilization in Cloud Gaming\nYear: 2019\n\nAbstract: Cloud gaming has been very popular recently, but providing satisfactory gaming experiences to players at a modest cost is still challenging. Colocating several games onto one server could improve server utilization. To enable efficient colocations while providing Quality of Service (QoS) guarantees, a precise quantification of performance interference among colocated games is required. However, achieving such precise interference prediction is very challenging for games due to the complexity introduced by the contention on many shared resources across CPU and GPU. Moreover, the distinctive properties of cloud gaming require that the prediction model should be constructed beforehand and the prediction should be made instantaneously at request arrivals, which further increases the difficulty. The existing solutions are either not applicable or not effective due to many limitations. In this paper, we present GAugur, a novel methodology that enables highly accurate prediction of the performance interference among games arbitrarily colocated. By leveraging machine learning technologies, GAugur is able to capture the complex relationship between the interference and the contention features of colocated games. We evaluate GAugur through extensive experiments using a large number of real popular games. The results show that GAugur is able to identify whether a colocated game satisfies QoS requirement within an average error of 5%, and is able to quantify the performance degradation of a colocated game within an average error of 7.9%, which significantly outperforms the alternatives. Moreover, GAugur incurs an offline profiling cost linear to the number of games, and negligible overhead for online prediction. We apply GAugur to guiding efficient game colocations for cloud gaming. Experimental results show that GAugur is able to increase the resource utilization by 20% to 60%, and improve the overall performance by up to 15%, compared to the state-of-the-art solutions.","Title: An Agent-Based Model For Evaluating The Boarding And Alighting Efficiency Of Autonomous Public Transport Vehicles\nYear: 2019\n\nAbstract: A key metric in the design of interior layouts of public transport vehicles is the dwell time required to allow passengers to board and alight. Real-world experimentation using physical vehicle mock-ups and involving human participants can be performed to compare dwell times among vehicle designs. However, the associated costs limit such experiments to small numbers of trials. In this paper, we propose an agent-based simulation model of the behavior of passengers during boarding and alighting. High-level strategical behavior is modeled according to the Recognition-Primed Decision paradigm, while the low-level collision-avoidance behavior relies on an extended Social Force Model tailored to our scenario. To enable successful navigation within the confined space of the vehicle, we propose a mechanism to emulate passenger turning while avoiding complex geometric computations. We validate our model against real-world experiments from the literature, demonstrating deviations of less than 11%. In a case study, we evaluate the boarding and alighting times required by three autonomous vehicle interior layouts proposed by industrial designers.","Title: A New Double Rank-based Multi-workflow Scheduling with Multi-objective Optimization in Cloud Environments\nYear: 2021\n\nAbstract: Workflow scheduling in clouds has been extensively researched. Many workflows from different users could be submitted to clouds at the same time and cloud providers should handle them simultaneously. So, it is necessary to consider the problem of scheduling multi-workflow. In addition, cloud computing systems can offer some special features, like Pay-Per-Use and Quality of Service (QoS) over the I...","Title: Data-driven Microscopic Traffic Modelling and Simulation using Dynamic LSTM\nYear: 2021\n\nAbstract: ABSTRACTWith the increasing popularity of Digital Twin, there is an opportunity to employ deep learning models in symbiotic simulation system. Symbiotic simulation can replicate multiple what-if simulation instances from its real-time reference simulation (base simulation) for short-term forecasting. Hence, it is a useful tool for just-in-time decision making process. Recent trends on symbiotic simulation studies emphasize on its combination with machine learning. Despite its success and usefulness, very few works focus on application of such a hybrid system in microscopic traffic simulation. Existing application of machine (deep) learning models in microscopic traffic simulation is confined to either predictive analysis or offline simulation-based prescriptive analysis. Thus, there is also lack of work on updating parameters of a deep learning model dynamically for real-time traffic simulation. This is necessary if the learning-based model is to be used as part of the base simulation so that \"Just-in-time (JIT)\" what-if simulation initialized from the model can make better short-term forecasts. This paper proposes a data-driven modelling and simulation framework to dynamically update parameters of Long Short-term Memory (LSTM) for JIT microscopic traffic simulation. Extensive experiments were carried out to demonstrate its effectiveness in terms of more accurate short-term forecasting than other baseline models.","Title: Causality and Consistency of State Update Schemes in Synchronous Agent-based Simulations\nYear: 2021\n\nAbstract: ABSTRACTIn an agent-based simulation (ABS), a state update scheme carries out the transitions of agents from one state to the next. To produce correct simulation results, the update scheme must respect the cause-and-effect relationships defined by the agent-based model and ensure that the resulting overall simulation state is internally consistent. At the same time, the update scheme should be efficient enough to meet a simulationist's demand for timely results. Considering the common class of synchronous time-driven ABS, a number of update schemes have been employed in the literature and simulation frameworks. In this paper, various implementations of update schemes are analyzed and contrasted with respect to their ability to maintain the simulation correctness as well as their performance characteristics. A semantic model is formulated to define the reference behavior of synchronous time-driven ABS updates and model the dependencies among agent updates using a state access graph. Relying on the formalization, conditions under which different update schemes achieve causality are shown. Further, resolution methods are categorized according to their coordination mechanisms to achieve consistency by resolving conflicts among agent state updates. Through two case studies, the empirical performance of different update schemes and resolution methods are evaluated. For sequential execution, an update scheme based on the agent's dependencies achieves the highest performance, whereas in the parallel case, the choice of update scheme involves a tradeoff between execution time and memory usage. If deterministic simulation output is required, decentralized coordination generally outperforms centralized coordination. The results can assist implementers and researchers in their selection of appropriate methods in the design and implementation of agent-based simulators.","Title: A Parallel Hierarchical Sort-based Interest Matching Algorithm\nYear: 2021\n\nAbstract: ABSTRACTInterest management is a filtering technique to reduce communication in simulation. It involves a process called \"interest matching\" to identify intersections between two sets of d-dimensional axis-parallel rectangles. Because of frequent demands in simulation execution, interest matching becomes a bottleneck as the problem size grows. However, classical interest matching algorithms, mainly designed for serial processing, do not take advantage of modern multicore processors' computing power. Recent parallel interest matching algorithms can fill the gap, but there is scope for improvement. In this paper, we propose a parallel hierarchical sort-based interest matching algorithm. It embeds subscription regions into an interest management tree and allows update regions compare with nodes of the tree to find results in parallel. The association between adjacent nodes and the hierarchical relation between parent-child nodes can serve to eliminate unnecessary operations. Moreover, we also provide proof to confirm the correctness and a detailed analysis of time-complexity. The experimental results demonstrate that the proposed algorithm can achieve better performance than state-of-art algorithms.","Title: Hot Area Targeting Dead Reckoning for Distributed Virtual Environments\nYear: 2021\n\nAbstract: ABSTRACTDead reckoning (DR) is a key technique to increase scalability in Distributed Virtual Environments (DVE). Replacing data transmission with prediction, DR relies on its prediction capability to reduce the bandwidth consumption in the cost of inconsistency among participants. We propose a hot area targeting DR (HATDR) approach to increase the prediction capability by the hot area targeting pattern discovered with a noise-resistant clustering approach. This approach is shown to be robust against hyperparameters. Experiments carried out with a real-life MMOG dataset show that HATDR is comparable to the state-of-the-art DR approaches.","Title: Data-driven Crowd Modeling Techniques: A Survey\nYear: 2022\n\nAbstract: AbstractData-driven crowd modeling has now become a popular and effective approach for generating realistic crowd simulation and has been applied to a range of applications, such as anomaly detection and game design. In the past decades, a number of data-driven crowd modeling techniques have been proposed, providing many options for people to generate virtual crowd simulation. This article provides a comprehensive survey of these state-of-the-art data-driven modeling techniques. We first describe the commonly used datasets for crowd modeling. Then, we categorize and discuss the state-of-the-art data-driven crowd modeling methods. After that, data-driven crowd model validation techniques are discussed. Finally, six promising future research topics of data-driven crowd modeling are discussed.","Title: E 2 T-CVL: An Efficient and Error-Tolerant Approach for Collaborative Vehicle Localization\nYear: 2022\n\nAbstract: The proliferation of vehicle-to-vehicle (V2V) communication techniques has resulted in collaborative vehicle localization (CVL) approaches that localize a target vehicle by leveraging the state information of nearby vehicles. However, CVL approaches typically require a large search space to locate the real position of a target vehicle and assume small measurement errors of nearby vehicle informati...","Title: Research on the collaboration of service selection and resource scheduling for IoT simulation workflows\nYear: 2022\n\nAbstract: Cloud resources provide a promising way to efficiently perform the needed simulation tasks for a complex manufacturing process. Most of the existing work focuses only on how to effectively schedule computing resources to execute computing requirements of simulation workflows in Internet of Things (IoT) applications. Research on the scheduling of simulation workflows in consideration of task ordering, service selection, and resource allocation altogether has not been lacking. To fill in this void, this paper proposes a cloud-based 3-stage workflow scheduling model. Before scheduling computing resources to complete task requirements, the order of the tasks is determined and the services that can meet the task requirements are selected. In this model, the workload to satisfy task requirements is not fixed and takes on a different value depending upon the service selected with its unique complexity and accuracy. An optimization function that transforms and integrates makespan, cost, and accuracy in a unique way is proposed. For its solution, the relatively new symbiotic organisms search (SOS) algorithm is modified and two SOS-based optimization strategies are developed, i.e., joint optimization-based SOS (JOSOS) and split optimization-based SOS (SOSOS). The simulation results reveal that SOS-based algorithms, especially the SOSOS method, outperform all compared algorithms. Based on the proposed method, simulation services and computing resources can be rationally selected and scheduled to ensure the requirements of IoT applications.","Title: A wholistic optimization of containerized workflow scheduling and deployment in the cloud–edge environment\nYear: 2022\n\nAbstract: Digital Twin in Industry 4.0 utilizes Internet of Things (IoT) to collect real-life data and combine it with simulation models for product design and development. The simulation process can be executed as a workflow, consisting of tasks with precedence constraints. In a container-based workflow execution system, each task in the workflow is executed in a container within a virtual machine (VM). In this paper, a three-step scheduling model is proposed to combine scheduling of container-based workflows and the deployment of containers on a cloud–edge environment. In the first step, virtual CPU (vCPU) is allocated for each container to enable vCPU sharing among different containers. Next, two-step resource deployment is used to schedule the containers onto VM, and VM onto the physical machines in either edge or cloud environment. Multiple objectives are considered, including minimizing makespan, load imbalance, and energy consumption, from the perspective of cloud–edge resources as well as containerized workflows. To obtain a set of non-dominated solutions, three evolution strategies are designed and combined with two multi-objective algorithm frameworks — co-evolution strategy (CES), basic non-co-evolution strategy (B-NCS), and hybrid non-co-evolution strategy (H-NCS). Simulation results demonstrate that the proposed model outperforms the existing two-step scheduling model and H-NCS performs better than other strategies.","Title: Distribution-Based Weights Estimation for Map Matching Algorithms\nYear: 2022\n\nAbstract: With the development of mobile computing, map matching algorithms are utilized to recover vehicles’ traveling routes. Existing map matching algorithms usually infer the traveling routes based on a driving cost model that considers various traveling features and driving preferences (referred to as weights). In general, the weights are estimated either empirically or through data-driven approaches. For empirical setting, the weights are determined based on field studies and must be reestimated when the driving scenarios are changed. Alternatively, in data-driven approaches, the weights are determined from the analysis of historical routes of vehicles. However, estimation bias may be introduced due to the selection of data sources. To decrease the estimation bias, this article proposes a distribution-based weights estimation method. Specifically, the weights are estimated by inferring their distributions through Bayesian inference based on the driver traces collected in a city scale. Next, a sampling-based strategy is adopted to determine the weights values from their distributions. Experimental results show that the proposed approach achieves a higher map matching accuracy than the existing approaches, and it is applicable for both linear and nonlinear driving cost models used in map matching algorithms. Moreover, the estimated weights can help to understand driver preferences in different traveling cases.","Title: SPIDER: An Effective, Efficient and Robust Load Scheduler for Real-time Split Frame Rendering\nYear: 2022\n\nAbstract: Interactive graphics applications are generally latency-critical, while using multiple GPUs to accelerate such applications becomes possible recently with support from both hardware and software. Split frame rendering (SFR) is a popular approach for multi-GPU rendering, which splits a frame into disjoint regions and assigns the regions to different GPUs. Load scheduling of SFR is a crucial but challenging issue for achieving maximum rendering performance in real-time rendering, which is not well addressed by the existing solutions. In this paper, we propose SPIDER, a load scheduler which leverages fuzzy PID (proportional integral derivative) controller to schedule the rendering workload among GPUs. SPIDER has several distinguished properties: it is a feedback based mechanism which does not need a full knowledge of the dynamic system; it is very computationally efficient and easy to implement; it is highly robust to dynamic workload changes. Extensive experiments are conducted to evaluate SPIDER and the results show that SPIDER always achieves near-optimal performance for various workload patterns, which outperforms the state-of-the-art baselines signif-icantly.","Title: Improving Scalability, Sustainability and Availability via Workload Distribution in Edge-Cloud Gaming\nYear: 2022\n\nAbstract: ABSTRACTRecent uses of heterogeneous mobile and lightweight devices encourage computations to be abstracted remotely as black box systems. This same concept applies for cloud gaming in which computer games are located and run inside remote rendering servers (RSes). While cloud gaming enables lightweight devices with sufficient input capabilities and network connection to be able to play desktop games, latency and cost issue become significant hindrances in recent applications. In this paper, we came up with our edge-cloud gaming architecture which reduces the overall workload in RSes while increasing playerbase coverage by using edge RSes. Furthermore, we also proposed our allocation algorithm in order to assign incoming players to RSes. From our experiments, our proposed architecture has higher playerbase coverage while our allocation algorithm significantly reduces the cost in both single and batch player arrival pattern."],"string":"[\n \"Title: File allocation with balanced response time in a distributed multi-server information system\\nYear: 1998\\n\\nAbstract: As information systems move from centralized to distributed systems, the distribution of the data files among the servers becomes a major issue. This paper reports on the results of a heuristic algorithm that is used to distribute the files among multiple heterogeneous servers interconnected by a fast network. The objective of our algorithm is to minimize the differences between response times of the servers (or in other words, to minimize the response imbalance factor). The servers are modeled using M/M/1 queues. In this paper, we first describe the problem, then the algorithm is presented and its bounds on the imbalance factor analyzed. The characteristics of our algorithm are also studied through simulation. Results are compared with the algorithms proposed by other researchers, which show a considerable improvement in the imbalance factor and only a slight increase in the average response time of the system.\",\n \"Title: A secure information service for monitoring large scale grids\\nYear: 2007\\n\\nAbstract: The Grid Information Service (GIS) is a core component in the Grid software infrastructure. It provides diverse information to users or other service components in Grid environments. In this paper, we propose a scalable GIS architecture for information management in a large scale Grid Virtual Organization (VO). This architecture consists of the VO layer, site layer and resource layer: at the resource layer, information agents and pluggable information sensors are deployed on each resource monitored. This information agent and sensor approach provides a flexible framework that enables specific information to be captured; at the site layer, a site information service component with caching capability aggregates and maintains up-to-date information of all the resources monitored within an administrative domain; at the VO layer, a peer-to-peer approach is used to build a virtual network of site information services for information discovery and query in a large scale Grid VO. This decentralized approach makes information management scalable and robust. Furthermore, we propose a security framework for the GIS, which provide security policies for authentication and authorization control of the GIS at both the site and the VO layers. Our GIS has been implemented based on the Globus Toolkit 4 as Web services compliant to Web Services Resource Framework (WSRF) specifications. The experimental results show that the GIS presents satisfactory scalability in handling information for large scale Grids.\",\n \"Title: A utility model for timely state update in distributed wargame simulations\\nYear: 2004\\n\\nAbstract: In distributed wargame simulations, the states of simulation entities need to be updated and sent to other simulation nodes in a timely manner, which may incur high overhead on the network. Thus, how to efficiently use the limited bandwidth of the network is very important to the performance of distributed wargame simulations. In this paper, a utility model is proposed to evaluate the relative importance of a simulation entity. In our proposed utility model, the utility of an entity is determined by the number of entities on which this entity may have influence and the distances between this entity and the entities within its area of influence. Based on the utility model, we may devise some flexible updating mechanisms which can utilize the bandwidth more efficiently. For example, the state updates of an important entity which may have nodes with a high frequency; on the other hand, the state updates of an entity with little importance may be sent to other simulation nodes with a low frequency. In this paper, we will focus on the utility computation of a simulation entity rather than the flexible state updating mechaisms for the simulation entities. Our proposed utility computation mechanism is general and can be easily implemented using the HLA services. Experimental results show that the utility computation mechanism incurs little overhead.\",\n \"Title: GPU accelerated three-stage execution model for event-parallel simulation.\\nYear: 2013\\n\\nAbstract: This paper introduces the concept of event-parallel discrete event simulation (DES) and its corresponding implementation on the GPU platform. Inspired by the typical spatial-parallel DES and time-parallel DES, the event-parallel approach on GPU uses each thread to process one of the N events, where N is the total number of events. By taking advantage of the high parallelism of GPU threads, this approach achieves greater speedup. The GPU architecture is adopted in the execution of the event-parallel approach, so as to take advantage of the parallel processing capability provided by the massively large number of GPU threads. A three-stage execution model composing of generating events, sorting events and processing events in parallel is proposed. This execution model achieves good speedup. Compared with the event scheduling approach on CPU, we achieve up to 22.80 speedup in our case study.\",\n \"Title: SOAr-DSGrid: Service-Oriented Architecture for Distributed Simulation on the Grid\\nYear: 2006\\n\\nAbstract: Simulation is a low cost alternative to experimentation on real-world physical systems. Grid technology enables coordinated use of and secure access to distributed computing resources and data sources. The service-oriented architecture (SOA) is an ideal paradigm for next generation computing. The loose coupling among services in the SOA relieves service consumers from detailed knowledge of implementation, implementation language, and execution platform of the services to be consumed. In this paper, we propose a framework for developing a component-based distributed simulation and executing the simulation in a service-oriented architecture on the Grid. This framework consists of the schemas for developing simulation components and simulation applications, and underlying base component service modules for constructing a simulation component as a service. The use of component interfaces and schemas enables collaborative development of simulation applications, and the deployment of simulation components as services takes advantage of the SOA (e.g., loose coupling, heterogeneity, and transport neutrality). This paper discusses the motivation for developing such a framework and describes the details of its development.\",\n \"Title: Update schedules for improving consistency in multi-server distributed virtual environments.\\nYear: 2014\\n\\nAbstract: Distributed Virtual Environments (DVEs) have been widely used in online games, military training and collaborative engineering applications, etc. In DVEs, the primary task is to maintain a consistent view of the virtual world among all users. Multi-server architecture has been shown to have good scalability to support a large population of users in DVEs. However, servers can still get saturated with network bandwidth due to several reasons. In this case, state updates cannot be disseminated timely and the consistency of the virtual world cannot be guaranteed. This paper investigates update schedules to prioritize state updates from a global perspective for improving consistency in multi-server DVEs where each server has a limit on upload bandwidth. Using time–space inconsistency (TSI) metric, we analyze the problem using Lagrange Multipliers for a DVE in an ideal situation with unchanged configurations and the results are then used to develop an updating algorithm in practical systems. Experimental results show that the proposed algorithm significantly improves the consistency compared to other existing update algorithms.\",\n \"Title: A framework for executing parallel simulation using RTI\\nYear: 2003\\n\\nAbstract: The grid enables large-scale resource sharing and makes it viable for running large-scale parallel and distributed simulations. The high level architecture (HLA) paradigm provides a software platform and interoperability interface for simulation components to utilize these hardware resources. However, neither the grid nor the HLA provides mechanism for resource management for parallel and distributed simulations. It is also noticed that substantial effort is required for writing program that conforms to the runtime infrastructure (RTI) requirements because of its complexity. In this paper, we introduce a framework for designing and executing parallel simulation using the RTI. The framework is also designed to assist load balancing and checkpointing. With the code library from our framework, the modeler is able to complete the design of a parallel simulation that runs on RTI by specifying the simulation configuration and the handling detail of each event. Our framework incorporates automatic code generation. It also uses data distribution management (DDM) to route simulation events (interactions) to achieve efficient use of network bandwidth.\",\n \"Title: Design and implementation of an efficient multi-cluster GridRPC system\\nYear: 2005\\n\\nAbstract: Multi-cluster Grids have emerged as the most popular type of grid environments. On multi-cluster grid, resources are distributed across different networks. Hence, scheduling and dispatching jobs are difficult and inefficient due to the restrictions of network and the communication overhead. This paper presents the design and implementation of an efficient GridRPC system for the multi-cluster grid. Metascheduling mechanism is developed to distribute jobs onto different clusters of computers effectively. Further, a dynamic bundling mechanism is provided to reduce overhead of job dispatching. This mechanism bundles similar requests to form a composite request that is dispatched to a grid resource. The above mechanisms have been tested with different types of services and loads, and the results show that they help to achieve more balanced workload and reduce the overhead of job dispatching. This cuts down execution time of applications.\",\n \"Title: HLA-Based Distributed Simulation Cloning\\nYear: 2004\\n\\nAbstract: Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same simulation execution session. One important goal of the technology is to optimize execution by avoiding repeated computation amongst independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA) based distributed simulations. A decoupled federate architecture is designed to support correct federate cloning at runtime. A federate may spawn clones to explore different scenarios at a decision point. To address the complexity of the overall cloning-enabled distributed simulation due to increasing scenario spawning, we have devised an efficient and precise scheme to identify and partition scenarios. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected while the rest remain intact and are shared amongst the original and new scenarios. Our incremental cloning mechanism ensures accurate sharing and initiates cloning only when strictly necessary.\",\n \"Title: Algorithms for HLA-based distributed simulation cloning\\nYear: 2005\\n\\nAbstract: Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same execution session. One important goal is to optimize execution by avoiding repeated computation among independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA)-based distributed simulations; a federate may spawn clones to explore different scenarios at a decision point. This article introduces the cloning mechanism and the supporting infrastructure. When enabling cloning, our approach ensures the state consistency and supports user transparency and reusability of federate codes. When a federate clones, it is desirable to replicate only those federates whose states will be affected while the rest are shared among the old and new scenarios. This article discusses the theory and issues involved in such an incremental cloning mechanism, which guarantees accurate sharing and initiates cloning only when absolutely necessary. Experiments have been carried out to compare the performance of entire cloning and incremental cloning mechanisms. Experimental results indicate that the proposed approach provides correct cloning and can significantly reduce the execution time for evaluating different scenarios of a distributed simulation. Moreover the incremental cloning mechanism significantly surpasses entire cloning in terms of execution efficiency.\",\n \"Title: A prototype of distributed molecular visualization on computational grids\\nYear: 2004\\n\\nAbstract: The architecture and the computational kernels of Simulation of Crossed Molecular Beam Experiments, an Internet portal managing the simulation of elementary bimolecular processes as those occurring in crossed beam apparatuses, is discussed. The construction ...\",\n \"Title: Collaborative Interest Management for Peer-to-Peer Networked Virtual Environment\\nYear: 2011\\n\\nAbstract: Interest Management (IM) aims at eliminating irrelevant state updates transmitted in Networked Virtual Environment (NVE). The traditional IM mechanisms can be classified into area-based and cell-based mechanisms. Hybrid IM mechanism was proposed recently to reduce the communication overhead by utilizing the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism. Compared to the traditional mechanisms, the hybrid mechanism reduces the upload bandwidth consumption at each player site and thus allows more players to join the virtual environment with today's network capacity. However, it requires each player maintains some global information about all other players. Updating the global information undoubtedly involves communication overhead. This paper proposes a collaborative IM mechanism for peer-to-peer NVEs, which works only relying on each joining player's local knowledge rather than globally available information so as to further reduce the communication cost of IM mechanisms. The performance of our collaborative IM mechanism is evaluated by simulating multiplayer game scenarios and the results are compared with the hybrid IM mechanism as well as the well-established peer-to-peer NVE neighbor discovery mechanism VON.\",\n \"Title: An Efficient Sort-Based DDM Matching Algorithm for HLA Applications with a Large Spatial Environment\\nYear: 2007\\n\\nAbstract: Simulation is a low cost and safe alternative to solve complex problems in various areas. To promote reuse and interoperability of simulation applications and link geographically dispersed simulation components, distributed simulation was introduced. The High Level Architecture (HLA) is the IEEE standard for distributed simulation. To optimize communication efficiency between simulation components, HLA defines a Data Distribution Management (DDM) service group for filtering out unnecessary data exchange. It relies on the computation of overlap between update and subscription regions, which is called matching. In this paper, we propose an efficient sort-based DDM matching algorithm for HLA applications with a large spatial environment. A theoretical analysis of our algorithm concludes that it should have good storage and computational scalability. The experimental results have verified the theoretical conclusions by showing that our algorithm has much less storage requirement than the original sort-based matching algorithm and generally has the best computational performance when compared with region-based and the original sort-based matching algorithms.\",\n \"Title: Manufacturing sypply chain management: distributed supply chain simulation across enterprise boundaries\\nYear: 2000\\n\\nAbstract: The effective practice of supply chain management (SCM) is crucial to improve corporations' competitive advantage. Many corporations have built simulation models to facilitate the application of simulation in designing, evaluating, and optimizing their supply chain. Traditionally, a supply chain involves only a single enterprise with multiple facilities and distribution centers. Hence, sharing of detailed simulation models is not a problem in this scenario. But in recent years, the scope of SCM has evolved to cross the enterprise boundaries. Applying simulation in designing, evaluating, and optimizing the supply chain becomes more difficult since the participating corporations might not be willing to share their simulation models with partners. In this paper, distributed simulation techniques are presented as an enabling technology that allows corporations to construct a cross enterprise simulation while hiding model details within the enterprise. This can be realized by either building the simulation on top of the Runtime Infrastructure of the High Level Architecture or building the simulation on top of a customized distributed discrete event simulation protocol. These alternative approaches are compared in terms of their performance and interoperability. The comparison of the performance is done through a benchmarking test of a semiconductor supply chain model.\",\n \"Title: An auto-adaptive dead reckoning algorithm for distributed interactive simulation\\nYear: 1999\\n\\nAbstract: This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately handle the dynamic relationships between moving entities, a multi-level threshold scheme is proposed. The definition of threshold levels is based on the concepts of area of interest (AOI) and sensitive region (SR), and the levels of threshold are adaptively adjusted based on the relative distance between entities during the simulation. Various experiments were conducted. The results show that the proposed auto-adaptive dead reckoning algorithm can achieve considerable reduction in update packets without sacrificing accuracy in extrapolation\",\n \"Title: Grid-based partitioning for large-scale distributed agent-based crowd simulation\\nYear: 2012\\n\\nAbstract: Agent-based crowd simulation, which aims to simulate large crowds of autonomous agents with realistic behavior, is a challenging but important problem. One key issue is scalability. Parallelism and distribution is an obvious approach to achieve scalability for agent-based crowd simulation. Parallel and distributed agent-based crowd simulation, however, introduces its own challenges, in particular, effectively distributing workload amongst multiple nodes with minimal overhead. In order to ensure effective distribution with low overhead, a proper partitioning mechanism is required. Generally, human crowds consist of groups or exhibit particular patterns of flow, which are then reflected in simulations. Exploiting this grouping with an appropriate partitioning mechanism should enable efficient distribution of crowd simulation. In this paper we introduce a grid-based clustering algorithm which we compare to previous clustering approaches that used the K-means algorithm.\",\n \"Title: Evaluation of Java thread performance on two different multithreaded kernels\\nYear: 1999\\n\\nAbstract: Modern programming languages and operating systems encourage the use of threads to exploit concurrency and simplify program structure. An integral and important part of the Java language is its multithreading capability. Despite the portability of Java threads across almost all platforms, the performance of Java threads varies according to the multithreading support of the underlying operating system and the way Java Virtual Machine maps Java threads to the native system threads. In this paper, a well-known compute-intensive benchmark, the EP benchmark, was used to examine various performance issues involved in the execution of threads on two different multithreaded platforms: Windows NT and Solaris. Experiments were carried out to investigate thread creation and computation behavior under different system loads, and to explore execution features under certain extreme situations such as the concurrent execution of very large number of Java threads. Some of the experimental results obtained from threads were compared with a similar implementation using processes. These results show that the performance of Java threads differs depending on the various mechanisms used to map Java threads to native system threads, as well as on the scheduling policies for these native threads. Thus, this paper provides important insights into the behavior and performance of Java threads on these two platforms, and highlights the pitfalls that may be encountered when developing multithreaded Java programs.\",\n \"Title: An Information Service for Grid Virtual Organization: Architecture, Implementation and Evaluation\\nYear: 2005\\n\\nAbstract: Information Service is the heart of the entire Grid software infrastructure. It maintains various information in a Grid environment, and provides this information to users on request. We present an Information Service architecture for information capturing, aggregation, and provisioning in a Grid Virtual Organization (VO). This Information Service is a hierarchical structure which consists of VO layer, site layer and resource layer. The architecture defines downloadable and pluggable information sensors for portability and flexibility of information capturing. The meta-data mechanism is incorporated into our Information Service for information organization and management. Experiments were conducted to evaluate the performance of the Information Service, and the results show that the Information Service presents satisfactory scalability with number of users and number of information amount. Our Information Service has been implemented based on the Globus Toolkit as a Grid service compliant to the Open Grid Services Architecture (OGSA) specifications.\",\n \"Title: A peer-to-peer approach to task scheduling in computation grid\\nYear: 2005\\n\\nAbstract: Most of the existing solutions on task scheduling and resource management in grid computing are based on the traditional client/server\\n model, enforcing a homogenous policy on making decisions and limiting the system flexibility and scalability. In this paper,\\n we propose a peer-to-peer (P2P)-based decentralized approach, which off-loads the intermediate server by letting the peers\\n in the grid to make the scheduling decision among themselves using their own scheduling policies. A generic architecture for\\n metascheduler on peers, called PGS (P2P Grid Scheduler), and the task scheduling framework based on PGS have been developed. Both push and pull modes are used for distributing\\n the tasks to peers with the support of load balancing and fault tolerance. A prototype of the proposed architecture and mechanism\\n has been developed and simple performance tests have been conducted.\",\n \"Title: A Generic Symbiotic Simulation Framework\\nYear: 2006\\n\\nAbstract: A symbiotic or online simulation is defined as one that interacts with the physical system in a mutually beneficial way. The simulation is driven by real time data collected from a physical system under control and needs to meet the real-time requirements of the physical system. In turn, the results from the \\\"what-if\\\" experiments performed by the simulator can be used to control the dynamic behaviour of the physical system. Such a simulation tool is for real-time planning and is to foresee and advise on real time problems. It aims to improve performance, to adapt to sudden and unexpected events and to improve aspects of safety and security of the physical system.\",\n \"Title: Determining Optimal Update Period for Minimizing Inconsistency in Multi-server Distributed Virtual Environments\\nYear: 2011\\n\\nAbstract: The primary task of distributed virtual environments (DVEs) is to maintain a consistent view of the virtual world among all users. Multi-server architecture has been shown to have good scalability to support a large population of users in DVEs. However, some of the servers' resources like CPU, memory and network bandwidth can still get saturated as the scale of DVE increases. In this case, state updates cannot be disseminated timely and the consistency of the virtual world cannot be guaranteed. In this paper, we investigate how to efficiently use the limited resources for state update to minimize inconsistency in multi-server DVEs. Using time-space inconsistency metric, we firstly prove that periodic state update will result in minimal inconsistency for each replica. Then, in order to determine the optimal update periods for replicas to minimize the total time-space inconsistency of the DVE, we formulate the problem as a convex optimization problem with inequality constraints. Finally, an interior point method is adopted to solve the problem and the performance is evaluated using simulation results.\",\n \"Title: Compensatory dead-reckoning-based update scheduling for distributed virtual environments.\\nYear: 2013\\n\\nAbstract: In a distributed virtual environment (DVE), participants located in different places may observe inconsistent views of the simulated virtual world due to message delay and loss in the network. This paper investigates how to compensate for the impact of message delay and loss on consistency in the DVE. We focus on dead reckoning (DR)-based update mechanisms and measure inconsistency by the time-space inconsistency (TSI) metric. We theoretically analyze the TSI of an entity and derive the condition under which the impact of message delay and loss on consistency can be fully compensated for by reducing the DR threshold. Based on the analysis, a compensatory update scheduling algorithm is proposed. Experiments using real traces of a racing car game are conducted to evaluate the compensatory algorithm. The results confirm that if the condition derived in our theoretical analysis is fulfilled, the compensatory algorithm can decrease the TSI of a racing car to the level of the case without message delay and loss when there is sufficient network bandwidth available. Under severe bandwidth constraints, the compensatory algorithm still leads to comparable TSIs of the racing car among the participants regardless of their network conditions so as to enable fair competition.\",\n \"Title: Hierarchical interest management for distributed virtual environments.\\nYear: 2013\\n\\nAbstract: An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Distributed Virtual Environments (DVE). This paper proposes a new hierarchical IM mechanism for DVEs. The hierarchical mechanism divides the virtual world into multiple levels of cells and keeps the relationship between an entity and an Area-Of-Interest (AOI) at a particular cell level according to their relative position. As their relative position changes, the relationship level is updated accordingly. Compared with the traditional area-based and cell-based mechanisms, the proposed hierarchical mechanism significantly reduces the communication bandwidth consumption of IM and thus considerably improves the scalability of DVEs. In addition, the proposed mechanism also has much lower computation cost than the traditional mechanisms and very acceptable storage requirement for its data structures.\",\n \"Title: A replication structure for efficient and fault-tolerant parallel and distributed simulations\\nYear: 2010\\n\\nAbstract: Large scale parallel and distributed simulations (federations) are developed to study complex systems. Their executions are usually computationally intensive, involving a large number of simulation components (federates) which may be developed by different participants and executed at different locations. Hence, it is attractive to provide mechanisms which can accelerate the executions and tolerate the failures of federates. Previously, we have proposed a federate replication structure, which improves simulation performance by replicating federates with alternative synchronization approaches and automatically choosing the fastest replica to represent the federate in the federation execution. In this paper, we will extend the replication structure so that it keeps the advantages of performance enhancement in the presence of failures. Besides presenting the design and implementation details, we also report the experimental results to demonstrate that the extended replication structure can provide fault tolerance while maintaining performance advantages for simulation executions.\",\n \"Title: Interactivity-Constrained Server Provisioning in Large-Scale Distributed Virtual Environments\\nYear: 2012\\n\\nAbstract: Maintaining interactivity is one of the key challenges in distributed virtual environments (DVEs). In this paper, we consider a new problem, termed the interactivity-constrained server provisioning problem, whose goal is to minimize the number of distributed servers needed to achieve a prespecified level of interactivity. We identify and formulate two variants of this new problem and show that they are both NP-hard via reductions to the set covering problem. We then propose several computationally efficient approximation algorithms for solving the problem. The main algorithms exploit dependencies among distributed servers to make provisioning decisions. We conduct extensive experiments to evaluate the performance of the proposed algorithms. Specifically, we use both static Internet latency data available from prior measurements and topology generators, as well as the most recent, dynamic latency data collected via our own large-scale deployment of a DVE performance monitoring system over PlanetLab. The results show that the newly proposed algorithms that take into account interserver dependencies significantly outperform the well-established set covering algorithm for both problem variants.\",\n \"Title: Distributed Execution Of Workflow Using Parallel Partitioning\\nYear: 2009\\n\\nAbstract: Grid computing is a fundamental technology for large scale distributed resource sharing. Workflow management is becoming one of the most important Grid services. A lot of research work has been done on different issues involved in workflow management systems. The focus of this paper is on three areas: workflow partitioning, enactment and data movement. A new workflow management system called parallel and distributed workflow management system (PDWMS) is proposed. In this system the execution of workflow is done by a network of collaborative engines. To achieve this target, the original abstract workflow (input of the system) is partitioned into parallel parts, using a new proposed partitioning algorithm. PDWMS's data movement, which is categorized into local and global models, uses a peer-to-peer approach.\",\n \"Title: A virtualization-based approach for zone migration in distributed virtual environments\\nYear: 2011\\n\\nAbstract: This paper deals with the zone migration problem in large-scale distributed virtual environments (DVEs), e.g., massively multi-player online games, distributed military simulations, etc. To support real-time interactions among thousands of concurrent, geographically separated clients, a distributed server architecture is generally needed. In such architecture, the large virtual world can be partitioned into multiple smaller zones, enabling load distributions or zone-to-server mappings to improve interactivity. For example, a zone might be mapped (assigned) to a server location near most of its clients to reduce network latency. In this paper, we consider the problem of live zone migration over wide area networks (WANs) to support DVE zone re-mapping or load re-distribution in a geographically distributed server infrastructure. We propose a virtualization-based zone migration approach, and develop several migration algorithms to effectively migrate multiple DVE zones. We have implemented the proposed migration approach and algorithms in a tool for DVE performance enhancement and monitoring. Extensive experiments have also been conducted with an online multi-player game prototype constructed using the Torque 3D game engine. The results demonstrate the feasibility of our migration approach.\",\n \"Title: Consistency aware update schedule in multi-server Distributed Virtual Environments\\nYear: 2010\\n\\nAbstract: Multi-server architecture is very popular in Distributed Virtual Environments. Although multi-server architecture has good scalability, the load balance and consistency are still challenging issues. Because of server resource limitations (computation, communication etc), the consistency of the virtual world cannot be guaranteed sometimes. In this paper, we address this problem by developing scheduling polices and try to get better overall consistency with limited resources. We formulate the problem by using integer programming model and propose a centralized approximate algorithm. A distributed update strategy is also developed accordingly. Our algorithm is validated by theoretical analysis and wide range of experiments.\",\n \"Title: Performance prediction tools for parallel discrete-event simulation\\nYear: 1999\\n\\nAbstract: We have developed a set of performance prediction tools which help to estimate the achievable speedups from parallelizing a sequential simulation. The tools focus on two important factors in the actual speedup of a parallel simulation program: the simulation protocol used; and the inherent parallelism in the simulation model. The first two tools are a performance/parallelism analyzer for a conservative, asynchronous simulation protocol, and a similar analyzer for a conservative, synchronous (super-step) protocol. Each analyzer allows us to study how the speedup of a model changes with increasing number of processors, when a specific protocol is used. The third tool-a critical path analyzer-gives on ideal upper bound to the model's speedup. This paper gives an overview of the prediction tools, and reports the predictions from applying the tools to a discrete-event wafer fabrication simulation model. The predictions are close to speedups from actual parallel implementations. These tools help us to set realistic expectations of the speedup from a parallel simulation program, and to focus our work on issues which are more likely to yield performance improvement\",\n \"Title: A Decentralized Hierarchical Scheduler for a Grid-Based Clearinghouse\\nYear: 2003\\n\\nAbstract: Grid technologies enable large-scale resource sharing among enterprises and/or individuals. In such settings, control policies must be administered so that resource can be fairly shared among participating enterprises. A grid-based clearinghouse for managing shared resources is built with the aim of promoting technical and scientific cooperation within and between campuses. With that, we need a global mechanism for exchanging and integrating resource and hence, maximize computation throughput through the coordination of shared resources. The major process involved is the development of a job management strategy. In this paper, we will introduce the design and application of a decentralized hierarchical scheduler for job management in the clearinghouse.\",\n \"Title: Crowd modeling and simulation technologies\\nYear: 2010\\n\\nAbstract: As a collective and highly dynamic social group, the human crowd is a fascinating phenomenon that has been frequently studied by experts from various areas. Recently, computer-based modeling and simulation technologies have emerged to support investigation of the dynamics of crowds, such as a crowd's behaviors under normal and emergent situations. This article assesses the major existing technologies for crowd modeling and simulation. We first propose a two-dimensional categorization mechanism to classify existing work depending on the size of crowds and the time-scale of the crowd phenomena of interest. Four evaluation criteria have also been introduced to evaluate existing crowd simulation systems from the point of view of both a modeler and an end-user. We have discussed some influential existing work in crowd modeling and simulation regarding their major features, performance as well as the technologies used in this work. We have also discussed some open problems in the area. This article will provide the researchers with useful information and insights on the state of the art of the technologies in crowd modeling and simulation as well as future research directions.\",\n \"Title: Toward a Generic Framework for Modeling Human Behaviors in Crowd Simulation\\nYear: 2009\\n\\nAbstract: This paper presents our ongoing work on modeling agents with human-like decision making and behavior execution capabilities in crowd simulation. We aim to provide a generic framework that reflects the major cognitive and physical processes as observed from human behaviors in real-life situations. The design of the framework is based on some basic assumptions and related cognitive theories on human behaviors in various real-life situations. In this paper, the cognitive architecture of our framework is presented, which emphasizes the role of experiences in human's decision making. The paper also briefly describes the design of agent's decision making process and presents a case study to show some results in a crowd simulation scenario.\",\n \"Title: An integrated and adaptive decision-support framework for high-tech manufacturing and service networks\\nYear: 2005\\n\\nAbstract: This article describes the results of one of the ten pilot programmes under the Integrated Manufacturing and Service Systems (IMSS) initiative pursued by the Agency for Science, Technology and Research (A* STAR) in Singapore. The objective of this particular programme is to investigate how design, analysis, enhancement and implementation of critical business processes in a manufacturing and service network can be realised using one single simulation/application framework. The overall architecture of the framework outlines how commercial simulation packages and web-service based business process application components would have to be connected through a commercial application framework to achieve maximum leverage and re-usability of the applications involved. In the pilot phase of this programme, research issues were also addressed with regard to mechanisms for interoperation between commercial simulation packages, symbiotic interaction between simulation-based decision support components and physical systems, and simulation speed-up through multi-objective optimal computing budget allocation techniques on a grid infrastructure.\",\n \"Title: Causal Order Delivery in a Multicast Environment: An Improved Algorithm\\nYear: 2002\\n\\nAbstract: Causal order delivery of messages is required for many distributed applications. One of the problems with causal order delivery algorithms is the need to attach the dependency information with each message to ensure the causal ordering of delivery. This introduces a large amount of overhead and limits the scalability of the algorithm. To reduce the amount of dependency information, an algorithm was proposed by Prakash to attach only direct dependency information to the messages. The algorithm is optimal in a broadcast environment. However, in a multicast environment, it fails to eliminate indirect dependencies in some cases. In this paper, an improved causal order delivery algorithm that eliminates indirect dependencies in a broadcast as well as a multicast environment is proposed. The new algorithm is analyzed against Prakash's algorithm in terms of optimality on eliminating indirect dependencies. Simulation studies were also carried out to compare the performance of the two algorithms. The results show that the new algorithm incurs less communication overhead than Prakash's algorithm in all the cases.\",\n \"Title: Batch based cancellation: a rollback optimal cancellation scheme in time warp simulations\\nYear: 2004\\n\\nAbstract: An efficient cancellation scheme is essential to the performance of Time Warp simulations. The pitfalls of rollback echoes, chasing hazards and cascading rollbacks can be identified as being attributable to the inefficiency of the conventional per-event based cancellation scheme. Instead of capturing the happen-before relation between events, which is used by the range based cancellation scheme, the batch based cancellation scheme proposed in this paper utilizes a modified paradigm of vector time, namely, state vector, to capture the dependence of events. We prove that with conformance to specific rules regulating the advancement of LPs, the events to be cancelled by a straggler message can be determined using a range of the state vector. Thus, knowledge of the range enables any LP to recover from the receipt of a straggler message at the cost of at most one rollback (i.e., rollback optimal). The results of preliminary experiments conducted using a manufacturing model show that the proposed scheme is successful in reducing the number of anti-messages and increasing the ratio of the number of committed events to the number of processed events.\",\n \"Title: Agent-based human behavior modeling for crowd simulation\\nYear: 2008\\n\\nAbstract: Human crowd is a fascinating social phenomenon in nature. This paper presents our work on designing behavior model for virtual humans in a crowd simulation under normal-life and emergency situations. Our model adopts an agent-based approach and employs a layered framework to reflect the natural pattern of human-like decision making process, which generally involves a person's awareness of the situation and consequent changes on the internal attributes. The social group and crowd-related behaviors are modeled according to the findings and theories observed from social psychology (e.g., social attachment theory). By integrating our model into an agent execution process, each individual agent can response differently to the perceived environment and make realistic behavioral decisions based on various physiological, emotional, and social group attributes. To demonstrate the effectiveness of our model, a case study has been conducted, which shows that realistic human behaviors can be generated at both individual and group level. Copyright © 2008 John Wiley & Sons, Ltd.\",\n \"Title: A Hybrid Analysis of an Optimization Approach for Cluster Applications\\nYear: 2005\\n\\nAbstract: Cluster/distributed computing has become a popular, cost-effective alternative to high-performance parallel computers. Many parallel programming languages and related programming models have become widely accepted on clusters. However, the high communication overhead is a major shortcoming of running parallel applications on cluster/distributed computing environments. To reduce the communication overhead and thus the completion time of a parallel application, this paper introduces and evaluates an efficient Key Message (KM) approach to support parallel computing on cluster computing environments. In this paper, we briefly present the model and algorithm, and then analytical and simulation methods are adopted to evaluate the performance of the algorithm. It demonstrates that when network background load increases or the computation to communication ratio decreases, the analysis results show better improvement on communication of a parallel application over the system which does not use the KM approach.\",\n \"Title: Parallel Federates - An Architecture for Hybrid Distributed Simulation\\nYear: 2001\\n\\nAbstract: Abstract: In High Level Architecture (HLA) based distributed simulation, a federation is a set of federates, where each federate is normally executed sequentially. Our recent work on HLA-based distributed supply chain simulation shows that a federate with well above-par workload will become the performance bottleneck of the entire federation, since faster federates have to wait for the slower one to advance its simulation time. In this paper, we propose a parallel federate architecture which exploits the internal parallelism of a single federate. The parallel federate architecture is an integration of a parallel simulation protocol and HLA-based distributed simulation. A parallel federate can be executed on a SMP system to improve the performance of the entire federation. Our approach gains the advantages of both the interoperability, reusability and scalability of the HLA and faster execution of the parallel simulation protocol.\",\n \"Title: HumDPM: a decision process model for modeling human-like behaviors in time-critical and uncertain situations\\nYear: 2011\\n\\nAbstract: Generating human-like behaviors for virtual agents has become increasingly important in many applications, such as crowd simulation, virtual training, digital entertainment, and safety planning. One of challenging issues in behavior modeling is how virtual agents make decisions given some time-critical and uncertain situations. In this paper, we present HumDPM, a decision process model for virtual agents, which incorporates two important factors of human decision making in time-critical situations: experience and emotion. In HumDPM, rather than relying on deliberate rational analysis, an agent makes its decisions by matching past experience cases to the current situation. We propose the detailed representation of experience case and investigate the mechanisms of situation assessment, experience matching and experience execution. To incorporate emotion into HumDPM, we introduce an emotion appraisal process in situation assessment for emotion elicitation. In HumDPM, the decision making process of an agent may be affected by its emotional states when: 1) deciding whether it is necessary to do a re-match of experience cases; 2) determining the situational context; and 3) selecting experience cases. We illustrate the effectiveness of HumDPM in crowd simulation. A case study of two typical crowd scenarios is conducted, which shows how a varied crowd composition leads to different individual behaviors, due to the retrieval of different experiences and the variation of agents' emotional states.\",\n \"Title: Employing economics to achieve fairness in usage policing of cooperatively shared computing resources\\nYear: 2005\\n\\nAbstract: A cooperative virtual organization (VO) is formed when distinct organizations pool their computing and data resources together. In a typical VO, there is no central authority that governs the amount of resources that each organization should contribute to the community. To prevent free-riding on shared resources, we introduce policies to curb excessive usage in an equitable manner. While centralized schemes are simple, they are generally inefficient due to the presence of irregular workload traffic. This paper theoretically demonstrates how under specific conditions, an economy-based framework can be designed to achieve fairness. From our formalization, we conceptually show that agent homogeneity and load-based pricing schemes on shared resources can help achieve this requirement.\",\n \"Title: Cluster based partitioning for agent-based crowd simulations\\nYear: 2009\\n\\nAbstract: Simulating crowds is a challenging but important problem. There are various methodologies in the literature ranging from macroscopic numerical flow simulations to detailed, microscopic agent simulations. One key issue for all crowd simulations is scalability. Some methods address this issue through abstraction, describing global properties of homogeneous crowds. However, ideally a modeler should be able to simulate large heterogeneous crowds at fine levels of detail. We are attempting to achieve scalability through the application of distributed simulation techniques to agent-based crowd simulation. Distributed simulation, however, introduces its own challenges, in particular how to efficiently partition the load between a number of machines. In this paper we introduce a method of partitioning agents onto machines using an adapted k-means clustering algorithm. We present, validate and use an analysis tool to compare the proposed clustered partitioning approach with a series of existing methods.\",\n \"Title: Toward an Evolutionary Computing Modeling Language\\nYear: 2011\\n\\nAbstract: The importance of domain knowledge in the design of effective evolutionary algorithms (EAs) is widely acknowledged in the meta-heuristics community. In the last few decades, a plethora of EAs has been manually designed by domain experts for solving domain-specific problems. Specialization has been achieved mainly by embedding available domain knowledge into the algorithms. Although programming libraries have been made available to construct EAs, a unifying framework for designing specialized EAs across different problem domains and branches of evolutionary computing does not exist yet. In this paper, we address this issue by introducing an evolutionary computing modeling language (ECML) which is based on the unified modeling language (UML). ECML incorporates basic UML elements and introduces new extensions that are specially needed for the evolutionary computation domain. Subsequently, the concept of meta evolutionary algorithms (MEAs) is introduced as a family of EAs that is capable of interpreting ECML. MEAs are solvers that are not restricted to a particular problem domain or branch of evolutionary computing through the use of ECML. By separating problem-specific domain knowledge from the EA implementation, we show that a unified framework for evolutionary computation can be attained. We demonstrate our approach by applying it to a number of examples.\",\n \"Title: A scalable architecture for supporting interactive games on the internet\\nYear: 2002\\n\\nAbstract: This paper presents a scalable architecture for supporting large-scale interactive Internet games. In order to support a large number of participants and to divide the workload, the virtual world is divided into partitions. Each partition is then assigned to a server. A client (i.e., a player or a participant) will join a server according to the position of the avatar it controls. Compared to a centralized architecture, this distributed client-server architecture is more scalable. In addition, compared to a fully distributed, peer-to-peer architecture, it also provides a means for detecting cheating in distributed games. Since interactions and accounting information must be forwarded directly to one of the servers for qualification and verification, cheating amongst distributed players of the game will be minimized. To support secured communication for interactions and accounting information as well as to speedup periodic update messages (e.g., position updates), a hybrid communication scheme using both TCP and IP multicast is used between clients and the associated server. The communication among servers is enabled by the Run-Time Infrastructure (RTI) services. The High Level Architecture (HLA) Data Distribution Management (DDM) is employed to limit the amount of communication between the servers. In addition, the Ownership Management (OM) is also employed to implement the need for transferring the avatars between servers. In this paper, the design detail of the architecture will be presented. An experimental interactive Internet game realized using the architecture will be also described in the paper.\",\n \"Title: Grid Services and Service Discovery for HLA-Based Distributed Simulation\\nYear: 2004\\n\\nAbstract: Modelling and simulation permeate all areas of business, science and engineering and increasingly complex simulation systems often require huge computing resources and data sets that are geographically distributed. The widely adopted platform for building distributed simulations is the High Level Architecture (HLA). Deficiencies associated with HLA have been well discussed in the literature. The advent of Grid technology enables the use of distributed computing resources and facilitates the access of geographically distributed data. In this paper, we propose a framework for executing large-scale distributed simulations using Grid services. The framework addresses some of the deficiencies of HLA, including dynamic discovery and resource utilization. End-users can construct large-scale distributed simulations using this framework with ease.\",\n \"Title: Dynamic specialization for symbiotic simulation-based operational decision support using the evolutionary computing modelling language (ECML).\\nYear: 2014\\n\\nAbstract: Simulation-based what-if analysis is an important tool that can be used to support operational decision making. Solutions to operational decision problems have to be found in a limited period of time. As a result of these time constraints, not all candidate solutions can be evaluated by means of simulation. Essentially, this problem solving process is an optimization process. Specialization of the optimization method can help to reduce the computing budget needed to find an appropriate solution. However, since operational conditions are constantly changing, the exact problem is not known at design time. Therefore, the optimization method has to be specialized during runtime. This can be done by dynamically incorporating situation-dependent problem-specific knowledge into the optimization process. We introduce a method based on an evolutionary algorithm, which supports dynamic specialization. Furthermore, we demonstrate the effectiveness of this method in the context of a semiconductor manufacturing application.\",\n \"Title: Enhancement of Collaborative Interest Management Mechanism for P2P Networked Virtual Environment\\nYear: 2012\\n\\nAbstract: Interest Management (IM) aims at eliminating irrelevant state updates transmitted in Networked Virtual Environment (NVE), such as online games. The existing IM mechanisms include area-based, cell-based mechanisms and hybrid IM mechanism which reduces the communication overhead by utilizing the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism. Comparing to the existing IM mechanisms, the recently proposed collaborative IM mechanism (CIM) successfully reduces the communication cost further. However, two problems exist in the current CIM mechanism: i) the protocol may fail under certain circumstances, and ii) the protocol requires dividing the virtual environment into fixed grids. In this paper, we focus on the approaches that could enhance the current CIM mechanism and we will evaluate the performance using simulation of multiplayer game scenarios.\",\n \"Title: Adaptive Policing for Token-Exchange Based Management of Shared Computing Resources\\nYear: 2006\\n\\nAbstract: Resource contention on shared resources occurs when workload demands exceed the aggregate capacity of shared resources in the community. The token-exchange incentive scheme is traditionally employed to motivate organizations to contribute sufficiently to the community, as a means to minimize free riding. The same incentive scheme can concurrently be used to serve as a mechanism for performing admission control on jobs submitted by users. However, due to the likelihood of fluctuations in demand for computing resources, the initial assignment of tokens on the basis of each organization's resource contribution, may have a significant impact on the performance trade-off between fairness and the system admission ratio. To address this problem, we extend the token-exchange scheme by designing trading policies that are responsive to the instantaneous degree of contention, so that, the trade-off between fairness and the admission ratio is less sensitive to the actual quantity of tokens assigned to each organization.\",\n \"Title: Hierarchical federations: an architecture for information hiding\\nYear: 2001\\n\\nAbstract: In a distributed simulation, simulation components of various types are executed at geographically different locations, forming a simulation federation to create a common virtual environment. Under the High Level Architecture (HLA), information that will be produced and consumed by a simulation component is defined in its object model, and how that information is produced and consumed is well encapsulated inside the simulation component's implementation. However in the current implementation of the HLA's Runtime Infrastructure (RTI), information hiding between groups of simulation components in a simulation federation is not addressed. The authors discuss how hierarchical federation architectures can be used to tackle this problem. The hierarchical federation architecture adopted in the paper differs from the existing architectures in that it is based on a hybrid approach for interoperability between simulation federations. To demonstrate information hiding using the architecture, a distributed semiconductor supply-chain simulation is also described\",\n \"Title: JBSP: a BSP programming library in Java\\nYear: 2001\\n\\nAbstract: In this paper, we introduce a Java implementation of the Bulk Synchronous Parallel(BSP) model. JBSP (a Java-based BSP system) uses a two-daemon architecturewhich makes a clear separation of the computation and communication involvedin parallel programs. Java threads are used in the implementation of the JBSPsystem to realize user dened JBSP tasks as well as to carry out system activities.\",\n \"Title: Implementation Lessons of Performance Prediction Tool for Parallel Conservative Simulation (Research Note)\\nYear: 2000\\n\\nAbstract: Performance prediction is useful in helping parallel programmers answer questions such as speedup scalability. Performance prediction for parallel simulation requires first working out the performance analyzer algorithms for specific simulation protocols. In order for the prediction results to be close to the results from actual parallel executions, there are further considerations when implementing the analyzer. These include (a) equivalence of code between the sequential program and parallel program, and (b) system effects (e.g. cache miss rates and synchronization overheads in an actual parallel execution). This paper describes our investigations into these issues on a performance analyzer for a conservative, \\\"super-step\\\" (synchronous) simulation protocol.\",\n \"Title: Workload management of cooperatively federated computing clusters\\nYear: 2006\\n\\nAbstract: Cooperative resource sharing enables distinct organizations to form a federation of computing resources. The motivation behind cooperation is that organizations are likely to serve each other by trading unused CPU cycles given the existence of irregular usage patterns of their local resources. In this way, resource sharing would enable organizations to purchase resources at a feasible level while meeting peak computational throughput requirements. This federation results in community grid that must be managed. A functional broker is deployed to facilitate remote resource access within the community grid. A major issue is the problem of correlations in job arrivals caused by seasonal usage and/or coincident resource usage demand patterns. These correlations incur high levels of burstiness in job arrivals causing the job queue of the broker to grow to an extent such that its performance becomes severely impaired. Since job arrivals cannot be controlled, management strategies must be employed to admit jobs in a manner that can sustain a fair level of resource allocation performance at all participating organizations in the community. In this paper, we present a theoretical analysis of the problem of job traffic burstiness on resource allocation performance in order to elicit the general job management strategies to be employed. Based on the analysis, we define and justify a job management strategies for the resource broker to cope with overload conditions caused by job arrival correlations.\",\n \"Title: A Framework for Robust HLA-based Distributed Simulations\\nYear: 2006\\n\\nAbstract: The High Level Architecture (HLA) is a standard for the interoperability and reuse of simulation components, referred to as federates. Large scale HLA-compliant simulations are built to study complex problems, and they often involve a large number of federates and vast computing resources. Simulation federates running at different locations are liable to failure. The failure of one federate can lead to the crash of the overall simulation execution. Such risk increases with the scale of a distributed simulation. Hence, fault-tolerance is required to support runtime robustness. This paper introduces a framework for robust HLAbased distributed simulations using a \\\"Decoupled Federate Architecture. Our framework exploits the architecture to provide a generic fault-tolerant model, that exploits a \\\"dynamic substitution approach to deal with failure. A sender-based method is designed to ensure reliable in-transit message delivery, which is coupled with a novel algorithm to perform effective fossil collection. The fault-tolerant model also avoids any unnecessary repeated computation when handling failure. The framework supports reusability of legacy federate code, and it is platform-neutral and independent of federate modeling approaches. Experiments have been carried out to validate and benchmark the fault-tolerant federates using an example of a simple supply-chain simulation. The experimental results show that the framework provides correct failure recovery and indicate that the overhead for facilitating fault-tolerance is minimal.\",\n \"Title: Large Scale Distributed Simulation on the Grid\\nYear: 2006\\n\\nAbstract: The developmentof many complex siumulation applications requires collaborrrtive effortfrom reseachers with different domain knowledge and expertise,possibly at different locations. These simulations systems often require huge computing resources and data set, which may be geo- graphically distribyted,In ordr to support collaborative model development and to cater for the increasing comoplex- ity of such systems, it is necessary to harness distributed resources over the Internet.the emergence of Grid tech nologies provide exciting new opportunities for large scale distributed simulation, enabling collaboration and the use of distributed computing resources, while also facilitating access to geographically distributed data sets. This paperdiscusses the research challenges that must be addressesbefore these opportunities can be exploited and presents HLA-GRID_REPast, a system for executing large scale distributed simulations of agent based systems over the Grid.\",\n \"Title: A Framework for Performance Evaluation of Large-scale Interactive Distributed Virtual Environments\\nYear: 2010\\n\\nAbstract: Interactivity is a key consideration in large-scale distributed virtual environments (DVEs), such as massively multi-player online games. Due to the Internet dynamics as well as the large-scale and distributed nature of many DVEs, it is difficult to quantify the possible improvements claimed by various DVE interactivity enhancement approaches. In this paper, we propose a scalable framework that supports evaluation of interactivity indicators, under dynamic Internet conditions. We have developed and used this framework to conduct extensive experiments on PlanetLab with many distributed client and server locations. We have collected the latency experienced by over 700 client locations distributed around the globe over a few days; and used it for evaluating performance of some recently proposed zone mapping algorithms.\",\n \"Title: A framework of evaluating partitioning mechanisms for agent-based simulation systems\\nYear: 2009\\n\\nAbstract: For an agent-based system that aims to simulate a large number of agents under different scenarios, a proper partitioning mechanism is an essential factor to the performance of the system. However, there is still an issue on selecting/developing an appropriate partitioning mechanism for a specific agent-based simulation system. One way is to implement distributed agent-based systems using multiple partitioning mechanisms and to compare their performance. However this is in general not feasible. In this paper, we propose a generic framework and a simple evaluation process to address the issue of selecting an appreciate partitioning mechanism by simulating the effect of the partitioning mechanism to predict its performance for an agent-based simulation system.\",\n \"Title: Critical causal order of events in distributed virtual environments\\nYear: 2007\\n\\nAbstract: We investigate the causal order of events in distributed virtual environments (DVEs). We first define the critical causal order relation among the events. Then, we propose some mechanisms to enhance the prevalent RO (receive order delivery) mechanism in DVEs so that the real-time property of DVEs is preserved while the critical causal order violations are reduced. These mechanisms are implemented as a middleware. Experimental results show that the middleware performs well in reducing the critical causality violations in simulation and incurs little processing overhead.\",\n \"Title: Multi-user Gaming on the Grid Using a Service Oriented HLA RTI\\nYear: 2009\\n\\nAbstract: Interactive multi-user Internet games require frequent state updates between players to accommodate the great demand for reality and interactivity. The large latency and limited bandwidth on the Internet greatly affects the game’s scalability. The High Level Architecture (HLA) is the IEEE standard for distributed simulation with its Data Distribution Management (DDM) service group assuming the functionalities of interest management. With its support for reuse and interoperability and its DDM support for communication optimization, the HLA is promising at supporting multi-user gaming on the Internet. However, this usually requires particular prior security setup across administrative domains according to the specific Run Time Infrastructure (RTI) used. We have previously developed a Service Oriented HLA RTI (SOHR) which enables distributed simulations to be conducted across administrated domains on the Grid. This paper discusses multi-user gaming on the Grid using SOHR. Specifically, a maze game is used to illustrate how SOHR enables users to join a game conveniently. Experiments have been carried out to show how DDM can improve the communication efficiency.\",\n \"Title: Time management in a service-oriented architecture for distributed simulation on the grid\\nYear: 2007\\n\\nAbstract: A Service-Oriented Architecture is essentially a collection of independent services with well-defined interfaces that can be accessed without knowledge of their implementation. The architecture is widely used in Grid computing to achieve resource virtualization, on-demand provisioning, and service (resource) sharing. As the Grid has shown its potential as a suitable environment for simulation and modeling, a Service-Oriented Architecture for Distributed Simulation on the Grid (SOAr-DSGrid) was proposed. Like other simulation systems, time management is a crucial part of the whole system. It manages the logical time and guarantees that the whole simulation system is causally correct. This paper describes the implementation of distributed time management in SOAr-DSGrid. The time management makes use of the simulation topology information to reduce constraints on time advancement between simulation components. Various experiments conducted on a cluster demonstrate that a fully distributed time management system has better scalability and efficiency than the centralized version.\",\n \"Title: Parallel discrete event simulation of manufacturing systems using parsec\\nYear: 2000\\n\\nAbstract: Most existing Parallel Discrete Event Simulation (PDES) languages are general-purpose simulation languages, which are useful for constructing general simulation applications. However, they lack features to support special models, such as those in manufacturing simulation. In a study of a wafer fabrication simulation, one feature that complicates the implementation using a general-purpose PDES language is the specification of dispatching and setup rules. This paper studies the performance of different implementation alternatives of a wafer fabrication simulation using an existing general-purpose PDES language. In our study, the wafer fabrication simulation model is based on the Sematech Data Modeling Standard, and PARSEC is selected as the general-purpose PDES language.\",\n \"Title: Modeling Human-Like Decision Making for Virtual Agents in Time-Critical Situations\\nYear: 2010\\n\\nAbstract: Generating human-like behaviors for virtual agents has become increasingly important in many applications, such as crowd simulation, virtual training, digital entertainment, and safety planning. One of challenging issues in behavior modeling is how virtual agents make decisions given some time-critical and uncertain situations. In this paper, we present HumDPM, a decision process model for virtual agents, which incorporates two important factors of human decision making in time-critical situations: experience and emotion. In HumDPM, rather than relying on deliberate rational analysis, an agent makes its decisions by matching past experience cases to the current situation. We propose the detailed representation of experience case and investigate the mechanisms of situation assessment, experience matching and experience execution. To incorporate emotion into HumDPM, we introduce an emotion appraisal process in situation assessment for emotion elicitation. In HumDPM, the decision making process of an agent may be affected by its emotional states when: 1) deciding whether it is necessary to do a re-match of experience cases, 2) determining the situational context, and 3) selecting experience cases. We illustrate the effectiveness of HumDPM in crowd simulation. A case study for emergency evacuation in a subway station scenario is conducted, which shows how a varied crowd composition leads to different evacuation behaviors, due to the retrieval of different experiences and the variation of agents' emotional states.\",\n \"Title: A Data-Driven Crowd Simulation Model Based on Clustering and Classification\\nYear: 2013\\n\\nAbstract: In this paper, we propose a data-driven crowd behavior model that is constructed by extracting examples from human motion data describing how humans make decisions. We cluster the examples before the simulation to find similar patterns of behavior. During the simulation, at each simulation time step, we first classify the input state perceived by an agent in the simulation into one example cluster using an artificial neural network classifier. We then combine similar examples of that cluster to produce an output, a velocity vector indicating the position of the agent in the next time step. Such a two step matching process enables the selection of the most similar example accurately and efficiently. To verify our approach, we have developed an initial prototype in which we build our model using motion data generated by a RVO2 simulator, attempting to reproduce the behavior of the RVO2 model. By comparing the position of the same agent simulated by the RVO2 mode land our model respectively at the same time steps, we show that our model has the ability to reproduce the behavior of the RVO2 model accurately. As future work, we will use real human motion data as model input, so that our model may perform human-like motion behavior.\",\n \"Title: Execution coordination in mobile agent-based distributed job workflow execution\\nYear: 2008\\n\\nAbstract: Mobile agent-based distributed job workflow execution requires the use of execution coordination techniques to ensure that an agent executing a subjob can locate its predecessors' execution results. This paper describes the classification, implementation, and evaluation of execution coordination techniques in the mobile agent-based distributed job workflow execution system. First, a classification of the existing execution coordination techniques is developed for mobile agent systems. Second, to put the discussion into perspective, our framework for mobile agent-based distributed job workflow execution over the Grid (that is, MCCF: Mobile Code Collaboration Framework) is described. How the existing coordination techniques can be applied in the MCCF is also discussed. Finally, a performance study has been conducted to evaluate three coordination techniques using real and simulated job workflows. The results are presented and discussed in the paper.\",\n \"Title: Synchronization in federation community networks\\nYear: 2010\\n\\nAbstract: A large scale High Level Architecture (HLA)-based simulation can be constructed using a network of simulation federations to form a ''federation community''. This effort is often for the sake of enhancing scalability, interoperability, composability and enabling information security. Synchronization mechanisms are essential to coordinate the execution of federates and event transmissions across the boundaries of interlinked federations. We have developed a generic synchronization mechanism for federation community networks with its correctness mathematically proved. The synchronization mechanism suits various types of federation community network and supports the reusability of legacy federates. It is platform-neutral and independent of federate modeling approaches. The synchronization mechanism has been evaluated in the context of the Grid-enabled federation community approach, which allows simulation users to benefit from both Grid computing technologies and the federation community approach. A series of experiments has been carried out to validate and benchmark the synchronization mechanism. The experimental results indicate that the proposed mechanism provides correct time management services to federation communities. The results also show that the mechanism exhibits encouraging performance in terms of synchronization efficiency and scalability.\",\n \"Title: Dynamic load-balancing in a data parallel object-oriented system\\nYear: 2001\\n\\nAbstract: In this paper, a parallel object collection (POC) model is introduced to support data parallelism in a parallel object-oriented system. This model is based on the idea of data partitioning and method replication. To achieve load-balancing, partition objects are dynamically migrated at runtime according to the system load situation. A threshold-based strategy is used in the dynamic load-balancing. To avoid over-convergence of load during partition object migration, a new destination node selection algorithm is proposed. The threshold values used in the algorithm are also adaptively adjusted to better reflect the fluctuation of the load during execution. To evaluate the performance of the dynamic load balancing algorithm, simulation experiments are conducted. The simulation results are reported and discussed in the paper.\",\n \"Title: Preventive what-if analysis in symbiotic simulation\\nYear: 2008\\n\\nAbstract: The what-if analysis process is essential in symbiotic simulation systems. It is responsible for creating a number of alternative what-if scenarios and evaluating their performance by means of simulation. Most applications use a reactive approach for triggering the what-if analysis process. In this paper we describe a preventive triggering approach which is based on the detection of a future critical condition in the forecast of a physical system. With decreasing probability of a critical condition, using preventive what-if analysis becomes undesirable. We introduce the notion of a G-value and explain how this metric can be used to decide whether or not to use preventive what-if analysis. In addition, we give an example for a possible application in semiconductor manufacturing.\",\n \"Title: Flexible State Update Mechanism for Large-Scale Distributed Wargame Simulations\\nYear: 2007\\n\\nAbstract: Large-scale wargame simulations may involve tens of thousands of entities and generally run on distributed simulation nodes. An important issue in constructing these applications is to reduce the amount of data transmitted among the distributed simulation nodes so that the network and the simulation nodes will not be flooded by the state update messages. To this end, we first propose a timeliness condition on how frequently the state updates of a local simulation entity need to be sent to other remote simulation nodes. A fleXible state update mechanism is then proposed to ensure the update intervals of the entities meet the required timeliness update condition and, in the meantime, balance the number of entities that need to be updated in each simulation time step (referred to here as the frame). EXperiments with a distributed wargame simulation indicate that the proposed mechanism can significantly reduce the number of messages sent over the network while still maintaining the simulation fidelity.\",\n \"Title: Provenance Provisioning in Mobile Agent-Based Distributed Job Workflow Execution\\nYear: 2007\\n\\nAbstract: Job workflow systems automate the execution of scientific applications, however they may hide how the results are achieved (i.e., the provenance information of the job workflow execution). This paper describes the development and evaluation of a decentralized recording and collection scheme for job workflow provenance in mobile agent-based distributed job workflow execution. A performance study was conducted to evaluate our approach against the one using a centralized provenance server. The results are discussed in the paper.\",\n \"Title: A Computational Model of Emotions for Agent-Based Crowds in Serious Games\\nYear: 2011\\n\\nAbstract: Crowd behaviour is an interesting social phenomenon that emerges from complex interactions of individuals. An important aspect of individual behaviour is emotion which plays a significant role in all aspects of human decision making. For example, heightened emotional states can lead people to take highly unexpected or irrational actions. One popular motivation for simulation of virtual crowds is to generate believable characters in movies and computer games. Recently the concept of serious games has been introduced in both academic and industrial circles. In this paper, we propose an emotion engine, based on modern appraisal theory, that is able to model various emotional crowd characteristics. This appraisal engine is capable of capturing the dynamics of emotional contagion and we show how different crowd composition can lead to different patterns of emotional contagion. In addition, we describe a serious game designed for training military personnel in peaceful crowd control. We evaluate this engine in the context of a property protection protest scenario where the players or soldiers are tasked to maintain a peaceful protest without violence. A systematic evaluation is presented which supports the facial validity of the emotion engine and our model of emotional contagion.\",\n \"Title: A decoupled federate architecture for high level architecture-based distributed simulation\\nYear: 2008\\n\\nAbstract: A number of research issues arise in executing large scale High Level Architecture (HLA) based distributed simulations. Among these issues distributed simulation cloning, fault tolerance and Grid enabled architecture are particularly important and challenging. This paper presents a Decoupled Federate Architecture as the underlying infrastructure to facilitate a solution to each of the above issues. Distributed simulation cloning has been designed to improve the performance of ''what-if'' analysis, by enabling the examination of alternative scenarios concurrently within the same execution session. Furthermore, simulation federates running at different locations are liable to failure. Such risk increases with the scale of a distributed simulation. The architecture has also been exploited to form the basis of a generic framework to support runtime robustness. The development of complex simulation applications often requires geographically distributed huge computing resources and data sets. Using the architecture, Web and Grid technologies have been successfully combined with existing simulation technologies thus to enhance interoperability and execution flexibility for such simulations. Benchmark experiments have been performed to study the extra overhead incurred by the Decoupled Federate Architecture against a normal federate. Encouraging experimental results indicate that a well designed architecture can achieve performance close to the normal one in terms of latency and time synchronization. Additional experiments have been presented for evaluating the three solutions supported by the architecture.\",\n \"Title: Graphical views of the behavior of parallel programs\\nYear: 1993\\n\\nAbstract: There is often an increasing gap between a programmer′s mental conception of a problem and the realization of a parallel program which solves that problem. To bridge this gap, information about program execution must be displayed. Since a parallel program may be executed on several processors simultaneously, activities may be distributed across both space and time, and therefore simple sequential displays of a program′s execution are inadequate. Intuitively, pictures are much more meaningful than text, particularly with parallel programs where large quantities of information may be generated. In this paper, we describe how the behavior of parallel programs may be graphically interpreted, and discuss current approaches and difficulties in parallel program visualization. A graphical interface designed for languages based on message-passing is also presented.\",\n \"Title: A Simulation Study of Dynamic Load Balancing for Network-based Parallel Processing\\nYear: 1997\\n\\nAbstract: A simulation study of dynamic load balancing for parallel processing on Network Of Workstations (NOW) is presented in this paper. A simulation model is constructed. It includes a representative CPU scheduling policy, and also considers the message exchange, task transfer and migration costs explicitly. A global dynamic load balancing algorithm is simulated. Both task transfer and task migration are considered. The performance of the algorithm under both homogeneous and heterogeneous environments is analyzed. In addition, the interaction of parallel and sequential workloads on an NOW is also examined. Our results show that dynamic load balancing can achieve better performance improvement for heterogeneous systems than for homogeneous systems; it is especially effective in a system where both parallel and sequential tasks concurrently exist; and the use of task migration generally does not further improve performance.\",\n \"Title: Application Layer Multicast in P2P Distributed Interactive Applications\\nYear: 2013\\n\\nAbstract: By sharing resources among peers in peer-to-peer network, application layer multicast (ALM) has been shown an efficient way to improve the scalability and reduce the latency of communication. To deploy ALM in peer-to-peer distributed interactive applications (DIAs), the property of many-to-many communication of DIA demands multiple multicast trees to be constructed in the overlay. Therefore, how to efficiently allocate resources among multiple trees to maximize the benefit is an important and challenging issue. In this paper, we study the problem of building ALM trees with minimum total end-to-end delay to receivers in peer-to-peer DIAs with resource constraints on network bandwidth. The end-to-end delay from a sender to receivers in a multicast tree consists of the link delay as well as the packet queuing delay at intermediate peers, while the latter is often ignored or not well studied in the previous work. In this paper, we explicitly establish the relationship between the queuing delay at peers and the topology of multicast trees in peer-to-peer DIAs. Based on the relationship, the above mentioned problem is defined and we prove that it is NP-complete. We present a centralized heuristic algorithm to obtain an approximate solution. Moreover, distributed algorithms are also investigated to refine the topology in practical systems with dynamic changes. Extensive experiments were conducted by simulations to evaluate the proposed algorithms and results are reported in the paper.\",\n \"Title: Towards Fault-tolerant HLA-based Distributed Simulations\\nYear: 2008\\n\\nAbstract: Large scale High Level Architecture (HLA)-based simulations are built to study complex problems, and they often involve a large number of federates and vast computing resources. Simulation federates running at different locations are subject to failure. The failure of one federate can lead to the crash of the overall simulation execution. Such risk increases with the scale of a distributed simulation. Hence, fault tolerance is required to support runtime robustness. This paper introduces a framework for robust HLA-based distributed simulations using a 'Decoupled Federate Architecture'. The framework provides a generic fault-tolerant model, which deals with failure with a dynamic substitution approach. A sender-based method is designed to ensure reliable in-transit message delivery, which is coupled with a novel algorithm to perform effective fossil collection. The fault-tolerant model also avoids any unnecessary repeated computation when handling failure. Using a middleware approach, the framework supports reusability of legacy federate code and it is platform-neutral and independent of federate modeling approaches. Experiments have been carried out to validate and benchmark the fault-tolerant federates using an example of a supply-chain simulation. The experimental results show that the framework provides correct failure recovery. The results also indicate that the framework only incurs minimal overhead for facilitating fault tolerance and has a promising scalability.\",\n \"Title: DPBP: a sort-first parallel rendering algorithm for distributed rendering environments\\nYear: 2003\\n\\nAbstract: In some visualization systems, the data and computational resources are distributed globally and users need to interact with these resources easily and efficiently. Real-time rendering for massive datasets is a computation intensive task. one solution is to distributes the rendering tasks over a set of computation units to achieve high rendering performance. This paper presents a recursive sort-first partitioning algorithm named Dynamic Pixel Bucket Partition (DPBP) for parallel rendering alone with their implementation and performance in a distributed rendering environment. This algorithm distributes rendering work loads evenly to individual rendering units to achieve fast, high quality rendering of massive data. Test results in a multi-cluster environment demonstrate the practicality of this rendering algorithm.\",\n \"Title: Managing event traces for a web front-end to a parallel simulation\\nYear: 2001\\n\\nAbstract: To enhance the widespread use of a parallel supply chain simulator, a web front-end that enables access at any time and from any location has been developed. The front-end provides the capability of model uploading, simulation runs initiation, simulation activities visualization, and simulation statistics collection. Visualizing the simulation activities requires the parallel simulator to record event traces to the file system for displaying purposes. To minimize the negative impact of the recording on the performance of parallel simulation, an event trace management algorithm, coupled with a buffering mechanism, is proposed. The approach was evaluated using six sample supply chain models. The results show that the proposed algorithm is capable of maintaining the same level of speedup when recording is performed (in the range of 2.5 to 3.0 on a 4-CPU shared memory system), as compared to runs without recording of event traces\",\n \"Title: Network-Aware Server Placement for Highly Interactive Distributed Virtual Environments\\nYear: 2008\\n\\nAbstract: In distributed virtual environments, e.g., online gaming, collaborative designs and distributed military simulations, interactivity is one of the most important requirements. The users may notice serious degradations in quality of service when interacting in the virtual world if the response from the system is much slower than what they have experienced in real life. In this paper, we consider the problem of placing distributed servers in the network to reduce client-server communication latencies, which is termed the server placement problem. We proposed two new network-aware placement algorithms which take into account users' locations in the network and connectivity at the Autonomous System level to determine good sites for servers. Extensive experiments with realistic network models showed that these new algorithms significantly outperform existing approaches that require full knowledge of network connectivity at the router-level topologies.\",\n \"Title: A Distributed Rendering Environment for Massive Data on Computational Grids\\nYear: 2003\\n\\nAbstract: Scientific visualization, especially for massive data sets, has emerged in different disciplines recently. Generally, distributed scientific visualization applications require multiple resources, e.g., high-end computing resources to process data, high speed network for data transfer and large size database for data storage. Furthermore, these applications will meet research challenges, e.g., heterogeneous resources, geographically distributed environment and considerable communication delay. This paper studies an application of distributed massive data rendering. We present infrastructure of the distributed rendering environment and explain how Grid technologies are used in this application. Dynamic Pixel Bucket Partition (DPBP) algorithm is a new algorithm proposed for task allocation of distributed rendering application in computational Grids. Experiments in real test ted shows the performance of DPBP algorithm and the framework.\",\n \"Title: Autonomous Bee Colony Optimization for multi-objective function\\nYear: 2010\\n\\nAbstract: An Autonomous Bee Colony Optimization (A-BCO) algorithm for solving multi-objective numerical problems is proposed. In contrast with previous Bee Colony algorithms, A-BCO utilizes a diversity-based performance metric to dynamically assess the archive set. This assessment is employed to adapt the bee colony structures and flying patterns. This self-adaptation feature is introduced to optimize the balance between exploration and exploitation during the search process. Moreover, the total number of search iterations is also determined/optimized by A-BCO, according to user pre-specified conditions, during the search process. We evaluate A-BCO upon numerical benchmark problems and the experimental results demonstrate the effectiveness and robustness of the proposed algorithm when compared with the Non-dominated Sorting Genetic Algorithm II and the latest Multi-objective Bee Colony Algorithm proposed to date.\",\n \"Title: Alternative Solutions for Distributed Simulation Cloning.\\nYear: 2003\\n\\nAbstract: Simulation cloning is designed to satisfy the requirement of examining alternative scenarios concurrently. This article discusses the issues involved in cloning distributed simulations based on the High Level Architecture (HLA) and proposes tentative solutions. Alternative solutions are compared from both the qualitative and quantitative point of view. In terms of federation organization, candidate solutions can be classified into the single-federation and the multiple-federation categories. To guarantee the correctness and optimize the performance of the whole cloning-enabled distributed simulation, the single-federation solution requires an additional mechanism to isolate the interactions among alternative executions. Data distribution management (DDM) is one of the candidate approaches. To measure the trade-off between complexity and efficiency, the authors introduce a series of experiments to benchmark various solutions at the runtime infrastructure (RTI) level. The benchmark results indicate that the single-federation solution provides encouraging performance when using DDM.\",\n \"Title: Key Message Algorithm: A Communication Optimization Algorithm in Cluster-Based Parallel Computing\\nYear: 1999\\n\\nAbstract: Parallel computing using Network of Workstations (NOWs) has become very popular recently. However, the execution of parallel applications on such systems has been hampered by the high communication overhead. To reduce the communication overhead and to speedup the execution of parallel applications on NOWs, this paper proposes a Key Message approach that minimizes the cost of message-passing in a parallel application by prioritizing communications in the underlying shared communication network. In this paper, we first describe the queuing network model on which our approach is based, then introduce the algorithm that identifies the messages to be prioritized in a parallel application, and finally discuss the results obtained. Our preliminary analysis of the algorithm on randomly generated task graphs shows improvement over the system without using the prioritization scheme.\",\n \"Title: Fair and Efficient Dead Reckoning-Based Update Dissemination for Distributed Virtual Environments\\nYear: 2012\\n\\nAbstract: Due to diverse network latencies, participants in a Distributed Virtual Environment (DVE) may observe different inconsistency levels of the simulated virtual world, which can seriously affect fair competition among them. In this paper, we investigate how to disseminate Dead Reckoning (DR)-based updates with the objectives of achieving fairness among participants and reducing inconsistency as much as possible. We first propose an optimized bandwidth allocation scheme for sending updates to overcome the drawbacks of uniform bandwidth allocation and the local-lag technique. Then, we integrate bandwidth allocation with an indirect relay method and develop algorithms to select relay routes for minimizing inconsistency under various bandwidth allocation schemes. Our proposed scheme and algorithms are evaluated using traces collected from a real car racing game as well as the real Internet latency data. The experimental results show that the proposed optimized bandwidth allocation scheme significantly reduces inconsistency while maintaining fairness among participants and that integrating the optimized scheme with our proposed relay setup algorithm further improves consistency.\",\n \"Title: A hybrid Interest Management mechanism for peer-to-peer Networked Virtual Environments\\nYear: 2010\\n\\nAbstract: An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Networked Virtual Environments (NVE). However, IM itself involves both computation and communication overhead, of which the latter is the focus of this paper. Traditionally, there are area-based and cell-based IM mechanisms. This paper proposes a hybrid IM mechanism for peer-to-peer NVEs, that utilizes the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism so as to reduce its communication overhead. To compare the new mechanism with the two traditional approaches, a multiplayer game scenario is simulated. The performance results show that, compared to the traditional mechanisms, the hybrid mechanism reduces the upload bandwidth consumption by more than 25.28 percent, reduces the overhead ratio from more than 67.54 percent to only 25.17 percent, and allows more than 5000 players in the Internet to join the same game with today's network upload bandwidth.\",\n \"Title: Benchmarking IBM SP1 system for SPMD programming\\nYear: 1996\\n\\nAbstract: The IBM SP1 is the first member of the IBM Scalable POWERparallel series, a distributed memory parallel computer based on RISC System/6000 processing element. In this paper, the benchmarking exercise of two message passing libraries, MPL and PVM, on the IBM SP1 for SPMD programming is described. We will discuss the benchmarks used in our experiment, and present the results we obtained. Our results indicate that to achieve performance improvement and to reduce the communication overhead, the use of the high performance switch is essential on the IBM SP1 machine\",\n \"Title: Spatial indexing in agent-based crowd simulation\\nYear: 2013\\n\\nAbstract: Crowd modeling and simulation has become a critical tool for understanding crowds and predicting their behaviours. This is accomplished by modelling the characteristics and behaviours of large groups of people, as well as their interactions. Agent-based crowd simulation may involve thousands of complex agents interacting in sophisticated ways, in close spatial proximity, with each other. A key challenge to the development of agent-based crowd simulation is the inherent complexity that is required to model all its necessary elements. A necessary feature of such a simulation is spatial indexing. This refers to the use of data structures to organize collections of simulation entities (e.g., agents and obstacles) in a manner which allows for efficient spatial querying. This is especially pertinent for large-scale crowd simulation with agents that sense their surrounding environment periodically, as the cost of spatial querying becomes computationally expensive if done naively. In this paper, we will describe our experience in improving the existing grid-based spatial indexing approach in our agent-based crowd simulation. Also, we will explore the integration of the adaptive spatial indices (e.g., R-tree and quad-tree) into our system. The performances of various spatial indexing techniques are examined in terms of efficiency and scalability.\",\n \"Title: Parallel distributed simulation and modeling methods: causal order based time warp: a tradeoff of optimism\\nYear: 2003\\n\\nAbstract: The optimistic synchronization paradigm, Time Warp, allows logical processes to advance aggressively. In the circumstances where the violation of the local causality constraint (LCC) is prone to occurring, this optimism may introduce substantial rollbacks and, as a consequence, significant overhead in recovering from erroneous computations. In this paper, a new approach, COBTW, is proposed, where the happen before relation is employed to capture the potential violations of LCC and causal order is applied to regulate the advancement of logical processes. Due to the difference between causal order and time-stamp order, there are discrepancies between them. Solutions to remove the discrepancies are proposed. Experiments conducted in a cluster and an emulated WAN suggest that COBTW reduces rollbacks caused by violations of LCC and empirically results in better performance, in comparison with the Time Warp protocol.\",\n \"Title: Performance Evaluation of a Bandwidth Requirements Reduction Technique Based on Timely State Update\\nYear: 2005\\n\\nAbstract: An important issue in distributed real-time simulation is to reduce the amount of data transmitted amongst distributed simulation nodes so that the state updates of simulation entities can be sent to other simulation nodes in a timely manner. To address this issue, we have previously proposed a consistency model to determine the update interval of entities based on their relative importance, a utility model to compute the relative importance of entities, and a flexible state update mechanism to ensure updating within these intervals and to balance the number of updates in each simulation frame. In this paper, we focus on the performance evaluation of these timely state update mechanisms. Using a battlefield benchmark, the performance is evaluated in terms of the total amount of data exchanged, the number of simulation frames skipped, and the number ofGo-Through-Accidents occurring during the simulation. The performance results indicate that the mechanisms can significantly reduce the bandwidth requirements while maintaining or even improving the consistency of the simulation.\",\n \"Title: Consistency Aware Dead Reckoning Threshold Tuning with Server Assistance in Client-Server-Based DVEs\\nYear: 2010\\n\\nAbstract: In distributed virtual environments (DVEs), maintaining a consistent view of the virtual world among all users is a primary task. Due to the resource limitations such as network capacity and computational power, the consistency of the virtual world cannot be guaranteed sometimes. In this paper, we try to address this problem in client-server-based DVEs by considering server side network capacity limitation. We look at the position update packets from client to server and show the impact of packet loss due to server side network capacity limitation on the consistency of the virtual world. We assume clients use Dead Reckoning (DR) models to control position updates. In order to adapt client updates with the server side network capacity to avoid update packet loss, two server assistant DR threshold tuning policies for different updating schemas are proposed in this paper. The proposed tuning polices are validated to have good performance by simulation results.\",\n \"Title: Load balancing for conservative simulation on shared memory multiprocessor systems\\nYear: 2000\\n\\nAbstract: Load balancing is a crucial factor in achieving good performance for parallel discrete event simulations. We present a load balancing scheme that combines both static partitioning and dynamic load balancing. The static partitioning scheme maps simulation objects to logical processes before simulation starts while the dynamic load balancing scheme attempts to balance the load during runtime. The static scheme involves two steps. First, the simulation objects that contribute to small lookahead are merged together by using a merging algorithm. Then a partitioning algorithm is applied. The merging is needed to ensure a consistent performance for our dynamic scheme. Our dynamic scheme is tailor-made for an asynchronous simulation protocol that does not rely on null messages. The performance study on a supply chain simulation shows that the partitioning algorithm and dynamic load balancing are important in achieving good performance\",\n \"Title: Shared Variable Management in SOAr-DSGrid\\nYear: 2008\\n\\nAbstract: Simulation is a low cost alternative to experimentation on real-world physical systems. In light of the prevalence of web services, issues relating to distributed simulation using web services have come to the fore in recent years. We have proposed a service-oriented architecture for distributed simulations on the Grid (SOAr-DSGrid). SOAr-DSGrid facilitates the development and execution of distributed simulations in different views (i.e., a component-based view for development and a service-oriented view for execution). At run time, one component may require information from another component for execution or decision-making. In SOAr-DSGrid, this shared information from one component to another component is implemented through shared variables. Since two components may execute out of phase, without proper shared variable management, the value provided by one component may be invalid for another component due to the time difference. Since SOAr-DSGrid provides a service-oriented view for component execution, the development of shared variable support also follows the service-oriented methodology. Three different approaches, namely Pull without FutureList, Pull with FutureList, and Push, have been implemented as the internal mechanism to solve the shared variable issue. Experimental results of the performance of these three approaches are also presented in this paper.\",\n \"Title: A systematic approach for rapid 3D reconstruction from photosets.\\nYear: 2010\\n\\nAbstract: We present an interactive framework for rapid 3D reconstruction of objects from sets of photographs. Our framework implements advanced 2D image-based modeling techniques that accurately compute geometries of digital photorealistic 3D models in a rapid and robust method. It is implemented in an application tool to assist users to perform feature detection, matching and meshing. Our system demonstrates that with a few user's intervention through our application tool, efficient generation of 3D object models can be generated from a set of photos.\",\n \"Title: Servicing Provisioning for HLA-Based Distributed Simulation on the Grid\\nYear: 2005\\n\\nAbstract: Modeling and simulation permeate all areas of business, science and engineering. With the increase in the scale and complexity of simulations, large amounts of computational resources are required, and provisioning of the services is becoming increasingly difficult. The Grid provides a platform for coordinated resource sharing and application development and execution. In this paper, we focus on extending the High Level Architecture (HLA) to the Grid. More specifically, we propose a distributed simulation framework, called HLAGrid. The framework uses a Federate-Proxy-RTI architecture, which allows resources on the Grid to be utilized on demand by using Grid services. The architecture also supports federation discovery, security of the simulator logic, and flexible federation construction, such as hierarchical federations. The architecture hides the heterogeneity of the simulators, simulatorsý execution platforms, and how the simulators communicate with the RTI. All interfaces used in the framework comply with the standard HLA interface specification, which provides reusability to simulators. A prototype of the framework is implemented using DMSOýs RTI 1.3NG version 6 and the Grid system runs the Globus Toolkit.\",\n \"Title: Improving performance by replicating simulations with alternative synchronization approaches\\nYear: 2008\\n\\nAbstract: Parallel and distributed simulation facilitates the construction of a simulation application (i.e., federation in HLA terminology) with a number of simulation components (federates). Recently, an approach based on active replication technique has been proposed to improve the performance of simulations by exploring software diversity. To guarantee the correctness of the approach, all replicas of the same federate are required to be Piece-Wise-Deterministic (PWD). However, the PWD restriction will not be satisfied if the replicas achieve software diversity by employing different kinds of synchronization approaches. A replication structure is proposed in this paper, which can transparently handle the federate replicas that use either conservative or optimistic synchronization approach. The execution speed of the federation is increased by always choosing the fastest replica to represent the federate in the federation. Besides presenting the implementation details, we also report the experimental results to demonstrate the performance improvement of the replication structure.\",\n \"Title: A Parallelism Analyzer Algorithm for a Conservative Super-Step Simulation Protocol\\nYear: 1999\\n\\nAbstract: Given an existing complex sequential simulation program, it is useful to have a parallelism analysis algorithm to quickly predict the corresponding parallel simulation program's performance. Wong et al. have described such an algorithm for the asynchronous Chandy-Misra-Bryant simulation protocol. This paper describes a parallelism analysis algorithm for a \\\"synchronous\\\\super-step\\\" protocol. We also discuss the assumptions needed in order for the prediction to be meaningful (i.e it should re ect at least one of the possible parallel runs), and the analyzer algorithm's correctness. Finally we will brie y discuss the algorithm modifications needed if we are to remove one of the assumptions.\",\n \"Title: Dead Reckoning-Based Update Scheduling against Message Loss for Improving Consistency in DVEs\\nYear: 2011\\n\\nAbstract: Maintaining a consistent presentation of the virtual world among participants is a fundamental problem in the Distributed Virtual Environment (DVE). The problem is exacerbated due to the limited network bandwidth and errorprone transmission. This paper investigates Dead Reckoning (DR) update scheduling to improve consistency in the DVE against message loss. Using the metric of Time-Space Inconsistency (TSI), which combines the spatial magnitude and temporal duration of inconsistency, we analytically derive the impact of message loss on TSI when using a DR-based update mechanism. To improve consistency against message loss, a naive update scheduling algorithm is first proposed, in which the expected spatial difference is calculated by taking message loss into account. In order to reduce the TSI to the case without transmission failures, a compensation update scheduling algorithm is further proposed by reducing the DR threshold according to the message loss rate. Using these algorithms, a budget-based mechanism is developed to meet the network bandwidth constraint. We show through experiments using a racing car game that the budget-based mechanism using the compensation update scheduling algorithm makes the best use of available network bandwidth to reduce the inconsistency and its impact on the participants. In addition, it ensures fairness among participants in spite of widely varying message loss rates.\",\n \"Title: Time-space consistency in large-scale distributed virtual environments\\nYear: 2004\\n\\nAbstract: Maintaining a consistent view of the simulated world among different simulation nodes is a fundamental problem in large-scale distributed virtual environments (DVEs). In this paper, we characterize this problem by quantifying the time-space inconsistency in a DVE. To this end, a metric is defined to measure the time-space inconsistency in a DVE. One major advantage of the metric is that it may be estimated based on some characteristic parameters of a DVE, such as clock asynchrony, message transmission delay, the accuracy of the dead reckoning algorithm, the kinetics of the moving entity, and human factors. Thus the metric can be used to evaluate the time-space consistency property of a DVE without the actual execution of the DVE application, which is especially useful in the design stage of a DVE. Our work also clearly shows how the characteristic parameters of a DVE are interrelated in deciding the time-space inconsistency, so that we may fine-tune the DVE to make it as consistent as possible. To verify the effectiveness of the metric, a Ping-Pong game is developed. Experimental results show that the metric is effective in evaluating the time-space consistency property of the game.\",\n \"Title: Symbiotic Simulation Control in Semiconductor Manufacturing\\nYear: 2008\\n\\nAbstract: Semiconductor manufacturing is a highly complex and asset intensive process. Solutions are needed to automate control of equipment and improve efficiency. We describe a symbiotic simulation control system which uses reactive what-if analysis to find a stable configuration of a wet bench tool set. This control system is based on a generic framework for symbiotic simulation. We show that symbiotic simulation can be used to make control decisions in near real-time. Furthermore, we show that our approach yields a notable performance improvement over common practise.\",\n \"Title: Analysis of an efficient rule-based motion planning system for simulating human crowds\\nYear: 2010\\n\\nAbstract: This paper proposes a rule-based motion planning system for agent-based crowd simulation, consisting of sets of rules for\\n both collision avoidance and collision response. In order to avoid an oncoming collision, a set of rules for velocity sampling\\n and evaluation is proposed, which aims to choose a velocity with an expected time to collision larger than a predefined threshold.\\n In order to improve the efficiency over existing methods, the sampling procedure terminates upon finding an appropriate velocity.\\n Moreover, the proposed motion planning system does not guarantee a collision-free movement. In case of collision, another\\n set of rules is also defined to direct the agent to make a corresponding response. The experiment results show that the proposed\\n approach can be applied in different scenarios, while making the simulation execution efficient.\",\n \"Title: Dag consistent parallel simulation: a predictable and robust conservative algorithm\\nYear: 1997\\n\\nAbstract: We present a novel approach to parallel discrete event simulation based on the Cilk model of multithreaded computation. Cilk's runtime system not only manages the low-level aspects of program execution, but also provides the user with an algorithmic model of performance which can be used to predict the execution time of a parallel simulation. Moreover, a Cilk application can ``scale down'' to run on a single processor with nearly the same performance as that of serial code.A conservative parallel discrete event simulation algorithm has been developed in which communication between logical processes is achieved using Cilk's virtual memory model, dag consistent shared memory. The simulation executes in cycles, where each cycle involves a divide and conquer computation. Although local lookahead information can be exploited, the algorithm is robust in that it also calculates a global simulation time for each cycle. It can therefore be used for applications where zero lookahead may occur.\",\n \"Title: Incremental HLA-based distributed simulation cloning\\nYear: 2004\\n\\nAbstract: Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same execution session. The goal is to optimize the execution time for evaluating different scenarios by avoiding repeated computation. In terms of High Level Architecture (HLA) based simulations, a federate may make clones to explore different scenarios at decision points. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected. This paper discusses the theory and issues involved in incremental distributed simulation cloning, which employs an event checking algorithm to ensure accurate sharing and initiates cloning only when absolutely necessary. Experiments have been performed to compare the performance of entire cloning and incremental cloning mechanisms. The experimental results indicate that cloning technologies can effectively reduce the time of executing multiple scenarios, and the incremental cloning mechanism significantly surpasses entire cloning in execution efficiency.\",\n \"Title: Evolving Optimal and Diversified Military Operational Plans for Computational Red Teaming\\nYear: 2012\\n\\nAbstract: Computational Red teaming (CRT) is a simulation-based optimization application utilized by defense analysts to uncover vulnerabilities of operational plans. In CRT, agent-based simulation models of military scenarios are automatically analyzed and modeled using evolutionary computation techniques. The CRT optimization process aims at identifying simulation models which exhibit emergent system behaviors of interest, e.g., when the adversary (called “Red”) breaks the defensive (“Blue”) strategies. Numerous multiobjective evolutionary algorithms (MOEAs) have been applied to CRT; however, the elitist and converging nature of these Pareto-based optimization algorithms typically leads to the generation of optimal, with respect to the Pareto front, but poorly diversified adversarial operational plans. As a result, the near-optimal alternative strategies are omitted; this considerably limits the applicability of CRT when considering the decision makers point of view. We propose a diversity enhancement scheme for MOEAs which uses the diversity contribution of individual solutions in the aggregated (combining both the objective and decision variable spaces) space to compute the fitness assignment. This feature enables both the exploitation of Pareto-optimal solutions whilst promoting diversification of the solutions in the decision variable space. Our experimental results indicate that this diversity enhancement mechanism can effectively resolve the diversification issue and, ultimately, enhance CRT to assist decision making.\",\n \"Title: A review of interactive narrative systems and technologies: a training perspective\\nYear: 2015\\n\\nAbstract: an emerging form of digital entertainment, the interactive narrative has attracted great attention from researchers over the past decade. Recently, there has been an emerging trend to apply interactive narratives to training and simulation. An interactive narrative system allows players to proactively interact with simulated entities in a virtual world and have the ability to alter the progression of a storyline. In simulation-based training, the use of an interactive narrative system enables the possibility to offer engaging, diverse and personalized narratives or scenarios for different training purposes. This paper provides a review of interactive narrative systems and technologies from a training perspective. Specifically, we first propose a set of key requirements in developing interactive narrative systems for simulation-based training. Then we review nine representative existing systems with respect to their system architectures, features and related mechanisms. To examine their applicability to training, we investigate and compare the reviewed systems based on the functionalities and modules that support the proposed requirements. Furthermore, we discuss some open research issues on the future development of interactive narrative technologies for training applications.\",\n \"Title: Let's depart together: Efficient play request dispatching in cloud gaming\\nYear: 2014\\n\\nAbstract: In this paper, we study the problem of how to dispatch the play requests to the cloud servers in a cloud gaming system. We show that the dispatching strategy of play requests may heavily affect the total service cost of the cloud gaming system. The play request dispatching problem can be considered as a variant of the dynamic bin packing problem. However, we show that the classical bin packing algorithms such as First Fit and Best Fit are not efficient in dispatching the play requests in cloud gaming due to the diurnal workload pattern of online games. To address this issue, we propose an efficient request dispatching algorithm that assigns the play requests according to the predicted ending times of the game sessions. Through extensive evaluations using real online gaming traces, we show that the proposed dispatching algorithm can significantly reduce the resource waste of the cloud servers and thus decrease the total service cost compared to the First Fit and Best Fit algorithms.\",\n \"Title: Self-Learning Gene Expression Programming\\nYear: 2016\\n\\nAbstract: In this paper, a novel self-learning gene expression programming (GEP) methodology named SL-GEP is proposed to improve the search accuracy and efficiency of GEP. In contrast to the existing GEP variants, the proposed SL-GEP features a novel chromosome representation where each chromosome is embedded with subfunctions that can be deployed to construct the final solution. As part of the chromosome, the subfunctions are self-learned or self-evolved by the proposed algorithm during the evolutionary search. By encompassing subfunctions or any partial solution as input arguments of another subfunction, the proposed SL-GEP facilitates the formation of sophisticated, higher-order, and constructive subfunctions that improve the accuracy and efficiency of the search. Further, a novel search mechanism based on differential evolution is proposed for the evolution of chromosomes in the SL-GEP. The proposed SL-GEP is simple, generic and has much fewer control parameters than the traditional GEP variants. The proposed SL-GEP is validated on 15 symbolic regression problems and six even parity problems. Experimental results show that the proposed SL-GEP offers enhanced performances over several state-of-the-art algorithms in terms of accuracy and search efficiency.\",\n \"Title: Dynamic Bin Packing for On-Demand Cloud Resource Allocation\\nYear: 2016\\n\\nAbstract: Dynamic Bin Packing (DBP) is a variant of classical bin packing, which assumes that items may arrive and depart at arbitrary times. Existing works on DBP generally aim to minimize the maximum number of bins ever used in the packing. In this paper, we consider a new version of the DBP problem, namely, the MinTotal DBP problem which targets at minimizing the total cost of the bins used over time. It is motivated by the request dispatching problem arising from cloud gaming systems. We analyze the competitive ratios of the modified versions of the commonly used First Fit, Best Fit, and Any Fit packing (the family of packing algorithms that open a new bin only when no currently open bin can accommodate the item to be packed) algorithms for the MinTotal DBP problem. We show that the competitive ratio of Any Fit packing cannot be better than + 1, where is the ratio of the maximum item duration to the minimum item duration. The competitive ratio of Best Fit packing is not bounded for any given . For First Fit packing, if all the item sizes are smaller than 1 of the bin capacity ( > 1 is a constant), the competitive ratio has an upper bound of 1 + 3 1 + 1. For the general case, the competitive ratio of First Fit packing has an upper bound of 2 + 7. We also propose a Hybrid First Fit packing algorithm that can achieve a competitive ratio no larger than 5 4 + 19 4 when is not known and can achieve a competitive ratio no larger than + 5 when is known.\",\n \"Title: Density-based evolutionary framework for crowd model calibration.\\nYear: 2015\\n\\nAbstract: Crowd modeling and simulation is an important and active research field, with a wide range of applications such as computer games, military training and evacuation modeling. One important issue in crowd modeling is model calibration through parameter tuning, so as to produce desired crowd behaviors. Common methods such as trial-and-error are time consuming and tedious. This paper proposes an evolutionary framework to automate the crowd model calibration process. In the proposed framework, a density-based matching scheme is introduced. By using the dynamic density of the crowd overtime, and a weight landscape to emphasize important spatial regions, the proposed matching scheme provides a generally applicable way to evaluate the simulated crowd behaviors. Besides, a hybrid search mechanism based on differential evolution is proposed to efficiently tune parameters of crowd models. Simulation results demonstrate that the proposed framework is effective and efficient to calibrate the crowd models in order to produce desired macroscopic crowd behaviors. (C) 2014 Elsevier B.V. All rights reserved.\",\n \"Title: Un-identical federate replication structure for improving performance of HLA-based simulations.\\nYear: 2014\\n\\nAbstract: •Propose an un-identical replication structure for improving performance of HLA-based simulations.•Use a middleware approach to support federate replication transparently.•Develop message exchange and time management mechanisms to handle different behaviors of un-identical replicas.•Provide correctness proof of the un-identical replication structure.•Achieve significant performance enhancement with good scalability and marginal overhead.\",\n \"Title: Hierarchical resource management for enhancing performance of large-scale simulations on data centers\\nYear: 2014\\n\\nAbstract: More and more interests have been shown to move large-scale simulations on modern data centers composed of a large number of virtualized multi-core computers. However, the simulation components (Federates) consolidated in the same computer may have imbalanced simulation workloads. Similarly, the computers involved in the same simulation execution (Federation) may also have imbalanced simulation workloads. Hence, federates may waste a lot of computer resources on time synchronization with each other. In this paper, a hierarchical resource management system is proposed to enhance simulation execution performance. Federates in the federation are enraptured in their individual Virtual Machines (VMs), which are consolidated on a group of virtualized multi-core computers. On the computer level, multiple VMs share the resource of the computer according to the simulation workloads of their corresponding federates. On the federation level, some VMs are migrated for workload balance purpose. Therefore, computer resources are fully utilized to conduct useful simulation workloads, avoiding the synchronization overheads. Experiments using synthetic and real simulation workloads have verified that the hierarchical resource management system enhances simulation performance significantly.\",\n \"Title: Efficient graph-based dynamic load-balancing for parallel large-scale agent-based traffic simulation\\nYear: 2014\\n\\nAbstract: One of the issues of parallelizing large-scale agent-based traffic simulations is partitioning and load-balancing. Traffic simulations are dynamic applications where the distribution of workload in the spatial domain constantly changes. Dynamic load-balancing at run-time has shown better efficiency than static partitioning in many studies. However, existing work has only focused on geographic partitioning methods which do not consider the minimization of communication overhead. In this paper, a graph-based dynamic load-balancing mechanism which minimizes the communication overhead during load-balancing operations is developed. Its efficiency is investigated in the agent-based traffic simulator SEMSim Traffic using real world traffic data. Experiment results show that it has significantly better performance than static graph partitioning methods in improving the overall speed of the simulation.\",\n \"Title: EA-based evacuation planning using agent-based crowd simulation\\nYear: 2014\\n\\nAbstract: Safety planning for crowd evacuation is an important and active research topic nowadays. One important issue is to devise the evacuation plans of individuals in emergency situations so as to reduce the total evacuation time. This paper proposes a novel evolutionary algorithm (EA)-based methodology, together with agent-based crowd simulation, to solve the evacuation planning problem. The proposed method features a novel segmentation strategy which divides the entire evacuation region into sub-regions based on a discriminant function. Each sub-region is assigned with an exit gate, and individuals in a sub-region will run toward the corresponding exit gate for evacuation. In this way, the evacuation planning problem is converted to a symbolic regression problem. Then an evolutionary algorithm, using agent-based crowd simulation as fitness function, is developed to search for the global optimal solution. The simulation results on different scenarios demonstrate that the proposed method is effective to reduce the evacuation time.\",\n \"Title: Evolving Agent-based Models Using Complexification Approach.\\nYear: 2014\\n\\nAbstract: This paper focuses on parameter search for multi-agent based models using evolutionary algorithms. Large numbers and variable dimensions of parameters require a search method which can efficiently handle a high dimensional search space. We are proposing the use of complexification as it emulates the natural way of evolution by starting with a small constrained search space and expanding it as the evolution progresses. We examined the effects of this method on an EA by evolving parameters for two multi-agent based models.\",\n \"Title: On dynamic bin packing for resource allocation in the cloud\\nYear: 2014\\n\\nAbstract: Dynamic Bin Packing (DBP) is a variant of classical bin packing, which assumes that items may arrive and depart at arbitrary times. Existing works on DBP generally aim to minimize the maximum number of bins ever used in the packing. In this paper, we consider a new version of the DBP problem, namely, the MinTotal DBP problem which targets at minimizing the total cost of the bins used over time. It is motivated by the request dispatching problem arising in cloud gaming systems. We analyze the competitive ratios of the commonly used First Fit, Best Fit, and Any Fit packing (the family of packing algorithms that open a new bin only when no currently opened bin can accommodate the item to be packed) algorithms for the MinTotal DBP problem. We show that the competitive ratio of Any Fit packing cannot be better than the max/min item interval length ratio μ. The competitive ratio of Best Fit packing is not bounded for any given μ. For First Fit packing, if all the item sizes are smaller than W⁄k (W is the bin capacity and k≥1 is a constant), it has a competitive ratio of k⁄k-1μ + 6k⁄k-1 + 1. For the general case, First Fit packing has a competitive ratio of 2μ + 13. We also propose a Modified First Fit packing algorithm that can achieve a competitive ratio of 8⁄7μ + 55⁄7 when μ is not known and can achieve a competitive ratio of μ + 8 when μ is known.\",\n \"Title: High-dimensional objective-based data farming\\nYear: 2011\\n\\nAbstract: In objective-based data farming, decision variables of the Red Team are evolved using evolutionary algorithms such that a series of rigorous Red Team strategies can be generated to assess the Blue Team's operational tactics. Typically, less than 10 decision variables (out of 1000+) are selected by subject matter experts (SMEs) based on their past experience and intuition. While this approach can significantly improve the computing efficiency of the data farming process, it limits the chance of discovering “surprises” and moreover, data farming may be used only to verify SMEs' assumptions. A straightforward solution is simply to evolve all Red Team parameters without any SME involvement. This modification significantly increases the search space and therefore we refer to it as high-dimensional objective-based data farming (HD-OBDF). The potential benefits of HD-OBDF include: possible better performance and information about more important decision variables. In this paper, several state-of-the-art multi-objective evolutionary algorithms are applied in HD-OBDF to assess their suitability in terms of convergence speed and Pareto efficiency. Following that, we propose two approaches to identify dominant/key evolvable parameters in HD-OBDF - decision variable coverage and diversity spread.\",\n \"Title: Map stream: Initializing what-if analyses for real-time symbiotic traffic simulations\\nYear: 2014\\n\\nAbstract: In the context of a city-scale symbiotic traffic simulation, real-time data about the location of many vehicles are obtained in the form of a continuous data-stream. In this paper, we present a scalable solution for performing map-matching using sliding-windows over a GPS data-stream onto a digital road network for initializing the what-if analysis process involved in symbiotic simulations. We focus on the optimizations performed to ensure that the latency associated with the map-matching process is low while maintaining a high degree of accuracy. Experimental results reveal the range in terms of sampling interval and noise for acceptable reliability and latency.\",\n \"Title: Adapting a supply-chain simulation for HLA\\nYear: 2000\\n\\nAbstract: Supply-chain management covers the planning and management of material and information from the manufacturer, through the distributors, and finally to the customer. With the globalization of markets, the optimization of supply-chain management becomes increasingly important. Simulation of supply-chains can help in the optimization process by evaluating the impact of alternative policies. To support the reusability of existing simulation models in a supply-chain simulation, a common standard is required for enabling the interoperability amongst different simulation programs through a well-defined interface. The High Level Architecture (HLA) is architecture for reuse and interoperation of simulations. This paper reports our experiences on employing the HLA to support reusability and interoperability in semiconductor supply-chain simulation. Our experiments show that by fine-tuning the integration of the application with the HLA Run-Time Infrastructure (RTI), considerable performance improvements can be achieved.\",\n \"Title: Emergence by strategy: Flocking boids and their fitness in relation to model complexity\\nYear: 2013\\n\\nAbstract: In this paper we aim to examine emergent properties of agent-based models by using evolutionary algorithms. Taking the model of flocking boids as an example, we study and try to understand how the pressure of natural selection towards strategic behavior can result in emergent behavior. Furthermore we investigate how an increase of complexity in the model affects those properties and discover some counter-intuitive behavior in the process.\",\n \"Title: Consistency-Aware Zone Mapping and Client Assignment in Multi-Server Distributed Virtual Environments\\nYear: 2015\\n\\nAbstract: In Distributed Virtual Environments (DVEs), the primary task is to maintain a consistent view of the virtual world among all users. Multi-server architecture has been shown to have good scalability to support a large population of users in DVEs. In the zone-based Multi-server Distributed Virtual Environment (MSDVE), zone mapping and client assignment are two key issues in the design of an efficien...\",\n \"Title: Differential evolution with sensitivity analysis and the Powell's method for crowd model calibration\\nYear: 2015\\n\\nAbstract: This paper proposes a novel evolutionary algorithm named differential evolution with sensitivity analysis and the Powell's method (DESAP) for model calibration. The proposed DESAP owns three main features. First, an entropy-based sensitivity analysis operation is introduced to dynamically identify important parameters of the model as evolution progresses online. Second, the Powell's method is performed periodically to fine-tune the important parameters of the best individual in the population. Finally, in each generation, the evolutionary operators are performed on a small number of better individuals in the population. These new search mechanisms are integrated into the differential evolution framework to improve the search efficiency. To validate its effectiveness, the proposed DESAP is applied to two crowd model calibration cases. The results demonstrate that the proposed DESAP outperforms several model calibration methods in terms of solution accuracy and search efficiency. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.\",\n \"Title: Evolving agent-based models using self-adaptive complexification\\nYear: 2015\\n\\nAbstract: This paper focuses on parameter search for multi-agent based models using evolutionary algorithms. Large numbers and variable dimensions of parameters require an optimization method which can efficiently handle a high dimensional search space. We are proposing the use of complexification as it emulates the natural way of evolution by starting with a small constrained search space and expanding it as the evolution progresses. To further improve performance we suggest and experiment with methods of self-adaptation to enable the algorithm to adjust its parameters individually to the problem at hand. We examined the effects of these methods on an EA by evolving parameters for two multi-agent based models. (C) 2015 Elsevier B.V. All rights reserved.\",\n \"Title: Effects of topology and buffering on a processor farm\\nYear: 1999\\n\\nAbstract: The advantages of a processor farm include dynamic load balancing and low-complexity implementation. The major disadvantage is work starvation. Research has proposed different application-specific or platform-specific models of a processor farm. Few have attempted to study the performance characteristics of a processor farm model under varying system parameters. In this paper, we present the design of a distributed-memory processor farm with a topology-independent communications process architecture which offers reduced work starvation by providing minimal routes for work dissemination and results acknowledgment. We evaluate its performance characteristics under varying network size, topology and buffer requirements.\",\n \"Title: Play Request Dispatching for Efficient Virtual Machine Usage in Cloud Gaming\\nYear: 2015\\n\\nAbstract: Cloud gaming is becoming increasingly popular. The basic idea of cloud gaming is to run games on cloud servers and let players interact with games through thin clients. As the player population grows, the cloud gaming service provider needs to maintain a large number of cloud servers for running the game instances requested by the players. A primary concern of the cloud gaming service provider is ...\",\n \"Title: Transparent three-phase Byzantine fault tolerance for parallel and distributed simulations.\\nYear: 2016\\n\\nAbstract: •Propose a three-phase Byzantine Fault Tolerance (BFT) mechanism.•Integrate replication, checkpointing and message logging techniques.•Develop the BFT mechanism in a transparent manner.•Remove epidemic effects of Byzantine failures.•Evaluate the BFT mechanism using a real-world simulation model.\",\n \"Title: SEMSim Cloud Service: Large-scale urban systems simulation in the cloud\\nYear: 2015\\n\\nAbstract: Large-scale urban systems simulations are complex and with a large number of active simulation entities the computational workload is extensive. Workstation computers have only limited capabilities of delivering results for large-scale simulations. This leads to the problem that many researchers and engineers have to either reduce the scope of their experiments or fail to execute as many experiments as they would like in a given time frame. The use of high-performance computing (HPC) infrastructure offers a solution to the problem. Users of such simulations are often domain experts with no or little experience with HPC environments. In addition users do not necessarily have access to an HPC. In this paper we propose an architecture for a cloud-based urban systems simulation platform which specifically aims at making large-scale simulations available to typical users. The proposed architecture also addresses the issue of data confidentiality. In addition we describe the Scalable Electro-Mobility Simulation (SEMSim) Cloud Service that implements the proposed architecture.\",\n \"Title: An Asynchronous Synchronization Strategy for Parallel Large-scale Agent-based Traffic Simulations\\nYear: 2015\\n\\nAbstract: Large-scale agent-based traffic simulation is a promising tool to study the road traffic and help solving traffic problems, such as congestion and high emission in megacities. Such simulation requires high computational resource which triggers the need for parallel computing. The parallelization of agent-based traffic simulations is generally performed by decomposing the simulation space into spatial subregions. The agent models contained by each subregion are executed by Logical Processes (LPs). As the simulated system evolves over the simulation time in individual LPs, synchronization among LPs is required due to data dependencies. Existing work has used global barriers for synchronization which is a type of synchronous synchronization method. However, global barriers have very low efficiency due to the waiting of processes at barriers. High synchronization overhead is still one of the major performance issues in parallel large-scale agent-based traffic simulations. In this paper, we proposed a novel asynchronous conservative synchronization strategy named Mutual Appointment (MA) to address this issue. MA removes global barriers and allows LPs to communicate individually. Since the efficiency of conservative synchronization relies on the lookahead of the simulated system, a heuristic was developed to increase the lookahead in agent-based traffic simulations. It takes advantage of the intrinsic uncertainties in traffic simulations. MA together with the lookahead heuristic forms the Relaxed Mutual Appointment (RMA) strategy. Its efficiency was investigated in the parallel agent-based traffic simulator SEMSim Traffic using real world traffic data. Experiment results showed that the MA strategy improved the speed-up of the parallel simulation compared to the barrier method, and the RMA strategy further improved the MA strategy by reducing the number of synchronization messages significantly.\",\n \"Title: Traffic Simulation Performance Optimization through Multi-Resolution Modeling of Road Segments\\nYear: 2015\\n\\nAbstract: In an agent-based traffic simulation the level of detail is crucial to the system's runtime performance as well as the fidelity of the results. Therefore, different model abstractions have been used throughout literature. Macroscopic, mesoscopic and microscopic models have their use-cases and benefits. Microscopic traffic simulations have a high level of detail but at the same time require a large amount of computational resources. In a large traffic network of a mega-city or an entire country, the use of a complete microscopic simulation is just not feasible. The resource required to do so are for most use-cases in no relation to the actual outcome. We propose a hybrid traffic simulation model that uses both, a high-resolution agent based microscopic simulation alongside a lower resolution flow-based macroscopic simulation for specific road segments. The problem with using different simulation models is the fidelity at the boundary between such simulation models. This fidelity discrepancy is caused by the difficulties with aggregation and disaggregation passing through the boundary. We show, in this paper, that the computational performance (simulation time) can be improved by $20\\\\\\\\%$ while maintaining a relative high accuracy of below $5\\\\\\\\%$ deviation from a pure microscopic simulation.\",\n \"Title: Cloning Agent-based Simulation on GPU\\nYear: 2015\\n\\nAbstract: Simulation cloning is an efficient way to analyze multiple configurations in a parameter exploration task. This paper presents a generic approach to perform incremental agent-based simulation cloning and discusses its implementation on GPU. Compared with the incremental cloning of parallel and distributed simulation (PADS), cloning agent-based simulation (ABS) has new challenges due to the unique way how ABS is executed. In this paper, to support incremental cloning, mechanisms for both actively and passively cloning agents are proposed. A scheme to maintain the correct context of each cloned ABS instance is developed. In addition, a strategy to restrain the propagation of passive cloning in order to maximize computation sharing amongst cloned ABS instances is also investigated. The implementation of our proposed approach on GPU supports concurrent execution of agents within each simulation instance as well as concurrent execution of multiple simulation instances. Performance of the proposed approach is evaluated and analyzed using a case study of an agent-based evacuation simulation on a NVIDIA Quadro 2000 GPU. Our experiment results demonstrate that cloning can significantly speed up the overall parameter exploration task. The proposed approach achieves 2.4 to 5.1 times speedup for parameter exploration tasks containing 8 to 125 simulation instances that evaluate different parameter configurations.\",\n \"Title: A data-driven approach for online adaptation of game difficulty\\nYear: 2015\\n\\nAbstract: Dynamic adaptation of games with the objective of catering to the individual players' level of standard is an emerging and challenging research area of artificial intelligence in digital game. In this paper, we propose a data-driven approach for dynamic adaptation of game scenario difficulties. The goal is to fit the performance of the player to the desired conditions set by the designer. To this end, the data on player's in-game performance and dynamic game states are utilized for making adaptation decisions. Trained artificial neural networks are used to capture the relationship between dynamic game state, player performance, adaptation decision and the resultant game difficulty. Based on the predicted difficulty, adaptation of both direction and magnitude can be performed more effectively. Experimental study on a training game application is presented to demonstrate the efficiency and stability of the proposed approach.\",\n \"Title: Learning Behavior Patterns from Video: A Data-driven Framework for Agent-based Crowd Modeling\\nYear: 2015\\n\\nAbstract: This paper proposes a generic data-driven crowd modeling framework to generate crowd behaviors that can match the video data. The proposed framework uses a dual-layer mechanism to model the crowd behaviors. The bottom layer models the microscopic collision avoidance behaviors, while the top layer models the macroscopic crowd behaviors such as the goal selection patterns and the path navigation patterns. Based on the dual-layer mechanism, an automatic learning method is proposed to learn the model components from video data. To validate its effectiveness, the proposed framework is applied to generate the crowd behaviors in New York Grand Central Terminal. The simulation results demonstrate that the proposed method is able to construct effective model that can generate the desired emergent crowd behaviors and can offer promising prediction performance.\",\n \"Title: Efficient Neighbor Searching for Agent-Based Simulation on GPU\\nYear: 2014\\n\\nAbstract: This paper introduces a strategy to accelerate neighbor searching in agent-based simulations on GPU platforms. Because of their autonomous nature, agents can be processed by threads concurrently on GPU, and the overall simulation can be accelerated consequently. Each agent will simultaneously carry out a sense-think-act cycle in every time step. The neighbor searching is a crucial part in the sensing stage. Detecting and accessing neighbors is a memory intensive task and often becomes the major time consumer in an agent-based simulation. Our contribution, an enhanced neighbor sharing strategy, greatly speeds up this procedure when comparing with CPU implementations. The strategy is developed from a global-memory-only implementation, and then gradually improved by efficiently utilizing the much faster shared memory. In our case studies, speedups of 89.08 and 11.51 are obtained on an NVIDIA Tesla K20 GPU compared with the sequential implementation and OpenMP parallel implementation respectively on an Intel Xeon E5-2670 CPU.\",\n \"Title: Evaluation of Crowd Models in Low Density Scenarios Using Real-World Crowd Data.\\nYear: 2015\\n\\nAbstract: In this paper, we evaluate the simulation accuracy of five crowd models: (a) RVO2; (b) social force; (c) approximate nearest neighbor search (ANN); (d) perception-action graph (PAG); and (e) clustering-based model (CLUST) by comparing the simulation results against the real world motion data quantitatively on six metrics: (a) travel time; (b) travel distance; (c) deviation; (d) speed change; (e) angle change; and (f) energy. We use real pedestrians' motion data in two scenarios with different crowd densities and main walking directions as the ground truth. The results demonstrate that the CLUST model outperforms other models in terms of most metrics, while the PAG model has the worst accuracy in all metrics. The performance of the social force model depends largely on the scenario. We also conduct a qualitative comparison of five models on a simple scenario with only two agents, in order to give an indication of the differences and similarities between models. We find that the simulated trajectories of the RVO2 and social force models are more symmetric and regular than that generated by the ANN, PAG and CLUST models. And the ANN, PAG and CLUST models' trajectories reflect the motion behaviors of the input data used to train the models. Finally, we compare the simulation frame rates of five models on two real-world scenarios and show that by applying certain data pre-processing techniques, the PAG and CLUST models can achieve better run-time performances than the ANN model, but still run slower than the RVO2 and social force models.\",\n \"Title: MASTER: Multi-platform Application Streaming Toolkits for Elastic Resources\\nYear: 2015\\n\\nAbstract: In this demonstration, we propose MASTER, a set of toolkits for cross-platform application streaming that is able to utilize elastic resources on public clouds. MASTER has many useful features. It provides full control of resource acquisition and request dispatching, requires only a browser on the client side for user interactions, and incorporates an input transformer to assist touchscreen device users to naturally interact with desktop applications that need keystroke and mouse control. MASTER also supports session concurrency (serving multiple streaming sessions on a single cloud server instance), thereby improving resource utilization and cutting the cloud bill.\",\n \"Title: Crowd evacuation planning using cartesian genetic programming and agent-based crowd modeling.\\nYear: 2015\\n\\nAbstract: This paper proposes a new evolutionary algorithm-based methodology for optimal crowd evacuation planning. In the proposed methodology, a heuristic-based evacuation scheme is firstly introduced. The key idea is to divide the region into a set of sub-regions and use a heuristic rule to dynamically recommend an exit to agents in each sub-region. Then, an evolutionary framework based on the Cartesian Genetic Programming algorithm and an agent-based crowd simulation model is developed to search for the optimal heuristic rule. By considering dynamic environment features to construct the heuristic rule and using multiple scenarios for training, the proposed methodology aims to find generic and efficient heuristic rules that perform well on different scenarios. The proposed methodology is applied to guide people's evacuation behaviors in six different scenarios. The simulation results demonstrate that the heuristic rule offered by the proposed method is effective to reduce the crowd evacuation time on different scenarios.\",\n \"Title: Tutorial on a modeling and simulation cloud service.\\nYear: 2015\\n\\nAbstract: For large-scale urban system simulations the computing power of traditional workstations is not sufficient. The move to High Performance Computing clusters is a viable solution. Users of such simulations are domain experts with little knowledge in computer science and optimization of such simulations. The access to HPC resources is also not available. Vendors have not sufficiently addressed this. This leads to the conclusion of moving the computational demand to the cloud, where the on-demand culture for resources has been expanding. In this tutorial we will present an approach of how to work with an entirely cloud-based solution for modeling and simulation, with an exemplary implementation of an urban traffic simulation cloud service. Since the computational offload from the workstation to a remote computing entity also allows the use of novel user interfaces (design and devices), through the use of RESTful interfaces, use-case applicable interfaces for simulations can also be created.\",\n \"Title: Design of supply chain topology to mitigate demand and supply risks.\\nYear: 2015\\n\\nAbstract: To achieve competitive advantage, companies have been driven to improve their supply chain by outsourcing their non-core business. However, this increases the external risks, such as the demand and supply risks. Companies face challenges in defining effective supply chain topology to mitigate supply chain risks. In this research, we design supply chain network topologies to mitigate the demand and supply risks. Four supply chain network topologies have been designed to represent different supply chain strategies: efficient, responsive, risk-hedging, and agile strategies. An agent-based modeling approach is proposed to evaluate the performance of the supply chain network topologies under different demand and supply risk scenarios. From the results, we can identify the effective supply chain network topology to mitigate the disruption for a particular risk scenario.\",\n \"Title: Trusted Block as a Service: Towards Sensitive Applications on the Cloud\\nYear: 2011\\n\\nAbstract: Cloud computing grows rapidly as today's advanced information technology. However, by allowing outsourcing computation on the Cloud, users risk of disclosing privacy and obtaining forged results. These potential threats block sensitive applications to join the Cloud. In this paper, we characterize sensitive applications on the Cloud (SAND) problem and define two critical security requirements: confidentiality and verifiability. The former refers to the protection of sensitive programs/data from disclosing to other users or even the Cloud administrators. The latter concerns with user's capability to verify whether computing results are faithfully calculated. To address SAND, we propose a new Cloud model, Trusted Block as a Service (TBaaS), to provide a confidential and verifiable environment for each sensitive application. TBaaS limits Cloud provider's access of sensitive applications while granting user the ability to verify whether the computation is faithfully carried out. Moreover, it offers high flexibility and low performance overhead.\",\n \"Title: Data-Driven Dynamic Adaptation Framework for Multi-agent Training Game.\\nYear: 2015\\n\\nAbstract: In this paper, we present a dynamic adaptation framework to adapt the game scenarios for a multi-agent training game. We consider the problem where a trainee has to practice along multiple objectives during the training, and each objective is assigned with a desired difficulty level. The proposed dynamic adaptation approach takes into account of individual player's playing ability as well as the dynamic game circumstance to determine how to adapt the game scenario. We utilize artificial neural networks to construct a data-driven prediction model to estimate the effect of taking certain adaptation to the game. Based on the prediction model, our adaptation framework can determine both the direction and quantity of the adaptation. The performance of the proposed framework is testified in a food distribution training game and the results demonstrate the effectiveness of our adaptation framework.\",\n \"Title: Supporting efficient execution of continuous space agent-based simulation on GPU.\\nYear: 2016\\n\\nAbstract: Using agent-based simulation ABS to analyze complex adaptive systems gains growing popularity over the past decades. One of the fundamental issues in ABS is to increase the execution speed. In this paper, we identify two common modules that widely exist in ABS applications, namely, the agent management module and the agent interaction module. Improving the efficiency of these two common modules can significantly speed up the ABS execution in general. GPU architecture, programming model, and memory hierarchy are studied. Effective strategies on GPU are proposed when we design the two modules. The first contribution of this work is to propose an AgentPool data structure to handle agent creation and deletion on GPU. The second contribution is an efficient agent interaction module, which is designed by carefully utilizing the GPU memory hierarchy. To demonstrate effectiveness and generality, the proposed strategies are applied to a range of ABS applications, including game-of-life, flocking boids, prey-and-predator, and the social force-based crowd simulation. The simulation results demonstrate that the proposed strategies achieve better performance than the commonly used CPU and GPU ABS framework, namely, Mason and FLAME, for ABS applications using continuous space. Copyright © 2016 John Wiley & Sons, Ltd.\",\n \"Title: Learning behavior patterns from video for agent-based crowd modeling and simulation.\\nYear: 2016\\n\\nAbstract: This paper proposes a novel data-driven modeling framework to construct agent-based crowd model based on real-world video data. The constructed crowd model can generate crowd behaviors that match those observed in the video and can be used to predict trajectories of pedestrians in the same scenario. In the proposed framework, a dual-layer architecture is proposed to model crowd behaviors. The bottom layer models the microscopic collision avoidance behaviors, while the top layer models the macroscopic crowd behaviors such as the goal selection patterns and the path navigation patterns. An automatic learning algorithm is proposed to learn behavior patterns from video data. The learned behavior patterns are then integrated into the dual-layer architecture to generate realistic crowd behaviors. To validate its effectiveness, the proposed framework is applied to two different real world scenarios. The simulation results demonstrate that the proposed framework can generate crowd behaviors similar to those observed in the videos in terms of crowd density distribution. In addition, the proposed framework can also offer promising performance on predicting the trajectories of pedestrians.\",\n \"Title: A Role-dependent Data-driven Approach for High Density Crowd Behavior Modeling.\\nYear: 2016\\n\\nAbstract: In this paper, we propose a role-dependent data-driven modeling approach to simulate pedestrians' motion in high density scenes. It is commonly observed that pedestrians behave quite differently when walking in dense crowd. Some people explore routes towards their destinations. Meanwhile, some people deliberately follow others, leading to lane formation. Based on these observations, two roles are included in the proposed model: leader and follower. The motion behaviors of leader and follower are modeled separately. Leaders' behaviors are learned from real crowd motion data using state-action pairs while followers' behaviors are calculated based on specific targets that are obtained dynamically during the simulation. The proposed role-dependent data-driven model is trained on crowd video data in one dataset and is then applied to two other different datasets to test its generality and effectiveness. The simulation results demonstrate that the proposed role-dependent data-driven model is capable of simulating crowd behaviors in crowded scenes realistically and reproducing collective crowd behaviors such as lane formation.\",\n \"Title: Online Data Extraction for Large-Scale Agent-Based Simulations.\\nYear: 2016\\n\\nAbstract: Cloud-based simulation systems reduce the upfront hardware costs of running high-performance experiments and increases the ease with which simulation experiments can be repeated. The data being generated by simulations can be large. Commonly used data storage systems such as relational databases can handle large amounts of data, but the analysis is a challenging problem. Moreover, handling this amount of data in cloud services can be both expensive (bandwidth and storage costs) and time-consuming. However, a lot of the data that is generated by agent-based simulations does not contribute directly to the purpose of the experiment being conducted. We propose an extension to cloud-based simulation systems that rather than storing raw simulation output data, uses stream data processing to generate the result dataset while the simulation is running. This can then be used to store only the data required for later use, this saving both time and money.\",\n \"Title: A Hyper-Heuristic Framework for Agent-Based Crowd Modeling and Simulation: (Extended Abstract).\\nYear: 2016\\n\\nAbstract: This paper proposes a hyper-heuristic crowd modeling framework to generate realistic crowd dynamics that can match video data. In the proposed framework, motions of agents are driven by a high-level heuristic (HH) which intelligently selects way-points for agents based on the current situations. Three low-level heuristics are defined and used as building blocks of the HH. Based on the newly defined building blocks and fitness evaluation function, the Self-Learning Gene Expression Programming (SL-GEP) is utilized to automatically evolve a suitable HH. To test its effectiveness, the proposed framework is applied to learn suitable HHs based on real video data. The best HH learned is then applied to generate crowd simulations and the simulation results demonstrate that the proposed method is effective to generate realistic crowd dynamics.\",\n \"Title: On First Fit Bin Packing for Online Cloud Server Allocation\\nYear: 2016\\n\\nAbstract: Cloud-based systems often face the problem of dispatching a stream of jobs to run on cloud servers in an online manner. Each job has a size that defines the resource demand for running the job. Each job is assigned to run on a cloud server upon its arrival and the job departs after it completes. The departure time of a job, however, is not known at the time of its arrival. Each cloud server has a fixed resource capacity and the total resource demand of all the jobs running on a server cannot exceed its capacity at all times. The objective of job dispatching is to minimize the total cost of the servers used, where the cost of renting each cloud server is proportional to its running hours by \\\"pay-as-you-go\\\" billing. The above job dispatching problem can be modeled as a variant of the Dynamic Bin Packing (DBP) problem known as MinUsageTime DBP. In this paper, we develop new approaches to the competitive analysis of the commonly used First Fit packing algorithm for the MinUsageTime DBP problem, and establish a new upper bound of μ+4 on the competitive ratio of First Fit packing, where μ is the ratio of the maximum job duration to the minimum job duration. Our result significantly reduces the gap between the upper and lower bounds for the MinUsageTime DBP problem to a constant value independent of μ, and shows that First Fit packing is near optimal for MinUsageTime DBP.\",\n \"Title: Traffic State Estimation Using Floating Car Data.\\nYear: 2016\\n\\nAbstract: There is an increasing availability of floating car data both historic, in the form of trajectory datasets and real-time, in the form of continuous data streams. This paves the way for several advanced traffic management services such as current traffic state estimation, congestion and incident detection and prediction of the short-term evolution of traffic flow. In this paper, we present an analysis of using probe vehicles for reconstructing traffic state. We employ detailed agent-based microscopic simulations of a real world expressway to estimate the state from floating car data. The probe penetration required for accurate traffic state estimation is also determined.\",\n \"Title: Adaptive Resilient Strategies For Supply Chain Networks\\nYear: 2016\\n\\nAbstract: Due to globalization of economy, the supply chains are vulnerable to disruptive events. In addition, lean initiatives often lead to single supplier, which is vulnerable to supply disruption. In this paper, two strategies are proposed for generating supply chain networks to improve the resilience of supply chain networks: hierarchical preferential attachment and hierarchical random attachment. The supply chain resilience is evaluated using supply availability and the demand to supply ratio. Disruptions in the supply chain are modeled using random and targeted disruptions. The paper also designed an algorithm to recover the supply chain network from disruptions, based on the network attachment rules (preferential attachment and random attachment). Through a simulation study, the recovered supply chain is shown to have better resilience compared to a single supplier supply chain network.\",\n \"Title: Server Allocation for Multiplayer Cloud Gaming.\\nYear: 2016\\n\\nAbstract: Advances in cloud computing and GPU virtualization are allowing the game industry to move into a cloud gaming era. While shifting standalone video games to the cloud gaming mode is straightforward, adapting multiplayer online games to the cloud gaming paradigm faces unique challenges. In this paper, we consider multiplayer cloud gaming (MCG), which is the natural integration of multiplayer online gaming and cloud gaming paradigms. We formulate an MCG server allocation problem with the objective of minimizing the total server rental and bandwidth cost charged by the cloud to support an MCG session. We propose several efficient heuristics to address the MCG server allocation problem which is hard to solve optimally. We conduct extensive experiments using real Internet latency and cloud pricing data to evaluate the effectiveness of our proposed algorithms as well as several alternatives. Experimental results show that our best algorithm can achieve near-optimal cost under real-time latency constraints.\",\n \"Title: IBED: Combining IBEA and DE for optimal feature selection in software product line engineering.\\nYear: 2016\\n\\nAbstract: Abstract Software configuration, which aims to customize the software for different users (e.g., Linux kernel configuration), is an important and complicated task. In software product line engineering (SPLE), feature oriented domain analysis is adopted and feature model is used to guide the configuration of new product variants. In SPLE, product configuration is an optimal feature selection problem, which needs to find a set of features that have no conflicts and meanwhile achieve multiple design objectives (e.g., minimizing cost and maximizing the number of features). In previous studies, several multi-objective evolutionary algorithms (MOEAs) were used for the optimal feature selection problem and indicator-based evolutionary algorithm (IBEA) was proven to be the best MOEA for this problem. However, IBEA still suffers from the issues of correctness and diversity of found solutions. In this paper, we propose a dual-population evolutionary algorithm, named IBED, to achieve both correctness and diversity of solutions. In IBED, two populations are individually evolved with two different types of evolutionary operators, i.e., IBEA operators and differential evolution (DE) operators. Furthermore, we propose two enhancement techniques for existing MOEAs, namely the feedback-directed mechanism to fast find the correct solutions (e.g., solutions that satisfy the feature model constraints) and the preprocessing method to reduce the search space. Our empirical results have shown that IBED with the enhancement techniques can outperform several state-of-the-art MOEAs on most case studies in terms of correctness and diversity of found solutions.\",\n \"Title: Sampling-based adaptive bounding evolutionary algorithm for continuous optimization problems.\\nYear: 2017\\n\\nAbstract: This paper proposes a novel sampling-based adaptive bounding evolutionary algorithm termed SABEA that is capable of dynamically updating the search space during the evolution process for continuous optimization problems. The proposed SABEA adopts two bounding strategies, namely fitness-based bounding and probabilistic sampling-based bounding, to select a set of individuals over multiple generations and leverage the value information from these individuals to update the search space of a given problem for improving the solution accuracy and search efficiency. To evaluate the performance of this method, SABEA is applied on top of the classic differential evolution (DE) algorithm and a DE variant, and SABEA is compared to a state-of-the-art Distribution-based Adaptive Bounding Genetic Algorithm (DABGA) on a set of 27 selected benchmark functions. The results show that SABEA can be used as a complementary strategy for further enhancing the performance of existing evolutionary algorithms and it also outperforms DABGA. Finally, a practical problem, namely the model calibration for an agent-based simulation, is used to further evaluate SABEA. The results show SABEA’s applicability to diverse problems and its advantages over the traditional genetic algorithm-based calibration method and DABGA.\",\n \"Title: Predicting The Duration Of Non-Recurring Road Incidents By Cluster-Specific Models\\nYear: 2016\\n\\nAbstract: In metropolitan areas, about 50% of traffic delays are caused by non-recurring traffic incidents. Hence, accurate prediction of the duration of such events is critical for traffic management authorities. In this paper, we study the predictability of the duration of traffic incidents by considering various external factors. As incident data is typically sparse, training a large number of models (for instance, model for each road) is not possible. On the other hand, training one model for the entire network may not be a suitable solution, as such a model will be too generalized and consequently unsuitable for many relatively rare scenarios. Therefore, we propose to solve this issue by first grouping incidents through common latent similarities among them and then training data-driven predictors for each group. In our numerical analysis we consider incident data from Singapore and the Netherlands. Our results show that by training cluster-specific models we can reduce the prediction error by 19.41% for incidents in Singapore and by 17.8% for incidents in the Netherlands.\",\n \"Title: RA2: Predicting Simulation Execution Time for Cloud-Based Design Space Explorations.\\nYear: 2016\\n\\nAbstract: Design space exploration refers to the evaluation of implementation alternatives for many engineering and design problems. A popular exploration approach is to run a large number of simulations of the actual system with varying sets of configuration parameters to search for the optimal ones. Due to the potentially huge resource requirements, cloud-based simulation execution strategies should be considered in many cases. In this paper, we look at the issue of running large-scale simulation-based design space exploration problems on commercial Infrastructure-as-a-Service clouds, namely Amazon EC2, Microsoft Azure and Google Compute Engine. To efficiently manage cloud resources used for execution, the key problem would be to accurately predict the running time for each simulation instance in advance. This is not trivial due to the currently wide range of cloud resource types which offer varying levels of performance. In addition, the widespread use of virtualization techniques in most cloud providers often introduces unpredictable performance interference.\\n\\nIn this paper, we propose a resource and application-aware (RA2) prediction approach to combat performance variability on clouds. In particular, we employ neural network based techniques coupled with non-intrusive monitoring of resource availability to obtain more accurate predictions. We conducted extensive experiments on commercial cloud platforms using an evacuation planning design problem over a month-long period. The results demonstrate that it is possible to predict simulation execution times in most cases with high accuracy. The experiments also provide some interesting insights on how we should run similar simulation problems on various commercially available clouds.\",\n \"Title: Data driven Adaptive Traffic simulation of an expressway.\\nYear: 2016\\n\\nAbstract: Ubiquitous data from a variety of sources such as smart phones, vehicles equipped with GPS receivers and fixed sensors makes it an exciting time for the implementation of several Advanced Traffic Information and Management Systems (ATMS). Leveraging this data for current traffic state estimation along with short term predictions of traffic flow can have far reaching implications for the next generation of Intelligent Transportation Services (ITS). In this paper, we present our proof-of-concept of such a data driven traffic simulation for the short term prediction and control of traffic flow by simulating a real world expressway through dynamic ramp-metering.\",\n \"Title: Automatic model construction for the behavior of human crowds.\\nYear: 2017\\n\\nAbstract: Graphical abstractDisplay Omitted HighlightsWe propose an automatic methodology to learn generic crowd behavior rules from video data.We formulate the problem of finding behavioral rule from video data as a symbolic regression problem..The behavior rules learned by the proposed method are applicable to different scenarios that have similar behavior patterns.We apply the proposed method to real world datasets and the results have demonstrated the effectiveness of the proposed method. Designing suitable behavioral rules of agents so as to generate realistic behaviors is a fundamental and challenging task in many forms of computational modeling. This paper proposes a novel methodology to automatically generate a descriptive model, in the form of behavioral rules, from video data of human crowds. In the proposed methodology, the problem of modeling crowd behaviors is formulated as a symbolic regression problem and the self-learning gene expression programming is utilized to solve the problem and automatically obtain behavioral rules that match data. To evaluate its effectiveness, we apply the proposed method to generate a model from a video dataset in Switzerland and then test the generality of the model by validating against video data from the United States. The results demonstrate that, based on the observed movement of people in one scenario, the proposed methodology can automatically construct a general model capable of describing the crowd dynamics of another scenario in a different context (e.g., Switzerland vs. U.S.) as long as that the crowd behavior patterns are similar.\",\n \"Title: Competitiveness of Dynamic Bin Packing for Online Cloud Server Allocation.\\nYear: 2017\\n\\nAbstract: Cloud-based systems often face the problem of dispatching a stream of jobs to run on cloud servers in an online manner. Each job has a size that defines the resource demand for running the job. Each job is assigned to run on a cloud server upon its arrival and the job departs after it completes. The departure time of a job, however, is not known at the time of its arrival. Each cloud server has a ...\",\n \"Title: Cloning Agent-Based Simulation.\\nYear: 2017\\n\\nAbstract: Simulation cloning is an efficient way to analyze multiple configurations in a parameter exploration task. A simulation model usually contains a set of tunable parameters for exploring different configurations of a system. To evaluate different design alternatives, multiple simulation instances need to be launched, each evaluating a different parameter configuration. It usually takes a considerable amount of time to execute these simulation instances. Simulation cloning is proposed to reuse computations among simulation instances and to shorten the overall execution time. It is a challenging task to design cloning strategies to explore the computation sharing among simulation instances while maintaining the correctness of execution. In this article, we propose two agent-based simulation (ABS) cloning strategies, the top-down cloning strategy and the bottom-up cloning strategy. The top-down cloning strategy is initially designed and can only be applied to limited scenarios. The bottom-up cloning strategy is an improved strategy to overcome the limitation of the top-down cloning strategy. In the experiments, the effectiveness of the two strategies is analyzed. To show the performance advantages and generality of the bottom-up cloning strategy, a large-scale ABS parameter exploration task is performed, and results are discussed in the article.\",\n \"Title: Relaxing Synchronization in Parallel Agent-Based Road Traffic Simulation.\\nYear: 2017\\n\\nAbstract: Large-scale agent-based traffic simulation is computationally intensive. Parallel computing can help to speed up agent-based traffic simulation. Parallelization of agent-based traffic simulations is generally achieved by decomposing the road network into subregions. The agents in each subregion are executed by a Logical Process (LP). There are data dependencies between LPs which require synchronization of LPs. An asynchronous protocol allows LPs to progress and communicate asynchronously. LPs use lookahead to indicate the time to synchronize with other LPs. Larger lookahead means less frequent synchronization operations. High synchronization overhead is still a major performance issue of large-scale parallel agent-based traffic simulations. In this article, two methods to increase the lookahead of LPs for an asynchronous protocol are developed. They take advantage of uncertainties in traffic simulation to relax synchronization without altering simulation results statistically. Efficiency of the proposed methods is investigated in the parallel agent-based traffic simulator SEMSim Traffic. Experiment results showed that the proposed methods are able to reduce overall running time of the parallel simulation compared to existing methods.\",\n \"Title: A Graph Partitioning Algorithm for Parallel Agent-Based Road Traffic Simulation.\\nYear: 2017\\n\\nAbstract: A common approach of parallelising an agent-based road traffic simulation is to partition the road network into sub-regions and assign computations for each subregion to a logical process (LP). Inter-process communication for synchronisation between the LPs is one of the major factors that affect the performance of parallel agent-based road traffic simulation in a distributed memory environment. Synchronisation overhead, i.e., the number of messages and the communication data volume exchanged between LPs, is heavily dependent on the employed road network partitioning algorithm. In this paper, we propose Neighbour-Restricting Graph-Growing (NRGG), a partitioning algorithm which tries to reduce the required communication between LPs by minimising the number of neighbouring partitions. Based on a road traffic simulation of the city of Singapore, we show that our method not only outperforms graph partitioning methods such as METIS and Buffoon, for the synchronisation protocol used, but also is more resilient than stripe spatial partitioning when partitions are cut more ?nely.\",\n \"Title: Minimizing Cost In Iaas Clouds Via Scheduled Instance Reservation\\nYear: 2017\\n\\nAbstract: Regular diurnal patterns are often seen in the workloads of cloud-based online applications. This kind of non-stationary workloads changes the processing demands over time. To run application services with minimum costs, the number of cloud instances can be dynamically adjusted according to the workload variations. Recently, a new type of scheduled instances has emerged in the Infrastructure-as a-Service market to facilitate such configurations. Scheduled instances can be reserved based on a recurring schedule and they offer price discounts. Meanwhile, cloud vendors require minimum scheduled durations to avoid the overhead of frequently launching and terminating cloud instances. Coupled with traditional on-demand and reserved instances, it becomes more complicated for users to find the optimal combination of these three pricing options to minimize their monetary costs. For the new scheduled instances, not only the number of instances but also their start and stop times have to be decided. In this paper, we develop a fast and effective strategy to solve this problem. Based on the hourly workload distributions, we first compute the optimal number of instances to acquire for each pricing option. Then, we design a scheduling algorithm to arrange the scheduled instances in compliance with the restriction of their scheduled durations. Using the workloads of the LOL online game and the Wikipedia Mobile service as two case studies, the efficacy of our strategy is demonstrated.\",\n \"Title: Fairness-aware Update Schedules for Improving Consistency in Multi-server Distributed Virtual Environments.\\nYear: 2016\\n\\nAbstract: In Distributed Virtual Environments (DVEs), how to guarantee consistency and fairness is a primary concern for improving user experience. As the scale of DVE systems grows fast, multi-server architecture has been widely used in large scale DVEs such as Massively Multiplayer Online Games (MMOGs). In multi-server DVEs (MSDVEs), servers may get saturated with resources such as network bandwidth due to huge resource demand and workload variability. With resource limitations, state updates cannot be disseminated timely and inconsistency and unfairness will be greatly increased if the resources are not allocated properly. In this paper, we propose a fairness-aware state update scheduling algorithm which can minimize total inconsistency while guarantee fairness in MSDVEs under servers' network bandwidth constraints. Experimental results show that the proposed algorithm significantly improves the consistency and fairness compared to other existing update algorithms.\",\n \"Title: On Server Provisioning for Cloud Gaming.\\nYear: 2017\\n\\nAbstract: Cloud gaming has gained significant popularity recently due to many important benefits such as removal of device constraints, instant-on and cross-platform, etc. The properties of intensive resource demands and dynamic workloads make cloud gaming appropriate to be supported by an elastic cloud platform. Facing a large user population, a fundamental problem is how to provide satisfactory cloud gaming service at modest cost. We observe that software maintenance cost could be substantial compared to server running cost in cloud gaming. In this paper, we address the server provisioning problem for cloud gaming to optimize both server running cost and software maintenance cost. We find that the distribution of game softwares among servers triggers a trade-off between the software maintenance cost and server running cost. We formulate the problem with a stochastic model and employ queueing theories to conduct solid theoretical analysis. We then propose several classes of algorithms to approximate the optimal solution. The proposed algorithms are evaluated by extensive experiments using real-world parameters. The results show that the proposed algorithms are computationally efficient, nearly cost-optimal and highly robust to dynamic changes.\",\n \"Title: Parallel Algorithm for Single-Source Earliest-Arrival Problem in Temporal Graphs\\nYear: 2017\\n\\nAbstract: Many real-world networks, including online social networks and communication networks, are commonly modeled as temporal graphs. Answering earliest-arrival queries in temporal graphs is one of the most fundamental studies with numerous applications, such as information diffusion and measuring temporal closeness centrality. As graph sizes are growing rapidly, speedup of query execution time becomes even more important.In this paper, we propose a novel edge-centric parallel algorithm for solving single-source earliest-arrival problem in temporal graphs based on a new data structure named Edge-Scan-Dependency Graph (ESD-Graph). We evaluate the proposed parallel algorithm by theoretical analysis as well as by empirical experiments on real-world temporal graphs and synthetic graphs. Empirical results show that the new parallel algorithm outperforms the existing serial algorithm by up to 8.2 and 9.5 times on multi-core processors for real-world data and synthetic data respectively.\",\n \"Title: Reducing Synchronization Overhead with Computation Replication in Parallel Agent-Based Road Traffic Simulation.\\nYear: 2017\\n\\nAbstract: Road traffic simulation is a useful tool for studying road traffic and evaluating solutions to traffic problems. Large-scale agent-based road traffic simulation is computationally intensive, which triggers the need for conducting parallel simulation. This paper deals with the synchronization problem in parallel agent-based road traffic simulation to reduce the overall simulation execution time. We...\",\n \"Title: Design And Evaluation Of A Data-Driven Scenario Generation Framework For Game-Based Training\\nYear: 2017\\n\\nAbstract: Generating suitable game scenarios that can cater for individual players has become an emerging challenge in procedural content generation. In this paper, we propose a data-driven scenario generation framework for game-based training. An evolutionary scenario generation process is designed with a fitness evaluation methodology that integrates the processes of AI player modeling, simulation and model training based on artificial neural networks. The fitness function for scenario evaluation can be automatically constructed based on the proposed methodology. To further enhance the evaluation of scenarios, we specifically study the impact of the timing of events in a scenario and propose a generic scenario representation model that characterizes individual scenario based on the types and timing of events in the scenario. We present an extensive evaluation of our framework by validating our AI player model, demonstrating the impact of timing of events in a scenario and comparing the effectiveness of our data-driven framework with our previous heuristic-based approach and a random baseline. The results show that it is necessary to consider the timing of events for scenario evaluation and the proposed framework works well in generating scenarios for game-based training.\",\n \"Title: Surrogate assisted calibration framework for crowd model calibration\\nYear: 2017\\n\\nAbstract: Surrogate models are commonly used to approximate the multivariate input or output behavior of complex systems. In this paper, surrogate assisted calibration frameworks are proposed to calibrate the crowd model. To integrate the surrogate models into the evolutionary calibration framework, both the offline and online training based approaches are developed. The offline training needs to generate training set in advance, while the online training can adaptively build and re-build the surrogate model along the evolutionary process. Our simulation results demonstrate that the surrogate assisted calibration framework with the online training is effective and the surrogate model using artificial neural network obtains the best overall performance in the scenario evaluated in the case study.\",\n \"Title: Integration design of supply chain hybrid simulation\\nYear: 2017\\n\\nAbstract: A supply chain (SC) consists of multiple entities representing the retailers, manufacturers, distributors or suppliers. A firm can be one of the entities within the whole SC. To study the external effects on its internal operations, the firm needs to construct a SC model. It may have sufficient data to build a detailed model of its operational processes. However, since it has no control or visibility over the external entities, it is difficult to construct the rest of the SC model at the same level of detail. This paper proposes a hybrid model of the SC using integration design. It allows the whole SC to be captured at the broad view through system dynamics, and the target firm to be represented using agent-based model. The proposed hybrid model is therefore able to capture different behaviors of the same system, e.g, strategic planning of the whole SC, and detailed operational process of individual entities. To demonstrate the applicability of the hybrid model, we evaluate the model through a case study of disruption management policies.\",\n \"Title: CLUST: Simulating Realistic Crowd Behaviour by Mining Pattern from Crowd Videos.\\nYear: 2018\\n\\nAbstract: In this paper, we present a data-driven approach to simulate realistic locomotion of virtual pedestrians. We focus on simulating low-level pedestrians' motion, where a pedestrian's motion is mainly affected by other pedestrians and static obstacles nearby, and the preferred velocities of agents (direction and speed) are obtained from higher level path planning models. Before the simulation, collision avoidance processes (i.e. examples) are extracted from videos to describe how pedestrians avoid collisions, which are then clustered using hierarchical clustering algorithm with a novel distance function to find similar patterns of pedestrians' collision avoidance behaviours. During the simulation, at each time step, the perceived state of each agent is classified into one cluster using a neural network trained before the simulation. A sequence of velocity vectors, representing the agent's future motion, is selected among the examples corresponding to the chosen cluster. The proposed CLUST model is trained and applied to different real-world datasets to evaluate its generality and effectiveness both qualitatively and quantitatively. The simulation results demonstrate that the proposed model can generate realistic crowd behaviours with comparable computational cost.\",\n \"Title: Guide them through: An automatic crowd control framework using multi-objective genetic programming.\\nYear: 2018\\n\\nAbstract: •We propose an automatic framework based on genetic programming to generate crowd control strategies.•We propose a Multi-Objective Cartesian Genetic Programming (MO-CGP) algorithm capable of evolving not only parameters but also rule structures so as to find optimal control strategies for multi-objective optimization.•We demonstrate the effectiveness of the framework in a real life crowd control scenario to guide approximately 400 participants to pass through a multi-story building with shorter travel time and reduced congestion at hotspot segments, comparing to several common baseline crowd models.•We propose a rule analysis method through feature selection machine to identify a limited number of most important features in the evolved rules from GP algorithm effectively.\",\n \"Title: The Server Allocation Problem for Session-Based Multiplayer Cloud Gaming.\\nYear: 2018\\n\\nAbstract: Advances in cloud computing and GPU virtualization are allowing the game industry to move into a cloud gaming era. In this paper, we consider multiplayer cloud gaming (MCG), which is the natural integration of multiplayer online gaming and cloud gaming paradigms. With MCG, a game server and a set of rendering servers for the players need to be located and launched in the clouds for each game sessi...\",\n \"Title: Fast-Forwarding Agent States to Accelerate Microscopic Traffic Simulations.\\nYear: 2018\\n\\nAbstract: Traditionally, the model time in agent-based simulations is advanced in fixed time steps. However, a purely time-stepped execution is inefficient in situations where the states of individual agents are independent of other agents and thus easily predictable far into the simulated future. In this work, we propose a method to accelerate microscopic traffic simulations based on identifying independence among agent state updates. Instead of iteratively updating an agent's state throughout a sequence of time steps, a computationally inexpensive \\\"fast-forward\\\" function advances the agent's state to the time of its earliest possible interaction with other agents. To demonstrate the approach in practice, we present an algorithm to efficiently determine intervals of independence in microscopic traffic simulations and derive a fast-forward function for the popular Intelligent Driver Model (IDM). In contrast to existing acceleration approaches based on reducing the level of model detail, our approach retains the microscopic nature of the simulation. A performance evaluation is performed in a synthetic scenario and on the road network of the city of Singapore. At low traffic densities, we achieved a speedup of up to 2.8, whereas at the highest considered densities, only few opportunities for fast-forwarding could be identified. The algorithm parameters can be tuned to control the overhead of the approach.\",\n \"Title: Optimize the FP-Tree Based Graph Edge Weight Computation on Multi-core MapReduce Clusters\\nYear: 2017\\n\\nAbstract: The FP-tree based edge weight computation (EWC for short) with MapReduce has demonstrated its remarkable performance for extracting weighted graphs from big data for data analysis. However, our investigation finds that existing algorithm includes unnecessary scan on the datasets as well as unnecessary information for the FP-tree construction, which prolong the runtime execution. In addition, applying inappropriate Reducers-to-cores mapping strategy may make it exhaust the resources and fail to complete the job execution. This paper designs, implements and evaluates an optimized FP-tree based graph EWC algorithm with MapReduce on Multi-core Clusters. First, we design a more compact FP-tree based EWC with 2-phase MapReduce, reducing one phase scan of the dataset. Second, we propose a reduced FP-tree data structure to reduce the FP-tree construction cost. Third, we examine two strategies for mapping Reducers to cores for EWC on each multi-core computer: one-Reducer-one-core and one-Reducer-multiple-cores. Finally, an empirical comparison performance study has been carried out on the optimized EWC algorithm against the existing one over a massive application dataset generated by a real social network. The results demonstrate that the optimized FP-tree based EWC algorithm obtains about 39% to 55% percentage improvement in execution time, and in the meantime achieves better scale-out and scale-up speedup. This paper's findings can also be applied to improve the scalability and efficiency of the parallel and distributed execution of applications involving large scale all-pairs set intersection computation over multi-core MapReduce clusters.\",\n \"Title: A Survey on Agent-based Simulation using Hardware Accelerators.\\nYear: 2019\\n\\nAbstract: Due to decelerating gains in single-core CPU performance, computationally expensive simulations are increasingly executed on highly parallel hardware platforms. Agent-based simulations, where simulated entities act with a certain degree of autonomy, frequently provide ample opportunities for parallelisation. Thus, a vast variety of approaches proposed in the literature demonstrated considerable performance gains using hardware platforms such as many-core CPUs and GPUs, merged CPU-GPU chips as well as Field Programmable Gate Arrays. Typically, a combination of techniques is required to achieve high performance for a given simulation model, putting substantial burden on modellers. To the best of our knowledge, no systematic overview of techniques for agent-based simulations on hardware accelerators has been given in the literature. To close this gap, we provide an overview and categorisation of the literature according to the applied techniques. Since, at the current state of research, challenges such as the partitioning of a model for execution on heterogeneous hardware are still addressed in a largely manual process, we sketch directions for future research towards automating the hardware mapping and execution. This survey targets modellers seeking an overview of suitable hardware platforms and execution techniques for a specific simulation model, as well as methodology researchers interested in potential research gaps requiring further exploration.\",\n \"Title: Index Shard Replication Strategies For Improving Resource Utilization In Large Scale Search Engines\\nYear: 2018\\n\\nAbstract: With the rapid growth of the Web scale, large scale search engines have to set up a huge number of machines to place the index files of the Web contents. The index files are normally divided into smaller index shards which are often replicated so that queries can be processed in parallel. We observe that the index shard replication strategy could have a significant impact on the resource utilization of machines. In this paper, we investigate the index shard replication problem with the goal of improving the resource utilization of machines in search engine datacenters. We formulate the problem as a variant of the Multi-Dimensional Vector Bin Packing Problem and propose several strategies to approximate the optimal solution. The proposed strategies are evaluated by extensive experiments using data from real commercial search engines. The results demonstrate the effectiveness of the proposed strategies. Our work also yields many insights about the impact of different input properties on the performance and the key factors that each strategy is sensitive to. We believe that this paper will provide valuable guidance to the choice of the index shard replication strategy in practice.\",\n \"Title: Cost-Efficient Server Provisioning for Cloud Gaming.\\nYear: 2018\\n\\nAbstract: Cloud gaming has gained significant popularity recently due to many important benefits such as removal of device constraints, instant-on, and cross-platform. The properties of intensive resource demands and dynamic workloads make cloud gaming appropriate to be supported by an elastic cloud platform. Facing a large user population, a fundamental problem is how to provide satisfactory cloud gaming service at modest cost. We observe that the software storage cost could be substantial compared to the server running cost in cloud gaming using elastic cloud resources. Therefore, in this article, we address the server provisioning problem for cloud gaming to optimize both the server running cost and the software storage cost. We find that the distribution of game software among servers and the selection of server types both trigger tradeoffs between the software storage cost and the server running cost in cloud gaming. We formulate the problem with a stochastic model and employ queueing theory to conduct a solid theoretical analysis of the system behaviors under different request dispatching policies. We then propose several classes of algorithms to approximate the optimal solution. The proposed algorithms are evaluated by extensive experiments using real-world parameters. The results show that the proposed Ordered and Genetic algorithms are computationally efficient, nearly cost-optimal, and highly robust to dynamic changes.\",\n \"Title: A Role-Dependent Data-Driven Approach for High-Density Crowd Behavior Modeling.\\nYear: 2018\\n\\nAbstract: In this article, we propose a role-dependent (RD) data-driven modeling approach to simulate pedestrians’ motion in high-density scenes. It is commonly observed that pedestrians behave quite differently when walking in a dense crowd. Some people explore routes toward their destinations. Meanwhile, some people deliberately follow others, leading to lane formation. Based on these observations, two roles are included in the proposed model: leader and follower. The motion behaviors of leader and follower are modeled separately. Leaders’ behaviors are learned from real crowd motion data using state-action pairs, while followers’ behaviors are calculated based on specific targets that are obtained dynamically during the simulation. The proposed RD model is trained and applied to different real-world datasets to evaluate its generality and effectiveness. The simulation results demonstrate that the RD model is capable of simulating crowd behaviors in crowded scenes realistically and reproducing collective crowd behaviors such as lane formation.\",\n \"Title: Optimizing Agent-Based Simulations for the GPU\\nYear: 2018\\n\\nAbstract: Agent-based simulation (ABS) is a powerful tool to analyze the behavior of agents interacting with each other. Many simulations contain a large number of agents or re¬quire multiple executions with different parameters, making the simulation-based experimentation slow. In recent years, graphics processing units (GPUs) have proven to be a powerful platform for accelerating ABS. In this paper, we propose several novel techniques to further improve the efficiency of GPU-based ABS. Our techniques reduce the total amount of computation in ABS, improve memory access patterns, and exploit temporal locality to minimize redundant calculations. Furthermore, the optimizations can be implemented as a layer on top of existing simulators, as we demonstrate by modifying the popular GPU-based simulator FLAME. We perform experiments using the Boids and Social Force simulations, and show that our techniques improve overall performance by up to 3.2× and 2.1× respectively compared to the original FLAME.\",\n \"Title: Exploring Execution Schemes for Agent-Based Traffic Simulation on Heterogeneous Hardware.\\nYear: 2018\\n\\nAbstract: Microscopic traffic simulation is associated with substantial runtimes, limiting the feasibility of large-scale evaluation of traffic scenarios. Even though today heterogeneous hardware comprised of CPUs, graphics processing units (GPUs) and fused CPU-GPU devices is inexpensive and widely available, common traffic simulators still rely purely on CPU-based execution, leaving substantial acceleration potentials untapped. A number of existing works have considered the execution of traffic simulations on accelerators, but have relied on simplified models of road networks and driver behaviour tailored to the given hardware platform. Thus, the existing approaches cannot directly benefit from the vast body of research on the validity of common traffic simulation models. In this paper, we explore the performance gains achievable through the use of heterogeneous hardware when relying on typical traffic simulation models used in CPU-based simulators. We propose a partial offloading approach that relies either on a dedicated GPU or a fused CPU-GPU device. Further, we present a traffic simulation running fully on a many-core GPU and discuss the challenges of this approach. Our results show that a CPU-based parallelisation closely approaches the results of partial offloading, while full offloading substantially outperforms the other approaches. We achieve a speedup of up to 28.7x over the sequential execution on a CPU.\",\n \"Title: Incremental calibration of Seat Selection Preferences in Agent-based simulations of Public transport Scenarios.\\nYear: 2018\\n\\nAbstract: The calibration of agent-based pedestrian simulation models requires empirical data. To avoid cost-intensive real-world experiments, human-in-the-loop simulations can be applied in which simulated pedestrians interact with human-controlled agents. However, the experiment results may be unrealistic if the human participants are presented with agents acting according to an uncalibrated model. We propose an incremental calibration approach that aims to address the circular dependency between the behaviour of human and simulated pedestrians. By incrementally adapting the parameters of the simulated agents to match the behaviour of the human participants, we aim to gradually approach a realistic interaction. We evaluate our approach using the simulation of the boarding procedure of a public transport vehicle in 2D and virtual reality experiments. The calibration results are compared with those gathered from a traditional non-incremental calibration. Our results indicate the feasibility of our approach and highlight the necessity for future research on efficient simulation model calibration.\",\n \"Title: Model Preemption based on Dynamic Analysis of simulation Data to Accelerate Traffic light Timing optimisation.\\nYear: 2018\\n\\nAbstract: Since simulation-based optimisation typically requires large numbers of runs to identify sufficiently good solutions, the costs in terms of time and hardware can be enormous. To avoid unnecessary simulation runs, surrogate models can be applied, which estimate the simulation output under a given parameter combination. Model preemption is a related technique that dynamically analyses the simulation state at runtime to identify runs unlikely to result in a high-quality solution and terminates such runs early. However, existing work on model preemption relies on model-specific termination rules. In this paper, we describe an architecture for simulation-based optimisation using model preemption based on estimations of the simulation output. In a case study, the approach is applied to the optimisation of traffic light timings in a traffic simulation. We show that within a given time and hardware budget, model preemption enables the identification of higher-quality solutions than those found through traditional simulation-based optimisation.\",\n \"Title: Dynamic Data Driven Application Systems - Research Challenges and Opportunities.\\nYear: 2018\\n\\nAbstract: Dynamic Data Driven Applications Systems (DDDAS) is a paradigm where data is dynamically integrated into an executing application, and in reverse, the application dynamically steers the measurement process in a feedback control loop. Since its inception in 2000, the DDDAS concept has been successfully applied to a host of application areas. New technologies are emerging such as big data, the Internet of Things, and cloud/edge computing. With these trends DDDAS is poised to have large-scale impacts in areas such as smart cities, manufacturing, health care, and security, to name a few. Each author describes their views concerning the important research challenges facing the DDDAS paradigm and opportunities for impact in the years ahead.\",\n \"Title: Concurrent Hybrid Breadth-First-Search on Distributed PowerGraph for Skewed Graphs\\nYear: 2018\\n\\nAbstract: Large-scale graph-structured computation is becoming increasingly important for various data analytics applications. However, most distributed graph processing frameworks do not directly support efficient implementation of sophisticated algorithms requiring massive graph traversals. In this paper, we propose concurrent hybrid breadth-first-search (BFS) algorithm on a popular distributed graph processing framework (Power-Graph and its optimized version PowerLyra). It leverages the small-world property of skewed graphs which apply to most realworld data sets. Hybrid BFS algorithm changes graph traversal direction to save computational workload and message transmissions. Concurrent BFS algorithm enables running multiple BFS simultaneously while sharing vertex explorations efficiently with bit operations. Extensive experiments are conducted to evaluate performance and scalability on a multi-core computer and a cluster of AWS instances. Concurrent hybrid BFS algorithm dramatically increases graph traversal efficiency with respect to the increasing number of concurrent BFS traversals. Compared with PowerGraph, PowerLyra uses fewer resources, while achieving significantly higher performance and better scalability.\",\n \"Title: Key Message Approach to Optimize Communication of Parallel Applications on Clusters\\nYear: 2003\\n\\nAbstract: Over the past few years, cluster/distributed computing has been gaining popularity. The proliferation of the cluster/distributed computing is due to the improved performance and increased reliability of these systems. Many parallel programming languages and related parallel programming models have become widely accepted. However, one of the major shortcomings of running parallel applications on cluster/distributed computing environments is the high communication overhead incurred. To reduce the communication overhead, and thus the completion time of a parallel application, this paper describes a simple, efficient and portable Key Message (KM) approach to support parallel computing on cluster/distributed computing environments. To demonstrate the advantage of the KM approach, a prototype runtime system has been implemented and evaluated. Our preliminary experimental results show that the KM approach has better improvement on communication of a parallel application when network background load increases or the computation to communication ratio of the application decreases.\",\n \"Title: Managing irregular workloads of cooperatively shared computing clusters\\nYear: 2004\\n\\nAbstract: Cooperative resource sharing enables distinct organizations to form a federation of computing resources. A functional broker is deployed to facilitate remote resource access within the community grid. A major issue is the problem of correlations in job arrivals caused by seasonal usage and/or coincident resource usage demand patterns where high levels of burstiness in job arrivals can cause the job queue of the broker to grow to an extent such that its performance becomes severely impaired. Since job arrivals cannot be controlled, management strategies must be employed to admit jobs to sustain the resource allocation performance of the broker. In this paper, we present a theoretical analysis of the problem of job traffic burstiness on resource allocation performance in order to elicit the general job management strategies to be employed. Based on the analysis, we define and justify a job management framework for the resource broker to cope with overload conditions caused by job arrival correlations.\",\n \"Title: Efficient Parallel Simulation over Social Contact Network with Skewed Degree Distribution.\\nYear: 2017\\n\\nAbstract: Social contact network (SCN) models the contacts between people by their daily activities. It can be formalized by an agent-to-location bipartite graph. The simulations over SCN are employed to study the complex social dynamics such as information propagation and disease spread among large-scale population. A challenge to the simulation is the skewed degree distribution of SCN, which contains a few hub locations with large numbers of visitors. The skewed degree distribution can cause load imbalance for parallel simulation and greatly degrade the execution performance. This paper proposes an approach which decomposes hub locations into small splits. Thus, SCN can be partitioned with better balanced workloads and multiple splits are able to run in parallel. Based on the pattern of information transmission between agents, we duplicate necessary data among splits to ensure the correctness of simulation. Furthermore, we enhance the parallel algorithm of SCN simulation to reduce the additional overhead from communication between splits. Finally, we build an experiment with epidemic simulation on an open dataset. The experimental results demonstrate that our approach achieves 14~35% performance improvement compared with the partitioning method without decomposition of hub locations.\",\n \"Title: Evaluation of Conflict Resolution Methods for Agent-Based Simulations on the GPU.\\nYear: 2018\\n\\nAbstract: Graphics processing units (GPUs) have been shown to be well-suited to accelerate agent-based simulations. A fundamental challenge in agent-based simulations is the resolution of conflicts arising when agents compete for simulated resources, which may introduce substantial overhead. A variety of conflict resolution methods on the GPU have been proposed in the literature. In this paper, we systematize and compare these methods and propose two simple new variants. We present performance measurements on the example of the well-known segregation model. We show that the choice of conflict resolution method can substantially affect the simulation performance. Further, although methods in which agents actively indicate their interest in a resource require the use of costly atomic operations, these methods generally outperform the alternatives.\",\n \"Title: A Graph-Based Model To Measure Structural Redundancy For Supply Chain Resilience\\nYear: 2019\\n\\nAbstract: Globalisation and lean initiatives increase the vulnerabilities of the supply chains (SC), where disruptions in any plant in a supply chain network (SCN) can propagate throughout the whole SCN. Redundancy is part of the SC re-engineering to improve supply chain resilience (SCRES). This paper presents a conceptual model of an SCN using graph theory, considering the relationships between plants and materials. Based on the model, the structural redundancy of the SCN is measured, which is used to assess SCRES. This assessment approach focuses on the resilience of the SCN against disruptions. Case studies are discussed to illustrate the applicability of this model and show that increasing structural redundancy of the SCN improves SCRES against disruptions.\",\n \"Title: Efficient Parallel Simulation over Large-scale Social Contact Networks\\nYear: 2019\\n\\nAbstract: Social contact network (SCN) models the daily contacts between people in real life. It consists of agents and locations. When agents visit a location at the same time, the social interactions can be established among them. Simulations over SCN have been employed to study social dynamics such as disease spread among population. Because of the scale of SCN and the execution time requirement, the simulations are usually run in parallel. However, a challenge to the parallel simulation is that the structure of SCN is naturally skewed with a few hub locations that have far more visitors than others. These hub locations can cause load imbalance and heavy communication between partitions, which therefore impact the simulation performance. This article proposes a comprehensive solution to address this challenge. First, the hub locations are decomposed into small locations, so that SCN can be divided into partitions with better balanced workloads. Second, the agents are decomposed to exploit data locality, so that the overall communication across partitions can be greatly reduced. Third, two enhanced execution mechanisms are designed for locations and agents, respectively, to improve simulation parallelism. To evaluate the efficiency of the proposed solution, an epidemic simulation was developed and extensive experiments were conducted on two computer clusters using three SCN datasets with different scales. The results demonstrate that our approach can significantly improve the execution performance of the simulation.\",\n \"Title: A Data-driven Path Planning Model for Crowd Capacity Analysis\\nYear: 2019\\n\\nAbstract: •Developed a data-driven pedestrian origin-destination and route choice model by learning from video data.•The data-driven model can be used for capacity analysis of the building layout.•Enhanced the route choice model by taking into account the crowd density in the building layout on route choice.•Developed the crowd density aware route choice model through virtual reality experiments and Support Vector Classification.\",\n \"Title: From Effects to Causes: Reversible Simulation and Reverse Exploration of Microscopic Traffic Models.\\nYear: 2019\\n\\nAbstract: We propose an approach for reverse-in-time exploration of the state space of microscopic traffic simulations starting from a user-specified class of outcomes. As a basis for our approach, we present a reversible execution scheme applicable to common car-following and lane-changing models from the traffic simulation literature. The execution scheme permits perfect reversal of a previous forward simulation, which to our knowledge has not been attempted previously in the context of established traffic simulation models. Further, we perform reverse state space explorations directly from user-specified simulation states, i.e., reverse-in-time model checking. By exploring all sequences of possible previous states from a final state, reachability questions can be answered more conclusively than purely through forward simulations. In a case study, reverse exploration is used to identify conditions that lead to specified accident situations, with running time reductions by factors of more than 20 compared to traditional forward exploration.\",\n \"Title: Transitioning Spiking Neural Network Simulators to Heterogeneous Hardware.\\nYear: 2019\\n\\nAbstract: Spiking neural networks (SNN) are among the most computationally intensive types of simulation models, with node counts on the order of up to 10^11. Currently, there is intensive research into hardware platforms suitable to support large-scale SNN simulations, whereas several of the most widely used simulators still rely purely on the execution on CPUs. Enabling the execution of these established simulators on heterogeneous hardware allows new studies to exploit the many-core hardware prevalent in modern supercomputing environments, while still being able to reproduce and compare with results from a vast body of existing literature. In this paper, we propose a transition approach for CPU-based SNN simulators to enable the execution on heterogeneous hardware (e.g., CPUs, GPUs, and FPGAs) with only limited modifications to an existing simulator code base, and without changes to model code. Our approach relies on manual porting of a small number of core simulator functionalities as found in common SNN simulators, whereas unmodified model code is analyzed and transformed automatically. We apply our approach to the well-known simulator NEST and make a version executable on heterogeneous hardware available to the community. Our measurements show that at full utilization, a single GPU achieves the performance of about 9 CPU cores.\",\n \"Title: GAugur: Quantifying Performance Interference of Colocated Games for Improving Resource Utilization in Cloud Gaming\\nYear: 2019\\n\\nAbstract: Cloud gaming has been very popular recently, but providing satisfactory gaming experiences to players at a modest cost is still challenging. Colocating several games onto one server could improve server utilization. To enable efficient colocations while providing Quality of Service (QoS) guarantees, a precise quantification of performance interference among colocated games is required. However, achieving such precise interference prediction is very challenging for games due to the complexity introduced by the contention on many shared resources across CPU and GPU. Moreover, the distinctive properties of cloud gaming require that the prediction model should be constructed beforehand and the prediction should be made instantaneously at request arrivals, which further increases the difficulty. The existing solutions are either not applicable or not effective due to many limitations. In this paper, we present GAugur, a novel methodology that enables highly accurate prediction of the performance interference among games arbitrarily colocated. By leveraging machine learning technologies, GAugur is able to capture the complex relationship between the interference and the contention features of colocated games. We evaluate GAugur through extensive experiments using a large number of real popular games. The results show that GAugur is able to identify whether a colocated game satisfies QoS requirement within an average error of 5%, and is able to quantify the performance degradation of a colocated game within an average error of 7.9%, which significantly outperforms the alternatives. Moreover, GAugur incurs an offline profiling cost linear to the number of games, and negligible overhead for online prediction. We apply GAugur to guiding efficient game colocations for cloud gaming. Experimental results show that GAugur is able to increase the resource utilization by 20% to 60%, and improve the overall performance by up to 15%, compared to the state-of-the-art solutions.\",\n \"Title: An Agent-Based Model For Evaluating The Boarding And Alighting Efficiency Of Autonomous Public Transport Vehicles\\nYear: 2019\\n\\nAbstract: A key metric in the design of interior layouts of public transport vehicles is the dwell time required to allow passengers to board and alight. Real-world experimentation using physical vehicle mock-ups and involving human participants can be performed to compare dwell times among vehicle designs. However, the associated costs limit such experiments to small numbers of trials. In this paper, we propose an agent-based simulation model of the behavior of passengers during boarding and alighting. High-level strategical behavior is modeled according to the Recognition-Primed Decision paradigm, while the low-level collision-avoidance behavior relies on an extended Social Force Model tailored to our scenario. To enable successful navigation within the confined space of the vehicle, we propose a mechanism to emulate passenger turning while avoiding complex geometric computations. We validate our model against real-world experiments from the literature, demonstrating deviations of less than 11%. In a case study, we evaluate the boarding and alighting times required by three autonomous vehicle interior layouts proposed by industrial designers.\",\n \"Title: A New Double Rank-based Multi-workflow Scheduling with Multi-objective Optimization in Cloud Environments\\nYear: 2021\\n\\nAbstract: Workflow scheduling in clouds has been extensively researched. Many workflows from different users could be submitted to clouds at the same time and cloud providers should handle them simultaneously. So, it is necessary to consider the problem of scheduling multi-workflow. In addition, cloud computing systems can offer some special features, like Pay-Per-Use and Quality of Service (QoS) over the I...\",\n \"Title: Data-driven Microscopic Traffic Modelling and Simulation using Dynamic LSTM\\nYear: 2021\\n\\nAbstract: ABSTRACTWith the increasing popularity of Digital Twin, there is an opportunity to employ deep learning models in symbiotic simulation system. Symbiotic simulation can replicate multiple what-if simulation instances from its real-time reference simulation (base simulation) for short-term forecasting. Hence, it is a useful tool for just-in-time decision making process. Recent trends on symbiotic simulation studies emphasize on its combination with machine learning. Despite its success and usefulness, very few works focus on application of such a hybrid system in microscopic traffic simulation. Existing application of machine (deep) learning models in microscopic traffic simulation is confined to either predictive analysis or offline simulation-based prescriptive analysis. Thus, there is also lack of work on updating parameters of a deep learning model dynamically for real-time traffic simulation. This is necessary if the learning-based model is to be used as part of the base simulation so that \\\"Just-in-time (JIT)\\\" what-if simulation initialized from the model can make better short-term forecasts. This paper proposes a data-driven modelling and simulation framework to dynamically update parameters of Long Short-term Memory (LSTM) for JIT microscopic traffic simulation. Extensive experiments were carried out to demonstrate its effectiveness in terms of more accurate short-term forecasting than other baseline models.\",\n \"Title: Causality and Consistency of State Update Schemes in Synchronous Agent-based Simulations\\nYear: 2021\\n\\nAbstract: ABSTRACTIn an agent-based simulation (ABS), a state update scheme carries out the transitions of agents from one state to the next. To produce correct simulation results, the update scheme must respect the cause-and-effect relationships defined by the agent-based model and ensure that the resulting overall simulation state is internally consistent. At the same time, the update scheme should be efficient enough to meet a simulationist's demand for timely results. Considering the common class of synchronous time-driven ABS, a number of update schemes have been employed in the literature and simulation frameworks. In this paper, various implementations of update schemes are analyzed and contrasted with respect to their ability to maintain the simulation correctness as well as their performance characteristics. A semantic model is formulated to define the reference behavior of synchronous time-driven ABS updates and model the dependencies among agent updates using a state access graph. Relying on the formalization, conditions under which different update schemes achieve causality are shown. Further, resolution methods are categorized according to their coordination mechanisms to achieve consistency by resolving conflicts among agent state updates. Through two case studies, the empirical performance of different update schemes and resolution methods are evaluated. For sequential execution, an update scheme based on the agent's dependencies achieves the highest performance, whereas in the parallel case, the choice of update scheme involves a tradeoff between execution time and memory usage. If deterministic simulation output is required, decentralized coordination generally outperforms centralized coordination. The results can assist implementers and researchers in their selection of appropriate methods in the design and implementation of agent-based simulators.\",\n \"Title: A Parallel Hierarchical Sort-based Interest Matching Algorithm\\nYear: 2021\\n\\nAbstract: ABSTRACTInterest management is a filtering technique to reduce communication in simulation. It involves a process called \\\"interest matching\\\" to identify intersections between two sets of d-dimensional axis-parallel rectangles. Because of frequent demands in simulation execution, interest matching becomes a bottleneck as the problem size grows. However, classical interest matching algorithms, mainly designed for serial processing, do not take advantage of modern multicore processors' computing power. Recent parallel interest matching algorithms can fill the gap, but there is scope for improvement. In this paper, we propose a parallel hierarchical sort-based interest matching algorithm. It embeds subscription regions into an interest management tree and allows update regions compare with nodes of the tree to find results in parallel. The association between adjacent nodes and the hierarchical relation between parent-child nodes can serve to eliminate unnecessary operations. Moreover, we also provide proof to confirm the correctness and a detailed analysis of time-complexity. The experimental results demonstrate that the proposed algorithm can achieve better performance than state-of-art algorithms.\",\n \"Title: Hot Area Targeting Dead Reckoning for Distributed Virtual Environments\\nYear: 2021\\n\\nAbstract: ABSTRACTDead reckoning (DR) is a key technique to increase scalability in Distributed Virtual Environments (DVE). Replacing data transmission with prediction, DR relies on its prediction capability to reduce the bandwidth consumption in the cost of inconsistency among participants. We propose a hot area targeting DR (HATDR) approach to increase the prediction capability by the hot area targeting pattern discovered with a noise-resistant clustering approach. This approach is shown to be robust against hyperparameters. Experiments carried out with a real-life MMOG dataset show that HATDR is comparable to the state-of-the-art DR approaches.\",\n \"Title: Data-driven Crowd Modeling Techniques: A Survey\\nYear: 2022\\n\\nAbstract: AbstractData-driven crowd modeling has now become a popular and effective approach for generating realistic crowd simulation and has been applied to a range of applications, such as anomaly detection and game design. In the past decades, a number of data-driven crowd modeling techniques have been proposed, providing many options for people to generate virtual crowd simulation. This article provides a comprehensive survey of these state-of-the-art data-driven modeling techniques. We first describe the commonly used datasets for crowd modeling. Then, we categorize and discuss the state-of-the-art data-driven crowd modeling methods. After that, data-driven crowd model validation techniques are discussed. Finally, six promising future research topics of data-driven crowd modeling are discussed.\",\n \"Title: E 2 T-CVL: An Efficient and Error-Tolerant Approach for Collaborative Vehicle Localization\\nYear: 2022\\n\\nAbstract: The proliferation of vehicle-to-vehicle (V2V) communication techniques has resulted in collaborative vehicle localization (CVL) approaches that localize a target vehicle by leveraging the state information of nearby vehicles. However, CVL approaches typically require a large search space to locate the real position of a target vehicle and assume small measurement errors of nearby vehicle informati...\",\n \"Title: Research on the collaboration of service selection and resource scheduling for IoT simulation workflows\\nYear: 2022\\n\\nAbstract: Cloud resources provide a promising way to efficiently perform the needed simulation tasks for a complex manufacturing process. Most of the existing work focuses only on how to effectively schedule computing resources to execute computing requirements of simulation workflows in Internet of Things (IoT) applications. Research on the scheduling of simulation workflows in consideration of task ordering, service selection, and resource allocation altogether has not been lacking. To fill in this void, this paper proposes a cloud-based 3-stage workflow scheduling model. Before scheduling computing resources to complete task requirements, the order of the tasks is determined and the services that can meet the task requirements are selected. In this model, the workload to satisfy task requirements is not fixed and takes on a different value depending upon the service selected with its unique complexity and accuracy. An optimization function that transforms and integrates makespan, cost, and accuracy in a unique way is proposed. For its solution, the relatively new symbiotic organisms search (SOS) algorithm is modified and two SOS-based optimization strategies are developed, i.e., joint optimization-based SOS (JOSOS) and split optimization-based SOS (SOSOS). The simulation results reveal that SOS-based algorithms, especially the SOSOS method, outperform all compared algorithms. Based on the proposed method, simulation services and computing resources can be rationally selected and scheduled to ensure the requirements of IoT applications.\",\n \"Title: A wholistic optimization of containerized workflow scheduling and deployment in the cloud–edge environment\\nYear: 2022\\n\\nAbstract: Digital Twin in Industry 4.0 utilizes Internet of Things (IoT) to collect real-life data and combine it with simulation models for product design and development. The simulation process can be executed as a workflow, consisting of tasks with precedence constraints. In a container-based workflow execution system, each task in the workflow is executed in a container within a virtual machine (VM). In this paper, a three-step scheduling model is proposed to combine scheduling of container-based workflows and the deployment of containers on a cloud–edge environment. In the first step, virtual CPU (vCPU) is allocated for each container to enable vCPU sharing among different containers. Next, two-step resource deployment is used to schedule the containers onto VM, and VM onto the physical machines in either edge or cloud environment. Multiple objectives are considered, including minimizing makespan, load imbalance, and energy consumption, from the perspective of cloud–edge resources as well as containerized workflows. To obtain a set of non-dominated solutions, three evolution strategies are designed and combined with two multi-objective algorithm frameworks — co-evolution strategy (CES), basic non-co-evolution strategy (B-NCS), and hybrid non-co-evolution strategy (H-NCS). Simulation results demonstrate that the proposed model outperforms the existing two-step scheduling model and H-NCS performs better than other strategies.\",\n \"Title: Distribution-Based Weights Estimation for Map Matching Algorithms\\nYear: 2022\\n\\nAbstract: With the development of mobile computing, map matching algorithms are utilized to recover vehicles’ traveling routes. Existing map matching algorithms usually infer the traveling routes based on a driving cost model that considers various traveling features and driving preferences (referred to as weights). In general, the weights are estimated either empirically or through data-driven approaches. For empirical setting, the weights are determined based on field studies and must be reestimated when the driving scenarios are changed. Alternatively, in data-driven approaches, the weights are determined from the analysis of historical routes of vehicles. However, estimation bias may be introduced due to the selection of data sources. To decrease the estimation bias, this article proposes a distribution-based weights estimation method. Specifically, the weights are estimated by inferring their distributions through Bayesian inference based on the driver traces collected in a city scale. Next, a sampling-based strategy is adopted to determine the weights values from their distributions. Experimental results show that the proposed approach achieves a higher map matching accuracy than the existing approaches, and it is applicable for both linear and nonlinear driving cost models used in map matching algorithms. Moreover, the estimated weights can help to understand driver preferences in different traveling cases.\",\n \"Title: SPIDER: An Effective, Efficient and Robust Load Scheduler for Real-time Split Frame Rendering\\nYear: 2022\\n\\nAbstract: Interactive graphics applications are generally latency-critical, while using multiple GPUs to accelerate such applications becomes possible recently with support from both hardware and software. Split frame rendering (SFR) is a popular approach for multi-GPU rendering, which splits a frame into disjoint regions and assigns the regions to different GPUs. Load scheduling of SFR is a crucial but challenging issue for achieving maximum rendering performance in real-time rendering, which is not well addressed by the existing solutions. In this paper, we propose SPIDER, a load scheduler which leverages fuzzy PID (proportional integral derivative) controller to schedule the rendering workload among GPUs. SPIDER has several distinguished properties: it is a feedback based mechanism which does not need a full knowledge of the dynamic system; it is very computationally efficient and easy to implement; it is highly robust to dynamic workload changes. Extensive experiments are conducted to evaluate SPIDER and the results show that SPIDER always achieves near-optimal performance for various workload patterns, which outperforms the state-of-the-art baselines signif-icantly.\",\n \"Title: Improving Scalability, Sustainability and Availability via Workload Distribution in Edge-Cloud Gaming\\nYear: 2022\\n\\nAbstract: ABSTRACTRecent uses of heterogeneous mobile and lightweight devices encourage computations to be abstracted remotely as black box systems. This same concept applies for cloud gaming in which computer games are located and run inside remote rendering servers (RSes). While cloud gaming enables lightweight devices with sufficient input capabilities and network connection to be able to play desktop games, latency and cost issue become significant hindrances in recent applications. In this paper, we came up with our edge-cloud gaming architecture which reduces the overall workload in RSes while increasing playerbase coverage by using edge RSes. Furthermore, we also proposed our allocation algorithm in order to assign incoming players to RSes. From our experiments, our proposed architecture has higher playerbase coverage while our allocation algorithm significantly reduces the cost in both single and batch player arrival pattern.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":200,"string":"200"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":279,"string":"279"}}},{"rowIdx":280,"cells":{"question_id":{"kind":"string","value":"Liqiang Wang"},"question":{"kind":"string","value":"Generate an abstract for the title \"Asynchronous Delay-Aware Accelerated Proximal Coordinate Descent for Nonconvex Nonsmooth Problems.\" using the following items: Nonconvex, nonsmooth, optimization, accelerated algorithm, practical efficiency."},"answer":{"kind":"string","value":"Nonconvex and nonsmooth problems have recently attracted considerable attention in machine learning. However, developing efficient methods for the nonconvex and nonsmooth optimization problems with certain performance guarantee remains a challenge. Proximal coordinate descent (PCD) has been widely used for solving optimization problems, but the knowledge of PCD methods in the nonconvex setting is very limited. On the other hand, the asynchronous proximal coordinate descent (APCD) recently have received much attention in order to solve large-scale problems. However, the accelerated variants of APCD algorithms are rarely studied. In this paper, we extend APCD method to the accelerated algorithm (AAPCD) for nonsmooth and nonconvex problems that satisfies the sufficient descent property, by comparing between the function values at proximal update and a linear extrapolated point using a delay-aware momentum value. To the best of our knowledge, we are the first to provide stochastic and deterministic accelerated extension of APCD algorithms for general nonconvex and nonsmooth problems ensuring that for both bounded delays and unbounded delays every limit point is a critical point. By leveraging Kurdyka-Lojasiewicz property, we will show linear and sublinear convergence rates for the deterministic AAPCD with bounded delays. Numerical results demonstrate the practical efficiency of our algorithm in speed."},"correct_answer":{"kind":"string","value":"Nonconvex and nonsmooth problems have recently attracted considerable attention in machine learning. However, developing efficient methods for the nonconvex and nonsmooth optimization problems with certain performance guarantee remains a challenge. Proximal coordinate descent (PCD) has been widely used for solving optimization problems, but the knowledge of PCD methods in the nonconvex setting is very limited. On the other hand, the asynchronous proximal coordinate descent (APCD) recently have received much attention in order to solve large-scale problems. However, the accelerated variants of APCD algorithms are rarely studied. In this paper, we extend APCD method to the accelerated algorithm (AAPCD) for nonsmooth and nonconvex problems that satisfies the sufficient descent property, by comparing between the function values at proximal update and a linear extrapolated point using a delay-aware momentum value. To the best of our knowledge, we are the first to provide stochastic and deterministic accelerated extension of APCD algorithms for general nonconvex and nonsmooth problems ensuring that for both bounded delays and unbounded delays every limit point is a critical point. By leveraging Kurdyka-Lojasiewicz property, we will show linear and sublinear convergence rates for the deterministic AAPCD with bounded delays. Numerical results demonstrate the practical efficiency of our algorithm in speed."},"documents":{"kind":"list like","value":["Title: Fully Secure Attribute-Based Encryption with Non-monotonic Access Structures\nYear: 2013\n\nAbstract: Along with the development of the Internet, the traditional public key encryption system becomes insufficient for many newly emerging applications, such as the cloud services. Then the ABE is proposed to meet the urgent demands. The study on attribute-based encryption mainly concern on two issues: how to improve its expressibility and achieve stronger security. This paper has proposed a attribute-based encryption scheme that has good property in both two points: our scheme allows a user's private key to be expressed in non-monotonic access structures, and we prove its fully security in the standard model. Furthermore, the performance of our scheme is as efficient as the less expressive and selective security ones.","Title: Running smart process based on goals\nYear: 2008\n\nAbstract: When Web services are used to coalesce around the distributed applications, one prominent solution to manage and coordinate Web services is the use of process management. Many researches have been done to deal with automatic discovery and composition issues of Web services. However, the problem of how to run a process that is composed of distributed services is seldom considered. In this paper, based on our previous work, the smart process-based application model (SPM), we formalize smart process (SP) using algebra CCS, and discuss the benefits. In particular, we propose goal-based algorithms to run Smart Process.","Title: An optimized parallel LSQR algorithm for seismic tomography.\nYear: 2013\n\nAbstract: The LSQR algorithm developed by Paige and Saunders (1982) is considered one of the most efficient and stable methods for solving large, sparse, and ill-posed linear (or linearized) systems. In seismic tomography, the LSQR method has been widely used in solving linearized inversion problems. As the amount of seismic observations increase and tomographic techniques advance, the size of inversion problems can grow accordingly. Currently, a few parallel LSQR solvers are presented or available for solving large problems on supercomputers, but the scalabilities are generally weak because of the significant communication cost among processors. In this paper, we present the details of our optimizations on the LSQR code for, but not limited to, seismic tomographic inversions. The optimizations we have implemented to our LSQR code include: reordering the damping matrix to reduce its band-width for simplifying the communication pattern and reducing the amount of communication during calculations; adopting sparse matrix storage formats for efficiently storing and partitioning matrices; using the MPI I/O functions to parallelize the date reading and result writing processes; providing different data partition strategies for efficiently using computational resources. A large seismic tomographic inversion problem, the full-3D waveform tomography for Southern California, is used to explain the details of our optimizations and examine the performance on Yellowstone supercomputer at the NCAR-Wyoming Supercomputing Center (NWSC). The results showed that the required wall time of our code for the same inversion problem is much less than that of the LSQR solver from the PETSc library (Balay et al., 1997).","Title: HAVE: Detecting Atomicity Violations via Integrated Dynamic and Static Analysis\nYear: 2009\n\nAbstract: The reality of multi-core hardware has made concurrent programs pervasive. Unfortunately, writing correct concurrent programs is difficult. Atomicity violation, which is caused by concurrently executing code unexpectedly violating the atomicity of a code segment, is one of the most common concurrency errors. However, atomicity violations are hard to find using traditional testing and debugging techniques. This paper presents a hybrid approach that integrates static and dynamic analyses to attack this problem. We first perform static analysis to obtain summaries of synchronizations and accesses to shared variables. The static summaries are then instantiated with runtime values during dynamic executions to speculatively approximate the behaviors of branches that are not taken. Compared to dynamic analysis, the hybrid approach is able to detect atomicity violations in unexecuted parts of the code. Compared to static analysis, the hybrid approach produces fewer false alarms. We implemented this hybrid analysis in a tool called HAVE that detects atomicity violations in multi-threaded Java programs. Experiments on several benchmarks and real-world applications demonstrate promising results.","Title: A model-driven partitioning and auto-tuning integrated framework for sparse matrix-vector multiplication on GPUs\nYear: 2011\n\nAbstract: Sparse Matrix-Vector Multiplication (SpMV) is very common to scientific computing. The Graphics Processing Unit (GPU) has recently emerged as a high-performance computing platform due to its massive processing capability. This paper presents an innovative performance-model driven approach for partitioning sparse matrix into appropriate formats, and auto-tuning configurations of CUDA kernels to improve the performance of SpMV on GPUs. This paper makes the following contributions: (1) Propose an empirical CUDA performance model to predict the execution time of SpMV CUDA kernels. (2) Design and implement a model-driven partitioning framework to predict how to partition the target sparse matrix into one or more partitions and transform each partition into appropriate storage format, which is based on the fact that the different storage formats of sparse matrix can significantly affect the performance of SpMV. (3) Integrate the model-driven partitioning with our previous auto-tuning framework to automatically adjust CUDA-specific parameters to optimize performance on specific GPUs. Compared to the NVIDIA's existing implementations, our approach shows a substantial performance improvement. It has 222%, 197%, and 33% performance improvement on the average for CSR vector kernel, ELL kernel and HYB kernel, respectively.","Title: Miniaturized CMOS Imaging Module with Real-time DSP Technology for Endoscope and Laryngoscope Applications\nYear: 2009\n\nAbstract: Miniaturized video camera is a key component in modern medical devices such as endoscopes or other minimally invasive instruments. Here we present a new imaging module which is so small that it can fit through the instrument channels of conventional endoscopes and laryngoscopes. This imaging module includes a 1/18-in. CMOS image sensor and a small integrated lens with field of view of 120°. A Blackfin DSP is used for real-time video processing, including lens distortion compensation, white balance, auto exposure and edge enhancement. The output video signals are displayed on a color LCD monitor. Two white LEDs provide lighting condition. The tip of the imaging module is packaged in a cylinder of diameter 2.5 mm, making many medical applications such as intubation and endoscopy less invasive. It can also be used in machine vision, security and surveillance where small size is important.","Title: An Integrated Framework for Checking Concurrency-Related Programming Errors\nYear: 2009\n\nAbstract: Countless challenges to preserving a user’s location privacy exist and have become more important than ever before with the proliferation of handheld devices and the pervasive use of Location-based Services. It is not possible to access Location-based ...","Title: Rapid 3D Seismic Source Inversion Using Windows Azure and Amazon EC2\nYear: 2011\n\nAbstract: With its rapid development, cloud computing has been increasingly adopted by scientists for large-scale scientific computation. Compared to the traditional computing platforms such as cluster and supercomputer, cloud computing is more elastic in the support of real-time computation and more powerful in the management of large-scale datasets. This paper presents our experience on designing and implementing seismic source inversion on both cluster (specifically, MPI-based) and cloud computing (specifically, Amazon EC2 and Microsoft Windows Azure). Our experiment shows that applying cloud computing to seismic source inversion is feasible and has its advantages. In addition, we notice that both cluster and Amazon EC2 have obviously better performance than Windows Azure. Cloud computing is suited for real-time processing scientific applications but it (especially Azure) does not work well for tightly-coupled applications.","Title: Rapid Processing of Synthetic Seismograms Using Windows Azure Cloud\nYear: 2010\n\nAbstract: Currently, numerically simulated synthetic seismograms are widely used by seismologists for seismological inferences. The generation of these synthetic seismograms requires large amount of computing resources, and the maintenance of these observed seismograms requires massive storage. Traditional high-performance computing platforms is inefficient to handle these applications because rapid computations are needed and large-scale datasets should be maintained. The emerging cloud computing platform provides an efficient substitute. In this paper, we introduce our experience on implementing a computational platform for rapidly computing and delivering synthetic seismograms on Windows Azure. Our experiment shows that cloud computing is an ideal platform for such kind of applications.","Title: CRI: symbolic debugger for MCAPI applications\nYear: 2010\n\nAbstract: We present a trace-driven SMT-based symbolic debugging tool for MCAPI (Multicore Association Communication API) applications. MCAPI is a newly proposed standard that provides an API for connectionless and connection-oriented communication in multicore applications. Our tool obtains a trace by executing an instrumented MCAPI. The collected trace is then encoded into an SMT formula such that its satisfiability indicates the existence of a reachable error state such as an assertion failure.","Title: Detecting potential deadlocks with static analysis and run-time monitoring\nYear: 2005\n\nAbstract: Concurrent programs are notorious for containing errors that are difficult to reproduce and diagnose. A common kind of concurrency error is deadlock, which occurs when a set of threads is blocked each trying to acquire a lock held by another thread in that set. Static and dynamic (run-time) analysis techniques exist to detect deadlocks. Havelund's GoodLock algorithm detects potential deadlocks at run-time. However, it detects only potential deadlocks involving exactly two threads. This paper presents a generalized version of the GoodLock algorithm that detects potential deadlocks involving any number of threads. Run-time checking may miss errors in unexecuted code. On the positive side, run-time checking generally produces fewer false alarms than static analysis. This paper explores the use of static analysis to automatically reduce the overhead of run-time checking. We extend our type system, Extended Parameterized Atomic Java (EPAJ), which ensures absence of races and atomicity violations, with Boyapati et al.'s deadlock types. We give an algorithm that infers deadlock types for a given program and an algorithm that determines, based on the result of type inference, which run-time checks can safely be omitted. The new type system, called Deadlock-Free EPAJ (DEPAJ), has the added benefit of giving stronger atomicity guarantees than previous atomicity type systems.","Title: Hybrid fire detection using hidden Markov model and luminance map\nYear: 2011\n\nAbstract: Recently, fire detection is a hot research topic. Although many detection methods have been proposed, there exist high false alarms because of the interference of fire-colored moving object in the complex environments. In this paper, a hybrid method is proposed. First, we get the set of candidate fire regions. Then these candidate fire regions are analyzed to exclude the fire-colored moving object. Our contributions are using the hidden Markov model (HMM) based on spatio-temporal feature and the variance of luminance map motivated by visual attention, and combining both for fire detection. The wrong detection can be reduced greatly. Experiment results show our proposed method has a good performance and it is robust to be used in complex environment compared with previous algorithms.","Title: Automated type-based analysis of data races and atomicity\nYear: 2005\n\nAbstract: Concurrent programs are notorious for containing errors that are difficult to reproduce and diagnose at run-time. This motivated the development of type systems that statically ensure the absence of some common kinds of concurrent programming errors including data races and atomicity violations. A method is atomic if every execution of the concurrent program is equivalent to an execution in which the atomic method is executed without being interleaved with other concurrently executed methods. Atomicity is a common correctness requirement in concurrent programs; atomicity violations may indicate incorrect synchronization. This paper presents Extended Parameterized Atomic Java (EPAJ), a type system for specifying and verifying atomicity in Java programs. EPAJ combines Flanagan and Qadeer's atomicity types [11] with a new and significantly more expressive type system for analyzing data races, called Extended Parameterized Race-Free Java (EPRFJ), allowing a more accurate analysis of atomicity. The paper also presents a type discovery algorithm to automatically obtain EPRFJ types, and a static interprocedural type inference algorithm that, given EPRFJ types, infers atomicity types. These algorithms can be incorporated into testing and debugging tools, benefiting users who know nothing about type systems. We report our experience with a prototype implementation.","Title: Optimized run-time race detection and atomicity checking using partial discovered types\nYear: 2005\n\nAbstract: Concurrent programs are notorious for containing errors that are difficult to reproduce and diagnose. Two common kinds of concurrency errors are data races and atomicity violations (informally, atomicity means that executing methods concurrently is equivalent to executing them serially). Several static and dynamic (run-time) analysis techniques exist to detect potential races and atomicity violations. Run-time checking may miss errors in unexecuted code and incurs significant run-time overhead. On the other hand, run-time checking generally produces fewer false alarms than static analysis; this is a significant practical advantage, since diagnosing all of the warnings from static analysis of large codebases may be prohibitively expensive.This paper explores the use of static analysis to significantly decrease the overhead of run-time checking. Our approach is based on a type system for analyzing data races and atomicity. A type discovery algorithm is used to obtain types for as much of the program as possible (complete type inference for this type system is NP-hard, and parts of the program might be untypable). Warnings from the typechecker are used to identify parts of the program from which run-time checking can safely be omitted. The approach is completely automatic, scalable to very large programs, and significantly reduces the overhead of run-time checking for data races and atomicity violations.","Title: Message race detection for web services by an SMT-based analysis\nYear: 2010\n\nAbstract: The success of the cloud computing initiative is heavily dependent on realizing trustworthy Web Services. The trustworthiness of a Web Service is judged by four factors: security, privacy, reliability and business integrity. Web Services use message-passing for communication which opens the door for messages races. Messages race with each other when their order of arrival at a destination is not guaranteed and is affected non-deterministically by factors such as network latencies and scheduling variations. Message races are dangerous to Web Services because they can be unforeseen consequences of bugs, causing messages to arrive in an unexpected ordering. In this paper we present a novel approach for improving the reliability of Web Services by detecting message races using SMT-based analysis. We model a BPEL process as a Web Service Modeling Graph (WSMG). A WSMG model is then encoded into a set of SMT constraints. The satisfiability of these constraints means that message races will occur during the actual execution of the Web Service. Hence, we reduce the message race detection problem to constraint solving problem based on satisfiability modulo theories (SMT).","Title: Classification Of Seismic Windows Using Artificial Neural Networks\nYear: 2011\n\nAbstract: We examine the plausibility of using an Artificial Neural Network (ANN) and an Importance-Aided Neural Network (IANN) for the refinement of the structural model used to create full-wave tomography images. Specifically, we apply the machine learning techniques to classifying segments of observed data wave seismograms and synthetic data wave seismograms as either usable for iteratively refining the structural model or not usable for refinement. Segments of observed and synthetic seismograms are considered usable if they are not too different, a heuristic observation made by a human expert, which is considered a match. The use of the ANN and the IANN for classification of the data wave segments removes the human computational cost of the classification process and removes the need for an expert to oversee all such classifications. Our experiments on the seismic data for Southern California have shown this technique to he promising for both classification accuracy and the reduction of the time required to compute the classification of observed data wave segment and synthetic data wave segment matches.","Title: SAM: self-adaptive dynamic analysis for multithreaded programs\nYear: 2011\n\nAbstract: Many dynamic analysis techniques have been proposed to detect incorrect program behaviors resulted from faulty code. However, the huge overhead incurred by such dynamic analysis prevents thorough testing of large-scale software systems. In this paper, we propose a novel framework using compile-time and run-time optimizations on instrumentation and monitoring that aim to significantly reduce the overhead of dynamic analysis on multithreaded programs. We implemented a tool called SAM (Self-Adaptive Monitoring) that can selectively turn off excessive monitoring on repeated code region invocations if the current program context has been determined to be redundant, which may assist many existing dynamic detection tools to improve their performance. Specifically, we approximate the program context for a code region invocation as a set of variables, which include path-critical variables and shared variables accessed in that region. The path-critical variables are inferred using a use-definition dataflow analysis, and the shared variables are identified using a hybrid thread-based escape analysis. We have implemented the tool in Java and evaluated it on a set of real-world programs. Our experimental results show that it can significantly reduce the runtime overhead of the baseline atomicity violation and data race analyses by an average of 50% and 20%, respectively, while roughly keeping the accuracy of the underlying runtime detection tools.","Title: A Performance Modeling And Optimization Analysis Tool For Sparse Matrix-Vector Multiplication On Gpus\nYear: 2014\n\nAbstract: This paper presents a performance modeling and optimization analysis tool to predict and optimize the performance of sparse matrix-vector multiplication (SpMV) on GPUs. We make the following contributions: 1) We present an integrated analytical and profile-based performance modeling to accurately predict the kernel execution times of CSR, ELL, COO, and HYB SpMV kernels. Our proposed approach is general, and neither limited by GPU programming languages nor restricted to specific GPU architectures. In this paper, we use CUDA-based SpMV kernels and NVIDIA Tesla C2050 for our performance modeling and experiments. According to our experiments, for 77 out of 82 test cases, the performance differences between the predicted and measured execution times are less than 9 percent; for the rest five test cases, the differences are between 9 and 10 percent. For CSR, ELL, COO, and HYB SpMV CUDA kernels, the average differences are 6.3, 4.4, 2.2, and 4.7 percent, respectively. 2) Based on the performance modeling, we design a dynamic-programming based SpMV optimal solution auto-selection algorithm to automatically report an optimal solution (i.e., optimal storage strategy, storage format(s), and execution time) for a target sparse matrix. In our experiments, the average performance improvements of the optimal solutions are 41.1, 49.8, and 37.9 percent, compared to NVIDIA's CSR, COO, and HYB CUDA kernels, respectively.","Title: P&P: A Combined Push-Pull Model for Resource Monitoring in Cloud Computing Environment\nYear: 2010\n\nAbstract: Cloud computing paradigm contains many shared resources, such as infrastructures, data storage, various platforms and software. Resource monitoring involves collecting information of system resources to facilitate decision making by other components in Cloud environment. It is the foundation of many major Cloud computing operations. In this paper, we extend the prevailing monitoring methods in Grid computing, namely Pull model and Push model, to the paradigm of Cloud computing. In Grid computing, we find that in certain conditions, Push model has high consistency but low efficiency, while Pull model has low consistency but high efficiency. Based on complementary properties of the two models, we propose a user-oriented resource monitoring model named Push&Pull (P&P) for Cloud computing, which employs both the above two models, and switches the two models intelligently according to users' requirements and monitored resources' status. The experimental result shows that the P&P model decreases updating costs and satisfies various users' requirements of consistency between monitoring components and monitored resources compared to the original models.","Title: Accelerating the discontinuous Galerkin method for seismic wave propagation simulations using the graphic processing unit (GPU)-single-GPU implementation\nYear: 2013\n\nAbstract: We have successfully ported an arbitrary high-order discontinuous Galerkin (ADER-DG) method for solving the three-dimensional elastic seismic wave equation on unstructured tetrahedral meshes to an Nvidia Tesla C2075 GPU using the Nvidia CUDA programming model. On average our implementation obtained a speedup factor of about 24.3 for the single-precision version of our GPU code and a speedup factor of about 12.8 for the double-precision version of our GPU code when compared with the double precision serial CPU code running on one Intel Xeon W5880 core. When compared with the parallel CPU code running on two, four and eight cores, the speedup factor of our single-precision GPU code is around 12.9, 6.8 and 3.6, respectively. In this article, we give a brief summary of the ADER-DG method, a short introduction to the CUDA programming model and a description of our CUDA implementation and optimization of the ADER-DG method on the GPU. To our knowledge, this is the first study that explores the potential of accelerating the ADER-DG method for seismic wave-propagation simulations using a GPU.","Title: Run-Time Analysis for Atomicity\nYear: 2003\n\nAbstract: Writing and debugging concurrent (shared-variable) programs is notoriously difficult. This motivated the development of numerous static analysis and run-time analysis techniques designed to (help) ensure that concurrent programs satisfy common correctness requirements for concurrent programs, such as absence of race conditions and absence of deadlocks. This paper focuses on another common correctness requirement for concurrent programs, namely, atomicity, which requires that any set of concurrent invocations of designated procedures is equivalent to performing those invocations serially in some order. Run-time analysis algorithms for detecting violations of atomicity are presented. The algorithms vary in cost and precision.","Title: HEAT: a combined approach for thread escape analysis.\nYear: 2011\n\nAbstract: Thread escape analysis can determine whether and when a variable becomes shared by multiple threads, which is a foundation for many other program analysis and software testing techniques. Most existing escape analysis tools are either purely dynamic or static analyses. Static analysis, which considers all possible behaviors of a program, may produce false positives; whereas dynamic approaches miss the information from unexecuted code sections of a program. This paper presents a hybrid approach that integrates static and dynamic analyses to address this problem. We first perform static analysis to obtain succinct summaries of accesses to all variables and interprocedural information. Dynamic analysis is then used to confirm variable sharing; for unexecuted code, we determine the sharing of variables by performing an interprocedural synthesis based on the runtime information and static summaries. Compared to dynamic analysis, the hybrid approach is able to determine the escape property of variables in unexecuted code. Compared to static analysis, the hybrid approach produces fewer false alarms. We implemented this hybrid escape analysis in Java. Our experiments on several benchmarks and real-world applications show that the hybrid approach improves the accuracy of escape analysis compared to existing approaches and significantly reduces the performance overhead of a subsequent program analysis.","Title: A Dataflow-Oriented Atomicity and Provenance System for Pipelined Scientific Workflows\nYear: 2007\n\nAbstract: Scientific workflows have gained great momentum in recent years due to their critical roles in e-Science and cyberinfrastructure applications. However, some tasks of a scientific workflow might fail during execution. A domain scientist might require a region of a scientific workflow to be \"atomic\". Data provenance, which determines the source data that are used to produce a data item, is also essential to scientific workflows. In this paper, we propose: (i) an architecture for scientific workflow management systems that supports both provenance and atomicity; (ii) a dataflow-oriented atomicity model that supports the notions of commit and abort; and (iii) a dataflow-oriented provenance model that, in addition to supporting existing provenance graphs and queries, also supports queries related to atomicity and failure.","Title: Accurate and efficient runtime detection of atomicity errors in concurrent programs\nYear: 2006\n\nAbstract: Atomicity is an important correctness condition for concurrent systems. Informally, atomicity is the property that every concurrent execution of a set of transactions is equivalent to some serial execution of the same transactions. In multi-threaded programs, executions of procedures (or methods) can be regarded as transactions. Correctness in the presence of concurrency often requires atomicity of these transactions. Tools that automatically detect atomicity violations can uncover subtle errors that are hard to find with traditional debugging and testing techniques.This paper presents new algorithms for runtime (dynamic) detection of violations of conflict-atomicity and view-atomicity, which are analogous to conflict-serializability and view-serializability in database systems. In these algorithms, the recorded events are formed into a graph with edges representing the synchronization within each transaction and possible interactions between transactions. We give conditions on the graph that imply conflict-atomicity and view-atomicity. Experiments show that these new algorithms are more efficient in most experiments and are more accurate than previous algorithms with comparable asymptotic complexity.","Title: MRGIS: A MapReduce-Enabled High Performance Workflow System for GIS\nYear: 2008\n\nAbstract: The growth of data used by data-intensive computations, e.g. geographical information systems (GIS), has far outpaced the growth of the power of a single processor. The increasing demand of data-intensive applications calls for distributed computing. In this paper, we propose a high performance workflow system MRGIS, a parallel and distributed computing platform based on MapReduce clusters, to execute GIS applications efficiently. MRGIS consists of a design interface, a task scheduler, and a runtime support system. The design interface has two options: a GUI-based workflow designer and an API-based library for programming in Python. Given a GIS workflow, the scheduler analyzes data dependencies among tasks, then dispatches them to MapReduce clusters based on the current status of the system. Our experiment demonstrates that MRGIS can significantly improve the performance of GIS workflow execution.","Title: Research on patterns of cancer markers based on cross section imaging of serum proteomic data\nYear: 2007\n\nAbstract: New proteomic technologies have brought the hope of discovering novel early cancer-specific biomarkers in complex biological samples. Novel mass spectrometry (MS) based technologies in particular, such as surface-enhanced laser desorption/ionisation time of flight (SELDI-TOF-MS), have shown promising results in recent years. To find new potential biomarkers and establish the patterns for detection of cancers, we proposed a novel method to analysis SELDI-TOF-MS using binary cross section imaging and energy curve technology. The proposed method with advantage of visualization is to mining local information adequately so as to discriminate cancer samples from non-cancer ones. Applying the procedure to MS data of proteomic analysis of serum from ovarian cancer patients and serum from cancer-free individuals in the Food and Drug Administration/National Cancer Institute Clinical Proteomics Database, we find that there are outputs of the cancerous when the threshold is above 90 and M/Z is in the range 9362.3296-9747.2723, while outputs of the non-cancerous will appear when the threshold is 60 80 and M/Z is 243.4940-247.8824.","Title: HEAT: An Integrated Static and Dynamic Approach for Thread Escape Analysis\nYear: 2009\n\nAbstract: Escape analysis can determine whether and when a variable becomes shared for multiple threads, which is a foundation for many other program analyses. Most existing escape analysis tools are either purely dynamic or static analysis. Static analysis usually considers all possible behaviors of a program, however, may produce false positives; whereas dynamic approaches can not analyze unobserved behaviors of a program. This paper presents a hybrid approach that integrates static and dynamic analyses to address this problem. We first perform static analysis to obtain summaries of accesses to potential escaped variables. When the program runs, dynamic analysis is used to confirm variable sharing; for unexecuted code, we determine the sharing of variables in it by performing an interprocedural static analysis based on the runtime information. Compared to dynamic analysis, the hybrid approach is able to determine the escape property of variables in unexecuted code. Compared to static analysis, the hybrid approach produces fewer false alarms. We implemented this hybrid escape analysis in Java. Our experimental evaluation on several benchmarks and real-world applications shows that it has improved accuracy compared to existing approaches and can also boost the performance of subsequent program analyses significantly.","Title: Symbolic Analysis of Concurrency Errors in OpenMP Programs\nYear: 2013\n\nAbstract: In this paper we present the OpenMP Analysis Toolkit (OAT), which uses Satisfiability Modulo Theories (SMT) solver based symbolic analysis to detect data races and deadlocks in OpenMP codes. Our approach approximately simulates real executions of an OpenMP program through schedule permutation. We conducted experiments on real-world OpenMP benchmarks and student homework assignments by comparing our OAT tool with two commercial dynamic analysis tools: Intel Thread Checker and Sun Thread Analyzer, and one commercial static analysis tool: Viva64 PVS Studio. The experiments show that our symbolic analysis approach is more accurate than static analysis and more efficient and scalable than dynamic analysis tools with less false positives and negatives.","Title: Static analysis of atomicity for programs with non-blocking synchronization\nYear: 2005\n\nAbstract: In concurrent programming, non-blocking synchronization is very efficient but difficult to design correctly. This paper presents a static analysis to show that code blocks are atomic, i.e., that every execution of the program is equivalent to one in which those code blocks execute without interruption by other threads. Our analysis determines commutativity of operations based primarily on how synchronization primitives (including locks, load-linked, store-conditional, and compare-and-swap) are used. A reduction theorem states that certain patterns of commutativity imply atomicity. Atomicity is itself an important correctness requirement for many concurrent programs. Furthermore, an atomic code block can be treated as a single transition during subsequent analysis of the program; this can greatly improve the efficiency of the subsequent analysis. We demonstrate the effectiveness of our approach on several concurrent non-blocking programs.","Title: An MPI-CUDA Implementation and Optimization for Parallel Sparse Equations and Least Squares (LSQR).\nYear: 2012\n\nAbstract: LSQR (Sparse Equations and Least Squares) is a widely used Krylov subspace method to solve large-scale linear systems in seismic tomography. This paper presents a parallel MPI-CUDA implementation for LSQR solver. On CUDA level, our contributions include: (1) utilize CUBLAS and CUSPARSE to compute major steps in LSQR; (2) optimize memory copy between host memory and device memory; (3) develop a CUDA kernel to perform transpose SpMV without transposing the matrix in memory or preserving additional copy. On MPI level, our contributions include: (1) decompose both matrix and vector to increase parallelism; (2) design a static load balancing strategy. In our experiment, the single GPU code achieves up to 17.6x speedup with 15.7 GFlops in single precision and 15.2x speedup with 12.0 GFlops in double precision compared with the original serial CPU code. The MPI-GPU code achieves up to 3.7x speedup with 268 GFlops in single precision and 3.8x speedup with 223 GFlops in double precision on 135 MPI tasks compared with the corresponding MPI-CPU code. The MPI-GPU code scales on both strong and weak scaling tests. In addition, our parallel implementations have better performance than the LSQR subroutine in PETSc library.","Title: A Scalable Parallel LSQR Algorithm for Solving Large-Scale Linear System for Tomographic Problems: A Case Study in Seismic Tomography.\nYear: 2013\n\nAbstract: Least Squares with QR-factorization (LSQR) method is a widely used Krylov subspace algorithm to solve sparse rectangu- lar linear systems for tomographic problems. Traditional parallel implementations of LSQR have the potential, depending on the non-zero structure of the matrix, to have significant communication cost. The communication cost can dramatically limit the scalability of the algorithm at large core counts. We describe a scalable parallel LSQR algorithm that utilizes the particular non-zero structure of matrices that occurs in tomographic problems. In particular, we specially treat the kernel component of the matrix, which is relatively dense with a random structure, and the damping component, which is very sparse and highly structured separately. The resulting algorithm has a scalable communication volume with a bounded number of communica- tion neighbors regardless of core count. We present scaling studies from real seismic tomography datasets that illustrate good scalability up to O(10, 000) cores on a Cray XT cluster.","Title: An OpenMP Analyzer for Detecting Concurrency Errors\nYear: 2012\n\nAbstract: As one of the popularparallel programming interfaces, OpenMP has been widely used in many scientific applications in order to facilitate shared-memory parallelism. With the increasing popularity of multi-core machines, more and more sequential programs are being parallelized using OpenMP. However, it is not easy for programmers to write parallel programs correctly. Concurrency errors, such as data races and deadlocks. This paper presents a novel technique to detect data races and deadlocks using hybrid program analysis. Previous work [2] has shown the symbolic execution on GPU program, our tool exploits SMT solver to detect errors in OpenMP program.","Title: SD-GIS-based temporal-spatial simulation of water quality in sudden water pollution accidents\nYear: 2011\n\nAbstract: System dynamics (SD) is well suited for studying dynamic nonlinear complex systems. In this paper, SD is applied to a rapid-onset water pollution accident using a 1-D water quality model and a conceptual GIS-SD framework is constructed to simulate the temporal-spatial changes of pollutant concentration. Based on the component GIS and the SD model, a prototype system of water quality simulation in water pollution accidents is developed. The data collected on the spot in the Songhua River water pollution accident in November 2005 were used for model parameter calibration and model validation. The results showed that: (1) the constructed model could simulate the changes of nitrobenzene concentration with time in the Songhua River water pollution accident, especially during the peak concentration and at the arrival time of peak concentration, and that the simulated values and the on-the-spot monitored values corresponded with each other well; (2) the scenario simulation could be made by adjusting parameters u (longitudinal current velocity), E (longitudinal diffusion coefficient), and k (decay rate coefficient). Such a model can provide decision makers with quantitative information to optimize related emergency response measures.","Title: CAP3: A Cloud Auto-Provisioning Framework for Parallel Processing Using On-Demand and Spot Instances\nYear: 2013\n\nAbstract: Cloud computing has drawn increasing attention from the scientific computing community due to its ease of use, elasticity, and relatively low cost. Because a high-performance computing (HPC) application is usually resource demanding, without careful planning, it can incur a high monetary expense even in Cloud. We design a tool called CAP3 (Cloud Auto-Provisioning framework for Parallel Processing) to help a user minimize the expense of running an HPC application in Cloud, while meeting the user-specified job deadline. Given an HPC application, CAP3 automatically profiles the application, builds a model to predict its performance, and infers a proper cluster size that can finish the job within its deadline while minimizing the total cost. To further reduce the cost, CAP3 intelligently chooses the Cloud's reliable on-demand instances or low-cost spot instances, depending on whether the remaining time is tight in meeting the application's deadline. Experiments on Amazon EC2 show that the execution strategy given by CAP3 is cost-effective, by choosing a proper cluster size and a proper instance type (on-demand or spot).","Title: Atomicity and provenance support for pipelined scientific workflows\nYear: 2009\n\nAbstract: Today many significant scientific discoveries are achieved through complex and distributed scientific computations that are structured and represented as scientific workflows. Although atomicity is a well studied topic in transaction processing and business workflows, such an important capability needs to be revisited in a scientific workflow environment. Firstly, the semantics of atomicity needs to be defined in a dataflow-oriented scientific workflow model, particularly for pipelined execution of hierarchical scientific workflows. Secondly, in a scientific workflow environment, atomic regions are specified or inferred dynamically as needed and are committed implicitly, which are in contrast to a priori well-defined transaction boundaries and explicit commits in transaction processing and business workflows. Finally, although atomicity and provenance are related to each other, their interactions and relationships have never been explored in the literature. In this paper, we propose: (i) an architecture for scientific workflow management systems that supports both provenance and atomicity; (ii) a dataflow-oriented atomicity model that supports the notions of commit and abort; and (iii) a dataflow-oriented provenance model that supports querying and visualizing provenance.","Title: A Cloud Computing Platform for Large-Scale Forensic Computing\nYear: 2009\n\nAbstract: The timely processing of massive digital forensic collections demands the use of large-scale distributed computing resources and the flexibility to customize the processing performed on the collections. This paper describes MPI Map Reduce (MMR), an open implementation of the Map Reduce processing model that outperforms traditional forensic computing techniques. MMR provides linear scaling for CPU-intensive processing and super-linear scaling for indexing-related workloads.","Title: The performance of replaceable linear polyacrylamide(PLA) gel electrophoresis of DNA analyzer\nYear: 2011\n\nAbstract: We report the replaceable Linear polyacrylamide(LPA) gel was synthesized in house; the inner surface of capillary was coated with the same sieving medium (LPA). The DNA analyzer which was designed by authors group to detect the samples of capillary electrophoresis (CE) with laser induced fluorescence (LIF); The data collected with indirect methods establishes confidence in the electroosmotic mobility values obtained. Constant electroosmotic mobilities of 2.5×10\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">-8</sup>\nm\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sup>\nV\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">-1</sup>\ns\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">-1</sup>\n was determined by tests. The bubbles in the LPA gel capillary electrophoresis were observed and recorded. It was discovered the bubbles can be reduced and affect CE little. A good linear CE current increase with applied field strength indicated the negligible Joule heating effects were present. This work will help to further optimize and improve high performance DNA separation in microfluidic applications.","Title: Virbase: A Resource For Virus-Host Ncrna-Associated Interactions\nYear: 2015\n\nAbstract: Increasing evidence reveals that diverse non-coding RNAs (ncRNAs) play critically important roles in viral infection. Viruses can use diverse ncRNAs to manipulate both cellular and viral gene expression to establish a host environment conducive to the completion of the viral life cycle. Many host cellular ncRNAs can also directly or indirectly influence viral replication and even target virus genomes. ViRBase ( ext-link-type=\"uri\" xlink:href=\"http://www.rna-society.org/virbase\" xlink:type=\"simple\">http://www.rna-society.org/virbase) aims to provide the scientific community with a resource for efficient browsing and visualization of virus-host ncRNA-associated interactions and interaction networks in viral infection. The current version of ViRBase documents more than 12 000 viral and cellular ncRNA-associated virus-virus, virus-host, host-virus and host-host interactions involving more than 460 non-redundant ncRNAs and 4400 protein-coding genes from between more than 60 viruses and 20 hosts. Users can query, browse and manipulate these virus-host ncRNA-associated interactions. ViRBase will be of help in uncovering the generic organizing principles of cellular virus-host ncRNA-associated interaction networks in viral infection.","Title: SMARTH: Enabling Multi-pipeline Data Transfer in HDFS\nYear: 2014\n\nAbstract: Hadoop is a popular open-source implementation of the MapReduce programming model to handle large data sets, and HDFS is one of Hadoop's most commonly used distributed file systems. Surprisingly, we found that HDFS is inefficient when handling upload of data files from client local file system, especially when the storage cluster is configured to use replicas. The root cause is HDFS's synchronous pipeline design. In this paper, we introduce an improved HDFS design called SMARTH. It utilizes asynchronous multi-pipeline data transfers instead of a single pipeline stop-and-wait mechanism. SMARTH records the actual transfer speed of data blocks and sends this information to the namenode along with periodic heartbeat messages. The namenode sorts datanodes according to their past performance and tracks this information continuously. When a client initiates an upload request, the namenode will send it a list of \\\"high performance\\\" datanodes that it thinks will yield the highest throughput for the client. By choosing higher performance datanodes relative to each client and by taking advantage of the multi-pipeline design, our experiments show that SMARTH significantly improves the performance of data write operations compared to HDFS. Specifically, SMARTH is able to improve the throughput of data transfer by 27-245% in a heterogeneous virtual cluster on Amazon EC2.","Title: Enterprise Relationship Network: Build Foundation for Social Business\nYear: 2014\n\nAbstract: Social business moves beyond linear, process-driven organizations to create new, dynamic, networked businesses that focus on customer value. Enterprise relationship network (ERN) can be used to support social business by maximizing current and future opportunities and facilitate network-enabled processes, which can lead to value co-creation. In this paper we give the specification of ERN, which links the main entities in social business together, such as enterprises, business activities, employees and products. ERN provides a set of methods for analyzing the structure of whole entities as well as a group of algorithms for exploring the patterns in these structures. We present the technique architecture of ERN and describe how the ERN supports social business. We can get a lot of valuable information from ERN, which can be used in enterprise management, employee collaborations and networked businesses. At last, through a case study on the platform of SDCMSP, we evaluate how our proposed approach supports social business and show some relationship visualization results.","Title: Runtime analysis of atomicity for multithreaded programs\nYear: 2006\n\nAbstract: Abstract—Atomicity is a correctness condition for concurrent systems. Informally, atomicity is the property that every concurrent execution of a set of transactions is equivalent to some serial execution of the same transactions. In multithreaded programs, executions,of procedures,(or methods) can be regarded,as transactions. Correctness in the presence,of concurrency,typically requires atomicity of these transactions. Tools that automatically,detect atomicity violations can uncover,subtle errors that are hard to find with traditional debugging,and testing techniques. This paper describes,two algorithms,for runtime detection of atomicity violations and compares,their cost and effectiveness. The reduction-based algorithm checks atomicity based on commutativity,properties of events in a trace; the block-based algorithm efficiently represents the relevant information about a trace as a set of blocks (i.e., pairs of events plus associated,synchronizations) and checks,atomicity by comparing,each block with other blocks. To improve,the efficiency and accuracy of both algorithms, we incorporate a multilockset algorithm for checking data races, dynamic escape analysis, and happen- before analysis. Experiments,show,that both algorithms are effective in finding atomicity violations. The block-based algorithm is more accurate,but more,expensive,than the reduction-based,algorithm. Index Terms—Concurrent programming, testing and debugging, Java, data race, atomicity. 1I NTRODUCTION","Title: Data Replication in Data Intensive Scientific Applications with Performance Guarantee\nYear: 2011\n\nAbstract: Data replication has been well adopted in data intensive scientific applications to reduce data file transfer time and bandwidth consumption. However, the problem of data replication in Data Grids, an enabling technology for data intensive applications, has proven to be NP-hard and even non approximable, making this problem difficult to solve. Meanwhile, most of the previous research in this field is either theoretical investigation without practical consideration, or heuristics-based with little or no theoretical performance guarantee. In this paper, we propose a data replication algorithm that not only has a provable theoretical performance guarantee, but also can be implemented in a distributed and practical manner. Specifically, we design a polynomial time centralized replication algorithm that reduces the total data file access delay by at least half of that reduced by the optimal replication solution. Based on this centralized algorithm, we also design a distributed caching algorithm, which can be easily adopted in a distributed environment such as Data Grids. Extensive simulations are performed to validate the efficiency of our proposed algorithms. Using our own simulator, we show that our centralized replication algorithm performs comparably to the optimal algorithm and other intuitive heuristics under different network parameters. Using GridSim, a popular distributed Grid simulator, we demonstrate that the distributed caching technique significantly outperforms an existing popular file caching technique in Data Grids, and it is more scalable and adaptive to the dynamic change of file access patterns in Data Grids.","Title: A new thermal protection approach for permanent magnet synchronous motor\nYear: 2013\n\nAbstract: This paper presents a new thermal protection approach for permanent magnet synchronous motor. Usually the thermal protection model is built based on two parameters which are thermal resistance and thermal capacitance of motor. But the stator core loss is increased significantly when the motor frequency and the motor winding temperature are increased. If the motor runs at high speed, the eddy current loss, the hysteresis loss and the harmonic current loss dominate the stator core loss. If only the thermal resistance and thermal capacitance are used for the thermal protection without considering the motor frequency, the protection model cannot response the temperature rising when the motor runs at high speed, so the motor could not be protected effectively. In this paper, the motor frequency is included in the new thermal protection approach, and the whole working speed range will be protected, and the motor lifetime will be increased.","Title: Faqs: Fast Web Service Composition Algorithm Based On Qos-Aware Sampling\nYear: 2016\n\nAbstract: Web Service Composition (WSC) has been well recognized as a convenient and flexible way of service sharing and integration in service-oriented application fields. WSC aims at selecting and composing a set of initial services with respect to the Quality of Service (QoS) values of their attributes (e.g., price), in order to complete a complex task and meet user requirements. A major research challenge of the QoS-aware WSC problem is to select a proper set of services to maximize the QoS of the composite service meeting several QoS constraints upon various attributes, e.g. total price or runtime. In this article, a fast algorithm based on QoS-aware sampling (FAQS) is proposed, which can efficiently find the near-optimal composition result from sampled services. FAQS consists of five steps as follows. 1) QoS normalization is performed to unify different metrics for QoS attributes. 2) The normalized services are sampled and categorized by guaranteeing similar number of services in each class. 3) The frequencies of the sampled services are calculated to guarantee the composed services are the most frequent ones. This process ensures that the sampled services cover as many as possible initial services. 4) The sampled services are composed by solving a linear programming problem. 5) The initial composition results are further optimized by solving a modified multi-choice multi-dimensional knapsack problem (MMKP). Experimental results indicate that FAQS is much faster than existing algorithms and could obtain stable near-optimal result.","Title: Accurate cross‒architecture performance modeling for sparse matrix‒vector multiplication (SpMV) on GPUs\nYear: 2015\n\nAbstract: This paper presents an integrated analytical and profilebased crossarchitecture performance modeling tool to specifically provide interarchitecture performance prediction for Sparse MatrixVector Multiplication (SpMV) on NVIDIA GPU architectures. To design and construct the tool, we investigate the interarchitecture relative performance for multiple SpMV kernels. For a sparse matrix, based on its SpMV kernel performance measured on a reference architecture, our crossarchitecture performance modeling tool can accurately predict its SpMV kernel performance on a target architecture. The prediction results can effectively assist researchers in making choice of an appropriate architecture that best fits their needs from a wide range of available computing architectures. We evaluate our tool with 14 widelyused sparse matrices on four GPU architectures: NVIDIA Tesla C2050, Tesla M2090, Tesla K20m, and GeForce GTX 295. In our experiments, Tesla C2050 works as the reference architecture, the other three are used as the target architectures. For Tesla M2090, the average performance differences between the predicted and measured SpMV kernel execution times for CSR, ELL, COO, and HYB SpMV kernels are 3.1%, 5.1%, 1.6%, and 5.6%, respectively. For Tesla K20m, they are 6.9%, 5.9%, 4.0%, and 6.6% on the average, respectively. For GeForce GTX 295, they are 5.9%, 5.8%, 3.8%, and 5.9% on the average, respectively. Copyright (c) 2014 John Wiley & Sons, Ltd.","Title: HBTM: A Heartbeat-based Behavior Detection Mechanism for POSIX Threads and OpenMP Applications.\nYear: 2015\n\nAbstract: Extreme-scale computing involves hundreds of millions of threads with multi-level parallelism running on large-scale hierarchical and heterogeneous hardware. In POSIX threads and OpenMP applications, some key behaviors occurring in runtime such as thread failure, busy waiting, and exit need to be accurately and timely detected. However, for the most of these applications, there are lack of unified and efficient detection mechanisms to do this. In this paper, a heartbeat-based behavior detection mechanism for POSIX threads (Pthreads) and OpenMP applications (HBTM) is proposed. In the design, two types of implementations are conducted, centralized and decentralized respectively. In both implementations, unified API has been designed to guarantee the generality of the mechanism. Meanwhile, a ring-based detection algorithm is designed to ease the burden of the centra thread at runtime. To evaluate the mechanism, the NAS Parallel Benchmarks (NPB) are used to test the performance of the HBTM. The experimental results show that the HBTM supports detection of behaviors of POSIX threads and OpenMP applications while acquiring a short latency and near 1% overhead.","Title: An Intelligent QoS Identification for Untrustworthy Web Services via Two-Phase Neural Networks\nYear: 2016\n\nAbstract: QoS identification for untrustworthy Web services is critical in QoS management in the service computing since the performance of untrustworthy Web services may result in QoS downgrade. The key issue is to intelligently learn the characteristics of trustworthy Web services from different QoS levels, then to identify the untrustworthy ones according to the characteristics of QoS metrics. As one of the intelligent identification approaches, deep neural network has emerged as a powerful technique in recent years. In this paper, we propose a novel two-phase neural network model to identify the untrustworthy Web services. In the first phase, Web services are collected from the published QoS dataset. Then, we design a feedforward neural network model to build the classifier for Web services with different QoS levels. In the second phase, we employ a probabilistic neural network (PNN) model to identify the untrustworthy Web services from each classification. The experimental results show the proposed approach has 90.5% identification ratio far higher than other competing approaches.","Title: Cloud Computing Research Analysis Using Bibliometric Method\nYear: 2015\n\nAbstract: Cloud computing has been a mainstream solution for the processing and storage of mass data, as well as an exciting area for research. As a novel business model, cloud computing has dramatically changed the provision of services and IT capacity by means of the advanced techniques. In recent years, with the increasing research interests and rapid growth of publications, some review papers provide detailed analysis on cloud computing area. In this paper, a bibliometric-based approach is presented and implemented to quantitatively review the progress in global cloud computing research with the related literature during 2007-2013 from the databases of Science Citation Index Expanded (SCI-E), Conference Proceedings Citation Index-Science (CPCI-S), and IEEEXplore. Our work is motivated by the purpose of tracing global advancement in terms of research content, geographic distribution and issue time of the related publications, rather than a specific technological area in cloud computing research. By investigating the characteristics of publications such as keywords, output, geographic distribution and affiliation, we draw some valuable conclusions to guide the further research. The experimental results show that the top 5 active research points of cloud computing concentrate on virtualization, security, mobile cloud, distributed computing, and scheduling. From the location-time aspect, China, USA, and India have published most of the papers, dominate cloud computing research and keep a high level on the international research cooperation. And there is a great increase in publication outputs especially in China and USA. Meanwhile, the analysis results demonstrate the top 3 high-cited research institutes of the University of Melbourne, University of California. Berkeley and University of Vienna in cloud computing research. The mobile cloud will be a future research hotspot and promising application field.","Title: Detecting Thread-Safety Violations in Hybrid OpenMP/MPI Programs\nYear: 2015\n\nAbstract: We propose an approach by integrating static and dynamic program analyses to detect threadsafety violations in hybrid MPI/OpenMP programs. We innovatively transform the thread-safety violation problems to race conditions problems. In our approach, the static analysis identifies a list of MPI calls related to thread-safety violations, then replaces them with our own MPI wrappers, which involve accesses to some specific shared variables. The static analysis avoids instrumenting unrelated code, which significantly reduces runtime overhead. In the dynamic analysis, both happen-before and lockset-based race detection algorithms are used to detect races on these aforementioned shared variables. By detecting races, we can identify thread-safety violations according to their specifications. Our experimental evaluation over real-world applications shows that our approach is both accurate and efficient.","Title: Dart: A Geographic Information System on Hadoop\nYear: 2015\n\nAbstract: In the field of big data research, analytics on spatio-temporal data from social media is one of the fastest growing areas and poses a major challenge on research and application. An efficient and flexible computing and storage platform is needed for users to analyze spatio-temporal patterns in huge amount of social media data. This paper introduces a scalable and distributed geographic information system, called Dart, based on Hadoop and HBase. Dart provides a hybrid table schema to store spatial data in HBase so that the Reduce process can be omitted for operations like calculating the mean center and the median center. It employs reasonable pre-splitting and hash techniques to avoid data imbalance and hot region problems. It also supports massive spatial data analysis like K-Nearest Neighbors (KNN) and Geometric Median Distribution. In our experiments, we evaluate the performance of Dart by processing 160 GB Twitter data on an Amazon EC2 cluster. The experimental results show that Dart is very scalable and efficient.","Title: A Resilient Framework for Fault Handling in Web Service Oriented Systems\nYear: 2015\n\nAbstract: Resilience is an important factor in designing web service oriented systems due to frequent failures arising in runtime. These failures derive from the stochastic and uncertainty nature of a composite web service. Service providers need to rapidly address issue when a fault occurs in system running. But it is not easy to locate and fix the faults only using the log generated by the system. In this paper, we propose a resilient framework to automatically generate a fault handling strategy for each failed service to improve the efficiency of fault handling. In the framework, we design and implement three components including exception analyzer, decision maker, and strategy selector. First, The exception analyzer builds a record, derived from the system log generated by an application, for each failed service. Next, the decision maker adopts a k-means clustering approach to construct a decision including the fault handling to each failed service in a scope. Then, the strategy selector uses an integer program solver to generate the solution to strategy selection problem that is boiled down to the optimization problem. The experiment shows that the framework can improve resilience of Web service-oriented systems under acceptable overheads, and meanwhile the accuracy of fault handling strategy is over 95%.","Title: A Novel Concurrent Generalized Deadlock Detection Algorithm in Distributed Systems.\nYear: 2015\n\nAbstract: Detecting deadlocks has been considered an important problem in distributed systems. Many approaches are proposed to handle this issue; however, little attention has been paid on coordinating concurrent execution of distributed deadlock detection algorithms. Previous approaches may report incorrect results false negatives, and they are inefficient due to lack of proper coordination of concurrent execution. In this paper, we present a novel concurrent coordination algorithm for distributed generalized deadlock detection. The proposed algorithm aims to avoid false negatives and improve the performance when concurrently executing deadlock detection in a distributed system. Our algorithm adopts diffusion computation to distribute probe messages and employs priority-based method to coordinate concurrent algorithm instances. Priority carried in the received probe messages will be locally recorded by each initiator. Instead of being suspended by higher priority algorithm instances, lower priority algorithm instances can accomplish deadlock detection locally. The initiator with the highest priority will receive and collect all related resource requests information from lower priority instances in a hierarchical manner and perform global deadlock detection at last. We evaluate our algorithm on a bunch of event-driven simulations. The experimental results show that our approach can achieve better accuracy and efficiency compared to previous approaches.","Title: Building and Analyzing of Enterprise Network: A Case Study on China Automobile Supply Network.\nYear: 2016\n\nAbstract: Social business moves beyond linear, process-driven organizations to create new, dynamic, networked businesses that focus on customer value. Enterprise network EN is used to support social business by maximizing current and future opportunities and facilitate network-enabled processes, which can lead to value co-creation. EN is a multi-level hypergraph model with enterprises, employees, products and other related entities. In this paper the authors refine the EN model and present the foundation of EN to support social businesses. Then they introduce a case study on China automobile supply network CASN. For the similarity with social networks, they verify power-law and small world theories in EN with statistical results on this data set. These theories are fitful in EN, but some new characteristics exist. The structure of EN consists of star-shaped clusters and the authors extract ego networks taking suppliers and manufacturers as the ego respectively. With the structure and distribution features of EN, they present the enterprise business similarity analysis method based on common-neighbors. And they also introduce the tentative work to detect Dunbar circles in EN. To analyze the data in a more intuitional and effective way, the authors use some data visualization tools to process the data in EN.","Title: Auto-tuning Performance of MPI Parallel Programs Using Resource Management in Container-Based Virtual Cloud\nYear: 2016\n\nAbstract: Load imbalance problem is one of the major obstacles to achieving optimal performance of High Performance Computing applications. The approach of trying to distribute the problem pieces to each node with the hope of balancing execution time has limits since the performance depends not only on data size but also on many other dynamic factors. This paper describes an approach that uses adaptive resource management enabled by the container-based virtualization to solve the load imbalance problem of MPI programs running in the cloud. Our techniques dynamically adjust CPU resource allocation to MPI processes running as container instances according to the current program execution state and system resource status. The resource allocation among MPI processes is adjusted in two ways: the intra-host level, which dynamically adjusts resources within a host, and the inter-host level, which migrates containers together with MPI processes from one host to another host. We have implemented and evaluated our approach on Amazon EC2 platform using real-world scientific benchmarks and applications, which demonstrates that the performance can be improved up to 31% (with an average of 15%) when compared with the baseline.","Title: Migrating GIS Big Data Computing from Hadoop to Spark: An Exemplary Study Using Twitter\nYear: 2016\n\nAbstract: Recent research has demonstrated that social media could provide valuable spatio-temporal data about users activities. However, information extraction and computation from big amount of data pose various challenges. To effectively process massive datasets, several platforms have been developed. Our previous study [20] explored Hadoop-based cloud computing for processing big amount of social media data [9] to study geographic distributions of social media users. In this paper, we investigate an emerging system named Spark and present a timely pilot experience on geospatial big data research. In our study, Spark has been utilized to perform some classic geospatial analyses like K-Nearest Neighbors (KNN), geographic mean and median points, and the distribution of the median points. Our design is tested on an Amazon EC2 cluster. An exemplary study using 60GB, 120GB and 180GB Twitter data has demonstrated the performance achievements by migrating computing tasks from Hadoop to Spark. In our experiments, the Spark-based solution can be up to 2.3x faster than the Hadoop-based solution due to its in-memory processing and coarse-grained resource allocation strategy. In the paper, we also discuss optimization strategies on using Spark for different geospatial computing tasks.","Title: A leader election based deadlock detection algorithm in distributed systems.\nYear: 2016\n\nAbstract: Deadlock detection is an important and challenge work in distributed systems. Thing becomes more complex when multiple deadlock detection algorithm instances executing currently in the system. In this paper, we propose a leader election based deadlock detection algorithm in distributed system. Our algorithm aims to improve the performance in the condition of concurrent execution. In addition, our algorithm can provide a certain extent of fault tolerance after a current leader fails. We have proved the liveness and safety property of our algorithm. Simulation results show that our algorithm obtains an order of magnitude performance improvement on message complexity.","Title: Rnalocate: A Resource For Rna Subcellular Localizations\nYear: 2017\n\nAbstract: Increasing evidence has revealed that RNA subcellular localization is a very important feature for deeply understanding RNA's biological functions after being transported into intra-or extra-cellular regions. RNALocate is a web-accessible database that aims to provide a high-quality RNA subcellular localization resource and facilitate future researches on RNA function or structure. The current version of RNALocate documents more than 37 700 manually curated RNA subcellular localization entries with experimental evidence, involving more than 21 800 RNAs with 42 subcellular localizations in 65 species, mainly including Homo sapiens, Mus musculus and Saccha-romyces cerevisiae etc. Besides, RNA homology, sequence and interaction data have also been integrated into RNALocate. Users can access these data through online search, browse, blast and visualization tools. In conclusion, RNALocate will be of help in elucidating the entirety of RNA subcellular localization, and developing new prediction methods.","Title: MRapid: An Efficient Short Job Optimizer on Hadoop\nYear: 2017\n\nAbstract: Data have been generated and collected at an accelerating pace. Hadoop has made analyzing large scale data much simpler to developers/analysts using commodity hardware. Interestingly, it has been shown that most Hadoop jobs have small input size and do not run for long time. For example, higher level query languages, such as Hive and Pig, would handle a complex query by breaking it into smaller adhoc ones. Although Hadoop is designed for handling complex queries with large data sets, we found that it is highly inefficient to operate at small scale data, despite a new Uber mode was introduced specifically to handle jobs with small input size. In this paper, we propose an optimized Hadoop extension called MRapid, which significantly speeds up the execution of short jobs. It is completely backward compatible to Hadoop, and imposes negligible overhead. Our experiments on Microsoft Azure public cloud show that MRapid can improve performance by up to 88% compared to the original Hadoop.","Title: Mrsim: Mitigating Reducer Skew In Mapreduce\nYear: 2017\n\nAbstract: MapReduce has emerged as a popular programming model in the field of data-intensive computing. This is due to its simplistic design, which provides ease of use for programmers, and its framework implementations such as Hadoop, which have been adopted by large business and technology companies. One significant issue in practical MapReduce applications is data skew: the imbalance in the amount of data assigned to each task. This causes some tasks to take much longer to finish than others and can significantly impact performance. Existing solutions for the data skew in reduce side increase the overhead that the users need to customize a novel partitioner for the specific application, or perform additional sampling processes before the map function begins. To mitigate the data skew in reduce side, which is called Reducer skew in this paper, we proposed a load balancing strategy based on load statistics, namely MRSIM. To gets the input data distribution in reduce stage, MRSIM computed the statistics while preparing data, which makes full use of the shuffle stage in MapReduce. To balance the load of entire cluster, MRSIM reallocated reduce tasks on the heavy nodes to idle ones according to the data distribution. In addition, by introducing the load feedback mechanism, MRSIM further improved the cluster's performance when running complex applications. We evaluated MRSIM in YARN (Hadoop 2.2.0), the experimental results show that our MRSIM outperformed the default strategy in native Hadoop greatly, the improvement in execution time reached 17%","Title: Hierarchical Spark: A Multi-Cluster Big Data Computing Framework\nYear: 2017\n\nAbstract: Nowadays, with the increasing burst of newly generated data everyday, as well as the vast expanding needs for corresponding data analyses, grand challenges have been brought to big data computing platforms. Computing resources in a single cluster are often not able to fulfill the computing capability needs. The requests of distributed computing resources are dramatically arising. In addition, with increasing popularity of cloud computing platforms, many organizations with data security concerns are more favor to hybrid cloud, a multi-cluster environment composed by both public cloud and private cloud in purpose of keeping sensitive data local. All these scenarios show great necessity of migrating big data computing to multi-cluster environment. In this paper, we present a hierarchical multi-cluster big data computing framework built upon Apache Spark. Our framework supports combination of heterogeneous Spark computing clusters. With an integrated controller within the framework, it also facilitates ability for submitting, monitoring, executing of Spark workflow. Our experimental results show that the proposed framework not only enables possibility of distributing Spark workflow throughout multiple clusters, but also provides significant performance improvement compared to single cluster environment by optimizing utilization of multi-cluster computing resources.","Title: Log-based Abnormal Task Detection and Root Cause Analysis for Spark\nYear: 2017\n\nAbstract: Application delays caused by abnormal tasks arecommon problems in big data computing frameworks. Anabnormal task in Spark, which may run slowly withouterror or warning logs, not only reduces its resident node'sperformance, but also affects other nodes' efficiency.Spark log files report neither root causes of abnormal tasks,nor where and when abnormal scenarios happen. AlthoughSpark provides a “speculation” mechanism to detect stragglertasks, it can only detect tailed stragglers in each stage. Sincethe root causes of abnormal happening are complicated, thereare no effective ways to detect root causes.This paper proposes an approach to detect abnormality andanalyzes root causes using Spark log files. Unlike commononline monitoring or analysis tools, our approach is a pureoff-line method that can analyze abnormality accurately. Ourapproach consists of four steps. First, a parser preprocessesraw log files to generate structured log data. Second, ineach stage of Spark application, we choose features relatedto execution time and data locality of each task, as well asmemory usage and garbage collection of each node. Third,based on the selected features, we detect where and whenabnormalities happen. Finally, we analyze the problems usingweighted factors to decide the probability of root causes. In thispaper, we consider four potential root causes of abnormalities,which include CPU, memory, network, and disk. The proposedmethod has been tested on real-world Spark benchmarks.To simulate various scenario of root causes, we conductedinterference injections related to CPU, memory, network,and Disk. Our experimental results show that the proposedapproach is accurate on detecting abnormal tasks as well asfinding the root causes","Title: Detecting and resolving deadlocks in mobile agent systems.\nYear: 2017\n\nAbstract: Mobile agents environment is a new application paradigm with unique features such as mobility and autonomy. Traditional deadlock detection algorithms in distributed computing systems do not work well in mobile agent systems due to the unique feature property of the mobile agent. Existing deadlock detection and resolution algorithms in mobile agent systems have limitations such as performance inefficiency and duplicate detection/resolution when multiple mobile agents simultaneously detect/resolve the same deadlock. To address these problems, we propose an improved deadlock detection and resolution algorithm that adopts priority-based technique and lazy reaction strategy. The priority-based technique aims to ensure that there is only one instance of deadlock detection and resolution, and it also helps reduce mobile agent movement and data traffic together with the lazy reaction strategy. The liveness and safety properties of the proposed algorithm are proved in this paper. Theoretical analysis and experimental results show that the proposed algorithm provides better performance in terms of agent movement, data traffic, and execution time.","Title: ISAT: An intelligent Web service selection approach for improving reliability via two-phase decisions.\nYear: 2018\n\nAbstract: Due to stochasticity and uncertainty of malicious Web services over the Internet, it becomes difficult to select reliable services while meeting non-functional requirements in service-oriented systems. To avoid the unreliable real-world process of obtaining services, this paper proposes a novel service selection approach via two-phase decisions for enhancing the reliability of service-oriented systems. In the first-phase decision, we define the problem of finding reliable service candidates as a multiple criteria decision making (MCDM) problem. Then, we construct a decision model to address the problem. In the second-phase decision, we define the problem of selecting services based on non-functional requirements as an optimization problem. Finally, we propose a convex hull based approach for solving the optimization problem. Large-scale and real-world experiments are conducted to show the advantages of the proposed approach. The evaluation results confirm that our approach achieves higher success rate and less computation time to guarantee the reliability when compared to the other state-of-the-art approaches.","Title: A Semi-Supervised Two-Stage Approach To Learning From Noisy Labels\nYear: 2018\n\nAbstract: The recent success of deep neural networks is powered in part by large-scale well-labeled training data. However, it is a daunting task to laboriously annotate an ImageNet-like dateset. On the contrary, it is fairly convenient, fast, and cheap to collect training images from the Web along with their noisy labels. This signifies the need of alternative approaches to training deep neural networks using such noisy labels. Existing methods tackling this problem either try to identify and correct the wrong labels or reweigh the data terms in the loss function according to the inferred noisy rates. Both strategies inevitably incur errors for some of the data points. In this paper, we contend that it is actually better to ignore the labels of some of the data points than to keep them if the labels are incorrect, especially when the noisy rate is high. After all, the wrong labels could mislead a neural network to a bad local optimum. We suggest a two-stage framework for the learning from noisy labels. In the first stage, we identify a small portion of images from the noisy training set of which the labels are correct with a high probability. The noisy labels of the other images are ignored. In the second stage, we train a deep neural network in a semi-supervised manner. This framework effectively takes advantage of the whole training set and yet only a portion of its labels that are most likely correct. Experiments on three datasets verify the effectiveness of our approach especially when the noisy rate is high.","Title: Optimizing MapReduce Partitioner Using Naive Bayes Classifier.\nYear: 2017\n\nAbstract: Data locality and data skew on the reduce side are two essential issues in MapReduce. Improving data locality can decrease network traffic by moving reduce tasks to the nodes where the input data of reduce tasks is located. Data skew will lead to load imbalance among reducer nodes. Partitioning is an important operation of MapReduce because it determines the destinations of map output and could significantly affect the data amount of shuffle. Therefore, an effective partitioner can improve MapReduce performance by increasing data locality and decreasing data skew on the reduce side. Previous studies considering the two essential issues have ignored the fact that for different types of jobs, the priority of data locality and data skew on the reduce side may produce different effects on the execution time. In this paper, we propose a novel partitioner based on naive Bayes classifier, namely, BAPM, which achieves better performance through optimizing data locality and data skew by leveraging the naive Bayes classifier, i.e., considering job type and bandwidth as classification attributes. Our experiments are performed in a Hadoop cluster with 31 nodes and the results show that BAPM speeds up the computing performance of MapReduce by up to 19.26% compared to the native Hadoop.","Title: Improving the Improved Training of Wasserstein GANs: A Consistency Term and Its Dual Effect.\nYear: 2018\n\nAbstract: Despite being impactful on a variety of problems and applications, the generative adversarial nets (GANs) are remarkably difficult to train. This issue is formally analyzed by cite{arjovsky2017towards}, who also propose an alternative direction to avoid the caveats in the minmax two-player training of GANs. The corresponding algorithm, namely, Wasserstein GAN (WGAN) hinges on the 1-Lipschitz continuity of the discriminators. In this paper, we propose a novel approach for enforcing the Lipschitz continuity in the training procedure of WGANs. Our approach seamlessly connects WGAN with one of the recent semi-supervised learning approaches. As a result, it gives rise to not only better photo-realistic samples than the previous methods but also state-of-the-art semi-supervised learning results. In particular, to the best of our knowledge, our approach gives rise to the inception score of more than 5.0 with only 1,000 CIFAR10 images and is the first that exceeds the accuracy of 90% the CIFAR10 datasets using only 4,000 labeled images.","Title: Public Opinion Spamming: A Model for Content and Users on Sina Weibo.\nYear: 2018\n\nAbstract: Microblogs serve hundreds of millions of active users, but have also attracted large numbers of spammers. While traditional spam often seeks to endorse specific products or services, nowadays there are increasingly also paid posters intent on promoting particular views on hot topics and influencing public opinion. In this work, we fill an important research gap by studying how to detect such opinion spammers and their micro-manipulation of public opinion. Our model is unsupervised and adopts a Bayesian framework to distinguish spammers from other classes of users. Experiments on a Sina Weibo hot topic dataset demonstrate the effectiveness of the proposed approach. A further diachronic analysis of the collected data demonstrates that public opinion spammers have developed sophisticated techniques and have seen success in subtly manipulating the public sentiment.","Title: Tuning Performance of Spark Programs\nYear: 2018\n\nAbstract: Along with the explosive growth of data, there is a great demand to speedup the ability to process them. Although there are several platforms such as Spark that have made analysis easier to developers, the performance tuning for such platforms meanwhile becomes complex. In this paper, we propose an efficient performance optimization engine called Hedgehog to evaluate the performance based on \"Law of Diminishing Marginal Utility\" and give an optimal configuration setting. The initial experiments show that our optimization can gain 19.6% performance improvement compared to the naive configuration by tuning only 3 parameters.","Title: NPIY : A novel partitioner for improving mapreduce performance.\nYear: 2018\n\nAbstract: MapReduce is an effective and widely-used framework for processing large datasets in parallel over a cluster of computers. Data skew, cluster heterogeneity, and network traffic are three issues that significantly affect the performance of MapReduce applications. However, the hash-based partitioner in the native Hadoop does not consider these factors. This paper proposes a new partitioner for Yarn (Hadoop 2.6.0), namely, NPIY, which adopts an innovative parallel sampling method to distribute intermediate data. The paper makes the following major contributions: (1) NPIY mitigates data skew in MapReduce applications; (2) NPIY considers the heterogeneity of computing resources to balance the loads among Reducers; (3) NPIY reduces the network traffic in the shuffle phase by trying to retain intermediate data on those nodes running both map and reduce tasks. Compared with the native Hadoop and other popular strategies, NPIY can reduce execution time by up to 41.66% and 58.68% in homogeneous and heterogeneous clusters, respectively. We further customize NPIY for parallel image processing, and the execution time has been improved by 28.8% compared with the native Hadoop.","Title: A fault tolerant election-based deadlock detection algorithm in distributed systems\nYear: 2018\n\nAbstract: Deadlock detection in a distributed system without shared memory is important to ensure the reliability of the system. It becomes more complex when multiple deadlock detection algorithm instances execute concurrently in the system. In addition, the problem of communication disconnection between computing nodes or processes makes deadlock detection more difficult. Existing centralized algorithms suffer from single point failure of the central controller (due to communication disconnection), and they are performance-inefficient in the case of concurrent execution. In this paper, we extend our previous work (Lu et al. ) and propose a fault tolerant deadlock detection algorithm in distributed systems. The extended proposed algorithm can tolerate a certain extent of communication disconnection between computing nodes or processes. A central controller is used to collect requesting conditions, construct a wait-for graph, and detect deadlocks. The proposed algorithm can select a new central controller if the current central leader fails due to communication disconnections. The liveness and safety properties of the proposed algorithm are proved in this paper. Experimental results show that the proposed algorithm provides better performance than most of existing algorithms in terms of message number, data traffic, and execution time. In addition, the proposed algorithm provides additional fault tolerance compared to existing deadlock detection algorithms in the case of communication disconnection.","Title: Five Shades of Untruth: Finer-Grained Classification of Fake News.\nYear: 2018\n\nAbstract: Prior work on algorithmic truth assessment on unreliable content, has mostly pursued binary classifiers - factual vs. fake - and disregarded the finer shades of untruth. On the other hand, manual analysis of questionable content has proposed a more fine-grained classification: distinguishing between hoaxes, irony and propaganda, or the six-way rating by the PolitiFact community. In this paper, we present a principled approach to capture these finer shades in automatically assessing and classifying news articles and claims. We systematically explore a variety of signals from both news and social media, and give an analysis of the underlying features.","Title: Detecting Anomaly in Big Data System Logs Using Convolutional Neural Network\nYear: 2018\n\nAbstract: Nowadays, big data systems are being widely adopted by many domains for offering effective data solutions, such as manufacturing, healthcare, education, and media. Big data systems produce tons of unstructured logs that contain buried valuable information. However, it is a daunting task to manually unearth the information and detect system anomalies. A few automatic methods have been developed, where the cutting-edge machine learning technique is one of the most promising ways. In this paper, we propose a novel approach for anomaly detection from big data system logs by leveraging Convolutional Neural Networks (CNN). Different from other existing statistical methods or traditional rule-based machine learning approaches, our CNN-based model can automatically learn event relationships in system logs and detect anomaly with high accuracy. Our deep neural network consists of logkey2vec embeddings, three 1D convolutional layers, dropout layer, and max-pooling. According to our experiment, our CNN-based approach has better accuracy(reaches to 99%) compared to other approaches using Long Short term memory (LSTM) and Multilayer Perceptron (MLP) on detecting anomaly in Hadoop Distributed File System (HDFS) logs.","Title: Ftsgd: An Adaptive Stochastic Gradient Descent Algorithm For Spark Mllib\nYear: 2018\n\nAbstract: The proliferation of massive datasets and the surge of interests in big data analytics have popularized a number of novel distributed data processing platforms such as Hadoop and Spark. Their large and growing ecosystems of libraries enable even novice to take advantage of the latest data analytics and machine learning algorithms. However, time-consuming data synchronization and communications in iterative algorithms on large-scale distributed platforms can lead to significant performance inefficiency. MLlib is Spark's scalable library consisting of common machine learning algorithms, many of which employ Stochastic Gradient Descent (SGD) to find minima or maxima by iterations. However, the convergence can be very slow if gradient data are synchronized on each iteration.In this work, we optimize the current implementation of SGD in Spark's MLlib by reusing data partition for multiple times within a single iteration to find better candidate weights in a more efficient way. Whether using multiple local iterations within each partition is dynamically decided by the 68-95-99.7 rule. We also design a variant of momentum algorithm to optimize step size in every iteration. This method uses a new adaptive rule that decreases the step size whenever neighboring gradients show differing directions of significance. Experiments show that our adaptive algorithm is more efficient and can be 7 times faster compared to the original MLlib's SGD.","Title: A Proximal Zeroth-Order Algorithm for Nonconvex Nonsmooth Problems.\nYear: 2018\n\nAbstract: In this paper, we focus on solving an important class of nonconvex optimization problems which includes many problems for example signal processing over a networked multi-agent system and distributed learning over networks. Motivated by many applications in which the local objective function is the sum of smooth but possibly nonconvex part, and non-smooth but convex part subject to a linear equality constraint, this paper proposes a proximal zeroth-order primal dual algorithm (PZO-PDA) that accounts for the information structure of the problem. This algorithm only utilize the zeroth-order information (i.e., the functional values) of smooth functions, yet the flexibility is achieved for applications that only noisy information of the objective function is accessible, where classical methods cannot be applied. We prove convergence and rate of convergence for PZO-PDA. Numerical experiments are provided to validate the theoretical results.","Title: Localized Video Coding\nYear: 2019\n\nAbstract: This paper describes a novel scheme of video coding structure called Localized Video Coding (LVC) infra structure. Unlike the existing video coding standards, LVC is a video coding structure that is parallel-friendly. LVC will divide a video sequence into several sub-sequences and process them independently. LVC is a nontraditional way to parallelize video coding process, aimed at solving the existing problems of heat dissipation in chips. Every sub-sequence can be coded or decoded in a different processing unit and LVC can control a processing unit to sleep or work. Hence we can easily transfer the tasks from an overheated processing unit to a normal one. In this paper we will illustrate the LVC structure and show the results. Then we will provide an example of an improved method that shows a massive reduction in the processing time of a whole video sequence as well an encouraging video coding performance compared with the HEVC Tiles [1].","Title: A Reinforcement Learning Based Resource Management Approach for Time-critical Workloads in Distributed Computing Environment\nYear: 2018\n\nAbstract: Many data analyzing applications highly rely on timely response from execution, and are referred as time-critical data analyzing applications. Due to frequent appearing of gigantic amount of data and analytical computations, running them on large scale distributed computing environments is often advantageous. The workload of big data applications is often hybrid, i.e., contains a combination of time-critical and regular non-time-critical applications. Resource management for hybrid workloads in complex distributed computing environment is becoming more critical and needs more studies. However, it is difficult to design rule-based approaches best suited for such complex scenarios because many complicated characteristics need to be taken into account.Therefore, we present an innovative reinforcement learning (RL) based resource management approach for hybrid workloads in distributed computing environment. We utilize neural networks to capture desired resource management model, use reinforcement learning with designed value definition to gradually improve the model and use ε-greedy methodology to extend exploration along the reinforcement process. The extensive experiments show that our obtained resource management solution through reinforcement learning is able to greatly surpass the baseline rule-based models. Specifically, the model is good at reducing both the missing deadline occurrences for time-critical applications and lowering average job delay for all jobs in the hybrid workloads. Our reinforcement learning based approach has been demonstrated to be able to provide an efficient resource manager for desired scenarios.","Title: Aet Vs. Aed: Unsupervised Representation Learning By Auto-Encoding Transformations Rather Than Data\nYear: 2019\n\nAbstract: The success of deep neural networks often relies on a large amount of labeled examples, which can be difficult to obtain in many real scenarios. To address this challenge, unsupervised methods are strongly preferred for training neural networks without using any labeled data. In this paper, we present a novel paradigm of unsupervised representation learning by Auto-Encoding Transformation (AET) in contrast to the conventional Auto-Encoding Data (AED) approach. Given a randomly sampled transformation, AET seeks to predict it merely from the encoded features as accurately as possible at the output end. The idea is the following: as long as the unsupervised features successfully encode the essential information about the visual structures of original and transformed images, the transformation can be well predicted. We will show that this AET paradigm allows us to instantiate a large variety of transformations, from parameterized, to non-parameterized and GAN-induced ones. Our experiments show that AET greatly improves over existing unsupervised approaches, setting new state-of-the-art performances being greatly closer to the upper bounds by their fully supervised counterparts on CIFAR-10, ImageNet and Places datasets.","Title: Texture and Position Based Multiple Transform for Inter-Predicted Residue Coding\nYear: 2018\n\nAbstract: The next generation video coding standard beyond HEVC is in the study. Many efficient coding tools are introduced to the hybrid framework. Among the new coding tools, EMT focuses on transform module by multiple transform modes to improve the transform efficiency. However, EMT is implemented on residual blocks ignoring the details of the residual distribution. Hence, EMT has some drawbacks to be repaired. In this paper, we propose a method, named texture and position based multiple transform (TPBMT), to refine EMT in the framework. What's more, the efficiency of TPBMT is verified by sufficient experimental data. When implemented on JEM7.0, TPBMT attains average 1.26%, 1.66% and 1.62% for Y, U and V, respectively, up to 6.07%, 5.19% and 4.87%.","Title: Naive Bayes Classifier Based Partitioner For Mapreduce\nYear: 2018\n\nAbstract: MapReduce is an effective framework for processing large datasets in parallel over a cluster. Data locality and data skew on the reduce side are two essential issues in MapReduce. Improving data locality can decrease network traffic by moving reduce tasks to the nodes where the reducer input data is located. Data skew will lead to load imbalance among reducer nodes. Partitioning is an important feature of MapReduce because it determines the reducer nodes to which map output results will be sent. Therefore, an effective partitioner can improve MapReduce performance by increasing data locality and decreasing data skew on the reduce side. Previous studies considering both essential issues can be divided into two categories: those that preferentially improve data locality, such as LEEN, and those that preferentially improve load balance, such as CLP. However, all these studies ignore the fact that for different types of jobs, the priority of data locality and data skew on the reduce side may produce different effects on the execution time. In this paper, we propose a naive Bayes classifier based partitioner, namely, BAPM, which achieves better performance because it can automatically choose the proper algorithm (LEEN or CLP) by leveraging the naive Bayes classifier, i.e., considering job type and bandwidth as classification attributes. Our experiments are performed in a Hadoop cluster, and the results show that BAPM boosts the computing performance of MapReduce. The selection accuracy reaches 95.15%. Further, compared with other popular algorithms, under specific bandwidths, the improvement BAPM achieved is up to 31.31%.","Title: Energy Efficiency Optimization with CoMP in Homogeneous Network of TD-LTE-A System\nYear: 2017\n\nAbstract: Coordinated Multiple Point (CoMP) Transmission/Reception could increase the transmission date rate of cell edge users and extend the cell coverage. Meanwhile, to meet the requirement of green communications, the researchers have studied how to improve the energy efficiency. In this paper, the energy consumption of eNodeB in CoMP is analyzed and the energy efficiency is optimized. Then, the joint optimization of resource allocation, beamforming and power allocation is performed to maximize the energy efficiency in CoMP homogeneous networks. The relationship between system energy efficiency and system spectrum efficiency is also discussed in this paper.","Title: Cpgavas2, An Integrated Plastome Sequence Annotator And Analyzer\nYear: 2019\n\nAbstract: We previously developed a web server CPGAVAS for annotation, visualization and GenBank submission of plastome sequences. Here, we upgrade the server into CPGAVAS2 to address the following challenges: (i) inaccurate annotation in the reference sequence likely causing the propagation of errors; (ii) difficulty in the annotation of small exons of genes petB, petD and rps16 and trans-splicing gene rps12; (iii) lack of annotation for other genome features and their visualization, such as repeat elements; and (iv) lack of modules for diversity analysis of plastomes. In particular, CPGAVAS2 provides two reference datasets for plastome annotation. The first dataset contains 43 plastomes whose annotation have been validated or corrected by RNA-seq data. The second one contains 2544 plastomes curated with sequence alignment. Two new algorithms are also implemented to correctly annotate small exons and trans-splicing genes. Tandem and dispersed repeats are identified, whose results are displayed on a circular map together with the annotated genes. DNA-seq and RNA-seq data can be uploaded for identification of single-nucleotide polymorphism sites and RNA-editing sites. The results of two case studies show that CPGAVAS2 annotates better than several other servers. CPGAVAS2 will likely become an indispensible tool for plastome research and can be accessed from http://www.herbalgenomics.org/cpgavas2.","Title: Learning to Adaptively Scale Recurrent Neural Networks.\nYear: 2019\n\nAbstract: Recent advancements in recurrent neural network (RNN) research have demonstrated the superiority of utilizing multiscale structures in learning temporal representations of time series. Currently, most of multiscale RNNs use fixed scales, which do not comply with the nature of dynamical temporal patterns among sequences. In this paper, we propose Adaptively Scaled Recurrent Neural Networks (ASRNN), a simple but efficient way to handle this problem. Instead of using predefined scales, ASRNNs are able to learn and adjust scales based on different temporal contexts, making them more flexible in modeling multiscale patterns. Compared with other multiscale RNNs, ASRNNs are bestowed upon dynamical scaling capabilities with much simpler structures, and are easy to be integrated with various RNN cells. The experiments on multiple sequence modeling tasks indicate ASRNNs can efficiently adapt scales based on different sequence contexts and yield better performances than baselines without dynamical scaling abilities.","Title: Depthwise Convolution is All You Need for Learning Multiple Visual Domains.\nYear: 2019\n\nAbstract: There is a growing interest in designing models that can deal with images from different visual domains. If there exists a universal structure in different visual domains that can be captured via a common parameterization, then we can use a single model for all domains rather than one model per domain. A model aware of the relationships between different domains can also be trained to work on new domains with less resources. However, to identify the reusable structure in a model is not easy. In this paper, we propose a multi-domain learning architecture based on depthwise separable convolution. The proposed approach is based on the assumption that images from different domains share cross-channel correlations but have domain-specific spatial correlations. The proposed model is compact and has minimal overhead when being applied to new domains. Additionally, we introduce a gating mechanism to promote soft sharing between different domains. We evaluate our approach on Visual Decathlon Challenge, a benchmark for testing the ability of multi-domain models. The experiments show that our approach can achieve the highest score while only requiring 50% of the parameters compared with the state-of-the-art approaches.","Title: LADRA: Log-based abnormal task detection and root-cause analysis in big data processing with Spark\nYear: 2019\n\nAbstract: As big data processing is being widely adopted by many domains, massive amount of generated data become more reliant on the parallel computing platforms for analysis, wherein Spark is one of the most widely used frameworks. Spark’s abnormal tasks may cause significant performance degradation, and it is extremely challenging to detect and diagnose the root causes. To that end, we propose an innovative tool, named LADRA, for log-based abnormal tasks detection and root-cause analysis using Spark logs. In LADRA, a log parser first converts raw log files into structured data and extracts features. Then, a detection method is proposed to detect where and when abnormal tasks happen. In order to analyze root causes we further extract pre-defined factors based on these features. Finally, we leverage General Regression Neural Network (GRNN) to identify root causes for abnormal tasks. The likelihood of reported root causes are presented to users according to the weighted factors by GRNN. LADRA is an off-line tool that can accurately analyze abnormality without extra monitoring overhead. Four potential root causes, i.e., CPU, memory, network, and disk I/O, are considered. We have tested LADRA atop of three Spark benchmarks by injecting aforementioned root causes. Experimental results show that our proposed approach is more accurate in the root cause analysis than other existing methods.","Title: NATTACK: Learning the Distributions of Adversarial Examples for an Improved Black-Box Attack on Deep Neural Networks.\nYear: 2019\n\nAbstract: Powerful adversarial attack methods are vital for understanding how to construct robust deep neural networks (DNNs) and for thoroughly testing defense techniques. In this paper, we propose a black-box adversarial attack algorithm that can defeat both vanilla DNNs and those generated by various defense techniques developed recently. Instead of searching for an optimal adversarial example for a benign input to a targeted DNN, our algorithm finds a probability density distribution over a small region centered around the input, such that a sample drawn from this distribution is likely an adversarial example, without the need of accessing the DNNu0027s internal layers or weights. Our approach is universal as it can successfully attack different neural networks by a single algorithm. It is also strong; according to the testing against 2 vanilla DNNs and 13 defended ones, it outperforms state-of-the-art black-box or white-box attack methods for most test cases. Additionally, our results reveal that adversarial training remains one of the best defense techniques, and the adversarial examples are not as transferable across defended DNNs as them across vanilla DNNs.","Title: Frame-Recurrent Video Inpainting by Robust Optical Flow Inference.\nYear: 2019\n\nAbstract: In this paper, we present a new inpainting framework for recovering missing regions of video frames. Compared with image inpainting, performing this task on video presents new challenges such as how to preserving temporal consistency and spatial details, as well as how to handle arbitrary input video size and length fast and efficiently. Towards this end, we propose a novel deep learning architecture which incorporates ConvLSTM and optical flow for modeling the spatial-temporal consistency in videos. It also saves much computational resource such that our method can handle videos with larger frame size and arbitrary length streamingly in real-time. Furthermore, to generate an accurate optical flow from corrupted frames, we propose a robust flow generation module, where two sources of flows are fed and a flow blending network is trained to fuse them. We conduct extensive experiments to evaluate our method in various scenarios and different datasets, both qualitatively and quantitatively. The experimental results demonstrate the superior of our method compared with the state-of-the-art inpainting approaches.","Title: Robust Sparse Regularization: Simultaneously Optimizing Neural Network Robustness and Compactness.\nYear: 2019\n\nAbstract: Deep Neural Network (DNN) trained by the gradient descent method is known to be vulnerable to maliciously perturbed adversarial input, aka. adversarial attack. As one of the countermeasures against adversarial attack, increasing the model capacity for DNN robustness enhancement was discussed and reported as an effective approach by many recent works. In this work, we show that shrinking the model size through proper weight pruning can even be helpful to improve the DNN robustness under adversarial attack. For obtaining a simultaneously robust and compact DNN model, we propose a multi-objective training method called Robust Sparse Regularization (RSR), through the fusion of various regularization techniques, including channel-wise noise injection, lasso weight penalty, and adversarial training. We conduct extensive experiments across popular ResNet-20, ResNet-18 and VGG-16 DNN architectures to demonstrate the effectiveness of RSR against popular white-box (i.e., PGD and FGSM) and black-box attacks. Thanks to RSR, 85% weight connections of ResNet-18 can be pruned while still achieving 0.68% and 8.72% improvement in clean- and perturbed-data accuracy respectively on CIFAR-10 dataset, in comparison to its PGD adversarial training baseline.","Title: A Novel Derived Mode for Block Partitioning Structure in Video Coding\nYear: 2019\n\nAbstract: In the exploration of the next video coding standard, the quadtree plus binary tree block structure (QTBT) has been adopted in the joint video exploration team. QTBT splits a block into sub-blocks following a structure of quadtree or binary tree. However, all the split modes of QTBT are symmetrical, which is less efficient in coding asymmetrical motion. In addition, the lower signaling efficiency of side information occurs when a successive binary split in the same direction is selected. Motivated by these observations, the derived mode (DM) based on QTBT is proposed in this letter, where six novel DMs are introduced. The DM further splits a QTBT node into several sub-blocks, and each sub-block can be predicted independently. Among the DMs, four asymmetrical split modes are introduced to improve the capability of coding asymmetrical motion, and two 4-split modes are designed to improve signaling efficiency. Moreover, higher efficiency than QTBT, a 0.99% BD-rate saving on average, is verified by extensive experiments.","Title: Defending Against Adversarial Attacks Using Random Forest\nYear: 2019\n\nAbstract: As deep neural networks (DNNs) have become increasingly important and popular, the robustness of DNNs is the key to the safety of both the Internet and physical world. Unfortunately, some recent studies show that adversarial examples, which are hard to be distinguished from real examples, can easily fool DNNs and manipulate their predictions. Upon observing that adversarial examples are mostly generated by gradient-based methods, in this paper, we first propose to use a simple yet very effective non-differentiable hybrid model that combines DNNs and random forests, rather than hide gradients from attackers, to defend against the attacks. Our experiments show that our model can successfully and completely defend the white-box attacks, has a lower transferability, and is quite resistant to three representative types of black-box attacks; while at the same time, our model achieves similar classification accuracy as the original DNNs. Finally, we investigate and suggest a criterion to define where to grow random forests in DNNs.","Title: Analyzing Deep Neural Network'S Transferability Via Frechet Distance\nYear: 2021\n\nAbstract: Transfer learning has become the de facto practice to reuse a deep neural network (DNN) that is pre-trained with abundant training data in a source task to improve the model training on target tasks with smaller-scale training data. In this paper, we first investigate the correlation between the DNN's pre-training performance in the source task and their transfer results in the downstream tasks. We find that high performance of a pre-trained model does not necessarily imply high transferability. We then propose a metric, named Frechet Pre-train Distance, to estimate the transferability of a deep neural network. By applying the proposed Frechet Pre-train Distance, we are able to identify the optimal pre-trained checkpoint, and then achieve high transferability on downstream tasks. Finally, we investigate several factors impacting DNN's transferability including normalization, different networks and learning rates. The results consistently support our conclusions.","Title: SODA: A Semantics-Aware Optimization Framework for Data-Intensive Applications Using Hybrid Program Analysis\nYear: 2021\n\nAbstract: In the era of data explosion, a growing number of data-intensive computing frameworks, such as Apache Hadoop and Spark, have been proposed to handle the massive volume of unstructured data in parallel. Since programming models provided by these frameworks allow users to specify complex and diversified user-defined functions (UDFs) with predefined operations, the grand challenge of tuning up entire...","Title: A Lazy Approach to Long-Horizon Gradient-Based Meta-Learning.\nYear: 2021\n\nAbstract: Gradient-based meta-learning relates task-specific models to a meta-model by gradients. By this design, an algorithm first optimizes the task-specific models by an inner loop and then backpropagates meta-gradients through the loop to update the meta-model. The number of inner-loop optimization steps has to be small (e.g., one step) to avoid high-order derivatives, big memory footprints, and the risk of vanishing or exploding meta-gradients. We propose an intuitive teacher-student scheme to enable the gradient-based meta-learning algorithms to explore long horizons by the inner loop. The key idea is to employ a student network to adequately explore the search space of task-specific models (e.g., by more than ten steps), and a teacher then takes a\"leap\"toward the regions probed by the student. The teacher not only arrives at a high-quality model but also defines a lightweight computation graph for meta-gradients. Our approach is generic; it performs well when applied to four meta-learning algorithms over three tasks: few-shot learning, long-tailed classification, and meta-attack.","Title: CTIN: Robust Contextual Transformer Network for Inertial Navigation.\nYear: 2022\n\nAbstract: Recently, data-driven inertial navigation approaches have demonstrated their capability of using well-trained neural networks to obtain accurate position estimates from inertial measurement units (IMUs) measurements. In this paper, we propose a novel robust Contextual Transformer-based network for Inertial Navigation (CTIN) to accurately predict velocity and trajectory. To this end, we first design a ResNet-based encoder enhanced by local and global multi-head self-attention to capture spatial contextual information from IMU measurements. Then we fuse these spatial representations with temporal knowledge by leveraging multi-head attention in the Transformer decoder. Finally, multi-task learning with uncertainty reduction is leveraged to improve learning efficiency and prediction accuracy of velocity and trajectory. Through extensive experiments over a wide range of inertial datasets (e.g., RIDI, OxIOD, RoNIN, IDOL, and our own), CTIN is very robust and outperforms state-of-the-art models.","Title: ADCNN: Towards learning adaptive dilation for convolutional neural networks\nYear: 2022\n\nAbstract: Dilated convolution kernels are constrained by their shared dilation, keeping them from being aware of diverse spatial contents at different locations. We address such limitations by formulating the dilation as trainable weights with respect to individual positions. We propose Adaptive Dilation Convolutional Neural Networks (ADCNN), a light-weighted extension that allows convolutional kernels to adjust their dilation value based on different contents at the pixel level. Unlike previous content-adaptive models, ADCNN dynamically infers pixel-wise dilation via modeling feed-forward inter-patterns, which provides a new perspective for developing adaptive network structures other than sampling kernel spaces. Our evaluation results indicate ADCNNs can be easily integrated into various backbone networks and consistently outperform their regular counterparts on various visual tasks.","Title: Multi-stream dynamic video Summarization\nYear: 2022\n\nAbstract: With vast amounts of video content being uploaded to the Internet every minute, video summarization becomes critical for efficient browsing, searching, and indexing of visual content. Nonetheless, the spread of social and egocentric cameras creates an abundance of sparse scenarios captured by several devices, and ultimately required to be jointly summarized. In this paper, we discuss the problem of summarizing videos recorded independently by several dynamic cameras that intermittently share the field of view. We present a robust framework that (a) identifies a diverse set of important events among moving cameras that often are not capturing the same scene, and (b) selects the most representative view(s) at each event to be included in a universal summary. Due to the lack of an applicable alternative, we collected a new multi-view egocentric dataset, Multi-Ego. Our dataset is recorded simultaneously by three cameras, covering a wide variety of real-life scenarios. The footage is annotated by multiple individuals under various summarization configurations, with a consensus analysis ensuring a reliable ground truth. We conduct extensive experiments on the compiled dataset in addition to three other standard benchmarks that show the robustness and the advantage of our approach in both supervised and unsupervised settings. Additionally, we show that our approach learns collectively from data of varied number-of-views and orthogonal to other summarization methods, deeming it scalable and generic.","Title: Unifying Obstacle Detection, Recognition, and Fusion Based on the Polarization Color Stereo Camera and LiDAR for the ADAS\nYear: 2022\n\nAbstract: The perception module plays an important role in vehicles equipped with advanced driver-assistance systems (ADAS). This paper presents a multi-sensor data fusion system based on the polarization color stereo camera and the forward-looking light detection and ranging (LiDAR), which achieves the multiple target detection, recognition, and data fusion. The You Only Look Once v4 (YOLOv4) network is utilized to achieve object detection and recognition on the color images. The depth images are obtained from the rectified left and right images based on the principle of the epipolar constraints, then the obstacles are detected from the depth images using the MeanShift algorithm. The pixel-level polarization images are extracted from the raw polarization-grey images, then the water hazards are detected successfully. The PointPillars network is employed to detect the objects from the point cloud. The calibration and synchronization between the sensors are accomplished. The experiment results show that the data fusion enriches the detection results, provides high-dimensional perceptual information and extends the effective detection range. Meanwhile, the detection results are stable under diverse range and illumination conditions.","Title: Continuous sliding mode control for the translational oscillator with a rotating actuator system\nYear: 2022\n\nAbstract: The stabilization and disturbance rejection of the translational oscillator with a rotating actuator (TORA) are considered in this paper. To deal with the control issues, a novel continuous sliding mode control method is designed for the TORA system. Compared with existing sliding mode control methods for the TORA system, the proposed method here is continuous. Specifically, first, a global diffeomorphism is introduced for the model of the TORA system. Then, an elaborate sliding manifold is constructed, and a continuous sliding mode control scheme is developed to ensure the convergence of the sliding manifold. Furthermore, rigorous theoretical analysis is given. Finally, simulation tests are carried out, and the obtained simulation results demonstrate that the proposed method exhibits superior stabilization control performance and strong robustness.","Title: A three-dimensional measurement method for binocular endoscopes based on deep learning\nYear: 2022\n\nAbstract: In the practice of clinical endoscopy, the precise estimation of the lesion size is quite significant for diagnosis. In this paper, we propose a three-dimensional (3D) measurement method for binocular endoscopes based on deep learning, which can overcome the poor robustness of the traditional binocular matching algorithm in texture-less areas. A simulated binocular image dataset is created from the target 3D data obtained by a 3D scanner and the binocular camera is simulated by 3D rendering software to train a disparity estimation model for 3D measurement. The experimental results demonstrate that, compared with the traditional binocular matching algorithm, the proposed method improves the accuracy and disparity map generation speed by 48.9% and 90.5%, respectively. This can provide more accurate and reliable lesion size and improve the efficiency of endoscopic diagnosis.","Title: A dynamic handover scheme based on bidirectional VLC channel in multi-user attocell networks\nYear: 2022\n\nAbstract: Light fidelity (LiFi) would be a potential optical wireless communications technology for future mixed-spectrum 5G/6G indoor attocell network, which uses light-emitting diodes based as an optical antenna and offers Gbits capacity. For this scenario, a dynamic handover scheme based on bidirectional visible light communications (VLC) channel is proposed, which uses the uplink light sources to characterize terminal’s movement status for the mobility and make the handover decision in contrast to the unidirectional links. The uplink reference signal received power and the movement state are examined, and the created algorithm is executed in the bidirectional VLC test bed. The experimental results show that the proposed method will reduce the terminal’s handover rate by up to 45% and increase the optical network throughput by up to 26% at the experimental data rate compared with the skipping handover scheme for indoor LiFi network.","Title: Reinforcement Learning-Based Visible Light Positioning and Handover Scheme With Stereo-Camera\nYear: 2022\n\nAbstract: Aimed at solving the problems of frequent handover and large overheads for positioning in 6G, this paper proposes a reinforcement learning (RL)-based visible light positioning (VLP) handover scheme by means of a stereo camera system in which a lower handover rate and higher positioning accuracy were achieved simultaneously. Because of the randomness of the distribution location of indoor light sources and obstacles, even if the parameters of light sources and receivers are consistent, users cannot rely on unitary and invariable parameters to determine whether to change the access point (AP) in the process of moving, especially in some special locations. The proposed scheme, which decomposed the user's moving track at different speeds in a VLP system to optimize selecting the AP by using RL at each step, was exhibited and tested. Experimental results show that the proposed scheme achieved millimeter-level positioning accuracy, improved the normalized reward by over 40% and reduced the handover rate by 87% and 78% compared to the immediate handover (IHO) and dwell handover (DHO) methods concurrently.","Title: Bug-Transformer: Automated Program Repair Using Attention-Based Deep Neural Network\nYear: 2022\n\nAbstract: In this paper, we propose a novel transformer-based deep neural network model to learn semantic bug patterns from a corpus of buggy/fixed codes, then generate correct ones automatically. Transformer is a deep learning model relying entirely on attention mechanism to model global dependencies between input and output. Although there are a few endeavors to repair programs by learning neural language models (NLM), many special program properties, such as structure and semantics of an identifier, are not considered in embedding input sequence and designing model effectively, which results in undesired performance. In the proposed Bug-Transformer, we design a novel context abstraction mechanism to better support neural language models. Specifically, it is capable of 1) compressing code information but preserving the key structure and semantics, which provides more thorough information for NLM models, 2) renaming identifiers and literals based on their lexical scopes, structural and semantic information, to reduce code vocabulary size and 3) reserving keywords and selected idioms (domain- or developer-specific vocabularies) for better understanding code structure and semantics. Hence, Bug-Transformer adequately embeds code structural and semantic information into input data and optimize attention-based transformer neural network to well handle code features in order to improve learning tasks for bug repair. We evaluate the performance of the proposed work comprehensively on three datasets (Java code corpora) and generate patches to buggy code using a beam search decoder. The experimental results show that our proposed work outperforms the-state-of-art techniques: Bug-Transformer can successfully predict 54.81%, 34.45%, and 42.40% of the fixed code in these three datasets, respectively, which outperform the baseline models. These success rates steadily increase along with the increase of beam size. Besides, the overall syntactic correctness of all patches remains above 97%, 96%, and 50% on the three benchmarks, respectively, regardless of the beam size.","Title: Experimental Verification of the Modified PSA Algorithm\nYear: 2022\n\nAbstract: Being abundant and non-polluted, solar energy is an increasingly desirable energy source. Growing research is concerned about maximum solar energy acquisition from solar panels, especially in the automatic sun-tracking of the solar panels. This paper presents a modified algorithm based on the \"PSA algorithm\" proposed in the 2001, and presents a new automatic solar tracking system with a two-axis is designed based on the algorithm. The PSA modified algorithm is used to calculate the sun's horizontal azimuth and zenith angle combined with time, longitude, latitude, and other information. This experiment of the prototype mainly composed of a microcontroller, a global positioning system (GPS) module, a digital compass, a tilt sensor, a 555 timer, and gates, optical couples, a H-bridge and two stepper motors. Then a series of experiments are conducted using the proposed prototype in Tianjin City. Measured zenith angle values were collected and recorded based on the PSA modified algorithm and the original PSA algorithm, compared with the actual Zenith Angle of the Sun in Tianjin City. The comparison curves of Zenith Angle show that the measurement accuracy of the modified PSA algorithm is higher than that of the PSA original algorithm."],"string":"[\n \"Title: Fully Secure Attribute-Based Encryption with Non-monotonic Access Structures\\nYear: 2013\\n\\nAbstract: Along with the development of the Internet, the traditional public key encryption system becomes insufficient for many newly emerging applications, such as the cloud services. Then the ABE is proposed to meet the urgent demands. The study on attribute-based encryption mainly concern on two issues: how to improve its expressibility and achieve stronger security. This paper has proposed a attribute-based encryption scheme that has good property in both two points: our scheme allows a user's private key to be expressed in non-monotonic access structures, and we prove its fully security in the standard model. Furthermore, the performance of our scheme is as efficient as the less expressive and selective security ones.\",\n \"Title: Running smart process based on goals\\nYear: 2008\\n\\nAbstract: When Web services are used to coalesce around the distributed applications, one prominent solution to manage and coordinate Web services is the use of process management. Many researches have been done to deal with automatic discovery and composition issues of Web services. However, the problem of how to run a process that is composed of distributed services is seldom considered. In this paper, based on our previous work, the smart process-based application model (SPM), we formalize smart process (SP) using algebra CCS, and discuss the benefits. In particular, we propose goal-based algorithms to run Smart Process.\",\n \"Title: An optimized parallel LSQR algorithm for seismic tomography.\\nYear: 2013\\n\\nAbstract: The LSQR algorithm developed by Paige and Saunders (1982) is considered one of the most efficient and stable methods for solving large, sparse, and ill-posed linear (or linearized) systems. In seismic tomography, the LSQR method has been widely used in solving linearized inversion problems. As the amount of seismic observations increase and tomographic techniques advance, the size of inversion problems can grow accordingly. Currently, a few parallel LSQR solvers are presented or available for solving large problems on supercomputers, but the scalabilities are generally weak because of the significant communication cost among processors. In this paper, we present the details of our optimizations on the LSQR code for, but not limited to, seismic tomographic inversions. The optimizations we have implemented to our LSQR code include: reordering the damping matrix to reduce its band-width for simplifying the communication pattern and reducing the amount of communication during calculations; adopting sparse matrix storage formats for efficiently storing and partitioning matrices; using the MPI I/O functions to parallelize the date reading and result writing processes; providing different data partition strategies for efficiently using computational resources. A large seismic tomographic inversion problem, the full-3D waveform tomography for Southern California, is used to explain the details of our optimizations and examine the performance on Yellowstone supercomputer at the NCAR-Wyoming Supercomputing Center (NWSC). The results showed that the required wall time of our code for the same inversion problem is much less than that of the LSQR solver from the PETSc library (Balay et al., 1997).\",\n \"Title: HAVE: Detecting Atomicity Violations via Integrated Dynamic and Static Analysis\\nYear: 2009\\n\\nAbstract: The reality of multi-core hardware has made concurrent programs pervasive. Unfortunately, writing correct concurrent programs is difficult. Atomicity violation, which is caused by concurrently executing code unexpectedly violating the atomicity of a code segment, is one of the most common concurrency errors. However, atomicity violations are hard to find using traditional testing and debugging techniques. This paper presents a hybrid approach that integrates static and dynamic analyses to attack this problem. We first perform static analysis to obtain summaries of synchronizations and accesses to shared variables. The static summaries are then instantiated with runtime values during dynamic executions to speculatively approximate the behaviors of branches that are not taken. Compared to dynamic analysis, the hybrid approach is able to detect atomicity violations in unexecuted parts of the code. Compared to static analysis, the hybrid approach produces fewer false alarms. We implemented this hybrid analysis in a tool called HAVE that detects atomicity violations in multi-threaded Java programs. Experiments on several benchmarks and real-world applications demonstrate promising results.\",\n \"Title: A model-driven partitioning and auto-tuning integrated framework for sparse matrix-vector multiplication on GPUs\\nYear: 2011\\n\\nAbstract: Sparse Matrix-Vector Multiplication (SpMV) is very common to scientific computing. The Graphics Processing Unit (GPU) has recently emerged as a high-performance computing platform due to its massive processing capability. This paper presents an innovative performance-model driven approach for partitioning sparse matrix into appropriate formats, and auto-tuning configurations of CUDA kernels to improve the performance of SpMV on GPUs. This paper makes the following contributions: (1) Propose an empirical CUDA performance model to predict the execution time of SpMV CUDA kernels. (2) Design and implement a model-driven partitioning framework to predict how to partition the target sparse matrix into one or more partitions and transform each partition into appropriate storage format, which is based on the fact that the different storage formats of sparse matrix can significantly affect the performance of SpMV. (3) Integrate the model-driven partitioning with our previous auto-tuning framework to automatically adjust CUDA-specific parameters to optimize performance on specific GPUs. Compared to the NVIDIA's existing implementations, our approach shows a substantial performance improvement. It has 222%, 197%, and 33% performance improvement on the average for CSR vector kernel, ELL kernel and HYB kernel, respectively.\",\n \"Title: Miniaturized CMOS Imaging Module with Real-time DSP Technology for Endoscope and Laryngoscope Applications\\nYear: 2009\\n\\nAbstract: Miniaturized video camera is a key component in modern medical devices such as endoscopes or other minimally invasive instruments. Here we present a new imaging module which is so small that it can fit through the instrument channels of conventional endoscopes and laryngoscopes. This imaging module includes a 1/18-in. CMOS image sensor and a small integrated lens with field of view of 120°. A Blackfin DSP is used for real-time video processing, including lens distortion compensation, white balance, auto exposure and edge enhancement. The output video signals are displayed on a color LCD monitor. Two white LEDs provide lighting condition. The tip of the imaging module is packaged in a cylinder of diameter 2.5 mm, making many medical applications such as intubation and endoscopy less invasive. It can also be used in machine vision, security and surveillance where small size is important.\",\n \"Title: An Integrated Framework for Checking Concurrency-Related Programming Errors\\nYear: 2009\\n\\nAbstract: Countless challenges to preserving a user’s location privacy exist and have become more important than ever before with the proliferation of handheld devices and the pervasive use of Location-based Services. It is not possible to access Location-based ...\",\n \"Title: Rapid 3D Seismic Source Inversion Using Windows Azure and Amazon EC2\\nYear: 2011\\n\\nAbstract: With its rapid development, cloud computing has been increasingly adopted by scientists for large-scale scientific computation. Compared to the traditional computing platforms such as cluster and supercomputer, cloud computing is more elastic in the support of real-time computation and more powerful in the management of large-scale datasets. This paper presents our experience on designing and implementing seismic source inversion on both cluster (specifically, MPI-based) and cloud computing (specifically, Amazon EC2 and Microsoft Windows Azure). Our experiment shows that applying cloud computing to seismic source inversion is feasible and has its advantages. In addition, we notice that both cluster and Amazon EC2 have obviously better performance than Windows Azure. Cloud computing is suited for real-time processing scientific applications but it (especially Azure) does not work well for tightly-coupled applications.\",\n \"Title: Rapid Processing of Synthetic Seismograms Using Windows Azure Cloud\\nYear: 2010\\n\\nAbstract: Currently, numerically simulated synthetic seismograms are widely used by seismologists for seismological inferences. The generation of these synthetic seismograms requires large amount of computing resources, and the maintenance of these observed seismograms requires massive storage. Traditional high-performance computing platforms is inefficient to handle these applications because rapid computations are needed and large-scale datasets should be maintained. The emerging cloud computing platform provides an efficient substitute. In this paper, we introduce our experience on implementing a computational platform for rapidly computing and delivering synthetic seismograms on Windows Azure. Our experiment shows that cloud computing is an ideal platform for such kind of applications.\",\n \"Title: CRI: symbolic debugger for MCAPI applications\\nYear: 2010\\n\\nAbstract: We present a trace-driven SMT-based symbolic debugging tool for MCAPI (Multicore Association Communication API) applications. MCAPI is a newly proposed standard that provides an API for connectionless and connection-oriented communication in multicore applications. Our tool obtains a trace by executing an instrumented MCAPI. The collected trace is then encoded into an SMT formula such that its satisfiability indicates the existence of a reachable error state such as an assertion failure.\",\n \"Title: Detecting potential deadlocks with static analysis and run-time monitoring\\nYear: 2005\\n\\nAbstract: Concurrent programs are notorious for containing errors that are difficult to reproduce and diagnose. A common kind of concurrency error is deadlock, which occurs when a set of threads is blocked each trying to acquire a lock held by another thread in that set. Static and dynamic (run-time) analysis techniques exist to detect deadlocks. Havelund's GoodLock algorithm detects potential deadlocks at run-time. However, it detects only potential deadlocks involving exactly two threads. This paper presents a generalized version of the GoodLock algorithm that detects potential deadlocks involving any number of threads. Run-time checking may miss errors in unexecuted code. On the positive side, run-time checking generally produces fewer false alarms than static analysis. This paper explores the use of static analysis to automatically reduce the overhead of run-time checking. We extend our type system, Extended Parameterized Atomic Java (EPAJ), which ensures absence of races and atomicity violations, with Boyapati et al.'s deadlock types. We give an algorithm that infers deadlock types for a given program and an algorithm that determines, based on the result of type inference, which run-time checks can safely be omitted. The new type system, called Deadlock-Free EPAJ (DEPAJ), has the added benefit of giving stronger atomicity guarantees than previous atomicity type systems.\",\n \"Title: Hybrid fire detection using hidden Markov model and luminance map\\nYear: 2011\\n\\nAbstract: Recently, fire detection is a hot research topic. Although many detection methods have been proposed, there exist high false alarms because of the interference of fire-colored moving object in the complex environments. In this paper, a hybrid method is proposed. First, we get the set of candidate fire regions. Then these candidate fire regions are analyzed to exclude the fire-colored moving object. Our contributions are using the hidden Markov model (HMM) based on spatio-temporal feature and the variance of luminance map motivated by visual attention, and combining both for fire detection. The wrong detection can be reduced greatly. Experiment results show our proposed method has a good performance and it is robust to be used in complex environment compared with previous algorithms.\",\n \"Title: Automated type-based analysis of data races and atomicity\\nYear: 2005\\n\\nAbstract: Concurrent programs are notorious for containing errors that are difficult to reproduce and diagnose at run-time. This motivated the development of type systems that statically ensure the absence of some common kinds of concurrent programming errors including data races and atomicity violations. A method is atomic if every execution of the concurrent program is equivalent to an execution in which the atomic method is executed without being interleaved with other concurrently executed methods. Atomicity is a common correctness requirement in concurrent programs; atomicity violations may indicate incorrect synchronization. This paper presents Extended Parameterized Atomic Java (EPAJ), a type system for specifying and verifying atomicity in Java programs. EPAJ combines Flanagan and Qadeer's atomicity types [11] with a new and significantly more expressive type system for analyzing data races, called Extended Parameterized Race-Free Java (EPRFJ), allowing a more accurate analysis of atomicity. The paper also presents a type discovery algorithm to automatically obtain EPRFJ types, and a static interprocedural type inference algorithm that, given EPRFJ types, infers atomicity types. These algorithms can be incorporated into testing and debugging tools, benefiting users who know nothing about type systems. We report our experience with a prototype implementation.\",\n \"Title: Optimized run-time race detection and atomicity checking using partial discovered types\\nYear: 2005\\n\\nAbstract: Concurrent programs are notorious for containing errors that are difficult to reproduce and diagnose. Two common kinds of concurrency errors are data races and atomicity violations (informally, atomicity means that executing methods concurrently is equivalent to executing them serially). Several static and dynamic (run-time) analysis techniques exist to detect potential races and atomicity violations. Run-time checking may miss errors in unexecuted code and incurs significant run-time overhead. On the other hand, run-time checking generally produces fewer false alarms than static analysis; this is a significant practical advantage, since diagnosing all of the warnings from static analysis of large codebases may be prohibitively expensive.This paper explores the use of static analysis to significantly decrease the overhead of run-time checking. Our approach is based on a type system for analyzing data races and atomicity. A type discovery algorithm is used to obtain types for as much of the program as possible (complete type inference for this type system is NP-hard, and parts of the program might be untypable). Warnings from the typechecker are used to identify parts of the program from which run-time checking can safely be omitted. The approach is completely automatic, scalable to very large programs, and significantly reduces the overhead of run-time checking for data races and atomicity violations.\",\n \"Title: Message race detection for web services by an SMT-based analysis\\nYear: 2010\\n\\nAbstract: The success of the cloud computing initiative is heavily dependent on realizing trustworthy Web Services. The trustworthiness of a Web Service is judged by four factors: security, privacy, reliability and business integrity. Web Services use message-passing for communication which opens the door for messages races. Messages race with each other when their order of arrival at a destination is not guaranteed and is affected non-deterministically by factors such as network latencies and scheduling variations. Message races are dangerous to Web Services because they can be unforeseen consequences of bugs, causing messages to arrive in an unexpected ordering. In this paper we present a novel approach for improving the reliability of Web Services by detecting message races using SMT-based analysis. We model a BPEL process as a Web Service Modeling Graph (WSMG). A WSMG model is then encoded into a set of SMT constraints. The satisfiability of these constraints means that message races will occur during the actual execution of the Web Service. Hence, we reduce the message race detection problem to constraint solving problem based on satisfiability modulo theories (SMT).\",\n \"Title: Classification Of Seismic Windows Using Artificial Neural Networks\\nYear: 2011\\n\\nAbstract: We examine the plausibility of using an Artificial Neural Network (ANN) and an Importance-Aided Neural Network (IANN) for the refinement of the structural model used to create full-wave tomography images. Specifically, we apply the machine learning techniques to classifying segments of observed data wave seismograms and synthetic data wave seismograms as either usable for iteratively refining the structural model or not usable for refinement. Segments of observed and synthetic seismograms are considered usable if they are not too different, a heuristic observation made by a human expert, which is considered a match. The use of the ANN and the IANN for classification of the data wave segments removes the human computational cost of the classification process and removes the need for an expert to oversee all such classifications. Our experiments on the seismic data for Southern California have shown this technique to he promising for both classification accuracy and the reduction of the time required to compute the classification of observed data wave segment and synthetic data wave segment matches.\",\n \"Title: SAM: self-adaptive dynamic analysis for multithreaded programs\\nYear: 2011\\n\\nAbstract: Many dynamic analysis techniques have been proposed to detect incorrect program behaviors resulted from faulty code. However, the huge overhead incurred by such dynamic analysis prevents thorough testing of large-scale software systems. In this paper, we propose a novel framework using compile-time and run-time optimizations on instrumentation and monitoring that aim to significantly reduce the overhead of dynamic analysis on multithreaded programs. We implemented a tool called SAM (Self-Adaptive Monitoring) that can selectively turn off excessive monitoring on repeated code region invocations if the current program context has been determined to be redundant, which may assist many existing dynamic detection tools to improve their performance. Specifically, we approximate the program context for a code region invocation as a set of variables, which include path-critical variables and shared variables accessed in that region. The path-critical variables are inferred using a use-definition dataflow analysis, and the shared variables are identified using a hybrid thread-based escape analysis. We have implemented the tool in Java and evaluated it on a set of real-world programs. Our experimental results show that it can significantly reduce the runtime overhead of the baseline atomicity violation and data race analyses by an average of 50% and 20%, respectively, while roughly keeping the accuracy of the underlying runtime detection tools.\",\n \"Title: A Performance Modeling And Optimization Analysis Tool For Sparse Matrix-Vector Multiplication On Gpus\\nYear: 2014\\n\\nAbstract: This paper presents a performance modeling and optimization analysis tool to predict and optimize the performance of sparse matrix-vector multiplication (SpMV) on GPUs. We make the following contributions: 1) We present an integrated analytical and profile-based performance modeling to accurately predict the kernel execution times of CSR, ELL, COO, and HYB SpMV kernels. Our proposed approach is general, and neither limited by GPU programming languages nor restricted to specific GPU architectures. In this paper, we use CUDA-based SpMV kernels and NVIDIA Tesla C2050 for our performance modeling and experiments. According to our experiments, for 77 out of 82 test cases, the performance differences between the predicted and measured execution times are less than 9 percent; for the rest five test cases, the differences are between 9 and 10 percent. For CSR, ELL, COO, and HYB SpMV CUDA kernels, the average differences are 6.3, 4.4, 2.2, and 4.7 percent, respectively. 2) Based on the performance modeling, we design a dynamic-programming based SpMV optimal solution auto-selection algorithm to automatically report an optimal solution (i.e., optimal storage strategy, storage format(s), and execution time) for a target sparse matrix. In our experiments, the average performance improvements of the optimal solutions are 41.1, 49.8, and 37.9 percent, compared to NVIDIA's CSR, COO, and HYB CUDA kernels, respectively.\",\n \"Title: P&P: A Combined Push-Pull Model for Resource Monitoring in Cloud Computing Environment\\nYear: 2010\\n\\nAbstract: Cloud computing paradigm contains many shared resources, such as infrastructures, data storage, various platforms and software. Resource monitoring involves collecting information of system resources to facilitate decision making by other components in Cloud environment. It is the foundation of many major Cloud computing operations. In this paper, we extend the prevailing monitoring methods in Grid computing, namely Pull model and Push model, to the paradigm of Cloud computing. In Grid computing, we find that in certain conditions, Push model has high consistency but low efficiency, while Pull model has low consistency but high efficiency. Based on complementary properties of the two models, we propose a user-oriented resource monitoring model named Push&Pull (P&P) for Cloud computing, which employs both the above two models, and switches the two models intelligently according to users' requirements and monitored resources' status. The experimental result shows that the P&P model decreases updating costs and satisfies various users' requirements of consistency between monitoring components and monitored resources compared to the original models.\",\n \"Title: Accelerating the discontinuous Galerkin method for seismic wave propagation simulations using the graphic processing unit (GPU)-single-GPU implementation\\nYear: 2013\\n\\nAbstract: We have successfully ported an arbitrary high-order discontinuous Galerkin (ADER-DG) method for solving the three-dimensional elastic seismic wave equation on unstructured tetrahedral meshes to an Nvidia Tesla C2075 GPU using the Nvidia CUDA programming model. On average our implementation obtained a speedup factor of about 24.3 for the single-precision version of our GPU code and a speedup factor of about 12.8 for the double-precision version of our GPU code when compared with the double precision serial CPU code running on one Intel Xeon W5880 core. When compared with the parallel CPU code running on two, four and eight cores, the speedup factor of our single-precision GPU code is around 12.9, 6.8 and 3.6, respectively. In this article, we give a brief summary of the ADER-DG method, a short introduction to the CUDA programming model and a description of our CUDA implementation and optimization of the ADER-DG method on the GPU. To our knowledge, this is the first study that explores the potential of accelerating the ADER-DG method for seismic wave-propagation simulations using a GPU.\",\n \"Title: Run-Time Analysis for Atomicity\\nYear: 2003\\n\\nAbstract: Writing and debugging concurrent (shared-variable) programs is notoriously difficult. This motivated the development of numerous static analysis and run-time analysis techniques designed to (help) ensure that concurrent programs satisfy common correctness requirements for concurrent programs, such as absence of race conditions and absence of deadlocks. This paper focuses on another common correctness requirement for concurrent programs, namely, atomicity, which requires that any set of concurrent invocations of designated procedures is equivalent to performing those invocations serially in some order. Run-time analysis algorithms for detecting violations of atomicity are presented. The algorithms vary in cost and precision.\",\n \"Title: HEAT: a combined approach for thread escape analysis.\\nYear: 2011\\n\\nAbstract: Thread escape analysis can determine whether and when a variable becomes shared by multiple threads, which is a foundation for many other program analysis and software testing techniques. Most existing escape analysis tools are either purely dynamic or static analyses. Static analysis, which considers all possible behaviors of a program, may produce false positives; whereas dynamic approaches miss the information from unexecuted code sections of a program. This paper presents a hybrid approach that integrates static and dynamic analyses to address this problem. We first perform static analysis to obtain succinct summaries of accesses to all variables and interprocedural information. Dynamic analysis is then used to confirm variable sharing; for unexecuted code, we determine the sharing of variables by performing an interprocedural synthesis based on the runtime information and static summaries. Compared to dynamic analysis, the hybrid approach is able to determine the escape property of variables in unexecuted code. Compared to static analysis, the hybrid approach produces fewer false alarms. We implemented this hybrid escape analysis in Java. Our experiments on several benchmarks and real-world applications show that the hybrid approach improves the accuracy of escape analysis compared to existing approaches and significantly reduces the performance overhead of a subsequent program analysis.\",\n \"Title: A Dataflow-Oriented Atomicity and Provenance System for Pipelined Scientific Workflows\\nYear: 2007\\n\\nAbstract: Scientific workflows have gained great momentum in recent years due to their critical roles in e-Science and cyberinfrastructure applications. However, some tasks of a scientific workflow might fail during execution. A domain scientist might require a region of a scientific workflow to be \\\"atomic\\\". Data provenance, which determines the source data that are used to produce a data item, is also essential to scientific workflows. In this paper, we propose: (i) an architecture for scientific workflow management systems that supports both provenance and atomicity; (ii) a dataflow-oriented atomicity model that supports the notions of commit and abort; and (iii) a dataflow-oriented provenance model that, in addition to supporting existing provenance graphs and queries, also supports queries related to atomicity and failure.\",\n \"Title: Accurate and efficient runtime detection of atomicity errors in concurrent programs\\nYear: 2006\\n\\nAbstract: Atomicity is an important correctness condition for concurrent systems. Informally, atomicity is the property that every concurrent execution of a set of transactions is equivalent to some serial execution of the same transactions. In multi-threaded programs, executions of procedures (or methods) can be regarded as transactions. Correctness in the presence of concurrency often requires atomicity of these transactions. Tools that automatically detect atomicity violations can uncover subtle errors that are hard to find with traditional debugging and testing techniques.This paper presents new algorithms for runtime (dynamic) detection of violations of conflict-atomicity and view-atomicity, which are analogous to conflict-serializability and view-serializability in database systems. In these algorithms, the recorded events are formed into a graph with edges representing the synchronization within each transaction and possible interactions between transactions. We give conditions on the graph that imply conflict-atomicity and view-atomicity. Experiments show that these new algorithms are more efficient in most experiments and are more accurate than previous algorithms with comparable asymptotic complexity.\",\n \"Title: MRGIS: A MapReduce-Enabled High Performance Workflow System for GIS\\nYear: 2008\\n\\nAbstract: The growth of data used by data-intensive computations, e.g. geographical information systems (GIS), has far outpaced the growth of the power of a single processor. The increasing demand of data-intensive applications calls for distributed computing. In this paper, we propose a high performance workflow system MRGIS, a parallel and distributed computing platform based on MapReduce clusters, to execute GIS applications efficiently. MRGIS consists of a design interface, a task scheduler, and a runtime support system. The design interface has two options: a GUI-based workflow designer and an API-based library for programming in Python. Given a GIS workflow, the scheduler analyzes data dependencies among tasks, then dispatches them to MapReduce clusters based on the current status of the system. Our experiment demonstrates that MRGIS can significantly improve the performance of GIS workflow execution.\",\n \"Title: Research on patterns of cancer markers based on cross section imaging of serum proteomic data\\nYear: 2007\\n\\nAbstract: New proteomic technologies have brought the hope of discovering novel early cancer-specific biomarkers in complex biological samples. Novel mass spectrometry (MS) based technologies in particular, such as surface-enhanced laser desorption/ionisation time of flight (SELDI-TOF-MS), have shown promising results in recent years. To find new potential biomarkers and establish the patterns for detection of cancers, we proposed a novel method to analysis SELDI-TOF-MS using binary cross section imaging and energy curve technology. The proposed method with advantage of visualization is to mining local information adequately so as to discriminate cancer samples from non-cancer ones. Applying the procedure to MS data of proteomic analysis of serum from ovarian cancer patients and serum from cancer-free individuals in the Food and Drug Administration/National Cancer Institute Clinical Proteomics Database, we find that there are outputs of the cancerous when the threshold is above 90 and M/Z is in the range 9362.3296-9747.2723, while outputs of the non-cancerous will appear when the threshold is 60 80 and M/Z is 243.4940-247.8824.\",\n \"Title: HEAT: An Integrated Static and Dynamic Approach for Thread Escape Analysis\\nYear: 2009\\n\\nAbstract: Escape analysis can determine whether and when a variable becomes shared for multiple threads, which is a foundation for many other program analyses. Most existing escape analysis tools are either purely dynamic or static analysis. Static analysis usually considers all possible behaviors of a program, however, may produce false positives; whereas dynamic approaches can not analyze unobserved behaviors of a program. This paper presents a hybrid approach that integrates static and dynamic analyses to address this problem. We first perform static analysis to obtain summaries of accesses to potential escaped variables. When the program runs, dynamic analysis is used to confirm variable sharing; for unexecuted code, we determine the sharing of variables in it by performing an interprocedural static analysis based on the runtime information. Compared to dynamic analysis, the hybrid approach is able to determine the escape property of variables in unexecuted code. Compared to static analysis, the hybrid approach produces fewer false alarms. We implemented this hybrid escape analysis in Java. Our experimental evaluation on several benchmarks and real-world applications shows that it has improved accuracy compared to existing approaches and can also boost the performance of subsequent program analyses significantly.\",\n \"Title: Symbolic Analysis of Concurrency Errors in OpenMP Programs\\nYear: 2013\\n\\nAbstract: In this paper we present the OpenMP Analysis Toolkit (OAT), which uses Satisfiability Modulo Theories (SMT) solver based symbolic analysis to detect data races and deadlocks in OpenMP codes. Our approach approximately simulates real executions of an OpenMP program through schedule permutation. We conducted experiments on real-world OpenMP benchmarks and student homework assignments by comparing our OAT tool with two commercial dynamic analysis tools: Intel Thread Checker and Sun Thread Analyzer, and one commercial static analysis tool: Viva64 PVS Studio. The experiments show that our symbolic analysis approach is more accurate than static analysis and more efficient and scalable than dynamic analysis tools with less false positives and negatives.\",\n \"Title: Static analysis of atomicity for programs with non-blocking synchronization\\nYear: 2005\\n\\nAbstract: In concurrent programming, non-blocking synchronization is very efficient but difficult to design correctly. This paper presents a static analysis to show that code blocks are atomic, i.e., that every execution of the program is equivalent to one in which those code blocks execute without interruption by other threads. Our analysis determines commutativity of operations based primarily on how synchronization primitives (including locks, load-linked, store-conditional, and compare-and-swap) are used. A reduction theorem states that certain patterns of commutativity imply atomicity. Atomicity is itself an important correctness requirement for many concurrent programs. Furthermore, an atomic code block can be treated as a single transition during subsequent analysis of the program; this can greatly improve the efficiency of the subsequent analysis. We demonstrate the effectiveness of our approach on several concurrent non-blocking programs.\",\n \"Title: An MPI-CUDA Implementation and Optimization for Parallel Sparse Equations and Least Squares (LSQR).\\nYear: 2012\\n\\nAbstract: LSQR (Sparse Equations and Least Squares) is a widely used Krylov subspace method to solve large-scale linear systems in seismic tomography. This paper presents a parallel MPI-CUDA implementation for LSQR solver. On CUDA level, our contributions include: (1) utilize CUBLAS and CUSPARSE to compute major steps in LSQR; (2) optimize memory copy between host memory and device memory; (3) develop a CUDA kernel to perform transpose SpMV without transposing the matrix in memory or preserving additional copy. On MPI level, our contributions include: (1) decompose both matrix and vector to increase parallelism; (2) design a static load balancing strategy. In our experiment, the single GPU code achieves up to 17.6x speedup with 15.7 GFlops in single precision and 15.2x speedup with 12.0 GFlops in double precision compared with the original serial CPU code. The MPI-GPU code achieves up to 3.7x speedup with 268 GFlops in single precision and 3.8x speedup with 223 GFlops in double precision on 135 MPI tasks compared with the corresponding MPI-CPU code. The MPI-GPU code scales on both strong and weak scaling tests. In addition, our parallel implementations have better performance than the LSQR subroutine in PETSc library.\",\n \"Title: A Scalable Parallel LSQR Algorithm for Solving Large-Scale Linear System for Tomographic Problems: A Case Study in Seismic Tomography.\\nYear: 2013\\n\\nAbstract: Least Squares with QR-factorization (LSQR) method is a widely used Krylov subspace algorithm to solve sparse rectangu- lar linear systems for tomographic problems. Traditional parallel implementations of LSQR have the potential, depending on the non-zero structure of the matrix, to have significant communication cost. The communication cost can dramatically limit the scalability of the algorithm at large core counts. We describe a scalable parallel LSQR algorithm that utilizes the particular non-zero structure of matrices that occurs in tomographic problems. In particular, we specially treat the kernel component of the matrix, which is relatively dense with a random structure, and the damping component, which is very sparse and highly structured separately. The resulting algorithm has a scalable communication volume with a bounded number of communica- tion neighbors regardless of core count. We present scaling studies from real seismic tomography datasets that illustrate good scalability up to O(10, 000) cores on a Cray XT cluster.\",\n \"Title: An OpenMP Analyzer for Detecting Concurrency Errors\\nYear: 2012\\n\\nAbstract: As one of the popularparallel programming interfaces, OpenMP has been widely used in many scientific applications in order to facilitate shared-memory parallelism. With the increasing popularity of multi-core machines, more and more sequential programs are being parallelized using OpenMP. However, it is not easy for programmers to write parallel programs correctly. Concurrency errors, such as data races and deadlocks. This paper presents a novel technique to detect data races and deadlocks using hybrid program analysis. Previous work [2] has shown the symbolic execution on GPU program, our tool exploits SMT solver to detect errors in OpenMP program.\",\n \"Title: SD-GIS-based temporal-spatial simulation of water quality in sudden water pollution accidents\\nYear: 2011\\n\\nAbstract: System dynamics (SD) is well suited for studying dynamic nonlinear complex systems. In this paper, SD is applied to a rapid-onset water pollution accident using a 1-D water quality model and a conceptual GIS-SD framework is constructed to simulate the temporal-spatial changes of pollutant concentration. Based on the component GIS and the SD model, a prototype system of water quality simulation in water pollution accidents is developed. The data collected on the spot in the Songhua River water pollution accident in November 2005 were used for model parameter calibration and model validation. The results showed that: (1) the constructed model could simulate the changes of nitrobenzene concentration with time in the Songhua River water pollution accident, especially during the peak concentration and at the arrival time of peak concentration, and that the simulated values and the on-the-spot monitored values corresponded with each other well; (2) the scenario simulation could be made by adjusting parameters u (longitudinal current velocity), E (longitudinal diffusion coefficient), and k (decay rate coefficient). Such a model can provide decision makers with quantitative information to optimize related emergency response measures.\",\n \"Title: CAP3: A Cloud Auto-Provisioning Framework for Parallel Processing Using On-Demand and Spot Instances\\nYear: 2013\\n\\nAbstract: Cloud computing has drawn increasing attention from the scientific computing community due to its ease of use, elasticity, and relatively low cost. Because a high-performance computing (HPC) application is usually resource demanding, without careful planning, it can incur a high monetary expense even in Cloud. We design a tool called CAP3 (Cloud Auto-Provisioning framework for Parallel Processing) to help a user minimize the expense of running an HPC application in Cloud, while meeting the user-specified job deadline. Given an HPC application, CAP3 automatically profiles the application, builds a model to predict its performance, and infers a proper cluster size that can finish the job within its deadline while minimizing the total cost. To further reduce the cost, CAP3 intelligently chooses the Cloud's reliable on-demand instances or low-cost spot instances, depending on whether the remaining time is tight in meeting the application's deadline. Experiments on Amazon EC2 show that the execution strategy given by CAP3 is cost-effective, by choosing a proper cluster size and a proper instance type (on-demand or spot).\",\n \"Title: Atomicity and provenance support for pipelined scientific workflows\\nYear: 2009\\n\\nAbstract: Today many significant scientific discoveries are achieved through complex and distributed scientific computations that are structured and represented as scientific workflows. Although atomicity is a well studied topic in transaction processing and business workflows, such an important capability needs to be revisited in a scientific workflow environment. Firstly, the semantics of atomicity needs to be defined in a dataflow-oriented scientific workflow model, particularly for pipelined execution of hierarchical scientific workflows. Secondly, in a scientific workflow environment, atomic regions are specified or inferred dynamically as needed and are committed implicitly, which are in contrast to a priori well-defined transaction boundaries and explicit commits in transaction processing and business workflows. Finally, although atomicity and provenance are related to each other, their interactions and relationships have never been explored in the literature. In this paper, we propose: (i) an architecture for scientific workflow management systems that supports both provenance and atomicity; (ii) a dataflow-oriented atomicity model that supports the notions of commit and abort; and (iii) a dataflow-oriented provenance model that supports querying and visualizing provenance.\",\n \"Title: A Cloud Computing Platform for Large-Scale Forensic Computing\\nYear: 2009\\n\\nAbstract: The timely processing of massive digital forensic collections demands the use of large-scale distributed computing resources and the flexibility to customize the processing performed on the collections. This paper describes MPI Map Reduce (MMR), an open implementation of the Map Reduce processing model that outperforms traditional forensic computing techniques. MMR provides linear scaling for CPU-intensive processing and super-linear scaling for indexing-related workloads.\",\n \"Title: The performance of replaceable linear polyacrylamide(PLA) gel electrophoresis of DNA analyzer\\nYear: 2011\\n\\nAbstract: We report the replaceable Linear polyacrylamide(LPA) gel was synthesized in house; the inner surface of capillary was coated with the same sieving medium (LPA). The DNA analyzer which was designed by authors group to detect the samples of capillary electrophoresis (CE) with laser induced fluorescence (LIF); The data collected with indirect methods establishes confidence in the electroosmotic mobility values obtained. Constant electroosmotic mobilities of 2.5×10\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">-8</sup>\\nm\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sup>\\nV\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">-1</sup>\\ns\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">-1</sup>\\n was determined by tests. The bubbles in the LPA gel capillary electrophoresis were observed and recorded. It was discovered the bubbles can be reduced and affect CE little. A good linear CE current increase with applied field strength indicated the negligible Joule heating effects were present. This work will help to further optimize and improve high performance DNA separation in microfluidic applications.\",\n \"Title: Virbase: A Resource For Virus-Host Ncrna-Associated Interactions\\nYear: 2015\\n\\nAbstract: Increasing evidence reveals that diverse non-coding RNAs (ncRNAs) play critically important roles in viral infection. Viruses can use diverse ncRNAs to manipulate both cellular and viral gene expression to establish a host environment conducive to the completion of the viral life cycle. Many host cellular ncRNAs can also directly or indirectly influence viral replication and even target virus genomes. ViRBase ( ext-link-type=\\\"uri\\\" xlink:href=\\\"http://www.rna-society.org/virbase\\\" xlink:type=\\\"simple\\\">http://www.rna-society.org/virbase) aims to provide the scientific community with a resource for efficient browsing and visualization of virus-host ncRNA-associated interactions and interaction networks in viral infection. The current version of ViRBase documents more than 12 000 viral and cellular ncRNA-associated virus-virus, virus-host, host-virus and host-host interactions involving more than 460 non-redundant ncRNAs and 4400 protein-coding genes from between more than 60 viruses and 20 hosts. Users can query, browse and manipulate these virus-host ncRNA-associated interactions. ViRBase will be of help in uncovering the generic organizing principles of cellular virus-host ncRNA-associated interaction networks in viral infection.\",\n \"Title: SMARTH: Enabling Multi-pipeline Data Transfer in HDFS\\nYear: 2014\\n\\nAbstract: Hadoop is a popular open-source implementation of the MapReduce programming model to handle large data sets, and HDFS is one of Hadoop's most commonly used distributed file systems. Surprisingly, we found that HDFS is inefficient when handling upload of data files from client local file system, especially when the storage cluster is configured to use replicas. The root cause is HDFS's synchronous pipeline design. In this paper, we introduce an improved HDFS design called SMARTH. It utilizes asynchronous multi-pipeline data transfers instead of a single pipeline stop-and-wait mechanism. SMARTH records the actual transfer speed of data blocks and sends this information to the namenode along with periodic heartbeat messages. The namenode sorts datanodes according to their past performance and tracks this information continuously. When a client initiates an upload request, the namenode will send it a list of \\\\\\\"high performance\\\\\\\" datanodes that it thinks will yield the highest throughput for the client. By choosing higher performance datanodes relative to each client and by taking advantage of the multi-pipeline design, our experiments show that SMARTH significantly improves the performance of data write operations compared to HDFS. Specifically, SMARTH is able to improve the throughput of data transfer by 27-245% in a heterogeneous virtual cluster on Amazon EC2.\",\n \"Title: Enterprise Relationship Network: Build Foundation for Social Business\\nYear: 2014\\n\\nAbstract: Social business moves beyond linear, process-driven organizations to create new, dynamic, networked businesses that focus on customer value. Enterprise relationship network (ERN) can be used to support social business by maximizing current and future opportunities and facilitate network-enabled processes, which can lead to value co-creation. In this paper we give the specification of ERN, which links the main entities in social business together, such as enterprises, business activities, employees and products. ERN provides a set of methods for analyzing the structure of whole entities as well as a group of algorithms for exploring the patterns in these structures. We present the technique architecture of ERN and describe how the ERN supports social business. We can get a lot of valuable information from ERN, which can be used in enterprise management, employee collaborations and networked businesses. At last, through a case study on the platform of SDCMSP, we evaluate how our proposed approach supports social business and show some relationship visualization results.\",\n \"Title: Runtime analysis of atomicity for multithreaded programs\\nYear: 2006\\n\\nAbstract: Abstract—Atomicity is a correctness condition for concurrent systems. Informally, atomicity is the property that every concurrent execution of a set of transactions is equivalent to some serial execution of the same transactions. In multithreaded programs, executions,of procedures,(or methods) can be regarded,as transactions. Correctness in the presence,of concurrency,typically requires atomicity of these transactions. Tools that automatically,detect atomicity violations can uncover,subtle errors that are hard to find with traditional debugging,and testing techniques. This paper describes,two algorithms,for runtime detection of atomicity violations and compares,their cost and effectiveness. The reduction-based algorithm checks atomicity based on commutativity,properties of events in a trace; the block-based algorithm efficiently represents the relevant information about a trace as a set of blocks (i.e., pairs of events plus associated,synchronizations) and checks,atomicity by comparing,each block with other blocks. To improve,the efficiency and accuracy of both algorithms, we incorporate a multilockset algorithm for checking data races, dynamic escape analysis, and happen- before analysis. Experiments,show,that both algorithms are effective in finding atomicity violations. The block-based algorithm is more accurate,but more,expensive,than the reduction-based,algorithm. Index Terms—Concurrent programming, testing and debugging, Java, data race, atomicity. 1I NTRODUCTION\",\n \"Title: Data Replication in Data Intensive Scientific Applications with Performance Guarantee\\nYear: 2011\\n\\nAbstract: Data replication has been well adopted in data intensive scientific applications to reduce data file transfer time and bandwidth consumption. However, the problem of data replication in Data Grids, an enabling technology for data intensive applications, has proven to be NP-hard and even non approximable, making this problem difficult to solve. Meanwhile, most of the previous research in this field is either theoretical investigation without practical consideration, or heuristics-based with little or no theoretical performance guarantee. In this paper, we propose a data replication algorithm that not only has a provable theoretical performance guarantee, but also can be implemented in a distributed and practical manner. Specifically, we design a polynomial time centralized replication algorithm that reduces the total data file access delay by at least half of that reduced by the optimal replication solution. Based on this centralized algorithm, we also design a distributed caching algorithm, which can be easily adopted in a distributed environment such as Data Grids. Extensive simulations are performed to validate the efficiency of our proposed algorithms. Using our own simulator, we show that our centralized replication algorithm performs comparably to the optimal algorithm and other intuitive heuristics under different network parameters. Using GridSim, a popular distributed Grid simulator, we demonstrate that the distributed caching technique significantly outperforms an existing popular file caching technique in Data Grids, and it is more scalable and adaptive to the dynamic change of file access patterns in Data Grids.\",\n \"Title: A new thermal protection approach for permanent magnet synchronous motor\\nYear: 2013\\n\\nAbstract: This paper presents a new thermal protection approach for permanent magnet synchronous motor. Usually the thermal protection model is built based on two parameters which are thermal resistance and thermal capacitance of motor. But the stator core loss is increased significantly when the motor frequency and the motor winding temperature are increased. If the motor runs at high speed, the eddy current loss, the hysteresis loss and the harmonic current loss dominate the stator core loss. If only the thermal resistance and thermal capacitance are used for the thermal protection without considering the motor frequency, the protection model cannot response the temperature rising when the motor runs at high speed, so the motor could not be protected effectively. In this paper, the motor frequency is included in the new thermal protection approach, and the whole working speed range will be protected, and the motor lifetime will be increased.\",\n \"Title: Faqs: Fast Web Service Composition Algorithm Based On Qos-Aware Sampling\\nYear: 2016\\n\\nAbstract: Web Service Composition (WSC) has been well recognized as a convenient and flexible way of service sharing and integration in service-oriented application fields. WSC aims at selecting and composing a set of initial services with respect to the Quality of Service (QoS) values of their attributes (e.g., price), in order to complete a complex task and meet user requirements. A major research challenge of the QoS-aware WSC problem is to select a proper set of services to maximize the QoS of the composite service meeting several QoS constraints upon various attributes, e.g. total price or runtime. In this article, a fast algorithm based on QoS-aware sampling (FAQS) is proposed, which can efficiently find the near-optimal composition result from sampled services. FAQS consists of five steps as follows. 1) QoS normalization is performed to unify different metrics for QoS attributes. 2) The normalized services are sampled and categorized by guaranteeing similar number of services in each class. 3) The frequencies of the sampled services are calculated to guarantee the composed services are the most frequent ones. This process ensures that the sampled services cover as many as possible initial services. 4) The sampled services are composed by solving a linear programming problem. 5) The initial composition results are further optimized by solving a modified multi-choice multi-dimensional knapsack problem (MMKP). Experimental results indicate that FAQS is much faster than existing algorithms and could obtain stable near-optimal result.\",\n \"Title: Accurate cross‒architecture performance modeling for sparse matrix‒vector multiplication (SpMV) on GPUs\\nYear: 2015\\n\\nAbstract: This paper presents an integrated analytical and profilebased crossarchitecture performance modeling tool to specifically provide interarchitecture performance prediction for Sparse MatrixVector Multiplication (SpMV) on NVIDIA GPU architectures. To design and construct the tool, we investigate the interarchitecture relative performance for multiple SpMV kernels. For a sparse matrix, based on its SpMV kernel performance measured on a reference architecture, our crossarchitecture performance modeling tool can accurately predict its SpMV kernel performance on a target architecture. The prediction results can effectively assist researchers in making choice of an appropriate architecture that best fits their needs from a wide range of available computing architectures. We evaluate our tool with 14 widelyused sparse matrices on four GPU architectures: NVIDIA Tesla C2050, Tesla M2090, Tesla K20m, and GeForce GTX 295. In our experiments, Tesla C2050 works as the reference architecture, the other three are used as the target architectures. For Tesla M2090, the average performance differences between the predicted and measured SpMV kernel execution times for CSR, ELL, COO, and HYB SpMV kernels are 3.1%, 5.1%, 1.6%, and 5.6%, respectively. For Tesla K20m, they are 6.9%, 5.9%, 4.0%, and 6.6% on the average, respectively. For GeForce GTX 295, they are 5.9%, 5.8%, 3.8%, and 5.9% on the average, respectively. Copyright (c) 2014 John Wiley & Sons, Ltd.\",\n \"Title: HBTM: A Heartbeat-based Behavior Detection Mechanism for POSIX Threads and OpenMP Applications.\\nYear: 2015\\n\\nAbstract: Extreme-scale computing involves hundreds of millions of threads with multi-level parallelism running on large-scale hierarchical and heterogeneous hardware. In POSIX threads and OpenMP applications, some key behaviors occurring in runtime such as thread failure, busy waiting, and exit need to be accurately and timely detected. However, for the most of these applications, there are lack of unified and efficient detection mechanisms to do this. In this paper, a heartbeat-based behavior detection mechanism for POSIX threads (Pthreads) and OpenMP applications (HBTM) is proposed. In the design, two types of implementations are conducted, centralized and decentralized respectively. In both implementations, unified API has been designed to guarantee the generality of the mechanism. Meanwhile, a ring-based detection algorithm is designed to ease the burden of the centra thread at runtime. To evaluate the mechanism, the NAS Parallel Benchmarks (NPB) are used to test the performance of the HBTM. The experimental results show that the HBTM supports detection of behaviors of POSIX threads and OpenMP applications while acquiring a short latency and near 1% overhead.\",\n \"Title: An Intelligent QoS Identification for Untrustworthy Web Services via Two-Phase Neural Networks\\nYear: 2016\\n\\nAbstract: QoS identification for untrustworthy Web services is critical in QoS management in the service computing since the performance of untrustworthy Web services may result in QoS downgrade. The key issue is to intelligently learn the characteristics of trustworthy Web services from different QoS levels, then to identify the untrustworthy ones according to the characteristics of QoS metrics. As one of the intelligent identification approaches, deep neural network has emerged as a powerful technique in recent years. In this paper, we propose a novel two-phase neural network model to identify the untrustworthy Web services. In the first phase, Web services are collected from the published QoS dataset. Then, we design a feedforward neural network model to build the classifier for Web services with different QoS levels. In the second phase, we employ a probabilistic neural network (PNN) model to identify the untrustworthy Web services from each classification. The experimental results show the proposed approach has 90.5% identification ratio far higher than other competing approaches.\",\n \"Title: Cloud Computing Research Analysis Using Bibliometric Method\\nYear: 2015\\n\\nAbstract: Cloud computing has been a mainstream solution for the processing and storage of mass data, as well as an exciting area for research. As a novel business model, cloud computing has dramatically changed the provision of services and IT capacity by means of the advanced techniques. In recent years, with the increasing research interests and rapid growth of publications, some review papers provide detailed analysis on cloud computing area. In this paper, a bibliometric-based approach is presented and implemented to quantitatively review the progress in global cloud computing research with the related literature during 2007-2013 from the databases of Science Citation Index Expanded (SCI-E), Conference Proceedings Citation Index-Science (CPCI-S), and IEEEXplore. Our work is motivated by the purpose of tracing global advancement in terms of research content, geographic distribution and issue time of the related publications, rather than a specific technological area in cloud computing research. By investigating the characteristics of publications such as keywords, output, geographic distribution and affiliation, we draw some valuable conclusions to guide the further research. The experimental results show that the top 5 active research points of cloud computing concentrate on virtualization, security, mobile cloud, distributed computing, and scheduling. From the location-time aspect, China, USA, and India have published most of the papers, dominate cloud computing research and keep a high level on the international research cooperation. And there is a great increase in publication outputs especially in China and USA. Meanwhile, the analysis results demonstrate the top 3 high-cited research institutes of the University of Melbourne, University of California. Berkeley and University of Vienna in cloud computing research. The mobile cloud will be a future research hotspot and promising application field.\",\n \"Title: Detecting Thread-Safety Violations in Hybrid OpenMP/MPI Programs\\nYear: 2015\\n\\nAbstract: We propose an approach by integrating static and dynamic program analyses to detect threadsafety violations in hybrid MPI/OpenMP programs. We innovatively transform the thread-safety violation problems to race conditions problems. In our approach, the static analysis identifies a list of MPI calls related to thread-safety violations, then replaces them with our own MPI wrappers, which involve accesses to some specific shared variables. The static analysis avoids instrumenting unrelated code, which significantly reduces runtime overhead. In the dynamic analysis, both happen-before and lockset-based race detection algorithms are used to detect races on these aforementioned shared variables. By detecting races, we can identify thread-safety violations according to their specifications. Our experimental evaluation over real-world applications shows that our approach is both accurate and efficient.\",\n \"Title: Dart: A Geographic Information System on Hadoop\\nYear: 2015\\n\\nAbstract: In the field of big data research, analytics on spatio-temporal data from social media is one of the fastest growing areas and poses a major challenge on research and application. An efficient and flexible computing and storage platform is needed for users to analyze spatio-temporal patterns in huge amount of social media data. This paper introduces a scalable and distributed geographic information system, called Dart, based on Hadoop and HBase. Dart provides a hybrid table schema to store spatial data in HBase so that the Reduce process can be omitted for operations like calculating the mean center and the median center. It employs reasonable pre-splitting and hash techniques to avoid data imbalance and hot region problems. It also supports massive spatial data analysis like K-Nearest Neighbors (KNN) and Geometric Median Distribution. In our experiments, we evaluate the performance of Dart by processing 160 GB Twitter data on an Amazon EC2 cluster. The experimental results show that Dart is very scalable and efficient.\",\n \"Title: A Resilient Framework for Fault Handling in Web Service Oriented Systems\\nYear: 2015\\n\\nAbstract: Resilience is an important factor in designing web service oriented systems due to frequent failures arising in runtime. These failures derive from the stochastic and uncertainty nature of a composite web service. Service providers need to rapidly address issue when a fault occurs in system running. But it is not easy to locate and fix the faults only using the log generated by the system. In this paper, we propose a resilient framework to automatically generate a fault handling strategy for each failed service to improve the efficiency of fault handling. In the framework, we design and implement three components including exception analyzer, decision maker, and strategy selector. First, The exception analyzer builds a record, derived from the system log generated by an application, for each failed service. Next, the decision maker adopts a k-means clustering approach to construct a decision including the fault handling to each failed service in a scope. Then, the strategy selector uses an integer program solver to generate the solution to strategy selection problem that is boiled down to the optimization problem. The experiment shows that the framework can improve resilience of Web service-oriented systems under acceptable overheads, and meanwhile the accuracy of fault handling strategy is over 95%.\",\n \"Title: A Novel Concurrent Generalized Deadlock Detection Algorithm in Distributed Systems.\\nYear: 2015\\n\\nAbstract: Detecting deadlocks has been considered an important problem in distributed systems. Many approaches are proposed to handle this issue; however, little attention has been paid on coordinating concurrent execution of distributed deadlock detection algorithms. Previous approaches may report incorrect results false negatives, and they are inefficient due to lack of proper coordination of concurrent execution. In this paper, we present a novel concurrent coordination algorithm for distributed generalized deadlock detection. The proposed algorithm aims to avoid false negatives and improve the performance when concurrently executing deadlock detection in a distributed system. Our algorithm adopts diffusion computation to distribute probe messages and employs priority-based method to coordinate concurrent algorithm instances. Priority carried in the received probe messages will be locally recorded by each initiator. Instead of being suspended by higher priority algorithm instances, lower priority algorithm instances can accomplish deadlock detection locally. The initiator with the highest priority will receive and collect all related resource requests information from lower priority instances in a hierarchical manner and perform global deadlock detection at last. We evaluate our algorithm on a bunch of event-driven simulations. The experimental results show that our approach can achieve better accuracy and efficiency compared to previous approaches.\",\n \"Title: Building and Analyzing of Enterprise Network: A Case Study on China Automobile Supply Network.\\nYear: 2016\\n\\nAbstract: Social business moves beyond linear, process-driven organizations to create new, dynamic, networked businesses that focus on customer value. Enterprise network EN is used to support social business by maximizing current and future opportunities and facilitate network-enabled processes, which can lead to value co-creation. EN is a multi-level hypergraph model with enterprises, employees, products and other related entities. In this paper the authors refine the EN model and present the foundation of EN to support social businesses. Then they introduce a case study on China automobile supply network CASN. For the similarity with social networks, they verify power-law and small world theories in EN with statistical results on this data set. These theories are fitful in EN, but some new characteristics exist. The structure of EN consists of star-shaped clusters and the authors extract ego networks taking suppliers and manufacturers as the ego respectively. With the structure and distribution features of EN, they present the enterprise business similarity analysis method based on common-neighbors. And they also introduce the tentative work to detect Dunbar circles in EN. To analyze the data in a more intuitional and effective way, the authors use some data visualization tools to process the data in EN.\",\n \"Title: Auto-tuning Performance of MPI Parallel Programs Using Resource Management in Container-Based Virtual Cloud\\nYear: 2016\\n\\nAbstract: Load imbalance problem is one of the major obstacles to achieving optimal performance of High Performance Computing applications. The approach of trying to distribute the problem pieces to each node with the hope of balancing execution time has limits since the performance depends not only on data size but also on many other dynamic factors. This paper describes an approach that uses adaptive resource management enabled by the container-based virtualization to solve the load imbalance problem of MPI programs running in the cloud. Our techniques dynamically adjust CPU resource allocation to MPI processes running as container instances according to the current program execution state and system resource status. The resource allocation among MPI processes is adjusted in two ways: the intra-host level, which dynamically adjusts resources within a host, and the inter-host level, which migrates containers together with MPI processes from one host to another host. We have implemented and evaluated our approach on Amazon EC2 platform using real-world scientific benchmarks and applications, which demonstrates that the performance can be improved up to 31% (with an average of 15%) when compared with the baseline.\",\n \"Title: Migrating GIS Big Data Computing from Hadoop to Spark: An Exemplary Study Using Twitter\\nYear: 2016\\n\\nAbstract: Recent research has demonstrated that social media could provide valuable spatio-temporal data about users activities. However, information extraction and computation from big amount of data pose various challenges. To effectively process massive datasets, several platforms have been developed. Our previous study [20] explored Hadoop-based cloud computing for processing big amount of social media data [9] to study geographic distributions of social media users. In this paper, we investigate an emerging system named Spark and present a timely pilot experience on geospatial big data research. In our study, Spark has been utilized to perform some classic geospatial analyses like K-Nearest Neighbors (KNN), geographic mean and median points, and the distribution of the median points. Our design is tested on an Amazon EC2 cluster. An exemplary study using 60GB, 120GB and 180GB Twitter data has demonstrated the performance achievements by migrating computing tasks from Hadoop to Spark. In our experiments, the Spark-based solution can be up to 2.3x faster than the Hadoop-based solution due to its in-memory processing and coarse-grained resource allocation strategy. In the paper, we also discuss optimization strategies on using Spark for different geospatial computing tasks.\",\n \"Title: A leader election based deadlock detection algorithm in distributed systems.\\nYear: 2016\\n\\nAbstract: Deadlock detection is an important and challenge work in distributed systems. Thing becomes more complex when multiple deadlock detection algorithm instances executing currently in the system. In this paper, we propose a leader election based deadlock detection algorithm in distributed system. Our algorithm aims to improve the performance in the condition of concurrent execution. In addition, our algorithm can provide a certain extent of fault tolerance after a current leader fails. We have proved the liveness and safety property of our algorithm. Simulation results show that our algorithm obtains an order of magnitude performance improvement on message complexity.\",\n \"Title: Rnalocate: A Resource For Rna Subcellular Localizations\\nYear: 2017\\n\\nAbstract: Increasing evidence has revealed that RNA subcellular localization is a very important feature for deeply understanding RNA's biological functions after being transported into intra-or extra-cellular regions. RNALocate is a web-accessible database that aims to provide a high-quality RNA subcellular localization resource and facilitate future researches on RNA function or structure. The current version of RNALocate documents more than 37 700 manually curated RNA subcellular localization entries with experimental evidence, involving more than 21 800 RNAs with 42 subcellular localizations in 65 species, mainly including Homo sapiens, Mus musculus and Saccha-romyces cerevisiae etc. Besides, RNA homology, sequence and interaction data have also been integrated into RNALocate. Users can access these data through online search, browse, blast and visualization tools. In conclusion, RNALocate will be of help in elucidating the entirety of RNA subcellular localization, and developing new prediction methods.\",\n \"Title: MRapid: An Efficient Short Job Optimizer on Hadoop\\nYear: 2017\\n\\nAbstract: Data have been generated and collected at an accelerating pace. Hadoop has made analyzing large scale data much simpler to developers/analysts using commodity hardware. Interestingly, it has been shown that most Hadoop jobs have small input size and do not run for long time. For example, higher level query languages, such as Hive and Pig, would handle a complex query by breaking it into smaller adhoc ones. Although Hadoop is designed for handling complex queries with large data sets, we found that it is highly inefficient to operate at small scale data, despite a new Uber mode was introduced specifically to handle jobs with small input size. In this paper, we propose an optimized Hadoop extension called MRapid, which significantly speeds up the execution of short jobs. It is completely backward compatible to Hadoop, and imposes negligible overhead. Our experiments on Microsoft Azure public cloud show that MRapid can improve performance by up to 88% compared to the original Hadoop.\",\n \"Title: Mrsim: Mitigating Reducer Skew In Mapreduce\\nYear: 2017\\n\\nAbstract: MapReduce has emerged as a popular programming model in the field of data-intensive computing. This is due to its simplistic design, which provides ease of use for programmers, and its framework implementations such as Hadoop, which have been adopted by large business and technology companies. One significant issue in practical MapReduce applications is data skew: the imbalance in the amount of data assigned to each task. This causes some tasks to take much longer to finish than others and can significantly impact performance. Existing solutions for the data skew in reduce side increase the overhead that the users need to customize a novel partitioner for the specific application, or perform additional sampling processes before the map function begins. To mitigate the data skew in reduce side, which is called Reducer skew in this paper, we proposed a load balancing strategy based on load statistics, namely MRSIM. To gets the input data distribution in reduce stage, MRSIM computed the statistics while preparing data, which makes full use of the shuffle stage in MapReduce. To balance the load of entire cluster, MRSIM reallocated reduce tasks on the heavy nodes to idle ones according to the data distribution. In addition, by introducing the load feedback mechanism, MRSIM further improved the cluster's performance when running complex applications. We evaluated MRSIM in YARN (Hadoop 2.2.0), the experimental results show that our MRSIM outperformed the default strategy in native Hadoop greatly, the improvement in execution time reached 17%\",\n \"Title: Hierarchical Spark: A Multi-Cluster Big Data Computing Framework\\nYear: 2017\\n\\nAbstract: Nowadays, with the increasing burst of newly generated data everyday, as well as the vast expanding needs for corresponding data analyses, grand challenges have been brought to big data computing platforms. Computing resources in a single cluster are often not able to fulfill the computing capability needs. The requests of distributed computing resources are dramatically arising. In addition, with increasing popularity of cloud computing platforms, many organizations with data security concerns are more favor to hybrid cloud, a multi-cluster environment composed by both public cloud and private cloud in purpose of keeping sensitive data local. All these scenarios show great necessity of migrating big data computing to multi-cluster environment. In this paper, we present a hierarchical multi-cluster big data computing framework built upon Apache Spark. Our framework supports combination of heterogeneous Spark computing clusters. With an integrated controller within the framework, it also facilitates ability for submitting, monitoring, executing of Spark workflow. Our experimental results show that the proposed framework not only enables possibility of distributing Spark workflow throughout multiple clusters, but also provides significant performance improvement compared to single cluster environment by optimizing utilization of multi-cluster computing resources.\",\n \"Title: Log-based Abnormal Task Detection and Root Cause Analysis for Spark\\nYear: 2017\\n\\nAbstract: Application delays caused by abnormal tasks arecommon problems in big data computing frameworks. Anabnormal task in Spark, which may run slowly withouterror or warning logs, not only reduces its resident node'sperformance, but also affects other nodes' efficiency.Spark log files report neither root causes of abnormal tasks,nor where and when abnormal scenarios happen. AlthoughSpark provides a “speculation” mechanism to detect stragglertasks, it can only detect tailed stragglers in each stage. Sincethe root causes of abnormal happening are complicated, thereare no effective ways to detect root causes.This paper proposes an approach to detect abnormality andanalyzes root causes using Spark log files. Unlike commononline monitoring or analysis tools, our approach is a pureoff-line method that can analyze abnormality accurately. Ourapproach consists of four steps. First, a parser preprocessesraw log files to generate structured log data. Second, ineach stage of Spark application, we choose features relatedto execution time and data locality of each task, as well asmemory usage and garbage collection of each node. Third,based on the selected features, we detect where and whenabnormalities happen. Finally, we analyze the problems usingweighted factors to decide the probability of root causes. In thispaper, we consider four potential root causes of abnormalities,which include CPU, memory, network, and disk. The proposedmethod has been tested on real-world Spark benchmarks.To simulate various scenario of root causes, we conductedinterference injections related to CPU, memory, network,and Disk. Our experimental results show that the proposedapproach is accurate on detecting abnormal tasks as well asfinding the root causes\",\n \"Title: Detecting and resolving deadlocks in mobile agent systems.\\nYear: 2017\\n\\nAbstract: Mobile agents environment is a new application paradigm with unique features such as mobility and autonomy. Traditional deadlock detection algorithms in distributed computing systems do not work well in mobile agent systems due to the unique feature property of the mobile agent. Existing deadlock detection and resolution algorithms in mobile agent systems have limitations such as performance inefficiency and duplicate detection/resolution when multiple mobile agents simultaneously detect/resolve the same deadlock. To address these problems, we propose an improved deadlock detection and resolution algorithm that adopts priority-based technique and lazy reaction strategy. The priority-based technique aims to ensure that there is only one instance of deadlock detection and resolution, and it also helps reduce mobile agent movement and data traffic together with the lazy reaction strategy. The liveness and safety properties of the proposed algorithm are proved in this paper. Theoretical analysis and experimental results show that the proposed algorithm provides better performance in terms of agent movement, data traffic, and execution time.\",\n \"Title: ISAT: An intelligent Web service selection approach for improving reliability via two-phase decisions.\\nYear: 2018\\n\\nAbstract: Due to stochasticity and uncertainty of malicious Web services over the Internet, it becomes difficult to select reliable services while meeting non-functional requirements in service-oriented systems. To avoid the unreliable real-world process of obtaining services, this paper proposes a novel service selection approach via two-phase decisions for enhancing the reliability of service-oriented systems. In the first-phase decision, we define the problem of finding reliable service candidates as a multiple criteria decision making (MCDM) problem. Then, we construct a decision model to address the problem. In the second-phase decision, we define the problem of selecting services based on non-functional requirements as an optimization problem. Finally, we propose a convex hull based approach for solving the optimization problem. Large-scale and real-world experiments are conducted to show the advantages of the proposed approach. The evaluation results confirm that our approach achieves higher success rate and less computation time to guarantee the reliability when compared to the other state-of-the-art approaches.\",\n \"Title: A Semi-Supervised Two-Stage Approach To Learning From Noisy Labels\\nYear: 2018\\n\\nAbstract: The recent success of deep neural networks is powered in part by large-scale well-labeled training data. However, it is a daunting task to laboriously annotate an ImageNet-like dateset. On the contrary, it is fairly convenient, fast, and cheap to collect training images from the Web along with their noisy labels. This signifies the need of alternative approaches to training deep neural networks using such noisy labels. Existing methods tackling this problem either try to identify and correct the wrong labels or reweigh the data terms in the loss function according to the inferred noisy rates. Both strategies inevitably incur errors for some of the data points. In this paper, we contend that it is actually better to ignore the labels of some of the data points than to keep them if the labels are incorrect, especially when the noisy rate is high. After all, the wrong labels could mislead a neural network to a bad local optimum. We suggest a two-stage framework for the learning from noisy labels. In the first stage, we identify a small portion of images from the noisy training set of which the labels are correct with a high probability. The noisy labels of the other images are ignored. In the second stage, we train a deep neural network in a semi-supervised manner. This framework effectively takes advantage of the whole training set and yet only a portion of its labels that are most likely correct. Experiments on three datasets verify the effectiveness of our approach especially when the noisy rate is high.\",\n \"Title: Optimizing MapReduce Partitioner Using Naive Bayes Classifier.\\nYear: 2017\\n\\nAbstract: Data locality and data skew on the reduce side are two essential issues in MapReduce. Improving data locality can decrease network traffic by moving reduce tasks to the nodes where the input data of reduce tasks is located. Data skew will lead to load imbalance among reducer nodes. Partitioning is an important operation of MapReduce because it determines the destinations of map output and could significantly affect the data amount of shuffle. Therefore, an effective partitioner can improve MapReduce performance by increasing data locality and decreasing data skew on the reduce side. Previous studies considering the two essential issues have ignored the fact that for different types of jobs, the priority of data locality and data skew on the reduce side may produce different effects on the execution time. In this paper, we propose a novel partitioner based on naive Bayes classifier, namely, BAPM, which achieves better performance through optimizing data locality and data skew by leveraging the naive Bayes classifier, i.e., considering job type and bandwidth as classification attributes. Our experiments are performed in a Hadoop cluster with 31 nodes and the results show that BAPM speeds up the computing performance of MapReduce by up to 19.26% compared to the native Hadoop.\",\n \"Title: Improving the Improved Training of Wasserstein GANs: A Consistency Term and Its Dual Effect.\\nYear: 2018\\n\\nAbstract: Despite being impactful on a variety of problems and applications, the generative adversarial nets (GANs) are remarkably difficult to train. This issue is formally analyzed by cite{arjovsky2017towards}, who also propose an alternative direction to avoid the caveats in the minmax two-player training of GANs. The corresponding algorithm, namely, Wasserstein GAN (WGAN) hinges on the 1-Lipschitz continuity of the discriminators. In this paper, we propose a novel approach for enforcing the Lipschitz continuity in the training procedure of WGANs. Our approach seamlessly connects WGAN with one of the recent semi-supervised learning approaches. As a result, it gives rise to not only better photo-realistic samples than the previous methods but also state-of-the-art semi-supervised learning results. In particular, to the best of our knowledge, our approach gives rise to the inception score of more than 5.0 with only 1,000 CIFAR10 images and is the first that exceeds the accuracy of 90% the CIFAR10 datasets using only 4,000 labeled images.\",\n \"Title: Public Opinion Spamming: A Model for Content and Users on Sina Weibo.\\nYear: 2018\\n\\nAbstract: Microblogs serve hundreds of millions of active users, but have also attracted large numbers of spammers. While traditional spam often seeks to endorse specific products or services, nowadays there are increasingly also paid posters intent on promoting particular views on hot topics and influencing public opinion. In this work, we fill an important research gap by studying how to detect such opinion spammers and their micro-manipulation of public opinion. Our model is unsupervised and adopts a Bayesian framework to distinguish spammers from other classes of users. Experiments on a Sina Weibo hot topic dataset demonstrate the effectiveness of the proposed approach. A further diachronic analysis of the collected data demonstrates that public opinion spammers have developed sophisticated techniques and have seen success in subtly manipulating the public sentiment.\",\n \"Title: Tuning Performance of Spark Programs\\nYear: 2018\\n\\nAbstract: Along with the explosive growth of data, there is a great demand to speedup the ability to process them. Although there are several platforms such as Spark that have made analysis easier to developers, the performance tuning for such platforms meanwhile becomes complex. In this paper, we propose an efficient performance optimization engine called Hedgehog to evaluate the performance based on \\\"Law of Diminishing Marginal Utility\\\" and give an optimal configuration setting. The initial experiments show that our optimization can gain 19.6% performance improvement compared to the naive configuration by tuning only 3 parameters.\",\n \"Title: NPIY : A novel partitioner for improving mapreduce performance.\\nYear: 2018\\n\\nAbstract: MapReduce is an effective and widely-used framework for processing large datasets in parallel over a cluster of computers. Data skew, cluster heterogeneity, and network traffic are three issues that significantly affect the performance of MapReduce applications. However, the hash-based partitioner in the native Hadoop does not consider these factors. This paper proposes a new partitioner for Yarn (Hadoop 2.6.0), namely, NPIY, which adopts an innovative parallel sampling method to distribute intermediate data. The paper makes the following major contributions: (1) NPIY mitigates data skew in MapReduce applications; (2) NPIY considers the heterogeneity of computing resources to balance the loads among Reducers; (3) NPIY reduces the network traffic in the shuffle phase by trying to retain intermediate data on those nodes running both map and reduce tasks. Compared with the native Hadoop and other popular strategies, NPIY can reduce execution time by up to 41.66% and 58.68% in homogeneous and heterogeneous clusters, respectively. We further customize NPIY for parallel image processing, and the execution time has been improved by 28.8% compared with the native Hadoop.\",\n \"Title: A fault tolerant election-based deadlock detection algorithm in distributed systems\\nYear: 2018\\n\\nAbstract: Deadlock detection in a distributed system without shared memory is important to ensure the reliability of the system. It becomes more complex when multiple deadlock detection algorithm instances execute concurrently in the system. In addition, the problem of communication disconnection between computing nodes or processes makes deadlock detection more difficult. Existing centralized algorithms suffer from single point failure of the central controller (due to communication disconnection), and they are performance-inefficient in the case of concurrent execution. In this paper, we extend our previous work (Lu et al. ) and propose a fault tolerant deadlock detection algorithm in distributed systems. The extended proposed algorithm can tolerate a certain extent of communication disconnection between computing nodes or processes. A central controller is used to collect requesting conditions, construct a wait-for graph, and detect deadlocks. The proposed algorithm can select a new central controller if the current central leader fails due to communication disconnections. The liveness and safety properties of the proposed algorithm are proved in this paper. Experimental results show that the proposed algorithm provides better performance than most of existing algorithms in terms of message number, data traffic, and execution time. In addition, the proposed algorithm provides additional fault tolerance compared to existing deadlock detection algorithms in the case of communication disconnection.\",\n \"Title: Five Shades of Untruth: Finer-Grained Classification of Fake News.\\nYear: 2018\\n\\nAbstract: Prior work on algorithmic truth assessment on unreliable content, has mostly pursued binary classifiers - factual vs. fake - and disregarded the finer shades of untruth. On the other hand, manual analysis of questionable content has proposed a more fine-grained classification: distinguishing between hoaxes, irony and propaganda, or the six-way rating by the PolitiFact community. In this paper, we present a principled approach to capture these finer shades in automatically assessing and classifying news articles and claims. We systematically explore a variety of signals from both news and social media, and give an analysis of the underlying features.\",\n \"Title: Detecting Anomaly in Big Data System Logs Using Convolutional Neural Network\\nYear: 2018\\n\\nAbstract: Nowadays, big data systems are being widely adopted by many domains for offering effective data solutions, such as manufacturing, healthcare, education, and media. Big data systems produce tons of unstructured logs that contain buried valuable information. However, it is a daunting task to manually unearth the information and detect system anomalies. A few automatic methods have been developed, where the cutting-edge machine learning technique is one of the most promising ways. In this paper, we propose a novel approach for anomaly detection from big data system logs by leveraging Convolutional Neural Networks (CNN). Different from other existing statistical methods or traditional rule-based machine learning approaches, our CNN-based model can automatically learn event relationships in system logs and detect anomaly with high accuracy. Our deep neural network consists of logkey2vec embeddings, three 1D convolutional layers, dropout layer, and max-pooling. According to our experiment, our CNN-based approach has better accuracy(reaches to 99%) compared to other approaches using Long Short term memory (LSTM) and Multilayer Perceptron (MLP) on detecting anomaly in Hadoop Distributed File System (HDFS) logs.\",\n \"Title: Ftsgd: An Adaptive Stochastic Gradient Descent Algorithm For Spark Mllib\\nYear: 2018\\n\\nAbstract: The proliferation of massive datasets and the surge of interests in big data analytics have popularized a number of novel distributed data processing platforms such as Hadoop and Spark. Their large and growing ecosystems of libraries enable even novice to take advantage of the latest data analytics and machine learning algorithms. However, time-consuming data synchronization and communications in iterative algorithms on large-scale distributed platforms can lead to significant performance inefficiency. MLlib is Spark's scalable library consisting of common machine learning algorithms, many of which employ Stochastic Gradient Descent (SGD) to find minima or maxima by iterations. However, the convergence can be very slow if gradient data are synchronized on each iteration.In this work, we optimize the current implementation of SGD in Spark's MLlib by reusing data partition for multiple times within a single iteration to find better candidate weights in a more efficient way. Whether using multiple local iterations within each partition is dynamically decided by the 68-95-99.7 rule. We also design a variant of momentum algorithm to optimize step size in every iteration. This method uses a new adaptive rule that decreases the step size whenever neighboring gradients show differing directions of significance. Experiments show that our adaptive algorithm is more efficient and can be 7 times faster compared to the original MLlib's SGD.\",\n \"Title: A Proximal Zeroth-Order Algorithm for Nonconvex Nonsmooth Problems.\\nYear: 2018\\n\\nAbstract: In this paper, we focus on solving an important class of nonconvex optimization problems which includes many problems for example signal processing over a networked multi-agent system and distributed learning over networks. Motivated by many applications in which the local objective function is the sum of smooth but possibly nonconvex part, and non-smooth but convex part subject to a linear equality constraint, this paper proposes a proximal zeroth-order primal dual algorithm (PZO-PDA) that accounts for the information structure of the problem. This algorithm only utilize the zeroth-order information (i.e., the functional values) of smooth functions, yet the flexibility is achieved for applications that only noisy information of the objective function is accessible, where classical methods cannot be applied. We prove convergence and rate of convergence for PZO-PDA. Numerical experiments are provided to validate the theoretical results.\",\n \"Title: Localized Video Coding\\nYear: 2019\\n\\nAbstract: This paper describes a novel scheme of video coding structure called Localized Video Coding (LVC) infra structure. Unlike the existing video coding standards, LVC is a video coding structure that is parallel-friendly. LVC will divide a video sequence into several sub-sequences and process them independently. LVC is a nontraditional way to parallelize video coding process, aimed at solving the existing problems of heat dissipation in chips. Every sub-sequence can be coded or decoded in a different processing unit and LVC can control a processing unit to sleep or work. Hence we can easily transfer the tasks from an overheated processing unit to a normal one. In this paper we will illustrate the LVC structure and show the results. Then we will provide an example of an improved method that shows a massive reduction in the processing time of a whole video sequence as well an encouraging video coding performance compared with the HEVC Tiles [1].\",\n \"Title: A Reinforcement Learning Based Resource Management Approach for Time-critical Workloads in Distributed Computing Environment\\nYear: 2018\\n\\nAbstract: Many data analyzing applications highly rely on timely response from execution, and are referred as time-critical data analyzing applications. Due to frequent appearing of gigantic amount of data and analytical computations, running them on large scale distributed computing environments is often advantageous. The workload of big data applications is often hybrid, i.e., contains a combination of time-critical and regular non-time-critical applications. Resource management for hybrid workloads in complex distributed computing environment is becoming more critical and needs more studies. However, it is difficult to design rule-based approaches best suited for such complex scenarios because many complicated characteristics need to be taken into account.Therefore, we present an innovative reinforcement learning (RL) based resource management approach for hybrid workloads in distributed computing environment. We utilize neural networks to capture desired resource management model, use reinforcement learning with designed value definition to gradually improve the model and use ε-greedy methodology to extend exploration along the reinforcement process. The extensive experiments show that our obtained resource management solution through reinforcement learning is able to greatly surpass the baseline rule-based models. Specifically, the model is good at reducing both the missing deadline occurrences for time-critical applications and lowering average job delay for all jobs in the hybrid workloads. Our reinforcement learning based approach has been demonstrated to be able to provide an efficient resource manager for desired scenarios.\",\n \"Title: Aet Vs. Aed: Unsupervised Representation Learning By Auto-Encoding Transformations Rather Than Data\\nYear: 2019\\n\\nAbstract: The success of deep neural networks often relies on a large amount of labeled examples, which can be difficult to obtain in many real scenarios. To address this challenge, unsupervised methods are strongly preferred for training neural networks without using any labeled data. In this paper, we present a novel paradigm of unsupervised representation learning by Auto-Encoding Transformation (AET) in contrast to the conventional Auto-Encoding Data (AED) approach. Given a randomly sampled transformation, AET seeks to predict it merely from the encoded features as accurately as possible at the output end. The idea is the following: as long as the unsupervised features successfully encode the essential information about the visual structures of original and transformed images, the transformation can be well predicted. We will show that this AET paradigm allows us to instantiate a large variety of transformations, from parameterized, to non-parameterized and GAN-induced ones. Our experiments show that AET greatly improves over existing unsupervised approaches, setting new state-of-the-art performances being greatly closer to the upper bounds by their fully supervised counterparts on CIFAR-10, ImageNet and Places datasets.\",\n \"Title: Texture and Position Based Multiple Transform for Inter-Predicted Residue Coding\\nYear: 2018\\n\\nAbstract: The next generation video coding standard beyond HEVC is in the study. Many efficient coding tools are introduced to the hybrid framework. Among the new coding tools, EMT focuses on transform module by multiple transform modes to improve the transform efficiency. However, EMT is implemented on residual blocks ignoring the details of the residual distribution. Hence, EMT has some drawbacks to be repaired. In this paper, we propose a method, named texture and position based multiple transform (TPBMT), to refine EMT in the framework. What's more, the efficiency of TPBMT is verified by sufficient experimental data. When implemented on JEM7.0, TPBMT attains average 1.26%, 1.66% and 1.62% for Y, U and V, respectively, up to 6.07%, 5.19% and 4.87%.\",\n \"Title: Naive Bayes Classifier Based Partitioner For Mapreduce\\nYear: 2018\\n\\nAbstract: MapReduce is an effective framework for processing large datasets in parallel over a cluster. Data locality and data skew on the reduce side are two essential issues in MapReduce. Improving data locality can decrease network traffic by moving reduce tasks to the nodes where the reducer input data is located. Data skew will lead to load imbalance among reducer nodes. Partitioning is an important feature of MapReduce because it determines the reducer nodes to which map output results will be sent. Therefore, an effective partitioner can improve MapReduce performance by increasing data locality and decreasing data skew on the reduce side. Previous studies considering both essential issues can be divided into two categories: those that preferentially improve data locality, such as LEEN, and those that preferentially improve load balance, such as CLP. However, all these studies ignore the fact that for different types of jobs, the priority of data locality and data skew on the reduce side may produce different effects on the execution time. In this paper, we propose a naive Bayes classifier based partitioner, namely, BAPM, which achieves better performance because it can automatically choose the proper algorithm (LEEN or CLP) by leveraging the naive Bayes classifier, i.e., considering job type and bandwidth as classification attributes. Our experiments are performed in a Hadoop cluster, and the results show that BAPM boosts the computing performance of MapReduce. The selection accuracy reaches 95.15%. Further, compared with other popular algorithms, under specific bandwidths, the improvement BAPM achieved is up to 31.31%.\",\n \"Title: Energy Efficiency Optimization with CoMP in Homogeneous Network of TD-LTE-A System\\nYear: 2017\\n\\nAbstract: Coordinated Multiple Point (CoMP) Transmission/Reception could increase the transmission date rate of cell edge users and extend the cell coverage. Meanwhile, to meet the requirement of green communications, the researchers have studied how to improve the energy efficiency. In this paper, the energy consumption of eNodeB in CoMP is analyzed and the energy efficiency is optimized. Then, the joint optimization of resource allocation, beamforming and power allocation is performed to maximize the energy efficiency in CoMP homogeneous networks. The relationship between system energy efficiency and system spectrum efficiency is also discussed in this paper.\",\n \"Title: Cpgavas2, An Integrated Plastome Sequence Annotator And Analyzer\\nYear: 2019\\n\\nAbstract: We previously developed a web server CPGAVAS for annotation, visualization and GenBank submission of plastome sequences. Here, we upgrade the server into CPGAVAS2 to address the following challenges: (i) inaccurate annotation in the reference sequence likely causing the propagation of errors; (ii) difficulty in the annotation of small exons of genes petB, petD and rps16 and trans-splicing gene rps12; (iii) lack of annotation for other genome features and their visualization, such as repeat elements; and (iv) lack of modules for diversity analysis of plastomes. In particular, CPGAVAS2 provides two reference datasets for plastome annotation. The first dataset contains 43 plastomes whose annotation have been validated or corrected by RNA-seq data. The second one contains 2544 plastomes curated with sequence alignment. Two new algorithms are also implemented to correctly annotate small exons and trans-splicing genes. Tandem and dispersed repeats are identified, whose results are displayed on a circular map together with the annotated genes. DNA-seq and RNA-seq data can be uploaded for identification of single-nucleotide polymorphism sites and RNA-editing sites. The results of two case studies show that CPGAVAS2 annotates better than several other servers. CPGAVAS2 will likely become an indispensible tool for plastome research and can be accessed from http://www.herbalgenomics.org/cpgavas2.\",\n \"Title: Learning to Adaptively Scale Recurrent Neural Networks.\\nYear: 2019\\n\\nAbstract: Recent advancements in recurrent neural network (RNN) research have demonstrated the superiority of utilizing multiscale structures in learning temporal representations of time series. Currently, most of multiscale RNNs use fixed scales, which do not comply with the nature of dynamical temporal patterns among sequences. In this paper, we propose Adaptively Scaled Recurrent Neural Networks (ASRNN), a simple but efficient way to handle this problem. Instead of using predefined scales, ASRNNs are able to learn and adjust scales based on different temporal contexts, making them more flexible in modeling multiscale patterns. Compared with other multiscale RNNs, ASRNNs are bestowed upon dynamical scaling capabilities with much simpler structures, and are easy to be integrated with various RNN cells. The experiments on multiple sequence modeling tasks indicate ASRNNs can efficiently adapt scales based on different sequence contexts and yield better performances than baselines without dynamical scaling abilities.\",\n \"Title: Depthwise Convolution is All You Need for Learning Multiple Visual Domains.\\nYear: 2019\\n\\nAbstract: There is a growing interest in designing models that can deal with images from different visual domains. If there exists a universal structure in different visual domains that can be captured via a common parameterization, then we can use a single model for all domains rather than one model per domain. A model aware of the relationships between different domains can also be trained to work on new domains with less resources. However, to identify the reusable structure in a model is not easy. In this paper, we propose a multi-domain learning architecture based on depthwise separable convolution. The proposed approach is based on the assumption that images from different domains share cross-channel correlations but have domain-specific spatial correlations. The proposed model is compact and has minimal overhead when being applied to new domains. Additionally, we introduce a gating mechanism to promote soft sharing between different domains. We evaluate our approach on Visual Decathlon Challenge, a benchmark for testing the ability of multi-domain models. The experiments show that our approach can achieve the highest score while only requiring 50% of the parameters compared with the state-of-the-art approaches.\",\n \"Title: LADRA: Log-based abnormal task detection and root-cause analysis in big data processing with Spark\\nYear: 2019\\n\\nAbstract: As big data processing is being widely adopted by many domains, massive amount of generated data become more reliant on the parallel computing platforms for analysis, wherein Spark is one of the most widely used frameworks. Spark’s abnormal tasks may cause significant performance degradation, and it is extremely challenging to detect and diagnose the root causes. To that end, we propose an innovative tool, named LADRA, for log-based abnormal tasks detection and root-cause analysis using Spark logs. In LADRA, a log parser first converts raw log files into structured data and extracts features. Then, a detection method is proposed to detect where and when abnormal tasks happen. In order to analyze root causes we further extract pre-defined factors based on these features. Finally, we leverage General Regression Neural Network (GRNN) to identify root causes for abnormal tasks. The likelihood of reported root causes are presented to users according to the weighted factors by GRNN. LADRA is an off-line tool that can accurately analyze abnormality without extra monitoring overhead. Four potential root causes, i.e., CPU, memory, network, and disk I/O, are considered. We have tested LADRA atop of three Spark benchmarks by injecting aforementioned root causes. Experimental results show that our proposed approach is more accurate in the root cause analysis than other existing methods.\",\n \"Title: NATTACK: Learning the Distributions of Adversarial Examples for an Improved Black-Box Attack on Deep Neural Networks.\\nYear: 2019\\n\\nAbstract: Powerful adversarial attack methods are vital for understanding how to construct robust deep neural networks (DNNs) and for thoroughly testing defense techniques. In this paper, we propose a black-box adversarial attack algorithm that can defeat both vanilla DNNs and those generated by various defense techniques developed recently. Instead of searching for an optimal adversarial example for a benign input to a targeted DNN, our algorithm finds a probability density distribution over a small region centered around the input, such that a sample drawn from this distribution is likely an adversarial example, without the need of accessing the DNNu0027s internal layers or weights. Our approach is universal as it can successfully attack different neural networks by a single algorithm. It is also strong; according to the testing against 2 vanilla DNNs and 13 defended ones, it outperforms state-of-the-art black-box or white-box attack methods for most test cases. Additionally, our results reveal that adversarial training remains one of the best defense techniques, and the adversarial examples are not as transferable across defended DNNs as them across vanilla DNNs.\",\n \"Title: Frame-Recurrent Video Inpainting by Robust Optical Flow Inference.\\nYear: 2019\\n\\nAbstract: In this paper, we present a new inpainting framework for recovering missing regions of video frames. Compared with image inpainting, performing this task on video presents new challenges such as how to preserving temporal consistency and spatial details, as well as how to handle arbitrary input video size and length fast and efficiently. Towards this end, we propose a novel deep learning architecture which incorporates ConvLSTM and optical flow for modeling the spatial-temporal consistency in videos. It also saves much computational resource such that our method can handle videos with larger frame size and arbitrary length streamingly in real-time. Furthermore, to generate an accurate optical flow from corrupted frames, we propose a robust flow generation module, where two sources of flows are fed and a flow blending network is trained to fuse them. We conduct extensive experiments to evaluate our method in various scenarios and different datasets, both qualitatively and quantitatively. The experimental results demonstrate the superior of our method compared with the state-of-the-art inpainting approaches.\",\n \"Title: Robust Sparse Regularization: Simultaneously Optimizing Neural Network Robustness and Compactness.\\nYear: 2019\\n\\nAbstract: Deep Neural Network (DNN) trained by the gradient descent method is known to be vulnerable to maliciously perturbed adversarial input, aka. adversarial attack. As one of the countermeasures against adversarial attack, increasing the model capacity for DNN robustness enhancement was discussed and reported as an effective approach by many recent works. In this work, we show that shrinking the model size through proper weight pruning can even be helpful to improve the DNN robustness under adversarial attack. For obtaining a simultaneously robust and compact DNN model, we propose a multi-objective training method called Robust Sparse Regularization (RSR), through the fusion of various regularization techniques, including channel-wise noise injection, lasso weight penalty, and adversarial training. We conduct extensive experiments across popular ResNet-20, ResNet-18 and VGG-16 DNN architectures to demonstrate the effectiveness of RSR against popular white-box (i.e., PGD and FGSM) and black-box attacks. Thanks to RSR, 85% weight connections of ResNet-18 can be pruned while still achieving 0.68% and 8.72% improvement in clean- and perturbed-data accuracy respectively on CIFAR-10 dataset, in comparison to its PGD adversarial training baseline.\",\n \"Title: A Novel Derived Mode for Block Partitioning Structure in Video Coding\\nYear: 2019\\n\\nAbstract: In the exploration of the next video coding standard, the quadtree plus binary tree block structure (QTBT) has been adopted in the joint video exploration team. QTBT splits a block into sub-blocks following a structure of quadtree or binary tree. However, all the split modes of QTBT are symmetrical, which is less efficient in coding asymmetrical motion. In addition, the lower signaling efficiency of side information occurs when a successive binary split in the same direction is selected. Motivated by these observations, the derived mode (DM) based on QTBT is proposed in this letter, where six novel DMs are introduced. The DM further splits a QTBT node into several sub-blocks, and each sub-block can be predicted independently. Among the DMs, four asymmetrical split modes are introduced to improve the capability of coding asymmetrical motion, and two 4-split modes are designed to improve signaling efficiency. Moreover, higher efficiency than QTBT, a 0.99% BD-rate saving on average, is verified by extensive experiments.\",\n \"Title: Defending Against Adversarial Attacks Using Random Forest\\nYear: 2019\\n\\nAbstract: As deep neural networks (DNNs) have become increasingly important and popular, the robustness of DNNs is the key to the safety of both the Internet and physical world. Unfortunately, some recent studies show that adversarial examples, which are hard to be distinguished from real examples, can easily fool DNNs and manipulate their predictions. Upon observing that adversarial examples are mostly generated by gradient-based methods, in this paper, we first propose to use a simple yet very effective non-differentiable hybrid model that combines DNNs and random forests, rather than hide gradients from attackers, to defend against the attacks. Our experiments show that our model can successfully and completely defend the white-box attacks, has a lower transferability, and is quite resistant to three representative types of black-box attacks; while at the same time, our model achieves similar classification accuracy as the original DNNs. Finally, we investigate and suggest a criterion to define where to grow random forests in DNNs.\",\n \"Title: Analyzing Deep Neural Network'S Transferability Via Frechet Distance\\nYear: 2021\\n\\nAbstract: Transfer learning has become the de facto practice to reuse a deep neural network (DNN) that is pre-trained with abundant training data in a source task to improve the model training on target tasks with smaller-scale training data. In this paper, we first investigate the correlation between the DNN's pre-training performance in the source task and their transfer results in the downstream tasks. We find that high performance of a pre-trained model does not necessarily imply high transferability. We then propose a metric, named Frechet Pre-train Distance, to estimate the transferability of a deep neural network. By applying the proposed Frechet Pre-train Distance, we are able to identify the optimal pre-trained checkpoint, and then achieve high transferability on downstream tasks. Finally, we investigate several factors impacting DNN's transferability including normalization, different networks and learning rates. The results consistently support our conclusions.\",\n \"Title: SODA: A Semantics-Aware Optimization Framework for Data-Intensive Applications Using Hybrid Program Analysis\\nYear: 2021\\n\\nAbstract: In the era of data explosion, a growing number of data-intensive computing frameworks, such as Apache Hadoop and Spark, have been proposed to handle the massive volume of unstructured data in parallel. Since programming models provided by these frameworks allow users to specify complex and diversified user-defined functions (UDFs) with predefined operations, the grand challenge of tuning up entire...\",\n \"Title: A Lazy Approach to Long-Horizon Gradient-Based Meta-Learning.\\nYear: 2021\\n\\nAbstract: Gradient-based meta-learning relates task-specific models to a meta-model by gradients. By this design, an algorithm first optimizes the task-specific models by an inner loop and then backpropagates meta-gradients through the loop to update the meta-model. The number of inner-loop optimization steps has to be small (e.g., one step) to avoid high-order derivatives, big memory footprints, and the risk of vanishing or exploding meta-gradients. We propose an intuitive teacher-student scheme to enable the gradient-based meta-learning algorithms to explore long horizons by the inner loop. The key idea is to employ a student network to adequately explore the search space of task-specific models (e.g., by more than ten steps), and a teacher then takes a\\\"leap\\\"toward the regions probed by the student. The teacher not only arrives at a high-quality model but also defines a lightweight computation graph for meta-gradients. Our approach is generic; it performs well when applied to four meta-learning algorithms over three tasks: few-shot learning, long-tailed classification, and meta-attack.\",\n \"Title: CTIN: Robust Contextual Transformer Network for Inertial Navigation.\\nYear: 2022\\n\\nAbstract: Recently, data-driven inertial navigation approaches have demonstrated their capability of using well-trained neural networks to obtain accurate position estimates from inertial measurement units (IMUs) measurements. In this paper, we propose a novel robust Contextual Transformer-based network for Inertial Navigation (CTIN) to accurately predict velocity and trajectory. To this end, we first design a ResNet-based encoder enhanced by local and global multi-head self-attention to capture spatial contextual information from IMU measurements. Then we fuse these spatial representations with temporal knowledge by leveraging multi-head attention in the Transformer decoder. Finally, multi-task learning with uncertainty reduction is leveraged to improve learning efficiency and prediction accuracy of velocity and trajectory. Through extensive experiments over a wide range of inertial datasets (e.g., RIDI, OxIOD, RoNIN, IDOL, and our own), CTIN is very robust and outperforms state-of-the-art models.\",\n \"Title: ADCNN: Towards learning adaptive dilation for convolutional neural networks\\nYear: 2022\\n\\nAbstract: Dilated convolution kernels are constrained by their shared dilation, keeping them from being aware of diverse spatial contents at different locations. We address such limitations by formulating the dilation as trainable weights with respect to individual positions. We propose Adaptive Dilation Convolutional Neural Networks (ADCNN), a light-weighted extension that allows convolutional kernels to adjust their dilation value based on different contents at the pixel level. Unlike previous content-adaptive models, ADCNN dynamically infers pixel-wise dilation via modeling feed-forward inter-patterns, which provides a new perspective for developing adaptive network structures other than sampling kernel spaces. Our evaluation results indicate ADCNNs can be easily integrated into various backbone networks and consistently outperform their regular counterparts on various visual tasks.\",\n \"Title: Multi-stream dynamic video Summarization\\nYear: 2022\\n\\nAbstract: With vast amounts of video content being uploaded to the Internet every minute, video summarization becomes critical for efficient browsing, searching, and indexing of visual content. Nonetheless, the spread of social and egocentric cameras creates an abundance of sparse scenarios captured by several devices, and ultimately required to be jointly summarized. In this paper, we discuss the problem of summarizing videos recorded independently by several dynamic cameras that intermittently share the field of view. We present a robust framework that (a) identifies a diverse set of important events among moving cameras that often are not capturing the same scene, and (b) selects the most representative view(s) at each event to be included in a universal summary. Due to the lack of an applicable alternative, we collected a new multi-view egocentric dataset, Multi-Ego. Our dataset is recorded simultaneously by three cameras, covering a wide variety of real-life scenarios. The footage is annotated by multiple individuals under various summarization configurations, with a consensus analysis ensuring a reliable ground truth. We conduct extensive experiments on the compiled dataset in addition to three other standard benchmarks that show the robustness and the advantage of our approach in both supervised and unsupervised settings. Additionally, we show that our approach learns collectively from data of varied number-of-views and orthogonal to other summarization methods, deeming it scalable and generic.\",\n \"Title: Unifying Obstacle Detection, Recognition, and Fusion Based on the Polarization Color Stereo Camera and LiDAR for the ADAS\\nYear: 2022\\n\\nAbstract: The perception module plays an important role in vehicles equipped with advanced driver-assistance systems (ADAS). This paper presents a multi-sensor data fusion system based on the polarization color stereo camera and the forward-looking light detection and ranging (LiDAR), which achieves the multiple target detection, recognition, and data fusion. The You Only Look Once v4 (YOLOv4) network is utilized to achieve object detection and recognition on the color images. The depth images are obtained from the rectified left and right images based on the principle of the epipolar constraints, then the obstacles are detected from the depth images using the MeanShift algorithm. The pixel-level polarization images are extracted from the raw polarization-grey images, then the water hazards are detected successfully. The PointPillars network is employed to detect the objects from the point cloud. The calibration and synchronization between the sensors are accomplished. The experiment results show that the data fusion enriches the detection results, provides high-dimensional perceptual information and extends the effective detection range. Meanwhile, the detection results are stable under diverse range and illumination conditions.\",\n \"Title: Continuous sliding mode control for the translational oscillator with a rotating actuator system\\nYear: 2022\\n\\nAbstract: The stabilization and disturbance rejection of the translational oscillator with a rotating actuator (TORA) are considered in this paper. To deal with the control issues, a novel continuous sliding mode control method is designed for the TORA system. Compared with existing sliding mode control methods for the TORA system, the proposed method here is continuous. Specifically, first, a global diffeomorphism is introduced for the model of the TORA system. Then, an elaborate sliding manifold is constructed, and a continuous sliding mode control scheme is developed to ensure the convergence of the sliding manifold. Furthermore, rigorous theoretical analysis is given. Finally, simulation tests are carried out, and the obtained simulation results demonstrate that the proposed method exhibits superior stabilization control performance and strong robustness.\",\n \"Title: A three-dimensional measurement method for binocular endoscopes based on deep learning\\nYear: 2022\\n\\nAbstract: In the practice of clinical endoscopy, the precise estimation of the lesion size is quite significant for diagnosis. In this paper, we propose a three-dimensional (3D) measurement method for binocular endoscopes based on deep learning, which can overcome the poor robustness of the traditional binocular matching algorithm in texture-less areas. A simulated binocular image dataset is created from the target 3D data obtained by a 3D scanner and the binocular camera is simulated by 3D rendering software to train a disparity estimation model for 3D measurement. The experimental results demonstrate that, compared with the traditional binocular matching algorithm, the proposed method improves the accuracy and disparity map generation speed by 48.9% and 90.5%, respectively. This can provide more accurate and reliable lesion size and improve the efficiency of endoscopic diagnosis.\",\n \"Title: A dynamic handover scheme based on bidirectional VLC channel in multi-user attocell networks\\nYear: 2022\\n\\nAbstract: Light fidelity (LiFi) would be a potential optical wireless communications technology for future mixed-spectrum 5G/6G indoor attocell network, which uses light-emitting diodes based as an optical antenna and offers Gbits capacity. For this scenario, a dynamic handover scheme based on bidirectional visible light communications (VLC) channel is proposed, which uses the uplink light sources to characterize terminal’s movement status for the mobility and make the handover decision in contrast to the unidirectional links. The uplink reference signal received power and the movement state are examined, and the created algorithm is executed in the bidirectional VLC test bed. The experimental results show that the proposed method will reduce the terminal’s handover rate by up to 45% and increase the optical network throughput by up to 26% at the experimental data rate compared with the skipping handover scheme for indoor LiFi network.\",\n \"Title: Reinforcement Learning-Based Visible Light Positioning and Handover Scheme With Stereo-Camera\\nYear: 2022\\n\\nAbstract: Aimed at solving the problems of frequent handover and large overheads for positioning in 6G, this paper proposes a reinforcement learning (RL)-based visible light positioning (VLP) handover scheme by means of a stereo camera system in which a lower handover rate and higher positioning accuracy were achieved simultaneously. Because of the randomness of the distribution location of indoor light sources and obstacles, even if the parameters of light sources and receivers are consistent, users cannot rely on unitary and invariable parameters to determine whether to change the access point (AP) in the process of moving, especially in some special locations. The proposed scheme, which decomposed the user's moving track at different speeds in a VLP system to optimize selecting the AP by using RL at each step, was exhibited and tested. Experimental results show that the proposed scheme achieved millimeter-level positioning accuracy, improved the normalized reward by over 40% and reduced the handover rate by 87% and 78% compared to the immediate handover (IHO) and dwell handover (DHO) methods concurrently.\",\n \"Title: Bug-Transformer: Automated Program Repair Using Attention-Based Deep Neural Network\\nYear: 2022\\n\\nAbstract: In this paper, we propose a novel transformer-based deep neural network model to learn semantic bug patterns from a corpus of buggy/fixed codes, then generate correct ones automatically. Transformer is a deep learning model relying entirely on attention mechanism to model global dependencies between input and output. Although there are a few endeavors to repair programs by learning neural language models (NLM), many special program properties, such as structure and semantics of an identifier, are not considered in embedding input sequence and designing model effectively, which results in undesired performance. In the proposed Bug-Transformer, we design a novel context abstraction mechanism to better support neural language models. Specifically, it is capable of 1) compressing code information but preserving the key structure and semantics, which provides more thorough information for NLM models, 2) renaming identifiers and literals based on their lexical scopes, structural and semantic information, to reduce code vocabulary size and 3) reserving keywords and selected idioms (domain- or developer-specific vocabularies) for better understanding code structure and semantics. Hence, Bug-Transformer adequately embeds code structural and semantic information into input data and optimize attention-based transformer neural network to well handle code features in order to improve learning tasks for bug repair. We evaluate the performance of the proposed work comprehensively on three datasets (Java code corpora) and generate patches to buggy code using a beam search decoder. The experimental results show that our proposed work outperforms the-state-of-art techniques: Bug-Transformer can successfully predict 54.81%, 34.45%, and 42.40% of the fixed code in these three datasets, respectively, which outperform the baseline models. These success rates steadily increase along with the increase of beam size. Besides, the overall syntactic correctness of all patches remains above 97%, 96%, and 50% on the three benchmarks, respectively, regardless of the beam size.\",\n \"Title: Experimental Verification of the Modified PSA Algorithm\\nYear: 2022\\n\\nAbstract: Being abundant and non-polluted, solar energy is an increasingly desirable energy source. Growing research is concerned about maximum solar energy acquisition from solar panels, especially in the automatic sun-tracking of the solar panels. This paper presents a modified algorithm based on the \\\"PSA algorithm\\\" proposed in the 2001, and presents a new automatic solar tracking system with a two-axis is designed based on the algorithm. The PSA modified algorithm is used to calculate the sun's horizontal azimuth and zenith angle combined with time, longitude, latitude, and other information. This experiment of the prototype mainly composed of a microcontroller, a global positioning system (GPS) module, a digital compass, a tilt sensor, a 555 timer, and gates, optical couples, a H-bridge and two stepper motors. Then a series of experiments are conducted using the proposed prototype in Tianjin City. Measured zenith angle values were collected and recorded based on the PSA modified algorithm and the original PSA algorithm, compared with the actual Zenith Angle of the Sun in Tianjin City. The comparison curves of Zenith Angle show that the measurement accuracy of the modified PSA algorithm is higher than that of the PSA original algorithm.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":102,"string":"102"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":280,"string":"280"}}},{"rowIdx":281,"cells":{"question_id":{"kind":"string","value":"Xinyu Shao"},"question":{"kind":"string","value":"Generate an abstract for the title \"A hybrid honey-bees mating optimization algorithm for assembly sequence planning problem\" using the following items: Assembly sequence planning, mathematical model, hybrid honey-bees mating optimization algorithm, Multipoint Precedence Crossover, simulated annealing algorithm."},"answer":{"kind":"string","value":"Assembly sequence planning (ASP) refers to taking the related constraint factors such as assembly features, assembly tools and machines into consideration to generate a low-cost feasible sequence. In this paper, a mathematical model of assembly sequence planning problem based on connectors is constructed, and a hybrid honey-bees mating optimization (HBMO) algorithm is proposed for solving this ASP problem. The proposed algorithm has two main innovative features compared to the conventional HBMO algorithm. Firstly, a crossover operator, called Multipoint Precedence Crossover (MPX), is proposed, which can avoid the generation of infeasible solutions and preserve the meaningful characteristics of the queen and broods. Secondly, worker bees utilize the simulated annealing (SA) algorithm as a local search method to improve the broods, which makes the proposed algorithm achieve the right balance between intensification and diversification. The hybrid HBMO algorithm is tested on three practical instances and compared with other approaches, such as Guided-GAs, MAs (memetic algorithm) and AIS (artificial immune systems). The superior results on these practical instances validate the effectiveness of the proposed algorithm."},"correct_answer":{"kind":"string","value":"Assembly sequence planning (ASP) refers to taking the related constraint factors such as assembly features, assembly tools and machines into consideration to generate a low-cost feasible sequence. In this paper, a mathematical model of assembly sequence planning problem based on connectors is constructed, and a hybrid honey-bees mating optimization (HBMO) algorithm is proposed for solving this ASP problem. The proposed algorithm has two main innovative features compared to the conventional HBMO algorithm. Firstly, a crossover operator, called Multipoint Precedence Crossover (MPX), is proposed, which can avoid the generation of infeasible solutions and preserve the meaningful characteristics of the queen and broods. Secondly, worker bees utilize the simulated annealing (SA) algorithm as a local search method to improve the broods, which makes the proposed algorithm achieve the right balance between intensification and diversification. The hybrid HBMO algorithm is tested on three practical instances and compared with other approaches, such as Guided-GAs, MAs (memetic algorithm) and AIS (artificial immune systems). The superior results on these practical instances validate the effectiveness of the proposed algorithm."},"documents":{"kind":"list like","value":["Title: Integration of process planning and scheduling-A modified genetic algorithm-based approach\nYear: 2009\n\nAbstract: Traditionally, process planning and scheduling for parts were carried out in a sequential way, where scheduling was done after process plans had been generated. Considering the fact that the two functions are usually complementary, it is necessary to integrate them more tightly so that performance of a manufacturing system can be improved greatly. In this paper, a new integration model and a modified genetic algorithm-based approach have been developed to facilitate the integration and optimization of the two functions. In the model, process planning and scheduling functions are carried out simultaneously. In order to improve the optimized performance of the modified genetic algorithm-based approach, more efficient genetic representations and operator schemes have been developed. Experimental studies have been conducted and the comparisons have been made between this approach and others to indicate the superiority and adaptability of this method. The experimental results show that the proposed approach is a promising and very effective method for the integration of process planning and scheduling.","Title: Constraint-based Collaborative Design\nYear: 2006\n\nAbstract: Collaborative design can be characterized by different level constraints that describe basic elements of design process such as human, information and resource. In design, satisfied solutions to constraints must occur to arrive at a final design result. Few collaborative design systems exist for adequately representing constraints, and formally combining them from different disciplines. The main contribution of this paper is to introduce a methodology for analyzing the constraints in collaborative design. A hierarchy of fuzzy constraint networks is presented along with a methodology for creating interlinks between different levels of the hierarchy. The solution methodology is illustrated with an example. The paper concludes with directing attention to current challenges and recommendations for research","Title: A Reduction Algorithm Based on the Degree of Attribute Discernibility\nYear: 2006\n\nAbstract: This paper studies the problem of attribute discernibility reduction and introduces some new concepts to Rough Set theory, such as Secondary Core, Regeneration Matrix and the degree of attribute discernibility. An attribute reduction algorithm has been proposed based on the concept of highest discernibility. The efficacy of this algorithm has been verified by practical application in a diagnostic system of mechanical loader, which displays notably decrease in information gathering requirement and lowers down the overall cost without any loss of accuracy.","Title: An effective hybrid particle swarm optimization algorithm for multi-objective flexible job-shop scheduling problem\nYear: 2009\n\nAbstract: Flexible job-shop scheduling problem (FJSP) is an extension of the classical job-shop scheduling problem. Although the traditional optimization algorithms could obtain preferable results in solving the mono-objective FJSP. However, they are very difficult to solve multi-objective FJSP very well. In this paper, a particle swarm optimization (PSO) algorithm and a tabu search (TS) algorithm are combined to solve the multi-objective FJSP with several conflicting and incommensurable objectives. PSO which integrates local search and global search scheme possesses high search efficiency. And, TS is a meta-heuristic which is designed for finding a near optimal solution of combinatorial optimization problems. Through reasonably hybridizing the two optimization algorithms, an effective hybrid approach for the multi-objective FJSP has been proposed. The computational results have proved that the proposed hybrid algorithm is an efficient and effective approach to solve the multi-objective FJSP, especially for the problems on a large scale.","Title: Fuzzy multiple attributive group decision-making for conflict resolution in collaborative design\nYear: 2006\n\nAbstract: Most conflicts in collaborative design are categorized as the problem of fuzzy multiple attributive group decision-making (FMAGDM). Both fuzzy assessments and the aggregation of multiple experts' opinions should be considered in the conflict resolution process. This paper presents a new approach for the problem, where cooperation degree (CD) and reliability degree (RD) are introduced for aggregating the vague experts' opinions. Furthermore, a fuzzy multiple attributive group decision-making expert system (FMAGDMES) is proposed to provide an interactive way to solve conflicts in collaborative environment. It is an intelligent integrated system because it combines fuzzy set theory with the method of group opinion aggregation. The vehicle performance evaluation as a real case is used to validate the efficiency of the proposed expert system, which is implemented by using c++.","Title: Multi-agent based integration of process planning and scheduling\nYear: 2009\n\nAbstract: Traditionally, process planning and scheduling were performed sequentially, where scheduling was done after process plans had been generated. Considering the fact that the two functions are usually complementary, it is necessary to integrate them more tightly so that the performance of a manufacturing system can be improved greatly. In this paper, a Multi-agent-based approach has been developed to facilitate the integration of the two functions. In the approach, the two functions are carried out simultaneously, and an optimization agent based on an evolutionary algorithm is used to manage the interactions and communications between agents to enable proper decisions to be made. To verify the feasibility and performance of the proposed approach, an experimental study has been conducted and comparisons have been made between this approach and some previous works. The experimental results show the proposed approach has achieved significant improvement.","Title: Development of a design structure matrix partitioning method towards effective design collaboration.\nYear: 2012\n\nAbstract: The difficulties in design collaboration stem from the managerial complexity in terms of the interactions and interdependencies among the respective development activities. This paper introduces a simple structural partitioning algorithm of design structure matrix, basing on dependency relationships among tasks via tracing the input tasks chain. The algorithm is composed of four modules, which are used to organise and transform design tasks into input model, cycle model, group model and execution ordering model correspondingly. Cycle matrix is created to partition the task set into individual groups that are with different interdependency levels. Coupled and unordered individual task set could be converted into uncoupled, ordered task clusters. The illustrative case studies on automotive industry has verified the efficiency of the proposed algorithm, which could partition the development processes into different execution clusters to improve the concurrence and collaboration of product development tasks. Copyright © 2012 Inderscience Enterprises Ltd.","Title: A Web services based distributed multidisciplinary design optimization framework to ship design\nYear: 2011\n\nAbstract: Ship design is a complex process, which contains many coupled disciplines and needs the collaboration among geographical distributed design resources. Multidisciplinary Design Optimization (MDO) provides a promising way to ship design compared to traditional spiral design approach. As the important enabling tool, MDO framework is vital to the successful implementation of MDO problems. In this paper, at the base of surveying the state of the art of some notable MDO frameworks, a Web services and Isight based distributed ship MDO framework is proposed, which provides an easy way to integrate distributed design, analysis, optimization services, namely various tools and programs, to jointly implement ship design. At the same time, according to the requirements of ship design, some new and extended function modules are added, which incorporates a number of existing technologies such as workflow, component technology.","Title: Mathematical modeling and evolutionary algorithm-based approach for integrated process planning and scheduling\nYear: 2010\n\nAbstract: Traditionally, process planning and scheduling were performed sequentially, where scheduling was implemented after process plans had been generated. Considering their complementarity, it is necessary to integrate these two functions more tightly to improve the performance of a manufacturing system greatly. In this paper, a mathematical model of integrated process planning and scheduling has been formulated. And, an evolutionary algorithm-based approach has been developed to facilitate the integration and optimization of these two functions. To improve the optimized performance of the approach, efficient genetic representation and operator schemes have been developed. To verify the feasibility and performance of the proposed approach, experimental studies have been conducted and comparisons have been made between this approach and some previous works. The experimental results show that the integrated process planning and scheduling is necessary and the proposed approach has achieved significant improvement.","Title: A PSO-FUZZY Group decision-making Support System in vehicle performance evaluation\nYear: 2010\n\nAbstract: Group decision-making (GD) is a fuzzy problem with high complexity and difficult to be handled. Usually the rule-based Group decision-making Support System (GDSS) is used to solve GD problem. But the definition of fuzzy rules and membership functions in GDSS are generally affected by subjective decision. So the rationality of GDSS is difficult to be judged. In this paper, the particle swarm optimization (PSO) algorithm is introduced to improve the fuzzy rule base through optimize the position and shape of fuzzy rule set and weights of rules. A PSO-fuzzy GDSS is set up and used to a real application of vehicle performance evaluation. According to the contrast of three methods: Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), non-weighted fuzzy rule base, and PSO-fuzzy GDSS, the result shows that weighted fuzzy rule base after PSO optimized is better than non-weighted fuzzy rule base, and the evaluation values of PSO-fuzzy GDSS are very close to the TOPSIS. Therefore, the PSO-fuzzy GDSS is an efficient method for vehicle performance evaluation and can be applied to more domains.","Title: Integration of variable precision rough set and fuzzy clustering: an application to knowledge acquisition for manufacturing process planning\nYear: 2005\n\nAbstract: Knowledge acquisition plays a significant role in the knowledge-based intelligent process planning system, but there remains a difficult issue. In manufacturing process planning, experts often make decisions based on different decision thresholds under uncertainty. Knowledge acquisition has been inclined towards a more complex but more necessary strategy to obtain such thresholds, including confidence, rule strength and decision precision. In this paper, a novel approach to integrating fuzzy clustering and VPRS (variable precision rough set) is proposed. As compared to the conventional fuzzy decision techniques and entropy-based analysis method, it can discover association rules more effectively and practically in process planning with such thresholds. Finally, the proposed approach is validated by the illustrative complexity analysis of manufacturing parts, and the analysis results of the preliminary tests are also reported.","Title: HUST-CDMS: A Test-bed for Collaborative Design and Manufacturing\nYear: 2006\n\nAbstract: A test-bed (HUST-CDMS) for collaborative product design and manufacturing is described in this paper. This test-bed is constructed by using a CORBA and MAS based system architecture, where diverse and heterogeneous design and manufacturing resources are MAS-based agentified and CORBA-based encapsulated as resource agents and subsequently integrated in the system. These resource agents communicate and interact with each other by means of agent interoperation and human-machine interaction to achieve a collaborative design and manufacturing environment, aiming at reducing the lead time and costs","Title: An agent-based approach for integrated process planning and scheduling\nYear: 2010\n\nAbstract: Traditionally, process planning and scheduling were performed sequentially, where scheduling was done after process plans had been generated. Considering the fact that these two functions are usually complementary, it is necessary to integrate them more tightly so that the performance of a manufacturing system can be improved greatly. In this paper, an agent-based approach has been developed to facilitate the integration of these two functions. In the approach, the two functions are carried out simultaneously, and an optimization agent based on an evolutionary algorithm is used to manage the interactions and communications between agents to enable proper decisions to be made. To verify the feasibility and performance of the proposed approach, experimental studies have been conducted and comparisons have been made between this approach and some previous works. The experimental results show the proposed approach has achieved significant improvement.","Title: Relay Node Deployment Based Small World Effect in Hierarchical Industrial Wireless Sensor Networks\nYear: 2013\n\nAbstract: The industrial wireless sensor networks (IWSNs) brings several advantages over traditional wired industrial monitoring and control systems. The communication reliability of IWSNs has to be guaranteed as the real-time field data need to be transmitted to the control system. The specific requirements of IWSNs have brought challenges to the deployment strategy of sensors in industrial environments. Obviously the network architecture has a significant influence on the performance of IWSNs. Therefore, in this paper, we place three types of nodes in a manufacturing shop to monitor equipment situation, production status and environment. We construct an IWSN with small world characteristics through the random additions of efficient relay nodes and short-cuts at a certain probability. The sensor data will be transmitted in multi-hop to the server quickly and exactly through the small world IWSN. In addition, the proposed deployment strategy will ensure balanced energy-usage among the nodes in the network. Simulation results show that the built network topology possesses the property of rapid transmission to reduce the transmission relay drastically and has good robustness. Compared to the flat single-tier network structure of homogeneous sensor nodes, the small world networks utilizing heterogeneous elements will be preferred in IWSNs.","Title: A Web services and process-view combined approach for process management of collaborative product development\nYear: 2009\n\nAbstract: Collaborative Product Development (CPD) across enterprises has been recognized as an effective strategy to connect multi-enterprise wide project teams to develop more competitive products. Process management is vital to the successful implementation of CPD in a multi-enterprise environment. In this paper, a novel Web Services (WSs) and process-view combined approach has been developed to manage the dynamic and distributed process of CPD to enhance the workflow interoperability among heterogeneous Workflow Management Systems (WMSs) of enterprises. Meanwhile, a hybrid P2P based WMSs framework has been built to provide an open and scalable architecture to deploy inter-enterprises collaboration. A software prototype system has been implemented using the open JXTA platform, and the collaborative development of a motorcycle has been used as a test case to validate the proposed approach and the prototype system.","Title: A product module identification approach based on axiomatic design and design structure matrix.\nYear: 2012\n\nAbstract: In terms of creating customized products rapidly, modularity is deemed to be an effective developmental strategy for handling product variety and intricacy. In order to develop reasonable modular product architecture with physically detachable modules, a new systematic and structured approach for product modularization based on axiomatic design and design structure matrix is proposed. The product is decomposed hierarchically into its functional, physical, and process domains using axiomatic design method. After transformation from design matrix to design structure matrix, the pertinence design structure matrices of design parameters describing function, structure, and manufacturing process are constructed. Besides, a manufacturing process similarity matrix of design parameters is established. Finally, a genetic algorithm combined with the minimal description length is employed to realize the modularization optimization after integration of the above matrices. To illustrate the effectiveness of the proposed methodology, an indoor air conditioner unit is presented as a demonstrative example.","Title: Analytical Target Cascading Based on Physical Programming\nYear: 2010\n\nAbstract: Analytical Target Cascading (ATC) is a product development tool that computes component design specifications so that the final system design is consistent and meets design targets. It is a promising methodology for decomposition of complex system design and optimization. However, ATC has some shortcomings inherently. In this paper, after analyzing the theory and model of ATC, a more promising method entitled Analytical Target Cascading Based on Physical Programming (ATC-PP) is proposed. This new approach is intended to substantially place the design process into a more flexible and practical framework by adding the advantages of Physical Programming (PP) into ATC. And the preference function which is proposed in PP is used to definite the deviation between response and linking variables in ATC in the new method. It can completely eliminate the need for assigning weight coefficient, which is the object of the typical computational bottleneck in large design optimization problems. And it could also give the designers' preferences in practical design. Finally, the validity of ATC-PP is approved by studying an anchor design problem.","Title: A Vr-Based Simulation System For Glass Pressing\nYear: 2008\n\nAbstract: The integration with virtual reality is a new boost to CAD and CAE. This paper presents a research effort aimed at creating a desktop-based, low-cost and independent VR-based simulation system for glass pressing, which integrates the forming process simulation and mold motion simulation. The skeletal animation technique is employed for Motion Simulation of the mold The stereoscopic view of the virtual system is achieved by Crystal Eyes shutter glasses, with C++ language and OpenGL support library selected as the development tool. With the stereoscopic display of the mold design, pressing motion and numerical CAE results, the system enables engineers to gain a cohesive view of mold structure, assembly issues, and possible forming faults. it can also support training of students and engineers to acquire the theoretical know-how, practical skills, and the problem troubleshooting techniques of glass pressing. (C) 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 315-320. 2008: Published online in Wiley InterScience (www.interscience.wiley.com): DOI 10.1002/cae.20216","Title: A process-view approach for cross-organizational workflows management\nYear: 2010\n\nAbstract: Workflow management for cross-organizational business processes presents a significant challenge recently. The development and implementation of new methodologies and technologies are imperative to tackle this challenge. The process-view approach provides a promising way to facilitate cross-organizational workflows management, especially when it is combined with powerful workflow modeling methods. With the assumption that workflow modeling methods in cooperative organizations are interoperable, a process-view and timed colored Petri net (TCPN) combined approach is proposed to manage cross-organizational workflows, including the formal definition, the mapping from TCPN workflow models to process-view workflow models in which the aspects of control flow and data flow are considered together, and the collaborative execution mechanisms of cross-organizational workflow instances. A hybrid P2P based decentralized workflow management system (WMS) combined with the process-view approach is proposed and built, which is placed on the top of the open JXTA platform and provides a flexible and scalable architecture for cross-organizational workflows management. At last, the cross-organizational workflows management for the distributed development of a circular saw has been used as a test case for system validation.","Title: A new approach for predicting and collaborative evaluating the cutting force in face milling based on gene expression programming\nYear: 2013\n\nAbstract: Cutting force is one of the fundamental elements that can provide valuable insight in the investigation of cutter breakage, tool wear, machine tool chatter, and surface finish in face milling. Analyzing the relationship between process factors and cutting force is helpful to set the process parameters of the future cutting operation and further improve production quality and efficiency. Since cutting force is impacted by the inherent uncertainties in the machining process, how to predict the cutting force presents a significant challenge. In the meantime, face milling is a complex process involving multiple experts with different domain knowledge, collaborative evaluation of the cutting force model should be conducted to effectively evaluate the constructed predictive model. Gene Expression Programming (GEP) combines the advantages of the Genetic Algorithm (GA) and Genetic Programming (GP), and has been successfully applied in function mining and formula finding. In this paper, a new approach to predict the face milling cutting force based on GEP is proposed. At the basis of defining a GEP environment for the cutting force prediction, an explicit predictive model has been constructed. To verify the effectiveness of the proposed approach, a case study has been conducted. The comparisons between the proposed approach and some previous works show that the constructed model fits very well with the experimental data and can predict the cutting force with a high accuracy. Moreover, in order to better apply the constructed predictive models in actual face milling process, a collaborative model evaluation method is proposed to provide a distributed environment for geographical distributed experts to evaluate the constructed predictive model collaboratively, and four kinds of collaboration mode are discussed.","Title: Scheduling Mixed-Model Assembly Lines with Cost Objectives by a Hybrid Algorithm\nYear: 2008\n\nAbstract: This paper is concerned about how to optimize the input sequence for a mixed-model assembly line (MMAL) with limited intermediate buffers. Three optimization objectives are considered simultaneously: minimizing the total production rate variation, the total setup, and the total assembly cost. The mathematical model is presented by incorporating the three objectives. Since the problem is NP-hard, a hybrid algorithm based on genetic algorithm (GA) and simulated annealing (SA), is proposed for solving the model. The performance of the proposed algorithm is compared with a genetic algorithm for different-sized sequencing problems in MMALs that consist of different number of machines and different production plans. The computational results show that the proposed hybrid algorithm finds solutions with better quality and often needs a smaller number of generations to converge to a final stable state, especially in the case of large-sized problems.","Title: A Genetic Algorithm for Integration of Process Planning and Scheduling Problem\nYear: 2008\n\nAbstract: Traditionally, process planning and scheduling for parts are carried out in a sequential way, where scheduling is done after process plans have been generated. Considering the two functions are usually complementary, there is a great potential to integrate them more tightly so that greater performance and higher productivity of a manufacturing system can be achieved. In this paper, a genetic algorithm-based approach has been developed to facilitate the integration and optimization of these two functions. To improve the optimized performance of the genetic algorithm-based approach, efficient genetic representations and operator schemes have been developed. Experiment studies have been conducted. The experimental results show that the proposed approach is a promising and very effective method for the integration of process planning and scheduling.","Title: On-Line Simulation for Shop Floor Control in Manufacturing Execution System\nYear: 2008\n\nAbstract: This paper presents and discusses the structure and components of a novel on-line simulation system for real-time shop floor control in manufacturing execution system (MES). The framework of the simulation system is constructed in association with a MES. The on-line simulation system can collect data from physical shop floor and communicate with a scheduling controller through the MES. Furthermore, MES can provide much of the dynamic information required by the simulation model, and can also execute the shop floor control strategy which is solved by the simulation system. A multi-pass simulation method is introduced and applied to control the shop floor.","Title: Reactive scheduling in a job shop where jobs arrive over time\nYear: 2013\n\nAbstract: The paper considers the dynamic job shop scheduling problem (DJSSP) with job release dates which arises widely in practical production systems. The principle characteristic of DJSSP considered in the paper is that the jobs arrive continuously in time and the attributes of the jobs, such as the release dates, routings and processing times are not known in advance, whereas in the classical job shop scheduling problem (CJSSP), it is assumed that all jobs to be processed are available at the beginning of the scheduling process. Reactive scheduling approach is one of the effective approaches for DJSSP. In the paper, a heuristic is proposed to implement the reactive scheduling of the jobs in the dynamic production environment. The proposed heuristic decomposes the original scheduling problem into a number of sub problems. Each sub problem, in fact, is a dynamic single machine scheduling problem with job release dates. The scheduling technique applied in theproposed heuristic is priority scheduling, which determines the next state of the system based on priority values of certain system elements. The system elements are prioritized with the help of scheduling rules (SRs). An approach based on gene expression programming (GEP) is also proposed in the paper to construct efficient SRs for DJSSP. The rules constructed by GEP are evaluated in the comparison of the rules constructed by GP and several prominent human made rules selected from literatures on extensive problem sets with respect to various measures of performance.","Title: Design and implementation of a process-oriented intelligent collaborative product design system\nYear: 2004\n\nAbstract: With the competition between companies being fiercer and customers being more demanding, the efficiency of design decision-making must be improved to shorten the product design cycle. Intelligent collaborative product design is needed in the product design process. In this paper, based on the Analysis-Synthesis-Evaluation (ASE) design paradigm and the parameterization of product design, an agent that incorporates the working mechanism of expert systems is designed to assist a designer in his work. In line with the modularization of the product design, a module-based multi-agent system is developed and deployed according to the CORBA standards to facilitate the coordination among designers within the range of enterprises and even virtual enterprises. In the light of preliminary tests on the Internet, the agent and the agent system show some, advantages to increase the efficiency of the design coordination and decision-making in the product design process.","Title: Social aspects of collaborative design\nYear: 2008\n\nAbstract: Collaborative design is a complex process being carried out by distributed teams. Collaboration requires successful and efficient sharing of knowledge, negotiation, coordination and management of activities. In distributed environments, design members are moving to network forms through alliances and other collaborative relationships as a social network. This paper explores collaborative design process from a sociological viewpoint. A social factor-based architecture for collaborative design is investigated, with special attention given to patterns of social behavior and the organizations of those who participate in the design. Social factors thought to have played a role include perspectives, preference, attitudes, cognition, etc. The main contribution of this paper is to introduce a methodology for analyzing the social aspects of collaborative design. The paper concludes with directing attention to current challenges and recommendations for research.","Title: Optimization of manufacturing systems using Genetic Search and Muti-resolution simulation.\nYear: 2010\n\nAbstract: This paper presents a method for the optimization of manufacturing systems by using Genetic Search and Multi-level Modeling Multi-resolution Simulation. The method can realize genetic optimization for manufacturing systems by using multi-resolution simulation which is based on the multi-level modeling. This paper focuses on the design of the genetic optimization searching algorithm and the optimization of a complex manufacturing system, through the comprehensive use of relevant methods in order to optimize in parallel the target system's structure parameters and operational behaviors with a reasonable time-effectiveness performance. © 2010 IEEE.","Title: An effective modified Particle Swarm Optimization algorithm for process planning\nYear: 2010\n\nAbstract: In the modern manufacturing system, most jobs have a large number of flexible process plans. However, there is only one process plan can be selected for a job in the manufacturing process. Therefore, flexible process plans selection has become a crucial problem in a manufacturing environment. It is a combinatorial optimization problem to conduct operations selection and operations sequencing simultaneously with various constraints deriving from the practical workshop environment as well as the jobs to be processed. In this paper, a new method using a modified particle swarm optimization (PSO) algorithm is presented to optimize the process planning problem. To improve the optimization performance of the approach, efficient encoding and updating strategies have been developed. To verify the feasibility and performance of the proposed approach, a case study has been conducted. The results show that the proposed modified PSO algorithm can generate satisfactory solutions.","Title: A prior-knowledge input LSSVR metamodeling method with tuning based on cellular particle swarm optimization for engineering design\nYear: 2014\n\nAbstract: Engineering design is usually a daunting optimization task which often involving time-consuming, even computation-prohibitive process. To reduce the computational expense, metamodels are commonly used to replace the actual expensive simulations or experiments. In this paper, a new and efficient metamodeling method named prior-knowledge input least square support vector regression (PKI-LSSVR) is developed, in which samples from different levels of fidelity are incorporated to gain an accurate approximation with limited times of the high-fidelity (HF) expensive simulations. The low-fidelity (LF) output serves as a prior-knowledge of the real response function, and then is used as the input variables of least square support vector regression (LSSVR). When the corresponding HF response is gained, a function that maps the LF outputs to HF outputs is constructed via LSSVR. The predictive accuracy of LSSVR models is highly dependent on their learning parameters. Therefore, a novel optimization method, cellular particle swarm optimization (CPSO), is exploited to seek the optimal hyper-parameters for PKI-LSSVR in order to improve its generalization capability. To get a better optimization performance, a new neighborhood function is developed for CPSO where the global and local search is efficiently balanced by adaptively varied neighbor radius. Several numerical experiments and one engineering case verify the efficiency of the proposed PKI-LSSVR method. Sample quality merits including sample sizes and noise, and metamodel performance evaluation measures incorporating accuracy, robustness, and efficiency are considered.","Title: A cost-based selective maintenance decision-making method for machining line\nYear: 2011\n\nAbstract: Machine line is a type of manufacturing system in which machines are connected in series or in parallel. It is significant to ensure the reliability as well as to reduce the total cost of maintenance and failure losses in the maintenance programs of such systems. Cost-based selective maintenance decision-making, which is the best method for a selected group of machines in machine line is presented under limited maintenance durations. Fault losses and maintenance costs of a single machine under different maintenance actions i.e. minimal repair, preventive maintenance and overhaul on the fault rate of the machine are calculated. An algorithm combining the heuristic rules and tabu search is proposed to solve the presented selective maintenance model. Finally, a case study on the maintenance decision-making problem of a connecting rod machining line in the automobile engine workshop is presented to illustrate the applicability of the proposed method. The end result shows that the fault losses can be further reduced by the optimization of maintenance interval and maintenance duration. Copyright (C) 2010 John Wiley & Sons, Ltd.","Title: A Multi-agent System for Cross-Organizational Workflows Management Based on Process-View\nYear: 2007\n\nAbstract: Workflow interoperability across enterprises boundaries presents a significant challenge recently. Process-view provides a promising way to cross-organizational workflows design. A multi-agent system combined with Petri net based process-view approach is proposed to facilitate cross-organizational workflows management. Within this multi-agent system, a Petri net algebra model and a character string mapping algorithm are proposed to automate the mapping from a Petri net workflow model to a process-view workflow model; the synchronization points are added to integrated process-view workflow models to coordinate the execution of cross-organizational workflow instances.","Title: Reliability Assessment of Machining Accuracy on Support Vector Machine\nYear: 2008\n\nAbstract: In order to establish the reliability model of limited samples, a kind of support vector machine (SVM) tools LSSVM.M is used to process reliability assessment data. The choice of parameters is the key factor to affect the forecasting accuracy. To improve the accuracy, a method of advanced parameters choice is proposed, which consists of two steps. First step is to optimize the scope of parameters, gradually narrowing the initial large scope. The next step is to find out the optimal parameters. Finally, the reliability model of NC machining accuracy was established, and the prediction result in NC machining accuracy case proves that this method is valid and effective.","Title: An active learning genetic algorithm for integrated process planning and scheduling\nYear: 2012\n\nAbstract: In traditional approaches, process planning and scheduling are carried out sequentially, where scheduling is done separately after the process plan has been generated. However, the functions of these two systems are usually complementary. The traditional approach has become an obstacle to improve the productivity and responsiveness of the manufacturing system. If the two systems can be integrated more tightly, greater performance and higher productivity of a manufacturing system can be achieved. Therefore, the research on the integrated process planning and scheduling (IPPS) problem is necessary. In this paper, a new active learning genetic algorithm based method has been developed to facilitate the integration and optimization of these two systems. Experimental studies have been used to test the approach, and the comparisons have been made between this approach and some previous approaches to indicate the adaptability and superiority of the proposed approach. The experimental results show that the proposed approach is a promising and very effective method on the research of the IPPS problem.","Title: Interoperability Of Cross-Organizational Workflows Based On Process-View For Collaborative Product Development\nYear: 2008\n\nAbstract: Collaborative product development (CPD) has been widely accepted as an advanced collaboration paradigm that combines geographically distributed product development teams to develop product collaboratively and efficiently. Interoperability of cross-organizational workflows is important for CPD to facilitate the successful execution of the whole product development process across enterprises boundaries. This article, describes a timed colored petri net (TCPN) and process-view combined approach to construct cross-organizational workflows, and a three models framework of 'TCPN workflow models - Process- view workflow models - Integrated process-view workflow model' is proposed to realize the interoperability of cross-organizational workflows for CPD. A multi-agent system PVMAS provides a mediated architecture for distributed workflow management systems interoperability among cooperative enterprises. Under this architecture, a service discovery algorithm is provided for discovering the most suitable services enterprises need, a TCPN algebra model and a character string mapping algorithm are proposed to automate the mapping from a TCPN workflow model to a process-view workflow model, and the synchronization points are designated in the integrated process-view workflow model to coordinate the execution of cross-organizational workflow instances. Finally, a case study of the collaborative development of a motorcycle is presented to verify the validity of our approach for cross-organizational workflows interoperability in CPD.","Title: Sequencing Mixed-Model Assembly Lines with Limited Intermediate Buffers by a GA/SA-Based Algorithm\nYear: 2008\n\nAbstract: This study is concerned about how to optimize the input sequence of product models in Mixed-Model Assembly Lines (MMALs) with limited intermediate buffers. Two objectives are considered simultaneously: minimizing the variation in parts usage and minimizing the makespan. The mathematical model is presented by incorporating the two objectives according to their relative importance weights. A hybrid algorithm (GASA), based on a genetic algorithm (GA) and a simulated annealing algorithm (SA), is proposed for solving the model. The performance of the GASA is compared with the GA over various test problems. The results show that, in terms of solutions' quality, both the GASA and GA can find the same best solution for small-sized problems and the GASA performs better than the GA for mediate and large-sized problems. Moreover, the impact of buffer size on MMAL's performance is investigated.","Title: Analysis of horizontal machining center field failure data based on generalized linear mixed model - a case study\nYear: 2011\n\nAbstract: In order to assess the operational reliability of the horizontal machining center (HMC), field failure data for 14 HMCs over one year are collected from an engine plant of a large automobile manufacturing company in China. In contrast with the usual approach, which just pools the data from all copies under the assumption that each copy is modeled by the same power law processes (PLP), a new model based on the generalized linear mixed model (GLMM) is proposed for analyzing the failure data from all copies of HMC. A basic idea of this method is to assume heterogeneity among all copies of HMC; it is also found that the underlying model for each individual copy is a PLP model with different shape parameters and scale parameters in the GLMM model. This method can make inferences about both the population and each individual copy. Meanwhile, the modified Anderson-Darling test is adapted to the goodness-of-fit test of the model. The results of the analysis suggest that this method is effective to analyze reliability of HMC. Copyright (C) 2010 John Wiley & Sons, Ltd.","Title: Multi-objective Topology Optimization of Structures Using NN-OC Algorithms\nYear: 2007\n\nAbstract: Topology optimization problem, which involves many design variables, is commonly solved by finite element method, a method must recalculate structure-stiffness matrix each time of analysis. OC method is a good way to solve topology optimization problem, nevertheless, it can not solve multiobjective topology optimization problems. This paper introduces an effective solution to Multi-objective topology optimization problems by using Neural Network algorithms to improve the traditional OC method. Specifically, in each iteration, calculate the new neural network link weight vector by using the previous link weight vector in the last iteration and the compliance vector in the last time of optimization, then work out the impact factor of each optimization objective on the overall objective of the optimization in order to determine the optimal direction of each design variable.","Title: A process simulation based method for scheduling product design change propagation\nYear: 2012\n\nAbstract: It is expected by enterprises that design changes that occur in a complex product development process can be resolved in a cost-effective way so that products modified for new customer requirements or new technology can be launched into the market without increasing much cost and time. Usually there are different solutions or methods for design changes, which may have different impacts on the whole process. Since a complex product development process consists of many design tasks and different relationships among these tasks, it is not easy to analytically compute the completion time when change propagation finishes. In this paper a process simulation based method is proposed to select the most economic propagation path for each design change, which can reduce the total process time for changes occurring in the complex product development process. ''And/Or'' graph nodes are used to represent the input and output logics of each task in the design process. Mathematic models are developed to calculate the completion time of the change propagation process. Monte Carlo based simulation algorithms for finding feasible output paths and calculating impacts of input changes on tasks are developed in order to simulate the change propagation process. The objective function for scheduling design change propagations is obtained by the regression analysis of simulation results. And the best change propagation paths, which usually are not the real optimum of the original design process model, are given by optimizing the regression model with a commercial optimization package. The effect of the method is demonstrated with a study of change propagations in the motor cycle engine design process.","Title: A Novel Approach for Process Planning Using Polychromatic Sets and Fuzzy Sets\nYear: 2007\n\nAbstract: Process planning is a task that determines the detailed manufacturing steps for transforming a raw material into a completed part, by utilizing the available machining resources. It involves multiple decision-making activities, such as operation-type selection, operation-method (machine, tool, and tool approach direction) selection, and operations sequencing. This study aims to developing an approach for process planning based on polychromatic sets and fuzzy sets. A complete flow and model is established for processing method seeking, processing route generation, and optimal route selection. The verification, grounding on a true model, is performed for the proposed model to prove the well practicability of this method.","Title: A late acceptance hill-climbing algorithm for balancing two-sided assembly lines with multiple constraints\nYear: 2015\n\nAbstract: Two-sided assembly lines are widely applied to produce the large-sized high-volume products, such as buses and trucks. Balancing the lines is a vital design problem for the industries, and the problem is NP-hard. Besides the fundamental constraints of the conventional line balancing problem, some specific constraints may occur in the two-sided assembly line problem, including the zoning constraints, the positional constraints, and the synchronism constraints, which make the problem more complex. In this paper, an integer programming (IP) model is constructed and solved for the two-sided assembly line balancing problem which contains the above three constraints. A novel metaheuristic named late acceptance hill-climbing (LAHC) is also proposed to solve the problem effectively. The proposed algorithm is tested on several sets of instances. The computational results of the LAHC algorithm are compared with those of IP and the lower bounds of the instances. The experiment validates the effectiveness of the LAHC algorithm.","Title: An effective hybrid honey bee mating optimization algorithm for balancing mixed-model two-sided assembly lines.\nYear: 2015\n\nAbstract: Mixed-model two-sided assembly lines are widely used in a range of industries for their abilities of increasing the flexibility to meet a high variety of customer demands. Balancing assembly lines is a vital design issue for industries. However, the mixed-model two-sided assembly line balancing (MTALB) problem is NP-hard and difficult to solve in a reasonable computational time. So it is necessary for researchers to find some efficient approaches to address this problem. Honey bee mating optimization (HBMO) algorithm is a population-based algorithm inspired by the mating process in the real colony and has been applied to solve many combinatorial optimization problems successfully. In this paper, a hybrid HBMO algorithm is presented to solve the MTALB problem with the objective of minimizing the number of mated-stations and total number of stations for a given cycle time. Compared with the conventional HBMO algorithm, the proposed algorithm employs the simulated annealing (SA) algorithm with three different neighborhood structures as workers to improve broods, which could achieve a good balance between intensification and diversification during the search. In addition, a new encoding and decoding scheme, including the adjustment of the final mated-station, is devised to fit the MTALB problem. The proposed algorithm is tested on several sets of instances and compared with Mixed Integer Programming (MIP) and SA. The superior results of these instances validate the effectiveness of the proposed algorithm.","Title: An effective hybrid teaching-learning-based optimization algorithm for permutation flow shop scheduling problem.\nYear: 2014\n\nAbstract: •A teaching–learning-based optimization is proposed for flow shop problem.•A variable neighborhood search is proposed for fast solution improvement.•A simulated annealing is adopted as the local search method of VNS.•For the DMU problems, some new upper bounds have been obtained.","Title: A new methodology for multi-objective multidisciplinary design optimization problems based on game theory\nYear: 2015\n\nAbstract: We propose a new method based on gene expression programming and Nash equilibrium.The solutions are better than some solutions of other methods.The new method can obtain a better Nash solution with more accurate approximation. The design of engineering systems often involves multiple disciplines and competing objectives, which requires coordination, information exchange and share amongst the disciplines. However, in practical design environments, designers have to make decisions in isolation due to organization barriers, time schedules and geographical constraints. This paper will propose a new approach for the multi-objective multidisciplinary design optimization (MDO) problems in non-cooperative environments based on gene expression programming (GEP) and Nash equilibrium in the game theory. In this approach, the GEP method is used as a surrogate to construct the approximate rational reaction sets (RRSs) in the Nash model. The effectiveness of the proposed method is demonstrated by the design of a thin-walled pressure vessel and the hull form parameter design of a small waterplane area twin hull (SWATH) ship. The results show that this approach can fully explore and provide the explicit functional relationship between the strategy of an isolated player and the control variables of the other players, thus able to obtain a better Nash equilibrium solution.","Title: An adaptive global variable fidelity metamodeling strategy using a support vector regression based scaling function.\nYear: 2015\n\nAbstract: •We propose a difference adaptive decreasing variable-fidelity metamodeling approach.•SVR is adopted to map the difference between high-fidelity and low-fidelity models.•The presented approach can utilize the already-acquired information during modeling.•Effectiveness of DAD-VFM is demonstrated via several numerical and engineering cases.","Title: Optimization of laser welding process parameters of stainless steel 316L using FEM, Kriging and NSGA-II.\nYear: 2016\n\nAbstract: Multi-objective laser welding process parameters optimization approach is proposed.The effects of process parameters on bead profile in light of Kriging are analyzed.Experiment results show the efficiency of the proposed approach. Laser welding process parameters have significant effects on the welding bead profile and quality of the welding joint. This paper proposes an integration method of process parameters optimization using finite element method (FEM), Kriging metamodels and nondominated sorting genetic algorithm II (NSGA-II) in laser welding for stainless steel 316L. The process parameters in this study are laser power (LP), welding speed (WS) and laser focal position (LF). Firstly, a three-dimensional thermal finite element model is developed to obtain the simulated results of bead width (BW) and depth of penetration (DP). Then, Kriging metamodels are constructed to reflect the relationship between input process parameters and output responses. Finally, NSGA-II is used to search for multi-objective Pareto optimal solutions. In addition, the main effects and contribution rates of multiple process parameters on welding bead profile are analyzed. The results of verification experiments indicate that the optimal process parameters are effective and reliable for producing expected welding bead profile.","Title: An active learning metamodeling approach by sequentially exploiting difference information from variable-fidelity models.\nYear: 2016\n\nAbstract: We propose an active learning variable-fidelity metamodeling approach (AL-VFM).Information from high-fidelity and low-fidelity models is integrated in AL-VFM.An active learning strategy is introduced to use the already-acquired information.Numerical and engineering cases verify the applicability of the proposed approach. Complex system engineering design optimization based on simulation is a very time-consuming, even computationally prohibitive process. To relieve the computational burden, metamodels are commonly used to replace the computation-intensive simulations. In this paper, an active learning variable fidelity (VF) metamodeling approach (AL-VFM) is proposed for the purpose of integrating information from both low-fidelity (LF) and high-fidelity (HF) models. In AL-VFM, Kriging metamodel is adopted to map the difference between the HF and LF models aiming to approach the HF model on the entire domain. Besides, a general active learning strategy is introduced in AL-VFM to make full use of the already-acquired information to guide the VF metamodeling. The already-acquired information represents the location of regions where the differences between the HF and LF models are multi-model, non-smooth and have abrupt changes. Several numerical and engineering cases with different degrees of difficulty verify the applicability of the proposed VF metamodeling approach.","Title: An active learning radial basis function modeling method based on self-organization maps for simulation-based design problems.\nYear: 2017\n\nAbstract: The radial basis function has been widely used in constructing metamodels as response surfaces. Yet, it often faces the challenge of accuracy if a sequential sampling strategy is used to insert samples sequentially and refine the models, especially under the constraint of computational resources. In this paper, a sensitive region pursuing based active learning radial basis function (SRP-ALRBF) metamodeling approach is proposed to sequentially exploit the already-acquired knowledge in the modeling process for obtaining a desirable estimation of the relationship between the input design variables and the output response. In this method, the leave-one-out (LOO) errors of each sample point are taken to identify the boundaries of sensitive regions. According to the obtained LOO information, the original design space is divided into some subspaces by adopting the self-organization maps (SOMs). The boundary of the most sensitive region, where the output response is multi-modal or non-smooth with abrupt changes, is determined by the topological graph generated by cluster analysis in SOMs. In the most sensitive region, infill sample point searching is performed based on an optimization formulation. Ten numerical examples are used to compare the proposed SRP-ALRBF with four existing active learning RBF metamodeling approaches. Results show the advantage of the proposed SRP-ALRBF approach in both prediction accuracy and robustness. It is also applied to three engineering cases to illustrate its ability to support complex engineering design.","Title: A variable fidelity information fusion method based on radial basis function.\nYear: 2017\n\nAbstract: A variable-fidelity information fusion approach based on RBF is proposed.The low-fidelity output is taken as a prior-knowledge of the studied system.Cases study show the applicability and efficiency of the proposed approaches. Radial basis function (RBF) model has been widely used in complex engineering design process to replace the computational-intensive simulation models. This paper proposes a variable-fidelity metamodeling (VFM) approach based on RBF, in which different levels fidelity information can be integrated and fully exploited. In the proposed VFM approach, a RBF metamodel is constructed for the low-fidelity (LF) model as a start. Then by taking the constructed LF metamodel as a prior-knowledge and mapping the output space of the LF metamodel to that of the studied high-fidelity (HF) model, a variable fidelity (VF) metamodel is created to approximate the relationships between the design variables and corresponding output responses. A numerical illustrative example is adopted to make a detailed comparison between the VFM approach developed in this research and three existing scaling function based VFM approaches, considering different sample sizes and sample noises. Results illustrate that the proposed VFM approach outperforms the scaling function based VFM approaches both in global and local accuracy. Then the proposed VFM approach is applied to two engineering problems, modeling aerodynamic data for a three-dimensional aircraft and the prediction of weld bead profile in laser welding, to illustrate its ability in support of complex engineering design.","Title: A sequential multi-fidelity metamodeling approach for data regression.\nYear: 2017\n\nAbstract: •A sequential multi-fidelity (SMF) metamodeling approach is proposed.•Different fidelity information can be incorporated in SMF metamodeling process.•Where to allocate low-fidelity (LF) and high-fidelity (HF) sample points is solved.•How to split the total computational budget between LF and HF models is addressed.•The effectiveness and merits of the proposed SMF method are tested on three cases.","Title: Multiobjective Program and Hybrid Imperialist Competitive Algorithm for the Mixed-Model Two-Sided Assembly Lines Subject to Multiple Constraints.\nYear: 2018\n\nAbstract: A mixed-model two-sided assembly line is a manufacturing system designed for the production of large-sized products. In order to describe the actual condition, this paper presents a novel multiobjective programming model for balancing a mixed-model two-sided assembly line subject to multiple constraints, in which, additional constraints including zoning, synchronous, and positional constraints are considered besides the traditional constraints, e.g., the precedence constraint. Two objectives are simultaneously to be optimized, one is to minimize the combination of the weighted line efficiency and the weighted smoothness index, and the other is to minimize the weighted total relevant costs per unit of a product. A novel multiobjective hybrid imperialist competitive algorithm (MOHICA) is proposed to solve this problem. In the presented MOHICA, the sigma method is employed to quantify every individual, a novel merging method is introduced to reserve better individuals into the evolutionary population, and late acceptance hill-climbing (LAHC) algorithm is presented as a local search algorithm to achieve accurate balance between intensification and diversification. The experimental results on the selected benchmark instances and a practical case show that the proposed multiobjective algorithm outperforms nondominated sorting genetic algorithm (NSGA)-II, multiobjective improved teaching-learning-based optimization, and NSGA-III existing in the literature.","Title: A space mapping method based on Gaussian process model for variable fidelity metamodeling.\nYear: 2018\n\nAbstract: •A space mapping based variable-fidelity metamodeling approach is developed.•The low-fidelity information is taken as a prior-knowledge of the studied system.•A mathematic example is used for step-by-step illustration.•The proposed approach is applied to two real-life cases.","Title: An on-line variable fidelity metamodel assisted Multi-objective Genetic Algorithm for engineering design optimization.\nYear: 2018\n\nAbstract: •An on-line variable-fidelity metamodel (VFM) assisted Multi-Objective Genetic Algorithms (OLVFM-MOGA) approach is proposed to ease the computational burden.•A novel model management strategy is adopted to update the VFM to improve optimization quality.•Metamodel uncertainty and computational cost of different fidelity models are considered in proposed approach.•Cases study shows the applicability and efficiency of the proposed approaches.","Title: An adaptive sampling strategy for Kriging metamodel based on Delaunay triangulation and TOPSIS.\nYear: 2018\n\nAbstract: Metamodels have been widely used in engineering design and optimization. Sampling method plays an important role in the constructing of metamodels. This paper proposes an adaptive sampling strategy for Kriging metamodel based on Delaunay triangulation and TOPSIS (KMDT). In the proposed KMDT, Delaunay triangulation is employed to partition the design space according to current sample points. The area of each partitioned triangle is used to indicate the degree of dispersion of sample points, and the prediction error of Kriging metamodel at each triangle’s centroid is used to represent the local error of each triangle region. By calculating the weight of the area and prediction error for each triangle region using the entropy method and TOPSIS, the degree of dispersion of sample points and local errors of metamodel are taken into consideration to make a trade-off between global exploration and local exploitation during the sequential sampling process. As a demonstration, the proposed approach is compared to other three sampling methods using several numerical cases and the modeling of the aerodynamic coefficient for a three-dimensional aircraft. The result reveals that the proposed approach provides more accurate metamodel at the same simulation cost, which is very important in metamodel-based engineering design problems.","Title: Multi-sensor information fusion for remaining useful life prediction of machining tools by adaptive network based fuzzy inference system.\nYear: 2018\n\nAbstract: •A multi-sensor information fusion system for online RUL prediction of machining tools is designed.•An improved EEMD method is proposed for attenuating undesired signals and solving mode mixing problem.•Statistics features are respectively extracted by segmentation in time domain and frequency domain.•Optimal features are selected based on essential characteristics of these extracted features, which include correlation, monotonicity, and autocorrelation.•An ANFIS architecture with subtraction clustering and fuzzy space partition is designed for the feature fusion and online RUL prediction.","Title: Degradation Data-Driven Time-To-Failure Prognostics Approach for Rolling Element Bearings in Electrical Machines.\nYear: 2019\n\nAbstract: Time-to-failure (TTF) prognostic plays a crucial role in predicting remaining lifetime of electrical machines for improving machinery health management. This paper presents a novel three-step degradation data-driven TTF prognostics approach for rolling element bearings (REBs) in electrical machines. In the degradation feature extraction step, multiple degradation features, including statistical fe...","Title: Machine Health Monitoring Using Adaptive Kernel Spectral Clustering and Deep Long Short-Term Memory Recurrent Neural Networks.\nYear: 2019\n\nAbstract: Machine health monitoring is of great importance in industrial informatics field. Recently, deep learning methods applied to machine health monitoring have been proven effective. However, the existing methods face enormous difficulties in extracting heterogeneous features indicating the variation until failure and revealing the inherent high-dimensional features of massive signals, which affect th...","Title: Design A Degradation Condition Monitoring System Scheme For Rolling Bearing Using Emd And Pca\nYear: 2017\n\nAbstract: Purpose - Rolling bearings based on rotating machinery are one of the most widely used in industrial applications because of their low cost, high performance and robustness. The purpose of this paper is to describe how to identify degradation condition of rolling bearing and predict its fault time in big data environment in order to achieve zero downtime performance and preventive maintenance for the rolling bearing.Design/methodology/approach - The degradation characteristic parameters of rolling bearings including intrinsic mode energy and failure frequency were, respectively, extracted from the pre-processed original vibration signals using EMD and Hilbert transform. Then, Spearman's rank correlation coefficient and PCA were used to obtain the health index of the rolling bearing so as to detect the appearance of degradations. Furthermore, the degradation condition of the rolling bearings might be identified through implementing the monotonicity analysis, robustness analysis and degradation analysis of the health index.Findings - The effectiveness of the proposed method is verified by a case study. The result shows that the proposed method can be applied to monitor the degradation condition of the rolling bearings in industrial application.Research limitations/implications - Further experiment remains to be done so as to validate the effectiveness of the proposed method using Apache Hadoop when massive sensor data are available.Practical implications - The paper proposes a methodology for rolling bearing condition monitoring representing the steps that need to be followed. Real-time sensor data are utilized to find the degradation characteristics.Originality/value - The result of the work presented in this paper form the basis for the software development and implementation of condition monitoring system for rolling bearings based on Hadoop.","Title: A multi-fidelity information fusion metamodeling assisted laser beam welding process parameter optimization approach.\nYear: 2017\n\nAbstract: A multi-fidelity (MF) metamodel assisted welding parameter optimization is proposed.A 3D thermal finite element model is developed as a low-fidelity model.A laser welding physical experiment is taken as the high-fidelity model.The MF metamodel is built based on two different levels fidelity information fusion.Verification experiments illustrated the reliability of the final optima. Selecting reasonable laser beam welding (LBW) process parameters is very helpful for obtaining a good welding bead profile and hence a high quality of the welding joint. Existing process parameter optimization approaches for LBW either based on cost-expensive physical experiments or low-fidelity (LF) computer simulations. This paper proposes a multi-fidelity (MF) metamodel based LBW process parameter optimization approach, in which different levels fidelity information, both from LF computer simulations and high-fidelity (HF) physical experiments can be integrated and fully exploited. In the proposed approach, a three-dimensional thermal finite element model is developed as the LF model, which is fitted with a LF metamodel firstly. Then, by taking the LF metamodel as a base model and scaling it using the HF physical experiments, a MF metamodel is constructed to approximate the relationships between the LBW process parameters and the bead profile. Two metrics are adopted to compare the prediction accuracy of the MF metamodel with the single-fidelity metamodels solely constructed with physical experiments or computer simulations. Results illustrate that the MF metamodel outperforms the single-fidelity metamodels both in global and local accuracy. Finally, the fast elitist non-dominated sorting genetic algorithm (NSGA-II) is used to facilitate LBW process parameter space exploration and multi-objective Pareto optima search. LBW verification experiments verify the effectiveness and reliability of the obtained optimal process parameters.","Title: Mathematical Modelling And Optimisation Of Energy-Conscious Hybrid Flow Shop Scheduling Problem With Unrelated Parallel Machines\nYear: 2019\n\nAbstract: This paper investigates an energy-conscious hybrid flow shop scheduling problem with unrelated parallel machines (HFSP-UPM) with the energy-saving strategy of turning off and on. We first analyse the energy consumption of HFSP-UPM and formulate five mixed integer linear programming (MILP) models based on two different modelling ideas namely idle time and idle energy. All the models are compared both in size and computational complexities. The results show that MILP models based on different modelling ideas vary dramatically in both size and computational complexities. HFSP-UPM is NP-Hard, thus, an improved genetic algorithm (IGA) is proposed. Specifically, a new energy-conscious decoding method is designed in IGA. To evaluate the proposed IGA, comparative experiments of different-sized instances are conducted. The results demonstrate that the IGA is more effective than the genetic algorithm (GA), simulating annealing algorithm (SA) and migrating birds optimisation algorithm (MBO). Compared with the best MILP model, the IGA can get the solution that is close to an optimal solution with the gap of no more than 2.17% for small-scale instances. For large-scale instances, the IGA can get a better solution than the best MILP model within no more than 10% of the running time of the best MILP model.","Title: Multisensory Data-Driven Health Degradation Monitoring of Machining Tools by Generalized Multiclass Support Vector Machine.\nYear: 2019\n\nAbstract: Health degradation monitoring of machining tools is of great importance in industrial application field. In this paper, a novel multisensory data-driven health degradation monitoring system schema for the machining tools is proposed by using a generalized multiclass support vector machine (GenSVM). In this schema, multidimensional feature extraction is implemented in the time domain, frequency domain, and time-frequency domain based on the time domain statistical analysis, power spectrum analysis, and complete ensemble empirical mode decomposition with adaptive noise, respectively. On the basis, effective features that are strongly associated with the degradation process are picked out using a Pearson correlation coefficient. Meanwhile, a new and flexible GenSVM model is constructed to identify the health state of machining tools, which integrates a simplex encoding and iterative majorization optimization algorithm. A practical application case study is implemented to verify the effectiveness of the proposed method. The results show the superior performance of the proposed method compared with other standard methods.","Title: Sensor Data-Driven Bearing Fault Diagnosis Based on Deep Convolutional Neural Networks and S-Transform.\nYear: 2019\n\nAbstract: Accurate and timely bearing fault diagnosis is crucial to decrease the probability of unexpected failures of rotating machinery and improve the efficiency of its scheduled maintenance. Since convolutional neural networks (CNN) have poor feature extraction capability for sensor data with 1D format, CNN combined with signal processing algorithm is often adopted for fault diagnosis. This increases manual conversion work and expertise dependence while reducing the feasibility and robustness of the corresponding fault diagnosis method. In this paper, a novel sensor data-driven fault diagnosis method is proposed by fusing S-transform (ST) algorithm and CNN, namely ST-CNN. First of all, a ST layer is designed based on S-transform algorithm. In the ST layer, sensor data is automatically converted into 2D time-frequency matrix without manual conversion work. Then, a new ST-CNN model is constructed, and the time-frequency coefficient matrixes are inputted into the constructed ST-CNN model. After the training process of the ST-CNN model is completed, the classification layer such as softmax performs the fault diagnosis. Finally, the diagnosis performance of the proposed method is evaluated by using two public available datasets of bearings. The experimental results show that the proposed method performs the higher and more robust diagnosis performance than other existing methods."],"string":"[\n \"Title: Integration of process planning and scheduling-A modified genetic algorithm-based approach\\nYear: 2009\\n\\nAbstract: Traditionally, process planning and scheduling for parts were carried out in a sequential way, where scheduling was done after process plans had been generated. Considering the fact that the two functions are usually complementary, it is necessary to integrate them more tightly so that performance of a manufacturing system can be improved greatly. In this paper, a new integration model and a modified genetic algorithm-based approach have been developed to facilitate the integration and optimization of the two functions. In the model, process planning and scheduling functions are carried out simultaneously. In order to improve the optimized performance of the modified genetic algorithm-based approach, more efficient genetic representations and operator schemes have been developed. Experimental studies have been conducted and the comparisons have been made between this approach and others to indicate the superiority and adaptability of this method. The experimental results show that the proposed approach is a promising and very effective method for the integration of process planning and scheduling.\",\n \"Title: Constraint-based Collaborative Design\\nYear: 2006\\n\\nAbstract: Collaborative design can be characterized by different level constraints that describe basic elements of design process such as human, information and resource. In design, satisfied solutions to constraints must occur to arrive at a final design result. Few collaborative design systems exist for adequately representing constraints, and formally combining them from different disciplines. The main contribution of this paper is to introduce a methodology for analyzing the constraints in collaborative design. A hierarchy of fuzzy constraint networks is presented along with a methodology for creating interlinks between different levels of the hierarchy. The solution methodology is illustrated with an example. The paper concludes with directing attention to current challenges and recommendations for research\",\n \"Title: A Reduction Algorithm Based on the Degree of Attribute Discernibility\\nYear: 2006\\n\\nAbstract: This paper studies the problem of attribute discernibility reduction and introduces some new concepts to Rough Set theory, such as Secondary Core, Regeneration Matrix and the degree of attribute discernibility. An attribute reduction algorithm has been proposed based on the concept of highest discernibility. The efficacy of this algorithm has been verified by practical application in a diagnostic system of mechanical loader, which displays notably decrease in information gathering requirement and lowers down the overall cost without any loss of accuracy.\",\n \"Title: An effective hybrid particle swarm optimization algorithm for multi-objective flexible job-shop scheduling problem\\nYear: 2009\\n\\nAbstract: Flexible job-shop scheduling problem (FJSP) is an extension of the classical job-shop scheduling problem. Although the traditional optimization algorithms could obtain preferable results in solving the mono-objective FJSP. However, they are very difficult to solve multi-objective FJSP very well. In this paper, a particle swarm optimization (PSO) algorithm and a tabu search (TS) algorithm are combined to solve the multi-objective FJSP with several conflicting and incommensurable objectives. PSO which integrates local search and global search scheme possesses high search efficiency. And, TS is a meta-heuristic which is designed for finding a near optimal solution of combinatorial optimization problems. Through reasonably hybridizing the two optimization algorithms, an effective hybrid approach for the multi-objective FJSP has been proposed. The computational results have proved that the proposed hybrid algorithm is an efficient and effective approach to solve the multi-objective FJSP, especially for the problems on a large scale.\",\n \"Title: Fuzzy multiple attributive group decision-making for conflict resolution in collaborative design\\nYear: 2006\\n\\nAbstract: Most conflicts in collaborative design are categorized as the problem of fuzzy multiple attributive group decision-making (FMAGDM). Both fuzzy assessments and the aggregation of multiple experts' opinions should be considered in the conflict resolution process. This paper presents a new approach for the problem, where cooperation degree (CD) and reliability degree (RD) are introduced for aggregating the vague experts' opinions. Furthermore, a fuzzy multiple attributive group decision-making expert system (FMAGDMES) is proposed to provide an interactive way to solve conflicts in collaborative environment. It is an intelligent integrated system because it combines fuzzy set theory with the method of group opinion aggregation. The vehicle performance evaluation as a real case is used to validate the efficiency of the proposed expert system, which is implemented by using c++.\",\n \"Title: Multi-agent based integration of process planning and scheduling\\nYear: 2009\\n\\nAbstract: Traditionally, process planning and scheduling were performed sequentially, where scheduling was done after process plans had been generated. Considering the fact that the two functions are usually complementary, it is necessary to integrate them more tightly so that the performance of a manufacturing system can be improved greatly. In this paper, a Multi-agent-based approach has been developed to facilitate the integration of the two functions. In the approach, the two functions are carried out simultaneously, and an optimization agent based on an evolutionary algorithm is used to manage the interactions and communications between agents to enable proper decisions to be made. To verify the feasibility and performance of the proposed approach, an experimental study has been conducted and comparisons have been made between this approach and some previous works. The experimental results show the proposed approach has achieved significant improvement.\",\n \"Title: Development of a design structure matrix partitioning method towards effective design collaboration.\\nYear: 2012\\n\\nAbstract: The difficulties in design collaboration stem from the managerial complexity in terms of the interactions and interdependencies among the respective development activities. This paper introduces a simple structural partitioning algorithm of design structure matrix, basing on dependency relationships among tasks via tracing the input tasks chain. The algorithm is composed of four modules, which are used to organise and transform design tasks into input model, cycle model, group model and execution ordering model correspondingly. Cycle matrix is created to partition the task set into individual groups that are with different interdependency levels. Coupled and unordered individual task set could be converted into uncoupled, ordered task clusters. The illustrative case studies on automotive industry has verified the efficiency of the proposed algorithm, which could partition the development processes into different execution clusters to improve the concurrence and collaboration of product development tasks. Copyright © 2012 Inderscience Enterprises Ltd.\",\n \"Title: A Web services based distributed multidisciplinary design optimization framework to ship design\\nYear: 2011\\n\\nAbstract: Ship design is a complex process, which contains many coupled disciplines and needs the collaboration among geographical distributed design resources. Multidisciplinary Design Optimization (MDO) provides a promising way to ship design compared to traditional spiral design approach. As the important enabling tool, MDO framework is vital to the successful implementation of MDO problems. In this paper, at the base of surveying the state of the art of some notable MDO frameworks, a Web services and Isight based distributed ship MDO framework is proposed, which provides an easy way to integrate distributed design, analysis, optimization services, namely various tools and programs, to jointly implement ship design. At the same time, according to the requirements of ship design, some new and extended function modules are added, which incorporates a number of existing technologies such as workflow, component technology.\",\n \"Title: Mathematical modeling and evolutionary algorithm-based approach for integrated process planning and scheduling\\nYear: 2010\\n\\nAbstract: Traditionally, process planning and scheduling were performed sequentially, where scheduling was implemented after process plans had been generated. Considering their complementarity, it is necessary to integrate these two functions more tightly to improve the performance of a manufacturing system greatly. In this paper, a mathematical model of integrated process planning and scheduling has been formulated. And, an evolutionary algorithm-based approach has been developed to facilitate the integration and optimization of these two functions. To improve the optimized performance of the approach, efficient genetic representation and operator schemes have been developed. To verify the feasibility and performance of the proposed approach, experimental studies have been conducted and comparisons have been made between this approach and some previous works. The experimental results show that the integrated process planning and scheduling is necessary and the proposed approach has achieved significant improvement.\",\n \"Title: A PSO-FUZZY Group decision-making Support System in vehicle performance evaluation\\nYear: 2010\\n\\nAbstract: Group decision-making (GD) is a fuzzy problem with high complexity and difficult to be handled. Usually the rule-based Group decision-making Support System (GDSS) is used to solve GD problem. But the definition of fuzzy rules and membership functions in GDSS are generally affected by subjective decision. So the rationality of GDSS is difficult to be judged. In this paper, the particle swarm optimization (PSO) algorithm is introduced to improve the fuzzy rule base through optimize the position and shape of fuzzy rule set and weights of rules. A PSO-fuzzy GDSS is set up and used to a real application of vehicle performance evaluation. According to the contrast of three methods: Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), non-weighted fuzzy rule base, and PSO-fuzzy GDSS, the result shows that weighted fuzzy rule base after PSO optimized is better than non-weighted fuzzy rule base, and the evaluation values of PSO-fuzzy GDSS are very close to the TOPSIS. Therefore, the PSO-fuzzy GDSS is an efficient method for vehicle performance evaluation and can be applied to more domains.\",\n \"Title: Integration of variable precision rough set and fuzzy clustering: an application to knowledge acquisition for manufacturing process planning\\nYear: 2005\\n\\nAbstract: Knowledge acquisition plays a significant role in the knowledge-based intelligent process planning system, but there remains a difficult issue. In manufacturing process planning, experts often make decisions based on different decision thresholds under uncertainty. Knowledge acquisition has been inclined towards a more complex but more necessary strategy to obtain such thresholds, including confidence, rule strength and decision precision. In this paper, a novel approach to integrating fuzzy clustering and VPRS (variable precision rough set) is proposed. As compared to the conventional fuzzy decision techniques and entropy-based analysis method, it can discover association rules more effectively and practically in process planning with such thresholds. Finally, the proposed approach is validated by the illustrative complexity analysis of manufacturing parts, and the analysis results of the preliminary tests are also reported.\",\n \"Title: HUST-CDMS: A Test-bed for Collaborative Design and Manufacturing\\nYear: 2006\\n\\nAbstract: A test-bed (HUST-CDMS) for collaborative product design and manufacturing is described in this paper. This test-bed is constructed by using a CORBA and MAS based system architecture, where diverse and heterogeneous design and manufacturing resources are MAS-based agentified and CORBA-based encapsulated as resource agents and subsequently integrated in the system. These resource agents communicate and interact with each other by means of agent interoperation and human-machine interaction to achieve a collaborative design and manufacturing environment, aiming at reducing the lead time and costs\",\n \"Title: An agent-based approach for integrated process planning and scheduling\\nYear: 2010\\n\\nAbstract: Traditionally, process planning and scheduling were performed sequentially, where scheduling was done after process plans had been generated. Considering the fact that these two functions are usually complementary, it is necessary to integrate them more tightly so that the performance of a manufacturing system can be improved greatly. In this paper, an agent-based approach has been developed to facilitate the integration of these two functions. In the approach, the two functions are carried out simultaneously, and an optimization agent based on an evolutionary algorithm is used to manage the interactions and communications between agents to enable proper decisions to be made. To verify the feasibility and performance of the proposed approach, experimental studies have been conducted and comparisons have been made between this approach and some previous works. The experimental results show the proposed approach has achieved significant improvement.\",\n \"Title: Relay Node Deployment Based Small World Effect in Hierarchical Industrial Wireless Sensor Networks\\nYear: 2013\\n\\nAbstract: The industrial wireless sensor networks (IWSNs) brings several advantages over traditional wired industrial monitoring and control systems. The communication reliability of IWSNs has to be guaranteed as the real-time field data need to be transmitted to the control system. The specific requirements of IWSNs have brought challenges to the deployment strategy of sensors in industrial environments. Obviously the network architecture has a significant influence on the performance of IWSNs. Therefore, in this paper, we place three types of nodes in a manufacturing shop to monitor equipment situation, production status and environment. We construct an IWSN with small world characteristics through the random additions of efficient relay nodes and short-cuts at a certain probability. The sensor data will be transmitted in multi-hop to the server quickly and exactly through the small world IWSN. In addition, the proposed deployment strategy will ensure balanced energy-usage among the nodes in the network. Simulation results show that the built network topology possesses the property of rapid transmission to reduce the transmission relay drastically and has good robustness. Compared to the flat single-tier network structure of homogeneous sensor nodes, the small world networks utilizing heterogeneous elements will be preferred in IWSNs.\",\n \"Title: A Web services and process-view combined approach for process management of collaborative product development\\nYear: 2009\\n\\nAbstract: Collaborative Product Development (CPD) across enterprises has been recognized as an effective strategy to connect multi-enterprise wide project teams to develop more competitive products. Process management is vital to the successful implementation of CPD in a multi-enterprise environment. In this paper, a novel Web Services (WSs) and process-view combined approach has been developed to manage the dynamic and distributed process of CPD to enhance the workflow interoperability among heterogeneous Workflow Management Systems (WMSs) of enterprises. Meanwhile, a hybrid P2P based WMSs framework has been built to provide an open and scalable architecture to deploy inter-enterprises collaboration. A software prototype system has been implemented using the open JXTA platform, and the collaborative development of a motorcycle has been used as a test case to validate the proposed approach and the prototype system.\",\n \"Title: A product module identification approach based on axiomatic design and design structure matrix.\\nYear: 2012\\n\\nAbstract: In terms of creating customized products rapidly, modularity is deemed to be an effective developmental strategy for handling product variety and intricacy. In order to develop reasonable modular product architecture with physically detachable modules, a new systematic and structured approach for product modularization based on axiomatic design and design structure matrix is proposed. The product is decomposed hierarchically into its functional, physical, and process domains using axiomatic design method. After transformation from design matrix to design structure matrix, the pertinence design structure matrices of design parameters describing function, structure, and manufacturing process are constructed. Besides, a manufacturing process similarity matrix of design parameters is established. Finally, a genetic algorithm combined with the minimal description length is employed to realize the modularization optimization after integration of the above matrices. To illustrate the effectiveness of the proposed methodology, an indoor air conditioner unit is presented as a demonstrative example.\",\n \"Title: Analytical Target Cascading Based on Physical Programming\\nYear: 2010\\n\\nAbstract: Analytical Target Cascading (ATC) is a product development tool that computes component design specifications so that the final system design is consistent and meets design targets. It is a promising methodology for decomposition of complex system design and optimization. However, ATC has some shortcomings inherently. In this paper, after analyzing the theory and model of ATC, a more promising method entitled Analytical Target Cascading Based on Physical Programming (ATC-PP) is proposed. This new approach is intended to substantially place the design process into a more flexible and practical framework by adding the advantages of Physical Programming (PP) into ATC. And the preference function which is proposed in PP is used to definite the deviation between response and linking variables in ATC in the new method. It can completely eliminate the need for assigning weight coefficient, which is the object of the typical computational bottleneck in large design optimization problems. And it could also give the designers' preferences in practical design. Finally, the validity of ATC-PP is approved by studying an anchor design problem.\",\n \"Title: A Vr-Based Simulation System For Glass Pressing\\nYear: 2008\\n\\nAbstract: The integration with virtual reality is a new boost to CAD and CAE. This paper presents a research effort aimed at creating a desktop-based, low-cost and independent VR-based simulation system for glass pressing, which integrates the forming process simulation and mold motion simulation. The skeletal animation technique is employed for Motion Simulation of the mold The stereoscopic view of the virtual system is achieved by Crystal Eyes shutter glasses, with C++ language and OpenGL support library selected as the development tool. With the stereoscopic display of the mold design, pressing motion and numerical CAE results, the system enables engineers to gain a cohesive view of mold structure, assembly issues, and possible forming faults. it can also support training of students and engineers to acquire the theoretical know-how, practical skills, and the problem troubleshooting techniques of glass pressing. (C) 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 315-320. 2008: Published online in Wiley InterScience (www.interscience.wiley.com): DOI 10.1002/cae.20216\",\n \"Title: A process-view approach for cross-organizational workflows management\\nYear: 2010\\n\\nAbstract: Workflow management for cross-organizational business processes presents a significant challenge recently. The development and implementation of new methodologies and technologies are imperative to tackle this challenge. The process-view approach provides a promising way to facilitate cross-organizational workflows management, especially when it is combined with powerful workflow modeling methods. With the assumption that workflow modeling methods in cooperative organizations are interoperable, a process-view and timed colored Petri net (TCPN) combined approach is proposed to manage cross-organizational workflows, including the formal definition, the mapping from TCPN workflow models to process-view workflow models in which the aspects of control flow and data flow are considered together, and the collaborative execution mechanisms of cross-organizational workflow instances. A hybrid P2P based decentralized workflow management system (WMS) combined with the process-view approach is proposed and built, which is placed on the top of the open JXTA platform and provides a flexible and scalable architecture for cross-organizational workflows management. At last, the cross-organizational workflows management for the distributed development of a circular saw has been used as a test case for system validation.\",\n \"Title: A new approach for predicting and collaborative evaluating the cutting force in face milling based on gene expression programming\\nYear: 2013\\n\\nAbstract: Cutting force is one of the fundamental elements that can provide valuable insight in the investigation of cutter breakage, tool wear, machine tool chatter, and surface finish in face milling. Analyzing the relationship between process factors and cutting force is helpful to set the process parameters of the future cutting operation and further improve production quality and efficiency. Since cutting force is impacted by the inherent uncertainties in the machining process, how to predict the cutting force presents a significant challenge. In the meantime, face milling is a complex process involving multiple experts with different domain knowledge, collaborative evaluation of the cutting force model should be conducted to effectively evaluate the constructed predictive model. Gene Expression Programming (GEP) combines the advantages of the Genetic Algorithm (GA) and Genetic Programming (GP), and has been successfully applied in function mining and formula finding. In this paper, a new approach to predict the face milling cutting force based on GEP is proposed. At the basis of defining a GEP environment for the cutting force prediction, an explicit predictive model has been constructed. To verify the effectiveness of the proposed approach, a case study has been conducted. The comparisons between the proposed approach and some previous works show that the constructed model fits very well with the experimental data and can predict the cutting force with a high accuracy. Moreover, in order to better apply the constructed predictive models in actual face milling process, a collaborative model evaluation method is proposed to provide a distributed environment for geographical distributed experts to evaluate the constructed predictive model collaboratively, and four kinds of collaboration mode are discussed.\",\n \"Title: Scheduling Mixed-Model Assembly Lines with Cost Objectives by a Hybrid Algorithm\\nYear: 2008\\n\\nAbstract: This paper is concerned about how to optimize the input sequence for a mixed-model assembly line (MMAL) with limited intermediate buffers. Three optimization objectives are considered simultaneously: minimizing the total production rate variation, the total setup, and the total assembly cost. The mathematical model is presented by incorporating the three objectives. Since the problem is NP-hard, a hybrid algorithm based on genetic algorithm (GA) and simulated annealing (SA), is proposed for solving the model. The performance of the proposed algorithm is compared with a genetic algorithm for different-sized sequencing problems in MMALs that consist of different number of machines and different production plans. The computational results show that the proposed hybrid algorithm finds solutions with better quality and often needs a smaller number of generations to converge to a final stable state, especially in the case of large-sized problems.\",\n \"Title: A Genetic Algorithm for Integration of Process Planning and Scheduling Problem\\nYear: 2008\\n\\nAbstract: Traditionally, process planning and scheduling for parts are carried out in a sequential way, where scheduling is done after process plans have been generated. Considering the two functions are usually complementary, there is a great potential to integrate them more tightly so that greater performance and higher productivity of a manufacturing system can be achieved. In this paper, a genetic algorithm-based approach has been developed to facilitate the integration and optimization of these two functions. To improve the optimized performance of the genetic algorithm-based approach, efficient genetic representations and operator schemes have been developed. Experiment studies have been conducted. The experimental results show that the proposed approach is a promising and very effective method for the integration of process planning and scheduling.\",\n \"Title: On-Line Simulation for Shop Floor Control in Manufacturing Execution System\\nYear: 2008\\n\\nAbstract: This paper presents and discusses the structure and components of a novel on-line simulation system for real-time shop floor control in manufacturing execution system (MES). The framework of the simulation system is constructed in association with a MES. The on-line simulation system can collect data from physical shop floor and communicate with a scheduling controller through the MES. Furthermore, MES can provide much of the dynamic information required by the simulation model, and can also execute the shop floor control strategy which is solved by the simulation system. A multi-pass simulation method is introduced and applied to control the shop floor.\",\n \"Title: Reactive scheduling in a job shop where jobs arrive over time\\nYear: 2013\\n\\nAbstract: The paper considers the dynamic job shop scheduling problem (DJSSP) with job release dates which arises widely in practical production systems. The principle characteristic of DJSSP considered in the paper is that the jobs arrive continuously in time and the attributes of the jobs, such as the release dates, routings and processing times are not known in advance, whereas in the classical job shop scheduling problem (CJSSP), it is assumed that all jobs to be processed are available at the beginning of the scheduling process. Reactive scheduling approach is one of the effective approaches for DJSSP. In the paper, a heuristic is proposed to implement the reactive scheduling of the jobs in the dynamic production environment. The proposed heuristic decomposes the original scheduling problem into a number of sub problems. Each sub problem, in fact, is a dynamic single machine scheduling problem with job release dates. The scheduling technique applied in theproposed heuristic is priority scheduling, which determines the next state of the system based on priority values of certain system elements. The system elements are prioritized with the help of scheduling rules (SRs). An approach based on gene expression programming (GEP) is also proposed in the paper to construct efficient SRs for DJSSP. The rules constructed by GEP are evaluated in the comparison of the rules constructed by GP and several prominent human made rules selected from literatures on extensive problem sets with respect to various measures of performance.\",\n \"Title: Design and implementation of a process-oriented intelligent collaborative product design system\\nYear: 2004\\n\\nAbstract: With the competition between companies being fiercer and customers being more demanding, the efficiency of design decision-making must be improved to shorten the product design cycle. Intelligent collaborative product design is needed in the product design process. In this paper, based on the Analysis-Synthesis-Evaluation (ASE) design paradigm and the parameterization of product design, an agent that incorporates the working mechanism of expert systems is designed to assist a designer in his work. In line with the modularization of the product design, a module-based multi-agent system is developed and deployed according to the CORBA standards to facilitate the coordination among designers within the range of enterprises and even virtual enterprises. In the light of preliminary tests on the Internet, the agent and the agent system show some, advantages to increase the efficiency of the design coordination and decision-making in the product design process.\",\n \"Title: Social aspects of collaborative design\\nYear: 2008\\n\\nAbstract: Collaborative design is a complex process being carried out by distributed teams. Collaboration requires successful and efficient sharing of knowledge, negotiation, coordination and management of activities. In distributed environments, design members are moving to network forms through alliances and other collaborative relationships as a social network. This paper explores collaborative design process from a sociological viewpoint. A social factor-based architecture for collaborative design is investigated, with special attention given to patterns of social behavior and the organizations of those who participate in the design. Social factors thought to have played a role include perspectives, preference, attitudes, cognition, etc. The main contribution of this paper is to introduce a methodology for analyzing the social aspects of collaborative design. The paper concludes with directing attention to current challenges and recommendations for research.\",\n \"Title: Optimization of manufacturing systems using Genetic Search and Muti-resolution simulation.\\nYear: 2010\\n\\nAbstract: This paper presents a method for the optimization of manufacturing systems by using Genetic Search and Multi-level Modeling Multi-resolution Simulation. The method can realize genetic optimization for manufacturing systems by using multi-resolution simulation which is based on the multi-level modeling. This paper focuses on the design of the genetic optimization searching algorithm and the optimization of a complex manufacturing system, through the comprehensive use of relevant methods in order to optimize in parallel the target system's structure parameters and operational behaviors with a reasonable time-effectiveness performance. © 2010 IEEE.\",\n \"Title: An effective modified Particle Swarm Optimization algorithm for process planning\\nYear: 2010\\n\\nAbstract: In the modern manufacturing system, most jobs have a large number of flexible process plans. However, there is only one process plan can be selected for a job in the manufacturing process. Therefore, flexible process plans selection has become a crucial problem in a manufacturing environment. It is a combinatorial optimization problem to conduct operations selection and operations sequencing simultaneously with various constraints deriving from the practical workshop environment as well as the jobs to be processed. In this paper, a new method using a modified particle swarm optimization (PSO) algorithm is presented to optimize the process planning problem. To improve the optimization performance of the approach, efficient encoding and updating strategies have been developed. To verify the feasibility and performance of the proposed approach, a case study has been conducted. The results show that the proposed modified PSO algorithm can generate satisfactory solutions.\",\n \"Title: A prior-knowledge input LSSVR metamodeling method with tuning based on cellular particle swarm optimization for engineering design\\nYear: 2014\\n\\nAbstract: Engineering design is usually a daunting optimization task which often involving time-consuming, even computation-prohibitive process. To reduce the computational expense, metamodels are commonly used to replace the actual expensive simulations or experiments. In this paper, a new and efficient metamodeling method named prior-knowledge input least square support vector regression (PKI-LSSVR) is developed, in which samples from different levels of fidelity are incorporated to gain an accurate approximation with limited times of the high-fidelity (HF) expensive simulations. The low-fidelity (LF) output serves as a prior-knowledge of the real response function, and then is used as the input variables of least square support vector regression (LSSVR). When the corresponding HF response is gained, a function that maps the LF outputs to HF outputs is constructed via LSSVR. The predictive accuracy of LSSVR models is highly dependent on their learning parameters. Therefore, a novel optimization method, cellular particle swarm optimization (CPSO), is exploited to seek the optimal hyper-parameters for PKI-LSSVR in order to improve its generalization capability. To get a better optimization performance, a new neighborhood function is developed for CPSO where the global and local search is efficiently balanced by adaptively varied neighbor radius. Several numerical experiments and one engineering case verify the efficiency of the proposed PKI-LSSVR method. Sample quality merits including sample sizes and noise, and metamodel performance evaluation measures incorporating accuracy, robustness, and efficiency are considered.\",\n \"Title: A cost-based selective maintenance decision-making method for machining line\\nYear: 2011\\n\\nAbstract: Machine line is a type of manufacturing system in which machines are connected in series or in parallel. It is significant to ensure the reliability as well as to reduce the total cost of maintenance and failure losses in the maintenance programs of such systems. Cost-based selective maintenance decision-making, which is the best method for a selected group of machines in machine line is presented under limited maintenance durations. Fault losses and maintenance costs of a single machine under different maintenance actions i.e. minimal repair, preventive maintenance and overhaul on the fault rate of the machine are calculated. An algorithm combining the heuristic rules and tabu search is proposed to solve the presented selective maintenance model. Finally, a case study on the maintenance decision-making problem of a connecting rod machining line in the automobile engine workshop is presented to illustrate the applicability of the proposed method. The end result shows that the fault losses can be further reduced by the optimization of maintenance interval and maintenance duration. Copyright (C) 2010 John Wiley & Sons, Ltd.\",\n \"Title: A Multi-agent System for Cross-Organizational Workflows Management Based on Process-View\\nYear: 2007\\n\\nAbstract: Workflow interoperability across enterprises boundaries presents a significant challenge recently. Process-view provides a promising way to cross-organizational workflows design. A multi-agent system combined with Petri net based process-view approach is proposed to facilitate cross-organizational workflows management. Within this multi-agent system, a Petri net algebra model and a character string mapping algorithm are proposed to automate the mapping from a Petri net workflow model to a process-view workflow model; the synchronization points are added to integrated process-view workflow models to coordinate the execution of cross-organizational workflow instances.\",\n \"Title: Reliability Assessment of Machining Accuracy on Support Vector Machine\\nYear: 2008\\n\\nAbstract: In order to establish the reliability model of limited samples, a kind of support vector machine (SVM) tools LSSVM.M is used to process reliability assessment data. The choice of parameters is the key factor to affect the forecasting accuracy. To improve the accuracy, a method of advanced parameters choice is proposed, which consists of two steps. First step is to optimize the scope of parameters, gradually narrowing the initial large scope. The next step is to find out the optimal parameters. Finally, the reliability model of NC machining accuracy was established, and the prediction result in NC machining accuracy case proves that this method is valid and effective.\",\n \"Title: An active learning genetic algorithm for integrated process planning and scheduling\\nYear: 2012\\n\\nAbstract: In traditional approaches, process planning and scheduling are carried out sequentially, where scheduling is done separately after the process plan has been generated. However, the functions of these two systems are usually complementary. The traditional approach has become an obstacle to improve the productivity and responsiveness of the manufacturing system. If the two systems can be integrated more tightly, greater performance and higher productivity of a manufacturing system can be achieved. Therefore, the research on the integrated process planning and scheduling (IPPS) problem is necessary. In this paper, a new active learning genetic algorithm based method has been developed to facilitate the integration and optimization of these two systems. Experimental studies have been used to test the approach, and the comparisons have been made between this approach and some previous approaches to indicate the adaptability and superiority of the proposed approach. The experimental results show that the proposed approach is a promising and very effective method on the research of the IPPS problem.\",\n \"Title: Interoperability Of Cross-Organizational Workflows Based On Process-View For Collaborative Product Development\\nYear: 2008\\n\\nAbstract: Collaborative product development (CPD) has been widely accepted as an advanced collaboration paradigm that combines geographically distributed product development teams to develop product collaboratively and efficiently. Interoperability of cross-organizational workflows is important for CPD to facilitate the successful execution of the whole product development process across enterprises boundaries. This article, describes a timed colored petri net (TCPN) and process-view combined approach to construct cross-organizational workflows, and a three models framework of 'TCPN workflow models - Process- view workflow models - Integrated process-view workflow model' is proposed to realize the interoperability of cross-organizational workflows for CPD. A multi-agent system PVMAS provides a mediated architecture for distributed workflow management systems interoperability among cooperative enterprises. Under this architecture, a service discovery algorithm is provided for discovering the most suitable services enterprises need, a TCPN algebra model and a character string mapping algorithm are proposed to automate the mapping from a TCPN workflow model to a process-view workflow model, and the synchronization points are designated in the integrated process-view workflow model to coordinate the execution of cross-organizational workflow instances. Finally, a case study of the collaborative development of a motorcycle is presented to verify the validity of our approach for cross-organizational workflows interoperability in CPD.\",\n \"Title: Sequencing Mixed-Model Assembly Lines with Limited Intermediate Buffers by a GA/SA-Based Algorithm\\nYear: 2008\\n\\nAbstract: This study is concerned about how to optimize the input sequence of product models in Mixed-Model Assembly Lines (MMALs) with limited intermediate buffers. Two objectives are considered simultaneously: minimizing the variation in parts usage and minimizing the makespan. The mathematical model is presented by incorporating the two objectives according to their relative importance weights. A hybrid algorithm (GASA), based on a genetic algorithm (GA) and a simulated annealing algorithm (SA), is proposed for solving the model. The performance of the GASA is compared with the GA over various test problems. The results show that, in terms of solutions' quality, both the GASA and GA can find the same best solution for small-sized problems and the GASA performs better than the GA for mediate and large-sized problems. Moreover, the impact of buffer size on MMAL's performance is investigated.\",\n \"Title: Analysis of horizontal machining center field failure data based on generalized linear mixed model - a case study\\nYear: 2011\\n\\nAbstract: In order to assess the operational reliability of the horizontal machining center (HMC), field failure data for 14 HMCs over one year are collected from an engine plant of a large automobile manufacturing company in China. In contrast with the usual approach, which just pools the data from all copies under the assumption that each copy is modeled by the same power law processes (PLP), a new model based on the generalized linear mixed model (GLMM) is proposed for analyzing the failure data from all copies of HMC. A basic idea of this method is to assume heterogeneity among all copies of HMC; it is also found that the underlying model for each individual copy is a PLP model with different shape parameters and scale parameters in the GLMM model. This method can make inferences about both the population and each individual copy. Meanwhile, the modified Anderson-Darling test is adapted to the goodness-of-fit test of the model. The results of the analysis suggest that this method is effective to analyze reliability of HMC. Copyright (C) 2010 John Wiley & Sons, Ltd.\",\n \"Title: Multi-objective Topology Optimization of Structures Using NN-OC Algorithms\\nYear: 2007\\n\\nAbstract: Topology optimization problem, which involves many design variables, is commonly solved by finite element method, a method must recalculate structure-stiffness matrix each time of analysis. OC method is a good way to solve topology optimization problem, nevertheless, it can not solve multiobjective topology optimization problems. This paper introduces an effective solution to Multi-objective topology optimization problems by using Neural Network algorithms to improve the traditional OC method. Specifically, in each iteration, calculate the new neural network link weight vector by using the previous link weight vector in the last iteration and the compliance vector in the last time of optimization, then work out the impact factor of each optimization objective on the overall objective of the optimization in order to determine the optimal direction of each design variable.\",\n \"Title: A process simulation based method for scheduling product design change propagation\\nYear: 2012\\n\\nAbstract: It is expected by enterprises that design changes that occur in a complex product development process can be resolved in a cost-effective way so that products modified for new customer requirements or new technology can be launched into the market without increasing much cost and time. Usually there are different solutions or methods for design changes, which may have different impacts on the whole process. Since a complex product development process consists of many design tasks and different relationships among these tasks, it is not easy to analytically compute the completion time when change propagation finishes. In this paper a process simulation based method is proposed to select the most economic propagation path for each design change, which can reduce the total process time for changes occurring in the complex product development process. ''And/Or'' graph nodes are used to represent the input and output logics of each task in the design process. Mathematic models are developed to calculate the completion time of the change propagation process. Monte Carlo based simulation algorithms for finding feasible output paths and calculating impacts of input changes on tasks are developed in order to simulate the change propagation process. The objective function for scheduling design change propagations is obtained by the regression analysis of simulation results. And the best change propagation paths, which usually are not the real optimum of the original design process model, are given by optimizing the regression model with a commercial optimization package. The effect of the method is demonstrated with a study of change propagations in the motor cycle engine design process.\",\n \"Title: A Novel Approach for Process Planning Using Polychromatic Sets and Fuzzy Sets\\nYear: 2007\\n\\nAbstract: Process planning is a task that determines the detailed manufacturing steps for transforming a raw material into a completed part, by utilizing the available machining resources. It involves multiple decision-making activities, such as operation-type selection, operation-method (machine, tool, and tool approach direction) selection, and operations sequencing. This study aims to developing an approach for process planning based on polychromatic sets and fuzzy sets. A complete flow and model is established for processing method seeking, processing route generation, and optimal route selection. The verification, grounding on a true model, is performed for the proposed model to prove the well practicability of this method.\",\n \"Title: A late acceptance hill-climbing algorithm for balancing two-sided assembly lines with multiple constraints\\nYear: 2015\\n\\nAbstract: Two-sided assembly lines are widely applied to produce the large-sized high-volume products, such as buses and trucks. Balancing the lines is a vital design problem for the industries, and the problem is NP-hard. Besides the fundamental constraints of the conventional line balancing problem, some specific constraints may occur in the two-sided assembly line problem, including the zoning constraints, the positional constraints, and the synchronism constraints, which make the problem more complex. In this paper, an integer programming (IP) model is constructed and solved for the two-sided assembly line balancing problem which contains the above three constraints. A novel metaheuristic named late acceptance hill-climbing (LAHC) is also proposed to solve the problem effectively. The proposed algorithm is tested on several sets of instances. The computational results of the LAHC algorithm are compared with those of IP and the lower bounds of the instances. The experiment validates the effectiveness of the LAHC algorithm.\",\n \"Title: An effective hybrid honey bee mating optimization algorithm for balancing mixed-model two-sided assembly lines.\\nYear: 2015\\n\\nAbstract: Mixed-model two-sided assembly lines are widely used in a range of industries for their abilities of increasing the flexibility to meet a high variety of customer demands. Balancing assembly lines is a vital design issue for industries. However, the mixed-model two-sided assembly line balancing (MTALB) problem is NP-hard and difficult to solve in a reasonable computational time. So it is necessary for researchers to find some efficient approaches to address this problem. Honey bee mating optimization (HBMO) algorithm is a population-based algorithm inspired by the mating process in the real colony and has been applied to solve many combinatorial optimization problems successfully. In this paper, a hybrid HBMO algorithm is presented to solve the MTALB problem with the objective of minimizing the number of mated-stations and total number of stations for a given cycle time. Compared with the conventional HBMO algorithm, the proposed algorithm employs the simulated annealing (SA) algorithm with three different neighborhood structures as workers to improve broods, which could achieve a good balance between intensification and diversification during the search. In addition, a new encoding and decoding scheme, including the adjustment of the final mated-station, is devised to fit the MTALB problem. The proposed algorithm is tested on several sets of instances and compared with Mixed Integer Programming (MIP) and SA. The superior results of these instances validate the effectiveness of the proposed algorithm.\",\n \"Title: An effective hybrid teaching-learning-based optimization algorithm for permutation flow shop scheduling problem.\\nYear: 2014\\n\\nAbstract: •A teaching–learning-based optimization is proposed for flow shop problem.•A variable neighborhood search is proposed for fast solution improvement.•A simulated annealing is adopted as the local search method of VNS.•For the DMU problems, some new upper bounds have been obtained.\",\n \"Title: A new methodology for multi-objective multidisciplinary design optimization problems based on game theory\\nYear: 2015\\n\\nAbstract: We propose a new method based on gene expression programming and Nash equilibrium.The solutions are better than some solutions of other methods.The new method can obtain a better Nash solution with more accurate approximation. The design of engineering systems often involves multiple disciplines and competing objectives, which requires coordination, information exchange and share amongst the disciplines. However, in practical design environments, designers have to make decisions in isolation due to organization barriers, time schedules and geographical constraints. This paper will propose a new approach for the multi-objective multidisciplinary design optimization (MDO) problems in non-cooperative environments based on gene expression programming (GEP) and Nash equilibrium in the game theory. In this approach, the GEP method is used as a surrogate to construct the approximate rational reaction sets (RRSs) in the Nash model. The effectiveness of the proposed method is demonstrated by the design of a thin-walled pressure vessel and the hull form parameter design of a small waterplane area twin hull (SWATH) ship. The results show that this approach can fully explore and provide the explicit functional relationship between the strategy of an isolated player and the control variables of the other players, thus able to obtain a better Nash equilibrium solution.\",\n \"Title: An adaptive global variable fidelity metamodeling strategy using a support vector regression based scaling function.\\nYear: 2015\\n\\nAbstract: •We propose a difference adaptive decreasing variable-fidelity metamodeling approach.•SVR is adopted to map the difference between high-fidelity and low-fidelity models.•The presented approach can utilize the already-acquired information during modeling.•Effectiveness of DAD-VFM is demonstrated via several numerical and engineering cases.\",\n \"Title: Optimization of laser welding process parameters of stainless steel 316L using FEM, Kriging and NSGA-II.\\nYear: 2016\\n\\nAbstract: Multi-objective laser welding process parameters optimization approach is proposed.The effects of process parameters on bead profile in light of Kriging are analyzed.Experiment results show the efficiency of the proposed approach. Laser welding process parameters have significant effects on the welding bead profile and quality of the welding joint. This paper proposes an integration method of process parameters optimization using finite element method (FEM), Kriging metamodels and nondominated sorting genetic algorithm II (NSGA-II) in laser welding for stainless steel 316L. The process parameters in this study are laser power (LP), welding speed (WS) and laser focal position (LF). Firstly, a three-dimensional thermal finite element model is developed to obtain the simulated results of bead width (BW) and depth of penetration (DP). Then, Kriging metamodels are constructed to reflect the relationship between input process parameters and output responses. Finally, NSGA-II is used to search for multi-objective Pareto optimal solutions. In addition, the main effects and contribution rates of multiple process parameters on welding bead profile are analyzed. The results of verification experiments indicate that the optimal process parameters are effective and reliable for producing expected welding bead profile.\",\n \"Title: An active learning metamodeling approach by sequentially exploiting difference information from variable-fidelity models.\\nYear: 2016\\n\\nAbstract: We propose an active learning variable-fidelity metamodeling approach (AL-VFM).Information from high-fidelity and low-fidelity models is integrated in AL-VFM.An active learning strategy is introduced to use the already-acquired information.Numerical and engineering cases verify the applicability of the proposed approach. Complex system engineering design optimization based on simulation is a very time-consuming, even computationally prohibitive process. To relieve the computational burden, metamodels are commonly used to replace the computation-intensive simulations. In this paper, an active learning variable fidelity (VF) metamodeling approach (AL-VFM) is proposed for the purpose of integrating information from both low-fidelity (LF) and high-fidelity (HF) models. In AL-VFM, Kriging metamodel is adopted to map the difference between the HF and LF models aiming to approach the HF model on the entire domain. Besides, a general active learning strategy is introduced in AL-VFM to make full use of the already-acquired information to guide the VF metamodeling. The already-acquired information represents the location of regions where the differences between the HF and LF models are multi-model, non-smooth and have abrupt changes. Several numerical and engineering cases with different degrees of difficulty verify the applicability of the proposed VF metamodeling approach.\",\n \"Title: An active learning radial basis function modeling method based on self-organization maps for simulation-based design problems.\\nYear: 2017\\n\\nAbstract: The radial basis function has been widely used in constructing metamodels as response surfaces. Yet, it often faces the challenge of accuracy if a sequential sampling strategy is used to insert samples sequentially and refine the models, especially under the constraint of computational resources. In this paper, a sensitive region pursuing based active learning radial basis function (SRP-ALRBF) metamodeling approach is proposed to sequentially exploit the already-acquired knowledge in the modeling process for obtaining a desirable estimation of the relationship between the input design variables and the output response. In this method, the leave-one-out (LOO) errors of each sample point are taken to identify the boundaries of sensitive regions. According to the obtained LOO information, the original design space is divided into some subspaces by adopting the self-organization maps (SOMs). The boundary of the most sensitive region, where the output response is multi-modal or non-smooth with abrupt changes, is determined by the topological graph generated by cluster analysis in SOMs. In the most sensitive region, infill sample point searching is performed based on an optimization formulation. Ten numerical examples are used to compare the proposed SRP-ALRBF with four existing active learning RBF metamodeling approaches. Results show the advantage of the proposed SRP-ALRBF approach in both prediction accuracy and robustness. It is also applied to three engineering cases to illustrate its ability to support complex engineering design.\",\n \"Title: A variable fidelity information fusion method based on radial basis function.\\nYear: 2017\\n\\nAbstract: A variable-fidelity information fusion approach based on RBF is proposed.The low-fidelity output is taken as a prior-knowledge of the studied system.Cases study show the applicability and efficiency of the proposed approaches. Radial basis function (RBF) model has been widely used in complex engineering design process to replace the computational-intensive simulation models. This paper proposes a variable-fidelity metamodeling (VFM) approach based on RBF, in which different levels fidelity information can be integrated and fully exploited. In the proposed VFM approach, a RBF metamodel is constructed for the low-fidelity (LF) model as a start. Then by taking the constructed LF metamodel as a prior-knowledge and mapping the output space of the LF metamodel to that of the studied high-fidelity (HF) model, a variable fidelity (VF) metamodel is created to approximate the relationships between the design variables and corresponding output responses. A numerical illustrative example is adopted to make a detailed comparison between the VFM approach developed in this research and three existing scaling function based VFM approaches, considering different sample sizes and sample noises. Results illustrate that the proposed VFM approach outperforms the scaling function based VFM approaches both in global and local accuracy. Then the proposed VFM approach is applied to two engineering problems, modeling aerodynamic data for a three-dimensional aircraft and the prediction of weld bead profile in laser welding, to illustrate its ability in support of complex engineering design.\",\n \"Title: A sequential multi-fidelity metamodeling approach for data regression.\\nYear: 2017\\n\\nAbstract: •A sequential multi-fidelity (SMF) metamodeling approach is proposed.•Different fidelity information can be incorporated in SMF metamodeling process.•Where to allocate low-fidelity (LF) and high-fidelity (HF) sample points is solved.•How to split the total computational budget between LF and HF models is addressed.•The effectiveness and merits of the proposed SMF method are tested on three cases.\",\n \"Title: Multiobjective Program and Hybrid Imperialist Competitive Algorithm for the Mixed-Model Two-Sided Assembly Lines Subject to Multiple Constraints.\\nYear: 2018\\n\\nAbstract: A mixed-model two-sided assembly line is a manufacturing system designed for the production of large-sized products. In order to describe the actual condition, this paper presents a novel multiobjective programming model for balancing a mixed-model two-sided assembly line subject to multiple constraints, in which, additional constraints including zoning, synchronous, and positional constraints are considered besides the traditional constraints, e.g., the precedence constraint. Two objectives are simultaneously to be optimized, one is to minimize the combination of the weighted line efficiency and the weighted smoothness index, and the other is to minimize the weighted total relevant costs per unit of a product. A novel multiobjective hybrid imperialist competitive algorithm (MOHICA) is proposed to solve this problem. In the presented MOHICA, the sigma method is employed to quantify every individual, a novel merging method is introduced to reserve better individuals into the evolutionary population, and late acceptance hill-climbing (LAHC) algorithm is presented as a local search algorithm to achieve accurate balance between intensification and diversification. The experimental results on the selected benchmark instances and a practical case show that the proposed multiobjective algorithm outperforms nondominated sorting genetic algorithm (NSGA)-II, multiobjective improved teaching-learning-based optimization, and NSGA-III existing in the literature.\",\n \"Title: A space mapping method based on Gaussian process model for variable fidelity metamodeling.\\nYear: 2018\\n\\nAbstract: •A space mapping based variable-fidelity metamodeling approach is developed.•The low-fidelity information is taken as a prior-knowledge of the studied system.•A mathematic example is used for step-by-step illustration.•The proposed approach is applied to two real-life cases.\",\n \"Title: An on-line variable fidelity metamodel assisted Multi-objective Genetic Algorithm for engineering design optimization.\\nYear: 2018\\n\\nAbstract: •An on-line variable-fidelity metamodel (VFM) assisted Multi-Objective Genetic Algorithms (OLVFM-MOGA) approach is proposed to ease the computational burden.•A novel model management strategy is adopted to update the VFM to improve optimization quality.•Metamodel uncertainty and computational cost of different fidelity models are considered in proposed approach.•Cases study shows the applicability and efficiency of the proposed approaches.\",\n \"Title: An adaptive sampling strategy for Kriging metamodel based on Delaunay triangulation and TOPSIS.\\nYear: 2018\\n\\nAbstract: Metamodels have been widely used in engineering design and optimization. Sampling method plays an important role in the constructing of metamodels. This paper proposes an adaptive sampling strategy for Kriging metamodel based on Delaunay triangulation and TOPSIS (KMDT). In the proposed KMDT, Delaunay triangulation is employed to partition the design space according to current sample points. The area of each partitioned triangle is used to indicate the degree of dispersion of sample points, and the prediction error of Kriging metamodel at each triangle’s centroid is used to represent the local error of each triangle region. By calculating the weight of the area and prediction error for each triangle region using the entropy method and TOPSIS, the degree of dispersion of sample points and local errors of metamodel are taken into consideration to make a trade-off between global exploration and local exploitation during the sequential sampling process. As a demonstration, the proposed approach is compared to other three sampling methods using several numerical cases and the modeling of the aerodynamic coefficient for a three-dimensional aircraft. The result reveals that the proposed approach provides more accurate metamodel at the same simulation cost, which is very important in metamodel-based engineering design problems.\",\n \"Title: Multi-sensor information fusion for remaining useful life prediction of machining tools by adaptive network based fuzzy inference system.\\nYear: 2018\\n\\nAbstract: •A multi-sensor information fusion system for online RUL prediction of machining tools is designed.•An improved EEMD method is proposed for attenuating undesired signals and solving mode mixing problem.•Statistics features are respectively extracted by segmentation in time domain and frequency domain.•Optimal features are selected based on essential characteristics of these extracted features, which include correlation, monotonicity, and autocorrelation.•An ANFIS architecture with subtraction clustering and fuzzy space partition is designed for the feature fusion and online RUL prediction.\",\n \"Title: Degradation Data-Driven Time-To-Failure Prognostics Approach for Rolling Element Bearings in Electrical Machines.\\nYear: 2019\\n\\nAbstract: Time-to-failure (TTF) prognostic plays a crucial role in predicting remaining lifetime of electrical machines for improving machinery health management. This paper presents a novel three-step degradation data-driven TTF prognostics approach for rolling element bearings (REBs) in electrical machines. In the degradation feature extraction step, multiple degradation features, including statistical fe...\",\n \"Title: Machine Health Monitoring Using Adaptive Kernel Spectral Clustering and Deep Long Short-Term Memory Recurrent Neural Networks.\\nYear: 2019\\n\\nAbstract: Machine health monitoring is of great importance in industrial informatics field. Recently, deep learning methods applied to machine health monitoring have been proven effective. However, the existing methods face enormous difficulties in extracting heterogeneous features indicating the variation until failure and revealing the inherent high-dimensional features of massive signals, which affect th...\",\n \"Title: Design A Degradation Condition Monitoring System Scheme For Rolling Bearing Using Emd And Pca\\nYear: 2017\\n\\nAbstract: Purpose - Rolling bearings based on rotating machinery are one of the most widely used in industrial applications because of their low cost, high performance and robustness. The purpose of this paper is to describe how to identify degradation condition of rolling bearing and predict its fault time in big data environment in order to achieve zero downtime performance and preventive maintenance for the rolling bearing.Design/methodology/approach - The degradation characteristic parameters of rolling bearings including intrinsic mode energy and failure frequency were, respectively, extracted from the pre-processed original vibration signals using EMD and Hilbert transform. Then, Spearman's rank correlation coefficient and PCA were used to obtain the health index of the rolling bearing so as to detect the appearance of degradations. Furthermore, the degradation condition of the rolling bearings might be identified through implementing the monotonicity analysis, robustness analysis and degradation analysis of the health index.Findings - The effectiveness of the proposed method is verified by a case study. The result shows that the proposed method can be applied to monitor the degradation condition of the rolling bearings in industrial application.Research limitations/implications - Further experiment remains to be done so as to validate the effectiveness of the proposed method using Apache Hadoop when massive sensor data are available.Practical implications - The paper proposes a methodology for rolling bearing condition monitoring representing the steps that need to be followed. Real-time sensor data are utilized to find the degradation characteristics.Originality/value - The result of the work presented in this paper form the basis for the software development and implementation of condition monitoring system for rolling bearings based on Hadoop.\",\n \"Title: A multi-fidelity information fusion metamodeling assisted laser beam welding process parameter optimization approach.\\nYear: 2017\\n\\nAbstract: A multi-fidelity (MF) metamodel assisted welding parameter optimization is proposed.A 3D thermal finite element model is developed as a low-fidelity model.A laser welding physical experiment is taken as the high-fidelity model.The MF metamodel is built based on two different levels fidelity information fusion.Verification experiments illustrated the reliability of the final optima. Selecting reasonable laser beam welding (LBW) process parameters is very helpful for obtaining a good welding bead profile and hence a high quality of the welding joint. Existing process parameter optimization approaches for LBW either based on cost-expensive physical experiments or low-fidelity (LF) computer simulations. This paper proposes a multi-fidelity (MF) metamodel based LBW process parameter optimization approach, in which different levels fidelity information, both from LF computer simulations and high-fidelity (HF) physical experiments can be integrated and fully exploited. In the proposed approach, a three-dimensional thermal finite element model is developed as the LF model, which is fitted with a LF metamodel firstly. Then, by taking the LF metamodel as a base model and scaling it using the HF physical experiments, a MF metamodel is constructed to approximate the relationships between the LBW process parameters and the bead profile. Two metrics are adopted to compare the prediction accuracy of the MF metamodel with the single-fidelity metamodels solely constructed with physical experiments or computer simulations. Results illustrate that the MF metamodel outperforms the single-fidelity metamodels both in global and local accuracy. Finally, the fast elitist non-dominated sorting genetic algorithm (NSGA-II) is used to facilitate LBW process parameter space exploration and multi-objective Pareto optima search. LBW verification experiments verify the effectiveness and reliability of the obtained optimal process parameters.\",\n \"Title: Mathematical Modelling And Optimisation Of Energy-Conscious Hybrid Flow Shop Scheduling Problem With Unrelated Parallel Machines\\nYear: 2019\\n\\nAbstract: This paper investigates an energy-conscious hybrid flow shop scheduling problem with unrelated parallel machines (HFSP-UPM) with the energy-saving strategy of turning off and on. We first analyse the energy consumption of HFSP-UPM and formulate five mixed integer linear programming (MILP) models based on two different modelling ideas namely idle time and idle energy. All the models are compared both in size and computational complexities. The results show that MILP models based on different modelling ideas vary dramatically in both size and computational complexities. HFSP-UPM is NP-Hard, thus, an improved genetic algorithm (IGA) is proposed. Specifically, a new energy-conscious decoding method is designed in IGA. To evaluate the proposed IGA, comparative experiments of different-sized instances are conducted. The results demonstrate that the IGA is more effective than the genetic algorithm (GA), simulating annealing algorithm (SA) and migrating birds optimisation algorithm (MBO). Compared with the best MILP model, the IGA can get the solution that is close to an optimal solution with the gap of no more than 2.17% for small-scale instances. For large-scale instances, the IGA can get a better solution than the best MILP model within no more than 10% of the running time of the best MILP model.\",\n \"Title: Multisensory Data-Driven Health Degradation Monitoring of Machining Tools by Generalized Multiclass Support Vector Machine.\\nYear: 2019\\n\\nAbstract: Health degradation monitoring of machining tools is of great importance in industrial application field. In this paper, a novel multisensory data-driven health degradation monitoring system schema for the machining tools is proposed by using a generalized multiclass support vector machine (GenSVM). In this schema, multidimensional feature extraction is implemented in the time domain, frequency domain, and time-frequency domain based on the time domain statistical analysis, power spectrum analysis, and complete ensemble empirical mode decomposition with adaptive noise, respectively. On the basis, effective features that are strongly associated with the degradation process are picked out using a Pearson correlation coefficient. Meanwhile, a new and flexible GenSVM model is constructed to identify the health state of machining tools, which integrates a simplex encoding and iterative majorization optimization algorithm. A practical application case study is implemented to verify the effectiveness of the proposed method. The results show the superior performance of the proposed method compared with other standard methods.\",\n \"Title: Sensor Data-Driven Bearing Fault Diagnosis Based on Deep Convolutional Neural Networks and S-Transform.\\nYear: 2019\\n\\nAbstract: Accurate and timely bearing fault diagnosis is crucial to decrease the probability of unexpected failures of rotating machinery and improve the efficiency of its scheduled maintenance. Since convolutional neural networks (CNN) have poor feature extraction capability for sensor data with 1D format, CNN combined with signal processing algorithm is often adopted for fault diagnosis. This increases manual conversion work and expertise dependence while reducing the feasibility and robustness of the corresponding fault diagnosis method. In this paper, a novel sensor data-driven fault diagnosis method is proposed by fusing S-transform (ST) algorithm and CNN, namely ST-CNN. First of all, a ST layer is designed based on S-transform algorithm. In the ST layer, sensor data is automatically converted into 2D time-frequency matrix without manual conversion work. Then, a new ST-CNN model is constructed, and the time-frequency coefficient matrixes are inputted into the constructed ST-CNN model. After the training process of the ST-CNN model is completed, the classification layer such as softmax performs the fault diagnosis. Finally, the diagnosis performance of the proposed method is evaluated by using two public available datasets of bearings. The experimental results show that the proposed method performs the higher and more robust diagnosis performance than other existing methods.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":61,"string":"61"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":281,"string":"281"}}},{"rowIdx":282,"cells":{"question_id":{"kind":"string","value":"Jianzong Wang"},"question":{"kind":"string","value":"Generate an abstract for the title \"Anomaly Removal for Vehicle Energy Consumption in Federated Learning\" using the following items: federated learning, intelligent transportation system, anomaly removal, neural network, vehicle data."},"answer":{"kind":"string","value":"Federated learning is a distributed deep learning method that enables parallel and distributed learning of data on multiple participants, without the need to centrally store it. In intelligent transportation system, it is impractical to gather the vehicle data from the edge devices due to data privacy concerns or network bandwidth limitation. Hence, combining with federated learning to train vehicle data processing models has become one of the popular solutions. However, such computing paradigm is subject to threats posed by malicious and abnormal nodes that greatly reduces the computing power of the neural network when performing calculations in a distributed manner. In this paper, we use the Vehicle Energy Dataset to simulate distributed vehicle data. Based on these data, we propose an unsupervised anomaly removal and neural network model based on federated learning to solve the problem of outlier data on vehicle equipment and analyze the effect of speed on fuel consumption. The results show that with the proposed anomaly removal strategy, MAE and MSE of the trained network are 29% and 36% lower than those without anomaly removal, respectively."},"correct_answer":{"kind":"string","value":"Federated learning is a distributed deep learning method that enables parallel and distributed learning of data on multiple participants, without the need to centrally store it. In intelligent transportation system, it is impractical to gather the vehicle data from the edge devices due to data privacy concerns or network bandwidth limitation. Hence, combining with federated learning to train vehicle data processing models has become one of the popular solutions. However, such computing paradigm is subject to threats posed by malicious and abnormal nodes that greatly reduces the computing power of the neural network when performing calculations in a distributed manner. In this paper, we use the Vehicle Energy Dataset to simulate distributed vehicle data. Based on these data, we propose an unsupervised anomaly removal and neural network model based on federated learning to solve the problem of outlier data on vehicle equipment and analyze the effect of speed on fuel consumption. The results show that with the proposed anomaly removal strategy, MAE and MSE of the trained network are 29% and 36% lower than those without anomaly removal, respectively."},"documents":{"kind":"list like","value":["Title: Avoiding performance fluctuation in cloud storage\nYear: 2010\n\nAbstract: Cloud computing is an elastic computing model whereby users can lease computing and storage resources on demand from a remote infrastructure. Cloud computing is gaining popularity due to its low cost, high reliability and wide availability. However, a serious impediment to its wider deployment is the relative lack of effective data management services. The relatively slow access to persistent data and large variability in cloud storage I/O performance, can significantly degrade the performance of data-intensive applications. This paper addresses the problem of I/O performance fluctuation and proposes an automatic optimization schema for cloud storage called AOSC, which utilizes data chunking, placement, and replication to achieve more stable and predictable performance. Our experimental results based on Amazon Elastic Cloud Computing (EC2) data center show that AOSC can improve the stability and help provide better performance guarantees for cloud computing.","Title: Reducing Storage Overhead with Small Write Bottleneck Avoiding in Cloud RAID System\nYear: 2012\n\nAbstract: Cloud storage systems commonly use replication of stored data sets to ensure high reliability and availability. However, the high storage overhead of replication becomes increasingly unacceptable with the explosive growth of data stored in cloud. Some cloud storage systems have attempted to replace replication with erasure coding to reduce storage overhead, that is just the thinking behind Cloud RAID. A well-designed Cloud RAID mechanism should achieve the right tradeoffs between storage efficiency, performance, and reliability. As there exists no widely-accepted methods for Cloud RAID, we present a workloads-based Cloud RAID schema-Selective Cloud RAID (SCR for short). SCR treats primary storage and backup storage with different RAIDmethods, the former at the level of directories, and the latter at the level of individual files. SCR has three distinct advantages over previous attempts at Cloud RAID: (1) it can significantly reduce the storage overhead compared with threeway replication, (2) it can avoid most cases of the \"small write bottleneck\" and simplify system maintenance, (3) its implementation is modular, therefore, it is easy to configure different erasure codes for different workloads. Additionally, we have implemented a SCR prototype with RDP code, which shows significant benefits over Blaum-Roth codes in degraded read performance. To verify the effectiveness of SCR, we perform theoretical analysis and elaborate benchmark tests to evaluate the performance of SCR prototype.","Title: RO-BURST: A Robust Virtualization Cost Model for Workload Consolidation over Clouds\nYear: 2012\n\nAbstract: As more public cloud computing platforms are emerging in the market, a great challenge for these Infrastructure as a Server (IaaS) providers is how to measure the cost and charge the Software as a Service (SaaS) clients for the cloud computing services. This problem is compounded as virtualization technology is deployed in many cloud platforms to consolidate servers and improve their utilization. This paper studies three different but related models for apportioning costs in a private or public cloud environment supported by virtualized data centers. With given workload placement scenarios and randomly selected workloads, these models estimate the cost for each workload. Through simulations and thorough comparisons of the results, we finally champion the RO-BURST model tailored for the service providers' need, that is characterized by robustness and burstiness. What is more, we import Cost Volatility Factors to ensure that our model is able to adjust itself to the market and multiform demands in power and hardware components, such as disks and CPU, showing its compatibility and extensibility. We also come up with a pricing strategy with respect to servers the workload employs, which generates an applicable and less placement-sensitive fee for the clients.","Title: Robot: An efficient model for big data storage systems based on erasure coding\nYear: 2013\n\nAbstract: It is well-known that with the explosive growth of data, the age of big data has arrived. How to save huge amounts of data is of great importance to both industry and academia. This paper puts forward a solution based on coding technologies in big data system that store a lot of cold data. By studying existing coding technologies and big data systems, we can not only maintain the system's reliability, but also improve the security and the utilization of storage systems. Due to the remarkable reliability and space saving rate of coding technologies, importing coding schema in to big data systems becomes prerequisite. In our presented schema, the storage node is divided into several virtual nodes to keep load balancing. By setting up different virtual node storage groups for different codec server, we can ensure system availability. And by utilizing the parallel decoding computing of the node and the block of data, we can also reduce the system recovery time when data is corrupted. Additionally, different users set different coding parameters can improve the robustness of big data storage systems. We configure various data block m and calibration block k to improve the utilization rate in the quantitative experiments. The results shows that parallel decoding speed can rise up two times than the past serial decoding speed. The encoding efficiency with ICRS coding is 34.2% higher than using CRS and 56.5% more than using RS coding equally. The decoding rate by using ICRS is 18.1% higher than using CRS and 31.1% higher than using RS averagely.","Title: pCloud: an adaptive i/o resource allocation algorithm with revenue consideration over public clouds\nYear: 2012\n\nAbstract: Cloud-based services are emerging as an economical and convenient alternative for clients who don't want to acquire, maintain and operate their own IT equipment. Instead, customers purchase virtual machines (VMs) with certain Service Level Objectives (SLOs) to obtain computational resources. Existing algorithms for memory and CPU allocation are inadequate for I/O allocation, especially in clustered storage infrastructures where storage is distributed across multiple storage nodes. This paper focuses on: (1) dynamic SLO decomposition so VMs receive proper I/O service in each distributed storage node, and (2) efficient and robust local I/O scheduling strategy. To address these issues, we present pCloud, an adaptive I/O resource allocation algorithm that at runtime adjusts local SLOs. The local SLOs are generated for each VM at each storage node based on access patterns. We also adopt dual clocks in pCloud to allow automatic switching between two scheduling strategies. When system capacity is sufficient, pCloud interweaves requests in an earliest deadline first (EDF) manner. Otherwise resources are allocated proportionate to their normalized revenues. The results of our experiments suggest that pCloud is adaptive to various access patterns without significant manual pre-settings while maximizing profits.","Title: Data Mining of Mass Storage Based on Cloud Computing\nYear: 2010\n\nAbstract: Cloud computing is an elastic computing model that the users can lease the resources from the rentable infrastructure. Cloud computing is gaining popularity due to its lower cost, high reliability and huge availability. To utilize the powerful and huge capability of cloud computing, this paper is to import it into data mining and machine learning field. As one of the most influential and open competition in machine learning area, Netflix Prize attached with mass storage had driven thousands of teams across the world to attack the problem, among which the final winner was BellKor's Pragmatic Chaos team, who bested Netflix's own algorithm for predicting ratings by 10%. Their solution is an ensemble of a large number of models, each of which specializes in addressing a different aspect of the data. Among such different models, k-nearest neighbors (KNN) and Restricted Boltzmann Machine (RBM) are reported to be two most important and successful models. As a result, we build two predictors based on such two model respectively with the order to testify their performance based on cloud computing platforms. The results show that KNN can achieve root mean square deviation (rmse) with 0:9468 after the Global Effect (GE) data preprocessing, which is better than the Cinematch's performance with rmse being 0:951. The rmse for RBM algorithm is about 0:9670 on the raw dataset, which can be further improved by KNN model.","Title: TRACER: A Trace Replay Tool to Evaluate Energy-Efficiency of Mass Storage Systems\nYear: 2010\n\nAbstract: Improving energy efficiency of mass storage systems has become an important and pressing research issue in large HPC centers and data centers. New energy conservation techniques in storage systems constantly spring up; however, there is a lack of systematic and uniform way of accurately evaluating energy-efficient storage systems and objectively comparing a wide range of energy-saving techniques. This research presents a new integrated scheme, called TRACER, for evaluating energy-efficiency of mass storage systems and judging energy-saving techniques. The TRACER scheme consists of a toolkit used to measure energy efficiency of storage systems as well as performance and energy metrics. In addition, TRACER contains a novel and accurate workload-control module to acquire power varying with workload modes and I/O load intensity. The workload generator in TRACER facilitates a block-level trace replay mechanism. The main goal of the workload-control module is to select a certain percentage (e.g., anywhere from 10% to 100%) of trace entries from a real-world I/O trace file uniformly and to replay filtered trace entries to reach any level of I/O load intensity. TRACER is experimentally validated on a general RAID5 enterprise disk array. Our experiments demonstrate that energy-efficient mass storage systems can be accurately evaluated on full scales by TRACER. We applied TRACER to investigate impacts of workload modes and load intensity on energy-efficiency of storage devices. This work shows that TRACER can enable storage system developers to evaluate energy efficiency designs for storage systems.","Title: A Quantitative Evaluation Model for Choosing Efficient Redundancy Strategies over Clouds\nYear: 2012\n\nAbstract: Reliability has always been one of the key issues that draw widespread concerns since the rise of cloud computing. While most cloud systems use replication to ensure high reliability, some scholars incline to try erasure codes in the interest of space efficiency. Comparison of performance and reliability between replication and erasure coding have been widely analyzed by many researchers, but effort to make a thorough understanding of this issue is quite few. In this paper, we defined a quantitative model aimed at comprehensively evaluating the relative merits of the two redundancy schemes in seven metrics (availability, reliability, storage, performance, bandwidth, energy and dollar cost) which will be detailed next, and we exploited this model to provide a reference for Cloud Service Providers (CSPs for short) to set up the right configurations for their cloud file systems. In addition, we presented a scheme to decide on which one of the two redundancy schemes more suitable for a given cloud storage system.","Title: Enhancing shared RAID performance through online profiling\nYear: 2012\n\nAbstract: Enterprise storage systems are generally shared by multiple servers in a SAN environment. Our experiments as well as industry reports have shown that disk arrays show poor performance when multiple servers share one RAID due to resource contention as well as frequent disk head movements. We have studied IO performance characteristics of several shared storage settings of practical business operations. To avoid the IO contention, we propose a new dynamic data relocation technique on shared RAID storages, referred to as DROP, Dynamic data Relocation to Optimize Performance. DROP allocates/manages a group of cache data areas and relocates/drops the portion of hot data at a predefined sub array that is a physical partition on the top of the entire shared array. By analyzing profiling data to make each cache area owned by one server, we are able to determine optimal data relocation and partition of disks in the RAID to maximize large sequential block accesses on individual disks and at the same time maximize parallel accesses across disks in the array. As a result, DROP minimizes disk head movements in the array at run time giving rise to high IO performance. A prototype DROP has been implemented as a software module at the storage target controller. Extensive experiments have been carried out using real world IO workloads to evaluate the performance of the DROP implementation. Experimental results have shown that DROP improves shared IO performance greatly. The performance improvements in terms of average IO response time range from 20% to a factor 2.5 at no additional hardware cost.","Title: A Fine-Grained Data Reconstruction Algorithm for Solid-State Disks\nYear: 2010\n\nAbstract: Solid-state disks (SSDs) with high I/O performance are increasingly becoming popular. To extend the life time of flash memory, one can apply wear-leveling strategies to manage data blocks. However, wear-leveling strategies certainly inevitably degrade write performance. In addition to low write performance, wear-leveling strategies make one block unwritable when one bit of this block is invalid. Although data reconstruction techniques have been widely employed in disk arrays, the reconstruction techniques has not been studied in the context of solid-state disks. In this paper, we present a new fine-grained data-reconstruction algorithm for solid-state disks. The algorithm aims to provide a simple yet efficient wear-leveling strategy that improves both I/O performance and reliability of solid-state disks. Simulation experiments show that all data blocks have very similar in terms of erasure times. The number of extra erasures incurred by our algorithm is very marginal.","Title: C-IRR: An Adaptive Engine for Cloud Storage Provisioning Determined by Economic Models with Workload Burstiness Consideration\nYear: 2012\n\nAbstract: Being the long dreamed vision of computing as a utility, cloud enables convenient and on-demand access to a large centralized pool of resources via network. The emerging of cloud storage offers a rather feasible solution to handle the sheer amount of information. It is maturing and becoming an alternative for on-premise storage. Thus, for IT enterprises with high demand of storage, a big concern is to determine whether it is more cost-effective to lease storage service over clouds. In this paper, we introduce a cloud storage provisioning engine called C-IRR to help users rationally evaluate the benefits of purchasing new disk drives and comparing it against leasing cloud storage offered by Infrastructure as a service (IaaS) providers. We also discuss issues regarding workload burstiness to achieve potential benefit for each applications in local data centers of SaaS providers. The C-IRR migrates the bursty workloads to the clouds and keeps stable ones locally. Such hybrid storage method achieves at least 20% costs saving in total for SaaS companies by experimental evaluation. In addition, C-IRR engine is of adaptivity about fluctuation of storage pricing and manpower cost increasing after the sensitivity studying.","Title: Middleware enabled data sharing on cloud storage services.\nYear: 2010\n\nAbstract: With the emergence of public cloud storage platforms like Amazon, Microsoft and Google etc, individual applications and some enterprise storage are being increasingly deployed on Clouds. However, dynamic data sharing in public clouds face problems of low performance and lack of SLA guarantees. We propose a middleware called mCloud between the Cloud storage and clients to provide data sharing services with better performance and SLA satisfaction. Technologies including virtualization, chunking, and caching, are integrated into mCloud. Experiential results based on Amazon Web Services (AWS) have shown that mCloud is able to improve shared IO performance in term of aggregate IO throughput and help provide better SLAs for cloud storage.","Title: qSDS: A QoS-Aware I/O Scheduling Framework towards Software Defined Storage\nYear: 2015\n\nAbstract: The inadequate resource allocation, lack of I/O performance prediction and insufficient I/O isolation are affecting the storage performance in the multi-tenant cloud storage environment. For Quality of Service (QoS), the Software-defined Storage (SDS) is an effective approach in data centers. However, the lack of intelligence, robustness and self-adjustment are blocking the applications and promotions of SDS heavily. This paper focuses on the QoS-Aware I/O resource scheduling problem to build data centers with high avail- ability, scalability and QoS. We will study workload characteristics, requirement analysis, the theory of QoS in SDS and I/O scheduling strategies. We obtain such goals by proposing a mathematics model of workload burstness, QoS semantic description with rule execution mechanisms and dynamic robust I/O scheduling algorithms for multi-type resources allocation. In the current progress, A QoS-Aware I/O Scheduling Framework towards SDS, qSDS has been proposed for the SSD/HDD hybrid storage. The preliminary evaluation in some benchmarks shows that qSDS can gain better performance compared with other strategies.","Title: OptRS: An Optimized Algorithm Based on CRS Codes in Big Data Storage Systems.\nYear: 2015\n\nAbstract: It is well-known that erasure codes, such as Reed-Solomon (RS) and Cauchy RS (CRS) codes, have played an important roles in big data storage systems to both industry and academia. While RS and CRS codes provide significant saving in storage space, they can impose a huge burden of systems performance while encoding and decoding. By studying existing high reliability and space saving rate of coding technologies, it is urgent to deploy an efficient erasure coding mechanism into distributed storage systems, which is the main storage architecture in big data era.This paper puts forward an optimized algorithm named OptRS (Optimized RS), which can not only guarantee the system’s reliability, but also enhance the efficiency and utilization of storage space. The dominant type of encoding and decoding inside erasure codes is matrix computation. In order to accelerate the speed of calculation, OptRS transferred the computation of matrix Galois field mapping into the XOR operation. Additionally, OptRS has developed the elimination schemes to minimize the numbers of XOR. Through theory analysis, we can conclude that OptRS algorithm improved the performance of encoding and decoding lead to shorten the computation time the same as verified by the test. The encoding efficiency with OptRS coding achieves 36.1 % and 58.2 % acceleration than using CRS and RS coding, respectively. The decoding rate by using OptRS can increase 19.3 % and 33.1 % compared with CRS and RS averagely by quantitative studying.","Title: User Identity Linkage by Latent User Space Modelling\nYear: 2016\n\nAbstract: User identity linkage across social platforms is an important problem of great research challenge and practical value. In real applications, the task often assumes an extra degree of difficulty by requiring linkage across multiple platforms. While pair-wise user linkage between two platforms, which has been the focus of most existing solutions, provides reasonably convincing linkage, the result depends by nature on the order of platform pairs in execution with no theoretical guarantee on its stability. In this paper, we explore a new concept of ``Latent User Space'' to more naturally model the relationship between the underlying real users and their observed projections onto the varied social platforms, such that the more similar the real users, the closer their profiles in the latent user space. We propose two effective algorithms, a batch model(ULink) and an online model(ULink-On), based on latent user space modelling. Two simple yet effective optimization methods are used for optimizing objective function: the first one based on the constrained concave-convex procedure(CCCP) and the second on accelerated proximal gradient. To our best knowledge, this is the first work to propose a unified framework to address the following two important aspects of the multi-platform user identity linkage problem --- (I) the platform multiplicity and (II) online data generation. We present experimental evaluations on real-world data sets for not only traditional pairwise-platform linkage but also multi-platform linkage. The results demonstrate the superiority of our proposed method over the state-of-the-art ones.","Title: Prioritized Grid Highway Long Short-Term Memory-Based Universal Background Model for Speaker Verification.\nYear: 2017\n\nAbstract: Prioritized grid long short-term memory (pGLSTM) has been shown to improve automatic speech recognition efficiently. In this paper, we implement this state-of-the-art model of ASR tasks for text-independent Chinese language speaker verification tasks in which DNN/i-Vector (DNN-based i-Vector) framework is adopted along with PLDA backend. To fully explore the performance, we compared the presented pGLSTM based UBM to GMM-UBM and HLSTM-UBM. Due to constraint of the amount of Chinese transcribed corpus for ASR training, we also explore an adaptation method by firstly training the pGLSTM-UBM on English language with large amount of corpus and use a PLDA adaptation backend to fit into Chinese language before the final speaker verification scoring. Experiments show that both pGLSTM-UBM model with corresponding PLDA backend and pGLSTM-UBM with adapted PLDA backend achieve better performance than the traditional GMM-UBM model. Additionally the pGLSTM-UBM with PLDA backend achieves performance of 4.94% EER in 5 s short utterance and 1.97% EER in 10 s short utterance, achieving 47% and 51% drop comparing to that of GMM. Experiment results imply that DNN from ASR tasks can expand the advantage of UBM model especially in short utterance and that better DNN model for ASR tasks could achieve extra gain in speaker verification tasks.","Title: Assistance of Speech Recognition in Noisy Environment with Sentence Level Lip-Reading.\nYear: 2017\n\nAbstract: Acoustic speech recognition, as a technique to decode text from a speech, receives a great success in recent years. The trained model of Ping An Technology (ShenZhen) Co., Ltd results in a word error rate (WER) of 8.4%, which shows competitive performance among popular business products. However, an assumption of the achievement is the quiet environment of the speech. In a noisy environment, the accuracy will decrease 10%–20%. For the improvement in such environment, a multi-modal biometric system integrating acoustic speech-recognition with sentence level lip-reading is designed. In several noisy situations, the 5.7% averaged word error rate (WER) of the results of our integrated system indicates a significant improvement to the pure acoustic speech-recognition system.","Title: Video-Based Pig Recognition with Feature-Integrated Transfer Learning.\nYear: 2018\n\nAbstract: Automatic detection and recognition of animals has long been a popular topic. It can be used on different areas, such as ecosystem protection, farming industry, insurance industry, etc. Currently, there is still no robust and efficient method for this problem. Deep neural network, a recently rapid developing technology, has shown its great power on image processing, but suffers from low training speed problem. Recently, transfer learning has become popular because it avoids training the network from scratch, which significantly speeds up the training speed. In this paper, we focus on the pig recognition contest organized by a Chinese finance company. Applying all frames for training the neural networks with VGG-19 will result in an accuracy lower than 60% in the prediction steps. With experiments, we find out a key to enhance the accuracy of the video-based pig recognition task is that the frames have to be carefully selected with a certain algorithm. To take advantage of the strengths of different network architectures, we apply feature integration method with the deep neural networks of DPN131, InceptionV3 and Xception network together. We then implement the integrated feature to train the labelled dataset which are frames extracted from the videos of 30 pigs. The resulted model receive an prediction accuracy of 96.41%. Experiments show that the best performance of our proposed methods outperforms all classic deep neural networks training from scratch.","Title: Social Network Monitoring for Bursty Cascade Detection.\nYear: 2018\n\nAbstract: Social network services have become important and efficient platforms for users to share all kinds of information. The capability to monitor user-generated information and detect bursts from information diffusions in these social networks brings value to a wide range of real-life applications, such as viral marketing. However, in reality, as a third party, there is always a cost for gathering information from each user or so-called social network sensor. The question then arises how to select a budgeted set of social network sensors to form the data stream for burst detection without compromising the detection performance. In this article, we present a general sensor selection solution for different burst detection approaches. We formulate this problem as a constraint satisfaction problem that has high computational complexity. To reduce the computational cost, we first reduce most of the constraints by making use of the fact that bursty cascades are rare among the whole population. We then transform the problem into an Linear Programming (LP) problem. Furthermore, we use the sub-gradient method instead of the standard simplex method or interior-point method to solve the LP problem, which makes it possible for our solution to scale up to large social networks. Evaluating our solution on millions of real information cascades, we demonstrate both the effectiveness and efficiency of our approach.","Title: A Noise-Robust Self-Adaptive Multitarget Speaker Detection System\nYear: 2018\n\nAbstract: We describe a multitarget speaker detection system that provides a robust way to classify the utterance of a speaker in noisy environments. The multitarget detection problem is known to be much more difficult to tackle than single target speaker verification tasks, especially when the target set is large and the data is corrupted by noise. In this work we aim to improve the performance of our multitarget speaker detection system in real-world settings, where complicated background noise and unpredictable speaker behavior are present. We make three major improvements that contribute to our goal. First, we discover an effective noise-filtering method using GMM-based voice activity detector followed by unsupervised bottom-up clustering. Second, we incorporate a Highway-LSTM network to estimate posterior distributions of senones, replacing the traditional GMM-UBM with senone posteriors. Finally, we apply a self-adaptive approach on the classifier back-end so that our PLDA parameters and S-normalization subsets can be updated online.","Title: Who Should Be Invited to My Party: A Size-Constrained k-Core Problem in Social Networks.\nYear: 2019\n\nAbstract: In this paper, we investigate the problem of a size-constrained k-core group query (SCCGQ) in social networks, taking both user closeness and network topology into consideration. More specifically, SCCGQ intends to find a group of h users that has the highest social closeness while being a k-core. SCCGQ can be widely applied to event planning, task assignment, social analysis, and many other fields. In contrast to existing work on the k-core detection problem, which aims to find a k-core in a social network, SCCGQ not only focuses on k-core detection but also takes size constraints into consideration. Although the conventional k-core detection problem can be solved in linear time, SCCGQ has a higher complexity. To solve the problem of SCCGQ, we propose a Blast Scatter (BS) algorithm, which appoints the query node as the center to begin outward expansions via breadth search. In each outward expansion, BS finds a new center through a greedy strategy and then selects multiple neighbors of the center. To speed up the BS algorithm, we propose an advanced search algorithm, called Bounded Extension (BE). Specifically, BE combines an effective social distance pruning strategy and a tight upper bound of social closeness to prune the search space considerably. In addition, we propose an offline social-aware index to accelerate the query processing. Finally, our experimental results demonstrate the efficiency and effectiveness of our proposed algorithms on large real-world social networks.","Title: Composer4Everyone: Automatic Music Generation with Audio Motif\nYear: 2019\n\nAbstract: We introduct Composer4Everyone, a wechat-based application that automatically generates music for a piece of audio recording. A user with little composition experience would also be able to create his own work by a simple interaction of humming, singing or even speaking. The input audio is taken as a motif and developed into a piece of piano music of 20-30 seconds. A rearranging system is provided for users to change the piano music into a different style.","Title: Dropout Regularization for Self-Supervised Learning of Transformer Encoder Speech Representation.\nYear: 2021\n\nAbstract: Predicting the altered acoustic frames is an effective way of self-supervised learning for speech representation. However, it is challenging to prevent the pretrained model from overfitting. In this paper, we proposed to introduce two dropout regularization methods into the pretraining of transformer encoder: (1) attention dropout, (2) layer dropout. Both of the two dropout methods encourage the model to utilize global speech information, and avoid just copying local spectrum features when reconstructing the masked frames. We evaluated the proposed methods on phoneme classification and speaker recognition tasks. The experiments demonstrate that our dropout approaches achieve competitive results, and improve the performance of classification accuracy on downstream tasks.","Title: Loss Prediction: End-to-End Active Learning Approach For Speech Recognition\nYear: 2021\n\nAbstract: End-to-end speech recognition systems usually require huge amounts of labeling resource, while annotating the speech data is complicated and expensive. Active learning is the solution by selecting the most valuable samples for annotation. In this paper, we proposed to use a predicted loss that estimates the uncertainty of the sample. The CTC (Connectionist Temporal Classification) and attention loss are informative for speech recognition since they are computed based on all decoding paths and alignments. We defined an end-to-end active learning pipeline, training an ASR/LP (Automatic Speech Recognition/Loss Prediction) joint model. The proposed approach was validated on an English and a Chinese speech recognition task. The experiments show that our approach achieves competitive results, outperforming random selection, least confidence, and estimated loss method.","Title: Variational Information Bottleneck for Effective Low-Resource Audio Classification.\nYear: 2021\n\nAbstract: Large-scale deep neural networks (DNNs) such as convolutional neural networks (CNNs) have achieved impressive performance in audio classification for their powerful capacity and strong generalization ability. However, when training a DNN model on low-resource tasks, it is usually prone to overfitting the small data and learning too much redundant information. To address this issue, we propose to use variational information bottleneck (VIB) to mitigate overfitting and suppress irrelevant information. In this work, we conduct experiments ona 4-layer CNN. However, the VIB framework is ready-to-use and could be easily utilized with many other state-of-the-art network architectures. Evaluation on a few audio datasets shows that our approach significantly outperforms baseline methods, yielding more than 5.0% improvement in terms of classification accuracy in some low-source settings.","Title: Speech2Video - Cross-Modal Distillation for Speech to Video Generation.\nYear: 2021\n\nAbstract: This paper investigates a novel task of talking face video generation solely from speeches. The speech-to-video generation technique can spark interesting applications in entertainment, customer service, and human-computer-interaction industries. Indeed, the timbre, accent and speed in speeches could contain rich information relevant to speakers' appearance. The challenge mainly lies in disentangling the distinct visual attributes from audio signals. In this article, we propose a light-weight, cross-modal distillation method to extract disentangled emotional and identity information from unlabelled video inputs. The extracted features are then integrated by a generative adversarial network into talking face video clips. With carefully crafted discriminators, the proposed framework achieves realistic generation results. Experiments with observed individuals demonstrated that the proposed framework captures the emotional expressions solely from speeches, and produces spontaneous facial motion in the video output. Compared to the baseline method where speeches are combined with a static image of the speaker, the results of the proposed framework is almost indistinguishable. User studies also show that the proposed method outperforms the existing algorithms in terms of emotion expression in the generated videos.","Title: Federated Learning with Dynamic Transformer for Text to Speech.\nYear: 2021\n\nAbstract: Text to speech (TTS) is a crucial task for user interaction, but TTS model training relies on a sizable set of high-quality original datasets. Due to privacy and security issues, the original datasets are usually unavailable directly. Recently, federated learning proposes a popular distributed machine learning paradigm with an enhanced privacy protection mechanism. It offers a practical and secure framework for data owners to collaborate with others, thus obtaining a better global model trained on the larger dataset. However, due to the high complexity of transformer models, the convergence process becomes slow and unstable in the federated learning setting. Besides, the transformer model trained in federated learning is costly communication and limited computational speed on clients, impeding its popularity. To deal with these challenges, we propose the federated dynamic transformer. On the one hand, the performance is greatly improved comparing with the federated transformer, approaching centralize-trained Transformer-TTS when increasing clients number. On the other hand, it achieves faster and more stable convergence in the training phase and significantly reduces communication time. Experiments on the LJSpeech dataset also strongly prove our method's advantage.","Title: Quantum Convolutional Neural Network on Protein Distance Prediction\nYear: 2021\n\nAbstract: Proteins are linear polymers that fold into an incredible variety of three-dimensional structures that enable sophisticated functionality for biology. Predicting protein distance with high precision remains challenging, particularly for small protein families. As deep learning achieves remarkable success in many areas, deep learning also allows scientists to predict proteins' three-dimensional structure. As convolutional neural networks have a powerful ability to learn data features at multiple levels of abstraction, we deploy CNN to predict protein distance. To accelerate the training process, we apply a quantum convolutional neural network(QCNN) to improve the protein structure prediction efficiently. For QCNN, the conventional convolutional layer is transformed to a quantum convolution or quanvolutional layer. Since the protein data has large input, we explore the large dimension of these quantum transformations. And in experiments, we compare the different number of layers in QCNN during the training phase. We found the QCNN is similar to CNN that is the deeper layer can get better performance. The simulations show the proposed method can accelerate the convergence while maintaining the performance.","Title: When Hearing the Voice, Who Will Come to Your Mind\nYear: 2021\n\nAbstract: Speech is a carrier containing rich biological information, such as speaker identity information including age, gender, race. In this paper, we explore the use of a self-supervised method to obtain speaker identity information from high-dimensional speech representations to generate face image. At the same time, considering that the biological information contained in the same piece of speech has different expression forms (such as images), we designed a cross-modal knowledge distillation method to transform the feature information from the visual domain to the speech domain. The feature vectors obtained through self-supervised learning and knowledge distillation are fed into a GAN-based generative model to obtain facial images containing speaker information. Subjective experiments show that our model can reach a well performance in the task of speaker identification. Experiments show that our proposed method can effectively establish the connection between different modalities and generate a face with rich biological information.","Title: Automatic Joint Optimization of Algorithm-Level Compression and Compiler-Based Acceleration with Reinforcement Learning for DNN in Edge Devices\nYear: 2021\n\nAbstract: More accurate machine learning models often require more memory cost and more software-hardware co-adaption efforts for deployments on resource-constrained devices. Model compression techniques and deep learning compiler are developed to reduce the memory cost and latency. However, current methods require tremendous engineering efforts to optimize the model manually. This paper introduces a jointly learning based framework to perform the compression task and the acceleration task simultaneously. The joint optimization method auto-tunes the algorithm-level compression and compiler-based acceleration with reinforcement learning. The experiment results demonstrate that we compress the model by a factor of 2 or 8, and accelerate the optimization up to 30 times using our learning framework.","Title: Enhancing Neural Architecture Search by Upgrading Weak Components\nYear: 2021\n\nAbstract: Neural Architecture Search (NAS) becomes increasingly popular due to the ability to liberate the researchers from the complicated model design. However, typical NAS methods search for high-quality networks at a substantial cost of time and resources. This work enhances the neural architecture search by upgrading the weak components of promising candidate networks. First, we define a search space stacked with repeated components, such as cells and blocks. Second, we propose an attention-wise component evaluation metric to score the components. Third, we exploit a novel search policy to discover weak and strong components in promising candidate networks. Lastly, we use strong components to replace weak components. Besides, to achieve higher accuracy with less time cost, we integrate two optimization schemes: knowledge transfer and self-ensemble. The knowledge transfer accelerates model training by integrating an attentive regularizer into the objective goal. And the self-ensemble method ensembles promising candidate networks as the teacher network to teach the student network. The experiment results demonstrate our method can achieve state-of-the-art results(97.48% accuracy on CIFAR-10 and 84.38% accuracy on CIFAR-100).","Title: Contrastive Learning for improving End-to-end Speaker Verification\nYear: 2021\n\nAbstract: Speaker verification involves examining the speech signal to authenticate the claim of a speaker as true or false. Deep neural networks are one of the successful implementations of complex non-linear models to learn unique and invariant features of data. They have been employed in speech recognition tasks and have shown their potential to be used for speaker recognition also. However, the overfitting problem is remained to prevent the model's performance. In this study, we apply contrastive learning on speaker verification tasks to solve the robustness problem. Besides, we introduce domain adaptive loss on the tasks. Experimental results and ablation study that indicate that our proposed model outperforms various baseline end-to-end methods significantly by at least relative 10%, including d-vector approaches, deep-speaker, and generalized end-to-end model, for text-dependent speaker verification on a company's internal text-dependent voice command DataSet.","Title: Diversified Point Cloud Classification Using Personalized Federated Learning\nYear: 2021\n\nAbstract: As a comprehensive and unstructured data source describing 3 dimensional (3D) objects, point cloud data has attracted wide interest from researchers. Neural networks (NNs) provide flexible, end-to-end solutions to point cloud processing tasks. Yet, one of the unavoidable problems in training the NNs is the difficulty in collecting and labeling high-quality point cloud data. Existing point cloud datasets are often collected at different scales and densities. Directly combining highly heterogeneous datasets might violate data protection regulations, but also lead to degradation of model performance. In our experiments, naive horizontal federated learning has been applied to alleviate the data privacy concern. However, when the datasets are not identically distributed, the federated model's performance falls far behind the state-of-the-art of centralized models. This paper investigates the union of highly heterogeneous point cloud datasets for the object classification task. In the proposed framework, the federated model is split into shared and personalized modules. The former improves generalizability by bringing multiple data sources into play, while the latter adapts local distribution and avoids convergence at false optima. Experiments show that the proposed framework FedPCN achieves 35.1% higher accuracy than FedAvg. At local test samples, FedPCN also outperforms the locally trained model by 0.5%.","Title: Transfer Ability of Monolingual Wav2vec2.0 for Low-resource Speech Recognition\nYear: 2021\n\nAbstract: Recently, there are several domains that have their own feature extractors, such as ResNet, BERT, and GPT-x, which are widely used for various down-stream tasks. These models are pre-trained on large amounts of unlabeled data by self-supervision. In the speech domain, wav2vec2.0 starts to show its powerful representation ability and feasibility for ultra-low resource speech recognition tasks. This speech feature extractor is pre-trained on the monolingual audiobook corpus, whereas it has not been thoroughly examined in real spoken scenarios and other languages. In this work, we endeavor to transfer the knowledge from the pre-trained monolingual wav2vec2.0 to cross-lingual spoken ASR tasks with less than 20 hours of labeled data. We achieve more than 20% relative improvements in all the six languages compared with previous methods, establishing a strong benchmark on CALLHOME datasets. Compared with supervised pre-training, self-supervision training used in wav2vec2.0 has a better transfer ability. We also find that using coarse-grained modeling units, such as subword or character, usually achieves better results than fine-grained modeling units, such as phone or letter.","Title: A Language Model Based Pseudo-Sample Deliberation for Semi-supervised Speech Recognition\nYear: 2021\n\nAbstract: End-to-end modeling requires tremendous amounts of transcribed speech to achieve an automatic speech recognition (ASR) model with high performance. For low-resource ASR tasks, it is a promising approach to utilize the highly accessible unlabeled speech and text corpus. Previous works have shown that training with pseudo samples, which are the inferring results given the unlabeled speech, can substantially improve the accuracy of a baseline ASR model. Besides the common data filtering to improve pseudo-label quality, we propose an alternative pseudo-sample deliberation method that operates on the output of the ASR model through a pre-trained bidirectional language model (BERT). It fixes the unreasonable tokens in the inference by substitution, which can distill knowledge from the large text corpus. Experiments on Librispeech show that assisted with our fixing operation, self-training on additional unlabeled samples can bridge up to 82.3% of the gap with the supervised training.","Title: Semantic Extraction for Sentence Representation via Reinforcement Learning\nYear: 2021\n\nAbstract: Many modern Natural Language Processing(NLP) systems rely on word embeddings, previously trained in an unsupervised manner on large corpora, as base features. Several attempts of learning unsupervised sentence representations have not achieved satisfactory performance and have not been widely adopted. In this work, we present a Semantic Extraction Reinforcement learning Model(SERM) for encoding sentences into embedding vectors, which transforms the learning process into intent detection and named entity recognition tasks. Intent detection is mainly related to the semantics of the whole sentence, while named entity recognition pays more attention to local entities. Given a sentence, SERM builds a sentence representation by extracting the most important words and removing irrelevant words in a sentence. Unlike the mainstream approach, SERM compresses sentences from semantic and entity perspectives and this allows us to efficiently learn different types of encoding functions. The experimental results show that SERM can learn high quality sentence representation. This paper demonstrates that our sentence representations have sufficient competitiveness with the best performing model on text classification task.","Title: CACnet: Cube Attentional CNN for Automatic Speech Recognition\nYear: 2021\n\nAbstract: End-to-end models have been widely used in Automatic Speech Recognition (ASR). Convolutional Neural Networks (CNNs) can effectively use spectrum information to model acoustic models. However, the convolution layers have limitations on the receptive field leading to restrictions for long speech signals. Inspired by this, we propose a Cube Attention CNN network(CACnet) that uses two different attention blocks to integrate the feature information of different dimensions for extending context information. Thereinto, the Global Deep Attention Block utilizes non-local operations to compute interactions between any two positions on feature maps and enables the acquirement of global feature representations while the Cross-Channel Attention Block adaptively recalibrates channel-wise feature responses. Then, outputs of the above two attention modules will be added up to further improve the feature representation which contributes to enrich contextual information. Finally, the performance of our proposed architecture will be explored under ASR tasks in English circumstances. Experiments on LibriSpeech indicate that CACnet achieves a word error rate (WER) of 3.78%/9.56% without language model (LM), and 2.84%/6.97% with LM, which is near state-of-the-art accuracy. CACnet on WSJ with 4.4% WER obtains better performance, compared to CTC-based CNN models, such as QuartzNet and Jasper, with the same language model. The proposed network achieves competitive accuracy while having fewer parameters. Moreover, CACnet can be easily incorporated into any existed network since it has the same input and output dimensions.","Title: Avqvc: One-Shot Voice Conversion By Vector Quantization With Applying Contrastive Learning.\nYear: 2022\n\nAbstract: Voice Conversion(VC) refers to changing the timbre of a speech while retaining the discourse content. Recently, many works have focused on disentangle-based learning techniques to separate the timbre and the linguistic content information from a speech signal. Once successful, voice conversion will be feasible and straightforward. This paper proposed a novel one-shot voice conversion framework based on vector quantization voice conversion (VQVC) and AutoVC, called AVQVC. A new training method is applied to VQVC to separate content and timbre information from speech more effectively. The result shows that this approach has better performance than VQVC in separating content and timbre to improve the sound quality of generated speech.","Title: nnSpeech: Speaker-Guided Conditional Variational Autoencoder for Zero-Shot Multi-speaker text-to-speech.\nYear: 2022\n\nAbstract: Multi-speaker text-to-speech (TTS) using a few adaption data is a challenge in practical applications. To address that, we propose a zero-shot multi-speaker TTS, named nnSpeech, that could synthesis a new speaker voice without fine-tuning and using only one adaption utterance. Compared with using a speaker representation module to extract the characteristics of new speakers, our method bases on a speaker-guided conditional variational autoencoder and can generate a variable Z, which contains both speaker characteristics and content information. The latent variable Z distribution is approximated by another variable conditioned on reference mel-spectrogram and phoneme. Experiments on the English corpus, Mandarin corpus, and cross-dataset proves that our model could generate natural and similar speech with only one adaption speech.","Title: VU-BERT: A Unified Framework for Visual Dialog.\nYear: 2022\n\nAbstract: The visual dialog task attempts to train an agent to answer multi-turn questions given an image, which requires the deep understanding of interactions between the image and dialog history. Existing researches tend to employ the modality-specific modules to model the interactions, which might be troublesome to use. To fill in this gap, we propose a unified framework for image-text joint embedding, named VU-BERT, and apply patch projection to obtain vision embedding firstly in visual dialog tasks to simplify the model. The model is trained over two tasks: masked language modeling and next utterance retrieval. These tasks help in learning visual concepts, utterances dependence, and the relationships between these two modalities. Finally, our VU-BERT achieves competitive performance (0.7287 NDCG scores) on VisDial v1.0 Datasets.","Title: DRVC: A Framework of Any-to-Any Voice Conversion with Self-Supervised Learning.\nYear: 2022\n\nAbstract: Any-to-any voice conversion problem aims to convert voices for source and target speakers, which are out of the training data. Previous works wildly utilize the disentangle-based models. The disentangle-based model assumes the speech consists of content and speaker style information and aims to untangle them to change the style information for conversion. Previous works focus on reducing the dimension of speech to get the content information. But the size is hard to determine to lead to the untangle overlapping problem. We propose the Disentangled Representation Voice Conversion (DRVC) model to address the issue. DRVC model is an end-to-end self-supervised model consisting of the content encoder, timbre encoder, and generator. Instead of the previous work for reducing speech size to get content, we propose a cycle for restricting the disentanglement by the Cycle Reconstruct Loss and Same Loss. The experiments show there is an improvement for converted speech on quality and voice similarity.","Title: RECONSTRUCTING DUAL LEARNING FOR NEURAL VOICE CONVERSION USING RELATIVELY FEW SAMPLES\nYear: 2021\n\nAbstract: This paper introduces a dual learning system for neural voice conversion (DualVC) using relatively few samples based on the symmetry of the speech conversion task. The system contains a pair of sequence-to-sequence neural networks that have the same structure but are trained in opposite directions. The objective function of the dual model training is the sum of paired conversion loss and reconstruction loss during the dual training circle. The models in the two directions are trained alternately to guide each other by the corresponding reconstruction loss. Furthermore, curriculum learning techniques are used to load models in existing fields into the current task to accelerate the rapid iteration and convergence of the model. The experiment on the voice conversion task with the proposed DualVC and curriculum learning strategy obtained a comparable naturalness and similarity with only a 30% dataset than the BaseVC model trained on the full dataset.","Title: TGAVC: IMPROVING AUTOENCODER VOICE CONVERSION WITH TEXT-GUIDED AND ADVERSARIAL TRAINING\nYear: 2021\n\nAbstract: Non-parallel many-to-many voice conversion remains an interesting but challenging speech processing task. Recently, AutoVC, a conditional autoencoder based method, achieved excellent conversion results by disentangling the speaker identity and the speech content using information-constraining bottlenecks. However, due to the pure autoencoder training method, it is difficult to evaluate the separation effect of content and speaker identity. In this paper, a novel voice conversion framework, named Text Guided AutoVC(TGAVC), is proposed to more effectively separate content and timbre from speech, where an expected content embedding produced based on the text transcriptions is designed to guide the extraction of voice content. In addition, the adversarial training is applied to eliminate the speaker identity information in the estimated content embedding extracted from speech. Under the guidance of the expected content embedding and the adversarial training, the content encoder is trained to extract speaker-independent content embedding from speech. Experiments on AIShell-3 dataset show that the proposed model outperforms AutoVC in terms of naturalness and similarity of converted speech.","Title: CYCLEGEAN: CYCLE GENERATIVE ENHANCED ADVERSARIAL NETWORK FOR VOICE CONVERSION\nYear: 2021\n\nAbstract: Cycle Generative Adversarial Network (CycleGAN) for voice conversion (VC) task only used discriminators to identify whether the input voice is generated or real. It means the confrontational does not check the similarity with the target voice, leading the generated voice not much similar to the target. In this paper, instead of vocal checking, we propose to enhance the confrontation to target similarity checking that addresses this problem. A Cycle Generative Enhanced Adversarial Network (CycleGEAN) was introduced to make the original two discriminators to target classifier and non-target classifier. The target classifier aims to identify whether the target speaks the input voice or not. Similarly, the non-target classifier identifies the non-target voice. Furthermore, we add a gradient reversal layer with different operations for target and non-target. Then in each GAN, we used both classifiers. One is the discriminator, and the other is trained for using in another GAN. In experiments, the proposed method compare to CycleGAN improves Mean Opinion Score (MOS) of 0.1 and Voice Similarity Score (VSS) of 0.2 on the Voice Conversion Challenge 2018 (VCC2018) dataset.","Title: r-G2P: Evaluating and Enhancing Robustness of Grapheme to Phoneme Conversion by Controlled Noise Introducing and Contextual Information Incorporation.\nYear: 2022\n\nAbstract: Grapheme-to-phoneme (G2P) conversion is the process of converting the written form of words to their pronunciations. It has an important role for text-to-speech (TTS) synthesis and automatic speech recognition (ASR) systems. In this paper, we aim to evaluate and enhance the robustness of G2P models. We show that neural G2P models are extremely sensitive to orthographical variations in graphemes like spelling mistakes. To solve this problem, we propose three controlled noise introducing methods to synthesize noisy training data. Moreover, we incorporate the contextual information with the baseline and propose a robust training strategy to stabilize the training process. The experimental results demonstrate that our proposed robust G2P model (r-G2P) outperforms the baseline significantly (-2.73\\% WER on Dict-based benchmarks and -9.09\\% WER on Real-world sources).","Title: Towards Speaker Age Estimation With Label Distribution Learning.\nYear: 2022\n\nAbstract: Existing methods for speaker age estimation usually treat it as a multi-class classification or a regression problem. However, precise age identification remains a challenge due to label ambiguity, \\emph{i.e.}, utterances from adjacent age of the same person are often indistinguishable. To address this, we utilize the ambiguous information among the age labels, convert each age label into a discrete label distribution and leverage the label distribution learning (LDL) method to fit the data. For each audio data sample, our method produces a age distribution of its speaker, and on top of the distribution we also perform two other tasks: age prediction and age uncertainty minimization. Therefore, our method naturally combines the age classification and regression approaches, which enhances the robustness of our method. We conduct experiments on the public NIST SRE08-10 dataset and a real-world dataset, which exhibit that our method outperforms baseline methods by a relatively large margin, yielding a 10\\% reduction in terms of mean absolute error (MAE) on a real-world dataset.","Title: Self-Attention for Incomplete Utterance Rewriting.\nYear: 2022\n\nAbstract: Incomplete utterance rewriting (IUR) has recently become an essential task in NLP, aiming to complement the incomplete utterance with sufficient context information for comprehension. In this paper, we propose a novel method by directly extracting the coreference and omission relationship from the self-attention weight matrix of the transformer instead of word embeddings and edit the original text accordingly to generate the complete utterance. Benefiting from the rich information in the self-attention weight matrix, our method achieved competitive results on public IUR datasets.","Title: Adaptive Few-Shot Learning Algorithm for Rare Sound Event Detection.\nYear: 2022\n\nAbstract: Sound event detection is to infer the event by understanding the surrounding environmental sounds. Due to the scarcity of rare sound events, it becomes challenging for the well-trained detectors which have learned too much prior knowledge. Meanwhile, few-shot learning methods promise a good generalization ability when facing a new limited-data task. Recent approaches have achieved promising results in this field. However, these approaches treat each support example independently, ignoring the information of other examples from the whole task. Because of this, most of previous methods are constrained to generate a same feature embedding for all test-time tasks, which is not adaptive to each inputted data. In this work, we propose a novel task-adaptive module which is easy to plant into any metric-based few-shot learning frameworks. The module could identify the task-relevant feature dimension. Incorporating our module improves the performance considerably on two datasets over baseline methods, especially for the transductive propagation network. Such as +6.8% for 5-way 1-shot accuracy on ESC-50, and +5.9% on noiseESC-50. We investigate our approach in the domain-mismatch setting and also achieve better results than previous methods.","Title: MetaSID: Singer Identification with Domain Adaptation for Metaverse.\nYear: 2022\n\nAbstract: Metaverse has stretched the real world into unlimited space. There will be more live concerts in Metaverse. The task of singer identification is to identify the song belongs to which singer. However, there has been a tough problem in singer identification, which is the different live effects. The studio version is different from the live version, the data distribution of the training set and the test set are different, and the performance of the classifier decreases. This paper proposes the use of the domain adaptation method to solve the live effect in singer identification. Three methods of domain adaptation combined with Convolutional Recurrent Neural Network (CRNN) are designed, which are Maximum Mean Discrepancy (MMD), gradient reversal (Revgrad), and Contrastive Adaptation Network (CAN). MMD is a distance-based method, which adds domain loss. Revgrad is based on the idea that learned features can represent different domain samples. CAN is based on class adaptation, it takes into account the correspondence between the categories of the source domain and target domain. Experimental results on the public dataset of Artist20 show that CRNN-MMD leads to an improvement over the baseline CRNN by 0.14. The CRNN-RevGrad outperforms the baseline by 0.21. The CRNN-CAN achieved state of the art with the F1 measure value of 0.83 on album split.","Title: Singer Identification for Metaverse with Timbral and Middle-Level Perceptual Features.\nYear: 2022\n\nAbstract: Metaverse is an interactive world that combines reality and virtuality, where participants can be virtual avatars. Anyone can hold a concert in a virtual concert hall, and users can quickly identify the real singer behind the virtual idol through the singer identification. Most singer identification methods are processed using the frame-level features. However, expect the singer's timbre, the music frame includes music information, such as melodiousness, rhythm, and tonal. It means the music information is noise for using frame-level features to identify the singers. In this paper, instead of only the frame-level features, we propose to use another two features that address this problem. Middle-level feature, which represents the music's melodiousness, rhythmic stability, and tonal stability, and is able to capture the perceptual features of music. The timbre feature, which is used in speaker identification, represents the singers' voice features. Furthermore, we propose a convolutional recurrent neural network (CRNN) to combine three features for singer identification. The model firstly fuses the frame-level feature and timbre feature and then combines middle-level features to the mix features. In experiments, the proposed method achieves comparable performance on an average F1 score of 0.81 on the benchmark dataset of Artist20, which significantly improves related works.","Title: TDASS: Target Domain Adaptation Speech Synthesis Framework for Multi-speaker Low-Resource TTS.\nYear: 2022\n\nAbstract: Recently, synthesizing personalized speech by text-to-speech (TTS) application is highly demanded. But the previous TTS models require a mass of target speaker speeches for training. It is a high-cost task, and hard to record lots of utterances from the target speaker. Data augmentation of the speeches is a solution but leads to the low-quality synthesis speech problem. Some multi-speaker TTS models are proposed to address the issue. But the quantity of utterances of each speaker imbalance leads to the voice similarity problem. We propose the Target Domain Adaptation Speech Synthesis Network (TDASS) to address these issues. Based on the backbone of the Tacotron2 model, which is the high-quality TTS model, TDASS introduces a self-interested classifier for reducing the non-target influence. Besides, a special gradient reversal layer with different operations for target and non-target is added to the classifier. We evaluate the model on a Chinese speech corpus, the experiments show the proposed method outperforms the baseline method in terms of voice quality and voice similarity.","Title: SUSing: SU-net for Singing Voice Synthesis.\nYear: 2022\n\nAbstract: Singing voice synthesis is a generative task that involves multi-dimensional control of the singing model, including lyrics, pitch, and duration, and includes the timbre of the singer and singing skills such as vibrato. In this paper, we proposed SU-net for singing voice synthesis named SUSing. Synthesizing singing voice is treated as a translation task between lyrics and music score and spectrum. The lyrics and music score information is encoded into a two-dimensional feature representation through the convolution layer. The two-dimensional feature and its frequency spectrum are mapped to the target spectrum in an autoregressive manner through a SU-net network. Within the SU-net the stripe pooling method is used to replace the alternate global pooling method to learn the vertical frequency relationship in the spectrum and the changes of frequency in the time domain. The experimental results on the public dataset Kiritan show that the proposed method can synthesize more natural singing voices.","Title: Improving Human Image Synthesis with Residual Fast Fourier Transformation and Wasserstein Distance\nYear: 2022\n\nAbstract: With the rapid development of the Metaverse, virtual humans have emerged, and human image synthesis and editing techniques, such as pose transfer, have recently become popular. Most of the existing techniques rely on GANs, which can generate good human images even with large variants and occlusions. But from our best knowledge, the existing state-of-the-art method still has the following problems: the first is that the rendering effect of the synthetic image is not realistic, such as poor rendering of some regions. And the second is that the training of GAN is unstable and slow to converge, such as model collapse. Based on the above two problems, we propose several methods to solve them. To improve the rendering effect, we use the Residual Fast Fourier Transform Block to replace the traditional Residual Block. Then, spectral normalization and Wasserstein distance are used to improve the speed and stability of GAN training. Experiments demonstrate that the methods we offer are effective at solving the problems listed above, and we get state-of-the-art scores in LPIPS and PSNR.","Title: Augmentation-induced Consistency Regularization for Classification\nYear: 2022\n\nAbstract: Deep neural networks have become popular in many supervised learning tasks, but they may suffer from overfitting when the training dataset is limited. To mitigate this, many researchers use data augmentation, which is a widely used and effective method for increasing the variety of datasets. However, the randomness introduced by data augmentation causes inevitable inconsistency between training and inference, which leads to poor improvement. In this paper, we propose a consistency regularization framework based on data augmentation, called CR-Aug, which forces the output distributions of different sub models generated by data augmentation to be consistent with each other. Specifically, CR-Aug evaluates the discrepancy between the output distributions of two augmented versions of each sample, and it utilizes a stop-gradient operation to minimize the consistency loss. We implement CR-Aug to image and audio classification tasks and conduct extensive experiments to verify its effectiveness in improving the generalization ability of classifiers. Our CR-Aug framework is ready-to-use, it can be easily adapted to many state-of-the-art network architectures. Our empirical results show that CR-Aug outperforms baseline methods by a significant margin.","Title: A Novel Capsule Aggregation Framework for Natural Language Inference\nYear: 2021\n\nAbstract: Recent advances have advocated the use of complex attention mechanism to capture interactive information between premise and hypothesis in Natural Language Inference (NLI). However, few studies have focused on the further processing of matching feature, i.e. information aggregation. In this paper, we first investigate a novel capsule network for NLI, referred as Gcap. Gcap utilizes a gated enhanced fusion operation to obtain richer features between massive soft alignment information. Then the capsule aggregates those features through routing algorithms. Benefit from the routing mechanism of the capsule network, Gcap can dynamically generate feature vectors for subsequent classifier. Evaluation results demonstrate that our model achieves accuracy of 89.1%, 88.2% and 79.6% (79.3%) on SNLI, SciTail and MultiNLI datasets respectively, which outperforms the strong baseline with gains of 0.2%, 1.4% and 0.3% (0.6%). In particular, we compare the runtime inference efficiency of BERT and our model. Our model can attain up to 33.3x speedup in online inference time. Thanks to dynamic aggregation, Gcap shows a strong ability to distinguish those cases that are easily confused.","Title: Self-supervised Learning for Semantic Sentence Matching with Dense Transformer Inference Network\nYear: 2021\n\nAbstract: Semantic sentence matching concerns predicting the relationship between a pair of natural language sentences. Recently, many methods based on interaction structure have been proposed, usually involving encoder, matching, and aggregation parts. Although some of them obtain impressive results, the simple encoder training from scratch cannot extract the global features of sentences effectively, and the transmission of information in the stacked network will cause certain loss. In this paper, we propose a Densely-connected Inference-Attention network (DCIA) to maximize the use of the feature from each layer of the network by dense connection mechanism and to get robust encoder by self-supervised learning (SSL) based on contrastive method, which can maximize the mutual information between global features and local features of input data. We have conducted experiments on Quora, MRPC, and SICK dataset, the experimental results show that our method owns competitive results on these dataset where we drive 89.13%, 78.1% and 87.7% accuracies respectively. In addition, the accuracy of DCIA with SSL will surpass the one of DCIA without SSL by about 2%.","Title: Cali3F: Calibrated Fast Fair Federated Recommendation System.\nYear: 2022\n\nAbstract: The increasingly stringent regulations on privacy protection have sparked interest in federated learning. As a distributed machine learning framework, it bridges isolated data islands by training a global model over devices while keeping data localized. Specific to recommendation systems, many federated recommendation algorithms have been proposed to realize the privacy-preserving collaborative recommendation. However, several constraints remain largely unexplored. One big concern is how to ensure fairness between participants of federated learning, that is, to maintain the uniformity of recommendation performance across devices. On the other hand, due to data heterogeneity and limited networks, additional challenges occur in the convergence speed. To address these problems, in this paper, we first propose a personalized federated recommendation system training algorithm to improve the recommendation performance fairness. Then we adopt a clustering-based aggregation method to accelerate the training process. Combining the two components, we proposed Cali3F, a calibrated fast and fair federated recommendation framework. Cali3F not only addresses the convergence problem by a within-cluster parameter sharing approach but also significantly boosts fairness by calibrating local models with the global model. We demonstrate the performance of Cali3F across standard benchmark datasets and explore the efficacy in comparison to traditional aggregation approaches.","Title: QSpeech: Low-Qubit Quantum Speech Application Toolkit\nYear: 2022\n\nAbstract: Quantum devices with low qubits are common in the Noisy Intermediate-Scale Quantum (NISQ) era. However, Quantum Neural Network (QNN) running on low-qubit quantum devices would be difficult since it is based on Variational Quantum Circuit (VQC), which requires many qubits. Therefore, it is critical to make QNN with VQC run on low-qubit quantum devices. In this study, we propose a novel VQC called the low-qubit VQC. VQC requires numerous qubits based on the input dimension; however, the low-qubit VQC with linear transformation can liberate this condition. Thus, it allows the QNN to run on low-qubit quantum devices for speech applications. Furthermore, as compared to the VQC, our proposed low-qubit VQC can stabilize the training process more. Based on the low-qubit VQC, we implement QSpeech, a library for quick prototyping of hybrid quantum-classical neural networks in the speech field. It has numerous quantum neural layers and QNN models for speech applications. Experiments on Speech Command Recognition and Text-to-Speech show that our proposed low-qubit VQC outperforms VQC and is more stable.","Title: DT-SV: A Transformer-based Time-domain Approach for Speaker Verification.\nYear: 2022\n\nAbstract: Speaker verification (SV) aims to determine whether the speaker's identity of a test utterance is the same as the reference speech. In the past few years, extracting speaker embeddings using deep neural networks for SV systems has gone mainstream. Recently, different attention mechanisms and Transformer networks have been explored widely in SV fields. However, utilizing the original Transformer in SV directly may have frame-level information waste on output features, which could lead to restrictions on capacity and discrimination of speaker embeddings. Therefore, we propose an approach to derive utterance-level speaker embeddings via a Transformer architecture that uses a novel loss function named diffluence loss to integrate the feature information of different Transformer layers. Therein, the diffluence loss aims to aggregate frame-level features into an utterance-level representation, and it could be integrated into the Transformer expediently. Besides, we also introduce a learnable mel-fbank energy feature extractor named time-domain feature extractor that computes the mel-fbank features more precisely and efficiently than the standard mel-fbank extractor. Combining Diffluence loss and Time-domain feature extractor, we propose a novel Transformer-based time-domain SV model (DT-SV) with faster training speed and higher accuracy. Experiments indicate that our proposed model can achieve better performance in comparison with other models.","Title: Federated Split BERT for Heterogeneous Text Classification\nYear: 2022\n\nAbstract: Pre-trained BERT models have achieved impressive performance in many natural language processing (NLP) tasks. However, in many real-world situations, textual data are usually decentralized over many clients and unable to be uploaded to a central server due to privacy protection and regulations. Federated learning (FL) enables multiple clients collaboratively to train a global model while keeping the local data privacy. A few researches have investigated BERT in federated learning setting, but the problem of performance loss caused by heterogeneous (e.g., non-IID) data over clients remain under-explored. To address this issue, we propose a framework, FedSplitBERT, which handles heterogeneous data and decreases the communication cost by splitting the BERT encoder layers into local part and global part. The local part parameters are trained by the local client only while the global part parameters are trained by aggregating gradients of multiple clients. Due to the sheer size of BERT, we explore a quantization method to further reduce the communication cost with minimal performance loss. Our framework is ready-to-use and compatible to many existing federated learning algorithms, including FedAvg, FedProx and FedAdam. Our experiments verify the effectiveness of the proposed framework, which outperforms baseline methods by a significant margin, while FedSplitBERT with quantization can reduce the communication cost by $11.9\\times$.","Title: Federated Non-negative Matrix Factorization for Short Texts Topic Modeling with Mutual Information\nYear: 2022\n\nAbstract: Non-negative matrix factorization (NMF) based topic modeling is widely used in natural language processing (NLP) to uncover hidden topics of short text documents. Usually, training a high-quality topic model requires large amount of textual data. In many real-world scenarios, customer textual data should be private and sensitive, precluding uploading to data centers. This paper proposes a Federated NMF (FedNMF) framework, which allows multiple clients to collaboratively train a high-quality NMF based topic model with locally stored data. However, standard federated learning will significantly undermine the performance of topic models in downstream tasks (e.g., text classification) when the data distribution over clients is heterogeneous. To alleviate this issue, we further propose FedNMF+MI, which simultaneously maximizes the mutual information (MI) between the count features of local texts and their topic weight vectors to mitigate the performance degradation. Experimental results show that our FedNMF+MI methods outperform Federated Latent Dirichlet Allocation (FedLDA) and the FedNMF without MI methods for short texts by a significant margin on both coherence score and classification F1 score.","Title: Leveraging Causal Inference for Explainable Automatic Program Repair\nYear: 2022\n\nAbstract: Deep learning models have made significant progress in automatic program repair. However, the black-box nature of these methods has restricted their practical applications. To address this challenge, this paper presents an interpretable approach for program repair based on sequence-to-sequence models with causal inference and our method is called CPR, short for causal program repair. Our CPR can generate explanations in the process of decision making, which consists of groups of causally related input-output tokens. Firstly, our method infers these relations by querying the model with inputs disturbed by data augmentation. Secondly, it generates a graph over tokens from the responses and solves a partitioning problem to select the most relevant components. The experiments on four programming languages (Java, C, Python, and JavaScript) show that CPR can generate causal graphs for reasonable interpretations and boost the performance of bug fixing in automatic program repair.","Title: A Fair Federated Learning Framework With Reinforcement Learning\nYear: 2022\n\nAbstract: Federated learning (FL) is a paradigm where many clients collaboratively train a model under the coordination of a central server, while keeping the training data locally stored. However, heterogeneous data distributions over different clients remain a challenge to mainstream FL algorithms, which may cause slow convergence, overall performance degradation and unfairness of performance across clients. To address these problems, in this study we propose a reinforcement learning framework, called PG-FFL, which automatically learns a policy to assign aggregation weights to clients. Additionally, we propose to utilize Gini coefficient as the measure of fairness for FL. More importantly, we apply the Gini coefficient and validation accuracy of clients in each communication round to construct a reward function for the reinforcement learning. Our PG-FFL is also compatible to many existing FL algorithms. We conduct extensive experiments over diverse datasets to verify the effectiveness of our framework. The experimental results show that our framework can outperform baseline methods in terms of overall performance, fairness and convergence speed.","Title: Adaptive Activation Network for Low Resource Multilingual Speech Recognition\nYear: 2022\n\nAbstract: Low resource automatic speech recognition (ASR) is a useful but thorny task, since deep learning ASR models usually need huge amounts of training data. The existing models mostly established a bottleneck (BN) layer by pre-training on a large source language, and transferring to the low resource target language. In this work, we introduced an adaptive activation network to the upper layers of ASR model, and applied different activation functions to different languages. We also proposed two approaches to train the model: (1) cross-lingual learning, replacing the activation function from source language to target language, (2) multilingual learning, jointly training the Connectionist Temporal Classification (CTC) loss of each language and the relevance of different languages. Our experiments on IARPA Babel datasets demonstrated that our approaches outperform the from-scratch training and traditional bottleneck feature based methods. In addition, combining the cross-lingual learning and multilingual learning together could further improve the performance of multilingual speech recognition.","Title: Speech Augmentation Based Unsupervised Learning for Keyword Spotting\nYear: 2022\n\nAbstract: In this paper, we investigated a speech augmentation based unsupervised learning approach for keyword spotting (KWS) task. KWS is a useful speech application, yet also heavily depends on the labeled data. We designed a CNN-Attention architecture to conduct the KWS task. CNN layers focus on the local acoustic features, and attention layers model the long-time dependency. To improve the robustness of KWS model, we also proposed an unsupervised learning method. The unsupervised loss is based on the similarity between the original and augmented speech features, as well as the audio reconstructing information. Two speech augmentation methods are explored in the unsupervised learning: speed and intensity. The experiments on Google Speech Commands V2 Dataset demonstrated that our CNN-Attention model has competitive results. Moreover, the augmentation based unsupervised learning could further improve the classification accuracy of KWS task. In our experiments, with augmentation based unsupervised learning, our KWS model achieves better performance than other unsupervised methods, such as CPC, APC, and MPC.","Title: Micro-Expression Recognition Based on Attribute Information Embedding and Cross-modal Contrastive Learning\nYear: 2022\n\nAbstract: Facial micro-expressions recognition has attracted much attention recently. Micro-expressions have the characteristics of short duration and low intensity, and it is difficult to train a high-performance classifier with the limited number of existing micro-expressions. Therefore, recognizing micro-expressions is a challenge task. In this paper, we propose a micro-expression recognition method based on attribute information embedding and cross-modal contrastive learning. We use 3D CNN to extract RGB features and FLOW features of micro-expression sequences and fuse them, and use BERT network to extract text information in Facial Action Coding System. Through cross-modal contrastive loss, we embed attribute information in the visual network, thereby improving the representation ability of micro-expression recognition in the case of limited samples. We conduct extensive experiments in CASME II and MMEW databases, and the accuracy is 77.82% and 71.04%, respectively. The comparative experiments show that this method has better recognition effect than other methods for micro-expression recognition.","Title: A Privacy-Preserving Subgraph-Level Federated Graph Neural Network via Differential Privacy.\nYear: 2022\n\nAbstract: Currently, the federated graph neural network (GNN) has attracted a lot of attention due to its wide applications in reality without violating the privacy regulations. Among all the privacy-preserving technologies, the differential privacy (DP) is the most promising one due to its effectiveness and light computational overhead. However, the DP-based federated GNN has not been well investigated, especially in the sub-graph-level setting, such as the scenario of recommendation system. The biggest challenge is how to guarantee the privacy and solve the non independent and identically distributed (non-IID) data in federated GNN simultaneously. In this paper, we propose DP-FedRec, a DP-based federated GNN to fill the gap. Private Set Intersection (PSI) is leveraged to extend the local graph for each client, and thus solve the non-IID problem. Most importantly, DP is applied not only on the weights but also on the edges of the intersection graph from PSI to fully protect the privacy of clients. The evaluation demonstrates DP-FedRec achieves better performance with the graph extension and DP only introduces little computations overhead.","Title: Uncertainty Calibration for Deep Audio Classifiers.\nYear: 2022\n\nAbstract: Although deep Neural Networks (DNNs) have achieved tremendous success in audio classification tasks, their uncertainty calibration are still under-explored. A well-calibrated model should be accurate when it is certain about its prediction and indicate high uncertainty when it is likely to be inaccurate. In this work, we investigate the uncertainty calibration for deep audio classifiers. In particular, we empirically study the performance of popular calibration methods: (i) Monte Carlo Dropout, (ii) ensemble, (iii) focal loss, and (iv) spectral-normalized Gaussian process (SNGP), on audio classification datasets. To this end, we evaluate (i-iv) for the tasks of environment sound and music genre classification. Results indicate that uncalibrated deep audio classifiers may be over-confident, and SNGP performs the best and is very efficient on the two datasets of this paper.","Title: SpeechEQ: Speech Emotion Recognition based on Multi-scale Unified Datasets and Multitask Learning\nYear: 2022\n\nAbstract: Speech emotion recognition (SER) has many challenges, but one of the main challenges is that each framework does not have a unified standard. In this paper, we propose SpeechEQ, a framework for unifying SER tasks based on a multi-scale unified metric. This metric can be trained by Multitask Learning (MTL), which includes two emotion recognition tasks of Emotion States Category (EIS) and Emotion Intensity Scale (EIS), and two auxiliary tasks of phoneme recognition and gender recognition. For this framework, we build a Mandarin SER dataset - SpeechEQ Dataset (SEQD). We conducted experiments on the public CASIA and ESD datasets in Mandarin, which exhibit that our method outperforms baseline methods by a relatively large margin, yielding 8.0% and 6.5% improvement in accuracy respectively. Additional experiments on IEMOCAP with four emotion categories (i.e., angry, happy, sad, and neutral) also show the proposed method achieves a state-of-the-art of both weighted accuracy (WA) of 78.16% and unweighted accuracy (UA) of 77.47%.","Title: Tiny-Sepformer: A Tiny Time-Domain Transformer Network For Speech Separation\nYear: 2022\n\nAbstract: Time-domain Transformer neural networks have proven their superiority in speech separation tasks. However, these models usually have a large number of network parameters, thus often encountering the problem of GPU memory explosion. In this paper, we proposed Tiny-Sepformer, a tiny version of Transformer network for speech separation. We present two techniques to reduce the model parameters and memory consumption: (1) Convolution-Attention (CA) block, spliting the vanilla Transformer to two paths, multi-head attention and 1D depthwise separable convolution, (2) parameter sharing, sharing the layer parameters within the CA block. In our experiments, Tiny-Sepformer could greatly reduce the model size, and achieves comparable separation performance with vanilla Sepformer on WSJ0-2/3Mix datasets.","Title: Speech Representation Disentanglement with Adversarial Mutual Information Learning for One-shot Voice Conversion.\nYear: 2022\n\nAbstract: One-shot voice conversion (VC) with only a single target speaker's speech for reference has become a hot research topic. Existing works generally disentangle timbre, while information about pitch, rhythm and content is still mixed together. To perform one-shot VC effectively with further disentangling these speech components, we employ random resampling for pitch and content encoder and use the variational contrastive log-ratio upper bound of mutual information and gradient reversal layer based adversarial mutual information learning to ensure the different parts of the latent space containing only the desired disentangled representation during training. Experiments on the VCTK dataset show the model achieves state-of-the-art performance for one-shot VC in terms of naturalness and intellgibility. In addition, we can transfer characteristics of one-shot VC on timbre, pitch and rhythm separately by speech representation disentanglement. Our code, pre-trained models and demo are available at https://im1eon.github.io/IS2022-SRDVC/.","Title: Debias the Black-Box: A Fair Ranking Framework via Knowledge Distillation.\nYear: 2022\n\nAbstract: Deep neural networks can capture the intricate interaction history information between queries and documents, because of their many complicated nonlinear units, allowing them to provide correct search recommendations. However, service providers frequently face more complex obstacles in real-world circumstances, such as deployment cost constraints and fairness requirements. Knowledge distillation, which transfers the knowledge of a well-trained complex model (teacher) to a simple model (student), has been proposed to alleviate the former concern, but the best current distillation methods focus only on how to make the student model imitate the predictions of the teacher model. To better facilitate the application of deep models, we propose a fair information retrieval framework based on knowledge distillation. This framework can improve the exposure-based fairness of models while considerably decreasing model size. Our extensive experiments on three huge datasets show that our proposed framework can reduce the model size to a minimum of 1% of its original size while maintaining its black-box state. It also improves fairness performance by 15%~46% while keeping a high level of recommendation effectiveness.","Title: A Nearest Neighbor Under-sampling Strategy for Vertical Federated Learning in Financial Domain\nYear: 2022\n\nAbstract: BSTRACTMachine learning techniques have been widely applied in modern financial activities. Participants in the field are aware of the importance of data privacy. Vertical federated learning (VFL) was proposed as a solution to multi-party secure computation for machine learning to obtain the huge data required by the models as well as keep the privacy of the data holders. However, previous research majorly analyzed the algorithms under ideal conditions. Data imbalance in VFL is still an open problem. In this paper, we propose a privacy-preserving sampling strategy for imbalanced VFL based on federated graph embedding of the samples, without leaking any distribution information. The participants of the federation provide partial neighbor information for each sample during the intersection stage and the controversial negative sample will be filtered out. Experiments were conducted on commonly used financial datasets and one real-world dataset. Our proposed approach obtained the leading F1 score on all tested datasets on comparing with the baseline under sampling strategies for VFL."],"string":"[\n \"Title: Avoiding performance fluctuation in cloud storage\\nYear: 2010\\n\\nAbstract: Cloud computing is an elastic computing model whereby users can lease computing and storage resources on demand from a remote infrastructure. Cloud computing is gaining popularity due to its low cost, high reliability and wide availability. However, a serious impediment to its wider deployment is the relative lack of effective data management services. The relatively slow access to persistent data and large variability in cloud storage I/O performance, can significantly degrade the performance of data-intensive applications. This paper addresses the problem of I/O performance fluctuation and proposes an automatic optimization schema for cloud storage called AOSC, which utilizes data chunking, placement, and replication to achieve more stable and predictable performance. Our experimental results based on Amazon Elastic Cloud Computing (EC2) data center show that AOSC can improve the stability and help provide better performance guarantees for cloud computing.\",\n \"Title: Reducing Storage Overhead with Small Write Bottleneck Avoiding in Cloud RAID System\\nYear: 2012\\n\\nAbstract: Cloud storage systems commonly use replication of stored data sets to ensure high reliability and availability. However, the high storage overhead of replication becomes increasingly unacceptable with the explosive growth of data stored in cloud. Some cloud storage systems have attempted to replace replication with erasure coding to reduce storage overhead, that is just the thinking behind Cloud RAID. A well-designed Cloud RAID mechanism should achieve the right tradeoffs between storage efficiency, performance, and reliability. As there exists no widely-accepted methods for Cloud RAID, we present a workloads-based Cloud RAID schema-Selective Cloud RAID (SCR for short). SCR treats primary storage and backup storage with different RAIDmethods, the former at the level of directories, and the latter at the level of individual files. SCR has three distinct advantages over previous attempts at Cloud RAID: (1) it can significantly reduce the storage overhead compared with threeway replication, (2) it can avoid most cases of the \\\"small write bottleneck\\\" and simplify system maintenance, (3) its implementation is modular, therefore, it is easy to configure different erasure codes for different workloads. Additionally, we have implemented a SCR prototype with RDP code, which shows significant benefits over Blaum-Roth codes in degraded read performance. To verify the effectiveness of SCR, we perform theoretical analysis and elaborate benchmark tests to evaluate the performance of SCR prototype.\",\n \"Title: RO-BURST: A Robust Virtualization Cost Model for Workload Consolidation over Clouds\\nYear: 2012\\n\\nAbstract: As more public cloud computing platforms are emerging in the market, a great challenge for these Infrastructure as a Server (IaaS) providers is how to measure the cost and charge the Software as a Service (SaaS) clients for the cloud computing services. This problem is compounded as virtualization technology is deployed in many cloud platforms to consolidate servers and improve their utilization. This paper studies three different but related models for apportioning costs in a private or public cloud environment supported by virtualized data centers. With given workload placement scenarios and randomly selected workloads, these models estimate the cost for each workload. Through simulations and thorough comparisons of the results, we finally champion the RO-BURST model tailored for the service providers' need, that is characterized by robustness and burstiness. What is more, we import Cost Volatility Factors to ensure that our model is able to adjust itself to the market and multiform demands in power and hardware components, such as disks and CPU, showing its compatibility and extensibility. We also come up with a pricing strategy with respect to servers the workload employs, which generates an applicable and less placement-sensitive fee for the clients.\",\n \"Title: Robot: An efficient model for big data storage systems based on erasure coding\\nYear: 2013\\n\\nAbstract: It is well-known that with the explosive growth of data, the age of big data has arrived. How to save huge amounts of data is of great importance to both industry and academia. This paper puts forward a solution based on coding technologies in big data system that store a lot of cold data. By studying existing coding technologies and big data systems, we can not only maintain the system's reliability, but also improve the security and the utilization of storage systems. Due to the remarkable reliability and space saving rate of coding technologies, importing coding schema in to big data systems becomes prerequisite. In our presented schema, the storage node is divided into several virtual nodes to keep load balancing. By setting up different virtual node storage groups for different codec server, we can ensure system availability. And by utilizing the parallel decoding computing of the node and the block of data, we can also reduce the system recovery time when data is corrupted. Additionally, different users set different coding parameters can improve the robustness of big data storage systems. We configure various data block m and calibration block k to improve the utilization rate in the quantitative experiments. The results shows that parallel decoding speed can rise up two times than the past serial decoding speed. The encoding efficiency with ICRS coding is 34.2% higher than using CRS and 56.5% more than using RS coding equally. The decoding rate by using ICRS is 18.1% higher than using CRS and 31.1% higher than using RS averagely.\",\n \"Title: pCloud: an adaptive i/o resource allocation algorithm with revenue consideration over public clouds\\nYear: 2012\\n\\nAbstract: Cloud-based services are emerging as an economical and convenient alternative for clients who don't want to acquire, maintain and operate their own IT equipment. Instead, customers purchase virtual machines (VMs) with certain Service Level Objectives (SLOs) to obtain computational resources. Existing algorithms for memory and CPU allocation are inadequate for I/O allocation, especially in clustered storage infrastructures where storage is distributed across multiple storage nodes. This paper focuses on: (1) dynamic SLO decomposition so VMs receive proper I/O service in each distributed storage node, and (2) efficient and robust local I/O scheduling strategy. To address these issues, we present pCloud, an adaptive I/O resource allocation algorithm that at runtime adjusts local SLOs. The local SLOs are generated for each VM at each storage node based on access patterns. We also adopt dual clocks in pCloud to allow automatic switching between two scheduling strategies. When system capacity is sufficient, pCloud interweaves requests in an earliest deadline first (EDF) manner. Otherwise resources are allocated proportionate to their normalized revenues. The results of our experiments suggest that pCloud is adaptive to various access patterns without significant manual pre-settings while maximizing profits.\",\n \"Title: Data Mining of Mass Storage Based on Cloud Computing\\nYear: 2010\\n\\nAbstract: Cloud computing is an elastic computing model that the users can lease the resources from the rentable infrastructure. Cloud computing is gaining popularity due to its lower cost, high reliability and huge availability. To utilize the powerful and huge capability of cloud computing, this paper is to import it into data mining and machine learning field. As one of the most influential and open competition in machine learning area, Netflix Prize attached with mass storage had driven thousands of teams across the world to attack the problem, among which the final winner was BellKor's Pragmatic Chaos team, who bested Netflix's own algorithm for predicting ratings by 10%. Their solution is an ensemble of a large number of models, each of which specializes in addressing a different aspect of the data. Among such different models, k-nearest neighbors (KNN) and Restricted Boltzmann Machine (RBM) are reported to be two most important and successful models. As a result, we build two predictors based on such two model respectively with the order to testify their performance based on cloud computing platforms. The results show that KNN can achieve root mean square deviation (rmse) with 0:9468 after the Global Effect (GE) data preprocessing, which is better than the Cinematch's performance with rmse being 0:951. The rmse for RBM algorithm is about 0:9670 on the raw dataset, which can be further improved by KNN model.\",\n \"Title: TRACER: A Trace Replay Tool to Evaluate Energy-Efficiency of Mass Storage Systems\\nYear: 2010\\n\\nAbstract: Improving energy efficiency of mass storage systems has become an important and pressing research issue in large HPC centers and data centers. New energy conservation techniques in storage systems constantly spring up; however, there is a lack of systematic and uniform way of accurately evaluating energy-efficient storage systems and objectively comparing a wide range of energy-saving techniques. This research presents a new integrated scheme, called TRACER, for evaluating energy-efficiency of mass storage systems and judging energy-saving techniques. The TRACER scheme consists of a toolkit used to measure energy efficiency of storage systems as well as performance and energy metrics. In addition, TRACER contains a novel and accurate workload-control module to acquire power varying with workload modes and I/O load intensity. The workload generator in TRACER facilitates a block-level trace replay mechanism. The main goal of the workload-control module is to select a certain percentage (e.g., anywhere from 10% to 100%) of trace entries from a real-world I/O trace file uniformly and to replay filtered trace entries to reach any level of I/O load intensity. TRACER is experimentally validated on a general RAID5 enterprise disk array. Our experiments demonstrate that energy-efficient mass storage systems can be accurately evaluated on full scales by TRACER. We applied TRACER to investigate impacts of workload modes and load intensity on energy-efficiency of storage devices. This work shows that TRACER can enable storage system developers to evaluate energy efficiency designs for storage systems.\",\n \"Title: A Quantitative Evaluation Model for Choosing Efficient Redundancy Strategies over Clouds\\nYear: 2012\\n\\nAbstract: Reliability has always been one of the key issues that draw widespread concerns since the rise of cloud computing. While most cloud systems use replication to ensure high reliability, some scholars incline to try erasure codes in the interest of space efficiency. Comparison of performance and reliability between replication and erasure coding have been widely analyzed by many researchers, but effort to make a thorough understanding of this issue is quite few. In this paper, we defined a quantitative model aimed at comprehensively evaluating the relative merits of the two redundancy schemes in seven metrics (availability, reliability, storage, performance, bandwidth, energy and dollar cost) which will be detailed next, and we exploited this model to provide a reference for Cloud Service Providers (CSPs for short) to set up the right configurations for their cloud file systems. In addition, we presented a scheme to decide on which one of the two redundancy schemes more suitable for a given cloud storage system.\",\n \"Title: Enhancing shared RAID performance through online profiling\\nYear: 2012\\n\\nAbstract: Enterprise storage systems are generally shared by multiple servers in a SAN environment. Our experiments as well as industry reports have shown that disk arrays show poor performance when multiple servers share one RAID due to resource contention as well as frequent disk head movements. We have studied IO performance characteristics of several shared storage settings of practical business operations. To avoid the IO contention, we propose a new dynamic data relocation technique on shared RAID storages, referred to as DROP, Dynamic data Relocation to Optimize Performance. DROP allocates/manages a group of cache data areas and relocates/drops the portion of hot data at a predefined sub array that is a physical partition on the top of the entire shared array. By analyzing profiling data to make each cache area owned by one server, we are able to determine optimal data relocation and partition of disks in the RAID to maximize large sequential block accesses on individual disks and at the same time maximize parallel accesses across disks in the array. As a result, DROP minimizes disk head movements in the array at run time giving rise to high IO performance. A prototype DROP has been implemented as a software module at the storage target controller. Extensive experiments have been carried out using real world IO workloads to evaluate the performance of the DROP implementation. Experimental results have shown that DROP improves shared IO performance greatly. The performance improvements in terms of average IO response time range from 20% to a factor 2.5 at no additional hardware cost.\",\n \"Title: A Fine-Grained Data Reconstruction Algorithm for Solid-State Disks\\nYear: 2010\\n\\nAbstract: Solid-state disks (SSDs) with high I/O performance are increasingly becoming popular. To extend the life time of flash memory, one can apply wear-leveling strategies to manage data blocks. However, wear-leveling strategies certainly inevitably degrade write performance. In addition to low write performance, wear-leveling strategies make one block unwritable when one bit of this block is invalid. Although data reconstruction techniques have been widely employed in disk arrays, the reconstruction techniques has not been studied in the context of solid-state disks. In this paper, we present a new fine-grained data-reconstruction algorithm for solid-state disks. The algorithm aims to provide a simple yet efficient wear-leveling strategy that improves both I/O performance and reliability of solid-state disks. Simulation experiments show that all data blocks have very similar in terms of erasure times. The number of extra erasures incurred by our algorithm is very marginal.\",\n \"Title: C-IRR: An Adaptive Engine for Cloud Storage Provisioning Determined by Economic Models with Workload Burstiness Consideration\\nYear: 2012\\n\\nAbstract: Being the long dreamed vision of computing as a utility, cloud enables convenient and on-demand access to a large centralized pool of resources via network. The emerging of cloud storage offers a rather feasible solution to handle the sheer amount of information. It is maturing and becoming an alternative for on-premise storage. Thus, for IT enterprises with high demand of storage, a big concern is to determine whether it is more cost-effective to lease storage service over clouds. In this paper, we introduce a cloud storage provisioning engine called C-IRR to help users rationally evaluate the benefits of purchasing new disk drives and comparing it against leasing cloud storage offered by Infrastructure as a service (IaaS) providers. We also discuss issues regarding workload burstiness to achieve potential benefit for each applications in local data centers of SaaS providers. The C-IRR migrates the bursty workloads to the clouds and keeps stable ones locally. Such hybrid storage method achieves at least 20% costs saving in total for SaaS companies by experimental evaluation. In addition, C-IRR engine is of adaptivity about fluctuation of storage pricing and manpower cost increasing after the sensitivity studying.\",\n \"Title: Middleware enabled data sharing on cloud storage services.\\nYear: 2010\\n\\nAbstract: With the emergence of public cloud storage platforms like Amazon, Microsoft and Google etc, individual applications and some enterprise storage are being increasingly deployed on Clouds. However, dynamic data sharing in public clouds face problems of low performance and lack of SLA guarantees. We propose a middleware called mCloud between the Cloud storage and clients to provide data sharing services with better performance and SLA satisfaction. Technologies including virtualization, chunking, and caching, are integrated into mCloud. Experiential results based on Amazon Web Services (AWS) have shown that mCloud is able to improve shared IO performance in term of aggregate IO throughput and help provide better SLAs for cloud storage.\",\n \"Title: qSDS: A QoS-Aware I/O Scheduling Framework towards Software Defined Storage\\nYear: 2015\\n\\nAbstract: The inadequate resource allocation, lack of I/O performance prediction and insufficient I/O isolation are affecting the storage performance in the multi-tenant cloud storage environment. For Quality of Service (QoS), the Software-defined Storage (SDS) is an effective approach in data centers. However, the lack of intelligence, robustness and self-adjustment are blocking the applications and promotions of SDS heavily. This paper focuses on the QoS-Aware I/O resource scheduling problem to build data centers with high avail- ability, scalability and QoS. We will study workload characteristics, requirement analysis, the theory of QoS in SDS and I/O scheduling strategies. We obtain such goals by proposing a mathematics model of workload burstness, QoS semantic description with rule execution mechanisms and dynamic robust I/O scheduling algorithms for multi-type resources allocation. In the current progress, A QoS-Aware I/O Scheduling Framework towards SDS, qSDS has been proposed for the SSD/HDD hybrid storage. The preliminary evaluation in some benchmarks shows that qSDS can gain better performance compared with other strategies.\",\n \"Title: OptRS: An Optimized Algorithm Based on CRS Codes in Big Data Storage Systems.\\nYear: 2015\\n\\nAbstract: It is well-known that erasure codes, such as Reed-Solomon (RS) and Cauchy RS (CRS) codes, have played an important roles in big data storage systems to both industry and academia. While RS and CRS codes provide significant saving in storage space, they can impose a huge burden of systems performance while encoding and decoding. By studying existing high reliability and space saving rate of coding technologies, it is urgent to deploy an efficient erasure coding mechanism into distributed storage systems, which is the main storage architecture in big data era.This paper puts forward an optimized algorithm named OptRS (Optimized RS), which can not only guarantee the system’s reliability, but also enhance the efficiency and utilization of storage space. The dominant type of encoding and decoding inside erasure codes is matrix computation. In order to accelerate the speed of calculation, OptRS transferred the computation of matrix Galois field mapping into the XOR operation. Additionally, OptRS has developed the elimination schemes to minimize the numbers of XOR. Through theory analysis, we can conclude that OptRS algorithm improved the performance of encoding and decoding lead to shorten the computation time the same as verified by the test. The encoding efficiency with OptRS coding achieves 36.1 % and 58.2 % acceleration than using CRS and RS coding, respectively. The decoding rate by using OptRS can increase 19.3 % and 33.1 % compared with CRS and RS averagely by quantitative studying.\",\n \"Title: User Identity Linkage by Latent User Space Modelling\\nYear: 2016\\n\\nAbstract: User identity linkage across social platforms is an important problem of great research challenge and practical value. In real applications, the task often assumes an extra degree of difficulty by requiring linkage across multiple platforms. While pair-wise user linkage between two platforms, which has been the focus of most existing solutions, provides reasonably convincing linkage, the result depends by nature on the order of platform pairs in execution with no theoretical guarantee on its stability. In this paper, we explore a new concept of ``Latent User Space'' to more naturally model the relationship between the underlying real users and their observed projections onto the varied social platforms, such that the more similar the real users, the closer their profiles in the latent user space. We propose two effective algorithms, a batch model(ULink) and an online model(ULink-On), based on latent user space modelling. Two simple yet effective optimization methods are used for optimizing objective function: the first one based on the constrained concave-convex procedure(CCCP) and the second on accelerated proximal gradient. To our best knowledge, this is the first work to propose a unified framework to address the following two important aspects of the multi-platform user identity linkage problem --- (I) the platform multiplicity and (II) online data generation. We present experimental evaluations on real-world data sets for not only traditional pairwise-platform linkage but also multi-platform linkage. The results demonstrate the superiority of our proposed method over the state-of-the-art ones.\",\n \"Title: Prioritized Grid Highway Long Short-Term Memory-Based Universal Background Model for Speaker Verification.\\nYear: 2017\\n\\nAbstract: Prioritized grid long short-term memory (pGLSTM) has been shown to improve automatic speech recognition efficiently. In this paper, we implement this state-of-the-art model of ASR tasks for text-independent Chinese language speaker verification tasks in which DNN/i-Vector (DNN-based i-Vector) framework is adopted along with PLDA backend. To fully explore the performance, we compared the presented pGLSTM based UBM to GMM-UBM and HLSTM-UBM. Due to constraint of the amount of Chinese transcribed corpus for ASR training, we also explore an adaptation method by firstly training the pGLSTM-UBM on English language with large amount of corpus and use a PLDA adaptation backend to fit into Chinese language before the final speaker verification scoring. Experiments show that both pGLSTM-UBM model with corresponding PLDA backend and pGLSTM-UBM with adapted PLDA backend achieve better performance than the traditional GMM-UBM model. Additionally the pGLSTM-UBM with PLDA backend achieves performance of 4.94% EER in 5 s short utterance and 1.97% EER in 10 s short utterance, achieving 47% and 51% drop comparing to that of GMM. Experiment results imply that DNN from ASR tasks can expand the advantage of UBM model especially in short utterance and that better DNN model for ASR tasks could achieve extra gain in speaker verification tasks.\",\n \"Title: Assistance of Speech Recognition in Noisy Environment with Sentence Level Lip-Reading.\\nYear: 2017\\n\\nAbstract: Acoustic speech recognition, as a technique to decode text from a speech, receives a great success in recent years. The trained model of Ping An Technology (ShenZhen) Co., Ltd results in a word error rate (WER) of 8.4%, which shows competitive performance among popular business products. However, an assumption of the achievement is the quiet environment of the speech. In a noisy environment, the accuracy will decrease 10%–20%. For the improvement in such environment, a multi-modal biometric system integrating acoustic speech-recognition with sentence level lip-reading is designed. In several noisy situations, the 5.7% averaged word error rate (WER) of the results of our integrated system indicates a significant improvement to the pure acoustic speech-recognition system.\",\n \"Title: Video-Based Pig Recognition with Feature-Integrated Transfer Learning.\\nYear: 2018\\n\\nAbstract: Automatic detection and recognition of animals has long been a popular topic. It can be used on different areas, such as ecosystem protection, farming industry, insurance industry, etc. Currently, there is still no robust and efficient method for this problem. Deep neural network, a recently rapid developing technology, has shown its great power on image processing, but suffers from low training speed problem. Recently, transfer learning has become popular because it avoids training the network from scratch, which significantly speeds up the training speed. In this paper, we focus on the pig recognition contest organized by a Chinese finance company. Applying all frames for training the neural networks with VGG-19 will result in an accuracy lower than 60% in the prediction steps. With experiments, we find out a key to enhance the accuracy of the video-based pig recognition task is that the frames have to be carefully selected with a certain algorithm. To take advantage of the strengths of different network architectures, we apply feature integration method with the deep neural networks of DPN131, InceptionV3 and Xception network together. We then implement the integrated feature to train the labelled dataset which are frames extracted from the videos of 30 pigs. The resulted model receive an prediction accuracy of 96.41%. Experiments show that the best performance of our proposed methods outperforms all classic deep neural networks training from scratch.\",\n \"Title: Social Network Monitoring for Bursty Cascade Detection.\\nYear: 2018\\n\\nAbstract: Social network services have become important and efficient platforms for users to share all kinds of information. The capability to monitor user-generated information and detect bursts from information diffusions in these social networks brings value to a wide range of real-life applications, such as viral marketing. However, in reality, as a third party, there is always a cost for gathering information from each user or so-called social network sensor. The question then arises how to select a budgeted set of social network sensors to form the data stream for burst detection without compromising the detection performance. In this article, we present a general sensor selection solution for different burst detection approaches. We formulate this problem as a constraint satisfaction problem that has high computational complexity. To reduce the computational cost, we first reduce most of the constraints by making use of the fact that bursty cascades are rare among the whole population. We then transform the problem into an Linear Programming (LP) problem. Furthermore, we use the sub-gradient method instead of the standard simplex method or interior-point method to solve the LP problem, which makes it possible for our solution to scale up to large social networks. Evaluating our solution on millions of real information cascades, we demonstrate both the effectiveness and efficiency of our approach.\",\n \"Title: A Noise-Robust Self-Adaptive Multitarget Speaker Detection System\\nYear: 2018\\n\\nAbstract: We describe a multitarget speaker detection system that provides a robust way to classify the utterance of a speaker in noisy environments. The multitarget detection problem is known to be much more difficult to tackle than single target speaker verification tasks, especially when the target set is large and the data is corrupted by noise. In this work we aim to improve the performance of our multitarget speaker detection system in real-world settings, where complicated background noise and unpredictable speaker behavior are present. We make three major improvements that contribute to our goal. First, we discover an effective noise-filtering method using GMM-based voice activity detector followed by unsupervised bottom-up clustering. Second, we incorporate a Highway-LSTM network to estimate posterior distributions of senones, replacing the traditional GMM-UBM with senone posteriors. Finally, we apply a self-adaptive approach on the classifier back-end so that our PLDA parameters and S-normalization subsets can be updated online.\",\n \"Title: Who Should Be Invited to My Party: A Size-Constrained k-Core Problem in Social Networks.\\nYear: 2019\\n\\nAbstract: In this paper, we investigate the problem of a size-constrained k-core group query (SCCGQ) in social networks, taking both user closeness and network topology into consideration. More specifically, SCCGQ intends to find a group of h users that has the highest social closeness while being a k-core. SCCGQ can be widely applied to event planning, task assignment, social analysis, and many other fields. In contrast to existing work on the k-core detection problem, which aims to find a k-core in a social network, SCCGQ not only focuses on k-core detection but also takes size constraints into consideration. Although the conventional k-core detection problem can be solved in linear time, SCCGQ has a higher complexity. To solve the problem of SCCGQ, we propose a Blast Scatter (BS) algorithm, which appoints the query node as the center to begin outward expansions via breadth search. In each outward expansion, BS finds a new center through a greedy strategy and then selects multiple neighbors of the center. To speed up the BS algorithm, we propose an advanced search algorithm, called Bounded Extension (BE). Specifically, BE combines an effective social distance pruning strategy and a tight upper bound of social closeness to prune the search space considerably. In addition, we propose an offline social-aware index to accelerate the query processing. Finally, our experimental results demonstrate the efficiency and effectiveness of our proposed algorithms on large real-world social networks.\",\n \"Title: Composer4Everyone: Automatic Music Generation with Audio Motif\\nYear: 2019\\n\\nAbstract: We introduct Composer4Everyone, a wechat-based application that automatically generates music for a piece of audio recording. A user with little composition experience would also be able to create his own work by a simple interaction of humming, singing or even speaking. The input audio is taken as a motif and developed into a piece of piano music of 20-30 seconds. A rearranging system is provided for users to change the piano music into a different style.\",\n \"Title: Dropout Regularization for Self-Supervised Learning of Transformer Encoder Speech Representation.\\nYear: 2021\\n\\nAbstract: Predicting the altered acoustic frames is an effective way of self-supervised learning for speech representation. However, it is challenging to prevent the pretrained model from overfitting. In this paper, we proposed to introduce two dropout regularization methods into the pretraining of transformer encoder: (1) attention dropout, (2) layer dropout. Both of the two dropout methods encourage the model to utilize global speech information, and avoid just copying local spectrum features when reconstructing the masked frames. We evaluated the proposed methods on phoneme classification and speaker recognition tasks. The experiments demonstrate that our dropout approaches achieve competitive results, and improve the performance of classification accuracy on downstream tasks.\",\n \"Title: Loss Prediction: End-to-End Active Learning Approach For Speech Recognition\\nYear: 2021\\n\\nAbstract: End-to-end speech recognition systems usually require huge amounts of labeling resource, while annotating the speech data is complicated and expensive. Active learning is the solution by selecting the most valuable samples for annotation. In this paper, we proposed to use a predicted loss that estimates the uncertainty of the sample. The CTC (Connectionist Temporal Classification) and attention loss are informative for speech recognition since they are computed based on all decoding paths and alignments. We defined an end-to-end active learning pipeline, training an ASR/LP (Automatic Speech Recognition/Loss Prediction) joint model. The proposed approach was validated on an English and a Chinese speech recognition task. The experiments show that our approach achieves competitive results, outperforming random selection, least confidence, and estimated loss method.\",\n \"Title: Variational Information Bottleneck for Effective Low-Resource Audio Classification.\\nYear: 2021\\n\\nAbstract: Large-scale deep neural networks (DNNs) such as convolutional neural networks (CNNs) have achieved impressive performance in audio classification for their powerful capacity and strong generalization ability. However, when training a DNN model on low-resource tasks, it is usually prone to overfitting the small data and learning too much redundant information. To address this issue, we propose to use variational information bottleneck (VIB) to mitigate overfitting and suppress irrelevant information. In this work, we conduct experiments ona 4-layer CNN. However, the VIB framework is ready-to-use and could be easily utilized with many other state-of-the-art network architectures. Evaluation on a few audio datasets shows that our approach significantly outperforms baseline methods, yielding more than 5.0% improvement in terms of classification accuracy in some low-source settings.\",\n \"Title: Speech2Video - Cross-Modal Distillation for Speech to Video Generation.\\nYear: 2021\\n\\nAbstract: This paper investigates a novel task of talking face video generation solely from speeches. The speech-to-video generation technique can spark interesting applications in entertainment, customer service, and human-computer-interaction industries. Indeed, the timbre, accent and speed in speeches could contain rich information relevant to speakers' appearance. The challenge mainly lies in disentangling the distinct visual attributes from audio signals. In this article, we propose a light-weight, cross-modal distillation method to extract disentangled emotional and identity information from unlabelled video inputs. The extracted features are then integrated by a generative adversarial network into talking face video clips. With carefully crafted discriminators, the proposed framework achieves realistic generation results. Experiments with observed individuals demonstrated that the proposed framework captures the emotional expressions solely from speeches, and produces spontaneous facial motion in the video output. Compared to the baseline method where speeches are combined with a static image of the speaker, the results of the proposed framework is almost indistinguishable. User studies also show that the proposed method outperforms the existing algorithms in terms of emotion expression in the generated videos.\",\n \"Title: Federated Learning with Dynamic Transformer for Text to Speech.\\nYear: 2021\\n\\nAbstract: Text to speech (TTS) is a crucial task for user interaction, but TTS model training relies on a sizable set of high-quality original datasets. Due to privacy and security issues, the original datasets are usually unavailable directly. Recently, federated learning proposes a popular distributed machine learning paradigm with an enhanced privacy protection mechanism. It offers a practical and secure framework for data owners to collaborate with others, thus obtaining a better global model trained on the larger dataset. However, due to the high complexity of transformer models, the convergence process becomes slow and unstable in the federated learning setting. Besides, the transformer model trained in federated learning is costly communication and limited computational speed on clients, impeding its popularity. To deal with these challenges, we propose the federated dynamic transformer. On the one hand, the performance is greatly improved comparing with the federated transformer, approaching centralize-trained Transformer-TTS when increasing clients number. On the other hand, it achieves faster and more stable convergence in the training phase and significantly reduces communication time. Experiments on the LJSpeech dataset also strongly prove our method's advantage.\",\n \"Title: Quantum Convolutional Neural Network on Protein Distance Prediction\\nYear: 2021\\n\\nAbstract: Proteins are linear polymers that fold into an incredible variety of three-dimensional structures that enable sophisticated functionality for biology. Predicting protein distance with high precision remains challenging, particularly for small protein families. As deep learning achieves remarkable success in many areas, deep learning also allows scientists to predict proteins' three-dimensional structure. As convolutional neural networks have a powerful ability to learn data features at multiple levels of abstraction, we deploy CNN to predict protein distance. To accelerate the training process, we apply a quantum convolutional neural network(QCNN) to improve the protein structure prediction efficiently. For QCNN, the conventional convolutional layer is transformed to a quantum convolution or quanvolutional layer. Since the protein data has large input, we explore the large dimension of these quantum transformations. And in experiments, we compare the different number of layers in QCNN during the training phase. We found the QCNN is similar to CNN that is the deeper layer can get better performance. The simulations show the proposed method can accelerate the convergence while maintaining the performance.\",\n \"Title: When Hearing the Voice, Who Will Come to Your Mind\\nYear: 2021\\n\\nAbstract: Speech is a carrier containing rich biological information, such as speaker identity information including age, gender, race. In this paper, we explore the use of a self-supervised method to obtain speaker identity information from high-dimensional speech representations to generate face image. At the same time, considering that the biological information contained in the same piece of speech has different expression forms (such as images), we designed a cross-modal knowledge distillation method to transform the feature information from the visual domain to the speech domain. The feature vectors obtained through self-supervised learning and knowledge distillation are fed into a GAN-based generative model to obtain facial images containing speaker information. Subjective experiments show that our model can reach a well performance in the task of speaker identification. Experiments show that our proposed method can effectively establish the connection between different modalities and generate a face with rich biological information.\",\n \"Title: Automatic Joint Optimization of Algorithm-Level Compression and Compiler-Based Acceleration with Reinforcement Learning for DNN in Edge Devices\\nYear: 2021\\n\\nAbstract: More accurate machine learning models often require more memory cost and more software-hardware co-adaption efforts for deployments on resource-constrained devices. Model compression techniques and deep learning compiler are developed to reduce the memory cost and latency. However, current methods require tremendous engineering efforts to optimize the model manually. This paper introduces a jointly learning based framework to perform the compression task and the acceleration task simultaneously. The joint optimization method auto-tunes the algorithm-level compression and compiler-based acceleration with reinforcement learning. The experiment results demonstrate that we compress the model by a factor of 2 or 8, and accelerate the optimization up to 30 times using our learning framework.\",\n \"Title: Enhancing Neural Architecture Search by Upgrading Weak Components\\nYear: 2021\\n\\nAbstract: Neural Architecture Search (NAS) becomes increasingly popular due to the ability to liberate the researchers from the complicated model design. However, typical NAS methods search for high-quality networks at a substantial cost of time and resources. This work enhances the neural architecture search by upgrading the weak components of promising candidate networks. First, we define a search space stacked with repeated components, such as cells and blocks. Second, we propose an attention-wise component evaluation metric to score the components. Third, we exploit a novel search policy to discover weak and strong components in promising candidate networks. Lastly, we use strong components to replace weak components. Besides, to achieve higher accuracy with less time cost, we integrate two optimization schemes: knowledge transfer and self-ensemble. The knowledge transfer accelerates model training by integrating an attentive regularizer into the objective goal. And the self-ensemble method ensembles promising candidate networks as the teacher network to teach the student network. The experiment results demonstrate our method can achieve state-of-the-art results(97.48% accuracy on CIFAR-10 and 84.38% accuracy on CIFAR-100).\",\n \"Title: Contrastive Learning for improving End-to-end Speaker Verification\\nYear: 2021\\n\\nAbstract: Speaker verification involves examining the speech signal to authenticate the claim of a speaker as true or false. Deep neural networks are one of the successful implementations of complex non-linear models to learn unique and invariant features of data. They have been employed in speech recognition tasks and have shown their potential to be used for speaker recognition also. However, the overfitting problem is remained to prevent the model's performance. In this study, we apply contrastive learning on speaker verification tasks to solve the robustness problem. Besides, we introduce domain adaptive loss on the tasks. Experimental results and ablation study that indicate that our proposed model outperforms various baseline end-to-end methods significantly by at least relative 10%, including d-vector approaches, deep-speaker, and generalized end-to-end model, for text-dependent speaker verification on a company's internal text-dependent voice command DataSet.\",\n \"Title: Diversified Point Cloud Classification Using Personalized Federated Learning\\nYear: 2021\\n\\nAbstract: As a comprehensive and unstructured data source describing 3 dimensional (3D) objects, point cloud data has attracted wide interest from researchers. Neural networks (NNs) provide flexible, end-to-end solutions to point cloud processing tasks. Yet, one of the unavoidable problems in training the NNs is the difficulty in collecting and labeling high-quality point cloud data. Existing point cloud datasets are often collected at different scales and densities. Directly combining highly heterogeneous datasets might violate data protection regulations, but also lead to degradation of model performance. In our experiments, naive horizontal federated learning has been applied to alleviate the data privacy concern. However, when the datasets are not identically distributed, the federated model's performance falls far behind the state-of-the-art of centralized models. This paper investigates the union of highly heterogeneous point cloud datasets for the object classification task. In the proposed framework, the federated model is split into shared and personalized modules. The former improves generalizability by bringing multiple data sources into play, while the latter adapts local distribution and avoids convergence at false optima. Experiments show that the proposed framework FedPCN achieves 35.1% higher accuracy than FedAvg. At local test samples, FedPCN also outperforms the locally trained model by 0.5%.\",\n \"Title: Transfer Ability of Monolingual Wav2vec2.0 for Low-resource Speech Recognition\\nYear: 2021\\n\\nAbstract: Recently, there are several domains that have their own feature extractors, such as ResNet, BERT, and GPT-x, which are widely used for various down-stream tasks. These models are pre-trained on large amounts of unlabeled data by self-supervision. In the speech domain, wav2vec2.0 starts to show its powerful representation ability and feasibility for ultra-low resource speech recognition tasks. This speech feature extractor is pre-trained on the monolingual audiobook corpus, whereas it has not been thoroughly examined in real spoken scenarios and other languages. In this work, we endeavor to transfer the knowledge from the pre-trained monolingual wav2vec2.0 to cross-lingual spoken ASR tasks with less than 20 hours of labeled data. We achieve more than 20% relative improvements in all the six languages compared with previous methods, establishing a strong benchmark on CALLHOME datasets. Compared with supervised pre-training, self-supervision training used in wav2vec2.0 has a better transfer ability. We also find that using coarse-grained modeling units, such as subword or character, usually achieves better results than fine-grained modeling units, such as phone or letter.\",\n \"Title: A Language Model Based Pseudo-Sample Deliberation for Semi-supervised Speech Recognition\\nYear: 2021\\n\\nAbstract: End-to-end modeling requires tremendous amounts of transcribed speech to achieve an automatic speech recognition (ASR) model with high performance. For low-resource ASR tasks, it is a promising approach to utilize the highly accessible unlabeled speech and text corpus. Previous works have shown that training with pseudo samples, which are the inferring results given the unlabeled speech, can substantially improve the accuracy of a baseline ASR model. Besides the common data filtering to improve pseudo-label quality, we propose an alternative pseudo-sample deliberation method that operates on the output of the ASR model through a pre-trained bidirectional language model (BERT). It fixes the unreasonable tokens in the inference by substitution, which can distill knowledge from the large text corpus. Experiments on Librispeech show that assisted with our fixing operation, self-training on additional unlabeled samples can bridge up to 82.3% of the gap with the supervised training.\",\n \"Title: Semantic Extraction for Sentence Representation via Reinforcement Learning\\nYear: 2021\\n\\nAbstract: Many modern Natural Language Processing(NLP) systems rely on word embeddings, previously trained in an unsupervised manner on large corpora, as base features. Several attempts of learning unsupervised sentence representations have not achieved satisfactory performance and have not been widely adopted. In this work, we present a Semantic Extraction Reinforcement learning Model(SERM) for encoding sentences into embedding vectors, which transforms the learning process into intent detection and named entity recognition tasks. Intent detection is mainly related to the semantics of the whole sentence, while named entity recognition pays more attention to local entities. Given a sentence, SERM builds a sentence representation by extracting the most important words and removing irrelevant words in a sentence. Unlike the mainstream approach, SERM compresses sentences from semantic and entity perspectives and this allows us to efficiently learn different types of encoding functions. The experimental results show that SERM can learn high quality sentence representation. This paper demonstrates that our sentence representations have sufficient competitiveness with the best performing model on text classification task.\",\n \"Title: CACnet: Cube Attentional CNN for Automatic Speech Recognition\\nYear: 2021\\n\\nAbstract: End-to-end models have been widely used in Automatic Speech Recognition (ASR). Convolutional Neural Networks (CNNs) can effectively use spectrum information to model acoustic models. However, the convolution layers have limitations on the receptive field leading to restrictions for long speech signals. Inspired by this, we propose a Cube Attention CNN network(CACnet) that uses two different attention blocks to integrate the feature information of different dimensions for extending context information. Thereinto, the Global Deep Attention Block utilizes non-local operations to compute interactions between any two positions on feature maps and enables the acquirement of global feature representations while the Cross-Channel Attention Block adaptively recalibrates channel-wise feature responses. Then, outputs of the above two attention modules will be added up to further improve the feature representation which contributes to enrich contextual information. Finally, the performance of our proposed architecture will be explored under ASR tasks in English circumstances. Experiments on LibriSpeech indicate that CACnet achieves a word error rate (WER) of 3.78%/9.56% without language model (LM), and 2.84%/6.97% with LM, which is near state-of-the-art accuracy. CACnet on WSJ with 4.4% WER obtains better performance, compared to CTC-based CNN models, such as QuartzNet and Jasper, with the same language model. The proposed network achieves competitive accuracy while having fewer parameters. Moreover, CACnet can be easily incorporated into any existed network since it has the same input and output dimensions.\",\n \"Title: Avqvc: One-Shot Voice Conversion By Vector Quantization With Applying Contrastive Learning.\\nYear: 2022\\n\\nAbstract: Voice Conversion(VC) refers to changing the timbre of a speech while retaining the discourse content. Recently, many works have focused on disentangle-based learning techniques to separate the timbre and the linguistic content information from a speech signal. Once successful, voice conversion will be feasible and straightforward. This paper proposed a novel one-shot voice conversion framework based on vector quantization voice conversion (VQVC) and AutoVC, called AVQVC. A new training method is applied to VQVC to separate content and timbre information from speech more effectively. The result shows that this approach has better performance than VQVC in separating content and timbre to improve the sound quality of generated speech.\",\n \"Title: nnSpeech: Speaker-Guided Conditional Variational Autoencoder for Zero-Shot Multi-speaker text-to-speech.\\nYear: 2022\\n\\nAbstract: Multi-speaker text-to-speech (TTS) using a few adaption data is a challenge in practical applications. To address that, we propose a zero-shot multi-speaker TTS, named nnSpeech, that could synthesis a new speaker voice without fine-tuning and using only one adaption utterance. Compared with using a speaker representation module to extract the characteristics of new speakers, our method bases on a speaker-guided conditional variational autoencoder and can generate a variable Z, which contains both speaker characteristics and content information. The latent variable Z distribution is approximated by another variable conditioned on reference mel-spectrogram and phoneme. Experiments on the English corpus, Mandarin corpus, and cross-dataset proves that our model could generate natural and similar speech with only one adaption speech.\",\n \"Title: VU-BERT: A Unified Framework for Visual Dialog.\\nYear: 2022\\n\\nAbstract: The visual dialog task attempts to train an agent to answer multi-turn questions given an image, which requires the deep understanding of interactions between the image and dialog history. Existing researches tend to employ the modality-specific modules to model the interactions, which might be troublesome to use. To fill in this gap, we propose a unified framework for image-text joint embedding, named VU-BERT, and apply patch projection to obtain vision embedding firstly in visual dialog tasks to simplify the model. The model is trained over two tasks: masked language modeling and next utterance retrieval. These tasks help in learning visual concepts, utterances dependence, and the relationships between these two modalities. Finally, our VU-BERT achieves competitive performance (0.7287 NDCG scores) on VisDial v1.0 Datasets.\",\n \"Title: DRVC: A Framework of Any-to-Any Voice Conversion with Self-Supervised Learning.\\nYear: 2022\\n\\nAbstract: Any-to-any voice conversion problem aims to convert voices for source and target speakers, which are out of the training data. Previous works wildly utilize the disentangle-based models. The disentangle-based model assumes the speech consists of content and speaker style information and aims to untangle them to change the style information for conversion. Previous works focus on reducing the dimension of speech to get the content information. But the size is hard to determine to lead to the untangle overlapping problem. We propose the Disentangled Representation Voice Conversion (DRVC) model to address the issue. DRVC model is an end-to-end self-supervised model consisting of the content encoder, timbre encoder, and generator. Instead of the previous work for reducing speech size to get content, we propose a cycle for restricting the disentanglement by the Cycle Reconstruct Loss and Same Loss. The experiments show there is an improvement for converted speech on quality and voice similarity.\",\n \"Title: RECONSTRUCTING DUAL LEARNING FOR NEURAL VOICE CONVERSION USING RELATIVELY FEW SAMPLES\\nYear: 2021\\n\\nAbstract: This paper introduces a dual learning system for neural voice conversion (DualVC) using relatively few samples based on the symmetry of the speech conversion task. The system contains a pair of sequence-to-sequence neural networks that have the same structure but are trained in opposite directions. The objective function of the dual model training is the sum of paired conversion loss and reconstruction loss during the dual training circle. The models in the two directions are trained alternately to guide each other by the corresponding reconstruction loss. Furthermore, curriculum learning techniques are used to load models in existing fields into the current task to accelerate the rapid iteration and convergence of the model. The experiment on the voice conversion task with the proposed DualVC and curriculum learning strategy obtained a comparable naturalness and similarity with only a 30% dataset than the BaseVC model trained on the full dataset.\",\n \"Title: TGAVC: IMPROVING AUTOENCODER VOICE CONVERSION WITH TEXT-GUIDED AND ADVERSARIAL TRAINING\\nYear: 2021\\n\\nAbstract: Non-parallel many-to-many voice conversion remains an interesting but challenging speech processing task. Recently, AutoVC, a conditional autoencoder based method, achieved excellent conversion results by disentangling the speaker identity and the speech content using information-constraining bottlenecks. However, due to the pure autoencoder training method, it is difficult to evaluate the separation effect of content and speaker identity. In this paper, a novel voice conversion framework, named Text Guided AutoVC(TGAVC), is proposed to more effectively separate content and timbre from speech, where an expected content embedding produced based on the text transcriptions is designed to guide the extraction of voice content. In addition, the adversarial training is applied to eliminate the speaker identity information in the estimated content embedding extracted from speech. Under the guidance of the expected content embedding and the adversarial training, the content encoder is trained to extract speaker-independent content embedding from speech. Experiments on AIShell-3 dataset show that the proposed model outperforms AutoVC in terms of naturalness and similarity of converted speech.\",\n \"Title: CYCLEGEAN: CYCLE GENERATIVE ENHANCED ADVERSARIAL NETWORK FOR VOICE CONVERSION\\nYear: 2021\\n\\nAbstract: Cycle Generative Adversarial Network (CycleGAN) for voice conversion (VC) task only used discriminators to identify whether the input voice is generated or real. It means the confrontational does not check the similarity with the target voice, leading the generated voice not much similar to the target. In this paper, instead of vocal checking, we propose to enhance the confrontation to target similarity checking that addresses this problem. A Cycle Generative Enhanced Adversarial Network (CycleGEAN) was introduced to make the original two discriminators to target classifier and non-target classifier. The target classifier aims to identify whether the target speaks the input voice or not. Similarly, the non-target classifier identifies the non-target voice. Furthermore, we add a gradient reversal layer with different operations for target and non-target. Then in each GAN, we used both classifiers. One is the discriminator, and the other is trained for using in another GAN. In experiments, the proposed method compare to CycleGAN improves Mean Opinion Score (MOS) of 0.1 and Voice Similarity Score (VSS) of 0.2 on the Voice Conversion Challenge 2018 (VCC2018) dataset.\",\n \"Title: r-G2P: Evaluating and Enhancing Robustness of Grapheme to Phoneme Conversion by Controlled Noise Introducing and Contextual Information Incorporation.\\nYear: 2022\\n\\nAbstract: Grapheme-to-phoneme (G2P) conversion is the process of converting the written form of words to their pronunciations. It has an important role for text-to-speech (TTS) synthesis and automatic speech recognition (ASR) systems. In this paper, we aim to evaluate and enhance the robustness of G2P models. We show that neural G2P models are extremely sensitive to orthographical variations in graphemes like spelling mistakes. To solve this problem, we propose three controlled noise introducing methods to synthesize noisy training data. Moreover, we incorporate the contextual information with the baseline and propose a robust training strategy to stabilize the training process. The experimental results demonstrate that our proposed robust G2P model (r-G2P) outperforms the baseline significantly (-2.73\\\\% WER on Dict-based benchmarks and -9.09\\\\% WER on Real-world sources).\",\n \"Title: Towards Speaker Age Estimation With Label Distribution Learning.\\nYear: 2022\\n\\nAbstract: Existing methods for speaker age estimation usually treat it as a multi-class classification or a regression problem. However, precise age identification remains a challenge due to label ambiguity, \\\\emph{i.e.}, utterances from adjacent age of the same person are often indistinguishable. To address this, we utilize the ambiguous information among the age labels, convert each age label into a discrete label distribution and leverage the label distribution learning (LDL) method to fit the data. For each audio data sample, our method produces a age distribution of its speaker, and on top of the distribution we also perform two other tasks: age prediction and age uncertainty minimization. Therefore, our method naturally combines the age classification and regression approaches, which enhances the robustness of our method. We conduct experiments on the public NIST SRE08-10 dataset and a real-world dataset, which exhibit that our method outperforms baseline methods by a relatively large margin, yielding a 10\\\\% reduction in terms of mean absolute error (MAE) on a real-world dataset.\",\n \"Title: Self-Attention for Incomplete Utterance Rewriting.\\nYear: 2022\\n\\nAbstract: Incomplete utterance rewriting (IUR) has recently become an essential task in NLP, aiming to complement the incomplete utterance with sufficient context information for comprehension. In this paper, we propose a novel method by directly extracting the coreference and omission relationship from the self-attention weight matrix of the transformer instead of word embeddings and edit the original text accordingly to generate the complete utterance. Benefiting from the rich information in the self-attention weight matrix, our method achieved competitive results on public IUR datasets.\",\n \"Title: Adaptive Few-Shot Learning Algorithm for Rare Sound Event Detection.\\nYear: 2022\\n\\nAbstract: Sound event detection is to infer the event by understanding the surrounding environmental sounds. Due to the scarcity of rare sound events, it becomes challenging for the well-trained detectors which have learned too much prior knowledge. Meanwhile, few-shot learning methods promise a good generalization ability when facing a new limited-data task. Recent approaches have achieved promising results in this field. However, these approaches treat each support example independently, ignoring the information of other examples from the whole task. Because of this, most of previous methods are constrained to generate a same feature embedding for all test-time tasks, which is not adaptive to each inputted data. In this work, we propose a novel task-adaptive module which is easy to plant into any metric-based few-shot learning frameworks. The module could identify the task-relevant feature dimension. Incorporating our module improves the performance considerably on two datasets over baseline methods, especially for the transductive propagation network. Such as +6.8% for 5-way 1-shot accuracy on ESC-50, and +5.9% on noiseESC-50. We investigate our approach in the domain-mismatch setting and also achieve better results than previous methods.\",\n \"Title: MetaSID: Singer Identification with Domain Adaptation for Metaverse.\\nYear: 2022\\n\\nAbstract: Metaverse has stretched the real world into unlimited space. There will be more live concerts in Metaverse. The task of singer identification is to identify the song belongs to which singer. However, there has been a tough problem in singer identification, which is the different live effects. The studio version is different from the live version, the data distribution of the training set and the test set are different, and the performance of the classifier decreases. This paper proposes the use of the domain adaptation method to solve the live effect in singer identification. Three methods of domain adaptation combined with Convolutional Recurrent Neural Network (CRNN) are designed, which are Maximum Mean Discrepancy (MMD), gradient reversal (Revgrad), and Contrastive Adaptation Network (CAN). MMD is a distance-based method, which adds domain loss. Revgrad is based on the idea that learned features can represent different domain samples. CAN is based on class adaptation, it takes into account the correspondence between the categories of the source domain and target domain. Experimental results on the public dataset of Artist20 show that CRNN-MMD leads to an improvement over the baseline CRNN by 0.14. The CRNN-RevGrad outperforms the baseline by 0.21. The CRNN-CAN achieved state of the art with the F1 measure value of 0.83 on album split.\",\n \"Title: Singer Identification for Metaverse with Timbral and Middle-Level Perceptual Features.\\nYear: 2022\\n\\nAbstract: Metaverse is an interactive world that combines reality and virtuality, where participants can be virtual avatars. Anyone can hold a concert in a virtual concert hall, and users can quickly identify the real singer behind the virtual idol through the singer identification. Most singer identification methods are processed using the frame-level features. However, expect the singer's timbre, the music frame includes music information, such as melodiousness, rhythm, and tonal. It means the music information is noise for using frame-level features to identify the singers. In this paper, instead of only the frame-level features, we propose to use another two features that address this problem. Middle-level feature, which represents the music's melodiousness, rhythmic stability, and tonal stability, and is able to capture the perceptual features of music. The timbre feature, which is used in speaker identification, represents the singers' voice features. Furthermore, we propose a convolutional recurrent neural network (CRNN) to combine three features for singer identification. The model firstly fuses the frame-level feature and timbre feature and then combines middle-level features to the mix features. In experiments, the proposed method achieves comparable performance on an average F1 score of 0.81 on the benchmark dataset of Artist20, which significantly improves related works.\",\n \"Title: TDASS: Target Domain Adaptation Speech Synthesis Framework for Multi-speaker Low-Resource TTS.\\nYear: 2022\\n\\nAbstract: Recently, synthesizing personalized speech by text-to-speech (TTS) application is highly demanded. But the previous TTS models require a mass of target speaker speeches for training. It is a high-cost task, and hard to record lots of utterances from the target speaker. Data augmentation of the speeches is a solution but leads to the low-quality synthesis speech problem. Some multi-speaker TTS models are proposed to address the issue. But the quantity of utterances of each speaker imbalance leads to the voice similarity problem. We propose the Target Domain Adaptation Speech Synthesis Network (TDASS) to address these issues. Based on the backbone of the Tacotron2 model, which is the high-quality TTS model, TDASS introduces a self-interested classifier for reducing the non-target influence. Besides, a special gradient reversal layer with different operations for target and non-target is added to the classifier. We evaluate the model on a Chinese speech corpus, the experiments show the proposed method outperforms the baseline method in terms of voice quality and voice similarity.\",\n \"Title: SUSing: SU-net for Singing Voice Synthesis.\\nYear: 2022\\n\\nAbstract: Singing voice synthesis is a generative task that involves multi-dimensional control of the singing model, including lyrics, pitch, and duration, and includes the timbre of the singer and singing skills such as vibrato. In this paper, we proposed SU-net for singing voice synthesis named SUSing. Synthesizing singing voice is treated as a translation task between lyrics and music score and spectrum. The lyrics and music score information is encoded into a two-dimensional feature representation through the convolution layer. The two-dimensional feature and its frequency spectrum are mapped to the target spectrum in an autoregressive manner through a SU-net network. Within the SU-net the stripe pooling method is used to replace the alternate global pooling method to learn the vertical frequency relationship in the spectrum and the changes of frequency in the time domain. The experimental results on the public dataset Kiritan show that the proposed method can synthesize more natural singing voices.\",\n \"Title: Improving Human Image Synthesis with Residual Fast Fourier Transformation and Wasserstein Distance\\nYear: 2022\\n\\nAbstract: With the rapid development of the Metaverse, virtual humans have emerged, and human image synthesis and editing techniques, such as pose transfer, have recently become popular. Most of the existing techniques rely on GANs, which can generate good human images even with large variants and occlusions. But from our best knowledge, the existing state-of-the-art method still has the following problems: the first is that the rendering effect of the synthetic image is not realistic, such as poor rendering of some regions. And the second is that the training of GAN is unstable and slow to converge, such as model collapse. Based on the above two problems, we propose several methods to solve them. To improve the rendering effect, we use the Residual Fast Fourier Transform Block to replace the traditional Residual Block. Then, spectral normalization and Wasserstein distance are used to improve the speed and stability of GAN training. Experiments demonstrate that the methods we offer are effective at solving the problems listed above, and we get state-of-the-art scores in LPIPS and PSNR.\",\n \"Title: Augmentation-induced Consistency Regularization for Classification\\nYear: 2022\\n\\nAbstract: Deep neural networks have become popular in many supervised learning tasks, but they may suffer from overfitting when the training dataset is limited. To mitigate this, many researchers use data augmentation, which is a widely used and effective method for increasing the variety of datasets. However, the randomness introduced by data augmentation causes inevitable inconsistency between training and inference, which leads to poor improvement. In this paper, we propose a consistency regularization framework based on data augmentation, called CR-Aug, which forces the output distributions of different sub models generated by data augmentation to be consistent with each other. Specifically, CR-Aug evaluates the discrepancy between the output distributions of two augmented versions of each sample, and it utilizes a stop-gradient operation to minimize the consistency loss. We implement CR-Aug to image and audio classification tasks and conduct extensive experiments to verify its effectiveness in improving the generalization ability of classifiers. Our CR-Aug framework is ready-to-use, it can be easily adapted to many state-of-the-art network architectures. Our empirical results show that CR-Aug outperforms baseline methods by a significant margin.\",\n \"Title: A Novel Capsule Aggregation Framework for Natural Language Inference\\nYear: 2021\\n\\nAbstract: Recent advances have advocated the use of complex attention mechanism to capture interactive information between premise and hypothesis in Natural Language Inference (NLI). However, few studies have focused on the further processing of matching feature, i.e. information aggregation. In this paper, we first investigate a novel capsule network for NLI, referred as Gcap. Gcap utilizes a gated enhanced fusion operation to obtain richer features between massive soft alignment information. Then the capsule aggregates those features through routing algorithms. Benefit from the routing mechanism of the capsule network, Gcap can dynamically generate feature vectors for subsequent classifier. Evaluation results demonstrate that our model achieves accuracy of 89.1%, 88.2% and 79.6% (79.3%) on SNLI, SciTail and MultiNLI datasets respectively, which outperforms the strong baseline with gains of 0.2%, 1.4% and 0.3% (0.6%). In particular, we compare the runtime inference efficiency of BERT and our model. Our model can attain up to 33.3x speedup in online inference time. Thanks to dynamic aggregation, Gcap shows a strong ability to distinguish those cases that are easily confused.\",\n \"Title: Self-supervised Learning for Semantic Sentence Matching with Dense Transformer Inference Network\\nYear: 2021\\n\\nAbstract: Semantic sentence matching concerns predicting the relationship between a pair of natural language sentences. Recently, many methods based on interaction structure have been proposed, usually involving encoder, matching, and aggregation parts. Although some of them obtain impressive results, the simple encoder training from scratch cannot extract the global features of sentences effectively, and the transmission of information in the stacked network will cause certain loss. In this paper, we propose a Densely-connected Inference-Attention network (DCIA) to maximize the use of the feature from each layer of the network by dense connection mechanism and to get robust encoder by self-supervised learning (SSL) based on contrastive method, which can maximize the mutual information between global features and local features of input data. We have conducted experiments on Quora, MRPC, and SICK dataset, the experimental results show that our method owns competitive results on these dataset where we drive 89.13%, 78.1% and 87.7% accuracies respectively. In addition, the accuracy of DCIA with SSL will surpass the one of DCIA without SSL by about 2%.\",\n \"Title: Cali3F: Calibrated Fast Fair Federated Recommendation System.\\nYear: 2022\\n\\nAbstract: The increasingly stringent regulations on privacy protection have sparked interest in federated learning. As a distributed machine learning framework, it bridges isolated data islands by training a global model over devices while keeping data localized. Specific to recommendation systems, many federated recommendation algorithms have been proposed to realize the privacy-preserving collaborative recommendation. However, several constraints remain largely unexplored. One big concern is how to ensure fairness between participants of federated learning, that is, to maintain the uniformity of recommendation performance across devices. On the other hand, due to data heterogeneity and limited networks, additional challenges occur in the convergence speed. To address these problems, in this paper, we first propose a personalized federated recommendation system training algorithm to improve the recommendation performance fairness. Then we adopt a clustering-based aggregation method to accelerate the training process. Combining the two components, we proposed Cali3F, a calibrated fast and fair federated recommendation framework. Cali3F not only addresses the convergence problem by a within-cluster parameter sharing approach but also significantly boosts fairness by calibrating local models with the global model. We demonstrate the performance of Cali3F across standard benchmark datasets and explore the efficacy in comparison to traditional aggregation approaches.\",\n \"Title: QSpeech: Low-Qubit Quantum Speech Application Toolkit\\nYear: 2022\\n\\nAbstract: Quantum devices with low qubits are common in the Noisy Intermediate-Scale Quantum (NISQ) era. However, Quantum Neural Network (QNN) running on low-qubit quantum devices would be difficult since it is based on Variational Quantum Circuit (VQC), which requires many qubits. Therefore, it is critical to make QNN with VQC run on low-qubit quantum devices. In this study, we propose a novel VQC called the low-qubit VQC. VQC requires numerous qubits based on the input dimension; however, the low-qubit VQC with linear transformation can liberate this condition. Thus, it allows the QNN to run on low-qubit quantum devices for speech applications. Furthermore, as compared to the VQC, our proposed low-qubit VQC can stabilize the training process more. Based on the low-qubit VQC, we implement QSpeech, a library for quick prototyping of hybrid quantum-classical neural networks in the speech field. It has numerous quantum neural layers and QNN models for speech applications. Experiments on Speech Command Recognition and Text-to-Speech show that our proposed low-qubit VQC outperforms VQC and is more stable.\",\n \"Title: DT-SV: A Transformer-based Time-domain Approach for Speaker Verification.\\nYear: 2022\\n\\nAbstract: Speaker verification (SV) aims to determine whether the speaker's identity of a test utterance is the same as the reference speech. In the past few years, extracting speaker embeddings using deep neural networks for SV systems has gone mainstream. Recently, different attention mechanisms and Transformer networks have been explored widely in SV fields. However, utilizing the original Transformer in SV directly may have frame-level information waste on output features, which could lead to restrictions on capacity and discrimination of speaker embeddings. Therefore, we propose an approach to derive utterance-level speaker embeddings via a Transformer architecture that uses a novel loss function named diffluence loss to integrate the feature information of different Transformer layers. Therein, the diffluence loss aims to aggregate frame-level features into an utterance-level representation, and it could be integrated into the Transformer expediently. Besides, we also introduce a learnable mel-fbank energy feature extractor named time-domain feature extractor that computes the mel-fbank features more precisely and efficiently than the standard mel-fbank extractor. Combining Diffluence loss and Time-domain feature extractor, we propose a novel Transformer-based time-domain SV model (DT-SV) with faster training speed and higher accuracy. Experiments indicate that our proposed model can achieve better performance in comparison with other models.\",\n \"Title: Federated Split BERT for Heterogeneous Text Classification\\nYear: 2022\\n\\nAbstract: Pre-trained BERT models have achieved impressive performance in many natural language processing (NLP) tasks. However, in many real-world situations, textual data are usually decentralized over many clients and unable to be uploaded to a central server due to privacy protection and regulations. Federated learning (FL) enables multiple clients collaboratively to train a global model while keeping the local data privacy. A few researches have investigated BERT in federated learning setting, but the problem of performance loss caused by heterogeneous (e.g., non-IID) data over clients remain under-explored. To address this issue, we propose a framework, FedSplitBERT, which handles heterogeneous data and decreases the communication cost by splitting the BERT encoder layers into local part and global part. The local part parameters are trained by the local client only while the global part parameters are trained by aggregating gradients of multiple clients. Due to the sheer size of BERT, we explore a quantization method to further reduce the communication cost with minimal performance loss. Our framework is ready-to-use and compatible to many existing federated learning algorithms, including FedAvg, FedProx and FedAdam. Our experiments verify the effectiveness of the proposed framework, which outperforms baseline methods by a significant margin, while FedSplitBERT with quantization can reduce the communication cost by $11.9\\\\times$.\",\n \"Title: Federated Non-negative Matrix Factorization for Short Texts Topic Modeling with Mutual Information\\nYear: 2022\\n\\nAbstract: Non-negative matrix factorization (NMF) based topic modeling is widely used in natural language processing (NLP) to uncover hidden topics of short text documents. Usually, training a high-quality topic model requires large amount of textual data. In many real-world scenarios, customer textual data should be private and sensitive, precluding uploading to data centers. This paper proposes a Federated NMF (FedNMF) framework, which allows multiple clients to collaboratively train a high-quality NMF based topic model with locally stored data. However, standard federated learning will significantly undermine the performance of topic models in downstream tasks (e.g., text classification) when the data distribution over clients is heterogeneous. To alleviate this issue, we further propose FedNMF+MI, which simultaneously maximizes the mutual information (MI) between the count features of local texts and their topic weight vectors to mitigate the performance degradation. Experimental results show that our FedNMF+MI methods outperform Federated Latent Dirichlet Allocation (FedLDA) and the FedNMF without MI methods for short texts by a significant margin on both coherence score and classification F1 score.\",\n \"Title: Leveraging Causal Inference for Explainable Automatic Program Repair\\nYear: 2022\\n\\nAbstract: Deep learning models have made significant progress in automatic program repair. However, the black-box nature of these methods has restricted their practical applications. To address this challenge, this paper presents an interpretable approach for program repair based on sequence-to-sequence models with causal inference and our method is called CPR, short for causal program repair. Our CPR can generate explanations in the process of decision making, which consists of groups of causally related input-output tokens. Firstly, our method infers these relations by querying the model with inputs disturbed by data augmentation. Secondly, it generates a graph over tokens from the responses and solves a partitioning problem to select the most relevant components. The experiments on four programming languages (Java, C, Python, and JavaScript) show that CPR can generate causal graphs for reasonable interpretations and boost the performance of bug fixing in automatic program repair.\",\n \"Title: A Fair Federated Learning Framework With Reinforcement Learning\\nYear: 2022\\n\\nAbstract: Federated learning (FL) is a paradigm where many clients collaboratively train a model under the coordination of a central server, while keeping the training data locally stored. However, heterogeneous data distributions over different clients remain a challenge to mainstream FL algorithms, which may cause slow convergence, overall performance degradation and unfairness of performance across clients. To address these problems, in this study we propose a reinforcement learning framework, called PG-FFL, which automatically learns a policy to assign aggregation weights to clients. Additionally, we propose to utilize Gini coefficient as the measure of fairness for FL. More importantly, we apply the Gini coefficient and validation accuracy of clients in each communication round to construct a reward function for the reinforcement learning. Our PG-FFL is also compatible to many existing FL algorithms. We conduct extensive experiments over diverse datasets to verify the effectiveness of our framework. The experimental results show that our framework can outperform baseline methods in terms of overall performance, fairness and convergence speed.\",\n \"Title: Adaptive Activation Network for Low Resource Multilingual Speech Recognition\\nYear: 2022\\n\\nAbstract: Low resource automatic speech recognition (ASR) is a useful but thorny task, since deep learning ASR models usually need huge amounts of training data. The existing models mostly established a bottleneck (BN) layer by pre-training on a large source language, and transferring to the low resource target language. In this work, we introduced an adaptive activation network to the upper layers of ASR model, and applied different activation functions to different languages. We also proposed two approaches to train the model: (1) cross-lingual learning, replacing the activation function from source language to target language, (2) multilingual learning, jointly training the Connectionist Temporal Classification (CTC) loss of each language and the relevance of different languages. Our experiments on IARPA Babel datasets demonstrated that our approaches outperform the from-scratch training and traditional bottleneck feature based methods. In addition, combining the cross-lingual learning and multilingual learning together could further improve the performance of multilingual speech recognition.\",\n \"Title: Speech Augmentation Based Unsupervised Learning for Keyword Spotting\\nYear: 2022\\n\\nAbstract: In this paper, we investigated a speech augmentation based unsupervised learning approach for keyword spotting (KWS) task. KWS is a useful speech application, yet also heavily depends on the labeled data. We designed a CNN-Attention architecture to conduct the KWS task. CNN layers focus on the local acoustic features, and attention layers model the long-time dependency. To improve the robustness of KWS model, we also proposed an unsupervised learning method. The unsupervised loss is based on the similarity between the original and augmented speech features, as well as the audio reconstructing information. Two speech augmentation methods are explored in the unsupervised learning: speed and intensity. The experiments on Google Speech Commands V2 Dataset demonstrated that our CNN-Attention model has competitive results. Moreover, the augmentation based unsupervised learning could further improve the classification accuracy of KWS task. In our experiments, with augmentation based unsupervised learning, our KWS model achieves better performance than other unsupervised methods, such as CPC, APC, and MPC.\",\n \"Title: Micro-Expression Recognition Based on Attribute Information Embedding and Cross-modal Contrastive Learning\\nYear: 2022\\n\\nAbstract: Facial micro-expressions recognition has attracted much attention recently. Micro-expressions have the characteristics of short duration and low intensity, and it is difficult to train a high-performance classifier with the limited number of existing micro-expressions. Therefore, recognizing micro-expressions is a challenge task. In this paper, we propose a micro-expression recognition method based on attribute information embedding and cross-modal contrastive learning. We use 3D CNN to extract RGB features and FLOW features of micro-expression sequences and fuse them, and use BERT network to extract text information in Facial Action Coding System. Through cross-modal contrastive loss, we embed attribute information in the visual network, thereby improving the representation ability of micro-expression recognition in the case of limited samples. We conduct extensive experiments in CASME II and MMEW databases, and the accuracy is 77.82% and 71.04%, respectively. The comparative experiments show that this method has better recognition effect than other methods for micro-expression recognition.\",\n \"Title: A Privacy-Preserving Subgraph-Level Federated Graph Neural Network via Differential Privacy.\\nYear: 2022\\n\\nAbstract: Currently, the federated graph neural network (GNN) has attracted a lot of attention due to its wide applications in reality without violating the privacy regulations. Among all the privacy-preserving technologies, the differential privacy (DP) is the most promising one due to its effectiveness and light computational overhead. However, the DP-based federated GNN has not been well investigated, especially in the sub-graph-level setting, such as the scenario of recommendation system. The biggest challenge is how to guarantee the privacy and solve the non independent and identically distributed (non-IID) data in federated GNN simultaneously. In this paper, we propose DP-FedRec, a DP-based federated GNN to fill the gap. Private Set Intersection (PSI) is leveraged to extend the local graph for each client, and thus solve the non-IID problem. Most importantly, DP is applied not only on the weights but also on the edges of the intersection graph from PSI to fully protect the privacy of clients. The evaluation demonstrates DP-FedRec achieves better performance with the graph extension and DP only introduces little computations overhead.\",\n \"Title: Uncertainty Calibration for Deep Audio Classifiers.\\nYear: 2022\\n\\nAbstract: Although deep Neural Networks (DNNs) have achieved tremendous success in audio classification tasks, their uncertainty calibration are still under-explored. A well-calibrated model should be accurate when it is certain about its prediction and indicate high uncertainty when it is likely to be inaccurate. In this work, we investigate the uncertainty calibration for deep audio classifiers. In particular, we empirically study the performance of popular calibration methods: (i) Monte Carlo Dropout, (ii) ensemble, (iii) focal loss, and (iv) spectral-normalized Gaussian process (SNGP), on audio classification datasets. To this end, we evaluate (i-iv) for the tasks of environment sound and music genre classification. Results indicate that uncalibrated deep audio classifiers may be over-confident, and SNGP performs the best and is very efficient on the two datasets of this paper.\",\n \"Title: SpeechEQ: Speech Emotion Recognition based on Multi-scale Unified Datasets and Multitask Learning\\nYear: 2022\\n\\nAbstract: Speech emotion recognition (SER) has many challenges, but one of the main challenges is that each framework does not have a unified standard. In this paper, we propose SpeechEQ, a framework for unifying SER tasks based on a multi-scale unified metric. This metric can be trained by Multitask Learning (MTL), which includes two emotion recognition tasks of Emotion States Category (EIS) and Emotion Intensity Scale (EIS), and two auxiliary tasks of phoneme recognition and gender recognition. For this framework, we build a Mandarin SER dataset - SpeechEQ Dataset (SEQD). We conducted experiments on the public CASIA and ESD datasets in Mandarin, which exhibit that our method outperforms baseline methods by a relatively large margin, yielding 8.0% and 6.5% improvement in accuracy respectively. Additional experiments on IEMOCAP with four emotion categories (i.e., angry, happy, sad, and neutral) also show the proposed method achieves a state-of-the-art of both weighted accuracy (WA) of 78.16% and unweighted accuracy (UA) of 77.47%.\",\n \"Title: Tiny-Sepformer: A Tiny Time-Domain Transformer Network For Speech Separation\\nYear: 2022\\n\\nAbstract: Time-domain Transformer neural networks have proven their superiority in speech separation tasks. However, these models usually have a large number of network parameters, thus often encountering the problem of GPU memory explosion. In this paper, we proposed Tiny-Sepformer, a tiny version of Transformer network for speech separation. We present two techniques to reduce the model parameters and memory consumption: (1) Convolution-Attention (CA) block, spliting the vanilla Transformer to two paths, multi-head attention and 1D depthwise separable convolution, (2) parameter sharing, sharing the layer parameters within the CA block. In our experiments, Tiny-Sepformer could greatly reduce the model size, and achieves comparable separation performance with vanilla Sepformer on WSJ0-2/3Mix datasets.\",\n \"Title: Speech Representation Disentanglement with Adversarial Mutual Information Learning for One-shot Voice Conversion.\\nYear: 2022\\n\\nAbstract: One-shot voice conversion (VC) with only a single target speaker's speech for reference has become a hot research topic. Existing works generally disentangle timbre, while information about pitch, rhythm and content is still mixed together. To perform one-shot VC effectively with further disentangling these speech components, we employ random resampling for pitch and content encoder and use the variational contrastive log-ratio upper bound of mutual information and gradient reversal layer based adversarial mutual information learning to ensure the different parts of the latent space containing only the desired disentangled representation during training. Experiments on the VCTK dataset show the model achieves state-of-the-art performance for one-shot VC in terms of naturalness and intellgibility. In addition, we can transfer characteristics of one-shot VC on timbre, pitch and rhythm separately by speech representation disentanglement. Our code, pre-trained models and demo are available at https://im1eon.github.io/IS2022-SRDVC/.\",\n \"Title: Debias the Black-Box: A Fair Ranking Framework via Knowledge Distillation.\\nYear: 2022\\n\\nAbstract: Deep neural networks can capture the intricate interaction history information between queries and documents, because of their many complicated nonlinear units, allowing them to provide correct search recommendations. However, service providers frequently face more complex obstacles in real-world circumstances, such as deployment cost constraints and fairness requirements. Knowledge distillation, which transfers the knowledge of a well-trained complex model (teacher) to a simple model (student), has been proposed to alleviate the former concern, but the best current distillation methods focus only on how to make the student model imitate the predictions of the teacher model. To better facilitate the application of deep models, we propose a fair information retrieval framework based on knowledge distillation. This framework can improve the exposure-based fairness of models while considerably decreasing model size. Our extensive experiments on three huge datasets show that our proposed framework can reduce the model size to a minimum of 1% of its original size while maintaining its black-box state. It also improves fairness performance by 15%~46% while keeping a high level of recommendation effectiveness.\",\n \"Title: A Nearest Neighbor Under-sampling Strategy for Vertical Federated Learning in Financial Domain\\nYear: 2022\\n\\nAbstract: BSTRACTMachine learning techniques have been widely applied in modern financial activities. Participants in the field are aware of the importance of data privacy. Vertical federated learning (VFL) was proposed as a solution to multi-party secure computation for machine learning to obtain the huge data required by the models as well as keep the privacy of the data holders. However, previous research majorly analyzed the algorithms under ideal conditions. Data imbalance in VFL is still an open problem. In this paper, we propose a privacy-preserving sampling strategy for imbalanced VFL based on federated graph embedding of the samples, without leaking any distribution information. The participants of the federation provide partial neighbor information for each sample during the intersection stage and the controversial negative sample will be filtered out. Experiments were conducted on commonly used financial datasets and one real-world dataset. Our proposed approach obtained the leading F1 score on all tested datasets on comparing with the baseline under sampling strategies for VFL.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":73,"string":"73"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":282,"string":"282"}}},{"rowIdx":283,"cells":{"question_id":{"kind":"string","value":"Wei Guan"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Dft Study On Proton Transfers In Hydrolysis Reactions Of Phosphate Dianion And Sulfate Monoanion\" using the following items: B3LYP calculations, hydrolysis reactions, phosphate, sulfate, reactivity"},"answer":{"kind":"string","value":"B3LYP calculations were carried out on hydrolysis reactions of monosubstituted(R) phosphate dianion and sulfate monoanion. In the reacting system, water clusters (H2O)(22) and (H2O)(35) are included to trace reaction paths. For both P and S substrates with R=methyl group, elementary processes were calculated. While the phosphate undergoes the substitution at the phosphorus, the sulfate does at the methyl carbon. For the S substrate with R=neopentyl group, the product tert-amyl alcohol was found to be formed via a dyotropic rearrangement from the neopentyl alcohol intermediate. For R=aryl groups, transition-state geometries were calculated to be similar between P and S substrates. Calculated activation energies are in good agreement with experimental values. After the rate-determining transition state of the substitution, the hydronium ion H3O+ is formed at the third water molecule. It was suggested that alkyl and aryl substrates are of the different reactivity of the hydrolysis. (c) 2014 Wiley Periodicals, Inc."},"correct_answer":{"kind":"string","value":"B3LYP calculations were carried out on hydrolysis reactions of monosubstituted(R) phosphate dianion and sulfate monoanion. In the reacting system, water clusters (H2O)(22) and (H2O)(35) are included to trace reaction paths. For both P and S substrates with R=methyl group, elementary processes were calculated. While the phosphate undergoes the substitution at the phosphorus, the sulfate does at the methyl carbon. For the S substrate with R=neopentyl group, the product tert-amyl alcohol was found to be formed via a dyotropic rearrangement from the neopentyl alcohol intermediate. For R=aryl groups, transition-state geometries were calculated to be similar between P and S substrates. Calculated activation energies are in good agreement with experimental values. After the rate-determining transition state of the substitution, the hydronium ion H3O+ is formed at the third water molecule. It was suggested that alkyl and aryl substrates are of the different reactivity of the hydrolysis. (c) 2014 Wiley Periodicals, Inc."},"documents":{"kind":"list like","value":["Title: Intelligent Transportation Systems\nYear: 2006\n\nAbstract: This Works in Progress department discusses 10 ongoing intelligent transportation systems projects. TIME, Sentient Transport, Electric-Vehicle Terminal, DynaChina, and TrafficView focus on traffic and vehicular data collection, transmission, and analysis. Other projects aim to provide intelligent-copilot services for drivers; focus on asset identification and data collection for railroad environments; are building application development environments for automobiles; and are designing a multimodal biometric identification system for travel documents. This department is part of a special issue on Intelligent Transportation.","Title: Including and optimizing shape parameters in Doo-Sabin subdivision surfaces for interpolation\nYear: 2007\n\nAbstract: This paper considers the problems of how to introduce shape parameters into recursive subdivision schemes for additional shape control and how to find appropriate values of shape parameters to improve the quality of subdivision surface shapes. Following Brunet, we restrict our discussion to the algorithm that constructs a Doo-Sabin subdivision surface to interpolate the vertices of an input polyhedron with arbitrary topology. While Brunet defined one so-called \"shape handle\" for each vertex of the initial polyhedron, which is used to scale the type-V face obtained after the first step of the subdivision process, we introduce three shape parameters for each vertex: one for the scale and the other two for the orientation of the type-V face. This gives more degrees of freedom to optimize the shape of the result interpolatory surface. We develop a genetic algorithm to compute the optimal set of shape parameters such that a \"fairness\" measure of the surface is minimized. Examples are provided to demonstrate the effects of the optimal shape parameters on the final interpolatory surfaces.","Title: View-Based 3D Model Transmission via Mesh Segmentation\nYear: 2007\n\nAbstract: For network-based graphics applications, a key challenge is how to efficiently transmit complex three-dimensional (3D) models over bandwidth-limited communication channels such as wireless links. Most existing 3D mesh coding algorithms do not consider the view-dependent rendering issue, and therefore result in transmitting unnecessary portions of 3D mesh models which leads to the waste in precious network bandwidth. In this paper, we propose a novel view-dependent 3D model transmission scheme, where a 3D model is partitioned into a number of segments, each segment is then independently coded using the MPEG-4 3DMC coding algorithm, and finally only the visible segments are selected and delivered to the client. Such a view-based 3D model transmission is able to substantially save the transmission bandwidth and therefore has a significant impact on wireless network based graphics applications.","Title: Design and Implementation of Bus Monitoring System Based on GPS for Beijing Olympics\nYear: 2009\n\nAbstract: To guarantee the safety of public transport and effectiveness in dispatching buses, overall solution on Beijing Bus Monitoring System (BJ-BMS) based on GPS is put forward in this paper. The system is composed of communication control and GIS subsystems, each of which was independently developed in the beginning and integrated in the end.The key technologies of the system are described in detail. In addition to some fundamental functions such as real-time monitoring, some featured functions tightly combined with the daily operations in Beijing Bus Company are realized in the BJ-BMS. Finally, the status of system implementation and maintenance are introduced, which have proven to be very effective in practical applications during 2008 Beijing Olympics.","Title: Robust pose estimation in untextured environments for augmented reality applications\nYear: 2009\n\nAbstract: We present a robust camera pose estimation approach for stereo images captured in untextured environments. Unlike most of existing registration algorithms which are point-based and make use of intensities of pixels in the neighborhood, our approach imports line segments in registration process. With line segments as primitives, the proposed algorithm is capable to handle untextured images such as scenes captured in man-made environments, as well as the cases when there are large viewpoint changes or illumination changes. Furthermore, since the proposed algorithm is robust to large base-line stereos, there are improvements on the accuracy of 3D points reconstruction. With well-calculated camera pose and object positions in 3D space, we can embed virtual objects into existing scene with higher accuracy for realistic effects. In our experiments, 2D labels are embedded in the 3D scene space to achieve annotation effects as in AR.","Title: Diversity Analysis of Non-Coherent Wireless Network Coding.\nYear: 2013\n\nAbstract: Network coding has been widely used in the wireless uplink. To do coherent detection at the receiver, channel estimation is performed to collect the channel state information (CSI). For multi-user channels, the channel estimation overhead is sometimes formidable and may even outweigh the network coding gain. To address this issue, we study the non-coherent network coding in this work. Both the ana...","Title: Estimation of camera pose with respect to terrestrial LiDAR data\nYear: 2013\n\nAbstract: In this paper, we present an algorithm that is to estimate the position of a hand-held camera with respect to terrestrial LiDAR data. Our input is a set of 3D range scans with intensities and one or a set of 2D uncalibrated camera images of the scene. The algorithm that automatically registers range scans and 2D images is composed of following steps. In the first step, we project the terrestrial LiDAR onto 2D images according to several preselected viewpoints. Intensity-based features such as SIFT are extracted from these projected images and these features are projected back onto the LiDAR data to obtain their 3D positions. In the second step, we estimate the initial pose of given 2D images from feature correspondences. In the third step, we refine the coarse camera pose obtained from the previous step through iterative matchings and optimization process. We presents results from experiments in several different urban settings.","Title: Outlier Detection of Handover Data for Inner-Suburban Freeway Traffic Information Estimation Using Mobile Probes\nYear: 2011\n\nAbstract: Mobile probes provide a supplementary means of traffic information estimation for inner-suburban freeways in the major big cities in China. Lack of sufficient participants with GPS-based smart phones at the moment, handover-based location solution, one of GSM-based location solutions, was tentatively employed in this paper. Since handover data currently cannot have the same location performance with GPS data, low location accuracy has been a great challenge for traffic information estimation. To improve the estimated accuracy of travelling speed using mobile probes, an outlier detection algorithm of handover data is developed for identifying those handover links with large estimated errors. The developed outlier detection algorithm contains two steps, outlier detection of individual handover link and outlier detection of linked handover links. LS-SVM ensemble classifier is employed in the first step and a statistical-based algorithm is employed in the second step. Evaluations of the developed algorithm were finally studied using field data collected in a preliminary field test in a stretch of inner suburban freeway in Beijing, China.","Title: Developing a Toolset Supporting the Construction of Reusable Components for Embedded Control Systems\nYear: 2010\n\nAbstract: Reusing software components for embedded control applications enhances product quality and reduces time to market when appropriate (formal) methodologies and supporting toolsets are available. That is why industrial companies are interested in developing trusted, in-house reusable components for specific areas of application. This creates a demand for tools supporting the construction of reusable components, with various artifacts produced automatically out of component models and deposited into a repository. Thus, pre-fabricated and ready to use components can be reused to fabricate applications. That demand can be satisfied by a highly customized toolset providing an integrated development environment for rapid graphical component specification, component validation, automatic generation of artifacts and documentation. The paper presents a possible solution for creating a customized toolset based on open-source technology, in accordance with industrial requirements, as well as the approach used to engineer a toolset supporting component development for embedded control applications.","Title: Adaptive fault-tolerant output-feedback control of LTI systems subject to actuator saturation\nYear: 2009\n\nAbstract: This paper is concerned with the problem of designing adaptive fault-tolerant output-feedback controllers for linear time-invariant (LTI) systems with actuator saturation. By combining the linear matrix inequality (LMI) approach for output-feedback controllers design and adaptive method, a method of designing adaptive reliable output-feedback controllers is proposed, where the controller parameter matrices are updated automatically to compensate the controller failures effects on systems based on the online estimations of eventual faults. The designs are developed in the framework of LMI approach, which can enlarge the domain of asymptotic stability of closed-loop systems in the cases of actuator saturation and actuator failures. An example is given to illustrate the efficiency of the design method.","Title: Segmentation-Based View-Dependent 3-D Graphics Model Transmission\nYear: 2008\n\nAbstract: For wireless network based graphics applications, a key challenge is how to efficiently transmit complex 3-D models over bandwidth-limited wireless channels. Most existing 3-D mesh transmission systems do not consider such a view-dependent delivery issue, and thus transmit unnecessary portions of 3-D mesh models, which leads to the waste in precious wireless network bandwidth. In this paper, we propose a novel view-dependent 3-D model transmission scheme, where a 3-D model is partitioned into a number of segments, each segment is then independently coded using the MPEG-4 3DMC coding algorithm, and finally only the visible segments are selected and delivered to the client. Moreover, we also propose analytical models to find the optimal number of segments so as to minimize the average transmission size. Simulation results show that such a view-based 3-D model transmission is able to substantially save the transmission bandwidth and therefore has a significant impact on wireless graphics applications.","Title: Sn1-Sn2 And Sn2-Sn3 Mechanistic Changes Revealed By Transition States Of The Hydrolyses Of Benzyl Chlorides And Benzenesulfonyl Chlorides\nYear: 2014\n\nAbstract: Hydrolysis reactions of benzyl chlorides and benzenesulfonyl chlorides were theoretically investigated with the density functional theory method, where the water molecules are explicitly considered. For the hydrolysis of benzyl chlorides (para-ZC(6)H(4)CH(2)Cl), the number of water molecules (n) slightly influences the transition-state (TS) structure. However, the para-substituent (Z) of the phenyl group significantly changes the reaction process from the stepwise (S(N)1) to the concerted (S(N)2) pathway when it changes from the typical electron-donating group (EDG) to the typical electron-withdrawing one (EWG). The EDG stabilizes the carbocation (MeOC6H4CH2+), which in turn makes the S(N)1 mechanism more favorable and vice versa. For the hydrolysis of benzenesulfonyl chlorides (para-ZC(6)H(4)SO(2)Cl), both the Z group and n influence the TS structure. For the combination of the large n value (n>9) and EDG, the S(N)2 mechanism was preferred. Conversely, for the combination of the small n value and EWG, the S(N)3 one was more favorable. (c) 2014 Wiley Periodicals, Inc.","Title: Implications of collection/delivery points for transport and logistics.\nYear: 2011\n\nAbstract: Failed first-time home deliveries may result in carrier's repeated delivery journeys and also consumer's trips to retrieve their failed deliveries from the carrier's depot. Home shopping is rapidly becoming a significant generator of logistics activity, and efforts are being devoted to identify the transport and environmental implications of those failed home deliveries. The attended collection/delivery point (CDP) concept is one solution to deal with the first-time delivery failures, using a variety of locations (for example, convenience stores, post offices) as alternative addresses to receive deliveries. Using two databases of households from across Winchester and West Sussex (UK), this article confirms that certain benefits might accrue from using networks of Local Collect post offices, supermarkets and railway stations as CDPs, compared with the traditional delivery method where the carrier may make several redelivery attempts to the home, with the customer making a personal trip to the carrier's depot in the event that these attempts also fail.","Title: Efficient matchings and mobile augmented reality\nYear: 2012\n\nAbstract: With the fast-growing popularity of smart phones in recent years, augmented reality (AR) on mobile devices is gaining more attention and becomes more demanding than ever before. However, the limited processors in mobile devices are not quite promising for AR applications that require real-time processing speed. The challenge exists due to the fact that, while fast features are usually not robust enough in matchings, robust features like SIFT or SURF are not computationally efficient. There is always a tradeoff between robustness and efficiency and it seems that we have to sacrifice one for the other. While this is true for most existing features, researchers have been working on designing new features with both robustness and efficiency. In this article, we are not trying to present a completely new feature. Instead, we propose an efficient matching method for robust features. An adaptive scoring scheme and a more distinctive descriptor are also proposed for performance improvements. Besides, we have developed an outdoor augmented reality system that is based on our proposed methods. The system demonstrates that not only it can achieve robust matchings efficiently, it is also capable to handle large occlusions such as passengers and moving vehicles, which is another challenge for many AR applications.","Title: Efficient matchings in augmented reality application\nYear: 2012\n\nAbstract: With fast growing popularity of smart phones in recent years, augmented reality (AR) becomes more demanding than ever before. However, one of main challenges is that while features like SIFT or SURF are robust in matchings, they are not computationally efficient. In this paper, we propose an efficient matching method for robust features. A distinctive descriptor is also proposed for performance improvements. Besides, we have developed an outdoor augmented reality system that is based on our proposed methods. The system demonstrates that not only it can achieve robust matchings efficiently, it is also capable to handle large occlusions such as passengers and moving vehicles.","Title: Capacity Based Fast Receive Antenna Subset Selection In Mimo System\nYear: 2008\n\nAbstract: In this letter, we develop a two-step receive antenna selection method to maximize channel capacity. Different from previous work, we first derive a lower bound on capacity based on Hadamard inequality and arithmetic-geometric mean inequality, which is then used to iteratively drop the worst-performing antennas according to their measure. The recursive nature of this method helps to largely reduce the computational complexity.","Title: Error performances of multiple access system using analog network coding\nYear: 2012\n\nAbstract: In this work, we study the error performances of the multiple access system using analog network coding (ANC), where all the users broadcast their data to the relays and destination simultaneously in the first phase, and the relays forward the source messages that have been mixed in the air in the second phase. Depending on the type of relay power constraint, both the variable gain relaying and fixed gain relaying are considered. We show that the error rates of both schemes scale as O(log P/P2) at high signal-to-noise ratio (SNR), where P is the transmitted power. We also show that the error performance is dominated by the relay-destination channel, thus the best relay position should be close to the destination. We also demonstrate that ANC may be outperformed by the conventional amplify-and-forward scheme when the data rate is low and the user number is not large. Finally, we propose a relay selection strategy based on Min-Max criterion that can achieve full diversity when there are multiple relays.","Title: Illumination and view dependent progressive transmission of semi-regular meshes with subdivision connectivity\nYear: 2007\n\nAbstract: For wireless network based graphics applications, a key challenge is how to efficiently transmit complex 3D models over bandwidth-limited wireless channels. Recently, several view-dependent 3D progressive mesh transmission schemes have been proposed, which save the transmission bandwidth through only delivering the visible portions of a mesh model. In this paper, we propose to incorporate the illumination effects into the existing view-depend progressive mesh transmission system to further improve the performance. In particular, we propose a novel distortion model, which consists of both illumination distortion and geometry distortion. We further simplify the distortion model in order to compute the rate-distortion function for each segment of a mesh model in a fast manner. Based on our proposed simplified distortion model, given the viewing and lighting parameters, we are able to optimally allocate bits among different segments in real time. Experimental results show that significant quality improvement can be achieved by taking into account the illumination effects.","Title: Clustering based space-time network coding\nYear: 2012\n\nAbstract: Many-to-one communication is a challenging problem in practice due to channel fading and multi-user interferences. In this work, a new protocol that leverages spatial diversity through space-time network coding is proposed. The N source nodes are first divided into K clusters, each having Q nodes, and the clusters send data successively in a time-division multiple access way. Each node behaves as a decode-and-forward relay to other clusters, and uses linear coding to combine the local symbol and the relayed symbols. To separate the multi-source signals, each node has a unique signature waveform, and linear decorrelator is used at the receivers. Both the exact Symbol Error Rate (SER) and the asymptotic SER at high signal-to-noise ratios of the M-ary phase-shift keying signal are studied then. It is shown that a diversity order of (N - Q + 1) can be achieved with a low transmission delay of K time slots, which is more bandwidth efficient than the existing protocols. Simulation results also justify the performance gains.","Title: Ovarian cancer detection from metabolomic liquid chromatography/mass spectrometry data by support vector machines.\nYear: 2009\n\nAbstract: The majority of ovarian cancer biomarker discovery efforts focus on the identification of proteins that can improve the predictive power of presently available diagnostic tests. We here show that metabolomics, the study of metabolic changes in biological systems, can also provide characteristic small molecule fingerprints related to this disease.In this work, new approaches to automatic classification of metabolomic data produced from sera of ovarian cancer patients and benign controls are investigated. The performance of support vector machines (SVM) for the classification of liquid chromatography/time-of-flight mass spectrometry (LC/TOF MS) metabolomic data focusing on recognizing combinations or \"panels\" of potential metabolic diagnostic biomarkers was evaluated. Utilizing LC/TOF MS, sera from 37 ovarian cancer patients and 35 benign controls were studied. Optimum panels of spectral features observed in positive or/and negative ion mode electrospray (ESI) MS with the ability to distinguish between control and ovarian cancer samples were selected using state-of-the-art feature selection methods such as recursive feature elimination and L1-norm SVM.Three evaluation processes (leave-one-out-cross-validation, 12-fold-cross-validation, 52-20-split-validation) were used to examine the SVM models based on the selected panels in terms of their ability for differentiating control vs. disease serum samples. The statistical significance for these feature selection results were comprehensively investigated. Classification of the serum sample test set was over 90% accurate indicating promise that the above approach may lead to the development of an accurate and reliable metabolomic-based approach for detecting ovarian cancer.","Title: Augmented distinctive features for efficient image matching\nYear: 2011\n\nAbstract: Finding corresponding image points is a challenging computer vision problem, especially for confusing scenes with surfaces of low textures or repeated patterns. Despite the well-known challenges of extracting conceptually meaningful high-level matching primitives, many recent works describe high-level image features such as edge groups, lines and regions, which are more distinctive than traditional local appearance based features, to tackle such difficult scenes. In this paper, we propose a different and more general approach, which treats the image matching problem as a recognition problem of spatially related image patch sets. We construct augmented semi-global descriptors (ordinal codes) based on subsets of scale and orientation invariant local keypoint descriptors. Tied ranking problem of ordinal codes is handled by increasingly keypoint sampling around image patch sets. Finally, similarities of augmented features are measured using Spearman correlation coefficient. Our proposed method is compatible with a large range of existing local image descriptors. Experimental results based on standard benchmark datasets and SURF descriptors have demonstrated its distinctiveness and effectiveness.","Title: SUE Model Based on a Reliability-Admissible Reasonable Route Set\nYear: 2012\n\nAbstract: This paper proposes a reliability-admissible filtering mechanism to generate the reasonable route set for the traditional SUE model. This mechanism still takes into account traveler's cost-susceptivity, which is able to dispel the impact of dimension on the traffic assignment. The filtering formula is presented and further estimated based on the Gumbel distribution assumption for the route disutility. The corresponding Logit-based SUE model and MSA-based algorithms for the multi-class case are presented, and are verified via numerical examples. Numerical results illustrate that the hazardous routing behavior will cause heavy traffic crowding and reduce the utilization efficiency of network. In addition, a reasonable structure of travel demand will contribute to alleviate the urban traffic congestion.","Title: Performance Analysis of Two-Way Relaying with Non-Coherent Differential Modulation.\nYear: 2011\n\nAbstract: This work focuses on a two-way denoise-and-forward relaying system using non-coherent Differential Binary Phase-Shift Keying (DBPSK) modulation, which has the well-defined relay denoising function when channel state information is unknown. We first design the relay denoising function and source decoders using Maximum Likelihood (ML) principles for the general case with K parallel relays. As the ML...","Title: Image relighting and matching with illumination information\nYear: 2012\n\nAbstract: In recent years, interest point based feature such as SIFT and SURF are widely used for image matchings. While these features are robust to changes in scales, rotations, and local geometric deformations, they are usually less able to simultaneously handle viewpoint changes and large illumination changes. In this paper, we will cope with this challenging problem. The basic idea is to relight one of the two images so that the image has similar illumination conditions as the other one. After relighting process, the point based features become effective again in the matching process. Our experiments show that the proposed method has good performance for matching two images with very different illuminations.","Title: Progressive Coding and Illumination and View Dependent Transmission of 3-D Meshes Using R-D Optimization\nYear: 2010\n\nAbstract: For transmitting complex 3D models over bandwidth-limited networks, efficient mesh coding and transmission are indispensable. The state-of-the-art 3D mesh transmission system employs wavelet-based progressive mesh coder, which converts an irregular mesh into a semi-regular mesh and directly applies the zerotree-like image coders to compress the wavelet vectors, and view-dependent transmission, which saves the transmission bandwidth through only delivering the visible portions of a mesh model. We propose methods to improve both progressive mesh cod- ing and transmission based on thorough rate-distortion (R- D) analysis. In particular, by noticing that the dependency among the wavelet coefficients generated in remeshing is not being considered in the existing approaches, we propose to introduce a preprocessing step to scale up the wavelets so that the inherent dependency of wavelets can be truly understood by the zerotree-like image compression algorithms. The weights used in the scaling process are carefully designed through thoroughly analyzing the distortions of wavelets at different refinement levels. For the transmission part, we propose to incorporate the illumination effects into the existing view-depend progressive mesh transmission system to further improve the performance. We develop a novel distortion model that considers both illumi- nation distortion and geometry distortion. Based on our proposed distortion model, given the viewing and lighting parameters, we are able to optimally allocate bits among different segments in real time. Simulation results show significant improvements in both progressive compression and transmission.","Title: Building a Software Development Environment for Embedded Systems.\nYear: 2010\n\nAbstract: This paper presents the architecture of an integrated software development toolset supporting a domain-specific framework for embedded control applications. In this particular work, emphasis is put on tool requirements concerning the graphical specification, model transformation and code generation of embedded applications built of reusable executable components that are retrieved from a component repository. Furthermore, this paper attempts to cover the important aspects of the methodology and technology needed to implement a DSL development environment, with respect to both model-driven and component based development of embedded software. The technological issues discussed come largely from the experience gained during the implementation of the prototype version of the COMDES development environment. The issues investigated and problems discovered will offer hints to other research and development efforts dealing with software development environments based on models and components.","Title: Diversity Analysis of Analog Network Coding with Multi-User Interferences\nYear: 2013\n\nAbstract: Network coding can improve the bandwidth efficiency by letting multiple users share the relay channels. However, the multi-user interferences (MUI) at the intended receiver may degrade the diversity performances. So in this work, we study several diversity strategies for the multiple-access relay channel and analyze the impact of MUI on the diversity performances. Both the variable gain relaying (VGR) and the fixed gain relaying (FGR) are considered, where the relay nodes are subject to instantaneous power constraints and long-term power constraints, respectively. We first develop a Min-Max relay selection strategy and prove that full diversity can be achieved. Next, the distributed space-time block coding (DSTBC) and the diagonal distributed space-time coding (DDSTC) are studied. For DSTBC, we show that full diversity can be achieved by FGR, but the diversity of VGR is upper bounded by min (L+1, K+1), where L and K are the number of relays and users, respectively. For single-user systems, we then develop a selective DSTBC-VGR scheme to recover the diversity loss by adaptively allocating the relay power. Finally for DDSTC, we show that both FGR and VGR can achieve full diversity, and the optimum code design criterion is to maximize the minimum product distance.","Title: Robust Adaptive Synchronization Control for a Class of Perturbed and Delayed Neural Networks\nYear: 2014\n\nAbstract: This paper is concerned with the asymptotic synchronization problem of a general neural network using the robust adaptive control technique. It is considered a class of modified Cohen---Grossberg neural networks which is supposed to undergo unknown perturbations caused by state-independent nonlinearities and bounded mixed time-varying delays on neuron amplification and activation functions. An adaptive compensation control strategy is proposed to ensure the elimination of the perturbed and delayed effects by means of adaptive estimations of unknown controller parameters. Through Lyapunov stability theory, it is shown that the proposed adaptive compensation controllers can guarantee the asymptotic synchronization of neural networks without knowing the knowledge of bounds of nonlinearities and delays. A numerical example is provided to illustrate the effectiveness of the developed techniques.","Title: Bus Arrival Time Prediction Based on the k-Nearest Neighbor Method\nYear: 2012\n\nAbstract: In this paper, a modified k-nearest neighbor (k-NN) method integrating the cluster analysis and principal component analysis is applied to bus arrival time (BAT) prediction using historical bus GPS data. The methodology of the k-NN method based on processed GPS data is presented. To validate the introduced k-NN approach, empirical analysis based on data collected from the bus No. 16 of Beijing public transport holdings, Ltd. (BPT) is performed. The results show that the k-NN method has lower prediction error than the ANN model and is more powerful in the BAT prediction.","Title: Learning Protein Folding Energy Functions.\nYear: 2011\n\nAbstract: A critical open problem in ab initio protein folding is protein energy function design, which pertains to defining the energy of protein conformations in a way that makes folding most efficient and reliable. In this paper, we address this issue as a weight optimization problem and utilize a machine learning approach, learning-to-rank, to solve this problem. We investigate the ranking-via-classification approach, especially the RankingSVM method and compare it with the state-of-the-art approach to the problem using the MINUIT optimization package. To maintain the physicality of the results, we impose non-negativity constraints on the weights. For this we develop two efficient non-negative support vector machine (NNSVM) methods, derived from L2-norm SVM and L1-norm SVMs, respectively. We demonstrate an energy function which maintains the correct ordering with respect to structure dissimilarity to the native state more often, is more efficient and reliable for learning on large protein sets, and is qualitatively superior to the current state-of-the-art energy function.","Title: Re-Examination Of Applying Wavelet Based Progressive Image Coder For 3d Semi-Regular Mesh Compression\nYear: 2008\n\nAbstract: The latest wavelet based 3D mesh coding schemes convert an irregular mesh into a semi-regular mesh and directly apply the zerotree-like image coders to compress the wavelet vectors generated in the remeshing process. The major problem of such type of approaches is that the particular properties of semi-regular meshes are not being considered in the zerotree-like image coders. In this paper, we propose an improved wavelet based 3D mesh coder. The basic idea is to introduce a preprocessing step to scale up the vector wavelets generated in remeshing so that the inherent dependency of wavelets can be truly understood by the zerotree-like image compression algorithms. The weights used in the scaling process are carefully designed through thoroughly analyzing the distortions of wavelets at different refinement levels. Experimental results show that our proposed mesh coder significantly outperforms the state-of-the-art wavelet based 3D mesh compression scheme.","Title: Joint MMSE Transceiver Design in Non-Regenerative MIMO Relay Systems\nYear: 2008\n\nAbstract: In this letter, we address the problem of transceiver design in a non-regenerative MIMO relay system, where linear processing is applied at both the relay and destination to jointly minimize the mean-squared error (MSE) of symbol estimations. Under average power constraint at the relay station, we show that the optimal relay-precoder always loads power across channel eigenvectors and then decomposes the equivalent MIMO channel into a set of parallel SISO channels. Simulation results demonstrate that our method outperforms other relaying schemes in terms of both BER and MSE.","Title: Sparse high-dimensional fractional-norm support vector machine via DC programming.\nYear: 2013\n\nAbstract: This paper considers a class of feature selecting support vector machines (SVMs) based on L\"q-norm regularization, where q@?(0,1). The standard SVM [Vapnik, V., 1995. The Nature of Statistical Learning Theory. Springer, NY.] minimizes the hinge loss function subject to the L\"2-norm penalty. Recently, L\"1-norm SVM (L\"1-SVM) [Bradley, P., Mangasarian, O., 1998. Feature selection via concave minimization and support vector machines. In: Machine Learning Proceedings of the Fifteenth International Conference (ICML98). Citeseer, pp. 82-90.] was suggested for feature selection and has gained great popularity since its introduction. L\"0-norm penalization would result in more powerful sparsification, but exact solution is NP-hard. This raises the question of whether fractional-norm (L\"q for q between 0 and 1) penalization can yield benefits over the existing L\"1, and approximated L\"0 approaches for SVMs. The major obstacle to answering this is that the resulting objective functions are non-convex. This paper addresses the difficult optimization problems of fractional-norm SVM by introducing a new algorithm based on the Difference of Convex functions (DC) programming techniques [Pham Dinh, T., Le Thi, H., 1998. A DC optimization algorithm for solving the trust-region subproblem. SIAM J. Optim. 8 (2), 476-505. Le Thi, H., Pham Dinh, T., 2008. A continuous approach for the concave cost supply problem via DC programming and DCA. Discrete Appl. Math. 156 (3), 325-338.], which efficiently solves a reweighted L\"1-SVM problem at each iteration. Numerical results on seven real world biomedical datasets support the effectiveness of the proposed approach compared to other commonly-used sparse SVM methods, including L\"1-SVM, and recent approximated L\"0-SVM approaches.","Title: Recognition-driven 3D navigation in large-scale virtual environments\nYear: 2011\n\nAbstract: We present a recognition-driven navigation system for large-scale 3D virtual environments. The proposed system contains three parts, virtual environment reconstruction, feature database building and recognition-based navigation. The virtual environment is reconstructed automatically with LIDAR data and aerial images. The feature database is composed of image patches with features and registered location and orientation information. The database images are taken at different distances from the scenes with various viewing angles, and these images are then partitioned into smaller patches. When a user navigates the real world with a handheld camera, the captured image is used to estimate its location and orientation. These location and orientation information are also reflected in the virtual environment. With the proposed patch approach, the recognition is robust to large occlusions and can be done in real time. Experiments show that our proposed navigation system is efficient and well synchronized with real world navigation.","Title: Automatically extracting cancer disease characteristics from pathology reports into a Disease Knowledge Representation Model.\nYear: 2009\n\nAbstract: We introduce an extensible and modifiable knowledge representation model to represent cancer disease characteristics in a comparable and consistent fashion. We describe a system, MedTAS/P which automatically instantiates the knowledge representation model from free-text pathology reports. MedTAS/P is based on an open-source framework and its components use natural language processing principles, machine learning and rules to discover and populate elements of the model. To validate the model and measure the accuracy of MedTAS/P, we developed a gold-standard corpus of manually annotated colon cancer pathology reports. MedTAS/P achieves F1-scores of 0.97-1.0 for instantiating classes in the knowledge representation model such as histologies or anatomical sites, and F1-scores of 0.82-0.93 for primary tumors or lymph nodes, which require the extractions of relations. An F1-score of 0.65 is reported for metastatic tumors, a lower score predominantly due to a very small number of instances in the training and test sets.","Title: Anti error propagation methods for wireless uplink using network coding\nYear: 2012\n\nAbstract: Wireless network coding suffers the error propagation issues that may severely degrade the diversity performance. In this work, we develop two power scaling schemes at the relay side and two detection schemes at the receiver side, respectively, to mitigate error propagation in network-coded uplink channel and thus achieve full diversity. For the soft power scaling based link adaptive relaying, we develop a virtual channel model and demonstrate that the relay power should be such to balance the signal-to-noise ratios of the source-relay channel and relay-destination channel. As for the hard power scaling based ON-OFF relaying, we first design a decision rule based on total pairwise error probability, and then simplifies it to the threshold-based relaying strategy. At the receiver side, we show that the weighted minimum distance detection with the weight being determined by the relative link quality of source-relay channel and relay-destination channel can achieve full diversity once the global channel state information is available, otherwise the maximum likelihood detection that explicitly takes into account relay decoding error should be employed to achieve full diversity.","Title: Finite-difference modeling of the electroseismic logging in a fluid-saturated porous formation\nYear: 2008\n\nAbstract: In a fluid-saturated porous medium, an electromagnetic (EM) wavefield induces an acoustic wavefield due to the electrokinetic effect. A potential geophysical application of this effect is electroseismic (ES) logging, in which the converted acoustic wavefield is received in a fluid-filled borehole to evaluate the parameters of the porous formation around the borehole. In this paper, a finite-difference scheme is proposed to model the ES logging responses to a vertical low frequency electric dipole along the borehole axis. The EM field excited by the electric dipole is calculated separately by finite-difference first, and is considered as a distributed exciting source term in a set of extended Biot's equations for the converted acoustic wavefield in the formation. This set of equations is solved by a modified finite-difference time-domain (FDTD) algorithm that allows for the calculation of dynamic permeability so that it is not restricted to low-frequency poroelastic wave problems. The perfectly matched layer (PML) technique without splitting the fields is applied to truncate the computational region. The simulated ES logging waveforms approximately agree with those obtained by the analytical method. The FDTD algorithm applies also to acoustic logging simulation in porous formations.","Title: Map matching of mobile probes based on handover location technology\nYear: 2010\n\nAbstract: With the rapid development of wireless location technologies, mobile terminals as probes have been regarded as a feasible and low cost method for real-time and wide-area city traffic information collection. If mobile probes deployed in the suburban areas, it will be a feasible supplementary way of real-time traffic information collection in China. This paper tries to investigate map matching problem of mobile probes for further traffic information extraction in the suburban areas. In this paper, handover location technology was firstly used to collect location information for a test mobile probe in field runs on a stretch of highway in the inner suburban area in Beijing. GPS data were also collected in field tests. A map matching process is proposed to find the most matched path for the test mobile probe, including two map matching algorithms, the first one of which is used for determining the matched link for each handover in a sequence of handover and the second one of which is used for determining the matched path for the whole sequence of handover. In the first map matching algorithm, frequency of handover on a candidate link, distance between the matched position and starting node of a candidate link, and geographic topological relation were combined by D-S evidence theory to determine the matched link for each handover. In the second map matching algorithm, historical matching results, real time traveling time information, drivers' route selection behavior were combined together to find the matched path for the test mobile probe. Finally, map matching performance was verified and discussed by field data collected from test runs.","Title: Adaptive Output Feedback Control Of A Class Of Uncertain Nonlinear Systems With Unknown Time Delays\nYear: 2012\n\nAbstract: This article studies the adaptive output feedback control problem of a class of uncertain nonlinear systems with unknown time delays. The systems considered are dominated by a triangular system without zero dynamics satisfying linear growth in the unmeasurable states. The novelty of this article is that a universal-type adaptive output feedback controller is presented to time-delay systems, which can globally regulate all the states of the uncertain systems without knowing the growth rate. An illustrative example is provided to show the applicability of the developed control strategy.","Title: On analysis of wireless uplink using analog network coding with non-coherent modulations\nYear: 2012\n\nAbstract: Analog network coding (ANC) has been widely used in wireless uplink to improve throughput and provide spatial diversity. However, the receiver has to estimate the channel coefficients of all users to perform coherent detection, thus the signaling overhead is sometimes formidable and may even outweigh the performance gain. To reduce the channel estimation overhead, we study non-coherent modulations in this work with emphasis on receiver design and performance analysis. Depending on channel state information, we first develop the coherent, partial coherent and non-coherent receivers based on maximum likelihood (ML) principle. As the ML non-coherent receiver has a non-tractable integral form, we further propose two suboptimum receivers depending on the relative quality of source-relay channel and relay-destination channel.We also study the pairwise error probability, and show that full diversity is still achievable at high signal-to-noise ratios using non-coherent modulations; however, the error rate decreases much slower than that of coherent systems due to the incapability to efficiently suppress multi-user interferences. Extensive simulations are also given to verify our analytical results.","Title: Two-Way Denoise-and-Forward Relaying with Non-Coherent Differential Modulation\nYear: 2011\n\nAbstract: This work focuses on a two-way denoise-and-forward relaying system using non-coherent Differential Binary Phase-Shift Keying (DBPSK) modulation. The relay denoising function and source decoders are designed using Maximum Likelihood (ML) principles. As the ML denoising function is hard to manipulate, it is approximated as a multi-user detector followed by a physical layer network coding encoder, based on which the closed-form relay decoding error is obtained. It is further shown that the ML source decoder is actually equivalent to the typical DBPSK decoder to the relay-source channel, and the exact end-to-end Bit Error Rate (BER) is derived then. A power allocation problem is also formulated to minimize the average BER at high Signal-to-Noise Ratio (SNR). It is shown that the optimal source power is inversely proportional to the square root of the channel gain of the source-relay channel, and the optimal relay power decreases with SNR.","Title: Analysis and design of output feedback control systems in the presence of state saturation\nYear: 2009\n\nAbstract: This paper studies the problems of stability analysis and dynamic output feedback controller design for continuous-time linear systems under state saturation. In this paper, both full state saturation and partial state saturation are considered. In order to solve the key problem, a new system is constructed. Firstly, a new LMI-based method is presented for estimating the domain of attraction of the origin for a closed-loop system under state saturation. Based on this method, an LMI-based algorithm is developed for constructing dynamic output-feedback controller which guarantees that the domain of attraction of the origin for the closed-loop system is as large as possible. An example is given to illustrate the efficiency of the design method.","Title: Analysis and design of output feedback control systems in the presence of actuator saturation\nYear: 2009\n\nAbstract: In this paper, a dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant (LTI) systems with actuator saturation. Firstly, the estimation of domain of attraction is given. Then, a design method to find a larger estimation of domain of attraction is presented. In the process of design, nonconvex conditions are obtained, so a cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. Two examples are given to illustrate the efficiency of the design method.","Title: Power Allocation For Parallel Relaying System With Partial Channel State Information\nYear: 2009\n\nAbstract: We introduce a novel power allocation scheme for decode-and-forward relaying system with partial channel state (CSI) information, i.e., the source knows full CSI of source-relay link but only statistical CSI of source-destination and relay-destination links. Our objective is to minimize the outage probability by jointly allocating the transmit power between the source and relays. To avoid exhaustive search, the MAOP scheme and the MMS scheme are proposed to approach the optimal allocation in the high and low signal-to-noise ratio regimes, respectively.","Title: Analysis and controller design of discrete-time linear systems with state saturation\nYear: 2009\n\nAbstract: This paper studies the problem of stability analysis and controller design for discrete-time linear time invariant (LTI) systems with state saturation. Both full state saturation and partial state saturation are considered. Firstly, a new system model is constructed for solving the key problem. Then, a new method is presented for estimating the domain of attraction of the origin for a system with state saturation. Based on this method, an LMI-based (linear matrix inequality) iterative algorithms is proposed for determining if a given ellipsoid is contractively invariant. Moreover, an LMI-based algorithm is developed for designing dynamic output-feedback controllers which guarantee that the domain of attraction of the origin for the closed-loop system is as large as possible. An example is given to illustrate the efficiency of the design method.","Title: A Nonlinear Pairwise Swapping Dynamics to Model the Selfish Rerouting Evolutionary Game\nYear: 2013\n\nAbstract: Abstract In this paper, a nonlinear revision protocol is proposed and embedded into the traffic evolution equation of the classical proportional-switch adjustment process (PAP), developing the present nonlinear pairwise swapping dynamics (NPSD) to describe the selfish rerouting evolutionary game. It is demonstrated that i) NPSD and PAP require the same amount of network information acquisition in the route-swaps, ii) NPSD is able to prevent the over-swapping deficiency under a plausible behavior description; iii) NPSD can maintain the solution invariance, which makes the trial and error process to identify a feasible step-length in a NPSD-based swapping algorithm is unnecessary, and iv) NPSD is a rational behavior swapping process and the continuous-time NPSD is globally convergent. Using the day-to-day NPSD, a numerical example is conducted to explore the effects of the reaction sensitivity on traffic evolution and characterize the convergence of discrete-time NPSD.","Title: Mitigating Error Propagation for Wireless Network Coding\nYear: 2012\n\nAbstract: Network coding has been widely used in wireless uplink to improve spectral efficiency. However, the relay decoding error may propagate to the intended receiver and thus severely degrade the diversity performance. So in this work, we develop two power scaling schemes at the relay side and two detection schemes at the receiver side, respectively, to mitigate error propagation and thus achieve full diversity for the two-user multiple access relay network. For the soft power scaling based link adaptive relaying, we develop a virtual source-relay-destination channel model and demonstrate that the relay power should be such to balance the signal-to-noise ratios of the source-relay channel and relay-destination channel. As for the hard power scaling based ON-OFF relaying, we first design a decision rule based on total pairwise error probability, and then simplify it to the threshold-based relaying strategy. At the receiver side, we show that the weighted minimum distance detection with the weight being determined by the relative link quality of source-relay channel and relay-destination channel can achieve full diversity once the global channel state information is available, otherwise the maximum likelihood detection should be employed to achieve full diversity when the receiver only knows the local channel state information.","Title: Study on berth planning problem in a container seaport: Using an integrated programming approach\nYear: 2012\n\nAbstract: This paper provides an integrated solution for two common processes in a container seaport: namely, the Berth Allocation Process (BAP) and the Crane Scheduling Process (QCSP). These are formulated through a Bi-Level Programming (BLP) approach, which is used to characterize the highly interrelated relationships between the two processes and simultaneously, identify an integrated solution for both. The upper-level problem (BAP) is termed 'NP-hard' as its computational complexity increases exponentially with the number of incoming ships for mooring, while the lower-level problem (QCSP) is a mixed-integer linear program. A revised genetic algorithm and a branch-and-bound method (B&B) are then applied for the solutions of upper and lower level problems, respectively.","Title: GPS-aided recognition-based user tracking system with augmented reality in extreme large-scale areas\nYear: 2011\n\nAbstract: We present a recognition-based user tracking and augmented reality system that works in extreme large scale areas. The system will provide a user who captures an image of a building facade with precise location of the building and augmented information about the building. While GPS cannot provide information about camera poses, it is needed to aid reducing the searching ranges in image database. A patch-retrieval method is used for efficient computations and real-time camera pose recovery. With the patch matching as the prior information, the whole image matching can be done through propagations in an efficient way so that a more stable camera pose can be generated. Augmented information such as building names and locations are then delivered to the user. The proposed system mainly contains two parts, offline database building and online user tracking. The database is composed of images for different locations of interests. The locations are clustered into groups according to their UTM coordinates. An overlapped clustering method is used to cluster these locations in order to restrict the retrieval range and avoid ping pong effects. For each cluster, a vocabulary tree is built for searching the most similar view. On the tracking part, the rough location of the user is obtained from the GPS and the exact location and camera pose are calculated by querying patches of the captured image. The patch property makes the tracking robust to occlusions and dynamics in the scenes. Moreover, due to the overlapped clusters, the system simulates the \"soft handoff\" feature and avoid frequent swaps in memory resource. Experiments show that the proposed tracking and augmented reality system is efficient and robust in many cases.","Title: Component-based analysis of embedded control applications\nYear: 2012\n\nAbstract: The widespread use of embedded systems requires the creation of industrial software technology that will make it possible to engineer systems being correct by construction. That can be achieved through the use of validated (trusted) components, verification of design models, and automatic configuration of applications from validated design models and trusted components. This design philosophy has been instrumental for developing COMDES--a component-based framework for distributed embedded control systems. A COMDES application is conceived as a network of embedded actors that are configured from instances of reusable, executable components--function blocks (FBs). System actors operate in accordance with a timed multitasking model of computation, whereby I/O signals are exchanged with the controlled plant at precisely specified time instants, resulting in the elimination of I/O jitter. The paper presents an analysis technique that can be used to validate COMDES design models in SIMULINK. It is based on a transformation of the COMDES design model into a SIMULINK analysis model, which preserves the functional and timing behaviour of the application. This technique has been employed to develop a feasible (light-weight) analysis method based on runtime observers. The latter are conceived as special-purpose actors running in parallel with the application actors, while checking system properties specified in Linear Temporal Logic. Observers are configured from reusable FBs that can be exported to SIMULINK in the same way as application components, making it possible to analyze system properties via simulation. The discussion is illustrated with an industrial case study--a Medical Ventilator Control System, which has been used to validate the developed design and analysis methods.","Title: Computationally efficient retrieval-based tracking system and augmented reality for large-scale areas\nYear: 2011\n\nAbstract: We present a retrieval-based tracking system that requires less computational time and cost. The system tracks a user's location through a small portion of an image captured by the camera, and then refines the camera pose by propagating matchings to the whole image. Augmented information such as building names and locations will be delivered to the user. The progressive way to process image data not only can provide the user with location information at real-time speed, but more importantly, it reduces the feature matching time by limiting the searching ranges. The proposed system contains two parts, offline database building and online user tracking. The database is composed of image patches with features and location information. The images are captured at different locations of interests from different viewing angles and distances, and then these images are partitioned into smaller patches. The location of a user can be calculated by querying one or more patches of the captured image. Moreover, the system is capable to handle large occlusions in images due to the patch approach. Experiments show that the proposed tracking system is efficient and robust in many different environments.","Title: Component-Based Design of Software for Embedded Control Systems: The Medical Ventilator Case Study\nYear: 2009\n\nAbstract: COMDES-II is a component-based framework for distributed control systems featuring open architecture and predictable operation under hard real-time constraints. It has been experimentally validated in a number of case studies, including the Medical Ventilator Case Study discussed in the paper. The latter presents COMDES-II design models used to re-engineer the control system of an existing Medical Ventilator machine, and the resulting software implementation. The accumulated experience has helped reveal areas of possible improvement, and they have been taken into consideration while developing the latest version of the framework - COMDES-III.","Title: Complex Learning System for Behavior Factor based Data Analysis.\nYear: 2013\n\nAbstract: In this paper, we propose a complex learning system for data analysis that is based on behavior factor. This system combines features of both order based systems and order based data analysis framework. This system uses an appropriate behavior factor acquisition process, which is the weakest task in the current order and behavior factor based systems. As several research works have shown that data analysis is rather driven by domain behavior factor than by data, we have identified and analyzed the characters that distinguish behavior factor and orders from data for better determining the most components of the proposed system. This paper describes an approach that advocates the use of behavior factor order-based systems techniques for data analysis systems. In particular, we aim to make domain behavior factor explicit and separate from the system where will be used for data analysis. For representing domain behavior factor, we investigated a uniform and unified order representation form based on the creation of the environment component that stored information especially for the management of order and its quality. © 2013 ACADEMY PUBLISHER.","Title: Linear Relaying Scheme for MIMO Relay System With QoS Requirements\nYear: 2008\n\nAbstract: In this letter, we address the problem of fulfilling quality-of-service (QoS) requirements in a multiple-input multiple-output (MIMO) relay system, where a set of target signal-to-noise ratios (SNRs) should be attained on different substreams. By solving a two-step optimization problem, we obtain a power-efficient relaying scheme that can make the SNR requirements asymptotically fulfilled. A simple relay selection method is also proposed such that the relay-power consumption can be largely reduced when there is a large number of relays.","Title: A qualitative model of cross-lane inhomogeneities in traffic flow\nYear: 2004\n\nAbstract: The dilemma of traditionally quantitative methods in application to complex systems leads more and more researchers to emphasize the qualitative methods that can tackle the qualitative knowledge. Based on the concepts and ideas of qualitative reasoning, a preliminary qualitative method for modeling the traffic flow is proposed in this paper. Following new concepts, such as the homogenous measure index, which can be treated as an entropy to judge the homogeneity of traffic flow, a set of linear parameters-varying difference equations is used to describe the process of qualitative state transitions of the traffic flow. The procedures as well as the rationality of qualitative modeling for the traffic flow are illustrated by the data obtained from an actual traffic system-the Beijing Third Ring Road. Comparing the simulation results with actual data, it is proven that the results obtained by the proposed qualitative model coincide with the actual situation and the qualitative model can basically depict the nonhomogenous state transitions of traffic flow.","Title: Aircraft recognition in infrared image using wavelet moment invariants\nYear: 2009\n\nAbstract: Automatic Target Recognition (ATR) of infrared object has been taking a great interest to the researchers in recent years. ATR requires invariance of high cognition accuracy in translation, scaling and orientation, but classification of two-dimensional (2D) shapes despite of their position, size and orientation in infrared image remains a difficult problem. In this paper, a feature extraction method is proposed using Wavelet Moment Invariants (WMI). The very similar objects can be classified correctly by virtue of the wavelet moment with its multi-resolution properties. Compared with some other geometry moments, the classification rate and the recognition efficiency are improved with wavelet moments. As different wavelet basis will have different impacts to wavelet moment, it affects the efficiency of classification. Some important properties such as orthonomality, supported length and vanishing moments which affect the performance of wavelet moment are discussed in this paper. Through experimental analysis, a conclusion is obtained that symmetry, compactly supported wavelet has more high-performance, and using wavelet function with proper vanishing moments could effectively improve the efficiency of classification.","Title: Investigation on traffic flow competition between main road and on-ramp on urban freeway\nYear: 2012\n\nAbstract: Bottlenecks at highway or urban freeway are one of origins of traffic congestion. Based on empirical investigation on traffic data collected from Beijing urban freeway, we find that when traffic is dense, upstream flow and ramp flow are correlated significantly. Competitions between the two flows at vicinities of several on-ramps during a morning peak are studied. Based on these empirical observations, a flow competition model as an extension of CTM (cell transmission model) is developed. The proposed model focuses on reproducing correlated upstream flow and ramp flow in dense traffic. Both empirical data and simulation results point out that several traffic phenomena, such as capacity drop and spontaneous traffic breakdown, can be explained as results of such a competition.","Title: Design and Implementation of bus crew scheduling system using integrated casebased and rule-based reasoning\nYear: 2012\n\nAbstract: The bus crew scheduling problem (BCSP) is to assign drivers and conductors to daily crew duties that cover a set of schedules for buses of a public bus company during a period of time, e.g., a week. By combining case-based reasoning (CBR) and rule-based reasoning (RBR), this paper introduces the design and implementation of a bus crew scheduling system (BCSS). The current system works like this. Firstly, an inference mechanism integrating CBR and RBR is designed to obtain near-optimal solutions. Secondly, based on these nearoptimal solutions, a genetic algorithm is developed to produce better solutions. The practical applications show that the system is effective. © 2012 IEEE.","Title: ITS planning methodology for Chinese cities and its evaluation model\nYear: 2006\n\nAbstract: ITS Planning Methodology (IPM) is significant to guide the ITS Research &Development (R&D) strategically and systematically. This paper develops a general IPM and the ITS strategic objectives for Chinese cities, which creates a methodological framework to plan the urban ITS. During ITS planning, the ITS evaluation is a key component to make decisions. Based on the IPM and its objectives, for making up the deficiency of conventional evaluation methods, an ITS evaluation model by artificial neural network is built, and its feasibility has been proved by case study. The result shown by the planning and simulation is satisfied. It is practical and convenient to apply this model in the factual ITS planning. © 2006 IEEE.","Title: Study on Bus Route Evaluation System in Beijing Based on AHP\nYear: 2007\n\nAbstract: Bus route evaluation (BRE) of the public transit system in Beijing is requisite decision to regulate existing bus routes and reallocate transit resources for sustain operation. Since there wasn't a systematic BRE system for Beijing, firstly, this paper develops comprehensive BRE standards according to the status quo of Beijing's transit system, which includes 3 categories, 20 criterions in total. Secondly, based on method of Analytical Hierarchy Process (AHP), a BRE model is built, which integrates quantitative and qualitative attributes of routes. Finally, in terms of passenger flow data investigated, a case study of BRE among No. 7, No. 15, and No. 334 bus routes is carried out. It shows that the evaluation result by this BRE system is consistent with the actual condition of the transit system in Beijing. It is practicability and maneuverability to apply this model to regulate and optimize bus routes in Beijing.","Title: Empirical Investigations on Traffic Phase Transitions at Beijing Ring Road\nYear: 2007\n\nAbstract: In this paper, traffic features of urban ring road are investigated based on empirical data of Beijing 2\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">nd</sup>\n Ring Road. According to the concept of \"synchronized flow\" as well as the stability and synchronization among lanes around critical density, four traffic phases are identified: free flow, high-speed synchronized flow, low-speed synchronized flow and traffic jam. Moreover, spatio-temporal features of traffic flow based on these four phases are investigated empirically.","Title: Empirical Investigation on Phase Diagram at Urban Freeway with On-ramp\nYear: 2008\n\nAbstract: Bottlenecks at highway or urban freeway are one of origins of traffic congestion. Based on empirical investigation on field data of Beijing urban freeway, schematic phase diagram at on-ramp vicinity is developed and detailed phase transition processes are investigated. There are five phases in the phase diagram of on-ramp vicinity in connection with on-ramp flow and upstream flow, among which are two phases only observed in urban freeway traffic. It's also found that the empirical phase diagram developed in this paper is different from previous theoretical phase diagram of highway traffic. The boundaries of each phase are influenced by traffic demand at locations, such that empirical phase diagrams are vary in quantities at different locations. Moreover, according to investigation on empirical phase transition process, coherent moving flow, as a new phase observed in urban freeway flow in our previous work, is confirmed.","Title: Phase Transition of Urban Freeway Traffic Flow\nYear: 2008\n\nAbstract: At present, research on traffic flow theory has mainly focused on highway traffic, which is significantly different from urban freeway traffic. Traffic science is an \"empirical science\", and as such is it is based on empirical urban freeway traffic flow data. In this study, first four steady phases are identified in the flow-density plane of traffic flow: free flow, coherent-moving flow, synchronized flow and jam. Then, three modes of phase transition, i.e. spontaneous transition, propagating transition (PT) and induced transition (IT) are analyzed, and the judgment conditions as well as computable methods of PT and IT are discussed in detail. Finally, based on actual data of the Beijing urban freeway, an empirical analysis of phase transition from coherent-moving flow to synchronized flow, which is the process of \"smooth traffic\" transferring to \"congested traffic\", is presented to validate the concepts and methods proposed in this paper.","Title: Two-Way Network-Coded Relaying With Delay Constraint\nYear: 2015\n\nAbstract: Random channel fading may cause serious channel outage, and automatic repeat-request protocol has been widely used to mitigate packet loss by retransmitting the packet when the receiver fails to decode that packet. To restrict the transmission delay, a single packet might be retransmitted up to a limited number of times. For wireless two-way relay channels, the packet could be retransmitted by the original source node or the relay nodes, and the delay constraint might be imposed in a per-hop manner or end-to-end manner. For single-relay networks, we study the throughput of several relaying strategies including pure relaying and network-coded relaying subject to the delay constraint. We demonstrate that the binary xor-based network coding can greatly improve the system throughput, but the throughput gain is upper bounded. We also develop a near-optimum power allocation scheme to maximize the system throughput. For multirelay networks, we show that using digital network coding alone may cause some throughput loss when the frame length is much smaller than the number of relays, and we develop a hybrid network coding scheme to recover such throughput loss.","Title: Robust Image Matching With Line Context\nYear: 2013\n\nAbstract: We present a novel type of feature that is robust to challenging images that are mainly due to large illumination variations. The keypoints are detected so that they are repeatable with consistent scales in images of different illuminations, and the descriptors are formed by the context of neighboring line segments. Similar to many popular local features, the proposed feature is robust to occlusions, viewpoint changes and image clutters. Differently, while most state-of-the-art features can only handle small or monotonic illumination changes, our proposed feature is capable to match images with large and non-monotonic illumination variations. Through extensive experiments, the proposed feature is demonstrated to be robust and efficient in matching such challenging images.","Title: Outage probability optimization with equal and unequal transmission rates under energy harvesting constraints\nYear: 2013\n\nAbstract: In this paper, we study the power scheduling problem to optimize the outage probability with both equal and unequal transmission rates under energy harvesting constraints. In particular, we first model the average outage probability minimization problem over finite horizon, and then reformulate the problem by minimizing its upper bound, which converts the non-convex problem to a more efficient convex optimization problem. Next, we show the optimal power scheduling solution is related to the global minimum of an energy-and-time function which is defined as arithmetic average of harvested energy from current time slot to the arbitrary time slot in the future before the end of transmission. Based on such properties, we propose a Min-Average strategy which presents the optimal performance in upper bound of outage probability for equal and non-equal transmission rates. Simulation results show that, our power scheduling scheme achieves better outage performance compared to other alternative strategies, e.g, best-effort, fixed-saving and random saving strategies.","Title: A Heterogeneous Multi-Core Architecture with a Hardware Kernel for Control Systems.\nYear: 2012\n\nAbstract: Rapid industrialisation has resulted in a demand for improved embedded control systems with features such as predictability, high processing performance and low power consumption. Software kernel implementation on a single processor is becoming more difficult to satisfy those constraints. This paper presents a multi-core architecture incorporating a hardware kernel on FPGAs, intended for high performance applications in control engineering domain. First, the hardware kernel is investigated on the basis of a component-based real-time kernel HARTEX (Hard Real-Time Executive for Control Systems). Second, a heterogeneous multi-core architecture is investigated, focusing on its performance in relation to hard real-time constraints and predictable behavior. Third, the hardware implementation of HARTEX is designated to support the heterogeneous multi-core architecture. This hardware kernel has several advantages over a counterpart kernel implemented in software: higher-speed processing capability, parallel computation, and separation between the kernel itself and the applications being run. A microbenchmark has been used to compare the hardware kernel with the software kernel, and compare the kernel on the multi-core platform with the kernel on the single-core platform.","Title: Calibration of accelerometer with multicomponent inputs\nYear: 2014\n\nAbstract: For reducing the inconsistency of sensors' characteristics in laboratory and working conditions, calibration of an accelerometer with multicomponent inputs is introduced. After a review of current equipments which are capable of producing combined accelerations, we introduced a different apparatus which can offer simultaneous harmonic and constant linear accelerations. It consists of a vibration exciter mounted on a centrifuge. With reference to the output model of the machine, we present a calibration method based on the vibration rectification error of accelerometer. The method is a multi-orientation test scheme with four different configurations and numerically validated in this paper. More investigations are needed to improve the calibration of accelerometer with multicomponent accelerations.","Title: Accelerometer transverse sensitivity testing with double turntable centrifuge\nYear: 2014\n\nAbstract: An approach suitable for calibrating the transverse sensitivity of accelerometer at low-frequency is presented in this work. The method proposed here employs the double turntable centrifuge as the apparatus to provide standard reference accelerations. Numerical simulation and experimental investigation are done to validate the method. Testing results of a single-axis inertial accelerometer are consistent with the simulation. Typical `8' figure of the accelerometer transverse sensitivity is obtained. Both the simulation and experiment results show that the testing of the accelerometer transverse sensitivity of with the double turntable centrifuge is practicable..","Title: Non-fragile fuzzy dissipative static output feedback control for Markovian jump systems subject to actuator saturation.\nYear: 2016\n\nAbstract: In this paper, the problem of non-fragile fuzzy dissipative static output feedback control for Markovian jump systems subject to actuator saturation is considered. Based on Lyapunov theory and reciprocally convex combination lemma, sufficient conditions are obtained to ensure the closed-loop system to be stochastically stable and dissipative. Then, the non-fragile fuzzy static output feedback controller can be obtained by solving the LMIs. And the estimation of the largest domain of attraction for the system is solved as a LMI optimization problem. Finally, some numerical examples are provided to show the effectiveness of the proposed method.","Title: A novel wavelet-SVM short-time passenger flow prediction in Beijing subway system\nYear: 2015\n\nAbstract: In order to effectively manage the use of existing infrastructures and prevent the emergency caused by the large gathered crowd, the short-term passenger flow forecasting technology becomes more and more significant in the field of intelligent transportation system. However, there are few studies discussing how to predict different kinds of passenger flows in the subway system. In this paper, a novel hybrid model Wavelet-SVM is proposed, and it combines the complementary advantages of Wavelet and SVM models, and meanwhile overcomes their shortcomings respectively. The Wavelet-SVM forecasting approach consists of three important stages. The first stage decomposes the passenger flow data into different high frequency and low frequency series by wavelet. During the prediction stage, the SVM method is applied to learn and predict the corresponding high frequency and low frequency series. In the last stage, the diverse predicted sequences are reconstructed by wavelet. The experimental results show that the approach not only has the best forecasting performance compared with the state-of-the-art techniques but also appears to be the most promising and robust based on the historical passenger flow data in Beijing subway system and several standard evaluation measures.","Title: Design and implementation of wireless monitoring network for temperature-humidity measurement.\nYear: 2016\n\nAbstract: In order to overcome the shortcomings of existing wireless temperature-humidity monitoring systems, such as high-energy consumption, poor man–machine interaction, differential interference and no reverse real-time control etc., a novel real-time temperature-humidity monitoring system based on short distance wireless microwave communication is designed. In addition, some intelligent algorithms are briefly introduced in wireless communication for frequency assignment, improving energy efficiency and other resource allocation problems. This system uses the chip STC89C52 as the control chip, chip SHT11 as the data acquisition module, chip nRF905 as wireless transceiver module and chip MAX232 as the serial interface between the upper and the lower computer. The system requirements, system design, correlative hardware circuits, control flow chart and software design are depicted in details. This system can realize data acquisition, processing, transmission, control and display of temperature and humidity information. The system functions verification and performance test results show that this system has strong interference, low energy consumption and high precision. This system has great valuable, which has been applied in industrial and agricultural fields, such as greenhouse cultivation and laboratory storage.","Title: A Security-Critical Task Management Method for Distributed Real-Time Systems.\nYear: 2015\n\nAbstract: Security has become an important constraint in distributed real-time task system. For this paper, we give a security-critical distributed real-time task management model, then present a scheme for security-critical task management in the distributed real-time system, finally we propose an algorithm to solve the management problem in the distributed real-time system. We propose a security-critical distributed real-time task management model, and formulate the security-critical distributed real-time system task management issue into a shortest path problem. We solve the shortest path problem by using the improved Dijkstra algorithm. In addition, we validate the efficiency of the algorithm by simulation experiments.","Title: Finite-time dissipative control for singular T-S fuzzy Markovian jump systems under actuator saturation with partly unknown transition rates.\nYear: 2016\n\nAbstract: In this paper, we consider the problem of the static output feedback control for singular T-S fuzzy Markovian jump system with considering the influence of actuator saturation and partly unknown transition probabilities. Sufficient conditions are obtained to guarantee that the closed-loop is not only finite time bounded but also dissipative. The controller gain and the estimation of the domain of attraction can be solved by solving the linear matrix inequalities based optimization problem. Finally, numerical examples are illustrated for the effectiveness of the proposed method.","Title: A self-regulation traffic-condition-based route guidance strategy with realistic considerations: Overlapping routes, stochastic traffic, and signalized intersections\nYear: 2016\n\nAbstract: Variable message signs that provide various types of route guidance information have been widely deployed in large cities. To release proper information only using easily collected data, a simple traffic-condition-based (TCB) route guidance strategy was recently proposed. The strategy works based on the estimation of free-flow and congested traffic conditions and is capable of approximating user optimal equilibrium stably. Due to little consideration of the complexity of urban road networks, the TCB strategy is still away from field applications in urban areas. To further push the strategy toward field tests, this article improves the TCB strategy in the following aspects: supplementing the strategy with a self-regulation ability by considering existing traffic conditions; decomposing link capacity to solve the problem of overlapping routes by comparing link capacity on alternative routes; coping with stochastic traffic; and the impact of signalized intersections by utilizing aggregated data. A scenario for an urban road network in Beijing, China, is simulated to test the improved strategy, and the simulation results clearly indicate the effectiveness of the proposed improvements. The improvements extend the TCB strategy on moderately complicated urban road networks, and still have the advantages of simple diversion rules, easily obtained input data, and stable and effective diversion processes.","Title: Mapping to Cells: A Simple Method to Extract Traffic Dynamics from Probe Vehicle Data.\nYear: 2017\n\nAbstract: In the era of big data, mining data instead of collecting data are a new challenge for researchers and engineers. In the field of transportation, extracting traffic dynamics from widely existing probe vehicle data is meaningful both in theory and practice. Therefore, this article proposes a simple mapping-to-cells method to construct a spatiotemporal traffic diagram for a freeway network. The method partitions a network region into small square cells and represents a real network inside the region by using the cells. After determining the traffic flow direction pertaining to each cell, the spatiotemporal traffic diagram colored according to traffic speed can be well constructed. By taking the urban freeway in Beijing, China, as a case study, the mapping-to-cells method is validated, and the advantages of the method are demonstrated. The method is simple because it is completely based on the data themselves and without the aid of any additional tool such as Geographic Information System software or a digital map. The method is efficient because it is based on discrete space-space and time-space homogeneous cells that allow us to match the probe data through basic operations of arithmetic. The method helps us understand more about traffic congestion from the probe data, and then aids in carrying out various transportation researches and applications.","Title: Distributed Optimization of Hierarchical Small Cell Networks: A GNEP Framework.\nYear: 2017\n\nAbstract: Deployment of small cell base stations (SBSs) overlaying the coverage area of a macrocell BS (MBS) results in a two-tier hierarchical small cell network. Cross-tier and inter-tier interference not only jeopardize primary macrocell communication but also limit the spectral efficiency of small cell communication. This paper focuses on distributed interference management for downlink small cell networks. We address the optimization of transmit strategies from both the game theoretical and the network utility maximization (NUM) perspectives and show that they can be unified in a generalized Nash equilibrium problem (GNEP) framework. Specifically, the small cell network design is first formulated as a GNEP, where the SBSs and MBS compete for the spectral resources by maximizing their own rates while satisfying global quality of service (QoS) constraints. We analyze the GNEP via variational inequality theory and propose distributed algorithms, which only require the broadcasting of some pricing information, to achieve a generalized Nash equilibrium (GNE). Then, we also consider a nonconvex NUM problem that aims to maximize the sum rate of all BSs subject to global QoS constraints. We establish the connection between the NUM problem and a penalized GNEP and show that its stationary solution can be obtained via a fixed point iteration of the GNE. We propose GNEP-based distributed algorithms that achieve a stationary solution of the NUM problem at the expense of additional signaling overhead and complexity. The convergence of the proposed algorithms is proved and guaranteed for properly chosen algorithm parameters. The proposed GNEP framework can scale from a QoS constrained game to an NUM design for small cell networks by trading off signaling overhead and complexity.","Title: Graphical Human–Machine Interactive Approach for Integrated Bus Transit Scheduling: Lessons Gained From a Large Bus Company\nYear: 2017\n\nAbstract: This paper describes an integrated human–machine interactive bus transit scheduling system developed for the Beijing Public Transport Holdings (Group) Company, Ltd. (BPTG), one of the largest bus companies in the world. The system, which is based on a highly informative deficit function graphical optimization technique, allows schedulers to select computer-generated improvements or interject their own practical considerations. The initial implementation of the new system in two subcompanies of BPTG demonstrates its effectiveness and efficiency with many good features, such as improved integration and coordination of scheduling vehicles and crews, reduced vehicle fleet size, and reduced number of crew duties.","Title: Erasing Lane Changes From Roads: A Design of Future Road Intersections.\nYear: 2018\n\nAbstract: Imagine in the future that autonomous vehicles coordinated and guided by signal-free autonomous intersections are able to pass through the intersections immediately after the vehicles in the conflicting direction leave. Meanwhile, with the coordination of the autonomous intersections, autonomous vehicles on any approaching lane are able to turn onto any downstream lane, expecting that driving in s...","Title: Facial semantic descriptors based on information granules.\nYear: 2019\n\nAbstract: In this paper, we investigate a granular data description for facial components in which a characterization of facial components is presented by a collection of information granules. Firstly, the facial landmark detector is utilized to extract facial components automatically. Secondly, semantic concepts are formed by involving various mechanisms of fuzzy clustering based on these detected landmarks. A collection of numeric prototypes can be sought as a blueprint of the descriptors. Consequently, the information granules are being formed around the prototypes that are engaged by the fundamental ideas of Granular Computing, especially the principle of justifiable granularity. Multiple experiments on Multi-PIE facial database illustrate the proposed facial semantic descriptors based on information granules not only can characterize the key semantics of facial components of data, but also can improve the semantic classification performance in comparison with human perception.","Title: Analysis and Prediction of Regional Mobility Patterns of Bus Travellers Using Smart Card Data and Points of Interest Data\nYear: 2019\n\nAbstract: Mobility patterns at region level can provide more macroscopic and intuitive knowledge on how people gather in or depart from the region. However, the analysis and prediction of regional mobility patterns have yet to be effectively addressed. In light of this, using smart card data (SCD) and points of interest (POI) data, a multi-step methodology which integrates the inner-restricted fuzzy C-means clustering, nonnegative tensor factorization and artificial neural network are proposed and implemented in this paper. It overcomes the difficulties in region division, pattern extraction, and prediction. The bus SCD and POI data in Beijing city are utilized for proving the usefulness of the methodology. The regional mobility patterns of bus travellers in Beijing city are extracted from the third-order tensors involving 1110 regions, 34 time slots, and 7 days of the week. The analyzed results show that the proposed methodology has a good performance on predicting the regional mobility patterns based on the regional properties. Furthermore, by considering both of the regional boarding and alighting patterns, the predictions of the regional aggregation pattern can also be achieved. These research achievements can not only provide a deep insight on the human mobility patterns at region level, but also support the evidence-based and forward-looking urban planning and intelligent transportation management.","Title: Vehicle sensor data-based analysis on the driving style differences between operating indoor simulator and on-road instrumented vehicle\nYear: 2019\n\nAbstract: Indoor simulator and on-road instrumented vehicle are the most popular ways to analyze driving behaviors by using collected Vehicle Sensor Data (VSD). However, for a same driver, the driving performance could be different in the real world and in the simulated world. Even though many studies have been conducted to discover the differences of driving behaviors in these two circumstances, little research has focused on analyzing the differences in driving style, which can provide more integrated knowledge of a driver from the natural structure, stimulus–response mechanism, of driving behaviors. Therefore, in this paper, the driving styles in both the real world and the simulated world are extracted by implementing the nonnegative matrix factorization method on the collected VSD data. Through this analysis, the driving style differences can be quantitatively described and discussed in detail. It is found that the drivers tend to be more unstable and sometimes aggressive when driving the simulator and the deviation in the perception of temporal gap in two circumstances is also discovered. The research findings are particularly valuable to calibrate the driving simulator and construct more reliable driving behavior models.","Title: Probability Distribution of Represented Sources in Conversations of Adults and Children\nYear: 2020\n\nAbstract: Based upon a taxonomy of represented sources, this paper investigates the quantitative features of two groups - one comprised of adults and the other of seven-year-old children - that employ a variety of sources in everyday representation. Results indicate that: 1) the overall probability distributions of represented sources used by both groups fit well to the modified right truncated Zipf-Alekseev distribution; 2) the R-2 value of the adult group is lower than that of the child group, largely due to the prevalence of non-present non-specified human references by the adults; 3) the values of fitting parameters a and n differ significantly between the two groups; 4) while representing from sources is an extralinguistic phenomenon, it nevertheless reflects the similar quality of language (i.e. a human-driven complex adaptive system), and it also offers a better understanding of the quantitative features of this phenomenon. In summary, this study presents the results of several preliminary attempts to study a specific type of extralinguistic phenomenon from a quantitative perspective.","Title: Finite-Time Filtering for Discrete-Time Singular Markovian Jump Systems with Time Delay and Input Saturation\nYear: 2019\n\nAbstract: The paper is discussed with the problem of finite-time H-infinity filtering for discrete-time singular Markovian jump systems (SMJSs). The systems under consideration consist of time-varying delay, actuator saturation and partly unknown transition probabilities. We pay attention to the design of a H-infinity filtering which ensures the filtering error systems to be singular stochastic finite-time boundedness. By employing an adequate stochastic Lyapunov functional together with a class of linear matrix inequalities (LMIs), a sufficient condition is firstly established, which guarantees the systems to achieve our goal and satisfy a prescribed H-infinity attenuation level in the given finite-time interval. Considering the above conditions, a distinct presentation for the requested H-infinity filter is given. Finally, two numerical examples add to a dynamical Leontief model of economic systems are presented to illustrate the validity of the developed theoretical results.","Title: Semantics characterization for eye shapes based on directional triangle-area curve clustering\nYear: 2019\n\nAbstract: In this paper, we present a novel approach to address the problem of eye shape characterization via curve representation. Firstly, a directional triangle-area curve representation method (DTAR) is presented for this aim. Equipped with DTAR, the shape similarities between two eyes can be measured by the similarities between two corresponding DTAR curves. Secondly, in order to exploit the underlying information of eye shapes, a curve clustering algorithm is utilized to automatically discover a set of eye shape prototypes. Consequently, a semantics extraction method for eye shapes is proposed in terms of seven reference eye shapes. Finally, in order to validate the consistency of the clustering results and the extracted semantics, extensive experiments on AR and BU4DFE databases are designed and conducted, and all the results demonstrate the effectiveness of the proposed DTAR curve representation and the semantics extraction method.","Title: Dissipative control for singular T-S fuzzy Markov jump systems under quantized feedback\nYear: 2019\n\nAbstract: In this paper, we investigate the design problem of the feedback controller for singular T-S fuzzy Markov jump system considering the influence of uncertainties, time-delay, and signal quantization. A sufficient condition is obtained to guarantee the closed-loop system not only stochastically admissible but also dissipative. Subsequently, the dissipative quantized controller is designed by solving the linear matrix inequalities (LMIs), which takes into consideration the nonrepresentational energy, storage function, and supply rate for the disturbance weaken and gives a unified framework that can include the existing results for passivity and H-infinity controllers as special cases for the considered system. Finally, numerical examples have illustrated the effectiveness of the proposed method.","Title: Generative character inpainting guided by structural information\nYear: 2021\n\nAbstract: Character inpainting is an attractive and challenging task, especially for Chinese calligraphy characters with complex structures and styles. The diversity of Chinese calligraphy styles has created its unique artistic beauty, but specific style features will lead to obvious differences in style and stroke details while recovering. Most current methods are restricted to recover specific characters already present in the training set and retrain the model when recovering characters of new styles. Moreover, these methods are based on edge recovery, which requires the location of the masked area. In this paper, we propose a novel structure-guided generative framework guided by prototype character, which can not only adapt to multiple style fonts but also overall recover glyph structure and strokes without masked information by inferring the style representation. In this case, our method can recover new style characters, which is the first attempt for character inpainting without parameter retraining. Experimental results demonstrate that our method has generalizability and superiority in most application scenarios, compared with several state-of-the-art character inpainting methods.","Title: A Novel Multi-channel Random Competitive MAC Protocol Based on Channel Load Prediction Mechanism for ATNs\nYear: 2021\n\nAbstract: For the dramatic decrease of network performance under heavy traffic load in existing medium access control (MAC) protocols in airborne tactical networks, a multi-channel random competitive MAC protocol based on a novel statistical prediction-based access decision mechanism is proposed in this paper. The MAC protocol mainly consists of the channel load prediction mechanism, the packet access decis...","Title: Intelligent Smart Marine Autonomous Surface Ship Decision System Based on Improved PPO Algorithm\nYear: 2022\n\nAbstract: With the development of artificial intelligence technology, the behavior decision-making of an intelligent smart marine autonomous surface ship (SMASS) has become particularly important. This research proposed local path planning and a behavior decision-making approach based on improved Proximal Policy Optimization (PPO), which could drive an unmanned SMASS to the target without requiring any human experiences. In addition, a generalized advantage estimation was added to the loss function of the PPO algorithm, which allowed baselines in PPO algorithms to be self-adjusted. At first, the SMASS was modeled with the Nomoto model in a simulation waterway. Then, distances, obstacles, and prohibited areas were regularized as rewards or punishments, which were used to judge the performance and manipulation decisions of the vessel Subsequently, improved PPO was introduced to learn the action-reward model, and the neural network model after training was used to manipulate the SMASS's movement. To achieve higher reward values, the SMASS could find an appropriate path or navigation strategy by itself. After a sufficient number of rounds of training, a convincing path and manipulation strategies would likely be produced. Compared with the proposed approach of the existing methods, this approach is more effective in self-learning and continuous optimization and thus closer to human manipulation.","Title: Health diagnosis of NC machine tool from user's perspective\nYear: 2022\n\nAbstract: NC machines' health monitoring is important for manufacturing enterprises. In this paper, we propose a scheme to do the monitoring and diagnosis mainly via collecting the internal data generated by the inside sensors of NC machine tool. Then these data are analyzed by Principal Component Analysis (PCA) method to determine the health status. The experimental results show that this method has certain applicability and effectiveness for the health diagnosis of NC machine tools, and is of good value for large manufacturing enterprises, of which core competitiveness resides on the sufficient operation of these machines.","Title: Spectrum Sharing in UAV-Assisted HetNet Based on CMB-AM Multi-Agent Deep Reinforcement Learning\nYear: 2022\n\nAbstract: Unmanned aerial vehicle (UAV) assisted heterogeneous network (HetNet) is a promising solution to outdoor hotspots. This poster proposes a coordination-mini-batch with action mask (CMB-AM) multi-agent deep reinforcement learning (DRL) based resource allocation scheme for uplink spectrum sharing in a UAV-assisted two-tier heterogeneous network (Het-Net). We utilize a centralized training and distributed execution mechanism and consider the correlation among actions to make the agents collaborate implicitly. Due to independent state and collective reward design, our resource allocation scheme can be robust and scalable to the varying number of agents. Evaluation shows that the proposed scheme achieves better performance on the aspects of sum capacity, model applicability, and training stability than other baseline schemes.","Title: A Two-Phase Optimization Model for Autonomous Electric Customized Bus Service Design\nYear: 2022\n\nAbstract: Motivated by the requirements of highly effective customized bus (CB) service and by the rapid growth of autonomous electric vehicles (AEVs), this paper studies a new optimization model for the autonomous electric customized bus (AECB) service, aiming at minimizing operating costs and improving vehicles' efficient use. The proposed model contains two phases: (i) optimization of the vehicle routing, charging operation and passenger-to-vehicle assignment for the fixed travel demands, and (ii) re-optimization of the service according to real-time dynamic travel requests. A solution approach is developed to address the proposed model based on adaptive large neighborhood search (ALNS). The extensive empirical analysis, conducted by considering real-world data on a large-scale instance, demonstrates the efficiency of the proposed approach and the quality of the generated solutions."],"string":"[\n \"Title: Intelligent Transportation Systems\\nYear: 2006\\n\\nAbstract: This Works in Progress department discusses 10 ongoing intelligent transportation systems projects. TIME, Sentient Transport, Electric-Vehicle Terminal, DynaChina, and TrafficView focus on traffic and vehicular data collection, transmission, and analysis. Other projects aim to provide intelligent-copilot services for drivers; focus on asset identification and data collection for railroad environments; are building application development environments for automobiles; and are designing a multimodal biometric identification system for travel documents. This department is part of a special issue on Intelligent Transportation.\",\n \"Title: Including and optimizing shape parameters in Doo-Sabin subdivision surfaces for interpolation\\nYear: 2007\\n\\nAbstract: This paper considers the problems of how to introduce shape parameters into recursive subdivision schemes for additional shape control and how to find appropriate values of shape parameters to improve the quality of subdivision surface shapes. Following Brunet, we restrict our discussion to the algorithm that constructs a Doo-Sabin subdivision surface to interpolate the vertices of an input polyhedron with arbitrary topology. While Brunet defined one so-called \\\"shape handle\\\" for each vertex of the initial polyhedron, which is used to scale the type-V face obtained after the first step of the subdivision process, we introduce three shape parameters for each vertex: one for the scale and the other two for the orientation of the type-V face. This gives more degrees of freedom to optimize the shape of the result interpolatory surface. We develop a genetic algorithm to compute the optimal set of shape parameters such that a \\\"fairness\\\" measure of the surface is minimized. Examples are provided to demonstrate the effects of the optimal shape parameters on the final interpolatory surfaces.\",\n \"Title: View-Based 3D Model Transmission via Mesh Segmentation\\nYear: 2007\\n\\nAbstract: For network-based graphics applications, a key challenge is how to efficiently transmit complex three-dimensional (3D) models over bandwidth-limited communication channels such as wireless links. Most existing 3D mesh coding algorithms do not consider the view-dependent rendering issue, and therefore result in transmitting unnecessary portions of 3D mesh models which leads to the waste in precious network bandwidth. In this paper, we propose a novel view-dependent 3D model transmission scheme, where a 3D model is partitioned into a number of segments, each segment is then independently coded using the MPEG-4 3DMC coding algorithm, and finally only the visible segments are selected and delivered to the client. Such a view-based 3D model transmission is able to substantially save the transmission bandwidth and therefore has a significant impact on wireless network based graphics applications.\",\n \"Title: Design and Implementation of Bus Monitoring System Based on GPS for Beijing Olympics\\nYear: 2009\\n\\nAbstract: To guarantee the safety of public transport and effectiveness in dispatching buses, overall solution on Beijing Bus Monitoring System (BJ-BMS) based on GPS is put forward in this paper. The system is composed of communication control and GIS subsystems, each of which was independently developed in the beginning and integrated in the end.The key technologies of the system are described in detail. In addition to some fundamental functions such as real-time monitoring, some featured functions tightly combined with the daily operations in Beijing Bus Company are realized in the BJ-BMS. Finally, the status of system implementation and maintenance are introduced, which have proven to be very effective in practical applications during 2008 Beijing Olympics.\",\n \"Title: Robust pose estimation in untextured environments for augmented reality applications\\nYear: 2009\\n\\nAbstract: We present a robust camera pose estimation approach for stereo images captured in untextured environments. Unlike most of existing registration algorithms which are point-based and make use of intensities of pixels in the neighborhood, our approach imports line segments in registration process. With line segments as primitives, the proposed algorithm is capable to handle untextured images such as scenes captured in man-made environments, as well as the cases when there are large viewpoint changes or illumination changes. Furthermore, since the proposed algorithm is robust to large base-line stereos, there are improvements on the accuracy of 3D points reconstruction. With well-calculated camera pose and object positions in 3D space, we can embed virtual objects into existing scene with higher accuracy for realistic effects. In our experiments, 2D labels are embedded in the 3D scene space to achieve annotation effects as in AR.\",\n \"Title: Diversity Analysis of Non-Coherent Wireless Network Coding.\\nYear: 2013\\n\\nAbstract: Network coding has been widely used in the wireless uplink. To do coherent detection at the receiver, channel estimation is performed to collect the channel state information (CSI). For multi-user channels, the channel estimation overhead is sometimes formidable and may even outweigh the network coding gain. To address this issue, we study the non-coherent network coding in this work. Both the ana...\",\n \"Title: Estimation of camera pose with respect to terrestrial LiDAR data\\nYear: 2013\\n\\nAbstract: In this paper, we present an algorithm that is to estimate the position of a hand-held camera with respect to terrestrial LiDAR data. Our input is a set of 3D range scans with intensities and one or a set of 2D uncalibrated camera images of the scene. The algorithm that automatically registers range scans and 2D images is composed of following steps. In the first step, we project the terrestrial LiDAR onto 2D images according to several preselected viewpoints. Intensity-based features such as SIFT are extracted from these projected images and these features are projected back onto the LiDAR data to obtain their 3D positions. In the second step, we estimate the initial pose of given 2D images from feature correspondences. In the third step, we refine the coarse camera pose obtained from the previous step through iterative matchings and optimization process. We presents results from experiments in several different urban settings.\",\n \"Title: Outlier Detection of Handover Data for Inner-Suburban Freeway Traffic Information Estimation Using Mobile Probes\\nYear: 2011\\n\\nAbstract: Mobile probes provide a supplementary means of traffic information estimation for inner-suburban freeways in the major big cities in China. Lack of sufficient participants with GPS-based smart phones at the moment, handover-based location solution, one of GSM-based location solutions, was tentatively employed in this paper. Since handover data currently cannot have the same location performance with GPS data, low location accuracy has been a great challenge for traffic information estimation. To improve the estimated accuracy of travelling speed using mobile probes, an outlier detection algorithm of handover data is developed for identifying those handover links with large estimated errors. The developed outlier detection algorithm contains two steps, outlier detection of individual handover link and outlier detection of linked handover links. LS-SVM ensemble classifier is employed in the first step and a statistical-based algorithm is employed in the second step. Evaluations of the developed algorithm were finally studied using field data collected in a preliminary field test in a stretch of inner suburban freeway in Beijing, China.\",\n \"Title: Developing a Toolset Supporting the Construction of Reusable Components for Embedded Control Systems\\nYear: 2010\\n\\nAbstract: Reusing software components for embedded control applications enhances product quality and reduces time to market when appropriate (formal) methodologies and supporting toolsets are available. That is why industrial companies are interested in developing trusted, in-house reusable components for specific areas of application. This creates a demand for tools supporting the construction of reusable components, with various artifacts produced automatically out of component models and deposited into a repository. Thus, pre-fabricated and ready to use components can be reused to fabricate applications. That demand can be satisfied by a highly customized toolset providing an integrated development environment for rapid graphical component specification, component validation, automatic generation of artifacts and documentation. The paper presents a possible solution for creating a customized toolset based on open-source technology, in accordance with industrial requirements, as well as the approach used to engineer a toolset supporting component development for embedded control applications.\",\n \"Title: Adaptive fault-tolerant output-feedback control of LTI systems subject to actuator saturation\\nYear: 2009\\n\\nAbstract: This paper is concerned with the problem of designing adaptive fault-tolerant output-feedback controllers for linear time-invariant (LTI) systems with actuator saturation. By combining the linear matrix inequality (LMI) approach for output-feedback controllers design and adaptive method, a method of designing adaptive reliable output-feedback controllers is proposed, where the controller parameter matrices are updated automatically to compensate the controller failures effects on systems based on the online estimations of eventual faults. The designs are developed in the framework of LMI approach, which can enlarge the domain of asymptotic stability of closed-loop systems in the cases of actuator saturation and actuator failures. An example is given to illustrate the efficiency of the design method.\",\n \"Title: Segmentation-Based View-Dependent 3-D Graphics Model Transmission\\nYear: 2008\\n\\nAbstract: For wireless network based graphics applications, a key challenge is how to efficiently transmit complex 3-D models over bandwidth-limited wireless channels. Most existing 3-D mesh transmission systems do not consider such a view-dependent delivery issue, and thus transmit unnecessary portions of 3-D mesh models, which leads to the waste in precious wireless network bandwidth. In this paper, we propose a novel view-dependent 3-D model transmission scheme, where a 3-D model is partitioned into a number of segments, each segment is then independently coded using the MPEG-4 3DMC coding algorithm, and finally only the visible segments are selected and delivered to the client. Moreover, we also propose analytical models to find the optimal number of segments so as to minimize the average transmission size. Simulation results show that such a view-based 3-D model transmission is able to substantially save the transmission bandwidth and therefore has a significant impact on wireless graphics applications.\",\n \"Title: Sn1-Sn2 And Sn2-Sn3 Mechanistic Changes Revealed By Transition States Of The Hydrolyses Of Benzyl Chlorides And Benzenesulfonyl Chlorides\\nYear: 2014\\n\\nAbstract: Hydrolysis reactions of benzyl chlorides and benzenesulfonyl chlorides were theoretically investigated with the density functional theory method, where the water molecules are explicitly considered. For the hydrolysis of benzyl chlorides (para-ZC(6)H(4)CH(2)Cl), the number of water molecules (n) slightly influences the transition-state (TS) structure. However, the para-substituent (Z) of the phenyl group significantly changes the reaction process from the stepwise (S(N)1) to the concerted (S(N)2) pathway when it changes from the typical electron-donating group (EDG) to the typical electron-withdrawing one (EWG). The EDG stabilizes the carbocation (MeOC6H4CH2+), which in turn makes the S(N)1 mechanism more favorable and vice versa. For the hydrolysis of benzenesulfonyl chlorides (para-ZC(6)H(4)SO(2)Cl), both the Z group and n influence the TS structure. For the combination of the large n value (n>9) and EDG, the S(N)2 mechanism was preferred. Conversely, for the combination of the small n value and EWG, the S(N)3 one was more favorable. (c) 2014 Wiley Periodicals, Inc.\",\n \"Title: Implications of collection/delivery points for transport and logistics.\\nYear: 2011\\n\\nAbstract: Failed first-time home deliveries may result in carrier's repeated delivery journeys and also consumer's trips to retrieve their failed deliveries from the carrier's depot. Home shopping is rapidly becoming a significant generator of logistics activity, and efforts are being devoted to identify the transport and environmental implications of those failed home deliveries. The attended collection/delivery point (CDP) concept is one solution to deal with the first-time delivery failures, using a variety of locations (for example, convenience stores, post offices) as alternative addresses to receive deliveries. Using two databases of households from across Winchester and West Sussex (UK), this article confirms that certain benefits might accrue from using networks of Local Collect post offices, supermarkets and railway stations as CDPs, compared with the traditional delivery method where the carrier may make several redelivery attempts to the home, with the customer making a personal trip to the carrier's depot in the event that these attempts also fail.\",\n \"Title: Efficient matchings and mobile augmented reality\\nYear: 2012\\n\\nAbstract: With the fast-growing popularity of smart phones in recent years, augmented reality (AR) on mobile devices is gaining more attention and becomes more demanding than ever before. However, the limited processors in mobile devices are not quite promising for AR applications that require real-time processing speed. The challenge exists due to the fact that, while fast features are usually not robust enough in matchings, robust features like SIFT or SURF are not computationally efficient. There is always a tradeoff between robustness and efficiency and it seems that we have to sacrifice one for the other. While this is true for most existing features, researchers have been working on designing new features with both robustness and efficiency. In this article, we are not trying to present a completely new feature. Instead, we propose an efficient matching method for robust features. An adaptive scoring scheme and a more distinctive descriptor are also proposed for performance improvements. Besides, we have developed an outdoor augmented reality system that is based on our proposed methods. The system demonstrates that not only it can achieve robust matchings efficiently, it is also capable to handle large occlusions such as passengers and moving vehicles, which is another challenge for many AR applications.\",\n \"Title: Efficient matchings in augmented reality application\\nYear: 2012\\n\\nAbstract: With fast growing popularity of smart phones in recent years, augmented reality (AR) becomes more demanding than ever before. However, one of main challenges is that while features like SIFT or SURF are robust in matchings, they are not computationally efficient. In this paper, we propose an efficient matching method for robust features. A distinctive descriptor is also proposed for performance improvements. Besides, we have developed an outdoor augmented reality system that is based on our proposed methods. The system demonstrates that not only it can achieve robust matchings efficiently, it is also capable to handle large occlusions such as passengers and moving vehicles.\",\n \"Title: Capacity Based Fast Receive Antenna Subset Selection In Mimo System\\nYear: 2008\\n\\nAbstract: In this letter, we develop a two-step receive antenna selection method to maximize channel capacity. Different from previous work, we first derive a lower bound on capacity based on Hadamard inequality and arithmetic-geometric mean inequality, which is then used to iteratively drop the worst-performing antennas according to their measure. The recursive nature of this method helps to largely reduce the computational complexity.\",\n \"Title: Error performances of multiple access system using analog network coding\\nYear: 2012\\n\\nAbstract: In this work, we study the error performances of the multiple access system using analog network coding (ANC), where all the users broadcast their data to the relays and destination simultaneously in the first phase, and the relays forward the source messages that have been mixed in the air in the second phase. Depending on the type of relay power constraint, both the variable gain relaying and fixed gain relaying are considered. We show that the error rates of both schemes scale as O(log P/P2) at high signal-to-noise ratio (SNR), where P is the transmitted power. We also show that the error performance is dominated by the relay-destination channel, thus the best relay position should be close to the destination. We also demonstrate that ANC may be outperformed by the conventional amplify-and-forward scheme when the data rate is low and the user number is not large. Finally, we propose a relay selection strategy based on Min-Max criterion that can achieve full diversity when there are multiple relays.\",\n \"Title: Illumination and view dependent progressive transmission of semi-regular meshes with subdivision connectivity\\nYear: 2007\\n\\nAbstract: For wireless network based graphics applications, a key challenge is how to efficiently transmit complex 3D models over bandwidth-limited wireless channels. Recently, several view-dependent 3D progressive mesh transmission schemes have been proposed, which save the transmission bandwidth through only delivering the visible portions of a mesh model. In this paper, we propose to incorporate the illumination effects into the existing view-depend progressive mesh transmission system to further improve the performance. In particular, we propose a novel distortion model, which consists of both illumination distortion and geometry distortion. We further simplify the distortion model in order to compute the rate-distortion function for each segment of a mesh model in a fast manner. Based on our proposed simplified distortion model, given the viewing and lighting parameters, we are able to optimally allocate bits among different segments in real time. Experimental results show that significant quality improvement can be achieved by taking into account the illumination effects.\",\n \"Title: Clustering based space-time network coding\\nYear: 2012\\n\\nAbstract: Many-to-one communication is a challenging problem in practice due to channel fading and multi-user interferences. In this work, a new protocol that leverages spatial diversity through space-time network coding is proposed. The N source nodes are first divided into K clusters, each having Q nodes, and the clusters send data successively in a time-division multiple access way. Each node behaves as a decode-and-forward relay to other clusters, and uses linear coding to combine the local symbol and the relayed symbols. To separate the multi-source signals, each node has a unique signature waveform, and linear decorrelator is used at the receivers. Both the exact Symbol Error Rate (SER) and the asymptotic SER at high signal-to-noise ratios of the M-ary phase-shift keying signal are studied then. It is shown that a diversity order of (N - Q + 1) can be achieved with a low transmission delay of K time slots, which is more bandwidth efficient than the existing protocols. Simulation results also justify the performance gains.\",\n \"Title: Ovarian cancer detection from metabolomic liquid chromatography/mass spectrometry data by support vector machines.\\nYear: 2009\\n\\nAbstract: The majority of ovarian cancer biomarker discovery efforts focus on the identification of proteins that can improve the predictive power of presently available diagnostic tests. We here show that metabolomics, the study of metabolic changes in biological systems, can also provide characteristic small molecule fingerprints related to this disease.In this work, new approaches to automatic classification of metabolomic data produced from sera of ovarian cancer patients and benign controls are investigated. The performance of support vector machines (SVM) for the classification of liquid chromatography/time-of-flight mass spectrometry (LC/TOF MS) metabolomic data focusing on recognizing combinations or \\\"panels\\\" of potential metabolic diagnostic biomarkers was evaluated. Utilizing LC/TOF MS, sera from 37 ovarian cancer patients and 35 benign controls were studied. Optimum panels of spectral features observed in positive or/and negative ion mode electrospray (ESI) MS with the ability to distinguish between control and ovarian cancer samples were selected using state-of-the-art feature selection methods such as recursive feature elimination and L1-norm SVM.Three evaluation processes (leave-one-out-cross-validation, 12-fold-cross-validation, 52-20-split-validation) were used to examine the SVM models based on the selected panels in terms of their ability for differentiating control vs. disease serum samples. The statistical significance for these feature selection results were comprehensively investigated. Classification of the serum sample test set was over 90% accurate indicating promise that the above approach may lead to the development of an accurate and reliable metabolomic-based approach for detecting ovarian cancer.\",\n \"Title: Augmented distinctive features for efficient image matching\\nYear: 2011\\n\\nAbstract: Finding corresponding image points is a challenging computer vision problem, especially for confusing scenes with surfaces of low textures or repeated patterns. Despite the well-known challenges of extracting conceptually meaningful high-level matching primitives, many recent works describe high-level image features such as edge groups, lines and regions, which are more distinctive than traditional local appearance based features, to tackle such difficult scenes. In this paper, we propose a different and more general approach, which treats the image matching problem as a recognition problem of spatially related image patch sets. We construct augmented semi-global descriptors (ordinal codes) based on subsets of scale and orientation invariant local keypoint descriptors. Tied ranking problem of ordinal codes is handled by increasingly keypoint sampling around image patch sets. Finally, similarities of augmented features are measured using Spearman correlation coefficient. Our proposed method is compatible with a large range of existing local image descriptors. Experimental results based on standard benchmark datasets and SURF descriptors have demonstrated its distinctiveness and effectiveness.\",\n \"Title: SUE Model Based on a Reliability-Admissible Reasonable Route Set\\nYear: 2012\\n\\nAbstract: This paper proposes a reliability-admissible filtering mechanism to generate the reasonable route set for the traditional SUE model. This mechanism still takes into account traveler's cost-susceptivity, which is able to dispel the impact of dimension on the traffic assignment. The filtering formula is presented and further estimated based on the Gumbel distribution assumption for the route disutility. The corresponding Logit-based SUE model and MSA-based algorithms for the multi-class case are presented, and are verified via numerical examples. Numerical results illustrate that the hazardous routing behavior will cause heavy traffic crowding and reduce the utilization efficiency of network. In addition, a reasonable structure of travel demand will contribute to alleviate the urban traffic congestion.\",\n \"Title: Performance Analysis of Two-Way Relaying with Non-Coherent Differential Modulation.\\nYear: 2011\\n\\nAbstract: This work focuses on a two-way denoise-and-forward relaying system using non-coherent Differential Binary Phase-Shift Keying (DBPSK) modulation, which has the well-defined relay denoising function when channel state information is unknown. We first design the relay denoising function and source decoders using Maximum Likelihood (ML) principles for the general case with K parallel relays. As the ML...\",\n \"Title: Image relighting and matching with illumination information\\nYear: 2012\\n\\nAbstract: In recent years, interest point based feature such as SIFT and SURF are widely used for image matchings. While these features are robust to changes in scales, rotations, and local geometric deformations, they are usually less able to simultaneously handle viewpoint changes and large illumination changes. In this paper, we will cope with this challenging problem. The basic idea is to relight one of the two images so that the image has similar illumination conditions as the other one. After relighting process, the point based features become effective again in the matching process. Our experiments show that the proposed method has good performance for matching two images with very different illuminations.\",\n \"Title: Progressive Coding and Illumination and View Dependent Transmission of 3-D Meshes Using R-D Optimization\\nYear: 2010\\n\\nAbstract: For transmitting complex 3D models over bandwidth-limited networks, efficient mesh coding and transmission are indispensable. The state-of-the-art 3D mesh transmission system employs wavelet-based progressive mesh coder, which converts an irregular mesh into a semi-regular mesh and directly applies the zerotree-like image coders to compress the wavelet vectors, and view-dependent transmission, which saves the transmission bandwidth through only delivering the visible portions of a mesh model. We propose methods to improve both progressive mesh cod- ing and transmission based on thorough rate-distortion (R- D) analysis. In particular, by noticing that the dependency among the wavelet coefficients generated in remeshing is not being considered in the existing approaches, we propose to introduce a preprocessing step to scale up the wavelets so that the inherent dependency of wavelets can be truly understood by the zerotree-like image compression algorithms. The weights used in the scaling process are carefully designed through thoroughly analyzing the distortions of wavelets at different refinement levels. For the transmission part, we propose to incorporate the illumination effects into the existing view-depend progressive mesh transmission system to further improve the performance. We develop a novel distortion model that considers both illumi- nation distortion and geometry distortion. Based on our proposed distortion model, given the viewing and lighting parameters, we are able to optimally allocate bits among different segments in real time. Simulation results show significant improvements in both progressive compression and transmission.\",\n \"Title: Building a Software Development Environment for Embedded Systems.\\nYear: 2010\\n\\nAbstract: This paper presents the architecture of an integrated software development toolset supporting a domain-specific framework for embedded control applications. In this particular work, emphasis is put on tool requirements concerning the graphical specification, model transformation and code generation of embedded applications built of reusable executable components that are retrieved from a component repository. Furthermore, this paper attempts to cover the important aspects of the methodology and technology needed to implement a DSL development environment, with respect to both model-driven and component based development of embedded software. The technological issues discussed come largely from the experience gained during the implementation of the prototype version of the COMDES development environment. The issues investigated and problems discovered will offer hints to other research and development efforts dealing with software development environments based on models and components.\",\n \"Title: Diversity Analysis of Analog Network Coding with Multi-User Interferences\\nYear: 2013\\n\\nAbstract: Network coding can improve the bandwidth efficiency by letting multiple users share the relay channels. However, the multi-user interferences (MUI) at the intended receiver may degrade the diversity performances. So in this work, we study several diversity strategies for the multiple-access relay channel and analyze the impact of MUI on the diversity performances. Both the variable gain relaying (VGR) and the fixed gain relaying (FGR) are considered, where the relay nodes are subject to instantaneous power constraints and long-term power constraints, respectively. We first develop a Min-Max relay selection strategy and prove that full diversity can be achieved. Next, the distributed space-time block coding (DSTBC) and the diagonal distributed space-time coding (DDSTC) are studied. For DSTBC, we show that full diversity can be achieved by FGR, but the diversity of VGR is upper bounded by min (L+1, K+1), where L and K are the number of relays and users, respectively. For single-user systems, we then develop a selective DSTBC-VGR scheme to recover the diversity loss by adaptively allocating the relay power. Finally for DDSTC, we show that both FGR and VGR can achieve full diversity, and the optimum code design criterion is to maximize the minimum product distance.\",\n \"Title: Robust Adaptive Synchronization Control for a Class of Perturbed and Delayed Neural Networks\\nYear: 2014\\n\\nAbstract: This paper is concerned with the asymptotic synchronization problem of a general neural network using the robust adaptive control technique. It is considered a class of modified Cohen---Grossberg neural networks which is supposed to undergo unknown perturbations caused by state-independent nonlinearities and bounded mixed time-varying delays on neuron amplification and activation functions. An adaptive compensation control strategy is proposed to ensure the elimination of the perturbed and delayed effects by means of adaptive estimations of unknown controller parameters. Through Lyapunov stability theory, it is shown that the proposed adaptive compensation controllers can guarantee the asymptotic synchronization of neural networks without knowing the knowledge of bounds of nonlinearities and delays. A numerical example is provided to illustrate the effectiveness of the developed techniques.\",\n \"Title: Bus Arrival Time Prediction Based on the k-Nearest Neighbor Method\\nYear: 2012\\n\\nAbstract: In this paper, a modified k-nearest neighbor (k-NN) method integrating the cluster analysis and principal component analysis is applied to bus arrival time (BAT) prediction using historical bus GPS data. The methodology of the k-NN method based on processed GPS data is presented. To validate the introduced k-NN approach, empirical analysis based on data collected from the bus No. 16 of Beijing public transport holdings, Ltd. (BPT) is performed. The results show that the k-NN method has lower prediction error than the ANN model and is more powerful in the BAT prediction.\",\n \"Title: Learning Protein Folding Energy Functions.\\nYear: 2011\\n\\nAbstract: A critical open problem in ab initio protein folding is protein energy function design, which pertains to defining the energy of protein conformations in a way that makes folding most efficient and reliable. In this paper, we address this issue as a weight optimization problem and utilize a machine learning approach, learning-to-rank, to solve this problem. We investigate the ranking-via-classification approach, especially the RankingSVM method and compare it with the state-of-the-art approach to the problem using the MINUIT optimization package. To maintain the physicality of the results, we impose non-negativity constraints on the weights. For this we develop two efficient non-negative support vector machine (NNSVM) methods, derived from L2-norm SVM and L1-norm SVMs, respectively. We demonstrate an energy function which maintains the correct ordering with respect to structure dissimilarity to the native state more often, is more efficient and reliable for learning on large protein sets, and is qualitatively superior to the current state-of-the-art energy function.\",\n \"Title: Re-Examination Of Applying Wavelet Based Progressive Image Coder For 3d Semi-Regular Mesh Compression\\nYear: 2008\\n\\nAbstract: The latest wavelet based 3D mesh coding schemes convert an irregular mesh into a semi-regular mesh and directly apply the zerotree-like image coders to compress the wavelet vectors generated in the remeshing process. The major problem of such type of approaches is that the particular properties of semi-regular meshes are not being considered in the zerotree-like image coders. In this paper, we propose an improved wavelet based 3D mesh coder. The basic idea is to introduce a preprocessing step to scale up the vector wavelets generated in remeshing so that the inherent dependency of wavelets can be truly understood by the zerotree-like image compression algorithms. The weights used in the scaling process are carefully designed through thoroughly analyzing the distortions of wavelets at different refinement levels. Experimental results show that our proposed mesh coder significantly outperforms the state-of-the-art wavelet based 3D mesh compression scheme.\",\n \"Title: Joint MMSE Transceiver Design in Non-Regenerative MIMO Relay Systems\\nYear: 2008\\n\\nAbstract: In this letter, we address the problem of transceiver design in a non-regenerative MIMO relay system, where linear processing is applied at both the relay and destination to jointly minimize the mean-squared error (MSE) of symbol estimations. Under average power constraint at the relay station, we show that the optimal relay-precoder always loads power across channel eigenvectors and then decomposes the equivalent MIMO channel into a set of parallel SISO channels. Simulation results demonstrate that our method outperforms other relaying schemes in terms of both BER and MSE.\",\n \"Title: Sparse high-dimensional fractional-norm support vector machine via DC programming.\\nYear: 2013\\n\\nAbstract: This paper considers a class of feature selecting support vector machines (SVMs) based on L\\\"q-norm regularization, where q@?(0,1). The standard SVM [Vapnik, V., 1995. The Nature of Statistical Learning Theory. Springer, NY.] minimizes the hinge loss function subject to the L\\\"2-norm penalty. Recently, L\\\"1-norm SVM (L\\\"1-SVM) [Bradley, P., Mangasarian, O., 1998. Feature selection via concave minimization and support vector machines. In: Machine Learning Proceedings of the Fifteenth International Conference (ICML98). Citeseer, pp. 82-90.] was suggested for feature selection and has gained great popularity since its introduction. L\\\"0-norm penalization would result in more powerful sparsification, but exact solution is NP-hard. This raises the question of whether fractional-norm (L\\\"q for q between 0 and 1) penalization can yield benefits over the existing L\\\"1, and approximated L\\\"0 approaches for SVMs. The major obstacle to answering this is that the resulting objective functions are non-convex. This paper addresses the difficult optimization problems of fractional-norm SVM by introducing a new algorithm based on the Difference of Convex functions (DC) programming techniques [Pham Dinh, T., Le Thi, H., 1998. A DC optimization algorithm for solving the trust-region subproblem. SIAM J. Optim. 8 (2), 476-505. Le Thi, H., Pham Dinh, T., 2008. A continuous approach for the concave cost supply problem via DC programming and DCA. Discrete Appl. Math. 156 (3), 325-338.], which efficiently solves a reweighted L\\\"1-SVM problem at each iteration. Numerical results on seven real world biomedical datasets support the effectiveness of the proposed approach compared to other commonly-used sparse SVM methods, including L\\\"1-SVM, and recent approximated L\\\"0-SVM approaches.\",\n \"Title: Recognition-driven 3D navigation in large-scale virtual environments\\nYear: 2011\\n\\nAbstract: We present a recognition-driven navigation system for large-scale 3D virtual environments. The proposed system contains three parts, virtual environment reconstruction, feature database building and recognition-based navigation. The virtual environment is reconstructed automatically with LIDAR data and aerial images. The feature database is composed of image patches with features and registered location and orientation information. The database images are taken at different distances from the scenes with various viewing angles, and these images are then partitioned into smaller patches. When a user navigates the real world with a handheld camera, the captured image is used to estimate its location and orientation. These location and orientation information are also reflected in the virtual environment. With the proposed patch approach, the recognition is robust to large occlusions and can be done in real time. Experiments show that our proposed navigation system is efficient and well synchronized with real world navigation.\",\n \"Title: Automatically extracting cancer disease characteristics from pathology reports into a Disease Knowledge Representation Model.\\nYear: 2009\\n\\nAbstract: We introduce an extensible and modifiable knowledge representation model to represent cancer disease characteristics in a comparable and consistent fashion. We describe a system, MedTAS/P which automatically instantiates the knowledge representation model from free-text pathology reports. MedTAS/P is based on an open-source framework and its components use natural language processing principles, machine learning and rules to discover and populate elements of the model. To validate the model and measure the accuracy of MedTAS/P, we developed a gold-standard corpus of manually annotated colon cancer pathology reports. MedTAS/P achieves F1-scores of 0.97-1.0 for instantiating classes in the knowledge representation model such as histologies or anatomical sites, and F1-scores of 0.82-0.93 for primary tumors or lymph nodes, which require the extractions of relations. An F1-score of 0.65 is reported for metastatic tumors, a lower score predominantly due to a very small number of instances in the training and test sets.\",\n \"Title: Anti error propagation methods for wireless uplink using network coding\\nYear: 2012\\n\\nAbstract: Wireless network coding suffers the error propagation issues that may severely degrade the diversity performance. In this work, we develop two power scaling schemes at the relay side and two detection schemes at the receiver side, respectively, to mitigate error propagation in network-coded uplink channel and thus achieve full diversity. For the soft power scaling based link adaptive relaying, we develop a virtual channel model and demonstrate that the relay power should be such to balance the signal-to-noise ratios of the source-relay channel and relay-destination channel. As for the hard power scaling based ON-OFF relaying, we first design a decision rule based on total pairwise error probability, and then simplifies it to the threshold-based relaying strategy. At the receiver side, we show that the weighted minimum distance detection with the weight being determined by the relative link quality of source-relay channel and relay-destination channel can achieve full diversity once the global channel state information is available, otherwise the maximum likelihood detection that explicitly takes into account relay decoding error should be employed to achieve full diversity.\",\n \"Title: Finite-difference modeling of the electroseismic logging in a fluid-saturated porous formation\\nYear: 2008\\n\\nAbstract: In a fluid-saturated porous medium, an electromagnetic (EM) wavefield induces an acoustic wavefield due to the electrokinetic effect. A potential geophysical application of this effect is electroseismic (ES) logging, in which the converted acoustic wavefield is received in a fluid-filled borehole to evaluate the parameters of the porous formation around the borehole. In this paper, a finite-difference scheme is proposed to model the ES logging responses to a vertical low frequency electric dipole along the borehole axis. The EM field excited by the electric dipole is calculated separately by finite-difference first, and is considered as a distributed exciting source term in a set of extended Biot's equations for the converted acoustic wavefield in the formation. This set of equations is solved by a modified finite-difference time-domain (FDTD) algorithm that allows for the calculation of dynamic permeability so that it is not restricted to low-frequency poroelastic wave problems. The perfectly matched layer (PML) technique without splitting the fields is applied to truncate the computational region. The simulated ES logging waveforms approximately agree with those obtained by the analytical method. The FDTD algorithm applies also to acoustic logging simulation in porous formations.\",\n \"Title: Map matching of mobile probes based on handover location technology\\nYear: 2010\\n\\nAbstract: With the rapid development of wireless location technologies, mobile terminals as probes have been regarded as a feasible and low cost method for real-time and wide-area city traffic information collection. If mobile probes deployed in the suburban areas, it will be a feasible supplementary way of real-time traffic information collection in China. This paper tries to investigate map matching problem of mobile probes for further traffic information extraction in the suburban areas. In this paper, handover location technology was firstly used to collect location information for a test mobile probe in field runs on a stretch of highway in the inner suburban area in Beijing. GPS data were also collected in field tests. A map matching process is proposed to find the most matched path for the test mobile probe, including two map matching algorithms, the first one of which is used for determining the matched link for each handover in a sequence of handover and the second one of which is used for determining the matched path for the whole sequence of handover. In the first map matching algorithm, frequency of handover on a candidate link, distance between the matched position and starting node of a candidate link, and geographic topological relation were combined by D-S evidence theory to determine the matched link for each handover. In the second map matching algorithm, historical matching results, real time traveling time information, drivers' route selection behavior were combined together to find the matched path for the test mobile probe. Finally, map matching performance was verified and discussed by field data collected from test runs.\",\n \"Title: Adaptive Output Feedback Control Of A Class Of Uncertain Nonlinear Systems With Unknown Time Delays\\nYear: 2012\\n\\nAbstract: This article studies the adaptive output feedback control problem of a class of uncertain nonlinear systems with unknown time delays. The systems considered are dominated by a triangular system without zero dynamics satisfying linear growth in the unmeasurable states. The novelty of this article is that a universal-type adaptive output feedback controller is presented to time-delay systems, which can globally regulate all the states of the uncertain systems without knowing the growth rate. An illustrative example is provided to show the applicability of the developed control strategy.\",\n \"Title: On analysis of wireless uplink using analog network coding with non-coherent modulations\\nYear: 2012\\n\\nAbstract: Analog network coding (ANC) has been widely used in wireless uplink to improve throughput and provide spatial diversity. However, the receiver has to estimate the channel coefficients of all users to perform coherent detection, thus the signaling overhead is sometimes formidable and may even outweigh the performance gain. To reduce the channel estimation overhead, we study non-coherent modulations in this work with emphasis on receiver design and performance analysis. Depending on channel state information, we first develop the coherent, partial coherent and non-coherent receivers based on maximum likelihood (ML) principle. As the ML non-coherent receiver has a non-tractable integral form, we further propose two suboptimum receivers depending on the relative quality of source-relay channel and relay-destination channel.We also study the pairwise error probability, and show that full diversity is still achievable at high signal-to-noise ratios using non-coherent modulations; however, the error rate decreases much slower than that of coherent systems due to the incapability to efficiently suppress multi-user interferences. Extensive simulations are also given to verify our analytical results.\",\n \"Title: Two-Way Denoise-and-Forward Relaying with Non-Coherent Differential Modulation\\nYear: 2011\\n\\nAbstract: This work focuses on a two-way denoise-and-forward relaying system using non-coherent Differential Binary Phase-Shift Keying (DBPSK) modulation. The relay denoising function and source decoders are designed using Maximum Likelihood (ML) principles. As the ML denoising function is hard to manipulate, it is approximated as a multi-user detector followed by a physical layer network coding encoder, based on which the closed-form relay decoding error is obtained. It is further shown that the ML source decoder is actually equivalent to the typical DBPSK decoder to the relay-source channel, and the exact end-to-end Bit Error Rate (BER) is derived then. A power allocation problem is also formulated to minimize the average BER at high Signal-to-Noise Ratio (SNR). It is shown that the optimal source power is inversely proportional to the square root of the channel gain of the source-relay channel, and the optimal relay power decreases with SNR.\",\n \"Title: Analysis and design of output feedback control systems in the presence of state saturation\\nYear: 2009\\n\\nAbstract: This paper studies the problems of stability analysis and dynamic output feedback controller design for continuous-time linear systems under state saturation. In this paper, both full state saturation and partial state saturation are considered. In order to solve the key problem, a new system is constructed. Firstly, a new LMI-based method is presented for estimating the domain of attraction of the origin for a closed-loop system under state saturation. Based on this method, an LMI-based algorithm is developed for constructing dynamic output-feedback controller which guarantees that the domain of attraction of the origin for the closed-loop system is as large as possible. An example is given to illustrate the efficiency of the design method.\",\n \"Title: Analysis and design of output feedback control systems in the presence of actuator saturation\\nYear: 2009\\n\\nAbstract: In this paper, a dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant (LTI) systems with actuator saturation. Firstly, the estimation of domain of attraction is given. Then, a design method to find a larger estimation of domain of attraction is presented. In the process of design, nonconvex conditions are obtained, so a cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. Two examples are given to illustrate the efficiency of the design method.\",\n \"Title: Power Allocation For Parallel Relaying System With Partial Channel State Information\\nYear: 2009\\n\\nAbstract: We introduce a novel power allocation scheme for decode-and-forward relaying system with partial channel state (CSI) information, i.e., the source knows full CSI of source-relay link but only statistical CSI of source-destination and relay-destination links. Our objective is to minimize the outage probability by jointly allocating the transmit power between the source and relays. To avoid exhaustive search, the MAOP scheme and the MMS scheme are proposed to approach the optimal allocation in the high and low signal-to-noise ratio regimes, respectively.\",\n \"Title: Analysis and controller design of discrete-time linear systems with state saturation\\nYear: 2009\\n\\nAbstract: This paper studies the problem of stability analysis and controller design for discrete-time linear time invariant (LTI) systems with state saturation. Both full state saturation and partial state saturation are considered. Firstly, a new system model is constructed for solving the key problem. Then, a new method is presented for estimating the domain of attraction of the origin for a system with state saturation. Based on this method, an LMI-based (linear matrix inequality) iterative algorithms is proposed for determining if a given ellipsoid is contractively invariant. Moreover, an LMI-based algorithm is developed for designing dynamic output-feedback controllers which guarantee that the domain of attraction of the origin for the closed-loop system is as large as possible. An example is given to illustrate the efficiency of the design method.\",\n \"Title: A Nonlinear Pairwise Swapping Dynamics to Model the Selfish Rerouting Evolutionary Game\\nYear: 2013\\n\\nAbstract: Abstract In this paper, a nonlinear revision protocol is proposed and embedded into the traffic evolution equation of the classical proportional-switch adjustment process (PAP), developing the present nonlinear pairwise swapping dynamics (NPSD) to describe the selfish rerouting evolutionary game. It is demonstrated that i) NPSD and PAP require the same amount of network information acquisition in the route-swaps, ii) NPSD is able to prevent the over-swapping deficiency under a plausible behavior description; iii) NPSD can maintain the solution invariance, which makes the trial and error process to identify a feasible step-length in a NPSD-based swapping algorithm is unnecessary, and iv) NPSD is a rational behavior swapping process and the continuous-time NPSD is globally convergent. Using the day-to-day NPSD, a numerical example is conducted to explore the effects of the reaction sensitivity on traffic evolution and characterize the convergence of discrete-time NPSD.\",\n \"Title: Mitigating Error Propagation for Wireless Network Coding\\nYear: 2012\\n\\nAbstract: Network coding has been widely used in wireless uplink to improve spectral efficiency. However, the relay decoding error may propagate to the intended receiver and thus severely degrade the diversity performance. So in this work, we develop two power scaling schemes at the relay side and two detection schemes at the receiver side, respectively, to mitigate error propagation and thus achieve full diversity for the two-user multiple access relay network. For the soft power scaling based link adaptive relaying, we develop a virtual source-relay-destination channel model and demonstrate that the relay power should be such to balance the signal-to-noise ratios of the source-relay channel and relay-destination channel. As for the hard power scaling based ON-OFF relaying, we first design a decision rule based on total pairwise error probability, and then simplify it to the threshold-based relaying strategy. At the receiver side, we show that the weighted minimum distance detection with the weight being determined by the relative link quality of source-relay channel and relay-destination channel can achieve full diversity once the global channel state information is available, otherwise the maximum likelihood detection should be employed to achieve full diversity when the receiver only knows the local channel state information.\",\n \"Title: Study on berth planning problem in a container seaport: Using an integrated programming approach\\nYear: 2012\\n\\nAbstract: This paper provides an integrated solution for two common processes in a container seaport: namely, the Berth Allocation Process (BAP) and the Crane Scheduling Process (QCSP). These are formulated through a Bi-Level Programming (BLP) approach, which is used to characterize the highly interrelated relationships between the two processes and simultaneously, identify an integrated solution for both. The upper-level problem (BAP) is termed 'NP-hard' as its computational complexity increases exponentially with the number of incoming ships for mooring, while the lower-level problem (QCSP) is a mixed-integer linear program. A revised genetic algorithm and a branch-and-bound method (B&B) are then applied for the solutions of upper and lower level problems, respectively.\",\n \"Title: GPS-aided recognition-based user tracking system with augmented reality in extreme large-scale areas\\nYear: 2011\\n\\nAbstract: We present a recognition-based user tracking and augmented reality system that works in extreme large scale areas. The system will provide a user who captures an image of a building facade with precise location of the building and augmented information about the building. While GPS cannot provide information about camera poses, it is needed to aid reducing the searching ranges in image database. A patch-retrieval method is used for efficient computations and real-time camera pose recovery. With the patch matching as the prior information, the whole image matching can be done through propagations in an efficient way so that a more stable camera pose can be generated. Augmented information such as building names and locations are then delivered to the user. The proposed system mainly contains two parts, offline database building and online user tracking. The database is composed of images for different locations of interests. The locations are clustered into groups according to their UTM coordinates. An overlapped clustering method is used to cluster these locations in order to restrict the retrieval range and avoid ping pong effects. For each cluster, a vocabulary tree is built for searching the most similar view. On the tracking part, the rough location of the user is obtained from the GPS and the exact location and camera pose are calculated by querying patches of the captured image. The patch property makes the tracking robust to occlusions and dynamics in the scenes. Moreover, due to the overlapped clusters, the system simulates the \\\"soft handoff\\\" feature and avoid frequent swaps in memory resource. Experiments show that the proposed tracking and augmented reality system is efficient and robust in many cases.\",\n \"Title: Component-based analysis of embedded control applications\\nYear: 2012\\n\\nAbstract: The widespread use of embedded systems requires the creation of industrial software technology that will make it possible to engineer systems being correct by construction. That can be achieved through the use of validated (trusted) components, verification of design models, and automatic configuration of applications from validated design models and trusted components. This design philosophy has been instrumental for developing COMDES--a component-based framework for distributed embedded control systems. A COMDES application is conceived as a network of embedded actors that are configured from instances of reusable, executable components--function blocks (FBs). System actors operate in accordance with a timed multitasking model of computation, whereby I/O signals are exchanged with the controlled plant at precisely specified time instants, resulting in the elimination of I/O jitter. The paper presents an analysis technique that can be used to validate COMDES design models in SIMULINK. It is based on a transformation of the COMDES design model into a SIMULINK analysis model, which preserves the functional and timing behaviour of the application. This technique has been employed to develop a feasible (light-weight) analysis method based on runtime observers. The latter are conceived as special-purpose actors running in parallel with the application actors, while checking system properties specified in Linear Temporal Logic. Observers are configured from reusable FBs that can be exported to SIMULINK in the same way as application components, making it possible to analyze system properties via simulation. The discussion is illustrated with an industrial case study--a Medical Ventilator Control System, which has been used to validate the developed design and analysis methods.\",\n \"Title: Computationally efficient retrieval-based tracking system and augmented reality for large-scale areas\\nYear: 2011\\n\\nAbstract: We present a retrieval-based tracking system that requires less computational time and cost. The system tracks a user's location through a small portion of an image captured by the camera, and then refines the camera pose by propagating matchings to the whole image. Augmented information such as building names and locations will be delivered to the user. The progressive way to process image data not only can provide the user with location information at real-time speed, but more importantly, it reduces the feature matching time by limiting the searching ranges. The proposed system contains two parts, offline database building and online user tracking. The database is composed of image patches with features and location information. The images are captured at different locations of interests from different viewing angles and distances, and then these images are partitioned into smaller patches. The location of a user can be calculated by querying one or more patches of the captured image. Moreover, the system is capable to handle large occlusions in images due to the patch approach. Experiments show that the proposed tracking system is efficient and robust in many different environments.\",\n \"Title: Component-Based Design of Software for Embedded Control Systems: The Medical Ventilator Case Study\\nYear: 2009\\n\\nAbstract: COMDES-II is a component-based framework for distributed control systems featuring open architecture and predictable operation under hard real-time constraints. It has been experimentally validated in a number of case studies, including the Medical Ventilator Case Study discussed in the paper. The latter presents COMDES-II design models used to re-engineer the control system of an existing Medical Ventilator machine, and the resulting software implementation. The accumulated experience has helped reveal areas of possible improvement, and they have been taken into consideration while developing the latest version of the framework - COMDES-III.\",\n \"Title: Complex Learning System for Behavior Factor based Data Analysis.\\nYear: 2013\\n\\nAbstract: In this paper, we propose a complex learning system for data analysis that is based on behavior factor. This system combines features of both order based systems and order based data analysis framework. This system uses an appropriate behavior factor acquisition process, which is the weakest task in the current order and behavior factor based systems. As several research works have shown that data analysis is rather driven by domain behavior factor than by data, we have identified and analyzed the characters that distinguish behavior factor and orders from data for better determining the most components of the proposed system. This paper describes an approach that advocates the use of behavior factor order-based systems techniques for data analysis systems. In particular, we aim to make domain behavior factor explicit and separate from the system where will be used for data analysis. For representing domain behavior factor, we investigated a uniform and unified order representation form based on the creation of the environment component that stored information especially for the management of order and its quality. © 2013 ACADEMY PUBLISHER.\",\n \"Title: Linear Relaying Scheme for MIMO Relay System With QoS Requirements\\nYear: 2008\\n\\nAbstract: In this letter, we address the problem of fulfilling quality-of-service (QoS) requirements in a multiple-input multiple-output (MIMO) relay system, where a set of target signal-to-noise ratios (SNRs) should be attained on different substreams. By solving a two-step optimization problem, we obtain a power-efficient relaying scheme that can make the SNR requirements asymptotically fulfilled. A simple relay selection method is also proposed such that the relay-power consumption can be largely reduced when there is a large number of relays.\",\n \"Title: A qualitative model of cross-lane inhomogeneities in traffic flow\\nYear: 2004\\n\\nAbstract: The dilemma of traditionally quantitative methods in application to complex systems leads more and more researchers to emphasize the qualitative methods that can tackle the qualitative knowledge. Based on the concepts and ideas of qualitative reasoning, a preliminary qualitative method for modeling the traffic flow is proposed in this paper. Following new concepts, such as the homogenous measure index, which can be treated as an entropy to judge the homogeneity of traffic flow, a set of linear parameters-varying difference equations is used to describe the process of qualitative state transitions of the traffic flow. The procedures as well as the rationality of qualitative modeling for the traffic flow are illustrated by the data obtained from an actual traffic system-the Beijing Third Ring Road. Comparing the simulation results with actual data, it is proven that the results obtained by the proposed qualitative model coincide with the actual situation and the qualitative model can basically depict the nonhomogenous state transitions of traffic flow.\",\n \"Title: Aircraft recognition in infrared image using wavelet moment invariants\\nYear: 2009\\n\\nAbstract: Automatic Target Recognition (ATR) of infrared object has been taking a great interest to the researchers in recent years. ATR requires invariance of high cognition accuracy in translation, scaling and orientation, but classification of two-dimensional (2D) shapes despite of their position, size and orientation in infrared image remains a difficult problem. In this paper, a feature extraction method is proposed using Wavelet Moment Invariants (WMI). The very similar objects can be classified correctly by virtue of the wavelet moment with its multi-resolution properties. Compared with some other geometry moments, the classification rate and the recognition efficiency are improved with wavelet moments. As different wavelet basis will have different impacts to wavelet moment, it affects the efficiency of classification. Some important properties such as orthonomality, supported length and vanishing moments which affect the performance of wavelet moment are discussed in this paper. Through experimental analysis, a conclusion is obtained that symmetry, compactly supported wavelet has more high-performance, and using wavelet function with proper vanishing moments could effectively improve the efficiency of classification.\",\n \"Title: Investigation on traffic flow competition between main road and on-ramp on urban freeway\\nYear: 2012\\n\\nAbstract: Bottlenecks at highway or urban freeway are one of origins of traffic congestion. Based on empirical investigation on traffic data collected from Beijing urban freeway, we find that when traffic is dense, upstream flow and ramp flow are correlated significantly. Competitions between the two flows at vicinities of several on-ramps during a morning peak are studied. Based on these empirical observations, a flow competition model as an extension of CTM (cell transmission model) is developed. The proposed model focuses on reproducing correlated upstream flow and ramp flow in dense traffic. Both empirical data and simulation results point out that several traffic phenomena, such as capacity drop and spontaneous traffic breakdown, can be explained as results of such a competition.\",\n \"Title: Design and Implementation of bus crew scheduling system using integrated casebased and rule-based reasoning\\nYear: 2012\\n\\nAbstract: The bus crew scheduling problem (BCSP) is to assign drivers and conductors to daily crew duties that cover a set of schedules for buses of a public bus company during a period of time, e.g., a week. By combining case-based reasoning (CBR) and rule-based reasoning (RBR), this paper introduces the design and implementation of a bus crew scheduling system (BCSS). The current system works like this. Firstly, an inference mechanism integrating CBR and RBR is designed to obtain near-optimal solutions. Secondly, based on these nearoptimal solutions, a genetic algorithm is developed to produce better solutions. The practical applications show that the system is effective. © 2012 IEEE.\",\n \"Title: ITS planning methodology for Chinese cities and its evaluation model\\nYear: 2006\\n\\nAbstract: ITS Planning Methodology (IPM) is significant to guide the ITS Research &Development (R&D) strategically and systematically. This paper develops a general IPM and the ITS strategic objectives for Chinese cities, which creates a methodological framework to plan the urban ITS. During ITS planning, the ITS evaluation is a key component to make decisions. Based on the IPM and its objectives, for making up the deficiency of conventional evaluation methods, an ITS evaluation model by artificial neural network is built, and its feasibility has been proved by case study. The result shown by the planning and simulation is satisfied. It is practical and convenient to apply this model in the factual ITS planning. © 2006 IEEE.\",\n \"Title: Study on Bus Route Evaluation System in Beijing Based on AHP\\nYear: 2007\\n\\nAbstract: Bus route evaluation (BRE) of the public transit system in Beijing is requisite decision to regulate existing bus routes and reallocate transit resources for sustain operation. Since there wasn't a systematic BRE system for Beijing, firstly, this paper develops comprehensive BRE standards according to the status quo of Beijing's transit system, which includes 3 categories, 20 criterions in total. Secondly, based on method of Analytical Hierarchy Process (AHP), a BRE model is built, which integrates quantitative and qualitative attributes of routes. Finally, in terms of passenger flow data investigated, a case study of BRE among No. 7, No. 15, and No. 334 bus routes is carried out. It shows that the evaluation result by this BRE system is consistent with the actual condition of the transit system in Beijing. It is practicability and maneuverability to apply this model to regulate and optimize bus routes in Beijing.\",\n \"Title: Empirical Investigations on Traffic Phase Transitions at Beijing Ring Road\\nYear: 2007\\n\\nAbstract: In this paper, traffic features of urban ring road are investigated based on empirical data of Beijing 2\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">nd</sup>\\n Ring Road. According to the concept of \\\"synchronized flow\\\" as well as the stability and synchronization among lanes around critical density, four traffic phases are identified: free flow, high-speed synchronized flow, low-speed synchronized flow and traffic jam. Moreover, spatio-temporal features of traffic flow based on these four phases are investigated empirically.\",\n \"Title: Empirical Investigation on Phase Diagram at Urban Freeway with On-ramp\\nYear: 2008\\n\\nAbstract: Bottlenecks at highway or urban freeway are one of origins of traffic congestion. Based on empirical investigation on field data of Beijing urban freeway, schematic phase diagram at on-ramp vicinity is developed and detailed phase transition processes are investigated. There are five phases in the phase diagram of on-ramp vicinity in connection with on-ramp flow and upstream flow, among which are two phases only observed in urban freeway traffic. It's also found that the empirical phase diagram developed in this paper is different from previous theoretical phase diagram of highway traffic. The boundaries of each phase are influenced by traffic demand at locations, such that empirical phase diagrams are vary in quantities at different locations. Moreover, according to investigation on empirical phase transition process, coherent moving flow, as a new phase observed in urban freeway flow in our previous work, is confirmed.\",\n \"Title: Phase Transition of Urban Freeway Traffic Flow\\nYear: 2008\\n\\nAbstract: At present, research on traffic flow theory has mainly focused on highway traffic, which is significantly different from urban freeway traffic. Traffic science is an \\\"empirical science\\\", and as such is it is based on empirical urban freeway traffic flow data. In this study, first four steady phases are identified in the flow-density plane of traffic flow: free flow, coherent-moving flow, synchronized flow and jam. Then, three modes of phase transition, i.e. spontaneous transition, propagating transition (PT) and induced transition (IT) are analyzed, and the judgment conditions as well as computable methods of PT and IT are discussed in detail. Finally, based on actual data of the Beijing urban freeway, an empirical analysis of phase transition from coherent-moving flow to synchronized flow, which is the process of \\\"smooth traffic\\\" transferring to \\\"congested traffic\\\", is presented to validate the concepts and methods proposed in this paper.\",\n \"Title: Two-Way Network-Coded Relaying With Delay Constraint\\nYear: 2015\\n\\nAbstract: Random channel fading may cause serious channel outage, and automatic repeat-request protocol has been widely used to mitigate packet loss by retransmitting the packet when the receiver fails to decode that packet. To restrict the transmission delay, a single packet might be retransmitted up to a limited number of times. For wireless two-way relay channels, the packet could be retransmitted by the original source node or the relay nodes, and the delay constraint might be imposed in a per-hop manner or end-to-end manner. For single-relay networks, we study the throughput of several relaying strategies including pure relaying and network-coded relaying subject to the delay constraint. We demonstrate that the binary xor-based network coding can greatly improve the system throughput, but the throughput gain is upper bounded. We also develop a near-optimum power allocation scheme to maximize the system throughput. For multirelay networks, we show that using digital network coding alone may cause some throughput loss when the frame length is much smaller than the number of relays, and we develop a hybrid network coding scheme to recover such throughput loss.\",\n \"Title: Robust Image Matching With Line Context\\nYear: 2013\\n\\nAbstract: We present a novel type of feature that is robust to challenging images that are mainly due to large illumination variations. The keypoints are detected so that they are repeatable with consistent scales in images of different illuminations, and the descriptors are formed by the context of neighboring line segments. Similar to many popular local features, the proposed feature is robust to occlusions, viewpoint changes and image clutters. Differently, while most state-of-the-art features can only handle small or monotonic illumination changes, our proposed feature is capable to match images with large and non-monotonic illumination variations. Through extensive experiments, the proposed feature is demonstrated to be robust and efficient in matching such challenging images.\",\n \"Title: Outage probability optimization with equal and unequal transmission rates under energy harvesting constraints\\nYear: 2013\\n\\nAbstract: In this paper, we study the power scheduling problem to optimize the outage probability with both equal and unequal transmission rates under energy harvesting constraints. In particular, we first model the average outage probability minimization problem over finite horizon, and then reformulate the problem by minimizing its upper bound, which converts the non-convex problem to a more efficient convex optimization problem. Next, we show the optimal power scheduling solution is related to the global minimum of an energy-and-time function which is defined as arithmetic average of harvested energy from current time slot to the arbitrary time slot in the future before the end of transmission. Based on such properties, we propose a Min-Average strategy which presents the optimal performance in upper bound of outage probability for equal and non-equal transmission rates. Simulation results show that, our power scheduling scheme achieves better outage performance compared to other alternative strategies, e.g, best-effort, fixed-saving and random saving strategies.\",\n \"Title: A Heterogeneous Multi-Core Architecture with a Hardware Kernel for Control Systems.\\nYear: 2012\\n\\nAbstract: Rapid industrialisation has resulted in a demand for improved embedded control systems with features such as predictability, high processing performance and low power consumption. Software kernel implementation on a single processor is becoming more difficult to satisfy those constraints. This paper presents a multi-core architecture incorporating a hardware kernel on FPGAs, intended for high performance applications in control engineering domain. First, the hardware kernel is investigated on the basis of a component-based real-time kernel HARTEX (Hard Real-Time Executive for Control Systems). Second, a heterogeneous multi-core architecture is investigated, focusing on its performance in relation to hard real-time constraints and predictable behavior. Third, the hardware implementation of HARTEX is designated to support the heterogeneous multi-core architecture. This hardware kernel has several advantages over a counterpart kernel implemented in software: higher-speed processing capability, parallel computation, and separation between the kernel itself and the applications being run. A microbenchmark has been used to compare the hardware kernel with the software kernel, and compare the kernel on the multi-core platform with the kernel on the single-core platform.\",\n \"Title: Calibration of accelerometer with multicomponent inputs\\nYear: 2014\\n\\nAbstract: For reducing the inconsistency of sensors' characteristics in laboratory and working conditions, calibration of an accelerometer with multicomponent inputs is introduced. After a review of current equipments which are capable of producing combined accelerations, we introduced a different apparatus which can offer simultaneous harmonic and constant linear accelerations. It consists of a vibration exciter mounted on a centrifuge. With reference to the output model of the machine, we present a calibration method based on the vibration rectification error of accelerometer. The method is a multi-orientation test scheme with four different configurations and numerically validated in this paper. More investigations are needed to improve the calibration of accelerometer with multicomponent accelerations.\",\n \"Title: Accelerometer transverse sensitivity testing with double turntable centrifuge\\nYear: 2014\\n\\nAbstract: An approach suitable for calibrating the transverse sensitivity of accelerometer at low-frequency is presented in this work. The method proposed here employs the double turntable centrifuge as the apparatus to provide standard reference accelerations. Numerical simulation and experimental investigation are done to validate the method. Testing results of a single-axis inertial accelerometer are consistent with the simulation. Typical `8' figure of the accelerometer transverse sensitivity is obtained. Both the simulation and experiment results show that the testing of the accelerometer transverse sensitivity of with the double turntable centrifuge is practicable..\",\n \"Title: Non-fragile fuzzy dissipative static output feedback control for Markovian jump systems subject to actuator saturation.\\nYear: 2016\\n\\nAbstract: In this paper, the problem of non-fragile fuzzy dissipative static output feedback control for Markovian jump systems subject to actuator saturation is considered. Based on Lyapunov theory and reciprocally convex combination lemma, sufficient conditions are obtained to ensure the closed-loop system to be stochastically stable and dissipative. Then, the non-fragile fuzzy static output feedback controller can be obtained by solving the LMIs. And the estimation of the largest domain of attraction for the system is solved as a LMI optimization problem. Finally, some numerical examples are provided to show the effectiveness of the proposed method.\",\n \"Title: A novel wavelet-SVM short-time passenger flow prediction in Beijing subway system\\nYear: 2015\\n\\nAbstract: In order to effectively manage the use of existing infrastructures and prevent the emergency caused by the large gathered crowd, the short-term passenger flow forecasting technology becomes more and more significant in the field of intelligent transportation system. However, there are few studies discussing how to predict different kinds of passenger flows in the subway system. In this paper, a novel hybrid model Wavelet-SVM is proposed, and it combines the complementary advantages of Wavelet and SVM models, and meanwhile overcomes their shortcomings respectively. The Wavelet-SVM forecasting approach consists of three important stages. The first stage decomposes the passenger flow data into different high frequency and low frequency series by wavelet. During the prediction stage, the SVM method is applied to learn and predict the corresponding high frequency and low frequency series. In the last stage, the diverse predicted sequences are reconstructed by wavelet. The experimental results show that the approach not only has the best forecasting performance compared with the state-of-the-art techniques but also appears to be the most promising and robust based on the historical passenger flow data in Beijing subway system and several standard evaluation measures.\",\n \"Title: Design and implementation of wireless monitoring network for temperature-humidity measurement.\\nYear: 2016\\n\\nAbstract: In order to overcome the shortcomings of existing wireless temperature-humidity monitoring systems, such as high-energy consumption, poor man–machine interaction, differential interference and no reverse real-time control etc., a novel real-time temperature-humidity monitoring system based on short distance wireless microwave communication is designed. In addition, some intelligent algorithms are briefly introduced in wireless communication for frequency assignment, improving energy efficiency and other resource allocation problems. This system uses the chip STC89C52 as the control chip, chip SHT11 as the data acquisition module, chip nRF905 as wireless transceiver module and chip MAX232 as the serial interface between the upper and the lower computer. The system requirements, system design, correlative hardware circuits, control flow chart and software design are depicted in details. This system can realize data acquisition, processing, transmission, control and display of temperature and humidity information. The system functions verification and performance test results show that this system has strong interference, low energy consumption and high precision. This system has great valuable, which has been applied in industrial and agricultural fields, such as greenhouse cultivation and laboratory storage.\",\n \"Title: A Security-Critical Task Management Method for Distributed Real-Time Systems.\\nYear: 2015\\n\\nAbstract: Security has become an important constraint in distributed real-time task system. For this paper, we give a security-critical distributed real-time task management model, then present a scheme for security-critical task management in the distributed real-time system, finally we propose an algorithm to solve the management problem in the distributed real-time system. We propose a security-critical distributed real-time task management model, and formulate the security-critical distributed real-time system task management issue into a shortest path problem. We solve the shortest path problem by using the improved Dijkstra algorithm. In addition, we validate the efficiency of the algorithm by simulation experiments.\",\n \"Title: Finite-time dissipative control for singular T-S fuzzy Markovian jump systems under actuator saturation with partly unknown transition rates.\\nYear: 2016\\n\\nAbstract: In this paper, we consider the problem of the static output feedback control for singular T-S fuzzy Markovian jump system with considering the influence of actuator saturation and partly unknown transition probabilities. Sufficient conditions are obtained to guarantee that the closed-loop is not only finite time bounded but also dissipative. The controller gain and the estimation of the domain of attraction can be solved by solving the linear matrix inequalities based optimization problem. Finally, numerical examples are illustrated for the effectiveness of the proposed method.\",\n \"Title: A self-regulation traffic-condition-based route guidance strategy with realistic considerations: Overlapping routes, stochastic traffic, and signalized intersections\\nYear: 2016\\n\\nAbstract: Variable message signs that provide various types of route guidance information have been widely deployed in large cities. To release proper information only using easily collected data, a simple traffic-condition-based (TCB) route guidance strategy was recently proposed. The strategy works based on the estimation of free-flow and congested traffic conditions and is capable of approximating user optimal equilibrium stably. Due to little consideration of the complexity of urban road networks, the TCB strategy is still away from field applications in urban areas. To further push the strategy toward field tests, this article improves the TCB strategy in the following aspects: supplementing the strategy with a self-regulation ability by considering existing traffic conditions; decomposing link capacity to solve the problem of overlapping routes by comparing link capacity on alternative routes; coping with stochastic traffic; and the impact of signalized intersections by utilizing aggregated data. A scenario for an urban road network in Beijing, China, is simulated to test the improved strategy, and the simulation results clearly indicate the effectiveness of the proposed improvements. The improvements extend the TCB strategy on moderately complicated urban road networks, and still have the advantages of simple diversion rules, easily obtained input data, and stable and effective diversion processes.\",\n \"Title: Mapping to Cells: A Simple Method to Extract Traffic Dynamics from Probe Vehicle Data.\\nYear: 2017\\n\\nAbstract: In the era of big data, mining data instead of collecting data are a new challenge for researchers and engineers. In the field of transportation, extracting traffic dynamics from widely existing probe vehicle data is meaningful both in theory and practice. Therefore, this article proposes a simple mapping-to-cells method to construct a spatiotemporal traffic diagram for a freeway network. The method partitions a network region into small square cells and represents a real network inside the region by using the cells. After determining the traffic flow direction pertaining to each cell, the spatiotemporal traffic diagram colored according to traffic speed can be well constructed. By taking the urban freeway in Beijing, China, as a case study, the mapping-to-cells method is validated, and the advantages of the method are demonstrated. The method is simple because it is completely based on the data themselves and without the aid of any additional tool such as Geographic Information System software or a digital map. The method is efficient because it is based on discrete space-space and time-space homogeneous cells that allow us to match the probe data through basic operations of arithmetic. The method helps us understand more about traffic congestion from the probe data, and then aids in carrying out various transportation researches and applications.\",\n \"Title: Distributed Optimization of Hierarchical Small Cell Networks: A GNEP Framework.\\nYear: 2017\\n\\nAbstract: Deployment of small cell base stations (SBSs) overlaying the coverage area of a macrocell BS (MBS) results in a two-tier hierarchical small cell network. Cross-tier and inter-tier interference not only jeopardize primary macrocell communication but also limit the spectral efficiency of small cell communication. This paper focuses on distributed interference management for downlink small cell networks. We address the optimization of transmit strategies from both the game theoretical and the network utility maximization (NUM) perspectives and show that they can be unified in a generalized Nash equilibrium problem (GNEP) framework. Specifically, the small cell network design is first formulated as a GNEP, where the SBSs and MBS compete for the spectral resources by maximizing their own rates while satisfying global quality of service (QoS) constraints. We analyze the GNEP via variational inequality theory and propose distributed algorithms, which only require the broadcasting of some pricing information, to achieve a generalized Nash equilibrium (GNE). Then, we also consider a nonconvex NUM problem that aims to maximize the sum rate of all BSs subject to global QoS constraints. We establish the connection between the NUM problem and a penalized GNEP and show that its stationary solution can be obtained via a fixed point iteration of the GNE. We propose GNEP-based distributed algorithms that achieve a stationary solution of the NUM problem at the expense of additional signaling overhead and complexity. The convergence of the proposed algorithms is proved and guaranteed for properly chosen algorithm parameters. The proposed GNEP framework can scale from a QoS constrained game to an NUM design for small cell networks by trading off signaling overhead and complexity.\",\n \"Title: Graphical Human–Machine Interactive Approach for Integrated Bus Transit Scheduling: Lessons Gained From a Large Bus Company\\nYear: 2017\\n\\nAbstract: This paper describes an integrated human–machine interactive bus transit scheduling system developed for the Beijing Public Transport Holdings (Group) Company, Ltd. (BPTG), one of the largest bus companies in the world. The system, which is based on a highly informative deficit function graphical optimization technique, allows schedulers to select computer-generated improvements or interject their own practical considerations. The initial implementation of the new system in two subcompanies of BPTG demonstrates its effectiveness and efficiency with many good features, such as improved integration and coordination of scheduling vehicles and crews, reduced vehicle fleet size, and reduced number of crew duties.\",\n \"Title: Erasing Lane Changes From Roads: A Design of Future Road Intersections.\\nYear: 2018\\n\\nAbstract: Imagine in the future that autonomous vehicles coordinated and guided by signal-free autonomous intersections are able to pass through the intersections immediately after the vehicles in the conflicting direction leave. Meanwhile, with the coordination of the autonomous intersections, autonomous vehicles on any approaching lane are able to turn onto any downstream lane, expecting that driving in s...\",\n \"Title: Facial semantic descriptors based on information granules.\\nYear: 2019\\n\\nAbstract: In this paper, we investigate a granular data description for facial components in which a characterization of facial components is presented by a collection of information granules. Firstly, the facial landmark detector is utilized to extract facial components automatically. Secondly, semantic concepts are formed by involving various mechanisms of fuzzy clustering based on these detected landmarks. A collection of numeric prototypes can be sought as a blueprint of the descriptors. Consequently, the information granules are being formed around the prototypes that are engaged by the fundamental ideas of Granular Computing, especially the principle of justifiable granularity. Multiple experiments on Multi-PIE facial database illustrate the proposed facial semantic descriptors based on information granules not only can characterize the key semantics of facial components of data, but also can improve the semantic classification performance in comparison with human perception.\",\n \"Title: Analysis and Prediction of Regional Mobility Patterns of Bus Travellers Using Smart Card Data and Points of Interest Data\\nYear: 2019\\n\\nAbstract: Mobility patterns at region level can provide more macroscopic and intuitive knowledge on how people gather in or depart from the region. However, the analysis and prediction of regional mobility patterns have yet to be effectively addressed. In light of this, using smart card data (SCD) and points of interest (POI) data, a multi-step methodology which integrates the inner-restricted fuzzy C-means clustering, nonnegative tensor factorization and artificial neural network are proposed and implemented in this paper. It overcomes the difficulties in region division, pattern extraction, and prediction. The bus SCD and POI data in Beijing city are utilized for proving the usefulness of the methodology. The regional mobility patterns of bus travellers in Beijing city are extracted from the third-order tensors involving 1110 regions, 34 time slots, and 7 days of the week. The analyzed results show that the proposed methodology has a good performance on predicting the regional mobility patterns based on the regional properties. Furthermore, by considering both of the regional boarding and alighting patterns, the predictions of the regional aggregation pattern can also be achieved. These research achievements can not only provide a deep insight on the human mobility patterns at region level, but also support the evidence-based and forward-looking urban planning and intelligent transportation management.\",\n \"Title: Vehicle sensor data-based analysis on the driving style differences between operating indoor simulator and on-road instrumented vehicle\\nYear: 2019\\n\\nAbstract: Indoor simulator and on-road instrumented vehicle are the most popular ways to analyze driving behaviors by using collected Vehicle Sensor Data (VSD). However, for a same driver, the driving performance could be different in the real world and in the simulated world. Even though many studies have been conducted to discover the differences of driving behaviors in these two circumstances, little research has focused on analyzing the differences in driving style, which can provide more integrated knowledge of a driver from the natural structure, stimulus–response mechanism, of driving behaviors. Therefore, in this paper, the driving styles in both the real world and the simulated world are extracted by implementing the nonnegative matrix factorization method on the collected VSD data. Through this analysis, the driving style differences can be quantitatively described and discussed in detail. It is found that the drivers tend to be more unstable and sometimes aggressive when driving the simulator and the deviation in the perception of temporal gap in two circumstances is also discovered. The research findings are particularly valuable to calibrate the driving simulator and construct more reliable driving behavior models.\",\n \"Title: Probability Distribution of Represented Sources in Conversations of Adults and Children\\nYear: 2020\\n\\nAbstract: Based upon a taxonomy of represented sources, this paper investigates the quantitative features of two groups - one comprised of adults and the other of seven-year-old children - that employ a variety of sources in everyday representation. Results indicate that: 1) the overall probability distributions of represented sources used by both groups fit well to the modified right truncated Zipf-Alekseev distribution; 2) the R-2 value of the adult group is lower than that of the child group, largely due to the prevalence of non-present non-specified human references by the adults; 3) the values of fitting parameters a and n differ significantly between the two groups; 4) while representing from sources is an extralinguistic phenomenon, it nevertheless reflects the similar quality of language (i.e. a human-driven complex adaptive system), and it also offers a better understanding of the quantitative features of this phenomenon. In summary, this study presents the results of several preliminary attempts to study a specific type of extralinguistic phenomenon from a quantitative perspective.\",\n \"Title: Finite-Time Filtering for Discrete-Time Singular Markovian Jump Systems with Time Delay and Input Saturation\\nYear: 2019\\n\\nAbstract: The paper is discussed with the problem of finite-time H-infinity filtering for discrete-time singular Markovian jump systems (SMJSs). The systems under consideration consist of time-varying delay, actuator saturation and partly unknown transition probabilities. We pay attention to the design of a H-infinity filtering which ensures the filtering error systems to be singular stochastic finite-time boundedness. By employing an adequate stochastic Lyapunov functional together with a class of linear matrix inequalities (LMIs), a sufficient condition is firstly established, which guarantees the systems to achieve our goal and satisfy a prescribed H-infinity attenuation level in the given finite-time interval. Considering the above conditions, a distinct presentation for the requested H-infinity filter is given. Finally, two numerical examples add to a dynamical Leontief model of economic systems are presented to illustrate the validity of the developed theoretical results.\",\n \"Title: Semantics characterization for eye shapes based on directional triangle-area curve clustering\\nYear: 2019\\n\\nAbstract: In this paper, we present a novel approach to address the problem of eye shape characterization via curve representation. Firstly, a directional triangle-area curve representation method (DTAR) is presented for this aim. Equipped with DTAR, the shape similarities between two eyes can be measured by the similarities between two corresponding DTAR curves. Secondly, in order to exploit the underlying information of eye shapes, a curve clustering algorithm is utilized to automatically discover a set of eye shape prototypes. Consequently, a semantics extraction method for eye shapes is proposed in terms of seven reference eye shapes. Finally, in order to validate the consistency of the clustering results and the extracted semantics, extensive experiments on AR and BU4DFE databases are designed and conducted, and all the results demonstrate the effectiveness of the proposed DTAR curve representation and the semantics extraction method.\",\n \"Title: Dissipative control for singular T-S fuzzy Markov jump systems under quantized feedback\\nYear: 2019\\n\\nAbstract: In this paper, we investigate the design problem of the feedback controller for singular T-S fuzzy Markov jump system considering the influence of uncertainties, time-delay, and signal quantization. A sufficient condition is obtained to guarantee the closed-loop system not only stochastically admissible but also dissipative. Subsequently, the dissipative quantized controller is designed by solving the linear matrix inequalities (LMIs), which takes into consideration the nonrepresentational energy, storage function, and supply rate for the disturbance weaken and gives a unified framework that can include the existing results for passivity and H-infinity controllers as special cases for the considered system. Finally, numerical examples have illustrated the effectiveness of the proposed method.\",\n \"Title: Generative character inpainting guided by structural information\\nYear: 2021\\n\\nAbstract: Character inpainting is an attractive and challenging task, especially for Chinese calligraphy characters with complex structures and styles. The diversity of Chinese calligraphy styles has created its unique artistic beauty, but specific style features will lead to obvious differences in style and stroke details while recovering. Most current methods are restricted to recover specific characters already present in the training set and retrain the model when recovering characters of new styles. Moreover, these methods are based on edge recovery, which requires the location of the masked area. In this paper, we propose a novel structure-guided generative framework guided by prototype character, which can not only adapt to multiple style fonts but also overall recover glyph structure and strokes without masked information by inferring the style representation. In this case, our method can recover new style characters, which is the first attempt for character inpainting without parameter retraining. Experimental results demonstrate that our method has generalizability and superiority in most application scenarios, compared with several state-of-the-art character inpainting methods.\",\n \"Title: A Novel Multi-channel Random Competitive MAC Protocol Based on Channel Load Prediction Mechanism for ATNs\\nYear: 2021\\n\\nAbstract: For the dramatic decrease of network performance under heavy traffic load in existing medium access control (MAC) protocols in airborne tactical networks, a multi-channel random competitive MAC protocol based on a novel statistical prediction-based access decision mechanism is proposed in this paper. The MAC protocol mainly consists of the channel load prediction mechanism, the packet access decis...\",\n \"Title: Intelligent Smart Marine Autonomous Surface Ship Decision System Based on Improved PPO Algorithm\\nYear: 2022\\n\\nAbstract: With the development of artificial intelligence technology, the behavior decision-making of an intelligent smart marine autonomous surface ship (SMASS) has become particularly important. This research proposed local path planning and a behavior decision-making approach based on improved Proximal Policy Optimization (PPO), which could drive an unmanned SMASS to the target without requiring any human experiences. In addition, a generalized advantage estimation was added to the loss function of the PPO algorithm, which allowed baselines in PPO algorithms to be self-adjusted. At first, the SMASS was modeled with the Nomoto model in a simulation waterway. Then, distances, obstacles, and prohibited areas were regularized as rewards or punishments, which were used to judge the performance and manipulation decisions of the vessel Subsequently, improved PPO was introduced to learn the action-reward model, and the neural network model after training was used to manipulate the SMASS's movement. To achieve higher reward values, the SMASS could find an appropriate path or navigation strategy by itself. After a sufficient number of rounds of training, a convincing path and manipulation strategies would likely be produced. Compared with the proposed approach of the existing methods, this approach is more effective in self-learning and continuous optimization and thus closer to human manipulation.\",\n \"Title: Health diagnosis of NC machine tool from user's perspective\\nYear: 2022\\n\\nAbstract: NC machines' health monitoring is important for manufacturing enterprises. In this paper, we propose a scheme to do the monitoring and diagnosis mainly via collecting the internal data generated by the inside sensors of NC machine tool. Then these data are analyzed by Principal Component Analysis (PCA) method to determine the health status. The experimental results show that this method has certain applicability and effectiveness for the health diagnosis of NC machine tools, and is of good value for large manufacturing enterprises, of which core competitiveness resides on the sufficient operation of these machines.\",\n \"Title: Spectrum Sharing in UAV-Assisted HetNet Based on CMB-AM Multi-Agent Deep Reinforcement Learning\\nYear: 2022\\n\\nAbstract: Unmanned aerial vehicle (UAV) assisted heterogeneous network (HetNet) is a promising solution to outdoor hotspots. This poster proposes a coordination-mini-batch with action mask (CMB-AM) multi-agent deep reinforcement learning (DRL) based resource allocation scheme for uplink spectrum sharing in a UAV-assisted two-tier heterogeneous network (Het-Net). We utilize a centralized training and distributed execution mechanism and consider the correlation among actions to make the agents collaborate implicitly. Due to independent state and collective reward design, our resource allocation scheme can be robust and scalable to the varying number of agents. Evaluation shows that the proposed scheme achieves better performance on the aspects of sum capacity, model applicability, and training stability than other baseline schemes.\",\n \"Title: A Two-Phase Optimization Model for Autonomous Electric Customized Bus Service Design\\nYear: 2022\\n\\nAbstract: Motivated by the requirements of highly effective customized bus (CB) service and by the rapid growth of autonomous electric vehicles (AEVs), this paper studies a new optimization model for the autonomous electric customized bus (AECB) service, aiming at minimizing operating costs and improving vehicles' efficient use. The proposed model contains two phases: (i) optimization of the vehicle routing, charging operation and passenger-to-vehicle assignment for the fixed travel demands, and (ii) re-optimization of the service according to real-time dynamic travel requests. A solution approach is developed to address the proposed model based on adaptive large neighborhood search (ALNS). The extensive empirical analysis, conducted by considering real-world data on a large-scale instance, demonstrates the efficiency of the proposed approach and the quality of the generated solutions.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":92,"string":"92"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":283,"string":"283"}}},{"rowIdx":284,"cells":{"question_id":{"kind":"string","value":"Hyoungshick Kim"},"question":{"kind":"string","value":"Generate an abstract for the title \"Secure and Efficient Three-Factor Protocol for Wireless Sensor Networks.\" using the following items: Wireless sensor networks, security protocols, authentication scheme, user impersonation attacks, user anonymity."},"answer":{"kind":"string","value":"Wireless sensor networks are widely used in many applications such as environmental monitoring, health care, smart grid and surveillance. Many security protocols have been proposed and intensively studied due to the inherent nature of wireless networks. In particular, Wu et al. proposed a promising authentication scheme which is sufficiently robust against various attacks. However, according to our analysis, Wu et al.'s scheme has two serious security weaknesses against malicious outsiders. First, their scheme can lead to user impersonation attacks. Second, user anonymity is not preserved in their scheme. In this paper, we present these vulnerabilities of Wu et al.'s scheme in detail. We also propose a new scheme to complement their weaknesses. We improve and speed up the vulnerability of the Wu et al. scheme. Security analysis is analyzed by Proverif and informal analysis is performed for various attacks."},"correct_answer":{"kind":"string","value":"Wireless sensor networks are widely used in many applications such as environmental monitoring, health care, smart grid and surveillance. Many security protocols have been proposed and intensively studied due to the inherent nature of wireless networks. In particular, Wu et al. proposed a promising authentication scheme which is sufficiently robust against various attacks. However, according to our analysis, Wu et al.'s scheme has two serious security weaknesses against malicious outsiders. First, their scheme can lead to user impersonation attacks. Second, user anonymity is not preserved in their scheme. In this paper, we present these vulnerabilities of Wu et al.'s scheme in detail. We also propose a new scheme to complement their weaknesses. We improve and speed up the vulnerability of the Wu et al. scheme. Security analysis is analyzed by Proverif and informal analysis is performed for various attacks."},"documents":{"kind":"list like","value":["Title: A Perfect Collision-Free Pseudonym System\nYear: 2011\n\nAbstract: For anonymous communication, the most popular method is to use pseudonyms instead of original identities. We previously demonstrated the possibility of a collision-free pseudonym system by uniquely assigning a permutation element to each network entity. We extend this idea by assigning k permutation elements to each entity for k ≥ 1. We analyse the randomness of the pseudonyms used in the proposed system to show the effect of k by varying k from 1 to 50. Our experimental results show that our pseudonym system can provide practical anonymity with k.","Title: Efficient channel selection using hierarchical clustering\nYear: 2012\n\nAbstract: Increases in the number of TV channels requires users to spend more time to select their preferred channels since the user interaction for browsing is practically limited to the conventional remote control with a two-way scrolling button. We formally define the problem to construct the optimal channel ordering which minimizes the seek distance in selecting channels and show this problem is NP-hard. In addition, we present a reasonable heuristic to solve this problem. The proposed method constructs an efficient channel ordering by applying a hierarchical clustering algorithm based on the frequencies of switching events between channels. We demonstrate the feasibility of this method by applying a number of well-known hierarchical clustering algorithms and evaluating the number of user inputs required for selecting channels. Our experimental results show that the proposed method significantly decreases the number of user inputs compared with the conventional methods.","Title: PIN selection policies: Are they really effective?\nYear: 2012\n\nAbstract: Users have conflicting sets of requirements when it comes to choosing Personal Identification Numbers (PINs) for mobile phones or other systems that use PINs for authentication: the conflict lies between the 'easy to remember' usability requirement and the 'hard to guess' security requirement. Users often ignore the security requirement and choose PINs that are easy to remember and reuse, making it also easy for attackers to guess and compromise them. Just as the password strength is controlled through various password policies, PIN selection policies may be used to help users choose stronger PINs and meet various security requirements. An example policy would not allow the use of the most commonly selected PINs. An online user study was conducted to investigate the effectiveness of such PIN selection policies, requesting the participants to choose PINs under some carefully designed policies. The participants were also asked to record the memorability (remembrance difficulty) score of each PIN, indicating how easy/hard it was to remember the selected PIN. Based on the entropies calculated on the collected PINs and their memorability scores, this paper demonstrates that restricting some number of commonly used PINs (e.g. restricting the 200 most commonly used ones) is beneficial: this type of policy would significantly increase the randomness of PINs without incurring significant memorability overhead. Our results also showed that any PIN- or PIN-pattern-based blacklisting policy should be constructed with caution since the total PIN space may become too small, making it easier for attackers to guess PINs.","Title: Scalable DRM system for media portability\nYear: 2007\n\nAbstract: We present a new digital rights management (DRM) system for media portability using dynamic multimedia adaptation. For a user to share multimedia resources over home network, several DRM technologies based on the domain have been introduced. Domain-based approaches enable users to access contents on multiple devices within the same domain. However, most of current DRM systems were only designed for a homogeneous environment where common AV profiles are supported. It is a challenge to share the domain contents between domain members with diverse capabilities while ensuring the protection of the intellectual property rights for the legally obtained contents. In this paper, we propose an architecture that enables DRM contents to be securely shared between various home devices in a seamless manner.","Title: RAD: Recipient-anonymous data delivery based on public routing proxies\nYear: 2011\n\nAbstract: This paper presents a Recipient-Anonymous DataDelivery (RAD), tailored and optimized for stable-topology networks. There is one simplistic approach for achieving recipient anonymity. If a message is equally broadcasted to all network entities (e.g., routers and hosts), an adversary cannot infer any traffic patterns for the intended recipient. While this technique is unconditionally secure, no one believes that this is a practical solution except in some special network environments since it requires extremely expensive traffic overhead. In this paper we realize this idea with an efficient multicast protocol by introducing the concept of a public routing proxy. A public routing proxy enables a sender to deliver a message to the intended recipient anonymously since the public routing proxy multicasts the message to a set of k network entities including the intended recipient. Thus, in the proposed protocol, the recipient's k-anonymity can be unconditionally guaranteed. We also demonstrate the practicality of the proposed protocol through intensive simulation based on well-known network topologies.","Title: A spatial cloaking framework based on range search for nearest neighbor search\nYear: 2009\n\nAbstract: For nearest neighbor search, a user queries a server for nearby points of interest (POIs) with his/her location information. Our aim is to protect the user's sensitive information against adversaries including the location-based service itself. Most research efforts have elaborated on reasonable trade-offs between privacy and utility. We propose a framework based on range search query without a trusted middleware. We design a query processing algorithm for the minimum set of candidate POIs by computing the local Voronoi diagram relevant to the cloaked region. Contrary to common belief that cloaking approaches using range search incur expensive processing and communication cost, the experimental results show that the framework incurs reasonable processing and communication overhead even for large cloaked regions.","Title: Achieving attestation with less effort: an indirect and configurable approach to integrity reporting\nYear: 2011\n\nAbstract: This paper proposes an indirect attestation paradigm for verifying the trustworthiness of end user platforms. This approach overcomes several criticisms of attestation by maintaining the user's freedom to choose their own software configurations and minimising the whitelist management overhead for the relying party. Each user platform defines its own acceptable software combination in terms of reference integrity measurements, and reports the local verification results to the relying party through a late-launched, trusted Platform Trust Service. The relying party simply checks this verification result and a security meta-policy that has been used to ensure the quality of the security checks performed locally. The Platform Trust Service is also responsible for reporting whether this meta-policy is satisfied. By configuring the meta-policy, the relying party selects an indirect attestation paradigm that best meets their high-level security requirements.","Title: Self-authorized public key management for home networks\nYear: 2007\n\nAbstract: This paper describes the key management method which allows secure communication channels between devices in home networks. Home network technologies have developed to enable various kinds of home devices to access the digital information between the devices. Without security framework, however, the digital information including a user's private data may be exposed to a malicious attacker. Although conventional public key cryptosystems generally provide security features such as confidentiality and integrity, the distribution of the keys is vulnerable to man-in-the-middle attack without a trusted third party. In general home networks are dynamically set up without relying on any pre-existing infrastructure or central administration. Therefore, we must implement key distribution schemes without the assumption of a trusted third party. In this paper, we present self-authorized public key management for home networks. Our idea is to bind the device owner's authorization information to the public key of a device. Our protocol enables the distribution of the authenticated public key using an identity-based encryption scheme. We also provide heuristic analysis of various security properties.","Title: Centrality prediction in dynamic human contact networks\nYear: 2012\n\nAbstract: Real technological, social and biological networks evolve over time. Predicting their future topology has applications to epidemiology, targeted marketing, network reliability and routing in ad hoc and peer-to-peer networks. The key problem for such applications is usually to identify the nodes that will be in more important positions in the future. Previous researchers had used ad hoc prediction functions. In this paper, we evaluate ways of predicting a node's future importance under three important metrics, namely degree, closeness centrality, and betweenness centrality, using empirical data on human contact networks collected using mobile devices. We find that node importance is highly predictable due to both periodic and legacy effects of human social behaviour, and we design reasonable prediction functions. However human behaviour is not the same in all circumstances: the centrality of students at Cambridge is best correlated both daily and hourly, no doubt due to hourly lecture schedules, while academics at conferences exhibit rather flat closeness centrality, no doubt because conference attendees are generally trying to speak to new people at each break. This highlights the utility of having a number of different metrics for centrality in dynamic networks, so as to identify typical patterns and predict behaviour. We show that the best-performing prediction functions are 25% more accurate on average than simply using the previous centrality value. These prediction functions can be efficiently computed in linear time, and are thus practical for processing dynamic networks in real-time.","Title: Hybrid spam filtering for mobile communication\nYear: 2009\n\nAbstract: Spam messages are an increasing threat to mobile communication. Several mitigation techniques have been proposed, including white and black listing, challenge-response and content-based filtering. However, none are perfect and it makes sense to use a combination rather than just one. We propose an anti-spam framework based on the hybrid of content-based filtering and challenge-response. A message, that has been classified as uncertain through content-based filtering, is checked further by sending a challenge to the message sender. An automated spam generator is unlikely to send back a correct response, in which case, the message is classified as spam. Our simulation results show the trade-off between the accuracy of anti-spam classifiers and the incurring traffic overhead, and demonstrate that our hybrid framework is capable of achieving high accuracy regardless of the content-based filtering algorithm being used.","Title: Effective measurement selection in truncated kernel density estimator: Voronoi mean shift algorithm for truncated kernels\nYear: 2011\n\nAbstract: The Gating/Truncation technique is adapted to choose relatively significant measurements rather than all measurements to speed up mean shift algorithm which is one of the well-known clustering algorithms in the field of computer vision. The conventional mean shift algorithm can be sensitive to selecting measurements since the measurements are truncated with a Gaussian window of a fixed size. In particular when a small gating window is selected, it cannot properly cluster data points located far from major clusters and thus it generates unwanted, small clusters. We present a robust gating technique for truncated mean shift algorithm based on a geometric structure called Voronoi diagram of a given data set. Unlike conventional gating/truncation techniques our proposed truncation technique can provide nonlinear truncation windows with variable sizes constructed by using the Voronoi diagram to effectively identify outlier points in clusters. We also demonstrate the feasibility of this technique by applying it on synthetic and real-world image data sets. The experimental results show that the proposed truncation technique provides a more robust clustering result compared to the conventional truncation techniques. The proposed algorithm can be effectively applied to denoising of images by removing background noise.","Title: Finding influential neighbors to maximize information diffusion in twitter\nYear: 2014\n\nAbstract: The problem of spreading information is a topic of considerable recent interest, but the traditional influence maximization problem is inadequate for a typical viral marketer who cannot access the entire network topology. To fix this flawed assumption that the marketer can control any arbitrary k nodes in a network, we have developed a decentralized version of the influential maximization problem by influencing k neighbors rather than arbitrary users in the entire network. We present several reasonable neighbor selection schemes and evaluate their performance with a real dataset collected from Twitter. Unlike previous studies using network topology alone or synthetic parameters, we use real propagation rate for each node calculated from the Twitter messages during the 2010 UK election campaign. Our experimental results show that information can be efficiently propagated in online social networks using neighbors with a high propagation rate rather than those with a high number of neighbors.","Title: How to Compare the Scientific Contributions between Research Groups\nYear: 2009\n\nAbstract: We present a method to analyse the scientific contributions between research\ngroups. Given multiple research groups, we construct their journal/proceeding\ngraphs and then compute the similarity/gap between them using network analysis.\nThis analysis can be used for measuring similarity/gap of the topics/qualities\nbetween research groups' scientific contributions. We demonstrate the\npracticality of our method by comparing the scientific contributions by Korean\nresearchers with those by the global researchers for information security in\n2006 - 2008. The empirical analysis shows that the current security research in\nSouth Korea has been isolated from the global research trend.","Title: Don't count the number of friends when you are spreading information in social networks\nYear: 2014\n\nAbstract: The problem of spreading information in social networks is a topic of considerable recent interest, but the conventional influence maximisation problem which selects a set of any arbitrary k nodes in a network as the initially activated nodes might be inadequate in a real-world social network -- cyber-stalkers try to initially spread a rumour through their neighbours only rather than arbitrary users selected from the entire network. To consider this more practical scenario, Kim and Eiko [16] introduced the optimisation problem to find influential neighbours to maximise information diffusion. We extend this model by introducing several important parameters such as user propagation rate on his (or her) neighbours to provide a more general and practical information diffusion model. We performed intensive simulations on several real-world network topologies (emails, blogs, Twitter and Facebook) to develop more effective information spreading schemes under this model. Unlike the results of previous research, our experimental results shows that information can be efficiently propagated in social networks using the propagation rate alone, even without consideration of the \"number of friends\" information. Moreover, we found that the naive random spreading would be used to efficiently spread information if k increases sufficiently (e.g. k = 4).","Title: We Are Still Vulnerable to Clickjacking Attacks: About 99ä% of Korean Websites Are Dangerous\nYear: 2013\n\nAbstract: Clickjacking is an attack that tricks victims into clicking on invisible elements of a web page to perform an unintended action that is advantageous for an attacker. To defend against clickjacking, many techniques have already been proposed, but it is still unclear whether they are effectively deployed in practice. We study how vulnerable Korean websites are to clickjacking attacks by performing real attacks on top 100 popular Korean websites as well as all the financial websites. Our results are quite significant: almost all Korean websites (about 99.2ä%) that we looked at are vulnerable to clickjacking attacks. Extending our observation to mobile websites, we can also obtain similar results.","Title: Influential Neighbours Selection for Information Diffusion in Online Social Networks\nYear: 2012\n\nAbstract: The problem of maximizing information diffusion through a network is a topic of considerable recent interest. A conventional problem is to select a set of any arbitrary k nodes as the initial influenced nodes so that they can effectively disseminate the information to the rest of the network. However, this model is usually unrealistic in online social networks since we cannot typically choose arbitrary nodes in the network as the initial influenced nodes. From the point of view of an individual user who wants to spread information as much as possible, a more reasonable model is to try to initially share the information with only some of its neighbours rather than a set of any arbitrary nodes; but how can these neighbours be effectively chosen? We empirically study how to design more effective neighbours selection strategies to maximize information diffusion. Our experimental results through intensive simulation on several real- world network topologies show that an effective neighbours selection strategy is to use node degree information for short-term propagation while a naive random selection is also adequate for long-term propagation to cover more than half of a network. We also discuss the effects of the number of initial activated neighbours. If we particularly select the highest degree nodes as initial activated neighbours, the number of initial activated neighbours is not an important factor at least for long-term propagation of information.","Title: Network analysis of temporal trends in scholarly research productivity.\nYear: 2012\n\nAbstract: We propose a method to identify the journals or proceedings that are most highly esteemed by a research group over some time frame. Using open publication databases, we identify the experts in the community, and analyse their publication pattern, and then use this as a guideline for evaluating scientific outputs of other groups of researchers publishing in the same domain. To illustrate the practicality of our method, we analyse the scientific output of Korean researchers in the security subject domain from 2004 to 2009, and comparing this groups' output with that of well-known researchers. Our empirical analysis demonstrates that there is a persistent gap between these two research groups' publications impact over this period, although the absolute number of journal publications greatly increased over recent years. (C) 2011 Elsevier Ltd. All rights reserved.","Title: What's in Twitter: I Know What Parties are Popular and Who You are Supporting Now!\nYear: 2013\n\nAbstract: In modern politics, parties and individual candidates must have an online presence and usually have dedicated social media coordinators. In this context, we study the usefulness of analysing Twitter messages to identify both the characteristics of political parties and the political leaning of users. As a case study, we collected the main stream of Twitter related to the 2010 UK General Election during the associated period -- gathering around 1,150,000 messages from about 220,000 users. We examined the characteristics of the three main parties in the election and highlighted the main differences between parties. First, Lab our members were the most active and influential during the election while Conservative members were the most organized to promote their activities. Second, the websites and blogs that each political party's members supported are clearly different from those that all the other political parties' members supported. From these observations, we develop a simple and practical classification method which uses the number of Twitter messages referring to a particular political party. The experimental results showed that the proposed classification method achieved about 86% classification accuracy and outperforms other classification methods that require expensive costs for tuning classifier parameters and/or knowledge about network topology.","Title: Privacy-enhanced public view for social graphs\nYear: 2009\n\nAbstract: We consider the problem of releasing a limited public view of a sensitive graph which reveals at least k edges per node. We are motivated by Facebook's public search listings, which expose user profiles to search engines along with a fixed number of each user's friends. If this public view is produced by uniform random sampling, an adversary can accurately approximate many sensitive features of the original graph, including the degree of individual nodes. We propose several schemes to produce public views which hide degree information. We demonstrate the practicality of our schemes using real data and show that it is possible to mitigate inference of degree while still providing useful public views.","Title: Privacy-Enhancing Queries In Personalized Search With Untrusted Service Providers\nYear: 2012\n\nAbstract: For personalized search, a user must provide her personal information. However, this sometimes includes the user's sensitive information about individuals such as health condition and private lifestyle. It is not sufficient just to protect the communication channel between user and service provider. Unfortunately, the collected personal data can potentially be misused for the service providers' commercial advantage (e.g. for advertising methods to target potential consumers). Our aim here is to protect user privacy by filtering out the sensitive information exposed from a user's. query input at the system level. We propose a framework by introducing the concept of query generalizer. Query generalizer is a middleware that takes a query for personalized search, modifies the query to hide user's sensitive personal information adaptively depending on the user's privacy policy, and then forwards the modified query to the service provider. Our experimental results show that the best-performing query generalization method is capable of achieving a low traffic overhead within a reasonable range of user privacy. The increased traffic overhead varied from 1.0 to 3.3 times compared to the original query.","Title: A new collision-free pseudonym scheme in mobile ad hoc networks\nYear: 2009\n\nAbstract: A mobile ad hoc network (MANET) is a decentralized network of mobile nodes. Due to the broadcast nature of radio transmissions, communication in MANETs is more susceptible to malicious traffic analysis. An interesting problem is how to thwart malicious traffic analysis. Most anonymous communication protocols are based on the pseudonyms of mobile nodes. However, conventional pseudonym schemes have some limitations such as collisions of pseudonyms and high computational complexity due to the use of cryptographic hash functions. Collisions of identities are not desirable since they are the main causes for reduced effective bandwidth, increased energy consumption and non-deterministic data delivery. In this paper, we propose a new collision-free pseudonym scheme to enable anonymous communication. In our approach, each node generates pseudonyms by using a permutation matrix without collisions. The challenging issue is how to store the overall permutation matrix. It is practically hard to assume that mobile nodes maintain the permutation matrix due to the limitation of resources. Therefore we design the online computation of each node's own pseudonym without loading the overall matrix.","Title: Phishing detection with popular search engines: simple and effective\nYear: 2011\n\nAbstract: We propose a new phishing detection heuristic based on the search results returned from popular web search engines such as Google, Bing and Yahoo. The full URL of a website a user intends to access is used as the search string, and the number of results returned and ranking of the website are used for classification. Most of the time, legitimate websites get back large number of results and are ranked first, whereas phishing websites get back no result and/or are not ranked at all. To demonstrate the effectiveness of our approach, we experimented with four well-known classification algorithms --- Linear Discriminant Analysis, Naïve Bayesian, K -Nearest Neighbour, and Support Vector Machine --- and observed their performance. The K -Nearest Neighbour algorithm performed best, achieving true positive rate of 98% and false positive and false negative rates of 2%. We used new legitimate websites and phishing websites as our dataset to show that our approach works well even on newly launched websites/webpages --- such websites are often misclassified in existing blacklisting and whitelisting approaches.","Title: An Experimental Evaluation of Robustness of Networks\nYear: 2013\n\nAbstract: Models of conflict in networks provide insights into applications ranging from epidemiology to guerilla warfare. Barabási, Albert, and Jeong modeled selective attacks on networks in which an attacker targets high-order nodes to destroy connectivity; Nagaraja and Anderson extended this to iterated attacks where the attacker and defender take turns removing and rebuilding nodes and edges according to given strategies. We extend the iterative model by introducing the cost required to perform network operations. This gives a much finer granularity than previous models, whether we are interested in network resilience against random failures or intentional attacks. We empirically study how to design more effective attacks and/or defenses through intensive simulation on several well-known network topologies, including the three real-world networks. In particular, an effective defense against many attacks is to add new links connecting low-centrality nodes to maintain the overall balance of network centrality.","Title: On the Effectiveness of Pattern Lock Strength Meters: Measuring the Strength of Real World Pattern Locks\nYear: 2015\n\nAbstract: We propose an effective pattern lock strength meter to help users choose stronger pattern locks on Android devices. To evaluate the effectiveness of the proposed meter with a real world dataset (i.e., with complete ecological validity), we created an Android application called EnCloud that allows users to encrypt their Dropbox files. 101 pattern locks generated by real EnCloud users were collected and analyzed, where some portion of the users were provided with the meter support. Our statistical analysis indicates that about 10% of the pattern locks that were generated without the meter support could be compromised through just 16 guessing attempts. As for the pattern locks that were generated with the meter support, that number goes up to 48 guessing attempts, showing significant improvement in security. Our recommendation is to implement a strength meter in the next version of Android.","Title: Visualizing Privacy Risks Of Mobile Applications Through A Privacy Meter\nYear: 2015\n\nAbstract: When it comes to installing mobile applications on Android devices, users tend to ignore privacy warning messages about permissions being requested. Warning messages are often shown too late and are hard to interpret for normal users. To improve users' awareness of potential privacy implications of installing an application, we designed a \"privacy meter\" that visualizes the risks (in a slider bar format) imposed by the types of permissions being requested. Interpreting and understanding privacy risks become quick and easy.Our lab study shows that the privacy meter is the most effective solution compared to Google's existing permission screens and privacy fact feature. With the privacy meter in place, only about 26% of participants recommended applications that have high privacy risks to their friends and family members. That is a significant improvement from the 61% of participants who recommended high risk applications when Google's permission screens were used. The time taken to make recommendation decisions, on average, also dropped from 72 seconds to 26 seconds when the privacy meter was used.","Title: A Framework for Security Services Based on Software-Defined Networking\nYear: 2015\n\nAbstract: This paper proposes a framework for security services using Software-Defined Networking (SDN) and specifies requirements for such a framework. It describes two representative security services, such as (i) centralized firewall system and (ii) centralized DDoS-attack mitigation system. For each service, this paper discusses the limitations of legacy systems and presents a possible SDN-based system to protect network resources by controlling suspicious and dangerous network traffic that can be regarded as security attacks.","Title: SBUS: Smart e-Bus Battery Substitution Scheme in Vehicular Networks\nYear: 2015\n\nAbstract: This paper proposes a Smart e-Bus Battery Substitution Scheme (called SBUS), tailored and optimized for the commute service of e-Buses using a cloud-based management system. To the best of our knowledge, our scheme is the first attempt to investigate the efficient battery replacement of e-Buses in road networks, based on the trajectories (i.e., Travel routes) of e-Buses in road networks. Through simulations, it is shown that our SBUS scheme outperforms baselines in a road network with multiple bus lines.","Title: A Survey on Interfaces to Network Security Functions in Network Virtualization\nYear: 2015\n\nAbstract: Network Functions Virtualization (NFV) opens new opportunities and challenges for security community. Unlike existing physical network infrastructure, in a virtualized network platform, security services can be dynamically deployed and maintained to cope with the threat of sophisticated network attacks that are increasing over time. This paper surveys the activity that many security vendors and Internet service providers are trying to define common interfaces for NFV-based security services through the analysis of use cases and related technologies. This activity is currently lead by Internet Engineering Task Force (IETF) that is an international Internet standardization organization.","Title: Privacy Preserving Nearest Neighbor Search Based on Topologies in Cellular Networks\nYear: 2015\n\nAbstract: As the popularity of location-based services (LBSes) is increasing, the location privacy has become a main concern. Among the rich collection of location privacy techniques, the spatial cloaking is one of the most popular techniques. In this paper, we propose a new spatial cloaking technique to hide a user's location under a cloaking of the serving base station (SeNB) and anonymize SeNB with a group of dummy locations in the neighboring group of another base station as central eNB (CeNB). Unlike the most existing approaches for selecting a dummy location, such as the center of a virtual circle, we select a properly chosen dummy location from real locations of eNBs to minimize side information for an adversary. Our experimental results show that the proposed scheme can achieve a reasonable degree of accuracy (>96%) for nearest neighbor services while providing a high level of location privacy.","Title: KaaSP: keying as a service provider for small and medium enterprises using untrusted cloud services\nYear: 2014\n\nAbstract: Cloud computing provides a framework for allowing remote and nearly instantaneous access to data and resources from any location in the world with an Internet connection. However, it faces privacy concerns since cloud service providers can also access user data on their storage. Although several encryption services and applications were introduced for personal users, it is still questionable whether such services can effectively be deployed for enterprises due to their lack of scalability. We propose a new access control system that incorporates encryption, based on access via a third-party key management service. The proposed system introduces a new entity named a Keying as a Service Provider (KaaSP) to more securely provide a data encryption service. In our approach, data encryption keys are generated through a negotiation with the KaaSP which would not have access to all key parts. Therefore, even if petitioned by a powerful adversary such as a law enforcement organization or breached by an attack, the data could not be leaked. Moreover, user data on the cloud storage can be protected from access attempts made by a lost device controlled by an unauthorized user since a lost device's credential for authentication can instantly be revoked. Additionally, the controlling organization can seamlessly edit access credentials via this cryptographic framework.","Title: Analyzing Unnecessary Permissions Requested By Android Apps Based On Users' Opinions\nYear: 2014\n\nAbstract: Many existing mobile apps request for unnecessary permissions knowing that users often ignore permission warning messages. We conducted an online user study to investigate how users feel about permissions being requested by both free and paid Android apps. Results show that users tend to feel that free Android apps request for more unnecessary permissions compared to paid apps. Users also felt that older apps (those that are previously released and have gone through several updates) request for more unnecessary permissions than those that are newly released. Based on that observation, we surmise that many developers initially publish apps that require a small set of permissions (so that users are not discouraged from installing an app), and gradually add more permissions to their apps through updates.","Title: Enhancing Conformance Testing Using Symbolic Execution for Network Protocols\nYear: 2015\n\nAbstract: Security protocols are notoriously difficult to get right, and most go through several iterations before their hidden security vulnerabilities, which are hard to detect, are triggered. To help protocol designers and developers efficiently find non-trivial bugs, we introduce SYMCONF, a practical conformance testing tool that generates high-coverage test input packets using a conformance test suite and symbolic execution. Our approach can be viewed as the combination of conformance testing and symbolic execution: 1) it first selects symbolic inputs from an existing conformance test suite; 2) it then symbolically executes a network protocol implementation with the symbolic inputs; and 3) it finally generates high-coverage test input packets using a conformance test suite. We demonstrate the feasibility of this methodology by applying SYMCONF to the generation of a stream of high quality test input packets for multiple implementations of two network protocols, the Kerberos Telnet protocol and Dynamic Host Configuration Protocol (DHCP), and discovering non-trivial security bugs in the protocols.","Title: A Healthcare Information System For Secure Delivery And Remote Management Of Medical Records\nYear: 2016\n\nAbstract: With the rapid merger of healthcare business and information technology, more healthcare institutions and medical practices are sharing information. Since these records often contain patients' sensitive personal information, Healthcare Information Systems (HISs) should be properly designed to manage these records in a secure manner. We propose a novel security design for the HIS complying with the security and privacy rules. The proposed system defines protocols to ensure secure delivery of medical records over insecure public networks and reliable management of medical record in the remote server without incurring excessive costs to implement services for security. We demonstrate the practicality of the proposed system through a security analysis and performance evaluation.","Title: Keyboard or keylogger?: A security analysis of third-party keyboards on Android\nYear: 2015\n\nAbstract: Use of third-party keyboards makes Android more flexible and customizable. However, we demonstrate their potential security risks by implementing a proof-of-concept keylogger that can effectively steal users' sensitive keystrokes with 81 popular websites (out of 100 tested websites). We also empirically analyzed the security behaviors of 139 keyboard applications that were available on Google Play. Our study results show that the majority of existing keyboard applications (84 out of 139) could be potentially misused as malicious keyloggers. To avoid such keylogging attacks, we discuss possible defense mechanisms.","Title: Devil in a box: Installing backdoors in electronic door locks\nYear: 2015\n\nAbstract: Electronic door locks must be carefully designed to allow valid users to open (or close) a door and prevent unauthorized people from opening (or closing) the door. However, lock manufacturers have often ignored the fact that door locks can be modified by attackers in the real world. In this paper, we demonstrate that the most popular electronic door locks can easily be compromised by inserting a malicious hardware backdoor to perform unauthorized operations on the door locks. Attackers can replay a valid DC voltage pulse to open (or close) the door in an unauthorized manner or capture the user's personal identification number (PIN) used for the door lock.","Title: Surpass: System-initiated User-replaceable Passwords\nYear: 2015\n\nAbstract: System-generated random passwords have maximum password security and are highly resistant to guessing attacks. However, few systems use such passwords because they are difficult to remember. In this paper, we propose a system-initiated password scheme called \\\"Surpass\\\" that lets users replace few characters in a random password to make it more memorable. We conducted a large-scale online study to evaluate the usability and security of four Surpass policies, varying the number of character replacements allowed from 1 to 4 in randomly-generated 8-character passwords. The study results suggest that some Surpass policies (with 3 and 4 character replacements) outperform by 11% to 13% the original randomly-generated password policy in memorability, while showing a small increase in the percentage of cracked passwords. When compared to a user-generated password complexity policy (that mandates the use of numbers, symbols, and uppercase letters) the Surpass policy with 4-character replacements did not show statistically significant inferiority in memorability. Our qualitative lab study showed similar trends. This Surpass policy demonstrated significant superiority in security though, with 21% fewer cracked passwords than the user-generated password policy.","Title: An Empirical Study of Click Fraud in Mobile Advertising Networks\nYear: 2015\n\nAbstract: Smartphone advertisement is increasingly used among many applications and allows developers to obtain revenue through in-app advertising. Our study aims at identifying potential security risks of a type of mobile advertisement where advertisers are charged for their advertisements only when a user clicks (or touches) on the advertisements in their applications. In the Android platform, we design an automated click generation attack and empirically evaluate eight popular advertising networks by performing real attacks on them. Our experimental results show that six advertising networks (75%) out of eight (Millennial Media, App Lovin, Ad Fit, Mdot M, Rev Mob and Cauly Ads) are vulnerable to our attacks. We also discuss how to develop effective defense mechanisms to mitigate such automated click fraud attacks.","Title: Visual Honey Encryption: Application to Steganography\nYear: 2015\n\nAbstract: Honey encryption (HE) is a new technique to overcome the weakness of conventional password-based encryption (PBE). However, conventional honey encryption still has the limitation that it works only for binary bit streams or integer sequences because it uses a fixed distribution-transforming encoder (DTE). In this paper, we propose a variant of honey encryption called visual honey encryption which employs an adaptive DTE in a Bayesian framework so that the proposed approach can be applied to more complex domains including images and videos. We applied this method to create a new steganography scheme which significantly improves the security level of traditional steganography.","Title: Bypassing the Integrity Checking of Rights Objects in OMA DRM: a Case Study with the MelOn Music Service\nYear: 2016\n\nAbstract: Commercial digital music is typically distributed in the music source market via Digital Rights Management systems (DRM). DRM systems help remotely control the music contents. The Open Mobile Alliance (OMA) DRM became the de facto standard after major market adoption because of its support for a wide variety of different business and usage models. In OMA DRM, a popular business model is a (monthly) subscription enforced by controlling the period of playback time; once the given period of time expires, the music cannot be played. In this paper, we demonstrate how to bypass the integrity checking of the rights object in the OMA DRM system through a case study of MelOn (a well-known music distribution service in South Korea) by reverse engineering its media player equipped with a DRM agent.","Title: Threat Assessment in the Cloud Environment: A Quantitative Approach for Security Pattern Selection\nYear: 2016\n\nAbstract: Cloud computing has emerged as a fast-growing technology in the past few years. It provides a great flexibility for storing, sharing and delivering data over the Internet without investing on new technology or resources. In spite of the development and wide array of cloud usage, security perspective of cloud computing still remains its infancy. Security challenges faced by cloud environment becomes more complicated when we include various stakeholders' perspectives. In a cloud environment, security perspectives and requirements are usually designed by software engineers or security experts. Sometimes clients' requirements are either ignored or given a very high importance. In order to implement cloud security by providing equal importance to client organizations, software engineers and security experts, we propose a new methodology in this paper. We use Microsoft's STRIDE-DREAD model to assess threats existing in the cloud environment and also to measure its consequences. Our aim is to rank the threats based on the nature of its severity, and also giving a significant importance for clients' requirements on security perspective. Our methodology would act as a guiding tool for security experts and software engineers to proceed with securing process especially for a private or a hybrid cloud. Once threats are ranked, we provide a link to a well-known security pattern classification. Although we have some security pattern classification schemes in the literature, we need a methodology to select a particular category of patterns. In this paper, we provide a novel methodology to select a set of security patterns for securing a cloud software. This methodology could aid a security expert or a software professional to assess the current vulnerability condition and prioritize by also including client's security requirements in a cloud environment.","Title: Encryption is Not Enough: Inferring User Activities on KakaoTalk with Traffic Analysis.\nYear: 2015\n\nAbstract: Many people started being concerned about their privacy in delivering private chats, photographs, contacts and other personal information through mobile instant messaging services. Fortunately, in the majority of mobile instant messaging services, encrypted communication channels e.g., using the SSL/TLS protocols are used by default to protect delivered messages against eavesdropping attacks. In this paper, however, we show that encryption is not enough. For example, in a real world service named KakaoTalk, many usersu0027 online activities can effectively be identified with 99.7i¾?% accuracy even though traffic is encrypted. We present a practical traffic analysis attack using a supervised machine learning technique.","Title: PassBYOP: Bring Your Own Picture for Securing Graphical Passwords.\nYear: 2016\n\nAbstract: PassBYOP is a new graphical password scheme for public terminals that replaces the static digital images typically used in graphical password systems with personalized physical tokens, herein in the form of digital pictures displayed on a physical user-owned device such as a mobile phone. Users present these images to a system camera and then enter their password as a sequence of selections on liv...","Title: SAN: Self-Adaptive Navigation for Drone Battery Charging in Wireless Drone Networks.\nYear: 2016\n\nAbstract: This paper introduces an optimal path finding problem for drone battery charging where their batteries should be charged for the travel from a source to a destination as needed. We present a practically reasonable heuristic to solve the problem by monitoring drones' battery status and traffic conditions in real time through a cloud-based service called traffic control center. This study will be the cornerstone of path finding problems for drone battery charging in drone networks.","Title: Detecting False Emergency Requests Using Callers' Reporting Behaviors and Locations\nYear: 2016\n\nAbstract: This paper introduces a security framework to detect false emergency requests, which might significantly disturb actual rescue operations for emergency services. We design a threshold-based false request detection algorithm named FRDA to effectively filter out false requests, which is based on a reasonable scoring formula to automatically evaluate the trustworthiness of emergency requests with the caller's reporting behavior and location. This study will be a basis for developing mitigation techniques to deal with false emergency requests.","Title: On the Guessability of Resident Registration Numbers in South Korea.\nYear: 2016\n\nAbstract: This paper studies a potential risk of using real name verification systems that are prevalently used in Korean websites. Upon joining a website, users are required to enter their Resident Registration Number RRN to identify themselves. We adapt guessing theory techniques to measure RRN security against a trawling attacker attempting to guess victim's RRN using some personal information such as name, sex, and location that are publicly available e.g., on Facebook. We evaluate the feasibility of performing statistical-guessing attacks using a real-world dataset consisting of 2,326 valid name and RRN pairs collected from several Chinese websites such as Baidu. Our results show that about 4,892.5 trials are needed on average to correctly guess a RRN. Compared to the brute-force attack, our statistical-guessing attack, on average, runs about 6.74 times faster.","Title: POSTER: WiPING: Wi-Fi signal-based PIN Guessing attack.\nYear: 2016\n\nAbstract: This paper presents a new type of online password guessing attack called \\\"WiPING\\\" (Wi-Fi signal-based PIN Guessing attack) to guess a victim's PIN (Personal Identification Number) within a small number of unlock attempts. WiPING uses wireless signal patterns identified from observing sequential finger movements involved in typing a PIN to unlock a mobile device. A list of possible PIN candidates is generated from the wireless signal patterns, and is used to improve performance of PIN guessing attacks. We implemented a proof-of-concept attack to demonstrate the feasibility of WiPING. Our results showed that WiPING could be practically effective: while pure guessing attacks failed to guess all 20 PINs, WiPING successfully guessed two PINs.","Title: Privacy-preserving nearest neighbor queries using geographical features of cellular networks.\nYear: 2017\n\nAbstract: Although location-based services (LBSes), such as nearest neighbor query, have become popular, privacy remains a challenging issue for users. Many privacy preserving techniques have been proposed, but their complexity, insufficiency, and time consumption make them unattractive to users, who prefer accuracy and quickness. To address this limitation, we introduce a framework to protect user privacy for nearest neighbor queries by utilizing the basic geographical features of cellular networks. In the proposed framework, we provide two layers of spatial anonymity such that the user’s location is not directly provided to a location service provider. Based on the features of the cellular network (e.g., LTE) at the first layer, the user’s location is kept hidden under the cloaking of the base station (eNB) that provides a network connectivity to serve the user (SeNB). At the second layer, we anonymize SeNB in a group of dummy locations neighboring a central eNB (CeNB), all of which have the same query probability. Unlike most existing approaches with faked dummy locations, the proposed framework depends on real locations of eNBs to minimize the likelihood that side information might be exposed to an adversary. Moreover, our model is motivated by the practicality of employing the ubiquity of cellular networks and their geographical features. The simulation results show that the proposed scheme can achieve a decent degree of accuracy (> 98%) while providing strong privacy guarantees.","Title: Security challenges with network functions virtualization.\nYear: 2017\n\nAbstract: The advent of network functions virtualization (NFV) has revolutionized numerous network-based applications due to its several benefits such as flexibility, manageability, scalability, and security. By the software-based virtualization of network functions on a single infrastructure, NFV provides users with a framework that dynamically provisions various network services in a flexible manner. However, NFV faces several security challenges (e.g., multi-tenancy and live migration) which make it vulnerable to some cybersecurity attacks (e.g., side-channel attacks and shared resource misuse attacks). In this paper, we provide an overview of NFV, discuss potentially serious security threats on NFV and introduce effective countermeasures to mitigate those threats. Finally, we suggest some practical solutions to provide a trustworthy platform for NFV.","Title: Analysis and comparison of fax spam detection algorithms.\nYear: 2017\n\nAbstract: Spam detection is one of the important problems in these days. Many spam detection methods were proposed, but fax spam detection is not popular. It not easy to directly use existing content-based spam detection methods for fax documents because the documents are processed as image rather than text. In this paper, we propose a fax spam detection framework which is based on keyword patterns by using an Optical Character Recognition (OCR) technique. To demonstrate how effective the proposed framework is, we analyze and compare three fax spam detection algorithms (rule based method, SVM based method, and naïve Bayesian based method) with 219 normal and 212 spam documents. Our recommendation is to use naïve Bayesian based method which is capable of achieving an accuracy of 92.49%.","Title: A flexible architecture for orchestrating network security functions to support high-level security policies.\nYear: 2017\n\nAbstract: Network Functions Virtualization (NFV) has provided a new way to design and deploy network security services, but it may fail to build a practically useful ecosystem that seamlessly integrates network security services if there is no standard interface between them. We propose a generic architecture for security management service based on Network Security Functions (NSF) using NFV. The proposed architecture allows users to define their security requirements in a user-friendly manner by providing the users with high-level security interfaces that do not require specific information about network resources and protocols. We design basic components (e.g., Security policy manager, NSF capability manager, Application logic, Policy updater and Event collector) and interfaces for the proposed architecture. We introduce three use cases: (1) blacklists of dangerous domains, (2) time-dependent access control policies and (3) detection of suspicious calls for VoIP-VoLTE services. We also explain how to implement our proposed architecture with an illustrative example. Furthermore, we discuss several technical challenges to deploy the proposed architecture in a real network environment.","Title: Wrong Siren! A Location Spoofing Attack on Indoor Positioning Systems: The Starbucks Case Study.\nYear: 2017\n\nAbstract: The Internet of Things interconnects a mass of billions devices, from smartphones to cars, to provide convenient services to people. This gives immediate access to various data about the objects and the environmental context -- leading to smart services and increased efficiency. A number of retail stores have started to adopt IoT enabled services to attract customers. In particular, thanks to indoor proximity technologies, it is possible to introduce location-based smart services to customers, for example, transmitting identifiable signals that represent the locations of stores. In this article, we investigate a potential security risk involved in such technologies: physical signals used as identifiers can be captured and forged easily with today's widely available IoT software for implementing location spoofing attacks. We highlight this security risk by providing a case study: an in-depth security analysis of the recently launched Starbucks service called Siren Order.","Title: Security and Privacy Challenges in the Internet of Things [Security and Privacy Matters].\nYear: 2017\n\nAbstract: This is the first installment of the new \"Security and Privacy Matters\" column in IEEE Consumer Electronics Magazine. Security and privacy are always at the heart of everything that happens in the Consumer Electronics (CE) industry. This column aims to provide insight on various aspects of security and privacy in the CE industry.","Title: TARD: Temporary Access Rights Delegation for guest network devices.\nYear: 2017\n\nAbstract: Abstract Many cryptographic protocols were developed to support efficient group membership operations. Although those schemes can be extensively used for controlling temporary access with guest devices which do occur in many real world situations, those schemes incur a significant management overhead. For guest devices, we propose a scheme without heavy key management overheads— T emporary A ccess R ights D elegation (TARD). The proposed scheme uses a cryptographic token that can be securely constructed by a one-way function chain, used for granting a temporary membership to a guest device. Our analysis shows that the proposed scheme is theoretically secure and outperforms the certificate-based authentication schemes.","Title: Forensic analysis of the backup database file in KakaoTalk messenger\nYear: 2017\n\nAbstract: Instant messaging services should be designed to securely protect their users' personal contents such as chat messages, photos and video clips against a wide range of attacks. In general, such contents are securely encrypted in storage. In this paper, however, we demonstrated that the backup database file for chat messages in KakaoTalk (the most popularly used instant messaging service in Republic of Korea, http://www.kakao.com/talk/en) can be leaked to unauthorized users. We carefully examined the backup procedure in KakaoTalk through reverse engineering the KakaoTalk application to analyze how the backup database file was encrypted and the encryption key can be generated. Our analysis showed that the encrypted database is susceptible to off-line password guessing attacks. Based on this finding, we recommend that a secure key generation technique should be designed to improve resistance against offline password guessing attacks by using a random secret number to generate the encryption key.","Title: I'm too Busy to Reset my LinkedIn Password: On the Effectiveness of Password Reset Emails.\nYear: 2017\n\nAbstract: A common security practice used to deal with a password breach is locking user accounts and sending out an email to tell users that they need to reset their password to unlock their account. This paper evaluates the effectiveness of this security practice based on the password reset email that LinkedIn sent out around May 2016, and through an online survey conducted on 249 LinkedIn users who received that email. Our evaluation shows that only about 46% of the participants reset their passwords. The mean time taken to reset password was 26.3 days, revealing that a significant proportion of the participants reset their password a few weeks, or even months after first receiving the email. Our findings suggest that more effective persuasive measures need to be added to convince users to reset their password in a timely manner, and further reduce the risks associated with delaying password resets.","Title: DDoS Attack Mitigation in Internet of Things Using Software Defined Networking.\nYear: 2017\n\nAbstract: Securing Internet of Things (IoT) systems is a challenge because of its multiple points of vulnerability. A spate of recent hacks and security breaches has unveiled glaring vulnerabilities in the IoT. Due to the computational and memory requirement constraints associated with anomaly detection algorithms in core networks, commercial in-line (part of the direct line of communication) Anomaly Detection Systems (ADSs) rely on sampling-based anomaly detection approaches to achieve line rates and truly-inline anomaly detection accuracy in real-time. However, packet sampling is inherently a lossy process which might provide an incomplete and biased approximation of the underlying traffic patterns. Moreover, commercial routers uses proprietary software making them closed to be manipulated from the outside. As a result, detecting malicious packets on the given network path is one of the most challenging problems in the field of network security. We argue that the advent of Software Defined Networking (SDN) provides a unique opportunity to effectively detect and mitigate DDoS attacks. Unlike sampling-based approaches for anomaly detection and limitation of proprietary software at routers, we use the SDN infrastructure to relax the sampling-based ADS constraints and collect traffic flow statistics which are maintained at each SDN-enabled switch to achieve high detection accuracy. In order to implement our idea, we discuss how to mitigate DDoS attacks using the features of SDN infrastructure.","Title: Boosting the Guessing Attack Performance on Android Lock Patterns with Smudge Attacks.\nYear: 2017\n\nAbstract: Android allows 20 consecutive fail attempts on unlocking a device. This makes it difficult for pure guessing attacks to crack user patterns on a stolen device before it permanently locks itself. We investigate the effectiveness of combining Markov model-based guessing attacks with smudge attacks on unlocking Android devices within 20 attempts. Detected smudges are used to pre-compute all the possible segments and patterns, significantly reducing the pattern space that needs to be brute-forced. Our Markov-model was trained using 70% of a real-world pattern dataset that consists of 312 patterns. We recruited 12 participants to draw the remaining 30% on Samsung Galaxy S4, and used smudges they left behind to analyze the performance of the combined attack. Our results show that this combined method can significantly improve the performance of pure guessing attacks, cracking 74.17% of patterns compared to just 13.33% when the Markov model-based guessing attack was performed alone---those results were collected from a naive usage scenario where the participants were merely asked to unlock a given device. Even under a more complex scenario that asked the participants to use the Facebook app for a few minutes---obscuring smudges were added as a result---our combined attack, at 31.94%, still outperformed the pure guessing attack at 13.33%. Obscuring smudges can significantly affect the performance of smudge-based attacks. Based on this finding, we recommend that a mitigation technique should be designed to help users add obscurity, e.g., by asking users to draw a second random pattern upon unlocking a device.","Title: SysPal: System-Guided Pattern Locks for Android\nYear: 2017\n\nAbstract: To improve the security of user-chosen Android screen lock patterns, we propose a novel system-guided pattern lock scheme called \"SysPal\" that mandates the use of a small number of randomly selected points while selecting a pattern. Users are given the freedom to use those mandated points at any position. We conducted a large-scale online study with 1,717 participants to evaluate the security and usability of three SysPal policies, varying the number of mandatory points that must be used (upon selecting a pattern) from one to three. Our results suggest that the two SysPal policies that mandate the use of one and two points can help users select significantly more secure patterns compared to the current Android policy: 22.58% and 23.19% fewer patterns were cracked. Those two SysPal policies, however, did not show any statistically significant inferiority in pattern recall success rate (the percentage of participants who correctly recalled their pattern after 24 hours). In our lab study, we asked participants to install our screen unlock application on their own Android device, and observed their real-life phone unlock behaviors for a day. Again, our lab study did not show any statistically significant difference in memorability for those two SysPal policies compared to the current Android policy.","Title: Design Of A Secure Digital Recording Protection System With Network Connected Devices\nYear: 2017\n\nAbstract: We present a new recording protection system for network connected devices that belong to a user's personal network. To avoid illegal redistribution of the recorded contents through Internet, a proper content protection technology is required. However, conventional recording protection systems all lack sharing of the recorded contents without an online connection to a remote content service. Our recording protection system is designed to avoid complicated membership controls which are generally required in the existing solutions. To show the feasibility of the proposed recording protection system, we implemented a prototype with popularly used encryption algorithms (AES and RSA-OAEP). The experimental results of our prototype demonstrate that the execution time overheads incurred by the proposed system seem acceptable enough.","Title: Towards Automated Exploit Generation For Embedded Systems\nYear: 2016\n\nAbstract: Manual vulnerability discovery and exploit development on an executable are very challenging tasks for developers. Therefore, the automation of those tasks is becoming interesting in the field of software security. In this paper, we implement an approach of automated exploit generation for firmware of embedded systems by extending an existing dynamic analysis framework called Avatar. Embedded systems occupy a significant portion of the market but lack typical security features found on general purpose computers, making them prone to critical vulnerabilities. We discuss several techniques to automatically discover vulnerabilities and generate exploits for embedded systems, and evaluate our proposed approach by generating exploits for two vulnerable firmware written for a popular ARM Cortex-M3 microcontroller.","Title: Empirical Analysis Of Ssl/Tls Weaknesses In Real Websites: Who Cares?\nYear: 2016\n\nAbstract: As SSL/TLS has become the de facto standard Internet protocol for secure communication in recent years, its security issues have also been intensively studied. Even though several tools have been introduced to help administrators know which SSL/TLS vulnerabilities exist in their network hosts, it is still unclear whether the best security practices are effectively adopted to fix those vulnerabilities in real-world applications. In this paper, we present the landscape of real websites about SSL/TLS weaknesses through an automatic analysis of the possibilities of six representative SSL/TLS attacks-Heartbleed, POODLE, CCS injection, FREAK, Logjam and DROWN-on popular websites. Surprisingly, our experiments show that 45% and 52.6% of top 500 most popular global and Korean websites are still vulnerable to at least one of those attacks, respectively. We also observed several interesting trends in how websites were vulnerable to those attacks. Our findings suggest that better tools and education programs for SSL/TLS security are needed to help administrators keep their systems up-to-date with security patches.","Title: Preventing Dns Amplification Attacks Using The History Of Dns Queries With Sdn\nYear: 2017\n\nAbstract: Domain Name System (DNS) amplification attack is a sophisticated Distributed Denial of Service (DDoS) attack by sending a huge volume of DNS name lookup requests to open DNS servers with the source address spoofed as a victim host. However, from the point of view of an individual network resource such as DNS server and switch, it is not easy to mitigate such attacks because a distributed attack could be performed with multiple DNS servers and/or switches. To overcome this limitation, we propose a novel security framework using Software-Defined Networking (SDN) to store the history of DNS queries as an evidence to distinguish normal DNS responses from attack packets. Our evaluation results demonstrate that the network traffic for DNS amplification attack can completely be blocked under various network conditions without incurring a significant communication overhead.","Title: Poster: Adversarial Examples for Classifiers in High-Dimensional Network Data.\nYear: 2017\n\nAbstract: Many machine learning methods make assumptions about the data, such as, data stationarity and data independence, for an efficient learning process that requires less data. However, these assumptions may give rise to vulnerabilities if violated by smart adversaries. In this paper, we propose a novel algorithm to craft the input samples by modifying a certain fraction of input features as small as in order to bypass the decision boundary of widely used binary classifiers using Support Vector Machine (SVM). We show that our algorithm can reliably produce adversarial samples which are misclassified with 98% success rate while modifying 22% of the input features on average. Our goal is to evaluate the robustness of classification algorithms for high demensional network data by intentionally performing evasion attacks with carefully designed adversarial examples. The proposed algorithm is evaluated using real network traffic datasets (CAIDA 2007 and CAIDA 2016).","Title: Mitigating DNS query-based DDoS attacks with machine learning on software-defined networking.\nYear: 2017\n\nAbstract: Securing Internet of Things is a challenge because of its multiple points of vulnerability. In particular, Distributed Denial of Service (DDoS) attacks on IoT devices pose a major security challenge to be addressed. In this paper, we propose a DNS query-based DDoS attack mitigation system using Software-Defined Networking (SDN) to block the network traffic for DDoS attacks. With some features provided by SDN, we can analyze traffic patterns and filter suspicious network flows out. To show the feasibility of the proposed system, we particularly implemented a prototype with Dirichlet process mixture model to distinguish benign traffic from malicious traffic and conducted experiments with the dataset collected from real network traces. We demonstrate the effectiveness of the proposed method by both simulations and experiment data obtained from the real network traffic traces.","Title: Cryptanalysis of an authentication scheme for multi-gateway wireless sensor networks\nYear: 2017\n\nAbstract: Wireless sensor network has wide potential application in many fields such as military, agricultural and healthcare. However, it also has some vulnerabilities because of its openness. For this reason, many researchers have proposed various user authentication schemes for added security of wireless sensor networks. Recently, Wu et al. proposed an authentication scheme for multi-gateway wireless sensor networks in Internet of Things deployment. Wu et al. claimed that their scheme is secure against user forgery attack and session key leakage. However, we found that the scheme is vulnerable to outsider and user impersonation attacks. In this paper, we revisit Wu et al.'s scheme and analyze its vulnerabilities.","Title: Interface to Network Security Functions for Cloud-Based Security Services.\nYear: 2018\n\nAbstract: Network functions virtualization and cloud-based security services will become increasingly common in enterprise network systems to reduce the system operation costs and take advantage of the diverse network security functions (NSFs) developed by multiple vendors. In such a network environment, standardizing the interfaces to the NSFs of different vendors is essential to simplify the management of...","Title: No Silk Road for Online Gamers!: Using Social Network Analysis to Unveil Black Markets in Online Games.\nYear: 2018\n\nAbstract: Online game involves a very large number of users who are interconnected and interact with each other via the Internet. We studied the characteristics of exchanging virtual goods with real money through the processes called \"real money trading (RMT)\". This exchange might influence online game user behaviors and cause damage to the reputation of game companies. We examined in-game transactions to reveal RMT by constructing a social graph of virtual goods exchanges in an online game and identifying network communities of users.\n\n We analyzed approximately 6,000,000 transactions in a popular online game and inferred RMT transactions by comparing the RMT transactions crawled from an out-game market. Our findings are summarized as follows: (1) the size of the RMT market could be approximately estimated; (2) professional RMT providers typically form a specific network structure (either star-shape or chain) in the trading network, which can be used as a clue for tracing RMT transactions; and (3) the observed RMT market has evolved over time into a monopolized market with a small number of large-sized virtual goods providers.","Title: User Credential Cloning Attacks in Android Applications: Exploiting Automatic Login on Android Apps and Mitigating Strategies.\nYear: 2018\n\nAbstract: Automatic login is a commonly used feature of smartphones, because their small keyboards make it difficult to key in user credential information. However, this feature may pose a serious risk to smartphone users? privacy. The stored data for automatic login could be stolen by an attacker, resulting in identity theft. In this article, we demonstrate an execution of this attack in a systematic manne...","Title: A Framework for Managing User-defined Security Policies to Support Network Security Functions\nYear: 2018\n\nAbstract: Network Functions Virtualization (NFV) and Software Defined Networking (SDN) make it easier for security administrators to manage security policies on a network system. However, it is still challenging to map high-level security policies defined by users into low-level security policies that can be applied to network security devices. To address this problem, we introduce a framework for effectively managing user-defined security policies for network security functions based on standard interfaces that are currently being standardized in an IETF working group. To show the feasibility of the proposed framework, we implemented a prototype based on the RESTCONF protocol and showed that the proposed framework can be applied in real-world scenarios for network separation, DDoS mitigation and ransomeware prevention.","Title: Secure and DoS-Resilient Fragment Authentication in CCN-Based Vehicular Networks.\nYear: 2018\n\nAbstract: Content-Centric Networking (CCN) is considered as a promising alternative to traditional IP-based networking for vehicle-to-everything communication environments. In general, CCN packets must be fragmented and reassembled based on the Maximum Transmission Unit (MTU) size of the content delivery path. It is thus challenging to securely protect fragmented packets against attackers who intentionally inject malicious fragments to disrupt normal services on CCN-based vehicular networks. This paper presents a new secure content fragmentation method that is resistant to Denial-of-Service (DoS) attacks in CCN-based vehicular networks. Our approach guarantees the authenticity of each fragment through the immediate fragment verification at interim nodes on the routing path. Our experiment results demonstrate that the proposed approach provides much stronger security than the existing approach named FIGOA, without imposing a significant overhead in the process. The proposed method achieves a high immediate verification probability of 98.2% on average, which is 52% higher than that of FIGOA, while requiring only 14% more fragments than FIGOA.","Title: POSTER: I Can't Hear This Because I Am Human: A Novel Design of Audio CAPTCHA System.\nYear: 2018\n\nAbstract: A CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) provides the first line of defense to protect websites against bots and automatic crawling. Recently, audio-based CAPTCHA systems are started to use for visually impaired people in many internet services. However, with the recent improvement of speech recognition and machine learning system, audio CAPTCHAs have come to struggle to distinguish machines from users, and this situation will likely continue to worsen. Unlike conventional CAPTCHA systems, we propose a new conceptual audio CAPTCHA system, combining certain sound, which is only understandable by a machine. Our experiment results demonstrate that the tested speech recognition systems always provide correct responses for our CAPTCHA samples while humans cannot possibly understand them. Based on this computational gap between the human and machine, we can detect bots with their correct responses, rather than their incorrect ones.","Title: POSTER: Can We Use Biometric Authentication on Cloud?: Fingerprint Authentication Using Homomorphic Encryption.\nYear: 2018\n\nAbstract: Even though biometric authentication such as fingerprint authentication is popularly used, there are few network services supporting biometric authentication because many users have serious privacy concerns about leakage of the biometric data on a server. For example, in fingerprint authentication, a user's raw fingerprint is typically stored in plaintext form. Unlike conventional text passwords, we cannot use a cryptographic hash function such as SHA-256 because it is very hard to obtain the same fingerprint features even when the exactly same finger is scanned multiple times. In this paper, we present a fingerprint authentication mechanism using the Fastest Homomorphic Encryption in the West (FHEW) library for Learning With Errors (LWE) scheme. Our implementation allows us to securely store fingerprint data on a network server using homomorphic encryption to calculate the distance between two encrypted fingerprint data without decrypting them. To show the efficiency of our implementation, we used \"NIST special database 9'' containing 4,000 fingerprint samples. Our results show that two fingerprints can be efficiently compared with about 209 seconds on average even when they are securely stored in encrypted form.","Title: POSTER: DeepCRACk: Using Deep Learning to Automatically CRack Audio CAPTCHAs.\nYear: 2018\n\nAbstract: A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a defensive mechanism designed to differentiate humans and computers to prevent unauthorized use of online services by automated attacks. They often consist of a visual or audio test that humans can perform easily but that bots cannot solve. However, with current machine learning techniques and open-source neural network architectures, it is now possible to create a self-contained system that is able to solve specific CAPTCHA types and outperform some human users. In this paper, we present a neural network that leverages Mozilla's open source implementation of Baidu's Deep Speech architecture; our model is currently able to solve the audio version of an open-source CATPCHA system (named SimpleCaptcha) with 98.8% accuracy. Our network was trained on 100,000 audio samples generated from SimpleCaptcha and can solve new SimpleCaptcha audio tests in 1.25 seconds on average (with a standard deviation of 0.065 seconds). Our implementation seems additionally promising because it does not require a powerful server to function and is robust to adversarial examples that target Deep Speech's pre-trained models.","Title: The Personal Identification Chord: A Four ButtonAuthentication System for Smartwatches.\nYear: 2018\n\nAbstract: Smartwatches support access to a wide range of private information but little is known about the security and usability of existing smartwatch screen lock mechanisms. Prior studies suggest that smartwatch authentication via standard techniques such as 4-digit PINs is challenging and error-prone. We conducted interviews to shed light on current practices, revealing that smartwatch users consider the ten-key keypad required for PIN entry to be hard to use due to its small button sizes. To address this issue, we propose the Personal Identification Chord (PIC), an authentication system based on a four-button chorded keypad that enables users to enter ten different inputs via taps to one or two larger buttons. Two studies assessing usability and security of our technique indicate PICs lead to increases in setup and (modestly) recall time, but can be entered accurately while maintaining high recall rates and may improve guessing entropy compared to PINs.","Title: CyTIME: Cyber Threat Intelligence ManagEment framework for automatically generating security rules.\nYear: 2018\n\nAbstract: It is becoming increasingly necessary for organizations to build a Cyber Threat Intelligence (CTI) platform to fight against sophisticated attacks. To reduce the risk of cyber attacks, security administrators and/or analysts can use a CTI platform to aggregate relevant threat information about adversaries, targets and vulnerabilities, analyze it and share key observations from the analysis with collaborators. In this paper, we introduce CyTIME (Cyber Threat Intelligence ManagEment framework) which is a framework for managing CTI data. CyTIME can periodically collect CTI data from external CTI data repositories via standard interfaces such as Trusted Automated Exchange of Indicator Information (TAXII). In addition, CyTIME is designed to automatically generate security rules without human intervention to mitigate discovered new cybersecurity threats in real time. To show the feasibility of CyTIME, we performed experiments to measure the time to complete the task of generating the security rule corresponding to a given CTI data. We used 1,000 different CTI files related to network attacks. Our experiment results demonstrate that CyTIME automatically generates security rules and store them into the internal database within 12.941 seconds on average (max = 13.952, standard deviation = 0.580).","Title: Efficient and Secure Biometric-Based User Authenticated Key Agreement Scheme with Anonymity.\nYear: 2018\n\nAbstract: At present, a number of users employ an authentication protocol so as to enjoy protected electronic transactions in wireless networks. In order to establish an efficient and robust the transaction system, numerous researches have been conducted relating to authentication protocols. Recently, Kaul and Awasthi presented an user authentication and key agreement scheme, arguing that their scheme is able to resist various types of attacks and preserve diverse security properties. However, this scheme possesses critical vulnerabilities. First, the scheme cannot prevent two kinds of attacks, including off-line password guessing attacks and user impersonation attacks. Second, user anonymity rule cannot be upheld. Third, session key can be compromised by an attacker. Fourth, there is high possibility that the time synchronization trouble occurs. Therefore, we suggest an upgraded version of the user authenticated key agreement method that provides enhanced security. Our security and performance analysis shows that compared, to other associated protocols, our method not only improves the security level but also ensures efficiency.","Title: Two-Thumbs-Up: Physical protection for PIN entry secure against recording attacks.\nYear: 2018\n\nAbstract: We present a new Personal Identification Number (PIN) entry method for smartphones that can be used in security-critical applications, such as smartphone banking. The proposed “Two-Thumbs-Up” (TTU) scheme is resilient against observation attacks such as shoulder-surfing and camera recording, and guides users to protect their PIN information from eavesdropping by shielding the challenge area on the touch screen. To demonstrate the feasibility of TTU, we conducted a user study for TTU, and compared it with existing authentication methods (Normal PIN, Black and White PIN, and ColorPIN) in terms of usability and security. The study results demonstrate that TTU is more secure than other PIN entry methods in the presence of an observer recording multiple authentication sessions.","Title: When Harry Met Tinder: Security Analysis of Dating Apps on Android.\nYear: 2018\n\nAbstract: As the number of smartphone users has increased, so has the popularity of dating apps such as Tinder, Hinge, Grindr and Bumbler. At the same time, however, many users have growing privacy concerns about these applications disclosing their sensitive and private information to other service providers and/or strangers. This is particularly exacerbated due to the nature of dating apps requiring access to users' personal contents such as chat messages, photos, video clips and locations. In this paper, we present an analysis of security and privacy issues in popular dating apps on Android. We carefully analyze the possibility of software vulnerabilities on the five most popular dating apps on Android through network traffic analyses and reverse engineering techniques for each dating app. Our experiment results demonstrate that user credential data can be stolen from all five applications; three apps may lead to the disclosure of user profiles, and one app may lead to the disclosure of chat messages.","Title: An Implementation and Evaluation of Progressive Authentication Using Multiple Level Pattern Locks.\nYear: 2018\n\nAbstract: This paper presents a possible implementation of progressive authentication using the Android pattern lock. Our key idea is to use one pattern for two access levels to the device; an abridged pattern is used to access generic applications and a second, extended and higher-complexity pattern is used less frequently to access more sensitive applications. We conducted a user study of 89 participants and a consecutive user survey on those participants to investigate the usability of such a pattern scheme. Data from our prototype showed that for unlocking low-security applications the median unlock times for users of the multiple pattern scheme and conventional pattern scheme were 2824 ms and 5589 ms respectively, and the distributions in the two groups differed significantly (Mann-Whitney U test, p-value less than 0.05, two-tailed). From our user survey, we did not find statistically significant differences between the two groups for their qualitative responses regarding usability and security (t-test, p-value greater than 0.05, two-tailed), but the groups did not differ by more than one satisfaction rating at 90% confidence.","Title: MEDUSA: Malware Detection Using Statistical Analysis of System's Behavior\nYear: 2018\n\nAbstract: Traditional malware detection techniques have focused on analyzing known malware samples' codes and behaviors to construct an effective database of malware signatures. In recent times, however, such techniques have inherently exposed limitations in detecting unknown malware samples and maintaining the database up-to-date, as many polymorphic and metamorphic malware samples are newly created and spread very quickly throughout the Internet. To address the limitations of existing signature-based malware scanners, we take a different view and focus on designing a novel malware detection framework, called MEDUSA (MalwarE Detection Using Statistical Analysis of system's behavior), for building a model for a system's behaviors with normal processes. Unlike traditional approaches for malware detection, MEDUSA has the potential to effectively detect unknown malware samples because it is designed to monitor a system's behavior and detect significant changes from the system's normal status. In this paper, we specifically discuss several important considerations that must be taken into account to successfully develop MEDUSA in practice.","Title: A framework for DNS naming services for Internet-of-Things devices.\nYear: 2019\n\nAbstract: This paper proposes a new naming framework for Domain Name System (DNS) Name Autoconfiguration (called DNSNA) for Internet of Things (IoT) devices in Internet Protocol (IP) version 6 (IPv6) and IP version 4 (IPv4) networks. As the number of IoT devices increases, it can be a burden for users to manually configure the DNS names of the IoT devices. We propose DNSNA to provide an efficient DNS name management for IoT devices, supporting an IoT device’s DNS name auto-generation, its DNS name auto-registration, device discovery, and service discovery. A user can easily use the registered DNS information of the IoT devices for both device discovery and service discovery through DNSNA. DNSNA uses IPv6 Neighbor Discovery (ND) protocol for IPv6 IoT devices and Dynamic Host Configuration Protocol (DHCP) for IPv4 IoT devices, respectively, in the IoT DNS name autoconfiguration. With either ND or DHCP, the IoT devices can obtain a DNS suffix and construct their DNS name. Also, through a physical-contact-based authentication of a user’s smartphone with an IoT device over Near Field Communication (NFC), an authenticated IoT device can automatically register its DNS name and the corresponding IP address into a local authoritative DNS server in a secure way. Through real experiments and analysis, it is shown that DNSNA can reduce the average number of packets by 60.8% and the accumulated packet volume by 97% in comparison with the existing DNS naming service (i.e., mDNS) for IoT devices in an IPv6 network.","Title: Statistical Application Fingerprinting for DDoS Attack Mitigation\nYear: 2019\n\nAbstract: Because of the dynamic nature of network traffic patterns, such as new traffic application arrivals or flash events, it is becoming increasingly difficult for conventional anomaly detection systems to separate various applications based on their traffic patterns. In this paper, by leveraging transport layer packet-level and flow-level features, new structures called \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">application fingerprints</italic>\n are generated, which express such features in a compact and efficient manner. Based on the generated fingerprints, we propose a novel traffic classification framework. The proposed system generates profiles of normal applications using a multi-modal probability distribution. The proposed classification framework is then extended to detect distributed denial of service attacks from the collected statistical information at flow level. To demonstrate the feasibility of the proposed system, we evaluate its performance using five real-world traffic datasets. The experiment results show that the proposed method is capable of achieving an accuracy of over 97%, whereas the misclassification rate is only 2.5%.","Title: OTR: Offline OTR messaging system under network disruption.\nYear: 2019\n\nAbstract: Providing a secure and efficient communication system under network disruption without a trusted third party remains a challenging issue. To develop a secure and efficient system in such situations, we extend the conventional Off-The-Record (OTR) protocol into a new protocol named offline OTR (O2TR). O2TR provides end-to-end security between users without requiring the assumption that they are persistently connected to each other. To show the feasibility of the proposed protocol, we implemented a prototype to support O2TR based on the Gajim XMMP instant messaging platform. Our experiments showed that O2TR can be used reliably even when the corresponding network party is temporarily broken down. Moreover, O2TR provides an efficient way to resume private sessions which is about 34% faster than the original OTR. We also proved the secrecy of O2TR using an automated verification tool called AVISPA.","Title: k -Depth Mimicry Attack to Secretly Embed Shellcode into PDF Files\nYear: 2017\n\nAbstract: This paper revisits the shellcode embedding problem for PDF files. We found that a popularly used shellcode embedding technique called reverse mimicry attack has not been shown to be effective against well-trained state-of-the-art detectors. To overcome the limitation of the reverse mimicry method against existing shellcode detectors, we extend the idea of reverse mimicry attack to a more generalized one by applying the k-depth mimicry method to PDF files. We implement a proof-of-concept tool for the k-depth mimicry attack and show its feasibility by generating shellcode-embedded PDF files to evade the best known shellcode detector (PDFrate) with three classifiers. The experimental results show that all tested classifiers failed to effectively detect the shellcode embedded by the k-depth mimicry method when k >= 20.","Title: Detecting Encrypted Traffic: A Machine Learning Approach\nYear: 2016\n\nAbstract: Detecting encrypted traffic is increasingly important for deep packet inspection (DPI) to improve the performance of intrusion detection systems. We propose a machine learning approach with several randomness tests to achieve high accuracy detection of encrypted traffic while requiring low overhead incurred by the detection procedure. To demonstrate how effective the proposed approach is, the performance of four classification methods (Naive Bayesian, Support Vector Machine, CART and AdaBoost) are explored. Our recommendation is to use CART which is not only capable of achieving an accuracy of 99.9% but also up to about 2.9 times more efficient than the second best candidate (Naive Bayesian).","Title: Design and Analysis of Push Notification-Based Malware on Android.\nYear: 2018\n\nAbstract: Establishing secret command and control (C&C) channels from attackers is important in malware design. This paper presents design and analysis of malware architecture exploiting push notification services as C&C channels. The key feature of the push notification-based malware design is remote triggering, which allows attackers to trigger and execute their malware by push notifications. The use of push notification services as covert channels makes it difficult to distinguish this type of malware from other normal applications also using the same services. We implemented a backdoor prototype on Android devices as a proof-of-concept of the push notification-based malware and evaluated its stealthiness and feasibility. Our malware implementation effectively evaded the existing malware analysis tools such as 55 antimalware scanners from VirusTotal and SandDroid. In addition, our backdoor implementation successfully cracked about 98% of all the tested unlock secrets (either PINs or unlock patterns) in 5 seconds with only a fraction (less than 0.01%) of the total power consumption of the device. Finally, we proposed several defense strategies to mitigate push notification-based malware by carefully analyzing its attack process. Our defense strategies include filtering subscription requests for push notifications from suspicious applications, providing centralized management and access control of registration tokens of applications, detecting malicious push messages by analyzing message contents and characteristic patterns demonstrated by malicious push messages, and detecting malware by analyzing the behaviors of applications after receiving push messages.","Title: Data-Driven Selection Of Security Application Frameworks During Architectural Design\nYear: 2019\n\nAbstract: The selection of application frameworks is an important aspect of architectural design. Selection often requires satisficing, that is, searching a potentially large space of design alternatives until an acceptable solution is found. There is, however, little help for architects in selecting software frameworks. In this paper we investigate the criteria used by practicing software architects in selecting security frameworks. We also propose how information associated with some of the criteria that are important to architects can be obtained manually or in an automated way from online sources such as GitHub. Our ultimate goal is to identify measures associated with these criteria that can be helpful in providing support for architects to select software frameworks.","Title: Threat Modeling and Analysis of Voice Assistant Applications.\nYear: 2018\n\nAbstract: Voice assistant is an application that helps users to interact with their devices using voice commands in a more intuitive and natural manner. Recently, many voice assistant applications have been popularly deployed on smartphones and voice-controlled smart speakers. However, the threat and security of those applications have been examined only in very few studies. In this paper, we identify potential threats to voice assistant applications and assess the risk of those threats using the STRIDE and DREAD models. Our threat modeling demonstrates that generic voice assistants can potentially have 16 security threats. To mitigate the identified threats, we also discuss several defense strategies.","Title: Digital forensic analysis of encrypted database files in instant messaging applications on Windows operating systems: Case study with KakaoTalk, NateOn and QQ messenger.\nYear: 2019\n\nAbstract: Instant messaging applications store users' personal data (e.g., user profile, chat messages, photos and video clips). Because those data typically include privacy sensitive information, most instant messaging applications are trying to protect the stored data in an encrypted form so that the authorized messaging application itself can only access the data. In this paper, we analyzed the locations and file formats of personal data files in three instant messaging applications (KakaoTalk, NateOn, and QQ) which are the most popularly used in China and South Korea. We particularly examined the encryption and decryption procedures for internal databases in those messaging applications through reverse-engineering. Our analysis results demonstrate how the database files of those instant messaging applications are stored and encrypted. Moreover, in the cases of KakaoTalk and NateOn applications, we found that their encrypted database files can successfully be recovered without requiring user password. We also found that QQ messenger stores the encryption key for the database files into an external server. This implementation may raise another privacy concern because users’ personal data can be freely accessed by the service provider without user consent.","Title: Bitcoin vs. Bitcoin Cash: Coexistence or Downfall of Bitcoin Cash?\nYear: 2019\n\nAbstract: Bitcoin has become the most popular cryptocurrency based on a peer-to-peer network. In Aug. 2017, Bitcoin was split into the original Bitcoin (BTC) and Bitcoin Cash (BCH). Since then, miners have had a choice between BTC and BCH mining because they have compatible proof-of-work algorithms. Therefore, they can freely choose which coin to mine for higher profit, where the profitability depends on both the coin price and mining difficulty. Some miners can immediately switch the coin to mine only when mining difficulty changes because the difficulty changes are more predictable than that for the coin price, and we call this behavior fickle mining. In this paper, we study the effects of fickle mining by modeling a game between two coins. To do this, we consider both fickle miners and some factions (e.g., BITMAIN for BCH mining) that stick to mining one coin to maintain that chain. In this model, we show that fickle mining leads to a Nash equilibrium in which only a faction sticking to its coin mining remains as a loyal miner to the less valued coin (e.g., BCH), where loyal miners refer to those who conduct mining even after coin mining difficulty increases. This situation would cause severe centralization, weakening the security of the coin system. To determine which equilibrium the competing coin systems (e.g., BTC vs. BCH) are moving toward, we traced the historical changes of mining power for BTC and BCH and found that BCH often lacked loyal miners until Nov. 13, 2017, when the difficulty adjustment algorithm of BCH mining was changed. However, the change in difficulty adjustment algorithm of BCH mining led to a state close to the stable coexistence of BTC and BCH. We also demonstrate that the lack of BCH loyal miners may still be reached when a fraction of miners automatically and repeatedly switches to the most profitable coin to mine (i.e., automatic mining). According to our analysis, as of Dec. 2018, loyal miners to BCH would leave if more than about 5% of the total mining capacity for BTC and BCH has engaged in the automatic mining. In addition, we analyze the recent “hash war” between Bitcoin ABC and SV, which confirms our theoretical analysis. Finally, we note that our results can be applied to any competing cryptocurrency systems in which the same hardware (e.g., ASICs or GPUs) can be used for mining. Therefore, our study brings new and important angles in competitive coin markets: a coin can intentionally weaken the security and decentralization level of the other rival coin when mining hardware is shared between them, allowing for automatic mining.","Title: CBDN: Cloud-Based Drone Navigation for Efficient Battery Charging in Drone Networks\nYear: 2019\n\nAbstract: For long-distance flying, drones often need to charge their battery at quick battery-charging machines (QCMs) because of their limited battery capacity. If a drone individually chooses a QCM without any coordination, a drone network may experience QCM congestion when multiple drones select the same QCM. This QCM congestion may lead to an increasing drone traffic delay. In order to solve this problem, we propose a cloud-based drone navigation (CBDN) system for efficient drone battery charging in drone networks. In order to achieve this goal, the CBDN gathers drone traffic information and determines efficient drone routes so as to minimize the overall QCM congestion level for drone battery charging using cloud-based management. Our key idea is to find globally coordinated drone routes so as to minimize the total traffic delay in a drone network by reducing the overall QCM congestion level. In order to demonstrate the effectiveness of the proposed system, we evaluated the performance of CBDN by simulating a drone network under various network conditions. The simulation results show that CBDN is more efficient than the existing shortest-path-based drone route planning algorithms in terms of end-to-end traffic delay and QCM average utilization.","Title: The Light Will Be with You. Always -- A Novel Continuous Mobile Authentication with the Light Sensor\nYear: 2019\n\nAbstract: Existing continuous authentication proposals tend to have two major drawbacks. First, touch-based smartphone authentication approaches typically require explicit user interactions with the smartphone to collect sufficient touch data. These approaches may provide an attacker the opportunity to steal a victim's sensitive data before the system detects the attacker's intrusion. Likewise, an attacker may disable the continuous authentication scheme itself before detection. Second, sensor-based continuous authentication approaches inherently suffer from high energy consumption due to the constant usage of multiple sensors. In this paper, we present a novel continuous authentication system that collects light sensor data from a user's smartphone and analyzes them to authenticate users using support vector machines. We focus on the possibility of collecting light sensor data from users' smartphones while they are conducting daily behaviors to develop an anomaly detection system.","Title: 80% of Block Propagation Rate is Enough -- Towards Secure and Efficient PoW-based Blockchain Consensus\nYear: 2019\n\nAbstract: Recently, Samsung released Galaxy S10 supporting the cryptowallet feature [5]. However, it is still questionable whether cryptocurrency can be popularly used for mobile payments because processing transactions in existing blockchain systems are too slow. For example, public blockchain systems such as Bitcoin [6] (7 transactions per second (TPS)) and Ethereum (15 TPS) are significantly slower than mainstream payment systems such as Visa (2,000 TPS) using a centralized database.","Title: Automated Cash Mining Attacks On Mobile Advertising Networks\nYear: 2019\n\nAbstract: Rewarded advertisements are popularly used in the mobile advertising industry. In this paper, we analyze several rewarded advertisement applications to discover security weaknesses, which allow malicious users to automatically generate in-app activities for earning cash rewards on advertisement networks; we call this attack automated cash mining. To show the risk of this attack, we implemented automated cashing attacks on four popularly used Android applications (Cash Slide, Fronto, Honey Screen and Screen Stash) with rewarded advertisements through reverse engineering and demonstrated that all the tested reward apps are vulnerable to our attack implementation.","Title: Efficient Software Implementation of Homomorphic Encryption for Addition and Multiplication Operations.\nYear: 2019\n\nAbstract: Fully homomorphic encryption enables any type of calculation on encrypted data. There are several crypto libraries that provide such fully homomorphic encryption. However, since most libraries only support single level binary circuit operations, it is required for developers to efficiently implement basic arithmetic algorithms such as addition, subtraction, multiplication, and division for their own applications. In this paper, we propose fast binary addition and multiplication algorithms to support various bit-wise operations. To show the feasibility of the proposed algorithms, we implemented the proposed algorithms for 16, 32, 48, and 64 bits integers using the TFHE library. Our experiment results demonstrate that the proposed addition operation decreases the running time by 11 to 12%, and our multiplication implementation is about 3 to 4 times faster than the non-threaded method for 16, 32, 48 and 64 bits integers.","Title: Understanding Users' Risk Perceptions about Personal Health Records Shared on Social Networking Services.\nYear: 2019\n\nAbstract: To understand users' risk perceptions about sharing their PHR on SNS, we first conducted a qualitative user study by interviewing 16 participants. Next, we conducted a large-scale online user study with 497 participants in the U.S. to validate our qualitative results from the first study. Our study results show that a majority of users do not show strong motivation of sharing PHR on SNS due to several concerns such as misuse/abuse and security issues of shared PHR. In particular, participants are highly concerned about sharing diseases and diagnostic test results than other types of PHRs (e.g., details of hospital visits and medical interviews). However, we found about 55.13% of the participants have the experiences of sharing their health-related information on SNS. Also, we learned that users' sharing behavior for disease data can be significantly influenced by the severity/type of the disease as well as preferred recipients. Based on our findings, we propose a recommendation method to automatically determine whether users' posts can be shared with everyone on SNS by analyzing the keywords frequently occurred in health-related posts. Our implementation using Random Forest achieved an F-measure of 87.4%, indicating that PHR can be restrictively shared with high accuracy, when sharing health-related posts on SNS.","Title: Decamouflage: A Framework to Detect Image-Scaling Attacks on CNN\nYear: 2021\n\nAbstract: Image-scaling is a typical operation that processes the input image before feeding it into convolutional neural network models. However, it is vulnerable to the newly revealed image-scaling attack. This work presents an image-scaling attack detection framework, Decamouflage, consisting of three independent detection methods: scaling, filtering, and steganalysis, to detect the attack through examining distinct image characteristics. Decamouflage has a pre-determined detection threshold that is generic. More precisely, as we have validated, the threshold determined from one dataset is also applicable to other different datasets. Extensive experiments show that Decamouflage achieves detection accuracy of 99.9% and 98.5% in the white-box and the black-box settings, respectively. We also measured its running time overhead on a PC with an Intel i5 CPU and 8GB RAM. The experimental results show that image-scaling attacks can be detected in milliseconds. Moreover, Decamouflage is highly robust against adaptive image-scaling attacks (e.g., attack image size variances).","Title: Towards Usable And Secure Location-Based Smartphone Authentication\nYear: 2021\n\nAbstract: The concept of using location information to unlock smartphones is widely available on Android phones. To date, however, not much research has been conducted on investigating security and usability requirements for designing such location-based authentication services. To bridge this gap, we interviewed 18 participants, studying users' perceptions and identifying key design requirements such as the need to support fine-grained indoor location registration and location (unlock coverage) size adjustment. We then conducted a field study with 29 participants and a fully-functioning application to study real-world usage behaviors. On average, the participants were able to reduce about 36% of manual unlock attempts by using our application for three weeks. 28 participants enduringly used registered locations to unlock their phones despite being able to delete them during the study and unlock manually instead. Worryingly, however, 23 participants registered at least one insecure location - defined as a location where an unwanted adversary can physically access their phones - as a trusted location mainly due to convenience or low (perceived) likelihood of phones being attacked. 52 out of 65 total registered locations were classified as insecure by the definition above. Interestingly, regardless of whether locations were considered secure or insecure, the participants preferred to select large phone unlock coverage areas.","Title: ARGH!: Automated Rumor Generation Hub\nYear: 2021\n\nAbstract: ABSTRACTIt is still challenging to effectively identify rumors due to rapid changes in people's interests and perceptions. To enhance rumor detectors, we first need to better understand which rumors are effective (in terms of bypassing detection) and their characteristics. In this paper, we introduce ARGH, a novel framework to automatically generate rumors using recent advancements in natural language processing, customized to target and generate specific topics. To show the effectiveness of ARGH, we conducted a user study with 212 participants and analyzed how well humans can detect the rumors generated by ARGH, and we also tested its performance against the state-of-the-art rumor detection model PLAN [17]. Surprisingly, the experimental results demonstrate that the generated rumors are significantly harder to identify as rumors than hand-written rumors, degrading the detection accuracy by both humans and machines by 18.87% and 17.62%, respectively. We believe that ARGH will be a useful tool to obtain high quality and evasive rumor datasets quickly, which is often a tedious and time consuming task. Further, our analysis results provide valuable insight into how to characterize evasive rumors and how they can be generated, which will help to enhance the existing rumor detection techniques.","Title: On the Robustness of Intrusion Detection Systems for Vehicles Against Adversarial Attacks\nYear: 2021\n\nAbstract: Because connected cars typically have several communication capabilities (through 5G, WiFi, and Bluetooth), and third-party applications can be installed on the cars, it would be essential to deploy intrusion detection systems (IDS) to prevent attacks from external attackers or malicious applications. Therefore, many IDS proposals have been presented to protect the controller area network (CAN) in a vehicle. Some studies showed that deep neural network models could be effectively used to detect various attacks on the CAN bus. However, it is still questionable whether such an IDS is sufficiently robust against adversarial attacks that are crafted aiming to target the IDS. In this paper, we present a genetic algorithm to generate adversarial CAN attack messages for Denial-of-Service (DoS), fuzzy, and spoofing attacks to target the state-of-the-art deep learning-based IDS for CAN. The experimental results demonstrate that the state-of-the-art IDS is not effective in detecting the generated adversarial CAN attack messages. The detection rates of the IDS were significantly decreased from 99.27%, 96.40%, and 99.63% to 2.24%, 11.59%, and 0.01% for DoS, fuzzy, and spoofing attacks, respectively.","Title: Security Evaluation of n-Choose-k-Sum PUFs Against Modeling Attacks\nYear: 2021\n\nAbstract: A physical unclonable function (PUF) generates hardware intrinsic volatile secrets by exploiting uncontrollable manufacturing randomness. Several PUF candidates use challenge-response pairs (CRPs) to enhance their security. A practically plausible idea for PUF is to use the technique called n-Choose-k-Sum (nCk) structure/topology, exemplified by the memristive device based on strong PUF (mrSPUF). The previous analysis claimed that nCk-PUF is resilient to modeling attacks. This paper provides numerical security evaluations on simulated CRPs - we first construct a mathematical model of nCk-PUF, and then analyze the possibility of modeling attacks using machine learning (ML). Our analysis demonstrates that our modeling attacks could break the unpredictability of nCk-PUF even though the non-linearity of nCk-PUF could be increased due to XOR-operations on its circuit. Our analysis demonstrates that our modeling attacks could break the unpredictability of nCk-PUF even though the non-linearity of nCk-PUF could be increased due to XOR-operations on its circuit. Consequently, our analysis suggest that n-Choose-k-Sum PUFs (including mrSPUF) sharing similar topology could be insecure. It should be careful when utilizing nCk-PUF for strong PUF applications, and it is suggested to add some security blocks to protect the challenge-response interface, such as the Lockdown-PUF with additional random number generator (RNG), TREVERSE with additional Hash."],"string":"[\n \"Title: A Perfect Collision-Free Pseudonym System\\nYear: 2011\\n\\nAbstract: For anonymous communication, the most popular method is to use pseudonyms instead of original identities. We previously demonstrated the possibility of a collision-free pseudonym system by uniquely assigning a permutation element to each network entity. We extend this idea by assigning k permutation elements to each entity for k ≥ 1. We analyse the randomness of the pseudonyms used in the proposed system to show the effect of k by varying k from 1 to 50. Our experimental results show that our pseudonym system can provide practical anonymity with k.\",\n \"Title: Efficient channel selection using hierarchical clustering\\nYear: 2012\\n\\nAbstract: Increases in the number of TV channels requires users to spend more time to select their preferred channels since the user interaction for browsing is practically limited to the conventional remote control with a two-way scrolling button. We formally define the problem to construct the optimal channel ordering which minimizes the seek distance in selecting channels and show this problem is NP-hard. In addition, we present a reasonable heuristic to solve this problem. The proposed method constructs an efficient channel ordering by applying a hierarchical clustering algorithm based on the frequencies of switching events between channels. We demonstrate the feasibility of this method by applying a number of well-known hierarchical clustering algorithms and evaluating the number of user inputs required for selecting channels. Our experimental results show that the proposed method significantly decreases the number of user inputs compared with the conventional methods.\",\n \"Title: PIN selection policies: Are they really effective?\\nYear: 2012\\n\\nAbstract: Users have conflicting sets of requirements when it comes to choosing Personal Identification Numbers (PINs) for mobile phones or other systems that use PINs for authentication: the conflict lies between the 'easy to remember' usability requirement and the 'hard to guess' security requirement. Users often ignore the security requirement and choose PINs that are easy to remember and reuse, making it also easy for attackers to guess and compromise them. Just as the password strength is controlled through various password policies, PIN selection policies may be used to help users choose stronger PINs and meet various security requirements. An example policy would not allow the use of the most commonly selected PINs. An online user study was conducted to investigate the effectiveness of such PIN selection policies, requesting the participants to choose PINs under some carefully designed policies. The participants were also asked to record the memorability (remembrance difficulty) score of each PIN, indicating how easy/hard it was to remember the selected PIN. Based on the entropies calculated on the collected PINs and their memorability scores, this paper demonstrates that restricting some number of commonly used PINs (e.g. restricting the 200 most commonly used ones) is beneficial: this type of policy would significantly increase the randomness of PINs without incurring significant memorability overhead. Our results also showed that any PIN- or PIN-pattern-based blacklisting policy should be constructed with caution since the total PIN space may become too small, making it easier for attackers to guess PINs.\",\n \"Title: Scalable DRM system for media portability\\nYear: 2007\\n\\nAbstract: We present a new digital rights management (DRM) system for media portability using dynamic multimedia adaptation. For a user to share multimedia resources over home network, several DRM technologies based on the domain have been introduced. Domain-based approaches enable users to access contents on multiple devices within the same domain. However, most of current DRM systems were only designed for a homogeneous environment where common AV profiles are supported. It is a challenge to share the domain contents between domain members with diverse capabilities while ensuring the protection of the intellectual property rights for the legally obtained contents. In this paper, we propose an architecture that enables DRM contents to be securely shared between various home devices in a seamless manner.\",\n \"Title: RAD: Recipient-anonymous data delivery based on public routing proxies\\nYear: 2011\\n\\nAbstract: This paper presents a Recipient-Anonymous DataDelivery (RAD), tailored and optimized for stable-topology networks. There is one simplistic approach for achieving recipient anonymity. If a message is equally broadcasted to all network entities (e.g., routers and hosts), an adversary cannot infer any traffic patterns for the intended recipient. While this technique is unconditionally secure, no one believes that this is a practical solution except in some special network environments since it requires extremely expensive traffic overhead. In this paper we realize this idea with an efficient multicast protocol by introducing the concept of a public routing proxy. A public routing proxy enables a sender to deliver a message to the intended recipient anonymously since the public routing proxy multicasts the message to a set of k network entities including the intended recipient. Thus, in the proposed protocol, the recipient's k-anonymity can be unconditionally guaranteed. We also demonstrate the practicality of the proposed protocol through intensive simulation based on well-known network topologies.\",\n \"Title: A spatial cloaking framework based on range search for nearest neighbor search\\nYear: 2009\\n\\nAbstract: For nearest neighbor search, a user queries a server for nearby points of interest (POIs) with his/her location information. Our aim is to protect the user's sensitive information against adversaries including the location-based service itself. Most research efforts have elaborated on reasonable trade-offs between privacy and utility. We propose a framework based on range search query without a trusted middleware. We design a query processing algorithm for the minimum set of candidate POIs by computing the local Voronoi diagram relevant to the cloaked region. Contrary to common belief that cloaking approaches using range search incur expensive processing and communication cost, the experimental results show that the framework incurs reasonable processing and communication overhead even for large cloaked regions.\",\n \"Title: Achieving attestation with less effort: an indirect and configurable approach to integrity reporting\\nYear: 2011\\n\\nAbstract: This paper proposes an indirect attestation paradigm for verifying the trustworthiness of end user platforms. This approach overcomes several criticisms of attestation by maintaining the user's freedom to choose their own software configurations and minimising the whitelist management overhead for the relying party. Each user platform defines its own acceptable software combination in terms of reference integrity measurements, and reports the local verification results to the relying party through a late-launched, trusted Platform Trust Service. The relying party simply checks this verification result and a security meta-policy that has been used to ensure the quality of the security checks performed locally. The Platform Trust Service is also responsible for reporting whether this meta-policy is satisfied. By configuring the meta-policy, the relying party selects an indirect attestation paradigm that best meets their high-level security requirements.\",\n \"Title: Self-authorized public key management for home networks\\nYear: 2007\\n\\nAbstract: This paper describes the key management method which allows secure communication channels between devices in home networks. Home network technologies have developed to enable various kinds of home devices to access the digital information between the devices. Without security framework, however, the digital information including a user's private data may be exposed to a malicious attacker. Although conventional public key cryptosystems generally provide security features such as confidentiality and integrity, the distribution of the keys is vulnerable to man-in-the-middle attack without a trusted third party. In general home networks are dynamically set up without relying on any pre-existing infrastructure or central administration. Therefore, we must implement key distribution schemes without the assumption of a trusted third party. In this paper, we present self-authorized public key management for home networks. Our idea is to bind the device owner's authorization information to the public key of a device. Our protocol enables the distribution of the authenticated public key using an identity-based encryption scheme. We also provide heuristic analysis of various security properties.\",\n \"Title: Centrality prediction in dynamic human contact networks\\nYear: 2012\\n\\nAbstract: Real technological, social and biological networks evolve over time. Predicting their future topology has applications to epidemiology, targeted marketing, network reliability and routing in ad hoc and peer-to-peer networks. The key problem for such applications is usually to identify the nodes that will be in more important positions in the future. Previous researchers had used ad hoc prediction functions. In this paper, we evaluate ways of predicting a node's future importance under three important metrics, namely degree, closeness centrality, and betweenness centrality, using empirical data on human contact networks collected using mobile devices. We find that node importance is highly predictable due to both periodic and legacy effects of human social behaviour, and we design reasonable prediction functions. However human behaviour is not the same in all circumstances: the centrality of students at Cambridge is best correlated both daily and hourly, no doubt due to hourly lecture schedules, while academics at conferences exhibit rather flat closeness centrality, no doubt because conference attendees are generally trying to speak to new people at each break. This highlights the utility of having a number of different metrics for centrality in dynamic networks, so as to identify typical patterns and predict behaviour. We show that the best-performing prediction functions are 25% more accurate on average than simply using the previous centrality value. These prediction functions can be efficiently computed in linear time, and are thus practical for processing dynamic networks in real-time.\",\n \"Title: Hybrid spam filtering for mobile communication\\nYear: 2009\\n\\nAbstract: Spam messages are an increasing threat to mobile communication. Several mitigation techniques have been proposed, including white and black listing, challenge-response and content-based filtering. However, none are perfect and it makes sense to use a combination rather than just one. We propose an anti-spam framework based on the hybrid of content-based filtering and challenge-response. A message, that has been classified as uncertain through content-based filtering, is checked further by sending a challenge to the message sender. An automated spam generator is unlikely to send back a correct response, in which case, the message is classified as spam. Our simulation results show the trade-off between the accuracy of anti-spam classifiers and the incurring traffic overhead, and demonstrate that our hybrid framework is capable of achieving high accuracy regardless of the content-based filtering algorithm being used.\",\n \"Title: Effective measurement selection in truncated kernel density estimator: Voronoi mean shift algorithm for truncated kernels\\nYear: 2011\\n\\nAbstract: The Gating/Truncation technique is adapted to choose relatively significant measurements rather than all measurements to speed up mean shift algorithm which is one of the well-known clustering algorithms in the field of computer vision. The conventional mean shift algorithm can be sensitive to selecting measurements since the measurements are truncated with a Gaussian window of a fixed size. In particular when a small gating window is selected, it cannot properly cluster data points located far from major clusters and thus it generates unwanted, small clusters. We present a robust gating technique for truncated mean shift algorithm based on a geometric structure called Voronoi diagram of a given data set. Unlike conventional gating/truncation techniques our proposed truncation technique can provide nonlinear truncation windows with variable sizes constructed by using the Voronoi diagram to effectively identify outlier points in clusters. We also demonstrate the feasibility of this technique by applying it on synthetic and real-world image data sets. The experimental results show that the proposed truncation technique provides a more robust clustering result compared to the conventional truncation techniques. The proposed algorithm can be effectively applied to denoising of images by removing background noise.\",\n \"Title: Finding influential neighbors to maximize information diffusion in twitter\\nYear: 2014\\n\\nAbstract: The problem of spreading information is a topic of considerable recent interest, but the traditional influence maximization problem is inadequate for a typical viral marketer who cannot access the entire network topology. To fix this flawed assumption that the marketer can control any arbitrary k nodes in a network, we have developed a decentralized version of the influential maximization problem by influencing k neighbors rather than arbitrary users in the entire network. We present several reasonable neighbor selection schemes and evaluate their performance with a real dataset collected from Twitter. Unlike previous studies using network topology alone or synthetic parameters, we use real propagation rate for each node calculated from the Twitter messages during the 2010 UK election campaign. Our experimental results show that information can be efficiently propagated in online social networks using neighbors with a high propagation rate rather than those with a high number of neighbors.\",\n \"Title: How to Compare the Scientific Contributions between Research Groups\\nYear: 2009\\n\\nAbstract: We present a method to analyse the scientific contributions between research\\ngroups. Given multiple research groups, we construct their journal/proceeding\\ngraphs and then compute the similarity/gap between them using network analysis.\\nThis analysis can be used for measuring similarity/gap of the topics/qualities\\nbetween research groups' scientific contributions. We demonstrate the\\npracticality of our method by comparing the scientific contributions by Korean\\nresearchers with those by the global researchers for information security in\\n2006 - 2008. The empirical analysis shows that the current security research in\\nSouth Korea has been isolated from the global research trend.\",\n \"Title: Don't count the number of friends when you are spreading information in social networks\\nYear: 2014\\n\\nAbstract: The problem of spreading information in social networks is a topic of considerable recent interest, but the conventional influence maximisation problem which selects a set of any arbitrary k nodes in a network as the initially activated nodes might be inadequate in a real-world social network -- cyber-stalkers try to initially spread a rumour through their neighbours only rather than arbitrary users selected from the entire network. To consider this more practical scenario, Kim and Eiko [16] introduced the optimisation problem to find influential neighbours to maximise information diffusion. We extend this model by introducing several important parameters such as user propagation rate on his (or her) neighbours to provide a more general and practical information diffusion model. We performed intensive simulations on several real-world network topologies (emails, blogs, Twitter and Facebook) to develop more effective information spreading schemes under this model. Unlike the results of previous research, our experimental results shows that information can be efficiently propagated in social networks using the propagation rate alone, even without consideration of the \\\"number of friends\\\" information. Moreover, we found that the naive random spreading would be used to efficiently spread information if k increases sufficiently (e.g. k = 4).\",\n \"Title: We Are Still Vulnerable to Clickjacking Attacks: About 99ä% of Korean Websites Are Dangerous\\nYear: 2013\\n\\nAbstract: Clickjacking is an attack that tricks victims into clicking on invisible elements of a web page to perform an unintended action that is advantageous for an attacker. To defend against clickjacking, many techniques have already been proposed, but it is still unclear whether they are effectively deployed in practice. We study how vulnerable Korean websites are to clickjacking attacks by performing real attacks on top 100 popular Korean websites as well as all the financial websites. Our results are quite significant: almost all Korean websites (about 99.2ä%) that we looked at are vulnerable to clickjacking attacks. Extending our observation to mobile websites, we can also obtain similar results.\",\n \"Title: Influential Neighbours Selection for Information Diffusion in Online Social Networks\\nYear: 2012\\n\\nAbstract: The problem of maximizing information diffusion through a network is a topic of considerable recent interest. A conventional problem is to select a set of any arbitrary k nodes as the initial influenced nodes so that they can effectively disseminate the information to the rest of the network. However, this model is usually unrealistic in online social networks since we cannot typically choose arbitrary nodes in the network as the initial influenced nodes. From the point of view of an individual user who wants to spread information as much as possible, a more reasonable model is to try to initially share the information with only some of its neighbours rather than a set of any arbitrary nodes; but how can these neighbours be effectively chosen? We empirically study how to design more effective neighbours selection strategies to maximize information diffusion. Our experimental results through intensive simulation on several real- world network topologies show that an effective neighbours selection strategy is to use node degree information for short-term propagation while a naive random selection is also adequate for long-term propagation to cover more than half of a network. We also discuss the effects of the number of initial activated neighbours. If we particularly select the highest degree nodes as initial activated neighbours, the number of initial activated neighbours is not an important factor at least for long-term propagation of information.\",\n \"Title: Network analysis of temporal trends in scholarly research productivity.\\nYear: 2012\\n\\nAbstract: We propose a method to identify the journals or proceedings that are most highly esteemed by a research group over some time frame. Using open publication databases, we identify the experts in the community, and analyse their publication pattern, and then use this as a guideline for evaluating scientific outputs of other groups of researchers publishing in the same domain. To illustrate the practicality of our method, we analyse the scientific output of Korean researchers in the security subject domain from 2004 to 2009, and comparing this groups' output with that of well-known researchers. Our empirical analysis demonstrates that there is a persistent gap between these two research groups' publications impact over this period, although the absolute number of journal publications greatly increased over recent years. (C) 2011 Elsevier Ltd. All rights reserved.\",\n \"Title: What's in Twitter: I Know What Parties are Popular and Who You are Supporting Now!\\nYear: 2013\\n\\nAbstract: In modern politics, parties and individual candidates must have an online presence and usually have dedicated social media coordinators. In this context, we study the usefulness of analysing Twitter messages to identify both the characteristics of political parties and the political leaning of users. As a case study, we collected the main stream of Twitter related to the 2010 UK General Election during the associated period -- gathering around 1,150,000 messages from about 220,000 users. We examined the characteristics of the three main parties in the election and highlighted the main differences between parties. First, Lab our members were the most active and influential during the election while Conservative members were the most organized to promote their activities. Second, the websites and blogs that each political party's members supported are clearly different from those that all the other political parties' members supported. From these observations, we develop a simple and practical classification method which uses the number of Twitter messages referring to a particular political party. The experimental results showed that the proposed classification method achieved about 86% classification accuracy and outperforms other classification methods that require expensive costs for tuning classifier parameters and/or knowledge about network topology.\",\n \"Title: Privacy-enhanced public view for social graphs\\nYear: 2009\\n\\nAbstract: We consider the problem of releasing a limited public view of a sensitive graph which reveals at least k edges per node. We are motivated by Facebook's public search listings, which expose user profiles to search engines along with a fixed number of each user's friends. If this public view is produced by uniform random sampling, an adversary can accurately approximate many sensitive features of the original graph, including the degree of individual nodes. We propose several schemes to produce public views which hide degree information. We demonstrate the practicality of our schemes using real data and show that it is possible to mitigate inference of degree while still providing useful public views.\",\n \"Title: Privacy-Enhancing Queries In Personalized Search With Untrusted Service Providers\\nYear: 2012\\n\\nAbstract: For personalized search, a user must provide her personal information. However, this sometimes includes the user's sensitive information about individuals such as health condition and private lifestyle. It is not sufficient just to protect the communication channel between user and service provider. Unfortunately, the collected personal data can potentially be misused for the service providers' commercial advantage (e.g. for advertising methods to target potential consumers). Our aim here is to protect user privacy by filtering out the sensitive information exposed from a user's. query input at the system level. We propose a framework by introducing the concept of query generalizer. Query generalizer is a middleware that takes a query for personalized search, modifies the query to hide user's sensitive personal information adaptively depending on the user's privacy policy, and then forwards the modified query to the service provider. Our experimental results show that the best-performing query generalization method is capable of achieving a low traffic overhead within a reasonable range of user privacy. The increased traffic overhead varied from 1.0 to 3.3 times compared to the original query.\",\n \"Title: A new collision-free pseudonym scheme in mobile ad hoc networks\\nYear: 2009\\n\\nAbstract: A mobile ad hoc network (MANET) is a decentralized network of mobile nodes. Due to the broadcast nature of radio transmissions, communication in MANETs is more susceptible to malicious traffic analysis. An interesting problem is how to thwart malicious traffic analysis. Most anonymous communication protocols are based on the pseudonyms of mobile nodes. However, conventional pseudonym schemes have some limitations such as collisions of pseudonyms and high computational complexity due to the use of cryptographic hash functions. Collisions of identities are not desirable since they are the main causes for reduced effective bandwidth, increased energy consumption and non-deterministic data delivery. In this paper, we propose a new collision-free pseudonym scheme to enable anonymous communication. In our approach, each node generates pseudonyms by using a permutation matrix without collisions. The challenging issue is how to store the overall permutation matrix. It is practically hard to assume that mobile nodes maintain the permutation matrix due to the limitation of resources. Therefore we design the online computation of each node's own pseudonym without loading the overall matrix.\",\n \"Title: Phishing detection with popular search engines: simple and effective\\nYear: 2011\\n\\nAbstract: We propose a new phishing detection heuristic based on the search results returned from popular web search engines such as Google, Bing and Yahoo. The full URL of a website a user intends to access is used as the search string, and the number of results returned and ranking of the website are used for classification. Most of the time, legitimate websites get back large number of results and are ranked first, whereas phishing websites get back no result and/or are not ranked at all. To demonstrate the effectiveness of our approach, we experimented with four well-known classification algorithms --- Linear Discriminant Analysis, Naïve Bayesian, K -Nearest Neighbour, and Support Vector Machine --- and observed their performance. The K -Nearest Neighbour algorithm performed best, achieving true positive rate of 98% and false positive and false negative rates of 2%. We used new legitimate websites and phishing websites as our dataset to show that our approach works well even on newly launched websites/webpages --- such websites are often misclassified in existing blacklisting and whitelisting approaches.\",\n \"Title: An Experimental Evaluation of Robustness of Networks\\nYear: 2013\\n\\nAbstract: Models of conflict in networks provide insights into applications ranging from epidemiology to guerilla warfare. Barabási, Albert, and Jeong modeled selective attacks on networks in which an attacker targets high-order nodes to destroy connectivity; Nagaraja and Anderson extended this to iterated attacks where the attacker and defender take turns removing and rebuilding nodes and edges according to given strategies. We extend the iterative model by introducing the cost required to perform network operations. This gives a much finer granularity than previous models, whether we are interested in network resilience against random failures or intentional attacks. We empirically study how to design more effective attacks and/or defenses through intensive simulation on several well-known network topologies, including the three real-world networks. In particular, an effective defense against many attacks is to add new links connecting low-centrality nodes to maintain the overall balance of network centrality.\",\n \"Title: On the Effectiveness of Pattern Lock Strength Meters: Measuring the Strength of Real World Pattern Locks\\nYear: 2015\\n\\nAbstract: We propose an effective pattern lock strength meter to help users choose stronger pattern locks on Android devices. To evaluate the effectiveness of the proposed meter with a real world dataset (i.e., with complete ecological validity), we created an Android application called EnCloud that allows users to encrypt their Dropbox files. 101 pattern locks generated by real EnCloud users were collected and analyzed, where some portion of the users were provided with the meter support. Our statistical analysis indicates that about 10% of the pattern locks that were generated without the meter support could be compromised through just 16 guessing attempts. As for the pattern locks that were generated with the meter support, that number goes up to 48 guessing attempts, showing significant improvement in security. Our recommendation is to implement a strength meter in the next version of Android.\",\n \"Title: Visualizing Privacy Risks Of Mobile Applications Through A Privacy Meter\\nYear: 2015\\n\\nAbstract: When it comes to installing mobile applications on Android devices, users tend to ignore privacy warning messages about permissions being requested. Warning messages are often shown too late and are hard to interpret for normal users. To improve users' awareness of potential privacy implications of installing an application, we designed a \\\"privacy meter\\\" that visualizes the risks (in a slider bar format) imposed by the types of permissions being requested. Interpreting and understanding privacy risks become quick and easy.Our lab study shows that the privacy meter is the most effective solution compared to Google's existing permission screens and privacy fact feature. With the privacy meter in place, only about 26% of participants recommended applications that have high privacy risks to their friends and family members. That is a significant improvement from the 61% of participants who recommended high risk applications when Google's permission screens were used. The time taken to make recommendation decisions, on average, also dropped from 72 seconds to 26 seconds when the privacy meter was used.\",\n \"Title: A Framework for Security Services Based on Software-Defined Networking\\nYear: 2015\\n\\nAbstract: This paper proposes a framework for security services using Software-Defined Networking (SDN) and specifies requirements for such a framework. It describes two representative security services, such as (i) centralized firewall system and (ii) centralized DDoS-attack mitigation system. For each service, this paper discusses the limitations of legacy systems and presents a possible SDN-based system to protect network resources by controlling suspicious and dangerous network traffic that can be regarded as security attacks.\",\n \"Title: SBUS: Smart e-Bus Battery Substitution Scheme in Vehicular Networks\\nYear: 2015\\n\\nAbstract: This paper proposes a Smart e-Bus Battery Substitution Scheme (called SBUS), tailored and optimized for the commute service of e-Buses using a cloud-based management system. To the best of our knowledge, our scheme is the first attempt to investigate the efficient battery replacement of e-Buses in road networks, based on the trajectories (i.e., Travel routes) of e-Buses in road networks. Through simulations, it is shown that our SBUS scheme outperforms baselines in a road network with multiple bus lines.\",\n \"Title: A Survey on Interfaces to Network Security Functions in Network Virtualization\\nYear: 2015\\n\\nAbstract: Network Functions Virtualization (NFV) opens new opportunities and challenges for security community. Unlike existing physical network infrastructure, in a virtualized network platform, security services can be dynamically deployed and maintained to cope with the threat of sophisticated network attacks that are increasing over time. This paper surveys the activity that many security vendors and Internet service providers are trying to define common interfaces for NFV-based security services through the analysis of use cases and related technologies. This activity is currently lead by Internet Engineering Task Force (IETF) that is an international Internet standardization organization.\",\n \"Title: Privacy Preserving Nearest Neighbor Search Based on Topologies in Cellular Networks\\nYear: 2015\\n\\nAbstract: As the popularity of location-based services (LBSes) is increasing, the location privacy has become a main concern. Among the rich collection of location privacy techniques, the spatial cloaking is one of the most popular techniques. In this paper, we propose a new spatial cloaking technique to hide a user's location under a cloaking of the serving base station (SeNB) and anonymize SeNB with a group of dummy locations in the neighboring group of another base station as central eNB (CeNB). Unlike the most existing approaches for selecting a dummy location, such as the center of a virtual circle, we select a properly chosen dummy location from real locations of eNBs to minimize side information for an adversary. Our experimental results show that the proposed scheme can achieve a reasonable degree of accuracy (>96%) for nearest neighbor services while providing a high level of location privacy.\",\n \"Title: KaaSP: keying as a service provider for small and medium enterprises using untrusted cloud services\\nYear: 2014\\n\\nAbstract: Cloud computing provides a framework for allowing remote and nearly instantaneous access to data and resources from any location in the world with an Internet connection. However, it faces privacy concerns since cloud service providers can also access user data on their storage. Although several encryption services and applications were introduced for personal users, it is still questionable whether such services can effectively be deployed for enterprises due to their lack of scalability. We propose a new access control system that incorporates encryption, based on access via a third-party key management service. The proposed system introduces a new entity named a Keying as a Service Provider (KaaSP) to more securely provide a data encryption service. In our approach, data encryption keys are generated through a negotiation with the KaaSP which would not have access to all key parts. Therefore, even if petitioned by a powerful adversary such as a law enforcement organization or breached by an attack, the data could not be leaked. Moreover, user data on the cloud storage can be protected from access attempts made by a lost device controlled by an unauthorized user since a lost device's credential for authentication can instantly be revoked. Additionally, the controlling organization can seamlessly edit access credentials via this cryptographic framework.\",\n \"Title: Analyzing Unnecessary Permissions Requested By Android Apps Based On Users' Opinions\\nYear: 2014\\n\\nAbstract: Many existing mobile apps request for unnecessary permissions knowing that users often ignore permission warning messages. We conducted an online user study to investigate how users feel about permissions being requested by both free and paid Android apps. Results show that users tend to feel that free Android apps request for more unnecessary permissions compared to paid apps. Users also felt that older apps (those that are previously released and have gone through several updates) request for more unnecessary permissions than those that are newly released. Based on that observation, we surmise that many developers initially publish apps that require a small set of permissions (so that users are not discouraged from installing an app), and gradually add more permissions to their apps through updates.\",\n \"Title: Enhancing Conformance Testing Using Symbolic Execution for Network Protocols\\nYear: 2015\\n\\nAbstract: Security protocols are notoriously difficult to get right, and most go through several iterations before their hidden security vulnerabilities, which are hard to detect, are triggered. To help protocol designers and developers efficiently find non-trivial bugs, we introduce SYMCONF, a practical conformance testing tool that generates high-coverage test input packets using a conformance test suite and symbolic execution. Our approach can be viewed as the combination of conformance testing and symbolic execution: 1) it first selects symbolic inputs from an existing conformance test suite; 2) it then symbolically executes a network protocol implementation with the symbolic inputs; and 3) it finally generates high-coverage test input packets using a conformance test suite. We demonstrate the feasibility of this methodology by applying SYMCONF to the generation of a stream of high quality test input packets for multiple implementations of two network protocols, the Kerberos Telnet protocol and Dynamic Host Configuration Protocol (DHCP), and discovering non-trivial security bugs in the protocols.\",\n \"Title: A Healthcare Information System For Secure Delivery And Remote Management Of Medical Records\\nYear: 2016\\n\\nAbstract: With the rapid merger of healthcare business and information technology, more healthcare institutions and medical practices are sharing information. Since these records often contain patients' sensitive personal information, Healthcare Information Systems (HISs) should be properly designed to manage these records in a secure manner. We propose a novel security design for the HIS complying with the security and privacy rules. The proposed system defines protocols to ensure secure delivery of medical records over insecure public networks and reliable management of medical record in the remote server without incurring excessive costs to implement services for security. We demonstrate the practicality of the proposed system through a security analysis and performance evaluation.\",\n \"Title: Keyboard or keylogger?: A security analysis of third-party keyboards on Android\\nYear: 2015\\n\\nAbstract: Use of third-party keyboards makes Android more flexible and customizable. However, we demonstrate their potential security risks by implementing a proof-of-concept keylogger that can effectively steal users' sensitive keystrokes with 81 popular websites (out of 100 tested websites). We also empirically analyzed the security behaviors of 139 keyboard applications that were available on Google Play. Our study results show that the majority of existing keyboard applications (84 out of 139) could be potentially misused as malicious keyloggers. To avoid such keylogging attacks, we discuss possible defense mechanisms.\",\n \"Title: Devil in a box: Installing backdoors in electronic door locks\\nYear: 2015\\n\\nAbstract: Electronic door locks must be carefully designed to allow valid users to open (or close) a door and prevent unauthorized people from opening (or closing) the door. However, lock manufacturers have often ignored the fact that door locks can be modified by attackers in the real world. In this paper, we demonstrate that the most popular electronic door locks can easily be compromised by inserting a malicious hardware backdoor to perform unauthorized operations on the door locks. Attackers can replay a valid DC voltage pulse to open (or close) the door in an unauthorized manner or capture the user's personal identification number (PIN) used for the door lock.\",\n \"Title: Surpass: System-initiated User-replaceable Passwords\\nYear: 2015\\n\\nAbstract: System-generated random passwords have maximum password security and are highly resistant to guessing attacks. However, few systems use such passwords because they are difficult to remember. In this paper, we propose a system-initiated password scheme called \\\\\\\"Surpass\\\\\\\" that lets users replace few characters in a random password to make it more memorable. We conducted a large-scale online study to evaluate the usability and security of four Surpass policies, varying the number of character replacements allowed from 1 to 4 in randomly-generated 8-character passwords. The study results suggest that some Surpass policies (with 3 and 4 character replacements) outperform by 11% to 13% the original randomly-generated password policy in memorability, while showing a small increase in the percentage of cracked passwords. When compared to a user-generated password complexity policy (that mandates the use of numbers, symbols, and uppercase letters) the Surpass policy with 4-character replacements did not show statistically significant inferiority in memorability. Our qualitative lab study showed similar trends. This Surpass policy demonstrated significant superiority in security though, with 21% fewer cracked passwords than the user-generated password policy.\",\n \"Title: An Empirical Study of Click Fraud in Mobile Advertising Networks\\nYear: 2015\\n\\nAbstract: Smartphone advertisement is increasingly used among many applications and allows developers to obtain revenue through in-app advertising. Our study aims at identifying potential security risks of a type of mobile advertisement where advertisers are charged for their advertisements only when a user clicks (or touches) on the advertisements in their applications. In the Android platform, we design an automated click generation attack and empirically evaluate eight popular advertising networks by performing real attacks on them. Our experimental results show that six advertising networks (75%) out of eight (Millennial Media, App Lovin, Ad Fit, Mdot M, Rev Mob and Cauly Ads) are vulnerable to our attacks. We also discuss how to develop effective defense mechanisms to mitigate such automated click fraud attacks.\",\n \"Title: Visual Honey Encryption: Application to Steganography\\nYear: 2015\\n\\nAbstract: Honey encryption (HE) is a new technique to overcome the weakness of conventional password-based encryption (PBE). However, conventional honey encryption still has the limitation that it works only for binary bit streams or integer sequences because it uses a fixed distribution-transforming encoder (DTE). In this paper, we propose a variant of honey encryption called visual honey encryption which employs an adaptive DTE in a Bayesian framework so that the proposed approach can be applied to more complex domains including images and videos. We applied this method to create a new steganography scheme which significantly improves the security level of traditional steganography.\",\n \"Title: Bypassing the Integrity Checking of Rights Objects in OMA DRM: a Case Study with the MelOn Music Service\\nYear: 2016\\n\\nAbstract: Commercial digital music is typically distributed in the music source market via Digital Rights Management systems (DRM). DRM systems help remotely control the music contents. The Open Mobile Alliance (OMA) DRM became the de facto standard after major market adoption because of its support for a wide variety of different business and usage models. In OMA DRM, a popular business model is a (monthly) subscription enforced by controlling the period of playback time; once the given period of time expires, the music cannot be played. In this paper, we demonstrate how to bypass the integrity checking of the rights object in the OMA DRM system through a case study of MelOn (a well-known music distribution service in South Korea) by reverse engineering its media player equipped with a DRM agent.\",\n \"Title: Threat Assessment in the Cloud Environment: A Quantitative Approach for Security Pattern Selection\\nYear: 2016\\n\\nAbstract: Cloud computing has emerged as a fast-growing technology in the past few years. It provides a great flexibility for storing, sharing and delivering data over the Internet without investing on new technology or resources. In spite of the development and wide array of cloud usage, security perspective of cloud computing still remains its infancy. Security challenges faced by cloud environment becomes more complicated when we include various stakeholders' perspectives. In a cloud environment, security perspectives and requirements are usually designed by software engineers or security experts. Sometimes clients' requirements are either ignored or given a very high importance. In order to implement cloud security by providing equal importance to client organizations, software engineers and security experts, we propose a new methodology in this paper. We use Microsoft's STRIDE-DREAD model to assess threats existing in the cloud environment and also to measure its consequences. Our aim is to rank the threats based on the nature of its severity, and also giving a significant importance for clients' requirements on security perspective. Our methodology would act as a guiding tool for security experts and software engineers to proceed with securing process especially for a private or a hybrid cloud. Once threats are ranked, we provide a link to a well-known security pattern classification. Although we have some security pattern classification schemes in the literature, we need a methodology to select a particular category of patterns. In this paper, we provide a novel methodology to select a set of security patterns for securing a cloud software. This methodology could aid a security expert or a software professional to assess the current vulnerability condition and prioritize by also including client's security requirements in a cloud environment.\",\n \"Title: Encryption is Not Enough: Inferring User Activities on KakaoTalk with Traffic Analysis.\\nYear: 2015\\n\\nAbstract: Many people started being concerned about their privacy in delivering private chats, photographs, contacts and other personal information through mobile instant messaging services. Fortunately, in the majority of mobile instant messaging services, encrypted communication channels e.g., using the SSL/TLS protocols are used by default to protect delivered messages against eavesdropping attacks. In this paper, however, we show that encryption is not enough. For example, in a real world service named KakaoTalk, many usersu0027 online activities can effectively be identified with 99.7i¾?% accuracy even though traffic is encrypted. We present a practical traffic analysis attack using a supervised machine learning technique.\",\n \"Title: PassBYOP: Bring Your Own Picture for Securing Graphical Passwords.\\nYear: 2016\\n\\nAbstract: PassBYOP is a new graphical password scheme for public terminals that replaces the static digital images typically used in graphical password systems with personalized physical tokens, herein in the form of digital pictures displayed on a physical user-owned device such as a mobile phone. Users present these images to a system camera and then enter their password as a sequence of selections on liv...\",\n \"Title: SAN: Self-Adaptive Navigation for Drone Battery Charging in Wireless Drone Networks.\\nYear: 2016\\n\\nAbstract: This paper introduces an optimal path finding problem for drone battery charging where their batteries should be charged for the travel from a source to a destination as needed. We present a practically reasonable heuristic to solve the problem by monitoring drones' battery status and traffic conditions in real time through a cloud-based service called traffic control center. This study will be the cornerstone of path finding problems for drone battery charging in drone networks.\",\n \"Title: Detecting False Emergency Requests Using Callers' Reporting Behaviors and Locations\\nYear: 2016\\n\\nAbstract: This paper introduces a security framework to detect false emergency requests, which might significantly disturb actual rescue operations for emergency services. We design a threshold-based false request detection algorithm named FRDA to effectively filter out false requests, which is based on a reasonable scoring formula to automatically evaluate the trustworthiness of emergency requests with the caller's reporting behavior and location. This study will be a basis for developing mitigation techniques to deal with false emergency requests.\",\n \"Title: On the Guessability of Resident Registration Numbers in South Korea.\\nYear: 2016\\n\\nAbstract: This paper studies a potential risk of using real name verification systems that are prevalently used in Korean websites. Upon joining a website, users are required to enter their Resident Registration Number RRN to identify themselves. We adapt guessing theory techniques to measure RRN security against a trawling attacker attempting to guess victim's RRN using some personal information such as name, sex, and location that are publicly available e.g., on Facebook. We evaluate the feasibility of performing statistical-guessing attacks using a real-world dataset consisting of 2,326 valid name and RRN pairs collected from several Chinese websites such as Baidu. Our results show that about 4,892.5 trials are needed on average to correctly guess a RRN. Compared to the brute-force attack, our statistical-guessing attack, on average, runs about 6.74 times faster.\",\n \"Title: POSTER: WiPING: Wi-Fi signal-based PIN Guessing attack.\\nYear: 2016\\n\\nAbstract: This paper presents a new type of online password guessing attack called \\\\\\\"WiPING\\\\\\\" (Wi-Fi signal-based PIN Guessing attack) to guess a victim's PIN (Personal Identification Number) within a small number of unlock attempts. WiPING uses wireless signal patterns identified from observing sequential finger movements involved in typing a PIN to unlock a mobile device. A list of possible PIN candidates is generated from the wireless signal patterns, and is used to improve performance of PIN guessing attacks. We implemented a proof-of-concept attack to demonstrate the feasibility of WiPING. Our results showed that WiPING could be practically effective: while pure guessing attacks failed to guess all 20 PINs, WiPING successfully guessed two PINs.\",\n \"Title: Privacy-preserving nearest neighbor queries using geographical features of cellular networks.\\nYear: 2017\\n\\nAbstract: Although location-based services (LBSes), such as nearest neighbor query, have become popular, privacy remains a challenging issue for users. Many privacy preserving techniques have been proposed, but their complexity, insufficiency, and time consumption make them unattractive to users, who prefer accuracy and quickness. To address this limitation, we introduce a framework to protect user privacy for nearest neighbor queries by utilizing the basic geographical features of cellular networks. In the proposed framework, we provide two layers of spatial anonymity such that the user’s location is not directly provided to a location service provider. Based on the features of the cellular network (e.g., LTE) at the first layer, the user’s location is kept hidden under the cloaking of the base station (eNB) that provides a network connectivity to serve the user (SeNB). At the second layer, we anonymize SeNB in a group of dummy locations neighboring a central eNB (CeNB), all of which have the same query probability. Unlike most existing approaches with faked dummy locations, the proposed framework depends on real locations of eNBs to minimize the likelihood that side information might be exposed to an adversary. Moreover, our model is motivated by the practicality of employing the ubiquity of cellular networks and their geographical features. The simulation results show that the proposed scheme can achieve a decent degree of accuracy (> 98%) while providing strong privacy guarantees.\",\n \"Title: Security challenges with network functions virtualization.\\nYear: 2017\\n\\nAbstract: The advent of network functions virtualization (NFV) has revolutionized numerous network-based applications due to its several benefits such as flexibility, manageability, scalability, and security. By the software-based virtualization of network functions on a single infrastructure, NFV provides users with a framework that dynamically provisions various network services in a flexible manner. However, NFV faces several security challenges (e.g., multi-tenancy and live migration) which make it vulnerable to some cybersecurity attacks (e.g., side-channel attacks and shared resource misuse attacks). In this paper, we provide an overview of NFV, discuss potentially serious security threats on NFV and introduce effective countermeasures to mitigate those threats. Finally, we suggest some practical solutions to provide a trustworthy platform for NFV.\",\n \"Title: Analysis and comparison of fax spam detection algorithms.\\nYear: 2017\\n\\nAbstract: Spam detection is one of the important problems in these days. Many spam detection methods were proposed, but fax spam detection is not popular. It not easy to directly use existing content-based spam detection methods for fax documents because the documents are processed as image rather than text. In this paper, we propose a fax spam detection framework which is based on keyword patterns by using an Optical Character Recognition (OCR) technique. To demonstrate how effective the proposed framework is, we analyze and compare three fax spam detection algorithms (rule based method, SVM based method, and naïve Bayesian based method) with 219 normal and 212 spam documents. Our recommendation is to use naïve Bayesian based method which is capable of achieving an accuracy of 92.49%.\",\n \"Title: A flexible architecture for orchestrating network security functions to support high-level security policies.\\nYear: 2017\\n\\nAbstract: Network Functions Virtualization (NFV) has provided a new way to design and deploy network security services, but it may fail to build a practically useful ecosystem that seamlessly integrates network security services if there is no standard interface between them. We propose a generic architecture for security management service based on Network Security Functions (NSF) using NFV. The proposed architecture allows users to define their security requirements in a user-friendly manner by providing the users with high-level security interfaces that do not require specific information about network resources and protocols. We design basic components (e.g., Security policy manager, NSF capability manager, Application logic, Policy updater and Event collector) and interfaces for the proposed architecture. We introduce three use cases: (1) blacklists of dangerous domains, (2) time-dependent access control policies and (3) detection of suspicious calls for VoIP-VoLTE services. We also explain how to implement our proposed architecture with an illustrative example. Furthermore, we discuss several technical challenges to deploy the proposed architecture in a real network environment.\",\n \"Title: Wrong Siren! A Location Spoofing Attack on Indoor Positioning Systems: The Starbucks Case Study.\\nYear: 2017\\n\\nAbstract: The Internet of Things interconnects a mass of billions devices, from smartphones to cars, to provide convenient services to people. This gives immediate access to various data about the objects and the environmental context -- leading to smart services and increased efficiency. A number of retail stores have started to adopt IoT enabled services to attract customers. In particular, thanks to indoor proximity technologies, it is possible to introduce location-based smart services to customers, for example, transmitting identifiable signals that represent the locations of stores. In this article, we investigate a potential security risk involved in such technologies: physical signals used as identifiers can be captured and forged easily with today's widely available IoT software for implementing location spoofing attacks. We highlight this security risk by providing a case study: an in-depth security analysis of the recently launched Starbucks service called Siren Order.\",\n \"Title: Security and Privacy Challenges in the Internet of Things [Security and Privacy Matters].\\nYear: 2017\\n\\nAbstract: This is the first installment of the new \\\"Security and Privacy Matters\\\" column in IEEE Consumer Electronics Magazine. Security and privacy are always at the heart of everything that happens in the Consumer Electronics (CE) industry. This column aims to provide insight on various aspects of security and privacy in the CE industry.\",\n \"Title: TARD: Temporary Access Rights Delegation for guest network devices.\\nYear: 2017\\n\\nAbstract: Abstract Many cryptographic protocols were developed to support efficient group membership operations. Although those schemes can be extensively used for controlling temporary access with guest devices which do occur in many real world situations, those schemes incur a significant management overhead. For guest devices, we propose a scheme without heavy key management overheads— T emporary A ccess R ights D elegation (TARD). The proposed scheme uses a cryptographic token that can be securely constructed by a one-way function chain, used for granting a temporary membership to a guest device. Our analysis shows that the proposed scheme is theoretically secure and outperforms the certificate-based authentication schemes.\",\n \"Title: Forensic analysis of the backup database file in KakaoTalk messenger\\nYear: 2017\\n\\nAbstract: Instant messaging services should be designed to securely protect their users' personal contents such as chat messages, photos and video clips against a wide range of attacks. In general, such contents are securely encrypted in storage. In this paper, however, we demonstrated that the backup database file for chat messages in KakaoTalk (the most popularly used instant messaging service in Republic of Korea, http://www.kakao.com/talk/en) can be leaked to unauthorized users. We carefully examined the backup procedure in KakaoTalk through reverse engineering the KakaoTalk application to analyze how the backup database file was encrypted and the encryption key can be generated. Our analysis showed that the encrypted database is susceptible to off-line password guessing attacks. Based on this finding, we recommend that a secure key generation technique should be designed to improve resistance against offline password guessing attacks by using a random secret number to generate the encryption key.\",\n \"Title: I'm too Busy to Reset my LinkedIn Password: On the Effectiveness of Password Reset Emails.\\nYear: 2017\\n\\nAbstract: A common security practice used to deal with a password breach is locking user accounts and sending out an email to tell users that they need to reset their password to unlock their account. This paper evaluates the effectiveness of this security practice based on the password reset email that LinkedIn sent out around May 2016, and through an online survey conducted on 249 LinkedIn users who received that email. Our evaluation shows that only about 46% of the participants reset their passwords. The mean time taken to reset password was 26.3 days, revealing that a significant proportion of the participants reset their password a few weeks, or even months after first receiving the email. Our findings suggest that more effective persuasive measures need to be added to convince users to reset their password in a timely manner, and further reduce the risks associated with delaying password resets.\",\n \"Title: DDoS Attack Mitigation in Internet of Things Using Software Defined Networking.\\nYear: 2017\\n\\nAbstract: Securing Internet of Things (IoT) systems is a challenge because of its multiple points of vulnerability. A spate of recent hacks and security breaches has unveiled glaring vulnerabilities in the IoT. Due to the computational and memory requirement constraints associated with anomaly detection algorithms in core networks, commercial in-line (part of the direct line of communication) Anomaly Detection Systems (ADSs) rely on sampling-based anomaly detection approaches to achieve line rates and truly-inline anomaly detection accuracy in real-time. However, packet sampling is inherently a lossy process which might provide an incomplete and biased approximation of the underlying traffic patterns. Moreover, commercial routers uses proprietary software making them closed to be manipulated from the outside. As a result, detecting malicious packets on the given network path is one of the most challenging problems in the field of network security. We argue that the advent of Software Defined Networking (SDN) provides a unique opportunity to effectively detect and mitigate DDoS attacks. Unlike sampling-based approaches for anomaly detection and limitation of proprietary software at routers, we use the SDN infrastructure to relax the sampling-based ADS constraints and collect traffic flow statistics which are maintained at each SDN-enabled switch to achieve high detection accuracy. In order to implement our idea, we discuss how to mitigate DDoS attacks using the features of SDN infrastructure.\",\n \"Title: Boosting the Guessing Attack Performance on Android Lock Patterns with Smudge Attacks.\\nYear: 2017\\n\\nAbstract: Android allows 20 consecutive fail attempts on unlocking a device. This makes it difficult for pure guessing attacks to crack user patterns on a stolen device before it permanently locks itself. We investigate the effectiveness of combining Markov model-based guessing attacks with smudge attacks on unlocking Android devices within 20 attempts. Detected smudges are used to pre-compute all the possible segments and patterns, significantly reducing the pattern space that needs to be brute-forced. Our Markov-model was trained using 70% of a real-world pattern dataset that consists of 312 patterns. We recruited 12 participants to draw the remaining 30% on Samsung Galaxy S4, and used smudges they left behind to analyze the performance of the combined attack. Our results show that this combined method can significantly improve the performance of pure guessing attacks, cracking 74.17% of patterns compared to just 13.33% when the Markov model-based guessing attack was performed alone---those results were collected from a naive usage scenario where the participants were merely asked to unlock a given device. Even under a more complex scenario that asked the participants to use the Facebook app for a few minutes---obscuring smudges were added as a result---our combined attack, at 31.94%, still outperformed the pure guessing attack at 13.33%. Obscuring smudges can significantly affect the performance of smudge-based attacks. Based on this finding, we recommend that a mitigation technique should be designed to help users add obscurity, e.g., by asking users to draw a second random pattern upon unlocking a device.\",\n \"Title: SysPal: System-Guided Pattern Locks for Android\\nYear: 2017\\n\\nAbstract: To improve the security of user-chosen Android screen lock patterns, we propose a novel system-guided pattern lock scheme called \\\"SysPal\\\" that mandates the use of a small number of randomly selected points while selecting a pattern. Users are given the freedom to use those mandated points at any position. We conducted a large-scale online study with 1,717 participants to evaluate the security and usability of three SysPal policies, varying the number of mandatory points that must be used (upon selecting a pattern) from one to three. Our results suggest that the two SysPal policies that mandate the use of one and two points can help users select significantly more secure patterns compared to the current Android policy: 22.58% and 23.19% fewer patterns were cracked. Those two SysPal policies, however, did not show any statistically significant inferiority in pattern recall success rate (the percentage of participants who correctly recalled their pattern after 24 hours). In our lab study, we asked participants to install our screen unlock application on their own Android device, and observed their real-life phone unlock behaviors for a day. Again, our lab study did not show any statistically significant difference in memorability for those two SysPal policies compared to the current Android policy.\",\n \"Title: Design Of A Secure Digital Recording Protection System With Network Connected Devices\\nYear: 2017\\n\\nAbstract: We present a new recording protection system for network connected devices that belong to a user's personal network. To avoid illegal redistribution of the recorded contents through Internet, a proper content protection technology is required. However, conventional recording protection systems all lack sharing of the recorded contents without an online connection to a remote content service. Our recording protection system is designed to avoid complicated membership controls which are generally required in the existing solutions. To show the feasibility of the proposed recording protection system, we implemented a prototype with popularly used encryption algorithms (AES and RSA-OAEP). The experimental results of our prototype demonstrate that the execution time overheads incurred by the proposed system seem acceptable enough.\",\n \"Title: Towards Automated Exploit Generation For Embedded Systems\\nYear: 2016\\n\\nAbstract: Manual vulnerability discovery and exploit development on an executable are very challenging tasks for developers. Therefore, the automation of those tasks is becoming interesting in the field of software security. In this paper, we implement an approach of automated exploit generation for firmware of embedded systems by extending an existing dynamic analysis framework called Avatar. Embedded systems occupy a significant portion of the market but lack typical security features found on general purpose computers, making them prone to critical vulnerabilities. We discuss several techniques to automatically discover vulnerabilities and generate exploits for embedded systems, and evaluate our proposed approach by generating exploits for two vulnerable firmware written for a popular ARM Cortex-M3 microcontroller.\",\n \"Title: Empirical Analysis Of Ssl/Tls Weaknesses In Real Websites: Who Cares?\\nYear: 2016\\n\\nAbstract: As SSL/TLS has become the de facto standard Internet protocol for secure communication in recent years, its security issues have also been intensively studied. Even though several tools have been introduced to help administrators know which SSL/TLS vulnerabilities exist in their network hosts, it is still unclear whether the best security practices are effectively adopted to fix those vulnerabilities in real-world applications. In this paper, we present the landscape of real websites about SSL/TLS weaknesses through an automatic analysis of the possibilities of six representative SSL/TLS attacks-Heartbleed, POODLE, CCS injection, FREAK, Logjam and DROWN-on popular websites. Surprisingly, our experiments show that 45% and 52.6% of top 500 most popular global and Korean websites are still vulnerable to at least one of those attacks, respectively. We also observed several interesting trends in how websites were vulnerable to those attacks. Our findings suggest that better tools and education programs for SSL/TLS security are needed to help administrators keep their systems up-to-date with security patches.\",\n \"Title: Preventing Dns Amplification Attacks Using The History Of Dns Queries With Sdn\\nYear: 2017\\n\\nAbstract: Domain Name System (DNS) amplification attack is a sophisticated Distributed Denial of Service (DDoS) attack by sending a huge volume of DNS name lookup requests to open DNS servers with the source address spoofed as a victim host. However, from the point of view of an individual network resource such as DNS server and switch, it is not easy to mitigate such attacks because a distributed attack could be performed with multiple DNS servers and/or switches. To overcome this limitation, we propose a novel security framework using Software-Defined Networking (SDN) to store the history of DNS queries as an evidence to distinguish normal DNS responses from attack packets. Our evaluation results demonstrate that the network traffic for DNS amplification attack can completely be blocked under various network conditions without incurring a significant communication overhead.\",\n \"Title: Poster: Adversarial Examples for Classifiers in High-Dimensional Network Data.\\nYear: 2017\\n\\nAbstract: Many machine learning methods make assumptions about the data, such as, data stationarity and data independence, for an efficient learning process that requires less data. However, these assumptions may give rise to vulnerabilities if violated by smart adversaries. In this paper, we propose a novel algorithm to craft the input samples by modifying a certain fraction of input features as small as in order to bypass the decision boundary of widely used binary classifiers using Support Vector Machine (SVM). We show that our algorithm can reliably produce adversarial samples which are misclassified with 98% success rate while modifying 22% of the input features on average. Our goal is to evaluate the robustness of classification algorithms for high demensional network data by intentionally performing evasion attacks with carefully designed adversarial examples. The proposed algorithm is evaluated using real network traffic datasets (CAIDA 2007 and CAIDA 2016).\",\n \"Title: Mitigating DNS query-based DDoS attacks with machine learning on software-defined networking.\\nYear: 2017\\n\\nAbstract: Securing Internet of Things is a challenge because of its multiple points of vulnerability. In particular, Distributed Denial of Service (DDoS) attacks on IoT devices pose a major security challenge to be addressed. In this paper, we propose a DNS query-based DDoS attack mitigation system using Software-Defined Networking (SDN) to block the network traffic for DDoS attacks. With some features provided by SDN, we can analyze traffic patterns and filter suspicious network flows out. To show the feasibility of the proposed system, we particularly implemented a prototype with Dirichlet process mixture model to distinguish benign traffic from malicious traffic and conducted experiments with the dataset collected from real network traces. We demonstrate the effectiveness of the proposed method by both simulations and experiment data obtained from the real network traffic traces.\",\n \"Title: Cryptanalysis of an authentication scheme for multi-gateway wireless sensor networks\\nYear: 2017\\n\\nAbstract: Wireless sensor network has wide potential application in many fields such as military, agricultural and healthcare. However, it also has some vulnerabilities because of its openness. For this reason, many researchers have proposed various user authentication schemes for added security of wireless sensor networks. Recently, Wu et al. proposed an authentication scheme for multi-gateway wireless sensor networks in Internet of Things deployment. Wu et al. claimed that their scheme is secure against user forgery attack and session key leakage. However, we found that the scheme is vulnerable to outsider and user impersonation attacks. In this paper, we revisit Wu et al.'s scheme and analyze its vulnerabilities.\",\n \"Title: Interface to Network Security Functions for Cloud-Based Security Services.\\nYear: 2018\\n\\nAbstract: Network functions virtualization and cloud-based security services will become increasingly common in enterprise network systems to reduce the system operation costs and take advantage of the diverse network security functions (NSFs) developed by multiple vendors. In such a network environment, standardizing the interfaces to the NSFs of different vendors is essential to simplify the management of...\",\n \"Title: No Silk Road for Online Gamers!: Using Social Network Analysis to Unveil Black Markets in Online Games.\\nYear: 2018\\n\\nAbstract: Online game involves a very large number of users who are interconnected and interact with each other via the Internet. We studied the characteristics of exchanging virtual goods with real money through the processes called \\\"real money trading (RMT)\\\". This exchange might influence online game user behaviors and cause damage to the reputation of game companies. We examined in-game transactions to reveal RMT by constructing a social graph of virtual goods exchanges in an online game and identifying network communities of users.\\n\\n We analyzed approximately 6,000,000 transactions in a popular online game and inferred RMT transactions by comparing the RMT transactions crawled from an out-game market. Our findings are summarized as follows: (1) the size of the RMT market could be approximately estimated; (2) professional RMT providers typically form a specific network structure (either star-shape or chain) in the trading network, which can be used as a clue for tracing RMT transactions; and (3) the observed RMT market has evolved over time into a monopolized market with a small number of large-sized virtual goods providers.\",\n \"Title: User Credential Cloning Attacks in Android Applications: Exploiting Automatic Login on Android Apps and Mitigating Strategies.\\nYear: 2018\\n\\nAbstract: Automatic login is a commonly used feature of smartphones, because their small keyboards make it difficult to key in user credential information. However, this feature may pose a serious risk to smartphone users? privacy. The stored data for automatic login could be stolen by an attacker, resulting in identity theft. In this article, we demonstrate an execution of this attack in a systematic manne...\",\n \"Title: A Framework for Managing User-defined Security Policies to Support Network Security Functions\\nYear: 2018\\n\\nAbstract: Network Functions Virtualization (NFV) and Software Defined Networking (SDN) make it easier for security administrators to manage security policies on a network system. However, it is still challenging to map high-level security policies defined by users into low-level security policies that can be applied to network security devices. To address this problem, we introduce a framework for effectively managing user-defined security policies for network security functions based on standard interfaces that are currently being standardized in an IETF working group. To show the feasibility of the proposed framework, we implemented a prototype based on the RESTCONF protocol and showed that the proposed framework can be applied in real-world scenarios for network separation, DDoS mitigation and ransomeware prevention.\",\n \"Title: Secure and DoS-Resilient Fragment Authentication in CCN-Based Vehicular Networks.\\nYear: 2018\\n\\nAbstract: Content-Centric Networking (CCN) is considered as a promising alternative to traditional IP-based networking for vehicle-to-everything communication environments. In general, CCN packets must be fragmented and reassembled based on the Maximum Transmission Unit (MTU) size of the content delivery path. It is thus challenging to securely protect fragmented packets against attackers who intentionally inject malicious fragments to disrupt normal services on CCN-based vehicular networks. This paper presents a new secure content fragmentation method that is resistant to Denial-of-Service (DoS) attacks in CCN-based vehicular networks. Our approach guarantees the authenticity of each fragment through the immediate fragment verification at interim nodes on the routing path. Our experiment results demonstrate that the proposed approach provides much stronger security than the existing approach named FIGOA, without imposing a significant overhead in the process. The proposed method achieves a high immediate verification probability of 98.2% on average, which is 52% higher than that of FIGOA, while requiring only 14% more fragments than FIGOA.\",\n \"Title: POSTER: I Can't Hear This Because I Am Human: A Novel Design of Audio CAPTCHA System.\\nYear: 2018\\n\\nAbstract: A CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) provides the first line of defense to protect websites against bots and automatic crawling. Recently, audio-based CAPTCHA systems are started to use for visually impaired people in many internet services. However, with the recent improvement of speech recognition and machine learning system, audio CAPTCHAs have come to struggle to distinguish machines from users, and this situation will likely continue to worsen. Unlike conventional CAPTCHA systems, we propose a new conceptual audio CAPTCHA system, combining certain sound, which is only understandable by a machine. Our experiment results demonstrate that the tested speech recognition systems always provide correct responses for our CAPTCHA samples while humans cannot possibly understand them. Based on this computational gap between the human and machine, we can detect bots with their correct responses, rather than their incorrect ones.\",\n \"Title: POSTER: Can We Use Biometric Authentication on Cloud?: Fingerprint Authentication Using Homomorphic Encryption.\\nYear: 2018\\n\\nAbstract: Even though biometric authentication such as fingerprint authentication is popularly used, there are few network services supporting biometric authentication because many users have serious privacy concerns about leakage of the biometric data on a server. For example, in fingerprint authentication, a user's raw fingerprint is typically stored in plaintext form. Unlike conventional text passwords, we cannot use a cryptographic hash function such as SHA-256 because it is very hard to obtain the same fingerprint features even when the exactly same finger is scanned multiple times. In this paper, we present a fingerprint authentication mechanism using the Fastest Homomorphic Encryption in the West (FHEW) library for Learning With Errors (LWE) scheme. Our implementation allows us to securely store fingerprint data on a network server using homomorphic encryption to calculate the distance between two encrypted fingerprint data without decrypting them. To show the efficiency of our implementation, we used \\\"NIST special database 9'' containing 4,000 fingerprint samples. Our results show that two fingerprints can be efficiently compared with about 209 seconds on average even when they are securely stored in encrypted form.\",\n \"Title: POSTER: DeepCRACk: Using Deep Learning to Automatically CRack Audio CAPTCHAs.\\nYear: 2018\\n\\nAbstract: A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a defensive mechanism designed to differentiate humans and computers to prevent unauthorized use of online services by automated attacks. They often consist of a visual or audio test that humans can perform easily but that bots cannot solve. However, with current machine learning techniques and open-source neural network architectures, it is now possible to create a self-contained system that is able to solve specific CAPTCHA types and outperform some human users. In this paper, we present a neural network that leverages Mozilla's open source implementation of Baidu's Deep Speech architecture; our model is currently able to solve the audio version of an open-source CATPCHA system (named SimpleCaptcha) with 98.8% accuracy. Our network was trained on 100,000 audio samples generated from SimpleCaptcha and can solve new SimpleCaptcha audio tests in 1.25 seconds on average (with a standard deviation of 0.065 seconds). Our implementation seems additionally promising because it does not require a powerful server to function and is robust to adversarial examples that target Deep Speech's pre-trained models.\",\n \"Title: The Personal Identification Chord: A Four ButtonAuthentication System for Smartwatches.\\nYear: 2018\\n\\nAbstract: Smartwatches support access to a wide range of private information but little is known about the security and usability of existing smartwatch screen lock mechanisms. Prior studies suggest that smartwatch authentication via standard techniques such as 4-digit PINs is challenging and error-prone. We conducted interviews to shed light on current practices, revealing that smartwatch users consider the ten-key keypad required for PIN entry to be hard to use due to its small button sizes. To address this issue, we propose the Personal Identification Chord (PIC), an authentication system based on a four-button chorded keypad that enables users to enter ten different inputs via taps to one or two larger buttons. Two studies assessing usability and security of our technique indicate PICs lead to increases in setup and (modestly) recall time, but can be entered accurately while maintaining high recall rates and may improve guessing entropy compared to PINs.\",\n \"Title: CyTIME: Cyber Threat Intelligence ManagEment framework for automatically generating security rules.\\nYear: 2018\\n\\nAbstract: It is becoming increasingly necessary for organizations to build a Cyber Threat Intelligence (CTI) platform to fight against sophisticated attacks. To reduce the risk of cyber attacks, security administrators and/or analysts can use a CTI platform to aggregate relevant threat information about adversaries, targets and vulnerabilities, analyze it and share key observations from the analysis with collaborators. In this paper, we introduce CyTIME (Cyber Threat Intelligence ManagEment framework) which is a framework for managing CTI data. CyTIME can periodically collect CTI data from external CTI data repositories via standard interfaces such as Trusted Automated Exchange of Indicator Information (TAXII). In addition, CyTIME is designed to automatically generate security rules without human intervention to mitigate discovered new cybersecurity threats in real time. To show the feasibility of CyTIME, we performed experiments to measure the time to complete the task of generating the security rule corresponding to a given CTI data. We used 1,000 different CTI files related to network attacks. Our experiment results demonstrate that CyTIME automatically generates security rules and store them into the internal database within 12.941 seconds on average (max = 13.952, standard deviation = 0.580).\",\n \"Title: Efficient and Secure Biometric-Based User Authenticated Key Agreement Scheme with Anonymity.\\nYear: 2018\\n\\nAbstract: At present, a number of users employ an authentication protocol so as to enjoy protected electronic transactions in wireless networks. In order to establish an efficient and robust the transaction system, numerous researches have been conducted relating to authentication protocols. Recently, Kaul and Awasthi presented an user authentication and key agreement scheme, arguing that their scheme is able to resist various types of attacks and preserve diverse security properties. However, this scheme possesses critical vulnerabilities. First, the scheme cannot prevent two kinds of attacks, including off-line password guessing attacks and user impersonation attacks. Second, user anonymity rule cannot be upheld. Third, session key can be compromised by an attacker. Fourth, there is high possibility that the time synchronization trouble occurs. Therefore, we suggest an upgraded version of the user authenticated key agreement method that provides enhanced security. Our security and performance analysis shows that compared, to other associated protocols, our method not only improves the security level but also ensures efficiency.\",\n \"Title: Two-Thumbs-Up: Physical protection for PIN entry secure against recording attacks.\\nYear: 2018\\n\\nAbstract: We present a new Personal Identification Number (PIN) entry method for smartphones that can be used in security-critical applications, such as smartphone banking. The proposed “Two-Thumbs-Up” (TTU) scheme is resilient against observation attacks such as shoulder-surfing and camera recording, and guides users to protect their PIN information from eavesdropping by shielding the challenge area on the touch screen. To demonstrate the feasibility of TTU, we conducted a user study for TTU, and compared it with existing authentication methods (Normal PIN, Black and White PIN, and ColorPIN) in terms of usability and security. The study results demonstrate that TTU is more secure than other PIN entry methods in the presence of an observer recording multiple authentication sessions.\",\n \"Title: When Harry Met Tinder: Security Analysis of Dating Apps on Android.\\nYear: 2018\\n\\nAbstract: As the number of smartphone users has increased, so has the popularity of dating apps such as Tinder, Hinge, Grindr and Bumbler. At the same time, however, many users have growing privacy concerns about these applications disclosing their sensitive and private information to other service providers and/or strangers. This is particularly exacerbated due to the nature of dating apps requiring access to users' personal contents such as chat messages, photos, video clips and locations. In this paper, we present an analysis of security and privacy issues in popular dating apps on Android. We carefully analyze the possibility of software vulnerabilities on the five most popular dating apps on Android through network traffic analyses and reverse engineering techniques for each dating app. Our experiment results demonstrate that user credential data can be stolen from all five applications; three apps may lead to the disclosure of user profiles, and one app may lead to the disclosure of chat messages.\",\n \"Title: An Implementation and Evaluation of Progressive Authentication Using Multiple Level Pattern Locks.\\nYear: 2018\\n\\nAbstract: This paper presents a possible implementation of progressive authentication using the Android pattern lock. Our key idea is to use one pattern for two access levels to the device; an abridged pattern is used to access generic applications and a second, extended and higher-complexity pattern is used less frequently to access more sensitive applications. We conducted a user study of 89 participants and a consecutive user survey on those participants to investigate the usability of such a pattern scheme. Data from our prototype showed that for unlocking low-security applications the median unlock times for users of the multiple pattern scheme and conventional pattern scheme were 2824 ms and 5589 ms respectively, and the distributions in the two groups differed significantly (Mann-Whitney U test, p-value less than 0.05, two-tailed). From our user survey, we did not find statistically significant differences between the two groups for their qualitative responses regarding usability and security (t-test, p-value greater than 0.05, two-tailed), but the groups did not differ by more than one satisfaction rating at 90% confidence.\",\n \"Title: MEDUSA: Malware Detection Using Statistical Analysis of System's Behavior\\nYear: 2018\\n\\nAbstract: Traditional malware detection techniques have focused on analyzing known malware samples' codes and behaviors to construct an effective database of malware signatures. In recent times, however, such techniques have inherently exposed limitations in detecting unknown malware samples and maintaining the database up-to-date, as many polymorphic and metamorphic malware samples are newly created and spread very quickly throughout the Internet. To address the limitations of existing signature-based malware scanners, we take a different view and focus on designing a novel malware detection framework, called MEDUSA (MalwarE Detection Using Statistical Analysis of system's behavior), for building a model for a system's behaviors with normal processes. Unlike traditional approaches for malware detection, MEDUSA has the potential to effectively detect unknown malware samples because it is designed to monitor a system's behavior and detect significant changes from the system's normal status. In this paper, we specifically discuss several important considerations that must be taken into account to successfully develop MEDUSA in practice.\",\n \"Title: A framework for DNS naming services for Internet-of-Things devices.\\nYear: 2019\\n\\nAbstract: This paper proposes a new naming framework for Domain Name System (DNS) Name Autoconfiguration (called DNSNA) for Internet of Things (IoT) devices in Internet Protocol (IP) version 6 (IPv6) and IP version 4 (IPv4) networks. As the number of IoT devices increases, it can be a burden for users to manually configure the DNS names of the IoT devices. We propose DNSNA to provide an efficient DNS name management for IoT devices, supporting an IoT device’s DNS name auto-generation, its DNS name auto-registration, device discovery, and service discovery. A user can easily use the registered DNS information of the IoT devices for both device discovery and service discovery through DNSNA. DNSNA uses IPv6 Neighbor Discovery (ND) protocol for IPv6 IoT devices and Dynamic Host Configuration Protocol (DHCP) for IPv4 IoT devices, respectively, in the IoT DNS name autoconfiguration. With either ND or DHCP, the IoT devices can obtain a DNS suffix and construct their DNS name. Also, through a physical-contact-based authentication of a user’s smartphone with an IoT device over Near Field Communication (NFC), an authenticated IoT device can automatically register its DNS name and the corresponding IP address into a local authoritative DNS server in a secure way. Through real experiments and analysis, it is shown that DNSNA can reduce the average number of packets by 60.8% and the accumulated packet volume by 97% in comparison with the existing DNS naming service (i.e., mDNS) for IoT devices in an IPv6 network.\",\n \"Title: Statistical Application Fingerprinting for DDoS Attack Mitigation\\nYear: 2019\\n\\nAbstract: Because of the dynamic nature of network traffic patterns, such as new traffic application arrivals or flash events, it is becoming increasingly difficult for conventional anomaly detection systems to separate various applications based on their traffic patterns. In this paper, by leveraging transport layer packet-level and flow-level features, new structures called \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">application fingerprints</italic>\\n are generated, which express such features in a compact and efficient manner. Based on the generated fingerprints, we propose a novel traffic classification framework. The proposed system generates profiles of normal applications using a multi-modal probability distribution. The proposed classification framework is then extended to detect distributed denial of service attacks from the collected statistical information at flow level. To demonstrate the feasibility of the proposed system, we evaluate its performance using five real-world traffic datasets. The experiment results show that the proposed method is capable of achieving an accuracy of over 97%, whereas the misclassification rate is only 2.5%.\",\n \"Title: OTR: Offline OTR messaging system under network disruption.\\nYear: 2019\\n\\nAbstract: Providing a secure and efficient communication system under network disruption without a trusted third party remains a challenging issue. To develop a secure and efficient system in such situations, we extend the conventional Off-The-Record (OTR) protocol into a new protocol named offline OTR (O2TR). O2TR provides end-to-end security between users without requiring the assumption that they are persistently connected to each other. To show the feasibility of the proposed protocol, we implemented a prototype to support O2TR based on the Gajim XMMP instant messaging platform. Our experiments showed that O2TR can be used reliably even when the corresponding network party is temporarily broken down. Moreover, O2TR provides an efficient way to resume private sessions which is about 34% faster than the original OTR. We also proved the secrecy of O2TR using an automated verification tool called AVISPA.\",\n \"Title: k -Depth Mimicry Attack to Secretly Embed Shellcode into PDF Files\\nYear: 2017\\n\\nAbstract: This paper revisits the shellcode embedding problem for PDF files. We found that a popularly used shellcode embedding technique called reverse mimicry attack has not been shown to be effective against well-trained state-of-the-art detectors. To overcome the limitation of the reverse mimicry method against existing shellcode detectors, we extend the idea of reverse mimicry attack to a more generalized one by applying the k-depth mimicry method to PDF files. We implement a proof-of-concept tool for the k-depth mimicry attack and show its feasibility by generating shellcode-embedded PDF files to evade the best known shellcode detector (PDFrate) with three classifiers. The experimental results show that all tested classifiers failed to effectively detect the shellcode embedded by the k-depth mimicry method when k >= 20.\",\n \"Title: Detecting Encrypted Traffic: A Machine Learning Approach\\nYear: 2016\\n\\nAbstract: Detecting encrypted traffic is increasingly important for deep packet inspection (DPI) to improve the performance of intrusion detection systems. We propose a machine learning approach with several randomness tests to achieve high accuracy detection of encrypted traffic while requiring low overhead incurred by the detection procedure. To demonstrate how effective the proposed approach is, the performance of four classification methods (Naive Bayesian, Support Vector Machine, CART and AdaBoost) are explored. Our recommendation is to use CART which is not only capable of achieving an accuracy of 99.9% but also up to about 2.9 times more efficient than the second best candidate (Naive Bayesian).\",\n \"Title: Design and Analysis of Push Notification-Based Malware on Android.\\nYear: 2018\\n\\nAbstract: Establishing secret command and control (C&C) channels from attackers is important in malware design. This paper presents design and analysis of malware architecture exploiting push notification services as C&C channels. The key feature of the push notification-based malware design is remote triggering, which allows attackers to trigger and execute their malware by push notifications. The use of push notification services as covert channels makes it difficult to distinguish this type of malware from other normal applications also using the same services. We implemented a backdoor prototype on Android devices as a proof-of-concept of the push notification-based malware and evaluated its stealthiness and feasibility. Our malware implementation effectively evaded the existing malware analysis tools such as 55 antimalware scanners from VirusTotal and SandDroid. In addition, our backdoor implementation successfully cracked about 98% of all the tested unlock secrets (either PINs or unlock patterns) in 5 seconds with only a fraction (less than 0.01%) of the total power consumption of the device. Finally, we proposed several defense strategies to mitigate push notification-based malware by carefully analyzing its attack process. Our defense strategies include filtering subscription requests for push notifications from suspicious applications, providing centralized management and access control of registration tokens of applications, detecting malicious push messages by analyzing message contents and characteristic patterns demonstrated by malicious push messages, and detecting malware by analyzing the behaviors of applications after receiving push messages.\",\n \"Title: Data-Driven Selection Of Security Application Frameworks During Architectural Design\\nYear: 2019\\n\\nAbstract: The selection of application frameworks is an important aspect of architectural design. Selection often requires satisficing, that is, searching a potentially large space of design alternatives until an acceptable solution is found. There is, however, little help for architects in selecting software frameworks. In this paper we investigate the criteria used by practicing software architects in selecting security frameworks. We also propose how information associated with some of the criteria that are important to architects can be obtained manually or in an automated way from online sources such as GitHub. Our ultimate goal is to identify measures associated with these criteria that can be helpful in providing support for architects to select software frameworks.\",\n \"Title: Threat Modeling and Analysis of Voice Assistant Applications.\\nYear: 2018\\n\\nAbstract: Voice assistant is an application that helps users to interact with their devices using voice commands in a more intuitive and natural manner. Recently, many voice assistant applications have been popularly deployed on smartphones and voice-controlled smart speakers. However, the threat and security of those applications have been examined only in very few studies. In this paper, we identify potential threats to voice assistant applications and assess the risk of those threats using the STRIDE and DREAD models. Our threat modeling demonstrates that generic voice assistants can potentially have 16 security threats. To mitigate the identified threats, we also discuss several defense strategies.\",\n \"Title: Digital forensic analysis of encrypted database files in instant messaging applications on Windows operating systems: Case study with KakaoTalk, NateOn and QQ messenger.\\nYear: 2019\\n\\nAbstract: Instant messaging applications store users' personal data (e.g., user profile, chat messages, photos and video clips). Because those data typically include privacy sensitive information, most instant messaging applications are trying to protect the stored data in an encrypted form so that the authorized messaging application itself can only access the data. In this paper, we analyzed the locations and file formats of personal data files in three instant messaging applications (KakaoTalk, NateOn, and QQ) which are the most popularly used in China and South Korea. We particularly examined the encryption and decryption procedures for internal databases in those messaging applications through reverse-engineering. Our analysis results demonstrate how the database files of those instant messaging applications are stored and encrypted. Moreover, in the cases of KakaoTalk and NateOn applications, we found that their encrypted database files can successfully be recovered without requiring user password. We also found that QQ messenger stores the encryption key for the database files into an external server. This implementation may raise another privacy concern because users’ personal data can be freely accessed by the service provider without user consent.\",\n \"Title: Bitcoin vs. Bitcoin Cash: Coexistence or Downfall of Bitcoin Cash?\\nYear: 2019\\n\\nAbstract: Bitcoin has become the most popular cryptocurrency based on a peer-to-peer network. In Aug. 2017, Bitcoin was split into the original Bitcoin (BTC) and Bitcoin Cash (BCH). Since then, miners have had a choice between BTC and BCH mining because they have compatible proof-of-work algorithms. Therefore, they can freely choose which coin to mine for higher profit, where the profitability depends on both the coin price and mining difficulty. Some miners can immediately switch the coin to mine only when mining difficulty changes because the difficulty changes are more predictable than that for the coin price, and we call this behavior fickle mining. In this paper, we study the effects of fickle mining by modeling a game between two coins. To do this, we consider both fickle miners and some factions (e.g., BITMAIN for BCH mining) that stick to mining one coin to maintain that chain. In this model, we show that fickle mining leads to a Nash equilibrium in which only a faction sticking to its coin mining remains as a loyal miner to the less valued coin (e.g., BCH), where loyal miners refer to those who conduct mining even after coin mining difficulty increases. This situation would cause severe centralization, weakening the security of the coin system. To determine which equilibrium the competing coin systems (e.g., BTC vs. BCH) are moving toward, we traced the historical changes of mining power for BTC and BCH and found that BCH often lacked loyal miners until Nov. 13, 2017, when the difficulty adjustment algorithm of BCH mining was changed. However, the change in difficulty adjustment algorithm of BCH mining led to a state close to the stable coexistence of BTC and BCH. We also demonstrate that the lack of BCH loyal miners may still be reached when a fraction of miners automatically and repeatedly switches to the most profitable coin to mine (i.e., automatic mining). According to our analysis, as of Dec. 2018, loyal miners to BCH would leave if more than about 5% of the total mining capacity for BTC and BCH has engaged in the automatic mining. In addition, we analyze the recent “hash war” between Bitcoin ABC and SV, which confirms our theoretical analysis. Finally, we note that our results can be applied to any competing cryptocurrency systems in which the same hardware (e.g., ASICs or GPUs) can be used for mining. Therefore, our study brings new and important angles in competitive coin markets: a coin can intentionally weaken the security and decentralization level of the other rival coin when mining hardware is shared between them, allowing for automatic mining.\",\n \"Title: CBDN: Cloud-Based Drone Navigation for Efficient Battery Charging in Drone Networks\\nYear: 2019\\n\\nAbstract: For long-distance flying, drones often need to charge their battery at quick battery-charging machines (QCMs) because of their limited battery capacity. If a drone individually chooses a QCM without any coordination, a drone network may experience QCM congestion when multiple drones select the same QCM. This QCM congestion may lead to an increasing drone traffic delay. In order to solve this problem, we propose a cloud-based drone navigation (CBDN) system for efficient drone battery charging in drone networks. In order to achieve this goal, the CBDN gathers drone traffic information and determines efficient drone routes so as to minimize the overall QCM congestion level for drone battery charging using cloud-based management. Our key idea is to find globally coordinated drone routes so as to minimize the total traffic delay in a drone network by reducing the overall QCM congestion level. In order to demonstrate the effectiveness of the proposed system, we evaluated the performance of CBDN by simulating a drone network under various network conditions. The simulation results show that CBDN is more efficient than the existing shortest-path-based drone route planning algorithms in terms of end-to-end traffic delay and QCM average utilization.\",\n \"Title: The Light Will Be with You. Always -- A Novel Continuous Mobile Authentication with the Light Sensor\\nYear: 2019\\n\\nAbstract: Existing continuous authentication proposals tend to have two major drawbacks. First, touch-based smartphone authentication approaches typically require explicit user interactions with the smartphone to collect sufficient touch data. These approaches may provide an attacker the opportunity to steal a victim's sensitive data before the system detects the attacker's intrusion. Likewise, an attacker may disable the continuous authentication scheme itself before detection. Second, sensor-based continuous authentication approaches inherently suffer from high energy consumption due to the constant usage of multiple sensors. In this paper, we present a novel continuous authentication system that collects light sensor data from a user's smartphone and analyzes them to authenticate users using support vector machines. We focus on the possibility of collecting light sensor data from users' smartphones while they are conducting daily behaviors to develop an anomaly detection system.\",\n \"Title: 80% of Block Propagation Rate is Enough -- Towards Secure and Efficient PoW-based Blockchain Consensus\\nYear: 2019\\n\\nAbstract: Recently, Samsung released Galaxy S10 supporting the cryptowallet feature [5]. However, it is still questionable whether cryptocurrency can be popularly used for mobile payments because processing transactions in existing blockchain systems are too slow. For example, public blockchain systems such as Bitcoin [6] (7 transactions per second (TPS)) and Ethereum (15 TPS) are significantly slower than mainstream payment systems such as Visa (2,000 TPS) using a centralized database.\",\n \"Title: Automated Cash Mining Attacks On Mobile Advertising Networks\\nYear: 2019\\n\\nAbstract: Rewarded advertisements are popularly used in the mobile advertising industry. In this paper, we analyze several rewarded advertisement applications to discover security weaknesses, which allow malicious users to automatically generate in-app activities for earning cash rewards on advertisement networks; we call this attack automated cash mining. To show the risk of this attack, we implemented automated cashing attacks on four popularly used Android applications (Cash Slide, Fronto, Honey Screen and Screen Stash) with rewarded advertisements through reverse engineering and demonstrated that all the tested reward apps are vulnerable to our attack implementation.\",\n \"Title: Efficient Software Implementation of Homomorphic Encryption for Addition and Multiplication Operations.\\nYear: 2019\\n\\nAbstract: Fully homomorphic encryption enables any type of calculation on encrypted data. There are several crypto libraries that provide such fully homomorphic encryption. However, since most libraries only support single level binary circuit operations, it is required for developers to efficiently implement basic arithmetic algorithms such as addition, subtraction, multiplication, and division for their own applications. In this paper, we propose fast binary addition and multiplication algorithms to support various bit-wise operations. To show the feasibility of the proposed algorithms, we implemented the proposed algorithms for 16, 32, 48, and 64 bits integers using the TFHE library. Our experiment results demonstrate that the proposed addition operation decreases the running time by 11 to 12%, and our multiplication implementation is about 3 to 4 times faster than the non-threaded method for 16, 32, 48 and 64 bits integers.\",\n \"Title: Understanding Users' Risk Perceptions about Personal Health Records Shared on Social Networking Services.\\nYear: 2019\\n\\nAbstract: To understand users' risk perceptions about sharing their PHR on SNS, we first conducted a qualitative user study by interviewing 16 participants. Next, we conducted a large-scale online user study with 497 participants in the U.S. to validate our qualitative results from the first study. Our study results show that a majority of users do not show strong motivation of sharing PHR on SNS due to several concerns such as misuse/abuse and security issues of shared PHR. In particular, participants are highly concerned about sharing diseases and diagnostic test results than other types of PHRs (e.g., details of hospital visits and medical interviews). However, we found about 55.13% of the participants have the experiences of sharing their health-related information on SNS. Also, we learned that users' sharing behavior for disease data can be significantly influenced by the severity/type of the disease as well as preferred recipients. Based on our findings, we propose a recommendation method to automatically determine whether users' posts can be shared with everyone on SNS by analyzing the keywords frequently occurred in health-related posts. Our implementation using Random Forest achieved an F-measure of 87.4%, indicating that PHR can be restrictively shared with high accuracy, when sharing health-related posts on SNS.\",\n \"Title: Decamouflage: A Framework to Detect Image-Scaling Attacks on CNN\\nYear: 2021\\n\\nAbstract: Image-scaling is a typical operation that processes the input image before feeding it into convolutional neural network models. However, it is vulnerable to the newly revealed image-scaling attack. This work presents an image-scaling attack detection framework, Decamouflage, consisting of three independent detection methods: scaling, filtering, and steganalysis, to detect the attack through examining distinct image characteristics. Decamouflage has a pre-determined detection threshold that is generic. More precisely, as we have validated, the threshold determined from one dataset is also applicable to other different datasets. Extensive experiments show that Decamouflage achieves detection accuracy of 99.9% and 98.5% in the white-box and the black-box settings, respectively. We also measured its running time overhead on a PC with an Intel i5 CPU and 8GB RAM. The experimental results show that image-scaling attacks can be detected in milliseconds. Moreover, Decamouflage is highly robust against adaptive image-scaling attacks (e.g., attack image size variances).\",\n \"Title: Towards Usable And Secure Location-Based Smartphone Authentication\\nYear: 2021\\n\\nAbstract: The concept of using location information to unlock smartphones is widely available on Android phones. To date, however, not much research has been conducted on investigating security and usability requirements for designing such location-based authentication services. To bridge this gap, we interviewed 18 participants, studying users' perceptions and identifying key design requirements such as the need to support fine-grained indoor location registration and location (unlock coverage) size adjustment. We then conducted a field study with 29 participants and a fully-functioning application to study real-world usage behaviors. On average, the participants were able to reduce about 36% of manual unlock attempts by using our application for three weeks. 28 participants enduringly used registered locations to unlock their phones despite being able to delete them during the study and unlock manually instead. Worryingly, however, 23 participants registered at least one insecure location - defined as a location where an unwanted adversary can physically access their phones - as a trusted location mainly due to convenience or low (perceived) likelihood of phones being attacked. 52 out of 65 total registered locations were classified as insecure by the definition above. Interestingly, regardless of whether locations were considered secure or insecure, the participants preferred to select large phone unlock coverage areas.\",\n \"Title: ARGH!: Automated Rumor Generation Hub\\nYear: 2021\\n\\nAbstract: ABSTRACTIt is still challenging to effectively identify rumors due to rapid changes in people's interests and perceptions. To enhance rumor detectors, we first need to better understand which rumors are effective (in terms of bypassing detection) and their characteristics. In this paper, we introduce ARGH, a novel framework to automatically generate rumors using recent advancements in natural language processing, customized to target and generate specific topics. To show the effectiveness of ARGH, we conducted a user study with 212 participants and analyzed how well humans can detect the rumors generated by ARGH, and we also tested its performance against the state-of-the-art rumor detection model PLAN [17]. Surprisingly, the experimental results demonstrate that the generated rumors are significantly harder to identify as rumors than hand-written rumors, degrading the detection accuracy by both humans and machines by 18.87% and 17.62%, respectively. We believe that ARGH will be a useful tool to obtain high quality and evasive rumor datasets quickly, which is often a tedious and time consuming task. Further, our analysis results provide valuable insight into how to characterize evasive rumors and how they can be generated, which will help to enhance the existing rumor detection techniques.\",\n \"Title: On the Robustness of Intrusion Detection Systems for Vehicles Against Adversarial Attacks\\nYear: 2021\\n\\nAbstract: Because connected cars typically have several communication capabilities (through 5G, WiFi, and Bluetooth), and third-party applications can be installed on the cars, it would be essential to deploy intrusion detection systems (IDS) to prevent attacks from external attackers or malicious applications. Therefore, many IDS proposals have been presented to protect the controller area network (CAN) in a vehicle. Some studies showed that deep neural network models could be effectively used to detect various attacks on the CAN bus. However, it is still questionable whether such an IDS is sufficiently robust against adversarial attacks that are crafted aiming to target the IDS. In this paper, we present a genetic algorithm to generate adversarial CAN attack messages for Denial-of-Service (DoS), fuzzy, and spoofing attacks to target the state-of-the-art deep learning-based IDS for CAN. The experimental results demonstrate that the state-of-the-art IDS is not effective in detecting the generated adversarial CAN attack messages. The detection rates of the IDS were significantly decreased from 99.27%, 96.40%, and 99.63% to 2.24%, 11.59%, and 0.01% for DoS, fuzzy, and spoofing attacks, respectively.\",\n \"Title: Security Evaluation of n-Choose-k-Sum PUFs Against Modeling Attacks\\nYear: 2021\\n\\nAbstract: A physical unclonable function (PUF) generates hardware intrinsic volatile secrets by exploiting uncontrollable manufacturing randomness. Several PUF candidates use challenge-response pairs (CRPs) to enhance their security. A practically plausible idea for PUF is to use the technique called n-Choose-k-Sum (nCk) structure/topology, exemplified by the memristive device based on strong PUF (mrSPUF). The previous analysis claimed that nCk-PUF is resilient to modeling attacks. This paper provides numerical security evaluations on simulated CRPs - we first construct a mathematical model of nCk-PUF, and then analyze the possibility of modeling attacks using machine learning (ML). Our analysis demonstrates that our modeling attacks could break the unpredictability of nCk-PUF even though the non-linearity of nCk-PUF could be increased due to XOR-operations on its circuit. Our analysis demonstrates that our modeling attacks could break the unpredictability of nCk-PUF even though the non-linearity of nCk-PUF could be increased due to XOR-operations on its circuit. Consequently, our analysis suggest that n-Choose-k-Sum PUFs (including mrSPUF) sharing similar topology could be insecure. It should be careful when utilizing nCk-PUF for strong PUF applications, and it is suggested to add some security blocks to protect the challenge-response interface, such as the Lockdown-PUF with additional random number generator (RNG), TREVERSE with additional Hash.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":101,"string":"101"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":284,"string":"284"}}},{"rowIdx":285,"cells":{"question_id":{"kind":"string","value":"Miguel Correia"},"question":{"kind":"string","value":"Generate an abstract for the title \"Anomaly-based intrusion detection in software as a service\" using the following items: Anomaly-based IDS, Software as a service, web applications, large dimensions, accuracy."},"answer":{"kind":"string","value":"Anomaly-based intrusion detection systems (IDS) have the ability of detecting previously unknown attacks, which is important since new vulnerabilities and attacks are constantly appearing. Software as a service web applications are currently much targeted by attacks, so they are an obvious application for such IDSs. The paper presents a study of the use of anomaly-based IDSs with data from a production environment hosting a web application of large dimensions. It describes how challenges like processing a large number of requests and obtaining training data without attacks were solved. It also presents an evaluation comparing the accuracy obtained with the different types of models that were used to represent normal behavior."},"correct_answer":{"kind":"string","value":"Anomaly-based intrusion detection systems (IDS) have the ability of detecting previously unknown attacks, which is important since new vulnerabilities and attacks are constantly appearing. Software as a service web applications are currently much targeted by attacks, so they are an obvious application for such IDSs. The paper presents a study of the use of anomaly-based IDSs with data from a production environment hosting a web application of large dimensions. It describes how challenges like processing a large number of requests and obtaining training data without attacks were solved. It also presents an evaluation comparing the accuracy obtained with the different types of models that were used to represent normal behavior."},"documents":{"kind":"list like","value":["Title: Active quorum systems\nYear: 2010\n\nAbstract: This paper outlines a flexible suite of object replication protocols that brings together Byzantine quorum systems registers and state machine replication. These protocols enable the implementation of Byzantine fault-tolerant applications that make minimal assumptions about the environment and that run in at most two more communication steps in almost all cases of non-favorable executions (in comparison with favorable executions).","Title: RITAS: Services for Randomized Intrusion Tolerance\nYear: 2011\n\nAbstract: Randomized agreement protocols have been around for more than two decades. Often assumed to be inefficient due to their high expected communication and computation complexities, they have remained overlooked by the community-at-large as a valid solution for the deployment of fault-tolerant distributed systems. This paper aims to demonstrate that randomization can be a very competitive approach even in hostile environments where arbitrary faults can occur. A stack of randomized intrusion-tolerant protocols is described and its performance evaluated under several settings in both local-area-network (LAN) and wide-area-network environments. The stack provides a set of relevant services ranging from basic communication primitives up to atomic broadcast.The experimental evaluation shows that the protocols are efficient, especially in LAN environments where no performance reduction is observed under certain Byzantine faults.","Title: On the Effects of Finite Memory on Intrusion-Tolerant Systems\nYear: 2007\n\nAbstract: Intrusion tolerance has been proposed as a new paradigm for computer systems security [2, 7]. The idea is to apply the fault tolerance paradigm in the domain of systems security, accepting that malicious faults (attacks, intrusions) can never be entirely prevented, and that highly resilient systems have to tolerate these faults.","Title: Securing energy metering software with automatic source code correction.\nYear: 2013\n\nAbstract: Industry is using power meters to monitor the consumption of energy and achieving cost savings. This monitoring often involves energy metering software with a web interface. However, web applications often have vulnerabilities that can be exploited by cyber-attacks. We present an approach and a tool to solve this problem by analyzing the application source code and automatically inserting fixes to remove the discovered vulnerabilities. We demonstrate the use of the tool with two open source energy metering applications in which it found and corrected 17 vulnerabilities. By looking in more detail into some of these vulnerabilities, we argue that they are very serious, leading to the following impacts: violation of user privacy, counter the benefits of energy metering, and serve as entering points for attacks on other user software.","Title: Evaluating Byzantine Quorum Systems\nYear: 2007\n\nAbstract: Replication is a mechanism extensively used to guaran- tee the availability and good performance of data storage services. Byzantine Quorum Systems (BQS) have been pro- posed as a solution to guarantee the consistency of that kind of services, even if some of the replicas fail arbitrar- ily. Many BQS have been proposed recently, but compar- ing their performance is not simple. In fact, it has been shown that theoretical metrics like the number of steps or communication rounds say as much about the practical per- formance of distributed algorithms as they hide. This pa- per presents a comparative evaluation of several BQS al- gorithms in the literature. The evaluation is based both on experiments and simulations. For that purpose, a framework for evaluating BQS called BQSNeko was developed. The re- sults of the evaluation allow a better understanding of the algorithms and the tradeoffs involved.","Title: Efficient Byzantine Fault-Tolerance\nYear: 2013\n\nAbstract: We present two asynchronous Byzantine fault-tolerant state machine replication (BFT) algorithms, which improve previous algorithms in terms of several metrics. First, they require only 2f+1 replicas, instead of the usual 3f+1. Second, the trusted service in which this reduction of replicas is based is quite simple, making a verified implementation straightforward (and even feasible using commercial trusted hardware). Third, in nice executions the two algorithms run in the minimum number of communication steps for nonspeculative and speculative algorithms, respectively, four and three steps. Besides the obvious benefits in terms of cost, resilience and management complexity—fewer replicas to tolerate a certain number of faults—our algorithms are simpler than previous ones, being closer to crash fault-tolerant replication algorithms. The performance evaluation shows that, even with the trusted component access overhead, they can have better throughput than Castro and Liskov's PBFT, and better latency in networks with nonnegligible communication delays.","Title: N-party BAR transfer\nYear: 2011\n\nAbstract: We introduce the N-party BAR transfer problem that consists in reliably transferring arbitrarily large data from a set of N producers to a set of N consumers in the BAR model, i.e., in the presence of Byzantine, Altruistic, and Rational participants. The problem considers the existence of a trusted observer that gathers evidence to testify that the producers and consumers have participated in the transfer. We present an algorithm that solves the problem for N≥2f+1, where f is the maximum number of Byzantine processes in each of the producer and consumer sets. We do not impose limits on the number of Rational participants, although they can deviate from the algorithm to improve their utility. We show that our algorithm provides a Nash equilibrium.","Title: Byzantine consensus in asynchronous message-passing systems: a survey\nYear: 2011\n\nAbstract: Consensus is a classical distributed systems problem with both theoretical and practical interest. Asynchronous Byzantine consensus is currently at the core of some solutions for the implementation of highly-resilient computing services. This paper surveys Byzantine consensus in message-passing distributed systems, by presenting the main theoretical results in the area, the main classes of algorithms and by discussing important issues like the performance and resilience of these algorithms.","Title: The CRUTIAL reference critical information infrastructure architecture: a blueprint\nYear: 2008\n\nAbstract: Critical infrastructures have evolved over the past decades to become largely computerised and interconnected all over the world. This generated the problem of achieving resilience of Critical Information Infrastructures (CII) against computer-borne attacks and severe faults, similar to those observed in the internet. Governments and industry have been pushing an immense research effort in information and systems security, but we believe the complexity of the problem prevents it from being solved using classical security methods. This paper focuses on the computer systems behind electrical utility infrastructures. It proposes the blueprint of a distributed systems architecture that we believe may come to be useful as a reference for modern CII in general. The architecture is instantiatedwithasetofclassesoftechniquesandalgorithms,basedonparadigms providing resilience to faults and attacks in an automatic way.","Title: GRIDTS: A New Approach for Fault-Tolerant Scheduling in Grid Computing\nYear: 2007\n\nAbstract: This paper proposes GRIDTS, a grid infrastructure in which the resources select the tasks they execute, on the contrary to traditional infrastructures where schedulers find resources for the tasks. This solution allows scheduling decisions to be made with up-to-date information about the resources, which is difficult in the traditional infrastructures. Moreover, GRIDTS provides fault-tolerant scheduling by combining a set of fault tolerance techniques to cope with crash faults in components of the system. The solution is mainly based a triple space, which supports the scheduling and also provides support for the fault tolerance mechanisms.","Title: Byzantine Fault-Tolerant Consensus in Wireless Ad Hoc Networks\nYear: 2013\n\nAbstract: Wireless ad hoc networks, due to their inherent unreliability, pose significant challenges to the task of achieving tight coordination among nodes. The failure of some nodes and momentary breakdown of communications, either of accidental or malicious nature, should not result in the failure of the entire system. This paper presents an asynchronous Byzantine consensus protocol--called Turquois--specifically designed for resource-constrained wireless ad hoc networks. The key to its efficiency is the fact that it tolerates dynamic message omissions, which allows an efficient utilization of the wireless broadcasting medium. The protocol also refrains from computationally expensive public-key cryptographic during its normal operation. The protocol is safe despite the arbitrary failure of $(f","Title: Brief announcement: decoupled quorum-based byzantine-resilient coordination in open distributed systems\nYear: 2006\n\nAbstract: The tuple space coordination model, originally introduced in the Linda programming language [2], uses a shared memory object called a tuple space to support coordination that is decoupled both in time – processes do not have to be active at the same time – and space – processes do not need to know each others' addresses. The tuple space can be considered to be a kind of storage that stores tuples, i.e. finite sequences of values. The operations supported are essentially three: inserting a tuple in the space, reading a tuple from the space and removing a tuple from the space.","Title: Decoupled Quorum-Based Byzantine-Resilient Coordination in Open Distributed Systems\nYear: 2007\n\nAbstract: Open distributed systems are typically composed by an unknown number of processes running in heterogeneous hosts. Their communication often requires tolerance to temporary disconnections and security against malicious actions. Tuple spaces are a well-known coordination model for this sort of systems. They can support communication that is decoupled both in time and space. There are currently several implementations of distributed fault-tolerant tuple spaces but they are not Byzantine-resilient, i.e., they do not provide a correct service if some replicas are attacked and start to misbehave. This paper presents an efficient implementation of LBTS, a linearizable Byzantine fault-tolerant tuple space. LBTS uses a novel Byzantine quorum systems replication technique in which most operations are implemented by quorum protocols while stronger operations are implemented by more expensive protocols based on consensus. LBTS is linearizable and wait-free, showing interesting performance gains when compared to a similar construction based on state machine replication.","Title: Using Attack Injection to Discover New Vulnerabilities\nYear: 2006\n\nAbstract: Due to our increasing reliance on computer systems, security incidents and their causes are important problems that need to be addressed. To contribute to this objective, the paper describes a new tool for the discovery of security vulnerabilities on network connected servers. The AJECT tool uses a speci-cation of the server's communication protocol to automatically generate a large number of attacks accordingly to some prede-ned test classes. Then, while it performs these attacks through the network, it monitors the behavior of the server both from a client perspective and inside the target machine. The observation of an incorrect behavior indicates a successful attack and the potential existence of a vulnerability. To demonstrate the usefulness of this approach, a considerable number of experiments were carried out with several IMAP servers. The results show that AJECT can discover several kinds of vulnerabilities, including a previously unknown vulnerability.","Title: The Design of a COTSReal-Time Distributed Security Kernel\nYear: 2002\n\nAbstract: This paper describes the design of a security kernel called TTCB, which has innovative features. Firstly, it is a distributed sub-system with its own secure network. Secondly, the TTCB is real-time, that is, a synchronous subsystem capable of timely behavior. These two characteristics together are uncommon in security kernels. Thirdly, the TTCB can be implemented using only COTS components. We discuss essentially three things in this paper: (1) The TTCB is a simple component providing a small set of basic secure services. It aims at building a new style of protocols to achieve intrusion tolerance, which for the most part execute in insecure, arbitrary failure environments, and resort to the TTCB only in crucial parts of their operation. (2) Besides, the TTCB is a synchronous device supplying functions that may be an enabler of a new generation of timed secure protocols, until now known to be fragile due to attacks on timing assumptions. (3) Finally, we present a design methodology that establishes our hybrid failure assumptions in a well-founded manner. It helps us to achieve a robust design, despite using exclusively COTS components, with the advantage of allowing the security kernel to be easily deployed on widely used platforms.","Title: Resilient Intrusion Tolerance through Proactive and Reactive Recovery\nYear: 2007\n\nAbstract: Previous works have studied how to use proactive recovery to build intrusion-tolerant replicated systems that are resilient to any number of faults, as long as recoveries are faster than an upper-bound on fault production assumed at system deployment time. In this paper, we propose a complementary approach that combines proactive recovery with services that allow correct replicas to react and recover replicas that they detect or suspect to be compromised. One key feature of our proactive-reactive recovery approach is that, despite recoveries, it guarantees the availability of the minimum amount of system replicas necessary to sustain system's correct operation. We design a proactive-reactive recovery service based on a hybrid distributed system model and show, as a case study, how this service can effectively be used to augment the resilience of an intrusion-tolerant firewall adequate for the protection of critical infrastructures.","Title: An Efficient Byzantine-Resilient Tuple Space\nYear: 2009\n\nAbstract: Open distributed systems are typically composed by an unknown number of processes running in heterogeneous hosts. Their communication often requires tolerance to temporary disconnections and security against malicious actions. Tuple spaces are a well-known coordination model for this kind of systems. They can support communication that is decoupled both in time and space. There are currently several implementations of distributed fault-tolerant tuple spaces but they are not Byzantine-resilient, i.e., they do not provide a correct service if some replicas are attacked and start to misbehave. This paper presents an efficient implementation of a Linearizable Byzantine fault-tolerant Tuple Space (LBTS) that uses a novel Byzantine quorum systems replication technique in which most operations are implemented by quorum protocols while stronger operations are implemented by more expensive protocols based on consensus. LBTS is linearizable and wait-free, showing interesting performance gains when compared to a similar construction based on state machine replication.","Title: Automatic detection and correction of web application vulnerabilities using data mining to predict false positives\nYear: 2014\n\nAbstract: Web application security is an important problem in today's internet. A major cause of this status is that many programmers do not have adequate knowledge about secure coding, so they leave applications with vulnerabilities. An approach to solve this problem is to use source code static analysis to find these bugs, but these tools are known to report many false positives that make hard the task of correcting the application. This paper explores the use of a hybrid of methods to detect vulnerabilities with less false positives. After an initial step that uses taint analysis to flag candidate vulnerabilities, our approach uses data mining to predict the existence of false positives. This approach reaches a trade-off between two apparently opposite approaches: humans coding the knowledge about vulnerabilities (for taint analysis) versus automatically obtaining that knowledge (with machine learning, for data mining). Given this more precise form of detection, we do automatic code correction by inserting fixes in the source code. The approach was implemented in the WAP tool and an experimental evaluation was performed with a large set of open source PHP applications.","Title: Practical hardening of crash-tolerant systems\nYear: 2012\n\nAbstract: Recent failures of production systems have highlighted the importance of tolerating faults beyond crashes. The industry has so far addressed this problem by hardening crash-tolerant systems with ad hoc error detection checks, potentially overlooking critical fault scenarios. We propose a generic and principled hardening technique for Arbitrary State Corruption (ASC) faults, which specifically model the effects of realistic data corruptions on distributed processes. Hardening does not require the use of trusted components or the replication of the process over multiple physical servers. We implemented a wrapper library to transparently harden distributed processes. To exercise our library and evaluate our technique, we obtained ASC-tolerant versions of Paxos, of a subset of the ZooKeeper API, and of an eventually consistent storage by implementing crash-tolerant protocols and automatically hardening them using our library. Our evaluation shows that the throughput of our ASC-hardened state machine replication outperforms its Byzantine-tolerant counterpart by up to 70%.","Title: Worm-IT - A wormhole-based intrusion-tolerant group communication system\nYear: 2007\n\nAbstract: This paper presents Worm-IT, a new intrusion-tolerant group communication system with a membership service and a view-synchronous atomic multicast primitive. The system is intrusion-tolerant in the sense that it behaves correctly even if some nodes are corrupted and become malicious. It is based on a novel approach that enhances the environment with a special secure distributed component used by the protocols to execute securely a few crucial operations. Using this approach, we manage to bring together two important features: Worm-IT tolerates the maximum number of malicious members possible; it does not have to detect the failure of primary-members, a problem in previous intrusion-tolerant group communication systems.","Title: Spin One's Wheels? Byzantine Fault Tolerance with a Spinning Primary\nYear: 2009\n\nAbstract: Most Byzantine fault-tolerant state machine replication(BFT) algorithms have a primary replica that is in charge of ordering the clients requests. Recently it was shown that this dependence allows a faulty primary to degrade the performance of the system to a small fraction of what the environment allows. In this paper we present Spinning, a novel BFT algorithm that mitigates such performance attacks by changing the primary after every batch of pending requests is accepted for execution. This novel mode of operation deals with those attacks at a much lower cost than previous solutions, maintaining a throughput equal or better to the algorithm that is usually consider to be the baseline in the area, Castro and Liskov’s PBFT.","Title: Asynchronous Byzantine consensus with 2f+1 processes\nYear: 2010\n\nAbstract: Byzantine consensus in asynchronous message-passing systems has been shown to require at least 3f + 1 processes to be solvable in several system models (e.g., with failure detectors, partial synchrony or randomization). Recently a couple of solutions to implement Byzantine fault-tolerant state-machine replication using only 2f + 1 replicas have appeared. This reduction from 3f + 1 to 2f + 1 is possible with a hybrid system model, i.e., by extending the system model with trusted/trustworthy components that constrain the power of faulty processes to have certain behaviors. Despite these important results, the problem of solving Byzantine consensus with only 2f + 1 processes is still far from being well understood. In this paper we present a methodology to transform crash consensus algorithms into Byzantine consensus algorithms with different characteristics, with the assistance of a reliable broadcast primitive that requires trusted/trustworthy components to be implemented. We exemplify the methodology with two algorithms, one that uses failure detectors and one that is randomized. We also define a new flavor of consensus and use it to solve atomic broadcast, showing the practical interest of the transformations.","Title: DepSpace: a byzantine fault-tolerant coordination service\nYear: 2008\n\nAbstract: The tuple space coordination model is one of the most interesting coordination models for open distributed systems due to its space and time decoupling and its synchronization power. Several works have tried to improve the dependability of tuple spaces through the use of replication for fault tolerance and access control for security. However, many practical applications in the Internet require both fault tolerance and security. This paper describes the design and implementation of DepSpace, a Byzantine fault-tolerant coordination service that provides a tuple space abstraction. The service offered by DepSpace is secure, reliable and available as long as less than a third of service replicas are faulty. Moreover, the content-addressable confidentiality scheme developed for DepSpace bridges the gap between Byzantine fault-tolerant replication and confidentiality of replicated data and can be used in other systems that store critical data.","Title: 4th workshop on recent advances in intrusion-tolerant systems, WRAITS 2010\nYear: 2010\n\nAbstract: Design and operational vulnerabilities are accepted as inevitable in today's complex computer systems. The distributed and networked nature of the systems that are currently in use and being developed facilitate discovery and exploitation of these flaws in increasingly new and easier ways. Intrusion Tolerance acknowledges that it is impossible to completely prevent attacks and intrusions, and that it is often impossible to accurately detect the act of intrusion and stop it early enough. Intrusion Tolerance research therefore aims to develop technologies that enable computer systems to continue to operate correctly despite attacks, and deny the attacker/intruder the success they seek. For instance, an intrusion-tolerant system may suffer partial loss of service or resources due to the attack, but it will continue to provide critical services in a degraded mode or trigger automatic mechanisms to regain and recover the compromised services and resources. Similar goals are being pursued in Survivability, Byzantine Fault Tolerance, Self-regenerative and Autonomic Systems.","Title: MITRA: byzantine fault-tolerant middleware for transaction processing on replicated databases\nYear: 2014\n\nAbstract: Replication is often considered a cost-effective solution for building dependable systems with off-the-shelf hardware. Replication software is usually designed to tolerate crash faults, but Byzantine (or arbitrary) faults such as software bugs are well-known to affect transactional database management systems (DBMSs) as many other classes of software. Despite the maturity of replication technology, Byzantine fault-tolerant replication of databases remains a challenging problem. The paper presents MITRA, a middleware for replicating DBMSs and making them tolerant to Byzantine faults. MITRA is designed to offer transparent replication of off-theshelf DBMSs with replicas from different vendors.","Title: Finite Memory: A Vulnerability of Intrusion-Tolerant Systems\nYear: 2008\n\nAbstract: In environments like the Internet, faults follow unusual patterns, dictated by the combination of malicious attacks with accidental faults such as long communication delays caused by temporary network partitions. In this scenario, attackers can force buffer overflows in order to leave the system in an inconsistent state or to prevent it from doing progress, causing a denial of service. This paper is about the effects that finite memory has on intrusion-tolerant protocols and systems. We present the problem and propose a generic mitigation technique based on repair nodes that reduces the buffer space requirements. An experimental evaluation of the buffer usage with and without this technique is presented, allowing to assess in practice the effects of finite memory in a real, albeit simple, intrusion-tolerant system.","Title: An Infrastructure for Adaptive Fault Tolerance on FT-CORBA\nYear: 2006\n\nAbstract: The fault tolerance provided by FT-CORBA is basically static, that is, once the fault tolerance properties of a group of replicated processes are defined, they cannot be modified in runtime. A support for dynamic reconfiguration of the replication would be highly advantageous since it would allow the implementation of mechanisms for adaptive fault tolerance, enabling FT-CORBA to adapt to the changes that can occur in the execution environment. In this paper, we propose a set of extensions to the FT-CORBA infrastructure in the form of interfaces and object service implementations, enabling it to support dynamic reconfiguration of the replication.","Title: Intrusion Tolerance in Wireless Environments: An Experimental Evaluation\nYear: 2007\n\nAbstract: This paper presents a study on the performance of intrusion-tolerant protocols in wireless LANs. The protocols are evaluated in several different environmental settings, and also within the context of a car platooning application for distributed cruise control. The experimental evaluation reveals how performance is affected by the various environmental parameters such as the wireless standard, group size, and network topology. The distributed cruise control application demonstrates the practicability of such protocols, even when subjected to malicious faults.","Title: The CRUTIAL Architecture for Critical Information Infrastructures\nYear: 2007\n\nAbstract: In this chapter we discuss the susceptibility of critical information infrastructures to computer-borne attacks and faults, mainly due to their largely computerized nature, and to the pervasive interconnection of systems all over the world. We discuss how to overcome these problems and achieve resilience of critical information infrastructures, through adequate architectural constructs. The architecture we propose is generic and may come to be useful as a reference for modern critical information infrastructures. We discuss four main aspects: trusted components which induce prevention; middleware devices that achieve runtime automatic tolerance and protection; trustworthiness monitoring mechanisms detecting and adapting to non-predicted situations; organization-level security policies and access control models capable of securing global information flows.","Title: Intrusion Tolerant Services Through Virtualization: A Shared Memory Approach\nYear: 2010\n\nAbstract: Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distributed applications has been made in recent years. These solutions are designed to make the applications resistant to successful attacks against the system, thereby making services tolerant to intrusions. Recently, some of these studies have considered the use of virtual machines for building a trusted computing environment. This paper presents SMIT (Shared Memory based Intrusion Tolerance), an architecture for Intrusion Tolerance using virtual machines that benefits from a shared memory to simplify the consensus protocol.","Title: Randomized Intrusion-Tolerant Asynchronous Services\nYear: 2006\n\nAbstract: Randomized agreement protocols have been around for more than two decades. Often assumed to be inefficient due to their high expected communication and time complexities, they have remained largely overlooked by the community-at-large as a valid solution for the deployment of fault-tolerant distributed systems. This paper aims to demonstrate that randomization can be a very competitive approach even in hostile environments where arbitrary faults can occur. A stack of randomized intrusion-tolerant protocols is described and its performance evaluated under different faultloads. The stack provides a set of relevant services ranging from basic communication primitives up to atomic broadcast. The experimental evaluation shows that the protocols are efficient and no performance reduction is observed under certain Byzantine faults.","Title: EBAWA: Efficient Byzantine Agreement for Wide-Area Networks\nYear: 2010\n\nAbstract: The popularity of wide-area computer services has generated a compelling need for efficient algorithms that provide high reliability. Byzantine fault-tolerant (BFT) algorithms can be used with this purpose because they allow replicated systems to continue to provide a correct service even when some of their replicas fail arbitrarily, either accidentally or due to malicious faults. Current BFT algorithms perform well on LANs but when the replicas are distributed geographically their performance is affected by the lower bandwidth and the higher and more heterogeneous network latencies. This paper proposes and evaluates a novel BFT algorithm for WANs that requires fewer communication steps, fewer replicas and has better throughput and latency than others in the literature. The paper presents an extensive evaluation of the algorithm’s performance in several settings and conditions: in a LAN, in real and emulated WANs, with clients close to servers and dispersed geographically, with similar and different communication latencies between clients and servers.","Title: From Consensus to Atomic Broadcast: Time-Free Byzantine-Resistant Protocols without Signatures\nYear: 2006\n\nAbstract: This paper proposes a stack of three Byzantine-resistant protocols aimed to be used in practical distributed systems: multi-valued consensus, vector consensus and atomic broadcast. These protocols are designed as successive transformations from one to another. The first protocol, multi-valued consensus, is implemented on top of a randomized binary consensus and a reliable broadcast protocol. The protocols share a set of important structural properties. First, they do not use digital signatures constructed with public-key cryptography, a well-known performance bottleneck in this kind of protocols. Second, they are time-free, i.e. they make no synchrony assumptions, since these assumptions are often vulnerable to subtle but effective attacks. Third, they are completely decentralized, thus avoiding the cost of detecting corrupt leaders. Fourth, they have optimal resilience, i.e. they tolerate the failure of f = ⌊(n-1)/3⌋ out of a total of n processes. In terms of time complexity, the multi-valued consensus protocol terminates in a constant expected number of rounds, while the vector consensus and atomic broadcast protocols have O(f) complexity. The paper also proves the equivalence between multi-valued consensus and atomic broadcast in the Byzantine failure model without signatures. A similar proof is given for the equivalence between multi-valued consensus and vector consensus. These two results have theoretical relevance since they show once more that consensus is a fundamental problem in distributed systems.","Title: Low complexity Byzantine-resilient consensus\nYear: 2005\n\nAbstract: The application of the tolerance paradigm to security - intrusion tolerance - has been raising a reasonable amount of attention in the dependability and security communities. In this paper we present a novel approach to intrusion tolerence. The idea is to use privileged components - generically designated by wormholes - to support the execution of intrusion-tolerant protocols, often called Byzantine-resilient in the literature.The paper introduces the design of wormhole-aware intrusion-tolerant protocols using a classical distributed systems problem: consensus. The system where the consensus protocol runs is mostly asynchronous and can fail in an arbitrary way, except for the wormhole, which is secure and synchronous. Using the wormhole to execute a few critical steps, the protocol manages to have a low time complexity: in the best case, it runs in two rounds, even if some processes are malicious. The protocol also shows how often theoretical partial synchrony assumptions can be substantiated in practical distributed systems. The paper shows the significance of the TTCB as an engineering paradigm, since the protocol manages to be simple when compared with other protocols in the literature.","Title: Highly Available Intrusion-Tolerant Services with Proactive-Reactive Recovery\nYear: 2010\n\nAbstract: In the past, some research has been done on how to use proactive recovery to build intrusion-tolerant replicated systems that are resilient to any number of faults, as long as recoveries are faster than an upper bound on fault production assumed at system deployment time. In this paper, we propose a complementary approach that enhances proactive recovery with additional reactive mechanisms giving correct replicas the capability of recovering other replicas that are detected or suspected of being compromised. One key feature of our proactive-reactive recovery approach is that, despite recoveries, it guarantees the availability of a minimum number of system replicas necessary to sustain correct operation of the system. We design a proactive-reactive recovery service based on a hybrid distributed system model and show, as a case study, how this service can effectively be used to increase the resilience of an intrusion-tolerant firewall adequate for the protection of critical infrastructures.","Title: Byzantine Fault-Tolerant MapReduce: Faults are Not Just Crashes\nYear: 2011\n\nAbstract: MapReduce is often used to run critical jobs such as scientific data analysis. However, evidence in the literature shows that arbitrary faults do occur and can probably corrupt the results of MapReduce jobs. MapReduce runtimes like Hadoop tolerate crash faults, but not arbitrary or Byzantine faults. We present a MapReduce algorithm and prototype that tolerate these faults. An experimental evaluation shows that the execution of a job with our algorithms uses twice the resources of the original Hadoop, instead of the 3 or 4 times more that would be achieved with the direct application of common Byzantine fault-tolerance paradigms. We believe this cost is acceptable for critical applications that require that level of fault tolerance.","Title: Randomization can be a healer: consensus with dynamic omission failures\nYear: 2011\n\nAbstract: Wireless ad-hoc networks are being increasingly used in diverse contexts, ranging from casual meetings to disaster recovery operations. A promising approach is to model these networks as distributed systems prone to dynamic communication failures. This captures transitory disconnections in communication due to phenomena like interference and collisions, and permits an efficient use of the wireless broadcasting medium. This model, however, is bound by the impossibility result of Santoro and Widmayer, which states that, even with strong synchrony assumptions, there is no deterministic solution to any non-trivial form of agreement if n - 1 or more messages can be lost per communication round in a system with n processes. In this paper we propose a novel way to circumvent this impossibility result by employing randomization. We present a consensus protocol that ensures safety in the presence of an unrestricted number of omission faults, and guarantees progress in rounds where such faults are bounded by f ≤ ⌈n/2⌉(n-k)+k - 2, where k is the number of processes required to decide, eventually assuring termination with probability 1.","Title: Clouds-of-Clouds for Dependability and Security: Geo-replication Meets the Cloud.\nYear: 2013\n\nAbstract: The complexity of large cloud offerings makes it extremely hard to guarantee their dependability and security. This paper extracts lessons from some years of research on the notion of using several clouds instead of a single one-with the objective of achieving high dependability and security. We show that using such clouds-of-clouds it is possible for services to continue to operate correctly despite dependability and security issues in a subset of the clouds. We show this approach with three cases: clouds-of-clouds for storage with the DepSky system; cloud-of- clouds for data processing with Map Reduce; the execution of arbitrary services in clouds-of-clouds with the EBAWA algorithm.","Title: CRUTIAL: the blueprint of a reference critical information infrastructure architecture\nYear: 2006\n\nAbstract: In the past few decades, critical infrastructures have become largely computerised and interconnected all over the world. This generated the problem of achieving resilience of critical information infrastructures against computer-borne attacks and severe faults. Governments and industry have been pushing an immense research effort in information and systems security, but we believe the complexity of the problem prevents it from being solved using classical security methods. The paper focuses on the computer systems behind electrical utility infrastructures. It proposes the blueprint of a distributed systems architecture that we believe may come to be useful as a reference for modern critical information infrastructures in general. The architecture is instantiated with a set of classes of techniques and algorithms, based on paradigms providing resilience to faults and attacks in an automatic way.","Title: Exploiting Tuple Spaces to Provide Fault-Tolerant Scheduling on Computational Grids\nYear: 2007\n\nAbstract: In this paper we present our vision of establishing self-coordination as the dominant paradigm of operation of future embedded computing environments. This vision is looked at from three different points of view. First of all techniques to model self-coordinating ...","Title: Lucy in the sky without diamonds: Stealing confidential data in the cloud\nYear: 2011\n\nAbstract: Cloud Computing is a recent paradigm that is creating high expectations about benefits such as the pay-per-use model and elasticity of resources. However, with this optimism come also concerns about security. In a public cloud, the user's data storage and processing is no longer done inside its premises, but in data centers owned and administrated by the cloud provider. This may be a concern for organizations that deal with critical data, such as medical records. We show that a malicious insider can steal confidential data of the cloud user, so the user is mostly left with trusting the cloud provider. The paper achieves this goal by showing a set of attacks that demonstrate how a malicious insider can easily obtain passwords, cryptographic keys, files and other confidential data. Additionally, the paper shows that recent research results that might be useful to protect data in the cloud, are still not enough to deal with the problem. The paper is a call to arms for research in the topic.","Title: On Byzantine generals with alternative plans\nYear: 2008\n\nAbstract: This paper proposes a variation of the Byzantine generals problem (or Byzantine consensus). Each general has a set of good plans and a set of bad plans. The problem is to make all loyal generals agree on a good plan proposed by a loyal general, and never on a bad plan.","Title: Byzantine Fault-Tolerant Transaction Processing for Replicated Databases\nYear: 2011\n\nAbstract: Transaction commit is a problem much investigated, both in the databases and systems communities, from the theoretical and practical sides. We present a modular approach to solve this problem in the context of database replication on environments that are subject to Byzantine faults. Our protocol builds on a total order multicast abstraction and is proven to satisfy a set of safety and liveness properties. On the contrary of previous solutions in the literature, it assures strong consistency for transactions, tolerates Byzantine clients and does not need centralized control or multi-version databases. We present an evaluation of a prototype of the system.","Title: On the efficiency of durable state machine replication\nYear: 2013\n\nAbstract: State Machine Replication (SMR) is a fundamental technique for ensuring the dependability of critical services in modern internet-scale infrastructures. SMR alone does not protect from full crashes, and thus in practice it is employed together with secondary storage to ensure the durability of the data managed by these services. In this work we show that the classical durability enforcing mechanisms - logging, checkpointing, state transfer - can have a high impact on the performance of SMR-based services even if SSDs are used instead of disks. To alleviate this impact, we propose three techniques that can be used in a transparent manner, i.e., without modifying the SMR programming model or requiring extra resources: parallel logging, sequential checkpointing, and collaborative state transfer. We show the benefits of these techniques experimentally by implementing them in an open-source replication library, and evaluating them in the context of a consistent key-value store and a coordination service.","Title: The Crutial Way of Critical Infrastructure Protection\nYear: 2008\n\nAbstract: Critical infrastructures such as the power grid are essentially physical processes controlled by computers connected by networks. They're usually as vulnerable as any other interconnected computer system, but their failure has a high socioeconomic impact. The Critical Utility Infrastructural Resilience (Crutial) project designed an information switch (CIS) to protect these infrastructures. These devices help ensure that incoming and outgoing traffic satisfies the security policy of an infrastructure in face of cyberattacks. A CIS isn't a firewall, but a distributed protection device based on a sophisticated access control model. Furthermore, a CIS is intrusion-tolerant and self-healing, seeking perpetual unattended correct operation.","Title: Sharing Memory between Byzantine Processes using Policy-Enforced Tuple Spaces\nYear: 2006\n\nAbstract: The Java messaging service (JMS) is a means to organize communication among distributed applications according to the publish/subscribe principle. If the subscribers install filter rules on the JMS server, JMS can be used as a message routing platform, ...","Title: A multi-objective routing algorithm for Wireless Multimedia Sensor Networks\nYear: 2015\n\nAbstract: Graphical abstractDisplay Omitted HighlightsA new multi-objective approach for the routing problem in Wireless Multimedia Sensor Networks (WMSNs) is proposed.Classical approximations optimize a single objective or Quality of Service (QoS) parameter.Classical approximations do not take into account the conflicting nature of QoS parameters which leads to sub-optimal solutions.The proposed approach takes into account multiple QoS requirements such as delay and the Expected Transmission Count (ETX).The case studies applying the proposed approach shows clear improvements on the QoS routing solutions. In this paper, a new multi-objective approach for the routing problem in Wireless Multimedia Sensor Networks (WMSNs) is proposed. It takes into account Quality of Service (QoS) requirements such as delay and the Expected Transmission Count (ETX). Classical approximations optimize a single objective or QoS parameter, not taking into account the conflicting nature of these parameters which leads to sub-optimal solutions. The case studies applying the proposed approach show clear improvements on the QoS routing solutions. For example, in terms of delay, the approximate mean improvement ratios obtained for scenarios 1 and 2 were of 15 and 28 times, respectively.","Title: Efficient Byzantine-resilient reliable multicast on a hybrid failure model\nYear: 2002\n\nAbstract: The paper presents a new reliable multicast protocol that tolerates arbitrary faults, including Byzantine faults. This protocol is developed using a novel way of designing secureprotocols which is based on a well-founded hybrid failure model. Despite our claim of arbitrary failure resilience, the protocol needs not necessarily incur the cost of \"Byzantine agreement\", in number of participants and round/message complexity. It can rely on the existence of a simple distributed security kernel 驴 the TTCB 驴 where the participants only execute crucial parts of the protocol operation, under the protection of a crash failure model. Otherwise, participants follow an arbitrary failure model.The TTCB provides only a few basic services, which allow our protocol to have an efficiency similar to that of accidental fault-tolerant protocols: for f faults, our protocol requires f+2 processes, instead of 3f+1 in Byzantine systems. Besides, the TTCB (which is synchronous) allows secure operation of timed protocols, despite the unpredictable time behavior of the environment (possibly due to attacks on timing assumptions).","Title: How to tolerate half less one Byzantine nodes in practical distributed systems\nYear: 2004\n\nAbstract: The application of dependability concepts and techniques to the design of secure distributed systems is raising a considerable amount of interest in both communities under the designation of intrusion tolerance. However, practical intrusion-tolerant replicated systems based on the state machine approach (SMA) can handle at most f Byzantine components out of a total of n = 3f + 1, which is the maximum resilience in asynchronous systems. This paper extends the normal asynchronous system with a special distributed oracle called TTCB. Using this extended system we manage to implement an intrusion-tolerant service based on the SMA with only 2f + 1 replicas. Albeit a few other papers in the literature present intrusion-tolerant services with this approach, this is the first time the number of replicas is reduced from 3f + 1 to 2f + 1. Another interesting characteristic of the described service is a low time complexity.","Title: Solving vector consensus with a wormhole\nYear: 2005\n\nAbstract: This paper presents a solution to the vector consensus problem for Byzantine asynchronous systems augmented with wormholes. Wormholes prefigure a hybrid distributed system model, embodying the notion of an enhanced part of the system with \"good驴 properties otherwise not guaranteed by the \"normal驴 weak environment. A protocol built for this type of system runs in the asynchronous part, where f out of n \\geq 3f+1 processes might be corrupted by malicious adversaries. However, sporadically, processes can rely on the services provided by the wormhole for the correct execution of simple operations. One of the nice features of this setting is that it is possible to keep the protocol completely time-free and, in addition, to circumvent the FLP impossibility result by hiding all time-related assumptions in the wormhole. Furthermore, from a performance perspective, it leads to the design of a protocol with a good time complexity.","Title: Experimental Comparison of Local and Shared Coin Randomized Consensus Protocols\nYear: 2006\n\nAbstract: The paper presents a comparative performance study of the two main classes of randomized binary consensus protocols: a local coin protocol, with an expected high communication complexity and cheap symmetric cryptography, and a shared coin protocol, with an expected low communication complexity and expensive asymmetric cryptography. The experimental evaluation was conducted on a LAN environment, by varying several system parameters, such as the fault types and number of processes. The analysis shows that there is a significant gap between the theoretical and the practical performance results of these protocols, and provides an important insight into what actually happens during their execution.","Title: Sharing Memory between Byzantine Processes Using Policy-Enforced Tuple Spaces\nYear: 2009\n\nAbstract: Despite the large amount of Byzantine fault-tolerant algorithms for message-passing systems designed through the years, only recently algorithms for the coordination of processes subject to Byzantine failures using shared memory have appeared. This paper presents a new computing model in which shared memory objects are protected by fine-grained access policies, and a new shared memory object, the policy-enforced augmented tuple space (PEATS). We show the benefits of this model by providing simple and efficient consensus algorithms. These algorithms are much simpler and requires less shared memory operations, using also less memory bits than previous algorithms based on access control lists ACLs and sticky bits. We also prove that PEATS objects are universal, i.e., that they can be used to implement any other shared memory object, and present lock-free and wait-free universal constructions.","Title: 3rd Workshop on Recent Advances on Intrusion-Tolerant Systems WRAITS 2009\nYear: 2009\n\nAbstract: The 3rd Workshop on Recent Advances in Intrusion- Tolerant Systems, held in conjunction with DSN 2009, aims to provide the researchers and practitioners an intimate venue to discuss and collaborate on ground-breaking new ideas and fresh results.","Title: Monitoring of bedridden patients: Development of a fall detection tool\nYear: 2013\n\nAbstract: Falls of patients are an important issue in hospitals, it causes severe injuries to the patients, increases hospitalization time and treatment costs. The detection of a fall, in time, provides faster rescue to the patient, preventing more serious injuries, as well as saving nursing time. The MovinSense® is an electronic device designed for monitoring patients to prevent pressure sores, and the main goal of this work was to develop a new tool for this device, with the purpose of detecting if the patient has fallen from the hospital bed, without changing any of the device original features. Experiments for gathering data samples of inertial signals of falling from the bed were obtained using the device. For fall detection a sensitivity of 72% and specificity of 100% were reached. Another algorithm was developed to detect if the patient got out of his/her bed.","Title: Monitoring of bedridden patients: Development of a fall detection tool\nYear: 2013\n\nAbstract: Falls of patients are an important issue in hospitals, it causes severe injuries to the patients, increases hospitalization time and treatment costs. The detection of a fall, in time, provides faster rescue to the patient, preventing more serious injuries, as well as saving nursing time. The MovinSense® is an electronic device designed for monitoring patients to prevent pressure sores, and the main goal of this work was to develop a new tool for this device, with the purpose of detecting if the patient has fallen from the hospital bed, without changing any of the device original features. Experiments for gathering data samples of inertial signals of falling from the bed were obtained using the device. For fall detection a sensitivity of 72% and specificity of 100% were reached. Another algorithm was developed to detect if the patient got out of his/her bed.","Title: Monitoring of bedridden patients: Development of a fall detection tool\nYear: 2013\n\nAbstract: Falls of patients are an important issue in hospitals, it causes severe injuries to the patients, increases hospitalization time and treatment costs. The detection of a fall, in time, provides faster rescue to the patient, preventing more serious injuries, as well as saving nursing time. The MovinSense® is an electronic device designed for monitoring patients to prevent pressure sores, and the main goal of this work was to develop a new tool for this device, with the purpose of detecting if the patient has fallen from the hospital bed, without changing any of the device original features. Experiments for gathering data samples of inertial signals of falling from the bed were obtained using the device. For fall detection a sensitivity of 72% and specificity of 100% were reached. Another algorithm was developed to detect if the patient got out of his/her bed.","Title: Byzantine fault-tolerant state machine replication with twin virtual machines\nYear: 2013\n\nAbstract: The reliability and availability of distributed services can be ensured using replication. We present an architecture and an algorithm for Byzantine fault-tolerant state machine replication. We explore the benefits of virtualization to reliably detect and tolerate faulty replicas, allowing the transformation of Byzantine faults into omission faults. Our approach reduces the total number of physical replicas from 3f+1 to 2f+1. It is based on the concept of twin virtual machines, which involves having two virtual machines in each physical host, each one acting as failure detector of the other.","Title: The Final Frontier: Confidentiality and Privacy in the Cloud\nYear: 2011\n\nAbstract: The boundary between the trusted inside and the untrusted outside blurs when a company adopts cloud computing. The organization's applications-and data-are no longer onsite, fundamentally changing the definition of a malicious insider.","Title: On the Performance of Byzantine Fault-Tolerant MapReduce\nYear: 2013\n\nAbstract: MapReduce is often used for critical data processing, e.g., in the context of scientific or financial simulation. However, there is evidence in the literature that there are arbitrary (or Byzantine) faults that may corrupt the results of MapReduce without being detected. We present a Byzantine fault-tolerant MapReduce framework that can run in two modes: nonspeculative and speculative. We thoroughly evaluate experimentally the performance of these two versions of the framework, showing that they use around twice more resources than Hadoop MapReduce, instead of the three times more of alternative solutions. We believe this cost is acceptable for many critical applications.","Title: Turquois: Byzantine consensus in wireless ad hoc networks\nYear: 2010\n\nAbstract: The operation of wireless ad hoc networks is intrinsically tied to the ability of nodes to coordinate their actions in a dependable and efficient manner. The failure of some nodes and momentary breakdown of communications, either of accidental or malicious nature, should not result in the failure of the entire system. This paper presents Turquois - an intrusion-tolerant consensus protocol specifically de- signed for resource-constrained wireless ad hoc networks. Turquois allows an efficient utilization of the broadcasting medium, avoids synchrony assumptions, and refrains from public-key cryptography during its normal operation. The protocol is safe despite the arbitrary failure of f < n 3 pro- cesses from a total of n processes, and unrestricted mes- sage omissions. The protocol was prototyped and subject to a comparative performance evaluation against two well- known intrusion-tolerant consensus protocols. The results show that, as the system scales, Turquois outperforms the other protocols by more than an order of magnitude.","Title: Big Data Analytics for Detecting Host Misbehavior in Large Logs\nYear: 2015\n\nAbstract: The management of complex network infrastructures continues to be a difficult endeavor today. These infrastructures can contain a huge number of devices that may misbehave in unpredictable ways. Many of these devices keep logs that contain valuable information about the infrastructures' security, reliability, and performance. However, extracting information from that data is far from trivial. The paper presents a novel approach to assess the security of such an infrastructure using its logs, inspired on data from a real telecommunications network. We use machine learning and data mining techniques to analyze the data and semi-automatically discover misbehaving hosts, without having to instruct the system about how hosts misbehave.","Title: Anticipating Requests to Improve Performance and Reduce Costs in Cloud Storage\nYear: 2015\n\nAbstract: Clouds are a suitable place to store data with scalability and financial flexibility. However, it is difficult to ensure the reliability of the data stored in a cloud. Byzantine fault tolerance can improve reliability, but at a high cost. This paper presents a technique that anticipates requests in order to reduce that cost. We show that this technique improves the performance in comparison with related works and maintains the desired data reliability.","Title: Betweenness centrality in Delay Tolerant Networks: A survey\nYear: 2015\n\nAbstract: Dynamic networks, in particular Delay Tolerant Networks (DTNs), are characterized by a lack of end-to-end paths at any given instant. Because of that, DTN routing protocols employ a store-carry-and-forward approach, holding messages until a suitable node to forward them is found. But, the selection of the best forwarding node poses a considerable challenge. Additional network information (static or dynamic) can be leveraged to aid routing protocols in this troublesome task. One could use centrality metrics, therefore providing means to differentiate the importance of nodes in the network. Among these metrics, betweenness centrality is one of the most prominent, as it measures the degree to which a vertex is in a position of brokerage by summing up the fraction of shortest paths between other pairs of vertices passing through it. So, in this paper, betweenness centrality is surveyed, that is, its definitions and variants in static and dynamic networks are presented. Also, a survey of standard algorithms used to compute the metric (exact and approximate) is presented. Finally, a survey and a discussion on how DTN routing protocols make use of the betweenness centrality metric and algorithms to aid message forwarding is also presented.","Title: Detecting and Removing Web Application Vulnerabilities with Static Analysis and Data Mining.\nYear: 2016\n\nAbstract: Although a large research effort on web application security has been going on for more than a decade, the security of web applications continues to be a challenging problem. An important part of that problem derives from vulnerable source code, often written in unsafe languages like PHP. Source code static analysis tools are a solution to find vulnerabilities, but they tend to generate false posi...","Title: Shuttle: Intrusion Recovery for PaaS\nYear: 2015\n\nAbstract: The number of applications being deployed using the Platform as a Service (PaaS) cloud computing model is increasing. Despite the security controls implemented by cloud service providers, we expect intrusions to strike such applications. We present Shuttle, a novel intrusion recovery service. Shuttle recovers from intrusions in applications deployed in PaaS platforms. Our approach allows undoing changes to the state of PaaS applications due to intrusions, without loosing the effect of legitimate operations performed after the intrusions take place. We combine a record-and-replay approach with the elasticity provided by cloud offerings to recover applications deployed on various instances and backed by distributed databases. The service loads a database snapshot taken before the intrusion and replays subsequent requests, as much in parallel as possible, while continuing to execute incoming requests. We present an experimental evaluation of Shuttle on Amazon Web Services. We show Shuttle can replay 1 million requests in 10 minutes and that it can duplicate the number of requests replayed per second by increasing the number of application servers from 1 to 3.","Title: Hacking the DBMS to Prevent Injection Attacks.\nYear: 2016\n\nAbstract: After more than a decade of research, web application security continues to be a challenge and the backend database the most appetizing target. The paper proposes preventing injection attacks against the database management system (DBMS) behind web applications by embedding protections in the DBMS itself. The motivation is twofold. First, the approach of embedding protections in operating systems and applications running on top of them has been effective to protect this software. Second, there is a semantic mismatch between how SQL queries are believed to be executed by the DBMS and how they are actually executed, leading to subtle vulnerabilities in prevention mechanisms. The approach -- SEPTIC -- was implemented in MySQL and evaluated experimentally with web applications written in PHP and Java/Spring. In the evaluation SEPTIC has shown neither false negatives nor false positives, on the contrary of alternative approaches, causing also a low performance overhead in the order of 2.2%.","Title: Greft: Arbitrary Fault-Tolerant Distributed Graph Processing\nYear: 2015\n\nAbstract: Many large-scale computing problems can be modeled as graphs. Example areas include the web, social networks, and biological systems. The increasing sizes of datasets has led to the creation of various distributed large scale graph processing systems, e.g., Google Pregel. Although these systems tolerate crash faults, the literature suggests they are vulnerable to a wider range of accidental arbitrary faults (also called Byzantine faults). In this paper we present an algorithm and a prototype of a distributed large-scale graph processing system that can tolerate arbitrary faults. The prototype is based on GPS, an open source implementation of Pregel. Experimental results of the prototype in Amazon AWS are presented, showing that it uses only twice the resources of the original implementation, instead of 3-4 times as usual in Byzantine fault-tolerant systems. This cost may be acceptable for critical applications that require this level of fault tolerance.","Title: JITeR: Just-in-time application-layer routing.\nYear: 2016\n\nAbstract: The paper addresses the problem of providing message latency and reliability assurances for control traffic in wide-area IP networks. This is an important problem for cloud services and other geo-distributed information infrastructures that entail inter-datacenter real-time communication. We present the design and validation of JITeR (Just-In-Time Routing), an algorithm that timely routes messages at application-layer using overlay networking and multihoming, leveraging the natural redundancy of wide-area IP networks. We implemented a prototype of JITeR that we evaluated experimentally by placing nodes in several regions of Amazon EC2. We also present a scenario-based (geo-distributed utility network) evaluation comparing JITeR with alternative overlay/multihoming routing algorithms that shows that it provides better timeliness and reliability guarantees.","Title: Priority-Based State Machine Replication with PRaxos\nYear: 2016\n\nAbstract: State machine replication is a form of active replication commonly used to create fault-tolerant distributed services. In a nutshell, the approach consists in ensuring that a set of replicas receive and execute the same sequence of deterministic requests, returning the same results. This approach handles all requests evenly, but for some services it is important to consider that some requests have priority over others, i.e., that whenever two or more requests are ready to be executed, the one with higher priority is executed first. Paxos is perhaps the best known protocol to order requests in asynchronous environments, but Paxos has no notion of priority. In this paper we introduce the notion of priority-based state machine replication and modify Paxos to take request priorities into account. The proposed algorithm, PRaxos, works in three steps and satisfies Paxos' safety properties in asynchronous systems, while enforcing priorities when the system behaves synchronously.","Title: DEKANT: a static analysis tool that learns to detect web application vulnerabilities.\nYear: 2016\n\nAbstract: The state of web security remains troubling as web applications continue to be favorite targets of hackers. Static analysis tools are important mechanisms for programmers to deal with this problem as they search for vulnerabilities automatically in the application source code, allowing programmers to remove them. However, developing these tools requires explicitly coding knowledge about how to discover each kind of vulnerability. This paper presents a new approach in which static analysis tools learn to detect vulnerabilities automatically using machine learning. The approach uses a sequence model to learn to characterize vulnerabilities based on a set of annotated source code slices. This model takes into consideration the order in which the code elements appear and are executed in the slices. The model created can then be used as a static analysis tool to discover and identify vulnerabilities in source code. The approach was implemented in the DEKANT tool and evaluated experimentally with a set of open source PHP applications and WordPress plugins, finding 16 zero-day vulnerabilities.","Title: Equipping WAP with WEAPONS to Detect Vulnerabilities: Practical Experience Report\nYear: 2016\n\nAbstract: Although security starts to be taken into account during software development, the tendency for source code to contain vulnerabilities persists. Open source static analysis tools provide a sensible approach to mitigate this problem. However, these tools are programmed to detect a specific set of vulnerabilities and they are often difficult to extend to detect new ones. WAP is a recent popular open source tool that detects vulnerabilities in the source code of web applications written in PHP. The paper addresses the difficulty of extending these tools by proposing a modular and extensible version of the WAP tool, equipping it with \"weapons\" to detect (and correct) new vulnerability classes. The new version of the tool was evaluated with seven new vulnerability classes using web applications and plugins of the widely-adopted WordPress content management system. The experimental results show that this extensibility allows WAP to find many new (zero-day) vulnerabilities.","Title: DARSHANA: Detecting route hijacking for communication confidentiality\nYear: 2016\n\nAbstract: The Border Gateway Protocol (BGP) plays a critical role in the Internet providing connectivity to hosts across the world. Unfortunately, due to its limited security, attackers can hijack traffic by generating invalid routes. Some detection systems for route hijacking have been presented, but they require non-public information, high resources, or can easily be circumvented by attackers. We propose DARSHANA, a monitoring solution that detects route hijacking based solely on data-plane information, and has enough redundancy to prevent attacker countermeasures such as dropping of traceroute probes. DARSHANA uses active probing techniques that enable detection in near real-time. By using diverse methods, DARSHANA can still detect attacks even if the adversary manages to counter some techniques. We show that our solution allows effective detection of many hijacking attacks by emulating them using PlanetLab and Amazon AWS.","Title: vtTLS: A vulnerability-tolerant communication protocol\nYear: 2016\n\nAbstract: We present VTTLS, a vulnerability-tolerant communication protocol. There are often concerns about the strength of some of the encryption mechanisms used in SSL/TLS channels, with some regarded as insecure at some point in time. VTTLS is our solution to mitigate the problem of secure communication channels being vulnerable to attacks due to unexpected vulnerabilities in encryption mechanisms. It is based on diversity and redundancy of cryptographic mechanisms and certificates to provide a secure communication channel even when one or more mechanisms are vulnerable. VTTLS relies on a combination of k cipher suites. Even if k-1 cipher suites are insecure or vulnerable, VTTLS relies on the remaining cipher suites to maintain the channel secure. We evaluated the performance of VTTLS by comparing it to an OpenSSL channel.","Title: MACHETE: Multi-path communication for security\nYear: 2016\n\nAbstract: Communication through the Internet raises privacy and confidentiality concerns. Protocols such as HTTPS may be used to protect the communication, but occasionally vulnerabilities that may allow snooping on packet content are discovered. To address this issue, we present MACHETE, an application-layer multi-path communication mechanism that provides additional confidentiality by splitting data streams in different physical paths. MACHETE has to handle two challenges: sending packets over different paths when Internet's routing imposes a single path between pairs of network interfaces; splitting streams of data sent over TCP connections. MACHETE is the first to exploit MultiPath TCP (MPTCP) for security purposes. It leverages overlay networks and multihoming to handle the first challenge and MPTCP to handle the second. MACHETE establishes an overlay network and scatters the data over the available paths, thus reducing the effectiveness of snooping attacks. Mechanisms are provided to select paths based on path diversity.","Title: Leveraging an homomorphic encryption library to implement a coordination service\nYear: 2016\n\nAbstract: The paper presents MorphicLib, a new partial homomorphic cryptography library written in Java that can be used to implement a wide-range of applications. The paper shows the use of the library with the HomomorphicSpace coordination service. This service is a tuple space that stores encrypted tuples but still supports operations like returning tuples with values within a certain range.","Title: Feature set tuning in statistical learning network intrusion detection\nYear: 2016\n\nAbstract: The detection of security-related events using machine learning approaches has been extensively investigated. In particular, machine learning applied to network intrusion detection systems (NIDS) has attracted a lot of attention due to its good generalization and unknown attack detection capabilities. A number of classification techniques have been used for this purpose, revealing good generalization properties. In this paper we go one step further by evaluating the performance of NIDSs when feature set tuning and reduction are realized. We evaluate a number of state of the art learning algorithms that are raising much interest but have not been used for intrusion detection yet. We compare a representative set of algorithms: Ada, ROC-based learners, two types of Classification Trees, Boosted Logistic Regression, Generalized Linear Models, Gradient Boosting Machines, and Neural Networks. The main objective is to reduce the number of features used - thus also the size of the data processed - to improve speed while maintaining adequate accuracy.","Title: State machine replication in containers managed by Kubernetes.\nYear: 2017\n\nAbstract: Computer virtualization brought fast resource provisioning to data centers and the deployment of pay-per-use cost models. The system virtualization provided by containers like Docker has improved this flexibility of resource provisioning. Applications that require more restrictive agreement and ordering guarantees can also benefit from operating inside containers. This paper proposes the integration of coordination services in a container management system called Kubernetes (k8s), seeking to restrict the containers size and to offer automatic state replication. A protocol that uses shared memory available in Kubernetes was developed, and an evaluation was conducted to show the viability of the proposal.","Title: A Systematic Approach for the Application of Restricted Boltzmann Machines in Network Intrusion Detection.\nYear: 2017\n\nAbstract: A few exploratory works studied Restricted Boltzmann Machines (RBMs) as an approach for network intrusion detection, but did it in a rather empirical way. It is possible to go one step further taking advantage from already mature theoretical work in the area. In this paper, we use RBMs for network intrusion detection showing that it is capable of learning complex datasets. We also illustrate an integrated and systematic way of learning. We analyze learning procedures and applications of RBMs and show experimental results for training RBMs on a standard network intrusion detection dataset.","Title: Chrysaor: Fine-Grained, Fault-Tolerant Cloud-of-Clouds MapReduce.\nYear: 2017\n\nAbstract: MapReduce is a framework for processing large data sets much used in the context of cloud computing. MapReduce implementations like Hadoop can tolerate crashes and file corruptions, but not arbitrary faults. Unfortunately, there is evidence that arbitrary faults do occur and can affect the correctness of MapReduce job executions. Furthermore, many outages of major cloud offerings have been reported, raising concerns about the dependence on a single cloud. In this paper we propose a novel execution system that allows to scale out MapReduce computations to a cloud-of-clouds and tolerate arbitrary faults, malicious faults, and cloud outages. Our system, Chrysaor, is based on a fine-grained replication scheme that tolerates faults at the task level. Our solution has three important properties: it tolerates the above-mentioned classes of faults at reasonable cost; it requires minimal modifications to the users' applications; and it does not involve changes to the Hadoop source code. We performed an extensive evaluation of our system in Amazon EC2, showing that our fine-grained solution is efficient in terms of computation by recovering only faulty tasks. This is achieved without incurring a significant penalty for the baseline case (i.e., without faults) in most workloads.","Title: Light-SPD: a platform to prototype secure mobile applications\nYear: 2016\n\nAbstract: Securely storing sensitive personal data is critical for protecting privacy. Currently, many persons use smartphones to store their private data. However, smartphones suffer from many security issues. To overcome this situation, the PCAS project is designing a secure personal storage device called the Secure Portable Device (SPD), to be attached to a smartphone for securely storing sensitive personal data. However, this device is unavailable, closed, and expensive to deploy for prototyping applications. We propose a platform that emulates the SPD and the smartphone using a board with an ARM processor with the TrustZone security extension. This platform is open, inexpensive, and secure. A payment application is used as an example to show the platform's capabilities. As a proof-of-concept, we implemented this platform and provide a performance evaluation using a i.MX53 board.","Title: T2Droid: A TrustZone-Based Dynamic Analyser for Android Applications\nYear: 2017\n\nAbstract: Android has become the most widely used mobile operating system (OS) in recent years. There is much research on methods for detecting malicious Android applications. Dynamic analysis methods detect such applications by evaluating their behaviour during execution. However, such mechanisms may be ineffective as malware is often able to disable antimalware software. This paper presents the design of T2DROID, a dynamic analyser for Android that uses traces of Android API function calls and kernel syscalls, and that is protected from malware by leveraging the ARM TrustZone security extension. In our experimental evaluation T2DROID achieved accuracy and precision of 0.98 and 0.99, respectively, with a kNN classifier.","Title: REPSYS: A Robust and Distributed Reputation System for Delay-Tolerant Networks.\nYear: 2017\n\nAbstract: Distributed reputation systems can be used to foster cooperation between nodes in decentralized and self-managed systems due to the nonexistence of a central entity. In this paper, a Robust and Distributed Reputation System for Delay-Tolerant Networks (REPSYS) is proposed. REPSYS is robust because despite taking into account first- and second-hand information, it is resilient against false accusations and praise, and distributed, as the decision to interact with another node depends entirely on each node. Simulation results show that the system is capable, while evaluating each node's participation in the network, to detect on the fly nodes that do not accept messages from other nodes and that disseminate false information even while colluding with others, and while evaluating how honest is each node in the reputation system, to classify correctly nodes in most cases.","Title: Consistency Of Surface Electromyography Assessment At Lower Limb Selected Muscles During Vertical Countermovement\nYear: 2017\n\nAbstract: Given the difficulty of invasive methods to assess muscle action during natural human movement, surface electromyography (sEMG) has been increasingly used to capture muscle activity in relation to kinesiological analysis of specific tasks. Isolated isometric, concentric and eccentric forms of muscle action have been receiving the most attention for research purposes. Nevertheless natural muscle action frequently involves the use of a preceding eccentric muscle action as a form of potentiation of immediate muscle concentric action, in what is designated as muscle stretch-shortening cycle (SSC). The most frequently applied protocols for the evaluation of SSC on vertical jumps are by virtue of their reproducibility and control of experimental conditions, squat jump (SJ) without countermovement (CM), countermovement jump (CMJ) with long CM and drop jump (DJ) with short CM. The methods used to extract information and relationship of the captured signals also present a high diversity, with the question about the consistency of the methods and obtained results. The objective of this study is to evaluate the consistency of the analysis and results by applying different EMGs signal analysis techniques related to strategic muscle groups of the lower limbs at different countermovement evaluated in vertical jumps. Raw sEMG signals of 5 lower limb muscles of 6 subjects during SJ, CMJ and DJ were rectified, filtered and obtained their envelope, and then correlated (CR) for detection of synergistic, agonist and antagonist activity, applied principal component analysis (PCA) for the detection of uncorrelated components explaining maximum variability and normalized cross-correlation (CCRN) for detection of maximum correlations and time lag. CR of EMG envelopes presented higher coactivities (CoA) in DJ relative to SJ and these CoA superior to CMJ with greater synergy in DJ relative to SJ and CMJ that present several loop cycles corresponding to time lag of activity. CCRN of the EMG envelopes presented also higher CoA in DJ when compared to SJ and both higher CoA to CMJ. PCA allowed to detect a principal component (PC) explaining 92.2% of the variability of EMG in DJ, 90.6% in SJ and 78.7% in CMJ, the second PC responsible for the explanation of 4.9% variability in DJ, 6.7% in SJ and 15.3% in CMJ.","Title: Xor-Overlay Topology Management beyond Kademlia.\nYear: 2017\n\nAbstract: Kademlia is a widely successful Distributed Hash Table (DHT) implementation, better known for its use in the BitTorrent protocol. In this paper, we revisit its overlay management separately from the DHT operations to allow it to be used with other distributed abstractions by providing an accurate and consistent view of the k-closest nodes to any given identifier. We then present invariants that avoid the irregularities that are necessary with the original k-bucket design and improve on later published solutions by not needing an additional parameter to tune. We then provide a specification of a distributed abstraction that provides the automatic management of routing tables using our invariants and a pseudo-code implementation of that abstraction. We finally sketch how our abstraction may be used for a security mechanism and how it could be combined with other known distributed abstractions to provide other services than file sharing in xor-based overlay networks enabling xor-based network overlays to go beyond their original Kademlia design.","Title: Demonstrating a Tool for Injection Attack Prevention in MySQL\nYear: 2017\n\nAbstract: Despite the significant efforts put in building more secure web applications, cases of high impact breaches continue to appear. Vulnerabilities in web applications are often created due to inconsistencies in the way SQL queries are believed to be run and the way they are actually executed by a Database Management System (DBMS). This paper presents a demonstration of SEPTIC, a mechanism that detects and blocks injection attacks inside the DBMS. The demonstration considers a scenario of a non-trivial PHP web application, backed by a MySQL DBMS, which was modified to include SEPTIC. It presents how SEPTIC blocks injection attacks without compromising the application correctness and performance. In addition, SEPTIC is compared to alternative approaches, such as sanitizations carried out with standard functions provided language and a web application firewall.","Title: On the Design of Resilient Multicloud MapReduce.\nYear: 2017\n\nAbstract: Faced with the challenge of dependability, we have recently explored multicloud solutions to increase the resilience and availability of MapReduce. Based on this experience, we present system design guidelines that allow the scaling out of MapReduce computation to multiple clouds to tolerate arbitrary and malicious faults, as well as cloud outages. Crucially, the techniques we introduce have reaso...","Title: On Combining Diverse Static Analysis Tools for Web Security: An Empirical Study\nYear: 2017\n\nAbstract: Developers frequently rely on free static analysis tools to automatically detect vulnerabilities in the source code of their applications, but it is well-known that the performance of such tools is limited and varies from one software development scenario to another, both in terms of coverage and false positives. Diversity is an obvi-ous direction to take to improve coverage, as different tools usual-ly report distinct vulnerabilities, but this may come with an in-crease in the number of false alarms. In this paper, we study the problem of combining diverse static analysis tools to detect web vulnerabilities, considering four software development scenarios with different goals and constraints, ranging from low budget to high-end (e.g., business critical) applications. We conducted an experimental campaign with five free static analysis tools to detect vulnerabilities in a workload composed by 134 WordPress plugins. Results clearly show that the best solution depends on the development scenario. Furthermore, in some cases, a single tool performs better than the best combination of tools.","Title: Rectify: black-box intrusion recovery in PaaS clouds.\nYear: 2017\n\nAbstract: Web applications hosted on the cloud are exposed to cyberattacks and can be compromised by HTTP requests that exploit vulnerabilities. Platform as a Service (PaaS) offerings often provide a backup service that allows restoring application state after a serious attack, but all valid state changes since the last backup are lost. We propose Rectify, a new approach to recover from intrusions on applications running in a PaaS. Rectify is a service designed to be deployed alongside the application in a PaaS container. It does not require modifications to the software and the recovery can be performed by a system administrator. Machine learning techniques are used to associate the requests received by the application to the statements issued to the database. Rectify was evaluated using three widely used web applications - Wordpress, LimeSurvey and MediaWiki - and the results show that the effects of malicious requests can be removed whilst preserving the valid application data.","Title: REPSYS: A Robust and Distributed Incentive Scheme for Collaborative Caching and Dissemination in Content-Centric Cellular-Based Vehicular Delay-Tolerant Networks.\nYear: 2018\n\nAbstract: In this article, a robust and distributed incentive scheme for collaborative caching and dissemination in content-centric cellular-based vehicular delay-tolerant networks (REPSYS) is proposed. REPSYS is robust because despite taking into account first- and second-hand information, it is resilient against false accusations and praise, and distributed, as the decision to interact with another node d...","Title: Introspection for ARM TrustZone with the ITZ Library\nYear: 2018\n\nAbstract: TrustZone is an extension of the ARM architecture that allows software executed in ARM processors to be split in two environments: the normal world that runs a common operating system (e.g., Android or Linux) and its applications, and the secure world that runs security services or others that need to be isolated from the normal world. This work aims to provide support for analyzing the security status of the normal world from the secure world. For this purpose, we present a Virtual Machine Introspection (VMI) library that leverages the TrustZone architecture. VMI tools and the library run in the secure world and inspect the normal world. We present an experimental evaluation of the library in an i.MX53 development board.","Title: FlowHacker: Detecting Unknown Network Attacks in Big Traffic Data Using Network Flows\nYear: 2018\n\nAbstract: Traditional Network Intrusion Detection Systems (NIDSs) inspect the payload of the packets looking for known intrusion signatures or deviations from normal behavior, but inspecting traffic at the current speed of Internet Service Provider (ISP) networks is difficult or even unfeasible. This paper presents an approach to detect malicious traffic and identify malicious hosts by inspecting flows, leveraging a combination of unsupervised machine learning and threat intelligence, without requiring either previous knowledge about attacks or traffic without attacks. The approach was implemented in the FlowHacker NIDS and evaluated with two kinds of traffic flows: synthetic traffic flows and real ISP traffic flows.","Title: Benchmarking Static Analysis Tools for Web Security.\nYear: 2018\n\nAbstract: Static analysis tools are recurrently used by developers to search for vulnerabilities in the source code of web applications. However, distinct tools provide different results depending on factors such as the complexity of the code under analysis and the application scenario; thus, missing some of the vulnerabilities while reporting false problems. Benchmarks can be used to assess and compare dif...","Title: Generalized Lower Limb Joint Angular Phase Space Analysis of Subject Specific Normal and Modified Gait.\nYear: 2018\n\nAbstract: This study presents and applies generalized angular phase space analysis to lower limb joint angles of specific subject during normal and modified gait for discrimination of gait and joint angular movements. Case study of an adult healthy male in-vivo and noninvasive kinematic assessment of skin surface adhesive markers at lower limb was performed at human movement lab during normal gait, stiff knee gait and slow running. Musculoskeletal modeling was performed using AnyGait v.0.92 morphing Twente Lower Extremity Model (TLEM) to match the size and joint morphology of the stick-figure model. Inverse kinematics was performed obtaining hip, knee and ankle joint flexion-extension angular displacements, velocities and accelerations. Generalized phase space analysis was applied to lower limb joint angular displacements, velocities and accelerations. Directional statistics was applied to generalized phase planes with mean direction, resultant length and circular standard deviation assessment. Rayleigh test was employed for directional concentration and coordination assessment, and Watson's $\\mathrm{U^{2$ goodness of fit test applied to the von Mises distribution. Results point for the importance of subject specific study, generalized joint angular phase space analysis, comparing results with other normalization methods and validation of applied methods with qualitative clinical analysis.","Title: RockFS: Cloud-backed File System Resilience to Client-Side Attacks.\nYear: 2018\n\nAbstract: Cloud-backed file systems provide on-demand, high-availability, scalable storage. Their security may be improved with techniques such as erasure codes and secret sharing to fragment files and encryption keys in several clouds. Attacking the server-side of such systems involves penetrating one or more clouds, which can be extremely difficult.\n\nDespite all these benefits, a weak side remains: the client-side. The client devices store user credentials that, if stolen or compromised, may lead to confidentiality, integrity, and availability violations. In this paper we propose RockFS, a cloud-backed file system framework that aims to make the client-side of such systems resilient to attacks. RockFS protects data in the client device and allows undoing unintended file modifications.","Title: Leveraging Arm Trustzone And Verifiable Computing To Provide Auditable Mobile Functions\nYear: 2018\n\nAbstract: The increase of personal data on mobile devices has been followed by legislation that forces service providers to process and maintain users' data under strict data protection policies. In this paper, we propose a new primitive for mobile applications called auditable mobile function (AMF) to help service providers enforcing such policies by enabling them to process sensitive data within users' devices and collecting proofs of function execution integrity. We present SafeChecker, a computation verification system that provides mobile application support for AMFs, and evaluate the practicality of different usage scenario AMFs on TrustZone-enabled hardware.","Title: An empirical study on combining diverse static analysis tools for web security vulnerabilities based on development scenarios\nYear: 2019\n\nAbstract: Automated Static Analysis Tool (ASATs) are one of the best ways to search for vulnerabilities in applications, so they are a resource widely used by developers to improve their applications. However, it is well-known that the performance of such tools is limited, and their detection capabilities may not meet the requirements of the project regarding the criticality of the application. Diversity is an obvious direction to take to improve the true positives, as different tools usually report distinct vulnerabilities, however with the cost of also increasing the false positives, which may be unacceptable in some scenarios. In this paper, we study the problem of combining diverse ASATs to improve the overall detection of vulnerabilities in web applications, considering four development scenarios with different criticality goals and constraints. These scenarios range from low budget to high-end (e.g., business critical) web applications. We tested with five ASATs under two datasets, one with real WordPress plugins and another with synthetic test cases. Our findings revealed that combining the outputs of several ASATs does not always improve the vulnerability detection performance over a single ASAT. By using our procedure a developer is able to choose which is the best combination of ASATs that fits better in the project requirements.","Title: NoSQL Undo: Recovering NoSQL databases by undoing operations\nYear: 2016\n\nAbstract: NoSQL databases offer high throughput, support for huge data structures, and capacity to scale horizontally at the expense of not supporting relational data, ACID consistency and a standard SQL syntax. Due to their simplicity and flexibility, NoSQL databases are becoming very popular among web application developers. However, most NoSQL databases only provide basic backup and restore mechanisms, which allow recovering databases from a crash, but not to remove undesired operations caused by accidental or malicious actions. To solve this problem we propose NOSQL UNDO, a recovery approach and tool that allows database administrators to remove the effect of undesirable actions by undoing operations, leading the system to a consistent state. NOSQL UNDO leverages the logging and snapshot mechanisms built-in NoSQL databases, and is able to undo operations as long as they are present in the logs. This is, as far as we know, the first recovery service that offers these capabilities for NoSQL databases. The experimental results with MongoDB show that it is possible to undo a single operation in a log with 1,000,000 entries in around one second and to undo 10,000 incorrect operations in less than 200 seconds.","Title: ePRIVO: An Enhanced PRIvacy-preserVing Opportunistic Routing Protocol for Vehicular Delay-Tolerant Networks.\nYear: 2018\n\nAbstract: This paper proposes an enhanced PRIvacy preserVing opportunistic routing protocol (ePRIVO) for vehicular delay-tolerant networks (VDTN). ePRIVO models a VDTN as a time-varying neighboring graph where edges correspond to neighboring relationship between pairs of vehicles. It addresses the problem of vehicles taking routing decision meanwhile keeping their information private, i.e., vehicles compute...","Title: Pando: Personal Volunteer Computing in Browsers.\nYear: 2019\n\nAbstract: The large penetration and continued growth in ownership of personal electronic devices represents a freely available and largely untapped source of computing power. To leverage those, we present Pando, a new volunteer computing tool based on a declarative concurrent programming model and implemented using JavaScript, WebRTC, and WebSockets. This tool enables a dynamically varying number of failure-prone personal devices contributed by volunteers to parallelize the application of a function on a stream of values, by using the devices' browsers. We show that Pando can provide throughput improvements compared to a single personal device, on a variety of compute-bound applications including animation rendering and image processing. We also show the flexibility of our approach by deploying Pando on personal devices connected over a local network, on Grid5000, a French-wide computing grid in a virtual private network, and seven PlanetLab nodes distributed in a wide area network over Europe.","Title: SEPTIC: Detecting Injection Attacks and Vulnerabilities Inside the DBMS\nYear: 2019\n\nAbstract: Databases continue to be the most commonly used backend storage in enterprises, but they are often integrated with vulnerable applications, such as web frontends, which allow injection attacks to be performed. The effectiveness of such attacks stems from a semantic mismatch between how SQL queries are believed to be executed and the actual way in which databases process them. This leads to subtle vulnerabilities in the way input validation is done in applications. In this paper, we propose SEPTIC, a mechanism for DBMS attack prevention, which can also assist on the identification of the vulnerabilities in the applications. The mechanism was implemented in MySQL and evaluated experimentally with various applications and alternative protection approaches. Our results show no false negatives and no false positives with SEPTIC, on the contrary to other solutions. They also show that SEPTIC introduces a low performance overhead, in the order of 2.2%.","Title: Genet: A Quickly Scalable Fat-Tree Overlay for Personal Volunteer Computing using WebRTC\nYear: 2019\n\nAbstract: The following topics are dealt with: multi-agent systems; learning (artificial intelligence); decision making; cloud computing; Internet of Things; Bayes methods; configuration management; psychology; interactive systems; software agents.","Title: Secure cloud-of-clouds storage with space-efficient secret sharing\nYear: 2021\n\nAbstract: Cloud storage services are top-rated, but there are often concerns about the security of the files there stored. Clouds-of-clouds or multi-clouds are being explored in order to improve that security. The idea is to store the files in several clouds, ensuring integrity and availability. Confidentiality, however, is obtained by encrypting the files with block ciphers that do not provide provable security. Secret sharing allows distributing files among the clouds providing information-theoretic security/secrecy. However, existing secret sharing schemes are space-inefficient (the size of the shares is much larger than the size of the secret) or purely theoretical. In this paper, we propose the first practical space-efficient secret sharing scheme that provides information-theoretic security, which we denominate PRactical Efficient Secret Sharing (PRESS). Moreover, we present the Secure CloUD storage (SCUD) service, a new cloud-of-clouds storage service that leverages PRESS to provide file confidentiality. Additionally, SCUD provides data integrity and availability, leveraging replication.","Title: Omega: A Secure Event Ordering Service for the Edge\nYear: 2022\n\nAbstract: The edge computing paradigm extends cloud computing with storage and processing capacity close to the edge of the network, which can be materialized by using many fog nodes placed in multiple geographic locations. Fog nodes are likely to be vulnerable to tampering, so it is important to protect the functions they provide from attacks. A key building block of many distributed applications is an ordering service that keeps track of cause-effect dependencies among events and that allows events to be processed in an order that respects causality. This article presents the design and implementation of a secure event ordering service for fog nodes. Our service, named Omega, leverages the availability of a Trusted Execution Environment (TEE), based on SGX technology, to offer fog clients guarantees regarding the order in which events are applied and served, even when fog nodes are compromised. We have also built OmegaKV, a key-value store that uses Omega to offer causal consistency. Experimental results show that the ordering service can be secured without violating the latency constraints of time-sensitive edge applications, despite the overhead associated with using a TEE. Omega introduces an additional latency of approximately 4ms, that contrary to cloud based solutions, allows latency values in the 5ms-30ms range, as required by time-sensitive edge applications.","Title: Enabling Cross-Jurisdiction Digital Asset Transfer\nYear: 2021\n\nAbstract: Enabling blockchain-based digital asset exchanges requires blockchain interoperability capabilities. Although some solutions have been proposed in recent years, asset and crypto-currency transfers across legal jurisdictions are still an unsolved problem. To realize this vision, we propose Hermes, a fault-tolerant middleware that connects blockchain networks, enabling the transfer of data and value...","Title: Fractal Brownian Motion Assessment of the Center of Pressure Excursion During Impulse Phase on Standard Vertical Jump\nYear: 2021\n\nAbstract: This study presents and applies fractal Brownian motion assessment of the center of pressure (COP) excursion during feet ground contact on standard vertical jump impulse phase with long and short countermovement (CM) in relation with lower limb muscle stretch-shortening cycle (SSC) comparing it with no CM and SSC. Fifty-four tests were performed by a group of six healthy male students of sports and physical education degree without previous injury, specific training, or fitness ability. Three repetitions were performed by each subject of a squat jump (SJ) without CM and SSC, countermovement jump (CMJ) with long CM and SSC, as well as drop jump (DJ) with short CM and SSC after depth jump from a 40 cm step. During trial tests ground reaction force and force moments were acquired with force platform and impulse phases were segmented for COP coordinates computation. Fractal Brownian motion analysis of COP excursion during impulse phases conduced to detection of differences between critical time and displacement as well as short and long-term diffusion coefficient (Ds, Dl) and Hurst index scale exponent (Hs, Hl), with Ds, Dl presenting statistical significative correlations -0.491, -0.559 and Hs, Hl non statistical significative correlations 0.266 and -0.424 with MVJ height (ht) at 5% significance for explaining underlying mechanisms on CM and SSC at MVJ. Clinical Relevance- This work contributes with new method for the study expansion of the center of pressure excursion and stability during feet ground contact from orthostatic standing position to the impulse phase during standard maximum vertical jump as the most adequate method for assessment of lower limb muscle stretch-shortening cycle.","Title: Hermes: Fault-tolerant middleware for blockchain interoperability\nYear: 2022\n\nAbstract: Blockchain interoperability reduces the risk of investing in blockchain systems by avoiding vendor lock-in, enabling a new digital economy, and providing migration capabilities. However, seamless interoperability among enterprises requires service providers to comply with different regulations, e.g., data privacy regulations and others that apply to financial services. For supporting interoperability, organizations can connect to each blockchain via a gateway. However, these gateways should be resilient to crashes to maintain a consistent state across ledgers. To realize this vision, we propose Hermes, a fault-tolerant middleware that connects blockchain networks and is based on the Open Digital Asset Protocol (ODAP). Hermes is crash fault-tolerant by allying a new protocol, ODAP-2PC, with a log storage API that can leverage blockchain to secure logs, providing transparency, auditability, availability, and non-repudiation. We briefly explore a use case for cross-jurisdiction asset transfers, illustrating how one can leverage Hermes to support cross-chain transactions compliant with legal and regulatory frameworks.","Title: CyberVTI: Cyber Visualization Tool for Intrusion Detection\nYear: 2021\n\nAbstract: This paper presents the Cyber Visualization Tool for Intrusion detection (CYBERVTI), a tool that provides intrusion detection algorithms with an effective graphical interface. The goals of the tool are twofold. First, it aims to aid the human analyst on observing ongoing threats as a step towards responding to these attacks. Second, it aims to help the analyst study the performance of the algorithms with different parameters, in order to decide which combination best suits his goals. The tool integrates a set of recently-proposed intrusion detection algorithms based on unsupervised machine learning, which it aims to help configuring. Cybervti follows a client-server system architecture and implements a REST API that mediates the communication between the server and the GUI on the client-side. A significant challenge is to define data structures that allow storing and accessing data efficiently in an interactive manner. A clear and minimalist visual aspect was chosen for the GUI, containing functionalities that enable the user to analyze the network data in a simple and clear way. For system evaluation, we used the ISOIIEC 25010:2011 requirements. For validation, we compared the results obtained by our tool with the results described in the original papers that present the algorithms.","Title: SRX-Secure Data Backup and Recovery for SGX Applications\nYear: 2022\n\nAbstract: Intel SGX improves the security of applications by shielding code and data from untrusted software in enclaves. Since enclaves lose their state when closed, that state has to be sealed, i.e., cryptographically protected with a secret key, and stored outside the enclave boundary. In SGX, the used key is bound to both the enclave and the processor that sealed the data, so it is unfeasible for any enclave in another computer to derive the same secret key to unseal such data. This offers security to the data, but also makes it impossible to recover that data if the original computer is damaged or stolen. In order to support backup and recovery of data sealed by enclaves, we propose SRX, a solution for sharing sealed data amongst a restricted set of SGX-enabled computers executing the same enclave code. Enclaves using SRX have access to common keys to seal and unseal enclave data, allowing the sharing of sealed data among the trusted domain. SRX guarantees that these secret keys are never exposed outside the trusted domain. SRX was implemented and evaluated with two applications: a bitcoin wallet and a password manager.","Title: A survey on business process view integration: past, present and future applications to blockchain\nYear: 2022\n\nAbstract: Purpose The complexity of business environments often causes organizations to produce several inconsistent views of the same business process (BP), leading to fragmentation. BP view integration attempts to produce an integrated view from different views of the same model, facilitating the management of BP models. Design/methodology/approach To study the trends of BP view integration, the authors conduct an extensive and systematic literature review to summarize findings since the 1970s. With a starting corpus of 918 documents, this survey draws up a systematic inventory of solutions used in academia and industry. By narrowing it down to 71 articles, the authors discuss in-depth 17 BP integration techniques papers, classifying each solution according to 9 criteria. Findings The authors' study shows that most view-integration methods (11) utilize annotation-based matching, based on formal merging rules. While most solutions are formalized, only approximately half are validated with a real-world use case scenario. View integration can be applied to areas other than database schema integration and BP view integration. Practical implications By summarizing existing knowledge up to June 2021, the authors explore possible future research directions. The authors highlight the application of view integration to the blockchain research area, where stakeholders can have different views on the same blockchain. The authors expect that this study contributes to interdisciplinary research across view integration, namely to the context of blockchain. Originality/value This survey serves to pave the way for future trends, where the authors highlight the application of view integration to blockchain research.","Title: Fingerprinting for Web Applications: From Devices to Related Groups\nYear: 2016\n\nAbstract: Identifying users and user devices is as important in web applications as in many other contexts. In web applications, user identification usually involves an authentication process, e.g., providing a username and a password. Identification is also possible without explicit authentication using cookies or device fingerprints. Device fingerprinting is also useful for other purposes, e.g., to serve as a second factor of authentication. Recently some interest appeared in the problem of cross-device fingerprinting, i.e., of the identification of the same user in different devices using fingerprinting. We target a variation of the problem that we call related group fingerprinting. We define a related group as a set of persons (e.g., a family) that share the same home network. We devised a related group fingerprinting scheme that we evaluated experimentally with data from hundreds of users. This evaluation suggests that group fingerprinting is feasible."],"string":"[\n \"Title: Active quorum systems\\nYear: 2010\\n\\nAbstract: This paper outlines a flexible suite of object replication protocols that brings together Byzantine quorum systems registers and state machine replication. These protocols enable the implementation of Byzantine fault-tolerant applications that make minimal assumptions about the environment and that run in at most two more communication steps in almost all cases of non-favorable executions (in comparison with favorable executions).\",\n \"Title: RITAS: Services for Randomized Intrusion Tolerance\\nYear: 2011\\n\\nAbstract: Randomized agreement protocols have been around for more than two decades. Often assumed to be inefficient due to their high expected communication and computation complexities, they have remained overlooked by the community-at-large as a valid solution for the deployment of fault-tolerant distributed systems. This paper aims to demonstrate that randomization can be a very competitive approach even in hostile environments where arbitrary faults can occur. A stack of randomized intrusion-tolerant protocols is described and its performance evaluated under several settings in both local-area-network (LAN) and wide-area-network environments. The stack provides a set of relevant services ranging from basic communication primitives up to atomic broadcast.The experimental evaluation shows that the protocols are efficient, especially in LAN environments where no performance reduction is observed under certain Byzantine faults.\",\n \"Title: On the Effects of Finite Memory on Intrusion-Tolerant Systems\\nYear: 2007\\n\\nAbstract: Intrusion tolerance has been proposed as a new paradigm for computer systems security [2, 7]. The idea is to apply the fault tolerance paradigm in the domain of systems security, accepting that malicious faults (attacks, intrusions) can never be entirely prevented, and that highly resilient systems have to tolerate these faults.\",\n \"Title: Securing energy metering software with automatic source code correction.\\nYear: 2013\\n\\nAbstract: Industry is using power meters to monitor the consumption of energy and achieving cost savings. This monitoring often involves energy metering software with a web interface. However, web applications often have vulnerabilities that can be exploited by cyber-attacks. We present an approach and a tool to solve this problem by analyzing the application source code and automatically inserting fixes to remove the discovered vulnerabilities. We demonstrate the use of the tool with two open source energy metering applications in which it found and corrected 17 vulnerabilities. By looking in more detail into some of these vulnerabilities, we argue that they are very serious, leading to the following impacts: violation of user privacy, counter the benefits of energy metering, and serve as entering points for attacks on other user software.\",\n \"Title: Evaluating Byzantine Quorum Systems\\nYear: 2007\\n\\nAbstract: Replication is a mechanism extensively used to guaran- tee the availability and good performance of data storage services. Byzantine Quorum Systems (BQS) have been pro- posed as a solution to guarantee the consistency of that kind of services, even if some of the replicas fail arbitrar- ily. Many BQS have been proposed recently, but compar- ing their performance is not simple. In fact, it has been shown that theoretical metrics like the number of steps or communication rounds say as much about the practical per- formance of distributed algorithms as they hide. This pa- per presents a comparative evaluation of several BQS al- gorithms in the literature. The evaluation is based both on experiments and simulations. For that purpose, a framework for evaluating BQS called BQSNeko was developed. The re- sults of the evaluation allow a better understanding of the algorithms and the tradeoffs involved.\",\n \"Title: Efficient Byzantine Fault-Tolerance\\nYear: 2013\\n\\nAbstract: We present two asynchronous Byzantine fault-tolerant state machine replication (BFT) algorithms, which improve previous algorithms in terms of several metrics. First, they require only 2f+1 replicas, instead of the usual 3f+1. Second, the trusted service in which this reduction of replicas is based is quite simple, making a verified implementation straightforward (and even feasible using commercial trusted hardware). Third, in nice executions the two algorithms run in the minimum number of communication steps for nonspeculative and speculative algorithms, respectively, four and three steps. Besides the obvious benefits in terms of cost, resilience and management complexity—fewer replicas to tolerate a certain number of faults—our algorithms are simpler than previous ones, being closer to crash fault-tolerant replication algorithms. The performance evaluation shows that, even with the trusted component access overhead, they can have better throughput than Castro and Liskov's PBFT, and better latency in networks with nonnegligible communication delays.\",\n \"Title: N-party BAR transfer\\nYear: 2011\\n\\nAbstract: We introduce the N-party BAR transfer problem that consists in reliably transferring arbitrarily large data from a set of N producers to a set of N consumers in the BAR model, i.e., in the presence of Byzantine, Altruistic, and Rational participants. The problem considers the existence of a trusted observer that gathers evidence to testify that the producers and consumers have participated in the transfer. We present an algorithm that solves the problem for N≥2f+1, where f is the maximum number of Byzantine processes in each of the producer and consumer sets. We do not impose limits on the number of Rational participants, although they can deviate from the algorithm to improve their utility. We show that our algorithm provides a Nash equilibrium.\",\n \"Title: Byzantine consensus in asynchronous message-passing systems: a survey\\nYear: 2011\\n\\nAbstract: Consensus is a classical distributed systems problem with both theoretical and practical interest. Asynchronous Byzantine consensus is currently at the core of some solutions for the implementation of highly-resilient computing services. This paper surveys Byzantine consensus in message-passing distributed systems, by presenting the main theoretical results in the area, the main classes of algorithms and by discussing important issues like the performance and resilience of these algorithms.\",\n \"Title: The CRUTIAL reference critical information infrastructure architecture: a blueprint\\nYear: 2008\\n\\nAbstract: Critical infrastructures have evolved over the past decades to become largely computerised and interconnected all over the world. This generated the problem of achieving resilience of Critical Information Infrastructures (CII) against computer-borne attacks and severe faults, similar to those observed in the internet. Governments and industry have been pushing an immense research effort in information and systems security, but we believe the complexity of the problem prevents it from being solved using classical security methods. This paper focuses on the computer systems behind electrical utility infrastructures. It proposes the blueprint of a distributed systems architecture that we believe may come to be useful as a reference for modern CII in general. The architecture is instantiatedwithasetofclassesoftechniquesandalgorithms,basedonparadigms providing resilience to faults and attacks in an automatic way.\",\n \"Title: GRIDTS: A New Approach for Fault-Tolerant Scheduling in Grid Computing\\nYear: 2007\\n\\nAbstract: This paper proposes GRIDTS, a grid infrastructure in which the resources select the tasks they execute, on the contrary to traditional infrastructures where schedulers find resources for the tasks. This solution allows scheduling decisions to be made with up-to-date information about the resources, which is difficult in the traditional infrastructures. Moreover, GRIDTS provides fault-tolerant scheduling by combining a set of fault tolerance techniques to cope with crash faults in components of the system. The solution is mainly based a triple space, which supports the scheduling and also provides support for the fault tolerance mechanisms.\",\n \"Title: Byzantine Fault-Tolerant Consensus in Wireless Ad Hoc Networks\\nYear: 2013\\n\\nAbstract: Wireless ad hoc networks, due to their inherent unreliability, pose significant challenges to the task of achieving tight coordination among nodes. The failure of some nodes and momentary breakdown of communications, either of accidental or malicious nature, should not result in the failure of the entire system. This paper presents an asynchronous Byzantine consensus protocol--called Turquois--specifically designed for resource-constrained wireless ad hoc networks. The key to its efficiency is the fact that it tolerates dynamic message omissions, which allows an efficient utilization of the wireless broadcasting medium. The protocol also refrains from computationally expensive public-key cryptographic during its normal operation. The protocol is safe despite the arbitrary failure of $(f\",\n \"Title: Brief announcement: decoupled quorum-based byzantine-resilient coordination in open distributed systems\\nYear: 2006\\n\\nAbstract: The tuple space coordination model, originally introduced in the Linda programming language [2], uses a shared memory object called a tuple space to support coordination that is decoupled both in time – processes do not have to be active at the same time – and space – processes do not need to know each others' addresses. The tuple space can be considered to be a kind of storage that stores tuples, i.e. finite sequences of values. The operations supported are essentially three: inserting a tuple in the space, reading a tuple from the space and removing a tuple from the space.\",\n \"Title: Decoupled Quorum-Based Byzantine-Resilient Coordination in Open Distributed Systems\\nYear: 2007\\n\\nAbstract: Open distributed systems are typically composed by an unknown number of processes running in heterogeneous hosts. Their communication often requires tolerance to temporary disconnections and security against malicious actions. Tuple spaces are a well-known coordination model for this sort of systems. They can support communication that is decoupled both in time and space. There are currently several implementations of distributed fault-tolerant tuple spaces but they are not Byzantine-resilient, i.e., they do not provide a correct service if some replicas are attacked and start to misbehave. This paper presents an efficient implementation of LBTS, a linearizable Byzantine fault-tolerant tuple space. LBTS uses a novel Byzantine quorum systems replication technique in which most operations are implemented by quorum protocols while stronger operations are implemented by more expensive protocols based on consensus. LBTS is linearizable and wait-free, showing interesting performance gains when compared to a similar construction based on state machine replication.\",\n \"Title: Using Attack Injection to Discover New Vulnerabilities\\nYear: 2006\\n\\nAbstract: Due to our increasing reliance on computer systems, security incidents and their causes are important problems that need to be addressed. To contribute to this objective, the paper describes a new tool for the discovery of security vulnerabilities on network connected servers. The AJECT tool uses a speci-cation of the server's communication protocol to automatically generate a large number of attacks accordingly to some prede-ned test classes. Then, while it performs these attacks through the network, it monitors the behavior of the server both from a client perspective and inside the target machine. The observation of an incorrect behavior indicates a successful attack and the potential existence of a vulnerability. To demonstrate the usefulness of this approach, a considerable number of experiments were carried out with several IMAP servers. The results show that AJECT can discover several kinds of vulnerabilities, including a previously unknown vulnerability.\",\n \"Title: The Design of a COTSReal-Time Distributed Security Kernel\\nYear: 2002\\n\\nAbstract: This paper describes the design of a security kernel called TTCB, which has innovative features. Firstly, it is a distributed sub-system with its own secure network. Secondly, the TTCB is real-time, that is, a synchronous subsystem capable of timely behavior. These two characteristics together are uncommon in security kernels. Thirdly, the TTCB can be implemented using only COTS components. We discuss essentially three things in this paper: (1) The TTCB is a simple component providing a small set of basic secure services. It aims at building a new style of protocols to achieve intrusion tolerance, which for the most part execute in insecure, arbitrary failure environments, and resort to the TTCB only in crucial parts of their operation. (2) Besides, the TTCB is a synchronous device supplying functions that may be an enabler of a new generation of timed secure protocols, until now known to be fragile due to attacks on timing assumptions. (3) Finally, we present a design methodology that establishes our hybrid failure assumptions in a well-founded manner. It helps us to achieve a robust design, despite using exclusively COTS components, with the advantage of allowing the security kernel to be easily deployed on widely used platforms.\",\n \"Title: Resilient Intrusion Tolerance through Proactive and Reactive Recovery\\nYear: 2007\\n\\nAbstract: Previous works have studied how to use proactive recovery to build intrusion-tolerant replicated systems that are resilient to any number of faults, as long as recoveries are faster than an upper-bound on fault production assumed at system deployment time. In this paper, we propose a complementary approach that combines proactive recovery with services that allow correct replicas to react and recover replicas that they detect or suspect to be compromised. One key feature of our proactive-reactive recovery approach is that, despite recoveries, it guarantees the availability of the minimum amount of system replicas necessary to sustain system's correct operation. We design a proactive-reactive recovery service based on a hybrid distributed system model and show, as a case study, how this service can effectively be used to augment the resilience of an intrusion-tolerant firewall adequate for the protection of critical infrastructures.\",\n \"Title: An Efficient Byzantine-Resilient Tuple Space\\nYear: 2009\\n\\nAbstract: Open distributed systems are typically composed by an unknown number of processes running in heterogeneous hosts. Their communication often requires tolerance to temporary disconnections and security against malicious actions. Tuple spaces are a well-known coordination model for this kind of systems. They can support communication that is decoupled both in time and space. There are currently several implementations of distributed fault-tolerant tuple spaces but they are not Byzantine-resilient, i.e., they do not provide a correct service if some replicas are attacked and start to misbehave. This paper presents an efficient implementation of a Linearizable Byzantine fault-tolerant Tuple Space (LBTS) that uses a novel Byzantine quorum systems replication technique in which most operations are implemented by quorum protocols while stronger operations are implemented by more expensive protocols based on consensus. LBTS is linearizable and wait-free, showing interesting performance gains when compared to a similar construction based on state machine replication.\",\n \"Title: Automatic detection and correction of web application vulnerabilities using data mining to predict false positives\\nYear: 2014\\n\\nAbstract: Web application security is an important problem in today's internet. A major cause of this status is that many programmers do not have adequate knowledge about secure coding, so they leave applications with vulnerabilities. An approach to solve this problem is to use source code static analysis to find these bugs, but these tools are known to report many false positives that make hard the task of correcting the application. This paper explores the use of a hybrid of methods to detect vulnerabilities with less false positives. After an initial step that uses taint analysis to flag candidate vulnerabilities, our approach uses data mining to predict the existence of false positives. This approach reaches a trade-off between two apparently opposite approaches: humans coding the knowledge about vulnerabilities (for taint analysis) versus automatically obtaining that knowledge (with machine learning, for data mining). Given this more precise form of detection, we do automatic code correction by inserting fixes in the source code. The approach was implemented in the WAP tool and an experimental evaluation was performed with a large set of open source PHP applications.\",\n \"Title: Practical hardening of crash-tolerant systems\\nYear: 2012\\n\\nAbstract: Recent failures of production systems have highlighted the importance of tolerating faults beyond crashes. The industry has so far addressed this problem by hardening crash-tolerant systems with ad hoc error detection checks, potentially overlooking critical fault scenarios. We propose a generic and principled hardening technique for Arbitrary State Corruption (ASC) faults, which specifically model the effects of realistic data corruptions on distributed processes. Hardening does not require the use of trusted components or the replication of the process over multiple physical servers. We implemented a wrapper library to transparently harden distributed processes. To exercise our library and evaluate our technique, we obtained ASC-tolerant versions of Paxos, of a subset of the ZooKeeper API, and of an eventually consistent storage by implementing crash-tolerant protocols and automatically hardening them using our library. Our evaluation shows that the throughput of our ASC-hardened state machine replication outperforms its Byzantine-tolerant counterpart by up to 70%.\",\n \"Title: Worm-IT - A wormhole-based intrusion-tolerant group communication system\\nYear: 2007\\n\\nAbstract: This paper presents Worm-IT, a new intrusion-tolerant group communication system with a membership service and a view-synchronous atomic multicast primitive. The system is intrusion-tolerant in the sense that it behaves correctly even if some nodes are corrupted and become malicious. It is based on a novel approach that enhances the environment with a special secure distributed component used by the protocols to execute securely a few crucial operations. Using this approach, we manage to bring together two important features: Worm-IT tolerates the maximum number of malicious members possible; it does not have to detect the failure of primary-members, a problem in previous intrusion-tolerant group communication systems.\",\n \"Title: Spin One's Wheels? Byzantine Fault Tolerance with a Spinning Primary\\nYear: 2009\\n\\nAbstract: Most Byzantine fault-tolerant state machine replication(BFT) algorithms have a primary replica that is in charge of ordering the clients requests. Recently it was shown that this dependence allows a faulty primary to degrade the performance of the system to a small fraction of what the environment allows. In this paper we present Spinning, a novel BFT algorithm that mitigates such performance attacks by changing the primary after every batch of pending requests is accepted for execution. This novel mode of operation deals with those attacks at a much lower cost than previous solutions, maintaining a throughput equal or better to the algorithm that is usually consider to be the baseline in the area, Castro and Liskov’s PBFT.\",\n \"Title: Asynchronous Byzantine consensus with 2f+1 processes\\nYear: 2010\\n\\nAbstract: Byzantine consensus in asynchronous message-passing systems has been shown to require at least 3f + 1 processes to be solvable in several system models (e.g., with failure detectors, partial synchrony or randomization). Recently a couple of solutions to implement Byzantine fault-tolerant state-machine replication using only 2f + 1 replicas have appeared. This reduction from 3f + 1 to 2f + 1 is possible with a hybrid system model, i.e., by extending the system model with trusted/trustworthy components that constrain the power of faulty processes to have certain behaviors. Despite these important results, the problem of solving Byzantine consensus with only 2f + 1 processes is still far from being well understood. In this paper we present a methodology to transform crash consensus algorithms into Byzantine consensus algorithms with different characteristics, with the assistance of a reliable broadcast primitive that requires trusted/trustworthy components to be implemented. We exemplify the methodology with two algorithms, one that uses failure detectors and one that is randomized. We also define a new flavor of consensus and use it to solve atomic broadcast, showing the practical interest of the transformations.\",\n \"Title: DepSpace: a byzantine fault-tolerant coordination service\\nYear: 2008\\n\\nAbstract: The tuple space coordination model is one of the most interesting coordination models for open distributed systems due to its space and time decoupling and its synchronization power. Several works have tried to improve the dependability of tuple spaces through the use of replication for fault tolerance and access control for security. However, many practical applications in the Internet require both fault tolerance and security. This paper describes the design and implementation of DepSpace, a Byzantine fault-tolerant coordination service that provides a tuple space abstraction. The service offered by DepSpace is secure, reliable and available as long as less than a third of service replicas are faulty. Moreover, the content-addressable confidentiality scheme developed for DepSpace bridges the gap between Byzantine fault-tolerant replication and confidentiality of replicated data and can be used in other systems that store critical data.\",\n \"Title: 4th workshop on recent advances in intrusion-tolerant systems, WRAITS 2010\\nYear: 2010\\n\\nAbstract: Design and operational vulnerabilities are accepted as inevitable in today's complex computer systems. The distributed and networked nature of the systems that are currently in use and being developed facilitate discovery and exploitation of these flaws in increasingly new and easier ways. Intrusion Tolerance acknowledges that it is impossible to completely prevent attacks and intrusions, and that it is often impossible to accurately detect the act of intrusion and stop it early enough. Intrusion Tolerance research therefore aims to develop technologies that enable computer systems to continue to operate correctly despite attacks, and deny the attacker/intruder the success they seek. For instance, an intrusion-tolerant system may suffer partial loss of service or resources due to the attack, but it will continue to provide critical services in a degraded mode or trigger automatic mechanisms to regain and recover the compromised services and resources. Similar goals are being pursued in Survivability, Byzantine Fault Tolerance, Self-regenerative and Autonomic Systems.\",\n \"Title: MITRA: byzantine fault-tolerant middleware for transaction processing on replicated databases\\nYear: 2014\\n\\nAbstract: Replication is often considered a cost-effective solution for building dependable systems with off-the-shelf hardware. Replication software is usually designed to tolerate crash faults, but Byzantine (or arbitrary) faults such as software bugs are well-known to affect transactional database management systems (DBMSs) as many other classes of software. Despite the maturity of replication technology, Byzantine fault-tolerant replication of databases remains a challenging problem. The paper presents MITRA, a middleware for replicating DBMSs and making them tolerant to Byzantine faults. MITRA is designed to offer transparent replication of off-theshelf DBMSs with replicas from different vendors.\",\n \"Title: Finite Memory: A Vulnerability of Intrusion-Tolerant Systems\\nYear: 2008\\n\\nAbstract: In environments like the Internet, faults follow unusual patterns, dictated by the combination of malicious attacks with accidental faults such as long communication delays caused by temporary network partitions. In this scenario, attackers can force buffer overflows in order to leave the system in an inconsistent state or to prevent it from doing progress, causing a denial of service. This paper is about the effects that finite memory has on intrusion-tolerant protocols and systems. We present the problem and propose a generic mitigation technique based on repair nodes that reduces the buffer space requirements. An experimental evaluation of the buffer usage with and without this technique is presented, allowing to assess in practice the effects of finite memory in a real, albeit simple, intrusion-tolerant system.\",\n \"Title: An Infrastructure for Adaptive Fault Tolerance on FT-CORBA\\nYear: 2006\\n\\nAbstract: The fault tolerance provided by FT-CORBA is basically static, that is, once the fault tolerance properties of a group of replicated processes are defined, they cannot be modified in runtime. A support for dynamic reconfiguration of the replication would be highly advantageous since it would allow the implementation of mechanisms for adaptive fault tolerance, enabling FT-CORBA to adapt to the changes that can occur in the execution environment. In this paper, we propose a set of extensions to the FT-CORBA infrastructure in the form of interfaces and object service implementations, enabling it to support dynamic reconfiguration of the replication.\",\n \"Title: Intrusion Tolerance in Wireless Environments: An Experimental Evaluation\\nYear: 2007\\n\\nAbstract: This paper presents a study on the performance of intrusion-tolerant protocols in wireless LANs. The protocols are evaluated in several different environmental settings, and also within the context of a car platooning application for distributed cruise control. The experimental evaluation reveals how performance is affected by the various environmental parameters such as the wireless standard, group size, and network topology. The distributed cruise control application demonstrates the practicability of such protocols, even when subjected to malicious faults.\",\n \"Title: The CRUTIAL Architecture for Critical Information Infrastructures\\nYear: 2007\\n\\nAbstract: In this chapter we discuss the susceptibility of critical information infrastructures to computer-borne attacks and faults, mainly due to their largely computerized nature, and to the pervasive interconnection of systems all over the world. We discuss how to overcome these problems and achieve resilience of critical information infrastructures, through adequate architectural constructs. The architecture we propose is generic and may come to be useful as a reference for modern critical information infrastructures. We discuss four main aspects: trusted components which induce prevention; middleware devices that achieve runtime automatic tolerance and protection; trustworthiness monitoring mechanisms detecting and adapting to non-predicted situations; organization-level security policies and access control models capable of securing global information flows.\",\n \"Title: Intrusion Tolerant Services Through Virtualization: A Shared Memory Approach\\nYear: 2010\\n\\nAbstract: Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distributed applications has been made in recent years. These solutions are designed to make the applications resistant to successful attacks against the system, thereby making services tolerant to intrusions. Recently, some of these studies have considered the use of virtual machines for building a trusted computing environment. This paper presents SMIT (Shared Memory based Intrusion Tolerance), an architecture for Intrusion Tolerance using virtual machines that benefits from a shared memory to simplify the consensus protocol.\",\n \"Title: Randomized Intrusion-Tolerant Asynchronous Services\\nYear: 2006\\n\\nAbstract: Randomized agreement protocols have been around for more than two decades. Often assumed to be inefficient due to their high expected communication and time complexities, they have remained largely overlooked by the community-at-large as a valid solution for the deployment of fault-tolerant distributed systems. This paper aims to demonstrate that randomization can be a very competitive approach even in hostile environments where arbitrary faults can occur. A stack of randomized intrusion-tolerant protocols is described and its performance evaluated under different faultloads. The stack provides a set of relevant services ranging from basic communication primitives up to atomic broadcast. The experimental evaluation shows that the protocols are efficient and no performance reduction is observed under certain Byzantine faults.\",\n \"Title: EBAWA: Efficient Byzantine Agreement for Wide-Area Networks\\nYear: 2010\\n\\nAbstract: The popularity of wide-area computer services has generated a compelling need for efficient algorithms that provide high reliability. Byzantine fault-tolerant (BFT) algorithms can be used with this purpose because they allow replicated systems to continue to provide a correct service even when some of their replicas fail arbitrarily, either accidentally or due to malicious faults. Current BFT algorithms perform well on LANs but when the replicas are distributed geographically their performance is affected by the lower bandwidth and the higher and more heterogeneous network latencies. This paper proposes and evaluates a novel BFT algorithm for WANs that requires fewer communication steps, fewer replicas and has better throughput and latency than others in the literature. The paper presents an extensive evaluation of the algorithm’s performance in several settings and conditions: in a LAN, in real and emulated WANs, with clients close to servers and dispersed geographically, with similar and different communication latencies between clients and servers.\",\n \"Title: From Consensus to Atomic Broadcast: Time-Free Byzantine-Resistant Protocols without Signatures\\nYear: 2006\\n\\nAbstract: This paper proposes a stack of three Byzantine-resistant protocols aimed to be used in practical distributed systems: multi-valued consensus, vector consensus and atomic broadcast. These protocols are designed as successive transformations from one to another. The first protocol, multi-valued consensus, is implemented on top of a randomized binary consensus and a reliable broadcast protocol. The protocols share a set of important structural properties. First, they do not use digital signatures constructed with public-key cryptography, a well-known performance bottleneck in this kind of protocols. Second, they are time-free, i.e. they make no synchrony assumptions, since these assumptions are often vulnerable to subtle but effective attacks. Third, they are completely decentralized, thus avoiding the cost of detecting corrupt leaders. Fourth, they have optimal resilience, i.e. they tolerate the failure of f = ⌊(n-1)/3⌋ out of a total of n processes. In terms of time complexity, the multi-valued consensus protocol terminates in a constant expected number of rounds, while the vector consensus and atomic broadcast protocols have O(f) complexity. The paper also proves the equivalence between multi-valued consensus and atomic broadcast in the Byzantine failure model without signatures. A similar proof is given for the equivalence between multi-valued consensus and vector consensus. These two results have theoretical relevance since they show once more that consensus is a fundamental problem in distributed systems.\",\n \"Title: Low complexity Byzantine-resilient consensus\\nYear: 2005\\n\\nAbstract: The application of the tolerance paradigm to security - intrusion tolerance - has been raising a reasonable amount of attention in the dependability and security communities. In this paper we present a novel approach to intrusion tolerence. The idea is to use privileged components - generically designated by wormholes - to support the execution of intrusion-tolerant protocols, often called Byzantine-resilient in the literature.The paper introduces the design of wormhole-aware intrusion-tolerant protocols using a classical distributed systems problem: consensus. The system where the consensus protocol runs is mostly asynchronous and can fail in an arbitrary way, except for the wormhole, which is secure and synchronous. Using the wormhole to execute a few critical steps, the protocol manages to have a low time complexity: in the best case, it runs in two rounds, even if some processes are malicious. The protocol also shows how often theoretical partial synchrony assumptions can be substantiated in practical distributed systems. The paper shows the significance of the TTCB as an engineering paradigm, since the protocol manages to be simple when compared with other protocols in the literature.\",\n \"Title: Highly Available Intrusion-Tolerant Services with Proactive-Reactive Recovery\\nYear: 2010\\n\\nAbstract: In the past, some research has been done on how to use proactive recovery to build intrusion-tolerant replicated systems that are resilient to any number of faults, as long as recoveries are faster than an upper bound on fault production assumed at system deployment time. In this paper, we propose a complementary approach that enhances proactive recovery with additional reactive mechanisms giving correct replicas the capability of recovering other replicas that are detected or suspected of being compromised. One key feature of our proactive-reactive recovery approach is that, despite recoveries, it guarantees the availability of a minimum number of system replicas necessary to sustain correct operation of the system. We design a proactive-reactive recovery service based on a hybrid distributed system model and show, as a case study, how this service can effectively be used to increase the resilience of an intrusion-tolerant firewall adequate for the protection of critical infrastructures.\",\n \"Title: Byzantine Fault-Tolerant MapReduce: Faults are Not Just Crashes\\nYear: 2011\\n\\nAbstract: MapReduce is often used to run critical jobs such as scientific data analysis. However, evidence in the literature shows that arbitrary faults do occur and can probably corrupt the results of MapReduce jobs. MapReduce runtimes like Hadoop tolerate crash faults, but not arbitrary or Byzantine faults. We present a MapReduce algorithm and prototype that tolerate these faults. An experimental evaluation shows that the execution of a job with our algorithms uses twice the resources of the original Hadoop, instead of the 3 or 4 times more that would be achieved with the direct application of common Byzantine fault-tolerance paradigms. We believe this cost is acceptable for critical applications that require that level of fault tolerance.\",\n \"Title: Randomization can be a healer: consensus with dynamic omission failures\\nYear: 2011\\n\\nAbstract: Wireless ad-hoc networks are being increasingly used in diverse contexts, ranging from casual meetings to disaster recovery operations. A promising approach is to model these networks as distributed systems prone to dynamic communication failures. This captures transitory disconnections in communication due to phenomena like interference and collisions, and permits an efficient use of the wireless broadcasting medium. This model, however, is bound by the impossibility result of Santoro and Widmayer, which states that, even with strong synchrony assumptions, there is no deterministic solution to any non-trivial form of agreement if n - 1 or more messages can be lost per communication round in a system with n processes. In this paper we propose a novel way to circumvent this impossibility result by employing randomization. We present a consensus protocol that ensures safety in the presence of an unrestricted number of omission faults, and guarantees progress in rounds where such faults are bounded by f ≤ ⌈n/2⌉(n-k)+k - 2, where k is the number of processes required to decide, eventually assuring termination with probability 1.\",\n \"Title: Clouds-of-Clouds for Dependability and Security: Geo-replication Meets the Cloud.\\nYear: 2013\\n\\nAbstract: The complexity of large cloud offerings makes it extremely hard to guarantee their dependability and security. This paper extracts lessons from some years of research on the notion of using several clouds instead of a single one-with the objective of achieving high dependability and security. We show that using such clouds-of-clouds it is possible for services to continue to operate correctly despite dependability and security issues in a subset of the clouds. We show this approach with three cases: clouds-of-clouds for storage with the DepSky system; cloud-of- clouds for data processing with Map Reduce; the execution of arbitrary services in clouds-of-clouds with the EBAWA algorithm.\",\n \"Title: CRUTIAL: the blueprint of a reference critical information infrastructure architecture\\nYear: 2006\\n\\nAbstract: In the past few decades, critical infrastructures have become largely computerised and interconnected all over the world. This generated the problem of achieving resilience of critical information infrastructures against computer-borne attacks and severe faults. Governments and industry have been pushing an immense research effort in information and systems security, but we believe the complexity of the problem prevents it from being solved using classical security methods. The paper focuses on the computer systems behind electrical utility infrastructures. It proposes the blueprint of a distributed systems architecture that we believe may come to be useful as a reference for modern critical information infrastructures in general. The architecture is instantiated with a set of classes of techniques and algorithms, based on paradigms providing resilience to faults and attacks in an automatic way.\",\n \"Title: Exploiting Tuple Spaces to Provide Fault-Tolerant Scheduling on Computational Grids\\nYear: 2007\\n\\nAbstract: In this paper we present our vision of establishing self-coordination as the dominant paradigm of operation of future embedded computing environments. This vision is looked at from three different points of view. First of all techniques to model self-coordinating ...\",\n \"Title: Lucy in the sky without diamonds: Stealing confidential data in the cloud\\nYear: 2011\\n\\nAbstract: Cloud Computing is a recent paradigm that is creating high expectations about benefits such as the pay-per-use model and elasticity of resources. However, with this optimism come also concerns about security. In a public cloud, the user's data storage and processing is no longer done inside its premises, but in data centers owned and administrated by the cloud provider. This may be a concern for organizations that deal with critical data, such as medical records. We show that a malicious insider can steal confidential data of the cloud user, so the user is mostly left with trusting the cloud provider. The paper achieves this goal by showing a set of attacks that demonstrate how a malicious insider can easily obtain passwords, cryptographic keys, files and other confidential data. Additionally, the paper shows that recent research results that might be useful to protect data in the cloud, are still not enough to deal with the problem. The paper is a call to arms for research in the topic.\",\n \"Title: On Byzantine generals with alternative plans\\nYear: 2008\\n\\nAbstract: This paper proposes a variation of the Byzantine generals problem (or Byzantine consensus). Each general has a set of good plans and a set of bad plans. The problem is to make all loyal generals agree on a good plan proposed by a loyal general, and never on a bad plan.\",\n \"Title: Byzantine Fault-Tolerant Transaction Processing for Replicated Databases\\nYear: 2011\\n\\nAbstract: Transaction commit is a problem much investigated, both in the databases and systems communities, from the theoretical and practical sides. We present a modular approach to solve this problem in the context of database replication on environments that are subject to Byzantine faults. Our protocol builds on a total order multicast abstraction and is proven to satisfy a set of safety and liveness properties. On the contrary of previous solutions in the literature, it assures strong consistency for transactions, tolerates Byzantine clients and does not need centralized control or multi-version databases. We present an evaluation of a prototype of the system.\",\n \"Title: On the efficiency of durable state machine replication\\nYear: 2013\\n\\nAbstract: State Machine Replication (SMR) is a fundamental technique for ensuring the dependability of critical services in modern internet-scale infrastructures. SMR alone does not protect from full crashes, and thus in practice it is employed together with secondary storage to ensure the durability of the data managed by these services. In this work we show that the classical durability enforcing mechanisms - logging, checkpointing, state transfer - can have a high impact on the performance of SMR-based services even if SSDs are used instead of disks. To alleviate this impact, we propose three techniques that can be used in a transparent manner, i.e., without modifying the SMR programming model or requiring extra resources: parallel logging, sequential checkpointing, and collaborative state transfer. We show the benefits of these techniques experimentally by implementing them in an open-source replication library, and evaluating them in the context of a consistent key-value store and a coordination service.\",\n \"Title: The Crutial Way of Critical Infrastructure Protection\\nYear: 2008\\n\\nAbstract: Critical infrastructures such as the power grid are essentially physical processes controlled by computers connected by networks. They're usually as vulnerable as any other interconnected computer system, but their failure has a high socioeconomic impact. The Critical Utility Infrastructural Resilience (Crutial) project designed an information switch (CIS) to protect these infrastructures. These devices help ensure that incoming and outgoing traffic satisfies the security policy of an infrastructure in face of cyberattacks. A CIS isn't a firewall, but a distributed protection device based on a sophisticated access control model. Furthermore, a CIS is intrusion-tolerant and self-healing, seeking perpetual unattended correct operation.\",\n \"Title: Sharing Memory between Byzantine Processes using Policy-Enforced Tuple Spaces\\nYear: 2006\\n\\nAbstract: The Java messaging service (JMS) is a means to organize communication among distributed applications according to the publish/subscribe principle. If the subscribers install filter rules on the JMS server, JMS can be used as a message routing platform, ...\",\n \"Title: A multi-objective routing algorithm for Wireless Multimedia Sensor Networks\\nYear: 2015\\n\\nAbstract: Graphical abstractDisplay Omitted HighlightsA new multi-objective approach for the routing problem in Wireless Multimedia Sensor Networks (WMSNs) is proposed.Classical approximations optimize a single objective or Quality of Service (QoS) parameter.Classical approximations do not take into account the conflicting nature of QoS parameters which leads to sub-optimal solutions.The proposed approach takes into account multiple QoS requirements such as delay and the Expected Transmission Count (ETX).The case studies applying the proposed approach shows clear improvements on the QoS routing solutions. In this paper, a new multi-objective approach for the routing problem in Wireless Multimedia Sensor Networks (WMSNs) is proposed. It takes into account Quality of Service (QoS) requirements such as delay and the Expected Transmission Count (ETX). Classical approximations optimize a single objective or QoS parameter, not taking into account the conflicting nature of these parameters which leads to sub-optimal solutions. The case studies applying the proposed approach show clear improvements on the QoS routing solutions. For example, in terms of delay, the approximate mean improvement ratios obtained for scenarios 1 and 2 were of 15 and 28 times, respectively.\",\n \"Title: Efficient Byzantine-resilient reliable multicast on a hybrid failure model\\nYear: 2002\\n\\nAbstract: The paper presents a new reliable multicast protocol that tolerates arbitrary faults, including Byzantine faults. This protocol is developed using a novel way of designing secureprotocols which is based on a well-founded hybrid failure model. Despite our claim of arbitrary failure resilience, the protocol needs not necessarily incur the cost of \\\"Byzantine agreement\\\", in number of participants and round/message complexity. It can rely on the existence of a simple distributed security kernel 驴 the TTCB 驴 where the participants only execute crucial parts of the protocol operation, under the protection of a crash failure model. Otherwise, participants follow an arbitrary failure model.The TTCB provides only a few basic services, which allow our protocol to have an efficiency similar to that of accidental fault-tolerant protocols: for f faults, our protocol requires f+2 processes, instead of 3f+1 in Byzantine systems. Besides, the TTCB (which is synchronous) allows secure operation of timed protocols, despite the unpredictable time behavior of the environment (possibly due to attacks on timing assumptions).\",\n \"Title: How to tolerate half less one Byzantine nodes in practical distributed systems\\nYear: 2004\\n\\nAbstract: The application of dependability concepts and techniques to the design of secure distributed systems is raising a considerable amount of interest in both communities under the designation of intrusion tolerance. However, practical intrusion-tolerant replicated systems based on the state machine approach (SMA) can handle at most f Byzantine components out of a total of n = 3f + 1, which is the maximum resilience in asynchronous systems. This paper extends the normal asynchronous system with a special distributed oracle called TTCB. Using this extended system we manage to implement an intrusion-tolerant service based on the SMA with only 2f + 1 replicas. Albeit a few other papers in the literature present intrusion-tolerant services with this approach, this is the first time the number of replicas is reduced from 3f + 1 to 2f + 1. Another interesting characteristic of the described service is a low time complexity.\",\n \"Title: Solving vector consensus with a wormhole\\nYear: 2005\\n\\nAbstract: This paper presents a solution to the vector consensus problem for Byzantine asynchronous systems augmented with wormholes. Wormholes prefigure a hybrid distributed system model, embodying the notion of an enhanced part of the system with \\\"good驴 properties otherwise not guaranteed by the \\\"normal驴 weak environment. A protocol built for this type of system runs in the asynchronous part, where f out of n \\\\geq 3f+1 processes might be corrupted by malicious adversaries. However, sporadically, processes can rely on the services provided by the wormhole for the correct execution of simple operations. One of the nice features of this setting is that it is possible to keep the protocol completely time-free and, in addition, to circumvent the FLP impossibility result by hiding all time-related assumptions in the wormhole. Furthermore, from a performance perspective, it leads to the design of a protocol with a good time complexity.\",\n \"Title: Experimental Comparison of Local and Shared Coin Randomized Consensus Protocols\\nYear: 2006\\n\\nAbstract: The paper presents a comparative performance study of the two main classes of randomized binary consensus protocols: a local coin protocol, with an expected high communication complexity and cheap symmetric cryptography, and a shared coin protocol, with an expected low communication complexity and expensive asymmetric cryptography. The experimental evaluation was conducted on a LAN environment, by varying several system parameters, such as the fault types and number of processes. The analysis shows that there is a significant gap between the theoretical and the practical performance results of these protocols, and provides an important insight into what actually happens during their execution.\",\n \"Title: Sharing Memory between Byzantine Processes Using Policy-Enforced Tuple Spaces\\nYear: 2009\\n\\nAbstract: Despite the large amount of Byzantine fault-tolerant algorithms for message-passing systems designed through the years, only recently algorithms for the coordination of processes subject to Byzantine failures using shared memory have appeared. This paper presents a new computing model in which shared memory objects are protected by fine-grained access policies, and a new shared memory object, the policy-enforced augmented tuple space (PEATS). We show the benefits of this model by providing simple and efficient consensus algorithms. These algorithms are much simpler and requires less shared memory operations, using also less memory bits than previous algorithms based on access control lists ACLs and sticky bits. We also prove that PEATS objects are universal, i.e., that they can be used to implement any other shared memory object, and present lock-free and wait-free universal constructions.\",\n \"Title: 3rd Workshop on Recent Advances on Intrusion-Tolerant Systems WRAITS 2009\\nYear: 2009\\n\\nAbstract: The 3rd Workshop on Recent Advances in Intrusion- Tolerant Systems, held in conjunction with DSN 2009, aims to provide the researchers and practitioners an intimate venue to discuss and collaborate on ground-breaking new ideas and fresh results.\",\n \"Title: Monitoring of bedridden patients: Development of a fall detection tool\\nYear: 2013\\n\\nAbstract: Falls of patients are an important issue in hospitals, it causes severe injuries to the patients, increases hospitalization time and treatment costs. The detection of a fall, in time, provides faster rescue to the patient, preventing more serious injuries, as well as saving nursing time. The MovinSense® is an electronic device designed for monitoring patients to prevent pressure sores, and the main goal of this work was to develop a new tool for this device, with the purpose of detecting if the patient has fallen from the hospital bed, without changing any of the device original features. Experiments for gathering data samples of inertial signals of falling from the bed were obtained using the device. For fall detection a sensitivity of 72% and specificity of 100% were reached. Another algorithm was developed to detect if the patient got out of his/her bed.\",\n \"Title: Monitoring of bedridden patients: Development of a fall detection tool\\nYear: 2013\\n\\nAbstract: Falls of patients are an important issue in hospitals, it causes severe injuries to the patients, increases hospitalization time and treatment costs. The detection of a fall, in time, provides faster rescue to the patient, preventing more serious injuries, as well as saving nursing time. The MovinSense® is an electronic device designed for monitoring patients to prevent pressure sores, and the main goal of this work was to develop a new tool for this device, with the purpose of detecting if the patient has fallen from the hospital bed, without changing any of the device original features. Experiments for gathering data samples of inertial signals of falling from the bed were obtained using the device. For fall detection a sensitivity of 72% and specificity of 100% were reached. Another algorithm was developed to detect if the patient got out of his/her bed.\",\n \"Title: Monitoring of bedridden patients: Development of a fall detection tool\\nYear: 2013\\n\\nAbstract: Falls of patients are an important issue in hospitals, it causes severe injuries to the patients, increases hospitalization time and treatment costs. The detection of a fall, in time, provides faster rescue to the patient, preventing more serious injuries, as well as saving nursing time. The MovinSense® is an electronic device designed for monitoring patients to prevent pressure sores, and the main goal of this work was to develop a new tool for this device, with the purpose of detecting if the patient has fallen from the hospital bed, without changing any of the device original features. Experiments for gathering data samples of inertial signals of falling from the bed were obtained using the device. For fall detection a sensitivity of 72% and specificity of 100% were reached. Another algorithm was developed to detect if the patient got out of his/her bed.\",\n \"Title: Byzantine fault-tolerant state machine replication with twin virtual machines\\nYear: 2013\\n\\nAbstract: The reliability and availability of distributed services can be ensured using replication. We present an architecture and an algorithm for Byzantine fault-tolerant state machine replication. We explore the benefits of virtualization to reliably detect and tolerate faulty replicas, allowing the transformation of Byzantine faults into omission faults. Our approach reduces the total number of physical replicas from 3f+1 to 2f+1. It is based on the concept of twin virtual machines, which involves having two virtual machines in each physical host, each one acting as failure detector of the other.\",\n \"Title: The Final Frontier: Confidentiality and Privacy in the Cloud\\nYear: 2011\\n\\nAbstract: The boundary between the trusted inside and the untrusted outside blurs when a company adopts cloud computing. The organization's applications-and data-are no longer onsite, fundamentally changing the definition of a malicious insider.\",\n \"Title: On the Performance of Byzantine Fault-Tolerant MapReduce\\nYear: 2013\\n\\nAbstract: MapReduce is often used for critical data processing, e.g., in the context of scientific or financial simulation. However, there is evidence in the literature that there are arbitrary (or Byzantine) faults that may corrupt the results of MapReduce without being detected. We present a Byzantine fault-tolerant MapReduce framework that can run in two modes: nonspeculative and speculative. We thoroughly evaluate experimentally the performance of these two versions of the framework, showing that they use around twice more resources than Hadoop MapReduce, instead of the three times more of alternative solutions. We believe this cost is acceptable for many critical applications.\",\n \"Title: Turquois: Byzantine consensus in wireless ad hoc networks\\nYear: 2010\\n\\nAbstract: The operation of wireless ad hoc networks is intrinsically tied to the ability of nodes to coordinate their actions in a dependable and efficient manner. The failure of some nodes and momentary breakdown of communications, either of accidental or malicious nature, should not result in the failure of the entire system. This paper presents Turquois - an intrusion-tolerant consensus protocol specifically de- signed for resource-constrained wireless ad hoc networks. Turquois allows an efficient utilization of the broadcasting medium, avoids synchrony assumptions, and refrains from public-key cryptography during its normal operation. The protocol is safe despite the arbitrary failure of f < n 3 pro- cesses from a total of n processes, and unrestricted mes- sage omissions. The protocol was prototyped and subject to a comparative performance evaluation against two well- known intrusion-tolerant consensus protocols. The results show that, as the system scales, Turquois outperforms the other protocols by more than an order of magnitude.\",\n \"Title: Big Data Analytics for Detecting Host Misbehavior in Large Logs\\nYear: 2015\\n\\nAbstract: The management of complex network infrastructures continues to be a difficult endeavor today. These infrastructures can contain a huge number of devices that may misbehave in unpredictable ways. Many of these devices keep logs that contain valuable information about the infrastructures' security, reliability, and performance. However, extracting information from that data is far from trivial. The paper presents a novel approach to assess the security of such an infrastructure using its logs, inspired on data from a real telecommunications network. We use machine learning and data mining techniques to analyze the data and semi-automatically discover misbehaving hosts, without having to instruct the system about how hosts misbehave.\",\n \"Title: Anticipating Requests to Improve Performance and Reduce Costs in Cloud Storage\\nYear: 2015\\n\\nAbstract: Clouds are a suitable place to store data with scalability and financial flexibility. However, it is difficult to ensure the reliability of the data stored in a cloud. Byzantine fault tolerance can improve reliability, but at a high cost. This paper presents a technique that anticipates requests in order to reduce that cost. We show that this technique improves the performance in comparison with related works and maintains the desired data reliability.\",\n \"Title: Betweenness centrality in Delay Tolerant Networks: A survey\\nYear: 2015\\n\\nAbstract: Dynamic networks, in particular Delay Tolerant Networks (DTNs), are characterized by a lack of end-to-end paths at any given instant. Because of that, DTN routing protocols employ a store-carry-and-forward approach, holding messages until a suitable node to forward them is found. But, the selection of the best forwarding node poses a considerable challenge. Additional network information (static or dynamic) can be leveraged to aid routing protocols in this troublesome task. One could use centrality metrics, therefore providing means to differentiate the importance of nodes in the network. Among these metrics, betweenness centrality is one of the most prominent, as it measures the degree to which a vertex is in a position of brokerage by summing up the fraction of shortest paths between other pairs of vertices passing through it. So, in this paper, betweenness centrality is surveyed, that is, its definitions and variants in static and dynamic networks are presented. Also, a survey of standard algorithms used to compute the metric (exact and approximate) is presented. Finally, a survey and a discussion on how DTN routing protocols make use of the betweenness centrality metric and algorithms to aid message forwarding is also presented.\",\n \"Title: Detecting and Removing Web Application Vulnerabilities with Static Analysis and Data Mining.\\nYear: 2016\\n\\nAbstract: Although a large research effort on web application security has been going on for more than a decade, the security of web applications continues to be a challenging problem. An important part of that problem derives from vulnerable source code, often written in unsafe languages like PHP. Source code static analysis tools are a solution to find vulnerabilities, but they tend to generate false posi...\",\n \"Title: Shuttle: Intrusion Recovery for PaaS\\nYear: 2015\\n\\nAbstract: The number of applications being deployed using the Platform as a Service (PaaS) cloud computing model is increasing. Despite the security controls implemented by cloud service providers, we expect intrusions to strike such applications. We present Shuttle, a novel intrusion recovery service. Shuttle recovers from intrusions in applications deployed in PaaS platforms. Our approach allows undoing changes to the state of PaaS applications due to intrusions, without loosing the effect of legitimate operations performed after the intrusions take place. We combine a record-and-replay approach with the elasticity provided by cloud offerings to recover applications deployed on various instances and backed by distributed databases. The service loads a database snapshot taken before the intrusion and replays subsequent requests, as much in parallel as possible, while continuing to execute incoming requests. We present an experimental evaluation of Shuttle on Amazon Web Services. We show Shuttle can replay 1 million requests in 10 minutes and that it can duplicate the number of requests replayed per second by increasing the number of application servers from 1 to 3.\",\n \"Title: Hacking the DBMS to Prevent Injection Attacks.\\nYear: 2016\\n\\nAbstract: After more than a decade of research, web application security continues to be a challenge and the backend database the most appetizing target. The paper proposes preventing injection attacks against the database management system (DBMS) behind web applications by embedding protections in the DBMS itself. The motivation is twofold. First, the approach of embedding protections in operating systems and applications running on top of them has been effective to protect this software. Second, there is a semantic mismatch between how SQL queries are believed to be executed by the DBMS and how they are actually executed, leading to subtle vulnerabilities in prevention mechanisms. The approach -- SEPTIC -- was implemented in MySQL and evaluated experimentally with web applications written in PHP and Java/Spring. In the evaluation SEPTIC has shown neither false negatives nor false positives, on the contrary of alternative approaches, causing also a low performance overhead in the order of 2.2%.\",\n \"Title: Greft: Arbitrary Fault-Tolerant Distributed Graph Processing\\nYear: 2015\\n\\nAbstract: Many large-scale computing problems can be modeled as graphs. Example areas include the web, social networks, and biological systems. The increasing sizes of datasets has led to the creation of various distributed large scale graph processing systems, e.g., Google Pregel. Although these systems tolerate crash faults, the literature suggests they are vulnerable to a wider range of accidental arbitrary faults (also called Byzantine faults). In this paper we present an algorithm and a prototype of a distributed large-scale graph processing system that can tolerate arbitrary faults. The prototype is based on GPS, an open source implementation of Pregel. Experimental results of the prototype in Amazon AWS are presented, showing that it uses only twice the resources of the original implementation, instead of 3-4 times as usual in Byzantine fault-tolerant systems. This cost may be acceptable for critical applications that require this level of fault tolerance.\",\n \"Title: JITeR: Just-in-time application-layer routing.\\nYear: 2016\\n\\nAbstract: The paper addresses the problem of providing message latency and reliability assurances for control traffic in wide-area IP networks. This is an important problem for cloud services and other geo-distributed information infrastructures that entail inter-datacenter real-time communication. We present the design and validation of JITeR (Just-In-Time Routing), an algorithm that timely routes messages at application-layer using overlay networking and multihoming, leveraging the natural redundancy of wide-area IP networks. We implemented a prototype of JITeR that we evaluated experimentally by placing nodes in several regions of Amazon EC2. We also present a scenario-based (geo-distributed utility network) evaluation comparing JITeR with alternative overlay/multihoming routing algorithms that shows that it provides better timeliness and reliability guarantees.\",\n \"Title: Priority-Based State Machine Replication with PRaxos\\nYear: 2016\\n\\nAbstract: State machine replication is a form of active replication commonly used to create fault-tolerant distributed services. In a nutshell, the approach consists in ensuring that a set of replicas receive and execute the same sequence of deterministic requests, returning the same results. This approach handles all requests evenly, but for some services it is important to consider that some requests have priority over others, i.e., that whenever two or more requests are ready to be executed, the one with higher priority is executed first. Paxos is perhaps the best known protocol to order requests in asynchronous environments, but Paxos has no notion of priority. In this paper we introduce the notion of priority-based state machine replication and modify Paxos to take request priorities into account. The proposed algorithm, PRaxos, works in three steps and satisfies Paxos' safety properties in asynchronous systems, while enforcing priorities when the system behaves synchronously.\",\n \"Title: DEKANT: a static analysis tool that learns to detect web application vulnerabilities.\\nYear: 2016\\n\\nAbstract: The state of web security remains troubling as web applications continue to be favorite targets of hackers. Static analysis tools are important mechanisms for programmers to deal with this problem as they search for vulnerabilities automatically in the application source code, allowing programmers to remove them. However, developing these tools requires explicitly coding knowledge about how to discover each kind of vulnerability. This paper presents a new approach in which static analysis tools learn to detect vulnerabilities automatically using machine learning. The approach uses a sequence model to learn to characterize vulnerabilities based on a set of annotated source code slices. This model takes into consideration the order in which the code elements appear and are executed in the slices. The model created can then be used as a static analysis tool to discover and identify vulnerabilities in source code. The approach was implemented in the DEKANT tool and evaluated experimentally with a set of open source PHP applications and WordPress plugins, finding 16 zero-day vulnerabilities.\",\n \"Title: Equipping WAP with WEAPONS to Detect Vulnerabilities: Practical Experience Report\\nYear: 2016\\n\\nAbstract: Although security starts to be taken into account during software development, the tendency for source code to contain vulnerabilities persists. Open source static analysis tools provide a sensible approach to mitigate this problem. However, these tools are programmed to detect a specific set of vulnerabilities and they are often difficult to extend to detect new ones. WAP is a recent popular open source tool that detects vulnerabilities in the source code of web applications written in PHP. The paper addresses the difficulty of extending these tools by proposing a modular and extensible version of the WAP tool, equipping it with \\\"weapons\\\" to detect (and correct) new vulnerability classes. The new version of the tool was evaluated with seven new vulnerability classes using web applications and plugins of the widely-adopted WordPress content management system. The experimental results show that this extensibility allows WAP to find many new (zero-day) vulnerabilities.\",\n \"Title: DARSHANA: Detecting route hijacking for communication confidentiality\\nYear: 2016\\n\\nAbstract: The Border Gateway Protocol (BGP) plays a critical role in the Internet providing connectivity to hosts across the world. Unfortunately, due to its limited security, attackers can hijack traffic by generating invalid routes. Some detection systems for route hijacking have been presented, but they require non-public information, high resources, or can easily be circumvented by attackers. We propose DARSHANA, a monitoring solution that detects route hijacking based solely on data-plane information, and has enough redundancy to prevent attacker countermeasures such as dropping of traceroute probes. DARSHANA uses active probing techniques that enable detection in near real-time. By using diverse methods, DARSHANA can still detect attacks even if the adversary manages to counter some techniques. We show that our solution allows effective detection of many hijacking attacks by emulating them using PlanetLab and Amazon AWS.\",\n \"Title: vtTLS: A vulnerability-tolerant communication protocol\\nYear: 2016\\n\\nAbstract: We present VTTLS, a vulnerability-tolerant communication protocol. There are often concerns about the strength of some of the encryption mechanisms used in SSL/TLS channels, with some regarded as insecure at some point in time. VTTLS is our solution to mitigate the problem of secure communication channels being vulnerable to attacks due to unexpected vulnerabilities in encryption mechanisms. It is based on diversity and redundancy of cryptographic mechanisms and certificates to provide a secure communication channel even when one or more mechanisms are vulnerable. VTTLS relies on a combination of k cipher suites. Even if k-1 cipher suites are insecure or vulnerable, VTTLS relies on the remaining cipher suites to maintain the channel secure. We evaluated the performance of VTTLS by comparing it to an OpenSSL channel.\",\n \"Title: MACHETE: Multi-path communication for security\\nYear: 2016\\n\\nAbstract: Communication through the Internet raises privacy and confidentiality concerns. Protocols such as HTTPS may be used to protect the communication, but occasionally vulnerabilities that may allow snooping on packet content are discovered. To address this issue, we present MACHETE, an application-layer multi-path communication mechanism that provides additional confidentiality by splitting data streams in different physical paths. MACHETE has to handle two challenges: sending packets over different paths when Internet's routing imposes a single path between pairs of network interfaces; splitting streams of data sent over TCP connections. MACHETE is the first to exploit MultiPath TCP (MPTCP) for security purposes. It leverages overlay networks and multihoming to handle the first challenge and MPTCP to handle the second. MACHETE establishes an overlay network and scatters the data over the available paths, thus reducing the effectiveness of snooping attacks. Mechanisms are provided to select paths based on path diversity.\",\n \"Title: Leveraging an homomorphic encryption library to implement a coordination service\\nYear: 2016\\n\\nAbstract: The paper presents MorphicLib, a new partial homomorphic cryptography library written in Java that can be used to implement a wide-range of applications. The paper shows the use of the library with the HomomorphicSpace coordination service. This service is a tuple space that stores encrypted tuples but still supports operations like returning tuples with values within a certain range.\",\n \"Title: Feature set tuning in statistical learning network intrusion detection\\nYear: 2016\\n\\nAbstract: The detection of security-related events using machine learning approaches has been extensively investigated. In particular, machine learning applied to network intrusion detection systems (NIDS) has attracted a lot of attention due to its good generalization and unknown attack detection capabilities. A number of classification techniques have been used for this purpose, revealing good generalization properties. In this paper we go one step further by evaluating the performance of NIDSs when feature set tuning and reduction are realized. We evaluate a number of state of the art learning algorithms that are raising much interest but have not been used for intrusion detection yet. We compare a representative set of algorithms: Ada, ROC-based learners, two types of Classification Trees, Boosted Logistic Regression, Generalized Linear Models, Gradient Boosting Machines, and Neural Networks. The main objective is to reduce the number of features used - thus also the size of the data processed - to improve speed while maintaining adequate accuracy.\",\n \"Title: State machine replication in containers managed by Kubernetes.\\nYear: 2017\\n\\nAbstract: Computer virtualization brought fast resource provisioning to data centers and the deployment of pay-per-use cost models. The system virtualization provided by containers like Docker has improved this flexibility of resource provisioning. Applications that require more restrictive agreement and ordering guarantees can also benefit from operating inside containers. This paper proposes the integration of coordination services in a container management system called Kubernetes (k8s), seeking to restrict the containers size and to offer automatic state replication. A protocol that uses shared memory available in Kubernetes was developed, and an evaluation was conducted to show the viability of the proposal.\",\n \"Title: A Systematic Approach for the Application of Restricted Boltzmann Machines in Network Intrusion Detection.\\nYear: 2017\\n\\nAbstract: A few exploratory works studied Restricted Boltzmann Machines (RBMs) as an approach for network intrusion detection, but did it in a rather empirical way. It is possible to go one step further taking advantage from already mature theoretical work in the area. In this paper, we use RBMs for network intrusion detection showing that it is capable of learning complex datasets. We also illustrate an integrated and systematic way of learning. We analyze learning procedures and applications of RBMs and show experimental results for training RBMs on a standard network intrusion detection dataset.\",\n \"Title: Chrysaor: Fine-Grained, Fault-Tolerant Cloud-of-Clouds MapReduce.\\nYear: 2017\\n\\nAbstract: MapReduce is a framework for processing large data sets much used in the context of cloud computing. MapReduce implementations like Hadoop can tolerate crashes and file corruptions, but not arbitrary faults. Unfortunately, there is evidence that arbitrary faults do occur and can affect the correctness of MapReduce job executions. Furthermore, many outages of major cloud offerings have been reported, raising concerns about the dependence on a single cloud. In this paper we propose a novel execution system that allows to scale out MapReduce computations to a cloud-of-clouds and tolerate arbitrary faults, malicious faults, and cloud outages. Our system, Chrysaor, is based on a fine-grained replication scheme that tolerates faults at the task level. Our solution has three important properties: it tolerates the above-mentioned classes of faults at reasonable cost; it requires minimal modifications to the users' applications; and it does not involve changes to the Hadoop source code. We performed an extensive evaluation of our system in Amazon EC2, showing that our fine-grained solution is efficient in terms of computation by recovering only faulty tasks. This is achieved without incurring a significant penalty for the baseline case (i.e., without faults) in most workloads.\",\n \"Title: Light-SPD: a platform to prototype secure mobile applications\\nYear: 2016\\n\\nAbstract: Securely storing sensitive personal data is critical for protecting privacy. Currently, many persons use smartphones to store their private data. However, smartphones suffer from many security issues. To overcome this situation, the PCAS project is designing a secure personal storage device called the Secure Portable Device (SPD), to be attached to a smartphone for securely storing sensitive personal data. However, this device is unavailable, closed, and expensive to deploy for prototyping applications. We propose a platform that emulates the SPD and the smartphone using a board with an ARM processor with the TrustZone security extension. This platform is open, inexpensive, and secure. A payment application is used as an example to show the platform's capabilities. As a proof-of-concept, we implemented this platform and provide a performance evaluation using a i.MX53 board.\",\n \"Title: T2Droid: A TrustZone-Based Dynamic Analyser for Android Applications\\nYear: 2017\\n\\nAbstract: Android has become the most widely used mobile operating system (OS) in recent years. There is much research on methods for detecting malicious Android applications. Dynamic analysis methods detect such applications by evaluating their behaviour during execution. However, such mechanisms may be ineffective as malware is often able to disable antimalware software. This paper presents the design of T2DROID, a dynamic analyser for Android that uses traces of Android API function calls and kernel syscalls, and that is protected from malware by leveraging the ARM TrustZone security extension. In our experimental evaluation T2DROID achieved accuracy and precision of 0.98 and 0.99, respectively, with a kNN classifier.\",\n \"Title: REPSYS: A Robust and Distributed Reputation System for Delay-Tolerant Networks.\\nYear: 2017\\n\\nAbstract: Distributed reputation systems can be used to foster cooperation between nodes in decentralized and self-managed systems due to the nonexistence of a central entity. In this paper, a Robust and Distributed Reputation System for Delay-Tolerant Networks (REPSYS) is proposed. REPSYS is robust because despite taking into account first- and second-hand information, it is resilient against false accusations and praise, and distributed, as the decision to interact with another node depends entirely on each node. Simulation results show that the system is capable, while evaluating each node's participation in the network, to detect on the fly nodes that do not accept messages from other nodes and that disseminate false information even while colluding with others, and while evaluating how honest is each node in the reputation system, to classify correctly nodes in most cases.\",\n \"Title: Consistency Of Surface Electromyography Assessment At Lower Limb Selected Muscles During Vertical Countermovement\\nYear: 2017\\n\\nAbstract: Given the difficulty of invasive methods to assess muscle action during natural human movement, surface electromyography (sEMG) has been increasingly used to capture muscle activity in relation to kinesiological analysis of specific tasks. Isolated isometric, concentric and eccentric forms of muscle action have been receiving the most attention for research purposes. Nevertheless natural muscle action frequently involves the use of a preceding eccentric muscle action as a form of potentiation of immediate muscle concentric action, in what is designated as muscle stretch-shortening cycle (SSC). The most frequently applied protocols for the evaluation of SSC on vertical jumps are by virtue of their reproducibility and control of experimental conditions, squat jump (SJ) without countermovement (CM), countermovement jump (CMJ) with long CM and drop jump (DJ) with short CM. The methods used to extract information and relationship of the captured signals also present a high diversity, with the question about the consistency of the methods and obtained results. The objective of this study is to evaluate the consistency of the analysis and results by applying different EMGs signal analysis techniques related to strategic muscle groups of the lower limbs at different countermovement evaluated in vertical jumps. Raw sEMG signals of 5 lower limb muscles of 6 subjects during SJ, CMJ and DJ were rectified, filtered and obtained their envelope, and then correlated (CR) for detection of synergistic, agonist and antagonist activity, applied principal component analysis (PCA) for the detection of uncorrelated components explaining maximum variability and normalized cross-correlation (CCRN) for detection of maximum correlations and time lag. CR of EMG envelopes presented higher coactivities (CoA) in DJ relative to SJ and these CoA superior to CMJ with greater synergy in DJ relative to SJ and CMJ that present several loop cycles corresponding to time lag of activity. CCRN of the EMG envelopes presented also higher CoA in DJ when compared to SJ and both higher CoA to CMJ. PCA allowed to detect a principal component (PC) explaining 92.2% of the variability of EMG in DJ, 90.6% in SJ and 78.7% in CMJ, the second PC responsible for the explanation of 4.9% variability in DJ, 6.7% in SJ and 15.3% in CMJ.\",\n \"Title: Xor-Overlay Topology Management beyond Kademlia.\\nYear: 2017\\n\\nAbstract: Kademlia is a widely successful Distributed Hash Table (DHT) implementation, better known for its use in the BitTorrent protocol. In this paper, we revisit its overlay management separately from the DHT operations to allow it to be used with other distributed abstractions by providing an accurate and consistent view of the k-closest nodes to any given identifier. We then present invariants that avoid the irregularities that are necessary with the original k-bucket design and improve on later published solutions by not needing an additional parameter to tune. We then provide a specification of a distributed abstraction that provides the automatic management of routing tables using our invariants and a pseudo-code implementation of that abstraction. We finally sketch how our abstraction may be used for a security mechanism and how it could be combined with other known distributed abstractions to provide other services than file sharing in xor-based overlay networks enabling xor-based network overlays to go beyond their original Kademlia design.\",\n \"Title: Demonstrating a Tool for Injection Attack Prevention in MySQL\\nYear: 2017\\n\\nAbstract: Despite the significant efforts put in building more secure web applications, cases of high impact breaches continue to appear. Vulnerabilities in web applications are often created due to inconsistencies in the way SQL queries are believed to be run and the way they are actually executed by a Database Management System (DBMS). This paper presents a demonstration of SEPTIC, a mechanism that detects and blocks injection attacks inside the DBMS. The demonstration considers a scenario of a non-trivial PHP web application, backed by a MySQL DBMS, which was modified to include SEPTIC. It presents how SEPTIC blocks injection attacks without compromising the application correctness and performance. In addition, SEPTIC is compared to alternative approaches, such as sanitizations carried out with standard functions provided language and a web application firewall.\",\n \"Title: On the Design of Resilient Multicloud MapReduce.\\nYear: 2017\\n\\nAbstract: Faced with the challenge of dependability, we have recently explored multicloud solutions to increase the resilience and availability of MapReduce. Based on this experience, we present system design guidelines that allow the scaling out of MapReduce computation to multiple clouds to tolerate arbitrary and malicious faults, as well as cloud outages. Crucially, the techniques we introduce have reaso...\",\n \"Title: On Combining Diverse Static Analysis Tools for Web Security: An Empirical Study\\nYear: 2017\\n\\nAbstract: Developers frequently rely on free static analysis tools to automatically detect vulnerabilities in the source code of their applications, but it is well-known that the performance of such tools is limited and varies from one software development scenario to another, both in terms of coverage and false positives. Diversity is an obvi-ous direction to take to improve coverage, as different tools usual-ly report distinct vulnerabilities, but this may come with an in-crease in the number of false alarms. In this paper, we study the problem of combining diverse static analysis tools to detect web vulnerabilities, considering four software development scenarios with different goals and constraints, ranging from low budget to high-end (e.g., business critical) applications. We conducted an experimental campaign with five free static analysis tools to detect vulnerabilities in a workload composed by 134 WordPress plugins. Results clearly show that the best solution depends on the development scenario. Furthermore, in some cases, a single tool performs better than the best combination of tools.\",\n \"Title: Rectify: black-box intrusion recovery in PaaS clouds.\\nYear: 2017\\n\\nAbstract: Web applications hosted on the cloud are exposed to cyberattacks and can be compromised by HTTP requests that exploit vulnerabilities. Platform as a Service (PaaS) offerings often provide a backup service that allows restoring application state after a serious attack, but all valid state changes since the last backup are lost. We propose Rectify, a new approach to recover from intrusions on applications running in a PaaS. Rectify is a service designed to be deployed alongside the application in a PaaS container. It does not require modifications to the software and the recovery can be performed by a system administrator. Machine learning techniques are used to associate the requests received by the application to the statements issued to the database. Rectify was evaluated using three widely used web applications - Wordpress, LimeSurvey and MediaWiki - and the results show that the effects of malicious requests can be removed whilst preserving the valid application data.\",\n \"Title: REPSYS: A Robust and Distributed Incentive Scheme for Collaborative Caching and Dissemination in Content-Centric Cellular-Based Vehicular Delay-Tolerant Networks.\\nYear: 2018\\n\\nAbstract: In this article, a robust and distributed incentive scheme for collaborative caching and dissemination in content-centric cellular-based vehicular delay-tolerant networks (REPSYS) is proposed. REPSYS is robust because despite taking into account first- and second-hand information, it is resilient against false accusations and praise, and distributed, as the decision to interact with another node d...\",\n \"Title: Introspection for ARM TrustZone with the ITZ Library\\nYear: 2018\\n\\nAbstract: TrustZone is an extension of the ARM architecture that allows software executed in ARM processors to be split in two environments: the normal world that runs a common operating system (e.g., Android or Linux) and its applications, and the secure world that runs security services or others that need to be isolated from the normal world. This work aims to provide support for analyzing the security status of the normal world from the secure world. For this purpose, we present a Virtual Machine Introspection (VMI) library that leverages the TrustZone architecture. VMI tools and the library run in the secure world and inspect the normal world. We present an experimental evaluation of the library in an i.MX53 development board.\",\n \"Title: FlowHacker: Detecting Unknown Network Attacks in Big Traffic Data Using Network Flows\\nYear: 2018\\n\\nAbstract: Traditional Network Intrusion Detection Systems (NIDSs) inspect the payload of the packets looking for known intrusion signatures or deviations from normal behavior, but inspecting traffic at the current speed of Internet Service Provider (ISP) networks is difficult or even unfeasible. This paper presents an approach to detect malicious traffic and identify malicious hosts by inspecting flows, leveraging a combination of unsupervised machine learning and threat intelligence, without requiring either previous knowledge about attacks or traffic without attacks. The approach was implemented in the FlowHacker NIDS and evaluated with two kinds of traffic flows: synthetic traffic flows and real ISP traffic flows.\",\n \"Title: Benchmarking Static Analysis Tools for Web Security.\\nYear: 2018\\n\\nAbstract: Static analysis tools are recurrently used by developers to search for vulnerabilities in the source code of web applications. However, distinct tools provide different results depending on factors such as the complexity of the code under analysis and the application scenario; thus, missing some of the vulnerabilities while reporting false problems. Benchmarks can be used to assess and compare dif...\",\n \"Title: Generalized Lower Limb Joint Angular Phase Space Analysis of Subject Specific Normal and Modified Gait.\\nYear: 2018\\n\\nAbstract: This study presents and applies generalized angular phase space analysis to lower limb joint angles of specific subject during normal and modified gait for discrimination of gait and joint angular movements. Case study of an adult healthy male in-vivo and noninvasive kinematic assessment of skin surface adhesive markers at lower limb was performed at human movement lab during normal gait, stiff knee gait and slow running. Musculoskeletal modeling was performed using AnyGait v.0.92 morphing Twente Lower Extremity Model (TLEM) to match the size and joint morphology of the stick-figure model. Inverse kinematics was performed obtaining hip, knee and ankle joint flexion-extension angular displacements, velocities and accelerations. Generalized phase space analysis was applied to lower limb joint angular displacements, velocities and accelerations. Directional statistics was applied to generalized phase planes with mean direction, resultant length and circular standard deviation assessment. Rayleigh test was employed for directional concentration and coordination assessment, and Watson's $\\\\mathrm{U^{2$ goodness of fit test applied to the von Mises distribution. Results point for the importance of subject specific study, generalized joint angular phase space analysis, comparing results with other normalization methods and validation of applied methods with qualitative clinical analysis.\",\n \"Title: RockFS: Cloud-backed File System Resilience to Client-Side Attacks.\\nYear: 2018\\n\\nAbstract: Cloud-backed file systems provide on-demand, high-availability, scalable storage. Their security may be improved with techniques such as erasure codes and secret sharing to fragment files and encryption keys in several clouds. Attacking the server-side of such systems involves penetrating one or more clouds, which can be extremely difficult.\\n\\nDespite all these benefits, a weak side remains: the client-side. The client devices store user credentials that, if stolen or compromised, may lead to confidentiality, integrity, and availability violations. In this paper we propose RockFS, a cloud-backed file system framework that aims to make the client-side of such systems resilient to attacks. RockFS protects data in the client device and allows undoing unintended file modifications.\",\n \"Title: Leveraging Arm Trustzone And Verifiable Computing To Provide Auditable Mobile Functions\\nYear: 2018\\n\\nAbstract: The increase of personal data on mobile devices has been followed by legislation that forces service providers to process and maintain users' data under strict data protection policies. In this paper, we propose a new primitive for mobile applications called auditable mobile function (AMF) to help service providers enforcing such policies by enabling them to process sensitive data within users' devices and collecting proofs of function execution integrity. We present SafeChecker, a computation verification system that provides mobile application support for AMFs, and evaluate the practicality of different usage scenario AMFs on TrustZone-enabled hardware.\",\n \"Title: An empirical study on combining diverse static analysis tools for web security vulnerabilities based on development scenarios\\nYear: 2019\\n\\nAbstract: Automated Static Analysis Tool (ASATs) are one of the best ways to search for vulnerabilities in applications, so they are a resource widely used by developers to improve their applications. However, it is well-known that the performance of such tools is limited, and their detection capabilities may not meet the requirements of the project regarding the criticality of the application. Diversity is an obvious direction to take to improve the true positives, as different tools usually report distinct vulnerabilities, however with the cost of also increasing the false positives, which may be unacceptable in some scenarios. In this paper, we study the problem of combining diverse ASATs to improve the overall detection of vulnerabilities in web applications, considering four development scenarios with different criticality goals and constraints. These scenarios range from low budget to high-end (e.g., business critical) web applications. We tested with five ASATs under two datasets, one with real WordPress plugins and another with synthetic test cases. Our findings revealed that combining the outputs of several ASATs does not always improve the vulnerability detection performance over a single ASAT. By using our procedure a developer is able to choose which is the best combination of ASATs that fits better in the project requirements.\",\n \"Title: NoSQL Undo: Recovering NoSQL databases by undoing operations\\nYear: 2016\\n\\nAbstract: NoSQL databases offer high throughput, support for huge data structures, and capacity to scale horizontally at the expense of not supporting relational data, ACID consistency and a standard SQL syntax. Due to their simplicity and flexibility, NoSQL databases are becoming very popular among web application developers. However, most NoSQL databases only provide basic backup and restore mechanisms, which allow recovering databases from a crash, but not to remove undesired operations caused by accidental or malicious actions. To solve this problem we propose NOSQL UNDO, a recovery approach and tool that allows database administrators to remove the effect of undesirable actions by undoing operations, leading the system to a consistent state. NOSQL UNDO leverages the logging and snapshot mechanisms built-in NoSQL databases, and is able to undo operations as long as they are present in the logs. This is, as far as we know, the first recovery service that offers these capabilities for NoSQL databases. The experimental results with MongoDB show that it is possible to undo a single operation in a log with 1,000,000 entries in around one second and to undo 10,000 incorrect operations in less than 200 seconds.\",\n \"Title: ePRIVO: An Enhanced PRIvacy-preserVing Opportunistic Routing Protocol for Vehicular Delay-Tolerant Networks.\\nYear: 2018\\n\\nAbstract: This paper proposes an enhanced PRIvacy preserVing opportunistic routing protocol (ePRIVO) for vehicular delay-tolerant networks (VDTN). ePRIVO models a VDTN as a time-varying neighboring graph where edges correspond to neighboring relationship between pairs of vehicles. It addresses the problem of vehicles taking routing decision meanwhile keeping their information private, i.e., vehicles compute...\",\n \"Title: Pando: Personal Volunteer Computing in Browsers.\\nYear: 2019\\n\\nAbstract: The large penetration and continued growth in ownership of personal electronic devices represents a freely available and largely untapped source of computing power. To leverage those, we present Pando, a new volunteer computing tool based on a declarative concurrent programming model and implemented using JavaScript, WebRTC, and WebSockets. This tool enables a dynamically varying number of failure-prone personal devices contributed by volunteers to parallelize the application of a function on a stream of values, by using the devices' browsers. We show that Pando can provide throughput improvements compared to a single personal device, on a variety of compute-bound applications including animation rendering and image processing. We also show the flexibility of our approach by deploying Pando on personal devices connected over a local network, on Grid5000, a French-wide computing grid in a virtual private network, and seven PlanetLab nodes distributed in a wide area network over Europe.\",\n \"Title: SEPTIC: Detecting Injection Attacks and Vulnerabilities Inside the DBMS\\nYear: 2019\\n\\nAbstract: Databases continue to be the most commonly used backend storage in enterprises, but they are often integrated with vulnerable applications, such as web frontends, which allow injection attacks to be performed. The effectiveness of such attacks stems from a semantic mismatch between how SQL queries are believed to be executed and the actual way in which databases process them. This leads to subtle vulnerabilities in the way input validation is done in applications. In this paper, we propose SEPTIC, a mechanism for DBMS attack prevention, which can also assist on the identification of the vulnerabilities in the applications. The mechanism was implemented in MySQL and evaluated experimentally with various applications and alternative protection approaches. Our results show no false negatives and no false positives with SEPTIC, on the contrary to other solutions. They also show that SEPTIC introduces a low performance overhead, in the order of 2.2%.\",\n \"Title: Genet: A Quickly Scalable Fat-Tree Overlay for Personal Volunteer Computing using WebRTC\\nYear: 2019\\n\\nAbstract: The following topics are dealt with: multi-agent systems; learning (artificial intelligence); decision making; cloud computing; Internet of Things; Bayes methods; configuration management; psychology; interactive systems; software agents.\",\n \"Title: Secure cloud-of-clouds storage with space-efficient secret sharing\\nYear: 2021\\n\\nAbstract: Cloud storage services are top-rated, but there are often concerns about the security of the files there stored. Clouds-of-clouds or multi-clouds are being explored in order to improve that security. The idea is to store the files in several clouds, ensuring integrity and availability. Confidentiality, however, is obtained by encrypting the files with block ciphers that do not provide provable security. Secret sharing allows distributing files among the clouds providing information-theoretic security/secrecy. However, existing secret sharing schemes are space-inefficient (the size of the shares is much larger than the size of the secret) or purely theoretical. In this paper, we propose the first practical space-efficient secret sharing scheme that provides information-theoretic security, which we denominate PRactical Efficient Secret Sharing (PRESS). Moreover, we present the Secure CloUD storage (SCUD) service, a new cloud-of-clouds storage service that leverages PRESS to provide file confidentiality. Additionally, SCUD provides data integrity and availability, leveraging replication.\",\n \"Title: Omega: A Secure Event Ordering Service for the Edge\\nYear: 2022\\n\\nAbstract: The edge computing paradigm extends cloud computing with storage and processing capacity close to the edge of the network, which can be materialized by using many fog nodes placed in multiple geographic locations. Fog nodes are likely to be vulnerable to tampering, so it is important to protect the functions they provide from attacks. A key building block of many distributed applications is an ordering service that keeps track of cause-effect dependencies among events and that allows events to be processed in an order that respects causality. This article presents the design and implementation of a secure event ordering service for fog nodes. Our service, named Omega, leverages the availability of a Trusted Execution Environment (TEE), based on SGX technology, to offer fog clients guarantees regarding the order in which events are applied and served, even when fog nodes are compromised. We have also built OmegaKV, a key-value store that uses Omega to offer causal consistency. Experimental results show that the ordering service can be secured without violating the latency constraints of time-sensitive edge applications, despite the overhead associated with using a TEE. Omega introduces an additional latency of approximately 4ms, that contrary to cloud based solutions, allows latency values in the 5ms-30ms range, as required by time-sensitive edge applications.\",\n \"Title: Enabling Cross-Jurisdiction Digital Asset Transfer\\nYear: 2021\\n\\nAbstract: Enabling blockchain-based digital asset exchanges requires blockchain interoperability capabilities. Although some solutions have been proposed in recent years, asset and crypto-currency transfers across legal jurisdictions are still an unsolved problem. To realize this vision, we propose Hermes, a fault-tolerant middleware that connects blockchain networks, enabling the transfer of data and value...\",\n \"Title: Fractal Brownian Motion Assessment of the Center of Pressure Excursion During Impulse Phase on Standard Vertical Jump\\nYear: 2021\\n\\nAbstract: This study presents and applies fractal Brownian motion assessment of the center of pressure (COP) excursion during feet ground contact on standard vertical jump impulse phase with long and short countermovement (CM) in relation with lower limb muscle stretch-shortening cycle (SSC) comparing it with no CM and SSC. Fifty-four tests were performed by a group of six healthy male students of sports and physical education degree without previous injury, specific training, or fitness ability. Three repetitions were performed by each subject of a squat jump (SJ) without CM and SSC, countermovement jump (CMJ) with long CM and SSC, as well as drop jump (DJ) with short CM and SSC after depth jump from a 40 cm step. During trial tests ground reaction force and force moments were acquired with force platform and impulse phases were segmented for COP coordinates computation. Fractal Brownian motion analysis of COP excursion during impulse phases conduced to detection of differences between critical time and displacement as well as short and long-term diffusion coefficient (Ds, Dl) and Hurst index scale exponent (Hs, Hl), with Ds, Dl presenting statistical significative correlations -0.491, -0.559 and Hs, Hl non statistical significative correlations 0.266 and -0.424 with MVJ height (ht) at 5% significance for explaining underlying mechanisms on CM and SSC at MVJ. Clinical Relevance- This work contributes with new method for the study expansion of the center of pressure excursion and stability during feet ground contact from orthostatic standing position to the impulse phase during standard maximum vertical jump as the most adequate method for assessment of lower limb muscle stretch-shortening cycle.\",\n \"Title: Hermes: Fault-tolerant middleware for blockchain interoperability\\nYear: 2022\\n\\nAbstract: Blockchain interoperability reduces the risk of investing in blockchain systems by avoiding vendor lock-in, enabling a new digital economy, and providing migration capabilities. However, seamless interoperability among enterprises requires service providers to comply with different regulations, e.g., data privacy regulations and others that apply to financial services. For supporting interoperability, organizations can connect to each blockchain via a gateway. However, these gateways should be resilient to crashes to maintain a consistent state across ledgers. To realize this vision, we propose Hermes, a fault-tolerant middleware that connects blockchain networks and is based on the Open Digital Asset Protocol (ODAP). Hermes is crash fault-tolerant by allying a new protocol, ODAP-2PC, with a log storage API that can leverage blockchain to secure logs, providing transparency, auditability, availability, and non-repudiation. We briefly explore a use case for cross-jurisdiction asset transfers, illustrating how one can leverage Hermes to support cross-chain transactions compliant with legal and regulatory frameworks.\",\n \"Title: CyberVTI: Cyber Visualization Tool for Intrusion Detection\\nYear: 2021\\n\\nAbstract: This paper presents the Cyber Visualization Tool for Intrusion detection (CYBERVTI), a tool that provides intrusion detection algorithms with an effective graphical interface. The goals of the tool are twofold. First, it aims to aid the human analyst on observing ongoing threats as a step towards responding to these attacks. Second, it aims to help the analyst study the performance of the algorithms with different parameters, in order to decide which combination best suits his goals. The tool integrates a set of recently-proposed intrusion detection algorithms based on unsupervised machine learning, which it aims to help configuring. Cybervti follows a client-server system architecture and implements a REST API that mediates the communication between the server and the GUI on the client-side. A significant challenge is to define data structures that allow storing and accessing data efficiently in an interactive manner. A clear and minimalist visual aspect was chosen for the GUI, containing functionalities that enable the user to analyze the network data in a simple and clear way. For system evaluation, we used the ISOIIEC 25010:2011 requirements. For validation, we compared the results obtained by our tool with the results described in the original papers that present the algorithms.\",\n \"Title: SRX-Secure Data Backup and Recovery for SGX Applications\\nYear: 2022\\n\\nAbstract: Intel SGX improves the security of applications by shielding code and data from untrusted software in enclaves. Since enclaves lose their state when closed, that state has to be sealed, i.e., cryptographically protected with a secret key, and stored outside the enclave boundary. In SGX, the used key is bound to both the enclave and the processor that sealed the data, so it is unfeasible for any enclave in another computer to derive the same secret key to unseal such data. This offers security to the data, but also makes it impossible to recover that data if the original computer is damaged or stolen. In order to support backup and recovery of data sealed by enclaves, we propose SRX, a solution for sharing sealed data amongst a restricted set of SGX-enabled computers executing the same enclave code. Enclaves using SRX have access to common keys to seal and unseal enclave data, allowing the sharing of sealed data among the trusted domain. SRX guarantees that these secret keys are never exposed outside the trusted domain. SRX was implemented and evaluated with two applications: a bitcoin wallet and a password manager.\",\n \"Title: A survey on business process view integration: past, present and future applications to blockchain\\nYear: 2022\\n\\nAbstract: Purpose The complexity of business environments often causes organizations to produce several inconsistent views of the same business process (BP), leading to fragmentation. BP view integration attempts to produce an integrated view from different views of the same model, facilitating the management of BP models. Design/methodology/approach To study the trends of BP view integration, the authors conduct an extensive and systematic literature review to summarize findings since the 1970s. With a starting corpus of 918 documents, this survey draws up a systematic inventory of solutions used in academia and industry. By narrowing it down to 71 articles, the authors discuss in-depth 17 BP integration techniques papers, classifying each solution according to 9 criteria. Findings The authors' study shows that most view-integration methods (11) utilize annotation-based matching, based on formal merging rules. While most solutions are formalized, only approximately half are validated with a real-world use case scenario. View integration can be applied to areas other than database schema integration and BP view integration. Practical implications By summarizing existing knowledge up to June 2021, the authors explore possible future research directions. The authors highlight the application of view integration to the blockchain research area, where stakeholders can have different views on the same blockchain. The authors expect that this study contributes to interdisciplinary research across view integration, namely to the context of blockchain. Originality/value This survey serves to pave the way for future trends, where the authors highlight the application of view integration to blockchain research.\",\n \"Title: Fingerprinting for Web Applications: From Devices to Related Groups\\nYear: 2016\\n\\nAbstract: Identifying users and user devices is as important in web applications as in many other contexts. In web applications, user identification usually involves an authentication process, e.g., providing a username and a password. Identification is also possible without explicit authentication using cookies or device fingerprints. Device fingerprinting is also useful for other purposes, e.g., to serve as a second factor of authentication. Recently some interest appeared in the problem of cross-device fingerprinting, i.e., of the identification of the same user in different devices using fingerprinting. We target a variation of the problem that we call related group fingerprinting. We define a related group as a set of persons (e.g., a family) that share the same home network. We devised a related group fingerprinting scheme that we evaluated experimentally with data from hundreds of users. This evaluation suggests that group fingerprinting is feasible.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":110,"string":"110"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":285,"string":"285"}}},{"rowIdx":286,"cells":{"question_id":{"kind":"string","value":"Han Ren"},"question":{"kind":"string","value":"Generate an abstract for the title \"Statistics-based Semantic Role Labeling for Chinese menu corpus\" using the following items: 1. Automatic Semantic Role Labeling\n2. Chinese-specific corpus\n3. Ontology for Chinese word segmentation\n4. Statistical methods for labeling\n5. Good performance achieved."},"answer":{"kind":"string","value":"This paper describes our attempt at automatic Semantic Role Labeling for a Chinese specific corpus. We present a method to construct a domain specific corpus, a set of semantic roles that we will use, and their annotation. Additionally, we construct an ontology that we use in order to improve the accuracy of Chinese word segmentation and unknown word recognition. We propose two statistical methods for Semantic Role labeling and carry out experiments to compare them, and experimental results show that the methods achieve good performance."},"correct_answer":{"kind":"string","value":"This paper describes our attempt at automatic Semantic Role Labeling for a Chinese specific corpus. We present a method to construct a domain specific corpus, a set of semantic roles that we will use, and their annotation. Additionally, we construct an ontology that we use in order to improve the accuracy of Chinese word segmentation and unknown word recognition. We propose two statistical methods for Semantic Role labeling and carry out experiments to compare them, and experimental results show that the methods achieve good performance."},"documents":{"kind":"list like","value":["Title: A web knowledge based approach for complex question answering\nYear: 2011\n\nAbstract: Current researches on Question Answering concern more complex questions than factoid ones. Since complex questions are investigated by many researches, how to acquire accurate answers still becomes a core problem for complex QA. In this paper, we propose an approach that estimates the similarity by topic model. After summarizing relevant texts from web knowledge bases, an answer sentence acquisition model based on Probabilistic Latent Semantic Analysis is introduced to seek sentences, in which the topic is similar to those in definition set. Then, an answer ranking model is employed to select both statistically and semantically similar sentences between sentences retrieved and sentences in the relevant text set. Finally, sentences are ranked as answer candidates according to their scores. Experiments show that our approach achieves an increase of 5.19% F-score than the baseline system.","Title: Enumeration of 2-connected loopless 4-regular maps on the plane\nYear: 2002\n\nAbstract: In this paper rooted (near-) 4-regular maps on the plane are counted with respect to the root-valency, the number of edges, the number of inner faces, the number of non-root vertex loops, the number of non-root vertex blocks, and the number of multi-edges. As special cases, formulae of several types of rooted 4-regular maps such as 2-connected 4-regular planar maps, rooted 2-connected (connected) 4-regular planar maps without loops are also presented. Several known results on 4-regular maps and trees of Tutte are also concluded. Finally, asymptotic formulae for the numbers of those types of maps are given.","Title: Enumerative Properties of Rooted Circuit Maps\nYear: 2010\n\nAbstract: In 1966, Barnette introduced a set of graphs, called circuit graphs, which are obtained from 3-connected planar graphs by deleting a vertex. Circuit graphs and 3-connected planar graphs share many interesting properties which are not satisfied by general 2-connected planar graphs. Circuit graphs have nice closure properties which make them easier to deal with than 3-connected planar graphs for studying some graph-theoretic properties. In this paper, we study some enumerative properties of circuit graphs. For enumeration purpose, we define rooted circuit maps and compare the number of rooted circuit maps with those of rooted 2-connected planar maps and rooted 3-connected planar maps.","Title: Finding Answers to Definition Questions Using Web Knowledge Bases.\nYear: 2009\n\nAbstract: Current researches on Question Answering concern more complex questions than factoid ones. Since definition questions are investigated by many researches, how to acquire accurate answers still becomes a core problem for definition QA. Although some systems use web knowledge bases to improve answer acquisition, we propose an approach that leverage them in an effective way. After summarizing definitions from web knowledge bases and merge them to a definition set, a two-stage retrieval model based on Probabilistic Latent Semantic Analysis is produced to seek documents and sentences in which the topic is similar to those in definition set. Then, an answer ranking model is employed to select both statistically and semantically similar sentences between sentences retrieved and sentences in definition set. Finally, sentences are ranked as answer candidates according to their scores. Experiments indicate following conclusions: 1) specific summarization technologies improves definition QA systems to a better performance; 2) topic based models can be more helpful than centroid-based models for definition QA systems in solving synonym and data sparse problems; 3) shallow semantic analysis is effective to find discriminative characteristics of definitions automatically. © 2009 by Han Ren, Donghong Ji, Jing Wan, and Chong Teng.","Title: Maximum Genus Embeddings and Genus Embeddings on Orientable Surfaces.\nYear: 2013\n\nAbstract: In this paper, the estimations of maximum genus orientable embeddings of graphs are studied, and an exponential lower bound for such numbers are found. Moreover, such two extremal embeddings (i.e., the maximum genus orientable embedding of the current graph and the minimum genus orientable embedding of the complete graph) are sometimes closely related with each other. As applications, we estimate the number of the minimum genus orientable embeddings for complete graph, by estimating the number of maximum genus orientable embedings for current graph.","Title: Exponentially Many Monochromatic n-Matchings in K 3n-1\nYear: 2012\n\nAbstract: Erdös et al and Gerencsér et al had shown that in any 2-edge-coloring of K 3n-1, there is a n-matching containing edges with the same color(we call such matching monochromatic matching). In this paper we show that for any 2-edge-coloring of K 3n-1 there exists a monochromatic subgraph H of K 3n-1 which contains exponentially many monochromatic n-matchings.","Title: Automatic Chinese Catchword Extraction Based on Time Series Analysis.\nYear: 2008\n\nAbstract: Catchwords refer to those popular words or phrases in a time period. In this paper, we propose a novel approach for automatic extraction of Chinese catchwords. By analyzing features of catchwords, we define three aspects to describe Popular Degree of catchwords. Then we use curve fitting in Time Series Analysis to build Popular Degree Curves of the extracted terms. Finally we give a formula that can calculate Popular Degree values of catchwords and get a ranking list of catchword candidates. Experiments show that the method is effective.","Title: Lower bound on the number of the maximum genus embedding of Kn, n.\nYear: 2013\n\nAbstract: In this paper, we provide a method to obtain the lower bound on the number of the distinct maximum genus embedding of the complete bipartite graph K-n,K-n (n is an odd number), which, in some sense, improves the results of S. Stahl and H. Ren.","Title: The number of loopless 4-regular maps on the projective plane\nYear: 2002\n\nAbstract: In this paper rooted loopless (near) 4-regular maps on surfaces such as the sphere and the projective plane are counted and exact formulae with up to three or four parameters for such maps are given. Several classical results on regular maps and one-faced maps are deduced.","Title: Parsing Syntactic and Semantic Dependencies for Multiple Languages with A Pipeline Approach.\nYear: 2009\n\nAbstract: This paper describes a pipelined approach for CoNLL-09 shared task on joint learning of syntactic and semantic dependencies. In the system, we handle syntactic dependency parsing with a transition-based approach and utilize MaltParser as the base model. For SRL, we utilize a Maximum Entropy model to identify predicate senses and classify arguments. Experimental results show that the average performance of our system for all languages achieves 67.81% of macro F1 Score, 78.01% of syntactic accuracy, 56.69% of semantic labeled F1, 71.66% of macro precision and 64.66% of micro recall.","Title: Vertex Splitting and Upper Embeddable Graphs\nYear: 2012\n\nAbstract: The weak minor G of a graph G is the graph obtained from G by a sequence of edge-contraction operations on G. A weak-minor-closed family of upper embeddable graphs is a set G of upper embeddable graphs that for each graph G in G, every weak minor of G is also in G. Up to now, there are few results providing the necessary and sufficient conditions for characterizing upper embeddability of graphs. In this paper, we studied the relation between the vertex splitting operation and the upper embeddability of graphs; provided not only a necessary and sufficient condition for characterizing upper embeddability of graphs, but also a way to construct weak-minor-closed family of upper embeddable graphs from the bouquet of circles; extended a result in J: Graph Theory obtained by L. Nebesk{\\P}y. In addition, the algorithm complex of determining the upper embeddability of a graph can be reduced much by the results obtained in this paper.","Title: Enumerating near-4-regular maps on the sphere and the torus\nYear: 2001\n\nAbstract: In this paper rooted near-4-regular maps on the plane and the torus are counted with formulae with respect to four parameters: the root valency, the number of edges, the inner faces, and nonroot-vertex loops. In particular, the number of rooted near-4-regular maps on those surfaces with exactly k nonroot-vertex loops is investigated.","Title: Homeomorphically irreducible spanning trees in locally connected graphs\nYear: 2012\n\nAbstract: A spanning tree T of a graph G is called a homeomorphically irreducible spanning tree (HIST) if T does not contain vertices of degree 2. A graph G is called locally connected if, for every vertex v ∈ V(G), the subgraph induced by the neighbourhood of v is connected. In this paper, we prove that every connected and locally connected graph with more than 3 vertices contains a HIST. Consequently, we confirm the following conjecture due to Archdeacon: every graph that triangulates some surface has a HIST, which was proposed as a question by Albertson, Berman, Hutchinson and Thomassen.","Title: Generating cycle spaces for graphs on surfaces with small genera\nYear: 2004\n\nAbstract: In this paper we investigate cycle base structures of a 2-(edge)-connected graph on surfaces with small genera and show that short cycles do generate the cycle spaces in the case of \"small face-embeddings\". Examples show that the conditions in our main results are best possible. As applications we find the exact formulae for the minimum lengths of cycle bases of some types of graphs which conclude several known results. Finally, we generalize those results for graphs embedded on general orientable surfaces.","Title: Semi-automatic hot event detection\nYear: 2006\n\nAbstract: In this paper, we propose a method to detect hot event automatically. We use all the web pages from Jan 1st 2005 to Dec 31st 2005, and detect new events by using incremental TF-IDF model and incremental cluster algorithm. Based on analysis of the attributes of events, we propose a method to measure the activity of events, then filter and sort the event according to the activity of events; finally a hot event list can be derived.","Title: 4-Regular maps on the Klein bottle\nYear: 2001\n\nAbstract: In this paper the number of rooted near-4-regular maps on the Klein bottle is investigated and formulae with up to four parameters are given. Also the number of rooted near-4-regular maps with exactly k nonroot-vertex loops on this surface is provided. In particular, explicit formulae for counting (loopless) 4-regular maps on this surface are deduced.","Title: A compact phased array antenna system based on dual-band Butler matrices\nYear: 2013\n\nAbstract: This paper presents a new architecture to minimize the size of conventional phased array antenna. The proposed size reduction of the phased array is achieved by designing the whole system to support dual-band operations. To verify the design concept, a novel dual-band phased array feeding network is designed based on a dual-band 4×4 Butler matrix. By integrating the proposed 4×4 dual-band feeding network with antennas, a total of eight radiation beams can be generated, indicating a size reduction of about 50%. The designed phased array feeding network is operating at 5 and 8GHz. Simulation results show the eight radiation beams as predicted by the design theory, which further validates our design concept.","Title: Information Focus Synthesis Based on Question Answer Chain\nYear: 2009\n\nAbstract: While speech synthesis technologies have come a long way in recent ten years, there is still room for improvement. This paper describes a technique called based on joint information structure, syntax and prosody method, which demonstrates noticeable improvements to existing speech synthesis system. As an important parameter for prosody proceedings in mandarin, information focus prosodic distribution features are typical for hearing natural, speech understanding and information acquisition. Because of the complex mapping relation between information structure, syntax and prosody, we present an efficient method for retrieval information focus to augment a naturalness speech synthesis. We use question answering chain to extract information focus and discover them how to move. Then, we adopt feature classification and prosody predictive modeling to deal with focus's F0 and time period and obtain them features module. Based on the features module, should significantly increase the accuracy and naturalness of speech synthesis. The rest of this paper is organized as follows. Section 2 summarizes the previously proposed theory for information focus extraction, and derives a new method. Experiments are expressed in Section 3. And experimental results are shown in Section 4. Concluding remarks are presented in the final section.","Title: Minimum cycle bases of graphs on surfaces\nYear: 2007\n\nAbstract: In this paper we study the cycle base structures of embedded graphs on surfaces. We first give a sufficient and necessary condition for a set of facial cycles to be contained in a minimum cycle base (or MCB in short) and then set up a 1-1 correspondence between the set of MCBs and the set of collections of nonseparating cycles which are in general positions on surfaces and are of shortest total length. This provides a way to enumerate MCBs in a graph via nonseparating cycles. In particular, some known results such as P.F. Stadler's work on Halin graphs [Minimum cycle bases of Halin graphs, J. Graph Theory 43 (2003) 150-155] and Leydold and Stadler's results on outer-planar graphs [Minimum cycle bases of outerplanar graphs, Electronic J. Combin. 5(16) (1998) 14] are concluded. As applications, the number of MCBs in some types of graphs embedded in lower surfaces (with arbitrarily high genera) is found. Finally, we present an interpolation theorem for the number of one-sided cycles contained in MCB of an embedded graph.","Title: Bisingular maps on the sphere and the projective plane\nYear: 2000\n\nAbstract: A map is bisingular if each edge is either a loop or an isthmus (i.e., on the boundary of the same face). In this paper we study the number of rooted bisingular maps on the plane or projective plane and also we present formulae for such maps with up to three or more parameters: the root valency, the number of isthmus, the number of essential loops, and the number of planar loops.","Title: Lower Bound of the Number of Maximum Genus Embeddings and Genus Embeddings of K12s+7.\nYear: 2011\n\nAbstract: In this paper, we study lower bound of the number of maximum orientable genus embeddings (or MGE in short) for a loopless graph. We show that a connected loopless graph of order n has at least 1/4 gamma M-(G) Pi(upsilon is an element of V(G)) (d(upsilon) - 1)! distinct MGE's, where gamma(M) (G) is the maximum orientable genus of G. Infinitely many examples show that this bound is sharp (i.e., best possible) for some types of graphs. Compared with a lower bound of Stahl (Eur J Combin 13:119-126, 1991) which concerns upper-embeddable graphs (i.e., embedded graphs with at most two facial walks), this result is more general and effective in the case of (sparse) graphs permitting relative small-degree vertices. We also obtain a similar formula for maximum nonorientable genus embeddings for general graphs. If we apply our orientable results to the current graph G (s) of K (12s+7), then G (s) has at least 2(3s) distinct MGE's.This implies that K (12s+7) has at least (22) (s) nonisomorphic cyclic oriented triangular embeddings for sufficient large s.","Title: The crossing number of the circular graph C(2m + 2, m)\nYear: 2005\n\nAbstract: The circular graph C(n,m) is such a graph that whose vertex set is ⌈v0,v1,v2,...,vn-1⌉ and edge set is ⌈vivi+1,vivi+m|i=0,1,..., n-1⌉, where m,n are natural numbers, addition is modulo n, and 2≤m≤⌊n/2⌋. This paper shows the crossing number of the circular graph C(2m+2,m)(m≥3) is m+1. © 2005 Elsevier B.V. All rights reserved.","Title: Counting 2-Connected 4-Regular Maps on the Projective Plane.\nYear: 2014\n\nAbstract: In this paper the number of rooted (near-) 4-regular maps on the projective plane are investigated with respect to the root-valency, the number of edges, the number of inner faces, the number of nonroot-vertex-loops, the number of nonroot-vertex-blocks. As special cases, formulae for several types of rooted 4-regular maps such as 2-connected 4-regular projective planar maps, rooted 2-connected (connected) 4-regular projective planar maps without loops are also presented. Several known results on the number of 4-regular maps on the projective plane are also concluded. Finally, by use of Darboux's method, very nice asymptotic formulae for the numbers of those types of maps are given.","Title: A tunable directional coupler with a wide tuning range of coupling ratios\nYear: 2014\n\nAbstract: A tunable microwave 90-degree directional coupler with a wide tuning range of coupling ratios is introduced in this paper. The architecture of this device is designed based on a fully symmetrical structure. Two varactor diodes loaded to the side of the device are used as the tuning elements. With different biasing voltage, the output power ratio between the two output ports (Port 2 and Port 3) can be easily tuned. During the tuning, very good isolation and low return loss are always kept. In the theoretical discussion, the general design equations are presented. Also, a sample circuit working at 1 GHz was made and tested to verify the design theory. The measurement results of the prototype show a good agreement with the design theory.","Title: Reconfigurable microwave couplers with dynamic performance control\nYear: 2014\n\nAbstract: Two kinds of reconfigurable microwave couplers are presented in this paper. The first one is a 90-degree branch-line coupler with a wide range of tunable coupling ratios. Especially, when its coupling ratio is tuned to be 1, this coupler becomes a crossover. The second one possesses a reconfigurable performance between a rat-race coupler and a 90-degree coupler. Both of the devices have a symmetrical structure, and varactors are loaded to the couplers as the tuning elements. By applying suitable control voltages, the reconfigurable performance is realized. Closed-form equations are derived to theoretically analyze the proposed devices. To further verify the design theory, both structures are simulated. Moreover, the first coupler is fabricated and characterized. Good performance is achieved in both simulation and measurement results.","Title: Finding a shortest cycle in a subspace of the cycle space of a graph\nYear: 2015\n\nAbstract: Thomassen's 3-path-condition shows that it is relatively easy for one to find a shortest cycle in a collection of cycles beyond a subspace of the cycle space of a connected graph and the real challenge is to find a shortest cycle contained in a given subspace of the cycle space of a graph. In this article we investigate the shorter cycle structures in a given subspace of a graph and find a set of cycles in a given graph containing much information about short cycles. We show that for a large range of subspaces of a graph satisfying a \\\"parity condition\\\", there exists a polynomial time algorithm to find a shortest cycle in these subspaces. This makes a unified treatment of several famous algorithms. Finally we provide lower bounds of some types of short cycles in embedded graphs.","Title: A note on graph proper total colorings with many distinguishing constraints.\nYear: 2016\n\nAbstract: •Graph coloring theory has a wide range of applications in many scientific fields. As an application, graph distinguishing colorings may be connected with the frequency assignment problem in wireless communication. The vertices (nodes) of graphs (networks) represent transmitters, the set C[u,f] of colors assigned to a vertex u and the edges (links) incident to u under a total coloring f indicates the frequencies usable. One constrain C[u,f]≠C[v,f] ensures the corresponding two stations u, v can operate on a wide range of frequencies without the danger of interfering with each other. We propose new total colorings having more constraints for researching deeply the frequency assignment problem. Under a proper total coloring f of a simple graph G, f(u) and f(uv) are the color assigned to a vertex u and the color assigned to an edge uv, respectively. We use C(f,u) to denote the set of colors assigned to the edges incident to u, C〈f,u〉 the union of f(u) and the set of colors assigned to the neighbors of u, so we have other two color sets C[f,u]=C(f,u)∪{f(u)}, and C2[f,u]=C(f,u)∪C〈f,u〉. We say f an adjacent vertex distinguishing total coloring (AVDTC) of G if one constraint C[f,u]≠C[f,v] holds for each edge uv of G, and the minimum number of k colors required for which G admits an AVDTC is denoted as χas″(G), which is related with a conjecture: χas″(G)≤Δ(G)+3, where Δ(G) is the maximum degree. We call f a 4-adjacent vertex distinguishing total coloring (4-AVDTC) of G if four distinguishing constraints C(f,x)≠C(f,y), C〈f,x〉≠C〈f,y〉, C[f,x]≠C[f,y] and C2[f,x]≠C2[f,y] hold simultaneously true for every edge uv of G, and the least number of k colors required for which G admits a k-4-AVDTC is denoted by χ4as″(G). We conjecture χ4as″(G)≤Δ(G)+4 if any edge uv of G holds that the set of neighbors of the vertex u differs from the set of neighbors of the vertex v.","Title: Finding Shorter Cycles in a Weighted Graph.\nYear: 2016\n\nAbstract: In this paper we investigate the structures of short cycles in a weighted graph. By Thomassen’s \\(3\\)-path-condition theory (Thomassen in J Comb Theory Ser 48:155–177, 1990), it is easy to find a shortest cycle in a collection of cycles beyond a subspace of the cycle space of a graph. What is more difficult for one to do is to find a shortest cycle within a subspace of the cycle space in polynomial time. By using the Dijkstra’s algorithm (Dijkstra in Numer Math 1:55–61, 1959) we find a collection \\(\\mathcal {C}\\) of cycles containing many types of short cycles within a given subspace of the cycle space of a graph and this implies a polynomial time algorithm (called extended fundamental cycle algorithm) to locate all the possible shortest cycles in a weighted graph. In the case of unweighted graphs, the algorithm may also find every shortest even cycle in a graph, this greatly improved a result of Grötschel and Pulleyblank (Oper Res Lett 1:23–27, 1981/82), Monien (Computing 31:355–369, 1983), Yuster and Zwick (SIAM J Discrete Math 10:209–222, 1997). In fact, our algorithm shows that there are at most \\(O(n^4)\\) many such short cycles in an unweighted graph of order \\(n\\). Further more, our fundamental cycle method may find a minimum cycle base (or simply MCB as some scholars named) in the cycle space of a graph. Since the structure of MCB’s is unique (Ren and Deng in Discrete Math 307:2654–2660, 2007), this shows that, in the sense, cycles in a MCB are nearly-fundamental (i.e., each element in a MCB is a sum of at most two fundamental cycles). This provides a new way to study MCB.","Title: Workspace Calculating And Kinematic Modelling Of A Flexible Continuum Manipulator Constructed By Steel-Wires\nYear: 2015\n\nAbstract: Purpose - The purpose of this paper is to present a new method to establish a kinematic model for a continuum manipulator, whose end can be controlled to move in a three-dimensional workspace. A continuum manipulator has significant advantages over traditional, rigid manipulators in many applications because of its ability to conform to the environment. Moreover, because of its excellent flexibility, light weight, low energy consumption, low production cost, it has a number of potential applications in areas of earthquake relief, agricultural harvesting, medical facilities and space exploration.Design/methodology/approach - This paper uses basic theory of material mechanics to deduct motion equations of the manipulator. Unlike other published papers, the manipulator is not based on segments tactics, but regarded as an integrated flexible system, which simplifies its kinematics modelling and motion controlling. The workspace of the manipulator is analysed by theoretical deducing and simulation modelling. For verification of the presented theory, simulation based on ADAMS software was implemented, while a prototype of the manipulator was developed. Both the software simulation and prototype experiment show that the theoretical analysis in this paper is reasonable. The manipulator can move accurately along the desired trajectories.Findings - This paper developed a novel and fully continuous manipulator driven by steel wires. A kinematic model of the manipulator was established. The physical manipulator developed for verifying the kinematic model can effectively track the prescribed trajectory. The presented kinematic model agrees with not only the simulation but also with the experiment.Research limitations/implications - The manipulator presented in this paper is constructed by steel wires. It possesses the advantages of structural continuity, high flexibility and low production cost. It can be extensively used in many fields, such as search and rescue robotic systems. The limitation of this research is that the dynamic model of the manipulator is not yet clear, which is one of the directions for future research.Practical implications - The manipulator breaks through the limitation of the joint-type or flexible-link-type manipulator, which can also be extensively used in many fields such as search and rescue robotic systems.Social implications - The manipulator developed in this paper, currently, is a prototype under the project of \"Automatic Picking Manipulator Research\". It possesses a good market value.Originality/value - The value of this research is that the manipulator breaks through the limitation of the joint-type or flexible-link-type manipulator and establishes the kinematic model for a fully continuous manipulator by a simple strategy. This is the first study that uses such a strategy for establishing the motion equations of a monolithic continuum manipulator.","Title: L(2, 1)-labeling of a circular graph.\nYear: 2015\n\nAbstract: In this paper the A-number of the circular graph C(km,m) is shown at most 9 where m >= 3 and k >= 2, and the lambda-number of the circular graph C(km+s, m) is shown at most 15 where m >= 3, k >= 2 and 1 <= s <= m - 1. In particular, the lambda-numbers of C(2m, m) and C(n, 2) are determined, which are at most 8. All our results indicates that the Griggs and Yeh's conjecture holds for circular graphs. The conjecture says that for any graph G with maximum degree Delta >= 2, lambda(G) <= Delta(2). Also, we determine A-numbers of C(n, 3), C(n, 4) and C(n, 5) if n equivalent to 0(mod 7).","Title: Information Retrieval Using PU Learning Based Re-ranking\nYear: 2008\n\nAbstract: In this paper, we describe our approach for information retrieval for question answering (IR4QA) on simple Chinese language of NTCIR-7 tasks. Firstly, we use both bi-grams and single Chinese characters as index units and use OKAPI BM25 as retrieval model. Secondly, we re-rank all documents' orders for the first retrieval documents. We focus mostly on the document re-ranking technique. We address probabilistically labeling relevant degree between the first retrieval documents and query topics. In other words, we want to know the probability of a document belongs to relevance/irrelevance class. We employ PU9' positive and unlabeled9' learning to solve this problem, and use Bayesian classifier and EM algorithm in process of computing the probability. Consequently, those relevant documents with high probability are updated rank. Lastly, we use re-ranked retrieved documents to do query expansion. Evaluation at NTCIR-7 shows that our group achieves 0.3862 and 0.3806 MAP based on","Title: Multi-Strategy Question Answering System for NTCIR-7 C-C Task\nYear: 2008\n\nAbstract: In NTCIR-7, ACLIA task focus on more complex questions than factoid ones. To participate in Monolingual Chinese task, we propose a multi-strategy QA system that can handle questions with different types. Basic steps of this system are described as follow: first, pattern-based question type analysis is performed to classify questions of four types, then an Information Retrieval method is utilized to retrieve and re-rank documents that may contain correct answers; after that, we deal retrieved results with different strategies including heuristic rules, pattern matching and web knowledge bases; finally, nuggets are extracted from answer candidates and formed as the results. The evaluation result shows that our system achieves 43.29% average F-score(beta=3). Keywords: NTCIR-7, Multi-Strategy Question Answering, pattern matching, web knowledge","Title: Semantic Role Labeling for Biomedical Corpus Using Maximum Entropy Classifier.\nYear: 2015\n\nAbstract: Semantic role labeling (SRL) is a natural language processing (NLP) task that finds shallow semantic representations from sentences. In this paper, we construct a biomedical proposition bank and train a biomedical semantic role labeling system that can be used to facilitate relation extraction and information retrieval in biomedical domain. Firstly, we construct a proposition bank on the basis of the GENIA TreeBank following the Penn PropBank annotation. Secondly, we use GenPropBank to train a biomedical SRL system, which uses maximum entropy as a classifier. Our experimental results show that a newswire SRL system that achieves an F1 of 85.56 % in the newswire domain can only maintain an F1 of 65.43 % when ported to the biomedical domain. By using our annotated biomedical corpus, we can increase that F1 by 19.2 %.","Title: Odd components of co-trees and graph embeddings.\nYear: 2016\n\nAbstract: In this paper we investigate the relation between odd components of co-trees and graph embeddings. We show that any graph G must share one of the following two conditions: (a)¿for each integer h such that G may be embedded on Sh, the sphere with h handles, there is a spanning tree T in G such that h = 1 2 ( β ( G ) - ω ( T ) ) , where β(G) and ω(T) are, respectively, the Betti number of G and the number of components of G - E ( T ) having odd number of edges; (b)¿¿¿for every spanning tree T of G, there is an orientable embedding of G with exact ω ( T ) + 1 faces. This extends Xuong and Liu's theorem 9,13 to some other (possible) genera. Infinitely many examples show that there are graphs which satisfy (a) but (b). Those make a correction of a result of Archdeacon 2, Theorem¿1.","Title: Adjacent vertex distinguishing total colorings of graphs with four distinguishing constraints.\nYear: 2016\n\nAbstract: Frequency assignment problem was produced in researching mobile communication networks. A proper total coloring of a graph G is a coloring of both edges and vertices of G such that no two adjacent or incident elements receive the same color. As known, the vertex distinguishing total coloring is one of suitable tools for investigating the frequency assignment problem. We introduce a new graph total coloring, called (4)-adjacent vertex distinguishing total coloring ((4)- AVDTC), in tins paper. Our coloring contains the adjacent vertex distinguishing total coloring. The minimum number of colors required for every (4)-AVDTC of G is called the (4)-AVDTC chromatic number of G. We will show that using at most Delta(G) + 4 colors can do at least 4 different adjacent vertex distinguishing actions to some communication networks G. The exact (4)-AVDTC chromatic: numbers of several classes of graphs are determined here and a problem is presented.","Title: Study on the English Corresponding Unit of Chinese Clause\nYear: 2016\n\nAbstract: This paper annotates the English corresponding units of Chinese clauses in Chinese-English translation and statistically analyzes them. Firstly, based on Chinese clause segmentation, we segment English target text into corresponding units (clause) to get a Chinese-to-English clause-aligned parallel corpus. Then, we annotate the grammatical properties of the English corresponding clauses in the corpus. Finally, we find the distribution characteristics of grammatical properties of English corresponding clauses by statistically analyzing the annotated corpus: there are more clauses (1631,74.41%) than sentences (561,25.59%); there are more major clauses (1719,78.42%) than subordinate clauses (473,21.58%); there are more adverbial clauses (392,82.88%) than attributive clauses (81,17.12%) and more non-defining clauses (358,75.69%) than restrictive relative clauses (115,24.31%) in subordinate clauses; and there are more simple clauses (1142,52.1%) than coordinate clauses (1050,47.9%).","Title: Sports News Generation from Live Webcast Scripts Based on Rules and Templates\nYear: 2016\n\nAbstract: With the dramatic increase of the live webcast scripts about sports, it is an urgent demand to write and publish a sports news article immediately after a sports game. However, so far, the sports news articles are usually written by human experts or journalists, and the manual writing of sports news is time-consuming and inefficient. This paper describes our system on the sports news generation from live webcast scripts task. On one hand, our system extracts the important events occurring in the time period from the live webcast scripts according to the rules, and on the other hand, our system generates a brief summary from the live webcast scripts about the football matches. According to the characteristic of live webcast scripts, we adopt an approach to sentence extraction and template generation from live webcast scripts. The evaluation results show that our system is feasible in sports news generation from live webcast scripts.","Title: The Number of 1-Factors and Edge-Colorings of Mobius Ladder Graphs and Triangular Embeddings of K12m+7.\nYear: 2016\n\nAbstract: In this paper we study the number of 1-factors and edge-colorings of the Mobius ladder graphs. We find exact formulae for such numbers and show that there are exponentially many 1-factors and edge-colorings in such graphs. As applications, we show that every \"men-made\" triangular embedding for K12m+7 by the current graphs by these of Youngs and Ringel permits exponentially many \"Grunbaum colorings\" (i.e.,3-edge-colored triangulations in such a way that each triangle receives three distinct colors.)","Title: The orientable genus of the generalized Petersen graph P(km, m).\nYear: 2017\n\nAbstract: In the paper we show that the orientable genus of the generalized Petersen graph P(km, m) is at least km/4-m/2-km/4m-4+1 if m >= 4 and k > 3. We determine the orientable genera of P(3m, m), P(4k, 4), P(4m, m) if m >= 4, P(6m, m) if m equivalent to 0 (mod 2) and m >= 6, and so on.","Title: A new formula for the decycling number of regular graphs.\nYear: 2017\n\nAbstract: The decycling number ∇(G) of a graph G is the smallest number of vertices which can be removed from G so that the resultant graph contains no cycle. A decycling set containing exactly ∇(G) vertices of G is called a ∇-set. For any decycling set S of a k-regular graph G, we show that |S|=β(G)+m(S)k−1, where β(G) is the cycle rank of G, m(S)=c+|E(S)|−1 is the margin number of S, c and |E(S)| are, respectively, the number of components of G−S and the number of edges in G[S]. In particular, for any ∇-set S of a 3-regular graph G, we prove that m(S)=ξ(G), where ξ(G) is the Betti deficiency of G. This implies that the decycling number of a 3-regular graph G is β(G)+ξ(G)2. Hence ∇(G)=⌈β(G)2⌉ for a 3-regular upper-embeddable graph G, which concludes the results in [Gao et al., 2015, Wei and Li, 2013] and solves two open problems posed by Bau and Beineke (2002). Considering an algorithm by Furst et al., (1988), there exists a polynomial time algorithm to compute Z(G), the cardinality of a maximum nonseparating independent set in a 3-regular graph G, which solves an open problem raised by Speckenmeyer (1988). As for a 4-regular graph G, we show that for any ∇-set S of G, there exists a spanning tree T of G such that the elements of S are simply the leaves of T with at most two exceptions providing ∇(G)=⌈β(G)3⌉. On the other hand, if G is a loopless graph on n vertices with maximum degree at most 4, then ∇(G)≤n+12,if G is 4-regular,n2,otherwise.The above two upper bounds are tight, and this makes an extension of a result due to Punnim (2006).","Title: Recognizing Textual Entailment Using Inference Phenomenon\nYear: 2017\n\nAbstract: Inference phenomena refer to inference relations in local fragments between two texts. Current research on inference phenomenon focuses on the construction of data annotation, whereas there are few research on how to identify those inference phenomena in texts, which will contributes to improving the performance of recognizing textual entailment. This paper proposes an approach, which uses inference phenomena to recognize entailment in texts. In the approach, the task of recognizing textual entailment is formalized as two problems, that is, inference phenomenon identification and entailment judgment, then a joint model is employed to combine such two related subtasks, which is helpful to avoid error propagation. Experimental results show that the approach performs efficiently for identifying inference phenomena and recognizing entailment at the same time.","Title: Building A Parallel Corpus With Bilingual Discourse Alignment\nYear: 2017\n\nAbstract: This paper describes a discourse resource, namely a Chinese-English parallel corpus, based on the idea of bilingual discourse alignment. We introduce a bilingual collaborative annotation approach, which annotates English discourse units based on Chinese ones, and annotates Chinese discourse structure based on English ones subsequently. Such approach can ensure full discourse structure alignment between parallel texts, and reduce cost for annotating texts of two languages as well. Annotation Evaluation of the parallel corpus justifies the appropriateness of the discourse alignment framework to parallel texts.","Title: Extractive Single Document Summarization via Multi-feature Combination and Sentence Compression.\nYear: 2017\n\nAbstract: In this paper, we attempt to extract and generate the short summary for the news article with the length limit of 60 Chinese characters. Firstly, we preprocess the news article by segmenting sentences and words, and then extract four kinds of central words to form the keyword dictionary based on parsing tree. After that, the four kinds of features, i.e. the sentence weight, the sentence similarity, the sentence position and the length of sentence, will be employed to measure the significance of each sentence. Finally, we extract two sentences in the descending order of significance score and compress them to get the summary for each news article. This approach can analyze the grammatical elements from original sentences in order to generate compression rules and trim syntactic elements according to their parsing trees. The evaluation results show that our system is efficient in Chinese news summarization.","Title: Answer Ranking Based on Language Phenomenon Recognition.\nYear: 2018\n\nAbstract: Answer Ranking is one of the core tasks in Question Answering, which greatly depends on the performance of answer ranking. This paper introduces an approach of answer ranking based on language phenomenon identification, that is, identifying language phenomena between a question and its answer sentence candidates, then computing entailment confidence score between the question and each candidate. Finally, an answer ranking is made according to such scores. This paper also introduces a joint model for both language phenomenon identification and entailment recognition task, in order to avoid error propagation to some extent, and make the two tasks learn to each other for a better overall performance as well. Experimental results show that the joint learning of language phenomenon identification and entailment recognition is an effective way for answer ranking.","Title: A Comparative Study on the Coordinate Relation of Chinese Official Documents in Mainland, Hong Kong and Macau.\nYear: 2018\n\nAbstract: This paper investigates the coordinate relation in Mainland Chinese, Hong Kong Chinese and Macau Chinese, including explicit relations, implicit relations and their parallel items. In order to conduct the comparative study, a corpus including official documents of Mainland China, Hong Kong and Macau has been built. The study shows that the frequency of the explicit coordinate relation appearing in Hong Kong (53.5%) and Macao texts (23.1%) is much higher than that in Mainland China texts (1.5%), and the explicit coordinate relation occurs most frequently in Hong Kong texts. The study also shows that the connective types in Hong Kong (59 types) and Macao texts (21 types) are much more than that in Mainland China texts (11 types). Such differences are probably derived from the English influence on Hong Kong and Macau Chinese, according to the comparative results of the coordinate relation in English and Chinese texts of Hong Kong and Macau.","Title: New formulae for the bipartite vertex frustration and decycling number of graphs.\nYear: 2019\n\nAbstract: Let ∇2(G), φ(G) and ∇(G) denote the bipartite vertex frustration, bipartite edge frustration and decycling number of a graph G, respectively. In this paper, we show that ∇2(G)=|V(G)|−max {α(G−E(B)):B is a spanning bipartite subgraph of G}, which provides a new method to estimate the bipartite vertex frustration in terms of bipartite edge frustration for graphs. Using the formula above and some known results on the bipartite edge frustration, we derive several new results on the bipartite vertex frustration, including some that are equalities. Further, we study the bipartite vertex frustration of five classes of composite graphs. Finally, we present a formula for the decycling number: ∇(G)=|V(G)|−max{α(G−E(F)):FisaspanningforstofG}. Based on this result, we determine the decycling numbers of many certain graphs. In addition, this formula gives a new way for dealing with the decycling number problem of dense graphs.","Title: Study on stretch-retractable single-section continuum manipulator.\nYear: 2019\n\nAbstract: This paper proposes a stretch-retractable single-section (SRSS) continuum manipulator. Its backbone is composed by a series of springs. Thus, this continuum manipulator owns feature of a large-scale stretch-retractable ability. With such a feature, different from traditional single-section continuum manipulator which distal end moves in a curved surface, the presented manipulator's distal end has a solid work space. The kinematic model including the variable parameter of backbone length was established, and the stretch-retractable workspace was analyzed, with which the driving strategy was proposed. The prototype was made out based on the concept of the large-scale stretch-retractable backbone. The driving patterns with single parameter input and the driving patterns with multi parameter inputs were carried out. The tests verified the presented SRSS continuum manipulator.","Title: Neural Networks For Bacterial Named Entity Recognition\nYear: 2018\n\nAbstract: Bacterial named entity recognition is a challenging task in biomedical field. The task is typically modeled as a sequence labeling problem, and existing work mainly adopts discrete models such as CRF (Conditional Random Fields), requiring a large amount of hand-designed features with domain experience. To address this issue, this paper explores a neural network model for the task. We empirically study the effect of word embeddings and character embeddings on the task by extending a CRF baseline using neural networks. Results show the proposed neural network model achieves competitive performance, outperforming the current best discrete model. Meanwhile, the performance can be further improved by integrating neural and discrete features.","Title: Decycling Number of a class of 4-regular graphs.\nYear: 2018\n\nAbstract: Let del(G) denote the minimum number of vertices of G whose removal results in an acyclic graph (i.e., a forest). Such a number del(G) is called the decycling number of graph G. In this paper, we discuss the decycling number of a class of 4-regular graphs.","Title: The decycling number and maximum genus of cubic graphs.\nYear: 2018\n\nAbstract: Let delta(G) and M(G) denote the minimum size of a decycling set and maximum genus of a graph G, respectively. For a connected cubic graph G of order n, it is shown that delta(G)+M(G)=n 2+1. Applying the formula, we obtain some new results on the decycling number and maximum genus of cubic graphs. Furthermore, it is shown that the number of vertices of a decycling set S in a k-regular graph G is |S|=1k-1{(G)+c+mS-1}, where c and are the number of components of G-S and the number of edges in G[S], respectively. Therefore, S is minimum if and only if c+<-1 is minimum. As an application, this leads to a lower bound delta(G)remvoe(G)k-1 for delta(G) of a k-regular graph G. In many cases this bound may be sharp.","Title: Stretched Backboneless Continuum Manipulator Driven By Cannula Tendons\nYear: 2018\n\nAbstract: Purpose - The purpose of this paper is to present a stretched backboneless continuum manipulator, which aims to provide sufficient inner room for potential transportation of objects or fixture of necessary devices, and to reduce the number of motors for reduction of the weight of the system.Design/methodology/approach -A mathematical model of the presented manipulator is established in this paper. To verify the presented theory, the position of the free end was recorded by a high-resolution digital camera in experiment. According to the comparison of experimental values and theoretical values, the error is less than 2.5 per cent. It shows that the mathematical model and theoretical analysis are reasonable; the presented continuum manipulator can reach to desired postures and positions.Findings - This paper presents a new stretched backboneless continuum manipulator supported and driven by cannula tendons. The cannula tendons are composed of rubber tubes and glass fibers. The upper section and the lower section of the presented manipulator are driven by same motors. For steering the manipulator, switched driving strategy is developed based on the presented kinematics model. The presented manipulator possesses six degrees of freedom (DOFs) and has good performance in dealing with complex working environment. The experiment verifies the presented driving strategy.Research limitations/implications - The presented backboneless continuum manipulator has only two sections and is supported by cannula tendons. Extending this structure to further more sections is a challenge and is left for future research.Originality/value - The value of this study is to propose a stretched backboneless continuum manipulator, which can provide inner room as large as possible for potential usage and halve the number of motors, for which a switched driving strategy is put forward. As a result, the weight and complexity of the manipulator are decreased. The presented manipulator is able to move in potential complex environments and approach its objects in different postures in virtue of its high flexibility and its six DOFs.","Title: Context-augmented convolutional neural networks for twitter sarcasm detection.\nYear: 2018\n\nAbstract: Sarcasm detection on twitter has received increasing research in recent years. However, existing work has two limitations. First, existing work mainly uses discrete models, requiring a large number of manual features, which can be expensive to obtain. Second, most existing work focuses on feature engineering according to the tweet itself, and does not utilize contextual information regarding the target tweet. However, contextual information (e.g. a conversation or the history tweets of the target tweet author) may be available for the target tweet. To address the above two issues, we explore the neural network models for twitter sarcasm detection. Based on convolutional neural network, we propose two different context-augmented neural models for this task. Results on the dataset show that neural models can achieve better performance compared to state-of-the-art discrete models. Meanwhile, the proposed context-augmented neural models can effectively decode sarcastic clues from contextual information, and give a relative improvement in the detection performance.","Title: Lower bound on the number of Hamiltonian cycles of generalized Petersen graphs\nYear: 2020\n\nAbstract: In this paper, we investigate the number of Hamiltonian cycles of a generalized Petersen graph P(N, k) and prove that psi(P(N, 3) >= N center dot alpha(N) where psi(P(N, 3)) is the number of Hamiltonian cycles of P(N, 3) and alpha(N) satisfies that for any epsilon > 0, there exists a positive integer M such that when N > M, ((1-epsilon)(1-r(3))/6r(3)+5r(2)+3)(1/r)(N+2) < alpha N < ((1+epsilon)(1-r(3))/6r(3)+5r(2)+3)(1/r)(N+2), where 1/r = max {vertical bar 1/r (j)vertical bar j = 1, 2,..., 6} and each r(j) is a root of equation x(6) + x(5) + x(3) - 1 = 0, r approximate to 0.782. This shows that psi(P(N, 3) is exponential in N and also deduces that the number of 1-factors of P(N, 3) is exponential in N.","Title: A Note on Decycling Number, Vertex Partition and AVD-Total Coloring in Graphs.\nYear: 2018\n\nAbstract: This note provides a new perspective, i.e., graph embeddings on the decycling number \\(\\nabla (G)\\) (Beineke and Vandell in J Graph Theory 25:59–77, 1997) of a graph G. For this point, it is shown that \\(\\nabla (G)=\\gamma _M(G)+\\xi (G)\\) for any cubic graph G and \\(|S|=\\frac{\\beta (G)+m(S)}{k-1}\\) for any decycling set S of a k-regular graph G, where \\(\\gamma _M(G)\\), \\(\\xi (G)\\), \\(\\beta (G)\\) and \\(m(S)=c(G-S)+|E(S)|-1\\) (\\(c(G-S)\\) is the number of components of \\(G-S\\) and |E(S)| is the number of edges in a subgraph G[S]) are, respectively, the maximum genus, the Betti deficiency (Xuong in J Combin Theory Ser B 26:217–225, 1979), the cycle rank (Harary in Graph theory, Academic Press, New York, 1967) and the margin number of G. Meanwhile, we further confirm that (1) a cubic graph G (\\(G\\ne K_4\\)) has a vertex partition \\((V_1, V_2)\\) such that \\(V_1\\) is an independent set and \\(V_2\\) induces a forest and (2) a k-regular graph G with \\(\\nabla (G)=\\frac{\\beta (G)+m(S)}{k-1}\\) (\\(m(S)\\le 2\\)) has a vertex partition \\((S,G-S)\\) such that G[S] contains at most two edges and \\(G-S\\) induces a forest, where S is the smallest decycling set of G. Resorting to the above vertex partitions, we get the adjacent vertex distinguishing (AVD) total chromatic numbers of some families of graphs, and these results verify Zhang’s conjecture (Zhang in Sci China Ser A 48:289–299, 2005) that every graph with maximum degree \\(\\Delta \\) has an AVD-total \\((\\Delta +3)\\)-coloring.","Title: Bounds for Judicious Balanced Bipartitions of Graphs.\nYear: 2018\n\nAbstract: A bipartition of the vertex set of a graph is called balanced if the sizes of the sets in the bipartition differ by at most one. Bollob\\(\\acute{a}\\)s and Scott proved that every regular graph with m edges admits a balanced bipartition \\(V_{1}\\), \\(V_{2}\\) of V(G) such that \\(\\max \\{e(V_{1}), e(V_{2}) \\}< \\frac{m}{4}\\). Only allowing \\(\\varDelta (G)-\\delta (G)\\) =1 and 2, Yan and Xu, and Hu, He and Hao, respectively showed that a graph G with n vertices and m edges has a balanced bipartition \\(V_{1}\\), \\(V_{2}\\) of V(G) such that \\(\\max \\{e(V_{1}), e(V_{2}) \\}\\le \\frac{m}{4}+O(n)\\). In this paper, we give an upper bound for balanced bipartition of graphs G with \\(\\varDelta (G)-\\delta (G)=t-1\\), \\(t\\ge 2\\) is an integer. Our result extends the conclusions above.","Title: Emotion Cause Detection with a Hierarchical Network\nYear: 2021\n\nAbstract: Emotion cause detection plays a key role in many downstream sentiment analysis applications. Research shows that both knowledge from data and experience from linguistics help to improve the detection performance. In this paper, we propose an approach to combine them. We utilize a hierarchical framework to model emotional texts, in which the emotion is independently represented along with each word and clause in a document. We also employ linguistic features to help the model find the emotion cause. Such features by manual work help to describe deep semantic relations between emotions and their causes that are difficult to be cast by representation models. Experimental results show that the combination model helps to detect emotion cause within emotional texts with complex semantic relations.","Title: Distributions of Near-4-Regular Maps on the Sphere and the Projective Plane\nYear: 2021\n\nAbstract: Let U-n and (u) over bar (n) (A(n) and ($) over bar (n)) denote the sets of all rooted near-4-regular maps with n inner faces (n edges) on the sphere and the projective plane, respectively. Let p(m) and (p) over bar (m) be, respectively, the limit probability (as n -> infinity) of the event that the rooted vertex of a map chosen in U-n and (u) over bar (n) (A(n) and ($) over bar (n)) at random is of valency 2m. It is shown that both p(m) and (p) over bar (m) obey the asymptotic pattern characterized by the factor m(1/2): Cm-1/2(2/3)m as m -> infinity, where C is a constant depending on the type of maps, meanwhile each of q(m) and ($) over bar (m) will not satisfy the root-vertex valency distribution pattern posed in Liskovets (J Combin Theory Ser B 75, 116- 133, 1999) (i.e., q(m) = (q) over bar (m) = 0 for every natural number m). In particular, those maps can not satisfy several other classical patterns for n-edged maps.","Title: Mean Color Numbers of Some Graphs\nYear: 2022\n\nAbstract: Let mu(G) denote the mean color number of a graph G. Dong proposed two mean color conjectures. One is that for any graph G and a vertex w in G with d(w) > 1, if H is a graph obtained from G by deleting all but one of the edges which are incident to w, then it(G)> it(H). The other is that for any graph G and a vertex w in G, it(G)>.((G w) U In this paper, we show that the two conjectures hold under the condition that w is a simplicial vertex in G. And when G is a connected (n, m) graph and w is not a cut vertex in G with d(w) = n 1, if rn < + 2) n 4.5 the second conjecture holds too. The two conjectures also hold for some special cases, such as wheels and chordal graphs (Dong in J Combin Theory Ser B 87: 348-365, 2003).","Title: Cascade Residual Capsule Network for Hyperspectral Image Classification\nYear: 2022\n\nAbstract: Theconvolution neural network (CNN) has recently shown the good performance in hyperspectral image (HSI) classification tasks. Many CNN-based methods crop image patches from original HSI as inputs. However, the input HSI cubes usually contain background and many hyperspectral pixels with different land-cover labels. Therefore, the spatial context information on objects of the same category is diverse in HSI cubes, which will weaken the discrimination of spectral-spatial features. In addition, CNN-based methods still face challenges in dealing with the spectral similarity between HSI cubes of spatially adjacent categories, which will limit the classification accuracy. To address the aforementioned issues, we propose a cascade residual capsule network (CRCN) for HSI classification. First, a residual module is designed to learn high-level spectral features of input HSI cubes in the spectral dimension. The residual module is employed to solve the problem of the spectral similarity between HSI cubes of spatially adjacent categories. And then two 3-D convolution layers are exploited to extract high-level spatial-spectral features. Finally, a capsule structure is developed to characterize spatial context orientation representations of objects, which can effectively deal with the diverse spatial context information on objects of the same category in HSI cubes. The capsule module is composed of two 3-D convolution layers and the capsule structure, which is connected to the residual module in series to construct the proposed CRCN. Experimental results on four public HSI datasets demonstrate the superiority of the proposed CRCN over six state-of-the-art models.","Title: Dynamical Analysis of Border Collision Bifurcation in One-Cycle Controlled Single-Inductor Dual-Output Boost DC-DC Converters\nYear: 2022\n\nAbstract: In this paper, the evolution of three types of border collision bifurcations are investigated thoroughly for a high-order single-inductor double-output DC-DC converter with one-cycle control (OCC). Multi-piecewise inductor current with more than one border and cross-coupling effect between different output ports are prominent features of the system, resulting in unexpected period incrementing cascade and transition from periodicity to chaos as a parameter is varied. A high-order nonlinear iterative map model is proposed, which reveals the underlying mechanisms of those complicated nonstandard and unsmooth bifurcations in the multiple-output system. Additionally, theoretical analysis shows that those nonstandard bifurcations arise from the boundary collisions, and more specifically, a fixed point suddenly appears in the borderline between various regions. Besides eigenvalue loci changes abruptly at the bifurcation point, the characteristic of border collision bifurcation is the topology sequence changes. Furthermore, the parameter boundaries are given to provide useful guidance for design. Finally, PSpice circuit experiments are performed to verify the above theoretical and numerical results.","Title: The number of 4-cycles in a graph\nYear: 2022\n\nAbstract: In extremal graph theory studies, it is not yet finished to determine the exact value of ex(n; C-4) in general case. Erdos and Simonovits [10] conjectured that an n-vertex graph G with ex(n; C-4 ) + 1 edges may contain at least root n + o(root n) 4-cycles. In this paper we investigate the number of 4-cycles in a graph. We show that the number of 4-cycles in an n-vertex graph G is at least (epsilon root 4n - 3 )/4 + epsilon(2)/(2n) provided that |E(G)| = n (1 + root 4n - 3 )/4 + epsilon, where epsilon is an arbitrary positive real number. This result is an approach solving to this open problem. Furthermore, we prove that if n is large enough, then there are at least ((4 epsilon - 1)root 4n - 3 + 5)/16 + o(1) 4-cycles in an n-vertex graph with e = (n - 1)(1 + root 4n - 3 )/4 + epsilon edges which has k vertices whose degrees are mutually different, where k >= 3 root 24n +3 root 12n -(12n)(2) - 1/27 and epsilon > 0 is a real number. In addition, we get that a triangle-free graph with n vertices and e = n root n - 1/2 + epsilon edges has at least (2 epsilon(root n - 1 - 2) + 1)/4 + o(1) 4-cycles, where epsilon > 0 is an any real number and n is large enough. This shows that the weak version of Erdos and Simonovits' conjecture [10] holds for such graphs when n is sufficiently large. Finally, we obtain a bipartite version of this result. (C) 2022 Elsevier Inc. All rights reserved.","Title: A Fast Direct Position Determination Algorithm for LFM Signal Based on Spectrum Detection\nYear: 2022\n\nAbstract: For the purpose of simultaneously estimating and locating the linear frequency modulation (LFM) emitter with unknown parameters, an innovative approach, i.e., Fast Direct Position Determination (FDPD), is introduced. The proposed algorithm is based on maximum likelihood estimation (MLE) and spectrum detection. To improve the accuracy and overcome the dramatic complexity of plain maximum likelihood formulation, we further derive the objective function equation of Direct Position Determination (DPD) algorithm and present an enhanced strategy to solve the highly nonlinear optimization problem. By combining the two-step localization method, one-step localization method, and short-time Fourier transform (STFT), our approach realizes jointly estimation of the transmitted signal parameters and emitter localization. Simulation results show that the proposed method is superior compared to the existing DPD, and two-step localization algorithms in terms of localization error and computational complexity, especially for low signal-to-noise ratio (SNR).","Title: The Number of Copies of $$K_{2,t+1}$$ K 2 , t + 1 in a Graph\nYear: 2022\n\nAbstract: It is not yet finished to locate the exact value of ex\n \n \n \n $$(n;K_{2,t+1})$$\n \n in the extremal graph theory. Füredi (J Combin Theory Ser A 75(1):141–144, 1996) proved that the Hyltén-Cavallius’ bound \n \n \n \n $$\\frac{n}{4}\\left( \\sqrt{4tn-4t+1}+1 \\right)$$\n \n is asymptotically best possible for ex\n \n \n \n $$(n;K_{2,t+1})$$\n \n . In this paper we investigate the number of copies of \n \n \n \n $$K_{2,t+1}$$\n \n (\n \n \n \n $$t\\ge 2$$\n \n ) in a graph. We show that an n-vertex graph G contains at least \n \n \n \n $$\\frac{\\epsilon }{t+1}\\sqrt{4tn-4t+1}+\\frac{8t\\epsilon ^2}{(t+1)(n-1)}+\\frac{2\\epsilon ^2}{(t+1)n}$$\n \n copies of \n \n \n \n $$K_{2,t+1}$$\n \n provided that \n \n \n \n $$|E(G)|=\\frac{n}{4}\\left( \\sqrt{4tn-4t+1}+1 \\right) +\\epsilon$$\n \n , where \n \n \n \n $$\\epsilon >0$$\n \n is a real number. Furthermore, we also obtain a formula for the number of copies of \n \n \n \n $$K_{2,t+1}$$\n \n in a graph."],"string":"[\n \"Title: A web knowledge based approach for complex question answering\\nYear: 2011\\n\\nAbstract: Current researches on Question Answering concern more complex questions than factoid ones. Since complex questions are investigated by many researches, how to acquire accurate answers still becomes a core problem for complex QA. In this paper, we propose an approach that estimates the similarity by topic model. After summarizing relevant texts from web knowledge bases, an answer sentence acquisition model based on Probabilistic Latent Semantic Analysis is introduced to seek sentences, in which the topic is similar to those in definition set. Then, an answer ranking model is employed to select both statistically and semantically similar sentences between sentences retrieved and sentences in the relevant text set. Finally, sentences are ranked as answer candidates according to their scores. Experiments show that our approach achieves an increase of 5.19% F-score than the baseline system.\",\n \"Title: Enumeration of 2-connected loopless 4-regular maps on the plane\\nYear: 2002\\n\\nAbstract: In this paper rooted (near-) 4-regular maps on the plane are counted with respect to the root-valency, the number of edges, the number of inner faces, the number of non-root vertex loops, the number of non-root vertex blocks, and the number of multi-edges. As special cases, formulae of several types of rooted 4-regular maps such as 2-connected 4-regular planar maps, rooted 2-connected (connected) 4-regular planar maps without loops are also presented. Several known results on 4-regular maps and trees of Tutte are also concluded. Finally, asymptotic formulae for the numbers of those types of maps are given.\",\n \"Title: Enumerative Properties of Rooted Circuit Maps\\nYear: 2010\\n\\nAbstract: In 1966, Barnette introduced a set of graphs, called circuit graphs, which are obtained from 3-connected planar graphs by deleting a vertex. Circuit graphs and 3-connected planar graphs share many interesting properties which are not satisfied by general 2-connected planar graphs. Circuit graphs have nice closure properties which make them easier to deal with than 3-connected planar graphs for studying some graph-theoretic properties. In this paper, we study some enumerative properties of circuit graphs. For enumeration purpose, we define rooted circuit maps and compare the number of rooted circuit maps with those of rooted 2-connected planar maps and rooted 3-connected planar maps.\",\n \"Title: Finding Answers to Definition Questions Using Web Knowledge Bases.\\nYear: 2009\\n\\nAbstract: Current researches on Question Answering concern more complex questions than factoid ones. Since definition questions are investigated by many researches, how to acquire accurate answers still becomes a core problem for definition QA. Although some systems use web knowledge bases to improve answer acquisition, we propose an approach that leverage them in an effective way. After summarizing definitions from web knowledge bases and merge them to a definition set, a two-stage retrieval model based on Probabilistic Latent Semantic Analysis is produced to seek documents and sentences in which the topic is similar to those in definition set. Then, an answer ranking model is employed to select both statistically and semantically similar sentences between sentences retrieved and sentences in definition set. Finally, sentences are ranked as answer candidates according to their scores. Experiments indicate following conclusions: 1) specific summarization technologies improves definition QA systems to a better performance; 2) topic based models can be more helpful than centroid-based models for definition QA systems in solving synonym and data sparse problems; 3) shallow semantic analysis is effective to find discriminative characteristics of definitions automatically. © 2009 by Han Ren, Donghong Ji, Jing Wan, and Chong Teng.\",\n \"Title: Maximum Genus Embeddings and Genus Embeddings on Orientable Surfaces.\\nYear: 2013\\n\\nAbstract: In this paper, the estimations of maximum genus orientable embeddings of graphs are studied, and an exponential lower bound for such numbers are found. Moreover, such two extremal embeddings (i.e., the maximum genus orientable embedding of the current graph and the minimum genus orientable embedding of the complete graph) are sometimes closely related with each other. As applications, we estimate the number of the minimum genus orientable embeddings for complete graph, by estimating the number of maximum genus orientable embedings for current graph.\",\n \"Title: Exponentially Many Monochromatic n-Matchings in K 3n-1\\nYear: 2012\\n\\nAbstract: Erdös et al and Gerencsér et al had shown that in any 2-edge-coloring of K 3n-1, there is a n-matching containing edges with the same color(we call such matching monochromatic matching). In this paper we show that for any 2-edge-coloring of K 3n-1 there exists a monochromatic subgraph H of K 3n-1 which contains exponentially many monochromatic n-matchings.\",\n \"Title: Automatic Chinese Catchword Extraction Based on Time Series Analysis.\\nYear: 2008\\n\\nAbstract: Catchwords refer to those popular words or phrases in a time period. In this paper, we propose a novel approach for automatic extraction of Chinese catchwords. By analyzing features of catchwords, we define three aspects to describe Popular Degree of catchwords. Then we use curve fitting in Time Series Analysis to build Popular Degree Curves of the extracted terms. Finally we give a formula that can calculate Popular Degree values of catchwords and get a ranking list of catchword candidates. Experiments show that the method is effective.\",\n \"Title: Lower bound on the number of the maximum genus embedding of Kn, n.\\nYear: 2013\\n\\nAbstract: In this paper, we provide a method to obtain the lower bound on the number of the distinct maximum genus embedding of the complete bipartite graph K-n,K-n (n is an odd number), which, in some sense, improves the results of S. Stahl and H. Ren.\",\n \"Title: The number of loopless 4-regular maps on the projective plane\\nYear: 2002\\n\\nAbstract: In this paper rooted loopless (near) 4-regular maps on surfaces such as the sphere and the projective plane are counted and exact formulae with up to three or four parameters for such maps are given. Several classical results on regular maps and one-faced maps are deduced.\",\n \"Title: Parsing Syntactic and Semantic Dependencies for Multiple Languages with A Pipeline Approach.\\nYear: 2009\\n\\nAbstract: This paper describes a pipelined approach for CoNLL-09 shared task on joint learning of syntactic and semantic dependencies. In the system, we handle syntactic dependency parsing with a transition-based approach and utilize MaltParser as the base model. For SRL, we utilize a Maximum Entropy model to identify predicate senses and classify arguments. Experimental results show that the average performance of our system for all languages achieves 67.81% of macro F1 Score, 78.01% of syntactic accuracy, 56.69% of semantic labeled F1, 71.66% of macro precision and 64.66% of micro recall.\",\n \"Title: Vertex Splitting and Upper Embeddable Graphs\\nYear: 2012\\n\\nAbstract: The weak minor G of a graph G is the graph obtained from G by a sequence of edge-contraction operations on G. A weak-minor-closed family of upper embeddable graphs is a set G of upper embeddable graphs that for each graph G in G, every weak minor of G is also in G. Up to now, there are few results providing the necessary and sufficient conditions for characterizing upper embeddability of graphs. In this paper, we studied the relation between the vertex splitting operation and the upper embeddability of graphs; provided not only a necessary and sufficient condition for characterizing upper embeddability of graphs, but also a way to construct weak-minor-closed family of upper embeddable graphs from the bouquet of circles; extended a result in J: Graph Theory obtained by L. Nebesk{\\\\P}y. In addition, the algorithm complex of determining the upper embeddability of a graph can be reduced much by the results obtained in this paper.\",\n \"Title: Enumerating near-4-regular maps on the sphere and the torus\\nYear: 2001\\n\\nAbstract: In this paper rooted near-4-regular maps on the plane and the torus are counted with formulae with respect to four parameters: the root valency, the number of edges, the inner faces, and nonroot-vertex loops. In particular, the number of rooted near-4-regular maps on those surfaces with exactly k nonroot-vertex loops is investigated.\",\n \"Title: Homeomorphically irreducible spanning trees in locally connected graphs\\nYear: 2012\\n\\nAbstract: A spanning tree T of a graph G is called a homeomorphically irreducible spanning tree (HIST) if T does not contain vertices of degree 2. A graph G is called locally connected if, for every vertex v ∈ V(G), the subgraph induced by the neighbourhood of v is connected. In this paper, we prove that every connected and locally connected graph with more than 3 vertices contains a HIST. Consequently, we confirm the following conjecture due to Archdeacon: every graph that triangulates some surface has a HIST, which was proposed as a question by Albertson, Berman, Hutchinson and Thomassen.\",\n \"Title: Generating cycle spaces for graphs on surfaces with small genera\\nYear: 2004\\n\\nAbstract: In this paper we investigate cycle base structures of a 2-(edge)-connected graph on surfaces with small genera and show that short cycles do generate the cycle spaces in the case of \\\"small face-embeddings\\\". Examples show that the conditions in our main results are best possible. As applications we find the exact formulae for the minimum lengths of cycle bases of some types of graphs which conclude several known results. Finally, we generalize those results for graphs embedded on general orientable surfaces.\",\n \"Title: Semi-automatic hot event detection\\nYear: 2006\\n\\nAbstract: In this paper, we propose a method to detect hot event automatically. We use all the web pages from Jan 1st 2005 to Dec 31st 2005, and detect new events by using incremental TF-IDF model and incremental cluster algorithm. Based on analysis of the attributes of events, we propose a method to measure the activity of events, then filter and sort the event according to the activity of events; finally a hot event list can be derived.\",\n \"Title: 4-Regular maps on the Klein bottle\\nYear: 2001\\n\\nAbstract: In this paper the number of rooted near-4-regular maps on the Klein bottle is investigated and formulae with up to four parameters are given. Also the number of rooted near-4-regular maps with exactly k nonroot-vertex loops on this surface is provided. In particular, explicit formulae for counting (loopless) 4-regular maps on this surface are deduced.\",\n \"Title: A compact phased array antenna system based on dual-band Butler matrices\\nYear: 2013\\n\\nAbstract: This paper presents a new architecture to minimize the size of conventional phased array antenna. The proposed size reduction of the phased array is achieved by designing the whole system to support dual-band operations. To verify the design concept, a novel dual-band phased array feeding network is designed based on a dual-band 4×4 Butler matrix. By integrating the proposed 4×4 dual-band feeding network with antennas, a total of eight radiation beams can be generated, indicating a size reduction of about 50%. The designed phased array feeding network is operating at 5 and 8GHz. Simulation results show the eight radiation beams as predicted by the design theory, which further validates our design concept.\",\n \"Title: Information Focus Synthesis Based on Question Answer Chain\\nYear: 2009\\n\\nAbstract: While speech synthesis technologies have come a long way in recent ten years, there is still room for improvement. This paper describes a technique called based on joint information structure, syntax and prosody method, which demonstrates noticeable improvements to existing speech synthesis system. As an important parameter for prosody proceedings in mandarin, information focus prosodic distribution features are typical for hearing natural, speech understanding and information acquisition. Because of the complex mapping relation between information structure, syntax and prosody, we present an efficient method for retrieval information focus to augment a naturalness speech synthesis. We use question answering chain to extract information focus and discover them how to move. Then, we adopt feature classification and prosody predictive modeling to deal with focus's F0 and time period and obtain them features module. Based on the features module, should significantly increase the accuracy and naturalness of speech synthesis. The rest of this paper is organized as follows. Section 2 summarizes the previously proposed theory for information focus extraction, and derives a new method. Experiments are expressed in Section 3. And experimental results are shown in Section 4. Concluding remarks are presented in the final section.\",\n \"Title: Minimum cycle bases of graphs on surfaces\\nYear: 2007\\n\\nAbstract: In this paper we study the cycle base structures of embedded graphs on surfaces. We first give a sufficient and necessary condition for a set of facial cycles to be contained in a minimum cycle base (or MCB in short) and then set up a 1-1 correspondence between the set of MCBs and the set of collections of nonseparating cycles which are in general positions on surfaces and are of shortest total length. This provides a way to enumerate MCBs in a graph via nonseparating cycles. In particular, some known results such as P.F. Stadler's work on Halin graphs [Minimum cycle bases of Halin graphs, J. Graph Theory 43 (2003) 150-155] and Leydold and Stadler's results on outer-planar graphs [Minimum cycle bases of outerplanar graphs, Electronic J. Combin. 5(16) (1998) 14] are concluded. As applications, the number of MCBs in some types of graphs embedded in lower surfaces (with arbitrarily high genera) is found. Finally, we present an interpolation theorem for the number of one-sided cycles contained in MCB of an embedded graph.\",\n \"Title: Bisingular maps on the sphere and the projective plane\\nYear: 2000\\n\\nAbstract: A map is bisingular if each edge is either a loop or an isthmus (i.e., on the boundary of the same face). In this paper we study the number of rooted bisingular maps on the plane or projective plane and also we present formulae for such maps with up to three or more parameters: the root valency, the number of isthmus, the number of essential loops, and the number of planar loops.\",\n \"Title: Lower Bound of the Number of Maximum Genus Embeddings and Genus Embeddings of K12s+7.\\nYear: 2011\\n\\nAbstract: In this paper, we study lower bound of the number of maximum orientable genus embeddings (or MGE in short) for a loopless graph. We show that a connected loopless graph of order n has at least 1/4 gamma M-(G) Pi(upsilon is an element of V(G)) (d(upsilon) - 1)! distinct MGE's, where gamma(M) (G) is the maximum orientable genus of G. Infinitely many examples show that this bound is sharp (i.e., best possible) for some types of graphs. Compared with a lower bound of Stahl (Eur J Combin 13:119-126, 1991) which concerns upper-embeddable graphs (i.e., embedded graphs with at most two facial walks), this result is more general and effective in the case of (sparse) graphs permitting relative small-degree vertices. We also obtain a similar formula for maximum nonorientable genus embeddings for general graphs. If we apply our orientable results to the current graph G (s) of K (12s+7), then G (s) has at least 2(3s) distinct MGE's.This implies that K (12s+7) has at least (22) (s) nonisomorphic cyclic oriented triangular embeddings for sufficient large s.\",\n \"Title: The crossing number of the circular graph C(2m + 2, m)\\nYear: 2005\\n\\nAbstract: The circular graph C(n,m) is such a graph that whose vertex set is ⌈v0,v1,v2,...,vn-1⌉ and edge set is ⌈vivi+1,vivi+m|i=0,1,..., n-1⌉, where m,n are natural numbers, addition is modulo n, and 2≤m≤⌊n/2⌋. This paper shows the crossing number of the circular graph C(2m+2,m)(m≥3) is m+1. © 2005 Elsevier B.V. All rights reserved.\",\n \"Title: Counting 2-Connected 4-Regular Maps on the Projective Plane.\\nYear: 2014\\n\\nAbstract: In this paper the number of rooted (near-) 4-regular maps on the projective plane are investigated with respect to the root-valency, the number of edges, the number of inner faces, the number of nonroot-vertex-loops, the number of nonroot-vertex-blocks. As special cases, formulae for several types of rooted 4-regular maps such as 2-connected 4-regular projective planar maps, rooted 2-connected (connected) 4-regular projective planar maps without loops are also presented. Several known results on the number of 4-regular maps on the projective plane are also concluded. Finally, by use of Darboux's method, very nice asymptotic formulae for the numbers of those types of maps are given.\",\n \"Title: A tunable directional coupler with a wide tuning range of coupling ratios\\nYear: 2014\\n\\nAbstract: A tunable microwave 90-degree directional coupler with a wide tuning range of coupling ratios is introduced in this paper. The architecture of this device is designed based on a fully symmetrical structure. Two varactor diodes loaded to the side of the device are used as the tuning elements. With different biasing voltage, the output power ratio between the two output ports (Port 2 and Port 3) can be easily tuned. During the tuning, very good isolation and low return loss are always kept. In the theoretical discussion, the general design equations are presented. Also, a sample circuit working at 1 GHz was made and tested to verify the design theory. The measurement results of the prototype show a good agreement with the design theory.\",\n \"Title: Reconfigurable microwave couplers with dynamic performance control\\nYear: 2014\\n\\nAbstract: Two kinds of reconfigurable microwave couplers are presented in this paper. The first one is a 90-degree branch-line coupler with a wide range of tunable coupling ratios. Especially, when its coupling ratio is tuned to be 1, this coupler becomes a crossover. The second one possesses a reconfigurable performance between a rat-race coupler and a 90-degree coupler. Both of the devices have a symmetrical structure, and varactors are loaded to the couplers as the tuning elements. By applying suitable control voltages, the reconfigurable performance is realized. Closed-form equations are derived to theoretically analyze the proposed devices. To further verify the design theory, both structures are simulated. Moreover, the first coupler is fabricated and characterized. Good performance is achieved in both simulation and measurement results.\",\n \"Title: Finding a shortest cycle in a subspace of the cycle space of a graph\\nYear: 2015\\n\\nAbstract: Thomassen's 3-path-condition shows that it is relatively easy for one to find a shortest cycle in a collection of cycles beyond a subspace of the cycle space of a connected graph and the real challenge is to find a shortest cycle contained in a given subspace of the cycle space of a graph. In this article we investigate the shorter cycle structures in a given subspace of a graph and find a set of cycles in a given graph containing much information about short cycles. We show that for a large range of subspaces of a graph satisfying a \\\\\\\"parity condition\\\\\\\", there exists a polynomial time algorithm to find a shortest cycle in these subspaces. This makes a unified treatment of several famous algorithms. Finally we provide lower bounds of some types of short cycles in embedded graphs.\",\n \"Title: A note on graph proper total colorings with many distinguishing constraints.\\nYear: 2016\\n\\nAbstract: •Graph coloring theory has a wide range of applications in many scientific fields. As an application, graph distinguishing colorings may be connected with the frequency assignment problem in wireless communication. The vertices (nodes) of graphs (networks) represent transmitters, the set C[u,f] of colors assigned to a vertex u and the edges (links) incident to u under a total coloring f indicates the frequencies usable. One constrain C[u,f]≠C[v,f] ensures the corresponding two stations u, v can operate on a wide range of frequencies without the danger of interfering with each other. We propose new total colorings having more constraints for researching deeply the frequency assignment problem. Under a proper total coloring f of a simple graph G, f(u) and f(uv) are the color assigned to a vertex u and the color assigned to an edge uv, respectively. We use C(f,u) to denote the set of colors assigned to the edges incident to u, C〈f,u〉 the union of f(u) and the set of colors assigned to the neighbors of u, so we have other two color sets C[f,u]=C(f,u)∪{f(u)}, and C2[f,u]=C(f,u)∪C〈f,u〉. We say f an adjacent vertex distinguishing total coloring (AVDTC) of G if one constraint C[f,u]≠C[f,v] holds for each edge uv of G, and the minimum number of k colors required for which G admits an AVDTC is denoted as χas″(G), which is related with a conjecture: χas″(G)≤Δ(G)+3, where Δ(G) is the maximum degree. We call f a 4-adjacent vertex distinguishing total coloring (4-AVDTC) of G if four distinguishing constraints C(f,x)≠C(f,y), C〈f,x〉≠C〈f,y〉, C[f,x]≠C[f,y] and C2[f,x]≠C2[f,y] hold simultaneously true for every edge uv of G, and the least number of k colors required for which G admits a k-4-AVDTC is denoted by χ4as″(G). We conjecture χ4as″(G)≤Δ(G)+4 if any edge uv of G holds that the set of neighbors of the vertex u differs from the set of neighbors of the vertex v.\",\n \"Title: Finding Shorter Cycles in a Weighted Graph.\\nYear: 2016\\n\\nAbstract: In this paper we investigate the structures of short cycles in a weighted graph. By Thomassen’s \\\\(3\\\\)-path-condition theory (Thomassen in J Comb Theory Ser 48:155–177, 1990), it is easy to find a shortest cycle in a collection of cycles beyond a subspace of the cycle space of a graph. What is more difficult for one to do is to find a shortest cycle within a subspace of the cycle space in polynomial time. By using the Dijkstra’s algorithm (Dijkstra in Numer Math 1:55–61, 1959) we find a collection \\\\(\\\\mathcal {C}\\\\) of cycles containing many types of short cycles within a given subspace of the cycle space of a graph and this implies a polynomial time algorithm (called extended fundamental cycle algorithm) to locate all the possible shortest cycles in a weighted graph. In the case of unweighted graphs, the algorithm may also find every shortest even cycle in a graph, this greatly improved a result of Grötschel and Pulleyblank (Oper Res Lett 1:23–27, 1981/82), Monien (Computing 31:355–369, 1983), Yuster and Zwick (SIAM J Discrete Math 10:209–222, 1997). In fact, our algorithm shows that there are at most \\\\(O(n^4)\\\\) many such short cycles in an unweighted graph of order \\\\(n\\\\). Further more, our fundamental cycle method may find a minimum cycle base (or simply MCB as some scholars named) in the cycle space of a graph. Since the structure of MCB’s is unique (Ren and Deng in Discrete Math 307:2654–2660, 2007), this shows that, in the sense, cycles in a MCB are nearly-fundamental (i.e., each element in a MCB is a sum of at most two fundamental cycles). This provides a new way to study MCB.\",\n \"Title: Workspace Calculating And Kinematic Modelling Of A Flexible Continuum Manipulator Constructed By Steel-Wires\\nYear: 2015\\n\\nAbstract: Purpose - The purpose of this paper is to present a new method to establish a kinematic model for a continuum manipulator, whose end can be controlled to move in a three-dimensional workspace. A continuum manipulator has significant advantages over traditional, rigid manipulators in many applications because of its ability to conform to the environment. Moreover, because of its excellent flexibility, light weight, low energy consumption, low production cost, it has a number of potential applications in areas of earthquake relief, agricultural harvesting, medical facilities and space exploration.Design/methodology/approach - This paper uses basic theory of material mechanics to deduct motion equations of the manipulator. Unlike other published papers, the manipulator is not based on segments tactics, but regarded as an integrated flexible system, which simplifies its kinematics modelling and motion controlling. The workspace of the manipulator is analysed by theoretical deducing and simulation modelling. For verification of the presented theory, simulation based on ADAMS software was implemented, while a prototype of the manipulator was developed. Both the software simulation and prototype experiment show that the theoretical analysis in this paper is reasonable. The manipulator can move accurately along the desired trajectories.Findings - This paper developed a novel and fully continuous manipulator driven by steel wires. A kinematic model of the manipulator was established. The physical manipulator developed for verifying the kinematic model can effectively track the prescribed trajectory. The presented kinematic model agrees with not only the simulation but also with the experiment.Research limitations/implications - The manipulator presented in this paper is constructed by steel wires. It possesses the advantages of structural continuity, high flexibility and low production cost. It can be extensively used in many fields, such as search and rescue robotic systems. The limitation of this research is that the dynamic model of the manipulator is not yet clear, which is one of the directions for future research.Practical implications - The manipulator breaks through the limitation of the joint-type or flexible-link-type manipulator, which can also be extensively used in many fields such as search and rescue robotic systems.Social implications - The manipulator developed in this paper, currently, is a prototype under the project of \\\"Automatic Picking Manipulator Research\\\". It possesses a good market value.Originality/value - The value of this research is that the manipulator breaks through the limitation of the joint-type or flexible-link-type manipulator and establishes the kinematic model for a fully continuous manipulator by a simple strategy. This is the first study that uses such a strategy for establishing the motion equations of a monolithic continuum manipulator.\",\n \"Title: L(2, 1)-labeling of a circular graph.\\nYear: 2015\\n\\nAbstract: In this paper the A-number of the circular graph C(km,m) is shown at most 9 where m >= 3 and k >= 2, and the lambda-number of the circular graph C(km+s, m) is shown at most 15 where m >= 3, k >= 2 and 1 <= s <= m - 1. In particular, the lambda-numbers of C(2m, m) and C(n, 2) are determined, which are at most 8. All our results indicates that the Griggs and Yeh's conjecture holds for circular graphs. The conjecture says that for any graph G with maximum degree Delta >= 2, lambda(G) <= Delta(2). Also, we determine A-numbers of C(n, 3), C(n, 4) and C(n, 5) if n equivalent to 0(mod 7).\",\n \"Title: Information Retrieval Using PU Learning Based Re-ranking\\nYear: 2008\\n\\nAbstract: In this paper, we describe our approach for information retrieval for question answering (IR4QA) on simple Chinese language of NTCIR-7 tasks. Firstly, we use both bi-grams and single Chinese characters as index units and use OKAPI BM25 as retrieval model. Secondly, we re-rank all documents' orders for the first retrieval documents. We focus mostly on the document re-ranking technique. We address probabilistically labeling relevant degree between the first retrieval documents and query topics. In other words, we want to know the probability of a document belongs to relevance/irrelevance class. We employ PU9' positive and unlabeled9' learning to solve this problem, and use Bayesian classifier and EM algorithm in process of computing the probability. Consequently, those relevant documents with high probability are updated rank. Lastly, we use re-ranked retrieved documents to do query expansion. Evaluation at NTCIR-7 shows that our group achieves 0.3862 and 0.3806 MAP based on\",\n \"Title: Multi-Strategy Question Answering System for NTCIR-7 C-C Task\\nYear: 2008\\n\\nAbstract: In NTCIR-7, ACLIA task focus on more complex questions than factoid ones. To participate in Monolingual Chinese task, we propose a multi-strategy QA system that can handle questions with different types. Basic steps of this system are described as follow: first, pattern-based question type analysis is performed to classify questions of four types, then an Information Retrieval method is utilized to retrieve and re-rank documents that may contain correct answers; after that, we deal retrieved results with different strategies including heuristic rules, pattern matching and web knowledge bases; finally, nuggets are extracted from answer candidates and formed as the results. The evaluation result shows that our system achieves 43.29% average F-score(beta=3). Keywords: NTCIR-7, Multi-Strategy Question Answering, pattern matching, web knowledge\",\n \"Title: Semantic Role Labeling for Biomedical Corpus Using Maximum Entropy Classifier.\\nYear: 2015\\n\\nAbstract: Semantic role labeling (SRL) is a natural language processing (NLP) task that finds shallow semantic representations from sentences. In this paper, we construct a biomedical proposition bank and train a biomedical semantic role labeling system that can be used to facilitate relation extraction and information retrieval in biomedical domain. Firstly, we construct a proposition bank on the basis of the GENIA TreeBank following the Penn PropBank annotation. Secondly, we use GenPropBank to train a biomedical SRL system, which uses maximum entropy as a classifier. Our experimental results show that a newswire SRL system that achieves an F1 of 85.56 % in the newswire domain can only maintain an F1 of 65.43 % when ported to the biomedical domain. By using our annotated biomedical corpus, we can increase that F1 by 19.2 %.\",\n \"Title: Odd components of co-trees and graph embeddings.\\nYear: 2016\\n\\nAbstract: In this paper we investigate the relation between odd components of co-trees and graph embeddings. We show that any graph G must share one of the following two conditions: (a)¿for each integer h such that G may be embedded on Sh, the sphere with h handles, there is a spanning tree T in G such that h = 1 2 ( β ( G ) - ω ( T ) ) , where β(G) and ω(T) are, respectively, the Betti number of G and the number of components of G - E ( T ) having odd number of edges; (b)¿¿¿for every spanning tree T of G, there is an orientable embedding of G with exact ω ( T ) + 1 faces. This extends Xuong and Liu's theorem 9,13 to some other (possible) genera. Infinitely many examples show that there are graphs which satisfy (a) but (b). Those make a correction of a result of Archdeacon 2, Theorem¿1.\",\n \"Title: Adjacent vertex distinguishing total colorings of graphs with four distinguishing constraints.\\nYear: 2016\\n\\nAbstract: Frequency assignment problem was produced in researching mobile communication networks. A proper total coloring of a graph G is a coloring of both edges and vertices of G such that no two adjacent or incident elements receive the same color. As known, the vertex distinguishing total coloring is one of suitable tools for investigating the frequency assignment problem. We introduce a new graph total coloring, called (4)-adjacent vertex distinguishing total coloring ((4)- AVDTC), in tins paper. Our coloring contains the adjacent vertex distinguishing total coloring. The minimum number of colors required for every (4)-AVDTC of G is called the (4)-AVDTC chromatic number of G. We will show that using at most Delta(G) + 4 colors can do at least 4 different adjacent vertex distinguishing actions to some communication networks G. The exact (4)-AVDTC chromatic: numbers of several classes of graphs are determined here and a problem is presented.\",\n \"Title: Study on the English Corresponding Unit of Chinese Clause\\nYear: 2016\\n\\nAbstract: This paper annotates the English corresponding units of Chinese clauses in Chinese-English translation and statistically analyzes them. Firstly, based on Chinese clause segmentation, we segment English target text into corresponding units (clause) to get a Chinese-to-English clause-aligned parallel corpus. Then, we annotate the grammatical properties of the English corresponding clauses in the corpus. Finally, we find the distribution characteristics of grammatical properties of English corresponding clauses by statistically analyzing the annotated corpus: there are more clauses (1631,74.41%) than sentences (561,25.59%); there are more major clauses (1719,78.42%) than subordinate clauses (473,21.58%); there are more adverbial clauses (392,82.88%) than attributive clauses (81,17.12%) and more non-defining clauses (358,75.69%) than restrictive relative clauses (115,24.31%) in subordinate clauses; and there are more simple clauses (1142,52.1%) than coordinate clauses (1050,47.9%).\",\n \"Title: Sports News Generation from Live Webcast Scripts Based on Rules and Templates\\nYear: 2016\\n\\nAbstract: With the dramatic increase of the live webcast scripts about sports, it is an urgent demand to write and publish a sports news article immediately after a sports game. However, so far, the sports news articles are usually written by human experts or journalists, and the manual writing of sports news is time-consuming and inefficient. This paper describes our system on the sports news generation from live webcast scripts task. On one hand, our system extracts the important events occurring in the time period from the live webcast scripts according to the rules, and on the other hand, our system generates a brief summary from the live webcast scripts about the football matches. According to the characteristic of live webcast scripts, we adopt an approach to sentence extraction and template generation from live webcast scripts. The evaluation results show that our system is feasible in sports news generation from live webcast scripts.\",\n \"Title: The Number of 1-Factors and Edge-Colorings of Mobius Ladder Graphs and Triangular Embeddings of K12m+7.\\nYear: 2016\\n\\nAbstract: In this paper we study the number of 1-factors and edge-colorings of the Mobius ladder graphs. We find exact formulae for such numbers and show that there are exponentially many 1-factors and edge-colorings in such graphs. As applications, we show that every \\\"men-made\\\" triangular embedding for K12m+7 by the current graphs by these of Youngs and Ringel permits exponentially many \\\"Grunbaum colorings\\\" (i.e.,3-edge-colored triangulations in such a way that each triangle receives three distinct colors.)\",\n \"Title: The orientable genus of the generalized Petersen graph P(km, m).\\nYear: 2017\\n\\nAbstract: In the paper we show that the orientable genus of the generalized Petersen graph P(km, m) is at least km/4-m/2-km/4m-4+1 if m >= 4 and k > 3. We determine the orientable genera of P(3m, m), P(4k, 4), P(4m, m) if m >= 4, P(6m, m) if m equivalent to 0 (mod 2) and m >= 6, and so on.\",\n \"Title: A new formula for the decycling number of regular graphs.\\nYear: 2017\\n\\nAbstract: The decycling number ∇(G) of a graph G is the smallest number of vertices which can be removed from G so that the resultant graph contains no cycle. A decycling set containing exactly ∇(G) vertices of G is called a ∇-set. For any decycling set S of a k-regular graph G, we show that |S|=β(G)+m(S)k−1, where β(G) is the cycle rank of G, m(S)=c+|E(S)|−1 is the margin number of S, c and |E(S)| are, respectively, the number of components of G−S and the number of edges in G[S]. In particular, for any ∇-set S of a 3-regular graph G, we prove that m(S)=ξ(G), where ξ(G) is the Betti deficiency of G. This implies that the decycling number of a 3-regular graph G is β(G)+ξ(G)2. Hence ∇(G)=⌈β(G)2⌉ for a 3-regular upper-embeddable graph G, which concludes the results in [Gao et al., 2015, Wei and Li, 2013] and solves two open problems posed by Bau and Beineke (2002). Considering an algorithm by Furst et al., (1988), there exists a polynomial time algorithm to compute Z(G), the cardinality of a maximum nonseparating independent set in a 3-regular graph G, which solves an open problem raised by Speckenmeyer (1988). As for a 4-regular graph G, we show that for any ∇-set S of G, there exists a spanning tree T of G such that the elements of S are simply the leaves of T with at most two exceptions providing ∇(G)=⌈β(G)3⌉. On the other hand, if G is a loopless graph on n vertices with maximum degree at most 4, then ∇(G)≤n+12,if G is 4-regular,n2,otherwise.The above two upper bounds are tight, and this makes an extension of a result due to Punnim (2006).\",\n \"Title: Recognizing Textual Entailment Using Inference Phenomenon\\nYear: 2017\\n\\nAbstract: Inference phenomena refer to inference relations in local fragments between two texts. Current research on inference phenomenon focuses on the construction of data annotation, whereas there are few research on how to identify those inference phenomena in texts, which will contributes to improving the performance of recognizing textual entailment. This paper proposes an approach, which uses inference phenomena to recognize entailment in texts. In the approach, the task of recognizing textual entailment is formalized as two problems, that is, inference phenomenon identification and entailment judgment, then a joint model is employed to combine such two related subtasks, which is helpful to avoid error propagation. Experimental results show that the approach performs efficiently for identifying inference phenomena and recognizing entailment at the same time.\",\n \"Title: Building A Parallel Corpus With Bilingual Discourse Alignment\\nYear: 2017\\n\\nAbstract: This paper describes a discourse resource, namely a Chinese-English parallel corpus, based on the idea of bilingual discourse alignment. We introduce a bilingual collaborative annotation approach, which annotates English discourse units based on Chinese ones, and annotates Chinese discourse structure based on English ones subsequently. Such approach can ensure full discourse structure alignment between parallel texts, and reduce cost for annotating texts of two languages as well. Annotation Evaluation of the parallel corpus justifies the appropriateness of the discourse alignment framework to parallel texts.\",\n \"Title: Extractive Single Document Summarization via Multi-feature Combination and Sentence Compression.\\nYear: 2017\\n\\nAbstract: In this paper, we attempt to extract and generate the short summary for the news article with the length limit of 60 Chinese characters. Firstly, we preprocess the news article by segmenting sentences and words, and then extract four kinds of central words to form the keyword dictionary based on parsing tree. After that, the four kinds of features, i.e. the sentence weight, the sentence similarity, the sentence position and the length of sentence, will be employed to measure the significance of each sentence. Finally, we extract two sentences in the descending order of significance score and compress them to get the summary for each news article. This approach can analyze the grammatical elements from original sentences in order to generate compression rules and trim syntactic elements according to their parsing trees. The evaluation results show that our system is efficient in Chinese news summarization.\",\n \"Title: Answer Ranking Based on Language Phenomenon Recognition.\\nYear: 2018\\n\\nAbstract: Answer Ranking is one of the core tasks in Question Answering, which greatly depends on the performance of answer ranking. This paper introduces an approach of answer ranking based on language phenomenon identification, that is, identifying language phenomena between a question and its answer sentence candidates, then computing entailment confidence score between the question and each candidate. Finally, an answer ranking is made according to such scores. This paper also introduces a joint model for both language phenomenon identification and entailment recognition task, in order to avoid error propagation to some extent, and make the two tasks learn to each other for a better overall performance as well. Experimental results show that the joint learning of language phenomenon identification and entailment recognition is an effective way for answer ranking.\",\n \"Title: A Comparative Study on the Coordinate Relation of Chinese Official Documents in Mainland, Hong Kong and Macau.\\nYear: 2018\\n\\nAbstract: This paper investigates the coordinate relation in Mainland Chinese, Hong Kong Chinese and Macau Chinese, including explicit relations, implicit relations and their parallel items. In order to conduct the comparative study, a corpus including official documents of Mainland China, Hong Kong and Macau has been built. The study shows that the frequency of the explicit coordinate relation appearing in Hong Kong (53.5%) and Macao texts (23.1%) is much higher than that in Mainland China texts (1.5%), and the explicit coordinate relation occurs most frequently in Hong Kong texts. The study also shows that the connective types in Hong Kong (59 types) and Macao texts (21 types) are much more than that in Mainland China texts (11 types). Such differences are probably derived from the English influence on Hong Kong and Macau Chinese, according to the comparative results of the coordinate relation in English and Chinese texts of Hong Kong and Macau.\",\n \"Title: New formulae for the bipartite vertex frustration and decycling number of graphs.\\nYear: 2019\\n\\nAbstract: Let ∇2(G), φ(G) and ∇(G) denote the bipartite vertex frustration, bipartite edge frustration and decycling number of a graph G, respectively. In this paper, we show that ∇2(G)=|V(G)|−max {α(G−E(B)):B is a spanning bipartite subgraph of G}, which provides a new method to estimate the bipartite vertex frustration in terms of bipartite edge frustration for graphs. Using the formula above and some known results on the bipartite edge frustration, we derive several new results on the bipartite vertex frustration, including some that are equalities. Further, we study the bipartite vertex frustration of five classes of composite graphs. Finally, we present a formula for the decycling number: ∇(G)=|V(G)|−max{α(G−E(F)):FisaspanningforstofG}. Based on this result, we determine the decycling numbers of many certain graphs. In addition, this formula gives a new way for dealing with the decycling number problem of dense graphs.\",\n \"Title: Study on stretch-retractable single-section continuum manipulator.\\nYear: 2019\\n\\nAbstract: This paper proposes a stretch-retractable single-section (SRSS) continuum manipulator. Its backbone is composed by a series of springs. Thus, this continuum manipulator owns feature of a large-scale stretch-retractable ability. With such a feature, different from traditional single-section continuum manipulator which distal end moves in a curved surface, the presented manipulator's distal end has a solid work space. The kinematic model including the variable parameter of backbone length was established, and the stretch-retractable workspace was analyzed, with which the driving strategy was proposed. The prototype was made out based on the concept of the large-scale stretch-retractable backbone. The driving patterns with single parameter input and the driving patterns with multi parameter inputs were carried out. The tests verified the presented SRSS continuum manipulator.\",\n \"Title: Neural Networks For Bacterial Named Entity Recognition\\nYear: 2018\\n\\nAbstract: Bacterial named entity recognition is a challenging task in biomedical field. The task is typically modeled as a sequence labeling problem, and existing work mainly adopts discrete models such as CRF (Conditional Random Fields), requiring a large amount of hand-designed features with domain experience. To address this issue, this paper explores a neural network model for the task. We empirically study the effect of word embeddings and character embeddings on the task by extending a CRF baseline using neural networks. Results show the proposed neural network model achieves competitive performance, outperforming the current best discrete model. Meanwhile, the performance can be further improved by integrating neural and discrete features.\",\n \"Title: Decycling Number of a class of 4-regular graphs.\\nYear: 2018\\n\\nAbstract: Let del(G) denote the minimum number of vertices of G whose removal results in an acyclic graph (i.e., a forest). Such a number del(G) is called the decycling number of graph G. In this paper, we discuss the decycling number of a class of 4-regular graphs.\",\n \"Title: The decycling number and maximum genus of cubic graphs.\\nYear: 2018\\n\\nAbstract: Let delta(G) and M(G) denote the minimum size of a decycling set and maximum genus of a graph G, respectively. For a connected cubic graph G of order n, it is shown that delta(G)+M(G)=n 2+1. Applying the formula, we obtain some new results on the decycling number and maximum genus of cubic graphs. Furthermore, it is shown that the number of vertices of a decycling set S in a k-regular graph G is |S|=1k-1{(G)+c+mS-1}, where c and are the number of components of G-S and the number of edges in G[S], respectively. Therefore, S is minimum if and only if c+<-1 is minimum. As an application, this leads to a lower bound delta(G)remvoe(G)k-1 for delta(G) of a k-regular graph G. In many cases this bound may be sharp.\",\n \"Title: Stretched Backboneless Continuum Manipulator Driven By Cannula Tendons\\nYear: 2018\\n\\nAbstract: Purpose - The purpose of this paper is to present a stretched backboneless continuum manipulator, which aims to provide sufficient inner room for potential transportation of objects or fixture of necessary devices, and to reduce the number of motors for reduction of the weight of the system.Design/methodology/approach -A mathematical model of the presented manipulator is established in this paper. To verify the presented theory, the position of the free end was recorded by a high-resolution digital camera in experiment. According to the comparison of experimental values and theoretical values, the error is less than 2.5 per cent. It shows that the mathematical model and theoretical analysis are reasonable; the presented continuum manipulator can reach to desired postures and positions.Findings - This paper presents a new stretched backboneless continuum manipulator supported and driven by cannula tendons. The cannula tendons are composed of rubber tubes and glass fibers. The upper section and the lower section of the presented manipulator are driven by same motors. For steering the manipulator, switched driving strategy is developed based on the presented kinematics model. The presented manipulator possesses six degrees of freedom (DOFs) and has good performance in dealing with complex working environment. The experiment verifies the presented driving strategy.Research limitations/implications - The presented backboneless continuum manipulator has only two sections and is supported by cannula tendons. Extending this structure to further more sections is a challenge and is left for future research.Originality/value - The value of this study is to propose a stretched backboneless continuum manipulator, which can provide inner room as large as possible for potential usage and halve the number of motors, for which a switched driving strategy is put forward. As a result, the weight and complexity of the manipulator are decreased. The presented manipulator is able to move in potential complex environments and approach its objects in different postures in virtue of its high flexibility and its six DOFs.\",\n \"Title: Context-augmented convolutional neural networks for twitter sarcasm detection.\\nYear: 2018\\n\\nAbstract: Sarcasm detection on twitter has received increasing research in recent years. However, existing work has two limitations. First, existing work mainly uses discrete models, requiring a large number of manual features, which can be expensive to obtain. Second, most existing work focuses on feature engineering according to the tweet itself, and does not utilize contextual information regarding the target tweet. However, contextual information (e.g. a conversation or the history tweets of the target tweet author) may be available for the target tweet. To address the above two issues, we explore the neural network models for twitter sarcasm detection. Based on convolutional neural network, we propose two different context-augmented neural models for this task. Results on the dataset show that neural models can achieve better performance compared to state-of-the-art discrete models. Meanwhile, the proposed context-augmented neural models can effectively decode sarcastic clues from contextual information, and give a relative improvement in the detection performance.\",\n \"Title: Lower bound on the number of Hamiltonian cycles of generalized Petersen graphs\\nYear: 2020\\n\\nAbstract: In this paper, we investigate the number of Hamiltonian cycles of a generalized Petersen graph P(N, k) and prove that psi(P(N, 3) >= N center dot alpha(N) where psi(P(N, 3)) is the number of Hamiltonian cycles of P(N, 3) and alpha(N) satisfies that for any epsilon > 0, there exists a positive integer M such that when N > M, ((1-epsilon)(1-r(3))/6r(3)+5r(2)+3)(1/r)(N+2) < alpha N < ((1+epsilon)(1-r(3))/6r(3)+5r(2)+3)(1/r)(N+2), where 1/r = max {vertical bar 1/r (j)vertical bar j = 1, 2,..., 6} and each r(j) is a root of equation x(6) + x(5) + x(3) - 1 = 0, r approximate to 0.782. This shows that psi(P(N, 3) is exponential in N and also deduces that the number of 1-factors of P(N, 3) is exponential in N.\",\n \"Title: A Note on Decycling Number, Vertex Partition and AVD-Total Coloring in Graphs.\\nYear: 2018\\n\\nAbstract: This note provides a new perspective, i.e., graph embeddings on the decycling number \\\\(\\\\nabla (G)\\\\) (Beineke and Vandell in J Graph Theory 25:59–77, 1997) of a graph G. For this point, it is shown that \\\\(\\\\nabla (G)=\\\\gamma _M(G)+\\\\xi (G)\\\\) for any cubic graph G and \\\\(|S|=\\\\frac{\\\\beta (G)+m(S)}{k-1}\\\\) for any decycling set S of a k-regular graph G, where \\\\(\\\\gamma _M(G)\\\\), \\\\(\\\\xi (G)\\\\), \\\\(\\\\beta (G)\\\\) and \\\\(m(S)=c(G-S)+|E(S)|-1\\\\) (\\\\(c(G-S)\\\\) is the number of components of \\\\(G-S\\\\) and |E(S)| is the number of edges in a subgraph G[S]) are, respectively, the maximum genus, the Betti deficiency (Xuong in J Combin Theory Ser B 26:217–225, 1979), the cycle rank (Harary in Graph theory, Academic Press, New York, 1967) and the margin number of G. Meanwhile, we further confirm that (1) a cubic graph G (\\\\(G\\\\ne K_4\\\\)) has a vertex partition \\\\((V_1, V_2)\\\\) such that \\\\(V_1\\\\) is an independent set and \\\\(V_2\\\\) induces a forest and (2) a k-regular graph G with \\\\(\\\\nabla (G)=\\\\frac{\\\\beta (G)+m(S)}{k-1}\\\\) (\\\\(m(S)\\\\le 2\\\\)) has a vertex partition \\\\((S,G-S)\\\\) such that G[S] contains at most two edges and \\\\(G-S\\\\) induces a forest, where S is the smallest decycling set of G. Resorting to the above vertex partitions, we get the adjacent vertex distinguishing (AVD) total chromatic numbers of some families of graphs, and these results verify Zhang’s conjecture (Zhang in Sci China Ser A 48:289–299, 2005) that every graph with maximum degree \\\\(\\\\Delta \\\\) has an AVD-total \\\\((\\\\Delta +3)\\\\)-coloring.\",\n \"Title: Bounds for Judicious Balanced Bipartitions of Graphs.\\nYear: 2018\\n\\nAbstract: A bipartition of the vertex set of a graph is called balanced if the sizes of the sets in the bipartition differ by at most one. Bollob\\\\(\\\\acute{a}\\\\)s and Scott proved that every regular graph with m edges admits a balanced bipartition \\\\(V_{1}\\\\), \\\\(V_{2}\\\\) of V(G) such that \\\\(\\\\max \\\\{e(V_{1}), e(V_{2}) \\\\}< \\\\frac{m}{4}\\\\). Only allowing \\\\(\\\\varDelta (G)-\\\\delta (G)\\\\) =1 and 2, Yan and Xu, and Hu, He and Hao, respectively showed that a graph G with n vertices and m edges has a balanced bipartition \\\\(V_{1}\\\\), \\\\(V_{2}\\\\) of V(G) such that \\\\(\\\\max \\\\{e(V_{1}), e(V_{2}) \\\\}\\\\le \\\\frac{m}{4}+O(n)\\\\). In this paper, we give an upper bound for balanced bipartition of graphs G with \\\\(\\\\varDelta (G)-\\\\delta (G)=t-1\\\\), \\\\(t\\\\ge 2\\\\) is an integer. Our result extends the conclusions above.\",\n \"Title: Emotion Cause Detection with a Hierarchical Network\\nYear: 2021\\n\\nAbstract: Emotion cause detection plays a key role in many downstream sentiment analysis applications. Research shows that both knowledge from data and experience from linguistics help to improve the detection performance. In this paper, we propose an approach to combine them. We utilize a hierarchical framework to model emotional texts, in which the emotion is independently represented along with each word and clause in a document. We also employ linguistic features to help the model find the emotion cause. Such features by manual work help to describe deep semantic relations between emotions and their causes that are difficult to be cast by representation models. Experimental results show that the combination model helps to detect emotion cause within emotional texts with complex semantic relations.\",\n \"Title: Distributions of Near-4-Regular Maps on the Sphere and the Projective Plane\\nYear: 2021\\n\\nAbstract: Let U-n and (u) over bar (n) (A(n) and ($) over bar (n)) denote the sets of all rooted near-4-regular maps with n inner faces (n edges) on the sphere and the projective plane, respectively. Let p(m) and (p) over bar (m) be, respectively, the limit probability (as n -> infinity) of the event that the rooted vertex of a map chosen in U-n and (u) over bar (n) (A(n) and ($) over bar (n)) at random is of valency 2m. It is shown that both p(m) and (p) over bar (m) obey the asymptotic pattern characterized by the factor m(1/2): Cm-1/2(2/3)m as m -> infinity, where C is a constant depending on the type of maps, meanwhile each of q(m) and ($) over bar (m) will not satisfy the root-vertex valency distribution pattern posed in Liskovets (J Combin Theory Ser B 75, 116- 133, 1999) (i.e., q(m) = (q) over bar (m) = 0 for every natural number m). In particular, those maps can not satisfy several other classical patterns for n-edged maps.\",\n \"Title: Mean Color Numbers of Some Graphs\\nYear: 2022\\n\\nAbstract: Let mu(G) denote the mean color number of a graph G. Dong proposed two mean color conjectures. One is that for any graph G and a vertex w in G with d(w) > 1, if H is a graph obtained from G by deleting all but one of the edges which are incident to w, then it(G)> it(H). The other is that for any graph G and a vertex w in G, it(G)>.((G w) U In this paper, we show that the two conjectures hold under the condition that w is a simplicial vertex in G. And when G is a connected (n, m) graph and w is not a cut vertex in G with d(w) = n 1, if rn < + 2) n 4.5 the second conjecture holds too. The two conjectures also hold for some special cases, such as wheels and chordal graphs (Dong in J Combin Theory Ser B 87: 348-365, 2003).\",\n \"Title: Cascade Residual Capsule Network for Hyperspectral Image Classification\\nYear: 2022\\n\\nAbstract: Theconvolution neural network (CNN) has recently shown the good performance in hyperspectral image (HSI) classification tasks. Many CNN-based methods crop image patches from original HSI as inputs. However, the input HSI cubes usually contain background and many hyperspectral pixels with different land-cover labels. Therefore, the spatial context information on objects of the same category is diverse in HSI cubes, which will weaken the discrimination of spectral-spatial features. In addition, CNN-based methods still face challenges in dealing with the spectral similarity between HSI cubes of spatially adjacent categories, which will limit the classification accuracy. To address the aforementioned issues, we propose a cascade residual capsule network (CRCN) for HSI classification. First, a residual module is designed to learn high-level spectral features of input HSI cubes in the spectral dimension. The residual module is employed to solve the problem of the spectral similarity between HSI cubes of spatially adjacent categories. And then two 3-D convolution layers are exploited to extract high-level spatial-spectral features. Finally, a capsule structure is developed to characterize spatial context orientation representations of objects, which can effectively deal with the diverse spatial context information on objects of the same category in HSI cubes. The capsule module is composed of two 3-D convolution layers and the capsule structure, which is connected to the residual module in series to construct the proposed CRCN. Experimental results on four public HSI datasets demonstrate the superiority of the proposed CRCN over six state-of-the-art models.\",\n \"Title: Dynamical Analysis of Border Collision Bifurcation in One-Cycle Controlled Single-Inductor Dual-Output Boost DC-DC Converters\\nYear: 2022\\n\\nAbstract: In this paper, the evolution of three types of border collision bifurcations are investigated thoroughly for a high-order single-inductor double-output DC-DC converter with one-cycle control (OCC). Multi-piecewise inductor current with more than one border and cross-coupling effect between different output ports are prominent features of the system, resulting in unexpected period incrementing cascade and transition from periodicity to chaos as a parameter is varied. A high-order nonlinear iterative map model is proposed, which reveals the underlying mechanisms of those complicated nonstandard and unsmooth bifurcations in the multiple-output system. Additionally, theoretical analysis shows that those nonstandard bifurcations arise from the boundary collisions, and more specifically, a fixed point suddenly appears in the borderline between various regions. Besides eigenvalue loci changes abruptly at the bifurcation point, the characteristic of border collision bifurcation is the topology sequence changes. Furthermore, the parameter boundaries are given to provide useful guidance for design. Finally, PSpice circuit experiments are performed to verify the above theoretical and numerical results.\",\n \"Title: The number of 4-cycles in a graph\\nYear: 2022\\n\\nAbstract: In extremal graph theory studies, it is not yet finished to determine the exact value of ex(n; C-4) in general case. Erdos and Simonovits [10] conjectured that an n-vertex graph G with ex(n; C-4 ) + 1 edges may contain at least root n + o(root n) 4-cycles. In this paper we investigate the number of 4-cycles in a graph. We show that the number of 4-cycles in an n-vertex graph G is at least (epsilon root 4n - 3 )/4 + epsilon(2)/(2n) provided that |E(G)| = n (1 + root 4n - 3 )/4 + epsilon, where epsilon is an arbitrary positive real number. This result is an approach solving to this open problem. Furthermore, we prove that if n is large enough, then there are at least ((4 epsilon - 1)root 4n - 3 + 5)/16 + o(1) 4-cycles in an n-vertex graph with e = (n - 1)(1 + root 4n - 3 )/4 + epsilon edges which has k vertices whose degrees are mutually different, where k >= 3 root 24n +3 root 12n -(12n)(2) - 1/27 and epsilon > 0 is a real number. In addition, we get that a triangle-free graph with n vertices and e = n root n - 1/2 + epsilon edges has at least (2 epsilon(root n - 1 - 2) + 1)/4 + o(1) 4-cycles, where epsilon > 0 is an any real number and n is large enough. This shows that the weak version of Erdos and Simonovits' conjecture [10] holds for such graphs when n is sufficiently large. Finally, we obtain a bipartite version of this result. (C) 2022 Elsevier Inc. All rights reserved.\",\n \"Title: A Fast Direct Position Determination Algorithm for LFM Signal Based on Spectrum Detection\\nYear: 2022\\n\\nAbstract: For the purpose of simultaneously estimating and locating the linear frequency modulation (LFM) emitter with unknown parameters, an innovative approach, i.e., Fast Direct Position Determination (FDPD), is introduced. The proposed algorithm is based on maximum likelihood estimation (MLE) and spectrum detection. To improve the accuracy and overcome the dramatic complexity of plain maximum likelihood formulation, we further derive the objective function equation of Direct Position Determination (DPD) algorithm and present an enhanced strategy to solve the highly nonlinear optimization problem. By combining the two-step localization method, one-step localization method, and short-time Fourier transform (STFT), our approach realizes jointly estimation of the transmitted signal parameters and emitter localization. Simulation results show that the proposed method is superior compared to the existing DPD, and two-step localization algorithms in terms of localization error and computational complexity, especially for low signal-to-noise ratio (SNR).\",\n \"Title: The Number of Copies of $$K_{2,t+1}$$ K 2 , t + 1 in a Graph\\nYear: 2022\\n\\nAbstract: It is not yet finished to locate the exact value of ex\\n \\n \\n \\n $$(n;K_{2,t+1})$$\\n \\n in the extremal graph theory. Füredi (J Combin Theory Ser A 75(1):141–144, 1996) proved that the Hyltén-Cavallius’ bound \\n \\n \\n \\n $$\\\\frac{n}{4}\\\\left( \\\\sqrt{4tn-4t+1}+1 \\\\right)$$\\n \\n is asymptotically best possible for ex\\n \\n \\n \\n $$(n;K_{2,t+1})$$\\n \\n . In this paper we investigate the number of copies of \\n \\n \\n \\n $$K_{2,t+1}$$\\n \\n (\\n \\n \\n \\n $$t\\\\ge 2$$\\n \\n ) in a graph. We show that an n-vertex graph G contains at least \\n \\n \\n \\n $$\\\\frac{\\\\epsilon }{t+1}\\\\sqrt{4tn-4t+1}+\\\\frac{8t\\\\epsilon ^2}{(t+1)(n-1)}+\\\\frac{2\\\\epsilon ^2}{(t+1)n}$$\\n \\n copies of \\n \\n \\n \\n $$K_{2,t+1}$$\\n \\n provided that \\n \\n \\n \\n $$|E(G)|=\\\\frac{n}{4}\\\\left( \\\\sqrt{4tn-4t+1}+1 \\\\right) +\\\\epsilon$$\\n \\n , where \\n \\n \\n \\n $$\\\\epsilon >0$$\\n \\n is a real number. Furthermore, we also obtain a formula for the number of copies of \\n \\n \\n \\n $$K_{2,t+1}$$\\n \\n in a graph.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":63,"string":"63"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":286,"string":"286"}}},{"rowIdx":287,"cells":{"question_id":{"kind":"string","value":"Robert St Amant"},"question":{"kind":"string","value":"Generate an abstract for the title \"HabilisDraw DT: a bimanual tool-based direct manipulation drawing environment\" using the following items: 1. Two-handed tool-based drawing environment\n2. Persistent tools\n3. Bimanual input\n4. Desktop metaphor\n5. Improved interface usability"},"answer":{"kind":"string","value":"In this paper, we present a two-handed tool-based drawing environment based on the principles originally incorporated into the HabilisDraw interactive drawing system. These principles include persistent tools that embody intuitive aspects of their physical counterparts and an approach to interface learnability that capitalizes on the user's inherent ability to use tools both separately and in conjunction with other tools. In addition to these principles, the DiamondTouch variation of HabilisDraw (HabilisDraw DT) extends the physical-virtual tool correlation with bimanual input via the MERL DiamondTouch input device and a close adherence to the direct manipulation interaction model. This paper presents the HabilisDraw interface, explores the benefits of a desktop metaphor that closely mimics the behavior of two-dimensional tools and objects in a drawing environment, and argues for the applicability of the system's fundamental principles for improving interface usability in the future."},"correct_answer":{"kind":"string","value":"In this paper, we present a two-handed tool-based drawing environment based on the principles originally incorporated into the HabilisDraw interactive drawing system. These principles include persistent tools that embody intuitive aspects of their physical counterparts and an approach to interface learnability that capitalizes on the user's inherent ability to use tools both separately and in conjunction with other tools. In addition to these principles, the DiamondTouch variation of HabilisDraw (HabilisDraw DT) extends the physical-virtual tool correlation with bimanual input via the MERL DiamondTouch input device and a close adherence to the direct manipulation interaction model. This paper presents the HabilisDraw interface, explores the benefits of a desktop metaphor that closely mimics the behavior of two-dimensional tools and objects in a drawing environment, and argues for the applicability of the system's fundamental principles for improving interface usability in the future."},"documents":{"kind":"list like","value":["Title: User Interface Softbots\nYear: 2000\n\nAbstract: s, effectors, and controller providea general-purpose means of managing interactive applications,through the same medium as a real user.System componentsConceptually, we can break down ibot functionality intothree components, as we might do with any physically realizedrobot: perception, action, and control.PerceptionIbot perception relies on conventional image processingtechniques. Object identification follows a three-stage processof segmentation, feature computation, and...","Title: A planner for exploratory data analysis\nYear: 1996\n\nAbstract: Statistical exploratory data analysis (EDA) poses a difficult search problem. The EDA process lends itself however to a planning for- mulation. We have built a system, called AIDE, to help users explore data. Atl)F~ re- lies or, partial hierarchical planning, a form of planning appropriate for tasks in complex. uncertain environments. Our description of the EDA task and the AIDE system provides a case study of the applicat ion of plamdng to a novel domain.","Title: Navigation and planning in a mixed-initiative user interface\nYear: 1997\n\nAbstract: Mixed-initiative planning is one approach to building an intelligent decision-making environment. A mixed-initiative system shares decision-making responsibility with the user such that it acts sometimes as a tool, to be directly applied to a specific task, and other times as an autonomous problem-solver. In the best case, the user can delegate the details of a task to the automated system without giving up the ability to guide and review the decision-making process. We have developed a simple mixed-initiative planner that incorporates a view of problem-solving as navigation. We have explored this notion in two different applications: exploratory statistical analysis and layout design for user interface dialogs. This paper discusses navigation issues in the context of these two systems, the potential benefits of the approach, and some implications for user interface design.","Title: Environment modification in a simulated human-robot interaction task:: experimentation and analysis\nYear: 2003\n\nAbstract: This paper describes a novel approach to human-robot interaction, in which a user modifies a robot's environment to constrain its actions, rather than programming its controller. An HRI simulation of a maze navigation task is presented. An empirical evaluation shows that for this task, users prefer an environment modification strategy rather than a programming strategy as the difficulty of the task increases. Further, user alternation between the two types of strategy follows a clear pattern. A preliminary model extending the HRI simulation, one which allows the specification of more general navigation environments, is also presented","Title: The user interface as an agent environment\nYear: 2000\n\nAbstract: Mainstream planning systems make a number of assump- tions about their environments, in areas such as the pre- dictability of action effects, accessibility to state informa- tion, and static behavior of the environment. We find a striking correspondence between these assumptions and the properties of graphical user interfaces. We have developed a novel type of interface agent, called an ibot, to exploit these correspondences. Ibots can interact with off-the-shelf appli- cations through the user interface rather than programmati- cally, gaining access to functionality not readily available to artificial agents by other means. In this paper we describe the relationship between these agents and the theoretical and heuristic properties of user interfaces. We demonstrate the feasibility of our approach to interface agents with an imple- mented prototype that interacts with an unmodified applica- tion for graphical illustration.","Title: A glove for tapping and discrete 1D/2D input\nYear: 2012\n\nAbstract: This paper describes a glove with which users enter input by tapping fingertips with the thumb or by rubbing the thumb over the palmar surfaces of the middle and index fingers. The glove has been informally tested as the controller for two semi-autonomous robots in a a 3D simulation environment. A preliminary evaluation of the glove's performance is presented.","Title: An environment for user interface softbots\nYear: 2002\n\nAbstract: A user interface softbot is a software agent that controls an interactive system through the graphical user interface, relying on visual information from the system rather than an application programming interface or access to source code. Interface softbots have acted as autonomous agents in applications such as drawing and data recording, and the core vision processing algorithms have been incorporated into cognitive models for simple problem-solving tasks. Building interface softbots is still a time-consuming task, unfortunately, requiring experience with complex program components as well as the details of the visual interface. We have developed a prototype development environment that facilitates the development of interface softbots, streamlining the programming process and making it more accessible to new developers.","Title: An experiment with navigation and intelligent assistance\nYear: 1998\n\nAbstract: Modern user interfaces make extensive use of navigation, a metaphor based on wayfinding in a physical space. Navigation can be an effective solution for many problems in understanding and manipulating a complex information space. Our work is in the area of intelligent assistance for decision support environments, where assistance may take the form of automatically exploring decision alternatives, recording justifications for actions, testing global consistency of local results, and generating audit trails, among other activities. This paper describes an experimental evaluation of assisted search in an artificial environment using navigation as a communication medium, under conditions that vary the quality of assistance.","Title: A User Modeling Design Tool Based on a Cognitive Architecture for Comparing Interfaces\nYear: 2002\n\nAbstract: Usability evaluation has long been recognized as an indispensable part of the development of interactive software. Evaluation can still be a difficult and labor- intensive task with conventional tools and user studies, however. Results can vary with the knowledge and experience of the evaluator and with the subjects. We describe an approach to evaluation, based on cognitive modeling, that will alleviate some of these problems. We are building a general-purpose, cross- platform architecture in which user performance in an interactive environment is simulated by a cognitive model. The results of the model can be analyzed and fed back into the development lifecycle. This project is still preliminary, but progress is accelerating.","Title: Introductory AI educational resources on the web\nYear: 2001\n\nAbstract: Fortunately for people seeking to learn more about artificial intelligence, a wide range of general and introductory educational materials related to AI is available on the Web. The Web resources described below, available both in electronic form and as pointers to conventional media such as books or videos, are not, however, of interest just to university educators and their students. Many of them are of broad scope and are useful to information technology specialists or AI practitioners seeking a starting-off point from which to improve their knowledge of the field. Some of the materials listed here will also be of use to educators in high schools or middle schools where AI topics may play a role in course curricula.","Title: IBOTS: agent control through the user interface\nYear: 1999\n\nAbstract: This paper describes an ibot, a specialized software agent that exists in the environment of the user interface. Such an agent interacts with applications through the same medium as a human user. Its sensors process screen contents and mouse/keyboard events to monitor the user's actions and the responses of the environment, while its effecters can generate such events for its own contributions to the interaction. We describe the architecture of our agent and * its algorithms for image processing, event management, and state representation. We illustrate the use of the agent with a small feasibility study in the area of software logging; results are promising for future progress.","Title: Toward Reducing Fault Fix Time: Understanding Developer Behavior for the Design of Automated Fault Detection Tools\nYear: 2007\n\nAbstract: The longer a fault remains in the code from the time it was injected, the more time it will take to fix the fault. Increasingly, automated fault detection (AFD) tools are providing developers with prompt feedback on recently-introduced faults to reduce fault fix time. If, however, the frequency and content of this feedback does not match the developer's goals and/or workflow, the developer may ignore the information. We conducted a controlled study with 18 developers to explore what factors are used by developers to decide whether or not to address a fault when notified of the error. The findings of our study lead to several conjectures about the design of AFD tools to effectively notify developers of faults in the coding phase. The AFD tools should present fault information that is relevant to the primary programming task with accurate and precise descriptions. The fault severity and the specific timing of fault notification should be customizable. Finally, the AFD tool must be accurate and reliable to build trust with the developer.","Title: Building Attack Scenarios through Integration of Complementary Alert Correlation Method\nYear: 2004\n\nAbstract: Several alert correlation methods were proposed in the past several years to construct high-level attack scenarios from low-level intrusion alerts reported by intrusion de-tection systems (IDSs). These correlation methods have different strengths and limitations; none of them clearly dominate the others. However, all of these methods de-pend heavily on the underlying IDSs, and perform poorly when the IDSs miss critical attacks. In order to improve the performance of intrusion alert correlation and reduce the impact of missed attacks, this paper presents a se-ries of techniques to integrate two complementary types of alert correlation methods: (1) those based on the sim-ilarity between alert attributes, and (2) those based on prerequisites and consequences of attacks. In particular, this paper presents techniques to hypothesize and reason about attacks possibly missed by IDSs based on the indi-rect causal relationship between intrusion alerts and the constraints they must satisfy. This paper also discusses additional techniques to validate the hypothesized attacks through raw audit data and to consolidate the hypothe-sized attacks to generate concise attack scenarios. The ex-perimental results in this paper demonstrate the potential of these techniques in building high-level attack scenarios and reasoning about possibly missed attacks.","Title: Prediction of web page accessibility based on structural and textual features\nYear: 2011\n\nAbstract: In this paper we present an approach to assessing the accessibility of Web pages, based on machine learning techniques. We are interested in the question of whether there are structural and textual features of Web pages, independent of explicit accessibility concerns, that nevertheless influence their usability for people with vision impairment. We describe three datasets, each containing a set of features corresponding to Web pages that are \"Accessible\" or \"Inaccessible\". Three classifiers are used to predict the category of these Web pages. Preliminary results are promising; they suggest the possibility of automated classification of Web pages with respect to accessibility.","Title: Experimental evaluation of intelligent assistance for navigation\nYear: 1998\n\nAbstract: Modern user interfaces make extensive use of navigation, a metaphor based on wayfinding in a physical space. Navigation can be an effective solution for many problems in understanding and manipulating a complex information space. Unfortunately, current research toward domain-independent, intelligent assistance for navigation lacks some important conceptual and practical tools for evaluation. This article describes an empirical study of assisted navigation that investigates the relationship between the quality of the assistance and overall performance. Our definition of quality is based on the information retrieval concepts of precision and recall. We use the limitations of the study results to motivate the development of a general-purpose navigation testbed. By separating the concerns of retrieving navigational data, maintaining and managing the resulting information space, and providing different views into the space, the testbed facilitates the development of navigational mechanisms and supports their evaluation. The testbed will act as a foundation for future work toward the automated generation of intelligent tools for navigational assistance.","Title: Two Algorithms for Inducing Structural Equation Models from Data\nYear: 1995\n\nAbstract: We present two algorithms for inducing structural equation models from data. Assuming no latent variables, these models have a causal interpretation and their parameters may be estimated by linear multiple regression. Our algorithms are comparable with PC and IC, which rely on conditional indepen- dence. We present the algorithms and empirical comparisons with PC and IC.","Title: A visual medium for programmatic control of interactive applications\nYear: 1999\n\nAbstract: The VisMap system provides for visual manipulation of arbitraryoff-the-shelf applications, through an applications graphical userinterface. VisMaps API-independent control has advantages for tasksthat can benefit from direct access to the functions of the userinterface. We describe the design goals and architecture of thesystem, and we discuss two applications, a user-controlled visualscripting program and an autonomous solitaire-playing program,which together demonstrate some of the capabilities and limitationsof the approach.","Title: Piagetian adaptation meets image schemas: the jean system\nYear: 2006\n\nAbstract: Jean is a model of early cognitive development based loosely on Piaget's theory of sensori-motor and pre-operational thought [1] Like an infant, Jean repeatedly executes schemas, gradually extending its schemas to accommodate new experiences Jean's environment is a simulated “playpen” in which Jean and other objects move about and interact Jean's cognitive development depends on several integrated functions: a simple perceptual system, an action-selection system, a motivational system, a long-term memory, and learning methods This paper provides an overview of Jean's architecture and schemas, and it focuses on how Jean learns schemas and transfers them to new situations.","Title: Model-based evaluation of expert cell phone menu interaction\nYear: 2007\n\nAbstract: We describe concepts to support the analysis of cell phone menu hierarchies, based on cognitive models of users and easy-to-use optimization techniques. We present an empirical study of user performance on five simple tasks of menu traversal on an example cell phone. Two of the models applied to these tasks, based on GOMS and ACT-R, give good predictions of behavior. We use the empirically supported models to create an effective evaluation and improvement process for menu hierarchies. Our work makes three main contributions: a novel and timely study of a new, very common HCI task; new versions of existing models for accurately predicting performance; and a search procedure to generate menu hierarchies that reduce traversal time, in simulation studies, by about a third.","Title: Pointing at responsive objects outdoors\nYear: 2012\n\nAbstract: In this paper we analyze pointing techniques for simple remote control of nearby and distant objects in an outdoor environment, using a mobile phone. In an experiment we determine the accuracy of pointing at targets from a few meters to a few hundred meters away, either by focusing the phone's camera on a target or holding the phone at waist level in the direction of the target. We describe a simulated network application in which users can activate and control one or more responsive objects using either interaction technique.","Title: Planning and user interface affordances\nYear: 1999\n\nAbstract: This paper takes a first step toward formalizing the conceptof affordance in user interfaces. Using a simple example ofan AI planning domain, we show how different types of affordancecan be described in terms of the costs associatedwith plan execution. We identify a number of similarities betweenexecuting plans and interacting with a graphical userinterface, and argue that affordances for planning environmentsapply equally well to user interface environments. Wesupport our argument with ...","Title: Computational modeling approaches help guide early design efforts for usability\nYear: 2009\n\nAbstract: In this paper, we describe the innovative approach of using formal computational models to guide design efforts and evaluate software interfaces for usability. Decades of work in the field of HCI looked to using task analyses, live user testing and GOMS modeling techniques to help design for usability. While these methods proved helpful, guidance came after the fact. Only after the prototype interface had been designed were the traditional techniques useful in evaluating the interface. This research seeks to be innovative in two ways. First, it seeks to examine techniques that can directly impact design at the very first stages where it is most critical. Second, it demonstrates the utility of a not so often used approach, that of using formal computational models to impact design. In this research, formal computational models were used to map sequences of operations of an activity or task. A candidate interface was then designed around the formal model's recommendations for what would be most facilitative for this activity. The result was an interface that performed optimally per model predictions. Additionally, live user testing was employed and empirical observations verified and reinforced the model predictions.","Title: Interface agents in model world environments\nYear: 2001\n\nAbstract: This article is concerned with systems that accommodateand exploit the properties of the graphical user interfaceas an environment. Many of these systems are interfaceagents, in the sense defined by Maes (Shneiderman andMaes 1997, p. 53): "An [interface] agent basically interactswith the application just like you interact with the application." Although nowadays the term "interface agent" encompassesall types of agents that interact with users, eventhose that depend not at all on the...","Title: MimEc: intelligent user notification of faults in the eclipse IDE\nYear: 2008\n\nAbstract: The earlier in the software process a fault is detected, the cheaper the cost of fixing the fault. Automated fault detection tools can provide developers with information throughout development, however, programming is a cognitively complex process and inundating the developer with information may do more harm than good. In this paper, we present MimEc, a part of the AWARE plug-in for the Eclipse integrated development environment. MimEc presents fault information to developers while they are writing code. The purpose of MimEc is to display only those faults in which a developer may be interested, thereby increasing the likelihood the developer will address the fault. MimEc infers interest in a fault based on fault criticality, relevance of the fault to the developer's current working context, and the developer's interactions with the programming environment. MimEc is currently under development and will be evaluated in both academic and professional settings.","Title: Navigation for Data Analysis Systems\nYear: 1997\n\nAbstract: . Statistical strategies are formal descriptions of the actionsand decisions involved in applying statistical tools to a problem. Onedifficult problem, beyond strategy design issues, is ensuring an effectiveinteraction between the the user and the implementation of the strategy.In this paper we review some existing techniques that have been effectivein mediating the interaction between users and expert statistical systemsfor data analysis. We explore the relationship between...","Title: Toward automated exploration of interactive systems\nYear: 2002\n\nAbstract: The ease with which a user interface can be navigated strongly contributes to its usability. In this paper we describe preliminary results of a project aimed at making the evaluation of user interfaces from this perspective more routine. We have designed a system to carry out an autonomous, exploratory navigation through the graphical user interface of interactive, off-the-shelf software applications. The system is not a robust tool, but rather a proof of concept that can exhibit interesting behaviors. The traversal process generates a representation of the connectivity of the user interface, as well as navigational paths to specific commands. The reasoning component of the system is based on the ACT-R architecture, while the perceptual and motor components of the system are built on top of the SegMan perception/action substrate. We present the design of the system and its use in exploring a simple user interface.","Title: Visual generalization in programming by example\nYear: 2000\n\nAbstract: In Programming by Example, the system records actions performed by a user in the interface, and produces a generalized program that can be used later in analogous examples. A key issue is how to describe the actions and objects selected by the user, which determines what kind of generalizations will be possible. When the user selects graphical objects on the screen, most PBE systems describe those objects using properties of the application data that the visual objects represent. For example, if the user selects a text label inside a box in a calendar program, the PBE system might represent that as selecting a particular appointment. In this article, we explore a different, and radical, approach -- using visual properties of the interaction elements themselves, such as size, shape, color, and appearance of graphical objects -- to describe user intentions. Only recently has the speed of image processing made feasible real-time analysis of screen images by a PBE system. We believe that this approach opens up some unique advantages. Foremost among them is that PBE systems can work from the visual appearance of applications, and do not need explicit cooperation from the application's API, thereby removing one of the worst stumbling-blocks preventing the use of PBE with commercial applications. Visually- oriented systems stick more closely to what the user can actually see, and so should be more transparent, especially for beginning users. Finally, they open up the possibility of new kinds of generalizations not anticipated by application designers or not possible from the application data alone.","Title: Visual Perception and Mixed-Initiative Interaction for Assisted Visualization Design\nYear: 2008\n\nAbstract: This paper describes the integration of perceptual guidelines from human vision with an AI-based mixed-initiative search strategy. The result is a visualization assistant called ViA, a system that collaborates with its users to identify perceptually salient visualizations for large, multidimensional datasets. ViA applies knowledge of low-level human vision to: (1) evaluate the effectiveness of a particular visualization for a given dataset and analysis tasks; and (2) rapidly direct its search towards new visualizations that are most likely to offer improvements over those seen to date. Context, domain expertise, and a high-level understanding of a dataset are critical to identifying effective visualizations. We apply a mixed-initiative strategy that allows ViA and its users to share their different strengths and continually improve ViA's understanding of a user's preferences. We visualize historical weather conditions to compare ViA's search strategy to exhaustive analysis, simulated annealing, and reactive tabu search, and to measure the improvement provided by mixed-initiative interaction. We also visualize intelligent agents competing in a simulated online auction to evaluate ViA's perceptual guidelines. Results from each study are positive, suggesting that ViA can construct high-quality visualizations for a range of real-world datasets.","Title: User interface affordances in a planning representation\nYear: 1999\n\nAbstract: This article shows how the concept of affordance in the user interface fits into a well-understood artificial intelligence (AI) model of acting in an environment. In this model AI planning research is used to interpret affordances in terms of the costs associated with the generation and execution of operators in a plan. This article motivates the approach with a brief survey of the affordance literature and its connections to the planning literature and then explores its implications through examples of common user interface mechanisms described in affordances terms. Despite its simplicity, the modeling approach ties together several different threads of practical and theoretical work on affordance into a single conceptual framework.","Title: CAPTIVE: a cube with augmented physical tools\nYear: 2014\n\nAbstract: This paper describes a tangible 3D user interface called CAPTIVE, a Cube with Augmented Physical Tools, for exploration of 3D information. The design of CAPTIVE is founded on the concept of tool use, in which handheld tool objects are used to modify the properties or appearance of target objects. The user of CAPTIVE holds a physical wireframe cube that contains virtual objects in one hand, in the other a pointing device, its tip visually augmented to reflect its function as a tool. On the display the user watches the immediate, direct effects of actions with the tool. In the current prototype, routines for handling cube manipulation and an augmented haptic pointing device have been separately implemented, but integration and refinement remain to be done. In this paper we describe our vision of the system and preliminary testing carried out to date.","Title: A visual interface to a music database\nYear: 2002\n\nAbstract: This paper describes a system for exploring and selecting entries from a music database through a visualization interface. The system is designed for deployment in situations in which the user's attention is a tightly limited resource. The system combines research topics in intelligent user interfaces, visualization techniques, and cognitive modeling. Informal evaluation of the system has given us useful insights into the design tradeoffs that developers may face when building visual interfaces for off-the-desktop applications.","Title: Specifying ACT-R models of user interaction with a GOMS language\nYear: 2005\n\nAbstract: We describe a system, G2A, that produces ACT-R models from GOMS models. The GOMS models can contain hierarchical methods, visual and memory stores, and control constructs. G2A allows ACT-R models to be built much more quickly, in hours rather than weeks. Because GOMS is a more abstract formalism than ACT-R, most GOMS operators can be plausibly translated in different ways into ACT-R productions (e.g., a GOMS Look-for operator can be carried out by different visual search strategies in ACT-R). Given a GOMS model, G2A generates and evaluates alternative ACT-R models by systematically varying the mapping of GOMS operators to ACT-R productions. In experiments with a text editing task, G2A produces ACT-R models whose predictions are within 5% of GOMS model predictions. In the same domain, G2A also generates ACT-R models that give better predictions than GOMS, providing good predictions of overall task duration for actual users (within 2%), though the models are less accurate at a detailed level. In a separate experiment with a mouse-driven telephone dialing task, G2A produces models that do a better job of distinguishing between competing interfaces than a Fitts' law model or an ACT-R model built by hand. G2A starts to describe the relationship between two major theories of cognition. This may have appeared a simple relationship, but the complexity of the translation illustrates why this was not done before. G2A shows a way forward for cognitive models, that of higher level languages that compile into more detailed specifications.","Title: Evaluation of a semi-autonomous assistant for exploratory data analysis\nYear: 1997\n\nAbstract: Aide is a knowledge-based planning assistant for intelligentdata exploration that draws on research inmixed-initiative planning and collaborative systems.Aide incrementally explores a dataset, guided by userdirectives and its own evaluation of the data. The systemis mixed-initiative: it semi-autonomously pursueshigh- and low-level goals but allows the user to reviewand potentially override its decisions. This paperbriefly describes the exploratory task, Aide's architecture,and how the ...","Title: Assisted visualization of e-commerce auction agents\nYear: 2001\n\nAbstract: This paper describes the integration of perceptual guidelines from human vision with an Al-based mixed-initiative search technique. The result is a visualization assistant, a system that identifies perceptually salient visualizations for large, multidimensional collections of data. Understanding how the low-level human visual system \"sees\" visual information in an image allows us to: (1) evaluate a particular visualization, and (2) direct the search algorithm towards new visualizations that may be better than those seen to date. In this way we can limit search to locations that have the highest potential to contain effective visualizations. One testbed application for this work is the visualization of intelligent e-commerce auction agents participating in a simulated online auction environment. We describe how the visualization assistant was used to choose methods to effectively visualize this data.","Title: Tool use for autonomous agents\nYear: 2005\n\nAbstract: The intelligent use of tools is a general and important human competence that AI research has not yet examined in depth. Other fields have studied the topic, however, with results we can compile into a broad characterization of habile (tool-using) agents. In this paper we give an overview of research on the use of physical tools, using this information to motivate the development of artificial habile agents. Specifically, we describe how research goals and methods in animal cognition overlap with those in artificial intelligence. We argue that analysis of activities of tool-using agents offers an informative way to evaluate intelligence.","Title: Interaction with a mixed-initiative system for exploratory data analysis\nYear: 1998\n\nAbstract: Exploratory data analysis (EDA) plays an increasinglyimportant role in statistical analysis. EDA is difficult,however, even with the help of modern statistical software.We have developed an assistant for data exploration,based on AI planning techniques, that addressessome of the strategic shortcomings of conventional software.This paper illustrates the behavior of the system,gives a high level description of its design, and discussesits experimental evaluation.KeywordsArtificial...","Title: Links: AI planning resources on the Web\nYear: 2001\n\nAbstract: With the introduction of new, efficient techniques for planning, interest in the field has risen sharply in recent years. Planning systems have come a long way since the days of Blocks World. Today, planning and scheduling techniques are being used to solve problems in military campaign planning, robot navigation, industrial equipment scheduling, human-computer interaction, and many other real-world domains. Planning, which is the process of finding a sequence of actions that meets an agents goal, is a thriving area of artificial intelligence (AI) research and is growing almost faster than one can keep track. Fortunately, an abundance of information about planning is available, in both paper and electronic forms; answers to most of the questions a newcomer to the field might ask can easily be found. What is planning?","Title: Model-based evaluation of cell phone menu interaction\nYear: 2004\n\nAbstract: Cell phone interfaces are now ubiquitous. In this paper, we describe concepts to support the analysis of cell phone menu hierarchies. We present an empirical study of user performance on five simple tasks of menu traversal on a cell phone. Two models we tested, based on GOMS and ACT-R, give very good predictions of behavior. We use the study results to motivate an effective evaluation process for menu hierarchies. Our work makes several contributions: a novel and timely study of a new, very common HCI task; new models for accurately predicting performance; novel development tools to support such modeling; and a search procedure to generate menu hierarchies that reduce traversal time, in simulation studies, by about a third.","Title: Intelligent visualization in a planning simulation\nYear: 2001\n\nAbstract: This paper describes a set of visualization techniques for interactive planning in a physical force simulation called AFS. We have developed a 3D environment in which textures are overlaid on a simulated landscape to convey information about environmental properties, agent actions, and possible strategies. Scenes are presented, via automated camera planning, such that some simple agent goals can be induced visually with little effort. These two areas of visualization functionality in AFS exploit properties of human low-level and intermediate-level vision, respectively. This paper presents AFS, its visualization environment, and studies we have run to explore the relationship between AFS visualizations and the high-level planning process.","Title: Social navigation: modeling, simulation, and experimentation\nYear: 2003\n\nAbstract: The term social navigation refers to the process of seeking social interaction as a source of navigational support. In this paper we present a computational model of social navigation as an extension to an existing conceptual, non-computational model of general navigation. We argue that such models are important in designing effective shared environments for information navigation. We describe support for the model with a simulation environment for social navigation and an analytical model that addresses some of the quantitative implications of social interaction on the process.","Title: Balancing efficiency and interpretability in an interactive statistical assistant\nYear: 2003\n\nAbstract: Making an interface more efficient, in a task analysis sense, can make it more difficult for an automated reasoning system to infer user goals, by eliminating some user actions, by presenting information without requiring overt user selection, and so forth. We call the extent to which a system can make such inferences interpretability. In this paper we describe the tradeoff between interpretability and efficiency. We give some general heuristics for improving interpretability in a system and explain how they apply in an implemented system, an assistant for exploratory statistical analysis. Increased interpretability in the system is provided by navigation techniques for data exploration and a data mountain for organizing results; a formative evaluation illustrates some of the potential benefits of applying interpretability heuristics to an intelligent user interface","Title: CAVIAR: a vibrotactile device for accessible reaching\nYear: 2012\n\nAbstract: CAVIAR is designed to aid people with vision impairment in locating, identifying, and acquiring objects in their peripersonal space. A mobile phone, worn on the chest, captures video in front of the user; the computer vision component locates the user's hand and objects in the video stream. The auditory component informs the user about the presence of objects. On user confirmation, the reaching component sends signals to vibrotactile actuators on the user's wristband, guiding the hand to a specific object. This paper describes an end-to-end prototype of CAVIAR and its formative evaluation.","Title: Novice use of a predictive human performance modeling tool to produce UI recommendations\nYear: 2014\n\nAbstract: This note describes two studies of the use of a performance modeling tool, CogTool, for making recommendations to improve a user interface. The first study replicates findings by Bonnie John [7]: the rates at which novice modelers made correct recommendations (88.1%) and supported them (68.2%) are close to the values in John's study (91.7% and 75.1%, respectively). A follow-on study of novice modelers on the same task without CogTool produced sig-nificantly lower values. CogTool improves the UI design recommendations made by novices.","Title: Links: artificial intelligence and interactive entertainment\nYear: 2001\n\nAbstract: As John Laird pointed out in his IAAI/AAAI invited talk last year, artificial intelligence research and computer gaming have quite a bit to offer one another. While many of the most commercially successful computer games have been rather visceral and violent in nature, AI techniques offer the promise of creating engaging and dynamic interactive entertainment with strong narrative components. The research challenges posed for AI researchers when addressing their work in the context of computers games are as complex and compelling as many \"actual-world\" problem areas and the context of gaming environments offers up unique interfaces, modes of use and an extensive existing base of potential users. In this article, we'll introduce some of the aspects of the application of artificial intelligence research in the context of interactive entertainment. While intelligent techniques are certainly applicable to a wide range of computer games, here we'll focus primarily on games that simulate or create highly interactive virtual environments - games where one or more users control various aspects of the game's world, either in discrete steps (i.e, turn-taking) or in continuous real-time modes.","Title: A tool-based interactive drawing environment\nYear: 2002\n\nAbstract: Graphical user interfaces rely heavily on the tool metaphor. In most drawing systems, for example, functions are organized as they might be on a workbench; buttons associated with drawing modes for lines or rectangles are called line-drawing or rectangle-drawing tools; etc. Despite the similarities, however, there remain many differences between software tools and physical tools. This paper gives a concise account of tool use in general, and describes a drawing application, called HabilisDraw, that relies on a detailed correspondence to physical tool behavior.","Title: AI support for building cognitive models\nYear: 2006\n\nAbstract: Cognitive modeling techniques provide a way of evaluating user interface designs, based on what is known about human cognitive strengths and limitations. Cognitive modelers face a tradeoff, however: more detailed models require disproportionately more time and effort to develop than coarser models. In this paper we describe a system, G2A, that automatically produces translations from abstract GOMS models into more detailed ACT-R models. G2A demonstrates how even simple AI techniques can facilitate the construction of cognitive models and suggests new directions for improving modeling tools.","Title: Search for efficient device-dependent action sequences in the user interface\nYear: 2003\n\nAbstract: This paper describes a design tool, under development, that identifies efficient low-level action sequences in the user interface, accounting for the relationships between the physical properties of an input device and the requirements of primitive tasks. A device representation and a task taxonomy are presented. These, along with a library of efficiency measures for specific devices, provide information to steer search through the space of action sequences.","Title: A reduced QWERTY keyboard for mobile text entry\nYear: 2004\n\nAbstract: In this paper we describe a specialized keyboard for text entry that maps four rows of a standard keyboard onto the home row, with different characters encoded via modifier keys and multi-tap input. Use of the keyboard also relies on lexicon-based disambiguation. This design has two motivations: limiting physical space requirements and capitalizing on user knowledge of the standard QWERTY keyboard layout. The resulting \"stick\" keyboard is between 15% and 25% of the size of a standard keyboard. In a preliminary empirical study, users reached half of their normal typing speed using lexicon-based disambiguation (22.5 wpm) and a reasonable but lower speed with multi-tap input (10.4 wpm) with only a few minutes of practice.","Title: Toward the Integration of Exploration and Modeling in a Planning Framework\nYear: 1994\n\nAbstract: Statistical operations are often facilitated by other operations. We can facilitate modeling operations by testing their input for irregularities and removing problems wherever possible. A planning representation is well-suited to this task. We describe the representation used in Igor, a system for exploratory data analysis, and its integration with two modeling systems, Pearl''s IC and Cohen''s FBD. We show that introducing outliers into the inputs of the algorithms can influence their performance. We demonstrate that a planning representation offers a flexible way of integrating outlier detection and removal into the modeling process, taking account of specific characteristics of the modeling operations involved.","Title: Power tools and composite tools: integrating automation with direct manipulation\nYear: 2003\n\nAbstract: This paper describes a drawing system that incorporates two novel interaction techniques based on analogies to physical tools. Power tools add limited autonomy in the form of rotators and movers for automated circular, linear, and Bezier-curve movement. Composite tools are user-constructed combinations of existing tools to create new functionality.","Title: Detecting abnormal user behavior through pattern-mining input device analytics\nYear: 2015\n\nAbstract: This paper presents a method for detecting patterns in the usage of a computer mouse that can give insights into user's cognitive processes. We conducted a study using a computer version of the Memory game (also known as the Concentration game) that allowed some participants to reveal the content of the tiles, expecting their low-level mouse interaction patterns to deviate from those of normal players with no access to this information. We then trained models to detect these differences using task-independent input device features. The models detected cheating with 98.73% accuracy for players who cheated or did not cheat consistently for entire rounds of the game, and with 89.18% accuracy for cases in which players enabled and then disabled cheating within rounds.","Title: Exploring key-level analytics for computational modeling of typing behavior\nYear: 2014\n\nAbstract: Typing is a human activity that can be affected by a number of situational and task-specific factors. Changes in typing behavior resulting from the manipulation of such factors can be predictably observed through key-level input analytics. Here we present a study designed to explore these relationships. Participants play a typing game in which letter composition, word length and number of words appearing together are varied across levels. Inter-keystroke timings and other higher order statistics (such as bursts and pauses), as well as typing strategies, are analyzed from game logs to find the best set of metrics that quantify the effect that different experimental factors have on observable metrics. Beyond task-specific factors, we also study the effects of habituation by recording changes in performance with practice. Currently a work in progress, this research aims at developing a predictive model of human typing. We believe this insight can lead to the development of novel security proofs for interactive systems that can be deployed on existing infrastructure with minimal overhead. Possible applications of such predictive capabilities include anomalous behavior detection, authentication using typing signatures, bot detection using word challenges etc.","Title: Integrating statistical methods for characterizing causal influences on planner behavior over time\nYear: 1994\n\nAbstract: Statistical causal modeling techniques allow us to develop models of program behavior, but these techniques tend to be limited in what they can model: either continuing, repetitive influences or causal influences without cycles, but not both as appear in many environments. The paper describes how two statistical modeling techniques can be combined to suggest and test specific hypotheses about how the environment and the AI planner's design causally influence the planner's behavior. One technique, dependency detection, is designed to identify relationships (dependencies) between particular failures, the methods that repair them and the occurrence of failures downstream. Another method, path analysis, builds causal models of correlational data. Dependency detection operates over a series of events, and path analysis models within a temporal snapshot. We explain the integration of the techniques and demonstrate it on execution data from the Phoenix planner","Title: A Partial Contour Similarity-Based Approach to Visual Affordances in Habile Agents\nYear: 2017\n\nAbstract: In a typical tool use task, we can view both the relationship between the agent and the tool and the relationship between the tool and the target in terms of affordances. One set of affordances relates to the ability of the agent to manipulate the tool, while a second set of affordances relates to the ability of the agent to manipulate the target by means of the tool. In both cases, effective tool...","Title: Natural Interaction with Visualization Systems\nYear: 2015\n\nAbstract: As new input devices and interaction techniques emerge daily, how might they improve interactive visualization?","Title: Control Representation in an EDA Assistant\nYear: 1995\n\nAbstract: To develop an initial understanding of complex data, one often begins with exploration. Exploratory data analysis (EDA) provides a set of statistical tools through which patterns in data may be extracted and examined in detail. The search space of EDA operations is enormous, too large to be explored directly in a data-driven manner. More abstract EDA procedures can be captured, however, by representations commonly used in AI planning systems. We describe an implemented planning representation for \\aide/, an automated EDA assistant, with a focus on control issues.","Title: Natural Interaction for Bot Detection.\nYear: 2016\n\nAbstract: Bot detection - identifying a software program that's using a computer system -- is an increasingly necessary security task. Existing solutions balance proof of human identity with unobtrusiveness in users' workflows. Cognitive modeling and natural interaction might provide stronger security and less intrusiveness.","Title: Human Subtlety Proofs: Using Computer Games To Model Cognitive Processes For Cybersecurity\nYear: 2017\n\nAbstract: This article describes an emerging direction in the intersection between human-computer interaction and cognitive science: the use of cognitive models to give insight into the challenges of cybersecurity (cyber-SA). The article gives a brief overview of work in different areas of cyber-SA where cognitive modeling research plays a role, with regard to direct interaction between end users and computer systems and with regard to the needs of security analysts working behind the scenes. The problem of distinguishing between human users and automated agents (bots) interacting with computer systems is introduced, as well as ongoing efforts toward building Human Subtlety Proofs (HSPs), persistent and unobtrusive windows into human cognition with direct application to cyber-SA. Two computer games are described, proxies to illustrate different ways in which cognitive modeling can potentially contribute to the development of HSPs and similar cyber-SA applications.","Title: Usability guidelines for interactive search in direct manipulation systems\nYear: 2001\n\nAbstract: Extracting rules from RBFs is not a trivial task because of nonlinear functions or high input dimensionality. In such cases, some of the hidden units of the RBF network have a tendency to be \"shared\" across several output classes or even may not contribute ...","Title: Performance Characteristics of a Camera-Based Tangible Input Device for Manipulation of 3D Information.\nYear: 2017\n\nAbstract: This paper describes a prototype tangible six degree of freedom (6 DoF) input device that is inexpensive and intuitive to use: a cube with colored corners of specific shapes, tracked by a single camera, with pose estimated in real time. A tracking and automatic color adjustment system are designed so that the device can work robustly with noisy surroundings and is invariant to changes in lighting and background noise. A system evaluation shows good performance for both refresh (above 60 FPS on average) and accuracy of pose estimation (average angular error of about 1). A user study of 3D rotation tasks shows that the device outperforms other 6 DoF input devices used in a similar desktop environment. The device has the potential to facilitate interactive applications such as games as well as viewing 3D information.","Title: Spoken language interaction with robots: Recommendations for future research\nYear: 2022\n\nAbstract: With robotics rapidly advancing, more effective human-robot interaction is increasingly needed to realize the full potential of robots for society. While spoken language must be part of the solution, our ability to provide spoken language interaction capabilities is still very limited. In this article, based on the report of an interdisciplinary workshop convened by the National Science Foundation, we identify key scientific and engineering advances needed to enable effective spoken language interaction with robotics. We make 25 recommendations, involving eight general themes: putting human needs first, better modeling the social and interactive aspects of language, improving robustness, creating new methods for rapid adaptation, better integrating speech and language with other communication modalities, giving speech and language components access to rich representations of the robot's current knowledge and state, making all components operate in real time, and improving research infrastructure and resources. Research and development that prioritizes these topics will, we believe, provide a solid foundation for the creation of speech-capable robots that are easy and effective for humans to work with."],"string":"[\n \"Title: User Interface Softbots\\nYear: 2000\\n\\nAbstract: s, effectors, and controller providea general-purpose means of managing interactive applications,through the same medium as a real user.System componentsConceptually, we can break down ibot functionality intothree components, as we might do with any physically realizedrobot: perception, action, and control.PerceptionIbot perception relies on conventional image processingtechniques. Object identification follows a three-stage processof segmentation, feature computation, and...\",\n \"Title: A planner for exploratory data analysis\\nYear: 1996\\n\\nAbstract: Statistical exploratory data analysis (EDA) poses a difficult search problem. The EDA process lends itself however to a planning for- mulation. We have built a system, called AIDE, to help users explore data. Atl)F~ re- lies or, partial hierarchical planning, a form of planning appropriate for tasks in complex. uncertain environments. Our description of the EDA task and the AIDE system provides a case study of the applicat ion of plamdng to a novel domain.\",\n \"Title: Navigation and planning in a mixed-initiative user interface\\nYear: 1997\\n\\nAbstract: Mixed-initiative planning is one approach to building an intelligent decision-making environment. A mixed-initiative system shares decision-making responsibility with the user such that it acts sometimes as a tool, to be directly applied to a specific task, and other times as an autonomous problem-solver. In the best case, the user can delegate the details of a task to the automated system without giving up the ability to guide and review the decision-making process. We have developed a simple mixed-initiative planner that incorporates a view of problem-solving as navigation. We have explored this notion in two different applications: exploratory statistical analysis and layout design for user interface dialogs. This paper discusses navigation issues in the context of these two systems, the potential benefits of the approach, and some implications for user interface design.\",\n \"Title: Environment modification in a simulated human-robot interaction task:: experimentation and analysis\\nYear: 2003\\n\\nAbstract: This paper describes a novel approach to human-robot interaction, in which a user modifies a robot's environment to constrain its actions, rather than programming its controller. An HRI simulation of a maze navigation task is presented. An empirical evaluation shows that for this task, users prefer an environment modification strategy rather than a programming strategy as the difficulty of the task increases. Further, user alternation between the two types of strategy follows a clear pattern. A preliminary model extending the HRI simulation, one which allows the specification of more general navigation environments, is also presented\",\n \"Title: The user interface as an agent environment\\nYear: 2000\\n\\nAbstract: Mainstream planning systems make a number of assump- tions about their environments, in areas such as the pre- dictability of action effects, accessibility to state informa- tion, and static behavior of the environment. We find a striking correspondence between these assumptions and the properties of graphical user interfaces. We have developed a novel type of interface agent, called an ibot, to exploit these correspondences. Ibots can interact with off-the-shelf appli- cations through the user interface rather than programmati- cally, gaining access to functionality not readily available to artificial agents by other means. In this paper we describe the relationship between these agents and the theoretical and heuristic properties of user interfaces. We demonstrate the feasibility of our approach to interface agents with an imple- mented prototype that interacts with an unmodified applica- tion for graphical illustration.\",\n \"Title: A glove for tapping and discrete 1D/2D input\\nYear: 2012\\n\\nAbstract: This paper describes a glove with which users enter input by tapping fingertips with the thumb or by rubbing the thumb over the palmar surfaces of the middle and index fingers. The glove has been informally tested as the controller for two semi-autonomous robots in a a 3D simulation environment. A preliminary evaluation of the glove's performance is presented.\",\n \"Title: An environment for user interface softbots\\nYear: 2002\\n\\nAbstract: A user interface softbot is a software agent that controls an interactive system through the graphical user interface, relying on visual information from the system rather than an application programming interface or access to source code. Interface softbots have acted as autonomous agents in applications such as drawing and data recording, and the core vision processing algorithms have been incorporated into cognitive models for simple problem-solving tasks. Building interface softbots is still a time-consuming task, unfortunately, requiring experience with complex program components as well as the details of the visual interface. We have developed a prototype development environment that facilitates the development of interface softbots, streamlining the programming process and making it more accessible to new developers.\",\n \"Title: An experiment with navigation and intelligent assistance\\nYear: 1998\\n\\nAbstract: Modern user interfaces make extensive use of navigation, a metaphor based on wayfinding in a physical space. Navigation can be an effective solution for many problems in understanding and manipulating a complex information space. Our work is in the area of intelligent assistance for decision support environments, where assistance may take the form of automatically exploring decision alternatives, recording justifications for actions, testing global consistency of local results, and generating audit trails, among other activities. This paper describes an experimental evaluation of assisted search in an artificial environment using navigation as a communication medium, under conditions that vary the quality of assistance.\",\n \"Title: A User Modeling Design Tool Based on a Cognitive Architecture for Comparing Interfaces\\nYear: 2002\\n\\nAbstract: Usability evaluation has long been recognized as an indispensable part of the development of interactive software. Evaluation can still be a difficult and labor- intensive task with conventional tools and user studies, however. Results can vary with the knowledge and experience of the evaluator and with the subjects. We describe an approach to evaluation, based on cognitive modeling, that will alleviate some of these problems. We are building a general-purpose, cross- platform architecture in which user performance in an interactive environment is simulated by a cognitive model. The results of the model can be analyzed and fed back into the development lifecycle. This project is still preliminary, but progress is accelerating.\",\n \"Title: Introductory AI educational resources on the web\\nYear: 2001\\n\\nAbstract: Fortunately for people seeking to learn more about artificial intelligence, a wide range of general and introductory educational materials related to AI is available on the Web. The Web resources described below, available both in electronic form and as pointers to conventional media such as books or videos, are not, however, of interest just to university educators and their students. Many of them are of broad scope and are useful to information technology specialists or AI practitioners seeking a starting-off point from which to improve their knowledge of the field. Some of the materials listed here will also be of use to educators in high schools or middle schools where AI topics may play a role in course curricula.\",\n \"Title: IBOTS: agent control through the user interface\\nYear: 1999\\n\\nAbstract: This paper describes an ibot, a specialized software agent that exists in the environment of the user interface. Such an agent interacts with applications through the same medium as a human user. Its sensors process screen contents and mouse/keyboard events to monitor the user's actions and the responses of the environment, while its effecters can generate such events for its own contributions to the interaction. We describe the architecture of our agent and * its algorithms for image processing, event management, and state representation. We illustrate the use of the agent with a small feasibility study in the area of software logging; results are promising for future progress.\",\n \"Title: Toward Reducing Fault Fix Time: Understanding Developer Behavior for the Design of Automated Fault Detection Tools\\nYear: 2007\\n\\nAbstract: The longer a fault remains in the code from the time it was injected, the more time it will take to fix the fault. Increasingly, automated fault detection (AFD) tools are providing developers with prompt feedback on recently-introduced faults to reduce fault fix time. If, however, the frequency and content of this feedback does not match the developer's goals and/or workflow, the developer may ignore the information. We conducted a controlled study with 18 developers to explore what factors are used by developers to decide whether or not to address a fault when notified of the error. The findings of our study lead to several conjectures about the design of AFD tools to effectively notify developers of faults in the coding phase. The AFD tools should present fault information that is relevant to the primary programming task with accurate and precise descriptions. The fault severity and the specific timing of fault notification should be customizable. Finally, the AFD tool must be accurate and reliable to build trust with the developer.\",\n \"Title: Building Attack Scenarios through Integration of Complementary Alert Correlation Method\\nYear: 2004\\n\\nAbstract: Several alert correlation methods were proposed in the past several years to construct high-level attack scenarios from low-level intrusion alerts reported by intrusion de-tection systems (IDSs). These correlation methods have different strengths and limitations; none of them clearly dominate the others. However, all of these methods de-pend heavily on the underlying IDSs, and perform poorly when the IDSs miss critical attacks. In order to improve the performance of intrusion alert correlation and reduce the impact of missed attacks, this paper presents a se-ries of techniques to integrate two complementary types of alert correlation methods: (1) those based on the sim-ilarity between alert attributes, and (2) those based on prerequisites and consequences of attacks. In particular, this paper presents techniques to hypothesize and reason about attacks possibly missed by IDSs based on the indi-rect causal relationship between intrusion alerts and the constraints they must satisfy. This paper also discusses additional techniques to validate the hypothesized attacks through raw audit data and to consolidate the hypothe-sized attacks to generate concise attack scenarios. The ex-perimental results in this paper demonstrate the potential of these techniques in building high-level attack scenarios and reasoning about possibly missed attacks.\",\n \"Title: Prediction of web page accessibility based on structural and textual features\\nYear: 2011\\n\\nAbstract: In this paper we present an approach to assessing the accessibility of Web pages, based on machine learning techniques. We are interested in the question of whether there are structural and textual features of Web pages, independent of explicit accessibility concerns, that nevertheless influence their usability for people with vision impairment. We describe three datasets, each containing a set of features corresponding to Web pages that are \\\"Accessible\\\" or \\\"Inaccessible\\\". Three classifiers are used to predict the category of these Web pages. Preliminary results are promising; they suggest the possibility of automated classification of Web pages with respect to accessibility.\",\n \"Title: Experimental evaluation of intelligent assistance for navigation\\nYear: 1998\\n\\nAbstract: Modern user interfaces make extensive use of navigation, a metaphor based on wayfinding in a physical space. Navigation can be an effective solution for many problems in understanding and manipulating a complex information space. Unfortunately, current research toward domain-independent, intelligent assistance for navigation lacks some important conceptual and practical tools for evaluation. This article describes an empirical study of assisted navigation that investigates the relationship between the quality of the assistance and overall performance. Our definition of quality is based on the information retrieval concepts of precision and recall. We use the limitations of the study results to motivate the development of a general-purpose navigation testbed. By separating the concerns of retrieving navigational data, maintaining and managing the resulting information space, and providing different views into the space, the testbed facilitates the development of navigational mechanisms and supports their evaluation. The testbed will act as a foundation for future work toward the automated generation of intelligent tools for navigational assistance.\",\n \"Title: Two Algorithms for Inducing Structural Equation Models from Data\\nYear: 1995\\n\\nAbstract: We present two algorithms for inducing structural equation models from data. Assuming no latent variables, these models have a causal interpretation and their parameters may be estimated by linear multiple regression. Our algorithms are comparable with PC and IC, which rely on conditional indepen- dence. We present the algorithms and empirical comparisons with PC and IC.\",\n \"Title: A visual medium for programmatic control of interactive applications\\nYear: 1999\\n\\nAbstract: The VisMap system provides for visual manipulation of arbitraryoff-the-shelf applications, through an applications graphical userinterface. VisMaps API-independent control has advantages for tasksthat can benefit from direct access to the functions of the userinterface. We describe the design goals and architecture of thesystem, and we discuss two applications, a user-controlled visualscripting program and an autonomous solitaire-playing program,which together demonstrate some of the capabilities and limitationsof the approach.\",\n \"Title: Piagetian adaptation meets image schemas: the jean system\\nYear: 2006\\n\\nAbstract: Jean is a model of early cognitive development based loosely on Piaget's theory of sensori-motor and pre-operational thought [1] Like an infant, Jean repeatedly executes schemas, gradually extending its schemas to accommodate new experiences Jean's environment is a simulated “playpen” in which Jean and other objects move about and interact Jean's cognitive development depends on several integrated functions: a simple perceptual system, an action-selection system, a motivational system, a long-term memory, and learning methods This paper provides an overview of Jean's architecture and schemas, and it focuses on how Jean learns schemas and transfers them to new situations.\",\n \"Title: Model-based evaluation of expert cell phone menu interaction\\nYear: 2007\\n\\nAbstract: We describe concepts to support the analysis of cell phone menu hierarchies, based on cognitive models of users and easy-to-use optimization techniques. We present an empirical study of user performance on five simple tasks of menu traversal on an example cell phone. Two of the models applied to these tasks, based on GOMS and ACT-R, give good predictions of behavior. We use the empirically supported models to create an effective evaluation and improvement process for menu hierarchies. Our work makes three main contributions: a novel and timely study of a new, very common HCI task; new versions of existing models for accurately predicting performance; and a search procedure to generate menu hierarchies that reduce traversal time, in simulation studies, by about a third.\",\n \"Title: Pointing at responsive objects outdoors\\nYear: 2012\\n\\nAbstract: In this paper we analyze pointing techniques for simple remote control of nearby and distant objects in an outdoor environment, using a mobile phone. In an experiment we determine the accuracy of pointing at targets from a few meters to a few hundred meters away, either by focusing the phone's camera on a target or holding the phone at waist level in the direction of the target. We describe a simulated network application in which users can activate and control one or more responsive objects using either interaction technique.\",\n \"Title: Planning and user interface affordances\\nYear: 1999\\n\\nAbstract: This paper takes a first step toward formalizing the conceptof affordance in user interfaces. Using a simple example ofan AI planning domain, we show how different types of affordancecan be described in terms of the costs associatedwith plan execution. We identify a number of similarities betweenexecuting plans and interacting with a graphical userinterface, and argue that affordances for planning environmentsapply equally well to user interface environments. Wesupport our argument with ...\",\n \"Title: Computational modeling approaches help guide early design efforts for usability\\nYear: 2009\\n\\nAbstract: In this paper, we describe the innovative approach of using formal computational models to guide design efforts and evaluate software interfaces for usability. Decades of work in the field of HCI looked to using task analyses, live user testing and GOMS modeling techniques to help design for usability. While these methods proved helpful, guidance came after the fact. Only after the prototype interface had been designed were the traditional techniques useful in evaluating the interface. This research seeks to be innovative in two ways. First, it seeks to examine techniques that can directly impact design at the very first stages where it is most critical. Second, it demonstrates the utility of a not so often used approach, that of using formal computational models to impact design. In this research, formal computational models were used to map sequences of operations of an activity or task. A candidate interface was then designed around the formal model's recommendations for what would be most facilitative for this activity. The result was an interface that performed optimally per model predictions. Additionally, live user testing was employed and empirical observations verified and reinforced the model predictions.\",\n \"Title: Interface agents in model world environments\\nYear: 2001\\n\\nAbstract: This article is concerned with systems that accommodateand exploit the properties of the graphical user interfaceas an environment. Many of these systems are interfaceagents, in the sense defined by Maes (Shneiderman andMaes 1997, p. 53): "An [interface] agent basically interactswith the application just like you interact with the application." Although nowadays the term "interface agent" encompassesall types of agents that interact with users, eventhose that depend not at all on the...\",\n \"Title: MimEc: intelligent user notification of faults in the eclipse IDE\\nYear: 2008\\n\\nAbstract: The earlier in the software process a fault is detected, the cheaper the cost of fixing the fault. Automated fault detection tools can provide developers with information throughout development, however, programming is a cognitively complex process and inundating the developer with information may do more harm than good. In this paper, we present MimEc, a part of the AWARE plug-in for the Eclipse integrated development environment. MimEc presents fault information to developers while they are writing code. The purpose of MimEc is to display only those faults in which a developer may be interested, thereby increasing the likelihood the developer will address the fault. MimEc infers interest in a fault based on fault criticality, relevance of the fault to the developer's current working context, and the developer's interactions with the programming environment. MimEc is currently under development and will be evaluated in both academic and professional settings.\",\n \"Title: Navigation for Data Analysis Systems\\nYear: 1997\\n\\nAbstract: . Statistical strategies are formal descriptions of the actionsand decisions involved in applying statistical tools to a problem. Onedifficult problem, beyond strategy design issues, is ensuring an effectiveinteraction between the the user and the implementation of the strategy.In this paper we review some existing techniques that have been effectivein mediating the interaction between users and expert statistical systemsfor data analysis. We explore the relationship between...\",\n \"Title: Toward automated exploration of interactive systems\\nYear: 2002\\n\\nAbstract: The ease with which a user interface can be navigated strongly contributes to its usability. In this paper we describe preliminary results of a project aimed at making the evaluation of user interfaces from this perspective more routine. We have designed a system to carry out an autonomous, exploratory navigation through the graphical user interface of interactive, off-the-shelf software applications. The system is not a robust tool, but rather a proof of concept that can exhibit interesting behaviors. The traversal process generates a representation of the connectivity of the user interface, as well as navigational paths to specific commands. The reasoning component of the system is based on the ACT-R architecture, while the perceptual and motor components of the system are built on top of the SegMan perception/action substrate. We present the design of the system and its use in exploring a simple user interface.\",\n \"Title: Visual generalization in programming by example\\nYear: 2000\\n\\nAbstract: In Programming by Example, the system records actions performed by a user in the interface, and produces a generalized program that can be used later in analogous examples. A key issue is how to describe the actions and objects selected by the user, which determines what kind of generalizations will be possible. When the user selects graphical objects on the screen, most PBE systems describe those objects using properties of the application data that the visual objects represent. For example, if the user selects a text label inside a box in a calendar program, the PBE system might represent that as selecting a particular appointment. In this article, we explore a different, and radical, approach -- using visual properties of the interaction elements themselves, such as size, shape, color, and appearance of graphical objects -- to describe user intentions. Only recently has the speed of image processing made feasible real-time analysis of screen images by a PBE system. We believe that this approach opens up some unique advantages. Foremost among them is that PBE systems can work from the visual appearance of applications, and do not need explicit cooperation from the application's API, thereby removing one of the worst stumbling-blocks preventing the use of PBE with commercial applications. Visually- oriented systems stick more closely to what the user can actually see, and so should be more transparent, especially for beginning users. Finally, they open up the possibility of new kinds of generalizations not anticipated by application designers or not possible from the application data alone.\",\n \"Title: Visual Perception and Mixed-Initiative Interaction for Assisted Visualization Design\\nYear: 2008\\n\\nAbstract: This paper describes the integration of perceptual guidelines from human vision with an AI-based mixed-initiative search strategy. The result is a visualization assistant called ViA, a system that collaborates with its users to identify perceptually salient visualizations for large, multidimensional datasets. ViA applies knowledge of low-level human vision to: (1) evaluate the effectiveness of a particular visualization for a given dataset and analysis tasks; and (2) rapidly direct its search towards new visualizations that are most likely to offer improvements over those seen to date. Context, domain expertise, and a high-level understanding of a dataset are critical to identifying effective visualizations. We apply a mixed-initiative strategy that allows ViA and its users to share their different strengths and continually improve ViA's understanding of a user's preferences. We visualize historical weather conditions to compare ViA's search strategy to exhaustive analysis, simulated annealing, and reactive tabu search, and to measure the improvement provided by mixed-initiative interaction. We also visualize intelligent agents competing in a simulated online auction to evaluate ViA's perceptual guidelines. Results from each study are positive, suggesting that ViA can construct high-quality visualizations for a range of real-world datasets.\",\n \"Title: User interface affordances in a planning representation\\nYear: 1999\\n\\nAbstract: This article shows how the concept of affordance in the user interface fits into a well-understood artificial intelligence (AI) model of acting in an environment. In this model AI planning research is used to interpret affordances in terms of the costs associated with the generation and execution of operators in a plan. This article motivates the approach with a brief survey of the affordance literature and its connections to the planning literature and then explores its implications through examples of common user interface mechanisms described in affordances terms. Despite its simplicity, the modeling approach ties together several different threads of practical and theoretical work on affordance into a single conceptual framework.\",\n \"Title: CAPTIVE: a cube with augmented physical tools\\nYear: 2014\\n\\nAbstract: This paper describes a tangible 3D user interface called CAPTIVE, a Cube with Augmented Physical Tools, for exploration of 3D information. The design of CAPTIVE is founded on the concept of tool use, in which handheld tool objects are used to modify the properties or appearance of target objects. The user of CAPTIVE holds a physical wireframe cube that contains virtual objects in one hand, in the other a pointing device, its tip visually augmented to reflect its function as a tool. On the display the user watches the immediate, direct effects of actions with the tool. In the current prototype, routines for handling cube manipulation and an augmented haptic pointing device have been separately implemented, but integration and refinement remain to be done. In this paper we describe our vision of the system and preliminary testing carried out to date.\",\n \"Title: A visual interface to a music database\\nYear: 2002\\n\\nAbstract: This paper describes a system for exploring and selecting entries from a music database through a visualization interface. The system is designed for deployment in situations in which the user's attention is a tightly limited resource. The system combines research topics in intelligent user interfaces, visualization techniques, and cognitive modeling. Informal evaluation of the system has given us useful insights into the design tradeoffs that developers may face when building visual interfaces for off-the-desktop applications.\",\n \"Title: Specifying ACT-R models of user interaction with a GOMS language\\nYear: 2005\\n\\nAbstract: We describe a system, G2A, that produces ACT-R models from GOMS models. The GOMS models can contain hierarchical methods, visual and memory stores, and control constructs. G2A allows ACT-R models to be built much more quickly, in hours rather than weeks. Because GOMS is a more abstract formalism than ACT-R, most GOMS operators can be plausibly translated in different ways into ACT-R productions (e.g., a GOMS Look-for operator can be carried out by different visual search strategies in ACT-R). Given a GOMS model, G2A generates and evaluates alternative ACT-R models by systematically varying the mapping of GOMS operators to ACT-R productions. In experiments with a text editing task, G2A produces ACT-R models whose predictions are within 5% of GOMS model predictions. In the same domain, G2A also generates ACT-R models that give better predictions than GOMS, providing good predictions of overall task duration for actual users (within 2%), though the models are less accurate at a detailed level. In a separate experiment with a mouse-driven telephone dialing task, G2A produces models that do a better job of distinguishing between competing interfaces than a Fitts' law model or an ACT-R model built by hand. G2A starts to describe the relationship between two major theories of cognition. This may have appeared a simple relationship, but the complexity of the translation illustrates why this was not done before. G2A shows a way forward for cognitive models, that of higher level languages that compile into more detailed specifications.\",\n \"Title: Evaluation of a semi-autonomous assistant for exploratory data analysis\\nYear: 1997\\n\\nAbstract: Aide is a knowledge-based planning assistant for intelligentdata exploration that draws on research inmixed-initiative planning and collaborative systems.Aide incrementally explores a dataset, guided by userdirectives and its own evaluation of the data. The systemis mixed-initiative: it semi-autonomously pursueshigh- and low-level goals but allows the user to reviewand potentially override its decisions. This paperbriefly describes the exploratory task, Aide's architecture,and how the ...\",\n \"Title: Assisted visualization of e-commerce auction agents\\nYear: 2001\\n\\nAbstract: This paper describes the integration of perceptual guidelines from human vision with an Al-based mixed-initiative search technique. The result is a visualization assistant, a system that identifies perceptually salient visualizations for large, multidimensional collections of data. Understanding how the low-level human visual system \\\"sees\\\" visual information in an image allows us to: (1) evaluate a particular visualization, and (2) direct the search algorithm towards new visualizations that may be better than those seen to date. In this way we can limit search to locations that have the highest potential to contain effective visualizations. One testbed application for this work is the visualization of intelligent e-commerce auction agents participating in a simulated online auction environment. We describe how the visualization assistant was used to choose methods to effectively visualize this data.\",\n \"Title: Tool use for autonomous agents\\nYear: 2005\\n\\nAbstract: The intelligent use of tools is a general and important human competence that AI research has not yet examined in depth. Other fields have studied the topic, however, with results we can compile into a broad characterization of habile (tool-using) agents. In this paper we give an overview of research on the use of physical tools, using this information to motivate the development of artificial habile agents. Specifically, we describe how research goals and methods in animal cognition overlap with those in artificial intelligence. We argue that analysis of activities of tool-using agents offers an informative way to evaluate intelligence.\",\n \"Title: Interaction with a mixed-initiative system for exploratory data analysis\\nYear: 1998\\n\\nAbstract: Exploratory data analysis (EDA) plays an increasinglyimportant role in statistical analysis. EDA is difficult,however, even with the help of modern statistical software.We have developed an assistant for data exploration,based on AI planning techniques, that addressessome of the strategic shortcomings of conventional software.This paper illustrates the behavior of the system,gives a high level description of its design, and discussesits experimental evaluation.KeywordsArtificial...\",\n \"Title: Links: AI planning resources on the Web\\nYear: 2001\\n\\nAbstract: With the introduction of new, efficient techniques for planning, interest in the field has risen sharply in recent years. Planning systems have come a long way since the days of Blocks World. Today, planning and scheduling techniques are being used to solve problems in military campaign planning, robot navigation, industrial equipment scheduling, human-computer interaction, and many other real-world domains. Planning, which is the process of finding a sequence of actions that meets an agents goal, is a thriving area of artificial intelligence (AI) research and is growing almost faster than one can keep track. Fortunately, an abundance of information about planning is available, in both paper and electronic forms; answers to most of the questions a newcomer to the field might ask can easily be found. What is planning?\",\n \"Title: Model-based evaluation of cell phone menu interaction\\nYear: 2004\\n\\nAbstract: Cell phone interfaces are now ubiquitous. In this paper, we describe concepts to support the analysis of cell phone menu hierarchies. We present an empirical study of user performance on five simple tasks of menu traversal on a cell phone. Two models we tested, based on GOMS and ACT-R, give very good predictions of behavior. We use the study results to motivate an effective evaluation process for menu hierarchies. Our work makes several contributions: a novel and timely study of a new, very common HCI task; new models for accurately predicting performance; novel development tools to support such modeling; and a search procedure to generate menu hierarchies that reduce traversal time, in simulation studies, by about a third.\",\n \"Title: Intelligent visualization in a planning simulation\\nYear: 2001\\n\\nAbstract: This paper describes a set of visualization techniques for interactive planning in a physical force simulation called AFS. We have developed a 3D environment in which textures are overlaid on a simulated landscape to convey information about environmental properties, agent actions, and possible strategies. Scenes are presented, via automated camera planning, such that some simple agent goals can be induced visually with little effort. These two areas of visualization functionality in AFS exploit properties of human low-level and intermediate-level vision, respectively. This paper presents AFS, its visualization environment, and studies we have run to explore the relationship between AFS visualizations and the high-level planning process.\",\n \"Title: Social navigation: modeling, simulation, and experimentation\\nYear: 2003\\n\\nAbstract: The term social navigation refers to the process of seeking social interaction as a source of navigational support. In this paper we present a computational model of social navigation as an extension to an existing conceptual, non-computational model of general navigation. We argue that such models are important in designing effective shared environments for information navigation. We describe support for the model with a simulation environment for social navigation and an analytical model that addresses some of the quantitative implications of social interaction on the process.\",\n \"Title: Balancing efficiency and interpretability in an interactive statistical assistant\\nYear: 2003\\n\\nAbstract: Making an interface more efficient, in a task analysis sense, can make it more difficult for an automated reasoning system to infer user goals, by eliminating some user actions, by presenting information without requiring overt user selection, and so forth. We call the extent to which a system can make such inferences interpretability. In this paper we describe the tradeoff between interpretability and efficiency. We give some general heuristics for improving interpretability in a system and explain how they apply in an implemented system, an assistant for exploratory statistical analysis. Increased interpretability in the system is provided by navigation techniques for data exploration and a data mountain for organizing results; a formative evaluation illustrates some of the potential benefits of applying interpretability heuristics to an intelligent user interface\",\n \"Title: CAVIAR: a vibrotactile device for accessible reaching\\nYear: 2012\\n\\nAbstract: CAVIAR is designed to aid people with vision impairment in locating, identifying, and acquiring objects in their peripersonal space. A mobile phone, worn on the chest, captures video in front of the user; the computer vision component locates the user's hand and objects in the video stream. The auditory component informs the user about the presence of objects. On user confirmation, the reaching component sends signals to vibrotactile actuators on the user's wristband, guiding the hand to a specific object. This paper describes an end-to-end prototype of CAVIAR and its formative evaluation.\",\n \"Title: Novice use of a predictive human performance modeling tool to produce UI recommendations\\nYear: 2014\\n\\nAbstract: This note describes two studies of the use of a performance modeling tool, CogTool, for making recommendations to improve a user interface. The first study replicates findings by Bonnie John [7]: the rates at which novice modelers made correct recommendations (88.1%) and supported them (68.2%) are close to the values in John's study (91.7% and 75.1%, respectively). A follow-on study of novice modelers on the same task without CogTool produced sig-nificantly lower values. CogTool improves the UI design recommendations made by novices.\",\n \"Title: Links: artificial intelligence and interactive entertainment\\nYear: 2001\\n\\nAbstract: As John Laird pointed out in his IAAI/AAAI invited talk last year, artificial intelligence research and computer gaming have quite a bit to offer one another. While many of the most commercially successful computer games have been rather visceral and violent in nature, AI techniques offer the promise of creating engaging and dynamic interactive entertainment with strong narrative components. The research challenges posed for AI researchers when addressing their work in the context of computers games are as complex and compelling as many \\\"actual-world\\\" problem areas and the context of gaming environments offers up unique interfaces, modes of use and an extensive existing base of potential users. In this article, we'll introduce some of the aspects of the application of artificial intelligence research in the context of interactive entertainment. While intelligent techniques are certainly applicable to a wide range of computer games, here we'll focus primarily on games that simulate or create highly interactive virtual environments - games where one or more users control various aspects of the game's world, either in discrete steps (i.e, turn-taking) or in continuous real-time modes.\",\n \"Title: A tool-based interactive drawing environment\\nYear: 2002\\n\\nAbstract: Graphical user interfaces rely heavily on the tool metaphor. In most drawing systems, for example, functions are organized as they might be on a workbench; buttons associated with drawing modes for lines or rectangles are called line-drawing or rectangle-drawing tools; etc. Despite the similarities, however, there remain many differences between software tools and physical tools. This paper gives a concise account of tool use in general, and describes a drawing application, called HabilisDraw, that relies on a detailed correspondence to physical tool behavior.\",\n \"Title: AI support for building cognitive models\\nYear: 2006\\n\\nAbstract: Cognitive modeling techniques provide a way of evaluating user interface designs, based on what is known about human cognitive strengths and limitations. Cognitive modelers face a tradeoff, however: more detailed models require disproportionately more time and effort to develop than coarser models. In this paper we describe a system, G2A, that automatically produces translations from abstract GOMS models into more detailed ACT-R models. G2A demonstrates how even simple AI techniques can facilitate the construction of cognitive models and suggests new directions for improving modeling tools.\",\n \"Title: Search for efficient device-dependent action sequences in the user interface\\nYear: 2003\\n\\nAbstract: This paper describes a design tool, under development, that identifies efficient low-level action sequences in the user interface, accounting for the relationships between the physical properties of an input device and the requirements of primitive tasks. A device representation and a task taxonomy are presented. These, along with a library of efficiency measures for specific devices, provide information to steer search through the space of action sequences.\",\n \"Title: A reduced QWERTY keyboard for mobile text entry\\nYear: 2004\\n\\nAbstract: In this paper we describe a specialized keyboard for text entry that maps four rows of a standard keyboard onto the home row, with different characters encoded via modifier keys and multi-tap input. Use of the keyboard also relies on lexicon-based disambiguation. This design has two motivations: limiting physical space requirements and capitalizing on user knowledge of the standard QWERTY keyboard layout. The resulting \\\"stick\\\" keyboard is between 15% and 25% of the size of a standard keyboard. In a preliminary empirical study, users reached half of their normal typing speed using lexicon-based disambiguation (22.5 wpm) and a reasonable but lower speed with multi-tap input (10.4 wpm) with only a few minutes of practice.\",\n \"Title: Toward the Integration of Exploration and Modeling in a Planning Framework\\nYear: 1994\\n\\nAbstract: Statistical operations are often facilitated by other operations. We can facilitate modeling operations by testing their input for irregularities and removing problems wherever possible. A planning representation is well-suited to this task. We describe the representation used in Igor, a system for exploratory data analysis, and its integration with two modeling systems, Pearl''s IC and Cohen''s FBD. We show that introducing outliers into the inputs of the algorithms can influence their performance. We demonstrate that a planning representation offers a flexible way of integrating outlier detection and removal into the modeling process, taking account of specific characteristics of the modeling operations involved.\",\n \"Title: Power tools and composite tools: integrating automation with direct manipulation\\nYear: 2003\\n\\nAbstract: This paper describes a drawing system that incorporates two novel interaction techniques based on analogies to physical tools. Power tools add limited autonomy in the form of rotators and movers for automated circular, linear, and Bezier-curve movement. Composite tools are user-constructed combinations of existing tools to create new functionality.\",\n \"Title: Detecting abnormal user behavior through pattern-mining input device analytics\\nYear: 2015\\n\\nAbstract: This paper presents a method for detecting patterns in the usage of a computer mouse that can give insights into user's cognitive processes. We conducted a study using a computer version of the Memory game (also known as the Concentration game) that allowed some participants to reveal the content of the tiles, expecting their low-level mouse interaction patterns to deviate from those of normal players with no access to this information. We then trained models to detect these differences using task-independent input device features. The models detected cheating with 98.73% accuracy for players who cheated or did not cheat consistently for entire rounds of the game, and with 89.18% accuracy for cases in which players enabled and then disabled cheating within rounds.\",\n \"Title: Exploring key-level analytics for computational modeling of typing behavior\\nYear: 2014\\n\\nAbstract: Typing is a human activity that can be affected by a number of situational and task-specific factors. Changes in typing behavior resulting from the manipulation of such factors can be predictably observed through key-level input analytics. Here we present a study designed to explore these relationships. Participants play a typing game in which letter composition, word length and number of words appearing together are varied across levels. Inter-keystroke timings and other higher order statistics (such as bursts and pauses), as well as typing strategies, are analyzed from game logs to find the best set of metrics that quantify the effect that different experimental factors have on observable metrics. Beyond task-specific factors, we also study the effects of habituation by recording changes in performance with practice. Currently a work in progress, this research aims at developing a predictive model of human typing. We believe this insight can lead to the development of novel security proofs for interactive systems that can be deployed on existing infrastructure with minimal overhead. Possible applications of such predictive capabilities include anomalous behavior detection, authentication using typing signatures, bot detection using word challenges etc.\",\n \"Title: Integrating statistical methods for characterizing causal influences on planner behavior over time\\nYear: 1994\\n\\nAbstract: Statistical causal modeling techniques allow us to develop models of program behavior, but these techniques tend to be limited in what they can model: either continuing, repetitive influences or causal influences without cycles, but not both as appear in many environments. The paper describes how two statistical modeling techniques can be combined to suggest and test specific hypotheses about how the environment and the AI planner's design causally influence the planner's behavior. One technique, dependency detection, is designed to identify relationships (dependencies) between particular failures, the methods that repair them and the occurrence of failures downstream. Another method, path analysis, builds causal models of correlational data. Dependency detection operates over a series of events, and path analysis models within a temporal snapshot. We explain the integration of the techniques and demonstrate it on execution data from the Phoenix planner\",\n \"Title: A Partial Contour Similarity-Based Approach to Visual Affordances in Habile Agents\\nYear: 2017\\n\\nAbstract: In a typical tool use task, we can view both the relationship between the agent and the tool and the relationship between the tool and the target in terms of affordances. One set of affordances relates to the ability of the agent to manipulate the tool, while a second set of affordances relates to the ability of the agent to manipulate the target by means of the tool. In both cases, effective tool...\",\n \"Title: Natural Interaction with Visualization Systems\\nYear: 2015\\n\\nAbstract: As new input devices and interaction techniques emerge daily, how might they improve interactive visualization?\",\n \"Title: Control Representation in an EDA Assistant\\nYear: 1995\\n\\nAbstract: To develop an initial understanding of complex data, one often begins with exploration. Exploratory data analysis (EDA) provides a set of statistical tools through which patterns in data may be extracted and examined in detail. The search space of EDA operations is enormous, too large to be explored directly in a data-driven manner. More abstract EDA procedures can be captured, however, by representations commonly used in AI planning systems. We describe an implemented planning representation for \\\\aide/, an automated EDA assistant, with a focus on control issues.\",\n \"Title: Natural Interaction for Bot Detection.\\nYear: 2016\\n\\nAbstract: Bot detection - identifying a software program that's using a computer system -- is an increasingly necessary security task. Existing solutions balance proof of human identity with unobtrusiveness in users' workflows. Cognitive modeling and natural interaction might provide stronger security and less intrusiveness.\",\n \"Title: Human Subtlety Proofs: Using Computer Games To Model Cognitive Processes For Cybersecurity\\nYear: 2017\\n\\nAbstract: This article describes an emerging direction in the intersection between human-computer interaction and cognitive science: the use of cognitive models to give insight into the challenges of cybersecurity (cyber-SA). The article gives a brief overview of work in different areas of cyber-SA where cognitive modeling research plays a role, with regard to direct interaction between end users and computer systems and with regard to the needs of security analysts working behind the scenes. The problem of distinguishing between human users and automated agents (bots) interacting with computer systems is introduced, as well as ongoing efforts toward building Human Subtlety Proofs (HSPs), persistent and unobtrusive windows into human cognition with direct application to cyber-SA. Two computer games are described, proxies to illustrate different ways in which cognitive modeling can potentially contribute to the development of HSPs and similar cyber-SA applications.\",\n \"Title: Usability guidelines for interactive search in direct manipulation systems\\nYear: 2001\\n\\nAbstract: Extracting rules from RBFs is not a trivial task because of nonlinear functions or high input dimensionality. In such cases, some of the hidden units of the RBF network have a tendency to be \\\"shared\\\" across several output classes or even may not contribute ...\",\n \"Title: Performance Characteristics of a Camera-Based Tangible Input Device for Manipulation of 3D Information.\\nYear: 2017\\n\\nAbstract: This paper describes a prototype tangible six degree of freedom (6 DoF) input device that is inexpensive and intuitive to use: a cube with colored corners of specific shapes, tracked by a single camera, with pose estimated in real time. A tracking and automatic color adjustment system are designed so that the device can work robustly with noisy surroundings and is invariant to changes in lighting and background noise. A system evaluation shows good performance for both refresh (above 60 FPS on average) and accuracy of pose estimation (average angular error of about 1). A user study of 3D rotation tasks shows that the device outperforms other 6 DoF input devices used in a similar desktop environment. The device has the potential to facilitate interactive applications such as games as well as viewing 3D information.\",\n \"Title: Spoken language interaction with robots: Recommendations for future research\\nYear: 2022\\n\\nAbstract: With robotics rapidly advancing, more effective human-robot interaction is increasingly needed to realize the full potential of robots for society. While spoken language must be part of the solution, our ability to provide spoken language interaction capabilities is still very limited. In this article, based on the report of an interdisciplinary workshop convened by the National Science Foundation, we identify key scientific and engineering advances needed to enable effective spoken language interaction with robotics. We make 25 recommendations, involving eight general themes: putting human needs first, better modeling the social and interactive aspects of language, improving robustness, creating new methods for rapid adaptation, better integrating speech and language with other communication modalities, giving speech and language components access to rich representations of the robot's current knowledge and state, making all components operate in real time, and improving research infrastructure and resources. Research and development that prioritizes these topics will, we believe, provide a solid foundation for the creation of speech-capable robots that are easy and effective for humans to work with.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":61,"string":"61"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":287,"string":"287"}}},{"rowIdx":288,"cells":{"question_id":{"kind":"string","value":"Tanzeem Choudhury"},"question":{"kind":"string","value":"Generate an abstract for the title \"Keppi: A Tangible User Interface for Self-Reporting Pain.\" using the following items: Chronic pain, tangible user interface (TUI), self-report, wearable, pain assessment."},"answer":{"kind":"string","value":"Motivated by the need to support those managing chronic pain, we report on the iterative design, development, and evaluation of Keppi, a novel pressure-based tangible user interface (TUI) for the self-report of pain intensity. In-lab studies with 28 participants found individuals were able to use Keppi to reliably report low, medium, and high pain as well as map squeeze pressure to pain level. Based on insights from these evaluations, we ultimately created a wearable version of Keppi with multiple form factors, including a necklace, bracelet, and keychain. Interviews indicated high receptivity to the wearable design, which satisfied additional user-identified needs (e.g., discreet and convenient) and highlighted key directions for the continued refinement of tangible devices for pain assessment."},"correct_answer":{"kind":"string","value":"Motivated by the need to support those managing chronic pain, we report on the iterative design, development, and evaluation of Keppi, a novel pressure-based tangible user interface (TUI) for the self-report of pain intensity. In-lab studies with 28 participants found individuals were able to use Keppi to reliably report low, medium, and high pain as well as map squeeze pressure to pain level. Based on insights from these evaluations, we ultimately created a wearable version of Keppi with multiple form factors, including a necklace, bracelet, and keychain. Interviews indicated high receptivity to the wearable design, which satisfied additional user-identified needs (e.g., discreet and convenient) and highlighted key directions for the continued refinement of tangible devices for pain assessment."},"documents":{"kind":"list like","value":["Title: Community Similarity Networks\nYear: 2014\n\nAbstract: Sensor-enabled smartphones are opening a new frontier in the development of mobile sensing applications. The recognition of human activities and context from sensor data using classification models underpins these emerging applications. However, conventional approaches to training classifiers struggle to cope with the diverse user populations routinely found in large-scale popular mobile applications. Differences between users (e.g., age, sex, behavioral patterns, lifestyle) confuse classifiers, which assume everyone is the same. To address this, we propose Community Similarity Networks (CSN), which incorporates inter-person similarity measurements into the classifier training process. Under CSN, every user has a unique classifier that is tuned to their own characteristics. CSN exploits crowd-sourced sensor data to personalize classifiers with data contributed from other similar users. This process is guided by similarity networks that measure different dimensions of inter-person similarity. Our experiments show CSN outperforms existing approaches to classifier training under the presence of population diversity.","Title: StressSense: detecting stress in unconstrained acoustic environments using smartphones\nYear: 2012\n\nAbstract: Stress can have long term adverse effects on individuals' physical and mental well-being. Changes in the speech production process is one of many physiological changes that happen during stress. Microphones, embedded in mobile phones and carried ubiquitously by people, provide the opportunity to continuously and non-invasively monitor stress in real-life situations. We propose StressSense for unobtrusively recognizing stress from human voice using smartphones. We investigate methods for adapting a one-size-fits-all stress model to individual speakers and scenarios. We demonstrate that the StressSense classifier can robustly identify stress across multiple individuals in diverse acoustic environments: using model adaptation StressSense achieves 81% and 76% accuracy for indoor and outdoor environments, respectively. We show that StressSense can be implemented on commodity Android phones and run in real-time. To the best of our knowledge, StressSense represents the first system to consider voice based stress detection and model adaptation in diverse real-life conversational situations using smartphones.","Title: Biological rhythms and technology\nYear: 2014\n\nAbstract: Biological rhythms enable living organisms to adapt and live with periodical environmental changes, such as variation in the relative position of the earth and the sun. Internal rhythms, like body temperature and sleep-wake cycle, are driven by numerous biological processes and can be maintained even in the absence of external environmental cues. These rhythms affect how we feel, think, and act. They are profoundly important for our health, quality of sleep, and mood. Yet the digital devices we use are ignorant of our biology. They respond uniformly to our touch and click. Recently there has been a considerable increase of research within the HCI community to support behavior change, personal insight, and increase productivity. This workshop will bring together researchers in sleep, wellbeing, and circadian rhythms to discuss the possibility of rhythm systems: technologies that play to the strengths of our biology. It will investigate how HCI can complement our biological rhythms and will focus on two areas: measurement and intervention.","Title: Activity-aware ECG-based patient authentication for remote health monitoring\nYear: 2009\n\nAbstract: Mobile medical sensors promise to provide an efficient, accurate, and economic way to monitor patients' health outside the hospital. Patient authentication is a necessary security requirement in remote health monitoring scenarios. The monitoring system needs to make sure that the data is coming from the right person before any medical or financial decisions are made based on the data. Credential-based authentication methods (e.g., passwords, certificates) are not well-suited for remote healthcare as patients could hand over credentials to someone else. Furthermore, one-time authentication using credentials or trait-based biometrics (e.g., face, fingerprints, iris) do not cover the entire monitoring period and may lead to unauthorized post-authentication use. Recent studies have shown that the human electrocardiogram (ECG) exhibits unique patterns that can be used to discriminate individuals. However, perturbation of the ECG signal due to physical activity is a major obstacle in applying the technology in real-world situations. In this paper, we present a novel ECG and accelerometer-based system that can authenticate individuals in an ongoing manner under various activity conditions. We describe the probabilistic authentication system we have developed and present experimental results from 17 individuals.","Title: Exploiting Social Networks for Large-Scale Human Behavior Modeling\nYear: 2011\n\nAbstract: The Cooperative Communities (CoCo) learning framework leverages everyday social connections between people to personalize classification models. By exploiting social networks, CoCo spreads the burden of providing training data over an entire community.","Title: Exploring Privacy Concerns about Personal Sensing\nYear: 2009\n\nAbstract: More and more personal devices such as mobile phones and multimedia players use embedded sensing. This means that people are wearing and carrying devices capable of sensing details about them such as their activity, location, and environment. In this paper, we explore privacy concerns about such personal sensing through interviews with 24 participants who took part in a three month study that used personal sensing to detect their physical activities. Our results show that concerns often depended on what was being recorded, the context in which participants worked and lived and thus would be sensed, and the value they perceived would be provided. We suggest ways in which personal sensing can be made more privacy-sensitive to address these concerns.","Title: MoodRhythm: tracking and supporting daily rhythms\nYear: 2013\n\nAbstract: Rhythms guide our lives. Our biological clocks tell us when we need to sleep, eat and wake. But our use of technology can interrupt and obstruct these rhythms, making it difficult for our bodies to get what they need to stay healthy and balanced. Our MoodRhythm app helps individuals to live a more naturally rhythmic day. The key goals of MoodRhythm are to use patients' smartphones to actively and passively track daily rhythms and to provide affective feedback that can help patients to maintain a regular daily rhythm, while feeding this clinically valuable information back to their physicians.","Title: A hybrid discriminative/generative approach for modeling human activities\nYear: 2005\n\nAbstract: Accurate recognition and tracking of human activities is an important goal of ubiquitous computing. Recent advances in the development of multi-modal wearable sensors enable us to gather rich datasets of human activities. However, the problem of automatically identifying the most useful features for modeling such activities remains largely unsolved. In this paper we present a hybrid approach to recognizing activities, which combines boosting to discriminatively select useful features and learn an ensemble of static classifiers to recognize different activities, with hidden Markov models (HMMs) to capture the temporal regularities and smoothness of activities. We tested the activity recognition system using over 12 hours of wearable-sensor data collected by volunteers in natural unconstrained environments. The models succeeded in identifying a small set of maximally informative features, and were able identify ten different human activities with an accuracy of 95%.","Title: Mobility detection using everyday GSM traces\nYear: 2006\n\nAbstract: Recognition of everyday physical activities is difficult due to the challenges of building informative, yet unobtrusive sensors. The most widely deployed and used mobile computing device today is the mobile phone, which presents an obvious candidate for recognizing activities. This paper explores how coarse-grained GSM data from mobile phones can be used to recognize high-level properties of user mobility, and daily step count. We demonstrate that even without knowledge of observed cell tower locations, we can recognize mobility modes that are useful for several application domains. Our mobility detection system was evaluated with GSM traces from the everyday lives of three data collectors over a period of one month, yielding an overall average accuracy of 85%, and a daily step count number that reasonably approximates the numbers determined by several commercial pedometers.","Title: Building reliable activity models using hierarchical shrinkage and mined ontology\nYear: 2006\n\nAbstract: Activity inference based on object use has received considerable recent attention. Such inference requires statistical models that map activities to the objects used in performing them. Proposed techniques for constructing these models (hand definition, learning from data, and web extraction) all share the problem of model incompleteness: it is difficult to either manually or automatically identify all the possible objects that may be used to perform an activity, or to accurately calculate the probability with which they will be used. In this paper, we show how to use auxiliary information, called an ontology, about the functional similarities between objects to mitigate the problem of model incompleteness. We show how to extract a large, relevant ontology automatically from WordNet, an online lexical reference system for the English language. We adapt a statistical smoothing technique, called shrinkage, to apply this similarity information to counter the incompleteness of our models. Our results highlight two advantages of performing shrinkage. First, overall activity recognition accuracy improves by 15.11% by including the ontology to re-estimate the parameters of models that are automatically mined from the web. Shrinkage can therefore serve as a technique for making web-mined activity models more attractive. Second, smoothing yields an increased recognition accuracy when objects not present in the incomplete models are used while performing an activity. When we replace 100% of the objects with other objects that are functionally similar, we get an accuracy drop of only 33% when using shrinkage as opposed to 91.66% (equivalent to random guessing) without shrinkage. If training data is available, shrinkage further improves classification accuracy.","Title: Modeling Conversational Dynamics as a Mixed-Memory Markov Process\nYear: 2004\n\nAbstract: In this work, we quantitatively investigate the ways in which a given person influences the joint turn-taking behavior in a conversation. After collecting an auditory database of social interactions among a group of twenty-three people via wearable sensors (66 hours of data each over two weeks), we apply speech and conversation detection methods to the auditory streams. These methods automatically locate the conversations, determine their participants, and mark which participant was speaking when. We then model the joint turn-taking behavior as a Mixed-Memory Markov Model (1) that combines the statistics of the individual subjects' self-transitions and the partners' cross-transitions. The mixture parameters in this model describe how much each person's individual behavior contributes to the joint turn-taking behavior of the pair. By estimating these parameters, we thus estimate how much influence each participant has in determining the joint turn- taking behavior. We show how this measure correlates significantly with betweenness centrality (2), an independent measure of an individual's importance in a social network. This result suggests that our estimate of conversational influence is predictive of social influence.","Title: Human dynamics: computation for organizations: Human dynamics: computation for organizations\nYear: 2005\n\nAbstract: The human dynamics group at the MIT Media Laboratory proposes that active pattern analysis of face-to-face interactions within the workplace can radically improve the functioning of the organization. There are several different types of information inherent in such conversations: interaction features, participants, context, and content. By aggregating this information, high-potential collaborations and expertise within the organization can be identified, and information efficiently distributed. Examples of using wearable machine perception to characterize face-to-face interactions and using the results to initiate productive connections are described, and privacy concerns are addressed.","Title: BeWell+: multi-dimensional wellbeing monitoring with community-guided user feedback and energy optimization\nYear: 2012\n\nAbstract: Smartphone sensing and persuasive feedback design is enabling a new generation of wellbeing applications capable of automatically monitoring multiple aspects of physical and mental health. In this paper, we present BeWell+ the next generation of the BeWell smartphone health app, which continuously monitors user behavior along three distinct health dimensions, namely sleep, physical activity, and social interaction. BeWell promotes improved behavioral patterns via feedback rendered as an ambient display on the smartphone's wallpaper. With BeWell+, we introduce new wellbeing mechanisms to address challenges identified during the initial deployment of the BeWell app; specifically, (i) community adaptive wellbeing feedback, which automatically generalize to diverse user communities (e.g., elderly, young adults, children) by balancing the need to promote better behavior yet remains realistic to the user's goals; and, (ii) wellbeing adaptive energy allocation, which prioritizes monitoring fidelity and feedback responsiveness on specific health dimensions of wellbeing (e.g., social interaction) where the user needs most help. We evaluate the performance of these mechanisms as part of an initial deployment and user study that includes 27 people using BeWell+ over a 19 day field trial. Our findings show that not only can BeWell+ operate successfully on consumer-grade smartphones, but users understand feedback and respond by taking positive steps towards leading healthier lifestyles.","Title: Tracking Mental Well-Being: Balancing Rich Sensing and Patient Needs\nYear: 2014\n\nAbstract: Serious mental illnesses are among the most pressing public healthcare concerns. Continuous and unobtrusive sensing of social and physical functioning has tremendous potential to support lifelong health management by acting as an early warning system to detect changes in mental well-being, delivering context-aware micro-interventions to patients when and where they need them and significantly accelerating patients' understanding of their illness.","Title: Learning hidden curved exponential family models to infer face-to-face interaction networks from situated speech data\nYear: 2008\n\nAbstract: In this paper, we present a novel probabilistic framework for recovering global, latent social network structure from local, noisy observations. We extend curved exponential random graph models to include two types of variables: hidden variables that capture the structure of the network and observational variables that capture the behavior between actors in the network. We develop a novel combination of informative and intuitive conversational (local) and structural (global) features to specify our model. The model learns, in an unsupervised manner, the relationship between observable behavior and hidden social structure while simultaneously learning properties of the latent structure itself. We present empirical results on both synthetic data and a real world dataset of face-to-face conversations collected from 24 individuals using wearable sensors over the course of 6 months.","Title: Inferring colocation and conversation networks from privacy-sensitive audio with implications for computational social science\nYear: 2011\n\nAbstract: New technologies have made it possible to collect information about social networks as they are acted and observed in the wild, instead of as they are reported in retrospective surveys. These technologies offer opportunities to address many new research questions: How can meaningful information about social interaction be extracted from automatically recorded raw data on human behavior? What can we learn about social networks from such fine-grained behavioral data? And how can all of this be done while protecting privacy? With the goal of addressing these questions, this article presents new methods for inferring colocation and conversation networks from privacy-sensitive audio. These methods are applied in a study of face-to-face interactions among 24 students in a graduate school cohort during an academic year. The resulting analysis shows that networks derived from colocation and conversation inferences are quite different. This distinction can inform future research in computational social science, especially work that only measures colocation or employs colocation data as a proxy for conversation networks.","Title: Technology Development for Building Flexible Silicon Functional Fibres\nYear: 2003\n\nAbstract: Most of everyday clothing consists of textile fibres woventogether to produce a fabric.Their primary purpose isstructural and aesthetic. Fibres can have added functionalityby the integration of computing power into the material thatforms them. The purpose of the 'fibre computing' concept is tointegrate this new dimension of functionality into fibres, thusturning everyday clothing objects into intelligent artefacts.","Title: A Scalable Approach to Activity Recognition based on Object Use\nYear: 2007\n\nAbstract: We propose an approach to activity recognition based on detecting and analyzing the sequence of objects that are being manipulated by the user. In domains such as cooking, where many activities involve similar actions, object-use information can be a valuable cue. In order for this approach to scale to many activities and objects, however, it is necessary to minimize the amount of human-labeled data that is required for modeling. We describe a method for automatically acquiring object models from video without any explicit human supervision. Our approach leverages sparse and noisy readings from RFID tagged objects, along with common-sense knowledge about which objects are likely to be used during a given activity, to bootstrap the learning process. We present a dynamic Bayesian network model which combines RFID and video data to jointly infer the most likely activity and object labels. We demonstrate that our approach can achieve activity recognition rates of more than 80% on a real-world dataset consisting of 16 household activities involving 33 objects with significant background clutter. We show that the combination of visual object recognition with RFID data is significantly more effective than the RFID sensor alone. Our work demonstrates that it is possible to automatically learn object models from video of household activities and employ these models for activity recognition, without requiring any explicit human labeling.","Title: Common sense based joint training of human activity recognizers\nYear: 2007\n\nAbstract: Given sensors to detect object use, commonsense priors of object usage in activities can reduce the need for labeled data in learning activity models. It is often useful, however, to understand how an object is being used, i.e., the action performed on it. We show how to add personal sensor data (e.g., accelerometers) to obtain this detail, with little labeling and feature selection overhead. By synchronizing the personal sensor data with object-use data, it is possible to use easily specified commonsense models to minimize labeling overhead. Further, combining a generative common sense model of activity with a discriminative model of actions can automate feature selection. On observed activity data, automatically trained action classifiers give 40/85% precision/recall on 10 actions. Adding actions to pure object-use improves precision/recall from 76/85% to 81/90% over 12 activities.","Title: Unsupervised activity recognition using automatically mined common sense\nYear: 2005\n\nAbstract: A fundamental difficulty in recognizing human activities is obtaining the labeled data needed to learn models of those activities. Given emerging sensor technology, however, it is possible to view activity data as a stream of natural language terms. Activity models are then mappings from such terms to activity names, and may be extracted from text corpora such as the web. We show that models so extracted are sufficient to automatically produce labeled segmentations of activity data with an accuracy of 42% over 26 activities, well above the 3.89% baseline. The segmentation so obtained is sufficient to bootstrap learning, with accuracy of learned models increasing to 52%. To our knowledge, this is the first human activity inferencing system shown to learn from sensed activity data with no human intervention per activity learned, even for labeling.","Title: BodyBeat: a mobile system for sensing non-speech body sounds\nYear: 2014\n\nAbstract: In this paper, we propose BodyBeat, a novel mobile sensing system for capturing and recognizing a diverse range of non-speech body sounds in real-life scenarios. Non-speech body sounds, such as sounds of food intake, breath, laughter, and cough contain invaluable information about our dietary behavior, respiratory physiology, and affect. The BodyBeat mobile sensing system consists of a custom-built piezoelectric microphone and a distributed computational framework that utilizes an ARM microcontroller and an Android smartphone. The custom-built microphone is designed to capture subtle body vibrations directly from the body surface without being perturbed by external sounds. The microphone is attached to a 3D printed neckpiece with a suspension mechanism. The ARM embedded system and the Android smartphone process the acoustic signal from the microphone and identify non-speech body sounds. We have extensively evaluated the BodyBeat mobile sensing system. Our results show that BodyBeat outperforms other existing solutions in capturing and recognizing different types of important non-speech body sounds.","Title: Fast and Scalable Training of Semi-Supervised CRFs with Application to Activity Recognition\nYear: 2007\n\nAbstract: We present a new and efficient semi-supervised training method for parameter es- timation and feature selection in conditional random fields (CRFs). In real-world applications such as activity recognition, unlabeled sensor traces are relatively easy to obtain whereas labeled examples are expensive and tedious to collect. Furthermore, the ability to automatically select a small subset of discriminatory features from a large pool can be advantageous in terms of computational speed as well as accuracy. In this paper, we introduce the semi-supervised virtual evidence boosting (sVEB) algorithm for training CRFs - a semi-supervised extension to the recently developed virtual evidence boosting (VEB) method for feature selection and parameter learning. The objective function of sVEB combines the unlabeled conditional entropy with labeled conditional pseudo-likelihood. It reduces the overall system cost as well as the human labeling cost required during training, which are both important considerations in building real-world inference systems. Experiments on synthetic data and real activity traces collected from wearable sensors, illustrate that sVEB benefits from both the use of unlabeled data and au- tomatic feature selection, and outperforms other semi-supervised approaches.","Title: The Jigsaw continuous sensing engine for mobile phone applications\nYear: 2010\n\nAbstract: Supporting continuous sensing applications on mobile phones is challenging because of the resource demands of long-term sensing, inference and communication algorithms. We present the design, implementation and evaluation of the Jigsaw continuous sensing engine, which balances the performance needs of the application and the resource demands of continuous sensing on the phone. Jigsaw comprises a set of sensing pipelines for the accelerometer, microphone and GPS sensors, which are built in a plug and play manner to support: i) resilient accelerometer data processing, which allows inferences to be robust to different phone hardware, orientation and body positions; ii) smart admission control and on-demand processing for the microphone and accelerometer data, which adaptively throttles the depth and sophistication of sensing pipelines when the input data is low quality or uninformative; and iii) adaptive pipeline processing, which judiciously triggers power hungry pipeline stages (e.g., sampling the GPS) taking into account the mobility and behavioral patterns of the user to drive down energy costs. We implement and evaluate Jigsaw on the Nokia N95 and the Apple iPhone, two popular smartphone platforms, to demonstrate its capability to recognize user activities and perform long term GPS tracking in an energy-efficient manner.","Title: Unobtrusive sleep monitoring using smartphones\nYear: 2013\n\nAbstract: How we feel is greatly influenced by how well we sleep. Emerging quantified-self apps and wearable devices allow people to measure and keep track of sleep duration, patterns and quality. However, these approaches are intrusive, placing a burden on the users to modify their daily sleep related habits in order to gain sleep data; for example, users have to wear cumbersome devices (e.g., a headband) or inform the app when they go to sleep and wake up. In this paper, we present a radically different approach for measuring sleep duration based on a novel best effort sleep (BES) model. BES infers sleep using smartphones in a completely unobtrusive way - that is, the user is completely removed from the monitoring process and does not interact with the phone beyond normal user behavior. A sensor-based inference algorithm predicts sleep duration by exploiting a collection of soft hints that tie sleep duration to various smartphone usage patterns (e.g., the time and length of smartphone usage or recharge events) and environmental observations (e.g., prolonged silence and darkness). We perform quantitative and qualitative comparisons between two smartphone only approaches that we developed (i.e., BES model and a sleep-with-the-phone approach) and two popular commercial wearable systems (Le., the Zeo headband and Jawbone wristband). Results from our one-week 8-person study look very promising and show that the BES model can accurately infer sleep duration (± 42 minutes) using a completely \"hands off\" approach that can cope with the natural variation in users' sleep routines and environments.","Title: Darwin phones: the evolution of sensing and inference on mobile phones\nYear: 2010\n\nAbstract: We present Darwin, an enabling technology for mobile phone sensing that combines collaborative sensing and classification techniques to reason about human behavior and context on mobile phones. Darwin advances mobile phone sensing through the deployment of efficient but sophisticated machine learning techniques specifically designed to run directly on sensor-enabled mobile phones (i.e., smartphones). Darwin tackles three key sensing and inference challenges that are barriers to mass-scale adoption of mobile phone sensing applications: (i) the human-burden of training classifiers, (ii) the ability to perform reliably in different environments (e.g., indoor, outdoor) and (iii) the ability to scale to a large number of phones without jeopardizing the \"phone experience\" (e.g., usability and battery lifetime). Darwin is a collaborative reasoning framework built on three concepts: classifier/model evolution, model pooling, and collaborative inference. To the best of our knowledge Darwin is the first system that applies distributed machine learning techniques and collaborative inference concepts to mobile phones. We implement the Darwin system on the Nokia N97 and Apple iPhone. While Darwin represents a general framework applicable to a wide variety of emerging mobile sensing applications, we implement a speaker recognition application and an augmented reality application to evaluate the benefits of Darwin. We show experimental results from eight individuals carrying Nokia N97s and demonstrate that Darwin improves the reliability and scalability of the proof-of-concept speaker recognition application without additional burden to users.","Title: Sensing and Modeling Human Networks using the Sociometer\nYear: 2003\n\nAbstract: Knowledge of how people interact is important in manydisciplines, e.g. organizational behavior, social networkanalysis, information diffusion and knowledge managementapplications. We are developing methods to automaticallyand unobtrusively learn the social network structures thatarise within human groups based on wearable sensors. Atpresent researchers mainly have to rely on questionnaires,surveys or diaries in order to obtain data on physicalinteractions between people. In this paper, we show howsensor measurements from the sociometer can be used tobuild computational models of group interactions. Wepresent results on how we can learn the structure of face-to-face interactions within groups, detect when membersare in face-to-face proximity and also when they are havinga conversation.","Title: Passive and In-situ Assessment of Mental and Physical Well-being using Mobile Sensors.\nYear: 2011\n\nAbstract: The idea of continuously monitoring well-being using mobile-sensing systems is gaining popularity. In-situ measurement of human behavior has the potential to overcome the short comings of gold-standard surveys that have been used for decades by the medical community. However, current sensing systems have mainly focused on tracking physical health; some have approximated aspects of mental health based on proximity measurements but have not been compared against medically accepted screening instruments. In this paper, we show the feasibility of a multi-modal mobile sensing system to simultaneously assess mental and physical health. By continuously capturing fine grained motion and privacy-sensitive audio data, we are able to derive different metrics that reflect the results of commonly used surveys for assessing well-being by the medical community. In addition, we present a case study that highlights how errors in assessment due to the subjective nature of the responses could potentially be avoided by continuous sensing and inference of social interactions and physical activities.","Title: Training conditional random fields using virtual evidence boosting\nYear: 2007\n\nAbstract: While conditional random fields (CRFs) have been applied successfully in a variety of domains, their training remains a challenging task. In this paper, we introduce a novel training method for CRFs, called virtual evidence boosting, which simultaneously performs feature selection and parameter estimation. To achieve this, we extend standard boosting to handle virtual evidence, where an observation can be specified as a distribution rather than a single number. This extension allows us to develop a unified framework for learning both local and compatibility features in CRFs. In experiments on synthetic data as well as real activity classification problems, our new training algorithm outperforms other training approaches including maximum likelihood, maximum pseudo-likelihood, and the most recent boosted random fields.","Title: The Mobile Sensing Platform: An Embedded Activity Recognition System\nYear: 2008\n\nAbstract: The Mobile Sensing Platform (MSP) is a small-form-factor wearable device designed for embedded activity recognition. The MSP aims broadly to support context-aware ubiquitous computing applications. It incorporates multimodal sensing, data processing and inference, storage, all-day battery life, and wireless connectivity into a single 4 oz (115 g) wearable unit. Several design iterations and real-world deployments over the last four years have identified a set of core hardware and software requirements for a mobile inference system. This article presents findings and lessons learned in the course of designing, improving and using this system. This article is part of a special issue on activity-based computing.","Title: Enabling large-scale human activity inference on smartphones using community similarity networks (csn)\nYear: 2011\n\nAbstract: Sensor-enabled smartphones are opening a new frontier in the development of mobile sensing applications. The recognition of human activities and context from sensor-data using classification models underpins these emerging applications. However, conventional approaches to training classifiers struggle to cope with the diverse user populations routinely found in large-scale popular mobile applications. Differences between users (e.g., age, sex, behavioral patterns, lifestyle) confuse classifiers, which assume everyone is the same. To address this, we propose Community Similarity Networks (CSN), which incorporates inter-person similarity measurements into the classifier training process. Under CSN every user has a unique classifier that is tuned to their own characteristics. CSN exploits crowd-sourced sensor-data to personalize classifiers with data contributed from other similar users. This process is guided by similarity networks that measure different dimensions of inter-person similarity. Our experiments show CSN outperforms existing approaches to classifier training under the presence of population diversity.","Title: A privacy-sensitive approach to modeling multi-person conversations\nYear: 2007\n\nAbstract: In this paper we introduce a new dynamic Bayesian network that separates the speakers and their speaking turns in a multi-person conversation. We protect the speakers' privacy by using only features from which intelligible speech cannot be reconstructed. The model we present combines data from multiple audio streams, segments the streams into speech and silence, separates the different speakers, and detects when other nearby individuals who are not wearing microphones are speaking. No pre-trained speaker specific models are used, so the system can be easily applied in new and different environments. We show promising results in two very different datasets that vary in background noise, microphone placement and quality, and conversational dynamics.","Title: Towards the automated social analysis of situated speech data\nYear: 2008\n\nAbstract: We present an automated approach for studying fine-grained details of social interaction and relationships. Specifically, we analyze the conversational characteristics of a group of 24 individuals over a six-month period, explore the relationship between conversational dynamics and network position, and identify behavioral correlates of tie strengths within a network. The ability to study conversational dynamics and social networks over long time scales, and to investigate their interplay with rigor, objectivity, and transparency will complement the traditional methods for scientific inquiry into social dynamics. They may also enable socially aware ubiquitous computing systems that are cognizant of and responsive to the user's engagement with her social environment.","Title: Towards Activity Databases: Using Sensors and Statistical Models to Summarize People's Lives\nYear: 2006\n\nAbstract: Automated reasoning about human behavior is a central goal of artificial intelligence. In order to engage and intervene in a meaningful way, an intelligent system must be able to understand what hu- mans are doing, their goals and intentions. Furthermore, as social animals, people's interactions with each other underlie many aspects of their lives: how they learn, how they work, how they play and how they affect the broader community. Understanding people's interactions and their social networks will play an important role in designing technology and applications that are \"socially-aware\". This paper introduces some of the current approaches in activity recognition which use a variety of different sensors to collect data about users' activities, and probabilistic models and relational information that are used to transform the raw sensor data into higher-level descriptions of people's behaviors and interactions. The end result of these methods is a richly structured dataset describing people's daily patterns of ac- tivities and their evolving social networks. The potential applications of such datasets include mapping patterns of information-flow within an organization, predicting the spread of disease within a commu- nity, monitoring the health and activity-levels of elderly patients as well as healthy adults, and allowing \"smart environments\" to respond proactively to the needs and intentions of their users.","Title: Mobile sensing: challenges, opportunities and future directions\nYear: 2011\n\nAbstract: The emerging field of mobile sensing has engaged computer scientists from a variety of existing communities, such as, mobile systems, machine learning and human computer interaction. Each community approaches the challenges of mobile sensing research with its own unique perspective. The purpose of this workshop is to provide a forum to discuss the state of the art in mobile sensing and promote increased cooperation and interaction among the participating research communities.","Title: A survey of mobile phone sensing\nYear: 2010\n\nAbstract: Mobile phones or smartphones are rapidly becoming the central computer and communication device in people's lives. Application delivery channels such as the Apple AppStore are transforming mobile phones into App Phones, capable of downloading a myriad of applications in an instant. Importantly, today's smartphones are programmable and come with a growing set of cheap powerful embedded sensors, such as an accelerometer, digital compass, gyroscope, GPS, microphone, and camera, which are enabling the emergence of personal, group, and community-scale sensing applications. We believe that sensor-equipped mobile phones will revolutionize many sectors of our economy, including business, health care, social networks, environmental monitoring, and transportation. In this article we survey existing mobile phone sensing algorithms, applications, and systems. We discuss the emerging sensing paradigms, and formulate an architectural framework for discussing a number of the open issues and challenges emerging in the new area of mobile phone sensing research.","Title: SoundSense: scalable sound sensing for people-centric applications on mobile phones\nYear: 2009\n\nAbstract: Top end mobile phones include a number of specialized (e.g., accelerometer, compass, GPS) and general purpose sensors (e.g., microphone, camera) that enable new people-centric sensing applications. Perhaps the most ubiquitous and unexploited sensor on mobile phones is the microphone - a powerful sensor that is capable of making sophisticated inferences about human activity, location, and social events from sound. In this paper, we exploit this untapped sensor not in the context of human communications but as an enabler of new sensing applications. We propose SoundSense, a scalable framework for modeling sound events on mobile phones. SoundSense is implemented on the Apple iPhone and represents the first general purpose sound sensing system specifically designed to work on resource limited phones. The architecture and algorithms are designed for scalability and Soundsense uses a combination of supervised and unsupervised learning techniques to classify both general sound types (e.g., music, voice) and discover novel sound events specific to individual users. The system runs solely on the mobile phone with no back-end interactions. Through implementation and evaluation of two proof of concept people-centric sensing applications, we demostrate that SoundSense is capable of recognizing meaningful sound events that occur in users' everyday lives.","Title: NeuroPhone: brain-mobile phone interface using a wireless EEG headset\nYear: 2010\n\nAbstract: Neural signals are everywhere just like mobile phones. We propose to use neural signals to control mobile phones for hands-free, silent and effortless human-mobile interaction. Until recently, devices for detecting neural signals have been costly, bulky and fragile. We present the design, implementation and evaluation of the NeuroPhone system, which allows neural signals to drive mobile phone applications on the iPhone using cheap off-the-shelf wireless electroencephalography (EEG) headsets. We demonstrate a brain-controlled address book dialing app, which works on similar principles to P300-speller brain-computer interfaces: the phone flashes a sequence of photos of contacts from the address book and a P300 brain potential is elicited when the flashed photo matches the person whom the user wishes to dial. EEG signals from the headset are transmitted wirelessly to an iPhone, which natively runs a lightweight classifier to discriminate P300 signals from noise. When a person's contact-photo triggers a P300, his/her phone number is automatically dialed. NeuroPhone breaks new ground as a brain-mobile phone interface for ubiquitous pervasive computing. We discuss the challenges in making our initial prototype more practical, robust, and reliable as part of our on-going research.","Title: Preference, context and communities: a multi-faceted approach to predicting smartphone app usage patterns\nYear: 2013\n\nAbstract: Reliable smartphone app prediction can strongly benefit both users and phone system performance alike. However, real-world smartphone app usage behavior is a complex phenomena driven by a number of competing factors. In this pa- per, we develop an app usage prediction model that leverages three key everyday factors that affect app usage decisions -- (1) intrinsic user app preferences and user historical patterns; (2) user activities and the environment as observed through sensor-based contextual signals; and, (3) the shared aggregate patterns of app behavior that appear in various user communities. While rapid progress has been made recently in smartphone app prediction, existing prediction models tend to focus on only one of these factors. We evaluate a multi-faceted approach to prediction using (1) a 3-week 35-user field trial, along with (2) analysis of app usage logs of 4,606 smartphone users worldwide. We find our app usage model can not only produce more robust app predictions than conventional techniques, but it can also enable significant smartphone system optimizations.","Title: Making Things Visible: Opportunities and Tensions in Visual Approaches for Design Research and Practice\nYear: 2014\n\nAbstract: Visual approaches for conducting research during the design process often give voice to people and ideas that might otherwise remain obscured. Recent and increasing interest in visual research techniques has coincided with technological advances such as camera phones and visually oriented mobile applications. As a result of this close association between digital technologies and image-based research techniques, there are multiple opportunities and challenges within human-computer interaction (HCI) design practice to employ these strategies to improve user experiences. This article provides an overview of current visual approaches to research highlighting the role technology has played in facilitating and inspiring these techniques. A series of case studies are presented that provide a basis for understanding a breadth of visual approaches in HCI design practices as well as serve as a point of entry to a critical and reflective discussion about the use of these approaches in different circumstances. Based on these reflections, three value statements are offered as a means to encourage the use of these visual approaches more broadly and critically in HCI design studies.","Title: BeWell: Sensing Sleep, Physical Activities and Social Interactions to Promote Wellbeing\nYear: 2014\n\nAbstract: Smartphone sensing and persuasive feedback design is enabling a new generation of wellbeing apps capable of automatically monitoring multiple aspects of physical and mental health. In this article, we present BeWell+ the next generation of the BeWell smartphone wellbeing app, which monitors user behavior along three health dimensions, namely sleep, physical activity, and social interaction. BeWell promotes improved behavioral patterns via feedback rendered as an ambient display on the smartphone's wallpaper. With BeWell+, we introduce new mechanisms to address key limitations of the original BeWell app; specifically, (1) community adaptive wellbeing feedback, which generalizes to diverse user communities (e.g., elderly, children) by promoting better behavior yet remains realistic to the user's lifestyle; and, (2) wellbeing adaptive energy allocation, which prioritizes monitoring fidelity and feedback responsiveness on specific health dimensions (e.g., sleep) where the user needs additional help. We evaluate BeWell+ with a 27 person, 19 day field trial. Our findings show that not only can BeWell+ operate successfully on consumer smartphones; but also users understand feedback and respond by taking steps towards leading healthier lifestyles.","Title: Towards circadian computing: \\\"early to bed and early to rise\\\" makes some of us unhealthy and sleep deprived\nYear: 2014\n\nAbstract: We often think of ourselves as individuals with steady capabilities. However, converging strands of research indicate that this is not the case. Our biochemistry varies significantly over the course of a 24 hour period. Consequently our levels of alertness, productivity, physical activity, and even sensitivity to pain fluctuate throughout the day. This offers a considerable opportunity for the UbiComp community to identify novel measurements and interventions that can leverage these daily variations. To illustrate this potential, we present results from an empirical study with 9 participants over 97 days investigating whether such variations manifest in low-level smartphone use, focusing on daily rhythms related to sleep. Our findings demonstrate that phone usage patterns can be used to detect and predict individual daily variations indicative of temporal preference, sleep duration, and deprivation. We also identify opportunities and challenges for measuring and enhancing well-being using these simple and effective markers of circadian rhythms.","Title: Towards personal stress informatics: comparing minimally invasive techniques for measuring daily stress in the wild\nYear: 2014\n\nAbstract: Identifying episodes of significant stress is a challenging problem with implications for personal health and interface adaptation. We present the results of a study comparing multiple modalities of minimally intrusive stress sensing in real-world environments, collected from seven participants as they carried out their everyday activities over a ten-day period. We compare the data streams produced by sensors and self-report measures, in addition to asking the participants, themselves, to reflect on the accuracy and completeness of the data that had been collected. Finally, we describe the range of participant experiences---both positive and negative---as they reported their everyday stress levels. As a result of this study, we demonstrate that voice-based stress sensing tracks with electrodermal activity and self-reported stress measures in real-world environments and we identify limitations of various sensing approaches.","Title: Towards accurate non-intrusive recollection of stress levels using mobile sensing and contextual recall\nYear: 2014\n\nAbstract: Existing user input sampling methods used for stress-related psychotherapy are plagued with problems of low recall accuracy and high intrusiveness. In this paper, we propose a contextual recall-based self-report method using mobile sensing technology that captures contextual cues including location, activity, and environmental acoustics to aid accurate recollection of stress levels. We conducted a controlled study with 36 participants. Our experimental results suggest that contextual recall outperforms recall-based self-report method by both increasing the recall accuracy and minimizing intrusiveness to participants at the same time. Moreover, we quantified the contribution of each individual contextual cue in recollecting stress levels. We found that although participants perceived all of the contextual cues to be useful, in reality, not all the contextual cues are weighted equally during the recollection process.","Title: Collective Smile: Measuring Societal Happiness from Geolocated Images\nYear: 2015\n\nAbstract: The increasing adoption of social media provides unprecedented opportunities to gain insight into human nature at vastly broader scales. Regarding the study of population-wide sentiment, prior research commonly focuses on text-based analyses and ignores a treasure trove of sentiment-laden content: images. In this paper, we make methodological and computational contributions by introducing the Smile Index as a formalized measure of societal happiness. Detecting smiles in 9 million geo-located tweets over 16 months, we validate our Smile Index against both text-based techniques and self-reported happiness. We further make observational contributions by applying our metric to explore temporal trends in sentiment, relate public mood to societal events, and predict economic indicators. Reflecting upon the innate, language-independent aspects of facial expressions, we recommend future improvements and applications to enable robust, global-level analyses. We conclude with implications for researchers studying and facilitating the expression of collective emotion through socio-technical systems.","Title: Boosting and structure learning in dynamic Bayesian networks for audio-visual speaker detection\nYear: 2002\n\nAbstract: Bayesian networks are an attractive modeling tool for human sensing, as they combine an intuitive graphical representation with efficient algorithms for inference and learning. Earlier work has demonstrated that boosted parameter learning could be used to improve the performance of Bayesian network, classifiers for complex multi-modal inference problems such as speaker detection. In speaker detection, the goal is to use video and audio cites to infer when a person is speaking to a user interface. In this paper we introduce a new boosted structure learning algorithm based on AdaBoost. Given labeled data, our algorithm modifies both the network structure and parameters so as to improve classification accuracy. We compare its performance to both standard structure learning and boosted parameter learning on a fixed structure. We present results for speaker detection and for the UCI \"chess\" dataset.","Title: Face recognition for smart environments\nYear: 2000\n\nAbstract: Smart environments, wearable computers, and ubiquitous computing in general are the coming “fourth generation” of computing and information technology. But that technology will be a stillbirth without new interfaces for interaction, minus a keyboard or mouse. To win wide consumer acceptance, these interactions must be friendly and personalized; the next generation interfaces must recognize people in their immediate environment and, at a minimum, know who they are. In this article, the authors discuss face recognition technology, how it works, problems to be overcome, current technologies, and future developments and possible applications. Twenty years ago, the problem of face recognition was considered among the most difficult in artificial intelligence and computer vision. Today, however, there are several companies that sell commercial face recognition software that is capable of high-accuracy recognition with databases of more than 1,000 people. The authors describe the face recognition technology used, explaining the algorithms for face recognition as well as novel applications, such as behavior monitoring that assesses emotions based on facial expressions","Title: Motion field histograms for robust modeling of facial expressions\nYear: 2000\n\nAbstract: This paper presents motion field histograms as a new way of extracting facial features and modeling expressions. Feature are based on local receptive field histograms, which are robust against errors in rotation, translation and scale changes during image alignment. Motion information is also incorporated into the histograms by using difference images instead of raw images. We take the principal com- ponents of these histograms of selected facial regions and use the top 20 eigenvectors for compact representation. The eigencoefficients are then used to model the temporal struc- ture of different facial expressions from real-life data in the presence of translational and rotational errors that arise from head-tracking. The results demonstrate a 44% aver- age performance increase over traditionaloptic flow method for expressions extracted from unconstrained interactions.","Title: Capturing Spontaneous Conversation and Social Dynamics: A Privacy-Sensitive Data Collection Effort\nYear: 2007\n\nAbstract: The UW Dynamic Social Network study is an effort to automatically observe and model the creation and evolution of a social network formed through spontaneous face-to-face conversations. We have collected more than 4,400 hours of data that capture the real world interactions between 24 subjects over a period of 9 months. The data was recorded in completely unconstrained and natural conditions, but was collected in a manner that protects the privacy of both study participants and non-participants. Despite the privacy constraints, the data allows for many different types of inference that are in turn useful for studying the prosodic and paralinguistic features of truly spontaneous speech across many subjects and over an extended pe- riod of time. This paper describes the new challenges and opportuni- ties presented in such a study, our data collection effort, the problems we encountered, and the resulting corpus. Index Terms—Data acquisition, privacy, speech analysis, oral communication","Title: Beyond Context Awareness\nYear: 2011\n\nAbstract: Much of the past pervasive computing research has been devoted to systems composed of a small number of devices that interact with a single individual or a small group of users. Body-worn sensors and sensors embedded in the user's environment were used to infer user location, activity, and information about the user's immediate surroundings, shaping the concept of context awareness. This issue is motivated by the fact that as technology becomes truly pervasive, we must proceed from the \"single user, single system\" perspective to \"large-scale heterogeneous systems\" involving many devices and many individuals collaborating over different spatial and temporal scales.","Title: From Smart to Cognitive Phones\nYear: 2012\n\nAbstract: As smartphones get smarter by pushing intelligence to the phone and computing cloud, they'll start to understand our life patterns, reason about our health and wellbeing, help us navigate our day, and intervene on our behalf. Here, the authors present various smartphone sensing systems that they've built, arguing that, eventually, these smartphones will evolve into cognitive phones.","Title: Model-Based Forecasting of Significant Societal Events\nYear: 2015\n\nAbstract: The article outlines some salient aspects of Embers-generated forecasts through its design considerations, system architecture, and user interface.","Title: Social (media) jet lag: how usage of social technology can modulate and reflect circadian rhythms\nYear: 2015\n\nAbstract: By nature, we are circadian creatures whose bodies' biological clocks drive numerous physiological, mental, and behavioral rhythms. Simultaneously, we are social beings. Accordingly, our internal circadian timings experience interference from externally determined factors such as work schedules and social engagements, and digital connectivity imports additional social constraints that can further misalign our individual body clocks. Misalignment between biological and social time causes social jet lag [50], which has serious physical and mental health consequences. It particularly impacts our sleep processes and neurobehavioral functioning. Examining the interplay between biological rhythms and technology-mediated social interactions, we find that technology may both modulate and reflect circadian rhythms. We also leverage such social-sensor data to infer sleep-related behaviors and disruptions and to analyze variations in attention, cognitive performance, and mood following (in)adequate sleep. We conclude with recommendations for designing technologies attuned to our innate biological traits.","Title: Mindless computing: designing technologies to subtly influence behavior\nYear: 2015\n\nAbstract: Persuasive technologies aim to influence user's behaviors. In order to be effective, many of the persuasive technologies developed so far relies on user's motivation and ability, which is highly variable and often the reason behind the failure of such technology. In this paper, we present the concept of Mindless Computing, which is a new approach to persuasive technology design. Mindless Computing leverages theories and concepts from psychology and behavioral economics into the design of technologies for behavior change. We show through a systematic review that most of the current persuasive technologies do not utilize the fast and automatic mental processes for behavioral change and there is an opportunity for persuasive technology designers to develop systems that are less reliant on user's motivation and ability. We describe two examples of mindless technologies and present pilot studies with encouraging results. Finally, we discuss design guidelines and considerations for developing this type of persuasive technology.","Title: DoppleSleep: a contactless unobtrusive sleep sensing system using short-range Doppler radar\nYear: 2015\n\nAbstract: In this paper, we present DoppleSleep -- a contactless sleep sensing system that continuously and unobtrusively tracks sleep quality using commercial off-the-shelf radar modules. DoppleSleep provides a single sensor solution to track sleep-related physical and physiological variables including coarse body movements and subtle and fine-grained chest, heart movements due to breathing and heartbeat. By integrating vital signals and body movement sensing, DoppleSleep achieves 89.6% recall with Sleep vs. Wake classification and 80.2% recall with REM vs. Non-REM classification compared to EEG-based sleep sensing. Lastly, it provides several objective sleep quality measurements including sleep onset latency, number of awakenings, and sleep efficiency. The contactless nature of DoppleSleep obviates the need to instrument the user's body with sensors. Lastly, DoppleSleep is implemented on an ARM microcontroller and a smartphone application that are benchmarked in terms of power and resource usage.","Title: Real time heart rate and breathing detection using commercial motion sensors\nYear: 2015\n\nAbstract: In this demo, we present a contactless breathing and heart rate sensing system that continuously and unobtrusively tracks physiological signals using commercial off-the-shelf radar modules. Our system provides a single sensor solution to track physical and physiological variables including coarse body movements as well as subtle and fine-grained chest movements due to breathing and heartbeat. Continuous tracking of these physiological variables especially, throughout the night can be used for sleep stage mining.","Title: MyBehavior: automatic personalized health feedback from user behaviors and preferences using smartphones\nYear: 2015\n\nAbstract: Mobile sensing systems have made significant advances in tracking human behavior. However, the development of personalized mobile health feedback systems is still in its infancy. This paper introduces MyBehavior, a smartphone application that takes a novel approach to generate deeply personalized health feedback. It combines state-of-the-art behavior tracking with algorithms that are used in recommendation systems. MyBehavior automatically learns a user's physical activity and dietary behavior and strategically suggests changes to those behaviors for a healthier lifestyle. The system uses a sequential decision making algorithm, Multi-armed Bandit, to generate suggestions that maximize calorie loss and are easy for the user to adopt. In addition, the system takes into account user's preferences to encourage adoption using the pareto-frontier algorithm. In a 14-week study, results show statistically significant increases in physical activity and decreases in food calorie when using MyBehavior compared to a control condition.","Title: An intelligent crowd-worker selection approach for reliable content labeling of food images\nYear: 2015\n\nAbstract: Food journaling is an effective way to regulate excessive food intake. However manual food journaling is burdensome, and crowd-assisted food journaling has been explored to ease user burden. The crowd-assisted journaling uses a label & verify approach where an end-user uploads his/her food image and paid crowd-workers label content of the image. Then another set of crowd-workers verify the labels for correctness. In this paper, we propose an alternative approach where we label food images with only high performing labelers. Since high performing labelers generally provide good quality labels, our approach achieves high accuracy without verifying the food labels for correctness. We also propose a machine learning algorithm to automatically identify high performing crowd-labelers from a dataset of 3925 images collected over 5 months. Such automated identification of high performing workers and elimination of needless verification reduce cost of food labeling. Specially for large scale deployments where large number of images need to be labeled, our approach can reduce overall expenses by half.","Title: Using smartphones to sense, assess, and improve well-being\nYear: 2014\n\nAbstract: The people-aware computing group at Cornell has been developing techniques to cheaply, accurately, and continuously collect data on daily human behavior, social interactions, and context. This data is subsequently leveraged to provide targeted, personalized and effective feedback to promote better mental and physical health in individuals. In this talk I will give an overview of our work on turning sensor-enabled mobile phones into well-being monitors and instruments for administering real-time/real-place interventions.","Title: In Situ Design for Mental Illness: Considering the Pathology of Bipolar Disorder in mHealth Design\nYear: 2015\n\nAbstract: In this paper, we argue that atypical cognitive, perceptual and behavioral characteristics associated with serious mental illnesses should be taken into consideration when designing health technologies. While applications have been developed to assist in the treatment of these illnesses, the specific psychological characteristics of these disorders have rarely been considered extensively in the design process. Here, we explore how an understanding of the low-level characteristics of bipolar disorder, combined with a clinically-validated treatment and patients' lived experience, can inform mHealth design. We present a novel method -- in situ design -- to support ecologically valid design, and demonstrate its use through the co-development with 9 individuals with bipolar disorder of MoodRhythm, a mobile application designed to track and stabilize daily routines. We provide evidence that mHealth design elements tailored to the characteristics and needs of individuals with bipolar disorder can result in engaging interactions.","Title: Automatic detection of social rhythms in bipolar disorder.\nYear: 2016\n\nAbstract: Objective To evaluate the feasibility of automatically assessing the Social Rhythm Metric (SRM), a clinically-validated marker of stability and rhythmicity for individuals with bipolar disorder (BD), using passively-sensed data from smartphones. Methods Seven patients with BD used smartphones for 4 weeks passively collecting sensor data including accelerometer, microphone, location, and communication information to infer behavioral and contextual patterns. Participants also completed SRM entries using a smartphone app. Results We found that automated sensing can be used to infer the SRM score. Using location, distance traveled, conversation frequency, and non-stationary duration as inputs, our generalized model achieves root-mean-square-error of 1.40, a reasonable performance given the range of SRM score (0-7). Personalized models further improve performance with mean root-mean-square-error of 0.92 across users. Classifiers using sensor streams can predict stable (SRM score >= 3.5) and unstable (SRM score <3.5) states with high accuracy (precision: 0.85 and recall: 0.86). Conclusions Automatic smartphone sensing is a feasible approach for inferring rhythmicity, a key marker of wellbeing for individuals with BD.","Title: EmotionCheck: leveraging bodily signals and false feedback to regulate our emotions.\nYear: 2016\n\nAbstract: In this paper we demonstrate that it is possible to help individuals regulate their emotions with mobile interventions that leverage the way we naturally react to our bodily signals. Previous studies demonstrate that the awareness of our bodily signals, such as our heart rate, directly influences the way we feel. By leveraging these findings we designed a wearable device to regulate user's anxiety by providing a false feedback of a slow heart rate. The results of an experiment with 67 participants show that the device kept the anxiety of the individuals in low levels when compared to the control group and the other conditions. We discuss the implications of our findings and present some promising directions for designing and developing this type of intervention for emotion regulation.","Title: Cognitive rhythms: unobtrusive and continuous sensing of alertness using a mobile phone.\nYear: 2016\n\nAbstract: Throughout the day, our alertness levels change and our cognitive performance fluctuates. The creation of technology that can adapt to such variations requires reliable measurement with ecological validity. Our study is the first to collect alertness data in the wild using the clinically validated Psychomotor Vigilance Test. With 20 participants over 40 days, we find that alertness can oscillate approximately 30% depending on time and body clock type and that Daylight Savings Time, hours slept, and stimulant intake can influence alertness as well. Based on these findings, we develop novel methods for unobtrusively and continuously assessing alertness. In estimating response time, our model achieves a root-mean-square error of 80.64 milliseconds, which is significantly lower than the 500ms threshold used as a standard indicator of impaired cognitive ability. Finally, we discuss how such real-time detection of alertness is a key first step towards developing systems that are sensitive to our biological variations.","Title: CrossCheck: toward passive sensing and detection of mental health changes in people with schizophrenia.\nYear: 2016\n\nAbstract: Early detection of mental health changes in individuals with serious mental illness is critical for effective intervention. CrossCheck is the first step towards the passive monitoring of mental health indicators in patients with schizophrenia and paves the way towards relapse prediction and early intervention. In this paper, we present initial results from an ongoing randomized control trial, where passive smartphone sensor data is collected from 21 outpatients with schizophrenia recently discharged from hospital over a period ranging from 2-8.5 months. Our results indicate that there are statistically significant associations between automatically tracked behavioral features related to sleep, mobility, conversations, smart-phone usage and self-reported indicators of mental health in schizophrenia. Using these features we build inference models capable of accurately predicting aggregated scores of mental health indicators in schizophrenia with a mean error of 7.6% of the score range. Finally, we discuss results on the level of personalization that is needed to account for the known variations within people. We show that by leveraging knowledge from a population with schizophrenia, it is possible to train accurate personalized models that require fewer individual-specific data to quickly adapt to new users.","Title: Assessing mental health issues on college campuses: preliminary findings from a pilot study.\nYear: 2016\n\nAbstract: A significant fraction of college students suffer from serious mental health issues including depression, anxiety, self-harm and suicidal thought. The prevalence and severity of these issues among college students also appear to increase over time. However, most of these issues often remain undiagnosed, and as a result, untreated. One of the main reasons of this gap between illness and treatment results from the lack of reliable data over time. While health care services in college campuses have been focusing on detection of illness onset and appropriate interventions, their tools are mostly manual surveys which often fail to capture the granular details of contexts and behaviors which might provide important cues about illness onset. To overcome the limitations of these manual tools, we deployed a smartphone based tool or unobtrusive and continuous data collection from 22 students during an academic semester. In this paper, we present the preliminary findings from our study about assessing mental health on college campuses using passively sensed smartphone data.","Title: Nutrilyzer: A Mobile System for Characterizing Liquid Food with Photoacoustic Effect.\nYear: 2016\n\nAbstract: In this paper, we propose Nutrilyzer, a novel mobile sensing system for characterizing the nutrients and detecting adulterants in liquid food with the photoacoustic effect. By listening to the sound of the intensity modulated light or electromagnetic wave with different wavelengths, our mobile photoacoustic sensing system captures unique spectra produced by the transmitted and scattered light while passing through various liquid food. As different liquid foods with different chemical compositions yield uniquely different spectral signatures, Nutrilyzer's signal processing and machine learning algorithm learn to map the photoacoustic signature to various liquid food characteristics including nutrients and adulterants. We evaluated Nutrilyzer for milk nutrient prediction (i.e., milk protein) and milk adulterant detection. We have also explored Nutrilyzer for alcohol concentration prediction. The Nutrilyzer mobile system consists of an array of 16 LEDs in ultraviolet, visible and near-infrared region, two piezoelectric sensors and an ARM microcontroller unit, which are designed and fabricated in a printed circuit board and a 3D printed photoacoustic housing.","Title: Mobile manifestations of alertness: connecting biological rhythms with patterns of smartphone app use.\nYear: 2016\n\nAbstract: Our body clock causes considerable variations in our behavioral, mental, and physical processes, including alertness, throughout the day. While much research has studied technology usage patterns, the potential impact of underlying biological processes on these patterns is under-explored. Using data from 20 participants over 40 days, this paper presents the first study to connect patterns of mobile application usage with these contributing biological factors. Among other results, we find that usage patterns vary for individuals with different body clock types, that usage correlates with rhythms of alertness, that app use features such as duration and switching can distinguish periods of low and high alertness, and that app use reflects sleep interruptions as well as sleep duration. We conclude by discussing how our findings inform the design of biologically-friendly technology that can better support personal rhythms of performance.","Title: Detecting And Capitalizing On Physiological Dimensions Of Psychiatric Illness\nYear: 2016\n\nAbstract: Serious mental illnesses, including bipolar disorders (BD), account for a large share of the worldwide healthcare burden-estimated at $62.7B in the U.S. alone. Bipolar disorders represent a family of common, lifelong illnesses associated with poor functional and clinical outcomes, high suicide rates, and huge societal costs. Interpersonal and Social Rhythm Therapy (IPSRT), a validated treatment for BD, helps patients lead lives characterized by greater stability of daily rhythms, using a 5 item paper-and-pencil self-monitoring instrument called the Social Rhythm Metric (SRM). IPSRT has been shown to improve patient outcomes, yet many patients struggle to monitor their daily routine or even access the treatment. In this paper we describe how biological characteristics of bipolar disorder can be taken into consideration when developing systems to detect and stabilize mood episodes. We describe the co-design of MoodRhythm, a smartphone and web app, with patients and therapists. It is designed to support patients in tracking their health passively and actively over a long period of time. MoodRhythm uses the phone's onboard sensors to automatically track sleep and social activity patterns. We report results of a small clinical pilot with experienced IPSRT clinicians and patients with bipolar disorder and finish by describing the role physiological computing could have not just in monitoring psychiatric illnesses according to existing broad categories of diagnosis but in helping radically tailor diagnoses to each individual patient and develop interventions that take advantage of idiosyncratic characteristics of each person's illness in order to increase patient engagement in and adherence to treatment.","Title: EmotionCheck: A Wearable Device to Regulate Anxiety through False Heart Rate Feedback\nYear: 2017\n\nAbstract: Previous studies indicate that the way we perceive our bodily signals, such as our heart rate, can influence how we feel. Inspired by these studies, we built EmotionCheck, which is a wearable device that can change users' perception of their heart rate through subtle vibrations on the wrist. The results of an experiment with 67 participants show that the EmotionCheck device can help users regulate their anxiety through false feedback of a slow heart rate.","Title: Sensing Technologies for Monitoring Serious Mental Illnesses.\nYear: 2018\n\nAbstract: Mental health is an urgent global issue. Around 450 million people suffer from serious mental illnesses worldwide, which results in devastating personal outcomes and huge societal burden. Effective symptom monitoring and personalized interventions can significantly improve mental health care across different populations. However, traditional clinical methods often fall short when it comes to real-...","Title: 3rd International Workshop on Mental Health and Well-being: Sensing and Intervention.\nYear: 2018\n\nAbstract: Mental health issues affect a significant portion of the world's population and can result in debilitating and life-threatening outcomes. To address this increasingly pressing healthcare challenge, there is a need to research novel approaches for early detection and prevention. Toward this, ubiquitous systems can play a central role in revealing and tracking clinically relevant behaviors, contexts, and symptoms. Further, such systems can passively detect relapse onset and enable the opportune delivery of effective intervention strategies. However, despite their clear potential, the uptake of ubiquitous technologies into clinical mental healthcare is rare, and a number of challenges still face the overall efficacy of such technology-based solutions. The goal of this workshop is to bring together researchers interested in identifying, articulating, and addressing such issues and opportunities. Following the success of this workshop in the last two years, we aim to continue facilitating the UbiComp community in developing a holistic approach for sensing and intervention in the context of mental health.","Title: A practical approach to recognizing physical activities\nYear: 2006\n\nAbstract: We are developing a personal activity recognition system that is practical, reliable, and can be incorporated into a variety of health-care related applications ranging from personal fitness to elder care. To make our system appealing and useful, we require it to have the following properties: (i) data only from a single body location needed, and it is not required to be from the same point for every user; (ii) should work out of the box across individuals, with personalization only enhancing its recognition abilities; and (iii) should be effective even with a cost-sensitive subset of the sensors and data features. In this paper, we present an approach to building a system that exhibits these properties and provide evidence based on data for 8 different activities collected from 12 different subjects. Our results indicate that the system has an accuracy rate of approximately 90% while meeting our requirements. We are now developing a fully embedded version of our system based on a cell-phone platform augmented with a Bluetooth-connected sensor board.","Title: Semi-Automated Tracking: A Balanced Approach for Self-Monitoring Applications\nYear: 2017\n\nAbstract: The authors present an approach for designing self-monitoring technology called \"semi-automated tracking,\" which combines both manual and automated data collection methods. Through this approach, they aim to lower the capture burdens, collect data that is typically hard to track automatically, and promote awareness to help people achieve their self-monitoring goals. They first specify three design considerations for semi-automated tracking: data capture feasibility, the purpose of self-monitoring, and the motivation level. They then provide examples of semi-automated tracking applications in the domains of sleep, mood, and food tracking to demonstrate strategies they developed to find the right balance between manual tracking and automated tracking, combining each of their benefits while minimizing their associated limitations.","Title: Regulating Feelings During Interpersonal Conflicts by Changing Voice Self-perception\nYear: 2018\n\nAbstract: ABSTRACTEmotions play a major role in how interpersonal conflicts unfold. Although several strategies and technological approaches have been proposed for emotion regulation, they often require conscious attention and effort. This often limits their efficacy in practice. In this paper, we propose a different approach inspired by self-perception theory: noticing that people are often reacting to the perception of their own behavior, we artificially change their perceptions to influence their emotions. We conducted two studies to evaluate the potential of this approach by automatically and subtly altering how people perceive their own voice. In one study, participants that received voice feedback with a calmer tone during relationship conflicts felt less anxious. In the other study, participants who listened to their own voices with a lower pitch during contentious debates felt more powerful. We discuss the implications of our findings and the opportunities for designing automatic and less perceptible emotion regulation systems.","Title: Personalized stress monitoring: a smartphone-enabled system for quantification of salivary cortisol.\nYear: 2018\n\nAbstract: Collection of salivary cortisol has been widely used as a method of investigating an array of health parameters. Monitoring of cortisol levels can help us to understand stress levels and the body’s response to stressors. Traditional methods of measuring cortisol in saliva, however, require costly equipment, trained personnel, and transportation of samples to a centralized laboratory. This creates a barrier to personal monitoring of cortisol. It also adds a level of cost and difficulty to large-scale studies which require participants to store and ship their saliva samples. Here, we present a novel system in which an individual with minimal training may collect their own saliva sample and measure it at home. Our system utilizes a lateral flow assay, a portable imaging device, and a smartphone to give salivary cortisol results in less than 15 min. We also demonstrate the use of our system on samples from a human study and give results from that study, which analyzes the relationship between cortisol levels and alertness across multiple days.","Title: Leveraging Multi-Modal Sensing for Mobile Health: A Case Review in Chronic Pain.\nYear: 2016\n\nAbstract: Active and passive mobile sensing has garnered much attention in recent years. In this paper, we focus on chronic pain measurement and management as a case application to exemplify the state of the art. We present a consolidated discussion on the leveraging of various sensing modalities along with modular server-side and on-device architectures required for this task. Modalities included are: acti...","Title: BoostMeUp: Improving Cognitive Performance in the Moment by Unobtrusively Regulating Emotions with a Smartwatch\nYear: 2019\n\nAbstract: A person's emotional state can strongly influence their ability to achieve optimal task performance. Aiming to help individuals manage their feelings, different emotion regulation technologies have been proposed. However, despite the well-known influence that emotions have on task performance, no study to date has shown if an emotion regulation technology can also enhance user's cognitive performance in the moment. In this paper, we present BoostMeUp, a smartwatch intervention designed to improve user's cognitive performance by regulating their emotions unobtrusively. Based on studies that show that people tend to associate external signals that resemble heart rates as their own, the intervention provides personalized haptic feedback simulating a different heart rate. Users can focus on their tasks and the intervention acts upon them in parallel, without requiring any additional action. The intervention was evaluated in an experiment with 72 participants, in which they had to do math tests under high pressure. Participants who were exposed to slow haptic feedback during the tests decreased their anxiety, increased their heart rate variability and performed better in the math tests, while fast haptic feedback led to the opposite effects. These results indicate that the BoostMeUp intervention can lead to positive cognitive, physiological and behavioral changes.","Title: Identifying Mobile Sensing Indicators of Stress-Resilience\nYear: 2021\n\nAbstract: AbstractResident physicians (residents) experiencing prolonged workplace stress are at risk of developing mental health symptoms. Creating novel, unobtrusive measures of resilience would provide an accessible approach to evaluate symptom susceptibility without the perceived stigma of formal mental health assessments. In this work, we created a system to find indicators of resilience using passive wearable sensors and smartphone-delivered ecological momentary assessment (EMA). This system identified indicators of resilience during a medical internship, the high stress first-year of a residency program. We then created density estimation approaches to predict these indicators before mental health changes occurred, and validated whether the predicted indicators were also associated with resilience. Our system identified resilience indicators associated with physical activity (step count), sleeping behavior, reduced heart rate, increased mood, and reduced mood variability. Density estimation models were able to replicate a subset of the associations between sleeping behavior, heart rate, and resilience. To the best of our knowledge, this work provides the first methodology to identify and predict indicators of resilience using passive sensing and EMA. Researchers studying resident mental health can apply this approach to design resilience-building interventions and prevent mental health symptom development.","Title: 6th International Workshop on Mental Health and Well-being: Sensing and Intervention\nYear: 2021\n\nAbstract: ABSTRACTMental health issues affect a significant portion of the world’s population and can result in debilitating and life-threatening outcomes. To address this increasingly pressing healthcare challenge, there is a need to research novel approaches for early detection and prevention. Toward this, ubiquitous systems can play a central role in revealing and tracking clinically relevant behaviors, contexts, and symptoms. Further, such systems can passively detect relapse onset and enable the opportune delivery of effective intervention strategies. However, despite their clear potential, the uptake of ubiquitous technologies into clinical mental healthcare is slow, and a number of challenges still face the overall efficacy of such technology-based solutions. The goal of this workshop is to bring together researchers interested in identifying, articulating, and addressing such issues and opportunities. Following the success of this workshop for the last five years, we aim to continue facilitating the UbiComp community in developing a holistic approach for sensing and intervention in the context of mental health."],"string":"[\n \"Title: Community Similarity Networks\\nYear: 2014\\n\\nAbstract: Sensor-enabled smartphones are opening a new frontier in the development of mobile sensing applications. The recognition of human activities and context from sensor data using classification models underpins these emerging applications. However, conventional approaches to training classifiers struggle to cope with the diverse user populations routinely found in large-scale popular mobile applications. Differences between users (e.g., age, sex, behavioral patterns, lifestyle) confuse classifiers, which assume everyone is the same. To address this, we propose Community Similarity Networks (CSN), which incorporates inter-person similarity measurements into the classifier training process. Under CSN, every user has a unique classifier that is tuned to their own characteristics. CSN exploits crowd-sourced sensor data to personalize classifiers with data contributed from other similar users. This process is guided by similarity networks that measure different dimensions of inter-person similarity. Our experiments show CSN outperforms existing approaches to classifier training under the presence of population diversity.\",\n \"Title: StressSense: detecting stress in unconstrained acoustic environments using smartphones\\nYear: 2012\\n\\nAbstract: Stress can have long term adverse effects on individuals' physical and mental well-being. Changes in the speech production process is one of many physiological changes that happen during stress. Microphones, embedded in mobile phones and carried ubiquitously by people, provide the opportunity to continuously and non-invasively monitor stress in real-life situations. We propose StressSense for unobtrusively recognizing stress from human voice using smartphones. We investigate methods for adapting a one-size-fits-all stress model to individual speakers and scenarios. We demonstrate that the StressSense classifier can robustly identify stress across multiple individuals in diverse acoustic environments: using model adaptation StressSense achieves 81% and 76% accuracy for indoor and outdoor environments, respectively. We show that StressSense can be implemented on commodity Android phones and run in real-time. To the best of our knowledge, StressSense represents the first system to consider voice based stress detection and model adaptation in diverse real-life conversational situations using smartphones.\",\n \"Title: Biological rhythms and technology\\nYear: 2014\\n\\nAbstract: Biological rhythms enable living organisms to adapt and live with periodical environmental changes, such as variation in the relative position of the earth and the sun. Internal rhythms, like body temperature and sleep-wake cycle, are driven by numerous biological processes and can be maintained even in the absence of external environmental cues. These rhythms affect how we feel, think, and act. They are profoundly important for our health, quality of sleep, and mood. Yet the digital devices we use are ignorant of our biology. They respond uniformly to our touch and click. Recently there has been a considerable increase of research within the HCI community to support behavior change, personal insight, and increase productivity. This workshop will bring together researchers in sleep, wellbeing, and circadian rhythms to discuss the possibility of rhythm systems: technologies that play to the strengths of our biology. It will investigate how HCI can complement our biological rhythms and will focus on two areas: measurement and intervention.\",\n \"Title: Activity-aware ECG-based patient authentication for remote health monitoring\\nYear: 2009\\n\\nAbstract: Mobile medical sensors promise to provide an efficient, accurate, and economic way to monitor patients' health outside the hospital. Patient authentication is a necessary security requirement in remote health monitoring scenarios. The monitoring system needs to make sure that the data is coming from the right person before any medical or financial decisions are made based on the data. Credential-based authentication methods (e.g., passwords, certificates) are not well-suited for remote healthcare as patients could hand over credentials to someone else. Furthermore, one-time authentication using credentials or trait-based biometrics (e.g., face, fingerprints, iris) do not cover the entire monitoring period and may lead to unauthorized post-authentication use. Recent studies have shown that the human electrocardiogram (ECG) exhibits unique patterns that can be used to discriminate individuals. However, perturbation of the ECG signal due to physical activity is a major obstacle in applying the technology in real-world situations. In this paper, we present a novel ECG and accelerometer-based system that can authenticate individuals in an ongoing manner under various activity conditions. We describe the probabilistic authentication system we have developed and present experimental results from 17 individuals.\",\n \"Title: Exploiting Social Networks for Large-Scale Human Behavior Modeling\\nYear: 2011\\n\\nAbstract: The Cooperative Communities (CoCo) learning framework leverages everyday social connections between people to personalize classification models. By exploiting social networks, CoCo spreads the burden of providing training data over an entire community.\",\n \"Title: Exploring Privacy Concerns about Personal Sensing\\nYear: 2009\\n\\nAbstract: More and more personal devices such as mobile phones and multimedia players use embedded sensing. This means that people are wearing and carrying devices capable of sensing details about them such as their activity, location, and environment. In this paper, we explore privacy concerns about such personal sensing through interviews with 24 participants who took part in a three month study that used personal sensing to detect their physical activities. Our results show that concerns often depended on what was being recorded, the context in which participants worked and lived and thus would be sensed, and the value they perceived would be provided. We suggest ways in which personal sensing can be made more privacy-sensitive to address these concerns.\",\n \"Title: MoodRhythm: tracking and supporting daily rhythms\\nYear: 2013\\n\\nAbstract: Rhythms guide our lives. Our biological clocks tell us when we need to sleep, eat and wake. But our use of technology can interrupt and obstruct these rhythms, making it difficult for our bodies to get what they need to stay healthy and balanced. Our MoodRhythm app helps individuals to live a more naturally rhythmic day. The key goals of MoodRhythm are to use patients' smartphones to actively and passively track daily rhythms and to provide affective feedback that can help patients to maintain a regular daily rhythm, while feeding this clinically valuable information back to their physicians.\",\n \"Title: A hybrid discriminative/generative approach for modeling human activities\\nYear: 2005\\n\\nAbstract: Accurate recognition and tracking of human activities is an important goal of ubiquitous computing. Recent advances in the development of multi-modal wearable sensors enable us to gather rich datasets of human activities. However, the problem of automatically identifying the most useful features for modeling such activities remains largely unsolved. In this paper we present a hybrid approach to recognizing activities, which combines boosting to discriminatively select useful features and learn an ensemble of static classifiers to recognize different activities, with hidden Markov models (HMMs) to capture the temporal regularities and smoothness of activities. We tested the activity recognition system using over 12 hours of wearable-sensor data collected by volunteers in natural unconstrained environments. The models succeeded in identifying a small set of maximally informative features, and were able identify ten different human activities with an accuracy of 95%.\",\n \"Title: Mobility detection using everyday GSM traces\\nYear: 2006\\n\\nAbstract: Recognition of everyday physical activities is difficult due to the challenges of building informative, yet unobtrusive sensors. The most widely deployed and used mobile computing device today is the mobile phone, which presents an obvious candidate for recognizing activities. This paper explores how coarse-grained GSM data from mobile phones can be used to recognize high-level properties of user mobility, and daily step count. We demonstrate that even without knowledge of observed cell tower locations, we can recognize mobility modes that are useful for several application domains. Our mobility detection system was evaluated with GSM traces from the everyday lives of three data collectors over a period of one month, yielding an overall average accuracy of 85%, and a daily step count number that reasonably approximates the numbers determined by several commercial pedometers.\",\n \"Title: Building reliable activity models using hierarchical shrinkage and mined ontology\\nYear: 2006\\n\\nAbstract: Activity inference based on object use has received considerable recent attention. Such inference requires statistical models that map activities to the objects used in performing them. Proposed techniques for constructing these models (hand definition, learning from data, and web extraction) all share the problem of model incompleteness: it is difficult to either manually or automatically identify all the possible objects that may be used to perform an activity, or to accurately calculate the probability with which they will be used. In this paper, we show how to use auxiliary information, called an ontology, about the functional similarities between objects to mitigate the problem of model incompleteness. We show how to extract a large, relevant ontology automatically from WordNet, an online lexical reference system for the English language. We adapt a statistical smoothing technique, called shrinkage, to apply this similarity information to counter the incompleteness of our models. Our results highlight two advantages of performing shrinkage. First, overall activity recognition accuracy improves by 15.11% by including the ontology to re-estimate the parameters of models that are automatically mined from the web. Shrinkage can therefore serve as a technique for making web-mined activity models more attractive. Second, smoothing yields an increased recognition accuracy when objects not present in the incomplete models are used while performing an activity. When we replace 100% of the objects with other objects that are functionally similar, we get an accuracy drop of only 33% when using shrinkage as opposed to 91.66% (equivalent to random guessing) without shrinkage. If training data is available, shrinkage further improves classification accuracy.\",\n \"Title: Modeling Conversational Dynamics as a Mixed-Memory Markov Process\\nYear: 2004\\n\\nAbstract: In this work, we quantitatively investigate the ways in which a given person influences the joint turn-taking behavior in a conversation. After collecting an auditory database of social interactions among a group of twenty-three people via wearable sensors (66 hours of data each over two weeks), we apply speech and conversation detection methods to the auditory streams. These methods automatically locate the conversations, determine their participants, and mark which participant was speaking when. We then model the joint turn-taking behavior as a Mixed-Memory Markov Model (1) that combines the statistics of the individual subjects' self-transitions and the partners' cross-transitions. The mixture parameters in this model describe how much each person's individual behavior contributes to the joint turn-taking behavior of the pair. By estimating these parameters, we thus estimate how much influence each participant has in determining the joint turn- taking behavior. We show how this measure correlates significantly with betweenness centrality (2), an independent measure of an individual's importance in a social network. This result suggests that our estimate of conversational influence is predictive of social influence.\",\n \"Title: Human dynamics: computation for organizations: Human dynamics: computation for organizations\\nYear: 2005\\n\\nAbstract: The human dynamics group at the MIT Media Laboratory proposes that active pattern analysis of face-to-face interactions within the workplace can radically improve the functioning of the organization. There are several different types of information inherent in such conversations: interaction features, participants, context, and content. By aggregating this information, high-potential collaborations and expertise within the organization can be identified, and information efficiently distributed. Examples of using wearable machine perception to characterize face-to-face interactions and using the results to initiate productive connections are described, and privacy concerns are addressed.\",\n \"Title: BeWell+: multi-dimensional wellbeing monitoring with community-guided user feedback and energy optimization\\nYear: 2012\\n\\nAbstract: Smartphone sensing and persuasive feedback design is enabling a new generation of wellbeing applications capable of automatically monitoring multiple aspects of physical and mental health. In this paper, we present BeWell+ the next generation of the BeWell smartphone health app, which continuously monitors user behavior along three distinct health dimensions, namely sleep, physical activity, and social interaction. BeWell promotes improved behavioral patterns via feedback rendered as an ambient display on the smartphone's wallpaper. With BeWell+, we introduce new wellbeing mechanisms to address challenges identified during the initial deployment of the BeWell app; specifically, (i) community adaptive wellbeing feedback, which automatically generalize to diverse user communities (e.g., elderly, young adults, children) by balancing the need to promote better behavior yet remains realistic to the user's goals; and, (ii) wellbeing adaptive energy allocation, which prioritizes monitoring fidelity and feedback responsiveness on specific health dimensions of wellbeing (e.g., social interaction) where the user needs most help. We evaluate the performance of these mechanisms as part of an initial deployment and user study that includes 27 people using BeWell+ over a 19 day field trial. Our findings show that not only can BeWell+ operate successfully on consumer-grade smartphones, but users understand feedback and respond by taking positive steps towards leading healthier lifestyles.\",\n \"Title: Tracking Mental Well-Being: Balancing Rich Sensing and Patient Needs\\nYear: 2014\\n\\nAbstract: Serious mental illnesses are among the most pressing public healthcare concerns. Continuous and unobtrusive sensing of social and physical functioning has tremendous potential to support lifelong health management by acting as an early warning system to detect changes in mental well-being, delivering context-aware micro-interventions to patients when and where they need them and significantly accelerating patients' understanding of their illness.\",\n \"Title: Learning hidden curved exponential family models to infer face-to-face interaction networks from situated speech data\\nYear: 2008\\n\\nAbstract: In this paper, we present a novel probabilistic framework for recovering global, latent social network structure from local, noisy observations. We extend curved exponential random graph models to include two types of variables: hidden variables that capture the structure of the network and observational variables that capture the behavior between actors in the network. We develop a novel combination of informative and intuitive conversational (local) and structural (global) features to specify our model. The model learns, in an unsupervised manner, the relationship between observable behavior and hidden social structure while simultaneously learning properties of the latent structure itself. We present empirical results on both synthetic data and a real world dataset of face-to-face conversations collected from 24 individuals using wearable sensors over the course of 6 months.\",\n \"Title: Inferring colocation and conversation networks from privacy-sensitive audio with implications for computational social science\\nYear: 2011\\n\\nAbstract: New technologies have made it possible to collect information about social networks as they are acted and observed in the wild, instead of as they are reported in retrospective surveys. These technologies offer opportunities to address many new research questions: How can meaningful information about social interaction be extracted from automatically recorded raw data on human behavior? What can we learn about social networks from such fine-grained behavioral data? And how can all of this be done while protecting privacy? With the goal of addressing these questions, this article presents new methods for inferring colocation and conversation networks from privacy-sensitive audio. These methods are applied in a study of face-to-face interactions among 24 students in a graduate school cohort during an academic year. The resulting analysis shows that networks derived from colocation and conversation inferences are quite different. This distinction can inform future research in computational social science, especially work that only measures colocation or employs colocation data as a proxy for conversation networks.\",\n \"Title: Technology Development for Building Flexible Silicon Functional Fibres\\nYear: 2003\\n\\nAbstract: Most of everyday clothing consists of textile fibres woventogether to produce a fabric.Their primary purpose isstructural and aesthetic. Fibres can have added functionalityby the integration of computing power into the material thatforms them. The purpose of the 'fibre computing' concept is tointegrate this new dimension of functionality into fibres, thusturning everyday clothing objects into intelligent artefacts.\",\n \"Title: A Scalable Approach to Activity Recognition based on Object Use\\nYear: 2007\\n\\nAbstract: We propose an approach to activity recognition based on detecting and analyzing the sequence of objects that are being manipulated by the user. In domains such as cooking, where many activities involve similar actions, object-use information can be a valuable cue. In order for this approach to scale to many activities and objects, however, it is necessary to minimize the amount of human-labeled data that is required for modeling. We describe a method for automatically acquiring object models from video without any explicit human supervision. Our approach leverages sparse and noisy readings from RFID tagged objects, along with common-sense knowledge about which objects are likely to be used during a given activity, to bootstrap the learning process. We present a dynamic Bayesian network model which combines RFID and video data to jointly infer the most likely activity and object labels. We demonstrate that our approach can achieve activity recognition rates of more than 80% on a real-world dataset consisting of 16 household activities involving 33 objects with significant background clutter. We show that the combination of visual object recognition with RFID data is significantly more effective than the RFID sensor alone. Our work demonstrates that it is possible to automatically learn object models from video of household activities and employ these models for activity recognition, without requiring any explicit human labeling.\",\n \"Title: Common sense based joint training of human activity recognizers\\nYear: 2007\\n\\nAbstract: Given sensors to detect object use, commonsense priors of object usage in activities can reduce the need for labeled data in learning activity models. It is often useful, however, to understand how an object is being used, i.e., the action performed on it. We show how to add personal sensor data (e.g., accelerometers) to obtain this detail, with little labeling and feature selection overhead. By synchronizing the personal sensor data with object-use data, it is possible to use easily specified commonsense models to minimize labeling overhead. Further, combining a generative common sense model of activity with a discriminative model of actions can automate feature selection. On observed activity data, automatically trained action classifiers give 40/85% precision/recall on 10 actions. Adding actions to pure object-use improves precision/recall from 76/85% to 81/90% over 12 activities.\",\n \"Title: Unsupervised activity recognition using automatically mined common sense\\nYear: 2005\\n\\nAbstract: A fundamental difficulty in recognizing human activities is obtaining the labeled data needed to learn models of those activities. Given emerging sensor technology, however, it is possible to view activity data as a stream of natural language terms. Activity models are then mappings from such terms to activity names, and may be extracted from text corpora such as the web. We show that models so extracted are sufficient to automatically produce labeled segmentations of activity data with an accuracy of 42% over 26 activities, well above the 3.89% baseline. The segmentation so obtained is sufficient to bootstrap learning, with accuracy of learned models increasing to 52%. To our knowledge, this is the first human activity inferencing system shown to learn from sensed activity data with no human intervention per activity learned, even for labeling.\",\n \"Title: BodyBeat: a mobile system for sensing non-speech body sounds\\nYear: 2014\\n\\nAbstract: In this paper, we propose BodyBeat, a novel mobile sensing system for capturing and recognizing a diverse range of non-speech body sounds in real-life scenarios. Non-speech body sounds, such as sounds of food intake, breath, laughter, and cough contain invaluable information about our dietary behavior, respiratory physiology, and affect. The BodyBeat mobile sensing system consists of a custom-built piezoelectric microphone and a distributed computational framework that utilizes an ARM microcontroller and an Android smartphone. The custom-built microphone is designed to capture subtle body vibrations directly from the body surface without being perturbed by external sounds. The microphone is attached to a 3D printed neckpiece with a suspension mechanism. The ARM embedded system and the Android smartphone process the acoustic signal from the microphone and identify non-speech body sounds. We have extensively evaluated the BodyBeat mobile sensing system. Our results show that BodyBeat outperforms other existing solutions in capturing and recognizing different types of important non-speech body sounds.\",\n \"Title: Fast and Scalable Training of Semi-Supervised CRFs with Application to Activity Recognition\\nYear: 2007\\n\\nAbstract: We present a new and efficient semi-supervised training method for parameter es- timation and feature selection in conditional random fields (CRFs). In real-world applications such as activity recognition, unlabeled sensor traces are relatively easy to obtain whereas labeled examples are expensive and tedious to collect. Furthermore, the ability to automatically select a small subset of discriminatory features from a large pool can be advantageous in terms of computational speed as well as accuracy. In this paper, we introduce the semi-supervised virtual evidence boosting (sVEB) algorithm for training CRFs - a semi-supervised extension to the recently developed virtual evidence boosting (VEB) method for feature selection and parameter learning. The objective function of sVEB combines the unlabeled conditional entropy with labeled conditional pseudo-likelihood. It reduces the overall system cost as well as the human labeling cost required during training, which are both important considerations in building real-world inference systems. Experiments on synthetic data and real activity traces collected from wearable sensors, illustrate that sVEB benefits from both the use of unlabeled data and au- tomatic feature selection, and outperforms other semi-supervised approaches.\",\n \"Title: The Jigsaw continuous sensing engine for mobile phone applications\\nYear: 2010\\n\\nAbstract: Supporting continuous sensing applications on mobile phones is challenging because of the resource demands of long-term sensing, inference and communication algorithms. We present the design, implementation and evaluation of the Jigsaw continuous sensing engine, which balances the performance needs of the application and the resource demands of continuous sensing on the phone. Jigsaw comprises a set of sensing pipelines for the accelerometer, microphone and GPS sensors, which are built in a plug and play manner to support: i) resilient accelerometer data processing, which allows inferences to be robust to different phone hardware, orientation and body positions; ii) smart admission control and on-demand processing for the microphone and accelerometer data, which adaptively throttles the depth and sophistication of sensing pipelines when the input data is low quality or uninformative; and iii) adaptive pipeline processing, which judiciously triggers power hungry pipeline stages (e.g., sampling the GPS) taking into account the mobility and behavioral patterns of the user to drive down energy costs. We implement and evaluate Jigsaw on the Nokia N95 and the Apple iPhone, two popular smartphone platforms, to demonstrate its capability to recognize user activities and perform long term GPS tracking in an energy-efficient manner.\",\n \"Title: Unobtrusive sleep monitoring using smartphones\\nYear: 2013\\n\\nAbstract: How we feel is greatly influenced by how well we sleep. Emerging quantified-self apps and wearable devices allow people to measure and keep track of sleep duration, patterns and quality. However, these approaches are intrusive, placing a burden on the users to modify their daily sleep related habits in order to gain sleep data; for example, users have to wear cumbersome devices (e.g., a headband) or inform the app when they go to sleep and wake up. In this paper, we present a radically different approach for measuring sleep duration based on a novel best effort sleep (BES) model. BES infers sleep using smartphones in a completely unobtrusive way - that is, the user is completely removed from the monitoring process and does not interact with the phone beyond normal user behavior. A sensor-based inference algorithm predicts sleep duration by exploiting a collection of soft hints that tie sleep duration to various smartphone usage patterns (e.g., the time and length of smartphone usage or recharge events) and environmental observations (e.g., prolonged silence and darkness). We perform quantitative and qualitative comparisons between two smartphone only approaches that we developed (i.e., BES model and a sleep-with-the-phone approach) and two popular commercial wearable systems (Le., the Zeo headband and Jawbone wristband). Results from our one-week 8-person study look very promising and show that the BES model can accurately infer sleep duration (± 42 minutes) using a completely \\\"hands off\\\" approach that can cope with the natural variation in users' sleep routines and environments.\",\n \"Title: Darwin phones: the evolution of sensing and inference on mobile phones\\nYear: 2010\\n\\nAbstract: We present Darwin, an enabling technology for mobile phone sensing that combines collaborative sensing and classification techniques to reason about human behavior and context on mobile phones. Darwin advances mobile phone sensing through the deployment of efficient but sophisticated machine learning techniques specifically designed to run directly on sensor-enabled mobile phones (i.e., smartphones). Darwin tackles three key sensing and inference challenges that are barriers to mass-scale adoption of mobile phone sensing applications: (i) the human-burden of training classifiers, (ii) the ability to perform reliably in different environments (e.g., indoor, outdoor) and (iii) the ability to scale to a large number of phones without jeopardizing the \\\"phone experience\\\" (e.g., usability and battery lifetime). Darwin is a collaborative reasoning framework built on three concepts: classifier/model evolution, model pooling, and collaborative inference. To the best of our knowledge Darwin is the first system that applies distributed machine learning techniques and collaborative inference concepts to mobile phones. We implement the Darwin system on the Nokia N97 and Apple iPhone. While Darwin represents a general framework applicable to a wide variety of emerging mobile sensing applications, we implement a speaker recognition application and an augmented reality application to evaluate the benefits of Darwin. We show experimental results from eight individuals carrying Nokia N97s and demonstrate that Darwin improves the reliability and scalability of the proof-of-concept speaker recognition application without additional burden to users.\",\n \"Title: Sensing and Modeling Human Networks using the Sociometer\\nYear: 2003\\n\\nAbstract: Knowledge of how people interact is important in manydisciplines, e.g. organizational behavior, social networkanalysis, information diffusion and knowledge managementapplications. We are developing methods to automaticallyand unobtrusively learn the social network structures thatarise within human groups based on wearable sensors. Atpresent researchers mainly have to rely on questionnaires,surveys or diaries in order to obtain data on physicalinteractions between people. In this paper, we show howsensor measurements from the sociometer can be used tobuild computational models of group interactions. Wepresent results on how we can learn the structure of face-to-face interactions within groups, detect when membersare in face-to-face proximity and also when they are havinga conversation.\",\n \"Title: Passive and In-situ Assessment of Mental and Physical Well-being using Mobile Sensors.\\nYear: 2011\\n\\nAbstract: The idea of continuously monitoring well-being using mobile-sensing systems is gaining popularity. In-situ measurement of human behavior has the potential to overcome the short comings of gold-standard surveys that have been used for decades by the medical community. However, current sensing systems have mainly focused on tracking physical health; some have approximated aspects of mental health based on proximity measurements but have not been compared against medically accepted screening instruments. In this paper, we show the feasibility of a multi-modal mobile sensing system to simultaneously assess mental and physical health. By continuously capturing fine grained motion and privacy-sensitive audio data, we are able to derive different metrics that reflect the results of commonly used surveys for assessing well-being by the medical community. In addition, we present a case study that highlights how errors in assessment due to the subjective nature of the responses could potentially be avoided by continuous sensing and inference of social interactions and physical activities.\",\n \"Title: Training conditional random fields using virtual evidence boosting\\nYear: 2007\\n\\nAbstract: While conditional random fields (CRFs) have been applied successfully in a variety of domains, their training remains a challenging task. In this paper, we introduce a novel training method for CRFs, called virtual evidence boosting, which simultaneously performs feature selection and parameter estimation. To achieve this, we extend standard boosting to handle virtual evidence, where an observation can be specified as a distribution rather than a single number. This extension allows us to develop a unified framework for learning both local and compatibility features in CRFs. In experiments on synthetic data as well as real activity classification problems, our new training algorithm outperforms other training approaches including maximum likelihood, maximum pseudo-likelihood, and the most recent boosted random fields.\",\n \"Title: The Mobile Sensing Platform: An Embedded Activity Recognition System\\nYear: 2008\\n\\nAbstract: The Mobile Sensing Platform (MSP) is a small-form-factor wearable device designed for embedded activity recognition. The MSP aims broadly to support context-aware ubiquitous computing applications. It incorporates multimodal sensing, data processing and inference, storage, all-day battery life, and wireless connectivity into a single 4 oz (115 g) wearable unit. Several design iterations and real-world deployments over the last four years have identified a set of core hardware and software requirements for a mobile inference system. This article presents findings and lessons learned in the course of designing, improving and using this system. This article is part of a special issue on activity-based computing.\",\n \"Title: Enabling large-scale human activity inference on smartphones using community similarity networks (csn)\\nYear: 2011\\n\\nAbstract: Sensor-enabled smartphones are opening a new frontier in the development of mobile sensing applications. The recognition of human activities and context from sensor-data using classification models underpins these emerging applications. However, conventional approaches to training classifiers struggle to cope with the diverse user populations routinely found in large-scale popular mobile applications. Differences between users (e.g., age, sex, behavioral patterns, lifestyle) confuse classifiers, which assume everyone is the same. To address this, we propose Community Similarity Networks (CSN), which incorporates inter-person similarity measurements into the classifier training process. Under CSN every user has a unique classifier that is tuned to their own characteristics. CSN exploits crowd-sourced sensor-data to personalize classifiers with data contributed from other similar users. This process is guided by similarity networks that measure different dimensions of inter-person similarity. Our experiments show CSN outperforms existing approaches to classifier training under the presence of population diversity.\",\n \"Title: A privacy-sensitive approach to modeling multi-person conversations\\nYear: 2007\\n\\nAbstract: In this paper we introduce a new dynamic Bayesian network that separates the speakers and their speaking turns in a multi-person conversation. We protect the speakers' privacy by using only features from which intelligible speech cannot be reconstructed. The model we present combines data from multiple audio streams, segments the streams into speech and silence, separates the different speakers, and detects when other nearby individuals who are not wearing microphones are speaking. No pre-trained speaker specific models are used, so the system can be easily applied in new and different environments. We show promising results in two very different datasets that vary in background noise, microphone placement and quality, and conversational dynamics.\",\n \"Title: Towards the automated social analysis of situated speech data\\nYear: 2008\\n\\nAbstract: We present an automated approach for studying fine-grained details of social interaction and relationships. Specifically, we analyze the conversational characteristics of a group of 24 individuals over a six-month period, explore the relationship between conversational dynamics and network position, and identify behavioral correlates of tie strengths within a network. The ability to study conversational dynamics and social networks over long time scales, and to investigate their interplay with rigor, objectivity, and transparency will complement the traditional methods for scientific inquiry into social dynamics. They may also enable socially aware ubiquitous computing systems that are cognizant of and responsive to the user's engagement with her social environment.\",\n \"Title: Towards Activity Databases: Using Sensors and Statistical Models to Summarize People's Lives\\nYear: 2006\\n\\nAbstract: Automated reasoning about human behavior is a central goal of artificial intelligence. In order to engage and intervene in a meaningful way, an intelligent system must be able to understand what hu- mans are doing, their goals and intentions. Furthermore, as social animals, people's interactions with each other underlie many aspects of their lives: how they learn, how they work, how they play and how they affect the broader community. Understanding people's interactions and their social networks will play an important role in designing technology and applications that are \\\"socially-aware\\\". This paper introduces some of the current approaches in activity recognition which use a variety of different sensors to collect data about users' activities, and probabilistic models and relational information that are used to transform the raw sensor data into higher-level descriptions of people's behaviors and interactions. The end result of these methods is a richly structured dataset describing people's daily patterns of ac- tivities and their evolving social networks. The potential applications of such datasets include mapping patterns of information-flow within an organization, predicting the spread of disease within a commu- nity, monitoring the health and activity-levels of elderly patients as well as healthy adults, and allowing \\\"smart environments\\\" to respond proactively to the needs and intentions of their users.\",\n \"Title: Mobile sensing: challenges, opportunities and future directions\\nYear: 2011\\n\\nAbstract: The emerging field of mobile sensing has engaged computer scientists from a variety of existing communities, such as, mobile systems, machine learning and human computer interaction. Each community approaches the challenges of mobile sensing research with its own unique perspective. The purpose of this workshop is to provide a forum to discuss the state of the art in mobile sensing and promote increased cooperation and interaction among the participating research communities.\",\n \"Title: A survey of mobile phone sensing\\nYear: 2010\\n\\nAbstract: Mobile phones or smartphones are rapidly becoming the central computer and communication device in people's lives. Application delivery channels such as the Apple AppStore are transforming mobile phones into App Phones, capable of downloading a myriad of applications in an instant. Importantly, today's smartphones are programmable and come with a growing set of cheap powerful embedded sensors, such as an accelerometer, digital compass, gyroscope, GPS, microphone, and camera, which are enabling the emergence of personal, group, and community-scale sensing applications. We believe that sensor-equipped mobile phones will revolutionize many sectors of our economy, including business, health care, social networks, environmental monitoring, and transportation. In this article we survey existing mobile phone sensing algorithms, applications, and systems. We discuss the emerging sensing paradigms, and formulate an architectural framework for discussing a number of the open issues and challenges emerging in the new area of mobile phone sensing research.\",\n \"Title: SoundSense: scalable sound sensing for people-centric applications on mobile phones\\nYear: 2009\\n\\nAbstract: Top end mobile phones include a number of specialized (e.g., accelerometer, compass, GPS) and general purpose sensors (e.g., microphone, camera) that enable new people-centric sensing applications. Perhaps the most ubiquitous and unexploited sensor on mobile phones is the microphone - a powerful sensor that is capable of making sophisticated inferences about human activity, location, and social events from sound. In this paper, we exploit this untapped sensor not in the context of human communications but as an enabler of new sensing applications. We propose SoundSense, a scalable framework for modeling sound events on mobile phones. SoundSense is implemented on the Apple iPhone and represents the first general purpose sound sensing system specifically designed to work on resource limited phones. The architecture and algorithms are designed for scalability and Soundsense uses a combination of supervised and unsupervised learning techniques to classify both general sound types (e.g., music, voice) and discover novel sound events specific to individual users. The system runs solely on the mobile phone with no back-end interactions. Through implementation and evaluation of two proof of concept people-centric sensing applications, we demostrate that SoundSense is capable of recognizing meaningful sound events that occur in users' everyday lives.\",\n \"Title: NeuroPhone: brain-mobile phone interface using a wireless EEG headset\\nYear: 2010\\n\\nAbstract: Neural signals are everywhere just like mobile phones. We propose to use neural signals to control mobile phones for hands-free, silent and effortless human-mobile interaction. Until recently, devices for detecting neural signals have been costly, bulky and fragile. We present the design, implementation and evaluation of the NeuroPhone system, which allows neural signals to drive mobile phone applications on the iPhone using cheap off-the-shelf wireless electroencephalography (EEG) headsets. We demonstrate a brain-controlled address book dialing app, which works on similar principles to P300-speller brain-computer interfaces: the phone flashes a sequence of photos of contacts from the address book and a P300 brain potential is elicited when the flashed photo matches the person whom the user wishes to dial. EEG signals from the headset are transmitted wirelessly to an iPhone, which natively runs a lightweight classifier to discriminate P300 signals from noise. When a person's contact-photo triggers a P300, his/her phone number is automatically dialed. NeuroPhone breaks new ground as a brain-mobile phone interface for ubiquitous pervasive computing. We discuss the challenges in making our initial prototype more practical, robust, and reliable as part of our on-going research.\",\n \"Title: Preference, context and communities: a multi-faceted approach to predicting smartphone app usage patterns\\nYear: 2013\\n\\nAbstract: Reliable smartphone app prediction can strongly benefit both users and phone system performance alike. However, real-world smartphone app usage behavior is a complex phenomena driven by a number of competing factors. In this pa- per, we develop an app usage prediction model that leverages three key everyday factors that affect app usage decisions -- (1) intrinsic user app preferences and user historical patterns; (2) user activities and the environment as observed through sensor-based contextual signals; and, (3) the shared aggregate patterns of app behavior that appear in various user communities. While rapid progress has been made recently in smartphone app prediction, existing prediction models tend to focus on only one of these factors. We evaluate a multi-faceted approach to prediction using (1) a 3-week 35-user field trial, along with (2) analysis of app usage logs of 4,606 smartphone users worldwide. We find our app usage model can not only produce more robust app predictions than conventional techniques, but it can also enable significant smartphone system optimizations.\",\n \"Title: Making Things Visible: Opportunities and Tensions in Visual Approaches for Design Research and Practice\\nYear: 2014\\n\\nAbstract: Visual approaches for conducting research during the design process often give voice to people and ideas that might otherwise remain obscured. Recent and increasing interest in visual research techniques has coincided with technological advances such as camera phones and visually oriented mobile applications. As a result of this close association between digital technologies and image-based research techniques, there are multiple opportunities and challenges within human-computer interaction (HCI) design practice to employ these strategies to improve user experiences. This article provides an overview of current visual approaches to research highlighting the role technology has played in facilitating and inspiring these techniques. A series of case studies are presented that provide a basis for understanding a breadth of visual approaches in HCI design practices as well as serve as a point of entry to a critical and reflective discussion about the use of these approaches in different circumstances. Based on these reflections, three value statements are offered as a means to encourage the use of these visual approaches more broadly and critically in HCI design studies.\",\n \"Title: BeWell: Sensing Sleep, Physical Activities and Social Interactions to Promote Wellbeing\\nYear: 2014\\n\\nAbstract: Smartphone sensing and persuasive feedback design is enabling a new generation of wellbeing apps capable of automatically monitoring multiple aspects of physical and mental health. In this article, we present BeWell+ the next generation of the BeWell smartphone wellbeing app, which monitors user behavior along three health dimensions, namely sleep, physical activity, and social interaction. BeWell promotes improved behavioral patterns via feedback rendered as an ambient display on the smartphone's wallpaper. With BeWell+, we introduce new mechanisms to address key limitations of the original BeWell app; specifically, (1) community adaptive wellbeing feedback, which generalizes to diverse user communities (e.g., elderly, children) by promoting better behavior yet remains realistic to the user's lifestyle; and, (2) wellbeing adaptive energy allocation, which prioritizes monitoring fidelity and feedback responsiveness on specific health dimensions (e.g., sleep) where the user needs additional help. We evaluate BeWell+ with a 27 person, 19 day field trial. Our findings show that not only can BeWell+ operate successfully on consumer smartphones; but also users understand feedback and respond by taking steps towards leading healthier lifestyles.\",\n \"Title: Towards circadian computing: \\\\\\\"early to bed and early to rise\\\\\\\" makes some of us unhealthy and sleep deprived\\nYear: 2014\\n\\nAbstract: We often think of ourselves as individuals with steady capabilities. However, converging strands of research indicate that this is not the case. Our biochemistry varies significantly over the course of a 24 hour period. Consequently our levels of alertness, productivity, physical activity, and even sensitivity to pain fluctuate throughout the day. This offers a considerable opportunity for the UbiComp community to identify novel measurements and interventions that can leverage these daily variations. To illustrate this potential, we present results from an empirical study with 9 participants over 97 days investigating whether such variations manifest in low-level smartphone use, focusing on daily rhythms related to sleep. Our findings demonstrate that phone usage patterns can be used to detect and predict individual daily variations indicative of temporal preference, sleep duration, and deprivation. We also identify opportunities and challenges for measuring and enhancing well-being using these simple and effective markers of circadian rhythms.\",\n \"Title: Towards personal stress informatics: comparing minimally invasive techniques for measuring daily stress in the wild\\nYear: 2014\\n\\nAbstract: Identifying episodes of significant stress is a challenging problem with implications for personal health and interface adaptation. We present the results of a study comparing multiple modalities of minimally intrusive stress sensing in real-world environments, collected from seven participants as they carried out their everyday activities over a ten-day period. We compare the data streams produced by sensors and self-report measures, in addition to asking the participants, themselves, to reflect on the accuracy and completeness of the data that had been collected. Finally, we describe the range of participant experiences---both positive and negative---as they reported their everyday stress levels. As a result of this study, we demonstrate that voice-based stress sensing tracks with electrodermal activity and self-reported stress measures in real-world environments and we identify limitations of various sensing approaches.\",\n \"Title: Towards accurate non-intrusive recollection of stress levels using mobile sensing and contextual recall\\nYear: 2014\\n\\nAbstract: Existing user input sampling methods used for stress-related psychotherapy are plagued with problems of low recall accuracy and high intrusiveness. In this paper, we propose a contextual recall-based self-report method using mobile sensing technology that captures contextual cues including location, activity, and environmental acoustics to aid accurate recollection of stress levels. We conducted a controlled study with 36 participants. Our experimental results suggest that contextual recall outperforms recall-based self-report method by both increasing the recall accuracy and minimizing intrusiveness to participants at the same time. Moreover, we quantified the contribution of each individual contextual cue in recollecting stress levels. We found that although participants perceived all of the contextual cues to be useful, in reality, not all the contextual cues are weighted equally during the recollection process.\",\n \"Title: Collective Smile: Measuring Societal Happiness from Geolocated Images\\nYear: 2015\\n\\nAbstract: The increasing adoption of social media provides unprecedented opportunities to gain insight into human nature at vastly broader scales. Regarding the study of population-wide sentiment, prior research commonly focuses on text-based analyses and ignores a treasure trove of sentiment-laden content: images. In this paper, we make methodological and computational contributions by introducing the Smile Index as a formalized measure of societal happiness. Detecting smiles in 9 million geo-located tweets over 16 months, we validate our Smile Index against both text-based techniques and self-reported happiness. We further make observational contributions by applying our metric to explore temporal trends in sentiment, relate public mood to societal events, and predict economic indicators. Reflecting upon the innate, language-independent aspects of facial expressions, we recommend future improvements and applications to enable robust, global-level analyses. We conclude with implications for researchers studying and facilitating the expression of collective emotion through socio-technical systems.\",\n \"Title: Boosting and structure learning in dynamic Bayesian networks for audio-visual speaker detection\\nYear: 2002\\n\\nAbstract: Bayesian networks are an attractive modeling tool for human sensing, as they combine an intuitive graphical representation with efficient algorithms for inference and learning. Earlier work has demonstrated that boosted parameter learning could be used to improve the performance of Bayesian network, classifiers for complex multi-modal inference problems such as speaker detection. In speaker detection, the goal is to use video and audio cites to infer when a person is speaking to a user interface. In this paper we introduce a new boosted structure learning algorithm based on AdaBoost. Given labeled data, our algorithm modifies both the network structure and parameters so as to improve classification accuracy. We compare its performance to both standard structure learning and boosted parameter learning on a fixed structure. We present results for speaker detection and for the UCI \\\"chess\\\" dataset.\",\n \"Title: Face recognition for smart environments\\nYear: 2000\\n\\nAbstract: Smart environments, wearable computers, and ubiquitous computing in general are the coming “fourth generation” of computing and information technology. But that technology will be a stillbirth without new interfaces for interaction, minus a keyboard or mouse. To win wide consumer acceptance, these interactions must be friendly and personalized; the next generation interfaces must recognize people in their immediate environment and, at a minimum, know who they are. In this article, the authors discuss face recognition technology, how it works, problems to be overcome, current technologies, and future developments and possible applications. Twenty years ago, the problem of face recognition was considered among the most difficult in artificial intelligence and computer vision. Today, however, there are several companies that sell commercial face recognition software that is capable of high-accuracy recognition with databases of more than 1,000 people. The authors describe the face recognition technology used, explaining the algorithms for face recognition as well as novel applications, such as behavior monitoring that assesses emotions based on facial expressions\",\n \"Title: Motion field histograms for robust modeling of facial expressions\\nYear: 2000\\n\\nAbstract: This paper presents motion field histograms as a new way of extracting facial features and modeling expressions. Feature are based on local receptive field histograms, which are robust against errors in rotation, translation and scale changes during image alignment. Motion information is also incorporated into the histograms by using difference images instead of raw images. We take the principal com- ponents of these histograms of selected facial regions and use the top 20 eigenvectors for compact representation. The eigencoefficients are then used to model the temporal struc- ture of different facial expressions from real-life data in the presence of translational and rotational errors that arise from head-tracking. The results demonstrate a 44% aver- age performance increase over traditionaloptic flow method for expressions extracted from unconstrained interactions.\",\n \"Title: Capturing Spontaneous Conversation and Social Dynamics: A Privacy-Sensitive Data Collection Effort\\nYear: 2007\\n\\nAbstract: The UW Dynamic Social Network study is an effort to automatically observe and model the creation and evolution of a social network formed through spontaneous face-to-face conversations. We have collected more than 4,400 hours of data that capture the real world interactions between 24 subjects over a period of 9 months. The data was recorded in completely unconstrained and natural conditions, but was collected in a manner that protects the privacy of both study participants and non-participants. Despite the privacy constraints, the data allows for many different types of inference that are in turn useful for studying the prosodic and paralinguistic features of truly spontaneous speech across many subjects and over an extended pe- riod of time. This paper describes the new challenges and opportuni- ties presented in such a study, our data collection effort, the problems we encountered, and the resulting corpus. Index Terms—Data acquisition, privacy, speech analysis, oral communication\",\n \"Title: Beyond Context Awareness\\nYear: 2011\\n\\nAbstract: Much of the past pervasive computing research has been devoted to systems composed of a small number of devices that interact with a single individual or a small group of users. Body-worn sensors and sensors embedded in the user's environment were used to infer user location, activity, and information about the user's immediate surroundings, shaping the concept of context awareness. This issue is motivated by the fact that as technology becomes truly pervasive, we must proceed from the \\\"single user, single system\\\" perspective to \\\"large-scale heterogeneous systems\\\" involving many devices and many individuals collaborating over different spatial and temporal scales.\",\n \"Title: From Smart to Cognitive Phones\\nYear: 2012\\n\\nAbstract: As smartphones get smarter by pushing intelligence to the phone and computing cloud, they'll start to understand our life patterns, reason about our health and wellbeing, help us navigate our day, and intervene on our behalf. Here, the authors present various smartphone sensing systems that they've built, arguing that, eventually, these smartphones will evolve into cognitive phones.\",\n \"Title: Model-Based Forecasting of Significant Societal Events\\nYear: 2015\\n\\nAbstract: The article outlines some salient aspects of Embers-generated forecasts through its design considerations, system architecture, and user interface.\",\n \"Title: Social (media) jet lag: how usage of social technology can modulate and reflect circadian rhythms\\nYear: 2015\\n\\nAbstract: By nature, we are circadian creatures whose bodies' biological clocks drive numerous physiological, mental, and behavioral rhythms. Simultaneously, we are social beings. Accordingly, our internal circadian timings experience interference from externally determined factors such as work schedules and social engagements, and digital connectivity imports additional social constraints that can further misalign our individual body clocks. Misalignment between biological and social time causes social jet lag [50], which has serious physical and mental health consequences. It particularly impacts our sleep processes and neurobehavioral functioning. Examining the interplay between biological rhythms and technology-mediated social interactions, we find that technology may both modulate and reflect circadian rhythms. We also leverage such social-sensor data to infer sleep-related behaviors and disruptions and to analyze variations in attention, cognitive performance, and mood following (in)adequate sleep. We conclude with recommendations for designing technologies attuned to our innate biological traits.\",\n \"Title: Mindless computing: designing technologies to subtly influence behavior\\nYear: 2015\\n\\nAbstract: Persuasive technologies aim to influence user's behaviors. In order to be effective, many of the persuasive technologies developed so far relies on user's motivation and ability, which is highly variable and often the reason behind the failure of such technology. In this paper, we present the concept of Mindless Computing, which is a new approach to persuasive technology design. Mindless Computing leverages theories and concepts from psychology and behavioral economics into the design of technologies for behavior change. We show through a systematic review that most of the current persuasive technologies do not utilize the fast and automatic mental processes for behavioral change and there is an opportunity for persuasive technology designers to develop systems that are less reliant on user's motivation and ability. We describe two examples of mindless technologies and present pilot studies with encouraging results. Finally, we discuss design guidelines and considerations for developing this type of persuasive technology.\",\n \"Title: DoppleSleep: a contactless unobtrusive sleep sensing system using short-range Doppler radar\\nYear: 2015\\n\\nAbstract: In this paper, we present DoppleSleep -- a contactless sleep sensing system that continuously and unobtrusively tracks sleep quality using commercial off-the-shelf radar modules. DoppleSleep provides a single sensor solution to track sleep-related physical and physiological variables including coarse body movements and subtle and fine-grained chest, heart movements due to breathing and heartbeat. By integrating vital signals and body movement sensing, DoppleSleep achieves 89.6% recall with Sleep vs. Wake classification and 80.2% recall with REM vs. Non-REM classification compared to EEG-based sleep sensing. Lastly, it provides several objective sleep quality measurements including sleep onset latency, number of awakenings, and sleep efficiency. The contactless nature of DoppleSleep obviates the need to instrument the user's body with sensors. Lastly, DoppleSleep is implemented on an ARM microcontroller and a smartphone application that are benchmarked in terms of power and resource usage.\",\n \"Title: Real time heart rate and breathing detection using commercial motion sensors\\nYear: 2015\\n\\nAbstract: In this demo, we present a contactless breathing and heart rate sensing system that continuously and unobtrusively tracks physiological signals using commercial off-the-shelf radar modules. Our system provides a single sensor solution to track physical and physiological variables including coarse body movements as well as subtle and fine-grained chest movements due to breathing and heartbeat. Continuous tracking of these physiological variables especially, throughout the night can be used for sleep stage mining.\",\n \"Title: MyBehavior: automatic personalized health feedback from user behaviors and preferences using smartphones\\nYear: 2015\\n\\nAbstract: Mobile sensing systems have made significant advances in tracking human behavior. However, the development of personalized mobile health feedback systems is still in its infancy. This paper introduces MyBehavior, a smartphone application that takes a novel approach to generate deeply personalized health feedback. It combines state-of-the-art behavior tracking with algorithms that are used in recommendation systems. MyBehavior automatically learns a user's physical activity and dietary behavior and strategically suggests changes to those behaviors for a healthier lifestyle. The system uses a sequential decision making algorithm, Multi-armed Bandit, to generate suggestions that maximize calorie loss and are easy for the user to adopt. In addition, the system takes into account user's preferences to encourage adoption using the pareto-frontier algorithm. In a 14-week study, results show statistically significant increases in physical activity and decreases in food calorie when using MyBehavior compared to a control condition.\",\n \"Title: An intelligent crowd-worker selection approach for reliable content labeling of food images\\nYear: 2015\\n\\nAbstract: Food journaling is an effective way to regulate excessive food intake. However manual food journaling is burdensome, and crowd-assisted food journaling has been explored to ease user burden. The crowd-assisted journaling uses a label & verify approach where an end-user uploads his/her food image and paid crowd-workers label content of the image. Then another set of crowd-workers verify the labels for correctness. In this paper, we propose an alternative approach where we label food images with only high performing labelers. Since high performing labelers generally provide good quality labels, our approach achieves high accuracy without verifying the food labels for correctness. We also propose a machine learning algorithm to automatically identify high performing crowd-labelers from a dataset of 3925 images collected over 5 months. Such automated identification of high performing workers and elimination of needless verification reduce cost of food labeling. Specially for large scale deployments where large number of images need to be labeled, our approach can reduce overall expenses by half.\",\n \"Title: Using smartphones to sense, assess, and improve well-being\\nYear: 2014\\n\\nAbstract: The people-aware computing group at Cornell has been developing techniques to cheaply, accurately, and continuously collect data on daily human behavior, social interactions, and context. This data is subsequently leveraged to provide targeted, personalized and effective feedback to promote better mental and physical health in individuals. In this talk I will give an overview of our work on turning sensor-enabled mobile phones into well-being monitors and instruments for administering real-time/real-place interventions.\",\n \"Title: In Situ Design for Mental Illness: Considering the Pathology of Bipolar Disorder in mHealth Design\\nYear: 2015\\n\\nAbstract: In this paper, we argue that atypical cognitive, perceptual and behavioral characteristics associated with serious mental illnesses should be taken into consideration when designing health technologies. While applications have been developed to assist in the treatment of these illnesses, the specific psychological characteristics of these disorders have rarely been considered extensively in the design process. Here, we explore how an understanding of the low-level characteristics of bipolar disorder, combined with a clinically-validated treatment and patients' lived experience, can inform mHealth design. We present a novel method -- in situ design -- to support ecologically valid design, and demonstrate its use through the co-development with 9 individuals with bipolar disorder of MoodRhythm, a mobile application designed to track and stabilize daily routines. We provide evidence that mHealth design elements tailored to the characteristics and needs of individuals with bipolar disorder can result in engaging interactions.\",\n \"Title: Automatic detection of social rhythms in bipolar disorder.\\nYear: 2016\\n\\nAbstract: Objective To evaluate the feasibility of automatically assessing the Social Rhythm Metric (SRM), a clinically-validated marker of stability and rhythmicity for individuals with bipolar disorder (BD), using passively-sensed data from smartphones. Methods Seven patients with BD used smartphones for 4 weeks passively collecting sensor data including accelerometer, microphone, location, and communication information to infer behavioral and contextual patterns. Participants also completed SRM entries using a smartphone app. Results We found that automated sensing can be used to infer the SRM score. Using location, distance traveled, conversation frequency, and non-stationary duration as inputs, our generalized model achieves root-mean-square-error of 1.40, a reasonable performance given the range of SRM score (0-7). Personalized models further improve performance with mean root-mean-square-error of 0.92 across users. Classifiers using sensor streams can predict stable (SRM score >= 3.5) and unstable (SRM score <3.5) states with high accuracy (precision: 0.85 and recall: 0.86). Conclusions Automatic smartphone sensing is a feasible approach for inferring rhythmicity, a key marker of wellbeing for individuals with BD.\",\n \"Title: EmotionCheck: leveraging bodily signals and false feedback to regulate our emotions.\\nYear: 2016\\n\\nAbstract: In this paper we demonstrate that it is possible to help individuals regulate their emotions with mobile interventions that leverage the way we naturally react to our bodily signals. Previous studies demonstrate that the awareness of our bodily signals, such as our heart rate, directly influences the way we feel. By leveraging these findings we designed a wearable device to regulate user's anxiety by providing a false feedback of a slow heart rate. The results of an experiment with 67 participants show that the device kept the anxiety of the individuals in low levels when compared to the control group and the other conditions. We discuss the implications of our findings and present some promising directions for designing and developing this type of intervention for emotion regulation.\",\n \"Title: Cognitive rhythms: unobtrusive and continuous sensing of alertness using a mobile phone.\\nYear: 2016\\n\\nAbstract: Throughout the day, our alertness levels change and our cognitive performance fluctuates. The creation of technology that can adapt to such variations requires reliable measurement with ecological validity. Our study is the first to collect alertness data in the wild using the clinically validated Psychomotor Vigilance Test. With 20 participants over 40 days, we find that alertness can oscillate approximately 30% depending on time and body clock type and that Daylight Savings Time, hours slept, and stimulant intake can influence alertness as well. Based on these findings, we develop novel methods for unobtrusively and continuously assessing alertness. In estimating response time, our model achieves a root-mean-square error of 80.64 milliseconds, which is significantly lower than the 500ms threshold used as a standard indicator of impaired cognitive ability. Finally, we discuss how such real-time detection of alertness is a key first step towards developing systems that are sensitive to our biological variations.\",\n \"Title: CrossCheck: toward passive sensing and detection of mental health changes in people with schizophrenia.\\nYear: 2016\\n\\nAbstract: Early detection of mental health changes in individuals with serious mental illness is critical for effective intervention. CrossCheck is the first step towards the passive monitoring of mental health indicators in patients with schizophrenia and paves the way towards relapse prediction and early intervention. In this paper, we present initial results from an ongoing randomized control trial, where passive smartphone sensor data is collected from 21 outpatients with schizophrenia recently discharged from hospital over a period ranging from 2-8.5 months. Our results indicate that there are statistically significant associations between automatically tracked behavioral features related to sleep, mobility, conversations, smart-phone usage and self-reported indicators of mental health in schizophrenia. Using these features we build inference models capable of accurately predicting aggregated scores of mental health indicators in schizophrenia with a mean error of 7.6% of the score range. Finally, we discuss results on the level of personalization that is needed to account for the known variations within people. We show that by leveraging knowledge from a population with schizophrenia, it is possible to train accurate personalized models that require fewer individual-specific data to quickly adapt to new users.\",\n \"Title: Assessing mental health issues on college campuses: preliminary findings from a pilot study.\\nYear: 2016\\n\\nAbstract: A significant fraction of college students suffer from serious mental health issues including depression, anxiety, self-harm and suicidal thought. The prevalence and severity of these issues among college students also appear to increase over time. However, most of these issues often remain undiagnosed, and as a result, untreated. One of the main reasons of this gap between illness and treatment results from the lack of reliable data over time. While health care services in college campuses have been focusing on detection of illness onset and appropriate interventions, their tools are mostly manual surveys which often fail to capture the granular details of contexts and behaviors which might provide important cues about illness onset. To overcome the limitations of these manual tools, we deployed a smartphone based tool or unobtrusive and continuous data collection from 22 students during an academic semester. In this paper, we present the preliminary findings from our study about assessing mental health on college campuses using passively sensed smartphone data.\",\n \"Title: Nutrilyzer: A Mobile System for Characterizing Liquid Food with Photoacoustic Effect.\\nYear: 2016\\n\\nAbstract: In this paper, we propose Nutrilyzer, a novel mobile sensing system for characterizing the nutrients and detecting adulterants in liquid food with the photoacoustic effect. By listening to the sound of the intensity modulated light or electromagnetic wave with different wavelengths, our mobile photoacoustic sensing system captures unique spectra produced by the transmitted and scattered light while passing through various liquid food. As different liquid foods with different chemical compositions yield uniquely different spectral signatures, Nutrilyzer's signal processing and machine learning algorithm learn to map the photoacoustic signature to various liquid food characteristics including nutrients and adulterants. We evaluated Nutrilyzer for milk nutrient prediction (i.e., milk protein) and milk adulterant detection. We have also explored Nutrilyzer for alcohol concentration prediction. The Nutrilyzer mobile system consists of an array of 16 LEDs in ultraviolet, visible and near-infrared region, two piezoelectric sensors and an ARM microcontroller unit, which are designed and fabricated in a printed circuit board and a 3D printed photoacoustic housing.\",\n \"Title: Mobile manifestations of alertness: connecting biological rhythms with patterns of smartphone app use.\\nYear: 2016\\n\\nAbstract: Our body clock causes considerable variations in our behavioral, mental, and physical processes, including alertness, throughout the day. While much research has studied technology usage patterns, the potential impact of underlying biological processes on these patterns is under-explored. Using data from 20 participants over 40 days, this paper presents the first study to connect patterns of mobile application usage with these contributing biological factors. Among other results, we find that usage patterns vary for individuals with different body clock types, that usage correlates with rhythms of alertness, that app use features such as duration and switching can distinguish periods of low and high alertness, and that app use reflects sleep interruptions as well as sleep duration. We conclude by discussing how our findings inform the design of biologically-friendly technology that can better support personal rhythms of performance.\",\n \"Title: Detecting And Capitalizing On Physiological Dimensions Of Psychiatric Illness\\nYear: 2016\\n\\nAbstract: Serious mental illnesses, including bipolar disorders (BD), account for a large share of the worldwide healthcare burden-estimated at $62.7B in the U.S. alone. Bipolar disorders represent a family of common, lifelong illnesses associated with poor functional and clinical outcomes, high suicide rates, and huge societal costs. Interpersonal and Social Rhythm Therapy (IPSRT), a validated treatment for BD, helps patients lead lives characterized by greater stability of daily rhythms, using a 5 item paper-and-pencil self-monitoring instrument called the Social Rhythm Metric (SRM). IPSRT has been shown to improve patient outcomes, yet many patients struggle to monitor their daily routine or even access the treatment. In this paper we describe how biological characteristics of bipolar disorder can be taken into consideration when developing systems to detect and stabilize mood episodes. We describe the co-design of MoodRhythm, a smartphone and web app, with patients and therapists. It is designed to support patients in tracking their health passively and actively over a long period of time. MoodRhythm uses the phone's onboard sensors to automatically track sleep and social activity patterns. We report results of a small clinical pilot with experienced IPSRT clinicians and patients with bipolar disorder and finish by describing the role physiological computing could have not just in monitoring psychiatric illnesses according to existing broad categories of diagnosis but in helping radically tailor diagnoses to each individual patient and develop interventions that take advantage of idiosyncratic characteristics of each person's illness in order to increase patient engagement in and adherence to treatment.\",\n \"Title: EmotionCheck: A Wearable Device to Regulate Anxiety through False Heart Rate Feedback\\nYear: 2017\\n\\nAbstract: Previous studies indicate that the way we perceive our bodily signals, such as our heart rate, can influence how we feel. Inspired by these studies, we built EmotionCheck, which is a wearable device that can change users' perception of their heart rate through subtle vibrations on the wrist. The results of an experiment with 67 participants show that the EmotionCheck device can help users regulate their anxiety through false feedback of a slow heart rate.\",\n \"Title: Sensing Technologies for Monitoring Serious Mental Illnesses.\\nYear: 2018\\n\\nAbstract: Mental health is an urgent global issue. Around 450 million people suffer from serious mental illnesses worldwide, which results in devastating personal outcomes and huge societal burden. Effective symptom monitoring and personalized interventions can significantly improve mental health care across different populations. However, traditional clinical methods often fall short when it comes to real-...\",\n \"Title: 3rd International Workshop on Mental Health and Well-being: Sensing and Intervention.\\nYear: 2018\\n\\nAbstract: Mental health issues affect a significant portion of the world's population and can result in debilitating and life-threatening outcomes. To address this increasingly pressing healthcare challenge, there is a need to research novel approaches for early detection and prevention. Toward this, ubiquitous systems can play a central role in revealing and tracking clinically relevant behaviors, contexts, and symptoms. Further, such systems can passively detect relapse onset and enable the opportune delivery of effective intervention strategies. However, despite their clear potential, the uptake of ubiquitous technologies into clinical mental healthcare is rare, and a number of challenges still face the overall efficacy of such technology-based solutions. The goal of this workshop is to bring together researchers interested in identifying, articulating, and addressing such issues and opportunities. Following the success of this workshop in the last two years, we aim to continue facilitating the UbiComp community in developing a holistic approach for sensing and intervention in the context of mental health.\",\n \"Title: A practical approach to recognizing physical activities\\nYear: 2006\\n\\nAbstract: We are developing a personal activity recognition system that is practical, reliable, and can be incorporated into a variety of health-care related applications ranging from personal fitness to elder care. To make our system appealing and useful, we require it to have the following properties: (i) data only from a single body location needed, and it is not required to be from the same point for every user; (ii) should work out of the box across individuals, with personalization only enhancing its recognition abilities; and (iii) should be effective even with a cost-sensitive subset of the sensors and data features. In this paper, we present an approach to building a system that exhibits these properties and provide evidence based on data for 8 different activities collected from 12 different subjects. Our results indicate that the system has an accuracy rate of approximately 90% while meeting our requirements. We are now developing a fully embedded version of our system based on a cell-phone platform augmented with a Bluetooth-connected sensor board.\",\n \"Title: Semi-Automated Tracking: A Balanced Approach for Self-Monitoring Applications\\nYear: 2017\\n\\nAbstract: The authors present an approach for designing self-monitoring technology called \\\"semi-automated tracking,\\\" which combines both manual and automated data collection methods. Through this approach, they aim to lower the capture burdens, collect data that is typically hard to track automatically, and promote awareness to help people achieve their self-monitoring goals. They first specify three design considerations for semi-automated tracking: data capture feasibility, the purpose of self-monitoring, and the motivation level. They then provide examples of semi-automated tracking applications in the domains of sleep, mood, and food tracking to demonstrate strategies they developed to find the right balance between manual tracking and automated tracking, combining each of their benefits while minimizing their associated limitations.\",\n \"Title: Regulating Feelings During Interpersonal Conflicts by Changing Voice Self-perception\\nYear: 2018\\n\\nAbstract: ABSTRACTEmotions play a major role in how interpersonal conflicts unfold. Although several strategies and technological approaches have been proposed for emotion regulation, they often require conscious attention and effort. This often limits their efficacy in practice. In this paper, we propose a different approach inspired by self-perception theory: noticing that people are often reacting to the perception of their own behavior, we artificially change their perceptions to influence their emotions. We conducted two studies to evaluate the potential of this approach by automatically and subtly altering how people perceive their own voice. In one study, participants that received voice feedback with a calmer tone during relationship conflicts felt less anxious. In the other study, participants who listened to their own voices with a lower pitch during contentious debates felt more powerful. We discuss the implications of our findings and the opportunities for designing automatic and less perceptible emotion regulation systems.\",\n \"Title: Personalized stress monitoring: a smartphone-enabled system for quantification of salivary cortisol.\\nYear: 2018\\n\\nAbstract: Collection of salivary cortisol has been widely used as a method of investigating an array of health parameters. Monitoring of cortisol levels can help us to understand stress levels and the body’s response to stressors. Traditional methods of measuring cortisol in saliva, however, require costly equipment, trained personnel, and transportation of samples to a centralized laboratory. This creates a barrier to personal monitoring of cortisol. It also adds a level of cost and difficulty to large-scale studies which require participants to store and ship their saliva samples. Here, we present a novel system in which an individual with minimal training may collect their own saliva sample and measure it at home. Our system utilizes a lateral flow assay, a portable imaging device, and a smartphone to give salivary cortisol results in less than 15 min. We also demonstrate the use of our system on samples from a human study and give results from that study, which analyzes the relationship between cortisol levels and alertness across multiple days.\",\n \"Title: Leveraging Multi-Modal Sensing for Mobile Health: A Case Review in Chronic Pain.\\nYear: 2016\\n\\nAbstract: Active and passive mobile sensing has garnered much attention in recent years. In this paper, we focus on chronic pain measurement and management as a case application to exemplify the state of the art. We present a consolidated discussion on the leveraging of various sensing modalities along with modular server-side and on-device architectures required for this task. Modalities included are: acti...\",\n \"Title: BoostMeUp: Improving Cognitive Performance in the Moment by Unobtrusively Regulating Emotions with a Smartwatch\\nYear: 2019\\n\\nAbstract: A person's emotional state can strongly influence their ability to achieve optimal task performance. Aiming to help individuals manage their feelings, different emotion regulation technologies have been proposed. However, despite the well-known influence that emotions have on task performance, no study to date has shown if an emotion regulation technology can also enhance user's cognitive performance in the moment. In this paper, we present BoostMeUp, a smartwatch intervention designed to improve user's cognitive performance by regulating their emotions unobtrusively. Based on studies that show that people tend to associate external signals that resemble heart rates as their own, the intervention provides personalized haptic feedback simulating a different heart rate. Users can focus on their tasks and the intervention acts upon them in parallel, without requiring any additional action. The intervention was evaluated in an experiment with 72 participants, in which they had to do math tests under high pressure. Participants who were exposed to slow haptic feedback during the tests decreased their anxiety, increased their heart rate variability and performed better in the math tests, while fast haptic feedback led to the opposite effects. These results indicate that the BoostMeUp intervention can lead to positive cognitive, physiological and behavioral changes.\",\n \"Title: Identifying Mobile Sensing Indicators of Stress-Resilience\\nYear: 2021\\n\\nAbstract: AbstractResident physicians (residents) experiencing prolonged workplace stress are at risk of developing mental health symptoms. Creating novel, unobtrusive measures of resilience would provide an accessible approach to evaluate symptom susceptibility without the perceived stigma of formal mental health assessments. In this work, we created a system to find indicators of resilience using passive wearable sensors and smartphone-delivered ecological momentary assessment (EMA). This system identified indicators of resilience during a medical internship, the high stress first-year of a residency program. We then created density estimation approaches to predict these indicators before mental health changes occurred, and validated whether the predicted indicators were also associated with resilience. Our system identified resilience indicators associated with physical activity (step count), sleeping behavior, reduced heart rate, increased mood, and reduced mood variability. Density estimation models were able to replicate a subset of the associations between sleeping behavior, heart rate, and resilience. To the best of our knowledge, this work provides the first methodology to identify and predict indicators of resilience using passive sensing and EMA. Researchers studying resident mental health can apply this approach to design resilience-building interventions and prevent mental health symptom development.\",\n \"Title: 6th International Workshop on Mental Health and Well-being: Sensing and Intervention\\nYear: 2021\\n\\nAbstract: ABSTRACTMental health issues affect a significant portion of the world’s population and can result in debilitating and life-threatening outcomes. To address this increasingly pressing healthcare challenge, there is a need to research novel approaches for early detection and prevention. Toward this, ubiquitous systems can play a central role in revealing and tracking clinically relevant behaviors, contexts, and symptoms. Further, such systems can passively detect relapse onset and enable the opportune delivery of effective intervention strategies. However, despite their clear potential, the uptake of ubiquitous technologies into clinical mental healthcare is slow, and a number of challenges still face the overall efficacy of such technology-based solutions. The goal of this workshop is to bring together researchers interested in identifying, articulating, and addressing such issues and opportunities. Following the success of this workshop for the last five years, we aim to continue facilitating the UbiComp community in developing a holistic approach for sensing and intervention in the context of mental health.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":78,"string":"78"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":288,"string":"288"}}},{"rowIdx":289,"cells":{"question_id":{"kind":"string","value":"Claude Oestges"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Dynamic Wideband Directional Channel Model for Vehicle-to-Vehicle Communications\" using the following items: 1. Vehicle-to-vehicle\n2. Communications\n3. Time variance\n4. Propagation channels\n5. Statistically modeling"},"answer":{"kind":"string","value":"Vehicle-to-vehicle (V2V) communications have received a lot of attention due to their numerous applications in traffic safety. The design, testing, and improvement of the V2V system hinge critically on the understanding of the propagation channels. An important feature of the V2V channel is the time variance. To statistically model the time-variant V2V channels, a dynamic wideband directional chan..."},"correct_answer":{"kind":"string","value":"Vehicle-to-vehicle (V2V) communications have received a lot of attention due to their numerous applications in traffic safety. The design, testing, and improvement of the V2V system hinge critically on the understanding of the propagation channels. An important feature of the V2V channel is the time variance. To statistically model the time-variant V2V channels, a dynamic wideband directional chan..."},"documents":{"kind":"list like","value":["Title: First- and Second-Order Statistics of On-Body Propagation Channels\nYear: 2013\n\nAbstract: On-body channel dynamics are primarily affected by body motions, which not only cause dynamic scattering conditions but also modify the geometry of links over time. We experimentally investigate the Doppler spectra of narrowband on-body channels at 2.45 GHz in both anechoic and indoor environments. The body dynamics resulting from the motion are shown to directly affect the Doppler spectrum. An empirical model is proposed to describe the global and/or local Doppler spreads. The fit of a 3-cylinder-based physical model accounting for the arm swinging is also evaluated.","Title: Tri-polarized MIMO systems in real-world channels: Channel investigation and performance analysis.\nYear: 2012\n\nAbstract: Polarized multi-antenna systems are an effective solution for reducing inter-antenna spacing while still maintaining low inter-antenna correlation. Traditionally, only dual-polarized antenna systems are used for polarized transceivers. In this paper, tri-polarized antenna systems are investigated. Starting from the polarization mechanisms in the wireless propagation channel, it is shown that dual-polarized MIMO systems show high sensitivity to the transmitter and receiver orientation, which may be very critical in practical applications. Tri-polarized MIMO systems are introduced as a solution to obtain a robust MIMO performances, which are independent of the transmitter and receiver orientation. The performances of dual- and tri-polarized MIMO systems are evaluated on real-world measured channels, and the limits of each of these systems is highlighted.","Title: Channel Correlations And Capacity Metrics In Mimo Dual-Polarized Rayleigh And Ricean Channels\nYear: 2004\n\nAbstract: This communication highlights the impact of channel correlations, including cross-correlation terms, on various relevant metrics, namely the squared channel Frobenius norm and as well as capacity metrics, directly linked with the channel covariance matrix. Using the developed metrics, we compare various antenna configurations, with a focus on multi-polarized systems. Several orthogonal schemes, such as horizontal-vertical and slant schemes, are investigated, and analytical expressions are presented.","Title: Fast Fading Characterization for Indoor to Indoor and Outdoor to Indoor Channels.\nYear: 2011\n\nAbstract: This work models the fast fading characteristics in indoor to indoor and outdoor to indoor channels at 3.8 GHz. Starting from real world measurements, the fast fading characteristics are extracted and properly modeled, taking into account the nodes movement conditions. For static environments, the fast fading is modeled with the well known Ricean distribution. As expected the K-factor depends on the path loss. On the other hand, in mobile environments, the probability density function of the signal envelope is accurately described by the recently developed second-order scattering fading (SOSF) distribution. The SOSF distribution combines the Rayleigh, Ricean and double Rayleigh fading and any linear combinations of these. Our results show that the higher the mobility, the more severe is the fading.","Title: Spatial separation of multi-user MIMO channels\nYear: 2009\n\nAbstract: Since multi-antenna (MIMO) systems are becoming more popular thanks to their inherent potential for capacity improvement, interference from MIMO transceivers is an in- creasingly serious concern. Spatial multiplexing schemes are particularly vulnerable to multi-user interference. Fortunately, this interference can be mitigated, when the channel matrices show a sufficient spatial separation. In this paper, we quantify the separability of multi-user MIMO channels using actual measurements in a scenario where a single outdoor base station transmits to two indoor mobile receivers. To quantify the spatial distance between the two users, we compare the spatial correlation matrices using two simple measures: (i) matrix collinearity, and (ii) the condition number ratio. Both measures are directly linked to MIMO system performance. Our measurement-based evaluations demonstrate that the downlink channels of different users can have a significantly different spatial structure, even when the users are in the same room. This leads to the following conclusions: (i) new multi-user MIMO models are needed to describe the spatial characteristics of different users, and (ii) spatial interference can be well managed by appropriate scheduling and precoding algorithms.","Title: Accuracy of depolarization and delay spread predictions using advanced ray-based modeling in indoor scenarios\nYear: 2011\n\nAbstract: This article investigates the prediction accuracy of an advanced deterministic propagation model in terms of channel depolarization\n and frequency selectivity for indoor wireless propagation. In addition to specular reflection and diffraction, the developed\n ray tracing tool considers penetration through dielectric blocks and/or diffuse scattering mechanisms. The sensitivity and\n prediction accuracy analysis is based on two measurement campaigns carried out in a warehouse and an office building. It is\n shown that the implementation of diffuse scattering into RT significantly increases the accuracy of the cross-polar discrimination\n prediction, whereas the delay-spread prediction is only marginally improved.","Title: Analytical Multi-User MIMO Channel Modeling: Subspace Alignment Matters.\nYear: 2012\n\nAbstract: For a receiver that observes a mixture of desired and interfering multiple-input multiple-output (MIMO) transmissions, not all interference has the same severity: its effect is modulated by the degree of alignment between the eigenspaces of the desired and undesired channel matrices.An analytical channel model is proposed to account for this effect. Two metrics of eigenspace compatibility are studied, and a method to generate channels of a given degree of compatibility is derived. The resulting model is parameterized using radio channel measurement data, and an implementation recipe for immediate use of the model is provided.","Title: Modeling Time-Variant Fast Fading Statistics of Mobile Peer-to-Peer Radio Channels\nYear: 2011\n\nAbstract: The radio channels between nodes of an indoor peer-to-peer network show specific fast fading characteristics. Depending on the mobility and on the scattering properties of the environment, different kinds of fading distributions can occur: Ricean fading between static nodes, but also Rayleigh or even double-Rayleigh fading between mobile nodes. We investigate fast fading in indoor peer-to-peer networks based on radio channel measurements. It turns out that the fading statistics change over time. While the predominant fading mechanism is a combination of Rayleigh and double-Rayleigh fading, Ricean fading also occasionally occurs. On top of that, indoors, the statistics of the fast fading change over time even for small-motions of the nodes, since the propagation environment is inhomogeneous. We comprehensively model these effects using a hidden Markov model, parameterized from our measurements. The model is validated, revealing a convincing fit between the model and the measurements.","Title: Mutual Coupling Effects On The Channel Capacity And The Space-Time Processing Of Mimo Communication Systems\nYear: 2003\n\nAbstract: The channel capacity and the performance of MIMO systems in the presence of fading correlation and antenna coupling are investigated. Simulation results demonstrate that mutual coupling can improve the performance depending on the inter-element spacing and the richness of scattering. It is shown that the bit error rate performance of spatial multiplexing is particularly influenced by the decorrelation/correlation effect caused by mutual coupling. On the other hand, the bit error rate performance of transmit diversity is mainly affected by the resulting modification of antenna gain-and received power.","Title: A ray tracing algorithm using the discrete prolate spheroidal subspace\nYear: 2013\n\nAbstract: Ray tracing (RT) is an accurate propagation prediction tool that has been widely used to simulate channel characteristics in indoor environments. To date, the developed RT tool includes not only specular reflection, penetration through dielectric blocks and diffraction, but also diffuse scattering mechanisms. The accuracy, provided by a detailed modeling of the environment, comes at the cost of a high computational complexity, which directly scales with the number of propagation paths considered. We are interested in simulating the radio propagation conditions for a mobile terminal, communicating in a frame based communication system indoors with several fixed nodes. This communication shall be used to obtain the position of the mobile terminal in indoor scenario. Therefore, the correlated temporal and spatial evolution of the channel impulse response is of utmost concern. In this paper, we propose a method to significantly reduce the computational complexity of RT by using a projection of all propagation paths on a subspace spanned by two-dimensional discrete prolate spheroidal (DPS) sequences. With this method the computational complexity can be reduced by more than one order of magnitude for indoor scenarios. The accuracy of our low-complexity DPS subspace based RT algorithm is verified by numeric simulations.","Title: An Analytical Modeling of Polarized Time-Variant On-Body Propagation Channels with Dynamic Body Scattering\nYear: 2011\n\nAbstract: On-body propagation is one of the dominant propagation mechanisms in wireless body area networks (WBANs). It is characterized by near-field body-coupling and strong body-scattering effects. The temporal and spatial properties of on-body channels are jointly affected by the antenna polarization, the body posture, and the body motion. Analysis on the time variant properties of on-body channels relies on a good understanding of the dynamic body scattering, which is highly dependent on specific scenarios. In this paper, we develop an analytical model to provide a canonical description of on-body channels in both time and space domains to investigate the on-body propagation over the trunk surface of a walking human. The scattering from the arms and the trunk in different dimensions is considered with a simplified geometrical description of the body and of the body movements during the walk. A general full-wave solution of a polarized point source with multiple cylinder scattering is derived and extended by considering time evolution. The model is finally validated by deterministic and statistical comparisons to different measurements in anechoic environments.","Title: A New Double-Directional Channel Model Including Antenna Patterns, Array Orientation, and Depolarization\nYear: 2010\n\nAbstract: Multiple-input-multiple-output (MIMO) wireless channel models are often too simplistic to accurately model wireless propagation effects or too complex and/or site specific to be used for analytical purposes. In this paper, we develop a double-directional MIMO channel model that accounts for important propagation effects like scattering, clustering, and channel depolarization and antenna effects like antenna diversity, cross polarization, and random array orientation, while still retaining an intuitive representation. The proposed model can be parameterized using channel measurements obtained from site-specific measurement campaigns or from standard-based channel models. We show, using simulations, that the proposed model captures channel and antenna effects not included in other models, like the third-generation partnership program (3GPP) spatial channel model, the WINNER, and the IEEE 802.11n channel model. We use the model to study the impact of random orientation and channel depolarization on the data rates of a MIMO system.","Title: Channel Correlation And Cross-Polar Ratio In Multi-Polarized Mimo Channels: Analytical Derivation And Experimental Validation\nYear: 2008\n\nAbstract: This paper proposes a closed-form expression for the correlation coefficient and the cross-polarization discrimination (XPD) of a randomly oriented dual-or tri-polarized MIMO system. The environment is supposed to have a truncated Laplacian power azimuth spectrum that is widely used in standardization bodies. Correlation and XPD are shown to be highly sensitive to receiver orientation, azimuth spread and environment depolarization behavior. Measurements were conducted at 3.5 GHz to validate the theoretical model. Good agreement is obtained between theoretical curves and experimental results for correlation and XPD when comparing at different receiver orientations.","Title: Mutual Information And Error Probability Of Dual-Polarized Systems\nYear: 2007\n\nAbstract: In this communication, we address the potential benefits of dual-polarized arrays in 2 x 2 MIMO systems. We start with a new and simple analytical model of dual-polarized Rayleigh and Ricean fading channels, which relies on a limited number of physical parameters, such as the spatial correlations, the co-polar gain imbalance and the cross-polar discrimination. Then, we investigate the multiplexing advantage of dual-polarized transmissions through the evaluation of the ergodic mutual information. Finally, the performance of two space-time coding schemes (Alamouti O-STBC and uncoded Spatial Multiplexing) is evaluated via a detailed analysis of the pairwise error probability.","Title: Indoor Wireless Communications With Multiple Antennas And Polarizations: From Channel Characterization To Performance Simulation\nYear: 2008\n\nAbstract: In this paper, we describe experimental results characterizing the frequency/space/polarization selectivity of indoor channels at 1.9 GHz. Regarding the delay-angle dispersion, a clustered geometry-based model is developed from measurement results and validated. Regarding dual-polarized channels, a simple analytical model is extracted from experimental data, accounting for the cross-correlation between the various parameters. Finally, narrowband dual-polarized and single-polarized transmissions are compared in real-world indoor channels based on performance metrics for multiplexing and diversity gains.","Title: Empirical Investigation Of Multi-Link Separation For Indoor Mimo Channels\nYear: 2011\n\nAbstract: Based on multi-node multi-antenna channel measurements in a multi-wall office environment, we estimate the degree of separation between multiple MIMO links by means of two metrics: the correlation matrix distance and the shadowing correlation. Both nomadic and mobile node scenarios are considered and compared. Empirical models are eventually derived. Our analysis reveals that the average separation between two MIMO links sharing a joint transmitter is usually lower in mobile scenarios than in nomadic scenarios, and is strongly related to the spatial correlation of the individual MIMO links. However, there appears to be no relationship between the correlation matrix distance and the shadowing correlation.","Title: Modeling Outdoor Macrocellular Clusters Based on 1.9-GHz Experimental Data\nYear: 2007\n\nAbstract: This paper presents a stochastic geometry-based model of the multiple-input-multiple-output channel, as seen by the user terminal based on the extraction of cluster parameters from wideband data measured at 1.9 GHz in short-range outdoor macrocellular environments. Clusters are first identified through data visual inspection. Then, a statistical characterization is carried out based on a delay-ori...","Title: Robust Signal Constellations For Spatial Multiplexing In The Presence Of Real Fading Propagation Channels\nYear: 2003\n\nAbstract: Spatial multiplexing is employed in MIMO communication systems to increase spectral efficiency. The performance of spatial multiplexing is highly dependent on the propagation conditions such as the richness of scattering, the presence of dominant components and the inter-element spacings. In this paper, new robust signal constellations for use in spatial multiplexing over real fading propagation channels are developed. It is shown that these new constellations are by far more robust against fading correlations and high Rice factor than the classical PSK and QAM constellations. With these new constellations, spatial multiplexing presents excellent symbol error rate performance whatever the propagation environment and the inter-element distance.","Title: The COST 2100 MIMO channel model\nYear: 2012\n\nAbstract: The COST 2100 channel model is a geometry- based stochastic channel model (GSCM) that can reproduce the stochastic properties of MIMO channels over time, frequency, and space. In contrast to other popular GSCMs, the COST 2100 approach is generic and flexible, making it suitable to model multi-user or distributed MIMO scenarios. In this article a concise overview of the COST 2100 channel model is presented. Main concepts are described, together with useful implementation guidelines. Recent developments, including dense multipath components, polarization, and multi-link aspects, are also discussed.","Title: Tri-polarized spectrum sensing based on an experimental outdoor-to-indoor cognitive-radio scenario.\nYear: 2012\n\nAbstract: Compared to classical spatially separated multiple antenna system, cross-polarized co-located antenna systems are an interesting way to reduce equipment size while reducing the inter-antenna correlation. In this paper the spectrum sensing of a Cognitive Radio (CR) system taking advantage of polarization diversity under Rayleigh fading is investigated and compared to an equivalent system using spatial diversity. This analysis is based on a theoretical formulation applied to a real-world scenario. For this purpose, an outdoor-to-indoor measurement campaign at a frequency of 3.5 GHz is realized, where an indoor secondary user senses the signals received from an outdoor primary base station. The signals received at each antenna are first combined and then applied to an energy detector. The theoretical expressions are simulated in the measurement context. The detection probability behavior as a function of distance between the Primary Transmitter (PTx) and the Secondary Terminal (STE) and the inter-antenna correlation effect on the sensing performance are studied.","Title: A Study On Polarimetric Properties Of Scattering From Building Walls\nYear: 2010\n\nAbstract: The polarimetric characteristics of the signal back scattered from a building wall are studied in this paper with the aid of MIMO measurements and Ray Tracing simulation. A very simple environment with a single rural building amid an open area is considered to reduce complexity and better isolate the different kinds of back-scattered contributions: specular reflection, diffractions, diffuse scattering. Narrowband and wideband metrics are utilized to evaluate scattering characteristics focusing in particular on its polarization properties.","Title: Performance Evaluation of Interference Bound Backhaul Links in High Capacity Wireless Networks\nYear: 2014\n\nAbstract: An innovative architecture employing wireless backhaul in hierarchical wireless networks is considered in this paper to provide high throughput densities. Multi-beam antennas, combined with aggressive frequency reuse have recently been exploited to increase the throughput density in densely deployed wireless networks. However, large number of narrow beams cause not only co-channel interference but also inter-cell interference. To mitigate this problem, amplitude tapering in multi-beam antennas is investigated in this paper. Results show that tapered beams significantly improve the carrier to interference ratio from 5 to 8 dB and consequently achieve downlink throughput density over 0.65 Gbps/km$$^2$$2. An overall throughput density of 1.2 Gbps/km$$^2$$2 is expected when taking both up- and downlinks into account.","Title: A Spatially-Correlated Tapped Delay Line Model For Body Area Networks\nYear: 2008\n\nAbstract: Using wireless sensors worn on the body for pervasive monitoring is expected to become more and more common in the next years. The achievement of this application requires solving some challenges, especially in the power saving domain. In order to develop efficient power radio communications, an interesting investigation field is the multi-sensor MIMO (MS-MIMO) ultra-wideband (UWB) network. It is realistic to assume that each sensor carries one antenna, while the central device uses an antenna array. In this paper, a new analytical channel model for the diffracted waves mechanism is proposed. It is derived from the existing IEEE 802.15.4a standard channel model and innovates with space-time considerations.","Title: Design issues for MIMO systems in various fading situations\nYear: 2006\n\nAbstract: This contribution provides a fresh look at the asymptotic (in terms of number of antennas) design of multiple-antenna wireless systems, with the goal of giving useful insights on the deployment of future MIMO systems. For the i.i.d. Gaussian and double-directional models, we provide guidelines in terms of the repartition of the antennas between the transmitter and the receiver, and study the influence of array geometry on the ergodic mutual information per antenna. Furthermore, we compare the LOS and NLOS situations, and evaluate the relative importance of the LOS component and path loss in Ricean fading, as well as in the low-rank Ricean component case.","Title: Space-Time Code Design for Correlated Ricean MIMO Channels at Finite SNR\nYear: 2008\n\nAbstract: Space-time code (STC) designs commonly rely on the assumptions of independent and identically distributed (i.i.d.) Rayleigh channels (being either slow or fast fading) and high signal-to-noise ratio (SNR). However, it has been shown that poor scattering conditions can have detrimental effects on the performance of STCs and that the behavior of codes at high SNR is radically different from the fini...","Title: A Time-Variant Statistical Channel Model For Tri-Polarized Antenna Systems\nYear: 2010\n\nAbstract: Polarized MIMO systems are an efficient solution for reducing inter-antenna correlation while maintaining compact terminal size. In this paper, a time-variant statistical channel model is proposed for tri-polarized antenna systems. The model is based on a coherent and a scattered component, where each component includes inter-channel correlation and cross-polar discriminations. The temporal variations of the channel are separated in slow and fast channel variations. A measurement campaign has been performed at 3.6 GHz to parameterize the model, in both static and mobile cases. A variant of the variogram technique has been adopted for extracting the slow-varying channel parameters. Experimental results are investigated and presented. The Doppler spectrum of the fast channel variations show fundamental differences between the static case and the mobile case. Finally, it is explained how the proposed model can be generated.","Title: Low-complexity sub-band divided ray tracing for UWB indoor channels\nYear: 2014\n\nAbstract: Ray tracing has been extensively used to simulate indoor channel characteristics. For an ultra-wideband system, the channel characteristics vary significantly over the entire bandwidth. To cope with this, sub-band divided RT has been proposed by dividing the frequency of interest into multiple subbands and superposing the RT results at the individual center frequency of each subband. Thus, the computational complexity is directly proportional to the number of subbands. In this paper, we propose a mathematical method to significantly reduce the computational complexity of the sub-band divided RT, making it almost independent of the number of subbands. It is important to note that, based on our approach, not only the determination of the rays reaching a give location is made only once, but also the electromagnetic calculation of the received signal is not needed to perform repeatedly. The accuracy of low-complexity subband divided RT algorithm is verified through a measurement campaign.","Title: Calibration of indoor UWB sub-band divided ray tracing using multiobjective simulated annealing\nYear: 2014\n\nAbstract: Sub-band divided ray tracing (RT) has been widely used to reproduce as reliably as possible the ultra-wideband (UWB) radio wave propagation channel in realistic indoor environments. However, its accuracy is strictly limited by the available description of the environment. Moreover, its computational complexity scales with the number of selected subbands and the number of propagation paths. In the present work, our RT tool considers not only deterministic propagation paths but also diffuse scattering components. Based on a low-complexity sub-band divided RT implementation, we propose a calibration method for indoor UWB sub-band divided RT. The method estimates the optimal material parameters, including the dielectric parameters and the scattering parameters, using channel measurements and multiobjective simulated annealing (MOSA). This calibration can improve the accuracy of sub-band divided RT in terms of the power delay profile (PDP) and the root mean square (RMS) delay spread for all test locations including those not considered by the calibration. A measurement campaign is used to verify the calibration technique.","Title: On the use of ray tracing for performance prediction of UWB indoor localization systems\nYear: 2013\n\nAbstract: The most important factors impairing the performance of radio-based indoor localization systems are propagation effects like strong reflections or diffuse scattering. To the full extent, these effects can be captured only by time-consuming measurement campaigns. Ray tracing (RT) offers the possibility to predict the radio channel for a certain environment, avoiding the need for measurements. However, it is crucial to include all relevant propagation mechanisms in the RT as well as to validate the obtained results. In this paper, we analyze if sub-band divided RT can yield realistic ultra-wideband channel impulse responses. We use the RT results for performance analysis of multipath-assisted localization, which depends directly upon the above mentioned propagation effects. In particular, it has been shown that the ratio of the signal energies of deterministically reflected paths to interfering diffuse components quantifies the amount of position-related information of deterministic multipath components. Comparison of this ratio to measurement data is thus useful to validate the sub-band divided RT. The results highlight the need for proper modeling of the diffuse multipath, as estimates of this energy ratio using RT are often overly optimistic. However, the obtained localization performance predictions using measurements and RT show general agreement.","Title: Shadow Fading Correlation in High-Speed Railway Environments\nYear: 2015\n\nAbstract: In the design of diversity and fast handover schemes for high-speed railways (HSRs), a better understanding of the shadow fading correlation properties is required. In this paper, both auto- and cross-correlation models of shadow fading in HSR environments are proposed based on a large set of measurements with 6146 cells in China. The measurements are conducted using a practically deployed and operative GSM-Railway (GSM-R) system at 930 MHz, to reflect the real conditions of shadow fading in the HSR environments. 7 typical HSR environments and the realistic base station (BS) parameters are considered in the analysis. It is found that the decorrelation distance is correlated with the standard deviation of shadow fading, and is generally larger than 100 m in most of HSR environments. The cross-correlation of shadow fading between two neighboring BSs dependents on the BS height and the tilt angle of the antenna, and a heuristic truncated Gaussian distribution model of cross-correlation is proposed. The model is validated by the measurements conducted in another operative HSR line. The results can be used to exploit the simulation algorithms, to analyze the signal-to-interference-ratio (SIR) properties, and to develop new and better handover schemes for HSRs.","Title: A stochastic geometrical vector model of macro- and megacellular communication channels\nYear: 2002\n\nAbstract: This paper describes a physically based stochastic approach that allows to predict the narrowband fading statistics for macro- and megacellular networks operating in urban areas. On one hand, macrocellular channels have been mainly covered in the literature by means of empirical models. On the other hand, megacells are typical of upcoming communication systems, such as broadband wireless access and high-altitude platform-based net- works. Generally, the path gain of a wireless fading channel can be statistically characterized by a Ricean distribution, which includes Rayleigh fading as a particular case. The key parameter of the dis- tribution is the -factor , defined as the ratio of the dominant component to the scatter contribution. In this paper, the -factor is estimated by means of a physical model, conditionally to a set of geometrical parameters, such as the building height, the street width and the base station-to-terminal distance. These parameters are statistically described by analytical distributions. The model is successfully compared with experimental data at 1.6 GHz and typical applications are presented. Finally, because of its physical background, the model performs very well in analyzing polariza- tion (MIMO) multiplexing schemes.","Title: Wide-band SIMO 1×2 measurements and characterization of outdoor wireless channels at 1.9 GHz\nYear: 2004\n\nAbstract: This paper aims at characterizing the spatial wireless channel at 1.9 GHz, based on a 1×2 measurement chain. A typical campus/residential area and an industrial area have been investigated. The measurement equipment is constituted by an 80-MHz transmitter at 1.9 GHz, located at the top of a building. At the receiver, two omnidirectional antennas are connected to a wide-band channel sounder through a switch in order to measure an estimate of the instantaneous vector channel. It is found that the Ricean K-factor and the delay spread are lognormally distributed, while the azimuth spread at the receive side follows a Gaussian distribution. The range dependence of various parameters are pointed out and compared with empirical models. The impacts of antenna spacing and array orientation on the channel correlation are highlighted and compared to theoretical simulation results. Finally, the cross-correlation properties between K-factor, delay spread, azimuth spread, and channel correlation are analyzed.","Title: Mutual information of non-Kronecker structured dual-polarized 2×2 channels\nYear: 2006\n\nAbstract: This paper investigates the mutual information of several 2×2 systems using orthogonal polarizations. Analytical approximations of the mutual information in equi-power allocation scenarios are derived and compared in both Rayleigh and Ricean fading conditions.","Title: Validity of the Kronecker Model for MIMO Correlated Channels\nYear: 2006\n\nAbstract: The goal of this paper is to investigate the validity of the Kronecker model for MIMO correlated channels. First, mathematical and equivalent propagation conditions of validity are detailed. In a second part, we address several areas where the Kronecker model is not valid. We also review the one-ring model and experimental results dealing with the validation of the Kronecker model. Based on these scarce results, the preliminary conclusion is that the Kronecker model might not be valid for arrays larger than 2times2 when antenna correlations are high across both receive and transmit arrays. The paradox is that the Kronecker model has been developed and is being widely used to account for correlation. This is in strong contrast with the popular belief that the Kronecker model is valid in many indoor and outdoor cases","Title: Impact of Antenna Coupling on 2 × 2 MIMO Communications\nYear: 2007\n\nAbstract: The impact of mutual coupling induced by two closely spaced minimum scattering antennas at the subscriber unit on 2 times 2 multiple-input multiple-output channels and communications is investigated. Both (de)correlation effects and variations of antenna gain resulting from coupling mechanisms are considered. Relationships between coupling and correlations/channel Frobenius norm are discussed, pointing out the role of the interelement spacing, the array orientation, and the richness of scattering. The analysis also yields useful insight into the influence of mutual coupling on capacity and system performance","Title: Multi-Polarized MIMO Communications: Channel Model, Mutual Information and Array Optimization\nYear: 2007\n\nAbstract: This paper considers the use of nr times nt dual-polarized arrays for improving the mutual information of MIMO communications. We first develop an elegant model of the multi-polarized MIMO channel, which allows to account for spatial correlation and depolarization effects. The major advantage of the model lies in its analytical expression, whose parameters have a clear physical meaning. In a second part, we investigate the ergodic mutual information of multi-polarized schemes, and derive a condition upon which multi-polarized transmissions offer a higher capacity than equivalent uni-polarized schemes using the same number of antennas under the same overall array dimensions.","Title: Wideband MIMO Car-to-Car Radio Channel Measurements at 5.3 GHz\nYear: 2008\n\nAbstract: Measurements of car-to-car (C2C) radio channels with 60 MHz bandwidth at 5.3 GHz have been performed in Helsinki, Finland. We focused on 30x30 multiple-input multiple- output (MIMO) measurements, conducted in four environments (urban, sub-urban, campus and highway), under quasi-realistic traffic conditions. As first results, we present in this paper the delay spread statistics for each investigated environment. The largest values of root-mean-square (RMS) delay spread, roughly 2 mus, were obtained in the urban environment. The narrowband channel fading statistics have also been derived using composite distributions, in order to assess the global fading statistics.","Title: Analytical model and experimental validation of cross polar ratio in polarized MIMO channels\nYear: 2008\n\nAbstract: Cross-polarized antenna systems are used to reduce equipment size in MIMO systems while still achieving low inter-antenna correlation. One fundamental parameter of cross-polarized MIMO systems is the cross-polar discrimination (XPD). This paper proposes a model to determine the XPD as a function of channel condition and under different antenna configurations. The environment is supposed to have a truncated Laplacian Power Angular Spectrum (PAS) that is widely used in standardization bodies. Antenna XPD is shown to be sensitive to different channel conditions, as well as to different receiver orientations. Measurements were conducted at 3.5 GHz to validate the theoretical model. Good agreement is obtained between theoretical XPD and experimental results.","Title: Radio Channel Characterization for Moderate Antenna Heights in Forest Areas\nYear: 2009\n\nAbstract: This paper describes the results achieved by an experimental campaign whose goal was to characterize the directional propagation channel at 1.9 GHz in forested areas for moderate antenna heights. These experimental results are useful in the context of pedestrian radio-localization systems relying on cellphone signals. Wideband experimental results, which are recorded with transmit-to-receive distances ranging from 40 to 110 m, indicate that the path loss is well modeled by ITU-R Recommendation 833-4. The temporal fading and multipath dispersion are also analyzed. The delay spread, which ranges from 60 to 120 ns, is strongly anticorrelated with the temporal coherence and increases with transmit-to-receive distance. The azimuth spread remains limited, with average values of about 15deg.","Title: Polarimetric Measurements for Spatial Wideband MIMO Channels\nYear: 2009\n\nAbstract: This paper investigates the polarization behaviour of indoor multi-polarized MIMO channels at 3.6 GHz. Measurements have been carried out in non-line-of-sight (NLOS) and line-of-sight (LOS) using a dual-polarized transmitter and a tri-polarized receiver. The spatial and delay characteristics are extracted using a per-tap beamforming algorithm. Distinct waves are isolated and the polarization of each wave is expressed in terms of its spherical components. The evolution of the waves polarization is investigated as function of its physical propagation parameters. The polarization of the waves is shown to be sensitive to spatial characteristics, while being insensitive to delay. Direct line-of-sight rays show to have higher XPD than in the NLOS case, while the reflected rays have a similar XPD than in a NLOS case.","Title: CRBs for UWB Multipath Channel Estimation: Impact of the Overlapping Between the MPCs on MPC Gain and TOA Estimation\nYear: 2009\n\nAbstract: In this paper we study the impact of the overlapping between neighboring MPCs (multipath component) on the performance of channel estimation. We consider IR-UWB (impulse radio) signals, and the IEEE802.15.3a and IEEE802.15.4a UWB channel models. We show that for a pulse width (PW) sufficiently smaller than the average MPC rate of arrival (ROA) the probability to have more than three overlapping MPCs is relatively small. We derive the CRBs (Cramer Rao bound) for the joint estimation of the MPC gain and TOA (time of arrival) in the case of up to three overlapping MPCs. We compute also the average CRBs. We show that the CRBs obtained by averaging more than 80% of possible cases of the channel, are very close to the bounds obtained under the non-overlapping assumption (NOLA).","Title: Polarization measurements and modeling in indoor NLOS environments\nYear: 2010\n\nAbstract: Cross-polarized antenna systems are an attractive way to reduce equipment size while maintaining low interantenna correlation. In this paper, the polarization behaviour of indoor channels is investigated. A measurement campaign has been conducted at 3.6 GHz for a dual-polarized transmitter and a tri-polarized receiver in a non-Line-of-Sight (NLOS) scenario. The spatial and delay characteristics are extracted using a pertap beamforming algorithm. Distinct paths are isolated and the polarization of each wave is expressed in terms of its spherical components. The cross-polarization discrimination (XPD) of the wave is investigated as a function of its physical propagation parameters. The XPD of the wave is shown to be sensitive to spatial characteristics, while being insensitive to delay.","Title: Wideband Measurement-Based Modeling of Inter-Vehicle Channels in the 5-GHz Band\nYear: 2013\n\nAbstract: In this paper, we describe a new wideband single-input-single-output (SISO) channel model for vehicle-to-vehicle (V2V) channels, based on an extensive measurement campaign carried out at 5.2 GHz around Helsinki, Finland, in August 2007. Both the currently well-known non-stationary behavior and the measured characteristics of the V2V channel motivate the use of a geometry-based stochastic channel modeling (GSCM) approach rather than a classical tapped delay line (TDL) approach. For the time-variant contributions stemming from discrete scatterers, the propagation distance can be deterministically estimated (i.e., geometrically), whereas the fading can be modeled as the combination of a distance-decaying process and two stochastic small- and large-scale processes. The complete parameterization of the V2V wideband channel model, the recipe for its implementation, and the analysis of its validity are also provided in this paper.","Title: Empirical Modeling of Nomadic Peer-to-Peer Networks in Office Environment\nYear: 2011\n\nAbstract: We experimentally characterize nomadic peer-to peer channels in a multi-wall indoor office environment. In particular, we derived models of path-loss, shadowing and fading statistics at 3.8 GHz in fixed scenarios, and compare them with existing results. Highlights of the paper include a multi-wall path loss model, the separation between obstruction, nomadic, and dynamic shadowing, a dynamic shadowing correlation model, as well as a multi-link analysis of MIMO links.","Title: Non-Stationary Narrowband MIMO Inter-Vehicle Channel Characterization in the 5-GHz Band\nYear: 2010\n\nAbstract: In this paper, we describe measurements and models of 30 × 30 narrowband multiple-input-multiple-output (MIMO) vehicle-to-vehicle (V2V) radio propagation channels at 5.3 GHz. Four environments were considered: a campus, a highway, a suburban area, and an urban area. Since the scattering environment may rapidly change in V2V communications, we first investigate the validity of the wide-sense stationarity (WSS) assumption for such channels using the correlation matrix distance (CMD), which is a metric for the characterization of the MIMO channel nonstationarity. Moreover, statistical channel models were developed for these environments, which take into account the non-stationary behavior of the measured V2V channels. The large-scale fading was found to be lognormally distributed, whereas the small-scale fading was characterized by the flexible Weibull distribution. Finally, the non-stationary behavior of both large-scale fading and small-scale fading statistics was investigated.","Title: Clustered channel characterization for indoor polarized MIMO systems\nYear: 2009\n\nAbstract: A cluster-based channel model is presented that includes polarization characteristics. Measurements have been carried out in an indoor environment at 3.6 GHz using a dual-polarized transmitter and a tri-polarized receiver. Individual propagation paths are extracted using the SAGE algorithm, and a cross-polar discrimination (XPD) per ray is defined. Clusters are identified in the co-elevation-azimuth-delay domain, with an automatic clustering algorithm. The cluster properties are investigated and polarization characteristics are identified on a per-cluster basis. Finally, the obtained model is simulated and extraction-independent parameters are compared with experimental parameters for validation.","Title: Capacity performance of outdoor-to-indoor relay schemes in measured radio channels\nYear: 2009\n\nAbstract: In this paper, the capacity of several outdoor-to-indoor relay schemes has been investigated using real-world measurements at 2.45 GHz. The considered scenario encompasses an outdoor base station, possibly using multiple antennas, communicating via two hops to distributed single antenna terminals located inside a building. The single-antenna relays are located along the so-called best wall. Capacity results show that in most cases, relaying techniques increase the capacity, even when constraining the global power expense of the network. Considering a combining scheme using the source-to-destination in addition to the relay link does not bring huge benefits for the measured outdoor-to-indoor channels. The best performance is obtained in a relay-and-forward scheme using multiple cooperative relays.","Title: A Polarized Clustered Channel Model for Indoor Multiantenna Systems at 3.6 GHz\nYear: 2010\n\nAbstract: Multiple-input-multiple-output (MIMO) technologies allow high data rates to be obtained, but they suffer from interantenna correlation caused by the limits in interantenna spacing. Polarized MIMO systems resolve this problem by using colocated perpendicularly polarized antennas that have low interantenna correlation. In this paper, a polarized single-directional channel model for 2×N MIMO systems at 3.6 GHz in an indoor environment is presented. The wireless channel is modeled as a sum of clusters, where each cluster has specular and diffuse components. The polarization of the specular component of the clusters is included by considering a per-path polarization. The diffuse component of the clusters is modeled with a Fisher-Bingham (FB5) spectrum in the azimuth-coelevation domain and with an exponential power delay profile. Polarization is analyzed by introducing the cross-polar discrimination of the exponential power delay profile parameters. All of the parameters in the model are extracted from an experimental measurement campaign performed in an indoor environment at 3.6 GHz. Individual paths are extracted from the measurements with the space-alternating generalized expectation-maximization (SAGE) algorithm. These paths are grouped in clusters within the azimuth of arrival-elevation of arrival-delay domains at the receiver side using automatic clustering algorithms. The specular component properties of the clusters are then determined. Finally, the diffuse components of the clusters are investigated and parameterized by applying a beamforming algorithm on the diffuse part of the impulse response.","Title: Statistical Characterization of Dynamic Multi-Path Components for Vehicle-to-Vehicle Radio Channels\nYear: 2015\n\nAbstract: To statistically model time-variant vehicle-to-vehicle (V2V) channels, the dynamic multi-path components (MPCs) are characterized based on suburban measurements conducted at 5.3 GHz. The correlation matrix distance (CMD) is used to determine the size of local wide-sense stationary (WSS) region. Within each WSS time window, MPCs are extracted using wideband spatial spectrum of Bartlett beamformer. A MPC distance (MCD)-based tracking algorithm is used to identify the \"birth\" and \"death\" of MPCs over different WSS regions, and the lifetime of MPC is modeled with a truncated Gaussian distribution. Distributions of number of MPCs and their positions are statistically modeled. The MPC characterization considers both angular and delay domain properties as well as the dynamic evolution of MPCs over different WSS regions. The results shows insight into the dynamic behaviors of MPCs in V2V environments, and is useful for the scatterer modeling in the geometry-based stochastic channel modeling.","Title: Centimeter- and Millimeter-Wave Channel Modeling Using Ray-Tracing for 5G Communications\nYear: 2015\n\nAbstract: A ray-tracing tool, including specular reflection, diffraction and attenuation by foliage, is experimentally validated at 12 and 30 GHz in a suburban environment. The tool is then applied to double directional channel modeling at 30 GHz in a real-world urban area in downtown Brussels. Azimuth-, elevation- and delay-spread are computed and analyzed on a stochastic viewpoint. It is found that elevation spreads remain limited (below 3 degrees), while azimuth-spreads are on average similar at both sides of the link (with a mean value of 12 degrees). Delay-spreads vary significantly over the user's locations, with a mean value of 45 nanoseconds. They are positively correlated with the directional spreads at the base station. Finally, an investigation about the impact of microscopic surface roughness is conducted: it is found that it is mostly negligible at millimeter waves, unless extremely narrow beamwidth antennas are used.","Title: Channel Dynamics In Body Area Networks: Recent Results And Challenges\nYear: 2015\n\nAbstract: Recent results about body area radio channel dynamics are analyzed, considering on-body and body-to-body transmissions. Investigations are based on experimental data around 4 GHz. Regarding the on-body case, the dynamics of cross-channel correlation are measured and analyzed for stationary periodic and non-stationary motions, with a clear impact of the walking mode being observed. For body-to-body scenarios, measurements conducted in room-to-room environments show again some strong non-stationary behaviors. In both cases, Markov chain-based models are developed to represent transitions between fading states.","Title: Reliable communication between rescuers during interventions using textile antenna systems\nYear: 2015\n\nAbstract: The safety of on-duty firefighters in indoor environments could be increased by ensuring reliable, high-data rate communication in potentially life-threatening situations. This increases their situational awareness, strengthens their decision making and decreases response time by ensuring efficient indoor communication of sensor data, biometric data, pictures or videos. Therefore, a real-life rescue operation was replicated by means of two simultaneously moving firefighters in an office environment. These wideband channel sounder measurements were performed at 3.6 GHz with 80 MHz bandwidth. Four Ultra-Wideband Substrate Integrated Waveguide cavity-backed slot textile antennas were integrated in the front, back, left shoulder and right shoulder sections of the firefighters' jackets, providing up to 4×4 MIMO communication. For this indoor environment, we extract the pertinent OFDM parameters using the RMS delay spread and 50% correlation bandwidth of the sixteen individual SISO channels. Furthermore, we calculate the potential SISO-, 2×2 MIMO- and 4×4 MIMO-OFDM capacities and corresponding data rates. Finally, we show that the 4×4 MIMO setup is more energy efficient and increases both the link reliability and link quality.","Title: Vehicle-to-Vehicle Radio Channel Characterization in Crossroad Scenarios.\nYear: 2016\n\nAbstract: Vehicle-to-vehicle (V2V)-communication-based collision avoidance systems detect if two vehicles are on a collision course (e.g., in crossroads, intersections, and highway merging), and they are particularly useful in the absence of line of sight (LOS) owing to buildings, roadside infrastructures, and road bending. Relying on radio measurements using a 4 × 30 multiple-input-multiple-output (MIMO) s...","Title: Physical-Statistical Modeling of Dynamic Indoor Power Delay Profiles.\nYear: 2017\n\nAbstract: This paper presents a physical-statistical radio channel power delay profiles model for room-to-room communication systems combining the room electromagnetic theory for modeling deterministic channel components with a geometry-based stochastic channel model with time-variant statistics for modeling stochastic components. The deterministic channel component, i.e., mean power delay spectrum, is comp...","Title: Stochastic Geometry Based Coverage Estimation Using Realistic Urban Shadowing Models\nYear: 2018\n\nAbstract: The main contribution of this paper consists in integrating a physically correlated shadowing model of the aggregate interference in a stochastic geometry-based approach. The considered shadowing takes place in a Manhattan urban grid and combines both penetration and corner diffraction when modeling signal transmission from base stations to users. A tractable expression for the network coverage probability is obtained thanks to the framework of stochastic geometry. Our results suggest that the diffracted mechanisms are dominant compared to building penetration. It is also shown that the second order diffracted signal have little impact on the coverage compared to the first order signals.","Title: An extension of the RiMAX multipath estimation algorithm for ultra-wideband channel modeling.\nYear: 2018\n\nAbstract: This work presents an extension of the high-resolution RiMAX multipath estimation algorithm, enabling the analysis of frequency-dependent propagation parameters for ultra-wideband (UWB) channel modeling. Since RiMAX is a narrowband algorithm, it does not account for the frequency-dependency of the radio channel or the environment. As such, the impact of certain materials in which these systems operate can no longer be considered constant with respect to frequency, preventing an accurate estimation of multipath parameters for UWB communication. In order to track both the specular and dense multipath components (SMC and DMC) over frequency, an extension to the RiMAX algorithm was developed that can process UWB measurement data. The advantage of our approach is that geometrical propagation parameters do not appear or disappear from one sub-band onto the next. The UWB-RiMAX algorithm makes it possible to re-evaluate common radio channel parameters for DMC in the wideband scenario, and to extend the well-known deterministic propagation model comprising of SMC alone, towards a more hybrid model containing the stochastic contributions from the DMC's distributed diffuse scattering as well. Our algorithm was tested with synthetic radio channel models in an indoor environment, which show that our algorithm can match up to 99% of the SMC parameters according to the multipath component distance (MCD) metric and that the DMC reverberation time known from the theory of room electromagnetics can be estimated on average with an error margin of less than 2 ns throughout the UWB frequency band. We also present some preliminary results in an indoor environment, which indicate a strong presence of DMC and thus diffuse scattering. The DMC power represents up to 50% of the total measured power for the lower UWB frequencies and reduces to around 30% for the higher UWB frequencies.","Title: A Novel Target Recognition Based Radio Channel Clustering Algorithm\nYear: 2018\n\nAbstract: In this paper, a novel target recognition based clustering algorithm is proposed for time-varying channels. Power angle spectrum (PAS) is extracted from measurement data by using Bartlett beamformer. Then the clusters in the PAS are separated from the background by using the proposed algorithm, where the amplitude distribution of the elements in the PAS is considered. Moreover, morphology operations are applied to further divide the clusters which are connected to each other. It is found that, the dominating clusters in both line-of-sight (LoS) and non-line-of-sight (NLoS) environments can be well recognized by the proposed algorithm with low computation cost. By using the proposed algorithm, the dynamic changes of the clusters in real-time channel measurement can be clearly observed, without using any high-resolution parameter estimation.","Title: A Power-Angle-Spectrum Based Clustering and Tracking Algorithm for Time-Varying Radio Channels.\nYear: 2019\n\nAbstract: Radio channel modeling has been an important research topic, since the performance of any communication system depends on channel characteristics. So far, most existing clustering algorithms are conducted based on the multipath components (MPCs) extracted by using a high-resolution parameter estimation approach, e.g., SAGE or MUSIC, etc. However, most of the estimation approaches require prior inf...","Title: Semi-empirical Model of Global Exposure using Stochastic Geometry\nYear: 2021\n\nAbstract: Exposure to electromagnetic fields due to cellular networks in an urban environment is studied using stochastic geometry. We describe a simple but functional and realistic semi-empirical model based on the modeling of base station patterns as Poisson Point Processes and applied to two Brussels municipalities. Using this model, a study of the impact of base station densification is performed accord...","Title: Cluster-Based Characterization and Modeling for UAV Air-to-Ground Time-Varying Channels\nYear: 2022\n\nAbstract: With the deep integration between the unmanned aerial vehicle (UAV) and wireless communication, UAV-based air-to-ground (AG) propagation channels need more detailed descriptions and accurate models. In this paper, we aim to conduct cluster-based characterization and modeling for AG channels. To our best knowledge, this is the first study that concentrates on the clustering and tracking of multipath components (MPCs) for time-varying AG channels. Based on measurement data at 6.5 GHz with a bandwidth of 500 MHz, we first estimate potential MPCs utilizing the space-alternating generalized expectation-maximization (SAGE) algorithm. Then, we cluster the extracted MPCs by employing K-Power-Means (KPM) algorithm under multipath component distance (MCD) measure. For characterizing time-variant clusters, we exploit a clustering-based tracking (CBT) method, which efficiently quantifies the survival lengths of clusters. Ultimately, we establish a cluster-based channel model, and validations illustrate the accuracy of the proposed model. This work not only promotes a better understanding of AG propagation channels but also provides a general cluster-based AG channel model with certain extensibility.","Title: Spatial Loss Field for Outdoor Micro-Cells\nYear: 2022\n\nAbstract: In propagation analysis it is assumed that existing shadowing losses are due to obstacles through the propagation path between two transceivers. Although classically modelled as a log-normal random variable, special attention is being recently put into models where shadowing is considered as a consequence of an Underlying Spatial Loss Field (USLF) accounting for attenuation, under Radio Channel Tomography (RCT) framework. In this paper we address the task of making shadowing predictions for transceiver locations, without the need of measurements for those locations. A spatial loss field estimate is produced from measurements for a given set of transceiver locations, and used as an input to predict the shadowing at another set of transceiver locations. Moreover, new weighting functions are proposed and developed from channel parameter estimates of the propagation paths.","Title: Mm-Wave Massive MIMO Channel Sounding in Industrial IoT Scenarios\nYear: 2022\n\nAbstract: This paper presents results of massive multi-input multi-output (mMIMO) channel characteristics based on measurements carried out in an industrial environment at frequency ranges from 26 GHz to 30 GHz. Three different propagation conditions were considered, i.e. line-of-sight (LOS), obstructed LOS (OLOS) and non-LOS (NLOS), and two types of virtual antenna arrays were measured using monopole antennas, i.e. the planar and cubic arrays composed of 21x21 and 5x5x5 elements, respectively. The main results on large-scale parameters as well as an analysis on specular and dense multi-path components are then presented. Finally, the spatial correlation properties over a large antenna arrays were investigated in LOS and OLOS scenarios."],"string":"[\n \"Title: First- and Second-Order Statistics of On-Body Propagation Channels\\nYear: 2013\\n\\nAbstract: On-body channel dynamics are primarily affected by body motions, which not only cause dynamic scattering conditions but also modify the geometry of links over time. We experimentally investigate the Doppler spectra of narrowband on-body channels at 2.45 GHz in both anechoic and indoor environments. The body dynamics resulting from the motion are shown to directly affect the Doppler spectrum. An empirical model is proposed to describe the global and/or local Doppler spreads. The fit of a 3-cylinder-based physical model accounting for the arm swinging is also evaluated.\",\n \"Title: Tri-polarized MIMO systems in real-world channels: Channel investigation and performance analysis.\\nYear: 2012\\n\\nAbstract: Polarized multi-antenna systems are an effective solution for reducing inter-antenna spacing while still maintaining low inter-antenna correlation. Traditionally, only dual-polarized antenna systems are used for polarized transceivers. In this paper, tri-polarized antenna systems are investigated. Starting from the polarization mechanisms in the wireless propagation channel, it is shown that dual-polarized MIMO systems show high sensitivity to the transmitter and receiver orientation, which may be very critical in practical applications. Tri-polarized MIMO systems are introduced as a solution to obtain a robust MIMO performances, which are independent of the transmitter and receiver orientation. The performances of dual- and tri-polarized MIMO systems are evaluated on real-world measured channels, and the limits of each of these systems is highlighted.\",\n \"Title: Channel Correlations And Capacity Metrics In Mimo Dual-Polarized Rayleigh And Ricean Channels\\nYear: 2004\\n\\nAbstract: This communication highlights the impact of channel correlations, including cross-correlation terms, on various relevant metrics, namely the squared channel Frobenius norm and as well as capacity metrics, directly linked with the channel covariance matrix. Using the developed metrics, we compare various antenna configurations, with a focus on multi-polarized systems. Several orthogonal schemes, such as horizontal-vertical and slant schemes, are investigated, and analytical expressions are presented.\",\n \"Title: Fast Fading Characterization for Indoor to Indoor and Outdoor to Indoor Channels.\\nYear: 2011\\n\\nAbstract: This work models the fast fading characteristics in indoor to indoor and outdoor to indoor channels at 3.8 GHz. Starting from real world measurements, the fast fading characteristics are extracted and properly modeled, taking into account the nodes movement conditions. For static environments, the fast fading is modeled with the well known Ricean distribution. As expected the K-factor depends on the path loss. On the other hand, in mobile environments, the probability density function of the signal envelope is accurately described by the recently developed second-order scattering fading (SOSF) distribution. The SOSF distribution combines the Rayleigh, Ricean and double Rayleigh fading and any linear combinations of these. Our results show that the higher the mobility, the more severe is the fading.\",\n \"Title: Spatial separation of multi-user MIMO channels\\nYear: 2009\\n\\nAbstract: Since multi-antenna (MIMO) systems are becoming more popular thanks to their inherent potential for capacity improvement, interference from MIMO transceivers is an in- creasingly serious concern. Spatial multiplexing schemes are particularly vulnerable to multi-user interference. Fortunately, this interference can be mitigated, when the channel matrices show a sufficient spatial separation. In this paper, we quantify the separability of multi-user MIMO channels using actual measurements in a scenario where a single outdoor base station transmits to two indoor mobile receivers. To quantify the spatial distance between the two users, we compare the spatial correlation matrices using two simple measures: (i) matrix collinearity, and (ii) the condition number ratio. Both measures are directly linked to MIMO system performance. Our measurement-based evaluations demonstrate that the downlink channels of different users can have a significantly different spatial structure, even when the users are in the same room. This leads to the following conclusions: (i) new multi-user MIMO models are needed to describe the spatial characteristics of different users, and (ii) spatial interference can be well managed by appropriate scheduling and precoding algorithms.\",\n \"Title: Accuracy of depolarization and delay spread predictions using advanced ray-based modeling in indoor scenarios\\nYear: 2011\\n\\nAbstract: This article investigates the prediction accuracy of an advanced deterministic propagation model in terms of channel depolarization\\n and frequency selectivity for indoor wireless propagation. In addition to specular reflection and diffraction, the developed\\n ray tracing tool considers penetration through dielectric blocks and/or diffuse scattering mechanisms. The sensitivity and\\n prediction accuracy analysis is based on two measurement campaigns carried out in a warehouse and an office building. It is\\n shown that the implementation of diffuse scattering into RT significantly increases the accuracy of the cross-polar discrimination\\n prediction, whereas the delay-spread prediction is only marginally improved.\",\n \"Title: Analytical Multi-User MIMO Channel Modeling: Subspace Alignment Matters.\\nYear: 2012\\n\\nAbstract: For a receiver that observes a mixture of desired and interfering multiple-input multiple-output (MIMO) transmissions, not all interference has the same severity: its effect is modulated by the degree of alignment between the eigenspaces of the desired and undesired channel matrices.An analytical channel model is proposed to account for this effect. Two metrics of eigenspace compatibility are studied, and a method to generate channels of a given degree of compatibility is derived. The resulting model is parameterized using radio channel measurement data, and an implementation recipe for immediate use of the model is provided.\",\n \"Title: Modeling Time-Variant Fast Fading Statistics of Mobile Peer-to-Peer Radio Channels\\nYear: 2011\\n\\nAbstract: The radio channels between nodes of an indoor peer-to-peer network show specific fast fading characteristics. Depending on the mobility and on the scattering properties of the environment, different kinds of fading distributions can occur: Ricean fading between static nodes, but also Rayleigh or even double-Rayleigh fading between mobile nodes. We investigate fast fading in indoor peer-to-peer networks based on radio channel measurements. It turns out that the fading statistics change over time. While the predominant fading mechanism is a combination of Rayleigh and double-Rayleigh fading, Ricean fading also occasionally occurs. On top of that, indoors, the statistics of the fast fading change over time even for small-motions of the nodes, since the propagation environment is inhomogeneous. We comprehensively model these effects using a hidden Markov model, parameterized from our measurements. The model is validated, revealing a convincing fit between the model and the measurements.\",\n \"Title: Mutual Coupling Effects On The Channel Capacity And The Space-Time Processing Of Mimo Communication Systems\\nYear: 2003\\n\\nAbstract: The channel capacity and the performance of MIMO systems in the presence of fading correlation and antenna coupling are investigated. Simulation results demonstrate that mutual coupling can improve the performance depending on the inter-element spacing and the richness of scattering. It is shown that the bit error rate performance of spatial multiplexing is particularly influenced by the decorrelation/correlation effect caused by mutual coupling. On the other hand, the bit error rate performance of transmit diversity is mainly affected by the resulting modification of antenna gain-and received power.\",\n \"Title: A ray tracing algorithm using the discrete prolate spheroidal subspace\\nYear: 2013\\n\\nAbstract: Ray tracing (RT) is an accurate propagation prediction tool that has been widely used to simulate channel characteristics in indoor environments. To date, the developed RT tool includes not only specular reflection, penetration through dielectric blocks and diffraction, but also diffuse scattering mechanisms. The accuracy, provided by a detailed modeling of the environment, comes at the cost of a high computational complexity, which directly scales with the number of propagation paths considered. We are interested in simulating the radio propagation conditions for a mobile terminal, communicating in a frame based communication system indoors with several fixed nodes. This communication shall be used to obtain the position of the mobile terminal in indoor scenario. Therefore, the correlated temporal and spatial evolution of the channel impulse response is of utmost concern. In this paper, we propose a method to significantly reduce the computational complexity of RT by using a projection of all propagation paths on a subspace spanned by two-dimensional discrete prolate spheroidal (DPS) sequences. With this method the computational complexity can be reduced by more than one order of magnitude for indoor scenarios. The accuracy of our low-complexity DPS subspace based RT algorithm is verified by numeric simulations.\",\n \"Title: An Analytical Modeling of Polarized Time-Variant On-Body Propagation Channels with Dynamic Body Scattering\\nYear: 2011\\n\\nAbstract: On-body propagation is one of the dominant propagation mechanisms in wireless body area networks (WBANs). It is characterized by near-field body-coupling and strong body-scattering effects. The temporal and spatial properties of on-body channels are jointly affected by the antenna polarization, the body posture, and the body motion. Analysis on the time variant properties of on-body channels relies on a good understanding of the dynamic body scattering, which is highly dependent on specific scenarios. In this paper, we develop an analytical model to provide a canonical description of on-body channels in both time and space domains to investigate the on-body propagation over the trunk surface of a walking human. The scattering from the arms and the trunk in different dimensions is considered with a simplified geometrical description of the body and of the body movements during the walk. A general full-wave solution of a polarized point source with multiple cylinder scattering is derived and extended by considering time evolution. The model is finally validated by deterministic and statistical comparisons to different measurements in anechoic environments.\",\n \"Title: A New Double-Directional Channel Model Including Antenna Patterns, Array Orientation, and Depolarization\\nYear: 2010\\n\\nAbstract: Multiple-input-multiple-output (MIMO) wireless channel models are often too simplistic to accurately model wireless propagation effects or too complex and/or site specific to be used for analytical purposes. In this paper, we develop a double-directional MIMO channel model that accounts for important propagation effects like scattering, clustering, and channel depolarization and antenna effects like antenna diversity, cross polarization, and random array orientation, while still retaining an intuitive representation. The proposed model can be parameterized using channel measurements obtained from site-specific measurement campaigns or from standard-based channel models. We show, using simulations, that the proposed model captures channel and antenna effects not included in other models, like the third-generation partnership program (3GPP) spatial channel model, the WINNER, and the IEEE 802.11n channel model. We use the model to study the impact of random orientation and channel depolarization on the data rates of a MIMO system.\",\n \"Title: Channel Correlation And Cross-Polar Ratio In Multi-Polarized Mimo Channels: Analytical Derivation And Experimental Validation\\nYear: 2008\\n\\nAbstract: This paper proposes a closed-form expression for the correlation coefficient and the cross-polarization discrimination (XPD) of a randomly oriented dual-or tri-polarized MIMO system. The environment is supposed to have a truncated Laplacian power azimuth spectrum that is widely used in standardization bodies. Correlation and XPD are shown to be highly sensitive to receiver orientation, azimuth spread and environment depolarization behavior. Measurements were conducted at 3.5 GHz to validate the theoretical model. Good agreement is obtained between theoretical curves and experimental results for correlation and XPD when comparing at different receiver orientations.\",\n \"Title: Mutual Information And Error Probability Of Dual-Polarized Systems\\nYear: 2007\\n\\nAbstract: In this communication, we address the potential benefits of dual-polarized arrays in 2 x 2 MIMO systems. We start with a new and simple analytical model of dual-polarized Rayleigh and Ricean fading channels, which relies on a limited number of physical parameters, such as the spatial correlations, the co-polar gain imbalance and the cross-polar discrimination. Then, we investigate the multiplexing advantage of dual-polarized transmissions through the evaluation of the ergodic mutual information. Finally, the performance of two space-time coding schemes (Alamouti O-STBC and uncoded Spatial Multiplexing) is evaluated via a detailed analysis of the pairwise error probability.\",\n \"Title: Indoor Wireless Communications With Multiple Antennas And Polarizations: From Channel Characterization To Performance Simulation\\nYear: 2008\\n\\nAbstract: In this paper, we describe experimental results characterizing the frequency/space/polarization selectivity of indoor channels at 1.9 GHz. Regarding the delay-angle dispersion, a clustered geometry-based model is developed from measurement results and validated. Regarding dual-polarized channels, a simple analytical model is extracted from experimental data, accounting for the cross-correlation between the various parameters. Finally, narrowband dual-polarized and single-polarized transmissions are compared in real-world indoor channels based on performance metrics for multiplexing and diversity gains.\",\n \"Title: Empirical Investigation Of Multi-Link Separation For Indoor Mimo Channels\\nYear: 2011\\n\\nAbstract: Based on multi-node multi-antenna channel measurements in a multi-wall office environment, we estimate the degree of separation between multiple MIMO links by means of two metrics: the correlation matrix distance and the shadowing correlation. Both nomadic and mobile node scenarios are considered and compared. Empirical models are eventually derived. Our analysis reveals that the average separation between two MIMO links sharing a joint transmitter is usually lower in mobile scenarios than in nomadic scenarios, and is strongly related to the spatial correlation of the individual MIMO links. However, there appears to be no relationship between the correlation matrix distance and the shadowing correlation.\",\n \"Title: Modeling Outdoor Macrocellular Clusters Based on 1.9-GHz Experimental Data\\nYear: 2007\\n\\nAbstract: This paper presents a stochastic geometry-based model of the multiple-input-multiple-output channel, as seen by the user terminal based on the extraction of cluster parameters from wideband data measured at 1.9 GHz in short-range outdoor macrocellular environments. Clusters are first identified through data visual inspection. Then, a statistical characterization is carried out based on a delay-ori...\",\n \"Title: Robust Signal Constellations For Spatial Multiplexing In The Presence Of Real Fading Propagation Channels\\nYear: 2003\\n\\nAbstract: Spatial multiplexing is employed in MIMO communication systems to increase spectral efficiency. The performance of spatial multiplexing is highly dependent on the propagation conditions such as the richness of scattering, the presence of dominant components and the inter-element spacings. In this paper, new robust signal constellations for use in spatial multiplexing over real fading propagation channels are developed. It is shown that these new constellations are by far more robust against fading correlations and high Rice factor than the classical PSK and QAM constellations. With these new constellations, spatial multiplexing presents excellent symbol error rate performance whatever the propagation environment and the inter-element distance.\",\n \"Title: The COST 2100 MIMO channel model\\nYear: 2012\\n\\nAbstract: The COST 2100 channel model is a geometry- based stochastic channel model (GSCM) that can reproduce the stochastic properties of MIMO channels over time, frequency, and space. In contrast to other popular GSCMs, the COST 2100 approach is generic and flexible, making it suitable to model multi-user or distributed MIMO scenarios. In this article a concise overview of the COST 2100 channel model is presented. Main concepts are described, together with useful implementation guidelines. Recent developments, including dense multipath components, polarization, and multi-link aspects, are also discussed.\",\n \"Title: Tri-polarized spectrum sensing based on an experimental outdoor-to-indoor cognitive-radio scenario.\\nYear: 2012\\n\\nAbstract: Compared to classical spatially separated multiple antenna system, cross-polarized co-located antenna systems are an interesting way to reduce equipment size while reducing the inter-antenna correlation. In this paper the spectrum sensing of a Cognitive Radio (CR) system taking advantage of polarization diversity under Rayleigh fading is investigated and compared to an equivalent system using spatial diversity. This analysis is based on a theoretical formulation applied to a real-world scenario. For this purpose, an outdoor-to-indoor measurement campaign at a frequency of 3.5 GHz is realized, where an indoor secondary user senses the signals received from an outdoor primary base station. The signals received at each antenna are first combined and then applied to an energy detector. The theoretical expressions are simulated in the measurement context. The detection probability behavior as a function of distance between the Primary Transmitter (PTx) and the Secondary Terminal (STE) and the inter-antenna correlation effect on the sensing performance are studied.\",\n \"Title: A Study On Polarimetric Properties Of Scattering From Building Walls\\nYear: 2010\\n\\nAbstract: The polarimetric characteristics of the signal back scattered from a building wall are studied in this paper with the aid of MIMO measurements and Ray Tracing simulation. A very simple environment with a single rural building amid an open area is considered to reduce complexity and better isolate the different kinds of back-scattered contributions: specular reflection, diffractions, diffuse scattering. Narrowband and wideband metrics are utilized to evaluate scattering characteristics focusing in particular on its polarization properties.\",\n \"Title: Performance Evaluation of Interference Bound Backhaul Links in High Capacity Wireless Networks\\nYear: 2014\\n\\nAbstract: An innovative architecture employing wireless backhaul in hierarchical wireless networks is considered in this paper to provide high throughput densities. Multi-beam antennas, combined with aggressive frequency reuse have recently been exploited to increase the throughput density in densely deployed wireless networks. However, large number of narrow beams cause not only co-channel interference but also inter-cell interference. To mitigate this problem, amplitude tapering in multi-beam antennas is investigated in this paper. Results show that tapered beams significantly improve the carrier to interference ratio from 5 to 8 dB and consequently achieve downlink throughput density over 0.65 Gbps/km$$^2$$2. An overall throughput density of 1.2 Gbps/km$$^2$$2 is expected when taking both up- and downlinks into account.\",\n \"Title: A Spatially-Correlated Tapped Delay Line Model For Body Area Networks\\nYear: 2008\\n\\nAbstract: Using wireless sensors worn on the body for pervasive monitoring is expected to become more and more common in the next years. The achievement of this application requires solving some challenges, especially in the power saving domain. In order to develop efficient power radio communications, an interesting investigation field is the multi-sensor MIMO (MS-MIMO) ultra-wideband (UWB) network. It is realistic to assume that each sensor carries one antenna, while the central device uses an antenna array. In this paper, a new analytical channel model for the diffracted waves mechanism is proposed. It is derived from the existing IEEE 802.15.4a standard channel model and innovates with space-time considerations.\",\n \"Title: Design issues for MIMO systems in various fading situations\\nYear: 2006\\n\\nAbstract: This contribution provides a fresh look at the asymptotic (in terms of number of antennas) design of multiple-antenna wireless systems, with the goal of giving useful insights on the deployment of future MIMO systems. For the i.i.d. Gaussian and double-directional models, we provide guidelines in terms of the repartition of the antennas between the transmitter and the receiver, and study the influence of array geometry on the ergodic mutual information per antenna. Furthermore, we compare the LOS and NLOS situations, and evaluate the relative importance of the LOS component and path loss in Ricean fading, as well as in the low-rank Ricean component case.\",\n \"Title: Space-Time Code Design for Correlated Ricean MIMO Channels at Finite SNR\\nYear: 2008\\n\\nAbstract: Space-time code (STC) designs commonly rely on the assumptions of independent and identically distributed (i.i.d.) Rayleigh channels (being either slow or fast fading) and high signal-to-noise ratio (SNR). However, it has been shown that poor scattering conditions can have detrimental effects on the performance of STCs and that the behavior of codes at high SNR is radically different from the fini...\",\n \"Title: A Time-Variant Statistical Channel Model For Tri-Polarized Antenna Systems\\nYear: 2010\\n\\nAbstract: Polarized MIMO systems are an efficient solution for reducing inter-antenna correlation while maintaining compact terminal size. In this paper, a time-variant statistical channel model is proposed for tri-polarized antenna systems. The model is based on a coherent and a scattered component, where each component includes inter-channel correlation and cross-polar discriminations. The temporal variations of the channel are separated in slow and fast channel variations. A measurement campaign has been performed at 3.6 GHz to parameterize the model, in both static and mobile cases. A variant of the variogram technique has been adopted for extracting the slow-varying channel parameters. Experimental results are investigated and presented. The Doppler spectrum of the fast channel variations show fundamental differences between the static case and the mobile case. Finally, it is explained how the proposed model can be generated.\",\n \"Title: Low-complexity sub-band divided ray tracing for UWB indoor channels\\nYear: 2014\\n\\nAbstract: Ray tracing has been extensively used to simulate indoor channel characteristics. For an ultra-wideband system, the channel characteristics vary significantly over the entire bandwidth. To cope with this, sub-band divided RT has been proposed by dividing the frequency of interest into multiple subbands and superposing the RT results at the individual center frequency of each subband. Thus, the computational complexity is directly proportional to the number of subbands. In this paper, we propose a mathematical method to significantly reduce the computational complexity of the sub-band divided RT, making it almost independent of the number of subbands. It is important to note that, based on our approach, not only the determination of the rays reaching a give location is made only once, but also the electromagnetic calculation of the received signal is not needed to perform repeatedly. The accuracy of low-complexity subband divided RT algorithm is verified through a measurement campaign.\",\n \"Title: Calibration of indoor UWB sub-band divided ray tracing using multiobjective simulated annealing\\nYear: 2014\\n\\nAbstract: Sub-band divided ray tracing (RT) has been widely used to reproduce as reliably as possible the ultra-wideband (UWB) radio wave propagation channel in realistic indoor environments. However, its accuracy is strictly limited by the available description of the environment. Moreover, its computational complexity scales with the number of selected subbands and the number of propagation paths. In the present work, our RT tool considers not only deterministic propagation paths but also diffuse scattering components. Based on a low-complexity sub-band divided RT implementation, we propose a calibration method for indoor UWB sub-band divided RT. The method estimates the optimal material parameters, including the dielectric parameters and the scattering parameters, using channel measurements and multiobjective simulated annealing (MOSA). This calibration can improve the accuracy of sub-band divided RT in terms of the power delay profile (PDP) and the root mean square (RMS) delay spread for all test locations including those not considered by the calibration. A measurement campaign is used to verify the calibration technique.\",\n \"Title: On the use of ray tracing for performance prediction of UWB indoor localization systems\\nYear: 2013\\n\\nAbstract: The most important factors impairing the performance of radio-based indoor localization systems are propagation effects like strong reflections or diffuse scattering. To the full extent, these effects can be captured only by time-consuming measurement campaigns. Ray tracing (RT) offers the possibility to predict the radio channel for a certain environment, avoiding the need for measurements. However, it is crucial to include all relevant propagation mechanisms in the RT as well as to validate the obtained results. In this paper, we analyze if sub-band divided RT can yield realistic ultra-wideband channel impulse responses. We use the RT results for performance analysis of multipath-assisted localization, which depends directly upon the above mentioned propagation effects. In particular, it has been shown that the ratio of the signal energies of deterministically reflected paths to interfering diffuse components quantifies the amount of position-related information of deterministic multipath components. Comparison of this ratio to measurement data is thus useful to validate the sub-band divided RT. The results highlight the need for proper modeling of the diffuse multipath, as estimates of this energy ratio using RT are often overly optimistic. However, the obtained localization performance predictions using measurements and RT show general agreement.\",\n \"Title: Shadow Fading Correlation in High-Speed Railway Environments\\nYear: 2015\\n\\nAbstract: In the design of diversity and fast handover schemes for high-speed railways (HSRs), a better understanding of the shadow fading correlation properties is required. In this paper, both auto- and cross-correlation models of shadow fading in HSR environments are proposed based on a large set of measurements with 6146 cells in China. The measurements are conducted using a practically deployed and operative GSM-Railway (GSM-R) system at 930 MHz, to reflect the real conditions of shadow fading in the HSR environments. 7 typical HSR environments and the realistic base station (BS) parameters are considered in the analysis. It is found that the decorrelation distance is correlated with the standard deviation of shadow fading, and is generally larger than 100 m in most of HSR environments. The cross-correlation of shadow fading between two neighboring BSs dependents on the BS height and the tilt angle of the antenna, and a heuristic truncated Gaussian distribution model of cross-correlation is proposed. The model is validated by the measurements conducted in another operative HSR line. The results can be used to exploit the simulation algorithms, to analyze the signal-to-interference-ratio (SIR) properties, and to develop new and better handover schemes for HSRs.\",\n \"Title: A stochastic geometrical vector model of macro- and megacellular communication channels\\nYear: 2002\\n\\nAbstract: This paper describes a physically based stochastic approach that allows to predict the narrowband fading statistics for macro- and megacellular networks operating in urban areas. On one hand, macrocellular channels have been mainly covered in the literature by means of empirical models. On the other hand, megacells are typical of upcoming communication systems, such as broadband wireless access and high-altitude platform-based net- works. Generally, the path gain of a wireless fading channel can be statistically characterized by a Ricean distribution, which includes Rayleigh fading as a particular case. The key parameter of the dis- tribution is the -factor , defined as the ratio of the dominant component to the scatter contribution. In this paper, the -factor is estimated by means of a physical model, conditionally to a set of geometrical parameters, such as the building height, the street width and the base station-to-terminal distance. These parameters are statistically described by analytical distributions. The model is successfully compared with experimental data at 1.6 GHz and typical applications are presented. Finally, because of its physical background, the model performs very well in analyzing polariza- tion (MIMO) multiplexing schemes.\",\n \"Title: Wide-band SIMO 1×2 measurements and characterization of outdoor wireless channels at 1.9 GHz\\nYear: 2004\\n\\nAbstract: This paper aims at characterizing the spatial wireless channel at 1.9 GHz, based on a 1×2 measurement chain. A typical campus/residential area and an industrial area have been investigated. The measurement equipment is constituted by an 80-MHz transmitter at 1.9 GHz, located at the top of a building. At the receiver, two omnidirectional antennas are connected to a wide-band channel sounder through a switch in order to measure an estimate of the instantaneous vector channel. It is found that the Ricean K-factor and the delay spread are lognormally distributed, while the azimuth spread at the receive side follows a Gaussian distribution. The range dependence of various parameters are pointed out and compared with empirical models. The impacts of antenna spacing and array orientation on the channel correlation are highlighted and compared to theoretical simulation results. Finally, the cross-correlation properties between K-factor, delay spread, azimuth spread, and channel correlation are analyzed.\",\n \"Title: Mutual information of non-Kronecker structured dual-polarized 2×2 channels\\nYear: 2006\\n\\nAbstract: This paper investigates the mutual information of several 2×2 systems using orthogonal polarizations. Analytical approximations of the mutual information in equi-power allocation scenarios are derived and compared in both Rayleigh and Ricean fading conditions.\",\n \"Title: Validity of the Kronecker Model for MIMO Correlated Channels\\nYear: 2006\\n\\nAbstract: The goal of this paper is to investigate the validity of the Kronecker model for MIMO correlated channels. First, mathematical and equivalent propagation conditions of validity are detailed. In a second part, we address several areas where the Kronecker model is not valid. We also review the one-ring model and experimental results dealing with the validation of the Kronecker model. Based on these scarce results, the preliminary conclusion is that the Kronecker model might not be valid for arrays larger than 2times2 when antenna correlations are high across both receive and transmit arrays. The paradox is that the Kronecker model has been developed and is being widely used to account for correlation. This is in strong contrast with the popular belief that the Kronecker model is valid in many indoor and outdoor cases\",\n \"Title: Impact of Antenna Coupling on 2 × 2 MIMO Communications\\nYear: 2007\\n\\nAbstract: The impact of mutual coupling induced by two closely spaced minimum scattering antennas at the subscriber unit on 2 times 2 multiple-input multiple-output channels and communications is investigated. Both (de)correlation effects and variations of antenna gain resulting from coupling mechanisms are considered. Relationships between coupling and correlations/channel Frobenius norm are discussed, pointing out the role of the interelement spacing, the array orientation, and the richness of scattering. The analysis also yields useful insight into the influence of mutual coupling on capacity and system performance\",\n \"Title: Multi-Polarized MIMO Communications: Channel Model, Mutual Information and Array Optimization\\nYear: 2007\\n\\nAbstract: This paper considers the use of nr times nt dual-polarized arrays for improving the mutual information of MIMO communications. We first develop an elegant model of the multi-polarized MIMO channel, which allows to account for spatial correlation and depolarization effects. The major advantage of the model lies in its analytical expression, whose parameters have a clear physical meaning. In a second part, we investigate the ergodic mutual information of multi-polarized schemes, and derive a condition upon which multi-polarized transmissions offer a higher capacity than equivalent uni-polarized schemes using the same number of antennas under the same overall array dimensions.\",\n \"Title: Wideband MIMO Car-to-Car Radio Channel Measurements at 5.3 GHz\\nYear: 2008\\n\\nAbstract: Measurements of car-to-car (C2C) radio channels with 60 MHz bandwidth at 5.3 GHz have been performed in Helsinki, Finland. We focused on 30x30 multiple-input multiple- output (MIMO) measurements, conducted in four environments (urban, sub-urban, campus and highway), under quasi-realistic traffic conditions. As first results, we present in this paper the delay spread statistics for each investigated environment. The largest values of root-mean-square (RMS) delay spread, roughly 2 mus, were obtained in the urban environment. The narrowband channel fading statistics have also been derived using composite distributions, in order to assess the global fading statistics.\",\n \"Title: Analytical model and experimental validation of cross polar ratio in polarized MIMO channels\\nYear: 2008\\n\\nAbstract: Cross-polarized antenna systems are used to reduce equipment size in MIMO systems while still achieving low inter-antenna correlation. One fundamental parameter of cross-polarized MIMO systems is the cross-polar discrimination (XPD). This paper proposes a model to determine the XPD as a function of channel condition and under different antenna configurations. The environment is supposed to have a truncated Laplacian Power Angular Spectrum (PAS) that is widely used in standardization bodies. Antenna XPD is shown to be sensitive to different channel conditions, as well as to different receiver orientations. Measurements were conducted at 3.5 GHz to validate the theoretical model. Good agreement is obtained between theoretical XPD and experimental results.\",\n \"Title: Radio Channel Characterization for Moderate Antenna Heights in Forest Areas\\nYear: 2009\\n\\nAbstract: This paper describes the results achieved by an experimental campaign whose goal was to characterize the directional propagation channel at 1.9 GHz in forested areas for moderate antenna heights. These experimental results are useful in the context of pedestrian radio-localization systems relying on cellphone signals. Wideband experimental results, which are recorded with transmit-to-receive distances ranging from 40 to 110 m, indicate that the path loss is well modeled by ITU-R Recommendation 833-4. The temporal fading and multipath dispersion are also analyzed. The delay spread, which ranges from 60 to 120 ns, is strongly anticorrelated with the temporal coherence and increases with transmit-to-receive distance. The azimuth spread remains limited, with average values of about 15deg.\",\n \"Title: Polarimetric Measurements for Spatial Wideband MIMO Channels\\nYear: 2009\\n\\nAbstract: This paper investigates the polarization behaviour of indoor multi-polarized MIMO channels at 3.6 GHz. Measurements have been carried out in non-line-of-sight (NLOS) and line-of-sight (LOS) using a dual-polarized transmitter and a tri-polarized receiver. The spatial and delay characteristics are extracted using a per-tap beamforming algorithm. Distinct waves are isolated and the polarization of each wave is expressed in terms of its spherical components. The evolution of the waves polarization is investigated as function of its physical propagation parameters. The polarization of the waves is shown to be sensitive to spatial characteristics, while being insensitive to delay. Direct line-of-sight rays show to have higher XPD than in the NLOS case, while the reflected rays have a similar XPD than in a NLOS case.\",\n \"Title: CRBs for UWB Multipath Channel Estimation: Impact of the Overlapping Between the MPCs on MPC Gain and TOA Estimation\\nYear: 2009\\n\\nAbstract: In this paper we study the impact of the overlapping between neighboring MPCs (multipath component) on the performance of channel estimation. We consider IR-UWB (impulse radio) signals, and the IEEE802.15.3a and IEEE802.15.4a UWB channel models. We show that for a pulse width (PW) sufficiently smaller than the average MPC rate of arrival (ROA) the probability to have more than three overlapping MPCs is relatively small. We derive the CRBs (Cramer Rao bound) for the joint estimation of the MPC gain and TOA (time of arrival) in the case of up to three overlapping MPCs. We compute also the average CRBs. We show that the CRBs obtained by averaging more than 80% of possible cases of the channel, are very close to the bounds obtained under the non-overlapping assumption (NOLA).\",\n \"Title: Polarization measurements and modeling in indoor NLOS environments\\nYear: 2010\\n\\nAbstract: Cross-polarized antenna systems are an attractive way to reduce equipment size while maintaining low interantenna correlation. In this paper, the polarization behaviour of indoor channels is investigated. A measurement campaign has been conducted at 3.6 GHz for a dual-polarized transmitter and a tri-polarized receiver in a non-Line-of-Sight (NLOS) scenario. The spatial and delay characteristics are extracted using a pertap beamforming algorithm. Distinct paths are isolated and the polarization of each wave is expressed in terms of its spherical components. The cross-polarization discrimination (XPD) of the wave is investigated as a function of its physical propagation parameters. The XPD of the wave is shown to be sensitive to spatial characteristics, while being insensitive to delay.\",\n \"Title: Wideband Measurement-Based Modeling of Inter-Vehicle Channels in the 5-GHz Band\\nYear: 2013\\n\\nAbstract: In this paper, we describe a new wideband single-input-single-output (SISO) channel model for vehicle-to-vehicle (V2V) channels, based on an extensive measurement campaign carried out at 5.2 GHz around Helsinki, Finland, in August 2007. Both the currently well-known non-stationary behavior and the measured characteristics of the V2V channel motivate the use of a geometry-based stochastic channel modeling (GSCM) approach rather than a classical tapped delay line (TDL) approach. For the time-variant contributions stemming from discrete scatterers, the propagation distance can be deterministically estimated (i.e., geometrically), whereas the fading can be modeled as the combination of a distance-decaying process and two stochastic small- and large-scale processes. The complete parameterization of the V2V wideband channel model, the recipe for its implementation, and the analysis of its validity are also provided in this paper.\",\n \"Title: Empirical Modeling of Nomadic Peer-to-Peer Networks in Office Environment\\nYear: 2011\\n\\nAbstract: We experimentally characterize nomadic peer-to peer channels in a multi-wall indoor office environment. In particular, we derived models of path-loss, shadowing and fading statistics at 3.8 GHz in fixed scenarios, and compare them with existing results. Highlights of the paper include a multi-wall path loss model, the separation between obstruction, nomadic, and dynamic shadowing, a dynamic shadowing correlation model, as well as a multi-link analysis of MIMO links.\",\n \"Title: Non-Stationary Narrowband MIMO Inter-Vehicle Channel Characterization in the 5-GHz Band\\nYear: 2010\\n\\nAbstract: In this paper, we describe measurements and models of 30 × 30 narrowband multiple-input-multiple-output (MIMO) vehicle-to-vehicle (V2V) radio propagation channels at 5.3 GHz. Four environments were considered: a campus, a highway, a suburban area, and an urban area. Since the scattering environment may rapidly change in V2V communications, we first investigate the validity of the wide-sense stationarity (WSS) assumption for such channels using the correlation matrix distance (CMD), which is a metric for the characterization of the MIMO channel nonstationarity. Moreover, statistical channel models were developed for these environments, which take into account the non-stationary behavior of the measured V2V channels. The large-scale fading was found to be lognormally distributed, whereas the small-scale fading was characterized by the flexible Weibull distribution. Finally, the non-stationary behavior of both large-scale fading and small-scale fading statistics was investigated.\",\n \"Title: Clustered channel characterization for indoor polarized MIMO systems\\nYear: 2009\\n\\nAbstract: A cluster-based channel model is presented that includes polarization characteristics. Measurements have been carried out in an indoor environment at 3.6 GHz using a dual-polarized transmitter and a tri-polarized receiver. Individual propagation paths are extracted using the SAGE algorithm, and a cross-polar discrimination (XPD) per ray is defined. Clusters are identified in the co-elevation-azimuth-delay domain, with an automatic clustering algorithm. The cluster properties are investigated and polarization characteristics are identified on a per-cluster basis. Finally, the obtained model is simulated and extraction-independent parameters are compared with experimental parameters for validation.\",\n \"Title: Capacity performance of outdoor-to-indoor relay schemes in measured radio channels\\nYear: 2009\\n\\nAbstract: In this paper, the capacity of several outdoor-to-indoor relay schemes has been investigated using real-world measurements at 2.45 GHz. The considered scenario encompasses an outdoor base station, possibly using multiple antennas, communicating via two hops to distributed single antenna terminals located inside a building. The single-antenna relays are located along the so-called best wall. Capacity results show that in most cases, relaying techniques increase the capacity, even when constraining the global power expense of the network. Considering a combining scheme using the source-to-destination in addition to the relay link does not bring huge benefits for the measured outdoor-to-indoor channels. The best performance is obtained in a relay-and-forward scheme using multiple cooperative relays.\",\n \"Title: A Polarized Clustered Channel Model for Indoor Multiantenna Systems at 3.6 GHz\\nYear: 2010\\n\\nAbstract: Multiple-input-multiple-output (MIMO) technologies allow high data rates to be obtained, but they suffer from interantenna correlation caused by the limits in interantenna spacing. Polarized MIMO systems resolve this problem by using colocated perpendicularly polarized antennas that have low interantenna correlation. In this paper, a polarized single-directional channel model for 2×N MIMO systems at 3.6 GHz in an indoor environment is presented. The wireless channel is modeled as a sum of clusters, where each cluster has specular and diffuse components. The polarization of the specular component of the clusters is included by considering a per-path polarization. The diffuse component of the clusters is modeled with a Fisher-Bingham (FB5) spectrum in the azimuth-coelevation domain and with an exponential power delay profile. Polarization is analyzed by introducing the cross-polar discrimination of the exponential power delay profile parameters. All of the parameters in the model are extracted from an experimental measurement campaign performed in an indoor environment at 3.6 GHz. Individual paths are extracted from the measurements with the space-alternating generalized expectation-maximization (SAGE) algorithm. These paths are grouped in clusters within the azimuth of arrival-elevation of arrival-delay domains at the receiver side using automatic clustering algorithms. The specular component properties of the clusters are then determined. Finally, the diffuse components of the clusters are investigated and parameterized by applying a beamforming algorithm on the diffuse part of the impulse response.\",\n \"Title: Statistical Characterization of Dynamic Multi-Path Components for Vehicle-to-Vehicle Radio Channels\\nYear: 2015\\n\\nAbstract: To statistically model time-variant vehicle-to-vehicle (V2V) channels, the dynamic multi-path components (MPCs) are characterized based on suburban measurements conducted at 5.3 GHz. The correlation matrix distance (CMD) is used to determine the size of local wide-sense stationary (WSS) region. Within each WSS time window, MPCs are extracted using wideband spatial spectrum of Bartlett beamformer. A MPC distance (MCD)-based tracking algorithm is used to identify the \\\"birth\\\" and \\\"death\\\" of MPCs over different WSS regions, and the lifetime of MPC is modeled with a truncated Gaussian distribution. Distributions of number of MPCs and their positions are statistically modeled. The MPC characterization considers both angular and delay domain properties as well as the dynamic evolution of MPCs over different WSS regions. The results shows insight into the dynamic behaviors of MPCs in V2V environments, and is useful for the scatterer modeling in the geometry-based stochastic channel modeling.\",\n \"Title: Centimeter- and Millimeter-Wave Channel Modeling Using Ray-Tracing for 5G Communications\\nYear: 2015\\n\\nAbstract: A ray-tracing tool, including specular reflection, diffraction and attenuation by foliage, is experimentally validated at 12 and 30 GHz in a suburban environment. The tool is then applied to double directional channel modeling at 30 GHz in a real-world urban area in downtown Brussels. Azimuth-, elevation- and delay-spread are computed and analyzed on a stochastic viewpoint. It is found that elevation spreads remain limited (below 3 degrees), while azimuth-spreads are on average similar at both sides of the link (with a mean value of 12 degrees). Delay-spreads vary significantly over the user's locations, with a mean value of 45 nanoseconds. They are positively correlated with the directional spreads at the base station. Finally, an investigation about the impact of microscopic surface roughness is conducted: it is found that it is mostly negligible at millimeter waves, unless extremely narrow beamwidth antennas are used.\",\n \"Title: Channel Dynamics In Body Area Networks: Recent Results And Challenges\\nYear: 2015\\n\\nAbstract: Recent results about body area radio channel dynamics are analyzed, considering on-body and body-to-body transmissions. Investigations are based on experimental data around 4 GHz. Regarding the on-body case, the dynamics of cross-channel correlation are measured and analyzed for stationary periodic and non-stationary motions, with a clear impact of the walking mode being observed. For body-to-body scenarios, measurements conducted in room-to-room environments show again some strong non-stationary behaviors. In both cases, Markov chain-based models are developed to represent transitions between fading states.\",\n \"Title: Reliable communication between rescuers during interventions using textile antenna systems\\nYear: 2015\\n\\nAbstract: The safety of on-duty firefighters in indoor environments could be increased by ensuring reliable, high-data rate communication in potentially life-threatening situations. This increases their situational awareness, strengthens their decision making and decreases response time by ensuring efficient indoor communication of sensor data, biometric data, pictures or videos. Therefore, a real-life rescue operation was replicated by means of two simultaneously moving firefighters in an office environment. These wideband channel sounder measurements were performed at 3.6 GHz with 80 MHz bandwidth. Four Ultra-Wideband Substrate Integrated Waveguide cavity-backed slot textile antennas were integrated in the front, back, left shoulder and right shoulder sections of the firefighters' jackets, providing up to 4×4 MIMO communication. For this indoor environment, we extract the pertinent OFDM parameters using the RMS delay spread and 50% correlation bandwidth of the sixteen individual SISO channels. Furthermore, we calculate the potential SISO-, 2×2 MIMO- and 4×4 MIMO-OFDM capacities and corresponding data rates. Finally, we show that the 4×4 MIMO setup is more energy efficient and increases both the link reliability and link quality.\",\n \"Title: Vehicle-to-Vehicle Radio Channel Characterization in Crossroad Scenarios.\\nYear: 2016\\n\\nAbstract: Vehicle-to-vehicle (V2V)-communication-based collision avoidance systems detect if two vehicles are on a collision course (e.g., in crossroads, intersections, and highway merging), and they are particularly useful in the absence of line of sight (LOS) owing to buildings, roadside infrastructures, and road bending. Relying on radio measurements using a 4 × 30 multiple-input-multiple-output (MIMO) s...\",\n \"Title: Physical-Statistical Modeling of Dynamic Indoor Power Delay Profiles.\\nYear: 2017\\n\\nAbstract: This paper presents a physical-statistical radio channel power delay profiles model for room-to-room communication systems combining the room electromagnetic theory for modeling deterministic channel components with a geometry-based stochastic channel model with time-variant statistics for modeling stochastic components. The deterministic channel component, i.e., mean power delay spectrum, is comp...\",\n \"Title: Stochastic Geometry Based Coverage Estimation Using Realistic Urban Shadowing Models\\nYear: 2018\\n\\nAbstract: The main contribution of this paper consists in integrating a physically correlated shadowing model of the aggregate interference in a stochastic geometry-based approach. The considered shadowing takes place in a Manhattan urban grid and combines both penetration and corner diffraction when modeling signal transmission from base stations to users. A tractable expression for the network coverage probability is obtained thanks to the framework of stochastic geometry. Our results suggest that the diffracted mechanisms are dominant compared to building penetration. It is also shown that the second order diffracted signal have little impact on the coverage compared to the first order signals.\",\n \"Title: An extension of the RiMAX multipath estimation algorithm for ultra-wideband channel modeling.\\nYear: 2018\\n\\nAbstract: This work presents an extension of the high-resolution RiMAX multipath estimation algorithm, enabling the analysis of frequency-dependent propagation parameters for ultra-wideband (UWB) channel modeling. Since RiMAX is a narrowband algorithm, it does not account for the frequency-dependency of the radio channel or the environment. As such, the impact of certain materials in which these systems operate can no longer be considered constant with respect to frequency, preventing an accurate estimation of multipath parameters for UWB communication. In order to track both the specular and dense multipath components (SMC and DMC) over frequency, an extension to the RiMAX algorithm was developed that can process UWB measurement data. The advantage of our approach is that geometrical propagation parameters do not appear or disappear from one sub-band onto the next. The UWB-RiMAX algorithm makes it possible to re-evaluate common radio channel parameters for DMC in the wideband scenario, and to extend the well-known deterministic propagation model comprising of SMC alone, towards a more hybrid model containing the stochastic contributions from the DMC's distributed diffuse scattering as well. Our algorithm was tested with synthetic radio channel models in an indoor environment, which show that our algorithm can match up to 99% of the SMC parameters according to the multipath component distance (MCD) metric and that the DMC reverberation time known from the theory of room electromagnetics can be estimated on average with an error margin of less than 2 ns throughout the UWB frequency band. We also present some preliminary results in an indoor environment, which indicate a strong presence of DMC and thus diffuse scattering. The DMC power represents up to 50% of the total measured power for the lower UWB frequencies and reduces to around 30% for the higher UWB frequencies.\",\n \"Title: A Novel Target Recognition Based Radio Channel Clustering Algorithm\\nYear: 2018\\n\\nAbstract: In this paper, a novel target recognition based clustering algorithm is proposed for time-varying channels. Power angle spectrum (PAS) is extracted from measurement data by using Bartlett beamformer. Then the clusters in the PAS are separated from the background by using the proposed algorithm, where the amplitude distribution of the elements in the PAS is considered. Moreover, morphology operations are applied to further divide the clusters which are connected to each other. It is found that, the dominating clusters in both line-of-sight (LoS) and non-line-of-sight (NLoS) environments can be well recognized by the proposed algorithm with low computation cost. By using the proposed algorithm, the dynamic changes of the clusters in real-time channel measurement can be clearly observed, without using any high-resolution parameter estimation.\",\n \"Title: A Power-Angle-Spectrum Based Clustering and Tracking Algorithm for Time-Varying Radio Channels.\\nYear: 2019\\n\\nAbstract: Radio channel modeling has been an important research topic, since the performance of any communication system depends on channel characteristics. So far, most existing clustering algorithms are conducted based on the multipath components (MPCs) extracted by using a high-resolution parameter estimation approach, e.g., SAGE or MUSIC, etc. However, most of the estimation approaches require prior inf...\",\n \"Title: Semi-empirical Model of Global Exposure using Stochastic Geometry\\nYear: 2021\\n\\nAbstract: Exposure to electromagnetic fields due to cellular networks in an urban environment is studied using stochastic geometry. We describe a simple but functional and realistic semi-empirical model based on the modeling of base station patterns as Poisson Point Processes and applied to two Brussels municipalities. Using this model, a study of the impact of base station densification is performed accord...\",\n \"Title: Cluster-Based Characterization and Modeling for UAV Air-to-Ground Time-Varying Channels\\nYear: 2022\\n\\nAbstract: With the deep integration between the unmanned aerial vehicle (UAV) and wireless communication, UAV-based air-to-ground (AG) propagation channels need more detailed descriptions and accurate models. In this paper, we aim to conduct cluster-based characterization and modeling for AG channels. To our best knowledge, this is the first study that concentrates on the clustering and tracking of multipath components (MPCs) for time-varying AG channels. Based on measurement data at 6.5 GHz with a bandwidth of 500 MHz, we first estimate potential MPCs utilizing the space-alternating generalized expectation-maximization (SAGE) algorithm. Then, we cluster the extracted MPCs by employing K-Power-Means (KPM) algorithm under multipath component distance (MCD) measure. For characterizing time-variant clusters, we exploit a clustering-based tracking (CBT) method, which efficiently quantifies the survival lengths of clusters. Ultimately, we establish a cluster-based channel model, and validations illustrate the accuracy of the proposed model. This work not only promotes a better understanding of AG propagation channels but also provides a general cluster-based AG channel model with certain extensibility.\",\n \"Title: Spatial Loss Field for Outdoor Micro-Cells\\nYear: 2022\\n\\nAbstract: In propagation analysis it is assumed that existing shadowing losses are due to obstacles through the propagation path between two transceivers. Although classically modelled as a log-normal random variable, special attention is being recently put into models where shadowing is considered as a consequence of an Underlying Spatial Loss Field (USLF) accounting for attenuation, under Radio Channel Tomography (RCT) framework. In this paper we address the task of making shadowing predictions for transceiver locations, without the need of measurements for those locations. A spatial loss field estimate is produced from measurements for a given set of transceiver locations, and used as an input to predict the shadowing at another set of transceiver locations. Moreover, new weighting functions are proposed and developed from channel parameter estimates of the propagation paths.\",\n \"Title: Mm-Wave Massive MIMO Channel Sounding in Industrial IoT Scenarios\\nYear: 2022\\n\\nAbstract: This paper presents results of massive multi-input multi-output (mMIMO) channel characteristics based on measurements carried out in an industrial environment at frequency ranges from 26 GHz to 30 GHz. Three different propagation conditions were considered, i.e. line-of-sight (LOS), obstructed LOS (OLOS) and non-LOS (NLOS), and two types of virtual antenna arrays were measured using monopole antennas, i.e. the planar and cubic arrays composed of 21x21 and 5x5x5 elements, respectively. The main results on large-scale parameters as well as an analysis on specular and dense multi-path components are then presented. Finally, the spatial correlation properties over a large antenna arrays were investigated in LOS and OLOS scenarios.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":62,"string":"62"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":289,"string":"289"}}},{"rowIdx":290,"cells":{"question_id":{"kind":"string","value":"Zheng Chu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Robust transceiver designs in multiuser MISO broadcasting with simultaneous wireless information and power transmission.\" using the following items: 1. Robust optimization problem\n2. Multiuser broadcasting system\n3. Wireless information and power transmission\n4. Semidefinite program\n5. Interior point algorithm"},"answer":{"kind":"string","value":"In this paper, we address a new robust optimization problem in a multiuser multiple-input single-output broadcasting system with simultaneous wireless information and power transmission, where a multi-antenna base station (BS) sends energy and information simultaneously to multiple users equipped with a single antenna. Assuming that perfect channel-state information (CSI) for all channels is not available at the BS, the uncertainty of the CSI is modeled by an Euclidean ball-shaped uncertainty set. To optimally design transmit beamforming weights and receive power splitting, an average total transmit power minimization problem is investigated subject to the individual harvested power constraint and the received signal-to-interference-plus-noise ratio constraint at each user. Due to the channel uncertainty, the original problem becomes a homogeneous quadratically constrained quadratic problem, which is NP-hard. The original design problem is reformulated to a relaxed semidefinite program, and then two different approaches based on convex programming are proposed, which can be solved efficiently by the interior point algorithm. Numerical results are provided to validate the robustness of the proposed algorithms."},"correct_answer":{"kind":"string","value":"In this paper, we address a new robust optimization problem in a multiuser multiple-input single-output broadcasting system with simultaneous wireless information and power transmission, where a multi-antenna base station (BS) sends energy and information simultaneously to multiple users equipped with a single antenna. Assuming that perfect channel-state information (CSI) for all channels is not available at the BS, the uncertainty of the CSI is modeled by an Euclidean ball-shaped uncertainty set. To optimally design transmit beamforming weights and receive power splitting, an average total transmit power minimization problem is investigated subject to the individual harvested power constraint and the received signal-to-interference-plus-noise ratio constraint at each user. Due to the channel uncertainty, the original problem becomes a homogeneous quadratically constrained quadratic problem, which is NP-hard. The original design problem is reformulated to a relaxed semidefinite program, and then two different approaches based on convex programming are proposed, which can be solved efficiently by the interior point algorithm. Numerical results are provided to validate the robustness of the proposed algorithms."},"documents":{"kind":"list like","value":["Title: Cooperative multi-object tracking method for Wireless Video Sensor Networks\nYear: 2011\n\nAbstract: For the enormous number and the limited energy of network nodes in the wireless video sensor networks (WVSN) environment, to fulfil the complicated tasks, multiple sensor nodes should collaborate with each other. A cooperative multi-object tracking method for Wireless Video Sensor Networks is proposed in this paper. The proposed method is focused on the solution of cooperative multi-object tracking among multiple sensor nodes when an object leaves the view field of the tracking node. The main contributions of our proposed method are that: (1) the sensing model of a video sensor and Kalman filter is utilized to achieve optimal sensor selection. (2) Projective Invariants are employed to integrate information from the related nodes. The experimental results show that the proposed method is effective for resolving the problem of tracking relay.","Title: A multi-object detection and tracking method in wireless video sensor networks\nYear: 2012\n\nAbstract: Most multi-object detection and tracking techniques suffer from the well-known \"multi-object occlusion\" problem. The abundant nodes of wireless video sensor networks (WVSNs) can be utilized to solve the problem, and the video nodes in WVSN have limited calculation capability and energy. In order to achieve effective multi-object tracking using WVSN, the main contributions of our proposed method are that: (1) the limits of field of view (FOV) of every video nodes are utilized to establish the consistent labeling of the objects in different views. (2) Mobile Agent is employed to communicate among network nodes, so the objects are assigned correct labels after multi-object occlusion. The performance of the approach has been demonstrated on real-world and the experimental results show that the proposed method is effective for resolving multi-object occlusions and meets the requirement of WVSN.","Title: Robust Outage Secrecy Rate Optimizations for a MIMO Secrecy Channel\nYear: 2015\n\nAbstract: This letter investigates robust secrecy rate optimization techniques for a multiple-input-multiple-output (MIMO) wiretap channel in the presence of a multiantenna eavesdropper. In particular, two robust secrecy rate optimization problems are studied: robust power minimization with an outage secrecy rate constraint and robust secrecy rate maximization subject to the outage secrecy rate and transmit power constraints. Here, it is assumed that the legitimate transmitter has perfect channel state information (CSI) of the legitimate receiver and imperfect CSI of the eavesdropper. Both robust problems are not convex in terms of transmit covariance matrix and the outage secrecy rate constraint. Hence, we propose a conservative approximation approach to reformulate this outage secrecy rate constraint by exploiting the Bernstein-type inequality to obtain a tractable solution for these two robust problems. Numerical results have been provided to validate the convergence and the performance of the proposed robust algorithms.","Title: Robust secrecy rate optimisations for multiuser multiple-input-single-output channel with device-to-device communications\nYear: 2015\n\nAbstract: In the present study, the authors investigate robust secrecy rate optimisation problems for a multiple-input-single-output secrecy channel with multiple device-to-device (D2D) communications. The D2D communication nodes access this secrecy channel by sharing the same spectrum, and help to improve the secrecy communications by confusing the eavesdroppers. In return, the legitimate transmitter ensures that the D2D communication nodes achieve their required rates. In addition, it is assumed that the legitimate transmitter has imperfect channel state information of different nodes. For this secrecy network, the authors solve two robust secrecy rate optimisation problems: (a) robust power minimisation problem, subject to the probability based secrecy rate and the D2D transmission rate constraints; (b) robust secrecy rate maximisation problem with the transmit power, the probabilistic based secrecy rate and the D2D transmission rate constraints. Owing to the non-convexity of robust beamforming design based on two statistical channel uncertainty models, the authors present two conservative approximation approaches based on `Bernstein-type' inequality and `S-Procedure' to solve these robust optimisation problems. Simulation results are provided to validate the performance of these two conservative approximation methods, where it is shown that `Bernstein-type' inequality based approach outperforms the `S-Procedure' approach in terms of achievable secrecy rates.","Title: Simultaneous Wireless Information Power Transfer for MISO Secrecy Channel.\nYear: 2016\n\nAbstract: This paper investigates simultaneous wireless information and power transfer (SWIPT) for a multiple-input–single-output (MISO) secrecy channel. First, transmit beamforming without artificial noise (AN) is designed to achieve the secrecy rate maximization problem subject to the transmit power and the energy harvesting (EH) constraints. This problem is not convex, but this can be solved by applying a bisection search to a sequence of the associated power minimization problems, each of which can be solved by using a novel relaxation approach. Moreover, we extend our proposed algorithms to the robust case by incorporating channel uncertainties. Then, transmit beamforming with AN is investigated for the secrecy rate maximization problem, where two relaxation approaches are presented, i.e., a two-level optimization algorithm and a successive convex approximation (SCA), to solve the secrecy rate maximization problem. In addition, tightness analyses of rank relaxation are provided to show that the optimal transmit covariance matrix exactly returns rank one. Simulation results are provided to validate the performance of the proposed algorithms.","Title: Joint relay beamforming and power splitting ratio optimization in a multi-antenna relay network\nYear: 2014\n\nAbstract: This paper investigates simultaneous wireless information and power transfer (SWIPT) in a multi-antenna relay network. We consider robust transmit power minimization problem at the relay by jointly optimizing beamforming and adaptive power splitting subject to the signal-to-inference-plus-noise (SINR) and energy harvesting constraints by incorporating channel uncertainty model. We formulate the original non-convex problem into semidefinite programming problem (SDP) by relaxing rank-one constraint and we show the optimal solution of SDP is always rank-one. Simulation results are provided to validate the performance of the proposed robust algorithms.","Title: Secrecy rate optimization for a MIMO secrecy channel based on Stackelberg game\nYear: 2014\n\nAbstract: In this paper, we consider a multi-input-multi-output (MIMO) wiretap channel with a multi-antenna eavesdropper, where a private cooperative jammer is employed to improve the achievable secrecy rate. The legitimate user pays the legitimate transmitter for its secured communication based on the achieved secrecy rate. We first approximate the legitimate transmitter covariance matrix by employing Taylor series expansion, then this secrecy rate problem can be formulated into a Stackelberg game based on a fixed covariance matrix of the transmitter, where the transmitter and the jammer try to maximize their revenues. This secrecy rate maximization problem is formulated into a Stackelberg game where the jammer and the transmitter are the leader and follower of the game, respectively. For the proposed game, Stackelberg equilibrium is analytically derived. Simulation results are provided to show that the revenue functions of the legitimate user and the jammer are concave functions and the Stackelberg equilibrium solution has been validated.","Title: Harvest-and-jam: Improving security for wireless energy harvesting cooperative networks\nYear: 2014\n\nAbstract: The emerging radio signal enabled simultaneous wireless information and power transfer (SWIPT), has drawn significant attention. To achieve secrecy transmission by cooperative jamming, especially in the upcoming 5G networks with self-sustainable mobile base stations (BSs) and yet not to add extra power consumption, we propose in this paper a new relay protocol, i.e., harvest-and-jam (HJ), in a relay wiretap channel with an additional set of spare helpers. Specifically, in the first transmission phase, a single-antenna transmitter (Tx) transfers signals carrying both information and energy to a multi-antenna amplify-and-forward (AF) relay and a group of multi-antenna helpers; in the second transmission phase, the AF relay processes the information and forwards it to the receiver while each of the helpers generates an artificial noise (AN), the power of which is constrained by its previously harvested energy, to interfere with the eavesdropper. By optimizing the transmit beamforming matrix for the AF relay and the covariance matrix for the AN, we maximize the secrecy rate for the receiver subject to transmit power constraints for the AF relay and all helpers. The formulated problem is shown to be non-convex, for which we propose an iterative algorithm based on alternating optimization. Finally, the performance of the proposed scheme is evaluated by simulations as compared to other heuristic schemes.","Title: Secrecy Rate Optimizations for a MISO Secrecy Channel with Multiple Multiantenna Eavesdroppers.\nYear: 2016\n\nAbstract: This paper investigates secrecy rate optimization problems for a multiple-input-single-output (MISO) secrecy channel in the presence of multiple multiantenna eavesdroppers. Specifically, we consider power minimization and secrecy rate maximization problems for this secrecy network. First, we formulate the power minimization problem based on the assumption that the legitimate transmitter has perfec...","Title: To Harvest and Jam: A Paradigm of Self-Sustaining Friendly Jammers for Secure AF Relaying\nYear: 2015\n\nAbstract: This paper studies the use of multi-antenna harvest-and-jam (HJ) helpers in a multi-antenna amplify-and-forward (AF) relay wiretap channel assuming that the direct link between the source and destination is broken. Our objective is to maximize the secrecy rate at the destination subject to the transmit power constraints of the AF relay and the HJ helpers. In the case of perfect channel state infor...","